904 research outputs found
Tidal Disruptions of Main Sequence Stars of Varying Mass and Age: Inferences from the Composition of the Fallback Material
We use a simple framework to calculate the time evolution of the composition
of the fallback material onto a supermassive black hole arising from the tidal
disruption of main sequence stars. We study stars with masses between 0.8 and
3.0 , at evolutionary stages from zero-age main sequence to
terminal-age main sequence, built using the Modules for Experiments in Stellar
Astrophysics code. We show that most stars develop enhancements in nitrogen
(N) and depletions in carbon (C) and oxygen (O) over their
lifetimes, and that these features are more pronounced for higher mass stars.
We find that, in an accretion-powered tidal disruption flare, these features
become prominent only after the time of peak of the fallback rate and appear at
earlier times for stars of increasing mass. We postulate that no severe
compositional changes resulting from the fallback material should be expected
near peak for a wide range of stellar masses and, as such, are unable to
explain the extreme helium-to-hydrogen line ratios observed in some TDEs. On
the other hand, the resulting compositional changes could help explain the
presence of nitrogen-rich features, which are currently only detected after
peak. When combined with the shape of the light curve, the time evolution of
the composition of the fallback material provides a clear method to help
constrain the nature of the disrupted star. This will enable a better
characterization of the event by helping break the degeneracy between the mass
of the star and the mass of the black hole when fitting tidal disruption light
curves.Comment: 14 pages, 14 figures. Submitted to Ap
Winds in Star Clusters Drive Kolmogorov Turbulence
Intermediate and massive stars drive fast and powerful isotropic winds that
interact with the winds of nearby stars in star clusters and the surrounding
interstellar medium (ISM). Wind-ISM collisions generate astrospheres around
these stars that contain hot K gas that adiabatically expands. As
individual bubbles expand and collide they become unstable, potentially driving
turbulence in star clusters. In this paper we use hydrodynamic simulations to
model a densely populated young star cluster within a homogeneous cloud to
study stellar wind collisions with the surrounding ISM. We model a
mass-segregated cluster of 20 B-type young main sequence stars with masses
ranging from 3--17 . We evolve the winds for 11 kyrs and show
that wind-ISM collisions and over-lapping wind-blown bubbles around B-stars
mixes the hot gas and ISM material generating Kolmogorov-like turbulence on
small scales early in its evolution. We discuss how turbulence driven by
stellar winds may impact the subsequent generation of star formation in the
clusterComment: 12 pages, 5 figures, Accepted for publication in ApJ
Knowledge and Impact of COVID-19 on Middle-Aged and Older People Living with HIV in Lima, Peru
COVID-19 has had an unprecedented worldwide impact, and Peru has had one of the highest COVID-19 case rates despite implementation of an early strict nationwide quarantine. Repercussions on Peru's healthcare system may impact vulnerable populations, particularly people with HIV (PWH). We explored knowledge of COVID-19 and the socioeconomic and health impact of the pandemic among middle-aged and older PWH. A cross-sectional telephone survey was administered to 156 PWH age ≥40 years receiving care in one of two large HIV clinics in Lima, Peru. The majority of PWH (age 52 ± 7.7 years, 41% female, 65% completed secondary school or less) were knowledgeable regarding COVID-19 symptoms and prevention methods. Nearly half of those employed prior to the pandemic reported job loss. Female sex (unadjusted prevalence ratio [PR] 1.85 [95%CI 1.27-2.69]), low educational level (PR 1.62 [1.06-2.48]) and informal work (PR 1.58 [1.06-2.36]) were risk factors for unemployment but not in adjusted models. Increased anxiety was reported in 64% and stress in 77%. COVID-19 has had a substantial socioeconomic and mental health impact on PWH living in Lima, Peru, particularly those with lower educational levels and informal workers. Efforts are needed to ensure continued medical care and socioeconomic support of PWH in Peru
Multicomponent synthesis of 4,4-dimethyl sterol analogues and their effect on eukaryotic cells
