A method and apparatus for analyzing the surface characteristics of a sample by Secondary Ion Mass Spectroscopy (SIMS) and Mass Spectroscopy of Recoiled Ions (MSRI) is provided. The method includes detecting back scattered primary ions, low energy ejected species, and high energy ejected species by ion beam surface analysis techniques comprising positioning a ToF SIMS/MSRI mass analyzer at a predetermined angle .theta., where .theta. is the angle between the horizontal axis of the mass analyzer and the undeflected primary ion beam line, and applying a specific voltage to the back ring of the analyzer. Preferably, .theta. is less than or equal to about 120.degree. and, more preferably, equal to 74.degree.. For positive ion analysis, the extractor, lens, and front ring of the reflectron are set at negative high voltages (-HV). The back ring of the reflectron is set at greater than about +700V for MSRI measurements and between the range of about +15 V and about +50V for SIMS measurements. The method further comprises inverting the polarity of the potentials applied to the extractor, lens, front ring, and back ring to obtain negative ion SIMS and/or MSRI data.

Mass spectrometry is an analytical method for quantitatively and qualitatively determining the chemical composition and molecular structure of sample materials. Mass spectrometers are generally comprised of an ion source, a mass analyzer, and a detector. In operation, the sample is positioned in an evacuated area containing the ion source and an ion beam comprised of primary ions is directed at the sample surface. The primary ions collide with the surface species of the sample in accordance with classical collision kinematics, resulting in the back scattering of the primary ions and/or the ejection of surface species from the sample surface. Depending on the angle of incidence, mass of the primary ion beam, and energy of the primary ion beam, the ejected surface species may be comprised of elemental ions, neutral atoms, and/or molecular fragments. The back scattered primary ions and/or ejected species are focused and separated in the mass analyzer and detected by the detector. The energies (velocities) of the back scattered primary ions and ejected surface species correlate with the mass of the surface species and thus are used to identify the chemical composition and structure of the sample surface.
One type of mass analyzer is a linear time-of-flight (ToF) mass analyzer which determines the mass spectra of the surface species by measuring the times for the back scattered primary ions and the ejected surface species to traverse a field-free drift region. The field-free drift region is generally bounded by a drawout grid and an exit grid, which are often at ground potential. The primary back scattered ions and ejected species pass through the drift region and their times of flight are measured by the detector. Mass separation occurs because ions with different masses reach the detector at different times. Pulsing the ion beam, as opposed to directing a continuous beam of ions to the sample surface, allows for a discrete measurement of the back scattered primary ions and the ejected surface species at the detector.
As the primary back scattered ions and ejected species have different initial kinetic energies upon leaving the sample surface, a reflectron is typically used in conjunction with the ToF mass analyzer. The reflectron compensates for the initial kinetic energy distributions by providing a retarding electrical field that reverses the trajectories of the traveling primary ions and ejected species to negate the effects of the uneven kinetic energy distribution and differing velocities. As the ions enter the reflectron, ions with higher kinetic energy and velocity penetrate farther into the reflectron than those ions with lower kinetic energy and velocity, thus traveling a longer path to their focal point. In this way, primary ions and ejected species having the same mass but different initial kinetic energies arrive at the detector simultaneously. The detector counts the incidence of the ejected species. Thus, ToF analyzers including reflectrons can provide a mass spectrum for ejected species over an entire mass range with improved mass resolution verses a linear ToF analyzer.
Ion Scattering Spectroscopy (ISS) is a mass spectroscopy method that measures only the energies of the back scattered primary ions. The primary ion beam strikes the sample surface at about normal incidence, and the back scattered primary ions lose energy according to classical two-body collision kinematics. The surface species are identified by their mass, which is calculated from the arrival time (kinetic energy and velocity) of the back scattered primary ions. The back scattered ion signal is believed to be representative of the composition of the uppermost atomic layer of the sample. Using ISS, all elements heavier than the primary beam can be detected.
Secondary Ion Mass Spectroscopy (SIMS) is a mass spectroscopy method that detects surface species ejected by multiple collisions, also referred to as multiply recoiled or indirect ions, initiated by the incidence of the primary ions from the ion beam on the sample surface. FIG. 1 schematically illustrates SIMS, where the incident primary beam induces a collision cascade in the surface region, which dissipates energy to the lattice atoms through a number of successive biparticle collisions. As some of the cascade returns to the surface, molecular fragments and elemental species are ejected. The ejected surface species have low kinetic energies of less than 20 eV.
Direct Recoil Spectroscopy (DRS), as shown schematically in FIG. 2, is a mass spectroscopy method for measuring the kinetic energies of direct recoil surface species, which are surface species ejected by a single binary collision between a primary ion of the ion beam and a surface atom. DRS directs the primary beam at the sample surface at an angle (grazing incidence), such that binary collisions between the primary ions and the surface species occur, resulting in the direct ejection of surface species in a forward scattering direction, rather than in a collision cascade within the surface region. The energy of the DRS collision causes complete molecular decomposition, and only elemental species (ions and neutrals) are ejected and detected. In contrast to SIMS, the energy of the DRS ejected species is high (200 eV to 6 keV), depending on the scattering geometry, the recoiled mass, the primary ion mass, and the primary ion energy. Mass Spectroscopy of Recoiled Ions (MSRI) is a DRS method that does not measure neutrals, but only the elemental ions, resulting in a higher resolution energy peak for the detected elements.
The method and geometry of ion beam surface analysis (ISS, SIMS, DRS, and MSRI), as shown in FIG. 3, generally consists of directing an ion beam of mass M.sub.1 and kinetic energy E.sub.0 at the surface of the sample, which is comprised of atoms with mass M.sub.2, and detecting the back scattered primary ions with energy E.sub.1 (ISS), multiply recoiled surface species with energy of about 20 eV (SIMS), and/or direct recoil surface species (DRS/MSRI) with energy E.sub.2. For primary ions in the approximate range of between 1 keV and 100 keV, the primary ion-target atom collisions are adequately described by two-body classical collision dynamics. The kinetic energy E.sub.1 of the scattered primary ions is given by EQU E.sub.1 =(1+a).sup.-2 [cos q.sub.1 .+-.(a.sup.2 -sin.sup.2 q.sub.1).sup.1/2 ].sup.2
provided M.sub.2 >M.sub.1. The kinetic energy E.sub.2 of the recoil surface species is EQU E.sub.2 =4a(1+a).sup.-2 cos.sup.2 .theta.
where a=M.sub.2 /M.sub.1 and q.sub.1 and .theta. are the scattering and recoil angles, respectively. As the mass and the velocity of the primary ions of the ion beam are known, and the velocity of the back scattered primary ions and/or ejected species is measurable, the mass of the back scattered primary ions and/or ejected species is determinable from the relationship E=1/2 mv.sup.2.
ToF SIMS instruments measure the times for the primary ions and low energy surface species ejected by the collision cascade to travel through the field-free region. The reflectron analyzer used in high resolution ToF SIMS instruments is positioned with the horizontal axis of the field free region close to the sample surface normal, such that the low energy SIMS ions are ejected into the analyzer. Advantageously, SIMS instruments detect and measure molecular ions and molecular fragments, as well as elemental species, providing valuable qualitative analysis of the chemical composition of the surface. Analysis of the mass data is complicated, however, when molecular species have the same mass as elemental ions (isobaric interferences). For example, C.sub.x H.sub.y molecular fragments prevent the positive identification of N (vs. CH.sub.2), O (vs. CH.sub.4), Al (vs. C.sub.2 H.sub.3), Cr (vs. C.sub.4 H.sub.4), and Fe (vs. C.sub.4 H.sub.8), and, more significantly , especially for the semi-conductor industry, the presence of CO and Si are indistinguishable, as well as Fe.sup.2+ and Si. Charge transfer and neutralization further complicates SIMS analysis. During the ejection of ions from the surface of the sample, a transfer of charge occurs between the surface and the ions, resulting in the neutralization of a portion of the ionic species. The probability of neutralization depends on the local electron density of the surface in the region from which the ion originated and the velocity of the ion as it exits the surface. In SIMS, ions are ejected from the surface with low velocities and kinetic energies, and the probability of ion survival varies by many orders of magnitude, depending on the element being ejected and the oxidation state of the surface. Thus, SIMS instruments measure a small fraction (less than 1%) of a large number surface atoms.
ToF MSRI instruments measure the times for the primary ions and high energy surface species ejected by a single binary collision to travel through the field-free region. MSRI instruments do not measure neutrals, but only the elemental ions, resulting in a higher resolution energy peak for the detected elements than DRS. In addition, MSRI instruments detect all elements with isotopic resolution, including low mass elements (i.e. molecular hydrogen and atomic deuterium) which are indistinguishable by the SIMS method. Since the recoiled MSRI ions have a much larger velocity than the SIMS ions, the MSRI ions are much less subject to neutralization by charge exchange with the surface, and, therefore, MSRI measures a large ion fraction of the ejected species, however, the number of ejected species is small.
Currently, monitoring the surface properties of thin films, especially during the growth of thin films, is critical in technologies involving diamond films, multi-component semiconductor films, and metal and metal oxide films. Thin films are grown under specific conditions, including a low vacuum, high pressure environment. For example, typical conditions for diamond growth include a hydrogen atmosphere, heating, and the allowance for the positioning of film deposition and other instruments. Key factors influencing the surface properties of thin films are the deposition rates of various species, migration of materials at the surface, differences between surface and sub-surface composition, thickness and uniformity of the film, and nucleation of growth sites. For multi-component films, and particularly for multi-component films grown in an atmosphere of oxygen or nitrogen, precise control of the film properties depends on the ability to monitor the growth process as it occurs.
Mass spectroscopy techniques employing low energy pulsed ion beams (less than or equal to 10 keV) are capable of providing a wide range of information directly relevant to the growth of thin films. However, ion beam methods have not been widely used for monitoring thin film growth, because the existing commercial designs and instrumentation are largely unsuitable for the application. For example, in order to characterize the process occurring at the surface of a growing film, the instrument must probe the first few atomic layers and identify the uppermost monolayer where the growth occurs. Most surface analysis methods, however, are unsuitable as in-situ monitors of thin film deposition processes because they require ultra-high vacuum environments, physically obstruct the deposition process, take too long to acquire data, and/or cause significant damage to the film.
One approach for adapting DRS/MSRI instruments to thin film growth applications has been to equip the ion sources and detectors with differential pumping apertures which terminate close to the sample surface, such that the high pressure path traveled by the beam is small. The high velocity of the recoiled MSRI elemental ions allows for surface analysis under high pressure conditions, if both the primary ion source and the detector(s) are differentially pumped. The ability to measure the surface composition with isotopic resolution at high sample pressures makes MSRI suitable for in-situ, real-time monitoring and process control of a variety of thin film deposition processes. SIMS analysis at high pressures, however, is not feasible due to the low velocity of the SIMS ions.
SIMS instruments and MSRI instruments provide complimentary information regarding the chemical composition and structure of the surface of a sample. SIMS provides information about the molecular and elemental species present on the surface of the sample, however, with some complexity regarding the analysis. MSRI provides more quantitative information about elemental species only, and, when used in conjunction with SIMS, can simplify the SIMS analysis. Although there are numerous ToF SIMS instruments utilizing reflectron analyzers, such instruments are not capable of MSRI analysis because MSRI ions have significantly greater energy than SIMS ions and available SIMS ToF instruments are not capable of operating at the high voltages needed for MSRI analysis. Also, the detection of MSRI ions requires an experimental geometry that is different than the geometry used in SIMS ToF measurements.
A need exists in the art for an instrument capable of performing both SIMS and MSRI measurements in a thin film growth environment. The instrument must provide a diverse range of information (composition, structure, growth), be compatible with process conditions (temperature, pressure), be non-destructive to the sample surface, operate in real time, and not interfere with the surface deposition instruments.
The present invention is a ToF SIMS/MSRI reflectron mass analyzer and method that is capable of providing mass spectrum of isotopic resolution for all elements, including hydrogen and helium, using the techniques of both SIMS and MSRI. The use of a single mass analyzer to selectively obtain pure SIMS and/or MSRI spectra is unique and provides valuable, complimentary surface information for sample materials, including thin films.
Therefore, in view of the above, a basic object of the present invention is to provide a ToF SIMS/MSRI reflectron mass analyzer and method capable of performing surface analysis on thin films using both SIMS and MSRI techniques. In addition, MSRI analysis may be performed during thin film growth, in a low vacuum, high pressure environment.
A further object of this invention is to provide a ToF SIMS/MSRI reflectron mass analyzer and method of using a reflectron time of flight analyzer having a critical, optimal geometry, and adjustable reflectron voltages and extraction optics, such that SIMS measurements and MSRI measurements may be accomplished with the same instrument.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of instrumentation and combinations particularly pointed out in the appended claims.

