cssi/SciSciGPT-SciSciNet huggingface dataset:
Experimental demonstration of particle acceleration with normal conducting accelerating structure at cryogenic temperature

In this paper, we present an experimental demonstration of the high-gradient operation of an X-band, 11.424 GHz, 20-cells linear accelerator (linac) operating at a liquid nitrogen temperature of 77 K. The tested linac was previously processed and tested at room temperature. Low-temperature operation increases the yield strength of the accelerator material and reduces surface resistance, hence a great reduction in cyclic fatigue could be achieved resulting in a large reduction in breakdown rates compared to room-temperature operation. Furthermore, temperature reduction increases the intrinsic quality factor of the accelerating cavities, and consequently, the shunt impedance leading to increased rf-to-beam efficiency and beam loading capabilities. We verified the enhanced accelerating parameters of the tested accelerator at cryogenic temperature using different measurements including electron beam acceleration up to a gradient of $150\text{ }\text{ }\mathrm{MV}/\mathrm{m}$, corresponding to a peak surface electric field of $375\text{ }\text{ }\mathrm{MV}/\mathrm{m}$. We also measured the breakdown rates in the tested structure showing a reduction of 2 orders of magnitude compared to their values at room temperature for the same accelerating gradient.
Vasconcelos’ conjecture on the conormal module

For any ideal I of finite projective dimension in a commutative noetherian local ring R, we prove that if the conormal module $$I/I^2$$ has finite projective dimension over R/I, then I must be generated by a regular sequence. This resolves a conjecture of Vasconcelos. We prove a similar result for the first Koszul homology module of I. When R is a localisation of a polynomial ring over a field K of characteristic zero, Vasconcelos conjectured that R/I is a reduced complete intersection if the module $$\Omega _{(R/I)/K}$$ of Kahler differentials has finite projective dimension; we prove this contingent on the Eisenbud-Mazur conjecture. The arguments exploit the structure of the homotopy Lie algebra associated to I in an essential way. By work of Avramov and Halperin, if every degree 2 element of the homotopy Lie algebra is radical, then I is generated by a regular sequence. Iyengar has shown that free summands of $$I/I^2$$ give rise to central elements of the homotopy Lie algebra, and we establish an analogous criterion for constructing radical elements, from which we deduce our main result.
Learning to control active matter

The study of active matter has revealed novel non-equilibrium collective behaviors, illustrating their potential as a new materials platform. However, most work treat active matter as unregulated systems with uniform microscopic energy input, which we refer to as activity. In contrast, functionality in biological materials results from regulating and controlling activity locally over space and time, as has only recently become experimentally possible for engineered active matter. Designing functionality requires navigation of the high-dimensional space of spatio-temporal activity patterns, but brute force approaches are unlikely to be successful without system-specific intuition. Here, we apply reinforcement learning to the task of inducing net transport in a specific direction for a simulated system of Vicsek-like self-propelled disks using a spotlight that increases activity locally. The resulting time-varying patterns of activity learned exploit the distinct physics of the strong and weak coupling regimes. Our work shows how reinforcement learning can reveal physically interpretable protocols for controlling collective behavior in non-equilibrium systems.
Field Convolutions for Surface CNNs

We present a novel surface convolution operator acting on vector fields that is based on a simple observation: instead of combining neighboring features with respect to a single coordinate parameterization defined at a given point, we have every neighbor describe the position of the point within its own coordinate frame. This formulation combines intrinsic spatial convolution with parallel transport in a scattering operation while placing no constraints on the filters themselves, providing a definition of convolution that commutes with the action of isometries, has increased descriptive potential, and is robust to noise and other nuisance factors. The result is a rich notion of convolution which we call field convolution, well-suited for CNNs on surfaces. Field convolutions are flexible and straight-forward to implement, and their highly discriminating nature has cascading effects throughout the learning pipeline. Using simple networks constructed from residual field convolution blocks, we achieve state-of-the-art results on standard benchmarks in fundamental geometry processing tasks, such as shape classification, segmentation, correspondence, and sparse matching.
Repair of Progressive Retinal Detachment Complicating Degenerative Retinoschisis: Surgical Management and Outcomes in Phakic Eyes

BACKGROUND Degenerative retinoschisis is a common condition defined by the splitting of the neurosensory retina that may rarely be associated with progressive retinal detachment (RD). Here, we aim to describe the anatomic and functional outcomes of surgical treatment of progressive symptomatic retinal detachment complicating degenerative retinoschisis (PSRDCR) using pars plana vitrectomy (PPV), scleral buckle (SB), or combined PPV/SB procedure. METHODS A retrospective chart review of patients with PSRDCR between Jan 1, 2008 and Dec 31, 2019 was conducted. Data regarding demographics, surgical approach, and anatomic/functional outcomes were collected. RESULTS Of the 4973 charts with RD repair during the study period, 36 eyes (0.7%) had retinoschisis with RD. 18 eyes met inclusion criteria (0.4%). The median age was 54 years (range 18-74) and all eyes were phakic. All eyes had outer layer breaks (OLBs) and 16 eyes (89%) had identifiable inner layer breaks. All OLBs were posterior to the equator in charts where position was recorded (16 eyes). The single surgery anatomic success (SSAS) and final anatomical success rates were 66% (12/18) and 100%, respectively. Eyes treated with PPV/SB had an SSAS rate of 75% (9/12), while PPV and SB had SSAS rates of 66% (2/3) and 33% (1/3), respectively. CONCLUSIONS PSRDCR is an exceedingly rare complication of degenerative retinoschisis associated with an SSAS rate lower than for uncomplicated rhegmatogenous RD. The majority of PSRDCR were repaired via combined PPV/SB in our study, and the rarity of this complication limits statistical support of an optimal surgical method in our and prior studies. The role of SB combined with PPV for PSRDCR requires further investigation.
Baking Neural Radiance Fields for Real-Time View Synthesis

