Shallow Convection on Day 261 of GATE: Mesoscale Arcs

On 18 September 1974, a cloud cluster growing in the GATE [Global Atmospheric Research Program] ship array was examined using aircraft flying close to one another at different heights, the geostationary satellite SMS-1, and radar, rawinsonde and ship data, with a view to elucidating mechanisms of convection. In this paper we concentrate analysis on cloudy convection in the moist layer. In and above southerly surface monsoon flow approaching the cluster, clouds indigenous to the moist layer took the form of rows of tiny cumulus, and of arcs of cumulus mediocris, with patterns different from those of deeper clouds. From satellite visible images, arcs were traced for periods exceeding 2 h. Airborne photography showed that the arcs were composed of many small clouds. Radar data showed that they originated after precipitation. Apparently, throughout their life cycle, they perpetuated the pattern of an initiating dense downdraft. Eventually they yielded isolated cumulus congestus, again bearing precipitation. Aircraft recorded the distribution of thermodynamic quantities and winds at altitudes within the mixed layer, and at 537 and 1067 m. These data indicated that the arcs persisted as mesoscale circulations driven by release of latent heat in the clouds, rather than being driven by the original density current at the surface. The cloudy circulations were vigorous near and above cloud base, becoming weaker upward through altitude 1 km. The entire mesoscale circulation systems were of horizontal scale roughly 40 km. The mesoscale cloud patterns of the moist layer appeared to play a primary role in heat transfer upward within this layer, and contributed to the forcing of showering midtropospheric cloud

Pallid bands in feathers and associated stable isotope signatures reveal effects of severe weather stressors on fledgling sparrows

Citation: Ross, J. D., Kelly, J. F., Bridge, E. S., Engel, M. H., Reinking, D. L., & Boyle, W. A. (2015). Pallid bands in feathers and associated stable isotope signatures reveal effects of severe weather stressors on fledgling sparrows. Peerj, 3, 21. doi:10.7717/peerj.814In August 2013, we observed a high incidence (44%) of synchronous bands of reduced melanin (a type of fault bar we have termed "pallid bands") across the rectrices of juvenile Grasshopper Sparrows (Ammodrammus savannarum) captured near El Reno, Oklahoma. Earlier that year, on May 31, the site was struck by a severe storm which rained hailstones exceeding 5.5 cm diameter and spawned an historic 4.2 km-wide tornado <8 km to the south of the site. We hypothesized that this stressor had induced the pallid bands. An assessment of Grasshopper Sparrow nesting phenology indicated that a large number of nestlings were likely growing tail feathers when the storm hit. The pallid bands were restricted to the distal half of feathers and their widths significantly increased as a function of distance from the tip (i.e., age at formation). We predicted that if stress had caused these pallid bands, then a spike in circulating delta N-15 originating from tissue catabolism during the stress response would have been incorporated into the developing feather. From 18 juveniles captured at the site in August we measured delta N-15 and delta C-13 stable isotope ratios within four to five 0.25-0.40 mg feather sections taken from the distal end of a tail feather; the pallid band, if present, was contained within only one section. After accounting for individual and across-section variation, we found support for our prediction that feather sections containing or located immediately proximal to pallid bands (i.e., the pallid band region) would show significantly higher delta N-15 than sections outside this region. In contrast, the feathers of juveniles with pallid bands compared to normal appearing juveniles showed significantly lower delta N-15. A likely explanation is that the latter individuals hatched after the May 31 storm and had consumed a trophically-shifted diet relative to juveniles with pallid bands. Considering this, the juveniles of normal appearance were significantly less abundant within our sample relative to expectations from past cohorts (z = -2.03; p = 0.042) and, in as much, suggested widespread nest losses during the storm. Severe weather events may represent major stressors to ground-nesting birds, especially for recent fledglings. We call for others to exploit opportunities to study the effects of severe weather when these rare but devastating stressors impact established field research sites

Cardiomyopathy in offspring of diabetic rats is associated with activation of the MAPK and apoptotic pathways

