Showing papers by "University of California published in 1995"

Homological Algebra of Mirror Symmetry

Abstract: Mirror symmetry (MS) was discovered several years ago in string theory as a duality between families of 3-dimensional Calabi-Yau manifolds (more precisely, complex algebraic manifolds possessing holomorphic volume elements without zeros). The name comes from the symmetry among Hodge numbers. For dual Calabi-Yau manifolds V, W of dimension n (not necessarily equal to 3) one has $$\dim {H^p}(V,{\Omega ^q}) = \dim {H^{n - p}}(W,{\Omega ^q}).$$ .

Transaction Cost Economics

Abstract: Torganization by selectively joinin gl aw, economics, and organization theory. As against neoclassical economics, which is predominantly concerned with price and output, relies extensively on marginal analysis, an dd escribes the firm as a production function (whic hi s a technological construction), transaction cost economics (TCE) is concerned with the allocation of economic activity across alternative modes of organization (markets, firms, bureaus, etc.), employs discrete structural analysis, an dd escribes the firm as a governance structure (which is an organizational construction). Real differences notwithstanding, orthodoxy and TCE are in many ways complements—one being more wellsuited to aggregation in the context of simple market exchange, the other being more well-suited to the microanalytics of complex contracting and nonmarket organization. Ib egin by contrasting the lens of contract (out of which TCE works) with the lens of choice (orthodoxy). Vertical integration, which is the paradigm problem for TCE, i st hen examined .T he operationalization of TCE is discusse di n Section 3. Variations on a theme are sketched in Section 4. Public policy is discussed in Section 5. Concluding remarks follow.

An Introduction to the Bootstrap.

Abstract: Introduction The Accuracy of a Sample Mean Random Samples and Probabilities The Empirical Distribution Function and the Plug-In Principle Standard Errors and Estimated Standard Errors The Bootstrap Estimate of Standard Error Bootstrap Standard Errors: Some Examples More Complicated Data Structures Regression Models Estimates of Bias The Jackknife Confidence Intervals Based on Bootstrap "Tables" Confidence Intervals Based on Bootstrap Percentiles Better Bootstrap Confidence Intervals Permutation Tests Hypothesis Testing with the Bootstrap Cross-Validation and Other Estimates of Prediction Error Adaptive Estimation and Calibration Assessing the Error in Bootstrap Estimates A Geometrical Representation for the Bootstrap and Jackknife An Overview of Nonparametric and Parametric Inference Further Topics in Bootstrap Confidence Intervals Efficient Bootstrap Computations Approximate Likelihoods Bootstrap Bioequivalence Discussion and Further Topics Appendix: Software for Bootstrap Computations References

Machine dynamic selection of one video camera/image of a scene from multiple video cameras/images of the scene in accordance with a particular perspective on the scene, an object in the scene, or an event in the scene

Abstract: Each and any viewer of a video or a television scene is his or her own proactive editor of the scene, having the ability to interactively dictate and select--in advance of the unfolding of the scene and by high-level command--a particular perspective by which the scene will be depicted, as and when the scene unfolds. Video images of the scene are selected, or even synthesized, in response no a viewer-selected (i) spatial perspective on the scene, (ii) static or dynamic object appearing in the scene, or (iii) event depicted in the scene. Multiple video cameras, each at a different spatial location, produce multiple two-dimensional video images of the real-world scene, each at a different spatial perspective. Objects of interest in the scene are identified and classified by computer in these two-dimensional images. The two-dimensional images of the scene, and accompanying information, are then combined in the computer into a three-dimensional video database, or model, of the scene. The computer also receives a user/viewer-specified criterion relative to which criterion the user/viewer wishes to view the scene. From the (i) model and (ii) the criterion, the computer produces a particular two-dimensional image of the scene that is in "best" accordance with the user/viewer-specified criterion. This particular two-dimensional image of the scene is then displayed on a video display. From its knowledge of the scene and of the objects and the events therein, the computer may also answer user/viewer-posed questions regarding the scene and its objects and events.

Enumeration of Rational Curves Via Torus Actions

Abstract: This paper contains an attempt to formulate rigorously and to check predictions in enumerative geometry of curves following from Mirror Symmetry.

