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Selected AbstractsDisparity in regional and systemic circulatory capacities: do they affect the regulation of the circulation?ACTA PHYSIOLOGICA, Issue 4 2010J. A. L. Calbet Abstract In this review we integrate ideas about regional and systemic circulatory capacities and the balance between skeletal muscle blood flow and cardiac output during heavy exercise in humans. In the first part of the review we discuss issues related to the pumping capacity of the heart and the vasodilator capacity of skeletal muscle. The issue is that skeletal muscle has a vast capacity to vasodilate during exercise [,300 mL (100 g),1 min,1], but the pumping capacity of the human heart is limited to 20,25 L min,1 in untrained subjects and ,35 L min,1 in elite endurance athletes. This means that when more than 7,10 kg of muscle is active during heavy exercise, perfusion of the contracting muscles must be limited or mean arterial pressure will fall. In the second part of the review we emphasize that there is an interplay between sympathetic vasoconstriction and metabolic vasodilation that limits blood flow to contracting muscles to maintain mean arterial pressure. Vasoconstriction in larger vessels continues while constriction in smaller vessels is blunted permitting total muscle blood flow to be limited but distributed more optimally. This interplay between sympathetic constriction and metabolic dilation during heavy whole-body exercise is likely responsible for the very high levels of oxygen extraction seen in contracting skeletal muscle. It also explains why infusing vasodilators in the contracting muscles does not increase oxygen uptake in the muscle. Finally, when ,80% of cardiac output is directed towards contracting skeletal muscle modest vasoconstriction in the active muscles can evoke marked changes in arterial pressure. [source] Genetic modifiers of the physical malformations in velo-cardio-facial syndrome/DiGeorge syndromeDEVELOPMENTAL DISABILITIES RESEARCH REVIEW, Issue 1 2008Vimla S. Aggarwal Abstract Velo-cardio-facial syndrome/DiGeorge syndrome (VCFS/DGS), the most common micro-deletion disorder in humans, is characterized by craniofacial, parathyroid, and thymic defects as well as cardiac outflow tract malformations. Most patients have a similar hemizygous 3 million base pair deletion on 22q11.2. Studies in mouse have shown that Tbx1, a T- box containing transcription factor present on the deleted region, is likely responsible for the etiology of the syndrome. Furthermore, mutations in TBX1 have been found in rare non-deleted patients. Despite having the same sized deletion, most VCFS/DGS patients exhibit significant clinical variability. Stochastic, environmental and genetic factors likely modify the phenotype of patients with the disorder. Here, we review mouse genetics studies, which may help identify possible genetic modifiers for the physical malformations in VCFS/DGS. © 2008 Wiley-Liss, Inc. Dev Disabil Res Rev 2008;14:19,25. [source] The active methanotrophic community in hydromorphic soils changes in response to changing methane concentrationENVIRONMENTAL MICROBIOLOGY, Issue 2 2006Claudia Knief Summary Methanotrophic communities were studied in several periodically water-saturated gleyic soils. When sampled, each soil had an oxic upper layer and consumed methane from the atmosphere (at 1.75 ppmv). In most gleyic soils the Km(app) values for methane were between 70 and 800 ppmv. These are higher than most values observed in dry upland soils, but lower than those measured in wetlands. Based on cultivation-independent retrieval of the pmoA -gene and quantification of partial pmoA gene sequences, type II (Alphaproteobacteria) methanotrophs of the genus Methylocystis spp. were abundant (> 107pmoA target molecules per gram of dry soil). Type I (Gammaproteobacteria) methanotrophs related to the genera Methylobacter and Methylocaldum/Methylococcus were detected in some soils. Six pmoA sequence types not closely related to sequences from cultivated methanotrophs were detected as well, indicating that diverse uncultivated methanotrophs were present. Three Gleysols were incubated under different mixing ratios of 13C-labelled methane to examine 13C incorporation into phospholipid fatty acids (PLFAs). Phospholipid fatty acids typical of type II methanotrophs, 16:0 and 18:1,7c, were labelled with 13C in all soils after incubation under an atmosphere containing 30 ppmv of methane. Incubation under 500 ppmv of methane resulted in labelling of additional PLFAs besides 16:0 and 18:1,7c, suggesting that the composition of the active methanotrophic community changed in response