3,363 research outputs found

    Post-AGB Stars in Globular Clusters and Galactic Halos

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    We discuss three aspects of post-AGB (PAGB) stars in old populations. (1) HST photometry of the nucleus of the planetary nebula (PN) K 648 in the globular cluster (GC) M15 implies a mass of 0.60 Msun, in contrast to the mean masses of white dwarfs in GCs of ~0.5 Msun. This suggests that K 648 is descended from a merged binary, and we infer that single Pop II stars do not produce visible PNe. (2) Yellow PAGB stars are the visually brightest stars in old populations (Mv ~ -3.3) and are easily recognizable because of their large Balmer jumps; thus they show great promise as a Pop II standard candle. Two yellow PAGB stars in the GC NGC 5986 have the same V magnitudes to within +/-0.05 mag, supporting an expected narrow luminosity function. (3) Using CCD photometry and a u filter lying below the Balmer jump, we have detected yellow PAGB stars in the halo of M31 and in its dwarf elliptical companion NGC 205. With the Milky Way zero point, we reproduce the Cepheid distance to M31, and find that NGC 205 is ~100 kpc further away than M31. The star counts imply a yellow PAGB lifetime of about 25,000 yr, and their luminosities imply masses near 0.53 Msun.Comment: 6 pages, 2 figures. To appear in proceedings of Torun, Poland, workshop on "Post-AGB Objects (Proto-Planetary Nebulae) as a Phase of Stellar Evolution," ed. S.K. Gorn

    Finite-temperature Gutzwiller projection for strongly correlated electron systems

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    We generalized the Gutzwiller projectional variational method for the ground state of strongly correlated electron systems to the case of finite temperature. Under the Gutzwiller approximation, we show that this maps to a finite temperature renormalized mean-field theory. As one of the key ingredients in the theory, we obtained an explicit expression of the projection entropy or the entropy change due to the projection. We illustrate the application of the theory to the Anderson impurity problem and the half-filled Hubbard model and compare the theory to more elaborate techniques. We find qualitative agreement. The theory can be applied to a wide variety of Hubbard, t-J, and Anderson impurity models. © 2010 The American Physical Society.published_or_final_versio

    Use of Optical Genome Mapping to Detect Structural Variants in Neuroblastoma

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    \ua9 2023 by the authors.Background: Neuroblastoma is the most common extracranial solid tumour in children, accounting for 15% of paediatric cancer deaths. Multiple genetic abnormalities have been identified as prognostically significant in neuroblastoma patients. Optical genome mapping (OGM) is a novel cytogenetic technique used to detect structural variants, which has not previously been tested in neuroblastoma. We used OGM to identify copy number and structural variants (SVs) in neuroblastoma which may have been missed by standard cytogenetic techniques. Methods: Five neuroblastoma cell lines (SH-SY5Y, NBLW, GI-ME-N, NB1691 and SK-N-BE2(C)) and two neuroblastoma tumours were analysed using OGM with the Bionano Saphyr\uae instrument. The results were analysed using Bionano Access software and compared to previous genetic analyses including G-band karyotyping, FISH (fluorescent in situ hybridisation), single-nucleotide polymorphism (SNP) array and RNA fusion panels for cell lines, and SNP arrays and whole genome sequencing (WGS) for tumours. Results: OGM detected copy number abnormalities found using previous methods and provided estimates for absolute copy numbers of amplified genes. OGM identified novel SVs, including fusion genes in two cell lines of potential clinical significance. Conclusions: OGM can reliably detect clinically significant structural and copy number variations in a single test. OGM may prove to be more time- and cost-effective than current standard cytogenetic techniques for neuroblastoma

    Cyberbullying and eating disorder symptoms in US early adolescents

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    Objective: The objective of this study was to determine the association between cyberbullying and eating disorder symptoms in a national sample of 10–14-year-old early adolescents. / Method: We analyzed cross-sectional data from the Adolescent Brain Cognitive Development (ABCD) Study (Year 2, 2018–2020, N = 10,258/11,875, 49% female, 46% non-White). Data were collected using multi-stage probability sampling. Modified Poisson regression analyses examined the association between cyberbullying and self-reported eating disorder symptoms based on the Kiddie Schedule for Affective Disorders and Schizophrenia (KSADS-5). / Results: Cyberbullying victimization was associated with worry about weight gain (prevalence ratio [PR] 2.41, 95% confidence interval [CI] 1.48–3.91), self-worth tied to weight (PR 2.08, 95% CI 1.33–3.26), inappropriate compensatory behavior to prevent weight gain (PR 1.95, 95% CI 1.57–2.42), binge eating (PR 1.95, 95% CI 1.59–2.39), and distress with binge eating (PR 2.64, 95% CI 1.94–3.59), in models adjusting for potential confounders. Cyberbullying perpetration was associated with worry about weight gain (PR 3.52, 95% CI 1.19–10.37), self-worth tied to weight (PR 5.59, 95% CI 2.56–12.20), binge eating (PR 2.36, 95% CI 1.44–3.87), and distress with binge eating (PR 2.84, 95% CI 1.47–5.49). / Discussion: Cyberbullying victimization and perpetration in early adolescence are associated with eating disorder symptoms. Clinicians may consider assessing for cyberbullying and eating disorder symptoms in early adolescence and provide anticipatory guidance. / Public Significance Statement: Eating disorders often onset in adolescence and have among the highest mortality rates of any psychiatric disorder. In addition, cyberbullying has increased in prevalence among adolescents and significantly impacts mental health. In a national study of early adolescents, we found that cyberbullying victimization and perpetration are associated with eating disorder symptoms. Screening for and providing anticipatory guidance on cyberbullying and eating disorder symptoms in early adolescents may be warranted

