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Sala, Gianluca, Camilla Lanfranconi, Paolo Frattini, Giulia Rusconi et Giovanni B. Crosta. « Cost-sensitive rainfall thresholds for shallow landslides ». Landslides 18, no 9 (17 juin 2021) : 2979–92. http://dx.doi.org/10.1007/s10346-021-01707-4.
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AbstractThe risk management of rainfall-induced landslides requires reliable rainfall thresholds to issue early warning alerts. The practical application of these thresholds often leads to misclassifications, either false negative or false positive, which induce costs for the society. Since missed-alarm (false negative) and false-alarm (false positive) cost may be significantly different, it is necessary to find an optimal threshold that accounts for and minimises such costs, tuning the false-alarm and missed-alarm rates. In this paper, we propose a new methodology to develop cost-sensitive rainfall thresholds, and we also analyse several factors that produce uncertainty, such as the accuracy of rainfall intensity values at landslide location, the time of occurrence, the minimum rainfall amount to define the non-triggering event, and the variability of cost scenarios. Starting from a detailed mapping of landslides that occurred during five large-scale rainfall events in the Italian Central Alps, we first developed rainfall threshold curves with a ROC-based approach by using both rain gauge and bias-adjusted weather radar data. Then, based on a reference cost scenario in which we quantified several cost items for both missed alarms and false alarms, we developed cost-sensitive rainfall threshold curves by using cost-curve approach (Drummond and Holte 2000). Finally, we studied the sensitivity of cost items. The study confirms how important is the information regarding rainfall intensity at the landslide site for the development of rainfall thresholds. Although the use of bias-corrected radar strongly improves these values, a large uncertainty related to the exact time of landslide occurrence still remains, negatively affecting the analysis. Accounting for the different missed-alarm and false-alarm misclassification costs is important because different combinations of these costs make an increase or decrease of the rainfall thresholds convenient. In our reference cost scenario, the most convenient threshold is lower than ROC-based thresholds because it seeks to minimise the number of missed alarms, whereas the missed-alarm costs are almost seven times greater than false-alarm costs. However, for different cost scenarios, threshold may vary significantly, as much as half an order of magnitude.
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Roy, Nihar Ranjan, et Pravin Chandra. « Threshold sensitive clustering in SEP ». Sustainable Computing : Informatics and Systems 25 (mars 2020) : 100367. http://dx.doi.org/10.1016/j.suscom.2019.100367.
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Mu, Yi, et C. M. Savage. « Phase-sensitive above-threshold laser amplifiers ». Physical Review A 49, no 5 (1 mai 1994) : 4093–100. http://dx.doi.org/10.1103/physreva.49.4093.
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Ferreira, Guilherme A., Romulo Bertuzzi, Adriano E. Lima-Silva, Carlos Malfatti, Fernando R. De-Oliveira et Raul Osiecki. « Identification of training status differences using perceived exertion threshold ». Applied Physiology, Nutrition, and Metabolism 41, no 4 (avril 2016) : 456–59. http://dx.doi.org/10.1139/apnm-2015-0478.
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We investigated if the rate of perceived exertion (RPE) threshold is as sensitive as the lactate threshold to detect training differences. Lactate and RPE thresholds were identified in well-trained cyclists and physically active males. Power output was higher in well-trained cyclists than in physically active individuals for both thresholds (p < 0.05). Our results suggest that RPE threshold is successful in discriminating differences between well-trained cyclists and physically active individuals.
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Pflug, Justin M., Yiwen Fang, Steven A. Margulis et Ben Livneh. « Interactions between thresholds and spatial discretizations of snow : insights from estimates of wolverine denning habitat in the Colorado Rocky Mountains ». Hydrology and Earth System Sciences 27, no 14 (24 juillet 2023) : 2747–62. http://dx.doi.org/10.5194/hess-27-2747-2023.
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Abstract. Thresholds can be used to interpret environmental data in a way that is easily communicated and useful for decision-making purposes. However, thresholds are often developed for specific data products and time periods, changing findings when the same threshold is applied to datasets or periods with different characteristics. Here, we test the impact of different spatial discretizations of snow on annual estimates of wolverine denning opportunities in the Colorado Rocky Mountains, defined using a snow water equivalent (SWE) threshold (0.20 m) and threshold date (15 May) from previous habitat assessments. Annual potential wolverine denning area (PWDA) was thresholded from a 36-year (1985–2020) snow reanalysis model with three different spatial discretizations: (1) 480 m grid cells (D480), (2) 90 m grid cells (D90), and (3) 480 m grid cells with implicit representations of subgrid snow spatial heterogeneity (S480). Relative to the D480 and S480 discretizations, D90 resolved shallower snow deposits on slopes between 3050 and 3350 m elevation, decreasing PWDA by 10 %, on average. In years with warmer and/or drier winters, S480 discretizations with subgrid representations of snow heterogeneity increased PWDA, even within grid cells where mean 15 May SWE was less than the SWE threshold. These simulations increased PWDA by upwards of 30 % in low-snow years, as compared to the D480 and D90 simulations without subgrid snow heterogeneity. Despite PWDA sensitivity to different snow spatial discretizations, PWDA was controlled more by annual variations in winter precipitation and temperature. However, small changes to the SWE threshold (±0.07 m) and threshold date (±2 weeks) also affected PWDA by as much as 82 %. Across these threshold ranges, PWDA was approximately 18 % more sensitive to the SWE threshold than the threshold date. However, the sensitivity to the threshold date was larger in years with late spring snowfall, when PWDA depended on whether modeled SWE was thresholded before, during, or after spring snow accumulation. Our results demonstrate that snow thresholds are useful but may not always provide a complete picture of the annual variability in snow-adapted wildlife denning opportunities. Studies thresholding spatiotemporal datasets could be improved by including (1) information about the fidelity of thresholds across multiple spatial discretizations and (2) uncertainties related to ranges of realistic thresholds.
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Kalogianni, E. « Physiological properties of wind-sensitive and tactile trichoid sensilla on the ovipositor and their role during oviposition in the locust ». Journal of Experimental Biology 198, no 6 (1 juin 1995) : 1359–69. http://dx.doi.org/10.1242/jeb.198.6.1359.
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The physiological properties of the ovipositor hair sensilla of the desert locust and their responses to wind and to direct mechanical displacement are described. The hairs on the external surfaces of the ventral and dorsal ovipositor valves respond to wind stimulation, whereas the hairs on the inner surfaces of the dorsal valves are not wind-sensitive. All ovipositor hairs, however, respond to tactile displacement. Imposed tactile stimulation reveals two physiologically distinct types of ovipositor tactile hairs: the hairs on the inner surface of the dorsal valves are high-threshold hairs (threshold angular deflection of 26­67 ° at 1 Hz) that respond phasically, whereas the hairs on the lateral and ventral areas of the ventral valves and the lateral areas of the dorsal valves are low-threshold hairs (threshold angular deflection of 6­20 ° at 1 Hz) that respond phasotonically. There is no apparent difference in the length of the two physiologically distinct types of hairs. Both high- and low-threshold hairs are directionally sensitive, with maximal responses to proximal deflection, towards the abdomen, and are also velocity-sensitive. High-threshold hairs have velocity thresholds of 40­50 ° s-1 for some hairs and 110­140 ° s-1 for others for a deflection angle of 35 °, whereas low-threshold hairs have lower velocity thresholds of less than 5 ° s-1 for the same deflection. High-threshold hairs adapt rapidly to repetitive stimulation after as few as four cycles of stimulation at 0.5 Hz. Low-threshold hairs continue to respond after 40 cycles of stimulation at 0.5 Hz and show little adaptation to repetitive stimulation at frequencies ranging from 0.1 to 5 Hz. Low-threshold hairs respond with bursts of spikes at frequencies that reflect both the velocity and the duration of the stimulus. Furthermore, low-threshold hairs show little adaptation after 30 min of stimulation that simulates oviposition digging. It is suggested (a) that low- and high-threshold ovipositor hairs detect phasic wind and/or tactile stimuli in non-ovipositing locusts and (b) that low-threshold hairs can also signal rhythmic tactile inputs during oviposition digging.
