cssi/SciSciGPT-SciSciNet huggingface dataset:
CAVASS: a computer assisted visualization and analysis software system - visualization aspects

The Medical Image Processing Group (MIPG) at the University of Pennsylvania has been developing and distributing medical image analysis and visualization software systems for a long period of time. Our most recent system, 3DVIEWNIX, was first released in 1993. Since that time, a number of significant advancements have taken place with regard to computer platforms and operating systems, networking capability, the rise of parallel processing standards, and the development of open source toolkits. The development of CAVASS by our group is the next generation of 3DVIEWNIX. CAVASS will be freely available, open source, and is integrated with toolkits such as ITK and VTK. CAVASS runs on Windows, Unix, and Linux but shares a single code base. Rather than requiring expensive multiprocessor systems, it seamlessly provides for parallel processing via inexpensive COWs (Cluster of Workstations) for more time consuming algorithms. Most importantly, CAVASS is directed at the visualization, processing, and analysis of medical imagery, so support for 3D and higher dimensional medical image data and the efficient implementation of algorithms is given paramount importance. This paper focuses on aspects of visualization. All of the most of the popular modes of visualization including various 2D slice modes, reslicing, MIP, surface rendering, volume rendering, and animation are incorporated into CAVASS.
Environmental dynamism, complexity, and munificence as moderators of strategy-performance relationships

Abstract To assess whether environmental conditions interact with strategies as determinants of performance, analyses were conducted on data describing over 100 large manufacturing firms. Environmental measures obtained from organization theory describe objective conditions in industries delineated at the 4-digit SIC level. Results of hierarchical regression analyses show that environmental dynamism, complexity, and munificence each moderates the form of strategy-performance relationships. These results hold implications for contingency theories of business policy and organization theory, as well as for the practice of management.
Identification of the yeast nuclear gene for the mitochondrial homologue of bacterial ribosomal protein L16

Abstract An open reading frame encoding a member of the L16 family of ribosomal proteins is adjacent to the URA7 gene on the left arm of chromosome II in Saccharomyces cerevisiae. The predicted L16-like polypeptide is basic (pl 11.12), contains 232 amino acids (26.52 kDa) and has 36% amino acid sequence identity to E. coli L16. Immunoblot analysis with polyclonal antibodies to the L16-like polypeptide showed specific cross-reaction with a 22,000 Mr mitochondrial polypeptide that co-sediments with the large subunit of the mitochondrial ribosome in sucrose density gradients. The levels of the L16 mRNA and protein varied in response to carbon source. In [rho degree] cells lacking mitochondrial rRNA, the L16 mRNA accumulated at normal levels, but the protein was barely detectable, indicating RNA-dependent accumulation of the L16 protein. Gene disruption experiments demonstrated that the yeast mitochondrial L16 is an essential ribosomal protein in vivo.
Splash and grab: biomechanics of peridiole ejection and function of the funicular cord in bird's nest fungi.

Abstract The bird's nest fungi (Basidiomycota, Agaricales) package millions of spores into peridioles that are splashed from their basidiomata by the impact of raindrops. In this study we report new information on the discharge mechanism in Crucibulum and Cyathus species revealed with high-speed video. Peridioles were ejected at speeds of 1–5 m per second utilizing less than 2 % of the kinetic energy in falling raindrops. Raindrops that hit the rim of the basidiome were most effective at ejecting peridioles. The mean angle of ejection varied from 67 to 73° and the peridioles travelled over an estimated maximum horizontal distance of 1 m. Each peridiole carried a cord or funiculus that remained in a condensed form during flight. The cord unravelled when its adhesive surface stuck to a surrounding obstacle and acted as a brake that quickly reduced the velocity of the projectile. In nature, this elaborate mechanism tethers peridioles to vegetation in a perfect location for browsing by herbivores.
Comparison of Cl2 and HCl adsorption on Si(100)−(2 × 1)

Abstract The chemisorption and reaction of Cl 2 and HCl on Si (100)−(2 × 1) have been studied using Auger electron spectroscopy, high resolution electron energy loss spectroscopy (HREELS), digital electron-stimulated desorption ion angular distribution (ESDIAD), and temperature programmed desorption. At 100 K, both Cl 2 and HCl dissociatively chemisorb on the dangling bonds of Si(100). At saturation coverage, following an exposure of the Si(100) surface to Cl 2 , the surface concentration of Cl is about one Cl atom per Si atom while HCl can produce a Cl coverage only about one-fourth of that achieved with Cl 2 . This is the first report of a self-site-blocking effect in adsorption on a semiconductor surface. HREELS spectra indicate that both Cl 2 and HCl adsorption at 100 K give a monochloride surface species with an Si-Cl stretching frequency of about 550–600 cm −1 . Digital ESDIAD measurements reveal that the Si-Cl bond angle for the monochloride from both Cl 2 and HCl adsorption is oriented on the vertical plane containing the Si-Si dimer bond and is inclined from the surface normal by 25° ± 4°. The etching products of Si(100) by Cl 2 at elevated temperatures are SiCl 2 at about 800 K and a small amount of SiCl 4 at about 500 K. For HCl, the only observed etching product is SiCl 2 .
Perpendicular upper critical field of thick proximity-coupled multilayers

We consider theoretically the perpendicular upper critical field ${H}_{c2}$(T) versus temperature T for a proximity multilayer structure consisting of two superconductors, a and b, whose critical temperatures obey ${T}_{\mathrm{ca}}$g${T}_{\mathrm{cb}}$ but whose intrinsic upper critical fields obey ${H}_{c2a}$(0)${H}_{c2b}$(0). The latter condition can be satisfied if metal b is sufficiently dirty while metal a is relatively clean. The system's phase boundary, ${H}_{c2}$ versus T, may have a large positive curvature in the temperature domain where ${H}_{c2a}$(T)\ensuremath{\approxeq}${H}_{c2b}$(T). This curvature becomes sharper with increasing thickness.
The electron microscopy of sectioned nerve.

