1,416 research outputs found
Multi-frequency Radio Measurements of SN 1987A over 22 Years
We present extensive observations of the radio emission from the remnant of
SN 1987A made with the Australia Telescope Compact Array (ATCA), since the
first detection of the remnant in 1990. The radio emission has evolved in time
providing unique information on the interaction of the supernova shock with the
circumstellar medium. We particularly focus on the monitoring observations at
1.4, 2.4, 4.8 and 8.6 GHz, which have been made at intervals of 4-6 weeks. The
flux density data show that the remnant brightness is now increasing
exponentially, while the radio spectrum is flattening. The current spectral
index value of -0.68 represents an 18+/-3% increase over the last 8 years. The
exponential trend in the flux is also found in the ATCA imaging observations at
9 GHz, which have been made since 1992, approximately twice a year, as well as
in the 843 MHz data set from the Molonglo Observatory Synthesis Telescope from
1987 to March 2007. Comparisons with data at different wavelengths (X-ray,
H\alpha) are made. The rich data set that has been assembled in the last 22
years forms a basis for a better understanding of the evolution of the
supernova remnant.Comment: 37 pages, 11 figures, accepted by Ap
Selecting the touched vertebra as the lowest instrumented vertebra in patients with Lenke type-1 and 2 curves: Radiographic results after a minimum 5-year follow-up
BACKGROUND: The selection of the lowest instrumented vertebra (LIV) in patients with adolescent idiopathic scoliosis (AIS) is still controversial. Although multiple radiographic methods have been proposed, there is no universally accepted guideline for appropriate selection of the LIV. We developed a simple and reproducible method for selection of the LIV in patients with Lenke type-1 (main thoracic) and 2 (double thoracic) curves and investigated its effectiveness in producing optimal positioning of the LIV at 5 years of follow-up.
METHODS: The radiographs for 299 patients with Lenke type-1 or 2 AIS curves that were included in a multicenter database were evaluated after a minimum duration of follow-up of 5 years. The touched vertebra (TV) was selected on preoperative radiographs by 2 independent examiners. The LIV on postoperative radiographs was compared with the preoperative TV. The final LIV position in relation to the center sacral vertical line (CSVL) was assessed. The CSVL-LIV distance and coronal balance in patients who had fusion to the TV were compared with those in patients who had fusion cephalad and caudad to the TV. The sagittal plane was also reviewed.
RESULTS: In 86.6% of patients, the LIV was selected at or immediately adjacent to the TV. Among patients with an A lumbar modifier, those who had fusion cephalad to the TV had a significantly greater CSVL-LIV distance than those who had fusion to the TV (p = 0.006) or caudad to the TV (p = 0.002). In the groups with B (p = 0.424) and C (p = 0.326) lumbar modifiers, there were no differences among the TV groups.
CONCLUSIONS: We recommend the TV rule as a third modifier in the Lenke AIS classification system. Selecting the TV as the LIV in patients with Lenke type-1 and 2 curves provides acceptable positioning of the LIV at long-term follow-up. The position of the LIV was not different when fusion was performed caudad to the TV but came at the expense of fewer motion segments. Patients with lumbar modifier A who had fusion cephalad to the TV had greater translation of the LIV, putting these patients at risk for poor long-term outcomes.
LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence
Contribution of isoprene to chemical budgets:A model tracer study with the NCAR CTM MOZART-4
We present a study of the sensitivity of isoprene emission calculations in a global chemistry transport model (CTM) to input land cover characteristics and analyze the impacts of changes in isoprene on the tropospheric budgets of atmospheric key species. The CTM Model for Ozone and Related Chemical Species, version 4 (MOZART-4) includes the online calculation of isoprene emissions based on the Model of Emissions of Gases and Aerosols from Nature (MEGAN), which is driven by three different land parameter inputs. We also included a tagging scheme in the CTM, which keeps track of the production of carbon containing species from isoprene oxidation. It is found that the amount of tropospheric carbon monoxide (CO), formaldehyde (HCHO) and peroxyacetylnitrate (PAN) explained by isoprene oxidation ranges from 9-16%, 15-27%, and 22-32%, depending on the isoprene emissions scenario. Changes in the global tropospheric burden with different land cover inputs can reach up to 10% for CO, 15% for HCHO, and 20% for PAN. Changes for ozone are small on a global scale, but regionally differences are as large as 3DU in the tropospheric column and as large as 5 ppbv in the surface concentrations. Our results demonstrate that a careful integration of isoprene emissions and chemistry in CTMs is very important for simulating the budgets of a number of atmospheric trace gases. We further demonstrate that the model tagging scheme has the capability of improving conventional methods of constraining isoprene emissions from space-borne HCHO column observations, especially in regions where a considerable part of the variability in the HCHO column is not related to isoprene. Copyright 2008 by the American Geophysical Union
Outcomes in pediatric studies of medium-chain acyl-coA dehydrogenase (MCAD) deficiency and phenylketonuria (PKU): a review.
