Apparatus for estimating a magnitude of leakage from a surgical tourniquet system while pressure in a cuff of the system is regulated near a reference pressure.

Surgical tourniquet systems are commonly used to stop the flow of arterial blood into a portion of a patient's limb, thus creating a clear, dry surgical field that facilitates the performance of a surgical procedure and improves outcomes. A typical surgical tourniquet system of the prior art includes a tourniquet cuff for encircling a patient's limb at a desired location, a tourniquet instrument, and flexible pneumatic tubing connecting the cuff to the instrument. In some surgical tourniquet systems of the prior art, the tourniquet cuff includes an inflatable portion, and the inflatable portion of the cuff is connected pneumatically through flexible plastic tubing and one or more connectors to a tourniquet instrument. A typical tourniquet instrument of the prior art includes a pressure regulator to maintain the pressure in the inflatable portion of the cuff, when applied to a patient's limb at a desired location, near a reference pressure that is above a minimum pressure required to stop arterial blood flow past the cuff during a time period suitably long for the performance of a surgical procedure. Many types of such pneumatic surgical tourniquet systems have been described in the prior art, such as those described by McEwen in U.S. Pat. No. 4,469,099, No. 4,479,494, No. 5,439,477 and by McEwen and Jameson in U.S. Pat. No. 5,556,415 and No. 5,855,589.
In surgical tourniquet systems of the prior art, leakage of pressurized gas from the tourniquet cuff, or from pneumatic tubing between the instrument and cuff, or from connectors attaching the tubing to the cuff and instrument may affect safety, performance, and reliability. The 2007 Recommended Practices for the Use of the Pneumatic Tourniquet in the Perioperative Practice Setting (RPs) of the US Association of periOperative Nurses (AORN) recommend that the tourniquet cuff, tubing, and connectors should be kept clean and in good working order. The AORN RPs further recommend, based on published literature, that the tourniquet cuff, tubing, and connectors should be inspected for cracks and leaks because unintentional pressure loss can result from loose tubing connectors, deteriorated tubing, or cuff bladder leaks, and may result in patient injury. At present, such inspections and checking are performed manually and often inconsistently by users, or only after a hazardous incident or patient injury has occurred. As a result, defective and leaking tourniquet cuffs, connectors and tubing may remain in use for long periods of time. Also, users may not be alerted to defects which may be small initially but which may increase to become significant hazards, either slowly or very rapidly, if remedial action is not taken. Unauthorized reprocessing and reuse of cuffs manufactured to be single-use disposable cuffs may introduce leakage hazards if such cuffs are not carefully inspected and checked before each reuse because improper, uncontrolled and unlimited reprocessing may impair the shape and integrity of the pneumatic seals of cuff connectors. Even if disposable tourniquet cuffs are used as single-use products, and if it is assumed that such cuffs are not leaking at time of first use, the tubing and connectors that connect the disposable cuffs to the tourniquet instrument may leak and such leakage may go undetected, allowing the leaking tubing or connectors to remain in use until an obvious patient hazard or injury occurs, and during which time other limitations in tourniquet safety, performance and reliability are produced, as described below.
To alert a user to an extreme loss of tourniquet cuff pressure from leakage, for example as may be caused by a pneumatic disconnection between the cuff and the instrument, some surgical tourniquet systems of the prior art include audio-visual leakage alarms. Unfortunately, such alarms in prior-art systems are typically produced only after there has been a decrease in actual cuff pressure to a level that is well below the reference pressure for a sustained period of time, and thus only after substantial blood flow past the cuff may have occurred. This adversely affects the safety and quality of surgery before the user is alerted to the need for remedial action.
Sustained pneumatic leakage that is not detected by prior-art tourniquet systems is undesirable in surgery and may be hazardous. In the past, undetected pneumatic leakage led users of prior-art systems to set tourniquet pressures at reference levels that were substantially higher than required physiologically to compensate for intra-operative reductions in cuff pressure that users had observed but had not been able to attribute to obvious leakage. However, setting unnecessarily high pressures is hazardous because in the medical literature higher tourniquet pressure levels have been associated with higher probabilities of patient injuries to nerves and soft tissues. More recently, some surgical tourniquet systems of the prior art have attempted to compensate for undetected levels of pneumatic leakage in the design of their pressure regulators. In typical systems, the pressure regulator is designed to maintain cuff pressure within a predetermined pressure range from a reference pressure, and any fluctuations beyond that range are offset by actuation of a pump, reservoir, or valve in an effort to bring the cuff pressure back within the range. If there is pneumatic leakage sufficient to cause the cuff pressure to decrease beyond the predetermined pressure range, actuation of the pressure regulator may bring it back within range, and if not a pressure-regulation alarm is produced. Such systems of the prior art may compensate for significant levels of sustained, undetected leakage without producing any indication of leakage or alarm for the user. As a result of this limitation, defective and leaking tourniquet cuffs, connectors, and tubing may remain in use for long periods of time. Further, sustained leakage may produce an error in the indicated tourniquet cuff pressure in single-port tourniquet systems of the prior-art which estimate cuff pressure by measuring pneumatic pressure within the tourniquet instrument. Also, users are not alerted to defects which may be small initially but which may increase to become significant hazards, either slowly or very rapidly, if remedial action is not taken. For typical surgical tourniquet systems of the prior art three limitations in the performance and reliability of their pressure regulators exist in the presence of undetected pneumatic leakage. First, tourniquet cuff pressure fluctuates unnecessarily as decreases in cuff pressure are offset by the actuations of the pressure regulator. Second, unnecessarily frequent actuation of the pressure regulator reduces the operational life and reliability of its mechanical components, increases the cost of maintaining and replacing those components, and may increase capital costs by necessitating early replacement of the entire tourniquet instrument. Third, operation of prior-art tourniquet systems on battery power is impaired. Typical tourniquet systems of the prior art may be powered either by external AC power or by an internal battery, so that they can continue to operate safely in the event of a sudden interruption of external power, and so that they can operate independently of external AC power for a prolonged period of time, for example during transportation of a patient from a pre-operative room to the operating room, or to facilitate surgery under emergency or battlefield conditions. However, in the presence of sustained leakage pneumatic leakage, the operational time of a tourniquet system when powered by an internal battery for surgery may be substantially reduced due to unnecessary actuations of the pressure regulator. Additionally, the overall life of the internal battery may be significantly reduced, reducing the performance and reliability of the tourniquet system and thereby increasing costs and hazards.
There is a need for a leak detector for surgical tourniquet systems that overcomes the above-described limitations of the prior art. No surgical tourniquet system known in the prior art rapidly detects leakage in the tourniquet cuff, pneumatic tubing, or pneumatic connectors between the cuff and pressure regulator of the tourniquet instrument while cuff pressure is maintained near a reference pressure by the pressure regulator. Further, no system known in the prior art estimates the magnitude of pneumatic leakage while cuff pressure is regulated near the reference pressure. No prior-art system determines the level of hazard to a patient associated with the magnitude of any pneumatic leakage estimated during cuff pressure regulation. Also, no prior-art tourniquet system includes means for communicating with a remote display, printer, alarm or similar apparatus to produce an indication perceptible by a user of the level of hazard associated with any pneumatic leakage detected during cuff pressure regulation.

Apparatus and method for estimating leakage in a surgical tourniquet system


A power on/off circuit with a lock function includes a momentary type main switch connected to ground, a two-circuit two-contact lock switch coupled to, a switching state holding circuit, a load and a power supply. One of the switching circuits in the lock switch is connected between the main switch and the input terminal (CK) of the switching state holding circuit. The other switching circuit in the lock switch is connected between the main switch and the reset terminal (CLR) of the switching state holding circuit. The switching state of the main switch is held by the switching state holding circuit, and the state is maintained unless a reset signal is applied to the switching state holding circuit. The lock switch only functions to generate the reset signal so that the lock switch does not cut off the supply of current to the load as in a conventional shaver.

Portable shavers are equipped with a main switch which turns a motor on/off, and a locking system which stops this function. The locking system is provided to prevent the main switch from being accidentally turned on due to an external shock and the like. As a result, the motor will not rotate and consume battery energy, when the portable shaver is contained and carried in a suitcase or the like.
As a practical means for realizing this locking system, there are known mechanical locking means and electrical means utilizing a slide switch. Mechanical locking means are arranged so that the switch bar of the main switch is mechanically locked to prevent it from moving to the on-position when the main switch is in the off-position, and the main switch is not mechanically locked when the main switch is in the on-position. On the other hand, as shown in FIG. 1, with the locking system using electrical means, a locked state is realized by turning a lock slide switch 28, which is connected in series with a main switch 27, to the off-position, so that the power to the load will be cut off.
In recent years, push type switches have come into use widely as the main switch. The push type switches are a type of switch turned on/off by depressing a switch button, and there are types in which the depressed state is held (alternate type) and types in which the depressed state returns to the previous state as soon as the finger is removed (momentary type). Especially, soft touch momentary type switches are used frequently nowadays.
In battery operated portable shavers utilizing a momentary type switch as the main switch (hereinafter referred to as momentary switch type shavers), a pulse is generated each time the main switch is depressed, and the switched state is held by means of a state holding circuit until the next pulse is sent.
As shown in FIG. 1, in conventional shavers in which an alternate type main switch 27 and a lock switch 28 are connected in series, the rotation of a motor 23 is stopped when the lock switch 28 is turned on with the main switch 27 in the on state. Thus, the motor can be stopped not only by the main switch but also by the lock switch. This results in a problem in that it is difficult to determine which switch is the main switch.
Such a problem does not exist when a mechanical locking system is used. However, locking means utilizing a mechanical means cannot be used in momentary switch type shavers. This is because a switch on/off signal cannot be sent to the state holding circuit when the main switch operation is disabled by the mechanical means. On the other hand, if a microprocessor is used, it is possible to realize a momentary switch type shaver in which the function of the main switch and lock switch are clearly separated. However, microprocessors are rather expensive and require expensive development costs for deriving its software.
Momentary type switches have recently come into use not only in shavers as mentioned above, but as the main switch of headphone stereo sets. However, headphone stereo sets are conventionally not equipped with a lock switch. Therefore, when a headphone stereo set having this type of main switch is carried in a pocket and the like, there is a problem that the main switch can be depressed, and the headphone stereo set operates, and consequently the battery energy is consumed completely.


