Physical Sciences and Mathematics Commons^™

Slowstart Congestion Control For Fine-Grained Layered Multicast, Khalid Shaheen

Archived Theses and Dissertations

No abstract provided.

Effects Of A Large Mesospheric Temperature Enhancement On The Hydroxyl Rotational Temperature As Observedfrom The Ground, S. M.L. Melo, R. P. Lowe, W. R. Pendleton Jr., Michael J. Taylor, B. Williams, C. Y. She

All Physics Faculty Publications

The rotational temperature obtained from the rotational population distribution in the bands of the hydroxyl airglow has been shown to be a suitable proxy for the temperature at a height of 87 km [She and Lowe, 1998]. In this paper we examine in detail simultaneous observations on November 2–3, 1997, at Fort Collins, Colorado (41°N, 105°W), with both a sodium temperature lidar and the Coupling, Energetics, and Dynamics of Atmospheric Regions (CEDAR) OH mesospheric temperature mapper during which significant differences between the hydroxyl and lidar temperatures occur. The large differences are associated with a major temperature enhancement in the region …

The Petrology And Geochemistry Of Volcán Huaynaputina, Southern Peru, Steven R. Schubring

All-Inclusive List of Electronic Theses and Dissertations

The 1600 eruption of Vol can Huaynaputina in Southern Peru was one of the largest historic eruptions (VEl 6). The eruption proceeded in three stages containing the same mineral assemblage of plagioclase>homblende>biotite> Fe-Ti oxides±apatite. Differences in crystal content, vesicularity, volatile content, temperature estimates, and the presence of disequilibrium textures have brought into question the petrogenesis of the 1600 eruption products. This work strives to quantify the pre- and syn-eruption magmatic conditions in order to ascertain the petrogenesis of the eruption products. Stage I was less evolved(~ 73% Si02), volatile rich (:S 5.3% H20), crystal poor (17- 26 wt. …

Semiclassical Scattering Of An Electric Dipole Source Inside A Spherical Particle, James A. Lock

Physics Faculty Publications

Semiclassical scattering phenomena appearing in the far-zone scattered intensity of a point source of electromagnetic radiation inside a spherical particle are examined in the context of both ray theory and wave theory, and the evolution of the phenomena is studied as a function of source position. A number of semiclassical effects that do not occur for plane-wave scattering by the sphere appear prominently for scattering by an interior source. These include a series of scattering resonances and a new family of rainbows in regions of otherwise total internal reflection. Diffractive effects accompanying the semiclassical phenomena are also examined. (C) 2001 …

Learning From Linux, Sourav Mukherji

IIMB Management Review

Conventional wisdom on knowledge management deems organisations as essential vehicles for collaborative knowledge creation but here the entire process of knowledge creation takes place outside the boundary of any formal hierarchical organisation, creating a paradox for knowledge management. An attempt is made here to analyse the Linux development process to help resolve this paradox, and in the process, provide some insights Award Winning Student Essay Learning from Linux for organisational knowledge management.

1998 Debris Flows Near The Yakima River, Kittitas County, Washington—Some Geomorphic Implications, Martin R. Kaatz

Geography Faculty Scholarship

The geomorphic consequences of debris flows and their asso- ciated storms have been documented in many parts of the United States. Few, if any, have been studied and documented in central Washington. The importance of recurrent debris flows in sculpting Washington landscapes has not been generally recognized compared to other processes. Arid and semi-arid regions are particularly vulnerable to debris flows triggered by sudden intense thunderstorms. Most such areas are sparsely populated and eyewitnesses are uncommon. By contrast, semi-arid central Washington is relatively well popu- lated, and there are likely to be people who have observed the storms. Such witnesses …

Direct Imaging Of Human Swi/Snf-Remodeled Mono- And Polynucleosomes By Atomic Force Microscopy Employing Carbon Nanotube Tips, Gavin R. Schnitzler, Chin Li Cheung, Jason H. Hafner, Andrew J. Saurin, Robert E. Kingston, Charles M. Lieber

