660 research outputs found

    A novel spectral-efficient resource allocation approach for NOMA-based full-duplex systems

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    © 2019 IEEE. This paper investigates the coexistence of non- orthogonal multiple access (NOMA) and full-duplex (FD), where the NOMA successive interference cancellation technique is applied simultaneously to both uplink (UL) and downlink (DL) transmissions in the same time-frequency resource block. Specifically, we jointly optimize the user association (UA) and power control to maximize the overall sum rate, subject to user-specific quality-of-service and total transmit power constraints. To be spectrally-efficient, we introduce the tensor model to optimize the UL users' decoding order and the DL users' clustering, which results in a mixed-integer non- convex problem. For solving this problem, we first relax the binary variables to be continuous, and then propose a low-complexity design based on the combination of the inner convex approximation framework and the penalty method. Numerical results show that the proposed algorithm significantly outperforms the conventional FD-based schemes, FD-NOMA and its half-duplex counterpart with random UA

    Joint Power Control and User Association for NOMA-Based Full-Duplex Systems

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    © 1972-2012 IEEE. This paper investigates the coexistence of non-orthogonal multiple access (NOMA) and full-duplex (FD) to improve both spectral efficiency (SE) and user fairness. In such a scenario, NOMA based on the successive interference cancellation technique is simultaneously applied to both uplink (UL) and downlink (DL) transmissions in an FD system. We consider the problem of jointly optimizing user association (UA) and power control to maximize the overall SE, subject to user-specific quality-of-service and total transmit power constraints. To be spectrally-efficient, we introduce the tensor model to optimize UL users' decoding order and DL users' clustering, which results in a mixed-integer non-convex problem. For practically appealing applications, we first relax the binary variables and then propose two low-complexity designs. In the first design, the continuous relaxation problem is solved using the inner convex approximation framework. Next, we additionally introduce the penalty method to further accelerate the performance of the former design. For a benchmark, we develop an optimal solution based on brute-force search (BFS) over all possible cases of UAs. It is demonstrated in numerical results that the proposed algorithms outperform the conventional FD-based schemes and its half-duplex counterpart, as well as yield data rates close to those obtained by BFS-based algorithm

    Vortices in polariton OPO superfluids

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    This chapter reviews the occurrence of quantised vortices in polariton fluids, primarily when polaritons are driven in the optical parametric oscillator (OPO) regime. We first review the OPO physics, together with both its analytical and numerical modelling, the latter being necessary for the description of finite size systems. Pattern formation is typical in systems driven away from equilibrium. Similarly, we find that uniform OPO solutions can be unstable to the spontaneous formation of quantised vortices. However, metastable vortices can only be injected externally into an otherwise stable symmetric state, and their persistence is due to the OPO superfluid properties. We discuss how the currents charactering an OPO play a crucial role in the occurrence and dynamics of both metastable and spontaneous vortices.Comment: 40 pages, 16 figure

    Intraventricular glioneuronal tumor with disseminated lesions at diagnosis - a case report -

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    A 55-year-old man presented with a large tumor in his lateral ventricles. Magnetic resonance imaging revealed disseminated lesions in the third and fourth ventricles at the time of diagnosis. The patient underwent a partial removal of the tumor in the lateral ventricles. Histologically, the surgical specimens showed glioneuronal differentiation with ganglion or ganglioid cells, Rosenthal fibers, oligodendroglia-like honeycomb appearances, a spongy pattern, perivascular pseudorosettes, and many hyalinized blood vessels. Papillary structure was not observed. The neuronal component showed a moderately high labeling index of Ki-67/MIB-1. We diagnosed this tumor as atypical intraventricular glioneuronal tumor. The disseminated lesions disappeared after chemoradiation therapy with temozolomide, and the residual tumors in the lateral ventricles remained stable for 3 years after the surgery. We discuss the pathological diagnosis, therapy and clinical course with review of the literatures

    Back reaction, covariant anomaly and effective action

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    In the presence of back reaction, we first produce the one-loop corrections for the event horizon and Hawking temperature of the Reissner-Nordstr\"om black hole. Then, based on the covariant anomaly cancelation method and the effective action technique, the modified expressions for the fluxes of gauge current and energy momentum tensor, due to the effect of back reaction, are obtained. The results are consistent with the Hawking fluxes of a (1+1)-dimensional blackbody at the temperature with quantum corrections, thus confirming the robustness of the covariant anomaly cancelation method and the effective action technique for black holes with back reaction.Comment: 17 page

    Clinical patterns in asthma based on proximal and distal airway nitric oxide categories

