scholarly journals Identifying Pre-Dorset structural features on southern Baffin Island: Challenges and considerations for alternative sampling methods

2005 ◽  
Vol 27 (1-2) ◽  
pp. 67-90 ◽  
Author(s):  
S. Brooke Milne
Keyword(s):  
Sampling Methods ◽  
Structural Features ◽  
Baffin Island ◽  
Core Sampling ◽  
Combined Strategy ◽  
Debitage Analysis

Abstract This paper describes an isolated Pre-Dorset component found at the Tungatsivvik (KkDo-3) site on southern Baffin Island. Micro-debitage analysis and systematic core sampling are proposed as a combined strategy to facilitate future investigations of Pre-Dorset occupations in this region.

Experiments in Sanitizing Beef With Sodium Hypochlorite1,2

1977 ◽  
Vol 40 (4) ◽  
pp. 246-249 ◽  
Author(s):  
R. T. MARSHALL ◽  
M. E. ANDERSON ◽  
H. D. NAUMANN ◽  
W. C. STRINGER
Keyword(s):  
Sodium Hypochlorite ◽  
Sampling Methods ◽  
Microbial Populations ◽  
Microbial Counts ◽  
Core Sampling ◽  
Single Passage ◽  
Line Pressure

Beef plate meat was sprayed with sodium hypochlorite (pH 6.0) from two sources, commercial and electroytically generated. Variables studied in two experiments were rate of flow of sanitizer, line pressure, speed of movement of meat through the sprays, and method and time of sanitization. Hypochlorite sprays reduced microbial counts significantly more than did water applied under the same conditions, but type of hypochlorite was unimportant. Maximum reductions in counts made immediately after sanitization approximated 97 and 93% as measured by swab and core sampling methods, respectively. Sprays were most effective when delivered in a single passage over meat at a rate of 2 rather than 10 cm/sec or in about seven successive passages at 10 cm/sec. Samples collected by coring and swabbing estimated microbial populations different from each other when the samples were taken after sanitized meat had been stored at 3 C for 48 h. Based on our findings we recommend the coring method.

A practical modification of horizontal line sampling for snag and cavity tree inventory

2002 ◽  
Vol 32 (7) ◽  
pp. 1217-1224 ◽  
Author(s):  
M J Ducey ◽  
G J Jordan ◽  
J H Gove ◽  
H T Valentine
Keyword(s):  
Sampling Methods ◽  
Structural Features ◽  
Horizontal Line ◽  
Confidence Limits ◽  
Unbiased Estimators ◽  
Line Sampling ◽  
Tree Inventory ◽  
Special Cases ◽  
Cavity Tree ◽  
Better Than

Snags and cavity trees are important structural features in forests, but they are often sparsely distributed, making efficient inventories problematic. We present a straightforward modification of horizontal line sampling designed to facilitate inventory of these features while remaining compatible with commonly employed sampling methods for the living overstory. The method is simpler in its implementation than traditional horizontal line sampling. We develop unbiased estimators and present methods for dealing with special cases, including boundary overlap. A field test of the method shows it to have time efficiency comparable with or better than ordinary prism cruising, and it requires far fewer sample locations to achieve similar confidence limits. The method may also be useful for inventorying other rare or unusual trees.

Estimating the species number and cover of a mangrove-root community: a comparison of methods

1992 ◽  
Vol 43 (4) ◽  
pp. 707 ◽  
Author(s):  
H Diaz ◽  
JE Conde ◽  
B Orihuela
Keyword(s):  
Sample Size ◽  
Sampling Design ◽  
Sampling Methods ◽  
Computer Hardware ◽  
Species Number ◽  
Mangrove Root ◽  
Mangrove Roots ◽  
Basic Features ◽  
Combined Strategy ◽  
Video Material

Methods and designs have been validated for sampling coral reefs and reef-associated communities, but the accuracy and equivalence of results obtained from studies of mangrove-root communities can not be assured. Thus, it is convenient to establish the accuracy and reliability of sampling methods on a practical basis. Line interception, point interception, and quadrat sampling were used to estimate several basic features of the community associated with mangrove roots. Species-number estimates, cover estimates, sampling efforts, and some statistical properties of the three methods were compared. A sampling design should be chosen if it yields estimates with the greatest accuracy at the lowest cost. Results showed that sampling of mangrove roots could start by using 4 × 4-cm quadrats with a mean sample size of 50 for detecting the number of species, and for establishing species cover it appears that the point-interception method with a sample size of 50 would be appropriate. The effort involved in such a sequence would be approximately 10 h for 20 roots. This combined strategy is clearly laborious and time-consuming in comparison with the use of just a 200-point interception, which would require only 3.25 h for the same number of roots. Although it would cost more than the above methods, a fast and accurate technique based upon existing computer hardware to estimate cover from photographic or video material would result in a census of the whole community. This might prove to be a reliable way to approach the problem.

