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2006

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Articles 4501 - 4530 of 4906

Full-Text Articles in Physical Sciences and Mathematics

Topographic Influence On Overflow Dynamics: Idealized Numerical Simulations And The Faroe Bank Channel Overflow, Tal Ezer Jan 2006

Topographic Influence On Overflow Dynamics: Idealized Numerical Simulations And The Faroe Bank Channel Overflow, Tal Ezer

CCPO Publications

Properties of the North Atlantic Deep Water (NADW) depend on mixing that occurs in the Denmark Strait (DS) and the Faroe Bank Channel (FBC) overflow regions. How the sill's topography in those regions may affect mixing processes and downstream variability is thus investigated using a high-resolution terrain-following ocean model. Model results agree with observations that show enhanced mixing and entrainment downstream from the sill; however, mixing seems to occur over a longer distance downstream from the FBC sill and more abruptly downstream from the DS sill. Sensitivity experiments with various FBC sill widths demonstrate that the narrow sill is responsible …


Ocean Warming And Freshening In The Northern Gulf Of Alaska, Thomas C. Royer, Chester E. Grosch Jan 2006

Ocean Warming And Freshening In The Northern Gulf Of Alaska, Thomas C. Royer, Chester E. Grosch

CCPO Publications

Water column temperatures on the shelf in the northern Gulf of Alaska have increased more than 0.8 degrees C and vertical density stratification has increased since 1970 near Seward, Alaska throughout the 250 m depth. This high latitude marine system has low water temperatures, high rates of precipitation, glacial melting, high wind speeds and high rates of biological productivity. A more than 300 km alongshore shift ( locally westward) of isotherms is suggested. The observations are consistent with a conceptual ocean-atmosphere circulation model that employs coastal freshwater discharge, glacial ablation and wind forcing. Positive regional feedback mechanisms accelerate the discharge …


Vertical Distribution Of Decapod Larvae In The Entrance Of An Equatorward Facing Bay Of Central Chile: Implications For Transport, Beatriz Yannicelli, Leonardo R. Castro, Arnoldo Valle-Levinson, Larry Atkinson, Dante Figueroa Jan 2006

Vertical Distribution Of Decapod Larvae In The Entrance Of An Equatorward Facing Bay Of Central Chile: Implications For Transport, Beatriz Yannicelli, Leonardo R. Castro, Arnoldo Valle-Levinson, Larry Atkinson, Dante Figueroa

CCPO Publications

Two short biophysical surveys were carried out in order to assess how the decapod crustacean larvae vertical distribution and circulation patterns in an equatorward facing embayment (Gulf of Arauco, 37° S; 73° W) influenced larval transport into and out of the Gulf. The embayment is located at the upwelling area of south central Chile and features a deep (60 m) and a shallow (25 m) pathway of communication with the adjacent coastal ocean. Profiles of zooplankton, temperature, salinity, dissolved oxygen and current velocity were measured during a 22-h period at the shallow entrance to the gulf. In addition, three zooplankton …


Inter-Annual Sea Level Variability In The Southern Gulf Of Mexico (1966-1976), David Alberto Salas-De-León, Maria Adela Monreal-Gómez, David Salas-Monreal, Mayra Lorena Riveron-Enzastiga, Norma Leticia Sánchez-Santillan Jan 2006

Inter-Annual Sea Level Variability In The Southern Gulf Of Mexico (1966-1976), David Alberto Salas-De-León, Maria Adela Monreal-Gómez, David Salas-Monreal, Mayra Lorena Riveron-Enzastiga, Norma Leticia Sánchez-Santillan

CCPO Publications

Hourly time series at seven locations throughout the southern Gulf of Mexico were used to calculate the trend and the inter-annual sea level. The sea level series from January 1966 to December 1976 were filtered using a Lanczos low pass filter to remove oscillations with periods smaller than one year. The results revealed a sea level increment of about 1.4 mm yr(-1) from 1966 to 1976 in the southern Gulf of Mexico. The monthly sea level variability obtained after the trends were removed, presented a sea level setup during winter and a sea level depression in summer attributed to seasonal …