Szent-Gyorgyi and his colleagues at the MBL worked extensively with electron microscopy to better understand the structure of muscle tissue, and did several studies of the nerve tissue in rabbit muscles. This brief report explains a successful technique for preparing and sectioning the delicate nerve tissue.
Female urinary incontinence: pathophysiology, methods of evaluation and role of MR imaging

Urinary incontinence (UI) is one of the most common conditions that cause a significant psychosocial and hygienic problem in an aging female population. In this article we focus on the sphincteric type of stress UI in women, review the anatomy of the urethral sphincter and its support mechanism, and discuss methods of the evaluation of urethral function. Stress UI is the functional consequence of an anatomical abnormality, urethral hypermobility (UH) and intrinsic sphincter deficiency (ISD). Imaging plays an adjunct role to urodynamics in the assessment of women with UI. MR imaging due to its superior soft tissue contrast resolution contributes many findings that are predictive of UH, such as abnormal descent of the bladder neck, disruption of periurethral ligaments and vaginal attachments, and defects within the levator ani muscle. In ISD, MR imaging may show foreshortening or thinning of the sphincter muscle and bladder neck insufficiency manifested by funneling. MR imaging is ideal to evaluate the anatomy of the bladder neck and urethra; functional implications correlate well with functional studies and make MR imaging central to understanding the causes of stress UI and its thorough evaluation.
The Accessory SecA2 System of Mycobacteria Requires ATP Binding and the Canonical SecA1

In bacteria, the majority of exported proteins are transported by the general Sec pathway from their site of synthesis in the cytoplasm across the cytoplasmic membrane. The essential SecA ATPase powers this Sec-mediated export. Mycobacteria possess two nonredundant SecA homologs: SecA1 and SecA2. In pathogenic Mycobacterium tuberculosis and the nonpathogenic model mycobacterium Mycobacterium smegmatis, SecA1 is essential for protein export and is the "housekeeping" SecA, whereas SecA2 is an accessory SecA that exports a specific subset of proteins. In M. tuberculosis the accessory SecA2 pathway plays a role in virulence. In this study, we uncovered basic properties of the mycobacterial SecA2 protein and its pathway for exporting select proteins. By constructing secA2 mutant alleles that encode proteins defective in ATP binding, we showed that ATP binding is required for SecA2 function. SecA2 mutant proteins unable to bind ATP were nonfunctional and dominant negative. By evaluating the subcellular distribution of each SecA, SecA1 was shown to be equally divided between cytosolic and cell envelope fractions, whereas SecA2 was predominantly localized to the cytosol. Finally, we showed that the canonical SecA1 has a role in the process of SecA2-dependent export. The accessory SecA2 export system is important to the physiology and virulence of mycobacteria. These studies help establish the mechanism of this new type of specialized protein export pathway.
Dynamic Terahertz switch based on waveguide-cavity-waveguide (WCW) structure

In this brief, a THz switch consisting of GaAs dielectric slab waveguide with periodic perfect conductor patches on its top and bottom is demonstrated. The performance is based on waveguide-cavity-waveguide structure. By pumping optical signal into the slab waveguide and changing the carrier density of semiconductor directly underneath the patches, and modulating the refractive index of GaAs dielectric it switches between on-state and off-state.
Ascorbate-stimulated active Na+ transport in rabbit ciliary epithelium.

In a physiological medium (134 mM Na+ concentration), unidirectional blood-to-aqueous and aqueous-to-blood Na+ fluxes across the isolated rabbit ciliary epithelium are large, rendering the detection of a net transport difficult. At 134 mM an active component for Na+ may be obscured by diffusional fluxes and a bidirectional Na+-Cl- cotransport. Considering that the active transport saturates at about 30 mM, experiments were performed at this reduced Na concentration to minimize the influence of diffusional pathways. A net blood-to-aqueous Na+ flux that ranged from 0.25 to 0.81 /xeq/hr was obtained. Addition of ascorbic acid to the aqueous side under this condition increased the blood-to-aqueous flux with little effect on the flux in the opposite direction. Ouabain inhibited both the Na+ and ascorbate-stimulated Na+ transport. The increase in blood-to-agueous Na flux by ascorbate was also observed in tissues bathed with [Na+] closer to physiological levels (100 mM). These results indicate that the rabbit ci...
Fog (and infection) creeps in on little cat feet

This is a case report of a patient who developed profound thrombocytopenia during treatment with eptifibatide after PCI of the mid right coronary artery.
The Relation between Parent Rearing Practices and Adolescent Social Anxiety: A Factor Analytic Approach

The purpose of this study was to examine the association between parent rearing practices and adolescent social fears in a community sample (n = 348). Results of an exploratory factor analysis yielded a 3 factor measure of rearing practices, comprised of parental modeling, shame induction, and sociability. Significant differences were found between adolescents with higher levels of social anxiety when compared to adolescents with low levels of social anxiety on levels of parental modeling of social fears and parental communication of shame. However, inconsistent with previous research, no significant differences were found between groups in levels of parent sociability. These findings have the potential to inform the development or refinement of effective prevention and treatment programs for socially anxious adolescents.
Varieties of spiral wave behavior: An experimentalist's approach to the theory of excitable media.