The present invention provides a method for producing cloned cows by employing in vitro maturation of oocytes and nuclear transfer techniques. The method comprises collecting donor somatic cell lines from cows; maturing oocytes extracted from an ovary in vitro; enucleating the oocyte by cutting a portion of the zona pellucida and squeezing out a portion of the cytoplasm, including the first polar body; inserting the donor somatic cell into the oocyte; electrofusing the cells to produce embryos; post-activating the embryos; transferring them into surrogate cows to produce cloned calves.

The present invention relates to a method for producing cloned cows, more specifically, a method for producing somatic cell-derived cloned cows by employing in vitro maturation and subsequent enucleation of oocytes, nuclear transfer, electrofusion and activation of embryos, postactivation and in vitro culture of the embryos and transfer of the embryos into surrogate cows. It also relates to the embryos and cloned cows produced by the method described above.
Animals have long been considered to be produced by fertilization involving male and female gametes. However, tremendous efforts have been made on generating cloned animals with the identical appearance and genetic characteristics.
Cloning of zygotes has been known to be possible only in amphibians for 30 years until the success in producing a cloned offspring by substituting a pronucleus of one-cell zygote in mice(see: McGrath and Solter, Science, 220:1300-1302, 1983). Despite this first success in cloning animals, the same success in industrial animals(see: Wakayama et al., Nature, 394:369-374, 1998) has been reported much later since production of cloned mice employing mature oocytes and zygote blastomeres after 2-cell stage have several problems such as decrease in reprogramming.
With regard to the production of cloned industrial animals by nuclear transfer, it was the first report that an offspring was produced in sheep by employing blastomeres of 8- to 16-cell zygote as donor cells(see: Wiladsen, Nature, 320:63-65, 1986). Since then, only the blastomeres of zygote with totipotency by which a cell can be differentiated into every single cell have been considered to be cloned by nuclear transfer. However, through the continuous research effort, the first cloned sheep was produced by introducing nuclei from somatic cells(see: Wilmut et al., Nature, 385:810-813, 1997), thus making correction in the prior developmental theory and enabling many successful examples to be reported in production of cloned cows(see: Wells et al, Reprod. Fertil. and Develop., 10:369-378, 1998) and pigs.
The prior art methods are, however, proven to be less satisfactory in the sense that the yield of embryos produced by nuclear transfer is relatively low, which resulted in the low production rate of cloned animals.
Under the circumstances, there are strong reasons for exploring and developing an improved method for producing the somatic cell-derived embryos in terms of the yield of embryos produced by nuclear transfer.
In accordance with the present invention, it has been discovered that: the yield of embryos produced by nuclear transfer can be dramatically increased by shortening time of oocyte manipulation and improving the nuclear transfer and activation rate when donor cells are transferred into enucleated oocytes, by which somatic cell-derived cloned cows can be produced in an efficient manner.
A primary object of the present invention is, therefore, to provide a method for producing cloned cows by nuclear transfer of somatic cells.
The other object of the invention is to provide cloned cow embryos produced by the said method.
Another object is to provide somatic cell-derived cloned cows produced by the said method.


A flexible cable guide member and assembly, the assembly including first and second cable guide members each having a curved wall with open ends. The curved walls define first and second cable pathways respectively for receiving a telecommunications cable. A first end of the first guide member defines a socket. A second end of the second guide member is rounded to be received by the socket of the first guide member to produce a ball-and-socket joint between the first and second guide members. The second guide member is snap-fit into the socket of the first cable guide member. The guide members define longitudinal slots to allow cables to be added or removed from the assembly. The first and second guide members are preferably identical.

This invention pertains to a system for the management and routing of cables, such as telecommunications cables. More particularly, this invention pertains to flexible enclosure assemblies for cable management systems.
In the telecommunications industry, the use of optical fibers for signal transmission is accelerating. With the increased utilization of optical fiber systems, optical fiber cable management requires industry attention. Similar issues exist with other telecommunications cables such as copper-based cables.
One area of telecommunications cable management that is necessary is the routing of cables from one piece of equipment to another. For example, in a telecommunications facility, optical fiber cables may be routed between fiber distribution equipment and optical line terminating equipment. In buildings and other structures which carry such equipment, the cable routing can take place in concealed ceiling areas or in any other manner to route cables from one location to another. Accordingly, such routing systems often include a plurality of trough or enclosure members, fittings and couplings for routing the cables. U.S. Pat. Nos. 5,067,678; 5,316,243; and 5,752,781 show various cable routing systems.
When routing cables, it is desirable that the routing system will be easy to install. For example, providing a continuous cable path throughout the system can be a challenge, such as when obstacles or misalignments arise during installation of the system. There is a need for devices which make system installation easier and less reliant on precisely aligned components. There is a need for an improved, simplified, cost effective system for making adjustments in the alignment of a cable management system.
The present invention relates to a flexible cable guide member and assembly. The assembly includes first and second cable guide members having a curved wall with open ends. The curved walls define first and second cable pathways respectively for receiving a telecommunications cable. A first end of the first guide member defines a socket. A second end of the second guide member is rounded to be received by the socket of the first guide member to produce a ball-and-socket joint between the first and second guide members. The second guide member is snap-fit into the socket of the first cable guide member. The guide members define longitudinal slots to allow cables to be added or removed from the assembly. The first and second guide members are preferably identical.
Another aspect of the present invention relates to the method of retaining cables inside a cable guide assembly. The method includes the step of twisting or rotating one cable guide member relative to another so that longitudinal slots through each guide member no longer overlap, thereby enclosing the cables.
A variety of advantages of the invention will be set forth in part in the description that follows, and in part will be apparent from the description, or may be learned by practicing the invention. It is to be understood that both the foregoing general description and the following detailed description are explanatory only and are not restrictive of the invention as claimed.


A refiner plate assembly and method includes an annular arrangement of adapter subplates that mount to a refiner disk of a disk refiner using a conventional mounting technique, such as bolted in a standard pattern associated with the particular disk refiner. The adapter subplate arrangement remains mounted to the disk and provides a universal mounting surface for an annular arrangement of individual removable refiner segments. A steam and/or accept evacuation channel is provided in this assembly via filter passages at a radially intermediate location in one or more refiner segments which communicate with a recess or channel in one or more associated adapter subplates that direct the steam and/or accepts through outlet ports in the outer rim of the adapter subplate(s). Refining efficiency is provided in a universal refiner plate assembly by eliminating steam volume and already refined pulp from outer portions of the refining zone. The filter section(s) can be placed at an optimal location of high volume fraction of pulp fibers where mounting hardware is typically located in conventional refiner segments.

1. Technical Field
The present invention relates to disk refiners and more particularly to improvements in refiner plates and mounting assemblies therefore.
2. Description of the Related Art
Disk refiners are used in the paper manufacturing industry to prepare the cellulose fibers of a paper pulp into a desired condition prior to delivering the pulp to the papermaking machine. Double disk refiners, such as described in U.S. Pat. No. 4,083,503, have refiner plates attached to a rotating disk, or rotor, and complementary refiner plates attached to an opposing, non-rotating disk, or stator. Multiple disk refiners, such as described in U.S. Pat. No. 4,783,014, have a plurality of rotatable and non-rotatable refiner plates interleaved within a refining chamber of the refiner. Counter-rotating disk refiners, such as described in U.S. Pat. No. 4,129,263, have two counter-rotating refining disks each mounted to its own motor-driven shaft.
There are many different disk refiners of differing configurations and diameters. There are also many different types of refiner plates. One type of a refiner plate is a complete annular plate which is cast or otherwise manufactured as  a one-piece member. A major disadvantage of complete annular refining plates is the high cost of fabrication, and difficulties associated with the transport and installation of such a large, heavy component. These issues are avoided by a refiner plate which comprises a plurality of individual segments which cooperatively form an annular plate when fitted together. U.S. Pat. Nos. 4,039,154 and 5,425,508 provide examples refiner plates having a plurality of individual segments, which are assembled to form a complete annular plate.
Moreover, refiner plates have a working refining surface that is typically formed by a plurality of spaced apart, raised, rib-like projections, generally called "bars". There are many refiner plate patterns which are well-known within the paper industry. The bars and other portions of the working surface are gradually abraded or worn away from use, and are subject to damage from excessive loading, such that they require replacement periodically. Thus, another advantage in using segmented refiner plates pertains to replacement of worn or damaged bars. Replacing an entire annular refiner plate due to wear or damage in a discrete part of the refiner plate is inefficient and costly compared to replacing only the segment or segments that are worn or damaged.
Furthermore, regardless of the refiner plate type or bar pattern, the mounting arrangement can vary by refiner manufacturer, and even a single refiner manufacturer may utilize different plate mounting arrangements in terms of the number, size and spacing of the mounting bolts, especially when the overall size of the plates vary considerably. Consequently, a refiner plate manufacturer supplying refiner plates for several manufacturer's refiners have been required to manufacture numerous different refiner plates of the same diameter to be used in the many different disk refiners, even if the same bar configuration is used.
This latter situation can be improved by using an adapter to mount the refiner segments. U.S. Pat. No. 5,934,585, assigned to the assignee of the present invention, and hereby incorporated be reference herein, provides an example of mounting assembly in which an adapter has holes that match the standard bolt pattern of the refiner disk. Refiner segments then mount to the adapter using a  clamping ring. Since only the adapter bolts to the refiner disk, and since the adapters are not wear parts, for any given bar pattern refiner manufacturers can supply a single replacement refiner segment type for different disk refiners.
Additionally, while the refiner plate bars can be sized and aligned in many different ways, they generally narrow in the radial outward direction to facilitate courser to finer refining of the pulp and are also aligned in some way that facilitates flow of the pulp between the bars toward the outer periphery of the refiner plate. One additional issue with existing refiner plates, is that it is inefficient to refine pulp, for example at finer bars located in a radially outer region of the refiner segment, that has already been sufficiently refined to an acceptable size. U.S. Pat. No. 7,347,392, which is also assigned to the assignee of the present invention, and hereby incorporated as though fully set forth herein, provides an example of refiner plates that have internal flow channels through which steam and "accepts" can be carried away from the refining surface between the refiner plates so that they are not refined further. While this provides a significant improvement in efficiency when compared to conventional large refiner segments, it complicates the manufacturing process. Sand casting, a less accurate and more costly technique, is used to create sand core in the casting mold that forms the internal flow channels in the segment. This can lead to imperfections or defects in the cast refiner segment as a result of the release gas into the molten steel as the sand is burned off during the casting process.

