Modelling the effect of carbon on deformation behaviour of twinning induced plasticity steels

In this article, a physical model describing the deformation behaviour of Twinning Induced Plasticity(TWIP) steels has been extended to include the effect of carbon content. The experimental validation and the analysis show that carbon mainly controls the maximum number of dislocations piled up at the twin boundary, resulting in the increase of back-stresses (i.e. kinematic hardening) and therefore the work hardening rate. This explanation seems to be in agreement with recent TEM observations. © The Author(s) 2011. This article is published with open access at Springerlink.com. © Springer Science+Business Media, LLC 2011.published_or_final_versionSpringer Open Choice, 21 Feb 201

Effect of water stress on growth, water consumption and yield of silage maize under flood irrigation in semi-arid clilmate of Tadla (Morocco)

The field study of crops response to water stress is important to reduce agricultural water use in areas where the water resources are limited. This study was carried out during two growing periods of 2009 and 2010 in order to study the effect of water stress on crops growth, water consumption and dry matter yield of silage maize supplied with flood irrigation under the semiarid climate of Tadla in Morocco. Four to five irrigation treatments were applied at the rates of 100, 80, 60, 40 and 20% of ETc of maize. Soil water status, crop growth, leaf area index and above-ground biomass were measured. Results showed that growth dynamic of maize passes by three distinct phases: exponential phase, linear phase and a final phase. The irrigation deficit accelerates the senescence of the sheets and reduces the leaf area index. The maximum values of this parameter reached at flowering under the full irrigation treatment (100%ETc) are 5.1 and 4.8 in 2009 and 2010 respectively. Dry matter yields varied from 5.3 t/ha under T4 (40%ETc) to 16.4 t/ha under T1 (100% ETc) in 2009 whereas in 2010, it oscillated between 3.9 t/ha under T5 (20%ETc) to 12.5 t/ha under T1 (100%ETc). The actual evapotranspiration under T1 (100%ETc) was 478 mm and 463 mm in 2009 and 2010 respectively. According to the averaged values of two years, linear relationships have been evaluated between dry matter yield and water consumption ETa. Yield response factor (ky) for the silage maize for all growth season was 1.12

Quantum Gravitational Corrections to the Real Klein-Gordon Field in the Presence of a Minimal Length

The (D+1)-dimensional $(\beta,\beta')$-two-parameter Lorentz-covariant deformed algebra introduced by Quesne and Tkachuk [C. Quesne and V. M. Tkachuk, J. Phys. A: Math. Gen. \textbf {39}, 10909 (2006).], leads to a nonzero minimal uncertainty in position (minimal length). The Klein-Gordon equation in a (3+1)-dimensional space-time described by Quesne-Tkachuk Lorentz-covariant deformed algebra is studied in the case where $\beta'=2\beta$ up to first order over deformation parameter $\beta$. It is shown that the modified Klein-Gordon equation which contains fourth-order derivative of the wave function describes two massive particles with different masses. We have shown that physically acceptable mass states can only exist for $\beta<\frac{1}{8m^{2}c^{2}}$ which leads to an isotropic minimal length in the interval $10^{-17}m<(\bigtriangleup X^{i})_{0}<10^{-15}m$. Finally, we have shown that the above estimation of minimal length is in good agreement with the results obtained in previous investigations.Comment: 10 pages, no figur

Broad-Spectrum Antibiotic Treatment and Subsequent Childhood Type 1 Diabetes: A Nationwide Danish Cohort Study

International audienceBackground: Treatment with antibiotics in early childhood is effective for bacterial infections but may have long-term side effects. We evaluated the effect of broad-spectrum antibiotics treatment during the first two years of life in association with mode of delivery on subsequent onset of childhood type 1 diabetes.Methods: A Danish Nationwide cohort study included all singletons born during 1997-2010. Five national registers provided information on antibiotic redemption, outcome and confounders. The risk of type 1 diabetes with onset before the age of 15 years was assessed by Cox regression. A total of 858,201 singletons contributed 5,906,069 person- years, during which 1,503 children were diagnosed with type 1 diabetes.Results: Redemption of broad-spectrum antibiotics during the first two years of life was associated with an increased rate of type 1 diabetes during the following 13 years of life (HR 1.13; 95% CI 1.02 to 1.25), however, the rate was modified by mode of delivery. Broad- spectrum antibiotics were associated with an increased rate of type 1 diabetes in children delivered by either intrapartum cesarean section (HR 1.70; 95% CI 1.15 to 2.51) or prelabor cesarean section (HR 1.63; 95% CI 1.11 to 2.39), but not in vaginally delivered children. Number needed to harm was 433 and 562, respectively. The association with broad-spectrum antibiotics was not modified by parity, genetic predisposition or maternal redemption of antibiotics during pregnancy or lactation.Conclusions: Redemption of broad-spectrum antibiotics during infancy is associated with an increased risk of childhood type 1 diabetes in children delivered by cesarean section

Influence of severe plastic deformation on the precipitation hardening of a FeSiTi steel

The combined strengthening effects of grain refinement and high precipitated volume fraction (~6at.%) on the mechanical properties of FeSiTi alloy subjected to SPD processing prior to aging treatment were investigated by atom probe tomography and scanning transmission electron microscopy. It was shown that the refinement of the microstructure affects the precipitation kinetics and the spatial distribution of the secondary hardening intermetallic phase, which was observed to nucleate heterogeneously on dislocations and sub-grain boundaries. It was revealed that alloys successively subjected to these two strengthening mechanisms exhibit a lower increase in mechanical strength than a simple estimation based on the summation of the two individual strengthening mechanisms

