669 research outputs found
On Invariant Structures of Black Hole Charges
We study "minimal degree" complete bases of duality- and "horizontal"-
invariant homogeneous polynomials in the flux representation of two-centered
black hole solutions in two classes of D=4 Einstein supergravity models with
symmetric vector multiplets' scalar manifolds. Both classes exhibit an SL(2,R)
"horizontal" symmetry. The first class encompasses N=2 and N=4 matter-coupled
theories, with semi-simple U-duality given by SL(2,R) x SO(m,n); the analysis
is carried out in the so-called Calabi-Vesentini symplectic frame (exhibiting
maximal manifest covariance) and until order six in the fluxes included. The
second class, exhibiting a non-trivial "horizontal" stabilizer SO(2), includes
N=2 minimally coupled and N=3 matter coupled theories, with U-duality given by
the pseudo-unitary group U(r,s) (related to complex flux representations).
Finally, we comment on the formulation of special Kaehler geometry in terms of
"generalized" groups of type E7.Comment: 1+24 pages; 1 Table. v2 : Eqs. (1.2) and (1.3) added; Eq. (2.87)
change
Fake supersymmetry versus Hamilton-Jacobi
We explain when the first-order Hamilton-Jacobi equations for black holes
(and domain walls) in (gauged) supergravity, reduce to the usual first-order
equations derived from a fake superpotential. This turns out to be equivalent
to the vanishing of a newly found constant of motion and we illustrate this
with various examples. We show that fake supersymmetry is a necessary condition
for having physically sensible extremal black hole solutions. We furthermore
observe that small black holes become scaling solutions near the horizon. When
combined with fake supersymmetry, this leads to a precise extension of the
attractor mechanism to small black holes: The attractor solution is such that
the scalars move on specific curves, determined by the black hole charges, that
are purely geodesic, although there is a non-zero potential.Comment: 20 pages, v2: Typos corrected, references adde
The mu problem and sneutrino inflation
We consider sneutrino inflation and post-inflation cosmology in the singlet
extension of the MSSM with approximate Peccei-Quinn(PQ) symmetry, assuming that
supersymmetry breaking is mediated by gauge interaction. The PQ symmetry is
broken by the intermediate-scale VEVs of two flaton fields, which are
determined by the interplay between radiative flaton soft masses and higher
order terms. Then, from the flaton VEVs, we obtain the correct mu term and the
right-handed(RH) neutrino masses for see-saw mechanism. We show that the RH
sneutrino with non-minimal gravity coupling drives inflation, thanks to the
same flaton coupling giving rise to the RH neutrino mass. After inflation,
extra vector-like states, that are responsible for the radiative breaking of
the PQ symmetry, results in thermal inflation with the flaton field, solving
the gravitino problem caused by high reheating temperature. Our model predicts
the spectral index to be n_s\simeq 0.96 due to the additional efoldings from
thermal inflation. We show that a right dark matter abundance comes from the
gravitino of 100 keV mass and a successful baryogenesis is possible via
Affleck-Dine leptogenesis.Comment: 27 pages, no figures, To appear in JHE
Inflation and dark matter in two Higgs doublet models
We consider the Higgs inflation in the extension of the Standard Model with
two Higgs doublets coupled to gravity non-minimally. In the presence of an
approximate global U(1) symmetry in the Higgs sector, both radial and angular
modes of neutral Higgs bosons drive inflation where large non-Gaussianity is
possible from appropriate initial conditions on the angular mode. We also
discuss the case with single-field inflation for which the U(1) symmetry is
broken to a Z_2 subgroup. We show that inflationary constraints, perturbativity
and stability conditions restrict the parameter space of the Higgs quartic
couplings at low energy in both multi- and single-field cases. Focusing on the
inert doublet models where Z_2 symmetry remains unbroken at low energy, we show
that the extra neutral Higgs boson can be a dark matter candidate consistent
with the inflationary constraints. The doublet dark matter is always heavy in
multi-field inflation while it can be light due to the suppression of the
co-annihilation in single-field inflation. The implication of the extra quartic
couplings on the vacuum stability bound is also discussed in the light of the
recent LHC limits on the Higgs mass.Comment: (v1) 28 pages, 8 figures; (v2) 29 pages, a new subsection 3.3 added,
references added and typos corrected, to appear in Journal of High Energy
Physic
Creation of Matter in the Universe and Groups of Type E7
We relate the mechanism of matter creation in the universe after inflation to
a simple and universal mathematical property of extended N > 1 supergravities
and related compactifications of superstring theory. We show that in all such
models, the inflaton field may decay into vector fields due to a nonminimal
scalar-vector coupling. This coupling is compulsory for all scalars except N=2
hyperscalars. The proof is based on the fact that all extended supergravities
described by symmetric coset spaces G/H have duality groups G of type E7, with
exception of U(p,n) models. For N=2 we prove separately that special geometry
requires a non-minimal scalar-vector coupling. Upon truncation to N=1
supergravity, extended models generically preserve the non-minimal
