Laurence A. Lewis

Lawrence Livermore National Laboratory

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Daniel C. Clay

University of Pennsylvania

Avi Degani

Tel Aviv University

Tim Hudson

Clark University

Sarah L. Nelson

Duke University

Honglei Zhu

Yellow River Institute of Hydraulic Research

Gert Verstraeten

KU Leuven

Yvan M.J. Dejaegher

Katherine E. Hurst

National Renewable Energy Laboratory

Douglas L. Johnson

Clark University

Roop L. Mahajan

Virginia Tech

Cooperative Institutions

Lawrence Livermore National Laboratory

Clark University

National Institute of Standards and Technology

National Institute of Standards

University of California, Berkeley

University of Colorado Boulder

Duke University

National Renewable Energy Laboratory

Los Alamos National Laboratory

SLAC National Accelerator Laboratory

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The Measurement and Explanation of the Spatial Perception of Africa: A Nigerian Viewpoint

Geografiska Annaler Series B Human Geography (1980)

Laurence A. Lewis Avi Degani Tim Hudson

ABSTRACTCognitive mapping investigations have demonstrated a preoccupation with the ‘developed’ world. Generally they have suffered from the lack of a systematically applicable methodology. In this study, the Nigerian student's mental map of Africa is examined and a straightforward statistical approach to their explanation is offered. Results suggest that information concerning a given nation is conceptualized ordinally as regression analysis utilizing ratio scale data are less effective than when data are grouped using a natural break strategy. In explaining the cognitive patterns of the African countries, population, size, mass-media, location, and historical factors are found to be significant. However, there is evidence that individual perception, at least at the continental scale, is not the result of a few critical factors acting independently, but is a composite of fragmented hits. As many of these bits are highly time dependent, the methodology utilized should permit the development of a larger comparative data base thus facilitating future inquiries into the dynamic nature of cognitive space.

10.1080/04353684.1980.11879452

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Citations (4)

SOME FLUVIAL GEOMORPHIC CHARACTERISTICS OF THE MANATI BASIN, PUERTO RICO

Annals of the Association of American Geographers (1969)

Laurence A. Lewis

ABSTRACT This study analyzes the hydraulic geometry of the Manatí Basin, located in north central Puerto Rico. Measurements of stream width, depth, velocity, and discharge were made at ten different stations along the Río Manatí. At each station and in the downstream direction, the adjustments of stream width, depth, and velocity to stream discharge for the Manatí Basin are found to be adequately expressed by three power equations: w = aQb, d = cQf , and v = kQm. The rates of change, expressed by the values of the exponents, are found to be determined partially by the locations of sites relative to the river control, the cohesion of the channel materials, the roughness of the channels, and the nonuniform velocity distribution within the river. The similarity in the orderly adjustment of the Manatí channels to discharge fluctuations strongly indicates that the geometric and kinematic properties of the Río Manatí are continuously in equilibrium.

Stream power

Cohesion (chemistry)

10.1111/j.1467-8306.1969.tb00671.x

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Citations (20)

THE ADJUSTMENT OF SOME HYDRAULIC VARIABLES AT DISCHARGES LESS THAN ONE CFS∗

The Professional Geographer (1966)

Laurence A. Lewis

10.1111/j.0033-0124.1966.00230.x

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Citations (20)

The Measurement and Explanation of the Spatial Perception of Africa: A Nigerian Viewpoint

Geografiska Annaler Series B Human Geography (1980)

Laurence A. Lewis Avi Degani Tim Hudson

Cognitive mapping investigations have demonstrated a preoccupation with the 'developed' world. Generally they have suffered from the lack of a systematically applicable methodology. In this study, the Nigerian student's mental map of Africa is examined and a straightforward statistical approach to their explanation is offered. Results suggest that information concerning a given nation is conceptualized ordinally as regression analysis utilizing ratio scale data are less effective than when data are grouped using a natural break strategy. In explaining the cognitive patterns of the African countries, population, size, mass-media, location, and historical factors are found to be significant. However, there is evidence that individual perception, at least at the continental scale, is not the result of a few critical factors acting independently, but is a composite of fragmented hits. As many of these bits are highly time dependent, the methodology utilized should permit the development of a larger comparative data base thus facilitating future inquiries into the dynamic nature of cognitive space.

10.2307/490824

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Citations (6)

Le couvert végétal, la pente du champ et la conservation des terres

Daniel C. Clay Laurence A. Lewis

Source

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Slow slope movement in the dry tropics: La Paguera, Puerto Rico

Zeitschrift für Geomorphologie (1975)

Laurence A. Lewis

10.1127/zfg/19/1975/334

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Citations (4)

Land use, soil loss, and sustainable agriculture in Rwanda

Human Ecology (1990)

Daniel C. Clay Laurence A. Lewis

Agricultural land

Peasant

Sustainable land management

10.1007/bf00889179

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Citations (58)

Roots in the African Dust: Sustaining the Sub-Saharan Drylands

Economic Geography (2000)

Laurence A. Lewis Michael Mortimore

10.2307/144394

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Citations (3)

Slow Movement of Earth under Tropical Rain Forest Conditions

Geology (1974)

Laurence A. Lewis

Research Article| January 01, 1974 Slow Movement of Earth under Tropical Rain Forest Conditions Laurence A. Lewis Laurence A. Lewis 1Graduate School of Geography, Clark University, Worcester, Massachusetts 01610 Search for other works by this author on: GSW Google Scholar Author and Article Information Laurence A. Lewis 1Graduate School of Geography, Clark University, Worcester, Massachusetts 01610 Publisher: Geological Society of America First Online: 02 Jun 2017 Online Issn: 1943-2682 Print Issn: 0091-7613 Geological Society of America Geology (1974) 2 (1): 9–10. https://doi.org/10.1130/0091-7613(1974)2<9:SMOEUT>2.0.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Laurence A. Lewis; Slow Movement of Earth under Tropical Rain Forest Conditions. Geology 1974;; 2 (1): 9–10. doi: https://doi.org/10.1130/0091-7613(1974)2<9:SMOEUT>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Measurements of soil creep in El Yunque National Forest, Puerto Rico, indicate that the average rates of soil movement are greater than rates in other forested areas and generally are greater than in other locales. Also, the velocity distribution indicates two zones of maximum movement. This phenomenon is not explained by normal creep behavior. For the wet tropics, theory must include the roles of throughflow and the distribution, of plant roots, as well as the interaction between gravity and the individual expansion and contraction of soil particles. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

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10.1130/0091-7613(1974)2<9:smoeut>2.0.co;2

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Citations (26)

Simulation of Soil Erosion and Sedimentation in Small River Basins

Physical Geography (1980)

Laurence A. Lewis

Potential erosion and sedimentation for three small stream basins near Dodoma, Tan-zania are simulated using SOILCART, a computer program recently developed to assist in the investi-gation of soil erosion problems. Using only widely available generalized data, the predicted values of soil erosion and sedimentation derived from SOILCART compare favorably to measured values which required a 2-year field investigation. Potential areas of high erosion are identified that could be amelio-rated with proper management. The potential use of SOILCART in preliminary evaluation of erosion and sedimentation problems promises useful results, especially in areas where small dams are proposed.

Sedimentation

10.1080/02723646.1980.10642198

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Citations (2)