Cosmological birefringence is a rotation of the polarization plane of photons coming from sources of astrophysical and cosmological origin. The rotation can also depend on the energy of the photons ...and not only on the distance of the source and on the cosmological evolution of the underlying theoretical model. In this work, we constrain few selected models for cosmological birefringence, combining CMB and astrophysical data at radio, optical, X and gamma wavelengths, taking into account the specific energy and distance dependences.
The
Planck mission will be crucial to test the robustness of the ΛCDM concordance model since the relevant cosmological parameters will be measured with much better sensitivity.
As the final ...scientific performance of
Planck depends not only on the instrumental performances, but also on the detailed knowledge of the behavior of the astrophysical foregrounds, systematic effects and their interplay, in this paper we discuss these aspects from the point of view of the CMB angular power spectrum recovery.
As an example of
Planck scientific goal we discuss the possibility to constrain the reionization history of the Universe by using E-mode polarization CMB measurements.
The Planck satellite is the third generation of space missions devoted to cosmic microwave background (CMB) measurements. It will perform two sky surveys and measure the CMB anisotropies and ...polarization between 30 and 850
GHz. The low frequency instrument is an array of 22 pseudo-correlation radiometers at 30, 44, and 70
GHz. Before integrating the complete array assembly, a first set of tests is performed for each radiometer chain assembly (RCA), consisting of two radiometers. In this paper, the test campaign experimental setup and methods are discussed.
The present study was undertaken to evaluate, by means of angiography, the anatomic pattern of arterial obstructions in the lower extremities of diabetic patients presenting with critical limb ...ischaemia. We particularly examined the differences in involvement of the foot arteries between patients with and without diabetes.
A group of 150 patients with limb-threatening ischaemia, manifested by rest pain and/or non-healing ischaemic ulcers or gangrene, underwent angiologic evaluation in prevision of vascular surgery. The patients, of whom 89 were suffering from diabetes, were examined by means of digital subtraction angiography using the Seldinger technique. In each patient, details of arterial tree were obtained from the aortoiliac to the foot arteries and the site and the extent of obstructions were determined blindly with the radiologist unaware of the patient's history of diabetes.
Diabetic patients showed significantly more obstructions in the infrapopliteal arteries when compared to the patients without diabetes who had more pronounced involvement of aortoiliac and femoropopliteal arteries. Diabetic patients, moreover, showed a higher prevalence of obstruction in posterior tibial, peroneal and plantar arteries than the non-diabetics. At the time of presentation, the age of patients did not differ between the two groups but diabetic patients had more frequent ischaemic ulcers or gangrene and less rest pain than the non-diabetics.
Our study confirms earlier reports carried out with non-angiographic methods indicating more frequent involvement of calf arteries in diabetic patients but disagrees with those which report that patients with diabetes have less occlusive disease in foot arteries.
This study was aimed at retrospectively assessing the effectiveness of transarterial chemoembolization by reviewing our six years' experience. From January, 1988, to December, 1993, chemoembolization ...was performed in more than 400 patients. Of them, 321 patients with complete follow-up were selected. The treatment was retrospectively analyzed according to survival rates. The average survival of chemoembolized patients is 12 months after the first treatment session. Average survival rates in Child A, B and C patients were, respectively, 13.79, 11.2 and 6.01 months. The patients were also divided according to tumor spread and the results follow: patients with single localizations had 15.19 months' survival, those with multiple localization 12.06 and those with tumor spread had 9.51 months' survival. The patients were divided into two groups: complete chemoembolization (group A) and incomplete chemoembolization (group B). The average survival was 15.95 months for 160 group A patients and 10.11 months for 161 group B patients. As for the number of chemoembolization sessions, 123 patients underwent only one session, 112 patients two sessions, 70 patients three, 12 patient four and 4 patients five sessions--625 sessions in all. Chemoembolization was performed every 3-4 months and was always preceded by a CT exam. Our patients were compared with an untreated group where average survival was 6.32 months. The value of CT after the first treatment in predicting survival was also studied. Finally, the methods used in all treatment are reported on, together with the general results and those in the different classes of patients.
