Radiation Dose Measurements in a 256-Slice Computed Tomography Scanner

Purpose: The purpose of this study is to compare computed tomography (CT) radiation dose measurement methods proposed by TG111, International Electrotechnical Commission (IEC), and a direct dose profile integral (DPI) measurement method. Methods: Pencil and Farmer ion chambers are used for integrating dose profiles at different beam widths in a 60 cm long body phantom. Resulting DPI is used to calculate CT dose index (CTDI) at each beam width. Measurements are also done for a pencil chamber inserted into a 15 cm body phantom at the reference beam width. The reference measurement is scaled with pencil chamber measurements in air at different beam widths, according to the IEC approach. Finally, point dose measurements are done with a Farmer chamber under equilibrium conditions according to the TG111 method. All CTDIs calculated from measured data are compared to the scanner displayed CTDIs. Results: Calculated CTDIs, at different beam widths, using the IEC approach are within 20% of CTDIs calculated from DPI measurements in a 60 cm long body phantom. Dose Length Integral (DLI) obtained from TG111 method is close to the results obtained from DPI measurements. Scanner displayed CTDIs are lower than all measured values by up to 38% at the techniques used. Conclusion: Although the IEC method is the easiest to use compared to the TG111 and direct DPI measurement method, it underestimates dose indices by about 20%. CTDIs displayed on the GE scanner are lower than those measured in this study by up to 38%

Performing the Union: the Prüm Decision and the European dream

In 2005, seven European countries signed the so-called Prüm Treaty to increase transnational collaboration in combating international crime, terrorism and illegal immigration. Three years later, the Treaty was adopted into EU law. EU member countries are obliged to have systems in place to allow authorities of other member states access to nationally held data on DNA, fingerprints, and vehicles by August 2011. In this paper, we discuss the conditions of possibility for the Prüm network to emerge, and argue that rather than a linear story of technological and political convergence and harmonisation, the (hi)story of Prüm is heterogeneous and patchy. This is reflected also in the early stages of implementing the Prüm Decision which proves to be more difficult than it was hoped by the drivers of the Prüm process. In this sense, the Prüm network sits uncomfortably with success stories of forensic science (many of which served the goal of justifying the expansion of technological and surveillance systems). Instead of telling a story of heroic science, the story of Prüm articulates the European dream: One in which goods, services, and people live and travel freely and securely

Unexpected retirement from full time work after age 62: consequences for life satisfaction in older Americans

Recent policy shifts in the United States have resulted in an increase in the number of older workers remaining in the labor force. Increases in the retirement age for receiving full Social Security benefits coupled with declining pension funds and the erosion of employer retiree health benefits, mean that current cohorts of older workers may fully expect to work longer than previous generations. Yet, working longer may not always be possible due to health problems, outdated skills, economic insecurity, and competing obligations. We examine the consequences of unmet expectations for full time work after age 62 for life satisfaction in a nationally representative sample of older Americans. With longitudinal data from the Health and Retirement Study (1998–2008), this paper uses repeated measures of expectations for later life work among a cohort of Americans (N=1684) gathered prospectively over an eight year period, and examines the effects of unfulfilled expectations on subsequent life satisfaction. Using generalized growth mixture modeling three latent classes of individuals were identified with distinct trajectories of later life work expectations (low expectations, high expectations, and neutral expectations for full time work after age 62). A majority of men had generally high expectations to work full time past age 62, whereas the majority of women reported a low probability of working full time after age 62. When comparing expectations to actual full time work past age 62, we found no effects of unmet expectations for women. But men with less job stability (reflected by shorter job tenure and lower incomes) generally had high expectations to work longer, and their life satisfaction scores were significantly lower when these expectations were not realized. The hazards of missed expectations for later life work have consequences for subjective well-being in older adults

Gravitating Instantons In 3 Dimensions

We study the Einstein-Chern-Simons gravity coupled to Yang-Mills-Higgs theory in three dimensional Euclidean space with cosmological constant. The classical equations reduce to Bogomol'nyi type first order equations in curved space. There are BPS type gauge theory instanton (monopole) solutions of finite action in a gravitational instanton which itself has a finite action. We also discuss gauge theory instantons in the vacuum (zero action) AdS space. In addition we point out to some exact solutions which are singular.Comment: 17 pages, 4 figures, title has changed, gravitational instanton actions are adde

Timing and Duration of Incarceration and High-Risk Sexual Partnerships Among African Americans in North Carolina

Incarceration may contribute to HIV transmission by disrupting stable partnerships and promoting high-risk partnerships. We investigated incarceration and high-risk partnerships among African Americans in North Carolina (NC)

Identification of a humanized mouse model for functional testing of immune-mediated biomaterial foreign body response.

Biomedical devices comprise a major component of modern medicine, however immune-mediated fibrosis and rejection can limit their function over time. Here, we describe a humanized mouse model that recapitulates fibrosis following biomaterial implantation. Cellular and cytokine responses to multiple biomaterials were evaluated across different implant sites. Human innate immune macrophages were verified as essential to biomaterial rejection in this model and were capable of cross-talk with mouse fibroblasts for collagen matrix deposition. Cytokine and cytokine receptor array analysis confirmed core signaling in the fibrotic cascade. Foreign body giant cell formation, often unobserved in mice, was also prominent. Last, high-resolution microscopy coupled with multiplexed antibody capture digital profiling analysis supplied spatial resolution of rejection responses. This model enables the study of human immune cell-mediated fibrosis and interactions with implanted biomaterials and devices

Blood Glucose Levels Regulate Pancreatic β-Cell Proliferation during Experimentally-Induced and Spontaneous Autoimmune Diabetes in Mice

Type 1 diabetes mellitus is caused by immune-mediated destruction of pancreatic beta-cells leading to insulin deficiency, impaired intermediary metabolism, and elevated blood glucose concentrations. While at autoimmune diabetes onset a limited number of beta-cells persist, the cells' regenerative potential and its regulation have remained largely unexplored. Using two mouse autoimmune diabetes models, this study examined the proliferation of pancreatic islet ss-cells and other endocrine and non-endocrine subsets, and the factors regulating that proliferation.We adapted multi-parameter flow cytometry techniques (including DNA-content measurements and 5'-bromo-2'-deoxyuridine [BrdU] incorporation) to study pancreatic islet single cell suspensions. These studies demonstrate that beta-cell proliferation rapidly increases at diabetes onset, and that this proliferation is closely correlated with the diabetic animals' elevated blood glucose levels. For instance, we show that when normoglycemia is restored by exogenous insulin or islet transplantation, the beta-cell proliferation rate returns towards low levels found in control animals, yet surges when hyperglycemia recurs. In contrast, other-than-ss endocrine islet cells did not exhibit the same glucose-dependent proliferative responses. Rather, disease-associated alterations of BrdU-incorporation rates of delta-cells (minor decrease), and non-endocrine islet cells (slight increase) were not affected by blood glucose levels, or were inversely related to glycemia control after diabetes onset (alpha-cells).We conclude that murine beta-cells' ability to proliferate in response to metabolic need (i.e. rising blood glucose concentrations) is remarkably well preserved during severe, chronic beta-cell autoimmunity. These data suggest that timely control of the destructive immune response after disease manifestation could allow spontaneous regeneration of sufficient beta-cell mass to restore normal glucose homeostasis