5,724 research outputs found
Measurement of renal function by calculation of fractional uptake of technetium-99m dimercaptosuccinic acid
BACKGROUND: The purpose of this study was to set up normal values of the
fractional uptake (FU) of technetium-99m dimercaptosuccinic acid in adults and
in the pediatric population, as well as to evaluate the validity of this parameter
at different levels of renal function.
MATERIAL AND METHODS: A total of 86 subjects was divided into seven groups.
In group A there were 23 potential kidney donors and in group B, 18 children in
remission after a first urinary tract infection. Another three groups consisted
of patients with diabetes i.e. group C, seven patients with normal values of albuminuria,
group D, 16 patients with microalbuminuria and group E, five patients with macroalbuminuria.
In group F, there were ten patients with a well-functioning transplanted kidney
and in group G, seven patients with suspected acute rejection. The procedure began
with the quantification of the doses of 99mTc-DMSA to be injected and the measurement
of the empty syringe lying on the gamma camera collimator. Thereafter, four planar
views of the kidneys were acquired three hours after the injection. The counts
from the posterior and anterior views were subtracted for background and corrected
for radioactive decay time and patient thickness. The FU was calculated by the
geometric mean of counts per second from the posterior and anterior view. It was
expressed as a fraction of the injected dose.
RESULTS: The mean values of FU in healthy adults were 0.227 ± 0.077 for
one kidney and 0.454 ± 0.146 for both kidneys. The mean values of FU for the left
and right kidney were 0.225 ± ± 0.071 and 0.229 ± 0.079, respectively. In children,
the mean values were 0.220 ± 0.092 for one kidney and 0.432 ± 0.094 for both kidneys.
The highest values of FU of 0.322 ± 0.078 (0.644 ± 0.138 for both kidneys) were
measured in group C. In group D, FU was 0.185 ± 0.065 (0.361 ± 0.125 for both
kidneys) and in group E 0.082 ± 0.040 (0.163 ± 0.080 total). In patients with
a transplanted kidney, fractional uptake was 0.162 ± ± 0.039 in group F and 0.065
± 0.021 in group G. There was no significant difference in the values of FU between
healthy adults and children. The uptake in group C was 41% higher than in group
A and the difference was statistically significant. In groups D and E, the uptake
was significantly lower than in A. In both groups of patients with transplanted
kidneys, the uptake was significantly lower than in control group. The correlation
between FU and biochemical parameters of renal function [blood urea nitrogen (BUN),
serum creatinine (Cr) and creatinine clearance (CCr)] was significant: FU/BUN
r = –0.86; FU/Cr r = –0.77; FU/CCr r = 0.60.
CONCLUSION: Fractional uptake of99mTc-DMSA could serve as a sensitive
parameter of renal function. The mean values of FU in adults were 0.454 and in
children 0.432. There was no significant difference between values for the left
and right kidney. In diabetes mellitus, fractional uptake correlated well with
the degree of diabetic nephropathy. In patients with a well-functioning transplant,
the uptake was slightly reduced. Low values of fractional uptake in acute rejection
were related to lesions in kidney blood vessels and in tubular cells
Neutrino Mass, Sneutrino Dark Matter and Signals of Lepton Flavor Violation in the MRSSM
We study the phenomenology of mixed-sneutrino dark matter in the Minimal
R-Symmetric Supersymmetric Standard Model (MRSSM). Mixed sneutrinos fit
naturally within the MRSSM, as the smallness (or absence) of neutrino Yukawa
couplings singles out sneutrino A-terms as the only ones not automatically
forbidden by R-symmetry. We perform a study of randomly generated sneutrino
mass matrices and find that (i) the measured value of is well
within the range of typical values obtained for the relic abundance of the
lightest sneutrino, (ii) with small lepton-number-violating mass terms
for the right-handed sneutrinos, random
matrices satisfying the constraint have a decent probability of
satisfying direct detection constraints, and much of the remaining parameter
space will be probed by upcoming experiments, (iii) the terms radiatively generate appropriately small Majorana neutrino
masses, with neutrino oscillation data favoring a mostly sterile lightest
sneutrino with a dominantly mu/tau-flavored active component, and (iv) a
sneutrino LSP with a significant mu component can lead to striking signals of
e-mu flavor violation in dilepton invariant-mass distributions at the LHC.Comment: Revised collider analysis in Sec. 5 after fixing error in particle
spectrum, References adde
A direct method for measuring discounting and QALYs more easily and reliably
Time discounting and quality of life are two important factors in evaluations of medical interventions. The measurement of these two factors is complicated because they interact. Existing methods either simply assume one factor given, based on heuristic assumptions, or invoke complicating extraneous factors, such as risk, that generate extra biases. The authors introduce a method for measuring discounting (and then quality of life) that involves no extraneous factors and that avoids distorting interactions. Their method is considerably simpler and more realistic for subjec
