Online short-term solar power forecasting

This paper describes a new approach to online forecasting of power production from PV systems. The method is suited to online forecasting in many applications and in this paper it is used to predict hourly values of solar power for horizons of up to 36 h. The data used is 15-min observations of solar power from 21 PV systems located on rooftops in a small village in Denmark. The suggested method is a two-stage method where first a statistical normalization of the solar power is obtained using a clear sky model. The clear sky model is found using statistical smoothing techniques. Then forecasts of the normalized solar power are calculated using adaptive linear time series models. Both autoregressive (AR) and AR with exogenous input (ARX) models are evaluated, where the latter takes numerical weather predictions (NWPs) as input. The results indicate that for forecasts up to 2 h ahead the most important input is the available observations of solar power, while for longer horizons NWPs are the most important input. A root mean square error improvement of around 35% is achieved by the ARX model compared to a proposed reference model.     

Survey of air pollution in Cotonou, Benin--air monitoring and biomarkers

Exposure to genotoxic compounds present in ambient air has been studied in Cotonou, Benin, a city where two-stroke motorbikes are the major form of transportation and gasoline quality is poor. Personal monitoring and biomarkers were used to assess the exposure. Non-smoking taxi-moto drivers (city) and village residents were the study subjects. Benzene exposure was significantly higher in the city, as compared to the village (76.0+/-26.8 microg/m(3) versus 3.4+/-3.0, p=0.0004). Urinary excretion of benzene and S-phenylmercapturic acid (S-PMA) were also highest in subjects living in the city, whereas 1-hydroxypyrene was not different. The level of total polycyclic aromatic hydrocarbons (PAHs), associated with particles, ranged from 76.21 to 103.23 in Cotonou versus 1.55 ng/m(3) for the village. Determination of DNA damage in lymphocytes showed that subjects from the city had elevated number of lesions compared to subjects in the village in terms of bulky DNA adducts, 8-hydroxy-2'-deoxyguanosine and 5-methylcytosine, whereas DNA fragmentations analysed by alkaline gel electrophoresis was not different between the subjects. In conclusion, this study shows that air pollution is pronounced in Cotonou, Bénin and is associated with elevated levels of DNA damage in residents of the city compared to people living in a non-polluted rural village.     

Performance Study of a Closed-Type Heat Pump Tumble Dryer Using a Simulation Model and an Experimental Set-Up

In the interests of competitiveness, manufactures of tumble dryers are seeking to reduce both their electricity use and the drying time. This study examines how the cylinder volume of the compressor and the total heat transfer of the condenser influence the drying time and electricity use in a heat pump tumble dryer. A transient simulation model was developed and compared to an experimental set-up with good similarity. The simulations show that increasing the cylinder volume of the compressor by 50% decreases the drying time by 14% without using more electricity.     

Evaluation of Two Different Questionnaires used for Diagnosing Ocular Manifestations in the Sick Building Syndrome on the Basis of an Objective Index

The paper evaluates ocular manifestations as reported in two different questionnaires completed within one to Two weeks by 164 office workers in four town halls in Copenhagen. Among 14 previously investigated, these town halls constitute the two with the highest and the two with the lowest prevalence of the Sick Building Syndrome (defined as mucous membrane complaints such as eye, nose or throat irritation, and general symptoms such as headaches or fatigue several times a week). There was a highly significant rank correlation in each of the four town halls between the frequency of self-reported ocular manifestations in the two questionnaires. Furthermore, the eye complaints reported in both questionnaires were significantly correlated with an objective measure for eye dryness, investigated using a biomicroscope. By combining the two questionnaires it was possible to define subgroups using both frequency of eye complaints and consistency of reporting in the two questionnaires. The subgroup of 107 subjects with consistency in the frequency of their eye complaints in the two questionnaires showed a significantly higher correlation with the objective index than did the subjects with inconsistent reporting. Furthermore, with increased frequency of complaints and consistency of reporting, not only the prevalence of microscopically determined eye dryness, but also the number of up to 7 different eye symptoms per subject increased, and an increased percentage of these symptoms was found to be related to sensory reactions in the common chemical sense, which earlier has been postulated to be involved in the Sick Building Syndrome. In conclusion, the study shows that data from two different questionnaires on self-reported ocular manifestations associated with the Sick Building Syndrome are reproducible and associated with objective dryness in the eyes.     

A method for production and determination of histamine releasing activity from human peripheral blood mononuclear cells

Cell-cell adhesion mediated by E-cadherin is often lost or disturbed in human carcinomas. For regular adhesive function, E-cadherin has to form complexes with peripheral cytoplasmic catenins which are multifunctional proteins that are also involved in signal transduction and growth regulation. We have analyzed the expression levels of the genes encoding alpha-catenin, beta-catenin and plakoglobin in correlation to the E-cadherin expression levels in cell lines derived from human cervical carcinomas. Reduced mRNA and protein levels were detected for plakoglobin, whereas alpha- and beta-catenin showed only reduced protein (but not mRNA) levels. The alterations in catenin gene expression were often associated with absent or reduced E-cadherin. The findings indicate that a reduction of catenin gene expression may contribute to the development of cervical carcinomas.     

Bias in spatial location due to categorization: Comment on Tversky and Schiano.

B. Tversky and D. J. Schiano (1989) reported bias in reproducing the angle of a line in an "ell" frame. When no conceptual interpretation of the task was given, they argued that the bias was due to a perceptual process that produced an apparent tilt in the line (D. J. Schiano & B. Tversky, 1992). We propose that J. Huttenlocher, L. V. Hedges, and S. Duncan's (1991) model of category effects on estimates of stimulus values provides a better explanation of this bias. Two experiments are presented that examine these alternative views. The results show effects of the orientation of the frame and of an interference task on bias that are more consistent with J. Huttenlocher et al.'s model than with the perceptual explanation adopted by D. J. Schiano and B. Tversky. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

In utero exposure to extra vitamin D from food fortification and the risk of subsequent development of gestational diabetes: the D-tect study

Background

The primary aim of this study was to assess whether exposure during fetal life to extra vitamin D from food fortification was associated with a reduction in the risk of subsequently developing gestational diabetes mellitus (GDM). Furthermore, we examined whether the effect of the vitamin D from fortification differed by women’s season of birth.

Methods

This semi-ecological study is based on the cancellation in 1985 of the mandatory policy to fortify margarine with vitamin D in Denmark, with inclusion of entire national adjacent birth cohorts either exposed or unexposed to extra vitamin D in utero. The identification of GDM cases later in life among both exposure groups was based on the Danish national health registers. Logistic regression analyses generating odds ratios (ORs) and 95% confidence intervals (95% CIs) were performed.

Results

Women who were prenatally exposed to the extra vitamin D from fortification tended to have a lower risk of subsequently developing GDM than unexposed women (OR 0.87, 95%CI 0.74,1.02, P?=?0.08). When analyses were stratified by women’s season of birth, exposed women born in spring had a lower risk of developing GDM compared to unexposed subjects (OR 0.68, 95%CI 0.50,0.94, p?=?0.02).

Conclusion

This study suggests that prenatal exposure to extra vitamin D from mandatory fortification may lower the risk of developing gestational diabetes among spring-born women.

Trial registration

This study is part of the D-tect project, which is registered on clinicaltrials.gov: NCT03330301.