A Comparison Of Global Estimates Of Marine Primary Production From Ocean Color, Mary-Elena Carr, Marjorie A. M. Friedrichs, Marjorie Schmeltz, Maki Noguchi Aita, David Antoine, Kevin R. Arrigo, Ichio Asanuma, Oliver Aumont, Richard Barber, Michael Behrenfeld Jan 2006

A Comparison Of Global Estimates Of Marine Primary Production From Ocean Color, Mary-Elena Carr, Marjorie A. M. Friedrichs, Marjorie Schmeltz, Maki Noguchi Aita, David Antoine, Kevin R. Arrigo, Ichio Asanuma, Oliver Aumont, Richard Barber, Michael Behrenfeld

CCPO Publications

The third primary production algorithm round robin (PPARR3) compares output from 24 models that estimate depth-integrated primary production from satellite measurements of ocean color, as well as seven general circulation models (GCMs) coupled with ecosystem or biogeochemical models. Here we compare the global primary production fields corresponding to eight months of 1998 and 1999 as estimated from common input fields of photosynthetically-available radiation (PAR), sea-surface temperature (SST), mixed-layer depth, and chlorophyll concentration. We also quantify the sensitivity of the ocean-color-based models to perturbations in their input variables. The pair-wise correlation between ocean-color models was used to cluster them into groups …


Pelagic Functional Group Modeling: Progress, Challenges And Prospects, Raleigh R. Hood, Edward A. Laws, Robert A. Armstrong, Nicholas R. Bates, Christopher W. Brown, Craig A. Carlson, Fei Chai, Scott C. Doney, Paul G. Falkowski, Richard A. Feely, Marjorie A. M. Friedrichs Jan 2006

Pelagic Functional Group Modeling: Progress, Challenges And Prospects, Raleigh R. Hood, Edward A. Laws, Robert A. Armstrong, Nicholas R. Bates, Christopher W. Brown, Craig A. Carlson, Fei Chai, Scott C. Doney, Paul G. Falkowski, Richard A. Feely, Marjorie A. M. Friedrichs

CCPO Publications

In this paper, we review the state of the art and major challenges in current efforts to incorporate biogeochemical functional groups into models that can be applied on basin-wide and global scales, with an emphasis on models that might ultimately be used to predict how biogeochemical cycles in the ocean will respond to global warming. We define the term "biogeochemical functional group" to refer to groups of organisms that mediate specific chemical reactions in the ocean. Thus, according to this definition, "functional groups" have no phylogenetic meaning-these are composed of many different species with common biogeochemical functions.

Substantial progress has …


Transport Of Antarctic Krill (Euphausia Superba) Across The Scotia Sea. Part Ii: Krill Growth And Survival, Bettina A. Fach, Eileen E. Hofmann, Eugene J. Murphy Jan 2006

Transport Of Antarctic Krill (Euphausia Superba) Across The Scotia Sea. Part Ii: Krill Growth And Survival, Bettina A. Fach, Eileen E. Hofmann, Eugene J. Murphy

CCPO Publications

A time-dependent, size-structured, physiologically based krill growth model was used in conjunction with a circulation model to test the hypothesis that Antarctic krill (Euphausia superba) populations at South Georgia are sustained by import of individuals from upstream regions. Surface phytoplankton concentrations along the simulated drifter trajectories were extracted from historical Coastal Zone Color Scanner (CZCS) measurements and sea ice biota concentrations were calculated from sea ice concentration and extent extracted along drifter trajectories from Special Sensor Microwave/ Imager measurements. As additional food sources, a time series of heterotrophic food was constructed from historical data, and time series of …


University Of Texas At Tyler Catalog, 2006 - 2008, University Of Texas At Tyler Jan 2006

University Of Texas At Tyler Catalog, 2006 - 2008, University Of Texas At Tyler

Catalogs

No abstract provided.


