81 research outputs found

    Production of triploid Sandersonia aurantiaca plants

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    Triploid plants of Sandersonia aurantiaca were produced by crossing diploid and tetraploid forms of S. aurantiaca. Enlarged ovules were transferred to in vitro culture 14–30 days after pollination. The triploid nature of the embryo derived plants was determined by flow cytometry and chromosome counts both of which showed that the triploid plants had features that were midway between those of the two parents. The mean nuclear DNA contents of 2C nuclei from diploid, triploid and tetraploid forms of S. aurantiaca were 6.86pg, 10.04pg and 13.55pg, respectively. The nuclear DNA content of 1C nuclei of sperm cells from pollen grains was 2.94pg. Mitotic chromosome counts from the three plants gave 2n = 24, 36 and 48 chromosomes for the diploid, triploid and tetraploid forms, respectively. Meiotic chromosome counts for the diploid and tetraploid plants were n = 12 and n = 24, respectively. The triploid showed mainly bivalents, but lagging chromosomes led to micronuclei and infertility in gametes. The morphological features of the various plants corroborated other evidence indicating that the triploid plants were the result of a cross between diploid and tetraploid plants

    Weak Localization Effect in Superconductors by Radiation Damage

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    Large reductions of the superconducting transition temperature TcT_{c} and the accompanying loss of the thermal electrical resistivity (electron-phonon interaction) due to radiation damage have been observed for several A15 compounds, Chevrel phase and Ternary superconductors, and NbSe2\rm{NbSe_{2}} in the high fluence regime. We examine these behaviors based on the recent theory of weak localization effect in superconductors. We find a good fitting to the experimental data. In particular, weak localization correction to the phonon-mediated interaction is derived from the density correlation function. It is shown that weak localization has a strong influence on both the phonon-mediated interaction and the electron-phonon interaction, which leads to the universal correlation of TcT_{c} and resistance ratio.Comment: 16 pages plus 3 figures, revtex, 76 references, For more information, Plesse see http://www.fen.bilkent.edu.tr/~yjki

    Extent and Causes of Chesapeake Bay Warming

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    Coastal environments such as the Chesapeake Bay have long been impacted by eutrophication stressors resulting from human activities, and these impacts are now being compounded by global warming trends. However, there are few studies documenting long-term estuarine temperature change and the relative contributions of rivers, the atmosphere, and the ocean. In this study, Chesapeake Bay warming, since 1985, is quantified using a combination of cruise observations and model outputs, and the relative contributions to that warming are estimated via numerical sensitivity experiments with a watershed–estuarine modeling system. Throughout the Bay’s main stem, similar warming rates are found at the surface and bottom between the late 1980s and late 2010s (0.02 +/- 0.02C/year, mean +/- 1 standard error), with elevated summer rates (0.04 +/- 0.01C/year) and lower rates of winter warming (0.01 +/- 0.01C/year). Most (~85%) of this estuarine warming is driven by atmospheric effects. The secondary influence of ocean warming increases with proximity to the Bay mouth, where it accounts for more than half of summer warming in bottom waters. Sea level rise has slightly reduced summer warming, and the influence of riverine warming has been limited to the heads of tidal tributaries. Future rates of warming in Chesapeake Bay will depend not only on global atmospheric trends, but also on regional circulation patterns in mid-Atlantic waters, which are currently warming faster than the atmosphere. Supporting model data available at: https://doi.org/10.25773/c774-a36

    The Status of EMDR Therapy in the Treatment of Posttraumatic Stress Disorder 30 Years After Its Introduction