Refiner plate assembly and method with evacuation of refining zone


A process for the simultaneous manufacture of pure methyl tertiary butyl ether (MTBE) and a substantially isotubene-free mixture of C.sub.4 -hydrocarbons, by reacting the isobutene contained in the mixture of C.sub.4 -hydrocarbons with excess methanol in the liquid phase at elevated temperatures on strongly acid, macroporous, organic ion exchange resins.. The process has the following steps:. (a) methanol and isobutene are reacted in a molar ratio of 2:1 to 5:1 at temperatures between 30.degree. and 100.degree. C.; PA0 (b) the unconverted hydrocarbons are then removed as the top product under a pressure of 2 to 10 bars from a first rectification column; PA0 (c) the bottom product from this first column is rectified in a second column under normal pressure or under a slight excess pressure of up to 2 bars at the top of the column, the bottom product of this rectification is recycled to reaction zone (a), if necessary, after separating off a portion of the tertiary butanol formed and the C.sub.8 -olefins; and PA0 (d) the distillate from this second column is rectified in a third rectification column under a pressure of 5 to 30 bars, the distillate thus obtained is recycled into the feed to the second column and pure methyl tertiary butyl ether is withdrawn from the bottom of the third column.

The field of the invention is the preparation of methyl tertiary butyl ether (MTBE) by the catalytic addition of methanol to isobutene. The state of the art of this preparation may be ascertained by reference to U.S. Pat. Nos. 2,480,940; 2,922,822; 3,121,124; 3,482,952; 3,726,942; 3,940,450 and 4,039,590, the disclosures of which are incorporated herein.
It is known that methyl tertiary butyl ether (MTBE) can be manufactured by an acid catalyzed addition reaction of methanol with isobutene. Catalysts which have become widely used for the acid catalyzed addition reaction are sulphonated organic resins, such as disclosed in U.S. Pat. No. 2,480,940, and especially the sulphonated polystyrene resins crosslinked with divinylbenzene, as disclosed in U.S. Pat. No. 3,922,822, which can be of a gelatinous nature or can possess a sponge structure with macropores, in order to increase the surface area and thus to increase the rate of reaction. British Pat. No. 957,000, Example 8, and U.S. Pat. No. 3,482,952 disclose the method of increasing the surface area.
Since the reaction between methanol and isobutene proceeds very selectively, it is in general not pure isobutene, but an isobutene-containing mixture of hydrocarbons which is employed. In particular, the crack C.sub.4 hydrocarbon cut freed from butadiene--that is to say the so-called raffinate I--is employed for the reaction. However, other isobutene-containing mixtures of C.sub.4 -hydrocarbons can also be used such as disclosed in U.S. Pat. Nos. 3,121,124 and 4,039,590.
When raffinate I is employed for the manufacture of MTBE, the unconverted residue of the hydrocarbon mixture is termed raffinate II. When raffinate II is employed as the starting material for the manufacture of further products, such as, for example, maleic anhydride or methyl ethyl ketone, or for obtaining 1-butene or in polymerization reactions, the standards of quality demanded of raffinate II are high. In particular in the case of its use for obtaining 1-butene from raffinate II by distillation, the isobutene content of raffinate II must be substantially less than 1% and preferably even less than 0.25 percent by weight, since the isobutene cannot be separated off from 1-butene by distillation and therefore remains in its entirety in the 1-butene. However, a maximum content of isobutene of less than 0.25 percent by weight in raffinate II means that when the isobutene is removed by reaction an isobutene conversion of at least 99.75% must be achieved.
When isobutene is reacted with methanol to give MTBE, the product is not pure MTBE, but only MTBE/methanol azeotrope and methanol. Solutions to the problems of separating the methanol from the MTBE have already been proposed, for example by an extractive distillation with dimethylsulphoxide, as disclosed in Japanese published application No. 73-00509, now Japanese Pat. Sho No. 48-509 or by a water wash, as disclosed in British Pat. No. 1,369,889, and U.S. Pat. No. 3,726,942. In U.S. Pat. No. 3,940,450, the separation of methanol and MTBE is carried out in two stages using pentane as an auxiliary material. All of these processes are relatively involved, since the auxiliary materials employed have to be removed again virtually completely from the MTBE and the methanol. The isobutene conversions achievable are unsatisfactory. In the process according to U.S. Pat. No. 3,726,942, only 70% of the isobutene is converted to MTBE, while according to U.S. Pat. Nos. 3,940,450, a MTBE yield of 80% is achieved.
U.S. Pat. No. 3,979,461 and 4,071,567 describe processes for the manufacture of MTBE by reacting isobutene containing mixtures of C.sub.4 -hydrocarbons with methanol in two reaction zones. However, even with these two processes, adequately high isobutene conversions are not achievable in a conrolled manner, where the lowest isobutene content is given as 0.27% in Example 6 of U.S. Pat. No. 3,979,461. In order to achieve high isobutene conversions in the manufacture of methanol-free MTBE it is necessary to carry out the reaction in one of the two reaction stages using high reactor temperatures or a molar excess of isobutene over methanol. As a result of this, however, oligomerization products of isobutene, dimerization and trimerization, also form in addition to MTBE and, in an undesired manner, a considerable isomerization of the C.sub.4 -olefins in the mixture of hydrocarbons takes place. In any subsequent distillation which may be carried out to isolate 1-butene from the C.sub.4 mixture, the isomerization of 1-butene to 2-butene has the effect of a product loss.
U.S. Pat. No. 4,219,678 does indeed describe a one-stage process for the manufacture of MTBE, in which the working up of the reaction mixture is carried out without the use of auxiliary materials and which does not have the abovementioned disadvantages, such as the formation of oligomerization products of isobutene and isomerization of the unconverted C.sub.4 -olefins, but the maximum isobutene conversion which can be achieved is only about 98.6% so that the residual C.sub.4 mixture (raffinate II) contains more than 1% of isobutene.

Process for the simultaneous manufacture of pure MTBE and a substantially isobutene-free mixture of C.sub.4 -hydrocarbons


A biologically active lipolytic factor having an average molecular weight substantially less than 5000 daltons and comprising active molecular species having molecular weights of about 3000 daltons, 1500 daltons and 700-800 daltons is disclosed. The factor can be isolated, using chromatographic methods, from cachexia-inducing tumours, cultures of tissue cells of cachexia-inducing tumours especially cultures of a MAC16 tumour cell line, or from body fluids such as serum or urine of mammals bearing cachexia-inducing tumours. Cancer diagnostic applications in relation to human individuals are described as well as uses for screening and identifying potential anti-cachetic and/or antitumour therapeutic agents.

