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Introduction: Excessive internet and mobile cell phone use has been increasing in recent years especially in teenagers who are a vulnerable population. However, there is a lack of psychometric evaluation of instruments that allow to identify behavior regarding problematic use of the internet and cell phones in the Latin America, particularly in Ecuador. The main aim of this study is to examine the psychometric properties of two instruments: the Internet-related experiences questionnaire (IREQ) and Mobile-related experiences questionnaire (MREQ) in high school students (n = 4, 174, Mage = 15.63; 51.19% male and 48.37% female). Methods: The validation process was performed using one and two factors for both questionnaires according to previous literature. After checking the models proposed to date, the best fit model was the one-factor model for (IREQ) and one-factor model for (MREQ). Results and discussion: The invariance was performed using two samples according to gender (male, female) and has been confirmed with an acceptable internal consistency for both questionnaires. For IREQ (All, ω = 0.80; Male, ω = 0.77; Female, ω = 0.82) and for MREQ (All, ω = 0.83; Male, ω = 0.82; Female, ω = 0.84). In addition, we performed the correlation analysis between IREQ, MREQ, and socio-demographic variables and finally, both instruments demonstrated strong psychometric qualities within the local population. [ABSTRACT FROM AUTHOR]

IntroductionExcessive internet and mobile cell phone use has been increasing in recent years especially in teenagers who are a vulnerable population. However, there is a lack of psychometric evaluation of instruments that allow to identify behavior regarding problematic use of the internet and cell phones in the Latin America, particularly in Ecuador. The main aim of this study is to examine the psychometric properties of two instruments: the Internet-related experiences questionnaire (IREQ) and Mobile-related experiences questionnaire (MREQ) in high school students (n = 4, 174, Mage = 15.63; 51.19% male and 48.37% female).MethodsThe validation process was performed using one and two factors for both questionnaires according to previous literature. After checking the models proposed to date, the best fit model was the one-factor model for (IREQ) and one-factor model for (MREQ).Results and discussionThe invariance was performed using two samples according to gender (male, female) and has been confirmed with an acceptable internal consistency for both questionnaires. For IREQ (All, ω = 0.80; Male, ω = 0.77; Female, ω = 0.82) and for MREQ (All, ω = 0.83; Male, ω = 0.82; Female, ω = 0.84). In addition, we performed the correlation analysis between IREQ, MREQ, and socio-demographic variables and finally, both instruments demonstrated strong psychometric qualities within the local population.

• A comparative study of five working protocols in freezing chambers. • Research sustained by field measurements. • Application of a thoroughly validated thermoregulation model. • Useful guidelines for working safely in cold environments are provided. • Two protocols were identified where workers' thermal stress is nearly neutral. Working in freezing chambers involves alternating between very cold and warm environments, posing health and safety risks. Despite this, human thermophysiological responses in such conditions are under-assessed. This study evaluates cold stress in freezing chambers using field measurements and a thermophysiological model. Useful guidelines for improvement of protective clothing and of working periods in both environments are provided. The field study reveals that workers' clothing often lacks sufficient insulation, risking whole-body cooling. The thermoregulation model is used to compare the current most often working conditions in freezing chambers with four other scenarios where more appropriate clothing or exposure times are employed. For instance, to maintain current exposure times, basic clothing insulation must increase from 0.24 to 0.35 m2 K W-1 (from ≈ 1.6 to ≈ 2.3 clo). Alternatively, with existing clothing, cold exposure should be limited to 18 minutes and warm exposure must be at least 18 min. [ABSTRACT FROM AUTHOR]

Background: Cardiovascular (CV) and thermal responses to metabolically demanding multi-day military operations in extreme cold-weather environments are not well described. Characterization of these operations will provide greater insights into possible performance capabilities and cold injury risk. Methods: Soldiers from two cold-weather field training exercises (FTX) were studied during 3-day (study 1, n = 18, age: 20 ± 1 year, height: 182 ± 7 cm, mass: 82 ± 9 kg) and 4-day (study 2, n = 10, age: 20 ± 1 year, height: 182 ± 6 cm, mass: 80.7 ± 8.3 kg) ski marches in the Arctic. Ambient temperature ranged from −18 to −4 °C during both studies. Total daily energy expenditure (TDEE, from doubly labeled water), heart rate (HR), deep body ( T ), and torso ( T ) skin temperature (obtained in studies 1 and 2) as well as finger ( T ), toe ( T ), wrist, and calf temperatures (study 2) were measured. Results: TDEE was 6821 ± 578 kcal day and 6394 ± 544 for study 1 and study 2, respectively. Mean HR ranged from 120 to 140 bpm and mean T ranged between 37.5 and 38.0 °C during skiing in both studies. At rest, mean T ranged from 36.0 to 36.5 °C, (lowest value recorded was 35.5 °C). Mean T ranged from 32 to 35 °C during exercise and dropped to 15 °C during rest, with some T values as low as 6-10 °C. T was above 30 °C during skiing but dropped to 15-20 °C during rest. Conclusions: Daily energy expenditures were among the highest observed for a military training exercise, with moderate exercise intensity levels (~65% age-predicted maximal HR) observed. The short-term cold-weather training did not elicit high CV and T strain. T and T were also well maintained while skiing, but decreased to values associated with thermal discomfort at rest. [ABSTRACT FROM AUTHOR]

