Nuclear currents based on the integral form of the continuity equation

We present an approach to obtain new forms of the nuclear electromagnetic current, which is based on an integral form of the continuity equation. The procedure can be used to restore current conservation in model calculations in which the continuity equation is not verified. Besides, it provides, as a particular result, the so-called Siegert's form of the nuclear current, first obtained by Friar and Fallieros by extending Siegert's theorem to arbitrary values of the momentum transfer. The new currents are explicitly conserved and permit a straightforward analysis of their behavior at both low and high momentum transfers. The results are illustrated with a simple nuclear model which includes a harmonic oscillator mean potential.Comment: 19 pages, revtex, plus 2 PS figure

Loop Evolution Observed with AIA and Hi-C

In the past decade, the evolution of EUV loops has been used to infer the loop substructure. With the recent launch of High Resolution Coronal Imager (Hi-C), this inference can be validated. In this presentation we discuss the first results of loop analysis comparing AIA and Hi-C data. In the past decade, the evolution of EUV loops has been used to infer the loop substructure. With the recent launch of High Resolution Coronal Imager (Hi-C), this inference can be validated. In this presentation we discuss the first results of loop analysis comparing AIA and Hi-C data

Sounding Rocket Instrument Development at UAHuntsville/NASA MSFC

We present an overview of solar sounding rocket instruments developed jointly by NASA Marshall Space Flight Center and the University of Alabama in Huntsville. The High Resolution Coronal Imager (Hi-C) is an EUV (19.3 nm) imaging telescope which was flown successfully in July 2012. The Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP) is a Lyman Alpha (121.6 nm) spectropolarimeter developed jointly with the National Astronomical Observatory of Japan and scheduled for launch in 2015. The Marshall Grazing Incidence X-ray Spectrograph is a soft X-ray (0.5-1.2 keV) stigmatic spectrograph designed to achieve 5 arcsecond spatial resolution along the slit

Most eastern boundary upwelling regions represent thermal refugia in the age of climate change

Eastern Boundary Upwelling Systems (EBUS) are regions where wind-driven coastal upwelling brings deep cold, nutrient-rich water to the surface and may be characterized by a coastal ‘footprint’ of sea surface temperature (SST) cooler than their surroundings. Previous studies have shown that EBUS coastal temperatures are responding differently to global ocean warming, warming slowly or not at all. However, the spatial dynamics of coastal upwelling footprints have yet to be investigated. In this paper, we use 20 years of high-resolution SST data derived from satellites (MUR SST) to test the null hypothesis that the extent of coastal upwelling footprints have remained stable over the period 2002–2022, consistent with the idea that these regions are thermal refugia. We investigate linear trends at different time scales, finding that the Humboldt and Iberian/Canary EBUS show no contraction of this footprint on annual or seasonal scales. The Benguela EBUS shows no change in its central and poleward subregions, but it exhibits contraction of the footprint in the equatorward subregion in the austral winter and spring. The California EBUS behaves differently: on the annual scale only the equatorward subregion shows contraction of the SST footprint, while on the seasonal scale, the entire EBUS show contraction during the fall or summer/fall. Summarizing the last two decades, most coastal habitats of EBUS (>80% of the areas tested) are remaining cool and may be acting as regional refugia from global warming, but this is true for some regions only during certain seasons. However, the declines in areal extent of upwelling in subregions of the California and Benguela EBUS indicate potential consequences for marine life and may help to explain changes in abundance, productivity, and redistributions of populations in these regions

Reliability of Goniometry-Based Q-Angle

Objective: To establish the stability reliability, precision, and minimum value for detecting real differences for quadriceps angle (Q-angle) measurements based on standardized protocols and surface goniometry. Design: An intratester reliability study. Setting: University research laboratory. Participants: Fifty-two healthy, young, relatively lean adults (25 men and 27 women) from the university community with no history of knee injury. Methods: Q-angle was assessed with surface goniometry on 2 separate occasions separated by 48 hours. Subjects assumed a supine position with: (1) extended hips and knees, (2) neutral hip rotational position, (3) neutral foot position, and (4) isometrically contracted quadriceps femoris muscles. The axis of a manual extendable-arm goniometer was placed over the center of the right patella with the proximal arm situated over the anterior-superior iliac spine and the distal arm over the center of the tibial tuberosity. Main Outcome Measures: Stability reliability was calculated with use of intraclass correlation (ICC, 2-way random model) and precision was calculated by standard error of measurement (SEM). The 95% limits of agreement also were calculated to estimate the minimum detectable difference in Q-angles. The lowest acceptable ICC was set at ≥0.70 for stability reliability. Results: The following ICC (SEM) values were found: all subjects = 0.88 (1.0°), men = 0.77 (1.0°), and women = 0.85 (1.0°). The 95% limits of agreement were 3° for the same 3 groups. Conclusions: The surface goniometry protocol described herein appeared to be reliable for relatively lean young men and women. Although measures were precise to 1.0°, it appears a difference of 3° may be needed to detect a real difference in Q-angles when measured in this fashion. © 2013 American Academy of Physical Medicine and Rehabilitation

