40 research outputs found
General Relativistic Effect of Gravitomagnetic Charge on Pulsar Magnetosphere and Particle Acceleration in a Polar Cap
We study magnetospheric structure surrounding rotating magnetized neutron
star with nonvanishing NUT (Newman-Tamburino-Unti) parameter. For the
simplicity of calculations Goldreich-Julian charge density is analyzed for the
aligned neutron star with zero inclination between magnetic field,
gravitomagnetic field and rotation axis. From the system of Maxwell equations
in spacetime of slowly rotating NUT star, second-order differential equation
for electrostatic potential is derived. Analytical solution of this equation
indicates the general relativistic modification of an accelerating electric
field and charge density along the open field lines by the gravitomagnetic
charge. The implication of this effect to the magnetospheric energy loss
problem is underlined. In the second part of the paper we derive the equations
of motion of test particles in magnetosphere of slowly rotating NUT star. Then
we analyze particle motion in the polar cap and show that NUT parameter can
significantly change conditions for particle acceleration.Comment: 21 pages, 6 figures, accepted for publication in Ap
Endonuclease domain of the Drosophila melanogaster R2 non-LTR retrotransposon and related retroelements: a new model for transposition
The molecular mechanisms of the transposition of non-long terminal repeat (non-LTR) retrotransposons are not well understood; the key questions of how the 3′-ends of cDNA copies integrate and how site-specific integration occurs remain unresolved. Integration depends on properties of the endonuclease (EN) domain of retrotransposons. Using the EN domain of the Drosophila R2 retrotransposon as a model for other, closely related non-LTR retrotransposons, we investigated the EN domain and found that it resembles archaeal Holliday-junction resolvases. We suggest that these non-LTR retrotransposons are co-transcribed with the host transcript. Combined with the proposed resolvase activity of the EN domain, this model yields a novel mechanism for site-specific retrotransposition within this class of retrotransposons, with resolution proceeding via a Holliday junction intermediate
The Real Scalar Field Equation for Nariai Black Hole in the 5D Schwarzschild-de Sitter Black String Space
The Nariai black hole, whose two horizons are lying close to each other, is
an extreme and important case in the research of black hole. In this paper we
study the evolution of a massless scalar field scattered around in 5D
Schwarzschild-de Sitter black string space. Using the method shown by Brevik
and Simonsen (2001) we solve the scalar field equation as a boundary value
problem, where real boundary condition is employed. Then with convenient
replacement of the 5D continuous potential by square barrier, the reflection
and transmission coefficients () are obtained. At last, we also compare
the coefficients with usual 4D counterpart.Comment: 10 pages,6 figures.To appear in Int. J. Mod. Phys.
Modern concept of differential diagnosis of colitis: from G.F. Lang to the present day. A review
The aim of the article is to improve the differential diagnosis of specific and nonspecific inflammatory bowel diseases. In Russia, this scientific direction is associated with the name of G.F. Lang, who performed in 1901–1902 the study „On ulcerative inflammation of the large intestine caused by balantidiasis“. The etiology of specific colitis is associated with infection with parasites, bacteria and viruses that cause inflammation of the intestinal wall, diarrhea, often with an admixture of mucus, pus and blood. Specific colitis (SC) may be accompanied by fever, abdominal pain, and tenesmus. Bacterial colitis is commonly caused by Salmonella, Shigella, Escherichia coli, Clostridium difficile, Campylobacter jejuni, Yersinia enterocolitica, and Mycobacterium tuberculosis. Viral colitis is caused by rotavirus, adenovirus, cytomegalovirus, and norovirus. Parasitic colitis can be caused by Entamoeba histolytica and balantidia. In gay people, SC can cause sexually transmitted infections: Neisseria gonorrhoeae, Chlamydia trachomatis, and treponema pallidum, affecting the rectum. Stool microscopy, culture, and endoscopy are used to establish the diagnosis. Stool culture helps in the diagnosis of bacterial colitis in 50% of patients, and endoscopic studies reveal only nonspecific pathological changes. Differential diagnosis of SC should be carried out with immune-inflammatory bowel diseases (ulcerative colitis, Crohn's disease, undifferentiated colitis), radiation colitis and other iatrogenic bowel lesions. The principles of diagnosis and therapy of inflammatory bowel diseases associated with various etiologica
