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1
PANZERI, STEFANIA. « Le inchieste sui sinistri marittimi nel quadro comunitario ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2011. http://hdl.handle.net/10281/19840.
Texte intégralRésumé :
L’istituto delle inchieste sui sinistri ed incidenti marittimi, nella sua dimensione storica e giuridica, si colloca, fin dai suoi albori, in un’ottica squisitamente pubblicistica che, partendo da un approccio tipicamente security focused con funzioni puramente repressive, nel corso del tempo ha visto accentuarsi le finalità di tipo preventivo, safety focused. Negli ultimi anni, peraltro, la combinazione dei concetti di safety e di security ha contribuito alla creazione di un ulteriore nozione, allargata, di “sicurezza globale”, finalizzata al perseguimento della sicurezza della navigazione attraverso la realizzazione di uno sviluppo sostenibile basato sullo studio dell’ambiente e dell’uomo e non più verso della sola macchina-nave. In quest’ottica, l’interesse del legislatore – internazionale, comunitario e nazionale – è andato ad incentrarsi sul c.d. human factor, quale elemento fondamentale e prioritario di analisi in grado di offrire una efficace azione preventiva anche rispetto alle attività, considerate di per sé lecite, che abbiano superato il limite della accettabilità sotto il profilo umano ed ambientale. Con il codice IMO e la Direttiva 2009/18/CE, l’azione investigativa si traduce in un approccio il più possibile sistematico in grado di offrire agli investigatori uno strumento di valutazione e di rapportazione sempre più preciso e capace di garantire l’applicazione, di misure sempre più puntuali ed efficaci per migliorare la sicurezza marittima, impedendo così il ripetersi dei sinistri e degli incidenti (e la correlata perdita di vite umane, delle navi, nonché le conseguenze, spesso devastanti, di carattere ambientale).
Il costante raffronto tra la normativa internazionale, comunitaria e nazionale è finalizzato all’analisi delle criticità che inevitabilmente si manifestano in presenza di norme stratificate, pluriordinamentali e pluridisciplinari, con l’obiettivo di ottimizzare la conduzione delle inchieste in un settore, quale quello marittimo, fortemente globalizzato e proiettato in un’esasperata corsa tipica di alcune forme di competitività.
***
A broad, comparatistic analysis of marine casualty and incident investigation instruments (IMO code, 2009/18/EC Directive, national laws) provided to offer a standard approach with the sole purpose of correctly identifying the contributing factors leading to casualties and incidents. The aim is to provide remedial action and to improve safety in the shipping industry and thereby reduce environmental damage, identifying critical issues, practical and legal problems (such as requirements of the investigative body, that must be separated and independent of any other form of investigation, including investigations for action in civil, criminal and administrative proceedings; obtaining evidence from seafarers, witnesses and other parties involved; confidentiality of information; jurisdictional and other procedural differences between States) .
Marine casualties and incidents investigations are set out, in their historical and legal dimension, from their very beginnings, in a typically publicistic approach with a purely repressive security-focused perspective; over time they have experienced widening purposes, safety-focused. In recent years, however, the combination of the concepts of safety and security has contributed to the creation of an additional term, enlarged, of "global safety", which pursues the safety of navigation through the realization of sustainable development focused on the environment and “man” and not on the single machine-ship. In this context, the aim of the governing body - international, EU and national - is to focus on the human factor as a key factor of analysis and to provide an effective preventive action, also in relation to activities, per se lawful, which have exceeded the limit of human and environmental acceptability.
2
Nordblom, Gustav, et Louise Laiberg. « Riskkommunikation genom flera kommunikationsvägar : En studie baserad på haveriutredningar ». Thesis, Linnéuniversitetet, Sjöfartshögskolan (SJÖ), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-68292.
Texte intégralRésumé :
Risk communication in a modern maritime environment is unmistakably important but how does it fare against today’s science? This study focuses on a small part of risk communication, namely the differences in using one mean of communication as opposed to multiple means of communication. What positive and negative sides are involved in exchanging information through only one mean of communication as opposed to giving and receiving the information through many? The method is a literature study and the material ten accident reports made by administrative authorities. The reports have been analyzed and compared to modern subject science literature. The result of the study favor multiple means of communication such as public address systems, signs, general alarm and through the crew. The different ways create a redundancy and succeeds better at reaching a diversity of people. The negative sides, including confusion caused by too much or deviating information, appears to historically have been exaggerated. This is probably due to a false belief that man behaves irrationally in a state of crisis. The risk communication of the future is as such thick in information and comes through multiple means of communication.
3
Soulsby, Shane Alexander, et David James Hopper. « Investigation into service strike incidents and root causes ». Thesis, University of Canterbury. Engineering Management, 2014. http://hdl.handle.net/10092/8934.
Texte intégralRésumé :
Currently McConnell Dowell Constructors Ltd. is involved in the horizontal rebuild of Christchurch as part of the SCIRT alliance. Part of installing new infrastructure is that work is commenced around existing and live services. During installation, live services are occasionally struck which have the potential to cause injury and/or death along with subsequent economic costs of having to repair the damaged services.
David Hopper and Shane Soulsby have investigated some of the root causes for service strikes to occur with a distinct focus on process, communication, culture and costs. From that, key findings have been established along with recommendations and an implementation plan in an effort to lower the number of service strikes on projects.
4
Stephenson, Peter Reynolds. « Structured investigation of digital incidents in complex computing environments ». Thesis, Oxford Brookes University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405872.
Texte intégral
5
Rogers, S. « Learning from the investigation of incidents in primary care ». Thesis, University College London (University of London), 2007. http://discovery.ucl.ac.uk/1444077/.
Texte intégralRésumé :
Accident investigation is widely used to learn from adverse events occurring in industry. The conclusions of such investigations are typically used to inform the design and function of socio-technical systems and organisational management. This tradition is less well developed in healthcare, though evidence is growing that similar approaches may be applicable. The first part of the thesis reports a systematic review and evaluation of methods for the investigation of incidents in healthcare with further work then conducted to pilot an approach in primary and community care settings. The second part of the thesis describes the application of the approach within the framework of a study designed to understand the problem of medication related admissions in older people. The research maps the epidemiology of the problem and then moves beyond it through depth investigations of individual cases. The methods selected have provided an opportunity to understand the immediate and the contributory causes of adverse medication related events in older people. More particularly, the approach provided a framework for understanding general practice as a whole system, where there are interactions between people, processes and policies that can bring untoward consequences. This level of understanding of general practice identifies broader themes that characterise the organisation of primary care and point to areas for development that could bring substantial benefits to patients in the care they receive.
6
Miller, James Alexander. « An investigation into the management of clinical incidents involving qualified nurses ». Thesis, University of Edinburgh, 2005. http://hdl.handle.net/1842/24980.
Texte intégralRésumé :
Background: The researcher’s interest in the emerging areas of clinical governance and risk management within the National Health Service (NHS) was the genesis of this study. A growing concern about the apparent exponential rise in the number of untoward clinical incidents, the lack of studies of such incidents involving nurses and the developing interest in the apportionment of blame, were the basis of this research study examining the management of untoward clinical incidents involving qualified nurses. Conclusions: A number of conclusions were drawn from the data using these principle sources. Throughout the study the policy framework changed, reflecting the dynamic nature of this matter within the NHS. 1. There was a perception among qualified nurses that senior nurses involved in the investigation of an incident sought to blame and punish a nurse for their role within an incident as opposed to reviewing systems and processes potentially contributing to an error. 2. Nurses attributed different approaches to different ‘types’ of nurse mangers. It was evident that such punitive approaches prevented nurses from reporting incidents for fear of the reprisals. Some nurses attempted to deflect blame away from themselves and to attribute it to organisational issues whilst others accepted blame as a result of their involvement in an incident. 3. A consistent finding was nurses reported a blame-free culture was neither realistic nor desirable but described a ‘just and fair’ culture as being more appropriate. Such a culture recognising that errors are part of everyday life and should be seen within this context whilst ensuring that patients remain protected by calling nurses to account for any actions which may be regarded as negligent. 4. It was regularly reported that the lessons learned from such incidents were not disseminated either within the managerial units or across the organisation as a whole. Maintaining confidentiality in relation to the nurses involved was cited as the main reason for this lack of sharing. 5. There is little evidence that the wider literature available in respect of error management has been incorporated into policy development. The pre-determined standards in relation to this area of corporate governance, although at an embryonic stage have attracted significant criticism. 6. The determination produced from Fatal Accident Inquiries (FAIs) highlight shortcomings and within systems and processes likely to have contributed to a death. Sheriffs’ have used the determinants to redress the balance of some of the very negative and unjustified reports in the media. There is little evidence that these determinations are used as learning opportunities.
