A high performance TMR element is fabricated by inserting an oxygen surfactant layer (OSL) between a pinned layer and AlOx tunnel barrier layer in a bottom spin valve configuration. The pinned layer preferably has a SyAP configuration with an outer pinned layer, a Ru coupling layer, and an inner pinned layer comprised of CoFeXBY/CoFeZ wherein x=0 to 70 atomic %, y=0 to 30 atomic %, and z=0 to 100 atomic %. The OSL is formed by treating the CoFeZ layer with oxygen plasma. The AlOx tunnel barrier has improved uniformity of about 2% across a 6 inch wafer and can be formed from an Al layer as thin as 5 Angstroms. As a result, the Hin value can be decreased by ⅓ to about 32 Oe. A dR/R of 25% and a RA of 3 ohm-cm2 have been achieved for TMR read head applications.

A TMR element is used in magnetic devices such as a Magnetic Random Access Memory (MRAM) structure and a magnetic read head. In FIG. 1, a TMR element 6 is shown wherein a stack of layers has a configuration in which two ferromagnetic layers are separated by a thin non-magnetic dielectric layer. In an MRAM structure, the TMR element is commonly referred to as a magnetic tunnel junction (MTJ) and is formed between a bottom electrode 5 or bottom conductor and a top electrode 14 also known as a top conductor. The bottom conductor 5 typically has a seed layer/Cu/capping layer configuration and is used to connect the TMR element 6 to an underlying transistor (not shown). In a magnetic read head, the TMR element 6 is formed between a bottom shield and a top shield (not shown). The bottom (seed) layer 7 in the TMR element 6 is generally comprised of one or more seed layers that promote a smooth and dense crystal growth in overlying layers. Above the seed layer 7 is an anti-ferromagnetic (AFM) pinning layer 8 and a first ferromagnetic layer that is a "pinned" layer 9 on the AFM layer. The thin tunnel barrier layer 10 above the pinned layer 9 is generally comprised of a dielectric material such as AlOx that may be formed by first depositing an Al layer and then performing an in-situ oxidation. The tunnel barrier layer 10 must be extremely uniform over the wafer since small AlOx thickness variations result in large variations in resistance. A more uniform tunnel barrier is required for advanced TMR designs which means the underlying layers should have improved thickness uniformity. A ferromagnetic "free" layer 11 is formed on the tunnel barrier layer 10 and is typically less than 50 Angstroms thick to obtain low switching fields in the patterned bits. At the top of the TMR element is a cap layer 12.
The MTJ stack in FIG. 1 has a so-called bottom spin valve configuration. Alternatively, an MTJ stack may have a top spin valve configuration in which a free layer is formed on a seed layer followed by sequentially forming a tunnel barrier layer, a pinned layer, AFM layer, and a cap layer.
The pinned layer 9 has a magnetic moment that is fixed in the y direction by exchange coupling with the adjacent AFM layer 8 that is also magnetized in the y direction. The free layer 11 has a magnetic moment that is either parallel or anti-parallel to the magnetic moment in the pinned layer. The tunnel barrier layer 10 is so thin that a current through it can be established by quantum mechanical tunneling of conduction electrons. The magnetic moment of the free layer may switch in response to external magnetic fields generated by passing a current through the bottom conductor 5 and top conductor 14. It is the relative orientation of the magnetic moments between the free and pinned layers that determines the tunneling current and therefore the resistance of the tunneling junction. When a sense current 15 is passed from the top conductor 14 to the bottom conductor 5 (or top shield to bottom shield in a read head) in a direction perpendicular to the TMR layers, a lower resistance is detected when the magnetization directions of the free and pinned layers are in a parallel state ("1" memory state) and a higher resistance is noted when they are in an anti-parallel state or "0" memory state.
Referring to FIG. 2, the TMR (MTJ) element 6 is shown interposed between the bottom conductor 5 and a top conductor 14 in a MRAM structure 20. The substrate 1 is comprised of a transistor (not shown) that is typically connected to the bottom conductor by a stud 4. A digit line 3 (word line in a 1T1MTJ) is formed below the MTJ element 6 and within a first insulation layer 2 that is usually a composite layer consisting of a stack of two or more dielectric layers which are not shown in order to simplify the drawing. The MTJ element 6 contacts the top conductor 14 (bit line) through the capping layer 12 and is formed in a second insulation layer 13 that is disposed on the bottom conductor 5. From a top-down perspective (not shown), a plurality of MTJ elements is formed in an array between multiple rows of bottom conductors (word lines) and multiple columns of top conductors (bit lines). Each MRAM cell has its own bottom conductor.
Switching of the free layer magnetization in the MTJ bit is accomplished by applying currents in orthogonal directions. For instance, the MTJ element may be elliptical in shape from a top-down view with a long axis running parallel to the underlying digit or word line 3. Currents i1 running transversely in the bit line 14 and bottom conductor 5 are orthogonal to the current i2 in the digit line (MTJ) or word line 3 (1T1MTJ). Thus, the current i1 provides the field parallel to the easy axis of the bit while the current i2 provides the perpendicular (hard axis) component of the field. The intersection of the conductive lines generates a peak field that is engineered to be just over the switching threshold of the MTJ.
In a read operation, the information stored in an MRAM cell is read by sensing the magnetic state (resistance level) of the MTJ element through a sense current flowing top to bottom through the cell in a current perpendicular to plane (CPP) configuration. During a write operation, information is written to the MRAM cell by changing the magnetic state in the free layer to an appropriate one by generating external magnetic fields as a result of applying bit line and word line currents in two crossing conductive lines, either above or below the MTJ element. In cross-point MRAM architecture, the top conductor or the bottom conductor participates in both read and write operations.
In addition to MRAM applications, a TMR element with a thinner tunnel barrier layer and a very low resistance×area (RA) value may be employed as a tunneling magnetoresistive (TMR) sensor between a bottom shield and top shield in a magnetic read head. A TMR sensor typically has a cross-sectional area of about 0.1 micron×0.1 micron at the air bearing surface (ABS) plane of the read head.
A high performance TMR element is characterized by a high TMR ratio which is dR/R where R is the minimum resistance of the TMR element and dR is the change in resistance observed by changing the magnetic state of the free layer. A higher dR/R improves the readout speed in an MRAM array. In order to achieve good tunnel barrier properties such as a specific junction resistance×area (RA) value and a high breakdown voltage (Vb), it is necessary to have a uniform tunnel barrier layer that is promoted by a smooth and flat underlying layers. For advanced TMR read head technology applications, a dR/R value above 20% and a RA value that is preferably below 10 ohm/μm2 are needed.
The performance of an MTJ element is enhanced according to U.S. Pat. No. 6,831,312 by incorporating an amorphous alloy such as CoFeB as the pinned layer and free layer in an MTJ stack. Boron is included in the alloy to control the recrystallization temperature and polarization of the resulting MTJ device.
In U.S. Pat. No. 6,479,096, a Pb surfactant layer is included in the deposition of a non-magnetic Cu spacer layer and promotes a face centered cubic Cu layer that is grown layer by layer to form a smooth surface. As a result, there is an improved interface between the Cu and adjacent layers that enhances sensor performance and reliability.
An oxide layer is formed as a magnetic domain control layer adjacent to a magneto-resistive sensor in U.S. Pat. No. 6,870,718. There may also be an oxide underlayer material between the magnetic domain control layer and sensor to prevent shunting from the magnetoresistive sensor to the magnetic domain control layer.
In U.S. Pat. No. 6,631,055, a flux guided MTJ is described wherein a pinned layer is comprised of an active and inactive region. The inactive region may be oxidized to reduce its electrical conductivity and lower the magnetic moment to near zero.
A CoFeB layer interposed between Cu layers in a CPP GMR spin valve is oxidized to provide an insulating barrier between the Cu layers in U.S. Patent Application 2003/0128481. The insulating barrier is a metal oxide with an undefined thickness.

