863 research outputs found

    Printed analogue filter structures

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    The authors report progress in conductive lithographic film (CLF) technology, which uses the offset lithographic printing process to form electrically conductive patterns on flexible substrates. Networks of planar passive components and interconnects fabricated simultaneously via the CLF process form notch filter networks at 85 kHz

    RF circulator structures via offset lithography

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    Further developments are reported of the conductive lithographic film (CLF) process in which components of radio-frequency circulators are fabricated economically via offset lithography. The performance of centre conductor elements printed from silver-loaded inks on polymer substrates is compared with that of conventional solid copper structures

    Primordial black holes in braneworld cosmologies: Formation, cosmological evolution and evaporation

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    We consider the population evolution and evaporation of primordial black holes in the simplest braneworld cosmology, Randall-Sundrum type II. We demonstrate that black holes forming during the high-energy phase of this theory (where the expansion rate is proportional to the density) have a modified evaporation law, resulting in a longer lifetime and lower temperature at evaporation, while those forming in the standard regime behave essentially as in the standard cosmology. For sufficiently large values of the AdS radius, the high-energy regime can be the one relevant for primordial black holes evaporating at key epochs such as nucleosynthesis and the present. We examine the formation epochs of such black holes, and delimit the parameter regimes where the standard scenario is significantly modified.Comment: 9 pages RevTeX4 file with four figures incorporated, minor changes to match published versio

    Treatment related morbidity in differentiated thyroid cancer-a survey of clinicians.

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    Background: Differentiated thyroid cancer (DTC) has excellent long term survival in most patients. Long-term treatment related morbidity is therefore important, but may not be well characterised. The aim of this study was to conduct an electronic survey of clinicians involved in the care of patients with DTC to determine their views on treatment related morbidity. Methods: A nine item questionnaire was developed, piloted locally and sent by email to members of three United Kingdom (UK) medical organisations (Thyroid Cancer Forum, British Association of Endocrine and Thyroid Surgeons, British Thyroid Association). Results: 125 responses were received. Less than 5% of respondents had a formal protocol to detect morbidity associated with TSH suppression. Over 50% agreed that morbidity from TSH suppression is not well defined. The majority of responders also agreed that the long-term morbidity of hypocalcaemia, significant voice change and TSH suppression in DTC are not well characterised. Physicians perceived treatment related morbidity to be a bigger problem than surgeons (P = 0.019). Conclusion: Clinicians treating thyroid cancer agree that long-term treatment related morbidity from DTC is not well characterised. A study of the prevalence and severity of treatment related morbidity and its impact on health of patients with DTC is warranted

    Simulations of the Static Friction Due to Adsorbed Molecules

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    The static friction between crystalline surfaces separated by a molecularly thin layer of adsorbed molecules is calculated using molecular dynamics simulations. These molecules naturally lead to a finite static friction that is consistent with macroscopic friction laws. Crystalline alignment, sliding direction, and the number of adsorbed molecules are not controlled in most experiments and are shown to have little effect on the friction. Temperature, molecular geometry and interaction potentials can have larger effects on friction. The observed trends in friction can be understood in terms of a simple hard sphere model.Comment: 13 pages, 13 figure

    Solar Flares and Coronal Mass Ejections: A Statistically Determined Flare Flux-CME Mass Correlation

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    In an effort to examine the relationship between flare flux and corresponding CME mass, we temporally and spatially correlate all X-ray flares and CMEs in the LASCO and GOES archives from 1996 to 2006. We cross-reference 6,733 CMEs having well-measured masses against 12,050 X-ray flares having position information as determined from their optical counterparts. For a given flare, we search in time for CMEs which occur 10-80 minutes afterward, and we further require the flare and CME to occur within +/-45 degrees in position angle on the solar disk. There are 826 CME/flare pairs which fit these criteria. Comparing the flare fluxes with CME masses of these paired events, we find CME mass increases with flare flux, following an approximately log-linear, broken relationship: in the limit of lower flare fluxes, log(CME mass)~0.68*log(flare flux), and in the limit of higher flare fluxes, log(CME mass)~0.33*log(flare flux). We show that this broken power-law, and in particular the flatter slope at higher flare fluxes, may be due to an observational bias against CMEs associated with the most energetic flares: halo CMEs. Correcting for this bias yields a single power-law relationship of the form log(CME mass)~0.70*log(flare flux). This function describes the relationship between CME mass and flare flux over at least 3 dex in flare flux, from ~10^-7 to 10^-4 W m^-2.Comment: 28 pages, 16 figures, accepted to Solar Physic

    Large-scale Bright Fronts in the Solar Corona: A Review of "EIT waves"

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    ``EIT waves" are large-scale coronal bright fronts (CBFs) that were first observed in 195 \AA\ images obtained using the Extreme-ultraviolet Imaging Telescope (EIT) onboard the \emph{Solar and Heliospheric Observatory (SOHO)}. Commonly called ``EIT waves", CBFs typically appear as diffuse fronts that propagate pseudo-radially across the solar disk at velocities of 100--700 km s−1^{-1} with front widths of 50-100 Mm. As their speed is greater than the quiet coronal sound speed (cs≤c_s\leq200 km s−1^{-1}) and comparable to the local Alfv\'{e}n speed (vA≤v_A\leq1000 km s−1^{-1}), they were initially interpreted as fast-mode magnetoacoustic waves (vf=(cs2+vA2)1/2v_{f}=(c_s^2 + v_A^2)^{1/2}). Their propagation is now known to be modified by regions where the magnetosonic sound speed varies, such as active regions and coronal holes, but there is also evidence for stationary CBFs at coronal hole boundaries. The latter has led to the suggestion that they may be a manifestation of a processes such as Joule heating or magnetic reconnection, rather than a wave-related phenomena. While the general morphological and kinematic properties of CBFs and their association with coronal mass ejections have now been well described, there are many questions regarding their excitation and propagation. In particular, the theoretical interpretation of these enigmatic events as magnetohydrodynamic waves or due to changes in magnetic topology remains the topic of much debate.Comment: 34 pages, 19 figure
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