For convenience, publications relating to the following description of the background of the invention are numerically referenced and listed in the appended bibliography.
Evidence (see references 1 to 7) has previously been reported indicating that at least some malignant tumours in mammals, especially cachexia-inducing tumours, give rise to the production of one or more catabolic factors which may be found in the circulatory system, e.g. in blood plasma.
It is well known that cachexia, characterised by progressive weakness, dramatic weight loss and wasting, is a common condition arising in many human cancer patients, especially in patients with gastrointestinal or lung cancer, and this often appears to be the most frequent cause of eventual death in such patients. Since, however, cachexia at least in human patients generally arises, often at an early stage, when the tumour mass is only a very small proportion of body weight it cannot be generally explained by a simple competitive effect between the tumour and body tissues for available nutrients; also, although in some cases cancer cachexia is accompanied by anorexia manifested by a severely reduced food and water intake, anorexia does not occur in all cases or appears only after severe loss of weight and body tissues (fat and muscle) has already become established; anorexia cannot therefore be recognised as a primary cause of all or many cancer cachectic conditions, and it seems possible that catabolic factors arising from the tumour and acting more directly on the host tissues may be primarily responsible.
Additionally, there is also some evidence indicating that growing tumours may derive at least part of the fatty acids they require, e.g. for membrane formation, from tissues of their host, and that in at least some cases these fatty acids may be derived from the fats in adipose tissue of the host through the action of a lipolytic catabolic factor that may be found in the host's circulatory system in the presence of the tumour. However, although this may be deemed suggestive of a possible link or causal relationship between such lipolytic factor, other catabolic factors possibly present, the growing tumour, and symptoms of cachexia independent of anorexia, various previous attempts (references 3, 4, 5, 6 and 7) to isolate, identify and characterise a lipolytic factor of this kind have produced somewhat confusing, uncertain, and inconsistent results and there has also been substantial doubt as to the extent of dependence of any such lipolytic factor on tumour specificity.
Thus, in 1980 it was reported by Kitada et al (reference 3) that the serum of AKR mice bearing thymic lymphoma contained a potent lipid mobilizing factor having lipolytic activity as evidenced by comparative in vivo assaying of the breakdown of adipose tissue labelled with radioactive carbon implanted into test animals of which some were injected with samples of the serum, measurements being taken of the radioactive carbon appearing in the respiratory CO.sub.2. The same effects of breakdown of the implanted adipose tissue were also observed upon injecting samples of extracts of the tumours and also upon injecting samples of culture medium from an AKR mouse lymphoma cell culture. These results were also reported again in 1981 (reference 4) by the same investigators, together with the additional result of a similar adipose tissue breakdown effect being observed upon in vivo assaying in the same way a serum sample from a human cancer patient with adenocarcinoma. In addition, the results then reported (somewhat superfically) also included the results of a preliminary attempt to isolate and characterise the active substance by a gel filtration technique involving chromatographing a dilute acetic acid extract of the thymic lymphoma tumour tissue using a Bio-Gel P6 column from which the various fractions were again tested for lipolytic activity by the same in vivo assay technique. It was then deduced from these results that the active lipolytic factor was a small "heat stable" protein having a molecular weight of about 5000 daltons. However, this conclusion was not substantiated by later results (see below) and, in any event, it will be appreciated that use of the in vivo assaying technique did not necessarily exclude the possibility that the test samples injected merely triggered the production of, or activated, a lipolytic factor within the test animal instead of the test samples themselves containing the active lipolytic factor.
Subsequently, Kitada et al reported in 1982 (reference 5) that after continuing their investigations using extracts of thymic lymphoma tumour tissue from AKR mice, using an in vitro technique for assaying lipolytic activity involving the measurement of liberated glycerol after incubation of samples of the tumour tissue extracts with preparations of rat adipocytes, lipolytic activity could only be detected after ageing of the extracts kept at low temperature (4.degree. C.) for several days. Following chromatographic gel filtration of such aged active extracts, whose activity was found to be completely destroyed by digesting with trypsin, they then concluded that the lipolytic active substance which they had detected was formed by aggregation of inactive small protein molecules.
The presence of a lipolytic factor in ascites fluid from DDK mice with sarcoma 180 and in ascites fluid from human cancer patients with hepatoma has also been reported by Masuno et al (references 6 and 7) but in this case their experimental evidence indicated that the lipolytic factor found, termed Toxohormone-L, was an acidic protein of high molecular weight (of the order of 65,000 to 75,000 daltons) which acted indirectly by suppressing food and water intake, thereby promoting anorexia as the main cause of breakdown of adipose tissue and symptoms of cachexia.
Similarly, a macrophage product tumour necrosis factor (TNF) and the homologous or related substance cachectin (see references 10 and 11) which inter alia inhibit lipoprotein lipase activity and induce weight loss have also been implicated as agents concerned in causing cancer cachexia, but again any cachectic effects arising from this source appear to be caused primarily by anorexic effects or dehydration (see reference 12).
It is necessary to recognise, however, that the conditions in experimental animals such as mice and rats bearing tumours of the kind mentioned above may not properly reflect the conditions present in human cancer patients afflicted with cachexia-inducing tumours, especially bearing in mind that in rodents many such tumours grow relatively rapidly and that evidence of cachexia is often apparent, if at all, only at a stage when the tumour has reached a size equivalent to 30-40% of total body weight. In contrast, in humans tumour growth is slower and tumour mass rarely reaches or exceeds 5% of total body weight although symptoms of cachexia often arise whilst the tumour mass is but a small fraction of 1% of total body weight. Nevertheless, there has been a promising development for improving the conditions for experimental investigations following studies more recently reported (references 1 and 2) on mice (pure NMRI strain) bearing a tumour designated MAC16, first described by Cowen et al (see reference 8), of an established series (MAC) of chemically induced, transplantable colon adenocarcinomas, this MAC16 tumour being produced by a particular cell line now deposited on Mar. 8, 1989 in the European Collection of Animal Cell Cultures (ECACC) at the Public Health Laboratory Service Centre for Applied Microbiology and Research, Porton Down, Salisbury, Wiltshire, United Kingdom under a provisional accession number 8903016.
The MAC16 tumour is a moderately well-differentiated adenocarcinoma which has been serially passaged in mice for many years, and it has been found that it appears to represent a more satisfactory experimental model for tumours which induce cachexia in human patients, especially insofar as it has often been found to produce substantial loss of body weight at small tumour burdens (less than 1% body weight) and without a reduction in the intake of either food or water (reference 1).
Some of these recently reported studies (reference 2) have further indicated that the MAC16 tumour in mice gives rise to the production of circulatory catabolic factors, apparently comprising both a lipolytic factor and a proteolytic factor, which seem to be present in the plasma of the tumour-bearing animals and which, it could be postulated, might be directly responsible at least to some extent for the breakdown of the body fat and muscle tissues, and hence for symptoms of cachexia. More particularly, the lipolytic factor was reported as having a lipolytic activity (as measured either in tumour extracts or plasma samples incubated with mouse epididymal adipose tissue followed by use of an in vitro free fatty acid assaying technique) which is non-dialysable, which is destroyed by heat and acid, and which is inhibited by insulin and 3-hydroxybutyrate. However, no more precise characterisation or isolation of this factor was reported, although in a later paper (reference 12) evidence has been presented showing that it is not the same as, and is clearly distinguished from, cachectin or tumour necrosis factor (TNF) referred to earlier.

Biologically active material characterized by catabolic activity generally associated with cachexia-inducing tumors, preparations, production and uses thereof

Cancer Research Campaign Technology Limited


An interlocking rectangular sheet of simulated shakes for lock-up assembly upon a structure in an upwardly directed fashion having a thermo-formed base sheet with an exposure surface and a top and bottom surface. The bottom surface terminates in a cross-sectionally “U” shaped, clipping member. The top surface has a plurality of punched key portions, certain of which having apertured, flanged, assemblies thereon. All of the key portions allow for receiving securing members for attachment of the sheet to the structure, including the flanged portions. The apertured, flanged assemblies and the clipping members cooperate positively to interconnect in the upwardly directed fashion to provide, when secured to the structure by the securing members, a substantial inability to be removed or displaced by weather conditions. The flanged assemblies have an extended “S” shaped configuration. The front and back of each of the sheets have an upward and lower notched portion that provides for longitudinal engagement, one sheet against the other, by way of the front portion engaging the flange, and the rear portion engaging the “U” shaped clip.