Assessment Of Impacts, Adaptation, And Vulnerability To Climate Change In North Africa: Food Production And Water Resources, Ayman F. Abou-Hadid Jan 2006

Assessment Of Impacts, Adaptation, And Vulnerability To Climate Change In North Africa: Food Production And Water Resources, Ayman F. Abou-Hadid

Morocco, Algeria, Tunisia

The climate change impact, vulnerability, and adaptation of the production of some major food crops and irrigation water requirements in Egypt and Tunisia were analyzed. The evaluation was based on the proposed stakeholder adaptation options with a range of modeling methodologies. The stakeholders engaged in the project represent the small-holder farmers, commercial farmers, and strategic resource managers. Simulation models were used to quantify some of the strategic adaptation options proposed by the stakeholders. The preliminary results show that there is an overall reduction in crop yields under climate change even when adaptation is taken into account. As well as, the …


Observations Of Triboelectric Charging Effects On Langmuir-Type Probes In Dusty Plasma, Aroh Barjatya, Charles M. Swenson Jan 2006

Observations Of Triboelectric Charging Effects On Langmuir-Type Probes In Dusty Plasma, Aroh Barjatya, Charles M. Swenson

Publications

Investigation of Earth’s mesosphere using sounding rockets equipped with a myriad of instruments has been a highly active field in the last 2 decades. This paper presents data from three separate instruments: an RF impedance probe, a DC fixed bias Langmuir probe, and an electric field probe, that were flown on a mesospheric sounding rocket flight investigating the presence of charged dust within and/or around a sporadic metal layer. The combined data set indicates a case of payload surface charging, the causes of which are investigated within this paper. A generic circuit model is developed to analyze payload charging and …


Rocket And Radar Investigation Of Background Electrodynamics And Bottom-Type Scattering Layers At The Onset Of Equatorial Spread F, D. L. Hysell, M. F. Larsen, C. M. Swenson, A. Barjatya, T. F. Wheeler, T. W. Bullett, Et. Al. Jan 2006

Rocket And Radar Investigation Of Background Electrodynamics And Bottom-Type Scattering Layers At The Onset Of Equatorial Spread F, D. L. Hysell, M. F. Larsen, C. M. Swenson, A. Barjatya, T. F. Wheeler, T. W. Bullett, Et. Al.

Publications

Sounding rocket experiments were conducted during the NASA EQUIS II campaign on Kwajalein Atoll designed to elucidate the electrodynamics and layer structure of the postsunset equatorial F region ionosphere prior to the onset of equatorial spread F (ESF). Experiments took place on 7 and 15 August 2004, each comprised of the launch of an instrumented and two chemical release sounding rockets. The instrumented rockets measured plasma number density, vector electric fields, and other parameters to an apogee of about 450 km. The chemical release rockets deployed trails of trimethyl aluminum (TMA) which yielded wind profile measurements. The Altair radar was …


2005 Diamond Lake Submersed Aquatic Vegetation Survey, Mark D. Sytsma, Mary Pfauth Jan 2006

2005 Diamond Lake Submersed Aquatic Vegetation Survey, Mark D. Sytsma, Mary Pfauth

Center for Lakes and Reservoirs Publications and Presentations

Diamond Lake is a large natural lake having a surface area of some 3214 acres (1300.7 hectares) and a maximum depth of 52 feet (15.8 meters). It is located within the Umpqua National Forest in the Southern Cascade Mountains of Oregon, at an elevation of over 5000 feet (>1524 meters). Diamond Lake is a high-use waterbody that supports angling, public campgrounds, recreational boating, swimming, and water skiing. The human activity associated with the lake has been a significant contributor to the economy of southern Oregon since the early part of the twentieth century.

