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2004

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Articles 3751 - 3780 of 3873

Full-Text Articles in Physical Sciences and Mathematics

Interactive Regulation Of Dissolved Copper Toxicity By An Estuarine Microbial Community, Christina L. Dryden, Andrew S. Gordon, John R. Donat Jan 2004

Interactive Regulation Of Dissolved Copper Toxicity By An Estuarine Microbial Community, Christina L. Dryden, Andrew S. Gordon, John R. Donat

OES Faculty Publications

Cultured marine microorganisms under copper stress produce extracellular compounds having a high affinity for copper (copper-complexing ligands). These ligands are similar in binding strength to those found in natural waters, but few studies have examined the relationship between copper, copper-complexing ligand concentrations, and natural microbial populations. A series of in situ experiments in the Elizabeth River, Virginia, revealed that an intact estuarine microbial community responded to copper stress by production of extracellular, high-affinity copper-complexing ligands. The rate of ligand production was dependent on copper concentration and resulted in a reduction of the concentration of free cupric ions, Cu2+, …

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Light Dependence Of Selenium Uptake By Phytoplankton And Implications For Predicting Selenium Incorporation Into Food Webs, Stephen B. Baines, Nicholas S. Fisher, Martina A. Doblin, Gregory A. Cutter, Lynda S. Cutter, Brian Cole Jan 2004

Light Dependence Of Selenium Uptake By Phytoplankton And Implications For Predicting Selenium Incorporation Into Food Webs, Stephen B. Baines, Nicholas S. Fisher, Martina A. Doblin, Gregory A. Cutter, Lynda S. Cutter, Brian Cole

OES Faculty Publications

The potentially toxic element selenium is first concentrated from solution to a large but highly variable degree by algae and bacteria before being passed on to consumers. The large loads of abiotic and detrital suspended particles often present in rivers and estuaries may obscure spatial and temporal patterns in Se concentrations at the base of the food web. We used radiotracers to estimate uptake of both selenite (Se(IV)) and C by intact plankton communities at two sites in the Sacramento/San Joaquin River Delta. Our goals were to determine (1) whether C and Se(IV) uptake were coupled, (2) the role of …

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Physical Forcing Of Phytoplankton Community Structure And Primary Production In Continental Shelf Waters Of The Western Antarctic Peninsula, Barbara B. Prézelin, Eileen E. Hofmann, Mark Moline, John M. Klinck Jan 2004

Physical Forcing Of Phytoplankton Community Structure And Primary Production In Continental Shelf Waters Of The Western Antarctic Peninsula, Barbara B. Prézelin, Eileen E. Hofmann, Mark Moline, John M. Klinck

OES Faculty Publications

Analyses of a multidisciplinary data set, collected in continental shelf waters of the Western Antarctic Peninsula (WAP) during austral summer of January 1993, identified a previously unrecognized forcing mechanism that sets up a physical and chemical structure that supports and assures site-specific diatom-dominated communities and enhanced biological production (Prézelin et al., 2000). This forcing is active when the southern boundary of the Antarctic Circumpolar Current (ACC) flows along the shelf edge, thereby facilitating onshelf bottom intrusions of nutrient-rich Upper Circumpolar Deep Water (UCDW), which then is upwelled or mixed into the upper water column. At times or locations where UCDW …

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Lipid-Lowering Effects Of Ethyl 2-Phenacyl-3-Aryl-1h-Pyrrole- 4-Carboxylates In Rodents, Justin M. Holub, Kathy O'Toole-Colin, Adam Getzel, Anthony Argenti, Michael A. Evans, Daniel C. Smith, Gerard A. Dalglish, Shahzad Rifat, Donna L. Wilson, Brett M, Taylor, Ulander Miott, Josephine Glersaye, Kam Suet Lam, Bryan J. Mccranor, Joshua D. Berkowitz, Robert B. Miller, John R. Lukens, Keith Krumpe, John T. Gupton, Bruce S. Burnham Jan 2004

