Quantum versus Semiclassical Description of Selftrapping: Anharmonic Effects

Selftrapping has been traditionally studied on the assumption that quasiparticles interact with harmonic phonons and that this interaction is linear in the displacement of the phonon. To complement recent semiclassical studies of anharmonicity and nonlinearity in this context, we present below a fully quantum mechanical analysis of a two-site system, where the oscillator is described by a tunably anharmonic potential, with a square well with infinite walls and the harmonic potential as its extreme limits, and wherein the interaction is nonlinear in the oscillator displacement. We find that even highly anharmonic polarons behave similar to their harmonic counterparts in that selftrapping is preserved for long times in the limit of strong coupling, and that the polaronic tunneling time scale depends exponentially on the polaron binding energy. Further, in agreement, with earlier results related to harmonic polarons, the semiclassical approximation agrees with the full quantum result in the massive oscillator limit of small oscillator frequency and strong quasiparticle-oscillator coupling.Comment: 10 pages, 6 figures, to appear in Phys. Rev.

Spin and Conductance-Peak-Spacing Distributions in Large Quantum Dots: A Density Functional Theory Study

We use spin-density-functional theory to study the spacing between conductance peaks and the ground-state spin of 2D model quantum dots with up to 200 electrons. Distributions for different ranges of electron number are obtained in both symmetric and asymmetric potentials. The even/odd effect is pronounced for small symmetric dots but vanishes for large asymmetric ones, suggesting substantially stronger interaction effects than expected. The fraction of high-spin ground states is remarkably large.Comment: 4 pages, 3 figure

Exploring the Healthy Eye Microbiota Niche in a Multicenter Study

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Identification of a Brainstem Circuit Regulating Visual Cortical State in Parallel with Locomotion

SummarySensory processing is dependent upon behavioral state. In mice, locomotion is accompanied by changes in cortical state and enhanced visual responses. Although recent studies have begun to elucidate intrinsic cortical mechanisms underlying this effect, the neural circuits that initially couple locomotion to cortical processing are unknown. The mesencephalic locomotor region (MLR) has been shown to be capable of initiating running and is associated with the ascending reticular activating system. Here, we find that optogenetic stimulation of the MLR in awake, head-fixed mice can induce both locomotion and increases in the gain of cortical responses. MLR stimulation below the threshold for overt movement similarly changed cortical processing, revealing that MLR’s effects on cortex are dissociable from locomotion. Likewise, stimulation of MLR projections to the basal forebrain also enhanced cortical responses, suggesting a pathway linking the MLR to cortex. These studies demonstrate that the MLR regulates cortical state in parallel with locomotion

Development of Feline Immunodeficiency Virus ORF-A (tat) Mutants: In Vitro and in Vivo Characterization

AbstractA functional ORF-A is essential for efficient feline immunodeficiency virus replication in lymphocytes. We have characterized a series of mutants of the Petaluma strain, derived from p34TF10 and having different combinations of stop codons and increasingly long deletions in ORF-A. Six clones proved fully replicative in fibroblastoid Crandell feline kidney cells and monocyte-derived macrophage cultures but failed to replicate in T cell lines and primary lymphoblasts. Cats inoculated with three selected mutants had considerably milder infections than controls given intact ORF-A virus. In vivo, the mutants maintained growth properties similar to those in vitro for at least 7 months, except that replication in lymphoid cells was strongly reduced but not ablated. One mutant underwent extensive ORF-A changes without, however, reverting to wild-type. Antiviral immune responses were feeble in all cats, suggesting that viral loads were too low to represent a sufficiently powerful antigenic stimulus

A lentiviral vector with a short troponin-I promoter for tracking cardiomyocyte differentiation of human embryonic stem cells

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Optogenetic Modulation of Neural Circuits that Underlie Reward Seeking

