Radiation 'damping' in atomic photonic crystals

The force exerted on a material by an incident beam of light is dependent upon the material's velocity in the laboratory frame of reference. This velocity dependence is known to be diffcult to measure, as it is proportional to the incident optical power multiplied by the ratio of the material velocity to the speed of light. Here we show that this typically tiny effect is greatly amplified in multilayer systems composed of resonantly absorbing atoms (e.g. optically trapped 87Rb), which may exhibit ultra-narrow photonic band gaps. The amplification of the effect is shown to be three orders of magnitude greater than previous estimates for conventional photonic-band-gap materials, and significant for material velocities of a few ms/s.Comment: 5 pages, 3 figure

Perinatal stem cells revisited: directions and indications at the crossroads between tissue regeneration and repair.

Perinatal stem cells research attracted great interest worldwide in recent years. Foetus-associated tissues contain various populations of stem cells, most of which are comprised within the category of mesenchymal stem cells (MSCs). This special issue collects both reviews and original reports on all the perinatal stem cell types which are currently under investigation. These cells have multiple promising features: differentiative capacity towards mature cell types of all the three germ layers, hypoimmunogenicity in vitro and in vivo, ease of sourcing, ex vivo culture and stor- age. In particular, immune modulation is viewed as a prom- ising feature of many MSCs populations, since these cells, once administered therapeutically, may be able to overcome, or at least evade, the host immune response which may lead to acute or chronic rejection of the transplant

Role of anisotropy in the F\"orster energy transfer from a semiconductor quantum well to an organic crystalline overlayer

We consider the non-radiative resonant energy transfer from a two-dimensional Wannier exciton (donor) to a Frenkel exciton of a molecular crystal overlayer (acceptor). We characterize the effect of the optical anisotropy of the organic subsystem on this process. Using realistic values of material parameters, we show that it is possible to change the transfer rate within typically a factor of two depending on the orientation of the crystalline overlayer. The resonant matching of donor and acceptor energies is also partly tunable via the organic crystal orientation.Comment: 6 pages, 8 figure

A Gas-Kinetic Model for Shallow Water Flows in Presence of Wet/Dry Fronts

Experimental and Computational Hydraulic

Spatial Kramers–Kronig relations and the reflection of waves

When a planar dielectric medium has a permittivity profile that is an analytic function in the upper or lower half of the complex position plane x = x′ + ix″ then the real and imaginary parts of its permittivity are related by the spatial Kramers–Kronig relations. We find that such a medium will not reflect radiation incident from one side, whatever the angle of incidence. Using the spatial Kramers–Kronig relations, one can derive a real part of a permittivity profile from some given imaginary part (or vice versa) such that the reflection is guaranteed to be zero. This result is valid for both scalar and vector wave theories and may have relevance for designing materials that efficiently absorb radiation or for the creation of a new type of anti-reflection surface

Synchronization in Scale Free networks: The role of finite size effects

Synchronization problems in complex networks are very often studied by researchers due to its many applications to various fields such as neurobiology, e-commerce and completion of tasks. In particular, Scale Free networks with degree distribution $P(k)\sim k^{-\lambda}$, are widely used in research since they are ubiquitous in nature and other real systems. In this paper we focus on the surface relaxation growth model in Scale Free networks with $2.5< \lambda <3$, and study the scaling behavior of the fluctuations, in the steady state, with the system size $N$. We find a novel behavior of the fluctuations characterized by a crossover between two regimes at a value of $N=N^*$ that depends on $\lambda$: a logarithmic regime, found in previous research, and a constant regime. We propose a function that describes this crossover, which is in very good agreement with the simulations. We also find that, for a system size above $N^{*}$, the fluctuations decrease with $\lambda$, which means that the synchronization of the system improves as $\lambda$ increases. We explain this crossover analyzing the role of the network's heterogeneity produced by the system size $N$ and the exponent of the degree distribution.Comment: 9 pages and 5 figures. Accepted in Europhysics Letter

The role of flower pollen extract in managing patients affected by chronic prostatitis/chronic pelvic pain syndrome. a comprehensive analysis of all published clinical trials

Background: Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is still a challenge to manage for all physicians. We feel that a summary of the current literature and a systematic review to evaluate the therapeutic efficacy of flower pollen extract would be helpful for physicians who are considering a phytotherapeutic approach to treating patients with CP/CPPS. Methods: A comprehensive search of the PubMed and Embase databases up to June 2016 was performed. This comprehensive analysis included both pre-clinical and clinical trials on the role of flower pollen extract in CP/CPPS patients. Moreover, a meta-analysis of available randomized controlled trials (RCTs) was performed. The NIH Chronic Prostatitis Symptom Index (NIH-CPSI) and Quality of Life related questionnaires (QoL) were the most commonly used tools to evaluate the therapeutic efficacy of pollen extract. Results: Pre-clinical studies demonstrated the anti-inflammatory and anti-proliferative role of pollen extract. 6 clinical, non-controlled studies including 206 patients, and 4 RCTs including 384 patients were conducted. The mean response rate in non-controlled studies was 83.6% (62.2%-96.0%). The meta-analysis revealed that flower pollen extract could significantly improve patients’ quality of life [OR 0.52 (0.34-.0.81); p = 0.02]. No significant adverse events were reported. Conclusion: Most of these studies presented encouraging results in terms of variations in NIH-CPSI and QoL scores. These studies suggest that the use of flower pollen extract for the management of CP/CPPS patients is beneficial. Future publications of robust evidence from additional RCTs and longer-term follow-up would provide more support encouraging the use of flower pollen extracts for CP/CPPS patients