The contrasting physiological and subjective effects of chewing gum on social stress

Uncertainty exists with respect to the extent to which chewing gum may attenuate stress-induced rises in cortisol secretion (Scholey et al., 2009; Smith, 2010; Johnson et al., 2011). The present study used the Trier Social Stress Task (TSST: Kirschbaum et al., 1993), a task known to elevate cortisol secretion (Kudielka et al., 2004), in order to examine the moderating physiological and subjective effects of chewing gum on social stress. Forty participants completed the TSST either with or without chewing gum. As expected, completion of the TSST elevated both cortisol and subjective stress levels, whilst impairing mood. Although gum moderated the perception of stress, cortisol concentrations were higher following the chewing of gum. The findings are consistent with Smith (2010) who argued that elevations in cortisol following the chewing of gum reflect heightened arousal. The findings suggest that chewing gum only benefits subjective measures of stress. The mechanism remains unclear; however, this may reflect increased cerebral blood flow, cognitive distraction, and/or effects secondary to task facilitation

Combination therapy with tranilast and angiotensin-converting enzyme inhibition provides additional renoprotection in the remnant kidney model

Despite current therapy with agents that block the renin–angiotensin system, renal dysfunction continues to progress in a significant proportion of patients with kidney disease. Several pre-clinical studies have reported beneficial effects of tranilast, an inhibitor of transforming growth factor (TGF)-β's actions in a range of diseases that are characterized by fibrosis. However, whether such therapy provides additional benefits in renal disease, when added to angiotensin-converting enzyme (ACE) inhibition, has not been explored. We randomized subtotally (5/6) nephrectomized rats to receive vehicle, the ACE inhibitor, perindopril (6 mg/l), tranilast (400 mg/kg/day), or their combination for 12 weeks. When compared with sham-nephrectomized animals, subtotally nephrectomized animals had reduced creatinine clearance, proteinuria, glomerulosclerosis, interstitial fibrosis, tubular atrophy, and evidence of TGF-β activity, as indicated by the abundant nuclear staining of phosphorylated Smad2. These manifestations of injury and TGF-β activation were all attenuated by treatment with either tranilast or perindopril, with the latter also attenuating the animals’ hypertension. When compared with single-agent treatment, the combination of tranilast and perindopril provided additional, incremental improvements in creatinine clearance, proteinuria, and glomerulosclerosis, and a reduction in nuclear phsopho-Smad2 beyond single-agent treatment. These findings indicate that the combination of tranilast and perindopril was superior to single-agent treatment on kidney structure and function in the remnant kidney model, and suggests the potential for such dual therapy in kidney disease that continues to progress despite blockade of the renin–angiotensin system

Initial Conditions for Models of Dynamical Systems

The long-time behaviour of many dynamical systems may be effectively predicted by a low-dimensional model that describes the evolution of a reduced set of variables. We consider the question of how to equip such a low-dimensional model with appropriate initial conditions, so that it faithfully reproduces the long-term behaviour of the original high-dimensional dynamical system. Our method involves putting the dynamical system into normal form, which not only generates the low-dimensional model, but also provides the correct initial conditions for the model. We illustrate the method with several examples. Keywords: normal form, isochrons, initialisation, centre manifoldComment: 24 pages in standard LaTeX, 66K, no figure

Capturing Model Risk and Rating Momentum in the Estimation of Probabilities of Default and Credit Rating Migrations

We present two methodologies on the estimation of rating transition probabilities within Markov and non-Markov frameworks. We first estimate a continuous-time Markov chain using discrete (missing) data and derive a simpler expression for the Fisher information matrix, reducing the computational time needed for the Wald confidence interval by a factor of a half. We provide an efficient procedure for transferring such uncertainties from the generator matrix of the Markov chain to the corresponding rating migration probabilities and, crucially, default probabilities. For our second contribution, we assume access to the full (continuous) data set and propose a tractable and parsimonious self-exciting marked point processes model able to capture the non-Markovian effect of rating momentum. Compared to the Markov model, the non-Markov model yields higher probabilities of default in the investment grades, but also lower default probabilities in some speculative grades. Both findings agree with empirical observations and have clear practical implications. We illustrate all methods using data from Moody's proprietary corporate credit ratings data set. Implementations are available in the R package ctmcd.Comment: 22 pages, 5 Figures, 4 Tables. To Appear in Quantitative Financ

Magnon diffusion lengths in bulk and thin film Fe3O4 for spin Seebeck applications

The magnon diffusion length (MDL) is understood to play a major role in the thickness dependence of spin Seebeck effect (SSE) voltages in Fe3O4/Pt thin films. Here we extract the MDL in an Fe3O4 single crystal using inelastic neutron scattering (INS) and in Fe3O4/Pt thin films using accurate heat flux SSE and static magnetization measurements. The INS MDLs were 34 ± 8 nm at 300 K and 27 ± 6 nm at 50 K. The SSE MDLs decreased with temperature (19 ± 2 nm at 300 K and 13 ± 4 nm at 50 K), but were markedly smaller. Whilst the bulk MDL is expected to be an upper limit of the MDL in thin films, we show that the film magnetization must be considered to obtain MDLs from SSE measurements. This study highlights the importance of disentangling the role of various effects in SSE measurements which is crucial in increasing the efficiencies of thermomagnetic energy harvesting devices

