Open Access. Powered by Scholars. Published by Universities.®
- Institution
-
- Utah State University (2708)
- TÜBİTAK (1669)
- Morehead State University (1585)
- Washington University in St. Louis (1122)
- Marquette University (1009)
-
- University of Nebraska - Lincoln (932)
- University of New Mexico (792)
- University of South Carolina (720)
- California Polytechnic State University, San Luis Obispo (714)
- Portland State University (680)
- University of Texas Rio Grande Valley (611)
- University of Montana (602)
- City University of New York (CUNY) (570)
- Nova Southeastern University (558)
- Brigham Young University (549)
- Old Dominion University (525)
- Eastern Illinois University (506)
- The Texas Medical Center Library (501)
- Wright State University (467)
- Western Kentucky University (434)
- Loyola University Chicago (414)
- University of Richmond (400)
- Missouri University of Science and Technology (392)
- Boise State University (389)
- University of Kentucky (387)
- University of Central Florida (380)
- Montclair State University (369)
- University of South Florida (361)
- Smith College (338)
- Virginia Commonwealth University (322)
- Keyword
-
- Biology (1042)
- Animals (356)
- Ecology (356)
- Evolution (355)
- Climate change (331)
-
- Biological Sciences (297)
- Department of Biological Sciences (271)
- Cancer (257)
- Conservation (257)
- Scanning electron microscopy (257)
- Humans (243)
- Genetics (236)
- Bacteria (207)
- Mice (202)
- Biodiversity (200)
- Metabolism (193)
- Apoptosis (192)
- Gene expression (181)
- Behavior (174)
- Morphology (169)
- Fish (164)
- Phylogeny (163)
- Biological sciences (160)
- Genomics (160)
- Bioinformatics (159)
- Drosophila (159)
- Invasive species (156)
- Mitochondria (149)
- Development (143)
- Temperature (143)
- Publication Year
- Publication
-
- Turkish Journal of Biology (1669)
- Roger W. Barbour Slide Collection (1387)
- Biology Faculty Publications (1360)
- Biological Sciences Faculty Publications (1155)
- Scanning Microscopy (1089)
-
- Theses and Dissertations (868)
- Arts & Sciences Graduate Student Theses and Dissertations (834)
- Biological Sciences Faculty Research and Publications (749)
- Faculty Publications (745)
- Biology Faculty Publications and Presentations (656)
- School of Biological Sciences: Faculty Publications (649)
- Electronic Theses and Dissertations (645)
- Biology ETDs (639)
- Biological Sciences (625)
- Master's Theses (519)
- Honors Theses (498)
- Masters Theses (496)
- Biology Faculty Works (397)
- Biology Faculty Research (396)
- Biology (377)
- School of Integrative Biological & Chemical Sciences (Formerly Dept. of Biology) (368)
- Dissertations and Theses (367)
- Faculty, Staff and Students Publications (357)
- Faculty Research & Creative Activity (337)
- All Graduate Theses and Dissertations, Spring 1920 to Summer 2023 (333)
- Biological Sciences: Faculty Publications (314)
- Scanning Electron Microscopy (289)
- Journal of Undergraduate Research (283)
- Dissertations (266)
- Karbala International Journal of Modern Science (255)
- Publication Type
Articles 38221 - 38250 of 39279
Full-Text Articles in Entire DC Network
Agonistic Behavior And Dominance In Townsend's Chipmunks (Eutamias Townsendii), Paul Evan Sherman
Agonistic Behavior And Dominance In Townsend's Chipmunks (Eutamias Townsendii), Paul Evan Sherman
Dissertations and Theses
Agonistic behavior and dominance are described for captive Townsend's chipmunks (Eutamias townsendii). A total of 10,739 encounters was recorded; 6441 (59.9%) were agonistic. Chases (58.5%) and displacements (30.8%) were the predominant agonistic behaviors; threats (6.8%) and fights (4.l%) were relatively rare.