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Zhang, Yuan, Xiao-Ning Wang, Hai-Yu Ding, Yang Dai, Sen Ding et Xin Gao. « Threshold Responses in the Taxonomic and Functional Structure of Fish Assemblages to Land Use and Water Quality : A Case Study from the Taizi River ». Water 11, no 4 (30 mars 2019) : 661. http://dx.doi.org/10.3390/w11040661.
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Biological functional traits help to understand specific stressors that are ignored intaxonomic data analysis. A combination of biological functional traits and taxonomic data ishelpful in determining specific stressors which are of significance for fish conservation and riverbasin management. In the current study, the Taizi River was used as a case study to understand therelationships between the taxonomic and functional structure of fish and land use and waterquality, in addition to determining the thresholds of these stressors. The results showed thattaxonomic structure was significantly affected by the proportion of urban land and specificconductivity levels, while functional metrics were influenced by the proportions of farmland andforest. Threshold indicator taxa analysis found that Phoxinus lagowskii, Barbatula barbatula nuda,Odontobutis obscura, and Cobitis granoei had negative threshold responses along the gradients ofurban developments and specific conductivity. There was a significant change in fish taxonomiccomposition when the proportion of urban land exceeded a threshold of 2.6–3.1%, or specificconductivity exceeded a threshold of 369.5–484.5 μS/cm. Three functional features—habitatpreference, tolerance to disturbances, and spawning traits—showed threshold responses to theproportion of farmland and forest. The abundance of sensitive species should be monitored as partof watershed management, as sensitive species exhibit an earlier and stronger response to stressorsthan other functional metrics. Sensitive species had a positive threshold response to the proportionof forest at 80.1%. These species exhibited a negative threshold response to the proportion offarmland at 13.3%. The results of the current study suggest that the taxonomic and functionalstructure of fish assemblages are affected by land use and water quality. These parameters shouldbe integrated into routine monitoring for fish conservation and river basin management in the TaiziRiver. In addition, corresponding measures for improving river habitat and water quality shouldbe implemented according to the thresholds of these parameters.
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Mair, I. W. S., et E. Laukli. « Air Conduction Thresholds after Myringoplasty and Stapes Surgery : A Conventional and High Frequency Audiometric Comparison ». Annals of Otology, Rhinology & ; Laryngology 95, no 4 (juillet 1986) : 327–30. http://dx.doi.org/10.1177/000348948609500402.
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A comparison has been made of air conduction thresholds after myringoplasty and stapes surgery for otosclerosis in both the conventional (0.25 to 8 kHz) and high frequency (8 to 20 kHz) ranges. Significant threshold losses occurred in the high frequencies following both procedures. Threshold improvement was significantly greater at the lower frequencies following stapes surgery, while high frequency threshold deterioration was significantly less in the myringoplasty group. High frequency audiometry may prove to be a sensitive monitor of middle ear surgical techniques.
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LOOP, MICHAEL S., et DAVID K. CROSSMAN. « High color-vision sensitivity in macaque and humans ». Visual Neuroscience 17, no 1 (janvier 2000) : 119–25. http://dx.doi.org/10.1017/s0952523800171123.
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Psychophysical (behavioral) detection thresholds and color-discrimination thresholds were determined in a macaque using a two-alternative forced-choice procedure. On a white background, detection thresholds were determined for a white increment and three spectral increments: 618, 516, and 456 nm. Intermixed with detection threshold determinations, color-discrimination thresholds were determined by presenting the white increment, and one of the spectral increments, at 1.0 log units above their respective detection thresholds and dimming both until discrimination performance fell to threshold. The monkey could discriminate the color of the increments at detection threshold because the average color-discrimination threshold was 0.98 ± 0.14 log attenuation. Because the monkey was much more sensitive to the spectral increments than the white increment, we performed an unconventional experiment. We determined the monkey's detection threshold for the white increment alone, and with broadband color filters in the white light path without adjusting the light's intensity. Insertion of several color filters in the light path lowered detection thresholds of both the macaque and six human trichromats. We believe that this improvement in detection thresholds produced by simply inserting color filters in a white light path is a threshold manifestation of the Helmholtz-Kohlrausch effect and suggests that one of color vision's important evolutionary advantages may be improved detection sensitivity.
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Polena, Helena, Marlène Chavagnac-Bonneville, Laurent Misery et Michèle Sayag. « Burden of Sensitive Skin (BoSS) Questionnaire and Current Perception Threshold : Use as Diagnostic Tools for Sensitive Skin Syndrome ». Acta Dermato-Venereologica 101, no 11 (30 novembre 2021) : adv00606. http://dx.doi.org/10.2340/actadv.v101.365.
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The assessment of sensitive skin syndrome, characterized by subjective unpleasant sensations, remains a challenge, since there is no international consensus on the best diagnostic tools. This study evaluated the combination of the Burden of Sensitive Skin (BoSS) questionnaire and the current perception threshold as diagnostic tools for sensitive skin syndrome, and the relationship between BoSS and the subjects’ smoking status, phototype and skin type. A total of 100 women completed the BoSS questionnaire, and current perception threshold was measured on the face. The BoSS score was significantly higher in the self-reported sensitive skin group compared with the non-sensitive skin group (25.61 vs 14.05; p < 0.001), and in non-smokers vs smokers (23.00 vs 18.37; p < 0.05). In addition, the current perception threshold values were similar between the sensitive and non-sensitive groups. These results suggest that BoSS is a better diagnostic tool for sensitive skin syndrome than the current perception threshold, and that smokers less frequently have sensitive skin than do non-smokers.
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Feng, Bin, Pablo R. Brumovsky et Gerald F. Gebhart. « Differential roles of stretch-sensitive pelvic nerve afferents innervating mouse distal colon and rectum ». American Journal of Physiology-Gastrointestinal and Liver Physiology 298, no 3 (mars 2010) : G402—G409. http://dx.doi.org/10.1152/ajpgi.00487.2009.
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Information about colorectal distension (i.e., colorectal dilation by increased intraluminal pressure) is primarily encoded by stretch-sensitive colorectal afferents in the pelvic nerve (PN). Despite anatomic differences between rectum and distal colon, little is known about the functional roles of colonic vs. rectal afferents in the PN pathway or the quantitative nature of mechanosensory encoding. We utilized an in vitro mouse colorectum-PN preparation to investigate pressure-encoding characteristics of colorectal afferents. The colorectum with PN attached was dissected, opened longitudinally, and pinned flat in a Sylgard-lined chamber. Action potentials of afferent fibers evoked by circumferential stretch (servo-controlled force actuator) were recorded from the PN. Stretch-sensitive fibers were categorized into the following four groups: colonic muscular, colonic muscular/mucosal, rectal muscular, and rectal muscular/mucosal. Seventy-nine stretch-sensitive PN afferents evenly distributed into the above four groups were studied. Rectal muscular afferents had significantly greater stretch-responses than the other three groups. Virtually all rectal afferents (98%) had low thresholds for response and encoded stimulus intensity into the noxious range without obvious saturation. Most colonic afferents (72%) also had low thresholds (<14 mmHg), but a significant proportion (28%) had high thresholds (>18 mmHg) for response. These high-threshold colonic afferents were sensitized to stretch by inflammatory soup; response threshold was significantly reduced (from 23 to 12 mmHg), and response magnitude significantly increased. These results suggest that the encoding of mechanosensory information differs between colonic and rectal stretch-sensitive PN afferents. Rectal afferents have a wide response range to stretch, whereas high-threshold colonic afferents likely contribute to visceral nociception.
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Savill, Nicholas J., Suzanne G. St. Rose et Mark E. J. Woolhouse. « Detection of mortality clusters associated with highly pathogenic avian influenza in poultry : a theoretical analysis ». Journal of The Royal Society Interface 5, no 29 (13 mai 2008) : 1409–19. http://dx.doi.org/10.1098/rsif.2008.0133.
