Solar Electric Propulsion for Future NASA Missions

Use of high-power solar arrays, at power levels ranging from approximately 500 KW to several megawatts, has been proposed for a solar-electric propulsion (SEP) demonstration mission, using a photovoltaic array to provide energy to a high-power xenon-fueled engine. One of the proposed applications of the high-power SEP technology is a mission to rendezvous with an asteroid and move it into lunar orbit for human exploration, the Asteroid Retrieval mission. The Solar Electric Propulsion project is dedicated to developing critical technologies to enable trips to further away destinations such as Mars or asteroids. NASA needs to reduce the cost of these ambitious exploration missions. High power and high efficiency SEP systems will require much less propellant to meet those requirements

Cardiac asystole at birth: Is hypovolemic shock the cause?

A birth involving shoulder dystocia can rapidly deteriorate—from a fetus with a reassuring tracing in the minutes before birth, to a neonate needing aggressive resuscitation. Infants experiencing a traumatic birth involving shoulder dystocia may be severely compromised, even when the preceding labor was uncomplicated. This paper presents two cases in which infants had normal heart beats recorded 5–10 min before birth and were born with cardiac asystole following shoulder dystocia. Often, in cases of shoulder dystocia, infants shift blood to the placenta due to the tight compressive squeeze of the body in the birth canal (along with cord compression) and thereby may be born hypovolemic. Our hypothesis is that the occurrence of sudden cardiac asystole at birth is due to extreme hypovolemic shock secondary to the loss of blood. At birth, the sudden release of pressure on the infant’s body results in hypoperfusion resulting in low central circulation and blood pressure. Severe hypovolemic shock from these effects leads to sudden cardiac arrest. Immediate cord clamping maintains the hypovolemic state by preventing the physiologic and readily available placental blood from returning to the infant. Loss of this blood initiates an inflammatory response leading to seizures, hypoxic-ischemic encephalopathy, and brain damage or death. Animal studies have shown that human umbilical stem cells injected into a rat’s abdomen after induced brain damage, can protect the rat’s brain from developing permanent injury. To prevent damage to newborns, the infant must receive the blood volume and stem cells lost at the time of descent and immediate cord clamping. Recommended countermeasures for research include: (1) resuscitation at the perineum with intact cord; or (2) milking the cord before clamping; or (3) autologous transfusion of placenta blood after the birth; or (4) rapid transfusion of O negative blood after birth and before seizures begin

Honey Bee Dopamine and Octopamine Receptors Linked to Intracellular Calcium Signaling Have a Close Phylogenetic and Pharmacological Relationship

BACKGROUND: Three dopamine receptor genes have been identified that are highly conserved among arthropod species. One of these genes, referred to in honey bees as Amdop2, shows a close phylogenetic relationship to the a-adrenergic-like octopamine receptor family. In this study we examined in parallel the functional and pharmacological properties of AmDOP2 and the honey bee octopamine receptor, AmOA1. For comparison, pharmacological properties of the honey bee dopamine receptors AmDOP1 and AmDOP3, and the tyramine receptor AmTYR1, were also examined. METHODOLOGY/PRINCIPAL FINDINGS: Using HEK293 cells heterologously expressing honey bee biogenic amine receptors, we found that activation of AmDOP2 receptors, like AmOA1 receptors, initiates a rapid increase in intracellular calcium levels. We found no evidence of calcium signaling via AmDOP1, AmDOP3 or AmTYR1 receptors. AmDOP2- and AmOA1-mediated increases in intracellular calcium were inhibited by 10 µM edelfosine indicating a requirement for phospholipase C-β activity in this signaling pathway. Edelfosine treatment had no effect on AmDOP2- or AmOA1-mediated increases in intracellular cAMP. The synthetic compounds mianserin and epinastine, like cis-(Z)-flupentixol and spiperone, were found to have significant antagonist activity on AmDOP2 receptors. All 4 compounds were effective antagonists also on AmOA1 receptors. Analysis of putative ligand binding sites offers a possible explanation for why epinastine acts as an antagonist at AmDOP2 receptors, but fails to block responses mediated via AmDOP1. CONCLUSIONS/SIGNIFICANCE: Our results indicate that AmDOP2, like AmOA1, is coupled not only to cAMP, but also to calcium-signalling and moreover, that the two signalling pathways are independent upstream of phospholipase C-β activity. The striking similarity between the pharmacological properties of these 2 receptors suggests an underlying conservation of structural properties related to receptor function. Taken together, these results strongly support phylogenetic analyses indicating that the AmDOP2 and AmOA1 receptor genes are immediate paralogs

The Journal of Comorbidity affiliates with the Society for Academic Primary Care

No abstract available

Effective lifetime radiation risk for a number of national mammography screening programmes

Background and purpose: The performance of mammography screening programmes is focussed mainly on breast cancer detection rates. However, when the benefits and risks of mammography are considered, the risk of radiation-induced cancer is calculated for only the examined breast using Mean Glandular Dose (MGD). The risk from radiation during mammography is often described as low or minimal. This study aims to evaluate the effective lifetime risk from full field digital mammography (FFDM) for a number of national screening programmes. Material and Methods: Using an ATOM phantom, radiation doses to multiple organs were measured during standard screening mammography. Sixteen FFDM machines were used and the effective lifetime risk was calculated across the female lifespan for each machine. Once the risks were calculated using the phantom, the total effective lifetime risk across 48 national screening programmes was then calculated; this assumed that all these programmes use FFDM for screening. Results: Large differences exist in effective lifetime risk, varying from 42.21 [39.12 - 45.30] cases/106 (mean [95% CI]) in the Maltese screening programme to 1099.67 [1019.25 - 1180.09] cases/106 for high breast cancer risk women in the United States of America. These differences are mainly attributed to the commencement age of screening mammography and the time interval between successive screens. Conclusions: Effective risk should be considered as an additional parameter for the assessment of screening mammography programme performance, especially for those programmes which recommend an early onset and more frequent screening mammography

A “Learning Revolution”? Investigating Pedagogic Practices around Interactive Whiteboards in British Primary Classrooms

Interactive whiteboards have been rapidly introduced into all primary schools under UK Government initiatives. These large, touch-sensitive screens, which control a computer connected to a digital projector, seem to be the first type of educational technology particularly suited for whole-class teaching and learning. Strong claims are made for their value by manufacturers and policy makers, but there has been little research on how, if at all, they influence established pedagogic practices, communicative processes and educational goals. This study has been designed to examine this issue, using observations in primary (elementary) school classrooms. It is funded by the UK Economic and Social Research Council and builds on the authors’ previous research on ICT in educational dialogues and collaborative activities