Electron microscopy and diffraction studies of polyimides

1983 ◽  
Vol 41 ◽  
pp. 28-29
Author(s):  
O.C. de Hodgins ◽  
K. R. Lawless ◽  
R. Anderson
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Structural Features ◽  
Inert Atmosphere ◽  
Polyimide Films ◽  
Resolution Electron ◽  
The Matrix ◽  
High Resolution Electron Microscope ◽  
Diffraction Patterns ◽  
Polymeric Samples

Commercial polyimide films have shown to be homogeneous on a scale of 5 to 200 nm. The observation of Skybond (SKB) 705 and PI5878 was carried out by using a Philips 400, 120 KeV STEM. The objective was to elucidate the structural features of the polymeric samples. The specimens were spun and cured at stepped temperatures in an inert atmosphere and cooled slowly for eight hours. TEM micrographs showed heterogeneities (or nodular structures) generally on a scale of 100 nm for PI5878 and approximately 40 nm for SKB 705, present in large volume fractions of both specimens. See Figures 1 and 2. It is possible that the nodulus observed may be associated with surface effects and the structure of the polymers be regarded as random amorphous arrays. Diffraction patterns of the matrix and the nodular areas showed different amorphous ring patterns in both materials. The specimens were viewed in both bright and dark fields using a high resolution electron microscope which provided magnifications of 100,000X or more on the photographic plates if desired.

Skeletal elements of crinoid echinoderms: High-resolution structural and microanalytical results

1983 ◽  
Vol 41 ◽  
pp. 194-195
Author(s):  
D. F. Blake ◽  
L. F. Allard ◽  
D. R. Peacor
Keyword(s):  
High Resolution ◽  
Marine Invertebrates ◽  
Sea Urchins ◽  
Structural Features ◽  
Sea Stars ◽  
High Resolution Tem ◽  
Relationship Of ◽  
The Relationship ◽  
Insight Into

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.

Study of the Molecular Architecture of Keratin Filaments by Electron Microscopy

1982 ◽  
Vol 40 ◽  
pp. 118-119
Author(s):  
U. Aebi ◽  
P. Rew ◽  
T.-T. Sun
Keyword(s):  
Electron Microscopy ◽  
Structural Organization ◽  
Cell Types ◽  
Structural Features ◽  
Molecular Architecture ◽  
The Past ◽  
Keratin Filaments ◽  
Different Types ◽  
10 Nm Filaments ◽  
Different Cell Types

Various types of intermediate-sized (10-nm) filaments have been found and described in many different cell types during the past few years. Despite the differences in the chemical composition among the different types of filaments, they all yield common structural features: they are usually up to several microns long and have a diameter of 7 to 10 nm; there is evidence that they are made of several 2 to 3.5 nm wide protofilaments which are helically wound around each other; the secondary structure of the polypeptides constituting the filaments is rich in ∞-helix. However a detailed description of their structural organization is lacking to date.

Measurement and Reduction of Radiation Damage in Frozen Hydrated Crystalline Specimens

1978 ◽  
Vol 36 (3) ◽  
pp. 70-77 ◽  
Author(s):  
R.M. Glaeser ◽  
S.B. Hayward
Keyword(s):  
Diffraction Pattern ◽  
Structural Information ◽  
Structural Disorder ◽  
Structural Features ◽  
Biological Macromolecules ◽  
Diffraction Intensity ◽  
Object Structure ◽  
Specimen Material ◽  
Unit Cells ◽  
Identical Unit

Highly ordered or crystalline biological macromolecules become severely damaged and structurally disordered after a brief electron exposure. Evidence that damage and structural disorder are occurring is clearly given by the fading and eventual disappearance of the specimen's electron diffraction pattern. The fading and disappearance of sharp diffraction spots implies a corresponding disappearance of periodic structural features in the specimen. By the same token, there is a oneto- one correspondence between the disappearance of the crystalline diffraction pattern and the disappearance of reproducible structural information that can be observed in the images of identical unit cells of the object structure. The electron exposures that result in a significant decrease in the diffraction intensity will depend somewhat upon the resolution (Bragg spacing) involved, and can vary considerably with the chemical makeup and composition of the specimen material.

