2,357 research outputs found

    Taking stock of pension reforms around the world

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    Countries around the world are reforming their pension systems. Most are reforming to reduce thefiscal costs of their existing pension systems. A few young countries are establishing new systems or are increasing the generosity of their current systems, although perhaps not always taking into account the future fiscal costs entailed in the increased generosity. The purpose of the paper is to provide a brief summary and evaluation of recent pension reforms around the world. Section 2 briefly discusses why so many countries had to reform in recent years. Section 3 describes different types of potential reform options. Section 4 provides statistics on which reform options the countries are choosing. Section 5 provides an evaluation of different reform options taking into account fiscal, intergenerational and political economy costs. The last section concludes that the only way to effectively solve the pension system issue on a permanent basis is to move toward the fully-funded defined contribution reforms currently underway in Latin America, Australia, Poland, and Kazakhstan under consideration in a variety of other countries.Information Technology,Enterprise Development&Reform,Environmental Economics&Policies,Banks&Banking Reform,Pensions&Retirement Systems

    Radiation exposure from diagnostic nuclear medicine examinations in golestan province

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    Introduction: The aim of present study was to estimate effective dose from most common procedures performed in nuclear medicine departments of Golestan province. Methods: Data of nuclear medicine procedures performed in 2 nuclear medicine departments in Golestan province were collected during 4 years. Effective dose, collective effective dose and effective dose per examination were calculated using standard dosimetry tables. Results: Based on the data of this study, results of 10437 nuclear medicine procedures performed during 4 years have lead to 3.97 mSv as average effective dose per examination and 10.37 human-Sv as mean collective effective dose. It was also revealed that Tc-99m was the main source of effective dose (98.3%), bone scan was the most common procedure (25.9%) and cardiac scan (MIBI-rest) has the highest collective effective dose (33.5%) during 4 years. Conclusion: Beside the cardiac scan which was the most common nuclear medicine procedure and the main contributor of effective dose in patients, due to geographical condition of the northeast of Iran, bone scan was the highest performed nuclear medicine examination in the Golestan province

    Comparison of three with six regions of interest analyses in patients with idiopathic constipation undertaking colon transit scintigraphy using 67Ga-citrate

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    OBJECTIVE AND INTRODUCTION: Preparation of data from 6 geometric regions of interest in the colon is time consuming, and can become impractical in the environment of busy Nuclear Medicine Departments. Therefore, we have investigated and demonstrated an alternative method for obtaining the same diagnostic information from an analysis of patients with idiopathic constipation who underwent colon transit scintigraphy using 67Ga-citrate. Data analysis methods using three regions of interest are compared to the results obtained using the more time consuming 6 regions of interest method to analyze the data. MATERIALS AND METHODS: In this study, we report our results of the comparative reanalysis of data obtained by more traditional methods. We compare 3 regions of interest (ROI) which were taken from areas including the right colon, left colon and the rectosigmoid colon, with original work using our alternative 6 (ROI) diagnostic methodology. In addition, the proximal colonic emptying (PCE) was determined at 24 hr post ingestion among members of 3 identified subject groups. RESULTS: The distribution of activity as the ingested 67Ga-citrate passes through the colon constitutes an activity profile. The mean activity position in the colon can be determined from subsequent radiographic images and from this the mean clearance time can be calculated. In quantitative assessment, this represents the time at which half of activity was eliminated from colon (mean half clearance time - MCT) which did not appear different in the reanalysis. There is no significant difference in the current study in GMC 24h, GMC 48h and GMC 72h between two groups using the Man Whitney u test (p > 0.05), while in the previous work the results were statistically significant for the two later time periods GMC (GMC 48h and GMC 72h) (p = 0.016 and p = 0.027 respectively). The PCE in the group 1 was = 2.50 (0.37); group 2, 1.57 (0.47) and group 3, 2.97. The PCE was not different between the two groups (p = 0.21). CONCLUSIONS: This investigation demonstrated that the radionuclide colon transit study using 67Ga-citrate is a safe, physiologic, and quantitative method for evaluating the transit of fecal material from cecum to rectum. Although, the visual assessment of diagnosis of the subjects in the two analyses is the same, it was not completely supported by quantitative measurements. Therefore, further studies need to be done

    Comparison of technetium-99m IgG with technetium-99m red blood cells labeling in cardiac blood-pool scintigraphy: A preliminary study

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    This first clinical prospective study was conducted to use of technetium-99m immunoglobulin G (99mTc-IgG) as compared with autologous 99mTc-red blood cells (RBC) in gated blood pool ventriculography. We studied 12 patients who referred to us for a possible diagnosis of liver hemangioma or infection. Six patients underwent gated planar blood pool (GPBP) acquisition using 99mTc-RBC and 6 GPBP acquisition using 99mTc-IgG. The use of 99mTc-IgG in cardiac blood pool studies provided comparable images to 99mTc-RBC. In conclusion, 99mTc-IgG, which is readily available and needs only a single injection, may be an attractive alternative to 99mTc-RBC for the estimation of various cardiac function parameters like left ventricular function

