Large-scale,millennial-length temperature reconstructions from tree-rings

Over the past two decades, the dendroclimate community has produced various annually resolved, warm season temperature reconstructions for the extratropical Northern Hemisphere. Here we compare these tree-ring based reconstructions back to 831 CE and present a set of basic metrics to provide guidance for non-specialists on their interpretation and use. We specifically draw attention to (i) the imbalance between (numerous) short and (few) long site chronologies incorporated into the hemispheric means, (ii) the beneficial effects of including maximum latewood density chronologies in the recently published reconstructions, (iii) a decrease in reconstruction covariance prior to 1400 CE, and (iv) the varying amplitudes and trends of reconstructed temperatures over the past 1100 years. Whereas the reconstructions agree on several important features, such as warmth during medieval times and cooler temperatures in the 17th and 19th centuries, they still exhibit substantial differences during 13th and 14th centuries. We caution users who might consider combining the reconstructions through simple averaging that all reconstructions share some of the same underlying tree-ring data, and provide four recommendations to guide future efforts to better understand past millennium temperature variability.     

Human skeletal remains from Mumba Rock Shelter,Northern Tanzania

During their expeditions in Northern Tanzania in 1934/38, Ludwig and Margit Kohl-Larsen (discoverer of Eyasi and Garusi hominids)excavated i. a. the Mumba Rock Shelter. This important excavation yielded human skeletal remains of 18 individuals. The most relevant results of the morphological analyses are presented here. According to the affinities and absolute dating (hominid IX, 3700 B. C. ), the present study supports recent indications of the presence of Negroid groups in East Africa at an early stage in Later Stone Age times.     

Relationship of lower limb height to sitting height in black populations of Africa and the United States.

This article examines a recently reported generalization. Materials from more than a score of invetigations are drawn upon. These materials show there is not a substantial research base for the claim that interbreeding in the United States between black people of African ancestry and white people of European ancestry has resulted in increased lower limb height relative to sitting height.     

Aging leads to inferior Achilles tendon mechanics and altered ankle function in rodents

Spontaneous rupture of the Achilles tendon is increasingly common in the middle aged population. However, the cause for the particularly high incidence of injury in this age group is not well understood. Therefore, the objective of this study was to identify age-specific differences in the Achilles tendon-muscle complex using an animal model. Functional measures were performed in vivo and tissues were harvested following euthanasia for mechanical, structural, and histological analysis from young, middle aged, and old rats. Numerous alterations in tendon properties were detected across age groups, including inferior material properties (maximum stress, modulus) with increasing age. Differences in function were also observed, as older animals exhibited increased ankle joint passive stiffness and decreased propulsion force during locomotion. Macroscale differences in tendon organization were not observed, although cell density and nuclear shape did vary between age groups. Muscle fiber size and type distribution were not notably affected by age, indicating that other factors may be more responsible for age-specific Achilles tendon rupture rates. This study improves our understanding of the role of aging in Achilles tendon biomechanics and ankle function, and helps provide a potential explanation for the disparate incidence of Achilles tendon ruptures in varying age groups.     

Espasticidad tras ictus: ¿la edad es un factor de riesgo? Estudio observacional de la espasticidad en pacientes neurovasculares en una serie retrospectiva de dos centros

