429 research outputs found
Strongly correlated fermions with nonlinear energy dispersion and spontaneous generation of anisotropic phases
Using the bosonization approach we study fermionic systems with a nonlinear
dispersion relation in dimension d>2. We explicitly show how the band curvature
gives rise to interaction terms in the bosonic version of the model. Although
these terms are perturbatively irrelevant in relation to the Landau Fermi
liquid fixed point, they become relevant perturbations when instabilities take
place. Using a coherent state path integral technique we built up the effective
action that governs the dynamics of the Fermi surface fluctuations. We consider
the combined effect of fermionic interactions and band curvature on possible
anisotropic phases triggered by negative Landau parameters. In particular we
study in some detail the phase diagram for the isotropic/nematic/hexatic
quantum phase transition.Comment: RevTeX4, 9 pages, 2 eps figures, Final version as appeared in
Phys.Rev.
Using Preferred Outcome Distributions to Estimate Value and Probability Weighting Functions in Decisions under Risk
In this paper we propose the use of preferred outcome distributions as a new method to elicit individuals’ value and probability weighting functions in decisions under risk. Extant approaches for the elicitation of these two key ingredients of individuals’ risk attitude typically rely on a long, chained sequence of lottery choices. In contrast, preferred outcome distributions can be elicited through an intuitive graphical interface, and, as we show, the information contained in two preferred outcome distributions is sufficient to identify non-parametrically both the value function and the probability weighting function in rank-dependent utility models. To illustrate our method and its advantages, we run an incentive-compatible lab study in which participants use a simple graphical interface – the Distribution Builder (Goldstein et al. 2008) – to construct their preferred outcome distributions, subject to a budget constraint. Results show that estimates of the value function are in line with previous research but that probability weighting biases are diminished, thus favoring our proposed approach based on preferred outcome distributions
Using Preferred Outcome Distributions to estimate Value and Probability Weighting Functions in Decisions under Risk
In this paper we propose the use of preferred outcome distributions as a new method to elicit individuals' value and probability weighting functions in decisions under risk. Extant approaches for the elicitation of these two key ingredients of individuals' risk attitude typically rely on a long, chained sequence of lottery choices. In contrast, preferred outcome distributions can be elicited through an intuitive graphical interface, and, as we show, the information contained in two preferred outcome distributions is sufficient to identify non-parametrically both the value function and the probability weighting function in rank-dependent utility models. To illustrate our method and its advantages, we run an incentive-compatible lab study in which participants use a simple graphical interface - the Distribution Builder (Goldstein et al. 2008) - to construct their preferred outcome distributions, subject to a budget constraint. Results show that estimates of the value function are in line with previous research but that probability weighting biases are diminished, thus favoring our proposed approach based on preferred outcome distributions
Comparative study on composition of insect in close and open nursery of Federal College of Forestry Jos, Plateau State, Nigeria
Nursery being an area where young plants are raised before sowing or transplanting in gardens or field contains rich insect assemblages whose composition and abundance is under researched even in research institutes. Thus, the comparative study on the composition of insect in close and open nursery of Federal College of Forestry Jos, Plateau State, Nigeria was carried out in May 2015 in relation to the abundance and diversity of insect using pitfall trap and hand-picking sampling techniques. A total of 2,052 individuals distributed into 13 orders, 39 families, 50 genera and 55 species were collected. 1,557 (75.9%) individuals were collected from the open nursery (with: 13 orders, 39 families, 41 genera and 46 species) while, 495 (24.1%) individuals were found in the close nursery (with: 11 orders, 27 families, 38 genera and 47 species). Five individuals could not be identified beyond class and order levels. The distribution of insect taxa in descending order showed that Hymenoptera (62.8%), Coleoptera (11.1%) and Orthoptera (10.1%) are the most dominant, with Hymenoptera occurring the most in both sites. There was no significant difference (P > 0.05) in the pooled abundance of insect from both sampling techniques between the two nursery types. Although, insect abundance from pitfall trap collection between the two nursery types showed a significant difference (t= -2.494, df = 8, P = 0.03729) while, no significant difference (t= 1.0263, df = 8, P= 0.3348) for hand-picked insect between the two nursery types. To this end, this study shows that the nursery of Federal College of Forestry Jos is healthy due to the abundant and diverse insect species recorded in which the phytophagus individuals are the most dominant group, but are kept under check by the predaceous ones. The pitfall trap was a more efficient collection technique and should be used by insect collectors.Keywords: Close and open nursery, insect, pitfall trap, hand-pickin
