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We analyze the transport properties of a Brownian particle diffusing along a two-dimensional septate channel, namely, a channel formed by equal rectangular cavities separated by narrow pores, subjected to an external longitudinal drive. We determine analytical formulas for the dependence of the particle mobility and diffusivity on the geometric channel parameters at zero and large applied drives. Finally, we rule out anomalous negative mobility for pointlike particles in a septate channel.

Transport in a one-dimensional symmetric device can be activated by the combination of thermal noise and a bi-harmonic drive. The results of extensive simulations allow us to distinguish between two apparently different bi-harmonic regimes: (i) harmonic mixing, where the two drive frequencies are commensurate but not too high; (ii) vibrational mixing, where one harmonic drive component possesses a high frequency but finite amplitude-to-frequency ratio. A comparison with the earlier theoretical predictions shows that at present the analytical understanding of nonlinear frequency mixing is still not satisfactory.

An AC driven, noiseless, underdamped Brownian particle moving on an asymmetric periodic substrate provides an interesting example of deterministic ratchet: In the adiabatic regime periodic and chaotic trajectories coexist on fine tuning the amplitude of the input signal; the transition from regular to chaotic transport happens through an intermediate class of trajectories exhibiting confined chaos.

We have reported the sequences of four novel proteins derived from extracts of human aortic tissue and a cDNA library from human aortic adventitia. These proteins are immunoreactive with serum immunoglobulins from patients with abdominal aortic aneurysms (AAA), and they have homologies of amino acid sequence with microfibrillar proteins of connective tissue. We are reporting separately that two of these proteins are artery-specific antigenic proteins (ASAPs) in man. The present work investigates the regional distribution of these two proteins (AAAP-40 and MatCAM-1) in mouse (E-beta-b). Antibodies were raised in rabbit against polypeptides encoding novel amino acid sequences, unique to these proteins (e.g., not reported in GenBank). Immunohistochemical studies with these two specific antibodies show conspicuous immunoreactivity of collagen-associated microfibrils in the aortic adventitia of the murine abdominal and thoracic aorta. Immunoreactive peptides were not present in brain, muscle, or kidney. These findings support the hypothesis that proteins occur in the mouse that are homologous to a unique family of aortic microfibrillar proteins in man.

In a recent experiment [M\"uller et al., Phys. Rev. A 79, 031804(R) (2009)] reported a splitting of the stochastic resonance peak, which they attributed to the asymmetry of an effective double-well restoring potential in their optomechanical read-out device. We show here that such an effect, though smaller than reported, is indeed consistent with a characterization of stochastic resonance as a synchronization phenomenon, while it proves elusive in terms of spectral quantifiers.

We consider stochastic resonance in a continuous cyclostationary one dimensional process. For an appropriate choice of the control parameters (e.g., as the result of an underlying higher dimensional dynamics) the stationary probability density of the process may grow bimodal even in the absence of an energetic barrier: this is no sufficient condition for stochastic resonance to occur.

Diffusion of an overdamped Brownian particle on a symmetric periodic substrate is investigated in the presence of pulsated perturbations of two kinds: (i) Stepwise lateral displacements (flashing substrate) and (ii) instantaneous tilts (shot noise). Pulses are applied, as it is often observed, in either periodic or random sequences with assigned mean (bias) and average waiting time (time constant). For a given bias, both the diffusion coefficient and the mobility of the particle can be greatly enhanced by tuning the time constant. Moreover, also depending on the time constant, the mobility can grow negative in (i) or exceed unity in (ii). We term this phenomenon resonant transport.

Waves or pulses propagating along periodic structures cause thermally controlled transport of diffusing defects. The dragging waves/pulses may modulate the amplitude of the substrate as well as the geometry of the boundaries where the defects are confined. The transport efficiency of such a mechanism attains its maximum for an optimal value of the temperature and the modulation speed.

Brownian motion on a symmetric vibrated periodic substrate is shown to be extremely sensitive to the particle mass even in the regime of large damping. This phenomenon is the most apparent for high vibration frequencies, a condition of technological interest, which is investigated here both analytically and numerically. When plotted versus the damping constant, both the particle mobility and the diffusion coefficient develop sharp (correlated) peaks, thus suggesting efficient schemes for separating submicron particles according to their mass or geometry.

The nonequilibrium escape dynamics in a bistable system under the influence of two Gaussian noises, one obtained by recycling, the other with a constant delay time, is shown by numerical simulation to exhibit stochastic synchronization; i.e., under stationary conditions, an appreciable fraction of renewal trajectories gets locked to the noise-recycling delay time. The conditions for optimal synchronization, reminiscent of stochastic resonance, are interpreted at any order within the framework of Kramers' theory.