to increased methane supply. In two soils, 16:1 PLFAs typical of type I methanotrophs were strongly labelled after incubation under the high methane mixing ratio only. Type II methanotrophs are most likely responsible for atmospheric methane uptake in these soils, while type I methanotrophs become active when methane is produced in the soil. [source] TEMPORAL PATTERN OF AFRICANIZATION IN A FERAL HONEYBEE POPULATION FROM TEXAS INFERRED FROM MITOCHONDRIAL DNAEVOLUTION, Issue 5 2004M. Alice Pinto Abstract The invasion of Africanized honeybees (Apis mellifera L.) in the Americas provides a window of opportunity to study the dynamics of secondary contact of subspecies of bees that evolved in allopatry in ecologically distinctive habitats of the Old World. We report here the results of an 11-year mitochondrial DNA survey of a feral honeybee population from southern United States (Texas). The mitochondrial haplotype (mitotype) frequencies changed radically during the 11-year study period. Prior to immigration of Africanized honeybees, the resident population was essentially of eastern and western European maternal ancestry. Three years after detection of the first Africanized swarm there was a mitotype turnover in the population from predominantly eastern European to predominantly A. m. scutellata (ancestor of Africanized honeybees). This remarkable change in the mitotype composition coincided with arrival of the parasitic mite Varroa destructor, which was likely responsible for severe losses experienced by colonies of European ancestry. From 1997 onward the population stabilized with most colonies of A. m. scutellata maternal origin. [source] Ubiquitin protein modification and signal transduction: Implications for inflammatory bowel diseasesINFLAMMATORY BOWEL DISEASES, Issue 12 2005Cormac Taylor PhD Abstract A dysregulated immune response to luminal antigen(s) is associated with the development of inflammatory bowel diseases (IBDs). A complex network of inflammatory and immune mediators released by immune and nonimmune cells participate in the physiopathology of IBD. At the molecular level, events leading to the improper use of the signaling grid are likely responsible for the dysregulated activation of various transcription factors and subsequent induction of inflammatory genes. The posttranslational modification of signaling proteins by the ubiquitin system is a critical event in activation or repression of transcription factors. Two important transcriptional pathways in which ubiquitin is central are the nuclear factor-,B and hypoxia inducible factor-1 (HIF-1) pathways, both of which are important components of intestinal homeostasis. In this review, we discuss the role of ubiquitin modification in relation to nuclear factor-,B and HIF-1 signaling and consider its impact on intestinal inflammation. A greater understanding of posttranslational ubiquitin modification may lead to the identification of new therapeutic opportunities for the treatment of IBD. [source] A Kinetic Two-Phase and Equilibrium Solid Solution in Spinel Li4+xTi5O12,ADVANCED MATERIALS, Issue 23 2006M. Wagemaker The zero strain Li4+xTi5O12material as a two-phase system is, in contrast to common knowledge, unstable at room temperature (see figure), and it is fast Li insertion that leads to a kinetically induced effective two-phase reaction. The solid-solution-induced disorder, resulting from the mixed 8a/16c occupation, is most likely responsible for the high rate capabilities in Li4+xTi5O12. [source] Eccrine poroma of the heelINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 6 2000Harvey Lemont A 67-year-old African,American woman had a tender red nodule on the posterior aspect of her left heel of 20 years' duration. The lesion had initially grown quickly to its present size, but subsequently remained unchanged through the years. No previous history of trauma to the area could be elicited. The lesion was not tender or painful, although the patient related some recent discomfort when wearing shoes with high heel counters. Examination revealed a soft, multilobulated, skin-colored nodule, measuring approximately 1.1 cm at its greatest diameter ( Fig. 1), with a rim space or moat ( Fig. 2) surrounding the lesion. Biopsy of the lesion demonstrated a uniform proliferation of basaloid cells exhibiting a sharp demarcation between the adjacent normal epidermis ( Fig. 3). No horn cysts were present. The papillary dermis demonstrated multiple ectatic blood vessels ( Fig. 4) which may be responsible for its reddish appearance. Figure 1 Multilobulated,. red, granulating lesion on the posterior heel Figure 2 Note. the characteristic ,,moat'' surrounding