923 research outputs found
Multifractal analysis of radar rainfall fields over the area of Rome
A scale-invariance analysis of space and time rainfall events monitored by meteorological radar over the area of Rome (Italy) is proposed. The study of the scale-invariance properties of intense precipitation storms, particularly important in flood forecast and risk mitigation, allows to transfer rainfall information from the large scale predictive meteorological models to the small scale hydrological rainfall-runoff models. <P style="line-height: 20px;"> Precipitation events are monitored using data collected by the polarimetric Doppler radar Polar 55C (ISAC-CNR), located 15 km Southeast from downtown. The meteorological radar provides the estimates of rainfall intensity over an area of about 10 000 km<sup>2</sup> at a resolution of 2×2 km<sup>2</sup> in space and 5 min in time. <P style="line-height: 20px;"> Many precipitation events have been observed from autumn 2001 up to now. A scale-invariance analysis is performed on some of these events with the aim at exploring the multifractal properties and at understanding their dependence on the meteorological large-scale conditions
Forming and preserving aragonite in shear zones: First report of blueschist facies metamorphism in the Jabal Akhdar Dome, Oman Mountains
We report the first occurrence of high-pressure metamorphic aragonite in Precambrian
carbonates of the Jabal Akhdar Dome in the Oman Mountains (northern Oman). We propose
a model for both its formation at blueschist facies conditions and its subsequent preservation
to the surface within the tectonic framework of the Late Cretaceous obduction of
the Semail Ophiolite. Aragonite formed at temperature ∼350 °C and pressure ≥0.9 GPa and
is preserved within mylonitic shear zones and in stretched-fiber dilational veins where the
necessary conditions for its formation and preservation, such as plastic strain accommodation,
fluid-enhanced mineralogical reactions, and an anisotropic permeability structure, were
preferentially met with respect to the surrounding rock. High-strain structural domains are
ideal sites to look for and study prograde and retrograde high-pressure metamorphic histories
in deeply subducted and exhumed terrains
Combustion Modeling Approach for the Optimization of a Temperature Controlled Reactivity Compression Ignition Engine Fueled with Iso-Octane
In this study, an innovative Low Temperature Combustion (LTC) system named Temperature Controlled Reactivity Compression Ignition (TCRCI) is presented, and a numerical optimization of the hardware and the operating parameters is proposed. The studied combustion system aims to reduce the complexity of the Reaction Controlled Compression Ignition engine (RCCI), replacing the direct injection of high reactivity fuel with a heated injection of low reactivity fuel. The combustion system at the actual state of development is presented, and its characteristics are discussed. Hence, it is clear that the performances are highly limited by the actual diesel-derived hardware, and a dedicated model must be designed to progress in the development of this technology. A Computational Fluid Dynamics (CFD) model suitable for the simulation of this type of combustion is proposed, and it is validated with the available experimental operating conditions. The Particle Swarm Optimization (PSO) algorithm was integrated with the Computational Fluid Dynamic (CFD) software to optimize the engine combustion system by means of computational simulation. The operating condition considered has a relatively high load with a fixed fuel mass and compression ratio. The parameters to optimize are the piston bowl geometry, injection parameters and the boosting pressure. The achieved system configuration is characterized by a wider piston bowl and injection angle, and it is able to increase the net efficiency of 3% and to significantly reduce CO emissions from 0.407 to 0.136 mg
Evolution on a Rugged Landscape:Pinning and Aging
Population dynamics on a rugged landscape is studied analytically and
numerically within a simple discrete model for evolution of N individuals in
one-dimensional fitness space. We reduce the set of master equations to a
single Fokker-Plank equation which allows us to describe the dynamics of the
population in terms of thermo-activated Langevin diffusion of a single particle
in a specific random potential. We found that the randomness in the mutation
rate leads to pinning of the population and on average to a logarithmic
slowdown of the evolution, resembling aging phenomenon in spin glass systems.
