485 research outputs found
Homo sapiens in the Americas. Overview of the earliest human expansion in the new world
Although it is widely recognised that America was the last continent to be populated by our species, researchers' views on various aspects of this process (e.g. the period in which it occurred, the area from which the colonizing populations came, the number of dispersal waves and the routes taken by these migrations) differ significantly. In this paper, we review both classical data and more recent findings from various research fields - including geology, paleoecology, archaeology, skeletal biology, and genetics - that may shed light on the dynamics of the colonization of the American continent, according to a critical reappraisal of the various hypotheses and models that have been advanced over time to explain this process
Concrete and abstract concepts in school age children
The aim of this study is to highlight what kind of information distinguishes abstract and concrete conceptual knowledge in different aged children. A familiarity-rating task has shown that 8-year-olds judged concrete concepts as very familiar while abstract concepts were judged as much less familiar with ratings increasing substantially from age 10 to age 12, according to literature showing that abstract terms are not mastered until adolescence (Schwanenflugel, 1991). The types of relation elicited by abstract and concrete concepts during development were investigated in an association production task. At all considered age levels, concrete concepts mainly activated attributive and thematic relations as well as, to a much lesser extent, taxonomic relations and stereotypes. Abstract concepts, instead, elicited mainly thematic relations and, to a much lesser extent, examples and taxonomic relations. The patterns of relations elicited were already differentiated by age 8, becoming more specific in abstract concepts with age
Pre‐historic eating patterns in Latin America and protective effects of plant‐based diets on cardiovascular risk factors
In this review, we present the contributions to nutrition science from Latin American native peoples and scientists, appreciated from a historic point of view since pre‐historic times to the modern age. Additionally, we present epidemiological and clinical studies on the area of plant‐based diets and their relation with the prevention and treatment of cardiovascular diseases conducted in recent decades, and we discuss challenges and perspectives regarding aspects of nutrition in the region
Mitochondrial DNA Suggests a Western Eurasian origin for Ancient (Proto-) Bulgarians
Ancient (proto-) Bulgarians have long been thought to as a Turkic population. However, evidence found in the past three decades show that this is not the case. Until now, this evidence does not include ancient mitochondrial DNA (mtDNA) analysis. In order to fill this void, we have collected human remains from the VIII-X century AD located in three necropolises in Bulgaria: Nojarevo (Silistra region) and Monastery of Mostich (Shumen region), both in Northeast Bulgaria and Tuhovishte (Satovcha region) in Southwest Bulgaria. The phylogenetic analysis of 13 ancient DNA samples (extracted from teeth) identified 12 independent haplotypes, which we further classified into mtDNA haplogroups found in present-day European and Western Eurasian populations. Our results suggest a Western Eurasian matrilineal origin for proto-Bulgarians as well as a genetic similarity between proto- and modern Bulgarians. Our future work will provide additional data which will further clarify proto-Bulgarian origins; thereby adding new clues to current understanding of European genetic evolution
High sensitivity of a histological method in the detection of low-dosage illicit treatment with 17b-estradiol in male calves.
Avaliação e manejo da dor em pacientes idosos com e sem demência
Persistent pain is a frequent health problem in the elderly. Its prevalence ranges from 45% to 80%. Chronic diseases, such as depression, cardiovascular disease, cancer and osteoporosis have a higher prevalence in aged individuals and increase the risk of developing chronic pain. The presence of pain is known to be associated with sleep disorders in these patients, as well as functional impairment, decreased sociability and greater use of the health system, with consequent increase in costs. Alzheimer's disease patients seem to have a normal pain discriminative capacity and they may probably have weaker emotional and affective experience of pain when compared to other types of dementia. Many patients have language deficits and thus cannot properly describe its characteristics. In more advanced cases, it becomes even difficult to determine whether pain is present or not. Therefore, the evaluation of these patients should be performed in a systematic way. There are three ways to measure the presence of pain: by direct questioning (self-report), by direct behavioral observation and by interviews with caregivers or informants. In recent years, many pain scales and questionnaires have been published and validated specifically for the elderly population. Some are specific to patients with cognitive decline, allowing pain evaluation to be conducted in a structured and reproducible way. The next step is to determine the type of painful syndrome and discuss the bases of the pharmacological management, the use of multiple medications and the presence of comorbidities demand the use of smaller doses and impose contra-indications against some drug classes. A multiprofessional approach is the rule in the management of these patients.Dor persistente é um problema de saúde frequente no idoso e sua prevalência varia de 45 a 80%. Doenças crônicas, como depressão, distúrbios cardiovasculares, câncer e osteoporose tem alta prevalência em indivíduos idosos e aumentam o risco de desenvolver dor crônica. Nestes indivíduos, a presença de dor está associada a distúrbios do sono, prejuízo funcional, diminuição da sociabilidade e maior procura dos serviços de saúde, com o consequente aumento dos custos de saúde. Pacientes com Alzheimer têm uma capacidade discriminativa dolorosa normal e uma experiência afetiva e emocional da dor mais atenuada quando comparados com outros tipos de demência. Muitos pacientes têm déficits de linguagem e não podem descrever adequadamente as características de sua dor. Em casos avançados, torna-se difícil determinar se a dor está realmente presente ou não. Desta forma, a avaliação destes doentes deve ser realizada de forma sistemática. Há três formas de se avaliar a dor: questionários diretos, observação direta do comportamento ou entrevistas diretas com os cuidadores ou informantes. Nos últimos anos muitas escalas e questionários para dor foram publicados e validados especificamente para a população idosa. Alguns são específicos para pacientes com declínio cognitivo, permitindo que a evolução da dor possa ser conduzida de uma forma estruturada e reprodutível. O passo seguinte é se determinar o tipo de síndrome dolorosa e se discutir as bases do manejo farmacológico. O uso de múltiplas medicações e a presença de comorbidades exige o uso de pequenas doses e impõem contra-indicações para algumas classes de drogas. A abordagem multidisciplinar é a regra no seguimento a longo prazo destes doentes
Successful extraction of insect DNA from recent copal inclusions: limits and perspectives
Insects entombed in copal, the sub-fossilized resin precursor of amber, represent a potential source of genetic data for extinct and extant, but endangered or elusive, species. Despite several studies demonstrated that it is not possible to recover endogenous DNA from insect inclusions, the preservation of biomolecules in fossilized resins samples is still under debate. In this study, we tested the possibility of obtaining endogenous ancient DNA (aDNA) molecules from insects preserved in copal, applying experimental protocols specifically designed for aDNA recovery. We were able to extract endogenous DNA molecules from one of the two samples analyzed, and to identify the taxonomic status of the specimen. Even if the sample was found well protected from external contaminants, the recovered DNA was low concentrated and extremely degraded, compared to the sample age. We conclude that it is possible to obtain genomic data from resin-entombed organisms, although we discourage aDNA analysis because of the destructive method of extraction protocols and the non-reproducibility of the results
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