TMR device with surfactant layer on top of CoFe


The present invention provides for a filter assembly (124) which includes a filter element (128) and a memory device (402). The memory device (402) allows for a record of the filter element's usage to be available at all times even if the filter assembly (124) is moved from one filtering system to another one. In another embodiment of the invention, the filter assembly (124) interacts with a filtering device such as air unit (130) which periodically updates the memory device (402) while the air unit (130) is operational. The air unit (130) also periodically checks to see if the filter assembly (124) has reached the end of its useful life. If so, the air unit provides an audible and/or visual alarm.

When working in environments laden with dust, fumes, air borne bacteria, mists, etc. it is common to wear a powered air-purifying respirator or other type of respiratory protection device. Powered air-purifying respirators protect wearers from such health threatening conditions as asbestos-countering dusts, radionuclides, blood borne pathogens, etc.
A typical powered-air respiratory system will include a head cover having a face shield and a belt-worn air filter unit which provides a flow of filtered air to the head cover via a breathing tube. The air filter unit will contain within its housing a filter such as a high efficiency particulate air (HEPA) filter or other type of filter for filtering out the impurities in the environment. During operation, ambient air is drawn through the belt-mounted air filter unit by a conventional blower motor/impeller assembly (hereinafter referred simply as the "blower motor assembly"). The unfiltered air is then drawn through the air unit's internal filter and the filtered air is then sent into the head cover.
In order to maintain the effectiveness of the respiratory system in filtering out impurities, it is critical that the disposable filter located in the air filter unit be replaced on a periodic basis. Failure to replace the filter on a timely basis causes the system to provide less than optimal filtering capability and can endanger the health of the respiratory system users.
Businesses such as those that have many personal respiratory systems for use by their employees will typically have a maintenance schedule which notifies them when each of the filters in each respiratory unit needs to be replaced. Although effective most of the time, this type of scheduled maintenance approach requires monitoring via a schedule which may or may not be followed on a timely basis. A bigger problem occurs if a filter from one respiratory system is exchanged with a filter from another system or with a previously used filter. In this particular situation, one may lose track of when to replace the particular filter since the filters are no longer associated with the same powered air unit. This situation may cause a filter to stay in service long after it has reached its end-of-life condition and has lost some or all of its filtering capabilities.
Although the above discussion has highlighted the problems associated with personal respiratory systems, the same problems can occur with any filtering device or system that uses a replaceable or portable filter. For example HVAC (heating/ventilation/air conditioning) systems, liquid filtering systems such as water purification systems for electronic assembly plants, automotive air and cabin filters, etc.
Given the portable nature of most filters used in personal respiratory systems and other types of fluid (e.g., air, gas and liquid) filtering devices/systems, a person who is changing a replaceable filter is usually never certain of how much life is left in the filter unless he installs a new filter straight from its original packaging. Otherwise, it could very well be that the filter that is being installed had been previously used elsewhere for some period of time. In these situations, it becomes very difficult to gauge a filter's end-of-life and determine when the filter should be changed. Using a filter beyond its useful life can cause all sorts of problems depending on the type of filtering system in question. For example, in the case of machinery, using a filter beyond its useful life can cause the machinery to prematurely fail. While in respiratory systems, a used-up filter can subject the user to serious health problems. A need thus exists in the art for a filter and system which can overcome the problems stated above.

Respiratory filter element having a storage device for keeping track of filter usage and a system for use therewith


A sparkline is associated with a location in a document to provide a visual representation of one or more data values included in the document. The sparkline is associated with a data source within the document including the one or more data values. The sparkline is generated by generating the visual representation based on the one or more data values with a matrix of points to be presented at the associated location in the document. The sparkline is presented at the associated location in the document. The sparkline is configured to be regenerated when one or more of the data values in the data source change.

Sparklines are small graphics embedded in a document, such as a text document or a spreadsheet, among the words, numbers, images or other content of the document. Sparklines can be used to graphically represent the content of one or more neighboring cells to provide a visual representation of the data. There are at least two advantages to using sparklines. First, as a "picture paints a thousand words," at a glance, a graph can quickly clearly show values, trends, and similar information. Second, by presenting such a graph in context within the document as opposed to presenting the graph on a separate page or screen, a viewer can more readily appreciate the information represented and/or compare the represented information with that represented by other sparklines.
In the case of creating sparkline graphs, conventionally, sparklines are created manually, often by simulating the generation of bars with a set of segment fonts that represent parts of bars, lines, or other graph features. Alternatively, a user could manually could select data and manually generate a chart, then try to scale the chart to fit the desired space.

Graphically displaying selected data sources within a grid


An information broadcasting system provides a large number of subscribers access to a large amount of information using one or more satellite transmission channels. The system can also use cable television transmission channels. A program supplier station stores an information database and tags all the information in the database with indices so as to form a single hierarchical structure which encompasses the entire information database. Portions of the information database are transmitted often, at least once per day, in order to provide the basic subscriber with information need to access the remainder of the database. The information provided by the basic subscriber service, which will typically include at least 50 gigabytes of data, is available to all subscribers without requiring two way communications between the subscribers and the program supplier station. Using a tiered system for scheduling transmission of the 50 gigabytes or so of information included in the basic subscriber service, as well as an intelligent subscriber request anticipation scheme for retrieving information before the subscriber asks for it, the present invention provides subscribers with reasonably quick access to all the contents of the large database while using only a modest amount of bandwidth. Furthermore, by reserving a portion of the system's bandwidth for satisfying requests for access to information not provided with the basic subscriber service, timely access to a virtually unlimited amount of information can be provided, using the same modest transmission bandwidth, to those subscribers willing to pay additional fees for that service.