Stable, non-triangular hierarchies were rapidly established in 11 of the 12 groups of chipmunks observed; the presence of individuals of equal rank in some groups precluded strict linearity. Dominance positions did not change within a group, but reversals in rank and changes from equal to dominant-subordinate relationships occurred when the membership of groups was changed. One hierarchy …
Life Cycle, Additions To Biology, And New Hosts Of Apophallus Donicus (Trematoda: Heterophyidae) In Oregon, Delbert Niemi
Life Cycle, Additions To Biology, And New Hosts Of Apophallus Donicus (Trematoda: Heterophyidae) In Oregon, Delbert Niemi
Dissertations and Theses
Apophallus donicus is examined, its life cycle is described, and certain additions are made to its biology.
It is thought, but not proven, that eggs are eaten by the first intermediate host, the local stream snail Flumenicola virens, and the miracidia escape internally. Mother and daughter rediae stages result, the later producing cercariae which are shed into the water. After burrowing just beneath the skin in suckers (Catostomus macrocheilus Girard), rainbow trout (Salmo gairdneri Richardson), coho salmon (Oncorhynchus kisutch (Walbaum)), squawfish (Ptychocheilus oregonensis Richardson), blackside dace (Rhinichthys osculus nubilus (Girard)), redside shiners (Richardsonius …
Cytogenetic Effects Of Vitavax Fungicide On Secale Cereale On Allium Cepa, Jack Ernest Staub
Cytogenetic Effects Of Vitavax Fungicide On Secale Cereale On Allium Cepa, Jack Ernest Staub
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
The effects of Vitavax fungicide (2,3-dihydro-5-carboxanilido-6-methyl-1,4-oxathiin) on meiotic chromosomes of rye (Secale cereale) and mitotic chromosomes of onion (Allium cepa) and rye were observed.
The principal aberrations recorded in pollen mother cells of rye were: 1-4 univalents at metaphase I; sticky bridges at telophase I; and micronuclei and misshapen nuclei at the quartet stage.
The principal aberrations recorded in root tip mitoses in onion and rye were: chromosome fragmentation, disintegration, clumping, aggregation and inhibition of mitosis.
All meiotic phases were significantly affected by 1,000, 5,000,10,000, 33,300, 66,600 ppm Vitavax at the 48, 72, and 96 hour …
Regulation Of Rabbit Testicular Capsular Motility: Prostaglandins, Sex Steroids, And Sympathomimetic Agents, Rod R. Seeley
Regulation Of Rabbit Testicular Capsular Motility: Prostaglandins, Sex Steroids, And Sympathomimetic Agents, Rod R. Seeley
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
Smooth-muscle active compounds were extracted from rat and rabbit testicular homogenates, and from bathing media of rabbit testicular capsular preparations and were tentatively characterized as prostaglandins. The endogenous prostaglandins were responsible for spontaneous testicular capsular contractions in vitro, but were not solely responsible for spontaneous testicular capsular motility in vivo. In this respect, significantly greater concentrations of prostaglandins were extracted from bathing media from spontaneously contracting capsules in vitro than from inactive capsules in vitro or spontaneously contracting capsules in vivo. No significant difference was observed in the amount of prostaglandin extracted from the bathing media of …
Studies On Some Bacteriolytic Bacteria Isolated From An Oxidation Pond, Paul Christian Radich
Studies On Some Bacteriolytic Bacteria Isolated From An Oxidation Pond, Paul Christian Radich
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
During bacteriological studies of the Logan City Sewage Oxidation Ponds, Logan, Utah, a group of bacteria was discovered which could lyse killed cells of Escherichia coli. The present research effort was an attempt to determine whether two isolates from this earlier study might play a role in the reduction of coliforms and other bacteria in the oxidation ponds. It was also desired to characterize partially the lytic enzymes produced by the two isolates and to determine as far as possible the organisms' identity.
Both isolates were Gram negative rod-shaped organisms with a single polar flagellum. On Cytophaga agar they …
Biology Of Mimulus Guttatus In Thermal Areas In Yellowstone National Park, Wyoming, Barbara Rice
Biology Of Mimulus Guttatus In Thermal Areas In Yellowstone National Park, Wyoming, Barbara Rice
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
Mimulus guttatus populations in Yellowstone Park were studied in relation to their thermal habitat. Thermal areas have an extra-solar heat source, and are not snow covered in winter. Snow depth on adjacent non thermal soils may exceed 1 meter. The hypothesis that these populations have formed a distinct high temperature tolerant race was tested.
