877 research outputs found
Micronutrient Distributions in the East Siberian and Laptev Seas during summer 1963
Discusses phosphate, silicate, nitrate, temperature and salinity (T/S) data collected at 140 oceanographic stations occupied by the USCGC Northwind in these seas 7 Aug - 10 Sept 1963, cf No. 92559. These shallow seas deepen gradually toward the shelf edge, the East Siberian toward the E. Precipitation in the excess of evaporation should add ~50 km³/yr of fresh-water to the area; runoff from the seven rivers is ~250 km³/yr for the E Siberian and ~700 km³/yr for the Laptev Sea. Ice ~2 m thick forms in winter, summer melt is ~1 m, the difference compensated by net ice drift out of the area. Surface currents reduce the ice cover near shore in summer, but there is close-pack ice adjacent to Taymyr Peninsula. Annual and seasonal variations in air temperature, wind regime and river runoff obviate steady-state currents and T/S in the region. Silicate concentrations in the surface layer were almost always 5ug-at/liter, those of phosphate or nitrate or both were often so low as to suggest nutrient limitation of phytoplankton production. The nutrients in both seas are compared and discussed in relation to the intense stratification and turbidity of the waters, ice cover, and river discharge. The micronutrient distributions appear to be influenced mainly by summer phytoplankton bloom, respiratory processes, outflow of the Lena, and the different origins of the high-salinity waters found in the two seas.Distribution des microéléments nutritifs dans la mer de Sibérie orientale et dans la mer de Laptev au cours de l'été 1963. L'éclosion estivale du plancton, les processus respiratoires, la décharge du fleuve Léna et les origines diverses des eaux de haute salinité semblent être les facteurs dominants qui influencent la distribution des microéléments nutritifs observée dans la mer de Sibérie orientale et dans la mer de Laptev
Mate-guarding by male mandrills (Mandrillus sphinx) is associated with female MHC genotype
Female choice for male major histocompatibility complex (MHC) genotype has been widely tested, but the relationship between male mating strategies and female MHC genotype has received far less attention. Moreover, few studies of MHC-associated mate choice test for the fitness effects underlying such choice. We examined mate-guarding by male mandrills, a species with intense male–male competition and female offspring care. We developed a statistical model based on 10 years of observations to describe how the probability a female is mate-guarded varies across her sexual cycle, among cycles and among females. We accounted for female rank, parity, and maternal relatedness. We then tested whether the occurrence of mate-guarding is influenced by 1) MHC dissimilarity, 2) female MHC diversity, and 3) specific female MHC genotypes. Finally, we tested for associations between MHC variables and the ratio of neutrophils to lymphocytes in blood samples taken during routine captures. The best-fit models included either MHC dissimilarity (males were more likely to mate-guard more dissimilar females, and there was some evidence of preference for intermediate MHC dissimilarity) or a specific MHC supertype. Four of 11 supertypes investigated were influential and one had a strong negative influence on mate-guarding. We found some evidence that the MHC genotype that attracted the least mate-guarding was disadvantageous in terms of immune function. However, we did not find evidence that MHC diversity was related to immune function. These results suggest that highly competitive males modify their mating behavior based on female MHC genotype, and a possible fitness benefit to mate choice for specific genotypes
Controlling suction by vapour equilibrium technique at different temperatures, application to the determination of the water retention properties of MX80 clay
Problems related to unsaturated soils are frequently encountered in
geotechnical or environmental engineering works. In most cases, for the purpose
of simplicity, the problems are studied by considering the suction effects on
volume change or shear strength under isothermal conditions. Under isothermal
condition, very often, a temperature independent water retention curve is
considered in the analysis, which is obviously a simplification. When the
temperature changes are too significant to be neglected, it is necessary to
account for the thermal effects. In this paper, a method for controlling
suction using the vapour equilibrium technique at different temperatures is
presented. First, calibration of various saturated saline solutions was carried
out from temperature of 20 degrees C to 60 degrees C. A mirror psychrometer was
used for the measurement of relative humidity generated by saturated saline
solutions at different temperatures. The results obtained are in good agreement
with the data from the literature. This information was then used to determine
the water retention properties of MX80 clay, which showed that the retention
curve is shifting down with increasing of temperature
Antibiotic stability over six weeks in aqueous solution at body temperature with and without heat treatment that mimics the curing of bone cement.
Thermal stability is a key property in determining the suitability of an antibiotic agent for local application in the treatment of orthopaedic infections. Despite the fact that long-term therapy is a stated goal of novel local delivery carriers, data describing thermal stability over a long period are scarce, and studies that avoid interference from specific carrier materials are absent from the orthopaedic literature.
