scholarly journals The Rate, Amplitude, and Duration of Outbursts from Class 0 Protostars in Orion

2022 ◽  
Vol 924 (2) ◽  
pp. L23
Author(s):  
Wafa Zakri ◽  
S. T. Megeath ◽  
William J. Fischer ◽  
Robert Gutermuth ◽  
Elise Furlan ◽  
...  

Abstract At least half of a protostar’s mass is accreted in the Class 0 phase, when the central protostar is deeply embedded in a dense, infalling envelope. We present the first systematic search for outbursts from Class 0 protostars in the Orion clouds. Using photometry from Spitzer/IRAC spanning 2004 to 2017, we detect three outbursts from Class 0 protostars with ≥2 mag changes at 3.6 or 4.5 μm. This is comparable to the magnitude change of a known protostellar FU Ori outburst. Two are newly detected bursts from the protostars HOPS 12 and 124. The number of detections implies that Class 0 protostars burst every 438 yr, with a 95% confidence interval of 161 to 1884 yr. Combining Spitzer and WISE/NEOWISE data spanning 2004–2019, we show that the bursts persist for more than nine years with significant variability during each burst. Finally, we use 19–100 μm photometry from SOFIA, Spitzer, and Herschel to measure the amplitudes of the bursts. Based on the burst interval, a duration of 15 yr, and the range of observed amplitudes, 3%–100% of the mass accretion during the Class 0 phase occurs during bursts. In total, we show that bursts from Class 0 protostars are as frequent, or even more frequent, than those from more evolved protostars. This is consistent with bursts being driven by instabilities in disks triggered by rapid mass infall. Furthermore, we find that bursts may be a significant, if not dominant, mode of mass accretion during the Class 0 phase.

2015 ◽  
Vol 12 (s1) ◽  
pp. S102-S109 ◽  
Author(s):  
Jesus Soares ◽  
Jacqueline N. Epping ◽  
Chantelle J. Owens ◽  
David R. Brown ◽  
Tina J. Lankford ◽  
...  

Background:We aimed to determine the likelihood that adult dog owners who walk their dogs will achieve a healthy level of moderate-intensity (MI) physical activity (PA), defined as at least 150 mins/wk.Methods:We conducted a systematic search of 6 databases with data from 1990–2012 on dog owners’ PA, to identify those who achieved MIPA. To compare dog-walkers’ performance with non-dog walkers, we used a random effects model to estimate the unadjusted odds ratio (OR) and corresponding 95% confidence interval (CI).Results:We retrieved 9 studies that met our inclusion criterion and allowed OR calculations. These yielded data on 6980 dog owners aged 18 to 81 years (41% men). Among them, 4463 (63.9%) walked their dogs. Based on total weekly PA, 2710 (60.7%) dog walkers, and 950 (37.7%) non-dog walkers achieved at least MIPA. The estimated OR was 2.74 (95% CI 2.09–3.60).Conclusion:Across 9 published studies, almost 2 in 3 dog owners reported walking their dogs, and the walkers are more than 2.5 times more likely to achieve at least MIPA. These findings suggest that dog walking may be a viable strategy for dog owners to help achieve levels of PA that may enhance their health.


2020 ◽  
Author(s):  
Omar Hamam ◽  
Ahmed Goda ◽  
Radwa Awad ◽  
Amr Ussama ◽  
Moustafa Eldalal ◽  
...  

ABSTRACTBackgroundThere is an increasing evidence that COVID-19 could be complicated by coagulopathy which may lead to death; especially in severe cases. Hence, this study aimed to build concrete evidence regarding the incidence and mortality of pulmonary embolism (PE) in patients with COVID-19.MethodsWe performed a systematic search for trusted databases/search engines including PubMed, Scopus, Cochrane library and Web of Science. After screening, the relevant data were extracted and the incidences and mortality rates from the different included studies were pooled for meta-analysis.ResultsTwenty studies were finally included in our study consisting of 1896 patients. The results of the meta-analysis for the all included studies showed that the incidence of PE in patients with COVID-19 was 17.6% with the 95% confidence interval (CI) of 12.7 to 22.5%. There was significant heterogeneity (I2□=□91.17%). Additionally, the results of meta-analysis including 8 studies showed that the mortality in patients with both PE and COVID-19 was 43.1% with the 95% confidence interval (CI) of 19 to 67.1%. There was significant heterogeneity (I2□=□86.96%).ConclusionPE was highly frequent in patients with COVID-19. The mortality in patients with both COVID-19 and PE was remarkable representing almost half of the patients. Appropriate prophylaxis and management are vital for better outcomes.


