•New VRP with electric vehicles, considering partial recharges and several recharge technologies.•Constructive and improving heuristics embedded in a Simulated Annealing framework.•Computational ...study of the performance of the proposed algorithms on varying instances and particular problems.•Analysis of the impact of the different elements of the problem: geography, size, technologies, etc.
This paper presents several heuristics for a variation of the vehicle routing problem in which the transportation fleet is composed of electric vehicles with limited autonomy in need for recharge during their duties. In addition to the routing plan, the amount of energy recharged and the technology used must also be determined. Constructive and local search heuristics are proposed, which are exploited within a non deterministic Simulated Annealing framework. Extensive computational results on varying instances are reported, evaluating the performance of the proposed algorithms and analyzing the distinctive elements of the problem (size, geographical configuration, recharge stations, autonomy, technologies, etc.).
Numerical studies of the transition between Néel and valence bond solid phases in two-dimensional quantum antiferromagnets give strong evidence for the remarkable scenario of deconfined criticality, ...but display strong violations of finite-size scaling that are not yet understood. We show how to realize the universal physics of the Néel–valence-bond-solid (VBS) transition in a three-dimensional classical loop model (this model includes the subtle interference effect that suppresses hedgehog defects in the Néel order parameter). We use the loop model for simulations of unprecedentedly large systems (up to linear size L=512 ). Our results are compatible with a continuous transition at which both Néel and VBS order parameters are critical, and we do not see conventional signs of first-order behavior. However, we show that the scaling violations are stronger than previously realized and are incompatible with conventional finite-size scaling, even if allowance is made for a weakly or marginally irrelevant scaling variable. In particular, different approaches to determining the anomalous dimensions ηVBS and ηNéel yield very different results. The assumption of conventional finite-size scaling leads to estimates that drift to negative values at large sizes, in violation of the unitarity bounds. In contrast, the decay with distance of critical correlators on scales much smaller than system size is consistent with large positive anomalous dimensions. Barring an unexpected reversal in behavior at still larger sizes, this implies that the transition, if continuous, must show unconventional finite-size scaling, for example, from an additional dangerously irrelevant scaling variable. Another possibility is an anomalously weak first-order transition. By analyzing the renormalization group flows for the noncompact CPn−1 field theory (the n -component Abelian Higgs model) between two and four dimensions, we give the simplest scenario by which an anomalously weak first-order transition can arise without fine-tuning of the Hamiltonian.
Natural disasters are phenomenons which strike countries all around the world. Sometimes, either by the intensity of the phenomenon or the vulnerability of the country, help is requested from the ...rest of the world and relief organizations respond by delivering basic aid to those in need. Humanitarian logistics is a critical factor in managing relief operations and, in general, there is a lack of attention on the development of mathematical models and solution algorithms for strategic and tactical decisions in this area. We acknowledge that in humanitarian logistics traditional cost minimizing measures are not central, and postulate that other performance measures such as time of response, equity of the distribution or reliability and security of the operation routes become more relevant. In this paper several criteria for an aid distribution problem are proposed and a multi-criteria optimization model dealing with all these aspects is developed. This model is the core of a decision support system under development to assist organizations in charge of the distribution of humanitarian aid. Once the proposed criteria and the model are described, an illustrative case study based on the 2010 Haiti catastrophic earthquake is presented, showing the usefulness of the proposal.
The epithelial-to-mesenchymal transition (EMT) is a biological process in which a non-motile epithelial cell changes to a mesenchymal state with invasive capacities. However, the EMT program is ...involved in both physiological and pathological processes. Cancer-associated EMT is known to contribute to increase invasiveness and metastasis, resistance to therapies, and generation of cell populations with stem cell-like characteristics and therefore is deeply involved in tumor progression. This process is finely orchestrated by multiple signaling pathways and regulatory transcriptional networks. The hallmark of EMT is the loss of epithelial surface markers, mainly E-cadherin, and the acquisition of mesenchymal phenotype. These events can be mediated by EMT transcription factors which can cooperate with several enzymes to repress the E-cadherin expression and regulate EMT at the epigenetic and post-translational level. A growing body of evidence indicates that cancer cells can reside in various phenotypic states along the EMT spectrum, where cells can jointly retain epithelial traits with mesenchymal ones. This type of phenotypic plasticity endows cancer cells with tumor-initiating potential. The identification of the signaling pathways and modulators that lead to activation of EMT programs during these disease processes is providing new insights into the plasticity of cellular phenotypes and possible therapeutic interventions.
In this paper we describe a new type of subterranean habitat associated with dry watercourses in the Eastern Iberian Peninsula, the "Alluvial Mesovoid Shallow Substratum" (alluvial MSS). Historical ...observations and data from field sampling specially designed to study MSS fauna in the streambeds of temporary watercourses support the description of this new habitat. To conduct the sampling, 16 subterranean sampling devices were placed in a region of Eastern Spain. The traps were operated for 12 months and temperature and relative humidity data were recorded to characterise the habitat. A large number of species was captured, many of which belonged to the arthropod group, with marked hygrophilous, geophilic, lucifugous and mesothermal habits. In addition, there was also a substantial number of species showing markedly ripicolous traits. The results confirm that the network of spaces which forms in alluvial deposits of temporary watercourses merits the category of habitat, and here we propose the name of "alluvial MSS". The "alluvial MSS" may be covered or not by a layer of soil, is extremely damp, provides a buffer against above ground temperatures and is aphotic. In addition, compared to other types of MSS, it is a very unstable habitat. It is possible that the "alluvial MSS" may be found in other areas of the world with strongly seasonal climatic regimes, and could play an important role as a biogeographic corridor and as a refuge from climatic changes.
