Isochronous Interpretation of Some C14 Datesa Technique for Temporal and Regional Studies

Abstract

Isochronous maps contoured to values of absolute dates for two Paleo-Indian complexes provide the basis for extending some interpretations of culture which are derived from temporal data. Place and time of origin can be determined, if not with exactness, at least with a greater degree of accuracy through graphically interpreted cultural associated dates. Mere concentrations of sites and oldest dates are not always sufficient criteria for determining the probable center of development of cultures. Direction, distance and rate of diffusion or migration are read directly from the graphic presentation of the data. From a careful extrapolation of contoured values the probable contemporaneity of cultures such as Folsom and Clovis is demonstrable. Finally, a considerable degree of confidence can be placed in information derived by cautious extrapolation and interpolation of contoured values of isochronous maps.     

the Denver Elephant Project: a Report on Experimentation with Thrusting Spears

Abstract

One aspect of the Denver Elephant Project, the experimental use of thrusting spears, is presented. A recentlydeceased elephant was made available for archaeological experimentation, and as a part of this work the author manufactured and, with the aid of others, employed a series of thrusting spears tipped with Clovis fluted point replicas. It was found that the use of composite thrusting spears permitted penetration of the elephant carcass, but also revealed problems in spear design. The types of projectile point breakage which occurred were found to compare favorably with archaeological specimens. Other implications of the work for the understanding of Clovis elephant procurement strategy and weaponry are presented, and suggestions are made for future experiments.     

The Pelland and Moe Site Blades: Paleo-Indian Culture History in the Upper Midwest

Abstract

Analysis of artifacts recovered from the Moe site located in northwestern North Dakota reveals the presence of 15 blades and three blade-like flakes, the majority of which are made of Knife River Flint and have been modified by retouch flaking. A comparison of the Moe specimens to those from the Pelland site in northern Minnesota, the only other site from the study area which contains blades of Paleo-Indian age, indicates that the Moe specimens are smaller in all dimensions. The Pelland specimens are made of Knife River Flint and have been modified by retouch flaking. Examination of the literature on Paleo-Indian sites from the Plains region indicates that blade production is more common in Plano cultures particularly Agate Basin and Plainview-Goshen than in earlier Clovis or Folsom cultures or later Cody cultures. It is suggested that the Pelland and Moe site blades are Plano in age and most likely Agate Basin or Plainview-Goshen in cultural affiliation. A model provided by Leo Pettipas (1976) is used to suggest an eastward movement of Plains Plano cultures using Knife River Flint across southern Manitoba, eastern North Dakota, and into western and northern Minnesota following the recession of Glacial Lake Agassiz.     

Folsom Points from Southwest Texas

Abstract

A munber of Folsom points from southwestern Texas are described.     

Rummells-Maske: A Clovis Find-Spot in Iowa

Abstract

The first controlled excavation of a Clovis site in Iowa revealed a concentration of complete and fragmentary Clovis Fluted projectile points. The site, in eastern Iowa, is interpreted as a projectile point cache destroyed by agricultural implements. Measurements and photographs are provided to facilitate the comparison of the collection with assemblages from other states.     

Agate Basin Technology: An Insight

Abstract

An example of a serrate biface from the Agate Basin level of the Hell Gap site is examined from a technological and use-wear analytic perspective. Two possible explanations for marginal serration, to produce a “sawlike edge” or for platform isolation, are evaluated. Results of this evaluation suggest that platform isolation is a more plausible explanation in this case. This explanation may imply technological/cultural continuity between Folsom and Agate Basin biface manufacturing populations.     

Hell Gap: Paleo-Indian Occupation on the High Plains

Abstract

A resume of archaeological investigations in the Hell Gap Valley of southeastern Wyoming is presented. This research produced a detailed sequence of Plains PaleoIndian occupation of this section of the High Plains. from about 9000 to 5500 B.C. Identifiable complexes recognized include Goshen, Midland, Folsom, Agate Basin, Hell Gap, Alberta, Cody, and Frederick. Materials recovered represent camping activities rather than the better known game kills, and add dimension to our knowledge of Plains Paleo-Indian cultures.     