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Rapid detection of infectious disease outbreaks is often crucial for their effective control. One example is highly pathogenic avian influenza (HPAI) such as H5N1 in commercial poultry flocks. There are no quantitative data, however, on how quickly the effects of HPAI infection in poultry flocks can be detected. Here, we study, using an individual-based mathematical model, time to detection in chicken flocks. Detection is triggered when mortality, food or water intake or egg production in layers pass recommended thresholds suggested from the experience of past HPAI outbreaks. We suggest a new threshold for caged flocks—the cage mortality detection threshold—as a more sensitive threshold than current ones. Time to detection is shown to depend nonlinearly on R 0 and is particularly sensitive for R 0 <10. It also depends logarithmically on flock size and number of birds per cage. We also examine how many false alarms occur in uninfected flocks when we vary detection thresholds owing to background mortality. The false alarm rate is shown to be sensitive to detection thresholds, dependent on flock size and background mortality and independent of the length of the production cycle. We suggest that current detection thresholds appear sufficient to rapidly detect the effects of a high R 0 HPAI strain such as H7N7 over a wide range of flock sizes. Time to detection of the effects of a low R 0 HPAI strain such as H5N1 can be significantly improved, particularly for large flocks, by lowering detection thresholds, and this can be accomplished without causing excessive false alarms in uninfected flocks. The results are discussed in terms of optimizing the design of disease surveillance programmes in general.
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Landström, Ulf, et Ronnie Lundström. « Sensations, Perception Thresholds and Temporary Threshold Shifts of Whole Body Vibrations in Sitting and Standing Posture ». Journal of Low Frequency Noise, Vibration and Active Control 5, no 2 (juin 1986) : 68–77. http://dx.doi.org/10.1177/026309238600500203.
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The experiments were conducted to evaluate the subjective experience associated with sinusoidal whole body vibration. Exposures were carried out in vertical (z) direction with the subject placed in upright sitting and standing positions. According to the present results, the vibration perception level is approximately the same for both postures, about 80–90 dB, (re 1 μm/s2 (r.m.s)) when comparing frequencies below 100 Hz. The threshold values were found to be influenced by the body weight, heavy people being more sensitive to whole body vibration in sitting posture, light people being more sensitive to vibrations in standing posture. Furthermore, the present study clearly shows the existence of temporary threshold shifts (TTS) in perception of whole body vibration after 5 minutes of vibration fatigue. If measured c. 30 seconds after the end of the exposure the temporary threshold shifts were in the magnitude of 10 dB.
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Newland, P. L. « Physiological properties of afferents from tactile hairs on the hindlegs of the locust ». Journal of Experimental Biology 155, no 1 (1 janvier 1991) : 487–503. http://dx.doi.org/10.1242/jeb.155.1.487.
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1. The spatial distribution and physiological properties of the tactile hairs and their sensory afferents of the hindlegs of the locust Schistocerca gregaria are described. Hairs occur in a consistent position from animal to animal. Hairs on the dorsal tibia are of a greater mean length, 403.1 +/− 17.9 microns, than hairs on the ventral tibia, 265.2 +/− 10.44 microns. Hairs on the dorsal and ventral femur are approximately 310 microns long and hairs on the tarsus are shorter, approximately 200 microns. 2. Based on their threshold responses to sinusoidal mechanical stimulation, the tactile hairs are of two basic physiological types. High-threshold hairs occur only on the proximal dorsal tibia and at the proximal base of each tibial spine, whereas low-threshold hairs are found on the femur, tibia and tarsus. 3. High-threshold hair afferents respond phasically to imposed deflections of the hair shaft and have mean velocity thresholds of 21.1 +/− 4.2 degrees s-1. They adapt rapidly to repetitive stimulation, after as few as 11 cycles at 5 Hz. Low-threshold hairs respond in a more phaso-tonic manner to imposed deflections and have velocity thresholds of less than 3 degrees s-1. They adapt to repetitive stimulation at a similar rate to the high-threshold hairs, but continue to respond to stimulation after 200 cycles at 5 Hz. 4. All the hairs are directionally sensitive, with the preferred direction being oriented proximally and medially (i.e. proximally and towards the body); they are least sensitive to deflections in the opposite direction.
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Rompré, Ghislain, Yan Boucher, Louis Bélanger, Sylvie Côté et W. Douglas Robinson. « Conservation de la biodiversité dans les paysages forestiers aménagés : utilisation des seuils critiques d’habitat ». Forestry Chronicle 86, no 5 (1 septembre 2010) : 572–79. http://dx.doi.org/10.5558/tfc86572-5.
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In Canada, as in other large forested countries of the world, managers and scientists alike question what can happen to forest biodiversity under long-term industrial forest management. Recent studies may help us understand how species react when habitat is lost past a certain threshold in the landscape. In the case of population, a “critical threshold for habitat” does exist in forested habitat, which is defined by the minimal proportion of habitat needed to be preserved to avoid drastic population declines or massive species loss. In this paper, two types of thresholds are described, the first refers to population, and the second refers to the community of species. Many ecologists agree with the assumption that the specialist, sensitive species are the first to disappear (local extirpation for specialist species). For most species with large home range (such as birds), the threshold may generally be located between 30% and 40% of the habitat still remaining, compared to the proportion observed under a natural disturbance regime. We suggest, in order to protect the most sensitive species and to deal with uncertainty associated with thresholds, to maintain at least 40% of residual habitats. Although there is still much to understand concerning these thresholds, we nevertheless recommend their use for the diagnostic analysis that must be performed in the context of forest management planning and biodiversity conservation, as these thresholds could represent the minimal proportion of habitat to preserve integrity of the forest ecosystem. However, to be effective, the application of thresholds should be based on detailed knowledge of ecosystem characteristics and dynamics. Key words: ecological threshold, forest management, forest ecosystem, habitat loss, mature and old forests, population, community, biodiversity, conservation
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Rompré, Ghislain, Yan Boucher, Louis Bélanger, Sylvie Côté et W. Douglas Robinson. « Conserving biodiversity in managed forest landscapes : The use of critical thresholds for habitat ». Forestry Chronicle 86, no 5 (1 septembre 2010) : 589–96. http://dx.doi.org/10.5558/tfc86589-5.
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In Canada, as in other large forested countries of the world, managers and scientists alike question what can happen to forest biodiversity under long-term industrial forest management. Recent studies may help us understand how species react when habitat is lost past a certain threshold in the landscape. In the case of population, a “critical threshold for habitat” does exist in forested habitat, which is defined by the minimal proportion of habitat needed to be preserved to avoid drastic population declines or massive species loss. In this paper, two types of thresholds are described, the first refers to population, and the second refers to the community of species. Many ecologists agree with the assumption that the specialist, sensitive species are the first to disappear (local extirpation for specialist species). For most species with large home range (such as birds), the threshold may generally be located between 30% and 40% of the habitat still remaining, compared to the proportion observed under a natural disturbance regime. We suggest, in order to protect the most sensitive species and to deal with uncertainty associated with thresholds, to maintain at least 40% of residual habitats. Although there is still much to understand concerning these thresholds, we nevertheless recommend their use for the diagnostic analysis that must be performed in the context of forest management planning and biodiversity conservation, as these thresholds could represent the minimal proportion of habitat to preserve integrity of the forest ecosystem. However, to be effective, the application of thresholds should be based on detailed knowledge of ecosystem characteristics and dynamics. Key words: ecological threshold, forest management, forest ecosystem, habitat loss, older or late-seral forests, population, community, biodiversity, conservation
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Wrobel, Bozena B., Alexander G. Bien, Eric H. Holbrook, George E. Meyer, Neil A. Bratney, Jane Meza et Donald A. Leopold. « Decreased Nasal Mucosal Sensitivity in Older Subjects ». American Journal of Rhinology 20, no 3 (mai 2006) : 364–68. http://dx.doi.org/10.2500/ajr.2006.20.2862.
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Background The sensitivity of the human nasal cavity mucosa to touch is not well understood. The site of receptors and mode of action responsible for the sensation of the nasal airflow is a topic of controversy. Previous studies have suggested that the skin-lined nasal vestibule is more sensitive to airflow than the mucosa of the nasal cavity. A possible decline in nasal sensitivity to airflow in older subjects has not been studied. Methods The threshold of the mucosal sensitivity to jets of air was assessed in 76 subjects with healthy nasal cavities. A total of 141 nostrils were tested, 67 in younger patients and 74 in older patients. Results Statistically significant (p < 0.001) increases in thresholds were found for all points tested for older patients compared with the younger patients. In general, the more sensitive locations were in the nasal vestibule. The nasal cavity mucosa in the inferior meatus was slightly more sensitive than the middle meatus. Conclusion We have measured the threshold to touch (air jet sensitivity) in nine places in each of 141 nasal cavities and determined that the variability and sensitivity of these measurements among people varies by age and the distance from the nostril. Older subjects were found to have a higher threshold for the sensation of air flow, and the nasal vestibule was found to be more sensitive than the rest of the nasal cavity mucosa with the inferior meatus slightly more sensitive then the middle meatus.
