Split-Stirling-cycle displacer linear-electric drive

The retrofit of a 1/4-W split-Stirling cooler with a linear driven on the displacer was achieved and its performance characterized. The objective of this work was to demonstrate that a small linear motor could be designed to meet the existing envelope specifications of the cooler and that an electric linear drive on the displacer could improve the cooler's reliability and performance. The paper describes the characteristics of this motor and presents cooler test results

The Phenion (R) Full-Thickness Skin Model for Percutaneous Absorption Testing

In recent years many efforts have been made to replace dermal toxicity testing of chemicals in the animal by in vitro assays. As a member of a German research consortium, we have previously contributed to the validation of an in vitro test protocol for percutaneous absorption studies on the basis of reconstructed human epidermis and both human and pig skin ex vivo. Aiming to assess the barrier properties of a newly developed reconstructed skin model, this protocol has now been transferred to the Phenion (R) Full-Thickness Skin Model (FT model). The permeation of testosterone and caffeine was quantified in parallel to that of pig skin using Franz-type diffusion cells. In addition, the permeation of benzoic acid and nicotine was studied. As expected, the FT model is more permeable than pig skin, yet its barrier properties are well in accordance with those of reconstructed human epidermis when compared to previous data. In fact, the FT model most efficiently retards testosterone as the compound of highest lipophilicity, which can be explained by an additional uptake by a reservoir formed by the dermis equivalent. Thus, the structure closely parallels human skin. In consequence, the Phenion FT model appears to be suitable for percutaneous absorption studies in hazard analysis and should be subjected to a catch-up validation study. Copyright (C) 2009 S. Karger AG, Base

Collectins and cationic antimicrobial peptides of the respiratory epithelia

The respiratory epithelium is a primary site for the deposition of microorganisms that are acquired during inspiration. The innate immune system of the respiratory tract eliminates many of these potentially harmful agents preventing their colonization. Collectins and cationic antimicrobial peptides are antimicrobial components of the pulmonary innate immune system produced by respiratory epithelia, which have integral roles in host defense and inflammation in the lung. Synthesis and secretion of these molecules are regulated by the developmental stage, hormones, as well as many growth and immunoregulatory factors. The purpose of this review is to discuss antimicrobial innate immune elements within the respiratory tract of healthy and pneumonic lung with emphasis on hydrophilic surfactant proteins and β-defensins

Thirteen years follow-up after radical transsternal thymectomy for myasthenia gravis. Do short-term results predict long-term outcome?

Objective: Long-term evaluation of efficacy and quality of life after radical surgical approach for myasthenia gravis (MG). Comparison between short-term follow-up and long-term outcome. Methods: All patients (n=26, 16 men and 10 women, mean age: 40.7 years) underwent total transsternal thymectomy for MG between 1986 and 1989. Prospective analysis of the patients for short-term follow-up (mean 22.4 months) was published in 1991. The same group of patients was reevaluated in 2001 (range of follow-up 11.4-15.2 years) and assessed according to the classification of Osserman and Oosterhuis. Results: Mean follow-up was 13.0 years (range 11.4-15.2 years). Two patients were lost from follow-up and one died 4 years after thymectomy for reasons unrelated to MG (n=23). No early or late postoperative mortality was observed. One sternal osteomyelitis occurred. Late postoperative morbidity included sternal instabilities (n=2), mild residual thoracic pain (n=6), and hypertrophic scars (n=7). Five patients were rehospitalized for aggravating MG and needed plasmapheresis (n=3) and intubation (n=1). Thirteen patients (56.5%) showed objective clinical improvement, including six patients (26.1%) with complete remission. Eleven patients (47.8%) do not take any medication at all. Because some late relapse may occur several years after operation, the rate of improvement decreased slightly, whereas the difference between short and long-term follow-up was not statistically significant (P=0.405). Twenty patients (87%) returned to work, including part-time occupation (n=4). Fourteen patients (61%) are performing sports regularly. Conclusions: Our data confirm that radical, transsternal thymectomy is an effective and safe therapeutic modality for MG. Short-term results seem to deteriorate over time, therefore long-term studies for minimally invasive approaches have to prove equal results before replacing the standard procedur

