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If a current of electrons flows through a normal conductor (in contrast to a superconductor), it is impeded by local scattering at defects as well as phonon scattering. Both effects contribute to the voltage drop observed for a macroscopic complex system as described by Ohm's law. Although this concept is well established, it has not yet been measured around individual defects on the atomic scale. We have measured the voltage drop at a monatomic step in real space by restricting the current to a surface layer. For the Si(111)-( [see text]3 x [see text]3)-Ag surface a monotonous transition with a width below 1 nm was found. A numerical analysis of the data maps the current flow through the complex network and the interplay between defect-free terraces and monatomic steps.

Background The incidence and the scale of recovery of the taste function after middle ear surgery is usually determined by the use of anamnestic data and electrogustometry. Methods Taste tests (regional chemical taste test, electrogustometry and subjective evaluation) were performed preoperatively, 2 to 3 weeks and 6 to 9 months after middle ear surgery. These results were evaluated by taking the scale of chorda tympani nerve (CTN) manipulation into consideration. Three groups were chosen: group 1: no or small CTN manipulation, n = 54; group 2: strong CTN manipulation, n = 14; group 3: severed CTN, n = 50. Patients In a prospective study 118 patients were examined after middle ear surgery in the ENT-Department of the University of Rostock between 2001 and 2002. 61 females and 57 males, age from 7 - 81 years, were included. Results Complaints were observed in all three groups, mainly in groups 2 and 3. These included taste disorders, taste phenomenon and numbness of the tongue. Using regional chemical taste tests, the taste loss of group 3 could be proven for those patients with complaints in 64 % and for those patients without complaints in 27 %. The electrogustometry is more sensitive than chemical taste test. All patients had pathological thresholds after chorda cutting (78 % no thresholds; 22 % elevated thresholds). 68 out of 118 patients (58 %) had a second follow-up after 6 to 9 months after middle ear surgery. The complaints are declining in all groups. In groups 2 and 3 a recovery of taste function could be observed. Even if the number of patients with severed chorda, who suffer from taste disorders, diminishes, a recovery of the taste function could only be observed in 30 %. Conclusions The scale of chorda manipulation is important for the recovery of the taste function after middle ear surgery. The CTN should be preserved intraoperatively, especially when an operation of the contralateral ear is planned as well.

We present a combined cross-section scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) and ab initio simulations study of the nonpolar $(11\overline{2}0)$ cleaved surface of 6H-SiC. The experimental results show an unreconstructed surface in agreement with theory. Upon truncation, two surface bands appear inside the semiconductor band gap: one empty band localized on the Si atoms and one filled band on the C atoms. According to the STS experimental results on $n$-doped samples, the Fermi energy is pinned at the surface inside the band gap. By comparison of STM filled and empty states topographies we propose that on the fresh cleaved surface the Fermi level lies at the bottom of the Si-like band. The calculated STM images reproduce the experimental contrast of the 6H stacking sequence and its bias dependence very well.

The incidence and the scale of recovery of the taste function after middle ear surgery is usually determined by the use of anamnestic data and electrogustometry.Taste tests (regional chemical taste test, electrogustometry and subjective evaluation) were performed preoperatively, 2 to 3 weeks and 6 to 9 months after middle ear surgery. These results were evaluated by taking the scale of chorda tympani nerve (CTN) manipulation into consideration. Three groups were chosen: group 1: no or small CTN manipulation, n = 54; group 2: strong CTN manipulation, n = 14; group 3: severed CTN, n = 50.In a prospective study 118 patients were examined after middle ear surgery in the ENT-Department of the University of Rostock between 2001 and 2002. 61 females and 57 males, age from 7 - 81 years, were included.Complaints were observed in all three groups, mainly in groups 2 and 3. These included taste disorders, taste phenomenon and numbness of the tongue. Using regional chemical taste tests, the taste loss of group 3 could be proven for those patients with complaints in 64 % and for those patients without complaints in 27 %. The electrogustometry is more sensitive than chemical taste test. All patients had pathological thresholds after chorda cutting (78 % no thresholds; 22 % elevated thresholds). 68 out of 118 patients (58 %) had a second follow-up after 6 to 9 months after middle ear surgery. The complaints are declining in all groups. In groups 2 and 3 a recovery of taste function could be observed. Even if the number of patients with severed chorda, who suffer from taste disorders, diminishes, a recovery of the taste function could only be observed in 30 %.The scale of chorda manipulation is important for the recovery of the taste function after middle ear surgery. The CTN should be preserved intraoperatively, especially when an operation of the contralateral ear is planned as well.

Fe films of up to 10 ML thickness were grown on cleaved GaAs(110) in a two-step process that associates low-temperature deposition at 130K with a subsequent annealing to room temperature. Low-energy electron diffraction, scanning tunneling microscopy, and in situ magneto-optical Kerr effect were combined to study these films. The observed magnetic and structural properties are distinctly different from the characteristics of conventionally grown Fe films on GaAs. We found no indication of interface compound formation. The applied two-step growth process is a promising technique to further increase spin-injection and detection efficiencies of Fe∕GaAs hybrid structures.