cssi/SciSciGPT-SciSciNet huggingface dataset:
Electron-diffraction and photoelectron-spectroscopy studies of fullerene and alkali-metal fulleride films

Photoelectron spectroscopy and low-energy electron diffraction (LEED) have been used to examine the electronic structure and crystallinity of thin films of ${\mathit{A}}_{\mathit{X}}$${\mathrm{C}}_{60}$ where A=Na, K, Rb, and Cs and 0\ensuremath{\le}x=6. For undoped ${\mathrm{C}}_{60}$ films, temperature-dependent LEED studies show changes that correspond to the lattice transformation from the simple-cubic to the face-centered-cubic structure. For doped ${\mathrm{C}}_{60}$ films, the LEED results show a decrease in the quality of the LEED pattern upon the nucleation of the body-centered A-${\mathrm{C}}_{60}$ phases. Spectroscopic studies of these fullerides indicate that the effects of electron correlation are always important. In particular, the ${\mathit{A}}_{1}$${\mathrm{C}}_{60}$ phases of Rb and Cs are characterized by an occupied-valence-band feature \ensuremath{\sim}0.5 eV wide centered \ensuremath{\sim}0.25 eV below ${\mathit{E}}_{\mathit{F}}$ that is derived from the lowest unoccupied molecular orbitals (LUMO) of ${\mathrm{C}}_{60}$. The much greater width relative to band calculations is attributed to electron correlation. For these phases, there is also emission at the Fermi level, despite the fact that transport studies indicate insulating character. This implies that the electronic states at ${\mathit{E}}_{\mathit{F}}$ are localized. The ${\mathit{A}}_{3}$${\mathrm{C}}_{60}$ phase of K and Rb exhibit a metallic Fermi-level cutoff. Spectroscopic features 0.3 and 0.7 eV below ${\mathit{E}}_{\mathit{F}}$ are also observed that are not reproduced in one-electron band-structure calculations. The ${\mathit{A}}_{4}$${\mathrm{C}}_{60}$ phases of K, Rb, and Cs all exhibit insulating character with a split LUMO band. All of the ${\mathit{A}}_{6}$${\mathrm{C}}_{60}$ phases are insulators with a filled LUMO band. For Na-${\mathrm{C}}_{60}$, the valence-band spectra show no emission at ${\mathit{E}}_{\mathit{F}}$ for any Na concentration. Finally, photoemission results showed partial occupation of the (LUMO+1)-derived levels, corresponding to ${\mathrm{C}}_{60}^{8\mathrm{\ensuremath{-}}}$ for isolated ${\mathrm{C}}_{60}$ molecules deposited onto multilayers of Na, K, and Rb at 40 K.
PRESSURE-INFILTRATION PROCESSING OF REINFORCED ALUMINUM

Pressure infiltration of liquid metal is one of the most important processing routes for the production of aluminum-matrix composites having a self-supporting reinforcement phase. This article briefly examines the physical phenomena governing infiltration processes, to present practical guidelines derived from their analysis for optimization of the process and the materials produced. Engineering aspects that are pertinent to infiltration techniques, including preform preparation, process configurations, flow control, and innovative processes, are summarized.
Commentary: Psychopharmacological assessment in neurobehavioral teratology

Pharmacological agents can be teratogenic but they can also be valuable tools in behavioral teratology. In this paper we describe some considerations we believe to be important in the use of psychopharmacology to assess the neurological underpinnings of behavioral deficits resulting from teratogenic exposure. Pharmacological challenges of animals exposed in utero to teratogenic agents can increase the sensitivity of behavioral tests and the specificity of the assessment of neural dysfunction. We discuss also some general guidelines for the conduct and interpretation of psychopharmacological experiments with teratogen-exposed animals.
Correlation of platelet taurine levels with thyroid function.

Changes in neurotransmitter or neuromodular activity and levels have been thought to be responsible for some of the behavioral characteristics observed in patients with thyroid disease. To investigate these relationships, taurine, a proposed inhibitory neurotransmitter or modulator, was measured in platelets, which may serve as biochemical model for synaptosomes. Blood of euthyroid, hypothyroid and hyperthyroid patients was collected. Thyroxine was determined by RIA. Platelets were separated using differential centrifugation techniques. The taurine in platelets was separated by ion exchange chromatography and was assayed spectrophotometrically as a product produced by coupling with dinitrofluorobenzene. In hypothyroid, untreated hyperthyroid and euthyroid individuals, taurine/platelet and number of platelets/ml of blood were inversely related. In propranolol-treated hyperthyroid patients, such a relation was not found. Following initial treatment with either antithyroid drugs (i.e. methimazole or propylthiouracil) and/or propranolol, taurine/platelet returned to euthyroid levels while plasma thyroxine levels remained elevated. These data implicate a relationship between taurine in platelets and the thyroid state in man.
Schistosoma mansoni: cercarial degradation of a radioactively labeled collagen gel

Abstract The apparent penetration activity of Schistosoma mansoni cercariae was quantified by means of an in vitro assay with a radioactively labeled Type I collagen gel. Both live cercariae and cercarial preacetabular gland secretions degraded the collagen. The addition of skin lipid or linoleic acid to the gel surface enhanced the degradation by live cercariae.
THIRD-ORDER NONLINEAR OPTICAL PROPERTIES OF METALLO-PHTHALOCYANINES

