7,116 research outputs found
Applications of TIMS data in agricultural areas and related atmospheric considerations
While much of traditional remote sensing in agricultural research was limited to the visible and reflective infrared, advances in thermal infrared remote sensing technology are adding a dimension to digital image analysis of agricultural areas. The Thermal Infrared Multispectral Scanner (TIMS) an airborne sensor having six bands over the nominal 8.2 to 12.2 m range, offers the ability to calculate land surface emissivities unlike most previous singular broadband sensors. Preliminary findings on the utility of the TIMS for several agricultural applications and related atmospheric considerations are discussed
Searching for Very High Energy Emission from Pulsars Using the High Altitude Water Cherenkov (HAWC) Observatory
There are currently over 160 known gamma-ray pulsars. While most of them are
detected only from space, at least two are now seen also from the ground. MAGIC
and VERITAS have measured the gamma ray pulsed emission of the Crab pulsar up
to hundreds of GeV and more recently MAGIC has reported emission at
TeV. Furthermore, in the Southern Hemisphere, H.E.S.S. has detected the Vela
pulsar above 30 GeV. In addition, non-pulsed TeV emission coincident with
pulsars has been detected by many groups, including the Milagro Collaboration.
These GeV-TeV observations open the possibility of searching for
very-high-energy (VHE, > 100GeV) pulsations from gamma-rays pulsars in the HAWC
field of view.Comment: Presented at the 34th International Cosmic Ray Conference (ICRC2015),
The Hague, The Netherlands. See arXiv:1508.03327 for all HAWC contribution
Improving rainfall nowcasting and urban runoff forecasting through dynamic radar-raingauge rainfall adjustment
The insufficient accuracy of radar rainfall estimates is a major source of uncertainty in short-term quantitative precipitation forecasts (QPFs) and associated urban flood forecasts. This study looks at the possibility of improving QPFs and urban runoff forecasts through the dynamic adjustment of radar rainfall estimates based on raingauge measurements. Two commonly used techniques (Kriging with External Drift (KED) and mean field bias correction) were used to adjust radar rainfall estimates for a large area of the UK (250,000 km2) based on raingauge data. QPFs were produced using original radar and adjusted rainfall estimates as input to a nowcasting algorithm. Runoff forecasts were generated by feeding the different QPFs into the storm water drainage model of an urban catchment in London. The performance of the adjusted precipitation estimates and the associated forecasts was tested using local rainfall and flow records. The results show that adjustments done at too large scales cannot provide tangible improvements in rainfall estimates and associated QPFs and runoff forecasts at small scales, such as those of urban catchments. Moreover, the results suggest that the KED adjusted rainfall estimates may be unsuitable for generating QPFs, as this method damages the continuity of spatial structures between consecutive rainfall fields
Mid-winter lower stratosphere temperatures in the Antarctic vortex: comparison between observations and ECMWF operational model.
International audienceRadiosonde temperature profiles from Belgrano (78° S) and other Antarctic stations have been compared with European Centre for Medium-Range Weather Forecasts (ECMWF) data during the winter of 2003. Results show a bias in the operational model which is height and temperature dependent, being too cold at layers peaking at 80 and 25?30 hPa, and hence resulting in an overestimation of the predicted potential PSC areas. Here we show the results of the comparison by considering the possibility of a bias in the sondes at extremely low temperatures and discuss the potential implications that this bias might have on the ozone depletion computed by Climate Transport Model based on ECMWF temperature fields
Antarctic ozone variability inside the polar vortex estimated from balloon measurements
Thirteen years of ozone soundings at the Antarctic Belgrano II station
(78° S, 34.6° W) have been analysed to establish a
climatology of stratospheric ozone and temperature over the area. The station
is inside the polar vortex during the period of development of chemical ozone
depletion. Weekly periodic profiles provide a suitable database for seasonal
characterization of the evolution of stratospheric ozone, especially valuable
during wintertime, when satellites and ground-based instruments based on
solar radiation are not available. The work is focused on ozone loss rate
variability (August–October) and its recovery (November–December) at
different layers identified according to the severity of ozone loss. The time window selected for the calculations
covers the phase of a quasi-linear ozone reduction, around day 220 (mid-August) to day 273 (end of September). Decrease
of the total ozone column over Belgrano during spring is highly dependent on
the meteorological conditions. Largest depletions (up to 59%) are
reached in coldest years, while warm winters exhibit significantly lower ozone
loss (20%). It has been found that about 11% of the total O<sub>3</sub>
loss, in the layer where maximum depletion occurs, takes place before
sunlight has arrived, as a result of transport to Belgrano of air from a somewhat lower
latitude, near the edge of the polar vortex, providing evidence of mixing
inside the vortex. Spatial homogeneity of the vortex has been examined by
comparing Belgrano results with those previously obtained for South Pole
station (SPS) for the same altitude range and for 9 yr of overlapping data.
Results show more than 25% higher ozone loss rate at SPS than at
Belgrano. The behaviour can be explained taking into account (i) the
transport to both stations of air from a somewhat lower latitude, near the
edge of the polar vortex, where sunlight reappears sooner, resulting in
earlier depletion of ozone, and (ii) the accumulated hours of sunlight, which
become much greater at the South Pole after the spring equinox. According to
the variability of the ozone hole recovery, a clear connection between the
timing of the breakup of the vortex and the monthly ozone content was found.
Minimum ozone concentration of 57 DU in the 12–24 km layer remained in
November, when the vortex is more persistent, while in years when the final
stratospheric warming took place "very early", mean integrated ozone rose
by up to 160–180 DU
Denaturation transition of stretched DNA
We generalize the Poland-Scheraga model to consider DNA denaturation in the
presence of an external stretching force. We demonstrate the existence of a
force-induced DNA denaturation transition and obtain the temperature-force
phase diagram. The transition is determined by the loop exponent for which
we find the new value such that the transition is second order
with in . We show that a finite stretching force
destabilizes DNA, corresponding to a lower melting temperature , in
agreement with single-molecule DNA stretching experiments.Comment: 5 pages, 3 figure
Arginase I in myeloid suppressor cells is induced by COX-2 in lung carcinoma
Myeloid suppressor cells (MSCs) producing high levels of arginase I block T cell function by depleting l-arginine in cancer, chronic infections, and trauma patients. In cancer, MSCs infiltrating tumors and in circulation are an important mechanism for tumor evasion and impair the therapeutic potential of cancer immunotherapies. However, the mechanisms that induce arginase I in MSCs in cancer are unknown. Using the 3LL mouse lung carcinoma, we aimed to characterize these mechanisms. Arginase I expression was independent of T cell–produced cytokines. Instead, tumor-derived soluble factors resistant to proteases induced and maintained arginase I expression in MSCs. 3LL tumor cells constitutively express cyclooxygenase (COX)-1 and COX-2 and produce high levels of PGE2. Genetic and pharmacological inhibition of COX-2, but not COX-1, blocked arginase I induction in vitro and in vivo. Signaling through the PGE2 receptor E-prostanoid 4 expressed in MSCs induced arginase I. Furthermore, blocking arginase I expression using COX-2 inhibitors elicited a lymphocyte-mediated antitumor response. These results demonstrate a new pathway of prostaglandin-induced immune dysfunction and provide a novel mechanism that can help explain the cancer prevention effects of COX-2 inhibitors. Furthermore, an addition of arginase I represents a clinical approach to enhance the therapeutic potential of cancer immunotherapies
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