cssi/SciSciGPT-SciSciNet huggingface dataset:
Understanding how an amphicarpic species with a mixed mating system responds to fire: a population genetic approach

Amphicarpic plants produce both above-ground and below-ground seeds. Because below-ground seeds are protected in the soil and may maintain viability when above-ground conditions are stressful, they were proposed as an adaptation to recolonize a site after disturbance. However, whether below-ground seeds are the main colonizers after a disturbance remains unknown. Our goal was to understand whether recolonization by an amphicarpic species after fire was accomplished primarily through germination of seeds produced above-ground or below-ground. We investigated Polygala lewtonii, an amphicarpic, perennial species endemic to fire-prone Florida sandhill and scrub, where fire kills plants but subsequently increases recruitment and population sizes. Polygala lewtonii produces three flower types: above-ground chasmogamous flowers and above-ground and below-ground cleistogamous flowers, with previous research demonstrating chasmogamous flowers produce a much greater proportion of seeds than cleistogamous flowers. We quantified outcrossing in seeds produced by chasmogamous flowers to determine whether it differed from the 100 % self-fertilized below-ground seeds. Approximately 25 % of seeds from chasmogamous flowers showed evidence of cross-pollination. Assuming that chasmogamous flowers produce the majority of the above-ground seeds, as was shown previously, this indicates it is possible to differentiate between germination by above-ground versus below-ground seeds in post-fire colonization. We next compared genetic diversity, admixture, inbreeding and population genetic structure pre- and post-fire. If fire promoted germination of chasmogamous seeds, heterozygosity and admixture would increase, and genetic structure and inbreeding would decrease. Instead, inbreeding and genetic structure increased and admixture decreased, suggesting that the below-ground selfed seeds (with limited dispersal ability) increased their contribution to the population after fire, possibly because fire reduced above-ground seed viability. Additionally, new alleles not found previously in range-wide analyses emerged from the seed bank post-fire. These results suggest that amphicarpy is a powerful adaptation to preserve genetic variation, maintain adaptive potential and promote rapid post-fire colonization.
Genome-Wide Identification of Tomato Xylem Sap Fitness Factors for Three Plant-Pathogenic Ralstonia Species

Plant-pathogenic Ralstonia spp. colonize plant xylem and cause wilt diseases on a broad range of host plants. To identify genes that promote growth of diverse Ralstonia strains in xylem sap from tomato plants, we performed genome-scale genetic screens (random barcoded transposon mutant sequencing screens [RB-TnSeq]) in three strains spanning the genetic, geographical, and physiological range of plant-pathogenic Ralstonia: Ralstonia solanacearum IBSBF1503, Ralstonia pseudosolanacearum GMI1000, and Ralstonia syzygii PSI07. Contrasting mutant fitness phenotypes in culture media versus in xylem sap suggest that Ralstonia strains are adapted to ex vivo xylem sap and that culture media impose foreign selective pressures. Although wild-type Ralstonia grew in sap and in rich medium with similar doubling times and to a similar carrying capacity, more genes were essential for growth in sap than in rich medium. Each strain required many genes associated with envelope remodeling and repair processes for full fitness in xylem sap. These genes were associated with peptidoglycan peptide formation (murI), secretion of periplasmic proteins (tatC), periplasmic protein folding (dsbA), synthesis of osmoregulated periplasmic glucans (mdoGH), and lipopolysaccharide (LPS) biosynthesis. Mutant strains with mutations in four genes had strong, sap-specific fitness defects in all strain backgrounds: murI, thiC, purU, and a lipoprotein (RSc2007). Many amino acid biosynthesis genes were required for fitness in both minimal medium and xylem sap. Multiple mutants with insertions in virulence regulators had gains of fitness in culture media and neutral fitness in sap. Our genome-scale genetic screen identified Ralstonia fitness factors that promote growth in xylem sap, an ecologically relevant condition. IMPORTANCE Traditional transposon mutagenesis genetic screens pioneered molecular plant pathology and identified core virulence traits like the type III secretion system. TnSeq approaches that leverage next-generation sequencing to rapidly quantify transposon mutant phenotypes are ushering in a new wave of biological discovery. Here, we have adapted a genome-scale approach, random barcoded transposon mutant sequencing (RB-TnSeq), to discover fitness factors that promote growth of three related bacterial strains in a common niche, tomato xylem sap. Fitness of the wild type and mutants show that Ralstonia spp. are adapted to grow well in xylem sap from their natural host plant, tomato. Our screen identified multiple sap-specific fitness factors with roles in maintaining the bacterial envelope. These factors include putative adaptations to resist plant defenses that may include antimicrobial proteins and specialized metabolites that damage bacterial membranes.
Universal linear optics by programmable multimode interference

We introduce a constructive algorithm for universal linear electromagnetic transformations between the N input and N output modes of a dielectric slab. The approach uses out-of-plane phase modulation programmed down to N2 degrees of freedom. The total area of these modulators equals that of the entire slab: our scheme makes optimal use of the available area for optical modulation. We also present error correction schemes that enable high-fidelity unitary transformations at large N. This “programmable multimode interferometer” (ProMMI) thus translates the algorithmic simplicity of Mach-Zehnder meshes into a holographically programmed slab, yielding DoF-limited compactness and error tolerance while eliminating the dominant sidewall-related optical losses and directional-coupler-related patterning challenges.
A likelihood-based approach for multivariate categorical response regression in high dimensions

We propose a penalized likelihood method to fit the bivariate categorical response regression model. Our method allows practitioners to estimate which predictors are irrelevant, which predictors on...
Attention improves information flow between neuronal populations without changing the communication subspace.

