It is a standard procedure in many countries that response to a nuclear or radiological accident or incident would involve mobile aerial- or ground-based survey with highly sensitive gamma-ray ...detectors to map the distribution of radioactivity. There may however arise situations in which ground- or air-based detectors are not able to access an area to survey for radioactive materials, therefore technologies and techniques that can estimate the position and activity of radioactive materials from a distance are under development. Tomographic reconstruction methods, well-known in medical physics, permit the reconstruction of an N-dimensional map or image, from a number of N-1-dimensional cross-sectional images, or back-projections. We are investigating a tomographic reconstruction method to reconstruct the radioactivity distribution within a restricted-access zone using measurements from a Compton gamma imager placed at several locations around the perimeter of the zone. In this work an extended source of La-140 with an activity of 35 GBq was deposited within a 500 m by 500 m zone that was surveyed from the perimeter at six locations using a Silicon photomultiplier-based Compton Telescope for Safety and Security (SCoTSS) gamma imager. The reconstructed Compton images from multiple viewpoints were then projected back into the zone to reconstruct the distribution of La-140 within it. This tomographic method reconstructed high intensity along the known location of the La-140 source, suggesting that the method is able to localize the radioactive material. A simple fit to measured counts using a point-source approximation of the source distribution yielded a strength estimate of (7 ± 2) GBq at time of deposition, a reasonable result given the presence of soil and snow attenuation. Our method provides an expedient estimate of the distribution of radioactivity using tomographic techniques. It may be used to inform decisions made on the scene in urgent situations where the distribution of radioactivity must be reconstructed from a distance.
•Deployed a scintillator and silicon-photomultiplier-based Compton imager, SCoTSS.•Developed a tomographic reconstruction method for Compton gamma-ray imaging.•Applied tomographic technique to large-area La-140 source at large distances.
A Default Mode of Brain Function Raichle, Marcus E.; MacLeod, Ann Mary; Snyder, Abraham Z. ...
Proceedings of the National Academy of Sciences - PNAS,
01/2001, Volume:
98, Issue:
2
Journal Article
Peer reviewed
Open access
A baseline or control state is fundamental to the understanding of most complex systems. Defining a baseline state in the human brain, arguably our most complex system, poses a particular challenge. ...Many suspect that left unconstrained, its activity will vary unpredictably. Despite this prediction we identify a baseline state of the normal adult human brain in terms of the brain oxygen extraction fraction or OEF. The OEF is defined as the ratio of oxygen used by the brain to oxygen delivered by flowing blood and is remarkably uniform in the awake but resting state (e.g., lying quietly with eyes closed). Local deviations in the OEF represent the physiological basis of signals of changes in neuronal activity obtained with functional MRI during a wide variety of human behaviors. We used quantitative metabolic and circulatory measurements from positron-emission tomography to obtain the OEF regionally throughout the brain. Areas of activation were conspicuous by their absence. All significant deviations from the mean hemisphere OEF were increases, signifying deactivations, and resided almost exclusively in the visual system. Defining the baseline state of an area in this manner attaches meaning to a group of areas that consistently exhibit decreases from this baseline, during a wide variety of goal-directed behaviors monitored with positron-emission tomography and functional MRI. These decreases suggest the existence of an organized, baseline default mode of brain function that is suspended during specific goal-directed behaviors.
ABSTRACT
This paper reports observations of a 22 GHz water maser ‘superburst’ in the G25.65+1.05 massive star-forming region, conducted in response to an alert from the Maser Monitoring Organisation ...(M2O). Very long baseline interferometry (VLBI) observations using the European VLBI Network (EVN) recorded a maser flux density of 1.2 × 104 Jy. The superburst was investipgated in the spectral, structural, and temporal domains and its cause was determined to be an increase in maser path length generated by the superposition of multiple maser emitting regions aligning in the line of sight to the observer. This conclusion was based on the location of the bursting maser in the context of the star-forming region, its complex structure, and its rapid onset and decay.
Background. Incidence rates of renal replacement therapy (RRT) for end-stage renal disease vary considerably worldwide. This study examines the independent association between the general population, ...health care system and renal service characteristics and RRT incidence rates.
Methods. RRT incidence data (2003-2005) were obtained from renal registries; general population age and health and macroeconomic indices were collected from secondary sources. Renal service organization and resource data were obtained through interviews and questionnaires. Linear regression models were built to establish the factors independently associated with RRT incidence, stratified by the Human Development Index where required. False discovery rate (FDR) correction was adjusted for multiple testing.
Results. Across the 46 countries (population 1.25 billion), RRT incidence rates ranged from 12 to 455 (median 130) per million population. Gross domestic product (GDP) per capita incidence rate ratio (IRR): 1.02 per $1000 increase, PFDR = 0.047, percentage of GDP spent on health care (IRR: 1.11 per % increase, PFDR = 0.006) and dialysis facility reimbursement rate relative to GDP (IRR: 0.76 per GDP per capita-sized increase in reimbursement rate, PFDR = 0.007) were independently associated with RRT incidence. In more developed countries, the private for-profit share of haemodialysis facilities was also associated with higher incidence (IRR: 1.009 per % increase, PFDR = 0.003).
