cssi/SciSciGPT-SciSciNet huggingface dataset:
Modelling the vertical distribution of Prochlorococcus and Synechococcus in the North Pacific Subtropical Ocean.

Summary A simple model was developed to examine the vertical distribution of Prochlorococcus and Synechococcus ecotypes in the water column, based on their adaptation to light intensity. Model simulations were compared with a 14-year time series of Prochlorococcus and Synechococcus cell abundances at Station ALOHA in the North Pacific Subtropical Gyre. Data were analysed to examine spatial and temporal patterns in abundances and their ranges of variability in the euphotic zone, the surface mixed layer and the layer in the euphotic zone but below the base of the mixed layer. Model simulations show that the apparent occupation of the whole euphotic zone by a genus can be the result of a co-occurrence of different ecotypes that segregate vertically. The segregation of ecotypes can result simply from differences in light response. A sensitivity analysis of the model, performed on the parameter α (initial slope of the light-response curve) and the DIN concentration in the upper water column, demonstrates that the model successfully reproduces the observed range of vertical distributions. Results support the idea that intermittent mixing events may have important ecological and geochemical impacts on the phytoplankton community at Station ALOHA.
Transient analysis of lossless transmission lines

The method of characteristics provides a simple analytic solution for the transient analysis of a uniform, lossless transmission line. The interpretation of this solution in terms of equivalent network of the input and output behavior of the transmission line leads to an efficient algorithm which yields not only the input and output responses but also the incident and reflected waves. This method is superior in both speed and accuracy to the familiar method of integrating the differential equations that describe a lumped LC model of the line; but it is not applicable to lossy lines.
Chronic Hypoxia Differentially Regulates α1-Adrenergic Receptor Subtype mRNAs and Inhibits α1-Adrenergic Receptor–Stimulated Cardiac Hypertrophy and Signaling

Background After myocardial ischemia and/or infarction, surviving cardiac myocytes in and around the injured zone develop hypertrophy to compensate for the loss of contractile units due to myocyte injury and death. One of the factors that may be involved in the development of hypertrophy after ischemic injury is norepinephrine (NE), an agent that induces hypertrophy of cardiac myocytes through the α1-adrenergic receptor (AR). It is not known, however, whether hypoxia, a major component of ischemia, has any direct effect on NE-stimulated hypertrophy. Therefore, we sought to determine whether chronic hypoxia could alter NE-stimulated hypertrophy and if so, whether this alteration was related to α1-AR–mediated signaling and α1-AR changes at both the protein and mRNA levels. Methods and Results We developed a model of chronic hypoxia in cultured neonatal rat cardiac myocytes in which myocytes were exposed to 1% oxygen for 72 hours. Initially, we observed that chronic hypoxia inhibited NE-stimulated hypertroph...
Ventilatory complications of carbon dioxide laser laryngeal surgery.

Abstract Study Objective: To evaluate complications associated with ventilatory techniques accompanying endolaryngeal carbon dioxide laser surgery. Design: Retrospective survey of the Society of Academic Anesthesia Chairmen. Setting: Operating room at an urban medical center. Patients: Data from 15,701 patients were analyzed. Measurements and Main Results: Twenty-six percent of patients were ventilated with Venturi jet ventilation and the rest through an endotracheal tube. Reported complications were classified as ventilation related and ventilation unrelated, as well as by severity. A total of 49 complications occurred in the Venturi jet group (1.2%). Of these complications, 24 were ventilation related (0.58%) and 18 were serious or life threatening (0.43 %). There were no deaths in this group. Ventilation through an endotracheal tube was associated with a lower frequency of overall complications (0.36%), ventilation-related complications (0.15%), serious or life-threatening complications (0.15%), and serious or life-threatening ventilation-related complications (0.11%) (p Conclusions: No clear choice of ventilatory technique is supported by this survey, but teamwork and experience give the best results.
Using Risk Assessment to Inform Sentencing Decisions for Nonviolent Offenders in Virginia

Virginia has abolished parole and adopted truth-in-sentencing guidelines for persons convicted of felonies. As part of this reform, the Virginia Criminal Sentencing Commission developed a method for diverting 25% of nonviolent, prison-bound offenders into alternative sanction programs using risk assessment to identify the lowest risk offenders. This article describes an evaluation of the effectiveness of this instrument, used by judges at the time of sentencing. It serves to advance an understanding of the factors associated with recidivism and the policy implications of using risk assessment to divert offenders from incarceration at a time when states are facing fiscal challenges.
Status of Fire Boom Performance Testing

Abstract Most response plans for in situ burning of oil at sea call for the use of a fire-resistant boom to contain the oil during a burn. Presently, there is no standard method for the user of a fire-resistant boom to evaluate the anticipated performance of different booms. The American Society for Testing and Materials (ASTM) F-20 Committee has developed a draft Standard Guide for In Situ Burning of Oil Spills On Water: Fire-Resistant Containment Boom; however, the draft provides only general guidelines and does not specify the details of the test procedure. Significant advances have been made in the past three years in implementing the guidelines in the draft standard. Two series of tests, one using diesel fuel and one using propane, have been conducted to evaluate the protocol for testing the ability of fire-resistant booms to withstand both fire and waves. A brief description and comparison of these tests is presented along with a discussion of the strengths and weaknesses of the use of each fuel and some issues identified in the tests.
Dosimetric considerations in treating mediastinal disease with mantle fields: Characterization of the dose under mantle blocks

