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The chemical ecology and antibacterial activity of the brown alga Halidrys siliquosa and other Scottish seaweedsRuchonnet, Diane Astrid January 2007 (has links)
In regard to the more and more restrictive legislations on the use of organotins in antifouling coatings the need for the development of 'environmentally friendly' antifouling formulations becomes urgent. This study was initiated by the screening of the antifouling activity of Scottish algae against marine fouling bacteria aI;ld was followed by an examination ofthe chemical ecology ofthe brown alga Halidrys siliquosa. Of eleven algal species tested, eight exhibited good antifouling activity, confirming marine algae as a potential source for the development ofnovel antifouling formulations. H. siliquosa crude extracts tested at concentrations equivalent to whole algal tissue inhibited bacterial growth, with bacteria isolated from the surface orH. siliquosa being less sensitive to the extracts compared to bacteria isolated from stones and open seawater. This suggested for the first time that bacteria associated with the surface of the seaweed had evolved some kind of resistance to the plant antimicrobial activity. Characterisation of the active components using NMR spectroscopy showed the activity to be largely associated with the presence of polyunsaturated fatty acids (PUFAs). Examination of purified fractions using GCIMS allowed identification and quantification of PUFAs 18:2, 18:4, 20:4 and 20:5. A separate study, determining minimum inhibitory concentrations of 18:2 and 20:4 against marine fouling bacteria indicated that both acids were present in sufficient concentrations in the plant to inhibit bacterial growth. The presence of PUPAs on the surface of the seaweed could not be demonstrated using a surface dip technique; however, this technique was originally developed for the extraction of non-polar metabolites only. This study suggests that PUFAs produced by H. siliquosa are potentially able to regulate biofouling by means of disrupting the early stage of biofilm development, i.e. bacterial colonisation. However, to confirm this hypothesis, the presence of PUFAs on the surface of the plant' still needs to be demonstrated.
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Bioactive secondary metabolites from marine and under explored habitatsRateb, Mostafa Ezzat M. January 2011 (has links)
This thesis presents results obtained from the investigation of secondary metabolites through screening of marine organisms, marine-derived microbes, and microbes form under-explored habitats. The first part includes the isolation of eight cytotoxic diterpene derivatives of which four were new from the organic extract of the sponge <i>Spongionella </i>sp. obtained from the U.S. National Cancer Institute’s Open Repository Program, the isolation of three new antibacterial dibenzofuran derivatives and a known butyrolactone from ascomycete Super1F1-09 isolated from the Indo-Pacific sponge <i>Acanthella cavernosa. </i>An attempt to synthesize these compounds was conducted. This part also includes the isolation of five known pyrroloiminoquinone alkaloids, from the Fijian sponge <i>Zyzzya</i> sp., which showed potent antiprotozoal activity. The second part comprises the use of OSMAC approach for the isolation of four new ansamycin-type polyketides, three new macrolactones and one known siderophore from <i>Streptomyces </i>strain C34 isolated from Atacama Desert, Chile. These compounds showed good antibacterial activity with one of the ansamycins showed pronounced antibacterial activity against a panel of clinical isolates of methicillin-sensitive as well as methicillin-resistant <i>S. aureus</i> (MRSA). This part also contains the use of microbial co-culture for the induction of secondary metabolites. It comprises the isolation of ten antiprotozoal fungal metabolites, of which one was new, from <i>Aspergillus fumigatus </i>when co-cultured with the novel strain <i>Streptomyces </i>C2 isolated from Atacama Desert. In conclusion, natural products from diverse sources proved to be the major resource of drug discovery. This thesis describes the isolation and structural characterisation of 35 compounds, 15 of which were new. Extremophiles proved to be a good source for new secondary metabolites.
