582 research outputs found
Vacuum energy in the presence of a magnetic string with delta function profile
We present a calculation of the ground state energy of massive spinor fields
and massive scalar fields in the background of an inhomogeneous magnetic string
with potential given by a delta function. The zeta functional regularization is
used and the lowest heat kernel coefficients are calculated. The rest of the
analytical calculation adopts the Jost function formalism. In the numerical
part of the work the renormalized vacuum energy as a function of the radius
of the string is calculated and plotted for various values of the strength of
the potential. The sign of the energy is found to change with the radius. For
both scalar and spinor fields the renormalized energy shows no logarithmic
behaviour in the limit , as was expected from the vanishing of the heat
kernel coefficient , which is not zero for other types of profiles.Comment: 30 pages, 10 figure
Faulting of a turbidite sandstone-siltstone successions: the case study of the Macigno Formation, Tuscany, Italy
Faults in siliciclastic rocks are characterized by a great variability of fault zone architecture and relative permeability properties. This is because siliciclastic rocks (i.e turbidites) are often represented by alternating beds of various thickness and grain size forming a succession of strata with contrasting mechanical properties. For example, the presence of sandstone and clay-rich layers is responsible for the simultaneous occurrence of brittle and ductile deformation, known as “clay smear structures”. Moreover, numerous studies have identified grain size as one of the main influencing factors for fault nucleation processes and fracture intensity in the damage zone. In this work, we present the results of field and laboratory analyses performed on the Macigno Formation cropping out along the coast of western Tuscany. Here, the Macigno Formation is represented by Late Oligocene foredeep siliciclastic succession dominated by turbiditic sandstones with minor siltstones, mudstones, marls and shales. Thin section and 3D analyses, performed by X-ray Synchrotron tomography, allowed us to characterize the grain size and grain and cement composition of studied rocks. Grain size varies from channelized fine-grained sandstones to granule-conglomerates beds (0.006 mm to 4 mm) alternating with heterolithic levee strata of siltstones to fine-grained sandstones (0.0035-0.008 mm). The lithic components consist of metamorphic rocks by 70-80%, magmatic rocks by 15-20% and sedimentary rocks by 5-15%. The turbidite beds are normally well-cemented (by quartz and calcite) and heavily faulted and fractured.
Investigated faults show dip-, oblique- and and strike-slip motion and their displacement range from 10s of
centimetres to 10s of metres. We documented how both the grain size and the mechanical properties of the
alternating beds strongly control the fault zone architecture, in particular in terms of damage zone thickness and fracture frequency. The fault rock types (i.e. breccia vs. gauge) are strictly related to the amount of displacement as well as to the grain size and the cementation of the sandstone. Furthermore, the development of clay smear structures are enhanced by the presence of interbedded thin clay-rich layers
Full Multiple Scattering Analysis of XANES at the Cd L 3- and O K- Edges in CdO Films Combined with a Soft-X-Ray Emission Investigation
X-ray absorption near edge structure (XANES) at the cadmium L3 and oxygen K edges for CdO thin films grown by pulsed laser deposition method, is interpreted within the real-space multiple scattering formalism, FEFF code. The features in the experimental spectra are well reproduced by calculations for a cluster of about six and ten coordination shells around the absorber for L3 edge of Cd and K edge of O, respectively. The calculated projected electronic density of states is found to be in good agreement with unoccupied electronic states in experimental data and allows to conclude that the orbital character of the lowest energy of the conductive band is Cd 5s-O 2p[sigma]*. The charge transfer has been quantified and not purely ionic bonding has been found. Combined XANES and resonant inelastic x-ray scattering measurements allow us to determine the direct and indirect band gap of investigated CdO films to be ~2.4 eV and ~0.9 eV, respectively
X-ray absorption spectroscopy study of diluted magnetic semiconductors: Zn1-xMxSe (M = Mn, Fe, Co) and Zn1-xMnxY (Y = Se, Te)
We have investigated 3d electronic states of doped transition metals in II-VI
diluted magnetic semiconductors, Zn1-xMxSe (M = Mn, Fe, Co) and Zn1-xMnxY (Y =
Se, Te), using the transition-metal L2,3-edge X-ray absorption spectroscopy
(XAS) measurements. In order to explain the XAS spectra, we employed a
tetragonal cluster model calculation, which includes not only the full ionic
multiplet structure but also configuration interaction (CI). The results show
that CI is essential to describe the experimental spectra adequately,
indicating the strong hybridization between the transition metal 3d and the
ligand p orbitals. In the study of Zn1-xMnxY (Y = Se, Te), we also found
considerable spectral change in the Mn L2,3-edge XAS spectra for different
ligands, confirming the importance of the hybridization effects in these
materials.Comment: This paper consists of 22 pages including 4 figures. This paper is
submitted to Physical Review
Neutrophils in cancer: neutral no more
Neutrophils are indispensable antagonists of microbial infection and facilitators of wound healing. In the cancer setting, a newfound appreciation for neutrophils has come into view. The traditionally held belief that neutrophils are inert bystanders is being challenged by the recent literature. Emerging evidence indicates that tumours manipulate neutrophils, sometimes early in their differentiation process, to create diverse phenotypic and functional polarization states able to alter tumour behaviour. In this Review, we discuss the involvement of neutrophils in cancer initiation and progression, and their potential as clinical biomarkers and therapeutic targets
