Nonlinear channelizer.

The nonlinear channelizer is an integrated circuit made up of large parallel arrays of analog nonlinear oscillators, which, collectively, serve as a broad-spectrum analyzer with the ability to receive complex signals containing multiple frequencies and instantaneously lock-on or respond to a received signal in a few oscillation cycles. The concept is based on the generation of internal oscillations in coupled nonlinear systems that do not normally oscillate in the absence of coupling. In particular, the system consists of unidirectionally coupled bistable nonlinear elements, where the frequency and other dynamical characteristics of the emergent oscillations depend on the system's internal parameters and the received signal.

Underwater psychophysical audiogram of a young male California sea lion (Zalophus californianus).

Auditory evoked potential (AEP) data are commonly obtained in air while sea lions are under gas anesthesia; a procedure that precludes the measurement of underwater hearing sensitivity. This is a substantial limitation considering the importance of underwater hearing data in designing criteria aimed at mitigating the effects of anthropogenic noise exposure. To determine if some aspects of underwater hearing sensitivity can be predicted using rapid aerial AEP methods, this study measured underwater psychophysical thresholds for a young male California sea lion (Zalophus californianus) for which previously published aerial AEP thresholds exist.

A sediment ecotoxicity assessment platform for in situ measures of chemistry, bioaccumulation and toxicity. Part 2: Integrated application to a shallow estuary.

A comprehensive, weight-of-evidence based ecological risk assessment approach integrating laboratory and in situ bioaccumulation and toxicity testing, passive sampler devices, hydrological characterization tools, continuous water quality sensing, and multi-phase chemical analyses was evaluated. The test site used to demonstrate the approach was a shallow estuarine wetland where groundwater seepage and elevated organic and inorganic contaminants were of potential concern. Although groundwater was discharging into the surficial sediments, little to no chemical contamination was associated with the infiltrating groundwater.

Subjective loudness level measurements and equal loudness contours in a bottlenose dolphin (Tursiops truncatus).

Loudness level measurements in human listeners are straightforward; however, it is difficult to convey the concepts of loudness matching or loudness comparison to (non-human) animals. For this reason, prior studies have relied upon objective measurements, such as response latency, to estimate equal loudness contours in animals. In this study, a bottlenose dolphin was trained to perform a loudness comparison test, where the listener indicates which of two sequential tones is louder.

Dolphin and sea lion auditory evoked potentials in response to single and multiple swept amplitude tones.

Measurement of the auditory steady-state response (ASSR) is increasingly used to assess marine mammal hearing. These tests normally entail measuring the ASSR to a sequence of sinusoidally amplitude modulated tones, so that the ASSR amplitude function can be defined and the auditory threshold estimated. In this study, an alternative method was employed, where the ASSR was elicited by an amplitude modulated stimulus whose sound pressure level was slowly varied, or "swept," over a range of levels believed to bracket the threshold.

Off-axis detection and characterization of laser beams in the maritime atmosphere.

Remote detection and characterization of laser beams propagating in maritime atmospheres is discussed. A model for off-axis scattered laser light based on Mie scattering from maritime aerosols is presented and compared with angle and time-resolved measurements from a pulsed laser source. We demonstrate that the direction of the source can be determined from the angle-resolved intensity and that the beam direction can be determined from arrival times of the scattered signals if the position of the laser source is known.

California sea lion (Zalophus californianus) aerial hearing sensitivity measured using auditory steady-state response and psychophysical methods.

Although electrophysiological methods of measuring the hearing sensitivity of pinnipeds are not yet as refined as those for dolphins and porpoises, they appear to be a promising supplement to traditional psychophysical procedures. In order to further standardize electrophysiological methods with pinnipeds, a within-subject comparison of psychophysical and auditory steady-state response (ASSR) measures of aerial hearing sensitivity was conducted with a 1.5-yr-old California sea lion.

A postexposure feeding assay using the marine polychaete Neanthes arenaceodentata suitable for laboratory and in situ exposures.

