cssi/SciSciGPT-SciSciNet huggingface dataset:
Defect-diffusion models of relaxation

Abstract A model of molecular relaxation in glassy materials is presented to describe configurational fluctuations which decay via the mediation of mobile defects. A mild distribution of free-energy barriers impeding the defect motion can generate a wide distribution of waiting times between defect displacements. When the mean waiting time is longer than the time of an experiment, no characteristic time scale exists. This case directly yields the Kohlrausch- Williams-Watts (KWW) stretched exponential relaxation law. Correlations between defects described by the Ornstein-Zernicke theory of critical fluctuations cause aggregation of defects and produce a Vogel-Fulcher (VF) type law for the disappearance of singlet defects, and therefore a VF law for the dipole relaxation time. The model is also applied to predict the molecular weight dependence of mechanical relaxation times (physical aging) in glassy polymeric systems.
International Environmental Implications of Soviet Development of the Volga River

Hydrologic alteration of major rivers has the potential for environmental damage on an international scale. Soviet regulation of the Volga River is a case in point. Iran, bordering on the Caspian Sea to which the Volga is tributary, has been harmed by changes in the sea's physical and biological character which are partially attributable to Soviet modification of the Volga's natural flow regime. Soviet plans for southward diversion of flow from the European Arctic and Siberia, partially intended to alleviate the Caspian problem, could pose an even more serious international hazard. Possible adverse consequences range from further imperiling the survival of the Atlantic salmon to hemispheric, perhaps even global, climatic changes. The already apparent consequences of Volga development and possible future ramifications of related diversion measures emphasize the need for caution as well as international cooperation and consultation in planning the alteration of major river basins.
The computer in literary analysis: Using TACT with students

TACT, a freeware program from the University of Toronto's Centre for Computing in the Humanities, is a highly sophisticated tool for text retrieval; although written for experienced critics and researchers, it can teach undergraduate students to read literature in new, fresh ways. Without requiring that the user become either a programmer, linguist, mathematician, or statistician,TACT introduces the literature student to the computer as a research tool. Studies of imagery and symbolism, of structural patterns, and of prosody can result from the student's careful tagging of a literary text and can yield significant insights into the work of literature. Students who use the computer as such a tool learn to read literary texts more closely and to think more clearly about literary problems.
GENETIC FOOTPRINT OF THE TOXR-BINDING SITE IN THE PROMOTER FOR CHOLERA TOXIN

Summary The transmembrane DNA-binding protein, ToxR, of Vibrio cholerae is a global transcriptional regulator of virulence gene expression. ToxR has been shown to interact with promoter regions upstream of both the ctxAB operon encoding cholera toxin, and the regulatory gene toxT. Deletion analysis has shown that a repeated sequence, TTTTGAT, is required for ToxR binding and activation of the ctxAB promoter. However, this sequence is not found upstream of the toxT promoter. Genetic selections using P22 challenge phages were used to define sites within the promoter for ctxAB which are critical for ToxR-DNA interactions. Single-base-pair changes and deletion mutations that impair ToxR binding cluster within two regions: -57 to -69 within two of three tandem TTTTGAT sequences; and from -39 to -47, between the repeat sequences; and the -35 region of the promoter. ToxR does not bind to a synthetic target that has three tandem repeats which lack a flanking upstream and downstream sequence. These results suggest that the ToxR-binding site lies immediately upstream of the -35 position of the ctx promoter, and that the affinity of ToxR binding to this site is influenced by the repeat sequences.
Sensorineural Deafness and Seizures in Mice Lacking Vesicular Glutamate Transporter 3

The expression of unconventional vesicular glutamate transporter VGLUT3 by neurons known to release a different classical transmitter has suggested novel roles for signaling by glutamate, but this distribution has raised questions about whether the protein actually contributes to glutamate release. We now report that mice lacking VGLUT3 are profoundly deaf due to the absence of glutamate release from hair cells at the first synapse in the auditory pathway. The early degeneration of some cochlear ganglion neurons in knockout mice also indicates an important developmental role for the glutamate released by hair cells before the onset of hearing. In addition, the mice exhibit primary, generalized epilepsy that is accompanied by remarkably little change in ongoing motor behavior. The glutamate release conferred by expression of VGLUT3 thus has an essential role in both function and development of the auditory pathway, as well as in the control of cortical excitability.
Automatically Assessing Lexical Sophistication: Indices, Tools, Findings, and Application

This study explores the construct of lexical sophistication and its applications for measuring second language lexical and speaking proficiency. In doing so, the study introduces the Tool for the Automatic Analysis of LExical Sophistication (TAALES), which calculates text scores for 135 classic and newly developed lexical indices related to word frequency, range, bigram and trigram frequency, academic language, and psycholinguistic word information. TAALES is freely available; runs on Windows, Mac, and Linux operating systems; and has a simple graphic user interface that allows for batch processing of .txt files. The tool is fast, reliable, and outputs results to a comma-separated value file that can be accessed using spreadsheet software. The study examines the ability of TAALES indices to explain the variance in human judgments of lexical proficiency and speaking proficiency for second language (L2) learners. Overall, these indices were able to explain 47.5% of the variance in holistic scores of lexical proficiency and 48.7% of the variance in holistic scores of speaking proficiency. This study has important implications for second language acquisition, for assessing L2 learners' productive skills (writing and speaking), and for L2 pedagogy. Limitations and future directions are also discussed.
Team negotiation and perceptions of trustworthiness: The whole versus the sum of the parts.

