Metabolic activity throughout early development of dusky kob Argyrosomus japonicus (Sciaenidae)

The physiology of fishes in the early stages of development remains poorly assessed despite the importance of identifying energy bottlenecks in organisms faced with changing environmental conditions. This study describes the metabolic activity of dusky kob Argyrosomus japonicus throughout its early development, from hatchling to settlement stage. Standard, routine and active metabolic rates (SMR, RMR and AMR, respectively) were assessed to determine the species’ metabolic scope and identify how metabolism changes with growth and development. Distinct metabolic changes occurred in association with developmental changes during the early life stages, with flexion-stage larvae showing significantly reduced metabolic scope (approx. 0.30 µmol O₂ ind.^–1 h^–1), representing an energy bottleneck. Based on these findings, it is likely that larvae of A. japonicus are most susceptible to environmental perturbations during flexion. The variability of metabolic rates during the diel cycle was also assessed and revealed that the early-stage larvae showed no preference for daylight, although settlement-stage juveniles were more active during daylight hours (RMR = 12.78 µmol O₂ ind.^–1 h^–1) than at night (RMR = 5.87 µmol O₂ ind.^–1 h^–1). These results suggest that metabolic measurements of the SMR of A. japonicus larvae can be taken at any time of the diel cycle until the settlement phase, when readings should take place at night.     

Spatial distribution of micrometre‐scale porosity and permeability across the damage zone of a reverse‐reactivated normal fault in a tight sandstone: Insights from the Otway Basin,SE Australia

Knowledge of the permeability structure of fault‐bearing reservoir rocks is fundamental for developing robust hydrocarbon exploration and fluid monitoring strategies. Studies often describe the permeability structure of low porosity host rocks that have experienced simple tectonic histories, while investigations of the influence of faults with multiple‐slip histories on the permeability structure of porous clastic rocks are limited. We present results from an integrated petrophysical, microstructural, and mineralogical investigation of the Eumeralla Formation (a tight volcanogenic sandstone) within the hanging wall of the Castle Cove Fault which strikes 30 km NE–SW in the Otway Basin, southeast Australia. This late Jurassic to Cenozoic‐age basin has experienced multiple phases of extension and compression. Core plugs and thin sections oriented relative to the fault plane were sampled from the hanging wall at distances of up to 225 m from the Castle Cove Fault plane. As the fault plane is approached, connected porosities increase by ca. 10% (17% at 225 m to 24% at 0.5 m) and permeabilities increase by two orders of magnitude (from 0.04 mD at 225 m to 1.26 mD at 0.5 m). Backscattered Scanning Electron Microscope analysis shows that microstructural changes due to faulting have enhanced the micrometre‐scale permeability structure of the Eumeralla Formation. These microstructural changes have been attributed to the formation of microfractures and destruction of original pore‐lining chlorite morphology as a result of fault deformation. Complex deformation, that is, formation of macrofractures, variably oriented microfractures, and a hanging wall anticline, associated with normal faulting and subsequent reverse faulting, has significantly influenced the off‐fault fluid flow properties of the protolith. However, despite enhancement of the host rock permeability structure, the Eumeralla Formation at Castle Cove is still considered a tight sandstone. Our study shows that high‐resolution integrated analyses of the host rock are critical for describing the micrometre‐scale permeability structure of reservoir rocks with high porosities, low permeabilities, and abundant clays that have experienced complex deformation.     

Ordinary and Z-mode emissions from the Jovian polar region

The Ulysses Unified Radio and Plasma (URAP) experiment has detected a new component of Jupiter's radio spectrum in the frequency range from about 10 to 30 kHz. This component is emitted in the magnetoionic ordinary mode from a localized corotating source in the northern polar region. The source is centered at system III longitude 208°, near the meridian containing the North magnetic dipole axis, at a distance of nearly 4R_J from the planet and near the last closed field line. The emission frequency is somewhat above the electron plasma frequency in the source region, but well below the electron gyrofrequency. Accompanying this O-mode emission at lower frequencies is intense Z-mode emission, which is likely to play a significant role in the generation of the O-mode.     

A spatial and temporal analysis of second home ownership in West Wales

A locational analysis is presented of second (or holiday) homes in Cemaes. West Wales Time series tenure data for the period 1960–1977 was collected for every dwelling in the study area By adopting a data collection methodology including systematic local enquiry, it is hoped that this project avoids the main weaknesses of second home studies in Britain. namely definitional problems, data inaccuracy. and lack of an explicit time dimension Moreover, data collection and analysis was planned within an hypothesis testing framework Using elementary statistical techniques, conclusions are drawn as to the factors affecting the spatial distribution of second homes and its evolution over time.     