This study examined the suitability for the use of the polychaetous annelid Neanthes arenaceodentata in a short-term sublethal bioassay based on postexposure feeding rate. Quantification of feeding rate was determined by an approximately 1-h feeding period to Artemia franciscana nauplii after a 48-h aqueous exposure. Both lethality and feeding rate were assessed after exposure to Cu and phenanthrene, with the Cu results being compared with those available from similar studies that used the polychaete Hediste diversicolor.

Fate and effects of Composition B in multispecies marine exposures.

The vast majority of investigations into the bioavailability and toxicity of explosives to receptors in aquatic environments has focused on deriving toxicity metrics for discrete chemical exposures to single species using pure compounds at relatively high concentrations. This study assessed the environmental fate and potential for biological effects of a common military formulation, Composition B, under more realistic exposure scenarios (e.g.

Frequency-dependent and longitudinal changes in noise-induced hearing loss in a bottlenose dolphin (Tursiops truncatus).

Temporary threshold shift (TTS) was measured in a bottlenose dolphin (Tursiops truncatus) after exposure to 16-s tones at 3 and 20 kHz to examine the effects of exposure frequency on the onset and growth of TTS. Thresholds were measured approximately one-half octave above the exposure frequency using a behavioral response paradigm featuring an adaptive staircase procedure. Preliminary data provide evidence of frequency-specific differences in TTS onset and growth, and increased susceptibility to auditory fatigue after exposure to 3-kHz tones compared to data obtained two years earlier.

Effects of underwater turbulence on laser beam propagation and coupling into single-mode optical fiber.

We characterize and compare the effects of turbulence on underwater laser propagation with theory. Measurements of the coupling efficiency of the focused beam into a single-mode fiber are reported. A simple tip-tilt control system, based on the position of the image centroid in the focal plane, was shown to maintain good coupling efficiency for a beam radius equal to the transverse coherence length, r(0).

Laser propagation at 1.56 microm and 3.60 microm in maritime environments.

We report results from field experiments that have compared laser propagation at 1.565 microm and 3.603 microm in a variety of atmospheric conditions in a low-altitude maritime environment in order to quantify the relative effects of turbulence under realistic conditions.

Use of phlebotomy treatment in Atlantic bottlenose dolphins with iron overload.

Case Description: 3 adult (24- to 43-year-old) Atlantic bottlenose dolphins (Tursiops truncatus) with chronic episodic malaise and inappetence associated with high serum aminotransferase (alanine aminotransferase and aspartate aminotransferase) activities, high serum iron concentration, and serum transferrin saturation > 80% were evaluated.

Clinical Findings: Results of histologic examination of liver biopsy specimens revealed hemosiderosis in all 3 dolphins. Except for chronic lymphocytosis in 1 dolphin, results of extensive diagnostic testing revealed no other abnormalities.

Modified variance ratio for objective detection of transient evoked potentials in bottlenose dolphins (Tursiops truncatus).

Evoked potential studies have often relied on one or more human observers to visually assess the averaged waveforms and decide if a response is present. Although simple and easy to implement, response detection strategies based on human observers are inherently subjective and depend on the observers' experience and biases. To avoid these shortcomings, some recent marine animal studies utilizing auditory steady-state responses have applied frequency-domain, statistically based objective detection methods; however, statistically based objective methods have not yet been applied to marine animal tests involving transient evoked responses, which are normally analyzed in the time domain.

Thermal tolerance in bottlenose dolphins (Tursiops truncatus).

Water and air temperature are potentially limiting factors to the pole-ward distributions of coastal bottlenose dolphins. This study assessed the lower critical temperature of captive bottlenose dolphins to air temperature (LCT(a)) and water temperature (LCT(w)) through the use of open flow respirometry. Five dolphins, ranging from 14 to 33 years of age and acclimated to the waters of the southern California coast (14.

Comodulation masking release in bottlenose dolphins (Tursiops truncatus).

The acoustic environment of the bottlenose dolphin often consists of noise where energy across frequency regions is coherently modulated in time (e.g., ambient noise from snapping shrimp).

