Is the `Finite Bias Anomaly' in planar GaAs-Superconductor junctons caused by point-contact like structures?

We correlate transmission electron microscope (TEM) pictures of superconducting In contacts to an AlGaAs/GaAs heterojunction with differential conductance spectroscopy performed on the same heterojunction. Metals deposited onto a (100) AlGaAs/GaAs heterostructure do not form planar contacts but, during thermal annealing, grow down into the heterostructure along crystallographic planes in pyramid-like `point contacts'. Random surface nucleation and growth gives rise to a different interface transmission for each superconducting point contact. Samples annealed for different times, and therefore having different contact geometry, show variations in $dI/dV$ characteristic of ballistic transport of Cooper pairs, wave interference between different point emitters, and different types of weak localization corrections to Giaever tunneling. We give a possible mechanism whereby the `finite bias anomaly' of Poirier et al. (Phys. Rev. Lett., {\bf 79}, 2105 (1997)), also observed in these samples, can arise by adding the conductance of independent superconducting point emitters in parallel

Seasonal and diurnal variation in the calls of the noisy Pitta Pitta versicolor, Eastern whipbird psophodes olivaceus and green catbird Ailuroedus crassirostris in Brisbane Forest Park, Queensland

Noisy Pittas and Green Catbirds showed a marked increase in calling associated with the breeding season and then declined to much lower levels in winter. Eastern Whipbirds had a peak of calling at the start of the breeding season but then maintained a relatively high level throughout the year. All three species had a peak of calling around sunrise which then declined during the day with a slight increase around noon and a greater increase at sunset. In Noisy Pittas, the secondary peaks at noon and sunset were much larger than in the other two species. Noisy Pittas, a suboscine in the suborder Tyranni, had a similar temporal pattern of calling to that found in oscines

The structure and some functional aspects of the eggshell of the broad shelled river tortoise chelodina expansa ( Testudinata: Chelidae)

C. expansa eggs have a brittle calcareous shell composed of needle-like aragonite crystals which radiate from a central core to form conical shell units. The shell is attached to a multi-layered fibrous shell- membrane, the layers of which separate to form an air space at one end of the egg. Funnel-shaped pores occur at the junctions of some shell units. The shell is similar in thickness to that of comparable birds' eggs but the shell membrane is three times thicker. Pores are less dense at the poles of the egg than at equatorial regions but even here they are much less dense than in birds' eggs. Pore diameter is larger than in birds'eggs but this is largely due to the funnel-shape of the pores. Water vapour conductance is six times higher in C. expansa eggs than in comparable birds' eggs. This increase cannot be explained by a larger pore area but may result from water vapour conductance through cracks in the shell, which are frequently observed. The thicker shell-membrane may compensate for these cracks and the partial loss of the shell

Nest height of the red bishop (Eupiectes orix)

Heights of nests and reeds in a colony of red bishops (Euplectes orix) in Phragmites mauritianus reeds on the Makabusi River, Zimbabwe were measured in two breeding seasons. Nests were placed high in the reeds with fewer above the mean and more below the mean than in a normal distribution. During the course of a breeding season, nest height increased in response to increasing reed height and the nest height/reed height percentage was relatively constant at 70%. Nest height had a higher correlation and regression coefficient with reed height in lower reeds than in reeds over 280 cm tall. Most nests were placed in reeds with diameters of 10-12 mm. Higher positions, where the diameters of the reeds were smaller than this, the reeds were weaker probably because of a lack of llgnificatlon. In one breeding season, nests used by females were significantly lower than nest frames left unused but breeding success appeared unaffected by variation in nest height. Nesting high in the reeds might be a response to ground predators and climatic factors, particularly the requirement for nest ventilation to remove excess water vapour

Waterbird populations in the brisbane region, 1972-83, and correlates with rainfall and water heights

