Gas sensing based on optical fibre coupled diode laser spectroscopy : a new approach to sensor systems for safety monitoring

We describe an entirely passive fibre optic network which senses, amongst other species, CH¬4¬ and CO¬¬2 , with sensitivity and selectivity compatible with safety sensing in the mine environment. The basic principle is that a single laser diode source targeted to a particular species addresses up to 200 sensing points which may be spread over an area of dimensions ten or more km. The detection and processing electronics is typically located with the laser source. Several laser sources can be introduced in parallel to enable monitoring multiple species. The network itself, entirely linked through optical fibre, is inherently intrinsically safe. It is self checking for faults at the sensing location and continuously self calibrating. In the methane sensing mode its sensitivity is sub 100ppm and it responds accurately up to 100% methane. It is therefore capable of detecting extremely hazardous gas pockets which are completely missed by other sensor technologies. The network has demonstrated stability with zero maintenance or recalibration over periods in excess of two years. We believe that this system offers unique benefits in the context of mine safety and ventilation system monitoring

Human–Black Bear Conflicts: A Review of Common Management Practices

The objective of this monograph is to provide wildlife professionals, who respond to human–bear conflicts, with an appraisal of the most common techniques used for mitigating conflicts as well as the benefits and challenges of each technique in a single document. Most human–black bear conflict occurs when people make anthropogenic foods like garbage, dog food, domestic poultry, or fruit trees available to bears. Bears change their behavior to take advantage of these resources and may damage property or cause public safety concerns in the process. Managers and the public need to understand the available tools to stop human–bear conflict and reduce effects on bear populations.https://digitalcommons.usu.edu/hwi_monographs/1002/thumbnail.jp

Effect of voltage reduction in minimising partial discharge activity in cables - experimental study

A common cause of insulation degradation in high voltage (HV) cables is due to partial discharges (PD). PD may be initiated through imperfections and contaminants present in the insulation. It can be hypothesized that a reduction in system voltage can potentially reduce PD, which will correspondingly extend the service life of the cable. Currently, industry voltage statutory requirements permit ±6% tolerance setting on nominal voltage on distribution networks. Such ±6% voltage reduction on may have little or adverse effect on PD magnitude which depends on the nature of defect. Hence the accuracy and type of measuring PD while reducing system voltage is more critical for this application. Power cable as a low pass filter which attenuates and disperse the PD pulses. In this paper effect of voltage reduction on PD is investigated using standard electrode geometries such as point-plane, point-point and point- rod using IEC60270 measurement system together with frequency domain measurements. It has been observed that PD frequency characteristics at different voltages varies in the wideband frequency spectrum

Detection and prevalence of depression among adult type 2 diabetes mellitus patients attending non-communicable diseases clinics in Lilongwe, Malawi

Background: Depression is associated with chronic physical illnesses and negatively affects health outcomes. However, it often goes undiagnosed and untreated. We investigated the prevalence of depression among adult type 2 diabetes mellitus (T2DM) patients attending non-communicable diseases (NCD) clinics in Lilongwe, Malawi, and estimated the level of routine detection by NCD clinicians. This study set out to determine the prevalence of major depression and its detection among adult type 2 diabetes mellitus (T2DM) patients attending NCD clinics in Lilongwe, Malawi. Methods: In a cross-sectional study design, 323 T2DM patients aged ≥ 18 years were screened for depression with the Patient Health Questionnare-9 (PHQ-9) followed by diagnostic assessment with the Structured Clinical Interview for DSM-IV (SCID). We analysed the association between presence of major depression and sociodemographic factors using logistic regression. Results: Three quarters of the participants (76%) were females. The participants’ ages ranged from 21–79 years. Of the 323 participants, 58 (18%) met criteria for DSM-IV major depression. None of the cases of major depression had been identified by the NCD clinicians. Major depression was found not to be significantly associated with any of the sociodemographic factors. Conclusions: We found that depression is common among NCD clinic attendees with T2DM in Malawi, and poorly detected by NCD clinicians. Given the high prevalence and challenges in clinical identification, integration of depression screening with a standardized validated tool should be a high priority so as to link patients to appropriate services

Pre-determination of partial discharge inception voltage in power cables using electrode gaps in air under AC voltage

