A PCB-based electronic ELISA system for rapid, portable infectious disease diagnosis

In this paper an amperometric electrochemical detection method is demonstrated and implemented using exclusively Printed Circuit Board (PCB)-based technologies. A portable, reconfigurable, multichannel amperometric data-acquisition board has been designed and fabricated, dedicated to the measurement of current-input signals delivered by the PCB-based biosensor. The electronic read-out circuit is able to provide constant biasing voltages to the amperometric sensor, measure in real-time the sensor's output currents, digitise them using high-accuracy Analog-to-Digital Converters (ADCs) and send the binary data to the user either through a USB2.0 interface or via an on-board TFT touch-screen. In order to validate the robustness and accuracy of the combined system, proof-of-concept amperometric experiments have taken place using our custom-made PCB-based system and standard electrochemical substrates. The results obtained have been cross-validated by means of standard colorimetric analysis and their differences have been highlighted and analyzed

Binary Properties from Cepheid Radial Velocities (CRaV)

We have examined high accuracy radial velocities of Cepheids to determine the binary frequency. The data are largely from the CORAVEL spectrophotometer and the Moscow version, with a typical uncertainty of $\leq1$~km~s$^{-1}$, and a time span from 1 to 20 years. A systemic velocity was obtained by removing the pulsation component using a high order Fourier series. From this data we have developed a list of stars showing no orbital velocity larger than $\pm1$~km~s$^{-1}$. The binary fraction was analyzed as a function of magnitude, and yields an apparent decrease in this fraction for fainter stars. We interpret this as incompleteness at fainter magnitudes, and derive the preferred binary fraction of $29\pm8$\% ( $20\pm6$\% per decade of orbital period) from the brightest 40 stars. Comparison of this fraction in this period range (1-20 years) implies a large fraction for the full period range. This is reasonable in that the high accuracy velocities are sensitive to the longer periods and smaller orbital velocity amplitudes in the period range sampled here. Thus the Cepheid velocity sample provides a sensitive detection in the period range between short period spectroscopic binaries and resolved companions. The recent identification of $\delta$ Cep as a binary with very low amplitude and high eccentricity underscores the fact that the binary fractions we derive are lower limits, to which other low amplitude systems will probably be added. The mass ratio (q) distribution derived from ultraviolet observations of the secondary is consistent with a flat distribution for the applicable period range (1 to 20 years).Comment: accepted for publication in A

J-type Carbon Stars in the Large Magellanic Cloud

A sample of 1497 carbon stars in the Large Magellanic Cloud has been observed in the red part of the spectrum with the 2dF facility on the AAT. Of these, 156 have been identified as J-type (i.e. 13C-rich) carbon stars using a technique which provides a clear distinction between J stars and the normal N-type carbon stars that comprise the bulk of the sample, and yields few borderline cases. A simple 2-D classification of the spectra, based on their spectral slopes in different wavelength regions, has been constructed and found to be related to the more conventional c- and j-indices, modified to suit the spectral regions observed. Most of the J stars form a photometric sequence in the K - (J-K) colour magnitude diagram, parallel to and 0.6 mag fainter than the N star sequence. A subset of the J stars (about 13 per cent) are brighter than this J star sequence; most of these are spectroscopically different from the other J stars. The bright J stars have stronger CN bands than the other J stars and are found strongly concentrated in the central regions of the LMC. Most of the rather few stars in common with Hartwick and Cowley's sample of suspected CH stars are J stars. Overall, the proportion of carbon stars identified as J stars is somewhat lower than has been found in the Galaxy. The Na D lines are weaker in the LMC J stars than in either the Galactic J stars or the LMC N stars, and do not seem to depend on temperature.Comment: 19 pages, 21 figures, Latex; in press, MNRA

Disks in Expanding FRW Universes

We construct exact solutions to Einstein equations which represent relativistic disks immersed into an expanding FRW Universe. It is shown that the expansion influences dynamical characteristics of the disks such as rotational curves, surface mass density, etc. The effects of the expansion is exemplified with non-static generalizations of Kuzmin-Curzon and generalized Schwarzschild disks.Comment: Revised version to appear in ApJ, Latex, 17 pages, 10 figures, uses aaspp4 and epsf style file

The Lab-on-PCB framework for affordable, electronic-based point-of-care diagnostics: From design to manufacturing

A novel, Lab-on-Printed Circuit Board (LoPCB) manufacturing technology is demonstrated for the development of low-cost electrochemical biosensors combined with microfluidics for Point-of-Care (PoC) applications. An analysis of the developed PCB architecture is presented, detailing the three development areas of the proposed LoPCB platform, i.e. microfluidics, biosensors and electronics. Design rules and potential fabrication limitations are also discussed, based on the characterization of prototype fabricated systems. Two PCB-based devices have been designed and fabricated, a microfluidic active diluter with a variable and actively controlled dilution ratio and an electrochemical biosensor. The obtained results demonstrate the feasibility of a complete LoPCB platform, where all three compartments will co-exist and co-operate, providing an electronic-based PoC system for electrochemical biosensing

Discrete choice experiment exploring women's preferences in a novel device designed to monitor the womb environment and improve our understanding of reproductive disorders