The goal of computerized information servers is to provide a system that encourages use by subscribers, provides access to a large range of information, and which is flexible and inexpensive for information publishers. Computerized information services which exist today include Prodigy, Compuserve, and Dialog. Typically, the user either pays a monthly fee or a connect time fee for the most basic service and additional or special services are provided for additional fees.
All of the above mentioned computer services require two way communications between the user and the information server in order to service each new request by the user. In other words, the user sends requests, and then selected data is transmitted individually to that user in response to his/her request. This two way "query based" communication scheme is also prevalent in other types of information servers. For instance, the "pay per view" services provided by cable television companies allow a subscriber to call the company and request a movie.
The company then sends a signal to the subscriber's television signal decoder to enable it to decode the program on a particular channel during the period of time associated with the requested movie. In this case, the "information" (a program or movie) is being transmitted in any case, but subscribers are only provided access to the program if they pay a special fee.
Two major distinctions between the present invention and the prior art query based information servers are (1) the present invention has a bandwidth that is thousands of times of greater than the prior art systems, thereby enabling high speed, low cost distribution of information, and (2) the present invention greatly reduces the amount of two-way communication required between subscribers and the information server by automatically transmitting information that responds to most anticipated "requests" by subscribers. Only those subscriber requests not satisfied by the automatically transmitted information need to be conveyed to the information server.
The goal of the present invention is to provide widespread, high speed access to a virtual omniscient database having typically well in excess of a terabyte (10.sup.12 bytes) of data. Using a data channel capable of transmitting, say, 1.5 megabytes of data per second, the present invention can provide virtually instantaneous access to about a 100 megabytes of information, high speed access (e.g., within two hours) to about a gigabyte of information, and can provide medium speed access, with perhaps 12 or 24 hour turn-around, to perhaps 100 terabytes of information. Furthermore, such access can be provided to a very large set of users without having to use a large number of data channels.
The large bandwidth of the present invention's information server enables the system to provide subscribers with multimedia programming, including video and audio programming. This is unlike current query based information servers, whose low bandwidth makes the distribution of video and audio programming impractical. The ability of the present invention to distribute information in multimedia form makes it much more attractive to both subscribers and potential information publishers, including advertisers.
It is important to note that while a user has access to perhaps a terabtye, or even 100 terabytes or more, of data, the total amount of data that systems in accordance with the present invention system can transmit in any one day is much more limited, as will be described below. This is not unlike visiting the main library of a major university, such as Yale or Harvard University, having stacks containing several million volumes of books. Having "access" to all those books every single day does not means that a user can receive them all in one day, nor does it mean that all the users can receive all the books in a single day. Nevertheless, each particular book (file or program) is available on relatively short notice, and having access to such a large collection of books (data) is still very useful.
The present invention also has tremendous cost advantages compared with information distribution using compact disks (CDs), and is believed to have distribution costs on the order of one thousand times less than any competing distribution media. The present invention eliminates both the need to generate "master" disks and the need to manufacture any physical media. Since distribution is accomplished by broadcasting, the actual costs for "publishing" a million copies of an average length novel (i.e., distributing it to a million subscribers) would be on the order of just a few dollars, versus a cost on the order a dollar or more per copy for printing either CDs or traditional books, plus similar costs for the physical distribution, resulting in traditional distribution costs totalling millions of dollars. Furthermore, updates to previously distributed information are also distributed at equally low cost using the present invention, in contrast with CD based publishing which requires mailing or otherwise physically producing and distributing new CDs to all previous purchasers.

System for scheduling transmission of indexed and requested database tiers on demand at varying repetition rates


A non-acoustic measurement unit is provided to be integrated into an all-optical acoustic antenna, the non-acoustic measurement unit including a portion of an optical fiber, termed non-acoustic, intended to convey non-acoustic measurements, at least one non-acoustic sensor with electrical output able to deliver at least one electrical signal representative of at least one physical quantity, and a passive electro-optical transducer subjected to the electrical signal, the passive electro-optical transducer acting on a mechanical constraint undergone by a first sensitive zone of the optical fiber portion, in such a way that a value of a measurable property of a first optical signal conveyed by the non-acoustic optical fiber is representative of the electrical signal, and at least one photovoltaic cell coupled electrically to the non-acoustic sensor so as to electrically supply the sensor.

A passive sonar furthermore comprises a supply unit, making it possible to produce energy intended to supply the sensors and a processing unit intended to process the measurements arising from the various sensors so as to detect and then optionally identify and locate objects. The supply unit and the processing unit are sited remotely aboard the marine vessel or on a land station. Provision is made for a link between the acoustic antenna and the supply unit as well as the processing unit. When this link is a link comprising solely one or more optical fibers, one speaks of an all-optical acoustic antenna. Stated otherwise, the links used for the transmission of the supply energy from the supply unit to the antenna and for the transmission, to the processing unit, of the information arising from the sensors are optical fibers. These solutions are of small bulk, are cheap and lightweight. They are insensitive to electromagnetic disturbances. They make it possible, on account of the weak energy attenuation in the optical fibers, to read the measurements performed by the sensors at several kilometers, and to do so without any electrical energy source being connected to the sensors.
All-optical acoustic antennas comprise a plurality of fiber optic hydrophones acting on respective sensitive zones of one or more optical fibers. By fiber optic hydrophone is meant a hydrophone comprising an optical fiber which delivers a measurement signal which is an optical signal. This optical signal is conveyed by an optical fiber. A measurable physical property of this optical signal is representative of the acoustic pressure to which the hydrophone is subjected.
Hydrophones are acoustic sensors intended to measure an acoustic pressure also called dynamic pressure, that is to say fast variations of low pressure. The acoustic pressure measured by a hydrophone is typically between 30 and 200 dB reference 1 μPa and varies at frequencies lying between 1 Hz and 100 kHz.
When acoustic sensors are submerged in water they are also subjected to hydrostatic pressure also called static pressure which increases by approximately 10 000 Pa per meter of water. Hydrophones being used at depth, the hydrostatic pressure undergone by a hydrophone is typically greater than 10 000 Pa. In order to make it possible to measure the acoustic pressure, hydrophones filter the hydrostatic pressure, for example by means of an integrated mechanical or bolt-on high-pass filter of the electrical type. Stated otherwise, in order to avoid saturation phenomena and allow the measurement of the acoustic pressure, acoustic sensors do not make it possible to measure the hydrostatic pressure, that is to say a pressure at least equal to 10 000 Pa, otherwise they would not make it possible to measure the acoustic pressure, the difference in amplitude between the acoustic pressure and the static pressure being of the order of 100 000 000 to 1 000 000 000 Pa.
The aim of passive sonars is to detect and to locate objects in the water. This aim is achieved by means of the acoustic reception antenna but the location of objects makes it necessary to integrate into the acoustic antenna, one or more additional non-acoustic sensors such as, for example, at least one heading sensor, at least one accelerometer, at least one temperature sensor and/or at least one static (or immersion) pressure sensor. The measurements arising from these sensors are used for the detection and/or the location of objects in the water. By non-acoustic sensor is meant a sensor configured to measure one or more physical quantities, each measured physical quantity being a measurement other than an acoustic pressure.
Some of these sensors exist in the form of optical fiber sensors. Such sensors deliver an optical signal representative of the quantity to be measured, said optical signal being conveyed by an optical fiber. There exist for example optical fiber temperature sensors and optical fiber static-pressure sensors. Their integration into the streamer is then easy. However, certain non-acoustic sensors, such as for example heading sensors, exist only in the form of sensors with electrical output. By sensor with electrical output is meant a sensor whose sensitive element delivers an electrical signal, such as for example a voltage or an intensity, representative of a measured physical quantity. The integration of this type of sensor into an all-optical measurement system and in particular its integration into an acoustic antenna of streamer type is then complex.


A precursor base for use in a bakery dough product comprising an acidic concentrate, at least one type of sugar, yeast, at least one type of flour, non-fat dry milk and at least one type of lactic acid producing bacteria and a process for producing the precursor base are disclosed. The precursor base is useful in a process for producing a precursor slurry (or active ferment concentrate) for use in making a preferment dough mixture for the preparation of the bakery dough product. In addition, processes for preparing the precursor slurry and the preferment dough mixture and an apparatus for producing the preferment dough mixture are disclosed.

