Over the last 25 years, radiowave detection of neutrino-generated signals, using cold polar ice as the neutrino target, has emerged as perhaps the most promising technique for detection of extragalactic ultra-high energy neutrinos (corresponding to neutrino energies in excess of 0.01 Joules, or 1017 electron volts). During the summer of 2021 and in tandem with the initial deployment of the Radio Neutrino Observatory in Greenland (RNO-G), we conducted radioglaciological measurements at Summit Station, Greenland to refine our understanding of the ice target. We report the result of one such measurement, the radio-frequency electric field attenuation length $L_\alpha$. We find an approximately linear dependence of $L_\alpha$ on frequency with the best fit of the average field attenuation for the upper 1500 m of ice: $\langle L_\alpha \rangle = ( ( 1154 \pm 121) - ( 0.81 \pm 0.14) \, ( \nu /{\rm MHz}) ) \,{\rm m}$ for frequencies ν ∈ [145 − 350] MHz.

Background:The Neurosurgical Atlas is a neurosurgical website with informative chapters and videos to promote excellence and safety in neurosurgical techniques. Here, we present our analysis of this website’s viewing data and describe how online neurosurgical resources are being utilized. We hope this will be a useful guide for neurosurgeons interested in online multimedia education. Methods: We analyzed Google Analytics data from The Neurosurgical Atlas between June 2016 and August 2017 which tracked user demographics, geographical location, and the videos watched. Views were also analyzed categorically by dividing videos into six neurosurgical topics and into basic and advanced levels as per their surgical complexity. Results: There were 246,259 website visits and 143,868 video plays. The most frequent age groups were 25-34 (44%) and 35-44 (24%). 71% of visitors were male. Most visitors were from the US (29.52%) and Brazil (6.43%). Website visits and video plays increased over time, with multiple peaks corresponding to promotional email updates. The six neurosurgical topics were all similarly popular. Conclusions: Our study presents the first piece of evidence demonstrating the feasibility and popularity of a free online resource in neurosurgical education. Our experience highlights the growing demand for free-access online chapters, anatomical illustrations, and operative videos.

Over the last decades, it has been progressively acknowledged that reducing the specific fuel consumption and the emission of pollutants, as well as improving the thrust-to-weight ratio involves extensive research on advanced sealing technologies. Amongst these, brush seals are particularly well considered for their excellent leakage performance, their low friction properties, and their ability to cope with inevitable rotor excursions during flights. This paper presents the experimental work that has been carried on in order to characterise carbon fibre brush seals leakage rate in function of the bristle pack geometry, under different pressure loads and rotational speeds. The analysed parameters are the bristle-free length, the density and the inter-plate distance. The work, performed by the ULB (Université Libre de Bruxelles) in collaboration with French engine manufacturer Safran Aircraft Engines, highlights specific behaviour of carbon fibre brush seals under differential pressure, proposes a leakage prediction model developed through empirical equations, and discusses over the most influential parameters that influence the air consumption of a brush seal.

Promastigotes of Leishmania braziliensis panamensis absorbed the purines adenine, hypoxanthine, adenosine and inosine by a combination of diffusion and mediated components. When the uptake rates for these substrates were corrected for diffusion and compared, the purine bases adenine and hypoxanthine were transported at a significantly slower rate than the purine nucleosides adenosine and inosine. Competitive interactions among those purines tested confirmed the presence of mediated and diffusion components and suggested that three transport loci may be operating (Fig. 6). The first transport locus, designated Locus 1, transported inosine, Locus 2, the purine bases hypoxanthine and adenine and Locus 3, adenosine. In addition, adenine and hypoxanthine inhibited the uptake of one another competitively. A comparison of Ki values derived from double reciprocal plots of labelled hypoxanthine and adenine uptake in the presence of the unlabelled substrates as inhibitors suggested that adenine has a greater affinity for the transport locus.

Rapid progress in photorefractive polymers includes new materials with improved response rates. We briefly review recent developments in this rapidly evolving area and report grating formation with a 2-millisecond time-constant, the fastest reported to date in any photorefractive polymer.

We discuss experiments and theory directed towards the development of a buckytube cold field emitter array electron cathode.