Working in cold environments can have a variety of negative consequences on health, efficiency, quality, safety, and performance. The present study investigates the risk of cold stress in petroleum transfer centers in Iran's northwestern cold regions. The proposed method by ISO-15743 (E) was used to assess the risk of cold stress. The activity level (M) was calculated using the ISO 8996:2021 standard. The evaluation of local cooling, contact of cold surfaces, and hand and face temperature was performed using ISO 11079, ISO 13732–3, and ISO 9886, respectively. During their work, 28 outdoor site men and mechanics as a case group and 8 operators as a control group put through subjective analysis. According to the findings, the mean I cl,r , IREQ min, and IREQ neutral were 1.59 ± 0.33, 2.1 ± 0.44, and 2.43 ± 0.45, respectively. The mean equivalent chill temperature was −13.83 ± 5.45, and workers were at risk of local cooling stress at levels 1 and 2. The case group showed greater losses in finger skin temperatures after short term exposure to extremely cold environments than the control group (P < 0.001). Based on the questionnaire results a significant percentage of workers performing the activity during the winter have more difficulty. Prolonged general and local cold exposure can cause pain, numbness, and frostbite in site men and mechanics. Careful planning, training, extensive distribution of cold protective clothing, rest periods, a relatively short stay in the cold environment, and proper equipment can greatly reduce these hazards. • The risk of cold stress in petroleum transfer centers was investigated. • The clothing did not provide adequate insulation against the cold. • The mechanic workers finger temperature fell below 25 °C on working days. • Prolonged general and local cold exposure can cause pain, numbness, and frostbite. • Workers for contact periods touching steel, are at high risk of cold stress. [ABSTRACT FROM AUTHOR]

During normal lifetime, transformers are submitted to a variety of electrical, mechanical and thermal stresses. One of the most critical situations is that caused by external short circuits, which produces high currents in the transformer windings and hence high internal forces in the windings. These forces are potential sources for damaging transformers. In this paper the different parameters for short circuit withstand capability of a transformer is calculated considering a 1500KVA, 22KV/415V, Dyn11 Distribution Transformer. The short circuit withstand test of a Transformer cannot be performed in the Test Laboratory of any manufacturer. There is a need for a high test field power, especially for large units with ratings of 100MVA and above. The tests can only be performed at a few powerful test stations, such as those operated in KEMA (Netherlands), EDF (France), CESI (Italy) or IREQ (Canada). Short circuit tests are expensive. The cost of the test itself is high. The cost also increases due to activities such as, transporting the transformer under test from the factory, local installation at the test laboratory and again at the factory, untanking and inspection, repetition of dielectric tests etc. For this reason the IEC standards also permits demonstration of the short circuit ability using calculation and design considerations. [ABSTRACT FROM AUTHOR]

Most routing protocols in mobile ad hoc networks (MANETs) place an emphasis on finding paths in dynamic networks without considering security. As a result, there are a number of attacks that can be used to manipulate the routing in MANET. A malicious node that sends a modified control message to an intermediate node can disturb the network using a control message. To solve this problem, we introduce AODV protocol with route investigation procedure (AODV-RIP). It uses two additional control messages to defeat security attacks that can occur in AODV routing protocol. When an intermediate node that is on the path between the source node and the destination node receives a control message, it sends a Rroute Investigation Request (IREQ) message to the destination node in order to check the reliability of the control message. According to the existence of Route Investigation Reply (IREP), the intermediate node decides whether it transmits the control message to the source node or not. Consequently, the intermediate node that receives the control message confirms that it is using two additive control messages: IREQ and IREP. Through this investigation procedure, the source node can obtain a reliable path for transmitting data packets to an intentional destination node. The simulation results show an improvement in the packet delivery ratio and end-to-end delay at the expense of a moderate increase of the control message overhead compared with the current routing protocols. Copyright © 2009 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This study investigated the usefulness of continuous sensor data for improving occupational cold stress assessment. Eleven volunteer male subjects completed a 90-120-min protocol in cold environments, consisting of rest, moderate and hard work. Biomedical data were measured using a smart jacket with integrated temperature, humidity and activity sensors, in addition to a custom-made sensor belt worn around the chest. Other relevant sensor data were measured using commercially available sensors. The study aimed to improve decision support for workers in cold climates, by taking advantage of the information provided by data from the rapidly growing market of wearable sensors. Important findings were that the subjective thermal sensation did not correspond to the measured absolute skin temperature and that large differences were observed in both metabolic energy production and skin temperatures under identical exposure conditions. Temperature, humidity, activity and heart rate were found to be relevant parameters for cold stress assessment, and the locations of the sensors in the prototype jacket were adequate. The study reveals the need for cold stress assessment and indicates that a generalised approached is not sufficient to assess the stress on an individual level.