    Cattle management practices and milk production on mixed smallholder organic pineapple farms in Central Uganda

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    A longitudinal study to assess animal management practices and milk production was conducted for a period of 12 months on 30 smallholder farms keeping dairy cattle and certified organic pineapple production in Luwero and Kayunga districts, based on questionnaire and on-farm collected data. Farm sizes were 9.3 ± 6.7 acres in tethering system and 4.3 ± 2.6 acres in zero-grazing. Fifty-four percent of the zero-grazing herds had animal housing facilities. All farmers in tethering system kept cows on earthen floors and calves without bedding. Hygiene level in existing farms was low. Majority of calves were fed once a day by restricted suckling (77 %). Seventy-four percent of tethered cows were only fed on natural grass, while cows under zero-grazing system had a more diversified diet but with 82 % feeding mainly Napier grass. Most farms (87 %) used bulls for breeding. Milk production was higher (P < 0.05) in zero-grazing (6.5 L/cow/day) than tethering system, and higher (P < 0.05) for Holstein-Friesian crossbred cows (5.2 L/cow/day) than local breed cows (2.6 L/cow/day). Less than 1 L of milk per farm per day on average was sold. Disease treatments were exclusively for helminths, East Coast fever, and trypanasomiasis. Spraying of ticks and deworming were important control measures of vector-borne diseases. There is potential to develop alternative feed resources for dairy cattle and biorational pesticides for control and treatment of vector-borne diseases

    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

    Ethnic differences in mental health among incarcerated youths: do Moroccan immigrant boys show less psychopathology than native Dutch boys?

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    Psychiatric disorders are highly prevalent among incarcerated youth. However, whereas ethnic minority youths are overrepresented in the juvenile justice system, limited research is available on their mental health. In this study, differences in mental health problems between incarcerated adolescents of native Dutch and Moroccan origin, were examined. Child Behavior Checklist and Youth Self-Report scores were compared between incarcerated adolescents of native Dutch and Moroccan origin. Their scores were also compared to those of native Dutch and Moroccan immigrant youths in the general, non-incarcerated population. Native Dutch incarcerated adolescents showed higher levels of various mental health problems than incarcerated adolescents with a Moroccan background. Compared to the general population, incarcerated youths showed higher levels of mental health problems, but this deviation was much larger for native Dutch than for Moroccan immigrant youths. These ethnic differences in mental health problems could not be explained by ethnic differences in socio-economic background and social desirable answering tendencies. Incarcerated youths of Moroccan origin show less psychopathology than incarcerated native Dutch youths, which might be explained by disparities in sentencing procedures

    Applying refinement to the use of mice and rats in rheumatoid arthritis research

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    Rheumatoid arthritis (RA) is a painful, chronic disorder and there is currently an unmet need for effective therapies that will benefit a wide range of patients. The research and development process for therapies and treatments currently involves in vivo studies, which have the potential to cause discomfort, pain or distress. This Working Group report focuses on identifying causes of suffering within commonly used mouse and rat ‘models’ of RA, describing practical refinements to help reduce suffering and improve welfare without compromising the scientific objectives. The report also discusses other, relevant topics including identifying and minimising sources of variation within in vivo RA studies, the potential to provide pain relief including analgesia, welfare assessment, humane endpoints, reporting standards and the potential to replace animals in RA research

    Clostridium difficile ribotypes in Austria: a multicenter, hospital-based survey

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    A prospective, noninterventional survey was conducted among Clostridium difficile positive patients identified in the time period of July until October 2012 in 18 hospitals distributed across all nine Austrian provinces. Participating hospitals were asked to send stool samples or isolates from ten successive patients with C.difficile infection to the National Clostridium difficile Reference Laboratory at the Austrian Agency for Health and Food Safety for PCR-ribotyping and in vitro susceptibility testing. A total of 171 eligible patients were identified, including 73 patients with toxin-positive stool specimens and 98 patients from which C. difficile isolates were provided. Of the 159 patients with known age, 127 (74.3 %) were 65 years or older, the median age was 76 years (range: 9–97 years), and the male to female ratio 2.2. Among these patients, 73 % had health care-associated and 20 % community-acquired C. difficile infection (indeterminable 7 %). The all-cause, 30-day mortality was 8.8 % (15/171). Stool samples yielded 46 different PCR-ribotypes, of which ribotypes 027 (20 %), 014 (15.8 %), 053 (10.5 %), 078 (5.3 %), and 002 (4.7 %) were the five most prevalent. Ribotype 027 was found only in the provinces Vienna, Burgenland, and Lower Austria. Severe outcome of C. difficile infection was found to be associated with ribotype 053 (prevalence ratio: 3.04; 95 % CI: 1.24, 7.44), not with the so-called hypervirulent ribotypes 027 and 078. All 027 and 053 isolates exhibited in vitro resistance against moxifloxacin. Fluoroquinolone use in the health care setting must be considered as a factor favoring the spread of these fluoroquinolone resistant C. difficile clones
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