Delikli Kompozit Yapıların Sonlu Elemanlar Yöntemiyle Analizi

Konferans Bildirisi -- Teorik ve Uygulamalı Mekanik Türk Milli Komitesi, 2015Conference Paper -- Theoretical and Applied Mechanical Turkish National Committee, 2015Burada delikli ileri kompozit yapılarda hasarın doğru tahmini için yapılan bir çalışmanın sonuçları sunulmuştur. Çalışmanın ilk bölümünde, kullanılan kompozitlerin ilgili mekanik özelliklerini belirlemek için kupon ve çatlak ilerleme testlerinden oluşan bir malzeme test programı yürütülmüştür. Daha sonra, delikli kompozit yapıları incelemek için bir sonlu elemanlar analizi modeli oluşturulmuştur. Sürekli ortam kabuk elemanları (continuum shell) kullanarak delaminasyonu (tabaka ayrılmasını) hesaba katan ve katmayan sonlu eleman modelleri oluşturuldu. Gerçekçi bir simülasyon elde edebilmek için ilerlemeli hasar analizi yapılmıştır. En uygun modeli belirlemek amacıyla, test sonuçları ve simülasyonlardan elde edilen sonuçlar ayrıntılı olarak tartışılmıştır.The results of a study for the prediction of failure behavior in advanced composite structures with holes are presented here. In the first part of the study, a materials test program based on coupon and fracture tests is conducted to obtain related mechanical properties. A finite element model is then constructed for simulating the behavior of advanced composite laminates with hole under tension. Two finite element models using continuum shell elements, one with and the other without the delamination failure were developed. In order to have a realistic simulation, the progressive failure analysis is applied. For an optimum model, test results and simulation results are discussed, thoroughly

Learning Foveated Reconstruction to Preserve Perceived Image Statistics

Foveated image reconstruction recovers full image from a sparse set of samples distributed according to the human visual system's retinal sensitivity that rapidly drops with eccentricity. Recently, the use of Generative Adversarial Networks was shown to be a promising solution for such a task as they can successfully hallucinate missing image information. Like for other supervised learning approaches, also for this one, the definition of the loss function and training strategy heavily influences the output quality. In this work, we pose the question of how to efficiently guide the training of foveated reconstruction techniques such that they are fully aware of the human visual system's capabilities and limitations, and therefore, reconstruct visually important image features. Due to the nature of GAN-based solutions, we concentrate on the human's sensitivity to hallucination for different input sample densities. We present new psychophysical experiments, a dataset, and a procedure for training foveated image reconstruction. The strategy provides flexibility to the generator network by penalizing only perceptually important deviations in the output. As a result, the method aims to preserve perceived image statistics rather than natural image statistics. We evaluate our strategy and compare it to alternative solutions using a newly trained objective metric and user experiments

Various Correlations in Anisotropic Heisenberg XYZ Model with Dzyaloshinski-Moriya Interaction

Various thermal correlations as well as the effect of intrinsic decoherence on the correlations are studied in a two-qubit Heisenberg XYZ spin chain with the Dzyaloshinski--Moriya (DM) interaction along the z direction, i.e. Dz. It is found that tunable parameter Dz may play a constructive role on the concurrence (C), classical correlation (CC) and quantum discord (QD) in thermal equilibrium while it plays a destructive role on the correlations in the intrinsic decoherence case. The entanglement and quantum discord exhibit collapse and revival under the phase decoherence. With a proper combination of the system parameters, the correlations can effectively be kept at high steady state values despite the intrinsic decoherence.Comment: 4 pages, 4 figure