Over the years, exteriors of residential homes have been typically sided with materials including asbestos, wood and gypsum boards. Wood siding has come in a number of different forms, including different types of shakes (i.e., a hand-split piece of wood) with an external surface dimension or exposure of 6.5″ to 14″ in height, per shake and an appearance differing in wood grains, textures, and styles. Asbestos siding, now outlawed because of the toxicity associated with the material, was comprised of cement and asbestos fibers, with an exposure of 9″ to 2′ in height. Gypsum boards have been used to simulate wood planking.
Recently, various durable materials have been employed to replace or cover the existing exteriors. Included in such materials have been aluminum, steel, and very recently, fiberglass, polypropylene and vinyl. Fiberglass, for example shown in U.S. Pat. No. 4,015,391 to Epstein, has been short-lived in application because of rotting, thereby decreasing its longevity. Coating materials were ineffective in adherence to the fiberglass. Polypropylene suffers problems in expansion and contraction and in weatherability. Consequently, it is a product that must be painted and then sealed, thereby only providing five (5) years of warranty. ABS materials, another type of plastic, have also been recently introduced, and problems associated with cracking in cold conditions have yet to be overcome.
Accordingly, the current material of choice is polyvinyl chloride, or "PVC" with added composites to create texture, and to improve weatherability for longer lasting applications.
Siding, when applied, must secure first to the exterior of the house, and second the pieces must secure to one another. Typically a starter strip or course is first applied. Then, a sheet is attached to the starter strip and nailed to the house. Subsequent sheets must thereafter interlock to one another, in one of two possible ways. First, a "lock-up" assembly can be employed in which the interlocking occurs by way of an upwardly-directed motion. Second, a "stacking" arrangement can be employed by which the interlocking occurs by way of a downwardly-direction motion. It is generally recognized in the art that the "lock-up" assembly is preferred because assembly is quicker, and presents less stress to the attached panel as a subsequent panel is being upwardly locked in place.
The siding business has been replete with the purported inventions of others.
For example, U.S. Pat. No. 3,417,531 to Jones shows a lock-up assembly for siding having beads and legs for attachment. Jones does not show a clipping assembly, and thus suffers from impractical difficulty in detachment after the paneling is applied.
U.S. Pat. No. 3,703,795 to Mattes shows a two piece assembly system wherein a second piece (see, e.g., "retainer part" 84), separate and apart from the first piece, must be applied after the first piece is applied to retain the portions, and provide a lip for the subsequent sheet to be locked in place. Consequently, this discontinuous design is slow in assembly, and because of the two piece application, would generally be effective only where the exterior of the house has been configured with gypsum board or with the addition of a backing board.
U.S. Pat. No. 4,186,538 to Marcum, Jr. shows a metal-specific application that typically cannot be used for plastics including PVC because the upward surface of the "hooks" 13 are rolled. While metal can be deformed easily in this manner, to do so with plastics would be cost prohibitive. Moreover, as can be observed in Marcum, Jr.'s disclosure, there is no nailing or fastening means integral to the hooks 13, and thus hooks 13 are not engaged to the backing or exterior of the house. Accordingly, where a seem is first confronted by a hook 13 of a panel, there will be no engagement, and thus the entire sheet is likely to visibly detach after a short duration of use. Lastly, the clips are not displaced relative to the cross-section of the sheet, thus minimizing the ability to create an external surface texture of the siding.
U.S. Pat. No. 4,308,702 to Rajewski addresses the issue of rolling the upward surface, as shown in Marcum, Jr., by rolling a plastic piece along fold line 50. However, plastic manufacturing does not permit such heating and rolling without sacrificing flexibility and durability at the point of the fold. In other words, the sheet is first extruded, and then thermo-formed at the point of the fold and folded upon itself, it is also folded so as to provide the flange. Such two step heating is more expensive, and the result is less flexible and durable. As a result, in operation, the sheet so folded will be more liable to crack along the fold line 50, or worse, at the flange 26, and thus be in need of more frequent replacement. Additionally, flange 26 in Rajewski is co-continguous with the entire sheet, thus requiring the use of more material than is necessary to achieve the same or a better result. Reduction in the amount of material results in lower costs, and hence greater profits.
U.S. Pat. No. 4,450,665 to Katz shows an extruded panel having a flange 135 for engaging an upwardly locking lip 150 having a bead 154. Katz is important in showing a way of having a positive engagement click resulting from the specific shapes involved. However, the nailing step as shown in FIG. 7 of Katz does not provide a double thickness through which the nail must pass. Rather, it is a single thickness and the flange depends therefrom, leaving a point of natural failure at the dependent connection when the sheets are placed under wind load. Also, like Rajewski, the flange of Katz is continguous with the entire length of the panel, and thus suffers from extra material costs.
U.S. Pat. No. 4,669,238 to Kellis, et al. shows a discontinuous clip assembly. However, like in Mattes, Kellis, et al. provides a clip that is nailed as a separate stage, and can be placed by the installer at any location chosen. First, it must be observed that whenever the installer is given the option to "cut corners" in installation, the installer will. Accordingly, in operation, Kellis, et al. will eventually result in sheets that are not bound at specific distances (e.g., every 4″) and thus the installation will be weaker. Also, the additional clip portion when added will only result in a single thickness that is nailed to the backing. Additionally, in the locations in which clips are not used, there is the natural tendency for sagging and bowing because of the obvious distance between the upper and lower interlocking pieces. Thus, in operation, Kellis, et al. is less than desirable.
U.S. Pat. No. 4,864,787 to Bukowski shows a double bend in the flange, thus suffering from some of the same problems indicated above. Additionally, Bukowski nails into a singe thickness, which also indicates a point of weakness. It should be appreciated that Bukowski appears to deal with the issue of edges and how sheets can connect without the need for a separate edge to be applied. This extra complication has found limited use in the industry.
U.S. Pat. Nos. 5,072,562; 5,249,402; 5,347,784 to Crick, et al. show a stack-locking mechanism, and, importantly, shows that the industry is replete with simulating the surface shakes in a manner in which each shake is identical, and the spacing between each such surface shake is identical. In this manner, the industry has heretofore only provided a simulated appearance that is so unnatural as to show that it is, in fact, not real. Apparently, heretofore no one addressed the need to vary the thickness of the lines between shakes so as to create an uneven effect more consistent with the natural material, and also to improve the shading effect.
U.S. Pat. No. 5,537,792 to Moliere shows a lock up assembly formed from a single mold, in which the nailing portion is a single thickness, the flange 40 provides a narrow opening for insertion of the interlock lip 50, and the distance between shakes, i.e., the thickness of the vertical lines between shakes, is always the same.
It is thus an object of the instant invention to provide a lock-up assembly in which the locking of the interlock lip from each lower portion of a sheet is allowed a greater entry aperture then the locking the aperture for a more positive locking effect, the nailing thickness is double the traditional thickness in that nails attach both the flange portion as well as the back portion to the backing material, and the vertical lines between shakes vary to resemble more of a natural appearance.
It is an additional object of the instant invention to provide nailing substantially co- linear with the topward portion of the interlock between the lip and flange, to thereby minimize wind distortion effects.

Fully interlocking synthetic, simulated shake siding


An electrowinning process for the recovery of various metals including copper, zinc and nickel from an aqueous electrolyte in an electrolytic cell containing anodes and cathodes is disclosed wherein the anodes are formed from a lead alloy containing from about 0.05% to about 0.25% by weight strontium. The lead alloy for the anodes also preferably includes from about 0.005% to about 0.1% by weight aluminum alone or in further combination with either about 0.1% to about 5.0% by weight tin or at least 0.01% by weight silver, the lead alloy anodes having a hard, adherent oxide surface layer preferably formed in situ within the electrolytic cell.

The present invention relates to an electrowinning process for the recovery of one of a plurality of metals from an aqueous electrolyte and more specifically to such a process carried out within an electrolytic cell containing spaced apart anodes and cathodes with the anodes being formed from lead or a lead alloy.
Electrowinning processes are widely employed for recovering one of a number of metals from an aqueous electrolyte solution containing ions of the particular metal. Metals suitable for refining by electrowinning processes include, but are not limited to copper, zinc, nickel, antimony, cadmium, chromium, cobalt, manganese and silver. The electrolyte solution is typically placed within an electrolytic cell containing spaced apart anodes and cathodes which are commonly arranged in alternating order. The electrolyte may be a solution of sulfates, sulfides, caustic or nitrates depending upon the particular metal to be refined by electrowinning. During operation, an electrical potential is formed between the anodes and cathodes in order to cause the metal ions from the aqueous electrolyte to deposit upon the cathodes by conventional electrolysis.
In electrowinning processes of the type summarized above, the aqueous electrolyte solution, containing sulfuric acid, in the electrowinning of copper, for example, tends to corrode the surface of the anodes. When the electrowinning process is continued over long periods of time, corrosion not only results in the introduction of lead from the anodes as an impurity in the metal deposited upon the cathode but also results in destruction of the anodes themselves. This in turn disrupts the electrowinning process and requires costly replacement of the relatively massive anodes.
In the prior art, various alloys have been employed for forming such anodes in an attempt to resist corrosion of the type referred to above. One of the earlier replacements for pure metallic lead in the anodes was an alloy formed from lead in combination with antimony. Later, the use of lead-calcium alloys as inert anodes in electrowinning processes for the recovery of copper was disclosed for example by U.S. Pat. No. 3,859,185 issued Jan. 7, 1975.
However, even with the use of such alloys, corrosion has continued to be a problem in electrowinning processes for the recovery of metals such as copper. Accordingly, in view of increasing requirements for various metals subject to refining by means of electrowinning, there has been found to remain a need for an improved electrowinning process employing an insoluble anode and more particularly for such an improved electrowinning process carried out in an electrowinning cell containing spaced apart anodes and cathodes.


A package comprising: a receptacle comprising front and rear walls joined to each other at top and bottom cross seals and connected to each other along first and second sides of the receptacle, the front wall comprising a loop that projects outward and that extends across the front wall from the first side to the second side of the receptacle; and a pair of zipper strips having mutually interlocked profiles, the zipper strips being disposed inside and joined to the loop.

The present invention relates to reclosable plastic bags of the type in which food products, such as chips and cereal, and other goods are packaged for sale to consumers. More particularly, the present invention relates to reclosable plastic bags manufactured and filled on form-fill-seal (FFS) machines, wherein a series of interlocked plastic zipper strips are attached at bag-length intervals transversely to the longitudinal axis of the thermoplastic film material used to form the reclosable bags on the FFS machine.
The present invention relates to improvements in the package-making art and may be practiced in the manufacture of thermoplastic bags and packages of the kind that may be used for various consumer products, but which are particularly useful for food products which must be kept in moisture and air-tight packages, free from leakage until initially opened for access to the product contents, which packages are then reclosable by zipper means to protect any remainder of the product therein. The prior art is fairly well-developed, but nevertheless remains susceptible to improvement contributing to increased efficiency and cost effectiveness.
One problem that accompanies reclosable packages produced from a continuous supply of thermoplastic film material on FFS machines is the difficulty in attaining a satisfactory sealing of the bag or package against leakage, particularly where the zipper and area of film engaged by the zipper extends through the side (cross) seal areas separating one bag or package from the next. This problem occurs where the zipper is attached parallel to the longitudinal axis of the thermoplastic film material used to form the reclosable bags on the FFS machine, in which case the transverse, or side, sealing bars must flatten and seal the zipper at the same time they are sealing the thermoplastic film from which the packages are being made. It is difficult to consistently and successfully make leakproof packages using this technique unless the zipper ends have been spot sealed at the cross seal location in an earlier operation.
In addition, the length of reclosable packages made on FFS machines wherein the zipper is attached parallel to the longitudinal axis of the thermoplastic film is limited to the diameter of the filling tube of the FFS machine. Thus, generally bags of this type are wider than they are long. While such bags are suitable for certain products where shorter bags are desirable, such as cheese and chicken parts, these bags are not suitable for applications in which longer bags are desirable, for example, chips and other snack foods.
Among the approaches taken to solve these problems has been the substitution of a transverse zipper for the longitudinal zipper. A method and apparatus for making reclosable bag material and reclosable bags on an FFS machine utilizing transverse zippers is disclosed in U.S. Pat. No. 6,017,412.
When a transverse zipper is provided, the cross-sealing bars associated with the FFS machine do not flatten the zipper profile during formation of the top and bottom seals of the package since the transverse sealing bars may seal the zipper to the thermoplastic sheet material transversely thereacross without contacting the zipper profile. In addition, when a transverse zipper is used, the length of the packages made on the FFS machine can be varied without varying the length of the transverse zipper segment and is not limited to the diameter of the filling tube.
There is a continuing need for improvements in methods of manufacturing reclosable packages using an FFS machine wherein zippers are transversely applied to a web of packaging material before it enters the FFS machine.