In a team negotiation context, the authors empirically explored how judgments of team-level trust are derived from individual-level trust. Basing their argument on both the negativity bias and the discontinuity effect, the authors posit that people will focus most on the least trustworthy individual member of a team when making judgments about collective team-level trust. Findings from two studies demonstrate that perceptions of team trust are indeed lower than the average ratings of individual trust and are statistically equivalent to the least trusted member. In addition, compared with average individual trust levels, perceptions of collective team trust were found to be more predictive of (a) impasse rates in distributive negotiations and (b) the level of joint gain in integrative negotiations.
Statistical mechanical theory of electrolyte diffusion inside a charged membrane

Abstract The transport of an electrolyte solution across a charged medium (due to presence of localized ions) is rigorously considered. It is demonstrated that the ratio of diffusion coefficients of unlike ions should equal the ratio of their respective velocities under conditions of vanishing net electric current. The perturbation functions determining the partial frictional coefficients are evaluated in the spirit of Debye-Huckel formalism. The ratio of diffusion coefficients of two ions inside the charged medium are evaluated as functions of their local concentrations approximately. Analogies between assumed model and biological membrane transport are suggested.
The diffusion of carbon in solid cobalt

Abstract The non-linearity observed at high temperatures in the Arrhenius representation of data for the diffusivity of C in f.c.c. Co is related to the presence of C-atoms in tetrahedral sites in the interstitial solid solution. It is shown that only a small contribution to the observed phenomenon may be due to the ferromagnetic-paramagnetic transformation.
Immunohistochemical and Histologic Demonstration of Thyrotropic Cells of the Human Adenohypophysis

Immunostaining with an antiserum shown to react specifically with thyroid-stimulating hormone has delineated the thyrotropic cells of the human adenohypophysis. In presumably normal pituitaries these cells occupied principally the anteromedial area of the pars distalis and varied widely in abundance. Thyrotropic cells were virtually absent from the pituitaries of several patients with no known thyroid dysfunction but were abundant in the mucoid wedge area of a gland from a patient with diffuse thyroid hyperplasia and were very numerous throughout and formed a microadenoma in the gland of a patient with Schmidt's syndrome. Immunostaining intensity varied widely in a given pituitary. The cells with the most basophilia in histologic procedures were the most intensely immunoreactive, and those with slight acidophilia immunostained the least strongly. Most of the thyrotropic cells were chromophobic with the reference stains and displayed intermediate immunoreactivity. Synonyms from earlier histologic classific...
Influence of reticular mechanisms upon hypoglossal, trigeminal and phrenic activities.

Abstract Studies were undertaken to evaluate the hypothesis that mechanims within the reticular formation influence activities of nerves to muscles of the upper airways more than the bulbospina-phrenic system. In decerebrate, vagotomized, paralyzed and ventilated cats, activities of the phrenic, trigeminal, and the hypoglossal nerves were monitores. Activity of the pontile and medullary reticular formation was increased directly by electrical stimulation within the brainstem and indirectly by stimulating the sciatic nerve. Trigeminal and hypoglossal discharges increased more than phrenic during stimulating at many brainstem loci. Changes were typically maintained for one or more respiratory cycles following termination of stimulation. At some loci, activation of neurons by microinjections of glutamate increased trigeminal and hypoglossal activities more than phrenic. Although responses were extremely variable, activities of the trigeminal and/or hypoglossal nerves usually increased more than phrenic during stimulations of the sciatic nerve or upon termination of stimulation. The result support the conclusion that respiratory-modulated trigeminal and hypopglossal discharges are dependent upon reticular mechanimss for their expression.
Michaelis-Menten metabolite formation kinetics: equations relating area under the curve and metabolite recovery to the administered dose.

Abstract A computational approach which concomitantly determines the capacity-limited rate constants of parent drug elimination and metabolite formation is presented. The approach applies both the presently derived total excretory recovery versus dose relationships of the metabolite and the AUC versus dose relationships of the parent drug to identify the parameters. Three parent drug elimination conditions were assessed: pooled first-order, pooled Michaelis–Menten, and parallel first-order and pooled Michaelis–Menten kinetics. Model and parameter identification criteria are discussed. Literature data for theophylline and two of its metabolites in rats were examined to reveal pooled Michaelis–Menten elimination kinetics of theophylline and capacity-limited formation of the metabolites. The proposed technique is useful for quantitating commonly obtained nonlinear drug disposition data such as AUC and amount of metabolites excreted.
Cabinet Stability in Post-Communist Central Europe

The comparative record of cabinet stability shows interesting variation across the three most consolidated post-communist democracies: the Czech Republic, Hungary and Poland. Whereas each cabinet has been remarkably stable in post-communist Hungary, no cabinet has survived in its original composition in Poland. The cabinets that have been formed in the Czech Republic show a mixture of stability and instability: the conservative coalition government formed after the 1996 Czech elections collapsed after a little more than a year in office paving the way for early elections. In contrast, the single-party government formed by the Social Democratic Party (CSSD) after the 1998 polls has proved to be stable. In this article it is argued that cabinet stability both within and across the states can be consistently explained by the theory of dominant and central players.
Aircraft airglow intensity measurements: Variations in OH and OI (5577)

Spectrophotometric airglow intensity measurements of OH, O I 6300, hydrogen H alpha and oxygen Herzberg I bands by airborne laboratory
Fate of horseradish peroxidase in the secretion zone of the rat incisor enamel organ.