Thermal populations form two categories, based on habitat type: plants on sinter and plants in boggy areas. Plants growing on sinter are dwarfed, with an average height of 5.6 ±. 2.2 cm. They are facultative annuals which germinate in the fall, overwinter as rosettes, and flower …
Incorporation Of Protoporphyrin Ix Into Chlorophyll A And Purification And Properties Of (-) S-Adenosyl-L-Methionine-Magnesium Protoporphyrin Ix Methyltransferase, Jii Shieh
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
Experiments on the incorporation of 14C-protoporphyrin IX into chlorophyll indicate that ferrous iron may be involved in reactions between protoporphyrin IX and chlorophyll. Experiments using both health and chlorotic tobacco tissue for incorporation studies show that incorporation of protoporphyrin IX into chlorophyll was activated by Fe2+.
S-adenosylmethionine-magnesium protoporphyrin IX methyltransferase (E.C.2.1.1.11) which catalyzes the reaction between S-adenosylmethionine and Mg protoporphyrin IX to form S-adenosylhomocysteine and Mg protoporphyrin IX monomethyl ester was demonstrated in barley seedlings. Methyltransferase was found principally in whole chloroplasts and fractions containing mitochondria were disintegrated chloroplasts. Use of detergent Tween 80, precipitation with protamine …
The Effects Of Water Extracts From Juglans Nigra L. On The Germination Of Native Deciduous Tree Species, Orman W. Conrad Jr.
The Effects Of Water Extracts From Juglans Nigra L. On The Germination Of Native Deciduous Tree Species, Orman W. Conrad Jr.
Morehead State Theses and Dissertations
A thesis presented to the faculty of the School of Sciences and Mathematics at Morehead State University in partial fulfillment of the requirements for the Degree of Master of Science in Biology by Orman W. Conrad, Jr. on April 30, 1973.
The Effects Of Chlordane On Pregnant Mice And Their Offspring, Timothy W. Leonard
The Effects Of Chlordane On Pregnant Mice And Their Offspring, Timothy W. Leonard
Morehead State Theses and Dissertations
A thesis presented to the faculty of the School of Sciences and Mathematics at Morehead State University in partial fulfillment of the requirements for the Degree of Master of Science in Biology by Timothy W. Leonard on April 27, 1973.
Ecology Of The Arroyo Hondo Pueblo Site, Nathan Edmund Kelley
Ecology Of The Arroyo Hondo Pueblo Site, Nathan Edmund Kelley
Biology ETDs
This ecological study is one part of a major archaeological investigation which began in the summer, 1970. The excavation of the pueblo ruins (Laboratory of Anthropology Site 12) southeast of Santa Fe, New Mexico, is under the supervision of Dr. Douglas Schwartz, Director of the School of American Research, and is supported primarily by a grant from the National Science Foundation (grant no. GS28001X2). The objective of the study was to determine those present environmental qualities which would support or affect in some manner a primitive agricultural society. The environmental factors examined were geology, physiography, soils, climate, hydrology, and vegetation. …
The Effects Of Drought On The Survival And Physiology Of Sporobolus Airoides (Torr.) Torr. Seedlings Of Varying Ages, John A. Mendenhall
The Effects Of Drought On The Survival And Physiology Of Sporobolus Airoides (Torr.) Torr. Seedlings Of Varying Ages, John A. Mendenhall
Biology ETDs
The effects of increasing water stress on seedlings of Sporobolus airoides (Torr.) Torr. were investigated in the laboratory under controlled growth conditions. Three groups of seedlings were germinated and grown in soil with soil moisture above field capacity for 15, 20 and 25 days. At this time watering ceased and at the end of drought periods of 5, 10, 15 and 20 days some of the seedlings were examined for total carbohydrate content, respiratory activity, and relative shoot water deficits. Other plants were rewatered after each drought period and 20 days later survival was determined visually. The dry weights of …
Ua77/1 Western Alumnus, Vol. 42, No. 3, Wku Alumni Association
Ua77/1 Western Alumnus, Vol. 42, No. 3, Wku Alumni Association
WKU Administration Documents
WKU alumni magazine. Features the following articles:
- Corts, Paul. Western's Honors Program Forges Ahead
- Gray, David. Students Still Work Their Way
- Mefford, David & Roy Reynolds. Reaching Out for the Good Student
- Lawrence, Fred. Nick Rose All American
- Yeager, Randolph. A Westerner Remembers Harry Truman
- Scarborough, Clarice. Western Goes to Mexico
- Dillard, Gary & Rudolph Prins. Western at Tech Aqua
- Lawrence, Fred. Student Teaching - a la Guatemala
- Corts, Paul. Theatre Study Goes British
- Thompson, Kelly. The Most Unforgettable Person I Have Ever Known . . . Henry Cherry
- Commonwealth in a Capsule - Kentucky Building
- Adams, Ronald. Teacher Evaluation …
Attitudes On Population Crisis At A Small Liberal-Arts College, John B. Jenkins, R. C. Mitchell
Attitudes On Population Crisis At A Small Liberal-Arts College, John B. Jenkins, R. C. Mitchell
Biology Faculty Works
No abstract provided.