Some Structural Features of Metaphase Chromosomes of Mice and Men

1967 ◽  
Vol 25 ◽  
pp. 190-191
Author(s):  
Godfrey C. Hoskins ◽  
Betty B. Hoskins
Keyword(s):  
Electron Microscopy ◽  
Electron Micrographs ◽  
Structural Features ◽  
Metaphase Chromosomes ◽  
The Future ◽  
Of Mice And Men ◽  
Mouse Cells ◽  
Human And Mouse

Metaphase chromosomes from human and mouse cells in vitro are isolated by micrurgy, fixed, and placed on grids for electron microscopy. Interpretations of electron micrographs by current methods indicate the following structural features.Chromosomal spindle fibrils about 200Å thick form fascicles about 600Å thick, wrapped by dense spiraling fibrils (DSF) less than 100Å thick as they near the kinomere. Such a fascicle joins the future daughter kinomere of each metaphase chromatid with those of adjacent non-homologous chromatids to either side. Thus, four fascicles (SF, 1-4) attach to each metaphase kinomere (K). It is thought that fascicles extend from the kinomere poleward, fray out to let chromosomal fibrils act as traction fibrils against polar fibrils, then regroup to join the adjacent kinomere.

Observations on the Structure of Ta2O5

1972 ◽  
Vol 30 ◽  
pp. 540-541
Author(s):  
P. S. Kotval ◽  
C. J. Dewit
Keyword(s):  
Electron Microscope ◽  
Structural Features ◽  
Amorphous Structure ◽  
Polished Surface ◽  
Distilled Water ◽  
Anodic Films ◽  
Amorphous Films ◽  
Beam Heating ◽  
Diffraction Patterns ◽  
Hexagonal Arrays

The structure of Ta2O5 has been described in the literature in several different crystallographic forms with varying unit cell lattice parameters. Earlier studies on films of Ta2O5 produced by anodization of tantalum have revealed structural features which are not consistent with the parameters of “bulk” Ta2O5 crystalsFilms of Ta2O5 were prepared by anodizing a well-polished surface of pure tantalum sheet. The anodic films were floated off in distilled water, collected on grids, dried and directly examined in the electron microscope. In all cases the films were found to exhibit diffraction patterns representative of an amorphous structure. Using beam heating in the electron microscope, recrystallization of the amorphous films can be accomplished as shown in Fig. 1. As suggested by earlier work, the recrystallized regions exhibit diffraction patterns which consist of hexagonal arrays of main spots together with subsidiary rows of super lattice spots which develop as recrystallization progresses (Figs. 2a and b).

Methods for making stereoslides and -prints, with freeze-etched olfactory epithelium as example

1984 ◽  
Vol 42 ◽  
pp. 704-705
Author(s):  
Bert Ph. M. Menco ◽  
Ido F. Menco ◽  
Frans L.T. Verdonk
Keyword(s):  
Electron Microscope ◽  
Olfactory Epithelium ◽  
Three Dimensional ◽  
Supporting Cell ◽  
Structural Features ◽  
Extensive Study ◽  
Sprague Dawley ◽  
Freezing Method ◽  
Respiratory Epithelia ◽  
Three Dimensional Presentation

Previously we presented an extensive study of the distributions of intramembranous particles of structures in apical surfaces of nasal olfactory and respiratory epithelia of the Sprague-Dawley rat. For the same structures these distributions were compared in samples which were i) chemically fixed and cryo-protected with glycerol before cryo-fixation, after excision, and ii)ultra-rapidly frozen by means of the slam-freezing method. Since a three-dimensional presentation markedly improves visualization of structural features micrographs were presented as stereopairs. Two exposures were made by tiling the sample stage of the electron microscope 6° in either direction with an eucentric goniometer. The negatives (Agfa Pan 25 Professional) were reversed with Kodak Technical Pan Film 2415 developed in D76 1:1. The prints were made from these reversed negatives. As an example tight-junctional features of an olfactory supporting cell in a region where this cell conjoined with two other cells are presented (Fig. 1).

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