This paper discusses the third-order nonlinear optical (NLO) properties of metal-free, lead and transition metal phthalocyanines, as well as scandium, yttrium and lanthanide bisphthalocyanines measured by time-resolved degenerate four-wave mixing at 1064 nm. The study focuses on the structure-property relationships and explores the possible mechanisms leading to the enhanced third-order optical nonlinearity measured for this interesting class of NLO materials.
Perceptual foundations in the design of visual displays

This paper discusses how perception affects the relationship between screen design and memory and cognition. The effects of visual grouping, location of material, distinctiveness of elements and arrangement in layouts, and motion are discussed and analyzed. The perceptual and cognitive principles explored can be applied to the design of any visual display. This information provides designers with a perceptual framework for maximizing learning conditions.
Convergence of nonlocal diffusion models on lattices

Abstract In this paper we look at models of nonlocal (or anomalous) diffusion which are defined on subsets of the lattice ϵ Z n , for some ϵ > 0 , and ask if they can be approximated by continuum models. The answer is given by an operator semigroup convergence theorem. As an application, we establish hypotheses under which a discrete model of nonlocal diffusion satisfying an absorbing boundary condition has a continuum limit which is conservative.
Competing promoters in prokaryotic transcription.

Abstract Two (or more) bacterial promoters are often found in close proximity, and may compete for the binding of RNA polymerase. These competing promoters have interesting characteristics in vitro and analysis of the competition should be valuable to kinetic studies of more complex transcription systems.
Metropolitan patenting, inventor agglomeration and social networks: A tale of two effects

Abstract We investigate the separate effects on metropolitan patenting of inventor agglomeration and the structure of social networks linking inventors within and across metropolitan areas in the United States between 1977 and 2002. Using patent data we have been able to assign a metropolitan location to individual inventors, link inventors who have co-authored patents, and characterize the structural features of the networks linking inventors. Our main question concerns the relative importance of salient features of the social networks linking inventors on metropolitan patenting productivity. We find that agglomerative features of metropolitan areas are more important determinants of metropolitan patenting productivity than structural feature of the inventive networks. While the aggregation of isolated inventors correlates positively with patenting productivity, density of connections correlates negatively.
Asymptotically free quantum gravity and black holes

Abstract A renormalizable, asymptotically free theory of quantum gravity is proposed and shown to exhibit a unitary S -matrix via the Lee-Wick construction. The consequences of the theory for black holes are discussed. Asymptotic freedom argues against any singularity in the final state of an evaporating quantum black hole.
A Kinetic Model for Boron and Phosphorus Doping in Silicon Epitaxy by CVD

A kinetic model based on (i) the collision theory of heterogeneous unimolecular elementary reactions, (ii) statistical physics, and (iii) the concept of competitive adsorption is proposed for both p-type and n-type doping in silicon epitaxy by chemical vapor deposition (CVD). It takes into account both homogeneous and heterogeneous reactions, which involve the precursors (silane and dopant precursor) and their homogeneous decomposition products, and four types of surface sites, hydrogen-terminated silicon and dopant sites and hydrogen-free silicon and dopant sites. The model provides analytical equations to describe dopant concentration and silicon growth rate as a function of deposition conditions, including temperature and partial pressure of dopant precursor. At low temperatures, the enhancement in growth rate with diborane is attributed to enhanced hydrogen desorption from boron sites, which act as catalytic sites for silicon growth. The relationship between boron concentration and diborane partial pressure is more complicated than a simple linear one. The suppression in growth rate with phosphine is modeled by a blocking factor that represents the extent of the "poisoning" effect of phosphorous on the surface. Homogeneous decomposition of phosphine accounts for phosphorous doping behavior at high phosphine partial pressures. The model agrees well with the experimental data.
Debate coaches: Why they quit

This article discusses the reasons 1107 college speech department heads, forensic directors, and NFL chapter sponsors believe debate coaches quit coaching.
A new view of V(D)J recombination

The DNA rearrangement that assembles antibody and T cell receptor genes is beginning to be understood. New work shows that the first step is a site-specific cleavage which can be performed by purified RAG1 and RAG2 proteins. The later steps largely overlap with the repair of radiation-induced DNA double-strand breaks, as indicated by the identity of several newly cloned factors. These developments open the way for a thorough biochemical study of V(D)J recombination.
Comments on Vivian Cook's “Going Beyond the Native Speaker in Language Teaching”; How Nonnative Speakers as Teachers Fit Into the Equation