Evaluation des moyens de lutte contre les simulies dans le cadre du programme OCP (Onchocerciasis Control Programme)
Le Programme de Lutte contre l'Onchocercose en Afrique de l'Ouest, pour contrôler le vecteur #S. damnosum s.l., utilise des larvicides qui sont essentiellement épandus par voie aérienne. Malgré la résistance plus ou moins réversible de certaines espèces du complexe #S. damnosum aux organophosphorés (téméphos et chlorphoxime), le Programme a réussi à trouver des insecticides de remplacement efficaces. Ces larvicides utilisés en alternance en tenant compte des débits des rivières, des espèces simulidiennes présentes, et de leur sensibilité aux divers insecticides, ont permis de maintenir les bons résultats acquis par le Programme. Par la seule lutte antivectorielle, l'OCP a réussi à contrôler la maladie sur plus de 90 % de l'aire initiale. Les terres fertiles qui étaient autrefois abandonnées du fait de l'onchocercose sont en voie de repeuplement et de nombreux projets de développement socio-économique sont en cours d'exécution. Les extensions effectuées vers l'Ouest et le Sud du Programme, et l'utilisation de l'ivermectine, un microfilaricide, permettront encore d'améliorer ces résultats. (Résumé d'auteur
Investigation of the Jahn-Teller Transition in TiF3 using Density Functional Theory
We use first principles density functional theory to calculate electronic and
magnetic properties of TiF3 using the full potential linearized augmented plane
wave method. The LDA approximation predicts a fully saturated ferromagnetic
metal and finds degenerate energy minima for high and low symmetry structures.
The experimentally observed Jahn-Teller phase transition at Tc=370K can not be
driven by the electron-phonon interaction alone, which is usually described
accurately by LDA.
Electron correlations beyond LDA are essential to lift the degeneracy of the
singly occupied Ti t2g orbital. Although the on-site Coulomb correlations are
important, the direction of the t2g-level splitting is determined by the
dipole-dipole interactions. The LDA+U functional predicts an aniferromagnetic
insulator with an orbitally ordered ground state. The input parameters U=8.1 eV
and J=0.9 eV for the Ti 3d orbital were found by varying the total charge on
the TiF ion using the molecular NRLMOL code. We estimate the
Heisenberg exchange constant for spin-1/2 on a cubic lattice to be
approximately 24 K. The symmetry lowering energy in LDA+U is about 900 K per
TiF3 formula unit.Comment: 7 pages, 9 figures, to appear in Phys. Rev.
What Attracts Men Who Batter to Their Partners? An Exploratory Study
Men who batter, because of particular personality traits and sense of entitlement,
may select partners whom they perceive will be dependent on them,
meet their emotional needs, or be “objects” of physical attractiveness. During
treatment intake, 181 offenders responded to the question, “What attracted
you to her (your partner)?” We explored whether men who mentioned their
own needs or her physical traits would engage in more frequent and severe
violence and would have specific forms of personality disorder dimensions or
personality traits. Six categories of attraction, including “her physical traits”
and “his needs,” were derived from the men’s responses. The results showed
that men who focused on their partners’ physical attractiveness were more
likely to be violent after treatment. Men who cited their own needs for their
attraction had higher scores on borderline personality, alcohol abuse, and
psychotic thinking and lower scores on compulsive-conformingPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/89970/1/Saunders-Kurko-Barlow-Crane 2011 What Attracts Men Who Batter to Their Partners JIV.pd
Obesidade, hipertensão arterial e suas influências sobre a massa e função do ventrículo esquerdo
