cssi/SciSciGPT-SciSciNet huggingface dataset:
A parametric study of thermally augmented O2/H2 rocket enines

An analysis is presented of the performance of a conceptual propulsion system in which liquid hydrogen and liquid oxygen are first vaporized and heated by thermal power from a spacecraft nuclear electric power supply prior to combustion in a rocket engine. Calculations of the specific impulse (I-sp) are presented for a series of O2/H2 oxidizer-to-fuel mixture ratios and reactant pre-heat temperatures (T-aug). It is found that the ratio of the augmentation power to the total engine jet power (P-aug/P-tot) determines the engine thrust for a given P-aug, T-aug, and I-sp. In addition, the performance of an unaugmented O2/H2 and a heated-hydrogen rocket engine were also calculated for the same conditions. Results show that an augmented O2/H2 engine has three to eight times the thrust of a heated H2 engine for a given P-aug. It is concluded that it should be possible to design a high/low thrust propulsion system using a common propellant, with the option of using thermal power from the nuclear electric power supply to augment the low-thrust propulsion system during cruise periods when the reactor's full electric power is not needed.
In Defense of Gibbs and the Traditional Definition of the Entropy of Distinguishable Particles

The traditional Gibbs’ calculation of the entropy of distinguishable classical particles that leads to Gibbs Paradox has been criticized recently. This criticism, if valid, would require a substantially different definition of entropy in general. However, the traditional definition of entropy works quite well in situations where the distinguishability of classical particles is taken seriously while a suggested replacement definition fails.
Evidence of recent changes in global snow and ice cover

Data on recent variations in the seasonal extent of snow cover and sea ice, of the terminal position and volume of alpine glaciers, and of ground temperature profiles in permafrost areas are reviewed. The extent of seasonal snow cover and of sea ice has fluctuated irregularly over the last 15–20 years. There is no apparent response to global warming trends. In contrast, most glaciers retreated and thinned from the late 19th century until the 1960s and Alaskan permafrost temperatures have risen 2°–4° C per century. Recently, some glacier advances have been noted.
Can psychiatry contribute to international conciliation

Abstract Most psychiatrists, like other human beings, say they desire peace, and yet like other human beings they mean different and incompatible things by it. Some recommend the acceptance and understanding of reality (i.e., power); others consider the primacy of ethics over politics and identify their wish for harmony of interests between nations with the existence of some harmony. As citizens, they can and should express these opinions. As professionals, some of them can make only a small but vital contribution towards international conciliation by focusing on the concomitant need for realism and idealism. Psychiatry can attempt to make palatable the idea that problems of political change, whether national or international, must be based on a compromise between morality and power. Oscillations between apparently opposite poles of force, and appeasement in foreign policy should be acceptable to a profession who is faced with the intimate oscillations of human beings. Psychiatrists are uniquely qualified to accept that two opposite things can be equally true. In the area of world affairs psychiatrists need to combine their observations and analysis with a good grasp of the existing reality. In this work, like in their work with patients, they need to be aware of their own personal standards and how those are rooted in the existing reality. An analyst of world affairs, however, needs to know not only his own but also the values of the international actor. Such an analyst needs to understand the identity of leadership, how this leadership is affected by internal and external change, and the causal interdependence of internal and external behavior. “What is acceptable or essential for a society are phenomenon to be measured not values to be asserted.” 1
Sixty-four–slice multidetector computed tomography: the future of ED cardiac care

Multidetector computed tomography (MDCT) imaging, a technological advance over traditional CT, is a promising possible alternative to cardiac catheterization for evaluating patients with chest pain in the emergency department (ED). In comparison with traditional CT, MDCT offers increased spatial and temporal resolution that allows reliable visualization of the coronary arteries. In addition, a "triple scan," which includes evaluation for pulmonary embolism and thoracic aortic dissection, can be incorporated into a single study. This test will enable emergency physicians to rapidly evaluate patients for life-threatening illnesses and may allow safer and earlier discharges of many patients with chest pain in comparison with a traditional rule-out protocol. In this article, we will highlight the technological advances of MDCT imaging, review the literature on coronary angiography via MDCT, and discuss the future of this technology as it relates to the ED.
The general structure of composite propagators from the renormalization group and analyticity

Abstract A representation incorporating the constraints of renormalizability and analyticity is derived for propagators of composite particles. We elaborate on how asymptotic freedom and the associated normalization of a propagator and its absorptive part respect analyticity. This is accomplished quite differently for a composite field than for an elementary one, such as the quark or gluon. As a by-product we show that the small coupling and small momentum limits cannot generally be interchanged and that, consequently, there are circumstances whent the free field limit cannot be obtained as a small coupling limit of the fully interacting result. We also show how the classic Landau singularity can be avoided by requiring these general constraints to be valid.
Addressing the STEM Teacher Shortage in American Schools: Ways to Recruit and Retain Effective STEM Teachers