the lesion Figure 3 Biopsy. reveals a proliferation of uniformly small cuboidal cells sharply demarcated from the adjacent normal epidermal cells Figure 4 Ectatic. vessel dilatation most likely responsible for the reddish color of the lesion [source] Spanning the gap: experimental determination of paratenic host specificity of horsehair worms (Nematomorpha: Gordiida)INVERTEBRATE BIOLOGY, Issue 1 2003Ben Hanelt Abstract. Details of the life cycle of freshwater nematomorphs (gordiids) remain unclear. Free-living aquatic larval gordiids must make a critical transition from an epibenthic aquatic environment to terrestrial hosts. In order to identify potential hosts capable of bridging this ecological gap, the specificity of paratenic hosts of three common species of North American gordiids was investigated. All three species were characterized by an identical infection pattern: low host specificity. Gordiids were able to encyst within annelids, mollusks, crustaceans, insects and a vertebrate. Three species of putative host (a turbellarian, a water mite, and a mosquito larva) were not infected with any of the gordiid species. Internal defense reactions (IDR) and feeding behaviors are implicated as preventing infection in these species. Several of the other host species produced either an IDR or an immune reaction to the cysts, although reactions to the cysts were highly variable between species. In most species, IDR did not cause noticeable harm to the encysted larvae. It is proposed that although many species are easily infected with gordiid cysts, most do not act as natural paratenic hosts. For some of these host groups, especially snails, a role as reservoir host is suggested. Of all hosts included in this study, aquatic insects were identified as the hosts likely responsible for spanning the ecological gap and acting as true hosts for gordiids. [source] Marked Improvements in Outcomes of Contemporary Percutaneous Coronary Intervention in Patients with Diabetes MellitusJOURNAL OF INTERVENTIONAL CARDIOLOGY, Issue 6 2006ANDREW M. FREEMAN M.D. We sought to determine if advances in percutaneous coronary intervention (PCI) are associated with better outcomes among patients with diabetes mellitus (DM). Patients with DM enrolled in the National Heart, Lung, and Blood Institute (NHLBI) early PTCA Registry (1985,1986) were compared to those in the subsequent contemporary Dynamic Registry (1999,2002) for in-hospital and one-year cardiovascular outcomes. The study population included 945 adults with DM, 325 from the PTCA Registry and 620 from the Dynamic Registry. Multivariable Cox regression models were built to estimate the risk of clinical events. Dynamic Registry patients were older, had more noncardiac comorbidities, and a lower mean ejection fraction (50.5% vs 57.8%, P , 0.001) compared to the PTCA Registry patients. The incidence of in-hospital mortality (1.9% vs 4.3%, P , 0.05), myocardial infarction (MI) (1.0% vs 7.4%, P , 0.001), and coronary artery bypass grafting (CABG) (0.8% vs 6.2%, P , 0.001) were all significantly lower and independent of the use of stents. One-year adverse events including MI (4.9% vs 11.0%, P , 0.001), CABG (6.4% vs 15.0%, P , 0.001), and need for repeat revascularization (18.7% vs 33.3%, P , 0.001) were all lower in the Dynamic Registry. The relative risk of death at 1 year was significantly less for patients in the Dynamic Registry (RR 0.56, 0.34; 0.92, P = 0.02). Although Dynamic Registry patients with diabetes had more advanced coronary disease, in-hospital and late adverse events were lower. A combination of the use of stents and an increase in adjunctive medical therapy are likely responsible for the observed improvements in outcomes in contemporary PCI. [source] Hierarchical Porous, Self-Supporting La- and F-Codoped TiO2 with High Durability for Continuous-Flow Visible Light PhotocatalysisJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 5 2010Guangxiu Cao Hierarchical porous, self-supporting La- and F-codoped TiO2 with high durability was prepared using a simple polymer template gel. The TiO2 foams were in the anatase phase, with a specific surface area of up to 88 m2/g, and showed a network-like structure containing meso-/macropores. The macropores had a diameter of ca. 300 nm and a wall thickness of 100,300 nm, while the mesopores were narrowly distributed with a mean diameter of around 5.4 nm. The UV-vis diffuse reflection spectra of the sample showed that the presence of intraband gap states was likely responsible for its absorption of visible light. X-ray photoelectron spectroscopy revealed that La2O3 and O,Ti,F bonds were formed. The sample showed an excellent