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result(s) for
"Zambaldi, C"
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A Matlab toolbox to analyze slip transfer through grain boundaries
2015
Slip transmission across grain boundaries is an essential micromechanical processes during deformation of polycrystalline materials. Slip transmission processes can be characterized based on the geometrical arrangement of active slip systems in adjacent grains and the value of the critical resolved shear stress acting on the incoming and possible outgoing slip systems. We present a Matlab toolbox which enables quantification of grain boundary slip transfer properties and comparison with experiments. Using a graphical user interface, experimental grain boundary data can be directly exported as input files for crystal plasticity finite element simulation of bicrystal experiments.
Journal Article
Characterization and modeling of heterogeneous deformation in commercial purity titanium
by
Yang, Y.
,
Crimp, M. A.
,
Bieler, T. R.
in
Chemistry/Food Science
,
Crystal dislocations
,
Earth Sciences
2011
Heterogeneous deformation, including local dislocation shear activity and lattice rotation, was analyzed in microstructure patches of polycrystalline commercial purity titanium specimens using three different experimental methods. The measurements were compared with crystal plasticity finite element simulations for the same region that incorporate a local phenomenological hardening constitutive model. The dislocation activity was measured using techniques associated with atomic force microscopy, confocal microscopy, three-dimensional x-ray diffraction, and nano-indentation. The results indicate that a major challenge for model development is to effectively predict conditions where slip transfer occurs, and where geometrically necessary dislocations accumulate.
Journal Article
Hydroacoustic evaluation of the spatial and temporal distribution of fish in the upstream proximity of a dam in a Neotropical reservoir
by
Zambaldi, Ludimilla
,
Andrade, Fernanda
,
Prado, Ivo
in
Aquatic environment
,
Biological data
,
Community composition
2019
Background. Construction of dams alters the physical, chemical, and ecological characteristics of the aquatic environment and modifies fish behaviour and the community composition. Few studies have shown the diel and seasonal fish distribution in tropical reservoirs, mainly in the proximity of the dam, where the risk of injury and death of fishes, which try to migrate downstream, is high. Thus, the data obtained in these regions can encourage actions that may attenuate the impacts on ichthyofauna. Hydroacoustic sampling is an effective tool to study fish behaviour and their spatial distribution in water bodies. In this context, the aim of this study was to evaluate the spatial and seasonal distribution of fish in the reservoir of Tres Marias (Minas Gerais, Brazil), immediately upstream of the dam, using hydroacoustic and gillnet sampling. Material and methods. Hydroacoustics and gillnet sampling were carried out both during the day and at night, and during the rainy and dry seasons. For the acquisition of hydroacoustic data, we employed an echosounder (BioSonics DT-X Digital Scientific) with a split-beam digital transducer. For the biological data, gillnets of different mesh sizes were set. Results. Hydroacoustic data showed significant differences in fish depth between day and night surveys, with fish remaining in deeper water during the day, a phenomenon known as Diel Vertical Migration. Furthermore, hydroacoustic data showed that smaller fish (estimated by \"target strength\") concentrate at smaller depths. There was no significant difference in the size of fish between seasons. Limnological and operation variables were not related to the fish abundance. Distribution maps showed that during the day fishes were distributed in areas more distant from the dam, while at night they were closer to the dam. Gillnets sampled 127 individuals of 22 species and 57.5% of the collected specimens were migratory species. Conclusion. These results can contribute to the understanding of fish behaviour in reservoirs, as well as provide an empirical basis for the development of novel fish management measures for Neotropical dams.
Journal Article
Modes of death and prognostic outliers in chronic heart failure
by
Porcu, Maurizio
,
Canepa, Marco
,
Maggioni, Aldo Pietro
in
Blood pressure
,
Cholesterol
,
Chronic obstructive pulmonary disease
2019
The impact of incident sudden cardiac death (SCD) on the predictive accuracy of prognostic risk scores for patients with chronic heart failure (HF) has rarely been examined. We assessed the relationship between estimated probability of death and modes of death in this population, as well as the predictors of death and survival in prognostic outliers.
The MAGGIC 3-year probability of death was estimated in 6,859 participants of the GISSI-HF trial (mean age 67±11 years, 78% men, 91% with ejection fraction <40%, mean follow-up 3.5±1.3 years, observed mortality 28.4%). The incidence of SCD progressively decreased with increased probability of death, and occurred in 52.5% of patients estimated at low-risk (N = 61 with probability <14%) vs. in 23.5% of the high-risk ones (N = 375 with probability >56%, P < .0001). On the contrary, death from worsening HF was significantly more frequent in the latter group (19.7% vs. 46.1%, P < .0001). The overall predictive accuracy of the MAGGIC model improved after excluding deaths from SCD (AUC from 0.731 to 0.760, P = .0034). Among patients estimated at low-risk (N = 61 dead, 743 alive), independent predictors of death were older age, longer history of HF, higher serum uric acid and chronic obstructive pulmonary disease. The only predictor of survival in patients estimated at high-risk (N = 210 alive, 375 dead) was higher systolic blood pressure.
