385 research outputs found

    An Energy-conscious Transport Protocol for Multi-hop Wireless Networks

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    We present a transport protocol whose goal is to reduce power consumption without compromising delivery requirements of applications. To meet its goal of energy efficiency, our transport protocol (1) contains mechanisms to balance end-to-end vs. local retransmissions; (2) minimizes acknowledgment traffic using receiver regulated rate-based ïŹ‚ow control combined with selected acknowledgements and in-network caching of packets; and (3) aggressively seeks to avoid any congestion-based packet loss. Within a recently developed ultra low-power multi-hop wireless network system, extensive simulations and experimental results demonstrate that our transport protocol meets its goal of preserving the energy efficiency of the underlying network.Defense Advanced Research Projects Agency (NBCHC050053

    Bounded decision-making, teachers’ reflection, and organisational learning: how research can inform teachers and teaching

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    Despite numerous efforts to align educational practice more closely with findings from educational research, there is little clarity about how educational practitioners can, in principle, use research. We propose a conceptualisation based on how research can contribute to practitioners’ thinking: specifically, our framework proposes that research can inform bounded decision‐making, teachers’ reflection and organisational learning. Practitioners can also use research without being aware that they are doing so. We argue that this conceptualisation of research use has potential to inform researchers and practitioner

    Avoidable 30‐day readmissions in patients undergoing vascular surgery

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    Background: Vascular surgery has one of the highest unplanned 30-day readmission rates of all surgical specialities. The degree to which these may be avoidable and the optimal strategies to reduce their occurrence is unknown. The aim of this study was to identify and classify avoidable 30-day readmissions in patients undergoing vascular surgery in order to plan targeted interventions to reduce their occurrence, improve outcomes and reduce cost. Methods: A retrospective analysis of discharges over a 12-month period from a single tertiary vascular unit was performed. A multidisciplinary panel conducted a manual case note review to identify and classify those 30-day unplanned emergency readmissions deemed avoidable. Results: An unplanned 30-day readmission occurred in 72/885 (8.1%) admissions. These unplanned readmissions were deemed avoidable in 50.0% (36/72) and were most frequently due to unresolved medical issues (19/36, 52.8%) and inappropriate admission with the potential for outpatient management (7/36, 19.4%). A smaller number were due to inadequate social care provision (4/36, 11.1%) and the occurrence of other avoidable adverse events (4/36, 11.1%). Conclusion: Half of all 30-day readmissions in vascular patients are potentially avoidable. Multidisciplinary coordination of inpatient care and the transition from hospital to community care following discharge need to be improved

    At the upper palaeolithic - mesolithic boundary: Revision of the human remains from riparo fredian (MOLAZZANA, LUCCA, ITALY)

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    Pleistocene and early Holocene human fossils in Tuscany are very few and poorly described. Any new information is thus an important contribution to our knowledge of the peopling of this region. Here we present a revision of the human fossil remains from the Riparo Fredian, a site located in Garfagnana and first published by Boschian et al., (1995). The authors described the human remains of the site pointing out the presence of 39 isolated human teeth (19 maxillary and 20 mandibular) and "fragments of one adult humerus, of a child's femur and of a youngster's ulna", considered as belonging to six individuals at least. A reanalysis of the human remains indicated that several specimens were incorrectly identified. It was thus deemed important to revise the identification of each fossil and their interpretation. The revision of human remains from Riparo Fredian has led to several changes in their anatomical identification with respect to the original publications. Of the 39 teeth previously described, the analysis revealed that two of them belonged to non-human animals, and 18 were mistakenly identified. A new, correct identification is provided for each of them. Also, two human teeth not described in the original papers have been identified. The anatomical identification of the post-cranial remains has been confirmed for two out of the three specimens. The minimum number of individuals, based on the dental remains, is confirmed as at least 5, but most probably 6, although with a different allocation of teeth to individual specimens. The age at death of the six individuals has also been reassessed, indicating the presence of two infants, two young adults and two mature adults

    At the upper Palaeolithic – Mesolithic boundary : revision of the human remains from Riparo Fredian (Molazzana, Lucca, Italy)

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    Abstract: Pleistocene and early Holocene human fossils in Tuscany are very few and poorly described. Any new information is thus an important contribution to our knowledge of the peopling of this region. Here we present a revision of the human fossil remains from the Riparo Fredian, a site located in Garfagnana and first published by Boschian et al., (1995). The authors described the human remains of the site pointing out the presence of 39 isolated human teeth (19 maxillary and 20 mandibular) and “fragments of one adult humerus, of a child's femur and of a youngster’s ulna”, considered as belonging to six individuals at least. A reanalysis of the human remains indicated that several specimens were incorrectly identified. It was thus deemed important to revise the identification of each fossil and their interpretation. The revision of human remains from Riparo Fredian has led to several changes in their anatomical identification with respect to the original publications. Of the 39 teeth previously described, the analysis revealed that two of them belonged to non-human animals, and 18 were mistakenly identified. A new, correct identification is provided for each of them. Also, two human teeth not described in the original papers have been identified. The anatomical identification of the post-cranial remains has been confirmed for two out of the three specimens. The minimum number of individuals, based on the dental remains, is confirmed as at least 5, but most probably 6, although with a different allocation of teeth to individual specimens. The age at death of the six individuals has also been reassessed, indicating the presence of two infants, two young adults and two mature adults

    A gigantic new dinosaur from Argentina and the evolution of the sauropod hind foot

