A discussion of observation model, error sources and signal size for spaceborne gravitational gradiometry

Various space concepts were discussed during the past 20 years for a global improvement of the knowledge of the earth's gravity field. The concepts reach from high-low and low-low satellite-to-satellite tracking via tethered satellite gradiometers to sophisticated superconducting gradiometers. The purpose is to show that starting from one basic equation three criteria are sufficient to typify the various concepts and define the underlying observation model. Furthermore the different error sources, in particular, the time varying part of self-gravitation, and the expected signal size of all six gravity gradient components shall be discussed

Depositional Ice Nucleation onto Hydrated NaCl Particles: a New Mechanism for Ice Formation in the Troposphere

Sea-salt aerosol particles (SSA) are ubiquitous in the marine boundary layer and over coastal areas. Therefore SSA have ability to directly and indirectly affect the Earth’s radiation balance. The influence SSA have on climate is related to their water uptake and ice nucleation characteristics. In this study, optical microscopy coupled with Raman spectroscopy was used to detect the formation of an NaCl hydrate that could form under atmospheric conditions. NaCl(s) particles deliquesced at the well established value of 75.7±2.5% RH. NaCl(aq) particles effloresced to a mixture of hydrated and non-hydrated particles at temperatures between 236 and 252 K. The aqueous particles effloresced into the non-hydrated form at temperatures warmer than 252K. At temperatures colder than 236 K all particles effloresced into the hydrated form. The deliquescence relative humidities (DRH) of hydrated NaCl(s) particles ranged from 76.6 to 93.2% RH. Based on the measured DRH and efflorescence relative humidities (ERH), we estimate crystalline NaCl particles could be in the hydrated form 40–80% of the time in the troposphere. Additionally, the ice nucleating abilities of NaCl(s) and hydrated NaCl(s) were determined at temperatures ranging from 221 to 238 K. NaCl(s) particles depositionally nucleated ice at an average Sice value of 1.11±0.07. Hydrated NaCl(s) particles depositionally nucleated ice at an average Sice value of 1.02±0.04. When a mixture of hydrated and anhydrous NaCl(s) particles was present in the same sample, ice preferentially nucleated on the hydrated particles 100% of the time. While both types of particles are efficient ice nuclei, hydrated NaCl(s) particles are better ice nuclei than NaCl(s) particles

Depositional Ice Nucleation onto Hydrated NaCl Particles: A New Mechanism for Ice Formation in the Troposphere

Sea-salt aerosol (SSA) particles are ubiquitous in the marine boundary layer and over coastal areas. Therefore SSA have ability to directly and indirectly affect the Earth\u27s radiation balance. The influence SSA have on climate is related to their water uptake and ice nucleation characteristics. In this study, optical microscopy coupled with Raman spectroscopy was used to detect the formation of a crystalline NaCl hydrate that could form under atmospheric conditions. NaCl(s) particles (~1 to 10 μm in diameter) deliquesced at 75.7 ± 2.5% RH which agrees well with values previously established in the literature. NaCl(aq) particles effloresced to a mixture of hydrated and non-hydrated particles at temperatures between 236 and 252 K. The aqueous particles effloresced into the non-hydrated form at temperatures warmer than 252 K. At temperatures colder than 236 K all particles effloresced into the hydrated form. The deliquescence relative humidities (DRH) of hydrated NaCl(s) particles ranged from 76.6 to 93.2% RH. Based on the measured DRH and efflorescence relative humidities (ERH), we estimate crystalline NaCl particles could be in the hydrated form 40–80% of the time in the troposphere. Additionally, the ice nucleating abilities of NaCl(s) and hydrated NaCl(s) were determined at temperatures ranging from 221 to 238 K. Here, depositional ice nucleation is defined as the onset of ice nucleation and represents the conditions at which the first particle on the substrate nucleated ice. Thus the values reported here represent the lower limit of depositional ice nucleation. NaCl(s) particles depositionally nucleated ice at an average Sice value of 1.11 ± 0.07. Hydrated NaCl(s) particles depositionally nucleated ice at an average Sice value of 1.02 ± 0.04. When a mixture of hydrated and anhydrous NaCl(s) particles was present in the same sample, ice preferentially nucleated on the hydrated particles 100% of the time. While both types of particles are efficient ice nuclei, hydrated NaCl(s) particles are better ice nuclei than NaCl(s) particles

Detection of selection signatures in farmed coho salmon (Oncorhynchus kisutch) using dense genome-wide information

Animal domestication and artificial selection give rise to gradual changes at the genomic level in populations. Subsequent footprints of selection, known as selection signatures or selective sweeps, have been traced in the genomes of many animal livestock species by exploiting variation in linkage disequilibrium patterns and/or reduction of genetic diversity. Domestication of most aquatic species is recent in comparison with land animals, and salmonids are one of the most important fish species in aquaculture. Coho salmon (Oncorhynchus kisutch), cultivated primarily in Chile, has been subjected to breeding programs to improve growth, disease resistance traits, and flesh color. This study aimed to identify selection signatures that may be involved in adaptation to culture conditions and traits of productive interest. To do so, individuals of two domestic populations cultured in Chile were genotyped with 200 thousand SNPs, and analyses were conducted using iHS, XP-EHH and CLR. Several signatures of selection on different chromosomal regions were detected across both populations. Some of the identified regions under selection contained genes such anapc2, alad, chp2 and myn, which have been previously associated with body weight in Atlantic salmon, or sec24d and robo1, which have been associated with resistance to Piscirickettsia salmonis in coho salmon. Findings in our study can contribute to an integrated genome-wide map of selection signatures, to help identify the genetic mechanisms of phenotypic diversity in coho salmon

Spin accumulation and spin relaxation in a large open quantum dot

We report electronic control and measurement of an imbalance between spin-up and spin-down electrons in micron-scale open quantum dots. Spin injection and detection were achieved with quantum point contacts tuned to have spin-selective transport, with four contacts per dot for realizing a nonlocal spin-valve circuit. This provides an interesting system for studies of spintronic effects since the contacts to reservoirs can be controlled and characterized with high accuracy. We show how this can be used to extract in a single measurement the relaxation time for electron spins inside a ballistic dot (tau(sf) approximate to 300 ps) and the degree of spin polarization of the contacts (P approximate to 0.8).</p

Nuclear morphometric features in benign breast tissue and risk of subsequent breast cancer

Certain nuclear morphometric features measured in breast tumor tissue have been shown to predict the prognosis of breast cancer patients. However, the application of these features to predicting risk of breast cancer development has received little attention. We conducted a case-control study to evaluate nuclear morphometric features in benign breast tissue in association with subsequent breast cancer risk. The study was nested within a cohort of 4,888 women with a histopathologic diagnosis of benign breast disease (BBD) and involved 61 cases and 71 controls, amongst whom there were 53 matched case-control sets. Conditional logistic regression models were fitted to assess various measurements of nuclear size and nuclear shape factors in relation to subsequent breast cancer risk. In multivariate analysis, subsequent breast cancer risk was positively associated with a nuclear shape factor that takes the shortest nuclear axis and the longest nuclear axis into consideration simultaneously (highest quartile versus lowest 3 quartiles: odds ratio = 3.07, 95% confidence limits = 1.61, 5.84). In contrast, there was no alteration in subsequent breast cancer risk in association with nuclear size features and other shape factors. In conclusion, our study results suggest that the shape factor that takes both the shortest nuclear axis and the longest nuclear axis into consideration might be of value to predict subsequent development of breast cancer among women with BBD