Facile Synthesis of High Quality Graphene Nanoribbons
Graphene nanoribbons have attracted attention for their novel electronic and
spin transport properties1-6, and because nanoribbons less than 10 nm wide have
a band gap that can be used to make field effect transistors. However,
producing nanoribbons of very high quality, or in high volumes, remains a
challenge. Here, we show that pristine few-layer nanoribbons can be produced by
unzipping mildly gas-phase oxidized multiwalled carbon nanotube using
mechanical sonication in an organic solvent. The nanoribbons exhibit very high
quality, with smooth edges (as seen by high-resolution transmission electron
microscopy), low ratios of disorder to graphitic Raman bands, and the highest
electrical conductance and mobility reported to date (up to 5e2/h and 1500
cm2/Vs for ribbons 10-20 nm in width). Further, at low temperature, the
nanoribbons exhibit phase coherent transport and Fabry-Perot interference,
suggesting minimal defects and edge roughness. The yield of nanoribbons was ~2%
of the starting raw nanotube soot material, which was significantly higher than
previous methods capable of producing high quality narrow nanoribbons1. The
relatively high yield synthesis of pristine graphene nanoribbons will make
these materials easily accessible for a wide range of fundamental and practical
applications.Comment: Nature Nanotechnology in pres
Next-to-leading order QCD predictions for production at LHC
We calculate the complete next-to-leading order (NLO) QCD corrections to the
production in association with a jet at the LHC. We study the impacts
of the NLO QCD radiative corrections to the integrated and differential cross
sections and the dependence of the cross section on the
factorization/renormalization scale. We present the transverse momentum
distributions of the final -, Higgs-boson and leading-jet. We find that
the NLO QCD corrections significantly modify the physical observables, and
obviously reduce the scale uncertainty of the LO cross section. The QCD
K-factors can be 1.183 and 1.180 at the and
LHC respectively, when we adopt the inclusive event selection scheme with
, and . Furthermore, we make the comparison between the two scale
choices, and , and find the scale choice seems to be more
appropriate than the fixed scale .Comment: 18 pages, 7 figure
Src Dependent Pancreatic Acinar Injury Can Be Initiated Independent of an Increase in Cytosolic Calcium
Several deleterious intra-acinar phenomena are simultaneously triggered on initiating acute pancreatitis. These culminate in acinar injury or inflammatory mediator generation in vitro and parenchymal damage in vivo. Supraphysiologic caerulein is one such initiator which simultaneously activates numerous signaling pathways including non-receptor tyrosine kinases such as of the Src family. It also causes a sustained increase in cytosolic calcium- a player thought to be crucial in regulating deleterious phenomena. We have shown Src to be involved in caerulein induced actin remodeling, and caerulein induced changes in the Golgi and post-Golgi trafficking to be involved in trypsinogen activation, which initiates acinar cell injury. However, it remains unclear whether an increase in cytosolic calcium is necessary to initiate acinar injury or if injury can be initiated at basal cytosolic calcium levels by an alternate pathway. To study the interplay between tyrosine kinase signaling and calcium, we treated mouse pancreatic acinar cells with the tyrosine phosphatase inhibitor pervanadate. We studied the effect of the clinically used Src inhibitor Dasatinib (BMS-354825) on pervanadate or caerulein induced changes in Src activation, trypsinogen activation, cell injury, upstream cytosolic calcium, actin and Golgi morphology. Pervanadate, like supraphysiologic caerulein, induced Src activation, redistribution of the F-actin from its normal location in the sub-apical area to the basolateral areas, and caused antegrade fragmentation of the Golgi. These changes, like those induced by supraphysiologic caerulein, were associated with trypsinogen activation and acinar injury, all of which were prevented by Dasatinib. Interestingly, however, pervanadate did not cause an increase in cytosolic calcium, and the caerulein induced increase in cytosolic calcium was not affected by Dasatinib. These findings suggest that intra-acinar deleterious phenomena may be initiated independent of an increase in cytosolic calcium. Other players resulting in acinar injury along with the Src family of tyrosine kinases remain to be explored. © 2013 Mishra et al
A coupled optical-thermal-electrical model to predict the performance of hybrid PV/T-CCPC roof-top systems
