cssi/SciSciGPT-SciSciNet huggingface dataset:
Implied and local volatilities under stochastic volatility

For asset prices that follow stochastic-volatility diffusions, we use asymptotic methods to investigate the behavior of the local volatilities and Black–Scholes volatilities implied by option prices, and to relate this behavior to the parameters of the stochastic volatility process. We also give applications, including risk-premium-based explanations of the biases in some naive pricing and hedging schemes. We begin by reviewing option pricing under stochastic volatility and representing option prices and local volatilities in terms of expectations. In the case that fluctuations in price and volatility have zero correlation, the expectations formula shows that local volatility (like implied volatility) as a function of log-moneyness has the shape of a symmetric smile. In the case of non-zero correlation, we extend Sircar and Papanicolaou's asymptotic expansion of implied volatilities under slowly-varying stochastic volatility. An asymptotic expansion of local volatilities then verifies the rule of thumb that local volatility has the shape of a skew with roughly twice the slope of the implied volatility skew. Also we compare the slow-variation asymptotics against what we call small-variation asymptotics, and against Fouque, Papanicolaou, and Sircar's rapid-variation asymptotics. We apply the slow-variation asymptotics to approximate the biases of two naive pricing strategies. These approximations shed some light on the signs and the relative magnitudes of the biases empirically observed in out-of-sample pricing tests of implied-volatility and local-volatility schemes. Similarly, we examine the biases of three different strategies for hedging under stochastic volatility, and we propose ways to implement these strategies without having to specify or estimate any particular stochastic volatility model. Our approximations suggest that a number of the empirical pricing and hedging biases may be explained by a positive premium for the portion of volatility risk that is uncorrelated with asset risk.
Possibilistic Clustering Based on Robust Modeling of Finite Generalized Dirichlet Mixture

We propose a novel possibilistic clustering algorithm based on robust modelling of the Generalized Dirichlet (GD) finite mixture. The algorithm generates two types of membership degrees. The first one is a posterior probability that indicates the degree to which the point fits the estimated distribution. The second membership represents the degree of “typicality” and is used to indentify and discard noise points. The algorithm minimizes one objective function to optimize GD mixture parameters and possibilistic membership values. This optimization is done iteratively by dynamically updating the Dirichlet mixture parameters and the membership values in each iteration. We compare the performance of the proposed algorithm with an EM based approach. We show that the possibilistic approach is more robust.
Aortic valve replacement in children: Options and outcomes

Several disease pathologies such as congenital heart disease and rheumatic fever can affect the aortic valve (AV) in children frequently necessitating intervention. While percutaneous or surgical AV repair is recommended as initial management strategy in children with AV disease, AV replacement (AVR) might become necessary in children with significant valve destruction and after repair or intervention failure. AVR in children is associated with distinct clinical and technical problems owing to several anatomic, social and prosthesis-related issues. In the current review, we list different AV substitutes, discuss their advantages and shortcomings, outline AVR results in children, and explore the divergence of outcomes in various age, anatomy and pathology subgroups; all in the aim to identify optimal AVR choice for each patient taking into consideration his unique anatomic and demographic characteristics.
Peripheral hot spots for local Ca2+ release after single action potentials in sympathetic ganglion neurons.

Ca2+ release from the endoplasmic reticulum (ER) contributes to Ca2+ transients in frog sympathetic ganglion neurons. Here we use video-rate confocal fluo-4 fluorescence imaging to show that single action potentials reproducibly trigger rapidly rising Ca2+ transients at 1–3 local hot spots within the peripheral ER-rich layer in intact neurons in fresh ganglia and in the majority (74%) of cultured neurons. Hot spots were located near the nucleus or the axon hillock region. Other regions exhibited either slower and smaller signals or no response. Ca2+ signals spread into the cell at constant velocity across the ER in nonnuclear regions, indicating active propagation, but spread with a (time)1/2 dependence within the nucleus, consistent with diffusion. 26% of cultured cells exhibited uniform Ca2+ signals around the periphery, but hot spots were produced by loading the cytosol with EGTA or by bathing such cells in low-Ca2+ Ringer's solution. Peripheral hot spots for Ca2+ release within the perinuclear and axon hillock regions provide a mechanism for preferential initiation of nuclear and axonal Ca2+ signals by single action potentials in sympathetic ganglion neurons.
Residual altered α-mannosidase in human mannosidosis

Abstract The apparent Km of residual acidic α-mannosidase detected in fibroblast extracts from four unrelated patients with mannosidosis was increased to >25mM for a fluorogenic substrate compared to 0.86–0.96mM for controls. The mutant enzyme was also more labile with heat treatment. These findings indicate a mutation in the structural gene for this enzyme. The altered kinetics of mutant enzyme can result in apparently normal enzyme specific activity at high concentrations of fluorogenic substrate creating potential for errors in the diagnosis of mannosidosis.
Expedited partner therapy for scabies: Legal and ethical considerations