Producing Enactable Protocols in Artificial Agent Societies

This paper draws upon our previous work [7, 16] in which we proposed the organisation of services around the concept of artificial agent societies and presented a framework for representing roles and protocols using LTSs. The agent would apply for a role in the society, which would result in its participation in a number of protocols. We advocated the use of the games-based metaphor for describing the protocols and presented a framework for assessing the admission of the agent to the society on the basis of its competence. In this work we look at the subsequent question: what information should the agent receive upon entry?. We can not provide it with the full protocol because of security and overload issues. Therefore, we choose to only provide the actions pertinent to the protocols that the role the agent applied for participates in the society. We employ branching bisimulation for producing a protocol equivalent to the original one with all actions not involving the role translated into silent (τ) actions. However, this approach sometimes results in non-enactable protocols. In this case, we need to repair the protocol by adding the role in question as a recipient to certain protocol messages that were causing the problems. We present three different approaches for repairing protocols, depending on the number of messages from the original protocol they modify. The modified protocol is adopted as the final one and the agent is given the role automaton that is derived from the branching bisimulation process

Characterization of a K+-induced conformational switch in a human telomeric DNA oligonucleotide using 2-aminopurine fluorescence

Human telomeric DNA consists of tandem repeats of the DNA sequence d(GGGTTA). Oligodeoxynucletotide telomere models such as d[A(GGGTTA)(3)GGG] (Tel22) fold in a cation-dependent manner into quadruplex structures consisting of stacked G-quartets linked by d(TTA) loops. NMR has shown that in Na(+) solutions Tel22 forms a ‘basket’ topology of four antiparallel strands; in contrast, Tel22 in K(+) solutions consists of a mixture of unknown topologies. Our previous studies on the mechanism of folding of Tel22 and similar telomere analogs utilized changes in UV absorption between 270 and 325 nm that report primarily on G-quartet formation and stacking showed that quadruplex formation occurs within milliseconds upon mixing with an appropriate cation. In the current study, we assessed the dynamics and equilibria of folding of specific loops by using Tel22 derivatives in which the dA residues were serially substituted with the fluorescent reporter base, 2-aminopurine (2-AP). Tel22 folding induced by Na(+) or K(+) assessed by changes in 2-AP fluorescence consists of at least three kinetic steps with time constants spanning a range of ms to several hundred seconds. Na(+)-dependent equilibrium titrations of Tel22 folding could be approximated as a cooperative two-state process. In contrast, K(+)-dependent folding curves were biphasic, revealing that different conformational ensembles are present in 1 mM and 30 mM K(+). This conclusion was confirmed by (1)H NMR. Molecular dynamics simulations revealed a K(+) binding pocket in Tel22 located near dA1 that is specific for the so-called hybrid-1 conformation in which strand 1 is in a parallel arrangement. The possible presence of this topologically specific binding site suggests that K(+) may play an allosteric role in regulating telomere conformation and function by modulating quadruplex tertiary structure

Virtual reality surgery simulation: A survey on patient specific solution

For surgeons, the precise anatomy structure and its dynamics are important in the surgery interaction, which is critical for generating the immersive experience in VR based surgical training applications. Presently, a normal therapeutic scheme might not be able to be straightforwardly applied to a specific patient, because the diagnostic results are based on averages, which result in a rough solution. Patient Specific Modeling (PSM), using patient-specific medical image data (e.g. CT, MRI, or Ultrasound), could deliver a computational anatomical model. It provides the potential for surgeons to practice the operation procedures for a particular patient, which will improve the accuracy of diagnosis and treatment, thus enhance the prophetic ability of VR simulation framework and raise the patient care. This paper presents a general review based on existing literature of patient specific surgical simulation on data acquisition, medical image segmentation, computational mesh generation, and soft tissue real time simulation

Effect of harvest time on physicochemical quality parameters, oxidation stability, and volatile compounds of extra virgin olive oil

The aim of this study was to determine the changes in some physicochemical properties of olives (fruit weight, water content and oil content) and olive oils (total chlorophyll, carotenoid, pheophytin a, peroxide value and free acidity), and in the chemical properties (fatty acids, tocopherols, phenolics, oxidation stability and volatile profiles) of oils during ripening.Ripening indices (RI) of olive samples were 1.93 (unripe), 4.28 (ripe) and 5.89 (overripe). Most of the mentioned features changed with ripening. During ripening there was a sharp decrease in total chlorophyll, carotenoid and pheophytin a contents. An increase in oleic and linoleic acids and a decrease in palmitic acid were found in the fatty acid composition. Olive oils showed strong relations among oxidation stability, tocopherol content, total phenols content, and antiradical actvity of phenol extracts and these parameters decreased with maturation. Nevertheless, higher amounts of trans-2-hexenal were found in the oil from ripe olives than from unripe and overripe olives. On the other hand, the highest concentration of hexanal was found in the oil from overripe olives.In general, significant differences were observed in fruit weight, pigments, free acidity, fatty acid, tocopherol, and total phenolics contents, radical scavenger activity, oxidation stability, phenolic profile and volatile profile between the olive oils from the Gemlik cultivar at different stages of maturation