A crossed compound parabolic concentrator (CCPC) is applied into a photovoltaic/thermal (PV/T) hybrid solar collector, i.e. concentrating PV/T (CPV/T) collector, to develop new hybrid roof-top CPV/T systems. However, to optimise the system configuration and operational parameters as well as to predict their performances, a coupled optical, thermal and electrical model is essential. We establish this model by integrating a number of submodels sourced from literature as well as from our recent work on incidence-dependent optical efficiency, six-parameter electrical model and scaling law for outdoor conditions. With the model, electrical performance and cell temperature are predicted on specific days for the roof-top systems installed in Glasgow, Penryn and Jaen. Results obtained by the proposed model reasonably agree with monitored data and it is also clarified that the systems operate under off-optimal operating condition. Long-term electric performance of the CPV/T systems is estimated as well. In addition, effects of transient terms in heat transfer and diffuse solar irradiance on electric energy are identified and discussed
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Soil Moisture to Runoff (SM2R): A Data-Driven Model for Runoff Estimation Across Poorly Gauged Asian Water Towers Based on Soil Moisture Dynamics
Data Availability Statement: RA5L reanalysis data (Muñoz Sabater, 2019) are available at https://cds.climate.copernicus.eu/cdsapp#!/dataset/10.24381/cds.68d2bb30 . Data sets from the HWSD (Fischer et al., 2008) are accessed at https://www.fao.org/soils-portal/data-hub/soil-maps-and-databases/harmonized-world-soil-database-v12/en/ . Glacier elevation changes (Berthier et al., 2021) are provided at https://doi.org/10.6096/13 , and the RGI 6.0 glacier mask (RGI Consortium, 2017) can be accessed at https://doi.org/10.7265/4m1f-gd79 . Percentages of persistent snow cover in each water tower (Immerzeel et al., 2019) are provided at https://doi.org/10.5281/zenodo.3521933 . Soil moisture estimated from GLDAS NOAH [Beaudoing and Rodell, 2020; Rodell et al., 2004] and CLSM [B. Li et al., 2019; B. Li et al., 2020] land surface models can be accessed at https://disc.gsfc.nasa.gov/datasets/GLDAS_NOAH025_M_2.1/summary and https://disc.gsfc.nasa.gov/datasets/GLDAS_CLSM025_DA1_D_2.2/summary , respectively. Precipitation estimated from the IMERG product (Huffman et al., 2019) can be accessed at https://disc.gsfc.nasa.gov/datasets/GPM_3IMERGDF_06/summary . Runoff estimation results of this study (Li & Long, 2023) are available at https://doi.org/10.5281/zenodo.7505876 .Supporting Information is available online at https://doi.org/10.1029/2022WR033597 .Copyright © 2022 The Author(s) and American Geophysical Union. Almost 2 billion people depend on freshwater provided by the Asian water towers, yet long-term runoff estimation is challenging in this high-mountain region with a harsh environment and scarce observations. Most hydrologic models rely on observed runoff for calibration, and have limited applicability in the poorly gauged Asian water towers. To overcome such limitations, here we propose a novel data-driven model, SM2R (Soil Moisture to Runoff), to simulate monthly runoff based on soil moisture dynamics using reanalysis forcing data. The SM2R model was applied and examined in 20 drainage basins across seven Asian water towers during the past four decades of 1981–2020. Without invoking any observations for calibration, the overall good performance of SM2R-derived runoff (correlation coefficient ≥0.74 and normalized root mean square error ≤0.22 compared to observed runoff at 20 gauges) suggests considerable potential for runoff simulation in poorly gauged basins. Even though the SM2R model is forced by ERA5-Land (ERA5L) reanalysis data, it largely outperforms the ERA5L-estimated runoff across the seven Asian water towers, particularly in basins with widely distributed glaciers and frozen soil. The SM2R approach is highly promising for constraining hydrologic variables from soil moisture information. Our results provide valuable insights for not only long-term runoff estimation over key Asian basins, but also understanding hydrologic processes across poorly gauged regions globally.Second Tibetan Plateau Scientific Expedition and Research program. Grant Number: 2019QZKK0105
National Natural Science Foundation of China. Grant Number: 92047301,92047203
UK Research and Innovation. Grant Number: MR/V022008/
Probing natural SUSY from stop pair production at the LHC
We consider the natural supersymmetry scenario in the framework of the
R-parity conserving minimal supersymmetric standard model (called natural MSSM)
and examine the observability of stop pair production at the LHC. We first scan
the parameters of this scenario under various experimental constraints,
including the SM-like Higgs boson mass, the indirect limits from precision
electroweak data and B-decays. Then in the allowed parameter space we study the
stop pair production at the LHC followed by the stop decay into a top quark
plus a lightest neutralino or into a bottom quark plus a chargino. From
detailed Monte Carlo simulations of the signals and backgrounds, we find the
two decay modes are complementary to each other in probing the stop pair
production, and the LHC with TeV and 100 luminosity is
capable of discovering the stop predicted in natural MSSM up to 450 GeV. If no
excess events were observed at the LHC, the 95% C.L. exclusion limits of the
stop masses can reach around 537 GeV.Comment: 19 pages, 10 figures, version accepted by JHE
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