Enhanced infrared magneto-optical response of the nonmagnetic semiconductor BiTeI driven by bulk Rashba splitting.

We study the magneto-optical (MO) response of the polar semiconductor BiTeI with giant bulk Rashba spin splitting at various carrier densities. Despite being nonmagnetic, the material is found to yield a huge MO activity in the infrared region under moderate magnetic fields (up to 3 T). Our first-principles calculations show that the enhanced MO response of BiTeI comes mainly from the intraband transitions between the Rashba-split bulk conduction bands. These transitions connecting electronic states with opposite spin directions become active due to the presence of strong spin-orbit interaction and give rise to distinct features in the MO spectra with a systematic doping dependence. We predict an even more pronounced enhancement in the low-energy MO response and dc Hall effect near the crossing (Dirac) point of the conduction bands.

Mechanisms of enhanced orbital dia- and paramagnetism: application to the Rashba semiconductor BiTeI.

We study the magnetic susceptibility of a layered semiconductor BiTeI with giant Rashba spin splitting both theoretically and experimentally to explore its orbital magnetism. Apart from the core contributions, a large temperature-dependent diamagnetic susceptibility is observed when the Fermi energy E(F) is near the crossing point of the Rashba spin-split conduction bands at the time-reversal symmetry point A. On the other hand, when E(F) is below this band crossing, the susceptibility turns to be paramagnetic. These features are consistent with first-principles calculations, which also predict an enhanced orbital magnetic susceptibility with both positive and negative signs as a function of E(F) due to band (anti)crossings. Based on these observations, we propose two mechanisms for the enhanced paramagnetic orbital susceptibility.

Optical response of relativistic electrons in the polar BiTeI semiconductor.

The transitions between the spin-split bands by spin-orbit interaction are relevant to many novel phenomena such as the resonant dynamical magnetoelectric effect and the spin Hall effect. We perform optical spectroscopy measurements combined with first-principles calculations to study these transitions in the recently discovered giant bulk Rashba spin-splitting system BiTeI. Several novel features are observed in the optical spectra of the material including a sharp edge singularity due to the reduced dimensionality of the joint density of states and a systematic doping dependence of the intraband transitions between the Rashba-split branches. These confirm the bulk nature of the Rashba-type splitting in BiTeI and manifest the relativistic nature of the electron dynamics in a solid.

Fulminant septic melioidosis after a vacation in Thailand.

Severe infection with Burkholderia pseudomallei (formerly Pseudomonas pseudomallei), the bacterium causing melioidosis, is a common cause of acquired septicaemia in south-east Asia and northern Australia. A few cases of infected travellers returning to European countries have been reported. Melioidosis is a tropical disease, the clinical presentation ranging from asymptomatic infection to fulminant sepsis. Predisposing conditions such as impaired cellular immunity, preexisting renal failure or diabetes mellitus seem to enhance the severity of the disease. For a definite diagnosis the bacterium has to be isolated. The antimicrobial treatment of choice is ceftazidime in combination with co-trimoxazole or doxycycline. Even with correct antibiotic treatment the mortality rate is high in cases of fulminant sepsis. We report a 29-year old man with Type I diabetes who acquired melioidosis during a vacation in Thailand. After returning to Austria he was admitted to the intensive care unit with multiple organ failure. Despite intensive care treatment the patient's infection proved lethal. Burkholderia pseudomallei was isolated from the blood and bronchoalveolar lavage.

Mould-devouring mites differ in guanine excretion from dust-eating Acari, a possible error source in mite allergen exposure studies.

BACKGROUND AND OBJECTIVE: Measurement of guanine in dust proved a good assessment of mite allergen exposure. METHODS: Exposure to mite allergens may lead to atopic inflictions. In a semi-natural test system the development of Dermatophagoides pteronyssinus (Trouessart) and Glycyphagus domesticus (De Geer), and the presence of their guanine excretion, was examined in a dust-soiled and mouldy environment. Mites were counted after heat-escape, and guanine was detected by means of capillary zone electrophoresis. For each species, 50 mites randomly taken, were inoculated on soiled test-surfaces of 10 x 10 cm. Rough wooden board, gypsum board, tufted carpet, and a self-made mattress representing wall surfaces and home-textiles, respectively, were used. Eight weeks after inoculation with mites only, the surfaces were all mould ridden, and mite and guanine measurements were taken. The Spearman rank correlation test and the Mann-Whitney U-test were used in statistical analysis. The confidence limit was set at 1%. RESULTS: Among the various test-surfaces, no differences were found regarding total mite numbers and amount of guanine present (P > 0.01). For the dust-eating mite D. pteronyssinus, total mite numbers correlated with the amount of guanine present (P = 0.002) on all inoculated surfaces, indicating feeding on the protein-rich dust. For the mould devouring mite G. domesticus, however, no such correlation was found (P = 0.72). Apparently, they mainly consumed fungal carbohydrates during this experiment. CONCLUSION: The allergological relevance of storage mites has been under discussion for the last 25 years. In humid homes, these mites will feed almost exclusively on fungi and may produce allergenic or irritating substances different from those arising on protein-rich laboratory media used in allergen extract production or present in carpets, bedding and furniture.

[Acute hepatitis as the leading symptom of secondary syphilis]. / Akute Hepatitis als Leitsymptom einer Sekundärlues.

