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Search Results: 1 - 10 of 653557 matches for " J. A. McCordic "
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Utilizing Occupancy Models and Platforms-of-Opportunity to Assess Area Use of Mother-Calf Humpback Whales  [PDF]
J. J. Currie, S. H. Stack, J. A. McCordic, J. Roberts
Open Journal of Marine Science (OJMS) , 2018, DOI: 10.4236/ojms.2018.82014
Abstract:
The Hawaiian Islands, and particularly the Maui 4-island region, are a critical breeding and calving habitat for humpback whales (Megaptera novaeangliae) belonging to the Hawaii distinct population segment. Our aims were to test the use of platforms-of-opportunity to determine trends in mother-calf pod use of the region and to present opportunistic platforms as an alternative method of long-term, cross-seasonal monitoring. Data were collected from whale watching vessels over a 4-year period and analyzed using occupancy models to determine the probability of habitat use of pods with calves and pods without calves within the study area. Detection probability was influenced by survey effort and month for all pod types with detection of adult only pods further influenced by year. Pods with a calf showed a preference for shallow (<100 meters) low latitude waters (<20.7°N), while pods without a calf preferred deeper waters (>75 meters). Results presented here align with previous work, both in Hawaii and in other breeding grounds, which show a distinct segregation of mothers with a calf from other age-classes of humpback whales. The need for long-term continuous monitoring of cetacean populations is crucial to ensure species conservation. Data collected aboard platforms-of-opportunity, as presented here, provide important insight on humpback whale spatial and temporal distribution, which are essential for species protection and management.
Remote Acoustic Monitoring of North Atlantic Right Whales (Eubalaena glacialis) Reveals Seasonal and Diel Variations in Acoustic Behavior
Leanna P. Matthews, Jessica A. McCordic, Susan E. Parks
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0091367
Abstract: Remote acoustic monitoring is a non-invasive tool that can be used to study the distribution, behavior, and habitat use of sound-producing species. The North Atlantic right whale (Eubalaena glacialis) is an endangered baleen whale species that produces a variety of stereotyped acoustic signals. One of these signals, the “gunshot” sound, has only been recorded from adult male North Atlantic right whales and is thought to function for reproduction, either as reproductive advertisement for females or as an agonistic signal toward other males. This study uses remote acoustic monitoring to analyze the presence of gunshots over a two-year period at two sites on the Scotian Shelf to determine if there is evidence that North Atlantic right whales may use these locations for breeding activities. Seasonal analyses at both locations indicate that gunshot sound production is highly seasonal, with an increase in the autumn. One site, Roseway West, had significantly more gunshot sounds overall and exhibited a clear diel trend in production of these signals at night. The other site, Emerald South, also showed a seasonal increase in gunshot production during the autumn, but did not show any significant diel trend. This difference in gunshot signal production at the two sites indicates variation either in the number or the behavior of whales at each location. The timing of the observed seasonal increase in gunshot sound production is consistent with the current understanding of the right whale breeding season, and our results demonstrate that detection of gunshots with remote acoustic monitoring can be a reliable way to track shifts in distribution and changes in acoustic behavior including possible mating activities.
Effect of Annealing Temperature on Structural, Optical and Electrical Properties of Pure CdS Thin Films Deposited by Spray Pyrolysis Technique  [PDF]
A. Hasnat, J. Podder
Advances in Materials Physics and Chemistry (AMPC) , 2012, DOI: 10.4236/ampc.2012.24034
Abstract:

Effect of annealing temperature on the properties of CdS thin films are carried out in this work. Nanocrystalline cadmium sulphide (CdS) thin films were prepared using spray pyrolysis deposition (SPD) technique and the structural, optical and electrical properties were investigated for different annealing temperature (as deposited, 300, 400 & 500 C). The surface morphology and compositional properties studied by SEM and EDX respectively. The crystal structure of CdS thin film was studied by X-ray diffraction. The crystallite size and lattice constant of SPD CdS thin films were investigated. The optical parameters such as transmittance, absorption coefficient and energy band gap of the films with thermal annealing temperature was investigated by UV/VIS spectrophotometer. The variation of band gap values of CdS thin film samples were found to be in the range of 2.51 to 2.8 eV. Electrical resistivity measurements were carried out in fourprobe Vander Pauw method at different temperature. So CdS films may be a good candidate for suitable application in various optoelectronic devices.