7
Hagos, Selam. « Chemical Investigation of Bioactive Marine Extracts ». Scholar Commons, 2018. https://scholarcommons.usf.edu/etd/7301.
Texte intégralRésumé :
Natural products have been a fundamental source of medicinal scaffolds for decades; with sixty percent of marketed drugs. Many synthetic chemists are focused on synthesizing potent and nontoxic compounds for pharmaceutical targets, however, nature is still proving to be a source of new bioactive compounds. Produced by the host organism for defense, reproduction and communication, secondary metabolites also demonstrate promising bioactivity against human pathogens. Hence, natural product chemists continue their quest for new leads.
As a continuation of these efforts, this thesis attempts to explore fungi and sponges for new chemistry, and ultimately, new drug candidates. Antarctica is largely untapped; hence herein two Antarctic sponges were chemically investigated. This resulted in isolation and characterization of two metabolites. Concurrently, chemical investigation of fungus, from Floridian mangrove species, resulted in the isolation of two structurally diverse metabolites. Further, a dereplication process was applied to MPLC fractions, which lead to the identification of known metabolites and mycotoxins. This enabled prioritization of fractions for future studies.
8
Millard, Andrew David. « An investigation of cyanophages infecting marine Synechococcus ». Thesis, University of Warwick, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.415250.
Texte intégral
9
Park, Young Chul. « Chemical Investigation of Three Antarctic Marine Sponges ». Scholar Commons, 2004. https://scholarcommons.usf.edu/etd/1190.
Texte intégralRésumé :
This thesis describes the chemical investigation of three marine sponges from Antarctica and the total syntheses of natural products erebusinone (12) and its derivative, erebusinonamine (52). Investigation of the yellow Antarctic marine sponge Isodictya setifera resulted in the isolation of two secondary metabolites, purine analog (32) and 3-hydroxykynurenine (24). Chemical investigation of Isodictya setifera led to the isolation of six secondary metabolites which included 5-methyl-2-deoxycytidine (25), uridine (28), 2-deoxycytidine (31), homarine (37), hydroxyquinoline (33), 3-hydroxykynurenine (24). The latter two compounds were found to be intermediates of tryptophan catabolism in crustaceans. From the Antarctic marine sponge Isodictya antractica ceramide analog (39) was isolated and its chemical structure was assigned by a combination of spectroscopic and chemical analyses. Stereochemistry was determined by modified Mosher's method. Erebusinone (12), a yellow pigment isolated from the Antarctic marine sponge Isodictya erinacea has been implicated in molt inhibition and mortality against the Antarctic crustacean amphipod, Orchomene plebs, possibly serving as a precursor of a xanthurenic acid analog.
Thought to act as a 3-hydroxykynurenine 24 mimic, erebusinone (12) may be involved chemical defense. This appears to be the first example in the marine realm of an organism utilizing tryptophan catabolism to modulate molting as a defensive mechanism. To further investigate the bioactivity and ecological role of erebusinone (12), the synthesis of this pigment was carried out in an overall yield of 44% involving seven steps which were economical and convenient. Erebusinonamine (52) was also similarly synthesized in eight steps with an overall yield of 45%.
10
Littlejohn, Lexia M. « The impact of retreating sea ice on Arctic marine transport and development : an integrated risk and scenario-based approach to framing solutions for potential marine incidents / ». May be available electronically:, 2008. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
Texte intégral
11
Henderson, Holly Elizabeth. « An investigation into the epidemiological surveillance of inland water incidents in the United Kingdom ». Thesis, University of Birmingham, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419730.
Texte intégral
12
Mouw, Colleen Beckmann. « Bio-optical and remote sensing investigation of phytoplankton community size structure / ». View online ; access limited to URI, 2009. http://digitalcommons.uri.edu/dissertations/AAI3368002.
Texte intégral
13
Leach, Peter A. « Marine Geoarchaeological Investigation of Damariscotta River, Maine, USA ». Fogler Library, University of Maine, 2007. http://www.library.umaine.edu/theses/pdf/LeachPA2007.pdf.
Texte intégral
14
Eddies, Roderick David. « An investigation of seismic attenuation in marine sediments ». Thesis, University of Plymouth, 1994. http://hdl.handle.net/10026.1/2109.
Texte intégralRésumé :
There have been relatively few investigations into the attenuation properties of unconsolidated sediments using marine surface seismic data. Several methods of measuring attenuation were assessed for reliability in a noise-free case and with the addition of noise using a set of synthetically absorbed and dispersed wavelets. Wavelet modelling proved to be superior to the other techniques, followed by spectrum modelling and the spectral ratios method. Complex trace analysis using the analytical signal proved to be unreliable for non-sinusoidal wavelets, whilst the risetime method was found to be very susceptible to noise for practical purposes. Numerical modelling was carried out to assess the spectral effects of layering on a propagating pulse. The thin layer / peg-leg phenomenon has varying filtering effects on the propagating pulse. In particular, layers which are less than the "tuning thickness" of the propagating pulse have a low-pass effect. The quality factor, Q, was measured in two case studies. In the first, the mean Q was determined from wavelet and spectrum modelling and found to be 60 for fine sands and 47 for coarse sands in the 1 kHz to 3 kHz frequency band. In the second, Q was determined as 59 for poorly sorted sandy diamicts in the 100 Hz to 240 Hz frequency band. The close fit between synthesised spectra and wavelets and observed data showed that a constant- Q mechanism would account for the spectral changes between the seabed and the deeper target reflection events in the two case studies. The spectra of the target reflection events in both case studies were lacking in low frequencies which is likely to be due to low-pass filtering from composite reflection events due to thin bed layering. For practical purposes, the determination of Q from a mean normalised seismic trace yielded the same result as measuring a mean Q from individual traces. In a third case study, the seabed multiple was compared to the seabed reflection using wavelet and spectrum modelling. A lack of low frequencies in the seabed multiple showed that the seabed can act as a low-pass filter to an incident pulse. As the numerical methods rely on the seabed as having a white reflection and transmission response, the low-pass effect will result in erroneous estimates of the quality factor, Q.
15
Falkner, Kelly Kenison. « An investigation of the marine geochemistry of gold ». Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/52902.
Texte intégralRésumé :
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1989.Vita.
Includes bibliographical references (leaves 94-101).
by Kelly Kenison Falkner.
Ph.D.
16
Duerr, Phillip S. « Investigation of marine waterjet inlets during turning maneuvers ». Thesis, Florida Atlantic University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10095898.
Texte intégralRésumé :
Numerical simulations of waterjet inlets have been conducted in order to understand inlet performance during ship turning maneuvers. During turning maneuvers waterjet systems may experience low efficiency, cavitation, vibration, and noise. This study found that during turns less energy arrived at the waterjet pump relative to operating straight ahead, and that the flow field at the entrance of the waterjet pump exhibited a region of both low pressure and low axial velocity. The primary reason for the change in pump inflow uniformity is due to a streamwise vortex. In oblique inflow the hull boundary layer separates when entering the inlet and wraps up forming the streamwise vortex. These changes in pump inflow during turning maneuvers will result in increased unsteady loading of the pump rotor and early onset of pump rotor cavitation.
