The Early Contact Period in the Black Prairie of Northeast Mississippi

2020 ◽  
pp. 35-56
Author(s):  
EDMOND A. BOUDREAUX ◽  
CHARLES R. COBB ◽  
EMILY CLARK ◽  
CHESTER B. DEPRATTER ◽  
JAMES B. LEGG ◽  
...  
Keyword(s):  
Contact Period ◽  
Northeast Mississippi

Individual mechanisms underlying peripheral nerve damage when exposed to metallic mercury

2020 ◽  
Vol 60 (12) ◽  
pp. 918-924
Author(s):  
Dina V. Rusanova ◽  
Oleg L. Lakhman ◽  
Galina M. Bodienkova ◽  
Irina V. Kudaeva ◽  
Natalya G. Kuptsova
Keyword(s):  
Peripheral Nerve ◽  
Peripheral Nerves ◽  
Blood Circulation ◽  
The State ◽  
Contact Period ◽  
Peripheral Nerve Damage ◽  
Demyelinating Disorders ◽  
Peripheral Blood Circulation ◽  
Antibodies To Dna

Introduction. There is a lack of knowledge of the pathophysiological mechanisms that form peripheral nerve disorders in mercury lesions of professional origin. The study aims to reveal the mechanisms underlying peripheral nerve damage in the long-term post-contact period of chronic mercury intoxication (CMI). Materials and methods. Fifty-one people had the diagnosis of a long-term period of CMI. The post-contact period was 8.5±2.6 years. The authors compared the results with a control group of 26 healthy men who had no contact with toxic substances. Stimulating electroneuromyography was performed. We studied the body systems that could contribute to the formation of disorders in the peripheral nerves. Changes in peripheral hemodynamics were studied using reovasography. The content of autoantibodies, neuron-specific enolase, serotonin, histamine, catecholamines (epinephrine, dopamine), metanephrine, and neurotrophin-3 was reviewed. The content of ceruloplasmin, secondary products of lipid peroxidation processes, reduced glutathione, the activity of superoxide dismutase and the content of nitric oxide levels were determined. Results. The study established pathogenetic structural links of peripheral nerve disorders. The autoimmune process's role was to increase the range of antibodies to the MAG protein and increase the level of antibodies to DNA. Violations of elastic-tonic properties of peripheral vessels could be associated with the functional state of motor axons. The increased content of neurotransmitters is related to the state of peripheral blood circulation; the most pronounced changes were on the legs, which could contribute to the occurrence and maintenance of vasoconstriction. The role of oxidative stress in the formation of demyelinating disorders in patients' peripheral nerves in the long-term period of CRI is possible. Conclusion. Neuroimmunological processes has an essential role in the development of peripheral nerve demyelination was shown, which consists in an increase in the content of antibodies to the MAG protein expressed on Schwann cells of peripheral nerves and in an increase in the level of antibodies to DNA involved in the formation of demyelinating changes when exposed to metallic mercury. The revealed pathological changes in the state of the peripheral blood circulation, characterized by a violation of the vessels' elastic-tonic properties, leading to demyelination of motor axons in patients in the long-term period of CMI. The increased content of neurotransmitters in the examined is of great importance in the state of peripheral circulation. Pronounced changes in blood circulation are established on the lower extremities, which may be associated with the predominance of α-adrenergic receptors in the arterial bed and may contribute to the occurrence and maintenance of vasoconstriction in the legs. The relationship between changes in indicators of oxidative stress, consisting of a decrease in the value of superoxide dismutase and reduced glutathione, and the formation of demyelinating disorders of peripheral nerves in patients in the long-term period of CMI has been proved.

