Built-in reduction of statistical fluctuations of partitioning objects

Our theoretical and numerical investigation of the movement of an object that partitions a microtubule filled with small particles indicates that vibrations warranted by thermal equilibrium are reached only after a time that increases exponentially with the number of particles involved. This points to a basic mechanical process capable of breaching, on accessible time scales, the ultimate ergodic constraints that force randomness on bound microscale and nanoscale systems

Polarization and energy dynamics in ultrafocused optical Kerr propagation

Developing a complete vectorial description of optical nonparaxial propagation of highly focused beams in Kerr media, we disclose a family of new phenomena. These phenomena appear to emerge as a consequence of the mutual coupling of all three components of the optical field. This circumstance, which is intrinsic to the very nature of Kerr propagation, was previously discarded on the basis of the conjecture that a reduced system is possible in which only one transverse field component interacts with the longitudinal component

Postmenopausal bone loss : prevention and replacement

Osteoporosis is a skeletal disorder predominantly affecting postmenopausal women. Combination therapy of Carbocalcitonin (Elcatonin) and oral conjugated oestrogens (Premarin) not only prevents postmenopausal bone loss but leads to an increase in bone mass in normal early postmenopausal women. The aims of the study was to investigate the effect of combination therapy. A combination of Elcatonin (Carbo calcitonin) and Premarin was compared to Premarin alone, and to Elcatonin (Carbocalcitonin) alone and all groups were then compared to a control group.peer-reviewe

Maximum fractional energy transmissible over a linear dispersive medium

We investigate the problem of transmitting the maximum fractional energy over a given length of a linear dispersive medium (e.g., a single-mode optical fiber) once the input pulse duration and the output detection time are assigned

Self-focusing and self-trapping in unbiased centrosymmetric photorefractive media

We predict self-focusing and self-trapping of optical beams propagating in unbiased centrosymmetric photorefractive crystals in the near-transition paraelectric phase, where the nonlinear response is proportional to the square of the diffusion space-charge field

Collision and fusion of counterpropagating micron-sized optical beams in non-uniformly biased photorefractive crystals

We theoretically investigate collision of optical beams travelling in opposite directions through a centrosymmetric photorefractive crystal biased by a spatially non-uniform voltage. We analytically predict the fusion of counterpropagating solitons in conditions in which the applied voltage is rapidly modulated along the propagation axis, so that self-bending is suppressed by the "restoring symmetry" mechanism. Moreover, when the applied voltage is slowly modulated, we predict that the modified self-bending allows conditions in which the two beams fuse together, forming a curved light-channel splice.Comment: 12 page

Ultra-deep imaging of turbid samples by enhanced photon harvesting

We constructed an advanced detection system for two-photon fluorescence microscopy that allows us to image in biological tissue and tissue phantoms up to the depth of a few mm with micron resolution. The innovation lies in the detection system which is much more sensitive to low level fluorescence signals than the fluorescence detection configuration used in conventional two-photon fluorescence microscopes. A wide area photocathode photomultiplier tube (PMT) was used to detect fluorescence photons directly from a wide (1 inch diameter) area of the turbid sample, as opposed to the photon collection by the microscope objective which can only collect light from a relatively small area of the sample. The optical path between the sample and the photocathode is refractive index matched to curtail losses at the boundaries due to reflections. The system has been successfully employed in the imaging of tissue phantoms simulating brain optical properties and in biological tissues, such as murine small intestine, colon, tumors, and other samples. The system has in-depth fluorescence lifetime imaging (FLIM) capabilities and is also highly suitable for SHG signal detection, such as collagen fibers and muscles, due to the intrinsically forward-directed propagation of SHG photons. © 2013 SPIE

Intrinsic irreversibility of Markovian chains

We show that for a large class of stationary Markov processes the total variation distance between the final equilibrium distribution and that at a given time is a strongly monotonic vanishing function. We illustrate this for basic paradigmatic processes and discuss how, for systems susceptible to a canonical description, this can be interpreted as a statistical arrow of time that exists besides the standard decrease of free energy

267 Occupation and Multiple Sclerosis: an Italian case-control study

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