Gamow-Teller sum rule in relativistic nuclear models

Relativistic corrections are investigated to the Gamow-Teller(GT) sum rule with respect to the difference between the $\beta_-$ and $\beta_+$ transition strengths in nuclei. Since the sum rule requires the complete set of the nuclear states, the relativistic corrections come from the anti-nucleon degrees of freedom. In the relativistic mean field approximation, the total GT strengths carried by the nucleon sector is quenched by about 12% in nuclear matter, while by about 8% in finite nuclei, compared to the sum rule value. The coupling between the particle-hole states with the nucleon-antinucleon states is also discussed with the relativistic random phase approximation, where the divergence of the response function is renormalized with use of the counter terms in the Lagrangian. It is shown that the approximation to neglect the divergence, like the no-sea approximation extensively used so far, is unphysical, from the sum-rule point of view.Comment: 12 pages, Brief review for Mod. Phys. Lett. A, using ws-mpla.cl

The symptom of low mood in the prodromal stage of mild cognitive impairment and dementia: a cohort study of a community dwelling elderly population

OBJECTIVE: To investigate the symptom of low mood as a predictor of mild cognitive impairment (MCI) and its progression to dementia, taking into account: (i) MCI severity, (ii) time of assessment and (iii) interaction with other factors. METHODS: 764 cognitively healthy elderly subjects living in the community, from the Kungsholmen Project. Participants were assessed by direct interview to detect low mood. Subjects were then followed for 6 years to identify those who developed MCI. People with incident MCI were followed for a further 3 years to assess progression to dementia. RESULTS: People with low mood at baseline had a 2.7-fold (95% CI 1.9 to 3.7) increased risk of developing MCI at follow-up. The association was stronger for amnestic MCI (aMCI: HR 5.8; 95% CI 3.1 to 10.9) compared with global cognitive impairment (other cognitive impairment no dementia, oCIND: HR 2.2; 95% CI 1.5 to 3.3). ApoE-ε4 interacted with low mood in a synergistic fashion, increasing the risk of aMCI, while no interaction with psychiatric, vascular, frailty related or psychosocial factors was observed. Low mood at baseline, as opposed to low mood co-occurring with MCI, was associated with a 5.3-fold (95% CI 1.2 to 23.3) increased risk of progression to dementia in aMCI. In contrast, no association was found in oCIND. CONCLUSION: Low mood was more strongly associated with aMCI than with global cognitive impairment. Progression towards dementia was predicted only by low mood manifest in the prodromal stage of MCI. These findings indicate that low mood is particularly prominent in the very early stages of cognitive decline

Field validation of radar systems for monitoring bird migration

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this record.Advances in information technology are increasing the use of radar as a tool to investigate and monitor bird migration movements. We set up a field campaign to compare and validate outputs from different radar systems. Here we compare the pattern of nocturnal bird migration movements recorded by four different radar systems at a site in southern Sweden. Within the range of the weather radar (WR) Ängelholm, we operated a "BirdScan" (BS) dedicated bird radar, a standard marine radar (MR), and a tracking radar (TR). The measures of nightly migration intensities, provided by three of the radars (WR, BS, MR), corresponded well with respect to the relative seasonal course of migration, while absolute migration intensity agreed reasonably only between WR and BS. Flight directions derived from WR, BS and TR corresponded very well, despite very different sample sizes. Estimated mean ground speeds differed among all four systems. The correspondence among systems was highest under clear sky conditions and at high altitudes. Synthesis and applications. While different radar systems can provide useful information on nocturnal bird migration, they have distinct strengths and weaknesses, and all require supporting data to allow for species level inference. Weather radars continuously detect avian biomass flows across a wide altitude band, making them a useful tool for monitoring and predictive applications at regional to continental scales that do not rely on resolving individuals. BirdScan and marine radar's strengths are in local and low altitude applications, such as collision risks with man-made structures and airport safety, although marine radars should not be trusted for absolute intensities of movement. In quantifying flight behaviour of individuals, TR is the most informative.We acknowledge the support provided by COST – European Cooperation in Science and Technology through the Action ES1305 ‘European Network for the Radar Surveillance of Animal Movement’ (ENRAM) in facilitating this collaboration. The study received financial support from Gyllenstierna Krapperup ́s Foundation and the Centre for Animal Movement Research (CAnMove) financed by a Linnaeus grant (349-2007-8690) from the Swedish Research Council and Lund University

Continuum quasiparticle random phase approximation and the time dependent Hartree-Fock-Bogoliubov approach

Quadrupole excitations of neutron-rich nuclei are analyzed by using the linear response method in the Quasiparticle Random Phase Approximation (QRPA). The QRPA response is derived starting from the time-dependent Hartree-Fock-Bogoliubov (HFB) equations. The residual interaction between the quasiparticles is determined consistently from the two-body force used in the HFB equations, and the continuum coupling is treated exactly. Calculations are done for the neutron-rich oxygen isotopes. It is found that pairing correlations affect the low-lying states, and that a full treatment of the continuum can change the structure of the states in the giant resonance region.Comment: 17 pages, 7 figures. Revised version with comments and references adde