Summary Visual attention allows observers to change the influence of different parts of a visual scene on their behavior, suggesting that information can be flexibly shared between visual cortex and neurons involved in decision making. We investigated the neural substrate of flexible information routing by analyzing the activity of populations of visual neurons in the medial temporal area (MT) and oculo-motor neurons in the superior colliculus (SC) while rhesus monkeys switched spatial attention. We demonstrated that attention increases the efficacy of visuomotor communication: trial-to-trial variability in SC population activity could be better predicted by the activity of the MT population (and vice versa) when attention was directed toward their joint receptive fields. Surprisingly, this improvement in prediction was not explained by changes in the dimensionality of the shared subspace or in the magnitude of local or shared pairwise noise correlations. These results lay a foundation for future theoretical and experimental studies into how visual attention can flexibly change information flow between sensory and decision neurons.
Pricing and energy trading in peer-to-peer zero marginal-cost microgrids

Efforts to utilize 100% renewable energy in community microgrids require new approaches to energy markets and transactions to efficiently address periods of scarce energy supply. In this paper we contribute to the promising approach of peer-to-peer (P2P) energy trading in two main ways: analysis of a centralized, welfare-maximizing economic dispatch that characterizes optimal price and allocations, and a novel P2P system for negotiating energy trades that yields physically feasible and at least weakly Pareto-optimal outcomes. Our main results are 1) that optimal pricing is insufficient to induce agents with batteries to take optimal actions, 2) a novel P2P algorithm to addresses this while keeping private information, 3) a formal proof that this algorithm converges to the centralized solution in the case of two agents negotiating for a single period, and 4) numerical simulations of the P2P algorithm performance with up to 10 agents and 24 periods that show it converges on average to total welfare within 0.1% of the social optimum in on the order of 10s to 100s of iterations, increasing with the number of agents, time periods, and total storage capacity.
Active cytoskeletal composites display emergent tunable contractility and restructuring.

The cytoskeleton is a model active matter system that controls processes as diverse as cell motility and mechanosensing. While both active actomyosin dynamics and actin-microtubule interactions are key to the cytoskeleton’s versatility and adaptability, an understanding of their interplay is lacking. Here, we couple microscale experiments with mechanistic modeling to elucidate how connectivity, rigidity, and force-generation affect emergent material properties in composite networks of actin, tubulin, and myosin. We use multi-spectral imaging, time-resolved differential dynamic microscopy and spatial image autocorrelation to show that ballistic contraction occurs in composites with sufficient flexibility and motor density, but that a critical fraction of microtubules is necessary to sustain controlled dynamics. The active double-network models we develop, which recapitulate our experimental findings, reveal that while percolated actomyosin networks are essential for contraction, only composites with comparable actin and microtubule densities can simultaneously resist mechanical stresses while supporting substantial restructuring. The comprehensive phase map we present not only provides important insight into the different routes the cytoskeleton can use to alter its dynamics and structure, but also serves as a much-needed blueprint for designing cytoskeleton-inspired materials that couple tunability with resilience and adaptability for diverse applications ranging from wound healing to soft robotics.
Visualization of acoustic power flow in suspended thin-film lithium niobate phononic devices

We report direct visualization of gigahertz-frequency acoustic waves in lithium niobate phononic circuits. Primary propagation parameters, such as the power flow angle and propagation loss, are measured by transmission-mode microwave impedance microscopy. Using a fast Fourier transform, we can separately analyze forward and backward propagating waves and quantitatively evaluate the propagation loss. Our work provides insightful information on the propagation, diffraction, and attenuation in piezoelectric thin films, which is highly desirable for designing and optimizing phononic devices for microwave signal processing.
Imaging the extent and location of spatiotemporally distributed epileptiform sources from MEG measurements

Abstract Non-invasive MEG/EEG source imaging provides valuable information about the epileptogenic brain areas which can be used to aid presurgical planning in focal epilepsy patients suffering from drug-resistant seizures. However, the source extent estimation for electrophysiological source imaging remains to be a challenge and is usually largely dependent on subjective choice. Our recently developed algorithm, fast spatiotemporal iteratively reweighted edge sparsity minimization (FAST-IRES) strategy, has been shown to objectively estimate extended sources from EEG recording, while it has not been applied to MEG recordings. In this work, through extensive numerical experiments and real data analysis in a group of focal drug-resistant epilepsy patients’ interictal spikes, we demonstrated the ability of FAST-IRES algorithm to image the location and extent of underlying epilepsy sources from MEG measurements. Our results indicate the merits of FAST-IRES in imaging the location and extent of epilepsy sources for pre-surgical evaluation from MEG measurements.
Effects of spectral light quality on the growth, productivity, and elemental ratios in differently pigmented marine phytoplankton species

