Full Sky Study of Diffuse Galactic Emission at Decimeter Wavelengths

A detailed knowledge of the Galactic radio continuum is of high interest for studies of the dynamics and structure of the Galaxy as well as for the problem of foreground removal in Cosmic Microwave Background measurements. In this work we present a full-sky study of the diffuse Galactic emission at frequencies of few GHz, where synchrotron radiation is by far the dominant component. We perform a detailed combined analysis of the extended surveys at 408, 1420 and 2326 MHz (by Haslam et al. 1982, Reich 1982, Reich & Reich, 1986 and Jonas et al. 1998, respectively). Using the technique applied by Schlegel et al. (1998) to the IRAS data, we produce destriped versions of the three maps. This allows us to construct a nearly-full-sky map of the spectral index and of the normalization factor with sub-degree angular resolution. The resulting distribution of the spectral indices has an average of beta = 2.695 and dispersion sigma_{beta} = 0.120. This is representative for the Galactic diffuse synchrotron emission, with only minor effects from free-free emission and point sources.Comment: 10 pages, 16 jpeg figures, accepted to Astronomy & Astrophysics, Comments and figure adde

Right Taste, Wrong Place’: Local Food Cultures, (Dis)identification and the Formation of Middle-class Identity

This article investigates how culinary taste contributes to the formation of middle class identity in a working class context in the UK. We explore practices of food consumption among a group of individuals working at a UK university located in a working class city. We find a rather limited and discrepant cosmopolitanism, in which culinary practices are evaluated in terms of those worth engaging in, and those not worth engaging in, based on their ‘user friendliness’ for cosmopolitan middle class dispositions. Depictions of the local food culture as lacking are also dominant, used as a negative ground against which these dispositions are hierarchically formulated. Here middle class culinary tastes seem to be driven by disengagement with the wrong sort of place and a relatively closed alignment with the ‘proper’ and the ‘safe’ rather than by any open creative individuality

