661 research outputs found

    Quantifier elimination in C*-algebras

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    The only C*-algebras that admit elimination of quantifiers in continuous logic are C,C2\mathbb{C}, \mathbb{C}^2, C(C(Cantor space)) and M2(C)M_2(\mathbb{C}). We also prove that the theory of C*-algebras does not have model companion and show that the theory of Mn(On+1)M_n(\mathcal {O_{n+1}}) is not \forall\exists-axiomatizable for any n2n\geq 2.Comment: More improvements and bug fixes. To appear in IMR

    Spherical frame projections for visualising joint range of motion, and a complementary method to capture mobility data

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    Quantifying joint range of motion (RoM), the reachable poses at a joint, has many applications in research and clinical care. Joint RoM measurements can be used to investigate the link between form and function in extant and extinct animals, to diagnose musculoskeletal disorders and injuries or monitor rehabilitation progress. However, it is difficult to visually demonstrate how the rotations of the joint axes interact to produce joint positions. Here, we introduce the spherical frame projection (SFP), which is a novel 3D visualisation technique, paired with a complementary data collection approach. SFP visualisations are intuitive to interpret in relation to the joint anatomy because they ‘trace’ the motion of the coordinate system of the distal bone at a joint relative to the proximal bone. Furthermore, SFP visualisations incorporate the interactions of degrees of freedom, which is imperative to capture the full joint RoM. For the collection of such joint RoM data, we designed a rig using conventional motion capture systems, including live audio-visual feedback on torques and sampled poses. Thus, we propose that our visualisation and data collection approach can be adapted for wide use in the study of joint function

    In vivo and ex vivo range of motion in the fire salamander Salamandra salamandra

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    Joint range of motion (RoM) analyses are fundamental to our understanding of how an animal moves throughout its ecosystem. Recent technological advances allow for more detailed quantification of this RoM (e.g. including interaction of degrees of freedom) both in ex vivo joints and in vivo experiments. Both types of data have been used to draw comparisons with fossils to reconstruct locomotion. Salamanders are often used as analogues for early tetrapod locomotion; testing such hypotheses requires an in-depth analysis of salamander joint RoM. Here, we provide a detailed dataset of the ex vivo ligamentous rotational joint RoM in the hindlimb of the fire salamander Salamandra salamandra, using a new method for collecting and visualising joint RoM. We also characterise in vivo joint RoM used during walking, via scientific rotoscoping and compare the in vivo and ex vivo data. In summary, we provide (1) a new method for joint RoM data experiments and (2) a detailed analysis of both in vivo and ex vivo data of salamander hindlimbs, which can be used for comparative studies

    Effects of antenatal dexamethasone treatment on glucocorticoid receptor and calcyon gene expression in the prefrontal cortex of neonatal and adult common marmoset monkeys

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    BACKGROUND: Synthetic glucocorticoids such as dexamethasone (DEX) are commonly used to promote fetal lung maturation in at-risk preterm births, but there is emerging evidence of subsequent neurobehavioral abnormalities in these children e.g. problems with inattention/hyperactivity. However, molecular pathways mediating effects of glucocorticoid overexposure on motor and cognitive development are poorly understood. METHODS: In this study with common marmoset monkeys, we investigated for neonatal and adulthood effects of antenatal DEX treatment on the expression of the corticosteroid receptors and also calcyon, a risk gene for attention-deficit/hyperactivity disorder, in the prefrontal cortex (PFC). Pregnant marmosets were exposed to DEX (5 mg/kg body weight) or vehicle during early (days 42-48) or late (days 90-96) stages of the 144-day pregnancy. RESULTS: In neonates, relative to controls, glucocorticoid receptor (GR) mRNA levels were significantly reduced after the late DEX treatment in the medial, orbital and dorsal PFC and after the early DEX treatment in the dorsal PFC. The early DEX exposure, specifically, resulted in significant reduction in calcyon mRNA expression in the medial, orbital, dorsal and lateral PFC relative to controls. Mineralocorticoid receptor (MR) mRNA levels were not significantly affected by DEX treatment. In adults, PFC GR, calcyon, and MR mRNA levels were not significantly affected by early or late prenatal DEX treatment. CONCLUSION: These findings indicate that antenatal DEX treatment could lead to short-term alterations in PFC expression of the GR and calcyon genes, with possible neurodevelopmental functional consequences

    The dynamic role of the ilio-sacral joint in jumping frogs

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    A striking feature among jumping frogs is a sharp pelvic bend about the ilio-sacral (IS) joint, unique to anurans. Although this sagittal plane hinge has been interpreted as crucial for the evolution of jumping, its mechanical contribution has not been quantified. Using a model based on Kassina maculata and animated with kinematics from prior experiments, we solved the ground contact dynamics in MuJoCo enabling inverse dynamics without force plate measurements. We altered the magnitude, speed and direction of IS extension (leaving remaining kinematics unaltered) to determine its role in jumping. Ground reaction forces (GRFs) matched recorded data. Prior work postulated that IS rotation facilitates jumping by aligning the torso with the GRF. However, our simulations revealed that static torso orientation has little effect on GRF due to the close proximity of the IS joint with the COM, failing to support the ‘torso alignment’ hypothesis. Rather than a postural role, IS rotation has a dynamic function whereby angular acceleration (i) influences GRF direction to modulate jump direction and (ii) increases joint loading, particularly at the ankle and knee, perhaps increasing tendon elastic energy storage early in jumps. Findings suggest that the pelvic hinge mechanism is not obligatory for jumping, but rather crucial for the fine tuning of jump trajectory, particularly in complex habitats

