28 research outputs found

    The effect of stellar feedback on a Milky Way-like galaxy and its gaseous halo

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    We present the study of a set of N-body+smoothed particle hydrodynamics simulations of a Milky Way-like system produced by the radiative cooling of hot gas embedded in a dark matter halo. The galaxy and its gaseous halo evolve for 10 Gyr in isolation, which allows us to study how internal processes affect the evolution of the system. We show how the morphology, the kinematics and the evolution of the galaxy are affected by the input supernova feedback energy ESN, and we compare its properties with those of the Milky Way. Different values of ESN do not significantly affect the star formation history of the system, but the disc of cold gas gets thicker and more turbulent as feedback increases. Our main result is that, for the highest value of ESN considered, the galaxy shows a prominent layer of extraplanar cold (log (T/K) < 4.3) gas extended up to a few kiloparsec above the disc at column densities of 1019 cm-2. The kinematics of this material is in agreement with that inferred for the H I haloes of our Galaxy and NGC 891, although its mass is lower. Also, the location, the kinematics and the typical column densities of the hot (5.3 < log (T/K) < 5.7) gas are in good agreement with those determined from the O VI absorption systems in the halo of the Milky Way and external galaxies. In contrast with the observations, however, gas at log (T/K) < 5.3 is lacking in the circumgalactic region of our systems

    Detection of partial-thickness supraspinatus tendon tears: is a single direct MR arthrography series in ABER position as accurate as conventional MR arthrography?

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    The purpose of this study was to retrospectively evaluate sensitivity and specificity of a single magnetic resonance (MR) arthrography series in abduction external rotation (ABER) position compared with conventional MR arthrography for detection of supraspinatus tendon tears, with arthroscopy as gold standard, and to assess interobserver variability. Institutional review board approval was obtained; informed consent was waived. MR arthrograms of 250 patients (170 men and 80 women; mean age, 36 years) were retrospectively and independently evaluated by three observers. Oblique coronal T1-weighted fat-suppressed images, proton density, and T2-weighted images and axial T1-weighted images and oblique sagittal T1-weighted fat-suppressed images were analyzed to detect supraspinatus tendon tears. Separately, a single T1-weighted fat-suppressed oblique axial series in ABER position was evaluated. Both protocols were scored randomly without knowledge of patients' clinical history and arthroscopy results. Tears were subclassified, based on articular surface integrity and extension (Lee classification). Interobserver agreement was assessed by kappa statistics for all patients. Ninety-two of 250 patients underwent arthroscopy; sensitivity and specificity of ABER and conventional MR arthrography were calculated and compared using paired McNemar test. Weighted kappa values of ABER and conventional MR arthrography were 0.48-0.65 and 0.60-0.67, respectively. According to arthroscopy, 69 of 92 patients had an intact cuff, and 23 patients had a cuff tear (16 partial thickness and seven full thickness). There were no statistically significant differences between ABER and conventional MR arthrography regarding sensitivity (48-61% and 52-70%, respectively) and specificity (80-94% and 91-95%). Sensitivity and specificity of a single T1-weighted series in ABER position and conventional MR arthrography are comparable for assessment of rotator cuff tear

    Feasibility study of computed tomography colonography using limited bowel preparation at normal and low-dose levels study

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    The purpose was to evaluate low-dose CT colonography without cathartic cleansing in terms of image quality, polyp visualization and patient acceptance. Sixty-one patients scheduled for colonoscopy started a low-fiber diet, lactulose and amidotrizoic-acid for fecal tagging 2 days prior to the CT scan (standard dose, 5.8–8.2 mSv). The original raw data of 51 patients were modified and reconstructed at simulated 2.3 and 0.7 mSv levels. Two observers evaluated the standard dose scan regarding image quality and polyps. A third evaluated the presence of polyps at all three mSv levels in a blinded prospective way. All observers were blinded to the reference standard: colonoscopy. At three times patients were given questionnaires relating to their experiences and preference. Image quality was sufficient in all patients, but significantly lower in the cecum, sigmoid and rectum. The two observers correctly identified respectively 10/15 (67%) and 9/15 (60%) polyps ≥10 mm, with 5 and 8 false-positive lesions (standard dose scan). Dose reduction down to 0.7 mSv was not associated with significant changes in diagnostic value (polyps ≥10 mm). Eighty percent of patients preferred CT colonography and 13% preferred colonoscopy (P<0.001). CT colonography without cleansing is preferred to colonoscopy and shows sufficient image quality and moderate sensitivity, without impaired diagnostic value at dose-levels as low as 0.7 mSv

