Time properties of the the rho-class burst of the microquasar GRS 1915+105 observed with BeppoSAX in April 1999

We present a temporal analysis of a BeppoSAX observation of GRS 1915+105 performed on April 13, 1999 when the source was in the rho class, which is characterised by quasi-regular bursting activity. The aim of the present work is to confirm and extend the validity of the results obtained with a BeppoSAX observation performed on October 2000 on the recurrence time of the burst and on the hard X-ray delay. We divided the entire data set into several series, each corresponding to a satellite orbit, and performed the Fourier and wavelet analysis and the limit cycle mapping technique using the count rate and the average energy as independent variables. We found that the count rates correlate with the recurrence time of bursts and with hard X-ray delay, confirming the results previously obtained. In this observation, however, the recurrence times are distributed along two parallel branches with a constant difference of 5.2+/-0.5 s.Comment: Accepted for publication in Section 7. Stellar structure and evolution of Astronomy and Astrophysic

Long-term disease-free survival of patients with radically resected thymomas: relevance of cell-cycle protein expression

BACKGROUND. Despite radical Surgical resection, thymomas often recur. The objective of the current retrospective Study was to investigate the prognostic relevance of the expression of cell-cycle proteins in these neoplasms to formulate a possible therapeutic Surveillance strategy for the prevention of recurrence. METHODS. The authors retrospectively reviewed the main clinicopathologic factors, including the World Health Organization (WHO) classification, of patients with thymoma who had undergone radical surgical resection. Specimens were studied using immunohistochemistry and the expression of cell-cycle proteins (i.e., p21, p27, and p53) was assessed. Univariate and multivariate analysis of predicting survival prognostic factors were performed. RESULTS. The authors analyzed 88 patients with thymoma who underwent radical surgical resection at the study institution. According to the Masaoka staging system, 41 patients had Stage I disease, 31 patients had Stage II disease, and 16 patients had Stage III disease. There were 24 tumor recurrences (27.3%), 4 of which were local, 16 of which were distant intrathoracic, and 4 of which were extrathoracic. The second radical resection provided a disease-free Survival rate that was similar to the first. Only Masaoka stage (P=0.001), WHO classification (P=0.001), high expression of p53 (P=0.03), and low expression of p21 (P=0.02) and p27 (P=0.001) were found to he correlated with a reduced disease-free survival. Low p27 expression was found to be the most significant predictive factor of a short disease-free Survival (P=0.001), especially when associated with low p21 expression and high p53 expression (P=0.0001). CONCLUSIONS. Long-term disease-free survival in thymoma patients treated with radical surgical resection Was found to be correlated with Masaoka stage, WHO classification, and expression of cell-cycle proteins, with the latter found to be the most significant predictive factor. Functional cooperation between cell-cycle proteins might constitute another level of regulation in tumor growth. More careful surveillance should be adopted whenever there is negative cell-cycle protein expression. (c) 2005 American Cancer Society

Temporal features of LS I +61∘^{\circ}303 in hard X-rays from the Swift/BAT survey data

We study the long-term spectral and timing behaviour of LS I +61$^{\circ}$303 in hard X-rays (15--150 keV) using $\sim$10 years of survey data from the $Swift$ Burst Alert Telescope (BAT) monitor. We focus on the detection of long periodicities known to be present in this source in multiple wavelengths. We clearly detect three periods: the shorter one at 26.48 days is compatible with the orbital period of the system; the second, longer, periodicity at 26.93 days, is detected for the first time in X-rays and its value is consistent with an analogous temporal feature recently detected in the radio and in the gamma-ray waveband, and we associate it with a modulation caused by a precessing jet in this system. Finally, we find also evidence of the long-term periodicity at $\sim$1667 d, that results compatible with a beat frequency of the two close, and shorter, periodicities. We discuss our results in the context of the multi-band behaviour of the physical processes of this source.Comment: 5 pages, 8 figures. Published in MNRA

Swift-XRT 6-year monitoring of the ultraluminous X-ray source M33-X8

The long term evolution of ULX with their spectral and luminosity variations in time give important clues on the nature of ULX and on the accretion process that powers them. We report here the results of a Swift-XRT 6-year monitoring campaign of the closest example of a persistent ULX, M33 X-8, that extends to 16 years the monitoring of this source in the soft X-rays. The luminosity of this source is a few 10^39 erg/s, marking the faint end of the ULX luminosity function. We analysed the set of 15 observations collected during the Swift monitoring. We searched for differences in the spectral parameters at different observing epochs, adopting several models commonly used to fit the X-ray spectra of ULX. The source exhibits flux variations of the order of 30%. No significant spectral variations are observed along the monitoring. The average 0.5-10 keV spectrum can be well described by a thermal model, either in the form of a slim disk, or as a combination of a Comptonized corona and a standard accretion disk.Comment: 6 pages, 4 figures, 2 tables. Paper published in A&