Lipid-Lowering Effects Of Ethyl 2-Phenacyl-3-Aryl-1h-Pyrrole- 4-Carboxylates In Rodents, Justin M. Holub, Kathy O'Toole-Colin, Adam Getzel, Anthony Argenti, Michael A. Evans, Daniel C. Smith, Gerard A. Dalglish, Shahzad Rifat, Donna L. Wilson, Brett M, Taylor, Ulander Miott, Josephine Glersaye, Kam Suet Lam, Bryan J. Mccranor, Joshua D. Berkowitz, Robert B. Miller, John R. Lukens, Keith Krumpe, John T. Gupton, Bruce S. Burnham

Chemistry Faculty Publications

A series of substituted 2-phenacyl-3-phenyl-1H-pyrrole-4-carboxylates were prepared from substituted acetophenones in 6 steps. The final condensations between a chloroenal and an aminoketone were carried out under neutral conditions in parallel to yield the series listed below. Selected pyrrole derivatives proved to be potent hypolipidemic agents lowering serum triglyceride concentrations in CF-1 male mice after 14 days of I.P. administration. One agent orally lowered serum cholesterol in Sprague-Dawley male rats at 2mg/kg/day after 14 days. The agents demonstrated a lowering of mouse serum LDL- cholesterol levels and selected compounds showed an elevation of serum HDL-cholesterol levels. The cholesterol concentrations in the …

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Methyl Bromide In Preindustrial Air: Measurements From An Antarctic Ice Core, Eric S. Saltzman, Murat Aydin, Warren J. De Bruyn, Daniel B. King, Shari A. Yvon-Lewis Jan 2004

Methyl Bromide In Preindustrial Air: Measurements From An Antarctic Ice Core, Eric S. Saltzman, Murat Aydin, Warren J. De Bruyn, Daniel B. King, Shari A. Yvon-Lewis

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

This paper presents the first ice core measurements of methyl bromide (CH3Br). Samples from a shallow Antarctic ice core (Siple Dome, West Antarctica), ranging in mean gas dates from 1671 to 1942, had a mean CH3Br mixing ratio of 5.8 ppt. These results extend the existing historical record derived from air and Antarctic firn air to about 350 years before present. Model simulations illustrate that the ice core results are consistent with estimates of the impact of anthropogenic activity ( fumigation, combustion, and biomass burning) on the atmospheric CH3Br burden, given the large current uncertainties in the modern atmospheric CH3Br …

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The Born Scattering Amplitude Of A Non-Relativistic Spin One-Half Particle In An Aharonov-Bohm Potentia, Yousef Romia, Mohammad Shikakhwa Jan 2004

The Born Scattering Amplitude Of A Non-Relativistic Spin One-Half Particle In An Aharonov-Bohm Potentia, Yousef Romia, Mohammad Shikakhwa

Turkish Journal of Physics

The Born scattering amplitude of a non-relativistic spin one-half particle in an Aharonov-Bohm potential is calculated up to second order. It is demonstrated that perturbation theory works well for this model, in contrast with the case of scalar particles, thanks to the spin-magnetic moment interaction term. The first order amplitude is shown to coincide with the exact amplitude when expanded to the same order; the second order amplitude is finite and null. The polarized scattering cross section is found to be different from the unpolarized one only if the incident particle has a spin component perpendicular to the flux tube.

