2,480 research outputs found

    On the bounded cohomology of semi-simple groups, S-arithmetic groups and products

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    We prove vanishing results for Lie groups and algebraic groups (over any local field) in bounded cohomology. The main result is a vanishing below twice the rank for semi-simple groups. Related rigidity results are established for S-arithmetic groups and groups over global fields. We also establish vanishing and cohomological rigidity results for products of general locally compact groups and their lattices

    BaCu3O4: High Temperature Magnetic Order in One-Dimensional S=1/2 Diamond-Chains

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    The magnetic properties of the alkaline earth oxocuprate BaCu3O4 are investigated. We show that the characteristic Cu3O4 layers of this material can be described with diamond chains of antiferromagnetically coupled Cu 1/2 spins with only a weak coupling between two adjacent chains. These Cu3O4 layers seem to represent a so far unique system of weakly coupled one-dimensional magnetic objects where the local AF ordering of the Cu2+ ions leads to an actual net magnetic moment of an isolated diamond chain. We demonstrate a magnetic transition at a high N\'eel temperature T_{N}=336 K

    Intrinsic Low Temperature Paramagnetism in B-DNA

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    We present experimental study of magnetization in λ\lambda-DNA in conjunction with structural measurements. The results show the surprising interplay between the molecular structures and their magnetic property. In the B-DNA state, λ\lambda-DNA exhibits paramagnetic behaviour below 20 K that is non-linear in applied magnetic field whereas in the A-DNA state, remains diamagnetic down to 2 K. We propose orbital paramagnetism as the origin of the observed phenomena and discuss its relation to the existence of long range coherent transport in B-DNA at low temperature.Comment: 5 pages, 4 figures, submitted to Physical Review Letters October 200

    Factors associated with quality of life in elderly hospitalised patients undergoing post-acute rehabilitation: a cross-sectional analytical study in Switzerland.

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    We investigated whether biopsychosocial and spiritual factors and satisfaction with care were associated with patients' perceived quality of life. This was a cross-sectional analytical study. Data were collected from inpatients at a postacute geriatric rehabilitation centre in a university hospital in Switzerland. Participants aged 65 years and over were consecutively recruited from October 2014 to January 2016. Exclusion criteria included significant cognitive disorder and terminal illness. Of 227 eligible participants, complete data were collected from 167. Perceived quality of life was measured using WHO Quality of Life Questionnaire-version for older people. Predictive factors were age, sex, functional status at admission, comorbidities, cognitive status, depressive symptoms, living conditions and satisfaction with care. A secondary focus was the association between spiritual needs and quality of life. Patients undergoing geriatric rehabilitation experienced a good quality of life. Greater quality of life was significantly associated with higher functional status (r <sub>s</sub> =0.204, p=0.011), better cognitive status (r <sub>s</sub> =0.175, p=0.029) and greater satisfaction with care (r <sub>s</sub> =0.264, p=0.003). Poorer quality of life was significantly associated with comorbidities (r <sub>s</sub> =-.226, p=0.033), greater depressive symptoms (r <sub>s</sub> =-.379, p<0.001) and unmet spiritual needs ( <i>r</i> <sub>s</sub> =-.211, p=0.049). Multivariate linear regression indicated that depressive symptoms (β=-0.961; 95% CIs -1.449 to 0.472; p<0.001) significantly predicted quality of life. Patient perceptions of quality of life were significantly associated with depression. More research is needed to assess whether considering quality of life could improve care plan creation

    Nonresonant microwave absorption in epitaxial La-Sr-Mn-O films and its relation to colossal magnetoresistance

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    We study magnetic-field-dependent nonresonant microwave absorption and dispersion in thin La0.7_{0.7}Sr0.3_{0.3}MnO3_{3} films and show that it originates from the colossal magnetoresistance. We develop the model for magnetoresistance of a thin ferromagnetic film in oblique magnetic field. The model accounts fairly well for our experimental findings, as well as for results of other researchers. We demonstrate that nonresonant microwave absorption is a powerful technique that allows contactless measurement of magnetic properties of thin films, including magnetoresistance, anisotropy field and coercive field.Comment: 20 pages, 11 figure

    On the distortion of twin building lattices

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    We show that twin building lattices are undistorted in their ambient group; equivalently, the orbit map of the lattice to the product of the associated twin buildings is a quasi-isometric embedding. As a consequence, we provide an estimate of the quasi-flat rank of these lattices, which implies that there are infinitely many quasi-isometry classes of finitely presented simple groups. In an appendix, we describe how non-distortion of lattices is related to the integrability of the structural cocycle

