cssi/SciSciGPT-SciSciNet huggingface dataset:
Faster teaching by POMDP planning

Both human and automated tutors must infer what a student knows and plan future actions to maximize learning. Though substantial research has been done on tracking and modeling student learning, there has been significantly less attention on planning teaching actions and how the assumed student model impacts the resulting plans. We frame the problem of optimally selecting teaching actions using a decision-theoretic approach and show how to formulate teaching as a partially-observable Markov decision process (POMDP) planning problem. We consider three models of student learning and present approximate methods for finding optimal teaching actions given the large state and action spaces that arise in teaching. An experimental evaluation of the resulting policies on a simple concept-learning task shows that framing teacher action planning as a POMDP can accelerate learning relative to baseline performance.
The Race to the Bottom in a Federal System: Lessons from the World of Trade Policy

A concern frequently expressed in policy discussions of both federalism and international trade is that the decentralized unitsstates in the first case, countries in the latterwill engage in interdependent behavior that will be detrimental to all. The fear expressed is that left to choose their own individual policies without external constraints, the separate entities will engage in "a race to the bottom." The rhetoric is common to federalism and international-tradepolicy discussions, and the same set of theoretical economic models and empirical studies is used to inform both conversations. The policy prescription also is similar in the two cases. In the international trade setting, countries, whether actual or potential trading partners, are characterized as participating in "a race to the bottom," and the remedy urged upon them is "harmonization." The vision evoked is of a group of misguided athletes who have run off in the wrong direction and who need, to make things right, only to transform themselves into a smooth-sounding a cappella singing group. Although the image of the remedy is less evocative in discussions of federalism, the call is again for some degree of uniformity brought about at the behest of the central government. The question is whether the common formulation accurately identifies an important problem, and if it does, whether the proposed solution is appropriate. In this Essay, I want to use the lens provided by discussions of the race to the bottom as an issue in international trade policy to refract light on concern about a race to the bottom in a federal system. I shall aigue that the putative problem of "a race to the bottom" may or may not be a serious and substantial concern, but that even if it is, "harmonization," as often described in discussions of international trade policy, is not the elixir it is held out to be. The case for
Accuracy of prenatal diagnosis of isolated aqueductal stenosis.

Objective The objective of this article is to determine the success rate of prenatally diagnosed isolated aqueductal stenosis (AS) as a first step in an evidence-based reassessment of ventriculoamniotic shunting for isolated AS. Methods Cases of ventriculomegaly at Magee-Womens Hospital between 2006 and 2013 were ascertained. AS was suspected when prenatal ultrasound and magnetic resonance imaging (MRI) demonstrated signs of pressure hydrocephalus. The prenatal diagnosis generated by ultrasound and MRI was compared with the postnatal diagnosis based upon neonatal neuroimaging. Results The initial query of the Magee-Womens Hospital database resulted in 370 cases of ventriculomegaly. After exclusion for associated central nervous system malformations, 110 cases of severe ventriculomegaly remained. The imaging studies on each fetus were reviewed, and cases of prenatally diagnosed AS were identified. The median gestational age of the ultrasound diagnosis and prenatal MRI was 23 weeks 3 days and 33 weeks 3 days, respectively. All cases of prenatally suspected isolated AS (six of six) and cases of AS with other associated central nervous system anomalies (six of six) were correctly identified. Conclusion An accurate prenatal diagnosis of isolated fetal AS is possible. This is an important first step in an evidence-based reassessment of ventriculoamniotic shunting for isolated AS. © 2014 John Wiley & Sons, Ltd.
QoS-Friendly Wavelength Assignment in Dynamic Wavelength-Routed Optical Networks

In-band crosstalk has been widely considered as a major transmission impairment that significantly impacts the bit error rate (BER) performance of lightpaths in circuit-switched all-optical wavelength-routed networks. Such crosstalk usually occurs when multiple wavelengths pass through an optical crossconnect node, and the magnitude of the crosstalk is largely dependent on the wavelengths assigned to the lightpaths. Traditional wavelength assignment (WA) schemes pay little regard to the physical layer quality of service (QoS), and hence cannot provide optimized network performance in practical networks with imperfect physical transmission media. In this paper, we first present our categorization of in-band crosstalk based on the location of crosstalk generation, then we propose two QoS-friendly WA approaches, one of which selects the wavelength based on the estimated BERs, and the other based on the weighted crosstalk number counting. The two approaches have different computation complexities. Numerical results show that both approaches can significantly improve the BER blocking rate by suppressing the created in-band crosstalk, but the BER-based approach generally gives the better performance at the price of more extensive computation.
Liver transplantation for wilson's disease: A single-center experience