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Quantum Statistical Entropy Of Sen Black Hole, Zhao Ren, Wu Yueqin, Zhang Lichun Jan 2004

Quantum Statistical Entropy Of Sen Black Hole, Zhao Ren, Wu Yueqin, Zhang Lichun

Turkish Journal of Physics

In this paper, by using quantum statistical methods, we directly obtain the partition function of Bose field and Fermi field on the background of the axisymmetrical Sen black hole. The difficult-to-solve wave equation is avoided. Then via the improved brick-wall method and membrane model, we calculate the entropy of Bose field and Fermi field of the black hole. We find that the entropy of the black hole is proportional to the area of the horizon. In our results, we do not encounter the left out term nor the divergent logarithmic term that appears in the original brick-wall method. The question …

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E2/M1 Multipole Mixing Ratios Of Transitions In Erbium Isotopes, Harun Reşi̇t Yazar, İhsan Uluer Jan 2004

E2/M1 Multipole Mixing Ratios Of Transitions In Erbium Isotopes, Harun Reşi̇t Yazar, İhsan Uluer

Turkish Journal of Physics

Erbium isotopes (Z = 64) lie in the transitional region that occurs at the middle of the range of deformed nuclei. \gamma -ray E2/M1 mixing ratios for selected transitions in ^{166-168}Er are calculated in the proton-neutron interacting boson approximation(IBA-2). The results obtained for ^{166 -168}Er are reasonably in good agreement with the previous experimental and teoretical values.

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Large Amplitude Wave Trains In Cosmic Ray Intensity, Rajesh K. Mishra, Rekha Agarwal Mishra Jan 2004

Large Amplitude Wave Trains In Cosmic Ray Intensity, Rajesh K. Mishra, Rekha Agarwal Mishra

Turkish Journal of Physics

Using ground-based neutron monitor data of Deep River, the high amplitude anisotropic wave train events (HAE) in cosmic ray intensity have been investigated during the period 1991--1994. It has been observed that the phase of diurnal anisotropy for majority of HAE cases remains in the same co-rotational direction, whereas for some HAE cases the phase of diurnal anisotropy has shifted to later hours. For the majority of HAE cases the amplitude of semi-diurnal anisotropy remains statistically the same, whereas the phase of semi-diurnal anisotropy for all HAE cases has shifted to later hours. Furthermore, for tri-diurnal anisotropy the phase shifts …

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Structural And Magnetic Properties Of Co_{0.6}Znn_{0.4}Mn_{X}Fe_{2 - X}O_{4}, O.M. Hemeda Jan 2004

Structural And Magnetic Properties Of Co_{0.6}Znn_{0.4}Mn_{X}Fe_{2 - X}O_{4}, O.M. Hemeda

Turkish Journal of Physics

A series of Co-Zn ferrite samples substituted by Mn were prepared by the usual double sintering ceramic technique. The x-ray diffraction patterns of the samples confirmed the formation of single-phase spinel structure, and x-ray analysis supply data that suggests the cation distribution of the material. The tetrahedral and octahedral radius permits one to calculate the theoretical lattice parameter and the bond lengths Fe-O at A and B sites. The particle size of the given samples was measured from the Scherer equation and a correlation was found between particle size, and structural and magnetic properties. The XRF confirmed the presence of …

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The Normal And Inverted Meyer-Neldel Rule In The Ac Conductivity, Fouad Abdel-Wahab Jan 2004

The Normal And Inverted Meyer-Neldel Rule In The Ac Conductivity, Fouad Abdel-Wahab

Turkish Journal of Physics

Recently, a new approach has been proposed for the correlated barrier hopping (CBH) model where the ac relaxation time is thought to obey the Meyer-Neldel (MN) rule. This approach gives quantitative agreement with some reliable published experimental data. We report on an experiment involving the characterization of the ac conductivity of Se-Te thin films over a wide range of frequencies and temperatures, carried out in order to confirm applicability of the MN rule to the ac conductivity. In addition to the normal MN rule, the inverted MN rule was observed.

