4,501 research outputs found
Viele Pakistaner kennen keinen Staat: die Hochwasserkatastrophe könnte den Ruf nach Reformen der politischen und administrativen Strukturen laut werden lassen
Die Überforderung des pakistanischen Staats angesichts der Hochwasserkatastrophe ist auch eine Folge von dessen zentralistischer Organisation. Ein Versuch, lokale Strukturen aufzubauen, wurde unter der neuen Regierung abgebrochen
Decentralisation meets local complexity: local struggles, state decentralisation and access to natural resources in South Asia and Latin America
Spin Liquid State in an Organic Mott Insulator with Triangular Lattice
H NMR and static susceptibility measurements have been performed in an
organic Mott insulator with nearly isotropic triangular lattice,
-(BEDT-TTF)Cu(CN), which is a model system of
frustrated quantum spins. The static susceptibility is described by the spin
= 1/2 antiferromagnetic triangular-lattice Heisenberg model with the
exchange constant 250 K. Regardless of the large magnetic
interactions, the H NMR spectra show no indication of long-range magnetic
ordering down to 32 mK, which is four-orders of magnitude smaller than .
These results suggest that a quantum spin liquid state is realized in the close
proximity of the superconducting state appearing under pressure.Comment: 4 pages, 4 figure
Coherent vs incoherent interlayer transport in layered metals
The magnetic-field, temperature, and angular dependence of the interlayer
magnetoresistance of two different quasi-two-dimensional (2D) organic
superconductors is reported. For -(BEDT-TTF)I we find a
well-resolved peak in the angle-dependent magnetoresistance at (field parallel to the layers). This clear-cut proof for the coherent
nature of the interlayer transport is absent for
''-(BEDT-TTF)SFCHCFSO. This and the non-metallic
behavior of the magnetoresistance suggest an incoherent quasiparticle motion
for the latter 2D metal.Comment: 4 pages, 4 figures. Phys. Rev. B, in pres
Bosentan therapy for chronic thromboembolic pulmonary hypertension. A national open label study assessing the effect of Bosentan on haemodynamics, exercise capacity, quality of life, safety and tolerability in patients with chronic thromboembolic pulmonary hypertension (BOCTEPH-Study).
we performed an open-label national study to evaluate the effects of Bosentan on haemodynamics, exercise capacity, quality of life, safety and tolerability in patients with chronic thromboembolic pulmonary hypertension (CTEPH).
fifteen patients with CTEPH not eligible or waiting for surgery were enrolled. The primary endpoint was the change in pulmonary vascular resistance (PVR). Secondary endpoints included quality of life (measured by the Minnesota living with heart failure questionnaire, MLHF), 6 minute walk distance (6MWD), World Health Organization (WHO) functional class, Borg dyspnoea scale, plasma endothelin, serum values of disease severity such as uric acid, N-terminal-pro brain natriuretic peptide (NTproBNP), C-reactive protein measured by a highly sensitive method (CRPs) and other serum and haemodynamic parameters.
after six months of treatment with bosentan, the PVR decreased from 852 (319) to 657(249) dyn*s*m-5 (p = 0.02). Quality of life considerably improved from a mean total score of 48(14) to 35(17) (p = 0.003) with improvements in the physical (from 25(5) to 17(7)) and emotional (from 11(6) to 6(5)) subscores (p = 0.005 and 0.011), respectively. The 6MWD improved from 389(78) to 443(79) meters (p = 0.005). 4 patients (27%) improved and 11 patients (73%) maintained their WHO class with no deterioration during the six months of bosentan treatment (p = 0.02). Uric acid serum levels declined from 525(145) to 453(151) micromol/l (p = 0.006), NTproBNP and CRPs declined insignificantly. Endothelin serum levels increased from 4.3(1.5) to 5.9(2.2) pg/ml (p = 0.025). Patients tolerated the treatment well, and there were no severe adverse events or deaths.
this open-label study suggests a beneficial effect of bosentan therapy not only on pulmonary haemodynamics, but also on quality of life and exercise capacity for patients with severe CTEPH
Symmetrized mean-field description of magnetic instabilities in k-(BEDT-TTF)_2Cu[N(CN)]_2 Y salts
We present a novel and convenient mean-field method, and apply it to study
the metallic/antiferromagnetic interface of k-(BEDT-TTF)_2Cu[N(CN)]_2 Y organic
superconductors (BEDT_TTF is bis-ethylen-dithio-tetrathiafulvalene, Y=Cl, Br).