The MAGGIC risk score demonstrated its scarce ability to capture SCD, particularly in chronic HF patients estimated at low risk of death. Newer and better prognostic tools in the evolving horizon of HF are needed.
Journal Article
Human behavior and Homo-mammal interactions at the first European peopling: new evidence from the Pirro Nord site (Apricena, Southern Italy)
by
Karambatsou, Theodora
,
Colopi, Francesco
,
Caracausi, Sandro
in
Animals
,
Anthropogenic factors
,
Archaeology
2019
Recent functional and zooarchaeological studies conducted on the archeological finds of Pirro Nord (PN13) produced new, reliable data on early European hominid subsistence activities. The age of the site is estimated to be ~ 1.3–1.6 Ma, based on bio-chronological data, and the archeological excavation of the Pirro Nord 13 fissure led to the discovery of more than 300 lithic artifacts associated with thousands of vertebrate fossil remains of the final Villafranchian (Pirro Nord Faunal Unit). The analysis of the fossil faunal remains allowed for the identification of anthropogenic traces linked to the exploitation of different animal carcass (cut marks and intentional bone breakages). Use-wear traces were also observed on some flint artifacts and have been interpreted as the result of the exploitation of animal resources by early hominids and carnivores. It has not been possible to identify the type of access that hominins developed on the carcasses, although it has been established that the hominins competed with carnivores for animal resources. The stone tools and faunal remains with anthropogenic traces recovered in the PN13 fissure represent among the earliest evidence of hominin faunal exploitation in Europe.
Journal Article
Interleukin-6 polymorphism and Helicobacter pylori infection in Brazilian adult patients with chronic gastritis
2005
Helicobacter pylori is recognised as the most common cause of chronic active gastritis and this bacterium is also an important pathogenic factor in peptic ulcer disease. The biological factors that influence clinical outcome in H. pylori infection have been extensively studied. In addition to immunological factors in the host, bacterial virulence determinants in H. pylori strains are likely to play a crucial role in gastric cancer development. Singlenucleotide polymorphisms at the 5' flanking region of the interleukin (IL)-6 gene promoter (G or C at -174 base) have been identified and individuals with the G allele at position -174 have been shown to produce higher levels of IL-6 than those with the C/C genotype. The mucosal levels of IL-6 were reported to be increased in H. pylori-associated gastritis. The present study was conducted to examine any relationship between inflammatory cytokine polymorphisms and the inflammatory process in mucosa infected by H. pylori. In our study we did not find any association between the C and G alleles in adult patients with chronic gastritis and inflammatory process in gastric mucosa.
Journal Article
De novo design of high-affinity protein binders with AlphaProteo
2024
Computational design of protein-binding proteins is a fundamental capability with broad utility in biomedical research and biotechnology. Recent methods have made strides against some target proteins, but on-demand creation of high-affinity binders without multiple rounds of experimental testing remains an unsolved challenge. This technical report introduces AlphaProteo, a family of machine learning models for protein design, and details its performance on the de novo binder design problem. With AlphaProteo, we achieve 3- to 300-fold better binding affinities and higher experimental success rates than the best existing methods on seven target proteins. Our results suggest that AlphaProteo can generate binders \"ready-to-use\" for many research applications using only one round of medium-throughput screening and no further optimization.
Relational Forward Models for Multi-Agent Learning
by
Mediano, Pedro A M
,
Rabinowitz, Neil C
,
Tacchetti, Andrea
in
Agents (artificial intelligence)
,
Decision analysis
,
Embedded systems
2018
The behavioral dynamics of multi-agent systems have a rich and orderly structure, which can be leveraged to understand these systems, and to improve how artificial agents learn to operate in them. Here we introduce Relational Forward Models (RFM) for multi-agent learning, networks that can learn to make accurate predictions of agents' future behavior in multi-agent environments. Because these models operate on the discrete entities and relations present in the environment, they produce interpretable intermediate representations which offer insights into what drives agents' behavior, and what events mediate the intensity and valence of social interactions. Furthermore, we show that embedding RFM modules inside agents results in faster learning systems compared to non-augmented baselines. As more and more of the autonomous systems we develop and interact with become multi-agent in nature, developing richer analysis tools for characterizing how and why agents make decisions is increasingly necessary. Moreover, developing artificial agents that quickly and safely learn to coordinate with one another, and with humans in shared environments, is crucial.