3,048 research outputs found

    First anatomical network analysis of fore- and hindlimb musculoskeletal modularity in bonobos, common chimpanzees, and humans

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    Studies of morphological integration and modularity, and of anatomical complexity in human evolution typically focus on skeletal tissues. Here we provide the first network analysis of the musculoskeletal anatomy of both the fore- and hindlimbs of the two species of chimpanzee and humans. Contra long-accepted ideas, network analysis reveals that the hindlimb displays a pattern opposite to that of the forelimb: Pan big toe is typically seen as more independently mobile, but humans are actually the ones that have a separate module exclusively related to its movements. Different fore- vs hindlimb patterns are also seen for anatomical network complexity (i.e., complexity in the arrangement of bones and muscles). For instance, the human hindlimb is as complex as that of chimpanzees but the human forelimb is less complex than in Pan. Importantly, in contrast to the analysis of morphological integration using morphometric approaches, network analyses do not support the prediction that forelimb and hindlimb are more dissimilar in species with functionally divergent limbs such as bipedal humans

    On the Wigner transform of solutions to the Schrodinger equation

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    In this paper we use theWigner transform to study properties of solutions to the Schr¨odinger equation. In particular, we present an elementary proof of the time decay inequalities for the free particle and harmonic oscillator. Furthermore, we estimate certain localized integral quantities in phase space, involving the Wigner transform of solutions to the Schr¨odinger equation

    Understanding motivational climates in physical education classes: How students perceive learning and performance-oriented climates by teachers and peers

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    This study aimed to translate and validate the Learning and Performance Oriented in Physical Education Climate Questionnaire (LAPOPECQ) in a sample of Portuguese students. Additionally, this study examined if the measurement would be equivalent across samples and gender. For nomological validity, current study examined the relationships of motivational climates oriented by teachers and peers and behavioral regulations in the physical education context. Data from 536 Portuguese students (female = 256) aged 10 and 18 years (M = 13.33; SD = .47) were collected. Participants were involved in regular physical education classes two times per week, according to the Portuguese educational system. The four-correlated factor confirmatory and exploratory model provided acceptable fit to the data. In addition, multigroup analysis showed invariance among groups, namely between calibration and validation samples, and female and male students. Last, significant correlations were found between motivational climates and behavioral regulations as theoretically proposed, confirming nomological validity. The translated LAPOPECQ into Portuguese is a valid instrument assessing students’ perception of motivational climates oriented by teachers and peers.info:eu-repo/semantics/publishedVersio

    The cataclysmic variable orbital period gap: More evident than ever

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    Recently, large and homogeneous samples of cataclysmic variables (CVs) identified by the Sloan Digital Sky Survey (SDSS) were published. In these samples, the famous orbital period gap, which is a dearth of systems in the orbital period range ~2-3 hr and the defining feature of most evolutionary models for CVs, has been claimed not to be clearly present. If true, this finding would completely change our picture of CV evolution. In this Letter we focus on potential differences with respect to the orbital period gap between CVs in which the magnetic field of the white dwarf is strong enough to connect with that of the donor star, so-called polars, and non-polar CVs as the white dwarf magnetic field in polars has been predicted to reduce the strength of angular momentum loss through magnetic braking. We separated the SDSS I-IV sample of CVs into polars and non-polar systems and performed statistical tests to evaluate whether the period distributions are bimodal as predicted by the standard model for CV evolution or not. We confirm the existence of a period gap in the SDSS I-IV sample of non-polar CVs with >98 per cent confidence. The boundaries of the orbital period gap are 147 and 191 minutes, with the lower boundary being different to previously published values (129 min). The orbital period distribution of polars from SDSS I-IV is clearly different and does not show a similar period gap. The SDSS samples as well as previous samples of CVs are consistent with the standard theory of CV evolution. Magnetic braking does indeed seem get disrupted around the fully convective boundary, which causes a detached phase during CV evolution. In polars, the white dwarf magnetic field reduces the strength of magnetic braking and consequently the orbital period distribution of polars does not display an equally profound and extended period gap as non-polars.Comment: Accepted for publication in Astronomy & Astrophysics Letter

    Anatomical Network Comparison of Human Upper and Lower, Newborn and Adult, and Normal and Abnormal Limbs, with Notes on Development, Pathology and Limb Serial Homology vs. Homoplasy

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    How do the various anatomical parts (modules) of the animal body evolve into very different integrated forms (integration) yet still function properly without decreasing the individual's survival? This long-standing question remains unanswered for multiple reasons, including lack of consensus about conceptual definitions and approaches, as well as a reasonable bias toward the study of hard tissues over soft tissues. A major difficulty concerns the non-trivial technical hurdles of addressing this problem, specifically the lack of quantitative tools to quantify and compare variation across multiple disparate anatomical parts and tissue types. In this paper we apply for the first time a powerful new quantitative tool, Anatomical Network Analysis (AnNA), to examine and compare in detail the musculoskeletal modularity and integration of normal and abnormal human upper and lower limbs. In contrast to other morphological methods, the strength of AnNA is that it allows efficient and direct empirical comparisons among body parts with even vastly different architectures (e.g. upper and lower limbs) and diverse or complex tissue composition (e.g. bones, cartilages and muscles), by quantifying the spatial organization of these parts-their topological patterns relative to each other-using tools borrowed from network theory. Our results reveal similarities between the skeletal networks of the normal newborn/adult upper limb vs. lower limb, with exception to the shoulder vs. pelvis. However, when muscles are included, the overall musculoskeletal network organization of the upper limb is strikingly different from that of the lower limb, particularly that of the more proximal structures of each limb. Importantly, the obtained data provide further evidence to be added to the vast amount of paleontological, gross anatomical, developmental, molecular and embryological data recently obtained that contradicts the long-standing dogma that the upper and lower limbs are serial homologues. In addition, the AnNA of the limbs of a trisomy 18 human fetus strongly supports Pere Alberch's ill-named "logic of monsters" hypothesis, and contradicts the commonly accepted idea that birth defects often lead to lower integration (i.e. more parcellation) of anatomical structures

    A simple intra-operative maneuver to decrease a duodenal ulcer hemorrhage temporarily: description and anatomical bases

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    Intraoperative hemostatic suture to treat a bleeding duodenal ulcer is sometimes difficult when there is massive hemorrhage. The aims of this paper are: (1) to describe a practical and easy intraoperative procedure which quickly decreases a massively bleeding duodenal ulcer, allowing the surgeon to identify the bleeding site clearly and obtain definitive hemostasis by suturing the involved vessels with a low risk of common bile duct lesion; and (2) to study in cadavers the anatomical basis of this surgical procedure already successfully performed on patients. Fourteen patients with massive duodenal ulcer bleeding, after unsuccessful endoscopic hemostasis, were operated on and included in this study. After surgical anterior gastroduodenotomy, the surgeon introduced a finger in a downward and forward direction in the bursa omentalis vestibule through the omental foramen. This simple and quick procedure decreased hemorrhage by compressing the gastroduodenal artery against the first part of the posterior surface of the duodenum. Twenty-four fresh blocks of normal tissue were removed from cadavers and were injected with silicone rubber through the common hepatic artery. The distance between the gastroduodenal artery and the omental foramen was measured. With this maneuver the surgeon can clearly see the exact bleeding site and perform an adequate suture with a minor risk of common bile duct lesion
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