Spiral waves in diverse excitable media exhibit strikingly variegated behavior. Mechanistic interpretations of excitability in laboratory systems are commonly tested by comparing the wavelength, period, and meander patterns of the model’s spiral waves with laboratory observations, but models seem seldom to be rejected by such tests. The reason may be that almost any excitable medium behaves in many respects like almost any other, if its parameters are properly adjusted within a reasonable range. What generalizations can be made about ‘‘excitable media’’ in the absence of more specifications? It would be useful to distinguish such generic features from idiosyncrasies of specific models. The range of behavioral flexibility of the FitzHugh–Nagumo excitable medium is explored by varying two of its parameters and comparing the results with other excitable media to suggest a generic pattern of parameter dependence. The results exhibit the remarkable diversity of rotor behavior in a single model and provide a database for quantitative testing of mathematical generalizations.
Phylogenetic history of social evolution and habitat use in the Aphelocoma jays

Abstract Historical changes in social systems and habitat use of the jays of the genus Aphelocoma were evaluated using parsimony analysis based on an independent phylogenetic estimate. Social evolution has been phylogenetically conservative in this genus, with the origin of cooperative breeding predating the diversification of the genus, and reduction in cooperation occurring subsequently in two independent lineages. Invasion of new habitat types has been less phylogenetically conservative in the genus at the level of analysis in the present study. Although changes in the social system and habitat use appear to be correlated across phylogenetic history, statistical significance of the correlation is difficult to assess. Although these results suggest that comparative studies of social evolution in the New World jays may be biased by non-independence of examples, a potential solution to this problem may lie in analysis of independent evolutionary derivations.
Enantioselective silyl protection of alcohols catalysed by an amino-acid-based small molecule

Reliable, selective and environmentally friendly chemical transformations are crucial to the development of new therapeutics and the design of novel materials. Chiral catalysts that can be easily prepared and used to obtain organic molecules of high enantiomeric purity are critical to modern chemical synthesis. The development of protecting groups that shield reactive functionalities has also proved indispensable in the preparation of complex biologically active molecules. Here we present a chiral catalyst that promotes the enantioselective protection of a secondary alcohol as one of the most commonly used protected forms of an alcohol: a silyl ether. The catalyst is a small, simple molecule that can be prepared in three steps from commercial materials without the need for rigorously controlled conditions. Enantioselective silylations are performed with commercial silyl chlorides and produce yields of up to 96 per cent at an enantiomeric ratio of up to 98:2. Chiral catalysts for selective formation of commonly used protecting groups such as silyl ethers should significantly enhance the ability of chemical synthesis to deliver, in a more practical and efficient manner, important organic molecules.
Effects of stimulus and response contingencies on a surface negative slow potential shift in man

Abstract A slow wave potential (CNV) was recorded extracranially from eleven subjects during the interval between a warning stimulus (flash of light) and a burst of clicks which they terminated by pressing a lever. When subjects were not required to respond to the clicks, no CNV appeared. When they were told to turn off the clicks the CNV increased in amplitude at a rate that depended on individual prior experience with the paired flash-clicks contingency. Omission of clicks with no warning to the subjects resulted in gradual diminution of the CNV; subsequent reinstatement of clicks caused the CNV to increase in amplitude again. A significant negative correlation between size of CNV and reaction time was found over a large group of trials. The relation of the CNV to subjective expectancy and intention to respond was discussed.
Visibility and Soiling: A Comparison of the Effects of Leaded and Unleaded Gasolines

The emissions from a fleet of late-model cars fueled with commercial, high-aromatic, unleaded gasoline caused nearly twice as much atmospheric light extinction as those from a matched fleet fueled with commercial, low-aromatic, leaded gasoline, when both were driven according to a consumer operating cycle in an idle traffic tunnel. The increased extinction and greater soiling potential result mainly from greater light absorption by the air-suspended particles from the unleaded fleet.
Zooplankton community structure, micro-zooplankton grazing impact, and seston energy content in the St. Johns river system, Florida as influenced by the toxic cyanobacterium Cylindrospermopsis raciborskii

