Scalar mesons in a finite volume

Using effective field theory methods, we discuss the extraction of the mass and width of the scalar mesons f0(980) and a0(980) from the finite-volume spectrum in lattice QCD. In particular, it is argued that the nature of these states can be studied by invoking twisted boundary conditions, as well as investigating the quark mass dependence of the spectrum.Comment: 18 pages, 3 figure

Ultrasonic Fatigue Analysis on Steel Specimen with Temperature Control : Evaluation of Variable Temperature Effect

Non peer reviewe

Deep radio observations of the radio halo of the bullet cluster 1E 0657-55.8

We present deep 1.1-3.1 GHz Australia Telescope Compact Array observations of the radio halo of the bullet cluster, 1E 0657-55.8. In comparison to existing images of this radio halo the detection in our images is at higher significance. The radio halo is as extended as the X-ray emission in the direction of cluster merger but is significantly less extended than the X-ray emission in the perpendicular direction. At low significance we detect a faint second peak in the radio halo close to the X-ray centroid of the smaller sub-cluster (the bullet) suggesting that, similarly to the X-ray emission, the radio halo may consist of two components. Finally, we find that the distinctive shape of the western edge of the radio halo traces out the X-ray detected bow shock. The radio halo morphology and the lack of strong point-to-point correlations between radio, X-ray and weak-lensing properties suggests that the radio halo is still being formed. The colocation of the X-ray shock with a distinctive radio brightness edge illustrates that the shock is influencing the structure of the radio halo. These observations support the theory that shocks and turbulence influence the formation and evolution of radio halo synchrotron emission.Comment: 15 pages, 16 figures, 3 tables. Accepted by MNRA

Another shock for the Bullet cluster, and the source of seed electrons for radio relics

With Australia Telescope Compact Array observations, we detect a highly elongated Mpc-scale diffuse radio source on the eastern periphery of the Bullet cluster 1E0657-55.8, which we argue has the positional, spectral and polarimetric characteristics of a radio relic. This powerful relic (2.3+/-0.1 x 10^25 W Hz^-1) consists of a bright northern bulb and a faint linear tail. The bulb emits 94% of the observed radio flux and has the highest surface brightness of any known relic. Exactly coincident with the linear tail we find a sharp X-ray surface brightness edge in the deep Chandra image of the cluster -- a signature of a shock front in the hot intracluster medium (ICM), located on the opposite side of the cluster to the famous bow shock. This new example of an X-ray shock coincident with a relic further supports the hypothesis that shocks in the outer regions of clusters can form relics via diffusive shock (re-)acceleration. Intriguingly, our new relic suggests that seed electrons for reacceleration are coming from a local remnant of a radio galaxy, which we are lucky to catch before its complete disruption. If this scenario, in which a relic forms when a shock crosses a well-defined region of the ICM polluted with aged relativistic plasma -- as opposed to the usual assumption that seeds are uniformly mixed in the ICM -- is also the case for other relics, this may explain a number of peculiar properties of peripheral relics.Comment: 10 pages, 9 figures, 1 table, accepted for publication in MNRA

Generalized L\"uscher Formula in Multi-channel Baryon-Meson Scattering

L\"uscher's formula relates the elastic scattering phase shifts to the two-particle energy levels in a finite cubic box. The original formula was obtained for elastic scattering of two massive spinless particles in the center of mass frame. In this paper, we consider the case for the scattering of a spin 1/2 particle with a spinless particle in multi-channel scattering. A generalized relation between the energy of two particle system and the scattering matrix elements is established. We first obtain this relation using quantum-mechanics in both center-of-mass frame and in a general moving frame. The result is then generalized to quantum field theory using methods outlined in Ref. \cite{Hansen:2012tf}. We verify that the results obtained using both methods are equivalent up to terms that are exponentially suppressed in the box size.Comment: One reference adde

