A framework for determining energy use in rural food delivery services: capturing system interdependencies through an agent-based discrete-event approach

Food e-commerce has seen significant growth over the past decade that accelerated after the onset of the COVID-19 pandemic. Last-mile transportation and logistics are widely considered the most expensive and least efficient portion of the supply chain and have multiple important energy trade-offs such as cargo capacity and consumer density. Last-mile transportation energy use in rural areas is underrepresented in the literature. This study proposes a hybrid agent-based and discrete event model framework for evaluating the last-mile transportation energy use of van- and car-based food delivery services in a rural community, based on meal-kit and grocery delivery operations, respectively. This framework quantifies last-mile energy use in rural areas, and is demonstrated here using a neighborhood outside of Austin, TX as an analytical testbed. The study focuses on the effects of consumer density, cargo limitations, and vehicle speed. For the conditions examined with this framework, diesel delivery vans use more total energy than passenger cars for the same trip, though a van delivering four orders uses less energy per-order than a car delivering one order. However, there are trade-offs between vehicle type and mileage, cargo capacity, route density, and speed that are particularly important for delivery services operating in rural areas. This framework can be used by service providers to assess route-specific trade-offs for each vehicle and gauge which is preferable for given operating conditions or to evaluate the energy, and thus also cost, impact of expanding their services to rural areas.

Molecular Methods in the Identification of Pulmonary Pathologic Traits of the SARS-CoV-2 Delta Variant at Autopsy

Background: The highly contagious Delta variant of COVID-19 accounts for more than 80% of SARS-CoV-2 cases in the fall of 2021. Our aim was to determine whether molecular methods for variant and lineage detection could be utilized at autopsy to examine pathologic findings of Delta variant as compared to non-Delta variant cases. Design: We evaluated the lungs from 20 decedents with death due to SARS-CoV-2 confirmed by antemortem nasopharyngeal RTPCR in July and August 2021 (Delta wave), as well as from 40 autopsy cases prior to February 2021 with death due to SARS-CoV- 2. The patient population included males and females, with an age range of 37-67 years in the Delta group, and 44-79 In the non- Delta group. The population demographic was considered at risk for death due to COVID-19, and only one decedent, with immunosuppression, was known to be vaccinated. Lung specimens were examined on H&E and with SARS-CoV-2 nucleocapsid immunostain (IHC). Results: The time from initial symptoms to death averaged 9 days within the Delta wave and 16 days in non-Delta cases. Steroids, anticoagulation, antibiotics, and monoclonal antibody infusion were frequently part of the clinical treatment of Delta wave cases. Notably, SARS-CoV-2 PCR of lung swabs at autopsy were positive in all but one case examined in the Delta variant group, and viral genome RNA sequencing from lung at autopsy confirmed Delta variant lineage. In both groups, gross features of the lungs included edema, while grossly identifiable thrombi were more commonly seen in non-Delta variant cases. Histologic examination revealed diffuse alveolar damage (DAD) in all cases, most commonly early stage DAD in Delta variant cases. SARS-CoV-2 IHC demonstrated patchy to strong positivity in the alveoli of the majority of Delta variant cases - a finding not frequently seen in non-Delta cases. Figure 1 - 15 Conclusions: Our study is the first to incorporate PCR and viral genome sequencing from the lung at autopsy to correlate the Delta variant wave with histopathologic findings - a technique that may be useful in identifying important pathologic features of future variants. While the finding of DAD remains the same across viral variants, the majority of Delta cases showed a significant presence of SARS-CoV-2 in the lung by IHC, with minimal inflammatory infiltrate and reduced thrombotic complication. Whether these findings are the result of a shorter time interval between disease onset and death, therapeutic intervention, or increased viral load remains to be determined.

Correlation of Clinical and Histopathological Findings with Viral Variant in the Gastrointestinal Tract of COVID-19 Autopsy Cases

Background: Initial evidence has shown the occasional presence of SARS-CoV-2 in enterocytes in the intestines of patients with COVID-19. Our aim is to further assess the clinical and pathologic changes in the gastrointestinal tract caused by the highly contagious Delta (B.1.617.2) variant as compared to viral variants originating earlier in the pandemic. Design: Intestinal samples from 32 patients with death due to COVID-19 were obtained at autopsy. Decedents were males and females, with an age range of 32-73 years. Twenty-one of the decedents self-identified as Black/African American, eight as Caucasian, and three as Hispanic. Two groups were differentiated by viral genome RNA sequencing from autopsy tissue: those with Delta variant (n=16), and those with non-Delta variant (n=16). SARS-CoV-2 expression in the intestine was evaluated by immunohistochemical (IHC) detection of the SARS-CoV-2 nucleocapsid protein (N-protein). Results: Clinically, the Delta group reported diarrhea more frequently (25%) as compared to the non-Delta group (6%). Patients in the Delta group had a shorter time interval between the onset of gastrointestinal symptoms and death (mean = 19 days), as compared to the non-Delta group (mean = 25 days). Histologic examination revealed mostly normal to mild, non-specific chronic inflammation within the epithelium and lamina propria in both groups. Macrophages with positivity for N-protein IHC were present beneath the epithelium, most notably within the Delta group. N-protein positivity occurred most frequently in small submucosal and mesenteric blood vessels. Patchy positivity for N-protein in enterocytes was seen frequently in cases of Delta variant in which the time from initial symptoms to death was short (<14 days). Figure 1 - 11 Conclusions: As in prior studies, intestinal microscopic changes in COVID-19 were minimal, though our findings indicate that SARS-CoV-2 may be detected within enterocytes more frequently in the Delta group. Patients with the Delta variant experienced both a higher rate of diarrhea and a shorter interval between gastrointestinal symptom onset and death. Whether increased Nprotein in enterocytes is a result of the Delta variant itself, or earlier intestinal sampling relative to symptoms in this group, remains to be determined. Autopsy studies can add to our understanding of the effects of COVID-19 on the digestive system, by allowing a greater volume of tissue sampling, as well as temporal sampling relative to disease onset that is not always possible at endoscopy.