Simulations covered drift angles from 0° to 30°, pump velocities relative to free stream speed of 0.6 to 1.0 for inlet geometries with ramp angles of 25° and 30° with inlet-hull fairing radii relative to pump diameter of 0.1 to 0.2. The following observations were made: 1) the onset of the streamwise vortex occurred between drift angles of 5° and 10°; 2) increasing drift angle increased the strength of the streamwise vortex and lowered the energy of the flow entering the pump; 3) increasing the flow rate through the waterjet system increased the strength of the streamwise vortex; 4) increasing ramp angle tended to increase the strength of the streamwise vortex; and 5) increasing the fillet radius decreases the strength of the streamwise vortex.
Simulations of steady ahead operation of the waterjet propelled R.V. Athena were also conducted for Froude numbers of 0.34 to 0.84. From these simulations it was found that the pump inflow can be effectively approximated at a new ship speed from a known ship speed by scaling only the mean component of the axial velocity by the relative change in waterjet flow rate. Additionally, waterjet pump operating point and rotor blade inflow angles were found to independent of ship speed.
17
Pengprecha, Paramee. « Investigation of arsenic behaviour in a marine environment ». Thesis, University of Aberdeen, 2001. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU143431.
Texte intégralRésumé :
The conversion of arsenic into organoarsenic compounds is affected by the action of organisms, particularly marine organisms. These arsenic species require a suitable technique to distinguish the species and quantify their abundance. The ICP-MS coupled to either HPLC or HG-CT are the most popular techniques for arsenic species could be separated, but the limit of detection (LOD) was not satisfactory for the concentration of arsenic in natural waters and the chloride interference in the marine samples was high. While the HG-CT-ICP-MS, the LOD was sufficient to detect very low concentrations of arsenic, particularly for methylated arsenic species, and there was no chloride interference, however the inorganic arsenic in the reagents was high and only the reducible arsenic species could be detected. The transformation of organoarsenic compounds, specifically the conversion of arsenosugars by micro-organisms in sediment, was studied by analysing porewater from decaying seaweed in a mesocosm experiment. Arsenosugars degraded to DMAE further to DMAA to MMAA and finally to As(V) and As(III), but not as previously proposed to AsB, AsC and TMAO. Arsenic was released by the dissolution of manganese and iron clay particles in a pristine area but much more by anaerobic degradation in an industrial area. Arsenic was removed from the water phase to the sediment by precipitation, particularly with manganese at the surface sediment only in the pristine area but with iron in the industrial area.
18
Zoller, Carolin [Verfasser], et S. [Akademischer Betreuer] Grohmann. « Experimental Investigation and Modelling of Incidents in Liquid Helium Cryostats / Carolin Zoller ; Betreuer : S. Grohmann ». Karlsruhe : KIT-Bibliothek, 2018. http://d-nb.info/1160303665/34.
Texte intégral
19
Segraves, Nathaniel Lee. « Chemical investigation of biologically active alkaloids from marine sponges / ». Diss., Digital Dissertations Database. Restricted to UC campuses, 2005. http://uclibs.org/PID/11984.
Texte intégral
20
Nilsson, Anders. « Investigation in how to design a marine current turbine ». Thesis, Uppsala universitet, Elektricitetslära, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-135703.
Texte intégral
21
Allen, M. M. « An investigation of sampling techniques within marine fisheries discards ». Thesis, Queen's University Belfast, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.516947.
Texte intégral
22
Louvros, Dimitrios. « Investigation of the reliability deterioration of ageing marine structures ». Thesis, Cranfield University, 2013. http://dspace.lib.cranfield.ac.uk/handle/1826/8470.
Texte intégralRésumé :
In the present work, an investigation of the fatigue life benefits emerging from
fillet weld geometries optimization has been carried out.
At first, an introduction to ageing mechanisms, corrosion and especially fatigue,
acting on operating marine structures has been made. Residual stresses at
weld toes, stress modes, and types, geometrical factors (weld angle, toe radius,
leg length), welding techniques selected, post-welding treatment and plate‟s
material are some of the principal factors affecting the fatigue life of a fillet weld
joint.
Especially, the accuracy of various approaches in fatigue life estimation of
specific geometries under pre-set types and levels of stress is studied. It is
evident so far that even the notch stress concept is the most accurate method
based on S-N curves, the Fracture Mechanics approach can offer more
accurate solutions of a crack development through the material. Towards this, a
literature review on crack evolution aspects in welded and non-welded plates
under bending and tension was performed; substantial parameters were
determined and finally implemented in the LEFM model which was used for the
simulation purposes of Chapter 6.
As far as the crack aspect ratio evolution is concerned, an extensive reference
is available in literature since many researchers have investigated its
contribution to the determination of geometrical paths, commonly known as
“Preferred Propagation Paths”. Their significance is related with our ability to
determine accurate SIF solutions leading to precise fatigue life estimations.
A typical fillet weld joint 2-D model has been developed in CAE Abaqus
software and a Finite Element Analysis of subject T-profile has been carried out.
Through this analysis, the fillet weld angle, the weld leg length, the weld toe
curvature radio ρ and the carrying load plate thickness are examined for their
impacts on the maximum surface stress. Finally, a number of stress mitigating
measures are proposed and their effects are analyzed.
Undoubtedly, the notch stress concept today is gradually gaining more and
more acceptance among other fatigue analysis practices, hence the need for an
estimation of the actual surface stresses along fillet weld toes, has become
imperative. Towards this, different 2-D geometries are tested against stress
concentration factors developed at weld toes, which are calculated on the basis
of maximum in-plane principal stresses over nominal stresses in mode I pure
bending and pure tension respectively. Moreover, validation with corresponding
results from literature is provided. Finally, three different concepts for reducing
the maximum surface stresses are presented. The first one proposes grinding
of the weld toe area and formulation of an artificial U-notch or a part- circular
profile. The second one applies to non-penetrating welds and assumes the
existence of a root gap of a specific geometry which is related to the fatigue life
and stress concentration factor of the fillet weld joint. Last but not least, the
relatively recent concept of the variable radius notch is discussed, even though
it is applicable mostly to notched bodies, not weld joints.
Afterwards, a Linear Elastic Fracture Mechanics analysis of reference 2D fillet
weld model is demonstrated. A number of geometrical parameters considered
at previous stage for their impact on surface Stress Concentration levels at the
weld toe region, have been correlated to fatigue life benefits in terms of
increased number of stress cycles till failure.
An extensive analysis of 9 different T-butt weld joint geometries has been
provided in order to investigate how positively a possible SCF reduction can
affect the fatigue life of a weld joint. Essential geometric variations (weld angle,
length, toe radius, root slot) were considered in the 2D model. All calculated
benefits both in pure bending and pure tension cases have been reported
accordingly.
Based on a linear interpolation of the points scatter (SCF, N-cycles) both in
banding and tension, it was observed that a surface stress mitigation of 1%
could lead to 1,33 up to 2,5% fatigue life benefit in the range of SCF=2 – 2,5. It
is evident so far that the geometrical optimization of a weld joint in respect of
notch stress mitigation can be a powerful tool both in shipbuilding and
maintenance practice in the future. However, technically wise their application
may incur high initial costs of improved tools of welding and post welding
treatment and robots even though it would consist a cost effective solution in a
medium/long term basis.
Finally, the above process is followed by a reliability analysis of the most critical
geometrical parameters affecting the fatigue life of a fillet weld joint. Reliability
assessment results concerning medium, high and low cycle fatigue are provided
and a comparative analysis of each factor‟s impact on fatigue life has been
carried out.