Abstract Adult CDF albino rats were killed from 10 min to 6 hr after a single intravenous dose of HRP. Experimental and control tissues were reacted for peroxidase activity and processed for light and electron microscopy. At 10 min, all extracellular spaces of the secretion zone showed reaction product. A reaction was also seen around Tomes' processes and in a layer of enamel spaces in the region of thin enamel. At later time intervals, reactions around Tomes' processes were also seen in regions of thicker enamel. Tracer was located preferentially at the growth fronts of rod and interrod enamel, and also diffused for some distance into enamel. From 2 to 6 hr, the enamel over the transition zone became heavily labeled. The tracer penetrated for more than 90 μm into the enamel and was localized mainly in the interrod enamel. Droplets of dense stippled material in the extracellular spaces between Tomes' processes did not mix with tracer, but sites which contain a light stippled material in the controls (extracellular spaces, vesicles within ameloblasts) showed a reaction. It is concluded that (1) the basal terminal bars of secretory ameloblasts do not impede the flow of large molecules, (2) the apical terminal bars are permeable in early secretion, become increasingly tight as secretion progresses, and are again permeable in the transition zone, (3) ameloblasts can shuttle large extracellular molecules towards the enamel growth fronts, (4) large molecules can diffuse into enamel; rod and interrod enamel differ with regard to the diffusion of large molecules, (5) ameloblasts phagocytose significant amounts of light stippled material. The possibility is considered that extracellular enamel precursor molecules move preferentially towards the enamel growth fronts, perhaps by a mechanism involving membrane flow, and diffuse through enamel in similar fashion as HRP.
Modulatory effects of testosterone on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced neurotoxicity.

: In this experiment, we examined the modulatory effects of testosterone on the parkinsonism-inducing drug 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) in two strains of mice. Orchidectomized male CD-1 and C57/BI mice were implanted with either empty Silastic capsules or capsules containing testosterone and subsequently treated with MPTP. A small area of the corpus striatum was removed for determination of dopamine (DA) content, whereas the remainder was superfused and used to measure L-DOPA (5 μM)-evoked DA release. In animals treated with MPTP, L-DOPA-evoked DA release was reduced significantly in CD-1 mice, but not in C57/BI mice, treated with testosterone. No differences in L-DOPA-stimulated DA release between MPTP- versus vehicle-treated mice was observed in either the CD-1 or C57/BI mice receiving empty Silastic capsules. Corpus striatum DA contents were more severely depleted in the MPTP-sensitive C57/BI versus the CD-1 mouse strain irrespective of hormone treatment. These results confirm previous results demonstrating differences in these two mouse strains in response to the neurotoxic effects of MPTP upon corpus striatum DA content. More interestingly, they show an important differential modulatory effect of testosterone upon L-DOPA-evoked DA release as a function of MPTP treatment and indicate that testosterone significantly alters the neurotoxic effects of MPTP in the CD-1 mouse.
On the baker's map and the simplicity of the higher dimensional Thompson groups $nV$

We show that the baker’s map is a finite product of transpositions (particularly pleasant involutions), and conclude from this that an existing very short proof of the simplicity of Thompson’s group V applies with equal brevity to the higher dimensional Thompson groups nV .
Technology and the family farm

It is one thing for innovation in agricultural practice to be implemented thoughtlessly; quite another for it to be opposed on principle. The introduction of bovine growth hormone is a case in point.
Nitrogen and hydrogen in bulk single-crystal ZnO

Abstract Zinc oxide (ZnO) is a wide band gap II–VI semiconductor with optical, electronic, and mechanical applications. Nitrogen is a promising acceptor dopant. Nitrogen–hydrogen (N–H) complexes were introduced into ZnO during chemical vapor transport (CVT) growth, using ammonia as a doping source. The N–H bond-stretching mode gives rise to an infrared (IR) absorption peak at 3151 cm−1 at liquid-helium temperatures. Along with passivating acceptors, hydrogen also acts as a shallow donor. In the previous work, we observed an IR peak at 3326 cm−1 that corresponds to a hydrogen donor. It is possible that this donor is actually a Ca-OH complex.
Analysis of series-parallel resonant converter