The Nature Of Miniature Melanocytes In Murine Epidermis, John Thomas Earnhardt
The Nature Of Miniature Melanocytes In Murine Epidermis, John Thomas Earnhardt
Master's Theses
In the epidermis of PET/Wmr mice the population of melanocytes reaches a peak and begins to decline during the first postnatal week, and has disappeared within four weeks. During this period a small number of weakly DOPA reactive miniature melanocytes are seen dispersed among the generally large, highly DOPA reactive melanocytes typical of the animal. These miniature melanocytes appear early, are among the last to disappear, and their population remains relatively constant against the drastically changing population of typical melanocytes. In attempts to determine the nature of the miniature melanocytes, heterologous grafting was employed whereby the melanocytes were subjected to …
Effect Of Gibberellic Acid And Actinomycin D On The Formation And Distribution Of Rough Endoplasmic Reticulum In Barley Aleurone Cells, Eugene L. Vigil, Manfred Ruddat
Effect Of Gibberellic Acid And Actinomycin D On The Formation And Distribution Of Rough Endoplasmic Reticulum In Barley Aleurone Cells, Eugene L. Vigil, Manfred Ruddat
Biological Sciences Faculty Research and Publications
Analysis of structural changes in barley aleurone cells during germination or following incubation of isolated layers in gibberellic acid with or without actinomycin D revealed extensive development of rough endoplasmic reticulum. Following the assembly of stacked rough endoplasmic reticulum, vesiculation occurred mainly in basal regions of the cell, resulting in a polar distribution of rough endoplasmic reticulum vesicles. It is postulated that these vesicles are involved in protein secretion, because smooth vesicles, derived from the rough endoplasmic reticulum, apparently become appressed to the plasma membrane. The increased α-amylase in the ambient medium and in cell homogenates correlated directly with formation …
Ua66/6/ Alumni Newsletter, Wku Biology
Ua66/6/ Alumni Newsletter, Wku Biology
WKU Administration Documents
Initial letter to alumni soliciting information regarding their activities. Also includes some departmental history and lists of faculty and scholarship recipients.
Some Effects Of The Bite Of The Short-Tailed Shrew, Blarina Brevicauda, Howard F. Krosch
Some Effects Of The Bite Of The Short-Tailed Shrew, Blarina Brevicauda, Howard F. Krosch
Journal of the Minnesota Academy of Science
Folklore, especially in Europe, has long maintained that shrews are extremely poisonous. Zoologists have discounted this belief as superstition until recently, when it was learned that at least two species of shrews - the European water shrew, Neomys fodiens, and the American short-tailed shrew, Blarina brevicauda - produce a toxin in their sub-maxillary glands.
Fishes Collected In Morro Bay, California Between January, 1968 And December, 1970, Harry L. Fierstine, Kurt F. Kline, Gregory R. Garman
Fishes Collected In Morro Bay, California Between January, 1968 And December, 1970, Harry L. Fierstine, Kurt F. Kline, Gregory R. Garman
Biological Sciences
Sixty-six species of fish were collected in Morro Bay between January, 1968 and December, 1970. The bay was divided into five ecological zones. Zone I was characterized by sandy beaches with little algae and contained 10 species. Zone II contained 35 species and was characterized by a sandy-silt bottom with some Zostera and kelp beds scattered among commercial piers. Zone III contained 31 species and was characterized by more Zostera beds and fewer commercial developments than Zone II. Zone IV contained 30 species and was characterized by large expanses of shallow Zostera beds dissected by very narrow channels. Zone V …
Ribosomes Of Acid-Fast Bacilli - Immunogenicity, Serology, And In-Vitro Correlates Of Delayed-Hypersensitivity, Robert E. Baker, Walter E. Hill, C. L. Larson
Ribosomes Of Acid-Fast Bacilli - Immunogenicity, Serology, And In-Vitro Correlates Of Delayed-Hypersensitivity, Robert E. Baker, Walter E. Hill, C. L. Larson
Biological Sciences Faculty Publications
No abstract provided.