A Faddeev Calculation for Pentaquark Θ+\Theta^+ in Diquark Picture with Nambu-Jona-Lasinio Type Interaction

A Bethe-Salpeter-Faddeev (BSF) calculation is performed for the pentaquark $\Theta^+$ in the diquark picture of Jaffe and Wilczek in which $\Theta^+$ is a diquark-diquark-${\bar s}$ three-body system. Nambu-Jona-Lasinio (NJL) model is used to calculate the lowest order diagrams in the two-body scatterings of ${\bar s}D$ and $D D$. With the use of coupling constants determined from the meson sector, we find that ${\bar s}D$ interaction is attractive while $DD$ interaction is repulsive, and there is no bound $\frac 12^+$ pentaquark state. A bound pentaquark $\Theta^+$ can only be obtained with unphysically strong vector mesonic coupling constants.Comment: 4 pages, 4 figure

Inferring networks from high-dimensional data with mixed variables

We present two methodologies to deal with high-dimensional data with mixed variables, the strongly decomposable graphical model and the regression-type graphical model. The first model is used to infer conditional independence graphs. The latter model is applied to compute the relative importance or contribution of each predictor to the response variables. Recently, penalized likelihood approaches have also been proposed to estimate graph structures. In a simulation study, we compare the performance of the strongly decomposable graphical model and the graphical lasso in terms of graph recovering. Five different graph structures are used to simulate the data: the banded graph, the cluster graph, the random graph, the hub graph and the scale-free graph. We assume the graphs are sparse. Our finding, in the simulation study, is that the strongly decomposable graphical model shows, generally, comparable or better performance both in low and high-dimensional case. Finally, we show an application on mixed data

Lyapunov functions for a non-linear model of the X-ray bursting of the microquasar GRS 1915+105

This paper introduces a biparametric family of Lyapunov functions for a non-linear mathematical model based on the FitzHugh-Nagumo equations able to reproduce some main features of the X-ray bursting behaviour exhibited by the microquasar GRS 1915+105. These functions are useful to investigate the properties of equilibrium points and allow us to demonstrate a theorem on the global stability. The transition between bursting and stable behaviour is also analyzed.Comment: Published on International Journal of Non-Linear Mechanics, vol. 88, pp. 142-14

Feasibility and results of awake thoracoscopic resection of solitary pulmonary nodules

BACKGROUND: General anesthesia with single-lung ventilation is considered mandatory for thoracoscopic pulmonary resection. We assessed in a randomized study the feasibility and results of awake thoracoscopic resection of solitary pulmonary nodules. METHODS: Between March 2001 and February 2003, 60 patients were randomized into two 30-patients arms: a general anesthesia arm entailing double-lumen intubation and thoracic epidural anesthesia (control group); and an awake arm entailing sole thoracic epidural anesthesia at T4-T5 (awake group). Anesthesia time; operative time; global operating room time; patient satisfaction with the anesthesia and technical feasibility scored into 4 grades (from 1 = poor to 4 = excellent); visual analog pain score (VAS), nursing care (number of patient calls per day), 24 hours changes in arterial oxygenation (DeltaPaO2), and hospital stay were assessed. RESULTS: There was no mortality. There was no difference in technical feasibility between the groups although 2 patients in the awake group required conversion to thoracotomy due to severe adhesions. Other 2 patients in each group required conversion due to unexpected lung cancer requiring lobectomy. Comparisons of awake versus control group results showed that in the awake group, anesthesia satisfaction score was greater (4 vs 3, p = 0.04), whereas DeltaPaO2 (-3 mm Hg vs -6.5 mm Hg, p = 0.002); nursing care (2.5 calls per day vs 4 calls per day, p = 0.0001), and hospital stay (2 days vs 3 days, p = 0.02) were significantly reduced. CONCLUSIONS: In our study, awake thoracoscopic resection of solitary pulmonary nodules proved safely feasible. It resulted in better patient satisfaction, less nursing care and shorter in-hospital stay than procedures performed under general anesthesi

Using R via PHP for Teaching Purposes: R-php

This paper deals with the R-php statistical software, that is an environment for statistical analysis, freely accessible and attainable through the World Wide Web, based on R. Indeed, this software uses, as “engine” for statistical analyses, R via PHP and its design has been inspired by a paper of de Leeuw (1997). R-php is based on two modules: a base module and a point-and-click module. R-php base allows the simple editing of R code in a form. R-php point-and-click allows some statistical analyses by means of a graphical user interface (GUI): then, to use this module it is not necessary for the user to know the R environment, but all the allowed analyses can be performed by using the computer mouse. We think that this tool could be particularly useful for teaching purposes: one possible use could be in a University computer laboratory to permit a smooth approach of students to R