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1.
Arch Phys Med Rehabil ; 105(4): 781-791, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-37490961

RESUMO

OBJECTIVE: To determine the prospective association of pain coping strategies and symptoms of anxiety and depression with work absenteeism in people with upper limb musculoskeletal disorders. DATA SOURCES: A systematic search of PubMed, Web of Science, Embase, Cochrane Library, and Scopus databases was conducted from inception to September 23, 2022. STUDY SELECTION: Prospective observational studies of adults with upper limb musculoskeletal disorders were included. Included studies had to provide data on the association of pain coping strategies (catastrophizing, kinesiophobia, self-efficacy or fear avoidance) or symptoms of anxiety and depression with work absenteeism. DATA EXTRACTION: Study selection, data extraction, and assessment of methodological quality (Newcastle Ottawa Scale) were performed by 2 independent authors. Random-effects models were used for quantitative synthesis. DATA SYNTHESIS: Eighteen studies (n=12,393 participants) were included. Most studies (77.8%) reported at least 1 significant association between 1 or more exposure factors (pain coping strategies or symptoms of anxiety and depression) and work absenteeism. Meta-analyses showed a statistically significant correlation between the exposure factors of catastrophizing (r=0.28, 95% confidence interval [CI]: 0.15 to 0.40; P<.0001) and symptoms of anxiety and depression (r=0.23, 95% CI: 0.10 to 0.34; P=.0003) with work absenteeism. The correlation between self-efficacy and work absenteeism was non-significant (r=0.24, 95% CI: -0.02 to 0.47; P=.0747). CONCLUSIONS: Rehabilitation teams should consider assessing catastrophizing and symptoms of anxiety and depression to identify patients at risk for work absenteeism. Addressing these variables may also be considered in return-to-work programs for individuals with upper limb disorders.


Assuntos
Depressão , Doenças Musculoesqueléticas , Adulto , Humanos , Depressão/epidemiologia , Depressão/diagnóstico , Absenteísmo , Ansiedade/epidemiologia , Ansiedade/diagnóstico , Dor , Doenças Musculoesqueléticas/epidemiologia , Adaptação Psicológica , Extremidade Superior , Estudos Observacionais como Assunto
2.
Opt Express ; 31(6): 9923-9934, 2023 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-37157556

RESUMO

We present a method extending scanning third-order correlator temporal pulse evolution measurement capabilities of high power short pulse lasers to spectral sensitivity within the spectral range exploited by typical chirped pulse amplification systems. Modelling of the spectral response achieved by angle tuning of the third harmonic generating crystal is applied and experimentally validated. Exemplary measurements of spectrally resolved pulse contrast of a Petawatt laser frontend illustrate the importance of full bandwidth coverage for the interpretation of relativistic laser target interaction in particular for the case of solid targets.

3.
Opt Express ; 30(3): 3262-3288, 2022 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-35209589

RESUMO

The investigation of spatio-temporal couplings (STCs) of broadband light beams is becoming a key topic for the optimization as well as applications of ultrashort laser systems. This calls for accurate measurements of STCs. Yet, it is only recently that such complete spatio-temporal or spatio-spectral characterization has become possible, and it has so far mostly been implemented at the output of the laser systems, where experiments take place. In this survey, we present for the first time STC measurements at different stages of a collection of high-power ultrashort laser systems, all based on the chirped-pulse amplification (CPA) technique, but with very different output characteristics. This measurement campaign reveals spatio-temporal effects with various sources, and motivates the expanded use of STC characterization throughout CPA laser chains, as well as in a wider range of types of ultrafast laser systems. In this way knowledge will be gained not only about potential defects, but also about the fundamental dynamics and operating regimes of advanced ultrashort laser systems.

