Electron Mass Operator in a Strong Magnetic Field and Dynamical Chiral Symmetry Breaking

The electron mass operator in a strong magnetic field is calculated. The contribution of higher Landau levels of virtual electrons, along with the ground Landau level, is shown to be essential in the leading log approximation. The effect of the electron dynamical mass generation by a magnetic field is investigated. In a model with N charged fermions, it is shown that some critical number N_{cr} exists for any value of the electromagnetic coupling constant alpha, such that the fermion dynamical mass is generated with a doublet splitting for N < N_{cr}, and the dynamical mass does not arise at all for N > N_{cr}, thus leaving the chiral symmetry unbroken.Comment: 4 pages, REVTEX4, 3 figure

Implications of Primary Cilia and Associated Lysophosphatidic Acid Signaling in Glioblastoma Biology and Therapy

The primary cilium is a ubiquitous organelle presented on most human cells. It serves as a crucial signaling hub for multiple pathways including growth factor and G-protein coupled receptors. Loss of primary cilia was observed in various cancers, however, the implications of this event are unclear. Several studies show that loss of cilia promotes cell proliferation, suggesting that alteration of ciliary-dependent signaling can drive the hyperproliferative phenotype of cancer cells, therefore re-establishing primary cilia or targeting altered signaling pathways could be a beneficial strategy as an anti-cancer therapy.;Glioblastoma (GBM) is one of the deadliest cancers with a median survival of 14 months. Such rapid progression of the disease is usually due to the very high growth rate of the tumor and rapid recurrence after surgical resection. Current standard of care for GBM patients includes aggressive radiation and chemotherapy, thus there is a high demand for more targeted approaches. Primary cilia formation is drastically decreased in GBM, however, the role of cilia in glioblastoma proliferation has not been explored. The overall aim of this work was to elucidate the mechanisms of increases in proliferation driven by the loss of cilia, and utilize it to target GBM. The cellular origins of GBM are currently under debate. One of the potential candidates are astrocytes, a highly abundant type of cell in the brain. Loss of primary cilia in human astrocytes stimulates proliferation in the presence of serum. Lysophosphatidic acid (LPA) was found to be a serum component responsible for this phenotype. Lysophosphatidic acid receptor 1 (LPAR1), a G-protein coupled receptor, was found to be accumulated in primary cilium in both astrocytes and GBM cells when cilium was present, while previously reported interactors of LPAR1, Galpha 12 and Galphaq, were excluded from cilium. LPAR1 signaling through Galpha12/Galphaq was previously reported to be responsible for cancer cell proliferation. Such compartmentalization in ciliated cells creates a barrier against unlimited proliferation, which is one of the hallmarks of cancer.;Inhibition of LPA signaling with the small molecule compound Ki16425 in deciliated, highly proliferative astrocytes or GBM cells/xenografts drastically suppresses their growth both in vitro and in vivo. Moreover, Ki16425 brain delivery via PEG-PLGA nanoparticles inhibited tumor progression in an intracranial glioblastoma patient-derived xenograft (PDX) model. Overall, in the current studies, a novel mechanism by which primary cilium restricts proliferation was established. Loss of primary cilia is sufficient to increase mitogenic signaling, and is important for the maintenance of a highly proliferative cancer phenotype. Clinical application of LPA inhibitors may prove beneficial to restrict glioblastoma proliferation and ensure local control of the disease

Numerical modelling of radiant energy extinction by water medium containing bubbles and particles of various natures

In the framework of the Mie theory, we developed a numerical model of weakly absorbing medium, containing particles having an arbitrary chemical composition. This model can be applied to the study of the extinction characteristics of the optical radiation by a water layer with gas bubbles or volume-shape particles. The results of the numerical experiment illustrate changes in optical properties of the water due to the presence of bubbles or solid particles. The work displays some calculations of the extinction efficiency factor, the extinction coefficient, and transmission function at visible wavelengths. The influences of concentration and sizes of gas bubbles on the extinction characteristics of optical radiation are illustrated. Features of the extinction of radiant energy are discussed as dependent on a size parameter and a complex index of refraction of scatterers

Electron mass operator in a strong magnetic field

The electron mass operator in a strong magnetic field is calculated by summation of the leading log contributions in all orders of the perturbation theory. An influence of the strong field on the virtual photon polarization operator is taken into account. The contribution of higher Landau levels of virtual electrons, along with the ground Landau level, is shown to be essential in the leading log approximation.Comment: 7 pages, LATEX, 1 PS figure, submitted to Modern Physics Letters

The impact of obesity on the structure of osteoarthrosis of large joints of the lower limb.

The prevalence of osteoarthrosis (OA) among adults over 40 years is taking one of the leading places in the common structure of joint pathology. Obesity – is of the comorbidities associated with OA, one of the risk factors of development and progression of OA. The aim of this study was to evaluate the influence of obesity on the structure of knee and hip OA on the stage of total joint replacement, depending on the patient`s gender, age and degree of obesity. The study involved 170 inpatient case histories of patients with OA undergoing treatment in the department of  large joints replacement (64 men and 106 women): 95 patients with OA of hip joint and 75 – with OA of knee joint, among whom there were 110 patients with obesity and 60 – without it. The middle age of the patients was by 63,8±7,69 years. High prevalence of obesity among patients with OA of knee and hip joints was found, with significant higher number of obese patients with OA of knee joint and among female patients. It has been demonstrated a significant increase in the frequency of total knee joint replacement associated with the increase of body mass index among patients with OA of knee joint. The presence of obesity was associated with earlier terms of the total joint replacement performing, especially among male patients

Errors and complications in hip arthroplasty using cement technology.

According to the latest qualitative European registers cement type of fixation of one or both components of the hip joint is used in 4,5-58 % of cases, and in Scandinavian countries the figure is close to 90%. Performing any kind of surgery on musculoskeletal system surgeon should be prepared for post-operative com­plications. This study presents analysis of errors and complications of 65 hip replacements using cement technology. The technical errors of hip replacement with cement technologies usage are: the uneven distribution of the cement mantle around the endoprosthesis components, incomplete filling of the femoral medullary canal and bed of acetabular bone with cement, incorrect position of the implant components in the bone bed. The nature and number of somatic complications after total cemented replacement, observed in the group of patients that we investigated were: a transient drop in blood pressure − 11 (78.6 %) cases, thrombophlebitis − 1 (7.1%) case, transient coronary arteries ischemia − 1 (7.1%) case, cerebrovascular complications − 1 (7.1%) case

Dependence of the Self-Diffusion Coefficient of Liquid Molecules in a Porous Medium on Its Geometric Parameters

Based on the most general concepts of the translational mobility and geometry of a porous medium, an expression is derived for the self-diffusion coefficient of liquid molecules in such a medium. An analytical relation between the self-diffusion coefficient and the effective geometric parameters of the pores, as well as the sizes of diffusant molecules, is proposed. The derived expression agrees well with experimental results