Message passing and Monte Carlo algorithms: connecting fixed points with metastable states

Mean field-like approximations (including naive mean field, Bethe and Kikuchi and more general Cluster Variational Methods) are known to stabilize ordered phases at temperatures higher than the thermodynamical transition. For example, in the Edwards-Anderson model in 2-dimensions these approximations predict a spin glass transition at finite $T$. Here we show that the spin glass solutions of the Cluster Variational Method (CVM) at plaquette level do describe well actual metastable states of the system. Moreover, we prove that these states can be used to predict non trivial statistical quantities, like the distribution of the overlap between two replicas. Our results support the idea that message passing algorithms can be helpful to accelerate Monte Carlo simulations in finite dimensional systems.Comment: 6 pages, 6 figure

Langevin dynamics of fluctuation induced first order phase transitions: self consistent Hartree Approximation

The Langevin dynamics of a system exhibiting a Fluctuation Induced First Order Phase Transition is solved within the self consistent Hartree Approximation. Competition between interactions at short and long length scales gives rise to spatial modulations in the order parameter, like stripes in 2d and lamellae in 3d. We show that when the time scale of observation is small compared with the time needed to the formation of modulated structures, the dynamics is dominated by a standard ferromagnetic contribution plus a correction term. However, once these structures are formed, the long time dynamics is no longer pure ferromagnetic. After a quench from a disordered state to low temperatures the system develops growing domains of stripes (lamellae). Due to the character of the transition, the paramagnetic phase is metastable at all finite temperatures, and the correlation length diverges only at T=0. Consequently, the temperature is a relevant variable, for $T>0$ the system exhibits interrupted aging while for T=0 the system ages for all time scales. Furthermore, for all $T$, the exponent associated with the aging phenomena is independent of the dimension of the system.Comment: 16 pages, 1 figur

Development and Assessment of a Groundwater Sustainability Index in Climatically Diverse Groundwater Irrigated Regions in Nebraska

The aim of this research was to evaluate the impact of regional change in ET on groundwater level changes and the assessment and development of a groundwater sustainability index for climatically diverse regions across Nebraska during 2000-2014. Irrigation in the selected regions is predominantly supplied by groundwater. The hypothesis is that groundwater use can become sustainable if the regional evapotranspiration (ET) is managed so that it equals the ET of vegetation that is native to the region. Site locations were Box Butte, Chase, Dundy, Holt LNNRD and York Counties and 3 ecosystems were evaluated: native vegetation, dryland and irrigated cropping systems. Methodology consisted of remote sensing data analysis, GIS modeling, ASCE-Penman Monteith Evapotranspiration equation (Allen et al., 2005) and analysis of historical data. Precipitation, ET, NDVI, Kc and ET weighed to obtain county average ET .Groundwater level declines and groundwater storage data were assessed and compared with ET. Also the same procedures were applied at the township scale for 5 townships in each county. Results showed that precipitation increased from west to east ranging between 406-693 mm.y-1. York County had the overall highest ET values, and Box Butte County had the lowest. Annual native vegetation ET ranged 382-644 mm.y-1 and county annual ET ranged 415-720 mm.y-1 from west to east. The highest groundwater level declines were in Box Butte, Dundy and York Counties (0.26 m.y-1) and the lowest in Holt LNNRD (0.12 m.y-1).Sustainability index (SI) indicated that Holt LNNRD was the most sustainable in water use (SI=0.94) and Chase County the least sustainable (SI=0.88). County average ET exceeded native vegetation ET in all cases due to the higher ET of irrigated crops. The positive correlation between ET increases and reduction in water storage showed a significant correlation (0.62) at p-value \u3c 0.05 level confidence, n=10. Higher SI resulted in lower reduction in groundwater storage. The negative correlation between SI and reduction in groundwater storage (-0.69) proved to be significant at p-value\u3c 0.025, n=10. However, data suggested that reducing county average ET, approaching that of native vegetation, which kept water levels in balance in the past, could be a promising practice. Advisor: Dean E. Eisenhaue

Development and Assessment of a Groundwater Sustainability Index in Climatically Diverse Groundwater Irrigated Regions in Nebraska

The aim of this research was to evaluate the impact of regional change in ET on groundwater level changes and the assessment and development of a groundwater sustainability index for climatically diverse regions across Nebraska during 2000-2014. Irrigation in the selected regions is predominantly supplied by groundwater. The hypothesis is that groundwater use can become sustainable if the regional evapotranspiration (ET) is managed so that it equals the ET of vegetation that is native to the region. Site locations were Box Butte, Chase, Dundy, Holt LNNRD and York Counties and 3 ecosystems were evaluated: native vegetation, dryland and irrigated cropping systems. Methodology consisted of remote sensing data analysis, GIS modeling, ASCE-Penman Monteith Evapotranspiration equation (Allen et al., 2005) and analysis of historical data. Precipitation, ET, NDVI, Kc and ET weighed to obtain county average ET .Groundwater level declines and groundwater storage data were assessed and compared with ET. Also the same procedures were applied at the township scale for 5 townships in each county. Results showed that precipitation increased from west to east ranging between 406-693 mm.y-1. York County had the overall highest ET values, and Box Butte County had the lowest. Annual native vegetation ET ranged 382-644 mm.y-1 and county annual ET ranged 415-720 mm.y-1 from west to east. The highest groundwater level declines were in Box Butte, Dundy and York Counties (0.26 m.y-1) and the lowest in Holt LNNRD (0.12 m.y-1).Sustainability index (SI) indicated that Holt LNNRD was the most sustainable in water use (SI=0.94) and Chase County the least sustainable (SI=0.88). County average ET exceeded native vegetation ET in all cases due to the higher ET of irrigated crops. The positive correlation between ET increases and reduction in water storage showed a significant correlation (0.62) at p-value \u3c 0.05 level confidence, n=10. Higher SI resulted in lower reduction in groundwater storage. The negative correlation between SI and reduction in groundwater storage (-0.69) proved to be significant at p-value\u3c 0.025, n=10. However, data suggested that reducing county average ET, approaching that of native vegetation, which kept water levels in balance in the past, could be a promising practice. Advisor: Dean E. Eisenhaue

Gas Chromatography-Mass Spectrometry Study of the Essential Oils of Schinus longifolia (Lindl.) Speg., Schinus fasciculata (Griseb.) I. M. Johnst., and Schinus areira L.

