The association of families' socioeconomic and demographic characteristics with parents' perceived barriers to returning to youth sport following the COVID-19 pandemic.

Developmentally appropriate sport contexts have the potential to positively influence young people's physiological, psychological, and social outcomes. However, little is known about how families returned to sport in the wake of COVID-19-related restrictions or how socioeconomic and demographic factors influenced parents' perceptions of barriers to returning. A nationally representative sample (N = 6183) of American youth sport parents completed a questionnaire in which they provided demographic information and answered questions related to the barriers they perceived in returning to sport, such as the risk of their child getting sick. Structural equation modeling was used to examine the relationships among a range of socioeconomic and demographic factors and these barriers to returning. Results suggest that parents from racially minoritized and urban neighborhoods held higher levels of concern over health-related and practical barriers to returning to sport. Findings highlight the importance of designing available, equitable, and appropriate youth sport contexts.

Lessons learnt from evaluating full-scale ammonium feedback control in three large wastewater treatment plants.

Three large wastewater treatment plants in Sweden participate in a project evaluating different types of ammonium feedback controllers in full-scale operation. The goal is to improve process monitoring, maintain effluent water quality and save energy. The paper presents the outcome of the long-term evaluation of controllers. Based on the experiences gained from the full-scale implementations, a discussion is provided about energy assessment for the purpose of comparing control strategies. The most important conclusions are the importance of long-term experiments and the difficulty of comparing energy consumption based on air flow rate measurements.

Instrumentation, control and automation in wastewater--from London 1973 to Narbonne 2013.

Key developments of instrumentation, control and automation (ICA) applications in wastewater systems during the past 40 years are highlighted in this paper. From the first ICA conference in 1973 through to today there has been a tremendous increase in the understanding of the processes, instrumentation, computer systems and control theory. However, many developments have not been addressed here, such as sewer control, drinking water treatment and water distribution control. It is hoped that this review can stimulate new attempts to more effectively apply control and automation in water systems in the coming years.

The optimal dissolved oxygen profile in a nitrifying activated sludge process - comparisons with ammonium feedback control.

Ammonium feedback control is increasingly used to determine the dissolved oxygen (DO) set-point in aerated activated sludge processes for nitrogen removal. This study compares proportional-integral (PI) ammonium feedback control with a DO profile created from a mathematical minimisation of the daily air flow rate. All simulated scenarios are set to reach the same treatment level of ammonium, based on a daily average concentration. The influent includes daily variations only and the model has three aerated zones. Comparisons are made at different plant loads and DO concentrations, and the placement of the ammonium sensor is investigated. The results show that ammonium PI control can achieve the best performance if the DO set-point is limited at a maximum value and with little integral action in the controller. Compared with constant DO control the best-performing ammonium controller can achieve 1-3.5% savings in the air flow rate, while the optimal solution can achieve a 3-7% saving. Energy savings are larger when operating at higher DO concentrations.

Aeration control - a review.

This review covers automatic control of continuous aeration systems in municipal wastewater treatment plants. The review focuses on published research in the 21st century and describes research into various methods to decide and control the dissolved oxygen (DO) concentration and to control the aerobic volume with special focus on plants with nitrogen removal. Important aspects of control system implementation and success are discussed, together with a critical review of published research on the topic. With respect to DO control and determination, the strategies used for control span from modifications and developments of conventional control methods which have been explored since the 1970s, to advanced control such as model-based predictive and optimal controllers. The review is supplemented with a summary of comparisons between control strategies evaluated in full-scale, pilot-scale and in simulations.

We know what we know, but from whom did we learn it? A sociodemographic history of participant characteristics and reporting practices in sport and exercise psychology.

The majority of research participants in the social sciences are recruited from populations that are Western, educated, industrialized, rich, and democratic. This has the potential to threaten the external validity and limit the generalizability of research findings. It also highlights the need to provide a historical accounting of participant characteristics and reporting practices across coherent disciplines of research. This paper reports the participant characteristics from studies published in 12 leading journals in the sport and exercise psychology literature. In total, 15,650 peer-reviewed articles were published across these outlets from 1930 to 2021, involving 4,487,437 human participants. A descriptive overview of participant characteristics and reporting practices suggests that empirical understanding of human experiences and outcomes in sport and exercise settings is built from an incomplete and unrepresentative sample of participants. Findings illuminate potential knowledge gaps that may have resulted from the lack of diverse samples and offer potential paths forward for contemporary sport and exercise psychology scholars who wish to address these gaps.

Exploring gravity with the MIGA large scale atom interferometer.

We present the MIGA experiment, an underground long baseline atom interferometer to study gravity at large scale. The hybrid atom-laser antenna will use several atom interferometers simultaneously interrogated by the resonant mode of an optical cavity. The instrument will be a demonstrator for gravitational wave detection in a frequency band (100 mHz-1 Hz) not explored by classical ground and space-based observatories, and interesting for potential astrophysical sources. In the initial instrument configuration, standard atom interferometry techniques will be adopted, which will bring to a peak strain sensitivity of [Formula: see text] at 2 Hz. This demonstrator will enable to study the techniques to push further the sensitivity for the future development of gravitational wave detectors based on large scale atom interferometers. The experiment will be realized at the underground facility of the Laboratoire Souterrain à Bas Bruit (LSBB) in Rustrel-France, an exceptional site located away from major anthropogenic disturbances and showing very low background noise. In the following, we present the measurement principle of an in-cavity atom interferometer, derive the method for Gravitational Wave signal extraction from the antenna and determine the expected strain sensitivity. We then detail the functioning of the different systems of the antenna and describe the properties of the installation site.

Antibiotic resistance and production of inhibitory substances among bacterial strains isolated from the oral cavities of BALB/c mice.

