Fish assemblages associated with natural and anthropogenically-modified habitats in a marine embayment: Comparison of baited videos and opera-house traps

Marine embayments and estuaries play an important role in the ecology and life history of many fish species. Cockburn Sound is one of a relative paucity of marine embayments on the west coast of Australia. Its sheltered waters and close proximity to a capital city have resulted in anthropogenic intrusion and extensive seascape modification. This study aimed to compare the sampling efficiencies of baited videos and fish traps in determining the relative abundance and diversity of temperate demersal fish species associated with naturally occurring (seagrass, limestone outcrops and soft sediment) and modified (rockwall and dredge channel) habitats in Cockburn Sound. Baited videos sampled a greater range of species in higher total and mean abundances than fish traps. This larger amount of data collected by baited videos allowed for greater discrimination of fish assemblages between habitats. The markedly higher diversity and abundances of fish associated with seagrass and limestone outcrops, and the fact that these habitats are very limited within Cockburn Sound, suggests they play an important role in the fish ecology of this embayment. Fish assemblages associated with modified habitats comprised a subset of species in lower abundances when compared to natural habitats with similar physical characteristics. This suggests modified habitats may not have provided the necessary resource requirements (e.g. shelter and/or diet) for some species, resulting in alterations to the natural trophic structure and interspecific interactions. Baited videos provided a more efficient and non-extractive method for comparing fish assemblages and habitat associations of smaller bodied species and juveniles in a turbid environment

Hole-doping dependence of percolative phase separation in Pr_(0.5-delta)Ca_(0.2+delta)Sr_(0.3)MnO_(3) around half doping

We address the problem of the percolative phase separation in polycrystalline samples of Pr$_{0.5-\delta}$Ca$_{0.2+\delta}$Sr$_{0.3}$MnO$_3$ for $-0.04\leq \delta \leq 0.04$ (hole doping $n$ between 0.46 and 0.54). We perform measurements of X-ray diffraction, dc magnetization, ESR, and electrical resistivity. These samples show at $T_C$ a paramagnetic (PM) to ferromagnetic (FM) transition, however, we found that for $n>0.50$ there is a coexistence of both of these phases below $T_C$. On lowering $T$ below the charge-ordering (CO) temperature $T_{CO}$ all the samples exhibit a coexistence between the FM metallic and CO (antiferromagnetic) phases. In the whole $T$ range the FM phase fraction ($X$) decreases with increasing $n$. Furthermore, we show that only for $n\leq 0.50$ the metallic fraction is above the critical percolation threshold $X_C\simeq 15.5$. As a consequence, these samples show very different magnetoresistance properties. In addition, for $n\leq 0.50$ we observe a percolative metal-insulator transition at $T_{MI}$, and for $T_{MI}<T<T_{CO}$ the insulating-like behavior generated by the enlargement of $X$ with increasing $T$ is well described by the percolation law $\rho ^{-1}=\sigma \sim (X-X_C)^t$, where $t$ is a critical exponent. On the basis of the values obtained for this exponent we discuss different possible percolation mechanisms, and suggest that a more deep understanding of geometric and dimensionality effects is needed in phase separated manganites. We present a complete $T$ vs $n$ phase diagram showing the magnetic and electric properties of the studied compound around half doping.Comment: 9 text pages + 12 figures, submitted to Phys. Rev.

An overview of thermophotovoltaic generation of electricity

This paper provides an overview of the developments in thermophotovoltaic (TPV) generation of electricity that have occurred relatively recently-from about 1994 to October 1998. The components considered are the semiconductor converter; the radiator; and the means of recirculating unusable, long-wavelength photons. A short account of the functions and performance of each of these components is given. Also discussed are operational systems and progress in modeling TPV systems

High performance transparent conducting films of cadmium indate prepared by RF sputtering

The authors are examining various spinel-structured thin films (e.g., Cd{sub 2}SnO{sub 4}, Zn{sub 2}SnO{sub 4}) to develop higher-quality transparent conducting oxides (TCO) than more conventional materials such as indium tin oxide. Here, the authors report on cadmium indate (CdIn{sub 2}O{sub 4}, CIO), which is another member of this family. Thin films of CIO were deposited by radio-frequency (RF) magnetron sputtering, from an oxide target, onto borosilicate glass substrates. The variables included the substrate temperature, sputtering gas composition, and pressure. Film properties were measured before and after heat treatment. Characterization involved Hall effect measurements, optical and infrared spectrophotometry, X-ray diffraction, and atomic-force microscopy. Film resistivities as low as 2.3 {times} 10{sup {minus}4} {Omega} cm were achieved for a film thickness of 0.55 {micro}m. The transmittance was 90% in the visible region of the spectrum, without correction for substrate losses and without an anti-reflection coating. The plasma resonance occurred at longer wavelengths than for other materials and this, with a bandgap of approximately 3.1 eV, presents a wide window for optical transmittance. The highest mobility was 54 cm{sup 2} V{sup {minus}1} s{sup {minus}1} and the highest carrier concentration was 7.5 {times} 10{sup 20} cm{sup {minus}3}