4,323 research outputs found
A commuting q-analogue of the addition formula for disk polynomials
Starting from the addition formula for -disk polynomials, which is an
identity in non-commuting variables, we establish a basic analogue in commuting
variables of the addition and product formula for disk polynomials. These
contain as limiting cases the addition and product formula for little
-Legendre polynomials. As tends to the addition and product formula
for disk polynomials are recovered
Optimization of Cricket-inspired, Biomimetic Artificial Hair Sensors for Flow Sensing
High density arrays of artificial hair sensors, biomimicking the extremely
sensitive mechanoreceptive filiform hairs found on cerci of crickets have been
fabricated successfully. We assess the sensitivity of these artificial sensors
and present a scheme for further optimization addressing the deteriorating
effects of stress in the structures. We show that, by removing a portion of
chromium electrodes close to the torsional beams, the upward lift at the edges
of the membrane due to the stress, will decrease hence increase the
sensitivity.Comment: Submitted on behalf of EDA Publishing Association
(http://irevues.inist.fr/EDA-Publishing
A systematic review of school-based alcohol and other drug prevention programs
Background: Alcohol use in adolescents constitutes a major public health concern. Europe is the heaviest drinking
region of the world. Several school-based alcohol prevention programs have been developed but it is not clear whether
they are really effective. The present study was aimed at identifying the typology with the best evidence of effectiveness
in European studies. Methods: A systematic search of meta-analyses and/or randomized controlled trials (RCTs) on interventions
school-based prevention programs aimed at preventing alcohol consumption or changing the attitudes to consume
alcohol. Results: A meta-analysis published in 2011 and 12 RCTs more recently published were identified. The
meta-analysis evaluated 53 RCTs but only 11.3% of them were conducted in Europe. Globally, 23 RCTs (43.4%) showed
some evidence of effectiveness, and 30 RCTs (56.6%) did not find significant difference between the groups. According
to the conclusions of the meta-analysis, the Unplugged program should be considered as a practice option in Europe.
Among the other 12 RCTs, 42% were conducted in Europe. Globally, 7 studies (58.3%) achieved positive results, and 5
studies (41.7%) did not find significant differences or produced a mixed pattern of results. Three of the 5 European trials
(60%) used the Unplugged program with positive results. Conclusion: Even if further studies should be conducted to confirm
these results, Unplugged appears to be the prevention project with the best evidence of effectiveness in European
studies
Detailed and large-scale cost/benefit analyses of landslide prevention vs. post-event actions
The main aim of this paper is to
test economic benefits of landslide prevention measures vs. post-event
emergency actions. To this end, detailed- and large-scale analyses were
performed in a training area located in the northeastern Italian pre-Alps
that was hit by an exceptional rainfall event occurred in November 2010. On
the detailed scale, a landslide reactivated after 2010 event was
investigated. Numerical modeling demonstrated that remedial works carried out
after the landslide â water-removal intervention such as a drainage trench
â could have improved slope stability if applied before its occurrence.
Then, a cost/benefit analysis was employed. It defined that prevention would
have been economically convenient compared to a non-preventive and passive
attitude, allowing a 30 % saving relative to total costs. On the large
scale, one of the most affected areas after 2010 event was considered. A
susceptibility analysis was performed using a simple probabilistic model,
which allowed to highlight the main landslide conditioning factors and the
most hazardous and vulnerable sectors. In particular, such low-cost analysis
demonstrated that almost 50 % of landslides occurred after 2010 event
could be foreseen and allowed to roughly quantify benefits from regional
landslide prevention. However, a large-scale approach is insufficient to carry
out a quantitative cost/benefit analysis, for which a detailed case-by-case
risk assessment is needed. The here proposed approaches could be used as a
means of preventive soil protection in not only the investigated case
study but also all those hazardous areas where preventive measures are
needed
Mathematical modeling on gas turbine blades/vanes under variable convective and radiative heat flux with tentative different laws of cooling
In the last twenty years the modeling of heat transfer on gas turbine cascades has been based on computational fluid dynamic and turbulence modeling at sonic transition. The method is called Conjugate Flow and Heat Transfer (CHT). The quest for higher Turbine Inlet Temperature (TIT) to increase electrical efficiency makes radiative transfer the more and more effective in the leading edge and suction/ pressure sides. Calculation of its amount and transfer towards surface are therefore needed. In this paper we decouple convection and radiation load, the first assumed from convective heat transfer data and the second by means of emissivity charts and analytical fits of heteropolar species as CO2 and H2O. Then we propose to solve the temperature profile in the blade through a quasi-two-dimensional power balance in the form of a second order partial differential equation which includes radiation and convection. Real cascades are cooled internally trough cool compressed air, so that we include in the power balance the effect of a heat sink or law of cooling that is up to the designer to test in order to reduce the thermal gradients and material temperature. The problem is numerically solved by means of the Finite Element Method (FEM) and, subsequently, some numerical simulations are also presented
Electronic, dynamical and superconducting properties of CaBeSi
We report first-principles calculations on the normal and superconducting
state of CaBe(x)Si(2-x) (x=1), in the framework of density functional theory
for superconductors (SCDFT). CaBeSi is isostructural and isoelectronic to MgB2
and this makes possible a direct comparison of the electronic and vibrational
properties and the electron-phonon interaction of the two materials. Despite
the many similarities with MgB2 (e.g. sigma bands at the Fermi level and a
larger Fermi surface nesting), according to our calculations CaBeSi has a very
low critical temperature (Tc ~ 0.4 K, consistent with the experiment). CaBeSi
exhibits a complex gap structure, with three gaps at Fermi level: besides the
two sigma and pi gaps, present also in MgB2, the appearance of a third gap is
related to the anisotropy of the Coulomb repulsion, acting in different way on
the bonding and antibonding electronic pi states.Comment: 6 pages, 5 figure
Nutrient availability links mitochondria, apoptosis, and obesity
Mitochondria are the dominant source of the cellular energy requirements through oxidative phosphorylation, but they are also central players in apoptosis. Nutrient availability may have been the main evolutionary driving force behind these opposite mitochondrial functions: production of energy to sustain life and release of apoptotic proteins to trigger cell death. Here, we explore the link between nutrients, mitochondria and apoptosis with known and potential implications for ageârelated decline and metabolic syndromes
Depletion-mode Quantum Dots in Intrinsic Silicon
We report the fabrication and electrical characterization of depletion-mode
quantum dots in a two-dimensional hole gas (2DHG) in intrinsic silicon. We use
fixed charge in a SiO/AlO dielectric stack to induce a 2DHG at the
Si/SiO interface. Fabrication of the gate structures is accomplished with a
single layer metallization process. Transport spectroscopy reveals regular
Coulomb oscillations with charging energies of 10-15 meV and 3-5 meV for the
few- and many-hole regimes, respectively. This depletion-mode design avoids
complex multilayer architectures requiring precision alignment, and allows to
adopt directly best practices already developed for depletion dots in other
material systems. We also demonstrate a method to deactivate fixed charge in
the SiO/AlO dielectric stack using deep ultraviolet light, which
may become an important procedure to avoid unwanted 2DHG build-up in Si MOS
quantum bits.Comment: Accepted to Applied Physics Letters. 5 pages, 3 figure
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