14,693 research outputs found
Double dynamical regime of confined water
The Van Hove self correlation function of water confined in a silica pore is
calculated from Molecular Dynamics trajectories upon supercooling. At long time
in the relaxation region we found that the behaviour of the real space
time dependent correlators can be decomposed in a very slow, almost frozen,
dynamics due to the bound water close to the substrate and a faster dynamics of
the free water which resides far from the confining surface. For free water we
confirm the evidences of an approach to a crossover mode coupling transition,
previously found in Q space. In the short time region we found that the two
dynamical regimes are overimposed and cannot be distinguished. This shows that
the interplay between the slower and the faster dynamics emerges in going from
early times to the relaxation region, where a layer analysis of the
dynamical properties can be performed.Comment: 6 pages with 9 figures. RevTeX. Accepted for pulbication in J. Phys.
Cond. Mat
A multidimensional spatial lag panel data model with spatial moving average nested random effects errors
This paper focuses on a three-dimensional model that combines two different
types of spatial interaction effects, i.e. endogenous interaction effects via a spatial
lag on the dependent variable and interaction effects among the disturbances via a
spatial moving average (SMA) nested random effects errors. A three-stage procedure
is proposed to estimate the parameters. In a first stage, the spatial lag panel data model
is estimated using an instrumental variable (IV) estimator. In a second stage, a generalized
moments (GM) approach is developed to estimate the SMA parameter and the
variance components of the disturbance process using IV residuals from the first stage.
In a third stage, to purge the equation of the specific structure of the disturbances a
Cochrane–Orcutt-type transformation is applied combined with the IV principle. This
leads to the GM spatial IV estimator and the regression parameter estimates. Monte
Carlo simulations show that our estimators are not very different in terms of root mean
square error from those produced by maximum likelihood. The approach is applied to
European Union regional employment data for regions nested within countries
Scale-invariant magnetoresistance in a cuprate superconductor
The anomalous metallic state in high-temperature superconducting cuprates is
masked by the onset of superconductivity near a quantum critical point. Use of
high magnetic fields to suppress superconductivity has enabled a detailed study
of the ground state in these systems. Yet, the direct effect of strong magnetic
fields on the metallic behavior at low temperatures is poorly understood,
especially near critical doping, . Here we report a high-field
magnetoresistance study of thin films of \LSCO cuprates in close vicinity to
critical doping, . We find that the metallic state
exposed by suppressing superconductivity is characterized by a
magnetoresistance that is linear in magnetic field up to the highest measured
fields of T. The slope of the linear-in-field resistivity is
temperature-independent at very high fields. It mirrors the magnitude and
doping evolution of the linear-in-temperature resistivity that has been
ascribed to Planckian dissipation near a quantum critical point. This
establishes true scale-invariant conductivity as the signature of the strange
metal state in the high-temperature superconducting cuprates.Comment: 10 pages, 3 figure
Ultraviolet writing of channel waveguides in proton-exchanged LiNbO<sub>3</sub>
We report on a direct ultraviolet (UV) writing method for the fabrication of channel waveguides at 1.55 µm in LiNbO3 through UV irradiation of surface and buried planar waveguides made by annealed proton exchange and reverse proton exchange. A systematic study of the guidance properties as a function of the UV writing conditions is presented
Macrophage TNF-α mediates parathion-induced airway hyperreactivity in guinea pigs.