Zooplankton can influence the phytoplankton community through preferential grazing. In turn, nuisance cyanobacteria may affect zooplankton community structure by allowing certain species to out-compete others. We examined zooplankton-phytoplankton interactions, micro-zooplankton (< 200 μm) grazing, and biochemical components of the seston in the St. Johns River System (SJR), Florida in the presence and absence of the toxin-producing cyanobacterium Cylindrospermopsis raciborskii. We tested whether this cyanobacterium would cause a decrease in the size structure of the zooplankton community and postulated a resultant decline in the metabolic energy and carbon available to higher consumers (i.e. fish). When numbers of C. raciborskii were low or undetectable, zooplankton were more diverse and were comprised of larger species. Rotifers were the dominant zooplankton, and their numbers relative to other zooplankton increased as C. raciborskii concentrations increased. Micro-zooplankton grazing was higher in times of C. raciborskii abundance, suggesting competitive and predatory exclusion by larger zooplankton in times of higher phytoplankton diversity. Total caloric content of the seston was higher in times of C. raciborskii abundance. However, essential fatty acids and phosphorus may be lacking in the seston, or nutrients may potentially be sequestered by the cyanobacteria and remain as organic matter in the water column. In such cases, higher trophic levels would not be able to obtain optimal energy requirements. Overall, there was a greater impact of micro-grazers on phytoplankton in the presence of C. raciborskii and apparent negative effects on the larger zooplankton species, suggesting a potential for changes in zooplankton and higher trophic level community structure.
Tracking single particle rotation: probing dynamics in four dimensions

Direct visualization and tracking of small particles at high spatial and temporal resolution provides a powerful approach to probing complex dynamics and interactions in chemical and biological processes. Analysis of the rotational dynamics of particles adds a new dimension of information that is otherwise impossible to obtain with conventional 3-D particle tracking. In this review, we survey recent advances in single-particle rotational tracking, with highlights on the rotational tracking of optically anisotropic Janus particles. Strengths and weaknesses of the various particle tracking methods, and their applications are discussed.
Second cluster of strabismus cases after periocular anesthesia without hyaluronidase

We describe a second cluster of cases of iatrogenic strabismus that occurred in clinical practices following cataract surgeries that occurred in 2000 when hyaluronidase was once again unavailable for use in periocular anesthetic regimens. Twelve cases of transient or permanent strabismus were referred by 4 anterior segment surgeons who had no previous cases of postcataract strabismus when performing periocular injections with hyaluronidase. The charts of the patients were reviewed retrospectively. Recurrence of an increase in postoperative strabismus when hyaluronidase became unavailable for a second time supports the concept that this enzyme may be more important than previously suspected in preventing damage to the extraocular muscles after periocular anesthetic injections.
Prospective evaluation of quality of surgery in soft tissue sarcoma

Background Prospective application of the French Sarcoma Group (FSG) method of surgery reporting in soft tissue sarcoma (STS) in a single centre. Methods Patients with primary STS of the extremities or trunk wall consecutively operated at the same institution from January 1996 to December 2002 were evaluated for local recurrence (LR). There were 205 patients, with AJCC/UICC stages III and IV in 51% of cases. Resection types according to FSG were R0 in 147, R1 in 53 and R2 in five cases. Radiotherapy was delivered in 163 patients and chemotherapy in 103. Multivariate analysis was performed. Overall five-year survival was 75%. Median follow-up for surviving patients was 53 months. Results Actuarial five-year LR incidence was 13% in 200 patients with gross resection (R0 + R1), it was 7% in R0 and 30% in R1 patients (p < 0.0001). At univariate analysis, significant prognosticators for LR were age, histotype, tumour invasion, grade and resection type R. At multivariate analysis, resection R1 (relative risk (RR) 4.3, p = 0.001) and grade 3 (RR 3.9, p = 0.013) independently predicted LR. Combining these two variables produced three prognostic groups for LR: group 0 (no factor, n = 70), group 1 (one factor, n = 94) and group 2 (two factors, n = 36) with five-year LR of 4%, 12% and 39%, respectively (p = 6.4 × 10−7). Conclusion This first prospective evaluation of surgery reporting in STS evidences a fourfold, highly discriminating difference in LR between resections R0 and R1.
An automatic bandwidth selector for kernel density estimation

SUMMARY To select a proper bandwidth is a critical step in kernel density estimation. It is well known that the bandwidth selected by cross-validation has a large variability. This difficulty limits the applicability of cross-validation. To reduce the variability, we suggested modifying the sample characteristic function beyond some cut-off frequency in estimating the bias term of the mean integrated squared error. It is proposed to select the cut-off frequency by a generalization of cross-validation. For smooth density functions, the asymptotic distribution of the bandwidth estimator based on the estimated cut-off frequency is obtained. The proposed bandwidth estimator has a relative convergence rate n-, which is much faster than the rate n 1110 for the bandwidth estimate selected by cross-validation. A modification which reduces the chance of selecting a large cut-off frequency is also suggested. In simulation studies, the advantages of the proposed procedures are clearly demonstrated. The procedures are also applied to some data sets.
Asymmetric photoelectron angular distributions from interfering photoionization processes

We have measured asymmetric photoelectron angular distributions for atomic rubidium. Ionization is induced by a one-photon interaction with 280 nm light and by a two-photon interaction with 560 nm light. Interference between the even- and odd-parity free-electron wave functions allows us to control the direction of maximum electron flux by varying the relative phase of the two laser fields.
A guide to short-channel effects in MOSFETs

Short-channel effects form a very important consideration for the performance of very-large-scale integrated circuits built with ultrasmall devices. Definitions of each of the observed short-channel effects in MOSFETs are given by describing their respective phenomenological meanings. The impact of these parameters on the measured I-V curves, as well as the differentiation between long-channel and short-channel behavior from the measured data, are discussed.
Temporal response of plasma erythropoietin to hemorrhage in the ovine fetus.