Neural volumetric representations such as Neural Radiance Fields (NeRF) have emerged as a compelling technique for learning to represent 3D scenes from images with the goal of rendering photorealistic images of the scene from unobserved viewpoints. However, NeRF's computational requirements are prohibitive for real-time applications: rendering views from a trained NeRF requires querying a multilayer perceptron (MLP) hundreds of times per ray. We present a method to train a NeRF, then precompute and store (i.e. "bake") it as a novel representation called a Sparse Neural Radiance Grid (SNeRG) that enables real-time rendering on commodity hardware. To achieve this, we introduce 1) a reformulation of NeRF's architecture, and 2) a sparse voxel grid representation with learned feature vectors. The resulting scene representation retains NeRF's ability to render fine geometric details and view-dependent appearance, is compact (averaging less than 90 MB per scene), and can be rendered in real-time (higher than 30 frames per second on a laptop GPU). Actual screen captures are shown in our video.
A Computational Geometry Approach for Modeling Neuronal Fiber Pathways.

We propose a novel and efficient algorithm to model high-level topological structures of neuronal fibers. Tractography constructs complex neuronal fibers in three dimensions that exhibit the geometry of white matter pathways in the brain. However, most tractography analysis methods are time consuming and intractable. We develop a computational geometry-based tractography representation that aims to simplify the connectivity of white matter fibers. Given the trajectories of neuronal fiber pathways, we model the evolution of trajectories that encodes geometrically significant events and calculate their point correspondence in the 3D brain space. Trajectory inter-distance is used as a parameter to control the granularity of the model that allows local or global representation of the tractogram. Using diffusion MRI data from Alzheimer’s patient study, we extract tractography features from our model for distinguishing the Alzheimer’s subject from the normal control. Software implementation of our algorithm is available on GitHub (https://github.com/UCSB-VRL/ReebGraph).
Enabling Sustainable Clouds: The Case for Virtualizing the Energy System

Cloud platforms' growing energy demand and carbon emissions are raising concern about their environmental sustainability. The current approach to enabling sustainable clouds focuses on improving energy-efficiency and purchasing carbon offsets. These approaches have limits: many cloud data centers already operate near peak efficiency, and carbon offsets cannot scale to near zero carbon where there is little carbon left to offset. Instead, enabling sustainable clouds will require applications to adapt to when and where unreliable low-carbon energy is available. Applications cannot do this today because their energy use and carbon emissions are not visible to them, as the energy system provides the rigid abstraction of a continuous, reliable energy supply. This vision paper instead advocates for a "carbon first" approach to cloud design that elevates carbon-efficiency to a firs--class metric. To do so, we argue that cloud platforms should virtualize the energy system by exposing visibility into, and software-defined control of, it to applications, enabling them to define their own abstractions for managing energy and carbon emissions based on their own requirements.
Getting a handle on the Conway knot

A knot is said to be slice if it bounds a smooth disk in the 4-ball. For 50 years, it was unknown whether a certain 11 crossing knot, called the Conway knot, was slice or not, and until recently, this was the only one of the thousands of knots with fewer than 13 crossings whose slice-status remained a mystery. We will describe Lisa Piccirillo's proof that the Conway knot is not slice. The main idea of her proof is given in the title of this article.
Calcium waves facilitate and coordinate the contraction of endfeet actin stress fibers in Drosophila interommatidial cells.

Actomyosin contraction shapes the Drosophila eye's panoramic view. The convex curvature of the retinal epithelium, organized in ∼800 close-packed ommatidia, depends upon a fourfold condensation of the retinal floor mediated by contraction of actin stress fibers in the endfeet of interommatidial cells (IOCs). How these tensile forces are coordinated is not known. Here, we discover a novel phenomenon: Ca2+ waves regularly propagate across the IOC network in pupal and adult eyes. Genetic evidence demonstrates that IOC waves are independent of phototransduction, but require inositol 1,4,5-triphosphate receptor (IP3R), suggesting these waves are mediated by Ca2+ releases from ER stores. Removal of IP3R disrupts stress fibers in IOC endfeet and increases the basal retinal surface by ∼40%, linking IOC waves to facilitating stress fiber contraction and floor morphogenesis. Further, IP3R loss disrupts the organization of a collagen IV network underneath the IOC endfeet, implicating ECM and its interaction with stress fibers in eye morphogenesis. We propose that coordinated cytosolic Ca2+ increases in IOC waves promote stress fiber contractions, ensuring an organized application of the planar tensile forces that condense the retinal floor.
Neural bases of risky decisions involving nicotine vapor versus monetary reward.