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Sun, Hong-Tao, Jinming Huang, Zhi Chen et Zhiwen Wang. « State-sensitive event-triggered path following control of autonomous ground vehicles ». Intelligence & ; Robotics 3, no 3 (20 juillet 2023) : 257–73. http://dx.doi.org/10.20517/ir.2023.17.
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This paper investigates an improved event-triggered control based on the perception of state measurement for path following control of autonomous ground vehicles. Firstly, in order to regulate the event-triggered thresholds dynamically, a barrier-like function is first used to develop such a novel state-sensitive event-triggered communication (SS-ETC) scheme. Different from the existing variable-threshold ETC schemes, the proposed SS-ETC incorporates the state measurements directly in the event threshold adjustment, eliminating the need for additional terms or dynamics introduced in previous works. Secondly, the networked path following control modeling issues, which include both physical dynamics and the SS-ETC scheme, are characterized by the input delay approach. The controller design method is well derived, ensuring the preservation of input-to-state stability of the path following control system. The main advantage of this paper lies in the proposed SS-ETC, which shows a better trade-off between control and communication. Finally, several simulation experiments are conducted to verify the effectiveness of the proposed event-triggered control scheme.
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Rai, Shailie, et Pallavi Gupta. « Implementation and Analysis of Threshold Sensitive Stable Election Protocol ». IJARCCE 6, no 4 (30 avril 2017) : 217–23. http://dx.doi.org/10.17148/ijarcce.2017.6441.
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Lychagin, E. V., S. G. Novikov et N. T. Gurin. « A threshold position-sensitive photoswitch with negative differential resistance ». Russian Microelectronics 42, no 7 (7 novembre 2013) : 373–77. http://dx.doi.org/10.1134/s1063739712070086.
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Zhao, Huimin. « Instance weighting versus threshold adjusting for cost-sensitive classification ». Knowledge and Information Systems 15, no 3 (3 avril 2007) : 321–34. http://dx.doi.org/10.1007/s10115-007-0079-1.
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Pejovic, Milic, Momcilo Pejovic et Aleksandar Jaksic. « Radiation-sensitive field effect transistor response to gamma-ray irradiation ». Nuclear Technology and Radiation Protection 26, no 1 (2011) : 25–31. http://dx.doi.org/10.2298/ntrp1101025p.
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The influence of gate bias during gamma-ray irradiation on the threshold voltage shift of radiation sensitive p-channel MOSFETs determined on the basis of transfer characteristics in saturation has been investigated. It has been shown that for the gate bias during the irradiation of 5 V and 10 V the sensitivity of these transistors can be presented as the threshold voltage shift and the absorbed irradiation dose ratio. On the bases of the subthreshold characteristics and transfer characteristics in saturation using the midgap technique we have determined the densities of radiation induced oxide traps and interface traps responsible for the threshold voltage shift. In addition, the charge pumping technique was used to determine the energy density of true interface traps. It has been shown that radiation-induced oxide traps have dominant role on threshold voltage shift, especially for gate biases during the irradiation of 5 V and 10 V.
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Hawryshyn, Craig W. « Light-adaptation properties of the ultraviolet-sensitive cone mechanism in comparison to the other receptor mechanisms of goldfish ». Visual Neuroscience 6, no 4 (avril 1991) : 293–301. http://dx.doi.org/10.1017/s0952523800006544.
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AbstractThe light-adaptation properties of goldfish photoreceptor mechanisms were examined using Stiles' two-color threshold technique. Threshold vs. background intensity (TVI) curves were determined for isolated cone and rod mechanisms using the heart-rate conditioning technique. The principal aim of this study was to compare the light-adaptation properties of the ultraviolet (UV)-sensitive cone mechanism to the other receptor mechanisms of goldfish. This examination revealed several striking functional differences: (1) The UV-sensitive cone mechanism threshold vs. background intensity (TVI) exhibited a slope of 0.65 (compared to the approximate 1.0 for the other cone mechanisms on a log/log plot) and thus was not in accordance with Weber's law. This may in part be related to the intrusion of the blue-sensitive mechanism at the upper radiance range. (2) The operation of the UV-sensitive cone mechanism was limited to intermediate intensities (i.e. not very dim or bright). (3) The UV-sensitive cone mechanism exhibited a Weber fraction or luminance contrast threshold of 0.316 that was approximately six times larger than the other cone mechanisms but comparable to the rod mechanism. This indicates that the UV-sensitive cone mechanism performs relatively poorly in terms of brightness contrast detection.
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Teliban, Alina, Fabian Bartsch, Marek Struck, Ralf Baron et Wilfrid Jänig. « Responses of intact and injured sural nerve fibers to cooling and menthol ». Journal of Neurophysiology 111, no 10 (15 mai 2014) : 2071–83. http://dx.doi.org/10.1152/jn.00287.2013.
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Intact and injured cutaneous C-fibers in the rat sural nerve are cold sensitive, heat sensitive, and/or mechanosensitive. Cold-sensitive fibers are either low-threshold type 1 cold sensitive or high-threshold type 2 cold sensitive. The hypothesis was tested, in intact and injured afferent nerve fibers, that low-threshold cold-sensitive afferent nerve fibers are activated by the transient receptor potential melastatin 8 (TRPM8) agonist menthol, whereas high-threshold cold-sensitive C-fibers and cold-insensitive afferent nerve fibers are menthol insensitive. In anesthetized rats, activity was recorded from afferent nerve fibers in strands isolated from the sural nerve, which was either intact or crushed 6–12 days before the experiment distal to the recording site. In all, 77 functionally identified afferent C-fibers (30 intact fibers, 47 injured fibers) and 34 functionally characterized A-fibers (11 intact fibers, 23 injured fibers) were tested for their responses to menthol applied to their receptive fields either in the skin (10 or 20%) or in the nerve (4 or 8 mM). Menthol activated all intact ( n = 12) and 90% of injured ( n = 20/22) type 1 cold-sensitive C-fibers; it activated no intact type 2 cold-sensitive C-fibers ( n = 7) and 1/11 injured type 2 cold-sensitive C-fibers. Neither intact nor injured heat- and/or mechanosensitive cold-insensitive C-fibers ( n = 25) and almost no A-fibers ( n = 2/34) were activated by menthol. These results strongly argue that cutaneous type 1 cold-sensitive afferent fibers are nonnociceptive cold fibers that use the TRPM8 transduction channel.
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Deng, Jufeng, Dian Song et Shijie Su. « Highly Sensitive Inertial Micro-Switch for Achieving Adjustable Multi-Threshold Acceleration ». Actuators 12, no 2 (26 janvier 2023) : 53. http://dx.doi.org/10.3390/act12020053.
Texte intégralRésumé :
An inertial micro-switch with multi-threshold acceleration detection capability has been proposed, taking advantage of electromechanical coupling behavior. A mathematical model of electromechanical coupling behavior was established to display the dependence of highly sensitivity on pull-in characteristic and show the ability to detect threshold acceleration by controlling the voltage applied to the inertial micro-switch. The capability of sensitivity and detection that was described in mathematical model was implemented to occur at the inertial switch and showed agreement with that of a simulation. Inertia switches that were comprised of various microstructures with dimensions ranging 3.5 µm from 180 µm were manufactured by means of the micro-electro-mechanical system (MEMS) manufacturing process, and their functions were evaluated by a dropping system. The control method related to the manufacturing of inertial switches was obtained by analyzing the effect of the structural parameters of the inertial switch on threshold voltage and threshold acceleration, resulting in a relatively small error between simulation and experiment. The inertial micro-switch showed high sensitivity to achieving the pull-in effect at 30 V, sense multi-threshold acceleration ranging from 500 g to 2000 g in 2.46 ms and provided enough time for outputting the acceleration signal. Furthermore, the multi-threshold acceleration can be adjusted by controlling the voltage applied to inertial micro-switches. In addition, other functions of inertial micro-switches, such as lower residual stress, high recoverability, and repeatability, have been displayed.