Coming to Your Senses: Promoting Critical Thinking about Sensors through Playful Interaction in Classrooms

Learning through exploration is assumed to be a powerful way of introducing children to computer science concepts. However, it is uncertain how exploring physical computing toolkits can promote movement between conceptual knowledge and abstract reflection, and lead to critical thinking about technology. We investigated how children aged 9-11 years explored and reasoned about personal and environmental data sensors, using a playful exploration-based physical toolkit in their classroom. We report on the ways in which critical thinking about sensor accuracy and reliability developed through reflective dialogue and playful interaction, taking into account the support structures embedded in the classroom. Finally, we discuss strategies for designing exploration-based learning for classroom settings, to promote critical thinking about data sensing

TeV neutrinos and gamma rays from pulsars

Recent studies suggest that pulsars could be strong sources of TeV muon neutrinos provided positive ions are accelerated by pulsar polar caps to PeV energies. In such a situation muon neutrinos are produced through the delta resonance in interactions of pulsar accelerated ions with its thermal radiation field. High energy gamma rays also should be produced simultaneously in pulsar environment as both charged and neutral pions are generated in the interactions of energetic hadrons with the ambient photon fields. Here we estimate TeV gamma ray flux at Earth from few nearby young pulsars. When compared with the observations we find that proper consideration of the effect of polar cap geometry in flux calculation is important. Incorporating such an effect we obtain the (revised) event rates at Earth due to few potential nearby pulsars. The results suggest that pulsars are unlikely to be detected by the upcoming neutrino telescopes. We also estimate TeV gamma ray and neutrino fluxes from pulsar nebulae for the adopted model of particle acceleration.Comment: Six pages, accepted in MNRA

Effect of oral calcium loading on intact PTH and calcitriol in idiopathic renal calcium stone formers and healthy controls

The calciuric response after an oral calcium load (l000 mg elemental calcium together with a standard breakfast) was studied in 13 healthy male controls and 21 recurrent idiopathic renal calcium stone formers, 12 with hypercalciuria (UCa×V>7.50 mmol/24 h) and nine with normocalciuria. In controls, serum 1,25(OH)2 vitamin D3 (calcitriol) remained unchanged 6 h after oral calcium load (50.6±5.1 versus 50.9±5.0 pg/ml), whereas it tended to increase in hypercalciuric (from 53.6±3.2 to 60.6±5.4 pg/ml, P=0.182) and fell in normocalciuric stone formers (from 45.9±2.6 to 38.1±3.3 pg/ml, P=0.011). The total amount of urinary calcium excreted after OCL was 2.50±0.20 mmol in controls, 2.27±0.27 mmol in normocalciuric and 3.62±0.32 mmol in hypercalciuric stone formers (P=0.005 versus controls and normocalciuric stone formers respectively); it positively correlated with serum calcitriol 6 h after calcium load (r=0.392, P=0.024). Maximum increase in urinary calcium excretion rate, δCa-Emax, was inversely related to intact PTH levels in the first 4 h after calcium load, i.e. more pronounced PTH suppression predicted a steeper increase in urinary calcium excretion rate. Twenty-four-hour urine calcium excretion rate was inversely related to the ratio of δ calcitriol/δPTHmax after calcium load (r=−0.653, P=0.0001), indicating that an abnormally up-regulated synthesis of calcitriol and consecutive relative PTH suppression induce hypercalciuria. Finally, late absorption of calcium as suggested by maximum urinary calcium excretion beyond 4 h after oral calcium load was as rare in hypercalciuric stone formers (2 of 12) as in controls (1 of 13) and did not occur in normocalciuric stone former