A frequency-domain steady-state analysis is given for a series-parallel resonant converter (SPRC) operating in the continuous conduction mode (CCM) using Fourier series techniques. Equations for performance parameters are derived under steady-state conditions to provide simple design tools. The topology of the SPRC combines the advantageous properties of both the series resonant converter (SRC) and the parallel resonant converter (PRC). The key results of the work are: a novel half-wave rectifier SPRC, conditions for obtaining high part-load efficiency; and several boundary frequencies and limiting conditions such as the capacitive/inductive load boundary and open-circuit and short-circuit cases. Experimental results measured for an 80-W converter above the resonance at different load resistances and input voltages show excellent agreement with the theoretical performance predicted by the equations. >
Strained-layer quantum well lasers grown by molecular beam epitaxy for longer wavelength high-speed applications

Strained layer GaInAs graded-index separate-confinement heterostructure quantum well lasers grown by molecular beam epitaxy (MBE) are now demonstrating performance comparable to, or superior to, those grown by organometallic vapor phase epitaxy. The improvement in performance of the MBE grown lasers is largely due to optimized growth conditions which result from previous studies of the growth of strained layer channels for strained modulation doped field effect transistors. In this presentation, discussion covers the range of growth conditions for strained layer GaInAs/GaAs structures, the properties of these strained layer materials, and the dc and microwave performance of lasers fabricated from layers grown under these conditions.
Retinal differences between light-tolerant and light-avoiding slugs (Mollusca: Pulmonata).

The fine structure of photoreceptors in the eye of a light-tolerant slug, Ariolimax californicus, was compared with that of a nocturnal slug, Limax maximus. There is a marked difference in the distribution of the 800 A microvesicles (photic vesicles) in the Type I sensory cells: massed distally beneath the microvilli, the light-sensitive organelles, in A. californicus; and aggregated basally near the nuclei in L. maximus. This finding supports our hypothesis that the vesicles are involved in photoreception. Additionally, L. maximus has a unique modification of endoplasmic reticulum in the receptoral process of the Type I sensory cell that is not seen in A. californicus. And the distribution and nature of the pigment granules in the supportive cells differ in the two species of slugs. Type II sensory cells and ganglion cells in A. californicus are described briefly.
Losses in Wheat Due to Waterlogging

Waterlogging stress is one of the limiting factors influencing wheat (Triticum aestivum L.) production, especially in the lower Mississippi valley. A rain-shelter experiment was designed to evaluate the trend response of nine wheat genotypes to four levels of waterlogging treatment: 0, 10, 20, and 30 d of flooding. Genotypes planted in polyvinil-chloride (PVC) containers 25 cm long by 10 cm in diameter were waterlogged in plastic tanks under controlled rain conditions. Results indicated significant linear responses for kernels per head and tillers per plant, significant linear and quadratic responses for yield and chlorophyll content, and significant linear and cubic responses for plant height. The linear trend was the most important component, explaining from 92 to 99% of the variability due to waterlogging. Linear prediction equations were obtained to describe the relationship between different traits and waterlogging stress. Losses in yield and yield components were evaluated in a field experiment with 15 genotypes under control and waterlogging treatment. Average yield losses of 44% were mainly caused by a decrease in tiller number and kernels per head. Under waterlogging treatment, tiller number and kernels per head were reduced by 41 and 20%, respectively. Screening of wheat genotypes revealed the potential for waterlogging tolerance in breeding material and identified tolerant cultivars useful for waterlogged environments. Terral LA 422', Shelby', and 'Pioneer 2691' were the most adapted genotypes for waterlogging treatments. Because of a significant interaction with waterlogging treatment, some of the high-yielding genotypes under non-flooded conditions such as 'Coker 9663' and FFR 502W' showed low tolerance to waterlogging. The results provided information on the methods quantifying losses from waterlogging and identified selection criteria for waterlogging tolerance in wheat.
On the reanalysis of the GISSI-Prevenzione.

The reanalysis1 of the results of the GISSI-Prevenzione secondary prevention trial appearing in this issue of Circulation greatly increases the importance of this large, well-conducted clinical trial. The original publication of the GISSI-Prevenzione2 reported that when 11 323 patients surviving a very recent myocardial infarction (MI) were randomized to 1.0 g daily of a concentrate of fish oil n-3 polyunsaturated fatty acids (PUFAs, n=2835), vitamin E (300 mg daily, n=2830), both (n=2830), or no treatment (n=2828) on top of usual pharmacological treatment and lifestyle, significant reductions in mortality were observed over the 42 months of follow-up. However, probably two or three features of the outcome drew the attention of the investigators. These were (1) the very early separation of the mortality curves (or probability of mortality) between the subjects receiving the n-3 supplement versus the control groups, (2) the absence of any reduction in plasma cholesterol levels, and (3) the finding that the major factor in the mortality reduction by n-3 PUFAs resulted from a striking 45% reduction in sudden cardiac deaths, which had not been a stated primary end point for the GISSI-Prevenzione trial. Indeed, an early reduction in mortality has become a hallmark of the beneficial effects of n-3 PUFAs on coronary heart disease. This relationship is further strengthened when the benefit occurs in the absence of a reduction in cholesterol levels. Both were noted by Burr and associates in their 1989 publication of the Death and Reinfarction Trial3 and in the Lyon Heart Study by DeLorgeril et al4 in 1994. So the GISSI Investigators wisely decided that a careful time-course analysis of the results of GISSI-Prevenzione was warranted, and their resulting present publication adds greatly to the importance of their investigations. See p 1897 The authors point out that the GISSI-Prevenzione was conducted …
Uniform Decay Rates and Attractors for Evolution PDE′s with Boundary Dissipation

