The StarScan plate measuring machine: overview and calibrations

The StarScan machine at the U.S. Naval Observatory (USNO) completed measuring photographic astrograph plates to allow determination of proper motions for the USNO CCD Astrograph Catalog (UCAC) program. All applicable 1940 AGK2 plates, about 2200 Hamburg Zone Astrograph plates, 900 Black Birch (USNO Twin Astrograph) plates, and 300 Lick Astrograph plates have been measured. StarScan comprises of a CCD camera, telecentric lens, air-bearing granite table, stepper motor screws, and Heidenhain scales to operate in a step-stare mode. The repeatability of StarScan measures is about 0.2 micrometer. The CCD mapping as well as the global table coordinate system has been calibrated using a special dot calibration plate and the overall accuracy of StarScan x,y data is derived to be 0.5 micrometer. Application to real photographic plate data shows that position information of at least 0.65 micrometer accuracy can be extracted from course grain 103a-type emulsion astrometric plates. Transformations between "direct" and "reverse" measures of fine grain emulsion plate measures are obtained on the 0.3 micrometer level per well exposed stellar image and coordinate, which is at the limit of the StarScan machine.Comment: 24 pages, 8 figures, accepted for PAS

A Radio--Optical Reference Frame VIII. CCD observations from KPNO and CTIO: internal calibration and first results

In this pilot investigation, precise optical positions in the FK5 system are presented for a set of 16 compact extragalactic radio sources, which will be part of the future radio--optical reference frame. The 0.9 m KPNO and CTIO telescopes equipped with 2K CCD's have been used for this project. The astrometric properties of these instruments are investigated in detail. New techniques of using wide field CCD observations for astrometry in general are developed. An internal precision of 5 to 31 mas in position per single exposure is found, depending on the brightness of the object. The tie to the primary optical reference system is established by photographic astrometry using dedicated astrographs on both hemispheres. An accuracy of $\approx 30$ mas per source is estimated for the multi--step reduction procedure when based on the future Hipparcos catalog, while the FK5--based positions suffer from system errors of 100 to 200 mas as compared to the radio positions. This work provides a contribution to the international effort to link the Hipparcos instrumental coordinate system to the quasi--inertial VLBI radio reference frame. Precise radio and optical astrometry of a large sample of compact extragalactic sources will also contribute to the astrophysics of these objects by comparing the respective centers of emission at the optical and radio wavelengths.Comment: AAS v.4 LaTeX, 2 parts on 1 file (main text + deluxetable), accepted by AJ, Dec.95, fig. with reprint

XMM Follow-Up Observations of Three Swift BAT-Selected Active Galactic Nuclei

We present XMM-Newton observations of three AGN taken as part of a hunt to find very heavily obscured Compton-thick AGN. For obscuring columns greater than 10^25 cm^-2, AGN are only visible at energies below 10 keV via reflected/scattered radiation, characterized by a flat power-law. We therefore selected three objects (ESO 417-G006, IRAS 05218-1212, and MCG -01-05-047) from the Swift BAT hard X-ray survey catalog with Swift X-ray Telescope XRT 0.5-10 keV spectra with flat power-law indices as candidate Compton-thick sources for follow-up observations with the more sensitive instruments on XMM-Newton. The XMM spectra, however, rule out reflection-dominated models based on the weakness of the observed Fe K-alpha lines. Instead, the spectra are well-fit by a model of a power-law continuum obscured by a Compton-thin absorber, plus a soft excess. This result is consistent with previous follow-up observations of two other flat-spectrum BAT-detected AGN. Thus, out of the six AGN in the 22-month BAT catalog with apparently flat Swift XRT spectra, all five that have had follow-up observations are not likely Compton-thick. We also present new optical spectra of two of these objects, IRAS 05218-1212 and MCG -01-05-047. Interestingly, though both these AGN have similar X-ray spectra, their optical spectra are completely different, adding evidence against the simplest form of the geometric unified model of AGN. IRAS 05218-1212 appears in the optical as a Seyfert 1, despite the ~8.5x10^22 cm^-2 line-of-sight absorbing column indicated by its X-ray spectrum. MCG -01-05-047's optical spectrum shows no sign of AGN activity; it appears as a normal galaxy.Comment: 18 pages including 4 figures, accepted by Ap

Facilitators and barriers to fitness bootcamp participation using the Behaviour Change Wheel

Objective: Despite its importance for mental and physical health, many adults fail to meet current physical activity recommendations. Furthermore, most adults who begin a physical activity programme revert to being less active or even inactive within the first 6 months. Fitness bootcamps represent a potential intervention for improving physical activity in healthy adults. However, no study to date has examined the influences on long-term participation in fitness bootcamps, which is the first step to developing an effective intervention. Using the Behaviour Change Wheel (BCW) framework, this study identified the facilitators and barriers to long-term (1 year or more) fitness bootcamp participation, which were then linked to behaviour change techniques (BCTs) to facilitate intervention development. Design: Qualitative research design. Setting: Data collection occurred in England. Method: Interviews were conducted with 15 long-term fitness bootcamp participants. Results: Thematic analysis revealed 17 facilitators and 6 barriers to long-term fitness bootcamp participation. Participants highlighted the importance of facilitators such as convenience, being outdoors and enjoyment. The social environment, including having a positive instructor and supportive group members, was further noted as a key influence on participation. While long-term participants faced occasional barriers to their routine such as physical injury, bad weather and competing events, the impact of these could be minimised through appropriate BCTs such as ‘demonstration of the behaviour’ and ‘restructuring the social/physical environment’. Conclusion: Findings from this study highlight the importance of social and environmental factors to promoting long-term fitness bootcamp participation and the inclusion of social and physical environmental restructuring as key intervention components