Wilson's disease is a hereditary defect in copper excretion leading to the accumulation of copper in the tissues, with subsequent tissue damage. The most serious sequela is that of progressive central nervous system involvement. The use of orthotopic liver transplantation (OLT) has been controversial for those patients with neurological symptoms attributed to Wilson's disease. The aim of this study is to determine the effectiveness of OLT for patients with Wilson's disease, including those with neurological involvement attributed to copper accumulation in the central nervous system. OLT was performed in 45 patients (19 men [42.2%], 26 women [57.8%]) with Wilson's disease between 1971 and 1993 who were followed up for at least 4 years. The age at diagnosis of Wilson's disease ranged from 3 to 41 years (mean, 17.7 +/- 7.4 years). The age at OLT ranged from 8 to 52 years (mean, 22.3 +/- 9.4 years). Nineteen patients (42.2%) were aged younger than 18 years at OLT. The indications for OLT included chronic hepatic failure in 15 patients (33.3%) and fulminant (FHF) or subfulminant hepatic failure in 30 patients (66. 6%). All but 1 of the 19 pediatric patients (94.7%) were in the latter group. Twenty-five patients (55.5%) were receiving D-penicillamine, 9 patients for more than 1 year; none of the patients treated long term presented as FHF. Thirty-three patients (73.3%) survived more than 5 years after OLT. Fourteen patients (31%) died during the posttransplantation period; 7 of the 14 patients (50%) were aged younger than 18 years. Twelve patients died during the first 3 months after OLT of complications of disease and surgery, 10 of whom underwent transplantation for FHF. The other 2 patients died 6 and 9 years after transplantation of infectious problems. Eleven patients (24.4%) required retransplantation because of a primary nonfunctioning graft (n = 6), chronic rejection (n = 4), and hepatic artery thrombosis (n = 1). Seventeen patients (37.7%) presented with neurological abnormalities; 14 patients with Wilsonian neurological manifestations and 3 patients with components of increased intracranial pressure. Ten of the 13 surviving patients with hepatic insufficiency and neurological abnormalities at OLT showed significant neurological improvement. Our experience shows OLT is a life-saving procedure in patients with end-stage Wilson's disease and is associated with excellent long-term survival. The neurological manifestation of the disease can improve significantly after OLT. Earlier transplantation in patients with an unsatisfactory response to medical treatment may prevent irreversible neurological deterioration and less satisfactory improvement after OLT.
The effect of 5,6-dihydroxytryptamine on post-decapitation convulsions

Abstract Previous data (1) have shown that L-DOPA increases the duration of the clonic phase of post-decapitation convulsions (PDC) in mice. It was suggested that this effect is produced by depleting 5-hydroxytryptamine (5-HT) in the inhibitory bulbospinal pathways and thus enhancing reflex activity in the spinal cord. If this were true then L-DOPA administration should not influence clonic PDC in animals whose 5-HT pathways were destroyed. We therefore tested the effects of L-DOPA on mice 3 weeks after pretreatment with the 5-HT neurotoxin, 5,6-dihydroxytryptamine (5, 6-DHT) (50 μg/kg, intracerebroventricularly). All mice were given the peripheral decarboxylase inhibitor, Ro 4-4602. 5,6-DHT halved the brain 5-HT levels and significantly increased the duration of clonic PDC. The administration of L-DOPA (320 mg/kg i.p.) to 5,6 DHT treated mice did not produce any further significant increases in duration. The administration of 5-hydroxytryptophan (5-HTP) (100 mg/kg, i.v.) to 5,6-DHT treated mice, however, increased 5-HT to above control levels and reduced convulsions to control levels. Administration of both 5-HTP and L-DOPA to 5,6-DHT treated mice resulted in 5-HT levels and convulsion times which were also not significantly different from the controls. These data give additional indication that intact 5-HT nerve terminals are necessary for L-DOPA to prolong the duration of clonic PDC.
240s Loop Interactions Stabilize the T State of Escherichia coli Aspartate Transcarbamoylase

Abstract Here the functional and structural importance of interactions involving the 240s loop of the catalytic chain for the stabilization of the T state of aspartate transcarbamoylase were tested by replacement of Lys-244 with Asn and Ala. For the K244A and K244N mutant enzymes, the aspartate concentration required to achieve half-maximal specific activity was reduced to 8.4 and 4.0 mm, respectively, as compared with 12.4 mm for the wild-type enzyme. Both mutant enzymes exhibited dramatic reductions in homotropic cooperativity and the ability of the heterotropic effectors to modulate activity. Small angle x-ray scattering studies showed that the unligated structure of the mutant enzymes, and the structure of the mutant enzymes ligated with N-phosphonacetyl-l-aspartate, were similar to that observed for the unligated and N-phosphonacetyl-l-aspartateligated wild-type enzyme. A saturating concentration of carbamoyl phosphate alone has little influence on the small angle x-ray scattering of the wild-type enzyme. However, carbamoyl phosphate was able to shift the structure of the two mutant enzymes dramatically toward R, establishing that the mutations had destabilized the T state of the enzyme. The x-ray crystal structure of K244N enzyme showed that numerous local T state stabilizing interactions involving 240s loop residues were lost. Furthermore, the structure established that the mutation induced additional alterations at the subunit interfaces, the active site, the relative position of the domains of the catalytic chains, and the allosteric domain of the regulatory chains. Most of these changes reflect motions toward the R state structure. However, the K244N mutation alone only changes local conformations of the enzyme to an R-like structure, without triggering the quaternary structural transition. These results suggest that loss of cooperativity and reduction in heterotropic effects is due to the dramatic destabilization of the T state of the enzyme by this mutation in the 240s loop of the catalytic chain.
Generation of a membrane-bound, oligomerized pre-pore complex is necessary for pore formation by Clostridium septicum alpha toxin.

