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We consider a class of nonequilibrium systems of interacting agents with pairwise interactions and quenched disorder in the dynamics featuring, in the thermodynamic limit, phase transitions. We identify mathematical conditions on the microscopic interaction structure, namely the separability of the interaction kernel, that lead to a dimension reduction of the system in terms of a finite number of reaction coordinates (RCs). Such RCs prove to be proper nonequilibrium thermodynamic variables as they carry information on correlation, memory and resilience properties of the system. Phase transitions can be identified and quantitatively characterised as singularities of the complex valued susceptibility functions associated to the RCs. We provide analytical and numerical evidence of how the singularities affect the physical properties of finite size systems. [ABSTRACT FROM AUTHOR]

We study a two-layer energy balance model that allows for vertical exchanges between a surface layer and the atmosphere. The evolution equations of the surface temperature and the atmospheric temperature are coupled by the emission of infrared radiation by one level, that emission being partly captured by the other layer, and the effect of all non-radiative vertical exchanges of energy. Therefore, an essential parameter is the absorptivity of the atmosphere, denoted ε a. The value of ε a depends critically on greenhouse gases: increasing concentrations of CO 2 and CH 4 lead to a more opaque atmosphere with higher values of ϵ a. First, we prove that global existence of solutions of the system holds if and only if ε a ∈ (0 , 2) and blow up in finite time occurs if ε a > 2. (Note that the physical range of values for ε a is (0 , 1 ].) Next, we explain the long time dynamics for ε a ∈ (0 , 2) , and we prove that all solutions converge to some equilibrium point. Finally, motivated by the physical context, we study the dependence of the equilibrium points with respect to the involved parameters, and we prove, in particular, that the surface temperature increases monotonically with respect to ε a. This is the key mathematical manifestation of the greenhouse effect. [ABSTRACT FROM AUTHOR]

A general circulation model of intermediate complexity with an idealized earthlike aquaplanet setup is used to study the impact of changes in the oceanic heat transport on the global atmospheric circulation. Focus is put on the Lorenz energy cycle and the atmospheric mean meridional circulation. The latter is analysed by means of the Kuo-Eliassen equation. The atmospheric heat transport compensates the imposed oceanic heat transport changes to a large extent in conjunction with significant modification of the general circulation. Up to a maximum about 3PW, an increase of the oceanic heat transport leads to an increase of the global mean near-surface temperature and a decrease of its equator-to-pole gradient. For larger transports, the gradient is reduced further but the global mean remains approximately constant. This is linked to a cooling and a reversal of the temperature gradient in the tropics. A larger oceanic heat transport leads to a reduction of all reservoirs and conversions of the Lorenz energy cycle but of different relative magnitude for the individual components. The available potential energy of the zonal mean flow and its conversion to eddy available potential energy are affected most. Both the Hadley and Ferrel cell show a decline for increasing oceanic heat transport, with the Hadley cell being more sensitive. Both cells exhibit a poleward shift of their maxima, and the Hadley cell broadens for larger oceanic transports. The partitioning, by means of the Kuo-Eliassen equation, reveals that zonal mean diabatic heating and friction are the most important sources for changes of the Hadley cell, while the behaviour of the Ferrell cell is mostly controlled by friction. [ABSTRACT FROM AUTHOR]

Introduction: Patients with schizophrenia show severe difficulties in interpersonal communication, including impairments in conversation skills, like the turn-taking. To our knowledge, very few studies to date have taken into account conversation analysis in order to investigate turn-taking in schizophrenia patients. Objectives: To investigate the conversational patterns in schizophrenia patients; to assess possible associations between dialogic features, abnormal subjective experiences and symptom dimensions. Methods: Thirty-six patients with Schizophrenia underwent an interview, subsequently analyzed with an innovative semi-automatic analysis. Positive and Negative Syndrome Scale (PANSS) was adopted for the investigation of psychopathology and Examination of Anomalous Self Experience (EASE) for Self-Disorders. Results: Dialogic exchanges are graphically represented in Figure 1. An inverse correlation was found between participant speaking time and PANSS negative symptoms score (r = -0.44, p value < 0.05; Figure 2), whereas no associations were found between conversational variables and PANSS positive or disorganization dimensions. Finally, a positive correlation was found between the EASE item "spazialization of thought" and average pause duration (r = 0.42, p value < 0.05). Conclusions: The finding of a relationship between negative symptoms and conversational patterns suggest that conversational features in schizophrenia are expression of the "core" negative dimension of the disorder. The association with the phenomenon of thought spatialization seems to suggest that the disturbances of the stream of consciousness impact on natural dialogic interactions. Ultimately, conversation analysis seems a promising tool to study dialogic exchanges of patients with schizophrenia. [ABSTRACT FROM AUTHOR]