In previous studies of ovine fetuses, plasma erythropoietin (EPO) concentration increased 10- to 20-fold at 24 hours after hemorrhage and returned toward normal at 48 hours. The present study in fetal sheep was designed to determine in detail the time course of the hemorrhage-induced changes in plasma EPO levels and explore the relationships among EPO concentration, blood oxygen tension, and hematocrit. Chronically catheterized, late gestation ovine feutes (n = 12) were hemorrhaged such that 40% of their blood volume was lost over 2 hours. Plasma EPO concentration, arterial blood gases, pH, and hematocrit were determined at 0, 1, 2, 3, 4, 6, 8, 10, 12, 16, 20, 24, and 36 hours after initiating the hemorrhage. Plasma EPO concentration was determined by radioimmunoassay. Statistical analyses included analysis of variance and least square regression. Mean plasma EPO concentration increased significantly (2.3 ± 0.5 [± standard error of the mean] times basal values) at 4 hours after initiating the hemorrhage, reached a maximum (33.8 ± 12.9 times based values) at 10–16 hours, and decreased to 50% of maximal values at 24 hours after hemorrhage. Hematocrit decreased rapidly during the 12 hours after hemorrhage (P < .0001), whereas arterial blood oxygen tension remained unchanged. The logarithm of EPO concentration was correlated with hematocrit (r = −0.74, P < .0001) but not with arterial blood oxygen tension. Blood EPO concentration began to increase at approximately 3–4 hours after the onset of hemorrhage. Further, EPO concentrations at 24 hours after hemorrhage represented only 50% of the maximal EPO response. The corrlelation between EPO and hematocrit suggests that blood oxygen content rather than oxygen tension is the more important stimulant for augmented EPO production after fetal hemorrhage.
Triply-responsive boronic acid block copolymers: solution self-assembly induced by changes in temperature, pH, or sugar concentration.

Boronic acid-containing block copolymers capable of solution self-assembly into micelles and reverse micelles in response to changes in temperature, pH, and sugar concentration were prepared by reversible addition–fragmentation chain transfer (RAFT) polymerization.
Cholesteatoma in the pediatric patient

Abstract A review of patients with cholesteatoma at the Children's Hospital of Philadelphia from 1981 to 1986 yielded 161 children. Analysis of data from both outpatient and hospital charts revealed a higher incidence of males to females, and the peak incidence of cholesteatoma appeared to be in the 6–10 year age group. Otorrhea was the most common symptom; and on physical examination, the posterior-superior quadrant was most often affected. Both intact canal wall and open cavity procedures were employed depending upon the site and extent of disease. Seventy-six percent of patients underwent an intact canal wall or middle ear procedure initially, with the remainder requiring an open cavity procedure. Recurrent or residual cholesteatoma was found in 32% of 148 patients at the second procedure, and in 7% of 148 patients if a third procedure was necessary. Pre- and post-operative audiometric findings for 91 patients revealed 21% with decreased hearing post-surgically, 50% with no change in hearing and 29% with improved hearing. Post-operative complications were minimal.
A Spatial Characteristic Scheme for Multigroup Discrete Ordinates Electron Energy Deposition in Two Dimensions

Energy deposition calculations are performed due to an incident source of electrons in rectangular slab geometry using the method of discrete ordinates for directions and the multigroup treatment in energy. Using the restricted stopping power formalism to distinguish between large energy loss collisions (catastrophic) and small energy loss collisions (continuous), coupled with a second-order differencing scheme in energy, an improved model of electron energy loss is incorporated in our computational model. Results are presented for isotropic and normal incident sources and compared with available results.
Ecological speciation in a cyclic parthenogen: Sexual capability of experimental hybrids between Daphnia pulex and Daphnia pulicaria

Daphnia pulex and Daphnia pulicaria are cyclically parthenogenetic crustaceans that are distributed widely in North American freshwaters. Hybrids of D. pulex and D. pulicaria are common in the wild, where population genetic analyses have indicated that they are invariably obligately asexual. In this study, we characterize three sexual aspects (sexual egg production, male production, and sexual offspring production) of life history in experimentally bred hybrids to determine the degree of reproductive isolation. In striking contrast to natural hybrids, out of the 53 F1 hybrids we bred, none were obligately asexual. Neither male production nor sexual egg production was limited by hybridization. Our experimental crosses showed that there was little difficulty in generating or backcrossing the F1 generation. In addition, we were able to intercross F1s successfully to produce F2 progeny. We found no evidence that these taxa are reproductively incompatible, despite other reports of apparent adaptive genetic divergence. We conclude that reproductive isolation between D. pulex and D. pulicaria is due to ecological separation, not genetic incompatibility. In light of our results and published data on the biogeography and breeding system of these taxa, neither sterility due to hybridization nor direct inheritance of a sex-limited meiosis suppressor appears to provide a satisfactory explanation for the asexuality of wild hybrids. We propose an alternate hypothesis in which one parental taxon invades a population of the other, the resulting F1 hybrids cross back to a carrier of a meiosis suppressor, and out of the resulting progeny, a high-fitness asexual clone eventually displaces the rest of the population.
A Channel Shortening Approach for Nonlinear Acoustic Echo Cancellation