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    Titanosauria is an exceptionally diverse, globally-distributed clade of sauropod dinosaurs that includes the largest known land animals. Knowledge of titanosaurian pedal structure is critical to understanding the stance and locomotion of these enormous herbivores and, by extension, gigantic terrestrial vertebrates as a whole. However, completely preserved pedes are extremely rare among Titanosauria, especially as regards the truly giant members of the group. Here we describe Notocolossus gonzalezparejasi gen. et sp. nov. from the Upper Cretaceous of Mendoza Province, Argentina. With a powerfully-constructed humerus 1.76m in length, Notocolossus is one of the largest known dinosaurs. Furthermore, the complete pes of the new taxon exhibits a strikingly compact, homogeneous metatarsus - seemingly adapted for bearing extraordinary weight - and truncated unguals, morphologies that are otherwise unknown in Sauropoda. The pes underwent a near-progressive reduction in the number of phalanges along the line to derived titanosaurs, eventually resulting in the reduced hind foot of these sauropods.Fil: Gonzalez Riga, Bernardo Javier. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico Conicet - Mendoza. Instituto Argentino de NivologĂ­a, GlaciologĂ­a y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de NivologĂ­a, GlaciologĂ­a y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de NivologĂ­a, GlaciologĂ­a y Ciencias Ambientales; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales. Laboratorio de Dinosaurios.; ArgentinaFil: Lamanna, Matthew C.. University of Pittsburgh at Johnstown; Estados UnidosFil: Ortiz David, Leonardo Daniel. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales. Laboratorio de Dinosaurios.; Argentina. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico Conicet - Mendoza. Instituto Argentino de NivologĂ­a, GlaciologĂ­a y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de NivologĂ­a, GlaciologĂ­a y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de NivologĂ­a, GlaciologĂ­a y Ciencias Ambientales; ArgentinaFil: Calvo, Jorge Orlando. Universidad Nacional del Comahue; ArgentinaFil: Coria, Juan Pedro. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales. Laboratorio de Dinosaurios.; Argentin

    Catheter manipulation analysis for objective performance and technical skills assessment in transcatheter aortic valve implantation

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    Purpose Transcatheter aortic valve implantation (TAVI) demands precise and efficient handling of surgical instruments within the confines of the aortic anatomy. Operational performance and dexterous skills are critical for patient safety, and objective methods are assessed with a number of manipulation features, derived from the kinematic analysis of the catheter/guidewire in fluoroscopy video sequences. Methods A silicon phantom model of a type I aortic arch was used for this study. Twelve endovascular surgeons, divided into two experience groups, experts (n=6) and novices (n=6), performed cannulation of the aorta, representative of valve placement in TAVI. Each participant completed two TAVI experiments, one with conventional catheters and one with the Magellan robotic platform. Video sequences of the fluoroscopic monitor were recorded for procedural processing. A semi-automated tracking software provided the 2D coordinates of the catheter/guidewire tip. In addition, the aorta phantom was segmented in the videos and the shape of the entire catheter was manually annotated in a subset of the available video frames using crowdsourcing. The TAVI procedure was divided into two stages, and various metrics, representative of the catheter’s overall navigation as well as its relative movement to the vessel wall, were developed. Results Experts consistently exhibited lower values of procedure time and dimensionless jerk, and higher average speed and acceleration than novices. Robotic navigation resulted in increased average distance to the vessel wall in both groups, a surrogate measure of safety and reduced risk of embolisation. Discrimination of experience level and types of equipment was achieved with the generated motion features and established clustering algorithms. Conclusions Evaluation of surgical skills is possible through the analysis of the catheter/guidewire motion pattern. The use of robotic endovascular platforms seems to enable more precise and controlled catheter navigation

    In situ observations on the dentition and oral cavity of the Neanderthal skeleton from Altamura (Italy)

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    The Neanderthal specimen from Lamalunga Cave, near Altamura (Apulia, Italy), was discovered during a speleological survey in 1993. The specimen is one of the most complete fossil hominins in Europe and its state of preservation is exceptional, although it is stuck in calcareous concretions and the bones are mostly covered by calcite depositions. Nevertheless, it is possible to carry out some observations on craniodental features that have not previously been described. In this work, we present an account of the oral cavity, made possible by the use of a videoscope, which allowed us to reach some hidden parts of the mandible and palate. This is the first detailed overview of the teeth and maxillary bones of the Neanderthal skeleton from Altamura. The dentition is almost complete. However, two teeth (upper right P3 and upper left M1) were lost ante mortem and four teeth (lower right I1 and P3 and lower left I1 and I2) were lost most probably post mortem. Dental wear is marked. The erupted M3s and the inversion of the compensating curve of Wilson in the M1s and M2s but not in the M3s suggest that the individual is fully adult, but not old. Although most of the teeth have their roots exposed for several millimeters, the periodontal bone appears to be in good condition overall, except in correspondence of the two ante-mortem tooth losses. X-rays of the anterior teeth show a periapical lesion, probably linked to the advanced dental wear. We also observed a weak expression of taurodontism in the posterior dentition and the presence of a retromolar space, features consistent with an attribution to the Neanderthal hypodigm; this attribution is also supported by aspects of the cranial morphology, the morphometric analysis of the scapula and preliminary mtDNA data. There is also a well-developed palatine torus, to the best of our knowledge a feature not previously described in Neanderthals
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