The effects of parasitism and body length on positioning within wild fish shoals

The influence of body length and parasitism on the positioning behaviour of individuals in wild fish shoals was investigated by a novel means of capturing entire shoals of the banded killifish (Fundulus diaphanus, Lesueur) using a grid-net that maintained the two-dimensional positions of individuals within shoals. Fish in the front section of a shoal were larger than those in the rear. Individuals parasitized by the digenean trematode (Crassiphiala bulboglossa, Haitsma) showed a tendency to occupy the front of shoals. Parasitized fish were also found more in peripheral positions than central ones in a significant number of shoals. Shoal geometry was affected by the overall parasite prevalence of shoal members; shoals with high parasite prevalence displayed increasingly phallanx-like shoal formations, whereas shoals with low prevalence were more elliptical. There was no relationship between body length and parasite abundance or prevalence in the fish population which suggests body length and parasite status are independent predictors of positioning behaviour. Solitary individuals found outside shoals were both more likely to be parasitized and had higher parasite abundance than individuals engaged in shoaling. Differences in the shoaling behaviour of parasitized and unparasitized fish are discussed in the context of the adaptive manipulation hypothesis

Anatomy of relativistic pion loop corrections to the electromagnetic nucleon coupling

We present a relativistic formulation of pion loop corrections to the coupling of photons with nucleons on the light front. Vertex and wave function renormalization constants are computed to lowest order in the pion field, including their nonanalytic behavior in the chiral limit, and studied numerically as a function of the ultraviolet cutoff. Particular care is taken to explicitly verify gauge invariance and Ward-Takahashi identity constraints to all orders in the mπ expansion. The results are used to compute the chiral corrections to matrix elements of local operators, related to moments of deep-inelastic structure functions. Finally, comparison of results for pseudovector and pseudoscalar coupling allows the resolution of a longstanding puzzle in the computation of pion cloud corrections to structure function moments.Chueng-Ryong Ji, W. Melnitchouk, and A.W. Thoma

The Enamel Ultrastructure of Multituberculate Mammals: A Review

The enamel ultrastructure of multituberculate mammals has been sampled extensively and studied intensively and is better known than for any other group of early mammals. The enamel of the earliest multituberculates, those of the Late Triassic-Early Jurassic suborder Haramiyoidea and the Late Jurassic-early Early Cretaceous suborder Plagiaulacoidea, is preprismatic. With only two exceptions, all Late Cretaceous and early Tertiary genera of multituberculates examined have prismatic enamel. Prisms are either small with circular (complete) boundaries or large with arc-shaped (incomplete) boundaries. There is a remarkably consistent relationship between enamel ultrastructural type and subordinal taxa in that small, circular prisms are usually found within the suborder Ptilodontoidea and large, arc-shaped prisms are usually found in the suborder Taeniolabidoidea and in six Late Cretaceous-Early Tertiary genera of indeterminate subordinal status. Research currently in progress suggests that both small, circular prisms and large, arc-shaped prisms are homologous in all multituberculates in which they occur, with one exception. Neoliotomus, a taeniolabidoid, appears to have evolved small, circular prisms independently. In addition, it appears that large, arc-shaped prisms represent the primitive condition in multituberculates with prismatic enamel, not small, circular prisms as has been proposed previously

Measurement of the Casimir force between dissimilar metals

The first precise measurement of the Casimir force between dissimilar metals is reported. The attractive force, between a Cu layer evaporated on a microelectromechanical torsional oscillator, and an Au layer deposited on an Al$_2$O$_3$ sphere, was measured dynamically with a noise level of 6 fN/$\sqrt{\rm{Hz}}$. Measurements were performed for separations in the 0.2-2 $\mu$m range. The results agree to better than 1% in the 0.2-0.5 $\mu$m range with a theoretical model that takes into account the finite conductivity and roughness of the two metals. The observed discrepancies, which are much larger than the experimental precision, can be attributed to a lack of a complete characterization of the optical properties of the specific samples used in the experiment.Comment: 6 pages, 4 figure

Pregnancy-associated breast cancer - Special features in diagnosis and treatment

For obvious psychological reasons it is difficult to associate pregnancy - a life-giving period of our existence with life-threatening malignancies. Symptoms pointing to malignancy are often ignored by both patients and physicians, and this, together with the greater difficulty of diagnostic imaging, probably results in the proven delay in the detection of breast cancers during pregnancy. The diagnosis and treatment of breast cancer are becoming more and more important, as the fulfillment of the desire to have children is increasingly postponed until a later age associated with a higher risk of carcinoma, and improved cure rates of solid tumors no longer exclude subsequent pregnancies. The following article summarizes the special features of the diagnosis and primary therapy of pregnancy-associated breast cancer with particular consideration of cytostatic therapy

Problems with kinematic mean field electrodynamics at high magnetic Reynolds numbers

We discuss the applicability of the kinematic $\alpha$-effect formalism at high magnetic Reynolds numbers. In this regime the underlying flow is likely to be a small-scale dynamo, leading to the exponential growth of fluctuations. Difficulties arise with both the actual calculation of the $\alpha$ coefficients and with its interpretation. We argue that although the former may be circumvented -- and we outline several procedures by which the the $\alpha$ coefficients can be computed in principle -- the interpretation of these quantities in terms of the evolution of the large-scale field may be fundamentally flawed.Comment: 5 pages, LaTeX, no figure

LAPS and SPIM Imaging Using ITO-Coated Glass as the Substrate Material

Light-addressable potentiometric sensors (LAPS) and scanning photo-induced impedance microscopy (SPIM) use photocurrent measurements for spatiotemporal imaging of ion concentrations, electrical potentials, and impedance. In this work, ITO-coated glass was confirmed to produce photocurrents at anodic potentials with 405 nm diode laser illumination. Therefore, it was developed as a low cost and robust substrate material for LAPS and SPIM imaging compared to traditional expensive ultrathin Si substrates. ITO showed good ac photocurrent and pH response without surface modification and insulator. Local photocurrents were produced by scanning a focused laser beam across the sample, which proved the light addressability of ITO-coated glass. With a high-impedance PMMA dot deposited onto the ITO as a model system, a lateral resolution of about 2.3 μm was achieved

Wind measurement system

A system for remotely measuring vertical and horizontal winds present in discrete volumes of air at selected locations above the ground is described. A laser beam is optically focused in range by a telescope, and the output beam is conically scanned at an angle about a vertical axis. The backscatter, or reflected light, from the ambient particulates in a volume of air, the focal volume, is detected for shifts in wavelength, and from these, horizontal and vertical wind components are computed

Topography and lithology of the Mendocino Ridge

Twenty-two slope-corrected bathymetric profiles of the Mendocino Ridge between 125°W and 129°W are presented, and the method of their development is discussed. The crest of this Ridge lies at an average depth of 2000 m, falling off to 3200 m on the north and to 4400 m on the south. A short, steep scarp, fresh dredge-haul material lacking manganiferous crusts, and earthquake epicenters suggest recent faulting on the north...