* Vivian Cook's article, "Going Beyond the Native Speaker in Language Teaching" (Vol. 33, No. 2, Summer 1999), draws attention to an issue that has finally gained the notice of the TESOL field in the past few years: the emphasis on the native speaker (NS) model in language teaching and whether it is time to admit the validity and even the necessity of nonnative models for language learning and teaching. Cook states that "language teaching would benefit by paying attention to the L2 user rather than concentrating primarily on the native speaker" (p. 185) and gives suggestions for how this can be done. He emphasizes the useful notion of the multicompetent language user and distinguishes between the language learner and the language user. This perspective is refreshing and absolutely necessary given the increased use of English among nonnative speakers (NNSs) both in English-speaking countries and in places where English is used as a lingua franca among speakers of various languages and cultural backgrounds. One perspective that is underemphasized in Cook's article, however, is that of nonnative-English-speaking teachers, both as working teachers and as prospective teachers. The NNS as teacher can be a valuable example of skilled L2 use, not just because such a teacher is "fallible" or "presents a more achievable model" (p. 200) but because of the knowledge and experience that teacher can share with learners. Reconsidering the NS in L2 teaching requires examining how nonnative teachers are viewed during their training and afterward in classrooms and among their peers. Recent articles and books on the subject of the NNS as English ong Fillmore, L. ( 991). Whe learning a second language means losing the first. arly Childhood Research Quarterly, 6, 323-346. ntella, A. C. (1997). Growing up bilingual: Puerto Rican children in New York. Malden,
Modeling and Response Analysis of Piezoelectric Flag in Wind Flow

Within the past decade, research in the piezoelectric energy harvesting field has grown significantly concerning material selection, device configurations, and actuation methods. Oscillating cantilevered piezoelectric energy harvesters are one of the more common designs. The flag is modeled as a cantilevered Euler-Bernoulli beam with a low modulus of elasticity, and the representative equation for this is broadly accepted. The wind pressure is modeled by a method that is apparently well accepted in the aerospace field. Among other modeling assumptions, the partial differential equation is considered separable. Once separated, the spatial equation is adjusted using an auxiliary function in order to determine the mode shapes. With the mode shapes characterized, the time function is rendered, which can yield representations for either a damped or undamped system. Individually, these time functions are combined with the adjusted spatial function using the Galerkin method. Plotted results represent the periodic, two-dimensional system response over time.Copyright © 2013 by ASME
Pharmacokinetics and safety of a unilamellar liposomal formulation of amphotericin B (AmBisome) in rabbits

Abstract A unilamellar liposomal formulation of amphotericin B (LAmB) known as AmBisome was safely administered intravenously to 20 rabbits at 0.5, 1.0, 2.5, 5, or 10 mg/kg of body weight, whereas of 12 rabbits given desoxycholate amphotericin B (DAmB) intravenously at 0.5, 1.0, or 1.5 mg/kg, 2 died of acute cardiac toxicity when DAmB was administered at the highest dose. Single-dose LAmB (1 mg/kg) achieved a maximum concentration in serum (Cmax) of 26 +/- 2.4 micrograms/ml and an area under the curve to infinity (AUC0-infinity) of 60 +/- 16 micrograms.h/ml, while single-dose DAmB (1.0 mg/kg), by comparison, achieved a lower Cmax (4.7 +/- 0.2 micrograms/ml; P = 0.001) and a lower AUC0-infinity (30.6 +/- 2.2 micrograms.h/ml; P = 0.07). Following administration of a single dose of LAmB (10 mg/kg), a disproportionately higher Cmax (287 +/- 14 micrograms/ml) and AUC0-infinity (2,223 +/- 246 micrograms.h/ml) occurred, indicating saturable elimination. After chronic dosing (n = 4) with LAmB at 5.0 mg/kg/day for 28 days or DAmB at 1.0 mg/kg/day for 28 days, LAmB achieved daily peak levels of 122.8 +/- 5.8 micrograms/ml and trough levels of 34.9 +/- 1.8 micrograms/ml, while DAmB reached a peak of only 1.76 +/- 0.11 microgram/ml and a trough of 0.46 +/- 0.04 microgram/ml (P < or = 0.001). Significant accumulations of amphotericin B into reticuloendothelial organs were observed, with 239 +/- 39 micrograms/g found in the liver after chronic LAmB dosing (5 mg/kg/day), which was seven times higher than the 33 +/- 6 micrograms/g after DAmB dosing (1 mg/kg/day) (P = 0.002). Accumulation in kidneys, however, remained 14-fold lower (P =0.04) following LAmB dosing (0.87 +/- 0.61 microgram/g) than after DAmB dosing (12.7 +/- 4.6 microgram/g). Nephrotoxicity occurred in only one of four LAmB treated animals, while it occurred in all four chronically DAmB-treated animals: mild hepatozicity with transaminase elevations was seen in one LAmB-treated rabbit. We conclude that LAmB safely achieved higher Cmax(s) and AUC0-infinity(s) and demonstrated saturable, nonlinear elimination from plasma via reticuloendothelial organ uptake. Take reduced nephrotoxicity of LAmB correlated with diminished levels of amphotericin B in the kidneys.
A Vulnerable World: Heidegger on Humans and Finitude

