7,159 research outputs found

    The Detection of a 3.5-h Period in the Classical Nova Velorum 1999 (V382 Vel) and the Long Term Behavior of the Nova Light Curve

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    We present CCD photometry, light curve and time series analysis of the classical nova V382 Vel (N Vel 1999). The source was observed for 2 nights in 2000, 21 nights in 2001 and 7 nights in 2002 using clear filters. We report the detection of a distinct period in the light curve of the nova P=0.146126(18) d (3.5 h). The period is evident in all data sets, and we interpret it as the binary period of the system. We also measured an increase in the amplitude modulation of the optical light (in magnitude) by more than 55% from 2000 to 2001 and about 64% from 2001 to 2002. The pulse profiles in 2001 show deviations from a pure sinusoidal shape which progressively become more sinusoidal by 2002. The main cause of the variations in 2001 and 2002 can be explained with the occultation of the accretion disk by the secondary star. We interpret the observed deviations from a pure sinusoidal shape as additional flux resulting from the aspect variations of the irradiated face of the secondary star.Comment: 16 pages and 4 figures, accepted as it stands to be published in the Astronomical Journal (AJ

    Wess-Zumino-Witten model off criticality

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    We study the renormalization group flow properties of the Wess-Zumino-Witten model in the region of couplings between g2=0g^2=0 and g2=4Ï€/kg^2=4\pi/k, by evaluating the two-loop Zamolodchikov's cc-function. We also discuss the region of negative couplings.Comment: 8 page

    Decuplet baryon magnetic moments in a QCD-based quark model beyond quenched approximation

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    We study the decuplet baryon magnetic moments in a QCD-based quark model beyond quenched approximation. Our approach for unquenching the theory is based on the heavy baryon perturbation theory in which the axial couplings for baryon - meson and the meson-meson-photon couplings from the chiral perturbation theory are used together with the QM moment couplings. It also involves the introduction of a form factor characterizing the structure of baryons considered as composite particles. Using the parameters obtained from fitting the octet baryon magnetic moments, we predict the decuplet baryon magnetic moments. The Ω−\Omega^- magnetic moment is found to be in good agreement with experiment: μΩ−\mu_{\Omega^-} is predicted to be −1.97μN-1.97 \mu_N compared to the experimental result of (−-2.02 ±\pm 0.05) μN\mu_N.Comment: 19 pages, 2 figure

    Ferromagnetism below 10 K in Mn doped BiTe

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    Ferromagnetism is observed below 10 K in [Bi0.75Te0.125Mn0.125]Te. This material has the BiTe structure, which is made from the stacking of two Te-Bi-Te-Bi-Te blocks and one Bi-Bi block per unit cell. Crystal structure analysis shows that Mn is localized in the Bi2 blocks, and is accompanied by an equal amount of TeBi anti-site occupancy in the Bi2Te3 blocks. These TeBi anti-site defects greatly enhance the Mn solubility. This is demonstrated by comparison of the [Bi1-xMnx]Te and [Bi1-2xTexMnx]Te series; in the former, the solubility is limited to x = 0.067, while the latter has xmax = 0.125. The magnetism in [Bi1-xMnx]Te changes little with x, while that for [Bi1-2xTexMnx]Te shows a clear variation, leading to ferromagnetism for x > 0.067. Magnetic hysteresis and the anomalous Hall Effect are observed for the ferromagnetic samples.Comment: Accepted for publication in Phys. Rev.

    Feasibility of a dose-intensive CMF regimen with granulocyte colony-stimulating factor as adjuvant therapy in premenopausal patients with node-positive breast cancer

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    Our aim was to study the feasibility of an intensified intravenous CMF (cyclophosphamide, methotrexate and 5-fluorouracil) schedule with the aim to escalate dose intensity (DI). Twenty-three premenopausal breast cancer patients received 6 cycles of adjuvant CMF intravenously on days 1 and 8 every 3 weeks and granulocyte colony-stimulating factor days 9–18. Endpoints were DI and toxicity. Twenty-one out of 23 patients (91%) received the projected total dose and reached ≥ 85% of the projected DI. Compared to ‘classical’ CMF, all patients reached ≥ 111% DI. Nine patients received the planned schedule without delay. Thirteen patients (57%) were treated for infection and four patients (17%) were hospitalized for febrile neutropenia. Twelve patients received red blood cell transfusions (52%). Radiation therapy (n= 6) had no adverse impact on dose intensity or haematological toxicity. This dose-intensified CMF schedule was accompanied by enhanced haematological toxicity with clinical sequelae, namely fever, intravenous antibiotics and red blood cell transfusions, but allows a high dose intensity in a majority of patients. © 2000 Cancer Research Campaig

    Social goals and gains of adolescent bullying and aggression:A meta-analysis

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    There is a long-standing debate on the goals that underlie adolescent socially coercive behaviors, such as bullying, relational aggression, and instrumental aggression. Knowledge about these goals is critical for the development of effective interventions. Bridging evolutionary and social-cognitive perspectives, we propose and substantiate a Social Goals and Gains Model of Adolescent Bullying and Aggression. The model holds that adolescents who hold agentic goals (i.e., getting ahead of others), rather than communal goals (i.e., getting along with others), engage in more bullying and aggression. Engaging in bullying and aggression, in turn, may lead adolescents to gain popularity but lose likeability. To substantiate this model, we meta-analyzed data of 164,143 adolescents (age range: 8–20 years), from 148 independent samples, with Meta-Analytic Structural Equation Modeling (MASEM). Our results both support and refine our model. As hypothesized, adolescents’ agentic goals were associated with higher levels of bullying and aggression. Bullying and aggression, in turn, were associated with higher popularity but lower likeability. However, there was no significant association between adolescents’ communal goals and bullying or aggression. These findings suggest that socially coercive behaviors, such as bullying and aggression, can be fueled by agentic goals and potentially lead to gains in popularity but losses in likeability. This suggests that intervention programs could reduce bullying and aggression by changing the means through which adolescents pursue agentic goals.</p

    Octet Baryon Magnetic Moments in the Chiral Quark Model with Configuration Mixing

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    The Coleman-Glashow sum-rule for magnetic moments is always fulfilled in the chiral quark model, independently of SU(3) symmetry breaking. This is due to the structure of the wave functions, coming from the non-relativistic quark model. Experimentally, the Coleman-Glashow sum-rule is violated by about ten standard deviations. To overcome this problem, two models of wave functions with configuration mixing are studied. One of these models violates the Coleman-Glashow sum-rule to the right degree and also reproduces the octet baryon magnetic moments rather accurately.Comment: 22 pages, RevTe

    Physically meaningful and not so meaningful symmetries in Chern-Simons theory

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    We explicitly show that the Landau gauge supersymmetry of Chern-Simons theory does not have any physical significance. In fact, the difference between an effective action both BRS invariant and Landau supersymmetric and an effective action only BRS invariant is a finite field redefinition. Having established this, we use a BRS invariant regulator that defines CS theory as the large mass limit of topologically massive Yang-Mills theory to discuss the shift k \to k+\cv of the bare Chern-Simons parameter kk in conncection with the Landau supersymmetry. Finally, to convince ourselves that the shift above is not an accident of our regularization method, we comment on the fact that all BRS invariant regulators used as yet yield the same value for the shift.Comment: phyzzx, 21 pages, 2 figures in one PS fil
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