767 research outputs found
Singlet-triplet transitions in highly correlated nanowire quantum dots
We consider a quantum dot embedded in a three-dimensional nanowire with
tunable aspect ratio a. A configuration interaction theory is developed to
calculate the energy spectra of the finite 1D quantum dot systems charged with
two electrons in the presence of magnetic fields B along the wire axis.
Fruitful singlet-triplet transition behaviors are revealed and explained in
terms of the competing exchange interaction, correlation interaction, and spin
Zeeman energy. In the high aspect ratio regime, the singlet-triplet transitions
are shown designable by tuning the parameters a and B. The transitions also
manifest the highly correlated nature of long nanowire quantum dots.Comment: 4 pages, 4 figure
Apparent negative motion of vortex matter due to inhomogeneous pinning
We investigate the transport of vortices in superconductors with inhomgeneous pinning under a driving force. The inhomogeneity of pinning is simplified as strong-weak pinning regions. It is demonstrated that the interactions between the vortices captured by strong pinning potentials and the vortices in the weak pinning region cause absolute negative motion (ANM) of vortices: The vortices which are climbing toward the high barriers induced by the strong pinning with the help of driving force move toward the opposite direction of the force and back to their equilibrium positions in the weak pinning region as the force decreases or is withdrawn. Our simulations reveal that the hysteresis of ANM is determined by the competition between the speed of the negative motion which depends on the piining inhomogeneity in superconductors and the speed of the driving force. Under the conditions of either larger force scanning rate or higher pinning inhomogeneity, a marked ANM and a larger hysteretic speed-force loop could be observed. This indicates that the time window to observe the ANM should be chosen properly. Moreover, the V-1 characteristics of Ag-sheathed Bi=2223 tapes are measured, and experimental observations are qualitatively in agreement with the simulation
The effects of mindfulness-based stress reduction program on the mental health of family caregivers: a randomized controlled trial
<b>Background</b> Caregivers of people with chronic conditions are more likely than non-caregivers to have depression and emotional problems. Few studies have examined the effectiveness of mindfulness-based stress reduction (MBSR) in improving their mental well-being. <p></p>
<b>Methods</b> Caregivers of persons with chronic conditions who scored 7 or above in the Caregiver Strain Index were randomly assigned to the 8-week MBSR group (n = 70) or the self-help control group (n = 71). Validated instruments were used to assess the changes in depressive and anxiety symptoms, quality of life, self-efficacy, self-compassion and mindfulness. Assessments were conducted at baseline, post-intervention and at the 3-month follow-up. <p></p>
<b>Results </b>Compared to the participants in the control group, participants in the MBSR group had a significantly greater decrease in depressive symptoms at post-intervention and at 3 months post-intervention (p < 0.01). The improvement in state anxiety symptoms was significantly greater among participants in the MBSR group than those of the control group at post-intervention (p = 0.007), although this difference was not statistically significant at 3 months post-intervention (p = 0.084). There was also a statistically significant larger increase in self-efficacy (controlling negative thoughts; p = 0.041) and mindfulness (p = 0.001) among participants in the MBSR group at the 3-month follow-up compared to the participants in the control group. No statistically significant group effects (MBSR vs. control) were found in perceived stress, quality of life or self-compassion. <p></p>
<b>Conclusions </b>MBSR appears to be a feasible and acceptable intervention to improve mental health among family caregivers with significant care burden, although further studies that include an active control group are needed to make the findings more conclusive
Anterior Hippocampus and Goal-Directed Spatial Decision Making
Contains fulltext :
115487.pdf (publisher's version ) (Open Access
Onsager Relations and Hydrodynamic Balance Equations in 2D Quantum Wells
In this letter we clarify the role of heat flux in the hydrodynamic balance
equations in 2D quantum wells, facilitating the formulation of an Onsager
relation within the framework of this theory. We find that the Onsager relation
is satisfied within the framework of the 2D hydrodynamic balance equation
transport theory at sufficiently high density. The condition of high density is
consonant with the requirement of strong electron-electron interactions for the
validity of our balance equation formulation.Comment: 11 pages, RevTex, 4 postscript figures are avaliable upon reques
Parental Influence on Child and Adolescent Physical Activity Level: A Meta-Analysis