Dr Itch is evaluating a young man named Sam who has pruritic papules on his hands and genitals. A mineral oil preparation confirms scabies. Dr Itch recommends treatment with permethrin cream. Sam reveals that he lives with his girlfriend and brother, both of whom have developed symptoms suggestive of scabies. Neither Sam’s girlfriend nor his brother is a patient of Dr Itch. In fact, Sam confides, neither has a primary care physician or health insurance.
Network-based vehicle collision detection and simulation

Vehicle driving simulation, collision detection, and collision simulation of rigid bodies are not new concepts in physical-based simulations, but the integration of all these techniques is a challenging and interesting topic. This paper implements a network-based vehicle collision detection and response simulation system that has all the components that are required by a vehicle driving simulation. It supports vehicle-to-scene and vehicle-to-vehicle collision detection and response simulation in real-time required by a human-in-the-loop driving simulation. Additionally, it supports collaborative driving simulations for multiple vehicles in the same virtual environment operated from different physical locations. A network-based collision server is developed to provide consistent and realistic collision response for vehicles that collide. Implementation testing shows that the network-based collision simulation can provide a real-time, realistic and robust system in a network with relatively small time lags, such as a LAN or a city-wide network. The implementation has demonstrated it can support simultaneous collision simulation with up to 32 vehicles operating at 150miles/h in a high speed local area network.Copyright © 2005 by ASME
Magnetic properties and hyperfine interactions in amorphous Fe-Zr alloys

Amorphous Fe/sub x/Zr/sub 100-x/ (20< or =x< or =93) samples were prepared with a high-rate sputtering technique and systematically studied using /sup 57/Fe Moessbauer spectroscopy. Below a critical Fe concentration of x/sub c/roughly-equal45, magnetic order does not occur due to the loss of the Fe moment. Instead, superconductivity with reasonably high transition temperatures appears. Above x/sub c/, a maximum in the magnetic ordering temperature (T/sub c/) was found at x/sub p/approx. =85. At higher Fe concentrations, T/sub c/ decreased and an extrapolation to x = 100 yielded an estimate of T/sub c/ in pure amorphous Fe of about 200 K. Measurements of the effective hyperfine field (H/sub eff/) and the distribution of hyperfine fields (P(H)) were also carried out. The effective hyperfine field was found to increase monotonically with the Fe concentration, unlike the values of T/sub c/, and therefore indicates a monotonically increasing value of the Fe moment. These characteristics are consistent with a localized-moment description of the magnetism in which an antiferromagnetic exchange component appears at high Fe concentrations. The concentration dependence of the electric quadrupole splitting and the isomer shift were also obtained. The former shows a large difference between Fe-rich and Zr-rich samples. In the lattermore » case, the semiempirical model of Miedema and van der Woude was found to be in qualitative agreement with the data.« less
The communication complexity for decentralized evaluation of functions

Abstract Decentralized algorithms can be characterized by successive rounds of message interchanges. In each round, all nodes exchange information and carry out computations. The computations at each node in round i are based on the information available at that node after the communication phase of round i. Therefore, the complexity of the communication requirement is a major determining factor of the performance of a decentralized algorithm. In this paper, we study the communication complexity for decentralized evaluation of functions. We show that for any decentralized algorithm of evaluating a function the number of messages required is at least kN(⌊N 1 k ⌋−1) , where N is the number of nodes in the system and k is the number of rounds of message interchanges. In addition, we classify the functions into three types including fully reducible, partially reducible, and irreducible. We than show that for fully reducible functions the number of bits required for decentralized evaluation is at least kN(⌊N 1 k ⌋−1 )(B+ H) , where B is the number of bits required for representing the initial value of each node and H is the number of bits required for the header and tailer of each message. For irreducible functions, the number of bits required for decentralized evaluation is at least N(N−1)B+kN(⌊N 1 k ⌋−1)H .
The Internal State Scale: replication of its discriminating abilities in a multisite, public sector sample

Objective: The Internal State Scale (ISS) is a self-report instrument that has been validated for discriminating mood states in patients with bipolar disorder. This study a) extends investigation to a multisite public sector sample and b) tests a revised scoring algorithm that formally identifies patients in mixed states. Methods: Eighty-six patients with bipolar disorder from four Veterans Affairs medical centers were assessed in a cross-sectional design. Physician-conducted semi-structured interviews used DSM-IV criteria to identify subjects as meeting criteria for euthymia, mania or hypomania, depression, or mixed state (mania or hypomania plus depression). A revised ISS scoring algorithm independently assigned mood state. Mean subscale scores were analyzed across groups. Receiver-operating characteristic (ROC) curve analysis was conducted to determine optimal algorithm structure. Results: Analysis of mean scores for the ISS subscales replicated original results for Activation, Well-Being, and Perceived Conflict, but indicated differences from the original results for the Depression Index. The ROC curve analysis identified optimal cut-off scores for the revised algorithm. The overall kappa score indicated moderate agreement between ISS and physician ratings of mood state, including mixed states. Limitations: The study used a sample consisting primarily of male veterans. Mood state was assigned by experts using expert clinician diagnosis, not structured interviews. Conclusion: The performance of the ISS in this multisite, public sector sample was similar to the performance in the initial research clinic sample. This finding confirms the validity of the ISS as a discriminator of mood states in bipolar disorder. The development of a revised scoring algorithm makes feasible formal identification of mixed episodes with the ISS.
Policy implications intervention research: Research on the social context for intervention