High quality lanthanum doped PZT films were deposited on platinum coated silicon wafers by direct liquid injection MOCVD using lead bis-tetramethylheptadione, lanthanum tri-tetramethylheptadione, zirconium tetramethylheptadione, and titanium ethoxide as precursors. The films were deposited at 650°C and a reduced pressure of 5 Torr. The deposition rates were higher than 10 nm/min. The liquid delivery system led to highly reproducible deposition rate, composition, and ferroelectric properties in the PLZT films. The remanent polarization of the films decreased from about 25 μC/cm2 for PLZT(0/55/45) to about 12 μC/cm2 for PLZT(8/55/45). The coercive field of the films seemed to be independent on the La doping concentration up to 8% La doping.

Buckytubes are considered for high current density cold field emitter array electron sources. They may provide more stable, higher-brightness emission than existing cold field emitter arrays.

Using hot-walled metallorganic chemical vapor deposition (MOCVD), thin fihns of lead zirconate titanate (PZT), lead titanate (PbTiO3 or PT) and bismuth titanate (Bi4Ti3O12 or BiT) were successfully prepared. For each material, titanium ethoxide (Ti(C2H5O)4) was used as the precursor for the titanium source, while lead bis-tetramethylheptadione (Pb(thd)2), zirconium tetrakistetramethylheptadione (Zr(thd)4) and triphenyl bismuth (Bi(C6H5)3) were used as sources for lead, zirconium and bismuth, respectively. Dense, specular and highly transparent films were obtained for all three materials. Deposition conditions are given for each of the materials as well as the properties of the resulting films as determined by XRD, SEM and UV-VIS-NIR spectrophotometry. Ferroelectric properties are also given for the PZT and BiT films; for PZT (%Zr = 41; %Ti = 9) annealed at 600 °C, the spontaneous polarization, Ps, was 23 μC/cm2 and the coercive field, Ec, was 65 kV/cm; for BiT annealed at 550 °C, the spontaneous polarization, Ps, was 27 μC/cm2 and the coercive field, Ec, was 240 kV/cm.

Transparent and highly specular PbTiO3 thin films were deposited on sapphire, platinum and ruthenium oxide-coated silicon wafers by hot-wall metallorganic chemical vapor deposition (MOCVD). Lead bis-tetramethylheptadionate and titanium ethoxide were used as chemical precursors. Films were deposited over a range of experimental conditions. X-ray diffraction (XRD) was used to determine the phases present in the films; Scanning Electron Microscopy (SEM) was used to examine the surface morphology and Energy Dispersive Spectroscopy (EDS) was used to determine the composition. Optical spectra were obtained to confirm the highly dense and transparent nature of the films. The chemical stability of the ruthenium oxide substrates in the MOCVD environment as well as the existence of a high-temperature deposition regime for composition control are also discussed.

Lead bis-tetramethylheptadionate (Pb(thd)2) is an extremely useful precursor for the preparation of lead-based thin films such as PZT, lead titanate, etc. In this paper, lead oxide was deposited from Pb(thd)2 in a hot-walled CVD reactor using oxygen as a reactive species and diluent gas. XRD and SEM were used to determine the structure of the material deposited by the CVD process. The CVD process consistently produced the monoxide of lead which was found to consist of a mixture of orthorhombic PbO with small tetragonal PbO platelets. TEM was used to determine the orientation of the individual platelets which was found to be consistently normal to the <201> family of zone axes. Deposition rates were determined and simulated using an FEM computer model to determine the rate constants for the overall deposition process.

The authors have developed two independent software packages that store x-ray peak locations, integrated intensities and full-width half-maximum intensity data as a function of diffractometer tilt and orientation angle; this information is used to compute residual stress tensor values. Each program retrieves the fitted x-ray peak locations from a dBASE-compatible data set that is independent of both x-ray diffractometer and acquisition software. Machine-specific routines have been coded to transfer peak data and general diffraction setup information from several different x-ray acquisition platforms into this common format. The two database management programs provide stand-alone storage, retrieval, analysis and graphic output of data, and thus have become practical laboratory vehicles toward establishing a standard database format for storing x-ray strain measurements and the residual stress values calculated therefrom.