Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Slaves”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2Linked to original sources
PubMed2002

Slaving: solvent fluctuations dominate protein dynamics and functions.

Protein motions are essential for function. Comparing protein processes with the dielectric fluctuations of the surrounding solvent shows that they fall into two classes: nonslaved and slaved. Nonslaved processes are independent of the solvent motions; their rates are determined by the protein conformation and vibrational dynamics. Slaved processes are tightly coupled to the solvent; their rates have approximately the same temperature dependence as the rate of the solvent fluctuations, but they are smaller. Because the temperature dependence is determined by the activation enthalpy, we propose that the solvent is responsible for the activation enthalpy, whereas the protein and the hydration shell control the activation entropy through the energy landscape. Bond formation is the prototype of nonslaved processes; opening and closing of channels are quintessential slaved motions. The prevalence of slaved motions highlights the importance of the environment in cells and membranes for the function of proteins.

Energy Transfer↗
PubMed2001

Colony structure of a slavemaking ant. II. Frequency of slave raids and impact on the host population.

The parasite pressure exerted by the slavemaker ant Protomognathus americanus on its host species Leptothorax longispinosus was analyzed demographically and genetically. The origin of slaves found in colonies of the obligate slavemaker was examined with nuclear and mitochondrial DNA markers to make inferences about the frequency and severity of slave raids. Relatedness of enslaved L. longispinosus workers in the same nest was very low, and our data suggest that, on average, each slavemaker nest raids six host colonies per season. Therefore, the influence of slavemaker species on their hosts is much stronger than simple numerical ratios suggest. We also found that slave relatedness was higher in small than in large slavemaker nests; thus, larger nests wield a much stronger influence on the host. We estimated that in the study population, on average, a host nest has a 50% chance of being attacked by a slavemaker colony per year. Free-living Leptothorax colonies in the vicinity of slavemaker nests did not represent the source of slaves working in P. americanus colonies, which suggests that raided nests either do not survive or migrate after being raided. Colony composition and intranest relatedness of free-living L. longispinosus colonies differed markedly between areas with slavemakers and those that are parasite-free. In the presence of slavemakers, host colonies were less likely to be polygynous and had fewer workers and a higher relatedness among worker brood. Host nests with slavemaker neighbors allocated more resources into sexuals, possibly caused by these shifts in nest demography. Finally, enslaved Leptothorax workers in P. americanus nests appeared to be less efficient than their counterparts in free-living colonies. Thus, slavemakers exert a much stronger impact on their hosts than had previously been suspected and represent an unique system to study parasite-host coevolution.

Animals↗
PubMed2004

Heat, sex, and sugar: pregnancy and childbearing in the slave quarters.

This article examines the dynamics of slave fecundity in the antebellum South and analyzes the relationship between the planters' labor requirements and pregnancy on large sugar estates in nineteenth-century Louisiana. In contrast to the cotton states, where the slave population grew, bondspeople in Louisiana's sugar world experienced natural population decrease. This derived in part from imbalanced sex ratios, but as this article explores, it also occurred because of the punishing nature of sugar production that taxed slave women in distinct ways over the entire year. As this article shows, conceptions peaked during the annual harvest season but collapsed at other times because of nutritional stress, overwork, heat, and exhaustion. Addressing the seasonality of slave childbirths, the article posits that workload combined with climatic, ecological, hormonal, nutritional, and lactation factors ultimately shaped the reproductive ecology of American slavery.

Agriculture↗
PubMed2003

Effects of head-slaved navigation and the use of teleports on spatial orientation in virtual environments.

The type of navigation interface in a virtual environment (VE)--head slaved or indirect--determines whether or not proprioceptive feedback stimuli are present during movement. In addition, teleports can be used, which do not provide continuous movement but, rather, discontinuously displace the viewpoint over large distances. A two-part experiment was performed. The first part investigated whether head-slaved navigation provides an advantage for spatial learning in a VE. The second part investigated the role of anticipation when using teleports. The results showed that head-slaved navigation has an advantage over indirect navigation for the acquisition of spatial knowledge in a VE. Anticipating the destination of the teleport prevented disorientation after the displacement to a great extent but not completely. The time that was needed for anticipation increased if the teleport involved a rotation of the viewing direction. This research shows the potential added value of using a head-slaved navigation interface--for example, when using VE for training purposes--and provides practical guidelines for the use of teleports in VE applications.