23
Nedrebø, Eirik Leikvoll. « Experimental Investigation of Marine Fouling on Piles in Currents ». Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for marin teknikk, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-26246.
Texte intégralRésumé :
Various effects of marine fouling on piles have been addressed through a literature study and an experimental investigation. The experimental investigation was conducted on circular cylinders in steady current at subcritical Reynolds numbers. Hard marine fouling was modeled on the surface of three different cylinder models using sand and gravel particles with relative roughnesses k/D = 0.01, 0.02 and 0.07. In addition, one cylinder model was kept smooth, while one cylinder model was covered with artificial fur to simulate soft marine fouling. The drag and the wake velocity were measured, and in addition a flow visualization was carried out. The cylinders had a free end and the tests were performed in a free surface flume tank.On the cylinders covered with artificial hard marine fouling, the mean drag was found to increase with increasing surface roughness. The mean drag of a cylinder covered by artificial soft marine fouling was almost three times the drag of a smooth cylinder with the same diameter. A cylinder with a diameter of 0.042 m covered with artificial soft marine fouling, was found to have approximately the same drag as a 0.10 m smooth cylinder.The streamwise velocity at points along the centerline of the wake was measured using the optical technique Laser Doppler Velocimetry (LDV). In the case of hard marine fouling, increasing surface roughness was found to increase the mean velocity near the cylinder, and to decrease the mean velocity further away from the cylinder. The results also indicated that increased surface roughness decreased the Reynolds number dependence of the wake closure length (the region where the mean velocity is negative).The presence of soft marine fouling was found to have a large impact on the mean velocity in the wake. Here, the wake closure length was found to be approximately 3.6-3.7 times longer than for a smooth cylinder.The flow visualization showed that the Strouhal number was reduced from approximately 0.19 to 0.16 when hard marine fouling was introduced. For soft marine fouling, the Strouhal number was approximately 0.11. The visualization also supported the findings from the LDV tests.It was concluded that marine fouling could have large consequences for both the forces on a circular cylinder and on the flow around it. The effects of soft marine fouling were found to be more significant than the effects of hard marine fouling for all parameters in the investigation.
24
Page, Catherine. « Investigation of the cytogenetics of marine and terrestrial gastropods ». Thesis, London Metropolitan University, 1985. http://repository.londonmet.ac.uk/3431/.
Texte intégralRésumé :
The investigation of the chromosomal variation in populations of the land snail Cepaea nemoralis (L.) marine snail Nucella lapillus (L.) is presented. The first study (Part 1) concerns the investigation of the karyotype of C. nemoralis in populations from a region of the Berkshire Downs (U.K.)in which there are marked area effects for both the visible and allozymic characters. The present investigation has shown that there are inter-populational differences in chromosome structure. The differences fall within the range found previously in several widespread populations in the British Isles, Northern Europe and America. There are no immediately obvious variations in chromosome structure associated with observable environmental variables. There are, however, marked non-random associations of karyomorphs within some of the "area effect populations". The implications of the distribution of the karyotypic variations between the populations are discussed. The second study (Part 11) concerns the identification of the chromosome pairs involved in the numerical (Robertsonian) and structural (inversion) polymorphisms of Nucella lapillus and the investigation of the two types of polymorphism in populations of low chromosome number. A new classification of the karyotype into five main groups A to E has been made. The chromosome pairs thought to contribute to the numerical polymorphism occur in groups A, B and C and the two inversion polymorphisms occur in groups A and C. The distribution of the two types of chromosomal polymorphism at Rottingdean, Sussex (U.K.) suggest that the inversion polymorphism from group C, and the numerical polymorphism, also from group C, occur independently of each other. The differences in the distribution of the two polymorphisms in the Rottingdean area and the differences in the distribution of the chromosome pairs involved in the numerical polymorphism in different populations are discussed.
25
Carr, Paul Gerard. « An Investigation of the Relationship between Personality Traits and Performance for Engineering and Architectural Professionals Providing Design Services to the Building Sector of the Construction Industry ». Diss., Virginia Tech, 2000. http://hdl.handle.net/10919/29710.
Texte intégralRésumé :
One of the prominent trends in business organizations today is the attention placed on individual personality traits to predict job performance. Distinct personality characteristics of members of various work groups must be carefully considered so that the assignment of individuals to work teams results in successful behaviors and performance improvements. The particular task assignment to various work groups, and thus assignments to individuals, will affect performance. It is critical that these individuals possess both the abilities and behavioral preferences to create conditions that promote the highest probability for success. Contingent variables will always be present in any decision-based action, particularly in complex situations, however, when an individual holds a native preference for a successful pattern of behaviors in a certain task's realm, higher overall organizational performance may be expected. As such, the current study investigates the impact of various personality traits and patterns on critical success behaviors in the Engineering and Architectural profession's project design services. The four project service categories measured in the Critical Success Factors Questionnaire are: Planning (Conceptual Design), Design (Contract Documents), Construction (Administration) and Firm Management duties. The measurement of the individual personalities is accomplished in this investigation through the Myers-Briggs Type Indicator ® (MBTI).. This psychometric instrument measures one's attitudes in dealing with the outside world, as well as one's preferences for data collection and decision making.
On an individual basis, it was predicted that persons with personalities whose preferences were towards openness to new ideas, and resistant to closure of the discovery process, would perform well on planning or conceptual design tasks. It was predicted that those with a preference towards compliance with rules, regulations and thorough adherence to established standards, would outperform on tasks of detailed design. The research work also offered a prediction of high performance from persons with a preference for innovative ideas and openness to alternatives in the administration of construction, and predicted a contrast with personalities that vary from this pattern.
Of the 85-person sample, it was found that those possessing a preference for Intuitive data collection (MBTI Dichotomy, N) and Perceiving structure, (MBTI Dichotomy, P), outperformed individuals with preferences for Sensing and Judging, (MBTI Dichotomies S and J), in both Planning and Construction Administration. However, professionals with a personality favoring Judging, outperformed in the duties associated with the Design Phase. Contrary to predictions, the decision processes captured in the Thinking/Feeling MBTI® dichotomy (MBTI, T/F) did not meditate the performance in any of the four service categories.
The results of the Research indicate a greater utility for personality measures as a diagnostic tool for team and individual performance interventions, rather than a tool for team selection or team-building. The implications of the results of this research, and recommendations for future investigations are discussed.Ph. D.
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Mair, Angus. « Investigation into a prominent 38 kHz scattering layer in the North Sea / ». St Andrews, 2008. http://hdl.handle.net/10023/490.
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Burton, Gareth C. « A review of the forensic engineering analysis employed in the investigation of fire and explosion related incidents ». Thesis, Ulster University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.403632.
Texte intégral
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Harpur, Amy. « A detailed investigation into occupant behaviours and influencing factors surrounding fatal dwelling fire incidents in Northern Ireland ». Thesis, Ulster University, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.625444.
Texte intégralRésumé :
More people die in dwelling fires than fires in any other location. Despite considerable efforts to prevent dwelling fire deaths they are still occurring. In 0 rder to investigate why people are still dying in dwelling fires detailed circumstances surrounding 129 fatal dwelling fires in Northern Ireland were investigated using data gleaned from coronial reports. Compared to their share in the underlying Northern Ireland population, males, the very young and elderly, smokers, problem drinkers, those that live alone and those with a pre-existing illness were found to be over-represented among dwelling fire fatalities. In-depth analysis of the circumstances surrounding very young fatalities indicated that fire-play, having a smoker in the householder, inadequate supervision and dismissive attitudes to fi re safety in the home. Further analysis of the elderly dwelling fire fatality group indicated that an age-related decline in health and mobility impairments played an important role in the fatalities. An additional analysis comparing the fatalities to those that survived the fatal fire incidents indicated that unlike fatalities, those that survived were rarely in close proximity to the seat of the fire when they became aware of the fire. A further important finding of this research was that there were health, social and welfare issues within the home environment of the fatalities that were fundamental to their demise. These often formed barriers to implementing fire safety strategies among those most at-risk. Over-coming these barriers through a multi-disciplinary and inter-agency approach may be the key to preventing more fire deaths. It is hoped that the findings of this research will inform community fire safety strategies in the future both in Northern Ireland and further afield.