The essential oil composition from the aerial parts of three Anacardiaceae growing in Bah¨ªa Blanca, Argentina was studied by gas chromatography and gas chromatography-mass spectrometry. The essential oils of S. longifolia and S. fasciculata have been studied for the first time. The major constituents were ¦Á-pinene (46.5%), ¦Â-pinene (15.1%) and ¦Á-phellandrene (10.1%) for S. longifolia and limonene (10.9%), ¦Â-phellandrene (6.16%) and ¦Á-phellandrene (5.6%) for S. fasciculata. The major components of the essential oil of S. areira were limonene (28.6%), ¦Á-phellandrene (10.1%), sabinene (9.2%) and camphene (9.2%) differing from the literature data. The essential oils from S. areira and S. longifolia exhibited a high biotoxicity in a brine shrimp assay with Artemia persimilis.Fil: Murray, Ana Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina. Universidad Nacional del Sur. Departamento de Química. Instituto de Investigaciones en Química Orgánica; ArgentinaFil: Frontera, Maria Eugenia. Universidad Nacional del Sur. Departamento de Química. Instituto de Investigaciones en Química Orgánica; ArgentinaFil: Tomas, María A.. Universidad Nacional del Sur. Departamento de Química. Instituto de Investigaciones en Química Orgánica; ArgentinaFil: Mulet, María Cristina. Universidad Nacional del Sur. Departamento de Química. Instituto de Investigaciones en Química Orgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentin

Cyber-Physical Systems for Micro-/Nano-assembly Operations: a Survey

Abstract Purpose of Review Latest requirements of the global market force manufacturing systems to a change for a new production paradigm (Industry 4.0). Cyber-Physical Systems (CPS) appear as a solution to be deployed in different manufacturing fields, especially those with high added value and technological complexity, high product variants, and short time to market. In this sense, this paper aims at reviewing the introduction level of CPS technologies in micro/nano-manufacturing and how these technologies could cope with these challenging manufacturing requirements. Recent Findings The introduction of CPS is still in its infancy on many industrial applications, but it actually demonstrates its potential to support future manufacturing paradigm. However, only few research works in micro/nano-manufacturing considered CPS frameworks, since the concept barely appeared a decade ago. Summary Some contributions have revealed the potential of CPS technologies to improve manufacturing performance which may be scaled to the micro/nano-manufacturing. IoT-based frameworks with VR/AR technologies allow distributed and collaborative systems, or agent-based architectures with advance algorithm implementations that improve the flexibility and performance of micro-/nano-assembly operations. Future research of CPS in micro-/nano-assembly operations should be followed by more studies of its technical deployment showing its implications under other perspectives, i.e. sustainable, economic, and social point of views, to take full advance of all its features

Adaptive drivers in a model of urban traffic

We introduce a simple lattice model of traffic flow in a city where drivers optimize their route-selection in time in order to avoid traffic jams, and study its phase structure as a function of the density of vehicles and of the drivers' behavioral parameters via numerical simulations and mean-field analytical arguments. We identify a phase transition between a low- and a high-density regime. In the latter, inductive drivers may surprisingly behave worse than randomly selecting drivers.Comment: 7 pages, final versio

Simulating human digestion: developing our knowledge to create healthier and more sustainable foods

The gold standard for nutrition studies is clinical trials but they are expensive and variable, and do not always provide the mechanistic information required, hence the increased use of in vitro and increasingly in silico simulations of digestion. In this review, we give examples of the main simulations being used to model upper gastrointestinal tract digestion. This review ranges from the selection of enzymes to the interpretation of results from static models to fully dynamic models. We describe the modifications made to accommodate different demographic groups (infants, the elderly, etc.). We list examples of the application of the different models as well as giving the advantages and disadvantages. A model is only useful if it predicts or aids the understanding of physiological behaviour. Thus, the final section of the review makes a comparison of results obtained from experiments undertaken using in vitro simulations with those obtained in vivo. This comparison will help the reader understand the appropriateness of each model for the type of measurement to be undertaken. In particular, human studies tend to measure bioactive concentrations in blood and not in the gastrointestinal tract whereas in vitro studies often only produce data on release of nutrients into the gut lumen. This is the difficulty of comparing bioaccessibility as generated in vitro with bioavailability as generated in vivo. It is apparent that the models being used are increasingly being validated with in vivo data and this bodes well for the future

Path-integral solution of MacArthur’s resource-competition model for large ecosystems with random species-resources couplings

We solve MacArthur’s resource-competition model with random species-resource couplings in the “thermodynamic” limit of infinitely many species and resources using dynamical path integrals à la De Domincis. We analyze how the steady state picture changes upon modifying several parameters, including the degree of heterogeneity of metabolic strategies (encoding the preferences of species) and of maximal resource levels (carrying capacities), and discuss its stability. Ultimately, the scenario obtained by other approaches is recovered by analyzing an effective one-species-one-resource ecosystem that is fully equivalent to the original multi-species one. The technique used here can be applied for the analysis of other model ecosystems related to the version of MacArthur’s model considered here