States of maximum entropy production in a onedimensional vertical model with convective adjustment

We investigate the hypothesis that the atmosphere is constrained to maximize its entropy production by using a one-dimensional (1-D) vertical model. We prescribe the lapse rate in the convective layer as that of the standard troposphere. The assumption that convection sustains a critical lapse rate was absent in previous studies, which focused on the vertical distribution of climatic variables, since such a convective adjustment reduces the degrees of freedom of the system and may prevent the application of the maximum entropy production (MEP) principle. This is not the case in the radiative–convective model (RCM) developed here, since we accept a discontinuity of temperatures at the surface similar to that adopted in many RCMs. For current conditions, the MEP state gives a difference between the ground temperature and the air temperature at the surface ≈10 K. In comparison, conventional RCMs obtain a discontinuity ≈2 K only. However, the surface boundary layer velocity in the MEP state appears reasonable (≈3 m s-¹). Moreover, although the convective flux at the surface in MEP states is almost uniform in optically thick atmospheres, it reaches a maximum value for an optical thickness similar to current conditions. This additional result may support the maximum convection hypothesis suggested by Paltridge (1978)

Predicting the potential for lightning activity in mediterranean storms based on the WRF model dynamic and microphysical fields

A new parameter is introduced: the lightning potential index (LPI), which is a measure of the potential for charge generation and separation that leads to lightning flashes in convective thunderstorms. The LPI is calculated within the charge separation region of clouds between 0 C and 20 C, where the noninductive mechanism involving collisions of ice and graupel particles in the presence of supercooled water is most effective. As shown in several case studies using the Weather Research and Forecasting (WRF) model with explicit microphysics, the LPI is highly correlated with observed lightning. It is suggested that the LPI may be a useful parameter for predicting lightning as well as a tool for improving weather forecasting of convective storms and heavy rainfall.

A fully adaptive numerical approximation for a two-dimensional epidemic model with nonlinear cross-diffusion

An epidemic model is formulated by a reactionâeuro"diffusion system where the spatial pattern formation is driven by cross-diffusion. The reaction terms describe the local dynamics of susceptible and infected species, whereas the diffusion terms account for the spatial distribution dynamics. For both self-diffusion and cross-diffusion, nonlinear constitutive assumptions are suggested. To simulate the pattern formation two finite volume formulations are proposed, which employ a conservative and a non-conservative discretization, respectively. An efficient simulation is obtained by a fully adaptive multiresolution strategy. Numerical examples illustrate the impact of the cross-diffusion on the pattern formation.

The role of unions in an endogenous growth model with human capital

In this paper we study the relationship between unions and growth in a two-sector overlapping generations model with altruism and humancapital. This relationship depends on the interaction between the technology in the sector that produces human capital, the degreeof unionization of the economy and the operativeness of the bequest motive.

Comment on "Kinetics of spinodal decomposition in the ising model with vacancy diffusion"

In a recent paper [Phys. Rev. B 50, 3477 (1994)], P. Fratzl and O. Penrose present the results of the Monte Carlo simulation of the spinodal decomposition problem (phase separation) using the vacancy dynamics mechanism. They observe that the t1/3 growth regime is reached faster than when using the standard Kawasaki dynamics. In this Comment we provide a simple explanation for the phenomenon based on the role of interface diffusion, which they claim is irrelevant for the observed behavior.

Finite-size scaling analysis of the avalanches in the three-dimensional Gaussian random-field Ising model with metastable dynamics

A numerical study is presented of the third-dimensional Gaussian random-field Ising model at T=0 driven by an external field. Standard synchronous relaxation dynamics is employed to obtain the magnetization versus field hysteresis loops. The focus is on the analysis of the number and size distribution of the magnetization avalanches. They are classified as being nonspanning, one-dimensional-spanning, two-dimensional-spanning, or three-dimensional-spanning depending on whether or not they span the whole lattice in different space directions. Moreover, finite-size scaling analysis enables identification of two different types of nonspanning avalanches (critical and noncritical) and two different types of three-dimensional-spanning avalanches (critical and subcritical), whose numbers increase with L as a power law with different exponents. We conclude by giving a scenario for avalanche behavior in the thermodynamic limit.

Clinal variation in a brown lemur (Eulemur spp.) hybrid zone: Combining morphological, genetic and climatic data to examine stability.