Department of Psychiatry, UCLA NeuropsychiatricInstitute and the West Los Angeles Department ofVeterans Affairs Medical Center, Los Angeles, California90025, USA.SummaryLow-temperature inhibition of the cytolytic activityof alpha toxin has facilitated the identiﬁcation of animportant step in the cytolytic mechanism of thistoxin. When alpha toxin-dependent haemolysis wasmeasured on erythrocytes at various temperatures itwas clear that at temperatures #158C the haemolysisratewas signiﬁcantly inhibited with little or no haemo-lysis occurring at 48C. Alpha toxin appeared to bindto and oligomerize on erythrocyte membranes withsimilar kinetics at 48C and 378C. The slight differ-ences in these two processes at 48C and 378C couldnot account for the loss of cytolytic activity at lowtemperature. At 48C alpha toxin neither stimulatedpotassium release from erythrocytes nor formed poresin planar membranes. In contrast, at temperatures$258C both processes proceeded rapidly. Pores thatwere opened in osmotically stabilized erythrocytescould not be closed by low temperature. Therefore,low temperature appeared to prevent the oligomer-ized complex from forming a pore in the membrane.These data support the hypothesis that alpha toxinoligomerizes into a membrane-bound, pre-pore com-plex prior to formation of a pore in a lipid bilayer.IntroductionAlpha toxin is the major lethal factor produced by Clos-tridium septicum, a major cause of non-traumatic gasgangrene in humans (Stevens et al., 1990). We havedetermined that alpha toxin is cytolytic and its mechanismis based on pore formation in the target membrane(Ballard et al., 1993). It is synthesized and secreted asan inactive protoxin (AT
Matching voice and face identity from static images

Previous research has suggested that people are unable to correctly choose which unfamiliar voice and static image of a face belong to the same person. Here, we present evidence that people can perform this task with greater than chance accuracy. In Experiment 1, participants saw photographs of two, same-gender models, while simultaneously listening to a voice recording of one of the models pictured in the photographs and chose which of the two faces they thought belonged to the same model as the recorded voice. We included three conditions: (a) the visual stimuli were frontal headshots (including the neck and shoulders) and the auditory stimuli were recordings of spoken sentences; (b) the visual stimuli only contained cropped faces and the auditory stimuli were full sentences; (c) we used the same pictures as Condition 1 but the auditory stimuli were recordings of a single word. In Experiment 2, participants performed the same task as in Condition 1 of Experiment 1 but with the stimuli presented in sequence. Participants also rated the model’s faces and voices along multiple “physical” dimensions (e.g., weight,) or “personality” dimensions (e.g., extroversion); the degree of agreement between the ratings for each model’s face and voice was compared to performance for that model in the matching task. In all three conditions, we found that participants chose, at better than chance levels, which faces and voices belonged to the same person. Performance in the matching task was not correlated with the degree of agreement on any of the rated dimensions.
The effects of school district spending priorities on the exit paths of beginning teachers leaving the district

Abstract This paper shows that teachers ending their first employment spells are more likely to transfer to another teaching position when state teacher salaries are increased or when they are leaving districts with high central office spending. Teachers are also more likely to leave teaching when they end spells in districts with high spending for classified instructional staff. The research is based on a new longitudinal dataset providing information on the career histories of 9,756 Washington teachers. The empirical work uses a generalized variant of a transition probability model and conducts simulations to explore the influence of omportant policy variables.
Identification of BCOX1, a novel gene overexpressed in breast cancer

Abstract The identification of tumor-associated antigens, which are specifically expressed in cancer tissues, is of utmost important for immunotherapy of breast cancer. We have combined in silico screening and experimental expression analysis to identify genes that are differentially expressed in breast carcinomas compared with their corresponding normal tissues. Using these approaches, we identified a novel gene, BCOX1, with overexpression in breast carcinoma. BCOX1 was highly homologous to KIAA0100, a hypothetical gene located on chromosome 17q11.2. RNA in situ hybridization shows that BCOX1 mRNA signal is mainly located in the cytoplasm of breast carcinoma epithelial cells, but not in those of normal epithelial cells, stroma cells and lymphocytes. Furthermore, mRNA expression of BCOX1 was moderately elevated in ductal in situ carcinoma (DCIS), peaked in invasive breast carcinoma (IBC) and metastatic breast carcinoma cells (MET) whereas absent in benign ductal epithelial cells. The predicted BCOX1 open reading frame of 666 bp encodes a putative protein of 222 amino acid residues with a calculated molecular weight of 24920 Da and a PI of 5.86. Computational analyses predict that the putative BCOX1 protein is a cytoplasmic protein. The functional relevance of this novel gene is yet to be determined. This study warrants further investigations to explore the molecular functions of BCOX1, and to determine its potential diagnostic and therapeutic applications for breast cancer.
Archaeology as Anthropology: A Case Study

Anthropological inferences, made possible by advances in techniques for collecting data in archeological field work and the processing of data with a computer, permit a comparison to be made between the modern western Pueblos and their prehistoric background. One point in the development of Pueblo social organization (approximately A.D. 1200) is examined and compared with the present.
Semiotic Technologies, Temporal Reckoning, and the Portability of Meaning - Or: Modern Modes of Temporality – Just How Abstract are They?

