scholarly journals Target Strength and swimbladder morphology of Mueller’s pearlside (Maurolicus muelleri)

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
B. Sobradillo ◽  
G. Boyra ◽  
U. Martinez ◽  
P. Carrera ◽  
M. Peña ◽  
...  
Keyword(s):  
Relevant Information ◽  
Target Strength ◽  
Fish Length ◽  
Mesopelagic Fish ◽  
Bay Of Biscay ◽  
Numerical Abundance ◽  
Density Filter ◽  
Pressure Changes ◽  
First Time ◽  
Best Fit

AbstractIn the last few years, there has been increasing interest in the commercial exploitation of mesopelagic fish and a trawl-acoustic methodology has been recommended to make estimates of abundance of these resources. This study provides relevant information on the scattering properties of a key mesopelagic fish species in the Bay of Biscay, Mueller’s pearlside (Maurolicus muelleri), necessary to convert the acoustic density into numerical abundance. The target strength (TS) of pearlside was estimated for the first time at five frequencies commonly used in acoustic surveys. A high-density filter was applied to reduce the bias derived from overlapping echoes erroneously assigned to single targets. Its relationship with fish length (b20) was also determined (−65.9 ± 2, −69.2 ± 3, −69.2 ± 2, −69.5 ± 2.5 and −71.5 ± 2.5 dB at 18, 38, 70, 120 and 200 kHz, respectively). Biomass estimates of pearlside in the Bay of Biscay during the four years of study (2014–2017) are given using the 38 kHz frequency. Morphological measurements of the swimbladder were obtained from soft X-ray images and used in the backscattering simulation of a gas-filled ellipsoid. Pearlside is a physoclist species, which means that they can compensate the swimbadder volume against pressure changes. However, the best fit between the model and the experimental data showed that they lose that capacity during the trawling process, when the swimbladder volume is affected by Boyle’s law.

A Comparison of Airline Safety Videos in Information Acquisition

2017 ◽  
Vol 61 (1) ◽  
pp. 1671-1673 ◽  
Author(s):  
Allison Ragan ◽  
Tessa Sommer ◽  
Frank Drews
Keyword(s):  
Information Acquisition ◽  
Safety Information ◽  
Relevant Information ◽  
Flight Safety ◽  
Information Retention ◽  
Short Answer ◽  
Airline Safety ◽  
Short Answer Questions ◽  
First Time

This study examined the effect of humor on airline safety information retention. Passenger attention to pre- flight safety demonstrations is low, even though it may impact the chance of survival in an aviation accident. Airlines have employed humor and entertainment to educate passengers on safety information. This study explored whether the humorous presentation increases retention of safety information, or if humor acts as a distraction from safety relevant information. Participants viewed two pre-flight safety demonstration videos (humorous and non-humorous) in counterbalanced order then answered short-answer questions about the content of the videos. Retention scores after viewing either type of video for the first time were the same. However, when a humorous video was shown prior to a standard safety video, retention scores for safety material dropped. These findings suggest that humorous safety demonstrations may be more effective, not because they are best at conveying information, but because passengers do not attend to standard videos if they have previously been exposed to a humorous version.

scholarly journals Neutron-capture elements in dwarf galaxies

2020 ◽  
Vol 634 ◽  
pp. A84 ◽  
Author(s):  
Á. Skúladóttir ◽  
C. J. Hansen ◽  
A. Choplin ◽  
S. Salvadori ◽  
M. Hampel ◽  
...  
Keyword(s):  
Massive Star ◽  
Milky Way ◽  
Dwarf Galaxies ◽  
Asymptotic Giant Branch ◽  
Agb Stars ◽  
Chemical Enrichment ◽  
Theoretical Predictions ◽  
Low Metallicity ◽  
First Time ◽  
Best Fit