Abstract Substantial effort has gone into neuroimaging studies of neural mechanisms underlying addiction. Human studies of smoking typically either give monetary reward during an fMRI task or else allow subjects to smoke outside the scanner, after the session. This raises a fundamental issue of construct validity, as it is unclear whether the same neural mechanisms process decisions about nicotine that process decisions about money. To address this, we developed a novel MR-compatible nicotine vaping device, such that access to nicotine vapor could be controlled and monitored. We recruited heavy smokers (Money: 45 subjects, 13 females and 32 males; Nicotine: 21 subjects, 4 females and 17 males) to perform a gambling task with nicotine and monetary reward on separate days. We collected BOLD fMRI data while they performed the task inside the scanner and analyzed it using general linear modeling, with inference based on cluster-size correction. This allowed a direct comparison between the neural mechanisms of choosing and receiving immediate drug vs. monetary reward. We found substantial differences in the neural mechanisms that underlie risky choices about money vs. drug reward, including a reversal of the well-known error effects in the medial prefrontal cortex.
High-Dimensional Mediation Analysis with Applications to Causal Gene Identification

Mediation analysis has been a popular framework for elucidating the mediating mechanism of the exposure effect on the outcome in many disciplines including genetic studies. Previous literature in causal mediation primarily focused on the classical settings with univariate exposure and univariate mediator, with recent growing interests in high-dimensional mediator. In this paper, we study the mediation model with high-dimensional exposure, high-dimensional continuous mediator, and a continuous outcome. We introduce two procedures for mediator selection, MedFix and MedMix, and develop the corresponding causal effect tests. Our study is motivated by the causal gene identification problem in biomedical studies, where causal genes are defined as the genes that mediate the genetic effect. For this problem, the genetic variants are the high-dimensional exposure, the gene expressions the high-dimensional mediator, and the phenotype of interest the outcome. We evaluate the proposed methods using a mouse f2 dataset for diabetes study, and extensive real data-driven simulations. We show that the mixed model-based approach (MedMix) leads to higher accuracy in mediator selection with reasonable reproducibility across independent measurements of the response and is more robust against model misspecification. The R code and additional materials are available on Github ( https://github.com/QiZhangStat/highMed ).
A First-Order Optimization Algorithm for Statistical Learning with Hierarchical Sparsity Structure

In many statistical learning problems, it is desired that the optimal solution conform to an a priori known sparsity structure represented by a directed acyclic graph. Inducing such structures by m...
Scalable Mitigation of Measurement Errors on Quantum Computers

A new quantum error mitigation method outputs results within a few seconds for a sizable system--a feat that would otherwise be impractical.
Automatic Head Overcoat Thickness Measure with NASNet-Large-Decoder Net

Transmission electron microscopy (TEM) is one of the primary tools to show microstructural characterization of materials as well as film thickness. However, manual determination of film thickness from TEM images is time-consuming as well as subjective, especially when the films in question are very thin and the need for measurement precision is very high. Such is the case for head overcoat (HOC) thickness measurements in the magnetic hard disk drive industry. It is therefore necessary to develop software to automatically measure HOC thickness. In this paper, for the first time, we propose a HOC layer segmentation method using NASNet-Large as an encoder and then followed by a decoder architecture, which is one of the most commonly used architectures in deep learning for image segmentation. To further improve segmentation results, we are the first to propose a post-processing layer to remove irrelevant portions in the segmentation result. To measure the thickness of the segmented HOC layer, we propose a regressive convolutional neural network (RCNN) model as well as orthogonal thickness calculation methods. Experimental results demonstrate a higher dice score for our model which has lower mean squared error and outperforms current state-of-the-art manual measurement.
Multiple stages of evolutionary change in anthrax toxin receptor expression in humans

The advent of animal husbandry and hunting increased human exposure to zoonotic pathogens. To understand how a zoonotic disease may have influenced human evolution, we study changes in human expression of anthrax toxin receptor 2 (ANTXR2), which encodes a cell surface protein necessary for Bacillus anthracis virulence toxins to cause anthrax disease. In immune cells, ANTXR2 is 8-fold down-regulated in all available human samples compared to non-human primates, indicating regulatory changes early in the evolution of modern humans. We also observe multiple genetic signatures consistent with recent positive selection driving a European-specific decrease in ANTXR2 expression in multiple tissues affected by anthrax toxins. Our observations fit a model in which humans adapted to anthrax disease following early ecological changes associated with hunting and scavenging, as well as a second period of adaptation after the rise of modern agriculture.
Intertemporal Content Variation with Customer Learning

Problem definition: We analyze a firm that sells repeatedly to a customer population over multiple periods. Although this setting has been studied extensively in the context of dynamic pricing—sell...
Dopamine D1 and D4 receptors contribute to light adaptation in ON-sustained retinal ganglion cells.