In this study, we investigate how PCMDI/CMIP3 general circulation models (GCMs) represent the seasonal properties of the hydrological cycle in four major South and Southeast Asian river basins (Indus, Ganges, and Brahmaputra and Mekong). First, we examine the skill of GCMs by analysing their simulations for the XX century climate (1961-2000) under present-day forcing, and then we analyse the projected changes for the corresponding XXI and XXII century climates under SRESA1B scenario. CMIP3 GCMs show a varying degree of skill in simulating the basic characteristics of the monsoonal precipitation regimes of the Ganges, Brahmaputra and Mekong basins, while the representation of the hydrological cycle over the Indus basin is poor in most cases, with few GCMs not capturing the monsoon signal at all. Although the models' outputs feature a remarkable spread for the monsoonal precipitations, a satisfactory representation of the western mid-latitude precipitation regime is instead observed. Similarly, most of the models exhibit a satisfactory agreement for the basin-integrated runoff in winter and spring, while the spread is large for the runoff during the monsoon season. For future climate scenarios, winter (spring) P - E decreases over all four (Indus and Ganges) basins due to decrease in precipitation associated with the western midlatitude disturbances. Consequently, the spring (winter) runoff drops (rises) for the Indus and Ganges basins. Such changes indicate a shift from rather glacial and nival to more pluvial runoff regimes, particularly for the Indus basin. Furthermore, the rise in the projected runoff along with the increase in precipitations during summer and autumn indicates an intensification of the summer monsoon regime for all study basins. [ABSTRACT FROM AUTHOR]

We investigate how the climate models contributing to the PCMDI/CMIP3 dataset describe the hydrological cycle over four major South and Southeast Asian river basins (Indus, Ganges, Brahmaputra and Mekong) for the 20th, 21st (13 models) and 22nd (10 models) centuries. For the 20th century, some models do not seem to conserve water at the river basin scale up to a good degree of approximation. The simulated precipitation minus evaporation (P -E), total runoff (R) and precipitation (P) quantities are neither consistent with the observations nor among the models themselves. Most of the models underestimate P - E for all four river basins, which is mainly associated with the underestimation of precipitation. This is in agreement with the recent results on the biases of the representation of monsoonal dynamics by GCMs. Overall, a modest inter-model agreement is found only for the evaporation and inter-annual variability of P - E. For the 21st and 22nd centuries, models agree on the negative (positive) changes of P - E for the Indus basin (Ganges, Brahmaputra and Mekong basins). Most of the models foresee an increase in the inter-annual variability of P - E for the Ganges and Mekong basins, thus suggesting an increase in large low-frequency dry/wet events. Instead, no considerable future change in the inter-annual variability of P - E is found for the Indus and Brahmaputra basins. [ABSTRACT FROM AUTHOR]