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Realizations Of The Osp(2,1) Superalgebra And Related Physical Systems, Hayri̇ye Tütüncüler, Ramazan Koç Jan 2004

Realizations Of The Osp(2,1) Superalgebra And Related Physical Systems, Hayri̇ye Tütüncüler, Ramazan Koç

Turkish Journal of Physics

Eigenvalues and eigenfunction of two-boson 2 \times 2 Hamiltonians in the framework of the superalgebra osp(2,1) are determined by presenting a similarity transformation. The Hamiltonians include two bosons and one fermion have been transformed in the form of the one variable differential equations and the conditions for its solvability have been discussed. It is observed that the Hamiltonians of the various physical systems can be written in terms of the generators of the osp(2,1) superalgebra and under some certain conditions their eigenstates can exactly be obtained. In particular, the procedure given here is useful in determining eigenstates of the Jaynes-Cummings …

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The Riemann Zeta Function Applied On Glassy Systems And Neural Networks, Viorel L. Cartas Jan 2004

The Riemann Zeta Function Applied On Glassy Systems And Neural Networks, Viorel L. Cartas

Turkish Journal of Physics

Glassy systems and Neural networks share a simple model of study: the model of a set of N non interacting harmonic oscillators with energy. In this paper the author tries to describe these complex systems in order to find the energy involved. The mathematical method used is described in detail.

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Analysis Of One-Nucleon Transfer Cross-Sections, A. K. A. R. Al-Farra Jan 2004

Analysis Of One-Nucleon Transfer Cross-Sections, A. K. A. R. Al-Farra

Turkish Journal of Physics

The angular distributions of ^{26}Mg(^3H,^2H)^{27}Mg and ^{30}Si(^3H,^2H)^{31}Si reactions have been successfully studied using distorted wave Born approximation (DWBA) calculations. The optical model potentials are taken to have Woods-Saxon, parity and spin-orbit interactions. The present analysis gives a satisfactory fit to the forward angle data but grossly over estimates the cross-sections in the backward regions. The spin-orbit potential provides the best description of the experimental data and is found to be necessary to account for the large-angle cross sections. The obtained values of the extracted spectroscopic factors are reasonable.

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Exceptionaly Low Amplitude Anisotropic Wave Train Events In Cosmic Ray Intensity, Rajesh K. Mishra, Rekha Agarwal Mishra Jan 2004

Exceptionaly Low Amplitude Anisotropic Wave Train Events In Cosmic Ray Intensity, Rajesh K. Mishra, Rekha Agarwal Mishra

Turkish Journal of Physics

The unusually low amplitude anisotropic wave train events (LAEs) in cosmic ray intensity using the ground-based Deep River neutron monitor data has been studied during the period 1991--94. It has been observed that the phase of the diurnal anisotropy for majority of the LAE events remains in the corotational direction. However, for some of the LAE events the phase of the diurnal anisotropy shifts towards earlier hours. On the other hand, the amplitude of the semi-diurnal anisotropy remains statistically the same whereas, phase shift towards later hours; similar trend has also been found in case of tri-diurnal anisotropy. The interplanetary …

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On Electron Mobility In A Rectangular Quantum Wire Due To Alloy Disorder, Guseyn Behbudoglu Ibragimov Jan 2004

On Electron Mobility In A Rectangular Quantum Wire Due To Alloy Disorder, Guseyn Behbudoglu Ibragimov

Turkish Journal of Physics

Analytic expressions are derived to describe the electron mobility and relaxation rate in the rectangular quantum wire experiencing scattering due to alloy disorder. The dependence of electron mobility on the temperature and transverse dimension is numerically evaluated and it is found that the mobility increases continuously with temperature, because there is no new intersubband scattering with increase in temperature. It is shown that the alternating increase/decrease in the mobility---depending on the transverse dimension of the quantum wire---occurs due to intersubband scattering. It is found that the mobility in a quantum wire is significantly greater than mobility in a quantum well.