This essay is about meaning and measurement, with particular emphasis on the relation between semiotic technologies and temporal reckoning. It begins by theorizing four ways of framing time. Temporality as metricality focuses on the repetition of tokens of common types. Temporality as performativity focuses on the roots and fruits of a given event. Temporality as reckoning focuses on how one determines when an event occurred or how long an event lasted. And temporality as worldview focuses on the ways a given community (genre, public, discipline, philosophy, register, etc.) frames the nature of time. Temporality as reckoning is then used to question some entrenched claims about temporality as worldview. In particular, the claim that modern modes of temporality are ‘abstract’ (in comparison to so-called premodern, traditional, or everyday modes of temporality) is called into question. In place of pre-theoretical notions like abstraction (and similarly inadequate concepts, such as ‘commensuration,’ ‘quantification,’ and ‘objectification’) a set of fine-grained analytic distinctions is introduced. These may be used to theorize the conditions for and consequences of a technology being relatively portable: its meaningfulness being widely applicable and/or contextually independent. Reflexively, while this essay draws its examples and methods from the domain of time, its general claims are meant to be portable to other domains – from velocity and price to temperature and information.
Management of syncope following immunization.

Mary S. Hayney lowing immunization.1 From 1990 to 1995, a total of 697 reports of syncope were made (Table 2). Of particular note is the timing of the episodes. This timing may guide immunizers to ask their patients to remain seated and under observation for 15 minutes following immunization. Although nearly one fourth of the VAERS reports included a mention of rhythmic movements with loss of consciousness, none of the reports noted that a new seizure diagnosis was made. The authors speculated that since the tonic or clonic jerking movements were more likely to be reported for syncopal episodes within 15 minutes of immunization, these are more likely to be vasovagal responses rather than seizures. Most episodes of syncope are harmless, and the real issue is the fall associated with the loss of consciousness and postural tone. Six individuals in the Braun et al. study sustained serious head injuries during the syncopal episode.1 The affected individuals were older (aged 12 to 28 years) than the group overall, and they were therefore heavier than a young child—giving credence to the saying, “The bigger they are the harder they fall.” Also, of particular importance to immunizers is that five of the six fainters were adolescent boys and men. Because fainting is perceived as less acceptable for men in our society, they may be less likely to admit to presyncopal signs (see below). They may even Syncope occurs in a situation the patient perceives as distressing. Although no data are available, one could reasonably assume that known fainters are unlikely to seek immunization services in a pharmacy. The key issue though is that fainting can be unpredictable. Syncope with immunization has not been systematically studied, but it occurs, and individuals with a fear of needles sometimes selfdefer immunization.1,2
Conjugate Heat Transfer of an Internally Air-Cooled Nozzle Guide Vane and Shrouds

In order to assess the life of gas turbine critical components, it is essential to adequately specify their aerothermodynamic working environments. Steady-state analyses of the flow field and conjugate heat transfer of an internally air-cooled nozzle guide vane (NGV) and shrouds of a gas turbine engine at baseline operating conditions are numerically investigated. A high-fidelity CFD model is generated and the simulations are carried out with properly defined boundary conditions. The features of the complicated flow and temperature fields are revealed. In general, the Mach number is lower and the temperature is higher on the NGV pressure side than those on the suction side. There are two high temperature regions on the pressure side, and the temperature across the middle section is relatively low. These findings are closely related to the locations of the holes and outlets of the cooling flow passage, and consistent with the field observations of damaged NGVs. As a technology demonstration, the results pr...
Dielectronic Excitation and Recombination in Crystal Channels

In previous papers, in this volume, electron-ion recombination processes have been studied using either free-electron targets or targets of “almost-free” electrons which are loosely bound to atoms or molecules. In the former case, the techniques generally involve either merged electron-ion beams in “single-pass” configuration or in electron “coolers” in storage rings or observation of photons and associated charge state fractions in electron beam ion sources, in either the EBIS or EBIT configuration. These techniques are direct and, in the case of merged or crossed beam experiments, offer very high energy resolution.
Structure of a Fbw7-Skp1-cyclin E complex: multisite-phosphorylated substrate recognition by SCF ubiquitin ligases.

The ubiquitin-mediated proteolysis of cyclin E plays a central role in cell-cycle progression, and cyclin E accumulation is a common event in cancer. Cyclin E degradation is triggered by multisite phosphorylation, which induces binding to the SCFFbw7 ubiquitin ligase complex. Structures of the Skp1-Fbw7 complex bound to cyclin E peptides identify a doubly phosphorylated pThr380/pSer384 cyclin E motif as an optimal, high-affinity degron and a singly phosphorylated pThr62 motif as a low-affinity one. Biochemical data indicate that the closely related yeast SCFCdc4 complex recognizes the multisite phosphorylated Sic1 substrate similarly and identify three doubly phosphorylated Sic1 degrons, each capable of high-affinity interactions with two Cdc4 phosphate binding sites. A model that explains the role of multiple cyclin E/Sic1 degrons is provided by the findings that Fbw7 and Cdc4 dimerize, that Fbw7 dimerization enhances the turnover of a weakly associated cyclin E in vivo, and that Cdc4 dimerization increases the rate and processivity of Sic1 ubiquitination in vitro.
The effect of furosemide on sodium-22 uptake into cerebrospinal fluid and brain