In this paper we explore the potential multistability of the climate for a planet around the habitable zone. We focus on conditions reminiscent to those of the Earth system, but our investigation has more general relevance and aims at presenting a general methodology for dealing with exoplanets. We describe a formalism able to provide a thorough analysis of the non-equilibrium thermodynamical properties of the climate system and explore, using a flexible climate model, how such properties depend on the energy input of the parent star, on the infrared atmospheric opacity, and on the rotation rate of the planet. We first show that it is possible to reproduce the multi-stability properties reminiscent of the paleoclimatologically relevant snowball (SB)-warm (W) conditions. We then characterise the thermodynamics of the simulated Wand SB states, clarifying the central role of the hydrological cycle in shaping the irreversibility and the efficiency of the W states, and emphasizing the extreme diversity of the SB states, where dry conditions are realized. Thermodynamics provides the clue for studying the tipping points of the system and leads us to constructing empirical parametrizations allowing for expressing the main thermodynamic properties as functions of the emission temperature of the planet only. Such empirical functions are shown to be rather robust with respect to changing the rotation rate of the planet from the current terrestrial one to half of it. Furthermore, we explore the dynamical range where the length of the day and the length of the year are comparable. We clearly find that there is a critical rotation rate below which the multi-stability properties are lost, and the ice-albedo feedback responsible for the presence of SB and W conditions is damped. The bifurcation graph of the system suggests the presence of a phase transition in the planetary system. Such critical rotation rate corresponds roughly to the phase-lock 2:1 condition. Therefore, if an Earth-like planet is 1:1 phase-locked with respect to the parent star, only one climatic state would be compatible with a given set of astronomical and astro-physical parameters. These results have relevance for the general theory of planetary circulation and for the definition of necessary and sufficient conditions for habitability. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Abstract: We consider the Nambu and Hamiltonian representations of Rayleigh–Bénard convection with a nonlinear thermal heating effect proportional to the Eckert number (). The model that we use is an extension of the classical Lorenz-63 model with four kinematic and six thermal degrees of freedom. The conservative parts of the dynamical equations which include all nonlinearities satisfy Liouville’s theorem and permit a conserved Hamiltonian for arbitrary . For two independent conserved functions exist; one of these is associated with unavailable potential energy and is also present in the Lorenz-63 truncation. This function which is a Casimir of the noncanonical Hamiltonian system is used to construct a Nambu representation of the conserved part of the dynamics. The thermal heating effect can be represented either by a second canonical Hamiltonian or as a gradient (metric) system using the time derivative of the Casimir. The results demonstrate the impact of viscous heating in the total energy budget and in the Lorenz energy cycle for kinetic and available potential energy. [Copyright &y& Elsevier]

Many natural systems show emergent phenomena at different scales, leading to scaling regimes with signatures of deterministic chaos at large scales and an apparently random behavior at small scales. These features are usually investigated quantitatively by studying the properties of the underlying attractor, the compact object asymptotically hosting the trajectories of the system with their invariant density in the phase space. This multi-scale nature of natural systems makes it practically impossible to get a clear picture of the attracting set. Indeed, it spans over a wide range of spatial scales and may even change in time due to non-stationary forcing. Here, we combine an adaptive decomposition method with extreme value theory to study the properties of the instantaneous scale-dependent dimension, which has been recently introduced to characterize such temporal and spatial scale-dependent attractors in turbulence and astrophysics. To provide a quantitative analysis of the properties of this metric, we test it on the well-known low-dimensional deterministic Lorenz-63 system perturbed with additive or multiplicative noise. We demonstrate that the properties of the invariant set depend on the scale we are focusing on and that the scale-dependent dimensions can discriminate between additive and multiplicative noise despite the fact that the two cases have exactly the same stationary invariant measure at large scales. The proposed formalism can be generally helpful to investigate the role of multi-scale fluctuations within complex systems, allowing us to deal with the problem of characterizing the role of stochastic fluctuations across a wide range of physical systems. [ABSTRACT FROM AUTHOR]

Negative refractive index media have become a hot topic in physics due to their proposed revolutionary properties, which would have drastic consequences in design of novel optical devices. We show that Kramers-Kronig relations connecting the real and imaginary parts of the complex refractive index of absorbing media are valid even though the real refractive index may take negative value at some spectral range. In addition universal sum rules for linear optical constants of negative index media are also valid. This means that negative refractive index media are not fundamentally different from regular media. Hence, any spectrum measured from negative refractive index media can be analyzed using dispersion relations and sum rules, which have so far provided information on the optical properties of materials. [ABSTRACT FROM AUTHOR]

The article presents case study of a 54-year-old woman, with a history of breast cancer with bone metastases, who was treated with an oral I PI3K inhibitor. The patient became irritable and verbally aggressive, and later she was hyperactive, and easily distractive. On evaluations she was found to be extremely talkative, with flight of ideas, grandiosity, and high irritability, and was put on Olanzapine and Lorazepam. Onset of a manic episode during treatment was confirmed.

