The X-ray emission of the Crab-like pulsar PSR J0537-6910

In this paper we present some preliminary result on the spectral and timing analysis of the X-ray pulsed emission from the 16 ms pulsar PSR J0537-6910 in the energy range 0.1--30 keV, based on archival BeppoSAX and RossiXTE observations. This pulsar, discovered by Marshall et al.(1998) in the LMC field with RXTE, is the fastest spinning pulsar associated with a supernova remnant. It is characterized by strong glitch activity with the highest rate of all known Crab-like system.Comment: 4 pages, 2 figures. Contribution to the proceedings of "The Restless High-Energy Universe", Amsterdam, May 5-8, 2003. Editors: E.P.J. van den Heuvel, J.J.M. in't Zand, R.A.M.J. Wijer

The optical to gamma-ray emission of the Crab pulsar: a multicomponent model

We present a multicomponent model to explain the features of the pulsed emission and spectrum of the Crab Pulsar, on the basis of X and gamma-ray observations obtained with BeppoSAX, INTEGRAL and CGRO. This model explains the evolution of the pulse shape and of the phase-resolved spectra, ranging from the optical/UV to the GeV energy band, on the assumption that the observed emission is due to more components. The first component, C_O, is assumed to have the pulsed double-peaked profile observed at the optical frequencies, while the second component, C_X, is dominant in the interpeak and second peak phase regions. The spectra of these components are modelled with log-parabolic laws and their spectral energy distributions have peak energies at 12.2 and 178 keV, respectively. To explain the properties of the pulsed emission in the MeV-GeV band, we introduce two more components, C_Ogamma and C_Xgamma, with phase distributions similar to those of C_O and C_X and log-parabolic spectra with the same curvature but peak energies at about 300 MeV and 2 GeV. This multicomponent model is able to reproduce both the broadband phase-resolved spectral behaviour and the changes of the pulse shape with energy. We also propose some possible physical interpretations in which C_O and C_X are emitted by secondary pairs via a synchrotron mechanism while C_Ogamma and C_Xgamma can originate either from Compton scattered or primary curvature photons.Comment: 14 pages, 16 figures; accepted by Astronomy and Astrophysic

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

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&

Transxiphoid hand-assisted videothoracoscopic surgery

BACKGROUND: We have performed transxiphoid hand-assisted videothoracoscopy since 1995 to allow manual palpation in bilateral lung metastasectomy. This approach was extended to other thoracoscopic procedures requiring a handport. No extensive report about early and late results has yet been published. METHODS: We retrospectively reviewed the first 100 consecutive patients undergoing transxiphoid hand-assisted videothoracoscopy. Acute and chronic postoperative pain, respiratory function, patient's satisfaction score (1 to 5), quality of life (Short Form-36), and survival rate were evaluated. RESULTS: Seventy-four patients had lung metastases, 5 had primary lung cancers, 16 had benign nodules, and 5 had Morgani's hernia. Five patients needed conversion to thoracotomy, whereas 7 successfully underwent a second transxiphoid operation. Sixty-five metastatic patients were bilaterally explored, 44 were without radiologic evidence of contralateral lesions, discovering 23 occult metastases and 10 patients with occult contralateral disease. A total of 207 minimal resections and 11 lobectomies were performed. Mean operative time was 103 +/- 35 minutes. We had no intraoperative mortality or major complications. Thirty-day postoperative morbidity documented arrhythmia (n = 4) and acute pneumonia (n = 4). Visual Analogue Scale pain, C-reactive protein, fibrinogen, and serum interleukin-6, -8, and -10 normalized within 72 hours. Respiratory function and most of the Short Form-36 domains recovered within 3 months. Six-month mean patient satisfaction score was 4.0 +/- 0.8. Three- and 5-year survival rates for metastatic patients were 52% and 43%, respectively. Mean disease-free interval was 12 +/- 5.8 months. CONCLUSIONS: Transxiphoid hand-assisted videothoracoscopy proved a good alternative to conventional approaches, and provided rapid recovery without affecting the survival rate in those patients with metastatic lesions. We recommend it whenever a handport during video-assisted procedure is required

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