Historically Diamond Lake was fishless but …


Point Of Care Healthcare Quality Control For Patients Using Mobile Devices, Owen Lynch Jan 2006

Point Of Care Healthcare Quality Control For Patients Using Mobile Devices, Owen Lynch

Masters

The advances made in the domain of mobile telecommunications over the last decade offer great potential for developments in many areas. One such area that can benefit from mobile communications is telemedicine, which is the provision of medical assistance, in one form or another, to patients who are geographically separated from the healthcare provider. When a person is ill, individual attention from medical professionals is of the utmost importance until they have returned to full health. However, people who suffer with long term and chronic illnesses may need life long care and often must manage their condition at home. Many …


$H$-Vectors Of Generalized Associahedra And Noncrossing Partitions, Colum Watt, Thomas Brady, Christos A. Athanasiadis, Jon Mccammond Jan 2006

$H$-Vectors Of Generalized Associahedra And Noncrossing Partitions, Colum Watt, Thomas Brady, Christos A. Athanasiadis, Jon Mccammond

Articles

A uniform proof is given that the entries of the $h$-vector of the cluster complex $\Delta (\Phi)$, associated by S. Fomin and A. Zelevinsky to a finite root system $\Phi$, count elements of the lattice $\mathbf{L}$ of noncrossing partitions of corresponding type by rank. Similar interpretations for the $h$-vector of the positive part of $\Delta (\Phi)$ are provided. The proof utilizes the appearance of the complex $\Delta (\Phi)$ in the context of the lattice $\mathbf{L}$ in recent work of two of the authors, as well as an explicit shelling of $\Delta (\Phi)$.


Feature Based And Feature Free Textual Cbr: A Comparison In Spam Filtering, Sarah Jane Delany, Derek Bridge Jan 2006

Feature Based And Feature Free Textual Cbr: A Comparison In Spam Filtering, Sarah Jane Delany, Derek Bridge

Conference papers

Spam filtering is a text classification task to which Case-Based Reasoning (CBR) has been successfully applied. We describe the ECUE system, which classifies emails using a feature-based form of textual CBR. Then, we describe an alternative way to compute the distances between cases in a feature-free fashion, using a distance measure based on text compression. This distance measure has the advantages of having no set-up costs and being resilient to concept drift. We report an empirical comparison, which shows the feature-free approach to be more accurate than the feature-based system. These results are fairly robust over different compression algorithms in …


Proximity In Context: An Empirically Grounded Computational Model Of Proximity For Processing Topological Spatial Expression., John D. Kelleher, Geert-Jan Kruijff, Fintan Costello Jan 2006

Proximity In Context: An Empirically Grounded Computational Model Of Proximity For Processing Topological Spatial Expression., John D. Kelleher, Geert-Jan Kruijff, Fintan Costello

Conference papers

The paper presents a new model for context-dependent interpretation of linguistic expressions about spatial proximity between objects in a natural scene. The paper discusses novel psycholinguistic experimental data that tests and verifies the model. The model has been implemented, and enables a conversational robot to identify objects in a scene through topological spatial relations (e.g. ''X near Y''). The model can help motivate the choice between topological and projective prepositions.


A Computational Model Of The Referential Semantics Of Projective Prepositions, John D. Kelleher, Josef Van Genabith Jan 2006

A Computational Model Of The Referential Semantics Of Projective Prepositions, John D. Kelleher, Josef Van Genabith

Conference papers

In this paper we present a framework for interpreting locative expressions containing the prepositions in front of and behind. These prepositions have different semantics in the viewer-centred and intrinsic frames of reference (Vandeloise, 1991). We define a model of their semantics in each frame of reference. The basis of these models is a novel parameterized continuum function that creates a 3-D spatial template. In the intrinsic frame of reference the origin used by the continuum function is assumed to be known a priori and object occlusion does not impact on the applicability rating of a point in the spatial template. …