A general circulation model of intermediate complexity with an idealized Earth-like aquaplanet setup is used to study the impact of changes in the oceanic heat transport on the global atmospheric circulation. Focus is on the atmospheric mean meridional circulation and global thermodynamic properties. The atmosphere counterbalances to a large extent the imposed changes in the oceanic heat transport, but, nonetheless, significant modifications to the atmospheric general circulation are found. Increasing the strength of the oceanic heat transport up to 2.5PW leads to an increase in the global mean near-surface temperature and to a decrease in its equator-to-pole gradient. For stronger transports, the gradient is reduced further, but the global mean remains approximately constant. This is linked to a cooling and a reversal of the temperature gradient in the tropics. Additionally, a stronger oceanic heat transport leads to a decline in the intensity and a poleward shift of the maxima of both the Hadley and Ferrel cells. Changes in zonal mean diabatic heating and friction impact the properties of the Hadley cell, while the behavior of the Ferrel cell is mostly controlled by friction. The efficiency of the climate machine, the intensity of the Lorenz energy cycle and the material entropy production of the system decline with increased oceanic heat transport. This suggests that the climate system becomes less efficient and turns into a state of reduced entropy production as the enhanced oceanic transport performs a stronger large-scale mixing between geophysical fluids with different temperatures, thus reducing the available energy in the climate system and bringing it closer to a state of thermal equilibrium. [ABSTRACT FROM AUTHOR]

For the discrete model suggested by Lorenz in 1996, a one-dimensional long-wave approximation with nonlinear excitation and diffusion is derived. The model is energy conserving but non-Hamiltonian. In a low-order truncation, weak external forcing of the zonal mean flow induces avalanchelike breather solutions which cause reversal of the mean flow by a wave-mean flow interaction. The mechanism is an outburst-recharge process similar to avalanches in a sandpile model. [ABSTRACT FROM AUTHOR]

The atmospheric meridional energy transport in the Northern Hemisphere midlatitudes is mainly accomplished by planetary and synoptic waves. A decomposition into wave components highlights the strong seasonal dependence of the transport, with both the total transport and the contributions from planetary and synoptic waves peaking in winter. In both winter and summer months, poleward transport extremes primarily result from a constructive interference between planetary and synoptic motions. The contribution of the mean meridional circulation is close to climatology. Equatorward transport extremes feature a mean meridional equatorward transport in winter, while the planetary and synoptic modes mostly transport energy poleward. In summer, a systematic destructive interference occurs, with planetary modes mostly transporting energy equatorward and synoptic modes again poleward. This underscores that baroclinic conversion dominates regardless of season in the synoptic wave modes, whereas the planetary waves can be either free or forced, depending on the season. Plain Language Summary: The atmospheric heat transport from low to high latitudes is the main mechanism through which the climate reequilibrates the latitudinally uneven absorption of solar radiation. The atmospheric transport is fueled by instabilities driven by the presence of temperature differences between low and high latitudes and acts in such a way to reduce such gradient. This is one of the main stabilizing mechanisms of the climate system. In this work, we investigate how motions of different spatial scales contribute to atmospheric heat transports in the Northern Hemisphere. We discover that the relative importance of synoptic and planetary scale atmospheric motions is different in summer and winter. Our analysis delves into the analysis of events associated with extreme heat transport toward high latitudes, where we see a compensating mechanism between synoptic and planetary atmospheric motions. We further study days characterized by very large and very small (or even negative) heat transport toward the high latitudes. These "extreme events" are driven by complex interactions between the different scales. Our results are relevant for elucidating basic dynamical and thermodynamical properties of the atmosphere and can be used to benchmark the performance of climate models. Key Points: Competition exists in all seasons between regular and extreme meridional transports performed by zonal mean, synoptic and planetary wavesWinter and summer poleward heat transport extremes are driven by the combined effect of planetary and synoptic wavesEquatorward transport extremes are driven by synoptic and planetary waves interaction in summer, predominantly by planetary waves in winter [ABSTRACT FROM AUTHOR]

