The peremptory influence of a uniform background for trapping neutral fermions with an inversely linear potential

The problem of neutral fermions subject to an inversely linear potential is revisited. It is shown that an infinite set of bound-state solutions can be found on the condition that the fermion is embedded in an additional uniform background potential. An apparent paradox concerning the uncertainty principle is solved by introducing the concept of effective Compton wavelength

Bound states of bosons and fermions in a mixed vector-scalar coupling with unequal shapes for the potentials

The Klein-Gordon and the Dirac equations with vector and scalar potentials are investigated under a more general condition, $V_{v}+V_{s}= \mathrm{constant}$. These intrinsically relativistic and isospectral problems are solved in a case of squared hyperbolic potential functions and bound states for either particles or antiparticles are found. The eigenvalues and eigenfuntions are discussed in some detail and the effective Compton wavelength is revealed to be an important physical quantity. It is revealed that a boson is better localized than a fermion when they have the same mass and are subjected to the same potentials.Comment: 3 figure

Exploring a rheonomic system

A simple and illustrative rheonomic system is explored in the Lagrangian formalism. The difference between Jacobi's integral and energy is highlighted. A sharp contrast with remarks found in the literature is pointed out. The non-conservative system possess a Lagrangian not explicitly dependent on time and consequently there is a Jacobi's integral. The Lagrange undetermined multiplier method is used as a complement to obtain a few interesting conclusion

Different ventilatory responses to progressive maximal exercise test performed with either the arms or legs

OBJECTIVE: This study aimed to compare respiratory responses, focusing on the time-domain variability of ventilatory components during progressive cardiopulmonary exercise tests performed on cycle or arm ergometers. METHODS: The cardiopulmonary exercise tests were conducted on twelve healthy volunteers on either a cycle ergometer or an arm ergometer following a ramp protocol. The time-domain variabilities (the standard deviations and root mean squares of the successive differences) of the minute ventilation, tidal volume and respiratory rate were calculated and normalized to the number of breaths. RESULTS: There were no significant differences in the timing of breathing throughout the exercise when the cycle and arm ergometer measurements were compared. However, the arm exercise time-domain variabilities for the minute ventilation, tidal volume and respiratory rate were significantly greater than the equivalent values obtained during leg exercise. CONCLUSION: Although the type of exercise does not influence the timing of breathing when dynamic arm and leg exercises are compared, it does influence time-domain ventilatory variability of young, healthy individuals. The mechanisms that influence ventilatory variability during exercise remain to be studied

Risk of Hypothermia in a New Olympic Event: the 10-km Marathon Swim

INTRODUCTION: There are no available data addressing the potential clinical risks of open-water swimming competitions. OBJECTIVE: Address the risks of hypothermia and hypoglycemia during a 10-km open-water swimming competition in order to alert physicians to the potential dangers of this recently-introduced Olympic event. METHODS: This was an observational cross-sectional study, conducted during a 10-km open-water event (water temperature 21ºC). The highest ranked elite open-water swimmers in Brazil (7 men, 5 women; ages 21±7 years old) were submitted to anthropometrical measurements on the day before competition. All but one athlete took maltodextrine ad libitum during the competition. Core temperature and capillary glycemia data were obtained before and immediately after the race. RESULTS: Most athletes (83%) finished the race with mild to moderate hypothermia (core temperature <35ºC). The body temperature drop was more pronounced in female athletes (4.2±0.7ºC vs. male: 2.7±0.8ºC; p=0.040). When data from the athlete who did not take maltodextrine was excluded, capillary glycemia increased among athletes (pre 86.6±8.9 mg/dL; post 105.5±26.9 mg/dL; p=0.014). Time to complete the race was inversely related to pre- competition body temperature in men (r=-0.802; p=0.030), while it was inversely correlated with the change in capillary glycemia in women (r=-0.898; p=0.038). CONCLUSION: Hypothermia may occur during open-water swimming events even in elite athletes competing in relatively warm water. Thus, core temperature must be a chief concern of any physician during an open-water swim event. Capillary glycemia may have positive effects on performance. Further studies that include more athletes in a controlled setting are warranted

Theoretical and experimental study of the normal modes in a coupled two-dimensional system

[EN] In this work, the normal modes of a two-dimensional oscillating system have been studied from a theoretical and experimental point of view. The normal frequencies predicted by the Hessian matrix for a coupled two-dimensional particle system are compared to those obtained for a real system consisting of two oscillating smartphones coupled one to the other by springs. Experiments are performed on an air table in order to largely reduce the friction forces. The oscillation data are captured by the acceleration sensor of the smartphones and exported to file for further analysis. The experimental frequencies compare reasonably well with the theoretical predictions, specifically, within 1.7% of discrepancy.The authors would like to thank the Institute of Educational Sciences of the Universitat Politecnica de Val ` encia (Spain) ` for the support of the Teaching Innovation Groups MoMa and e-MACAF and for the financial support through the Project PIME 2015 B18. The authors would also like to thank Mrs Janet Anne Handcock for kindly revising the manuscript as a native English speaker.Giménez Valentín, MH.; Castro-Palacio, J.; Gómez-Tejedor, JA.; Velázquez, L.; Monsoriu Serra, JA. (2017). Theoretical and experimental study of the normal modes in a coupled two-dimensional system. Revista Mexicana de Fisica E. 63:100-106. http://hdl.handle.net/10251/99643S1001066

Contribución para la caracterización bioclimática del Norte de Portugal. La transición florística atlántico-mediterránea.