Intervention research is of significance because the failure or success of particular interventions may have influence on policy and practice. Poorly designed interventions may impede progress in health and safety. Frequently, interventions are based on scientific/technical definitions of occupational health and safety problems but involve intrusion into complex sociotechnical work environments. Intervention research must be built on a solid foundation of social science research. An example of research useful to health and safety intervention is the Gray Institute study of management practices in the chemical industry that was commissioned by OSHA a few years ago. It focused on safety management in chemical manufacturing firms and their contractors, including a survey of managers and contractors and nine intensive case studies of particular plants. The study describes safety management practices in the best firms in the industry. Such research can provide the groundwork for effective safety interventions in the industry, including training and training requirements, experimentation with redefined managerial responsibilities, regulation of contractors, and others. It also suggests the kinds of useful data that might be collected by NIOSH in the normal course of health and safety studies. Finally, it suggests that the interdisciplinary teams currently investigating occupational health and safety should be expanded to include social scientists. © 1996 Wiley-Liss, Inc.
Alfalfa damage from Acyrthosiphon kondoi and economic threshold studies in southern California.

The so-called blue alfalfa aphid (BAA), Acyrthosiphon kondoi Shinji and Kondo, was first found in North America in 1974. It is far more damaging to alfalfa than the pea aphid, A. pisum (Harris) but is easily killed with chemicals used on alfalfa for aphid control. In southern California, a BAA population of 10–12/stem on new regrowth during the Jan., Feb. and Mar. cutting cycles will later reduce yields because natural enemies are not usually present to suppress populations. Damage appears to start at ca. 20 aphids/stem. When the BAA builds up after the crop is one-half or more grown (25–30 cm tall) the plant can withstand 40–50 or more BAA/stem with little or no loss in yield. Damage is most severe when the aphids attack the new regrowth following the winter cuttings. The BAA disappears in early spring when temperatures reach 27°C.
Relations Involving Internal Pressure, Intensity, Mercury Transfer, Cross-Section, and Electrical Conditions in Mercury Vapor Lamps

Internal pressure was measured in two special quartz mercury arcs developed in previous investigations. Numerous curves present the data. Pressure is a function of cross-section, voltage gradient, and current only, and independent of arc length and the mode of cooling. Above two atmospheres pressure increases about 140 mm for unit change in voltage gradient, irrespective of other variables. In the constricted arc, 2 mm in diameter, where the cooler absorbing vapor shell is very thin, intensity at given current strength is quite closely proportional to pressure from a few millimeters up to five atmospheres.With the addition of thermocouple inlets at the mercury surfaces and calibrated measuring tubes, mercury transfer for equal electrode temperatures was measured in the 9 mm arc. The relations are little changed when the cathode is at least 20° to 40° hotter than the anode. Apparently zero at the lowest pressures and voltage gradients, it rises to five gram atoms per faraday from anode to cathode at 5 volts/cm and remains nearly constant up to 25 volts/cm. Current strength is of secondary importance. These conclusions are amply demonstrated by curves. The relative importance of the electron current and the positive ion current under the various conditions studied is briefly discussed.
The influence of gravity on horizontal and vertical vestibulo-ocular and optokinetic reflexes in the rabbit

Abstract The influence of the linear acceleration of gravity on the vertical and horizontal vestibulo-ocular reflexes (VVOR, HVOR) as well as the vertical and horizontal optokinetic reflexes (VOKR, HOKR) has been examined in rabbits. Rabbits were mounted in a biaxial rate table in front of a rear projection tangent screem. Eye movements were measured with a light projection technique. The HVOR, VVOR, HOKR and VOKR were measured in rabbits which were maintained both prone and supine. The gain of the HVOR for the supine orientation was reduced at all frequencies tested (0.01–0.80 Hz). Similarly there was a reduction in the gain of the HOKR. By contrast, the gain of the VVOR in the supine orientation was enhanced over a lower range of frequencies (0.02–0.04 Hz) and reduced at higher frequencies (0.10–0.80 Hz). The gain of the VOKR was not reduced in the supine orientation. The range of eye positions over which compensatory eye movements occured was restricted in the supine orientation. The altered orientation of the medio-laterally polarized hair cells of the utricular maculae with respect to gravity in the supine orientation may cause postural instability and facilitate ‘righting reflexes’. A reduction in the gains of the HVOR, VVOR and HOKR caused by linear accelerations in the sagittal plane during locomotion may decrease automatic postural responses during certain movements in which these automatic postural adjustments would not necessarily be adaptive.
Dopaminergic neurons—Alteration in the kinetic properties of tyrosine hydroxylase after cessation of impulse flow

