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Articles 181 - 196 of 196

Full-Text Articles in Physical Sciences and Mathematics

The Jabal Qarah Caves Of The Hofuf Area, Northeastern Saudi Arabia: A Geological Investigation, Nazrul I. Khandaker, Mahbub Hussain, Fadhel Al-Khalifah Oct 2006

The Jabal Qarah Caves Of The Hofuf Area, Northeastern Saudi Arabia: A Geological Investigation, Nazrul I. Khandaker, Mahbub Hussain, Fadhel Al-Khalifah

Publications and Research

The Jabal Al Qarah Caves, located approximately 13 km east of Al Hofuf, Eastern Province of Saudi Arabia, are an intricate cave system developed in the calcareous sandstone, marl and clay of the Upper Miocene to Lower Pliocene Hofuf Formation. Physiographically, the hill of Jabal Al Qarah is an outlier mesa that is located at the eastern edge of the Shedgum Plateau, the southern extension of the As Summan Plateau, and the larger Syrian Plateau to the north. Based on cave morphology and interpreted evolutionary histoty, the Jabal Al Qarah caves appear to be significantly different from other limestone caves …


Modeling And Measuring The Nocturnal Drainage Flow In A High-Elevation, Subalpine Forest With Complex Terrain, Chuixiang Yi, Russell K. Monson, Zhiqiang Zhai, Dean E. Anderson, Brian Lamb, Gene Allwine, Andrew A. Turnipseed, Sean P. Burns Nov 2005

Modeling And Measuring The Nocturnal Drainage Flow In A High-Elevation, Subalpine Forest With Complex Terrain, Chuixiang Yi, Russell K. Monson, Zhiqiang Zhai, Dean E. Anderson, Brian Lamb, Gene Allwine, Andrew A. Turnipseed, Sean P. Burns

Publications and Research

The nocturnal drainage flow of air causes significant uncertainty in ecosystem CO2, H2O, and energy budgets determined with the eddy covariance measurement approach. In this study, we examined the magnitude, nature, and dynamics of the nocturnal drainage flow in a subalpine forest ecosystem with complex terrain. We used an experimental approach involving four towers, each with vertical profiling of wind speed to measure the magnitude of drainage flows and dynamics in their occurrence. We developed an analytical drainage flow model, constrained with measurements of canopy structure and SF6 diffusion, to help us interpret the tower …


Tunnel Geology As Seen By Geologists: Manhattan, New York City, Nazrul I. Khandaker, Stanley Schleifer, Masud Ahmed, Alan R. Slaughter, Belal A. Sayeed, Dorean J. Flores, Mario Jo-Ramirez Oct 2005

Tunnel Geology As Seen By Geologists: Manhattan, New York City, Nazrul I. Khandaker, Stanley Schleifer, Masud Ahmed, Alan R. Slaughter, Belal A. Sayeed, Dorean J. Flores, Mario Jo-Ramirez

Publications and Research

Current exploratory boring operations in and around Manhattan, New York City are providing geologists and geotechnical engineers with a plethora of new and interesting geological information, which has not been previously reported. The rocks encountered, mostly medium to high-grade metamorphic rocks, with both mafic and felsic intrusives, are highly variable in competency and mechanical durability. One of the most frequently encountered rock types is a garnetiferous-muscovite-biotite schist which grades into schistose gneiss and displays a wide variety of structural, compositional, and textural attributes. Metamorphic minerals showing the variable degree of metamorphism include graphite, talc, garnet, kyanite, tourmaline, emory, and occasionally …


A Handheld Polarimeter For Aerosol Remote Sensing, James W. Frost, Fouad Nasraddine, J. Rodriguez, I. Andino, Brian Cairns Sep 2005

A Handheld Polarimeter For Aerosol Remote Sensing, James W. Frost, Fouad Nasraddine, J. Rodriguez, I. Andino, Brian Cairns

Publications and Research

In this paper we show how measurements made by a simple handheld polarimeter in conjunction with automated sunsky radiometers can be used to effectively constrain the real part of the complex refractive index of aerosols. We find that even measurements over a limited angular range near 90° scattering angle are sufficient for this purpose. We also note that because of the effect of surface reflectance on the observed degree of linear polarization (DOLP) it is sensible to select spectral bands for these measurements for which the surface is relatively dark and homogeneous (i.e. wavelengths shorter than 700 nm are to …


Biospeleologists, Aldemaro Romero Jr. Jan 2004

Biospeleologists, Aldemaro Romero Jr.