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Ogata, Nobukuni, et Hideharu Tatebayashi. « "Low-threshold TTX-sensitive" and "high-threshold TTX-insensitive" Na+ channels in rat dorsal root ganglia. » Japanese Journal of Pharmacology 55 (1991) : 282. http://dx.doi.org/10.1016/s0021-5198(19)39232-7.
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Prabdial-Sing, Nishi, Villyen Motaze, Jack Manamela, Kerrigan McCarthy et Melinda Suchard. « Establishment of Outbreak Thresholds for Hepatitis A in South Africa Using Laboratory Surveillance, 2017–2020 ». Viruses 13, no 12 (10 décembre 2021) : 2470. http://dx.doi.org/10.3390/v13122470.
Texte intégralRésumé :
As South Africa transitions from endemic to intermediate endemicity, hepatitis A surveillance needs strengthening to monitor trends in disease incidence and to identify outbreaks. We used passive laboratory-based surveillance data from the National Health Laboratory Services to calculate national hepatitis A incidence and to establish thresholds for outbreaks. Incidence was calculated by age and geographic location. The static threshold used two or three standard deviations (SDs) above the mean hepatitis A incidence in 2017–2019, and a cumulative summation (CuSum2) threshold used three SDs above the mean of the preceding seven months. These thresholds were applied to hepatitis A data for 2020. From 2017 to 2020, the mean incidence of hepatitis A IgM was 4.06/100,000 and ranged from 4.23 to 4.85/100,000 per year. Hepatitis A incidence was highest in the Western Cape province (WCP) (7.00–10.92/100,000 per year). The highest incidence was in the 1–9-year-olds. The incidence of hepatitis A in 2020 exceeded the static threshold in two districts of the WCP: Cape Winelands in January and Overberg district in August. The provincial incidence did not exceed the static and CuSum2 thresholds. District-level analysis using either threshold was sensitive enough to monitor trends and to alert district health authorities, allowing early outbreak responses.
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Huengsberg, Mia, John B. Winer, Jonathan DC Ross et Mohsen Shahmanesh. « Thermosensory threshold : a sensitive test of HIV associated peripheral neuropathy ? » Journal of Neurovirology 4, no 4 (janvier 1998) : 433–37. http://dx.doi.org/10.3109/13550289809114542.
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Verma, Surendra, et K. C. Mahajan. « USEP : Ultra Stable Threshold Sensitive Election Protocol for Mobile WSN ». International Journal of Computer Applications 100, no 3 (20 août 2014) : 5–8. http://dx.doi.org/10.5120/17503-8048.
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Fadaei Tehrani, Ahmad, et Faramarz Safi-Esfahani. « A threshold sensitive failure prediction method using support vector machine ». Multiagent and Grid Systems 13, no 2 (4 juillet 2017) : 97–111. http://dx.doi.org/10.3233/mgs-170263.
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J. Sánchez-Hermosilla et R. Medina. « ADAPTIVE THRESHOLD FOR DROPLET SPOT ANALYSIS USING WATER-SENSITIVE PAPER ». Applied Engineering in Agriculture 20, no 5 (2004) : 547–51. http://dx.doi.org/10.13031/2013.17454.
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Flyvholm, Mari-Ann, Barbara M. Hall, Tove Agner, Eva Tiedemann, Peter Greenhill, Walter Vanderveken, Fred E. Freeberg et Torkil Menné. « Threshold for occluded formaldehyde patch test in formaldehyde-sensitive patients ». Contact Dermatitis 36, no 1 (janvier 1997) : 26–33. http://dx.doi.org/10.1111/j.1600-0536.1997.tb00918.x.
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Wallace, K. J., Bruce D. Clarkson et Bridgette Farnworth. « Restoration Trajectories and Ecological Thresholds during Planted Urban Forest Successional Development ». Forests 13, no 2 (27 janvier 2022) : 199. http://dx.doi.org/10.3390/f13020199.
Texte intégralRésumé :
Successfully reconstructing functioning forest ecosystems from early-successional tree plantings is a long-term process that often lacks monitoring. Many projects lack observations of critical successional information, such as the restoration trajectory of key ecosystem attributes and ecological thresholds, which signal that management actions are needed. Here, we present results from a 65 ha urban temperate rainforest restoration project in Aotearoa New Zealand, where trees have been planted annually on public retired pasture land, forming a 14 years chronosequence. In 25 plots (100 m2 each), we measured key ecosystem attributes that typically change during forest succession: native tree basal area, canopy openness, non-native herbaceous ground cover, leaf litter cover, ground fern cover, dead trees, and native tree seedling abundance and richness. We also monitored for the appearance of physiologically-sensitive plant guilds (moss, ferns, and epiphytes) that may be considered ecological indicators of succession. Linear regression models identified relationships between all but one of the key ecosystem attributes and forest age (years since planting). Further, using breakpoint analysis, we found that ecological thresholds occurred in many ecosystem attributes during their restoration trajectories: reduced canopy openness (99.8% to 3.4%; 9.6 years threshold), non-native herbaceous ground cover (100% to 0; 10.9 years threshold), leaf litter cover (0 to 95%; 10.8 years threshold), and increased tree deaths (0 to 4; 11 years threshold). Further, juvenile native plant recruitment increased (tree seedling abundance 0 to ~150 per 4 m2), tree seedling species richness (0 to 13 per 100 m2) and epiphytes colonized (0 to 3 individuals per 100 m2). These and other physiologically-sensitive plant guilds appeared around the 11 years mark, confirming their utility as ecological indicators during monitoring. Our results indicate that measurable, ecological thresholds occur during the restoration trajectories of ecosystem attributes, and they are predictable. If detected, these thresholds can inform project timelines and, along with use of ecological indicators, inform management interventions.
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Burgoon, Penny W., et Jack A. Boulant. « Temperature-sensitive properties of rat suprachiasmatic nucleus neurons ». American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 281, no 3 (1 septembre 2001) : R706—R715. http://dx.doi.org/10.1152/ajpregu.2001.281.3.r706.
Texte intégralRésumé :
The hypothalamic suprachiasmatic nucleus (SCN) contains a heterogeneous population of neurons, some of which are temperature sensitive in their firing rate activity. Neuronal thermosensitivity may provide cues that synchronize the circadian clock. In addition, through synaptic inhibition on nearby cells, thermosensitive neurons may provide temperature compensation to other SCN neurons, enabling postsynaptic neurons to maintain a constant firing rate despite changes in temperature. To identify mechanisms of neuronal thermosensitivity, whole cell patch recordings monitored resting and transient potentials of SCN neurons in rat hypothalamic tissue slices during changes in temperature. Firing rate temperature sensitivity is not due to thermally dependent changes in the resting membrane potential, action potential threshold, or amplitude of the fast afterhyperpolarizing potential (AHP). The primary mechanism of neuronal thermosensitivity resides in the depolarizing prepotential, which is the slow depolarization that occurs prior to the membrane potential reaching threshold. In thermosensitive neurons, warming increases the prepotential's rate of depolarization, such that threshold is reached sooner. This shortens the interspike interval and increases the firing rate. In some SCN neurons, the slow component of the AHP provides an additional mechanism for thermosensitivity. In these neurons, warming causes the slow AHP to begin at a more depolarized level, and this, in turn, shortens the interspike interval to increase firing rate.
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Werner, Lynne A., Richard C. Folsom, Lisa R. Mancl et Connie L. Syapin. « Human Auditory Brainstem Response to Temporal Gaps in Noise ». Journal of Speech, Language, and Hearing Research 44, no 4 (août 2001) : 737–50. http://dx.doi.org/10.1044/1092-4388(2001/058).