Transport in a one-dimensional symmetric device can be activated by the combination of thermal noise and a bi-harmonic drive. For the study case of an overdamped Brownian particle diffusing on a periodic one-dimensional substrate, we distinguish two apparently different bi-harmonic regimes: (i) Harmonic mixing, where the two drive frequencies are commensurate and of the order of some intrinsic dynamical relaxation rate. A comparison of new simulation results with earlier theoretical predictions shows that the analytical understanding of this frequency mixing mechanism is not satisfactory, yet; (ii) Vibrational mixing, where one harmonic drive component is characterized by a high frequency but finite amplitude-to-frequency ratio. Its effect on the device response to either a static or a low-frequency additional input signal is accurately reproduced by rescaling each spatial Fourier component of the substrate potential, separately. Contrary to common wisdom based on the linear response theory, we show that extremely high-frequency modulations can indeed influence the response of slowly (or dc) operated devices, with potential applications in sensor technology and cellular physiology. Finally, the mixing of two high-frequency beating signal is also investigated both numerically and analytically., Comment: 8 pages, 9 figures

The one-dimensional motion of a massless Brownian particle on a symmetric periodic substrate can be rectified by reinjecting its driving noise through a realistic recycling procedure. If the recycled noise is multiplicatively coupled to the substrate, the ensuing feedback system works like a passive Maxwell's daemon, capable of inducing a net current that depends on both the delay and the autocorrelation times of the noise signals. Extensive numerical simulations show that the underlying rectification mechanism is a resonant nonlinear effect: The observed currents can be optimized for an appropriate choice of the recycling parameters with immediate application to the design of nanodevices for particle transport.

A Brownian particle hopping in a symmetric double-well potential may be statistically confined into a single well by the simultaneous action of two periodic input signals, one tilting the minima, the other one modulating the barrier height. Such a basic mechanism for asymmetric confinement can be conveniently maximized by tuning the input signal parameters (frequencies, phase lag, amplitudes), thus leading to a resonant localization of the particle in a target potential well.

A Brownian particle hopping in a symmetric double-well potential can be statistically confined into a single well by the simultaneous action of (a) two periodic input signals, one tilting the minima and the other one modulating the barrier height, and (b) an additive and a purely multiplicative random signal, generated by a unique source and thus preserving a certain degree of statistical correlation. The underlying gating mechanism is quite robust when compared, for instance, with biharmonic rocking. In view of technological implementation, asymmetric confinement through gating can be conveniently maximized by tuning the input signal parameters (correlation time, phase-time lag, amplitudes), thus revealing a resonant localization mechanism of general applicability.

The dynamics of a vibrated bouncing ball is studied numerically in the reduced impact representation, where the velocity of the bouncing ball is sampled at each impact with the plate (asynchronous sampling). Its random nature is thus fully revealed: (i) the chattering mechanism, through which the ball gets locked on the plate, is accomplished within a limited interval of the plate oscillation phase, and (ii) is well described in impact representation by a special structure of looped, nested bands and (iii) chattering trajectories and strange attractors may coexist for appropriate ranges of the parameter values. Structure and substructure of the chattering bands are well explained in terms of a simple impact map rule. These results are of potential application to the analysis of high-temperature vibrated granular gases.

The rectification of a massive Brownian particle moving on a periodic substrate can be achieved in the absence of spatial asymmetry, by having recourse to (at least) two periodic, zero-mean input signals. We determine the relevant drift current under diverse operation conditions, namely, additive and multiplicative couplings, adiabatic and fast oscillating drives, and propagating substrate modulations. Distinct rectification mechanisms result from the interplay of noise and commensuration of the input frequencies, mediated through the nonlinearity of the substrate. These mechanisms are then extended to characterize soliton transport along a directed multistable chain. As the side-wise soliton diffusion is ultimately responsible for the transverse diffusion of such chains, our approach provides a full account of the Brownian motion of both pointlike and linear objects on a periodic substrate.

Amyloid-containing (A+) islets are characteristic for type-2 diabetes (T2D), but their abundance seems variable among patients. It is unclear whether the distribution of A+ islets follows a certain pattern or occurs randomly throughout the pancreatic organ. We investigated the topography of A+ islets in eight pancreata of T2D patients and eight sex- and age-matched non-diabetic subjects. Transversal sections of head, body and tail segments were stained with synaptophysin combined with Congo red to map/quantify islet tissue and amyloid. In the eight T2D pancreata, the overall percentage of A+ islets varied from 4% to 85%. Further analysis in body and tail indicated that peripheral regions exhibited higher percentages of A+ islets than central regions (averages of, respectively, 30% and 17%, P

A Brownian particle hopping in a symmetric double-well potential can be statistically confined to a single well by the simultaneous action of a) two periodic input signals, one tilting the minima, the other one modulating the barrier height; b) an additive and a purely multiplicative random signal, generated by a unique source and thus preserving a certain degree of statistical correlation. In view of technological implementation, such a basic mechanism for asymmetric confinement can be conveniently maximized by tuning the input signal parameters (correlation time, phase/time lag, amplitudes), thus revealing a resonant localization mechanism of wide applicability.

