Optimizing multiple truck trips in a cooperative environment through MILP and Game Theory

Today, the challenge of economy regarding freight transport is to generate flows of goods extremely fast, handling information in short times, optimizing decisions, and reducing the percentage of vehicles that circulate empty over the total amount of transportation means, with benefits to roads congestion and the environment, besides economy. Logistic operators need to pose attention on suitable planning methods in order to reduce their costs, fuel consumption and emissions, as well as to gain economy of scale. To ensure the maximum efficacy, planning should be also based on cooperation between the involved subjects. Collaboration in logistics is an effective approach for business to obtain a competitive edge. In a successful collaboration, parties involved from suppliers, customers, and even competitors perform a coordinated effort to realize the potential benefit of collaboration, including reduced costs, decreased lead times, and improved asset utilization and service level. In addition to these benefit, having a broader supply chain perspective enables firms to make better-informed decisions on strategic issues. The first aim of the present Thesis is to propose a planning approach based on mathematical programming techniques to improve the efficiency of road services of a single carrier combining multiple trips in a port environment (specifically, import, export and inland trips). In this way, in the same route, more than two transportation services can be realized with the same vehicle thus significantly reducing the number of total empty movements. Time windows constraints related to companies and terminal opening hours as well as to ship departures are considered in the problem formulation. Moreover, driving hours restrictions and trips deadlines are taken into account, together with goods compatibility for matching different trips. The second goal of the Thesis is to define innovative planning methods and optimization schemes of logistic networks in which several carriers are present and the decisional actors operate in a cooperative scenario in which they share a portion of their demand. The proposed approaches are characterized by the adoption both of Game Theory methods and of new original methods of profits distribution

Combining multiple trips in a port environment for empty movements minimization

Road transportation represents the most used transportation mode to cover short distances. However, structural lack of planning and optimization in road transportation creates negative effects both for companies and for the social community, such as environmental pollution, economic loss and road congestion. These effects are mainly due to the fact that a lack of planning can yield the necessity of a huge number of empty trips. Usually trucks that pick up or deliver a full container in a port must return back the empty container to the place where the trip started, so performing one leg of the total trip without payload. The aim of the present paper is to propose a mathematical approach for combining multiple trips in a port environment (specifically, import, export and inland trips) by considering the opportunity of carrying two 20 ft containers simultaneously on the same truck and by using the same load unit if possible. In this way, in the same route, more than two nodes can be visited with the same vehicle thus significantly reducing the number of total empty movements. Time windows constraints related to companies and terminal opening hours as well as to ship departures are considered in the problem formulation. Moreover driving hours restrictions and trips deadlines are taken into account, together with goods compatibility for matching different trips. An experimental campaign based on real data is discussed in the paper

Will the Antarctic tardigrade Acutuncus antarcticus be able to withstand environmental stresses related to global climate change?

Because conditions in continental Antarctica are highly selective and extremely hostile to life, its biota is depauperate, but well adapted to live in this region. Global climate change has the potential to impact continental Antarctic organisms because of increasing temperatures and ultraviolet radiation. This research evaluates how ongoing climate changes will affect Antarctic species, and whether Antarctic organisms will be able to adapt to the new environmental conditions. Tardigrades represent one of the main terrestrial components of Antarctic meiofauna; therefore, the pan-Antarctic tardigrade Acutuncus antarcticus was used as model to predict the fate of Antarctic meiofauna threatened by climate change. Acutuncus antarcticus individuals tolerate events of desiccation, increased emperature and UV radiation. Both hydrated and desiccated animals tolerate increases in UV radiation, even though the desiccated animals are more resistant. Nevertheless, the survivorship of hydrated and desiccated animals is negatively affected by the combination of temperature and UV radiation, with the hydrated animals being more tolerant than desiccated animals. Finally, UV radiation has a negative impact on the life history traits of successive generations of A. antarcticus, causing an increase in egg reabsorption and teratological events. In the long run, A. antarcticus could be at risk of population reductions or even extinction. Nevertheless, because the changes in global climate will proceed gradually and an overlapping of temperature and UV increase could be limited in time, A. antarcticus, as well as many other Antarctic organisms, could have the potential to overcome global warming stresses, and/or the time and capability to adapt to the new environmental conditions