This invention is directed to a new fermentation system that drastically reduces the fermentation time and equipment size necessary to produce bakery products without corresponding reductions in the quality of the bakery products.
The bakery industry has been faced with the problems of rapidly increasing manufacturing costs associated with the steadily rising costs of labor, energy, raw materials, real estate and other such factors. To combat these increasing costs, the bakery industry began to look for increased productivity. The bakery industry, in its yeast-raised product segment, found that a logical place to decrease manufacturing costs was in the most time-consuming element, namely the required fermentation time of the bakery product. Various methods were developed to speed-up fermentation by means of various chemical and physical inducements. In the early stages of such developments, the industry found no apparent problems associated with the reduction of fermentation time. However, as the trend to cut required fermentation time continued, the industry has continued to face increasing new problems, including adverse and undesirable effects on the quality of the bakery products. Bread, rolls, buns and other bakery products started having decreasing amounts of flavor and aroma along with the gradual loss of other such desirable characteristics as texture, aesthetic appeal and good shelf life.
One widely accepted method to produce high-quality products is the "sponge and dough", or batch process method which results in the high-quality products with good flavor, aroma, desirable texture, and good shelf life. However, the sponge and dough method is also the most costly method due to the requirements of double mixing, approximately four hours fermentation time, and extra handling, all of which require much labor, space, energy, and time. The sponge and dough method is also intolerant of disruptions in the production process of even short durations thus resulting in higher waste if the process is interrupted.
Other methods of production include the flour preferment method, which normally contains up to about 50% of the total flour and which produces good quality products. However, there is some sacrifice of desirable end-product characteristics when compared to the sponge and dough method. The flour preferment method, due to the high flour content, requires heavy-duty equipment, large pumps to handle the viscosity of the high flour content preferment product, and high energy consumption for cooling. In addition, frequent maintenance problems occur in the heat exchange and process flow equipment used in the flour preferment method.
Another production method, the water preferment method, contains no flour, yet offers good yeast distribution. However, the water preferment method requires considerable amounts of water and sugar and produces below average quality bakery goods. In addition, such method is very sensitive at the yeast saturation point and therefore requires intensive monitoring during the preferment process in order to maintain bakery product consistency.
Still another method, the no-time dough method is very simple and requires no preferment. However, the no-time dough method produces lower quality goods that sacrifice flavor, aroma and shelf life keeping qualities in exchange for the lower production costs associated with the no-time dough method.
Finally, the continuous mixing method is convenient and cost efficient for the baking industry. However, the continuous mixing method produces the least desirable quality bakery products in terms of flavor, aroma texture and keeping qualities.
Previously, it was believed that the function of fermentation was merely related to the gas production in the dough, which would cause the dough to rise and expand. However, extensive investigation into the function of fermentation has established that several relevant processes occur during fermentation. Along with the gas production, there is the production of chemically identifiable substances such as organic acids, ketones and aldehydes which are end-products of the fermentation process itself. The bakery industry has learned that the only function effectively speeded up in a hastened fermentation is the gas production. The other relevant processes and substances have little or no time to be produced during a fast fermentation system. As such, those processes and substances are either missing or undesirably low in such doughs. These substances have been found to give flavor and aroma to the product and also cause the various chemical and physical interactions required for a good yeast raised system. Therefore, any compromise in the fermentation system will result, in various degrees, in a sacrifice of flavor, aroma, texture and other desirable characteristics. The bakery industry and the flavor companies and other food ingredient companies began developing compensating materials to replace the sacrificed characteristics, some through flavor chemistry, others through enzyme related materials. A few of these compensating materials have helped to partially overcome the blandness of these fast fermentation bakery products, but none of the compensating materials has really created or replaced the genuine flavor and other qualities that result from a good fermentation system. Therefore, the current remedies or compensating materials have not offered much improvement and the baking industry is still addressing the quality deterioration problem associated with shorter fermentation systems and the resultant dropping per capita consumption of bakery products.


A securing apparatus including cap adapted for slidably receiving a top end of a stake. Also included is an alignment member adapted for receiving a top edge of a form board and for slidably receiving the stake such that stake is rigidly held substantially parallel to the form board. The alignment member possesses a sleeve as well as L-shaped holding portion adapted to fit over the top edge of a form board. The alignment member possesses a sleeve as well as L-shaped holding portion adapted to fit over the top edge of a form board.

1. Field of the Invention
The present invention relates to foundation form braces and more particularly pertains to a new stake protector for protecting stakes used in concrete form construction from being damaged.
2. Description of the Prior Art
The use of foundation form braces is known in the prior art. More specifically, foundation form braces heretofore devised and utilized are known to consist basically of familiar, expected and obvious structural configurations, notwithstanding the myriad of designs encompassed by the crowded prior art which have been developed for the fulfillment of countless objectives and requirements.
Known prior art includes U.S. Pat. Nos. 5,076,535; 5,616,272; 1,329,177; 4,411,404; 1,727,250; and U.S. Pat. No. Des. 317,250.
In these respects, the stake protector according to the present invention substantially departs from the conventional concepts and designs of the prior art, and in so doing provides an apparatus primarily developed for the purpose of protecting stakes used in concrete form construction from being damaged.


A truing lathe has its components mounted on a base. A pair of stands for holding the workpiece are mounted on the base. The stands have a pair of notches where the workpiece rests and is rotatable therein. An electric motor with a pulley head is mounted on one of the stands and below the notches so that the motor drive shaft aligns with the axis of rotation of the workpiece. One loop of a stretchable endless belt is slipped over the midsection of the workpiece while the other loop is stretched to fit around the drive pulley. The cutting bit is mounted on separate longitudinally and transversely moveable blocks so that the bit can be adjusted radially and longitudinally relative to the axis of rotation of the workpiece to machine the workpiece. The mounting stand and the way the workpiece is rotated results in minimal precession of the workpiece on the lathe to allow for a closer and truer machining of the workpiece. The lathe is compactly built and can be powered by batteries under field conditions to repair electric motors used in radio controlled model cars. The type of electric motor used to run the lathe is the same type of electric motor used to power radio controlled model cars. The lathe also can be used in the hobbyist's shop.

1. Field of the Invention
TURNING: Portable lathe; lathe with a tool and work rest; the work rest having a center rest. TURNING: Work driver.
2. Description of the Prior Art
U.S. Pat. No. 3,128,533 issued in 1962 to E. Haugland discloses a portable motor driven device for turning down and undercutting the commutators of motors and generators having shafts of different lengths and diameters. The drive means for turning the commutator is provided by an electric motor having an attached pulley. A pair of opposed bearings and brackets hold the ends of the commutator in position. An endless belt has one end looped and connected to the pulley on the drive motor while the other looped end surrounds and frictionally engages the armature. The rotating drive motor, pulley and endless belt cause the commutator to rotate so that one can true the commutator with an adjustable tool bit.
Radio controlled model cars have become a popular hobby, just as radio controlled model airplanes have been a popular hobby for decades. Radio controlled model cars and model airplanes are similar in that each has a self-contained motor and power source, each has a wireless receiving device in the unit, and each is controlled by a wireless transmitter that is operated by the hobbyist. Both hobbies are conducted out in the field or at large vacant parking lots. Field conditions require the hobbyist to take along with him or her a tool kit and spare parts because of frequent mechanical breakdown of the car or airplane.
The typical radio controlled car has four wheels attached to a frame. The frame holds the wireless receiver, control cables, a battery pack and the electric drive motor. The two rear wheels are the drive wheels, which are mounted on the frame and are interconnected by a drive shaft. The electric motor is mounted parallel to the drive shaft so that the rotating motor shaft rotates parallel to and in unison with the drive shaft. An endless belt interconnects a pulley on the drive shaft with a pulley on the electric motor shaft to transfer the power from the motor to the drive wheels. The typical electric motor used in radio controlled model cars runs on direct current usually at 7.2 volts or 8.4 volts. The motor has a compact cylindrical housing about two inches long and one and one-half inches in diameter. A cylindrical armature around a power shaft is rotatably positioned in the housing. A commutator is also secured adjacent to the armature. The commutator is cylindrical in shape, and it has a pair of brushes touching it through which electricity flows. The rotation of the electric motor is adjustable and is controlled by a speed control device mounted in the car. The speed control device is in turn controlled by the operator of the transmitter. The speed control device can adjust the amount of current flowing to the motor from the onboard batteries. The batteries used are nickel-cadmium rechargeable batteries so that the batteries can be recharged after each use. Each battery, which is called a cell, is usually 1.25 volts and is packed 6, 7, or 8 to a power pack for interchangeable replacement on the model car. The electric motor is capable of reaching 50,000 rpms at full power. The electric motor has very close tolerances. During model car races, the electric motor is operated at full power for extensive periods of time. The electric motor requires frequent cleaning and truing of its commutator, because of pitting, arcing, and normal wear and tear, to keep the motor operating at its full capability. Conditions encountered out in the field occasionally require the electric motor be removed from the car, disassembled, the commutator turned, and the motor reinstalled in the car.


