2,988 research outputs found
Monte Carlo simulation of single spin asymmetries in pion-proton collisions
We present Monte Carlo simulations of both the Sivers and the Boer-Mulders
effects in the polarized Drell-Yan
process at the center-of-mass energy GeV reachable at
COMPASS with pion beams of energy 100 GeV. For the Sivers effect, we adopt two
different parametrizations for the Sivers function to explore the statistical
accuracy required to extract unambiguous information on this parton density. In
particular, we verify the possibility of checking its predicted sign change
between Semi-Inclusive Deep-Inelastic Scattering (SIDIS) and Drell-Yan
processes, a crucial test of nonperturbative QCD. For the Boer-Mulders effect,
because of the lack of parametrizations we can make only guesses. The goal is
to explore the possibility of extracting information on the transversity
distribution, the missing piece necessary to complete the knowledge of the
nucleon spin structure at leading twist, and the Boer-Mulders function, which
is related to the long-standing problem of the violation of the Lam-Tung sum
rule in the unpolarized Drell-Yan cross section.Comment: RevTeX, 13 pages, 7 figures included in .eps forma
Effects of azimuth-symmetric acceptance cutoffs on the measured asymmetry in unpolarized Drell-Yan fixed target experiments
Fixed-target unpolarized Drell-Yan experiments often feature an acceptance
depending on the polar angle of the lepton tracks in the laboratory frame.
Typically leptons are detected in a defined angular range, with a dead zone in
the forward region. If the cutoffs imposed by the angular acceptance are
independent of the azimuth, at first sight they do not appear dangerous for a
measurement of the cos(2\phi)-asymmetry, relevant because of its association
with the violation of the Lam-Tung rule and with the Boer-Mulders function. On
the contrary, direct simulations show that up to 10 percent asymmetries are
produced by these cutoffs. These artificial asymmetries present qualitative
features that allow them to mimic the physical ones. They introduce some
model-dependence in the measurements of the cos(2\phi)-asymmetry, since a
precise reconstruction of the acceptance in the Collins-Soper frame requires a
Monte Carlo simulation, that in turn requires some detailed physical input to
generate event distributions. Although experiments in the eighties seem to have
been aware of this problem, the possibility of using the Boer-Mulders function
as an input parameter in the extraction of Transversity has much increased the
requirements of precision on this measurement. Our simulations show that the
safest approach to these measurements is a strong cutoff on the Collins-Soper
polar angle. This reduces statistics, but does not necessarily decrease the
precision in a measurement of the Boer-Mulders function.Comment: 13 pages, 14 figure
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Modulation of attention and stress with arousal: The mental and physical effects of riding a motorcycle
Existing theories suggest that moderate arousal improves selective attention, as would be expected in the context of competitive sports or sensation-seeking activities. Here we investigated how riding a motorcycle, an attention-demanding physical activity, affects sensory processing. To do so, we implemented the passive auditory oddball paradigm and measured the EEG response of participants as they rode a motorcycle, drove a car, and sat at rest. Specifically, we measured the N1 and mismatch negativity to auditory tones, as well as alpha power during periods of no tones. We investigated whether riding and driving modulated non-CNS metrics including heart rate and concentrations of the hormones epinephrine, cortisol, DHEA-S, and testosterone. While participants were riding, we found a decrease in N1 amplitude, increase in mismatch negativity, and decrease in relative alpha power, together suggesting enhancement of sensory processing and visual attention. Riding increased epinephrine levels, increased heart rate, and decreased the ratio of cortisol to DHEA-S. Together, these results suggest that riding increases focus, heightens the brain’s passive monitoring of changes in the sensory environment, and alters HPA axis response. More generally, our findings suggest that selective attention and sensory monitoring seem to be separable neural processes
An harmonic radar prototype for insect tracking in harsh environments
Harmonic entomological radars have been used in the last decades to track small and lightweight passive tags carried by various insects, usually flying at low altitude and over flat terrain. Despite being exploited in many applications, not a lot of progress was achieved in terms of performances over the years. This paper reviews the research work done in this topic throughout the European LIFE project STOPVESPA, from 2015 to 2019. The main objective of LIFE STOPVESPA was to contain the invasive Asian hornet (Vespa velutina) and prevent it from further invading Italy. Among the foreseen activities, a new harmonic radar has been developed as an effective tool to locate the hornets nests to be destroyed. A preliminary prototype, based on a magnetron generator, was tested in 2015, showing a detection range of about 125 m. A first upgrade of this prototype was released in 2016, allowing to increase the detection range up to 150 m. A new approach, based on a solid state power amplifier and a digitally modulated signal, was then adopted for the second prototype developed in 2017 and extensively run in 2018; the detection range raised to 500 m. A last engineered prototype was eventually built for the 2019 summer campaign with additional improvements. This tool has been extensively validated over the last years with the Asian hornet but it has potential for tracking and monitoring many other flying insects
Decreased Polyunsaturated Fatty Acid Content Contributes to Increased Survival in Human Colon Cancer
Among diet
components, some fatty acids are known to affect
several stages of colon carcinogenesis, whereas
others are probably helpful in preventing
tumors. In light of this, our aim was to
determine the composition of fatty acids and the
possible correlation with apoptosis in human
colon carcinoma specimens at different
Duke's stages and to evaluate the effect of
enriching human colon cancer cell line with the
possible reduced fatty acid(s). Specimens of
carcinoma were compared with the corresponding
non-neoplastic mucosa: a significant decrease of
arachidonic acid, PPARα, Bad, and Bax and a significant increase of COX-2,
Bcl-2, and pBad were found. The importance of arachidonic acid in
apoptosis was demonstrated by enriching a Caco-2 cell line with
this fatty acid. It induced apoptosis in a dose- and
time-dependent manner via induction of PPARα that, in turn, decreased COX-2. In conclusion, the
reduced content of arachidonic acid is likely related to
carcinogenic process decreasing the susceptibility of cancer cells
to apoptosis
DISTO data on Kpp
The data from the DISTO Collaboration on the exclusive pp -> p K+ Lambda
production acquired at T_p = 2.85 GeV have been re-analysed in order to search
for a deeply bound K- pp (= X) state, to be formed in the binary process pp ->
K+ X. The preliminary spectra of the DeltaM_{K+} missing-mass and of the M_{p
Lambda} invariant-mass show, for large transverse-momenta of protons and kaons,
a distinct broad peak with a mass M_X = 2265 +- 2 MeV/c^2 and a width Gamma_X =
118 +- 8 MeV/c^2.Comment: 8 pages, 4 figures. Talk presented at the "10th International
Conference on Hypernuclear and Strange Particle Physics" (HYP-X), Tokai,
Ibaraki, Japan, September 14th-18th, 2009. To appear in the proceeding
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