An Evaluation of The Effectiveness of Adaptive Histogram Equalization for Contrast Enhancement

Adaptive Histogram Equalization (AHE), a method of contrast enhancement which is sensitive to local spatial information in an image, has been proposed as a solution to the problem of the inability of ordinary display devices to depict the full dynamic intensity range in some medical images. This method is automatic, reproducible, and simultaneously displays most of the information contained in the grey-scale contrast of the image. However, it has not been known whether the use of AHE causes the loss of diagnostic information relative to the commonly-used method intensity windowing. In the current work, AHE and intensity windowing are compared using psychophysical observer studies. In studies performed at North Carolina Memorial Hospital, experienced radiologists were shown clinical CT images of the chest. Into some of the images, appropriate artificial lesion were introduced; the physicians were then shown the images processed with both AHE and intensity windowing. They were asked to assess the probability that as given image contained the artificial lesion, and their accurate was measured. The results of these experiments shown that for this particular diagnostic task, there was no significant difference in the ability of the two methods to depict luminance contrast; thus, further evaluation of AHE using controlled clinical trials is indicated

Aboveground carbon responses to experimental and natural hurricane impacts in a subtropical wet forest in Puerto Rico

Climate change and disturbance make it difficult to project long-term patterns of carbon sequestration in tropical forests, but large ecosystem experiments in these forests can inform predictions. The Canopy Trimming Experiment (CTE) manipulates two key components of hurricane disturbance, canopy openness and detritus deposition, in a tropical forest in Puerto Rico. We documented how the CTE and a real hurricane affected tree recruitment, biomass, and aboveground carbon storage over 15 years. In the CTE treatments, we trimmed branches, but we did not fell trees. We expected that during the 14-year period after initial canopy trimming, regrowth of branches and stems and stem recruitment stimulated by increased light and trimmed debris would help restore biomass and carbon loss due to trimming. Compared to control plots, in the trimmed plots recruitment of palms and dicot trees increased markedly after trimming, and stem diameters of standing trees increased. Data showed that recruitment of small trees adds little to aboveground carbon, compared to the amount in large trees. Nevertheless, this response restored pretreatment biomass and carbon in the experimental period. In particular, the experimental additions of trimmed debris on the forest floor seemed to stimulate increase in aboveground carbon. Toward the end of the experimental period, Hurricane Maria (Category 4 hurricane) trimmed and felled some trees but reduced aboveground carbon less in the plots (including untrimmed plots) than experimental trimming had. Thus, it appears that the amount of regrowth recorded after experimental trimming could also restore aboveground carbon in the forest after a severe hurricane in the same time span. However, Hurricane Maria, unlike the trimming treatments, felled large trees, and it may be that with predicted, more frequent severe hurricanes, that the continued loss of large trees would over the long term decrease aboveground carbon stored in this Puerto Rican forest and likewise in other tropical forests affected by cyclonic storms

Timing of Esophagectomy after Neoadjuvant Chemoradiation Therapy Affects the Incidence of Anastomotic Leaks

Background: Neoadjuvant chemoradiation therapy (nCRT) has become the standard of care for esophageal cancer patients prior to esophagectomy. However, the optimal timing for surgery after completion of nCRT remains unclear. Methods: A retrospective review was performed of patients who underwent esophagectomy with cervical anastomosis for esophageal cancer at a single institution between January 2000 and June 2015. Patients were categorized into 3 cohorts: those who did not receive nCRT prior to esophagectomy (no nCRT), those who underwent esophagectomy within 35 days after nCRT (≤35d), and those who underwent esophagectomy more than 35 days after nCRT (>35d). Results: A total of 366 esophagectomies were performed during the study period, and 348 patients met the inclusion criteria. Anastomotic leaks occurred in 11.8% of all patients included in the study (41 of 348). Within each cohort, anastomotic leaks were detected in 14.7% of patients (17 of 116) in the no nCRT cohort, 7.3% (13 of 177) in the ≤35d cohort, and 20.0% (11 of 55) in the >35d cohort (p=0.020). Significant differences in the occurrence of anastomotic leaks were observed between the no nCRT and ≤35d cohorts (p=0.044), and between the ≤35d and >35d cohorts (p=0.007). Conclusion: Esophagectomy with cervical anastomosis within 35 days of nCRT resulted in a lower percentage of anastomotic leaks

