432 research outputs found

    Active Tension Network model suggests an exotic mechanical state realized in epithelial tissues.

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    Mechanical interactions play a crucial role in epithelial morphogenesis, yet understanding the complex mechanisms through which stress and deformation affect cell behavior remains an open problem. Here we formulate and analyze the Active Tension Network (ATN) model, which assumes that the mechanical balance of cells within a tissue is dominated by cortical tension and introduces tension-dependent active remodeling of the cortex. We find that ATNs exhibit unusual mechanical properties. Specifically, an ATN behaves as a fluid at short times, but at long times supports external tension like a solid. Furthermore, an ATN has an extensively degenerate equilibrium mechanical state associated with a discrete conformal - "isogonal" - deformation of cells. The ATN model predicts a constraint on equilibrium cell geometries, which we demonstrate to approximately hold in certain epithelial tissues. We further show that isogonal modes are observed in the fruit y embryo, accounting for the striking variability of apical areas of ventral cells and helping understand the early phase of gastrulation. Living matter realizes new and exotic mechanical states, the study of which helps to understand biological phenomena

    'Who Is You, Man?' - How are Blackness and Whiteness discussed in criticism of Hollywood films since #OscarsSoWhite?

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    In 2015, the annual Academy Awards proved highly controversial due to all twenty actors nominated for best lead and supporting roles being white. The popular news cycle following this was branded #OscarsSoWhite on social media, with a wide range of prominent actors, directors and journalists calling for greater on-screen diversity in Hollywood. Following on from these calls for diversity, this thesis aims to use this time period of 2015 - 2019 as a frame to analyze the critical reception of films released in the years after #OscarsSoWhiteexamining the language of film critics to gain some understanding of how they discuss race in their reviews. In recent years, the United States has seen a high degree of political and social turbulence, with a regime change and ideological polarization, combined with a renewed intensity of debate surround the country’s racial discourse following numerous cases of racial violence and ensuing civil unrest. This contextual backdrop makes research into the relationship between popular culture and the United States’ racial discourse societally relevant and necessary for sociological study. Using theory on Blackness, Whiteness and cultural criticism as the theoretical basis for this research, this thesis uses a critical discourse analysis of reviews written on a range of different films that have differing levels of diversity in the cast and crew made since 2015. Aiming to highlight the ways that critics discuss race, this thesis asks- how are Blackness and Whiteness discussed in criticism of Hollywood films since #OscarsSoWhite? The data analyzed comes from a wide range of both mainstream media and more specific online sources, with a concerted effort being made to include African-American publications and writers due to the lack of diversity amongst critics- the majority of them being White and male. Results show that White and Black critics talk about race in very different ways, with a key distinction being in the way that the influence of their personal experience of racial discourse shapes their perspective. Critics also unanimously recognize Hollywood’s historic lack of diversity, and criticize films that exhibit racial stereotypes and common narrative tropes. Analysis also shows the dominant position of Whiteness, which is also reflected through the lack of diversity amongst critics. This thesis concludes that whilst critical attitudes seem positive about a wider range of cultural perspectives being represented on-screen in the wake of #OscarsSoWhite, the lack of diversity amongst cultural mediators- the critics themselves- reifies the perspective of Whiteness in Hollywood criticism

    Shot Peening and Valve Fatigue

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    Early Delivery of Misfolded PrP from ER to Lysosomes by Autophagy

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    Prion diseases are linked to the accumulation of a misfolded isoform (PrPSc) of prion protein (PrP). Evidence suggests that lysosomes are degradation endpoints and sites of the accumulation of PrPSc. We questioned whether lysosomes participate in the early quality control of newly generated misfolded PrP. We found PrP carrying the disease-associated T182A mutation (Mut-PrP) was delivered to lysosomes in a Golgi-independent manner. Time-lapse live cell imaging revealed early formation and uptake of GFP-tagged Mut-PrP aggregates into LysoTracker labeled vesicles. Compared with Wt-PrP, Mut-PrP expression was associated with an elevation in several markers of the autophagy-lysosomal pathway, and it extensively colocalized with the autophagosome-specific marker, LC3B. In autophagy deficient (ATG5−/−) mouse embryonic fibroblasts, or in normal cells treated with the autophagy-inhibitor 3-MA, Mut-PrP colocalization with lysosomes was reduced to a similar extent. Additionally, 3-MA selectively impaired the degradation of insoluble Mut-PrP, resulting in an increase in protease-resistant PrP, whereas the induction of autophagy by rapamycin reduced it. These findings suggest that autophagy might function as a quality control mechanism to limit the accumulation of misfolded PrP that normally leads to the generation of PrPSc

    Anthropometric, biochemical and clinical assessment of malnutrition in Malaysian patients with advanced cirrhosis

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    <p>Abstract</p> <p>Background</p> <p>There is limited data on the nutritional status of Asian patients with various aetiologies of cirrhosis. This study aimed to determine the prevalence of malnutrition and to compare nutritional differences between various aetiologies.</p> <p>Methodology</p> <p>A cross-sectional study of adult patients with decompensated cirrhosis was conducted. Nutritional status was assessed using standard anthropometry, serum visceral proteins and subjective global assessment (SGA).</p> <p>Results</p> <p>Thirty six patients (mean age 59.8 ± 12.8 years; 66.7% males; 41.6% viral hepatitis; Child-Pugh C 55.6%) with decompensated cirrhosis were recruited. Malnutrition was prevalent in 18 (50%) patients and the mean caloric intake was low at 15.2 kcal/kg/day. SGA grade C, as compared to SGA grade B, demonstrated significantly lower anthropometric values in males (BMI 18.1 ± 1.6 vs 26.3 ± 3.5 kg/m2, p < 0.0001; MAMC 19.4 ± 1.5 vs 24.5 ± 3.6 cm, p = 0.002) and females (BMI 19.4 ± 2.7 vs 28.9 ± 4.3, p = 0.001; MAMC 18.0 ± 0.9 vs 28.1 ± 3.6, p < 0.0001), but not with visceral proteins. The SGA demonstrated a trend towards more malnutrition in Child-Pugh C compared to Child-Pugh B liver cirrhosis (40% grade C vs 25% grade C, p = 0.48). Alcoholic cirrhosis had a higher proportion of SGA grade C (41.7%) compared to viral (26.7%) and cryptogenic (28.6%) cirrhosis, but this was not statistically significant.</p> <p>Conclusion</p> <p>Significant malnutrition in Malaysian patients with advanced cirrhosis is common. Alcoholic cirrhosis may have more malnutrition compared to other aetiologies of cirrhosis.</p

    The "lessons" of the Australian "heroin shortage"

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    Heroin use causes considerable harm to individual users including dependence, fatal and nonfatal overdose, mental health problems, and blood borne virus transmission. It also adversely affects the community through drug dealing, property crime and reduced public amenity. During the mid to late 1990s in Australia the prevalence of heroin use increased as reflected in steeply rising overdose deaths. In January 2001, there were reports of an unpredicted and unprecedented reduction in heroin supply with an abrupt onset in all Australian jurisdictions. The shortage was most marked in New South Wales, the State with the largest heroin market, which saw increases in price, dramatic decreases in purity at the street level, and reductions in the ease with which injecting drug users reported being able to obtain the drug. The abrupt onset of the shortage and a subsequent dramatic reduction in overdose deaths prompted national debate about the causes of the shortage and later international debate about the policy significance of what has come to be called the "Australian heroin shortage". In this paper we summarise insights from four years' research into the causes, consequences and policy implications of the "heroin shortage"
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