1,811 research outputs found
Interpreting the recent results on direct search for dark matter particles in terms of relic neutralino
The most recent results from direct searches for dark matter particles in the
galactic halo are examined in terms of an effective Minimal Supersymmetric
extension of the Standard Model at the electroweak scale without gaugino masses
unification. We show that the annual modulation effect at 8.2 C.L.
recently presented by the DAMA Collaboration, as the result of a combined
analysis of the DAMA/NaI and the DAMA/LIBRA experiments for a total exposure of
0.82 ton yr, fits remarkably well with what expected for relic neutralinos for
a wide variety of WIMP distribution functions. Bounds derivable from other
measurements of direct searches for dark matter particles are analyzed. We
stress the role played by the uncertainties affecting the neutralino--quark
couplings arising from the involved hadronic quantities. We also examine how
present data on cosmic antiprotons can help in constraining the neutralino
configurations selected by the DAMA effect, in connection with the values of
the astrophysical parameters.
Perspectives for measurement of antideuterons possibly produced in the
galactic halo by self--annihilation of neutralinos belonging to the DAMA
configurations are examined. Finally, we discuss how findings at LHC would
impact on these issues.Comment: 18 pages, 10 figures a few minor comments and two references adde
Smart Material Implication Using Spin-Transfer Torque Magnetic Tunnel Junctions for Logic-in-Memory Computing
Smart material implication (SIMPLY) logic has been recently proposed for the design of energy-efficient Logic-in-Memory (LIM) architectures based on non-volatile resistive memory devices. The SIMPLY logic is enabled by adding a comparator to the conventional IMPLY scheme. This allows performing a preliminary READ operation and hence the SET operation only in the case it is actually required. This work explores the SIMPLY logic scheme using nanoscale spin-transfer torque magnetic tunnel junction (STT-MTJ) devices. The performance of the STT-MTJ based SIMPLY architecture is analyzed by varying the load resistor and applied voltages to implement both READ and SET operations, while also investigating the effect of temperature on circuit operation. Obtained results show an existing tradeoff between error rate and energy consumption, which can be effectively managed by properly setting the values of load resistor and applied voltages. In addition, our analysis proves that tracking the temperature dependence of the MTJ properties through a proportional to absolute temperature (PTAT) reference voltage at the input of the comparator is beneficial to mitigate the reliability degradation under temperature variations
Factors affecting the spread of "Bois Noir" disease in north Italy vineyards
To define control strategies for âBois Noirâ disease (BN) it is necessary to know factors favouring its spreading by the vector Hyalesthes obsoletus Signoret. During 2003-2006 a research was carried out in 18 vineyards of a grape-growing area of North Italy to assess the influence of insecticides, applied on grapevine canopies, and environment surrounding the vineyards on disease spreading. The vector population density was higher outside than in the centre of the vineyards. Insecticides applied to grapevine canopies did not significantly influence the vector population level in the centre of the vineyards. The majority of vineyards showed randomized distribution of symptomatic grapevines. Seven vineyards had an aggregate distribution due to an edge effect from a border side with nettle. The incidence of border sides not contiguous to other grapevine rows on vineyard surface was positively related to higher levels of BN. The incidence of border sides with nettle on vineyard surface was positively correlated to disease incidence in the vineyards with aggregate distribution of symptomatic grapevines. All the data support the importance of surrounding vegetation as source of inoculum of BN phytoplasma. Molecular analyses on ribosomal and tuf genes show that 16 out of the 18 vineyards were affected only by BN: in 13 only tuf-type I was identified, in 2 only tuf-type II, in 1 both tuf-types, and in 2 it was not possible to identify the tuf-type of phytoplasmas detected. In the weeds tested only tuftype II phytoplasmas were identified while H. obsoletus was carrying both phytoplasma tuf-types.
Computer Simulation and Fire Drill in an Educational Building
Despite the evolution of computational models for evacuation simulations, there's still some doubt if they can generate accurate results. The objective is to analyze and compare the evacuation times of a fire drill and a computer simulation in an educational building. The method consisted of a fire drill with prior notice of a 4-floor building with classrooms in a public university. A computational model was developed for the same building and population using the evacuation simulation software Pathfinder. The results were that the evacuation times observed in the computer simulation were slightly lower than the times of the fire drill because people covered smaller distances due to the random distribution performed by the Pathfinder software and because in the drill some time was spent for the start of the movement toward the exit, which was estimated at around 30 seconds, while the software was configured for a pre-movement time equal to zero. The use of the computer simulation, therefore, proved to be an effective solution to replace the fire drill, since it allows for the identification of design failures and for the simulation of different scenarios in less time and without the need to mobilize people
Updated analysis of meson-nucleon sigma terms in the perturbative chiral quark model
We present an updated analysis of meson-baryon sigma terms in the
perturbative chiral quark model, which is based on effective chiral Lagrangian.