Abstract The problem of obtaining uniform decay rates for linear and nonlinear boundary value problems with boundary dissipation has been largely studied in the last years in the context of boundary control theory where the existence of stabilizing boundary feedback is important. However, the problems were studied on a case by case basis, only for some particular types of boundary feedbacks and moreover, it was not clear to which extent nonlinear conservative terms and nonlinear boundary feed-backs can be allowed. Our goal here is to give a general approach for such problems, which is valid for all evolution P.D.E of hyperbolic or ultra-hyperbolic type. In addition, under stronger assumptions we consider the problem of existence of compact attractors. This work is essentially based on some a-priori estimates of Carleman′s type obtained by the author in a previous paper [27].
Drought Monitoring for Washington State: Indicators and Applications

Abstract A drought monitoring system (DMS) can help to detect and characterize drought conditions and reduce adverse drought impacts. The authors evaluate how a DMS for Washington State, based on a land surface model (LSM), would perform. The LSM represents current soil moisture (SM), snow water equivalent (SWE), and runoff over the state. The DMS incorporates the standardized precipitation index (SPI), standardized runoff index (SRI), and soil moisture percentile (SMP) taken from the LSM. Four historical drought events (1976–77, 1987–89, 2000–01, and 2004–05) are constructed using DMS indicators of SPI/SRI-3, SPI/SRI-6, SPI/SRI-12, SPI/SRI-24, SPI/SRI-36, and SMP, with monthly updates, in each of the state’s 62 Water Resource Inventory Areas (WRIAs). The authors also compare drought triggers based on DMS indicators with the evolution of drought conditions and management decisions during the four droughts. The results show that the DMS would have detected the onset and recovery of drought conditions, in m...
Combination of retinoic acid and ursodeoxycholic acid attenuates liver injury in bile duct-ligated rats and human hepatic cells.

Cholestasis leads to liver cell death, fibrosis, cirrhosis, and eventually liver failure. Despite limited benefits, ursodeoxycholic acid (UDCA) is the only Food and Drug Administration–approved treatment for cholestatic disorders. Retinoic acid (RA) is a ligand for nuclear receptors that modulate bile salt homeostasis. RA also possesses immunomodulatory effects and is used to treat acute promyelocytic leukemia and inflammatory disorders such as psoriasis, acne, and rheumatoid arthritis. To test whether the supplementation of RA with UDCA is superior to UDCA alone for treating cholestasis, male Sprague-Dawley rats underwent common bile duct ligation (BDL) for 14 days and were treated with phosphate-buffered saline (PBS), UDCA, all-trans retinoic acid (atRA), or UDCA and atRA by gavage. Treatment with UDCA and atRA substantially improved animal growth rates, significantly reduced liver fibrosis and bile duct proliferation, and nearly eliminated liver necrosis after BDL. Reductions in the bile salt pool size and liver hydroxyproline content were also seen with treatment with atRA or atRA and UDCA versus PBS and UDCA. Furthermore, atRA and UDCA significantly reduced liver messenger RNA and/or protein expression of transforming growth factor β1 (Tgf-β1), collagen 1a1 (Col1A1), matrix metalloproteinase 2 (Mmp2), cytokeratin 19, α-smooth muscle actin (α-SMA), cytochrome P450 7A1 (Cyp7a1), tumor necrosis factor α, and interleukin-β1. The molecular mechanisms of this treatment were also assessed in human hepatocytes, hepatic stellate cells, and LX-2 cells. atRA alone or in combination with UDCA greatly repressed CYP7A1 expression in human hepatocytes and significantly inhibited COL1A1, MMP2, and α-SMA expression and/or activity in primary human hepatic stellate cells and LX-2 cells. Furthermore, atRA reduced TGF-β1–induced Smad2 phosphorylation in LX-2 cells. Conclusion: Our findings indicate that the addition of RA to UDCA reduces the bile salt pool size and liver fibrosis and might be an effective supplemental therapy with UDCA for cholestatic diseases. (HEPATOLOGY 2011;53:548-557.)
Spontaneous atomic line shapes from an argon ion laser discharge

Abstract Spontaneously emitted atomic line shapes from an argon ion laser discharge have been measured with a plane parallel Fabry-Perot interferometer. The interferometer and its associated data reduction programs were carefully characterized so that Lorentzian widths on the order of 0.004 of the interferometer free spectral range could be measured. The observed line shapes were analyzed in terms of thermal Doppler broadening, Stark broadening by electrons and natural broadening. Electron densities calculated from the Stark broadening were discrepant by factors of 5–10. An alternative line-shape model, which includes a non-thermal velocity distribution function, is proposed.
Upper limits to the interstellar radiation field between 775 and 1050 Å.