The method, which fully exploits the crystal symmetry, allows one to obtain the
mean-field solution of the 2D Hubbard model for very large lattices, up to
6x10^5 sites, yielding a reliable description of the phase boundary in a wide
region of the parameter space. The metal/antiferromagnet transtion appears to
be second order, except for a narrow region of the parameter space, where the
transition is very sharp and possibly first order. The cohexistence of metallic
and antiferromagnetic properties is only observed for the transient state in
the case of smooth second order transitions. The relevance of the present
resaults to the complex experimental behavior of centrosymmetric k-phase
BEDT-TTF salts is discussed.Comment: 9 pages in PS format, 7 figures (included in PS), 1 tabl
Evidence for structural and electronic instabilities at intermediate temperatures in -(BEDT-TTF)X for X=Cu[N(CN)]Cl, Cu[N(CN)]Br and Cu(NCS): Implications for the phase diagram of these quasi-2D organic superconductors
We present high-resolution measurements of the coefficient of thermal
expansion of the quasi-twodimensional
(quasi-2D) salts -(BEDT-TTF)X with X = Cu(NCS), Cu[N(CN)]Br
and Cu[N(CN)]Cl. At intermediate temperatures (B), distinct anomalies
reminiscent of second-order phase transitions have been found at
K and 45 K for the superconducting X = Cu(NCS) and Cu[N(CN)]Br salts,
respectively. Most interestingly, we find that the signs of the uniaxial
pressure coefficients of are strictly anticorrelated with those of
. We propose that marks the transition to a spin-density-wave
(SDW) state forming on minor, quasi-1D parts of the Fermi surface. Our results
are compatible with two competing order parameters that form on disjunct
portions of the Fermi surface. At elevated temperatures (C), all compounds show
anomalies that can be identified with a kinetic, glass-like
transition where, below a characteristic temperature , disorder in the
orientational degrees of freedom of the terminal ethylene groups becomes frozen
in. We argue that the degree of disorder increases on going from the X =
Cu(NCS) to Cu[N(CN)]Br and the Cu[N(CN)]Cl salt. Our results
provide a natural explanation for the unusual time- and cooling-rate
dependencies of the ground-state properties in the hydrogenated and deuterated
Cu[N(CN)]Br salts reported in the literature.Comment: 22 pages, 7 figure
Disorder Effect on the Vortex Pinning by the Cooling Process Control in the Organic Superconductor -(BEDT-TTF)Cu[N(CN)]Br
We investigate the influence of disorders in terminal ethylene groups of
BEDT-TTF molecules (ethylene-disorders) on the vortex pinning of the organic
superconductor -(BEDT-TTF)Cu[N(CN)]Br. Magnetization
measurements are performed under different cooling-processes. The second peak
in the magnetization hysteresis curve is observed for all samples studied, and
the hysteresis width of the magnetization becomes narrower by cooling faster.
In contradiction to the simple pinning effect of disorder, this result shows
the suppression of the vortex pinning force by introducing more
ethylene-disorders. The ethylene-disorder domain model is proposed for
explaining the observed result. In the case of the system containing a moderate
number of the ethylene-disorders, the disordered molecules form a domain
structure and it works as an effective pinning site. On the contrary, an excess
number of the ethylene-disorders may weaken the effect of the domain structure,
which results in the less effective pinning force on the vortices.Comment: 6 pages, 6 figure
Thermal activation between Landau levels in the organic superconductor -(BEDT-TTF)SFCHCFSO
We show that Shubnikov-de Haas oscillations in the interlayer resistivity of
the organic superconductor -(BEDT-TTF)SF
CHCFSO become very pronounced in magnetic fields ~60~T.
The conductivity minima exhibit thermally-activated behaviour that can be
explained simply by the presence of a Landau gap, with the
quasi-one-dimensional Fermi surface sheets contributing negligibly to the
conductivity. This observation, together with complete suppression of chemical
potential oscillations, is consistent with an incommensurate nesting
instability of the quasi-one-dimensional sheets.Comment: 6 pages, 4 figure
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