Protocols for calibrating multibeam sonar

Author Posting. © Acoustical Society of America, 2005. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Acoustical Society of America 117 (2005): 2013-2027, doi:10.1121/1.1869073.Development of protocols for calibrating multibeam sonar by means of the standard-target method is documented. Particular systems used in the development work included three that provide the water-column signals, namely the SIMRAD SM2000/90- and 200-kHz sonars and RESON SeaBat 8101 sonar, with operating frequency of 240 kHz. Two facilities were instrumented specifically for the work: a sea well at the Woods Hole Oceanographic Institution and a large, indoor freshwater tank at the University of New Hampshire. Methods for measuring the transfer characteristics of each sonar, with transducers attached, are described and illustrated with measurement results. The principal results, however, are the protocols themselves. These are elaborated for positioning the target, choosing the receiver gain function, quantifying the system stability, mapping the directionality in the plane of the receiving array and in the plane normal to the central axis, measuring the directionality of individual beams, and measuring the nearfield response. General preparations for calibrating multibeam sonars and a method for measuring the receiver response electronically are outlined. Advantages of multibeam sonar calibration and outstanding problems, such as that of validation of the performance of multibeam sonars as configured for use, are mentioned.Support by the National Science Foundation through Award No. OCE-0002664, NOAA through Grant No. NA97OG0241, and the Cooperative Institute for Climate and Ocean Research (CICOR) through NOAA Contract No. NA17RJ1223 is acknowledged

Increasing Shipping in the Arctic and Local Communities’ Engagement : A Case from Longyearbyen on Svalbard

publishedVersio

Inducible cAMP Early Repressor (ICER) and Brain Functions

The inducible cAMP early repressor (ICER) is an endogenous repressor of cAMP-responsive element (CRE)-mediated gene transcription and belongs to the CRE-binding protein (CREB)/CRE modulator (CREM)/activating transcription factor 1 (ATF-1) gene family. ICER plays an important role in regulating the neuroendocrine system and the circadian rhythm. Other aspects of ICER function have recently attracted heightened attention. Being a natural inducible CREB antagonist, and more broadly, an inducible repressor of CRE-mediated gene transcription, ICER regulates long-lasting plastic changes that occur in the brain in response to incoming stimulation. This review will bring together data on ICER and its functions in the brain, with a special emphasis on recent findings highlighting the involvement of ICER in the regulation of long-term plasticity underlying learning and memory

Pesca do apaiari, Astronotus ocellatus (Agassiz, 1831), e perfil socioeconômico dos pescadores artesanais de uma região da Amazônia brasileira

The artisanal fishery is an important economic and subsistence activity among traditional populations in the Amazon Region. Therefore, the aim of this study was to characterize the fishery of apaiari, Astronotus ocellatus (Agassiz, 1831), and to present a socioeconomic profile of artisanal fishermen in the region lakes of Pracuúba, Amapá, Brazil. From May to August 2011 interviews were conducted using standardized forms with fishermen selected by "snowball" method and aged above 18 years old. A total of 68 fishing workers were interviewed, of which 55 were men and 13 women. It was possible to observe that fishing workers have a wide knowledge of fishery in the Region, including apaiari fishery, and that social and economic lives of the Pracuúba population depend totally of the artisanal fishery

Joint Russian-Norwegian selectivity experiments on cod (Gadus morhua L.) in the Barent Sea, 1995

With reference to point 4.3.2 in the protocol from the 23rd Session of the Mixed Norwegian- Russian Fisheries Commission, the parties agreed that necessary testing of sorting grids systems had to be performed during 1995 in order to enable the Fisheries Comrnission to reach a decision on the introduction of grid systems in the trawl fishery for cod in the Barents Sea. During the period 15-27 September 1995, joint Russian-Norwegian selectivity experiments with sorting grid systems were carried out in the Barents Sea on board the Russian vessel "Bizon" and the Norwegian vessel "Anny Kræmer". Two different grid systems were used, both with an inter-bar distance of 55 mm. The Norwegian vessel used predominantly the 4.5 m semi-rigid "Sort-X" system, while the Russian vessel used a 1.5 m single-grid system. In a few tows the Norwegian vessel used a single-grid system mounted in a two-panel Alfredo-type trawl. The experiment were divided into four periods. By assistance from the Norwegian vessel during the first period, the Russian trawl was observed by an underwater vehicle carrying video camera. The single-grid system appeared to perform as anticipated. Underwater observations of the singlegrid system in the Norwegian trawl revealed poor performance, and it was reinstalled to give a better performance. Comparative fishing trials in the second period with covers and blinders gave almost similar 50% retention values for "Sort-X" used in the Norwegian trawl and the Russian single-grid system in the russian trawl, with L50 of 50.3 and 49.7 cm, respectively. The "Sort-X" system gave a somewhat sharper selection, with a selection range of 11 cm compared to 15 cm for the singlegrid system. Both systems had a very good release of small fish; with an escape rate for fish smaller than 42 cm of 93-94% and of fish smaller than 47 cm of 88-89%. During the third period, single-grid systems were used on board both vessels. This system worked as before for the Russian trawl, but did not work properly with the Norwegian Alfredo-type trawl. Although a good performance during UTV-observation, the selectivity experiments revealed that the single grid in the Norwegian trawl had a low angle of attack, and that far from all fish were brought into contact with the grid. During the fourth and perhaps the most important stage of the experiments, the trawls were rigged as during commercial fishing, with a single-grid system and a 135 mm codend in the Russian trawl, and the "Sort-X" system and a 135 mm twin-codend in the Norwegian Alfredo-type trawl. The size distribution from the five parallel tows were not significantly different. Analysis of data from hauls with and without blinder revealed a slight codend selection in the Russian trawl aft of the single-grid system and minor or no codend size selection aft of the "Sort-X" system. The two grid-systems tested during these experiments have both their benefits and drawbacks regarding selectivity, handling and expenditure aspects. The grid systems as used in the respective trawls with ordinary codends give a close to similar selectivity, and will undoubtedly improve the overall size selectivity of bottom trawls.NORSK SAMMENDRAG:På oppfordring fra Den blandete norsk-russiske fiskerikommisjon (sesjon 23) ble det i september 1995 utført sammenlignende forsøk med to ristsorteringssystemer i torsketrål, det norske "Sort-X"-systemet og det russiske sorteringssystemet med enkel rist. Feltforsøkene ble utført ombord i MRr "Anny Kræmer" og MITr "Bizon" på kysten av Øst-Finnmark og ved Bjørnøya. Resultatene viser at det norske sorteringssystemet isolert sett ga litt bedre seleksjon enn det russiske. Når sorteringssystemene ble brukt som under kommersielt fiske uten noen form for dekknett, ga norsk og russisk trål tilnærmet lik lengdefordeling av fisk

Data for: Common and Fundamental Risk Factors in Shareholder Returns of Norwegian Salmon Producing Companies

The data set contains the time-series for the variables used in the empirical models in the paper

Shifting sentiments in firm investment: an application to the oil industry

Recent developments in the oil and gas industry suggest that investment behaviour is not necessarily changeless over time. We propose a micro-econometric procedure to investigate the stability of investment behaviour at the firm level. Applying system Generalized Method of Moments (GMM) on a panel data set for 253 oil and gas companies over 14 years, we estimate accelerator models of investment with error-correction. Robust econometric evidence indicates a structural break in oil and gas investment in 1998. The process of capital formation over the last few years is more flexible than before, with significant and material changes in the role of explanatory factors like cash flow and uncertainty.