DMSP Poynting Flux: Data Processing and Inter-Spacecraft Comparisons.

Poynting flux (PF) calculated from low Earth orbit spacecraft in situ ion drift and magnetic field measurements is an important measure of energy exchange between the magnetosphere and ionosphere. Defense Meteorological Satellite Program (DMSP) spacecraft provide an extensive back-catalog of ion drift and magnetic perturbation measurements, from which quasi-steady PF could be calculated. However, since DMSP are operations-focused spacecraft, data must be carefully preprocessed for research use. We describe an automated approach for calculating earthward PF focusing on pre-processing and quality control. We produce a PF data set using nine satellite-years of DMSP F15, F16, and F18 observations. To validate our process we inter-compare PF from different spacecraft using more than 2,000 magnetic conjunction events. We find no serious systematic differences. We further describe and apply an equal-area binning technique to obtain average spatial patterns of PF, magnetic perturbation, electric field and ion drift velocity. We perform our analysis using all components of electric and magnetic field and comment on the adverse consequences of the typical single-electric-field-component DMSP PF approximation on inter-spacecraft agreement. Including full-field components significantly increases the relative strength of near-cusp PF and increases the integrated high-latitude PF by ∼25%.

Study on genetic structure differences and adjustment strategies in different areas of China / 中华流行病学杂志

Objective: To describe the genetic structure of populations in different areas of China, and explore the effects of different strategies to control the confounding factors of the genetic structure in cohort studies. Methods: By using the genome-wide association study (GWAS) on data of 4 500 samples from 10 areas of the China Kadoorie Biobank (CKB), we performed principal components analysis to extract the first and second principal components of the samples for the component two-dimensional diagram generation, and then compared them with the source of sample area to analyze the characteristics of genetic structure of the samples from different areas of China. Based on the CKB cohort data, a simulation data set with cluster sample characteristics such as genetic structure differences and extensive kinship was generated; and the effects of different analysis strategies including traditional analysis scheme and mixed linear model on the inflation factor (λ) were evaluated. Results: There were significant genetic structure differences in different areas of China. Distribution of the principal components of the population genetic structure was basically consistent with the geographical distribution of the project area. The first principal component corresponds to the latitude of different areas, and the second principal component corresponds to the longitude of different areas. The generated simulation data showed high false positive rate (λ=1.16), even if the principal components of the genetic structure was adjusted or the area specific subgroup analysis was performed, λ could not be effectively controlled (λ>1.05); while, by using a mixed linear model adjusting for the kinship matrix, λ was effectively controlled regardless of whether the genetic structure principal component was further adjusted (λ=0.99). Conclusions: There were large differences in genetic structure among populations in different areas of China. In molecular epidemiology studies, bias caused by population genetic structure needs to be carefully treated. For large cohort data with complex genetic structure and extensive kinship, it is necessary to use a mixed linear model for association analysis.

Water characteristics in cooked beef as influenced by ageing and high-pressure treatment-an NMR micro imaging study.

The water characteristics in cooked pressure-heat treated (45 °C for 45 min prior to pressurisation at 150 MPa for 30 min) and non-pressurised, cooked (control) samples of beef Longissimus aged for 1, 3, 8 or 16 days were studied by nuclear magnetic resonance microscopy. A multi-echo sequence was used to obtain T2 images, and independent of ageing period, the T2 values were found to be lower in pressure-heat treated meat revealing alterations in water characteristics of pressure-treated, cooked meat compared with cooked meat. With increasing ageing duration, the T2 values in both pressure-treated, cooked and cooked meat decreased indicating that the water became more tightly trapped in the protein network. In addition, independent of length of ageing period the relationship between cooking loss in the cooked meat and transverse relaxation differed between non-pressurised and pressure-treated meat, which reveals that the mechanisms changing the water properties in beef during ageing are different from those occuring during pressure-heat treatment of meat.

Ischaemic hepatitis in the elderly.

BACKGROUND: Ischaemic hepatitis is centrilobular necrosis which is usually associated with an acute cardiovascular event and in a general hospital setting has been considered to be a rare condition. It is though thought to be frequently unrecognized, which is important as it has implications for both investigations and drug therapy. Previous reports have not focused on the elderly. OBJECTIVES: (1) To determine the incidence of ischaemic hepatitis in elderly patients admitted to a Department of Geriatric Medicine and (2) to assess both the clinical and biochemical features of the condition. METHODS: 1,905 elderly patients (1,270 F, 635 M) admitted consecutively to our department over a 2-year period were assessed prospectively. All were aged > or =65 years (mean 78, range 65-98). Ischaemic hepatitis was diagnosed by a rapid development of abnormal liver function tests of hepatocellular type in acutely ill patients in whom a fall in blood pressure occurred and other causes of liver dysfunction were excluded. The admission, lowest and subsequent blood pressures were recorded. Daily renal and liver function tests, including prothrombin times, were measured during the acute illness. RESULTS: Nineteen patients (1%) developed ischaemic hepatitis. The clinical picture was dominated by the causal condition, the commonest being left ventricular failure (12 patients). The mean fall in systolic, diastolic and mean blood pressures were 61, 44 and 48 mm Hg, respectively. Within 3 days the alanine aminotransferase increased to more than 5 times normal and there were marked elevations of the lactic dehydrogenase. In those who survived, the liver enzymes returned to normal within 7-22 days (mean 13). The prothrombin time was prolonged to >20 s in 6 patients (32%). Six patients died, 5 from left ventricular failure; the mean creatinine in 5 of those who died was 244 micromol/l (range 174-355) and in each the urea was >25 micromol/l. CONCLUSION: Ischaemic hepatitis is an uncommon but not rare condition in elderly patients admitted acutely to a Department of Geriatric Medicine. There was a dramatic rise in liver enzymes which in survivors returned to normal within 3 weeks. Clinical features were dominated by the causal condition and a third of the patients died.