ObjectiveApproximately one third of patients who have suffered a stroke develop spasticity. Since clinical observations that spasticity in the elderly population is lower after stroke, and disagreement about risk factors between different authors, an analysis is performed on the variables that influence the development of spasticity.The objective of the study is to determine the how many factors influence spasticity outcome, and the prevalence of spasticity in patients who have suffered a stroke and require intensive rehabilitation treatment.MethodA retrospective assessment was carried out on a total of 554 patients from two neurorehabilitation centres. A record was made of sociodemographic data, aetiology, type and location of stroke, motor and sensory deficits, language and swallowing impairment, incontinence, cognitive and mood state. Spasticity levels at admission and at the third month were studied in 462 patients using the Ashworth scale. Multivariate regression analyses were used to assess the risk factors for spasticity present at the third month after stroke.ResultsThe mean age of the patients was 67.3 years, of which 67.1% were men, and with ischemic aetiology in 76.5%. On admission 31.4% of patients had spasticity, and this increased to 54.8% at the 3^rd month. The absolute risk factor for spasticity was motor index (OR 1.04; 95% CI 1.03-1.05). When this factor was omitted, the variables with predictive ability were: age less than 75 years (OR 0.52; 95% CI 0.30-0.90), sensory impairment (OR 0.66; 95% CI 0.37-1.20), and lower Barthel index score (OR 1.02; 95% CI 1.01-1.03). There was no significant relationship for gender, physiopathological mechanism (ischaemic/haemorrhagic), stroke location, aphasia, or cognitive impairment.ConclusionThe prevalence of spasticity in stroke at third month of follow-up was 54.8%. Motor index is the independent predictor of spasticity. Patients younger than 75 years old, with sensory impairment and low Barthel index score are more likely to develop spasticity.     

Aspects of the distribution of HbS in the United States

Frequencies of HbS obtained by several screening clinics are analyzed for age, sex, and location effects. All seem to be present in some form, though age and sex effects may be conditional on location. An attempt is made to elaborate the common observation of increasing frequency with age. This is shown to be the result of differences in fertility favoring the normal. A simulation which íncludes 25% admixture was done. The results indicate a genetically relevant New World experience for the population to be about 9–12 generations with the heterozygote having fitness of 0.96–0.99.     

Variation in dental occlusion and arches among melanesians of bougainville island,papua New Guinea. I. Methods,age changes,sex differences and population comparisons

Population studies of malocclusion lack comparability because of the subjective criteria employed in the definition of malocclusion. Alternatively, individual characteristics of occlusion can be quantified and compared within and between populations. Measurements were taken from the dental cases of 319 male an 359 female Melanesians from Bougainville, Papua New Guinea. The cross-sectional age changes from 12 to 68 years of age included an increase in intermolar arch width, a decrease in arch length and intercanine arch width, and increased crowding and malalignment. Neither age nor sex accounted for a large proportion of the differences among individuals. When compared to industrialized groups, the Bougainville population had a slight reduction in variance for most characteristics. Only the sagittal molar relationship was markedly less variable on Bougainville. The results emphasize that a quantitative evaluation of individual occlusal variables may reveal differences within and between populations not detected when simple malocclusion frequencies are reported.     

Upper extremity kinematic and kinetic adaptations during a fatiguing repetitive task

Repetitive low-force contractions are common in the workplace and yet can lead to muscle fatigue and work-related musculoskeletal disorders. The current study aimed to investigate potential motion adaptations during a simulated repetitive light assembly work task designed to fatigue the shoulder region, focusing on changes over time and age-related group differences. Ten younger and ten older participants performed four 20-min task sessions separated by short breaks. Mean and variability of joint angles and scapular elevation, joint net moments for the shoulder, elbow, and wrist were calculated from upper extremity kinematics recorded by a motion tracking system. Results showed that joint angle and joint torque decreased across sessions and across multiple joints and segments. Increased kinematic variability over time was observed in the shoulder joint; however, decreased kinematic variability over time was seen in the more distal part of the upper limb. The changes of motion adaptations were sensitive to the task-break schedule. The results suggested that kinematic and kinetic adaptations occurred to reduce the biomechanical loading on the fatigued shoulder region. In addition, the kinematic and kinetic responses at the elbow and wrist joints also changed, possibly to compensate for the increased variability caused by the shoulder joint while still maintaining task requirements. These motion strategies in responses to muscle fatigue were similar between two age groups although the older group showed more effort in adaptation than the younger in terms of magnitude and affected body parts.     

Morphology of the facets of the proximal Tarsi bones from an ancient population

The analysis of morphological variation of tali and calcanei articular surfaces from “S'Illot des Porros” (Majorca, 2430±200 BP) has been made. It indicates the high frequency of extensions of the talocrural and subtalar surfaces, which are shown to be produced not only by a high level of stress on the bones. The presence of the sulcus tali facet in most cases could indicate, however, a greater degree of lateral movement of the foot.