818 research outputs found
Temperature dependence of the upper critical field of high-Tc superconductors from isothermal magnetization data. Influence of a temperature dependent Ginzburg-Landau parameter
We show that the scaling procedure, recently proposed for the evaluation of
the temperature variation of the normalized upper critical field of type-II
superconductors, may easily be modified in order to take into account a
possible temperature dependence of the Ginzburg-Landau parameter kappa. As an
example, we consider kappa (T) as it follows from the microscopic theory of
superconductivity.Comment: 7 pages, 4 figur
Updating and amending systematic reviews and systematic maps in environmental management
Systematic reviews and systematic maps aim to provide an overview of the best available evidence to inform research, policy and practice. However, like any form of review, they will require updating periodically to ensure that the most recent evidence has been incorporated. Here we outline two types of review revisions as recognised in medicine: updates and amendments. Updates involve a search for new studies, expanding the evidence base through time. Any other change (e.g. in screening or synthesis) or correction to the original report is an amendment. Decisions as to whether/when it is appropriate to undertake an update or amendment must be made on a case-by-case basis, considering issues such as the reliability and scope of the existing review or map, likely volume of new evidence, resources available, and the likely value of including new information. Careful, consistent reporting is necessary to ensure transparency and repeatability, particularly where there are deviations from the original methods, and authors should highlight key advances relative to the original report. Updating environmental systematic reviews and maps will be an increasingly important activity as the numbers of both primary studies and synthetic reports in the literature continue to grow
Breeding Bird Surveys at Alexandra Fiord, Ellesmere Island, Nunavut (1980â2008)
Long-term monitoring of bird populations in the Arctic is of considerable interest as this area is experiencing rapid climate warming; however, multi-decadal studies in the Canadian High Arctic are rare. Over five summers between 1980 and 2008, we conducted breeding bird surveys by walking transects and mapping territories in a periglacial lowland on east-central Ellesmere Island, Nunavut. In all survey years, snow bunting (Plectrophenax nivalis), Lapland longspur (Calcarius lapponicus), and Baird's sandpiper (Calidris bairdii) were the most abundant species. Over the study period, the assemblage of breeding bird species appears to have changed little, except for an increase in Lapland longspur. In the summer of 2008, we also compared two techniques for censusing territories. We found that spot-mapping, a simple and cost-effective method, produced similar results to the more labour-intensive active-flushing. Spot-mapping is therefore suitable for conducting bird surveys in northern locations where the vegetation is short, the terrain is flat, and the visibility is extensive. In the coming years, it will be important to continue monitoring Arctic birds to determine how climate change is affecting their breeding populations.La surveillance Ă long terme des populations d'oiseaux de l'Arctique revĂȘt un intĂ©rĂȘt considĂ©rable Ă la lumiĂšre du changement climatique rapide que connaĂźt cette rĂ©gion. Cela dit, il faut remarquer que peu d'Ă©tudes Ă©chelonnĂ©es sur plusieurs dĂ©cennies ont Ă©tĂ© rĂ©alisĂ©es dans l'ExtrĂȘme-Arctique canadien. Au cours de cinq Ă©tĂ©s rĂ©partis entre 1980 et 2008, nous avons effectuĂ© le dĂ©nombrement d'oiseaux nicheurs en traversant des transects et en cartographiant des territoires situĂ©s sur les basses terres pĂ©riglaciaires de l'Ăźle d'Ellesmere, au Nunavut. Au cours de toutes les annĂ©es visĂ©es par le dĂ©nombrement, le bruant des neiges (Plectrophenax nivalis), le bruant lapon (Calcarius lapponicus) et le bĂ©casseau de Baird (Calidris bairdii) se sont avĂ©rĂ©s les espĂšces les plus abondantes. Au cours de la pĂ©riode visĂ©e par l'Ă©tude, l'assemblage d'espĂšces d'oiseaux nicheurs semble avoir peu changĂ©, sauf pour ce qui est d'une augmentation de bruants lapons. Ă l'Ă©tĂ© 2008, nous avons Ă©galement comparĂ© deux