A 40-A resolution extreme-ultraviolet spectrometer, sensitive to radiation in the 775-1050 A band, was flown on a Black Brant VC rocket to measure the night sky brightness in this region of the electromagnetic spectrum. A weak signal above background was recorded in most channels as the spectrometer's field of view scanned the sky in the vicinity of the galactic plane from Monoceros to Andromeda. Because the earth's upper atmosphere may produce some radiation in this wavelength region, the possibility cannot be excluded that some or all of the observed signal is terrestrial in origin. However, observational upper limits can be established at the 95-per cent confidence level for the intensity of an extraterrestrial extreme ultraviolet background which ranges from 6 millionths erg/sq cm/s/sr/A at 1050 A to 4 ten-millionths erg/sq cm/s/sr/A at 775 A. These results are consistent with existing theoretical predictions.
Phytophagous insect faunas of two introduced Cirsium thistles, C. ochrocentrum and C. vulgare, in southern California.

Phytophagous insects in seven orders, 18 families, 27 genera, and 30 species are reported as composing the insect fauna of bull thistle, Cirsium vulgare (Savi) Tenore, a weed introduced from Europe into southern California. Similarly, phytophagous insects representing four orders, six families, six genera, and seven species are reported from a single population of yellow-spine thistle, C. ochrocentrum A. Gray, also an introduced thistle, but native to states east of California. Most insects attacking bull thistle are polyphagous, ectophagous, sap- and foliage-feeding species. Seventeen (61%) of the 28 identified insect species reported from bull thistle also occur on native Cirsium thistles in southern California. Six (35%) of the 17 insect species feeding on bull thistle as well as native species of Cirsium are stenophagous (i.e., apparently restricted to host plants in the subtribe Carduinae). All six identified species reported from yellow-spine thistle also occur on native Cirsium thistles in southern California, including three endophages and two oligophages (i.e., apparently restricted to the genus Cirsium ). Faunal characteristics suggest that yellow-spine thistle is related more closely to Cirsium thistles native to southern California than to bull thistle.
Least-Cost Ration Formulations for Holstein Dairy Heifers By Using Linear and Stochastic Programming

Four mathematical programming models were developed to formulate rations for large breed replacement dairy heifers in each of 11 different weight classes from 50 to 550 kg and daily growth rates of 600, 700, and 800 g, with the objective of achieving a final calving weight of 600 kg. First, a base linear programming model was developed; then, to account for variability in the crude protein content of ration ingredients three other methods were used: right-hand side adjustment, incorporation of a safety margin, and stochastic programming. The average daily cost to calving, given a daily gain of 600, 700, and 800 g, was $0.62, $0.64, and $0.68, respectively. The total feed cost to 600 kg was $89.87 more for a growth rate of 600 over 800 g/d. The stochastic programming model performed better, on the bases of cost and protein-feeding, than did the right-hand side adjustment or the safety margin methods. The stochastic programming model over-adjusted crude protein by 5% and cost an average of 3.5% more than the linear programming solution for a dairy heifer growing at 800 g/d with a desired probability of 80% of crude protein intake achieving the NRC minimum. The other two methods over-adjusted crude protein by 10 and 13% and cost an extra 5.5 and 7.6%, respectively, for the right-hand side adjustment and the safety margin methods.
BACKPROPAGATION LEARNING FOR MULTILAYER FEED-FORWARD NEURAL NETWORKS USING THE CONJUGATE GRADIENT METHOD

In many applications, the number of interconnects or weights in a neural network is so large that the learning time for the conventional backpropagation algorithm can become excessively long. Numerical optimization theory offers a rich and robust set of techniques which can be applied to neural networks to improve learning rates. In particular, the conjugate gradient method is easily adapted to the backpropagation learning problem. This paper describes the conjugate gradient method, its application to the backpropagation learning problem and presents results of numerical tests which compare conventional backpropagation, steepest descent and the conjugate gradient methods. For the parity problem, we find that the conjugate gradient method is an order of magnitude faster than conventional backpropagation with momentum.
Identification of Conserved and Species-Specific Functions of the Listeria monocytogenes PrsA2 Secretion Chaperone

The Gram-positive bacterium Listeria monocytogenes is a facultative intracellular pathogen that relies on the regulated secretion and activity of a variety of proteins that sustain life within diverse environments. PrsA2 has recently been identified as a secreted peptidyl-prolyl cis/trans isomerase and chaperone that is dispensable for bacterial growth in broth culture but essential for L. monocytogenes virulence. Following host infection, PrsA2 contributes to the proper folding and activity of secreted proteins that are required for bacterial replication within the host cytosol and for bacterial spread to adjacent cells. PrsA2 is one member of a family of Gram-positive secretion chaperones that appear to play important roles in bacterial physiology; however, it is not known how these proteins recognize their substrate proteins or the degree to which their function is conserved across diverse Gram-positive species. We therefore examined PrsA proteins encoded by a variety of Gram-positive bacteria for functional complementation of L. monocytogenes mutants lacking prsA2. PrsA homologues encoded by Bacillus subtilis, Streptococcus pyogenes, Streptococcus pneumoniae, Streptococcus mutans, Staphylococcus aureus, and Lactococcus lactis were examined for functional complementation of a variety of L. monocytogenes PrsA2-associated phenotypes central to L. monocytogenes pathogenesis and bacterial cell physiology. Our results indicate that while selected aspects of PrsA2 function are broadly conserved among diverse Gram-positive bacteria, PrsA2 exhibits unique specificity for L. monocytogenes target proteins required for pathogenesis. The L. monocytogenes PrsA2 chaperone thus appears evolutionarily optimized for virulence factor secretion within the host cell cytosol while still maintaining aspects of activity relevant to more general features of Gram-positive protein translocation.
Emergent Literacy: Children’s Books from 0 to 3 edited by Bettina Kümmerling-Meibauer