    A critical review and development of a conceptual model of exclusion from social relations for older people

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    Social exclusion is complex and dynamic, and it leads to the non-realization of social, economic, political or cultural rights or participation within a society. This critical review takes stock of the literature on exclusion of social relations. Social relations are defined as comprising social resources, social connections and social networks. An evidence review group undertook a critical review which integrates, interprets and synthesizes information across studies to develop a conceptual model of exclusion from social relations. The resulting model is a subjective interpretation of the literature and is intended to be the starting point for further evaluations. The conceptual model identifies individual risks for exclusion from social relations (personal attributes, biological and neurological risk, retirement, socio-economic status, exclusion from material resources and migration). It incorporates the evaluation of social relations, and the influence of psychosocial resources and socioemotional processes, sociocultural, social-structural, environmental and policy contextual influences on exclusion from social relations. It includes distal outcomes of exclusion from social relations, that is, individual well-being, health and functioning, social opportunities and social cohesion. The dynamic relationships between elements of the model are also reported. We conclude that the model provides a subjective interpretation of the data and an excellent starting point for further phases of conceptual development and systematic evaluation(s). Future research needs to consider the use of sophisticated analytical tools and an interdisciplinary approach in order to understand the underlying biological and ecopsychosocial associations that contribute to individual and dynamic differences in the experience of exclusion from social relation

    Many Labs 2: Investigating Variation in Replicability Across Samples and Settings

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    We conducted preregistered replications of 28 classic and contemporary published findings, with protocols that were peer reviewed in advance, to examine variation in effect magnitudes across samples and settings. Each protocol was administered to approximately half of 125 samples that comprised 15,305 participants from 36 countries and territories. Using the conventional criterion of statistical significance (p < .05), we found that 15 (54%) of the replications provided evidence of a statistically significant effect in the same direction as the original finding. With a strict significance criterion (p < .0001), 14 (50%) of the replications still provided such evidence, a reflection of the extremely highpowered design. Seven (25%) of the replications yielded effect sizes larger than the original ones, and 21 (75%) yielded effect sizes smaller than the original ones. The median comparable Cohen’s ds were 0.60 for the original findings and 0.15 for the replications. The effect sizes were small (< 0.20) in 16 of the replications (57%), and 9 effects (32%) were in the direction opposite the direction of the original effect. Across settings, the Q statistic indicated significant heterogeneity in 11 (39%) of the replication effects, and most of those were among the findings with the largest overall effect sizes; only 1 effect that was near zero in the aggregate showed significant heterogeneity according to this measure. Only 1 effect had a tau value greater than .20, an indication of moderate heterogeneity. Eight others had tau values near or slightly above .10, an indication of slight heterogeneity. Moderation tests indicated that very little heterogeneity was attributable to the order in which the tasks were performed or whether the tasks were administered in lab versus online. Exploratory comparisons revealed little heterogeneity between Western, educated, industrialized, rich, and democratic (WEIRD) cultures and less WEIRD cultures (i.e., cultures with relatively high and low WEIRDness scores, respectively). Cumulatively, variability in the observed effect sizes was attributable more to the effect being studied than to the sample or setting in which it was studied.UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Sociales::Instituto de Investigaciones Psicológicas (IIP

    Perinatal mortality: clinical value of postmortem magnetic resonance imaging compared with autopsy in routine obstetric practice

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    Objective To compare postmortem magnetic resonance imaging (MRI) with autopsy in perinatal deaths. To determine the acceptance and feasibility of postmortem perinatal MRI. Design Cohort study. Setting Large teaching hospital. Population Fetuses and neonates from 16 weeks gestational age until 28 days after birth, stillbirths as well as intrapartum and neonatal deaths. Methods MRI was performed prior to autopsy in a consecutive cohort of perinatal deaths after full parental consent. Agreement between MRI and autopsy was calculated. The consent rate for both examinations was recorded separately, as well as the time between the perinatal death and the MRI. Main outcome measure Full agreement between MRI and autopsy. Results Of 58 cases, 26 parents consented to both examinations (45%). Autopsy showed 18 major malformations, of which 10 were detected with MRI. The positive predictive value of MRI was 80% (4/5) and the negative predictive value was 65% (13/20). Additional consent for MRI was given in eight cases (14%). In 84%, the MRI could be performed within 48 hours. Conclusions MRI is of value if autopsy is refused, but diagnostic accuracy is insufficient to recommend substitution of full autopsy. The acceptance rate of MRI only is better than that of autops