Moving Women of Color from Reliable Voters to Candidates for Public Office

In recent presidential elections, women, people of color, millennials, and new immigrants shaped the outcomes of those elections. Women of color standing at the nexus of two underrepresented groups in politics- racial minorities and women- demonstrated their commitments to democracy by maintaining their traditions as reliable voters, far exceeding expectations. In this project, we ask what is necessary to move these women of color from reliable voters to candidates for political office and locate our answer with women of color. They are doing much of the work to deepen democratic engagement in communities of color, namely mobilizing voters and political candidates. They are redefining democratic inclusion, reshaping the electorate, and they stand to change the demographics of voters and officeholders alike. Likewise, they are redefining and disrupting traditional notions of political actors. How and why they see this as important work for themselves and their communities helps us to understand how people challenge exclusions and make a place for themselves, particularly in the political sphere which is marked by white, male dominance. Scholars have not documented this significant role women of color are playing in extending democracy and this documentation is critical to preserving women of color’s historic contributions to formal electoral politics. While the existing scholarship is rich in denoting the propensity of women of color to act as social change agents, we lag behind in scholarship recognizing the richness of their contributions to formal electoral politics. Their contributions deserve to be recorded and linked to the long line of scholarly engagements with women of color activism and leadership. We begin the project by establishing the landscape of existing WOC organizations, civic groups, collaborations and projects engaged in this work including the full landscape of programs, initiatives and organizations seeking to mobilize women of color as voters and political candidates. We explore their origin stories and contributions to civic engagement of marginalized groups. Our long term goals of the project are to strengthen the capacity of these organizations by bringing attention to their contributions; sharing best practices across groups that are not currently networked; and to leverage resources to strengthen their capacities

Increasing Notch signaling antagonizes PRC2-mediated silencing to promote reprograming of germ cells into neurons

Cell-fate reprograming is at the heart of development, yet very little is known about the molecular mechanisms promoting or inhibiting reprograming in intact organisms. In the C. elegans germline, reprograming germ cells into somatic cells requires chromatin perturbation. Here, we describe that such reprograming is facilitated by GLP-1/Notch signaling pathway. This is surprising, since this pathway is best known for maintaining undifferentiated germline stem cells/progenitors. Through a combination of genetics, tissue-specific transcriptome analysis, and functional studies of candidate genes, we uncovered a possible explanation for this unexpected role of GLP-1/Notch. We propose that GLP-1/Notch promotes reprograming by activating specific genes, silenced by the Polycomb repressive complex 2 (PRC2), and identify the conserved histone demethylase UTX-1 as a crucial GLP-1/Notch target facilitating reprograming. These findings have wide implications, ranging from development to diseases associated with abnormal Notch signaling

Neuronal inhibition of the autophagy nucleation complex extends life span in post-reproductive C. elegans

Autophagy is a ubiquitous catabolic process that causes cellular bulk degradation of cytoplasmic components and is generally associated with positive effects on health and longevity. Inactivation of autophagy has been linked with detrimental effects on cells and organisms. The antagonistic pleiotropy theory postulates that some fitness-promoting genes during youth are harmful during aging. On this basis, we examined genes mediating post-reproductive longevity using an RNAi screen. From this screen, we identified 30 novel regulators of post-reproductive longevity, including pha-4 Through downstream analysis of pha-4, we identified that the inactivation of genes governing the early stages of autophagy up until the stage of vesicle nucleation, such as bec-1, strongly extend both life span and health span. Furthermore, our data demonstrate that the improvements in health and longevity are mediated through the neurons, resulting in reduced neurodegeneration and sarcopenia. We propose that autophagy switches from advantageous to harmful in the context of an age-associated dysfunction

Patterns in the relationship between life expectancy and gross domestic product in Russia in 2005-15: a cross-sectional analysis.

BACKGROUND: Since 2005, Russia has made substantial progress, experiencing an almost doubling of per-capita gross domestic product by purchasing power parity (GDP [PPP]) to US$24 800 and witnessing a 6-year increase in life expectancy, reaching 71·4 years by 2015. Even greater gains in GDP (PPP) were seen for Moscow, the Russian capital, reaching$43 000 in 2015 and with a life expectancy of 75·5 years. We aimed to investigate whether mortality levels now seen in Russia are consistent with what would be expected given this new level of per-capita wealth. METHODS: We used per-capita GDP (PPP) and life expectancy from 61 countries in 2014-15, plus those of Russia as a whole and its capital Moscow, to construct a Preston curve expressing the relationship between mortality and national wealth and to examine the positions of Russia and other populations relative to this curve. We adjusted life expectancy values for Moscow for underestimation of mortality at older ages. For comparison, we constructed another Preston curve based on the same set of countries for the year 2005. We used the stepwise replacement algorithm to decompose mortality differences between Russia or Moscow and comparator countries with similar incomes into age and cause-of-death components. FINDINGS: Life expectancy in 2015 for both Russia and Moscow lay below the Preston-curve-based expectations by 6·5 years and 4·9 years, respectively. In 2015, Russia had a lower per-capita income than 36 of the comparator countries but lower life expectancy than 60 comparator countries. However, the gaps between the observed and the Preston-expected life expectancy values for Russia have diminished by about 25% since 2005, when the life expectancy gap was 8·9 years for Russia and 6·6 years for Moscow. When compared with countries with similar level of income, the largest part of the life expectancy deficit was produced by working-age mortality from external causes for Russia and cardiovascular disease at older ages for Moscow. INTERPRETATION: Given the economic wealth of Russia, its life expectancy could be substantially higher. Sustaining the progress seen over the past decade depends on the ability of the Russian Government and society to devote adequate resources to people's health. FUNDING: This work was partly funded through the International Project on Cardiovascular Disease in Russia supported by a Wellcome Trust Strategic Award (100217) and was supported by the Russian Academic Excellence Project 5-100

