206 research outputs found
Spatially resolved Fe K spectroscopy of NGC 4945
We present the imaging and spectroscopic analysis of the combined Chandra
ACIS-S observations of the Compton-thick Seyfert 2 galaxy NGC 4945. We
performed a spatially-resolved spectroscopy of the circumnuclear environment of
the source, picturing the innermost 200 parsecs around the highly absorbed
nucleus. The additional 200 ks ACIS-S data with respect to the previous
campaign allowed us to map with even greater detail the central structure of
this source and to discover an enhanced iron emission in the innermost nuclear
region, with respect to the associated Compton reflection continuum. We
revealed that the Equivalent Width of the iron K line is spatially
variable (ranging from 0.5 to 3 keV), on scales of tens of parsecs, likely due
to the ionization state and orientation effects of the reprocessing material,
with respect to the central X-ray illuminating source. A clump of highly
ionized Fe XXV He- is also detected, 40 parsecs east to the nucleus.
When observations taken years apart are considered, the central unresolved
reflected emission is found to remain constant.Comment: 10 pages, 6 figures, 4 tables, accepted for publication in MNRA
Abdominal cross-sectional imaging of the associating liver partition and portal vein ligation for staged hepatectomy procedure
Associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) is a recently introduced technique aimed to perform two-stage hepatectomy in patients with a variety of primary or secondary neoplastic lesions. ALPSS is based on a preliminary liver resection associated with ligation of the portal branch directed to the diseased hemiliver (DH), followed by hepatectomy after an interval of time in which the future liver remnant (FLR) hypertrophied adequately (partly because of preserved arterialization of the DH). Multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI) play a pivotal role in patients\u2019 selection and FLR assessment before and after the procedure, as well as in monitoring early and late complications, as we aim to review in this paper. Moreover, we illustrate main abdominal MDCT and MRI findings related to ALPPS
Quasars as Standard Candles IV. Analysis of the X-ray and UV indicators of the disc-corona relation
Context: A non-linear relation between quasar monochromatic luminosities at
2500A and 2 keV holds at all observed redshifts and luminosities, and it has
been used to derive quasar distances and to build a Hubble Diagram of quasars.
The choice of the X-ray and UV indicators has so far been somewhat arbitrary,
and has typically relied on photometric data. Aims: We want to determine the
X-ray and UV proxies that provide the smallest dispersion of the relation, in
order to obtain more precise distance estimates, and to confirm the reliability
of the X-ray to UV relation as a distance indicator. Methods: We performed a
complete UV spectroscopic analysis of a sample of 1800 quasars with SDSS
optical spectra and XMM- Newton X-ray serendipitous observations. In the
X-rays, we analysed the spectra of all the sample objects at redshift z 1.9,
while we relied on photometric measurements at lower redshifts. As done in
previous studies, we analysed the relation in small redshift bins, using fluxes
instead of luminosities. Results: We show that the monochromatic fluxes at 1
keV and 2500A are, respectively, the best X-ray and UV continuum indicators
among those that are typically available. We also find a tight relation between
soft X-ray and Mg ii2800A line fluxes, and a marginal dependence of the X-ray
to UV relation on the width of the Mg ii line. Conclusions: Our analysis
suggests that the physical quantities that are more tightly linked to one
another are the soft X-ray flux at 1 keV and the ionizing UV flux
blueward of the Lyman limit. However, the "usual" monochromatic fluxes at 2 keV
and 2500A estimated from photometric data provide an almost as-tight X-ray to
UV relation, and can be used to derive quasar distances. The Hubble diagram
obtained using spectroscopic indicators is fully consistent with the one
presented in previous papers, based on photometric data.Comment: accepted for publication in A&
Disseminate Fungal Infection after Acute Pancreatitis in a Simultaneous Pancreas-Kidney Recipient
Fungal infections after kidney transplantation are a major cause of morbidity and mortality, and Candida infection of the pancreas is considered an infrequent but important agent in necrotizing pancreatitis. We report the case of a 43-year-old Caucasian patient who underwent simultaneous pancreas-kidney transplantation because of diabetes type I, and chronic renal failure with peritoneal dialysis. The postoperative course was complicated by acute pancreatitis due to the thrombosis of the splenic artery of the graft, the subsequent acute rupture of the external iliac artery caused by fungal arteritis (Candida glabrata), and peritonitis a few days later caused by sigmoid perforation with detection of Candida glabrata infection of the resected intestinal tract. The present case remarks that awareness and prevention of fungal infection are major issues in the transplant field. Important information can be added by systematic culture of conservation perfusates but, probably, the best way for early recognition of a critical level of infectious risk remains the routine application of the colonization index screening. In cases of positive results, preemptive antifungal therapy could be warranted
Prevalence and clinical outcome of hepatic haemangioma with specific reference to the risk of rupture: a large retrospective cross-sectional study.
BACKGROUND:
Prevalence and incidence of hepatic haemangioma are estimated from autopsy series only. Although benign and generally asymptomatic, hepatic haemangioma can cause serious complications.
AIMS:
The aim of the study was to assess the prevalence of hepatic haemangioma and to attempt to quantify the risk of major complications such as spontaneous rupture.
METHODS:
We retrospectively analyzed the radiology database of a Regional University Hospital over a 7-year period: the radiological records of 83,181 patients who had an abdominal computed tomography or magnetic resonance scan were reviewed. Diagnoses made at imaging were reviewed and related to clinical course.
RESULTS:
Hepatic haemangioma was diagnosed in 2071 patients (2.5% prevalence). In 226 patients (10.9%), haemangioma had diameter of 4 cm or more (giant haemangioma). The risk of bleeding was assessed on patients without concomitant malignancies. Spontaneous bleeding occurred in 5/1067 patients (0.47%). All 5 patients had giant haemangioma: 4 had exophytic lesions and presented with haemoperitoneum; 1 with centrally located tumour experienced intrahepatic bleeding.
CONCLUSION:
Giant haemangiomas have a low but relevant risk of rupture (3.2% in this series), particularly when peripherally located and exophytic. Surgery might be considered in these cases
Breast and Axilla Treatment in Ductal Carcinoma In Situ
Ductal carcinoma in situ (DCIS) represents a challenge for the breast unit team, beginning from its difficult radiological detection and continuing with its controversial multimodal treatment and management. With the introduction of the mammographic screening, DCIS has become a common diagnosis. In fact, today DCIS is mostly identified by mammography or magnetic resonance imaging (MRI). The increased prevalence of DCIS diagnosis, in the past, raised the problem of the therapeutic management. In this chapter, the breast and axillary surgery in case of DCIS and the most controversial aspects regarding DCIS management are reviewed based on international guidelines and on the current literature
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