On the resistivity at low temperatures in electron-doped cuprate superconductors

We measured the magnetoresistance as a function of temperature down to 20mK and magnetic field for a set of underdoped PrCeCuO (x=0.12) thin films with controlled oxygen content. This allows us to access the edge of the superconducting dome on the underdoped side. The sheet resistance increases with increasing oxygen content whereas the superconducting transition temperature is steadily decreasing down to zero. Upon applying various magnetic fields to suppress superconductivity we found that the sheet resistance increases when the temperature is lowered. It saturates at very low temperatures. These results, along with the magnetoresistance, cannot be described in the context of zero temperature two dimensional superconductor-to-insulator transition nor as a simple Kondo effect due to scattering off spins in the copper-oxide planes. We conjecture that due to the proximity to an antiferromagnetic phase magnetic droplets are induced. This results in negative magnetoresistance and in an upturn in the resistivity.Comment: Accepted in Phys. Rev.

New prospects for Ethyl formate as a fumigant for the date industry

Date infestation of nitidulid beetles poses a serious contamination problem for which methyl bromide (MB) provided a solution. However, because of the phase out of MB, alternatives were investigated. Thermal disinfestation method has been successfully applied to some dry date varieties except to Deglet-Noor, Zahidi, and Ameri which are handled in crates of 200 kg to 400 kg. Therefore, thermal disinfestation was not successful because of delayed heating due to the resistance of the dates to hot airflow. The fumigant formulation VapormateTM was tested as alternative to MB for the disinfestation (proportion of insects found outside the feeding sites) and control of nitidulid beetles from artificial feeding sites at laboratory and for  dates in crates at semi-commercial conditions. VapormateTM contains 16.7% ethyl formate mixed with carbon dioxide. At laboratory conditions the effect of various dosages of VapormateTM was tested at 30oC and at fixed exposure time of 12 h. Exposure of infested artificial feeding sies by larvae of Carpophilus spp. to the concentration of 280 g m-3 of VapormateTM caused 69.3% disinfestation and 79.9% mortality, 350 g m-3 resulted in 72.7% disinfestation and 98.8% of mortality and the optimal results were obtained at 420 g m-3 that caused 69.6% disinfestations and 100% mortality. Commercial pilot-plant tests were carried out by applying 420 g m-3 VapormateTM for 12 h in a 9 m3 flexible liner made of laminate composed of polypropylene/aluminum/polyethylene to cover crates containing infested dates. Disinfestation was tested on naturally infested dates that resulted in an average 100% disinfestation and 95% mortality, while with the artificially infested dates, disinfestation was 97% and mortality 96%. In a second series of tests, a commercial rigid fumigation chamber of 95.6 m3 was used. After 12 h exposure, 100% mortality was recorded in all date samples. Following the promising results, VapormateTM was registered in Israel for use by the date industry as an alternative to MB. Keywords: Date, Nitidulid beetles, Ethyl formate, VapormateTM, Fumigation

A novel approach to the protection of cocoa beans by preventing free fatty acid formation under hermetic storage

Hermetic storage has provided a successful storage method for the protection of dry cocoa beans by replacing fumigants for insect control and for quality preservation. Hermetic storage is achieved in specially constructed flexible plastic structures and is based on the principle of generation of an oxygen-depleted, carbon dioxide-enriched interstitial atmosphere caused by the respiration of the living organisms in the ecological system of a sealed storage. An increase in free fatty acids (FFA) content in dry cocoa beans is a significant factor that determines its quality preservation. After fermentation of the beans, moisture content (m.c.) is usually high that poses a risk for the rise of FFA in the beans. Tests were carried out to study the effects of hermetic storage of dry cocoa beans under aerobic and hermetically sealed conditions on the development of FFA's in the beans at 7.0%, 7.5%, and 8.0% m.c. for periods of 90 and 160 d at 30°C. The beans under hermetic conditions responded by creating progressive depleted oxygen conditions that were accompanied by the increased carbon dioxide due to the respiration of the beans. The lowest oxygen concentration took place at 7.0% m.c. after 35 d, at 7.5% m.c. after 29 d, at 8.0% m.c. after 26 d of storage and thereafter, no significant increase in oxygen concentration was observed. The FFA content of cocoa beans at 7.0%, 7.5%, and 8.0% m.c. under hermetic conditions of 30°C remained below or close to 1.0% after 90 and 160 d of storage. This was more comparable to the results obtained when the beans were stored at 4oC rather than the controls. In comparison, the aerated control stored at 30°C showed marked increase in FFA levels of up to 1.48%. Keywords: Hermetic storage, Modified Atmospheres, Cocoa beans, Quality preservation, Storage insect control, Flexible storage structures

