Vocal rhythms in nesting Lusitanian toadfish, Halobatrachus didactylus

Males of several fish species aggregate and vocalize together, increasing the detection range of the sounds and their chances of mating. In the Lusitanian toadfish (Halobatrachus didactylus), breeding males build nests under rocks in close proximity and produce hundreds of boatwhistles (BW) an hour to attract females to lay their demersal eggs on their nests. Chorusing behaviour includes fine-scale interactions between individuals, a behavioural dynamic worth investigating in this highly vocal fish. Here we present a study to further investigate this species’ vocal temporal patterns on a fine (individual rhythms and male-male interactions) and large (chorus daily patterns) scales. Several datasets recorded in the Tagus estuary were labelled with the support of an automatic recognition system based on hidden Markov models. Fine-scale vocal temporal patterns exhibit high variability between and within individuals, varying from an almost isochronous to an apparent aperiodic pattern. When in a chorus, males exhibited alternation or synchrony calling patterns, possibly depending on motivation and social context (mating or male-male competition). When engaged in sustained calling, males usually alternated vocalizations with their close neighbours thus avoiding superposition of calls. Synchrony was observed mostly in fish with lower mean calling rate. Interaction patterns were less obvious in more distanced males. Daily choruses showed periods with several active calling males and periods of low activity with no significant diel patterns in shallower intertidal waters. Here, chorusing activity was mainly affected by tide level. In contrast, at a deeper location, although tidal currents causes a decrease in calling rate, tide level did not significantly influence calling, and there was a higher calling rate at night. These data show that photoperiod and tide levels can influence broad patterns of Lusitanian toadfish calling activity as in other shallow-water fishes, but fine temporal patterns in acoustic interactions among nesting males is more complex than previously known for fishes.Fundação para a Ciência e Tecnologia - FCTinfo:eu-repo/semantics/publishedVersio

Biometrics

Biometrics-Unique and Diverse Applications in Nature, Science, and Technology provides a unique sampling of the diverse ways in which biometrics is integrated into our lives and our technology. From time immemorial, we as humans have been intrigued by, perplexed by, and entertained by observing and analyzing ourselves and the natural world around us. Science and technology have evolved to a point where we can empirically record a measure of a biological or behavioral feature and use it for recognizing patterns, trends, and or discrete phenomena, such as individuals' and this is what biometrics is all about. Understanding some of the ways in which we use biometrics and for what specific purposes is what this book is all about

A cumulative index to Aeronautical Engineering: A special bibliography, January 1976

This publication is a cumulative index to the abstracts contained in NASA SP-7037 (54) through NASA SP-7037 (65) of Aeronautical Engineering: A Special Bibliography. NASA SP-7037 and its supplements have been compiled through the cooperative efforts of the American Institute of Aeronautics and Astronautics (AIAA) and the National Aeronautics and Space Administration (NASA). This cumulative index includes subject, personal author, corporate source, contract, and report number indexes

Energy: A continuing bibliography with indexes, issue 20

A bibliography is presented which lists 1250 reports, articles, and other documents introduced into the NASA Scientific and Technical Information System from October 1, 1978 through December 31, 1978

Utilizing the 3D Environment to Facilitate Learning of Complex Visual Neural Pathways in the Avian Brain

Neuroanatomical pathways are difficult to study often due to the limit of methods used to visualize the anatomical and physiologic characteristics. In many studies, a neural pathway is presented using 2D representations for structural connectivity. A problem is deciding which of three planes: coronal, sagittal, or horizontal is best for visualizing the pathway’s components clearly and spatially precise for those wanting to learn and utilize that information. A 3D environment would be imperative in solving this issue. We therefore attempted to develop a means of accurately presenting detailed anatomical structures within the 3D regions they occurred. It is our hope that accurate, spatial representations of visual neural pathways will result in learning specific structures, their subdivisions, and their spatial organizations. Advancements in imaging techniques address this issue and have allowed for a new avenue of investigation for studying the morphology of anatomical systems. One such technique, diffusible iodine-based contrast-enhanced computed tomography (diceCT), has allowed for nondestructive visualization of an appropriately fixed brain. In other words, it allows one to image the entire brain, and visualize any of the three planes without damaging the specimen. We have chosen the visual tectofugal and thalamofugal pathways in an avian brain as they are some of the most well studied systems that seems to have much disparity in their anatomical organization and connectivity. The tectofugal pathway begins in the eyeball with retinal ganglion cells projecting to the optic tectum which in turn send projections to a thalamic nucleus. This thalamic nucleus then projects to a region of the forebrain, completing the ascending pathway. The thalamofugal pathway begins in the eyeball with retinal ganglion cells projecting to the lateral geniculate complex, which in turn projects bilaterally to a large terminal forebrain structure occupying the dorsomedial brain surface. For our investigation we employed two techniques: (1) a series of stacked histologic sections of four chick brains, and (2) a diceCT stained whole brain of a chick. For histological sections, we used series of coronal, sagittal, and horizontal sections stained with Nissl (cell bodies revealed) and Luxol Fast Blue or Gallyas silver myelin (fiber tracts revealed). Sections were imported into Brainmaker (Microbrightfield Biosciences), a software that stacks image sequences and reconstructs volumes based on sequential contours. For our diceCT investigation, we rendered the eyeball and brain within the skull of the bird. This allowed an accurate spatial representation of the eyeball with respect to the brain. Post model processing was essential to integrate detailed 2D images in the appropriate plane of the 3D environment. Using the histological image stacks, diceCT scanned eye and brain, and 3D editing software, we created an interactive 3D model of the avian visual tectofugal and thalamofugal pathways. The combination of histochemical sections with diceCT 3D modeling is necessary when detailed anatomical and spatial organization of complex neural pathways such as the tectofugal visual system are desired