Plasticity of host selection by malaria vectors of Papua New Guinea

Background Host selection is an important determinant of vectorial capacity because malaria transmission increases when mosquitoes feed more on humans than non-humans. Host selection also affects the outcome of long-lasting insecticidal nets (LLIN). Despite the recent nationwide implementation of LLIN-based malaria control program in Papua New Guinea (PNG), little is known about the host selection of the local Anopheles vectors. This study investigated the host selection of Anopheles vectors in PNG. Methods Blood-engorged mosquitoes were sampled using the barrier screen method and blood meals analyzed for vertebrate host source with PCR-amplification of the mitochondrial cytochrome b gene. Abundance of common hosts was estimated in surveys. The test of homogeneity of proportions and the Manly resource selection ratio were used to determine if hosts were selected in proportion to their abundance. Results Two thousand four hundred and forty blood fed Anopheles females of seven species were sampled from five villages in Madang, PNG. Of 2,142 samples tested, 2,061 (96.2%) yielded a definitive host source; all were human, pig, or dog. Hosts were not selected in proportion to their abundance, but rather were under-selected or over-selected by the mosquitoes. Four species, Anopheles farauti (sensu stricto) (s.s.), Anopheles punctulatus (s.s.), Anopheles farauti no. 4 and Anopheles longirostris, over-selected humans in villages with low LLIN usage, but over-selected pigs in villages with high LLIN usage. Anopheles koliensis consistently over-selected humans despite high LLIN usage, and Anopheles bancroftii over-selected pigs. Conclusions The plasticity of host selection of an Anopheles species depends on its opportunistic, anthropophilic or zoophilic behavior, and on the extent of host availability and LLIN usage where the mosquitoes forage for hosts. The high anthropophily of An. koliensis increases the likelihood of contacting the LLIN inside houses. This allows its population size to be reduced to levels insufficient to support transmission. In contrast, by feeding on alternative hosts the likelihood of the opportunistic species to contact LLIN is lower, making them difficult to control. By maintaining high population size, the proportion that feed on humans outdoors can sustain residual transmission despite high LLIN usage in the village

Measuring the Intrapersonal Component of Psychological Empowerment: Confirmatory Factor Analysis of the Sociopolitical Control Scale

The Sociopolitical Control Scale (SPCS) is a widely used measure of the intrapersonal component of psychological empowerment. Confirmatory factor analyses (CFA) were conducted with data from two samples to test the hypothesized structure of the SPCS, the potential effects of method bias on the measure's psychometric properties, and whether a revised version of the scale (SPCS‐R) yielded improved model fit. Sample 1 included 316 randomly selected community residents of the Midwestern United States. Sample 2 included 750 community residents of the Northeastern U.S. Results indicated that method bias from the use of negatively worded items had a significant effect on the factor structure of the SPCS. CFA of the SPCS‐R, in which negatively worded items were rephrased so that all statements were positively worded, supported the measure's hypothesized two‐factor structure (i.e., leadership competence and policy control). Subscales of the SPCS‐R were found reliable and related in expected ways with measures of community involvement. Implications of the study for empowerment‐based research and practice are described, and strategies to further develop the SPCS are discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/117223/1/ajcp9070.pd

Solar radiation and soil moisture drive tropical forest understory responses to experimental and natural hurricanes

Tropical forest understory regeneration occurs rapidly after disturbance with compositional trajectories that depend on species availability and environmental conditions. To predict future tropical forest regeneration dynamics, we need a deeper understanding of how pulse disturbance events, like hurricanes, interact with environmental variability to affect understory demography and composition. We examined fern and sapling mortality, recruitment, and community composition in relation to solar radiation and soil moisture using 17 years of forest dynamics data (2003–2019) from the Canopy Trimming Experiment in the Luquillo Experimental Forest, Puerto Rico. Solar radiation increased 150% and soil moisture increased 40% following canopy trimming of experimental plots relative to control plots. All plots were disturbed in 2017 by Hurricanes Irma and Maria, so experimentally trimmed plots presented the opportunity to study the effects of multiple hurricanes, while control plots isolated the effects of a single natural hurricane. Recruitment rates maximized at 0.14 individuals/plot/month for ferns and 0.20 stems/plot/month for saplings. Recruitment and mortality were distributed more evenly over the 17 years of monitoring in experimentally trimmed plots than in control plots; however, following Hurricane Maria demographic rates substantially increased in control plots only. In experimentally trimmed plots, the largest community compositional shifts occurred as a result of the trimming events, and compositional changes were greatest for control plots after Hurricane Maria in 2017. Pioneer tree and fern species increased in abundance in response to both simulated and natural hurricanes. Following Hurricane Maria, two dominant pioneer species, Cyathea arborea and Cecropia schreberiana, recruited abundantly, but only in control plots. In trimmed plots, increased solar radiation and soil moisture shifted understory species composition steadily toward pioneer and secondary-successional species, with soil moisture interacting strongly with canopy trimming. Thus, both solar radiation and soil moisture are environmental drivers affecting pioneer species recruitment following disturbance, which interact with canopy opening following hurricanes. Our results suggest that if hurricane disturbances increase in frequency and severity, as suggested by climate change predictions, the understory regeneration of late-successional species, such as Manilkara bidentata and Sloanea berteroana, which prefer deeper shade and slightly drier soil microsites, may become imperiled

Numerical modeling of CLT diaphragms tested on a shake-table experiment

Current standards and existing literature provide very limited information regarding the design of cross-laminated timber (CLT) floor diaphragms. In addition, limited procedures exist to develop analytical models to estimate the deformation response of CLT floor diaphragms. This paper presents a modelling approach that captures the response of CLT timber diaphragms, with a special focus on CLT spline panel-to-panel connections. The modeling approach is validated through the comparison of the results of the computation model with experimental data obtained from a series of shake-tables test performed on a two-story full-scale building tested in the summer of 2017 at UC San Diego Large High Performance Outdoor Shake Table. The two-story building included two diaphragm designs at each floor level. The first solution consists of CLT panels connected with plywood surface splines that are fastened using self-tapping screws, while the second consists of a CLT-concrete composite floor solution. Results from the nonlinear pushover analysis describe accurately the experimental data obtained.(undefined