Activist Training In The Academy: Developing A Master's Program In Environmental Advocacy And Organizing At Antioch New England Graduate School, Steve Chase Jan 2006

Activist Training In The Academy: Developing A Master's Program In Environmental Advocacy And Organizing At Antioch New England Graduate School, Steve Chase

Antioch University Dissertations & Theses

This curriculum action research study begins by raising the question of whether environmental studies programs within higher education should launch activist training programs for public interest advocates and grassroots organizers working for nonprofit organizations focused on environmental protection, corporate accountability, and social justice. Answering that question in the affirmative, the study then focuses on the theoretical issues underlying the creation of activist training programs within the academy, specifically within environmental studies programs, and reports on a case study of the successful development of a master’s program in Environmental Advocacy and Organizing. The first section on theoretical issues focuses first on …


A Study Of Environmental Justice In Relation To Air Pollution And Income, Christian A. Malveaux Jan 2006

A Study Of Environmental Justice In Relation To Air Pollution And Income, Christian A. Malveaux

UNLV Theses, Dissertations, Professional Papers, and Capstones

The purpose of this paper is come to a conclusion on whether or not air pollution and income levels are connected. There is an ongoing pollution problem in Las Vegas. The question that will be attempted to answer in this is paper is: Is there a difference in the amount of air pollution in affluent parts of the Las Vegas Valley and the less affluent parts of the valley? Information and data regarding air pollution is gathered from the Clark County website and other literature. Information on income levels is gathered from journals and literature pertinent to the subject and …


Traveling Waves In A Suspension Bridge System, Robert A. Ain Jan 2006

Traveling Waves In A Suspension Bridge System, Robert A. Ain

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this thesis, we study the traveling waves in a Lazer-McKenna suspension bridge system which is governed by two coupled nonlinear beam and wave equations. The Lazer-McKenna suspension bridge system describes the vertical deflections in the roadbed and supporting cable of a suspension bridge. Based on some basic analysis on the system, we are able to compute traveling waves numerically by using MAPLE. Multiple large-amplitude traveling waves are obtained. The graphs of various traveling waves are displayed and discussed.


Interface Design Requirements For Playing Pong With A Single Switch Device, Brian Mac Namee, John Gilligan Jan 2006

Interface Design Requirements For Playing Pong With A Single Switch Device, Brian Mac Namee, John Gilligan

Conference papers

Motivated by a desire for increased accessibility in digital games, in this paper we consider the design requirements for an interface to a variation of the game Pong for single-switch users. We consider the issues in the design of accessible interfaces for games and propose a set of interface configurations for playing Pong, using this as a proof of concept for more elaborate games.


Studies On 2-Ethyl-3-Carbmethoxy-4-Aryl-5-Oxo-1,4,5,6,7,8-Hexahydroquinoline Derivatives And Calcium Modulatory Activities, Ci̇hat Şafak, Elvan Doğan, Kevser Erol Jan 2006

Studies On 2-Ethyl-3-Carbmethoxy-4-Aryl-5-Oxo-1,4,5,6,7,8-Hexahydroquinoline Derivatives And Calcium Modulatory Activities, Ci̇hat Şafak, Elvan Doğan, Kevser Erol

Turkish Journal of Chemistry

Twelve new compounds having a 2-ethyl-3-carbmethoxy-4-aryl-5-oxo-1,4,5,6,7,8-hexahydroquinoline structure were synthesized, characterized and screened for their calcium modulatory activities. The calcium antagonistic activities of the compounds were investigated by tests performed on isolated rat ileum and lamb carotid artery. Compounds 1, 4, 8 and 9 showed considerable activity.


