Effective interactions between inclusions in complex fluids driven out of equilibrium

The concept of fluctuation-induced effective interactions is extended to systems driven out of equilibrium. We compute the forces experienced by macroscopic objects immersed in a soft material driven by external shaking sources. We show that, in contrast with equilibrium Casimir forces induced by thermal fluctuations, their sign, range and amplitude depends on specifics of the shaking and can thus be tuned. We also comment upon the dispersion of these shaking-induced forces, and discuss their potential application to phase ordering in soft-materials.Comment: 10 pages, 8 figures, to appear in PR

Cognitive performance of healthy young rats following chronic donepezil administration.

RATIONALE: Experimental studies have investigated the effects of chronic donepezil treatment on the behavioral deficits elicited by reduced activity or the loss of cholinergic neurons that occurs in aging or in models of dementia. However, few studies have analyzed the effects of chronic donepezil treatment on the cognitive functions of intact animals. OBJECTIVES: The cognitive functions of healthy young rats treated chronically with the acetylcholinesterase inhibitor donepezil were evaluated using a wide behavioral test battery. RESULTS: Chronic treatment with donepezil ameliorated memory functions and explorative strategies, speeded up the acquisition of localizing knowledge, augmented responsiveness to the context, and reduced anxiety levels. However, it did not affect spatial span, modify motivational levels, or influence associative learning. CONCLUSIONS: The present findings show the specific profile of donepezil action on cognitive functions in the presence of unaltered cholinergic neurotransmission systems

Relativistic effects and primordial non-Gaussianity in the galaxy bias

When dealing with observables, one needs to generalize the bias relation between the observed galaxy fluctuation field to the underlying matter distribution in a gauge-invariant way. We provide such relation at second-order in perturbation theory adopting the local Eulerian bias model and starting from the observationally motivated uniform-redshift gauge. Our computation includes the presence of primordial non-Gaussianity. We show that large scale-dependent relativistic effects in the Eulerian bias arise independently from the presence of some primordial non-Gaussianity. Furthermore, the Eulerian bias inherits from the primordial non-Gaussianity not only a scale-dependence, but also a modulation with the angle of observation when sources with different biases are correlated.Comment: 12 pages, LaTeX file; version accepted for publication in JCA

A new approach to cosmological perturbations in f(R) models

We propose an analytic procedure that allows to determine quantitatively the deviation in the behavior of cosmological perturbations between a given f(R) modified gravity model and a LCDM reference model. Our method allows to study structure formation in these models from the largest scales, of the order of the Hubble horizon, down to scales deeply inside the Hubble radius, without employing the so-called "quasi-static" approximation. Although we restrict our analysis here to linear perturbations, our technique is completely general and can be extended to any perturbative order.Comment: 21 pages, 2 figures; Revised version according to reviewer's suggestions; Typos corrected; Added Reference

Te.M.P.O., an app for using temporal musical mismatch in post-stroke neurorehabilitation: a preliminary randomized controlled study

BACKGROUND: Recently, the potential rehabilitation value of music has been examined and music-based interventions and techniques such as the Negative Mismatch (MMN) have been increasingly investigated in the neurological rehabilitation context. OBJECTIVE: The aim of this study was to investigate the effectiveness of a negative mismatch-based therapy on the disability and quality of life in patients with stroke in sub-acute phase. METHODS: Thirty patients with a stroke diagnosis in sub-acute phase were randomly assigned to one of two groups: Mismatch (Mg) or Control (CTRLg) group. Both groups used an innovative Android application: Temporal Musical Patterns Organisation (Te.M.P.O). The Disability Rating Scale (DRS), the Modified Barthel Index (MBI) and the Stroke Specific Quality of Life scale (SSQoL) were used at the baseline (T0) and after four weeks of training (T1), in order to assess changes over time. RESULTS: Statistical analysis was performed using the data of 24 (Mg = 12, CTRLg = 12) subjects. The results show a major improvement of the Mg with respect to the CTRLg in all clinical scales score. CONCLUSION: The temporal negative mismatch-based therapy performed with the Te.M.P.O. application could be useful in improving the disability and the quality of life in stroke survivors in a sub-acute phase

Fluctuations of Fluctuation-Induced "Casimir" Forces

The force experienced by objects embedded in a correlated medium undergoing thermal fluctuations--the so-called fluctuation--induced force--is actually itself a fluctuating quantity. We compute the corresponding probability distribution and show that it is a Gaussian centered on the well-known Casimir force, with a non-universal standard deviation that can be typically as large as the mean force itself. The relevance of these results to the experimental measurement of fluctuation-induced forces is discussed, as well as the influence of the finite temporal resolution of the measuring apparatus.Comment: 4 pages, 2 figure

Cerebellar involvement in cognitive flexibility

The aim of the present study was to investigate whether the cerebellar structures are involved in functions requiring cognitive flexibility abilities. The flexibility of the hemicerebellectomized and control animals in learning a four-choice learning task, adapting to ever-changing response rules was investigated. While in the initial phase of the task both experimental groups exhibited similar performances, only the control animals significantly improved their performance as the sessions went by. The lack of improvement in lesioned animals' performance rendered their responses particularly defective in the final phases of the task, when conversely intact animals performed best, exploiting their "learning to learn" ability. The findings demonstrate the defective influence of the cerebellar lesion on the acquisition, not the execution, of new responses. The results underline the crucial role of the cerebellum in mediating cognitive flexibility behaviors

Cerebellar control of cortico-striatal LTD

Purpose: Recent anatomical studies showed the presence of cerebellar and basal ganglia connections. It is thus conceivable that the cerebellum may influence the striatal synaptic transmission in general, and synaptic plasticity in particular. Methods: In the present neurophysiological investigation in brain slices, we studied striatal long-term depression (LTD), a crucial form of synaptic plasticity involved in motor learning after cerebellar lesions in rats. Results: Striatal LTD was fully abolished in the left striatum of rats with right hemicerebellectomy recorded 3 and 7 days following surgery, when the motor deficits were at their peak. Fifteen days after the hemicerebellectomy, rats had partially compensated their motor deficits and high-frequency stimulation of excitatory synapses in the left striatum was able to induce a stable LTD. Striatal plasticity was conversely normal ipsilaterally to cerebellar lesions, as well as in the right and left striatum of sham-operated animals. Conclusions: These data show that the cerebellum controls striatal synaptic plasticity, supporting the notion that the two structures operate in conjunction during motor learning