A storage tray provides storage for multiple types of wires, catheters, and other instruments used during surgical procedures. The storage tray includes a base and a set of walls forming a basin that holds liquid. A wire containment section within the basin holds multiple coiled guidewires in a wire channel filled with the liquid. The wire containment section includes an inner wall and one or more wall segments forming an outer boundary of the wire channel. Flaps extend orthogonally from the walls and over portions of the wire channel to prevent the guidewire from springing out of the wire channel. A wire holder outside the wire channel holds end portions of the guidewires. Pulling an end portion of one of the coiled guidewires horizontally causes the guidewire to slide along the inner wall for separation and removal from the storage tray.

Endovascular procedures have become the preferred method of intervention for patients with vascular and cardiovascular disease. These procedures allow lower complications rates and quicker recovery times because instead of making a large incision, only a small puncture, typically through the groin, is required for access. Guidewires, catheters, and interventional devices such as balloons and stents are then threaded through this puncture and guided through different blood vessels to access and treat the patient.
Guidewires are used to direct a catheter to an identified site within a cardiovascular or peripheral vascular system of a patient for the purpose of diagnosis and/or treatment. Catheters are used for administration of fluid, such a saline, contrast, or therapeutic agents, at the identified site. The guidewire is typically placed into a blood vessel of the patient and is directed by a medical practitioner to the identified site of the patient's body. A catheter is then advanced over the guidewire until the functional structure of the catheter is located in proximity of the identified site.
Different sizes/gages of guidewires and different sizes of catheters may be used during a surgical procedure for different applications. Thus, multiple guidewires, catheters and other devices are typically laid out for access during a surgical procedure. Management of guidewires, catheters, and interventional devices during surgical procedures can become an unwanted distraction. Used guidewires or catheters have conventionally been coiled up manually and held down on an operating table with wet towels, held in a water basin, simply placed on the operating table, or sometimes fall to the floor after being used.

Tray for temporary storage of catheters and other coiled surgical devices


A dispenser in which a dry powder (one component of a two-part adhesive tissue sealant and/or adhesive) is stored in a container (e.g., a carpule) having a septum at one end, an open end opposite the septum, and a movable plug. The powder is retained at the septum end of the container by the movable plug, which is displaced and pushed back as the solvent used for reconstituting the powder is introduced (e.g., through the septum). The second part of the tissue sealant is contained within a second container, also with a movable plug. After the first part is reconstituted, a manifold is fitted which pierces both septums and allows the contents to be dispensed. A dual syringe body supports the containers, and has pistons that enter the open ends to advance the movable plugs. Other embodiments of tissue adhesive and/or sealant dispensers and kits as well as methods of preparing tissue sealants are also described.

