Interacting fermions and domain wall defects in 2+1 dimensions

We consider a Dirac field in 2+1 dimensions with a domain wall like defect in its mass, minimally coupled to a dynamical Abelian vector field. The mass of the fermionic field is assumed to have just one linear domain wall, which is externally fixed and unaffected by the dynamics. We show that, under some general conditions on the parameters, the localized zero modes predicted by the Callan and Harvey mechanism are stable under the electromagnetic interaction of the fermions

Métodos de alimentación alternativa para recién-nacidos prematuros

OBJECTIVE: To present a literature review about the use of glass/cup as an alternative method of feeding premature newborns and to identify if there is a consensus on its indication for this population. DATA SOURCE: A narrative review of the literature. Articles were selected from Medline, Lilacs, SciELO, and Cochrane databases, regardless of year, using the following specific key-words: feeding, premature newborn, breastfeeding, feeding methods. DATA SYNTHESIS: Although some studies showed that feeding premature and term newborns using the glass/cup is safe and efficient, most of them did not apply an objective evaluation of the swallowing to identify the effect of the method in this population. CONCLUSIONS: There is no consensus in the literature about feeding premature newborn infants by glass/cup. Controlled studies should be conducted in order to evaluate risks and benefits of alternative feeding methods in preterm newborn infants.OBJETIVO: Presentar revisión de literatura sobre el uso de vaso/taza como método alternativo de alimentación para recién-nacidos prematuros y verificar si hay consenso sobre su indicación para esta población. FUENTES DE DATOS: Revisión de literatura narrativa, habiendo sido seleccionados artículos en las bases de datos Medline, Lilacs, SciELO y Cochrane, independientemente del año, usando descriptores específicos: alimentación artificial, recién-nacido prematuro, lactancia materna, métodos de alimentación. SÍNTESIS DE LOS DATOS: Aunque algunos estudios afirmen que el método vaso/taza es eficaz y seguro para alimentar a recién-nacidos pre-término y a término, tales estudios no evalúan de modo objetivo el efecto del método sobre la deglución de estos pacientes. CONCLUSIONES: Se verificó que no hay consenso en la literatura respecto a la complementación de la alimentación de recién-nacidos prematuros mediante vaso/taza. Se debe realizar estudios controlados con la finalidad de rever riesgos y beneficios del uso de métodos alternativos en la alimentación del recién-nacido prematuro.OBJETIVO: Apresentar revisão de literatura sobre o uso do copo/xícara como método alternativo de alimentação para recém-nascidos prematuros e verificar se há consenso sobre sua indicação para essa população. FONTES DE DADOS: Revisão de literatura narrativa, tendo sido selecionados artigos nas bases de dados Medline, Lilacs, SciELO e Cochrane, independentemente do ano, usando descritores específicos: alimentação artificial, recém-nascido prematuro, aleitamento materno, métodos de alimentação. SÍNTESE DOS DADOS: Apesar de alguns estudos afirmarem que o método do copo/xícara é eficaz e seguro para alimentar recém-nascidos pré-termo e a termo, tais estudos não avaliam de forma objetiva o efeito do método sobre a deglutição desses pacientes. CONCLUSÕES: Verificou-se não haver consenso na literatura quanto à complementação da alimentação de recém-nascidos prematuros por meio do copo/xícara. Estudos controlados devem ser realizados com a finalidade de rever riscos e benefícios do uso de métodos alternativos na alimentação do recém-nascido prematuro.Universidade Federal de São Paulo (UNIFESP)Universidade Estadual Paulista Júlio de Mesquita Filho Departamento de FonoaudiologiaUNIFESPSciEL

Collapse and Revival in Holographic Quenches

We study holographic models related to global quantum quenches in finite size systems. The holographic set up describes naturally a CFT, which we consider on a circle and a sphere. The enhanced symmetry of the conformal group on the circle motivates us to compare the evolution in both cases. Depending on the initial conditions, the dual geometry exhibits oscillations that we holographically interpret as revivals of the initial field theory state. On the sphere, this only happens when the energy density created by the quench is small compared to the system size. However on the circle considerably larger energy densities are compatible with revivals. Two different timescales emerge in this latter case. A collapse time, when the system appears to have dephased, and the revival time, when after rephasing the initial state is partially recovered. The ratio of these two times depends upon the initial conditions in a similar way to what is observed in some experimental setups exhibiting collapse and revivals