2,451 research outputs found

    Malignant peripheral nerve sheath tumor of the cervical vagus nerve in a neurofibromatosis type 1 patient - An unusual presentation

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    Malignant peripheral nerve sheath tumors (MPNST’S) of the head and neck comprise 2% to 6% of head and neck sarcomas. These tumors may arise as sporadic variants or in patients with neurofibromatosis (NF). Development of these MPNST’s is one of the serious complications of neurofibromatosis type 1(NF1). To our knowledge there are only two reported cases of MPNST’s arising in the cervical vagal nerve, occurring in NF1 patients. We present here an NF1 patient who developed an MPNST of the cervical vagus nerve and presented only with a cervical swelling and hoarseness

    Automated optimization of a reduced layer 5 pyramidal cell model based on experimental data.

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    The construction of compartmental models of neurons involves tuning a set of parameters to make the model neuron behave as realistically as possible. While the parameter space of single-compartment models or other simple models can be exhaustively searched, the introduction of dendritic geometry causes the number of parameters to balloon. As parameter tuning is a daunting and time-consuming task when performed manually, reliable methods for automatically optimizing compartmental models are desperately needed, as only optimized models can capture the behavior of real neurons. Here we present a three-step strategy to automatically build reduced models of layer 5 pyramidal neurons that closely reproduce experimental data. First, we reduce the pattern of dendritic branches of a detailed model to a set of equivalent primary dendrites. Second, the ion channel densities are estimated using a multi-objective optimization strategy to fit the voltage trace recorded under two conditions - with and without the apical dendrite occluded by pinching. Finally, we tune dendritic calcium channel parameters to model the initiation of dendritic calcium spikes and the coupling between soma and dendrite. More generally, this new method can be applied to construct families of models of different neuron types, with applications ranging from the study of information processing in single neurons to realistic simulations of large-scale network dynamics

    Event sponsorship by alcoholic and non-alcoholic drinks businesses in India

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    Purpose – This paper aims to examine event sponsorship decision making by the Indian drinks industry, comparing the non-alcoholic and alcoholic drinks sectors. Design/methodology/approach – Data regarding event sponsorship activity, perceptions of event sponsorship, motives to sponsor, form of investment and structure of sponsorship was obtained from a sample of 61 drinks producers in India through a questionnaire. Mann-Whitney and logistic regression were employed to compare the alcoholic and the non-alcoholic sectors. Findings – The results suggest that the alcohol and non-alcohol drinks sectors sponsored a similar level of events, but in investment volume terms, sponsorship from the non-alcoholic sector is far greater than that of the alcoholic sector. While the two sectors are similar in many ways, the emphasis placed on certain motives for sponsoring events was different, with alcoholic drinks businesses placing greater importance on reaching niche audiences and increasing media coverage than non-alcoholic ones. Research limitations/implications – A limited number of areas of the sponsorship decision-making were covered, yet the study provides insights into the decision making of one of the key sponsoring industries: the drinks industry. Practical implications – Securing sponsorship is becoming more difficult and complex. By understanding how sponsors make decisions, including potential variations between companies within an industry, event organisers will be in a better position to tailor sponsorship proposals, enhancing the likelihood of obtaining the desired sponsorship contracts. Originality/value – Most sponsor decision-making research focuses on how sponsorship decisions can be improved so that they work better for the sponsor. This paper, in contrast, emphasises that by understanding how clients make decisions (i.e. sponsors), sellers (i.e. the sponsored) will be in a better position to win over competition and secure the desired sponsorship deals

    Topology optimized permanent magnet systems

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    Topology optimization of permanent magnet systems consisting of permanent magnets, high permeability iron and air is presented. An implementation of topology optimization for magnetostatics is discussed and three examples are considered. First, the Halbach cylinder is topology optimized with iron and an increase of 15% in magnetic efficiency is shown, albeit with an increase of 3.8 pp. in field inhomogeneity - a value compared to the inhomogeneity in a 16 segmented Halbach cylinder. Following this a topology optimized structure to concentrate a homogeneous field is shown to increase the magnitude of the field by 111% for the chosen dimensions. Finally, a permanent magnet with alternating high and low field regions is considered. Here a Λcool\Lambda_\mathrm{cool} figure of merit of 0.472 is reached, which is an increase of 100% compared to a previous optimized design.Comment: 10 pages, 10 figure

    Bound electron nonlinearity beyond the ionization threshold

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    Although high field laser-induced ionization is a fundamental process underlying many applications, there have been no absolute measurements of the nonlinear polarizability of atoms and molecules in the presence of ionization. Such information is crucial, for example, for understanding the propagation of high intensity ultrashort pulses in matter. Here, we present absolute space- and time-resolved measurements of the ultrafast laser-driven nonlinear polarizability in argon, krypton, xenon, nitrogen, and oxygen up to an ionization fraction of a few percent. These measurements enable determination of the non-perturbative bound electron nonlinearity well beyond the ionization threshold, where it is found to be approximately linear in intensity

    Stability of Resonant Opto-Mechanical Oscillators

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    We theoretically study the frequency stability of an opto-mechanical radio frequency oscillator based on resonant interaction of two optical and one mechanical modes of the same optical microcavity. A generalized expression for the phase noise of the oscillator is derived using Langevin formalism and compared to the phase noise of existing electronic oscillators.Comment: 6 pages, 1 figur

    Education Interrupted: The Growing Use of Suspensions in New York City's Public Schools

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    The New York Civil Liberties Union analyzed 10 years of discipline data from New York City schools, and found that:*The total number of suspensions in New York City grew at an alarming rate over the last decade: One out of every 14 students was suspended in 2008-2009; in 1999-2000 it was one in 25. In 2008-2009, this added up to more than 73,000 suspensions.*Students with disabilities are four times more likely to be suspended than students without disabilities.*Black students, who comprise 33 percent of the student body, served 53 percent of suspensions over the past 10 years. *Black students with disabilities represent more than 50 percent of suspended students with disabilities.*Black students also served longer suspensions on average and were more likely to be suspended for subjective misconduct, like profanity and insubordination.*Suspensions are becoming longer: More than 20 percent of suspensions lasted more than one week in 2008-2009, compared to 14 percent in 1999-2000. The average length of a long-term suspension is five weeks (25 school days).*Between 2001 and 2010, the number of infractions listed in the schools' Discipline Code increased by 49 percent. During that same period, the number of zero tolerance infractions, which mandate a suspension regardless of the individual facts of the incident, increased by 200 percent.*Thirty percent of suspensions occur during March and June of each school year
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