EFFECTS OF CHRONIC NITRIC OXIDE DEPRIVATION ON ENDOTHELIAL CELL BEHAVIOUR

The endothelium explicates its physiological functions by producing active molecules, among which nitric oxide (NO) is particularly important. It is well known that endothelial dysfunction (ED), i.e. an impaired function of the endothelium coupled with a reduced release of NO, is a risk factor for atherosclerosis together with a list of conditions such as hypertension, hypercholesterolemia, smoking, diabetes, and the aging process itself. These conditions are also associated with a significant increase in Reactive Oxygen Species (ROS) in the vascular wall that may contribute to the establishment of ED and to the development of its late effect on cardiovascular system. In the present study, the behavioural and molecular consequences deriving from chronic NO deprivation were investigated in human primary endothelial cells (human umbilical vein endothelial cells, HUVECs). To inhibit NO formation, endothelial nitric oxide synthase (eNOS) was chronically inhibited by treatment with L-NG-Nitroarginine methyl ester (L-NAME), a structural analogue of L-arginine that competitively block the active site of the enzyme, or by transfection with a siRNA specific for eNOS. We observed that a 48-h L-NAME treatment induced in HUVECs a higher migratory capability (evaluated by chemotaxis assays in Boyden\u2019s chamber) which was independent of the reduced activity of the cyclic GMP/protein kinase G pathway present in chronically NO deprived HUVECs. In the attempt to explain the mechanism(s) through which NO deficiency enhances migration, we investigated if chronic L-NAME treatment affected the expression and production of Vascular Endothelial Growth Factor (VEGF) and of its receptor KDR. RT-qPCR analyses, accompanied by ELISA assays and western blot analyses, demonstrated that both VEGF and KDR mRNAs and proteins were significantly augmented in L-NAME treated cells, thus suggesting the establishment of an autocrine loop responsible for the increased migration. Increased VEGF production and cell motility are typical events occurring in hypoxic cancer cells, due to the accumulation of hypoxia-inducible factor-1\u3b1 (HIF-1\u3b1), which plays a major role in the transcriptional activation of genes encoding angiogenic factors. Similarly, induction of VEGF expression during hypoxia has been described in endothelial cells (ECs). Interestingly, we observed a significant nuclear accumulation of HIF-1\u3b1 in HUVECs chronically treated with L-NAME. Moreover, the transcriptional activity of HIF-1\u3b1 was responsible for the increases in VEGF/KDR expression and migration since the transfection with \u394ARNT (a dominant negative form of the HIF-1\u3b2 subunit that maintains the capacity of forming an heterodimer but cannot bind DNA) is able to totally blunt both the effects in L-NAME treated HUVECs, thus confirming the involvement of an autocrine loop in the pro-migratory effect induced by NO deprivation. The dependence of HIF-1\u3b1 stabilization from NO deficiency was confirmed by using the NO donor DETA/NO. Very low doses of DETA/NO reverted both the HIF-1\u3b1 accumulation and the consequent increases in VEGF expression and cell motility induced by L-NAME treatment. Furthermore, to investigate whether the observed effects were due to the specific inhibitory effect of L-NAME on eNOS activity, we knocked-down the enzyme by using RNA interference methodology. In eNOS silenced cells, HIF-1\u3b1 accumulated in the nucleus and VEGF production was enhanced thus confirming the dependence of the observed effects on eNOS inhibition. All these results suggest that basal release of NO may act as a negative controller of HIF-1\u3b1 levels and cell motility in HUVECs with important consequences on ECs physiology. In the attempt to unravel the pathway(s) linking NO deficiency to HIF-1\u3b1 accumulation and activity, we focus our attention on ROS since their formation has been involved in HIF-1\u3b1 stabilization in normoxia. We found that acute treatment with L-NAME induced in HUVECs an early and transient burst in ROS formation that was fully prevented by the presence of the antioxidant N-acetylcysteine (NAC). HIF-1\u3b1 accumulation was reduced by 45% in the presence of NAC indicating that the peak of ROS was only partially involved in its stabilization. On the contrary, NAC did not affect the increase in cell migration in ECs chronically deprived of NO. At variance with acute treatment, chronic L-NAME exposure gave rise to an antioxidant environment characterized by a reduction in cellular ROS content accompanied by an increase in superoxide dismutase-2 (SOD-2) expression and activity. Importantly, this protective response was accompanied by the nuclear accumulation of the transcription factor NF-E2-related factor-2 (Nrf2) that was fully prevented in the presence of NAC. These results suggest the establishment of an antioxidant status in HUVECs chronically deprived of NO in the attempt to neutralize any further cell damage induced by loss of NO. In addition, since NO plays an important role in promoting mitochondrial biogenesis in different cell types and tissues, we analyzed the mitochondrial mass and function in HUVECs after NO deprivation. Long term L-NAME treatment induced a significant reduction in mitochondrial DNA (mtDNA) accompanied by decreases in the incorporation of the metabolic indicator MTS, in cellular ATP content, and in oxygen consumption. In agreement, the silencing of eNOS was able to decrease mtDNA and total cellular ATP levels thus confirming that loss of NO sustained the onset of mitochondrial dysfunction in HUVECs. Importantly, metabolic effects observed in chronically NO deprived ECs was independent of both HIF-1\u3b1 activity and ROS generation. In conclusion, we demonstrated that an endothelial deficit of NO, by mimicking the in vivo early phase of ED, induces important physiological modifications in human ECs. In particular, loss of NO leads to the accumulation and transcriptional activation of HIF-1\u3b1 responsible for the enhanced VEGF/KDR expression and cell motility, and to the establishment of mitochondrial dysfunction. Importantly, most of the peculiar features shown by long term NO deprived HUVECs are independent of acute ROS generation, and must therefore depend on other pathways triggered by NO loss. On the contrary, ROS formation appears to be totally responsible for the Nrf2 accumulation that might account for the establishment of an adaptive antioxidant status in response to oxidative stress. Further experiments will be necessary to fully characterize our in vitro model of ED and to elucidate the molecular mechanism(s) involved in HIF-1\u3b1 stabilization. Our model should however represents an useful system for the study and the identification of innovative pharmacological targets and markers for ED, thus contributing to a better knowledge of the endothelium behavior in the absence of NO and to an improved comprehension of the molecular mechanisms involved in the onset of cardiovascular pathologies

