A non-linear resonance model for the black hole and neutron star QPOs: theory supported by observations

Kilohertz Quasi-Periodic Oscillations (QPOs) have been detected in many accreting X-ray binaries. It has been suggested that the highest QPO frequencies observed in the modulation of the X-ray flux reflect a non-linear resonance between two modes of accreting disk oscillation. This hypothesis implies certain very general predictions, several of which have been borne out by observations. Some of these follow from properties of non-linear oscillators, while the others are specific to oscillations of fluid in strong gravity. A 3:2 resonant ratio of frequencies can be clearly recognized in the black-hole as well as in the neutron-star QPO data.Comment: 8 pages, 8 figures, to appear in Proceedings of the Albert Einstein Century International Conferenc

Effects of Two Types of Creatine Feeding and Doxorubicin on Skeletal Muscle Apoptotic Markers

Doxorubicin (Dox) is a widely used anthracycline antibiotic used to treat a number of hematological and solid tumor cancers. Dosage however, is limited due to its toxic effects in healthy tissues. Negative consequences include myotoxicity in skeletal muscle, which may limit mobility and activities of daily living. Doxorubicin increases the formation of reactive oxygen species, which triggers apoptosis in the tumor and healthy tissue. Skeletal muscle undergoes apoptosis in response to Dox treatment, via the activation of the cleaved caspase-3 and its downstream target, poly(ADP-ribose) polymerase. Creatine monohydrate (Cr), a naturally occurring chemical, when taken exogenously, can improve athletic performance. Recently, it has been shown that Cr can positively impact several diseases and act as a antioxidant, capable of scavenging free radicals and reducing apoptosis. Purpose: To determine the effect of two types of Cr feeding and Dox administration on skeletal muscle apoptotic proteins at two separate time points. Methods: Ten week old male Sprague-Dawley rats were randomly assigned to one of six groups: control + saline (Con-Sal, n=10), control + doxorubicin (Con-Dox, n=10), creatine 1 + saline (C1-Sal, n=10), creatine 1 + doxorubicin (C1-Dox, n=10), creatine 2 + saline (C2-Sal, n=10), creatine 2 + doxorubicin (C2-Dox, n=10). Animals were fed for four weeks and were injected with a bolus 15 mg/kg i.p. injection of Dox or Sal and sacrificed either 1-day or 3-days post injection. Post injection, the extensor digitorum longus (EDL), soleus (SOL), and diaphragm (DIA) were excised and Western blotting for expression of cleaved PARP, caspase-3, and cleaved caspase-3 was conducted. Creatine concentration was also analyzed using a commercially available assay kit. Results: A main drug effect was observed, with increased levels of apoptosis observed in the 1-day EDL, SOL, and in the 3-day EDL. Equally, a main drug effect was observed, with decreased caspase-3 levels in the 3-day SOL, and cleaved PARP levels in the 3-day DIA. There was a diet effect, with increased cleaved PARP levels in the 1-day EDL, SOL, and cleaved caspase-3 levels in the 3-day EDL. An equal diet effect was detected, with decreased caspase-3 levels in the 1-day EDL and cleaved caspase-3 levels in the 1-day SOL and DIA. The 1-day SOL had lower creatine concentration with Dox administration and the 3-day EDL had decreased Cr concentrations with both Dox administration and Cr feeding. Conclusion: Doxorubicin had the largest impact on apoptosis in the EDL, suggesting Dox’s effects on apoptosis may differ between tissue. Creatine concentration in the EDL was lower in animals receiving Dox, and this was not observed in the DIA, supporting the idea that Dox toxicity may differ between tissue

Polynomial loss of memory for maps of the interval with a neutral fixed point

We give an example of a sequential dynamical system consisting of intermittent-type maps which exhibits loss of memory with a polynomial rate of decay. A uniform bound holds for the upper rate of memory loss. The maps may be chosen in any sequence, and the bound holds for all compositions.Comment: 16 page

Manipulation of Light with Magneto-optic Stripe Domain Films

Magnetic diffraction grating materials, being developed to provide a simple means of deflecting light in a two dimensional, solid state fashion are discussed. The most promising material, for several applications, appears to be bismuth substituted iron garnet films in epitaxial form. Calculations indicate that deflection efficiency greater than 60% is possible in the near infrared region of the spectrum. Within the field of view of the deflector, measurements predict that 105 resolvable spots can be expected. Applications include: (1) general purpose deflection of free laser light, (2) image processing of extended sources such as transparencies, (3) programmable lensing, and (4) fiber optic matrix switching