The invention relates generally to the dispensing of adhesive tissue sealants and other liquid preparations, including those requiring mixing immediately prior to use.
A variety of techniques have been used to bond or seal living tissue. For example, different types of tissues have been mechanically bound or sealed with a number of procedures, materials and methods including sutures, staples, tapes and bandages. In some applications, these materials are made of absorbable materials that are intended to bond and/or seal tissue as it heals and then to be absorbed over a period of time.
A recent addition to the techniques that can be used is application of an absorbable adhesive sealant composition to bond and/or seal tissue. The adhesive composition is readily formed from a two component mixture that includes a first part of a cross-linking agent and a second part of a protein, preferably a serum protein such as albumin. When the two parts of the mixture are combined, the mixture is initially liquid. The combined mixture then cures in vivo on the surface of tissue to give a substantive composition that securely bonds to the tissue. Additional details can be found in commonly owned U.S. Pat. No. 5,583,114, xe2x80x9cADHESIVE SEALANT COMPOSITION,xe2x80x9d to Barrows et al, the entire contents of which are hereby incorporated by reference.
Among the limitations on the widespread use of this material are that the first part, when rehydrated, has a limited shelf life and must be dissolved relatively shortly before use. Another limitation is that the two parts must be kept strictly separate until dispensed onto the tissue because the reaction time of the forming of the finished sealant is quite fast. These limitations increase the complexity for appropriate dispensing by the medical practitioner to form an effective adhesive tissue sealant on the tissue surface.
A known approach for dispensing two-part tissue sealants is to supply the user with a kit consisting of at least two syringes, vials containing the components in dry powder form, a syringe body for receiving and supporting both syringes, and a housing for connecting the two syringes to a common nozzle. The user fills the syringes by piercing the septums on the vials and withdrawing solution into the barrel of the syringe. If a component is in powder form within a vial, the user first injects a solvent and then withdraws the reconstituted solution. The needles on the syringes are removed, the syringe barrels and plungers are supported in housing, and the syringe nozzles are received in the housing.
Another approach is disclosed in U.S. Pat. No. 4,735,616 to Eibl. Dry powder is stored within both barrels of a dual barrel syringe. In each instance, the powder is stored on one side of a sliding plug, and solvent is stored on the other side. When the user presses down on the syringe plunger, the plugs slide along the barrels to positions at which the barrels each have a bulge that provides a bypass for the solvent to reach the powder.
In these prior art dispensers, the manifold passages connecting the two syringes to the common nozzle are typically narrow conduits of circular cross section. E.g., U.S. Pat. No. 4,631,055 to Redl.
Carpules have been used in some syringes; e.g., U.S. Pat. No. 3,767,085 to Cannon shows a dual carpule syringe for mixing compositions used in dentistry.
A kit for reconstitution and application of Tisseel(copyright) fibrin sealant including VH Sealer Protein and Thrombin solutions is currently available from Baxter Healthcare Corporation""s division of Glendale, Calif. The use of this product requires a complicated procedure. As a result, it is difficult to prepare the fibrin sealant with this kit and it is also difficult to use the applicator. Additionally, the applicator is said to suffer from clogging problems.
The Tisseel(copyright) kit comprises a first bottle containing freeze-dried thrombin, a second bottle with calcium chloride solution designed to reconstitute the thrombin; a third bottle with sealer protein concentrate, and a fourth bottle with fibrinolysis inhibitor solution. A Fibrinotherm(copyright) Heating and Stirring Device is used to heat and stir the components such as the sealer protein concentrate and the fibrinolysis inhibitor solution. Alternatively, a hot water bath or incubator may be used. This requires components to be heated above room temperature prior to use, further complicating the procedure.
The packaging of this device also causes problems. Two syringes and at least two (and preferably four) exposed needles are required simply to reconstitute the thrombin and sealer protein concentrate. For transfer of the Tisseel(copyright) VH solution and the Thrombin Solution to the sterile field in the operating room, the scrub nurse should withdraw the solutions while the circulating nurse holds the unsterile vials. This requires the coordination of two healthcare workers, one of which directs a sharp instrument (needle) toward the other. This is required twice to prepare the applicator of the product.
The packaging also includes multiple pouches that contribute to the waste and clutter at the location of medical care.
Outside the United States, a kit is available for use in preparing and dispensing the Beriplast(copyright) fibrin adhesive. This kit includes four vials with fibrinogen concentrate in a first vial, aprotinin solution in a second vial, thrombin in a third vial and calcium chloride solution in a fourth vial. An adapter with dual piercers is available in some kits which helps place the contents of one vial into another. However, once the two components of the fibrin adhesive are in solution form, the kit nevertheless requires two exposed needles to transfer the solutions from the mixed vials into the separate syringes of the delivery device. Since the external portion of the vials are considered non-sterile (i.e. all four vials are packaged in a box), it is believed that this kit also requires the coordination of two healthcare workers (one associated with the sterile field, one outside), one of which directs a sharp instrument (needle) toward the other.
The present invention provides an improved dispenser suitable for quickly and easily setting up and dispensing multi-part tissue sealants or other multi-part compositions requiring separation of the components until just prior to application on the tissue surface.
In a first aspect, the invention features a dispenser having a container (e.g., a carpule) with at least a portion of a first component of a multi-part tissue sealant and/or adhesive (e.g. a dry powder) having a septum at one end, an open end opposite the septum, and a movable plug. The powder may be retained at the septum end of the container by the movable plug, which is preferably displaced and pushed back as a solvent used for reconstituting the powder is introduced (e.g., through the septum). At least a portion (and preferably all) of a second component of the tissue sealant (e.g. a liquid) is contained within a second container, also with a movable plug. After the first component is reconstituted, a housing (preferably a manifold) having piercers is used to pierce both septums and allow the contents to be dispensed. Preferably, the piercers are placed in a protected position so as not to expose a user to contact with the piercers. A body supports the containers. Pistons are provided to advance the movable plugs.
Preferred implementations of the first aspect may include one or more of the following features.
The first component may be a dry powder of a water-compatible or water-soluble cross-linking agent.
The aqueous solution for dissolving the powder may be introduced through the first septum (e.g., either via the piercer or via an injection through the septum by a syringe).
The movable plug may be positioned in a position in which the space between the plug and the septum is substantially the minimum necessary to contain the dry powder, thereby reducing the amount of air in that space and consequently the amount of pressure rise associated with injecting liquid through the septum. The movable plug can move away from the septum as liquid is injected to reduce any pressure rise.
The second component stored in the second carpule may be a solution.
The second component may be a protein dissolved in an aqueous buffer and capable of reacting with the solution of the first component to provide the adhesive tissue sealant.
The body may comprise a retainer for protecting and/or holding the containers.
In a second aspect, the invention features an improved manifold for a two-part dispenser. Two containers (e.g., carpules), each having a septum at one end, an open end opposite the septum, and a movable plug, are supported in a dual syringe body, which has pistons configured to enter the open ends of the containers to advance the movable plugs. A manifold has cavities that receive the septum ends of the containers, and a disk supporting a piercer (e.g., hollow needle) is mounted in the base of each cavity so that the septum of a container is pierced when it is installed in a cavity. Each disk is supported a distance above the base of a cavity to form a plenum defined by the disk and adjacent walls of the base of the cavity. Liquid exiting a container travels through the lumen of the piercer, then into the adjacent plenum, and then out of the plenum along a conduit extending to the nozzle. This arrangement of disks each supporting a piercer and forming a plenum provides an effective, relatively low-cost way of constructing a manifold for connecting carpule piercers to a common nozzle.
Preferred implementations of the second aspect may include one or more of the following features.
Each disk may be sealed to the surrounding wall of the cavity (e.g., by an elastomeric sealing member on the disk) so that the adjacent plenum is defined by the disk and the base of the cavity.
The conduit and piercer lumen may each communicate with the plenum at laterally spaced apart locations so that flow from the piercer lumen to the conduit changes direction from a generally longitudinal flow path through the piercer lumen, to a generally lateral direction in the plenum, and then to a generally longitudinal flow path in the conduit.
The disk may be supported from the base of the cavity by standoffs.
The first container may contain a quantity of the first component in the form of a dry powder so that the first component must be dissolved prior to use by introduction of an aqueous solvent.
The second container may contain a quantity of protein in an aqueous buffer that is capable of reacting with a dissolved first component to provide an adhesive tissue sealant.
In a third aspect, the invention features a method for dispensing a component stored in a dispenser in dry powder form and reconstituted by introduction of a solvent. A carpule is provided with a septum at one end, an open end opposite the septum end, and a movable plug disposed therebetween. The dry powder is stored between the septum and the movable plug. Solvent is introduced into the interior of the container by piercing the septum with a syringe and injecting the solvent into the carpule. The carpule is installed in a syringe body and manifold, the latter providing a flow path from the piercer to an outlet nozzle.
Preferred implementations of the third aspect may include one or more of the following features.
Installing the carpule in the syringe body and manifold may occur before or after the solvent is injected through the septum.
The first movable plug may be positioned in a position in which the space between the plug and the septum is substantially the minimum necessary to contain the dry powder, thereby reducing the amount of air in that space and reducing the pressure increase within the carpule when the solvent is introduced by piercing the first septum. The movable plug can move away from the septum as liquid is injected to reduce any pressure rise.
The dispenser may comprise a second carpule comprising a second septum at one end, an open end opposite the second septum, and a second movable plug disposed therein, the second carpule containing a second component, and the syringe body and manifold may be sized and configured to accept the first and second carpule.
The second component may be a protein in an aqueous buffer and capable of reacting with the first component to provide an adhesive tissue sealant.
The dry powder of the first component may be a water-compatible or water-soluble cross-linking agent capable of reacting with the second component to provide the adhesive tissue sealant.
In another aspect, the present invention comprises a kit having components useful for preparing and delivering a tissue sealant and/or adhesive having first and second components. The kit comprises a first container having a septum, at least a portion of the first component stored therein, and outer portions. The kit includes a second container having at least a portion of the second component therein, a septum, and outer portions. At least one vial with a solvent for at least one of the first and second components is also present in the kit. The kit further includes a syringe and needle; and a sterile housing having first and second piercers located in protected positions and a portion that is sized and shaped to receive the first and second containers.
In another aspect, the present invention comprises a method of preparing a multiple component tissue sealant and/or adhesive just prior to use comprising the steps of providing a first container having a septum and a dry powder stored therein; providing a second container having a septum and a liquid therein; providing a vial with a solvent for the dry powder therein; providing a syringe and needle; providing a housing having first and second piercers located in protected positions and a portion that is sized and shaped to receive the first and second containers; withdrawing the solvent from the vial with the syringe and needle; placing the solvent in the first container; and installing the first and second containers in the housing and piercing the septums of the first and second containers with the first and second piercers without exposing a user to physical contant with the piercers.
The invention provides a significantly simpler and easier to use dispenser, one particularly well suited to handling adhesive tissue sealants. It is also simple and relatively inexpensive to manufacture. It delivers excellent performance, and is particularly good at mixing solutions reconstituted from dry powder.
Other features and advantages of the invention will be apparent from the following description and drawings, and from the claims.