The notion of vulnerability comes from the Late Latin vulnerabilis, derived from vulnerare “to wound,” which comes from vulner-, vulnus “wound.” As the Merriam-Webster dictionary suggests, it is probably akin to Latin vellere, “to pluck,” and Greek oulē, “wound.” The Latin noun vulnus refers primarily to bodily wounds and moral hurts or emotional damages, but it also signifies a blow, a cut, or a bite, as well as an arrow or a projectile. Standard definitions of “vulnerable” list two main meanings: 1: capable of being physically or emotionally wounded; 2: open to attack or damage: assailable (vulnerable to criticism). Even this cursory look at the etymology of the term makes clear that the thinking of vulnerability pivots on the understanding of how that which is vulnerable comes to be constituted: in its existence, identity, or self and thus also in its proper boundaries. Before one can speak of vulnerability, there needs to be a “something,” an “it”—a being or an entity—that is or can become vulnerable, with its boundaries compromised, violated, even destroyed. Vulnerability is concerned precisely with the permeability of such boundaries, their susceptibility to danger and violation. It is clear then that vulnerability suggests primarily a lack or absence, a degree of exposure that compromises the presumed integrity of whatever has become vulnerable. In this specific sense, vulnerability has a negative tenor, indicating a measure of impairment or damage to integrity—integrity that is taken as the initial or original indicator of the proper state in which a being would be in-vulnerable. This would mean that the notion of vulnerability is subtended by the idea of integrity: the condition of being whole, entire, or undiminished, taken as the proper state of existence of what, in principle, should be and remain within its assumed boundaries, proper or integral to itself, and thus invulnerable. I want to examine to what extent the very notion of vulnus, and thus of various forms of vulnerability, presupposes the idea of a being or an entity that becomes vulnerable precisely because it has a priori been conceived as existing and thus contained, whole, or undiminished within its proper “boundaries”: both bodily and moral, or rational.
Naturalistic experience transforms sensory maps in the adult cortex of caged animals

Much of what is known about the functional organization and plasticity of adult sensory cortex is derived from animals housed in standard laboratory cages. Here we report that the transfer of adult rats reared in standard laboratory cages to a naturalistic habitat modifies the functional and morphological organization of the facial whisker representation in the somatosensory 'barrel' cortex. Cortical whisker representations, visualized with repeated intrinsic signal optical imaging in the same animals, contracted by 46% after four to six weeks of exposure to the naturalistic habitat. Acute, multi-site extracellular recordings demonstrated suppressed evoked neuronal responses and smaller, sharper constituent receptive fields in the upper cortical layers (II/III), but not in the thalamic recipient layer (IV), of rats with naturalistic experience. Morphological plasticity of the layer IV barrel field was observed, but on a substantially smaller scale than the functional plasticity. Thus, transferring animals to an environment that promotes the expression of natural, innate behaviours induces a large-scale functional refinement of cortical sensory maps.
Moving Beyond Traditional Measurement of Mortality after Injury: Evaluation of Risks for Late Death

Background The purpose of this study was to evaluate long-term mortality after trauma, and to determine risk factors and possible disparities related to mortality after hospital discharge. Study Design Level I trauma center registry data from a 6-year period (2000 through 2005) were linked to patient electronic medical records, the National Death Index with cause of death codes, and census data using geographic information science (GIS) methodologies. Census data provided supplemental demographic and socioeconomic information from patient neighborhoods. Results The hospital mortality rate for 15,285 patients was 3.3%, and mortality after discharge was 4.8%. Overall mortality for the study period was 8.1% (average follow-up, 2.8 years, 1-year mortality, 5.4%). Mortality after discharge was related to the initial injury in 33%, possibly related in 23%, and unrelated in 44% of patients. Logistic regression analysis demonstrated that independent predictors of hospital mortality were age, Injury Severity Score, gunshot injury, significant head injury, fall, and spinal cord injury. In contrast, independent risk factors for mortality after discharge were age, hospital length of stay, discharge from the hospital to a locale other than home, and the presence of spinal cord injury. Intoxication at hospital admission and injury due to a gunshot wound or motor vehicle collision were protective for late mortality. Bivariate analysis of census data demonstrated that lower socioeconomic status was associated with improved hospital survival, and non-native status was associated with mortality after discharge. Conclusions There is significant mortality attributable to trauma for up to 1 year after hospital discharge. These findings suggest that mortality after trauma needs to be measured beyond hospital discharge in order to assess the complete impact of injury.
Detection of p16 gene deletions in gliomas : A comparison of fluorescence in situ hybridization (FISH) versus quantitative PCR

The p16 protein plays a key role in cell cycle control by preventing CDK4 from inactivating the retinoblastoma protein (pRb). The corresponding tumor suppressor gene (p16/MTS1/CDKN2) has recently been implicated in malignant progression of astrocytomas and could potentially serve as an important marker for patient prognosis and for guiding specific therapeutic strategies. We have undertaken a study to evaluate 2 methods of detecting p16 deletion. Thirty diffuse gliomas were analyzed for p16 gene dosage. Dual color fluorescence in situ hybridization (FISH) was performed on cytologic preparations using paired centromeric (CEN) and locus-specific probes for CEN9/p16, CEN8/RB, and CEN12/CDK4. Quantitative PCR was performed using primers for p16, MTAP, and reference genes. Eleven cases were also studied using comparative genomic hybridization (CGH). Abnormalities of the p16-CDK4-RB pathway were identified in 21 (70%) cases by FISH and/or PCR. These included 15 (50%) with p16 deletion, 9 of which were detected by both techniques, 3 by FISH alone, and 3 by PCR alone (concordance rate = 81%). FISH analysis further revealed tetraploidy/aneuploidy in 14 (47%), RB deletion in 11 (37%) and CDK4 amplification in 1 (3.3%). There were 94% and 100% concordance rates between CGH and FISH or PCR, respectively. Quantitative PCR was noninformative in 4 cases. Although FISH and quantitative PCR are both reliable techniques, each has limitations. PCR is likely to miss p16 deletions when there is significant normal cell contamination or clonal heterogeneity, whereas the p16 YAC probe used for FISH analysis may miss small deletions. Replacement of the latter with a cosmid probe may improve the sensitivity of FISH in future experiments.
Excitonic enhancement of the Fermi-edge singularity in the optical spectra of doped semiconductors.

