5,252 research outputs found
Variability in river temperature, discharge, and energy flux from the Russian panâArctic landmass
We introduce a new Arctic river temperature data set covering 20 gauges in 17 unique Arctic Ocean drainage basins in the Russian panâArctic (ARTâRussia). Warm season 10âday time step data (decades) were collected from Russian archival sources covering a period from 1929 to 2003 with most data falling in the range from the midâ1930s to the early 1990s. The water temperature data were combined with river discharge data to estimate energy flux for all basins and over the Russian panâArctic as a whole. Tests for trend were carried out for water temperature, river discharge, and energy flux. Spatially coherent significant increases in the maximum decadal river temperature were found in the European part of the Russian panâArctic. Several other drainage basins showed significant changes, but there was no strong pattern either in the connections between variables or spatially. The trend in area averaged energy flux for the three largest drainage basins (Ob, Yenisey, Lena) combined was found to be significantly decreasing. We speculate that in the Yenisey basin, this decrease was due to large impoundments of river water. The lack of consistency between temperature and energy flux trends was due to the difference in timing between peaks in river temperature and river discharge. The mean area averaged energy flux from the Russian basins was 0.2 W mâ2. Using this mean we estimated the total energy flux from the entire Russian panâArctic, both gauged and ungauged, to be 82 EJ aâ1
Achieving sustainable irrigation water withdrawals: global impacts on food security and land use
Unsustainable water use challenges the capacity of water resources to ensure food security and continued growth of the economy. Adaptation policies targeting future water security can easily overlook its interaction with other sustainability metrics and unanticipated local responses to the larger-scale policy interventions. Using a global partial equilibrium grid-resolving model SIMPLE-G, and coupling it with the global Water Balance Model, we simulate the consequences of reducing unsustainable irrigation for food security, land use change, and terrestrial carbon. A variety of future (2050) scenarios are considered that interact irrigation productivity with two policy interventionsâ inter-basin water transfers and international commodity market integration. We find that pursuing sustainable irrigation may erode other development and environmental goals due to higher food prices and cropland expansion. This results in over 800â000 more undernourished people and 0.87 GtC additional emissions. Faster total factor productivity growth in irrigated sectors will encourage more aggressive irrigation water use in the basins where irrigation vulnerability is expected to be reduced by inter-basin water transfer. By allowing for a systematic comparison of these alternative adaptations to future irrigation vulnerability, the global gridded modeling approach offers unique insights into the multiscale nature of the water scarcity challenge
Simulations of snow distribution and hydrology in a mountain basin
We applied a version of the Regional HydroâEcologic Simulation System (RHESSys) that implements snow redistribution, elevation partitioning, and windâdriven sublimation to Loch Vale Watershed (LVWS), an alpineâsubalpine Rocky Mountain catchment where snow accumulation and ablation dominate the hydrologic cycle. We compared simulated discharge to measured discharge and the simulated snow distribution to photogrammetrically rectified aerial (remotely sensed) images. Snow redistribution was governed by a topographic similarity index. We subdivided each hillslope into elevation bands that had homogeneous climate extrapolated from observed climate. We created a distributed wind speed field that was used in conjunction with daily measured wind speeds to estimate sublimation. Modeling snow redistribution was critical to estimating the timing and magnitude of discharge. Incorporating elevation partitioning improved estimated timing of discharge but did not improve patterns of snow cover since wind was the dominant controller of areal snow patterns. Simulating windâdriven sublimation was necessary to predict moisture losses
Compensatory embryonic response to allele-specific inactivation of the murine X-linked gene Hcfc1.
