1,591 research outputs found

    On the dynamics of vortex modes within magnetic islands

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    Recent work investigating the interaction of magnetic islands with micro-turbulence has uncovered the striking observation of large scale vortex modes forming within the island structure [W.A. Hornsby {\it et al.}, Phys. Plasmas {\bf 17} 092301 (2010)]. These electrostatic vortices are found to be the size of the island and are oscillatory. It is this oscillatory behaviour and the presence of turbulence that leads us to believe that the dynamics are related to the Geodesic Acoustic Mode (GAM), and it is this link that is investigated in this paper. Here we derive an equation for the GAM in the MHD limit, in the presence of a magnetic island modified three-dimensional axisymmetric geometry. The eigenvalues and eigenfunctions are calculated numerically and then utilised to analyse the dynamics of oscillatory large-scale electrostatic potential structures seen in both linear and non-linear gyro-kinetic simulations

    Bad apples in bad barrels revisited: Cognitive moral development, just world beliefs, rewards, and ethical decision-making

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    In this study, we test the interactive effect on ethical decision-making of (1) personal characteristics, and (2) personal expectancies based on perceptions of organizational rewards and punishments. Personal characteristics studied were cognitive moral development and belief in a just world. Using an in-basket simulation, we found that exposure to reward system information influenced managers' outcome expectancies. Further, outcome expectancies and belief in a just world interacted with managers' cognitive moral development to influence managers' ethical decision-making. In particular, low-cognitive moral development managers who expected that their organization condoned unethical behavior made less ethical decisions while high cognitive moral development managers became more ethical in this environment. Low cognitive moral development managers also behaved less ethically when their belief in a just world was high

    Crystal Symmetry Lowering in Chiral Multiferroic Ba3_3TaFe3_3Si2_2O14_{14} observed by X-Ray Magnetic Scattering

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    Chiral multiferroic langasites have attracted attention due to their doubly-chiral magnetic ground state within an enantiomorphic crystal. We report on a detailed resonant soft X-ray diffraction study of the multiferroic Ba3_3TaFe3_3Si2_2O14_{14} at the Fe L2,3L_{2,3} and oxygen KK edges. Below TNT_N (27K\approx27K) we observe the satellite reflections (0,0,τ)(0,0,\tau), (0,0,2τ)(0,0,2\tau), (0,0,3τ)(0,0,3\tau) and (0,0,13τ)(0,0,1-3\tau) where τ0.140±0.001\tau \approx 0.140 \pm 0.001. The dependence of the scattering intensity on X-ray polarization and azimuthal angle indicate that the odd harmonics are dominated by the out-of-plane (c^\mathbf{\hat{c}}-axis) magnetic dipole while the (0,0,2τ)(0,0,2\tau) originates from the electron density distortions accompanying magnetic order. We observe dissimilar energy dependences of the diffraction intensity of the purely magnetic odd-harmonic satellites at the Fe L3L_3 edge. Utilizing first-principles calculations, we show that this is a consequence of the loss of threefold crystal symmetry in the multiferroic phase

    Attachment and proliferation of dental pulp stem cells on dentine treated with different regenerative endodontic protocols

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    Aim To investigate the attachment and proliferation of dental pulp stem cells (DPSC) on dentine treated with various endodontic regeneration protocols. Methodology Standardized dentine samples were irrigated with sodium hypochlorite (1.5% NaOCl) and ethylenediaminetetraacetic acid (17% EDTA) and randomized into four treatment groups and two control groups. The treatment groups were treated with a clinically used concentration of triple antibiotic paste (TAP), double antibiotic paste (DAP), calcium hydroxide (Ca(OH)2) or diluted TAP in a methylcellulose system (DTAP) for 1 week. Each sample in the treatment groups was then irrigated with EDTA. The two control groups were treated with EDTA or received no treatment. Dental pulp stem cells were seeded on each dentine specimen (10 000 cells). Lactate dehydrogenase activity assays were then performed to evaluate the attached DPSC after 1 day of incubation. Water-soluble tetrazolium assays were used to determine DPSC proliferation after three additional days of incubation. Friedman's test followed by least significant difference were used for statistical analyses (α = 0.05). Results Triple antibiotic paste and DTAP regeneration protocols, as well as EDTA-treated dentine, caused significant increases in DPSC attachment to dentine. Triple antibiotic paste, DAP and Ca(OH)2 regeneration protocols caused significant reductions in DPSC proliferation on dentine. However, the DTAP regeneration protocol did not have any significant negative effects on DPSC proliferation. Conclusions The clinically used endodontic regeneration protocols that include the use of TAP, DAP or Ca(OH)2 medicament negatively affected DPSC proliferation on dentine. However, the use of DTAP medicament during regenerative endodontic treatment may not adversely affect the proliferation of DPSC

