Magnon Heat Conductivity and Mean Free Paths in Two-Leg Spin Ladders: A Model-Independent Determination

The magnon thermal conductivity $\kappa_{\mathrm{mag}}$ of the spin ladders in $\rm Sr_{14}Cu_{24-x}Zn_xO_{41}$ has been investigated at low doping levels $x=0$, 0.125, 0.25, 0.5 and 0.75. The Zn-impurities generate nonmagnetic defects which define an upper limit for $l_{\mathrm{mag}}$ and therefore allow a clear-cut relation between $l_{\mathrm{mag}}$ and $\kappa_{\mathrm{mag}}$ to be established independently of any model. Over a large temperature range we observe a progressive suppression of $\kappa_{\mathrm{mag}}$ with increasing Zn-content and find in particular that with respect to pure $\rm Sr_{14}Cu_{24}O_{41}$ $\kappa_{\mathrm{mag}}$ is strongly suppressed even in the case of tiny impurity densities where $l_{\mathrm{mag}}\lesssim 374$~{\AA}. This shows unambiguously that large $l_{\mathrm{mag}}\approx 3000$~{\AA} which have been reported for $\rm Sr_{14}Cu_{24}O_{41}$ and $\rm La_{5}Ca_9Cu_{24}O_{41}$ on basis of a kinetic model are in the correct order of magnitude

Star-shaped Local Density of States around Vortices in a Type II Superconductor

The electronic structure of vortices in a type II superconductor is analyzed within the quasi-classical Eilenberger framework. The possible origin of a sixfold ``star'' shape of the local density of states, observed by scanning tunneling microscope experiments on NbSe$_2$, is examined in the light of the three effects; the anisotropic pairing, the vortex lattice, and the anisotropic density of states at the Fermi surface. Outstanding features of split parallel rays of this star are well explained in terms of an anisotropic $s$-wave pairing. This reveals a rich internal electronic structure associated with a vortex core.Comment: 4 pages, REVTeX, 3 figures available upon reques

Long-Term Administration of Calcium Acetate Efficiently Controls Severe Hyperphosphataemia in Haemodialysis Patients

In order to avoid aluminium toxicity, calciumcontaining phosphate binders have been used increasingly. Unfortunately, calcium carbonate and calcium citrate produce hypercalcaemia in a number of patients. New studies have shown that calcium acetate is promising in that it binds more phosphate than calcium carbonate at comparable doses. We tested calcium acetate in eight severely hyperphosphataemic patients (2.25 ± 0.08 mmol/l) on maintenance haemodialysis over 5 months. Serum phosphate decreased to 1.86 ± 0.06 mmol/l, but at the cost of an increase in serum calcium. However, the increment of serum calcium was always less than the respective decrease of serum phosphate, and hypercalcaemia—immediately reversible after dose reduction—only occurred once in two patient

Local density of states in the vortex lattice in a type II superconductor

Local density of states (LDOS) in the triangular vortex lattice is investigated based on the quasi-classical Eilenberger theory. We consider the case of an isotropic s-wave superconductor with the material parameter appropriate to NbSe_2. At a weak magnetic field, the spatial variation of the LDOS shows cylindrical structure around a vortex core. On the other hand, at a high field where the core regions substantially overlap each other, the LDOS is sixfold star-shaped structure due to the vortex lattice effect. The orientation of the star coincides with the experimental data of the scanning tunneling microscopy. That is, the ray of the star extends toward the nearest-neighbor (next nearest-neighbor) vortex direction at higher (lower) energy.Comment: 10 pages, RevTex, 32 figure

Quantal analysis of long-term potentiation of combined neuronal postsynaptic potentials on hippocampal slices in vitro.

10.1007/BF0105247

Magnon-Hole Scattering and Charge Order in Sr14−xCaxCu24O41Sr_{14-x}Ca_xCu_{24}O_{41}

The magnon thermal conductivity $\kappa_{\mathrm{mag}}$ of the hole doped spin ladders in $\rm Sr_{14-x}Ca_xCu_{24}O_{41}$ has been investigated at low doping levels $x$. The analysis of $\kappa_{\mathrm{mag}}$ reveals a strong doping and temperature dependence of the magnon mean free path $l_{\mathrm{mag}}$ which is a local probe for the interaction of magnons with the doped holes in the ladders. In particular, this novel approach to studying charge degrees of freedom via spin excitations shows that charge ordering of the holes in the ladders leads to a freezing out of magnon-hole scattering processes

You are What You Wear: Unless You Moved—Effects of Attire and Posture on Person Perception

While first impressions are often based on appearance cues, little is known about how these interact with information from other channels. The present research aimed to investigate the impact of occupational stereotypes, evoked by attire, as well as posture on person perception. For this, computer animation was used to create avatars with different types of attire (nurse, military, casual) and posture (open, closed). In Study 1 (N = 164), participants attributed significantly more empathy to avatars wearing a nurse versus a military uniform or casual outfit. When adding posture as an additional cue, Study 2 (N = 312) showed that ratings of empathy and dominance were affected by both attire and posture. This effect was replicated in Study 3 (N = 163) for female avatars, in the sense that open postures in nurses increased empathy ratings and decreased dominance ratings, which both in turn led to greater perceived competence. By contrast, for male avatars, posture did not affect attributions of competence directly. Rather, attire predicted perceived dominance directly, as well as through perceived empathy. The present findings suggest that both posture, and occupational information evoked by attire, are used to infer personal characteristics. However, the strength of each cue may vary with the gender of the target