Time-of-flight SIMS/MSRI reflectron mass analyzer and method

The United States of America as represented by the United States Department of Energy


Disclosed is a nucleotide sequence comprising substantially the sequence of nucleotides 229 to 2319 of the sequence shown in FIG. 1 encoding an enzyme having exo-(1.fwdarw.4)-.beta.-D-galactanase activity or a precursor or derivative of such an enzyme, or the functional equivalent of such a sequence. Also disclosed are vectors and hosts comprising the sequence of the invention, and a polypeptide encoded thereby. The nucleotide and amino acid sequences of a functionally equivalent enzyme obtainable from tomato fruit are also disclosed.

Pectin is a major matrix polysaccharide found in the cell wall of plants. Pectins are composed of two distinct regions. The smooth region comprises of long stretches of homogalacturonan interrupted by rhamnose, and is relatively unbranched. The hairy region is rich in galacturonic and rhamnose residues and is highly branched. The side branches contain different sugars but primarily comprise the neutral sugar side chains, arabinan, .beta.-(1.fwdarw.4)-galactan and arabinogalactan. The function of these neutral sugar polysaccnaride side chains has not been fully established. It is speculated that they may function in modulating the pore size of the cell wall and therefore the mobility of proteins, possibly restricting access of various enzymes to their substrates. Moreover, the interaction of the side chains between themselves and with other cell wall polymers could contribute to the structure of the cell wall and the rheoiogical properties of products derived from them. In vitro studies carried out on a solution of apple pectin with different neutral sugar contents demonstrate that increase in branching of pectin results in higher zero-shear viscosity. It was concluded that this was due to pectin side chain interactions. In addition, more branched pectin gives higher elastic or storage moduli (G') than less branched pectin, suggesting that side chain of pectins contribute to elastic properties (Hwang et al., (1993) Food Hydrocolloids 7, 39-53).
The hydrolysis of .beta.-(1.fwdarw.4)-linked galactose from polymeric galactan side chains of pectin has been demonstrated in different plants and in various physiological states (de Vetten and Huber (1990) Physiol. Plant. 78, 447-454; Fischer and Bennett (1991) Ann. Rev. Plant Physiol Plant Mol. Biol. 42, 675-703). During the process of fruit ripening, the loss of the neutral sugar, galactose, is the single most extensive change in the cell walls of many fruits (Fischer and Bennett 1991). Galactose mobilization during fruit ripening has been demonstrated in several fruits including tomato, hot pepper, strawberry, apple, coffee, muskmelon, kiwi fruit, and nectarines. During the senescence of carnation petals, the decrease in cell wall yield is due largely (45%) to a loss of the neutral sugar galactose (de Vetten and Huber 1990). In germinating lupin cotyledons, up to 80% of galactose is mobilized primarily from the .beta.-(1.fwdarw.4)-linked galactan side chains of the rhamnogalacturonan backbone from secondary cell walls adapted to a storage function. A .beta.-galactosidase (exo-(1.fwdarw.4)-.beta.-D-galactanase) would be the enzyme activity predicted to be responsible for galactose mobilization from the galactan side chains of pectin.
.beta.-Galactosidase enzvme activities (including exo-galactanase activities) in plants have been described in the prior art (Dick et al., (1990) Physiol. Plant. 89, 369-375; Burns (1990) Phytochemistry 29, 2425-2429; Singh and Knox. (1985) Phytochemistry 24, 1639-1643; Kundu et al., (1980) Phytochemistry 29, 2079-2082). The purification of some .beta.-galactosidase enzymes has been described, though in many instances synthetic substrates rather than endogenous substrates have been used for enzvme characterization (Ogawa et al., (1990) Nippon Shokuin Kogyo Gakkaishi 37, 298-305; Giannakouros et al., (1991) Physiol. Plant. 82, 413-418). There is evidence that plant .beta.-galactosidases may be associated with developmental processes requiring cell wall turnover, like tissue elongation in Cicer arietinum epicotyl segments. In this tissue, .beta.-galactosidase has been demonstrated to he responsible for autolysis, and the natural substrate of the autolytic reaction is the pectic fraction of the cell wall (Dopico et al., (1989) Physiol. Plant. 75, 458-464; Valero and Labrador (1993) Physiol. Plant. 89, 199-203). A .beta.-galactosidase has been highly purified from the buffer-soluble fraction of carrot cell culture homogenate (Konno et al., (1986) Physiol. Plant. 68, 46-52). The enzyme was active on .beta.-(1.fwdarw.4)-linked galactan prepared from citrus pectin in an exo fashion. The loss of galactose in cell walls during softening has been widely documented (Bartley (1974) Phytochemistry 13, 2107-2111; Redgewell et al., (1992) Plant Physiol. 98, 71-81; Wegrzyn and MacRae (1992) Hort. Sci. 27, 900-902). In tomato, it has been found that the increase in monomeric galactose during fruit ripening is due to an increase in the rate of galactose solubilization from the cell wall rather than changes in the rate of metabolic utilization of the solubilized galactose (Kim et al., (1991) Postharvest Biol. Technol. 1, 67-80). This suggests the action of .beta.-galactosidases in vivo during fruit ripening. There have been several reports of increased .beta.-galactosidase activity during the process of fruit ripening (Bartley 1974; Pressey (1983) Plant Physiol. 71, 132-235; Ross et al., (1993) Planta 1889, 499-506). The .beta.-galactosidase purified from kiwifruit was active in cleaving terminal galactose attached at either the 2, 3, 4 or 6 position (Ross et al., 1993). In tomato fruits, Gross and Wallner (1979, Plant Physiol. 63, 117-120) have shown that decline in wall galactans precedes or accompanies increase in soluble polyuronide. Pressey (1983) has characterized three .beta.-galactosidase activities in ripening tomato fruits of which one (.beta.-galactosidase II), increases 3-fold during ripening. This enzyme was also able to degrade galactan extracted from the cell walls of green tomato and the author suggests a possible role for it in tomato softening. A .beta.-galactosidase has been purified from ripe coffee beans which increases four fold during the transition from immature to ripe fruits (Golden et al., (1993) Phytochemistry 34, 355-360). The enzyme displayed activity against galactan and arabinogalctan, however pectin yielded galactose only in conjunction with an endopolygalacturonase activity.
Solubilization of pectin during fruit ripening is a well-documented phenomenon (Fischer and Bennett, 1991). The action of endopolygalacturonase was considered to be the most likely cause of pectin solubilization, which was thought to be the cause of softening of fruits. Recent studies in transgenic tomato fruits argue against PG being the sole causal agent in the process of fruit softening (Giovannoni et al., (1989) Plant Cell 1, 53-63; Smith et al., (1990) Plant Mol. Biol. 14, 369-379). Recent evidence in fruits with no apparent endo or exo polyalacturonase activity suggests a role for .beta.-galactosidases active on the galactan side chains for the solubilization of pectin (Cutillas-Iturralde el al., (1993) Physiol. Plant. 89, 369-375). Ranawala et al., ((1992) Plant Physiol. 100, 1318-1325) have described a NaCl-released .beta.-galactosidase activity from cell walls of ripe muskmelon (Cucumis melo) fruits, that has the ability to degrade (in vitro) pectin extracted from pre-ripe fruits to smaller sizes of pectin, similar to those observed in ripe fruits. Moreover, there is no detectable PG activity at any stage of muskmelon fruit development and ripening. De Veau et al., (1993 Physiol. Plant. 87, 279-285) have demonstrated increased pectin solubility and decreased apparent molecular weight of pectin extracted from mature green tomato fruits when digested in vitro with .beta.-galactosidases isolated from avocado fruits. Though tomato pectin has been shown to contain at least 10% galactose, only 0.2% was mobilized using avocado derived .beta.-galactosidases. However, this minor change in pectin galactose composition was sufficient to change the solubility of polymeric pectin. These results suggest that an exo-galactanase might play an important role in the pectin solubilization during the process of fruit ripening.
For all the .beta.-galactosidase activities so far described, there are only some indications as to which of the macromolecular components of the cell walls are the actual in vivo substrates. An exception is the .beta.-galactosidase isolated from germinating nasturtium (Tropaeolum majus) cotyledons. The enzyme activity is coincident with xyloglucan mobilization, and the purified enzyme has the unique capability of hydrolysing the terminal .beta.-1,2-linked galactose from the galactoxylosyl sidechain of the xyloglucan polymer (Edwards et al., (1988) J. Biol. Chem. 263, 4333-4337). Buckeridge and Reid recently described (in the printed abstracts of disclosures made at the 6.sup.th Cell Wall Meeting, Nijmegen, Aug. 25-28, 1992, and at the Scottish Cell Wall Group Meeting, April 1993) the purification of a .beta.-galactosidase (an exo-(1.fwdarw.4)-.beta.-D-galactanase) that metabolises the linear .beta.-(1.fwdarw.4)-galactan component of the lupin cotyledonary cell wall. This enzyme is thought to play a key role in the post germinative mobilization of galactan. The enzyme activity is detectable only when galactan mobilization begins, increases during the period of galactan mobilization, and subsequently declines. The changes in exo-galactanase enzyme activity have been shown to correlate with changes in the level of the exo-galactanase enzyme, as determined by immunoblotting. This enzyme is highly specific to .beta.-(1.fwdarw.4)-galactan and does not hydrolyse other plant cell wall polysaccharides known to have terminal non-reducing galactose residues, like nasturtium xyloglucan (terminal (1.fwdarw.2)-.beta.-linked galactose) and larch arabinogalactan (terminal non-reducing (1.fwdarw.3) and (1.fwdarw.6) linked galactose residues.
The enzyme, exo-(1.fwdarw.4)-.beta.-D-galactanase, (which catalyses the hydrolysis of terminal galactose residues from (1.fwdarw.4)-.beta.-linked galactan side chains) appears to have an important role during several physiological processes. The present inventors have achieved the partial protein sequencing, cloning and sequence analysis of a full length cDNA coding for the exo-(1.fwdarw.4)-.beta.-D-galactanase from germinating agricultural lupins (Lupus angustifolius).


