Causal explanation for observed superluminal behavior of microwave propagation in free space

In this paper we present a theoretical analysis of an experiment by Mugnai and collaborators where superluminal behavior was observed in the propagation of microwaves. We suggest that what was observed can be well approximated by the motion of a superluminal X wave. Furthermore the experimental results are also explained by the so called scissor effect which occurs with the convergence of pairs of signals coming from opposite points of an annular region of the mirror and forming an interference peak on the intersection axis traveling at superluminal speed. We clarify some misunderstandings concerning this kind of electromagnetic wave propagation in vacuum.Comment: 9 pages, 3 figures, accepted for publication in Physics Letters

Non-destructive soluble solids content determination for ‘Rocha’ Pear Based on VIS-SWNIR spectroscopy under ‘Real World’ sorting facility conditions

In this paper we report a method to determine the soluble solids content (SSC) of 'Rocha' pear (Pyrus communis L. cv. Rocha) based on their short-wave NIR reflectance spectra (500-1100 nm) measured in conditions similar to those found in packinghouse fruit sorting facilities. We obtained 3300 reflectance spectra from pears acquired from different lots, producers and with diverse storage times and ripening stages. The macroscopic properties of the pears, such as size, temperature and SSC were measured under controlled laboratory conditions. For the spectral analysis, we implemented a computational pipeline that incorporates multiple pre-processing techniques including a feature selection procedure, various multivariate regression models and three different validation strategies. This benchmark allowed us to find the best model/preproccesing procedure for SSC prediction from our data. From the several calibration models tested, we have found that Support Vector Machines provides the best predictions metrics with an RMSEP of around 0.82 ∘ Brix and 1.09 ∘ Brix for internal and external validation strategies respectively. The latter validation was implemented to assess the prediction accuracy of this calibration method under more 'real world-like' conditions. We also show that incorporating information about the fruit temperature and size to the calibration models improves SSC predictability. Our results indicate that the methodology presented here could be implemented in existing packinghouse facilities for single fruit SSC characterization.Funding Agency CEOT strategic project UID/Multi/00631/2019 project OtiCalFrut ALG-01-0247-FEDER-033652 Ideias em Caixa 2010, CAIXA GERAL DE DEPOSITOS Fundacao para a Ciencia e a Tecnologia (Ciencia)info:eu-repo/semantics/publishedVersio

Exploring Sustainable Supply Chain Management: A Social Network Perspective

Purpose The implementation of sustainable supply chain management (SCM) calls for an acknowledgement of uncertainty inherent in complex environment. Confucianist society forms social networks in Confucianist society, called guanxi networks, influence economic behaviours and business practices in the workplace. The purpose of this study is to explore how these social networks influence the implementation of sustainable SCM. In doing so, this study aims to critically investigate the constructs of guanxi networks, their impact on flow of supply chain capital and how this leverages the implementation of sustainable SCM. Design/methodology/approach Two systematic literature reviews are conducted to understand the constructs of social networks in Confucianist culture and their impacts on the flow of supply chain capitals. The reviews also analyse evidence related to the economic, social and environmental practices to reveal the current state of the literature and research gaps. Propositions and a framework are developed to support future research in this area. Findings The constructs of ganqing, renqing, xinren and mianzi in guanxi networks have expanded the contexts of social networks in Western literature. Guanxi networks increase the flow of supply chain capital and generate trust between players, thus enhancing capabilities to implement sustainable SCM. Guanxi networks also create the mechanism of network governance with which to increase sustainable SCM implementation under the institutional logics of sustainability. Research limitations/implications The conceptual framework and justification are based on the reviews of current studies in the field. Future empirical study is encouraged to test the propositions, both in Confucianist culture and other countries with culture of social networks. Originality/value Social networks are socially constructed concepts. The constructs of guanxi networks revealed in this study have developed the knowledge of Western-based social network theory. Besides, arguments from a social network perspective provide an alternative answer to explain increased behavioural commitment and companies’ investment in sustainable SCM. This study helps practitioners understand the logic of this social norm and to use it to maximise their operation outputs, including sustainable SCM implementation

