Cell-cell contact area affects Notch signaling and Notch-dependent patterning

During development, cells undergo dramatic changes in their morphology. By affecting contact geometry, these morphological changes could influence cellular communication. However, it has remained unclear whether and how signaling depends on contact geometry. This question is particularly relevant for Notch signaling, which coordinates neighboring cell fates through direct cell-cell signaling. Using micropatterning with a receptor trans-endocytosis assay, we show that signaling between pairs of cells correlates with their contact area. This relationship extends across contact diameters ranging from microns to tens of microns. Mathematical modeling predicts that dependence of signaling on contact area can bias cellular differentiation in Notch-mediated lateral inhibition processes, such that smaller cells are more likely to differentiate into signal-producing cells. Consistent with this prediction, analysis of developing chick inner ear revealed that ligand-producing hair cell precursors have smaller apical footprints than non-hair cells. Together, these results highlight the influence of cell morphology on fate determination processes

Management of primary chronic headache in the general population: the Akershus study of chronic headache

Primary chronic headaches cause more disability and necessitate high utilisation of health care. Our knowledge is based on selected populations, while information from the general population is largely lacking. An age and gender-stratified cross-sectional epidemiological survey included 30,000 persons aged 30–44 years. Respondents with self-reported chronic headache were interviewed by physicians. The International Classification of Headache Disorders was used. Of all primary chronic headache sufferers, 80% had consulted their general practitioner (GP), of these 19% had also consulted a neurologist and 4% had been hospitalised. Co-occurrence of migraine increased the probability of contact with a physician. A high Severity of Dependence Scale score increased the probability for contact with a physician. Complementary and alternative medicine (CAM) was used by 62%, most often physiotherapy, acupuncture and chiropractic. Contact with a physician increased the probability of use of CAM. Acute headache medications were taken by 87%, while only 3% used prophylactic medication. GPs manage the majority of those with primary chronic headache, 1/5 never consults a physician for their headache, while approximately 1/5 is referred to a neurologist or hospitalised. Acute headache medication was frequently overused, while prophylactic medication was rarely used. Thus, avoidance of acute headache medication overuse and increased use of prophylactic medication may improve the management of primary chronic headaches in the future

Refrigeration& air conditioning technology

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Status of TRMM Ground Validation Program at NASA GSFC

The TRMM Ground Validation (GV) program at NASA GSFC has made considerable progress: over the last several years. The GV program now has a Complete record of Level I-HI products from the Kwajaiein and Melbourne, Florida sites. Current emphasis is to eliminate the remaining backlog for the Houston, Texas and Darwin, Australia sites. This paper provides details on the status of our data processing efforts, defines accuracy estimates of the various GV rain products, end shows comparisons between GV rain intensities and accumulations to satellite retrievals over the GV sites. We will show that the Version 6a TRMM TMI and PR, at leas! over ocean areas of the GV sites, are within +/- 10% of the Version 5 GV estimates at least over open Ocean areas, away from contaminating effects of land and coastal regions