Neurophysiological and morphological effects in the post-exposure vibration period during experimental modeling

2019 ◽  
pp. 284-290
Author(s):  
Natalya L. Yakimova ◽  
Vladimir A. Pankov ◽  
Aleksandr V. Lizarev ◽  
Viktor S. Rukavishnikov ◽  
Marina V. Kuleshova ◽  
...  
Keyword(s):  
Nervous System ◽  
Evoked Potentials ◽  
Experimental Model ◽  
Visual Evoked Potentials ◽  
The Body ◽  
Behavioral Activity ◽  
Contact Period ◽  
Vibration Exposure ◽  
Visual Evoked

Introduction. Vibration disease continues to occupy one of the leading places in the structure of professional pathology. In workers after the termination of contact with vibration generalization and progression of violations in an organism is noted. The pathogenetic mechanisms of the progredient course of disturbances in the nervous system in the post-contact period of vibration exposure remain insufficiently studied.The aim of the study was to test an experimental model of vibration exposure to assess the neurophysiological and morphological effects of vibration in rats in the dynamics of the post-contact period.Materials and methods. The work was performed on 168 white male outbred rats aged 3 months weighing 180–260 g. The vibration effect was carried out on a 40 Hz vibrating table for 60 days 5 times a week for 4 hours a day. Examination of animals was performed after the end of the physical factor, on the 30th, 60th and 120th day of the post-contact period. To assess the long-term neurophysiological and morphofunctional effects of vibration in rats, we used indicators of behavioral reactions, bioelectric activity of the somatosensory zone of the cerebral cortex, somatosensory and visual evoked potentials, parameters of muscle response, morphological parameters of nervous tissue.Results. In the dynamics of the post-contact period observed the preservation of violations of tentatively research, motor and emotional components of behavior. In the Central nervous system instability of activity of rhythms of an electroencephalogram, decrease in amplitude of visual evoked potentials, lengthening of latency of somatosensory evoked potentials, decrease in total number of normal neurons and astroglia is established. In the peripheral nervous system remained changes in indicators: increasing duration and latency, reducing the amplitude of the neuromuscular response.Conclusions: The experimental model allows us to study the long-term neurophysiological and morphological effects of vibration on the body. The formation and preservation of changes in behavioral activity, neurophysiological and morphological effects of vibration from the 30th to the 120th day of the post-contact period were confirmed.

scholarly journals History Disappearing: The Rapid Loss of Australian Contact Period Rock Art

2021 ◽  
Vol 46 (2) ◽  
pp. 119-131
Author(s):  
Paul S. C. Taçon ◽  
Sally K. May ◽  
Daryl Wesley ◽  
Andrea Jalandoni ◽  
Roxanne Tsang ◽  
...  
Keyword(s):  
Rock Art ◽  
Contact Period ◽  
Rapid Loss

scholarly journals An Analytical Solution for Non-Linear Viscoelastic Impact

Mathematics ◽  
2021 ◽  
Vol 9 (16) ◽  
pp. 1849
Author(s):  
Stelian Alaci ◽  
Constantin Filote ◽  
Florina-Carmen Ciornei ◽  
Oana Vasilica Grosu ◽  
Maria Simona Raboaca
Keyword(s):  
Analytical Solution ◽  
Hysteresis Loop ◽  
Viscoelastic Model ◽  
First Integral ◽  
Coefficient Of Restitution ◽  
Contact Period ◽  
Maximum Deformation ◽  
Impact Parameters ◽  
Simplified Algorithm ◽  
The Moment

The paper presents an analytical solution for the centric viscoelastic impact of two smooth balls. The contact period has two phases, compression and restitution, delimited by the moment corresponding to maximum deformation. The motion of the system is described by a nonlinear Hunt–Crossley equation that, when compared to the linear model, presents the advantage of a hysteresis loop closing in origin. There is only a single available equation obtained from the theorem of momentum. In order to solve the problem, in the literature, there are accepted different supplementary hypotheses based on energy considerations. In the present paper, the differential equation is written under a convenient form; it is shown that it can be integrated and a first integral is found—this being the main asset of the work. Then, all impact parameters can be calculated. The effect of coefficient of restitution upon all collision characteristics is emphasized, presenting importance for the compliant materials, in the domain of small coefficients of restitution. The results (variations of approach, velocity, force vs. time and hysteresis loop) are compared to two models due to Lankarani and Flores. For quasi-elastic collisions, the results are practically the same for the three models. For smaller values of the coefficient of restitution, the results of the present paper are in good agreement only to the Flores model. The simplified algorithm for the calculus of viscoelastic impact parameters is also presented. This algorithm avoids the large calculus volume required by solving the transcendental equations and definite integrals present in the mathematical model. The method proposed, based on the viscoelastic model given by Hunt and Crossley, can be extended to the elasto–visco–plastic nonlinear impact model.