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Raman Scattering In Layered Cdingas_4, Aydin Kulibekov Jan 2004

Raman Scattering In Layered Cdingas_4, Aydin Kulibekov

Turkish Journal of Physics

Raman scattering spectra of CdInGaS_4 crystals grown by the chemical transport method were measured at room and liquid-nitrogen temperatures. Band pairs at 29-38, 43-48 and 60-65 cm^{-1} are reported for the first time. The origin of these bands is attributed to the Davydov doublets, arising due to a small interlayer interaction. Seventeen bands observed in the Raman spectra are assigned to normal modes on the basis of the C_{3v}^1 space group. This modification contains two layers per unit cell and do not have inversion symmetry. It is shown that the crystals grown from the vapor phase and by the Bridgman …

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Empirical Correlations Of Global Solar Radiation With Meteorological Data For Onne, Nigeria, Louis E. Akpabio, Sunday O. Udo, Sunday E. Etuk Jan 2004

Empirical Correlations Of Global Solar Radiation With Meteorological Data For Onne, Nigeria, Louis E. Akpabio, Sunday O. Udo, Sunday E. Etuk

Turkish Journal of Physics

Multiple linear regression models were developed to estimate the monthly average daily global solar radiation using ten parameters during a period of sixteen years (1984 to 1999) for Onne, Nigeria; the extraterrestrial radiation, average daily temperature, ratio of minimum and maximum daily temperature, relative humidity, ratio of sunshine duration, solar declination, average soil temperature, average pan evaporimeter, average rain fall and average daily dew. Even though up to ten variable correlations has been developed; the results showed that eight variable correlations with the highest value of correlation coefficient R gives the best result when considering the error terms (mean percentage …

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Comparative Study Of First Two Harmonics In Cosmic Ray Intensity For The Period 1964-95, Rekha Agarwal Mishra, Rajesh K. Mishra Jan 2004

Comparative Study Of First Two Harmonics In Cosmic Ray Intensity For The Period 1964-95, Rekha Agarwal Mishra, Rajesh K. Mishra

Turkish Journal of Physics

The Deep River neutron monitor data has been harmonically analyzed for the period 1964--95 covering three solar cycles 20, 21 and 22, looking for a long term trend of the diurnal and semi-diurnal anisotropies of cosmic ray intensity on geomagnetically 60 quiet days. The amplitude of both the harmonics remains statistically constant during 1964-70. The amplitudes of the first harmonic is found to be low during 1965, 1967, 1976-77, 1986-87, 1991, 1993 and 1995. The amplitude of diurnal anisotropy acquired exceptionally large values in 1985, whereas semi-diurnal anisotropy acquired large values in 1974-75 and in 1984, which coincided with epochs …

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Determination Of The Rotational Constant A_0 And The Bending Angle Cnc For Ch_3 Nc And Ch_3 ^{15}Nc Molecules, Mohammad Al-Share Jan 2004

Determination Of The Rotational Constant A_0 And The Bending Angle Cnc For Ch_3 Nc And Ch_3 ^{15}Nc Molecules, Mohammad Al-Share

Turkish Journal of Physics

The rotational constant A_0 for the ground state of CH_3 NC and CH_3 ^{15}NC isotopomers is calculated using a technique which was used earlier for CH_3CCH [9], CH_3CN [10] and SiH_3CCH [11]. This technique is based on calculating the moment of inertia tensors in the bent configuration due to the \nu_8 vibrational state, which is associated with the CNC bending vibration. These values of the moments of inertia are fitted with the values calculated from the rotational constant B_V, found experimentally by measuring the rotational frequencies in the microwave and infrared regions. From the fitting, the rotational constant A_0, the …

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Structure And Dielectric Behaviour Of Barium Cupro Molybdate Ceramic, N. G. Durge, M. S. Nadkarni, S. V. Salvi Jan 2004

Structure And Dielectric Behaviour Of Barium Cupro Molybdate Ceramic, N. G. Durge, M. S. Nadkarni, S. V. Salvi