Beyond a critical disorder, two-dimensional (2D) superconductors become insulating. In this Superconductor-Insulator Transition (SIT), the nature of the insulator is still controversial. Here, we ...present an extensive experimental study on insulating Nb
Si
close to the SIT, as well as corresponding numerical simulations of the electrical conductivity. At low temperatures, we show that electronic transport is activated and dominated by charging energies. The sample thickness variation results in a large spread of activation temperatures, fine-tuned via disorder. We show numerically and experimentally that this originates from the localization length varying exponentially with thickness. At the lowest temperatures, there is an increase in activation energy related to the temperature at which this overactivated regime is observed. This relation, observed in many 2D systems shows that conduction is dominated by single charges that have to overcome the gap when entering superconducting grains.
Accessible summary
What is known on the subject?
Paediatric sleep problems are clinical conditions that often coexist with other mental health problems and meet criteria that warrant the ...implementation of screening procedures, including high prevalence, and significant clinical impact.
Researchers have designed the BEARS, a user‐friendly paediatric sleep screening tool that seems to increase the amount of sleep information recorded, as well as the likelihood of identifying sleep problems during routine health encounters. Nonetheless, there are no studies using the BEARS in Spanish‐speaking samples.
What this paper adds to existing knowledge?
Using a sample of children with mental health problems, this study provides support for the use of the Spanish version of the BEARS to identify the most common sleep problems seen in paediatric populations.
What are the implications for practice?
Considering how frequent sleep problems are, it is especially important for health professionals working with children in general, and with children with mental health problems in particular, to be aware of and be encouraged to use simple brief screening tools for paediatric sleep problems.
Objective
Research studies describe a high prevalence of sleep problems in children with mental health problems, up to 50%, and its role as a risk factor in the development of psychopathology. These often go unnoticed and are not evaluated in the clinical field. Our objective was to assess the concurrent validity of the BEARS, a brief paediatric sleep screening instrument, using the Children Sleep Habits Questionnaire (CSHQ) as the comparison instrument.
Methods
In this cross‐sectional descriptive study, the BEARS was applied by a registered nurse to a sample of parents of children aged 2–16 years (n = 60, 71.7% male) who attended a mental healthcare facility (located in Murcia, Spain) for the first time to receive a group psychoeducational intervention. The association between the information collected with the BEARS and scores on the related subscales of the CSHQ was assessed by Mann–Whitney U tests.
Results
Children who, according to the BEARS, had a sleep problem obtained scores on the CSHQ‐related subscales significantly higher than children who did not have a sleep problem (all Ps < 0.05).
Conclusion
Our results support the concurrent validity of the Spanish translation of the BEARS to detect sleep problems in paediatric nursing assessments. Further studies, with bigger and more heterogeneous samples, are warranted.
The aim of this study was to determine how distinctive patterns of unhelpful beliefs about sleep endorsed by insomnia patients relate to their presenting symptoms and treatment responses. A sample of ...281 primary insomnia sufferers completed items comprising the Dysfunctional Beliefs About Sleep scale (DBAS-16). Their resultant scores on the four DBAS-16 subscales were then subjected to a cluster analysis, which resulted in the identification of four distinctive age-matched subgroups. Two subgroups were characterized by pathologically elevated scores on at least two of the DBAS-16 subscales, whereas the other two subgroups had subscale scores that closely resembled those of a normative sample. Subsequent comparisons showed the insomnia subgroups differed in regard to their insomnia severity, use of prescribed medication for sleep, depression and anxiety symptoms, and daytime sleepiness. Furthermore, comparisons of treatment outcomes (i.e. analysis of change scores and normative comparisons) across clusters showed that the subgroups did not benefit equally from a standardized form of Cognitive-Behavioral Therapy (CBT) for insomnia. Findings demonstrate the contribution of specific sleep-related beliefs on presenting insomnia symptoms and suggest the potential usefulness of tailoring CBT protocols to match the needs of distinctive insomnia subtypes.
This research analyzes the effect of carbon pricing policies in transport electrification. It combines a heuristic algorithm to solve the Green Vehicle Routing Problem with Multiple Technologies and ...Partial Recharges with an economic Total Cost of Ownership model. The paper compares the performance of battery electric (BEV) and internal combustion vehicles (ICEV) for last mile delivery, using real data of Madrid (Spain). The results show that carbon pricing is scarcely effective when daily mileage is low (precisely when BEVs require incentives), and its effectivity increases as mileage increases (precisely when it is not so necessary to incentivize BEVs). Hence, carbon pricing is not an effective tool for promoting electric vehicles in the short term, and as a result, any political decision to fix CO
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prices must be adopted with a long-term view in mind. Specifically for the case of Spain, this research shows that current aids to BEVs are insufficient, with the exception of some regions like Madrid, which complement national subsidies with regional ones.
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