Abstract Studies in vitro conducted on striatal tyrosine hydroxylase have demonstrated that addition of calcium chelators, such as EGTA, results in an alteration in the kinetic properties of tyrosine hydroxylase which can be completely reversed by addition of calcium to the incubation medium. Inhibition of impulse flow in the nigro-neostriatal pathway by either pharmacological or mechanical techniques causes the isolated striatal tyrosine hydroxylase to behave kinetically like the enzyme treated in vitro with EGTA. Tyrosine hydroxylase, isolated from the striatum of rats in which impulse flow has been interrupted in the dopamine pathways, has an increased affinity for both substrate and pterin cofactor and a reduced affinity for the end-product inhibitor, dopamine. The latter change is most dramatic; the K i of the enzyme for dopamine. increases more than 700-fold. These alterations in the kinetic properties of tyrosine hydroxylase can also be completely reversed by addition of calcium to the incubation medium. In rats with a pharmacological blockade of impulse flow induced by administration of γ-hydroxybutyrate, subsequent administration of dopamine receptor stimulants causes the isolated tyrosine hydroxylase to have properties similar to those observed for the enzyme prepared from untreated rats. Administration of dopamine receptor blockers prevents the dopamine receptor stimulants from altering the kinetic changes in tyrosine hydroxylase induced by a cessation of impulse flow. These data are discussed in terms of the possible role presynaptic receptors and calcium fluxes may play in the short-term regulation of tyrosine hydroxylase.
Design and Characterization of a MEMS Piezoresistive Cochlear-Like Acoustic Sensor

The mammalian cochlea achieves excellent acoustic transduction though the use of mechanical signal processing. The device presented in this paper mimics the structure of the cochlea with a micromachined array of nearly 3000 0.34 μm thick silicon beams suspended between two wafer-high ducts. Piezoresistive strain gauges are incorporated into the beams to produce 38 channels of realtime frequency information. Device mechanical and electrical models are presented. Initial mechanical measurements in air demonstrate good agreement with predicted frequency sensitive and response amplitude. Device sensitivity in air is tentatively measured to be 30 mm/s of beam center velocity response per Pascal of input pressure, corresponding to a predicted piezoresistor sensitivity of 7000 ppm/Pa. This gives an expected achievable resolution of 250 μParms in a 100 kHz band in air. Note that this differs from the intended operating mode of the transducer, which is in fluid over a 20 kHz band.Copyright © 2002 by ASME
A Determination of the Cloud Feedback from Climate Variations over the Past Decade

Estimates of Earth's climate sensitivity are uncertain, largely because of uncertainty in the long-term cloud feedback. I estimated the magnitude of the cloud feedback in response to short-term climate variations by analyzing the top-of-atmosphere radiation budget from March 2000 to February 2010. Over this period, the short-term cloud feedback had a magnitude of 0.54 ± 0.74 (2σ) watts per square meter per kelvin, meaning that it is likely positive. A small negative feedback is possible, but one large enough to cancel the climate's positive feedbacks is not supported by these observations. Both long- and short-wave components of short-term cloud feedback are also likely positive. Calculations of short-term cloud feedback in climate models yield a similar feedback. I find no correlation in the models between the short- and long-term cloud feedbacks.
WirelessHART Routing Analysis Software

Reliability and robustness are critical parameters in choosing a wireless protocol to be used in industry. Nowadays, WirelessHART is the most adopted wireless industrial protocol. However, there are only a few number of analysis tools for industrial networks, specially for WirelesHART, which implies in a lack of information about the health network to its end users. In this paper a software to obtain network data from a WirelessHART network is presented. The developed software allows to identify relevant issues to the verification and maintenance of WirelessHART networks. One of the advantages is the ability to customize the tests, being allowed to evaluate data of most interest for a particular purpose. In a case study, the obtained data allowed to identify the mostly used routes of the network which lead to the identification of bottlenecks.
Brain natriuretic peptide levels do not correlate with acute cellular rejection in De Novo orthotopic heart transplant recipients

Abstract Background The changes in brain natriuretic peptide (BNP) levels after orthotopic heart transplantation have not been previously described. The use of brain natriuretic peptide levels as a surrogate marker for cellular rejection remains controversial, with conflicting data. Methods We prospectively evaluated the potential utility of BNP levels in the first 6 months after transplantation and sought correlation with histologic grade of rejection and hemodynamic status. Results Thirty-five patients and 265 biopsy samples were included in the study. BNP levels did not correlate with histologic grade of rejection. They showed good correlation with central venous pressure and pulmonary capillary wedge pressure. BNP levels were elevated after transplant and showed a steep time-dependent decline. BNP levels correlated with echocardiographically derived indices of diastolic dysfunction. Conclusions BNP levels are not a surrogate marker for rejection in the first 2 months after orthotopic heart transplantation and do not obviate the necessity for endomyocardial biopsy. Whether BNP levels have long-term prognostic significance is unclear and remains the subject of ongoing prospective study.
Modulation of cisplatin sensitivity and accumulation by interferon α‐2A in human squamous carcinoma cell lines