Acoustic echo cancellers (AECs) are critical for enhancing audio quality in many telecommunication systems. The problem is challenging because the long room impulse response slows the convergence rate and increases the computational complexity of the AEC designs. Nonlinearity in the power amplifier or the loudspeaker further exacerbates the problem. In this paper, we propose a novel AEC algorithm when the loudspeaker-enclosure-microphone system is described by a Hammerstein model. We show that by introducing a shortening filter, the length of the "effective" acoustic echo path is reduced considerably. An adaptive algorithm is developed for the proposed nonlinear AEC structure; its effectiveness is illustrated by computer simulations.
Social knowledge facilitates chunking in infancy.

Two experiments investigated whether infants can use their rich social knowledge to bind representations of individual objects into larger social units, thereby overcoming the three-item limit of working memory. In Experiment 1, 16-month-olds (n = 32) remembered up to four hidden dolls when the dolls had faced and interacted with each other in pairs, but not when they faced and interacted with the infant, suggesting that infants chunked the dolls into social pairs. In Experiment 2 (n = 16), infants failed to remember four dolls when they faced each other without interacting, indicating that interaction between the dolls was necessary to drive chunking. This work bridges a gap between social cognition and memory by demonstrating that infants can use social cues to expand memory.
Effects and etiology of sudden aspen decline in southwestern Colorado, USA

Sudden aspen decline (SAD), affecting Populus tremuloides, was first observed in Colorado in 2004. By 2008 it affected at least 220,000 ha, an estimated 17% of the aspen cover type in the state. In southwestern Colorado, we examined site and stand features in paired healthy and damaged plots to assess the effects of SAD on aspen and to identify factors associated with decline. Root mortality increased significantly with recent crown loss. Consequently, density of regeneration did not increase as the overstory deteriorated, and regeneration that originated since 2002 decreased significantly in stands with moderate to severe SAD. However, mortality of regeneration did not increase with that of the overstory. Remeasurement of a subset of plots after 1–2 yrs showed significant increases in severity. Contrary to expectations, overstory age and diameter were not related to SAD severity as measured by recent crown loss or mortality. Severity of SAD was inversely, but weakly, related to basal area, stem slenderness, and site index, and positively related to upper slope positions. This is consistent with moisture stress as an underlying factor. To test the role of climate as an inciting factor for SAD, a landscape-scale climate model was used to compare moisture status of declining and healthy aspen at the height of the warm drought in water year 2002. Polygons identified as damaged aspen in the 2008 aerial survey had greater moisture deficits than healthy aspen in the 2002 water year. SAD has led to loss of aspen cover in some stands, and is occurring in areas where early loss of aspen due to climate change has been predicted. Further warm, dry growing seasons will likely lead to recurrence of SAD. Published by Elsevier B.V.
Bacterial Oxidation of Dibromomethane and Methyl Bromide in Natural Waters and Enrichment Cultures

Bacterial oxidation of 14CH2Br2 and 14CH3Br was measured in freshwater, estuarine, seawater, and hypersaline-alkaline samples. In general, bacteria from the various sites oxidized similar amounts of 14CH2Br2 and comparatively less 14CH3Br. Bacterial oxidation of 14CH3Br was rapid in freshwater samples compared to bacterial oxidation of 14CH3Br in more saline waters. Freshwater was also the only site in which methyl fluoride-sensitive bacteria (e.g., methanotrophs or nitrifiers) governed brominated methane oxidation. Half-life calculations indicated that bacterial oxidation of CH2Br2 was potentially significant in all of the waters tested. In contrast, only in freshwater was bacterial oxidation of CH3Br as fast as chemical removal. The values calculated for more saline sites suggested that bacterial oxidation of CH3Br was relatively slow compared to chemical and physical loss mechanisms. However, enrichment cultures demonstrated that bacteria in seawater can rapidly oxidize brominated methanes. Two distinct cultures of nonmethanotrophic methylotrophs were recovered; one of these cultures was able to utilize CH2Br2 as a sole carbon source, and the other was able to utilize CH3Br as a sole carbon source.
Absence of exposed bone following dental extraction in beagle dogs treated with 9 months of high-dose zoledronic acid combined with dexamethasone.

Purpose Factors contributing to osteonecrosis of the jaw with anti-remodeling drug treatment are unclear. Epidemiologic and experimental studies have suggested the combination of bisphosphonates and dexamethasone results in osteonecrosis of the jaw more often than either agent alone. The goal of this study was to assess the combination of these 2 drugs in a large animal model previously shown to be susceptible to exposed bone in the oral cavity when treated with bisphosphonates. Materials and Methods Skeletally mature beagle dogs were untreated controls or treated with zoledronic acid (ZOL), dexamethasone (DEX), or ZOL plus DEX. ZOL and DEX were given at doses based on those used in humans. All animals underwent single molar extraction at 7 and 8 months after the start of the study. Extraction sites were obtained at month 9 for assessment of osseous healing using micro–computed tomography and histology. Results No animals were observed to have exposed bone after dental extraction, yet 1 animal treated with ZOL and 1 treated with ZOL plus DEX had severely disrupted extraction sites as viewed by computed tomography and histology. These 2 animals had an intense periosteal reaction that was less obvious but still present in all ZOL-treated animals and absent from untreated animals. There was no significant difference in bone volume within the socket among groups at 4 or 8 weeks after healing, yet the ratio of surface to volume was significantly higher in animals treated with ZOL plus DEX at 8 weeks compared with control animals. Conclusions These findings suggest a more complex pathophysiology to osteonecrosis of the jaw than is implied by previous epidemiologic studies and those in rodents and raise questions about the potential role of DEX in its etiology.
Output controllability of linear discrete-time system