Microstructure of Extruded Mixtures of Cereals and Oil Seed Processing Residues

The utilization of valuable by-products of seed processing residues as coextrusion materials was investigated. By mixing sunflower, pumpkin, corn or rice germ presscake with cereals (wheat, corn, rice), the good protein quality of the former group might improve the biological value of the resulting coextrudates. The microstructure of such coextruded products was analysed with reference to their chemical compositions, nutritional characteristics and functional properties. As seed processing residue was increased, the microstructure of the products became more compact and uniform and the air/solids ratio decreased considerable. The results showed that the highest acceptable concentration of the additive was not more than 20-40% for the applied high temperature short-time procedure

The Electromagnetic Self-Energy Contribution to M_p - M_n and the Isovector Nucleon Magnetic Polarizability

We update the determination of the isovector nucleon electromagnetic self-energy, valid to leading order in QED. A technical oversight in the literature concerning the elastic contribution to Cottingham's formula is corrected and modern knowledge of the structure functions is used to precisely determine the inelastic contribution. We find \delta M_{p-n}^\gamma = 1.30(03)(47) MeV. The largest uncertainty arises from a subtraction term required in the dispersive analysis, which can be related to the isovector magnetic polarizability. With plausible model assumptions, we can combine our calculation with additional input from lattice QCD to constrain this polarizability as: \beta_{p-n} = -0.87(85) x 10^{-4} fm^3.Comment: 5 pages, version accepted for publication in PR

Black hole spin inferred from 3:2 epicyclic resonance model of high-frequency quasi-periodic oscillations

Estimations of black hole spin in the three Galactic microquasars GRS 1915+105, GRO J1655-40, and XTE J1550-564 have been carried out based on spectral and timing X-ray measurements and various theoretical concepts. Among others, a non-linear resonance between axisymmetric epicyclic oscillation modes of an accretion disc around a Kerr black hole has been considered as a model for the observed high-frequency quasi-periodic oscillations (HF QPOs). Estimates of spin predicted by this model have been derived based on the geodesic approximation of the accreted fluid motion. Here we assume accretion flow described by the model of a pressure-supported torus and carry out related corrections to the mass-spin estimates. We find that for dimensionless black hole spin a<0.9, the resonant eigenfrequencies are very close to those calculated for the geodesic motion. Their values slightly grow with increasing torus thickness. These findings agree well with results of a previous study carried out in the pseudo-Newtonian approximation. The situation becomes different for a>0.9, in which case the resonant eigenfrequencies rapidly decrease as the torus thickness increases. We conclude that the assumed non-geodesic effects shift the lower limit of the spin, implied for the three microquasars by the epicyclic model and independently measured masses, from a~0.7 to a~0.6. Their consideration furthermore confirms compatibility of the model with the rapid spin of GRS 1915+105 and provides highly testable predictions of the QPO frequencies. Individual sources with a moderate spin (a<0.9) should exhibit a smaller spread of the measured 3:2 QPO frequencies than sources with a near-extreme spin (a~1). This should be further examined using the large amount of high-resolution data expected to become available with the next generation of X-ray instruments, such as the proposed Large Observatory for X-ray Timing (LOFT).Comment: 6 pages, 4 figures, accepted by Astronomy & Astrophysic

Full QED+QCD Low-Energy Constants through Reweighting

The effect of sea quark electromagnetic charge on meson masses is investigated, and first results for full QED+QCD low-energy constants are presented. The electromagnetic charge for sea quarks is incorporated in quenched QED+full QCD lattice simulations by a reweighting method. The reweighting factor, which connects quenched and unquenched QED, is estimated using a stochastic method on 2+1 flavor dynamical domain-wall quark ensembles.Comment: 5 pages, 9 figures, REVTeX 4.1, v2: published versio

Response to combination therapy with interferon alfa-2a and ribavirin in chronic hepatitis C according to a TNF-alpha promoter polymorphism

Background. Tumor necrosis factor-alpha (TNF-alpha) is involved in the pathogenesis of chronic active hepatitis C. Polymorphisms in the promoter region of the TNF-alpha gene can alter the TNF-alpha expression and modify the host immune response. The present study aimed at the correlation of the G308A TNF-alpha polymorphism with the response to antiviral combination therapy in chronic hepatitis C. Patients and Methods: 62 patients with HCV and 119 healthy unrelated controls were genotyped for the G308A TNF-alpha promoter polymorphism. The patients received 3 x 3 million units of interferon alfa-2a and 1,0001,200 mg ribavirin daily according to their body weight. A response was defined as absence of HCV-RNA and normalization of S-ALT after 6 months of combination therapy. Results:With respect to the allele and genotype frequency, a significant difference was not observed between controls and patients with chronic hepatitis C. Furthermore, such a difference was also not observed if responders and non-responders to antiviral therapy were compared. Conclusions: The promoter polymorphism of the TNF-alpha gene investigated herein is equally distributed in healthy individuals and patients with hepatitis C and does not seem to predict the response to therapy with interferon alfa-2a and ribavirin. Copyright (C) 2003 S. Karger AG, Basel