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    Given that 2019 marks the 30th anniversary of eye movement desensitization and reprocessing (EMDR) therapy, the purpose of this article is to summarize the current empirical evidence in support of EMDR therapy as an effective treatment intervention for posttraumatic stress disorder (PTSD). Currently, there are more than 30 randomized controlled trials (RCT) demonstrating the effectiveness in patients with this debilitating mental health condition, thus providing a robust evidence base for EMDR therapy as a first-choice treatment for PTSD. Results from several meta-analyses further suggest that EMDR therapy is equally effective as its most important trauma-focused comparator, that is, trauma-focused cognitive behavioral therapy, albeit there are indications from some studies that EMDR therapy might be more efficient and cost-effective. There is emerging evidence showing that EMDR treatment of patients with psychiatric disorders, such as psychosis, in which PTSD is comorbid, is also safe, effective, and efficacious. In addition to future well-crafted RCTs in areas such as combat-related PTSD and psychiatric disorders with comorbid PTSD, RCTs with PTSD as the primary diagnosis remain pivotal in further demonstrating EMDR therapy as a robust treatment intervention

    Enhanced multiscale modeling of macroscopic and microscopic residual stresses evolution during multi-thermo-mechanical processes

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    After several decades, it is still difficult to predict macroscopic and microscopic (M-m) residual stresses (RSes) in metal matrix composites (MMCs) after welding. In this work, an enhanced multiscale model is developed to predict the evolution of M-m RSes in MMCs during several thermo-mechanical processes including welding. This multiscale model is capable of handling non-zero initial M-m RSes and integrates the temperature history dependent constitutive model (THDCM) at both macroscale and microscale. Meanwhile, thermal source model of friction stir welding (FSW) is integrated. The extension to other welding thermal source is straightforward. This multiscale model is used to study the generation, inheritance, and evolution of M-m RSes in a SiC/Al composite during quenching, FSW and pos t-welding heat treatment (PWHT). The effects of initial M-m RSes and material constitutive models on the prediction of M-m RSes are systematically assessed. It is found that using the THDCM and taking into account the initial RSes, this multiscale model shows the best predictions of RSes in the FSW joint of MMCs. The predictions agree with the neutron diffraction measurements reasonably well. It is found that the reduction of RSes during PWHT is mainly caused by the stress relaxation during the solution treatment stage

    The Current Status of EMDR Therapy Involving the Treatment of Complex Posttraumatic Stress Disorder

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    Complex posttraumatic stress disorder (CPTSD) is a diagnostic entity that will be included in the forthcoming edition of the International Classification of Diseases, 11th Revision (ICD-11). It denotes a severe form of PTSD, comprising not only the symptom clusters of PTSD (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition [DSM-IV-TR]), but also clusters reflecting difficulties in regulating emotions, disturbances in relational capacities, and adversely affected belief systems about oneself, others, or the world. Evidence is mounting suggesting that first-line trauma-focused treatments, including eye movement desensitization and reprocessing (EMDR) therapy, are effective not only for the treatment of PTSD, but also for the treatment of patients with a history of early childhood interpersonal trauma who are suffering from symptoms characteristic of CPTSD. However, controversy exists as to when EMDR therapy should be offered to people with CPTSD. This article reviews the evidence in support of EMDR therapy as a first-line treatment for CPTSD and addresses the fact that there appears to be little empirical evidence supporting the view that there should be a stabilization phase prior to trauma processing in working with CPTSD

    Effects of welding speed on the multiscale residual stresses in friction stir welded metal matrix composites

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    The effects of welding speed on the macroscopic and microscopic residual stresses (RSes) in friction stir welded 17 vol.% SiCp/2009Al-T4 composite plates were studied via neutron diffraction and an improved decoupled hierarchical multiscale modeling methods. Measurements showed that the macroscopic and total RSes had the largest variations in the longitudinal direction (LD). Increasing the welding speed led to higher values of measured LD macroscopic and total RSes in the matrix. The welding speed also significantly influenced the distributions and magnitudes of the microscopic RSes. The RSes were predicted via an improved hierarchical multiscale model, which includes a constant coefficient of friction based thermal model. The RSes in the composite plates before friction stir welding (FSW) were computed and then set as the initial states of the FSW process during modeling. This improved decoupled multiscale model provided improved predictions of the temperature and RSes compared with our previous model
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