875 research outputs found

    Teaching Word Stress: A Curricular Resource For Adult English Language Learners at the High Beginner/Low Intermediate Levels

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    The purpose of this study was to determine what materials were needed to inform the development of a curricular resource contributing to adult English language learners’ awareness and improved pronunciation of North American English word stress. A review of contemporary literature revealed that pronunciation instruction is key to adults’ acquisition of intelligible speech, and that instruction needs to focus foremost on prosodic features that are global to the needs of learners, such as word stress. The author’s curricular resource includes a series of lesson plans and student- centered activities. To guide the development of the resource, the author employed a Communicative Language Teaching approach with principles that embrace the validity of pronunciation instruction and a pedagogical framework of five phases. The resource will add to the small but growing bank of pronunciation instructional resources available for teachers of adult English language learners

    Strong converse for the classical capacity of optical quantum communication channels

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    We establish the classical capacity of optical quantum channels as a sharp transition between two regimes---one which is an error-free regime for communication rates below the capacity, and the other in which the probability of correctly decoding a classical message converges exponentially fast to zero if the communication rate exceeds the classical capacity. This result is obtained by proving a strong converse theorem for the classical capacity of all phase-insensitive bosonic Gaussian channels, a well-established model of optical quantum communication channels, such as lossy optical fibers, amplifier and free-space communication. The theorem holds under a particular photon-number occupation constraint, which we describe in detail in the paper. Our result bolsters the understanding of the classical capacity of these channels and opens the path to applications, such as proving the security of noisy quantum storage models of cryptography with optical links.Comment: 15 pages, final version accepted into IEEE Transactions on Information Theory. arXiv admin note: text overlap with arXiv:1312.328

    Tiny Groups Tackle Byzantine Adversaries

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    A popular technique for tolerating malicious faults in open distributed systems is to establish small groups of participants, each of which has a non-faulty majority. These groups are used as building blocks to design attack-resistant algorithms. Despite over a decade of active research, current constructions require group sizes of O(log⁥n)O(\log n), where nn is the number of participants in the system. This group size is important since communication and state costs scale polynomially with this parameter. Given the stubbornness of this logarithmic barrier, a natural question is whether better bounds are possible. Here, we consider an attacker that controls a constant fraction of the total computational resources in the system. By leveraging proof-of-work (PoW), we demonstrate how to reduce the group size exponentially to O(log⁥log⁥n)O(\log\log n) while maintaining strong security guarantees. This reduction in group size yields a significant improvement in communication and state costs.Comment: This work is supported by the National Science Foundation grant CCF 1613772 and a C Spire Research Gif

    The subperichondrial / subperiosteal dissection in preservation rhinoplasty: how histology can help us to perform better surgeries

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    Aim: The classical dissection plane in rhinoplasty is in the sub-SMAS plane with traumatic dissection of tissues and as a result significant and prolonged postoperative edema, especially in the external approach. A complete subperichondrial/periosteal route has been recently described. It seems to allow for simpler postoperative follow-up than external or closed approach performed in the sub-SMAS plane. However, little is known about the exact histological planes that are really dissected during surgery. Material and methods: Histological examinations of 10 cadavers noses dissected in the so-called subperichondrial/subperiosteal plane were performed. Results: The subperichondrial plane is truly subperichondrial and consists in a dissection under the chondrogenic layer of the perichondrium. Subperichondrial dissection necessitates sharp scrapping to separate the cartilage from the chondrogenic layer. The perichondrium is naturally thicker on the dorsum, which explains why it is easier to begin the dorsal dissection at the W point. Scroll cartilages are consistent and show between 9 and 13 isolated cartilages, most of the time, 1 major and several minors cartilages. Optimal strategy to ease the dissection is discussed Conclusions: The subperichondrial/subperiosteal route, although necessitating significant dissection of the teguments of the nasal pyramid, is respectful of the anatomy of the nasal pyramid. It allows minimal traumatic maneuvers than in the sub-SMAS route, despite of the large dissection performed

    Relationships Between Body Size, Strength, and Power with Throwing Velocity Following a Strength Training Block in High School Water Polo Players