While the rationale for using mantle fields is well understood and the prescription of these fields is straightforward, the underlying complexity of the dose distributions that result is not generally appreciated. This is especially true in the choice of lung block design, which affects the dose to both the target volume as well as to the normal lung tissue. The key to the design of optimal lung blocks is the physician`s perception of the complex relationship between the geometric and dosimetric aspects of heavily modified fields, as well as how the physical and anatomical properties of the target volume and the shape of the patient`s lungs relate to the images visualized on simulator films. Depth doses and cross-beam profiles of blocks ranging in width from 1 cm to 10 cm were taken using an automated beam scanning system. These data were then converted to {open_quotes}shadow fields.{close_quotes} Shadow fields behave quite similarly to small, open fields in terms of x-ray-light field congruence, flatness, symmetry, and penumbra. There is a 2-3 mm rim between the edge of the block and the point at which it becomes nominally effective. The dose at the center of a block, which gives the normalization of themore » shadow fields, is given by a block transmission factor (BTF), which produces results in excellent agreement with measurements over a wide variety of block sizes and tissue depths. The radiation dose under shielding blocks can be considerably higher than expected, and care must be exercised when drawing blocks close to critical structures. The effects of blocks can be described in terms of normalized shadow fields, which behave similar to narrow, open fields, but with a divergence characteristic of their position relative to the radiation source. The normalization value for these fields, which gives the relative dose under the block, can be obtained from a straightforward analytical expression, the BTF. 33 refs., 9 figs., 4 tabs.« less
Impurity Resistivity under Thermalized Condition

The standard impurity resistivity based upon the force-balance equation is derived with use of the method of closed-time-path Green’s functions. In this the effects from both the noncommutability of the center of mass fluctuations at different times and the exact noncannonical commutation relations between the coordinates and momentum of relative electrons are considered. In the presence of a short momentum-conserving inelastic scattering time due to electron-electron interaction, fast thermalization among charge carriers can be achieved. Under this condition, the (thermalized) impurity resistivity will have different form than the standard impurity resistivity and it is practically given by the lowest order electron-impurity term in the force balance equation. We also demonstrate that this conclusion is consistent with results based upon the Boltzmann equation in a relaxation time approximation.
Telomerase-mediated lifespan extension of human bronchial cells does not affect hexavalent chromium-induced cytotoxicity or genotoxicity

Hexavalent chromium (Cr(VI)) is a metal of increasing public health concern, as exposure to it is widespread and it is a well-established cause of human bronchial carcinomas and fibrosarcomas. The water-insoluble Cr(VI) salts are potent carcinogens compared to the water soluble salts; yet the genotoxic mechanisms of both may be mediated by soluble Cr(VI) ions. Currently, these mechanisms are poorly understood. Emerging evidence suggests that initial cell culture models used to study the general toxicity of Cr(VI) may be suboptimal for investigating mechanisms specific to human bronchial cells. Accordingly, we have developed a new model system of human bronchial cells by introducing hTERT, the catalytic subunit of human telomerase, into primary human bronchial fibroblasts (PHBF). We have isolated a stable, clonally derived cell line, WHTBF-6, that demonstrate reconstitution of telomerase activity and maintenance of telomere lengths with increasing culture age. WHTBF-6 has been characterized as having an extended in vitro lifespan, a normal growth rate, a normal diploid karyotype that is maintained over time, and exhibits serum-dependent contact-inhibited anchorage-dependent growth. Moreover, we find that both particulate and soluble hexavalent chromium induce a pattern and degree of cytotoxicity and clastogenicity in WHTBF-6 that is similar to the parental PHBF cells. Because telomerase does not compromise growth or the response to Cr(VI), our results indicate that this is an excellent system for studying the mechanisms of Cr(VI) and potentially other carcinogens implicated in the development of lung cancer.
Exact Aggregation With Linear Programming Models—A Note on the Sufficient Conditions Proposed by R. H. Day: Reply

Richard H. Day's 1963 article [1] on exact aggregation in linear programming models has now become an obligatory reference for research workers in the field of aggregate linear programming. Day presented sufficient conditions for using-without loss of precision-a single aggregate model to define the optimum combination of productive activities for a group of firms, rather than separate models for each firm.' The aim of this note is to show how at least one of these conditions-required particularly for obtaining from the aggregate models unbiased results for the unknowns of the dual problemis not necessary. More precisely, the condition in question is not an additional condition with respect to those remaining, in that it is always respected if the others are already respected. From a
Distribution of Conformations Sampled by the Central Amino Acid Residue in Tripeptides Inferred From Amide I Band Profiles and NMR Scalar Coupling Constants

