Resolving the bow-shock nebula around the old pulsar PSR B1929+10 with multi-epoch Chandra observations

We have studied the nearby old pulsar PSR B1929+10 and its surrounding interstellar medium utilizing the sub-arcsecond angular resolution of the Chandra X-ray Observatory. The Chandra data are found to be fully consistent with the results obtained from deep XMM-Newton observations as far as the pulsar is concerned. We confirm the non-thermal emission nature of the pulsar's X-radiation. In addition to the X-ray trail already seen in previous observations by the ROSAT and XMM-Newton X-ray observatories, we discovered an arc-like nebula surrounding the pulsar. We interpret the feature as a bow-shock nebula and discuss its energetics in the context of standard shock theory.Comment: Accepted by A&A, revised in accordance with referee's comment

European Food Quality Policy: The Importance of Geographical Indications, Organic Certification and Food Quality Assurance Schemes in European Countries

In the early 1990s reform of the EU’s Common Agricultural Policy led to a change in emphasis away from price into policies to promote rural development, in part through improvements to food quality. Geographic indicators are only one of a range of EU policies designed to foster these goals. Geographic indicators are put within the context of the wider quality enhancement policies that include quality assurance schemes and organic production. There appears to be considerable regional differences within the EU when it comes to the use of the various quality-enhancing policies available. The member states of the EU can be grouped into four different clusters, each characterized by a different quality policy strategy.European Union, food quality, geographic indicators, regional differences, Food Consumption/Nutrition/Food Safety, International Relations/Trade,

Second harmonic generation confocal microscopy of collagen type I from rat tendon cryosections

We performed second harmonic generation (SHG) imaging of collagen in rat-tendon cryosections, using femtosecond laser scanning confocal microscopy, both in backscattering and transmission geometries. SHG transmission images of collagen fibers were spatially resolved due to a coherent, directional SHG component. This effect was enhanced with the use of an index-matching fluid (n(l) 1.52). The average SHG intensity oscillated with wavelength in the backscattered geometry (isotropic SHG component), whereas the spectral profile was consistent with quasi-phase-matching conditions in transmission geometry (forward propagating, coherent SHG component) around 440 nm (lambda(p) 880 nm). Collagen type I from bovine Achilles tendon was imaged for SHG in the backscattered geometry and its first-order effective nonlinear coefficient was determined (vertical bar d(eff)vertical bar approximate to 0.085(+/- 0.025) x 10-(12)mV(-1)) by comparison to samples of inorganic materials with known effective nonlinear coefficients (LiNbO3 and LiIO3). The SHG spectral response of collagen type I from bovine Achilles tendon matched that of the rat-tendon cryosections in backscattered geometry. Collagen types I, II, and VI powders (nonfibrous) did not show any detectable SHG, indicating a lack of noncentrosymmetric crystalline structure at the molecular level. The various stages of collagen thermal denaturation were investigated in rat-tendon cryosections using SHG and bright-field imaging. Thermal denaturation resulted in the gradual destruction of the SHG signal

Dynamical Measurements of the Interior Structure of Exoplanets

Giant gaseous planets often reside on orbits in sufficient proximity to their host stars for the planetary quadrupole gravitational field to become non-negligible. In presence of an additional planetary companion, a precise characterization of the system's orbital state can yield meaningful constraints on the transiting planet's interior structure. However, such methods can require a very specific type of system. This paper explores the dynamic range of applicability of these methods and shows that interior structure calculations are possible for a wide array of orbital architectures. The HAT-P-13 system is used as a case study, and the implications of perturbations arising from a third distant companion on the feasibility of an interior calculation are discussed. We find that the method discussed here is likely to be useful in studying other planetary systems, allowing the possibility of an expanded survey of the interiors of exoplanets.Comment: Accepted to Ap

Minimum weight design aspects of stiffened cylinders under compression

Survey on minimum weight design aspects of stiffened cylinders under compressio

Cu-O network dependent core-hole screening in low-dimensional cuprates: A theoretical analysis

We analyze the influence of the dimensionality on the Cu 2p_3/2 core level X-ray photoemission spectra of undoped cuprates. Both exchange splitting and delocalization properties are described within one framework using a multi-band Hubbard model. The spectral intensity is calculated by means of the Mori-Zwanzig projection technique for a CuO_4 plaquette ('zero'-dimensional), an infinite CuO_3 chain (one-dimensional), and an infinite CuO_2 plane (two-dimensional). The results are compared to the spectra of Bi_2CuO_4, Sr_2CuO_3, and Sr_2CuO_2Cl_2. Our analysis allows to distinguish between effects of the Cu-O geometry and effects from material-specific properties.Comment: REVTeX, 8 pages, 6 figures, to appear in Phys. Rev.

European food quality policy: the importance of geographical indications, organic certification and food quality insurance schemes in European countries

The protection of geographical indications, organic certification and food quality assurance schemes are the cornerstones of European food quality policy. In this paper the importance of these voluntary quality policy schemes in the different Member States of the European Union is investigated. Member States may be grouped into four cluster according to the food quality orientation.food quality policy, protected geographical indications, organic certification, quality assurance schemes, Europe, cluster, PDO, PGI, TSG, Agricultural and Food Policy, Food Consumption/Nutrition/Food Safety,

New freshwater sponges from Amazonian waters

Four species of freshwater sponges have their first register of occurrence for Amazonian waters upon specimens collected from Culuene and Sete de Setembro Rivers (Xingú basin), Tapirapés River (Araguaia basin) and Cuieiras River. Trochospongilla pennsylvanica (POTTS 1882) and Trochospongilla variabilis BONETTO & EZCURRA DE DRAGO (1973) occurred as minute specimens inside large sponges of the genus Metania GRAY (1867) or of the genus Drulia GRAY (1867). T. pennsylvanica has its first register of occurrence for the Neotropical region. Spongilla spoliata n. sp. resembles Spongilla inarmata ANNADALE (1918) and Spongilla aspinosa POTTS (1880) but is readily separated from these two species on account of the characteristic spines on its microscleres. Radiospongilla amazonensis n. sp. differs from its congeners by the particular characteristics of its megascleres and gemmoscleres