The effect was studied of a saluretic agent on the uptake of sodium-22 into the CSF and cerebral cortex of nephrectomized rats. Furosemide, 1 mg/kg, was injected into the left lateral ventricle of the brain. Sodium-22 was injected intraperitioneally and the uptake of the isotope into CSF, cerebral cortex, skeletal muscle and plasma was measured at intervals from 0.25 hour to 24 hours. During the initial 4-hour period after injection of the sodium-22, the uptake of the isotope was reduced in the furosemide-treated animals. The maximum reduction in uptake occurred at the 0.25-hour time period. The CSF Na RSA of the treated animals was 37% less than that of the control animals. After about 8 hours there was no difference in sodium-22 uptake into the CSF between the control and treated animals.
Complement defense mechanisms

Abstract The susceptibility of complement-deficient individuals to various severe infections, and studies of the effector mechanisms involved in the destruction of infectious agents, demonstrate the importance of complement in providing an effective host defense system. It is also becoming increasingly apparent that complement not only plays a role in ‘natural’ defenses against infection and in enhancing the antibody-mediated effector mechanisms, but also influences adaptive immune responses directly.
Archimedes and the elements: Proposal for a revised chronological ordering of the Archimedean corpus

With the rediscovery by J. L. Heiberg of the manuscript of Archimedes' Method and its publication by him in 1907, a suspicion held for centuries by mathematicians and mathematical historians was at last corroborated by direct evidence: Archimedes had indeed applied in his discovery of geometric theorems a heuristic technique of analysis, although the highly formal synthetic proofs given in their demonstration concealed this fact. Disappointingly little effort has since been made to search for other indications of growth in the composition of Archimedes' treatises. In particular, no one has attempted to exploit the relative chronology determined by J. Torelli in 1792 for a major part of the corpus. Despite the potential of even this partial ordering for a deeper understanding of Archimedes' work, no subsequent edition, translation or commentary has retained it as the organizing principle. In the present reexamination of this question of Archimedean chronology, I will (1) show how tenuous are the foundations of the orderings now in standard usage; (2) present a chronological order which differs from the standard accepted sequence in certain important respects, notably, in the position of the Dimension of the Circle and the Method; and (3) distinguish an “early group” of studies from the “mature group”, employing as my criterion the predominantly Euclidean character of the techniques used in the former. I believe that the results of my inquiry have broader implications, as in reinterpreting as Archimedean certain contributions preserved by such later authors as Hero and Pappus.
Ontogenetic emergence of immunoglobulins in Rana pipiens larvae.

Abstract The emergence of immunoglobulins in developing Rana pipiens larvae was analyzed by a combination of radioisotope methods with physicochemical and immunological techniques previously used to establish the properties of immunoglobulins of adult frogs. It was found that tadpoles possessed γM immunoglobulins which resembled the γM macroglobulins of adult frogs. These proteins were first detectable in tadpoles at stage 25. γG molecules were not present at any stage of larval development. A protein intermediate in size between γM and γG constituted a major serum component in late metamorphic animals (stages 31 and 32). This protein was present in insufficient quantity to characterize it at this time. Larval frogs resembled lower vertebrates such as elasmobranchs and cyclostomes in possessing only the γM class of immunoglobulins. Furthermore, the ontogenetic order of appearance of immunoglobulins in R. pipiens paralleled that observed in birds and mammals. These findings emphasize the relevance of developing amphibian larvae as model systems for the delineation of detailed mechanisms of activation of genes specifying immunoglobulins.
Antibiotic use and risk of ischemic stroke in the elderly.

Abstract Purpose To determine whether treating infections with antibiotics that have antichlamydial activity decreases the risk of ischemic stroke in the elderly. Subjects and methods We analyzed data from 199 553 subjects 65 years and older in a health care claims database who had continuous health and pharmacy coverage for at least 2 years between January 1, 1991, and September 30, 1997. Using proportional hazards models with time-dependent covariates for prior antibiotic prescription and adjusting for cardiovascular risk factors, we determined the associations between antibiotic use and first claim for ischemic stroke (n = 7,335) during the observation period. Results Rates of stroke (per 1,000 person-years) were 6.64 for macrolides, 9.27 for quinolones, 7.49 for tetracyclines, 6.88 for penicillins, 7.97 for cephalosporins, 8.58 for trimethroprim-sulfamethoxazole, and 7.29 for subjects with no antibiotic claims. The adjusted hazard ratios (HR) were 0.94 (95% confidence interval [CI]: 0.87 to 1.01) for macrolides, 1.04 (95% CI: 0.91 to 1.18) for tetracyclines, 1.02 (95% CI: 0.95 to 1.08) for penicillins, and 1.00 (95% CI: 0.82 to 1.22) for trimethroprim-sulfamethoxazole. Subjects with claims for quinolone antibiotics (HR = 1.17; 95% CI: 1.09 to 1.26) and cephalosporins (HR = 1.09; 95% CI: 1.02 to 1.16) had a slightly higher risk of stroke. Conclusion Exposures to short courses of antibiotics are not associated with lower risk of ischemic stroke in patients aged 65 years and older.
The influence of river discharge on the thawing of sea ice, Mackenzie River Delta: albedo and temperature analyses

