260,439 research outputs found
Ab-initio simulation and experimental validation of beta-titanium alloys
In this progress report we present a new approach to the ab-initio guided
bottom up design of beta-Ti alloys for biomedical applications using a quantum
mechanical simulation method in conjunction with experiments. Parameter-free
density functional theory calculations are used to provide theoretical guidance
in selecting and optimizing Ti-based alloys with respect to three constraints:
(i) the use of non-toxic alloy elements; (ii) the stabilization of the body
centered cubic beta phase at room temperature; (iii) the reduction of the
elastic stiffness compared to existing Ti-based alloys. Following the
theoretical predictions, the alloys of interest are cast and characterized with
respect to their crystallographic structure, microstructure, texture, and
elastic stiffness. Due to the complexity of the ab initio calculations, the
simulations have been focused on a set of binary systems of Ti with two
different high melting bcc metals, namely, Nb and Mo. Various levels of model
approximations to describe mechanical and thermodynamic properties are tested
and critically evaluated. The experiments are conducted both, on some of the
binary alloys and on two more complex engineering alloy variants, namely,
Ti-35wt.%Nb-7wt.%Zr-5wt.%Ta and a Ti-20wt.%Mo-7wt.%Zr-5wt.%Ta.Comment: 23 pages, progress report on ab initio alloy desig
Virtual Reality Games for Motor Rehabilitation
This paper presents a fuzzy logic based method to track user satisfaction without the need for devices to monitor users physiological conditions. User satisfaction is the key to any product’s acceptance; computer applications and video games provide a unique opportunity to provide a tailored environment for each user to better suit their needs. We have implemented a non-adaptive fuzzy logic model of emotion, based on the emotional component of the Fuzzy Logic Adaptive Model of Emotion (FLAME) proposed by El-Nasr, to estimate player emotion in UnrealTournament 2004. In this paper we describe the implementation of this system and present the results of one of several play tests. Our research contradicts the current literature that suggests physiological measurements are needed. We show that it is possible to use a software only method to estimate user emotion
Teamwork and organizational innovation: the moderating role of the HRM context
Evidence is accumulating on the role of teams in shaping a variety of business outcomes, but our knowledge on the effect of teamwork on organizational innovation is still evolving. This study examines whether the extent to which two staff groups are organized in teams (production staff and management/administrative staff) affects organizational innovation and whether human resource management (HRM) systems, which can be of facilitating or con- straining nature, enhance the teamwork/innovation relationships. Hypotheses were tested with lagged and longitudinal data derived from 18 to 45 organizations from the UK manufacturing sector. Results suggest that the more widespread the use of teamwork in organizations, the higher the level of organizational innovation. Furthermore, this effect depends, particularly for production teams, on the overall quality of the HRM systems that exist in their organizations. Teamwork/innovation relationships are further moderated (for management and administrative teams) by an HRM practice that provides teams with time for thoughtful reflection. Thus, HRM systems can be of more or less facilitating or constraining nature for teams in organizations
Neutrino mixing matrix in the 3-3-1 model with heavy leptons and symmetry
We study the lepton sector in the model based on the local gauge group
which do not contain particles with
exotic electric charges. The seesaw mechanism and discrete symmetry are
introduced into the model to understand why neutrinos are especially light and
the observed pattern of neutrino mixing. The model provides a method for
obtaining the tri-bimaximal mixing matrix in the leading order. A non-zero
mixing angle presents in the modified mixing matrix.Comment: 10 page
Realistic Gluino Axion Model Consistent with Supersymmetry Breaking at the TeV Scale
The recently proposed model of using the dynamical phase of the gluino to
solve the strong CP problem is shown to admit a specific realization in terms
of fundamental singlet superfields, such that the breaking of supersymmetry
occurs only at the TeV scale, despite the large axion scale of 10^{9} to
10^{12} GeV. Phenomenological implications are discussed.Comment: 12 pp, 2 fig