4.
Arch Phys Med Rehabil ; 103(8): 1615-1627, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-34861234

RESUMO

OBJECTIVE: To determine the effects of the cognitive and mental health factors on the outcomes after carpal tunnel release (CTR). DATA SOURCES: Embase, PubMed/MEDLINE, Web of Science, Cumulative Index to Nursing and Allied Health, and Cochrane Central Register of Controlled Trials databases from inception to August 14, 2021. STUDY SELECTION: Randomized controlled trials and observational studies of patients with CTR were included. The included studies aimed to determine the effect of the cognitive (catastrophic thinking, kinesiophobia, self-efficacy) or mental health factors (symptoms of anxiety and depression) on the outcomes at least 3 months post CTR. DATA EXTRACTION: Two independent reviewers performed data extraction and assessed the risk of bias. Data were extracted using a standardized protocol and reporting forms. The risk of bias of the included studies was assessed using the Quality in Prognosis Studies risk-of-bias tool. Random-effects models were used for meta-analysis. DATA SYNTHESIS: A total of 15 studies involving 2599 patients were included in this systematic review. The majority of studies indicate a significant association between the cognitive or mental health factors and outcomes after CTR. Quantitative analysis showed a moderate association of symptoms of depression on symptom severity (n=531; r=0.347; 95% CI, 0.205-0.475; P≤.0001), function (n=386; r=0.307; 95% CI, 0.132-0.464; P=.0008), and pain (n=344; r=0.431; 95% CI, 0.286-0.558; P≤.0001). In general, the risk of bias in the included studies was low. CONCLUSIONS: This systematic review and meta-analysis showed that symptoms of depression have a moderate association with symptom severity, function, and pain after CTR. Symptoms of anxiety, catastrophic thinking, and self-efficacy are also important indicators of poor postsurgery outcomes. Physicians, physical therapists, and occupational therapists should consider evaluating these variables in patients undergoing CTR.


Assuntos
Síndrome do Túnel Carpal , Saúde Mental , Ansiedade/epidemiologia , Síndrome do Túnel Carpal/cirurgia , Cognição , Humanos , Dor
5.
Am J Primatol ; 80(5): e22759, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29664191

RESUMO

Primates are interpreted to be ancestrally adapted to frugivory, although some modern groups show clear adaptations to other diets. Among them, pitheciids stand out for specifically predating seeds. This dietary specialization is known as sclerocarpy and refers to the extraction of seeds from surrounding hard tissues using the anterior dentition followed by the mastication of seeds by the molars. It has been proposed that Callicebus-Pithecia-Chiropotes-Cacajao represent a morphocline of increasingly specialized anatomical traits for sclerocarpic foraging. This study addresses whether there is a sclerocarpic specialization gradient in the mandibular morphology of pitheciids. Finite element analysis (FEA) was used to simulate two biting scenarios and the obtained stress values were compared between different pitheciids. Geometric morphometrics (GM) were used to display the morphological variation of this group. No support was found for the morphocline hypothesis from a biomechanical viewpoint since all pitheciins showed similar stress values and on average Chiropotes rather than Cacajao exhibited the strongest mandible. From a morphological perspective, it was found that there is indeed relative "robusticity" continuum in the pitheciid mandible for some aspects of shape as expected for the morphocline hypothesis, but this gradient could be related to other factors rather than sclerocarpic specialization. The present results are expected to contribute to a better insight regarding the ecomorphological relationship between mandibular morphology and mechanical performance among pitheciids.


Assuntos
Comportamento Alimentar , Mandíbula/anatomia & histologia , Pitheciidae/anatomia & histologia , Adaptação Biológica , Animais , Dieta/veterinária , Frutas , Mastigação
6.
J Hum Evol ; 111: 179-201, 2017 10.
Artigo em Inglês | MEDLINE | ID: mdl-28874270