Multi-temporal satellite images, field observations and field measurements were used to investigate the mechanisms by which sea ice melts offshore from the Mackenzie River Delta. Satellite data recorded between April and August 1986 were corrected to a map projection and calibrated such that albedo and temperature values could be compared. Three stages in the melting of sea ice were identified: flooding (overflows), insolation and melting by warm river water. The albedo values of overflows were as much as 1/7 that of ice values while the albedo of ice decreased by 1/3 over the summer. Approximately two weeks after the overflows develop, sea surface temperatures rise as the river-discharge peaks and becomes the dominant source of energy. By this process, ice removal in the delta regime is initiated two months earlier than adjacent coasts with minimal runoff. However, the net result is only a two-week acceleration of ice removal in the delta region.
Role of rare earth cations in Y zeolite for hydrocarbon cracking.

Reaction kinetics data were collected for isobutane conversion over a series of ultra stable Y (USY) zeolite catalysts with and without rare earth cations and subjected to various extents of dealumination by steaming. We conducted these reaction studies at low temperatures (523−573 K) using isobutane feed streams containing known levels of isobutylene (100−400 ppm) so that the kinetics were controlled by bimolecular hydride transfer and oligomerization/β-scission processes with little or no participation of monomolecular initiation reactions. These experimental conditions led to stable catalyst performance with the main products of isobutane conversion being propane, n-butane, and isopentane, with smaller amounts of propylene, trans-2-butene, and cis-2-butene. The rates of formation of these products per Bronsted acid site (as counted by pyridine adsorption) depended exponentially on Bronsted acid site density, regardless of whether the catalyst contained rare earth cations. Kinetic modeling showed an exp...
Dual Pronouns in Semitics and an Evaluation of the Evidence for their Existence in Biblical Hebrew

In the context of establishing the pronominal dual forms of proto-Semitic, philologists sought for vestiges of such forms in different non-related branches of the Semitic family of languages. This paper starts with an updated reconstruction of the Proto-Semitic’s dual pronouns based on all the information at our hands, and consequently examines the evidence proposed in the literature for vestiges of these forms in the biblical consonantal text, especially the most recent support made by Rendsburg. In a list of publications Rendsburg proposed to strengthen this hypothesis by using statistical considerations. This paper will reject his conclusions and will refute his arguments by demonstrating that merely counting examples can be very misleading; either separately counting examples found in the same biblical context with some unique dialectical features falsely increases the number or, far worse, some examples should not even be considered at all since there are other motivations for the use of their peculiar forms.*
Recovery of forest structure and composition to harvesting in different strata of mixed even-aged central Appalachian hardwoods

Implementing nature-based silviculture requires understanding the structural and compositional changes that occur in forested stands under known disturbance types and intensities. The objectives were to assess the (a) resistance of hardwood forests to change, (b) their trajectory of recovery following disturbance, and (c) how closely resulting forests resemble original forests. We characterized tree structure and composition at three points in time (pre-disturbance, 1-year post-disturbance, and ∼15 years following disturbance) along a harvesting disturbance gradient created by removing trees in different forest canopy strata. Significant differences to pre-disturbance conditions were noted immediately post-harvest for tree basal area, density, species richness, and tree species composition; treatment differences were observed for all parameters except diversity. Plots exposed to the least extreme harvesting disturbances (cutting small and intermediate trees) had returned to pre-disturbance conditions for most parameters after 15 years, while the most extreme harvesting disturbance (cutting large trees) had not yet recovered. Although not initially resistant, Central Appalachian eastern hardwoods are fairly resilient to the removal of trees in the subcanopy or a mixture of the subcanopy and canopy; only the removal of solely canopy trees (i.e., high grading) and complete removal (i.e., clearcutting) appear to impose harvesting disturbances to which these forests may not be resilient.
Tamavidin 2-REV: An engineered tamavidin with reversible biotin-binding capability

A biotin-binding protein with reversible biotin-binding capability is of great technical value in the affinity purification of biotinylated biomolecules. Although several proteins, chemically or genetically modified from avidin or streptavidin, with reversible biotin-binding have been reported, they have been problematic in one way or another. Tamavidin 2 is a fungal protein similar to avidin and streptavidin in biotin-binding. Here, a mutein, tamavidin 2-REV, was engineered from tamavidin 2 by replacing the serine at position 36 (S36) with alanine. S36 is thought to form a hydrogen bond with biotin in tamavidin 2/biotin complexes and two hydrogen bonds with V38 within the protein. Tamavidin 2-REV bound to biotin-agarose and was eluted with excess free biotin at a neutral pH. In addition, the model substrate biotinylated bovine serum albumin was efficiently purified from a crude extract from Escherichia coli by means of single-step affinity chromatography with tamavidin 2-REV-immobilized resin. Tamavidin 2-REV thus demonstrated reversible biotin-binding capability. The Kd value of tamavidin 2-REV to biotin was 2.8-4.4×10(-7)M.Tamavidin 2-REV retained other convenient characteristics of tamavidin 2, such as high-level expression in E. coli, resistance to proteases, and a neutral isoelectric point, demonstrating that tamavidin 2-REV is a powerful tool for the purification of biotinylated biomolecules.
Self-Consistent Simulation of Hybrid Spintronic Devices