Low-temperature optical-absorption and -emission spectra are calculated for n-type doped semiconductors in which the Fermi level is nearly degenerate with the exciton of a higher conduction band. It is shown that in such a system the Fermi-edge singularity can be strongly enhanced by the hybridization with the excitonic resonance. In fact, due to this enhancement the Fermi-edge singularity, which is usually only observed in absorption, also becomes visible in the emission spectrum, in accordance with recent experimental findings.
Financial Intermediaries as Markets for Firm Assets

This article proposes a theory of financial intermediation based on intermediaries’ role in the reallocation of assets of distressed firms. The article suggests that intermediaries aggregate information on firms in credit relationships and use this information to facilitate asset reallocation across firms. However, this role of intermediaries hinges on debt contracts that grant lenders the right to foreclose assets of distressed borrowers and, hence, exclude the most productive asset users from the resale market. We characterise conditions under which intermediaries arise and under which their role in the credit market enhances their role as markets for firm assets.
The effect of reagent rotation on reactivity: Classical decoupling approximations

Abstract We have investigated the accuracy of the classical centrifugal sudden (CCS) and the classical infinite order sudden (CIOS) approximations for model A+BC(j) reactions. The CCS is usually in excellent qualitative agreement with exact data. The CIOS performs well only under extreme “sudden” conditions. Use of these decoupling approximations allows an unambiguous definition of the “orientational” and the “energetic” contributions to the rotational excitation function.
14-3-3 Proteins Mediate an Essential Anti-apoptotic Signal

The 14-3-3 proteins are a family of highly conserved eukaryotic regulatory molecules that play important roles in many biological processes including cell cycle control and regulation of cell death. They are able to carry out these effects through binding and modulating the activity of a host of signaling proteins. The ability of 14-3-3 to inhibit Bad and other proapoptotic proteins argues that 14-3-3 can support cell survival. To examine this issue in a global sense, a specific inhibitor of 14-3-3/ligand interactions, difopein, was used. Difopein expression led to induction of apoptosis. Studies using various components of survival and death signaling pathways were consistent with a vital role for 14-3-3/ligand interactions in signal transduction from upstream pro-survival kinases to the core apoptotic machinery. Because these kinases often become activated during oncogenesis, the effect of difopein on cell death induced by antineoplastic drugs was examined. It was found that difopein enhances the ability of cisplatin to kill cells. These data support the model that 14-3-3, through binding to Bad and other ligands, is critical for cell survival signaling. Inhibition of 14-3-3 may represent a useful therapeutic target for treatment of cancer and other diseases involving inappropriate cell survival.
β-Lactams as building blocks in the synthesis of macrocyclic spermine and spermidine alkaloids

Abstract Syntheses of the macrocyclic spermidine alkaloids (±)-celacinnine ( 1 ) and (±)-dihydroperiphylline ( 2 ) as well as the related spermine alkaloid (±)-verbascenine ( 3 ) were accomplished by means of sequential ring expansions of smaller lactam rings. Three ring expansion methods were employed: (1) transamidation of N -(aminoalkyl)lactams, (2) β-lactam-lactim ether condensation followed by reductive cleavage of the bicyclic 4-oxotetrahydropyrimidine product with NaBH 3 CN/AcOH and (3) bicyclic acyl hydrazine formation followed by N–N bond cleavage with Na/NH 3 . Each synthesis features ring expansion of a 4-phenylazetidin-2-one intermediate that undergoes transamidative ring expansion or lactim ether condensation.
Pattern formation inDrosophila melanogaster: The effects of mutations on polarity in the developing leg.

The effects of the mutations eyeless dominant (eyD) and shibire (shi) on bristle pattern in the legs ofDrosophila melanogaster were examined. Both mutations cause gaps in the intersegmental membranes which separate leg segments and often alter the position of these membranes. It was observed that pattern disturbances including reversed bristle polarity and duplication of structures such as sex combs and transverse rows were associated with defects in the intersegmental membranes. The alterations in bristle polarity and most of the duplication of structures could be accounted for by a segmentally reiterated gradient in the legs which controls bristle polarity and which requires the integrity of the intersegmental membrane. A computer simulation of this gradient model was devised which accounted for the observed results. The possible role of cell death as a cause of the gaps in the intersegmental membrane and of some of the pattern disturbances was examined.
Depression by calcium of spontaneous transmitter release at the mammalian neuromuscular junction

