Mesonic Wavefunctions in the three-dimensional Gross-Neveu model

We present results from a numerical study of bound state wavefunctions in the (2+1)-dimensional Gross-Neveu model with staggered lattice fermions at both zero and nonzero temperature. Mesonic channels with varying quantum numbers are identified and analysed. In the strongly coupled chirally broken phase at T=0 the wavefunctions expose effects due to varying the interaction strength more effectively than straightforward spectroscopy. In the weakly coupled chirally restored phase information on fermion - antifermion scattering is recovered. In the hot chirally restored phase we find evidence for a screened interaction. The T=0 chirally symmetric phase is most readily distinguished from the symmetric phase at high T via the fermion dispersion relation.Comment: 18 page

Warming Can Boost Denitrification Disproportionately Due to Altered Oxygen Dynamics

Background: Global warming and the alteration of the global nitrogen cycle are major anthropogenic threats to the environment. Denitrification, the biological conversion of nitrate to gaseous nitrogen, removes a substantial fraction of the nitrogen from aquatic ecosystems, and can therefore help to reduce eutrophication effects. However, potential responses of denitrification to warming are poorly understood. Although several studies have reported increased denitrification rates with rising temperature, the impact of temperature on denitrification seems to vary widely between systems. Methodology/Principal Findings: We explored the effects of warming on denitrification rates using microcosm experiments, field measurements and a simple model approach. Our results suggest that a three degree temperature rise will double denitrification rates. By performing experiments at fixed oxygen concentrations as well as with oxygen concentrations varying freely with temperature, we demonstrate that this strong temperature dependence of denitrification can be explained by a systematic decrease of oxygen concentrations with rising temperature. Warming decreases oxygen concentrations due to reduced solubility, and more importantly, because respiration rates rise more steeply with temperature than photosynthesis. Conclusions/Significance: Our results show that denitrification rates in aquatic ecosystems are strongly temperature dependent, and that this is amplified by the temperature dependencies of photosynthesis and respiration. Our result

Domain wall fermions for planar physics

In 2+1 dimensions, Dirac fermions in reducible, i.e. four-component representations of the spinor algebra form the basis of many interesting model field theories and effective descriptions of condensed matter phenomena. This paper explores lattice formulations which preserve the global U(2N) symmetry present in the massless limit, and its breakdown to U(N)xU(N) implemented by three independent and parity-invariant fermion mass terms. I set out generalisations of the Ginsparg-Wilson relation, leading to a formulation of an overlap operator, and explore the remnants of the global symmetries which depart from the continuum form by terms of order of the lattice spacing. I also define a domain wall formulation in 2+1+1d, and present numerical evidence, in the form of bilinear condensate and meson correlator calculations in quenched non-compact QED using reformulations of all three mass terms, to show that U(2N) symmetry is recovered in the limit that the domain-wall separation L tends to infinity. The possibility that overlap and domain wall formulations of reducible fermions may coincide only in the continuum limit is discussed