We present a generic model to simulate coupled electron-spin systems applicable to the whole range of non-interacting to interacting spins and apply our model to compare tri-layer and penta-layer spin-torque devices on the same platform showing significant reduction in the switching current for devices with anti-parallel contacts over those with parallel contacts.
Magnetic-field effects on the motion of a charged particle in a heat bath

In a recent paper, Ford, Lewis, and O'Connell [Phys. Rev. A 37, 4419 (1988)] considered a charged quantum particle moving in an arbitrary potential and linearly coupled to a heat bath, and they showed that the macroscopic equation describing the time development of the particle motion is in the form of a quantum generalized Langevin equation. We generalize these results to include the presence of an external magnetic field. We find that the magnetic field manifests itself in the presence of an additional term in the Langevin equation, which is the quantum generalization of the Lorentz force, but the magnetic field does not affect the memory function nor the random force appearing in the quantum Langevin equation. It follows that the noise-noise autocorrelation function, as well as the nonequal time commutator of the noise, is the same as that in the absence of a magnetic field. The case of a blackbody radiation heat bath is shown to be easily analyzed as a special case of our general formalism.
Actinide silicate binary glasses: Low temperature sol-gel preparation of uranium and thorium silicate glasses

Abstract Binary uranium silicate and thorium silicate glasses have been obtained by a sol-gel method starting with the oxides and TEOS (tetraethylorthosilicate). Expressed in the form x M a O b (1− x )SiO 2 , the glasses fall in the range; 0.0017 to 0.047, which corresponds to 0.17 to 4.68 mol% and, for uranium up to 19 wt% UO 3 , as determined by electron microprobe. These elements were incorporated as U(VI) (in the UO 2 +2 form) and Th(IV). The glasses were produced by densification at temperatures of 700 °C or less. Partial crystallization of uranium silicate occurs on heating at 800 °C or above. The infrared and visible spectra are reported.
Motorist Use of Safety Equipment: Expected Benefits or Risk Incompetence?

Seat belts, child safety seats, and motorcycle helmets are not used all the time by all drivers, parents, or riders when they travel. Since the safety advantages of these types of equipment are well established, nonuse could be due to risk incompetence. This article starts instead with risk competence to see to what extent use can be attributed to the net benefits expected by individual motorists. Logit analysis of microdata from the Nationwide Personal Transportation Study shows that use is more likely with larger perceived net benefits for all three types of motorists. They are therefore risk competent enough to respond to changes in net benefits in ways and degrees that are qualitatively and ordinally correct.
Glutaraldehyde nonbiologic monitors.

Glutaraldehyde was first synthesized by Harries and Tank in 1908, and first marketed as a chemosterilizer in 1963. Since that time, glutaraldehyde has been used extensively as a disinfectant and chemical sterilizing solution. Even though it is generally agreed that moist heat is the preferred method of sterilization for medical, dental and hospital instruments, glutaraldehyde is a relatively safe, simple-to-use and effective chemical solution that can sterilize heat-sensitive materials. Glutaraldehyde (1,5-pentanedial) has two free aldehyde groups that combine irreversibly with bacterial cell membranes and enzyme systems. These properties give glutaraldehyde its biocidal effect. Contact time with glutaraldehyde is critical if sterilization, rather than disinfection, is to be achieved. Sterilization time ranges from minutes to ten hours, depending upon bacterial type and conditions of the test results. Sterilization with glutaraldehyde solutions usually requires prolonged contact times. Manufacturer instructions must be strictly followed.
Interfacial shear strength of cast and directionally solidified NiAl-sapphire fiber composites

The feasibility of fabricating intermetallic NiAl-sapphire fiber composites by casting and zone directional solidification has been examined. The fiber-matrix interfacial shear strengths measured using a fiber push-out technique in both cast and directionally solidified composites are greater than the strengths reported for composites fabricated by powder cloth process using organic binders. Microscopic examination of fibers extracted from cast, directionally solidified (DS), and thermally cycled composites, and the high values of interfacial shear strengths suggest that the fiber-matrix interface does not degrade due to casting and directional solidification. Sapphire fibers do not pin grain boundaries during directional solidification, suggesting that this technique can be used to fabricate sapphire fiber reinforced NiAl composites with single crystal matrices.
An Investigation of a New Activated Clotting Time “MAX-ACT” in Patients Undergoing Extracorporeal Circulation

Activated clotting time (ACT) is a test used in the operating room for monitoring heparin effect. However, ACT does not correlate with heparin levels because of its lack of specificity for heparin and its variability during hypothermia and hemodilution on cardiopulmonary bypass (CPB). A modified ACT
On the Throughput of Hybrid-ARQ Under Statistical Queuing Constraints