Reclosable package having zipper disposed within loop on front wall


A multi-band antenna assembly, comprising: a first antenna used for wireless local area network and comprising a first radiating element comprising a high frequency radiating portion and a low frequency radiating portion, and a first grounding element adapted for assembling said first antenna on an electric device; a second antenna used for wireless wide area network and comprising a second radiating element comprising a high frequency radiating portion and a low frequency radiating portion, and a second grounding element adapted for assembling said second antenna on an electric device; wherein said first antenna and said second antenna independent from each other; said grounding elements of said two antennas comprising two main bodies substantially aligned with each other, said first and second radiating elements of said first antenna and said second antenna locating on the same side of said first and second grounding elements, said low frequency radiating portions of said first antenna and said second antenna extend more than directions.

1. Field of the Invention
The present invention relates generally to a multi-band antenna assembly, and more particularly to a multi-band antenna assembly used in electric devices such as notebook, and used for both Wireless Local Area Network (WLAN) and Wireless Wide Area Network (WWAN).
2. Description of the Prior Art
As communication technology is increasingly improved, the weight, volume, cost, performance, and complexity of a communication system also become more important, so antennas that transmit and receive signals in a wireless communication system especially 'draw designers' attention. In a wireless local area network (WLAN), because the space for setting up an antenna is limited and the antenna should transmit a large amount of data, the antenna should be carefully designed. In addition, to meet the requirement of compact size, the antenna is needed to be able to transmit signals of all WLAN bands, including 802.11b (2.4 GHz) and 802.11a (5.2 GHz).
Referring now to FIG. 1, a multi-band antenna 10 is shown and includes a first antenna 11 (WLAN), a second antenna 12 (WWAN), and a grounding element 13 used by the first antenna 11 and the second antenna 12 commonly. The multi-band antenna 10 is a combination of the WLAN antenna and the WWAN antenna together to save space. However, the first antenna 11 of the multi-band antenna 10 is integrated with the second antenna 12 to form a whole. So this multi-band antenna 10 is inconvenient to replace one of the first antenna 11 and the second antenna 12 which is useless. Antennas 11,12 are broken, it must exchange the whole antenna 10, which is wastely and inconvenient.
Hence, an improved multi-band antenna assembly is desired to overcome the above-mentioned shortcomings of the existing antennas.


An active RF transponder is provided with a wake-up circuit that wakes the RF transponder from a sleep state upon detection of an RF interrogating signal. The active RF transponder includes a battery, an antenna adapted to receive RF signals from an interrogator, and electronic circuitry providing the various RF transponder functions of sending/receiving signals and storing data. A first embodiment of the invention includes a wake-up circuit that periodically checks for the presence of an RF signal at the antenna. The wake-up circuit is coupled to the antenna and includes a switch adapted to selectively couple the battery to the electronic circuitry and provide electrical power thereto upon detection of the RF signals by the antenna. The wake-up circuit further comprises an oscillator providing a clock signal having a low duty cycle that defines intervals during which the antenna is sampled for presence of the RF signals (e.g., approximately 20 ns every 100 xcexcs). A second embodiment of the RF transponder includes a wake-up circuit as in the first embodiment that is further adapted to detect a code sequence modulated in the RF signals. The code sequence is unique for a class of RF transponder, so the wake-up circuit can discriminate between interrogating signals. A third embodiment of the RF transponder includes a wake-up circuit that wakes the RF transponder upon detection of an RF signal that contains data within a desired band of frequencies. This embodiment enables the RF transponder to discriminate between RF signals that likely contain valid data and other RF noise. After the RF transponder has been waked, the wake-up circuit returns the RF transponder to a sleep state if valid data is not detected within a predetermined period of time.

1. Field of the Invention
The present invention relates to radio frequency (RF) transponders and radio frequency identification (RFID) systems, and more particularly, to a battery-powered RF transponder having a xe2x80x9cwake-upxe2x80x9d circuit that turns on the RF transponder circuitry upon detection of an interrogating signal from an RFID interrogator.
2. Description of Related Art
In the automatic data identification industry, the use of RF transponders (also known as RF tags) has grown in prominence as a way to track data regarding an object on which an RF transponder is affixed. An RF transponder generally includes a semiconductor memory in which information may be stored. An RF interrogator containing a transmitter-receiver unit is used to query an RF transponder that may be at a distance from the interrogator. The RF transponder detects the interrogating signal and transmits a response signal containing encoded data back to the interrogator. RF and RFID systems are used in applications such as inventory management, security access, personnel identification, factory automation, automotive toll debiting, and vehicle identification, to name just a few.
Such RFID systems provide certain advantages over conventional optical indicia recognition systems (e.g., bar code symbols). For example, the RF transponders may have a memory capacity of several kilobytes or more, which is substantially greater than the maximum amount of data that may be contained in a conventional one-dimensional bar code symbol. The RF transponder memory may be re-written with new or additional data, which would not be possible with a printed bar code symbol. Moreover, RF transponders may be readable at a distance without requiring a direct line-of-sight view by the interrogator, unlike bar code symbols that must be within a direct line-of-sight and which may be entirely unreadable if the symbol is obscured or damaged. An additional advantage of RFID systems is that several RF transponders can be read by the interrogator at one time.
RF transponders may either be xe2x80x9cactive,xe2x80x9d in which they include an internal power source (i.e., battery), or xe2x80x9cpassive,xe2x80x9d in which they do not include a battery and derive their energy entirely from the interrogating signal provided by the RF interrogator. The active RF transponders generally have a greater transmitting range than passive transponders, but have the associated disadvantage of greater bulk due to the inclusion of the battery. The operational life of an active RF transponder is dependent upon the capacity of the battery, and it is generally desirable that an RF transponder have as long an operational life as possible (e.g., longer than five years). Even though the circuitry of the RF transponder draws relatively low current, the battery will quickly run down if the circuitry is powered up continuously. To conserve the battery power, the RF transponder may be placed in a low power (or xe2x80x9csleepxe2x80x9d) mode in between operations. When the RF transponder is interrogated, the RF transponder must then be xe2x80x9cwakedxe2x80x9d or restored to an operating mode from the sleep mode.
A drawback of this type of operation is that the interrogating signal must typically be above a certain threshold level (e.g., greater than 100 mv) in order to generate sufficient current to be detected. Another drawback is that the wake-up circuit itself draws current that runs down the battery. Yet another drawback is that the wake-up circuit is not sufficiently selective, and, as a result, it tends to wake the RF transponder whenever any RF signal is detected. In certain applications, plural passive and active RF transponders may be disposed in close proximity to each other, and it would therefore be desirable to selectively wake only specific ones of the RF transponders while allowing other ones of the RF transponders to remain in the sleep mode.
Accordingly, it would be very desirable to provide a wake-up circuit for an active RF transponder that can be operated with very low current, and which can detect an interrogating signal having very low power (e.g., less than 100 mv). In addition, it would be highly desirable to provide a wake-up circuit that can selectively respond to an interrogating signal having a particular pattern so that only a particular RF transponder is waked.
In accordance with the teachings of the present invention, an active RF transponder is provided with a wake-up circuit that wakes the RF transponder from a sleep state upon detection of an RF interrogating signal. The active RF transponder includes a battery, an antenna adapted to receive RF signals from an interrogator, and electronic circuitry providing the various RF transponder functions of sending/receiving signals and storing data.
A first embodiment of the invention includes a wake-up circuit that periodically checks for the presence of an RF signal at the antenna. The wake-up circuit is coupled to the antenna and includes a switch adapted to selectively couple the battery to the electronic circuitry and provide electrical power thereto upon detection of the RF signals. The wake-up circuit further comprises an oscillator providing a clock signal having a low duty cycle that defines intervals during which the antenna is sampled for presence of the RF signals (e.g., approximately 20 ns every 100 xcexcs). The wake-up circuit further comprises a comparator that compares the detected RF signals to a threshold value in accordance with the clock signal and signals the switch to couple the battery to the electronic circuitry upon the detected RF signals meeting the threshold value. After the switch has coupled the battery to the electronic circuitry, the switch becomes uncoupled upon either detection that the RF signals have dropped below a threshold for a predetermined period of time, or upon detection that receipt of a message encoded in the RF signals has completed.
A second embodiment of the RF transponder includes a wake-up circuit as in the first embodiment that is further adapted to detect a code sequence modulated in the RF signals. The code sequence is unique for a class of RF transponder (e.g., battery powered RF transponders), so the wake-up circuit can discriminate between interrogating signals. This embodiment permits the RF transponder to operate within the vicinity of passive RF transponders since only the intended class of RF transponders that correlate with the code sequence modulated in the RF signals will be waked. The battery becomes uncoupled from the electronic circuitry by operation of the switch if the detected code sequence fails to correlate with a predetermined code sequence that is unique to the class of RF. transponders. The wake-up circuit oversamples the RF signals to detect the code sequence modulated therein.
A third embodiment of the RF transponder includes a wake-up circuit that wakes the RF transponder upon detection of an RF signal that contains data within a desired band of frequencies. This embodiment enables the RF transponder to discriminate between RF signals that likely contain valid data and other RF noise. The wake up circuit further comprises an oscillator providing a clock signal having a low duty cycle that defines sampling intervals during which rising or falling transitions of data signals recovered from the RF signal are counted. If the number of transitions that are detected during two successive sampling intervals falls within a desired range (i.e., corresponding to a desired frequency band), the wake-up circuit wakes the RF transponder. After the RF transponder has been waked, the wake-up circuit returns the RF transponder to a sleep state if valid data is not detected within a predetermined period of time.