Schizophrenia has been described as a psychiatric condition characterized by deficits in one's own and others' face recognition, as well as by a disturbed sense of body-ownership. To date, no study has integrated these two lines of research with the aim of investigating Enfacement Illusion (EI) proneness in schizophrenia. To accomplish this goal, the classic EI protocol was adapted to test the potential plasticity of both Self-Other and Other-Other boundaries. Results showed that EI induced the expected malleability of Self-Other boundary among both controls and patients. Interestingly, for the first time, the present study demonstrates that also the Other-Other boundary was influenced by EI. Furthermore, comparing the two groups, the malleability of the Other-Other boundary showed an opposite modulation. These results suggest that, instead of greater Self-Other boundary plasticity, a qualitative difference can be detected between schizophrenia patients and controls in the malleability of the Other-Other boundary. The present study points out a totally new aspect about body-illusions and schizophrenia disorder, demonstrating that EI is not only confined to self-sphere but it also affects the way we discriminate others, representing a potential crucial aspect in the social domain. [ABSTRACT FROM AUTHOR]

Background Bipolar Disorder is characterised by opposite fluctuations of mood and goal-directed behaviours (i.e. manic and depressive episodes) interspersed with period of stability (i.e. euthymia). Deficit in executive control have been observed both in the prodromal phases of the disorder and in euthymia, suggesting a trait feature. Recent models of Bipolar Disorder postulate that an imbalance between an increased bottom-up reward sensitivity and a reduced top-down prefrontal control [1] might be responsible of the phenomenology of the disorder. Aims First, evaluate whether a sample of subjects with Bipolar Disorder, compared with healthy controls, show an impairment in the attentional networks and an increased behavioural activation. Secondly explore possible interactions of these characteristics with symptoms domains. Methods Thirty-five subjects with Bipolar Disorder and 35 matched healthy controls completed an attentional task (Attentional Network Task Revised, ANT-R) [2]. Participants were assessed on temperament (ATQ), behavioural activation/inhibition (BIS-BAS), disorder of thinking (STOQ) and manic/depressive symptoms (HDRS and YMRS). Groups were compared in the task outputs on the three attentional networks (alerting, orienting and executive attention). Differences were first controlled for confounding variables (e.g. age) and then added in a GLM aimed at evaluate the best predictor of the measured clinical dimensions. Significant interactions were further explored through mediation and moderation analyses. Results Compared to healthy controls, subjects with Bipolar Disorder scored significantly higher (i.e. worse performance) only in the reaction time at the Flanker effect (t=-3.560; p<0.001), the more accurate measure of executive control. In the patient group, this parameter correlated significantly with the reward responsiveness subscale of the behavioural activation scale (r= 436; p<0.001) even when controlling for possible confounders (p=0.01). Interestingly we found an interaction (p=.07) between the reaction time at the Flanker effect and the behavioural activation in predicting the disorders of thoughts at STOQ, so that the relationship between the Flanker Effect and the thought over-activation disappear only at high (p=.94), but not at low (p=0.01) and average (p=0.03), levels of behavioural activation. Discussion Our results, even though limited by the small sample size, suggest that subjects with Bipolar Disorder show an impairment in attention and specifically in the executive control. This prefrontal impairment might be responsible for the thoughts over-activation observed in euthymic subjects, as a dimension that goes from depressive rumination to acceleration of ideas. This relationship, however, depends on the subject levels of behavioural activation; in fact at high level of reward responsiveness, the prefrontal control might lose its top-down effect on symptoms phenomenology. Conclusions Treatments aimed at targeting both reward and attention circuits [3] might improve the course of the disorder. Further studies, including a computational approach to information integration in attentional tasks [4] should confirm our preliminary results and test the hypothesis of a learning impairment in the genesis and maintenance of Bipolar Disorder [5]. [ABSTRACT FROM AUTHOR]

