Physical Sciences and Mathematics Commons^™

Dynamically Maintained Steady-State Pressure Gradients, D. P. Sheehan

Physics and Biophysics: Faculty Scholarship

In a sealed blackbody cavity with gas, pressure gradients commonly take three forms: (a) statistical fluctuations, (b) transients associated with the system relaxing toward equilibrium, and (c)equilibrium pressure gradients associated with potential gradients (such as with gravity). In this paper, it is shown that in the low-density (collisionless) regime, a fourth type of pressure gradient may arise, this due to steady-state differential thermal desorption of surface species from chemically active surfaces. This gas phase is inherently nonequilibrium in character. Numerical simulations using realistic physical parameters support the possibility of this gas phase and indicate that these novel pressure gradients might …

Four Paradoxes Involving The Second Law Of Thermodynamics, D. P. Sheehan

Physics and Biophysics: Faculty Scholarship

Recently four independent paradoxes have been proposed which appear to challenge the second law of thermodynamics [1-8]. These paradoxes are briefly reviewed. It is shown that each paradox results from a synergism of two broken symmetries - one geometric, one thermodynamic

Analysis Of Hydric Pine Flatwood Ephemeral Pool Macroinvertebrate And Crustacean Assemblages Along A Temporal And Spatial Gradient From A Hypothesized Colonial Source, Henry Leon Griffith

Theses and Dissertations

A survey of the macroinvertebrate and crustacean assemblages in hydric pine flatwood wetlands during fill and drawdown periods was conducted from September to November 1998, in Lee County, Florida. Physical and chemical information, relationships between community composition and physical and chemical conditions were analyzed and a monitoring plan for detecting impacts of declining water supply in hydric pine flatwood communities was proposed. In addition, possible sources of colonists and patterns of community assemblage were investigated. Twelve ephemeral pools and three associated intermittently exposed cypress heads were sampled monthly, over three months, using 1 D-ring benthic sweep, 2 Hester-Dendy multiple plate …

A V And I Ccd Mosaic Survey Of The Ursa Minor Dwarf Spheroidal Galaxy, J. T. Kleyna, M. J. Geller, S. J. Kenyon, M. J. Kurtz, J. R. Thorstensen

Dartmouth Scholarship

We discuss a Johnson-Cousins V- and I-band CCD mosaic survey of the Ursa Minor dwarf spheroidal galaxy (dSph) to V ~ 22. We covered UMi with 27 105 × 105 overlapping CCD frames, each frame consisting of two 300 s exposures in each of V and I. We also observed several regions ~3° from UMi to obtain an estimate of contamination by galaxies and Galactic stars. We report the first H-R diagram of an entire dSph. Separation of dwarf stars from foreground stars by color allows a robust estimation of the structural parameters of UMi. We examine …

An Implementation Of External-Memory Depth-First Search, Christopher S. Leon

Dartmouth College Undergraduate Theses

In many different areas of computing, problems can arise which are too large to fit in main memory. For these problems, the I/O cost of moving data between main memory and secondary storage (for example, disks) becomes a significant bottleneck affecting the performance of the program. Since most algorithms do not take into account the size of main memory, new algorithms have been developed to optimize the number of I/O's performed. This paper details the implementation of one such algorithm, for external-memory depth-first search. Depth-first search is a basic tool for solving many problems in graph theory, and since graph …

The Effects Of Singular Value Decomposition On Collaborative Filtering, Michael H. Pryor

Dartmouth College Undergraduate Theses

As the information on the web increases exponentially, so do the efforts to automatically filter out useless content and to search for interesting content. Through both explicit and implicit actions, users define where their interests lie. Recent efforts have tried to group similar users together in order to better use this data to provide the best overall filtering capabilities to everyone. This thesis discusses ways in which linear algebra, specifically the singular value decomposition, can be used to augment these filtering capabilities to provide better user feedback. The goal is to modify the way users are compared with one another, …

Database Selection Techniques For Routing Bibliographic Queries, Ee Peng Lim, Wee-Keong Ng, Jian Xu, Yinyan Cao

Research Collection School Of Computing and Information Systems

No abstract provided.