Particle Motion and Electromagnetic Fields of Rotating Compact Gravitating Objects with Gravitomagnetic Charge
The exact solution for the electromagnetic field occuring when the
Kerr-Taub-NUT compact object is immersed (i) in an originally uniform magnetic
field aligned along the axis of axial symmetry (ii) in dipolar magnetic field
generated by current loop has been investigated. Effective potential of motion
of charged test particle around Kerr-Taub-NUT gravitational source immersed in
magnetic field with different values of external magnetic field and NUT
parameter has been also investigated. In both cases presence of NUT parameter
and magnetic field shifts stable circular orbits in the direction of the
central gravitating object. Finally we find analytical solutions of Maxwell
equations in the external background spacetime of a slowly rotating magnetized
NUT star. The star is considered isolated and in vacuum, with monopolar
configuration model for the stellar magnetic field.Comment: 18 pages, 6 figures, new results in section 2 added, section 3 is
revised, 3 references are adde
Is there life inside black holes?
Bound inside rotating or charged black holes, there are stable periodic
planetary orbits, which neither come out nor terminate at the central
singularity. Stable periodic orbits inside black holes exist even for photons.
These bound orbits may be defined as orbits of the third kind, following the
Chandrasekhar classification of particle orbits in the black hole gravitational
field. The existence domain for the third kind orbits is rather spacious, and
thus there is place for life inside supermassive black holes in the galactic
nuclei. Interiors of the supermassive black holes may be inhabited by
civilizations, being invisible from the outside. In principle, one can get
information from the interiors of black holes by observing their white hole
counterparts.Comment: 11 pages, 5 figures; references adde
Efficacy and tolerability of certolizumab pegol in Crohn's disease in clinical practice
Aim. To assess the efficacy and tolerance of certolizumab pegol (CP) in patients with Crohn's disease (CD) treated in the Department of inflammatory bowel diseases of the A.S. Loginov Moscow Clinical Research Center and to determine the predictors of response to therapy. Materials and methods. All patients with CD who had received the treatment of CP were observed prospectively for at least 6 months or until the date of discontinuation of the drug. The effectiveness of the study was assessed response to therapy by the 6th week, maintaining the clinical response (6th and 26th weeks), the dynamics of endoscopic parameters by the 10th and 54th week of therapy, long-term maintenance of remission, healing fistula. Used univariant and multivariate analyses of predictors of response to treatment. Results and discussion. The study included 39 patients: 12 (30.7%) men and 27 (69.3%) female, the average duration of observation was 104 weeks. The interdepartmental range was in the range from 28 to 158 weeks. Clinical improvement occurred in 38 out of 39 (97.4 %) patients with CD. Comparative analysis of response to treatment with CP have bionaive patients previously treated with another inhibitor of TNF-α. In the group of bionaive response to therapy in a month, 6 months and at the end of the observation period occurred at 100.0%, 95.0% and 95.0%, respectively. In the group of patients previously treated with GSI, the response rate was about 94.4 %, 88.9 % and 77.7% week 54 endoscopic response and endoscopic remission was maintained in 46,2% and 30,1% patients, complete healing of the mucosa on the background of maintenance therapy, CP, was preserved in 20.5% of patients with Crohn's disease. In the group of patients with perianal lesions (n=13) complete closure of all fistulas was observed in 5 (38.6 %) patients, partial response was observed in 4 patients (30,7%) patients, in 4 (30.7 %) closure of fistulas occurred. The frequency of adverse events was 0 cases (0.0%). The dose escalation was required in 3 patients (7,7%) patients with CD. Dose escalation in our study required patients with high initial CDAI and previous inefficiencies of the other two inhibitors of TNF-α. Reliable predictors of secondary loss of response and need for dose escalation of the drug has been the continued level of CRP >5 mg/l after 2 weeks initiation of therapy CP and smoking. Conclusion. The obtained results demonstrate the efficacy and tolerability profile of CP appropriate for long-term CD therapy in real clinical practice