The shortage of certified science, technology, engineering, and mathematics (STEM) teachers is of concern throughout the United States because of significant numbers needed over the next over the next 10 years. Addressing this issue in education, this study examined the experiences of three new STEM teachers who entered teaching through different pathways, focusing on those experiences related to the effectiveness of mentoring and the meaningfulness of professional development. Based on three case-study analysis, the findings provide an insight into the importance of mentoring and professional development for STEM teachers during their induction year to promote teacher persistence in the profession. This article provides ideas for recruitment, instructional preparation, and STEM teacher retention practices.
Soft Tissue Tumors of the Hand. 1. Benign

Soft tissue tumors of the hand arise from skin, subcutaneous tissue, tendons, nerve, and blood vessels. Many of these lesions occur on other parts of the body; however, the hand remains a unique site because these tumors have symptoms, appearances, treatments, and prognoses that may be quite different than when on other parts of the body. Their characteristics and the severity of symptoms vary markedly depending on the exact location, size, and type of tumor-and many of these tumors can have multiple forms of presentation. Two articles are intended to provide an overview of benign (this article) and malignant tumors (subsequent issue) of the hand. The rarer and more deleterious tumors are discussed in detail while the common tumors and epidermal lesions with which practitioners are familiar are briefly overviewed. At the completion of these review articles, participants should be able to identify and diagnose various benign and malignant hand tumors as well as understand the accepted current treatment of these growths.
Characterization of some proteins associated with viruses in the potato Y group

Abstract Cytoplasmic inclusions induced by tobacco etch virus (TEV), potato virus Y (PVY), pepper mottle virus (PMV), bidens mottle virus (BiMV), and turnip mosaic virus (TuMV) as well as the respective viruses were purified from infected tissue and their constituent proteins investigated. A procedure is described for the simultaneous purification of virus and its associated inclusions. Electron microscopy of the purified inclusion preparations revealed structures characteristic of those seen in situ for each virus and are described as laminated aggregates shaped as triangles for TEV and as rectangles for BiMV, as scrolls for PVY and PMV, and as scrolls and laminated aggregates shaped as triangles for TuMV. Polyacrylamide electrophoresis of the cytoplasmic inclusions in 0.1% sodium dodecyl sulfate (SDS) revealed one protein component with an estimated molecular weight of 67,000 for PVY; 67,400 for PMV; 69,300 for BiMV; 69,600 for TEV; and 70,300 for TuMV. SDS electrophoresis of the viral coat proteins revealed anomalies, dependent in part on the history of the purified virus. Molecular weights of viral coat protein were estimated to be 26,000 and 32,000 for TEV; 28,000 and 34,000 for PVY; 28,000 and 34,000 for PMV; 28,000 and 33,000 for BiMV; and 27,000 and 36,000 for TuMV. Electrophoresis using different acrylamide gel concentrations and cellulose acetate support medium suggested that the larger of the two molecular weights estimated for each viral coat protein was a charge isomer.
Effects of iodized feed on stress modulation in steelhead trout, Oncorhynchus mykiss (Walbaum)

In the aquaculture industry, the physiological systems of fish can be chronically stressed by various biological, chemical and physical factors. Chronic stress leads to a decrease in the overall health and growth of the fish, making them more prone to diseases. Dietary iodine has been shown to reduce this stress response in chickens and increase disease resistance in dairy cattle, but the mechanisms by which iodine affects stress resistance and immunocompetency is not completely understood and has not been extensively studied in fish. This study investigated the effects of iodized feed as a nutritional supplement in relation to stress modulation in steelhead trout (Oncorhynchus mykiss). We investigated effects on primary, secondary and tertiary stress responses by measuring plasma levels of cortisol, glucose and thyroid hormones as well as haematocrit percentage and average growth rate in steelhead trout. Iodine-supplemented fish, on average, had lower levels of plasma cortisol and glucose and lower packed cell volumes than fish fed with regular commercial feed (P<0.05). Iodine-supplemented fish also showed higher levels of thyroid hormones and exhibited better growth over the period of the experiment (P<0.05). It was concluded that, used with other husbandry practices, use of iodine-supplemented feed could lead to better host defence, growth and survival in fish raised in the aquaculture industry.
An Electron Microscope Study of Chorioallantoic Membrane Infected with the Virus of Avian Infectious Bronchitis

herpes simplex and vaccinia: A study with thin sections for the electron microscope. Bull. Johns Hopkins Hosp. 87: 511-547. 5. Eddy, B. E. and Wyckoff, R. W. G. 1950, Influenza virus in sectioned tissues. Proc. Soc. Exper. Biol. 8c Med. 75: 290-293. 6. Wyckoff, R. W. G. 1951, Electron microscopy of chick embryo membrane infected with PR-8 'influenza. Nature, 168: 651-653. 7. Murphy, J. S. and Bang, F. B. 1952, Observations with the electron microscope on cells of the chick chorio-allantoic membrane infected with influenza virus. J. Exper. Med. 95: 259268. 8. Wyckoff, R. W. G. 1953, Formation of the particles of influenza virus. J. Immunol. 70: 187-196. 9. Morgan, C, Rose, H. M. and Moore, D. H. 1955, Structure and development of influenza virus in cells of chick chorioallantoic membranes examined in ultrathin sections. Proc. 13th Ann. Meeting Electron Microscope Society of America. 1955: 9. and rabies17 have been studied in situ in infected tissue with the aid of the electron microscope. These studies have revealed information pertaining not only to virus morphology and reproduction, but also to chorioallantoic and other tissue morphology and pathology. To add to the present information it appeared desirable to study a virus-host complex that had not as yet been studied in tissue by electron microscopy.
Modeling Tetracycline Antibiotic Sorption to Clays

