THE BEHAVIOR OF ELECTROLYTIC SOLUTIONS AT ELEVATED TEMPERATURES AS DERIVED FROM CONDUCTANCE MEASUREMENTS

Methods and techniques for measuring the conductances of reactor solutions at elevated temperatures and to interpret the results with electrolytic solution theories are discussed. Criteria applied to room-temperature conductances for determining complete ionization of 1-1 electrolytes were applied to the Noyes high-temperature conductance data obtdined on NaCl, HCl, KCl, NaOH, AgNO3, and H/sub 3/PO/sub 4/ solutions. lt was found that the first four electrolytes behave as strong electrolytes up through temperatures of 218, 218, 281, and 156 deg C, respectively. Application of the Bjerrum theory showed that, somewhat above each of these temperatures, these electrolytes begin to associate by ion-pair formation. H/sub 3/PO/sub 4/ solutions associated at room temperature and above. AgNO/sub 3/ solutions appeared to asscciate at all temperatures. The equivalent conductances and infinite dilution and the dissociation constants for each of the electrolytes were calculatsd. An apparatus was constructed and measurements were made on the conductances of LiOH and NH/sub 4/OH solutions over the temperature range of 100 to 520 deg F. Equivalent conductances at infinite dilution were calculated. The pH of reactor coolants using LiOH or NH/sub 4/OH was calculated from the disscciation constants for water, LiOH, and NH/sub 4/OH at elevated temperatures. (auth

THE PERFORMANCE OF BASE-FORM ION EXCHANGERS FOR pH CONTROL AND REMOVAL OF RADIOISOTOPES FROM A PRESSURIZED WATER REACTOR SYSTEM

Laboratory experiments and in-pile loop tests designed to evaluate, explain, and predict the performance of mixedbed ion exchange columns in the base form for the control of radioisotopes in reactor coolants are summarized. The results of these tests are evaluated with the aid of a simple theory of column performance for absorption of radioactivity decaying ions, based on an approximate model for an ion exchange column. It is concluded that LiOH form resin will perform satisfactorily for both pH control and activity removal and that it is more effective than either KOH resin or NH/sub 4/OH resin for these purposes. (auth

Using clinical risk factors and bone mineral density to determine who among patients undergoing bone densitometry should have vertebral fracture assessment

Vertebral fracture assessment (VFA) is a new method for imaging thoracolumbar spine on bone densitometer. Among patients referred for bone densitometry, the selection of patients for VFA testing can be optimized using an index derived from clinical risk factors and bone density measurement. VFA, a method for imaging thoracolumbar spine on bone densitometer, was developed because vertebral fractures, although common and predictive of future fractures, are often not clinically diagnosed. The study objective was to develop a strategy for selecting patients for VFA. A convenience sample from a university hospital bone densitometry center included 892 subjects (795 women) referred for bone mineral density (BMD) testing. We used questionnaires to capture clinical risk factors and dual-energy X-ray absorptiometry to obtain BMD and VFA. Prevalence of vertebral fractures was 18% in women and 31% in men (p = 0.003 for gender difference). In women, age, height loss, glucocorticoid use, history of vertebral and other fractures, and BMD T-score were significantly and independently associated with vertebral fractures. A multivariate model which included above predictors had an area under the receiver operating curve of 0.85 with 95% confidence interval (CI) of 0.81 to 0.89. A risk factor index was derived from the above multivariate model. Using a level of 2 as a cut-off yielded 93% sensitivity (95% CI 87, 96) and 48% specificity (95% CI 69, 83). Assuming a 15% prevalence of vertebral fractures, this cut-off value had a 24% positive and 97% negative predictive value and required VFA scanning of three women at a cost of $60 (assuming a$20 cost/VFA scan) to detect one with vertebral fracture(s). Selecting patients for VFA can be optimized using an index derived from BMD measurement and easily obtained clinical risk factors

Potential climatic transitions with profound impact on Europe

We discuss potential transitions of six climatic subsystems with large-scale impact on Europe, sometimes denoted as tipping elements. These are the ice sheets on Greenland and West Antarctica, the Atlantic thermohaline circulation, Arctic sea ice, Alpine glaciers and northern hemisphere stratospheric ozone. Each system is represented by co-authors actively publishing in the corresponding field. For each subsystem we summarize the mechanism of a potential transition in a warmer climate along with its impact on Europe and assess the likelihood for such a transition based on published scientific literature. As a summary, the ‘tipping’ potential for each system is provided as a function of global mean temperature increase which required some subjective interpretation of scientific facts by the authors and should be considered as a snapshot of our current understanding. <br/

Integrating transposable elements in the 3D genome

Chromosome organisation is increasingly recognised as an essential component of genome regulation, cell fate and cell health. Within the realm of transposable elements (TEs) however, the spatial information of how genomes are folded is still only rarely integrated in experimental studies or accounted for in modelling. Whilst polymer physics is recognised as an important tool to understand the mechanisms of genome folding, in this commentary we discuss its potential applicability to aspects of TE biology. Based on recent works on the relationship between genome organisation and TE integration, we argue that existing polymer models may be extended to create a predictive framework for the study of TE integration patterns. We suggest that these models may offer orthogonal and generic insights into the integration profiles (or "topography") of TEs across organisms. In addition, we provide simple polymer physics arguments and preliminary molecular dynamics simulations of TEs inserting into heterogeneously flexible polymers. By considering this simple model, we show how polymer folding and local flexibility may generically affect TE integration patterns. The preliminary discussion reported in this commentary is aimed to lay the foundations for a large-scale analysis of TE integration dynamics and topography as a function of the three-dimensional host genome

Evaluation of alternative mosquito sampling methods for malaria vectors in Lowland South - East Zambia.

