Search Results - (Author, Cooperation:B. A. Block)

2014-02-18

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Animals ; Arrhythmias, Cardiac/chemically induced/*veterinary ; Calcium/metabolism ; Delayed Rectifier Potassium Channels/antagonists & inhibitors ; Heart Ventricles/*drug effects ; Myocardial Contraction/*drug effects ; Myocytes, Cardiac/drug effects/physiology ; Petroleum/*toxicity ; *Petroleum Pollution ; Tuna/*physiology ; Ventricular Function/drug effects

2011-06-24

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Animal Identification Systems ; Animal Migration ; Animals ; Aquatic Organisms/*physiology ; Bayes Theorem ; Biodiversity ; California ; Climate ; *Ecosystem ; Locomotion/*physiology ; North America ; Pacific Ocean ; Population Dynamics ; Predatory Behavior/*physiology ; Seasons ; Species Specificity ; Water Movements ; Wilderness

2018-02-23

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Geosciences

Computer Science

Medicine

Natural Sciences in General

Physics

Ecology, Geochemistry, Geophysics

2018-08-24

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Geosciences

Computer Science

Medicine

Natural Sciences in General

Physics

Ecology, Techniques

2018-03-09

American Association for the Advancement of Science (AAAS)

2375-2548

Natural Sciences in General

1077-3118

AIP Digital Archive

Physics

We report on the fabrication of channel waveguides in epitaxial grown BaTiO3 layers on MgO. Layers were prepared by metalorganic chemical vapor deposition. Ridge waveguides with ridge heights ranging from 15 to 200 nm were fabricated in a 0.2-μm-thick film. Single mode waveguide throughput, scattering loss, and mode profiles are reported. Coating waveguides with spin on glass significantly increase waveguide throughput. Throughputs of up to 10.4% were measured in 15 nm ridge waveguides which were 2.85 mm long and coated with spin on glass. Waveguide throughput is found to increase significantly with an increase in wavelength from 1.06 to 1.55 μm. © 1996 American Institute of Physics.

Electronic Resource

1077-3118

AIP Digital Archive

Physics

Er3+-doped BaTiO3 thin films were grown on Si (100) by metalorganic chemical vapor deposition. Strong characteristic Er3+ intra-4f shell emission at 0.80 eV is observed at 16 and 295 K. The Er3+ luminescence intensity is linearly dependent on the pump power. Photoluminescence lifetimes were found to be on the order of 8 ms. These results indicate that Er-doped BaTiO3 has potential as an optically active, nonlinear waveguide medium.

Electronic Resource

1095-8649

Blackwell Publishing Journal Backfiles 1879-2005

Biology

A sharptail mola Masturus lanceolatus was tagged and released with a pop-up satellite archival tag in the Gulf of Mexico and tracked for 61 days. The fish travelled a horizontal distance of 594 km while generally staying in water 〈200 m depth and 〉20° C. Occasionally the sharptail mola dived to depths 〉700 m and experienced water colder than 6° C.

Electronic Resource

1432-1793

Springer Online Journal Archives 1860-2000

Biology

Abstract We measured the horizontal and vertical movements of five adult yellowfin tuna (Thunnus albacares, estimated body mass 64 to 93 kg) near the main Hawaiian Islands, while simultaneously gathering data on oceanographic conditions and currents. Fish movements were recorded by means of ultrasonic depth-sensitive transmitters. Depth–temperature and depth–oxygen profiles were measured with vertical conductivity–temperature–depth (CTD) casts, and the current-velocity field was surveyed using an acoustic Doppler current profiler (ADCP). Large adult yellowfin tuna spent ≃60 to 80% of their time in or immediately below the relatively uniform-temperature surface-layer (i.e. above 100 m), a behavior pattern similar to that previously reported for juvenile yellowfin tuna, blue marlin (Makaira nigricans), and striped marlin (Tetrapturus audax) tracked in the same area. In all three species, maximum swimming depths appear to be limited by water temperatures 8 C° colder than the surface-layer water temperature. Therefore, neither large body mass, nor the ability to maintain elevated swimming-muscle temperatures due to the presence of vascular counter-current heat exchangers in tunas, appears to permit greater vertical mobility or the ability to remain for extended periods below the thermocline. In those areas where the decrease in oxygen with depth is not limiting, the vertical movements of yellowfin tuna, blue marlin and striped marlin all appear to be restricted by the effects of water temperature on cardiac muscle function. Like juvenile yellowfin tuna, but unlike blue marlin and striped marlin, adult yellowfin tuna remained within 18.5 km of the coast and became associated with floating objects, including anchored fish-aggregating devices (FADs) and the tracking vessel. Like juvenile yellowfin tuna, large adult yellowfin repeatedly re-visit the same FAD, and appear able to navigate precisely between FADs that are up to 18 km apart. The median speed over ground ranged from 72 to 154 cm s−1. Neither speed nor direction was strongly influenced by currents.