Barry Chin Li Cheung Publications

Chromatin-remodeling complexes alter chromatin structure to facilitate, or in some cases repress, gene expression. Recent studies have suggested two potential pathways by which such regulation might occur. In the first, the remodeling complex repositions nucleosomes along DNA to open or occlude regulatory sites. In the second, the remodeling complex creates an altered dimeric form of the nucleosome that has altered accessibility to transcription factors. The extent of translational repositioning, the structure of the remodeled dimer, and the presence of dimers on remodeled polynucleosomes have been difficult to gauge by biochemical assays. To address these questions, ultrahigh-resolution carbon nanotube tip atomic …

Harmonising Chart And Navigation-Related Information On Ecdis, Lee Alexander

Center for Coastal and Ocean Mapping

ECDIS is a real-time navigation system that integrates a variety of chart and navigation-related information. More than simply a replacement for a paper nautical chart, ECDIS is capable of continuously determining a vessel's position in relation to land, charted objects, aids-to-navigation, and unseen hazards. Increasingly, ECDIS is being used for both navigation and collision-avoidance tasks. There is growing concern about the display of ever-increasing amounts of both chart and navigation-related information. When it comes to using ECDIS, displaying more information is not necessarily better. Too much information (i.e., clutter) may only lead to confusion. In this regard, there is need …

Seafloor Characterization From Spatial Variation Of Multibeam Backscatter Vs. Grazing Angle, Tianhang Hou, Lloyd C. Huff, Yuri Rzhanov, Larry A. Mayer

Center for Coastal and Ocean Mapping

Backscatter vs. grazing angle, which can be extracted from multibeam backscatter data, depend on characteristics of the multibeam system and the angular responses of backscatter that are characteristic of different seafloor properties, such as sediment hardness and roughness. Changes in backscatter vs. grazing angle that are contributed by the multibeam system normally remain fixed over both space and time. Therefore, they can readily be determined and removed from backscatter data. The variation of backscatter vs. grazing angle due to the properties of sediments will vary from location to location, as sediment type changes. The sediment component of variability can be …

Volumes And Areas Of Early Weichselian Ice Dammed Lakes In Northern Russia, Martin Jakobsson, Jan Mangerud, Valery Astakov, John Inge Svendsen

Center for Coastal and Ocean Mapping

No abstract provided.

Improvement To The International Bathymetric Chart Of The Arctic Ocean (Ibcao): Updating The Data Base And The Grid Model, Martin Jakobsson, Norman Cherkis

Center for Coastal and Ocean Mapping

The project to develop the IBCAO grid model was initiated in 1997 with the objective of providing to the Arctic research community an improved portrayal of the seabed north of 64-deg N, in a form suitable for digital manipulation and visualization. The model was constructed from a compilation of all single-beam and multibeam echo soundings that were available for the polar region, complemented where appropriate by newly released contour information. The grid features a cell size of 2.5 x 2.5 km on a polar stereographic projection; it is constructed on the WGS 84 datum, with true scale at 75-deg N. …

Acknowledgements, The Mcnair Team

McNair Scholars Research Journal

No abstract provided.

Full Issue, The Mcnair Team

McNair Scholars Research Journal

No abstract provided.

Eurasian Watermilfoil: Status And Management In Iowa, Gary S. Phillips

Journal of the Iowa Academy of Science: JIAS

In 1993, Eurasian watermilfoil (Myriophyllum spicatum L.) was discovered in Crystal Lake, Hancock County, Iowa. During the next three years, new infestations were discovered by the Iowa Department of Natural Resources (IDNR) fisheries personnel in four Iowa lakes. In July 1996, a program was established by the IDNR to address the threat posed by Eurasian watermilfoil to Iowa's aquatic ecosystems. As part of the Eurasian Watermilfoil Program, statewide aquatic vegetation monitoring was begun to identify those lakes currently infested with Eurasian watermilfoil. Monitoring activities were conducted by IDNR field technicians during the summers of 1996 through 2000. During this time …

Notes From The Director, The Mcnair Team

McNair Scholars Research Journal

No abstract provided.