The breakdown of insulation in cables while in service can cause considerable damage to equipment and the accessories to which they are connected. PD in cables arises due to the overstressing of cable insulation resulting from electric field enhancement caused by imperfections in cable core and screen. The nature and magnitude of PD activity depends upon the type of defect, aging, environmental factors, applied voltage and cable loading. Reduction in system voltage can potentially reduce PD, which will correspondingly extend the service life of the cable. Currently, industry voltage statutory requirements permit ±6% tolerance setting on nominal voltage on distribution networks. This ±6% voltage reduction on may have little or an adverse effect on PD magnitude depending on the nature of defect present in the cable. Hence there is a clear requirement to pre-determine the PD inception voltage in cables through laboratory experiments to understand the significance of voltage reduction. This means to verify the effect of voltage reduction on extinguishing or minimizing PD activity in cables. In this paper, range of voltages at which PD incepts termed as partial discharge inception voltage(PDIV) is measured using a test cell containing different types of electrode configuration having different spacing. PDIV measured using the test cell is verified by conducting partial discharge testing in paper insulated lead covered (PILC) and cross-linked poly ethylene(XLPE) cables. It has been found that PDIV measured using the test cell and cable are in good agreement

Efficacy, effort, and cost comparisons of trapping and acetaminophen-baiting for control of brown treesnakes on Guam

Brown treesnakes (Boiga irregularis) are an invasive species to the island of Guam. Because they have extirpated the native forest avifauna on Guam and are a threat to other Pacific islands, the development of efficient and cost-effective methods to control them is desired. We compared the efficacy, cost, and effort required to remove brown treesnakes on 6-ha plots in forest scrub on Guam, using 2 methods: trapping and poison baiting. Toxic baits consisted of dead neonatal mice adulterated with 80-mg acetaminophen. To assess efficacy, we used mark-recapture methods to estimate snake abundance on plots 12 days before and 12 days after treatment. We also monitored bait-take or trap success for 20 days during treatment. From 6,304 trap-nights, we recorded 801 captures of 504 snakes on 6, 6-ha plots during a 51-day period. Snake populations on plots ranged from 41 to 107 prior to treatment. Using trapping to gauge survival of marked snakes, the 2 methods (trapping and baiting) had similar efficacies (0.05 to 0.1). Based on trapping, post-treatment population estimates ranged from 26 to 40, yielding reductions from estimated pre-treatment populations of 7 to 68% for both types of snake-removal treatments. Using post-treatment bait-take of unadulterated mice as an index of efficacy, poisoned baiting was twice as effective as trapping in diminishing snake activity. Trapped plots had post-treatment bait-take rates similar to reference plots (75%), whereas poison-baited plots had bait-take rates of 38%, suggesting that some snakes cannot be trapped and that baiting affects a wider range of the snake population. Because of the potential for baiting to impact more snakes, this method was about 1.67 times more cost effective than trapping. If baiting were to occur via aerial drop rather than via bait stations, the economic incentive for using baiting as a control strategy would be even greater. These observations will prove useful for managers making decisions about appropriate methods for control of brown treesnake populations

Citizen science as a new tool in dog cognition research

The work of Á.M. was supported by the Hungarian Academy of Sciences (MTA 01 031).Family dogs and dog owners offer a potentially powerful way to conduct citizen science to answer questions about animal behavior that are difficult to answer with more conventional approaches. Here we evaluate the quality of the first data on dog cognition collected by citizen scientists using the Dognition. com website. We conducted analyses to understand if data generated by over 500 citizen scientists replicates internally and in comparison to previously published findings. Half of participants participated for free while the other half paid for access. The website provided each participant a temperament questionnaire and instructions on how to conduct a series of ten cognitive tests. Participation required internet access, a dog and some common household items. Participants could record their responses on any PC, tablet or smartphone from anywhere in the world and data were retained on servers. Results from citizen scientists and their dogs replicated a number of previously described phenomena from conventional lab-based research. There was little evidence that citizen scientists manipulated their results. To illustrate the potential uses of relatively large samples of citizen science data, we then used factor analysis to examine individual differences across the cognitive tasks. The data were best explained by multiple factors in support of the hypothesis that nonhumans, including dogs, can evolve multiple cognitive domains that vary independently. This analysis suggests that in the future, citizen scientists will generate useful datasets that test hypotheses and answer questions as a complement to conventional laboratory techniques used to study dog psychology.Publisher PDFPeer reviewe