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USW area analogs / Undersea warfare area analogsEverett, Keith R. 06 1900 (has links)
The purpose of this project is to investigate the feasibility of and methodology for the development of a set of environmental analogs of operational Undersea Warfare (USW) areas within fleet training areas. It is primarily a discussion of the identification of parameters that characterize the tactical USW environment, prioritization of these parameters, identification of existing databases that contain these parameters and an outline of the processes required to extract the desired data from the databases. An example of two operational areas with probable analogous training areas is discussed in terms of the methodology proposed. Among the environmental parameters considered are: bathymetry, sediment type, sound velocity profiles, acoustic response of the environment across a broad frequency spectrum (for both active and passive sonar), ambient noise, shipping density, bioluminescent properties, evaporation duct height, atmospheric surface duct height and gravitational anomalies. The project focus is primarily on acoustic oceanographic features but non-acoustic and atmospheric features are considered. There is an expectation that this project is the starting point for further research, software product development, data extraction, analog identification and promulgation of a tailored product to the fleet. The ultimate goal is to train for USW across the fleet in areas as much like the areas the Navy fights in as possible.
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Diagnostic indicators for shipboard mechanical systems using non-intrusive load monitoringMcKay, Thomas Duncan 06 1900 (has links)
CIVINS / This thesis examines the use of Non-intrusive Load Monitoring (NILM) in auxiliary shipboard systems, such as a low pressure air system, to determine the state of equipment in larger connected systems, such as the main propulsion engines. Using data collected on previously installed NILM's at the Naval Surface Warfare Center, Philadelphia DDG-51 Land Based Engineering Site (LBES), major event changes were analyzed and diagnosed using power data collected from the in-service low pressure air compressor (LPAC) and the in-service fuel oil pump. Events investigated include main propulsion engine starts and loadings, gas turbine generators starts, major electrical load shifts, and leak insertions into the low pressure air system. An additional NILM was installed on the General Electric LM2500 Universal Engine Controller (UEC) in order to assist in the diagnosis of various state changes. The UEC provides the appropriate interfaces to monitor and control each LM2500 GTM. The UEC controls the application of starter air, ignition power, and fuel to the engine while also receiving feedback of engine parameters from sensors on the engine. Using the combined data received by the LPAC, fuel oil pump, and UEC, a diagnosis system is derived that can detect major events in the engineering plant described above. / CIVINS / US Navy (USN) author
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Overwintering ecology and ecophysiology of Neocalanus plumchrusCampbell, Robert William 10 May 2017 (has links)
Neocalanus plumchrus is the most common copepod in the Northeast Pacific, and as such
plays in important role in the ecosystems of that area. The bulk of N. plumchrus’ annual life
cycle is spent in a dormant overwintering state, and little is known of its ecology, behaviour,
or physiology during that period. The goal of this thesis is to describe the physiological
changes that occur during the overwintering period, and explain how they interact with the
physical environment to produce observed life history patterns.
Lipid stores in N. plumchrus were primarily wax esters, and were in highest abundance in
overwintering stage 5 copepodids. Consumption of wax ester stores began approximately
two months prior to moulting in situ. Rates of lipid use in the in situ population and a
number of laboratory incubations ranged from 0.3 - 1% d⁻¹ , with 22 - 60% of total wax ester
reserves used prior to moulting, presumably to fuel gonadogenesis. Concurrent
measurements of protein content and glutamate dehydrogenase activity (an enzyme involved
in protein catabolism) did not show any significant protein use during overwintering.
Incubation experiments suggest that N. plumchrus has some concept of the time of year (i.e. an endogenous clock), but the use of external cues cannot be ruled out.
It is often assumed that the abundant lipids found in calanoid copepods play some role in
buoyancy regulation. However, lipids are generally more compressible, and more thermally
expansive than seawater, which means that neutral buoyancy will be inherently unstable. A
simple model of mass density shows that (i) individuals will only be able to stay at depth if
they are able to diagnose where they are neutrally buoyant, and (ii) the buoyancy properties
of an individual are extremely sensitive to its chemical composition.
