Numerical study of the scaling properties of SU(2) lattice gauge theory in Palumbo non-compact regularization

In the framework of a non-compact lattice regularization of nonabelian gauge theories we look, in the SU(2) case, for the scaling window through the analysis of the ratio of two masses of hadronic states. In the two-dimensional parameter space of the theory we find the region where the ratio is constant, and equal to the one in the Wilson regularization. In the scaling region we calculate the lattice spacing, finding it at least 20% larger than in the Wilson case; therefore the simulated physical volume is larger.Comment: 24 pages, 7 figure

Osteocytes Specific GSK3 Inhibition Affects In Vitro Osteogenic Differentiation.

Osteocytes, the most important regulators of bone processes, are producers of molecules (usually proteins) that act as signals in order to communicate with nearby cells. These factors control cell division (proliferation), differentiation, and survival. Substantial evidence showed different signaling pathways activated by osteocytes and involved in osteoblast differentiation, in particular in the last decade, when the Wingless-related integration site (WNT) pathway assumed a critical large importance. WNT activation by inhibiting glycogen synthase kinase 3 (GSK-3) causes bone anabolism, making GSK3 a potential therapeutic target for bone diseases. In our study, we hypothesized an important role of the osteocyte MLO-Y4 conditioned medium in controlling the differentiation process of osteoblast cell line 2T3. We found an effect of diminished differentiation capability of 2T3 upon conditioning with medium from murine long bone osteocyte-Y4 cells (MLO-Y4) pre-treated with GSK3 inhibitor CHIR2201. The novel observations of this study provide knowledge about the inhibition of GSK3 in MLO-Y4 cells. This strategy could be used as a plausible target in osteocytes in order to regulate bone resorption mediated by a loss of osteoblasts activity through a paracrine loop

Loop Variables for compact two-dimensional quantum electrodynamics

Variables parametrized by closed and open curves are defined to reformulate compact U(1) Quantum Electrodynamics in the circle with a massless fermion field. It is found that the gauge invariant nature of these variables accommodates into a regularization scheme for the Hamiltonian and current operators that is specially well suited for the study of the compact case. The zero mode energy spectrum, the value of the axial anomaly and the anomalous commutators this model presents are hence determined in a manifestly gauge invariant manner. Contrary to the non compact case, the zero mode spectrum is not equally spaced and consequently the theory does not lead to the spectrum of a free scalar boson. All the states are invariant under large gauge transformations. In particular, that is the case for the vacuum, and consequently the $\theta$-dependence does not appear.Comment: 24 pages, 1 figure, to be published in Phys. Rev.

Limitations on the role of the hyporheic zone in chromium natural attenuation in a contaminated urban stream

The urban hyporheic zone may offer natural attenuation potential for contaminants. This potential is contaminant-specific and may be spatially and temporally variable. The aim of this study was the assessment of the natural attenuation potential of the hyporheic zone of an urban stream receiving hexavalent chromium (Cr)-rich effluents from the historical land disposal of chromite ore processing residue (COPR) in Glasgow, Scotland. The evidence based approach involved the use of a network of multilevel piezometers for best capturing potential anoxic field conditions and fine-scale spatial gradients in solute concentrations of surface water and porewater. In-situ porewater sampling was integrated with sediment sampling and reach-scale monitoring of stream water quality. The results show a sharp decrease of total dissolved (filtered <0.45 μm) Cr concentrations at the surface water – sediment boundary in all profiles, from Cr mean values of 1100 μg l−1 in surface water to 5 μg l−1 in porewater. Chromium speciation analysis indicates that no Cr(VI) was detectable in the neutral pH, moderately reducing porewater, while it was the dominant species in surface water. Evidence of historical COPR detrital grains contributed to the total Cr concentrations (size fraction <150 μm) up to 8800 mg kg−1 in the streambed sediment. The abundance in the porewater of Fe (mean value = 1700 μg l−1), mainly as Fe(II), a natural electron donor for Cr(VI) reduction to Cr(III), indicates a high natural attenuation potential of the hyporheic zone for downwelling dissolved Cr, through Cr(VI) reduction to Cr(III) and the formation of Cr(III) solids of low solubility. Authigenic Cr-rich rims on particles also documented active Cr precipitation from solution in the fine sediments. Large short-term changes of stream stage and stream water composition were not reflected in the hyporheic conservative (chloride) and reactive solute composition. This result indicates only limited surface water infiltration and suggests that small advective exchange might limit the effectiveness of the hyporheic zone for enhancing Cr surface water quality at the reach-scale. This is supported by further evidence from preliminary surface water quality synoptic sampling which shows only moderate to low downstream decrease in surface water Cr concentrations. The surface water investigation needs to be supported by combined water quality-flow monitoring and to be extended to a wider range of temporal and spatial scales to corroborate the reach-scale findings