The recent advancement in LED technology led many incubator manufacturers and research labs to switch to these more efficient, yet spectrally restricted, light sources. Potential effects of commercially available broad range “white” light systems on phytoplankton growth, productivity, light absorption spectra, and cellular composition have not yet been characterized but could affect our interpretation of lab-based projections on responses to environmental changes. In this study, we investigated such effects using cultures of Prochlorococcus marinus, Synechococcus sp., and Thalassiosira weissflogii grown under three different commercially available LED lights as well as one fluorescent growth light. Photosynthetically active radiation was equal for each species, while photosynthetically usable radiation differed among the combinations of species and treatments. Growth rate was unaffected across species, yet all species displayed changes in cellular carbon, nitrogen, and chlorophyll a quotas as a direct response to the different light spectra. 14C-based primary productivity was also affected in P. marinus and T. weissflogii. Analysis of pigment ratios and photophysiological data indicated changes in the photoacclimation state between different light environments. The results of this study show that these species undergo changes in underlying cellular metabolism which in turn affect cellular composition while keeping specific growth constant. The data presented here illustrate ecophysiological responses of differently pigmented species when grown under different artificial growth light spectra. These cellular acclimation responses should be considered when designing laboratory-based incubation experiments, especially when comparing responses to specific changes in environmental conditions, or when implementing physiological parameters, derived from laboratory experiments, into numerical models.
Why do Black Holes Trace Bulges (& Central Surface Densities), Instead of Galaxies as a Whole?

Previous studies of fueling black holes (BHs) in galactic nuclei have argued (on scales ~0.01-1000pc) accretion is dynamical with inflow rates $\dot{M}\sim\eta\,M_{\rm gas}/t_{\rm dyn}$ in terms of gas mass $M_{\rm gas}$, dynamical time $t_{\rm dyn}$, and some $\eta$. But these models generally neglected expulsion of gas by stellar feedback, or considered extremely high densities where expulsion is inefficient. Studies of star formation, however, have shown on sub-kpc scales the expulsion efficiency $f_{\rm wind}=M_{\rm ejected}/M_{\rm total}$ scales with the gravitational acceleration as $(1-f_{\rm wind})/f_{\rm wind}\sim\bar{a}_{\rm grav}/\langle\dot{p}/m_{\ast}\rangle\sim \Sigma_{\rm eff}/\Sigma_{\rm crit}$ where $\bar{a}_{\rm grav}\equiv G\,M_{\rm tot}(<r)/r^{2}$ and $\langle\dot{p}/m_{\ast}\rangle$ is the momentum injection rate from young stars. Adopting this as the simplest correction for stellar feedback, $\eta \rightarrow \eta\,(1-f_{\rm wind})$, we show this provides a more accurate description of simulations with stellar feedback at low densities. This has immediate consequences, predicting e.g. the slope and normalization of the $M-\sigma$ and $M-M_{\rm bulge}$ relation, $L_{\rm AGN}-$SFR relations, and explanations for outliers in compact Es. Most strikingly, because star formation simulations show expulsion is efficient ($f_{\rm wind}\sim1$) below total-mass surface density $M_{\rm tot}/\pi\,r^{2}<\Sigma_{\rm crit}\sim3\times10^{9}\,M_{\odot}\,{\rm kpc^{-2}}$ (where $\Sigma_{\rm crit}=\langle\dot{p}/m_{\ast}\rangle/(\pi\,G)$), BH mass is predicted to specifically trace host galaxy properties above a critical surface brightness $\Sigma_{\rm crit}$ (B-band $\mu_{\rm B}^{\rm crit}\sim 19\,{\rm mag\,arcsec^{-2}}$). This naturally explains why BH masses preferentially reflect bulge properties or central surface-densities ($\Sigma_{1\,{\rm kpc}}$), not 'total' galaxy properties.
Religious Conviction in Liberal Politics

What role should a citizen's religious convictions play in her political activities? Is she, for example, permitted to decide on the basis of her religious convictions to support laws that criminalize abortion or discourage homosexual relations? Christopher Eberle is deeply at odds with the dominant orthodoxy among political theorists about the relation of religion and politics. His argument is that a citizen may responsibly ground her political commitments on religious beliefs, even if her only reasons for her political commitments are religious in nature. His ideal of citizenship allows citizens to engage in politics without privatizing their religious commitments, and yet does not license mindless and intransigent sectarianism. An inherently controversial book that offers a substantial challenge to political liberalism, it will be read by students and professionals in philosophy, political science, law and religious studies, and general readers seeking insight into the relationship between religious commitments and liberal politics.
Optimality of a Heuristic Sequencing Technique

The development of simple heuristic planning techniques which are capable of solving problems of the dimensions encountered in real-world water resources systems is important. However, guidelines on the optimality of such techniques must be developed before their potential use in water resources planning can be fully realized. In this note, the writer has provided guidelines for the optimality of an ingenious heuristic project sequencing technique developed by Tsou, Mitten, and Russell and demonstrated how their technique can be modified and used with decomposition in order to solve a more general class of problems. (Technical Note of the Technical Council on Water Resources Planning and Management)
Evaluation of tizanidine as a marker of canine CYP1A2 activity

