Bernal and the structure of water

Bernal recognised early on the importance of water in biological systems and processes, and hence the need to understand the structure of the liquid if he was to understand its biological functionality. Although the structure of crystalline ice had been solved only a few years earlier, and little was understood about the structures of liquids in general, in 1933 he published what is still regarded as a seminal paper which treated not only the structure of liquid water itself, but also addressed an impressively wide range of problems of ice and ionic solutions. Imaginatively exploiting ideas that were developing at the time, he proposed a model for water that reproduced the main features of its x-ray diffraction pattern. Despite the success of this model, however, he subsequently found it unsatisfactory – ''a delusive approach, postulating a greater degree of order in the liquid than actually exists there''. Building on the very successful ''random packing'' model of simple liquids that he developed in the 1950s and 60s, he was ultimately led to a ''random network'' model that was consistent with the known properties of the individual water molecules, and that again could reproduce a range of experimental data – but this time without the model being too ordered. Todays state of the art experiments essentially verify the underlying validity of his ideal model. And even his 1933 model of the water molecule itself is mimicked in some of the more successful molecular models used in todays computer simulations of aqueous systems

Extracorporeal support for patients with acute respiratory distress syndrome.

Extracorporeal membrane oxygen (ECMO) has been used for many years in patients with life-threatening hypoxaemia and/or hypercarbia. While early trials demonstrated that it was associated with poor outcomes and extensive haemorrhage, the technique has evolved. It now encompasses new technologies and understanding that the lung protective mechanical ventilation it can facilitate is inextricably linked to improving outcomes for patients. The positive results from the CESAR (Conventional ventilation or ECMO for Severe Adult Respiratory failure) study and excellent outcomes in patients who suffered severe influenza A (H1N1/09) infection have established ECMO in the care of patients with severe acute respiratory distress syndrome. Controversy remains as to at what point in the clinical pathway ECMO should be employed; as a rescue therapy or more pro-actively to enable and ensure high-quality lung protective mechanical ventilation. The primary aims of this article are to discuss: 1) the types of extracorporeal support available; 2) the rationale for its use; 3) the relationship with lung protective ventilation; and 4) the current evidence for its use

Relationships Among Beef Cow Productivity Traits and Single Nucleotide Polymorphisms in the Bovine Heat Shock Protein 70 Gene

When eukaryotes are exposed to stressors such as heat, toxins, and low oxygen levels, heat shock proteins (HSPs) are synthesized to maintain normal cellular function within the body. Single nucleotide polymorphisms in the heat shock protein 70 (Hsp70) gene have been associated with calving percentage, and Julian calving date in spring-calving crossbred Brahman cows (Rosenkrans, et al., 2010). Our objective was to determine associations between previously identified polymorphisms in the promoter region and coding sequence of the bovine Hsp70 gene and beef cow efficiency. We evaluated productivity traits, including Julian calving date and calving rates, of fall-calving cows at each single nucleotide polymorphism (SNP) site. Genomic DNA was extracted from blood samples collected from crossbred cows (n=109) and amplified by polymerase chain reaction (PCR) using specific forward and reverse primers. Upon amplification, samples were purified, quantified, and sequenced in a commercial laboratory. Sequences were analyzed to determine SNP and genotypes were assigned to each of them. Production data of the cows from 2012-2014 were analyzed at each SNP site. Cows with CD genotype at C895D calved about one week later (P = 0.0001) and tended (P \u3c 0.06) to have calves with lighter birth weights compared to cows with CC genotype. Genotype at G2033C affected (P \u3c 0.02) weaning weight and cow efficiency. Genotype of a haplotype composite (No SNP, Deletion, and Yes SNP) affected (P \u3c 0.02) Julian date and cow efficiency. Polymorphisms associated with the bovine Hsp70 gene were related to important cattle productivity characteristics. Selecting replacement cattle with known Hsp70 genotypes may result in herds that are more thermotolerant and sustainable

An Empirical Test of Urban Labor Matching

This study tests for the labor matching efficiency of cities by examining the relationship between urbanization and the skills variation of public school principals. The results imply urban labor markets are generally more efficient at matching the skills of residents to the skills required by employers. The variation in labor skills among school principals is found to decrease with urban size, which is evidence that urbanization fosters more efficient labor matches.

Comment

This report describes a fourth order tensor defined on projective spaces which can be used for the representation of medium-level features, e.g., one or more oriented segments. The tensor has one part which describes what type of local structures are present in a region, and one part which describes where they are located. This information can be used, e.g., to represent multiple orientations, corners, and line-endings. The tensor can be defined for arbitrary signal dimension, but the presentation focuses on the properties of the fourth order tensor for the case of 2D and 3D image data. A method for estimating the proposed tensor representation by means of simple computations directly from the structure tensor is presented. Given a simple matrix representation of the tensor, it can be shown that there is a direct correspondence between the number of oriented segments and the rank of the matrix provided that the number of segments is three or less. The \publication also presents techniques for extracting information about the oriented segments which the tensor represent. Finally, it shown that a small set of coefficients can be computed from the proposed tensor which are invariant to changes of the coordinate system

Impacts of sociopolitical conditions

Space development scenarios and the choice of technologies to carry them out depend upon the future social, economic, and political factors. A brief discussion concerning the impact of sociopolitical conditions on space exploration is presented. Some of the topics mentioned include: space weapons/warfare, international cooperation, NASA's Search for Extraterrestrial Intelligence (SETI) Program, and superpower rivelry