Texte intégralRésumé :
Gap detection is a commonly used measure of temporal resolution, although the mechanisms underlying gap detection are not well understood. To the extent that gap detection depends on processes within, or peripheral to, the auditory brainstem, one would predict that a measure of gap threshold based on the auditory brainstem response (ABR) would be similar to the psychophysical gap detection threshold. Three experiments were performed to examine the relationship between ABR gap threshold and gap detection. Thresholds for gaps in a broadband noise were measured in young adults with normal hearing, using both psychophysical techniques and electrophysiological techniques that use the ABR. The mean gap thresholds obtained with the two methods were very similar, although ABR gap thresholds tended to be lower than psychophysical gap thresholds. There was a modest correlation between psychophysical and ABR gap thresholds across participants. ABR and psychophysical thresholds for noise masked by temporally continuous, high-pass, or spectrally notched noise were measured in adults with normal hearing. Restricting the frequency range with masking led to poorer gap thresholds on both measures. High-pass maskers affected the ABR and psychophysical gap thresholds similarly. Notched-noise-masked ABR and psychophysical gap thresholds were very similar except that low-frequency, notched-noise-masked ABR gap threshold was much poorer at low levels. The ABR gap threshold was more sensitive to changes in signal-to-masker ratio than was the psychophysical gap detection threshold. ABR and psychophysical thresholds for gaps in broadband noise were measured in listeners with sensorineural hearing loss and in infants. On average, both ABR gap thresholds and psychophysical gap detection thresholds of listeners with hearing loss were worse than those of listeners with normal hearing, although individual differences were observed. Psychophysical gap detection thresholds of 3- and 6-month-old infants were an order of magnitude worse than those of adults with normal hearing, as previously reported; however, ABR gap thresholds of 3-month-old infants were no different from those of adults with normal hearing. These results suggest that ABR gap thresholds and psychophysical gap detection depend on at least some of the same mechanisms within the auditory system.
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Kyhn, Line A., Jakob Tougaard, Jonas Teilmann, Magnus Wahlberg, Poul B. Jørgensen et Nikolaj I. Bech. « Harbour porpoise (Phocoena phocoena) static acoustic monitoring : laboratory detection thresholds of T-PODs are reflected in field sensitivity ». Journal of the Marine Biological Association of the United Kingdom 88, no 6 (17 mars 2008) : 1085–91. http://dx.doi.org/10.1017/s0025315408000416.
Texte intégralRésumé :
The T-POD (Timing POrpoise Detector) is a self-contained acoustic data logger used for detecting and monitoring the presence of echolocation clicks of small cetaceans. It has become a standard tool in environmental impact assessments and monitoring programmes. Yet, little is known about the variability in sensitivity and detection range of T-PODs. In this study the field performance of ten v3 T-PODs was compared to detection thresholds measured in a tank. The T-POD thresholds ranged from 123 to 132 dB re 1μPa (pp). The detection thresholds of the ten individual T-PODs were different and the differences increased over time. The more sensitive a T-POD was in the laboratory (i.e. the lower the threshold) the more clicks were recorded by it in the field. Threshold correlated differently to the five analysed T-POD parameters (encounters, encounter duration, waiting time, porpoise positive minutes, clicks per porpoise positive minute). This study demonstrates that individual threshold calibrations of T-PODs are necessary to obtain comparable results when monitoring odontocetes with this tool. Regression equations for relationships between T-POD detection thresholds and study parameters obtained during field trials may allow comparisons of T-PODs with different detection thresholds.
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Kamada, Chie, Rei Enatsu, Aya Kanno, Satoko Ochi, Shoto Yamada, Ryota Sato, Ryohei Chiba et Nobuhiro Mikuni. « Intraoperative nerve stimulation during vagal nerve stimulator placement ». Surgical Neurology International 14 (1 septembre 2023) : 312. http://dx.doi.org/10.25259/sni_303_2023.
Texte intégralRésumé :
Background: Vagal nerve stimulation (VNS) is a palliative treatment for refractory epilepsy and intraoperative nerve stimulation is applied to the vagal and other nerves to prevent electrode misplacement. We evaluated these thresholds to establish intraoperative monitoring procedures for VNS surgery. Methods: Forty-six patients who underwent intraoperative nerve stimulation during VNS placement were enrolled. The vagal nerve and other exposed nerves were electrically stimulated during surgery, and muscle contraction was confirmed by electromyography of the vocal cords and visual recognition of cervical muscle contraction. The nerve thresholds and the most sensitive parts of the vagal nerve were analyzed retrospectively. Results: The stimulation of vagal nerves induced vocal cord responses in all 46 patients; the median thresholds of the most sensitive parts and all parts were 0.2 mA (range: 0.05–0.75 mA) and 0.25 mA (range: 0.15–1.5 mA), respectively. The medial middle region was identified as the most sensitive part of the vagal nerve in the majority of participants (82.5%). In 11 patients, other cervical nerves were stimulated and sternohyoid muscle contraction was induced with a median threshold of 0.35 mA (range: 0.1–0.7 mA) in eight patients, while sternocleidomastoid muscle contraction was induced with a median threshold of 0.2 mA (range: 0.1–0.2 mA) in three. Conclusion: Intraoperative stimulation of vagal nerves induces vocal cord responses with locational variations, and the middle part stimulation could minimize the stimulus intensities. The nerves innervating the sternohyoid and sternocleidomastoid muscles may be exposed during the procedure. Knowledge of these characteristics will enhance the effectiveness of this technique in future applications.
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Sharma, K., P. Sharma, A. Sharma et G. Singh. « Phenylthiocarbamide taste perception and susceptibility to motion sickness : linking higher susceptibility with higher phenylthiocarbamide taste acuity ». Journal of Laryngology & ; Otology 122, no 10 (5 février 2008) : 1064–73. http://dx.doi.org/10.1017/s0022215107001442.
Texte intégralRésumé :
AbstractObjective:This study is the first attempt to link quantified phenylthiocarbamide bitter taste recognition threshold with susceptibility to motion sickness.Subjects:The study was conducted on a sample of 291 teenage Rajput children (146 males and 145 females; age range 13–19 years) from the Sirmour district of Himachal Pradesh, India. Phenylthiocarbamide taste sensitivity was measured by administering a serial dilution of a freshly prepared phenylthiocarbamide solution, following the method of Harris and Kalmus. Motion sickness susceptibility was assessed retrospectively via interview.Results:About 40 per cent of the subjects had experienced motion sickness in the past. The mean and standard deviation of phenylthiocarbamide taste thresholds in non-tasters and tasters were 0.83 ± 0.87 and 7.98 ± 1.86, respectively. A bimodal distribution test (D/S) index of 5.24 confirmed bimodality of phenylthiocarbamide taste threshold distribution. The Mann–Whitney U test rejected the null hypothesis of μ1 = μ2 and thus confirmed the existence of differences in the distributions of phenylthiocarbamide taste threshold between individuals susceptible and not susceptible to motion sickness. Individuals susceptible to motion sickness had lower mean and median taste thresholds, indicating higher phenylthiocarbamide taste sensitivity, compared with non-susceptible individuals. The frequency of non-tasters was about 10 per cent in both motion sickness susceptible and non-susceptible individuals. The simple division of phenylthiocarbamide tasting ability into tasters and non-tasters was a less sensitive criterion with which to measure the association of this ability with motion sickness susceptibility. However, further differentiation of tasters into weak threshold, medium threshold and super threshold (‘supersensitive’) tasters clearly revealed a highly significantly increased risk of motion sickness in super threshold tasters (i.e. threshold solution number ≥12). The ratio of motion sickness susceptible individuals to non-susceptible individuals was 1:1.7 for non-tasters (threshold solution numbers zero to three) and weak and medium tasters (threshold solution numbers four to 11), but the trend was reversed for super threshold tasters (threshold solution numbers 12 and 13), in whom the ratio was 2:1.Conclusion:Individuals exhibiting greater phenylthiocarbamide taste acuity (i.e. supersensitive tasters) had a higher susceptibility to motion sickness than did non-, weak and medium phenylthiocarbamide tasters, as measured in terms of their taste thresholds (i.e. threshold solution numbers zero to 11).
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Feeney, M. Patrick, Douglas H. Keefe et Lindsay P. Marryott. « Contralateral Acoustic Reflex Thresholds for Tonal Activators Using Wideband Energy Reflectance and Admittance ». Journal of Speech, Language, and Hearing Research 46, no 1 (février 2003) : 128–36. http://dx.doi.org/10.1044/1092-4388(2003/010).