Dispenser for an adhesive tissue sealant


Rifle with interchangeable barrel having an interchangeable barrel formed by attachment of a barrel to a receiving block which has locking lugs and is provided with alignment structure for aligning the interchangeable barrel with other components of the rifle and having a threaded passageway to receive a screw such that the interchangeable barrel may be easily removed and replaced.

In the past there have been a number of attempts to produce various types of firearms with interchangeable barrels. Most of this effort has been concentrated on shotguns designed to accommodate different barrels. Some of these attempts are shown in U.S. Pat. Nos. 4,989,359 and 2,529,733. However, with shotguns, being area-fire weapons, there was not great concern about small variations in fit of the barrel which effect accuracy. Also, there have been attempts to place interchangeable barrels on pistols, together with interchangeable cylinders, as shown in U.S. Pat. No. 4,297,801.
An attempt to provide a rifle with interchangeable barrels is shown in U.S. Pat. No. 3,611,611, which requires the use of a concentric sleeve over the barrel to provide a rifle with an interchangeable barrel. This system suffers the disadvantages that it is complex and there is the possibility for slack between the rifle barrel and the sleeve, which can affect accuracy each time a barrel is removed and replaced.
There has been a continuing need to provide a rifle with interchangeable barrels which are both easily and quickly changed while maintaining accuracy of the weapon. The present invention provides a rifle with interchangeable barrels which conserves cost, allows the shooter to use one stock with which he is familiar and comfortable, and provides comparable weight and balance to the total firearm even when the different barrels are attached. All these factors are believed to be helpful to maintaining accuracy by allowing the shooter to maintain the same feel and touch, even though different caliber barrels are utilized. A major shortcoming of prior attempts to provide an interchangeable barrel for a rifle has been to achieve alignment of the barrel and sight system to maintain accuracy. Thus, interchangeable barrels have been successful in shotguns because minor variations in accuracy do not have much effect with these area-fire weapons. Interchangeable barrels or barrel inserts have found some use with pistols, but again in uses where accuracy is not a paramount concern. There has not been a successful large bore hunting rifle which uses interchangeable barrels. It is believed that this is directly attributable to difficulties with zeroing the weapon each time the barrel is changed. The present invention now permits use of interchangeable barrels for rifles which do not require rezeroing the weapon each time the barrel is changed.
Thus, the present invention satisfies a long-felt need and offers substantial advantages to the shooter. These advantages include being able to use the same stock assembly trigger housing and bolt guide configuration for the different barrels. Thus, the shooter continues to utilize the basic components with which he is familiar and comfortable. When the weapon is shouldered, it will come to his accustomed shooting position, unlike using separate rifles of the desired caliber where variations in stock length, shape and thickness require an adjustment for each different rifle. Also, the shooter has the advantage of being familiar with the same trigger pull and bolt action, thus further enhancing consistent habits which improve marksmanship. The rifle of the present invention also has the advantage that for a single stock assembly, a number of different rifle calibers may be used, thus allowing a hunter to take one stock and several barrels in a convenient-sized case for air travel to hunt large game and small game on one trip without the need to carry two or three different complete firearms in bulky containers such as long rifle cases which are frequently over four feet in length. The rifle of the present invention also offers the advantage that the system and mechanism for achieving the interchangeability of the barrels, each with its own sight system, allows the consistent return to zero each time the barrel is removed and replaced. Thus, the shooter only needs to zero the barrel initially. After that, the mounting mechanism allows the barrel to be removed and replaced without the need to rezero the rifle when barrels are changed. Thus, for example, when the hunter is on a trip in the wilderness, he may change barrels without the need to rezero the barrel. Without this feature, interchangeable barrels are not practical for the hunter, as many times he does not have the facilities, targets and other equipment necessary to accurately rezero the barrel while in the field.


A predominatly hardware-based system for rapidly generating overlay images by painting techniques using a host computer with appropriate graphics-generation operator interface, and for manipulating overlay images with respect to a background image. The system provides for rapid, convenient control of such imaging aspects as color alteration, repositioning the overlays on the background, and predetermining the amount of mask protection to be associated with each image pixel. The system can be readily realized, using available integrated crcuits, in the form of a host-computer plug-in accessory. A bidirectional multiple bus structure serves to interconnect the circuit boards, permitting convenient host-software-controlled configuration of the system.

The present invention relates generally to the processing of electronic images for video display, more particularly to the processing of computer-generated video images, and especially to the manipulation of complex video images involving the presentation of overlay images over a background image.
The use of computers to generate video images has become widespread and has brought with it the need to efficiently generate and manipulate such images. When such images involve the use of the technique of overlay, in which a background image is displayed with one or more secondary images overlaying various parts of the background image, the operator needs to be provided with several convenient and efficient controls so that the final display image can be produced in the minimum time.
The colors used in displaying the overlay images must be readily changeable as needed to enhance the appearance of the overlay images with respect to the background image. The position of the overlay images must also be easily altered by the operator. Further, it must be possible to provide some degree of protection to the various image portions such that an overlay image can be prevented from obscuring significant details of the image(s) lying beneath it.
Computer systems for handling these matters have in the past relied to a significant extent on construction of a complex display image including overlays by the use of a single image plane representing the complex display image in memory. In order to alter the various portions of the image to insert overlays, the host computer utilized software to serially read each of the data points in the region of the memory plane where changes were to be made, and then wrote new data in this region to represent the altered image.
Such software-intensive techniques were slow and cumbersome, and provided no backup capability, since the original data values in the image memory plane were lost as soon as new data was written into the affected addresses.

Video overlay image processing apparatus


A Z-axis magnetic field gradient coil structure for producing a desired magnetic field gradient without increasing the electrical resistance of conductors forming a coil pattern. The coil structure comprises a flexible insulative substrate to be wound on a cylindrical bobbin. The substrate is several times as long as the circumference of the bobbin. The coil pattern is formed on the substrate by etching techniques and comprises pairs of conductive strips and conductive interconnectors for interconnecting these strips. The pairs of conductive strips are symmetrical with respect to the central line of the pattern.

In an MR system, it is necessary that a magnetic field gradient be produced along each of the three mutually orthogonal axes (X-, Y-, and Z-axes) of a Cartesian coordinate system. Coils for producing a Z-axis magnetic field gradient in a system where a static magnetic field is generated in the Z-axis direction have been heretofore fabricated by winding wires on a bobbin.
In this prior art technique, annular grooves are formed in given positions on a bobbin, and wires are wound a given number of times in the grooves in order to produce a desired magnetic field gradient. This method needs skillfulness to fabricate the coils. Also, it is difficult to machine this coil assembly.
A method of fabricating Z-axis gradient coils by forming a desired coil pattern on a flexible insulative substrate, winding the substrate around a bobbin, and bonding the substrate to the bobbin has been proposed as disclosed in U.S. Pat. No. 4,910,462 entitled "Etched Z-Axis Gradient Coils For NMR System". These coils need neither the prior art bobbin-machining step nor the prior art wire-winding step. Also, it is easy to fabricate these Z-axis gradient coils, because it is only necessary that the flexible insulative substrate be wound on and bonded to the bobbin.
Where a strong magnetic field gradient is produced using the Z-axis gradient coils disclosed in the above-cited U.S. Pat. No. 4,910,462, it is necessary to increase the number of conductive strips existing in unit length of coil by reducing the width of each conductive strip contained in the coil pattern. Where the conductive strips are narrowed in this way, the electrical resistance of each conductive strip and hence the electrical resistance of the whole coil is increased. Generally, to cause an electrical current to flow through a coil of large electrical resistance, a power supply of a large capacity is necessary. Furthermore, heat generated by the coil presents problems. Therefore, coils having smaller electrical resistance are preferred.