BACKGROUND: Inherited metabolic diseases (IMDs) are a group of individually rare single-gene diseases. For many IMDs, there is a paucity of high-quality evidence that evaluates the effectiveness of clinical interventions. Clinical effectiveness trials of IMD interventions could be supported through the development of core outcome sets (COSs), a recommended minimum set of standardized, high-quality outcomes and associated outcome measurement instruments to be incorporated by all trials in an area of study. We began the process of establishing pediatric COSs for two IMDs, medium-chain acyl-CoA dehydrogenase (MCAD) deficiency and phenylketonuria (PKU), by reviewing published literature to describe outcomes reported by authors, identify heterogeneity in outcomes across studies, and assemble a candidate list of outcomes.
METHODS: We used a comprehensive search strategy to identify primary studies and guidelines relevant to children with MCAD deficiency and PKU, extracting study characteristics and outcome information from eligible studies including outcome measurement instruments for select outcomes. Informed by an established framework and a previously published pediatric COS, outcomes were grouped into five, mutually-exclusive, a priori core areas: growth and development, life impact, pathophysiological manifestations, resource use, and death.
RESULTS: For MCAD deficiency, we identified 83 outcomes from 52 articles. The most frequently represented core area was pathophysiological manifestations, with 33 outcomes reported in 29/52 articles (56%). Death was the most frequently reported outcome. One-third of outcomes were reported by a single study. The most diversely measured outcome was cognition and intelligence/IQ for which eight unique measurement instruments were reported among 14 articles. For PKU, we identified 97 outcomes from 343 articles. The most frequently represented core area was pathophysiological manifestations with 31 outcomes reported in 281/343 articles (82%). Phenylalanine concentration was the most frequently reported outcome. Sixteen percent of outcomes were reported by a single study. Similar to MCAD deficiency, the most diversely measured PKU outcome was cognition and intelligence/IQ with 39 different instruments reported among 82 articles.
CONCLUSIONS: Heterogeneity of reported outcomes and outcome measurement instruments across published studies for both MCAD deficiency and PKU highlights the need for COSs for these diseases, to promote the use of meaningful outcomes and facilitate comparisons across studies
Anti-cancer effects and mechanism of actions of aspirin analogues in the treatment of glioma cancer
INTRODUCTION: In the past 25 years only modest advancements in glioma treatment have been made, with patient prognosis and median survival time following diagnosis only increasing from 3 to 7 months. A substantial body of clinical and preclinical evidence has suggested a role for aspirin in the treatment of cancer with multiple mechanisms of action proposed including COX 2 inhibition, down regulation of EGFR expression, and NF-κB signaling affecting Bcl-2 expression. However, with serious side effects such as stroke and gastrointestinal bleeding, aspirin analogues with improved potency and side effect profiles are being developed. METHOD: Effects on cell viability following 24 hr incubation of four aspirin derivatives (PN508, 517, 526 and 529) were compared to cisplatin, aspirin and di-aspirin in four glioma cell lines (U87 MG, SVG P12, GOS – 3, and 1321N1), using the PrestoBlue assay, establishing IC50 and examining the time course of drug effects. RESULTS: All compounds were found to decrease cell viability in a concentration and time dependant manner. Significantly, the analogue PN517 (IC50 2mM) showed approximately a twofold increase in potency when compared to aspirin (3.7mM) and cisplatin (4.3mM) in U87 cells, with similar increased potency in SVG P12 cells. Other analogues demonstrated similar potency to aspirin and cisplatin. CONCLUSION: These results support the further development and characterization of novel NSAID derivatives for the treatment of glioma
Assessment of platelet function in patients with stroke using multiple electrode platelet aggregometry: a prospective observational study
Background
There is a link between high on-treatment platelet reactivity (HPR) and adverse vascular events in stroke. This study aimed to compare multiple electrode platelet aggregometry (MEA), in healthy subjects and ischaemic stroke patients, and between patients naive to antiplatelet drugs (AP) and those on regular low dose AP. We also aimed to determine prevalence of HPR at baseline and at 3–5 days after loading doses of aspirin.