Adolescent↗
PubMed1992

Mortality in the slave and white populations of Natchitoches Parish, Louisiana, 1850.

A review of mortality from the 1850 census mortality schedules of Natchitoches Parish, Louisiana has provided a snapshot of the health conditions of African-American slaves. The cause of death was abstracted from the mortality schedule and categorized according to the ninth revision of the Manual of the International Classification of Diseases. Children under the age of 9 accounted for 44% of the total mortality. Sixty-four percent of all deaths recorded occurred in the slave population. Sixty-two percent of the slave deaths occurred in the male population. Leading causes of death were helminthiasis, whooping cough, fever, cholera, and pneumonia. Reports of mortality due to Cachexia Africana (dirt eating) among slaves are discussed.

Black or African American↗
PubMed1985

The health of the American slave examined by means of Union Army medical statistics.

The health status of the American slave in the 19th century remains unclear despite extensive historical research. Better knowledge of slave health would provide a clearer picture of the life of the slave, a better understanding of the 19th-century medicine, and possibly even clues to the health problems of modern blacks. This article hopes to contribute to the literature by examining another source of data. Slaves entering the Union Army joined an organization with standardized medical care that generated extensive statistical information. Review of these statistics answers questions about the health of young male blacks at the time American slavery ended.

Black or African American↗
PubMed1978

Some questions related to mechanisms of slave-raids in Amazon-ant Polyergus rufescens Latr.

A new hypothesis concerning the mechanism of the P. rufescens' slave-raids, is proposed. (i) The so-called pseudo-scouting does not contribute to the slave-raids. (ii) The direction of the raid is determined by the random movement of the most easily aroused individuals - the so-called activists. (iii) Once the direction has been set the army marches straight ahead and returns by the same road orienting itself by visual stimuli; single individuals who lag behind can however follow the scent-trial which had been left by the army. (iv) The slave-capturing instinct of the amazons is not directed at the abduction of pupae alone but also and even perhaps primarily at the abduction of mature individuals belonging to the slave-species; that the amazons bring almost only pupae is caused by the fact that the mature individuals offer resistance and are consequently a more troublesome prey.

Animal Communication↗
PubMed2025

Nested Admixture During and After the Trans-Atlantic Slave Trade on the Island of São Tomé.

Human genetic admixture, involving the contact between two or more previously isolated populations, can be a complex process influenced by social dynamics. In this study, we aim to reconstruct complex admixture histories in São Tomé, an island in the Gulf of Guinea where the Portuguese established one of the first plantation-based slave societies. Since the 15th century, migration waves from Africa and Europe, slavery, marooning, and indentured labour led to profound demographic shifts and social stratification on the island. Examining 2.5 million SNPs newly genotyped in 96 São Toméans, we observed patterns of genetic differentiation that were more complex than those of other populations descended from enslaved Africans on either side of the Atlantic. Using local ancestry inference and Identical-by-Descent methods, we identified five genetic clusters in São Tomé and reconstructed shared ancestries between each cluster and 70 African and European population samples, including an extensive sample from the Cabo Verde archipelago. Our findings align with historical records, retracing the major slave trade routes and labour-driven migrations after the abolition of slavery. We also identified gene flow between recently admixed groups that were previously isolated on the island. We call this process, creating multiple layers of genetic ancestry in admixed genomes, nested admixture. We suggest that changing social structures in São Tomé transformed the genetic structure of its population and influenced the admixture process. This study demonstrates how successive admixture and isolation events during and after the Trans-Atlantic Slave Trade shaped extant genetic diversity patterns at local scale in Africa.

Humans↗
PubMedDate not supplied

[The slave family and the introduction of the coffee crop in Bananal, 1801-1829].

"This work studies the importance of family [relationships] among slaves in Bananal (Sao Paulo, Brazil) in the early nineteenth century. Additionally, it examines the effects on the slave family of the introduction and growth of [the] coffee plantation occurring in that region....[It is concluded] that the slave family in Bananal had a cyclical evolution, according to the genesis and development of [the] coffee plantation. Manuscript censuses, especially for the years 1801, 1817 and 1829, are the primary sources on which the analysis is based." (SUMMARY IN ENG)

Agriculture↗
PubMed1982

Osteology of a slave burial population from Barbados, West Indies.