Introduction Recent studies have underlined the importance of considering the form of thoughts, beyond their content, in order to achieve a better phenomenological comprehension of mental states in mood disorders. The subjective experience of thought overactivation is an important feature of mood disorders that could help in identifying, among patients with a depressive episode, those who belong to the bipolar spectrum. Objectives Patients with a diagnosis of bipolar disorder (BD) were compared with matched healthy controls (HC) on a scale that evaluates thought overactivation. Aims Validate the Italian version of a scale for thought overactivation (i.e. STOQ) in a sample of bipolar patients. Methods Thirty euthymic BD and 30 HC completed the Subjective Thought Overactivation Questionnaire (STOQ), the Ruminative Responses Scale (RRS), the Beck Depression Inventory-II (BDI-II) and global functioning (VGF). Results The 9-items version of the STOQ has been back translated and its internal consistency in this sample was satisfactory (alpha = .91). Both the brooding subscore of RRS (b-RRS) ( r = .706; P < .001) and STOQ ( r = .664; P < .001) correlate significantly with depressive symptoms whereas only the first correlate with VGF ( r = –.801; P < .001). The two groups did not differed in the b-RRS (HC = 8.41 vs BD = 9.72; P = .21), whereas BD where significantly higher in the STOQ total score (HC = 6.62 vs. BD = 14.9; P = .007). Conclusion Our results, although limited by the small sample size, confirm the validity of the STOQ and suggest that this scale could grasp a feature characteristic of BD, independently from their tendency to ruminate. The latter seems to impact more on global functioning. [ABSTRACT FROM AUTHOR]

Abstract: Global and zonal monthly means of cloud cover fraction for total cloudiness (CF) from the ISCCP D2 dataset are compared to same quantities produced by the 20th century simulations of 21 climate models from the World Climate Research Programme''s (WCRP''s) Coupled Model Intercomparison Project phase 3 (CMIP3). The comparison spans the time frame from January 1984 to December 1999 and the global and zonal averages of CF are studied. It is shown that the global mean of CF for the PCMDI-CMIP3 models, averaged over the whole period, exhibits a considerable variance and generally underestimates the ISCCP value. Large differences among models, and between models and observations, are found in the polar areas, where both models and satellite observations are less reliable, and especially near Antarctica. For this reason the zonal analysis is focused over the 60° S–60° N latitudinal belt, which includes the tropical area and mid-latitudes. The two hemispheres are analysed separately to show the variation of the amplitude of the seasonal cycle. Most models underestimate the yearly averaged values of CF over all the analysed areas, whilst they capture, in a qualitatively correct way, the magnitude and the sign of the seasonal cycle over the whole geographical domain, but overestimate the amplitude of the seasonal cycle in the tropical areas and at mid-latitudes, when taken separately. The interannual variability of the yearly averages is underestimated by all models in each area analysed, and also the interannual variability of the amplitude of the seasonal cycle is underestimated, but to a lesser extent. This work shows that the climate models have a heterogeneous behaviour in simulating the CF over different areas of the Globe, with a very wide span both with observed CF and among themselves. Some models agree quite well with the observations in one or more of the metrics employed in this analysis, but not a single model has a statistically significant agreement with the observational datasets on yearly averaged values of CF and on the amplitude of the seasonal cycle over all analysed areas. [Copyright &y& Elsevier]

The article presents a study which focuses on the reconsideration of the Maximum Entropy Production conjecture (MEP) for the representation of the total material entropy production due at the same time to both horizontal and vertical heat fluxes. It says that a fixed longwave transmissivity was assumed to obtained the MEP solutions. It adds that MEP can predict the thermal meridional structure of the atmosphere once the isolation is given.

The article discusses a study on a Maximum Entropy Production (MEP) solution for climate model. It mentions the application of its hypothesis to a four-box model of climate which answers for horizontal and vertical material heat fluxes. It also notes that the solution is found with realistic temperature and fluxes along with the involvement of meridional and vertical entropy production terms in the maximization making it applicable to each subsystem.

A statistical methodology is proposed and tested for the analysis of extreme values of atmospheric wave activity at mid-latitudes. The adopted methods are the classical block-maximum and peak over threshold, respectively based on the generalized extreme value (GEV) distribution and the generalized Pareto distribution (GPD). Time-series of the ‘Wave Activity Index’ (WAI) and the ‘Baroclinic Activity Index’ (BAI) are computed from simulations of the General Circulation Model ECHAM4.6, which is run under perpetual January conditions. Both the GEV and the GPD analyses indicate that the extremes of WAI and BAI are Weibull distributed, this corresponds to distributions with an upper bound. However, a remarkably large variability is found in the tails of such distributions; distinct simulations carried out under the same experimental setup provide sensibly different estimates of the 200-yr WAI return level. The consequences of this phenomenon in applications of the methodology to climate change studies are discussed. The atmospheric configurations characteristic of the maxima and minima of WAI and BAI are also examined. [ABSTRACT FROM AUTHOR]