Electronic Resource

1432-1793

Springer Online Journal Archives 1860-2000

Biology

Abstract Multiplex acoustic transmitters were used to monitor the depth, swimming speeds, body temperature and water temperature preference of six blue marlin, Makaira nigricans (Lacépède), near the Hawaiian islands in July and August 1989. The blue marlin ranged in size from 60 to 220 kg and were tracked for 1 to 5 d. All of the fish moved away from the point of capture and were followed up to 253 km from the island of Hawaii. The blue marlin tracked remained in the top 200 m of the water column, spending half the time in the upper 10 m, and rarely ventured below the thermocline. In the nearsurface waters the temperature was uniformly warm (25 to 27°C). The coldest water temperature, 17°C, was encountered on the deepest descent recorded (209 m). Depth changes occurred rapidly and excursions below 10 m were usually less than 60 min in duration. Muscle temperature was similar to water temperature except for a 2°C elevation in muscle temperature observed at the beginning of tracking one individual. This initial rise in body temperature was associated with the anaerobic muscle activity during capture and is an indication of the physiological stress involved in capture.

Electronic Resource

1432-1793

Springer Online Journal Archives 1860-2000

Biology

Abstract We used acoustic telemetry to examine the small-scale movement patterns of yellowfin tuna (Thunnus albacares) in the California Bight at the northern extent of their range. Oceanographic profiles of temperature, oxygen, currents and fluorometry were used to determine the relationship between movements and environmental features. Three yellowfin tuna (8 to 16 kg) were tracked for 2 to 3 d. All three fish spent the majority of their time above the thermocline (18 to 45 m in depth) in water temperatures 〉17.5 °C. In the California Bight, yellowfin tuna have a limited vertical distribution due to the restriction imposed by temperature. The three fish made periodic short dives below the thermocline (60 to 80 m), encountering cooler temperatures (〉11 °C). When swimming in northern latitudes, the depth of the mixed layer largely defines the spatial distribution of yellowfin tuna within the water column. Yellowfin prefer to spend most of their time just above the top of the thermocline. Oxygen profiles indicated that the tunas encountered oceanic water masses that ranged most often from 6.8 to 8.6 mg O2 l−1, indicating no limitation due to oxygen concentrations. The yellowfin tuna traveled at speeds ranging from 0.46 to 0.90 m s−1 (0.9 to 1.8 knots h−1) and frequently exhibited an oscillatory diving pattern previously suggested to be a possible strategy for conserving energy during swimming.

Electronic Resource

1432-1793

Springer Online Journal Archives 1860-2000

Biology

Abstract  The swordfish Xiphias gladius is a migratory oceanic species distributed in sub-tropical and temperate waters worldwide. Studies utilizing mitochondrial DNA (mtDNA) have demonstrated genetic subdivision between ocean basins, as well as within the Atlantic basin. However, there has been no support of population subdivision within the Pacific. We sequenced 629 base pairs of the control region for 281 swordfish collected in the Pacific. A rate heterogeneity parameter, alpha, was found to be 0.201, indicating substantial variation in mutation rate within the control region of swordfish. Hierarchical analysis of molecular variance supported significant genetic structuring among Pacific populations. Northern and southern populations in the western Pacific were significantly divergent, while populations in the east appeared to be genetically continuous. Regression analysis supported a correlation of genetic differentiation with geographic distance along a U-shaped corridor of gene flow. These results reveal a pelagic biogeographic pattern heretofore unrecognized in the Pacific, and reject the null hypothesis that Pacific populations of swordfish are unstructured and comprise only a single homogeneous stock.

Electronic Resource

1432-1793

Springer Online Journal Archives 1860-2000

Biology

Abstract Little is known about what limits genetic exchange in highly vagile, open ocean vertebrate species, such as the swordfish Xiphias gladius L. Reduced abundance of swordfish in some regions, and increased fishing pressure in others, has raised concerns and fueled interest in a more complete evaluation of the resource. In this study, global population structure in swordfish was assessed by sequencing a 300 base pair segment of the 5′ end of mitochondrial DNA control region from 159 swordfish collected in three ocean basins: the Mediterranean, Atlantic and Pacific, over the years 1988 to 1994. Among the 159 individuals, 95 polymorphic sites delineated 121 unique haplotypes, indicating a high level of polymorphism on a global scale. A phylogenetic analysis of the unique DNA haplotypes revealed two divergent clades with differing geographic distributions. Phylogeographic concordance of this pattern with that of two other pelagic fish species suggests a biogeographic explanation for this structure. An analysis of molecular variance (AMOVA) revealed significant geographic partitioning of molecular variation among the three ocean basins, indicating that swordfish populations are structured on a global scale. Estimates of genetic exchange among populations within an ocean basin were high, indicating panmixia within ocean basins. Since the haplotypic diversity exhibited by the swordfish control regions is extremely high, much larger sample sizes may be necessary to detect subdivision within ocean basins.

Electronic Resource