The 1964 Wellington Study of Beatlemania Revisited  [PDF]
A. J. W. Taylor
Psychology (PSYCH) , 2014, DOI: 10.4236/psych.2014.515190
Abstract: In June 1964, an Honours class in clinical psychology set out to objectify the major parameters of crowd and audience reaction to the Beatles’ during the group’s three-day visit to Wellington, New Zealand. Advance publicity had warned of the “mass-hysteria” to be expected at the sight, sound and lyrics of the four lads from Liverpool. Adolescents anticipated their arrival eagerly, while the authorities were disparaging and somewhat fearful of the breakdown in law and order that might occur. The findings were published in Britain in 1966, taken a little further in the United States in1968, and the original published once more in Britain in 1992 by special request to encourage more psychologists to undertake research off campus. When writers from those countries mentioned the study recently near the 50th anniversary of the Beatles’ visit, it seemed interesting to review the accretion of similar studies that might have occurred. Sadly, the outcome showed that psychologists had not taken mass-audience research any further. Hence it was thought appropriate to lift the Wellington study from obscurity, in the hope of inspiring the next generation to make amends.
Preparation and Structural Characterization of Vanadium Doped Ni – B Binary Hard Alloys  [PDF]
J. A. Ajao
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2010, DOI: 10.4236/jmmce.2010.96040
Abstract: The microstructure of a series of binary Ni-B alloys containing various amounts of vanadium additions were investigated by Differential Thermal Analysis (DTA), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Energy Dispersive X-ray Analysis (EDXA). Due to the vanadium addition in the alloys quenched from the liquidus, the formation of the Ni3B phase was enhanced even when the nominal composition was hypoeutectic. The addition of vanadium led to the formation of t (Ni20.4V2.6B6) phase during the present investigation. In addition, the crystallographic orientation relationship of this ternary phase with the nickel matrix was reported. The solid-state eutectoid transformation of the Ni3B phase during cooling was also reported and discussed.
Effect of Solidification Process Parameters on the Microstructure of Some Meltspun Nickel-Based Hardfacing Alloys  [PDF]
J. A. Ajao
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2009, DOI: 10.4236/jmmce.2009.810067
Abstract: The influence of solidification parameters on the morphology of a number of meltspun Nickelbased hard alloys has been investigated by means of scanning electron microscopy (SEM), conventional transmission electron microscopy and energy dispersive X-ray analysis (EDXA). It was established that the wheel velocity played a prominent role in the types of microstructure observed. Very high wheel velocity could lead to the formation of amorphous structure as observed in some of the alloys investigated. No appreciable effect of the ribbon thickness was observed on the microhardness of the alloys. It was also reported that the thermal transfer mode between the ideal and newtonian coolings was observed in all the alloys investigated.
Scanning Electron Microscopy of Some Slowly Cooled Nickel-Based Hardfacing Alloys Containing Iron Additions  [PDF]
J. A. Ajao
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2010, DOI: 10.4236/jmmce.2010.92012
Abstract: The service lifespan of components used at higher temperatures in corrosive and abrasive environments can be prolonged by high-temperature corrosion-resistant coatings. This study is concerned with the microstructural characterization of some slowly cooled Nickel–based hardfacing alloys investigated by differential thermal analysis (DTA), energy dispersive X – ray analysis (EDXA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The alloys were prepared in high frequency induction furnace under controlled atmosphere. Three major primary hard phases (Ni (α), M7C3, and the π phase) were identified during slow cooling in DTA depending on the nominal compositions of the alloys. Large undercoolings as well as intense solid state precipitations were observed in alloys with iron additions. The precipitations formed the basis of the high hardness values and strength of the alloys. It was also reported that the hardness values of the alloys increased as the iron contents increased.
