5,696 research outputs found
Transmission in double quantum dots in the Kondo regime: Quantum-critical transitions and interference effects
We study the transmission through a double quantum-dot system in the Kondo
regime. An exact expression for the transmission coefficient in terms of fully
interacting many-body Green's functions is obtained. By mapping the system into
an effective Anderson impurity model, one can determine the transmission using
numerical renormalization-group methods. The transmission exhibits signatures
of the different Kondo regimes of the effective model, including an unusual
Kondo phase with split peaks in the spectral function, as well as a
pseudogapped regime exhibiting a quantum critical transition between Kondo and
unscreened phases.Comment: 4 pages, 3 figures; Submitted to Physica E (EP2DS-17 proceedings,
oral presentation), updated Ref
Interactions between landscape changes and host communities can regulate echinococcus multilocularis transmission
An area close to the Qinghai-Tibet plateau region and subject to intensive deforestation contains a large focus of human alveolar echinococcosis while sporadic human cases occur in the Doubs region of eastern France. The current review analyses and compares epidemiological and ecological results obtained in both regions. Analysis of rodent species assemblages within quantified rural landscapes in central China and eastern France shows a significant association between host species for the pathogenic helminth Echinococcus multilocularis, with prevalences of human alveolar echinococcosis and with land area under shrubland or grassland. This suggests that at the regional scale landscape can affect human disease distribution through interaction with small mammal communities and their population dynamics. Lidicker's ROMPA hypothesis helps to explain this association and provides a novel explanation of how landscape changes may result in increased risk of a rodent-borne zoonotic disease
Interaction between polar molecules subject to a far-off-resonant optical field: Entangled dipoles up- or down-holding each other
We show that the electric dipole-dipole interaction between a pair of polar
molecules undergoes an all-out transformation when superimposed by a far-off
resonant optical field. The combined interaction potential becomes tunable by
variation of wavelength, polarization and intensity of the optical field and
its dependence on the intermolecular separation exhibits a crossover from an
inverse-power to an oscillating behavior. The ability thereby offered to
control molecular interactions opens up avenues toward the creation and
manipulation of novel phases of ultracold polar gases among whose
characteristics is a long-range entanglement of the dipoles' mutual
orientation. We devised an accurate analytic model of such
optical-field-dressed dipole-dipole interaction potentials, which enables a
straightforward access to the optical-field parameters required for the design
of intermolecular interactions in the laboratory.Comment: 11 pages, 6 figures, 1 table. arXiv admin note: substantial text
overlap with arXiv:1104.104
Gradient test for generalised linear models with random effects.
This work develops the gradient test for parameter selection in generalised linear models with random effects. Asymptotically, the test statistic has a chi-squared distribution and the statistic has a compelling feature: it does not require computation of the Fisher information matrix. Performance of the test is verified through Monte Carlo simulations of size and power, and also compared to the likelihood ratio, Wald and Rao tests. The gradient test provides the best results overall when compared to the traditional tests, especially for smaller sample sizes
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Thunderstorm occurrence at ten sites across Great Britain over 1884–1993
The UK Met Office's Daily Weather Reports (DWR) contain extensive logs of UK thunderstorm activity. To date, only a very small fraction of these data have been digitized as part of the MIDAS dataset, and exclusively after 1950. Using the recently‐scanned UK Met Office Monthly Weather Reports (MWR), which are based on a subset of the observations that form the DWR, we here provide digitized data and a summary of thunderdays from 10 long‐running British stations over the period 1884–1993. The data are presented ‘as is’, with no attempt to provide any corrections or calibration. For 4 of the 10 stations, thunderday observations were discontinued at various times between 1949 and 1964, and it is necessary to switch to a neighbouring station in order to continue the series. Approximately half the series exhibit sharp drops in thunderdays at various points between 1960 and 1990, although none are coincident with known station changes. Comparison with nearby MIDAS stations suggests the low thunderdays are the result of changes in observing practice, rather than genuine changes in thunderstorm occurrence. These potential data issues limit interpretation of the long‐term trends. However, it can nevertheless be concluded that none of the stations show the expected increase in thunderdays as a result of the rise in surface temperature over the 20th century. In order to provide more quantitative determination of the long‐term trends in thunderstorm occurrence, we advocate further digitization efforts to recover the data from the numerous stations in the MWRs, and subsequent analysis of the common signals across neighbouring stations
Keep it simple: three indicators to deal with overfishing
