Northwestern University

About: Northwestern University is a education organization based out in Evanston, Illinois, United States. It is known for research contribution in the topics: Population & Transplantation. The organization has 75430 authors who have published 188857 publications receiving 9463252 citations. The organization is also known as: Northwestern & NU.

Orai1 is an essential pore subunit of the CRAC channel

Abstract: Stimulation of immune cells causes depletion of Ca2+ from endoplasmic reticulum (ER) stores, thereby triggering sustained Ca2+ entry through store-operated Ca2+ release-activated Ca2+ (CRAC) channels, an essential signal for lymphocyte activation and proliferation. Recent evidence indicates that activation of CRAC current is initiated by STIM proteins, which sense ER Ca2+ levels through an EF-hand located in the ER lumen and relocalize upon store depletion into puncta closely associated with the plasma membrane. We and others recently identified Drosophila Orai and human Orai1 (also called TMEM142A) as critical components of store-operated Ca2+ entry downstream of STIM. Combined overexpression of Orai and Stim in Drosophila cells, or Orai1 and STIM1 in mammalian cells, leads to a marked increase in CRAC current. However, these experiments did not establish whether Orai is an essential intracellular link between STIM and the CRAC channel, an accessory protein in the plasma membrane, or an actual pore subunit. Here we show that Orai1 is a plasma membrane protein, and that CRAC channel function is sensitive to mutation of two conserved acidic residues in the transmembrane segments. E106D and E190Q substitutions in transmembrane helices 1 and 3, respectively, diminish Ca2+ influx, increase current carried by monovalent cations, and render the channel permeable to Cs+. These changes in ion selectivity provide strong evidence that Orai1 is a pore subunit of the CRAC channel.

Galaxies on FIRE (Feedback In Realistic Environments): stellar feedback explains cosmologically inefficient star formation

Abstract: We present a series of high-resolution cosmological simulations of galaxy formation to z = 0, spanning halo masses ∼10^8–10^(13) M⊙, and stellar masses ∼10^4–10^(11) M⊙. Our simulations include fully explicit treatment of the multiphase interstellar medium and stellar feedback. The stellar feedback inputs (energy, momentum, mass, and metal fluxes) are taken directly from stellar population models. These sources of feedback, with zero adjusted parameters, reproduce the observed relation between stellar and halo mass up to M_(halo) ∼ 10^(12) M⊙. We predict weak redshift evolution in the M*–M_(halo) relation, consistent with current constraints to z > 6. We find that the M*–M_(halo) relation is insensitive to numerical details, but is sensitive to feedback physics. Simulations with only supernova feedback fail to reproduce observed stellar masses, particularly in dwarf and high-redshift galaxies: radiative feedback (photoheating and radiation pressure) is necessary to destroy giant molecular clouds and enable efficient coupling of later supernovae to the gas. Star formation rates (SFRs) agree well with the observed Kennicutt relation at all redshifts. The galaxy-averaged Kennicutt relation is very different from the numerically imposed law for converting gas into stars, and is determined by self-regulation via stellar feedback. Feedback reduces SFRs and produces reservoirs of gas that lead to rising late-time star formation histories, significantly different from halo accretion histories. Feedback also produces large short-time-scale variability in galactic SFRs, especially in dwarfs. These properties are not captured by common ‘sub-grid’ wind models.

Semiconductor ultraviolet detectors

Abstract: In this review article a comprehensive analysis of the developments in ultraviolet (UV) detector technology is described. At the beginning, the classification of UV detectors and general requirements imposed on these detectors are presented. Further considerations are restricted to modern semiconductor UV detectors, so the basic theory of photoconductive and photovoltaic detectors is presented in a uniform way convenient for various detector materials. Next, the current state of the art of different types of semiconductor UV detectors is presented. Hitherto, the semiconductor UV detectors have been mainly fabricated using Si. Industries such as the aerospace, automotive, petroleum, and others have continuously provided the impetus pushing the development of fringe technologies which are tolerant of increasingly high temperatures and hostile environments. As a result, the main efforts are currently directed to a new generation of UV detectors fabricated from wide band‐gap semiconductors the most promising ...

Angiotensin-Neprilysin inhibition in heart failure with preserved ejection fraction

Abstract: Background The angiotensin receptor–neprilysin inhibitor sacubitril–valsartan led to a reduced risk of hospitalization for heart failure or death from cardiovascular causes among patients ...

Restrained and unrestrained eating

Abstract: Nisbett's (1972) model of obesity implies that individual differences in relative deprivation (relative to set-point weight) within obese and normal weight groups should produce corresponding within-group differences in eating behavior. Normal weight subjects were separated into hypothetically deprived (high restraint) and non-deprived (low restraint) groups. The expectation that high restraint subjects' intake would vary directly with preload size while low restraint subjects would eat in inverse proportion to preload size, was confirmed. It was concluded that relative deprivation rather than obesity per se may be the cirtical determinant of individual differences in eating behavior. Consideration was given to the concept of "restraint" as an important behavioral mechanism affecting the expression of physiologically-based hungar.