The dog CYP1A2 enzyme is likely an important contributor to the metabolism of veterinary drugs. Dog CYP1A2 is expressed in liver, plus it is inducible and polymorphic, creating the potential for intersubject differences in pharmacokinetics. Hence, the ability to probe dog CYP1A2 activity and inhibition is relevant toward veterinary drug development and drug-drug interaction assessment. Previous studies have relied on human probes with questionable specificity for CYP1A2, so it was hypothesized that recombinant CYP1A2 could be used to find a specific CYP1A2 substrate. Intrinsic clearance experiments demonstrated that tizanidine was a substrate of CYP1A2. Profiling of tizanidine metabolites generated by CYP1A2 identified the imidazole metabolite that was detectable in dog plasma. The imidazole metabolite was subsequently used to evaluate tizanidine as a CYP1A2 probe. Co-administration of the CYP1A inhibitor enrofloxacin with tizanidine significantly decreased (30%; n = 3) the formation of the imidazole metabolite vs. control experiments. As enrofloxacin is a weak inhibitor, further studies are required to confirm the sensitivity of tizanidine as an in vivo probe. However, tizanidine may be a more selective CYP1A2 probe than phenacetin when conducting in vitro studies due to the presence of other phenacetin-metabolizing enzymes in dog liver microsomes.
Electrical and dielectric characteristics of magnetic ceramics of Mn1−xNixFe2O4 spinel nanoferrites

AbstractCeramics materials of the class of spinel nanoferrites of Mn1−xNixFe2O4 (x = 0·00, 0·025, 0·50, 0·75 and 1·00) of 13–25 nm particle sizes have been investigated for their electrical and dielectric characteristics. The dc electrical resistivity was measured and found to decrease with an increase in x to follow the Verwey mechanism because of the increase in electron hopping between the Fe2+ tetrahedral site (A site) and the Fe3+ octahedral site (B site). In addition, the resistivity of ferrites was observed to decrease with an increase in temperature, confirming their semiconductor characteristics. The dielectric constant and the dielectric loss factor were found to decrease as the frequency increased, following the Maxwell–Wagner interfacial type of polarisation. The study of the electrical properties of the prepared ferrites suggests their usefulness in important applications in electronic devices in reducing power losses due to an increase in conductivity caused by the increment in Ni concentrat...
A constitutive theory for shape memory polymers. Part I: Large deformations

Abstract A constitutive theory is developed for shape memory polymers. It is to describe the thermomechanical properties of such materials under large deformations. The theory is based on the idea, which is developed in the work of Liu et al. [2006. Thermomechanics of shape memory polymers: uniaxial experiments and constitutive modeling. Int. J. Plasticity 22, 279–313], that the coexisting active and frozen phases of the polymer and the transitions between them provide the underlying mechanisms for strain storage and recovery during a shape memory cycle. General constitutive functions for nonlinear thermoelastic materials are used for the active and frozen phases. Also used is an internal state variable which describes the volume fraction of the frozen phase. The material behavior of history dependence in the frozen phase is captured by using the concept of frozen reference configuration. The relation between the overall deformation and the stress is derived by integration of the constitutive equations of the coexisting phases. As a special case of the nonlinear constitutive model, a neo-Hookean type constitutive function for each phase is considered. The material behaviors in a shape memory cycle under uniaxial loading are examined. A linear constitutive model is derived from the nonlinear theory by considering small deformations. The predictions of this model are compared with experimental measurements.
Leptin responses to glucose infusions in obesity-prone rats.

The secretion of leptin is dually regulated. In fasting animals, plasma leptin concentrations reflect body fat stores, whereas the incremental leptin response to fasting or refeeding most likely re...
Perspective: Physiological Role(s) of the Vascular Myogenic Response

The vascular myogenic response is an inherent property of VSM in the walls of small arteries and arterioles, allowing these principal resistance segments of the microcirculation to respond to changes in transmural pressure. Elevated intraluminal pressure leads to myogenic constriction, whereas reduced pressure leads to myogenic dilation. This review focuses on the physiological significance of the myogenic response in microvascular networks. First, historical concepts related to the detection of stretch by the vessel wall are reviewed, including the wall tension hypothesis, and the implications of the proposal that the arteriolar network responds to Pp changes as a system of series-coupled myogenic effectors. Next, the role of the myogenic response in the local regulation of blood flow and/or Pc is examined. Finally, the interaction of myogenic constriction and dilation with other local control mechanisms, including metabolic, neural and shear-dependent mechanisms, is discussed. Throughout the review, an attempt is made to integrate historical and current literature with an emphasis on the physiological role, rather than the underlying signaling mechanisms, of this important component of vascular control.
Ultraviolet photodissociation mass spectrometry of bis-aryl hydrazone conjugated peptides.

