898 research outputs found
Teaching Word Stress: A Curricular Resource For Adult English Language Learners at the High Beginner/Low Intermediate Levels
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 learnersâ awareness and improved pronunciation of North American English word stress. A review of contemporary literature revealed that pronunciation instruction is key to adultsâ 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 authorâs 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
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
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 , where 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 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
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
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 athletesâ throwing velocity
The anterior cribriform plate foramina: from anatomy to surgery
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
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 monthsâ 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
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
- âŠ