Using network data envelopment analysis to assess the sustainability and resilience of healthcare supply chains in response to the COVID-19 pandemic.

The widespread outbreak of a new Coronavirus (COVID-19) strain has reminded the world of the destructive effects of pandemic and epidemic diseases. Pandemic outbreaks such as COVID-19 are considered a type of risk to supply chains (SCs) affecting SC performance. Healthcare SC performance can be assessed using advanced Management Science (MS) and Operations Research (OR) approaches to improve the efficiency of existing healthcare systems when confronted by pandemic outbreaks such as COVID-19 and Influenza. This paper intends to develop a novel network range directional measure (RDM) approach for evaluating the sustainability and resilience of healthcare SCs in response to the COVID-19 pandemic outbreak. First, we propose a non-radial network RDM method in the presence of negative data. Then, the model is extended to deal with the different types of data such as ratio, integer, undesirable, and zero in efficiency measurement of sustainable and resilient healthcare SCs. To mitigate conditions of uncertainty in performance evaluation results, we use chance-constrained programming (CCP) for the developed model. The proposed approach suggests how to improve the efficiency of healthcare SCs. We present a case study, along with managerial implications, demonstrating the applicability and usefulness of the proposed model. The results show how well our proposed model can assess the sustainability and resilience of healthcare supply chains in the presence of dissimilar types of data and how, under different conditions, the efficiency of decision-making units (DMUs) changes.

Impact of the noble gas system NEX48 in Niger on the radioxenon global network coverage for the International Monitoring System of the comprehensive nuclear-test-ban treaty.

The radioxenon measurement components of the International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) play a significant role in uncovering clandestine nuclear weapons tests. The radioxenon network coverage is a critical component of the IMS capabilities. NEX48 is one of the still to-be-certified radioxenon stations and it will be the only IMS station with radioxenon measurement capabilities in the Sahara desert in Central Africa. Therefore, it may increase the radioxenon global coverage in a vast region. Seasonal contributions from NEX48 (in Niger) on the 133Xe global coverage of the IMS have been investigated in current and complete (39 stations) networks for a hypothetical one-kt subsurface nuclear explosion using atmospheric transport modelling. Adding NEX48 to the stations currently operating increased the daily global coverage by about 1.1 percent on average with most of the improvement between 15-45 N latitudes and 0-40 E longitudes. The improvements from adding NEX48 vary greatly by the seasons of the year. Removing NEX48 from the complete network leads to a daily coverage deterioration of about 0.2 percent, and the cumulative minimum coverage has a significant change.

Study of mid-latitude retrieval XCO2 greenhouse gas: Validation of satellite-based shortwave infrared spectroscopy with ground-based TCCON observations.

Carbon dioxide (CO2) is a major greenhouse gas. This study investigated the performance of three common algorithms, namely NIES, ACOS, and Remo Tec (SRFP). These algorithms were compared using GOSAT observation satellite data with reference data obtained from TCCON during the period 2009-2021. According to statistical evaluation, the SRFP and NIES algorithms achieved the lowest and highest correlation values of the 13 year (2009_2021) average of all sites, respectively. The average bias error values of NIES and ACOS was estimated to be less than that of SRFP approximately 0.5 ppm, while the bias within SRFP was of about 2 ppm. Comparing the RMSE and CRMS error values showed that the highest and lowest error values were related to the SRFP and NIES algorithms respectively, which were 0.37-1.67 and ppm 1.46-7.9. The researchers also compared them with monthly time changes based on ground measurements, and observed a time series of CO2 concentration changes that well matched the trend of gas concentration values at ground stations obtained by NIES algorithm. The results showed that in most cases NIES was an effective algorithm to retrieve carbon dioxide gas concentrations, allowing the researchers to identify the main sources of greenhouse gas emissions in different areas. The clustering result in the study area showed that the continental CO2 columnar concentration has a specific seasonal cycle, with the maximum and minimum values appearing in winter-early spring and spring-late summer, respectively. In conclusion, cluster analysis can classify the surface CO2 column concentration values and determine the spatial distribution pattern of CO2.

An investigation on the 133Xe global network coverage for the International Monitoring System of the Comprehensive Nuclear-Test-Ban Treaty.

The radionuclides part of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) global network of International Monitoring System (IMS) is based on the measurement of particles and radioactive noble gases. Forty radionuclide stations are going to be equipped with radioxenon measurement components to monitor the nuclear explosion signatures around the world. Global coverage of the noble gas IMS stations has been investigated using atmospheric transport modelling. Two years of worldwide release for a hypothetical 1-kt underground nuclear explosion and detection of 133Xe in the IMS radioxenon station locations are considered. The present and completed status were supposed as two different scenarios to estimate the daily coverage of the network. The calculated quantities were evaluated corresponding to the whole latitude/longitude grid in image-base and numerical patterns. Although the fluctuation of daily coverage is varying in time, the cumulative minimum amounts were indicated that North America has stable high coverage in the present arrangement. Moreover, after the completion of the network, this aspect will be expanded to the middle part of the Northern Hemisphere as well as the west region of the Southern Hemisphere. Finally exploring the cumulative maximum daily coverage is denoted that adding the non-operational stations to the current network has a great influence on the 20 S - 90 N latitudes to 0-180 W longitudes and about 50% effect on the network coverage (NC) of the north of Europe, South Atlantic, and Oceania. However, it has almost no impact on the values of the limited area around the middle east part of the Pacific Ocean.