Resistance Of Mice To Infection With Friend Disease Virus After Subcutaneous Injection Of Friend Virus And Friend Spleen-Cells, C. L. Larson, R. N. Ushijima, S. K. Kasuga, Robert E. Baker, M. B. Baker
Resistance Of Mice To Infection With Friend Disease Virus After Subcutaneous Injection Of Friend Virus And Friend Spleen-Cells, C. L. Larson, R. N. Ushijima, S. K. Kasuga, Robert E. Baker, M. B. Baker
Biological Sciences Faculty Publications
No abstract provided.
Evidence For An Ambidirectional Magnesium-Activated, Sodium-Potassium Dependent Adenosine Triphosphatase, John Dale Hempel
Evidence For An Ambidirectional Magnesium-Activated, Sodium-Potassium Dependent Adenosine Triphosphatase, John Dale Hempel
Master's Theses
Controversy exists as to whether the Na-K ATPases of euryhaline fishes are the same enzyme.This study demonstrates that the phosphorylated enzyme from gills of Fundulus heteroclitus adapted to freshwater and salt water migrate to the same position in SDS polyacrylamide gels. Similar behavior of the enzyme from both sources in different ionic media is also shown. Additionally, the possible ability or the enzyme to couple an osmoregulatory influx to an excretory efflux in freshwater fish is demonstrated. The term "ambidirectional" is proposed for this enzyme, and its place in certain membrane models is discussed.
The Effect Of Aflatoxin B1 On Growth Rate And Iron Metabolism In Juvenile Mongolian Gerbils (Meriones Unguiculatus), William Stanley Hastings Jr.
The Effect Of Aflatoxin B1 On Growth Rate And Iron Metabolism In Juvenile Mongolian Gerbils (Meriones Unguiculatus), William Stanley Hastings Jr.
Theses and Dissertations
The metabolic secretions from Aspergillus flavus, aflatoxins. are often found as contaminants of agricultural products used for human and animal consumption. Aflatoxin B1 is the most toxic and carcinogenic of the aflatoxins. A reduction in weight gain has been observed when juvenile animals are fed aflatoxin B1 over an extended period of time. This reduction in weight gain may possibly result from an anemic condition induced by an alteration of iron absorption and/or distribution. The effect of chronic sublethal levels of this hepatocarcinogen on weight gain and the uptake and distribution of 59Fe++ were studied in this investigation.
An experimental …
The Effects Of Ultraviolet Irradiation On The Pigment Cells Of The Pet/Wmr Mouse Epidermis, Vaughan Henry Howard Jr.
The Effects Of Ultraviolet Irradiation On The Pigment Cells Of The Pet/Wmr Mouse Epidermis, Vaughan Henry Howard Jr.
Master's Theses
Epidermal melanocytes in mammals are known to occur in a variety of shapes, sizes, and colors. The basic melanocyte morphology is dependent upon genetics, but there are a number of environmental factors that can cause modification.