Studies of hybrid zones can inform our understanding of reproductive isolation and speciation. Two species of brown lemur (Eulemur rufifrons and E. cinereiceps) form an apparently stable hybrid zone in the Andringitra region of south-eastern Madagascar. The aim of this study was to identify factors that contribute to this stability. We sampled animals at 11 sites along a 90-km transect through the hybrid zone and examined variation in 26 microsatellites, the D-loop region of mitochondrial DNA, six pelage and nine morphological traits; we also included samples collected in more distant allopatric sites. Clines in these traits were noncoincident, and there was no increase in either inbreeding coefficients or linkage disequilibrium at the centre of the zone. These results could suggest that the hybrid zone is maintained by weak selection against hybrids, conforming to either the tension zone or geographical selection-gradient model. However, a closer examination of clines in pelage and microsatellites indicates that these clines are not sigmoid or stepped in shape but instead plateau at their centre. Sites within the hybrid zone also occur in a distinct habitat, characterized by greater seasonality in precipitation and lower seasonality in temperature. Together, these findings suggest that the hybrid zone may follow the bounded superiority model, with exogenous selection favouring hybrids within the transitional zone. These findings are noteworthy, as examples supporting the bounded superiority model are rare and may indicate a process of ecologically driven speciation without geographical isolation.

The role of unions in an endogenous growth model with human capital

In this paper we study the relationship between unions and growth in a two-sector overlapping generations model with altruism and humancapital. This relationship depends on the interaction between the technology in the sector that produces human capital, the degreeof unionization of the economy and the operativeness of the bequest motive.

Mass movement characterization using a reflexion and refraction seismic survey with the sloping local base level concept

This study proposes a new concept for upscaling local information on failure surfaces derived from geophysical data, in order to develop the spatial information and quickly estimate the magnitude and intensity of a landslide. A new vision of seismic interpretation on landslides is also demonstrated by taking into account basic geomorphic information with a numeric method based on the Sloping Local Base Level (SLBL). The SLBL is a generalization of the base level defined in geomorphology applied to landslides, and allows the calculation of the potential geometry of the landslide failure surface. This approach was applied to a large scale landslide formed mainly in gypsum and situated in a former glacial valley along the Rhone within the Western European Alps. Previous studies identified the existence of two sliding surfaces that may continue below the level of the valley. In this study. seismic refraction-reflexion surveys were carried out to verify the existence of these failure surfaces. The analysis of the seismic data provides a four-layer model where three velocity layers (<1000 ms(-1), 1500 ms(-1) and 3000 ms(-1)) are interpreted as the mobilized mass at different weathering levels and compaction. The highest velocity layer (>4000 ms(-1)) with a maximum depth of similar to 58 m is interpreted as the stable anhydrite bedrock. Two failure surfaces were interpreted from the seismic surveys: an upper failure and a much deeper one (respectively 25 and 50 m deep). The upper failure surface depth deduced from geophysics is slightly different from the results obtained using the SLBL, and the deeper failure surface depth calculated with the SLBL method is underestimated in comparison with the geophysical interpretations. Optimal results were therefore obtained by including the seismic data in the SLBL calculations according to the geomorphic limits of the landslide (maximal volume of mobilized mass = 7.5 x 10(6) m(3)).

Intrahepatic mRNA levels of SOCS1 and SOCS3 are associated with cirrhosis but do not predict virological response to therapy in chronic hepatitis C.

BACKGROUND: Antiviral treatment of chronic hepatitis C is not invariably successful, costly and associated with serious side-effects, and therefore should be indicated only when the chances of benefitting patients exceed the potential risks. The suppressor of cytokine signalling (SOCS) family members have been suggested to affect the rate of virological response to therapy, but the published evidence is conflicting. METHODS: We measured the intrahepatic SOCS1, SOCS3 and SOCS7 mRNA levels in 107 chronic hepatitis C patients and assessed their clinical and histological correlates with the virological response to therapy and with some factors known for affecting treatment outcome. RESULTS: By multivariate analysis, SOCS1, SOCS3 and SOCS7 mRNA levels were not associated with rapid or sustained virological response. Similarly, no association was found between the levels of any intrahepatic SOCS mRNA and those of the homeostasis model assessment of insulin resistance. Conversely, SOCS1 (OR 2.185, 95% CI 1.223-3.906, P=0.0083) and SOCS3 (OR 40.601, 95% CI 2.357-699.25, P=0.0108) mRNA level (but not SOCS7), together with age (OR 1.156, 95% CI 1.049-1.275, P=0.0036), were independently associated with cirrhosis. CONCLUSIONS: Intrahepatic SOCS1, SOCS3 and SOCS7 mRNA levels do not predict virological response to therapy in chronic hepatitis C. The association between SOCS1, SOCS3 and cirrhosis warrants further study.

Knowledge management: uncovering risky gaps underlying the criticisms and moving to another perspective

The comments related to the sustainability of knowledge management (KM) have shown signs that it possibly can be a discourse which determines a quick style, but otherwise have also allowed the building of a better understanding about the limits and weaknesses of the knowlege management. In addition to the criticisms, the conceptual bases of knowledge management have been undermined by a contradictory combination of paradigms; there are also contradictions between the theoretical perspective jubjacent to the knwoledge management and its operationality. As a way of minimizing the possibility that the knowledge management may be turned into an umbrella concept and fail, it is suggested that its approaches embody a more interpretative perspective, taking up the role of an instrument which enables and facilitates the processes and practices in building up knowledge and information, enhancing their focus on the support to the establishment of human competences in order to deal intelligently with the present overcharge of information resources and need for building up information in the organizations.

