1,375 research outputs found
Life history differences across a latitudinal gradient in side-blotched lizards (Uta stansburiana)
Latitudinal variation has long been known to affect life history. Bergmann and Allen made latitudinal “rules” for mammalian anatomy and Lack, Skutch, and Moreau described differences in life history in birds. Trade-offs occur between important life history processes, like self maintenance (immunity) and other expensive but necessary processes. It is likely that trade-offs occur mostly when resources are limited. Side-blotched lizards have a wide geographic range, and more northerly lizards have been observed to have longer lifespans than their southern conspecifics. We hypothesized that northern sideblotched lizards would invest more energy into self-maintenance compared to shorter-lived southern animals
Numerical modeling of bifacial PV string performance: Perimeter effect and influence of uniaxial solar trackers
The bifacial photovoltaic (PV) systems have recently met large interest. The performance of such systems heavily depends on the installation conditions and, in particular, on the albedo radiation collected by the module rear side. Therefore, it is of crucial importance to have an accurate performance model. To date, in the scientific literature, numerous models have been proposed and experimental data collected to study and optimize bifacial PV system performance. Currently, 3D and 2D models of bifacial PV devices exist. Though the former are more mathematically complex, they can lead to more accurate results, since they generally allow to fully consider the main aspects influencing a bifacial PV system performance. Recently, we have proposed and validated through experimental data a 3D model tested as a function of module height, tilt angle, and ground albedo. In this work, through such a model, we studied the role played by the perimeter zones surrounding the PV string, by considering PV strings of 30 or 60 modules. We considered the cases of fixed installation with optimal PV module tilt and of installation with uniaxial horizontal solar tracker. We evaluated the PV energy yield as a function of the size of the perimeter zones for the two cases, i.e., both with and without the solar tracker. In optimal perimeter conditions, we then studied the behavior of bifacial and mono-facial PV strings by varying the geographical location in a large latitude range
Contribution of red blood cells to the compensation for hypocapnic alkalosis through plasmatic strong ion difference variations
Introduction Chloride shift is the movement of chloride between red
blood cells (RBC) and plasma (and vice versa) caused by variations in
pCO2. The aim of our study was to investigate changes in plasmatic
strong ion diff erence (SID) during acute variations in pCO2 and their
possible role in the compensation for hypocapnic alkalosis.Methods Patients admitted in this year to our ICU requiring extracorporeal
CO2 removal were enrolled. Couples of measurements
of gases and electrolytes on blood entering (v) and leaving (a) the
respiratory membrane were analyzed. SID was calculated as [Na+]
+ [K+] + 2[Ca2+] \u2013 [Cl\u2013] \u2013 [Lac\u2013]. Percentage variations in SID (SID%)
were calculated as (SIDv \u2013 SIDa) x 100 / SIDv. The same calculation was
performed for pCO2 (pCO2%). Comparison between v and a values was
performed by paired t test or the signed-rank test, as appropriate.
Results Analysis was conducted on 205 sample-couples of six enrolled
patients. A signifi cant diff erence (P <0.001) between mean values of
v\u2013a samples was observed for pH (7.41 \ub1 0.05 vs. 7.51 \ub1 0.06), pCO2
(48 \ub1 6 vs. 35 \ub1 7 mmHg), [Na+] (136.3 \ub1 4.0 vs. 135.2 \ub1 4.0 mEq/l), [Cl\u2013]
(101.5 \ub1 5.3 vs. 102.8 \ub1 5.2 mEq/l) and therefore SID (39.5 \ub1 4.0 vs.
36.9 \ub1 4.1 mEq/l). pCO2% and SID% signifi cantly correlated (r2 = 0.28,
P <0.001). Graphical representation by quartiles of pCO2% is shown in
Figure 1.