This collection of essays concerns itself with “emergent literacy” in two senses. Its authors explicitly investigate the experiences of very young children as they gain awareness of and access to p...
Restoration of cerebrovascular CO2 responsivity by glutamine synthesis inhibition in hyperammonemic rats.

Hyperammonemia increases brain glutamine levels, causes astrocytic swelling, and depresses cerebral blood flow (CBF) responsivity to CO2. Methionine sulfoximine (MSO) inhibition of glutamine synthetase activity, known to be enriched in astrocytes, prevents ammonia-induced increases in brain glutamine and water content. We tested the hypothesis that inhibition of glutamine accumulation restores CBF responsivity to CO2 during acute hyperammonemia. Pentobarbital-anesthetized rats treated with either vehicle or MSO (150 mg/kg i.p.) received a 6-hour intravenous infusion of either sodium or ammonium acetate. With subsequent induction of hypercapnia, CBF increased from 113 +/- 14 (mean +/- SEM) to 194 +/- 9 ml/min per 100 g in control rats but was unchanged from 107 +/- 13 to 79 +/- 10 ml/min per 100 g in hyperammonemic rats. Treatment with MSO in hyperammonemic rats restored the CBF response to hypercapnia (from 73 +/- 8 to 141 +/- 14 ml/min per 100 g). With induction of hypocapnia, CBF decreased from 114 +/- 11 to 88 +/- 11 ml/min per 100 g in control rats but increased from 112 +/- 13 to 142 +/- 19 ml/min per 100 g in hyperammonemic rats. Treatment with MSO in hyperammonemic rats did not fully restore the response to hypocapnia but prevented the paradoxical increase in CBF (from 80 +/- 8 to 80 +/- 8 ml/min per 100 g). In control rats, MSO did not affect CO2 responsivity. Treatment with MSO prevented ammonia-induced increases in intracranial pressure. Hyposmotic-induced increases in brain water content and intracranial pressure attenuated the CBF response to hypercapnia but, unlike hyperammonemia, did not attenuate the response to hypocapnia. In contrast to hypercapnia, vasodilation in response to arterial hypotension was intact in hyperammonemic rats. We conclude that the grossly abnormal CBF responsivity to CO2 alterations during hyperammonemia is linked to glutamine accumulation rather than ammonia per se. Cerebral edema secondary to glutamine accumulation may contribute in part to abnormal CBF responses, although other aspects of astrocyte dysfunction are likely to be important.
Timing Verification with Crosstalk for Transparently Latched Circuits

Delay variation due to crosstalk has made timing analysis a hard problem. In sequential circuits with transparent latches, crosstalk makes the timing verification (also known as clock schedule verification) even harder. In this paper, we point out a false negative problem in current timing verification techniques and propose a new approach based on switching windows. In this approach, coupling delay calculations are combined naturally with latch timing iterations. A novel algorithm is given for timing verification with crosstalk in transparently latched circuits and primitive experiments show promising results.
Accounting for cross-national differences in infant mortality decline (1965-1991) among less developed countries : Effects of women's status, economic dependency, and state strength

The present study tests models derived from four theoretical perspectives: Modernization/free trade theory, gender inequality theory, developmental state theory, and dependency theory. It is based on a sample of 82 less developed countries for the period from 1965 to 1991. We find some support for each theoretical perspective. Foreign trade, investment, and debt dependency have adverse effects on infant mortality, mediated by variables linked to modernization/free trade theory and gender inequality theory. State strength has a beneficial direct effect on infant mortality decline. Women's education and reproductive autonomy have significant direct effects, but also play important roles as mediating variables as does rate of economic growth.
Electro-Thermal Analysis of Oxide-Confined Vertical-Cavity Lasers

The performance of oxide-confined vertical-cavity lasers (VCLs) can be severely limited by current leakage and self-heating. This paper investigates electrical and thermal effects of lateral oxidation on wafer-bonded 1.55 μm VCLs. Measurements are combined with two-dimensional finite-element simulations to analyze internal device physics. Charged defects at the p-side fused interface are found to increase the threshold voltage as well as lateral current spreading. An optimum oxide aperture for minimum device heating is calculated. Loss reductions are predicted to lead to a minimization of self-heating with small apertures.
The Influence of Primary Children's Ideas in Science on Teaching Practice