Fast Implementation Of Depth Contours Using Topological Sweep, Kim Miller, Suneeta Ramaswami, Peter Rousseeuw, Toni Sellarès, Diane Souvaine, Ileana Streinu, Anja Struyf

Computer Science: Faculty Publications

The concept of location depth was introduced in statistics as a way to extend the univariate notion of ranking to a bivariate configuration of data points. It has been used successfully for robust estimation, hypothesis testing, and graphical display. These reguire the computation of depth regions, which form a collection of nested polygons. The center of the deepest region is called the Tukey median. The only available implemented algorithms for the depth contours and the Tukey median are slow, which limits their usefulness. In this paper we describe an optimal algorithm which computes all depth contours in &Ogr;(n 2) time …

Cover - Table Of Contents

Journal of the Iowa Academy of Science: JIAS

No abstract provided.

Front Matter

Journal of the Iowa Academy of Science: JIAS

No abstract provided.

Introduced Fungi: Some Cause Significant Plant Disease Problems, Lois H. Tiffany

Journal of the Iowa Academy of Science: JIAS

Species of the three groups of fungi characterized here on the basis of their energy source acquisition have differing potentials for becoming problem organisms following introduction as alien fungi new to Iowa. The decomposer group of fungi that obtain an energy supply by action of extracellular enzyme activity on dead plant tissues typically have perennial mycelium, are cosmopolitan in distribution, and are unlikely to become problems even if established. The second group, the mycorrhizal/lichen group are highly specific in their relationships. The mycorrhizal fungus group have a potential for being introduced as mycorrhiza already established with the roots of particular …

Iowa's Non-Native Graminoids, Thomas R. Rosburg

Journal of the Iowa Academy of Science: JIAS

Iowa's non-native graminoids include 60 species of grasses and one species of bulrush. The exotic grass species comprise a large proportion (about 31%) of the total species richness of grasses in Iowa, which are second only to the Asteraceae in terms of total species. About half of the non-native graminoids (52%) occur sporadically and form sparse, non-invasive populations, while eighteen species (about 30%) are commonly encountered in large populations throughout the state. About 60% are annuals and a large majority (89%) has been introduced from either Europe or Asia. The C3 photosynthetic pathway is prevalent, occurring in approximately two-thirds of …

Exotic And Invasive Woody Plant Species In Iowa, Donald R. Farrar

Journal of the Iowa Academy of Science: JIAS

Seventy species and hybrids of exotic woody trees, shrubs, and vines have naturalized in Iowa. Nearly half of these species (31) have become invasive pests in parts of the state or have potential do so. Most of the seriously invasive species are spread by bird ingestion of whole fruits. Widespread dispersal by birds hinders eradication efforts and should be considered a trait indicative of potential invasiveness. The economic and ecological values of Iowa forests are seriously compromised by exotic invasive woody species, especially where forests recovering from cropland and pasture are dominated by exotic species. Thus, a simple measure of …

History And Development Of The Eurasian Watermilfoil Program In Iowa, Gary S. Phillips

Journal of the Iowa Academy of Science: JIAS

Following a concerted effort by citizens of the Iowa Great Lakes area to address the threat posed by Eurasian watermilfoil (Myriophyllum spicatum L.) to waterbodies in Iowa, the Iowa Eurasian Watermilfoil Law was passed in 1996 by the Iowa legislature. Passage of this law led to the establishment of the Eurasian Watermilfoil Program in July 1996 to address the requirements specified by this legislation. Since establishment of the Eurasian Watermilfoil Program, numerous activities have been carried out to address the threat posed to aquatic ecosystems by Eurasian watermilfoil. These include public awareness and education, boat access monitoring, aquatic vegetation monitoring, …

Ecological Problems With Iowa's Invasive And Introduced Fishes, Neil P. Bernstein, John R. Olson

Journal of the Iowa Academy of Science: JIAS

Since the time of European settlement, at least 59 non-indigenous fish species have been introduced, reached, or moved within Iowa waters. At least 28 nonnative fish species have been introduced into, or reported from Iowa waters since settlement. Of that number, 10 are established at this time through natural reproduction. In addition, many species of native fishes have been translocated within the state, and we provide documentation for 31 of these species. Two translocated species, gizzard shad (Dorosoma cepedianum) and yellow bass (Marone mississippiensis), have had adverse impacts on Iowa's aquatic ecosystems. While many introductions are thought to be benign, …

Editorial Board & Iowa Academy Of Science Officers And Directors

Journal of the Iowa Academy of Science: JIAS

No abstract provided.