Breakage Patterns of Central Illinois Woodland Projectile Points

Abstract

In most projectile point assemblages, it is common to find a large proportion of broken specimens. Assuming most broken specimens were broken prior to deposition in the archaeological record, three possible factors correlating with breaks are examined: (1) blade proportions, (2) major functional category, (3) haft morphology. Hypotheses for the role of each factor are framed and tested on a group of specimens from central Illinois. Use category appears to be the major factor in blade breakage, although total extent of breakage is also related to haft morphology.     

Complete nationwide survey on umbilical cord blood freezing bag breakage in Japan

Background aimsAlthough umbilical cord blood (UCB) has now become a common stem cell source, UCB bag breakage is a known risk in UCB transplantation (UCBT). This survey provides the first comprehensive data on the frequency and causes of UCB bag breakage in Japan.MethodsData regarding UCB bag breakage from all causes, identified between April 1, 2010, and September 3, 2013, were collected from all transplant centers registered for UCBT (209 hospitals) and all public cord blood banks (CBBs) (8 CBBs) in Japan.ResultsSeventeen incidents of UCB bag breakage at CBBs were confirmed, none of which resulted in bags being shipped to transplant centers. From among 3836 UCBT, 16 incidents (0.4%) of UCB bag breakage were confirmed at transplant centers. Although all these bags were used for transplantation, no direct health hazard was reported. The major cause of UCB bag breakage confirmed at transplant centers was considered to be external force (75%). In addition, 11 incidents of unexplained UCB bag breakage at sealing between compartments were reported.ConclusionsUCB bag breakage was confirmed at both CBBs and transplant centers. UCB bags should be handled with particular care and attention.     

DNA Apurinic Sites: Synthesis of a Model Compound and Study of its Reactivity with 3-Aminocarbazole

Abstract

The mechanism of breakage of apurinic DNA with 3-aminocarbazole was determinated on a short oligonucleotide model. The results founded contrast with those reported in the literature.¹     

The Midland Complex: Is It Valid?

The Midland point has the same general shape, size, and typological manufacture as the unfluted Folsom point and may represent a minor style variation within a single cultural complex. The Paleo-Indians who made both Midland (unfluted Folsom) and classical Folsom points occupy nearly identical time spans and have nearly identical associated tools. While individual sites have been found with all Midland and all Classic Folsom projectiles, many Folsom sites have both fluted and unfluted points found in the same chronological time horizon. The question is: with the available evidence, can we place them into separate complexes?     

Reconstruction with Modular Hemipelvic Endoprosthesis after Pelvic Tumor Resection: A Report of 50 Consecutive Cases

PurposeTo evaluate the effectiveness of reconstruction with a modular hemipelvic endoprosthesis after pelvic tumor resection.MethodsWe retrospectively studied 50 consecutive patients diagnosed with pelvic tumor from 2003 to 2013. All patients received limb-salvage surgery and reconstruction with modular hemipelvic endoprosthesis.ResultsPatients were followed for an average of 54 months. At the most recent follow-up, 32 patients were alive with an estimated three-year and five-year survival rate of 66.3% and 57.5% according to the Kaplan-Meier survival analysis. Eighteen patients died from the tumor, with a mean survival of 28 months, and 9 patients experienced local recurrence at an average of 19.6 months after surgery. Patients with marginal or intracapsular surgical margins had a significantly higher recurrence rate than those with wide margins (p=0.02). Metastasis occurred in 12 cases at an average of 16 months after surgery. The perioperative complication rate was 48.0%, and the most common complications were wound healing disturbance (28.0%) and deep infection (14.0%). The endoprosthetic complication rate was 16.0%, and breakage of the pubic connection plate was the most common complication. The mean Musculoskeletal Tumor Society score was 61.4%.ConclusionReconstruction with a modular hemipelvic endoprosthesis after pelvic tumor resection can improve function, with an acceptable complication rate.     