Granulite-Facies Metamorphism, Granite Falls-Montevideo Area, Minnesota

In the Granite Falls-Montevideo area, Minnesota, granulite faciesmineral assemblages were collected from three major lithologicunits—hornblende-pyroxene gneiss, garnet-biotite gneiss,and granitic gneiss. Mineral assemblages most commonly observedare: plagioclase-hornblende-orthopyroxene-clinopyroxene-magnetite-ilmenite-(biotite-quartz);quartz-plagioclase-biotite-garnet-orthopyroxene-(orthoclase);quartz-plagioclase-biotite-garnet-(orthoclase); quartz-plagioclase-microcline-(garnet-hematite);and quartz-plagio-clase-microcline-biotite-(garnet-hematite-rutile).Partial analyses of isomorphous phases from the hornblende-pyroxenegneiss and the garnet-biotite gneiss were determined with anelectron microprobe. Negligible compositional variation within single grains andof a particular mineral within a given specimen, regular distributionof Fe and Mg between coexisting hornblende, ortho-pyroxene,and clinopyroxene, obedience of the mineral assemblages to theGibbs Phase Rule, and lack of empirically determined incompatiblephases indicate a close approach to chemical equilibrium duringmetamorphism. Plots of coexisting biotite, garnet, and orthopyroxeneon an appropriate phase diagram result in some crossing tielines which cannot be adequately explained by temperature orpressure differences, but suggest that H₂O and/or O₂ were notperfectly mobile components during metamorphism. This is alsoindicated by interlayering of hornblende assemblages with pyroxeneassemblages and by different iron oxide phases in essentiallythe same mineral assemblage. Textural and chemical relationships of retrograde metamorphicassemblages suggest that some retrograde reactions are a resultof cooling following the granulite-facies metamorphism, butthat others may have resulted from recrystallization duringa stage of thermal metamorphism that is reflected in the potassium-argonand rubidium-strontium biotite ages of the metamorphic rocks.     

Earthquake early warning scenarios at critical facilities in the Eastern Caribbean

A feasibility study of an earthquake early warning (EEW) system was conducted for the Eastern Caribbean region using scenario earthquakes, corresponding to the maximum credible earthquakes and to the earthquakes associated with a return period of 475 years. Broadband synthetic seismograms were produced at selected critical facilities, where there is potential interest in the installation of an EEW system. The expected damage was derived from the synthetic seismograms and compared with the lead-time determined for both a regional and on-site EEW configuration. Next, the Virtual Seismologist EEW algorithm, as included in SeisComP3, was tested. Additional broadband synthetic seismograms were produced for the stations in the Eastern Caribbean seismic networks in order to simulate the real time behaviour of the seismic networks during the occurrence of the synthetic earthquakes and to assess the predictive capacity of the selected ground motion prediction equation. Expected peak ground parameters and lead-times at the critical facilities constitute the major outcome of the study.     

Super-orbital period in the high-mass X-ray binary 2S 0114+650

We report the detection of a stable super-orbital period in the high-mass X-ray binary 2S 0114+650. Analyses of data from the Rossi X-ray Timing Explorer All-Sky Monitor from 1996 January 5 to 2004 August 25 reveal a super-orbital period of 30.7±0.1 d, in addition to confirming the previously reported neutron star spin period of 2.7 h and the binary orbital period of 11.6 d. It is unclear if the super-orbital period can be ascribed to the precession of a warped accretion disc in the system.     

Chemical plume tracing via an autonomous underwater vehicle

Olfactory-based mechanisms have been hypothesized for biological behaviors including foraging, mate-seeking, homing, and host-seeking. Autonomous underwater vehicles (AUVs) capable of such chemical plume tracing feats would have applicability in searching for environmentally interesting phenomena, unexploded ordinance, undersea wreckage, and sources of hazardous chemicals or pollutants. This article presents an approach and experimental results using a REMUS AUV to find a chemical plume, trace the chemical plume to its source, and maneuver to reliably declare the source location. The experimental results are performed using a plume of Rhodamine dye developed in a turbulent, near-shore, oceanic fluid flow.     

On the impact of PCA dimension reduction for hyperspectral detection of difficult targets

Due to constraints both at the sensor and on the ground, dimension reduction is a common preprocessing step performed on many hyperspectral imaging datasets. However, this transformation is not necessarily done with the ultimate data exploitation task in mind-for example, target detection or ground cover classification. Indeed, theoretically speaking it is possible that a lossy operation such as dimension reduction might have a negative impact on detection performance. This notion is investigated experimentally using real-world hyperspectral imaging data. The popular principal components transform [aka. principal components analysis (PCA)] is used to explore the impact that dimension reduction has on adaptive detection of difficult targets in both the reflective and emissive regimes. Using seven state-of-the-art algorithms, it is shown that in many cases PCA can have a minimal impact on the detection statistic value for a target that is spectrally similar to the background against which it is sought.