3,759 research outputs found
Forecasts of the Scottish economy [March 2013]
After two quarters of negative growth, the Scottish economy delivered a strong performance in the third quarter of 2012. The UK economy as a whole saw negative growth in the final quarter of 2012 - and it looks likely that Scottish growth over 2012 will be close to zero. Over the coming year, we see slowing earnings growth, the introduction of welfare changes and continued fiscal consolidation weakening the domestic economy, while there could be increasing volatility, including potentially critical political shocks, in important export markets. The net result is a lowering of our central growth forecasts for 2013 and 2014. It continues to be true that risks are aligned to the downside again. Growth in the United States â Scotland's single largest export market â appears strong, highlighting opportunities, albeit further concentrating Scottish reliance on this market
Dispersive photoluminescence decay by geminate recombination in amorphous semiconductors
The photoluminescence decay in amorphous semiconductors is described by power
law at long times. The power-law decay of photoluminescence at
long times is commonly observed but recent experiments have revealed that the
exponent, , is smaller than the value 1.5 predicted from a
geminate recombination model assuming normal diffusion. Transient currents
observed in the time-of-flight experiments are highly dispersive characterized
by the disorder parameter smaller than 1. Geminate recombination rate
should be influenced by the dispersive transport of charge carriers. In this
paper we derive the simple relation, . Not only the
exponent but also the amplitude of the decay calculated in this study is
consistent with measured photoluminescence in a-Si:H.Comment: 18pages. Submitted for the publication in Phys. Rev.
The Small Observed Baryon Asymmetry from a Large Lepton Asymmetry
Primordial Big-Bang Nucleosynthesis (BBN) tightly constrains the existence of
any additional relativistic degrees of freedom at that epoch. However a large
asymmetry in electron neutrino number shifts the chemical equilibrium between
the neutron and proton at neutron freeze-out and allows such additional
particle species. Moreover, the BBN itself may also prefer such an asymmetry to
reconcile predicted element abundances and observations. However, such a large
asymmetry appears to be in conflict with the observed small baryon asymmetry if
they are in sphaleron mediated equilibrium. In this paper we point out the
surprising fact that in the Standard Model, if the asymmetries in the electron
number and the muon number are equal (and opposite) and of the size required to
reconcile BBN theory with observations, a baryon asymmetry of the Universe of
the correct magnitude and sign is automatically generated within a factor of
two. This small remaining discrepancy is naturally remedied in the
supersymmetric Standard Model.Comment: 14 page
Dynamical (Super)Symmetry Breaking
Dynamical Symmetry Breaking (DSB) is a concept theorists rely on very often in the discussions of strong dynamics, model building, and hierarchy problems. In this talk, I will discuss why this is such a permeating concept among theorists and how they are used in understanding physics. I also briefly review recent progress in using dynamical symmetry breaking to construct models of supersymmetry breaking and fermion masses
Impurity effects at finite temperature in the two-dimensional S=1/2 Heisenberg antiferromagnet
We discuss effects of various impurities on the magnetic susceptibility and
the specific heat of the quantum S=1/2 Heisenberg antiferromagnet on a
two-dimensional square lattice. For impurities with spin S_i > 0 (here S_i=1/2
in the case of a vacancy or an added spin, and S_i=1 for a spin coupled
ferromagnetically to its neighbors), our quantum Monte Carlo simulations
confirm a classical-like Curie susceptibility contribution S_i^2/4T, which
originates from an alignment of the impurity spin with the local N\'eel order.
In addition, we find a logarithmically divergent contribution, which we
attribute to fluctuations transverse to the local N\'eel vector. We also study
frustrated and nonfrustrated bond impurities with S_i=0. For a simple intuitive
picture of the impurity problem, we discuss an effective few-spin model that
can distinguish between the different impurities and reproduces the
leading-order simulation data over a wide temperature range.Comment: 15 pages, 14 figures, submitted to PRB. v2, published version with
cosmetic change
Quark mass uncertainties revive KSVZ axion dark matter
The Kaplan-Manohar ambiguity in light quark masses allows for a larger
uncertainty in the ratio of up to down quark masses than naive estimates from
the chiral Lagrangian would indicate. We show that it allows for a relaxation
of experimental bounds on the QCD axion, specifically KSVZ axions in the eV mass range composing 100% of the galactic dark matter halo can evade the
experimental limits placed by the ADMX collaboration.Comment: 9 pages, 5 figure
Randall-Sundrum graviton spin determination using azimuthal angular dependence
Quantum interference of helicity amplitudes provides a powerful tool for
measuring the spins of new particles. By looking at the azimuthal angular
dependence of the differential cross-section in the production followed by
decay of a new particle species one can determine its spin by looking at the
various cosine modes. The heavy spin-2 Kaluza-Klein (KK) graviton provides a
unique signature with a mode. We study the feasibility of this
approach to measuring the spin of the KK graviton in the Randall-Sundrum Model
at the LHC.Comment: 7 pages, 6 figure
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Complete recovery from anxiety disorders following Cognitive Behavioural Therapy in children and adolescents: a meta analysis
Cognitive Behavior Therapy (CBT) is a well-established treatment for childhood anxiety disorders. Meta-analyses have concluded that approximately 60% of children recover following treatment, however these include studies using a broad range of diagnostic indices to assess outcomes including whether children are free of the one anxiety disorder that causes most interference (i.e. the primary anxiety disorder) or whether children are free of all anxiety disorders. We conducted a meta-analysis to establish the efficacy of CBT in terms of absence of all anxiety disorders. Where available we compared this rate to outcomes based on absence of primary disorder. Of 56 published randomized controlled trials, 19 provided data on recovery from all anxiety disorders (n = 635 CBT, n = 450 control participants). There was significant heterogeneity across those studies with available data and full recovery rates varied from 47.6 to 66.4% among children without autistic spectrum conditions (ASC) and 12.2 to 36.7% for children with ASC following treatment, compared to up to 20.6% and 21.3% recovery in waitlist and active treatment comparisons. The lack of consistency in diagnostic outcomes highlights the urgent need for consensus on reporting in future RCTs of childhood anxiety disorders for the meaningful synthesis of data going forwards
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