470 research outputs found

    Magnetic state of plutonium ion in metallic Pu and its compounds

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    By LDA+U method with spin-orbit coupling (LDA+U+SO) the magnetic state and electronic structure have been investigated for plutonium in \delta and \alpha phases and for Pu compounds: PuN, PuCoGa5, PuRh2, PuSi2, PuTe, and PuSb. For metallic plutonium in both phases in agreement with experiment a nonmagnetic ground state was found with Pu ions in f^6 configuration with zero values of spin, orbital, and total moments. This result is determined by a strong spin-orbit coupling in 5f shell that gives in LDA calculation a pronounced splitting of 5f states on f^{5/2} and f^{7/2} subbands. A Fermi level is in a pseudogap between them, so that f^{5/2} subshell is already nearly completely filled with six electrons before Coulomb correlation effects were taken into account. The competition between spin-orbit coupling and exchange (Hund) interaction (favoring magnetic ground state) in 5f shell is so delicately balanced, that a small increase (less than 15%) of exchange interaction parameter value from J_H=0.48eV obtained in constrain LDA calculation would result in a magnetic ground state with nonzero spin and orbital moment values. For Pu compounds investigated in the present work, predominantly f^6 configuration with nonzero magnetic moments was found in PuCoGa5, PuSi2, and PuTe, while PuN, PuRh2, and PuSb have f^5 configuration with sizeable magnetic moment values. Whereas pure jj coupling scheme was found to be valid for metallic plutonium, intermediate coupling scheme is needed to describe 5f shell in Pu compounds. The results of our calculations show that both spin-orbit coupling and exchange interaction terms in the Hamiltonian must be treated in a general matrix form for Pu and its compounds.Comment: 20 pages, LaTeX; changed discussion on reference pape

    Alaska Native females: understanding body image dissatisfaction in a culturally diverse country

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    Thesis (M.Ed.) University of Alaska Fairbanks, 2013The current study was conducted to expand literature on body image dissatisfaction (BID) in Alaska Native females. As BID has been a concern for European American females, and many minority groups in America, professionals should examine all cultural groups for the presence of BID. The research was comprised of qualitative interviewing methods. Interviews were conducted with Alaska Native female participants between the ages of 18 and 23 years, attending the University of Alaska Fairbanks. Research questions addressed whether or not Alaska Native females experience BID, and if so how BID develops and manifests for this population. The study found that all participants experienced BID beginning in adolescence. The development and manifestation of BID varied on an individual basis, reflecting other research findings

    Long-Term Seizure Suppression and Optogenetic Analyses of Synaptic Connectivity in Epileptic Mice with Hippocampal Grafts of GABAergic Interneurons

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    Studies in rodent epilepsy models suggest that GABAergic interneuron progenitor grafts can reduce hyperexcitability and seizures in temporal lobe epilepsy (TLE). Although integration of the transplanted cells has been proposed as the underlying mechanism for these disease-modifying effects, prior studies have not explicitly examined cell types and synaptic mechanisms for long-term seizure suppression. To address this gap, we transplanted medial ganglionic eminence (MGE) cells from embryonic day 13.5 VGAT-Venus or VGAT-ChR2-EYFP transgenic embryos into the dentate gyrus (DG) of adult mice 2 weeks after induction of TLE with pilocarpine. Beginning 3–4 weeks after status epilepticus, we conducted continuous video-electroencephalographic recording until 90–100 d. TLE mice with bilateral MGE cell grafts in the DG had significantly fewer and milder electrographic seizures, compared with TLE controls. Immunohistochemical studies showed that the transplants contained multiple neuropeptide or calcium-binding protein-expressing interneuron types and these cells established dense terminal arborizations onto the somas, apical dendrites, and axon initial segments of dentate granule cells (GCs). A majority of the synaptic terminals formed by the transplanted cells were apposed to large postsynaptic clusters of gephyrin, indicative of mature inhibitory synaptic complexes. Functionality of these new inhibitory synapses was demonstrated by optogenetically activating VGAT-ChR2-EYFP-expressing transplanted neurons, which generated robust hyperpolarizations in GCs. These findings suggest that fetal GABAergic interneuron grafts may suppress pharmacoresistant seizures by enhancing synaptic inhibition in DG neural circuits

    Absence of system xc⁻ on immune cells invading the central nervous system alleviates experimental autoimmune encephalitis

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    Background: Multiple sclerosis (MS) is an autoimmune demyelinating disease that affects the central nervous system (CNS), leading to neurodegeneration and chronic disability. Accumulating evidence points to a key role for neuroinflammation, oxidative stress, and excitotoxicity in this degenerative process. System x(c)- or the cystine/glutamate antiporter could tie these pathological mechanisms together: its activity is enhanced by reactive oxygen species and inflammatory stimuli, and its enhancement might lead to the release of toxic amounts of glutamate, thereby triggering excitotoxicity and neurodegeneration. Methods: Semi-quantitative Western blotting served to study protein expression of xCT, the specific subunit of system x(c)-, as well as of regulators of xCT transcription, in the normal appearing white matter (NAWM) of MS patients and in the CNS and spleen of mice exposed to experimental autoimmune encephalomyelitis (EAE), an accepted mouse model of MS. We next compared the clinical course of the EAE disease, the extent of demyelination, the infiltration of immune cells and microglial activation in xCT-knockout (xCT(-/-)) mice and irradiated mice reconstituted in xCT(-/-) bone marrow (BM), to their proper wild type (xCT(+/+)) controls. Results: xCT protein expression levels were upregulated in the NAWM of MS patients and in the brain, spinal cord, and spleen of EAE mice. The pathways involved in this upregulation in NAWM of MS patients remain unresolved. Compared to xCT(+/+) mice, xCT(-/-) mice were equally susceptible to EAE, whereas mice transplanted with xCT(-/-) BM, and as such only exhibiting loss of xCT in their immune cells, were less susceptible to EAE. In none of the above-described conditions, demyelination, microglial activation, or infiltration of immune cells were affected. Conclusions: Our findings demonstrate enhancement of xCT protein expression in MS pathology and suggest that system x(c)- on immune cells invading the CNS participates to EAE. Since a total loss of system x(c)- had no net beneficial effects, these results have important implications for targeting system x(c)- for treatment of MS

