Unusual surface states associated with the PT-symmetry breaking and antiferromagnetic band folding in NdSb

We have performed micro-focused angle-resolved photoemission spectroscopy on NdSb which exhibits the type-I antiferromagnetism below TN = 16 K. We succeeded in selectively observing the band structure for all the three types of single-q antiferromagnetic (AF) domains at the surface. We found that the two of three surfaces whose AF-ordering vector lies within the surface plane commonly show two-fold-symmetric surface states (SSs) around the bulk-band edges, whereas the other surface with an out-of-plane AF-ordering vector displays four-fold-symmetric shallow electronlike SS at the Brillouin-zone center. We suggest that these SSs commonly originate from the combination of the PT (space-inversion and time-reversal) symmetry breaking at the surface and the band folding due to the AF order. The present results pave a pathway toward understanding the relationship between the symmetry and the surface electronic states in antiferromagnets.Comment: 20 pages, 5 figure

INITIAL LESIONS IN CHICKENS INFECTED WITH JM STRAIN OF MAREK'S DISEASE VIRUS

Severe lymphoid degeneration and hyperplasia of the reticular and epithelial components were present in the lymphoid tissues on the 6〜8th day after inoculation of JM strain of Marek's disease virus (MDV). At the same time, intranuclear and cytoplasmic inclusions with many virus particles were frequently found in these components of the lymphoid tissues (the bursa of Fabricius and thymus). Inaclusions were also observed in the epithelial cells of the pancreas, adrenal glands, kidneys and feather follicles. Two types of enveloped virus particles were found in adrenal cells and the feather follicle epithelium (FFE). Inoculated chickens were free from precipitating antibodies to MDV through a 48 day observation period. Immunofluorescent (IF) antigen was first detected in the thymus and lungs (8th day). MDV was demonstrated to exist by kidney cell cultures from the 8th day postinoculation. Microscopic lesions characteristic for MD were seen on and after the 12th day postinoculation. In contact-exposed chickens, there were no remarkable changes in the lymphoid tissues at the early stage of the disease. Thereafter inclusions could not be found in any tissues, except the skin and lungs. Precipitating antibodies to MDV were detected from the 60th day postexposure. IF antigen was detected in the thymus and FFE (23rd day). MDV was demonstrated to exist and microscopic lesions were seen on and after the 32nd day postexposure

A Fundamental Study on Influence of Concurrently Presented Visual Stimulus Upon Loudness Perception

As a basic study on the influence of the dynamic properties of the audio-visual stimuli upon interaction between audition and vision, the effect of the simple movement involved in the visual stimulus on the loudness perception of the audio stimulus was investigated via psychophysical experiment. In this experiment, the visual stimulus given to subjects along with the audio stimulus is a bar appeared on a display, one side of which is flexibly expanding and contracting. The loudness of the audio stimulus with such a visual effect concurrently presented was rated as an absolute numerical value by using the Magnitude Estimation method. The reference of the bar length is determined so as to correspond to the Zwicker's loudness calculated for the given audio stimulus. As a result, the visual stimulus did not affect the loudness perception, when the bar was presented with its length same as the reference. On the other hand, the rating of the loudness for the same audio stimulus was significantly increased when the bar length was longer than the reference. This indicates that the change in the correspondence between the audio and the visual stimuli affect the loudness perception