Synthesis And Characterization Of Metal Complexes Of Cu(Ii), Ni(Ii), Zn(Ii), Co(Ii), Mn(Ii) And Cd(Ii) With Tetradentate Schiff Bases, Jianning Liu, Bo-Wan Wu, Bing Zhang, Yongchun Liu Jan 2006

Synthesis And Characterization Of Metal Complexes Of Cu(Ii), Ni(Ii), Zn(Ii), Co(Ii), Mn(Ii) And Cd(Ii) With Tetradentate Schiff Bases, Jianning Liu, Bo-Wan Wu, Bing Zhang, Yongchun Liu

Turkish Journal of Chemistry

4-(Benzeneazo)salicylaldehyde was synthesized with aniline, sodium nitrite and salicylaldehyde. Two tetradentate ligands, N,N'-bis[4-(benzeneazo) salicylaldehyde]-o-phenylenediamine (H_2L) and N,N'-bis[4-(benzeneazo) salicylaldehyde]ethylenediamine (H_2L') were formed by the 2:1 molar condensation of 4-(benzeneazo) salicylaldehyde with o-phenylenediamine or ethylenediamine. Their Cu(II), Ni(II), Zn(II), Co(II), Mn(II) and Cd(II) complexes were synthesized and characterized by elemental analysis, molar conductivity measurements, and infrared and electronic spectral data. Two ligands and their Ni(II) and Zn(II) complexes were further identified using ^1H NMR spectra. The results suggest that the metal is bonded to the ligand through the phenolic oxygen and the imino nitrogen.


The Impact Of Polyacrylamide Molecular Weight On Its Adsorption Behavior At The Gold/Acidic Solution Interface, Dragica B. Chamovska, Toma P. Grchev, Maja V. Cvetkovska Jan 2006

The Impact Of Polyacrylamide Molecular Weight On Its Adsorption Behavior At The Gold/Acidic Solution Interface, Dragica B. Chamovska, Toma P. Grchev, Maja V. Cvetkovska

Turkish Journal of Chemistry

Adsorption isotherms for polyacrylamide (PAA) on polycrystalline gold, from sulfuric acid (potential range 0-2.0 V/she; 293 K), were obtained by means of cyclic voltammetry with simultaneous monitoring of the double-layer capacity. The Frumkin isotherm indicates that relatively strong attractive forces are present (a = 0.8-1.0), and the Gibbs energies range between 43 and 56 kJ mol^{-1}. The coverage (\theta) of the metal surface with polymer molecules depends on the molar concentration of PAA, as well as on its molecular weight, and the size of the statistical polymer coil in the solution (R_G = 7.49 \times 10^{-3} \times M_n^{0.64}/nm). The adsorption …


Electronic And Optical Processes In Fullerene Films, Naomi Brant Jan 2006

Electronic And Optical Processes In Fullerene Films, Naomi Brant

Masters

This work primarily focuses on the archetypal fullerene, which is C60. C60 is electron rich and yet can be six fold reduced, taking on up to six additional electrons. Interest in the electrical properties of the solid state C60 were intensified when it was observed that it could be chemically doped with alkali metals, producing a metallic state A1C60, and even a superconducting state A3C60, where A indicates an alkali metal such as potassium or rubidium. Previous work has demonstrated that such a conductive state can also be achieved by optical pumping or by electron injection. The electronic properties of …


An Implementation Of The It Fundamentals Knowledge Area In An Introductory It Course, Cheryl L. Aasheim, Choong Kwon Lee, Han Reichgelt Jan 2006

An Implementation Of The It Fundamentals Knowledge Area In An Introductory It Course, Cheryl L. Aasheim, Choong Kwon Lee, Han Reichgelt

Computing: Faculty Publications

The recently promulgated IT model curriculum contains IT fundamentals (ITF) as one of its knowledge areas. It is intended to give students a broad understanding of (1) the IT profession and the skills that students must develop to become successful IT professionals and (2) the academic discipline of IT and its relationship to other disciplines. The model curriculum recommends 33 lecture hours to complete the IT fundamentals knowledge. The model curriculum also recommends that the material relevant to the IT fundamentals knowledge area be offered early in the curriculum, for example in an Introduction to IT course; however, many institutions …