25 humeral shaft fractures operated on at our institute with the intramedullary elastic Marchetti-Vicenzi nail were reviewed. Three were pathologic fractures. Patients mean age was 48 ranging from 13 to 95 years. The patients were followed until consolidation and shoulder and elbow function were evaluated with respectively the Constant and the Mayo Clinic score. All the fractures eventually healed with good clinical results. There were no major complications during nail insertion. The M-V nail has been shown to be a practical and reliable device, characterised by both an easy technique and a stable fixation, with a low complication rate and low X-rays exposure times. The choice of an elastic unreamed intramedullary nail, with a retrograde insertion, that allows a solid for proximal fixation by means of a bundle of divergent pins, has proven to be useful and safe for shoulder function.

A linear defect, viz. an elastic string, diffusing on a planar substrate traversed by a travelling wave experiences a drag known as Stokes' drift. In the limit of an infinitely long string, such a mechanism is shown to be characterized by a sharp threshold that depends on the wave parameters, the string damping constant and the substrate temperature. Moreover, the onset of the Stokes' drift is signaled by an excess diffusion of the string center of mass, while the dispersion of the drifting string around its center of mass may grow anomalous., 14 pages, no figures, to be published in Phys.Rev.B

We simulated numerically the time evolution of a one-kink bearing, damped elastic string sitting on noiseless periodic substrates of two types: (I) asymmetric, time independent, (II) symmetric, periodically deformable. An asymmetric kink subjected to an ac drive is shown to drift steadily with finite average speed independent of its initial kinetic conditions. In the overdamped regime the resulting net kink transport can be attributed to the rectification of the Brownian motion of a pointlike particle with oscillating mass. For intermediate to low damping completely different features show up, due to the finite size of the objects being transported; in particular, the kink current hits a maximum for an optimal value of the damping constant, resonates at the kink internal-mode frequency and, finally, reverses sign within a certain range of the drive parameters.

The rectification efficiency of an underdamped ratchet operated in the adiabatic regime increases according to a scaling current-amplitude curve as the damping constant approaches a critical threshold; below threshold the rectified signal becomes extremely irregular and eventually its time average drops to zero. Periodic (locked) and diffusive (fully chaotic) trajectories coexist on fine tuning the amplitude of the input signal. The transition from regular to chaotic transport in noiseless ratchets is studied numerically., 9 pages, 5 figures, to be published in Phys. Rev. E

Members of the family of Sp transcription factors include Sp1, Sp3, and Sp4 and are important regulators of eukaryotic gene expression. We previously reported that Sp1 mediated stimulation of rat calmodulin I gene expression in response to insulin. To test whether other members of the Sp family are direct targets of insulin action, we compared the levels of Sp1 and Sp3 proteins from nuclear extracts obtained from both insulin-treated and untreated rat hepatoma (H-411E) cells. We demonstrated by Western blot analysis that levels of Sp1 and Sp3 proteins were increased more than 2-fold in the insulin-treated group. Additionally, the up-regulation of both Sp1 and Sp3 transcription factors by insulin was antagonized by tumor necrosis factor-alpha, a known inhibitor of insulin action. Immunohistochemical analysis demonstrated that H-411E cells treated with insulin (10,000 microU/ml) had a marked increase in demonstrable Sp1 in the nucleus compared with cells incubated in insulin-free medium. We extended these in vitro observations to in vivo studies in the streptozotocin-diabetic rat model. We demonstrated in rat liver tissue by both Western blot and immunohistochemical staining with anti-Sp1 antibody that 1) livers of fully diabetic streptozotocin rats have low levels of Sp1 transcription factor; and 2) insulin treatment of the diabetic rat rapidly reversed this process by markedly stimulating accumulation of Sp1 in rat liver. Studies of the signal transduction mechanisms involved in insulin's effect on Sp1 demonstrate a facilitating role for phosphoinositol 3-kinase and an inhibitory role for cyclic nucleotides. In summary, insulin stimulates Sp1 protein, a transcription factor that is shown to regulate calmodulin gene expression and most likely other, as yet untested, genes.