visible light photocatalytic activity and a high durability of photocatalytic activity for the degradation of methylene blue solution. [source] Recruitment of Heliozoa, rhizopods and rotifers from the sediments of an extremely acidic lake during spring and early summerLAKES & RESERVOIRS: RESEARCH AND MANAGEMENT, Issue 2 2008Elanor M. Bell Abstract The goal of this study was to investigate the recruitment of zooplankton from the littoral sediment of Lake 111, an acidic lake in north-east Germany, in April (spring) and June (early summer), and its role in coupling the benthos and the pelagic. Maximum heliozoan and rhizopod recruitment occurred in early summer from sediment cores incubated at ambient water temperatures (20°C). Conversely, recruitment of the rotifer Cephalodella sp. was highest in spring at ambient spring temperatures of 12°C. A combination of passive and active recruitment processes is likely responsible. The seasonal abiotic and biotic sediment characteristics were relatively constant and therefore not likely responsible for the observed temporal recruitment pattern. The sediment water and carbon content ranged from 20 to 50% (mean = 29 ± 6% standard deviation) and 2,12% (mean = 5 ± 2% standard deviation), respectively. Similarly, there was little variation in the chlorophyll- a (mean = 0.2 ± 0.2 µg Chl- a g,1 dry weight , 6.1 ± 3.9 mg Chl- a m,2). The in situ sediment bacterial density (0.82 × 109 ± 0.26 × 109 g,1 dry weight , 1.01 × 109 ± 0.34 × 109 cells cm,3) was high. In contrast, the abundance of zoobenthos and their resting stages was low (< 25 individuals cm,3, and mean of 90 ± 75 cysts cm,3, respectively), with no temporal pattern being observed. Temperature was the only abiotic factor influencing recruitment. This study suggests that, even in relatively young, chemically extreme lakes, the benthos can play an important role in whole lake microbial processes and zooplankton community composition. Such benthic repositories of resting stages potentially provide protection against adverse environmental changes. [source] An investigation of the behavior of Cu and Cr during iron meteorite crystallizationMETEORITICS & PLANETARY SCIENCE, Issue 4 2009Nancy L. CHABOT To investigate the origin of Cu and Cr concentrations observed in these meteorites, a thorough set of solid metal/liquid metal experiments were conducted in the Fe-Ni-S system. In addition to Cu and Cr, partitioning values were also determined for As, Au, Bi, Co, Mo, Ni, Pb, Rh, Ru, Sb, Sn, V, and Zn from the experiments. Experimental results for Cu and Cr showed similar chalcophile partitioning behavior, whereas these elements have differently sloped trends within magmatic iron meteorite groups. Thus, fractional crystallization alone cannot control both the Cu and Cr concentrations in these iron meteorite groups. A simple fractional crystallization model based on our experimental Cu partitioning results was able to match the Cu versus Au trend observed in the S-poor IVB iron meteorite group but not the decreasing Cu versus Au trends in the IIAB and IIIAB groups or the unique S-shaped Cu versus Au trend in the IVA group. However, the crystallization model calculations were found to be very sensitive to the specific choice for the mathematical expression of D(Cu), suggesting that any future refinement of the parameterization of D(Cu) should include a reassessment of the Cu fractional crystallization trends. The Cr versus Au trends in magmatic iron meteorite groups are steeper than those of Cu and not explained by fractional crystallization. Other influences, such as the removal of chromite from the crystallizing system or sampling biases during iron meteorite compositional analyses, are likely responsible for the Cr trends in magmatic iron meteorite groups. [source] The Bassian Isthmus and the major ocean currents of southeast Australia influence the phylogeography and population structure of a southern Australian intertidal barnacle Catomerus polymerus (Darwin)MOLECULAR ECOLOGY, Issue 8 2008KATHERINE L. YORK Abstract Southern Australia is currently divided into three marine biogeographical provinces based on faunal distributions and physical parameters. These regions indicate eastern and western distributions, with an overlap occurring in the Bass Strait in Victoria. However, studies indicate that the boundaries of these provinces vary depending on the species being examined, and in particular on the mode of development employed by that species, be they direct developers or planktonic larvae dispersers. Mitochondrial DNA sequence analysis of the surf barnacle Catomerus polymerus in southern Australia revealed an east,west phylogeographical