Cigarette smoking and submaximal exercise test duration in a biracial population of young adults: the CARDIA study

Symptom-limited, graded exercise treadmill testing was performed by 4,968 white and black adults, ages 18-30 yr, during the baseline examination for the Coronary Artery Risk Development in Young Adults (CARDIA) study. Compared with nonsmokers, the mean exercise test duration of smokers was 29-64 s shorter depending on race/gender group (all P < 0.001), but mean duration to heart rate 130 (beats.min-1) ranged from 20-50 s longer (P < 0.05). In each race/gender group, test duration to heart rates up to 150 was 15-35 s longer (P < 0.05) in smokers than in nonsmokers after adjustment for age, sum of skinfolds, hemoglobin, and physical activity score. The mean maximum heart rate was lower in smokers than in nonsmokers (difference ranging from 6.7 beats.min-1 in white men to 11.2 beats.min-1 lower in black women, P < 0.001), although maximum rating of perceived exertion was nearly identical in smokers and nonsmokers. Chronic smoking appears to blunt the heart rate response to exercise, so that exercise duration to submaximal heart rates is increased even though maximal performance is impaired. This may result from downloading of beta-receptors caused by smoking. Smoking status should be considered in the evaluation of physical fitness data utilizing submaximal test protocols, or else the fitness of smokers relative to nonsmokers is likely to be overestimated.     

Survey of 1012 moldy dwellings by culture fungal analysis: Threshold proposal for asthmatic patient management

Different countries have tried to define guidelines to quantify what levels of fungi are considered as inappropriate for housing. This retrospective study analyzes indoor fungi by cultures of airborne samples from 1012 dwellings. Altogether, 908 patients suffering from rhinitis, conjunctivitis, and asthma were compared to 104 controls free of allergies. Portuguese decree law no 118/2013 (PDL118), ANSES (a French environmental and health agency) recommendations, and health regulations of Besançon University Hospital were applied to determine the rates of non‐conforming dwellings, which were respectively 55.2%, 5.2%, and 19%. Environmental microbiological results and medical data were compared. The whole number of colonies per cubic meter of air was correlated with asthma (P < 0.001) and rhinitis (P = 0.002). Sixty‐seven genera and species were detected in bedrooms. Asthma was correlated to Aspergillus versicolor (P = 0.004) and Cladosporium spp. (P = 0.02). Thresholds of 300 cfu/m³ for A. versicolor or 495 cfu/m³ for Cladosporium spp. are able to discriminate 90% of the asthmatic dwellings. We propose a new protocol to obtain an optimal cost for indoor fungi surveys, excluding surface analyses, and a new guideline to interpret the results based on >1000 cfu/m³ of whole colonies and/or above threshold levels for A. versicolor or Cladosporium spp.     

Near-threshold fatigue propagation of physically through-thickness short and long cracks in a low alloy steel

In this paper, the near-threshold fatigue behavior of physically through-thickness short cracks and of long cracks in a low alloy steel is investigated by experiments in ambient air. Physically through-thickness short fatigue cracks are created by gradually removing the plastic wake of long cracks in compact tension specimens. The crack closure is systematically measured using the compliance variation technique with numerical data acquisition and filtering for accurate detection of the stress intensity factor (SIF) at the crack opening. Based on the experimental results, the nominal threshold SIF range is shown to be dependent on the crack length and the characteristic of the crack wake which is strongly dependent on the loading history. The effective threshold SIF range and the relation between the crack propagation rate and the effective SIF range after the crack closure correction are shown to be independent on crack length and loading history. The shielding effect of the crack closure is shown to be related to the wake length and load history. The effective threshold SIF range and the relationship between the crack growth rate and the effective SIF range appear to be unique for this material in ambient air. These properties can be considered as specific fatigue properties of the couple material/ambient air environment.     

The Hybrid Finite Element Mixing Cell Method: A New Flexible Method for Modelling Mine Ground Water Problems

Dewatering operations often stop at mine closure. The ground water rebound can have undesirable consequences, which numerical models can help one understand and manage. However, classical modelling techniques are relatively unsuitable to these contexts. While spatially distributed and physically based models suffer difficulties due to the lack of data and the complexity of geological and hydrogeological conditions, black-box models are too simple to deal with the problems effectively. A new modelling method is proposed to simulate ground water environments in which water flows through mined (exploited) and unmined (unexploited) areas. Exploited zones are simulated using a group of mixing cells possibly interconnected by pipes. Unexploited zones are simultaneously simulated using classical finite elements. This combined approach allows explicit calculation of ground water flows around the mine and mean water levels in the exploited zones. Water exchanges between exploited zones and unexploited zones are simulated in the model using specifically defined internal boundary conditions. The method is tested on synthetic cases of increasing complexity, and first results from a real case study are presented.     

Electroluminescence from porous silicon in the cathodic reduction of persulfate ions: Degree of reversibility of the tuning effect

The temporal evolution of the spectra of cathodic electroluminescence from porous silicon in an electrolyte containing persulfate ions S₂O ₈ ^2? was studied in the galvanostatic mode. It was shown that irreversible changes in luminescence properties of porous silicon occur under cathodic polarization. These changes are manifested in a decrease in the signal intensity and a long-wavelength shift of the electroluminescence (EL) spectrum when the substrate potential remains virtually unchanged (pseudo-tuning). The irreversibility of the change in luminescence parameters is related to a concurrent electrochemical oxidation of the surface of porous silicon, which hinders the bipolar injection of carriers into luminescence-active crystallites. The results obtained suggest that the degradation phenomena observed under cathodic polarization are due to those same processes which are responsible for EL excitation, which casts doubt on the interpretation of the tuning effect, known in the literature, as a consequence of a purely electronic process in porous silicon.     

A Novel Experimental Approach to PLE Spectral Measurement in PS: Results and Simulation

The detailed study of photoluminescence excitation (PLE) spectra in thick porous silicon (PS) layers is carried out using modified experimental technique. Instead of monochromatic detection usually used, a PLE signal is recorded over the whole emission band from a PS layer. For the first time, this technique allowed us to obtain the reliable PLE data up to far UV range of excitation energy E_exc = 5.4 eV. The PLE spectra showed increasing region below the maximum at E_exc 4.3 eV, then PLE intensity decreased monotonically. The absorption spectrum for PS layers is extracted from the same PLE data using depth profiling method. Low-energy region of the PLE spectra is satisfactorily simulated in terms of quantum confinement model assuming a constant quantum efficiency and log-normal size distribution of silicon nanocrystallites. The PLE decrease above E_exc 4.3 eV is discussed assuming that hot electrons may be injected from silicon crystallites to adjacent oxide phase in PS. In this way, leaving electrons give rise to nonradiative losses.