Evaluation of oxidative DNA damage in pigeon erythrocytes using DNA breakage detection-fluorescence in situ hybridization (DBD-FISH)

ABSTRACT

DNA breakage detection-fluorescence in situ hybridization (DBD-FISH) enables detection and quantification of DNA breakage in the entire genome or within specific DNA sequences in single cells. We used this method to visualize and evaluate DNA damage in pigeon erythrocytes that were induced by elevated temperature and hydrogen peroxide. We also examined morphological changes in the cell nuclei. DBD-FISH demonstrated a significant increase of DNA damage in a temperature dependent manner, which resulted in nuclear abnormalities associated with apoptotic cells. These cells gave strong nuclear fluorescent signals that indicated cell death.     

Fluoroquinolones stimulate the DNA cleavage activity of topoisomerase IV by promoting the binding of Mg2 + to the second metal binding site

BackgroundFluoroquinolones target bacterial type IIA topoisomerases, DNA gyrase and topoisomerase IV (Topo IV). Fluoroquinolones trap a topoisomerase–DNA covalent complex as a topoisomerase–fluoroquinolone–DNA ternary complex and ternary complex formation is critical for their cytotoxicity. A divalent metal ion is required for type IIA topoisomerase-catalyzed strand breakage and religation reactions. Recent studies have suggested that type IIA topoisomerases use two metal ions, one structural and one catalytic, to carry out the strand breakage reaction.MethodsWe conducted a series of DNA cleavage assays to examine the effects of fluoroquinolones and quinazolinediones on Mg^2 +-, Mn^2 +-, or Ca^2 +-supported DNA cleavage activity of Escherichia coli Topo IV.ResultsIn the absence of any drug, 20–30 mM Mg^2 + was required for the maximum levels of the DNA cleavage activity of Topo IV, whereas approximately 1 mM of either Mn^2 + or Ca^2 + was sufficient to support the maximum levels of the DNA cleavage activity of Topo IV. Fluoroquinolones promoted the Topo IV-catalyzed strand breakage reaction at low Mg^2 + concentrations where Topo IV alone could not efficiently cleave DNA.Conclusions and general significanceAt low Mg^2 + concentrations, fluoroquinolones may stimulate the Topo IV-catalyzed strand breakage reaction by promoting Mg^2 + binding to metal binding site B through the structural distortion in DNA. As Mg^2 + concentration increases, fluoroquinolones may inhibit the religation reaction by either stabilizing Mg^2 + at site B or inhibition the binding of Mg^2 + to site A. This study provides a molecular basis of how fluoroquinolones stimulate the Topo IV-catalyzed strand breakage reaction by modulating Mg^2 + binding.     

A simplified chromatin dispersion (nuclear halo) assay for detecting DNA breakage induced by ionizing radiation and chemical agents

Abstract

Methods for visualizing DNA damage at the microscopic level are based on treatment of cell nuclei with saline or alkaline solutions. These procedures for achieving chromatin dispersion produce halos that surround the nuclear remnants. We improved the fast halo assay for visualizing DNA breakage in cultured cells to create a simplified method for detection and quantitative evaluation of DNA breakage. Nucleated erythrocytes from chicken blood were selected as a model test system to analyze the production of nuclear halos after treatment with X-rays or H₂O₂. After staining with ethidium bromide or Wright's methylene blue-eosin solution, nuclear halos were easily observed by fluorescence or bright-field microscopy, respectively, which permits rapid visualization of DNA breakage in damaged cells. By using image processing and analysis with the public domain ImageJ software, X-ray dose and H₂O₂ concentration could be correlated well with the size of nuclear halos and the halo:nucleus ratio. Our results indicate that this simplified nuclear halo assay can be used as a rapid, reliable and inexpensive procedure to detect and quantify DNA breakage induced by ionizing radiation and chemical agents. A mechanistic model to explain the differences between the formation of saline or alkaline halos also is suggested.     