scalar-vector coupling, with exception of U(p,n) models and hyperscalars. For
some string theory/supergravity inflationary models, this coupling provides the
only way to complete the process of creation of matter in the early universe.Comment: 15 pages, 2 table
DWSB in heterotic flux compactifications
We address the construction of non-supersymmetric vacua in heterotic
compactifications with intrinsic torsion and background fluxes. In particular,
we implement the approach of domain-wall supersymmetry breaking (DWSB)
previously developed in the context of type II flux compactifications. This
approach is based on considering backgrounds where probe NS5-branes wrapping
internal three-cycles and showing up as four-dimensional domain-walls do not
develop a BPS bound, while all the other BPS bounds characterizing the N=1
supersymmetric compactifications are preserved at tree-level. Via a scalar
potential analysis we provide the conditions for these backgrounds to solve the
ten-dimensional equations of motion including order \alpha' corrections. We
also consider backgrounds where some of the NS5-domain-walls develop a BPS
bound, show their relation to no-scale SUSY-breaking vacua and construct
explicit examples via elliptic fibrations. Finally, we consider backgrounds
with a non-trivial gaugino condensate and discuss their relation to
supersymmetric and non-supersymmetric vacua in the present context.Comment: 56 pages, 1 figur
Vascular Endothelial Growth Factor (VEGF) isoform expression and activity in human and murine lung injury
<p>Abstract</p> <p>Background</p> <p>The properties of vascular endothelial growth factor (VEGF) as a potent vascular permogen and mitogen have led to investigation of its potential role in lung injury. Alternate spliced VEGF transcript generates several isoforms with potentially differing functions. The purpose of this study was to determine VEGF isoform expression and source in normal and ARDS subjects and investigate the expression and regulation of VEGF isoforms by human alveolar type 2 (ATII) cells.</p> <p>Methods</p> <p>VEGF protein expression was assessed immunohistochemically in archival normal and ARDS human lung tissue. VEGF isoform mRNA expression was assessed in human and murine lung tissue. Purified ATII cells were cultured with proinflammatory cytokines prior to RNA extraction/cell supernatant sampling/proliferation assay.</p> <p>Measurements and Main Results</p> <p>VEGF was expressed on alveolar epithelium, vascular endothelium and alveolar macrophages in normal and ARDS human lung tissue. Increases in VEGF expression were detected in later ARDS in comparison to both normal subjects and early ARDS (p < 0.001). VEGF<sub>121</sub>, VEGF<sub>165 </sub>and VEGF<sub>189 </sub>isoform mRNA expression increased in later ARDS (p < 0.05). The ratio of soluble to cell-associated isoforms was lower in early ARDS than normal subjects and later ARDS and also in murine lung injury. ATII cells constitutionally produced VEGF<sub>165 </sub>and VEGF<sub>121 </sub>protein which was increased by LPS (p < 0.05). VEGF<sub>165 </sub>upregulated ATII cell proliferation (p < 0.001) that was inhibited by soluble VEGF receptor 1 (<it>sflt</it>) (p < 0.05).</p> <p>Conclusion</p> <p>These data demonstrate that changes in VEGF isoform expression occur in ARDS which may be related to their production by and mitogenic effect on ATII cells; with potentially significant clinical consequences.</p
The integrated action framework of Rete Natura 2000 Basilicata
Basilicata Natura 2000 network consists of 50 Sites of Community Importance (SCI) and 17 Special Protection Zones (SPZs), covering alltogether more than 17% of the regional area. This network, partially overlapping other forms of land protection, represents a valuable environmental, agricultural and cultural heritage, in which the safeguard of natural resources and landscapes has to be coupled with the needs of the local population; especially in relation to development and social welfare.
The Natura 2000 project involved a panel of experts belonging to 15 different institutions, to form a steering committee with the following professional and scientific skills: vegetation, landscape, fauna, geology, agriculture, forestry, sea, architecture and planning, territorial analysis and representation. Along the 4 years project, the steering committee designed and coordinated the activities of over 150 professionals, mostly from Basilicata, who carried out field surveys and data analysis aimed at assessing the environmental conditions in the SCI and SPZs, proposing measures and plans, implementing thematic databases.
SCI/SPZ management plans, by themselves, may not be sufficient to fulfill the requirements of an effective environmental policy, which has to go along with the awareness of people, citizens and local administrators about the instances of a sustainable policy. For this reason, the activities of surveying and management have been coupled with a communication project that involves all the experts and a relevant part of professionals who participated to the Natura 2000 project. The communication activity implies the use and the creation of several tools (publishing, video, websites, meetings, photo contests, social networks ...) targeted to different groups: policy makers (local, regional, national, European ), organizations, citizens, schools, farmers, small and medium enterprises (www.natura2000basilicata.it).