The conformational preference of individual amino acid residues in the unfolded state of peptides and proteins is the subject of a continuous debate. Research has mostly been focused on alanine, owing to its abundance in proteins and its relevance for the understanding of helix ↔ coil transitions. In the current study, we have analyzed the amide I band profiles of the IR, isotropic and anisotropic Raman, and VCD profiles of trialanine in terms of a conformational model which, for the first time, explicitly considers the entire ensemble of possible conformations rather than representative structures. The distribution function utilized for a satisfactory simulation of the amide I band profiles was found to also reproduce a set of five J coupling constants reported by Graf et al. (Graf, J.; et al. J. Am. Chem. Soc. 2007, 129, 1179). The results of our analysis reveal a PPII fraction of ∼0.84 for the central alanine residue, which strongly corroborates the notion that alanine has a very high PPII propensity, ...
Local E-optimality conditions for trajectory design to estimate parameters in nonlinear systems

This paper develops an optimization method to synthesize trajectories for use in the identification of system parameters. Using widely studied techniques to compute Fisher information based on observations of nonlinear dynamical systems, an infinite-dimensional, projection-based optimization algorithm is formulated to optimize the system trajectory using eigenvalues of the Fisher information matrix as the cost metric. An example of a cart-pendulum simulation demonstrates a significant increase in the Fisher information using the optimized trajectory with decreased parameter variances shown through Monte-Carlo tests and computation of the Cramer-Rao lower bound.
COMPUTED TOMOGRAPHIC IMAGING OF THE EQUINE HEAD

The head from three horses euthanized due to diseases unrelated to the head and neck was imaged using computed tomography (CT). Gross cross-sectional slices of equine head #1 and skeleton of equine head #2 were compared with the CT images of the three equine heads to identify normal structures of the cranium, brain, paranasal sinuses, nasal cavity, and teeth. Labeled transverse CT images of the equine head are presented sequentially as a reference for normal anatomy.
Synthesis of B vitamins by excised parts of white lupine seedlings grown in sterile culture.

Abstract In this investigation it has been found that excised roots, hypocotyls, and epicotyls of White lupine seedlings synthesize thiamine, riboflavin, and niacin when grown in sterile cultures. Oxygen is necessary for this synthesis.
Microphase separation in block copolymers.

We introduce a microscopic model for the phase separation in block copolymers and carry out Monte Carlo simulations in two dimensions. We find that the equilibrium structure function satisfies a scaling relation with D eq , the thickness of the microdomains. We also find that D eq ∼Nθ, where N is the chain length and θ=1/2 in the weak-segregation limit, in agreement with calculations in a cell-dynamics model. This suggests that the microscopic and the continuum models of block copolymers are in the same universality class
Performance of MEPDG Dynamic Modulus Predictive Models for Asphalt Concrete Mixtures: Local Calibration for Idaho

AbstractThe mechanistic-empirical pavement design guide (MEPDG) is the research version of the newly released DARWin-ME software by AASHTO. MEPDG includes two models for Levels 2 and 3 hot-mix asphalt (HMA) dynamic modulus (E*) predictions. The two models are NCHRP 1-37A and NCHRP 1-40D. The primary difference between the two is the binder stiffness parameter; viscosity or shear modulus. Moreover, MEPDG includes three levels for binder stiffness characterization: viscosity for Level 1 conventional binders, shear modulus for Level 1 superpave binders, and default values for Level 3. The influence of the binder characterization input level on the performance of the MEPDG E* predictive models is evaluated in this paper. To calibrate the models for Idaho, 27 HMA mixtures commonly used in Idaho were investigated. Results showed that the performance of the investigated models varied based on the temperature and the binder characterization method. The NCHRP1-37A E* model with MEPDG Level 3 binder inputs yielded ...
First steps towards a social learning analytics for online communities of practice for educators

Learning analytics has the potential to provide actionable insights for managers of online communities of practice. Because the purposes of such communities and the patterns of activity that might further them are diverse, a wider range of methods may be needed than in formal educational settings. This paper describes the proposed learning analytics approach of the U. S. Department of Education's Connected Educatorsproject, and presents preliminary applications of social network analysis to the National Science Teachers Association Learning Center as an illustration.
The Pettis integration of a perturbed wave equation

In this paper, we investigate the integrability of the vector field of the initial-value problem associated with certain nonlinear wave equations. This vector field involves translations and as such is not a strongly continuous or even strongly measurable L ∞ -valued function. It is shown that such a vector field, although not generally Pettis integrable, does turn out to be so in an important situation. We then indicate how this result can be used to obtain pseudo-solutions of the initial-value problem.
Posttransplant improvement in heart rate variability correlates with improved quality of life.