Texte intégralRésumé :
The purpose of this study was to evaluate a new method for estimating the acoustic reflex threshold incorporating wideband (250–8000 Hz) measures of energy reflectance and admittance (M. P. Feeney & D. H. Keefe, 2001). The wideband technique incorporates both a correlation method to assess the pattern of the reflex-induced shifts in reflectance and admittance across frequency and a magnitude method to determine if the amplitude of the shifts exceeds baseline variability. Contralateral reflex thresholds for 1000- and 2000-Hz activators were obtained for 34 young adults with both the wideband method and a clinical method using a 226 Hz probe tone. Average reflex thresholds obtained with the new method were 12 to 13.7 dB lower than those obtained with the clinical method. When the bandwidth of analysis of admittance and reflectance responses was limited to 250 to 2000 Hz, the reduction in reflex thresholds was accompanied by the rejection of 96% of nonactivator-baseline responses as reflexes. The method holds promise for extending reflex threshold testing to patients with reflexes elevated beyond current equipment limits, for reducing the sound levels used in reflex testing, and for obtaining sensitive measures of reflex threshold in infants.
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Melchiorre, C., et A. Tryggvason. « Application of a fast and efficient algorithm to assess landslide-prone areas in sensitive clays in Sweden ». Natural Hazards and Earth System Sciences 15, no 12 (21 décembre 2015) : 2703–13. http://dx.doi.org/10.5194/nhess-15-2703-2015.
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Abstract. We refine and test an algorithm for landslide susceptibility assessment in areas with sensitive clays. The algorithm uses soil data and digital elevation models to identify areas which may be prone to landslides and has been applied in Sweden for several years. The algorithm is very computationally efficient and includes an intelligent filtering procedure for identifying and removing small-scale artifacts in the hazard maps produced. Where information on bedrock depth is available, this can be included in the analysis, as can information on several soil-type-based cross-sectional angle thresholds for slip. We evaluate how processing choices such as of filtering parameters, local cross-sectional angle thresholds, and inclusion of bedrock depth information affect model performance. The specific cross-sectional angle thresholds used were derived by analyzing the relationship between landslide scarps and the quick-clay susceptibility index (QCSI). We tested the algorithm in the Göta River valley. Several different verification measures were used to compare results with observed landslides and thereby identify the optimal algorithm parameters. Our results show that even though a relationship between the cross-sectional angle threshold and the QCSI could be established, no significant improvement of the overall modeling performance could be achieved by using these geographically specific, soil-based thresholds. Our results indicate that lowering the cross-sectional angle threshold from 1 : 10 (the general value used in Sweden) to 1 : 13 improves results slightly. We also show that an application of the automatic filtering procedure that removes areas initially classified as prone to landslides not only removes artifacts and makes the maps visually more appealing, but it also improves the model performance.
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Chen, Wenguo, Rui Wang, Huiying Wang et Zhen Yang. « Design, Simulation, and Fabrication of a New Three-Axis Inertial Switch with a Triangular Movable Electrode Structure ». Micromachines 14, no 1 (30 décembre 2022) : 94. http://dx.doi.org/10.3390/mi14010094.
Texte intégralRésumé :
A new three-axis inertial switch is proposed. The triangle-structured movable electrode is designed to improve the inertial switch’s dynamic response performance, especially the movable electrode’s dynamic stability performance. The static mechanical analysis indicated that the displacement of the movable electrode to the fixed electrode in the sensitive direction is the minimum when the acceleration is applied to this designed inertial switch. The dynamic simulation analysis showed that the threshold of the designed inertial is about 235 g. The threshold in the non-sensitive direction is about 240 g, 270 g, 300 g, and 350 g when the directions of applied acceleration deviate 15°, 30°, 45°, and 60° from the sensitive direction, respectively. These results indicated that the designed inertial could resist the impact in non-sensitive directions and improve the stability in sensitive directions. The prototype of the inertial switch was fabricated and tested successfully. The testing results indicate that the threshold of the fabricated inertial switch is about 219 g. The test results verify the dynamic stability performance of the designed inertial switch.
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Zhang, Ning, Lin Sun, Zhendong Sun et Yu Qu. « Detecting Low-Intensity Fires in East Asia Using VIIRS Data : An Improved Contextual Algorithm ». Remote Sensing 13, no 21 (21 octobre 2021) : 4226. http://dx.doi.org/10.3390/rs13214226.
Texte intégralRésumé :
The Visible Infrared Imaging Radiometer Suite (VIIRS) fire detection algorithm mostly relies on thermal infrared channels that possess fixed or context-sensitive thresholds. The main channel used for fire identification is the mid-infrared channel, which has relatively low temperature saturation. Therefore, when the high temperature of a fire in this channel is used for initial screening, the threshold is relatively high. Although screening results are tested at different levels, few small fires will be lost under these strict test conditions. However, crop burning fires often occur in East Asia at a small scale and relatively low temperature, such that their radiative characteristics cannot meet the global threshold. Here, we propose a new weighted fire test algorithm to accurately detect small-scale fires based on differences in the sensitivity of test conditions to fire. This method reduces the problem of small fires being ignored because they do not meet some test conditions. Moreover, the adaptive threshold suitable for small fires is selected by bubble sorting according to the radiation characteristics of small fires. Our results indicate that the improved algorithm is more sensitive to small fires, with accuracies of 53.85% in summer and 73.53% in winter, representing an 18.69% increase in accuracy and a 28.91% decline in error rate.
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Butler, Matthew P., et Rae Silver. « Divergent photic thresholds in the non-image-forming visual system : entrainment, masking and pupillary light reflex ». Proceedings of the Royal Society B : Biological Sciences 278, no 1706 (22 septembre 2010) : 745–50. http://dx.doi.org/10.1098/rspb.2010.1509.
Texte intégralRésumé :
Light is the principal cue that entrains the circadian timing system, but the threshold of entrainment and the relative contributions of the retinal photoreceptors—rods, cones and intrinsically photosensitive retinal ganglion cells—are not known. We measured thresholds of entrainment of wheel-running rhythms at three wavelengths, and compared these to thresholds of two other non-image-forming visual system functions: masking and the pupillary light reflex (PLR). At the entrainment threshold, the relative spectral sensitivity and absolute photon flux suggest that this threshold is determined by rods. Dim light that entrained mice failed to elicit either masking or PLR; in general, circadian entrainment is more sensitive by 1–2 log units than other measures of the non-image-forming visual system. Importantly, the results indicate that dim light can entrain circadian rhythms even when it fails to produce more easily measurable acute responses to light such as phase shifting and melatonin suppression. Photosensitivity to one response, therefore, cannot be generalized to other non-image-forming functions. These results also impact practical problems in selecting appropriate lighting in laboratory animal husbandry.
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Mittal, Mamta, Rajendra Kumar Sharma, Varinder Pal Singh et Raghvendra Kumar. « Adaptive Threshold Based Clustering ». International Journal of Information System Modeling and Design 10, no 1 (janvier 2019) : 42–59. http://dx.doi.org/10.4018/ijismd.2019010103.
Texte intégralRésumé :
Partitioning-based clustering methods have various challenges especially user-defined parameters and sensitivity to initial seed selections. K-means is most popular partitioning based method while it is sensitive to outlier, generate non-overlap cluster and non-deterministic in nature due to its sensitivity to initial seed selection. These limitations are regarded as promising research directions. In this study, a deterministic approach which do not requires user defined parameters during clustering; can generate overlapped and non-overlapped clusters and detect outliers has been proposed. Here, a minimum support value has been adopted from association rule mining to improve the clustering results. Further, the improved approach has been analysed on artificial and real datasets. The results demonstrated that datasets are well clustered with this approach too and it achieved success to generate almost same number of clusters as present in real datasets.
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Lindberg, Herbert E. « Dynamic Pulse Buckling of Imperfection-Sensitive Shells ». Journal of Applied Mechanics 58, no 3 (1 septembre 1991) : 743–48. http://dx.doi.org/10.1115/1.2897258.
