DYPHORA—a dynamic model for the rate of photosynthesis of algae

Experimental data obtained from different cultures of phytoplankton indicate that photosynthesis (P) depends on light intensity (I) in a dynamic way. Therefore, static P/I curves relating photosynthesis to the instantaneous light may not be adequate to describe the activity of algal cells in lakes or oceans where mixing can cause a complex pattern of light variation. The model DYPHORA (DYnamic model for the PHOtosynthetic Rate of Algae) describes the response of photosynthesis to light using two characteristic times, the response time to increasing light (τr), and the light inhibition decay time (τr). The model agrees well with available experiments if τr is chosen between 0.5 and 5 min, and τr, between 30 and 120 min. It explains the occurrence of the well-documented afternoon depression as well as the decrease of integrated long-term rates of photosynthesis with increasing light. Although the presented comparison of experimental data and model results cannot serve as a proof for DYPHORA in a strict sense, the structural relationship between P and I can nevertheless point out inadequacies in the common interpretation of static P/I relationships. The model can also serve as a tool to test hypotheses regarding the selective role of mixing in the competition between algal specie

Variability of Objectively Measured Sedentary Behavior

The primary purpose of this study was to evaluate variability of sedentary behavior (SB) throughout a 7-d measurement period and to determine if G7 d of SB measurement would be comparable with the typical 7-d measurement period. Methods: Retrospective data from Ball State University_s Clinical Exercise Physiology Laboratory on 293 participants (99 men, 55 T 14 yr, body mass index = 29 T 5 kgImj2; 194 women, 51 T 12 yr, body mass index = 27 T 7 kgImj2) with seven consecutive days of data collected with ActiGraph accelerometers were analyzed (ActiGraph, Fort Walton Beach, FL). Time spent in SB (either G100 counts per minute or G150 counts per minute) and breaks in SB were compared between days and by sex using a two-way repeated-measures ANOVA. Stepwise regression was performed to determine if G7 d of SB measurement were comparable with the 7-d method, using an adjusted R2 of Q0.9 as a criterion for equivalence. Results: There were no differences in daily time spent in SB between the 7 d for all participants. However, there was a significant interaction between sex and days, with women spending less time in SB on both Saturdays and Sundays than men when using the 100 counts per minute cut-point. Stepwise regression showed using any 4 d would be comparable with a 7-d measurement (R2 9 0.90). Conclusions: When assessed over a 7-d measurement period, SB appears to be very stable from day to day, although there may be some small differences in time spent in SB and breaks in SB between men and women, particularly on weekend days. The stepwise regression analysis suggests that a measurement period as short as 4 d could provide comparable data (91% of variance) with a 1-wk assessment. Shorter assessment periods would reduce both researcher and subject burden in data collection

Splotch: Visualizing Cosmological Simulations

We present a light and fast, public available, ray-tracer {\tt Splotch} software tool which supports the effective visualization of cosmological simulations data. We describe the algorithm it relies on, which is designed in order to deal with point-like data, optimizing the ray-tracing calculation by ordering the particles as a function of their ``depth'' defined as a function of one of the coordinates or other associated parameter. Realistic three-dimensional impressions are reached through a composition of the final color in each pixel properly calculating emission and absorption of individual volume elements. We describe several scientific as well as public applications realized with {\tt Splotch}. We emphasize how different datasets and configurations lead to remarkable different results in terms of the images and animations. A few of these results are available online.Comment: 19 Pages, 8 Figures, to appear in New Journal of Physics, Focus Issue on "Visualisation in Physics", edited by B. Sanders, T. Senden and V. Springe

High quality factor gigahertz frequencies in nanomechanical diamond resonators

We report actuation and detection of gigahertz-range resonance frequencies in nano-crystalline diamond mechanical resonators. High order transverse vibration modes are measured in coupled-beam resonators exhibiting frequencies up to 1.441 GHz. The cantilever-array design of the resonators translates the gigahertz-range resonant motion of micron-long cantilever elements to the displacement of the central supporting structure. Use of nano-crystalline diamond further increases the frequency compared to single crystal silicon by a factor of three. High clamping losses usually associated with micron-sized straight beams are suppressed in the periodic geometry of our resonators, allowing for high quality factors exceeding 20,000 above 500 MHz.Comment: 5 pages, two figures, one table, two-column format. Related papers can be found at http://nano.bu.edu

Efficacy of the nootropic supplement Mind Lab Pro on memory in adults: Double blind, placebo-controlled study

Objectives This study aimed to investigate the efficacy of taking Mind Lab Pro, a plant-based nootropic on memory in a group of healthy adults. Auditory, visual, visual working memory, immediate and delayed recall (DR) were assessed. Methods The study employed a pseudo randomised, double blinded, placebo-controlled design. A total of 49 healthy individuals completed the study with 36 in the experimental group and 13 in the control group. Participants ranged between 20 and 68 years with a mean age of 31.4 ± 14.4 years. Pre and post taking either the Mind Lab Pro supplement or placebo for 30 days. All participants completed the Wechsler Memory Scale Fourth UK Edition (WSM-IV UK). Results We found that the experimental group significantly improved in all memory subtests assessed (p < 0.05) whilst the control group only significantly improved in auditory memory and immediate recall (p = 0.004 and p = 0.014 respectively). A significant difference in immediate and DR was also found between the control and experimental group (p = 0.005 and 0.034 respectively). Conclusion The use of Mind Lab Pro for 4 weeks improves memory with the experimental group significantly improving in all sub areas of memory as assessed by the WSM-IV UK