Z-axis magnetic field gradient coil structure for magnetic resonance system


In order to reduce memory requirements in a chip for demodulating digital video broadcast signals, symbol data values stored for a channel equalisation process have their scattered pilots removed, to achieve a 9% reduction in memory space required. This is achieved by providing a write pointer and a read pointer, the write pointer being arranged to exclude carriers carrying scattered pilots, and the read pointer being arranged to read the stored symbol data, but to add nominal data values at positions of excluded scattered pilots.

This invention relates to method and apparatus for storage of signal samples, particularly though not exclusively in the demodulation of digital video broadcast (DVB) signals.
There are currently two major types of DVB, namely, terrestrial broadcasting and satellite/cable broadcasting. The invention is particularly, though not exclusively concerned with terrestrial broadcasting, which has special problems, particularly in communication channel impairment, arising from adjacent television channels, multipath, and co-channel interference, for example. A type of transmission which has been developed to meet these problems is known as Coded Orthogonal Frequency Division Multiplexing (COFDM)xe2x80x94see for example xe2x80x9cExplaining Some of the Magic of COFDMxe2x80x9d Stott, J. H.xe2x80x94Proceedings of 20th International Television Symposium, Montreux, June 1997. In COFDM, transmitted data is transmitted over a large number of carrier frequencies (1705 or 6817 for DVB), spaced (by the inverse of the active symbol period) so as to be orthogonal with each other; the data is convolutionally coded, to enable soft-decision (Viterbi) decoding. Metrics for COFDM include Channel State Information (CSI) which represents the degree of confidence in each carrier for reliably transmitting data.
Modulation and Demodulation of the carriers may be carried out by a Fast Fourier Transform (FFT) algorithm performing Discrete Fourier Transform operations. Naturally, various practical problems arise in demodulation in a receiver, firstly in down-converting the transmitted signal in a tuner to a frequency at which demodulation can be carried out, and secondly by accurately demodulating the data from a large number of carriers in a demodulator which is not overly complex or expensive.
In the receiver, frequency offsets may appear after the tuner down-conversation due to oscillator tolerance. Such frequency offset is lethal for signal recovery and frequency has therefore to be tracked by Automatic Frequency Control (AFC). In addition, oscillator phase noise introduces a so-called Common Phase Error (CPE) term, which is a phase offset all carriers bear, and that varies randomly from symbol to symbol. This effect has also to be compensated. Finally, the channel response may not be flat, due to echoes, interferers, and a Channel Equaliser is required to correct for such channel imperfections.
An important consideration in designing a demodulator for incorporation in an integrated circuit chip is reducing the requirements for memory. Bearing in mind the chip may only contain about 1 M Bit of memory, and that signal values for up to about 7000 carrier frequencies may be processed in the chip, this requires tight control over the use of available memory. Certain operations such as Fourier transformation and symbol interleaving require fixed amounts of memory (about 50% of the total). However, other operations such as timing synchronisation, common phase error (CPE) correction, and Channel Equalisation (CE) require some memory but the amount of memory is not fixed.
In our copending application British patent no. 9808992.3, there is claimed an arrangement for reducing memory requirements, including:
transform means for analysing the broadcast signal to provide a series of symbol values for each of the multiplicity of carrier frequencies,
automatic frequency control means for controlling the frequency of said series of signal values in dependence on a common phase error signal from said series of symbol values,
first and second delay means coupled in series to receive said series of symbol values from said transform means, and means for deriving from symbol values in the first and second delay means a common phase error signal,
first and second common phase error correction (CPE) means for receiving said common phase error signal, for correcting said symbol values from said transform means, the output of the first delay means being applied to the first CPE means and the output of the second delay means being applied to said second CPE means,
channel equalisation means for compensating for communication channel impairments for receiving directly the phase error corrected signals from said first CPE means, and third and fourth delay means connected in series and connected to receive the output from said second CPE means and applying delayed versions of the same to the channel equalisation means.
Common phase error requires at least one symbol delay (for each carrier) and channel equalisation may use three symbols delay (for each carrier). However, this arrangement permits the channel equalisation to use only two symbols delay. Whilst this represents a considerable saving in memory, further savings would be desirable.
The present invention is based on the recognition that xe2x80x9cscattered pilotsxe2x80x9d, which form a constituent part of the DVB signal, need not be stored in the channel equalisation step.
Scattered pilots are precisely defined in ETSI standard ETS 300744, para. 4.5.3 and FIG. 11. Put simply, for each of 68 symbols, every 12th carrier (1705 carriers in 2K mode, 6817 carriers in 8K mode) is a scattered pilot signal of boosted power. In successive symbols, the pilot signal positions are incremented by 3 (so that e.g. for symbol S, a pilot is at position k=12, but for symbol S+1, the pilot is at k=15). Scattered pilots are used inter alia for determining the channel response function for channel equalisation. It is not therefore necessary to store them as symbol data. However, because of the rotation of the pilot positions, the pilots cannot simply be deleted from the incoming data without creating confusion and possible loss of data.
Accordingly, the present invention provides in a first aspect, a method of storing symbol data values in a digital video broadcast signal, each symbol comprising a multiplicity of symbol data values including scattered pilot signals, comprising:
providing a write pointer means for writing successive data values for each symbol in successive memory locations, but excluding scattered pilot values, whereby to store symbol data values for at least one symbol,
and providing a read pointer means for reading successive stored data values from successive memory locations, but adding nominal data values at positions of excluded scattered pilots.
In a further aspect, the invention provides apparatus for storing symbol data values in a digital video broadcast signal, each symbol comprising a multiplicity of symbol data values including scattered pilot signals, comprising:
a write pointer means for writing successive data values for each symbol in successive memory locations, but excluding scattered pilot values, for storing symbol data values for at least one symbol,
and a read pointer means for reading successive stored data values from successive memory locations, but adding nominal data values at positions of excluded scatter pilots.
In accordance with the invention, the provision of separate read and write pointer permits the exclusion of scattered pilot signals whilst resolving the problem of maintaining the data values at their correct positions when read from the memory for further processing. A saving of 9% in memory requirements may therefore be achieved, which is a significant saving.
Whilst any number of symbols may be stored, two symbols are the preferred number. The memory locations are preferably stored in a matrix of rows and columns, with a first column storing the first symbol, the data values being entered from a low address to a high address, and any remainder of the first column together with a second column storing the second symbol, with data values being entered from the high address to the low address. In this way, the write pointer continuously circulates around the memory locations, to store the latest two symbols. The read pointer is preferably positioned a predetermined number of memory locations in advance of the write pointer, preferably a minimum of two locations. Thus, the read pointer circulates just in advance of the write pointer, reading stored data just before it is overwritten with new data. The spacing of the pointers permits some variation in their relative position while scattered pilots are excluded, and nominal data subsequently inserted. As preferred, in the initial position of the portions, two memory locations are maintained empty so that writing takes place at the initial position of the read pointer.