Mean numbers and annual variation of 52 species of waterbirds (families Podicipedidae; Pelicanidae; Anhingidae; Phalacrocoracidae; Ardeidae; Ciconiidae; Plataleidae; Anatidae; Rallidae; Jacanidae) from the Queensland Ornithological Society’s records of the Brisbane region during 1972-83 are presented. Changes in the numbers of many species showed significant negative correlations with changes in the Moreton winter rainfall (3 months before the count). Changes in numbers of hardheads, grey teal and Eurasian coot also had significant negative correlations with changes of inland rainfall, and many other species showed similar trends. Changes in numbers of darter and pied cormorant were positively correlated with changes in Moreton and Warrego rainfall respectively. Most species had non-significant correlations with Moreton dam levels, but for chestnut teal, white-faced heron and dusky moorhen these approached statistical significance (P < 0-1). Numbers of whitefaced heron, black swan, comb-crested jacana and darter decreased, and those of Australian pelican and plumed and wandering whistling-ducks increased during the survey period. The coastal and inland distribution of some species is also presented

The male reproductive system and the phylogeny of elephant‐shrews (Macroscelidea)

Elephant‐shrews show many unusual features of their reproductive systems. The testes lie in the abdominal cavity, just caudal to the kidneys, and are relatively very small. The epididymis is long and most sperm are stored in a coiled region, possibly homologous to the cauda epididymidis, adjacent to the rectum. Spermatogenesis occurs throughout the year but there are marked seasonal changes in the size of the testis and accessory glands. The spermatozoa have a spatulate‐shaped nucleus with a long acrosome. The subacrosome is pointed or more rounded in Macroscelides and Petrodromus but is anvil‐shaped in Elephantulus with lateral barbs. Coarse fibres 1,5,6 and 9 are enlarged but in E. edwardii there is a great enlargement of all the coarse fibres. The accessory glands consist of five pairs of prostate glands, a uterus masculinus and a pair of bulbourethral glands. The penis is very long and runs cranially under the abdominal skin. The distal end of the glans has a characteristic shape for each genus. Features of the male reproductive system give no support for the suggested relationship of elephant‐shrews with lagomorphs and rodents but do show some similarities with the paenungulates (hyrax, elephant and sireneans). Copyrigh

Breeding season and clutch size of the noisy pitta pitta versicolor in tropical and subtropical australia

Data on the breeding season and clutch size of the Noisy Pitta Pitta versicolor were obtained from the liter­ature, RAOU’s Nest Record Scheme and egg collections in Australia and overseas. Overall most egg laying occurs be­tween October and January but on Cape York Peninsula it is significantly later (November-February). This is likely to be associated with the very seasonal rainfall on Cape York compared with other regions. Clutches of three and four were most common. That clutches were significantly small­er in tropical than subtropical regions may be associated with the scarcity of food resources in humid tropical rain forest

On mammalian sperm dimensions

Data on linear sperm dimensions in mammals are presented. There is information on a total of 284 species, representing 6.2% of all species; 17.2% of all genera and 49.2% of all families have some representation, with quantitative information missing only from the orders Dermoptera, Pholidota, Sirenia and Tubulidentata. In general, sperm size is inverse to body mass (except for the Chiroptera), so that the smallest known spermatozoa are amongst those of artiodactyls and the largest are amongst those of marsupials. Most variations are due to differences in the lengths of midpiece and principal piece, with head lengths relatively uniform throughout the mammals

Ultrastructure of spermatozoa of the yellow-rumped elephant shrew Rhynchocyon chrysopygus (Mammalian: Macroscelidea) and the phylogeny of elephant shrews

The spermatozoa of the yellow‐rumped elephant shrew Rhynchocyon chrysopygus have a spatulate head, tapering to a rounded proximal end with a marked narrowing at the equatorial segment. There is a short pointed subacrosome and about 24 gyres of mitochondria were found in the midpiece. The coarse fibres surrounding the axonome show enlargement of numbers 1, 5, 6 and 9. The spermatozoa of all genera of elephant shrews have now been described allowing comparisons among them. R. chrysopygus has the shortest spermatozoon and the fewest number of gyres. The pointed subacrosome is considered an ancestral feature and is shared with Macroscelides. The enlargement of coarse fibres 1, 5, 6 and 9 is found in several groups including members of the archonta and paenungulates, both postulated as being related to elephant shrews. 1995 The Royal Swedish Academy of Science