Most sterols, such as cholesterol and ergosterol, become functional only after the removal of the two methyl groups at C-4 from their biosynthetic precursors. Nevertheless, some findings suggest that 4,4-dimethyl sterols might be involved in specific physiological processes. In this paper we present the synthesis of a collection of analogues of 4,4-dimethyl sterols with a diamide side chain and a preliminary analysis of their in vitro activity on selected biological systems. The key step for the synthesis involves an Ugi condensation, a versatile multicomponent reaction. Some of the new compounds showed antifungal and cytotoxic activity.Fil: Alonso, Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad de Microanálisis y Métodos Físicos en Química Orgánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Unidad de Microanálisis y Métodos Físicos en Química Orgánica; ArgentinaFil: Cirigliano, Adriana Monica. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad de Microanálisis y Métodos Físicos en Química Orgánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Unidad de Microanálisis y Métodos Físicos en Química Orgánica; ArgentinaFil: Davola, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Cabrera, Gabriela Myriam. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad de Microanálisis y Métodos Físicos en Química Orgánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Unidad de Microanálisis y Métodos Físicos en Química Orgánica; ArgentinaFil: Garcia Liñares, Guadalupe Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad de Microanálisis y Métodos Físicos en Química Orgánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Unidad de Microanálisis y Métodos Físicos en Química Orgánica; ArgentinaFil: Labriola, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Barquero, Andrea Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Ramirez, Javier Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad de Microanálisis y Métodos Físicos en Química Orgánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Unidad de Microanálisis y Métodos Físicos en Química Orgánica; Argentin
Cancer Survivors\u27 Self-Efficacy and Spirituality Outcomes Following a Holistic Integrative Intervention
Cancer treatments often negatively impact health-related quality of life (HR-QOL) for cancer survivors (CS), ignoring the multi-dimensional nature of the human experience of cancer and its impact on mental and spiritual domains. A holistic integrative approach was implemented on a heterogenous population of cancer survivors during the COVID epidemic with the goal of improving their overall well-being by looking beyond physical functioning. PURPOSE: To examine the relationship between spirituality and self-efficacy of cancer survivors of all types of cancer following a holistic intervention during the COVID-19 pandemic. METHODS: Subjects were recruited via network partners and self-referral. Subjects were eligible to participate if they were cancer survivors of any type at any stage of cancer treatment; subjects were ineligible to participate if they presented with any absolute contraindications to exercise testing as per ACSM guidelines. For 16 weeks, subjects were asked to participate in three 75-minute sessions of therapeutic yoga-based with loving kindness meditation per week. Psychosocial support text messages were sent daily to subjects based on their motivational state to encourage participation in these health enhancing behaviors. Data was collected through numerous channels including BlueJay Mobile Telehealth medicine application. RESULTS: A total of 29 survivors provided informed consent. The average age of the subjects was 58.9 years, 25 female survivors and 4 male survivors; 11 of the 29 self-reported as Latino/ Hispanic. The 29 subjects were survivors of the following primary cancers: breast cancer (n=21), cervical cancer (n=2), ovarian cancer (n=1), prostate cancer (n=1), sarcoma (n=1), lymphoma (n=1), thyroid cancer (n=1), or leukemia (n=1). There is a positive association between how confident a cancer survivor feels towards performing exercise in various situations and the amount of social support they receive from their family (p\u3c.001) and friends (p\u3c.001). The individual’s confidence to overcome the obstacle to exercise and their level of hope are associated with the support they receive from loved ones. CONCLUSION: The present study suggests that to improve exercise behavior in adult cancer survivors, one should incorporate social support to strengthen barriers self-efficacy to improve outcome expectations. To further understand these associations, longitudinal research is needed and should include more survivors