Active RF tag with wake-up circuit to prolong battery life


Various embodiments are disclosed relating to beacon transmissions in wireless networks. In an example embodiment, a wireless node may receive a beacon from one or more wireless nodes. The receiving node may generate and transmit a beacon map to other wireless nodes in the network. The beacon map may provide information relating to one or more of the received beacons, such as a time stamp or other time information for the beacon and the originating wireless node for the beacon, such as an address of the originating wireless node. In an example embodiment, the beacon map may be transmitted upon request or within a beacon, or within another message. In another example embodiment, a beacon map may be received at a receiving wireless node, including information relating to beacons from one or more other wireless nodes. A status of at least one of the beacons may be determined based upon the beacon map.

The rapid diffusion of Wireless Local Area Network (WLAN) access and the increasing demand for WLAN coverage is driving the installation of a very large number of Access Points (AP). Though the cost of APs is traditionally not very high, the deployment of APs often involves connecting the AP through a wired connection (traditionally Ethernet), and this introduces complexity and high costs for deployment in certain locations.
The concept of a wireless meshed network of APs or other wireless nodes is being developed. The nodes within one meshed network may in some cases operate at the same frequency. This means that for such systems, in contrast to commonly deployed WLAN systems today, several APs in such meshed network may transmit their beacon messages in the same channel. This may result in the collision of beacon messages and can be very inefficient, since in the currently deployed WLAN standards (such as IEEE 802.11b) no contention resolution is provided for beacon messages. Rather, each AP may transmit its beacon message after an Inter-frame Space (IFS) since the previous data transmission has ended. In such case, a beacon collision from the two APs will very likely result.

Beacon transmission for wireless networks


A chain propelled belt conveyor having a centrally mounted single strand of roller chain. The roller chain drives the belt and supports the belt along the upper load carrying run of the belt. Pairs of conveyor trolleys support the central portion of the belt about the return non-load carrying run of the belt. A track having a horizontal rail extending between a pair of opposed C-shaped channel sections is used to guide the roller chain assembly.

I. Field of the Invention
The present invention is directed to a chain propelled belt conveyor having a centrally mounted drive and guidance assembly and, more particularly, to a drive and guidance assembly for a belt conveyor having a single roller chain.
II. Description of the Relevant Art
Chain driven belt conveyors for transporting materials are well known. These conveyors typically utilize a pair of motor driven sprockets to propel a pair of chains affixed to an endless belt. The pair of chains are connected to an underside of the belt. Each chain slides in a track which is formed to guide the chains between the sprockets. However, the sliding of the chains in the tracks causes significant wear on the chains and also results in a significant power loss to the conveyor system. A further disadvantage of this type of conveyor system is that the chains frequently exert unequal pull on the opposite sides of the belt.
Also known are chain driven belt conveyor systems utilizing a series of pivotably interconnected load carrying sections. Each section is supported for movement along the conveyor by a truck. The trucks are interconnected by a single chain. Each truck has a pair of end flanges extending from a transverse base. One of a pair of wheels is mounted to each flange to rotate about a vertical axis. The pair of wheels travel in a track section to guide the truck along both the upper run and lower run of the conveyor system. A vertically aligned shaft extends from the base between the flanges of the truck In support a central roller. The central roller is mounted to rotate about a vertical axis in a U-shaped guide rail of the track. However, such a conveyor system requires a large and complicated truck, as well as a special track. Accordingly, such a system is expensive to produce.
Traditional known troughed belt conveyors are known for holding certain materials, such as particulate matter. However, troughed belt conveyors require a large radius of curvature between the upper run and lower run. Accordingly, only chain conveyors or a flat belt with accordion-profile vertical edge are used in confined spaces. However, dual chain conveyors require clearance between the conveying bed and side wall or skirt enclosures.


Techniques (200) and apparatuses (102, 800) for gesture-enabled settings are described. In some embodiments, a gesture manager (112) is configured to enable selection (202) to enter a settings mode during presentation of a user interface (120), responsive to selection indicate (204) that the user interface is in the settings mode, enable (206) selection to alter a setting through a gesture made to a label in the user interface, and alter (210) the setting responsive to the selection.

Current techniques for altering settings on a computer can be cumbersome. Users wishing to alter a setting often begin at a home screen, then select another screen or toolbar having various selectable icons, find an icon associated with settings, tools, or options, select that icon to bring up another screen, and then search through this third screen to find the desired setting to alter. Sometimes, simply getting to this final settings screen is cumbersome. Further, finding the desired setting within a settings screen can itself be cumbersome, as it may require searching through many entries for different applications or functions of the computer associated with the setting.


A video camera comprising a taking lens, an image taking circuit which generates a video signal by receiving a light having passed through the taking lens, a knee correction circuit which compresses a video signal generated by the image taking circuit and having a level as high as or higher than a predetermined level, a detection circuit which detects a luminance distribution condition of a field, a pedestal adjusting circuit which adjusts a black level of the video signal generated by the image taking circuit and a control circuit which changes a compression method of a video signal in the knee correction circuit and an adjusting method of the black level in the pedestal adjusting circuit according to a luminance distribution condition of a field detected by the detection circuit. According to the present invention, it is possible to perform various controls in response to a luminance condition of a field.