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Id-Daoud, Ghezlane. « Investigation of the antifouling properties of extracts from marine microalgae ». Thesis, University of Portsmouth, 2015. https://researchportal.port.ac.uk/portal/en/theses/investigation-of-the-antifouling-properties-of-extracts-from-marine-microalgae(c1bf0945-cf62-4ace-aa8f-1a786a552671).html.
Texte intégralRésumé :
Biofouling, through undesirable colonisation of surfaces by marine organisms, is responsible for significant economic and environmental impacts that justify the use of antifouling (AF) coatings. Extracts from cultivable microalgae were investigated as a sustainable and eco-friendly source of AF compounds. A multi-functional bioassay was developed to test microalgal extracts against biofilm-forming bacteria and diatoms (behaviour, growth, adhesion, toxicity, species interactions). The AF activity of extracts from seven microalgae was investigated against microfoulers, macroalgae and barnacles, and, the impact of stresses was assessed. Inhibitory activities were recorded against a wide spectrum of organisms between 0.01 and 100 μg.mL-1, and complex doseresponses with stimulatory effects were highlighted. The AF activity was improved using competition and dark stress on marine microalgae, and was repressed using predation on freshwater species. Replicate experiments conducted using dark stress demonstrated the stability of stress responses, when comparing AF activity and metabolic profiles, for Cylindrotheca closterium and Thalassiosira pseudonana. These strains, which showed high biomass and extract yields (5%-10%), were further studied for fractionation and field-tests. Fractions of intermediate polarity from C. closterium demonstrated the most potential in the laboratory. In the field tests, Cc5 still showed moderate activity against early formation of algal slime in Portsmouth, and Cc6 reduced invertebrates’ settlement in Toulon. The microalgal culture-associated bacteria studied showed high diversity, microalgal proximity, and multifaceted chemical interactions. A comparative study showed that microalgal and bacterial extracts exhibited different patterns of AF activity and distinct chemical signatures, confirming the microalgal origin of extracts studied throughout. This work proposed a multi-functional AF screening of microalgal compounds for a better understanding of the mode of action, it demonstrated the tangible potential of microalgal extracts for AF applications, and it addressed the limits of an AF strategy based solely on chemical interactions - encouraging future use of combinatory approaches.
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Colwill, R. D. « Marine drag anchor behaviour-a centrifuge modelling and theoretical investigation ». Thesis, University of Manchester, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.508339.
Texte intégral
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Hudson, Cheryl. « A physiological and molecular investigation into the marine fungus Dendryphiella ». Thesis, University of Wolverhampton, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.418885.
Texte intégral
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Mann, Maryssa Gudrun Ailsa. « An investigation of the antimicrobial and antifouling properties of marine algal metabolites ». Thesis, Rhodes University, 2008. http://hdl.handle.net/10962/d1007465.
Texte intégralRésumé :
Prevention of the accumulation of undesirable biological material i.e. biofouling upon a solid surface requires the use of antifouling systems. The solid surface may be a contact lens, an off shore oil rig or a living organism. When chemicals are employed as a mechanism of defense against biofouling, the agents involved are known as antifouling agents. Marine algae must protect themselves from fouling organisms and it is thought that one of the mechanisms used by these organisms is the production of secondary metabolites with an array of biological activities. In vitro studies have shown numerous compounds isolated from marine algae to possess antibacterial, antifungal and antimacrofouling activity. The aim of this study was to evaluate the secondary metabolite extracts of selected Southern African marine macro-algae as a potential source of compounds that inhibit biofilm formation and that could be used as antifouling agents. In this project, marine macro-algae were collected from various sites along the South African coastline. Their extracts were screened for antimicrobial activity against four ubiquitous microorganisms, Staphylococcus aureus, Klebsiella pneumoniae, Mycobacterium aurm and Candida albicans. Results of screening assays guided the fractionation of two Rhodophyta, Plocamium corallorhiza and Laurencia flexuosa. The algae were fractionated using silica gel column chromatography and compounds were isolated by semi-preparative normal phase HPLC. Compound characterization was performed using UV, IR and advanced one- and two-dimensional NMR (¹H, ¹³C NMR, COSY, HSQC, HMBC and NOESY) spectroscopy and mass spectrometry. Ten halogenated monoterpenes including four members of the small class of halogenated monoterpene aldehydes were isolated from extracts of P. corallorhiza. The compounds isolated included the known compounds 3,4,6,7-tetrachloro-3,7-dimethyl-1-octene; 4,6-dibromo-1, 1-dichloro-3,7 -dimethyl-2E,7 octadiene; 4,8-d ibromo-1,1,7 -trichloro-3, 7-dimethyl-2,5Eoctadiene;1 ,4,8-tribromo-3, 7 -dichloro-3,7-dimethyl-1 E,5E-octadiene; 8-bremo-6, 7-dichloro-3,7-dimethyl-octa-2E,4E-dienal; 4-Bromo-8-chloro-3,7-dimethyl-octa-2E,6E-dienal; 4,6- Dibromo-3,7-dimethyl-octa-2E,7-dienal; 2,4-dichloro-1-(2-chlorovinyl)-1-methyl-5-methylidene-cyclohexane and two new metabolites 4,8-chloro-3,7-dimethyl-2Z,4,6Z-octatrien-1-al and Compound 3.47. Methodology was developed for the chemical derivatization and mass spectrometric analysis of the aldehydic compounds, The aldehyde trapping reagent 0-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride was used to derivatize the molecules, stabilizing them and allowing for their complete characterization. From Laurencia flexuosa a new cuparene sesquiterpene 4-bremo-2-(5-hydroxy-1,2,2- trimethylcyclopent-3-enyl)-5-methylphenol was isolated along with two geometric isomers of the vinyl acetylene bromofucin , An halogenated monoterpene 3S*,4R*-1-bromo-3,4,8-trichloro-9-dichloromethyl-1-E,5-E,7-Z-octatriene was also isolated but was suspected to be a contaminant and an investigation into its biological source revealed that it originated from Plocamium suhrii. A third alga, Martensia elegans was extracted based on published reports of antimicrobial compounds in related species. A new a-alkyl malate derivative was isolated and characterized. Selected compounds isolated during the course of the study were employed in preliminary assays that tested their ability to inhibit biofilm formation by Pseudomonas aeruginosa. The halogenated monoterpenes isolated from the Plocamium species were the only active compounds. 3S*,4R*-1-bromo-3,4,S-trichloro-g-dichloromethyl-1-E,5-E,7-octatriene from P. suhrii inhibited biofilm formation through antibacterial activity on planktonic cells but could not prevent biofilm formation when employed as a film on the surface of microtitre plate wells. 1,4,8-tribromo-3,7-dichloro-3,7-dimethyl-1E,5E-octadiene and 4,6-dibromo-1,1-dichloro-3,7-dimethyl-2E,7-octadiene inhibited biofilm formation when applied as a film to the microtitre plate wells but had no significant antibacterial activity. No potential antifouling agents were identified in this project but the antimicrobial activity exhibited by the crude algal extracts was highly encouraging and a number of new research areas have been identified.KMBT_363
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Teutsch, Ina. « Investigation of the Wake Flow behind a stepped circular Cylinder using Particle Image Velocimetry ». Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for marin teknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18572.