Ultraviolet photodissociation (UVPD) at 355 nm was used to rapidly identify peptides which had been chemically conjugated through bis-aryl hydrazone (BAH) moieties. The two biomolecules of interest were separately tagged to introduce either an aldehyde or a hydrazine and then conjugated together through these functional groups to from the UV-chromogenic BAH-group. In a mock mixture of peptides, UVPD was used to screen for the BAH-conjugated peptides in direct infusion ESI-UVPD-MS and online LC-UVPD-MS methods by comparing the abundances of the ions with the laser off and with the laser on. Only the BAH-conjugated peptides were observed to photodissociate upon exposure to UV irradiation, thus affording excellent selectivity for the pinpointing the relevant conjugated peptides in a complex mixture of nonconjugated peptides. UVPD analysis of conjugated model peptides indicated that the UVPD efficiencies of these species were charge state dependent. BAH-conjugated peptides that had a mobile proton which could...
Electrical and SEM testing of absorber defectivity in the plated-gold process for x-ray masks

It is widely recognized that the 1:1 x-ray mask is the most technically challenging aspect of proximity x-ray lithography, since high resolution and precise pattern placement must be achieved completely free of defects. SEM investigation is an excellent tool for x-ray mask inspection. However, it is sometimes assumed that only the SEM has sufficient resolution to perform meaningful defect detection on x-ray masks. An electrically probed test chip pattern for x-ray mask defectivity measurement and improvement has been designed and implemented. This pattern is printed with an optical stepper on silicon wafers with plating base. These are then processed like an x-ray mask through x-ray absorber definition. Since the absorber is a high-conductivity metal and the substrate is insulating, electrical shorts and opens correspond to extra and missing absorber. This paper describes a series of defect types revealed by these two rather different methodologies: SEM inspection of completed masks using the KLA SEMSpec, as well as the electrically probed test chip pattern. The two methods are compared and contrasted. The main nuisance and genuine defects in our x-ray mask process are catalogued.
Short fibrous supports for preparative chromatographic separations of biomolecules

Abstract The characteristics of short, fibrous supports for chromatographic separations of biomolecules have been studied. A non-porous, silica-based fiber with an anion-exchange functionality was developed, and the performance of this support for protein separations was determined. It was established that the short-fiber column exhibits a low pressure drop, allowing separations to be performed at elevated flow-rates. The dynamic adsorption capacity of the column for three proteins, myoglobin, ovalbumin and bovine serum albumin, have been determined as a function of solution pH and salt concentration. It has been shown that the column can be used to separate mixtures of these proteins at elevated flow-rates.
A weighted Poincaré inequality and removable singularities for harmonic maps

We give a sufficient condition on a closed subset Σ⊂Rn for the weighted Poincare inequality (1.5) below to be valid. As an application, we prove that, for any 2≤p<n and any such closed subset Σ⊂Rn, if u∈C1(Ω ∖ Σ, N) ∩ W1,p (Ω, N) is a stationary p-harmonic map such that ∫Ω|Du|p(x) dx is sufficiently small, then u∈C1(Ω, N). This extends previously known removal singularity theorems for p-harmonic maps.
Characterization and Mitigation of RFI Signals in Radar Depth Sounder Data of Greenland Ice Sheet

Accurate measurements of fast flowing outlet glaciers in Greenland and Antarctica are of vital importance to improve ice-sheet models that predict the ice-sheets' contribution to sea-level rise over the next century. Radars with high sensitivity and advanced processing capabilities are required to sound ice in fast-flowing glaciers. We developed the multichannel coherent radar depth sounder/imager (MCoRDS/I) for ice thickness measurements and 3-D imaging of bedrock over important areas of Greenland and Antarctica. Radio frequency interference (RFI) degrades the sensitivity of the MCoRDS/I system, thus affecting the quality of the data collected. Data from the 2010 Greenland field season exhibited a degraded signal-to-noise ratio (SNR), requiring extensive RFI analysis, investigation, and mitigation for the MCoRDS/I system. Measurements were taken in an electromagnetic interference (EMI) chamber on individual sections of the MCoRDS/I system to isolate the sources of RFI. Then, RFI mitigation techniques were implemented for the offending sections and EMI chamber measurements verified the integrity of the solution prior to the 2011 Greenland deployment. Recorded data from the 2011 Greenland field season also verified that the RFI mitigation resulted in more than 20 dB improvement in the SNR compared to the 2010 Greenland data. The reduction of EMI emissions has also been beneficial to data collection in subsequent deployments.
Mercury BLASTP: Accelerating Protein Sequence Alignment

Large-scale protein sequence comparison is an important but compute-intensive task in molecular biology. BLASTP is the most popular tool for comparative analysis of protein sequences. In recent years, an exponential increase in the size of protein sequence databases has required either exponentially more running time or a cluster of machines to keep pace. To address this problem, we have designed and built a high-performance FPGA-accelerated version of BLASTP, Mercury BLASTP. In this article, we describe the architecture of the portions of the application that are accelerated in the FPGA, and we also describe the integration of these FPGA-accelerated portions with the existing BLASTP software. We have implemented Mercury BLASTP on a commodity workstation with two Xilinx Virtex-II 6000 FPGAs. We show that the new design runs 11--15 times faster than software BLASTP on a modern CPU while delivering close to 99% identical results.
Pressure-induced crossover from good to poor solvent behavior for polyethylene oxide in water.