A prospective evaluation of 37 kidney and 20 kidney-pancreas transplant recipients was conducted to assess the relationship between pre-to posttransplant changes in heart rate variability (HRV) and quality of life (QoL). Assessments of 24-hour interbeat variability (pNN50 and rMSSD, SDNN, SDANN) and power spectral analysis of total, low (sympathetic), and high (parasympathetic) frequency components of HRV were performed. The Sickness Impact Profile was used to assess three dimensions of QoL (physical, psychosocial, and total functioning) prior to and at 6 months following transplantation. Changes in vagally mediated time domain measures of HRV were related to changes in physical and total functioning. Stronger correlations occurred between biobehavioral measures in kidney-pancreas recipients, with the strongest relationships occurring between changes in HRV frequency domain measures and changes in physical functioning. Findings indicate that changes in HRV and QoL are related, suggesting that intervention...
Interaction sites of the C-terminal region of the cGMP phosphodiesterase inhibitory subunit with the GDP-bound transducin alpha-subunit.

In the present report, the region of interaction between the GDP-bound alpha-subunit of transducin (alphat.GTP) and the cGMP phosphodiesterase inhibitory gamma-subunit (Pgamma) has been studied. It is widely accepted that the alphat.GTP is the active form of transducin and that the GDP-bound transducin alpha-subunit (alphat. GDP) is the inactive form. We have reported previously that the binding region of the C-terminal of Pgamma on alphat.GTP is in a region between the exposed face of the alpha3 and alpha4 helices of alphat.GTP [Liu, Arshavsky and Ruoho (1996) J. Biol. Chem. 271, 26900-26907]. We now report that N-[(3-[125I]iodo-4-azidophenylpropionamido-S-(2-thiopyridyl) ]cysteine ([125I]ACTP)-derivatized Pgamma (at Cys-68) reversibly undergoes a unique disulphide exchange of the radioiodinated moiety N-(3-[125I]iodo-4-azidophenylpropionamido)cysteine ([125I]APC) from Cys-68 of Pgamma to alphat.GDP but not to the guanosine 5'-(gamma-thio)-triphosphate (GTP[S])-bound transducin alpha-subunit (alphat-GTP[S]). The specificity of the interaction was demonstrated by the fact that exchange was protected by the functionally active Cys-68-->Ala Pgamma mutant, and by pretreatment of the alphat.GDP with the betagamma-subunit of transducin. Chemical cleavage and amino acid sequencing demonstrated that the [125I]ACTP-derived Pgamma specifically transferred the [125I]APC group to Cys-250 and Cys-210 of alphat.GDP. These data indicate that the C-terminal region (especially Cys-68-Trp-70) of Pgamma interacts with alphat. GDP on the exposed interface between alpha2/beta4 and alpha3/beta5 of the alpha-subunit of transducin. Disulphide exchange was also observed with the alpha-subunit of holotransducin but this was only approx. 60% of that of pure alphat.GDP. The variation in the binding pattern between alphat.GDP and alphat.GTP with the C-terminal region of Pgamma may contribute to the functional difference between the GDP- and GTP-bound states.
Packet drop avoidance for high-speed network transmission protocol

As network bandwidth continues to grow and longer paths are used to exchange large scientific data between storage systems and GRID computation, it has become increasingly obvious that there is a need to deploy a packet drop avoidance mechanism into network transmission protocols. Current end-to-end congestion avoidance mechanisms used in transmission control protocol (TCP) have worked well on low bandwidth delay product networks, but with newer high-bandwidth delay networks they have shown to be inefficient and prone to unstable. This is largely due to increased network bandwidth coupled with changes in Internet traffic patterns. These changes come from a variety of new network applications that are being developed to take advantage of the increased network bandwidth. This paper examines the end-to-end congestion avoidance mechanism and perform a step-by-step analysis of its theory. In addition we propose an alternative approach developed as part of a new network transmission protocol. Our alternative protocol uses a packet drop avoidance (PDA) mechanism built on top of the maximum burst size (MBS) theory combined with a real-time available bandwidth algorithm.
Quantitative evaluation of color measurements: I. Triaxial stereoscopic scatter plots

Abstract Too frequently, geologists collect many color measurements but do little with them quantitatively. However, the three parameters of Munsell colors (hue, lightness and chroma) can usefully be plotted on 3D stereoscopic scatter plots (i.e., XYZ graphs that use stereoscopic depth to portray the third dimension). Graphical presentation of all three variables in one diagram permits quick and easy visual comparisons of ranges, clustering and absolute values of colors of different formations, soils or rock types. Although the subject of sedimentary colors seems too complex to talk of diagnostic color fields for specific depositional environments, examples drawn from around the world show how easily stereoplots can demonstrate narrow color ranges associated with some soil types and with some facies in specific formations.
Tire Traction on Snow-Covered Pavements

A generalized theory for the traction of a pneumatic tire on a snow-covered pavement is presented.
Helen Hart, remarkable plant pathologist (1900-1971).

