2,936 research outputs found

    Generalized Bloch's theorem for viscous metamaterials: Dispersion and effective properties based on frequencies and wavenumbers that are simultaneously complex

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    It is common for dispersion curves of damped periodic materials to be based on real frequencies as a function of complex wavenumbers or, conversely, real wavenumbers as a function of complex frequencies. The former condition corresponds to harmonic wave motion where a driving frequency is prescribed and where attenuation due to dissipation takes place only in space alongside spatial attenuation due to Bragg scattering. The latter condition, on the other hand, relates to free wave motion admitting attenuation due to energy loss only in time while spatial attenuation due to Bragg scattering also takes place. Here, we develop an algorithm for 1D systems that provides dispersion curves for damped free wave motion based on frequencies and wavenumbers that are permitted to be simultaneously complex. This represents a generalized application of Bloch's theorem and produces a dispersion band structure that fully describes all attenuation mechanisms, in space and in time. The algorithm is applied to a viscously damped mass-in-mass metamaterial exhibiting local resonance. A frequency-dependent effective mass for this damped infinite chain is also obtained

    Quantifying tumour-infiltrating lymphocyte subsets : a practical immuno-histochemical method

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    Background: Efficient histological quantification of tumour-infiltrating T and B lymphocyte (TIL) subsets in archival tissues would greatly facilitate investigations of the role of TIL in human cancer biology. We sought to develop such a method. Methods: Ten ×40 digital images of 4 μ sections of 16 ductal invasive breast carcinomas immunostained for CD3, CD4, CD8, and CD20 were acquired (a total of 640 images). The number of pixels in each image matching a partition of Lab colour space corresponding to immunostained cells were counted using the ‘Color range’ and ‘Histogram’ tools in Adobe Photoshop 7. These pixel counts were converted to cell counts per mm2 using a calibration factor derived from one, two, three or all 10 images of each case/antibody combination. Results: Variations in the number of labelled pixels per immunostained cell made individual calibration for each case/antibody combination necessary. Calibration based on two fields containing the most labelled pixels gave a cell count minimally higher (+ 5.3%) than the count based on 10-field calibration, with 95% confidence limits − 14.7 to + 25.3%. As TIL density could vary up to 100-fold between cases, this accuracy and precision are acceptable. Conclusion: The methodology described offers sufficient accuracy, precision and efficiency to quantify the density of TIL sub-populations in breast cancer using commonly available software, and could be adapted to batch processing of image files

    Optimal Formation Design for Imaging and Fuel Usage

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77028/1/AIAA-20080-363.pd

    A combined digital linearization and channel estimation approach for IM/DD fast-OFDM systems

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    A combined digital linearization and channel estimation scheme is proposed and experimentally demonstrated for short-reach intensity-modulation and direct-detection (IM/DD) optical Fast-OFDM systems. Known 2PAM-Fast-OFDM sequences are used for training a memoryless polynomial based adaptive post-distorter and for FFT-based channel estimation in IM/DD 4PAM-Fast-OFDM systems. The 2PAM signals are transmitted only over the odd SCs of the training sequences. With the combined compensation scheme, significant BER improvements are achieved for 10- and 22-km length 12.5 Gbit/s SMF links. Compared with a conventional IM/DD Fast-OFDM, the receiver sensitivity of the proposed IM/DD Fast-OFDM system is improved by about 3 dB at a bit error ratio (BER) of 10–3, after 22-km SMF transmission. In addition, the experimental results for different bias voltages and under strong filtering effects show that the proposed compensation approach can deal with some degree of MZM bias drift and can be applied for realistic wideband optical Fast-OFDM systems

    Desertification

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    IPCC SPECIAL REPORT ON CLIMATE CHANGE AND LAND (SRCCL) Chapter 3: Climate Change and Land: An IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystem

    The use of behaviour management techniques amongst paediatric dentists working in the Arabian region: a cross‑sectional survey study

