7,113 research outputs found
Properties of low-dimensional collective variables in the molecular dynamics of biopolymers
The description of the dynamics of a complex, high-dimensional system in
terms of a low-dimensional set of collective variables Y can be fruitful if the
low dimensional representation satisfies a Langevin equation with drift and
diffusion coefficients which depend only on Y. We present a computational
scheme to evaluate whether a given collective variable provides a faithful
low-dimensional representation of the dynamics of a high-dimensional system.
The scheme is based on the framework of finite-difference Langevin-equation,
similar to that used for molecular-dynamics simulations. This allows one to
calculate the drift and diffusion coefficients in any point of the
full-dimensional system. The width of the distribution of drift and diffusion
coefficients in an ensemble of microscopic points at the same value of Y
indicates to which extent the dynamics of Y is described by a simple Langevin
equation. Using a simple protein model we show that collective variables often
used to describe biopolymers display a non-negligible width both in the drift
and in the diffusion coefficients. We also show that the associated effective
force is compatible with the equilibrium free--energy calculated from a
microscopic sampling, but results in markedly different dynamical properties
Robust Optimization in Simulation: Taguchi and Response Surface Methodology
Optimization of simulated systems is tackled by many methods, but most methods assume known environments. This article, however, develops a 'robust' methodology for uncertain environments. This methodology uses Taguchi's view of the uncertain world, but replaces his statistical techniques by Response Surface Methodology (RSM). George Box originated RSM, and Douglas Montgomery recently extended RSM to robust optimization of real (non-simulated) systems. We combine Taguchi's view with RSM for simulated systems, and apply the resulting methodology to classic Economic Order Quantity (EOQ) inventory models. Our results demonstrate that in general robust optimization requires order quantities that differ from the classic EOQ.Pareto frontier;bootstrap;Latin hypercube sampling
New Synthetic Endocannabinoid as Anti-Inflammaging Cosmetic Active: an In Vitro Study on a Reconstructed Skin Model
Endocannabinoids have been recently appointed as interesting cosmetic actives in regulating inflammaging, a state of chronic low-grade inflammation, known for being involved in many senescence\u2019s manifestations, included skin aging. The aim of this study was to assess the anti-inflammaging activity of a new synthetic endocannabinoid, Isopalmide\uae, on a reconstructed skin model, on which inflammaging has been reproduced through UVA radiation and light mechanical stress. We tested Isopalmide\uae both as a single active and conveyed in a cosmetic product, in comparison with Anandamide, a well-known natural endocannabinoid with anti-inflammatory action. The anti-inflammaging activity of topically applied products has been assessed, after 6 hours of treatment post-irradiation, through the transcriptional modification of genes involved in the NF-\u3baB pathway and the epigenetic pathway targeting miRs as potential biomarkers of inflammaging: miR-21, miR-126 and miR-146a. The results confirmed the anti-inflammatory action of Anandamide which inhibits NF-\u3baB, while Isopalmide\uae showed its anti-inflammaging activity through the establishment of an inflammatory/anti-inflammatory balance by maintaining NF-\u3baB inactive in the cytoplasm and active in the nucleus. The anti-inflammaging activity was shown also by the cosmetic product containing Isopalmide
A Theoretical Prediction of the Bs-Meson Lifetime Difference
We present the results of a quenched lattice calculation of the operator
matrix elements relevant for predicting the Bs width difference. Our main
result is (\Delta\Gamma_Bs/\Gamma_Bs)= (4.7 +/- 1.5 +/- 1.6) 10^(-2), obtained
from the ratio of matrix elements, R(m_b)=/<\bar
B_s^0|Q_L|B_s^0>=-0.93(3)^(+0.00)_(-0.01). R(m_b) was evaluated from the two
relevant B-parameters, B_S^{MSbar}(m_b)=0.86(2)^(+0.02)_(-0.03) and
B_Bs^{MSbar}(m_b) = 0.91(3)^(+0.00)_(-0.06), which we computed in our
simulation.Comment: 21 pages, 7 PostScript figure
Application of infrared thermography in civil engineering: Limits and drawbacks