Helen Hart was a Professor of Plant Pathology at the University of Minnesota from 1924 until retirement in 1966. Born in Janeville, Wisconsin, she died at Grants Pass, Oregon. Her scholarly research concentrated on wheat stem rust to understand host pathogen relationships and to develop rust–resistant cultivars. She did not teach formal courses but was heavily involved in making seminars a vital part of instruction, in teaching languages needed for graduate studies, and as an informal advisor for most rust research theses. She had common sense, excellent scientific judgment, and sound instincts on personnel matters that served the department well. A talented science writer, Hart served as editor of hundreds of theses and departmental manuscripts for publication. Her writing and editing skills were used as associate editor of Phytopathology for two years and as editor-in-chief from 1944–1951. A strong advocate of The American Phytopathological Sociecty, Helen Hart served on Council for 12 years and as Pres...
Commentary: Epidemiology and the pharmaceutical industry: an inside perspective

at the FDA. Lancet 2004;364:1995–96. 59 Topol EJ. Failing the public health Rofecoxib, Merck, and the FDA. N Engl J Med 2004;351:1707–9. 60 Last JM. Guidelines on ethics for epidemiologists. Int J Epidemiol 1990;19:226–29. 61 Neutra RR, Cohen A, Fletcher T, Michaels D, Richter ED, Soskolne CL. Toward guidelines for the ethical reanalysis and reinterpretation of another’s research. Epidemiology 2006;17:335–38. 62 Prineas RJ, Goodman K, Soskolne CL et al. Findings from the American College of epidemiology’s survey on ethics guidelines. Ann Epidemiol 1998;8:482–89. 63 Soskolne CL, Sieswerda LE. Implementing ethics in the professions: examples from environmental epidemiology. Sci Eng Ethics 2003;9:181–90. 64 Soskolne CL. Epidemiology: questions of science, ethics, morality, and law. Am J Epidemiol 1989;129:1–18. 65 Olsen J. Good epidemiological practice: proper conduct in epidemiologic research. International Epidemiological Association, 2007. 66 Davey Smith G. Reflections on the limitations to epidemiology. J Clin Epidemiol 2001;54:325–31. 67 Vallance P. Developing an open relationship with the drug industry. The Lancet 2005;366:1062–64.
Carcinoma of the thyroid in black patients.

In the period from January 1,1976 to December 31, 1988, we reviewed the charts of 33 patients treated for carcinoma of the thyroid at Howard University Hospital. The three non-black patients (two Whites and one Pakistani) were excluded from the study. There were 19 females and 11 males. Of the 30 cases elevated, 10 were papillary, 7 were follicular variant of papillary, 8 were follicular, 3 were undifferentiated (anaplastic), and 2 were medullary. Ten patients had either distant metastasis (Hoffman, South Med J 80:741, 1987) or locally advanced disease in the neck (Woolner et al., Am J Surg 102:354, 1961.) at the time of diagnosis. The treatment of these lesions depended on, among other variables, the cell type, the extent of the lesion, and the personal preference of the attending surgeon. Carcinoma of the thyroid remains an uncommon lesion in Black patients. Because of its rarity, the diagnosis may often be delayed and, as a result, patients may first come to attention with a more advanced stage of this disease. To prevent this occurrence, a high index of suspicion must be maintained for all thyroid nodules, and appropriate diagnostic steps taken. Diagnostic and treatment options are discussed. © 1992 WiIey-Liss, Inc.
Prevention of fusion and leakage in freeze-dried liposomes by carbohydrates

Abstract The ability of various carbohydrates to prevent leakage of a small, water-soluble marker from unilamellar liposomes during freeze-drying has been investigated and compared with the ability of trehalose to prevent such leakage. Mechanisms of the stabilizing effect of the carbohydrates have also been studied. While the ability of the sugars to prevent lipid mixing during freeze-drying is related to their ability to prevent leakage more sugar is required for prevention of leakage than for prevention of lipid mixing. The mass ratio of carbohydrate:lipid (rather than the molarity of the solution) is the important parameter for prevention of lipid mixing and leakage. Calorimetric results suggest that it is the ability of trehalose to prevent phase separation during drying and phase transitions during rehydration that accounts for the stabilizing effect of this carbohydrate.
Phase I Evaluation of Prolonged-Infusion Gemcitabine With Irinotecan for Relapsed or Refractory Leukemia or Lymphoma

PURPOSE: To estimate the maximum-tolerated duration of infusion of gemcitabine at 10 mg/m2/min in combination with irinotecan at 40 mg/m2 daily for 3 days in the treatment of relapsed or refractory acute leukemia or lymphoma. PATIENTS AND METHODS: Patients with leukemia or lymphoma were escalated in separate strata. Stratum I consisted of 11 patients, median age of 47 years (range, 18 to 68 years), with relapsed or refractory leukemia. Stratum II contained nine patients, median age of 48 years (range, 39 to 68 years), who had refractory non-Hodgkin’s lymphoma. Patients received irinotecan at 40 mg/m2 daily for 3 days, beginning just before the first dose of gemcitabine. Gemcitabine was given at 10 mg/m2/min, with the total duration adjusted following a modified continuous reassessment model. RESULTS: Severe myelosuppression and stomatitis/esophagitis were the most serious hematologic and nonhematologic toxicities. Several patients developed febrile neutropenia, nausea, or vomiting. In both strata, the max...
Modal Analysis of Gear Considering Temperature Based on ANSYS