The effect of research activities and winter precipitation on voiding behaviour of Agassiz’s desert tortoises (Gopherus agassizii)

2014 ◽  
Vol 41 (8) ◽  
pp. 641 ◽  
Author(s):  
Mickey Agha ◽  
Mason O. Murphy ◽  
Jeffrey E. Lovich ◽  
Joshua R. Ennen ◽  
Christian R. Oldham ◽  
...  
Keyword(s):  
Stress Responses ◽  
Handling Time ◽  
Winter Precipitation ◽  
Contact Period ◽  
Gopherus Agassizii ◽  
Desert Tortoise ◽  
Defensive Strategy ◽  
Survivorship Analysis ◽  
Research Activities

Context There is little information available on how research activities might cause stress responses in wildlife, especially responses of threatened species such as the desert tortoise (Gopherus agassizii). Aims The present study aims to detect behavioural effects of researcher handling and winter precipitation on a natural population of desert tortoises in the desert of Southwestern United States, over the period 1997 to 2014, through extensive assessments of capture events during multiple research studies, and capture–mark–recapture survivorship analysis. Methods Juvenile and adult desert tortoises were repeatedly handled with consistent methodology across 18 years during 10 study seasons. Using a generalised linear mixed-effects model, we assessed the effects of both research manipulation and abiotic conditions on probability of voiding. Additionally, we used a Cormack–Jolly–Seber model to assess the effects of winter precipitation and voiding on long-term apparent survivorship. Key results Of 1008 total capture events, voiding was recorded on 83 (8.2%) occasions in 42 different individuals. Our top models indicated that increases in handling time led to significantly higher probabilities of voiding for juveniles, females and males. Similarly, increases in precipitation resulted in significantly higher probabilities of voiding for juveniles and females, but not for males. Tortoise capture frequency was negatively correlated with voiding occurrence. Cormack–Jolly–Seber models demonstrated a weak effect of winter precipitation on survivorship, but a negligible effect for both voiding behaviour and sex. Conclusions Handling-induced voiding by desert tortoises may occur during common research activities and years of above average winter precipitation. Increased likelihood of voiding in individuals with relatively low numbers of recaptures suggested that tortoises may have perceived researchers initially as predators, and therefore voided as a defensive strategy. Voiding does not appear to impact long-term survivorship in desert tortoises at this site. Implications This study has demonstrated that common handling practices on desert tortoise may cause voiding behaviour. These results suggest that in order to minimise undesirable behavioural responses in studied desert tortoise populations, defined procedures or protocols must be followed by the investigators to reduce contact period to the extent feasible.

Reconsidering Taíno Social Dynamics after Spanish Conquest: Gender and Class in Culture Contact Studies

2004 ◽  
Vol 69 (4) ◽  
pp. 597-626 ◽  
Author(s):  
Kathleen Deagan
Keyword(s):  
Native Americans ◽  
Social Practice ◽  
Social Dynamics ◽  
Analytical Framework ◽  
Cultural Practice ◽  
Culture Contact ◽  
Contact Period ◽  
Cultural Elements ◽  
Mitigating Factors ◽  
Before And After