In contrast, the randomness in the replication rate turns out to be irrelevant
for evolution in the long-time limit as it is smoothed out by increasing
``evolution temperature''. The analytic results are in a good agreement with
numerical simulations.Comment: 4 pages, 3 figures, submitted to Phys. Rev. Let
The Waveform Digitiser of the Double Chooz Experiment: Performance and Quantisation Effects on PhotoMultiplier Tube Signals
We present the waveform digitiser used in the Double Chooz experiment. We
describe the hardware and the custom-built firmware specifically developed for
the experiment. The performance of the device is tested with regards to
digitising low light level signals from photomultiplier tubes and measuring
pulse charge. This highlights the role of quantisation effects and leads to
some general recommendations on the design and use of waveform digitisers.Comment: 14 pages, 8 figures, accepted for publication in JINS
Gastrointestinal strongyles burden monitoring in a flock of Zerasca sheep treated with homeopathy
Introdution
The widespread use of conventional drugs in farm animals has resulted in anthelmintic resistance as well as the contamination of deleterious molecules in animal products and in the environment. Researchers are thus focusing on production systems that rely less on chemicals. The aim of this study was to monitor the gastrointestinal strongyle burden, blood count, body condition scores (BCS), and FAffa MAlan CHArt (FAMACHA) in a local Italian breed of sheep reared in natural conditions.
Methods
The study was carried out in a farm where homeopathy was utilised. Over a one-year period, faeces were sampled six times from ten Zerasca ewes to evaluate the fecal eggs count using a modified McMaster technique. At the same time, blood samples were collected to evaluate white blood cells, red blood cells, hemoglobin, packed cell volume, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, and red cell distribution width. BCS and FAMACHA were also recorded.
Results
Results showed low parasite levels in most of the samples with the highest value in the spring. Blood parameters were within the normal range, with significant fluctuations during the sampling period. BCS values corresponded to an adequate nutritional condition of the animals and FAMACHA scores did not suggest a worrying state of anemia.
Conclusions
In this farm, a thorough monitoring of the gastrointestinal parasite burden together with a BCS and FAMACHA evaluation allowed the amount of chemical treatments to be limited, normally administered twice a year without laboratory tests
Evolution on a smooth landscape
We study in detail a recently proposed simple discrete model for evolution on
smooth landscapes. An asymptotic solution of this model for long times is
constructed. We find that the dynamics of the population are governed by
correlation functions that although being formally down by powers of (the
population size) nonetheless control the evolution process after a very short
transient. The long-time behavior can be found analytically since only one of
these higher-order correlators (the two-point function) is relevant. We compare
and contrast the exact findings derived herein with a previously proposed
phenomenological treatment employing mean field theory supplemented with a
cutoff at small population density. Finally, we relate our results to the
recently studied case of mutation on a totally flat landscape.Comment: Revtex, 15 pages, + 4 embedded PS figure
Use of transperineal fine needle aspiration of seminal vesicles to retrieve sperm in a man with obstructive azoospermia
OBJECTIVE: To report the successful and feasible use of transperineal fine needle aspiration of seminal vesicles (FNASV) for sperm retrieval in obstructive azoospermia.
DESIGN: Case report.
SETTING: Outpatient care in institutional clinic.
PATIENT(S): A 31-year-old man with obstructive azoospermia due to a middle prostatic m\ufcllerian cyst.
INTERVENTION(S): Transperineal FNASV using a coaxial 17-gauge TruGuide needle.
MAIN OUTCOME MEASURE(S): Feasibility of sperm retrieval suitable for future in vitro fertilization.
RESULT(S): Transperineal FNASV made it possible to aspirate 11 mL of fluid with a sperm count of 100 million/mL and 15% motility. This sample was cryopreserved for in vitro fertilization using intracytoplasmic sperm injection.
CONCLUSION(S): Transperineal FNASV using a coaxial needle may be a further method for sperm retrieval to add to the repertoire of assisted reproduction technologies
Mutator Dynamics on a Smooth Evolutionary Landscape
We investigate a model of evolutionary dynamics on a smooth landscape which
features a ``mutator'' allele whose effect is to increase the mutation rate. We
show that the expected proportion of mutators far from equilibrium, when the
fitness is steadily increasing in time, is governed solely by the transition
rates into and out of the mutator state. This results is a much faster rate of
fitness increase than would be the case without the mutator allele. Near the
fitness equilibrium, however, the mutators are severely suppressed, due to the
detrimental effects of a large mutation rate near the fitness maximum. We
discuss the results of a recent experiment on natural selection of E. coli in
the light of our model.Comment: 4 pages, 3 figure
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