In this paper, regarding a spur gear as the object, the natural characteristics under thermal effect are calculated by using ANSYS. Firstly, taking the friction heat and convection heat as the thermal loads, the gear is analyzed under a steady state temperature. Secondly, taking the thermal stress into account, the natural frequencies are calculated. Comparing the natural frequencies between change and without change of temperature. The result of this study shows that the thermal stress produced by the variation of temperature is the main reason of natural frequency change.
On the security of group communication schemes based on symmetric key cryptosystems

Many emerging applications in both wired and wireless networks, such as information dissemination and distributed collaboration in an adversarial environment, need support of secure group communications. There have been many such schemes in the setting of wired networks. These schemes can be directly adopted in, or appropriately adapted to, the setting of wireless networks such as mobile ad hoc networks (MANETs) and sensor networks. In this paper we show that the popular group communication schemes that we have examined are vulnerable to the following attack: an outsider adversary who compromises a legitimate group member could obtain some or all past group keys as well as the current group key; this is in sharp contrast to the widely-accepted belief that a such adversary can only obtain the current group key. This attack is very powerful also because it provides the adversary the following flexibility: since the adversary knows which members are the "most valuable" ones from its own perspective of view, compromise of any such member leads to the exposure of all the past and current group keys. This flexibility is particularly relevant in the setting of MANETs and sensor networks because they are typically deployed in a small area and the adversary can capture and compromise the easiest-to-obtain node. In order to deal with this powerful attack, we formalize two security models for stateful and stateless group communication schemes, respectively. We show that some practical methods can make a subclass of the group communication schemes immune to this attack at the following extra expense: at each rekeying event, a group member conducts logarithmically-many pseudorandom function evaluations.
A Hybrid Mimo Phased-Array Concept for Arbitrary Spatial Beampattern Synthesis

Multiple-input multiple-output (MIMO) radar is a multiple aperture technology characterized by the ability to transmit diverse signals at each aperture. This is in contrast to traditional phased-array radar whereby a single signal is transmitted with a phase shift applied at each element to enable steering of the transmit beam. The hybrid MIMO phased-array radar (HMPAR) concept is an outgrowth of the monostatic MIMO construct, in which all sensors have the same view of the far-field target. In the HMPAR, the full transmit array is partitioned into sub-arrays which can be electronically steered in different directions and driven by separate transmit waveforms; furthermore the configuration of the array into sub-arrays can be changed. Here we explore the variety of transmit beampatterns that could be achieved using such a system.
Mathematical models in decision analysis

Decision analysis offers powerful techniques to understand and evaluate uncertain clinical situations better. Decision analytic models are appearing with increasing frequency in health policy planning, clinical information and decision-support computer systems, evaluations of clinical pathways, development of clinical practice or utilization review guidelines, and epidemiologic research. This article describes the structure, application, and limitations of the more popular decision analytic methods, including decision trees, Markov models, Monte Carlo simulation, survival and hazard functions, fuzzy logic, and sensitivity analysis. Understanding the nature of these methods will help readers to assess better the appropriateness of their use in published reports.
Recurrent Pregnancy Loss in Women with Killer Cell Immunoglobulin-Like Receptor KIR2DS1 is Associated with an Increased HLA-C2 Allelic Frequency

Problem During human pregnancy, the uterine lining is highly populated with killer-immunoglobulin-like receptor (KIR)-expressing NK cells that recognize HLA-C molecules on trophoblast cells. The goal of this study was to analyze the KIR gene contents and frequencies in a N. American cohort of women with RPL of unknown etiology to evaluate whether there is a genetic susceptibility to RPL based on a woman's KIR repertoire and her HLA-C group, as well as the HLA-C group of the partner. Method of study The frequencies of KIR and HLA-C1 and HLA-C2 genes were evaluated in 139 Caucasian women with RPL; HLA-C1, and HLA-C2 group genes were analyzed in their partners (n = 42). The gene frequencies were compared with data reported from corresponding populations. Results Overall, the frequencies of HLA-C groups and KIR genes and genotypes in RPL cohort resembled the frequencies for US Caucasians. The HLA-C1 and HLA-C2 group distribution was significantly different between women with or without KIR2DS1. Women positive for KIR2DS1 (45.3% of the study cohort) had an increased frequency of its ligand, HLA-C2 (0.5159 versus 0.3684 in KIR2DS1 negative women, P = 0.014). Conclusion Our results indicate that among KIR2DS1 pos women, the co-expression of HLA-C2 is associated with RPL.
War and domestic political violence

This paper is concerned with the indirect systemic linkages whereby conflict at one level (in this case war involvement) generates systemic changes at the domestic level, which in turn alter the character of conflict at that level. To evaluate these linkages, I examine the changes in the magnitude and intensity of economic, social, and political violence in the domestic system that occur before, during, and after war involvement. Data have been collected on 2,861 violent events during this period. The impact of war on the pattern of these events is evaluated through the use of an interrupted time series, quasi-experimental design. The analysis indicates that war did have a significant, although different, impact on the pattern of domestic violence for each of the five wars.
Channel Interactions in a Vertically Differentiated Channel Structure: The Case of Factory Outlet Stores