Parents are often regarded as one of the significant social agents who are important to the participation of physical activity (PA) among children and adolescents. However, within the literature, the relationships between parental influences and child and adolescent PA have been inconclusive and discordant. The purpose of this meta-analysis was to quantify and synthesize the associations between parental social influences (positive parental influence, punishment, and discouragement) and the PA level of children and adolescents. Through a systematic literature search using PsycINFO, Web of Science, PubMed, ProQuest, and SPORTDiscus databases, we identified 112 eligible studies and subsequently extracted 741 effect sizes for our analysis. Multilevel meta-analysis showed that the corrected zero-order correlation of positive parental influence was positive and statistically significant, r = 0.202, SE = 0.014, t = 14.975, p \u3c 0.001, 95% confidence interval (CI) = [0.176, 0.228]. Further moderation analysis also found that this was significantly moderated by parental gender (maternal vs. paternal), respondent of influence measure (parent-reported vs. child-reported), and type of PA measure (subjective vs. objective). The corrected zero-order correlations of negative parental influences (i.e., punishment and discouragement) were not statistically significant, and no significant moderation effects were observed. The findings of our meta-analysis showed that children and adolescents had higher PA levels when their parents supported PA participation by exerting positive social influence. Punishment and discouragement against PA by parents did not appear to be significantly associated with the PA level of children and adolescents. The findings of negative parental social influence were mixed and required further investigations
Effect of dietary organic zinc sources on growth performance, incidence of diarrhoea, serum and tissue zinc concentrations, and intestinal morphology in growing rabbits
[EN] This study was conducted to evaluate the effect of dietary organic zinc (Zn) sources on growth performance, the incidence of diarrhoea, serum and tissue Zn concentration, and intestinal morphology in growing rabbits. A total of 120 New Zealand White rabbits aged 35 d and with an initial body weight of 755±15 g, were randomly divided into 4 treatment groups for a 49 d feeding trial. Dietary treatments were designed with different Zn supplements as follows: (1) Control group: 80 mg/kg Zn as ZnSO4; (2) ZnLA group: 80 mg/kg Zn as Zn lactate; (3) ZnMet group: 80 mg/kg Zn as Zn methionine; (4) ZnGly group: 80 mg/kg Zn as Zn glycine. The results showed that, when compared with rabbits fed ZnSO4, supplementation with ZnLA improved (P4. Supplementing with ZnLA increased duodenum villi height (681.63 vs. 587.14 μm, P4, except that feeding ZnMet led to higher (P4. The results indicated that supplementation with 80 mg/kg Zn as ZnLA could improve growth performance, increase liver Zn concentration and enhance duodenum morphology, while reducing the incidence of diarrhoea in growing rabbits.Yan, J.; Zhang, G.; Zhang, C.; Tang, L.; Kuang, S. (2017). Effect of dietary organic zinc sources on growth performance, incidence of diarrhoea, serum and tissue zinc concentrations, and intestinal morphology in growing rabbits. World Rabbit Science. 25(1):43-49. doi:10.4995/wrs.2017.5770.SWORD434925
CPR Coding Manual
"The fourth activity we have undertaken has been the identification of in-depth case studies that describe how CPR appropriators have succeeded or failed in efforts to manage inshore fisheries, small- to medium-sized irrigation systems, communal forests, or grazing lands. Identifying and coding in-depth case studies is undertaken in several steps. Most of this manual is devoted to an in-depth discussion of this activity.
Substantial uptake of atmospheric and groundwater nitrogen by dune slacks under different water table regimes
Dune slacks are biodiverse seasonal wetlands which experience considerable fluctuations in water table depths. They are subject to multiple threats such as eutrophication and climate change, and the interactions of both of these pressures are poorly understood. In this study we measured the impact of groundwater nitrogen contamination, as ammonium nitrate (0, 0.2, 10 mg/L of DIN, dissolved inorganic nitrogen), lowered water table depth (lowered by 10 cm) and the interactions of these factors, in a mesocosm study. We measured gross nutrient budgets, evapotranspiration rates, the growth of individual species and plant tissue chemistry. This study found that nitrogen uptake within dune slack habitats is substantial. Atmospheric inputs of 23 kg N ha−1 yr.−1 were retained by the mesocosms, with no increase of nutrient levels in the groundwater, i.e. there was no leaching of excess N. When N was added to the groundwater (in addition to atmospheric N), total uptake was equivalent to 116 kg N ha−1 yr.−1, at a groundwater DIN concentration of 10 mg/L. This resulted in increased plant tissue N concentrations showing uptake by the vegetation. The effect of lowering water tables did not influence N uptake, but did alter vegetation composition. This suggests that groundwater can be a substantial input of N to these habitats and should be considered in combination with atmospheric inputs, when assessing potential ecosystem damage
Statistical mechanics of RNA folding: importance of alphabet size
We construct a minimalist model of RNA secondary-structure formation and use
it to study the mapping from sequence to structure. There are strong,
qualitative differences between two-letter and four or six-letter alphabets.
With only two kinds of bases, there are many alternate folding configurations,
yielding thermodynamically stable ground-states only for a small set of
structures of high designability, i.e., total number of associated sequences.
In contrast, sequences made from four bases, as found in nature, or six bases
have far fewer competing folding configurations, resulting in a much greater
average stability of the ground state.Comment: 7 figures; uses revtex
- …