Corporate real estate analysis: evaluating telecom branch efficiency in Greece

This paper proposes productivity analysis for evaluating the relative efficiency in corporate real estate usage across decision-making units. Using data from the Greek Telecommunications Organization (GTO), we measure the productivity of 127 braches using the number of employees and the total area covered per building as inputs and the number of telephony access lines as outputs. We apply three non-parametric Data Envelopment Analysis (DEA) models assuming: constant returns to scale (CRS), variable returns to scale (VRS) and slacks-based measures (SBM), respectively. We discuss how the proposed approach can provide real estate managers and analysts a multi informational tool that allows the quantification of targets and may serve as a guide tool for the efficient employment of real estate assets

Cabbage and fermented vegetables : From death rate heterogeneity in countries to candidates for mitigation strategies of severe COVID-19

Large differences in COVID-19 death rates exist between countries and between regions of the same country. Some very low death rate countries such as Eastern Asia, Central Europe, or the Balkans have a common feature of eating large quantities of fermented foods. Although biases exist when examining ecological studies, fermented vegetables or cabbage have been associated with low death rates in European countries. SARS-CoV-2 binds to its receptor, the angiotensin-converting enzyme 2 (ACE2). As a result of SARS-CoV-2 binding, ACE2 downregulation enhances the angiotensin II receptor type 1 (AT(1)R) axis associated with oxidative stress. This leads to insulin resistance as well as lung and endothelial damage, two severe outcomes of COVID-19. The nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is the most potent antioxidant in humans and can block in particular the AT(1)R axis. Cabbage contains precursors of sulforaphane, the most active natural activator of Nrf2. Fermented vegetables contain many lactobacilli, which are also potent Nrf2 activators. Three examples are: kimchi in Korea, westernized foods, and the slum paradox. It is proposed that fermented cabbage is a proof-of-concept of dietary manipulations that may enhance Nrf2-associated antioxidant effects, helpful in mitigating COVID-19 severity.Peer reviewe

Nrf2-interacting nutrients and COVID-19 : time for research to develop adaptation strategies

There are large between- and within-country variations in COVID-19 death rates. Some very low death rate settings such as Eastern Asia, Central Europe, the Balkans and Africa have a common feature of eating large quantities of fermented foods whose intake is associated with the activation of the Nrf2 (Nuclear factor (erythroid-derived 2)-like 2) anti-oxidant transcription factor. There are many Nrf2-interacting nutrients (berberine, curcumin, epigallocatechin gallate, genistein, quercetin, resveratrol, sulforaphane) that all act similarly to reduce insulin resistance, endothelial damage, lung injury and cytokine storm. They also act on the same mechanisms (mTOR: Mammalian target of rapamycin, PPAR gamma:Peroxisome proliferator-activated receptor, NF kappa B: Nuclear factor kappa B, ERK: Extracellular signal-regulated kinases and eIF2 alpha:Elongation initiation factor 2 alpha). They may as a result be important in mitigating the severity of COVID-19, acting through the endoplasmic reticulum stress or ACE-Angiotensin-II-AT(1)R axis (AT(1)R) pathway. Many Nrf2-interacting nutrients are also interacting with TRPA1 and/or TRPV1. Interestingly, geographical areas with very low COVID-19 mortality are those with the lowest prevalence of obesity (Sub-Saharan Africa and Asia). It is tempting to propose that Nrf2-interacting foods and nutrients can re-balance insulin resistance and have a significant effect on COVID-19 severity. It is therefore possible that the intake of these foods may restore an optimal natural balance for the Nrf2 pathway and may be of interest in the mitigation of COVID-19 severity

The balanced cargo vehicle routing problem with time windows

This paper addresses a variant of the vehicle routing problem with time windows (VRPTW) that targets the balancing of the load carried by each active vehicle (balanced cargo VRPTW or BCVRPTW). A new approach, based on the free disposal hull (FDH) method of data envelopment analysis, is proposed; it consists of an initial, feasible route generation procedure that employs an effective heuristic for the VRPTW, followed by an iterative method for selecting routes on the efficiency frontier, according to the criteria of the BCVRPTW and the notion of non-dominated solutions embedded within FDH. This new approach produces, according to our computational evaluation, very good results for the BCVRPTW, and can serve as the basis for solving real-life vehicle routing problems.Vehicle routing with time windows Heuristics Data envelopment analysis Free disposal hull method

A problem generator-solver heuristic for vehicle routing with soft time windows”,

Abstract In this paper we consider the vehicle routing problem with soft time window constraints (VRPSTW), in which vehicles are allowed to service customers before and after the earliest and latest time window bounds, respectively. This relaxation comes at the expense of appropriate penalties that re ect the e ect that time window violations have on the customers' satisfaction. The problem is of particular importance for eet planning as it allows decision-makers from both the logistics and marketing-sales side to determine minimal eet sizes by appropriate contract negotiations for order delivery times. To solve the problem, we couple the nearest-neighbour method with a problem generator that provides, in a structured manner, numerous instances that result from the manipulation of the level of time window violations and the population of customers that allow such violations. The proposed heuristic results in solutions that reduce the number of vehicles required for the hard case and provide minimal violations of time windows. Computational results on a set of benchmark problems show that our method outperforms previous approaches to the vehicle routing problem with soft time windows, and that it can serve as the basis for e cient and e ective eet planning.

A problem generator-solver heuristic for vehicle routing with soft time windows

In this paper we consider the vehicle routing problem with soft time window constraints (VRPSTW), in which vehicles are allowed to service customers before and after the earliest and latest time window bounds, respectively. This relaxation comes at the expense of appropriate penalties that reflect the effect that time window violations have on the customers' satisfaction. The problem is of particular importance for fleet planning as it allows decision-makers from both the logistics and marketing-sales side to determine minimal fleet sizes by appropriate contract negotiations for order delivery times. To solve the problem, we couple the nearest-neighbour method with a problem generator that provides, in a structured manner, numerous instances that result from the manipulation of the level of time window violations and the population of customers that allow such violations. The proposed heuristic results in solutions that reduce the number of vehicles required for the hard case and provide minimal violations of time windows. Computational results on a set of benchmark problems show that our method outperforms previous approaches to the vehicle routing problem with soft time windows, and that it can serve as the basis for efficient and effective fleet planning.Routing Heuristics Logistics Transportation Fleet planning

An introduction to decision making using the elimination method of Fourier-Motzkin

The paper introduces the decision-making through a system of inequalities for high-school students and first-year undergraduate students. The objective of this paper is to enable the students to understand the importance of mathematics in real business application problems. Moreover, we present a production problem and highlight the set of solutions for the problem. The set of solutions is defined by the system of inequalities resulting from available resources for production, storage, and consumption. Furthermore, we introduce the elimination method of Fourier-Motzkin. The method helps us to find the optimum solution for the production problem by solving systems of inequalities without using linear programming

A Service Infrastructure for E-Science: the case of the ARION System

The ARION system provides basic e-services of search and retrieval of objects in scientific collections, such as, data sets, simulation models and tools necessary for statistical and/or visualization processing. These collections may represent application software of scientific areas, they reside in geographically disperse organizations and constitute the system content. The user as part of the retrieval mechanism may dynamically invoke on-line computations of scientific data sets when the latter are not found into the system. Thus ARION provides the basic infrastructure for accessing and producing scientific information in an open distributed and federated system. More advanced e-services, which depend on the scientific content of the system, can be built upon this infrastructure, such as decision making, and/or policy support using various information brokering techniques