This study develops and estimates a model of multi-channel customer purchase behavior in a vertically differentiated channel structure. In recent years many retailers have added exclusively sourced factory outlet stores into their channel mix to achieve market expansion and customer segmentation. However, there are two main concerns for retailers who offer a lower quality alternative channel under the same brand name: cannibalization and the impact of the adoption of the lower quality channel on total spending with the retailer. The current literature has two conflicting predictions regarding the impact of adoption of the outlet channel on total spending with the retailer. Multichannel customer behavior research suggests that customer interaction using more channels would be beneficial for the retailer and lead to increased spending. Brand extension research, on the other hand, suggests that adoption of the lower quality channel might run the risk of brand dilution and lead to decreased spending. Using an individual level customer transaction data set from a large specialty apparel retailer, we investigate the impact of adoption of the outlet channel. We jointly model customer purchase timing, channel choice and expenditure decisions. Our results show that on average, overall spending with the retailer increases after the adoption of the outlet channel due to increased purchase frequency. More surprisingly, in addition to incremental spending at the outlet channel, there is a positive spillover that results in increased spending at the retail store channel. Ours is the first empirical study investigating multichannel customer behavior in a vertically differentiated channel structure. Our results showcase the effectiveness of this channel structure in customer segmentation. We find that by offering the lower quality, lower price channel the retailer is able to significantly increase the purchase frequency and spending of the customers on the lower end of the pre-outlet adoption expenditure distribution with no cannibalization on the higher end.
Simultaneous Determination of Xylazine and Its Major Metabolite, 2,6-Dimethylaniline, in Bovine and Swine Kidney by Liquid Chromatography.

A liquid chromatographic (LC) method is described for the simultaneous determination of xylazine (XY) and its major metabolite, 2,6-dimethylaniline (2,6-DMA), in bovine and swine kidney in the 25-100 ppb range. XY and 2,6-DMA are extracted from kidney with chloroform, followed by cleanup on an acidic Celite 545 column. A mu Bondapak phenyl column is used for LC separation with UV determination at 225 nm. The mobile phase is a mixture of acetonitrile, water, sodium acetate, and acetic acid. Mean recoveries from bovine kidney were 78.3% for XY, with a standard deviation (SD) of 7.45 and a coefficient of variation (CV) of 9.51%, and 87.2% for 2,6-DMA, with an SD of 8.38 and a CV of 9.61%. Mean recoveries from swine kidney were 80.8% for XY, with an SD of 5.92 and a CV of 7.33%, and 86.7% for 2,6-DMA, with an SD of 6.16 and a CV of 7.10%.
Relational goods and overcoming barriers to collective action

Relational goods contribute to understanding why people engage in collective action, notably including political participation, even though, as Olson showed, it would often be more rational for them to free-ride on the activity of others. Relational goods are neither public goods nor private goods but a third type of good. They must be jointly consumed with another person or persons (unlike private goods), but the identity of the other persons matters crucially (unlike the case for public goods). Relational goods can only exist by mutual agreement as part of a relationship with non-arbitrary others, in the context of an interaction. Friendship is a prototypical example. Relational goods can exist along a range of personal contact from direct, where individuals interact face to face, to indirect, where the interaction may be at a distance with a certain type of person. In the indirect case the relational good may frequently take the form of reinforcing a desired social identity. The distinction between “consumption” and “instrumental” goods applies, parallel with other usage. The consumption relational goods are produced independent of any consequences of the action or relationship, while the instrumental ones refl ect consequences, such as from an action that enhances the value of an identity. People who value relational goods may act collectively even if other net benefi ts of action are negative. Larger groups become more, not less, prone to collective activity. Relational goods provide a missing element to understand how the process of mobilization works at the individual level; leaders can infl uence people’s perceptions of what others are doing, of the value of a shared identity, and of the likelihood of success. Some limited empirical evidence is consistent with relational goods playing a role in enhancing collective action.
A Test of Leading Explanations for the College Racial-Ethnic Achievement Gap: Evidence from a Longitudinal Case Study

In this study, we examined racial/ethnic differences in grade point average (GPA) among students at a highly selective, private university who were surveyed before matriculation and during the first, second and fourth college years, and assessed prominent explanations for the Black-White and Latino-White college achievement gap. We found that roughly half of the observed gap was attributable to family background characteristics and pre-college academic preparation. Of the within-college factors we considered, perceptions of campus climate and selection of major field of study were most important in explaining racial/ethnic differences in GPA. Personal resources, such as academic effort, self-esteem and academic identification, and patterns of involvement in campus life were significantly associated with GPA, but these factors did not account for racial/ethnic differences in academic performance. Overall, our results suggest that efforts to reduce the college achievement gap should focus on assisting students with the process of selecting major fields of study and on fostering a welcoming and inclusive campus environment.
Identification of Zeta (S) Opioid Receptor Binding Polypeptides in Rat Cerebellum