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    <p>Abstract</p> <p>Background</p> <p>The exhaled nitric oxide (eNO) signal is a marker of inflammation, and can be partitioned into proximal [J'aw<sub>NO </sub>(nl/s), maximum airway flux] and distal contributions [CA<sub>NO </sub>(ppb), distal airway/alveolar NO concentration]. We hypothesized that J'aw<sub>NO </sub>and CA<sub>NO </sub>are selectively elevated in asthmatics, permitting identification of four inflammatory categories with distinct clinical features.</p> <p>Methods</p> <p>In 200 consecutive children with asthma, and 21 non-asthmatic, non-atopic controls, we measured baseline spirometry, bronchodilator response, asthma control and morbidity, atopic status, use of inhaled corticosteroids, and eNO at multiple flows (50, 100, and 200 ml/s) in a cross-sectional study design. A trumpet-shaped axial diffusion model of NO exchange was used to characterize J'aw<sub>NO </sub>and CA<sub>NO</sub>.</p> <p>Results</p> <p>J'aw<sub>NO </sub>was not correlated with CA<sub>NO</sub>, and thus asthmatic subjects were grouped into four eNO categories based on upper limit thresholds of non-asthmatics for J'aw<sub>NO </sub>(≥ 1.5 nl/s) and CA<sub>NO </sub>(≥ 2.3 ppb): Type I (normal J'aw<sub>NO </sub>and CA<sub>NO</sub>), Type II (elevated J'aw<sub>NO </sub>and normal CA<sub>NO</sub>), Type III (elevated J'aw<sub>NO </sub>and CA<sub>NO</sub>) and Type IV (normal J'aw<sub>NO </sub>and elevated CA<sub>NO</sub>). The rate of inhaled corticosteroid use (lowest in Type III) and atopy (highest in Type II) varied significantly amongst the categories influencing J'aw<sub>NO</sub>, but was not related to CA<sub>NO</sub>, asthma control or morbidity. All categories demonstrated normal to near-normal baseline spirometry; however, only eNO categories with increased CA<sub>NO </sub>(III and IV) had significantly worse asthma control and morbidity when compared to categories I and II.</p> <p>Conclusions</p> <p>J'aw<sub>NO </sub>and CA<sub>NO </sub>reveal inflammatory categories in children with asthma that have distinct clinical features including sensitivity to inhaled corticosteroids and atopy. Only categories with increase CA<sub>NO </sub>were related to poor asthma control and morbidity independent of baseline spirometry, bronchodilator response, atopic status, or use of inhaled corticosteroids.</p

    Perceived threat predicts the neural sequelae of combat stress

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    Exposure to severe stressors increases the risk for psychiatric disorders in vulnerable individuals, but can lead to positive outcomes for others. However, it remains unknown how severe stress affects neural functioning in humans and what factors mediate individual differences in the neural sequelae of stress. The amygdala is a key brain region involved in threat detection and fear regulation, and previous animal studies have suggested that stress sensitizes amygdala responsivity and reduces its regulation by the prefrontal cortex. In this study, we used a prospective design to investigate the consequences of severe stress in soldiers before and after deployment to a combat zone. We found that combat stress increased amygdala and insula reactivity to biologically salient stimuli across the group of combat-exposed individuals. In contrast, its influence on amygdala coupling with the insula and dorsal anterior cingulate cortex was dependent on perceived threat, rather than actual exposure, suggesting that threat appraisal affects interoceptive awareness and amygdala regulation. Our results demonstrate that combat stress has sustained consequences on neural responsivity, and suggest a key role for the appraisal of threat on an amygdala-centered neural network in the aftermath of severe stress

    β-Actin and γ-Actin Are Each Dispensable for Auditory Hair Cell Development But Required for Stereocilia Maintenance

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    Hair cell stereocilia structure depends on actin filaments composed of cytoplasmic β-actin and γ-actin isoforms. Mutations in either gene can lead to progressive hearing loss in humans. Since β-actin and γ-actin isoforms are 99% identical at the protein level, it is unclear whether each isoform has distinct cellular roles. Here, we compared the functions of β-actin and γ-actin in stereocilia formation and maintenance by generating mice conditionally knocked out for Actb or Actg1 in hair cells. We found that, although cytoplasmic actin is necessary, neither β-actin nor γ-actin is required for normal stereocilia development or auditory function in young animals. However, aging mice with β-actin– or γ-actin–deficient hair cells develop different patterns of progressive hearing loss and distinct pathogenic changes in stereocilia morphology, despite colocalization of the actin isoforms. These results demonstrate overlapping developmental roles but unique post-developmental functions for β-actin and γ-actin in maintaining hair cell stereocilia

    Factors associated with use of breast cancer screening services by women aged ≥ 40 years in Korea: The Third Korea National Health and Nutrition Examination Survey 2005 (KNHANES III)

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    <p>Abstract</p> <p>Background</p> <p>Despite evidence that breast cancer screening reduces morbidity and mortality, until recently most women have not undergone regular mammogram examinations in Korea. We aimed to identify factors associated with use of breast cancer screening services.</p> <p>Methods</p> <p>The Health Promotion Knowledge, Attitude and Practice survey (HP-KAP survey) is part of the Third Korea National Health and Nutrition Examination Survey 2005 (KNHANES III), a nationwide health survey in Korea. Of 7,802 individuals who participated in the HP-KAP survey, 4,292 were female. Of these, 2,583 were women aged at least 40 years and without a history of breast cancer; these women were included in this study. Information about breast cancer screening participation was obtained from the responses to questionnaires. The overall rate of regular breast cancer screening was measured. Factors that affect participation in a breast cancer screening program were identified using multiple logistic regression analysis.</p> <p>Results</p> <p>Among women aged at least 40 years, 30.4% complied with breast screening recommendations. Age of at least 65 years (adjusted odds ratio, aOR 0.61, 95% CI: 0.42-0.88), education level (no [ref], elementary school [aOR 1.51, 95% CI: 1.06-1.47], middle/high school [aOR 1.99, 95% CI: 1.36-2.92], university/higher [aOR 2.73, 95% CI: 1.71-4.35]), private health insurance (aOR 1.42, 95% CI: 1.71-4.35), attitude towards screening tests (aOR 0.18, 95% CI: 0.14-0.23), self-reported health status of 'fair' (aOR 1.26 95% CI: 1.00-1.58), and smoking (aOR 0.52, 95% CI: 0.35-0.79) were associated with the rate of regular breast cancer screening</p> <p>Conclusions</p> <p>To increase the nationwide breast cancer screening rate, more attention should be given to underrepresented groups, particularly the elderly, those with a low education level, smokers, and those with a negative attitude towards screening tests. These issues highlight the need for a new emphasis in health education, promotional campaigns and public health policy aimed at these underrepresented groups.</p
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