Polariton And Free-Exciton-Like Photoluminescence In Zno, D. C. Reynolds, David C. Look, B. Jogai, T. C. Collins

Physics Faculty Publications

An unusual photoluminescence line X has been observed in ZnO at an energy between that of the common donor-bound excitons (DBEs) and the free excitons (FEs). In the presence of a high carrier concentration, induced by a second below-band gap laser, the DBEs decrease in intensity, due to screening, and both the FEs and X increase. Thus, X has free-exciton, rather than bound-exciton, character. However, its electric-field vector lies in the plane perpendicular to the c axis, as is also found for the DBEs. The appearance of X is discussed in terms of the polariton picture.

Invasive Species In Iowa: An Introduction, James J. Dinsmore, Neil P. Bernstein

Journal of the Iowa Academy of Science: JIAS

Concern over the increasing spread of invasive species and the potential impacts of those species on native communities has been the subject of several books and hundreds of research papers in recent years. President Clinton's Executive Order on invasive species in February1999 raised national attention to this issue. Natural resource agencies have been plagued by an ever-increasing number of invasive species and now consider this issue the second most important problem (after habitat loss) in their fight to maintain some semblance of natural communities on this planet. One group of experts estimated that in the United States alone, invasives cost …

War On Weeds: Winning It For Natural Areas, Jerry E. Asher

Journal of the Iowa Academy of Science: JIAS

I am delighted to be here with you today to discuss the rapidly accelerating damage that invasive exotic plants are inflicting on natural areas in this country. This problem may seem overwhelming, but you need not despair because there are economical, realistic, and effective strategies available to meet this challenge.

There are two purposes to this presentation: to give you information you can use to convince others that invasive exotic plants are seriously harmful, and to suggest that we can win this war on invasive exotic plants if we engage enough of the right people.

An Overview And Management Plan Of Iowa's Non-Native, Invasive, Terrestrial Forbs, Deborah Q. Lewis, Richard O. Pope

Journal of the Iowa Academy of Science: JIAS

Non-native, invasive forb species have been a problem in Iowa since the earliest decades of Iowa's European settlement. The history of studies of Iowa's invasive plants began with L. H. Pammel, and these studies continue to present. Three tables cite the occurrence of many of these species in the state, with Table 1 listing 93 non-native forbs reported by Pammel, Table 2 citing ten invasive forbs of natural areas, and Table 3 adding 38 observed or potential aggressive species of Iowa's anthropogenic and natural areas.

There has been a divergence of interest and research in the management of invasive species …

More Than A Century Of Change In The Ames, Iowa Flora (1859-2000), William R. Norris, Mark P. Widrlechner, Deborah Q. Lewis, Jimmie D. Thompson, Richard O. Pope

Journal of the Iowa Academy of Science: JIAS

We compared two floras compiled in Ames, Iowa: (1) an "historic" flora based on two published floras (1871, 1890) and on 1450 herbarium voucher specimens of plants collected in Ames between 1859 and 1899, and (2) a "current" flora compiled by us during recent fieldwork (1990-2000). Our goals were to determine 1) long-term changes in composition (i.e., the proportion of native species) over time, 2) long-term changes in the abundance of individual plant species over time, and 3) the extent of gains and losses of native and non-native plant species. We found that the proportion of native species declined over …

Purple Loosestrife: History, Management, And Biological Control In Iowa, Amy P. Wiebe, John J. Obrycki

Journal of the Iowa Academy of Science: JIAS

Purple loosestrife (Lythrum salicaria) is an invasive plant species infesting wetlands in North America. Biodiversity and wetland habitat quality are reduced following purple loosestrife establishment. Several management tactics, including cultural, mechanical, and chemical controls, have had limited success in reducing the spread of purple loosestrife. Beginning in the 1990s, a biological control program has introduced several species of natural enemies from Europe that feed on purple loosestrife. Since 1994, Iowa State University has reared and released two species of beetles that feed on purple loosestrife, Galerucella calmariensis and G. pusilla. Biological control is one component of an integrated purple loosestrife …