An apparatus for controlling at least one function of a motor vehicle has a touch-sensitive input panel. The touch-sensitive input panel includes a transparent material.

The following description relates to an apparatus for the operator control of at least one function of a motor vehicle and/or of at least one appliance installed in a motor vehicle.
An operator control apparatus is described in DE 10 2004 031 659 A1. In this case, an armrest includes a supplementary operator control element which complements an operator control element which is present in the dashboard. The supplementary operator control element may have a transparent touch-sensitive layer, beneath which further parts of the supplementary operator control element are arranged. However, although the touch-sensitive layer of the supplementary operator control element is transparent, it is not possible to perceive the underlying surface beneath the supplementary operator control element.
Another example of an apparatus is described in DE 103 04 704 A1 or DE 103 04 720 A1, for example. Such "touchpads", or touch-sensitive input panels, have recently also found their way into the interior of motor vehicles. In such an application, they can be used for operator control of a wide variety of functions of the motor vehicle or of an appliance installed in the motor vehicle, such as a navigation appliance, for example.
In order to allow appropriate operator control, these operator control panels require a relatively large surface area. However, a large surface area may be regarded as troublesome, particularly in high-end vehicles with correspondingly high-end interior fittings, because the touchpads in some cases require very large areas of the interior trim cut out. This interior trim removal greatly interferes with the aesthetics of the interior of the motor vehicle.

Operator control apparatus in a motor vehicle


A polymer thin film in which cylindrical phases are distributed in a continuous phase and are oriented in a pass-through-direction of the film includes at least: a first block copolymer including at least a block chain A1, as a component of the continuous phase, composed of polymerized monomers a1, and a block chain B1, as a component of the cylindrical phases, composed of polymerized monomers b1; and a second block copolymer including at least a block chain A2, as a component of the continuous phase, composed of polymerized monomers a2, and a block chain B2, as a component of the cylindrical phases, composed of polymerized monomers b2, with the second copolymer having a degree of polymerization different from that of the first copolymer. A film thickness of the polymer thin film and an average center distance between adjacent cylindrical phases have a relation represented by a predetermined expression.

1. Field of the Invention
The present invention relates to a polymer thin film having a microphase-separated structure in which cylindrical phases (a cylindrical microdomain) distributed in a continuous phase are oriented in a pass-through direction of the polymer thin film and provided in a substantially periodic array pattern, and a method of manufacturing the same. The present invention also relates to a patterned substrate having on its surface the periodic array pattern of the microphase-separated structure, and a method of manufacturing the same. The present invention also relates to a patterned medium for magnetic recording manufactured by using the patterned substrate, and a method of manufacturing the same.
2. Description of the Related Art
An electronic device, an energy storage device, and a sensor, or the like have been increasingly reduced in size and have achieved higher performance these years. This requires that a minute periodic array pattern in several nanometers to several hundred nanometers scales be created on a substrate. There is a need for establishing a process of manufacturing a minute pattern with high precision and at low cost. A top-down technique such as lithography is generally used for creating such a minute pattern by minutely cutting a bulk material. For example, photo lithography is typically used in processing a semiconductor such as a LSI.
As a pattern becomes minuter, the top-down technique has more difficulty in terms of an equipment and a process for manufacturing a minute pattern. In particular, if a minute pattern is processed in a several tens nanometers scale or less, the pattern has to be processed using an electron beam or deep ultraviolet rays, which requires an equipment with a large amount of investment. Further, if a pattern is too minute to make it impossible to be created using a mask, a direct writing technique has to be used, which significantly reduces a process throughput.
Under such circumstances, a process applying a self-assembly phenomenon, in which a material organizes a structure by itself, receives much attention. In particular, a process applying the self-assembly phenomenon, a so-called microphase separation, of a block copolymer is excellent in being capable of creating a minute periodic structure having various shapes in tens to hundreds of nanometers scales.
If different polymer block chains constituting a block copolymer are not mixed with each other (incompatible), a specific minute structure having a periodic array pattern is self-assembled thanks to a microphase separation of the polymer block chains.
Techniques of creating a minute periodic pattern using the self-assembly phenomenon have been known, in which, for example, a substrate is etched using a block copolymer composed of a combination such as polystyrene and polybutadiene, polystyrene and polyisoprene, polystyrene and polymethylmethacrylate, as a mask, to thereby create a structure such as a hole, a line and space pattern, or the like (see, for example, "Block Copolymer Lithography Periodic Arrays of ˜1011 Holes in 1 Square Centimeter", M. Park, C. Harrison, P. M. Chaikin, R. A. Register, D. H. Adamson, Science, Vol. 276 (1997) pp. 1401-1404, and "Enabling nanotechnology with self assembled block copolymer patterns", C. Park, J. Yoon, E. L. Thomas, Polymer, Vol. 44 (2003) pp. 6725-6760).
The microphase separation phenomenon of block copolymers enables to obtain a polymer thin film having a structure in which a spherical or cylindrical microdomain is periodically arrayed in a continuous phase.
If the obtained microphase-separated structure is used as a patterned substrate such as an etching mask, it is desirable that cylindrical phases are provided in a period array pattern and are oriented perpendicular to a substrate (in a pass-through direction of the polymer thin film) in a continuous phase.
This is because the structure in which the cylindrical phases are oriented perpendicular to the substrate has a flexibility in changing its aspect ratio, compared to a structure in which a spherical microdomain are provided in a periodic array pattern on a surface of a substrate. The aspect ratio of a domain is a ratio of a size of a domain in perpendicular direction to a substrate, to a size of a domain in parallel to the substrate.
If the microphase-separated structure having the spherical microdomain is used as a patterned substrate for use in an etching mask or the like, its maximum aspect ratio is 1, which is smaller than that of the structure having the cylindrical phases. That is, the structure with the spherical microdomain has smaller control flexibility than that with the cylindrical phases.
Nevertheless, the structure with the cylindrical phases composed of the block copolymers caused by the microphase separation are often oriented parallel to the substrate.
Conventional techniques for orienting the cylindrical phases perpendicular to a substrate (in the pass-through direction of the polymer thin film) are as follows.
A first conventional technique to obtain a microstructure oriented perpendicular to a substrate is that an extremely high electric field is applied to a film composed of block copolymers in a pass-through direction thereof, to thereby orient cylindrical phases thereof in a direction of the electric field (see, for example, "Effect of an Electric Field on Block Copolymer Microstructure", K. Amundson, E. Helfand, D. D. Davis, X. Quan, S. S. Patel, S. D. Smith, Macromolecules, Vol. 24 (1991), pp. 6546-6548).
A second technique is that a surface of a substrate is chemically modified, and is treated to have an equal affinity for each block chain of block copolymers. (see, for example, "Neutrality Conditions for Block Copolymer Systems on Random Copolymer Brush Surfaces", E. Huang, S. Pruzinsky, T. P. Russell, Macromolecules, Vol. 32 (1999), pp. 5299-5303).
A third technique is that a thin film made of a block copolymer composed of three different block chains is formed while inducing a gradual change in a thickness of the film. It has been reported that a microstructure having cylindrical phases oriented perpendicular to a surface of the film are sometimes be created in a region in the film having a specific thicknesses (see, for example, "Phase Behavior in Thin Films of Cylinder-Forming Block Copolymers", A. Knoll, A. Horvat, K. S. Lyakhova, G. Krausch, G. J. A. Sevink, A. V. Zvelindovsky, and R. Magerle, Physical Review Letters, Vol. 89 (2002), No. 3, pp. 035501-1 to 035501-4).
A fourth technique is that, in a technological field of a separation film (a permselective film), a block copolymer composed of polymer chains, which are incompatible with each other, is microphase-separated, and resultant cylindrical phases are selectively removed to obtain a porous film having micropores (see, for example, Japanese Laid-Open Patent Application, Publication No. HEI 5-287084, paragraph 32).
However, the first conventional technique has a problem that, in order to apply the extremely high electric field to the film composed of block copolymers, voltage has to be applied to an extremely narrow gap between a surface of the film and an electrode which are closely contacted with each other.
The second conventional technique has a problem that it is not generally easy to treat the surface of the substrate such that the surface has an equal affinity for each block chain of the block copolymers.
The third conventional technique has a problem that the film is required to have a gradual change in its thickness, which makes it impossible to obtain a substrate having a structure in which the cylindrical phases are uniformly provided over and perpendicular to the substrate.
The conventional techniques above are thus not suitable for providing a structure in which the cylindrical phases are oriented perpendicular to a substrate.
That is, those techniques making use of a microphase separation of block copolymers are still convenient and low in cost to obtain a minute periodic structure in a several tens to several hundreds of nanometers scale. However, the techniques have a difficulty in obtaining the structure having the cylindrical phases perpendicular to a substrate.
The fourth conventional technique has a problem that a periodic array pattern of the cylindrical phases distributed in the continuous phase can be obtained only in a limited portion of the polymer thin film.
The present invention has been made in an attempt to solve the problems described above, and provides a polymer thin film in which the cylindrical phases are extensively provided in a periodic array pattern and in the pass-through direction of the polymer thin film, making use of a microphase separation of the block copolymers. The present invention also provides a method of manufacturing a patterned substrate having on its surface the periodic array pattern of the microphase-separated structure. The present invention also provides a method of mass-producing a patterned medium for magnetic recording capable of, for example, increasing a recording density, by transferring a pattern of the patterned substrate onto the patterned medium.