Spatial Configuration and Vehicular Movement: a nationwide correlational study

We provide the most comprehensive study to date on the correlation between network centrality measures and vehicular movement flows, using a model of the UK’s entire road network (2,031,971 nodes) and a very large dataset of vehicular movement counts (20,752 instances, evenly distributed over the UK’s territory). We describe the statistical associations between observed vehicular flows and the values of betweenness centrality of the road-network nodes where such flows were measured, the latter calculated using Euclidean and angular distance functions, across a number of increasing radii, from the local to the supra-regional scales. Relations to road capacity are also discussed in principal road networks where this is known. The geographical comprehensiveness of our model and the size of our movement sample allows us to state, with unprecedented statistical validity, the clear outperformance of angular distance over Euclidean distance, on what concerns the effect sizes of the studied correlations. We also demonstrate the existence of two clearly different regimes of association between movement and centrality, occurring on the background and foreground networks of cities, which may be interpreted as new evidence of the dual structure of urban form, proposed by space syntax

Diabetes Insípida Como Causa de Febre

A Diabetes Insípida é uma das causas pouco habituais de febre de etiologia indeterminada. Descrevemos o caso de urna lactente internado aos nove meses de idade com febre, má progressão ponderal e atraso no desenvolvimento motor. As causas habituais destas situações foram excluídas por exames exaustivos. Alguns meses mais tarde constatámos o aparecimento de poliúria e polidipsia. A prova com desmopressina fez o diagnóstico de Diabetes Insípida Central que foi confirmada com a resposta à terapêutica

Sensores baseados em nanotubos de carbono funcionalizados por ligação não-covalente

A pesquisa na área dos nanomateriais de carbono, como os nanotubos de carbono (CNTs), tem crescido muito rapidamente devido às suas propriedades térmicas, eletrónicas e mecânicas. Muitos esforços têm sido realizados para aumentar a solubilidade destes materiais em diversos solventes e obter dispersões estáveis. Uma das estratégias para dispersar os CNTs consiste na funcionalização química, que apresenta como desvantagem a destruição da estrutura sp2 do carbono destes materiais. Neste últimos anos surgiram vários estudos baseados na funcionalização não-covalente com o intuito de manter as suas propriedades estruturais. Com este fim, tem sido utilizadas estruturas poliaromáticas substituídas como perilenos e pirenos que podem estabelecer interações do tipo π-π com a superfície aromática dos CNTs ou do grafeno. Neste trabalho pretende-se apresentar uma revisão bibliográfica da utilização da funcionalização nãocovalente no desenvolvimento de sensores e biossensores eletroquímicos em substrato de materiais nanoestruturados de carbono (MWCNTs, SWCNTs, grafeno)

Factors associated with increased survival after surgical resection of glioblastoma in octogenarians.

Elderly patients with glioblastoma represent a clinical challenge for neurosurgeons and oncologists. The data available on outcomes of patients greater than 80 undergoing resection is limited. In this study, factors linked to increased survival in patients over the age of 80 were analyzed. A retrospective chart review of all patients over the age of 80 with a new diagnosis of glioblastoma and who underwent surgical resection with intent for maximal resection were examined. Patients who had only stereotactic biopsies were excluded. Immunohistochemical expression of oncogenic drivers (p53, EGFR, IDH-1) and a marker of cell proliferation (Ki-67 index) performed upon routine neuropathological examination were recorded. Stepwise logistic regression and Kaplan Meier survival curves were plotted to determine correlations to overall survival. Fifty-eight patients fit inclusion criteria with a mean age of 83 (range 80-93 years). The overall median survival was 4.2 months. There was a statistically significant correlation between Karnofsky Performance Status (KPS) and overall survival (P < 0.05). There was a significantly longer survival among patients undergoing either radiation alone or radiation and chemotherapy compared to those who underwent no postoperative adjuvant therapy (p < 0.05). There was also an association between overall survival and lack of p53 expression (p < 0.001) and lack of EGFR expression (p <0.05). In this very elderly population, overall survival advantage was conferred to those with higher preoperative KPS, postoperative adjuvant therapy, and lack of protein expression of EGFR and p53. These findings may be useful in clinical decision analysis for management of patients with glioblastoma who are octogenarians, and also validate the critical role of EGFR and p53 expression in oncogenesis, particularly with advancing age