Neutrino Masses, Grand Unification, and Baryon Number Violation

If grand unification is real, searches for baryon-number violation should be included on the list of observables that may reveal information regarding the origin of neutrino masses. Making use of an effective-operator approach and assuming that nature is SU(5) invariant at very short distances, we estimate the consequences of different scenarios that lead to light Majorana neutrinos for low-energy phenomena that violate baryon number minus lepton number (B-L) by two (or more) units, including neutron-antineutron oscillations and B-L violating nucleon decays. We find that, among all possible effective theories of lepton-number violation that lead to nonzero neutrino masses, only a subset is, broadly speaking, consistent with grand unification.Comment: 12 pages, 1 figure. Improved discussion, references added, results unchange

Astrocytic Ephrin-B1 Regulates Synapse Remodeling Following Traumatic Brain Injury.

Traumatic brain injury (TBI) can result in tissue alterations distant from the site of the initial injury, which can trigger pathological changes within hippocampal circuits and are thought to contribute to long-term cognitive and neuropsychological impairments. However, our understanding of secondary injury mechanisms is limited. Astrocytes play an important role in brain repair after injury and astrocyte-mediated mechanisms that are implicated in synapse development are likely important in injury-induced synapse remodeling. Our studies suggest a new role of ephrin-B1, which is known to regulate synapse development in neurons, in astrocyte-mediated synapse remodeling following TBI. Indeed, we observed a transient upregulation of ephrin-B1 immunoreactivity in hippocampal astrocytes following moderate controlled cortical impact model of TBI. The upregulation of ephrin-B1 levels in hippocampal astrocytes coincided with a decline in the number of vGlut1-positive glutamatergic input to CA1 neurons at 3 days post injury even in the absence of hippocampal neuron loss. In contrast, tamoxifen-induced ablation of ephrin-B1 from adult astrocytes in ephrin-B1(loxP/y)ERT2-Cre(GFAP) mice accelerated the recovery of vGlut1-positive glutamatergic input to CA1 neurons after TBI. Finally, our studies suggest that astrocytic ephrin-B1 may play an active role in injury-induced synapse remodeling through the activation of STAT3-mediated signaling in astrocytes. TBI-induced upregulation of STAT3 phosphorylation within the hippocampus was suppressed by astrocyte-specific ablation of ephrin-B1 in vivo, whereas the activation of ephrin-B1 in astrocytes triggered an increase in STAT3 phosphorylation in vitro. Thus, regulation of ephrin-B1 signaling in astrocytes may provide new therapeutic opportunities to aid functional recovery after TBI

Efectividad de la fotocoagulación con láser comparado con bevacizumab en el tratamiento de retinopatía de la prematuridad en recién nacidos con peso menor de 2000 gramos atendidos en el Hospital Belén de Trujillo, enero 2009 - diciembre 2015

Objetivo: Determinar la Efectividad de la fotocoagulación con láser comparado con bevacizumab en el tratamiento de retinopatía de la prematuridad en recién nacidos con peso menor de 2000 gramos atendidos en el Hospital Belén de Trujillo, Enero 2009 – Diciembre 2015 Material y métodos: Estudio analítico, observacional, de cohortes retrospectivo en 52 recién nacidos con peso menor de 2000 gramos con retinopatía de la prematuridad que se dividieron en 2 grupos: fotocoagulación con láser o bevacizumab. Resultados: No se apreciaron diferencias significativas entre los grupos de estudio en relación con la edad gestacional al nacimiento, la edad al momento del tratamiento, el peso del recién nacido, características neonatales y comorbilidades (p>0.05). El tratamiento con bevacizumab ofrece mayor seguridad que la fotocoagulación con láser en pacientes con retinopatía de la prematuridad en recién nacidos con peso menor de 2000 gramos (p<0.05). Conclusiones: La efectividad del bevacizumab es similar a la efectividad de la fotocoagulación con láser en el tratamiento de retinopatía de la prematuridad en recién nacidos con peso menor de 2000 gramos.Objective: To determine the effectiveness of laser photocoagulation compared to bevacizumab in the treatment of retinopathy of prematurity in newborns weighing less than 2000 grams treated at Hospital Belén de Trujillo, January 2009 - December 2015 Material and methods: An observational, retrospective cohort study of 52 newborns weighing less than 2000 grams with retinopathy of prematurity who were divided into 2 groups: laser photocoagulation or bevacizumab. Results: There were no significant differences between gestational age at birth, age at treatment, newborn weight, neonatal characteristics and comorbidities (p> 0.05). Bevacizumab treatment offers greater safety than laser photocoagulation in patients with retinopathy of prematurity in newborns weighing less than 2000 grams (p <0.05). Conclusions: The effectiveness of bevacizumab is similar to the effectiveness of laser photocoagulation in the treatment of retinopathy of prematurity in newborns weighing less than 2000 grams.Tesi

Does Globalization Affect Top Income Inequality?

We reexamine in this paper the role of globalization on top income shares (five classes from top 0.1% to top 10% of the income distribution) for a sample of 15 economies over the period 1970–2004. We investigate financial globalization measures that complement trade openness. Our system GMM (SGMM) estimations allow for a robust treatment of the endogeneity between income concentration and GDP per capita (as well as with taxation or government size). We find two interesting new results. First, the financial integration measure based on portfolio equity and FDI stocks (GEQ) turns out to have a large impact on top income shares, suggesting that the channel through which globalization affects income concentration is through FDI/equity flows. Second, we find strong support for the progressivity of taxation: there is an almost one to one negative effect of higher tax on top income (top 0.1%), which declines monotonically until the top 10% class

Optimized coupling of cold atoms into a fiber using a blue-detuned hollow-beam funnel

We theoretically investigate the process of coupling cold atoms into the core of a hollow-core photonic-crystal optical fiber using a blue-detuned Laguerre-Gaussian beam. In contrast to the use of a red-detuned Gaussian beam to couple the atoms, the blue-detuned hollow-beam can confine cold atoms to the darkest regions of the beam thereby minimizing shifts in the internal states and making the guide highly robust to heating effects. This single optical beam is used as both a funnel and guide to maximize the number of atoms into the fiber. In the proposed experiment, Rb atoms are loaded into a magneto-optical trap (MOT) above a vertically-oriented optical fiber. We observe a gravito-optical trapping effect for atoms with high orbital momentum around the trap axis, which prevents atoms from coupling to the fiber: these atoms lack the kinetic energy to escape the potential and are thus trapped in the laser funnel indefinitely. We find that by reducing the dipolar force to the point at which the trapping effect just vanishes, it is possible to optimize the coupling of atoms into the fiber. Our simulations predict that by using a low-power (2.5 mW) and far-detuned (300 GHz) Laguerre-Gaussian beam with a 20-{\mu}m radius core hollow-fiber it is possible to couple 11% of the atoms from a MOT 9 mm away from the fiber. When MOT is positioned further away, coupling efficiencies over 50% can be achieved with larger core fibers.Comment: 11 pages, 12 figures, 1 tabl