Polymer thin film, patterned substrate, patterned medium for magnetic recording, and method of manufacturing these articles


A server is provided with operating logic that dynamically migrates or shadows data it shares with its client, in accordance with a migration/shadowing policy that is based on one or more migration/shadowing heuristics. The server is also provided with operating logic that creates the shared data in accordance with a creation policy that is based on one or more creation heuristics. Furthermore, the server is provided with operating logic that maintains the migration/shadowing as well as the creation heuristics in accordance with an update policy. In one embodiment where the data are pixel maps, the migration/shadowing and creation heuristics are corresponding local usage counts, one per pixel map, and a global usage count respectively. The usage counts are incremented and decremented depending on the destinations of the pixel maps of interest.

1. Field of the Invention
The present invention relates to the field of computer systems. More specifically, the present invention relates to art of data management in a networked computing environment.
2. Background Information
Networked client/server computing is known in the art. With recent advances in networking and related technologies, there is increasing interest in networked computing that is even more server reliant than in the past. For example, there is increasing interest in network computing that employs "minimally equipped" clients, with a server providing most of the processing for the "minimally equipped" clients. Particular examples of such "minimally equipped" clients include Explora, manufactured by Networking Computing Devices, Inc. of Mountain View, Calif. assignee of the present invention, and Network Station, sold by IBM of Armonk, N.Y.
Historically, there is little if any coordination in managing data shared by both the server and its clients. Typically, in response to a client's request, a server performs the processing necessary to service the request, and returns the response data, if any, to the client. Upon returning the response data, the server may or may not preserve the response data or any of the working data in anticipation of subsequent requests. Whichever the case may be, the action is taken unilaterally. In the meantime, the client uses the response data as its need dictates. In like manner, the client may or may not preserve the response data, upon "using" it, and the action is also taken unilaterally. In other words, the post response actions of the server and its clients are uncoordinated.
As a result, the response data may be stored in the server only, on both the server as well as the client, or on the client. Depending on the application, each of the three cases may be an inefficient approach to storing the response data. For example, if the application is unlikely to require the response data to be updated, it is inefficient to continue to store the data on the server. It is especially inefficient if the data is stored in the server only, and the same data is required by the client over and over again. Similarly, if the application is likely to require the response data to be updated, it is inefficient to store the data on the client. It is especially inefficient if the data is stored in the client only, and the update operation requires the current state of the data to be provided to the server again.
This problem is especially critical in networked client/server computing involving "minimally equipped" clients that heavily depend on the server, where large volume of data (e.g. pixel maps) are generated by the server and provided to the client, and the likelihood of the server having to update the data can not be predetermined. Thus, a more efficient approach that optimizes the consumption of the computing capacity of the server and the bandwidth available on the network is desired. In view of this and other desired results, the subject data migration/shadowing method and apparatus is invented.

Method and apparatus for migrating/shadowing data between a server and its clients


A process and apparatus for fluidized bed regeneration of FCC catalyst are disclosed. Oxides of nitrogen (NO.sub.x) emissions from an FCC regenerator operating in complete CO combustion mode, and hydrothermal catalyst deactivation, are reduced by reducing the average bed temperature. Dilute phase afterburning superheats catalyst entrained in the dilute phase region above the fluidized bed. Cyclone separators recover superheated, entrained catalyst and preferentially recycle this catalyst to the FCC reactor, permitting cooler operation of the dense phase fluidized bed.

1. Field of the Invention
The invention relates to catalytic reduction of oxides of nitrogen, NO.sub.x, produced in catalytic cracking unit regenerators operating in complete CO combustion mode.
2. Description of Related Art
NO.sub.x, or oxides of nitrogen, in flue gas streams from FCC regenerators operating in complete CO burn mode is a pervasive problem. FCC units process heavy feeds containing nitrogen compounds, and much of this material is eventually converted into NO.sub.x emissions. There may be some nitrogen fixation, or conversion of nitrogen in regenerator air to NO.sub.x, but most of the NO.sub.x in the regenerator flue gas is believed to come from oxidation of nitrogen compounds in the feed.
Several powerful ways have been developed to deal with the problem. The approaches fall into roughly five categories:
1. Feed hydrotreating, to keep NO.sub.x precursors from the FCC unit.
2. Segregated cracking of fresh feed.
3. Process approaches which reduce the amount of NO.sub.x formed in a regenerator via regenerator modifications.
4. Catalytic approaches, using a catalyst or additive which is compatible with the FCC reactor, which suppress NO.sub.x formation or catalyze its reduction.
5. Stack gas cleanup methods which are isolated from the FCC process.
The FCC process will be briefly reviewed, followed by a review of the state of the art in reducing NO.sub.x emissions, and hydrothermal catalyst deactivation.

Low NO.sub.x FCC regeneration process and apparatus


A storage system includes an elongated, generally rectangular housing which has a forward-facing surface in the vehicle defining the rear seat backs of a vehicle and which has an open opposite end for extending into the trunk of a vehicle. The housing is slidably mounted to move from a retracted position substantially within the vehicle trunk in which the forward-facing surface defines the rear seat back rests of the rear passenger area of a vehicle and an extended position in which the generally rectangular housing is moved forwardly to expand the available storage space within the trunk. In a preferred embodiment of the invention, the generally rectangular storage housing includes at least one pivoted access door such that access can be obtained to the rectangular storage housing from within the rear seat passenger area of the vehicle. In a preferred embodiment of the invention, the access means includes a pivoted top lid. In another preferred embodiment of the invention, the storage system further includes a pivoted forward-facing door to provide direct access to the trunk regardless of the position of the storage housing.

The present invention relates to a storage system for a vehicle, such as an automobile, and particularly one which provides an expanded trunk storage area.
There exists a variety of vehicle storage systems in which the rear seat backs of a vehicle can be pivoted to allow trunk access for storage of large items. Recently, for example, commercial vehicles have included a center rear armrest which can be opened to provide a storage bag extending into the rear passenger area through the trunk for the storage of elongated items such as skis. U.S. Pat. No. 2,140,968 discloses a system in which the rear seats and back of a vehicle can be moved to extend the trunk storage area into the rear seat area. Although providing the desired expansion of the trunk storage area into the rear seat passenger area, the items to be stored in the expanded trunk space are readily visible and contact the seating surfaces of the rear seat area. It is desired, therefore, to provide a storage system which expands the trunk storage area and provides a secure and attractive expanded storage area, and one which is accessible not only from the trunk but also from the rear passenger seat area of the vehicle.