Early in female mammalian embryonic development, cells randomly inactivate one of the two X chromosomes to achieve overall equal inactivation of parental X-linked alleles. Hcfc1 is a highly conserved X-linked mouse gene that encodes HCF-1 - a transcriptional co-regulator implicated in cell proliferation in tissue culture cells. By generating a Cre-recombinase inducible Hcfc1 knock-out (Hcfc1(lox)) allele in mice, we have probed the role of HCF-1 in actively proliferating embryonic cells and in cell-cycle re-entry of resting differentiated adult cells using a liver regeneration model. HCF-1 function is required for both extraembryonic and embryonic development. In heterozygous Hcfc1(lox/+) female embryos, however, embryonic epiblast-specific Cre-induced Hcfc1 deletion (creating an Hcfc1(epiKO) allele) around E5.5 is well tolerated; it leads to a mixture of HCF-1-positive and -negative epiblast cells owing to random X-chromosome inactivation of the wild-type or Hcfc1(epiKO) mutant allele. At E6.5 and E7.5, both HCF-1-positive and -negative epiblast cells proliferate, but gradually by E8.5, HCF-1-negative cells disappear owing to cell-cycle exit and apoptosis. Although generating a temporary developmental retardation, the loss of HCF-1-negative cells is tolerated, leading to viable heterozygous offspring with 100% skewed inactivation of the X-linked Hcfc1(epiKO) allele. In resting adult liver cells, the requirement for HCF-1 in cell proliferation was more evident as hepatocytes lacking HCF-1 fail to re-enter the cell cycle and thus to proliferate during liver regeneration. The survival of the heterozygous Hcfc1(epiKO/+) female embryos, even with half the cells genetically compromised, illustrates the developmental plasticity of the post-implantation mouse embryo - in this instance, permitting survival of females heterozygous for an X-linked embryonic lethal allele
Snowmass 2001: Jet Energy Flow Project
Conventional cone jet algorithms arose from heuristic considerations of LO
hard scattering coupled to independent showering. These algorithms implicitly
assume that the final states of individual events can be mapped onto a unique
set of jets that are in turn associated with a unique set of underlying hard
scattering partons. Thus each final state hadron is assigned to a unique
underlying parton. The Jet Energy Flow (JEF) analysis described here does not
make such assumptions. The final states of individual events are instead
described in terms of flow distributions of hadronic energy. Quantities of
physical interest are constructed from the energy flow distribution summed over
all events. The resulting analysis is less sensitive to higher order
perturbative corrections and the impact of showering and hadronization than the
standard cone algorithms.Comment: REVTeX4, 13 pages, 6 figures; Contribution to the P5 Working Group on
QCD and Strong Interactions at Snowmass 200
Gain spectroscopy of a type-II VECSEL chip
Using optical pump-white light probe spectroscopy the gain dynamics is
investigated for a VECSEL chip which is based on a type-II heterostructure. The
active region the chip consists of a GaAs/(GaIn)As/Ga(AsSb)/(GaIn)As/GaAs
multiple quantum well. For this structure, a fully microscopic theory predicts
a modal room temperature gain at a wavelength of 1170 nm, which is confirmed by
experimental spectra. The results show a gain buildup on the type-II chip which
is delayed relative to that of a type-I chip. This slower gain dynamics is
attributed to a diminished cooling rate arising from reduced electron-hole
scattering.Comment: 4 pages, 4 figure
Online Consultations Between General Practitioners and Psychiatrists in the Netherlands:A Qualitative Study
Objective: To examine the nature and scope of questions about psychiatric patient cases submitted by general practitioners (GPs) to an established online consultation platform and to determine if they could have been answered by consulting existing clinical guidelines. Methods: All anonymized psychiatric cases submitted by GPs to the online electronic Prisma platform between September 2018 and November 2019 were examined in a mixed-methods study. Descriptive statistics and qualitative thematic analysis were used, followed by axial coding to arrive at overarching themes to characterize cases. Results: Of the 136 included cases, 44.1% concerned female patients and about half concerned patients aged 31â60 years. Common psychiatric disorders were depression, attention deficit hyperactivity disorder, sleeping problems, sexual disorders, and eating disorders. The first response was usually given within 2 h (interquartile range, 0â14.3 h), with 86% answered within 24 h and 95% within 48 h. Qualitative analysis revealed four themes, namely âtype of question,â âcases in relation to current clinical guidelines,â âcase complexityâ and âthe doctor being pressured.â Type of question comprised diagnostic, therapeutic, and referral questions. Notably, for 44.1% of questions no current clinical guidelines was present and 46.3% of cases were deemed complex in nature. GPs were willing to share their experiences of coping with being pressured by patients. Conclusion: The findings of this study support the potential for an online electronic consultation platform to facilitate feasible and useful interprofessional consultation between GPs and psychiatrists for a broad range mental illnesses and questions of varying complexity
Types of Stickiness in BHV Phylogenetic Tree Spaces and Their Degree
It has been observed that the sample mean of certain probability
distributions in Billera-Holmes-Vogtmann (BHV) phylogenetic spaces is confined
to a lower-dimensional subspace for large enough sample size. This non-standard
behavior has been called stickiness and poses difficulties in statistical
applications when comparing samples of sticky distributions. We extend previous
results on stickiness to show the equivalence of this sampling behavior to
topological conditions in the special case of BHV spaces. Furthermore, we
propose to alleviate statistical comparision of sticky distributions by
including the directional derivatives of the Fr\'echet function: the degree of
stickiness.Comment: 8 Pages, 1 Figure, conference submission to GSI 202
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