The application of pressure to solutions of polyethylene oxide in water causes phase separation through spinodal decomposition similar to that observed when the temperature is raised above the lower critical solution temperature. This phase separation pressure is dependent on molecular weight but independent of concentration. Viscosity measurements indicate a continuous decrease in the radius of gyration from good to theta solvent conditions as pressure is increased. This pressure-induced loss of solvent quality is a result of the loss of the ability of water to form hydrogen bonds at high pressure and the resulting changes in hydrophobic interactions.
Severe mitral regurgitation in horses: clinical, echocardiographic and pathological findings

Forty-three horses with mitral regurgitation (MR) and congestive heart failure were examined, using M-mode, 2-dimensional real-time and Doppler echocardiography. There was no breed or sex predisposition when compared to the general hospital population. The mean +/- s.d. age of affected horses was 7.6 +/- 8.1 years. Horses with MR and congestive heart failure had significant increases in mean values for left ventricular chamber size, left atrial size and heart rate and significant decreases in interventricular septal and left ventricular free wall thickness. Significant increases in pulmonary artery diameter were detected compared to aortic diameter. Mean values for fractional shortening were not significantly different from normal. All horses had a Grade 3-6/6 holosystolic or pansystolic murmur with its point of maximal intensity in the mitral to aortic valve area. Atrial fibrillation was found at presentation in 24 horses with MR and congestive heart failure. One horse presented with atrial tachycardia and subsequently developed atrial fibrillation. Seven horses had ventricular premature contractions. Exercise intolerance (n = 34), respiratory signs (n = 31), and fever (n = 21) were the most common presenting signs. Thickening of the left atrioventricular valve leaflets, endocarditis, flail valve leaflets, rupture of a chorda tendineae, and mitral valve prolapse were detected echocardiographically. Doppler echocardiography confirmed the presence of a large systolic regurgitant jet in the left atrium in all horses in which it was used, and in many horses, concurrent tricuspid and pulmonary regurgitation was detected. All horses died or were subjected to euthanasia due to the severity of their MR and/or lack of response to therapy. Post mortem examinations were performed in 35 horses and confirmed the echocardiographic findings. The echocardiographic detection of a flail mitral valve leaflet was significantly associated with the detection of a ruptured chorda tendineae at post mortem examination. There was a significant association between echocardiographic detection of a dilated pulmonary artery and its presence at post mortem examination. M-mode, 2-dimensional real-time, and Doppler echocardiography should be used to accurately characterise the valvular abnormalities and assess the severity of mitral regurgitation. Pulmonary artery dilatation, an echocardiographic indication of severe pulmonary hypertension, should be considered a grave prognostic indicator and may indicate impending pulmonary artery rupture.
On the computation of Kalman gains

Abstract Modern filtering methods often require high order matrix differential equations to be solved. Standard numerical methods are traditionally slow and prone to be unstable. A numerical approach to the problem of computing the Kalman gain matrix is developed which is both numerically efficient and stable. If a piecewise approximation of the Kalman gain matrix is desired, efficiencies of many orders of magnitude can be realized.
New compactifications on Calabi-Yau manifolds

Abstract We find nontrivial configurations for antisymmetric tensor gauge fields on Calabi-Yau manifolds, which have vanishing stress-energy tensor. Our construction is a complex version of the Freund-Rubin ansatz. For certain ten-dimensional models, these configurations provide preferential compactification to anti-de Sitter × Calabi-Yau.
Safety activities in small businesses.

Background Workplace injuries occur at higher rates in smaller firms than in larger firms, and the number of workplace safety activities appear to be inversely associated with those rates. Predictors of safety activities are rarely studied.
College Hopping Exploring the Occurrence, Frequency, and Consequences of Lateral Transfer

Lateral transfer (between community colleges) is second only to upward transfer (to a 4-year institution) among community college students' most common patterns of transfer. Yet, upward transfer is...
Virus growth and cellular energy production: effect of substances chemically related to thyroxin on influenza virus.

ConclusionButyl 3,5-diiodo-4-hydroxy-benzoate, a substance which uncouples phosphorylation from oxidation, has effects very similar to dinitrophenol in inhibiting the growth of influenza virus in tissue cultures and deembryonated eggs.
Responses to Anti-Angiogenic Therapies

Vascular tumors occur in approximately 10% of infants, and range from small cherry-red lesions to large, life-threatening tumors. Although the majority of these tumors involute after several years, there are few therapeutic options and their use is limited by the risk of side-effects. The recent increase in understanding of angiogenesis has led to investigations of new antiangiogenic treatment options using models of vascular tumors in mice. These studies have demonstrated the success of a variety of antiangiogenic approaches, including systemic administration of the antiangiogenic proteins AGM-1470 and angiostatin or of the matrix metalloproteinase inhibitor batimastat, and gene gun therapy with interleukin-12. Although these trials provide further evidence of the role of angiogenesis in the enlargement of these vascular tumors, their potential utility and safety await future trials in patients.
Angiomyolipomas in a case of lymphangiomyomatosis syndrome: relationships to tuberous sclerosis.