The adaptation of ganglion cells to increasing light levels is a crucial property of the retina. The retina must respond to light intensities that vary by 10-12 orders of magnitude, but the dynamic range of ganglion cell responses covers only ~3 orders of magnitude. Dopamine is a crucial neuromodulator for light adaptation and activates receptors in the D1 and D2 families. D1Rs are expressed on horizontal cells and some bipolar, amacrine and ganglion cells. In the D2 family D2Rs are expressed on dopaminergic amacrine cells and D4Rs are primarily expressed on photoreceptors. However, the roles of activating these receptors to modulate the synaptic properties of the inputs to ganglion cells are not yet clear. Here we used single cell retinal patch-clamp recordings from the mouse retina to determine how activating D1Rs and D4Rs changed the light-evoked and spontaneous excitatory inputs to ON-sustained (ON-s) ganglion cells. We found that both D1R and D4R activation decrease the light-evoked excitatory inputs to ON-s ganglion cells, but that only the sum of the peak response decrease due to activating the two receptors was similar to the effect of light adaptation to a rod-saturating background. The largest effects on spontaneous excitatory activity of both D1R and D4R agonists was on the frequency of events, suggesting that both D1Rs and D4Rs are acting upstream of the ganglion cells.
Computing the Gysin Map Using Fixed Points

The Gysin map of a map between compact oriented manifolds is the map in cohomology induced by the push-forward map in homology. In enumerative algebraic geometry, formulas for the Gysin map of a flag bundle play a vital role. These formulas are usually proven by algebraic or combinatorial means. This article shows how the localization formula in equivariant cohomology provides a systematic method for calculating the Gysin homomorphism in the ordinary cohomology of a fiber bundle. As examples, we recover classical pushforward formulas for generalized flag bundles. Our method extends the classical formulas to fiber bundles with equivariantly formal fibers.
Re-Examination of Classroom Rules: The Need for Clarity and Specified Behavior

Abstract This article provides a contemplative, research-based discussion of classroom management by examining classroom rules. The introduction contains a discussion establishing the importance of effective classroom management strategies. The article also provides a consideration of the literature to gain a better understanding of ineffective and effective rules.
An instructional module for teaching ethics within an ECE curriculum

Incorporating Electrical and Computer Engineering (ECE) case studies when teaching ethics can help ECE students to relate to the engineering ethics concepts that are taught in the classroom. This paper describes an instructional module that has been used to teach ethics to ECE undergraduates. This module includes ECE case studies, as well as classroom activities that utilize the ethics code of conduct of the following professional bodies: IEEE, IEEE Computer Society, ACM (Association for Computing Machinery), and the NSPE (National Society of Professional Engineers).
Subparabolic, Superparabolic, and Parabolic Functions on a Slab

If \( \dot{D} \) is the slab \( {{\mathbb{R}}^{N}} \times \left] {0,\delta } \right[ \), with \( 0 < \delta + \infty \), the restriction to \( \dot{D} \times \dot{D} \) of \( \dot{G} \) satisfies the rather vague description of the Green function \( {{\dot{G}}_{{\dot{D}}}} \) given in Section XV.7 for smooth regions. It is therefore to be expected from XV(7.3) that the upper boundary of \( \dot{D} \) if \( \delta < + \infty \) is a parabolic measure null set and that parabolic measure on the lower boundary is given by $$ {{\dot{u}}_{{\dot{D}}}}(\dot{\xi },d\eta ) = b(s,\xi - \eta ){{l}_{N}}(d\eta ) = \dot{G}(\dot{\xi },(\eta ,0)){{l}_{N}}(dn)\quad \left[ {\dot{\xi } = (\xi ,s)} \right], $$ so that if \( \dot{u} \) is parabolic on \( \dot{D} \) with boundary function f in some suitable sense on the lower boundary and if \( \dot{u} \) is appropriately restricted, then $$ \dot{u}(\dot{\xi }) = \int_{{{{\mathbb{R}}^{N}}}} {b(s,\xi - \eta )f(\eta ){{l}_{N}}(d\eta )\quad \left[ {\dot{\xi } = (\xi ,s)} \right].} $$ (1)
Micropower logic circuits

Digital logic circuits for space vehicle logic systems for application in nonspace computer systems
Cell probe lower bounds for succinct data structures

In this paper, we consider several static data structure problems in the deterministic cell probe model. We develop a new technique for proving lower bounds for succinct data structures, where the redundancy in the storage can be small compared to the information-theoretic minimum. In fact, we succeed in matching (up to constant factors) the lower order terms of the existing data structures with the lower order terms provided by our lower bound. Using this technique, we obtain (i) the first lower bound for the problem of searching and retrieval of a substring in text; (ii) a cell probe lower bound for the problem of representing permutation π with queries π(i) and π−1(i) that matches the lower order term of the existing data structures, and (iii) a lower bound for representing binary matrices that is also matches upper bounds for some set of parameters. The nature of all these problems is that we are to implement two operations that are in a reciprocal relation to each other (search and retrieval, computing forward and inverse element, operations on rows and columns of a matrix). As far as we know, this paper is the first to provide an insight into such problems.
The Impact of Anomalous Information, Personality, and Motivation on Self- Regulatory Processes in a Multimedia Vicarious Learning Environment.