Growth factors are known to be crucial in dictating the course of cellular proliferation and differentiation1-4. Developing cells and tissues may be subjected to a host of elements that can stimulate or inhibit growth processes, ultimately serving to determine the number and type(s) of cells composing the mature organ. Nervous system development is a carefully orchestrated process that consists of a cascade of events (i.e., cell proliferation, migration, differentiation) which legd to the harmonious functioning unit vital to the organism5. One such event that is critical to achieving a successfully working nervous system is determination of the number of neuronal and glial cells. In humans, literally billions of cells are replicated and differentiated in a very short time, with most of the process of cellular replication occurring during prenatal life and in the early postnatal period. Indeed, by 18 months of age, the human nervous system has largely formed the neurons and many of the glia constituting the adult. Two forces are integral to determining the proper cell number. Cells must be allowed or even stimulated to proliferate, and repressed when the approporiate number has been achieved. Needless to say, if this process of cell replication malfunctions, short-and long-term damage may occur. Thus, dysfunction of these processes could lead to abnormally fewer cells which would compromise neural integration and signalling, or it could result in too many cells that may lead to neural neoplasia. While a number of growth factors are known to excite and stimulate cell proliferation, our knowledge of factors that curtail cell proliferation is extremely limited.
Geometric Patterns for Neighboring Bases Near the Stacked State in Nucleic Acid Strands.

Structural variation in base stacking has been analyzed frequently in isolated double helical contexts for nucleic acids, but not as often in nonhelical geometries or in complex biomolecular environments. In this study, conformations of two neighboring bases near their stacked state in any environment are comprehensively characterized for single-strand dinucleotide (SSD) nucleic acid crystal structure conformations. An ensemble clustering method is used to identify a reduced set of representative stacking geometries based on pairwise distances between select atoms in consecutive bases, with multiple separable conformational clusters obtained for categories divided by nucleic acid type (DNA/RNA), SSD sequence, stacking face orientation, and the presence or absence of a protein environment. For both DNA and RNA, SSD conformations are observed that are either close to the A-form, or close to the B-form, or intermediate between the two forms, or further away from either form, illustrating the local structural...
Effect of Swelling on Multiple Energy Transfer in Conjugated Polymer Nanoparticles

Many key processes in conjugated polymers are strongly influenced by multiple energy transfer (i.e., exciton diffusion). We investigated the effect of solvent-induced swelling on the kinetics of multiple energy transfer in nanoparticles of the conjugated polymers PFBT and MEH-PPV. Multiple energy transfer between equivalent chromophores results in an increased rate of quenching by defects due to a cascading or funneling effect. The effects of swelling on energy transfer between polymer chromophores and the resulting exciton dynamics were modeled using a random walk on a lattice of chromophores. The simulation results show good agreement with experimental fluorescence quantum yield, and decay kinetics results at low to moderate THF concentrations. We found that the time scale for energy transfer between chromophores (∼5 ps for MEH-PPV nanoparticles and ∼100 ps for PFBT nanoparticles) is highly sensitive to swelling, slowing by an order of magnitude or more for swelled particles. The results support quenchi...
Personalized cancer therapy for patients with metastatic medullary thyroid cancer (MTC).

TPS6101 Background: Standard approaches in cancer research identify new therapies based on observed benefit to average populations, but without emphasis on individual patients whose responses can v...
Fast Protein Translation Can Promote Co- and Posttranslational Folding of Misfolding-Prone Proteins

Chemical kinetic modeling has previously been used to predict that fast-translating codons can enhance cotranslational protein folding by helping to avoid misfolded intermediates. Consistent with this prediction, protein aggregation in yeast and worms was observed to increase when translation was globally slowed down, possibly due to increased cotranslational misfolding. Observation of similar behavior in molecular simulations would confirm predictions from the simpler chemical kinetic model and provide a molecular perspective on cotranslational folding, misfolding, and the impact of translation speed on these processes. All-atom simulations cannot reach the timescales relevant to protein synthesis, and most conventional structure-based coarse-grained models do not allow for nonnative structure formation. Here, we introduce a protocol to incorporate misfolding using the functional forms of publicly available force fields. With this model we create two artificial proteins that are capable of undergoing structural transitions between a native and a misfolded conformation and simulate their synthesis by the ribosome. Consistent with the chemical kinetic predictions, we find that rapid synthesis of misfolding-prone nascent-chain segments increases the fraction of folded proteins by kinetically partitioning more molecules through on-pathway intermediates, decreasing the likelihood of sampling misfolded conformations. Novel to this study, to our knowledge, we observe that differences in protein dynamics, arising from different translation-elongation schedules, can persist long after the nascent protein has been released from the ribosome, and that a sufficient level of energetic frustration is needed for fast-translating codons to be beneficial for folding. These results provide further evidence that fast-translating codons can be as biologically important as pause sites in coordinating cotranslational folding.