split involving two highly divergent clades (cytochrome oxidase I 3.5 ± 0.76%, control region 6.7 ± 0.65%), with almost no geographical overlap. Spatial genetic structure was not detected within either clade, indicative of a relatively long-lived planktonic larval phase. Five microsatellite loci indicated that C. polymerus populations exhibit relatively high levels of genetic divergence, and fall into four subregions: eastern Australia, central Victoria, western Victoria and Tasmania, and South Australia. FST values between eastern Australia (from the eastern mitochondrial DNA clade) and the remaining three subregions ranged from 0.038 to 0.159, with other analyses indicating isolation by distance between the subregions of western mitochondrial origin. We suggest that the east,west division is indicative of allopatric divergence resulting from the emergence of the Bassian land-bridge during glacial maxima, preventing gene flow between these two lineages. Subsequently, contemporary ecological conditions, namely the East Australian, Leeuwin, and Zeehan currents and the geographical disjunctions at the Coorong and Ninety Mile Beach are most likely responsible for the four subregions indicated by the microsatellite data. [source] Inferring colonization history from analyses of spatial genetic structure within populations of Pinus strobus and Quercus rubraMOLECULAR ECOLOGY, Issue 3 2006F. A. JONES Abstract Many factors interact to determine genetic structure within populations including adult density, the mating system, colonization history, natural selection, and the mechanism and spatial patterns of gene dispersal. We examined spatial genetic structure within colonizing populations of Quercus rubra seedlings and Pinus strobus juveniles and adults in an aspen,white pine forest in northern Michigan, USA. A 20-year spatially explicit demographic study of the forest enables us to interpret the results in light of recent colonization of the site for both species. We assayed 217 Q. rubra seedlings and 171 P. strobus individuals at 11 polymorphic loci using nine allozyme systems. Plant genotypes and locations were used in an analysis of spatial genetic structure. Q. rubra and P. strobus showed similar observed levels of heterozygosity, but Q. rubra seedlings have less heterozygosity than expected. Q. rubra seedlings show spatial genetic clumping of individuals on a scale to 25 m and levels of genetic relatedness expected from the clumped dispersion of half-siblings. In contrast, P. strobus has low levels of genetic relatedness at the smallest distance class and positive spatial genetic structure at scales < 10 m within the plot. The low density of adult Q. rubra outside the study plot and limited, spatially clumped rodent dispersal of acorns is likely responsible for the observed pattern of spatial genetic structure and the observed heterozygote deficit (i.e. a Wahlund effect). We attribute weaker patterns observed in P. strobus to the longer dispersal distance of seeds and the historical overlap of seed shadows from adults outside of the plot coupled with the overlap of seed shadows from younger, more recently established reproductive adults. The study demonstrates the utility of long-term demographic data in interpreting mechanisms responsible for generating contemporary patterns of genetic structure within populations. [source] The disc-dominated host galaxy of FR-I radio source B2 0722+30MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2009B. H. C. Emonts ABSTRACT We present new observational results that conclude that the nearby radio galaxy B2 0722+30 is one of the very few known disc galaxies in the low-redshift Universe that host a classical double-lobed radio source. In this paper, we use H i observations, deep optical imaging, stellar population synthesis modelling and emission-line diagnostics to study the host galaxy, classify the active galactic nucleus (AGN) and investigate environmental properties under which a radio-loud AGN can occur in this system. Typical for spiral galaxies, B2 0722+30 has a regularly rotating gaseous disc throughout which star formation occurs. Dust heating by the ongoing star formation is likely responsible for the high infrared luminosity of the system. The optical emission-line properties of the central region identify a Low Ionization Nuclear Emission-line Region (LINER)-type nucleus with a relatively low [O iii] luminosity, in particular when compared with the total power of the Fanaroff & Riley type-I radio source that is present in this system. This classifies B2 0722+30 as a classical radio galaxy rather than a typical Seyfert galaxy. The environment of B2 