Utilizing the 3D Environment to Facilitate Learning of Complex Visual Neural Pathways in the Avian Brain

Neuroanatomical pathways are difficult to study often due to the limit of methods used to visualize the anatomical and physiologic characteristics. In many studies, a neural pathway is presented using 2D representations for structural connectivity. A problem is deciding which of three planes: coronal, sagittal, or horizontal is best for visualizing the pathway’s components clearly and spatially precise for those wanting to learn and utilize that information. A 3D environment would be imperative in solving this issue. We therefore attempted to develop a means of accurately presenting detailed anatomical structures within the 3D regions they occurred. It is our hope that accurate, spatial representations of visual neural pathways will result in learning specific structures, their subdivisions, and their spatial organizations. Advancements in imaging techniques address this issue and have allowed for a new avenue of investigation for studying the morphology of anatomical systems. One such technique, diffusible iodine-based contrast-enhanced computed tomography (diceCT), has allowed for nondestructive visualization of an appropriately fixed brain. In other words, it allows one to image the entire brain, and visualize any of the three planes without damaging the specimen. We have chosen the visual tectofugal and thalamofugal pathways in an avian brain as they are some of the most well studied systems that seems to have much disparity in their anatomical organization and connectivity. The tectofugal pathway begins in the eyeball with retinal ganglion cells projecting to the optic tectum which in turn send projections to a thalamic nucleus. This thalamic nucleus then projects to a region of the forebrain, completing the ascending pathway. The thalamofugal pathway begins in the eyeball with retinal ganglion cells projecting to the lateral geniculate complex, which in turn projects bilaterally to a large terminal forebrain structure occupying the dorsomedial brain surface. For our investigation we employed two techniques: (1) a series of stacked histologic sections of four chick brains, and (2) a diceCT stained whole brain of a chick. For histological sections, we used series of coronal, sagittal, and horizontal sections stained with Nissl (cell bodies revealed) and Luxol Fast Blue or Gallyas silver myelin (fiber tracts revealed). Sections were imported into Brainmaker (Microbrightfield Biosciences), a software that stacks image sequences and reconstructs volumes based on sequential contours. For our diceCT investigation, we rendered the eyeball and brain within the skull of the bird. This allowed an accurate spatial representation of the eyeball with respect to the brain. Post model processing was essential to integrate detailed 2D images in the appropriate plane of the 3D environment. Using the histological image stacks, diceCT scanned eye and brain, and 3D editing software, we created an interactive 3D model of the avian visual tectofugal and thalamofugal pathways. The combination of histochemical sections with diceCT 3D modeling is necessary when detailed anatomical and spatial organization of complex neural pathways such as the tectofugal visual system are desired

A cumulative index to Aeronautical Engineering: A special bibliography

This publication is a cumulative index to the abstracts contained in NASA SP-7037 (80) through NASA SP-7037 (91) of Aeronautical Engineering: A Special Bibliography. NASA SP-7037 and its supplements have been compiled through the cooperative efforts of the American Institute of Aeronautics (AIAA) and Space Administration (NASA). This cumulative index includes subject, personal author, corporate source, contract, and report number indexes

Passive acoustic monitoring for assessment of natural and anthropogenic sound sources in the marine environment using automatic recognition