HISTORY AND CLINICAL FINDINGS: A 44-year-old heterosexual man reported having been jaundiced for 4 days. He drank little alcohol. There was no history of venereal disease. INVESTIGATIONS: Laboratory tests indicated marked cholestasis (alkaline phosphatase 1589 U/I, gamma-GT 449 U/I), but only moderately raised transaminases (GOT 66 U/I, GPT 230 U/I), with a bilirubin level of 4.8 mg/dl. Ultrasonography revealed diffuse parenchymal damage in the liver, while endoscopic retrograde cholangiopancreatography showed no abnormalities. Viral hepatitis was excluded by serological tests. Histology of a liver biopsy showed inflammatory infiltration of the portal areas and of the liver parenchyma. Routine syphilis serology indicated fresh infection with Treponema pallidum. There was a healing painless ulcer in the area of the sulcus coronarius of the genitals. TREATMENT AND COURSE: 2.4 mill. I.U. benzathine benzylpenicillin were administered intramuscularly. This rapidly improved his condition and liver function tests became normal. CONCLUSION: In case of hepatitis of uncertain genesis syphilis should be considered as a possible cause, even in the absence of other signs of the disease.

[Complicated aneurysm of the splenic artery]. / Das komplizierte Lienalis-Aneurysma.

For 2 1/2 years after sustaining blunt trauma to the abdomen a 51-year-old woman had experienced episodes of pain, recently with throbbing, in the left upper quadrant. A smooth, circumscribed, painless tumour filling the left upper and mid-abdomen was palpable under the left costal margin. Ultrasound revealed a 12 x 11 cm space-occupying mass with cystic-fluid components, at first interpreted as a blood-containing pseudocyst. Computed tomography demonstrated a connection with the splenic artery. Digital subtraction angiography established the diagnosis of an aneurysm of the splenic artery arising immediately beyond its origin from the coeliac trunk. Splenectomy and resection of the aneurysm were performed. Total removal of the aneurysm was not undertaken because the dorsal aspect of the aneurysm wall was very thick and fused with the retroperitoneum. The postoperative course was unremarkable. The genesis of splenic aneurysm often remains unexplained. Its occurrence after blunt abdominal trauma is exceedingly rare.

Comparative efficacy of house dust mite extermination products.

The acaricidal efficacy of nine marketed products, i.e. Acardust, Acarosan (foam and powder), Actelic 50, Artilin 3A (spirit and water base), liquid nitrogen, Paragerm AK, and Tymasil, and of intensive vacuum-cleaning have been compared on four different test surfaces: mattress, tufted carpet, gypsum board and rough wooden board, all covered with artificial house dust. They were inoculated with the house dust mite, Dermatophagoides pteronyssinus or the house-dust fungus Aspergillus repens for evaluation of the fungistatic claims of some products. The acaricidal activity of Tymasil did not surpass that of vacuuming; its fungistatic effect was not apparent. The other products showed complete to almost complete eradication on at least one of the substrates tested. Taking into account the results of acaricidal efficacy as well as the data on safety and practicality acquired earlier, Acarosan powder was considered first choice for carpet treatment. Acarosan and liquid nitrogen, were found to be effective in the treatment of mattress, pillow, upholstered furniture and heavy curtains. On wooden surfaces Acarosan was found to be both effective and safe, while Acardust, Actelic 50, Artilin 3A (both fungistatic as well as acaricidal), liquid nitrogen and Paragerm also passed the efficiency test.

Fungi in carpeting and furniture dust.

The qualitative and quantitative species composition of fungi in carpets and upholstered furniture dust found in the living-rooms of nine Dutch dwellings was examined in a pilot study. Numbers of spores of xerophilic fungi did not differ in dust removed from carpeting and upholstery. Spores of hydrophilic species were found to be more predominant on floors (P less than 0.05), whereas meso-hygrophilic spores, largely dominated by allergologically relevant Penicillium species, were significantly more abundant in dust taken from regularly used furniture (P less than 0.05). Our results indicate that growth conditions for fungi in the micro-habitats of furniture differ from those in carpeting. No statistically significant differences in number of viable spores have been found in samples taken from ground-floor level compared with those taken from 1st to 3rd floor level of dwellings. From this study, the need for a micro-topographic analysis of the fungal flora in the human environment has become apparent. Efficient allergological home sanitation in dwellings of allergic patients requires detailed data about the colonization of the various micro-habitats by allergenic fungi.

The management of house dust mite allergies.

A safe and practical home sanitation procedure for the removal of house dust mites (Dermatophagoides pteronyssinus) and their allergens is described. The severity of mite infestation was assessed with the use of the Acarex test, which measures the concentration of guanine in house dust, and all affected house textiles were then treated with an Acarosan product. The active ingredient of Acarosan is benzyl benzoate, which has been used as a scabicide for over 100 years. The results of several studies of Acarosan treatment were reviewed and it was concluded that use of the guanine test and Acarosan products allows many sensitized persons to control the concentration of house dust mite allergens in their homes.

Control of house-dust mites (Pyroglyphidae) with home disinfectants.

Chemical disinfectants and biocidal preparations used in households were tested in the laboratory for their ability to kill the house-dust mite Dermatophagoides farinae. Batches of ten specimens were soaked in aqueous solutions or suspensions containing 0.0, 0.1, 0.3, 1.0, 3.0 and 10.0% (by volume) of the test preparations. Direct effect was tested without food. Population effect was tested with food added. The results showed a high mortality with all preparations except for a regular carpet cleaner (containing detergents) and natamycin (a fungicide). Nevertheless, not all tested preparations are practical in the home environment. Best results in homes were obtained with a carpet cleaning solution which incorporates an acaricide (benzylbenzoate). This particular preparation has an outstanding acaricidal efficacy and can easily and routinely be used by the householder. The degree of cleanliness in the household is a measure of the number of house-dust mites and their allergens.