Separation of enantiomers of 1a,2,7,7a-tetrahydro-3-methoxynaphtha-(2,3b)-oxirane by liquid chromatography: laboratory-scale elution chromatography and modelling of simulated moving bed

The separation of enantiomers of la,2,7,7a-tetrahydro-3-methoxynaphtha-(2,3b)-oxirane (Sandoz epoxide) on cellulose triacetate HPLC columns was investigated on the laboratory scale. The performance of the columns was calculated by HEPT measurements and the slopes of the adsorption equilibrium isotherms and effective diffusivities were calculated from elution chromatographic experiments. Multi-component adsorption equilibrium isotherms were calculated from single isotherms by using the ideal adsorbed solution (IAS) model. Simulation of continuous chromatographic separation of the racemic mixture of Sandoz epoxide in a simulated moving bed was carried out and the effect of mass transfer coefficient on process performance was analysed

The relationship between motor competence and health-related fitness in children and adolescents

Background and aims In the last twenty years, there has been increasing evidence that Motor Competence (MC) is vital for developing an active and healthy lifestyle. This study analyses the associations between motor competence and its components, with health-related fitness (HRF). Methods A random sample of 546 children (278 males, mean = 10.77 years) divided into four age groups (7?8; 9?10; 11?12; 13?14 years old) was evaluated. A quantitative MC instrument (evaluating stability, locomotor and manipulative skills), a maximal multistage 20-m shuttle-run test and the handgrip test, height and BMI were used in the analyses. Pearson correlations and standard regression modelling were performed to explore the associations between variables. Results Moderate to strong significant correlations (0.49 < r < 0.73) were found between MC and HRF, for both sexes, and correlation values were stable across the age groups. The MC model explained 74% of the HRF variance, with the locomotor component being the highest predictor for the entire sample (? = .302; p < .001). Gender-related differences were found when boys and girls were analysed at each age group. Locomotor MC for girls was the most consistent significant predictor of HRF across all age groups (0.47 < ? < 0.65; all p .001). For boys, significant predictors were locomotor and manipulative MC (0.21 < ? < 0.49; all p < .05) in the two younger age groups (7?8 and 9?10 years) and stability (0.50 < ? < 0.54; all p .001) for the older two age groups (11?12 and 13?14 years). Conclusion These results support the idea that: (1) the relationship between overall MC and HRF is strong and stable across childhood and early adolescence; (2) when accounting for the different MC components, boys and girls show different relationship patterns with HFR across age.4811-99FE-2ECD | Luis Paulo Rodriguesinfo:eu-repo/semantics/publishedVersio

Correlates of children's physical activity during the COVID-19 confinement in Portugal

Objectives: The aim of the study was to understand the role of household variables on the percentage of physical activity (%PA) during the coronavirus disease 2019 (COVID-19) confinement in Portugal. Study design: A cross-sectional study design using an anonymous online survey was launched to assess how Portuguese families with children aged younger than 13 years adjusted their daily routines to the confinement. Methods: Separate analyses of variance were performed to investigate how factors such as the number of children, age, sex, the housing characteristics, and the adults' job situation can affect the percentage of time for PA (%PA). Results: Findings, based on data from 2159 children, indicate that (1) boys and girls did not differ in the %PA on any of the age-groups; (2) children with an outdoor space and who had other children in the household were significantly more active (P < .001); (3) children from families with all adults working from home showed lower levels of %PA; and (4) being younger, having a big outdoor space, having other children in the household, and having at least one adult free from working from home were significant positive predictors of children's %PA, explaining 21% of the overall variance. Conclusion: Time allocated for PA during this period is reduced compared with what is usually reported on normal days. It is necessary to find strategies to increase children's PA, especially in families in which both parents are working and have no outdoor space.4811-99FE-2ECD | Luis Paulo RodriguesN/