The new feature concerns the inclusion of excited states in the quark
propagator. Its influence on meson loops is shown to lead in particular for the
pion-nucleon sigma term to an enhancement relevant for the current evaluation
of this quantity. We also determine various flavor combinations of the scalar
nucleon form factors and their respective low-momentum transfer limits.Comment: 26 pages, 10 figures, to be published in Phys Rev
Low Energy Analyzing Powers in Pion-Proton Elastic Scattering
Analyzing powers of pion-proton elastic scattering have been measured at PSI
with the Low Energy Pion Spectrometer LEPS as well as a novel polarized
scintillator target. Angular distributions between 40 and 120 deg (c.m.) were
taken at 45.2, 51.2, 57.2, 68.5, 77.2, and 87.2 MeV incoming pion kinetic
energy for pi+ p scattering, and at 67.3 and 87.2 MeV for pi- p scattering.
These new measurements constitute a substantial extension of the polarization
data base at low energies. Predictions from phase shift analyses are compared
with the experimental results, and deviations are observed at low energies.Comment: 15 pages, 4 figure
49Cr: Towards full spectroscopy up to 4 MeV
The nucleus 49Cr has been studied analysing gamma-gamma coincidences in the
reaction 46Ti(alpha,n)49Cr at the bombarding energy of 12 MeV. The level scheme
has been greatly extended at low excitation energy and several new lifetimes
have been determined by means of the Doppler Shift Attenuation Method.
Shell model calculations in the full pf configuration space reproduce well
negative-parity levels. Satisfactory agreement is obtained for positive parity
levels by extending the configuration space to include a nucleon-hole either in
the 1d3/2 or in the 2s1/2 orbitals.
A nearly one-to-one correspondence is found between experimental and
theoretical levels up to an excitation energy of 4 MeV.
Experimental data and shell model calculations are interpreted in terms of
the Nilsson diagram and the particle-rotor model, showing the strongly coupled
nature of the bands in this prolate nucleus. Nine values of K(pi) are proposed
for the levels observed in this experiment.
As a by-result it is shown that the values of the experimental magnetic
moments in 1f7/2 nuclei are well reproduced without quenching the nucleon
g-factors.Comment: 13 pages, 8 figure
Half-life and spin of 60Mn^g
A value of 0.28 +/- 0.02 s has been deduced for the half-life of the ground
state of 60Mn, in sharp contrast to the previously adopted value of 51 +/- 6 s.
Access to the low-spin 60Mn ground state was accomplished via beta decay of the
0+ 60Cr parent nuclide. New, low-energy states in 60Mn have been identified
from beta-delayed gamma-ray spectroscopy. The new, shorter half-life of 60Mn^g
is not suggestive of isospin forbidden beta decay, and new spin and parity
assignments of 1+ and 4+ have been adopted for the ground and isomeric
beta-decaying states, respectively, of 60Mn.Comment: 13 pages, 5 figures, Accepted for publication in Phys. Rev.
Efeitos da temperatura de secagem do solo e extratores na solubilidade do manganĂȘs.
Temperatura de secagem do solo e das soluçÔes extratoras EDTA, CuCl2 e MgCl2 na solubilidade do manganes
Almond diversity and homozygosity define structure, kinship, inbreeding, and linkage disequilibrium in cultivated germplasm, and reveal genomic associations with nut and seed weight
Almond [Prunus dulcis Miller (D.A. Webb)] is the main tree nut species worldwide. Here, genotyping-by-sequencing (GBS) was applied to 149 almond cultivars from the ex situ collections of the Italian Council for Agricultural Research (CREA) and the Spanish National Research Council (CSIC), leading to the detection of 93,119 single-nucleotide polymorphisms (SNPs). The study of population structure outlined four distinct genetic groups and highlighted diversification between the Mediterranean and Californian gene pools. Data on SNP diversity and runs of homozygosity (ROHs) allowed the definition of kinship, inbreeding, and linkage disequilibrium (LD) decay in almond cultivated germplasm. Four-year phenotypic observations, gathered on 98 cultivars of the CREA collection, were used to perform a genome-wide association study (GWAS) and, for the first time in a crop species, homozygosity mapping (HM), resulting in the identification of genomic associations with nut, shell, and seed weight. Both GWAS and HM suggested that loci controlling nut and seed weight are mostly independent. Overall, this study provides insights on the almond cultivation history and delivers information of major interest for almond genetics and breeding. In a broader perspective, our results encourage the use of ROHs in crop science to estimate inbreeding, choose parental combinations minimizing the risk of inbreeding depression, and identify genomic footprints of selection for specific traits
- âŠ