A DNA barcoding approach in the study of tardigrades

DNA barcoding is a technique proposed by Hebert and coworkers in 2003 for discriminating species through analysis of a single gene barcode locus. It aims to obtain a better taxonomic resolution than that achieved through morphological studies, and to avoid the decline in taxonomic knowledge. Today DNA barcoding is a global enterprise, and the implementation of the idea has seen a rapid rise (more than 1900 papers published to date on different organisms). Nonetheless, controversy still arises regarding barcoding and taxonomy. It is important to note that DNA barcoding does not focus on building a tree-of-life or on doing DNA taxonomy, even though sometimes it has been used for these purposes. DNA barcoding rather focuses on producing a universal molecular identification key based on strong taxonomic knowledge that should be included in the barcode reference library. In the phylum Tardigrada, DNA barcoding represents a recent approach to species identification and to help in solving taxonomic problems, especially considering the diminutive size of these animals and the paucity of morphological characters useful for taxonomy. In the framework of the MoDNA Project (Morphology and DNA), carried out by our research group in collaboration with several colleagues, we are combining the study of a fragment of the mitochondrial cytochrome c oxidase subunit I gene (cox1) with morphological data, in a wide sense (cuticular structures, chromosomes, data on sex ratio and reproduction), to form an integrative taxonomy approach for tardigrade species identification. We believe that without verified reference sequences from voucher specimens that have been authenticated by qualified taxonomists, there is no reliable library for newly generated sequences with which to be compared. Methods and protocols for standardized results are focused on obtaining tight correspondence between tardigrade morphology (and egg shell morphology, when useful), possibly both light and scanning electron microscopy images, and molecular sequence. This approach is particularly useful in describing new species, and important when applied on material collected in species type localities. Results using this approach are presented, primarily focusing on a number of species from the so-called “Macrobiotus hufelandi group”

Production of reactive oxygen species and involvement of bioprotectants during anhydrobiosis in the tardigrade Paramacrobiotus spatialis

Water unavailability is an abiotic stress causing unfavourable conditions for life. Nevertheless, some animals evolved anhydrobiosis, a strategy allowing for the reversible organism dehydration and suspension of metabolism as a direct response to habitat desiccation. Anhydrobiotic animals undergo biochemical changes synthesizing bioprotectants to help combat desiccation stresses. One stress is the generation of reactive oxygen species (ROS). In this study, the eutardigrade Paramacrobiotus spatialis was used to investigate the occurrence of ROS associated with the desiccation process. We observed that the production of ROS signifcantly increases as a function of time spent in anhydrobiosis and represents a direct demonstration of oxidative stress in tardigrades. The degree of involvement of bioprotectants, including those combating ROS, in the P. spatialis was evaluated by perturbing their gene functions using RNA interference and assessing the successful recovery of animals after desiccation/rehydration. Targeting the glutathione peroxidase gene compromised survival during drying and rehydration, providing evidence for the role of the gene in desiccation tolerance. Targeting genes encoding glutathione reductase and catalase indicated that these molecules play roles during rehydration. Our study also confrms the involvement of aquaporins 3 and 10 during rehydration. Therefore, desiccation tolerance depends on the synergistic action of many diferent molecules working together

Resistance to Extreme Stresses by a Newly Discovered Japanese Tardigrade Species, Macrobiotus kyoukenus (Eutardigrada, Macrobiotidae)

Tardigrades are small micrometazoans able to resist several environmental stresses in any stage of their life cycle. An integrated analysis of tardigrade specimens collected in Tsukuba (Japan) revealed a peculiar morphology and a new sensory field in the cloaca. Molecular taxonomy and phylogenetic analysis on different genes (COI, ITS2, 18S and 28S) confirmed that this population is a new species, Macrobiotus kyoukenus sp. nov., belonging to the widespread Macrobiotus hufelandi group. The stress resistance capabilities of M. kyoukenus sp. nov. have been tested by submitting animals to extreme desiccation, rapid freezing, and high levels of ultraviolet radiations (UVB and UVC). Animals were able to survive desiccation (survivorship 95.71 ± 7.07%) and freezing up to -80 °C (82.33 ± 17.11%). Both hydrated and desiccated animals showed a high tolerance to increasing UV radiations: hydrated animals survived to doses up to 152.22 kJ m−2 (UVB) and up to 15.00 kJ m−2 (UVC), while desiccated specimens persisted to radiations up to 165.12 kJ m−2 (UVB) and up to 35.00 kJ m−2 (UVC). Present data contribute to the discovery of a larger tardigrade biodiversity in Japan, and the tolerance capabilities of M

The Macrobiotus persimilis-polonicus complex (Eutardigrada, Macrobiotidae), another example of problematic species identification, with the description of four new species.