Contribución para la caracterización bioclimática del norte de Portugal. La transición florística atlántico-mediterránea. Este trabajo se incluye en la serie de trabajos ya iniciados por Crespí et al. (2001), con el objetivo de contribuir al conocimiento bioclimático del Norte de Portugal, a través de la información florística presente. En este sentido, y para proceder a una posible cartografia de las áreas biogeográficas naturales desde una perspectiva termopluviométrica, son ahora introducidos 39 nuevos táxones para la relación ya existente. Los táxones analizados en esta aportación son: Anthemis triumfetti f. flosculosa, Arnica montana subsp. atlantica, Aster aragonensis, Carduus bourgeanus, Carduus carpetanus, Carduus platypus subsp. platypus, Carduus platypus var. granatensis, Carduus pycnocephalus, Centaurea cyanus, Centaurea geresensi, Centaurea herminii subsp. herminii, Centaurea langeana, Centaurea rivularis, Centaurea triumfetti subsp. lingulata, Leucanthemopsis pallida subsp.flaveola, Leucanthemopsis pallida subsp. pulverulenta, Leuzea rhaponticoides, Phalacrocarpum hoffmannseggii, Santolina rosmarinifolia, Santolina semidentata, Arbutus unedo, Cistus ladanifer, Cistus laurifolius, Cistus populifolius, Cistus psilosepalus, Cistus salvifolius, Erica arborea, Erica australis, Erica ciliaris, Erica cinerea, Erica lusitanica, Erica scoparia, Erica tetralix, Erica umbellata, Halimium lasianthum subsp alyssoides, Halimium lasianthum subsp lasianthum, Halimium ocymoides, Halimium umbellatum subsp umbellatum, Halimium umbellatum subsp. viscosum. De modo a poder alcanzar los objetivos propuestos, se procede a la aplicación de una rutina programática multivariada, basada en un sistema de información geográfico (SIG), a partir del cual cada uno de los táxones estudiados es georeferenciado sobre cartografía ambiental (confeccionada y publicada por el Instituto para a Conservação da Natureza, del Ministerio del Ambiente portugués), comparándola después con las caracterizaciones fitoclimáticas de Franco (1994) y de Costa et al. (1998). Los resultados obtenidos confirman no sólo un acusado efecto gradual de transición entre el área de influencia bioclimática atlántica y la mediterránea, como además la existencia de una tendencia de comportamiento fitoclimático intermedio, no considerada hasta el momento en las caracterizaciones bioclimáticas ya publicadas.Approach on the climatic characterization for Northern of Portugal. The atlanticmediterranean floristic transition. Thirty-nine specific and infraspecific taxa with different occurrences in the continental portuguese area are referred in the present work. In the light of these behaviours, the climatic and geomorphological variability of the North of Portugal has been important environmental factors to explain the floristic diversity in this part of the country. In this case, the taxa analysed are: Anthemis triumfetti f. flosculosa, Arnica montana subsp. atlantica, Aster aragonensis, Carduus bourgeanus, Carduus carpetanus, Carduus platypus subsp. platypus, Carduus platypus var.granatensis, Carduus pycnocephalus, Centaurea cyanus, Centaurea geresensi, Centaurea herminii subsp. herminii, Centaurea langeana, Centaurea rivularis, Centaurea triumfetti subsp. lingulata, Leucanthemopsis pallida subsp. flaveola, Leucanthemopsis pallida subsp. pulverulenta, Leuzea rhaponticoides, Phalacrocarpum hoffmannseggii, Santolina rosmarinifolia, Santolina semidentata, Arbutus unedo, Cistus ladanifer, Cistus laurifolius, Cistus populifolius, Cistus psilosepalus, Cistus salvifolius, Erica arborea, Erica australis, Erica ciliaris, Erica cinerea, Erica lusitanica, Erica scoparia, Erica tetralix, Erica umbellata, Halimium lasianthum subsp alyssoides, Halimium lasianthum subsp lasianthum, Halimium ocymoides, Halimium umbellatum subsp umbellatum, Halimium umbellatum subsp. viscosum. Because of the appropriate management of the floristic richness, a multivariate statistic routine is applied on a Geographical Informatic System (GIS) the chorological, geomorphological and climatic characterization for each one are described in this paper. The geological substrate and the altitudinal classes are focused for the geomorphological approach, as well as two biogeographic classifications are used to correlate the occurrence of the taxa and their bioclimatic preferences. In the light of this analytical scheme, every taxa is geo-referenced upon an environmental cartography (elaborated by the Instituto para a Conservação da Natureza), compared with the Franco´s (1994) and Costa´s et al. (1998) phytoclimatic characterizations. The results obtained are pointing out the floristic progressive differentiation between the atlantic bioclimatic influence and the mediterranean one, as well as the existence of an intermediate bioclimatic tendency which had never been considered so far