Turkish Journal of Physics

The ceramic of new perovskite Ba (Cu_{1/2} Mo_{1/2}) O_3 has been synthesized at 1200 °C for 24 hours. The XRD analysis indicates an ordered hexagonal structure, which is attributed to large valency difference between octahedral cations. The IR spectrum reveals the presence of Cu-O-Mo ordered bond. The room temperature relaxation spectra imply a large conductivity term and multiple `Debye terms' at low frequencies. This is attributed to presence of the space charge. The variation of dielectric constant with temperature has been investigated from room temperature to 800 K. The diffusivity constant equal to 1 implies normal ferroelectric behaviour near room …

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A Novel Radiative Substrate Heater, Abdullah Ceylan, Erdal Kaynak, Şadan Özcan, Tezer Firat Jan 2004

A Novel Radiative Substrate Heater, Abdullah Ceylan, Erdal Kaynak, Şadan Özcan, Tezer Firat

Turkish Journal of Physics

In this work, we have developed a new low cost radiative substrate heater for deposition of high-T_c superconducting thin films. It has all the features required for the preparation of high quality superconducting thin films. It is possible to reach ~ 800 °C substrate temperature with it by using only one 250 W halogen projector bulb.

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Effect Of Development Time On Polymer Phase Separation In A Pmma Resist, Mohammad Naeem Khalid, Shazia Yasin, Mohammad Riaz Khan Jan 2004

Effect Of Development Time On Polymer Phase Separation In A Pmma Resist, Mohammad Naeem Khalid, Shazia Yasin, Mohammad Riaz Khan

Turkish Journal of Physics

Developer composition type and development technique are known to influence surface and edge roughness in polymethylemethacrylate (PMMA); and it is during development, we believe, that the result is most influenced by the phase separation into polymer-rich and polymer-poor regions. This polymer phase separation is more prominent in a weaker developer and low temperature. In this paper, we investigate the effect of development time on the extent of polymer phase separation in an exposed PMMA developed in a standard developer i.e. 1:3 MIBK:IPA at 20 °C and rinsed in pure IPA for 30 sec. The polymer phase separation is found to …

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Thermochemical And Green Luminescence Analysis Of Zinc Oxide Thin Films Grown On Sapphire By Chemical Vapor Deposition, Abdelkader Djelloul, R. A. Rabadanov Jan 2004

Thermochemical And Green Luminescence Analysis Of Zinc Oxide Thin Films Grown On Sapphire By Chemical Vapor Deposition, Abdelkader Djelloul, R. A. Rabadanov

Turkish Journal of Physics

This study has been carried out to detail an integral thermochemical analysis of the principal reaction in the production of zinc oxide (ZnO) thin films, including developing an analytical form of the equilibrium constant. Zinc oxide thin films prepared by chemical vapor deposition have been studied in terms of deposition time and substrate temperature. The growth of the single-crystal films present two regimes depending on the substrate temperature, with increasing constant growth rates at lower, and higher, temperature ranges, respectively. Growth rates above 6 \mu m \cdot min^{-1} can be achieved at T_s = 880 K. The variation of the …

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Polar Optical Phonon Modes And Fröhlich Electron-Phonon Interaction Hamiltonians In Coaxial Cylindrical Quantum Cables, Li Zhang, Hong-Jing Xie Jan 2004

Polar Optical Phonon Modes And Fröhlich Electron-Phonon Interaction Hamiltonians In Coaxial Cylindrical Quantum Cables, Li Zhang, Hong-Jing Xie

Turkish Journal of Physics

By using the dielectric continuum approximation, the polar optical phonon modes of coaxial cylindrical quantum cables with arbitrary layer-number were studied. In order to describe the vibrating of the longitudinal-optical (LO) phonons, a set of legitimate eigenfunctions for LO phonon modes are constructed and adopted. In order to deal with the interface optical (IO) phonon modes, the transfer matrix method is employed. The quantized LO and IO phonons fields, as well as their corresponding Fröhlich electron-phonon interaction Hamiltonians, are also derived. Numerical calculations on a four-layer GaAs/Al_xGa_{1-x}As QC have been performed. Results reveal that there are six branches of IO …