For linear discrete-time systems, the output controllability over a finite time interval is characterized via singular value decomposition. The authors' approach provides a clear insight into non-minimal phase system.
Management and Genetics Research to Improve the Quality of Animal Products: A Beef Perspective

Clearly, the quality of food products from animals is determined by animal management, genetics, and postharvest management and processing. For some products, animal management plays a much greater role than genetics, and the effects of genetics on quality of some products may not be fully known. In general, when management of animals and processing of products are near optimum, genetics may play a very important role in determining ultimate quality. On the other hand, the importance of genetics may be overshadowed when animal management is poor or when postharvest management or processing is inadequate. The broadest definition of quality includes 1) the composition of animal products; 2) visual quality, such as the color of meat, eggs, etc.; 3) sensory properties, such as flavor, texture, tenderness, juiciness; 4) nutritional contribution to the diet, such as protein quality, mineral content, fat composition, etc.; 5) long-term health benefits or detriments, such as impact on bone and muscle development, serum cholesterol, colon health, etc.; and 6) safety from microbiological and
DENDRODENDRITIC INHIBITION IN THE OLFACTORY BULB IS DRIVEN BY NMDA RECEPTORS

At many central excitatory synapses, AMPA receptors relay the electrical signal, whereas activation of NMDA receptors is conditional and serves a modulatory function. We show here quite a different role for NMDA receptors at dendrodendritic synapses between mitral and granule cells in the rat olfactory bulb. In whole-cell patch-clamp recordings in bulb slices, stimulation of mitral cells elicited slowly decaying, GABAA receptor-mediated reciprocal IPSCs that reflected prolonged GABA release from granule cells. Although granule cells had a normal complement of AMPA and NMDA receptors, the IPSC was completely blocked by the NMDA receptor antagonistd,l-AP-5, suggesting that NMDA receptor activation is an absolute requirement for dendrodendritic inhibition. The AMPA receptor antagonist 1,2,3,4-tetrahydro-6-nitro-2,3-dioxobenzo[f]quinoxaline-7-sulfonamide (NBQX) had no effect on IPSCs in the absence of extracellular magnesium but modestly reduced IPSCs in 1 mm magnesium, indicating that the primary effect of the AMPA receptor-mediated depolarization was to facilitate the unblocking of NMDA receptors. Granule cell voltage recordings indicated that effective spike stimulation in granule cells depended on the slow NMDA receptor kinetics. Granule cells also showed a pronounced delay between synaptic stimulation and action potential generation, suggesting that their intrinsic membrane properties underlie the ineffectiveness of brief AMPA receptor-mediated EPSPs. NMDA receptors also seem to have a central role in dendrodendritic inhibition in vivo, because intraperitoneal dizocilpine maleate (MK-801) injection in young adult rats resulted in disinhibition of mitral cells as measured by the generation of c-fos mRNA. The unique dependence of dendrodendritic inhibition on slow EPSPs generated by NMDA receptors suggests that olfactory information processing depends on long-lasting reciprocal and lateral inhibition.
Geochemical Modeling of ZnS in Biofilms: An Example of Ore Depositional Processes

The precipitation of nearly pure, nanocrystalline zinc sulfides (primarily sphalerite and wurtzite) within a biofilm dominated by sulfate-reducing bacteria of the family Desulfobacteriaceae has been observed in the flooded tunnels of an abandoned mine in southwestern Wisconsin. ZnS accumulations are limited to biofilms growing on old mine timbers. ZnS deposits, which comprise about 20 percent of the volume of the biofilm, formed in less than 30 yr from solutions containing only a few milligrams per liter (mg/l) Zn 2+ . A model is proposed wherein sulfate reduction is followed by the formation of aqueous metal-sulfide clusters that aggregate to form 1- to 3-nm‐diameter crystals that are transported and agglomerate to form micron-scale aggregates. Geochemical modeling shows how reduction of sulfate leads to exclusive precipitation of ZnS until most of the Zn 2+ is consumed. The model also predicts a series of discrete metal-sulfide precipitation events that may be used to interpret sulfide mineral paragenesis of low-temperature Cu-Pb-Zn ore deposits. For example, the paragenesis of essentially monomineralic and mixed sulfide layers in Mississippi Valley-type, strataform, and strata-bound Pb-Zn-Cu, and SEDEX deposits can be predicted thermodynamically if the rate of aqueous sulfide generation does not outstrip the flux of metals into the system. Based on the characteristics of ZnS produced by sulfate-reducing bacteria, features of ore deposit minerals consistent with a biogenic origin can be identified. These include microstructures formed by coarsening of nanophase materials, the presence of micron-scale spherical aggregates in organic-rich microenvironments, and spatially heterogeneous patterns of sulfide mineral distribution, consistent with local variations in redox potential and activity of sulfate-reducing bacteria.
Effects of exercise training on the chemical composition of plasma LDL.