Abstract This study was undertaken to elucidate the mechanism(s) of potentiation of cisplatin (CDDP) cytotoxicity by interferon alpha-2a (IFN alpha-2a) in human squamous carcinoma cell lines SCC-25 and SCC-4. IFN alpha-2a treatment significantly increased the cytotoxicity of CDDP in both cell lines in a dose-dependent manner. In SCC-25 cells, the cytotoxicity of CDDP was increased by about 2- and 4-fold, respectively, by treating the cells with 400 and 800 IU/ml IFN alpha-2a. Sensitivity of SCC-4 cells to CDDP was increased by about 3- and 7-fold, respectively, by 400 and 800 IU/ml IFN alpha-2a treatment. Drug uptake experiments revealed approximately 1.4- to 5-fold higher platinum accumulation in IFN alpha-2a-treated cells as compared to respective controls. Cellular levels of glutathione (GSH) and GSH transferase, which have been suggested to be important determinants of tumor cell sensitivity to CDDP, were not altered by IFN alpha-2a treatment in either of the cell lines. Northern blot analysis showed a moderate increase (about 30-40%) in the level of MT-IIA mRNA by IFN alpha-2a treatment in these cells. Our results suggest that IFN alpha-2a-mediated sensitization of SCC-25 and SCC-4 cell lines to CDDP in vitro may be due to an increase in intracellular platinum accumulation.
Dimensionality and reliability of the Civilian Mississippi Scale for PTSD in a postearthquake community.

This study examines psychometric properties of the Civilian Mississippi Scale for posttraumatic stress disorder when administered in a community survey of 656 persons following the 1989 Loma Prieta earthquake. Internal consistency was lower (Cronbach's α = .73) than for previous analyses of civilian and combat versions of the Mississippi Scale. The analysis produced one strong factor composed of 25 items with regular wording and a second, weaker factor composed of 10 items with reversed wording. Internal consistency was higher when the 10 reversed items were removed (Cronbach's α = .86); the two factors were negatively correlated. Traumatic experiences and psychological distress measures explained more variance in the 25-item factor than in the 35-item scale. Further studies should focus on content analysis and performance of the reversed items.
Reproductive Toxicity Testing: Evaluating and Developing New Testing Systems:

Reproductive toxicity testing systems are used by national and international regulatory agencies. Protocols have not been standardized between agencies or even within certain agencies. Although there have been efforts at standardization, a certain amount of the differences between testing protocols is a reflection of the needs of the particular agency. New developments in in vitro techniques might lead to new test systems, but reproductive function is dependent upon the interaction of various cells and organs that cannot presently be copied in the test tube; this makes whole-animal testing systems a necessity. The present whole-animal models used by the Food and Drug Administration include the 3 segment reproduction studies used for testing drug safety and the multigeneration studies used for food additives. The Environmental Protection Agency has adopted 2 similar versions of a 2-generation study for the Office of Pesticide Programs and the Office of Toxic Substances. The National Toxicology Program, alt...
The use of first-generation tyrosine kinase inhibitors in patients with NSCLC and somatic EGFR mutations

Initial studies with the first-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors gefitinib and erlotinib in patients with non-small cell lung cancer (NSCLC) showed that, although most did not have an objective radiographic response, a minority of patients had dramatic and durable clinical and radiographic responses. The discovery of EGFR mutations in tumours from patients with NSCLC and the association of these mutations with clinical response to gefitinib and erlotinib provided an opportunity to tailor treatment to the mutation profile of the tumour. A number of retrospective reviews and prospective trials have established that gefitinib or erlotinib therapy leads to radiographic responses in approximately 75-80% of patients with NSCLC with EGFR mutations. Although a variety of mutations in EGFR have been identified, the two most common somatic activating EGFR mutations are the LREA deletions in exon 19 and the L858R substitution in exon 21. Together, these mutations make up 85-90% of EGFR mutations. At least two retrospective reviews have indicated a difference in the outcome of patients with different EGFR mutations: after treatment with gefitinib or erlotinib, patients with exon 19 deletions have an increased survival compared with those patients whose tumours have an L858R substitution. These findings remain to be confirmed in prospective studies. Improved understanding of the association of EGFR mutations with clinical outcome may improve the ability of physicians to match treatment to mutation status for patients with NSCLC.
The identification and classification of reactions to sexual harassment

Distinct forms of reactions to sexual harassment were identified in the current study, and a classification scheme was developed based upon those reactions. One hundred forty two male and 100 female upper-division undergraduate management students and 44 working women read 18 randomly ordered scenarios, each of which depicted a woman being exposed to a different form of sexual harassment by a man. For each incident, the subjects were asked to write down what they themselves would do if they were in the woman's place. The resulting 5148 open-ended responses were systematically sorted into 10 classes of reaction types. In addition to assessing the reliability and validity of the classification scheme, the relative frequency of employment of the various classes was examined. Comparisons of the reactions of men and women students and comparisons of the reactions of working women and women students yielded few significant differences.
Treatment of bile acid malabsorption using ileal stem cell transplantation