0722+30 is extremely H i -rich, with several nearby interacting galaxies. We argue that a gas-rich interaction involving B2 0722+30 is a likely cause for the triggering of the radio AGN and/or the fact that the radio source managed to escape the optical boundaries of the host galaxy. [source] Protein Kinase Target Discovery From Genome-Wide Messenger RNA Expression ProfilingMOUNT SINAI JOURNAL OF MEDICINE: A JOURNAL OF PERSONALIZED AND TRANSLATIONAL MEDICINE, Issue 4 2010Avi Ma'ayan Abstract Genome-wide messenger RNA profiling provides a snapshot of the global state of the cell under different experimental conditions such as diseased versus normal cellular states. However, because measurements are in the form of quantitative changes in messenger RNA levels, such experimental data does not provide direct understanding of the regulatory molecular mechanisms responsible for the observed changes. Identifying potential cell signaling regulatory mechanisms responsible for changes in gene expression under different experimental conditions or in different tissues has been the focus of many computational systems biology studies. Most popular approaches include promoter analysis, gene ontology, or pathway enrichment analysis, as well as reverse engineering of networks from messenger RNA expression data. Here we present a rational approach for identifying and ranking protein kinases that are likely responsible for observed changes in gene expression. By combining promoter analysis; data from various chromatin immunoprecipitation studies such as chromatin immunoprecipitation sequencing, chromatin immunoprecipitation coupled with paired-end ditag, and chromatin immunoprecipitation-on-chip; protein-protein interactions; and kinase-protein phosphorylation reactions collected from the literature, we can identify and rank candidate protein kinases for knock-down, or other types of functional validations, based on genome-wide changes in gene expression. We describe how protein kinase candidate identification and ranking can be made robust by cross-validation with phosphoproteomics data as well as through a literature-based text-mining approach. In conclusion, data integration can produce robust candidate rankings for understanding cell regulation through identification of protein kinases responsible for gene expression changes, and thus rapidly advancing drug target discovery and unraveling drug mechanisms of action. Mt Sinai J Med 77:345,349, 2010. © 2010 Mount Sinai School of Medicine [source] Taxonomy of pain. (Lehigh Valley Hospital, Center for Pain Management, Allentown, PA) Clin J Pain 2000;16:S114,S117.PAIN PRACTICE, Issue 2 2001Bruce Nicholson: This article discussed the way that research on the pathophysiology of chronic pain has started to challenge the traditional diagnostic and treatment paradigms for the patient with neuropathic pain. It stated that the heterogeneous nature of neuropathic pain indicated that more than one anatomic lesion is most likely responsible for the clinical presentation of a particular syndrome. Conclude that the current taxonomy often falls short of identifying the multifactorial nature of neuropathic pain syndromes and, therefore, may lead to imprecise management of those conditions. It is suggested that an integrated approach to the diagnosis and treatment of neuropathic pain that considers both etiologic factors and possible mechanisms will lead to more effective taxonomy, treatment paradigms, and outcomes. [source] Lepeophtheirus salmonis secretory/excretory products and their effects on Atlantic salmon immune gene regulationPARASITE IMMUNOLOGY, Issue 4 2007M. D. FAST SUMMARY We have previously shown that Lepeophtheirus salmonis produces trypsin and prostaglandin E2 (PGE2) that are most likely responsible for the limited inflammatory response of Atlantic salmon to infection. After removal of the dopamine and PGE2, the immunomodulatory activity of unfractionated and pools of the fractionated secretions was determined by examining the effects of the secretions on Atlantic salmon immune gene expression. Incubation of macrophage-enriched isolates of Atlantic salmon head kidney cells with the unfractionated secretion + PGE2 revealed a significant inhibition of interleukin-1, (IL-1,) and major histocompatibility class I gene expression. Inhibition of lipopolysaccharide-induced IL-1, expression in the Atlantic salmon head kidney cell line (SHK-1) was observed when three pools of the secretory/excretory products were tested. Further purification of products within these pools revealed that fraction 1-2 could account fully for the inhibition of IL-1, expression in SHK-1 cells observed in pooled