Immersive video, including video hypermosaicing to generate from multiple video views of a scene a three-dimensional video mosaic from which diverse virtual video scene images are synthesized, including panoramic, scene interactive and stereoscopic images

Abstract: Immersive video, or television, images of a real-world scene are synthesized, including on demand and/or in real time, as are linked to any of a particular perspective on the scene, or an object or event in the scene. Synthesis is in accordance with user-specified parameters of presentation, including presentations that are any of panoramic, magnified, stereoscopic, or possessed of motional parallax. The image synthesis is based on computerized video processing--called "hypermosaicing"--of multiple video perspectives on the scene. In hypermosaicing a knowledge database contains information about the scene; for example scene geometry, shapes and behaviors of objects in the scene, and/or internal and/or external camera calibration models. Multiple video cameras each at a different spatial location produce multiple two-dimensional video images of the scene. A viewer/user specifies viewing criterion (ia) at a viewer interface. A computer, typically one or more engineering work station class computers or better, includes in software and/or hardware (i) a video data analyzer for detecting and for tracking scene objects and their locations, (ii) an environmental model builder combining multiple scene images to build a 3D dynamic model recording scene objects and their instant spatial locations, (iii) a viewer criterion interpreter, and (iv) a visualizer for generating from the 3D model in accordance with the viewing criterion one or more selectively synthesized 2D video image(s) of the scene.

SUMER — Solar Ultraviolet Measurements of Emitted Radiation

Abstract: The instrument SUMER — Solar Ultraviolet Measurements of Emitted Radiation is designed to investigate structures and associated dynamical processes occurring in the solar atmosphere, from the chromosphere through the transition region to the inner corona, over a temperature range from 104 to 2 x 106 K and above. These observations will permit detailed spectroscopic diagnostics of plasma densities and temperatures in many solar features, and will support penetrating studies of underlying physical processes, including plasma flows, turbulence and wave motions, diffusion transport processes, events associated with solar magnetic activity, atmospheric heating, and solar wind acceleration in the inner corona. Specifically, SUMER will measure profiles and intensities of EUV lines; determine Doppler shifts and line broadenings with high accuracy; provide stigmatic images of the Sun in the EUV with high spatial, spectral, and temporal resolution; and obtain monochromatic maps of the full Sun and the inner corona or selected areas thereof. SUMER will be flown on the Solar and Heliospheric Observatory (SOHO), scheduled for launch in November, 1995. This paper has been written to familiarize solar physicists with SUMER and to demonstrate some command procedures for achieving certain scientific observations.

Gender Effects in Pharmacokinetics and Pharmacodynamics

Abstract: There are a number of examples of sex differences in drug pharmacokinetics and pharmacodynamics. Recent advances in the characterisation of specific isozymes involved in drug metabolism now allow for the preliminary identification of enzyme systems that are affected by sex. While current data are somewhat limited and not in complete agreement, the majority of studies show that apparent cytochrome P450 (CYP) 3A4 activity is higher in women than in men, whereas the activity of many other systems involved in drug metabolism may be higher in men than in women. Women and men also show different pharmacodynamic responses to a variety of drugs. While the clinical significance of these sex differences remains to be determined, we anticipate that they will be most important in the administration of drugs that have a narrow therapeutic range. In addition, sex differences in drug metabolism may be involved in the higher incidence of adverse reactions to drugs in women compared with men. Further research is needed to determine the scope and significance of these sex differences. Female-specific issues such as pregnancy, menopause, oral contraceptive use and menstruation may also have profound effects on drug metabolism. These effects can often be clinically important. Pregnancy may increase the elimination of antiepileptic agents, reducing their efficacy. Oral contraceptive use can interfere with the metabolism of many drugs and, conversely, certain drugs can impair contraceptive efficacy. More research is needed to determine the impact of menopause, hormone replacement and menstruation on drug therapy.

Combinatorial synthesis of novel materials

Abstract: Methods and apparatus for the preparation and use of a substrate having an array of diverse materials in predefined regions thereon. A substrate having an array of diverse materials thereon is generally prepared by delivering components of materials to predefined regions on a substrate, and simultaneously reacting the components to form at least two materials. Materials which can be prepared using the methods and apparatus of the present invention include, for example, covalent network solids, ionic solids and molecular solids. More particularly, materials which can be prepared using the methods and apparatus of the present invention include, for example, inorganic materials, intermetallic materials, metal alloys, ceramic materials, organic materials, organometallic materials, non-biological organic polymers, composite materials (e.g., inorganic composites, organic composites, or combinations thereof), etc. Once prepared, these materials can be screened for useful properties including, for example, electrical, thermal, mechanical, morphological, optical, magnetic, chemical, or other properties. Thus, the present invention provides methods for the parallel synthesis and analysis of novel materials having useful properties.