Methods
Patients with first ever ischaemic stroke were age and sex-matched to a healthy control group. Three venous blood samples were collected: on admission before any treatment given (baseline); at 24 h and 3–5 days after standard treatment. MEA was determined using a Mutliplate® analyser and agonists tested were arachidonic acid (ASPI), adenosine diphosphate (ADP) and collagen (COL).
Results
Seventy patients (mean age 73 years [SD 13]; 42 men, 28 women) were age and sex-matched to 72 healthy subjects. Thirty-three patients were on antiplatelet drugs (AP) prior to stroke onset and 37 were AP-naive. MEA results for all agonists were significantly increased in AP-naive patients compared to healthy subjects: ADP 98 ± 31 vs 81 ± 24, p < 0.005; ASPI 117 ± 31 vs 98 ± 27, p < 0.005; COL 100 ± 25 vs 82 ± 20, p < 0.005. For patients on long term AP, 33% (10/30) of patients were considered aspirin-resistant. At 3–5 days following loading doses of aspirin, only 11.1% were aspirin resistant based on an ASPI cut-off value of 40 AU*min.
Conclusions
Many patients receiving low dose aspirin met the criteria of aspirin resistance but this was much lower at 3–5 days following loading doses of aspirin. Future studies are needed to establish the causes of HPR and potential benefits of individualizing AP treatment based on platelet function testing
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Radioecological studies related to the BANEBERRY event
On December 18, 1970, at 7:30 a.m., PST, a venting occurred at the Nevada Test Site in conjunction with the Baneberry test. The Lawrence Radiation Laboratory (LRL) Bio-Medical Research Division and the University of Utah responded to this event by activating their jointly operated air-sampling network and by gathering forage, milk, and animal samples. These data are used to calculate the dose to humans from inhalation, submersion, and food-chain contamination; food-chain contamination calculations are limited to the cow-milk pathway, but included bovine inhalation. The question of food-chain contamination is explored under both the actual situation that dairy cows were fed stored feed and under the hypothetical situation that dairy cows were fed fresh feed. Our results show that {sup 131}I was the significant radionuclide emitted by the event and that the strongest dose was received by the thyroid glands of both foraging animals and humans. The integrated concentrations of {sup 131}I were higher in the northern part of Utah; the maximum value of 1100 pCi h m{sup {minus}3} was recorded at Draper (near Salt Lake City). For conservative results, we calculated the dose to a child rather than an adult. For the actual conditions following the venting, we estimate on the basis of measurements of baled hay and or milk that the dose to an infant's thyroid via the cow-milk pathway was between 0.0065 and 0.012 rad at Draper. If cows had been continuously on fresh pasture, we estimate that the dose to the infant thyroid for the same integrated air concentration would have been 1.3 rad for dry deposition and up to 100 rad for wet deposition. 24 refs., 3 figs., 13 tabs
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Industrial contests for Oregon boys and girls : 1912
Published 1912. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalo
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Organizational Discourse: Domains, Debates, and Directions
Interest in the analysis of organizational discourse has expanded rapidly over the last two decades. In this article, we reflect critically on organizational discourse analysis as an approach to the study of organizations and management, highlighting both its strengths and areas of challenge. We begin with an explanation of the nature of organizational discourse analysis and outline some of the more significant contributions made to date. We then discuss existing classifications of approaches to the study of organizational discourse and suggest that they fall into two main categories: classifications by level of analysis and classifications by type of method. We argue that both of these approaches are inherently problematic and present an alternative way to understand the varieties of approaches to the analysis of organizational discourse based on within domain and across domain characterizations. We conclude with a discussion of the challenges that remain in the development of organizational discourse as an area of study and point to some of the opportunities for important and unique contributions to our understanding of organizations and management that this family of methods brings. © 2012 Copyright Academy of Management
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