Sorption interactions of three high-use tetracycline antibiotics (oxytetracycline, chlortetracycline, tetracycline) with montmorillonite and kaolinite clays were investigated undervaried pH and ionic strength conditions. Sorption edges were best described with a model that included cation exchange plus surface complexation of zwitterion forms of these compounds. Zwitterion sorption was accompanied by proton uptake, was more favorable on acidic clay, and was relatively insensitive to ionic strength effects. Calcium salts promoted oxytetracycline sorption at alkaline pHs likely by a surface-bridging mechanism. Substituent effects among the compounds in the tetracycline class had only minor effects on sorption edges and isotherms under the same solution pH and ionic strength conditions. At low ionic strength, greater sorption to montmorillonite than kaolinite was observed at all pHs tested, even after normalizing for cation exchange capacity. These results indicate that soil and sediment sorption models for tetracyclines, and other pharmaceuticals with similar chemistry, must account for solution speciation and the presence of other competitor ions in soil or sediment pore waters.
Thermal stability of nanostructured Al93Fe3Cr2Ti2 alloys prepared via mechanical alloying

Abstract Thermal stability of nanostructured Al 93 Fe 3 Ti 2 Cr 2 alloys prepared via mechanical alloying (MA) starting from elemental powders was investigated using a variety of analytical techniques including modulated differential scanning calorimetry, X-ray diffraction, scanning electron microscopy, transmission electron microscopy coupled with energy dispersive spectrometry and microdiffraction. The results showed that the MA-processed Al 93 Fe 3 Ti 2 Cr 2 alloy in the as-milled condition was composed of an Al-based supersaturated solid solution with high internal strains. Release of internal strains, intermetallic precipitation and grain growth occurred upon heating of the MA-processed Al alloy. Nevertheless, grain growth in the MA-processed Al alloy was very limited and fcc-Al grains with sizes in the range of 20 nm were still present in the alloys after exposure to 450 °C (0.77 T m ).
Yohimbine induces sympathetically mediated renin release in the conscious rat.

Abstract The preferential α2-adrenergic antagonist yohimbine (4 mg/kg s.c) caused a time-related increase in serum renin activity and heart rate in conscious Sprague-Dawley rats. Although mean arterial pressure was not decreased significantly over the 2-h period, heart rate was elevated significantly at 15 and 30 min post-injection. In contrast, serum renin activity remained elevated for up to 2 h with a 9-fold and 9.7-fold increase occuring at 30 and 60 min post-injection, respectively. Yohimbine (0.3, 1, 3 and 10 mg/kg s.c.) elicited a dose-related increase in serum renin activity and heart rate (30 min post-injection). The 1 mg/kg dose of yohimbine did not alter blood pressure whereas the 3 mg/kg dose caused a variable decrease in mean arterial pressure. The highest dose of yohimbine (10 mg/kg) significantly lowered blood pressure. The β-adrenergic receptor antagonist propranolol (1.5 mg/kg s.c.), blocked the renin release and tachycardia caused by yohimbine (1 and 3 mg/kg s.c.), and the ganglionic blocking agent chlorisondamine partially inhibited the renin release elicited by 3 mg/kg (s.c.) of yohimbine. The prostaglandin synthetase inhibitors indomethacin (5 mg/kg s.c.) and meclofenamate (5 mg/kg s.c.) impaired the ability of yohimbine (3 mg/kg) to elevate SRA but did not alter the hemodynamic effects of yohimbine. Thus, the increase in renin release caused by yohimbine appears to be mediated by the sympathetic nervous system. Because the smaller doses of yohimbine increase renin release in the absence of a decrease in mean arterial pressure, it is unlikely that yohimbine stimulates renin release by baroreflex-mediated activation of the renal sympathetic nerves. We feel that yohimbine increases the rate of release of norepinephrine onto the granular juxtaglomerular cells of the kidney by blocking prejunctional α2-adrenergic receptors on the renal sympathetic nerve and/or a centrally mediated activation of the peripheral sympathetic nervous system.
Cholera toxin-A subunit blocks opioid excitatory effects of sensory neuron action potentials indicating mediation by Gs-linked opioid receptors