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    Purpose The purposes of this study were to investigate paediatric dental practitioners’ training and confidence in using dental behaviour management techniques in the Arabian region and to assess the factors influencing the application of advanced behaviour management techniques. Methods: An online questionnaire was distributed to paediatric dental practitioners in the Arabian region. Data were analysed using descriptive statistics and Pearson Chi Square. Results A total of 113 responses were obtained. Of these, the majority were from Egypt (45%, n = 51). Just over half of the respondents were registered as specialists at the country where they were practicing paediatric dentistry (53%, n = 60). The use of behaviour management techniques varied amongst participants with tell-show-do (95%, n = 107) and positive reinforcement (89%, n = 101) being the most routinely used techniques. The majority of participants reported using voice control (83%) and parental separation (68%) techniques. Hand over mouth exercise (HOME) was only used by 24% (n = 27) of participants, whilst just over half of the participants, 53%, reported using protective stabilisation. A significant association was shown between country of practice, country of obtaining paediatric dental training, speciality status and the use of advanced behaviour management techniques, whilst confidence in using HOME and sedation were associated with work setting and country of practice, respectively. Conclusion The use of advanced behaviour management techniques was found to be high amongst respondents in the Arabian region. The lack of training in using these techniques, however, is of concern. Further assessment of the factors affecting the use of and confidence in applying advanced behaviour management techniques in the Arabian region is needed

    Comment on ``Critical Behavior in Disordered Quantum Systems Modified by Broken Time--Reversal Symmetry''

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    In a recent Letter [Phys. Rev. Lett. 80, 1003 (1998)] Hussein and Pato employed the maximum entropy principle (MEP) in order to derive interpolating ensembles between any pair of universality classes in random matrix theory. They apply their formalism also to the transition from random matrix to Poisson statistics of spectra that is observed for the case of the Anderson-type metal-insulator transition. We point out the problems with the latter procedure.Comment: 1 page in PS, to appear in PRL Sept. 2

    The mean energy, strength and width of triple giant dipole resonances

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    We investigate the mean energy, strength and width of the triple giant dipole resonance using sum rules.Comment: 12 page

    Rotating ground states of trapped Bose atoms with arbitrary two-body interactions

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    In a k-dimensional system of weakly interacting Bose atoms trapped by a spherically symmetric and harmonic external potential, an exact expression is obtained for the rotating ground states at a fixed angular momentum. The result is valid for arbitrary interactions obeying minimal physical requirements. Depending on the sign of a modified scattering length, it reduces to either a collective rotation or a condensed vortex state, with no alternative. The ground state can undergo a kind of quantum phase transition when the shape of the interaction potential is smoothly varied.Comment: Talk given at the International Conference on Theoretical Physics (TH2002),Paris, UNESCO, 22-27 July; 11 pages, 3 figures, few typos fixe

    Evaluation of plasma neurotransmitters in children living with Attention-Deficit Hyperactivity Disorder (ADHD)

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    This study aimed to ascertain the underlying neuro-biochemical imbalances that exist in children with ADHD by assessing the plasma levels of dopamine, serotonin, norepinephrine, γ aminobutyric acid (GABA) and glutamate. Moreover, it investigated the potential effects of PUFA and vitamins supplementation as an alternative therapy to modulate the levels of these neurotransmitters and the overall clinical status of ADHD patients. The study included 40 ADHD patients, aged 4-6 years. The diagnostic and statistical manual of mental disorders (DSM-5) test has been employed to diagnose patients with ADHD and the severity of symptoms was assessed using the Arabic version of Conners' Parent Rating Scale. Additionally, patients were assessed using the Arabic versions of Mini International Neuropsychiatric Interview for Children (M.I.N.I. Kid) and Stanford-Binet Intelligence Scale, 5th Edition (SB5). Recruited patient received nutritional supplement of semi-solid diet containing 1000 mg PUFA with selected vitamins once daily for six months. The evaluation of ADHD symptoms and levels of neurotransmitters has been carried out at pre-/post-intervention stage. Post-nutrition intervention assessment, there was a significant increase in dopamine, norepinephrine, GABA levels (p-value < 0.0001) with significant decrease in glutamate level (p-value < 0.0001) when compared to their correspondent pre-intervention levels. Symptoms of inattention and/or hyperactivity-impulsivity were significantly improved after 6 months nutrition intervention program (p-value<0.001). Therefore, supplementation with omega-3 fatty acids and vitamins could be considered more extensively in therapy of ADHD patients particularly those who are less than 6 years old
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