Coupled phase transformations and plastic flows under torsion at high pressure in rotational diamond anvil cell: Effect of contact sliding

A three-dimensional large-sliding contact model coupled with strain-induced phase transformations (PTs) and plastic flow in a disk-like sample under torsion at high pressure in rotational diamond anvil cell (RDAC) is formulated and studied. Coulomb and plastic friction are combined and take into account variable parameters due to PT. Results are obtained for weaker, equal-strength, and stronger high pressure phases, and for three values of the kinetic coefficient in a strain-controlled kinetic equation and friction coefficient. All drawbacks typical of problem with cohesion are overcome, including eliminating mesh-dependent shear band and artificial plastic zones. Contact sliding intensifies radial plastic flow, which leads to larger reduction in sample thickness. Larger plastic strain and increased pressure in the central region lead to intensification of PT. However, the effect of the reduction in the friction coefficient on PT kinetics is nonmonotonous. Sliding increases away from the center and with growing rotation and is weakly dependent on the kinetic coefficient. Also, cyclic back and forth torsion is studied and compared to unidirectional torsion. Multiple experimental phenomena, e.g., pressure self-multiplication effect, steps (plateaus) at pressure distribution, flow to the center of a sample, and oscillatory pressure distribution for weaker high-pressure phase, are reproduced and interpreted. Reverse PT in high pressure phase that flowed to the low pressure region is revealed. Possible misinterpretation of experimental PT pressure is found. Obtained results represent essential progress toward understanding of strain-induced PTs under compression and shear in RDAC and may be used for designing experiments for synthesis of new high pressure phases and reduction in PT pressure for known phases, as well as for determination of PT kinetics from experiments

Stochastic stability versus localization in chaotic dynamical systems

We prove stochastic stability of chaotic maps for a general class of Markov random perturbations (including singular ones) satisfying some kind of mixing conditions. One of the consequences of this statement is the proof of Ulam's conjecture about the approximation of the dynamics of a chaotic system by a finite state Markov chain. Conditions under which the localization phenomenon (i.e. stabilization of singular invariant measures) takes place are also considered. Our main tools are the so called bounded variation approach combined with the ergodic theorem of Ionescu-Tulcea and Marinescu, and a random walk argument that we apply to prove the absence of ``traps'' under the action of random perturbations.Comment: 27 pages, LaTe

Plastic flows and phase transformations in materials under compression in diamond anvil cell: Effect of contact sliding

Modeling of coupled plastic flows and strain-induced phase transformations (PTs) under high pressure in a diamond anvil cell is performed with the focus on the effect of the contact sliding between sample and anvils. Finite element software ABAQUS is utilized and a combination of Coulomb friction and plastic friction is considered. Results are obtained for PTs to weaker, equal-strength, and stronger high pressure phases, using different scaling parameters in a strain-controlled kinetic equation, and with various friction coefficients. Compared to the model with cohesion, artificial shear banding near the constant surface is eliminated. Sliding and the reduction in friction coefficient intensify radial plastic flow in the entire sample (excluding a narrow region near the contact surface) and a reduction in thickness. A reduction in the frictioncoefficient to 0.1 intensifies sliding and increases pressure in the central region. Increases in both plastic strain and pressure lead to intensification of strain-induced PT. The effect of self-locking of sliding is revealed. Multiple experimental phenomena are reproduced and interpreted. Thus, plastic flow and PT can be controlled by controlling friction

Ka-band (32-GHz) performance of 70-meter antennas in the Deep Space Network

Two models are provided of the Deep Space Network (DSN) 70 m antenna performance at Ka-band (32 GHz) and, for comparison purposes, one at X-band (8.4 GHz). The baseline 70 m model represents expected X-band and Ka-band performance at the end of the currently ongoing 64 m to 70 m mechanical upgrade. The improved 70 m model represents two sets of Ka-band performance estimates (the X-band performance will not change) based on two separately developed improvement schemes: the first scheme, a mechanical approach, reduces tolerances of the panels and their settings, the reflector structure and subreflector, and the pointing and tracking system. The second, an electronic/mechanical approach, uses an array feed scheme to compensate fo lack of antenna stiffness, and improves panel settings using microwave holographic measuring techniques. Results are preliminary, due to remaining technical and cost uncertainties. However, there do not appear to be any serious difficulties in upgrading the baseline DSN 70 m antenna network to operate efficiently in an improved configuration at 32 GHz (Ka-band). This upgrade can be achieved by a conventional mechanical upgrade or by a mechanical/electronic combination. An electronically compensated array feed system is technically feasible, although it needs to be modeled and demonstrated. Similarly, the mechanical upgrade requires the development and demonstration of panel actuators, sensors, and an optical surveying system

Analysis of genetic diversity of Hyptis pectinata (L.) Poit. plants using ISSR markers.