Avifauna e uso da terra: o caso do Parque Natural de Montesinho

Apresenta-se uma possível utilização da informação dos atlas de avifauna como instrumentos de apoio à gestão de áreas de alta diversidade biológica. O atlas de avifauna do Parque Natural de Montesinho recolhe a informação relativa a um total de 119 espécies, de aves referenciadas, em 48 quadrículas de 5 por 5 quilómetros. A relação entre a avifauna e os sistemas de utilização da terra que a sustenta estimou-se por correlações canónicas (CCA - ter Braak, 1986). Uma análise de classificação (TWINSPAN- Hill, 1979) permitiu discriminar os sectores representativos do PNM. A amplitude de nicho das espécies em relação aos usos da terra, assim como a sua capacidade descritiva e discriminante, avaliam-se, mediante índices de informação (Shannon e Weaver, 1949). Os três eixos gerados pelas CCA avaliaram em 0,594, 0,689 e 0,633 a correlação (Kendall) da avifauna e os usos da terra considerados. Os seus resultados classificam o território do PNM em duas grandes unidades separadas pelo Rio Sabor, o sector ocidental evidencia gradientes climáticos e o oriental gradientes fisiográficos. São fundamentalmente passariformes residentes e biogeografia paleártica (Alauda arvensis, Pica pica, Passer montanus, etc.) as espécies mais envolvidas na dinâmica do território, apresentando os mais elevados valores de entropia. Os usos da terra apresentam distintas relações com o valor informativo das variáveis avifaunísticas. Destacam-se as relações positivas com os secadais, soutos e carvalhais, as neutras com as culturas de regadio e as negativas com os pinhais. A preponderância dos passeriformes residentes na discriminação do território destaca a escala de trabalho, para as quais o uso da terra têm uma importância acrescida na determinação do habitat dessas espécies. As relações com o uso da terra parecem manifestar uma adaptação da avifauna aos sistemas agrários tradicionais ( dos carvalhais aos lameiros e soutos), o que não ocorrerá em relação às formas mais modernas de utilização da terra (regadio e pinhais).Reitoria da Universidade de Coimbra, Fundação Calouste Gulbenkian, Fundação para a Ciência e Tecnologia, Fundação Luso-Americana para o Desenvolvimento, Câmara Municipal de Coimbra, Região de Turismo do Centro, Banco do Comércio e Indústria, SA, Cafés Delt

The Astounding World of Glycans from Giant Viruses

Viruses are a heterogeneous ensemble of entities, all sharing the need for a suitable host to replicate. They are extremely diverse, varying in morphology, size, nature, and complexity of their genomic content. Typically, viruses use host-encoded glycosyltransferases and glycosidases to add and remove sugar residues from their glycoproteins. Thus, the structure of the glycans on the viral proteins have, to date, typically been considered to mimick those of the host. However, the more recently discovered large and giant viruses differ from this paradigm. At least some of these viruses code for an (almost) autonomous glycosylation pathway. These viral genes include those that encode the production of activated sugars, glycosyltransferases, and other enzymes able to manipulate sugars at various levels. This review focuses on large and giant viruses that produce carbohydrate-processing enzymes. A brief description of those harboring these features at the genomic level will be discussed, followed by the achievements reached with regard to the elucidation of the glycan structures, the activity of the proteins able to manipulate sugars, and the organic synthesis of some of these virus-encoded glycans. During this progression, we will also comment on many of the challenging questions on this subject that remain to be addressed

STUDY OF AMORPHOUS GERMANIUM-NITROGEN ALLOYS THROUGH X-RAY PHOTOELECTRON AND AUGER ELECTRON SPECTROSCOPIES

In this work, experimentally determined values of electron spectroscopic shifts induced by nitrogen in Ge core levels of substoichiometric amorphous germanium-nitrogen (a-GeN) alloys are discussed and presented. X-ray photoelectron spectroscopy (XPS) and x-ray excited Auger electron spectroscopy (XAES) are employed to study the behavior of the Ge 3d and LMM spectra, respectively, and combined the corresponding XPS and Auger core levels shifts to determine Δα′, the modified Auger parameter shift, which is exempt from problems inherent in the interpretation of XPS and XAES shifts. It is demonstrated how one can use Δα′ to reliably estimate ΔnGe, the change in Ge valence charge in the alloys, and how one can calibrate XPS shifts of Si and Ge based alloys in terms of approximate values of ΔnGe