Papers by Kenneth B Chiacchia
The Journal of Search and Rescue, Aug 31, 2023
The Journal of Search and Rescue, Jan 30, 2023
Effective sweep width (W) promises objective probability of detection (POD) values for guiding mi... more Effective sweep width (W) promises objective probability of detection (POD) values for guiding missingperson search efforts. However, methods for measuring W produce large uncertainties. Also, models for generating POD from W have not been validated for ground-based search. The authors applied leastsquare fits of POD data collected in the field for air-scent dog teams as well as human searchers using the two most prevalent models to derive W values. The method routinely fits the data to an R-square of >.8 with more statistical power than previous methods, and appears to be detector-agnostic. The authors present recommendations for optimizing its use in the field.
Wilderness & Environmental Medicine, 2015
Objective.-We sought to obtain the first effective sweep widths (ESWs) ever measured for an airsc... more Objective.-We sought to obtain the first effective sweep widths (ESWs) ever measured for an airscent search dog unit to compare their performance to historical data from human searchers and to initially test the validity of atmospheric convection as a limiting factor in air-scent search. Methods.-We used GPS tracks and waypoints to measure lateral hit and miss distances for the dog teams during blinded, randomized training tasks during a 6-year period, calculating ESW using the crossover method. During the tasks we collected weather data for determining convection. We used nonparametric statistics and least-square regression to compare the dog ESW data with historical human data and weather conditions. Results.-The mean value of ESW for the 4 teams under all conditions was 95 m (95% CI, 44 to 145). The dog teams' performance was statistically superior to human visual searchers in detecting search subjects in low-visibility colors, but not subjects in high-visibility colors. A nonparametric correlation test of ESW vs convection gave P o .05, suggesting that convection may be an operationally significant factor in air-scent dog performance. Conclusions.-The ESW methodology is applicable to air-scent dog teams, potentially allowing search managers to make decisions in applying resources operationally, as well as improving accuracy of planning calculations. In addition, the methods described appear to be capable, given more widely representative data, of making valid statistical comparisons between different search modalities and weather and other factors.
Wilderness & Environmental Medicine, 2010
Background.-Although lost-person search managers try to direct search efforts quantitatively, it ... more Background.-Although lost-person search managers try to direct search efforts quantitatively, it has historically been difficult to quantify the efficacy of search efforts accurately. The effective-sweepwidth (ESW) methodology represents an avenue for accomplishing this goal but has not yet been widely disseminated among practitioners. Methods.-We obtained ESW values in the summer and winter in a typical disturbed-forest environment in southwest Pennsylvania. We used nonparametric statistics to compare individual ESW values for two types of search objects detected by 18 summer and 20 winter searchers, cumulating the P values for similar comparisons and correcting for false discovery via a stepped method. Results.-We detected robust differences (all at P Ͻ.001) associated with search object color, season, and vegetation thickness. In contrast with earlier studies, we found a significant correlation between individual searchers' ESWs for different search objects and different types of vegetation (P Ͻ.001). We also found that adolescent searchers had significantly lower ESW values than adults (P ϭ .002). Apparently significant positive correlations between time spent on the course or field search experience and ESW disappeared when teens were excluded from the comparisons. Conclusions.-These results (the first comparison of seasonal ESW effects in identical terrain) represent the first statistical demonstration that the ESW methodology provides more than enough resolution to answer fundamental questions about the efficacy of visual search for lost persons by human searchers. They also add support to the imperative of operationally disseminating these methods among search-and-rescue practitioners, and offer some initial operational lessons for search managers.