RESUMO

Platyrrhines are a diverse group of primates that presently occupy a broad range of tropical-equatorial environments in the Americas. However, most of the fossil platyrrhine species of the early Miocene have been found at middle and high latitudes. Although the fossil record of New World monkeys has improved considerably over the past several years, it is still difficult to trace the origin of major modern clades. One of the most commonly preserved anatomical structures of early platyrrhines is the talus. This work provides an analysis of the phenetic affinities of extant platyrrhine tali and their Miocene counterparts through geometric morphometrics and a series of phylogenetic comparative analyses. Geometric morphometrics was used to quantify talar shape affinities, while locomotor mode percentages (LMPs) were used to test if talar shape is associated with locomotion. Comparative analyses were used to test if there was convergence in talar morphology, as well as different models that could explain the evolution of talar shape and size in platyrrhines. Body mass predictions for the fossil sample were also computed using the available articular surfaces. The results showed that most analyzed fossils exhibit a generalized morphology that is similar to some 'generalist' modern species. It was found that talar shape covaries with LMPs, thus allowing the inference of locomotion from talar morphology. The results further suggest that talar shape diversification can be explained by invoking a model of shifts in adaptive peak to three optima representing a phylogenetic hypothesis in which each platyrrhine family occupied a separate adaptive peak. The analyses indicate that platyrrhine talar centroid size diversification was characterized by an early differentiation related to a multidimensional niche model. Finally, the ancestral platyrrhine condition was reconstructed as a medium-sized, generalized, arboreal, quadruped.


Assuntos
Evolução Biológica , Fósseis/anatomia & histologia , Platirrinos/anatomia & histologia , Tálus/anatomia & histologia , Animais , Filogenia , Platirrinos/classificação , Especificidade da Espécie
7.
Am J Phys Anthropol ; 159(2): 325-41, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26472496

RESUMO

OBJECTIVE: The aim was to analyze the relationship between scapular form and function in hominoids by using geometric morphometrics (GM) and finite element analysis (FEA). METHODS: FEA was used to analyze the biomechanical performance of different hominoid scapulae by simulating static postural scenarios. GM was used to quantify scapular shape differences and the relationship between form and function was analyzed by applying both multivariate-multiple regressions and phylogenetic generalized least-squares regressions (PGLS). RESULTS: Although it has been suggested that primate scapular morphology is mainly a product of function rather than phylogeny, our results showed that shape has a significant phylogenetic signal. There was a significant relationship between scapular shape and its biomechanical performance; hence at least part of the scapular shape variation is due to non-phylogenetic factors, probably related to functional demands. DISCUSSION: This study has shown that a combined approach using GM and FEA was able to cast some light regarding the functional and phylogenetic contributions in hominoid scapular morphology, thus contributing to a better insight of the association between scapular form and function.


Assuntos
Escápula/anatomia & histologia , Escápula/fisiologia , Ombro/anatomia & histologia , Ombro/fisiologia , Adulto , Animais , Antropologia Física , Antropometria , Fenômenos Biomecânicos , Feminino , Análise de Elementos Finitos , Hominidae , Humanos , Masculino , Análise Multivariada
8.
Anthropol Anz ; 80(1): 1-12, 2023 Jan 18.
Artigo em Inglês | MEDLINE | ID: mdl-36006051

RESUMO

Wrist shape varies greatly across primates and previous studies indicate that the numerous morphological differences among them are related to a complex mixture of phylogeny and function. However, little is known about whether the variation in these various anatomical differences is linked and to what extent the wrist bones vary independently. Here, we used 3D geometric morphometrics on a sample of extant hominines (Homo sapiens, Pan troglodytes, Gorilla gorilla, and Gorilla beringei), to find the model that best describes the covariation patterns among four of the eight carpals (i.e., capitate, lunate, scaphoid, and trapezium). For this purpose, 15 modular hypotheses were tested using the Covariance Ratio. Results indicate that there is a covariation structure common to all hominines, which corresponds to stronger covariation within each carpal as compared to the covariation between carpals. However, the results also indicate that that there is a degree of codependence in the variation of some carpals, which is unique in humans, chimpanzees, and gorillas, respectively. In humans there is evidence of associated shape changes between the lunate and capitate, and between the scaphoid and trapezium. This covariation between lunate and capitate is also apparent in gorillas, while chimpanzees display the greatest disassociation among carpals, showing low covariation values in all pairwise comparisons. Our analyses indicate that carpals have an important level of variational independence which might suggest a high degree of independent evolvability in the wrists of hominines, and that although weak, the structure of associated changes of these four carpals varies across genera. To our knowledge this is the first report on the patterns of modularity between these four wrist bones in the Homininae and future studies might attempt to investigate whether the anatomical shape associations among carpals are functionally related to locomotion and manipulation.