In the phylum Tardigrada, as in other meiofauna taxa, the small size of the animals and the paucity of morphological characters useful for taxonomy present a challenge for systematic studies. For this reason, an integrated approach is increasingly desirable, including at least morphology, morphometry and molecular investigations, and possibly reproductive biology, ecology, physiology and other approaches. In this light, we analysed different populations of Macrobiotus (Eutardigrada, Macrobiotidae) from Italy, France and Poland with persimilis type of eggs and with very similar animals. We compared the morphology and morphometry of the type materials of Macrobiotus persimilis and Macrobiotus polonicus with those of newly collected populations, which were also analysed from a molecular (cox1 mtDNA and 18S rDNA) and reproductive perspective. Our data confirmed the presence of a persimilis-polonicus complex, recognizable by very similar characters of the animals and the eggs. It comprises M. persimilis, M. polonicus, four new morphologically distinguishable species described in this paper (Macrobiotus dolosus sp. nov., Macrobiotus siderophilus sp. nov., Macrobiotus fontourai sp. nov., Macrobiotus muralis sp. nov.) and other species very similar from a morphological point of view. Molecular data, retrieved for the first three new species, reveal that they have very high genetic distances for cox1 (16.0–17.7%). Furthermore, we have been able to verify that more than one species of this complex can cohabit in the same moss. A wider persimilis group, comprising the persimilis-polonicus complex, could also be identified only on morphological basis

Antioxidant Response during the Kinetics of Anhydrobiosis in Two Eutardigrade Species

Anhydrobiosis, a peculiar adaptive strategy existing in nature, is a reversible capability of organisms to tolerate a severe loss of their body water when their surrounding habitat is drying out. In the anhydrobiotic state, an organism lacks all dynamic features of living beings since an ongoing metabolism is absent. The depletion of water in the anhydrobiotic state increases the ionic concentration and the production of reactive oxygen species (ROS). An imbalance between the increased production of ROS and the limited action of antioxidant defences is a source of biomolecular damage and can lead to oxidative stress. The deleterious effects of oxidative stress were demonstrated in anhydrobiotic unicellular and multicellular organisms, which counteract the effects using efficient antioxidant machinery, mainly represented by ROS scavenger enzymes. To gain insights into the dynamics of antioxidant patterns during the kinetics of the anhydrobiosis of two tardigrade species, Paramacrobiotus spatialis and Acutuncus antarcticus, we investigated the activity of enzymatic antioxidants (catalase, superoxide dismutase, glutathione peroxidase, and glutathione reductase) and the amount of non-enzymatic antioxidants (glutathione) in the course of rehydration. In P. spatialis, the activity of catalase increases during dehydration and decreases during rehydration, whereas in A. antarcticus, the activity of superoxide dismutase decreases during desiccation and increases during rehydration. Genomic varieties, different habitats and geographical regions, different diets, and diverse evolutionary lineages may have led to the specialization of antioxidant strategies in the two specie

Tardigrades Use Intrinsically Disordered Proteins to Survive Desiccation

Tardigrades are microscopic animals that survive a remarkable array of stresses, including desiccation. How tardigrades survive desiccation has remained a mystery for more than 250 years. Trehalose, a disaccharide essential for several organisms to survive drying, is detected at low levels or not at all in some tardigrade species, indicating that tardigrades possess potentially novel mechanisms for surviving desiccation. Here we show that tardigrade-specific intrinsically disordered proteins (TDPs) are essential for desiccation tolerance. TDP genes are constitutively expressed at high levels or induced during desiccation in multiple tardigrade species. TDPs are required for tardigrade desiccation tolerance, and these genes are sufficient to increase desiccation tolerance when expressed in heterologous systems. TDPs form non-crystalline amorphous solids (vitrify) upon desiccation, and this vitrified state mirrors their protective capabilities. Our study identifies TDPs as functional mediators of tardigrade desiccation tolerance, expanding our knowledge of the roles and diversity of disordered proteins involved in stress tolerance

Optimizing multiple truck trips in a cooperative environment

Horizontal cooperation among truck carriers is the framework considered in the present paper. More specifically, the goal of this paper is to properly distribute the profits related to a set of carriers collaborating together for merging multiple trips. First, a mathematical model is set to maximize the total profit of the coalition of carriers. The solution of the resulting optimization problem provides the best way of satisfying the overall demand by maximizing the overall profit. The way in which the overall profit is, then, allocated to the different carriers, thus determining carrier individual profits, is analyzed by using five game theory (GT) allocation methods. The main contribution of this work stands in the application of GT for the profit allocation; in the literature the majority of work deals with cost distribution. Moreover, the methods here proposed are practical and easy to be used by real trucking companies and have been implemented for real life cases. Results obtained in terms of individual and overall profits are reported and discussed in this paper