Wilderness & Environmental Medicine, 2014
Objective.-Standard-of-practice search management requires that the probability of detection (POD... more Objective.-Standard-of-practice search management requires that the probability of detection (POD) be determined for each search resource after a task. To calculate the POD, a detection index (W) is obtained by field experiments. Because of the complexities of the land environment, search planners need a way to estimate the value of W without conducting formal experiments. We demonstrate a robust empirical correlation between detection range (Rd) and W, and argue that Rd may reliably be used as a quick field estimate for W. Methods.-We obtained the average maximum detection range (AMDR), Rd, and W values from 10 detection experiments conducted throughout North America. We measured the correlation between Rd and W, and tested whether the apparent relationship between W and Rd was statistically significant. Results.-On average we found W E 1.645 Â Rd with a strong correlation (R 2 ¼ .827). The highvisibility class had W E 1.773 Â Rd (also R 2 ¼ .867), the medium-visibility class had W E 1.556 Â Rd (R 2 ¼ .560), and the low-visibility had a correction factor of 1.135 (R 2 ¼ .319) for Rd to W. Using analysis of variance and post hoc testing, only the high-and low-visibility classes were significantly different from each other (P o .01). We also found a high correlation between the AMDR and Rd (R 2 ¼ .9974). Conclusions.-Although additional experiments are required for the medium-and low-visibility search objects and in the dry-domain ecoregion, we suggest search planners use the following correction factors to convert field-measured Rd to an estimate of the effective sweep width (W): highvisibility W ¼ 1.8 Â Rd; medium-visibility W ¼ 1.6 Â Rd; and low-visibility W ¼ 1.1 Â Rd.
Wilderness & Environmental Medicine
Introductiond"Critical separation" is a simple method for spacing searchers intended to produce a... more Introductiond"Critical separation" is a simple method for spacing searchers intended to produce a predictable probability of detection (POD). A more precise method, based on effective sweep width (W), has been adopted only slowly. Accurate PODs are critical in planning priorities in future operational periods. Therefore, it would be useful to know what POD a critical separation determination actually produces. MethodsdDetection ranges (Rd) were measured on high-and low-visibility adult mannequins (stuffed Tyvek suits of varying colors) and a red helmet detected by 6 searcher volunteers. Conversion factors previously described in the literature were used to convert Rds into predicted Ws and the previously described logit model to convert Ws into PODs. ResultsdThe Rds were 26±6 m (mean±SD) for the high-visibility mannequin, 15±5 m for the low-visibility mannequin, and 24±6 m for the helmet used in the critical separation determination. The predicted Ws were 47±15 m, 16±8 m, and 42±14 m, respectively. Critical separation would therefore result in predicted PODs of 67±17% or 32±16% for nonresponsive adults in high-versus low-visibility clothing. ConclusionsdCritical separation is a simple, quick way to array searchers in the field. The current study suggests that the value of critical separation in producing the 50% target POD will depend on the whether the search object used for the critical separation determination has a similar detectability/W to the actual target of the search effort. Still, the results from a critical separation determination may offer more predictability and reliability than the common practice of POD estimation by team leaders.
Reoxidation of the class I disulfides of the rat adipocyte insulin receptor is dependent upon the presence of insulin: the class I disulfide of the insulin receptor is extracellular
Biochemistry, 1988
Elements of the quaternary structure of the native and dithiothreitol- (DTT) reduced rat adipocyt... more Elements of the quaternary structure of the native and dithiothreitol- (DTT) reduced rat adipocyte insulin receptor have been elucidated by vectorial probing and subunit cross-linking. The charged reducing agents glutathione and beta-mercaptoethylamine were used to reduce the class I disulfides of the receptor in intact adipocytes, demonstrating the extracellular location of the disulfide directly. This interpretation was confirmed by use of DTT as a reducing agent and the nonpermeant sulfhydryl blocking reagent Thiolyte MQ to prevent the reoxidation of the class I sulfhydryl groups which occurred when they were not blocked. It was found that the above reoxidation of the receptor is dependent on the concentration of insulin in the nanomolar range, not occurring measurably at 4 degrees C in its absence. Cross-linking studies with ethylene glycol bis(succinimidyl succinate) demonstrated that the alpha subunits could not be cross-linked to each other after reduction of the class I disulfides, suggesting that the interaction between the receptor heterodimers may be due primarily to the disulfide bonds.