A microphone assembly includes a microphone unit and an attachment unit. The attachment unit includes a camera shoe attachment section. A camera shoe extension includes a support arm and a camera shoe attachment section attached to a rear end of the support arm. The support arm is curved into a circular arc shape such that the front end thereof is located higher than the rear end thereof. The camera shoe attachment section of the attachment unit is mounted on a shoe formed on the front end of the support arm. The camera shoe attachment section of the camera shoe extension is mounted on a camera shoe of a digital camera.

Technical Field
The present invention relates to a camera shoe extension which is detachably attached to a camera shoe of a digital camera and holds an accessory.
Description of the Related Art
A camera shoe is formed on a camera body of a digital camera such that an accessory such as a flash device and a microphone assembly can be detachably attached to the camera body. For example, according to Japanese unexamined utility model application publication No. 2-051494 and Japanese examined utility model application publication No. 7-003750, it is described that a microphone assembly is detachably attached to a camera shoe.
Since a camera and a lens device are provided with various motors, operating noise of the motors, noise of moving members driven by the motors, and the like are generated during image capturing. In order to surely prevent generation of such operating noise and the like, it is necessary to keep an adequate distance between the microphone assembly and the camera body. However, according to Japanese unexamined utility model application publication No. 2-051494 and Japanese examined utility model application publication No. 7-003750, the microphone assembly is attached to the camera shoe formed on the camera body, and therefore it becomes impossible to keep an adequate distance between the microphone assembly and the camera body.
Moreover, it is known that the flash device causes a so-called red-eye effect in which pupils of a subject appear red in the case where the flash device is located near a taking lens. In order to prevent such a red-eye effect, it is only necessary to keep the flash device away from the camera body. However, the flash device is mounted on the camera shoe of the camera body, and therefore it becomes impossible to keep an adequate distance between the flash device and the camera body.


An active limiting system that is suitable to protect a low noise amplifier against the high power signals received from a signal input includes, at least one first switch, source of which is connected to a gate voltage; at least first resistor which is connected between the gate and source of the first switch; at least one second resistor, which is connected between a drain voltage and drain of the first switch; at least one second switch, source of which is connected to said drain voltage and drain of which is connected to a signal input; at least one third resistor which is connected between the drain of the first switch and gate of the second switch; at least one first filtering element, which blocks DC currents/voltages and which is connected between the source of the second switch and ground.

Low noise amplifiers (LNA) are electronic amplifiers that amplify the power level of low power signals. While the low noise amplifiers amplify the power level of the signal, they keep the noise level of the output signal as low as possible. In order to perform such amplification, low noise amplifiers usually comprise at least one transistor (such as HEMT).
Low noise amplifiers are generally used in radio communications systems. Since radio communication usually deals with low power signals (especially at the receiving end) low noise amplifiers used for the amplifying the power level of said low power signals. In the low noise amplifiers, in order to reduce the noise, sensitive components are used. Although said sensitive components are effective for reducing the noise level, they are generally vulnerable to the high power inputs. Although in the ideal cases, no high power signal is sent to the low noise amplifiers, it is possible that low noise amplifiers may be exposed to high power signals. For example in the radar applications, transmitted power may be reflected from antenna and low noise amplifier can be exposed to reflected high power through circulator. In another example, an electromagnetic bomb may generate high power signals to destroy the low noise amplifier.
Since low noise amplifiers are vulnerable against the high power signals, in the known art different protection systems are used for protecting the low noise amplifiers against the high power signals. One of the protection systems used in the known art is passive limiting circuits. An exemplary embodiment of said passive limiting circuits is disclosed in the paper Jim Looney et al. "An Examination of Recovery Time of an Integrated Limiter/LNA". Said passive limiting circuits comprise protecting elements that limit the voltage level of the input of the low noise amplifiers. Although said passive limiting systems limit the input power, they cause high noise levels. Therefore, when low noise is needed, said passive limiting systems are not preferred.

ASELSAN ELEKTRONIK SANAYI VE TICARET ANONIM SIRKETI


An equipment tracking system that provides for configuration management control over a plurality of pieces of equipment. The system includes a plurality of sets of sensors, a plurality of collectors, each individually coupled to a selected set of sensors, a concentrator coupled to the plurality of collectors, and a computer having a database for storing sensor data is coupled to the concentrator by way of a communication link. Each sensor is attached to a piece of equipment, and each sensor has a unique ID code. Each collector is coupled to a selected set of sensors, and is adapted to read out the ID code of each of the sensors at selected times, and store the changes for those sensors that have changed since the prior reading. The concentrator communicates with the plurality of collectors and causes the collectors to transmit the changed information. The present invention provides a non-manpower intensive system for providing current and accurate configuration management of thousands of pieces of equipment in a geographically dispersed environment. The present invention provides an automated system that instantaneously detects both authorized and non-authorized changes to a physical hardware configuration of a geographically dispersed equipment environment. It automatically communicates configuration change information to a centralized database which correlates the changes. The system accounts for operational interrupts such as power and hardware failures, provides for information importing from external databases using property tag identifiers, and provides for report generation using the internal and external databases.

The present invention relates to equipment tracking systems, and more particularly, to an equipment tracking system that provides current and accurate configuration management information regarding the physical status of computer-related equipment.
The assignee of the present invention currently has the responsibility for the hardware and software engineering, installations and maintenance of institutional personal computers and their peripheral equipment (including data communications equipment). This equipment is dispersed in many offices across many on-site and off-site facilities. Crucial to providing effective and efficient engineering, installation and maintenance services is the existence of current and accurate configuration information. Such information has not heretofore existed. What does exist are heavily manpower dependent processes that produce a mainframe database that provides stale, inaccurate and incomplete information. Some of the contributors to this yield includes multiple transcribing/data entry (each a point for introducing error), multiple process queues (located in paperwork or a data entry queue), and the reliance upon someone to accurately report the physical changes.
Previous attempts at improving configuration management, focused upon what can be done to the existing processes to make them better in terms of accuracy, timeliness, and cost effectiveness. Many "business-as-usual" efforts have resulted in many sub-optimizations of the existing configuration management system. Collectively, they have not measurably improved the configuration management (CM) system, because they have not modeled the configuration management maintenance process (chain of significant events) and evaluated existing tools capabilities relative to that process.
A model of the configuration management system is shown in the table below.
__________________________________________________________________________ /--------------------------------------------time------------------------- --------------------------> __________________________________________________________________________ Hardware Change --> Report the Change --> Update CM Database --> Do for Next Authorized Manual by configur- Multiple responsible By Service ation sheets Information duplicated Request (SR) Multiple handoffs across multiple databases By Maintenance Prob- Reported out of time Found by accident lem Request (MPR) sequence (controlled/owned by others) Unauthorized Updating is an add-on function (not part of the change process) __________________________________________________________________________
With the existing system there is no way, other than by chance or a physical audit, to detect an unauthorized configuration change. Even if a change is detected, the configuration management system requires many functional and organizational hand-offs from the first step in the reporting process to the final step in the database update process. Each handoff involves manual transcription (chance for errors) of the source information. Procedurally, everyone is responsible; therefore no one is responsible. Everyone does their best, but no one can perform better than the system permits. Armed with this knowledge, it was determined that a system engineering approach must be taken to the entire system and philosophy of configuration management in a distributed environment.
Fundamental to effective configuration management is current and accurate data collection for all changes to the equipment configuration. Data collection includes detecting the change, reporting the change, and updating the change into a configuration management database. For the purposes of the present invention, automation is defined as the automatic operation or control of a process, equipment, or a system. It is further defined as the techniques and equipment used to bring about automatic operation or control of a process or system. It has been found that simply migrating part or all of a given work function to an electronic data processing or computer environment does not constitute automation. Therefore, simply using electronic data processing hardware, software and databases does not constitute automation.
The purpose of using automation is to perform a process more efficiently and effectively than it could be accomplished manually. Where a process for achieving an aim already exists, the proper implementation of automation must yield measurable cost and/or time savings over the manual approach for that process and must not detract from the product's quality. The present invention achieves automation of an automated configuration management system by using electronic data processing as an in-line (integral) tool that contributes directly to the process.
U.S. Pat. No. 3,766,540 issued to Schopfer et al., for "Appliance Removal Alarm System for Motels" describes a system whose primary function is to detect disconnected devices. It lacks the ability for a relocated unit to report its new location. This system does not provide for history logging of disconnected/relocated equipment nor does it provide the capacity to query individual locations (rooms/areas) for the ID numbers of equipment located at that location.
U.S. Pat. No. 4,920,488 issued to Filley, for "Physical Inventory System" is a non-real time location system. This system requires that each tracked item be labeled with a bar code which is scanned at random intervals. This system's configuration data is valid only until the first piece of equipment is moved and is not valid again until the next time the facility is scanned. This system does not provide for continuous scanning and recording of the configuration of the equipment, with no human intervention required.
U.S. Pat. No. 4,141,078 issued to Bridges, Jr. et al., for "Library Circulation Control System" uses similar techniques and is generally the same as the system of U.S. Pat. No. 4,920,488.
U.S. Pat. No. 5,038,320 issued to Health et al., for "Computer System with Automatic Initialization of Pluggable Option Cards" describes a system that is used to control and configure the internal interface boards in devices such as personal computers, workstations and minicomputers. It provides no method of tracking the individual ID numbers of peripheral devices such as printers modems, terminals or units not connected a local area network. This system does not provide for universal tracking of equipment without requiring connectivity of the unit to any networks. This system could be configured to limit operation if a particular peripheral device is attached to another system. This system does not provide for automated equipment tracking that is transparent to the user, allowing for free movement and reconfiguration of the hardware.
U.S. Pat. No. 4,862,355 issued to Neumann et al., for "System Permitting Peripheral Interchangeability During System Operation" describes a system that is used to buffer and distribute data between various types of CPU's and peripherals. It provides no configuration control, management capability, or monitoring. It also lacks remote sensing capability.
U.S. Pat. No. 4,636,950 issued to Caswell, for "Inventory Management System Using Transponders Associated with Specific Products" most closely resembles the present invention. The theory of operation and scan characteristics, however, are very different than those of the present invention. This prior art invention is designed to scan for a certain element ID or group of ID's. The operator sets the scanner to search for a series of ID's until an acknowledgement signal is received from an inventory item with a transceiver preprogrammed with the ID number.
This system requires that each transceiver be programmed with all current transceiver numbers. This system can tell what equipment is located in a room when that equipment was installed, but it cannot recognize and report the identity of equipment which the user relocates into another room. This system cannot be used to determine which CPU is attached to which monitor and printer. The invention described in this patent does not have this ability to determine immediately the detailed inventory of a particular workstation. The invention described in this patent does can only tell the operator what equipment is in an area. This invention is used to track "high-value products e.g. a motorcycle or the like . . ." which would imply that the unit cost may be rather high. It also uses RF transmission which is not suitable for Federal Government facilities, for example, where highly sensitive equipment can be operationally contaminated by stray signal transmissions and where secrecy considerations are required. This system also requires the modification of the manufacturing process of the equipment to be tracked and does not appear to be universally adaptable to all types of devices.


