Photovoltaic cell electrical heating system for removing snow on panel including verification

Abstract

Small photovoltaic plants in private ownership are typically rated at 5 kW (peak). The panels are mounted on roofs at a decline angle of 20° to 45°. In winter time, a dense layer of snow at a width of e.g., 10 cm keeps off solar radiation from the photovoltaic cells for weeks under continental climate conditions. Practically, no energy is produced over the time of snow coverage. Only until outside air temperature has risen high enough for a rather long-time interval to allow partial melting of snow; the snow layer rushes down in an avalanche. Following this proposal, snow removal can be arranged electrically at an extremely positive energy balance in a fast way. A photovoltaic cell is a large junction area diode inside with a threshold voltage of about 0.6 to 0.7 V (depending on temperature). This forward voltage drop created by an externally driven current through the modules can be efficiently used to provide well-distributed heat dissipation at the cell and further on at the glass surface of the whole panel. The adhesion of snow on glass is widely reduced through this heating in case a thin water film can be produced by this external short time heating. Laboratory experiments provided a temperature increase through rated panel current of more than 10 °C within about 10 min. This heating can initiate the avalanche for snow removal on intention as described before provided the clamping effect on snow at the edge of the panel frame is overcome by an additional heating foil. Basics of internal cell heat production, heating thermal effects in time course, thermographic measurements on temperature distribution, power circuit opportunities including battery storage elements and snow-removal under practical conditions are described.

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Antioxidant enzyme activities of Folsomia candida and avoidance of soil metal contamination

Abstract

Induction of the antioxidant enzymes catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) and the avoidance of potentially toxic metals in soil by Folsomia candida were investigated. Both laboratory-spiked and field-polluted agricultural soils were used. Cadmium (Cd) concentrations in body tissues, animal avoidance behaviour and physico-chemical properties of the field soils were also determined. In laboratory Cd-spiked soils, the CAT and SOD activities in the Cd treatments were 71.1–94.7 and 1.31–4.55 times higher than in the control, respectively. In field-polluted agricultural soils, the CAT and POD activities generally increased with increasing pollution index (PI _Nemerow ) of soil Cd, Cu, Pb and Zn. The CAT, POD and SOD activities at different PI _Nemerow were 65.7–128, 30.1–180 and 36.5–95.8% higher than in the control, respectively. In line with the enzyme activities, Cd concentrations in the animal bodies were 8.31–15.1 and 3.21–10.0 times higher than in the control in spiked and field-polluted soils, respectively. Avoidance behaviour also increased with increasing metal concentrations in both soils. The effects of metals on CAT, POD or SOD activity were influenced by soil properties such as soil texture and pH. These results indicate that the antioxidant enzymes activities of F. candida can be induced by heavy metals and potentially used to assess the toxicity, and also that soil properties must be considered in the analysis of enzyme activities in different types of field soils.

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Patterns of allergic sensitization and atopic dermatitis from 1 to 3 years: effects on allergic diseases

Abstract

Background

While allergic sensitization and atopic dermatitis (AD) are known to increase the risk for allergic diseases, the impact of different temporal and clinical patterns of sensitization and AD is less well defined.

Objective

We investigated patterns of sensitization and AD from early infancy to age 3, and the differential risk for developing allergic diseases within each pattern in a general cohort.

Methods

Children (n=2629) from the Canadian Healthy Infant Longitudinal Development (CHILD) Study underwent skin prick tests and were assessed clinically for AD at ages 1 and 3 years. We applied an unsupervised latent class analysis (LCA) to the following 5 factors at these ages: AD, food sensitization, inhalant sensitization, poly-sensitization to foods, and poly-sensitization to inhalants. The risks for developing asthma, allergic rhinitis and food allergy at 3 years were evaluated for each identified group.

Results

Five distinct classes were revealed by LCA: healthy (81.8%), atopic dermatitis (7.6%), inhalant sensitization (3.5%), transient sensitization (4.1%), and persistent sensitization (3.2%). Using healthy children as the baseline, children in the "atopic dermatitis" group had the next lowest risk for all allergic outcomes at 3 years; those in the "inhalant sensitization" group had the highest risk for allergic rhinitis; children in the "transient sensitization" group were at an increased risk for food allergy; while children in the "persistent sensitization" group had the highest risk for all allergic diseases.

Conclusion and Clinical Relevance

There is substantial heterogeneity among allergen-sensitized children. Researchers and clinicians need to be aware of the non-specificity associated with labelling children simply as "atopic" and "non-atopic" without considering the timing of their atopic history, type of sensitization, and AD status. Children with AD who were poly-sensitized to foods at an early age appear to be at greatest risk of developing other allergic diseases.