1. Field of the Invention
The present invention relates to a video camera. More specifically, the present invention relates to a video camera which performs various controls according to a luminance condition of a field.
2. Description of the Prior Art
FIG. 1 is a block diagram of a prior art.
In FIG. 1, 1 is a taking lens system. 2 is an infrared ray cut filter, which cuts infrared ray that cannot be seen by the human eye, causes a noise, and interferes with a photographing. 3 is an iris. 4 and 5 are color separation prisms; 4 leads only green light to a G-charge coupled device (hereinafter charge coupled device will be referred to as CCD)6, and 5 leads mazenta light having passed through the prism 4 to a R/B-CCD7. The light having passed through the prism 4 enters the G-CCD6; a luminance signal of the green light is detected by the entire picture elements of the G-CCD6 which outputs a signal G relating to the entered green light. The light having passed through the prism 5 enters the R/B-CCD7, which detects red light and blue light with a corresponding picture element, respectively, and outputs signals R and B relating to the entered red and blue light as separate signals. The signals of G, R, and B detected by CCDs 6 and 7 are converted into video signals after the noises are reduced by a well-known correlation double sampling (hereinafter referred to as CDS) circuit 8, respectively. After the noises are further reduced at a low pass filter (hereinafter referred to as LPF) circuit 9, the video signals of G, R, and B are amplified to an appropriate intensity at an auto gain control (hereinafter referred as AGC) circuit 10, and are clamped to a predetermined level in a clamp circuit 11. 12 is a white balance circuit, which adjusts white balance in response to a color temperature by adjusting the gain of R and B channel.
13 is a pedestal adjusting circuit, which maintains a black level of the video signals at a predetermined level (blanking level), to be more specific, adds a bias voltage to an input signal so that an output signal becomes zero when an input signal becomes zero.
A gamma correction circuit 14 corrects a gamma value in accordance with the characteristics of a TV receiver. A knee correction circuit 15 has input/output characteristics shown with a solid line in FIG. 13.
16 is a matrix circuit, which generates a luminance signal Y and color difference signals R-Y and B-Y from the R, G, and B signals. Thereafter, the color difference signals R-Y and B-Y are balanced-modulated in a modulation circuit 17, and then they are added to each other at an adder 50, and thereafter a color burst signal is added to them at an adder 51 to form a chrominance signal. Then, at an adder 53, they are added to a luminance signal Y to which a synchronizing signal has been added at an adder 52, and are outputted as composite video signals.
18 is a non additive mixing (hereinafter referred to as NAM) circuit as shown in FIG. 3, which inputs the signals of each of R, B, and G channels of the CDS circuit 8 and outputs only a signal having a maximum value of the R, B, and G signals.
41 is a detection circuit which smoothes a signal outputted by the NAM circuit 18.
An iris driving circuit 21 controls the iris 3 so that the level of a signal detected by the detection circuit 41 becomes constant.
When a rearlight correction switch 40 is closed, a predetermined value is added to the outputs of the detection circuit 41 at the adder 29. Therefore, in this case, the iris 3 is opened wider than when the control is performed based on only the output of the detection circuit 41, so that the taken image of the main subject against the light becomes brighter.
To improve the reproducibility of a luminance, a knee correction circuit 15 compresses a luminance difference of a wide dynamic range into that of a narrow dynamic range which can be reproduced on a TV screen. The compression is performed by compressing a gradation of a high luminance area. Since the obtained luminance difference of a video signal differs according to the luminance distribution condition of a field, it is preferable to change the compression method according to the luminance distribution condition. However, in the gradation compression method of the conventional knee correction circuit 15, for example, as shown by a solid line in FIG. 13, the range with an input signal intensity of 100% to 300% is set to be compressed into a range with an output signal intensity of 100% to 120%. In addition, the gradation compression starting point and the compression rate are fixed, respectively. However, since the luminance difference between a main subject and the background largely differs according to a field condition, with only one compression method, it is difficult to correct a reproduction gradation and therefore the reproduction gradation deteriorates. Especially, in a shooting of a scene including a main subject against the light or a main subject illuminated against the dark, for example, a person directed a spotlight, the above problem is arisen. There is another well-known gradation compression method in which a gradation compression starting point decreases as a peak value of a video signal increases. However, this method also cannot cope with a shooting of a scene including a main subject against the light or a main subject illuminated against the dark since the gradation compression is not changed according to a luminance distribution condition of the field.
Since the iris 3 is closed in by the iris driving circuit 21 when the average luminance of the field is high, a main subject becomes black in a shooting of a scene including the main subject against the light due to an insufficient exposure. To prevent this, the iris 3 is adjusted based on the main subject in a shooting of a scene including the main subject against the light. Even in this case, the light from the background intrudes into the main subject because of a light reflection on a lens surface, etc. and the subject becomes whitish, so that the image becomes less clear. For example, as shown in FIG. 11A, when a black subject is shot against the light, the center of the image plane where a main subject is situated becomes black and its surroundings where the background is situated becomes bright. However, since an internal reflection of an optical system causes a flare to increase a luminance of a subject image, the luminance level of the subject is increased by the flare, as shown in FIG. 11C, by the amount Vf more than the actual luminance level (black level) Vd shown in FIG. 11B. In correcting such a phenomenon, an excellent reproducibility of an image cannot be attained only by opening the iris 3 according to a luminance of a main subject.
The iris driving method comprising an average detection by the detection circuit 41 is directed to a control by which the average brightness of an entire image plane becomes an optimal luminance. In other words, the iris 3 is controlled so that a detection voltage of an image plane where the total area of high light parts is the same as that of black parts becomes a predetermined reference value. However, according to this method, an output of the image sensor (CCD) is apt to decrease, for example, in shooting an image plane of single color. As a result, the Signal to Noise (hereinafter referred to as S/N) ratio deteriorates. Another iris driving method is to use a peak detection. In this method, the output of the image sensor relating to an image of single color can be increased. However, since the iris 3 is controlled according to a maximum peak value regardless of the size of the area having a peak level, even when a high luminance part is in a small area, the iris is controlled according to a luminance level of the high luminance part in the small area. Consequently, the signal level in the wide area becomes low and therefore the entire image plane becomes dark, which deteriorates the S/N ratio.
A video camera usually shoots a frame of an image plane at every 1/30th of a second. To prevent flickers on a TV screen, an image plane for one frame is interlace-scanned: the image plane is divided into two image planes (fields), each field is scanned in 1/60 second, and a frame of a complete image plane is composed of two fields. When a CCD is employed as an image sensor, there are two methods, that is, a field accumulation mode and a frame accumulation mode, to obtain a video signal constituting the two fields. In the frame accumulation mode, the image of A and B fields are alternately shot. Here, A field is defined as a field consisting of odd scanning lines and B field is defined as a field consisting of even scanning lines. In a field accumulation mode, a field is constituted by combining two vertically adjoining image element signals into one image element signal. The images of the A field and the B field are alternatively shot by differentiating the combination of the adjoining picture elements by vertically shifting them as shown in FIG. 17 so that the images of the A and B fields obtain the same effect as the effect that of the image obtained by an interlace scanning. In the field accumulation mode, since the output signal of each image element is derived for 1/60 second, the light charge accumulation time is half that of the frame accumulation mode. Consequently, a dynamic range can be doubled.
However, in a place where there is only a little incident light, since the accumulation time is short, the S/N ratio is inferior to that of the frame accumulation mode, and the image quality deteriorates. In addition, since the output of each image element in response to the same quantity of the incident light is half that of the frame accumulation mode, the outputs of two vertically adjoining picture elements is combined to obtain a video signal having the same level as that of the frame accumulation mode. Consequently, a vertical resolving power decreases. On the contrary, in the frame accumulation mode, since a horizontal scanning line on an image plane is composed of an output of a picture element line in a horizontal line of a CCD, a vertical resolving power is superior to that of the field accumulation mode. However, since the light charge accumulation time is twice that of the field accumulation mode as described above, a subject luminance at which an accumulation electric charge starts to overflow is half that of the field accumulation mode, so that the dynamic range becomes narrow. Consequently, when a luminance difference is small, for example when a shooting is performed in a lighting from the front or in a room, by using the frame accumulation mode, an image signal with an excellent reproducibility is obtained. When a luminance difference is large, for example when a shooting is performed against the light, outdoors where there is a shade, or indoors where the background includes an outdoor view (high luminance part), by using the field accumulation mode, an image signal with an excellent reproducibility is obtained.
However, conventionally, the above-described mode selection has not been adopted; a shooting mode has been fixed in each type of a video camera, respectively.
In a video camera, to obtain a clear image plane, the brightness of an entire image plane is so controlled as to be maintained at a predetermined level by an iris and an AGC circuit, etc. That is, a signal with the greatest intensity of the video signals R, B, and G is selected at a NAM circuit 18, and then the selected signal is smoothed at a detection circuit 41. By the smoothed signal, the iris 3 is controlled through the iris driving circuit 21 so that the smoothed signal maintains a fixed intensity. However, such control method has a disadvantage that a main subject becomes dark under a shooting against the light because the background (high luminance part) largely affects the brightness of a projected image. Moreover, if the rearlight condition is corrected by only an amplification control of the AGC circuit, the CCD operates at a low level with respect to a subject against the light. Consequently, the S/N ratio with respect to a main subject deteriorates because an operation level of the CCD is not controlled by the iris 3, even if the CCD could be operated at a sufficiently high level with the iris opened to its opened end.

Video camera having a video signal processing apparatus


Provided is a set of techniques for measuring different properties or parameters of liquid crystal mixtures by applying a driving waveform and measuring the response current and/or the optical response. This may be done by using specific liquid crystal test cells. Also provided are the optimized test cell parameters that are used in the algorithms for calculating the properties.

The disclosure herein relates generally to techniques and equipment that may be used in conjunction with measuring liquid crystal parameters and ion impurities.
Liquid crystal materials used in modern LCD displays, LCD TVs, and so forth, are typically a mixture of a plurality of different individual liquid crystal components. Ion concentration, twist elastic constant (K22), and rotational viscosity (γ1) are three very important parameters for the study of LC materials/mixtures and for LCD manufacture. Although there are many publications and patents regarding techniques for LC material property measurement, they are either too simplified to provide reliable and repeatable results, not sensitive enough for advanced LC materials and LCD processes to allow for the reliable and accurate detection of ultra-low ion concentrations, or overly complex.
What is needed, therefore, is a design that is better able to meet such challenges.

Measurement techniques for ion impurities in liquid crystal mixtures


A pneumatic tire of the invention includes: a stepped-shaped raised area provided in the main groove positioned at a center area of the tire so as to be continued circumferentially of the tire, connected to either the main groove walls, and raised from the groove bottom; and a ridge lower than a tread surface of the tire in each of the main grooves on both outsides of the main groove at the center area of the tire so as to be raised from the center of the groove bottom continuously along the length thereof without being joined with the groove walls, and the angle of inclination of the main groove walls with respect to the normal line of the tangential line on the tread surface of the main groove portion is parallel to each other or is 5° or smaller.

1. Field of the Invention
The present invention relates to a pneumatic tire having a rib pattern including a plurality of land portions continuing substantially circumferentially of the tire and, more specifically, to a pneumatic tire having a rib pattern which improves wear resistance, improves stone-nipping resistance, prevents generation of cracks on the groove bottom, and secures braking property and driving property when having worn.
2. Description of the Related Art
Uneven wear of a pneumatic tire having a rib pattern mainly includes step wear starting from grounded ends in the direction of axis of rotation of the tire and river wear generating at rib ends on both sides of a main groove, and there is a problem in the related art that particularly the river wear which is uneven wear occurring locally in the circumferential direction at the rib ends tends to occur.
An effective countermeasure for the step wear is to prevent the uneven wear by providing circumferential narrow grooves in the vicinity of the grounded ends of the shoulders of a tread surface. Also, in order to cope with the river wear, a technology to form a number of short sipes arranged along the rib ends circumferentially of the tire so as to extend widthwisely of the tire and open at one end into the main groove is known.
On the other hand, the rib pattern has a problem that it tends to nip stones in the groove, and the nipped stone is firmly held in the groove and cannot come out easily. In order to prevent the stone-nipping in the circumferential groove, JP-A-2000-185525 and JP-A-2001-55013 propose provision of a plurality of narrow ridges or projections having a circumferential length of 5 to 100 mm, at regular intervals of 0.5 to 20 mm on the bottom surface of the circumferential grooves on the tire tread portion.
As a tire which achieves both water drainage property and noise resistance of the tire, JP-A-2-212203 discloses a tire having a rib pattern including a groove top having a step extending circumferentially of the tire substantially in parallel to the tread surface at a level of a predetermined depth from the tread surface and a groove bottom formed radially inwardly from the groove top, in which the groove bottom is serpentined circumferentially of the tire.
The linear main groove of the rib pattern generally formed into a V-shape in cross-section for preventing the stone-nipping, and hence the proximal portion of the rib is smaller in width in comparison with a ground contact surface. Therefore, when the rib comes into contact with the ground, the rib is deformed by vertical force on load and groove walls are bulged toward the center of the groove, the groove walls tend to bulge on the side of the ground contact surface having a smaller width in comparison with the groove bottom, and hence the uneven wear can easily occur due to the movement of rubber.
The tire attached to a steering wheel is subject to a relative slippage with respect to the road surface on the sides of the ground contact ends of the shoulders which are relatively smaller in diameter in relation to the curvature of the surface of the ground contact surface of the tire. Therefore, uneven wear tends to occur on the shoulder sides in comparison with the center side.
The rib pattern has the problem of the above-described stone-nipping, and also a problem in the braking property and the driving property on the wet road surface. Therefore, even when the short sipes are provided as described above, there remains a problem of lowering of the braking property on the wet road on and after the medium phase of wear.

Pneumatic tire with tread having circumferential main grooves