Texte intégralRésumé :
The theoretical basis of two related but distinctly different dynamic buckling criteria are summarized with the objective of demonstrating the range of applicability of each, so that together they cover the entire range of dynamic pulse loads from nearly impulsive loads to step loads of infinite duration. The example chosen is a cylindrical shell under elastic axial loads but the approach is applicable more generally. A critical amplification-of-imperfections criterion with a linear shell theory is shown to be applicable for short duration loads, for which a threshold nonlinear divergence criterion gives loads an order of magnitude too conservative. Conversely, the linear theory is inapplicable for long duration loads, for which critical loads are lower than the linear static buckling load because of imperfection sensitivity. In this range the threshold nonlinear divergence criterion is used. For loads of intermediate duration, an extended critical amplification criterion is used with equations that conservatively assume zero static buckling load but give an unchanged formula for critical load amplitude-duration combinations.
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Gold, Joshua I., Chi-Tat Law, Patrick Connolly et Sharath Bennur. « Relationships Between the Threshold and Slope of Psychometric and Neurometric Functions During Perceptual Learning : Implications for Neuronal Pooling ». Journal of Neurophysiology 103, no 1 (janvier 2010) : 140–54. http://dx.doi.org/10.1152/jn.00744.2009.
Texte intégralRésumé :
Perceptual learning involves long-lasting improvements in the ability to perceive simple sensory stimuli. Some forms of perceptual learning are thought to involve an increasingly selective readout of sensory neurons that are most sensitive to the trained stimulus. Here we report novel changes in the relationship between the threshold and slope of the psychometric function during learning that are consistent with such changes in readout and can provide insights into the underlying neural mechanisms. In monkeys trained on a direction-discrimination task, perceptual improvements corresponded to lower psychometric thresholds and slightly shallower slopes. However, this relationship between threshold and slope was much weaker in comparable, ideal-observer “neurometric” functions of neurons in the middle temporal (MT) area, which represent sensory information used to perform the task and whose response properties did not change with training. We propose a linear/nonlinear pooling scheme to account for these results. According to this scheme, MT responses are pooled via linear weights that change with training to more selectively read out responses from the most sensitive neurons, thereby reducing predicted thresholds. An additional nonlinear (power-law) transformation does not change with training and causes the predicted psychometric function to become shallower as uninformative neurons are eliminated from the pooled signal. We show that this scheme is consistent with the measured changes in psychometric threshold and slope throughout training. The results suggest that some forms of perceptual learning involve improvements in a process akin to selective attention that pools the most informative neural signals to guide behavior.
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Rachmilewitz, Jacob, Gregory J. Riely, Jui-Han Huang, Aoshuang Chen et Mark L. Tykocinski. « A rheostatic mechanism for T-cell inhibition based on elevation of activation thresholds ». Blood 98, no 13 (15 décembre 2001) : 3727–32. http://dx.doi.org/10.1182/blood.v98.13.3727.
Texte intégralRésumé :
Abstract The activation of discrete T-cell responses depends on the triggering of individualized threshold numbers of T-cell receptors (TCRs). The results of this study indicate that the lipocalin placental protein 14 (PP14), a T-cell inhibitor produced by cells of the reproductive and hematopoietic systems, mediates its anti-inflammatory activity by elevating the T-cell activation threshold, thereby rendering T cells less sensitive to stimulation. Significantly, the data demonstrate hierarchical sensitivity of selected cytokine responses to PP14-mediated inhibition, with the hierarchy reflecting their respective activation thresholds. These findings suggest a novel paradigm for immunoinhibition wherein negative regulators can finely tune, rather than inactivate, T-cell responses, and thereby skew the cytokine output of immunologic responses.
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Chen, Yue, Harold E. Bedell et Laura J. Frishman. « Temporal-Contrast Discrimination and its Neural Correlates ». Perception 25, no 5 (mai 1996) : 505–22. http://dx.doi.org/10.1068/p250505.
Texte intégralRésumé :
Reported differences in neuronal contrast processing between the parallel magnocellular (M) and parvocellular (P) visual pathways invite the hypothesis that contrast discrimination in the human visual system is more sensitive at low contrasts and less sensitive at high contrasts, for stimuli modulated at high compared with low temporal frequencies. In the present study, an edgeless temporally modulated uniform field was selected as the stimulus for psychophysical contrast discrimination, and contrast-increment thresholds for pedestal contrasts ranging from 5.5% to 78.2% were determined with a temporal two-alternative forced-choice staircase procedure. The increment thresholds for five normal subjects were adequately fit by power functions with exponents that shifted continuously from about 0.5 (square-root-law behavior) to about 1.0 (Weber's-law behavior) as stimulus temporal frequency increased from 1 to 30 Hz. A neural simulation, with the use of published contrast-response functions of magnocellular and parvocellular neurons, adjusted with an estimate of response variance, produced two distinct ‘neural increment-threshold functions’ that were similar to the psychophysical results obtained at the highest and the lowest temporal frequencies, respectively. A shift from a relatively more noise-limited neural mechanism to one whose response is predominantly determined by gain is suggested to account for the change of the contrast-increment-threshold function with increasing temporal frequency.
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Le Prell, Colleen G., Christopher Spankovich, Edward Lobariñas et Scott K. Griffiths. « Extended High-Frequency Thresholds in College Students : Effects of Music Player Use and Other Recreational Noise ». Journal of the American Academy of Audiology 24, no 08 (septembre 2013) : 725–39. http://dx.doi.org/10.3766/jaaa.24.8.9.
Texte intégralRésumé :
Background: Human hearing is sensitive to sounds from as low as 20 Hz to as high as 20,000 Hz in normal ears. However, clinical tests of human hearing rarely include extended high-frequency (EHF) threshold assessments, at frequencies extending beyond 8000 Hz. EHF thresholds have been suggested for use monitoring the earliest effects of noise on the inner ear, although the clinical usefulness of EHF threshold testing is not well established for this purpose. Purpose: The primary objective of this study was to determine if EHF thresholds in healthy, young adult college students vary as a function of recreational noise exposure. Research Design: A retrospective analysis of a laboratory database was conducted; all participants with both EHF threshold testing and noise history data were included. The potential for “preclinical” EHF deficits was assessed based on the measured thresholds, with the noise surveys used to estimate recreational noise exposure. Study Sample: EHF thresholds measured during participation in other ongoing studies were available from 87 participants (34 male and 53 female); all participants had hearing within normal clinical limits (≤25 HL) at conventional frequencies (0.25–8 kHz). Results: EHF thresholds closely matched standard reference thresholds [ANSI S3.6 (1996) Annex C]. There were statistically reliable threshold differences in participants who used music players, with 3–6 dB worse thresholds at the highest test frequencies (10–16 kHz) in participants who reported long-term use of music player devices (>5 yr), or higher listening levels during music player use. Conclusions: It should be possible to detect small changes in high-frequency hearing for patients or participants who undergo repeated testing at periodic intervals. However, the increased population-level variability in thresholds at the highest frequencies will make it difficult to identify the presence of small but potentially important deficits in otherwise normal-hearing individuals who do not have previously established baseline data.
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Zhao, Liquan, et Qi Tang. « An Improved Threshold-Sensitive Stable Election Routing Energy Protocol for Heterogeneous Wireless Sensor Networks ». Information 10, no 4 (5 avril 2019) : 125. http://dx.doi.org/10.3390/info10040125.
Texte intégralRésumé :
In the Threshold-Sensitive Stable Election Protocol, sensors are randomly deployed in the region without considering the balanced energy consumption of nodes. If a node that has been selected as a cluster head is located far away from the base station, it will affect the efficiency of the network due to its early death. This paper proposes an improved energy efficient routing protocol named Improved Threshold-Sensitive Stable Election protocol (ITSEP) for heterogeneous wireless sensor networks. Firstly, we use a node state transformation mechanism to control the number of cluster heads in high-density node areas. Secondly, the proposed protocol improves the threshold formula by considering the distance from the node to the base station, the number of neighbor nodes, its residual energy, and the average distance between nodes. In addition, an optimal route with minimum energy consumption for cluster heads has been selected throughout data transmission. Simulation results show that this algorithm has achieved a longer lifetime than the stable election protocol algorithm, modified stable election protocol algorithm, and threshold-sensitive stable election protocol algorithm for the heterogeneous wireless sensor network.