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On Hamiltonian Formulation Of Non-Conservative Systems, Eqab M. Rabei, Tareq S. Alhalholy, A. A. Taani Jan 2004

On Hamiltonian Formulation Of Non-Conservative Systems, Eqab M. Rabei, Tareq S. Alhalholy, A. A. Taani

Turkish Journal of Physics

Fractional derivatives are used to construct the Lagrangian and the Hamiltonian formulation for non-conservative systems. To clarify the theory of Riewe two interesting examples are given. The potentials are obtained using the Laplace transform operator for fractional derivatives and the Lagrangian and Hamiltonian formulations are constructed for the two systems. Besides, it is shown that the Hamilton equations of motion are in agreement with the Euler-Lagrange equations for these systems.

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The Hypervirial-Padé Summation Method Applied To The Anharmonic Oscillator, Altuğ Arda Jan 2004

The Hypervirial-Padé Summation Method Applied To The Anharmonic Oscillator, Altuğ Arda

Turkish Journal of Physics

The energy eigenvalues of the anharmonic oscillator characterized by the cubic potential for various eigenstates are determined within the framework of the hypervirial-Padé summation method. For this purpose the E[3, 3] and E[3, 4] Padé approximants are formed to the energy perturbation series and given the energy eigenvalues up to fourth order in terms of the anharmonicity parameter \lambda.

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Development Of An In-Situ Hydrothermal Dissolved Carbon Dioxide Sensor For Hydrothermal Environments, Brooke Love Jan 2004

Development Of An In-Situ Hydrothermal Dissolved Carbon Dioxide Sensor For Hydrothermal Environments, Brooke Love

Link Foundation Ocean Engineering and Instrumentation Fellowship Reports

Hydrothermal systems at mid ocean ridges are a unique environment which connect the mantle, lithosphere, ocean, and biosphere in one complex system. Fluid chemistry is one key tool in understanding this environment, and carbon dioxide is the most abundant gas in these fluids. Its relative abundance and the information it can give about the magmatic activity, which is one of the ultimate drivers of these systems, and other processes, make it an attractive target for development of an in-situ sensor. This work has shown that attenuated total reflection (ATR) is a promising technique for in situ carbon dioxide measurements under …

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Powerful Change Part 2: Reducing The Power Demands Of Mobile Devices, Rajesh Krishna Balan Jan 2004

Powerful Change Part 2: Reducing The Power Demands Of Mobile Devices, Rajesh Krishna Balan

Research Collection School Of Computing and Information Systems

Consumers expect their mobile devices to be small and light, have a decent battery lifetime, and still be powerful enough to run all their desired applications. The need to satisfy such consumer demands has driven mobile-device manufacturers to make products (such as PDAs and cell phones) that match these needs. However, this inevitably requires tradeoffs. Building smaller, lighter devices requires sacrificing the device's battery capacity because battery technology is still fairly dense and heavy, and contributes most of a mobile device's size and weight. But, mobile devices with the required resources to run useful desktop applications need additional battery power …

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A Secure And Privacy Enhanced Location-Based Service Transaction Protocol In Ubiquitous Computing Environment, Konidala Divyan, Robert H. Deng, Jianying Zhou, Kwanjo Kim Jan 2004

A Secure And Privacy Enhanced Location-Based Service Transaction Protocol In Ubiquitous Computing Environment, Konidala Divyan, Robert H. Deng, Jianying Zhou, Kwanjo Kim

Research Collection School Of Computing and Information Systems

Nowadays mobile phones and PDAs are part and parcel of our lives. By carrying a portable mobile device with us all the time we are already living in partial Pervasive Computing Environment (PCE) that is waiting to be exploited very soon. One of the advantages of pervasive computing is that it strongly supports the deployment of Location-Based Service(s) (LBSs). In PCE, there would be many competitive service providers (SPs) trying to sell different or similar LBSs to users. In order to avail a particular service, it becomes very di#cult for a low-computing and resourcepoor mobile device to handle many such …

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