394 research outputs found
Altered renal hemodynamics and impaired myogenic responses in the fawn-hooded rat
The present study examined whether an abnormality in the myogenic response
of renal arterioles that impairs autoregulation of renal blood flow (RBF)
and glomerular capillary pressure (PGC) contributes to the development of
renal damage in fawn-hooded hypertensive (FHH) rats. Autoregulation of
whole kidney, cortical, and medullary blood flow and PGC were compared in
young (12 wk old) FHH and fawn-hooded low blood pressure (FHL) rats in
volume-replete and volume-expanded conditions. Baseline RBF, cortical and
medullary blood flow, and PGC were significantly greater in FHH than in
FHL rats. Autoregulation of renal and cortical blood flow was
significantly impaired in FHH rats compared with results obtained in FHL
rats. Myogenically mediated autoregulation of PGC was significantly
greater in FHL than in FHH rats. PGC rose from 46 +/- 1 to 71 +/- 2 mmHg
in response to an increase in renal perfusion pressure from 100 to 150
mmHg in FHH rats, whereas it only increased from 39 +/- 2 to 53 +/- 1 mmHg
in FHL rats. Isolated perfused renal interlobular arteries from FHL rats
constricted by 10% in response to elevations in transmural pressure from
70 to 120 mmHg. In contrast, the diameter of vessels from FHH rats
increased by 15%. These results indicate that the myogenic response of
small renal arteries is altered in FHH rats, and this contributes to an
impaired autoregulation of renal blood flow and elevations in PGC in this
strain
Display blindness? Looking again at the visibility of situated displays using eye tracking
Observational studies of situated displays have suggested that they are rarely looked at, and when they are it is typically only for a short period of time. Using a mobile eye tracker during a realistic shopping task in a shopping center, we show that people look at displays more than would be predicted from these observational studies, but still only short glances and often from quite far away. We characterize the patterns of eye-movements that precede looking at a display and discuss some of the design implications for the design of situated display technologies that are deployed in public space
Impaired autoregulation of renal blood flow in the fawn-hooded rat
The responses to changes in renal perfusion pressure (RPP) were compared
in 12-wk-old fawn-hooded hypertensive (FHH), fawn-hooded low blood
pressure (FHL), and August Copenhagen Irish (ACI) rats to determine
whether autoregulation of renal blood flow (RBF) is altered in the FHH
rat. Mean arterial pressure was significantly higher in conscious,
chronically instrumented FHH rats than in FHL rats (121 +/- 4 vs. 109 +/-
6 mmHg). Baseline arterial pressures measured in
ketamine-Inactin-anesthetized rats averaged 147 +/- 2 mmHg (n = 9) in FHH,
132 +/- 2 mmHg (n = 10) in FHL, and 123 +/- 4 mmHg (n = 9) in ACI rats.
Baseline RBF was significantly higher in FHH than in FHL and ACI rats and
averaged 9.6 +/- 0.7, 7.4 +/- 0.5, and 7.8 +/- 0.9 ml. min-1. g kidney
wt-1, respectively. RBF was autoregulated in ACI and FHL but not in FHH
rats. Autoregulatory indexes in the range of RPPs from 100 to 150 mmHg
averaged 0.96 +/- 0.12 in FHH vs. 0.42 +/- 0.04 in FHL and 0.30 +/- 0.02
in ACI rats. Glomerular filtration rate was 20-30% higher in FHH than in
FHL and ACI rats. Elevations in RPP from 100 to 150 mmHg increased urinary
protein excretion in FHH rats from 27 +/- 2 to 87 +/- 3 microg/min,
whereas it was not significantly altered in FHL or ACI rats. The
percentage of glomeruli exhibiting histological evidence of injury was not
significantly different in the three strains of rats. These results
indicate that autoregulation of RBF is impaired in FHH rats before the
development of glomerulosclerosis and suggest that an abnormality in the
control of renal vascular resistance may contribute to the development of
proteinuria and renal failure in this strain of rats
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Validation of OMI Tropospheric NO2 Observations During INTEX-B and Application to Constrain NOx Emissions Over the Eastern United States and Mexico
We compare tropospheric NO2 column measurements from the Ozone Monitoring Instrument (OMI) aboard the EOS Aura satellite with coincident in situ aircraft measurements on vertical spirals over the southern United States, Mexico, and the Gulf of Mexico during the INTEX-B campaign in March 2006. Good correlation with no significant bias (r2=0.67, slope=0.99±0.17, n=12) is found for the ensemble of comparisons when the aircraft could spiral sufficiently low to sample most of the NO2 column. Urban spirals where large extrapolations were needed below the aircraft floor (1000 ft) showed poorer agreement. We use the OMI observations together with a global chemical transport model (GEOS-Chem) to estimate emissions of nitrogen oxides over the eastern United States and Mexico in March 2006. Comparison to EPA's National Emissions Inventory 1999 (NEI99) calls for a decrease in power plant emissions and an increase in on-road vehicle emissions relative to that inventory. The rise in vehicular emissions is offsetting the reduction in power plant and industry emissions. These findings are consistent with independent assessments. Our OMI-derived emission estimates for Mexico are higher by a factor of 2.0±0.5 than bottom-up emissions, similar to a comparison between the recently released Mexican NEI99 inventory and the bottom-up showing that the Mexican NEI99 inventory is 1.6–1.8× higher.Earth and Planetary SciencesEngineering and Applied Science
Geo-spatial distribution of Brucella melitensis infection in selected local government areas of Katsina and Sokoto States, Nigeria