Purpose: To determine if ileal stem cells transplanted into a segment of jejunum can be used to treat bile acid malabsorption. Methods: In adult Lewis rats, a 15-cm segment of jejunum was isolated with its blood circulation left intact and partially stripped of enterocytes using luminal high-velocity perfusions with 3 mM EDTA solutions. Continuity was restored by anastomosing the proximal and distal gut. Ileal stem cell clusters were harvested from neo-natal Lewis rats and transplanted into these segments. After 4 weeks, rats underwent an ileectomy and the isolated segment was anastomosed in its place. After an additional 4 weeks, a 48 hour stool collection was performed. The engrafted segment was harvested for taurocholate uptake studies, ileal bile acid transporter (IBAT) protein (by immunohistomorphometry) and IBAT mRNA quantitation (by RT-PCR). Data was analyzed by ANOVA/t-test. Rats undergoing ileectomy, jejunectomy or sham operation served as controls. Results: Total bile acid loss in the stool was significantly lower in rats with a neo-ileum compared to rats with an ileectomy (p < 0.004; Fig. 1). Na+-dependent taurocholate uptake was significantly increased in the neo-ileum compared to the jejunum (p < 0.001). IBAT protein signal intensity was significantly higher in the neo-ileum compared to jejunum (p < 0.001). IBAT mRNA amounts were significantly higher (p < 0.004) than in the jejunum however comparable to the ileum. Conclusion: Ileal stem cells were used to establish a new zone of active bile acid uptake and IBAT expression in a jejunal segment. This neo-ileum eliminated loss of bile acids in the stool after ileectomy. This is the first time intestinal stem cell transplantation has been shown to correct a clinical malabsorption syndrome. Download high-res image (132KB) Download full-size image
Hydration Free Energies by Energetic Partitioning of the Potential Distribution Theorem

In the quasichemical theory of molecular solutions, the hydration free energy is spatially partitioned in a three-step thermodynamic process: cavity formation, solute insertion into the cavity, and relaxation of the cavity constraint. In the alternative local molecular field theory that focuses on the relationship of fluid structure and forces, the interaction energies are directly partitioned into local and far-field components; a restructured local potential incorporates information from the far-field interactions at the mean-field level. Here the quasichemical and local molecular field theories are related via energetic partitioning of the potential distribution theorem free energy. The resulting theory leads to a free energy division in which the local contribution requires direct evaluation, but the far-field component can be accurately estimated at the Gaussian level. A numerical approach for computing hydration free energies is developed that employs interaction energy distributions from several sampling states. Classical model problems of nonpolar, polar, and ionic hydration are presented to illustrate the theory. Extensions of the theory for estimating free energies at the quantum level are also discussed.
Acute progesterone and 17β-estradiol modulation of luteinizing hormone secretion by pituitaries of cycling rats superfused in vitro

During the rat estrous cycle there are marked changes in the concentrations of serum 17 beta-estradiol (E2) and progesterone. The objective of the present study was to examine the acute effects of E2 and progesterone on isolated pituitaries obtained at 1230 h at each stage of the 4-day cycle. At time zero, single quartered anterior pituitaries were placed in a chamber and superfused at 0.5 ml/min with medium 199 with or without steroids for 360 min; sequential 10-min effluent samples were collected. LHRH (10 ng/ml) was administered as two successive 10-min pulses at 120 and 240 min. The proestrous and the diestrous-II pituitaries in vitro exhibited the characteristic LHRH self-priming response: an increased LH secretory response to a second pulse of LHRH in both the absence and presence of steroids in the superfusion medium; however, the magnitude of the response to the initial pulse of LHRH was reduced significantly when E2 (50 pg/ml) was present. The presence of progesterone (50 ng/ml) resulted in a marked augmentation of the LH secretory response to the first pulse of LHRH; when both E2 and progesterone were included in the superfusion medium, the stimulatory effect of progesterone was reduced. The progesterone augmentation of LHRH-induced LH secretion was present after 60 min of steroid exposure in vitro but was not demonstrable after only 10 min of exposure. Cycloheximide inhibited the progesterone augmentation and the LHRH self-priming without affecting the LH secretory response to the initial LHRH pulse in the absence of steroid. Progesterone augmentation was not observed on estrus and diestrous-I. The presence of E2 in the medium, however, resulted in a significant decrease in the response to the first pulse of LHRH for pituitaries from either estrus or diestrous-I. These data 1) demonstrate that E2 by itself suppresses LHRH-induced LH secretion by the proestrous pituitary and 2) provide proof for a direct stimulatory action of progesterone, in the absence of E2, on the proestrous pituitary and suggest a positive feedback role for progesterone during the preovulatory LH surge. (Endocrinology 108: 413, 1981)
New approximations and collocation schemes in the finite cloud method