Huge excitonic effects in layered hexagonal boron nitride

The calculated quasiparticle band structure of bulk hexagonal boron nitride using the all-electron GW approximation shows that this compound is an indirect-band-gap semiconductor. The solution of the Bethe-Salpeter equation for the electron-hole two-particle Green function has been used to compute its optical spectra and the results are found in excellent agreement with available experimental data. A detailed analysis is made for the excitonic structures within the band gap and found that the excitons belong to the Frenkel class and are tightly confined within the layers. The calculated exciton binding energy is much larger than that obtained by Watanabe {\it et al} using a Wannier model to interpret their experimental results and assuming that h-BN is a direct-band-gap semiconductor.Comment: 4 pages, 3 figure

Optimization of DNA recovery and amplification from non-carbonized archaeobotanical remains

Ancient DNA (aDNA) recovered from archaeobotanical remains can provide key insights into many prominent archaeological research questions, including processes of domestication, past subsistence strategies, and human interactions with the environment. However, it is often difficult to isolate aDNA from ancient plant materials, and furthermore, such DNA extracts frequently contain inhibitory substances that preclude successful PCR amplification. In the age of high-throughput sequencing, this problem is even more significant because each additional endogenous aDNA molecule improves analytical resolution. Therefore, in this paper, we compare a variety of DNA extraction techniques on primarily desiccated archaeobotanical remains and identify which method consistently yields the greatest amount of purified DNA. In addition, we test five DNA polymerases to determine how well they replicate DNA extracted from non-charred ancient plant remains. Based upon the criteria of resistance to enzymatic inhibition, behavior in quantitative real-time PCR, replication fidelity, and compatibility with aDNA damage, we conclude these polymerases have nuanced properties, requiring researchers to make educated decisions as to which one to use for a given task. The experimental findings should prove useful to the aDNA and archaeological communities by guiding future research methodologies and ensuring precious archaeobotanical remains are studied in optimal ways, and may thereby yield important new perspectives on the interactions between humans and past plant communities

Hepatocellular carcinoma in hepatitis-negative patients with thalassemia intermedia: a closer look at the role of siderosis

Abstract Patients with thalassemia are often exposed to several risk factors for developing hepatocellular carcinoma (HCC) due to their repeated transfusions. However, even transfusion-independent patients with thalassemia intermedia (TI) can develop HCC, which is mainly attributed to a state of iron overload. We report here two cases and review the literature for the association between TI and HCC. Along with our cases, a total of 36 cases of HCC in thalassemic patients were reported in the literature. Of these, 22 (61%) were TI patients with 6 (27%) of them being hepatitis B and C negative. There was no consistency in their characteristics; therefore, we recommended screening thresholds for HCC in TI patients based on their total liver iron concentration (LIC)

Optical properties of organically functionalized silicon surfaces : Uracil-like nucleobases on Si(001)

We predict UV reflectance anisotropy spectra (RAS) of the organically functionalized silicon (001) surface covered by pyrimidinic uracil-like nucleobases. First-principles results based on density functional theory show characteristic spectral features appearing in the UV range between 3 and 7 eV, besides the expected quench in the well-known two-minima RAS signal of clean Si(001). Nucleobase adsorption in the energetically favored \u201cdimer bridge\u201d configuration gives rise to a characteristic RAS line shape, common to thymine, uracil, and 5-fluorouracil. We trace back the origin of such spectral features by singling out RAS structures induced by relaxation and passivation effects on the Si surface, and those directly associated with molecular excitations. The former turn out to be the same for the three nucleobases, and are totally unaffected by molecular tilting. The sign and position of the latter RAS peaks at higher energy exhibit a moderate nucleobase dependence, and can be fully rationalized in terms of the molecular orbitals involved. The present theoretical results call for a RAS experimental study in the UV region extending up to 436\u20137 eV

Impact ionization in GaAs: a screened exchange density functional approach

Results are presented of a fully ab-initio calculation of impact ionization rates in GaAs within the density functional theory framework, using a screened-exchange formalism and the highly precise all-electron full-potential linearized augmented plane wave (FLAPW) method. The calculated impact ionization rates show a marked orientation dependence in {\bf k} space, indicating the strong restrictions imposed by the conservation of energy and momentum. This anisotropy diminishes as the impacting electron energy increases. A Keldysh type fit performed on the energy-dependent rate shows a rather soft edge and a threshold energy greater than the direct band gap. The consistency with available Monte Carlo and empirical pseudopotential calculations shows the reliability of our approach and paves the way to ab-initio calculations of pair production rates in new and more complex materials.Comment: 11 pages, 4 figures, Submitted to Phys. Rev.