The late Pleistocene cultures of South America

Important to an understanding of the first peopling of any continent is an understanding of human dispersion and adaptation and their archeological signatures. Until recently, the earliest archeological record of South America was viewed uncritically as a uniform and unilinear development involving the intrusion of North American people who brought a founding cultural heritage, the fluted Clovis stone tool technology, and a big-game hunting tradition to the southern hemisphere between 11,000 and 10,000 years ago.^1–3 Biases in the history of research and the agendas pursued in the archeology of the first Americans have played a major part in forming this perspective.^4–6 Despite enthusiastic acceptance of the Clovis model by a vast majority of archeologists, several South American specialists have rejected it.^6–11 They contend that the presence of archeological sites in Tierra del Fuego and other regions by at least 11,000 to 10,500 years ago was simply insufficient time for even the fastest migration of North Americans to reach within only a few hundred years. Despite this concern, and despite the discovery of several pre-Clovis sites in South America,^6,10–12 some specialists^2,3 keep the Clovis model alive. Proponents of the model claim that the pre-Clovis sites are unreliable due to questionable radiocarbon dates, artifacts, and stratigraphy. Solid evidence at the Monte Verde site in Chile^14–16 and other localities^6,8,10–12 now indicates that South America was discovered by humans at least 12,500 years ago. How much earlier than 12,500 years ago is still a matter of conjecture.^6,10,12,15 Some proponents prefer a long chronology of 20,000 to 45,000 years ago,⁸ while others advocate a short chronology of 15,000 to 20,000 years ago^10–12 or only 11,000 years ago.^1–3. © 1999 Wiley-Liss, Inc.     

Investigation of a Proposed Mechanism for Genotoxic Effects Induced by 2-Hydroxyalkylating Agents. Kinetics of Intramolecular Transesterification in Dithymidine 2-Hydroxyethyl-and 2-Hydroxypropyl Phosphate

Abstract

Alkylation of DNA gives rise to adducts, not only at the bases, but also at the phosphate groups giving phosphotriesters^1–3. 2-Hydroxy-alkylation of phosphodiester functions in DNA causes considerable strand breakage already in neutral solution⁴. This effect has been suggested to be involved in the higher genotoxicity of 2-hydroxyalkylating agents as compared to, for instance, the corresponding methoxy compounds⁵.     

A mechanistic damage model for ligaments

PurposeThe accuracy of biomechanical models is predicated on the realism by which they represent their biomechanical tissues. Unfortunately, most models use phenomenological ligament models that neglect the behaviour in the failure region. Therefore, the purpose of this investigation was to test whether a mechanistic model of ligamentous tissue portrays behaviour representative of actual ligament failure tests.ModelThe model tracks the time-evolution of a population of collagen fibres in a theoretical ligament. Each collagen fibre is treated as an independent linear cables with constant stiffness. Model equations were derived by assuming these fibres act as a continuum and applying a conservation law akin to Huxley’s muscle model. A breaking function models the rate of collagen fibre breakage at a given displacement, and was chosen to be a linear function for this preliminary analysis.MethodsThe model was fitted to experimental average curves for the cervical anterior longitudinal ligament. In addition, the model was cyclically loaded to test whether the tissue model behaves similarly.ResultsThe model agreed very well with experiment with an RMS error of 14.23 N and an R² of 0.995. Cyclic loading exhibited a reduction in force similar to experimental data.Discussion and conclusionThe proposed model showcases behaviour reminiscent of actual ligaments being strained to failure and undergoing cyclic load. Future work could incorporate viscous effects, or validate the model further by testing it in various loading conditions. Characterizing the breaking function more accurately would also lead to better results.     

Study on canopy disturbance regime and mechanism of tree species diversity maintenance in the lower subtropical evergreen broad-leaved forest,South China

ABSTRACT

The canopy disturbance, the gap environment, gap regeneration and maintenance of tree species diversity in the lower subtropical evergreen broad-leaved forest (LSEBF) of South China were studied in this paper. The most common manner of gap formation in the forest was by stem breakage. Most gaps were formed by two gap makers. The sizes of most expanded gaps (EG) and canopy gaps (CG) were in the range of 100 – 300 m² and 50 – 100 m², respectively. The ecological factors in gaps were analysed on the basis of contrasting measurement of the microclimatic regimes in gaps of different sizes and in non-gap stands. Tree species in the LSEBF were classified into 5 ecological species groups on the bases of their changes in order of importance values in gaps and in non-gap stands. Most of the species reached their peak of regeneration density around the gap sizes of 100 m² and 500 m². The curves of regeneration density vs. gap age for major species revealed two types. Regeneration densities of most species, and species diversity indices in gaps were greater than those in non-gap stands.