Texte intégralRésumé :
Subject of the present study was the investigation of the wake behind stepped circular cylinders. Experiments were performed using particle image velocimetry (PIV). Cylinder models with diameter ratios D/d=1, D/d=6/5 and D/d=2 were investigated at Reynolds numbers Re_{D}=2243.6, Re_{D}=12820.5 and Re_{D}=51282.1 with respect to the large diameter. Of main interest were the influences of step size and Reynolds number on the formation of vortex shedding cells. Mean flow characteristics and instantaneous captures of the flow field were analyzed in order to gain insight into vortex development in the wake. Spectral analysis was applied to obtain information on the number of forming vortex shedding cells.It was found that an increase in Re_D leads to a decrease in eddy formation length $L_f$. At the largest investigated Reynolds number, turbulence gained strong influence on the flow characteristics. An increase in stepsize leads to the development of a large and a small diameter wake with distinct eddy formation lengths L_{f,L} and L_{f,S}.Due to a mismatch in vortex shedding frequencies in the two wakes, vortices that come out of phase connect to subsequent vortices on the same side of the step. This occurs more frequently for a higher diameter ratio.Several vortex shedding cells were found in the wake of the step cylinders, their number increasing with the step size and differing for different Reynolds numbers.The wake behind step cylinders was discovered to be strongly three-dimensional. I order to complete the information about flow characteristics, measurements were performed in several parallel vertical and horizontal planes along the cylinder.PIV proved to be a good method for the investigation of flow features in the wake of step cylinders for the chosen model dimensions and Reynolds numbers.
34
Sutton, Travis L. « Investigation of IPPD a case study of the Marine Corps AAAV / ». Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1998. http://handle.dtic.mil/100.2/ADA345758.
Texte intégralRésumé :
Thesis (M.S. in Management) Naval Postgraduate School, March 1998.Thesis advisor(s): Susan P. Hocevar, Michael W. Boudreau. "March 1998." Includes bibliographical references (p. 89-92). Also available online.
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Jeong, Gill-Ran. « Investigation of Mineral Dust Aerosols - Chemistry Intractions in the Marine Environments ». Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19805.
Texte intégralRésumé :
Mineral dust aerosols play an important role in atmospheric chemistry through photolysis and heterogeneous uptake. Both mechanisms strongly depend on the size and composition of mineral dust. Because of the complex nature of dust, chemistry modeling commonly relies on simplified assumptions about the properties of dust particles relevant to physiochemical processes. The goal of this thesis is to investigate the impact of size-resolved composition of dust aerosols on atmospheric photochemistry. The relative importance of dust characteristics in photolysis and heterogeneous loss and the relative roles of the two mechanisms on atmospheric photochemistry are investigated.
A new block of spectral aerosol optical properties was developed and incorporated into the tropospheric ultraviolet and visible radiation transfer code in order to calculate spectral actinic fluxes and photolysis rates, J-values. The Fuchs-Sutugin approximation was employed to compute mass transfer from gas to dust mineral species and heterogeneous loss rate, kloss,j. The J-values and kloss,j were incorporated into a one-dimensional photochemistry model to simulate the diurnal cycle of a vertical profile of photochemical species. Several cases of dust loading were considered in the clean and polluted marine environments. A size-resolved mineralogical composition was constructed by selecting a range of the mass fraction of the three main mineral species such as iron oxide-containing clay minerals, carbonate-containing species, and quartz.
This work demonstrates that differences in microphysical and chemical properties of mineral dust lead to the important changes in spectral optical properties, J-values, and kloss,j. It also shows that non-linear relationships of photochemical species with two mechanisms result in various changes in the photochemical oxidant fields and that the most important factor controlling the photochemistry field is the dust size distribution, followed by the amount of mineral species with high uptake coefficients and the amount of iron oxide-clay aggregates.
This work demonstrates that accounting for regional differences in microphysical and chemical properties of mineral dust will improve the assessment of the impact of mineral dust on tropospheric photochemistry. In addition, it suggests that the size and composition of mineral dust will lead to a deeper understanding of the impact of mineral dust on the global climate system.
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Fung, Tak Ching. « Sustainable fisheries and the diversity of marine communities : a theoretical investigation ». Thesis, Queen's University Belfast, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.602508.
Texte intégralRésumé :
Effective implementation of an Ecosystem Approach to Fisheries Management (EA FM) is predicated upon scientific knowledge of how fishing affects biodiversity in large marine communities with > 1 ,000 species, and how changes in biodiversity translate into changes in marine ecosystem functioning. However, existing theoretical and experimental studies have both used systems with orders of magnitude fewer species. Thus, there is a critical need for research using larger, more species-rich systems. The presented thesis addresses this key knowledge gap by developing a unique model capable of producing large model temperate shelf communities each with > 1 ,000 dynamically interacting species. Shelf communities produced from this model are used in a diverse array of in silica experiments to quantify relationships between fishing, biodiversity and marine ecosystem functioning, hitherto unattempted. Firstly, a model community is subjected to 20 fishing scenarios to examine sensitivity of size diversity indicators to fishing and their recovery. Two central results are high sensitivity of size diversity to fishing intensity but not size-selectivity or duration, and slow decadal recovery times. Secondly, 12 different fishing scenarios corresponding to the Celtic and North Seas are applied to two model communities, to predict future recovery of size diversity in these two locations. Results show that for recovery to proposed target levels, fishing intensity must be maintained below mean historical values. Thirdly, a statistical population of 10 communities is used in experiments involving random or ordered deletion of fish species, to quantify relationships between fi sh species richness, two indicators of ecosystem functioning and three indicators of stability of functioning. With decreasing richness, functioning decreased according to a Michaelis-Menten or power-law function. On the other hand, stability increased or exhibited weak trends. Important mechanisms underlying outcomes from all simulations are elucidated. Results from this thesis have important practical implications for current and future implementations of an EAFM.
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Griesel, Jakobus Daniel. « An investigation of tracking of marine mammals / Jakobus Daniel (Kobus) Griesel ». Thesis, North-West University, 2006. http://hdl.handle.net/10394/1352.
Texte intégralRésumé :
Animal tracking devices are frequently used for wildlife studies. Yrless International (PTY) Ltd
specialises in the development of such tracking systems. In an effort to expand their service
related to market needs, a marine mammal tracking system must be developed. This dissertation
forms part of an initial investigation into such a system. The three main aspects that are
addressed are acquiring the animal's location, relaying that information to a server for easy
access and interpreting the data. After this a conceptual design of the system is proposed.
GPS is chosen as tracking method, mainly because similar tracking devices are already in use in
current tracking products, has been used in previous studies and they delivered promising results
during the preliminary study. Tests are done to optimise the GPS receiver in a marine mammal
environment and to keep the GPS in a "warm start" mode to decrease location acquisition time.
Geolocation calculations, which use sunrise and sunset times for estimating location, are
considered as an alternative or complementary method to assist GPS.
For relaying information GSM and RF protocols are investigated. An implementation of RF
protocol is developed with consideration of practical implementation on marine mammals and
optimising power consumption.
A conceptual design is developed from requirements of the final product. The operation of the
marine mammal tracking system is similar to current tracking units.
The knowledge gained from this study and system development serves as important steppingstones
towards providing researchers with a small, efficient and low cost tracking device for
marine mammals.Thesis (M.Ing. (Computer and Electronical Engineering))--North-West University, Potchefstroom Campus, 2007.
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Prescott, Clifford Neill. « Marine geophysical investigation of the Hatton Bank volcanic passive continental margin ». Thesis, Durham University, 1988. http://etheses.dur.ac.uk/6660/.