The CONJUDOR pipeline for multiplexed knockdown of gene pairs identifies RBBP-5 as a germ cell reprogramming barrier in C. elegans

Multiple gene activities control complex biological processes such as cell fate specification during development and cellular reprogramming. Investigating the manifold gene functions in biological systems requires also simultaneous depletion of two or more gene activities. RNA interference-mediated knockdown (RNAi) is commonly used in Caenorhabditis elegans to assess essential genes, which otherwise lead to lethality or developmental arrest upon full knockout. RNAi application is straightforward by feeding worms with RNAi plasmid-containing bacteria. However, the general approach of mixing bacterial RNAi clones to deplete two genes simultaneously often yields poor results. To address this issue, we developed a bacterial conjugation-mediated double RNAi technique 'CONJUDOR'. It allows combining RNAi bacteria for robust double RNAi with high-throughput. To demonstrate the power of CONJUDOR for large scale double RNAi screens we conjugated RNAi against the histone chaperone gene lin-53 with more than 700 other chromatin factor genes. Thereby, we identified the Set1/MLL methyltransferase complex member RBBP-5 as a novel germ cell reprogramming barrier. Our findings demonstrate that CONJUDOR increases efficiency and versatility of RNAi screens to examine interconnected biological processes in C. elegans with high-throughput

FACT sets a barrier for cell fate reprogramming in Caenorhabditis elegans and human cells

The chromatin regulator FACT (facilitates chromatin transcription) is essential for ensuring stable gene expression by promoting transcription. In a genetic screen using Caenorhabditis elegans, we identified that FACT maintains cell identities and acts as a barrier for transcription factor-mediated cell fate reprogramming. Strikingly, FACT's role as a barrier to cell fate conversion is conserved in humans as we show that FACT depletion enhances reprogramming of fibroblasts. Such activity is unexpected because FACT is known as a positive regulator of gene expression, and previously described reprogramming barriers typically repress gene expression. While FACT depletion in human fibroblasts results in decreased expression of many genes, a number of FACT-occupied genes, including reprogramming-promoting factors, show increased expression upon FACT depletion, suggesting a repressive function of FACT. Our findings identify FACT as a cellular reprogramming barrier in C. elegans and humans, revealing an evolutionarily conserved mechanism for cell fate protection

Proteomic and transcriptomic changes in hibernating grizzly bears reveal metabolic and signaling pathways that protect against muscle atrophy

Muscle atrophy is a physiological response to disuse and malnutrition, but hibernating bears are largely resistant to this phenomenon. Unlike other mammals, they efficiently reabsorb amino acids from urine, periodically activate muscle contraction, and their adipocytes differentially responds to insulin. The contribution of myocytes to the reduced atrophy remains largely unknown. Here we show how metabolism and atrophy signaling are regulated in skeletal muscle of hibernating grizzly bear. Metabolic modeling of proteomic changes suggests an autonomous increase of non-essential amino acids (NEAA) in muscle and treatment of differentiated myoblasts with NEAA is sufficient to induce hypertrophy. Our comparison of gene expression in hibernation versus muscle atrophy identified several genes differentially regulated during hibernation, including Pdk4 and Serpinf1. Their trophic effects extend to myoblasts from non-hibernating species (including C. elegans), as documented by a knockdown approach. Together, these changes reflect evolutionary favored adaptations that, once translated to the clinics, could help improve atrophy treatment