The Future Environmental and Health Impacts of Coal

In the United States, coal consumption in the last 12 years has declined from 1,045,140 million short tons in 2007 to 539,420 million short tons in 2019, a decrease of almost 50%. During that period the number of electric power coal generators has declined from 1,470 to 738 accounting for 21% of capacity. An even more dramatic decrease in coal use has occurred in Western Europe. This significant reduction in coal use and the concomitant closure of coal mines and coal-burning power plants will result in substantially cleaner air, reductions in respiratory problems such as asthma, less heart disease, fewer hospitalizations, and other health benefits, as well as a reduction in occupational health problems such as silicosis and Coal Workers’ Pneumoconiosis (Black Lung Disease). However, in China, India, Russia and in several other Asian countries some projections indicate an increase in coal production and use. In some situations, the coal is burned in old, highly polluting power plants. In these regions the health impacts of coal use could worsen. In addition, millions of people in these regions still burn coal in their homes resulting in maximal exposure to the pollutants such as arsenic, selenium, fluorine, and mercury released from coal combustion

Item Ordering and Computerized Classification Tests With Cluster-Based Scoring: An Investigation of the Countdown Method

The countdown method is a well-known approach to reducing the average length of screening instruments that are presented by computer. In the countdown method, testing is terminated once the result of the screener (“positive” or “negative”) has been unambiguously determined from prior answers. Previous research has examined whether presenting dichotomously scored items in order from “least to most frequently endorsed” or “most to least frequently endorsed” is more efficient when the countdown method is used. The current study describes the Mean Score procedure, an extension of the above item ordering procedures to polytomously scored items, and evaluates its efficiency relative to the distribution of other possible item orderings in 2 real-data simulations. Both simulations involve item responses to the Posttraumatic Stress Disorder (PTSD) Checklist for DSM–5 (PCL-5). In the first simulation, items were scored polytomously, and a single cutoff point was used to determine the screening result. In the second simulation, items were converted to dichotomous scores, as well as categorized into 4 clusters; a positive result for the entire assessment was obtained if and only if a positive result was obtained for each cluster. The latter simulation also investigated the effect of reordering the clusters themselves on the efficiency of the countdown method. Results indicated that the Mean Score procedure does not necessarily produce the optimal ordering, but tends to assemble an efficient item ordering relative to the distribution of possible orderings. In the second simulation, reordering the clusters themselves affected efficiency. Future research directions are suggested

Customized computer-based administration of the PCL-5 for the efficient assessment of PTSD:A proof-of-principle study

Objective: To investigate the potential of customized computer-based testing procedures to reduce the mean test length of the Posttraumatic Stress Checklist for DSM-5 (PCL-5). Method: A retrospective analysis was conducted using responses from 942 adults who had completed the full-length (20-item) PCL-5 in the aftermath of Hurricane Sandy. The abilities of 2 testing procedures, curtailment and stochastic curtailment, to lessen the instrument's mean test length while maintaining the same result as the full-length PCL-5 ("positive" or "negative") were evaluated in a post hoc simulation. Curtailment and stochastic curtailment track a respondent's answers as she takes the instrument and stop the test if future items are unable or unlikely to change the result. The performance of each procedure was recorded under 2 scoring methods: a total-score-based method and a cluster-based method. Each procedure's sensitivity, specificity, and overall agreement with the full-length PCL-5 were computed. Results: Curtailment reduced the mean test length by 40% under the total-score-based method, and by more than 70% under the cluster-based method, while exhibiting 100% sensitivity, specificity, and overall agreement with the full-length PCL-5. Stochastic curtailment reduced the mean test length by up to 88% under the total-score-based method, and up to 84% under the cluster-based method, while always exhibiting at least 92% sensitivity and 99.8% overall agreement, as well as 100% specificity, for the full-length PCL-5. Conclusions: Curtailment and stochastic curtailment have potential to enhance the efficiency of the PCL-5 when this assessment is administered by computer. The 2 procedures should be evaluated in future prospective studies. (PsycINFO Database Recor