fraction 1. This study demonstrates that there are other immunomodulatory compounds produced by L. salmonis, in addition to PGE2 and trypsin, that can inhibit the expression of Atlantic salmon immune-related genes in vitro. [source] Analysis of leakage currents in photovoltaic modules under high-voltage bias in the field,PROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 1 2002J. A. del Cueto As photovoltaic modules become more widely disseminated in high-power or utility-power applications, their ability to withstand high voltage relative to ground becomes a reliability issue. Long-term effects of exposure to high-voltage stress in the field are investigated. Starting in early 1998, four commercially available PV modules inaugurated the high-voltage stress test at the Outdoor Test Facility at NREL. Modules representing both crystalline and amorphous silicon technologies were deployed on the high-voltage stress testbed located outdoors in order to simulate and assess operation in high-voltage array configurations. They were biased at positive and negative polarity 600 V at all times,except for 1 min at noon each day, when they were subjected to 2200 V bias,and their leakage currents to ground were monitored continuously. The ubiquitous effects of moisture on leakage conductance are analyzed. Module leakage conductance is found to be thermally activated with a characteristic energy that depends on relative humidity. Separate current paths likely responsible for leakage conductance are analyzed and identified at opposite ends of the relative humidity range. Leakage current data are integrated against time to arrive at accumulated charge due to long-term, high-voltage exposure. Published in 2002 by John Wiley & Sons, Ltd. [source] Problems in determination of skeletal lead burden in archaeological samples: An example from the First African Baptist Church populationAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 4 2008L.E. Wittmers Jr. Abstract Human bone lead content has been demonstrated to be related to socioeconomic status, occupation and other social and environmental correlates. Skeletal tissue samples from 135 individuals from an early nineteenth century Philadelphia cemetery (First African Baptist Church) were studied by electrothermal atomic absorption spectrometry and X-ray fluorescence for lead content. High bone lead levels led to investigation of possible diagenetic effects. These were investigated by several different approaches including distribution of lead within bone by X-ray fluorescence, histological preservation, soil lead concentration and acidity as well as location and depth of burial. Bone lead levels were very high in children, exceeding those of the adult population that were buried in the cemetery, and also those of present day adults. The antemortem age-related increase in bone lead, reported in other studies, was not evidenced in this population. Lead was evenly deposited in areas of taphonomic bone destruction. Synchrotron X-ray fluorescence studies revealed no consistent pattern of lead microdistribution within the bone. Our conclusions are that postmortem diagenesis of lead ion has penetrated these archaeological bones to a degree that makes their original bone lead content irretrievable by any known method. Increased bone porosity is most likely responsible for the very high levels of lead found in bones of newborns and children. Am J Phys Anthropol, 2008. © 2008 Wiley-Liss, Inc. [source] Monitoring of Cochlear Function During Cochlear ImplantationTHE LARYNGOSCOPE, Issue 6 2006Oliver Adunka MD Abstract Objective: To report the feasibility of monitoring cochlear function during cochlear implantation. Study Design: Case report. Setting: Tertiary care referral center. Methods: A child with audiologic features typical of bilateral auditory neuropathy underwent cochlear implantation. The scala tympani was entered inferior and slightly anterior to the round window membrane margin and smooth electrode insertion was achieved. Using single polarity click stimuli, the cochlear microphonic was measured at several steps during surgery. Results: Cochlear microphonics were present at all stages during the implantation process and were clearly distinguished from neural responses by stimulus polarity inversion and constant latencies, despite changes in stimulus level. With the electrode in situ, amplitudes were smaller but persisted until the final measurement at 10 minutes after insertion. At follow-up 2 weeks after surgery, behavioral audiometry results indicated profound hearing loss in the operated ear. Conclusions: This paper demonstrates the feasibility of monitoring cochlear