A further goal is to feature the environmental highlights of Basilicata which are linked to a specific and often surprising integration of an ancient human presence with the natural elements, and the role performed by the traditional farming activities in the maintenance of ecosystem dynamics and services (in particular with agriculture). In fact, a good number of Natura 2000 sites can be considered High Nature Value Farmlands (HNVF, sensu E. Andersen, 2003), in which a virtuous relationship was established a long time ago between traditional practices and the environment itself. In this context, it combines the convergence between the activities carried on the Natura 2000 network and the project Agrival (http://utagri.enea.it/projects/agrival), a research project led by ENEA in Val d'Agri, in order to experimentally contribute to the methodology for the identification of the High Nature Value Farmlands and make them cohabit with the other economic activities in the local context.
The process started with the project Basilicata Natura 2000 Network is therefore an interesting methodological model that, in coherence with the financial planning of the European Community for the period 2014-2020 (Brussels, 12.12.2011, COMM. 874) puts together projects on environmental issues to boost the meeting of agricultural, environmental, cultural and productive policies, fostered by the EC, and enhancing the implementation of the "Prioritized Actions Frameworks" (PAF), pointed out by the European Commission as the optimal tools for the management of Natura 2000 networks
A randomized two arm phase III study in patients post radical resection of liver metastases of colorectal cancer to investigate bevacizumab in combination with capecitabine plus oxaliplatin (CAPOX) vs CAPOX alone as adjuvant treatment
<p>Abstract</p> <p>Background</p> <p>About 50% of patients with colorectal cancer are destined to develop hepatic metastases. Radical resection is the most effective treatment for patients with colorectal liver metastases offering five year survival rates between 36-60%. Unfortunately only 20% of patients are resectable at time of presentation. Radiofrequency ablation is an alternative treatment option for irresectable colorectal liver metastases with reported 5 year survival rates of 18-30%. Most patients will develop local or distant recurrences after surgery, possibly due to the outgrowth of micrometastases present at the time of liver surgery. This study aims to achieve an improved disease free survival for patients after resection or resection combined with RFA of colorectal liver metastases by adding the angiogenesis inhibitor bevacizumab to an adjuvant regimen of CAPOX.</p> <p>Methods/design</p> <p>The Hepatica study is a two-arm, multicenter, randomized, comparative efficacy and safety study. Patients are assessed no more than 8 weeks before surgery with CEA measurement and CT scanning of the chest and abdomen. Patients will be randomized after resection or resection combined with RFA to receive CAPOX and Bevacizumab or CAPOX alone. Adjuvant treatment will be initiated between 4 and 8 weeks after metastasectomy or resection in combination with RFA. In both arms patients will be assessed for recurrence/new occurrence of colorectal cancer by chest CT, abdominal CT and CEA measurement. Patients will be assessed after surgery but before randomization, thereafter every three months after surgery in the first two years and every 6 months until 5 years after surgery. In case of a confirmed recurrence/appearance of new colorectal cancer, patients can be treated with surgery or any subsequent line of chemotherapy and will be followed for survival until the end of study follow up period as well. The primary endpoint is disease free survival. Secondary endpoints are overall survival, safety and quality of life.</p> <p>Conclusion</p> <p>The HEPATICA study is designed to demonstrate a disease free survival benefit by adding bevacizumab to an adjuvant regime of CAPOX in patients with colorectal liver metastases undergoing a radical resection or resection in combination with RFA.</p> <p>Trial Registration</p> <p>ClinicalTrials.gov Identifier NCT00394992</p
The role of the bronchial microvasculature in the airway remodelling in asthma and COPD
In recent years, there has been increased interest in the vascular component of airway remodelling in chronic bronchial inflammation, such as asthma and COPD, and in its role in the progression of disease. In particular, the bronchial mucosa in asthmatics is more vascularised, showing a higher number and dimension of vessels and vascular area. Recently, insight has been obtained regarding the pivotal role of vascular endothelial growth factor (VEGF) in promoting vascular remodelling and angiogenesis. Many studies, conducted on biopsies, induced sputum or BAL, have shown the involvement of VEGF and its receptors in the vascular remodelling processes. Presumably, the vascular component of airway remodelling is a complex multi-step phenomenon involving several mediators. Among the common asthma and COPD medications, only inhaled corticosteroids have demonstrated a real ability to reverse all aspects of vascular remodelling. The aim of this review was to analyze the morphological aspects of the vascular component of airway remodelling and the possible mechanisms involved in asthma and COPD. We also focused on the functional and therapeutic implications of the bronchial microvascular changes in asthma and COPD
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