The purpose of this study was to explore how children's ideas in science affects science in- struction in the primary grades. The study investigated whether and how primary teachers recognize stu- dent ideas, and whether and how they react to student ideas. Two experienced second-grade teachers and one intern teacher were observed and videotaped as they taught 8-week astronomy units. Teachers and stu- dents from each classroom were pre- and postinstruction interviewed for their content knowledge of and viewpoints on teaching and the importance of student ideas. Midunit stimulated recall interviews were used to gain understanding of teachers' perceptions of their instruction regarding student ideas. Transcripts of lessons and interviews were coded and analyzed for patterns of eliciting and addressing student ideas. Re- sults showed that all teachers used discussions in a variety of ways to identify and elicit student ideas. The experienced teacher with the highest level of content knowledge had the largest repertoire for eliciting and addressing student ideas. The intern teacher addressed student ideas in ways that discouraged students from continuing to share their ideas. Implications include (a) helping teachers to use their teaching strengths to increase their content knowledge and expertise teaching primary students, (b) helping preservice teachers to develop a deeper understanding of characteristics of the learner, (c) having science educators recognize that primary teachers' goals for instruction focus on developing literate readers and writers and the im- portance of fitting science into those goals, and (d) recognizing that experienced teachers with knowledge of the importance of student ideas may seek to improve their own content knowledge. © 2000 John Wiley & Sons, Inc. J Res Sci Teach 37: 363-385, 2000.
A low level of reactive oxygen species selects for primitive hematopoietic stem cells that may reside in the low-oxygenic niche

A low-oxygenic niche in bone marrow limits reactive oxygen species (ROS) production, thus providing long-term protection for hematopoietic stem cells (HSCs) from ROS stress. Although many approaches have been used to enrich HSCs, none has been designed to isolate primitive HSCs located within the low-oxygenic niche due to difficulties of direct physical access. Here we show that an early HSC population that might reside in the niche can be functionally isolated by taking advantage of the relative intracellular ROS activity. Many attributes of primitive HSCs in the low-oxygenic osteoblastic niche, such as quiescence, and calcium receptor, N-cadherin, Notch1, and p21 are higher in the ROSlow population. Intriguingly, the ROSlow population has a higher self-renewal potential. In contrast, significant HSC exhaustion in the ROShigh population was observed following serial transplantation, and expression of activated p38 mitogen-activated protein kinase (MAPK) and mammalian target of rapamycin (mTOR) was higher in this population. Importantly, treatment with an antioxidant, a p38 inhibitor, or rapamycin was able to restore HSC function in the ROShigh population. Thus, more potent HSCs associated with the low-oxygenic niche can be isolated by selecting for the low level of ROS expression. The ROS-related signaling pathways together with specific characteristics of niche HSCs may serve as targets for beneficial therapies.
Capillary versus venous haemoglobin determination in the assessment of healthy blood donors.

Background and Objectives To determine the accuracy of fingerstick haemoglobin assessment in blood donors, the performance of a portable haemoglobinometer (HemoCue Hb 201+) was prospectively compared with that of an automated haematology analyzer (Cell-Dyn 4000). Haemoglobin values obtained by the latter were used as the ‘true’ result. Material and Methods Capillary fingerstick samples were assayed by HemoCue in 150 donors. Fingerstick samples from two sites, one on each hand, were obtained from a subset of 50 subjects. Concurrent venous samples were tested using both HemoCue and Cell-Dyn devices. Results Capillary haemoglobin values (HemoCue) were significantly greater than venous haemoglobin values (HemoCue), which in turn were significantly greater than venous haemoglobin values by Cell-Dyn (mean ± SD: 14·05 ± 1·51, 13·89 ± 1·31, 13·62 ± 1·23, respectively; P < 0·01 for all comparisons among groups). Nine donors (6%) passed haemoglobin screening criteria (≥12·5 g/dl) by capillary HemoCue, but were deferred by Cell-Dyn values (false-pass). Five donors (3%) were deferred by capillary sampling, but passed by Cell-Dyn (false-fail). Substantial variability in repeated fingerstick HemoCue results was seen (mean haemoglobin 13·72 vs. 13·70 g/dl, absolute mean difference between paired samples 0·76 g/dl). Hand dominance was not a factor. Conclusions Capillary samples assessed via a portable device yielded higher haemoglobin values than venous samples assessed on an automated analyzer. False-pass and false-fail rates were low and acceptable in the donor screening setting, with ‘true’ values not differing by a clinically significant degree from threshold values used to assess acceptability for blood donation.
Material response during nanosecond laser induced breakdown inside of the exit surface of fused silica

The material response following nanosecond, UV laser induced breakdown inside of the exit surface of fused silica is investigated using multimodal time resolved microscopy. The study spans up to about 75 ns delay from the onset of material modification during the laser pulse through the observation of material ejection. A number of distinct processes were identified, including: a) the onset of optical absorption in the material arising from the buildup of an electronic excitation, b) the expansion of the hot modified region (plasma) along the surface and inside the bulk, c) the formation of radial and circumferential cracks, d) the swelling of the affected region on the surface and, e) the onset of ejection of material clusters at about 30 ns delay and its progression to a well-defined jet by about 75 ns delay. Limited theoretical modeling is used to aid the interpretation of the data.