Organophosphorus pesticides (OPs) are implicated in human asthma. We previously demonstrated that, at concentrations that do not inhibit acetylcholinesterase activity, the OP parathion causes airway hyperreactivity in guinea pigs as a result of functional loss of inhibitory M2 muscarinic receptors on parasympathetic nerves. Because macrophages are associated with asthma, we investigated whether macrophages mediate parathion-induced M2 receptor dysfunction and airway hyperreactivity. Airway physiology was measured in guinea pigs 24 h after a subcutaneous injection of parathion. Pretreatment with liposome-encapsulated clodronate induced alveolar macrophage apoptosis and prevented parathion-induced airway hyperreactivity in response to electrical stimulation of the vagus nerves. As determined by qPCR, TNF-α and IL-1β mRNA levels were increased in alveolar macrophages isolated from parathion-treated guinea pigs. Parathion treatment of alveolar macrophages ex vivo did not significantly increase IL-1β and TNF-α mRNA but did significantly increase TNF-α protein release. Consistent with these data, pretreatment with the TNF-α inhibitor etanercept but not the IL-1β receptor inhibitor anakinra prevented parathion-induced airway hyperreactivity and protected M2 receptor function. These data suggest a novel mechanism of OP-induced airway hyperreactivity in which low-level parathion activates macrophages to release TNF-α-causing M2 receptor dysfunction and airway hyperreactivity. These observations have important implications regarding therapeutic approaches for treating respiratory disease associated with OP exposures
Is local best? Examining the evidence for local adaptation in trees and its scale
Although the importance of using local provenance planting stock for woodland production, habitat conservation and restoration remains contentious, the concept is easy to understand, attractive and easy to ‘sell’. With limited information about the extent and scale of adaptive variation in native trees, discussion about suitable seed sources often emphasises “local” in a very narrow sense or within political boundaries, rather than being based on sound evidence of the scale over which adaptation occurs. Concerns exist over the actual scale (magnitude and spatial scale) of adaptation in trees and the relative dangers of incorrect seed source or restricted seed collection, leading to the establishment of trees with restricted genetic diversity and limited adaptive potential. Tree provenance and progeny field trials in many parts of the world have shown the existence of genotype by environment interaction in many tree species, but have not necessarily looked at whether this is expressed as a home site advantage (i.e. whether provenance performance is unstable across sites, and there is better performance of a local seed source). This review will examine the evidence for local adaptation and its scale in a number of native tree species from different trial sites across the globe (e.g. tropical, Mediterranean, temperate). These trials have been measured and in some cases results published in a range of formats. The data have, however, usually been presented in the form of which provenances grow best at which sites. The review will examine existing data (published and unpublished) in the context of the scale of local adaptation, with the results being presented in two formats: (a) relating survival, performance of provenances (classified by seed zone/provenance region of origin) to seed zone/provenance region of the planting site; (b) plotting survival, performance provenances against the distance (Euclidean/ecological) between the provenance and the trial site
Residents\u27 Confidence Providing Primary Care With Behavioral Health Integration
BACKGROUND AND OBJECTIVES: Behavioral health integration (BHI) entails integrated behavioral health clinicians (IBHCs) providing care-generally for mental health and substance abuse disorders and behavioral comorbidity- within the operational functioning of primary care. Because limited data exist regarding BHI in residency, we studied its impact on resident education by examining whether increased behavioral health (BH) co-management improved residents\u27 perceived ability to treat BH conditions.
METHODS: We included residents from internal and family medicine training programs using BHI in residents\u27 continuity clinics and assessed the level of co-management between primary care and IBHCs and the following domains: (1) confidence in managing BH conditions, (2) barriers to BH provision, (3) perception of autonomy when working with IBHCs, (4) satisfaction with the clinic, and (5) perceived educational value of BH learning modes.
RESULTS: Altogether, 117 residents participated in our survey (73.1% response rate). Residents who had co-managed \u3e /= five patients alongside IBHCs reported significantly higher confidence than those who had co-managed andlt; five patients with BH conditions. The association remained significant after adjustment for residents\u27 level of training and specialty. In rating BH learning modes, residents rated most highly active collaboration with IBHCs and observation with feedback from clinic preceptors.
