Spatiotemporal discrete surface solitons in binary waveguide arrays

We study spatiotemporal solitons at the edge of a semi-infinite binary array of optical waveguides and, in particular, predict theoretically the existence of a novel type of surface soliton, the surface gap light bullets. We analyze the stability properties of these solitons in the framework of the continuous-discrete model of an array of two types of optical waveguides

Soliton content with quadratic nonlinearities

Summary form only given. Quadratic solitons, that form through cascading in materials with second-order nonlinearities, are a topic of current intense investigation. Solitons have been observed in second harmonic generation (SHG) and in parametric amplification schemes, and many of their basic properties are well established. In particular, families of spatial and temporal solitons existing in waveguides and in bulk geometries are known, including those existing in settings with a small Poynting vector walk-off and/or temporal group-velocity mismatch. Under conditions where modulational instabilities can not grow, such families of solitons are stable under propagation and robust against several perturbations.Peer ReviewedPostprint (published version

Spatial walking solitons in quadratic nonlinear crystals

We investigate the properties of the families of spatial walking solitons propagating in planar waveguides made of quadratic nonlinear media under conditions for second-harmonic generation in the presence of Poynting vector walk-off. We study in detail the shape and various features of the solitons, their stability on propagation, and their excitation.Peer Reviewe

Vortex stability in nearly two-dimensional Bose-Einstein condensates with attraction

We perform accurate investigation of stability of localized vortices in an effectively two-dimensional ("pancake-shaped") trapped BEC with negative scattering length. The analysis combines computation of the stability eigenvalues and direct simulations. The states with vorticity S=1 are stable in a third of their existence region, $0<N<(1/3)N_{\max}^{(S=1)}$, where $N$ is the number of atoms, and $N_{\max}^{(S=1)}$ is the corresponding collapse threshold. Stable vortices easily self-trap from arbitrary initial configurations with embedded vorticity. In an adjacent interval, $(1/3)N_{\max }^{(S=1)}<N<$ $\allowbreak 0.43N_{\max}^{(S=1)}$, the unstable vortex periodically splits in two fragments and recombines. At $N>$ $\allowbreak 0.43N_{\max}^{(S=1)}$, the fragments do not recombine, as each one collapses by itself. The results are compared with those in the full 3D Gross-Pitaevskii equation. In a moderately anisotropic 3D configuration, with the aspect ratio $\sqrt{10}$, the stability interval of the S=1 vortices occupies $\approx 40$ of their existence region, hence the 2D limit provides for a reasonable approximation in this case. For the isotropic 3D configuration, the stability interval expands to 65% of the existence domain. Overall, the vorticity heightens the actual collapse threshold by a factor of up to 2. All vortices with $S\geq 2$ are unstable.Comment: 21 pages, 8 figures, to appear in Physical Review

Modern Tools for Diagnosis in Tuberculous Ascites

Tuberculosis (TB) is a highly contagious bacterial infection caused by Mycobacterium tuberculosis (MTB), affecting about 1/3rd of the world population and being responsible for lot of deaths worldwide, despite the progress achieved in the diagnosis and treatment fields. TB can affect the peritoneum, the TB ascites being a concern for physicians, especially when dealing with immunocompromised patients. The clinical presentation of TB ascites is challenging, due to nonspecific symptoms that make confusion with other diseases and the late results of cultures from ascites. The late diagnosis leads to a delayed treatment and high mortality. This manuscript describes recent tools used for early diagnosis in TB ascites. Molecular methods based on mycobacterial nucleic acid amplification tests (NAATs), polymerase chain reaction (PCR) detecting minimal amounts of bacterial DNA, or interferongamma release assays (IGRA) and biochemical methods such as the serum-ascites albumin gradient (SAAG) 40 UI/ml were recently considered more accurate diagnostic procedures. These methods allow a rapid and accurate differential diagnosis of ascites fluid, making possible the early treatment with appropriate drugs

Is a Fecal Microbiota Transplant Useful for Treating Inflammatory Bowel Disease?

Ulcerative colitis and Crohn’s disease represent the major groups of idiopathic disorders in inflammatory bowel disease (IBD). The etiology includes environmental factors, genetic factors, and immune responses. The pathogenesis is diversified; however, no guaranteed curative therapeutic regimen has been developed so far. This review contains information related to pathophysiology and current treatment options for IBD. It is known that IBD is caused by tissue-disruptive inflammatory reactions of the gut wall; that is why downregulation of the immune responses allows the healing of the damaged mucosa and allows the resetting of the physiological functions of the gut back to normal. The main treatment options are still corticosteroids, immunomodulators, antibiotics, probiotics, and a series of new agents. Their effects include modulation of cytokines, neutrophil-derived factors, adhesion molecules, and reactive oxygen/nitrogen metabolites. The monoclonal antitumor necrosis factor as infliximab recombinant anti-inflammatory cytokines or related gene therapy is also used nowadays. Still, the fecal microbiota transplantation (FMT) is considered to revolutionize the therapy in IBD, considering the abnormal inflammatory response due to the complicated relationship between microbiota and the immune system. It is imperative to mention the critical role dysbiosis may have in the pathogenesis of IBDs. This review summarizes the available literature concerning the efficacy of FMT in IBDs

Modern approaches for antiandrogen-resistant prostate cancer therapy

Prostate cancer represents the leading malignant tumor in men over 50 years of age with 400,000 new cases being diagnosed yearly in Europe. Even if the incidence rate is higher than the mortality rate, still there is an increasing trend when speaking of its mortality. The increasing incidence of the metabolic syndrome, the unhealthy lifestyle, the high lipid and Calcium intake, the high spread of infections with Human Papilloma Virus, Human Herpes Virus, the excess of androgen consumption and the longer life expectancy, are few of the main causes of prostate cancer increasing incidence. The new systemic therapies such as immunotherapy with Checkpoint Inhibitors or Poly, ADP-Ribose Polymerase inhibitors and local experimental procedures addressing tumor destruction, such as High- Intensity Focused Ultrasound, the Cryo and Focal Laser Ablation, provide good outcomes and become new promising tools for prostate cancer therapy. Physicians consider these methods worth using; the efficacy of some specific categories of patients being arguments for their use in the current protocols even though solid data regarding the improvement of global mortality rates are not yet published. The current article focuses on the newest systemic and local experimental treatment tools highlighting their benefits, especially for hormone-resistant prostate cancer

Finite Element Analysis of a Novel Aortic Valve Stent

Worldwide, one of the leading causes of death for patients with cardiovascular disease is aortic valve failure or insufficiency as a result of calcification and cardiovascular disease. The surgical treatment consists of repair or total replacement of the aortic valve. Artificial aortic valve implantation via a percutaneous or endovascular procedure is the minimally invasive alternative to open chest surgery, and the only option for high-risk or older patients. Due to the complex anatomical location between the left ventricle and the aorta, there are still engineering design optimization challenges which influence the long-term durability of the valve. In this study we developed a computer model and performed a numerical analysis of an original self-expanding stent for transcatheter aortic valve in order to optimize its design and materials. The study demonstrates the current valve design could be a good alternative to the existing commercially available valve devices