The Journal of biological chemistry, Jan 25, 1984
The technique of vectorial labeling has been used to study the orientation of the rat and chicken... more The technique of vectorial labeling has been used to study the orientation of the rat and chicken receptors for asialo- and agalactoglycoproteins in hepatocyte membranes. The membrane-impermeant enzyme lactoperoxidase was used to radioiodinate the outer surfaces of intact cells and endocytic vesicles, as well as both sides of total microsomal membranes. Proteolytically and chemically produced fragments of the receptor polypeptides were analyzed to identify the tyrosine residues modified in each case. The results reveal that each of these receptors is a transmembrane glycoprotein arranged with its NH2 terminus facing the cytoplasm and its COOH terminus, containing the carbohydrate-binding site, exposed at the cell surface. While the primary structures of the chicken and rat receptors are highly homologous in the extracellular portions of the proteins, the cytoplasmic domains show no sequence similarity.
Quantitation of the class I disulfides of the insulin receptor
Biochemical and Biophysical Research Communications, 1991
ABSTRACT The disulfide structure of the insulin receptor was probed using dithiothreitol and [3H]... more ABSTRACT The disulfide structure of the insulin receptor was probed using dithiothreitol and [3H]-N-ethylmaleimide to reduce purified human placental receptor and label the cysteine residues. After protein quantitation, the amount of radioactivity in both the alpha and beta subunits was counted for each of the three species generated: native dimer, reduced receptor which remained covalently dimeric, and reduced monomer. It was found that the native receptor contained only one sulfhydryl group, on the beta subunit; the reduced dimer contained one new sulfhydryl on each alpha subunit, and the alpha subunit of the monomer contained two sulfhydryls. This suggests a simple model for the receptor class I disulfides.
Wronged by Crookes
Nature, 1998
This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/authorsrights
Objective.—We sought to obtain the first effective sweep widths (ESWs) ever measured for an air-s... more Objective.—We sought to obtain the first effective sweep widths (ESWs) ever measured for an air-scent search dog unit to compare their performance to historical data from human searchers and to initially test the validity of atmospheric convection as a limiting factor in air-scent search. Methods.—We used GPS tracks and waypoints to measure lateral hit and miss distances for the dog teams during blinded, randomized training tasks during a 6-year period, calculating ESW using the crossover method. During the tasks we collected weather data for determining convection. We used nonparametric statistics and least-square regression to compare the dog ESW data with historical human data and weather conditions. Results.—The mean value of ESW for the 4 teams under all conditions was 95 m (95% CI, 44 to 145). The dog teams' performance was statistically superior to human visual searchers in detecting search subjects in low-visibility colors, but not subjects in high-visibility colors. A nonparametric correlation test of ESW vs convection gave P o .05, suggesting that convection may be an operationally significant factor in air-scent dog performance. Conclusions.—The ESW methodology is applicable to air-scent dog teams, potentially allowing search managers to make decisions in applying resources operationally, as well as improving accuracy of planning calculations. In addition, the methods described appear to be capable, given more widely representative data, of making valid statistical comparisons between different search modalities and weather and other factors.
This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright Background.—Although lost-person search managers try to direct search efforts quantitatively, it has historically been difficult to quantify the efficacy of search efforts accurately. The effective-sweep-width (ESW) methodology represents an avenue for accomplishing this goal but has not yet been widely disseminated among practitioners. Methods.—We obtained ESW values in the summer and winter in a typical disturbed-forest environment in southwest Pennsylvania. We used nonparametric statistics to compare individual ESW values for two types of search objects detected by 18 summer and 20 winter searchers, cumulating the P values for similar comparisons and correcting for false discovery via a stepped method. Results.—We detected robust differences (all at P .001) associated with search object color, season, and vegetation thickness. In contrast with earlier studies, we found a significant correlation between individual searchers' ESWs for different search objects and different types of vegetation (P .001). We also found that adolescent searchers had significantly lower ESW values than adults (P .002). Apparently significant positive correlations between time spent on the course or field search experience and ESW disappeared when teens were excluded from the comparisons. Conclusions.—These results (the first comparison of seasonal ESW effects in identical terrain) represent the first statistical demonstration that the ESW methodology provides more than enough resolution to answer fundamental questions about the efficacy of visual search for lost persons by human searchers. They also add support to the imperative of operationally disseminating these methods among search-and-rescue practitioners, and offer some initial operational lessons for search managers.
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Papers by Kenneth B Chiacchia