CONCLUSIONS: BHI training within residency enhances perceived learning and confidence in providing BH care
Relationships Among Metabolic-Risk, Body Fatness, and Muscular Fitness in Young Obese Latino Children
International Journal of Exercise Science 13(3): 488-500, 2020. Given the high prevalence of obesity in Latino children and potential health risks, the purpose of this study was to: 1) evaluate relationships among metabolic-risk, fitness, and body fatness; 2) determine sex differences in cardio-metabolic risk factors and fitness of obese children of Latino descent. Sixty children (boys, n= 39, 7.8 ± 1.5 years; girls, n= 21, 7.2 ± 1.5 years; body mass index, 97.8 ± 2.5thpercentile) completed assessments of height, weight, and body fat, prior to fasted blood draws and a battery of fitness tests. Cardio-metabolic markers were analyzed, and a metabolic risk score created. Correlations and regression analyses evaluated the relationships among body fatness, metabolic-risk, and fitness. Independent samples t-tests determined sex differences (p \u3c 0.05). Body fat related negatively to lower body power (p \u3c 0.016), but positively to upper body power (p= 0.049). After controlling for age and sex, body fat (p\u3c 0.001) was a positive predictor of variance in metabolic-risk scores, (R2 = 0.39, p \u3c 0.001). Further, the association between body fat and metabolic-risk was not moderated by sex. Metabolic-risk scores and body fat were similar for both sexes, but boys performed better on muscular fitness tests, even after accounting for fat free mass (p \u3c 0.05). Higher body fatness in obese Latino children may result in greater metabolic-risk and difficulty performing weight-bearing tasks. Therefore, culturally adapted weight management programs should employ a multifaceted approach to improve metabolic-risk and fitness
Microclimate in coffee plantation grown under grevillea trees shading.
Microclima de café arborizado com grevílea. Medições de radiação solar global, velocidade do vento, temperatura e umidade relativa do ar, foram realizadas em um cafezal (Coffea arabica L.) cv. Icatu Vermelho IAC 4045, cultivado a pleno sol e arborizado com grevílea (Grevillea robusta), no município de Mococa ? SP (21º 28? S, 47º 01? W, altitude 665 m) entre janeiro e dezembro de 2005, com o objetivo de apresentar os efeitos do cultivo arborizado no microclima. Os resultados obtidos mostraram que houve atenuação média dos valores de radiação solar global, em cultivo de café arborizado, em 26%, com variação mensal de 24 a 30%. Pela descontinuidade da cobertura das árvores de grevílea, foi verificada diferença de transmissão da radiação solar em diferentes pontos do sistema arborizado. Foi verificada ainda redução média de 35% nas médias quinquidiais da velocidade do vento no cultivo arborizado em relação ao cultivo a pleno sol. O cultivo arborizado promoveu redução na temperatura máxima do ar e no déficit de saturação de vapor no período diurno, sendo essas reduções mais evidentes no ponto amostral próximo à árvore de grevílea
The Intrinsically X-ray Weak Quasar PHL 1811. I. X-ray Observations and Spectral Energy Distribution
This is the first of two papers reporting observations and analysis of the
unusually bright (m_b=14.4), luminous (M_B=-25.5), nearby (z=0.192) narrow-line
quasar PHL 1811, focusing on the X-ray properties and the spectral energy
distribution. Two Chandra observations reveal a weak X-ray source with a steep
spectrum. Variability by a factor of 4 between the two observations separated
by 12 days suggest that the X-rays are not scattered emission. The XMM-Newton
spectra are modelled in the 0.3--5 keV band by a steep power law with \Gamma =
2.3\pm 0.1, and the upper limit on intrinsic absorption is 8.7 x 10^{20}
cm^{-2}. The spectral slopes are consistent with power law indices commonly
observed in NLS1s, and it appears that we observe the central engine X-rays
directly. Including two recent Swift ToO snapshots, a factor of ~5 variability
was observed among the five X-ray observations reported here. In contrast, the
UV photometry obtained by the XMM-Newton OM and Swift UVOT, and the HST
spectrum reveal no significant UV variability. The \alpha_{ox} inferred from
the Chandra and contemporaneous HST spectrum is -2.3 \pm 0.1, significantly
steeper than observed from other quasars of the same optical luminosity. The
steep, canonical X-ray spectra, lack of absorption, and significant X-ray
variability lead us to conclude that PHL 1811 is intrinsically X-ray weak. We
also discuss an accretion disk model, and the host galaxy of PHL 1811.Comment: 45 pages, 9 figures, accepted for publication in Ap
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