    Ten percent re-dislocation rate 13 years after the arthroscopic Bankart procedure

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    Purpose: The aim of the present study was to determine the long-term outcome after the arthroscopic Bankart procedure, in terms of recurrent instability, shoulder function, glenohumeral arthropathy and patient satisfaction. Methods: Patients who underwent the arthroscopic Bankart procedure between January 1999 and the end of December 2005 were invited to complete a set of Patient Reported Outcome Measures (PROMs) and visit the hospital for clinical and radiological assessment. PROMs included the Western Ontario Shoulder Instability Index (WOSI), the Oxford Shoulder Instability Score (OSIS) and additional questions on shoulder instability and patient satisfaction. Clinical assessment included the apprehension test and the Constant–Murley score. The Samilson–Prieto classification was used to assess arthropathy on standard radiographs. The primary outcome was a re-dislocation that needed reduction. Secondary outcomes in terms of recurrent instability included patient-reported subluxation and a positive apprehension test. Results: Of 104 consecutive patients, 71 patients with a mean follow-up of 13.1 years completed the PROMs, of which 53 patients (55 shoulders) were also available for clinical and radiological assessment. Re-dislocations had occurred in 7 shoulders (9.6%). Subluxations occurred in 23 patients (31.5%) and the apprehension test was positive in 30 (54.5%) of the 55 shoulders examined. Median functional outcomes were 236 for WOSI, 45 for OSIS, and 103 for the normalized Constant–Murley score. Of all 71 patients (73 shoulders), 29 (39.7%) reported being completely satisfied, 33 (45.2%) reported being mostly satisfied and 8 (11%) reported being somewhat satisfied. Glenohumeral arthropathy was observed in 33 (60%) of the shoulders. Conclusion: Despite 10% re-dislocations and frequent other signs of recurrent instability, shoulder function and patient satisfaction at 13 years after arthroscopic Bankart repair were good. Level of evidence: Level IV

    MR Colonography with limited bowel preparation: Patient acceptance compared with that of full-preparation Colonoscopy

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    Purpose: To prospectively evaluate participants' experience and preference of magnetic resonance (MR) colonography with limited bowel preparation compared with full-preparation colonoscopy in participants at increased risk for colorectal cancer. Materials and Methods: This study had institutional review board approval; all participants gave written informed consent. In this multicenter study, consecutive participants undergoing conventional colonoscopy because of a personal or family history of colorectal cancer or adenomatous polyps underwent MR colonography 2 weeks prior to colonoscopy. They all followed a low-fiber diet and were given lactulose and an oral contrast agent (fecal tagging with gadolinium) 2 days before colonography. Before imaging, spasmolytics were administered intravenously, and a water-gadolinium chelate mixture was administered rectally for distention of the colon. Breath-hold T1- and T2-weighted sequences were performed in the prone and supine positions. Participant experience in terms of, for example, pain and burden was determined by using a five-point scale and was evaluated with a Wilcoxon signed rank test; participant preference was determined by using a seven-point scale and was evaluated with the X 2 statistic after dichotomizing. Results: Two hundred nine participants (77 women, 132 men; mean age, 58 years: range, 23-84 years) were included. One hundred forty-eight participants received sedatives (midazolam) and/or analgesics (fentanyl) during colonoscopy. Participants rated the MR colonography bowel preparation as less burdensome (P <.001) compared with the colonoscopy bowel preparation (10% and 71% of participants rated the respective examinations moderately to extremely burdensome). Participants also experienced less pain at MR colonography (P <.001) and found MR colonography less burdensome (P <.001). Immediately after both examinations, 69% of participants preferred MR colonography, 22% preferred colonoscopy, and 9% were indifferent (P <.001, 69% vs 22%). After 5 weeks, 65% preferred MR colonography and 26% preferred colonoscopy (P <.001). Conclusion: Participants preferred MR colonography without extensive cleansing to colonoscopy immediately after both examinations and 5 weeks later. Experience of the bowel preparation and of the procedure was rated bette
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