Incursion of meteoric waters into the ductile regime in an active orogen

Rapid tectonic uplift on the Alpine Fault, New Zealand, elevates topography, regional geothermal gradients, and the depth to the brittle ductile transition, and drives fluid flow that influences deformation and mineralisation within the orogen. Oxygen and hydrogen stable isotopes, fluid inclusion and Fourier Transform Infrared (FT-IR) analyses of quartz from veins which formed at a wide range of depths, temperatures and deformation regimes identify fluid sources and the depth of penetration of meteoric waters. Most veins formed under brittle conditions and with isotope signatures (δ18OH2O = −9.0 to +8.7‰VSMOW and ‰ ) indicative of progressively rock-equilibrated meteoric waters. Two generations of quartz veins that post-date mylonitic foliation but endured further ductile deformation, and hence formation below the brittle to ductile transition zone ( depth), preserve included hydrothermal fluids with values between −84 and ‰ , indicating formation from meteoric waters. FT-IR analyses of these veins show no evidence of structural hydrogen release, precluding this as a source of low values. In contrast, the oxygen isotopic signal of these fluids has almost completely equilibrated with host rocks (δ18OH2O = +2.3 to +8.7‰). These data show that meteoric waters dominate the fluid phase in the rocks, and there is no stable isotopic requirement for the presence of metamorphic fluids during the precipitation of ductilely deformed quartz veins. This requires the penetration during orogenesis of meteoric waters into and possibly below the brittle to ductile transition zone

Community Structure in Congressional Cosponsorship Networks

We study the United States Congress by constructing networks between Members of Congress based on the legislation that they cosponsor. Using the concept of modularity, we identify the community structure of Congressmen, as connected via sponsorship/cosponsorship of the same legislation, to investigate the collaborative communities of legislators in both chambers of Congress. This analysis yields an explicit and conceptually clear measure of political polarization, demonstrating a sharp increase in partisan polarization which preceded and then culminated in the 104th Congress (1995-1996), when Republicans took control of both chambers. Although polarization has since waned in the U.S. Senate, it remains at historically high levels in the House of Representatives.Comment: 8 pages, 4 figures (some with multiple parts), to appear in Physica A; additional background info and explanations added from last versio

Modified iterative versus Laplacian Landau gauge in compact U(1) theory

Compact U(1) theory in 4 dimensions is used to compare the modified iterative and the Laplacian fixing to lattice Landau gauge in a controlled setting, since in the Coulomb phase the lattice theory must reproduce the perturbative prediction. It turns out that on either side of the phase transition clear differences show up and in the Coulomb phase the ability to remove double Dirac sheets proves vital on a small lattice.Comment: 14 pages, 8 figures containing 23 graphs, v2: 2 figures removed, 2 references adde

The Ising-Kondo lattice with transverse field: an f-moment Hamiltonian for URu2Si2?

We study the phase diagram of the Ising-Kondo lattice with transverse magnetic field as a possible model for the weak-moment heavy-fermion compound URu2Si2, in terms of two low-lying f singlets in which the uranium moment is coupled by on-site exchange to the conduction electron spins. In the mean-field approximation for an extended range of parameters, we show that the conduction electron magnetization responds logarithmically to f-moment formation, that the ordered moment in the antiferromagnetic state is anomalously small, and that the Neel temperature is of the order observed. The model gives a qualitatively correct temperature-dependence, but not magnitude, of the specific heat. The majority of the specific heat jump at the Neel temperature arises from the formation of a spin gap in the conduction electron spectrum. We also discuss the single-impurity version of the model and speculate on ways to increase the specific heat coefficient. In the limits of small bandwidth and of small Ising-Kondo coupling, we find that the model corresponds to anisotropic Heisenberg and Hubbard models respectively.Comment: 20 pages RevTeX including 5 figures (1 in LaTeX, 4 in uuencoded EPS), Received by Phys. Rev. B 19 April 199

The impact of self-efficacy, expectations, and readiness on hearing aid outcomes

Objective: To examine the impact of self-efficacy and expectations for hearing aids, and readiness to improve hearing, on hearing aid outcome measures in first-time adult hearing aid users Design: A prospective, single centre design. Predictor variables measured at the hearing assessment included measures of self-efficacy, expectations and readiness to improve hearing. Outcome measures obtained at sixweek follow-up were the Glasgow Hearing Aid Benefit Profile and Satisfaction with Amplification in Daily Life. Study sample: A sample of 30 first-time adult hearing aid users were recruited through a public-sector funded audiology clinic. Results: When measured prior to hearing aid fitting, self-efficacy for hearing aids predicted satisfaction with hearing aids but was not related to other hearing aid outcomes. Expectations of hearing aids, in particular positive expectations, and readiness to improve hearing predicted outcomes for hearing aid satisfaction and benefit, although not hearing aid use. Hearing sensitivity was not correlated with hearing aid outcomes. Conclusions: These results suggest that assessment of expectations of hearing aids, and readiness to improve hearing, may be useful to help identify individuals attending audiology clinics who would most likely benefit from hearing aid provision