    Comparative descriptions of eggs from three species of Rhodnius (Hemiptera: Reduviidae: Triatominae)

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    The authors describe and compare the morphological and ultrastructural characteristics of eggs from the three most recent described species of the genus Rhodnius Stål, 1859, which have not previously been studied. These species are Rhodnius colombiensis (Mejia, Galvão & Jurberg 1999), Rhodnius milesi (Carcavallo, Rocha, Galvão & Jurberg 2001) and Rhodnius stali (Lent, Jurberg & Galvão 1993). The results revealed that there are similarities in the exochorial architecture of optical microscopy and scanning electron microscopy; these include the predominance of hexagonal cells that are common to all Rhodnius species and variable degrees of lateral flattening, which is common not only to species of this genus, but also to the Rhodniini tribe. Differences in overall colour, the presence of a collar in R. milesi, a longitudinal bevel in R. stali and the precise length of R. colombiensis can be useful distinguishing features. As a result of this study, the key for egg identification proposed by Barata in 1981 can be updated.European Community - Chagas Disease Intervention ActivitiesCNPqCoordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES

    Determinants of ageism against older adults: a systematic review

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    Ageism is a widespread phenomenon and constitutes a significant threat to older people’s well-being. Identifying the factors contributing to ageism is critical to inform policies that minimise its societal impact. In this systematic review, we gathered and summarised empirical studies exploring the key determinants of ageism against older people for a period of over forty years (1970–2017). A comprehensive search using fourteen databases identified all published records related to the umbrella concept of “ageism”. Reviewers independently screened the final pool to identify all papers focusing on determinants, according to a predefined list of inclusion and exclusion criteria. All relevant information was extracted and summarised following a narrative synthesis approach. A total of 199 papers were included in this review. We identified a total of 14 determinants as robustly associated with ageism. Of these, 13 have an effect on other-directed ageism, and one on self-directed ageism. The quality of contact with older people and the positive or negative presentation of older people to others emerged as the most robust determinants of other-directed ageism; self-directed ageism is mostly determined by older adults’ health status. Given the correlational nature of most studies included in this review, inferences on causality should be made cautiously.info:eu-repo/semantics/publishedVersio

    Determinants of ageism against older adults: a systematic review

    Get PDF
    Ageism is a widespread phenomenon and constitutes a significant threat to older people’s well-being. Identifying the factors contributing to ageism is critical to inform policies that minimise its societal impact. In this systematic review, we gathered and summarised empirical studies exploring the key determinants of ageism against older people for a period of over forty years (1970–2017). A comprehensive search using fourteen databases identified all published records related to the umbrella concept of “ageism”. Reviewers independently screened the final pool to identify all papers focusing on determinants, according to a predefined list of inclusion and exclusion criteria. All relevant information was extracted and summarised following a narrative synthesis approach. A total of 199 papers were included in this review. We identified a total of 14 determinants as robustly associated with ageism. Of these, 13 have an effect on other-directed ageism, and one on self-directed ageism. The quality of contact with older people and the positive or negative presentation of older people to others emerged as the most robust determinants of other-directed ageism; self-directed ageism is mostly determined by older adults’ health status. Given the correlational nature of most studies included in this review, inferences on causality should be made cautiously.info:eu-repo/semantics/publishedVersio

    Patient-Reported Experiences of Supportive Cancer Care during the COVID-19 Pandemic

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    Background. During the COVID-19 pandemic, people affected by cancer were in need of information about the virus and about the (self-) management of cancer symptoms and treatment. It is important to understand how patients with cancer navigated through the pandemic and to explore their experience relating to their supportive care needs. Aim. This study aimed to describe the experience of Swiss oncological patients during the COVID-19 pandemic with additional supportive cancer care. Methods. A single-center study was conducted in 2021. Patients with melanoma, breast, lung, or colon cancer who received active systemic anticancer treatment at the time of the COVID-19 pandemic and who were additionally seeing either oncology clinical nurse specialists, integrative medicine physicians, or both were included. We conducted semistructured interviews alongside the patient-reported quantitative assessment of distress and resilience. Thematic analysis was performed for the qualitative data and descriptive statistics for the quantitative data. Results. Eighteen patients with cancer were interviewed. Patients seeing an integrative medicine physician highlighted that they positively felt being addressed as a whole person during the consultations. The oncology clinical nurse specialists were perceived as the first point of contact for the patients and had more time during the pandemic compared to what the patients normally received. In general, patients did not experience delays or disruptions in their cancer treatment. As immunosuppressed and fatigued patients with cancer, they felt supported by the restrictions and hygienic measures. Access to vaccination reassured patients against the risk of infection. These results were reflected in the quantitative data, as we found moderate distress levels (M = 4.1; SD = 2.5) and high resilience scores (M = 7.5; SD = 0.9) in this patient population. Conclusion. During the COVID-19 pandemic, patients with cancer felt particularly supported by integrative medicine and cancer nurse consultations. Secured resources for nursing consultations and integrative medicine services can help to address the supportive care needs of patients with cancer
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