In 17 of the 31 reported cases of lymphangiomyoma, cystic pulmonary changes have been noted which are similar to those seen in some patients with tuberous sclerosis. The contention that lymphangiomyoma represents a forme fruste of tuberous sclerosis is based on this observation, and is strengthened by reports of lymphangiomyoma in patients with tuberous sclerosis and cystic pulmonary changes. Further support is presented here where bilateral renal angiomyolipomas, virtually confined to patients with tuberous sclerosis, were discovered in association with extensive lymphangiomyoma and cystic pulmonary changes.
Si Wafer Thinning Techniques Compatible With Epitaxy of CdTe Buffer Layers

Reduction of threading dislocation density is critical for improving the performance of HgCdTe detectors on lattice-mismatched alternative substrates such as Si. CdTe buffer layers grown by molecular beam epitaxy (MBE), with thicknesses on the order of 8 μm to 12 μm, have helped reduce dislocation densities in HgCdTe layers. In this study, the reduction of threading dislocation densities in CdTe buffer layers grown on locally thinned Si substrates was examined. A novel Si back-thinning technique was developed that maintained an epiready front surface and achieved Si thicknesses as low as 1.9 μm. Threading dislocation densities, acquired by defect decoration techniques, were reduced by as much as 60% for CdTe buffer layers grown on these thinned regions when compared with unthinned regions. However, this reduction is inconsistent with prior notions that threading dislocation propagation is dominated by image forces. Instead, the thickness gradient of thinned Si may play a larger role.
Enhanced photoluminescence from poly(phenylene vinylene):dendrimer polyelectrolyte assemblies in solution.

Poly(2,5-methoxy-propyloxy sulfonate phenylene vinylene) (MPS-PPV) and DAB-Am-16, a generation 3.0 polypropylenimine hexadecamine dendrimer (DAB), are shown to form a tunable photoresponsive polyelectrolyte assembly in aqueous solution with an enhanced emission signal of up to 18-times that of MPS-PPV alone.
Depositional framework and hydrocarbon resources of the early Miocene (Fleming) episode, northwest Gulf Coast Basin☆

Abstract The Fleming Group and its basinward equivalents constitute deposits of a major Cenozoic depositional episode of the northern Gulf Coast Basin. The facies complex is bounded above by the Amphistegina B Shale and below by the Anahuac Shale. Initially, early Miocene (Oakville) progradation built across the broad, submerged shelf platform constructed during the earlier Frio depositional episode. At the Frio paleocontinental margin the rate of outbuilding slowed as large-scale growth faulting created a narrow early Miocene expansion zone. The later part of the episode was characterized by a stable to retreating shoreline and consequent aggradational to retrogradational deposition (Lagarto Formation). The lower Miocene depositional framework includes, in South Texas, the Santa Cruz fluvial system and the North Padre delta system. The bedload fluvial complex fed a wave-dominated delta, which constructed a broadly convex deltaic headland across the foundered Frio Norias delta system. Extensive wave reworking and longshore transport of sand and mud nourished a broad barrier/lagoon and strandplain complex that extended along the central and much of the northeastern Texas coast. This well-known Matagorda barrier/strandplain system was bounded updip by a coastal plain traversed by numerous small intrabasinal streams. Near the present Sabine River westernmost deposits of a continental-scale, mixed-load fluvial and equivalent delta system extend beneath the Texas Coastal Plain and shelf from the Miocene depocenter in Louisiana. Here, the initial phase of early Miocene progradation was also complicated by the incision and filling of numerous submarine gorges. Lower Miocene reservoirs have produced nearly 500 million tonnes (4 billion barrels of oil equivalent (BOE)) of hydrocarbons from nine identified plays in the Texas Coastal Plain and shelf. The most prolific play, the salt domes of the Houston Embayment, accounts for nearly all the oil and more than two-thirds of the total production from the sequence. Four offshore plays offer greatest room for discovery of substantial new reserves, primarily of gas. To date, however, the yield per volume of reservoir sandstone for Miocene plays remains low relative to more prolific units, such as the Frio Formation.
Suspension flow and sedimentation in self-affine fractures

The transport and gravitational sedimentation of a particulate suspension in fracture joints with self-affinely rough walls is studied by lattice Boltzmann numerical simulations. We consider either homogeneous or bidisperse distributions of non-Brownian spheres in a Newtonian fluid, driven through a fracture by a pressure gradient, and acted upon by gravity. Most results concern the case of open fractures, in which the two walls of the channel do not approach closely enough to block the flow. We present profiles of particle density and profiles of particle and fluid velocities, along with total flow rates and characterizations of the sediment, for three values of particle concentration and a range of buoyancy and Reynolds numbers, principally in the inertial regime. We systematically study the effects of increasing the pressure gradient and the strength of sedimentation and compare the results to those for channel bounded by flat surfaces. We find that both the flow rate and the average particle velocity for flows through an open fracture, when suitably normalized, depend only on the volume fraction of the particles and the buoyancy number in the steady state regardless of the pressure drop, and observe interesting scaling laws in the large buoyancy number limit. We also investigate the possibility for correlations between the surface morphology of the sediment region and the geometry of the underlying fracture surface in the strong sedimentation limit, but no evidence for correlation is found.
Polymer-induced turbulence modifications in an impinging jet