Non-classical forms of pemphigus: pemphigus herpetiformis, IgA pemphigus, paraneoplastic pemphigus and IgG/IgA pemphigus
The pemphigus group comprises the autoimmune intraepidermal blistering diseases classically divided into two major types: pemphigus vulgaris and pemphigus foliaceous. Pemphigus herpetiformis, IgA pemphigus, paraneoplastic pemphigus and IgG/IgA pemphigus are rarer forms that present some clinical, histological and immunopathological characteristics that are different from the classical types. These are reviewed in this article. Future research may help definitively to locate the position of these forms in the pemphigus group, especially with regard to pemphigus herpetiformis and the IgG/ IgA pemphigus.Universidade Federal de São Paulo (UNIFESP), Escola Paulista de Medicina (EPM) Dermatology DepartmentUniversidade Federal de São Paulo (UNIFESP), Escola Paulista de Medicina (EPM) Dermatology and Pathology DepartmentsUNIFESP, EPM, Dermatology DepartmentUNIFESP, EPM, Dermatology and Pathology DepartmentsSciEL
Systematic classification of the His-Me finger superfamily
The His-Me finger endonucleases, also known as
HNH or -metal endonucleases, form a large and
diverse protein superfamily. The His-Me finger domain
can be found in proteins that play an essential
role in cells, including genome maintenance, intron
homing, host defense and target offense. Its overall
structural compactness and non-specificity make
it a perfectly-tailored pathogenic module that participates
on both sides of inter- and intra-organismal
competition. An extremely low sequence similarity
across the superfamily makes it difficult to identify
and classify new His-Me fingers. Using state-of-theart
distant homology detection methods, we provide
an updated and systematic classification of His-Me
finger proteins. In this work, we identified over 100
000 proteins and clustered them into 38 groups, of
which three groups are new and cannot be found in
any existing public domain database of protein families.
Based on an analysis of sequences, structures,
domain architectures, and genomic contexts, we provide
a careful functional annotation of the poorly
characterized members of this superfamily. Our results
may inspire further experimental investigations
that should address the predicted activity and clarify
the potential substrates, to provide more detailed insights
into the fundamental biological roles of these
proteins
Association between Polymorphisms in Glutathione Peroxidase and Selenoprotein P Genes, Glutathione Peroxidase Activity, HRT Use and Breast Cancer Risk.
Breast cancer (BC) is one of the most common cancers in women. Evidence suggests that genetic variation in antioxidant enzymes could influence BC risk, but to date the relationship between selenoproteins and BC risk remains unclear. In this report, a study population including 975 Danish cases and 975 controls matched for age and hormone replacement therapy (HRT) use was genotyped for five functional single nucleotide polymorphisms (SNPs) in SEPP1, GPX1, GPX4 and the antioxidant enzyme SOD2 genes. The influence of genetic polymorphisms on breast cancer risk was assessed using conditional logistic regression. Additionally pre-diagnosis erythrocyte GPx (eGPx) activity was measured in a sub-group of the population. A 60% reduction in risk of developing overall BC and ductal BC was observed in women who were homozygous Thr carriers for SEPP1 rs3877899. Additionally, Leu carriers for GPX1 Pro198Leu polymorphism (rs1050450) were at ∼2 fold increased risk of developing a non-ductal BC. Pre-diagnosis eGPx activity was found to depend on genotype for rs713041 (GPX4), rs3877899 (SEPP1), and rs1050450 (GPX1) and on HRT use. Moreover, depending on genotype and HRT use, eGPx activity was significantly lower in women who developed BC later in life compared with controls. Furthermore, GPx1 protein levels increased in human breast adenocarcinoma MCF7 cells exposed to β-estradiol and sodium selenite.In conclusion, our data provide evidence that SNPs in SEPP1 and GPX1 modulate risk of BC and that eGPx activity is modified by SNPs in SEPP1, GPX4 and GPX1 and by estrogens. Our data thus suggest a role of selenoproteins in BC development
Pleistocene slope, shallow-marine and continental deposits of eastern central Italy wedge-top basin: a record of sea-level changes and mountain building.
This guidebook to Pleistocene sediments exposed in eastern central Italy has been prepared for the PRE-3 geological field trip accompanying the XXI INQUA Congress held in Rome, Italy, in July 2023. It is designed to provide an overview of the sedimentological features, stratigraphic architecture and basin evolutionary steps during the Pleistocene of the central portion of the Periadriatic basin (Central Periadriatic Basin), a N-S oriented foreland basin system associated to the Central Apennine Outer Orogenic Wedge. The Central Periadriatic Basin stretches along the Marche and Abruzzo regions and is an excellent example of an evolving mountain chain and associated deep-marine to fluvial-alluvial foredeep and wedge-top basin system. By integrating surface and subsurface datasets, this field trip affords a fine west to east transect through the Pleistocene basin-fill in southern Marche, where exposures allow a close examination of sedimentary facies and architecture of depositional systems. The basinfill succession includes coarse-grained submarine canyon-fills encased in slope mudstones, mixed beachface-shoreface conglomerates and sandstones, and alternating conglomerate and mudstone bodies interpreted as fluvial-channel and floodplain deposits, respectively. The analysis of facies architecture and discontinuity surfaces will allow the attendees to understand the relative role of sea-level changes, sediment supply, and thrust front propagation inside the foreland basins system as several factors controlling the stratigraphic record
- …