Querying Structured Web Resources, Ee Peng Lim, Cheng Hai Tan, Boon Wan Lim, Wee-Keong Ng

Research Collection School Of Computing and Information Systems

To provide query facilities over Web resources, several web search engines such as Yahoo, Altavista, Infoseek, etc. have been developed. Most prominently, web search engines have been used to index all web pages on the Internet. The queries supported by these search engines are mainly designed to reveal web pages that meet the search criteria specified by the users. In this way, the search engines have been used as some kind of discovery tools. The queries supported are known as discovery queries. On the other hand, a web search engine can also be used to index and support queries over …

A Computational Framework For Telemedicine, Ian Foster, Gregor Von Laszewski, Brian Toonen, George K. Thiruvathukal

Computer Science: Faculty Publications and Other Works

Emerging telemedicine applications require the ability to exploit diverse, geographically distributed resources. These applications use high-speed neworks to integrate supercomputers, large databases, archival storage devices, advanced visualization devices, and/or sophisticated instruments. This form of networked virtual supercomputers is also known as metacomputers and is being used by many other scientific applications areas. In this article, we analyze requirements necessary for a telemedicine computing infrastructure and compare them with requirements found in a typical metacomputing environment. We will show that metacomputing environments can be used to enable a more powerful and unified computational infrastructure for telemedicine. The Globus metacomputing environment can …

Singularity Avoidance Strategies For Satellite Mounted Manipulators Using Attitude Control, Nathan A. Titus

Theses and Dissertations

Control concepts for satellite mounted manipulators (SMM) are examined. The primary focus is on base actuated concepts, which eliminate singularity problems associated with free floating SMMs. A new form of the equations of motion for an n-link SMM is developed using a quasi coordinate form of Lagrange's Equation. Alternative free floating SMM designs are presented which eliminate dynamic singularities, but still experience difficulties due to the unactuated base. A new generic SMM controller is developed as a framework for various control concepts with and without base actuation. Momentum constrained Jacobians are shown to produce better SMM tracking than fixed base …

Surface Models Of Finite Geometries, Ramon Manuel Figueroa-Centeno

Dissertations

The standard non-Euclidean geometries, hyperbolic geometry and elliptical geometry, both arise by negating the parallel postulate of Euclid. Both these geometries share with Euclidean geometries an infinitude of points and lines. But also possible are many finite geometries. Among these are the class of projective geometries PG(m,q) of projective dimension m (m > 2) and the k-configurations. These mathematical objects, although primarily geometric in nature, provide related structures of combinatorial interest: block designs. These have applications in scheduling problems and the design of experiments for statistical analysis. Recently, A. T. White has added a topological flavor to the study …

Electron Emission Following The Interaction Of Slow Highly Charged Ions With Solids, Joseph W. Mcdonald

Dissertations

The interaction of highly-charged ions with surfaces involves many excitation processes of the surface atoms and the bulk material. One such process, the emission of electrons from surfaces due to the potential energy of the incident ions has been studied. The experimental results presented here confirm that the majority of electrons emitted as a result of highly-charged ions interacting with a solid surface have energies of about 20 eV. Auger processes contribute a smaller fraction of the total emitted electrons with increasing Z o f the projectile. This contribution to the total electron emission yield is found to be less …

Gps Measurements Athe Northern Caribbean Plate Boundary Zone: Impact Of Postseismic Relaxation Following Historic Earthquakes, Fred F. Pollitz, Timothy H. Dixon

School of Geosciences Faculty and Staff Publications

GPS measurements in the northern Caribbean suggest that the rate of Caribbean plate motion relative to North America is about 10 mm/yr faster than predicted by global plate motion model NUVEL-1A. Several of the key sites used in the GPS study are located in the Dominican Republic, near the rupture zones of large earthquakes in 1946 and in the previous two centuries. Postseismic relaxation of the crust and upper mantle is a possible explanation for the plate velocity discrepancy. We explore a range of fault mechanisms and crustal and mantle rheology to place an upper bound on postseismic relaxation effects. …

Aquila X-1: A Low-Inclination Soft X-Ray Transient, T. Shahbaz, J. R. Thorstensen, P. A. Charles, N. D. Sherman

Dartmouth Scholarship

We have obtained I-band photometry of the neutron star X-ray transient Aql X-1 during quiescence. We find a periodicity at 2.487 cycles d⁻¹, which we interpret as twice the orbital frequency (19.30±0.05 h). Folding the data on the orbital period, we model the light-curve variations as the ellipsoidal modulation of the secondary star. We determine the binary inclination to be 20°–30° (90 per cent confidence) and also determine the 95 per cent upper limits to the radial velocity semi-amplitude and rotational broadening of the secondary star to be 117 and 50 km s⁻¹, respectively.