The effect of extracellular calcium on the frequency of miniature end-plate potentials (MEPPs) at the rat neuromuscular junction was studied using 5 different concentrations of K+ (2.5, 5, 10, 15 and 20 mM). At low and normal levels of K+ (2.5 and 5 mM), incremental increase of Ca2+ concentration (0.1, 0.5, 1, 2, 3, 4, 7 and 10 mM) produced a slight monotonic increase in MEPP frequency. In 10 or 15 mM-K+, the frequency of MEPPs increased monotonically as Ca2+ concentration was raised from 0.1 to 4 mM, but was unaltered or declinedslightly with further increase of Ca2+ concentration. In 20 mM-K+, the frequency reached its maximum at 1 mM-Ca2+ and progressively decreased as Ca2+ concentration was increased to 10 mM. Thus, the relationship between Ca2+ concentration and MEPP frequency was monotonic at the lower levels of K+ but became distinctly non-monoonic with increased K+. This non-monotonic effect of Ca2+ is consistent with the hypothesis that there are two opposing effects of increasing Ca2+ concentration on transmitter release: (i) an increased Nernst equilibrium potential for Ca2+ which causes an increase in Ca2+ influx and a consequent rise in MEPP frequency and (ii) increased electrostatic screening of negative surface charges near Ca2+ channels which produces an effective hyperpolarization across the channels and a consequent decrease in Ca2+ influx.
Imaging the Magnetic Field in the Atmosphere of TX Camelopardalis

Recent advances in very long baseline interferometry (VLBI) allow full interferometric imaging, in both linear and circular polarization, of the 43 GHz SiO maser emission in the immediate circumstellar environment of late-type stars. The SiO masers act as unique probes of the magnetic field in the near circumstellar environment and provide information on the stellar field morphology of distant stars at unprecedented angular resolution. This technique allows direct imaging of the magnetic field in the extended atmospheres of distant stars. We report on such observations of the ν = 1, J = 1-0 SiO maser emission toward the Mira variable TX Cam, finding a mean magnetic field strength of B sec θ ~ 5-10 G, where θ is the angle between the line of sight and the magnetic field, as well as evidence for an orderly field topology over significant portions of the maser shell. The implied field geometry and implications for possible mass-loss mechanisms are discussed.
Relationship of senescence of corn (Zea mays L.) stalk pith, cob parenchyma and first developed leaf tissues to RNA content and synthesis

Abstract In stalk parenchyma tissue of WF9 × 38-11 single cross corn ( Zea mays L.). there was a per cell increase in RNA synthesis and a slight increase in total RNA as cells became older. In cob parenchyma tissue of WF9 × 38-11 single cross corn, oth total RNA content and RNA synthesis per cell decreased with the age of cells. In first developed leaf tissue of FR43 × FR14A single cross corn, RNA synthesis increased steadily but only slightly over its life span. The pattern of RNA synthesis and destruction in senescing leaf tissue of seedlings and two sources of parenchyma tissue of maturing plants appeared to differ.
Modeling adaptive optics for the segmented aperture of the GMT

We present expected performance for the Giant Magellan Telescope (GMT) adaptive optics system. Using a custom adaptive optics modeling code developed at the University of Arizona, we are able to simulate the various aspects of atmospheric turbulence, wavefront sensing, and adaptive correction for the specific geometry of the GMT AO system. This allows us to explore the design space of the GMT and determine the performance of the system for various adaptive optics modes, including Ground-Layer AO. We present results showing the effect of the segmented aperture on AO performance, and discuss strategies for sensing and correction with the GMT aperture.
Influence of native disulfide bonds of globular proteins on their retention behavior on reverse phase supports

The reduction of the disulfide bonds of globular proteins, for example, those of lysozyme or ribonuclease-A, results in an increase in the hydrodynamic volume of the polypeptide chain. This is reflected in an earlier elution of the reduced protein on gel filtration compared to that of the native disulfide-bonded form. The reduction of the four disulfide bonds of ribonuclease-A increased its retention time on reverse phase support, suggesting an increase in the “apparent hydrophobicity” of the protein molecule on reduction. Performic acid-oxidized ribonuclease-A eluted ahead of native disulfide-bonded ribonuclease on RP HPLC, suggesting a decrease in the hydrophobicity of the molecule. However, the hydrodynamic volume of performic acid-oxidized ribonuclease-A is similar to that of reduced protein as reflected in its gel filtration behavior. Thus, the increased retention of the reduced protein compared to that of native disulfide-bonded protein is not related to the increased hydrodynamic volume, and is a reflection of the stronger interaction of reduced protein with the reverse phase support. Reoxidation of the reduced ribonuclease-A regenerated the original chromatographic behavior of the protein on the reverse phase support. Similar results were also obtained with hen egg white lysozyme. The results of the present study are interpreted as indicating that the native disulfide bonds of a globular protein restrict the exposure of the hydrophobic amino acid residues of the polypeptide chain with a consequent lower retention on the reverse phase support compared to its reduced form.
Sponsored Search Auctions: Recent Advances and Future Directions

Sponsored search has been proven to be a successful business model, and sponsored search auctions have become a hot research direction. There have been many exciting advances in this field, especially in recent years, while at the same time, there are also many open problems waiting for us to resolve. In this article, we provide a comprehensive review of sponsored search auctions in hopes of helping both industry practitioners and academic researchers to become familiar with this field, to know the state of the art, and to identify future research topics. Specifically, we organize the article into two parts. In the first part, we review research works on sponsored search auctions with basic settings, where fully rational advertisers without budget constraints, preknown click-through rates (CTRs) without interdependence, and exact match between queries and keywords are assumed. Under these assumptions, we first introduce the generalized second price (GSP) auction, which is the most popularly used auction mechanism in the industry. Then we give the definitions of several well-studied equilibria and review the latest results on GSP’s efficiency and revenue in these equilibria. In the second part, we introduce some advanced topics on sponsored search auctions. In these advanced topics, one or more assumptions made in the basic settings are relaxed. For example, the CTR of an ad could be unknown and dependent on other ads; keywords could be broadly matched to queries before auctions are executed; and advertisers are not necessarily fully rational, could have budget constraints, and may prefer rich bidding languages. Given that the research on these advanced topics is still immature, in each section of the second part, we provide our opinions on how to make further advances, in addition to describing what has been done by researchers in the corresponding direction.
Microbial dealkylation of trifluralin in pure culture