In the Strait of Georgia, depth-specific measurements of abundance showed a shift towards
deeper depth distributions over the course of the overwintering period. Model results suggest
that lipid use could be responsible for those changes, though deep water renewal events that
occur regularly in the Strait of Georgia in winter may also have been partially responsible. / Graduate
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A case study of explosive cyclogenesis in the eastern Pacific Ocean 14-17 December 1987.Curtis, Jan. January 1989 (has links)
Approved for Public release; distribution is unlimited / An explosive cyclogenesis event that occurred in the eastern
Pacific Ocean on 14-17 December 1987 is investigated using the
National Meteorological Center (NMC) final analyses and
Geostationary Operational Environmental Satellite (GOES) digital
imagery. Forecasts for this cyclone by the Navy Operational Global
Atmospheric Prediction System (NOGAPS 3.0) and NMC Nested Grid Mesh
(NGM) forecasts initialized at 12 UTC 14 December are also
evaluated. Quasi-Lagrangian budgets of mass and vorticity are
computed to determine the factors responsible for the development
of this intense cyclone.
The initial surface development occurs within a strong
baroclinic zone southeast of a significant short-wave trough aloft.
Rapid intensification is accompanied by large cyclonic vorticity
advection in the upper troposphere as the surface cyclone moves
under the divergent quadrant of a 250mb jet streak. A key element
in this development is the superposition between the pre-existing
surface low and upper level short-wave trough in a favorable weak
static stability environment. These observations support earlier
studies that upper level forcing acts as a critical catalyst in
initiating eastern ocean explosive development. / http://archive.org/details/casestudyofexplo00curt / Lieutenant Commander, United States Navy
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Anadromous Pike in the Baltic SeaEngstedt, Olof January 2011 (has links)
The pike (Esox lucius) is a major predator and top-down regulator in the Baltic Sea where it exists in two sympatric forms. One spawn in streams and rivers and the other one spawn in the sea. During the last decades, the habitats for both of these forms have developed in a negative way. In some freshwater systems, up to 90 % of the water areas have disappeared, mainly through drainage and straightening of watercourses for agricultural purposes. In the sea, reproduction habitats decrease due to construction of harbours and human activities that create disturbances. The perhaps largest single factor negatively affecting recruitment of pike in the sea is the eutrophication. Bottoms are overgrown with filamentous algae and shallow bays are covered with dense Phragmites belts decreasing the habitats suitable for spawning. Further on, a predator on egg and fish larvae, the three-spined stickleback (Gasterosteus aculeatus) has increased in abundance. It is difficult to restore and enhance pike production in the sea and probably the only economically viable alternative is to make restorations in freshwater. However, there is a limited knowledge about the freshwater spawning pike in the Baltic Sea. Thus in this thesis I, together with my coauthors, set out with an aim to increase the knowledge base regarding anadromous pike behaviour. We found that pike of natal freshwater origin were common in the Baltic Sea. Through Sr:Ca studies in otoliths, about 45 % of the pike were interpreted to be of freshwater origin. The majority of the pike had emigrated out of freshwater at a length below 6 cm. These results indicate that freshwater recruitment is successful, contrasting the vast areas available for spawning in the sea. This creates incitements that restoration measures in these watercourses could have a significant effect on the pike population in the Baltic Sea. Further, in four streams running out in the Baltic Sea, more than three thousand pike were marked to study spawning migration. About 30-40 % returned to the same river the subsequent year. Most of the pike used the lower parts of the stream for spawning. The homing of pike to a watercourse indicate that freshwater pike in the Baltic Sea consist of specific populations and this is crucial information when taking decisions on fish restoration measures. Three wetlands adjacent to streams were restored for pike production. The most successful restoration involved minimal digging, with flooded grasslands providing optimal conditions for spawning. The first spawning season after restoration increased the pike production hundredfold. In conclusion, the anadromous pike are numerous in the Baltic Sea. To compensate for the decline in pike populations in the sea, “pike-factories” created along the coastline are probably the most justifiable option.