Assuntos
Ossos do Carpo , Hominidae , Animais , Humanos , Punho/anatomia & histologia , Gorilla gorilla/anatomia & histologia , Pan troglodytes/anatomia & histologia , Hominidae/anatomia & histologia , Ossos do Carpo/anatomia & histologia
9.
Light Sci Appl ; 12(1): 71, 2023 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-36914618

RESUMO

Laser-driven ion sources are a rapidly developing technology producing high energy, high peak current beams. Their suitability for applications, such as compact medical accelerators, motivates development of robust acceleration schemes using widely available repetitive ultraintense femtosecond lasers. These applications not only require high beam energy, but also place demanding requirements on the source stability and controllability. This can be seriously affected by the laser temporal contrast, precluding the replication of ion acceleration performance on independent laser systems with otherwise similar parameters. Here, we present the experimental generation of >60 MeV protons and >30 MeV u-1 carbon ions from sub-micrometre thickness Formvar foils irradiated with laser intensities >1021 Wcm2. Ions are accelerated by an extreme localised space charge field ≳30 TVm-1, over a million times higher than used in conventional accelerators. The field is formed by a rapid expulsion of electrons from the target bulk due to relativistically induced transparency, in which relativistic corrections to the refractive index enables laser transmission through normally opaque plasma. We replicate the mechanism on two different laser facilities and show that the optimum target thickness decreases with improved laser contrast due to reduced pre-expansion. Our demonstration that energetic ions can be accelerated by this mechanism at different contrast levels relaxes laser requirements and indicates interaction parameters for realising application-specific beam delivery.

10.
iScience ; 26(9): 107644, 2023 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-37701811

RESUMO

The Miocene was a key time in the evolution of African ecosystems witnessing the origin of the African apes and the isolation of eastern coastal forests through an expanding arid corridor. Until recently, however, Miocene sites from the southeastern regions of the continent were unknown. Here, we report the first Miocene fossil teeth from the shoulders of the Urema Rift in Gorongosa National Park, Mozambique. We provide the first 1) radiometric ages of the Mazamba Formation, 2) reconstructions of paleovegetation in the region based on pedogenic carbonates and fossil wood, and 3) descriptions of fossil teeth. Gorongosa is unique in the East African Rift in combining marine invertebrates, marine vertebrates, reptiles, terrestrial mammals, and fossil woods in coastal paleoenvironments. The Gorongosa fossil sites offer the first evidence of woodlands and forests on the coastal margins of southeastern Africa during the Miocene, and an exceptional assemblage of fossils including new species.

11.
Sci Rep ; 13(1): 20611, 2023 11 23.
Artigo em Inglês | MEDLINE | ID: mdl-37996453

RESUMO

The recently observed FLASH effect describes the observation of normal tissue protection by ultra-high dose rates (UHDR), or dose delivery in a fraction of a second, at similar tumor-killing efficacy of conventional dose delivery and promises great benefits for radiotherapy patients. Dedicated studies are now necessary to define a robust set of dose application parameters for FLASH radiotherapy and to identify underlying mechanisms. These studies require particle accelerators with variable temporal dose application characteristics for numerous radiation qualities, equipped for preclinical radiobiological research. Here we present the DRESDEN PLATFORM, a research hub for ultra-high dose rate radiobiology. By uniting clinical and research accelerators with radiobiology infrastructure and know-how, the DRESDEN PLATFORM offers a unique environment for studying the FLASH effect. We introduce its experimental capabilities and demonstrate the platform's suitability for systematic investigation of FLASH by presenting results from a concerted in vivo radiobiology study with zebrafish embryos. The comparative pre-clinical study was conducted across one electron and two proton accelerator facilities, including an advanced laser-driven proton source applied for FLASH-relevant in vivo irradiations for the first time. The data show a protective effect of UHDR irradiation up to [Formula: see text] and suggests consistency of the protective effect even at escalated dose rates of [Formula: see text]. With the first clinical FLASH studies underway, research facilities like the DRESDEN PLATFORM, addressing the open questions surrounding FLASH, are essential to accelerate FLASH's translation into clinical practice.


