Spatial clustering of interacting bugs: Levy flights versus Gaussian jumps

A biological competition model where the individuals of the same species perform a two-dimensional Markovian continuous-time random walk and undergo reproduction and death is studied. The competition is introduced through the assumption that the reproduction rate depends on the crowding in the neighborhood. The spatial dynamics corresponds either to normal diffusion characterized by Gaussian jumps or to superdiffusion characterized by L\'evy flights. It is observed that in both cases periodic patterns occur for appropriate parameters of the model, indicating that the general macroscopic collective behavior of the system is more strongly influenced by the competition for the resources than by the type of spatial dynamics. However, some differences arise that are discussed.Comment: This version incorporates in the text the correction published as an Erratum in Europhysics Letters (EPL) 95, 69902 (2011) [doi: 10.1209/0295-5075/95/69902

Letter to the editor: Are the North Atlantic Oscillation and the Southern Oscillation related in any time-scale?

International audienceThe North Atlantic Oscillation (NAO) and the Southern Oscillation (SO) are compared from the standpoint of a possible common temporal scale of oscillation. To do this a cross-spectrum of the temporal series of NAO and SO indices was determined, finding a significant common oscillation of 6-8 years. To assure this finding, both series were decomposed in their main oscillations using singular spectrum analysis (SSA). Resulting reconstructed series of 6-8 years oscillation were then cross-correlated without and with pre-whitened, the latter being significant. The main conclusion is a possible relationship between a common oscillation of 6-8 years' that represents about 20% of the SO variance and about 25% of the NAO variance

Medical Students’ Perception Towards the COVID-19 Pandemic in Mexico: Distance Learning, Assisting Hospitals, and Vaccination

Background: Mexico has been one of the most affected countries by the COVID-19 pandemic. Its health workers are playing a substantial role, but they are suffering from a high mortality rate, which highlights the need of vaccinating them before any other population. Medical interns have reduced their practices, some continue to assist clinical rotations without the protective equipment, and they are not being considered for vaccination. We wanted to determine the attitude of medical students and interns towards distance learning, assisting hospitals, and vaccination. Methods: We conducted a paired survey of a cohort of medical students who were evaluated twice, in June 2020 and in December 2020, using an online survey (32-online questions) to assess their perception of the pandemic. Results: We collected the response of 384 students in the summer period and 331 in the winter period; the majority were women from non-clinical semesters, and the median age of response was 21 years old (IQR 19 – 22). We found that the percentage of acceptance for vaccination was 95.6% in the summer and 93.7% in the winter, a remarkable acceptance in both periods. The percentage of students who manifested having someone close to them with symptoms suggestive of COVID-19 was 38.5% in the summer, showing an increase to 77.6% in the winter. Conclusion: We observed that medical students had a positive attitude towards vaccination and that the probable COVID-19 cases among them have increased in just a few months

Effect of the thermal treatment on the chemical components, sorption, and shrinkage properties of Tectona grandis juvenile wood

The effect of thermal treatment on the chemical components, equilibrium moisture content (EMC), and shrinkage of teak juvenile wood was studied. Heartwood and sapwood samples were thermally-treated at 180 ºC and 200 ºC. Extractive, Klason lignin, holocellulose, and α-cellulose contents, as well as pH on untreated and thermally-treated woods, were determined. The EMC was reached at five relative humidity (RH) levels using saturated salt solutions: 86 % (KCl), 76 % (NaCl), 58 % (NaBr), 33 % (MgCl2), and 0 % (P2O5). Linear and volumetric shrinkages were calculated for all EMCs. The ratio of sorption (S), coefficient of shrinkage (h), and fiber saturation point (FSP) were also determined. Thermally-treated wood exhibited lower holocellulose and α-cellulose contents than untreated wood and increased acidity due to degradation of the hemicelluloses. The thermal treatment reduced the EMC of heartwood and sapwood. However, sapwood was more sensitive to RH variations than heartwood regardless of the treatment. Thermally-treated woods had higher hygroscopic and dimensional stabilities, and lower FSP than untreated wood. The thermal treatment did not affect radial shrinkage of the heartwood between 33 % and 86 % RH. Heartwood was more sensitive to the effect of the thermal treatment on shrinkage and degradation of cell wall polymers compared to sapwood

Climate Change-induced Effects on Beach Degradation and Tourist Behaviour: A review of previous studies with potential in an island tourism context

