2,420 research outputs found
Herschel/SPIRE observations of the dusty disk of NGC 4244
We present Herschel/SPIRE images at 250, 350, and 500 mu m of NGC 4244, a typical low-mass, disk-only and edge-on spiral galaxy. The dust disk is clumpy and shows signs of truncation at the break radius of the stellar disk. This disk coincides with the densest part of the Hi disk. We compare the spectral energy distribution (SED), including the new SPIRE fluxes, to 3D radiative transfer models; a smooth model disk and a clumpy model with embedded heating. Each model requires a very high value for the dust scale-length (h(d) = 2-5 h(*)), higher dust masses than previous models of NGC 4244 (M-d = 0.47-1.39 x 10(7) M-circle dot) and a face-on optical depth of tau(f.o.)(V) = 0.4-1.12, in agreement with previous disk opacity studies. The vertical scales of stars and dust are similar. The clumpy model much better mimics the general morphology in the sub-mm images and the general SED. The inferred gas-to-dust mass ratio is compatible with those of similar low-mass disks. The relatively large radial scale-length of the dust disk points to radial mixing of the dusty ISM within the stellar disk. The large vertical dust scale and the clumpy dust distribution of our SED model are both consistent with a scenario in which the vertical structure of the ISM is dictated by the balance of turbulence and self-gravity
Consistency Conditions on S-Matrix of Spin 1 Massless Particles
Motivated by new techniques in the computation of scattering amplitudes of
massless particles in four dimensions, like BCFW recursion relations, the
question of how much structure of the S-matrix can be determined from purely
S-matrix arguments has received new attention. The BCFW recursion relations for
massless particles of spin 1 and 2 imply that the whole tree-level S-matrix can
be determined in terms of three-particle amplitudes (evaluated at complex
momenta). However, the known proofs of the validity of the relations rely on
the Lagrangian of the theory, either by using Feynman diagrams explicitly or by
studying the effective theory at large complex momenta. This means that a
purely S-matrix theoretic proof of the relations is still missing. The aim of
this paper is to provide such a proof for spin 1 particles by extending the
four-particle test introduced by P. Benincasa and F. Cachazo in
arXiv:0705.4305[hep-th] to all particles. We show how n-particle tests imply
that the rational function built from the BCFW recursion relations possesses
all the correct factorization channels including holomorphic and
anti-holomorphic collinear limits. This in turn implies that they give the
correct S-matrix of the theory.Comment: 24 pages, 4 figure
On the infrared behaviour of 3d Chern-Simons theories in N=2 superspace
We discuss the problem of infrared divergences in the N=2 superspace approach
to classically marginal three-dimensional Chern-Simons-matter theories.
Considering the specific case of ABJM theory, we describe the origin of such
divergences and offer a prescription to eliminate them by introducing
non-trivial gauge-fixing terms in the action. We also comment on the extension
of our procedure to higher loop order and to general three-dimensional
Chern-Simons-matter models.Comment: 26 pages, 6 figures, JHEP3; v2: minor corrections and references
added; v3: introduction expanded, presentation of section 3.3.1 improved,
references added, version to appear in JHE
Exactly Marginal Deformations and Global Symmetries
We study the problem of finding exactly marginal deformations of N=1
superconformal field theories in four dimensions. We find that the only way a
marginal chiral operator can become not exactly marginal is for it to combine
with a conserved current multiplet. Additionally, we find that the space of
exactly marginal deformations, also called the "conformal manifold," is the
quotient of the space of marginal couplings by the complexified continuous
global symmetry group. This fact explains why exactly marginal deformations are
ubiquitous in N=1 theories. Our method turns the problem of enumerating exactly
marginal operators into a problem in group theory, and substantially extends
and simplifies the previous analysis by Leigh and Strassler. We also briefly
discuss how to apply our analysis to N=2 theories in three dimensions.Comment: 23 pages, 2 figure
Note on New KLT relations
In this short note, we present two results about KLT relations discussed in
recent several papers. Our first result is the re-derivation of Mason-Skinner
MHV amplitude by applying the S_{n-3} permutation symmetric KLT relations
directly to MHV amplitude. Our second result is the equivalence proof of the
newly discovered S_{n-2} permutation symmetric KLT relations and the well-known
S_{n-3} permutation symmetric KLT relations. Although both formulas have been
shown to be correct by BCFW recursion relations, our result is the first direct
check using the regularized definition of the new formula.Comment: 15 Pages; v2: minor correction
Budesonide foam versus budesonide enema in active ulcerative proctitis and proctosigmoiditis
Background: Rectal budesonide is an effective treatment of active ulcerative proctitis or proctosigmoiditis. Aim: To compare the therapeutic efficacy, tolerability and safety, and patient's preference of budesonide foam vs. budesonide enema. Methods: Patients with active ulcerative proctitis or proctosigmoiditis (clinical activity index >4 and endoscopic index ≥4) were eligible for this double-blind, double-dummy, randomized, multicentre study. They received 2 mg/25 mL budesonide foam and placebo enema (n = 265), or 2 mg/100 mL budesonide enema and placebo foam (n = 268) for 4 weeks. Primary endpoint was clinical remission (clinical activity index ≤4) at the final/withdrawal visit (per protocol). Results: A total of 541 patients were randomized - 533 were evaluable for intention-to-treat analysis and 449 for per protocol analysis. Clinical remission rates (per protocol) were 60% for budesonide foam and 66% for budesonide enema (P = 0.02362 for non-inferiority of foam vs. enema within a predefined non-inferiority margin of 15%). Both formulations were safe and no drug-related serious adverse events were observed. Because of better tolerability and easier application most patients preferred foam (84%). Conclusion: Budesonide foam is as effective as budesonide enema in the treatment of active ulcerative proctitis or proctosigmoiditis. Both budesonide formulations are safe, and most patients prefer foam.publishersversionPeer reviewe