Three simple fisheries indicators are presented: (i) percentage of mature fish in catch, with 100% as target; (ii) percent of specimens with optimum length in catch, with 100% as target; and (iii) percentage of ‘mega-spawners‘ in catch, with 0% as target, and 30–40% as representative of reasonable stock structure if no upper size limit exists. Application of these indicators to stocks of Gadus morhua, Sardinella aurita and Epinephelus aeneus demonstrate their usefulness. It is argued that such simple indicators have the potential to allow more stakeholders such as fishers, fish dealers, supermarket managers, consumers and politicians to participate in fisheries management and eventually hold and reverse the global pattern of convenience overfishing, which is defined here as deliberate overfishing sanctioned by official bodies who find it more convenient to risk eventual collapse of fish stocks than to risk social and political conflicts
Not fitting in and getting out : psychological type and congregational satisfaction among Anglican churchgoers in England
Listening to the motivations reported by individuals for ceasing church attendance and becoming church leavers, Francis and Richter identified high on the list the sense of "not fitting in". Drawing on psychological type theory, several recent studies have documented the way in which some psychological types are over-represented in church congregations and other psychological types are under-represented. Bringing these two observations together, the present study tested the hypothesis that church congregations have created type-alike communities within which individuals displaying the opposite type preferences are more likely to feel marginalised and to display lower levels of satisfaction with the congregations they attend. Data were provided by 1867 churchgoers who completed a measure of psychological type, together with measures of frequency of attendance and congregational satisfaction. These data confirmed that congregations were weighted towards preferences for introversion, sensing, feeling and judging, and that individuals displaying the opposite preferences (especially intuition, thinking and perceiving) recorded lower levels of congregational satisfaction. The implications of these findings are discussed for promoting congregational retention by enhancing awareness of psychological type preferences among those who attend
Modulation of emotional appraisal by false physiological feedback during fMRI
BACKGROUND
James and Lange proposed that emotions are the perception of physiological reactions. Two-level theories of emotion extend this model to suggest that cognitive interpretations of physiological changes shape self-reported emotions. Correspondingly false physiological feedback of evoked or tonic bodily responses can alter emotional attributions. Moreover, anxiety states are proposed to arise from detection of mismatch between actual and anticipated states of physiological arousal. However, the neural underpinnings of these phenomena previously have not been examined.
METHODOLOGY/PRINCIPAL FINDINGS
We undertook a functional brain imaging (fMRI) experiment to investigate how both primary and second-order levels of physiological (viscerosensory) representation impact on the processing of external emotional cues. 12 participants were scanned while judging face stimuli during both exercise and non-exercise conditions in the context of true and false auditory feedback of tonic heart rate. We observed that the perceived emotional intensity/salience of neutral faces was enhanced by false feedback of increased heart rate. Regional changes in neural activity corresponding to this behavioural interaction were observed within included right anterior insula, bilateral mid insula, and amygdala. In addition, right anterior insula activity was enhanced during by asynchronous relative to synchronous cardiac feedback even with no change in perceived or actual heart rate suggesting this region serves as a comparator to detect physiological mismatches. Finally, BOLD activity within right anterior insula and amygdala predicted the corresponding changes in perceived intensity ratings at both a group and an individual level.
CONCLUSIONS/SIGNIFICANCE
Our findings identify the neural substrates supporting behavioural effects of false physiological feedback, and highlight mechanisms that underlie subjective anxiety states, including the importance of the right anterior insula in guiding second-order "cognitive" representations of bodily arousal state
Differential scaling within an insect compound eye
Environmental and genetic influences cause individuals of a species to differ in size. As they do so, organ size and shape are scaled to available resources whilst maintaining function. The scaling of entire organs has been investigated extensively but scaling within organs remains poorly understood. By making use of the structure of the insect compound eye, we show that different regions of an organ can respond differentially to changes in body size. Wood ant (Formica rufa) compound eyes contain facets of different diameters in different regions. When the animal body size changes, lens diameters from different regions can increase or decrease in size either at the same rate (a ‘grade’ shift) or at different rates (a ‘slope’ shift). These options are not mutually exclusive, and we demonstrate that both types of scaling apply to different regions of the same eye. This demonstrates that different regions within a single organ can use different rules to govern their scaling, responding differently to their developmental environment. Thus, the control of scaling is more nuanced than previously appreciated, diverse responses occurring even among homologous cells within a single organ. Such fine control provides a rich substrate for the diversification of organ morphology
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