In the marine environment, sound can be an efficient source of information. Indeed, several marine species, including fish, use sound to navigate, select habitats, detect predators and prey, and to attract mates. Therefore, all the abiotic, biotic and manmade sounds that comprise the soundscape, have the potential to be used to assess and monitor species and marine environments. Passive acoustic monitoring (PAM) involves the use of acoustic sensors to record sound in the environment, from which relevant ecological information can be inferred. This thesis studied marine soundscapes, with special attention on fish communities, anthropogenic noise, and applied several methods to analyse acoustic recordings. Most of the focus was on the Tagus estuary, where the presence of two highly vocal species is known: the Lusitanian toadfish (Halobatrachus didactylus) and the meagre (Argyrosomus regius). Azorean and Mozambique soundscapes were also analysed. Several methods were applied to extract information and to visualize soundscape characteristics, including sound recognition systems based on hidden Markov models to recognize fish sounds and boat passages. Analysis of several types of marine environments and time scales showed several advantages and disadvantages of different methods. The use of sound pressure level on different frequency bands allowed the quantification of daily and seasonal patterns. Ecoacoustic indices appear to be cost-effective tools to monitor biodiversity in some marine environments. Using automatic recognition, vocal rhythms (diel and seasonal patterns) and vocal interactions among individuals were also characterized. Furthermore, boat noise effects on fish were studied: we encountered impacts on the audition, vocal behaviour and reproduction. Overall, we used PAM as a tool to remotely assess and monitor soundscapes, biodiversity, fish communities’ seasonal patterns, fish behaviour, species presence, and the effect of anthropogenic noise aiming to contribute for the management and conservation of marine ecosystems

Electroretinographic Mapping of Retinal Function: Evaluation and Clinical Application

The conventional electroretinogram (ERG) is an electrophysiological examination that is used to assess the extent of retinal function within the eye. The test exploits the retina's ability to convert photons of light into electrical impulses. A flash stimulus is employed to evoke an electrical potential within the retinal cells (cones, rods and bipolar cells). These potentials, generated in the retina, are then recorded at the corneal surface of the eye using a contact lens or scleral electrode. The electrical potential generated possesses several distinct components that can be used to locate dysfunction from discrete layers of the retina. Although the ERG is used routinely in the diagnosis and monitoring of a wide range of retinal disorders its application is restricted because the diffuse stimulation of the retina evokes a global response thereby preventing the detection of localised abnormalities. A new technique has recently been developed, the Visual Evoked Response Imaging System (VERIS), which overcomes some of the shortfalls of the conventional electroretinogram. This new method allows functional mapping of the retina by the ERG. The technique enables simultaneous recording from a large number of retinal areas. Each area is independently stimulated in a sequence employing Pseudo Random Binary Sequences (PRBS). The sequences of stimulation are uncorrelated (achieved by temporal modulation of the sequence for each area) therefore the individual responses from different areas of the retina can be extracted. This thesis describes the evaluation of this system with regards to its potential within routine clinical practice. A number of investigations were performed to fulfil this evaluation. Possible factors that may influence the integrity of data obtained from the new technique were investigated and, where possible, minimised. These factors included quantifying the effects of filtering bandwidth, refractive errors, electrode type, response measurement method, luminance, contrast, dilation and the artefacts associated with poor patient shielding (from extraneous electromagnetic interference). The findings from these investigations were used to optimise the recovery of local ERG responses and established a protocol for future investigations. A custom software program was developed for analysis and interpretation of data. A study was undertaken to quantify the repeatability and reproducibility of the technique and to provide normative values. Finally these results were used to assess the techniques ability to objectively detect and quantify several retinal disorders. The investigations indicated that the system was of particular benefit in the assessment of local retinal pathology. However the system suffered a higher exclusion criteria than conventional electrophysiology and was unable, in the clinical setting, to identify retinal pathologies selectively affecting the ganglion cell layer. These factors limited the systems application within clinical practice. Current developments are aimed at improving the technique and establishing a routine clinical test with improved sensitivity and specificity that can be successfully applied to a wider population group

Bibliography of Lewis Research Center technical contributions announced in 1976

Abstracts of Lewis authored publications and publications resulting from Lewis managed contracts which were announced in the 1976 issues of STAR (Scientific and Technical Aerospace Reports) and IAA (International Aerospace Abstracts) are presented. Research reports, journal articles, conference presentations, patents and patent applications, and these are included. The arrangement is by NASA subject category. Citations indicate report literature (identified by their N-numbers) and the journal and conference presentations (identified by their A-numbers). A grouping of indexes helps locate specific publications by author (including contractor authors), contractor organization, contract number, and report number