Our previous studies indicated that opioid-induced prolongation of the Ca2+ component of the action potential duration (APD) in dorsal root ganglion (DRG) neurons is mediated by excitatory opioid receptors that are coupled to cyclic AMP-dependent voltage-sensitive ionic conductances. In the present study, DRG neurons were treated with cholera toxin (CTX), or with the A subunit of CTX, in order to determine if these excitatory opioid receptors are positively coupled via the GTP-binding protein Gs to the adenylate cyclase/cyclic AMP system. In contrast, inhibitory opioid receptors have been shown to be linked to pertussis toxin-sensitive Gi/Go regulatory proteins that mediate APD shortening responses. After pretreatment of DRG-spinal cord explants with remarkably low concentrations of CTX-A (1pg/ml-1ng/ml; > 15min) or whole toxin (1 pg/ml-1 μg/ml) the APD prolongation elicited in DRG neurons by 1–10 nM δ/μ (DADLE) or κ (U-50, 488H) opioids was blocked (29 out of 30 cells), whereas APD shortening by μM opioid concentrations was unaffected. Opioid-induced APD prolongation was blocked even when the initial treatment with CTX or CTX-A alone did not prolong the APD. The blocking effects of CTX and CTX-A were reversed in tests made 2 h after return to control medium. The mechanisms underlying the unusually potent blocking effects of CTX and CTX-A on opioid excitatory modulation of the APD of DRG neurons require correlative biochemical analyses. Nevertheless, the results of the present study provide strong evidence that opioid-induced APD prolongation in DRG neurons is mediated by excitatory opioid receptors that are coupled to a CTX-sensitive, Gs-like regulatory protein. Together with our previous studies, these results suggest that excitatory opioid receptors on DRG neurons are positively coupled via Gs to the adenylate cyclase/cyclic AMP second messenger system (resembling, for example, s-noradrenergic receptor functions), in contrast to inhibitory opioid receptor linkage to Gi/Go (resembling α2-noradrenergic receptors).
Involvement of neutrophils in the pathogenesis of lethal myocardial reperfusion injury

Neutrophils respond to myocardial ischemia-reperfusion in a manner similar to the bacterial invasion of a host. The inflammatory-like response that follows the onset of reperfusion involves intense interactions with the coronary vascular endothelium, arterial wall, and cardiomyocytes in a very well-choreographed manner. Neutrophils have been implicated as primary and secondary mediators of lethal injury after reperfusion to coronary vascular endothelium and cardiomyocytes. The involvement of neutrophils in the pathogenesis of lethal myocardial injury has been inferred from (1) their presence and accumulation in reperfused myocardium in temporal agreement with injury induced, (2) the armamentarium of toxic agents such as oxidants and proteases that are released by neutrophils in reperfused myocardium, (3) responsivity to (recruitment by and/or activation by) inflammatory factors released by reperfused myocardium, and (4) inhibition of lethal post-ischemic myocyte or endothelial cell injury by strategies that interdict neutrophil interactions at any number of stages. However, whether neutrophils are directly involved in the pathogenesis of lethal reperfusion injury in the myocardium, are just pedestrian (first) responders to inflammatory signals released after the onset of reperfusion, or are important to an early but not clinically important phase of pathology are still points of controversy. As with the general area of myocardial protection itself, the failure to reproduce the salubrious effects of anti-neutrophil therapeutic strategies and to successfully translate these strategies into clinical practice has not only fueled the debate, but has jeopardized the further pursuit of myocardial protection therapeutics to improve post-ischemic outcomes. This review will describe the molecular responses of neutrophils to ischemia-reperfusion, discuss the cellular and tissue damage inflicted either directly or indirectly by these white cells, and discuss the physiological impact of interdiction of neutrophil-mediated interactions with myocardial cells at various levels on lethal post-ischemic injury. In addition, it will discuss the arguments for and against the involvement of neutrophils in responses to ischemia-reperfusion in experimental models, and the failure to translate experimentally successful therapy into clinical practice.
Transfer lengths and spin injection from a three-dimensional ferromagnet into graphene

In graphene spintronic devices, spin currents are injected and probed by three-dimensional ferromagnetic electrodes on a two-dimensional graphene layer. Here we develop a unified theory to understand the observed spin-injection signals and their dependence on a dc-bias current in these devices by different groups. The spin-dependent transfer length, which measures the length required for a current to change from lateral in graphene to vertical in the electrode, is found to play a central role in determining the spin-current distribution as well as the signal fidelity. The theory consistently explains the experiments and suggests that the observed dc-bias dependence is due not to change in the spin-injection efficiency but to redistribution of the spin current near the ferromagnetic electrode.
What is the annual net flow of undocumented mexican immigrants to the united states

Senior government officials have claimed that in recent years an average of 1.4 million illegal aliens have entered the United States annually without apprehension. This conjectural figure does not take into account the fact that the net flow of immigrants is always less than the gross flow. In this paper, seven estimates are made concerning the net flow of undocumented Mexican immigrants to the United States in the period 1970–1975. These estimates are based on the growth of the population of Mexican origin according to the Current Population Survey. According to these estimates the annual net flow ranged from 82,300 to 232,400 persons.
Note on Frobenius extensions and restricted Lie superalgebras