Circadian rhythms in microalgae production

Abstract Thesis: Circadian rhythms in microalgae production Lenneke de Winter The sun imposes a daily cycle of light and dark on nearly all organisms. The circadian clock evolved to help organisms program their activities at an appropriate time during this daily cycle. For example, UV sensitive processes, like DNA replication, can be scheduled to occur during the night (Nikaido and Johnson, 2000). In this way, the circadian clock causes rhythms in metabolic, physiological and/or behavioural events (Mittag et al., 2005). These circadian rhythms continue for some period of time following exposure to continuous light (Harding Jr et al., 1981) and have a duration of approximately 24 hours. In microalgae, circadian rhythms were observed in many processes, like nitrogen fixation, chemotaxis, photosynthesis and the cell division cycle (Mittag, 2001), which might affect the production of microalgae. Microalgae biomass can be used as source for potential biofuels, chemicals, materials, foods, feeds and high-value bioactives (Chisti, 2007; Hu et al., 2008; Wijffels and Barbosa, 2010). However, the current production process of microalgae needs to be optimized in order to become economically feasible (Norsker et al., 2011). Researchers focussed on optimizing PBR design (Molina et al., 2001; Morweiser et al., 2010; Sierra et al., 2008), operating strategies (Cuaresma et al., 2011; Morweiser et al., 2010; Olivieri et al., 2014) and microalgae metabolism (Guschina and Harwood, 2006; Klok et al., 2013a), but as of yet did not consider the possible influence of circadian rhythms on microalgae production. Biomass growth rate, biomass yield on light, and the biochemical composition of algal biomass are important factors in the production of microalgae. These factors are likely to be influenced by the day/night cycle and the circadian clock. Therefore, the aim of the work presented in this thesis was to obtain more insight in circadian rhythms in microalgae grown in photobioreactors. In chapter 2 it is described how the green microalgae Neochloris oleoabundans was grown in a photobioreactor operated as a turbidostat under continuous red LED light. Cell division in N. oleoabundans was shown to be under control of the circadian clock, and took place by multiple fission during the natural night. Due to the synchronized cell division, oscillations in biomass yield and composition were observed, despite the continuous red LED light. Synchronization disappeared under continuous white LED light, and therefore it was concluded that a blue light receptor might be involved in triggering synchronous cell division of N. oleoabundans. As biomass composition is also dependent on other culture conditions, the same set-up was used in chapter 3, only this time the culture was grown nitrogen-limited, as this is the most commonly used method for the production of storage components. In this way, it was shown that under nitrogen limitation the circadian clock was still timing cell division to the natural night. However, because of the lower growth rate, two subpopulations were observed which divided alternately every other day. Again, oscillations in biomass composition were observed. Neutral lipids were built up during the day, especially in cells that were arrested in their cell cycle. After having studied the circadian clock under continuous light conditions, a step was made to day/night cycles. Chapter 4 describes a comparison of biomass yield and composition between a synchronized culture under day/night cycles and a randomly dividing culture under continuous white LED light. In this way it was shown that circadian rhythms had a small influence on biomass yield, with biomass yield on light being 10-15% higher in synchronized cultures. Also biomass composition was influenced, as in continuous light starch never had to be spend for respiration during a dark period and therefore starch content remained higher. For the experiments with a day/night cycle, no difference was found between light supplied at constant intensity (block) or light supplied in a more natural way (sine). Therefore, providing light in a block showed to be a good and easy to operate alternative to using sinuses when working with day/night cycles in the laboratory. Chapter 5 takes a closer look at the multiple fission cell cycle of N. oleaobundans. Day/night cycles of different lengths and intensities were studied, as algae are exposed to different day lengths over the course of a year. Maximum growth rate and start of starch synthesis seemed to be regulated by the circadian clock and were scheduled after approximately 6-7 hours from sunrise. Therefore, they were not influenced by day length. However, day length did have an influence on biomass composition. In longer days, more starch was accumulated. The changes in biomass composition could also be correlated to the cell cycle of N. oleoabundans, and therefore knowledge about the timing of cell division showed to be important for the production of biomass with a desired concentration of protein, lipids, carbohydrates or pigments. In chapter 6 the implications of the overall results of this thesis for current research protocols and microalgae processes are discussed. First the occurrence of circadian rhythms in different species of microalgae is discussed, in order to establish the general nature of these rhythms. Based on the findings for N. oleoabundans, it is concluded that more research should be done using day/night cycles, as experiments under constant light are not representative for outdoor microalgae production. Still more knowledge is required on circadian rhythms in microalgae production and therefore some opportunities for future research are presented. Finally, it is discussed how manipulation of circadian rhythms might help to improve future microalgae production. </p