Meson-induced correlations of nucleons in nuclear Compton scattering

The non-resonant (seagull) contribution to the nuclear Compton amplitude at low energies is strongly influenced by nucleon correlations arising from meson exchange. We study this problem in a modified Fermi gas model, where nuclear correlation functions are obtained with the help of perturbation theory. The dependence of the mesonic seagull amplitude on the nuclear radius is investigated and the influence of a realistic nuclear density on this amplitude is dicussed. We found that different form factors appear for the static part (proportional to the enhancement constant $\kappa$) of the mesonic seagull amplitude and for the parts, which contain the contribution from electromagnetic polarizabilities.Comment: 15 pages, Latex, epsf.sty, 9 eps figures

Scaling Of Chiral Lagrangians And Landau Fermi Liquid Theory For Dense Hadronic Matter

We discuss the Fermi-liquid properties of hadronic matter derived from a chiral Lagrangian field theory in which Brown-Rho (BR) scaling is incorporated. We identify the BR scaling as a contribution to Landau's Fermi liquid fixed-point quasiparticle parameter from "heavy" isoscalar meson degrees of freedom that are integrated out from a low-energy effective Lagrangian. We show that for the vector (convection) current, the result obtained in the chiral Lagrangian approach agrees precisely with that obtained in the semi-phenomenological Landau-Migdal approach. This precise agreement allows one to determine the Landau parameter that enters in the effective nucleon mass in terms of the constant that characterizes BR scaling. When applied to the weak axial current, however, these two approaches differ in a subtle way. While the difference is small numerically, the chiral Lagrangian approach implements current algebra and low-energy theorems associated with the axial response that the Landau method misses and hence is expected to be more predictive.Comment: 39 pages, latex with 4 eps figure, modified addresses and reference

Renormalization group and Fermi liquid theory for many-nucleon systems

We discuss renormalization group approaches to strongly interacting Fermi systems, in the context of Landau's theory of Fermi liquids and functional methods, and their application to neutron matter.Comment: 40 pages, 23 figures, updated lectures given at ECT*, to appear in Springer Lecture Notes in Physic

Training adults and children with an autism spectrum disorder to be compliant with a clinical dental assessment using a TEACCH-based approach

The specific neuropsychological and sensory profile found in persons with autism spectrum disorders complicate dental procedures and as a result of this, most are treated under general anesthesia or unnecessary sedation. The main goal of the present study was to evaluate the effectiveness of a short treatment and education of autistic and related communication-handicapped children-based intervention program (five sessions) to facilitate a 10-component oral assessment in children (n = 38, aged 4¿9 years) and adults (n = 34, aged 19¿41) with autism spectrum disorder (with or without associated intellectual disability). The assessment ranges from entering into the examination room to the evaluation of the dental occlusion. There were statistically significant differences in the number of components reached and in compliance before and after the training program

Rabies screen reveals GPe control of cocaine-triggered plasticity.

Identification of neural circuit changes that contribute to behavioural plasticity has routinely been conducted on candidate circuits that were preselected on the basis of previous results. Here we present an unbiased method for identifying experience-triggered circuit-level changes in neuronal ensembles in mice. Using rabies virus monosynaptic tracing, we mapped cocaine-induced global changes in inputs onto neurons in the ventral tegmental area. Cocaine increased rabies-labelled inputs from the globus pallidus externus (GPe), a basal ganglia nucleus not previously known to participate in behavioural plasticity triggered by drugs of abuse. We demonstrated that cocaine increased GPe neuron activity, which accounted for the increase in GPe labelling. Inhibition of GPe activity revealed that it contributes to two forms of cocaine-triggered behavioural plasticity, at least in part by disinhibiting dopamine neurons in the ventral tegmental area. These results suggest that rabies-based unbiased screening of changes in input populations can identify previously unappreciated circuit elements that critically support behavioural adaptations

The influence of wind direction on the capture of the wood warbler (Phylloscopus sibilatrix), an uncommon migratory species in the western Mediterranean

The wood warbler (Phylloscopus sibilatrix) is a migratory species in the western Mediterranean wintering in the Gulf of Guinea region, West Africa. In autumn and spring, this species, along with the populations breeding in Ireland and Britain, uses the Italian peninsula as its main axis of migration. From the data of captured birds at several ringing stations in the western Mediterranean (Balearic Islands and coastal Iberian Peninsula), we analyzed capture rates of the species during spring migration from 1993 to 2007. Based on the selection of days with a significant number of captures and those without captures, we analyzed the effect of wind direction over the western Mediterranean to determine a relationship between winds and the number of captures. From a total of 663 wood warblers captured between 1993 and 2007, a total of 31 days have been selected as significant days with a high number of captures, and 31 days have been selected as no-capture days. On days of maximum captures, winds coming from an easterly direction, i.e. Algeria and Tunisia, were dominant, indicating days with a clear eastern component. Contrary to expected results, captures were also made on days when the wind direction was predominantly from a northerly direction. Analysis of the origin of the winds in north eastern Spain (western Mediterranean) revealed that the majority of northerly winds originated from Africa and not from Europe as is usual for this region. Days or periods selected as no-capture days were characterized by winds coming from a northerly (European origin) or westerly direction