Abstract This article extends techniques concerning Frobenius extensions in order to study enveloping algebras of restricted Lie superalgebras. In particular, we determine those restricted Lie superalgebras whose enveloping algebras are of finite representation type. In contrast to the non-graded case these algebras are not necessarily serial.
Polymer-bound phosphine-substituted tetrairidium carbonyl clusters: Catalysts for olefin hydrogenation

Abstract Unique tetrairidium carbonyl clusters were anchored to phosphine-functionalized poly(styrenedivinylbenzene), the metal species being identified by carbonyl infrared spectra as the clusters analogous to [Ir4(CO)21 − x(PPh3)x] (x = 1, 2, or 3). Infrared spectra of polymer membranes functioning as catalysts for ethylene and cyclohexene hydrogenation in a flow reactor at 1 atm and 40–80 °C indicated that the predominant metal species in each catalyst was the originally prepared tetrairidium cluster. The catalysts were stable, exhibiting unchanged spectra and undiminished activity for as many as 5000 turnovers at temperature 120 °C, the iridium clusters aggregated to form crystallites. Catalytic kinetics measured at
Marketing Latinos as Development Policy: San Antonio and the Reproduction of Underprivilege

The marketing of cultural identity has been increasingly forwarded as a strategy to improve the social and material circumstances of minority groups who have traditionally been excluded from full political and economic participation in society. But what this article will illuminate in San Antonio, Texas – the largest city in the United States with a municipal economy resting on this strategy – is the emergence of an urban multicultural landscape that is culturally inclusive but materially exclusive – thus producing a celebration of cultural diversity that maintains the existing disparities in material wealth. This process is but a mere fraction of the greater commodification of culture occurring globally. The contention that minority development can be achieved through the marketing of cultural identity is disproved.
Effects of non-uniform inhibitor production on the growth of cancer cell cultures

Abstract A diffusion model to examine the effects of non-uniform inhibitor production on the growth of a cancer cell culture is presented. This inhibitor is assumed to be a product of the metabolic processes of living cells in the cell culture.
A new DNA marker, U15557, is linked to protease inhibitor and adenylate kinase-1 in the laboratory opossum, Monodelphis domestica.

Summary A 323-bp DNA fragment (U15557) was isolated, cloned, and sequenced after polymerase chain reaction (PCR) amplification from Monodelphis domestica genomic DNA. AHindIII restriction fragment length polymorphism was identified in this species using the U15557 PCR. fragment as a hybridization probe. DNA samples exhibited either a 6.4kb band, a 7.2 kb band, or both bands simultaneously. Behaviour of these two variants in family studies was consistent with codominant autosomal inheritance. Linkage between this marker and the loci encoding protease inhibitor (PI) and adenylate kinase 1 (AK1) was found in M. domestica.
If All You Have Is A Hammer Finding Economic Development Policies That Matter

This research explores the relative effectiveness of a comprehensive set of local economic development incentives and focuses on two questions: What contributions do common development tools make to the economic health of municipalities?; and, Are there other types of local activities, not typically considered as development tools, that might be more effective in contributing to local economic prosperity? It finds that the factors most consistently and positively related to economic health are investments in the downtown, spending on basic local public services, and using no economic development incentives at all. These findings suggest one primary policy recommendation: the wisest course of action for most cities would be to eschew particularized development incentives, especially those that require tax expenditures.
Accelerating the Computation of Detailed Chemical Reaction Kinetics for Simulating Combustion of Complex Fuels

Combustion of hydrocarbon fuels has been a very challenging scientific and engineering problem due to the complexity of turbulent flows and hydrocarbon reaction kinetics. There is an urgent need to develop an efficient modeling capability to accurately predict the combustion of complex fuels. Detailed chemical kinetic models for the surrogates of fuels such as gasoline, diesel and JP-8 consist of thousands of chemical species and Arrhenius reaction steps. Oxygenated fuels such as bio-fuels and heavier hydrocarbons, such as from newer fossil fuel sources, are expected to have a much more complex chemistry requiring increasingly larger chemical kinetic models. Such models are beyond current computational capability, except for homogeneous or partially stirred reactor type calculations. The advent of highly parallel multi-core processors and graphical processing units (GPUs) promises a steep increase in computational performance in the coming years. This paper will present a software framework that translates the detailed chemical kinetic models to high-performance code targeted for GPU accelerators.
A latent class model for defining severe hemorrhage: Experience from the PROMMTT study

Background Several predictive models have been developed to identify trauma patients who have had severe hemorrhage (SH) and may need a massive transfusion protocol (MTP). However, almost all these models define SH as the transfusion of ≥10 units of red blood cells (RBCs) within 24 hours of ED admission (aka massive transfusion, MT). This definition excludes some patients with SH, especially those who die before a 10th unit of RBCs could be transfused, which calls the validity of these prediction models into question. We show how a latent class model could improve the accuracy of identifying the SH patients.
LV segmentation and mechanics in HCM: twisting the Rubik's Cube into perfection!

