417 research outputs found
Surviving Unemployment without State Support: Unemployment and Household Formation in South Africa
High unemployment in many OECD countries is often attributed, at least in part, to the generosity and long duration of unemployment compensation. It is therefore instructive to examine a country where high unemployment exists despite the near complete absence of an unemployment insurance system. In South Africa unemployment stood at 23% in 1997 and the unemployed have no unemployment insurance nor informal sector activities to fall back on. This paper examines how the unemployed are able to get access to resources without support from unemployment compensation. Analysing a household survey from 1995, we find that the household formation response of the unemployed is the critical way in which they assure access to resources. In particular, unemployment delays the setting up of an individual household of young people, in some cases by decades. It also leads to the dissolution of existing households and a return of constituent members to parents and other relatives and friends. Access to state transfers (in particular, nonÂĄ contributory old age pensions) increases the likelihood of attracting unemployed persons to a household. Some unemployed do not benefit from this safety net, and the presence of unemployed members pulls many households supporting them into poverty. We also show that the household formation responses draw some unemployed away from employment opportunities and thus lowers their employment prospects. The paper discusses the implications of these findings for debates about unemployment and social policy in South Africa and in OECD countries
Sfermion Pair Production in Polarized and Unpolarized Collisions
We calculate total and differential cross sections for the production of
sfermion pairs in photon-photon collisions, including contributions from
resolved photons and arbitrary photon polarization. Sfermion production in
photon collisions depends only on the sfermion mass and charge. It is thus
independent of the details of the SUSY breaking mechanism, but highly sensitive
to the sfermion charge. We compare the total cross sections for bremsstrahlung,
beamstrahlung, and laser backscattering photons to those in
annihilation. We find that the total cross section at a polarized photon
collider is larger than the annihilation cross section up to the
kinematic limit of the photon collider.Comment: 19 pages, Latex, 18 (e)ps-figure
The Physics of Ultraperipheral Collisions at the LHC
We discuss the physics of large impact parameter interactions at the LHC:
ultraperipheral collisions (UPCs). The dominant processes in UPCs are
photon-nucleon (nucleus) interactions. The current LHC detector configurations
can explore small hard phenomena with nuclei and nucleons at photon-nucleon
center-of-mass energies above 1 TeV, extending the range of HERA by a
factor of ten. In particular, it will be possible to probe diffractive and
inclusive parton densities in nuclei using several processes. The interaction
of small dipoles with protons and nuclei can be investigated in elastic and
quasi-elastic and production as well as in high
production accompanied by a rapidity gap. Several of these phenomena
provide clean signatures of the onset of the new high gluon density QCD regime.
The LHC is in the kinematic range where nonlinear effects are several times
larger than at HERA. Two-photon processes in UPCs are also studied. In
addition, while UPCs play a role in limiting the maximum beam luminosity, they
can also be used a luminosity monitor by measuring mutual electromagnetic
dissociation of the beam nuclei. We also review similar studies at HERA and
RHIC as well as describe the potential use of the LHC detectors for UPC
measurements.Comment: 229 Pages, 121 figure
High-precision measurements from LHC to FCC-ee
This document provides a writeup of all contributions to the workshop on
"High precision measurements of : From LHC to FCC-ee" held at CERN,
Oct. 12--13, 2015. The workshop explored in depth the latest developments on
the determination of the QCD coupling from 15 methods where high
precision measurements are (or will be) available. Those include low-energy
observables: (i) lattice QCD, (ii) pion decay factor, (iii) quarkonia and (iv)
decays, (v) soft parton-to-hadron fragmentation functions, as well as
high-energy observables: (vi) global fits of parton distribution functions,
(vii) hard parton-to-hadron fragmentation functions, (viii) jets in p
DIS and -p photoproduction, (ix) photon structure function in
-, (x) event shapes and (xi) jet cross sections in
collisions, (xii) W boson and (xiii) Z boson decays, and (xiv) jets and (xv)
top-quark cross sections in proton-(anti)proton collisions. The current status
of the theoretical and experimental uncertainties associated to each extraction
method, the improvements expected from LHC data in the coming years, and future
perspectives achievable in collisions at the Future Circular Collider
(FCC-ee) with (1--100 ab) integrated luminosities yielding
10 Z bosons and jets, and 10 W bosons and leptons, are
thoroughly reviewed. The current uncertainty of the (preliminary) 2015 strong
coupling world-average value, = 0.1177 0.0013, is about
1\%. Some participants believed this may be reduced by a factor of three in the
near future by including novel high-precision observables, although this
