A comparative molecular dynamics study of diffusion of n-decane and 3-methyl pentane in Y zeolite

Molecular dynamics simulations are reported on the structure and dynamics of n-decane and 3-methylpentane in zeolite NaY. We have calculated several properties such as the center of mass-center of mass rdf, the end-end distance distribution, bond angle distribution and dihedral angle distribution. We have also analysed trajectory to obtain diffusivity and velocity autocorrelation function (VACF). Surprisingly, the diffusivity of 3-methylpentane which is having larger cross-section perpendicular to the long molecular axis is higher than n-decane at 300 K. Activation energies have been obtained from simulations performed at 200 K, 300 K, 350 K, 400 K and 450 K in the NVE ensemble. These results can be understood in terms of the previously known levitation effect. Arrhenious plot has higher value of slope for n-decane (5 center dot 9 kJ/mol) than 3-methylpentane (3 center dot 7 kJ/mol) in agreement with the prediction of levitation effect.

Hormone therapy in elderly women; a comparative study with alendronate of the effects on bone, cardiovascular risk factors, periodontal conditions and quality of life

Thirty percent of 70-year-old women have osteoporosis; after age of 80 its prevalence is up to 70%. Postmenopausal women with osteoporosis seem to be at an increased risk for cardiovascular events, and deterioration of oral health, as shown by attachment loss of teeth, which is proportional to the severity of osteoporosis. Osteoporosis can be treated with many different medication, e.g. estrogen and alendronate. We randomized 90 elderly osteoporotic women (65-80 years of age) to receive hormone therapy (HT)(2mg E2+NETA), 10mg alendronate, and their combination for two years and compared their effects on bone mineral density (BMD) and turnover, two surrogate markers of the risk of cardiovascular diseases, C-reactive protein (CRP) and E-selectin, as well as oral health. The effect of HT on health-related quality of life (HRQoL) was studied in the population-based cohort of 1663 postmenopausal women (mean age 68 yr) (585 estrogen users and 1078 non-users). BMD was measured with dual-energy X-ray absorptiometry (DXA) at 0, 12 and 24 months. Urinary N-telopeptide (NTX) of type I collagen, a marker of bone resorption, and serum aminoterminal propeptide of human type I procollagen (PINP), a marker of bone formation, were measured every six months of treatment. Serum CRP and E-selectin, were measured at 0, 6, and 12 months. Dental, and periodontal conditions, and gingival crevicular fluid (GCF) matrix metalloproteinase (MMP)-8 levels were studied to evaluate the oral health status and for the mouth symptoms a structured questionnaire was used. The HRQoL was measured with 15D questionnaire. Lumbar spine BMD increased similarly in all treatment groups (6.8-8.4% and 9.1-11.2%). Only HT increased femoral neck BMD at both 12 (4.9%) and 24 months (5.8%), at the latter time point the HT group differed significantly from the other groups. HT reduced bone marker levels of NTX and PINP significantly less than other two groups.Oral HT significantly increased serum CRP level by 76.5% at 6 and by 47.1% (NS) at 12 months, and decreased serum E-selectin level by 24.3% and 30.0%. Alendronate had no effect on these surrogate markers. Alendronate caused a decrease in the resting salivary flow rate and tended to increase GCF MMP-8 levels. Otherwise, there was no effect on the parameters of oral health. HT improved the HRQoL of elderly women significantly on the dimensions of usual activities, vitality and sexual activity, but the overall improvement in HRQoL was neither statistically significant nor clinically important. In conclusion, bisphosphonates might be the first option to start the treatment of postmenopausal osteoporosis in the old age.

'Mutiny on the Bounty': The genetic history of Norfolk Island reveals extreme gender-biased admixture

Background The Pacific Oceania region was one of the last regions of the world to be settled via human migration. Here we outline a settlement of this region that has given rise to a uniquely admixed population. The current Norfolk Island population has arisen from a small number of founders with mixed Caucasian and Polynesian ancestry, descendants of a famous historical event. The ‘Mutiny on the Bounty’ has been told in history books, songs and the big screen, but recently this story can be portrayed through comprehensive molecular genetics. Written history details betrayal and murder leading to the founding of Pitcairn Island by European mutineers and the Polynesian women who left Tahiti with them. Investigation of detailed genealogical records supports historical accounts. Findings Using genetics, we show distinct maternal Polynesian mitochondrial lineages in the present day population, as well as a European centric Y-chromosome phylogeny. These results comprehensively characterise the unique gender-biased admixture of this genetic isolate and further support the historical records relating to Norfolk Island. Conclusions Our results significantly refine previous population genetic studies investigating Polynesian versus Caucasian diversity in the Norfolk Island population and add information that is beneficial to future disease and gene mapping studies.

Low-lying states of transverse substituted trans-polyacetylene and trans-polyacetylene: A comparative DMRG study

The density-matrix renormalization group (DMRG) method is used for a comparative study of low-lying excitations in trans-polyacetylene (t-PA) and transversely substituted t-PA (TS-t-PA). We have employed the Pariser-Parr-Pople model Hamiltonian which incorporates long-range electronic correlations to model these systems. We find some fundamental differences in the excited states of the t-PA and TS-t-PA. We find that the lowest two-photon allowed excited state in TS-t-PA is not made up of two triplet excitons and the gap to this state is nonzero even for undimerized chains in the thermodynamic limit. Contrary to earlier results for the Hubbard model, we find that the lowest two-photon state is always below the first optically allowed state in all the systems studied here making TS-t-PA systems only weakly fluorescent materials. Nonresonant tumbling averaged linear and third harmonic generation optic coefficients of TS-t-PA systems are also much smaller than that of t-PA.

History and development of public health

This chapter and the others that follow have the study of population health as their focus, as opposed to a focus on individual care and treatment. Clearly, however, we are concerned with the way in which population health is influenced by biomedical theories and practices, and the way population health is funded, and is influenced by the importance placed on therapeutic medicine. The discussions that follow include a brief overview of the ancient history of public health, and the modern history of Western public health dating from 1850. This date signifies the beginnings of a more organised, collective effort to protect the public’s health. These discussions will help you further expand your definition of public health. You will have an entertaining journey through public health achievements, and less successful outcomes, by examining the historical developments that have led us to a modern understanding of public health. The ancient Greeks and Romans, for example, had public health measures to ensure the safety and health of their populations, for a range of social and economic reasons. Convicts arrived in Australia with many health problems, and were put to work to satisfy the needs of a fledgling colony. It is important to understand the historical journey of public health and the way it is critically analysed, as it provides a looking-glass onto the present and the future.