Regulating one’s learning involves analyzing the learning context, setting and managing meaningful learning goals, determining which learning strategies to use, assessing whether the strategies are effective in meeting the learning goals, evaluating emerging understanding of the topic, and determining whether there are aspects of the learning context which could be used to facilitate learning. The focus of this paper is on one specific self-regulatory process: self-questioning. Self-questioning specifically refers to a self-regulatory process in which a leaner formulates a question, inquiry, or hypothesis about the material being studied. The current study was designed to assess the potential benefits of presenting anomalous information to the learner in order to produce a state of cognitive disequilibrium which in turn could potentially lead to an increase in the quantity and quality of questions. A significant difference in question asking quantity as a function of condition was discovered. Furthermore, certain individual differences were discovered to have an impact on who most benefited from the presentation of anomalous information.
Motions in proteins.

Publisher Summary The chapter discusses the motions in proteins. Gelation of gelatin or precipitation of casein with mild acid are examples of reversible changes in which structural motility of the protein chains or subunits is recognized as playing a part. The sometimes reversible spreading of monolayers derived from mondisperse proteins provides some of the first evidence for the true plasticity of protein molecules and paved the way for the elegant demonstration of reversible conformational transitions. The tracing of the passage of an unfolded polypeptide chain to the compact, native structure is a primary concern of protein chemistry. One segment of polypeptide chain adapts its backbone and sidechain conformation to the structure of another segment in the process of forming the compact, functional structure of a protein was made particularly vivid by experiments on the reassociation of cleaved fragments. Overall translational and rotational motion is observed with a protein in solution, apart from any intramolecular motions. These overall motions are those that remain if the protein molecule is treated as a rigid matrix. Rotational reorientation of intramolecular components involves rotations about individual interatomic bonds. Concerted motions in proteins involve the movement of groups of side chains or segments of backbone relative to other structures. Motions of interacting ions and small molecules produce fluctuations in protein structure in addition to Brownian transfer of momentum. Time scales of various types of motions are important both for experimental recognition of the time-dependent processes and for analyzing their importance in the functional molecular mechanics. The chapter also discusses the dominant methods of observation that provide information about frequencies and amplitudes of motions in proteins.
Distributed Computations by Active Network Calls

Key requirements for Active Networks are their ability to integrate heterogeneous components; to rely on widely accepted programming models, to support availability in case of failure, and to achieve good performance. However, those requirements are conflicting - e.g. using Java based programming systems to provide heterogeneity, typically results in poor performance. We address this problem by introducing a three-level architecture that a) makes a minor change in the conventional programming language model - introduces the remote storage class to support code distribution and its parallel execution, b) uses a separate user interface to establish active sessions, to specify the topology for a given distributed computation, and to replicate the sessions, and c) achieves efficient run-time distribution through a new mechanism, called active network calls (ANC), that performs computations through low cost asynchronous operations and active capsules. Data flow and operation flow are separated thus allowing a high degree of parallelism.
Can laser light cool semiconductors

Laser cooling in semiconductors is theoretically investigated including arbitrary external efficiency and photon recycling. Experimental conditions needed to attain net cooling in GaAs are derived.
Tissue-specific expression of Cre recombinase from the Tgfb3 locus

Tgfb3, a member of the TGF-beta superfamily, is tightly regulated, both spatially and temporally, during embryogenesis. Previous mouse knockout studies have demonstrated that Tgfb3 is absolutely required for normal palatal fusion and pulmonary development. We have generated a novel tool to ablate genes in Tgfb3-expressing cells by targeting the promoterless Cre-pgk-Neo cassette into exon 1 of the mouse Tgfb3 gene, which generates a functionally null Tgfb3 allele. Using the Rosa26 reporter assay, we demonstrate that Cre-induced recombination was already induced at embryonal day 10 (E10) in the ventricular myocardium, limb buds, and otic vesicles. At E14, robust recombination was detected in the prefusion palatal epithelium. Deletion of the TGF-beta type I receptor Alk5 (Tgfbr1) specifically in Tgfb3 expressing cells using the Tgfb3-Cre driver line lead to a cleft palate phenotype similar to that seen in conventional Tgfb3 null mutants. In addition, Alk5/ Tgfb3-Cre mice displayed hydrocephalus, and severe intracranial bleeding due to germinal matrix hemorrhage.
Aging is associated with an impaired coronary microvascular response to vascular endothelial growth factor in patients.