Depression and cardiovascular disease are not linked by high blood pressure: findings from the SAPALDIA cohort

Depression and cardiovascular disease (CVD) are main contributors to the global disease burden and are linked. Pathophysiological pathways through increased blood pressure (BP) are a common focus in studies aiming to explain the relationship. However, studies to date have not differentiated between the predictive effect of depression on the course of BP versus hypertension diagnosis. Hence, we aimed to elucidate this relationship by incorporating these novel aspects in the context of a cohort study. We included initially normotensive participants (n = 3214) from the second (2001-2003), third (2009-2011), and fourth (2016-2018) waves of the Swiss Cohort Study on Air Pollution and Lung and Heart Diseases in Adults (SAPALDIA). We defined depression based on physician diagnosis, depression treatment and/or SF-36 Mental Health score < 50. The prospective association between depression and BP change was quantified using multivariable censored regression models, and logistic regression for the association between depression and incident hypertension diagnosis. All models used clustered robust standard errors to account for repeat measurements. The age-related increase in systolic BP was slightly lower among people with depression at baseline (beta = - 2.08 mmHg/10 years, 95% CI - 4.09 to - 0.07) compared to non-depressed. A similar trend was observed with diastolic BP (beta = - 0.88 mmHg/10 years, 95% CI - 2.15 to 0.39), albeit weaker and not statistically significant. Depression predicted the incidence of hypertension diagnosis (OR 1.86, 95% CI 1.33 to 2.60). Our findings do not support the hypothesis that depression leads to CVD by increasing BP. Future research on the role of depression in the pathway to hypertension and CVD is warranted in larger cohorts, taking into account healthcare utilization as well as medication for depression and hypertension

Perceived built environment, health-related quality of life and health care utilization

Previous research has shown that the built environment plays a crucial role for health-related quality of life (HRQoL) and health care utilization. But, there is limited evidence on the independence of this association from lifestyle and social environment. The objective of this cross-sectional study was to investigate these associations, independent of the social environment, physical activity and body mass index (BMI). We used data from the third follow-up of the Swiss study on Air Pollution and Lung and Heart diseases In Adults (SAPALDIA), a population based cohort with associated biobank. Covariate adjusted multiple quantile and polytomous logistic regressions were performed to test associations of variables describing the perceived built environment with HRQoL and health care utilization. Higher HRQoL and less health care utilization were associated with less reported transportation noise annoyance. Higher HRQoL was also associated with greater satisfaction with the living environment and more perceived access to greenspaces. These results were independent of the social environment (living alone and social engagement) and lifestyle (physical activity level and BMI). This study provides further evidence that the built environment should be designed to integrate living and green spaces but separate living and traffic spaces in order to improve health and wellbeing and potentially save health care costs

Air pollution and diabetes association : modification by type 2 diabetes genetic risk score

Exposure to ambient air pollution (AP) exposure has been linked to type 2 diabetes (T2D) risk. Evidence on the impact of T2D genetic variants on AP susceptibility is lacking. Compared to single variants, joint genetic variants contribute substantially to disease risk. We investigated the modification of AP and diabetes association by a genetic risk score (GRS) covering 63 T2D genes in 1524 first follow-up participants of the Swiss cohort study on air pollution and lung and heart diseases in adults. Genome-wide data and covariates were available from a nested asthma case-control study design. AP was estimated as 10-year mean residential particulate matter &lt;10μm (PM10). We computed count-GRS and weighted-GRS, and applied PM10 interaction terms in mixed logistic regressions, on odds of diabetes. Analyses were stratified by pathways of diabetes pathology and by asthma status. Diabetes prevalence was 4.6% and mean exposure to PM10 was 22μg/m(3). Odds of diabetes increased by 8% (95% confidence interval: 2, 14%) per T2D risk allele and by 35% (-8, 97%) per 10μg/m(3) exposure to PM10. We observed a positive interaction between PM10 and count-GRS on diabetes [ORinteraction=1.10 (1.01, 1.20)], associations being strongest among participants at the highest quartile of count-GRS [OR: 1.97 (1.00, 3.87)]. Stronger interactions were observed with variants of the GRS involved in insulin resistance [(ORinteraction=1.22 (1.00, 1.50)] than with variants related to beta-cell function. Interactions with count-GRS were stronger among asthma cases. We observed similar results with weighted-GRS. Five single variants near GRB14, UBE2E2, PTPRD, VPS26A and KCNQ1 showed nominally significant interactions with PM10 (P&lt;0.05). Our results suggest that genetic risk for T2D may modify susceptibility to air pollution through alterations in insulin sensitivity. These results need confirmation in diabetes cohort consortia