Critical tissue copper residues for marine bivalve (Mytilus galloprovincialis) and echinoderm (Strongylocentrotus purpuratus) embryonic development: conceptual, regulatory and environmental implications.

Critical tissue copper (Cu) residues associated with adverse effects on embryo-larval development were determined for the Mediterranean mussel (Mytilus galloprovincialis) and purple sea urchin (Strongylocentrotus purpuratus) following laboratory exposure to Cu-spiked seawater collected from San Diego Bay, California, USA. Whole body no-observed-effect-residues (NOER) were similar, with means of 21 and 23 microg g(-1) dw, for M. galloprovincialis and S.

Frequency and level dependent masking of the multiple auditory steady-state response in the bottlenose dolphin (Tursiops truncatus).

The potential for interactions between steady-state evoked responses to simultaneous auditory stimuli was investigated in two bottlenose dolphins (Tursiops truncatus). Three experiments were conducted using either a probe stimulus (probe condition) or a probe in the presence of a masker (probe-plus-masker condition). In the first experiment, the probe and masker were sinusoidal amplitude-modulated (SAM) tones.

Primary bacterial pathogens in bottlenose dolphins Tursiops truncatus: needles in haystacks of commensal and environmental microbes.

Bacterial cultures of marine mammal samples often yield multiple genera and species, and it can be difficult to determine if a cultured bacterium is a primary pathogen or an incidental finding. To determine the relative risk of bacterial isolates among Atlantic bottlenose dolphins Tursiops truncatus at the United States Navy Marine Mammal Program (MMP), retrospective data on isolates cultured during June 1987 through June 2007 were organized into a novel, 5-tier risk categorization system limited to sole bacteria cultured from internal organ or fluid samples. Of 2586 bacterial isolates cultured, only 34 (1.

Assessment of increased serum aminotransferases in a managed Atlantic bottlenose dolphin (Tursiops truncatus) population.

Nonspecific chronic hepatitis and increased activities of serum aminotransferases have been reported in cetaceans (dolphins, porpoises, and whales). We identified bottlenose dolphins in our current population with episodic increases in serum aminotransferases, specifically alanine aminotransferase (ALT) and aspartate aminotransferase (AST), and we hypothesized that hematologic and serum biochemical changes in these animals may provide clues as to potential causes of liver disease in cetaceans. A retrospective case-control study involving 1,288 blood samples collected during 1998-2006 from 18 dolphins (six cases and 12 age- and sex-matched healthy controls) was conducted to compare eosinophil and platelet counts; and serum proteins, albumin, globulins, bilirubin, gamma glutamyltransferase (GGT), cholesterol, triglycerides, glucose, iron, and erythrocyte sedimentation rates.

Measurement of low-altitude infrared propagation.

Infrared propagation at low altitudes is determined by extinction that is due to molecules and aerosol particles and ray bending by refraction, three effects that control the mean value of the signal. Interference causes the signal to fluctuate, or scintillate, about the mean value. We discuss the design, calibration, and limitations of a field instrument for measuring optical propagation inside the midwave and long-wave infrared atmospheric windows.

High bandwidth underwater optical communication.

We report error-free underwater optical transmission measurements at 1 Gbit/s (10(9) bits/s) over a 2 m path in a laboratory water pipe with up to 36 dB of extinction. The source at 532 nm was derived from a 1064 nm continuous-wave laser diode that was intensity modulated, amplified, and frequency doubled in periodically poled lithium niobate. Measurements were made over a range of extinction by the addition of a Mg(OH)(2) and Al(OH)(3) suspension to the water path, and we were not able to observe any evidence of temporal pulse broadening.

Estimating bottlenose dolphin (Tursiops truncatus) hearing thresholds from single and multiple simultaneous auditory evoked potentials.

Hearing thresholds were estimated in four bottlenose dolphins by measuring auditory evoked responses to single and multiple sinusoidal amplitude modulated tones. Subjects consisted of two males and two females with ages from 4 to 22 years. Testing was conducted in air using a "jawphone" transducer to couple sound into each subject's lower right jaw.