Despite the fact that the Taíno people of the Caribbean were the first Native Americans to encounter and coexist with Europeans after 1492, there has been almost no archaeology of Taíno response to that encounter. This study explores the reasons for (and consequences of) this neglect, and their larger implications for American contact-period archaeology. It also challenges prevailing historical models of Taíno social disintegration, drawing upon six years of archaeological work at the En Bas Saline site in Haiti, the only extensively excavated Taíno townsite occupied both before and after contact. Our results, organized by a household-scale analytical framework emphasizing Taíno constructions of gender and class, suggest that there were few major alterations to traditional Taíno social practice during the post-contact period, and most of these were related to activities thought to have been the domain of non-elite Taíno men. It is suggested that the relatively nonspecialized gender roles among the Taíno, as well as the clearly differentiated nature of their social classes, may have served as mitigating factors in the disruption of Taíno cultural practice under Spanish domination. This work also reveals a marked Taíno resistance to the incorporation of European cultural elements, which provides a striking contrast to the Spanish patterns documented in contact-era European towns, and underscores the critical importance of incorporating gender relations into studies of culture contact.

Radiocarbon Dating and Dietary Stable Isotope Analysis of Kwaday Dän Ts'inchí

2007 ◽  
Vol 72 (4) ◽  
pp. 719-734 ◽  
Author(s):  
Michael P. Richards ◽  
Sheila Greer ◽  
Lorna T. Corr ◽  
Owen Beattie ◽  
Alexander Mackie ◽  
...  
Keyword(s):  
Radiocarbon Dating ◽  
Isotope Analysis ◽  
Human Remains ◽  
Isotopic Analysis ◽  
High Elevation ◽  
Bone Collagen ◽  
Contact Period ◽  
European Contact ◽  
Ams Dating ◽  
The Individual

We report here on the results of AMS dating and isotopic analysis of the frozen human remains named Kwaday Dän Ts'inchí and associated materials recovered from a glacier located in Northwest British Columbia, Canada in 1999. The isotopic analysis of bone collagen (bulk and single amino acids) from the individual indicates a strongly marine diet, which was unexpected given the location of this find, more than 100 km inland eroding out of a high elevation glacier; however, bulk hair and bone cholesterol isotopic values indicate a shift in diet to include more terrestrial foods in the year before death. The radiocarbon dating is not straightforward, as there are difficulties in determining the appropriate marine correction for the human remains, and the spread of dates on the associated artifacts clearly indicates that this was not a single use site. By combining the most recent date on a robe worn by Kwaday Dän Ts'inchi with direct bone collagen dates we conclude that the individual likely dates to between cal A.D. 1670 to 1850, which is in the pre-(or early) European contact period for this region.

Hertz Contact Force Model With Permanent Indentation in Impact Analysis of Solids

1992 ◽  
Author(s):  
Hamid M. Lankarani ◽  
Parviz E. Nikravesh
Keyword(s):  
Contact Force ◽  
Impact Analysis ◽  
Equations Of Motion ◽  
Solid Particles ◽  
Hertzian Contact ◽  
Contact Period ◽  
Force Model ◽  
Unknown Parameters ◽  
Contact Force Model ◽  
Energy And Momentum

Abstract A continuous analysis method for the direct-central impact of two solid particles is presented. Based on the assumption that local plasticity effects are the sole factor accounting for the dissipation of energy in impact, a Hertzian contact force model with permanent indentation is constructed. Utilizing energy and momentum considerations, the unknown parameters in the model are analytically evaluated in terms of a given coefficient of restitution and velocities before impact. The equations of motion of the two solids may then be integrated forward in time knowing the variation of the contact force during the contact period. For Illustration, an impact of two soft metallic particles is studied.

Overview: Lithic quarries in Pennsylvania: the archaeology of tool stone procurement

2021 ◽  
pp. 019769312110433
Author(s):  
Paul A. Raber
Keyword(s):  
North American ◽  
Contact Period ◽  
Atlantic Region ◽  
Middle Atlantic

This collection of papers, published in numbers 3 and 4 of this volume of North American Archaeologist, reflects recent research into the development of pre-contact period quarries in Pennsylvania and the surrounding Middle Atlantic region.

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