The role of emotions on consumers’ satisfaction within the fitness context

Previous studies have suggested that consumption-related emotions are important to understand post-purchase reactions. This study examines the relationship between fitness consumers’ emotions and overall satisfaction. After an initial step of free-thought listing and content validity, followed by a pre-test, a survey was conducted among consumers of five different fitness centers (n=786). The questionnaire included measures to assess positive and negative emotions, as well as overall satisfaction with the fitness center. The results gathered through a structural equation model provide evidence that negative emotion experienced by consumers impacts negatively overall satisfaction, while positive emotion have a positive effect on overall satisfaction. These findings suggest managerial implications, such as the need to collect consumers’ perceptions of both tangible and intangible aspects of the services, listen costumers’ opinions in a regular basis, and provide regular training to staff members, in order to identify the triggers of positive emotions and contribute to increased levels of overall satisfaction. Guidelines for future research within the fitness context are also suggested.Estudos precedentes sugerem que as emoções relacionadas com o consumo são importantes para compreender as reações dos consumidores após a compra. Este estudo analisa a relação entre as emoções dos consumidores de fitness e satisfação global. Depois de uma etapa inicial de listagem de pensamento-livre e validade de conteúdo, seguido de um pré-teste, foi realizada uma pesquisa entre os consumidores de cinco centros de fitness diferentes (n = 786). O questionário incluiu medidas para avaliar as emoções positivas e negativas, bem como a satisfação global com o centro de fitness. Os resultados obtidos através de um modelo de equações estruturais forneceram evidências de que as emoções negativas vivenciadas pelos consumidores impactam negativamente a satisfação global, enquanto as emoções positivas têm um efeito positivo sobre a satisfação global. Estes resultados sugerem implicações para os gestores, tais como a necessidade de recolher informação sobre a perceção dos consumidores dos aspetos tangíveis e intangíveis dos serviços, ouvir regularmente as opiniões dos consumidores e facultar formação regular aos colaboradores. Isto permitirá identificar os aspetos que desencadeiam emoções positivas e contribuir para o aumento dos níveis de satisfação global. Orientações para futuras pesquisas no contexto de fitness também são sugeridas.Sin financiación0.185 SJR (2015) Q3, 1090/1779 Medicine (miscellaneous); Q4, 177/229 Health (social science), 112/128 Sports scienceUE

Iron Accumulation with Age, Oxidative Stress and Functional Decline

Identification of biological mediators in sarcopenia is pertinent to the development of targeted interventions to alleviate this condition. Iron is recognized as a potent pro-oxidant and a catalyst for the formation of reactive oxygen species in biological systems. It is well accepted that iron accumulates with senescence in several organs, but little is known about iron accumulation in muscle and how it may affect muscle function. In addition, it is unclear if interventions which reduced age-related loss of muscle quality, such as calorie restriction, impact iron accumulation. We investigated non-heme iron concentration, oxidative stress to nucleic acids in gastrocnemius muscle and key indices of sarcopenia (muscle mass and grip strength) in male Fischer 344 X Brown Norway rats fed ad libitum (AL) or a calorie restricted diet (60% of ad libitum food intake starting at 4 months of age) at 8, 18, 29 and 37 months of age. Total non-heme iron levels in the gastrocnemius muscle of AL rats increased progressively with age. Between 29 and 37 months of age, the non-heme iron concentration increased by approximately 200% in AL-fed rats. Most importantly, the levels of oxidized RNA in gastrocnemius muscle of AL rats were significantly increased as well. The striking age-associated increase in non-heme iron and oxidized RNA levels and decrease in sarcopenia indices were all attenuated in the calorie restriction (CR) rats. These findings strongly suggest that the age-related iron accumulation in muscle contributes to increased oxidative damage and sarcopenia, and that CR effectively attenuates these negative effects

Identifying a Window of Vulnerability during Fetal Development in a Maternal Iron Restriction Model

It is well acknowledged from observations in humans that iron deficiency during pregnancy can be associated with a number of developmental problems in the newborn and developing child. Due to the obvious limitations of human studies, the stage during gestation at which maternal iron deficiency causes an apparent impairment in the offspring remains elusive. In order to begin to understand the time window(s) during pregnancy that is/are especially susceptible to suboptimal iron levels, which may result in negative effects on the development of the fetus, we developed a rat model in which we were able to manipulate and monitor the dietary iron intake during specific stages of pregnancy and analyzed the developing fetuses. We established four different dietary-feeding protocols that were designed to render the fetuses iron deficient at different gestational stages. Based on a functional analysis that employed Auditory Brainstem Response measurements, we found that maternal iron restriction initiated prior to conception and during the first trimester were associated with profound changes in the developing fetus compared to iron restriction initiated later in pregnancy. We also showed that the presence of iron deficiency anemia, low body weight, and changes in core body temperature were not defining factors in the establishment of neural impairment in the rodent offspring