A unique seventeenth-nineteenth century slave cemetery population from Newton plantation, Barbados, allows examination of craniodental characters in relation to ethnohistorical data. Age-at-death estimates suggest life expectancy at birth of 29 years and low infant mortality; historical demography, however, suggests life expectancy of 20 years and very high infant mortality. Tooth decay, bilateral tooth loss, periodontal disease, root hypercementosis, and severe enamel hypoplasia are high in frequency. The teeth yield evidence of such cultural practices as pipe-smoking and incisor mutilation. Several skeletal features reflect periodic near-starvation. Directional and fluctuating dental asymmetry, relative tooth size, and hypoplasia distribution suggest slaves experienced considerable weaning trauma; metabolic stress at this time exceeded that of prenatal and immediate postnatal periods. Odontometrics and dental and cranial nonmetric traits indicate that modern Blacks are intermediate between the ancestral slaves and modern Whites but more similar to the latter, suggesting effects of environmental covariance exceed those of genetic admixture. Nonmetric trait distributions show nonrandom patterns according to area of burial in the cemetery, a possible result of family segregation.

Adolescent↗
PubMed2006

Superlinear scaling in master-slave quantum chemical calculations using in-core storage of two-electron integrals.

We describe the implementation of a parallel, in-core, integral-direct Hartree-Fock and density functional theory code for the efficient calculation of Hartree-Fock wave functions and density functional theory. The algorithm is based on a parallel master-slave algorithm, and the two-electron integrals calculated by a slave are stored in available local memory. To ensure the greatest computational savings, the master node keeps track of all integral batches stored on the different slaves. The code can reuse undifferentiated two-electron integrals both in the wave function optimization and in the evaluation of second-, third-, and fourth-order molecular properties. Superlinear scaling is achieved in a series of test examples, with speedups of up to 55 achieved for calculations run on medium-sized molecules on 16 processors with respect to the time used on a single processor.

Journal Article↗
PubMed2006

Climate change, flow regulation and land-use effects on the hydrology of the Peace-Athabasca-Slave System; findings from the Northern Rivers Ecosystem Initiative.

The Northern Rivers Ecosystem Initiative (NREI) was established in the late 1990s to address important science questions resulting from previous studies undertaken by the Northern Rivers Basin Study (NRBS). This manuscript summarizes the results from a number of reports on hydrologic research conducted on the Peace-Athabasca-Slave river and lake systems. Specific concerns expressed by the NRBS and subsequent NREI focused on how these systems were being affected by climate change, flow regulation and land-use changes. Issues addressed in this report include: the fate of aquatic perched basins within the Peace-Athabasca Delta under historical and future climate trends; the sources of major floods that replenish these basins and how the frequency, magnitude and source areas of such events have changed over time; the synoptic weather patterns and atmospheric teleconnections that are responsible for the generation of major snowmelt runoff that drive major floods; the potential effect that climate and land-use changes might have on basin runoff and delta lake levels; the specific hydro-climatic conditions required to produce major ice-jam floods on the Peace River and how these may be altered by climate change; remote-sensing methods to document delta flooding and vegetation change; and the dual effect of climate and flow regulation on the water levels of Great Slave Lake and how these may affect other nearshore processes, particularly wind seiches, that influence flooding of the Slave River Delta. A review of the major findings and recommendations for future research concludes the report.

Canada↗
PubMed2002

Distribution of HLA alleles in Portugal and Cabo Verde. Relationships with the slave trade route.

HLA-A, -B, and -DR frequencies were analysed in populations from Portugal and the Madeira and Cabo Verde Archipelagos, aiming to characterize their genetic composition. Portuguese settlers colonized both Archipelagos in the 15th and 16th centuries. Madeira received many sub-Saharan slaves to work in the sugar plantations, and Cabo Verde served as a pivotal market in the Atlantic slave trade and was populated by individuals coming from the Senegambia region of the West African coast. The population of Madeira shows the highest genetic diversity and the presence of alleles and haplotypes usually linked to sub-Saharan populations, the haplotypes accounting for 3.5% of the total. Cabo Verde presents typical markers acknowledged to be of European or Ibero-Mediterranean origin, thus revealing the admixture of European settlers with Sub-Saharan slaves. Altogether the number of European haplotypes reaches 15% of the total. The Portuguese population shows a perceivable and significant heterogeneity both in allele and haplotype frequencies, unveiling a differential input of peoples from different origins. A PCA of the populations studied, plus other relevant ones, clearly shows gene heterogeneity in mainland Portugal as well as the differences and relationships between these populations and Madeira and Cabo Verde.

