65,588 research outputs found
On the absorption of X-ray bright broad absorption line quasars
No full textContext. Most X-ray studies of broad absorption line quasars (BALQSOs) found significant (NH ∼ 1022−24 cm−2) intrinsic column densities of gas absorbing an underlying typical power-law continuum emission, in agreement with expectations from radiatively driven accretion disk wind models. However, direct spectral analysis was performed only on a limited number of bright sources. Aims. We investigate the X-ray emission of a large number of BALQSOs at medium to high redshift (0.8 <∼ z <∼ 3.7) with the best data available to date.
Methods. We drew a large BALQSO sample from the cross-correlation of SDSS DR5 and 2XMM catalogs to perform moderate- quality X-ray spectral and hardness ratio analysis and X-ray/optical photometry. We compare our results with previous studies of BALQSOs and theoretical disk wind model expectations.
Results. No or little intrinsic X-ray neutral absorption is found for one third of the spectroscopically analyzed BALQSO sample (NH < 4 × 1021 cm−2 at 90% confidence level), and lower than typical X-ray absorption is found in the remaining sources (⟨NH⟩ ∼ 5 × 1022 cm−2) even including the faintest sources analyzed through hardness ratio analysis. The mean photon index is Γ ∼ 1.9, with no significant evolution with redshift. The optical/X-ray spectral indices αox are typical of radio-quiet broad line AGN, in contrast with the known (from previous X-ray studies) “soft X-ray weakness” of BALQSOs and in agreement with the lack of X-ray absorption. We found the low-absorption index (AI) subsample to host the lowest X-ray absorbing column densities of the entire sample. Conclusions. X-ray selected BALQSOs show lower X-ray absorption than purely optically selected ones, and soft X-ray weakness does not hold for any of them. Their outflows may be launched by different mechanisms than classical soft X-ray weak BALQSOs or they may be the tail of the already known population seen along a different line of sight, in both cases expanding the observational parameter space for their search and investigation
Disinfection of indoor air for the inactivation of SARS-CoV-2: a review of the effectiveness of UV-C technology and gaps in research
No full textCoronavirus disease (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In indoor environments, a structured strategy is needed to reduce the risk of infection. In addition to maintaining proper ventilation and wearing face masks, the development of effective technologies for limiting the transmission of SARS-CoV-2 through infectious respiratory particles (IRPs) has been studied. UV-C devices have already proved effective against other types of microorganisms and have also been investigated for their potential in inactivating SARS-CoV-2. This work aims to review and discuss these findings while also presenting recommendations for future research. Based on the available data, UV-C proved to be effective in the inactivation of airborne SARS-CoV-2 or its surrogates. The main gaps in this research have also been highlighted, and some outlooks for future studies have been suggested. In some studies, the use of surrogates with higher susceptibility to UV-C than airborne SARS-CoV-2 or the consideration of total bacterial counts alone may have led to misleading results. The question “how much variables affect the inactivation rate of airborne SARS-CoV-2 by UV-C in indoor environments?” is still unsolved, considering that the number of studies on the inactivation of this virus in real indoor environments is quite limited. The outcomes of this study can be useful for the scientific community, the technical stakeholders (e.g., managers in the healthcare and transport sectors), and the common people, providing important information about the performance of these technologies to improve the quality of air in indoor environments
Endometrioma excision and ovarian reserve : a dangerous relation
No full textEndometrioma is one of the most frequent pathologies in gynecologic surgery. Laparoscopic cyst excision is considered the best treatment in terms of lower recurrence and improved fertility. However, it was recently questioned whether the excision of the endometrioma could decrease the function of the operated ovary and if it could affect the subsequent fertility. Even if a consistent amount of ovarian tissue is unintentionally removed together with the capsule of the cyst, resulting in does not show the follicular pattern observed in working ovaries. Currently, no definitive data clarify whether the damage to the ovarian reserve, observed in patient with endometrioma, is related to the surgical procedure, to the previous presence of the cyst, or both. Electrosurgial coagulation during hemostasis could play an important role in terms of damage to ovarian stroma and vascularization. Particular attention must be paid in presence of bilateral endometriotic cysts. In fact, an increase in premature ovarian failure rate was reported when both the ovaries are involved in surgery. Incase of assisted reproductive techniques, no clear evidence indicates which is the best approach for concomitant endometriotic cyst. On the base of these considerations endometriomas Should be treated only in case of pain, infertility, and in asymptomatic patients if the cyst diameter is greater than 4 c
Options for primary chemotherapy in advanced ovarian cancer: the European perspective
No full textPrimary chemotherapy for ovarian cancer has evolved over the past 30 years from the use of single alkylating agent to several combination regimens. Treatment strategies, however, vary greatly both nationally and internationally, since no firm results can be derived from available data. Five questions can be identified: (1) Should primary chemotherapy consist of single agent or combination? (2) Should it include doxorubicin? (3) Is cisplatin or carboplatin preferred? (4) Which is the role of cisplatin dose intensity? (5) Should it include taxol? Available data from the European experience are discussed. Final considerations include: (1) Platinum combinations are more effective than single agent platinum when this drug is used at the same dose (now considered lower than current standard). (2) CAP offers a survival benefit of 7% at 6 years compared to CP. However, in most trials dose intensity was higher in CAP than in CP. (3) Cisplatin and carboplatin are equally effective. (4) There is no survival benefit when doubling the dose intensity of cisplatin over 25 mg/m 2/week. (5) A confirmatory study wig help define the contribution of Taxol in the first- line treatment of ovarian cancer, when administered at 175 mg/m 2 over a 3- hr infusion in association with cisplatin
Overview of laparoscopic techniques for endometriosis surgery
No full textThe aim of this chapter is to overview the surgical techniques and modalities employed in the treatment of advanced endometriosis, particularly ovarian endometriosis, deep endometriosis, and recurrent endometriosis
Surgical treatment by laparoscopy : overview of laparoscopic techniques for endometriosis surgery
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