“…Sky knows the reasons and the patterns behind all clouds, and you will know, too, when you lift yourself high enough to see beyond…”—Richard Bach ([1][1]) Two-dimensional echocardiography, nuclear cardiology, and cardiac magnetic resonance have previously developed arbitrary schemes of
Selecting a composite correlation filter design: a survey and comparative study

Many composite correlation filter designs have been proposed for solving a wide variety of target detection and pattern recognition problems. Due to the large number of available designs, however, it is often unclear how to select the best design for a particular application. We present a theoretical survey and an empirical comparison of several popular composite correlation filter designs. Using a database of rotational target imagery, we show that some such filter designs appear to be better choices than others under computational and performance constraints. We compare filter performance in terms of noise tolerance, computational load, generalization ability, and distortion in order to provide a multifaceted examination of the characteristics of various filter designs.
Applications of vector geometry for robustness and speed

Implementing and using computer graphics and modeling systems rely on mathematical operations on points and vectors. This article shows how to use those concepts to derive and implement common graphics and modeling operations that maximize speed and numerical reliability. Vector geometric techniques represent and manipulate intrinsic relationships between objects, independent of coordinate systems. Their applications and the resulting computer code demonstrate their usefulness.
Characterization of neuraminidase activity of cultured human fibroblasts.

Abstract Investigations have been carried out to establish the enzymatic properties and specifications of the neuraminidase of cultured human fibroblasts. Homogenates of these cells cleaved the actylated derivative of neuraminic acid from fetuin, N- acetylneuraminyllactose and 2-(3′ methoxyphenyl) -N- acetyl-α-neuraminic acid. Maximum activity occurred between pH 4.2 and 4.6 in sodium acetate buffer. The K m values were 3.6 · 10−4 M, 3.0 · 10−3 M and 1.1 · 10−3 M, respectively, against fetuin, N- acetylneuraminyllactose and 2-(3′ methoxyphenyl) -N- acetyl-α-neuraminic acid. Against the first two substrates, the rate of hydrolysis fell below the expected value as the cell homogenate was diluted with water or 10 mN NaCl. Dilution with 8 mg/ml bovine serum albumin prevented the deviation and yielded the expected linear decrease. After the first 2-h incubation, the rate of hydrolysis decreased from the initial linear rate. The enzyme(s) was partially or completely inactivated by sonication at 20 kHz, freeze-thaw treatment, incubation at 52°C or storage for 48 h at −70°C. Suspension of the fibroblasts in water for 10 min at room temperature, followed by homogenization with a tissue grinder, yielded preparations that were suitable for the assay of the neuraminidase activity.
The glutathione synthesis inhibitor buthionine sulfoximine synergistically enhanced melphalan activity against preclinical models of multiple myeloma

Melphalan (L-PAM) has been an integral part of multiple myeloma (MM) treatment as a conditioning regimen before stem cell transplant (SCT). After initial response, most treated patients experience relapse with an aggressive phenotype. Increased glutathione (GSH) in MM may mediate resistance to L-PAM. We demonstrated that the GSH synthesis inhibitor buthionine sulfoximine (BSO) synergistically enhanced L-PAM activity (inducing 2-4 logs of cell kill) against nine MM cell lines (also in the presence of marrow stroma or cytokines) and in seven primary MM samples (combination indices 100 days, and significantly increased the median event-free survival relative to L-PAM alone. Combining BSO with L-PAM warrants clinical testing in advanced MM.
Physical activity and mammographic breast density: a systematic review

Studies show a protective relationship between physical activity and breast cancer risk across the life course from menarche to postmenopausal years. Mammographic breast density is a known and strong breast cancer risk factor. Whether the association of physical activity with breast cancer risk is mediated through mammographic breast density is poorly understood. This systematic review summarizes published studies that investigated the association between physical activity and mammographic breast density and discusses the methodological issues that need to be addressed. We included in this review studies that were published before October 31, 2011 that were accessible in full-text format and were published in English. We identified 20 studies through the PubMed Central, BioMed Central, Embase, and Scopus and using the search terms “physical activity and breast density” and “exercise and breast density” as well as through manual searches of the bibliographies of the articles identified in electronic searches. We found no evidence of association between physical activity and breast density across the studies by grouping them first by the timing of physical activity assessment (in adolescence, current/recent, past, and lifetime) and then by women’s menopausal status (premenopausal and postmenopausal). Given the strength of the relationship between physical activity and breast cancer and the null findings of this review, it is unlikely that the effect of physical activity is mediated through an effect on breast density.
Growth Hormone Axis and Aging

Growth hormone (GH) and/or ghrelin mimetics represent potential treatment and/or prevention options for musculoskeletal impairment associated with aging. Use of improvement in muscle function as an outcome in studies of GH and ghrelin mimetics is complicated by the lack of a standardized definition for clinically meaningful efficacy of this end point. Based on preliminary study results, the use of ghrelin mimetics may be more suitable for use in this age group than GH itself. There are still several unanswered questions related to the use of ghrelin mimetics in the elderly, which prevents recommendation for its use at the current time.
On columnar arrangement of nerve cells in cerebral cortex