In this study, a total of 38 frequently used antibiotic agents were maintained at 37°C in saline solution, and degradation and antibacterial activity assessed over six weeks. The impact of an initial supplementary heat exposure mimicking exothermically curing bone cement was also tested as this material is commonly used as a local delivery vehicle. Antibiotic degradation was assessed by liquid chromatography coupled to mass spectrometry, or by immunoassays, as appropriate. Antibacterial activity over time was determined by the Kirby-Bauer disk diffusion assay.
The heat exposure mimicking curing bone cement had minimal effect on stability for most antibiotics, except for gentamicin which experienced approximately 25% degradation as measured by immunoassay. Beta-lactam antibiotics were found to degrade quite rapidly at 37°C regardless of whether there was an initial heat exposure. Excellent long-term stability was observed for aminoglycosides, glycopeptides, tetracyclines and quinolones under both conditions.
This study provides a valuable dataset for orthopaedic surgeons considering local application of antibiotics, and for material scientists looking to develop next-generation controlled or extended-release antibiotic carriers.Cite this article: E. Samara, T. F. Moriarty, L. A. Decosterd, R. G. Richards, E. Gautier, P. Wahl. Antibiotic stability over six weeks in aqueous solution at body temperature with and without heat treatment that mimics the curing of bone cement. Bone Joint J 2017;6:296-306. DOI: 10.1302/2046-3758.65.BJR-2017-0276.R1
Women, men and coronary heart disease: a review of the qualitative literature
Aim. This paper presents a review of the qualitative literature which examines the experiences of patients with coronary heart disease. The paper also assesses whether the experiences of both female and male patients are reflected in the literature and summarizes key themes.
Background. Understanding patients' experiences of their illness is important for coronary heart disease prevention and education. Qualitative methods are particularly suited to eliciting patients' detailed understandings and perceptions of illness. As much previous research has been 'gender neutral', this review pays particular attention to gender.
Methods. Published papers from 60 qualitative studies were identified for the review through searches in MEDLINE, EMBASE, CINAHL, PREMEDLINE, PsychINFO, Social Sciences Citation Index and Web of Science using keywords related to coronary heart disease.
Findings. Early qualitative studies of patients with coronary heart disease were conducted almost exclusively with men, and tended to generalize from 'male' experience to 'human' experience. By the late 1990s this pattern had changed, with the majority of studies including women and many being conducted with solely female samples. However, many studies that include both male and female coronary heart disease patients still do not have a specific gender focus. Key themes in the literature include interpreting symptoms and seeking help, belief about coronary 'candidates' and relationships with health professionals. The influence of social roles is important: many female patients have difficulties reconciling family responsibilities and medical advice, while male patients worry about being absent from work.
Conclusions. There is a need for studies that compare the experiences of men and women. There is also an urgent need for work that takes masculinity and gender roles into account when exploring the experiences of men with coronary heart disease
The One-loop Open Superstring Massless Five-point Amplitude with the Non-Minimal Pure Spinor Formalism
We compute the massless five-point amplitude of open superstrings using the
non-minimal pure spinor formalism and obtain a simple kinematic factor in pure
spinor superspace, which can be viewed as the natural extension of the
kinematic factor of the massless four-point amplitude. It encodes bosonic and
fermionic external states in supersymmetric form and reduces to existing
bosonic amplitudes when expanded in components, therefore proving their
equivalence. We also show how to compute the kinematic structures involving
fermionic states.Comment: 38 pages, harvmac TeX, v2: fix typo in (4.2) and add referenc
Relação entre a patogenicidade de Schistosoma mansoni em camundongos e a susceptibilidade do molusco vetor: I. Infecciosidade das cercárias e carga de vermes
The recent similarity hypotheses to describe water infiltration into homogeneous soils
Quasars and their host galaxies
This review attempts to describe developments in the fields of quasar and
quasar host galaxies in the past five. In this time period, the Sloan and 2dF
quasar surveys have added several tens of thousands of quasars, with Sloan
quasars being found to z>6. Obscured, or partially obscured quasars have begun
to be found in significant numbers. Black hole mass estimates for quasars, and
our confidence in them, have improved significantly, allowing a start on
relating quasar properties such as radio jet power to fundamental parameters of
the quasar such as black hole mass and accretion rate. Quasar host galaxy
studies have allowed us to find and characterize the host galaxies of quasars
to z>2. Despite these developments, many questions remain unresolved, in
particular the origin of the close relationship between black hole mass and
galaxy bulge mass/velocity dispersion seen in local galaxies.Comment: Review article, to appear in Astrophysics Update
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