Objective If growth factor and cell-based therapy are to become therapeutic strategies, a better understanding of their physiologic effects in various patient populations will need to be gained. In this study, we examined age-dependent differences in vascular endothelial growth factor signaling before and after cardioplegia/cardiopulmonary bypass. Methods Atrial tissue and peripheral blood of patients undergoing surgery were examined before and after cardioplegia/cardiopulmonary bypass. Patients were divided into younger (age + progenitor cells before and after cardioplegia/cardiopulmonary bypass were compared between groups. Results Advanced age was associated with impaired basal coronary microvascular response to vascular endothelial growth factor (−13% ± 5% at 10 −10 mol/L vascular endothelial growth factor; P = .04), whereas basal relaxation response to substance P and sodium nitroprusside were similar between groups. After cardioplegia/cardiopulmonary bypass, the microvascular response to vascular endothelial growth factor significantly worsened in both groups (both P ≤ .05), and response to substance P ( P = .05) was significantly impaired only in older patients. Vascular endothelial growth factor expression increased after cardioplegia/cardiopulmonary bypass in older ( P = .01 vs before cardioplegia/cardiopulmonary bypass), but not younger ( P = .20) patients. Expression of other signaling molecules was unaffected by age or surgery. Circulating CD34 + cells increased after cardioplegia/cardiopulmonary bypass in all patients but to a greater extent in younger patients ( P = .01). Conclusions The coronary microvascular response to vascular endothelial growth factor is impaired in older patients. Combined with reduced progenitor cell mobilization, these results suggest new mechanisms for reduced angiogenic response in older patients.
Applied Physiology of Triathlon

The triathlon is a 3-event endurance sport in which athletes compete sequentially in swimming, cycling and running. The primary determinant of success is the ability to sustain a high rate of energy expenditure for prolonged periods of time. Exercise training-induced physiological adaptations in virtually all systems of the body allow the athlete to accomplish this. Aerobic capacity (measured as maximal oxygen uptake, VO2max), economy of motion (submaximal VO2) and fractional utilisation of maximal capacity (%VO2max) reflect the integrated responses of these physiological adaptations. Numerous studies have reported relatively high mean VO2max values for various groups of triathletes that are comparable to those reported for athletes in single-event endurance sports and clearly above those reported for untrained individuals. In shorter distance triathlons and in studies using recreational (rather than elite) triathletes, VO2max is related to performance in the corresponding event of the triathlon (e.g. tethered swimming VO2max with swim time). In longer events and with more elite triathletes, VO2max correlates less well with performance. The physiological adaptations that correspond to and facilitate improved VO2max occur centrally in the cardiovascular system, centred on increased maximal cardiac output, and peripherally in the metabolic systems, centred around increased arterio-venous O2 (a-v O2) difference. While a high VO2max in individuals is clearly of importance to triathlon performance, energy output must be sustained for long periods of time, making economy of motion also very important. Studies suggests that competitive swimmers have better swimming economy than triathletes. However, since many triathletes have previously been competitive swimmers this finding is questionable. The finding suggests that triathletes from nonswimming backgrounds would benefit from improving swimming technique rather than concentrating training workouts solely on distance. In cycling and running, comparison studies have not been done. Economy of motion in swimming, cycling and running have all been found to be correlated with comparable event performance. Training to improve swimming economy can be done without prior exercise, but training to improve swimming economy can be done without prior exercise, but training to improve cycling and running economy should take the multimode nature of a triathlon into consideration. That is, swimming should precede cycling economy training, and cycling should precede running economy training. Cardiovascular, metabolic and neuromuscular adaptations are the main physiological correlates of improved movement economy. Since exercise-induced stress on most physiological systems is based on relative, rather than absolute, exercise intensity, training and racing intensities are frequently quantified as a percentage of maximal capacity of %VO2max.(ABSTRACT TRUNCATED AT 400 WORDS)
The gene encoding translation initiation factor 3 is highly conserved in gram-negative bacteria

Abstract A 1.1-kb Hpa I fragment of the Escherichia coli chromosome containing the gene for translation initiation factor 3 was employed as a probe in heterologous hybridization to chromosomal DNA from a variety of other procaryotes. Positive hybridization was observed to DNA derived from all gram-negative bacteria tested. In contrast, no hybridization to DNA from gram-positive bacteria was detected. In addition, homologous sequences were found in Euglena gracilis chloroplast DNA, while this was not the case with Saccharomyces cerevisiae mitochondrial DNA. These results are discussed in light of existing data on the components and mechanism of translation initiation in the various organisms and organelles employed in this study.
State of chlorophyll a in vitro and in vivo from electronic transition spectra, and the nature of antenna chlorophyll.

Abstract The computer deconvolution of the red envelopes of visible spectra of chlorophyll a solutions in dry nonpolar solvents is described. In solvents such as carbon tetrachloride and benzene chlorophyll a is present in dimer form in the concentration range of 10−6–10−2. In solvents such as hexane and n-alkanes oligomeric species of chlorophyll a are present. The relative intensities of the Gaussian components used in the spectral deconvolution can be related to the size and conformation of the chlorophyll a aggregates. While the computer deconvolution is basically a heuristic method, it is suggested that it is based on a sound physical rationale. A comparison of the computer deconvoluted visible spectra of photosynthetic organisms with those of solutions of chlorophyll a oligomers in nonpolar media provides good evidence that antenna chlorophyll in green plants has spectral properties that are very similar, if not identical, to those of chlorophyll a oligomers, (chlorophyll2)n.
Effect of cytochalasins on surfactant release from alveolar type II cells.