The authors report their experience with angiographic techniques in the diagnosis of vascular complications after liver transplantation. From 1986 to 1990, 78 patients were transplanted in our ...Hospital; of them, 8 underwent angiographic investigations for vascular complications. Angiography is very important when vascular complications are suspected, in the patients with a rise in cytolytic enzymes and in bilirubine levels, with hyperpyrexia, and with bioptic confirmation of no rejection. Duplex US is useful in the evaluation of portal canalization; if there are any doubts, angiography is performed also in the preoperative phase.
Fifty patients with HCC associated with hepatic cirrhosis underwent intra-arterial injection of Lipiodol UltraFluid (LUF) during diagnostic DSA of liver parenchyma, 42 of them for a complete ...chemotherapeutic treatment, 8 for an isolated diagnostic control. LUF is known to be specifically captured by HCC neoplastic tissue, with long-term persistence in the lesion if injected in the arterial hepatic tree; this is not the case with other focal hepatic masses. Therefore LUF opacification can be used to demonstrate small daughter tumors not shown by CT or US in cases with evidence of HCC, or to diagnosis HCC in clinically positive patients with no evidence of tumor at non-invasive screening. In our series of patients, accumulation of LUF in the HCC was observed in 100% of the cases, with no false negatives. Two false positives (4%) were observed, due to CT being performed too early (it should be performed not sooner than 10 days after the injection). Overall DSA accuracy was 78%, with 22% false negatives. In 14% of the cases DSA was positive for HCC in patients with aspecific noninvasive screening. CT, performed 10 days after LUF injection, demonstrated HCC daughter tumors not depicted by US, conventional CT, and angiography, in 34% of the cases, and in 9% of the patients only CT/LUF was able to show HCC in clinically positive cases with no evidence of tumor on other imaging techniques. Specificity, sensitivity and over-all accuracy were thus 100% in our series; LUF was well tolerated by the patients, and no technical complications were observed. In our opinion, the diagnostic DSA and CT/LUF is justified only for the typification of suspected focal nodules unsuitable for biopsy: in other instances, especially in case of HCC with positive biopsy/clinical findings and focal nodular mass, the technique should be directly employed as a therapeutic approach, with the injection of lipiodolized agents to treat both primary and daughter nodules after surgery in operable patients, and to begin chemoembolization treatment in patients with intrahepatic polyfocal diffusion. DSA and LUF are therefore of primary importance in the diagnosis and therapeutic flow-chart of HCC associated with hepatic cirrhosis.
The authors report their 4-year (1984-1988) experience with TCE in the treatment of primary sacral benign/malignant and vascular bone tumors, after similar preliminary studies on aneurysmal bone ...cysts. Eleven patients were treated, for a total of 21 procedures: in 85% of the eight cases of palliative embolization, multiple instrumental approaches were needed for late revascularization, up to four consecutive embolizations in the same patients. Severe complications were observed in 19% of the procedures, due to arterial catheterization and/or instrumental maneuvers, but in none of them was surgery required. Technical results--i.e. devascularization of the mass--were optimal/suboptimal in all cases at the end of multiple procedures in the same patient: in 7/8 patients treated for palliation, however, the treatment was repeated, the late venous DSA angiographic control showing recanalization of the great vessels surrounding the lesion and/or revascularization through collateral channels. The analysis of morphological and clinical results (with reference to pain relief, dimension of the mass, and calcification at CT follow up) showed a complete pain relief in 100% of the patients treated preoperatively for palliation. The dimension of the mass was reduced in 12.5% of the cases treated for palliation, and recalcification was demonstrated on CT in 12.5% of cases. In 25.5% the mass had increased in size and in 62.5% its dimensions were unchanged. Effective pain relief was always obtained in the cases treated preoperatively. Thus, in our experience TCE of expansive lesions of the sacral bone can be considered as an effective therapeutical choice, with special reference to pain relief, for use in all inoperable cases, and as a preoperative treatment to minimize blood loss at surgery. Still, embolization materials are not completely satisfying: many of them are expensive, difficult to use and cannot be trusted to permanently occlude the vessels, which forces to intervene more than once to obtain optimal clinicomorphological results. As for malignant lesions, chemo-embolization with cytostatic substances should be used to improve the efficacy of the method. However, even through such negative judgements can be expressed on TCE, both technical and clinical results have been, in our experience, quite satisfactory, which calls for optimization of the methodology.
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