The purpose of the present study was to determine the effects of exercise training on the chemical composition of plasma low-density lipoprotein (LDL). Thirteen men (mean age +/- SE, 47.2 +/- 1.5 years) were examined before and after 14 weeks of endurance-oriented exercise training (3 to 4 d/wk, 30 to 45 min/d). Although calculated plasma LDL concentrations remained unaltered (3.49 +/- 0.24 versus 3.65 +/- 0.23 mmol/L), changes in the chemical composition of LDL (increased LDL free cholesterol, cholesterol ester, and phospholipid content) were associated with a reduction in adiposity, umbilical girth, and basal plasma insulin and glucose concentration with training intervention. Increases in LDL molecular weight and particle diameter were associated with a reduction in fat mass, plasma triglyceride concentration, and basal plasma glucose concentration with physical activity. The LDL lipid-to-protein ratio also increased (P < .01) with training by 7%, primarily due to an increase in LDL free cholesterol content (P < .01). These findings indicate the formation of LDL particles that are more cholesterol enriched and protein poor with exercise training, which provides additional evidence for the cardioprotective effect of long-term physical activity.
Statistical Analysis: Theory Versus Practice

In this paper the gap between theory and practice in statistical analysis is investigated, with particular attention given to the Bayesian approach to statistical analysis. The primary concern is with statistical analysis in experimental psychology, although the paper has implications for all areas in which statistical methods are used. Current statistical practice in experimental psychology and various factors contributing to the theory-practice gap in statistical analysis are considered. Finally, some general questions involving scientific reporting and the use of Bayesian procedures in statistical inference are discussed.
Computational simulation of nonlinear L* combustion instability in solid rockets

L* instability in solid rocket motors is numerically modeled using a simplified kinetics combustion model coupled with a simplified L* combustor. A nonlinear combustion model (WSB) is used with low activation energy, bimolecular single-step reaction in the gas phase and high activation energy, zero-order decomposition in the condensed phase. Quasi-steady gas and condensed phase reaction (surface reaction) were assumed. The phenomenological ZeldovichNovozhilov (ZN) approach was used. Classical linear L* analytical results are recovered. Several nonlinear behaviors are predicted computationally, many of which are similar to observed nonlinear L* instability behavior such as extinction, chuffing, limit-cycle (amplitudelimited) oscillations, and frequency shifting. Frequency shifting (or dual frequency oscillation) has been observed experimentally in double base propellant but attributed tentatively to the twostage flame structure of these propellants. In the present model, dual-frequency behavior is manifested without including a two-stage flame structure.
Soft Magnetic Properties of Low Temperature Sintered NiCuZn Ferrite From Powder Prepared by Sol-Gel Method

The fine powder of NiCuZn ferrites was prepared by sol-gel method. The complex permeability spectra are shown for sintered Ni0.75-xZnxCu0.25Fe2O4 specimens with various Zn content x . The electromagnetic properties including initial permeabilityμi, cut-off frequency fr , loss factor tanδ/μi, Curie temperature TC, saturation magnetization Ms and coercive force Hc are given and discussed for these sintered Ni0.75-xZnxCu0.25Fe2O4 specimens. The samples exhibit μi1000 at sintering temperature 880℃, and μi of 610～300 and tanδ/μi of (1.1～4.6)×10-6 at sintering temperature 860～875℃.
Liquid-liquid extraction-gas chromatography mass spectrometry for simultaneous determination of semi-volatile organic compounds in water

Objective To establish a method for simultaneous determination of 25 kinds of semi-volatile organic compounds(SVOCs) including dichlorobenzene,trichlorobenzene,hexachlorobenzene,DDVP,parathion-methyl,malathion,chlorphrifos,parathion,dimethoate,atrazine,carbofuran,chlorothalonil,heptachlor,BHC,DDT,BAP and other substances in water by liquid-liquid extraction and gas chromatography mass spectrometry. Methods The water sample was extracted by dichloromethane,then dehydrated with anhydrous sodium sulfate and concentrated by nitrogen gas,and then analyzed by GC-MS-SIM on DB-5MS capillary column using temperature programming,and quantified by external standard method. Results Under the established experimental conditions, the 25 kinds of SVOCs were separated well, with the detection limit of0. 019 μg /L ~ 0. 64 μg /L,and recovery of 81. 1% ~ 115. 5%. Conclusion The pretreatment of the method was simple,only once extraction is available. This method can be applied to simultaneous determination of 25 SVOCs in water with simple pretreatment,high recoveries and good repeatability.
Synthesis and photophysical properties of expanded dehydrobenzoannulene macrotricycles

A sequential Sonogashira cross-coupling/Pd-mediated oxidative homocoupling strategy affords two expanded dehydrobenzoannulene (DBA) structures containing two [14]DBAs fused to an [18]DBA core. Noticeable differences in the absorption and emission spectra are observed in comparison with a structurally related [18]DBA-centered trefoil containing three fused [14]DBAs.