The slow (s) and intermediate (i) neutron (n) capture processes occur both in asymptotic giant branch (AGB) stars, and in massive stars. To study the build-up of the s- and i-products at low metallicity, we investigate the abundances of Y, Ba, La, Nd, and Eu in 98 stars, at −2.4 <  [Fe/H] <  −0.9, in the Sculptor dwarf spheroidal galaxy. The chemical enrichment from AGB stars becomes apparent at [Fe/H] ≈ −2 in Sculptor, and causes [Y/Ba], [La/Ba], [Nd/Ba] and [Eu/Ba] to decrease with metallicity, reaching subsolar values at the highest [Fe/H] ≈ −1. To investigate individual nucleosynthetic sites, we compared three n-rich Sculptor stars with theoretical yields. One carbon-enhanced metal-poor (CEMP-no) star with high [Sr, Y, Zr] >  +0.7 is best fit with a model of a rapidly-rotating massive star, the second (likely CH star) with the i-process, while the third has no satisfactory fit. For a more general understanding of the build-up of the heavy elements, we calculate for the first time the cumulative contribution of the s- and i-processes to the chemical enrichment in Sculptor, and compare with theoretical predictions. By correcting for the r-process, we derive [Y/Ba]s/i = −0.85 ± 0.16, [La/Ba]s/i = −0.49 ± 0.17, and [Nd/Ba]s/i = −0.48 ± 0.12, in the overall s- and/or i-process in Sculptor. These abundance ratios are within the range of those of CEMP stars in the Milky Way, which have either s- or i-process signatures. The low [Y/Ba]s/i and [La/Ba]s/i that we measure in Sculptor are inconsistent with them arising from the s-process only, but are more compatible with models of the i-process. Thus we conclude that both the s- and i-processes were important for the build-up of n-capture elements in the Sculptor dwarf spheroidal galaxy.

scholarly journals Analysis of Pressure Communication between the Austin Chalk and Eagle Ford Reservoirs during a Zipper Fracturing Operation

Energies ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1469 ◽  
Author(s):  
Sriniketh Sukumar ◽  
Ruud Weijermars ◽  
Ibere Alves ◽  
Sam Noynaert
Keyword(s):  
Hydraulic Fracturing ◽  
Field Data ◽  
Pressure Increase ◽  
Rapid Decline ◽  
Residual Pressure ◽  
Eagle Ford ◽  
Austin Chalk ◽  
Temporal Pressure ◽  
Pressure Changes ◽  
First Time

The recent interest in redeveloping the depleted Austin Chalk legacy field in Bryan (TX, USA) mandates that reservoir damage and subsurface trespassing between adjacent reservoirs be mitigated during hydraulic fracture treatments. Limiting unintended pressure communication across reservoir boundaries during hydraulic fracturing is important for operational efficiency. Our study presents field data collected in fall 2017 that measured the annular pressure changes that occurred in Austin Chalk wells during the zipper fracturing treatment of two new wells in the underlying Eagle Ford Formation. The data thereby obtained, along with associated Eagle Ford stimulation reports, was analyzed to establish the degree of pressure communication between the two reservoirs. A conceptual model for pressure communication is developed based on the pressure response pattern, duration, and intensity. Additionally, pressure depletion in the Austin Chalk reservoir is modeled based on historic production data. Pressure increases observed in the Austin Chalk wells were about 6% of the Eagle Ford injection pressures. The pressure communication during the fracture treatment was followed by a rapid decline of the pressure elevation in the Austin Chalk wells to pre-fracture reservoir pressure, once the Eagle Ford fracture operation ended. Significant production uplifts occurred in several offset Austin Chalk wells, coeval with the observed temporal pressure increase. Our study confirms that after the rapid pressure decline following the short-term pressure increase in the Austin Chalk, no residual pressure communication remained between the Austin Chalk and Eagle Ford reservoirs. Limiting pressure communication between adjacent reservoirs during hydraulic fracturing is important in order to minimize the loss of costly fracturing fluid and to avoid undue damage to the reservoir and nearby wells via unintended proppant pollution. We provide field data and a model that quantifies the degree of pressure communication between adjacent reservoirs (Austin Chalk and Eagle Ford) for the first time.

scholarly journals Phylogeny of Anopheles (Kerteszia) (Diptera: Culicidae) Using Mitochondrial Genes

Insects ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 324 ◽  
Author(s):  
Karin Kirchgatter ◽  
Lilian de Oliveira Guimarães ◽  
Henrry Hugo Yañez Trujillano ◽  
Fernando Rafael Arias ◽  
Abraham Cáceres ◽  
...  
Keyword(s):  
Dna Sequences ◽  
Species Recognition ◽  
Phylogenetic Analyses ◽  
Mosquito Species ◽  
Relevant Information ◽  
Neotropical Region ◽  
Similar Species ◽  
Serra Do Mar ◽  
Additional Tool ◽  
First Time