Modified green fluorescent proteins

Abstract: Modifications in the sequence of Aequorea wild-type GFP provide products having markedly different excitation and emission spectra from corresponding products from wild-type GFP. In one class of modifications, the product derived from the modified GFP exhibits an alteration in the ratio of two main excitation peaks observed with the product derived from wild-type GFP. In another class, the product derived from the modified GFP fluoresces at a shorter wavelength than the corresponding product from wild-type GFP. In yet another class of modifications, the product derived from the modified GFP exhibits only a single excitation peak and enhanced emission relative to the product derived from wild-type GFP.

Method and apparatus for thermal therapy of tumors

Abstract: An ultrasound applicator for thermal therapy, having a multi-element array of plastic or rubber coated piezoceramic tubular transducers, each with separate power control and supported by a coaxially disposed semi-flexible central tube, which can be placed directly within the tumor or target region, or within a body lumen such as a blood vessel or body cavity such as the urethra, or within a separate delivery catheter or system. Thermocouple sensors embedded in the coating over each transducer can be used for continuous monitoring of the tissue/applicator interface temperatures for feedback control of the power applied to each transducer. The transducers are resonant across the wall thickness and radiate energy in the radial direction. The applicator provides an air-cooling system which can control the temperature of the transducers and thereby improve heating characteristics. In the primary configuration, the central tube is a catheter which is compatible with remote afterloaders and standard brachytherapy technology, and facilitates the delivery of interstitial thermal therapy in conjunction with simultaneous brachytherapy or radiotherapy from within the applicator. For alternate forms of therapy or when the radiation source is not in the catheter, the central catheter can be used to circulate temperature regulated air or water to control the surface temperature of the applicator, or to infuse drugs. Further, the applicator can be placed within a thin-walled implant catheter and flushed with temperature controlled circulating coupling fluid to control the temperature of the catheter/tissue interface, or used in conjunction with other conventional delivery systems, instead of being used interstitially.

The Coronal Diagnostic Spectrometer for the solar and heliospheric observatory

Abstract: The Coronal Diagnostic Spectrometer is designed to probe the solar atmosphere through the detection of spectral emission lines in the extreme ultraviolet wavelength range 150–800 A. By observing the intensities of selected lines and line profiles we may derive temperature, density, flow and abundance information for the plasmas in the solar atmosphere. Spatial and temporal resolutions of down to a few arcseconds and seconds, respectively, allow such studies to be made within the fine-scale structure of the solar corona. Furthermore, coverage of large wavelength bands provides the capability for simultaneously observing the properties of plasmas across the wide temperature ranges of the solar atmosphere.

Laser production of articles from powders

Abstract: Method and apparatus for forming articles from materials in particulate form in which the materials are melted by a laser beam and deposited at points along a tool path to form an article of the desired shape and dimensions. Preferably the tool path and other parameters of the deposition process are established using computer-aided design and manufacturing techniques. A controller comprised of a digital computer directs movement of a deposition zone along the tool path and provides control signals to adjust apparatus functions, such as the speed at which a deposition head which delivers the laser beam and powder to the deposition zone moves along the tool path.

Comparative fluorescence hybridization to nucleic acid arrays

Abstract: The present invention provides methods of determining relative copy number of target nucleic acids and precise mapping of chromosomal abnormalities associated with disease. The methods of the invention use target nucleic acids immobilized on a solid surface, to which a sample comprising two sets of differentially labeled nucleic acids are hybridized. The hybridization of the labeled nucleic acids to the solid surface is then detected using standard techniques.

XOR MACs: New Methods for Message Authentication Using Finite Pseudorandom Functions

Abstract: We describe a new approach for authenticating a message using a finite pseudorandom function (PRF). Our "XOR MACs" have several nice features, including parallelisability, incrementality, and provable security. The finite PRF can be "instantiated" via DES (yielding an alternative to the CBC MAC), via the compression function of MD5 (yielding an alternative to various "keyed MD5" constructions), or in a variety of other ways. The proven security is quantitative, expressing the adversary's inability to forge in terms of her (presumed) inability to break the underlying finite PRF. This is backed by attacks showing the analysis is tight. Our proofs exploit linear algebraic techniques.

