Peristaltic Pumping of Blood Through Small Vessels of Varying Cross-section

The paper is devoted to a study of the peristaltic motion of blood in the micro-circulatory system. The vessel is considered to be of varying cross-section. The progressive peristaltic waves are taken to be of sinusoidal nature. Blood is considered to be a Herschel-Bulkley fluid. Of particular concern here is to investigate the effects of amplitude ratio, mean pressure gradient, yield stress and the power law index on the velocity distribution, streamline pattern and wall shear stress. On the basis of the derived analytical expression, extensive numerical calculations have been made. The study reveals that velocity of blood and wall shear stress are appreciably affected due to the non-uniform geometry of blood vessels. They are also highly sensitive to the magnitude of the amplitude ratio and the value of the fluid index.Comment: Accepted for publication in ASME journal of Applied Mechanics. arXiv admin note: text overlap with arXiv:1108.1285v

Free energy barrier for melittin reorientation from a membrane-bound state to a transmembrane state

An important step in a phospholipid membrane pore formation by melittin antimicrobial peptide is a reorientation of the peptide from a surface into a transmembrane conformation. In this work we perform umbrella sampling simulations to calculate the potential of mean force (PMF) for the reorientation of melittin from a surface-bound state to a transmembrane state and provide a molecular level insight into understanding peptide and lipid properties that influence the existence of the free energy barrier. The PMFs were calculated for a peptide to lipid (P/L) ratio of 1/128 and 4/128. We observe that the free energy barrier is reduced when the P/L ratio increased. In addition, we study the cooperative effect; specifically we investigate if the barrier is smaller for a second melittin reorientation, given that another neighboring melittin was already in the transmembrane state. We observe that indeed the barrier of the PMF curve is reduced in this case, thus confirming the presence of a cooperative effect

Quantification of Optic Disc Edema during Exposure to High Altitude Shows No Correlation to Acute Mountain Sickness

BACKGROUND: The study aimed to quantify changes of the optic nerve head (ONH) during exposure to high altitude and to assess a correlation with acute mountain sickness (AMS). This work is related to the Tuebingen High Altitude Ophthalmology (THAO) study. METHODOLOGY/PRINCIPAL FINDINGS: A confocal scanning laser ophthalmoscope (cSLO, Heidelberg Retina Tomograph, HRT3®) was used to quantify changes at the ONH in 18 healthy participants before, during and after rapid ascent to high altitude (4559 m). Slitlamp biomicroscopy was used for clinical optic disc evaluation; AMS was assessed with Lake Louise (LL) and AMS-cerebral (AMS-c) scores; oxygen saturation (SpO₂) and heart rate (HR) were monitored. These parameters were used to correlate with changes at the ONH. After the first night spent at high altitude, incidence of AMS was 55% and presence of clinical optic disc edema (ODE) 79%. Key stereometric parameters of the HRT3® used to describe ODE (mean retinal nerve fiber layer [RNFL] thickness, RNFL cross sectional area, optic disc rim volume and maximum contour elevation) changed significantly at high altitude compared to baseline (p<0.05) and were consistent with clinically described ODE. All changes were reversible in all participants after descent. There was no significant correlation between parameters of ODE and AMS, SpO₂ or HR. CONCLUSIONS/SIGNIFICANCE: Exposure to high altitude leads to reversible ODE in the majority of healthy subjects. However, these changes did not correlate with AMS or basic physiologic parameters such as SpO₂ and HR. For the first time, a quantitative approach has been used to assess these changes during acute, non-acclimatized high altitude exposure. In conclusion, ODE presents a reaction of the body to high altitude exposure unrelated to AMS

Influence of Apathy and Grit on Exercise Adherence for Persons with Parkinson’s Disease: A Cohort Study

Purpose: Parkinson’s disease (PD) is the second most common neurodegenerative disease in the United States. A preponderance of evidence supports exercise and physical activity as an effective intervention to slow the progression of motor symptoms in persons with PD. However, less study has been given to the influence of non-motor symptoms of PD, such as apathy and grit, on adherence to therapeutic exercise programs. The primary aim of this study was to characterize levels of apathy and grit in individuals with PD and explore any relationship to adherence in a community exercise program. Due to the importance of caregiver interaction, this study also examined the non-cognitive traits of caregivers of persons with PD. Methods: A descriptive cohort design was used and a convenience sample of individuals with Parkinson’s disease and their caregivers attending a Parkinson’s support group was collected. Results: A total of N=14 participants were included in this study. Levels of grit between persons with PD and caregiver demonstrated a weak positive correlation (rpb = 0.34, p = 0.23). No significant relationships were found between apathy and exercise attendance for PD (r = -0.10, p = 0.83), or among grit and exercise attendance (r = 0.24, p = 0.60). Levels of grit in PD was significantly and negatively related to apathy of caregivers (r = - 0.78, p = 0.04). Grit scores between caregivers and levels of apathy in persons with PD was significantly correlated (r = 0.84, p = 0.02). Findings suggest underlying relationships may exist between levels of grit, apathy, and adherence to exercise programs for persons with PD. Conclusion: Further research into the non-motor aspects of PD and their caregivers is warranted. The caregiver relationship plays a critical role in caring for persons with PD and may impact one’s adherence to therapeutic exercise

Characterization of dominant lactic acid bacteria isolated from São Jorge cheese, using biochemical and ribotyping methods

Aims: To identify, using phenotypic and genotypic methods, the dominant lactic acid bacteria (LAB) present in São Jorge cheese – one of the 11 Portuguese cheeses currently bearing an Appéllation d’Origine Protegée status. Methods and Results:  A total of 225 isolates from milk, curd and cheeses throughout ripening were identified to the genus level, 108 to the species level and ten to the strain level. Phenotypic methods indicated that lactobacilli, followed by enterococci, were the dominant bacteria. The most frequently isolated species were Lactobacillus paracasei, Lactobacillus rhamnosus, Enterococcus faecalis and Enterococcus faecium. Ribotyping differentiated three L. paracasei, two E. faecalis and one Lactobacillus plantarum types. Enterococcus spp. exhibited the highest esterase and β-galactosidase activities among all isolates. Conclusions:  The dominant LAB in São Jorge cheese are L. paracasei, L. rhamnosus, E. faecalis and E. faecium. Enterococcus likely plays a leading role upon acidification and aroma development in said cheese. Significance and Impact of the Study: Our results support that a combination of conventional biochemical methods with genotypic methods allows for a thorough characterization and identification of isolates. Despite the limited number of isolates subject to molecular subtyping, a few specific Enterococcus and Lactobacillus strains were found that are promising ones for development of a starter culture. Hence, L. paracasei and E. faecalis are good candidates for a tentative starter culture, designed for manufacturing of São Jorge cheese at large – which takes advantage of actual isolates, in attempts to eventually standardize the quality of said cheese variety

A Guide to Community Shared Solar: Utility, Private, and Non-Profit Project Development (Book)

This guide is organized around three sponsorship models: utility-sponsored projects, projects sponsored by special purpose entities - businesses formed for the purpose of producing community solar power, and non-profit sponsored projects. The guide addresses issues common to all project models, as well as issues unique to each model

A Guide to Community Shared Solar: Utility, Private, and Non-Profit Project Development (Book)

This guide is organized around three sponsorship models: utility-sponsored projects, projects sponsored by special purpose entities - businesses formed for the purpose of producing community solar power, and non-profit sponsored projects. The guide addresses issues common to all project models, as well as issues unique to each model