Texte intégralRésumé :
The Durham/Cambridge/Birmingham Universities two-ship marine geophysical cruise to the Hatton Bank continental margin took place in May/June 1985, during which single- and two-ship seismic reflection/refraction data, together with under way gravity and magnetic anomaly, and bathymetric data were collected within a 200 km by 150 km area straddling the continent-ocean transition. The processing, modelling and interpretation of four two-ship synthetic aperture profiles (SAP) and the gravity and magnetic anomaly data is presented. Gravity models show that a density model based on the crustal velocity structure defined by synthetic seismogram modelling of the two-ship expanding spread profiles is insufficient to reproduce the observed gravity profile across the margin. This requires additional contributions in the form of density gradients in the underlying sub-crustal part of the lithosphere and asthenosphere, and this is investigated by thermal modelling. Analysis of the magnetic anomaly data shows that oceanic magnetic anomalies 21 and 22 are developed in the north-west of the 1985 survey area. Anomalies 23 and 24 cannot be recognised due to post-rift igneous activity and/or subaerial seafloor spreading. The positions of anomalies 23 and 24B are reconstructed within the survey area, and the theoretical anomaly 24B position is used to determine the position of the continent-ocean boundary. Analysis of the anomalies recorded on the upper continental slope shows that the acoustic basement in this area is volcanic. Interpretation of the SAP profiles shows that the margin can be described in terms of three distinct volcanic sequences. The continental sequence is composed of lavas extruded onto continental crust during a period of continental volcanism which occurred before the onset of seafloor spreading just prior to anomaly 24B.The sequence thickens to the north-west, to form a set of seaward-dipping reflectors. The oceanic sequence comprises oceanic crust within which structurally different seaward-dipping dipping reflectors are developed. This sequence is associated with the reconstructed positions of anomalies 23 and 24B, and is interpreted as having formed during a period of subaerial seafloor spreading. The late sequence separates, and in part overlies the continental and oceanic sequences. Magnetic anomalies associated with the late sequence are arcuate, and have high amplitudes, implying an origin other than simple seafloor spreading. The late sequence is interpreted as originating from post-rift igneous activity in the Eocene.
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Ferrier, Graham. « The investigation of coastal and marine processes using remotely sensed data ». Thesis, University of Dundee, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260323.
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Wren, Dominic Kevin. « Surficial marine sediment properties : a geophysical investigation of variability and controls ». Thesis, Bangor University, 1996. https://research.bangor.ac.uk/portal/en/theses/surficial-marine-sediment-properties--a-geophysical-investigation-of-variability-and-controls(4d361ccf-c285-4dfc-ae2f-9a865d0c9eef).html.
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Price, Heather Leigh. « Investigation of larval sensory systems in the marine bryozoan, Bugula neritina ». DigitalCommons@CalPoly, 2015. https://digitalcommons.calpoly.edu/theses/1410.
Texte intégralRésumé :
Bugula neritina is a sessile marine bryozoan with a pelagic larval stage. Larvae frequently settle on boat hulls, facilitating the introduction of B. neritina to bays and estuaries worldwide. Adrenergic agonists, such as the vertebrate hormone noradrenaline, inhibit larval settlement in a variety of marine invertebrate species, including B. neritina. Light also inhibits B. neritina larval settlement, yet the underlying mechanisms by which light and adrenergic compounds exert their effects on larvae are not well understood. Octopamine is considered the invertebrate analog of noradrenaline, and may be an endogenous hormone involved in larval settlement pathways. I observed the effects of the adrenergic agonist noradrenaline and the adrenergic antagonist phentolamine on larval settlement, and found that high concentrations of noradrenaline increased larval mortality, inhibited larval attachment, and increased larval swimming behavior. High concentrations of phentolamine also increased larval mortality, but increased larval attachment and decreased larval swimming behavior. I used fluorescent labeling and microscopy to localize sensory system components, and found that larvae possess adrenergic-like receptors, as well as tyrosine hydroxylase-like and octopamine-like immunoreactivity. I also exposed larvae to phentolamine in both dark and light conditions, and found that light significantly inhibited larval attachment, but phentolamine blocked those inhibitory effects. These results suggest that B. neritina larvae possess adrenergic-like receptors, which serve as the binding sites for noradrenaline and phentolamine. These are likely octopamine receptors, and octopamine may be one endogenous compound involved in controlling larval phototaxis and settlement behavior. Light may increase octopamine production, thereby stimulating cilial activity, extending swimming behavior, and preventing larvae from attaching to a substrate. This research sheds light on previously unknown sensory mechanisms in B. neritina larvae, and may aid in the development of new biofouling control strategies.
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Tsei, Senam Kofi. « An investigation into the sampling bias of Argo profiling floats in the Southern Ocean ». Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/20017.
Texte intégralRésumé :
Numerous Argo floats (approximately 3800 floats) have been deployed in the world's oceans to gather hydrographic and biogeochemical data from the upper 2000 m. However, limited research has been done on the spatial and temporal distribution and potential sampling bias of Argo profiling floats brought on by the effects of bathymetric steering of currents, as well as oceanic features, such as meanders and eddies, that affect their distribution over the global ocean. This study investigates the sampling distribution of profiling floats and assesses the mechanisms that impact their trajectories and distribution in the Atlantic sector of the Southern Ocean. The study reveals that Argo floats are influenced and steered towards frontal jets, which in turn are steered by the underlying bathymetry. Argo floats have a 30 % higher probability of sampling regions where depths range from 4000 - 5000 m, rather than shallow regions of the oceans. Using bootstrapping, this result was shown to be statistically significant at the 95 % confidence interval. The sampling bias is associated with floats becoming entrained into deep reaching frontal jets that occur in the Southern Ocean and dominate the deeper waters. This is shown by analyzing the Argo float positions in relation to mean geostrophic currents which shows that there is a 40 % higher probability (statistically significant at the 95 % confidence level) of finding Argo floats in regions where geostrophic currents range from 0.1 - 0.22 m.s-1 even though the majority of surface currents in the Southern Ocean are found below 0.05 m.s-1. This indicates a non-uniform distribution of Argo floats in the Southern Ocean, which leads to a spatial sampling bias in the float data. This has implications for how we characterize the oceanography or understand the distribution and variability of oceanographic processes and its relation to climate.
43
Petters, Jonathan Leonard. « Investigation of Aerosol Single Scattering Albedo in the Ultraviolet Spectrum ». NCSU, 2002. http://www.lib.ncsu.edu/theses/available/etd-05212002-142505/.
Texte intégralRésumé :
Single scattering albedo (omega), the ratio of scattering coefficient to total extinction coefficient, at UV wavelengths is an important aerosol radiative parameter in determining surface UV irradiance. Surface measurements of total and diffuse UV irradiance in the summer and fall of 1999 at the seven narrowband wavelength channels of an UV multifilter rotating shadowband radiometer (UVMFR-SR) at Black Mountain, NC were coupled with a tropospheric ultraviolet radiative transfer model to produce values of omega. Its value ranged from 0.53 ? 0.94 at 300 nm to 0.55 ? 1.00 at 368 nm. Error in this procedure decreases with increasing aerosol optical depth (AOD), from +/-0.19 at AOD = 0.05 to +/-0.02 at AOD=1.0. Values of omega were not found to be correlated with air mass origin. The current values of omega have a wider variation than values reported from a previous study at the same site, possibly attributable to changes in aerosol chemical composition over time. The value of omega was found to be quadratically correlated with wavelength. Little research has been conducted in the scattering and absorption properties of aerosols in the UV wavelengths, but what has been done suggests such a correlation is possible. More values of omega in the UV spectrum will allow for better estimation of this parameter for UV radiative transfer modeling and will lessen error in estimation of surface UV irradiances.
44
Lee, Wai-ming. « Correlation of PCPT and SPT data from a shallow marine site investigation / ». View the Table of Contents & ; Abstract, 2004. http://sunzi.lib.hku.hk/hkuto/record/B30110385.
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Tucker, David John, et n/a. « An Investigation of the Chemical Constituents of Two Species of Marine Sponge ». Griffith University. Division of Science and Technology, 1990. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20050826.155059.