    An information-bearing seed for nucleating algorithmic self-assembly

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    Self-assembly creates natural mineral, chemical, and biological structures of great complexity. Often, the same starting materials have the potential to form an infinite variety of distinct structures; information in a seed molecule can determine which form is grown as well as where and when. These phenomena can be exploited to program the growth of complex supramolecular structures, as demonstrated by the algorithmic self-assembly of DNA tiles. However, the lack of effective seeds has limited the reliability and yield of algorithmic crystals. Here, we present a programmable DNA origami seed that can display up to 32 distinct binding sites and demonstrate the use of seeds to nucleate three types of algorithmic crystals. In the simplest case, the starting materials are a set of tiles that can form crystalline ribbons of any width; the seed directs assembly of a chosen width with >90% yield. Increased structural diversity is obtained by using tiles that copy a binary string from layer to layer; the seed specifies the initial string and triggers growth under near-optimal conditions where the bit copying error rate is 17 kb of sequence information. In sum, this work demonstrates how DNA origami seeds enable the easy, high-yield, low-error-rate growth of algorithmic crystals as a route toward programmable bottom-up fabrication

    Fermi Velocity Spectrum and Incipient Magnetism in TiBe2

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    We address the origin of the incipient magnetism in TiBe2_2 through precise first principles calculations, which overestimate the ferromagnetic tendency and therefore require correction to account for spin fluctuations. TiBe2_2 has sharp fine structure in its electronic density of states, with a van Hove singularity only 3 meV above the Fermi level. Similarly to the isovalent weak ferromagnet ZrZn2_2, it is flat bands along the K-W-U lines of hexagonal face of the fcc Brillouin zone make the system prone to magnetism, and more so if electrons are added. We find that the Moriya BB coefficient (multiplying ωq\frac{\omega}{q} in the fluctuation susceptibility Δχ(q,ω)\Delta \chi(q,\omega)) is divergent when the velocity vanishes at a point on the Fermi surface, which is very close (3 meV) to occurring in TiBe2_2. In exploring how the FM instability (the qq=0 Stoner enhancement is S60S\approx 60) might be suppressed by fluctuations in TiBe2_2, we calculate that the Moriya A coefficient (of q2q^2) is negative, so qq=0 is not the primary instability. Explicit calculation of χo(q)\chi_o(q) shows that its maximum occurs at the X point (1,0,0)2πa(1,0,0)\frac{2\pi}{a}; TiBe2_2 is thus an incipient {\it anti}ferromagnet rather than ferromagnet as has been supposed. We further show that simple temperature smearing of the peak accounts for most of the temperature dependence of the susceptibility, which previously had been attributed to local moments (via a Curie-Weiss fit), and that energy dependence of the density of states also strongly affects the magnetic field variation of χ\chi

    Fixed points and amenability in non-positive curvature

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    Consider a proper cocompact CAT(0) space X. We give a complete algebraic characterisation of amenable groups of isometries of X. For amenable discrete subgroups, an even narrower description is derived, implying Q-linearity in the torsion-free case. We establish Levi decompositions for stabilisers of points at infinity of X, generalising the case of linear algebraic groups to Is(X). A geometric counterpart of this sheds light on the refined bordification of X (\`a la Karpelevich) and leads to a converse to the Adams-Ballmann theorem. It is further deduced that unimodular cocompact groups cannot fix any point at infinity except in the Euclidean factor; this fact is needed for the study of CAT(0) lattices. Various fixed point results are derived as illustrations.Comment: 33 page

    Validity of the FACIT-Sp to assess spiritual well-being in elderly patients

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    Among instruments measuring spiritual well-being, the Functional Assessment of Chronic Illness Therapy-Spiritual well-being (FACIT-Sp-12) is the most widely used instrument in research. It has been validated in patients suffering from cancer or HIV/AIDS, but has rarely been used in elderly patients. The objectives of this study were to determine the psychometric properties and suitability of the FACIT-Spto assess spiritual well-being in hospitalized elderly patients. This cross-sectional study uses a mixed method approach. Subjects were patients (N = 208), aged 65 years and older, consecutively admitted in post-acute rehabilitation. Psychometric properties of the FACITSp were investigated. The internal structure of the FACIT-Sp (factor structure and internal consistency) was assessed. Convergent validity of the FACIT-Sp was assessed using the Spiritual Distress Assessment Tool (SDAT), the question "Are you at peace?" and the Geriatric Depression Scale (GDS). Predictive validity was assessed using length of stay (LOS) and discharge destination. Understanding and interpretation of FACIT-Sp items were consecutively assessed in a sub-sample of 135 patients. Results show that FACIT-Sp scores ranged from 7 to 46 (mean 29.6 ± 7.8); 23.1% of the patients had high spiritual well-being. Cronbach's α was g ood ( 0.85). Item-to-total correlations were all significant (0.34 to 0.73). Principal component analyses performed with 2 or 3 factors were only moderately consistent with previous work. FACIT-Sp correlated with SDAT, "Are you at peace?" and GDS (Rho = −0.45, P < 0.001; 0.51, P < 0.001 and −0.38, P < 0.001). No association was found with LOS or discharge destination. Spontaneous comments about one or more FACIT-Sp items were made by 97/135 (71.9%). Specifically, items that address purpose and meaning in life were frequently found difficult to answer. Analyses suggest that the FACIT-Sp may underestimate spiritual well-being in older patients. In conclusion, despite having acceptable psychometric properties, the FACIT-Sp presents limitations for measurement of spiritual well-being in hospitalized elderly patients
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