Pituitary-adrenal axis in Prader Willi syndrome

Purpose: Prader Willi syndrome (PWS) is a rare genetic condition that has concurrent endocrinological insufficiencies. The presence of growth hormone deficiency has been well documented, but adrenal insufficiency (AI) is not widely reported. A review was conducted to investigate its prevalence and relevance in PWS in both adults and children. Methodology: A literature review was performed with the search terms “Prader-Willi syndrome” and “adrenal insufficiency”. Results: The review found studies disagree on the prevalence and method of investigation of AI in PWS. Case studies demonstrate that patients with PWS are at risk of premature death, often secondary to respiratory infections. The possibility that this may be the result of the inability to mount an effective cortisol response has been studied, with some evidence confirming AI in PWS patients. Most reports agreed AI is present in PWS, however, Farholt et al. showed no HPA axis dysfunction in adults, suggesting that perhaps it is rare in adults, and children should be the focus of further studies. Conclusion: AI is present in some patients with PWS. Further research is required to ensure optimal treatment can be implemented and to prevent premature deaths related to adrenal insufficiency. Clinicians should have a low threshold for testing the adrenal axis and considering treatment for adrenal insufficiency in PWS patients

Computational design of natural laminar flow wings for transonic transport application

Two research programs are described which directly relate to the application of natural laminar flow (NLF) technology to transonic transport-type wind planforms. Each involved using state-of-the-art computational methods to design three-dimensional wing contours which generate significant runs of favorable pressure gradients. The first program supported the Variable Sweep Transition Flight Experiment and involves design of a full-span glove which extends from the leading edge to the spoiler hinge line on the upper surface of an F-14 outer wing panel. Boundary-layer and static-pressure data will be measured on this design during the supporting wind-tunnel and flight tests. These data will then be analyzed and used to infer the relationship between crossflow and Tollmein-Schlichting disturbances on laminar boundary-layer transition. A wing was designed computationally for a corporate transport aircraft in the second program. The resulting wing design generated favorable pressure gradients from the leading edge aft to the mid-chord on both upper and lower surfaces at the cruise design point. Detailed descriptions of the computational design approach are presented along with the various constraints imposed on each of the designs. Wing surface pressure distributions, which support the design objective and were derived from transonic three-dimensional analyses codes, are also presented. Current status of each of the research programs is included in the summary

Symbiont 'bleaching' in planktic foraminifera during the Middle Eocene Climatic Optimum

Many genera of modern planktic foraminifera are adapted to nutrient-poor (oligotrophic) surface waters by hosting photosynthetic symbionts, but it is unknown how they will respond to future changes in ocean temperature and acidity. Here we show that ca. 40 Ma, some fossil photosymbiont-bearing planktic foraminifera were temporarily 'bleached' of their symbionts coincident with transient global warming during the Middle Eocene Climatic Optimum (MECO). At Ocean Drilling Program (ODP) Sites 748 and 1051 (Southern Ocean and mid-latitude North Atlantic, respectively), the typically positive relationship between the size of photosymbiont-bearing planktic foraminifer tests and their carbon isotope ratios (δ13C) was temporarily reduced for ∼100 k.y. during the peak of the MECO. At the same time, the typically photosymbiont-bearing planktic foraminifera Acarinina suffered transient reductions in test size and relative abundance, indicating ecological stress. The coincidence of minimum δ18O values and reduction in test size–δ13C gradients suggests a link between increased sea-surface temperatures and bleaching during the MECO, although changes in pH and nutrient availability may also have played a role. Our findings show that host-photosymbiont interactions are not constant through geological time, with implications for both the evolution of trophic strategies in marine plankton and the reliability of geochemical proxy records generated from symbiont-bearing planktic foraminifera

New biostratigraphic, magnetostratigraphic and isotopic insights into the Middle Eocene Climatic Optimum in low latitudes