A device for sealing a penetration in a pressurizer of a nuclear steam supply system includes a hollow cylinder adapted to be inserted into the heater sleeve, in place of the heater. The cylinder includes a nose portion formed with a number of axially extending slots defining therein a number of radially displaceable segments, each of which has an outwardly extending flange, proximate its distal end, which is engageable with the heater sleeve to resist blowout. A rod, inserted into the cylinder, seals the passage therethrough while locking the displaceable nose portion segments in their sleeve-engaging position. An annular soft nickel band on the outside of the cylinder engages the inner surface of the heater sleeve to provide an effective seal therebetween.

The present invention pertains to nuclear steam supply systems (NSSS) and, more particularly, to a device for sealing a penetration in a pressurizer for such a system.
In a nuclear steam supply system, the pressurizer maintains reactor coolant system operating pressure and, in conjunction with the chemical and volume control system, compensates for changes in reactor coolant volume during load changes, heatup, and cooldown. During full-power operation, the pressurizer is about one-half full of saturated steam. Reactor coolant system pressure may be controlled automatically or manually by maintaining the temperature of the pressurizer fluid at the saturation temperature corresponding to the desired system pressure.
Typically, the pressurizer is a cylindrical pressure vessel, vertically mounted and bottom supported. A small continuous spray flow is maintained in the pressurizer to avoid stratification of the pressurizer boron concentration and to maintain the temperature in the surge and spray lines. Energy is supplied to the water by replaceable, direct-immersion, electric heaters which are inserted from the bottom head of the pressurizer. A number of the heaters are connected to proportional controllers which adjust the heat input to account for steady-state losses and to maintain the desired steam pressure in the pressurizer.
The individual heaters are carried in tubular heater sleeves which are sealingly attached to the pressurizer pressure vessel. In the event that a leak develops in one of the heater sleeves, means must be available to quickly and effectively seal the leak, to prevent the escape of radioactive water, while the system remains in operation.
It is, therefore, a primary object of the present invention to provide a device for sealing a penetration in a pressurizer for a nuclear steam supply system and, more particularly, a leak associated with a pressurizer heater sleeve.
It is a further object to provide such a sealing device which may be quickly and effectively utilized to seal such a leak while the system remains in operation.
These and other objects and advantages of the invention as may hereinafter appear are achieved by a sealing device including a hollow cylinder adapted to be inserted into the tubular heater sleeve, in place of the heater. The cylinder includes a nose portion formed with a plurality of axially extending slots defining therein a number of radially displaceable segments, each of which has an outwardly extending flange, proximate its distal end, which is engageable with the heater sleeve to resist blowout. A rod, inserted into the cylinder, seals the passage therethrough while locking the displaceable nose portion segments in their sleeve-engaging position.
Advantageously, the cylinder is formed of a nickel alloy and includes an annular band of soft nickel on its external surface which engages the inner surface of the heater sleeve to provide an effective seal therebetween.

Pressure vessel penetration sealing device


The present invention describes a training and communicating device for the domestic animals to allow the pets to signal their owners/trainers that they need to go outdoors for fresh air or toileting needs. The training and communicating device for the domestic animals comprises of a paw shaped device having pads containing the sensors inside which when touched by the pets, sends the signal to a voice activated monitor, which in turn transmits the signal to the owners/trainers that the pets need them. The device can also be used along with the smartphone for remotely operating the pet doors. A mobile application has to be installed in the smartphone and the pet's paw has to be registered with the device, which sends notification to smartphones whenever the pets send signals. The device also provides facilities like warming, massaging or even cleaning the paws of the pets.

The pets generally stay indoors in their respective houses along with the owners or trainers. Usually the owners/trainers of the pets often follow a routine where the pets are taken outdoors in order to provide them fresh air, or attend their toileting needs. Because of the busy schedules of the owners/trainers, sometimes such needs of the pets are forgot or unattended which can be unhygienic for both pets as well as the owners/trainers. The pets have to be allowed to breathe in the fresh air to keep them healthy.
The owners/trainers follow a routine where the pets have to be taken out at regular intervals to fulfil their needs. For example, many pets are well trained to relieve themselves only in the outdoors and so must be given frequent access to the outdoors according to the pet's biological needs. The owners might have provided the pet with the pet doors that allow the pets to go outdoor and come back home by itself as per its wish. There are certain devices also developed to assist the pets for the same purpose. But such devices also comes with several disadvantages which might let other animals, other than pets to enter the home which might lead to many problems. Another disadvantage which is accompanied by such devices is that, the devices has to be installed at the doors of the home which might require permanent alteration to the doors which is not possible in case of rented houses or apartments who would not allow such requests. The automatic systems can only open and close the doors for the pets, but cannot take care of the time spent by the pets in outdoors. And also in bad weather conditions, the pets need to be kept inside for their safety, which cannot be monitored by the automatic systems.
Because of these shortcomings of the available devices, the owners/trainers prefer to take the pets outdoors personally whenever the pets wish. But because of busy schedules, they might not be able to attend the pets personally every time in a day when the pet wishes to go outdoors. In such cases, the pets might become angry and impatient, leading behavioural changes such as severe barking, attacking the owner/trainer to scratch them or to scratch the door etc. Such situations of distress can create problems to pets, owner/trainers and neighbours as well.
Several systems and devices have been developed for the same purpose which are described below.
A state of the art U.S. Pat. No. 7,057,515B2 describes a Pet-activated signalling assembly which discloses a pet-activated signalling device allowing the pet to signal a human includes a base, and a cover, associated with the base. A biasing element is operatively coupled between the base and the cover and is configured to provide a positive biasing force there between. At least one audio signalling system is associated with the base and the cover and is activated in response to relative movement of the cover with respect to the base. At least one visual signalling system is associated with the base and the cover and is activated in response to relative movement of the cover with respect to the base.
Another state of the art U.S. Pat. No. 5,038,703A illustrates a Device and method to aid in toilet training pets, which discloses a training and communicating device for domestic animals which is mountable to a doorknob or other mounting element on or near a door. An elongated leather strip is provided with an aperture for removably suspending the strip from a doorknob. The strip also has a plurality of pairs of holes for securing through each pair of holes a sleigh bell onto the strip with vinyl lacing. The strip, with bells attached and suspended on or near the door within reach of an animal, produces sound when struck by the animal that may be heard throughout an average-sized home.
Another state of the art U.S. Pat. No. 4,400,696A illustrates an Animal actuated attention attracting apparatus enabling animals to attract attention of a keeper thereof when the animal desires to obtain entrance into a house or other building comprising a door mounted contact and wire feed through element, and adjustable hinged outside door mounted panel member, and adjustable contact member mounted on the hinged panel member for contact with the door mounted contact when the panel member is actuated, adjustable tension means for normally maintaining the hinged panel member in an unactuated contact position, an inside door mounted container provided with appropriate electrical energisation, wiring, and both visual and audible attention attracting elements, and a multiple position switch for permitting selection of the desired attention attracting element when the panel member is actuated by an animal.
The signally devices described in the state of the art patents can be activated by the pets and are being used by most of the users, which fairly allows the pets to indicate its desire to go outdoors or come back home. As explained earlier, the main shortcoming of such devices is the permanent alteration to be made for the door while installation which is not practical as well as economical because of the time and resources required for installation and several other complications. Also these devices can be used only at home as they are fixed. Also the signalling devices generally use audio signalling device that is remote from the signalling assembly which is expensive and complicated with high number of components. The cost of maintenance is also high if any component of the device gets damaged.
Therefore there is a need for an advanced device to aid the pets in potty training, where the pet signals the owner/trainer indicating that it wants to go outdoors to the bathroom or for fresh air. There is a need for a device that can also help those who has memory issues, so that the device indicates the need of the owner for the pets.