techniques de recensement des territoires. Nous avons effectivement constatĂ© que la mĂ©thode des plans quadrillĂ©s, une mĂ©thode simple et abordable, donnait des rĂ©sultats semblables Ă la mĂ©thode de dispersion active qui demande beaucoup plus de travail. Par consĂ©quent, la mĂ©thode des plans quadrillĂ©s convient bien Ă la rĂ©alisation de recensements d'oiseaux dans les emplacements nordiques oĂč la vĂ©gĂ©tation est courte, oĂč le terrain est plat et oĂč la visibilitĂ© est vaste. Au cours des annĂ©es Ă venir, il sera important de continuer Ă surveiller les oiseaux de l'Arctique afin de dĂ©terminer quelles sont les incidences du changement climatique sur les populations d'oiseaux nicheurs
Mississippian stratotypes
Working Group on the Mississippian of the U.S.A.Ope
Updating and amending systematic reviews and systematic maps in environmental management
Systematic reviews and systematic maps aim to provide an overview of the best available evidence to inform research, policy and practice. However, like any form of review, they will require updating periodically to ensure that the most recent evidence has been incorporated. Here we outline two types of review revisions as recognised in medicine: updates and amendments. Updates involve a search for new studies, expanding the evidence base through time. Any other change (e.g. in screening or synthesis) or correction to the original report is an amendment. Decisions as to whether/when it is appropriate to undertake an update or amendment must be made on a case-by-case basis, considering issues such as the reliability and scope of the existing review or map, likely volume of new evidence, resources available, and the likely value of including new information. Careful, consistent reporting is necessary to ensure transparency and repeatability, particularly where there are deviations from the original methods, and authors should highlight key advances relative to the original report. Updating environmental systematic reviews and maps will be an increasingly important activity as the numbers of both primary studies and synthetic reports in the literature continue to grow
Neutron Scattering Stiudies
This project covers four principal areas of research: Elastic and inelastic neutron scattering studies in odd-A terbium, thulium and other highly deformed nuclei near A=160 with special regard to interband transitions and to the investigation of the direct-interaction versus the compound-nucleus excitation process in these nuclei. Examination of new, fast photomultiplier tubes suitable for use in a miniaturized neutron-time-of-flight spectrometer. Measurement of certain inelastic cross sections of 238U. Determination of the multiplicity of prompt fission gamma rays in even-A fissile actinides. Energies and mean lives of fission isomers produced by fast fission of even-Z, even-A actinides. Study of the mean life of 7Be in different host matrices and its possible astro-physical significance
CD4-T Cells as a Predictor of Immune Status and Its Outcomes Following Second-Line Combination Antiretroviral Therapy in Adult HIV-1 Infected Patients Attending Apin/Juth HIV Clinic in Jos, Plateau State, Nigeria
Deficiency in immune cell number or activity is a cardinal feature of HIV. Second line antiretroviral therapy is geared towards improving immune cell activity and improving treatment outcomes. More people are now accessing free combination antiretroviral therapy through public health programmes in resource limited settings. There is currently no third line therapy for patients failing second line therapy in most of these programmes and data on effectiveness of second line antiretroviral therapy are limited. To adequately address and prepare for this scenario, critical assessments of the outcomes of second-line cART are needed. This is a retrospective cohort study of patients accessing second line cART at the APIN/ JUTH, Jos adult HIV clinic from 2004 to 2018, to determine the proportion of patients failing second line cART, to evaluate time to immunologic failure, time to lost to follow up and time to death using Kaplan Meier estimates. Immunological failure occurs when there is a fall of CD4 counts to pre-therapy baseline (or below) or 50% fall from the on-treatment peak value (if known) or persistent CD4 levels below 100 cells/mm3 6 months after ART initiation. A total of 285 patients were included in the study, with a mean age of 45±9.5 years. Females where 194 (68.1%) All the patients were on boosted protease inhibitor, the predominant combination antiretroviral therapy for second line regimen was Lopinavir boosted with ritonavir in combination with Tenofovir, Lamivudine and Zidovudine (43.9%). The baseline CD4 count was 134 (IQR 54-272). The CD4 count increased to 339 (IQR213-498) at 72 weeks.  