Objectives: The study aims to determine the relative importance of key attributes of a novel intrauterine device. The device monitors uterine oxygen, pH and temperature in real time with the aim of improving our understanding and treatment of reproductive disorders. Design: A discrete choice experiment was used to elicit preferences in this novel investigative tool. The attributes and levels used in the choice scenarios were length of time using the device (7, 14 or 28 days), information obtained to guide treatment (limited, majority or all cases), risk of complications (1% or 10%) and discreteness (completely discrete, moderately discrete or indiscrete). Setting: Secondary care hospital in Hampshire, UK. Participants: 361 women of reproductive age. Primary and secondary outcome measures: Conditional logit and latent class logit regression models to determine the preference for each attribute. Results: Conditional logit coefficients allow comparison between attributes; women placed most importance on obtaining information to guide treatment in all cases (2.771), followed by having a completely discrete device (1.104), reducing risk of complications by 1% (0.184) and decreased length of time by 1 day (0.0150). All coefficients p<0.01. Latent class conditional logit assigns participants to two classes with 27.4% in class 1 who are less likely to have higher education or qualify for National Health Service-funded in vitro fertilisation compared with class 2. Those in class 2 placed 1.7 times more importance on a device whose information guided treatment in all cases and a 1% decrease in complications risk was nearly 15 times more attractive. Conclusions: Women placed most importance on having a device that obtains information to guide treatment and are willing to use the device for a longer, have a device with higher risk of complications and an indiscrete device if it is able to provide answers and direction for treatment of their reproductive disorder

Billiards in a general domain with random reflections

We study stochastic billiards on general tables: a particle moves according to its constant velocity inside some domain ${\mathcal D} \subset {\mathbb R}^d$ until it hits the boundary and bounces randomly inside according to some reflection law. We assume that the boundary of the domain is locally Lipschitz and almost everywhere continuously differentiable. The angle of the outgoing velocity with the inner normal vector has a specified, absolutely continuous density. We construct the discrete time and the continuous time processes recording the sequence of hitting points on the boundary and the pair location/velocity. We mainly focus on the case of bounded domains. Then, we prove exponential ergodicity of these two Markov processes, we study their invariant distribution and their normal (Gaussian) fluctuations. Of particular interest is the case of the cosine reflection law: the stationary distributions for the two processes are uniform in this case, the discrete time chain is reversible though the continuous time process is quasi-reversible. Also in this case, we give a natural construction of a chord "picked at random" in ${\mathcal D}$, and we study the angle of intersection of the process with a $(d-1)$-dimensional manifold contained in ${\mathcal D}$.Comment: 50 pages, 10 figures; To appear in: Archive for Rational Mechanics and Analysis; corrected Theorem 2.8 (induced chords in nonconvex subdomains

Automated registration of multimodal optic disc images: clinical assessment of alignment accuracy

Purpose: To determine the accuracy of automated alignment algorithms for the registration of optic disc images obtained by 2 different modalities: fundus photography and scanning laser tomography. Materials and Methods: Images obtained with the Heidelberg Retina Tomograph II and paired photographic optic disc images of 135 eyes were analyzed. Three state-of-the-art automated registration techniques Regional Mutual Information, rigid Feature Neighbourhood Mutual Information (FNMI), and nonrigid FNMI (NRFNMI) were used to align these image pairs. Alignment of each composite picture was assessed on a 5-point grading scale: “Fail” (no alignment of vessels with no vessel contact), “Weak” (vessels have slight contact), “Good” (vessels with 50% contact), and “Excellent” (complete alignment). Custom software generated an image mosaic in which the modalities were interleaved as a series of alternate 5×5-pixel blocks. These were graded independently by 3 clinically experienced observers. Results: A total of 810 image pairs were assessed. All 3 registration techniques achieved a score of “Good” or better in >95% of the image sets. NRFNMI had the highest percentage of “Excellent” (mean: 99.6%; range, 95.2% to 99.6%), followed by Regional Mutual Information (mean: 81.6%; range, 86.3% to 78.5%) and FNMI (mean: 73.1%; range, 85.2% to 54.4%). Conclusions: Automated registration of optic disc images by different modalities is a feasible option for clinical application. All 3 methods provided useful levels of alignment, but the NRFNMI technique consistently outperformed the others and is recommended as a practical approach to the automated registration of multimodal disc images

A sub-group of patients with hospital-acquired pneumonia do not require broad-spectrum gram-negative antimicrobial coverage

C.D.R. is supported by an Edinburgh Clinical Academic Track (ECAT)/Wellcome Trust PhD Training Fellowship for Clinicians award (214178/Z/18/Z).Among 200 patients developing hospital-acquired pneumonia (HAP) outside the intensive care unit, 61% were treated empirically without broad-spectrum Gram-negative coverage, with clinical cure in 69.7%. Lower disease severity markers (systemic inflammatory response syndrome, hypoxia, tachypnoea, neutrophilia) and the absence of diabetes mellitus and prior doxycycline treatment (but not the time to HAP onset) identified patients not requiring broad-spectrum Gram-negative coverage.Publisher PDFPeer reviewe

Can Solar Neutrinos be a Serious Background in Direct Dark Matter Searches?

The coherent contribution of all neutrons in neutrino nucleus scattering due to the neutral current is examined considering the boron solar neutrinos. These neutrinos could potentially become a source of background in the future dark matter searches aiming at nucleon cross sections in the region well below the few events per ton per year.Comment: 15 pages, 17 eps figure