Mendelian Randomisation Confirms the Role of Y-Chromosome Loss in Alzheimer’s Disease Aetiopathogenesis in Men
Mosaic loss of chromosome Y (mLOY) is a common ageing-related somatic event and has been previously associated with Alzheimer’s disease (AD). However, mLOY estimation from genotype microarray data only reflects the mLOY degree of subjects at the moment of DNA sampling. Therefore, mLOY phenotype associations with AD can be severely age-confounded in the context of genome-wide association studies. Here, we applied Mendelian randomisation to construct an age-independent mLOY polygenic risk score (mloy-PRS) using 114 autosomal variants. The mloy-PRS instrument was associated with an 80% increase in mLOY risk per standard deviation unit (p = 4.22 × 10−20) and was orthogonal with age. We found that a higher genetic risk for mLOY was associated with faster progression to AD in men with mild cognitive impairment (hazard ratio (HR) = 1.23, p = 0.01). Importantly, mloy-PRS had no effect on AD conversion or risk in the female group, suggesting that these associations are caused by the inherent loss of the Y chromosome. Additionally, the blood mLOY phenotype in men was associated with increased cerebrospinal fluid levels of total tau and phosphorylated tau181 in subjects with mild cognitive impairment and dementia. Our results strongly suggest that mLOY is involved in AD pathogenesis.P.G.-G. (Pablo García-González) is supported by CIBERNED employment plan CNV-304-PRF-866. CIBERNED is integrated into ISCIII (Instituto de Salud Carlos III). I.d.R is supported by a national grant from the Instituto de Salud Carlos III FI20/00215. A.C. (Amanda Cano) acknowledges the support of the Spanish Ministry of Science, Innovation, and Universities under the grant Juan de la Cierva (FJC2018-036012-I). M.B. (Mercé Boada) and A.R. (Agustín Ruiz) are also supported by national grants PI13/02434, PI16/01861, PI17/01474, PI19/01240, and PI19/01301. The Genome Research @ Fundació ACE project (GR@ACE) is supported by Grifols SA, Fundación bancaria “La Caixa”, Fundació ACE, and CIBERNED. Acción Estratégica en Salud is integrated into the Spanish National R + D + I Plan and funded by ISCIII (Instituto de Salud Carlos III)—Subdirección General de Evaluación—and the Fondo Europeo de Desarrollo Regional (FEDER—“Una manera de hacer Europa”). Genotyping of the ACE MCI-EADB samples was performed in the context of EADB (European Alzheimer DNA biobank) funded by the JPco-fuND FP-829-029 (ZonMW project number 733051061). This work was supported by a grant (European Alzheimer DNA BioBank, EADB) from the EU Joint Program—Neurodegenerative Disease Research (JPND). Partial funding for open access charge: Universidad de Málag
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Rhinitis associated with asthma is distinct from rhinitis alone: TARIA‐MeDALL hypothesis
Asthma, rhinitis, and atopic dermatitis (AD) are interrelated clinical phenotypes that partly overlap in the human interactome. The concept of “one-airway-one-disease,” coined over 20 years ago, is a simplistic approach of the links between upper- and lower-airway allergic diseases. With new data, it is time to reassess the concept. This article reviews (i) the clinical observations that led to Allergic Rhinitis and its Impact on Asthma (ARIA), (ii) new insights into polysensitization and multimorbidity, (iii) advances in mHealth for novel phenotype definitions, (iv) confirmation in canonical epidemiologic studies, (v) genomic findings, (vi) treatment approaches, and (vii) novel concepts on the onset of rhinitis and multimorbidity. One recent concept, bringing together upper- and lower-airway allergic diseases with skin, gut, and neuropsychiatric multimorbidities, is the “Epithelial Barrier Hypothesis.” This review determined that the “one-airway-one-disease” concept does not always hold true and that several phenotypes of disease can be defined. These phenotypes include an extreme “allergic” (asthma) phenotype combining asthma, rhinitis, and conjunctivitis.info:eu-repo/semantics/publishedVersio
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