Hybrid automatic repeat request (HARQ) is a high-performance communication protocol, leading to the effective use of the wireless channel and the resources with only limited feedback about the channel state information (CSI) to the transmitter. In this paper, the throughput of HARQ with incremental redundancy (IR) and fixed transmission rate is studied in the presence of statistical queuing constraints imposed as limitations on buffer overflow probabilities. In particular, tools from the theory of renewal processes and stochastic network calculus are employed to characterize the maximum arrival rates that can be supported by the wireless channel when HARQ-IR is adopted. Effective capacity is employed as the throughput metric, and a closed-form expression for the effective capacity of HARQ-IR is determined for small values of the quality-of-service (QoS) exponent. The impact of the fixed transmission rate, queuing constraints, and hard-deadline limitations on the throughput is investigated, and comparisons with type-I HARQ and HARQ with Chase Combining are provided.
Computational and Experimental Studies of Methyl Group Exchange between Palladium(II) Centers

The disproportionation of 2 equiv of (L)2Pd(CH3)(X) to form 1 equiv of (L)2Pd(CH3)2 and 1 equiv of (L)2Pd(X)2 could serve as a key step in the catalytic oxidative oligomerization of methane. The thermodynamics associated with this transformation have been evaluated as a function of the supporting ligands L and X using DFT calculations. With these calculations as a guide, we demonstrate the first experimental example of disproportionation of a PdII monomethyl complex to generate a PdII dimethyl species using (tBu-bpy)Pd(CH3)(CH2COCH3) (tBu-bpy = 4,4′-di-tert-butyl-2,2′-bipyridine) as the starting material.
All's not fair in pricing: An initial look at the dual entitlement principle

A new theory in economics (Kahneman, Knetsch, and Thaler, 1986a, b) contends that consumer judgments of seller fairness can explain why sellers in many industries do not raise prices to ration off excess demand. In a small study focusing on automated teller machines (ATM) fees, we obtain empirical support for KKT's prediction that unjustified price increases are perceived as unfair, while cost justification “legitimates” a price increase in consumers' eyes. We also find, however, that fairness perceptions are not significantly related to behavioral intentions (as the theory would suggest). Many respondents felt the fee was unfair but would not switch banks because of switching costs, while others felt the fee was fair but would switch banks because of the cumulative cost. Research directions are discussed.
Some highly fluorinated acyclic, cyclic, and polycyclic derivatives of Cl2NCF2CF2NCl2 and Cl2CNCCl2CCl2NCCl2

When Cl2NCF2CF2NCl2 is heated with CF2CFX (X = Cl, F) ClXCFCF2N(Cl)CF2CF2N(Cl)CF2CXClF (X = Cl, 2; F, 3) is formed. Mercury extracts chlorine fluoride from 2 and 3 to form new polyfluorobisazomethines, ClXCFCF2NCFCFNCF2CXClF (X = Cl, 4; F, 5). Photolysis of the product obtained from CCl2NCCl2CCl2NCCl2 with ClF, CF2ClN(Cl)CF ClCFClN(Cl)CF2Cl (6) gives another bisazomethine, CF2ClNCFCFNCF2Cl (7) with concomitant loss of Cl2. At 25°C, in the presence of CsF, 4 and 5 are cyclized to give (X = Cl, 8; F, 9), and 7 forms a bicyclic derivative at 100°C, (1). Addition of chlorine fluoride to 8 and to 1 produces (10) and (14), respectively. Photolysis of 10 results in the loss of CFCl3 to form (11), and 14 loses Cl2 and dimerizes to the hydrazine (15). The further addition of ClF to 11 gives rise to (12) which when photolyzed at 3000 A forms a second cyclic hydrazine, (13).
Geniculo‐striate connections in the rabbit. II. Cytoarchitectonic structure of the striate region and of the dorsal lateral geniculate body; organization of the geniculo‐striate projections

Retrograde changes in the dorsal lateral geniculate body were studied following cortical radiation lesios. The cytoarchitectonic structure of the striate region is described. The peristriate as well as the striate areas are shown to receive projections form the dorsal lateral geniculate body. Thus — as far as this set of connections is concerned — the peristriate are is a subdivision of the striate region. It is further shown that the striate region as defined cytoarchitectonically is —to the extent that it was validated — coextensive with the cortical projection area of the dorsal lateral geniculate body. The dorsal lateral geniculate body is divided into an alpha and a beta sector. Evidence indicates that each vertical column of cells in the striate region receives projections from an appropriate geniculate column which extends throughout the thickness of the alpha sector. The alpha cell columns project upon the striate region in an orderly manner. Details of this organization are described. The cells of the beta sector also project upon the striate region. Whether the pattern of this projection is similar to that of the alpha sector or is more generalized has not been established. Some electrophysiological and experimental-anatomical evidence relevant to the findings is discussed.
On input read-modes of alternating Turing machines

Abstract A number of input read-modes of Turing machines have appeared in the literature. To investigate the differences among these input read-modes, we study log-time alternating Turing machines of constant alternations. For each fixed integer k ⩾ 1 and for each read-mode, a precise circuit characterization is established for log-time alternating Turing machines of k alternations, which is a nontrivial refinement of Ruzzo's circuit characterization of alternating Turing machines. These circuit characterizations indicate clearly the differences among the input read-modes. Complete languages in strong sense for each level of the log-time hierarchy are presented, refining a result by Buss. An application of these results to computational optimization problems is described.