A network interface device couples a host computer to a network. The network interface device includes a processor and a DMA controller. The processor causes the DMA controller to perform multiple DMA commands before the processor takes a particular software branch. The processor issues the DMA commands by placing the DMA commands in a memory and then pushing values indicative of the DMA commands onto a DMA command queue. The values are popped off the DMA command queue and are executed by the DMA controller one at a time. The DMA commands are executed in the same order that they were issued by the processor. The processor need not monitor multiple DMA commands to make sure they have all been completed before the software branch is taken, but rather the processor pops a DMA command complete queue to make sure that the last of the DMA commands has been completed.

FIG. 1 (Prior Art) is a diagram of a network interface device (NID) 100 that couples a host computer 101 to a network 102. The particular NID 100 of FIG. 1 is an expansion card that is coupled to host computer 101 via PCI bus 103. NID 100 includes an integrated circuit 104, physical layer interface circuitry 105, and dynamic random access memory (DRAM) 106. Integrated circuit 104 includes a media access controller 107, queue manager hardware 108, a processor 109, sequencers 110, an SRAM controller 111, static random access memory (SRAM) 112, a DRAM controller 113, a PCI bus interface 114, a DMA controller 115, a DMA command register 116, and a DMA command complete register 117. For additional detail on one such integrated circuit 104, see U.S. patent application Ser. No. 09/464,283, filed Dec. 15, 1999 (the subject matter of which is incorporated herein by reference).
In one example, NID 100 is used to retrieve three portions of data 118–120 from host storage 121 and to output them to network 102 in the form of a data payload of a packet. In the situation where the three portions 118–120 are stored on different pages in host storage 121, it may be necessary to move the data to DRAM 106 individually. The three portions 118–120 are to all be present in DRAM 106 before packet transmission begins.
In the device of FIG. 1, processor 109 causes DMA controller 115 to execute DMA commands 122 by placing the DMA commands into SRAM 112 via lines 123 and SRAM controller 111. Once a DMA command is present in SRAM 112, processor 109 instructs the DMA controller to fetch and execute the DMA command by setting a bit in DMA command register 116. A DMA command includes a source address for data to be moved, a destination address for data to be moved, and a byte count. In the example of FIG. 1, there can be thirty-two pending DMA commands 122 stored in SRAM 112. Consequently, there are thirty-two bits in DMA register 116. DMA controller 115 fetches the command, executes the command, and then sets a corresponding bit in 32-bit DMA command complete register 117. Processor 109 monitors the bit in the DMA command complete register 117 to determine when the DMA command has been completed.
In the example of FIG. 1, each of the three data portions 118–120 is moved into DRAM 106 in two moves. In a first move, the data is moved from host storage 121 and to a buffer in SRAM 112. In a second move, the data is moved from the buffer in SRAM 112 and to DRAM 106.
To move the first portion of data 118 from host storage 121 to DRAM 106, processor 109 writes a DMA command into SRAM 112. DMA controller 115 retrieves the DMA command from SRAM 112 via SRAM controller 111 and lines 124. DMA controller 115 then executes the command by sending a request to PCI bus interface 114 via lines 125. PCI bus interface 114 responds by retrieving data 118 from a particular address X1 and supplying that data to SRAM controller 111 via lines 126. PCI bus interface 114 reports completion of this action by returning an acknowledge signal to DMA controller 115 via line 127. SRAM controller 111 writes the data into the buffer in SRAM 112. DMA controller 115 then issues a request to DRAM controller 113 via lines 128. Data from SRAM 112 is then transferred via SRAM controller 111, lines 129, and DRAM controller 113 to a location 130 (address Z1) in DRAM 106. When this action is complete, DRAM controller 113 returns an acknowledge signal to DMA controller 115 via line 131. DMA controller 115 sets a bit corresponding to this completed DMA command in the DMA command complete register 117. In this way, each of the three portions of data 118–120 is moved through SRAM 112 and into DRAM 106. Although the three data portions are illustrated being stored in DRAM 106 at different locations Z1, Z2 and Z3, this need not be the case. All three data portions are sometimes stored in one continuous block.
In the particular NID 100 of FIG. 1, DMA controller 115 may execute DMA commands in an order different from the order in which the DMA commands were placed in SRAM 112 by processor 109. For example, while DMA controller 115 is moving the first portion 118 to DRAM 106, the processor 109 may place additional DMA commands into SRAM 112. When DMA controller 115 finishes moving first portion 118, the DMA controller 115 may fetch a DMA command to move the third portion 120 next. Because all three data portions 118–120 are to be in DRAM 106 before transmission of the packet begins, processor 109 cannot only check that the last move in the sequence is completed. Rather, processor 109 must check to make sure that all the moves are completed before processor 109 goes on in its software to execute the instructions that cause the ultimate packet to be formed and output from NID 100.

Network interface device employing a DMA command queue


Antacid powders, tablets etc. of prolonged gastric residence time have an internal phase of a solid antacid and excipient surrounded by a solid external phase containing a hydrophobic substance e.g. an ester of glycerol with palmitic or stearic acid, a hydroxylated polyalkene and a non-ionic emulsifier.

1. Field of the Invention
This invention relates to antacid compositions having a prolonged gastric residence time.
2. Technical Review
Classical antacids such as aluminium and magnesium hydroxide gels and co-gels and the new crystalline aluminium magnesium hydroxycarbonates or sulphates such as Hydrotalcite, Almagate and Magaldrate are either rapidly neutralized to water soluble ions or sediment in the fundus of the stomach, and are evacuated into the duodenum by normal peristalsis with subsequent loss of unused drug from its site of action. Consequently they do not neutralize the continuous output of hydrochloric acid by the parietal cells in the human stomach for a prolonged period of time.

Antacid compositions with prolonged gastric residence time


Systems and methods for automated non-destructive inspection scanning of the top and bottom aerodynamic surfaces or skins of an integrally stiffened wing box (e.g., a horizontal stabilizer) using surface crawling vehicles. Each system uses dynamically controlled magnetic coupling to couple an external drive tractor to a pair of passive trailers disposed in the interior of the wing box on opposite sides of a spar. The external drive tractor is also coupled to an external NDI scanner, which the tractor pushes or pulls across the surface skin being inspected. The systems allow scanning of both surface skins without turning the wing box over. Each system is modular and can be transported to and easily set up in a building or factory.

The present disclosure relates generally to the field of automated maintenance (including non-destructive inspection) of aircraft structural elements, and more particularly to an automated end effector-carrying apparatus that is coupled to and travels along an integrally stiffened wing box while performing a maintenance function. As used herein, the term "maintenance" includes, but is not limited to, operations such as non-destructive inspection (NDI), visual inspection, drilling, scarfing, grinding (e.g., to remove bonded or bolted components), fastening, appliqué application, ply mapping, depainting, cleaning and painting.
A variety of elongated composite structures may have relatively confined internal cavities that require inspection in order to assure that the structure meets production and/or performance specifications. One known elongated composite structure with tapering internal cavities is an integrally stiffened wing box for an airplane. One example application is in the horizontal stabilizer of an aircraft. A horizontal stabilizer structural box may be fabricated as a large co-cured structure that requires the use of soft internal tools to facilitate tool removal after the cure. If a given co-cured composite structure is considered primary structure, it would therefore need to be inspected to ensure structural integrity.
One of the requirements for certification of a composite-based airplane horizontal stabilizer is to perform a complete set of NDI scan of all the composite structural elements. Methods for scanning the interior surfaces of a horizontal stabilizer using a modular, magnetically coupled transporter system have been disclosed, for example, in U.S. patent application Ser. No. 13/534,014. With regard to the exterior surfaces of a horizontal stabilizer, it is known to use a large gantry mechanism that moves an ultrasonic maintenance tool over a surface skin. This gantry-based system is expensive, requires extensive training to operate, and occupies a large space, which limits the flexibility in setting up NDI work cells for scanning of horizontal stabilizers It also requires that the horizontal stabilizer be turned over to scan the opposite surface.
It would be desirable if a process were available that could scan wing box surface skins without the need for a gantry-based mechanism for movement of the NDI sensor array. An additional benefit would be if the surface skin scanning process were compatible with the aforementioned process for scanning the interior surfaces. Accordingly, there is a need for a system for inspecting the exterior of a wing box and similar elongated hollow structures that can provide such benefits.

System and method for scanning a wing box skin


Method is disclosed for determining characteristics of a toner cartridge. One aspect is directed to determining the characteristics associated with a quantity of toner in the cartridge, and thus, the method includes the steps directed to determining a home position of an encoded device relative to a code reader, determining a delay in rotational movement of the encoded device with respect to a rotational movement of a drive mechanism as an agitator moves through the toner, and translating the delay into an amount of toner remaining in the cartridge. Another aspect is directed to determining preselected cartridge characteristics from the encoded device, and thus, the method includes steps directed to rotating the encoded device, reading a coding of the encoded device, and decoding the coding to determine the preselected cartridge characteristic information represented by the coding. The method steps directed to these aspects of the method may be performed separately or in aggregate.