The Middle Eocene Climatic Optimum (MECO) was a warming event that interrupted the long-term Eocene cooling trend. While this event is well documented at high southern and mid-latitudes, it is poorly known from low latitudes and its timing and duration are not well constrained because of problems of hiati, microfossil preservation and weak magnetic polarity in key sedimentary sections. Here, we report the results of a study designed to improve the bio-, magneto- and chemostratigraphy of the MECO interval using high-resolution records from two low-latitude sections in the Atlantic Ocean, Ocean Drilling Program (ODP) Sites 1051 and 1260. We present the first detailed benthic foraminiferal stable isotope records of the MECO from the low latitudes as well as the biostratigraphic counts of Orbulinoides beckmanni and new magnetostratigraphic results. Our data demonstrate a ~ 750 kyr-long duration for the MECO characterized by increasing δ13C and decreasing δ18O, with minimum δ18O values lasting ~ 40 kyr at 40.1 Ma coincident with a short-lived negative δ13C excursion. Thereafter, δ18O and δ13C values recover rapidly. The shift to minimum δ18O values at 40.1 Ma is coincident with a marked increase in the abundance of the planktonic foraminifera O. beckmanni, consistent with its inferred warm-water preference. O. beckmanni is an important Eocene biostratigraphic marker, defining planktonic foraminiferal Zone E12 with its lowest and highest occurrences (LO and HOs). Our new records reveal that the LO of O. beckmanni is distinctly diachronous, appearing ~ 500 kyr earlier in the equatorial Atlantic than in the subtropics (40.5 versus 41.0 Ma). We also show that, at both sites, the HO of O. beckmanni at 39.5 Ma is younger than the published calibrations, increasing the duration of Zone E12 by at least 400 kyr. In accordance with the tropical origins of O. beckmanni, this range expansion to higher latitudes may have occurred in response to sea surface warming during the MECO and subsequently disappeared with cooling of surface waters

Socially-mediated arousal and contagion within domestic chick broods

Emotional contagion – an underpinning valenced feature of empathy – is made up of simpler, potentially dissociable social processes which can include socially-mediated arousal and behavioural/physiological contagion. Previous studies of emotional contagion have often conflated these processes rather than examining their independent contribution to empathic response. We measured socially-mediated arousal and contagion in 9-week old domestic chicks (n = 19 broods), who were unrelated but raised together from hatching. Pairs of observer chicks were exposed to two conditions in a counterbalanced order: air puff to conspecifics (AP) (during which an air puff was applied to three conspecifics at 30 s intervals) and control with noise of air puff (C) (during which the air puff was directed away from the apparatus at 30 s intervals). Behaviour and surface eye temperature of subjects and observers were measured throughout a 10-min pre-treatment and 10-min treatment period. Subjects and observers responded to AP with increased freezing, and reduced preening and ground pecking. Subjects and observers also showed reduced surface eye temperature - indicative of stress-induced hyperthermia. Subject-Observer behaviour was highly correlated within broods during both C and AP conditions, but with higher overall synchrony during AP. We demonstrate the co-occurrence of socially-mediated behavioural and physiological arousal and contagion; component features of emotional contagion

Rayleigh and depinning instabilities of forced liquid ridges on heterogeneous substrates

Depinning of two-dimensional liquid ridges and three-dimensional drops on an inclined substrate is studied within the lubrication approximation. The structures are pinned to wetting heterogeneities arising from variations of the strength of the short-range polar contribution to the disjoining pressure. The case of a periodic array of hydrophobic stripes transverse to the slope is studied in detail using a combination of direct numerical simulation and branch-following techniques. Under appropriate conditions the ridges may either depin and slide downslope as the slope is increased, or first breakup into drops via a transverse instability, prior to depinning. The different transition scenarios are examined together with the stability properties of the different possible states of the system.Comment: Physics synopsis link: http://physics.aps.org/synopsis-for/10.1103/PhysRevE.83.01630