In conclusion, Second line cART immunologic failure rates are low in our cohort and patient stay longer on cART before failure. Keywords: CD4 cells, Immunologic failure, Antiretroviral therapy DOI: 10.7176/JHMN/107-02 Publication date: April 30th 202
Andromeda's Parachute: A Bright Quadruply Lensed Quasar at z = 2.377
We present Keck Cosmic Web Imager spectroscopy of the four putative images of the lensed quasar candidate J014710+463040 recently discovered by Berghea et al. The data verify the source as a quadruply lensed, broad absorption-line quasar having . We detect intervening absorption in the Fe ii λλ2586, 2600, Mg ii λλ2796, 2803, and/or C iv λλ1548, 1550 transitions in eight foreground systems, three of which have redshifts consistent with the photometric-redshift estimate reported for the lensing galaxy (z L â 0.57). The source images probe these absorbers over transverse physical scales of â0.3â22 kpc, permitting assessment of the variation in metal-line equivalent width as a function of sight-line separation. We measure differences in of 50% over the same scales across the majority of sight-line pairs, while C iv absorption exhibits a wide range in differences of â5%â80% within transverse distances of lesssim3 kpc. These spatial variations are consistent with those measured in intervening absorbers detected toward lensed quasars drawn from the literature, in which and vary by â€20% in 35 ± 7% and 47 ± 6% of sight lines separated by 2 quadruply lensed systems for which all four source images are very bright (r = 15.4â17.7 mag) and are easily separated in ground-based seeing conditions. As such, it is an ideal candidate for higher-resolution spectroscopy probing the spatial variation in the kinematic structure and physical state of intervening absorbers
Observation of Parity Violation in the Omega-minus -> Lambda + K-minus Decay
The alpha decay parameter in the process Omega-minus -> Lambda + K-minus has
been measured from a sample of 4.50 million unpolarized Omega-minus decays
recorded by the HyperCP (E871) experiment at Fermilab and found to be [1.78 +/-
0.19(stat) +/- 0.16(syst)]{\times}10^{-2}. This is the first unambiguous
evidence for a nonzero alpha decay parameter, and hence parity violation, in
the Omega-minus -> Lambda + K-minus decay.Comment: 10 pages, 7 figure
Development of Synaptic Boutons in Layer 4 of the Barrel Field of the Rat Somatosensory Cortex: A Quantitative Analysis.
Understanding the structural and functional mechanisms underlying the development of individual brain microcircuits is critical for elucidating their computational properties. As synapses are the key structures defining a given microcircuit, it is imperative to investigate their development and precise structural features. Here, synapses in cortical layer 4 were analyzed throughout the first postnatal month using high-end electron microscopy to generate realistic quantitative 3D models. Besides their overall geometry, the size of active zones and the pools of synaptic vesicles were analyzed. At postnatal day 2 only a few shaft synapses were found, but spine synapses steadily increased with ongoing corticogenesis. From postnatal day 2 to 30 synaptic boutons significantly decreased in size whereas that of active zones remained nearly unchanged despite a reshaping. During the first 2 weeks of postnatal development, a rearrangement of synaptic vesicles from a loose distribution toward a densely packed organization close to the presynaptic density was observed, accompanied by the formation of, first a putative readily releasable pool and later a recycling and reserve pool. The quantitative 3D reconstructions of synapses will enable the comparison of structural and functional aspects of signal transduction thus leading to a better understanding of networks in the developing neocortex
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