Comparative Performance of Multiple Linear Regression and Biotic Ligand Models for Estimating the Bioavailability of Copper in Freshwater

An increasing number of metal bioavailability models are available for use in setting regulations and conducting risk assessments in aquatic systems. Selection of the most appropriate model is dependent on the user's needs but will always benefit from an objective, comparative assessment of the performance of available models. In 2017, an expert workshop developed procedures for assessing metal bioavailability models. The present study applies these procedures to evaluate the performance of biotic ligand models (BLMs) and multiple linear regression (MLR) models for copper. We find that the procedures recommended by the expert workshop generally provide a robust series of metrics for evaluating model performance. However, we recommend some modifications to the analysis of model residuals because the current method is insensitive to relatively large differences in residual patterns when comparing models. We also provide clarification on details of the evaluation procedure which, if not applied correctly, could mischaracterize model performance. We found that acute Cu MLR and BLM performances are quite comparable, though there are differences in performance on a species-specific basis and in the resulting water quality criteria as a function of water chemistry. In contrast, the chronic Cu MLR performed distinctly better than the BLM. Observed differences in performance are due to the smaller effects of hardness and pH on chronic Cu toxicity compared to acute Cu toxicity. These differences are captured in the chronic MLR model but not the chronic BLM, which only adjusts for differences in organism sensitivity. In general, we continue to recommend concurrent development of both modeling approaches because they provide useful comparative insights into the strengths, limitations, and predictive capabilities of each model. Environ Toxicol Chem 2021;40:1649-1661. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC

Evaluating a grading change at UCSD school of medicine: pass/fail grading is associated with decreased performance on preclinical exams but unchanged performance on USMLE step 1 scores.

BackgroundTo assess the impact of a change in preclerkship grading system from Honors/Pass/Fail (H/P/F) to Pass/Fail (P/F) on University of California, San Diego (UCSD) medical students' academic performance.MethodsAcademic performance of students in the classes of 2011 and 2012 (constant-grading classes) were collected and compared with performance of students in the class of 2013 (grading-change class) because the grading policy at UCSD SOM was changed for the class of 2013, from H/P/F during the first year (MS1) to P/F during the second year (MS2). For all students, data consisted of test scores from required preclinical courses from MS1 and MS2 years, and USMLE Step 1 scores. Linear regression analysis controlled for other factors that could be predictive of student performance (i.e., MCAT scores, undergraduate GPA, age, gender, etc.) in order to isolate the effect of the changed grading policy on academic performance. The change in grading policy in the MS2 year only, without any corresponding changes to the medical curriculum, presents a unique natural experiment with which to cleanly evaluate the effect of P/F grading on performance outcomes.ResultsAfter controlling for other factors, the grading policy change to P/F grading in the MS2 year had a negative impact on second-year grades relative to first-year grades (the constant-grading classes performed 1.65% points lower during their MS2 year compared to the MS1 year versus 3.25% points lower for the grading-change class, p < 0.0001), but had no observable impact on USMLE Step 1 scores.ConclusionsA change in grading from H/P/F grading to P/F grading was associated with decreased performance on preclinical examinations but no decrease in performance on the USMLE Step 1 examination. These results are discussed in the broader context of the multitude of factors that should be considered in assessing the merits of various grading systems, and ultimately the authors recommend the continuation of pass-fail grading at UCSD School of Medicine

Evaluating a grading change at UCSD school of medicine: pass/fail grading is associated with decreased performance on preclinical exams but unchanged performance on USMLE step 1 scores.

BackgroundTo assess the impact of a change in preclerkship grading system from Honors/Pass/Fail (H/P/F) to Pass/Fail (P/F) on University of California, San Diego (UCSD) medical students' academic performance.MethodsAcademic performance of students in the classes of 2011 and 2012 (constant-grading classes) were collected and compared with performance of students in the class of 2013 (grading-change class) because the grading policy at UCSD SOM was changed for the class of 2013, from H/P/F during the first year (MS1) to P/F during the second year (MS2). For all students, data consisted of test scores from required preclinical courses from MS1 and MS2 years, and USMLE Step 1 scores. Linear regression analysis controlled for other factors that could be predictive of student performance (i.e., MCAT scores, undergraduate GPA, age, gender, etc.) in order to isolate the effect of the changed grading policy on academic performance. The change in grading policy in the MS2 year only, without any corresponding changes to the medical curriculum, presents a unique natural experiment with which to cleanly evaluate the effect of P/F grading on performance outcomes.ResultsAfter controlling for other factors, the grading policy change to P/F grading in the MS2 year had a negative impact on second-year grades relative to first-year grades (the constant-grading classes performed 1.65% points lower during their MS2 year compared to the MS1 year versus 3.25% points lower for the grading-change class, p < 0.0001), but had no observable impact on USMLE Step 1 scores.ConclusionsA change in grading from H/P/F grading to P/F grading was associated with decreased performance on preclinical examinations but no decrease in performance on the USMLE Step 1 examination. These results are discussed in the broader context of the multitude of factors that should be considered in assessing the merits of various grading systems, and ultimately the authors recommend the continuation of pass-fail grading at UCSD School of Medicine