Sampling malaria vectors and measuring their biting density is of paramount importance for entomological surveys of malaria transmission. Human landing catch (HLC) has been traditionally regarded as a gold standard method for surveying human exposure to mosquito bites. However, due to the risk of human participant exposure to mosquito-borne parasites and viruses, a variety of alternative, exposure-free trapping methods were compared in lowland, south-east Zambia. Centres for Disease Control and Prevention miniature light trap (CDC-LT), Ifakara Tent Trap model C (ITT-C), resting boxes (RB) and window exit traps (WET) were all compared with HLC using a 3 × 3 Latin Squares design replicated in 4 blocks of 3 houses with long lasting insecticidal nets, half of which were also sprayed with a residual deltamethrin formulation, which was repeated for 10 rounds of 3 nights of rotation each during both the dry and wet seasons. The mean catches of HLC indoor, HLC outdoor, CDC-LT, ITT-C, WET, RB indoor and RB outdoor, were 1.687, 1.004, 3.267, 0.088, 0.004, 0.000 and 0.008 for Anopheles quadriannulatus Theobald respectively, and 7.287, 6.784, 10.958, 5.875, 0.296, 0.158 and 0.458, for An. funestus Giles, respectively. Indoor CDC-LT was more efficient in sampling An. quadriannulatus and An. funestus than HLC indoor (Relative rate [95% Confidence Interval] = 1.873 [1.653, 2.122] and 1.532 [1.441, 1.628], respectively, P < 0.001 for both). ITT-C was the only other alternative which had comparable sensitivity (RR = 0.821 [0.765, 0.881], P < 0.001), relative to HLC indoor other than CDC-LT for sampling An. funestus. While the two most sensitive exposure-free techniques primarily capture host-seeking mosquitoes, both have substantial disadvantages for routine community-based surveillance applications: the CDC-LT requires regular recharging of batteries while the bulkiness of ITT-C makes it difficult to move between sampling locations. RB placed indoors or outdoors and WET had consistently poor sensitivity so it may be useful to evaluate additional alternative methods, such as pyrethrum spray catches and back packer aspirators, for catching resting mosquitoes

Genomic DNA Pooling Strategy for Next-Generation Sequencing-Based Rare Variant Discovery in Abdominal Aortic Aneurysm Regions of Interest—Challenges and Limitations

The costs and efforts for sample preparation of hundreds of individuals, their genomic enrichment for regions of interest, and sufficient deep sequencing bring a significant burden to next-generation sequencing-based experiments. We investigated whether pooling of samples at the level of genomic DNA would be a more versatile strategy for lowering the costs and efforts for common disease-associated rare variant detection in candidate genes or associated loci in a substantial patient cohort. We performed a pilot experiment using five pools of 20 abdominal aortic aneurysm (AAA) patients that were enriched on separate microarrays for the reported 9p21.3 associated locus and 42 additional AAA candidate genes, and sequenced on the SOLiD platform. Here, we discuss challenges and limitations connected to this approach and show that the high number of novel variants detected per pool and allele frequency deviations to the usually highly false positive cut-off region for variant detection in non-pooled samples can be limiting factors for successful variant prioritization and confirmation. We conclude that barcode indexing of individual samples before pooling followed by a multiplexed enrichment strategy should be preferred for detection of rare genetic variants in larger sample sets rather than a genomic DNA pooling strategy

HIV-1 Epidemic in the Caribbean Is Dominated by Subtype B

The molecular epidemiology of HIV-1 in the Caribbean has been described using partial genome sequencing; subtype B is the most common subtype in multiple countries. To expand our knowledge of this, nearly full genome amplification, sequencing and analysis was conducted.Virion RNA from sera collected in Haiti, Dominican Republic, Jamaica and Trinidad and Tobago were reverse transcribed, PCR amplified, sequenced and phylogenetically analyzed. Nearly full genomes were completed for 15 strains; partial pol was done for 67 strains. All but one of the 67 strains analyzed in pol were subtype B; the exception was a unique recombinant of subtypes B and C collected in the Dominican Republic. Of the nearly full genomes of 14 strains that were subtype B in pol, all were subtype B from one end of the genome to the other and not inter-subtype recombinants. Surprisingly, the Caribbean subtype B strains clustered significantly with each other and separate from subtype B from other parts of the pandemic.The more complete analysis of HIV-1 from 4 Caribbean countries confirms previous research using partial genome analysis that the predominant subtype in circulation was subtype B. The Caribbean strains are phylogenetically distinct from other subtype B strains although the biological meaning of this finding is unclear

Fifteen new risk loci for coronary artery disease highlight arterial-wall-specific mechanisms

Coronary artery disease (CAD) is a leading cause of morbidity and mortality worldwide. Although 58 genomic regions have been associated with CAD thus far, most of the heritability is unexplained, indicating that additional susceptibility loci await identification. An efficient discovery strategy may be larger-scale evaluation of promising associations suggested by genome-wide association studies (GWAS). Hence, we genotyped 56,309 participants using a targeted gene array derived from earlier GWAS results and performed meta-analysis of results with 194,427 participants previously genotyped, totaling 88,192 CAD cases and 162,544 controls. We identified 25 new SNP-CAD associations (P &lt; 5 × 10(-8), in fixed-effects meta-analysis) from 15 genomic regions, including SNPs in or near genes involved in cellular adhesion, leukocyte migration and atherosclerosis (PECAM1, rs1867624), coagulation and inflammation (PROCR, rs867186 (p.Ser219Gly)) and vascular smooth muscle cell differentiation (LMOD1, rs2820315). Correlation of these regions with cell-type-specific gene expression and plasma protein levels sheds light on potential disease mechanisms