function during cochlear implantation. The routine surgical approach did not appear to adversely affect the functional measurements. Standard size, full electrode insertion did diminish the amplitude of the cochlear microphonics, possibly as a result of intracochlear mechanical impairment. Ultimately, profound hearing loss was documented, indicating that factors other than immediate changes induced by electrode insertion were likely responsible for the loss of cochlear function. [source] Stimulation of Uterine Cell Cytokine Production By Ovarian HormonesAMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 1 2000J.A. DELOIA PROBLEM: Although leukocytes do not possess significant numbers of ovarian steroid hormone receptors, their numbers in the endometrium vary consistently, relative to the menstrual cycle. The possibility that cell types within the endometrium express leukocyte-attracting genes in response to ovarian hormones was investigated. METHOD OF STUDY: Endometrial biopsies were collected 10 days post-leutinizing hormone surge; the cell types were separated and cultured individually for 5 days in the presence of increasing amounts of estrogen or progesterone. Following culture, RNA was collected from cells and reverse-transcription-polymerase chain reaction was used to determine relative levels of gene expression of monocyte chemotactic proteins (MCP)-1, -2, and -3, and interleukin (IL)-12p35 and p40. RESULTS: Although both endometrial stroma and glands were able to make MCP mRNA, steady-state levels of gene expression did not vary significantly relative to hormone treatment. The same was found for the p35 molecule of the IL-12 gene; however, differences were observed for the p40 subunit. CONCLUSIONS: Within the human endometrium, chemokines other than MCP and IL-12 are most likely responsible for cycle-related leukocyte recruitment. [source] Effects of human,carnivore conflict on tiger (Panthera tigris) and prey populations in Lao PDRANIMAL CONSERVATION, Issue 4 2006A. Johnson Abstract Unique to South-east Asia, Lao People's Democratic Republic contains extensive habitat for tigers and their prey within a multiple-use protected area system covering 13% of the country. Although human population density is the lowest in the region, the impact of human occurrence in protected areas on tiger Panthera tigris and prey populations was unknown. We examined the effects of human,carnivore conflict on tiger and prey abundance and distribution in the Nam Et-Phou Louey National Protected Area on the Lao,Vietnam border. We conducted intensive camera-trap sampling of large carnivores and prey at varying levels of human population and monitored carnivore depredation of livestock across the protected area. The relative abundance of large ungulates was low throughout whereas that of small prey was significantly higher where human density was lower. The estimated tiger density for the sample area ranged from 0.2 to 0.7 per 100 km2. Tiger abundance was significantly lower where human population and disturbance were greater. Three factors, commercial poaching associated with livestock grazing followed by prey depletion and competition between large carnivores, are likely responsible for tiger abundance and distribution. Maintaining tigers in the country's protected areas will be dependent on the spatial separation of large carnivores and humans by modifying livestock husbandry practices and enforcing zoning. [source] Evaluation of the sealed-tube low-temperature combustion method for the 13C/12C and 2H/1H ratio determinations of cellulose nitrateCHINESE JOURNAL OF CHEMISTRY, Issue 11 2001Fa-Xiang Tao Abstract Traditionally-suggested combustion time of 1 h at 550°C) with the sealed-tube combustion method for determining the 13C/ 12C ratio of cellulose nitrate or other nitrogen-containing components could produce large negative deviation up to 1°. Three types of cellulose are used to ascertain possible causes. The presence of nitrous oxide (N2O) formed during combustion is most likely responsible for this deviation. Prolongation of the combustion time (at least 5 h at 550°C) and intimate contact between copper oxide and organic matter can greatly improve the analysis precision and effectively reduce this deviation to an acceptable level. Regardless of scattered carbon isotope data, hydrogen isotope data are all reproducible within 2° when this method is coupled with the high temperature uranium reduction method. Thus, care should be taken for determining carbon and nitrogen isotope compositions of nitrogen-containing substances using the low temperature sealed-tube combustion method. [source] | ||||||||||||||||||||||