Identification of mosquito species is necessary for determining the entomological components of malaria transmission, but it can be difficult in morphologically similar species. DNA sequences are largely used as an additional tool for species recognition, including those that belong to species complexes. Kerteszia mosquitoes are vectors of human and simian malaria in the Neotropical Region, but there are few DNA sequences of Kerteszia species in public databases. In order to provide relevant information about diversity and improve knowledge in taxonomy of Kerteszia species in Peru, we sequenced part of the mitochondrial genome, including the cytochrome c oxidase I (COI) barcode region. Phylogenetic analyses structured all species of mosquitoes collected in Peru into a single clade, separate from the Brazilian species. The Peruvian clade was composed of two lineages, encompassing sequences from Anopheles (Kerteszia) boliviensis and Anopheles (Kerteszia) pholidotus. An. pholidotus sequences were recorded for the first time in Peru, whereas An. boliviensis sequences were for the first time published in the GenBank database. Sequences generated from specimens morphologically identified as Anopheles (Kerteszia) cruzii clustered into three separate clades according to the collection localities of Serra do Mar, Serra da Mantiqueira, and Serra da Cantareira, confirming An. cruzii as a species complex, composed of at least three putative species.

scholarly journals Swimbladder Morphology and Target Strength of a Mesopelagic Fish, Maurolicus japonicus

2009 ◽  
Vol 36 (4) ◽  
pp. 241-249 ◽  
Author(s):  
Tadanori FUJINO ◽  
Kazuhiro SADAYASU ◽  
Koki ABE ◽  
Hideaki KIDOKORO ◽  
Yongjun TIAN ◽  
...  
Keyword(s):  
Target Strength ◽  
Mesopelagic Fish

scholarly journals Spatially explicit estimation of fish length histograms, with application to anchovy habitats in the Bay of Biscay

2011 ◽  
Vol 68 (10) ◽  
pp. 2086-2095 ◽  
Author(s):  
Pierre Petitgas ◽  
Mathieu Doray ◽  
Jacques Massé ◽  
Patrick Grellier
Keyword(s):  
Stock Assessment ◽  
Spatially Explicit ◽  
Fish Length ◽  
Bay Of Biscay ◽  
Length Frequency ◽  
Polynomial Coefficients ◽  
Complex Information ◽  
Novel Approach ◽  
Frequency Map ◽  
Spatially Varying

Abstract Petitgas, P., Doray, M., Massé, J., and Grellier, P. 2011. Spatially explicit estimation of fish length histograms, with application to anchovy habitats in the Bay of Biscay. – ICES Journal of Marine Science, 68: 2086–2095. Fish length frequency histograms from research surveys are of prime importance for identifying habitats of different life stages, as well as for stock assessment. However, no method has thus far been available for mapping these histograms as spatially varying curves. Here, a procedure is applied to map spatially connected curves, and detail is given on how it can be applied to map the length frequency histograms. At each sample location, a fish length frequency histogram is given as a vector of non-independent values. The histogram is first modelled as a polynomial expansion on the basis of orthogonal polynomials. Then, the polynomial coefficients are mapped by co-kriging, after fitting a model of co-regionalization. The length frequency map is finally derived by linearly combining maps of polynomial coefficients. An estimation variance associated with the map is also derived. Maps of anchovy length distributions are produced by applying the method to midwater trawl length data from the PELGAS acoustic surveys in the Bay of Biscay. This novel approach extends the application of kriging techniques to curves or functions, opening new perspectives for mapping more complex information than just the values of fish density.

scholarly journals Comparing the modelled and measured target-strength variability of walleye pollock, Theragra chalcogramma

2004 ◽  
Vol 61 (3) ◽  
pp. 363-377 ◽  
Author(s):  
Elliott L. Hazen ◽  
John K. Horne
Keyword(s):  
Ex Situ ◽  
Target Strength ◽  
Physical Factors ◽  
Fish Length ◽  
Acoustic Frequency ◽  
Backscatter Intensity ◽  
Model Predictions ◽  
Strength Variability ◽  
Boyle’S Law ◽  
Insight Into

