Towards a Collision-Free WLAN: Dynamic Parameter Adjustment in CSMA/E2CA

Carrier Sense Multiple Access with Enhanced Collision Avoidance (CSMA/ECA) is a distributed MAC protocol that allows collision-free access to the medium in WLAN. The only difference between CSMA/ECA and the well-known CSMA/CA is that the former uses a deterministic backoff after successful transmissions. Collision-free operation is reached after a transient state during which some collisions may occur. This article shows that the duration of the transient state can be shortened by appropriately setting the contention parameters. Standard absorbing Markov Chain theory can be used to describe the behaviour of the system in the transient state and to predict the expected number of slots to reach the collision-free operation. The article also introduces CSMA/E2CA, in which a deterministic backoff is used two consecutive times after a successful transmission. CSMA/E2CA converges quicker to collision-free operation and delivers higher performance than CSMA/CA in harsh wireless scenarios with high frame error rates. To achieve collision-free operations when the number of contenders is large, it may be necessary to dynamically adjust the contention parameter. The last part of the article suggests an approach for such parameter adjustment which is validated by simulation results

Diseño y optimización de sistemas de transformación y conservación de naranja variedad “Canoneta” de la Serra Nord mallorquina para obtención de naranja IV gama

Este trabajo muestra el efecto de diferentes tipos de procesado sobre la vida útil de naranjas mínimamente procesadas de la variedad “Canoneta”. Las naranjas peladas de manera mecánica o semimanual fueron envasadas en dos atmósferas (vacío parcial y 20% CO2+ 80% N2) y se almacenaron durante 10 días a 4ºC y a 8ºC. Los análisis sensoriales, microbiológicos y físicoquímicos identificaron el pelado semi-manual como el menos idóneo de los métodos de pelado y se estableció 7 días como la vida útil máxima para un producto aceptable desde el punto de vista sensorial

Impact of climate change on berthing areas in ports of the Balearic Islands: adaptation measures

Climate change generates impacts on coastal areas due to sea-level rise and potential modifications in wave and storm surge patterns. Since harbours are located in littoral areas, they will experience different impacts associated to such processes. In this paper, the effects of climate change on port berthing areas in terms of operability are quantified. The study is focused on the ports of the Balearic Islands (Western Mediterranean Sea) and analyses the loss of operability due to the reduction of freeboard in berthing structures and the potential variation in agitation within these harbours during the 21st century, considering two different climate scenarios (RCP4.5 and RCP8.5) and two-time horizons (2045 and 2100). In addition, adaptation measures to address such impacts are proposed and their cost estimated. The results indicate that climate change will not generate significant changes in wave agitation due to negligible variations in wave patterns under future scenarios. On the contrary, sea-level rise will cause huge increases of inoperability for berthing structures due to insufficient freeboard: 10.5% under RCP4.5 or 20.5% under RCP8.5 in 2045, increasing to 57.1% (RCP4.5) and even 83.2% (RCP8.5) in 2100.This study was supported by PIMA ADAPTA-Balears Project funded by Conselleria de Transició Energética, Sectors Productius i Memòria Democràtica and Conselleria de Mobilitat i Habitatge, Govern Balear, and by the project PLEC2021-007810 funded by MCIN/AEI/10.13039/501100011033 and by the European Union “Next Generation EU”/PRTR”.Peer ReviewedPostprint (published version

Bulk viscosity in a cold CFL superfluid

We compute one of the bulk viscosity coefficients of cold CFL quark matter in the temperature regime where the contribution of mesons, quarks and gluons to transport phenomena is Boltzmann suppressed. In that regime dissipation occurs due to collisions of superfluid phonons, the Goldstone modes associated to the spontaneous breaking of baryon symmetry. We first review the hydrodynamics of relativistic superfluids, and remind that there are at least three bulk viscosity coefficients in these systems. We then compute the bulk viscosity coefficient associated to the normal fluid component of the superfluid. In our analysis we use Son's effective field theory for the superfluid phonon, amended to include scale breaking effects proportional to the square of the strange quark mass m_s. We compute the bulk viscosity at leading order in the scale breaking parameter, and find that it is dominated by collinear splitting and joining processes. The resulting transport coefficient is zeta=0.011 m_s^4/T, growing at low temperature T until the phonon fluid description stops making sense. Our results are relevant to study the rotational properties of a compact star formed by CFL quark matter.Comment: 19 pages, 2 figures; one reference added, version to be published in JCA