The finite cloud method (FCM) [Int. J. Numer. Methods in Eng. 50(10) (2001) 2373] is a meshless technique combining a fixed kernel approximation of the unknown function(s) with a point collocation discretization of the governing PDEs. The meshless approximation and the collocation discretization are the two major steps in FCM. Since the quality of the numerical solution depends on the quality of the meshless approximation functions or shape functions and the discretization scheme employed, in this paper, we propose several improvements to the construction of meshless shape functions and compare several collocation schemes within the framework of the FCM. The improvements to the shape functions are combined with various collocation schemes to solve several 2-D Poisson and elastostatic examples. The convergence characteristics of the collocation schemes are studied. The accuracy of the collocation schemes with a scattered point distribution is also investigated.
Neptune may have polar rings

Perturbations from Neptune's highly inclined satellite Triton can maintain rings passing nearly over Neptune's poles. These hypothetical polar rings are nearly perpendicular to Triton's orbit as well, and lie within several degrees of the plane of Voyager II's trajectory through the Neptunian system. Polar rings can coexist with equatorial rings at different radii. A randomly oriented torus of debris around Neptune has a probability of several percent to settle into a polar ring. Voyager II stands a significant chance of encountering a polar ring.
School Reentry Following Traumatic Brain Injury

Successful school reentry following traumatic brain injury (TBI) is critical to recovery. Physical, cognitive, behavioral, academic, and social problems can affect a child's school performance after a TBI. However, early intervention has the potential to improve child academic outcomes and promote effective coping with any persistent changes in functioning. The purpose of this article is to review the topic of school reentry after a childhood TBI. The authors describe 4 essential principles to planning a positive reentry to school: assessment, multidisciplinary teaming, facilitation of peer interactions, and planning for the provision and withdrawal of support. The authors delineate a sequence of steps for promoting school reentry and review existing school reentry programs. The authors also discuss barriers to the school reentry process and possible solutions. The article concludes with a case study that highlights some of the challenges of school reentry and the benefits of using interactive videoconfer...
Functional differences between neurotransmitter binding sites of muscle acetylcholine receptors

A muscle acetylcholine receptor (AChR) has two neurotransmitter binding sites located in the extracellular domain, at αδ and either αe (adult) or αγ (fetal) subunit interfaces. We used single-channel electrophysiology to measure the effects of mutations of five conserved aromatic residues at each site with regard to their contribution to the difference in free energy of agonist binding to active versus resting receptors (ΔGB1). The two binding sites behave independently in both adult and fetal AChRs. For four different agonists, including ACh and choline, ΔGB1 is ∼−2 kcal/mol more favorable at αγ compared with at αe and αδ. Only three of the aromatics contribute significantly to ΔGB1 at the adult sites (αY190, αY198, and αW149), but all five do so at αγ (as well as αY93 and γW55). γW55 makes a particularly large contribution only at αγ that is coupled energetically to those contributions of some of the α-subunit aromatics. The hydroxyl and benzene groups of loop C residues αY190 and αY198 behave similarly with regard to ΔGB1 at all three kinds of site. ACh binding energies estimated from molecular dynamics simulations are consistent with experimental values from electrophysiology and suggest that the αγ site is more compact, better organized, and less dynamic than αe and αδ. We speculate that the different sensitivities of the fetal αγ site versus the adult αe and αδ sites to choline and ACh are important for the proper maturation and function of the neuromuscular synapse.
Evidence that the L -Asparaginase Activity of Guinea Pig Serum is responsible for its Antilymphoma Effects

THE inhibitory action of guinea pig serum on the cells of three transplantable mouse and rat lymphomas in vivo was described some years ago in papers from this Laboratory1,2. In a continuation of this work, evidence has now been found that the L-asparaginase activity of guinea pig serum is responsible for the antilymphoma effect. The evidence has been obtained in two ways: first, by a study of the induction of resistance to guinea pig serum by 6C3HED cells grown in tissue culture; and secondly, by a direct comparison of L-asparaginase activity in various preparations of guinea pig serum with their tumour inhibitory properties.
Measuring Diversity in Police Agencies

Despite numerous studies on minority and female integration into police agencies, the use of diversity indices to benchmark and assess changes in the ethnic and racial composition of police workforces has been limited. This study applies the Simpson, McIntosh, and measure of variation indices to data on the New York City Police Department's police and civilian workforces to obtain workforce diversity measurements. Pearson and Spearman correlation analyses show that the 3 indices produce diversity measurements that are consistent with one another. Although the indices produce similar scores, the Simpson index is more efficient at measuring diversity and less sensitive to the number of ethnic or racial categories used by the New York City Police Department in comparison to the McIntosh and measure of variation indices.
Laminated composite shells under axially symmetric dynamic loadings