Assuntos
Neoplasias , Prótons , Animais , Humanos , Dosagem Radioterapêutica , Peixe-Zebra , Neoplasias/radioterapia , Radiobiologia
12.
Biology (Basel) ; 11(4)2022 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-35453766

RESUMO

Static, developmental, and evolutionary variation are different sources of morphological variation which can be quantified using morphometrics tools. In the present study we have carried out a comparative multiple level study of integration (i.e., static, developmental, and evolutionary) to acquire insight about the relationships that exist between different integration levels, as well as to better understand their involvement in the evolutionary processes related to the diversification of Drosophila's wing shape. This approach was applied to analyse wing evolution in 59 species across the whole genus in a large dataset (~10,000 wings were studied). Static integration was analysed using principal component analysis, thus providing an integration measurement for overall wing shape. Developmental integration was studied between wing parts by using a partial least squares method between the anterior and posterior compartments of the wing. Evolutionary integration was analysed using independent contrasts. The present results show that all Drosophila species exhibit strong morphological integration at different levels. The strong integration and overall similarities observed at multiple integration levels suggest a shared mechanism underlying this variation, which could result as consequence of genetic drift acting on the wing shape of Drosophila.

13.
Sci Rep ; 12(1): 21488, 2022 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-36509788

RESUMO

Application experiments with laser plasma-based accelerators (LPA) for protons have to cope with the inherent fluctuations of the proton source. This creates a demand for non-destructive and online spectral characterization of the proton pulses, which are for application experiments mostly spectrally filtered and transported by a beamline. Here, we present a scintillator-based time-of-flight (ToF) beam monitoring system (BMS) for the recording of single-pulse proton energy spectra. The setup's capabilities are showcased by characterizing the spectral stability for the transport of LPA protons for two beamline application cases. For the two beamline settings monitored, data of 122 and 144 proton pulses collected over multiple days were evaluated, respectively. A relative energy uncertainty of 5.5% (1[Formula: see text]) is reached for the ToF BMS, allowing for a Monte-Carlo based prediction of depth dose distributions, also used for the calibration of the device. Finally, online spectral monitoring combined with the prediction of the corresponding depth dose distribution in the irradiated samples is demonstrated to enhance applicability of plasma sources in dose-critical scenarios.

14.
R Soc Open Sci ; 8(6): 210836, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-34234959

RESUMO

Obtaining accurate values for body segment parameters (BSPs) is fundamental in many biomechanical studies, particularly for gait analysis. Convex hulling, where the smallest-possible convex object that surrounds a set of points is calculated, has been suggested as an effective and time-efficient method to estimate these parameters in extinct animals, where soft tissues are rarely preserved. We investigated the effectiveness of convex hull BSP estimation in a range of extant mammals, to inform the potential future usage of this technique with extinct taxa. Computed tomography scans of both the skeleton and skin of every species investigated were virtually segmented. BSPs (the mass, position of the centre of mass and inertial tensors of each segment) were calculated from the resultant soft tissue segments, while the bone segments were used as the basis for convex hull reconstructions. We performed phylogenetic generalized least squares and ordinary least squares regressions to compare the BSPs calculated from soft tissue segments with those estimated using convex hulls, finding consistent predictive relationships for each body segment. The resultant regression equations can, therefore, be used with confidence in future volumetric reconstruction and biomechanical analyses of mammals, in both extinct and extant species where such data may not be available.

15.
Nat Ecol Evol ; 5(6): 808-819, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33795855

RESUMO

Quantifying speciation times during human evolution is fundamental as it provides a timescale to test for the correlation between key evolutionary transitions and extrinsic factors such as climatic or environmental change. Here, we applied a total evidence dating approach to a hominin phylogeny to estimate divergence times under different topological hypotheses. The time-scaled phylogenies were subsequently used to perform ancestral state reconstructions of body mass and phylogenetic encephalization quotient (PEQ). Our divergence-time estimates are consistent with other recent studies that analysed extant species. We show that the origin of the genus Homo probably occurred between 4.30 and 2.56 million years ago. The ancestral state reconstructions show a general trend towards a smaller body mass before the emergence of Homo, followed by a trend towards a greater body mass. PEQ estimations display a general trend of gradual but accelerating encephalization evolution. The obtained results provide a rigorous temporal framework for human evolution.