Abstract A columnar arrangement of cortical cells is more evident in man and other higher primates than it is in most non-primates. Columns can be readily seen in cortical regions of the cat, for example, but in lissencephalic specimen such as the rat columnar arrangement of cells is rarely demonstrable8. The mere fact that columns cannot clearly be made out in small brains implies that columns might not be of as fundamental importance as recent neurophysiological studies have suggested. The things are fairly clear: (1) The columns in man are certainly close enough so that one column may very well influence the next one. Whether this influence is inhibitory or excitatory, is impossible to say at the present time. We incline to think of an inhibitory fringe, as Powell and Mountcastle18 and others have found. Hubel's and Wiesel's7 work also suggests an inhibitory fringe, otherwise it is hard to account for the sharp boundary of excitatory fields which they observed. (2) The columns are not as clear-cut as expected, so that again, the relationships between them suggest that simultaneous interaction or cross-talk between the columns is quite likely to occur. We can therefore say that the columnar arrangement in the cortex may be more functionally real than anatomically apparent.
Novel cellular approaches to repair of neurodegenerative disease: from Sertoli cells to umbilical cord blood stem cells.

Neural transplantation is a promising approach to the treatment of neurodegenerative diseases and brain injury that has been shown to be efficacious in many animal models. However, the use of fetal tissue limits the acceptability and widespread application of this technique. In this review we discuss possible alternatives cell sources that may be used to repair the brain and spinal cord, with a focus on Sertoli cells, hNT Neurons, bone marrow and umbilical cord blood derived stem cells.
MANAGEMENT OF THE POSTPUBERTAL PATIENT WITH CRYPTORCHIDISM: AN UPDATED ANALYSIS

Purpose: Management of the postpubertal cryptorchid testis depends on patient age at presentation. Based on the belief that the risk of death from surgery first exceeds the risk of death from testis cancer at age 32 years patients younger than 32 years are advised to undergo orchiectomy, while those older than 32 years are advised to remain under close observation. However, the data on which this recommendation is based are now a quarter-century old. During this interval significant improvements have been made in perioperative care and germ cell tumor therapy. We revisited the topic using contemporary data to determine whether and how recommendations on management of the postpubertal cryptorchid testis should be changed.Materials and Methods: Contemporary data on germ cell mortality in the United States were obtained from the National Center for Health Statistics. From these data the lifetime risk of death from germ cell cancer in the general population was calculated for each 5-year interval between ages...
Design tradeoffs in modern software transactional memory systems

Software Transactional Memory (STM) is a generic non-blocking synchronization construct that enables automatic conversion of correct sequential objects into correct concurrent objects. Because it is nonblocking, STM avoids traditional performance and correctness problems due to thread failure, preemption, page faults, and priority inversion.In this paper we compare and analyze two recent object-based STM systems, the DSTM of Herlihy et al. and the FSTM of Fraser, both of which support dynamic transactions, in which the set of objects to be modified is not known in advance. We highlight aspects of these systems that lead to performance tradeoffs for various concurrent data structures. More specifically, we consider object ownership acquisition semantics, concurrent object referencing style, the overhead of ordering and bookkeeping, contention management versus helping semantics, and transaction validation. We demonstrate for each system simple benchmarks on which it outperforms the other by a significant margin. This in turn provides us with a preliminary characterization of the applications for which each system is best suited.
A modified vascularized whole knee joint allotransplantation model in the rat

Previous papers have shown surgical neoangiogenesis to allow long-term bone allotransplant survival without immunosuppression. Whole joint composite tissue allotransplants (CTA) might be treated similarly. A novel rat knee CTA model is described for further study of the roles of neoangiogensis in joint allotransplant survival and adjustment of immunosuppression. Microvascular knee CTA was performed in nine rats across a major histocompatibility barrier with both pedicle repair and implantation of host-derived arteriovenous (“a/v”) bundles. In the control group (N = 3), the pedicle was ligated. Immunosuppression was given daily. Joint mobility, weight-bearing, pedicle patency, bone blood flow, and sprouting from a/v bundles were assessed at 3 weeks. All but the nonrevascularized control knees had full passive motion and full weight bearing. One nutrient pedicle thrombosed prematurely. Blood flow was measurable in transplants with patent nutrient pedicles. Implanted a/v bundles produced new vascular networks on angiography. This new rat microsurgical model permits further study of joint allotransplantation. Patency of both pedicles and implanted a/v bundles was maintained, laying a foundation for future studies. © 2010 Wiley-Liss, Inc. Microsurgery, 2010.
Controls of Nucleosome Positioning in the Human Genome