This article conducts a qualitative meta-analysis of papers addressing the topic of climate change impacts on beach loss and degradation, and its relation to tourist behaviour (destination choice, willingness to re-visit, expenditure and willingness to pay). The main aim is to identify values that can be used in future research works in the context of island tourism. We found that the strong specialisation and fragmentation of data and methods limit the transferability potential of previous research analysing climate-induced effects on beaches and tourist behaviour. Researchers from different fields bring their own conceptual models which often address similar problems but use different lenses and measurement units. Among the available studies, the ones with usable potential in a value transfer context are related to willingness to pay for adaptation measures. Overall, findings confirm that a greater transparency in the methodologies used to elicit values and a multidisciplinary approach are needed to ensure a more sustainable use of the information in order to fill knowledge gaps that still hinder the study of climate change

A decision support system for modelling and implementing the supply network configuration and operations scheduling problem in the machine tool industry

[EN] This paper presents a decision support system to simultaneously solve the supply network configuration problem and the operations scheduling problem for the machine tool industry. A novel database structure, which is able to consider alternative operations and alternative bills of material, has been used. An algorithm for complete enumeration to determine all the feasible solutions using stroke graphs is introduced. A multiagent-based simulator evaluates the different key performance indicators that the supply network deals with for each alternative solution (e.g. workload, profits, delivery times, etc.) to determine that ‘satisficed’ by the collaborative decision-making among its members. A case study based on a Spanish company that assembles highly customised machines and tools in several European plants is considered. From the experiments results based on data linked to this industry, it will be demonstrated that the tool is potentially useful for stakeholders and for the central decision-maker to make decisions collaboratively in a multisite context caseWe thank the EWG-DSS and their four expert anonymous referees as well as the guest editorial board for their useful suggestions and criticism on earlier versions of this paper. The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement no. NMP2-SL-2009-229333 and has been partially supported by the Spanish Ministry of Science and Innovation within the 'Proyectos de Investigacion Fundamental No Orientada Programme' through Project 'CORSARI MAGIC DPI2010-18243'. Julien Maheut holds a VALi+d grant funded by the Regional Valencian Government (Ref. ACIF/2010/222).Maheut, JPD.; Besga, JM.; Uribetxebarria, J.; García Sabater, JP. (2014). A decision support system for modelling and implementing the supply network configuration and operations scheduling problem in the machine tool industry. Production Planning and Control. 25(8):679-697. https://doi.org/10.1080/09537287.2013.798087S67969725

Overlap Distribution of the Three-Dimensional Ising Model

We study the Parisi overlap probability density P_L(q) for the three-dimensional Ising ferromagnet by means of Monte Carlo (MC) simulations. At the critical point P_L(q) is peaked around q=0 in contrast with the double peaked magnetic probability density. We give particular attention to the tails of the overlap distribution at the critical point, which we control over up to 500 orders of magnitude by using the multi-overlap MC algorithm. Below the critical temperature interface tension estimates from the overlap probability density are given and their approach to the infinite volume limit appears to be smoother than for estimates from the magnetization.Comment: 7 pages, RevTex, 9 Postscript figure

Characterization of the annual regulation of reproductive and immune parameters on the testis of European sea bass

The European sea bass, Dicentrarchus labrax L., is a seasonal gonochoristic species, which males are generally mature during the second year of life. It has been demonstrated that cytokines and immune cells play a key role in the testicular development. This reproductive-immune interaction might be very important in the sea bass since several pathogens are able to colonize the gonad and persist in this tissue, altering further reproductive functions and spreading the disease. This study aims to investigate the reproductive cycle of one year European sea bass males by analyzing cell proliferation and apoptosis and expression profile of some reproductive and immune-related genes in the testis as well as the serum sex steroid levels. Our data demonstrate that in one year old European sea bass males, the testis undergoes the spermatogenesis process and that the reproductive and immune parameters analyzed varied during the reproductive cycle. In the testis, the highest proliferative rates were recorded at spermatogenesis stage, while the highest apoptotic rates were recorded at spawning stage. We have also analyzed, for the first time in European sea bass males, the serum levels of 17β-estradiol (E2) and dihydrotestosterone and the gene expression profile of the enzymes implied in their production, determining that at least E2 might be involved in the regulation of the reproductive cycle. Some immune relevant genes, including cytokines, lymphocyte receptors, anti-viral and antibacterial molecules were detected in the testis of naïve European sea bass specimens and their expression profile was related with the stages of the reproductive cycle, suggesting an important role for the defence of the reproductive tissues.Postprin