Assuntos
Hominidae , Animais , Evolução Biológica , Humanos , Filogenia
16.
PLoS One ; 15(1): e0227362, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31978063

RESUMO

The cranium is an anatomically complex structure. One source of its complexity is due to its modular organization. Cranial modules are distinct and partially independent units that interact substantially during ontogeny thus generating morphological integration. Artificial Cranial Deformation (ACD) occurs when the human skull is intentionally deformed, through the use of different deforming devices applied to the head while it is developing. Hence, ACD provides an interesting example to assess the degree to which biomechanical perturbations of the developing neurocranium impact on the degree of morphological integration in the skull as a whole. The main objective of this study was to assess how ACD affects the morphological integration of the skull. This was accomplished by comparing a sample of non-deformed crania and two sets of deformed crania (i.e. antero-posterior and oblique). Both developmental and static modularity and integration were assessed through Generalized Procrustes Analysis by considering the symmetric and asymmetric components of variation in adults, using 3D landmark coordinates as raw data. The presence of two developmental modules (i.e. viscero and neurocranium) in the skull was tested. Then, in order to understand how ACD affects morphological integration, the covariation pattern between the neuro and viscerocranium was examined in antero-posterior, oblique and non-deformed cranial categories using Partial Least-Squares. The main objective of this study was to assess how ACD affects the morphological integration of the skull. This was accomplished by comparing a sample of deformed (i.e. antero-posterior and oblique) and non-deformed crania. Hence, differences in integration patterns were compared between groups. The obtained results support the modular organization of the human skull in the two analyzed modules. The integration analyses show that the oblique ACD style differentially affects the static morphological integration of the skull by increasing the covariance between neuro and viscerocranium in a more constrained way than in antero-posterior and non-deformed skulls. In addition, the antero-posterior ACD style seems to affect the developmental integration of the skull by directing the covariation pattern in a more defined manner as compared to the other cranial categories.


Assuntos
Ossos Faciais/anatomia & histologia , Base do Crânio/anatomia & histologia , Arqueologia , Evolução Biológica , Chile , Humanos
17.
Sci Rep ; 10(1): 6793, 2020 04 22.
Artigo em Inglês | MEDLINE | ID: mdl-32322020

RESUMO

An on-going debate concerning the dietary adaptations of archaic hominins and early Homo has been fuelled by contradictory inferences obtained using different methodologies. This work presents an extensive comparative sample of 30 extant primate species that was assembled to perform a morpho-functional comparison of these taxa with 12 models corresponding to eight fossil hominin species. Finite Element Analysis and Geometric Morphometrics were employed to analyse chewing biomechanics and mandible morphology to, firstly, establish the variation of this clade, secondly, relate stress and shape variables, and finally, to classify fossil individuals into broad ingesta related hardness categories using a support vector machine algorithm. Our results suggest that some hominins previously assigned as hard food consumers (e.g. the members of the Paranthropus clade) in fact seem to rely more strongly on soft foods, which is consistent with most recent studies using either microwear or stable isotope analyses. By analysing morphometric and stress results in the context of the comparative framework, we conclude that in the hominin clade there were probably no hard-food specialists. Nonetheless, the biomechanical ability to comminute harder items, if required as fallback option, adds to their strategy of increased flexibility.


Assuntos
Adaptação Fisiológica/fisiologia , Dieta , Alimentos , Fósseis , Mandíbula/anatomia & histologia , Mastigação/fisiologia , Animais , Evolução Biológica , Análise de Elementos Finitos , Hominidae , Arcada Osseodentária/anatomia & histologia , Arcada Osseodentária/fisiologia , Mandíbula/fisiologia , Primatas/anatomia & histologia , Primatas/classificação , Primatas/fisiologia , Crânio/anatomia & histologia , Crânio/fisiologia , Máquina de Vetores de Suporte
18.
Sci Rep ; 10(1): 3526, 2020 02 26.
Artigo em Inglês | MEDLINE | ID: mdl-32103129