opinion was not universally shared. At the FCC-ee facility, a factor of ten
reduction in the uncertainty should be possible, mostly thanks to
the huge Z and W data samples available.Comment: 135 pages, 56 figures. CERN-PH-TH-2015-299, CoEPP-MN-15-13. This
document is dedicated to the memory of Guido Altarell
Plasmacytoid dendritic cells of melanoma patients present exogenous proteins to CD4+ T cells after FcÎłRII-mediated uptake
Plasmacytoid dendritic cells (pDCs) contribute to innate antiviral immune responses by producing type I interferons. Although human pDCs can induce T cell responses upon viral infection, it remains unclear if pDCs can present exogenous antigens. Here, we show that human pDCs exploit FcÎłRII (CD32) to internalize antigenâantibody complexes, resulting in the presentation of exogenous antigen to T cells. pDCs isolated from melanoma patients vaccinated with autologous monocyte-derived peptide- and keyhold limpet hemocyanin (KLH)âloaded dendritic cells, but not from nonvaccinated patients or patients that lack a humoral response against KLH, were able to stimulate KLH-specific T cell proliferation. Interestingly, we observed that internalization of KLH by pDCs depended on the presence of serum from vaccinated patients that developed an anti-KLH antibody response. Anti-CD32 antibodies inhibited antigen uptake and presentation, demonstrating that circulating anti-KLH antibodies binding to CD32 mediate KLH internalization. We conclude that CD32 is an antigen uptake receptor on pDCs and that antigen presentation by pDCs is of particular relevance when circulating antibodies are present. Antigen presentation by pDCs may thus modulate the strength and quality of the secondary phase of an immune response
What do general practitioners know about ADHD? Attitudes and knowledge among first-contact gatekeepers: systematic narrative review
Background: Attention Deficit Hyperactivity Disorder (ADHD) is a common childhood disorder with international prevalence estimates of 5 % in childhood, yet significant evidence exists that far fewer children receive ADHD services. In many countries, ADHD is assessed and diagnosed in specialist mental health or neuro-developmental paediatric clinics, to which referral by General (Family) Practitioners (GPs) is required. In such âgatekeeperâ settings, where GPs act as a filter to diagnosis and treatment, GPs may either not recognise potential ADHD cases, or may be reluctant to refer. This study systematically reviews the literature regarding GPsâ views of ADHD in such settings.
Methods: A search of nine major databases was conducted, with wide search parameters; 3776 records were initially retrieved. Studies were included if they were from settings where GPs are typically gatekeepers to ADHD services; if they addressed GPsâ ADHD attitudes and knowledge; if methods were clearly described; and if results for GPs were reported separately from those of other health professionals.
Results: Few studies specifically addressed GP attitudes to ADHD. Only 11 papers (10 studies), spanning 2000â2010, met inclusion criteria, predominantly from the UK, Europe and Australia. As studies varied methodologically, findings are reported as a thematic narrative, under the following themes: Recognition rate; ADHD controversy (medicalisation, stigma, labelling); Causes of ADHD; GPs and ADHD diagnosis; GPs and ADHD treatment; GP ADHD training and sources of information; and Age, sex differences in knowledge and attitudes.
Conclusions: Across times and settings, GPs practising in first-contact gatekeeper settings had mixed and often unhelpful attitudes regarding the validity of ADHD as a construct, the role of medication and how parenting contributed to presentation. A paucity of training was identified, alongside a reluctance of GPs to become involved in shared care practice. If access to services is to be improved for possible ADHD cases, there needs to be a focused and collaborative approach to training
Giant QCD K-factors beyond NLO
Hadronic observables in Z+jet events can be subject to large NLO corrections
at TeV scales, with K-factors that even reach values of order 50 in some cases.
We develop a method, LoopSim, by which approximate NNLO predictions can be
obtained for such observables, supplementing NLO Z+jet and NLO Z+2-jet results
with a unitarity-based approximation for missing higher loop terms. We first
test the method against known NNLO results for Drell-Yan lepton pt spectra. We
then show our approximate NNLO results for the Z+jet observables. Finally we
examine whether the LoopSim method can provide useful information even in cases
without giant K-factors, with results for observables in dijet events that can
be compared to early LHC data.Comment: 38 pages, 13 figures; v2 includes additional reference
Parton Distributions Working Group
The main focus of this working group was to investigate the different issues
associated with the development of quantitative tools to estimate parton
distribution functions uncertainties. In the conclusion, we introduce a
"Manifesto" that describes an optimal method for reporting data.Comment: Report of the Parton Distributions Working Group of the 'QCD and Weak
Boson Physics workshop in preparation for Run II at the Fermilab Tevatron'.
Co-Conveners: L. de Barbaro, S.A. Keller, S. Kuhlmann, H. Schellman, and
W.-K. Tun
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