    Actinomycosis of the sigmoid colon: A case report

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    Abdominal actinomycosis is a chronic suppurative infection caused by Actinomyces species. The ileo-cecal region is most commonly affected, while the left side of the colon is more rarely involved. The infection has a tendency to infiltrate adjacent tissues and is therefore rarely confined to a single organ. Presentation may vary from non specific symptoms and signs to an acute abdomen. A computed tomography scan is helpful in identifying the inflammatory process and the organs involved. It also allows visual guidance for percutaneous drainage of abscesses, thus aiding diagnosis. Culture is difficult because of the anaerobic character and slow growth of actinomycetes. Colonoscopy is usually normal, but may shows signs of external compression. Preoperative diagnosis is rare and is established only in less than 10% of cases. In uncomplicated disease, high dose antibiotic therapy is the mainstay of treatment. Surgery is often performed because of a difficulty in diagnosis. Surgery and antibiotics are required in the case of complicated disease. Combined medical and surgical treatment achieves a cure in about 90% of cases. The authors report a case of sigmoid actinomycosis where diagnosis was made from the histology, and a review of the literature is presented

    \u3ci\u3eDasymutilla\u3c/i\u3e Ashmead (Hymenoptera, Mutillidae) in Panama: new species, sex associations and seasonal flight activity

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    A taxonomic revision of Panamanian species of the genus Dasymutilla Ashmead (Hymenoptera, Mutillidae) is presented and a key for the six species is given, all recognized from both sexes. Dasymutilla colorado Cambra, Williams and Quintero sp. nov., from central and eastern Panama, is described and illustrated. Sex associations permitted us to make the following five synonymies: D. sleipniri Manley and Pitts, 2007 (male) under D. phya (Cameron, 1895) (female); D. deyrollesi Mickel, 1937 (male) and Sphaerophthama [sic.] temaxensis Cameron, 1895 under Dasymutilla araneoides (Smith, 1862) (female); D. ionothorax Manley and Pitts, 2007 (male) under Dasymutilla spilota Manley and Pitts, 2007 (female); and D. guanacaste Manley and Pitts, 2007 (male) under D. paradoxa (Gerstaecker, 1874) (female). Seasonal flight activity for Dasymutilla from six years of continuous malaise trappings in Barro Colorado Island is presented

    Is It Time to Call Time on Bone Marrow Biopsy for Staging Ewing Sarcoma (ES)?

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    Primary malignant bone sarcomas are rare and Ewing sarcoma (ES), along with osteosarcoma, predominates in teenagers and young adults. The well-established multimodality treatment incorporates systemic chemotherapy with local control in the form of surgery, with or without radiation. The presence and extent of metastases at diagnosis remains the most important prognostic factor in determining patient outcome; patients with skeletal metastases or bone marrow infiltration having a significantly worse outcome than those with lung metastases alone. There is, however, no accepted staging algorithm for ES. Large cooperative groups and national guidelines continue to advocate bone marrow biopsy (BMB) for staging but functional imaging techniques, such as 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) with computerised tomography (CT) have been increasingly used for staging cancers and whole-body magnetic resonance imaging (WB-MRI) for staging skeletal metastases. This review outlines the current literature, from which we conclude that BMB is no longer required for the staging of ES as it does not influence the standard of care management. BMB may, however, provide prognostic information and insights into the biology of ES in selected patients on prospective clinical trials

    Psychological adaptation and recovery in youth with sarcoma: a qualitative study with practical implications for clinical care and research

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    Objectives: This study explored factors that play a role in psychological adaptation and recovery of young people with sarcoma. / Design: Qualitative study. / Setting: National Health Service hospitals in the UK. / Methods: Using purposive sampling, participants were recruited for semistructured interviews over the telephone or face to face in order to answer questions about how cancer impacted various domains of their life. Data were analysed using a framework approach. / Results: Thirty participants, aged 15–39 years with primary sarcoma diagnosis provided in-depth accounts of their experience. Emerging themes from the interviews were grouped into two overarching themes that relate to one’s adaptation to illness: individual level and environmental level. The qualitative nature of our study sheds light on meaningful connections between various factors and their role in one’s psychological adaptation to sarcoma. We devised a visual matrix to illustrate how risk and protective factors in adaptation vary between and within individuals. / Conclusions: This study demonstrates that young people with sarcoma report an array of both positive and negative factors related to their illness experience. The route to recovery is a multifactorial process and a one-size-fits-all approach to psychosocial care proves inadequate. We propose that moving beyond the latent constructs of resilience and psychopathology towards a dynamic model of psychological adaptation and recovery in this population can result in optimisation of care. We offer some recommendations for professionals working with young people with sarcoma in clinic and research

    Multiple magnetic ordering phenomena in multiferroic o-HoMnO3

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    Orthorhombic HoMnO3 is a multiferroic in which Mn antiferromagnetic order induces ferroelectricity. A second transition occurs within the multiferroic phase, in which a strong enhancement of the ferroelectric polarization occurs concomitantly to antiferromagnetic ordering of Ho 4f magnetic moments. Using the element selectivity of resonant X-ray diffraction, we study the magnetic order of the Mn 3d and Ho 4f moments. We explicitly show that the Mn magnetic order is affected by the Ho 4f magnetic ordering transition. Based on the azimuthal dependence of the (0 q 0) and (0 1-q 0) magnetic reflections, we suggest that the Ho 4f order is similar to that previously observed for Tb 4f in TbMnO3, which resembles an ac-cycloid. This is unlike the Mn order, which has already been shown to be different for the two materials. Using non-resonant diffraction, we show that the magnetically-induced ferroelectric lattice distortion is unaffected by the Ho ordering, suggesting a mechanism through which the Ho order affects polarization without affecting the lattice in the same manner as the Mn order
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