RESUMO

Inferring the locomotor behaviour of the last common ancestor (LCA) of humans and African apes is still a divisive issue. An African great-ape-like ancestor using knuckle-walking is still the most parsimonious hypothesis for the LCA, despite diverse conflicting lines of evidence. Crucial to this hypothesis is the role of the centrale in the hominoid wrist, since the fusion of this bone with the scaphoid is among the clearest morphological synapomorphies of African apes and hominins. However, the exact functional significance of this fusion remains unclear. We address this question by carrying out finite element simulations of the hominoid wrist during knuckle-walking by virtually generating fused and unfused morphologies in a sample of hominoids. Finite element analysis was applied to test the hypothesis that a fused scaphoid-centrale better withstands the loads derived from knuckle-walking. The results show that fused morphologies display lower stress values, hence supporting a biomechanical explanation for the fusion as a functional adaptation for knuckle-walking. This functional interpretation for the fusion contrasts with the current inferred positional behaviour of the earliest hominins, thus suggesting that this morphology was probably retained from an LCA that exhibited knuckle-walking as part of its locomotor repertoire and that was probably later exapted for other functions.


Assuntos
Evolução Biológica , Articulação Metacarpofalângica/fisiologia , Osso Escafoide/fisiologia , Caminhada/fisiologia , Animais , Hominidae , Humanos
19.
J R Soc Interface ; 15(146)2018 09 26.
Artigo em Inglês | MEDLINE | ID: mdl-30257926

RESUMO

The talus is one of the most commonly preserved post-cranial elements in the platyrrhine fossil record. Talar morphology can provide information about postural adaptations because it is the anatomical structure responsible for transmitting body mass forces from the leg to the foot. The aim of this study is to test whether the locomotor behaviour of fossil Miocene platyrrhines could be inferred from their talus morphology. The extant sample was classified into three different locomotor categories and then talar strength was compared using finite-element analysis. Geometric morphometrics were used to quantify talar shape and to assess its association with biomechanical strength. Finally, several machine-learning (ML) algorithms were trained using both the biomechanical and morphometric data from the extant taxa to infer the possible locomotor behaviour of the Miocene fossil sample. The obtained results show that the different locomotor categories are distinguishable using either biomechanical or morphometric data. The ML algorithms categorized most of the fossil sample as arboreal quadrupeds. This study has shown that a combined approach can contribute to the understanding of platyrrhine talar morphology and its relationship with locomotion. This approach is likely to be beneficial for determining the locomotor habits in other fossil taxa.


Assuntos
Fósseis , Locomoção , Aprendizado de Máquina , Platirrinos/fisiologia , Tálus/fisiologia , Algoritmos , Animais , Evolução Biológica , Fenômenos Biomecânicos , Análise de Elementos Finitos , Matemática , Modelos Anatômicos , Filogenia , Crânio/anatomia & histologia
20.
Sci Rep ; 7(1): 8364, 2017 08 21.
Artigo em Inglês | MEDLINE | ID: mdl-28827696

RESUMO

The relationship between primate mandibular form and diet has been previously analysed by applying a wide array of techniques and approaches. Nonetheless, most of these studies compared few species and/or infrequently aimed to elucidate function based on an explicit biomechanical framework. In this study, we generated and analysed 31 Finite Element planar models of different primate jaws under different loading scenarios (incisive, canine, premolar and molar bites) to test the hypothesis that there are significant differences in mandibular biomechanical performance due to food categories and/or food hardness. The obtained stress values show that in primates, hard food eaters have stiffer mandibles when compared to those that rely on softer diets. In addition, we find that folivores species have the weakest jaws, whilst omnivores have the strongest mandibles within the order Primates. These results are highly relevant because they show that there is a strong association between mandibular biomechanical performance, mandibular form, food hardness and diet categories and that these associations can be studied using biomechanical techniques rather than focusing solely on morphology.


Assuntos
Fenômenos Biomecânicos , Dieta , Comportamento Alimentar , Mandíbula/anatomia & histologia , Mandíbula/fisiologia , Primatas , Animais
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