Abstract Many biological and physical factors potentially affect target strength. While these sources have been identified, few studies have compared the relative effects of individual factors. Modelled and measured target strengths in non-dimensional metrics were used to compare and rank the effects of fish length, tilt, depth, and acoustic frequency on backscatter intensity. Ex situ measurements of target strength were used to examine the effects of tilt and depth and then compared to backscatter model predictions. Swimbladder volume reduction due to increasing pressure at depth was modelled using Boyle's law and by varying the ratio of dorsal to lateral compression. We found that length has the largest effect on the modelled and measured backscatter intensity, followed by tilt, frequency, and depth. Including tilt distributions in backscatter estimates improved the match between empirical target-strength measures and model predictions. Non-dimensional influence ratios provide insight into the sources and magnitudes of the backscatter variability.

Estimation of Fish Length from Acoustic Target Strengths

1987 ◽  
Vol 44 (10) ◽  
pp. 1782-1785 ◽  
Author(s):  
U. Buerkle
Keyword(s):  
Gadus Morhua ◽  
Statistical Significance ◽  
Orientation Distribution ◽  
Target Strength ◽  
Fish Length ◽  
Fish Sample ◽  
Length Frequency ◽  
Frequency Structure ◽  
Acoustic Target

I show that fish length distributions calculated from acoustic target strengths of cod (Gadus morhua) are in error when target strength–length relationships are used that do not account for the orientation distribution of the fish. The magnitude and statistical significance of the errors vary with the length frequency structure of the fish sample and are thought to be large enough to question the value of acoustically determined lengths in fish surveys if corrections for fish orientation are not applied.

scholarly journals The Amphipoda collected by the “Huxley” from the North Side of the Bay of Biscay in August, 1906

1911 ◽  
Vol 9 (2) ◽  
pp. 199-227 ◽  
Author(s):  
E. W. Sexton
Keyword(s):  
Geographical Range ◽  
Bay Of Biscay ◽  
The North ◽  
North Side ◽  
First Time

The Amphipoda dealt with in this paper were collected in August, 1906, by Dr. Allen, to whom I am indebted for the opportunity of examining them.The collection contained thirty-five species (belonging to twenty families), of which one only, Tryphosites alleni, is new to science. Five others, Stenothoe richardi, Syrrhoites walkeri, Syrrhoe affinis, Eusirus biscayensis, and Rhachotropis rostrata, are recorded for the first time since their original discovery. The geographical range of five species has been considerably extended, viz. Syrrhoe affinis, Tmetonyx similis, Sympleustes glaber, Epimeria parasitica, and Laetmatophihis tuberculatus; the four last forms have not been hitherto recorded with certainty south of Norway.

On Representing the Length Dependence of Acoustic Target Strengths of Fish

1979 ◽  
Vol 36 (12) ◽  
pp. 1490-1496 ◽  
Author(s):  
Kenneth G. Foote
Keyword(s):  
Analysis Of Covariance ◽  
Target Strength ◽  
Fish Length ◽  
Length Dependence ◽  
Dorsal Aspect ◽  
Significance Levels ◽  
Acoustic Target ◽  
Representation Method ◽  
Strength Functions ◽  
Linear Regressions

The problem of representing the length dependence of acoustic target strengths of fish is addressed by studying the legitimacy of merging target strengths that are inhomogeneous in species or frequency. The target strengths are of two kinds: maximum and averaged dorsal aspect target strengths, which are derived from measurements of gadoid target strength functions of three species at two ultrasonic frequencies. The target strengths are expressed variously according to unnormalized, wavelength-normalized and length-normalized schemes. Overall coincidences and coincidences of slopes among simple linear regressions of target strength on fish length, when segregated by target strength type and manner of representation, are investigated through analysis of covariance. Examination of computed significance levels demonstrates that merging of target strengths in species or frequency is generally unjustified and that no one representation method is superior to another in facilitating the merging of such data. The unnormalized representation is to be preferred when merging is justified because of its simplicity and avoidance of the frequency bias inherent in the normalized representations. The hypothesis of scaling of target strengths is refuted. Key words: target strength, regression, covariance analysis, fish abundance estimation

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