Impact of obstructive sleep apnea on the levels of placental growth factor (PlGF) and their value for predicting short-term adverse outcomes in patients with acute coronary syndrome

Background Placental growth factor (PlGF) induces angiogenesis and promotes tissue repair, and plasma PlGF levels change markedly during acute myocardial infarction (AMI). Currently, the impact of obstructive sleep apnea (OSA) in patients with AMI is a subject of debate. Our objective was to evaluate the relationships between PlGF levels and both the severity of acute coronary syndrome (ACS) and short-term outcomes after ACS in patients with and without OSA. Methods A total of 538 consecutive patients (312 OSA patients and 226 controls) admitted for ACS were included in this study. All patients underwent polygraphy in the first 72 hours after hospital admission. The severity of disease and short-term prognoses were evaluated during the hospitalization period. Plasma PlGF levels were measured using an electrochemiluminescence immunoassay. Results Patients with OSA were significantly older and more frequently hypertensive and had higher BMIs than those without OSA. After adjusting for age, smoking status, BMI and hypertension, PlGF levels were significantly elevated in patients with OSA compared with patients without OSA (19.9 pg/mL, interquartile range: 16.6–24.5 pg/mL; 18.5 pg/mL, interquartile range: 14.7–22.7 pg/mL; p<0.001), and a higher apnea-hypopnea index (AHI) was associated with higher PlGF concentrations (p<0.003). Patients with higher levels of PlGF had also an increased odds ratio for the presence of 3 or more diseased vessels and for a Killip score>1, even after adjustment. Conclusions The results of this study show that in patients with ACS, elevated plasma levels of PlGF are associated with the presence of OSA and with adverse outcomes during short-term followup. Trial Registration ClinicalTrials.gov NCT0133508

Hydroxychloroquine is associated with a lower risk of polyautoimmunity: data from the RELESSER Registry

Objectives. This article estimates the frequency of polyautoimmunity and associated factors in a large retrospective cohort of patients with SLE. Methods. RELESSER (Spanish Society of Rheumatology Lupus Registry) is a nationwide multicentre, hospital-based registry of SLE patients. This is a cross-sectional study. The main variable was polyautoimmunity, which was defined as the co-occurrence of SLE and another autoimmune disease, such as autoimmune thyroiditis, RA, scleroderma, inflammatory myopathy and MCTD. We also recorded the presence of multiple autoimmune syndrome, secondary SS, secondary APS and a family history of autoimmune disease. Multiple logistic regression analysis was performed to investigate possible risk factors for polyautoimmunity. Results. Of the 3679 patients who fulfilled the criteria for SLE, 502 (13.6%) had polyautoimmunity. The most frequent types were autoimmune thyroiditis (7.9%), other systemic autoimmune diseases (6.2%), secondary SS (14.1%) and secondary APS (13.7%). Multiple autoimmune syndrome accounted for 10.2% of all cases of polyautoimmunity. A family history was recorded in 11.8%. According to the multivariate analysis, the factors associated with polyautoimmunity were female sex [odds ratio (95% CI), 1.72 (1.07, 2.72)], RP [1.63 (1.29, 2.05)], interstitial lung disease [3.35 (1.84, 6.01)], Jaccoud arthropathy [1.92 (1.40, 2.63)], anti-Ro/SSA and/or anti-La/SSB autoantibodies [2.03 (1.55, 2.67)], anti-RNP antibodies [1.48 (1.16, 1.90)], MTX [1.67 (1.26, 2.18)] and antimalarial drugs [0.50 (0.38, 0.67)]. Conclusion. Patients with SLE frequently present polyautoimmunity. We observed clinical and analytical characteristics associated with polyautoimmunity. Our finding that antimalarial drugs protected against polyautoimmunity should be verified in future studies

Rising rural body-mass index is the main driver of the global obesity epidemic in adults