Abstract Cytochalasins enhanced surfactant secretion from primary cultures of [ 3 H]choline-labeled type II epithelial cells from the rat. Cytochalasins A, B, C, D and dihydrocytochalasin B enhanced secretion of phosphatidyl-[ 3 H]choline ([ 3 H]PC) in a dose-dependent manner with EC 50 values of 1, 2, 0.5, 0.1 and 1 μM for cytochalasins A, B, C, D and dihydrocytochalasin B, respectively. Only cytochalasin A caused significant cytotoxicity as determined by release of the intracellular enzyme lactate dehydrogenase (EC 1.1.1.17). Dose responses of surfactant release induced by cytochalasins B, C and D were biphasic; maximal release was observed between 0.1–1.0 μM for cytochalasins C and D between 1 and 10 μM for cytochalasin B. Secretion decreased toward control levels at concentrations of cytochalasin above these maximal concentrations. Increased rates of [ 3 H]PC release were noted between 1 and 3 h after exposure to cytochalasin D. Increased rates of surfactant release induced by cytochalasin D were additive to release induced by the β-adrenergic agonist, terbutaline, or forskolin, although cytochalasin D had no direct effect on cytosolic cyclic AMP levels. Changes in cell shape and microfilament organization were observed by phase-contrast microscopy and fluorescence microscopy using rhodamine-conjugated phalloidin after exposure of the isolated type II cells to cytochalasin D. Disruption of microfilaments associated with lamellar bodies of the purified type II cells occurred after treatment with cytochalasin D. Cytochalasin D augmented surfactant release from purified type II cells and disrupted the microfilament structure of those cells, supporting the hypothesis that alterations in microfilaments are associated with surfactant release.
Ligand effects on the redox behavior of bimetallic tungsten(0)/ferrocene(II) complexes

This work presents a synthesis of bimetallic tungsten(0)/ferrocene(II) complex dppf[W(CO)3PMe3] and detailed comparisons of the redox behavior of dppf[W(CO)3PMe3], dppf[W(CO)4], and dppf[W(CO)3CH3CN]. Reaction of PMe3 with dppf[W(CO)3CH3CN] in dichloromethane under an inert atmosphere yields dppf[W(CO)3PMe3]. Slow cooling of the column purified product yields yellow blocks suitable for X-ray diffraction analysis. Structural, spectroscopic, electrochemical, and computational studies show that all three complexes have multiple redox events corresponding to tungsten and ferrocene oxidation. The complexes’ distal tungsten ligands tune the first redox event over a broad range, from � 37 to � 200 meV versus ferrocene. Computational studies suggest that the ligand tunes the tungsten moiety’s redox potential, changing the first redox event from ferrocene(II) oxidation to tungsten(0) oxidation. This bimetallic complex is thus an interesting candidate for redox-based sensing architectures.
Racial Differences in Childlessness: A Centennial Review

This article reviews black-white childlessness differences over the past century. These differences have been attributed to inequalities in social and health conditions. The historically greater rate of black childlessness has been treated as the result of pathological sterility or pregnancy loss due to sexually transmitted diseases (STDs), malnutrition, and inadequate medical care. Conversely, white childlessness has been viewed as the product of decisions to be child-free, facilitated or encouraged by such things as prolonged schooling, the sex-role revolution, and effective contraception. Yet it is suggested that childlessness in both races has been shaped by the same basic factors, including social mobility, birth control, and changing family norms. Moreover, as a result of socioeconomic gains by blacks, patterns of marital childlessness by race are becoming alike, and voluntary childlessness may be growing among blacks as well as whites.
Hypertension in the aged: A pathophysiologic basis for treatment

According to major surveys, hypertension is found in over half the population aged 65 years or over. In this age group, systolic blood pressure is at least as important as diastolic blood pressure as a predictor of cardiovascular morbidity and mortality. Overall, the presence of hypertension is associated with approximately a threefold increase in the likelihood of major events. Differing factors contribute to the hypertension. Loss of proximal arterial compliance, affecting the larger conduit vessels, occurs often with aging and explains the tendency for systolic pressure to increase while diastolic pressure remains constant or even decreases. A loss of baroreceptor sensitivity also may contribute to hypertension. There is an increase in responsiveness of the sympathetic nervous system and an enhanced sensitivity to its effects in the elderly, perhaps reflecting a decline in the buffering activity of peripheral vascular beta receptors. It is possible, too, that sodium retention may contribute to hypertension in some older patients. Although diuretics traditionally have been the mainstay of treatment in these patients, it is now recognized that other classes of antihypertensive agents may be equally as effective yet less prone to metabolic or symptomatic adverse events. Sympatholytic drugs, calcium channel blockers and angiotensin-converting enzyme inhibitors, either as monotherapy or in combination with low-dose diuretics, have been shown to be efficacious in the elderly. These agents also can produce regression of left ventricular hypertrophy, an additional property that may contribute to a reduction in serious cardiac complications.
Interaction Between Implanted Ions and Intrinsic Defects in Silica

High purity silica (Spectrosil) samples were implanted with Ti, Cr, Mn, Fe and Cu at doses ranging from 1.0 to 5.0×1015 ions/cm2 at 160 keV and 2.6 μA/cm2. The optical absorption extinction coefficients per ion were measured from 1.8 to 6.0 eV. In all samples there was an increase in absorption over the unimplanted sample at energies ≥4.6 eV. The increase in absorption at 5.1 eV and 5.7 eV is attributed to B2(E”) centers and E’ centers respectively. The relative values of the extinction coefficients of these bands are attributed to the relative oxygen activities of the TMI relative to the SiO2 host substrate.
Purification and partial characterization of prostaglandin D2 11-keto reductase in rabbit liver.

