1,073 research outputs found

    X-ray Variability and Period Determinations in the Eclipsing Polar DP Leo

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    An analysis of ROSAT observations for the eclipsing magnetic cataclysmic binary DP Leo provides constraints on the origin, size, temperature, variability and structure of the soft X-ray emission region on the surface of the white dwarf. These data, when combined with prior observations, show a progression of approximately 2 degrees per year in the impact position of the accretion stream onto the white dwarf. One explanation for the observed drift in stream position is that a magnetic activity cycle on the secondary produces orbital period oscillations. These oscillations result in an orbital period which cycles above and below the rotational period of the nearly synchronous white dwarf. The accretion stream and X-ray emission regions are modeled to fit the observational data. A distance to the system is also calculated. [An erroneous value for the cyclotron luminosity, included in an earlier paper version of the preprint, is corrected here.]Comment: uuencoded PostScript file (25 pages) + 8 figures available by anonymous ftp to ftp.astro.psu.edu (in the directory /pub/robinson), to appear in ApJ, PSU preprint 1994-1

    A search for X-ray pulsations from the galactic center

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    Data from the SAS-3 satellite were used in a search for X-ray pulsations from the direction of the galactic center. No periodic X-ray behavior was detected in the frequency interval 0.6 Hz to 0.0006 Hz and energy range 2.5 - 35 keV. For periods less than 60 sec, the upper limit to the amplitude of any pulsation in the 2.5 - 10 keV band is approximately .0017 cts/sq cm/s. This corresponds to a pulsed fraction of approximately 1.3 percent of the total GCX flux. Somewhat higher limits apply for longer periods and for energies greater than 10 keV

    Adipose-derived stem cells: true or false? A different point of view

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    A propeller flap for single-stage nose reconstruction in selected patients: supratrochlear artery axial propeller flap

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    The paramedian forehead flap is the gold standard technique for nose reconstruction. It requires two different surgical operations which prolonged the postoperative dressing and care. We present our 5-year experience with a propeller flap based on the supratrochlear artery, which allows one-stage transfer of the forehead skin to the nose without the need for pedicle division. This technique is indicated in a selected group of patients who are not suitable for multiple-stage reconstructions because they have concurrent medical conditions, reduced mobility, or live far away from specialized medical centers. We have renamed this procedure as supratrochlear artery axial propeller flap, from the acronym STAAP flap, to stress the axial, well known and constant, vascularization of the flap. In the past 5 years, we have been performing 25 STAAP flaps; full-thickness nasal reconstruction was performed in 11 cases. The patients were 16 males and 9 females, with a mean age of 79.5 years. All patients had multiple comorbidities. Complete flap survival was observed in 23 cases and healing was complete in 7 days. In two cases, there was a partial distal necrosis of the flap treated conservatively. Cosmetic results were good and the patient's satisfaction was significant. These results indicate that the STAAP flap is a reliable and useful technique in selected cases, as old or noncompliant patients who benefit from a one-stage technique of nose reconstructio

    Prevalência relevante de Mycoplasma hominis e sorogrupos de Ureaplasma urealyticum em homens infectados pelo HIV-1 sem sintomas de uretrite

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    M. hominis and U. urealyticum are the better-known mycoplasma species pathogenic to the human genitourinary tract, causing mainly urethritis, bacterial vaginosis and pregnancy complications. In HIV-infected patients, the prevalence and role of these species is still not well known. The aim of this work was to determinate the prevalence of these species in this group of male patients (HIV group), in comparison to a group of men with clinical symptoms of urethritis (STD group). M. hominis was isolated from 7.5% patients (8/106) and U. urealyticum from 18.9% patients (20/106) from the HIV group, being among these 62.5% and 85% in significant concentrations, respectively. In the STD group these rates were 0.9% (1/110) for M. hominis and 13.6% (15/110) for U. urealyticum, being 100% and 93.3% in significant concentrations, respectively. We could demonstrate infection rates by these mycoplasma species in the HIV group as high as the one found in the STD one, what may indicate the occurrence of opportunistic infections in our population. This fact is discussed here because in immunosuppressed patients, specially M. hominis has been reported causing severe infections, even systemically.M. hominis e U. urealyticum s├úo as esp├ęcies de micoplasmas mais conhecidas como patog├¬nicas para o trato geniturin├írio humano, causando principalmente uretrite, vaginose bacteriana e complica├ž├Áes da gravidez. Em pacientes infectados pelo HIV, a preval├¬ncia e o papel destas esp├ęcies ainda n├úo est├í bem estabelecido. O objetivo do presente estudo foi comparar a preval├¬ncia das esp├ęcies acima referidas na uretra de pacientes masculinos portadores do v├şrus HIV (Grupo HIV) com a preval├¬ncia das mesmas entre homens n├úo portadores do HIV mas com sintomas de uretrite (grupo DST). No grupo HIV, M. hominis foi isolado de 7,5% pacientes (8/106) e U. urealyticum de 18,9% pacientes (20/106) em concentra├ž├Áes significativas de 62,5% e 85% respectivamente. No grupo DST estas taxas foram 0,9% (1/110) para M. hominis e 13,6% (15/110) para U. urealyticum, sendo 100% e 93,3% em concentra├ž├Áes significantes, respectivamente. P├┤de-se demonstrar que no grupo HIV as taxas de infec├ž├úo por estes micoplasmas foram t├úo elevadas quanto as observadas no grupo DST. Tais achados podem indicar a ocorr├¬ncia de infec├ž├úo oportunista, o que, em pacientes imunocomprometidos representa risco de desenvolvimento de infec├ž├Áes sist├¬micas

    Skewed Differentiation of Circulating V╬│9V╬┤2 T Lymphocytes in Melanoma and Impact on Clinical Outcome

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    Objective The aim of this study was to evaluate over time circulating ╬│╬┤ T lymphocytes in melanoma patients in terms of frequency, effector functions, and relationship with clinical stage and evolution, by comparing preoperative values to those obtained at a mean follow-up of 36 months or in the event of recurrence or disease progression, and to those of healthy controls. Also, we correlated the presence of tumor-infiltrating ╬│╬┤ T lymphocytes with clinical evolution of melanoma. Results Mean frequencies of circulating ╬│╬┤ T cells before and after melanoma removal were very similar and comparable to healthy subjects, but patients who progressed to stage III or IV showed a significantly decreased frequency of circulating V╬│9V╬┤2 T cells. The distribution of V╬│9V╬┤2 memory and effector subsets was similar in healthy subjects and melanoma patients at diagnosis, but circulating ╬│╬┤ T cells of patients after melanoma removal had a skewed terminally-differentiated effector memory phenotype. Highly suggestive of progressive differentiation toward a cytotoxic phenotype, V╬│9V╬┤2T cells from patients at follow up had increased cytotoxic potential and limited cytokine production capability, while the opposite pattern was detected in V╬│9V╬┤2T cells from patients before melanoma removal. Conclusions Follow-up data also showed that tumor infiltrating ╬│╬┤ T cells were significantly associated with lower mortality and relapse rates, suggesting that they may serve as a prognostic biomarker, for human melanom
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