Location Independent Names For Nomadic Computers, David Steere, Mark Morrissey, Peter Geib, Calton Pu, Jonathan Walpole

Computer Science Faculty Publications and Presentations

Recent advances in the Domain Name System (DNS) and the Dynamic Host Configuration Protocol (DHCP) have enabled a new approach to supporting mobile users: location independent naming. In this approach, machines use the same hostname from any internet location, but use an IP address that corresponds to their current location. We describe a protocol that implements location independent naming for nomadic computers, i.e., machines that do not need transparent mobility. Our protocol allows hosts to move across security domains, uses existing protocols, and preserves existing trust relationships. Therefore, it preserves the performance and security of normal IP for nomadic computers …

A Pilot Study Testing A Proprietary Sealant For Plaque Reduction, Jennifer Rowland

Loma Linda University Electronic Theses, Dissertations & Projects

Enamel demineralization due to increased plaque accumulation is a well-recognized problem associated with fixed orthodontic appliances. The purpose of this study was to evaluate the efficacy of a proprietary product to be marketed by 3M Unitek for the reduction of plaque accumulation and thereby reduce enamel demineralization.

Sixty four bovine teeth were divided equally into an untreated control group and a group treated with the proprietary sealant product. Both groups were subsequently immersed in a Streptococcus mutans culture. Plaque deposits from each group were removed, suspended in trypticase soy broth, serially diluted, and plated on trypticase soy agar at 1, …

Scaled-Energy Floquet Spectroscopy In A Strong Electric Field: A Semiquantal Calculation Of The Recurrence Spectrum, V. Kondratovich, John B. Delos

Arts & Sciences Articles

We consider a hydrogen atom in a strong static electric field with a weak parallel radio-frequency (rf) field. We compute the photoabsorption spectrum by calculating the spectrum of Floquet states, including their quasienergies and their oscillator strengths. Our calculation is based upon “semiquantal” formulas: we calculate the discrete spectrum of quasienergy states by using a quantum adiabatic approximation combined with semiclassical (Bohr-Sommerfeld) quantization rules. We express this spectrum in a manner consistent with the method of scaled-variable spectroscopy, and then calculate the Fourier transform. These calculated absorption spectra and recurrence spectra are in good agreement with experiments on Li atoms. …

Does The Oswestry Or Sf-36 Help A Therapist To Predict Treatment Classification, Amy Crawford, Denese D. Kaufeldt-Soliz

Loma Linda University Electronic Theses, Dissertations & Projects

The purpose of this study was to determine the relationship of two disability questionnaires, the Oswestry Low Back Pain Disability Questionnaire (Oswestry) and the Medical Outcome Study Short Form-36 (SF-36), and a standardized physical examination and diagnostic classification system. The physical examination was performed by the evaluating therapists from the clinic and classification was determined by the evaluating therapists and the investigators to ensure correct subject placement into treatment Stages la, lb, or II. Data collection occurred at an outpatient physical therapy clinic in a metropolitan area health maintenance organization, where a sample of 221 subjects with low back pain …

A Basis Theorem For Perfect Sets, Marcia J. Groszek, Theodore A. Slaman

Dartmouth Scholarship

We show that if there is a nonconstructible real, then every perfect set has a nonconstructible element, answering a question of K. Prikry. This is a specific instance of a more general theorem giving a sufficient condition on a pair M ⊂ N of models of set theory implying that every perfect set in N has an element in N which is not in M.

Perturbed Hamiltonian System Of Two Parameters With Several Turning Points, Myeong Joon Ann

Dissertations

No abstract provided.

Process Lower Deviation Selection Policy For Load Distribution, Louay Farag

Archived Theses and Dissertations

No abstract provided.

A Measurement Of The Inclusive B → Sγ Branching Ratio, R. Barate, Manoj Thulasidas

Research Collection School Of Computing and Information Systems

The avour changing neutral current decay b ! s has been detected in hadronic Z decays collected by ALEPH at LEP. The signal is isolated in lifetime-tagged b b events by the presence of a hard photon associated with a system of high momentum and high rapidity hadrons. The background processes are normalised from the data themselves. The inclusive branching ratio is measured to be (3:11 0:80stat 0:72syst) 104 ; consistent with the Standard Model expectation via penguin processes

Improving Performance By Branch Reordering, Minghui Yang, Gang-Ryung Uh, David B. Whalley

Gang-Ryung Uh

Sediment Control At Water Intakes Along Sand Bed Rivers, Fred L. Ogden

Fred L. Ogden

Results from five physical hydraulic model studies of riverside water intakes situated along the Missouri River reach between Sioux City, Iowa, and St. Louis, Missouri, are presented. Movable-bed, undistorted Froude-scale models are used to determine the effectiveness of structural modifications in the vicinity of the intake to limit the influx of bed-load sediments. Solutions developed in each case include a series of submerged flow-turning vanes located on the riverward side of the intake. A sediment-barrier wall between the vanes and intake ...