Brucellosis due to Brucella melitensis infects mostly small ruminants and has been reported to be the most invasive and pathogenic species for humans. A cross-sectional sero-geospatial study was conducted in 4 and 3 Local Government Areas (LGAs) of Katsina and Sokoto States, Nigeria respectively. Sera were analysed using c-ELISA while A Global Positioning System (GPS) receiver was used to take geographic coordinates of all sampling points. Data were analysed with SPSS version 20. Chi-square test was used to measure associations among categorical variables. ArcGIS 10.3 was used to map the geospatial pattern of distribution of B. melitensis. Three-dimensional analysis was also performed using the Inverse Distance Weighted (IDW) interpolation to determine the distribution pattern of B. melitensis in unsampled LGAs. Six (10.52%), 11 (20.0%), 11(2.0%) and 23 (23.0%) sera were positive from Bakori (n=57), Baure (n=56), Daura (n=55) and Funtua (n=101) LGAs of Katsina State respectively while 4 (12.5%), 1 (5.6%), 13 (14.8%) were positive from Illela (n=22), Tambuwal (n=19) and Yabo (n=90) LGAs respectively in Sokoto State were positive for B. melitensis antibodies. All the variables tested were not statistically significant (p ≤ 0.05). The geospatial maps for both States were produced to show the prevalence of B. melitensis using c-ELISA throughout the LGAs sampled and extrapolation was done for other unsampled LGAs. Small ruminants in the study areas harboured antibodies to B. melitensis. The maps may serve as an excellent tool for active surveillance and control strategies for livestock diseases like brucellosis in the study area.Keywords: Brucella melitensis, Small Ruminants, Nigeria, c-ELISA, GI
Energy levels and far-infrared spectroscopy for two electrons in a semiconductor nanoring
The effects of electron-electron interaction of a two-electron nanoring on
the energy levels and far-infrared (FIR) spectroscopy have been investigated
based on a model calculation which is performed within the exactly numerical
diagonalization. It is found that the interaction changes the energy spectra
dramatically, and also shows significant influence on the FIR spectroscopy. The
crossings between the lowest spin-singlet and triplet states induced by the
coulomb interaction are clearly revealed. Our results are related to the
experiment recently carried out by A. Lorke et al. [Phys. Rev. Lett. 84, 2223
(2000)].Comment: 17 pages, 6 figures, revised and accepted by Phys. Rev. B (Dec. 15
Avalanche dynamics, surface roughening and self-organized criticality - experiments on a 3 dimensional pile of rice
We present a two-dimensional system which exhibits features of self-organized
criticality. The avalanches which occur on the surface of a pile of rice are
found to exhibit finite size scaling in their probability distribution. The
critical exponents are = 1.21(2) for the avalanche size distribution and
= 1.99(2) for the cut-off size. Furthermore the geometry of the avalanches
is studied leading to a fractal dimension of the active sites of =
1.58(2). Using a set of scaling relations, we can calculate the roughness
exponent = 0.41(3) and the dynamic exponent = 1.56(8). This result is compared with that obtained from a power
spectrum analysis of the surface roughness, which yields = 0.42(3) and
= 1.5(1) in excellent agreement with those obtained from the scaling
relations.Comment: 7 pages, 8 figures, accepted for publication in PR
Possible origins of macroscopic left-right asymmetry in organisms
I consider the microscopic mechanisms by which a particular left-right (L/R)
asymmetry is generated at the organism level from the microscopic handedness of
cytoskeletal molecules. In light of a fundamental symmetry principle, the
typical pattern-formation mechanisms of diffusion plus regulation cannot
implement the "right-hand rule"; at the microscopic level, the cell's
cytoskeleton of chiral filaments seems always to be involved, usually in
collective states driven by polymerization forces or molecular motors. It seems
particularly easy for handedness to emerge in a shear or rotation in the
background of an effectively two-dimensional system, such as the cell membrane
or a layer of cells, as this requires no pre-existing axis apart from the layer
normal. I detail a scenario involving actin/myosin layers in snails and in C.
elegans, and also one about the microtubule layer in plant cells. I also survey
the other examples that I am aware of, such as the emergence of handedness such
as the emergence of handedness in neurons, in eukaryote cell motility, and in
non-flagellated bacteria.Comment: 42 pages, 6 figures, resubmitted to J. Stat. Phys. special issue.
Major rewrite, rearranged sections/subsections, new Fig 3 + 6, new physics in
Sec 2.4 and 3.4.1, added Sec 5 and subsections of Sec
Vector meson production and nucleon resonance analysis in a coupled-channel approach for energies m_N < sqrt(s) < 2 GeV I: pion-induced results and hadronic parameters
We present a nucleon resonance analysis by simultaneously considering all
pion- and photon-induced experimental data on the final states gamma N, pi N, 2
pi N, eta N, K Lambda, K Sigma, and omega N for energies from the nucleon mass
up to sqrt(s) = 2 GeV. In this analysis we find strong evidence for the
resonances P_{31}(1750), P_{13}(1900), P_{33}(1920), and D_{13}(1950). The
omega N production mechanism is dominated by large P_{11}(1710) and
P_{13}(1900) contributions. In this first part, we present the results of the
pion-induced reactions and the extracted resonance and background properties
with emphasis on the difference between global and purely hadronic fits.Comment: 54 pages, 26 figures, discussion extended, typos corrected,
references updated, to appear in Phys. Rev.
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