This effort explores the impact of dilute polymer solutions on the turbulence characteristics in a submerged liquid impinging-jet configuration. Turbulent impinging jets are commonly used in technological applications such as drying, scouring, cooling, or heating due to an enhancement in transport characteristics in the impingement region under certain nozzle-to-wall configurations. Previous efforts have identified significant turbulence modifications in the presence of dilute concentrations of polymer in both bounded and unbounded flows, though the former has received considerably more attention. To this end, particle-image velocimetry measurements were taken for an axisymmetric turbulent impinging jet with a nozzle-to-wall distance H/D = 6.8 and nominal Reynolds number of 26,000. Measurements were performed for both plain water and dilute polymer solutions of polyethylene oxide at concentrations of 50 and 100 ppm. The mean and turbulence characteristics of these three flows are contrasted and it is observed that the two polymer solutions modify both the mean and turbulent characteristics of the jet in all three regions of interest (the free-jet, impingement, and wall-jet regions). Of interest, the 50 ppm case yielded a slight suppression of the turbulence in the free-jet region accompanied by a longer axial length of the potential core compared to the case of plain water. In contrast, the 100 ppm case exhibits clear enhancement of the turbulence in the free-jet region and a shortening of the potential core length. The effect of polymer was opposite in the impingement and wall-jet regions wherein the turbulence was slightly suppressed in the 100 ppm case in a manner consistent with the onset of the Toms effect in this wall-bounded region of the flow.
Heat capacities and absolute entropies of UTi2O6 and CeTi2O6

As part of a larger study of the physical properties of potential ceramic hosts for nuclear wastes, we report the molar heat capacity of brannerite (UTi 2 O 6 ) and its cerium analog (CeTi 2 O 6 ) from 10 to 400 K using an adiabatic calorimeter. At 298.15 K the standard molar heat capacities are (179.46±0.18) J K -1 mol -1 for UTi 2 O 6 and (172.78±0.17) J K -1 mol -1 for CeTi 2 O 6 . Entropies were calculated from smooth fits of the experimental data and were found to be (175.56±0.35) J K -1 mol -1 and (171.63±0.34) J K -1 mol -1 for UTi 2 O 6 and CeTi 2 O 6 , respectively. Using these entropies and enthalpy of formation data reported in the literature, Gibb's free energies of formation from the elements and constituent oxides were calculated. Standard free energies of formation from the elements are (-2814.7±5.6) kJ mol -1 for UTi 2 O 6 and (-2786.3±5.6) kJ mol -1 for CeTi 2 O 6 . The free energy of formation from the oxides at T=298.15 K are (-5.31±0.01) kJ mol -1 and (15.88±0.03) kJ mol -1 for UTi 2 O 6 and CeTi 2 O 6 , respectively.
The effect of protein kinase C and its alpha subtype on human vascular smooth muscle cell proliferation, migration and fibronectin production.

Abstract Background: Vascular smooth muscle cell (SMC) migration, proliferation and extracellular matrix protein production are key steps in the formation of intimal hyperplasia, a process that leads to failure of vascular reconstructions. Protein kinase C (PKC) may be involved in all 3 cellular events. PKC consists of a family of 11 isotypes, 8 of which we have identified in human vascular SMCs. In this study we evaluate the role of PKCα as a second messenger for proliferation, migration and fibronectin production induced by human saphenous vein SMCs. Methods: DNA synthesis was evaluated by using 3 H-thymidine incorporation. Mitogen-activated protein kinase (MAP-K) activation was quantified by Western blotting with an antibody to its phosphorylated substrate, Elk-1. Chemotaxis was evaluated by using a microchemotaxis chamber. SMC fibronectin was measured by Western blotting. For all experiments, PKCα was blocked with a selective inhibitor, Go6976. Results: Go6976, at concentrations that allow selective inhibition of PKCα, inhibited platelet-derived growth factor–stimulated SMC proliferation and MAP-K activation by 30% to 40% and 30% to 60%, respectively. SMC chemotaxis was stimulated approximately 2-fold by the PKCα inhibitor. Neither basal nor transforming growth factor–βI induced fibronectin production was affected by Go6976. Conclusions: Our data suggest that PKCα is a positive mediator of SMC proliferation and MAP-K activity, a negative regulator of migration and has no effect on SMC fibronectin production. These data suggest that modulating activities of specific PKC isotypes might be useful in both the study and control of intimal hyperplasia. (Surgery 2000;128:192-7.)
Toxicology of glucosinolates, related compounds (nitriles, R-goitrin, isothiocyanates) and vitamin U found in cruciferae

The cruciferous glucosinolates (epiprogoitrin, sinigrin and sinalbin), nine of their derivatives (nitriles, isothiocyanates, R-goitrin) and vitamin U were not teratogenic to the rat foetus when administered sc to the dams on days 8 and/or 9 of gestation. However, 1-cyano-3,4-epithiobutane, 3-methylsulphinylpropyl isothiocyanate and allyl isothiocyanate caused embryonal death and decreased foetal weight, whereas five other derivatives only decreased foetal weight. Under identical conditions, the reference teratogen, trypan blue, caused a significant incidence of malformations and resorptions. 3-Methylsulphinylpropyl isothiocyanate was the most toxic compound, followed by allyl isothiocyanate, 1-cyano-3,4-epithiobutane (nephrotoxic) and S-1-cyano-2-hydroxy-3-butene. Some nitriles caused hyperplasia of the thyroid, an effect which often was more pronounced in nonpregnant than in pregnant rats.