A first step to accelerating fingerprint matching based on deformable minutiae clustering
Fingerprint recognition is one of the most used biometric
methods for authentication. The identification of a query fingerprint requires
matching its minutiae against every minutiae of all the fingerprints
of the database. The state-of-the-art matching algorithms are costly, from
a computational point of view, and inefficient on large datasets. In this
work, we include faster methods to accelerating DMC (the most accurate
fingerprint matching algorithm based only on minutiae). In particular,
we translate into C++ the functions of the algorithm which represent the
most costly tasks of the code; we create a library with the new code and
we link the library to the original C# code using a CLR Class Library
project by means of a C++/CLI Wrapper. Our solution re-implements
critical functions, e.g., the bit population count including a fast C++
PopCount library and the use of the squared Euclidean distance for calculating
the minutiae neighborhood. The experimental results show a
significant reduction of the execution time in the optimized functions of
the matching algorithm. Finally, a novel approach to improve the matching
algorithm, considering cache memory blocking and parallel data processing,
is presented as future work.Universidad de Málaga. Campus de Excelencia Internacional AndalucÃa Tech
The associations of adipokines with selected markers of the renin-angiotensinogen-aldosterone system: the multi-ethnic study of atherosclerosis.
Among obese individuals, increased sympathetic nervous system (SNS) activity results in increased renin and aldosterone production, as well as renal tubular sodium reabsorption. This study determined the associations between adipokines and selected measures of the renin-angiotensinogen-aldosterone system (RAAS). The sample consisted of 1970 men and women from the Multi-Ethnic Study of Atherosclerosis who were free of clinical cardiovascular disease at baseline and had blood assayed for adiponectin, leptin, plasma renin activity (PRA) and aldosterone. The mean age was 64.7 years and 50% were female. The mean (s.d.) PRA and aldosterone were 1.45 (0.56) ng ml(-1) and 150.1 (130.5) pg ml(-1), respectively. After multivariable adjustment, a 1-s.d. increment of leptin was associated with a 0.55 ng ml(-1) higher PRA and 8.4 pg ml(-1) higher aldosterone (P<0.01 for both). Although adiponectin was not significantly associated with PRA levels, the same increment in this adipokine was associated with lower aldosterone levels (-5.5 pg ml(-1), P=0.01). Notably, the associations between aldosterone and both leptin and adiponectin were not materially changed with additional adjustment for PRA. Exclusion of those taking antihypertensive medications modestly attenuated the associations. The associations between leptin and both PRA and aldosterone were not different by gender but were significantly stronger among non-Hispanic Whites and Chinese Americans than African and Hispanic Americans (P<0.01). The findings suggest that both adiponectin and leptin may be relevant to blood pressure regulation via the RAAS, in that the associations appear to be robust to antihypertension medication use and that the associations are likely different by ethnicity
The groupoidal analogue Theta~ to Joyal's category Theta is a test category
We introduce the groupoidal analogue \tilde\Theta to Joyal's cell category
\Theta and we prove that \tilde\Theta is a strict test category in the sense of
Grothendieck. This implies that presheaves on \tilde\Theta model homotopy types
in a canonical way. We also prove that the canonical functor from \Theta to
\tilde\Theta is aspherical, again in the sense of Grothendieck. This allows us
to compare weak equivalences of presheaves on \tilde\Theta to weak equivalences
of presheaves on \Theta. Our proofs apply to other categories analogous to
\Theta.Comment: 41 pages, v2: references added, Remark 7.3 added, v3: metadata
update
Actions for Vacuum Einstein's Equation with a Killing Symmetry
In a space-time with a Killing vector field which is either
everywhere timelike or everywhere spacelike, the collection of all trajectories
of gives a 3-dimension space . Besides the symmetry-reduced action
from that of Einstein-Hilbert, an alternative action of the fields on is
also proposed, which gives the same fields equations as those reduced from the
vacuum Einstein equation on .Comment: 8 pages, the difference between the action we proposed and the
symmetry-reduced action is clarifie
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