Africa, Western↗
PubMed2002

On the geometry of master-slave synchronization.

In 1990, Pecora and Carroll reported the observation that one can synchronize the orbits of two identical dynamical systems, which may be chaotic, by feeding state variables of one of them to the other one with no feedback, a phenomenon often called master-slave synchronization. We report here some results on the theory of master-slave synchronization for maps and flows, which are all inspired by a similar geometric and coordinate independent point of view to the one introduced in master-slave synchronization by Tresser, Worfolk, and Bass. Our results are variations on the theme that projection often can compensate for expansion.(c) 2002 American Institute of Physics.

Journal Article↗
PubMedDate not supplied

Growth depression and recovery: the remarkable case of American slaves.

Legislation designed to prevent slave smuggling after 1807 created an extra-ordinary set of documents identifying slaves transported in the coastwise trade by name, age, sex height and colour. Slaves fell below the first or second centile of modern height standards as children but recovered during and after adolescence to exceed the 25th centile as adults. This profile differs remarkably from other populations. Poor pre-natal care, early weaning, food supplements that were nutritionally poor and often contaminated, and a heavy disease load thwarted growth during childhood, but the diet improved substantially when young adolescents entered the labour force. The results show that humans have remarkable capacity for catch-up growth.

Adolescent↗
PubMed2000

Geochemistry of the Archean Kam Group, Yellowknife Greenstone Belt, Slave Province, Canada.

The geochemistry and isotope systematics of Archean greenstone belts provide important constraints on the origin of the volcanic rocks and tectonic models for the evolution of Archean cratons. The Kam Group is a approximately 10-km-thick pile of submarine, tholeiitic mafic, and subordinate felsic volcanic rocks erupted between 2712 and 2701 Ma that forms the bulk of the Yellowknife greenstone belt in the dominantly granite-metasedimentary Slave Province. Mafic rocks range from Normal-mid-ocean range basalt-like basalts to slightly light-rare-earth-element-enriched (LREE-enriched) but Nb-depleted basaltic andesites and andesites, whereas dacitic to rhyodacitic felsic rocks are strongly LREE-enriched and highly depleted in Nb. The varepsilonTNd range from +5 to -3 in the mafic to intermediate rocks and from 0 to -5.5 in the felsic rocks. The varepsilonTNd decreases with increasing La/Sm, SiO2 and decreasing Nb/La, suggesting that as the mafic magmas evolved they were contaminated by older basement rocks. Gneissic granitoids >2.9 Ga in age, found at the base of the Kam Group, have varepsilonTNd between -6 and -9 and are excellent candidates for the contaminant. The geochemical and isotopic data, combined with the submarine eruptive setting and field evidence for existing continental basement, support a continental margin rift model for the Kam Group. Similar geochemical-isotopic studies are required on other Slave greenstone belts in order to test evolutionary models for the Slave Province.

Journal Article↗
PubMed2000

Confinement of slave particles in U(1) gauge theories of strongly interacting electrons

We show that slave particles are always confined in U(1) gauge theories of interacting electron systems. Consequently, the low-lying degrees of freedom are different from the slave particles. This is done by constructing a dual formulation of the slave-particle representation in which the no-double-occupancy constraint becomes linear and, hence, soluble. Spin-charge separation, if it occurs, is due to the existence of solitons with fractional quantum numbers in a particular dual action.

Journal Article↗
PubMed2000

Tunneling density of states of high T(c) superconductors: d-wave BCS model versus SU(2) slave-boson model

Motivated by recent experimental measurements of the tunneling characteristics of high T(c) materials using scanning tunneling spectroscopy, we have calculated the I-V and differential conductance curves in the superconducting state at zero temperature. Comparing BCS-like d-wave pairing and the SU(2) slave-boson approach, we find that the slave-boson model can explain the asymmetric background observed in experiments. The slave-boson model also predicts that the height of the conductance peak relative to the background is proportional to the hole doping concentration x, at least for underdoped samples. We also observe the absence of the van Hove singularity, and comment on possible implications.

Journal Article↗