The Intelligent Browser For Texpros, Chih-Ying Wang

Dissertations

Browsing is a technique, which helps users to formulate their query and retrieve information in the information retrieval system. This technique provides users with capabilities of understanding their information needs and gaining system knowledge during the course of the browsing and thus it eases the users' burden when issuing queries. The basic components of the browser provides an underlying structure which allows users to navigate and a browsing process controller which provides users with the needed assistance during each browsing session.

In this dissertation, a new infrastructure (OP-Net), transformed from the existing object network is proposed. Each object in the …

Knowledge-Based Document Filing For Texpros, Xien Fan

Dissertations

This dissertation presents a knowledge-based document filing system for TEXPROS. The requirements of a. personal document processing system are investigated. In order for the system to be used in various application domains, a flexible, dynamic modeling approach is employed by getting the user involved in document modeling. The office documents are described using a dual-model which consists of a document type hierarchy and a folder organization. The document type hierarchy is used to capture the layout, logical and conceptual structures of documents. The folder organization, which is defined by the user, emulates the real world structure for organizing and storing …

In Vitro Cytotoxicity Study Of Glutaraldehyde And No-React Treated Bioprosthetic Heart Valves And The Aortic Wall, Roger Ongosi

Theses

Valvular failure due to calcification and leaflet disruption of artificial bioprostheses is still a major concern in valve replacement surgery. Previous studies have shown that Glutaraldehyde, a chemical used in the treatment of artificial valves promotes calcification. In this investigation glutaraldehyde and No-React® treated tissue samples of pericardium, cusp and the aortic wall were tested for cytocompatibility using live mouse fibroblast cultures. The samples were cut into 3 X 3 mm2 washed in phosphate buffered saline solution, transferred into cell culture flask containing cells that had been cultured for 24 hours and incubated at 37 "C in 5 % CO2. …

Does The Tunicate Bostrichobranchus Digonas (Abbott) Control The Seasonal Distribution Of Phytoplankton Biomass In Tampa Bay?, The Bay Study Group Department Of Sanitary Sewers

Reports

This report primarily examines relationships between the tunicate B. digonas and several water quality parameters, with emphasis on chlorophyll-a concentrations, for the period September 1996 through March 1998. This study period encompasses two complete September to March periods which, based on surveys in previous years by the BSG, has proven to be the time of year when hatched stages of the tunicate generally can be expected to be present on the bay bottom. However, the report also examines water quality and tunicate information gathered for several years prior to 1996.

The Importance Of Liability For The Redevelopment Of Brownfields : The Developers View, Daniel F. Chachakis

Theses

The thousands of former industrial properties lying vacant in New Jersey are an economic challenge for all areas of government. If these properties are, or are perceived to be, contaminated then they are labeled Brownfields. An important question is whether the threat of liability for contamination by prior owners is a current cause behind the failure of developers to acquire and redevelop Brownfields in the State of New Jersey.

The goal of this work was to discover if there is a link between liability and the developer's decision making process. How important is the liability factor? Fifty-seven variables were examined …

Incentive Factors That Affect The Redevelopment Of Brownfield Sites In New Jersey, Edison L. Hammond

Theses

This thesis sought to addressthree main questions:

· Are brownfieldsa significant problem in New Jersey and its municipalities?

· What factors havecontributed to brownfields' continued existence?

· What factors aremost important for correcting brownfields in the state?

The study involved surveyingFederal and state agencies, NonGovernmental Organizations (NGOs) andmunicipalities that work with brownfields. It involved a survey questionnaire,followed by a detailed telephone interview to determine municipalities'satisfaction with actions and policies taken by state agencies on brownfieldredevelopment.

Eight Federal and state agenciesand NGOs participated, along with ten municipalities from around thestate. The major findings were: brownfields are a significant problemat all levels; …