Abstract In this paper, the classical method of separation of variables, combined with the Mindlin-Goodman procedure for treating time-dependent boundary conditions and/or dynamic external loadings, is extended to investigate the dynamic response of laminated composite shells. The validity of this method applied to laminated composite shells under axially symmetric loadings is first established by showing that the principal modes of free vibration are orthogonal. The formal solution of the general forced vibration problem is thus obtained. By means of the result, a specific example is worked out for a simply supported laminated shell subjected to suddenly applied uniform dynamic pressure. The dynamic response of radial displacement, w , and bending moments, M x , and M θ , are compared with the corresponding quantities obtained statically. It is observed that dynamic values are about two to two and a half times the corresponding static values, for the materials and stacking sequences selected in the example problems.
Spectroscopic investigations of the binding mechanisms between antimicrobial peptides and membrane models of Pseudomonas aeruginosa and Klebsiella pneumoniae

CD spectroscopy was used to investigate the interactions of a series of synthetic AMPs with LPS isolated from Pseudomonas aeruginosa and Klebsiella pneumoniae, as well as with various phospholipids to better approximate the chemical composition of the membranes of these two strains of Gram-negative bacteria. This investigation was conducted in order to probe how the contributions of key physicochemical properties of an AMP vary in different regions of the membranes of these two bacteria. The conclusions from this study are as follows. (1) The binding interactions between the AMP and the membranes are defined by the complementarity of delocalization of positive charge density of the basic amino side chains (i.e., electrostatics), molecular flexibility of the peptide backbone, and overall hydrophobicity. (2) The binding interactions of these AMPs to LPS seem to be predominantly with the lipid A region of the LPS. (3) Incorporation of phospholipids into the LPS containing SUVs resulted in dramatic changes in the conformational equilibrium of the bound AMPs. (4) For the LPS-phospholipid models of Pseudomonas aeruginosa, delocalization of the side chain positive charge plays a major role in determining the number of conformers that contribute to the binding conformational equilibrium. This relationship was not observed for the models of the outer and inner membranes of Klebsiella pneumoniae.
Microeconomic theory of chemical production processes: application to aqueous VOC air stripping operations

Abstract A novel microeconomic formalism for chemical processes is applied to air stripping of harmful volatile organic compounds (VOCs) from aqueous streams in a conventional packed tower. A simplified conceptual process model is combined with techno-economic aggregation rules to obtain an engineering production function, which relates process inputs (capital, material, labor, and energy) to output (stripped water flow rate). Process relationships determine column length and diameter required to achieve a specified VOC percent recovery from an aqueous stream of given composition and flow rate. Total capital is determined using a defined capital unit (1 capital unit=10 foot of 6-inch schedule 40 carbon steel welded pipe=$122, Jan. 1990) to put all installed capital equipment on the same basis and multiplying by 3.37 to account for the necessary plant infrastructure. Process labor is obtained from an empirical correlation, which relates workerhours to mass throughput. Simulations were made for four systems comprised from each of two representative random packings (i.e. 25-mm plastic Pall rings and 25-mm ceramic Raschig rings) and two model VOCs (i.e. 1,2-dichloroethane and trichloroethylene). Several examples are given, and process, technical and economic analyses of the results are presented. Two-dimensional (capital–energy) optimization was effective in determining the least cost combination of inputs for a plant to produce a specified output of stripped water. Furthermore, conventional economic models (e.g. Cobb–Douglas model) and associated methods (e.g. linear programming) were shown to be ineffective for air stripping plant design and optimization. Moreover, increasing returns to scale with economies of scale (declining long-run average cost) are prevalent.
Further Studies of the Effects on Myocardial Energy Utilization Elicited by Nitroglycerin

Since sympathetic stimulation could play an important part in the short term attacks of angina pectoris, the effects of nitroglycerin on the myocardial response to levarterenol were investigated. Levarterenol infusions directly increased the isometric systolic tension (IST) developed by the cardiac muscle. Nitroglycerin had no apparent direct effect on this increase in IST either in the normal heart or in the heart following partial coronary ligation. In experiments in which IST was measured with a lever system adjusted to the end-diastolic length and tension occurring just prior to the contraction, nitroglycerin was found to have an indirect depressant effect on the levarterenol response. This decrease in contractility was shown to be secondary to a decrease in hemodynamic work load elicited by nitroglycerin. It is suggested that the chief effect of nitroglycerin in the relief of angina pectoris is due to this agent's ability to decrease a work load imposed on the myocardium by sympathetic stimulation.
The Non-Existence of a Principle of Natural Selection

The theory of natural selection is a rich systematization of biological knowledge without a first principle. When formulations of a proposed principle of natural selection are examined carefully, each is seen to be exhaustively analyzable into a proposition about sources of fitness and a proposition about consequences of fitness. But whenever the fitness of an organic variety is well defined in a given biological situation, its sources are local contingencies together with the background of laws from disciplines other than the theory of natural selection; and the consequences of fitness for the long range fate of organic varieties are essentially applications of probability theory. Hence there is no role and no need for a principle of the theory of natural selection, and any generalities that may hold in that theory are derivative rather than fundamental.