Publications and Research

No abstract provided.


The Unsung Heroes Of Speleology, Aldemaro Romero Jr., Kathryn Benz Jan 2000

The Unsung Heroes Of Speleology, Aldemaro Romero Jr., Kathryn Benz

Publications and Research

No abstract provided.


Microanalytical Investigations Of Gold-Bearing Rocks From The An Najadi Region In Saudi Arabia, Nazrul I. Khandaker, M. Ahmed, M. M. Hariri, M. A. Garwan, K. R. Khan, M. M. Al-Ohali Jul 1997

Microanalytical Investigations Of Gold-Bearing Rocks From The An Najadi Region In Saudi Arabia, Nazrul I. Khandaker, M. Ahmed, M. M. Hariri, M. A. Garwan, K. R. Khan, M. M. Al-Ohali

Publications and Research

The Proton Induced X-ray Emission technique with a scanning microbeam (micro-PIXE) and Scanning Electron Microscopy (SEM) were employed to study gold-bearing rocks from the An Najadi and adjacent regions situated within the exposed northeastern part of the Arabian Shield. These microanalytical investigations, together with routine petrological and ore microscopic studies, demonstrated the presence of important partitioning of major minerals and trace elements in several samples. These measurements also revealed microstructural features including brecciation within quartz grains and metal concentrations within these fracture-controlled micro-conduits. Results showed promise in terms of using distinctive geochemical signatures for ore body recognition. Of particular interest …


Study Of Volcanic Sediments By Microbeam-Pixe Technique, Nazrul I. Khandaker, M. Ahmed, M. A. Garwan Apr 1996

Study Of Volcanic Sediments By Microbeam-Pixe Technique, Nazrul I. Khandaker, M. Ahmed, M. A. Garwan

Publications and Research

Single mineral grains in a suite of Cretaceous (85–90 Ma) volcanic sedimentary rocks were analyzed using the microbeam-PIXE technique to understand fundamental geological processes responsible for micro-scale variation in elemental composition across mineral zones, twinning, cleavage planes, fractures and grain boundaries. Distributions of major and trace elements show distinct geochemical features indicative of a specific geological setting and a subsequent diagenetic process in these volcanic sediments. Examples of mineral zoning, microstructures of variable chemistry and post-depositional fluid flow are discussed using the data on feldspar group of minerals.


Natural And Technological Disasters: Causes, Effects And Preventive Measures, Nazrul I. Khandaker Jan 1992

Natural And Technological Disasters: Causes, Effects And Preventive Measures, Nazrul I. Khandaker

Publications and Research

No abstract provided.


El Hombre Comenzó A Extinguir Especies Hace 11.000 Años, Aldemaro Romero Jr. Jan 1989

El Hombre Comenzó A Extinguir Especies Hace 11.000 Años, Aldemaro Romero Jr.

Publications and Research

No abstract provided.


Que La Luz De La Sabiduría Ilumine Nuestras Cuevas, Aldemaro Romero Jr. Jan 1985

Que La Luz De La Sabiduría Ilumine Nuestras Cuevas, Aldemaro Romero Jr.

Publications and Research

No abstract provided.


Tarracolimulus Rieki, Nov. Gen., Nov. Sp., Nuevo Limúlido Del Triásico De Montreal – Alcover (Tarragona), Aldemaro Romero Jr., L. Vía Boada Jan 1977

Tarracolimulus Rieki, Nov. Gen., Nov. Sp., Nuevo Limúlido Del Triásico De Montreal – Alcover (Tarragona), Aldemaro Romero Jr., L. Vía Boada

Publications and Research

No abstract provided.


Predicción De Terremotos: ¿Cuándo?, Aldemaro Romero Jr. Jan 1976

Predicción De Terremotos: ¿Cuándo?, Aldemaro Romero Jr.

Publications and Research

No abstract provided.


Descubiertos Restos Recientes De Un Megaterio, Aldemaro Romero Jr. Jan 1975

Descubiertos Restos Recientes De Un Megaterio, Aldemaro Romero Jr.

Publications and Research

No abstract provided.


La Deriva De Los Continentes, Aldemaro Romero Jr. Jan 1974

La Deriva De Los Continentes, Aldemaro Romero Jr.

Publications and Research

No abstract provided.


Los Cañones Submarinos, Aldemaro Romero Jr. Jan 1973

Los Cañones Submarinos, Aldemaro Romero Jr.

Publications and Research

No abstract provided.