Physical Sciences and Mathematics Commons^™

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 …

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 …

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.

The State Of Eritrea Ministry Of Land, Water And Environment, Department Of Environment, Eritrea

East Africa

It is widely agreed today that anthropogenic greenhouse gas (GHG) concentrations in the atmosphere is creating imbalances in the natural cycle of the earth’s climate, best known as climate change. Scientific evidence has shown that the earth has been increasingly getting warmer and warmer. Nine of the ten warmest years, for example, have occurred since 1990. The resultant global change of climate has been of major concern to the international community and the adoption of the United Nations Framework Convention on Climate Change (UNFCCC) in 1992 at the Earth Summit held in Rio de Janeiro, Brazil, was a big step …

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.

The Prairie Naturalist Volume 33, No.4 December 2001

The Prairie Naturalist

SPECIES, SEASON, AND DENSITY OF BURIED SEEDS SURVIVING FOX SQUIRREL DEPREDATION ▪ C. C. Smith, and J. M. Briggs

RELATI0NSHIP OF HYDROLOGICAL CONDITIONS AND POPULATlONS OF BREEDING PIPING PLOVERS ▪ D. S. Licht,

DEMODICOSIS IN A WHITE-TAILED DEER (ODOCOILEUS VIRGINIANUS) IN SOUTH DAKOTA ▪ C. N. Jacques, J. A Jenks. M. B. Hildreth. R. J. Schauer, and D. D. Johnson

SURVEYS OF CALLING AMPHIBIANS IN NORTH DAKOTA ▪ D. H. Johnson, and R. D. Batie

EFFECTS OF HUMAN PRESENCE ON VOCALIZATIONS OF GRASSLAND BIRDS IN KANSAS ▪ S. L Bye, R. J. Robel, and K. E. Kemp

Reviewers 2001

Author …

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 …

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, …

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 …

Forest Invasives In Iowa: Current Problems And Future Issues, John Walkowiak, John Haanstad

Journal of the Iowa Academy of Science: JIAS

Iowa's forest resources of primarily deciduous trees covers over 0.8 million hectares (2 million acres) of upland and floodplain sites too steep or too wet for traditional row crop agriculture. These limited natural forests along with urban trees and shelterbelts plantings of trees are critical for environmental and economic enhancement in the state. Although not yet established in the state, exotic insects, such as gypsy moth, Asian longhorned beetle, and pine shoot beetle, threaten native tree vitality. Established exotic diseases such as oak wilt and Dutch elm disease continue to plague the survival of Iowa's oak and elm resources, respectively. …

Non-Native Amphibians And Reptiles In Iowa, James L. Christiansen

Journal of the Iowa Academy of Science: JIAS

Only a few species appear as introductions into Iowa in the last 30 years. The bullfrog, Rana catesbeiana, was systematically introduced along with fish stocked from hatcheries in the 1930s and this species continues to spread in northern Iowa where it poses a hazard to smaller frogs. Turtles sold as pets, primarily map turtles (Graptemys pseudogeographica and G. geographica) and red-eared turtles (Trachemys scripta) continue to be found in scattered ponds, usually rural, throughout the state. The eastern box turtle (Terrapene carolma) has been reported in or on the edge of most major Iowa cities even though no breeding population …

Index For The Journal Of The Iowa Academy Of Science Volume 108 And Erratum

Journal of the Iowa Academy of Science: JIAS

No abstract provided.

Back Cover

Journal of the Iowa Academy of Science: JIAS

No abstract provided.

Techniques For The Regeneration Of Wideband Speech From Narrowband Speech, Jason A. Fuemmeler, Russell C. Hardie, William R. Gardner

Electrical and Computer Engineering Faculty Publications

This paper addresses the problem of reconstructing wideband speech signals from observed narrowband speech signals. The goal of this work is to improve the perceived quality of speech signals which have been transmitted through narrowband channels or degraded during acquisition. We describe a system, based on linear predictive coding, for estimating wideband speech from narrowband. This system employs both previously identified and novel techniques. Experimental results are provided in order to illustrate the system’s ability to improve speech quality. Both objective and subjective criteria are used to evaluate the quality of the processed speech signals.

Large Nondipole Effects In The Angular Distributions Of K-Shell Photoelectrons From Molecular Nitrogen, Oliver Hemmers, H. Wang, P. Focke, I. A. Sellin, Dennis W. Lindle, J. C. Arce, J. A. Sheehy, P. W. Langhoff

Environmental Studies Faculty Publications

Measurements of angular distributions of K-shell electrons photoejected from molecular nitrogen are reported which reveal large deviations at relatively low photon energies ( ħω≤500eV) from emission patterns anticipated from the dipole approximation to interactions between radiation and matter. A concomitant theoretical analysis incorporating the effects of electromagnetic retardation attributes the observed large nondipole behaviors in N₂ to bond-length-dependent terms in the E1⊗(E2,M1) photoelectron emission amplitudes which are indicative of a potentially universal nondipole behavior in molecular photoionization.

Inside Unlv, Diane Russell, Jennifer Vaughan, Richard Jensen, Mae Worthey-Flennoy

Inside UNLV

No abstract provided.

Discrete Maximum Principle For Nonsmooth Optimal Control Problems With Delays, Boris S. Mordukhovich, Ilya Shvartsman

Mathematics Research Reports

We consider optimal control problems for discrete-time systems with delays. The main goal is to derive necessary optimality conditions of the discrete maximum principle type in the case of nonsmooth minimizing functions. We obtain two independent forms of the discrete maximum principle with transversality conditions described in terms of subdifferentials and superdifferentials, respectively. The superdifferential form is new even for non-delayed systems and may be essentially stronger than a more conventional subdifferential form in some situations.

Computer Sound Card Assisted Measurements Of The Acoustic Doppler Effect For Accelerated And Unaccelerated Sound Sources, Thomas J. Bensky, S. E. Frey

Physics

An approach to experimentally measuring the speed of a moving object by direct application of the Doppler effect for sound is discussed. The method presented here uses a Windows computer and sound card to record Doppler shifted sound from a moving source. This sound card approach allows for direct acquisition of Doppler shifted sound intensity as a function of time, affording much analytical and pedagogical freedom in undergraduate lab instruction. In addition, the acquisition of such data allows for the experimental study of not only constant velocity sound sources, but of accelerated sound sources as well.