Mapping and assessment of ecosystems and their services. Urban ecosystems
Action 5 of the EU Biodiversity Strategy to 2020 requires member states to Map and Assess the state of Ecosystems and their Services (MAES). This report provides guidance for mapping and assessment
of urban ecosystems. The MAES urban pilot is a collaboration between the European Commission, the European Environment Agency, volunteering Member States and cities, and stakeholders. Its ultimate
goal is to deliver a knowledge base for policy and management of urban ecosystems by analysing urban green infrastructure, condition of urban ecosystems and ecosystem services. This report presents guidance for mapping urban ecosystems and includes an indicator framework to assess the condition of urban ecosystems and urban ecosystem services. The scientific framework of mapping and assessment is designed to support in particular urban planning policy and policy on green infrastructure at urban, metropolitan and regional scales. The results are based on the following different sources of information: a literature survey of 54 scientific articles, an online-survey (on urban ecosystems, related policies and planning instruments and with participation of 42 cities), ten case studies (Portugal: Cascais, Oeiras, Lisbon; Italy: Padua, Trento, Rome; The Netherlands: Utrecht; Poland: Poznań; Spain: Barcelona; Norway: Oslo), and a two-day expert workshop. The case studies constituted the core of the MAES urban pilot. They provided real examples and applications of how mapping and assessment can be organized to support policy; on top, they provided the necessary expertise to select a set of final indicators for condition and ecosystem services. Urban ecosystems or cities are defined here as socio-ecological systems which are composed of green infrastructure and built infrastructure. Urban green infrastructure (GI) is understood in this report as the multi-functional network of urban green spaces situated within the boundary of the urban ecosystem. Urban green spaces are the structural components of urban GI.
This study has shown that there is a large scope for urban ecosystem assessments. Firstly, urban policies increasingly use urban green infrastructure and nature-based solutions in their planning process. Secondly, an increasing amount of data at multiple spatial scales is becoming available to support these policies, to provide a baseline, and to compare or benchmark cities with respect to the extent and management of the urban ecosystem. Concrete examples are given on how to delineate urban ecosystems, how to choose an appropriate spatial scale, and how to map urban ecosystems based on a combination of national or European datasets (including Urban Atlas) and locally collected information (e.g., location of trees). Also examples of typologies for urban green spaces are presented.
This report presents an indicator framework which is composed of indicators to assess for urban ecosystem condition and for urban ecosystem services. These are the result of a rigorous selection
process and ensure consistent mapping and assessment across Europe. The MAES urban pilot will continue with work on the interface between research and policy. The framework presented in this report needs to be tested and validated across Europe, e.g. on its applicability at city scale, on how far the methodology for measuring ecosystem condition and ecosystem service delivery in urban areas can be used to assess urban green infrastructure and nature-based solutions
Recommended from our members
Measurement of electrons from heavy-flavour hadron decays as a function of multiplicity in p-Pb collisions at √sNN = 5.02 TeV
The multiplicity dependence of electron production from heavy-flavour hadron decays as a function of transverse momentum was measured in p-Pb collisions at sNN = 5.02 TeV using the ALICE detector at the LHC. The measurement was performed in the centre-of-mass rapidity interval −1.07 < ycms< 0.14 and transverse momentum interval 2 < pT< 16 GeV/c. The multiplicity dependence of the production of electrons from heavy-flavour hadron decays was studied by comparing the pT spectra measured for different multiplicity classes with those measured in pp collisions (QpPb) and in peripheral p-Pb collisions (Qcp). The QpPb results obtained are consistent with unity within uncertainties in the measured pT interval and event classes. This indicates that heavy-flavour decay electron production is consistent with binary scaling and independent of the geometry of the collision system. Additionally, the results suggest that cold nuclear matter effects are negligible within uncertainties, in the production of heavy-flavour decay electrons at midrapidity in p-Pb collisions. [Figure not available: see fulltext.
Recommended from our members
Measurement of charged jet cross section in pp collisions at s =5.02 TeV
The cross section of jets reconstructed from charged particles is measured in the transverse momentum range of
On the cubic interactions of massive and partially-massless higher spins in (A)dS
Cubic interactions of massive and partially-massless totally-symmetric
higher-spin fields in any constant-curvature background of dimension greater
than three are investigated. Making use of the ambient-space formalism, the
consistency condition for the traceless and transverse parts of the
parity-invariant interactions is recast into a system of partial differential
equations. The latter can be explicitly solved for given s_1-s_2-s_3 couplings
and the 2-2-2 and 3-3-2 examples are provided in detail for general choices of
the masses. On the other hand, the general solutions for the interactions
involving massive and massless fields are expressed in a compact form as
generating functions of all the consistent couplings. The St\"uckelberg
formulation of the cubic interactions as well as their massless limits are also
analyzed.Comment: 42 pages, 2 tables, LaTex. Comments on two-derivative couplings
involving partially-massless spin-2 fields added, typos corrected, references
added. v2: final version to appear in JHEP. v3: formulae (3.4) and (3.9)
correcte
- …