Base-Level Buffers And Buttresses: A Model For Upstream Versus Downstream Control On Fluvial Geometry And Architecture Within Sequences, John M. Holbrook, Robert W. Scott, Francisca Oboh-Ikuenobe Jan 2006

Base-Level Buffers And Buttresses: A Model For Upstream Versus Downstream Control On Fluvial Geometry And Architecture Within Sequences, John M. Holbrook, Robert W. Scott, Francisca Oboh-Ikuenobe

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

The effects of downstream base-level control on fluvial architecture and geometry are well explored in several broadly similar sequence-stratigraphic models. Cretaceous Dakota Group strata, U.S. Western Interior, have characteristics reflecting combined downstream and upstream base-level controls that these models cannot address. Particularly, three layers of amalgamated channel-belt sandstone within this group thicken and are continuous for distances (≤ 300 km) along dip that stretch the reasonable lengths for which these models are intended to apply. As well, architecture in up-dip reaches records repeated valley-scale cut-and-fill cycles. This contrasts with equivalent strata down dip which record channel-scale lateral migration with no …


Ionization Of Atoms With Spin Polarized Electrons, J. Lower, S. Bellm, R. Panajotovic, E. Weigold, A. Prideaux, Z. Stegen, Don H. Madison, Colm T. Whelan, B. Lohmann Jan 2006

Ionization Of Atoms With Spin Polarized Electrons, J. Lower, S. Bellm, R. Panajotovic, E. Weigold, A. Prideaux, Z. Stegen, Don H. Madison, Colm T. Whelan, B. Lohmann

Physics Faculty Research & Creative Works

The most detailed insight into the process of electron impact-induced ionization of atomic species is provided by measurements in which both kinematical and quantum mechanical variables are determined. Here we describe recent (e,2e) experimental and theoretical studies involving the ionization of xenon and argon by spin-polarized electrons in which the fine-structure levels of the ion are energetically resolved. Such investigations shed light on the mechanisms driving the ionization reaction and the role of exchange and relativistic processes.


Measurement Of The High-Field Q Drop In The Tm₀₁₀ And Te₀₁₁ Modes In A Niobium Cavity, Gianluigi Ciovati, Peter Kneisel Jan 2006

Measurement Of The High-Field Q Drop In The Tm₀₁₀ And Te₀₁₁ Modes In A Niobium Cavity, Gianluigi Ciovati, Peter Kneisel

Physics Faculty Publications

In the last few years superconducting radio-frequency (rf) cavities made of high-purity (residual resistivity ratio >200) niobium achieved accelerating gradients close to the theoretical limits. An obstacle towards achieving reproducibly higher fields is represented by “anomalous” losses causing a sharp degradation of the cavity quality factor when the peak surface magnetic field (Bp) is above about 90 mT, in the absence of field emission. This effect, called “Q drop” has been measured in many laboratories with single- and multicell cavities mainly in the gigahertz range. In addition, a low-temperature (100–140 °C) “in situ” baking of the cavity was found …


Effects Of Medicinal Plants On Lead Induced Toxicity Of Biotransformation And Redox Cycling Enzymes, Yusra Saif Khalfan Al Dhaheri Jan 2006

Effects Of Medicinal Plants On Lead Induced Toxicity Of Biotransformation And Redox Cycling Enzymes, Yusra Saif Khalfan Al Dhaheri

Theses

All organisms including humans are constantly and unavoidably exposed to foreign chemicals (xenobiotics), which include both manufactured and natural molecules such as pollutants and plant metabolites. One such alarming pollutant is lead as it is constantly produced from automobiles exhaust products and food containers. It has been documented that lead, as the major heavy metal pollutant in the air, has notable effects on nervous systems and efficiency of several enzymes.

There are some natural products such as medicinal plants that might have antagonistic effects against such pollutants. Several medicinal plants are used as traditional remedies for many ailments without knowing …