In order to evaluate the influences of obesity and hypertension on left ventricular mass (LVM), we studied 121 women stratified into 4 groups: normotensive non-obeses (n = 25), hypertensive non-obeses (n = 30), normotensive obeses (n = 24) and hypertensive obeses (n = 42) according to their anthropometric and echocardiographic parameters and ambulatory blood pressure monitoring (ABPM). Hypertensive obeses showed higher LVM than the other groups - normotensive non-obeses, hypertensive non-obeses and normotensive obeses (167 ± 38.8 vs. 113 ± 26.4; vs. 133 ± 26.5; vs. 132 ± 29.2g; respectively, p < 0.05) ond higher diameter of left atrium (LA) as compared to the non-obese groups with or without hypertension (36 ± 4.3 vs. 33 ±5.1; vs. 35 ± 3.9mm; p < 0.05, respectively). Normotensive obese patients showed similar LVM to the hypertensive non-obeses (133 ± 26.5 vs. 132 ± 29.5g; NS) and increased LA as compared to the normotensive non-obeses (35 ± 3.9 vs. 31 ± 4.6mm; p < 0.05). A correlation between the waist circumference and waist-to-hip ratio with the blood pressure levels obtained by the ABPM, as well as between these measurements with the echocardiographic parameters, which reflect cardiac mass; body mass index only showed to be correlated to the LA diameter. The adjustment of LVM by the height instead of body surface resulted in an increase on the prevalence of LV hypertrophy among obese patients (10.6 vs. 36.7%, p < 0.01), but not among non-obeses. Lack of nocturnal blood pressure fall assessed by ABPM (non-dipper) was more prevalent among obese patients with or without hypertension; however, non-dipper hypertensive obese patients did not differ from the dippers according to the LVM. Our data demonstrate that obesity associated to hypertension provoke a more pronounced increase in LVM as compared to the condition separately. We also conclude that obese patients showed increased frequency of abnormal 24-hr blood pressure profile, characterized by decreased tensional drop during sleep.Para avaliar as influências da obesidade e da hipertensão sobre a massa de ventrículo esquerdo (MVE), estudamos 121 mulheres divididas em 4 grupos: não-obesas normotensas (n = 25), não-obesas hipertensas (n = 30), obesas normotensas (n = 24) e obesas hipertensas (n = 42) quanto a parâmetros antropométricos, ecocardiográficos e de monitorização ambulatorial da pressão arterial (MAPA). As pacientes obesas hipertensas apresentaram maior MVE que os outros grupos - não-obesas normotensas, não-obesas hipertensas e obesas normotensas (167 ± 38,8 vs. 113 + 26,4; vs. 133 ± 26,5; vs. 132 ± 29,2g; p < 0,05, respectivamente) e maior diâmetro de átrio esquerdo (AE) quando comparadas aos grupos de não-obesas, tanto normotensas como hipertensas (36 ± 4,3 vs. 33 ± 5,1; vs. 35 ± 3,9mm; p < 0,05, respectivamente). Obesas normotensas apresentaram MVE similar à do grupo não-obesas hipertensas (133 ± 26,5 vs. 132 ± 29,5g; NS) e aumento de AE quando comparadas às não-obesas normotensas (35 ± 3,9 vs. 31 ± 4,6mm; p < 0,05). Detectou-se correlação entre a circunferência da cintura e a razão cintura-quadril com os níveis pressóricos à MAPA, assim como entre estas medidas e parâmetros ecocardiográficos que avaliam a massa cardíaca; o índice de massa corporal só se correlacionou ao diâmetro do AE. A correção da MVE pela altura ao invés da superfície corpórea aumentou a prevalência de hipertrofia de VE nas obesas (10,6 vs. 36,7%, p < 0,01), mas não nas não-obesas. Ausência de descenso noturno da pressão arterial sistólica à MAPA (non-dipper) foi mais prevalente nas pacientes obesas, hipertensas ou não; entretanto, as obesas hipertensas non-dippers não diferiram das dippers quanto à MVE. Nossos dados demonstram que a obesidade associada à hipertensão aumenta a MVE de modo mais importante do que as condições isoladamente. Concluímos, ainda, que pacientes obesas também apresentam alta freqüência de alterações do ritmo da pressão arterial de 24 horas, caracterizada por menor queda pressórica durante o sono.Universidade Federal de São Paulo (UNIFESP) Departamento de Medicina Preventiva Departamento de MedicinaUNIFESP, Depto. de Medicina Preventiva Depto. de MedicinaSciEL
Microwave conductivity of a d-wave superconductor disordered by extended impurities: a real-space renormalization group approach
Using a real-space renormalization group (RSRG) technique, we compute the
microwave conductivity of a d-wave superconductor disordered by extended
impurities. To do this, we invoke a semiclassical approximation which naturally
accesses the Andreev bound states localized near each impurity. Tunneling
corrections (which are captured using the RSRG) lead to a delocalization of
these quasiparticles and an associated contribution to the microwave
conductivity.Comment: 8 pages, 4 figures. 2 figures added to previous versio
Numerical Study of Gluon Propagator and Confinement Scenario in Minimal Coulomb Gauge
We present numerical results in SU(2) lattice gauge theory for the
space-space and time-time components of the gluon propagator at equal time in
the minimal Coulomb gauge. It is found that the equal-time would-be physical
3-dimensionally transverse gluon propagator vanishes at
when extrapolated to infinite lattice volume, whereas the
instantaneous color-Coulomb potential is strongly enhanced at
. This has a natural interpretation in a confinement scenario in
which the would-be physical gluons leave the physical spectrum while the
long-range Coulomb force confines color. Gribov's formula provides an excellent fit to our data
for the 3-dimensionally transverse equal-time gluon propagator
for relevant values of .Comment: 23 pages, 12 figures, TeX file. Minor modifications, incorporating
referee's suggestion
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