Radio Lobes of Pictor A: an X-ray spatially resolved Study

A new XMM observation has made possible a detailed study of both lobes of the radio galaxy Pictor A. Their X-ray emission is of non thermal origin and due to Inverse Compton scattering of the microwave background photons by relativistic electrons in the lobes, as previously found. In both lobes, the equipartition magnetic field (Beq) is bigger than the Inverse Compton value (Bic), calculated from the radio and X-ray flux ratio. The Beq/Bic ratio never gets below 2, in spite of the large number of reasonable assumptions tested to calculate Beq, suggesting a lobe energetic dominated by particles. The X-ray data quality is good enough to allow a spatially resolved analysis. Our study shows that Bic varies through the lobes. It appears to increase behind the hot spots. On the contrary, a rather uniform distribution of the particles is observed. As a consequence, the radio flux density variation along the lobes appears to be mainly driven by magnetic field changes.Comment: 15 pages, 3 figures, ApJ accepte

Spitzer Observations of CO2 Ice Towards Field Stars in the Taurus Molecular Cloud

We present the first Spitzer Infrared Spectrograph observations of the 15.2 micron bending mode of CO2 ice towards field stars behind a quiescent dark cloud. CO2 ice is detected towards 2 field stars (Elias 16, Elias 3) and a single protostar (HL Tau) with anabundance of ~15-20% relative to water ice. CO2 ice is not detected towards the source with lowest extinction in our sample, Tamura 17 (A_V = 3.9m). A comparison of the Elias 16 spectrum with laboratory data demonstrates that the majority of CO2 ice is embedded in a polar H2O-rich ice component, with ~15% of CO2 residing in an apolar H2O-poor mantle. This is the first detection of apolar CO2 towards a field star. We find that the CO2 extinction threshold is A_V = 4m +/- 1m, comparable to the threshold for water ice, but significantly less than the threshold for CO ice, the likely precursor of CO2. Our results confirm CO2 ice forms in tandem with H2O ice along quiescent lines of sight. This argues for CO2 ice formation via a mechanism similar to that responsible for H2O ice formation, viz. simple catalytic reactions on grain surfaces.Comment: Accepted by Astrophysical Journal Letter

Understanding the Roles of the Hedgehog Signaling Pathway during T-Cell Lymphopoiesis and in T-Cell Acute Lymphoblastic Leukemia (T-ALL)

: The Hedgehog (HH) signaling network is one of the main regulators of invertebrate and vertebrate embryonic development. Along with other networks, such as NOTCH and WNT, HH signaling specifies both the early patterning and the polarity events as well as the subsequent organ formation via the temporal and spatial regulation of cell proliferation and differentiation. However, aberrant activation of HH signaling has been identified in a broad range of malignant disorders, where it positively influences proliferation, survival, and therapeutic resistance of neoplastic cells. Inhibitors targeting the HH pathway have been tested in preclinical cancer models. The HH pathway is also overactive in other blood malignancies, including T-cell acute lymphoblastic leukemia (T-ALL). This review is intended to summarize our knowledge of the biological roles and pathophysiology of the HH pathway during normal T-cell lymphopoiesis and in T-ALL. In addition, we will discuss potential therapeutic strategies that might expand the clinical usefulness of drugs targeting the HH pathway in T-ALL

Topological properties of a non-Hermitian quasi-one-dimensional chain with a flat band

We investigate the spectral properties of a non-Hermitian quasi-one-dimensional lattice in two possible dimerization configurations. Specifically, we focus on a non-Hermitian diamond chain that presents a zero-energy flat band. The flat band originates from wave interference and results in eigenstates with a finite contribution only on two sites of the unit cell. To achieve the non-Hermitian characteristics, we introduce non-reciprocal intrasite hopping terms in the chain. This leads to the accumulation of eigenstates on the boundary of the system, known as the non-Hermitian skin effect. Despite this accumulation of eigenstates, for one of the two possible configurations, we can characterize the presence of non-trivial edge states at zero energy by a real-space topological invariant known as the biorthogonal polarization. We show that this invariant, evaluated using the destructive interference method, characterizes the non-trivial phase of the non-Hermitian diamond chain. For the other possible non-Hermitian configuration, we find that there is a finite quantum metric associated with the flat band. Additionally, we observe the skin effect despite having the system a purely real or imaginary spectrum. For both configurations, we show that two non- Hermitian diamond chains can be mapped into two models of the Su-Schrieffer-Heeger chains, either non-Hermitian and Hermitian, in the presence of a flat band. This mapping allows us to draw valuable insights into the behavior and properties of these systems.Comment: 14 pages, 9 figure

Measurements of proton induced reaction cross sections on 120Te for the astrophysical p-process

The total cross sections for the 120Te(p,gamma)121I and 120Te(p,n)120I reactions have been measured by the activation method in the effective center-of-mass energies between 2.47 MeV and 7.93 MeV. The targets were prepared by evaporation of 99.4 % isotopically enriched 120Te on Aluminum and Carbon backing foils, and bombarded with proton beams provided by the FN tandem accelerator at the University of Notre Dame. The cross sections and $S$ factors were deduced from the observed gamma ray activity, which was detected off-line by two Clover HPGe detectors mounted in close geometry. The results are presented and compared with the predictions of statistical model calculations using the codes NON-SMOKER and TALYS.Comment: 17 pages, 5 figures, 5 tables, regular articl