Method and apparatus for capacitive deionization and electrochemical purification and regeneration of electrodes

Abstract: An electrically regeneratable electrochemical cell (30) for capacitive deionization and electrochemical purification and regeneration of electrodes includes two end plates (31, 32), one at each end of the cell (30). Two end electrodes (35, 36) are arranged one at each end of the cell (30), adjacent to the end plates (31, 32). An insulator layer (33) is interposed between each end plate (31, 32) and the adjacent end electrode (35, 36). Each end electrode (35, 36) includes a single sheet (44) of conductive material having a high specific surface area and sorption capacity. In one embodiment, the sheet (44) of conductive material is formed of carbon aerogel composite. The cell (30) further includes a plurality of generally identical double-sided intermediate electrodes (37-43) that are equidistally separated from each other, between the two end electrodes (35, 36). As the electrolyte enters the cell, it flows through a continuous open serpentine channel (65-71) defined by the electrodes, substantially parallel to the surfaces of the electrodes. By polarizing the cell (30), ions are removed from the electrolyte and are held in the electric double layers formed at the carbon aerogel surfaces of the electrodes. As the cell (30) is saturated with the removed ions, the cell (30) is regenerated electrically, thus significantly minimizing secondary wastes.

The ligands and receptors of the lymphotoxin system.

Abstract: The tumor necrosis factor (TNF)-related cytokines have emerged over the past 2 years as a large family of pleiotropic mediators of host defense and immune regulation. Members of this family exist in membrane-anchored forms acting locally through cell-to-cell contact, or as secreted proteins capable diffusion to more distant targets. A parallel family of receptors signals the presence of these molecules leading to the initiation of cell death or cellular proliferation and differentiation in the target tissue (see Smith et al. 1994; Banchereau et al. 1994 for reviews). The focus of this review is on two members of this family produced by activated T cells, the original lymphotoxin-α (LT-α, previously referred to as TNF-β), and a new member, lymphotoxin-β (LT-β), and their specific receptors. Initially discovered by cytotoxic activity in vitro, lymphotoxn, as a secreted molecule, was one of the earliest postulated mechanisms used by cytotoxic T lymphocytes (Ruddle and Waksman 1968; Granger and Williams 1868). The molecular cloning of LT and TNF dramatically revised the view of these cytokines as limited nonspecific cytotoxins and revealed their more intricate role in immunoregulation and host defense. Although once thought to be merely a redundant form of TNF, new findings have indicated that lymphotoxin has a role in immune physiology distinct from TNF and forms a system of secreted and membrane-anchored immunoregulatory molecules.

Interleukin 4 production by CD4+ T cells from allergic individuals is modulated by antigen concentration and antigen-presenting cell type.

Abstract: We have previously shown that CD4+ T cells from allergic individuals are predisposed to produce interleukin (IL)-4 in response to allergens, and that allergen immunotherapy greatly reduced IL-4 production in an allergen-specific fashion. The mechanism that results in the reduction of IL-4 synthesis in treated individuals is unknown, but because clinical improvement during immunotherapy is associated with the administration of the highest doses of allergen, we hypothesized that high concentration of allergen results in the downregulation of IL-4 synthesis in CD4+ T cells. In this report, we demonstrated that CD4+ T cells from allergic donors produced high levels of IL-4 when stimulated with low concentrations of allergen (0.003-0.01 micrograms/ml), particularly when B cell-enriched populations presented the antigen. In contrast, the same responding CD4+ T cell population produced little IL-4 when stimulated with high concentrations of allergen (10-30 micrograms/ml), especially when monocytes were used as antigen-presenting cells (APC). The quantity of IL-4 produced was also found to be inversely related to the extent of proliferation of the CD4+ T cells in response to allergen/antigen; maximal proliferation of CD4+ T cells occurred in response to high concentrations of antigen when IL-4 production was minimal. Antigen presentation by B cell-enriched populations, instead of monocytes, induced less CD4+ T cell proliferation, but induced much greater IL-4 synthesis. Moreover, the addition of increasing numbers of APC (either B cells or monocytes) to cultures containing a constant number of responder T cells resulted in increased T cell proliferation and decreased IL-4 production. These results indicate that the circumstances under which memory T cells are activated, as well as the strength of the proliferative signal to T cells, greatly affect the quantity of IL-4 produced. Thus, our observations that the cytokine profile of allergen-specific memory CD4+ T cells can indeed be modulated by the antigen dose and APC type suggest that methods that preferentially enhance allergen uptake by monocytes and that enhance T cell proliferation will improve the clinical efficacy of immunotherapy in the treatment of allergic disease.

