276 research outputs found

    Tunable periodic microstrip structure on GaAs wafer

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    A one dimensional tunable periodic structure in microstip technology on gallium arsenide (GaAs) substrate is numerically investigated. The unit cell contains a number of patches positioned between the ground plane and the microstrip line. The patches, representing reactive loads, can be selectively short-circuited by externally-controlled FET switches integrated in the hosting substrate. The possibility of controlling the position of the band-gap, and implicitly the value of the e®ective dielectric constant along the line, for different combinations of the switches is demonstrate

    A Pulsed-air Model of Blue Whale B Call Vocalizations

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    Blue whale sound production has been thought to occur by Helmholtz resonance via air flowing from the lungs into the upper respiratory spaces. This implies that the frequency of blue whale vocalizations might be directly proportional to the size of their sound-producing organs. Here we present a sound production mechanism where the fundamental and overtone frequencies of blue whale B calls can be well modeled using a series of short-duration (\u3c1 \u3es) wavelets. We propose that the likely source of these wavelets are pneumatic pulses caused by opening and closing of respiratory valves during air recirculation between the lungs and laryngeal sac. This vocal production model is similar to those proposed for humpback whales, where valve open/closure and vocal fold oscillation is passively driven by airflow between the lungs and upper respiratory spaces, and implies call frequencies could be actively changed by the animal to center fundamental tones at different frequency bands during the call series

    Bloom-Gilman duality of inelastic structure functions in nucleon and nuclei

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    The Bloom-Gilman local duality of the inelastic structure function of the proton, the deuteron and light complex nuclei is investigated using available experimental data in the squared four-momentum transfer range from 0.3 to 5 (GeV/c)**2. The results of our analysis suggest that the onset of the Bloom-Gilman local duality is anticipated in complex nuclei with respect to the case of the protonand the deuteron. A possible interpretation of this result in terms of a rescaling effect is discussed with particular emphasis to the possibility of reproducing the damping of the nucleon-resonance transitions observed in recent electroproduction data off nuclei.Comment: revised version, to appear in Physical Review

    Validation of a new three-dimensional imaging system using comparative craniofacial anthropometry

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    Abstract Background The aim of this study is to validate a new three-dimensional craniofacial stereophotogrammetry imaging system (3dMDface) through comparison with manual facial surface anthropometry. The null hypothesis was that there is no difference between craniofacial measurements using anthropometry vs. the 3dMDface system. Methods Facial images using the new 3dMDface system were taken from six randomly selected subjects, sitting in natural head position, on six separate occasions each 1 week apart, repeated twice at each sitting. Exclusion criteria were excess facial hair, facial piercings and undergoing current dentofacial treatment. 3dMDvultus software allowed facial landmarks to be marked and measurements recorded. The same measurements were taken using manual anthropometry, using soluble eyeliner to pinpoint landmarks, and sliding and spreading callipers and measuring tape to measure distances. The setting for the investigation was a dental teaching hospital and regional (secondary and tertiary care) cleft centre. The main outcome measure was comparison of the craniofacial measurements using the two aforementioned techniques. Results The results showed good agreement between craniofacial measurements using the 3dMDface system compared with manual anthropometry. For all measurements, except chin height and labial fissure width, there was a greater variability with the manual method compared to 3D assessment. Overall, there was a significantly greater variability in manual compared with 3D assessments (p < 0.02). Conclusions The 3dMDface system is validated for craniofacial measurements

    Measurement of the Nucleon Structure Function F2 in the Nuclear Medium and Evaluation of its Moments

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    We report on the measurement of inclusive electron scattering off a carbon target performed with CLAS at Jefferson Laboratory. A combination of three different beam energies 1.161, 2.261 and 4.461 GeV allowed us to reach an invariant mass of the final-state hadronic system W~2.4 GeV with four-momentum transfers Q2 ranging from 0.2 to 5 GeV2. These data, together with previous measurements of the inclusive electron scattering off proton and deuteron, which cover a similar continuous two-dimensional region of Q2 and Bjorken variable x, permit the study of nuclear modifications of the nucleon structure. By using these, as well as other world data, we evaluated the F2 structure function and its moments. Using an OPE-based twist expansion, we studied the Q2-evolution of the moments, obtaining a separation of the leading-twist and the total higher-twist terms. The carbon-to-deuteron ratio of the leading-twist contributions to the F2 moments exhibits the well known EMC effect, compatible with that discovered previously in x-space. The total higher-twist term in the carbon nucleus appears, although with large systematic uncertainites, to be smaller with respect to the deuteron case for n<7, suggesting partial parton deconfinement in nuclear matter. We speculate that the spatial extension of the nucleon is changed when it is immersed in the nuclear medium.Comment: 37 pages, 15 figure

    Outcomes for paediatric Burkitt lymphoma treated with anthracycline-based therapy in Malawi

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    Burkitt lymphoma (BL) is the most common paediatric cancer in sub-Saharan Africa (SSA). Anthracyline-based treatment is standard in resource-rich settings, but has not been described in SSA. Children ≤ 18 years of age with newly diagnosed BL were prospectively enrolled from June 2013 to May 2015 in Malawi. Staging and supportive care were standardized, as was treatment with CHOP (cyclophosphamide, doxorubicin, vincristine, prednisone) for six cycles. Among 73 children with BL, median age was 9.2 years (interquartile range 7.7–11.8), 48 (66%) were male and two were positive for human immunodeficiency virus. Twelve (16%) had stage I/II disease, 36 (49%) stage III and 25 (34%) stage IV. Grade 3/4 neutropenia occurred in 17 (25%), and grade 3/4 anaemia in 29 (42%) of 69 evaluable children. Eighteen-month overall survival was 29% (95% confidence interval [CI] 18–41%) overall. Mortality was associated with age >9 years [hazard ratio [HR] 2.13, 95% CI 1.15–3.94], female gender (HR 2.12, 95% CI 1.12–4.03), stage (HR 1.52 per unit, 95% CI 1.07–2.17), lactate dehydrogenase (HR 1.03 per 100 iu/l, 95% CI 1.01–1.05), albumin (HR 0. 96 per g/l, 95% CI 0.93–0.99) and performance status (HR 0.78 per 10-point increase, 95% CI 0.69–0.89). CHOP did not improve outcomes in paediatric BL compared to less intensive regimens in Malawi

    Dolphin morbillivirus infection in different parts of the Mediterranean Sea

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    Morbillivirus were isolated from Mediterranean striped dolphins (Stenella coeruleoalba) dying along the coasts of Italy and Greece in 1991. They were antigenically identical to the morbilliviruses isolated from striped dolphins in Spain in 1990
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