Number 15 (August 1984)

A Report on the Fishes of Bull Mountain Creek, with Comments on the Status of Rare Species. By M. Pierson and C.A. Schultz, 3 pp. Fishes of the Middle Fork of the Kentucky River, Kentucky. By B.A. Branson and D.L. Batch, 7 pp. A Survey of Fish Communities of Streams in Coal Surface Mining Areas of the Cumberland Plateau, Tennessee. By C.J. O\u27Bara and R.D. Estes, 4 pp. Recent Collections of Fishes from the Big South Fork of the Cumberland River System, Tennessee and Kentucky. By C.J. O\u27Bara and R.D. Estes, 5 pp

Run-and-tumble particles in speckle fields

The random energy landscapes developed by speckle fields can be used to confine and manipulate a large number of micro-particles with a single laser beam. By means of molecular dynamics simulations, we investigate the static and dynamic properties of an active suspension of swimming bacteria embedded into speckle patterns. Looking at the correlation of the density fluctuations and the equilibrium density profiles, we observe a crossover phenomenon when the forces exerted by the speckles are equal to the bacteria's propulsion

Partial substitution of concentrates by maize silage in rations for organic dairy cows and its influence on performance and utilization efficiency

The aim of the present study was to investigate the influence of partial substitution of purchased concentrates with maize silage on feed intake, energy and nutrient supply, milk production and feed utilization efficiency in organic dairy cows. In the experiment, two winter rations were compared. In the experimental group (E) 2/3 of average herd concentrate intake were replaced by maize silage. In group E total dry matter, protein und energy intake was significantly lower than in the control group (C) (16.3 and 17.8 kg, 99 and 110 MJ NEL, 2170 and 2460 g crude protein, respectively). Milk yield decreased in group E by 1.7 kg, which was not statistically significant. Ruminal nitrogen balance and dietary protein to energy ratio was significantly lower in group E as compared to group C (-8 and 22 g, 21 and 24 g/MJ NEL, respectively). The diet for group E had no effect on milk composition, except milk urea content, which was in tendency lower in group E (15 and 17 mg 100ml-1). Estimated milk yield from forage was considerably higher in group E (15.9 vs 13.5 kg). Efficiency of nitrogen (N) utilization was tendencially higher in group E

Probing the curvature of the Universe from supernova measurement

We study the possibility to probe the spatial geometry of the Universe by supernova measurement of the cubic correction to the luminosity distance. We illustrate with an accelerating universe model with infinite-volume extra dimensions, for which the 1$\sigma$ level supernova results indicate that the Universe is closed.Comment: 8 pages, 3 figures, revised version, accepted for publication in Physics Letters

Consumer perception and communication on welfare in organic laying hen farming

A major reason for increased societal popularity of organic production systems is the growing general discontent with intensive farming practices. However, urbanization leads to limited knowledge of farming and farm animal welfare. Consumers believe organic farming leads to better animal welfare, although most health and welfare issues seen in conventional systems are also found in organic poultry systems. The majority of consumers do not translate attitude and good intention into action, the actual purchase of organic products. Understanding this intention-behaviour gap may lead to increased sales of organic products. Effective communication and education can create trust, added additional values and credibility, and may lead to structured perceptions, convictions, values, norms, knowledge and interests and lead to better understanding of organic farming and farm animal welfare. Merchandising strategies can reduce barriers the consumer may encounter at the moment of decision making

SO(1,1) dark energy model and the universe transition

We suggest a scalar model of dark energy with the SO(1,1) symmetry. The model may be reformulated in terms of a real scalar field $\Phi$ and the scale factor $a$ so that the Lagrangian may be decomposed as that of the real quintessence model plus the negative coupling energy term of $\Phi$ to $a$. The existence of the coupling term $L^c$ leads to a wider range of $w_{\Phi}$ and overcomes the problem of negative kinetic energy in the phantom universe model. We propose a power-law expansion model of univese with time-dependent power, which can describe the phantom universe and the universe transition from ordinary acceleration to super acceleration.Comment: 12 pages. submitted to CQ

The aerothermal environment and material response: A review

Aerothermal environments are discussed with emphasis on the cold dense and warm atmospheres of Saturn and Uranus. The spectral distribution of the incident radiation flux is given for the Saturn nominal entry. Saturn and Uranus stagnation point heat pulses with no ablation are compared. Calculations for small flow rates, important in the Saturn-Uranus nominal type entries, are given to investigate the effects due to the mixing layer separation. Analytical and experimental techniques applicable to flowfield calculations are reviewed with emphasis on two--dimensional flow capabilities. Transport properties are reviewed in terms of flowfield calculations along with radiation transport codes. Various approaches to entry calculations are presented. It is indicated that only certain aspects of the aerothermal environment can be simulated in the laboratory and that although flight experiments are becoming feasible they are so expensive that they are prohibitive. Recommendations for further study are included