Mixed populations of soil microorganisms were enriched in the presence of trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) and 180 pure strains were subsequently isolated. About a third were able to liberate 1.5–6% 14CO2 from 0.15 mM [propyl-1-14C]trifluralin after growing for 21 days on a complex medium. One strain, identified as a Candida sp., showed a 14CO2 evolution of 11%. The amount of liberated 14CO2 could not be enhanced by adding small concentrations (<3%) of solvents to the culture, by varying the concentration of trifluralin, or by varying the composition of the complex medium. The Candida sp. was unable to cleave the aromatic ring of trifluralin or to use trifluralin as a sole source of carbon or nitrogen. Only traces (< 1%) of dealkylated trifluralin were accumulated in the culture.
Are young people with an elevated carotid intima-media thickness at increased risk of vascular events?

Are young people with an elevated carotid intima–media thickness at increased risk of vascular events?
Role of oxide ionicity in electronic screening at oxide/metal interfaces

Metal and oxygen core-level Auger and photoemission spectra have been measured for ultrathin epitaxial films of $\ensuremath{\alpha}\ensuremath{-}{\mathrm{Cr}}_{2}{\mathrm{O}}_{3}$ and $\ensuremath{\alpha}\ensuremath{-}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3}$ on Pt(111). The binding-energy shifts of monolayer films relative to thicker films suggest a much smaller extent of screening by the metal substrate than that reported earlier for MgO/ Ag(001) [S. Altieri, L. H. Tjeng, F. C. Voogt, T. Hibma, and G. A. Sawatsky, Phys. Rev. B 59, R2517 (1999)]. This finding suggests that the higher degree of bond covalency in $\ensuremath{\alpha}\ensuremath{-}{\mathrm{Cr}}_{2}{\mathrm{O}}_{3}$ and $\ensuremath{\alpha}\ensuremath{-}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3}$ relative to MgO results in more effective intrinsic screening of charge-transfer processes, rendering the metal much less effective for extrinsic screening. As a result, the metal is expected to have a negligible effect on the optical, electronic, and magnetic properties of the oxide.
C1q nephropathy and minimal change nephrotic syndrome.

C1q nephropathy (C1qN) is an uncommon disorder seen in children and adults with nephrotic syndrome and non-specific urinary findings. It has been described with minimal change nephrotic syndrome (MCNS), focal segmental glomerulonephritis and isolated mesangial proliferative glomerulonephritis. We describe nine children with MCNS and mesangial C1q deposition. These children had a median age of 2.7 years at diagnosis (range 1.3–15 years), 56% were male and 78% were Hispanic. We compared these children to concurrent patients with nephrotic syndrome and biopsy-proven MCNS. We found that the C1qN patients were more likely than MCNS children to require chronic immunosuppression with calcineurin inhibitors or mycophenolate mofetil to maintain remission. However, all children were able to achieve and sustain clinical remission of nephrotic syndrome. Children with C1qN and minimal change histology have an increased frequency of frequently relapsing and steroid-unresponsive disease, but they can attain prolonged remission and stable renal function with calcineurin inhibitor or mycophenolate mofetil therapy.
Geostationary satellites reveal motions of ocean surface fronts

A new method of locating and viewing ocean surface fronts is demonstrated in animations of daily composites of hourly sea surface temperatures derived from the NOAA Geostationary Operational Environmental Satellites (GOES). The animation of the satellite images allows the human eye to separate the faster-moving residual clouds from slower-moving ocean currents, fronts and eddies. The animations produce the sense of an ocean in motion that is not apparent in individual satellite images. Three years of GOES animations of sea surface temperatures of the Atlantic and Pacific Oceans are used to illustrate the westward propagation of Pacific Tropical Instability Waves (TIW) during La Nina, the seaward deflection of the Gulf Stream at the Charleston Bump, a time series of the Loop Current and separation of six warm core eddies in the Gulf of Mexico, and the cyclonic eddies and westward-moving meridional fronts near the Hawaiian Islands.
High‐resolution ultrasound analysis of subsynovial connective tissue in human cadaver carpal tunnel