<p>Abstract</p> <p>Background</p> <p>Maternal diabetes affects the developing fetal cardiovascular system. Newborn offspring of diabetic mothers can have a transient cardiomyopathy. We hypothesized that cardiomyopathic remodeling is associated with activation of the mitogen activated protein kinase (MAPK) signaling and apoptotic pathways.</p> <p>Methods</p> <p>To evaluate the effects of moderate and severe maternal hyperglycemia, pregnant rats were made diabetic with an injection of 50 mg/kg of streptozotocin. Moderately well controlled maternal diabetes was achieved with twice daily glucose checks and insulin injections. No insulin was given to severely diabetic dams. Offspring of moderate and severe diabetic mothers (OMDM and MSDM, respectively) were studied on postnatal days 1 (NB1) and 21 (NB21). Echocardiograms were performed to evaluate left ventricular (LV) dimensions and function. Myocardial MAPK and apoptotic protein levels were measured by Western blot.</p> <p>Results</p> <p>OMDM had increased cardiac mass at NB1 compared to controls that normalized at NB21. OSDM demonstrated microsomia with relative sparing of cardiac mass and a dilated cardiomyopathy at NB1. In both models, there was a persistent increase in the HW:BW and significant activation of MAPK and apoptotic pathways at NB21.</p> <p>Conclusion</p> <p>The degree of maternal hyperglycemia determines the type of cardiomyopathy seen in the offspring, while resolution of both the hypertrophic and dilated cardiomyopathies is associated with activation of MAPK signaling and apoptotic pathways.</p

Differences in Lower Extremity Kinematics Between High School Cross-Country and Young Adult Recreational Runners

# Background While previous research has assessed running kinematics for age-related differences that could increase the risk of a running-related injury, none of these studies have included high school aged runners or assessed running kinematics using 2-dimensional video analysis. # Purpose The purpose of this study was to compare sagittal plane kinematics during treadmill running in high school cross-country and young adult recreational runners using 2-dimensional motion analysis techniques. # Methods Twenty-five high school cross-country runners (13 women, 12 men) and 25 young adult recreational runners (12 women, 13 men) consented to participate in this study. Reflective markers were placed on each lower extremity over multiple anatomical landmarks. After a five-minute acclimation period in which the participants ran on a treadmill at their preferred running speed, video data were recorded at 240 frames per second for all participants while they continued to run on the treadmill. # Results There were no significant differences between left and right extremities. The young adult recreational runners exhibited significantly greater vertical excursion of the center of mass (*t* = 4.64, p = .0001) compared to the high school runners. There was no significant difference between the two age groups regarding the six other sagittal plane variables. # Conclusions The young adult recreational runners demonstrated an increased center-of-mass vertical excursion in comparison to high school cross-country runners. In addition, the results obtained in this study for kinematic variables using 2-dimensional motion analysis were similar to previously reported studies using 3-dimensional motion analysis, demonstrating that 2-dimensional motion analysis could be used for analyzing sagittal plane running kinematics in clinical settings. # Level of Evidence 4, Controlled laboratory stud

Current status of the IAG working group 4.3.7 on geodetic GNSS-R

Presentación realizada online en el Scientific Assembly of the International Association of Geodesy (2021) celebrado del 28 de junio al 2 de julio en Beijing

The tetanic depression in fast motor units of mammalian skeletal muscle can be evoked by lengthening of one initial interpulse interval

A lower than expected tetanic force (the tetanic depression) is regularly observed in fast motor units (MUs) when a higher stimulation frequency immediately follows a lower one. The aim of the present study was to determine whether prolongation of only the first interpulse interval (IPI) resulted in tetanic depression. The experiments were carried out on fast MUs of the medial gastrocnemius muscle in cats and rats. The tetanic depression was measured in each case as the force decrease of a tetanus with one IPI prolonged in relation to the tetanic force at the respective constant stimulation frequency. Force depression was observed in all cases studied and was considerably greater in cats. For cats, the mean values of force depression amounted to 28.64% for FR and 10.86% for FF MUs whereas for rats 9.30 and 7.21% for FR and FF motor units, respectively. Since the phenomenon of tetanic depression in mammalian muscle is commonly observed even after a change in only the initial interpulse interval within a stimulation pattern, it can effectively influence processes of force regulation during voluntary activity of a muscle, when motoneurones progressively increase the firing rate