    The present and future status of heavy neutral leptons

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    Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, los autores pertenecientes a la UAM y el nombre del grupo de colaboración, si lo hubiereThe existence of nonzero neutrino masses points to the likely existence of multiple Standard Model neutral fermions. When such states are heavy enough that they cannot be produced in oscillations, they are referred to as heavy neutral leptons (HNLs). In this white paper, we discuss the present experimental status of HNLs including colliders, beta decay, accelerators, as well as astrophysical and cosmological impacts. We discuss the importance of continuing to search for HNLs, and its potential impact on our understanding of key fundamental questions, and additionally we outline the future prospects for next-generation future experiments or upcoming accelerator run scenario

    Corporate Acquisitions, Diversification, and the Firm’s Lifecycle

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    Lifecycle theories of mergers and diversification predict that firms make acquisitions and diversify when their internal growth opportunities become exhausted. Free cash flow theories make similar predictions. In contrast to these theories, we find that the acquisition rate of firms (defined as the number of acquisitions in an IPO cohort-year divided by the number of firms in that cohort-year) follows a u-shape through their lifecycle as public firms, with young and mature firms being equally acquisitive but more so than middle-aged firms. Firms that go public during the merger/IPO wave of the 1990s are significantly more acquisitive early in their public life than firms that go public at other times. Young public firms have a lower acquisition rate of public firms than mature firms, but the opposite is true for acquisitions of private firms and subsidiaries. Strikingly, firms diversify early in their life and there is a 41% chance that a firm’s first acquisition is a diversifying acquisition. The stock market reacts more favorably to acquisitions by young firms than to acquisitions by mature firms except for acquisitions of public firms paid for with stock. There is no evidence that the market reacts more adversely to diversifying acquisitions by young firms than to other acquisitions.

    Complete improvement in a patient with multiple irreversible defects of the left ventricle on 99m technetium-sestamibi SPECT after percutaneous coronary intervention.

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    99mTc-sestamibi has been investigated as a potential viability marker; initial studies have shown good concordance between 201Tl and 99mTc-sestamibi activities in both viable and nonviable myocardium. However, assessment of myocardial viability by 99mTc-sestamibi remains controversial for tissue recovery after revascularization. Here, we present a patient with several regions of severely diminished and irreversible (defect persisting in both early and delay images of each set scanning) defects on initial scan which were dissolved completely on the follow up scan after an intervention. In a 75 year-old Asian woman with acute myocardial infarction who received thrombolytic therapy and subjected to percutaneous coronary angiography (PCI) on day 28 after acute myocardial infarction(MI), resting 99mTc-sestamibi SPECT was applied on day 4 (initial scan) and 138 (follow up scan) after acute MI at 30 and 180 min after injection of tracer (740 MBq); Two-dimensional echocardiography was carried out at the same time. On the initial image set, there was irreversible defects in the apex, anteroapical, inferoapical, anteroseptal, septal and also anterior walls, while the follow up image was normal in all regions.The angiography intervention showed just significant stenosis on left anterior descending (LAD) vessel (95). This may highlight the failure of 99mTc-sestamibi as a marker of myocardial viability and also mandate further validating of the procedure with follow up scan or other modalities for myocardial viability investigation

    A study of the time of hospital discharge of differentiated thyroid cancer patients after receiving iodine-131 for thyroid remnant ablation treatment

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    The aim of this study was to measure the radiation exposure rate from differentiated thyroid carcinoma (DTC) patients who had received iodine-131 (131I) treatment, and to evaluate hospital discharge planning in relation to three different sets of regulations. We studied 100 patients, 78 females and 22 males, aged 13 to 79 years (mean 44.40±15.83 years) with DTC, in three Groups who were treated with 3.7, 5.5 or 7.4GBq of 131I, respectively. The external whole-body dose rates following oral administration of 131I were measured after each one of the first three hospitalization days. A multivariant linear analysis was performed, considering exposure rates as dependent variables to the administered dose for treatment, age, gender, regional and/or distant metastases, thyroglobulin (Tg), antibodies to Tg and thyroid remnant in the three dose groups. We found that the exposure rates after each of the three first days of hospitalization were 30, 50 and 70μSvh-1 at 1m. All our DTC patients had an acceptable dose rate on days 2 and 3 that allowed their hospital discharge. After only 1 day of hospitalization, just 3/11 cases showed not permissible exposure rates above 70μSvh-1. In conclusion, it is the opinion of the authors that after measuring the exposure rates, most treated, DTC patients could be discharged after only one day of hospitalization, even some of those treated with high doses of 131I (7.4GBq). Patients, who received the higher doses of 131I, should not be released before their individual exposure rate is measured
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