Infrared thermography (IRT) is an effective diagnostic methodology for existing buildings monitoring, whose efficiency is however affected by the operator’s technical knowledge. This paper presents experimental research aimed at evaluating the accuracy of IRT temperature measurements with respect to the incorrect setting of five input parameters required to be set by the operator: emissivity, reflected apparent temperature, ambient temperature, relative humidity, and distance. The goal was to highlight how their accurate evaluation and setting affects the thermographic survey and the post-processing stage. To this end, IRT experimental investigations were carried out on materials characterized by different emissivity and surface roughness, such as concrete, granite and steel. The experimentation outcome has pointed out the factors that most affect the temperature measurement error and allowed to quantify the error on the temperature measurements deriving from the incorrect setting of these parameters during the acquisition phase of the thermogram
Dissociation Energies of the Ga2, In2, and GaIn Molecules
The group III metal dimers Ga2 and In2 and the newly identified intermetallic molecule GaIn were investigated in a Knudsen cell-mass spectrometric study of the vapors over gallium–indium alloys. From the all-gas equilibria analyzed by the second-law and third-law methods the following dissociation energies were derived; D00 (Ga2)=110.8±4.9 kJ mol−1, D00 (In2)=74.4±5.7 kJ mol−1, D00 (GaIn)=90.7±3.7 kJ mol−1. The value here measured for the dissociation energy of In2 is discussed and compared with a previous experimental determination and with the results of more recent theoretical investigations
Revision of the Italian magnetic database for the Albegna basin(South Tuscany, Italy)
A comparison between ground level total magnetic field intensity anomaly
map (F) of Italy and the total intensity aeromagnetic map by
ENI/AGIP, had shown that an anomaly pattern for the Albegna basin
(South Tuscany), quite evident from ground measurements, doesn’t show
in the aeromagnetic map. Ligurian units, made of ophiolite blocks
(metagabbros, basalts, serpentinites), intrusives and subordinate volcanic
products, all able to trigger a strong magnetic signal, could not be excluded
in the area, and for this reason the magnetic anomaly estimated by ground
level measurements was not considered unreasonable. In this paper the
result of a magnetic survey finalized to verify the authentic existence of
such a large magnetic total intensity anomaly in the Albegna basin, is reported.
On the basis of the new result, the suspected ground level total intensity
anomaly in the Albegna basin, was demonstrated to be non-existent
and then the Italian Magnetic Database corrected accordingly. Measurements
and procedures that brought to the magnetic elements elaboration
and new anomaly maps for Albegna basin, are shown here
Perturbative and non-perturbative renormalization results of the Chromomagnetic Operator on the Lattice
The Chromomagnetic operator (CMO) mixes with a large number of operators
under renormalization. We identify which operators can mix with the CMO, at the
quantum level. Even in dimensional regularization (DR), which has the simplest
mixing pattern, the CMO mixes with a total of 9 other operators, forming a
basis of dimension-five, Lorentz scalar operators with the same flavor content
as the CMO. Among them, there are also gauge noninvariant operators; these are
BRST invariant and vanish by the equations of motion, as required by
renormalization theory. On the other hand using a lattice regularization
further operators with will mix; choosing the lattice action in a
manner as to preserve certain discrete symmetries, a minimul set of 3
additional operators (all with ) will appear. In order to compute all
relevant mixing coefficients, we calculate the quark-antiquark (2-pt) and the
quark-antiquark-gluon (3-pt) Green's functions of the CMO at nonzero quark
masses. These calculations were performed in the continuum (dimensional
regularization) and on the lattice using the maximally twisted mass fermion
action and the Symanzik improved gluon action. In parallel, non-perturbative
measurements of the matrix element are being performed in simulations
with 4 dynamical () twisted mass fermions and the Iwasaki improved
gluon action.Comment: 7 pages, 1 figure, 3 tables, LATTICE2014 proceeding
Mass Spectrometric and Computational Study of SnPb in the Gas Phase
The SnPb molecule has been identified in a Knudsen effusion mass spectrometry experiment. The direct dissociation reaction and two isomolecular exchange reactions involving the Sn(2) and Pb(2) molecules have been studied, in the 1426-1705 K range of temperatures, using both second and third law procedures. The D(degree)0(SnPb,g) has been derived, for the first time, as (122.6+/-4.0) kJ mol(-1). Density functional and ab initio calculations up to the coupled clusters level of theory were also performed. In addition, the anion dissociation energy D(degree)0(SnPb(-),g) of (179.2+/-4.2) kJ mol(-1) was determined using the D(degree)0(SnPb,g) mass spectrometric value derived in this investigation and literature data
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