On Dissipation Rate of Ocean Waves due to White Capping

We calculate the rate of ocean waves energy dissipation due to whitecapping by numerical simulation of deterministic phase resolving model for dynamics of ocean surface. Two independent numerical experiments are performed. First, we solve the $3D$ Hamiltonian equation that includes three- and four-wave interactions. This model is valid for moderate values of surface steepness only, $\mu < 0.09$. Then we solve the exact Euler equation for non-stationary potential flow of an ideal fluid with a free surface in $2D$ geometry. We use the conformal mapping of domain filled with fluid onto the lower half-plane. This model is applicable for arbitrary high levels of steepness. The results of both experiments are close. The whitecapping is the threshold process that takes place if the average steepness $\mu > \mu_{cr} \simeq 0.055$. The rate of energy dissipation grows dramatically with increasing of steepness. Comparison of our results with dissipation functions used in the operational models of wave forecasting shows that these models overestimate the rate of wave dissipation by order of magnitude for typical values of steepness.Comment: 6 pages, 2 figure

New high magnetic field phase of the frustrated S=1/2S=1/2 chain compound LiCuVO4_4

Magnetization of the frustrated $S=1/2$ chain compound LiCuVO$_4$, focusing on high magnetic field phases, is reported. Besides a spin-flop transition and the transition from a planar spiral to a spin modulated structure observed recently, an additional transition was observed just below the saturation field. This newly observed magnetic phase is considered as a spin nematic phase, which was predicted theoretically but was not observed experimentally. The critical fields of this phase and its dM/dH curve are in good agreement with calculations performed in a microscopic model (M. E. Zhitomirsky and H. Tsunetsugu, preprint, arXiv:1003.4096v2).Comment: 5 pages, 4 figure

Efficiency determination of resistive plate chambers for fast quasi-monoenergetic neutrons

Composite detectors made of stainless steel converters and multigap resistive plate chambers have been irradiated with quasi-monoenergetic neutrons with a peak energy of 175MeV. The neutron detection efficiency has been determined using two different methods. The data are in agreement with the output of Monte Carlo simulations. The simulations are then extended to study the response of a hypothetical array made of these detectors to energetic neutrons from a radioactive ion beam experiment.Comment: Submitted to Eur.Phys.J. A; upgraded version correcting some typos and updating ref.

Experimental Cell Line Models for Nephrotoxicity Screening

The aim of the study was to review literature data on cell models for experimental assessment of drug nephrotoxicity in vitro. Because of nephrotoxicity, 2% of new investigational medicinal products are discarded at the stage of preclinical in vivo studies in laboratory animals, and 19%—after phase 3 clinical trials. Prediction of toxicity in cell models could make drug development more cost-effective and help to reduce/avoid animal testing. At present, there are no official international guidelines for assessment of nephrotoxicity in vitro, but there is a lot of research underway. The main toxicity target in kidneys is renal proximal tubule epithelial cells, therefore the main research is focused on the development of renal proximal tubule epithelial cell lines with stable functional characteristics. Another important aspect in nephrotoxicity modeling is the choice of relevant test methods and end points which would reflect potential toxicity mechanisms. The paper reviews existing human renal proximal tubule epithelial cell lines and current test methods for assessing cytotoxicity. Promising areas for future development of cell models for nephrotoxicity assessment— are optimisation and standardisation of in vitro systems that would help to make preclinical predictions of drug nephrotoxicity in vivo

Mechanism of Pion Production in alphaalphap Scattering at 1 GeV/nucleon

The one-pion and two-pion production in the p(alpha, alpha prime)X reaction at an energy of E{alpha} = 4.2 GeV has been studied by simultaneous registration of the scattered alpha particles and the secondary pion or proton. The obtained results demonstrate that the inelastic alpha-particle scattering on the proton at the energy of the experiment proceeds either through excitation and decay of Delta resonance in the projectile or through excitation in the target proton of the Roper resonance, which decays mainly on a nucleon and a pion or a nucleon and a sigma meson - system of two pions in the isospin I = 0, S-wave.Comment: 16 pages, 10 figures. Submitted to Proceedings of the XX International Baldin Seminar on High - Energy Physics Problems, Dubna, October 4 - 9, 201

Evaluation of the Effect of Comorbidity on the Efficacy and Safety of β-Lactam Antibiotics in Patients with Community-Acquired Pneumonia

Lower respiratory tract infections, which include community-acquired pneumonia (CAP), are the most common cause of death among all infectious diseases. The presence of a comorbid pathology in a patient with CAP suggests a possibility of mutual influence and changes in the course of both the underlying disease and comorbidities, as well as changes in the effectiveness and safety of ongoing drug therapy. The aim of the study was to analyse literature data on the structure of comorbidity in CAP patients and its impact on the efficacy and safety of therapy with β-lactam antibiotics. It has been established that CAP most often occurs in patients with chronic obstructive pulmonary disease, cardiovascular diseases (ischemic heart disease, arterial hypertension, and chronic heart failure), cerebrovascular disease, chronic kidney disease, diabetes mellitus, bronchial asthma, leukemia, anemia, dementia, neurological disorders, and cancer. The most common causative agent of CAP, regardless of the patient’s age and comorbidity, is pneumococcus (Streptococcus pneumoniae), followed by intracellular pathogens (mycoplasmas, chlamydia) and Haemophilus influenzae, as well as respiratory viruses. With this in mind, the initial empiric therapy for CAP mainly includes β-lactam antibiotics, which are effective against pneumococcus. If patients with CAP have concomitant chronic diseases and conditions, the spectrum of pneumonia pathogens may differ from that in the general population and include rare pathogens and multidrug-resistant strains. The effectiveness of antibiotic therapy in such patients is reduced, which leads to a worsening of the course of both CAP and concomitant diseases. This patient population may require longer treatment with antibiotics, including β-lactams, or the use of antibiotics at doses that provide a higher minimum inhibitory concentration, which is associated with a high risk of adverse reactions and a decrease in the safety of antibiotic therapy