The Ultraviolet Coronagraph Spectrometer for the Solar and Heliospheric Observatory

Abstract: The SOHO Ultraviolet Coronagraph Spectrometer (UVCS/SOHO) is composed of three reflecting telescopes with external and internal occultation and a spectrometer assembly consisting of two toric grating spectrometers and a visible light polarimeter. The purpose of the UVCS instrument is to provide a body of data that can be used to address a broad range of scientific questions regarding the nature of the solar corona and the generation of the solar wind. The primary scientific goals are the following: to locate and characterize the coronal source regions of the solar wind, to identify and understand the dominant physical processes that accelerate the solar wind, to understand how the coronal plasma is heated in solar wind acceleration regions, and to increase the knowledge of coronal phenomena that control the physical properties of the solar wind as determined by in situ measurements. To progress toward these goals, the UVCS will perform ultraviolet spectroscopy and visible polarimetry to be combined with plasma diagnostic analysis techniques to provide detailed empirical descriptions of the extended solar corona from the coronal base to a heliocentric height of 12 solar radii.

Etchants for use in micromachining of CMOS Microaccelerometers and microelectromechanical devices and method of making the same

Abstract: What is described in the present specification are accelerometers using tiny proof masses and piezoresistive force detection. Conventional wisdom would indicate that this approach would not yield useful sensors. However, in fact, according to the invention, such devices are suitable in a wide range of applications. The devices may include deformable hinges to allow the fabrication of three dimensional structures. A new system has been developed which etches silicon highly selectively at moderate temperatures and without hydrodynamic forces potentially damaging to small structures and features. The system is based on the use of the gas phase etchant xenon diflouride, which is an unremarkable white solid at standard temperature and pressure.

Apparatus and method for dynamic cooling of biological tissues for thermal mediated surgery

Abstract: Dynamically cooling the epidermis of a port wine stain patient undergoing laser therapy permits maximization of the thermal damage to the port wine stain while at the same time minimizing nonspecific injury to the normal overlying epidermis. A cryogenic spurt is applied to the skin surface for a predetermined short period of time in the order of tens of milliseconds so that the cooling remains localized in epidermis while leaving the temperature of deeper port wine stain vessels substantially unchanged. The result is that epidermal denaturation and necrosis which normally occurs in uncooled laser irradiated skin sites does not occur and that clinically significant blanching of the port wine stains at the dynamically cooled sites establishes that selective laser photothermolysis of the port wine stain blood vessels is achieved. In addition, dynamic epidermal cooling reduces patient discomfort normally associated with flashlamp-pumped pulsed dye laser therapy.

Compact Intermediate States in Protein Folding

Abstract: Recently there has been growing recognition of the existence and importance of compact intermediate states of proteins. Such species have been observed under both transient (refolding kinetics) and equilibrium conditions. It is clear that for many proteins most denaturing conditions do not lead to a fully unfolded protein (random coil), but rather to species with substantial secondary structure and substantial compactness, relative to the fully unfolded state. In addition, there is now good experimental data to demonstrate the existence of two classes of compact denatured states of proteins: compact intermediates, in the thermodynamic sense (i.e., a minimum in the free energy profile for the reaction), and compact substates of the unfolded state (Palleros et al., 1993). It is important to note that it is often experimentally difficult to distinguish between these two types of compact denatured states, especially by spectral methods. Recent reviews of compact denatured states, and particularly the molten globule, include those of Dill and Shortle (1991), Ptitsyn (1987, 1992), Kuwajima (1989), Christensen and Pain (1991), and Baldwin and Roder (1991). Theoretical models for the existence of two classes of denatured states have been presented by Dill and co-workers (Alonso et al., 1991), Ptitsyn (1987, 1992), and Finkelstein and Shakhnovich (1989).