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Genetic divergence in basil cultivars and hybrids.

Basil is an aromatic herb that stands out fo its economic importance. It is consumed in natura and sed to obtain essential oil. The cultivation of this species in several regions of the world has allowed variations by natural crosses and euploidy, leading to the wide genetic variability found nowadays. Considering the importance of this species, we aimed to analyze the genetic diversity of 27 basil genotypes using ISSR molecular markers. Fourteen primers were employed for DNA amplification, resulting in 86% polymorphism. Based on the Jaccard?s dissimilarity index, the highest index (0.80) was observed between the individuals BAS001 and BAS012, while the lowest index (0.18) was detected between the genotypes BAS014 and BAS015. The genetic similarity among individuals was calculated, forming four distinct clusters. Most individuals (40.7%) were allocated in cluster I. The polymorphic information content (PIC) (0.89) indicated considerable levels of genetic diversity among genotypes. In this sense, the ISSR markers were efficient in the detection of polymorphisms between the accessions, suggesting the genetic variability of the collection. This result demonstrates the importance of the use of molecular markers and the advantages that this information provides to the breeding of the species. O manjericão é uma erva aromática que se destaca por possuir importância econômica. É consumido in natura e também utilizado na obtenção de óleo essencial. O cultivo desta espécie em diversas regiões do mundo permitiu que surgissem variações mediante cru-zamentos naturais e euploidia, ocasionando a ampla variabilidade genética existente. Considerando a importância desta espécie, este trabalho teve como objetivo analisar a diversidade genética de 27 genótipos de manjericão usando marcadores moleculares ISSR. Qua-torze primers foram utilizados para amplificação do DNA, resultando em 86% de polimorfismo. Com base no índice de dissimilaridade de Jaccard, observou-se o maior índice (0,80) entre os indivíduos BAS001 e BAS012, enquanto que o menor índice de dissimilari-dade (0,18) foi detectado entre os genótipos BAS014 e BAS015. A semelhança genética entre indivíduos foi calculada, formando quatro grupos distintos. A maioria dos indivíduos (40,7%) foi agrupada no grupo I. O conteúdo de informação polimórfica (PIC) (0,89) indicou níveis consideráveis de diversidade genética entre os genótipos. Neste sentido, os marcadores ISSR foram eficientes na detecção de polimorfismos entre os acessos e confirmaram que é possível inferir a variabilidade genética na coleção. Isso demonstra a importância do uso de marcadores moleculares e as vantagens que esta informação pode oferecer ao melhoramento genético das espécies

Precision measurement of the half-life and the decay branches of 62Ga

In an experiment performed at the Accelerator Laboratory of the University of Jyvaskyla, the beta-decay half-life of 62Ga has been studied with high precision using the IGISOL technique. A half-life of T1/2 = 116.09(17)ms was measured. Using beta-gamma coincidences, the gamma intensity of the 954keV transition and an upper limit of the beta-decay feeding of the 0+_2 state have been extracted. The present experimental results are compared to previous measurements and their impact on our understanding of the weak interaction is discussed.Comment: 7 pages, 7 figures, submitted to EPJ

Using Touch Technology to Foster Storytelling in the Preschool Classroom

This practitioner research explores ways children engage in literacy learning through storytelling with the use of touch technology in a VPK (Voluntary Pre-Kindergarten) classroom. With access to diverse touch technology devices but no experience using these technologies, a VPK teacher explored strategies to use the resources to enhance literacy learning in the classroom with the support of a professional learning community (PLC). The PLC consisted of a master’s student, university faculty, school director, and a technology liaison. The implementation of this study took place over three weeks, and every week children created a different story. Collected data include photographs, student voice recordings, anecdotal notes, and a reflective journal. The three weeks of implementation data showed how touch technology provided a new modality of learning representation for young children in my classroom. The findings suggest that multiliteracies complemented traditional literacy, storytelling enhanced children’s communication, and touch technology functionality went beyond literacy skills