Alternative pediatric metabolic syndrome definitions impact prevalence estimates and socioeconomic gradients

BACKGROUND: There is no consensus regarding the definition of pediatric metabolic syndrome (MetS). This study assessed the impact of alternative definitions on the prevalence, children identified, and association with socioeconomic status (SES). METHODS: Data were from the prospective multigenerational Dutch Lifelines Cohort Study. At baseline, 9754 children participated, and 5085 (52.1%) with average follow-up of 3.0 (SD = 0.75) years were included in the longitudinal analyses; median ages were 12 (IQR = 10-14) and 14 years (IQR = 12-15), respectively. We computed MetS prevalence according to five published definitions and measured the observed proportion of positive agreement. We used logistic regression to assess the SES-MetS association, adjusted for age and sex. Longitudinal models were also adjusted for baseline MetS. RESULTS: MetS prevalence and positive agreement varied between definitions, from 0.7 to 3.0% and from 0.34 (95% CI: 0.28; 0.41) to 0.66 (95% CI: 0.58; 0.75) at baseline, respectively. We consistently found a socioeconomic gradient; in the longitudinal analyses, each additional year of parental education reduced the odds of having MetS by 8% (95% CI: 1%; 14%) to 19% (95% CI: 7%; 30%). CONCLUSIONS: Alternative MetS definitions had differing prevalence estimates and agreed on 50% of the average number of cases. Additionally, regardless of the definition, low SES was a risk factor for MetS. IMPACT: Little is known about the impact of using different definitions of pediatric metabolic syndrome on study results. Our study showed that the choice of pediatric metabolic syndrome definition produces very different prevalence estimates. We also showed that the choice of definition influences the socioeconomic gradient. However, low socioeconomic status was consistently a risk factor for having pediatric metabolic syndrome. In conclusion, studies using different definitions of metabolic syndrome could be reasonably compared when investigating the association with socioeconomic status but not always validly when comparing prevalence studies

Pediatric metabolic syndrome definitions impact prevalence and socioeconomic gradients

The choice of pediatric metabolic syndrome (MetS) definition influences prevalence estimates, but further implications, especially on the association with socioeconomic status (SES), are not well-known. This hampers a synthesis of the evidence to help guide the relevant stakeholders. For this reason, we aim to assess the impact of alternative definitions on the prevalence of MetS, the children that are identified, and the association between SES and MetS.Data were used from the Lifelines Cohort Study, a prospective multigenerational cohort in the Netherlands. At baseline 9,754 children participated, of which 5,085 (52.1\ were included in the longitudinal analyses. We computed the prevalence of MetS according to five published definitions and measured the observed positive agreement between pairs of definitions, indicating the proportion of agreement across the average number of MetS cases. Logistic regression was used to assess the association between SES and MetS. All models were adjusted for age and sex; the longitudinal models were also adjusted for baseline MetS status.The prevalence rates of MetS varied between definitions (0.7-3.0\, but positive agreement between MetS definitions was generally fair to good ranging from 0.34 (95\CI) 0.28; 0.41) to 0.66 (95\.58; 0.75) at baseline. At both assessments, we found an inverse association between baseline SES and MetS, which ranged from 0.81 (95\.70; 0.93) to 0.92 (95\.86; 0.98) per definition in the longitudinal analyses with a mean follow-up (SD) of 3.0 (0.75) years.Alternative definitions of MetS lead to differing prevalence estimates, and they agreed on 50\ regardless of which definition was used we concluded low SES was a risk factor for developing MetS.Evidence regarding different definitions of metabolic syndrome in children can be combined because the agreement among definitions is generally fair to good.As low socioeconomic status is a consistent risk factor for developing metabolic syndrome, preventive interventions should preferentially target children from low socioeconomic backgrounds

Socioeconomic Health Inequalities in Adolescent Metabolic Syndrome and Depression:No Mediation by Parental Depression and Parenting Style

We assessed to what extent parental depression and parenting style mediate the relationships between different measures of parental socioeconomic status (SES) and both depression and metabolic syndrome (MetS) in adolescents, and whether sex moderates these mechanisms. Data were from the prospective multigenerational Dutch Lifelines Cohort Study. Our sample consisted of 1217 adolescents with an average follow-up of 33.3 (SD = 7.33) months and a median baseline age of 13 (IQR:13–14) years. We used structural equation models to assess the direct and indirect effects of SES on baseline and changes at follow-up in both depression and MetS, and to assess moderation by sex. For each additional year of education, continuous MetS scores were 0.098 (95%CI: 0.020; 0.184) units lower at baseline and decreased 0.079 (95%CI: 0.004; 0.158) units at follow-up. No other direct or indirect effects of SES were found, and there was no moderation by sex. Additionally, warmer parenting style was generally associated with more favorable outcome scores. Therefore, improving parenting style may improve health for all adolescents. However, in this study parental depression and parenting style did not account for adolescent socioeconomic health inequalities. This may be partly due to good access to social services within the Netherlands