In the epidermis of PET/\vrnr mice, the population of rnelanocytes reaches a peak and begins to decline during the first post-natal week, and has disappeared within four weeks. Dispersed among the large, highly DOPA-reactive melanocytes are miniature melanocytes. These miniature melanocytes are weakly DOPA-reactive and appear early in the post-natal period. The miniature melanocyte population is relatively constant and these miniature cells are among …
Experimentally-Induced Muscle Atrophy In The Developing Chick Embryo: Glycogen Metabolism, Michael J. Harris
Experimentally-Induced Muscle Atrophy In The Developing Chick Embryo: Glycogen Metabolism, Michael J. Harris
Journal of the Minnesota Academy of Science
Glycogen content and the activities of phosphorylase (PHRL) and glycogen synthetase (GS) in the hind limb muscle of normal, unilaterally (right) - denervated and in nicotine sulfate (NS) - injected chick embryos were determined to assess the effect of the experimental treatments on glycogen metabolism. Glycogen content increased with increase in age in normal limbs, remained relatively low in denervated limbs, increased with age in left (unoperated) limbs of denervated embryo limbs at a rate lower than normal except between days 13 and 17 of incubation, when glycogen content tripled. The same parameter in NS-injected embryo limbs remained generally low …
Histology Of The Small Intestine Of The Mink, Mustela Vison, Don Hurdman Bark Iii
Histology Of The Small Intestine Of The Mink, Mustela Vison, Don Hurdman Bark Iii
All Master's Theses
This thesis was designed to provide a histological and histochemical survey of the small intestine of the mink, Mustela vison. These two objectives were achieved and it was found that the histology and enzyme activity in this animal is in most respects similar to other mammals. Exceptions to this are the absence of a cecum and an ileocecal valve and the absence of lactase activity in the small intestine.
A Limnological Study Of Shadow Lake, A Subalpine Lake At Mount Rainer National Park, Washington, Timothy J. Hall
A Limnological Study Of Shadow Lake, A Subalpine Lake At Mount Rainer National Park, Washington, Timothy J. Hall
All Master's Theses
This paper presents a general limnological survey of a subalpine lake ecosystem. Physical, chemical and biological parameters were considered. Chemical and physical factors were dominated by the influence of snow-ice cover and high amounts of solar radiation. Abiotic factors result in a small phytoplankton standing crop and limitation of activity by photosynthetic organisms to the short summer season. Zooplankton and benthic communities are simplified in species composition and population size in response to the small primary producer population.
Isolation And Characterization Of Two Bacteriophages Infecting The Myxobacterium Cytophaga Succinicans, Kenneth Wayne Lee
Isolation And Characterization Of Two Bacteriophages Infecting The Myxobacterium Cytophaga Succinicans, Kenneth Wayne Lee
All Master's Theses
Two bacteriophages which infect the myxobacterium Cytophaga succinicans, strains 14 and 16, were isolated from fish hatchery effluent. Each was submitted to a detailed study. These phages have a limited host range, even within the genus Cytophaga. The turbid plaques formed by these phages are similar in appearance to those produced by coliphage Lambda, and average 0.85 mm in diameter. Both phages have a latent period of 195 minutes and a rise period of an additional 165 minutes. Phage 0CS-16 has a burst size of 137 and phage 0CS-14 has a burst of 45. Sodium ion at a concentration of …
Karyology And Sex In Clematis Ligusticifolia Nutt. (Ranunculaceae), Darrel A. White
Karyology And Sex In Clematis Ligusticifolia Nutt. (Ranunculaceae), Darrel A. White
All Master's Theses
An investigation was conducted to determine the relationship between sex and karyology in Clematis ligusticifolia Nutt. (Ranunculaceae), a dioecious perennial.
Chromosome number and karyology of this species are discussed and a review of some of the major works of previous investigators of sex determinism in dioecious angiosperms is included.
A Taxonomic Study Of The Balsamorhiza Hookeri Nutt. Balsamorhiza Hirsuta Nutt. Complex, Mary Clay Muller
A Taxonomic Study Of The Balsamorhiza Hookeri Nutt. Balsamorhiza Hirsuta Nutt. Complex, Mary Clay Muller
All Master's Theses
In this study a multivariate statistical analysis utilizes the linear discriminant function that has been used to substantiate the shift of the variety lagocephala (Sharp) Cronq., from Balsamorhiza hirsuta, to B. hookeri (Cronquist, 1955). This method can be used to determine the placement of other questionable taxa.
In addition, this paper deals with the history, morphology and distribution of B. hirsuta, B. hookeri var. hookeri, and B. hookeri var. lagocephala.
Relationship Of Heart Weight To Altitude In The Oregon Junco, Donald Lee Gatlin
Relationship Of Heart Weight To Altitude In The Oregon Junco, Donald Lee Gatlin
All Master's Theses
This paper presents a statistical analysis of dry heat weights from Oregon Juncos obtained at various altitudes.