Immune and stress responses covary with melanin-based coloration in the barn swallow

Eumelanin and pheomelanin are the main endogenous pigments in animals and melanin-based coloration has multiple functions. Melanization is associated with major life-history traits, including immune and stress response, possibly because of pleiotropic effects of genes that control melanogenesis. The net effects on pheo- versus eumelanization and other life-history traits may depend on the antagonistic effects of the genes that trigger the biosynthesis of either melanin form. Covariation between melanin-based pigmentation and fitness traits enforced by pleiotropic genes has major evolutionary implications particularly for socio-sexual communication. However, evidence from non-model organisms in the wild is limited to very few species. Here, we tested the hypothesis that melanin-based coloration of barn swallow (Hirundo rustica) throat and belly feathers covaries with acquired immunity and activation of the hypothalamic-pituitary-adrenal (HPA) axis, as gauged by corticosterone plasma levels. Individuals of both sexes with darker brownish belly feathers had weaker humoral immune response, while darker males had higher circulating corticosterone levels only when parental workload was experimentally reduced. Because color of belly feathers depends on both eu- and pheomelanin, and its darkness decreases with an increase in the concentration of eu- relative to pheomelanin, these results are consistent with our expectation that relatively more eu- than pheomelanized individuals have better immune response and smaller activation of the HPA-axis. Covariation of immune and stress response arose for belly but not throat feather color, suggesting that any function of color as a signal of individual quality or of alternative life-history strategies depends on plumage region.

Association of major and minor ECG abnormalities with coronary heart disease events.

CONTEXT: In populations of older adults, prediction of coronary heart disease (CHD) events through traditional risk factors is less accurate than in middle-aged adults. Electrocardiographic (ECG) abnormalities are common in older adults and might be of value for CHD prediction. OBJECTIVE: To determine whether baseline ECG abnormalities or development of new and persistent ECG abnormalities are associated with increased CHD events. DESIGN, SETTING, AND PARTICIPANTS: A population-based study of 2192 white and black older adults aged 70 to 79 years from the Health, Aging, and Body Composition Study (Health ABC Study) without known cardiovascular disease. Adjudicated CHD events were collected over 8 years between 1997-1998 and 2006-2007. Baseline and 4-year ECG abnormalities were classified according to the Minnesota Code as major and minor. Using Cox proportional hazards regression models, the addition of ECG abnormalities to traditional risk factors were examined to predict CHD events. MAIN OUTCOME MEASURE: Adjudicated CHD events (acute myocardial infarction [MI], CHD death, and hospitalization for angina or coronary revascularization). RESULTS: At baseline, 276 participants (13%) had minor and 506 (23%) had major ECG abnormalities. During follow-up, 351 participants had CHD events (96 CHD deaths, 101 acute MIs, and 154 hospitalizations for angina or coronary revascularizations). Both baseline minor and major ECG abnormalities were associated with an increased risk of CHD after adjustment for traditional risk factors (17.2 per 1000 person-years among those with no abnormalities; 29.3 per 1000 person-years; hazard ratio [HR], 1.35; 95% CI, 1.02-1.81; for minor abnormalities; and 31.6 per 1000 person-years; HR, 1.51; 95% CI, 1.20-1.90; for major abnormalities). When ECG abnormalities were added to a model containing traditional risk factors alone, 13.6% of intermediate-risk participants with both major and minor ECG abnormalities were correctly reclassified (overall net reclassification improvement [NRI], 7.4%; 95% CI, 3.1%-19.0%; integrated discrimination improvement, 0.99%; 95% CI, 0.32%-2.15%). After 4 years, 208 participants had new and 416 had persistent abnormalities. Both new and persistent ECG abnormalities were associated with an increased risk of subsequent CHD events (HR, 2.01; 95% CI, 1.33-3.02; and HR, 1.66; 95% CI, 1.18-2.34; respectively). When added to the Framingham Risk Score, the NRI was not significant (5.7%; 95% CI, -0.4% to 11.8%). CONCLUSIONS: Major and minor ECG abnormalities among older adults were associated with an increased risk of CHD events. Depending on the model, adding ECG abnormalities was associated with improved risk prediction beyond traditional risk factors.

Independent Central Banks: Low inflation at no cost?: A model with fiscal policy

In this article we extend the rational partisan model of Alesina and Gatti (1995) to include a second policy, fiscal policy, besides monetary policy. It is shown that, with this extension, the politically induced variance of output is not always eliminated nor reduced by delegating monetary policy to an independent and conservative central bank. Further, in flation and output stabilisation will be affected by the degree of conservativeness of the central bank and by the probability of the less in flation averse party gaining power. Keywords: rational partisan theory; fiscal policy; independent central bank JEL Classi fication: E58, E63.