Apparatus for fabricating self-assembling microstructures

Abstract: Apparatus for assembling microstructures onto a substrate through fluid transport. The apparatus includes a vessel that contains the substrate, a fluid, and microstructures. The substrate has at least one recessed region thereon. The microstructures being shaped blocks self-align into the recessed regions located on the substrate such that the microstructure becomes integral with the substrate. The apparatus also includes a pump that circulates the microstructures within the vessel at a rate where at least one of the microstructures is disposed into the recessed region.

It Usually Works: The Temporal Logic of Stochastic Systems

Abstract: In this paper the branching time logic pCTL* is defined pCTL* expresses quantitative bounds on the probabilities of correct behavior; it can be interpreted over discrete Markov processes A bisimulation relation is defined on finite Markov processes, and shown to be sound and complete with respect to pCTL* We extend the universe of models to generalized Markov processes in order to support notions of refinement, abstraction, and parametrization Model checking pCTL* over generalized Markov processes is shown to be elementary by a reduction to RCF We conclude by describing practical and theoretical avenues for further work

Quantitative DNA fiber mapping

Abstract: The present invention relates generally to the DNA mapping and sequencing technologies. In particular, the present invention provides enhanced methods and compositions for the physical mapping and positional cloning of genomic DNA. The present invention also provides a useful analytical technique to directly map cloned DNA sequences onto individual stretched DNA molecules.

Methods and devices for immunizing a host to tumor-associated antigens through administration of naked polynucleotides which encode tumor-associated antigenic peptides

Abstract: The invention is directed to methods for introducing biologically active peptides into a host administration of polynucleotides which operatively encode for the peptide of interest. In a preferred embodiment of the invention, a host who has been identified as having a tumor bearing at least one tumor-associated antigen is the recipient of a polynucleotide which operatively encodes for a foreign mimic of the tumor-associated antigen or a mutation of the self-antigen. The antigen-encoding polynucleotides are administered to host tissues which have a high concentration of antigen presenting cells in them relative to other host tissues. The method is particularly useful in treating cancer through induction of antigen-specific cytotoxic T lymphocytes in the host for lysis of tumor cells bearing the antigen. Devices and compositions for use in the methods of the invention are also described.

Fate and effects of acrolein.

Abstract: Acrolein, an α,β-unsaturated aldehyde, is a highly reactive, irritating chemical derived from a variety of sources. It occurs as a product of organic pyrolysis, a metabolite of various compounds, a reaction intermediate, a contaminant in some foods and drinks, and a residue in water when used for the control of aquatic plants, algae, bacteria, and mollusks (Izard and Libermann 1978). Valued for its lacrimatory and vesicant properties, it was used by the French during World War I as the warfare agent “papite.” Highly flammable, and with a pungent, choking, disagreeable odor, acrolein is capable of spontaneous polymerization, and therefore it can be difficult to handle.

Probes labelled with energy transfer coupled dyes

Abstract: Compositions are provided comprising sets of fluorescent labels carrying pairs of donor and acceptor dye molecules, designed for efficient excitation of the donors at a single wavelength and emission from the acceptor in each of the pairs at different wavelengths. The different molecules having different donor-acceptor pairs can be modified to have substantially the same mobility under separation conditions, by varying the distance between the donor and acceptor in a given pair. Particularly, the fluorescent compositions find use as labels in sequencing nucleic acids.

Ergodic Theory of Differentiable Dynamical Systems

Abstract: These notes are about the dynamics of systems with hyperbolic properties. The setting for the first half consists of a pair (f, µ), where f is a diffeomorphism of a Riemannian manifold and µ is an f-invariant Borel probability measure. After a brief review of abstract ergodic theory, Lyapunov exponents are introduced, and families of stable and unstable manifolds are constructed. Some relations between metric entropy, Lyapunov exponents and Hausdorff dimension are discussed. In the second half we address the following question: given a differentiable mapping, what are its natural invariant measures? We examine the relationship between the expanding properties of a map and its invariant measures in the Lebesgue measure class. These ideas are then applied to the construction of Sinai-Ruelle-Bowen measures for Axiom A attractors. The nonuniform case is discussed briefly, but its details are beyond the scope of these notes.