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Seaweed biodiversity around the Antarctic Convergence in the South AtlanticMystikou, Alexandra January 2015 (has links)
This study focuses on the seaweed biodiversity around the Antarctic Convergence in the South Atlantic. It integrates field work in the Falkland Islands and surrounding regions with algal culturing, molecular techniques, microscopy and morphological identification. Chapter 2 explores the diversity of seaweeds of the south-western Antarctic Peninsula which is poorly studied, contrasting with the substantial knowledge available for the northern parts of the Peninsula. A baseline seaweed species checklist for the southern Adelaide Island and northern Marguerite Bay region is presented here, combining data obtained during a small number of surveys in 1973-5 and a six week intensive diving-based field campaign in 2010-2011. Subantarctic and Antarctic regions remain little studied in their seaweed diversity. Chapter 3 is based upon field collections in the early 1970s and 2007-2013. It is supported by sequencing COI and reports new records of several macroalgal species and an oomycete. Chapter 4 revisits the enigmatic Subantarctic brown alga Cladochroa chnoosporiformis, which had been collected only on one occasion by Carl Skottsberg in 1907 from Port Philomel, West Falkland, resulting in its formal taxonomic description. Within the framework of this study, Cladochroa was rediscovered after 106 years at its type locality, confirming its existence and morphological features as described by Skottsberg. The recollection enabled molecular studies of its phylogenetic placement by DNA sequencing, suggesting that C. chnoosporiformis is conspecific with Utriculidium durvillei. In Chapter 5, DNA barcoding was applied to both seaweed tissue samples taken while preparing herbarium specimens during 2 expeditions to the Falkland Islands, and to live macroalgal isolates obtained from substratum samples using the Germling Emergence Method. In several cases, this enabled detection of previously unsequenced or undescribed taxa, respectively. The potential and challenges of applying DNA barcoding for cataloguing the biodiversity of remote bioregions such as the Falklands are discussed.
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A rational approach to the design of propulsors behind axisymmetric bodiesGüner, Mesut January 1994 (has links)
In the context of "Lifting Line Methodology", this thesis presents a rational approach to Marine Screw Propeller design and its applications in combination with a "Stator" device for further performance improvement. The rational nature of the approach is relative to the Classical Lifting Line procedure and this is claimed by more realistic representation of the propeller slipstream tube which contracts in radial direction along the tube at downstream. Therefore, in accordance with the Lifting Line Methodology, the design procedure presented in this thesis involves the representation of the slipstream shape by a trailing vortex system. The deformation of this system is considered by means of the so-called "Free Slipstream Analysis Method" in which the slipstream tube is allowed to deform and to align with the direction of local velocity which is the sum of the inflow velocity and induced velocities due ,to the trailing vortices. This deformation is neglected in the Classical Lifting Lin~ approach. The necessary flow field data or the wake for the design is predicted by using a three-dimensional "Panel Method" for the outer potential flow, whilst a "Thin Shear Layer Method" is used for the inner boundary layer flow. The theoretical procedures in both methods neglect the effect of the free surface and therefore the implemented software for the flow prediction caters only for deeply submerged bodies. However, the overall design software is general and applicable to surface ships with an external feedback on the wake. Since the realistic information on the slipstream shape is one of the key parameter in the design of performance improvement devices, the proposed design methodology has been combined with a stator device behind the propeller and the hydrodynamic performance of the combined system has been analysed. The design analysis involved the torque balancing characteristics of the system and the effects of systematic variations of the key design parameters on the performance of torpedo shape bodies and surface ships at varying loading conditions. The ·overall conclusions from the thesis indicate that a more realistic representation of the slipstream shape presents a higher efficiency in comparison to the regular slipstream shape assumption, in particular for heavily loaded propellers. Moreover, this representation is essential for sound design of the stator devices as it will determine the radius of the stator. From the investigation on the stator it was found that the undesirable effect of the unbalanced propeller torque can be avoided by the stator. The efficiency of the system will increase with the increase in the number of stator blades and the distance between the stator and the propeller over a practical range of the design parameters. It is believed that the procedure and software tool provided in this thesis could provide the designer with capability for more sound propeller and the stator design for, partly, surface ships and for submerged ships in particular torpedos, Autonomous Underwater Vehicles (AUV) and submarines. Although the improvement gained by the present procedure will be accompanied by an increase in computer time, this is not expected to be a major problem considering the enormous power of existing computers. In fact, this has been the major source of encouragement for the recommendation in this thesis to improve the present procedure by using the "Lifting Surface Methodology" as the natural extension of the Lifting Line Methodology.
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The use of image analysis techniques to characterise mid-ocean ridges from multibeam and sidescan sonar dataKeeton, Jane A. January 1994 (has links)
No description available.
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