Electromagnetic Effects in Superconductors in Gravitational Field
The general relativistic modifications to the resistive state in
superconductors of second type in the presence of a stationary gravitational
field are studied. Some superconducting devices that can measure the
gravitational field by its red-shift effect on the frequency of radiation are
suggested. It has been shown that by varying the orientation of a
superconductor with respect to the earth gravitational field, a corresponding
varying contribution to AC Josephson frequency would be added by gravity. A
magnetic flux (being proportional to angular velocity of rotation )
through a rotating hollow superconducting cylinder with the radial gradient of
temperature is theoretically predicted. The magnetic flux is
assumed to be produced by the azimuthal current arising from Coriolis force
effect on radial thermoelectric current. Finally the magnetic flux through the
superconducting ring with radial heat flow located at the equatorial plane
interior the rotating neutron star is calculated. In particular it has been
shown that nonvanishing magnetic flux will be generated due to the general
relativistic effect of dragging of inertial frames on the thermoelectric
current.Comment: 11 pages 2 figure
Particle motion in the field of a five-dimensional charged black hole
In this paper, we have investigated the geodesics of neutral particles near a
five-dimensional charged black hole using a comparative approach. The effective
potential method is used to determine the location of the horizons and to study
radial and circular trajectories. This also helps us to analyze the stability
of radial and circular orbits. The radius of the innermost stable circular
orbits have also been determined. Contrary to the case of massive particles for
which, the circular orbits may have up to eight possible values of specific
radius, we find that the photons will only have two distinct values for the
specific radii of circular trajectories. Finally we have used the dynamical
systems analysis to determine the critical points and the nature of the
trajectories for the timelike and null geodesics.Comment: 15 pages, accepted for publication in Astrophysics and Space Scienc
Stem Cell Therapy for Perianal Crohn’s Disease
Aim. To compare the effectiveness of the effect of combination therapy (local and systemic administration) with bone marrow mesenchymal stromal cells (MSC), anticlitokine therapy with infliximab (IFX), and antibiotic (AB)/immunosuppressive (IS) therapy on the frequency of healing of simple perianal fistulas in Crohn's disease. Materials and methods. In our study, the 1-st group of patients aged 19 to 58 years (Me-29) (n = 12) received MSCs culture systemically according to the scheme and locally. The 2-nd group of patients with CD (n = 10) from 20 to 68 years old (Me-36) received anticytokine therapy with infliximab (IFX) according to the scheme. The 3-d group of patients with CD (n=14) from 20 to 62 years old (Me-28) received antibiotics (AB) and immunosuppressors (IS). Efficacy was assessed by the index of perianal activity of Crohn's disease (PCDAI) and the frequency of relapses. Results. After 12 weeks among patients of the 1-st group, healing of simple fistulas was noted in 8/12 patients (66.6%), in the 2-nd group in 6/10 (60.0%) In the 3-d group, in 1/14 patients (7.14%). After 6 months in the 1-st group of patients, healing of simple fistulas was preserved in 8/12 (66.6%), in the 2-nd group - in 6/10 (60.0%). In the 3-d group - in 1/14 patients (7.14%). After 12 months in the 1-st group, healing of simple fistulas was preserved in 7/12 (58.3%), in the second group - in 6/10 (60.0%). In the 3-d group - in 2/14 patients (14.3%). After 24 months, among the patients of the 1-st group, fistula closure was maintained in 5/12 patients (41.6%), in the 2-nd group - in 4/10 (40.0%). In the 3-d group - in 0/14 patients (0.0%). Conclusion. Combined cellular and anticytokine therapy of CD with perianal lesions significantly contributes to the more frequent and prolonged closure of simple fistulas, as compared to antibiotics/immunosuppressors, and to a decrease in the frequency of recurrence of the disease