A driven Brownian particle (e.g. an adatom on a surface) diffusing on a low-viscosity, periodic substrate may execute multiple jumps. In the presence of an additional periodic drive, the jump lengths and time durations become statistically modulated according to a syncronyzation mechanism reminiscent of asymmetric stochastic resonance. Here, too, bistability plays a key role, but in a dynamical sense, inasmuch as a particle switches between locked and running states., 4 pages, 4 figures, RevTeX, to be published in Surface Science Letters

Driven diffusion of a Brownian particle along a one-dimensional lattice is investigated numerically on decreasing its damping constant. The notions of multiple jumps, jump reversal, and backward-to-forward rates are discussed in detail. In particular, we conclude that in the underdamped limit backward jumps are suppressed relative to forward jumps more effectively than previously assumed. The dependence of such a drive-controlled mechanism on the damping constant and the temperature is interpreted analytically.

The escape times of an overdamped Brownian particle confined to a quartic bistable potential is known to be extremely sensitive to the fluctuation correlation time. In the presence of an external Gaussian noise source with fixed variance, the escape times develop a minimum for a certain value of the correlation time—a behavior reminiscent of the so-called resonant activation phenomenon. The optimal escape conditions are investigated for a wide range of the noise variance.

Thermal nucleation of kink-antikink pairs in an elastic string subjected to a washboard potential is analyzed in the classical limit at low temperature. The nucleation rate is calculated analytically for values of the tilt up to close the instability threshold. Numerical simulation is shown to support our predictions in the diverse parameter regimes.

The nuclear single-particle spectral function is considered in the region of high momentum and high removal energy. For these kinematical conditions, far away from the quasi-particle peak, the spectral function is expected to be dominated by nucleon-nucleon correlations. It has been previously argued that the spectral function can be written as a convolution between the two-body relative momentum distribution and the corresponding centre-of-mass distribution of the correlated pairs which characterize the structure of the ground state in this energy-momentum region. It is shown that the convolution model can be microscopically derived from the Brueckner-Bethe-Goldstone (BBG) expansion. At the same time, this result also allows us to establish a direct link between the spectral function and the defect function of the BBG theory. From a numerical comparison with the microscopic spectral function the convolution model turns out to be highly accurate in the relevant momentum and energy range.

In eccentric septate channels the pores connecting adjacent compartments are shifted off-axis, either periodically or randomly, so that straight trajectories parallel to the axis are not allowed. Driven transport of a Brownian particle in such a channel is characterized by a strong suppression of the current and its dispersion. For large driving forces, both quantities approach an asymptotic value, which can be analytically approximated in terms of the stationary distribution of the particle exit times out of a single channel compartment.

Non-ulcer dyspepsia (NUD) is a common complaint in which no systematic illness or organic proximal alimentary tract disease can be identified. The pathophysiology of NUD is probably heterogeneous. Eighty-two subjects with NUD were studied in a prospective randomized placebo-controlled study to assess the efficacy of colloidal bismuth subcitrate (CBS) chewable tablets at a dose of four tablets daily for 1 month. The role of Campylobacter pylori and associated histological gastritis was evaluated. Sixty-one percent of NUD patients had C. pylori in the gastric antrum compared with 25% of age-matched controls. C. pylori was associated with acute and chronic inflammation (P less than 0.001) in the antrum. C. pylori was cleared in 59% of CBS-treated subjects compared with only 4% placebo (P less than 0.05). Both acute and chronic inflammation improved in subjects cleared of bacteria. Clearance of C. pylori and histological improvement was associated with a significant decrease in symptoms. In C. pylori negative subjects improvement in symptoms occurred in both the placebo and active treatment groups. This study would suggest that C. pylori and associated histological gastritis may play a role in non-ulcer dyspepsia.

A large fraction of the damping width of the giant-dipole resonance in a hot nucleus arises from the coupling of the giant vibration to thermal fluctuations of the nuclear surface. It is expected, on general grounds, that this coupling displays a marked dependence on the temperature, becoming progressively less effective as T increases over a critical value, estimated to be ∼ 1 MeV.

A recently developed non-relativistic method for calculating the nucleon optical-model potential has been employed to evaluate the contributions from isobaric degrees of freedom to the imaginary part of the nucleon optical-model potential. To evaluate the imaginary part of the optical-model potential, we include the contributions from terms to second order in the Brueckner G -matrix with and without the inclusion of isobars Δ. Results for 16 O are presented in this work. The contributions to the imaginary part are given by the two-particle-one-hole (2p1h) and three-particle-two-hole (3p2h) diagrams. The latter contributes at negative energies only and the contribution from isobar intermediate states is rather small. The 2p1h diagram receives significant contributions from isobars at energies near the resonance and above the threshold for the excitation of ΔΔ states. In particular the importance of ΔΔ configurations is rather sensitive to the treatment of short-range correlations. The parameterization of the self-energy in terms of local potentials is discussed. The depletion of the occupation of the single-particle orbits due to nucleon-nucleon correlations and Δ-excitations is evaluated.