Electrochemical Separation of Metal Silver from Industrial Wastewater  [PDF]
M. A. Olutoye, J. A. Alhamdu
Advances in Chemical Engineering and Science (ACES) , 2014, DOI: 10.4236/aces.2014.44043
Abstract: Investigation into the separation of metal silver from industrial wastewater using electrochemical cell was carried out. Wastewater from photo laboratories was collected and treated batch wise using electrolytic equipment. A constant voltage of 2.0 V and variable current in the range of 0.3 - 0.6 A at normal temperature were passed through the electrolyte for a period from 0.25 - 1.0 h. The results showed that increase in current yield an increase in the amount of metallic silver recovered with highest values of 2.3 g and 2.8 g at 0.6 A for the tested samples 1 and 2, respectively. The electrochemical separation method proved to be more reliable and economical when compared to other methods and also, reduction in environmental pollution of industrial wastewater containing high concentration of silver metal is achieved.
Study of the Effect of Cu2+ in the Lattice Dynamics of Doped Magnetites Obtained by the Hydrothermal Synthesis Method  [PDF]
A. A. Velásquez, J. P. Urquijo
Spectral Analysis Review (SAR) , 2013, DOI: 10.4236/sar.2013.12002
Abstract: In this work, the effect of Cu2+ on the structural and magnetic properties of samples of magnetite is addressed. Samples
of magnetite, both pure and Cu2+ doped, Fe3-xCuxO4, with x = 0, 5, 10 and 20 atm.% were synthesized hydrothermally. The two-lattice method was employed to measure the Mossbauer recoilless fraction of magnetite relative to hematite (fmag/fhem)
of the samples, looking for evidence of substitution of Fe2+ by Cu2+. The relative recoilless fraction measurements were performed by taking room temperature Mossbauer spectra of mixtures of each sample with analytical grade hematite. The Mossbauer measurements were complemented with Atomic Absorption Spectroscopy (AAS) and Energy Dispersive X-ray Spectroscopy (EDS). The analyses by AAS and EDS showed that the copper concentration in the final products
increases with increasing the content of Cu2+ in the starting solutions. The Mossbauer analyses showed a linear decrease trend of the relative Mossbauer recoilless fraction with increasing concentration of Cu2+in the samples, as well as a reduction in the hyperfine magnetic field, which was more significant in the octahedral sites than tetrahedral sites. The broadening of the Mossbauer spectral lines was more significant for the octahedral sub spectrum than for the tetrahedral sub spectrum. Our study points that Cu2+ occupies preferentially the octahedral sites, where it substitutes Fe2+ species, generating broadening in the lines of the octahedral sub spectrum and a reduction in the probability of having nuclear resonant absorption of Mossbauer gamma rays in the samples.

Exactly Solvable Schr?dinger Equation with Hypergeometric Wavefunctions  [PDF]
J. Morales, J. García-Martínez, J. García-Ravelo, J. J. Pe?a
Journal of Applied Mathematics and Physics (JAMP) , 2015, DOI: 10.4236/jamp.2015.311173
Abstract: In this work, the canonical transformation method is applied to a general second order differential equation (DE) in order to trasform it into a Schr?dinger-like DE. Our proposal is based on an auxiliary function g(x) which determines the transformation needed to find exactly-solvable potentials associated to a known DE. To show the usefulness of the proposed approach, we consider explicitly their application to the hypergeometric DE with the aim to find quantum potentials with hypergeometric wavefunctions. As a result, different potentials are obtained depending on the choice of the auxiliary function; the generalized Scarf, Posh-Teller, Eckart and Rosen-Morse trigonometric and hyperbolic potentials, are derived by selecting g(x) as constant and proportional to the P(x) hypergeometric coefficient. Similarly, the choices g(x)~P(x)/x2 and g(x)~x2/P(x) give rise to a class of exactly-solvable generalized multiparameter exponential-type potentials, which contain as particular cases the Hulthén, Manning-Rosen and Woods-Saxon models, among others. Our proposition is general and can be used with other important DE within the frame of applied matematics and physics.
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