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Asthma and Lung Function in Adulthood after a Viral Wheezing Episode in Early Childhood

Abstract

Background

Viral etiology of infection has a significant role in the long-term outcome of early-childhood wheezing.

Objective

This study examines asthma and lung function in adulthood after early-childhood wheezing induced by respiratory syncytial virus (RSV) and rhinovirus (RV).

Methods

A total of 100 children were hospitalized for a wheezing episode at less than 24 months of age from 1992 to 1993 in Kuopio University Hospital (Finland). Adenovirus, influenza A and B virus, parainfluenza (1-3) virus, and RSV were tested on admission using antigen detection and antibody assays, and RSV and RV were tested by polymerase chain reaction (PCR). In 2010, 49 cases and 60 population controls attended a follow-up study, which included spirometry with bronchodilation test and fractionally exhaled nitric oxide (FE_NO) measurements.

Results

Current asthma was present in 64% of the cases with RV-induced wheezing [OR 17.0 (95%CI 3.9-75.3) vs. controls], in 43% of the cases with RSV-induced wheezing episode [6.1 (1.5-24.9) vs. controls], and in 12% of the controls. The RV group showed significantly higher mean FE_NO values than the RSV group and controls. RV-positive cases had lower MEF50 before bronchodilation and higher MEF50, FEV1, and FEV1/FVC bronchodilation responses than controls. RSV-positive cases had lower FVC than controls before bronchodilation.

Conclusion

Cases with RV- and RSV-induced early-childhood wheezing had increased risk for asthma in adulthood, and RV-positive cases had significantly higher FE_NO values than RSV-positive cases and controls. Compared to controls RV-positive cases showed more bronchial reactivity, and RSV-positive cases showed lower FVC before bronchodilation in lung function testing.

Clinical relevance

Children with RV- or RSV-induced wheezing in early childhood have an increased risk for asthma and lung function abnormalities in adulthood.

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Short-term changes in chewing efficiency and subjective evaluation in normal dentate subjects after insertion of oral appliances with an occlusal flat table

Summary

Background

Oral appliances with an occlusal flat table are used as treatment dentures. However, the short-term effect of insertion of such oral appliances on chewing has not been reported.

Objective

This study aimed to determine whether experimental and continuous insertion of oral appliances with an occlusal flat table has an effect on chewing efficiency and Oral Health Impact Profile (OHIP) in healthy participants.

Methods

Ten participants each in the oral-appliance and control (no oral-appliance insertion) groups attended six data collection sessions for 5 consecutive days. Participants answered the OHIP questionnaire and underwent the chewing efficiency test. For each parameter, intergroup differences were investigated in terms of change from baseline to immediately after oral-appliance insertion (0 h; p < 0.05) and from 0 h to 24, 48, 72, and 96 h after oral-appliance insertion (p < 0.05).

Results

There were significant differences between groups in the degree of change in chewing efficiency and OHIP scores for functional limitation, physical pain, physical disability, and handicap from baseline to 0 h (all, p < 0.001); among these, only OHIP scores for functional limitation and physical pain demonstrated significant differences in degree of change between the two groups at 96 h after appliance insertion (p = 0.477 and 0.275, respectively). Differences between the two groups in the degree of change in other parameters were not significant.

Conclusion

Insertion of oral appliances caused a decrease in chewing efficiency and an increase in OHIP scores. Continuous insertion improved functional limitation and physical pain within 96 h.

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Case 35-2017: A 57-Year-Old Woman with Hypoesthesia and Weakness in the Legs and Arms

Presentation of Case. Dr. Daniel B. Rubin (Neurology): A 57-year-old-woman was admitted to this hospital because of progressive hypoesthesia, paresthesia, and weakness in the arms and legs. The patient had been in her usual health until 18 months before this admission, when paresthesia developed in…

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Coronary risk assessment at X-ray dose equivalent ungated chest CT: Results of a multi-reader study

Publication date: May–June 2018
Source:Clinical Imaging, Volume 49
Author(s): Michael Messerli, Lukas Hechelhammer, Sebastian Leschka, René Warschkow, Simon Wildermuth, Ralf W. Bauer
ObjectivesTo determine the value of ultra-low dose chest CT with tin filtration for ordinal coronary artery calcium (CAC) risk scoring.Methods50 patients were prospectively included and underwent clinical standard dose chest CT (1.8±0.7mSv) and ultra-low dose CT (0.13±0.01mSv). Four radiologists estimated presence and extent of CAC.ResultsWeighted kappa values for CAC were 0.76–0.97 in standard dose and 0.75–0.95 in ultra-low dose CT (p<0.001). Good to excellent agreement was observed for CAC ordinal risk assessment, with readers reporting identical risk in 81% of cases.ConclusionCAC risk can be qualitatively assessed from X-ray dose equivalent ungated chest CT.



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