Author(s):  
Richard L. Leino ◽  
Jon G. Anderson ◽  
J. Howard McCormick

Groups of 12 fathead minnows were exposed for 129 days to Lake Superior water acidified (pH 5.0, 5.5, 6.0 or 6.5) with reagent grade H2SO4 by means of a multichannel toxicant system for flow-through bioassays. Untreated water (pH 7.5) had the following properties: hardness 45.3 ± 0.3 (95% confidence interval) mg/1 as CaCO3; alkalinity 42.6 ± 0.2 mg/1; Cl- 0.03 meq/1; Na+ 0.05 meq/1; K+ 0.01 meq/1; Ca2+ 0.68 meq/1; Mg2+ 0.26 meq/1; dissolved O2 5.8 ± 0.3 mg/1; free CO2 3.2 ± 0.4 mg/1; T= 24.3 ± 0.1°C. The 1st, 2nd and 3rd gills were subsequently processed for LM (methacrylate), TEM and SEM respectively.Three changes involving chloride cells were correlated with increasing acidity: 1) the appearance of apical pits (figs. 2,5 as compared to figs. 1, 3,4) in chloride cells (about 22% of the chloride cells had pits at pH 5.0); 2) increases in their numbers and 3) increases in the % of these cells in the epithelium of the secondary lamellae.


2020 ◽  
Vol 90 (1-2) ◽  
pp. 49-58 ◽  
Author(s):  
Wang Chunbin ◽  
Wang Han ◽  
Cai Lin

Abstract. Vitamin D deficiency commonly occurs in chronic heart failure. Whether additional vitamin D supplementation can be beneficial to adults with chronic heart failure remains unclear. We conducted a meta-analysis to derive a more precise estimation. PubMed, Embase, and Cochrane databases were searched on September 8, 2016. Seven randomized controlled trials that investigated the effects of vitamin D on cardiovascular outcomes in adults with chronic heart failure, and comprised 592 patients, were included in the analysis. Compared to placebo, vitamin D, at doses ranging from 2,000 IU/day to 50,000 IU/week, could not improve left ventricular ejection fraction (Weighted mean difference, WMD = 3.31, 95% confidence interval, CL = −0.93 to 7.55, P < 0.001, I2 = 92.1%); it also exerts no beneficial effects on the 6 minute walk distance (WMD = 18.84, 95% CL = −24.85 to 62.52, P = 0.276, I2 = 22.4%) and natriuretic peptide (Standardized mean difference, SMD = −0.39, 95% confidence interval CL = −0.48 to 0.69, P < 0.001, I2 = 92.4%). However, a dose-response analysis from two studies demonstrated an improved left ventricular ejection fraction with vitamin D at a dose of 4,000 IU/day (WMD = 6.58, 95% confidence interval CL = −4.04 to 9.13, P = 0.134, I2 = 55.4%). The results showed that high dose vitamin D treatment could potentially benefit adults with chronic heart failure, but more randomized controlled trials are required to confirm this result.


2006 ◽  
Author(s):  
Geoff Cumming ◽  
Melissa Coulson ◽  
Michelle Healey ◽  
Fiona Fidler

1990 ◽  
Vol 29 (03) ◽  
pp. 167-181 ◽  
Author(s):  
G. Hripcsak

AbstractA connectionist model for decision support was constructed out of several back-propagation modules. Manifestations serve as input to the model; they may be real-valued, and the confidence in their measurement may be specified. The model produces as its output the posterior probability of disease. The model was trained on 1,000 cases taken from a simulated underlying population with three conditionally independent manifestations. The first manifestation had a linear relationship between value and posterior probability of disease, the second had a stepped relationship, and the third was normally distributed. An independent test set of 30,000 cases showed that the model was better able to estimate the posterior probability of disease (the standard deviation of residuals was 0.046, with a 95% confidence interval of 0.046-0.047) than a model constructed using logistic regression (with a standard deviation of residuals of 0.062, with a 95% confidence interval of 0.062-0.063). The model fitted the normal and stepped manifestations better than the linear one. It accommodated intermediate levels of confidence well.


1995 ◽  
Vol 74 (02) ◽  
pp. 718-721 ◽  
Author(s):  
Jørgen Gram ◽  
Johannes Sidelmann ◽  
Jørgen Jespersen

SummaryMany reports have demonstrated an abnormal fibrinolysis in a subset of patients with deep vein thrombosis. We have studied systemic global fibrinolytic activity and protein concentrations of tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor type 1 (PAI-1) in plasma of 25 young patients with a previous instance of spontaneous deep vein thrombosis documented by phlebography and in 50 healthy controls. The two populations were comparable with respect to a number of base-line variables (age, height, weight, etc.), while the patients had significantly lower fibrinolytic activity (p <0.02), and significantly higher protein concentrations of t-PA (p <0.0001) and PAI-1 (p <0.0006).We used probit scale plots to identify the consequence of different cut-off points to separate patients from controls. Reasonable separation could be obtained for t-PA with a cut-off point of 5.2 ng/ml and for PAI-1 18 ng/ml. The sensitivity and specificity for these cut-off points were for t-PA 73% (95% confidence interval 63%-84%) and for PAI-1 67% (confidence interval 55%-77%). The negative predictive value with a cut-off point t-PA concentration of 5.2 ng/ml was 85% (95% confidence interval 70%-94%). We observed a significantly negative association between concentration of t-PA and fibrinolytic activity (rs = -0.47; p <0.005) and also between PAI-1 and fibrinolytic activity (rs = -0.78; p <0.005).We conclude that a young healthy population is characterized by low protein concentration of t-PA (and PAI-1) compared with young patients with a previous instance of spontaneous vein thrombosis, and we tentatively state that a low protein concentration of t-PA predicts a low risk of spontaneous deep vein thrombosis.


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