The manifestation of complex neuropsychiatric disorders such as drug and alcohol addiction is thought to result from progressive maladaptive alterations in neural circuit function. Clearly, repeated drug exposure alters a distributed network of neural circuit elements. However, a more precise understanding of addiction has been hampered by an inability to control and, consequently, identify specific circuit components that underlie addictive behaviors. The development of optogenetic strategies for selectively modulating the activity of genetically defined neuronal populations has provided a means for determining the relationship between circuit function and behavior with a level of precision that has been previously unobtainable. Here, we briefly review the main optogenetic studies that have contributed to elucidate neural circuit connectivity within the ventral tegmental area and the nucleus accumbens, two brain nuclei that are essential for the manifestation of addiction-related behaviors. Additional targeted manipulation of genetically defined neural populations in these brain regions as well as afferent and efferent structures promises to delineate the cellular mechanisms and circuit components required for the transition from natural goal-directed behavior to compulsive reward-seeking despite negative consequences

Active crustal extension and strain accumulation from GPS data in the Molise region (central-southern Apennines, Italy)

In this paper, we report new GPS measurements which indicate active NE-SW extension and strain accumulation in the Molise region (Apennines, Italy). The GPS observations were collected during campaigns on benchmarks of the dense IGM95 network (average distance 20 km), spanning a maximum observation interval of 13 years, and have been integrated with measurements from the available permanent GPS sites. Considering the differential motion of the GPS sites, located on the Tyrrhenian and Adriatic coasts, we can evaluate a 4-5 mm/yr extension accommodated across this part of the Apennines. The velocity field exhibits clusters of sites with homogeneous velocity vectors, outlining two main divergence areas, both characterized by the largest velocity gradients: one near Venafro and the other near Isernia where two primary active faults and several historical earthquakes have been documented. These results suggest that an active extension in this part of the Apennines can be currently distributed between the two faults systems associated with the largest earthquakes of this region

Longitudinal study of Salmonella infection in four Italian farrow-to finish swine herds

A longitudinal study of Salmonella enterica infection was carried out in 4 Italian farrow-to-finish swine herds. In each herd 5 litters were randomly selected and in each litter 6 piglets ear tagged. Thus, on each farm 30 pigs were included in the study. Individual blood samples were collected for serologic examination at weaning from all piglets and in the same day from all sows 1n the farrowing unit. Piglets were bled again at approximately 60, 90, 150, 210 and 270 days of life with the last blood sample collected at slaughtering. In one herd, in which the duration of productive cycle was about 12 months, the last blood samples was collected at 350 days of life. 5 pen pooled faecal samples were collected from each herd for bacteriological examination with the same time schedule of blood samples. At slaughtering mesenteric lymph nodes were collected from each ear tagged pig. Sera-prevalence (cutoff S/P ratio 0,25) in sows varied from 93,8% to 100%. In all herds sera-prevalence in piglets showed a similar profile with complete decline of maternal antibodies at day 60 and clear sera-conversion between day 90 and day 150. The peak of sera-prevalence was observed between day 210 and day 270. Sera-prevalence at slaughtering varied from 66% to 100%. Salmonella was isolated from faecal samples in 3 out of 4 herds. No Salmonella was isolated from mesenteric lymph nodes at slaughter in 2 herds. Culture prevalence from mesenteric lymph nodes in the other herds was respectively 3,3% and 30%. This longitudinal study provides original information about epidemiological dynamics of Salmonella enterica infection in Italian swine herds in consideration of the typical longer fattening cycles

The scotogenic contact lens: a novel device for treating binocular diplopia

Binocular diplopia is a debilitating visual symptom requiring immediate intervention for symptomatic control, whether or not definitive treatment is eventually possible. Where prismatic correction is infeasible, the current standard is occlusion, either by a patch or an opaque contact lens. In eliminating one problem-diplopia-occlusive techniques invariably create another: reduced peripheral vision. Crucially, this is often unnecessary, for the reduced spatial resolution in the periphery limits its contribution to the perception of diplopia. Here, we therefore introduce a novel soft contact lens device that instead creates a monocular central scotoma inversely mirroring the physiological variation in spatial acuity across the monocular visual field, thereby suppressing the diplopia with minimal impact on the periphery. We compared the device against standard eye patching in 12 normal subjects with prism-induced binocular diplopia and 12 patients with binocular diplopia of diverse causes. Indexed by self-reported scores and binocular perimetry, the scotogenic contact lens was comparably effective in eliminating the diplopia while significantly superior in acceptability and its impact on the peripheral visual field. This simple, inexpensive, non-invasive device may thus be an effective new tool in the treatment of a familiar but still troublesome clinical problem