In the oral cavities of BALB/c mice, microbial population levels are regulated by multifactorial processes. Factors include the production of inhibitory substances and the exchange of genetic material. In this work, 371 isolates from different sites (saliva, tongue, teeth, and mucosa) of the oral cavities of BALB/c mice were screened for resistance to antibiotics and antimicrobial activity. Antibiotic-resistant strains represented 25% of the total flora. Among the predominant species, all the S. faecalis isolates showed multiresistance, and 23% of the Lactobacillus murinus isolates and 15% of the Staphylococcus aureus were resistant to at least one antibiotic. Resistance to aminoglycosides (neomycin, streptomycin, kanamycin, and gentamicin) was most frequently encountered. In S. faecalis, high levels of resistance were recorded to neomycin and streptomycin but not to gentamicin or kanamycin. Macrolides (M), lincosamides (L), streptogramin B (S), tetracycline (Tc), and chloramphenicol (Cm) resistance was also present in multiresistance patterns, especially among S. faecalis isolates. Hemolytic (Hly+) streptococci were less resistant to MLS, Tc, and Cm than were non-hemolytic (Hly-) isolates. Resistance to beta-lactam antibiotics was detected only among staphylococci and with a low prevalence (4%). The frequencies of strains producing antimicrobial substances against the indicator strains (S. mutans LG-1, S. sanguis Ny 101, and A. viscosus Ny 1) were high for L. murinus (76%) and S. faecalis (57% for Hly- and 90% for Hly+), but low for S. aureus (7%). These results indicate that the indigenous oral flora could interfere with colonization by allochthonous micro-organisms and that resistance patterns should be taken into account for the elimination of the oral indigenous flora by antibiotic treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of inorganic mercury on the respiration and the swimming activity of shrimp larvae, Pandalus borealis.

In order to test the sensitivity of respiration (physiological and potential) to mercury (Hg) contamination, larval shrimp Pandalus borealis were exposed to inorganic Hg (0-160 ppb) for 27 h in the laboratory. Oxygen consumption rates (RO2), potential respiration (determined by respiratory electron transfer system activity, ETSA), protein content, and swimming activity for zoeae III and zoeae V stages were measured. For both zoeae stages, ETSA and protein content remained constant after 27 h exposure to 160 ppb Hg whereas RO2 and swimming activity decreased. This study revealed the impact of different Hg levels and different exposure times on RO2 of shrimp larvae. After 10 h exposure to 160 ppb Hg, the RO2 decreased by 43 and 49% in zoeae III and zoeae V stages, respectively. Exposure time of 27 h to 80 ppb Hg and higher, induced paralysis in nearly 100% larvae. Surprisingly, the paralysed larvae displayed almost 50% of the control's RO2. The results showed that Hg disturbs a part of the respiration process without modifying the maximum activity of the enzymes involved in the ETSA assay. Therefore, the ETSA assay can not be used as a sublethal bioanalytic probe to detect Hg in short-term exposures. The decline of the RO2/ETSA ratios reported here, indicates an inability of contaminated larvae to adapt their metabolism to physiological stress caused by Hg.

Optimal aeration control in a nitrifying activated sludge process.

An important tool to minimise energy consumption in activated sludge processes is to control the aeration system. Aeration is a costly process and the dissolved oxygen level will determine the efficiency of the operation as well as the treatment results. What aeration control should achieve is closely linked to how the effluent criteria are defined. This paper explores how the aeration process should be controlled to meet the effluent discharge limits in an energy efficient manner in countries where the effluent nitrogen criterion is defined as average values over long time frames, such as months or years. Simulations have been performed using a simplified Benchmark Simulation Model No. 1 to investigate the effect of different levels of suppressing the variations of the effluent ammonium concentration. Optimisation is performed where the manipulated variable for aeration (the oxygen transfer coefficient, K(L)a) is minimised with the constraint that the average daily flow-proportional ammonium concentration in the effluent should reach a desired level. The optimisation results are compared with constant dissolved oxygen concentrations and supervisory ammonium control with different controller settings. The results demonstrate and explain how and why energy consumption can be optimised by tolerating the ammonium concentration to vary around a given average value. In these simulations, the optimal oxygen peak-to-peak amplitude range between 0.7 and 1.8 mg/l depending on the influent variation and ammonium level in the effluent. These variations can be achieved with a slow ammonium feedback controller. The air flow requirements can be reduced by 1-4% compared to constant dissolved oxygen set-points. Optimal control of aeration requires up to 14% less energy than needed for fast feedback control of effluent ammonium.

Bacteriology of the oral cavity of BALB/c mice.

To be used as a model in dental research, an animal must fulfil experimental needs and information on the composition and variation of its oral flora must be available. Only limited data are available on the indigenous oral bacterial flora of BALB/c mice. In this work, a total of 671 isolates from different sites (saliva, tongue, teeth, and mucosa) of the oral cavity of BALB/c mice were identified. Only 18 different species were isolated, which indicates the relative simplicity of the flora. The predominant species of the total cultivable flora were "Lactobacillus murinus" (38%), Staphylococcus aureus (37%), Streptococcus faecalis (8%), Staphylococcus sciuri (4%), and Escherichia coli (3%). The other species each represent less than 2% of the flora. "Lactobacillus murinus" is found in greater proportion on mucosa than in the other sites, Staph. aureus predominates in saliva, and Strep. faecalis was found in greater proportion in tooth samples. Statistical analyses, using the minimum percentage of similarity, indicate that there is some variation among the microflora of different mice but that this difference is smaller for mice from the same lot. These results set the basis for the study of the variations of the indigenous oral microflora of BALB/c mice under different conditions.