Nucleosomes are important for gene regulation because their arrangement on the genome can control which proteins bind to DNA. Currently, few human nucleosomes are thought to be consistently positioned across cells; however, this has been difficult to assess due to the limited resolution of existing data. We performed paired-end sequencing of micrococcal nuclease-digested chromatin (MNase–seq) from seven lymphoblastoid cell lines and mapped over 3.6 billion MNase–seq fragments to the human genome to create the highest-resolution map of nucleosome occupancy to date in a human cell type. In contrast to previous results, we find that most nucleosomes have more consistent positioning than expected by chance and a substantial fraction (8.7%) of nucleosomes have moderate to strong positioning. In aggregate, nucleosome sequences have 10 bp periodic patterns in dinucleotide frequency and DNase I sensitivity; and, across cells, nucleosomes frequently have translational offsets that are multiples of 10 bp. We estimate that almost half of the genome contains regularly spaced arrays of nucleosomes, which are enriched in active chromatin domains. Single nucleotide polymorphisms that reduce DNase I sensitivity can disrupt the phasing of nucleosome arrays, which indicates that they often result from positioning against a barrier formed by other proteins. However, nucleosome arrays can also be created by DNA sequence alone. The most striking example is an array of over 400 nucleosomes on chromosome 12 that is created by tandem repetition of sequences with strong positioning properties. In summary, a large fraction of nucleosomes are consistently positioned—in some regions because they adopt favored sequence positions, and in other regions because they are forced into specific arrangements by chromatin remodeling or DNA binding proteins.
The carboxyl-terminal domain of the protein kinase fused can function as a dominant inhibitor of hedgehog signaling

The secreted protein hedgehog (Hh) plays a critical role in the developmental patterning of multiple tissues. In Drosophila melanogaster, a cytosolic multiprotein signaling complex appears necessary for Hh signaling. Genes that encode components of this Hh signaling complex (HSC) were originally identified and characterized based on their genetic interactions with hh, as well as with each other. It is only in recent years that the mechanistic functions of these components have begun to be unraveled. Here, we have investigated the relationship between two components of the HSC, the serine/threonine protein kinase Fused (Fu) and the kinesin-related protein Costal2 (Cos2). We have reconstituted a Fu/Cos2 complex in vitro and shown that Fu is able to directly associate with Cos2, forming a complex whose molecular size is similar to a previously described complex found in Drosophila cell extracts. We have also determined that the carboxyl-terminal domain of Fu is necessary and sufficient for the direct binding of Fu to Cos2. To validate the physiological relevance of this interaction, we overexpressed the carboxyl-terminal domain of Fu in wild-type flies. These flies exhibit a phenotype similar to that seen in fu mutants and consistent with an hh loss-of-function phenotype. We conclude that the carboxyl-terminal domain of Fu can function in a dominant negative manner, by preventing endogenous Fu from binding to Cos2. Thus, we provide the first evidence that Hh signaling can be compromised by targeting the HSC for disruption.
Bacterial diversity of metagenomic and PCR libraries from the Delaware River

To determine whether metagenomic libraries sample adequately the dominant bacteria in aquatic environments, we examined the phylogenetic make-up of a large insert metagenomic library constructed with bacterial DNA from the Delaware River, a polymerase chain reaction (PCR) library of 16S rRNA genes, and community structure determined by fluorescence in situ hybridization (FISH). The composition of the libraries and community structure determined by FISH differed for the major bacterial groups in the river, which included Actinobacteria, beta-proteobacteria and Cytophaga-like bacteria. Beta-proteobacteria were underrepresented in the metagenomic library compared with the PCR library and FISH, while Cytophaga-like bacteria were more abundant in the metagenomic library than in the PCR library and in the actual community according to FISH. The Delaware River libraries contained bacteria belonging to several widespread freshwater clusters, including clusters of Polynucleobacter necessarius, Rhodoferax sp. Bal47 and LD28 beta-proteobacteria, the ACK-m1 and STA2-30 clusters of Actinobacteria, and the PRD01a001B Cytophaga-like bacteria cluster. Coverage of bacteria with > 97% sequence identity was 65% and 50% for the metagenomic and PCR libraries respectively. Rarefaction analysis of replicate PCR libraries and of a library constructed with re-conditioned amplicons indicated that heteroduplex formation did not substantially impact the composition of the PCR library. This study suggests that although it may miss some bacterial groups, the metagenomic approach can sample other groups (e.g. Cytophaga-like bacteria) that are potentially underrepresented by other culture-independent approaches.
Desorption chemical ionization mass spectrometry of epimeric 3-hydroxysteroids and derivatives. Stereoselectivity and nucleophilic substitution with ammonia†

The desorption chemical ionization mass spectra, using ammonia as reagent gas, of several epimeric 3-hydroxysteroids and their ether and carboxylic acid ester derivatives are reported. In the case of steroids possessing a Δ4- or Δ5-3α-benzoate moiety, stereospecific stabilization of the protonated molecular ion [M+H]+ is observed. This behavior is rationalized in terms of interaction of the double bond and the protonated benzoate group at C-3. Nucleophilic substitution by NH3 is observed when a double bond is present in the vicinity of the substitution center. The nature and the stereochemistry of the leaving group influence this substitution reaction. Our results seem to indicate the operation of a two-step mechanism (e.g. SN1 type reaction) rather than a SN2 type mechanism for the formation of the substitution ion [MOR+NH3]+.