Body-mass index (BMI) has increased steadily in most countries in parallel with a rise in the proportion of the population who live in cities(.)(1,2) This has led to a widely reported view that urbanization is one of the most important drivers of the global rise in obesity(3-6). Here we use 2,009 population-based studies, with measurements of height and weight in more than 112 million adults, to report national, regional and global trends in mean BMI segregated by place of residence (a rural or urban area) from 1985 to 2017. We show that, contrary to the dominant paradigm, more than 55% of the global rise in mean BMI from 1985 to 2017-and more than 80% in some low- and middle-income regions-was due to increases in BMI in rural areas. This large contribution stems from the fact that, with the exception of women in sub-Saharan Africa, BMI is increasing at the same rate or faster in rural areas than in cities in low- and middle-income regions. These trends have in turn resulted in a closing-and in some countries reversal-of the gap in BMI between urban and rural areas in low- and middle-income countries, especially for women. In high-income and industrialized countries, we noted a persistently higher rural BMI, especially for women. There is an urgent need for an integrated approach to rural nutrition that enhances financial and physical access to healthy foods, to avoid replacing the rural undernutrition disadvantage in poor countries with a more general malnutrition disadvantage that entails excessive consumption of low-quality calories.Peer reviewe

Height and body-mass index trajectories of school-aged children and adolescents from 1985 to 2019 in 200 countries and territories: a pooled analysis of 2181 population-based studies with 65 million participants

Summary Background Comparable global data on health and nutrition of school-aged children and adolescents are scarce. We aimed to estimate age trajectories and time trends in mean height and mean body-mass index (BMI), which measures weight gain beyond what is expected from height gain, for school-aged children and adolescents. Methods For this pooled analysis, we used a database of cardiometabolic risk factors collated by the Non-Communicable Disease Risk Factor Collaboration. We applied a Bayesian hierarchical model to estimate trends from 1985 to 2019 in mean height and mean BMI in 1-year age groups for ages 5–19 years. The model allowed for non-linear changes over time in mean height and mean BMI and for non-linear changes with age of children and adolescents, including periods of rapid growth during adolescence. Findings We pooled data from 2181 population-based studies, with measurements of height and weight in 65 million participants in 200 countries and territories. In 2019, we estimated a difference of 20 cm or higher in mean height of 19-year-old adolescents between countries with the tallest populations (the Netherlands, Montenegro, Estonia, and Bosnia and Herzegovina for boys; and the Netherlands, Montenegro, Denmark, and Iceland for girls) and those with the shortest populations (Timor-Leste, Laos, Solomon Islands, and Papua New Guinea for boys; and Guatemala, Bangladesh, Nepal, and Timor-Leste for girls). In the same year, the difference between the highest mean BMI (in Pacific island countries, Kuwait, Bahrain, The Bahamas, Chile, the USA, and New Zealand for both boys and girls and in South Africa for girls) and lowest mean BMI (in India, Bangladesh, Timor-Leste, Ethiopia, and Chad for boys and girls; and in Japan and Romania for girls) was approximately 9–10 kg/m2. In some countries, children aged 5 years started with healthier height or BMI than the global median and, in some cases, as healthy as the best performing countries, but they became progressively less healthy compared with their comparators as they grew older by not growing as tall (eg, boys in Austria and Barbados, and girls in Belgium and Puerto Rico) or gaining too much weight for their height (eg, girls and boys in Kuwait, Bahrain, Fiji, Jamaica, and Mexico; and girls in South Africa and New Zealand). In other countries, growing children overtook the height of their comparators (eg, Latvia, Czech Republic, Morocco, and Iran) or curbed their weight gain (eg, Italy, France, and Croatia) in late childhood and adolescence. When changes in both height and BMI were considered, girls in South Korea, Vietnam, Saudi Arabia, Turkey, and some central Asian countries (eg, Armenia and Azerbaijan), and boys in central and western Europe (eg, Portugal, Denmark, Poland, and Montenegro) had the healthiest changes in anthropometric status over the past 3·5 decades because, compared with children and adolescents in other countries, they had a much larger gain in height than they did in BMI. The unhealthiest changes—gaining too little height, too much weight for their height compared with children in other countries, or both—occurred in many countries in sub-Saharan Africa, New Zealand, and the USA for boys and girls; in Malaysia and some Pacific island nations for boys; and in Mexico for girls. Interpretation The height and BMI trajectories over age and time of school-aged children and adolescents are highly variable across countries, which indicates heterogeneous nutritional quality and lifelong health advantages and risks