Conclusions As a reduction in SID decreases pH, the observed
movement of anions and cations probably limited the alkalinization
caused by hypocapnia. In this model, the only source of electrolytes
are blood cells (that is, no interstitium and no infl uence of the kidney
is present); it is therefore conceivable to consider the observed
phenomenon as the contribution of RBC for the compensation of acute
hypocapnic alkalosi
Exploring a New Paradigm for Accelerators and Large Experimental Apparatus Control Systems
International audienceThe integration of web technologies and web services has been, in the recent years, one of the major trends in upgrading and developing control systems for accelerators and large experimental apparatuses. Usually, web technologies have been introduced to complement the control systems with smart add-ons and user friendly services or, for instance, to safely allow access to the control system to users from remote sites. In spite of this still narrow spectrum of employment, some software technologies developed for high performance web services, although originally intended and optimized for these particular applications, deserve some features that would allow their deeper integration in a control system and, eventually, use them to develop some of the control system's core components. In this paper we present the conclusion of the preliminary investigations of a new paradigm for an accelerator control system and associated machine data acquisition system (DAQ), based on a synergic combination of network distributed cache memory and a non-relational key/value database. We investigated these technologies with particular interest on performances, namely speed of data storage and retrieve for the network memory, data throughput and queries execution time for the database and, especially, how much this performances can benefit from their inherent scalability. The work has been developed in a collaboration between INFN-LNF and INFN-Roma Tor Vergata
Search for anomalies in the {\nu}e appearance from a {\nu}{\mu} beam
We report an updated result from the ICARUS experiment on the search for
{\nu}{\mu} ->{\nu}e anomalies with the CNGS beam, produced at CERN with an
average energy of 20 GeV and travelling 730 km to the Gran Sasso Laboratory.
The present analysis is based on a total sample of 1995 events of CNGS neutrino
interactions, which corresponds to an almost doubled sample with respect to the
previously published result. Four clear {\nu}e events have been visually
identified over the full sample, compared with an expectation of 6.4 +- 0.9
events from conventional sources. The result is compatible with the absence of
additional anomalous contributions. At 90% and 99% confidence levels the limits
to possible oscillated events are 3.7 and 8.3 respectively. The corresponding
limit to oscillation probability becomes consequently 3.4 x 10-3 and 7.6 x 10-3
respectively. The present result confirms, with an improved sensitivity, the
early result already published by the ICARUS collaboration
Demonstration and Comparison of Operation of Photomultiplier Tubes at Liquid Argon Temperature
Liquified noble gases are widely used as a target in direct Dark Matter
searches. Signals from scintillation in the liquid, following energy deposition
from the recoil nuclei scattered by Dark Matter particles (e.g. WIMPs), should
be recorded down to very low energies by photosensors suitably designed to
operate at cryogenic temperatures. Liquid Argon based detectors for Dark Matter
searches currently implement photo multiplier tubes for signal read-out. In the
last few years PMTs with photocathodes operating down to liquid Argon
temperatures (87 K) have been specially developed with increasing Quantum
Efficiency characteristics. The most recent of these, Hamamatsu Photonics Mod.
R11065 with peak QE up to about 35%, has been extensively tested within the R&D
program of the WArP Collaboration. During these testes the Hamamatsu PMTs
showed superb performance and allowed obtaining a light yield around 7
phel/keVee in a Liquid Argon detector with a photocathodic coverage in the 12%
range, sufficient for detection of events down to few keVee of energy
deposition. This shows that this new type of PMT is suited for experimental
applications, in particular for new direct Dark Matter searches with LAr-based
experiments
Precision measurement of the neutrino velocity with the ICARUS detector in the CNGS beam
During May 2012, the CERN-CNGS neutrino beam has been operated for two weeks
for a total of 1.8 10^17 pot in bunched mode, with a 3 ns narrow width proton
beam bunches, separated by 100 ns. This tightly bunched beam structure allows a
very accurate time of flight measurement of neutrinos from CERN to LNGS on an
event-by-event basis. Both the ICARUS-T600 PMT-DAQ and the CERN-LNGS timing
synchronization have been substantially improved for this campaign, taking
ad-vantage of additional independent GPS receivers, both at CERN and LNGS as
well as of the deployment of the "White Rabbit" protocol both at CERN and LNGS.
The ICARUS-T600 detector has collected 25 beam-associated events; the
corresponding time of flight has been accurately evaluated, using all different
time synchronization paths. The measured neutrino time of flight is compatible
with the arrival of all events with speed equivalent to the one of light: the
difference between the expected value based on the speed of light and the
measured value is tof_c - tof_nu = (0.10 \pm 0.67stat. \pm 2.39syst.) ns. This
result is in agreement with the value previously reported by the ICARUS
collaboration, tof_c - tof_nu = (0.3 \pm 4.9stat. \pm 9.0syst.) ns, but with
improved statistical and systematic errors.Comment: 21 pages, 13 figures, 1 tabl
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