an exploratory study

Background: The association between obesity and physical inactivity strongly and independently predict overall obesity in young adulthood. Physical inactivity and increasing obesity in our society is multifaceted, but on key factor to promote physical activity is motor competence (MC). Purpose: This study aimed to analyse a physically active group of young adults by investigating the correlations between MC, adiposity and body mineral density by using dual X-ray absorptiometry (DXA). Methods: Forty-four young men (22,1 ? years; 69,0 ? kg; 173,7 ? meters) and 21 young women (20,2 ? years; 63,8 ? kg; 169,6 ? meters) participated in this study and completed anthropometrics; DXA; Motor Competence assessment battery that comprise two tests for each of the three constructs: locomotor, manipulative and stability. Descriptive statistics were considered and Spearman's correlation test to examine the association between MC scores and DXA results. The Mann-Whitney test was used to compare males to females for p < 0,05. Results: Motor Competence (MC) variables and body composition in female revealed significant associations only between shuttle run and total fat (r = ?0,648). In males, demonstrate several positive statistically asso ciations with MC Stability and Locomotor tasks and constructs (p < 0,05). Conclusions: In very active young adults, MC positive influences weight status, particularly in locomotor and stability tasks.4811-99FE-2ECD | Luis Paulo RodriguesN/

a narrative review

Through development, a child?s varied movement contexts provide different opportunities or affordances for action that are fundamental to promoting motor competence. Although home is the primary environment for infants, as children age, school and sport environments gain importance. Studies focusing on affordances for motor behavior in children have mainly addressed the home microsystem, providing an incomplete picture of affordances across different settings, particularly later in development. Here, we undertook a narrative literature review of various affordances for children?s motor development. This review revealed that prior studies of school and sports contexts have not specifically focused on those environmental properties that promote or hinder motor learning opportunities, meaning that future research should assess these relationships through manipulations of environmental features in these different microsystems.4811-99FE-2ECD | Luis Paulo RodriguesN/

a four-year follow-up study in portuguese children

Children?s motor competence (MC) was negatively affected by the COVID-19 pandemic; however, possible chronic effects have not been studied. Therefore, the aim of this study was to examine the possible impact of the forced lack of physical activity (PA) during the COVID-19 lockdown on children?s MC two years later. The motor competence of sixty-seven healthy children (7.4?12.2 years old) was assessed using the Motor Competence Assessment (MCA). All participants completed the MCA tests at two different moments (before and after the COVID-19 lockdown), four years apart. The mean values after the COVID-19 lockdown for all participants on the subscales and on the Total MCA are lower, but no significant changes were found when controlling for gender and age (p > 0.05 in all analyses). However, a significant decrease was found in the Locomotor subscale in boys (p = 0.003). After dividing the participants into three age groups, the youngest also suffered a decrease in the Locomotor subscale (p < 0.001) and their Total MCA (p = 0.04). In addition, those participants who had a higher MC at baseline decreased their scores for the Locomotor (p < 0.001) and Manipulative (p < 0.001) subscales, and for the Total MCA (p < 0.001). In conclusion, the younger children and the more motor proficient did not fully recover from the negative effects of the pandemic lockdown after two years.4811-99FE-2ECD | Luis Paulo RodriguesN/

B∗B∗ρB^{\ast}B^{\ast}\rho vertex from QCD sum rules

The form factors and the coupling constants in the $B^{\ast}B^{\ast}\rho$ vertex are evaluated in the framework of three-point QCD sum rules. The correlation functions responsible for the form factors are evaluated considering contributions of both $B^{\ast}$ and $\rho$ mesons as off-shell states. The obtained numerical results for the coupling constants are in agreement with light-cone QCD sum rules calculations.Comment: 18 pages, 11 figures, to appear on Phys. Lett.