The carpal tunnel contains the median nerve, nine flexor tendons, two synovial bursae, and peritendinous subsynovial connective tissue (SSCT). Fibrosis of the SSCT is the most consistent pathological finding in patients with carpal tunnel syndrome. We investigated the anatomy and gliding characteristics of the flexor digitorum superficialis tendon and its adjacent SSCT with high-resolution ultrasound (15 MHz). Our hypotheses were that tendon and SSCT are distinguishable by ultrasound and that their velocities during tendon excursion are different. Qualitative ultrasound analysis of a flexor tendon and its SSCT was performed on five cadaver wrists and correlated to respective findings after anatomical study of the same cadavers. Quantitative Doppler velocity analysis of eight cadaver wrists was done to assess the sliding movement of the tendon and its SSCT within the carpal tunnel. No significant difference was found between the thickness of SSCT measured by ultrasound and that measured directly after dissection. The SSCT moved slower than its flexor tendon. The SSCT velocities were statistically different from the tendon velocities (t-test, p>0.001). High-resolution ultrasound is a very precise method to display the anatomy of the tendon and SSCT within the carpal tunnel, and their different velocities can be detected with Doppler. Noninvasive assessment of the thickness and velocity of the tenosynovium in carpal tunnel syndrome by high-resolution sonography might be a new diagnostic tool for disorders affecting the SSCT, especially carpal tunnel syndrome.
Calculated valence photoemission for an Anderson model fluctuating between two magnetic configurations

We use the 1/N expansion to evaluate the leading-order valence photoemission for an (N=2j+1)fold-degenerate Anderson model where the two lowest atomic states are ${\mathit{f}}^{1}$ and ${\mathit{f}}^{2}$. We find for all valences a Kondo-like peak which although sharp, carries a large fraction of the available weight. An additional threshold contribution beginning at the first magnetic state evolves into a distinct charge fluctuation peak for valences nearer to 2. The large weight in the Kondo peak, together with the extended background, may account for the broad structures seen in photoemission spectroscopy measurements on uranium heavy-fermion systems.
The role of wintertime radiation in maintaining and destroying stable layers

Strong stable layers are a common occurrence during western Colorado's winter. Analysis of radiosonde observations indicate wintertime boundary layer heights are near 500 m. The terrain in this region consists of mountains that rise approximately 1500–2000 m above the ground to the east, providing an effective blocking barrier. An experiment is described to observe upwelling and downwelling, longwave and shortwave radiative fluxes at two sites in western Colorado during January and February 1992, for combinations of clear, cloudy, snow covered, and bare ground periods. Analysis of the observations and the surface energy budget for typical Bowen ratios provides a better understanding of the role of radiation in maintaining and destroying stable layers. During the day, the surface received a net gain of energy from radiation, while at night there was a net loss. Over snow, the 24-hour net radiative flux was small and either positive or negative. Over bare soil, the 24-hour net radiative flux was positive but still small. There is little difference in the net radiative flux between clear and cloudy days; the reduction of the incident solar flux by clouds is nearly compensated by the hindering of the longwave cooling. The cumulative effects of the 24-hour net radiative flux were negative over snow early in the experiment. The 24-hour values shifted to near zero as the snow albedo decreased and were positive for bare ground. If the daytime net radiative flux is partitioned into sensible and latent heat flux using typical Bowen ratios, the daytime sensible heat available for destroying boundary layers is small for the low solar angles of the winter season. With a Bowen ratio of 0.5, the daytime sensible heat flux available is only 0.3 to 1.2 MJ m−2 over a snow surface and 1.4 to 2.3 MJ m−2 over soil. These heat fluxes will not build a deep enough boundary layer to break a typical wintertime inversion. The 24-hour sensible heat flux was negative at both sites for the entire experiment with this Bowen ratio. The radiation observations and the use of typical Bowen ratios lead to the conclusion that the net radiation will sustain or strengthen a stable atmosphere in the winter season in western Colorado. Analysis of the radiosonde observations confirm this result as the boundary layer depths were less than 500 m early in the experiment and grew to only 700 m later in the experiment.
Perturbation mapping method for sensitivity analysis of three-dimensional cracks near a free surface

A perturbation mapping method and a computational procedure are presented for evaluating the sensitivity coefficients of the stress intensity factors for three-dimensional planar cracks near a free surface. The boundary integral equations for evaluating the sensitivity coefficient are solved by using the boundary element method. Each of the geometric parameters that affect the stress intensity factor (such as, crack orientation, distance from the free surface, and crack shape parameters) is given a perturbation which defines a mapping between the original and perturbed coordinate systems, from which the sensitivity coefficients are derived. The sensitivity coefficients obtained by the perturbation mapping method are validated by comparing them with those obtained by the finite difference method. Numerical results for penny-shaped and elliptical cracks are presented showing the variation of the sensitivity coefficients with various geometric and material parameters.
NEIGHBORHOOD RESEARCH FROM A SPATIALLY ORIENTED STRENGTHS PERSPECTIVE

Research investigating neighborhood effects on children and families has been largely deficit and individual-focused, investigated structural variables, and has typically produced equivocal findings and small effect sizes. We suggest an approach focused on community strengths and resources that stresses the role of measures of social interaction variables and the utilization of analytic strategies that model the spatial and nested nature of contextual effects. To that end, we offer a community resilience model that includes both community-level risk and protective factors, and suggests sources to obtain community-level strengths data. We also provide a guide for locating community resource data appropriate for use in neighborhood effects research utilizing geographical information systems, multilevel modeling, and spatial analytic strategies. Finally, we discuss the challenges and issues to be addressed in further developing a strategy for investigating neighborhood effects from a strengths perspective. © 2007 Wiley Periodicals, Inc. J Comm Psychol 35: 667–680, 2007.