Abstract The cytoplasmic NADPH-dependent prostaglandin D2 11-keto reductase from rabbit liver was purified by a series of chromatographic procedures including isoelectric focusing. The enzyme catalyzed the conversion of prostaglandin D2 to prostaglandin F2α and had a pH optimum of 7.0–7.5, and an isoelectric point of 5.8. The molecular weight was estimated to be 66 000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Enzymic activity was time and concentration dependent and required NADPH as cofactor.
Evaluation of Patient-Related and Procedure-Related Factors Contributing to Pneumothorax Following Thoracentesis

Objective To evaluate patient-related and procedure-related risk factors for thoracentesis-related pneumothorax. Design Prospective, nonrandomized cohort study. Setting Pulmonary Special Procedures Unit of a university medical center. Methods Thoracentesis using either a 22-gauge, a Boutin, or a Cope needle (depending on availability and operator preference) was performed by the pulmonary faculty or by pulmonary physicians-in-training under faculty supervision. In order to control for effusion size and the presence of loculations, chest radiography and pleural ultrasonography were performed prior to each thoracentesis. Potential patient-related and procedure-related risk factors for pneumothorax were analyzed at the procedure level using the presence or absence of pneumothorax on the postprocedure chest radiograph as the sole outcome variable. Results Two hundred fifty-five thoracenteses were performed in 205 adult patients (113 men and 92 women; mean age, 58.8 ± 18 years) over a 31/2-year period. One hundred fifty procedures were performed for diagnostic purposes, 28 procedures were performed for therapeutic purposes, and 77 procedures were performed for both diagnostic and therapeutic purposes. Based on the radiographic criteria, 152 effusions (60%) were small. Loculations were present in 76 patients (30%). Pneumothoraces occurred in 14 instances (5.4%), and chest tube drainage was required in 2 instances (0.78%). Hospitalization status, critical illness, effusion size or type, presence of loculations, operator, needle type, amount of fluid withdrawn, occurrence of dry tap, and type of thoracentesis were not associated with an increased frequency of pneumothorax. The only predictor variable demonstrating statistical significance was repeated thoracentesis. Conclusion The results of a bivariate analysis suggest that pneumothorax following thoracentesis is a rare event that is not easily predictable when the procedure is performed by experienced operators in a controlled setting.
Pulsed mode constant current iontophoretic transdermal metaprolol tartrate delivery in established acute hypertensive rabbits

Pulsed mode constant current iontophoretic enhancement was used for transdermal administration of the beta-adrenoceptor blocking agent metoprolol tartrate to spontaneously hypertensive rabbits (n=4). Systolic pressure was reduced from a pre-treatment pressure of 126 ± 9 mm Hg to a post-treatment pressure of 86 ± 11 mm Hg (P < 0.05) within two hours. Diastolic pressure was lowered during this time from 99 ± 7 mm Hg to 72 ± 10 mm Hg (P < 0.05).
Alcohol detoxification and withdrawal seizures: clinical support for a kindling hypothesis.

Abstract There has been speculation that a kindling model may have applicability to alcohol withdrawal syndromes and seizures, suggesting that repeated alcohol withdrawals may lead to increased severity of subsequent withdrawals. We evaluated historical and clinical variables of a group of male alcoholics with ( n = 25) and without ( n = 25) alcohol withdrawal seizures. We found that the number of detoxifications appeared to be an important variable in the predisposition to withdrawal seizures. The withdrawal seizure group had 12 of 25 (48%) patients with 5 or more previous detoxifications, compared to only 3 of 25 (12%) of the control group. A relationship between alcohol use history and withdrawal seizures was not supported by the data. These findings support the concept that previous alcohol withdrawals may "kindle" more serious subsequent withdrawal symptomatology, ultimately culminating in withdrawal seizures.
XLink and open hypermedia systems: a preliminary investigation

XLink is an emerging Internet standard designed to support the linking of XML documents. We present preliminary work on using XLink as an export format for the links of an open hypermedia system. Our work provides insights into XLink’s suitability as a vehicle for extending the benefits of open hypermedia to the rapidly evolving world of XML.
GIGA+: scalable directories for shared file systems

There is an increasing use of high-performance computing (HPC) clusters with thousands of compute nodes that, with the advent of multi-core CPUs, will impose a significant challenge for storage systems: The ability to scale to handle I/O generated by applications executing in parallel in tens of thousands of threads. One such challenge is building scalable directories for cluster storage - i.e., directories that can store billions to trillions of entries and handle hundreds of thousands of operations per second.