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    A high school strength and conditioning program should ideally improve fitness and develop motor skills in athletes. This could be a targeted goal if research details relationships between sport-specific motor skills and measures of fitness in high school athletes. PURPOSE: To investigate the correlations and predictive relationships (controlling for age) between height, body mass, strength, and power on throwing velocity in male high school water polo athletes after a 4-week strength training block. METHODS: Eighteen water polo athletes (age: 15.50±0.20 years; height: 177.05±1.60 cm; body mass: 74.28±3.70 kg) from one high school program were recruited. Testing occurred in one day; age, height and body mass were recorded first. Strength was measured using combined grip strength (right and left hands) and isometric lower-body strength via a leg/back dynamometer. Power was measured by a vertical jump and 2-kg seated medicine ball throw (MBT). Athletes also threw a water polo ball with maximum effort to measure throwing velocity. Partial correlations and stepwise regression controlling for sex were used to calculate relationships between throwing velocity with body size, strength, and power (pRESULTS: Combined grip strength (r=0.712), leg/back strength (r=0.656), and MBT (r=0.684) all showed significant positive relationships with throwing velocity. Age and combined grip strength predicted throwing velocity with 61.3% explained variance (R2=0.658, adjusted R2=0.613, pCONCLUSION: Strength and conditioning programs targeting upper- and lower-body strength and upper-body power could improve motor skills such as throwing in water polo high school athletes irrespective of age, which provided an indirect metric for maturation. The 4-week training block included exercises targeting these qualities (e.g., squats, presses, pull-ups, hang cleans), and this likely impacted the relationships between strength, power, and throwing velocity seen in this study. Strength and conditioning coaches working with overhead throwing sports at the high school level could incorporate upper- and lower-body strength and power exercises, including exercises that target grip strength, into to their training blocks to enhance their athletes’ throwing velocity

    The anterior cribriform plate foramina: from anatomy to surgery

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    Background: Despite the development of anterior skull base surgery, the anatomy of the nasal bone and anterior cribriform plate remains unclear. A recent study confirmed 2 distinct foramina in the anterior part of the cribriform plate: the ethmoidal slit (ES) and the cribroethmoidal foramen (CF). The aim of this study was to specify their content, their anatomic relationship to the frontal sinus and skull base, and their potential value in skull base surgery. Methods: Dissections were performed on 36 cadaver heads. Macro- and microscopic examinations were carried out. Microcomputed tomography scans contrasted with osmium were performed to identify vessels and nerves. Histology with neural, meningeal, or luteinizing hormone-releasing hormone immunomarkers was performed on the content of the foramina. Finally, endonasal surgical dissections were carried out. Results: The ES and the CF were observed in all cases. They measured a mean of 4.2 and 1.6 mm, respectively. The ES contained dura mater, arachnoid tissues, lymphatics, and the terminal nerve. The CF contained the anterior ethmoidal nerve and artery. This foramen continued forward with the cribroethmoidal groove, which measured a mean of 2.5 mm. This groove was under the frontal sinus and in front of the skull base. We also described a "cribroethmoidal canal" and a "nasal bone foramen." Clinical applications are discussed. Conclusion: The clinical applications of this new anatomic description concern both the cribriform plate and frontal sinus surgeries. Identifying the terminal nerve passing through the ES is a step forward in understanding pheromone recognition in humans

    Isolated hypoglossal palsy due to cervical osteophyte

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    SummaryIntroductionIsolated hypoglossal nerve palsy is rare, and etiological diagnosis is difficult. We report a case of isolated hypoglossal compression by a cervical osteophyte in the hypoglossal canal exit.Case studyAn 86-year-old woman with history of cervical spondylotic myelopathy consulted for a lesion of the free edge of the tongue with impaired elocution. Clinical examination found a bite lesion on the right free edge of the tongue with right lingual amyotrophy and associated left deviation on retraction. Isolated right hypoglossal palsy was diagnosed. Skull base CT found a cervical osteophyte compressing the hypoglossal nerve at the exit from the right hypoglossal canal. Surgery was contra-indicated by the patient's general health status. No motor recovery was observed at 6 months’ follow-up, but the elocution disorders regressed under speech therapy.ConclusionHypoglossal palsy is infrequent, but generally a sign of skull base pathology. History-taking and careful examination guide rational selection of the radiological examinations required for etiological diagnosis

    Closed timelike curves via post-selection: theory and experimental demonstration

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    Closed timelike curves (CTCs) are trajectories in spacetime that effectively travel backwards in time: a test particle following a CTC can in principle interact with its former self in the past. CTCs appear in many solutions of Einstein's field equations and any future quantum version of general relativity will have to reconcile them with the requirements of quantum mechanics and of quantum field theory. A widely accepted quantum theory of CTCs was proposed by Deutsch. Here we explore an alternative quantum formulation of CTCs and show that it is physically inequivalent to Deutsch's. Because it is based on combining quantum teleportation with post-selection, the predictions/retrodictions of our theory are experimentally testable: we report the results of an experiment demonstrating our theory's resolution of the well-known `grandfather paradox.Comment: 5 pages, 4 figure
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