Conclusions. Macroeconomic and renal service factors are more often associated with RRT incidence rates than measured demographic or general population health status factors.
As of December 31, 1998, 35 deaths had been attributed to new variant Creutzfeldt‐Jakob disease (nvCJD) in the United Kingdom, of which 33 cases had been neuropathologically confirmed and 2 ...classified as probable nvCJD. Fifteen cases were male and 20 female. The median illness duration was 14 months (range, 8–38 months) and the median age at death was 29 years (range, 18–53 years). The clinical features were consistent with previous descriptions. In nearly all cases, there were early psychiatric symptoms after a median period of 6 months ataxia developed, followed by involuntary movements and cognitive impairment. Electroencephalograms did not show the “typical” appearances found in sporadic CJD, about half the cases tested had a positive 14‐3‐3 immunoassay, and over 70% of cases had bilateral pulvinar high signal on magnetic resonance brain scanning. Prion protein gene analysis showed that all cases were homozygous for methionine at codon 129. Diagnostic criteria for nvCJD have been formulated, which have a high sensitivity and specificity. Ann Neurol 2000;47:575–582
Background
Postmarketing reports suggest that finasteride causes sexual dysfunction despite a low incidence reported in clinical trials. Therefore, the extent of risk remains unknown.
Objective
To ...determine whether the risk of sexual dysfunction is higher among individuals treated with finasteride compared to a baseline risk for all other drugs using the U.S. Food and Drug Administration Adverse Event Reporting System (FAERS) database.
Methods
A case by non‐case disproportionality approach was used whereby a reporting odds ratio (ROR) with 95% confidence interval (CI) was calculated. The National Ambulatory Medical Care Survey (NAMCS) was used to confirm results.
Results
A significant disproportionality in reporting of sexual dysfunction with the use of finasteride was observed whether finasteride was indicated for hair loss (ROR = 138.17, 95% CI: 133.13, 143.4), prostatic hyperplasia (ROR = 93.88, 95% CI: 84.62, 104.16) or any indication (ROR = 173.18, 95% CI: 171.08, 175.31). When these results were stratified by age, disproportionality was strongest at 31–45 years.
Conclusion
Use of finasteride has led to an increase in reports of sexual dysfunction where it is believed to be the primary suspect.
This international multidisciplinary document intends to provide clinicians with evidence-based practical patient-centered recommendations for evaluating patients and decedents with (aborted) sudden ...cardiac arrest and their families. The document includes a framework for the investigation of the family allowing steps to be taken, should an inherited condition be found, to minimize further events in affected relatives. Integral to the process is counseling of the patients and families, not only because of the emotionally charged subject, but because finding (or not finding) the cause of the arrest may influence management of family members. The formation of multidisciplinary teams is essential to provide a complete service to the patients and their families, and the varied expertise of the writing committee was formulated to reflect this need. The document sections were divided up and drafted by the writing committee members according to their expertise. The recommendations represent the consensus opinion of the entire writing committee, graded by Class of Recommendation and Level of Evidence. The recommendations were opened for public comment and reviewed by the relevant scientific and clinical document committees of the Asia Pacific Heart Rhythm Society (APHRS) and the Heart Rhythm Society (HRS); the document underwent external review and endorsement by the partner and collaborating societies. While the recommendations are for optimal care, it is recognized that not all resources will be available to all clinicians. Nevertheless, this document articulates the evaluation that the clinician should aspire to provide for patients with sudden cardiac arrest, decedents with sudden unexplained death, and their families.
Ammonia masers towards G 358.931−0.030 McCarthy, T P; Breen, S L; Kaczmarek, J F ...
Monthly notices of the Royal Astronomical Society,
05/2023, Volume:
522, Issue:
3
Journal Article
Peer reviewed
Open access
ABSTRACT
We report the detection of ammonia masers in the non-metastable (6, 3), (7, 5), and (6, 5) transitions; the latter being the first unambiguous maser detection of that transition ever made. ...Our observations include the first very long baseline interferometry detection of ammonia maser emission, which allowed effective constraining of the (6, 5) maser brightness temperature. The masers were detected towards G 358.931−0.030, a site of 6.7-GHz class II methanol maser emission that was recently reported to be undergoing a period of flaring activity. These ammonia masers appear to be flaring contemporaneously with the class II methanol masers during the accretion burst event of G 358.931−0.030. This newly detected site of ammonia maser emission is only the 12th such site discovered in the Milky Way. We also report the results of an investigation into the maser pumping conditions, for all three detected masing transitions, through radiative transfer calculations constrained by our observational data. These calculations support the hypothesis that the ammonia (6, 5) maser transition is excited through high colour temperature infrared emission, with the (6, 5) and (7, 5) transition line ratio implying dust temperatures >400 K. Additionally, we detect significant linearly polarized emission from the ammonia (6, 3) maser line. Alongside our observational and radiative transfer calculation results, we also report newly derived rest frequencies for the ammonia (6, 3) and (6, 5) transitions.
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