1. Field of the Invention
The present invention relates to Electrophotographic (EP) machines and more particularly relates to methods and apparatus associated with replaceable supply cartridges for such machines wherein information concerning the cartridge is provided to the machine to promote correct and efficient operation thereof.
2. Description of Related Art
Many Electrophotographic output device (e.g., laser printers, copiers, fax machines etc.) manufacturers such as Lexmark International, Inc., have traditionally required information about the EP cartridge to be available to the output device such that the control of the machine can be altered to yield the best print quality and longest cartridge life.
The art is replete with devices or entry methods to inform the EP machine about specific EP cartridge characteristics. For example, U.S. Pat. No. 5,208,631 issued on May 4, 1993, discloses a technique to identify calorimetric properties of toner contained within a cartridge in a reproduction machine by imbedding in a PROM within the cartridge specific coordinates of a color coordinate system for mapping color data.
In other prior art, for example U.S. Pat. No. 5,289,242 issued on Feb. 22, 1994, there is disclosed a method and system for indicating the type of toner print cartridge which has been loaded into an EP printer. Essentially, this comprises a conductive strip mounted on the cartridge for mating with contacts in the machine when the lid or cover is closed. The sensor is a two position switch which tells the user the type of print cartridge which has been loaded into the printer. While this method is effective, the amount of information that can be provided to the machine is limited.
In still other prior art, such as in U.S. Pat. No. 5,365,312 issued on Nov. 15, 1994, a memory chip containing information about the current fill status or other status data is retained. The depleted status of print medium is supplied by counting consumption empirically. The average of how much toner is required for toning a charge image is multiplied by the number of revolutions of the charge image carrier or by the degree of inking of the characters via an optical sensor. In either method, the count is less than accurate and depends upon average ink coverage on the page, or alternatively, the character density which can change dramatically due to font selection. Therefore at best, the consumption count lacks accuracy.
The literature suggests several methods for detecting toner level in a laser printer. Most of these methods detect a low toner condition or whether toner is above or below a fixed level. Few methods or apparatus effectively measure the amount of unused toner remaining. As an example, Lexmark.RTM. printers currently employ an optical technique to detect a low toner condition. This method attempts to pass a beam of light through a section of the toner reservoir onto a photo sensor. Toner blocks the beam until its level drops below a preset height.
Another common method measures the effect of toner on a rotating agitator or toner paddle which stirs and moves the toner over a sill to present it to a toner adder roll, then developer roll and ultimately the PC Dnim. The paddle's axis of rotation is horizontal. As it proceeds through it's fall 360 degree rotation the paddle enters and exits the toner supply. Between the point where the paddle contacts the toner surface and the point where it exits the toner, the toner resists the motion of the paddle and produces a torque load on the paddle shaft. Low toner is detected by either 1) detecting if the torque load caused by the presence of toner is below a given threshold at a fixed paddle location or 2) detecting if the surface of the toner is below a fixed height.
In either method there is a driving member supplying drive torque to a driven member (the paddle) which experiences a load torque when contacting the toner. Some degree of freedom exists for these two members to rotate independently of each other in a carefully defined manner. For the first method 1) above, with no load applied to the paddle, both members rotate together. However, when loaded the paddle lags the driving member by an angular distance that increases with increasing load. In the second method 2), the unloaded paddle leads the rotation of the driving member, under the force of a spring or gravity. When loaded (i.e., the paddle contacts the surface of the toner), the driving and driven members come back into alignment and rotate together. By measuring the relative rotational displacement of the driving and driven members (a.k.a. phase difference) at an appropriate place in the paddle's rotation, the presence of toner can be sensed.
In the prior art, this relative displacement is sensed by measuring the phase difference of two disks. The first disk is rigidly attached to a shaft that provides the driving torque for the paddle. The second disk is rigidly attached to the shaft of the paddle and in proximity to the first disk. Usually both disks have matching notches or slots in them. The alignment of the slots or notches, that is how much they overlap, indicates the phase relationship of the disks and therefore the phase of the driving and driven members.
Various art showing the above methods and variations are set forth below.
In U.S. Pat. No. 4,003,258, issued on Jan. 18, 1977 to Ricoh Co., is disclosed the use of two disks to measure toner paddle location relative to the paddle drive shaft. When the paddle reaches the top of its rotation the coupling between paddle and drive shaft allows the paddle to free fall under the force of gravity until it comes to rest on the toner surface or at the bottom of its rotation. Toner low is detected if the angle through which the paddle falls is greater than a fixed amount (close to 180 degrees). A spring connects the two disks, but the spring is not used for toner detection. It is used to fling toner from the toner reservoir to the developer.
In U.S. Pat. No. 5,216,462, issued to Oki Electric Co., Jun. 1, 1993, is described a system where a spring connects two disks so that the phase separation of the disks indicates torque load on the paddle. An instability is noted in this type of system. It further describes a system similar to the Patent above where the paddle free falls from its top dead position to the surface of the toner. The position of the paddle is sensed through magnetic coupling to a lever outside of the toner reservoir. This lever activates an optical switch when the paddle is near the bottom of its rotation. A low toner indication results when the time taken for the paddle to fall from top dead center to the bottom of the reservoir, as sensed by the optical switch, is less than a given value.
In U.S. Pat. No. 4,592,642, issued on Jun. 3, 1986 to Minolta Camera Co., is described a system that does not use the paddle directly to measure toner, but instead uses the motion of the paddle to lift a "float" above the surface of the toner and drop it back down on top of the toner surface. A switch is activated by the "float" when in the low toner position. If the "float" spends a substantial amount of time in the low toner position the device signals low toner. Although the patent implies that the amount of toner in the reservoir can be measured, the description indicates that it behaves in a very non-linear, almost binary way to merely detect a toner low state.
U.S. Pat. No. 4,989,754, issued on Feb. 5, 1991 to Xerox Corp., differs from the others in that there is no internal paddle to agitate or deliver toner. Instead the whole toner reservoir rotates about a horizontal axis. As the toner inside rotates with the reservoir it drags a rotatable lever along with it. When the toner level becomes low, the lever, no longer displaced from its home position by the movement of the toner, returns to its home position under the force of gravity. From this position the lever activates a switch to indicate low toner.
In still another U.S. Pat. No. 4,711,561, issued on Dec. 8, 1987 to Rank Xerox Limited, this patent describes a means of detecting when a waste toner tank is full. It employs a float that gets pushed upward by waste toner fed into the tank from the bottom. The float activates a switch when it reaches the top of the tank.
U.S. Pat. No. 5,036,363, issued on Jul. 30, 1991 to Fujitsu Limited, describes the use of a commercially available vibration sensor to detect the presence of toner at a fixed level. The patent describes a simple timing method for ignoring the effect of the sensor cleaning mechanism on the sensor output.
U.S. Pat. No. 5,349,377, issued on Sep. 20, 1994 to Xerox Corp. discloses an algorithm for calculating toner usage and hence amount of toner remaining in the reservoir by counting black pixels and weighting them for toner usage based on pixels per unit area in the pixel's neighborhood. This is unlike the inventive method and apparatus disclosed hereinafter.

Method for determining characteristics of an electrophotographic cartridge carrying a rotatable element


An apparatus and method is presented for treating patients with sinus node dysfunction who have apparently normal intrinsic AV conduction and thus do not require ventricular pacing unless there is an unexpected AV conduction failure. In one embodiment, a cardiac device with dual-chamber pacing capability is programmed to operate in a primary DDI (or DDI(R)) mode adjusted to pace only the atria if intrinsic AV conduction is intact and switch to a secondary DDD (or DDD(R)) mode upon detection of AV block.

Cardiac rhythm management devices, which include pacemakers and implantable cardioverer/defibrillators (ICD), are implantable devices that provide electrical stimulation to selected chambers of the heart in order to treat disorders of cardiac rhythm. A pacemaker, for example, is a cardiac rhythm management device that paces the heart with timed pacing pulses. The most common condition for which pacemakers are used is in the treatment of bradycardia, where the ventricular rate is too slow. Atrio-ventricular conduction defects (i.e., AV block) that are permanent or intermittent and sick sinus syndrome represent the most common causes of bradycardia for which permanent pacing may be indicated. If functioning properly, the pacemaker makes up for the heart's inability to pace itself at an appropriate rhythm in order to meet metabolic demand by enforcing a minimum heart rate and/or artificially restoring AV conduction.
Patients with sinus node dysfunction who are unable to maintain an adequate atrial rate (i.e., are chronotropically incompetent) but have intact intrinsic AV conduction are most appropriately treated with atrial pacing only such as AAI mode. (See the pacing modes section below for an explanation of the three-letter code for defining pacing modes.) Although ventricular pacing could also be delivered to these patients, it is preferable from a hemodynamic standpoint to utilize the native AV conduction system for stimulating the ventricles so that optimum atrio-ventricular synchrony is maintained. Also, several major clinical studies have demonstrated that unnecessary ventricular pacing is associated with a significantly increased risk of heart failure and atrial fibrillation in patients with dual-chamber pacemakers and ICDs.
Many patients with sinus node dysfunction, however, are at a higher risk than normal of developing another conduction system disorder such as some degree AV block. In AV block, the conduction of excitation from the atria to the ventricles is either slowed for blocked completely, resulting in atrioventricular dyssynchrony. Most physicians are therefore reluctant to program a pacemaker to AAI mode in patients with sinus node dysfunction because of the risk that they may at some time develop an AV block and need ventricular pacing. One way around this is to program the pacemaker with a dual-chamber mode which paces the atria and then the ventricles after a programmed AV delay interval (e.g., DDD mode) and specify a very long AV delay interval so that the ventricles are never paced as long as intrinsic AV conduction is intact. Such a mode, however, due to the length of the AV delay interval and its associated sensing refractory periods, may cause unacceptable loss of atrial and ventricular sensing capability which interferes with tachyarrhythmia detection. The programmed long AV delay interval also results in long nonphysiological AV delays causing atrioventricular dyssynchrony when ventricular pacing is required, which is clinically detrimental if it occurs for prolonged periods (referred to a pacemaker syndrome).