Texte intégralRésumé :
An investigation of the dichioromethane extract of the sponge, Xestospongia testudinaria indicated that the extract was composed of approximately 40% sterols, 30% saturated fatty acids, 10% mono-unsaturated fatty acids and 20% poly-unsaturated acids. The sterol profile was found to vary between two collections of the sponge. In the first collection the major sterol was the C30 compound, xestosterol (4), which had not previously been reported to occur in this species. In the second collection there was a wider distribution of components with cholesterol (2a) being a major constituent and xestosterol being present in a much lower percentage than in the first collection. The poly-unsaturated acid fraction contained an extremely complex mixture. The novel brominated bisacetylenic C18 (47) and brominated C28 (65) acids were found to be the major components. Another six novel brominated acetylenic acids, which were very unstable, were also identified as well as an ester of 4 with 47. The method developed for the separation of the poly-unsaturated acids from the other classes of metabolites and for the isolation of the pure compounds is discussed and their structural elucidation, largely on the basis of NIMR spectroscopy is described. From the hexane extract of Carteriospongia foliascens, two novel bisalkylated norscalarane derivatives (114 and 116) and a bisalkylated scalarane derivative (130) have been isolated. By use of high field NMR and multipulse NMR techniques a complete assignment of the 111 and 13C NMR spectra of 130 has been achieved on 1.5mg of material. This represents the first report of a complete assignment of the 1J4 NMR spectrum of a scalarane derivative. The C-4 stereochemistry of 130 was determined by use of 1H NMR spectroscopic techniques, which gave results in agreement with the previously used 13C NMR method.
46
Stephen, Robert Craig. « A field investigation of marine anemia in farmed salmon in British Columbia ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1995. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq23929.pdf.
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Johnston, M. P. « A molecular investigation of sodium channel blocking toxin production by marine bacteria ». Thesis, University of Aberdeen, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.590949.
Texte intégralRésumé :
The first step of this work was to determine if seven SCB toxin-producing bacteria and five TTX producers bore plasmids that encoded for toxin production. Only one of the twelve strains was found to have a plasmid and curing it was not possible. It was therefore concluded that, in all likelihood, in the majority of strains tested, toxin-producing genes were located on the chromosome. Although several different classes of signal molecules have been identified to date, most research efforts have concentrated on the N-acyl homoserine lactones (AHLs). The twelve SCB toxin- and TTX producers were tested for AHLs using a suite of biosensors. The bioassays indicated that over half of the strains produced signal molecules, but this was not enough to draw a conclusive correlation between AHLs and toxin production. Surprisingly, bacterium 667-2 (Roseobacter clade) was shown to produce up to six different AHLs. Using Electrospray Ionisation Mass Spectrometry (ESI MS/MS), it was revealed that 667-2 constitutively produces N-(3-hydroxydecanoyl)-L-homoserine lactone, an AHL reported only once before, and hexandecanoyl homoserine lactone, a novel AHL. It was not possible to determine what phenotypes these AHLs regulate, but given the growing interest in Roseobacter, work on this strain may continue. Several groups have reported successful mutagenesis of marine bacteria employing mini-Tn5 vectors. Like other researchers, this work found that antibiotic resistance and DNase production by SCB toxin- and TTX producers limited the scope for selection of genuine mutants. However, diparental filter mating using potassium tellurite to select against the donor and chloramphenicol against the marine recipients was confirmed as successful. The next step in this work would have been to identify non-toxic mutants and sequence their genes in order to elucidate the biosynthetic pathway for toxin production.
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Lee, Wai-ming, et 李慧明. « Correlation of PCPT and SPT data from a shallow marine site investigation ». Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B44570077.
Texte intégral
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Sadri, Saeed Seyed. « Investigation of microplastic debris in marine surface waters using different sampling methods ». Thesis, University of Plymouth, 2015. http://hdl.handle.net/10026.1/3363.
Texte intégralRésumé :
‘Microplastics’ are pieces of plastic debris < 5mm in diameter. They are introduced into the marine environment directly for example via release of small pieces of plastics used as abrasives and indirectly through the fragmentation of larger items. The European Marine Strategy Framework Directive 2008/56/EC (MSFD) regards microplastics as an emerging issue of concern and calls for more data on the quantity, distribution and composition of this debris. This thesis examines the amount, composition and distribution of buoyant microplastic debris in marine waters using different sampling devices and methodologies. To investigate the spatial distribution, abundance and composition of microplastic debris between nearshore and offshore marine subsurface waters a subset of samples from the Continuous Plankton Recorder (CPR) survey were examined. Abundance was generally higher in nearshore coastal waters than the offshore oceanic samples, with the highest mean concentrations observed in the UK’s coastal waters of the northeast Atlantic and the southern North Sea. To validate the accuracy of the presence/absence of microplastic debris reported in the Continuous Plankton Recorder (CPR) samples by analysts at the Sir Alister Hardy Foundation for Ocean Science (SAHFOS) a subset of data was formally analysed using Fourier Transform Infrared (FTIR) spectroscopy. This analysis indicated a good level of accuracy (~66%) in the ability of the SAHFOS’ analysts to detect visually microplastic fragments during their normal processing of plankton samples. To compare quantity and composition of buoyant microplastic debris collected by two different approaches (CPR vs. Manta net) samples were collected from a similar body of coastal waters. The results showed significantly higher abundance of microplastic in samples collected by the manta net per unit of distance but no significant difference once the results were standardised per cubic volume of water. To assess the susceptibility of each method to ‘procedural contamination’, repetitive controlled tests were conducted to quantify the amount and composition of contaminants before, during and after the sampling programme. In both methods the highest number of contaminants was found on the net and prior to the deployment to sea. The semi synthetic Rayon fibres were the most abundant type of contaminants in both cases. To compare the abundance and composition of buoyant plastic debris in estuarine waters according to daily and lunar tidal cycles a mensurative experiment was conducted in a macrotidal Estuary. Microplastics comprised 82% of the debris and there was a significant difference in size frequency distribution between the spring and neap tides with more fragments of larger size observed during spring tides. In conclusion, this study shows further evidence of the spatial heterogeneity of microplastic debris distribution in marine waters and therefore also highlights the need for more comparable data from different marine habitats using standardised methodologies.
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Tucker, David John. « An Investigation of the Chemical Constituents of Two Species of Marine Sponge ». Thesis, Griffith University, 1990. http://hdl.handle.net/10072/367459.
Texte intégralRésumé :
An investigation of the dichioromethane extract of the sponge, Xestospongia testudinaria indicated that the extract was composed of approximately 40% sterols, 30% saturated fatty acids, 10% mono-unsaturated fatty acids and 20% poly-unsaturated acids. The sterol profile was found to vary between two collections of the sponge. In the first collection the major sterol was the C30 compound, xestosterol (4), which had not previously been reported to occur in this species. In the second collection there was a wider distribution of components with cholesterol (2a) being a major constituent and xestosterol being present in a much lower percentage than in the first collection. The poly-unsaturated acid fraction contained an extremely complex mixture. The novel brominated bisacetylenic C18 (47) and brominated C28 (65) acids were found to be the major components. Another six novel brominated acetylenic acids, which were very unstable, were also identified as well as an ester of 4 with 47. The method developed for the separation of the poly-unsaturated acids from the other classes of metabolites and for the isolation of the pure compounds is discussed and their structural elucidation, largely on the basis of NIMR spectroscopy is described. From the hexane extract of Carteriospongia foliascens, two novel bisalkylated norscalarane derivatives (114 and 116) and a bisalkylated scalarane derivative (130) have been isolated. By use of high field NMR and multipulse NMR techniques a complete assignment of the 111 and 13C NMR spectra of 130 has been achieved on 1.5mg of material. This represents the first report of a complete assignment of the 1J4 NMR spectrum of a scalarane derivative. The C-4 stereochemistry of 130 was determined by use of 1H NMR spectroscopic techniques, which gave results in agreement with the previously used 13C NMR method.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Division of Science and Technology
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