    Inverse dynamic modelling of jumping in the red-legged running frog, Kassina maculata

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    Although the red-legged running frog, Kassina maculata, is secondarily a walker/runner, it retains the capacity for multiple locomotor modes, including jumping at a wide range of angles (nearly 70 deg). Using simultaneous hind limb kinematics and single-foot ground reaction forces, we performed inverse dynamics analyses to calculate moment arms and torques about the hind limb joints during jumping at different angles in K. maculata. We show that forward thrust is generated primarily at the hip and ankle, while body elevation is primarily driven by the ankle. Steeper jumps are achieved by increased thrust at the hip and ankle and greater downward rotation of the distal limb segments. Because of its proximity to the GRF vector, knee posture appears to be important in controlling torque directions about this joint and, potentially, torque magnitudes at more distal joints. Other factors correlated with higher jump angles include increased body angle in the preparatory phase, faster joint openings and increased joint excursion, higher ventrally directed force, and greater acceleration and velocity. Finally, we demonstrate that jumping performance in K. maculata does not appear to be compromised by presumed adaptation to walking/running. Our results provide new insights into how frogs engage in a wide range of locomotor behaviours and the multi-functionality of anuran limbs

    Cranial Neuralgias in Children and Adolescents A review of the literature

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    Cranial neuralgias are a well-established cause of headache-related morbidity in the adult population. These disorders are poorly studied in general due to their relative rarity, particularly in children and adolescents, and they are likely underdiagnosed in these populations. Recognizing these disorders and differentiating them from more common headache disorders, such as migraine, is important, as secondary disease is common. This review will cover the basic epidemiology, diagnosis, and treatment of trigeminal, occipital, glossopharyngeal and other, less common, cranial neuralgias. We have reviewed pediatric case reports of these conditions. For trigeminal neuralgia, the most common of these disorders, we have compiled the clinical features and treatment response of previous reports

    ICES coordinated acoustic survey of ICES divisions IIIa, IVa, IVb AND Via (North) 2002 Results and long term trends

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    Six surveys were carried out during late June and July covering most of the continental shelf north of 54oN in the North Sea and to the west of Scotland to a northern limit of 62oN. The eastern edge of the survey area was bounded by the Norwegian and Danish, Swedish and German coasts, and to the west by the shelf edge between 200 and 400 m depth. The surveys are reported individually in the report of the planning group for herring surveys, and a combined report has been prepared from the data from all surveys. The combined survey results provide spatial distributions of herring abundance by number and biomass at age by statistical rectangle; and distributions of mean weight and fraction mature at age. The estimates of North Sea autumn spawning herring are consistent with previous years at 2.9 million tonnes and 17,200 million herring. The survey also shows two exceptional year classes of herring (the 1998 and 2000 year classes) in the North Sea, which is consistent with the observation of exceptionally large year classes observed in the MIK and IBTS surveys. The estimates of Western Baltic spring spawning herring SSB are 255,000 tonnes and 2.9 millions (Table 2) and show a large increase compared with the previous year. The Western Baltic survey produces a rather noisy signal but the indications are of a stock that is higher now than between 1996 to 2000. The West of Scotland survey estimates of 548,000 tonnes and 2,900 million and shows the high 1995 year class again this year. The 1998 year class now (3 ring) is also a large one. Total adult mortality shows much lower mortality than last year (0.1 compared to 0.5 ) but the mean mortality over the last 4 years has been 0.3: this is consistent with the 2002 assessment that the stock is lightly exploited. The overall time series of abundance by age from 1989 to 2002 are summarised by simple models describing the spatial distribution over time. The changes over time with latitude, longitude and area occupied are compared with changes in abundance

    ICES coordinated acoustic survey of ICES divisions IIIa, IVa, IVb AND Via (North) 2002 Results and long term trends

    Get PDF
    Six surveys were carried out during late June and July covering most of the continental shelf north of 54oN in the North Sea and to the west of Scotland to a northern limit of 62oN. The eastern edge of the survey area was bounded by the Norwegian and Danish, Swedish and German coasts, and to the west by the shelf edge between 200 and 400 m depth. The surveys are reported individually in the report of the planning group for herring surveys, and a combined report has been prepared from the data from all surveys. The combined survey results provide spatial distributions of herring abundance by number and biomass at age by statistical rectangle; and distributions of mean weight and fraction mature at age. The estimates of North Sea autumn spawning herring are consistent with previous years at 2.9 million tonnes and 17,200 million herring. The survey also shows two exceptional year classes of herring (the 1998 and 2000 year classes) in the North Sea, which is consistent with the observation of exceptionally large year classes observed in the MIK and IBTS surveys. The estimates of Western Baltic spring spawning herring SSB are 255,000 tonnes and 2.9 millions (Table 2) and show a large increase compared with the previous year. The Western Baltic survey produces a rather noisy signal but the indications are of a stock that is higher now than between 1996 to 2000. The West of Scotland survey estimates of 548,000 tonnes and 2,900 million and shows the high 1995 year class again this year. The 1998 year class now (3 ring) is also a large one. Total adult mortality shows much lower mortality than last year (0.1 compared to 0.5 ) but the mean mortality over the last 4 years has been 0.3: this is consistent with the 2002 assessment that the stock is lightly exploited. The overall time series of abundance by age from 1989 to 2002 are summarised by simple models describing the spatial distribution over time. The changes over time with latitude, longitude and area occupied are compared with changes in abundance
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