Slow‐Wave Structures Utilizing Superconducting Thin‐Film Transmission Lines

Slow‐wave propagation of electromagnetic waves in transmission lines formed of thin‐film superconductors has been studied theoretically and experimentally. Previous theoretical analyses have been extended to include nonlocal theories. Strong dependence of phase velocity is found on film thickness and interfilm spacing when these become less than a few penetration depths. Velocity is also modified by coherence length, mean free path, nature of reflection of electrons at the film surfaces, and by temperature and magnetic field. Experimental measurements were made to verify the dependence on thickness, spacing, and temperature by means of a resonance technique. Agreement with theory was excellent in the case of temperature. Data taken for varying thickness and spacing verified the general trend of theoretical predictions. They indicate a nonlocal behavior with some specular reflection, but scatter of the data taken for different films prevents precise comparison of theory and experiment. Estimates of bulk penetration depths were made for indium, λ_In = 648±130 Å. For tantalum a rough estimate could be made of λTa = 580 Å. Data were consistent with the estimate of coherence length for indium of ξ_0 ≈ 3000 Å. Velocity was found to be independent of frequency in the range 50–500 MHz, while losses increased as the square. Pulse measurements indicated that delays of several microseconds and storage of several thousand pulses on a single line are feasible

Microlensing Detections of Moons of Exoplanets

We investigate the characteristic of microlensing signals of Earth-like moons orbiting ice-giant planets. From this, we find that non-negligible satellite signals occur when the planet-moon separation is similar to or greater than the Einstein radius of the planet. We find that the satellite signal does not diminish with the increase of the planet-moon separation beyond the Einstein radius of the planet unlike the planetary signal which vanishes when the planet is located well beyond the Einstein radius of the star. We also find that the satellite signal tends to have the same sign as that of the planetary signal. These tendencies are caused by the lensing effect of the star on the moon in addition to the effect of the planet. We determine the range of satellite separations where the microlensing technique is optimized for the detections of moons. By setting an upper limit as the angle-average of the projected Hill radius and a lower limit as the half of the Einstein radius of the planet, we find that the microlensing method would be sensitive to moons with projected separations from the planet of $0.05 {\rm AU} \lesssim d_{\rm p} \lesssim 0.24 {\rm AU}$ for a Jupiter-mass planet, $0.03 {\rm AU}\lesssim d_{\rm p} \lesssim 0.17 {\rm AU}$ for a Saturn-mass planet, and $0.01 {\rm AU} \lesssim d_{\rm p} \lesssim 0.08 {\rm AU}$ for a Uranus-mass planet. We compare the characteristics of the moons to be detected by the microlensing and transit techniquesComment: 6pages, 6 figure

Optical-Model Description of Time-Reversal Violation

A time-reversal-violating spin-correlation coefficient in the total cross section for polarized neutrons incident on a tensor rank-2 polarized target is calculated by assuming a time-reversal-noninvariant, parity-conserving ``five-fold" interaction in the neutron-nucleus optical potential. Results are presented for the system $n + {^{165}{\rm Ho}}$ for neutron incident energies covering the range 1--20 MeV. From existing experimental bounds, a strength of $2 \pm 10$ keV is deduced for the real and imaginary parts of the five-fold term, which implies an upper bound of order $10^{-4}$ on the relative $T$-odd strength when compared to the central real optical potential.Comment: 11 pages (Revtex

The Quantum Super Yangian and Casimir Operators of Uq(gl(M∣N))U_q(gl(M|N))

The quantum super Yangian $Y_q(gl(M|N))$ associated with the Perk - Schultz solution of the Yang - Baxter equation is introduced. Its structural properties are investigated, in particular, an extensive study of its central algebra is carried out. A $Z_2$ graded associative algebra epimorphism $Y_q(gl(M|N))--> U_q(gl(M|N))$ is established and constructed explicitly. Images of the central elements of the quantum super Yangian under this epimorphism yield the Casimir operators of the quantum supergroup $U_q(gl(M|N))$ constructed in an earlier publication.Comment: 10 pages in plain LaTe

Testing T Invariance in the Interaction of Slow Neutrons with Aligned Nuclei

The study of five-fold (P even, T odd) correlation in the interaction of slow polarized neutrons with aligned nuclei is a possible way of testing the time reversal invariance due to the expected enhancement of T violating effects in compound resonances. Possible nuclear targets are discussed which can be aligned both dynamically as well as by the "brute force" method at low temperature. A statistical estimation is performed of the five-fold correlation for low lying p wave compound resonances of the $^{121}$Sb, $^{123}$Sb and $^{127}$I nuclei. It is shown that a significant improvement can be achieved for the bound on the intensity of the fundamental parity conserving time violating (PCTV) interaction.Comment: 22 pages, 5 figures, published versio

IDEA intervention to prevent depressive symptoms and promote well-being in early-stage dementia: protocol for a randomised controlled feasibility study

OBJECTIVE: Depressive symptoms are common among people with dementia, impacting quality of life and cognitive and functional decline. Currently, little is known about the acceptability and feasibility of psychological interventions for people with mild dementia, with recent reviews identifying the need for further evidence. Developing and evaluating psychological interventions to prevent and treat these symptoms is, therefore, an important clinical and research priority. This protocol describes a study testing the acceptability and feasibility of a manual-based behavioural activation (BA) intervention for preventing and treating depressive symptoms in people with mild dementia. The aim of this study is to explore the feasibility of conducting a pragmatic multicentre randomised controlled trial of clinical effectiveness of an eight-session intervention. The Intervention to prevent Depressive symptoms and promote well-being in EArly-stage dementia (IDEA) programme supports people with dementia and their family carers in identifying and scheduling enjoyable and meaningful activities. METHODS AND ANALYSIS: Sixty people who have received a diagnosis of dementia of any type in the last 6 months will be recruited via memory clinics. Further criteria are a Mini-Mental State Examination score of ≥20, and a family carer who can assist with the intervention. Consenting participants will be randomised in a ratio of 2:1 to BA or to treatment as usual. Analyses will estimate parameters such as rates of recruitment, retention and number of sessions completed. Questionnaires measuring depressive symptoms and quality of life for both the person with dementia and their carer will be completed at baseline, 3 and 6 months. Qualitative interviews will explore acceptability of the intervention, study procedures and experiences of the sessions. ETHICS AND DISSEMINATION: This study received a favourable ethical opinion from the London Camberwell St Giles Research Ethics Committee (16/LO/0540). We will disseminate findings at key conferences, the Alzheimer’s Society and University College London websites and local stakeholder events. TRIAL REGISTRATION NUMBER: ISRCTN75503960; Pre-results

High Energy Neutrinos From Superheavy Dark Matter Annihilation

Superheavy ($M>10^{10}$ GeV) particles produced during inflation may be the dark matter, independent of their interaction strength. Strongly interacting superheavy particles will be captured by the sun, and their annihilation in the center of the sun will produce a flux of energetic neutrinos that should be detectable by neutrino telescopes. Depending on the particle mass, event rates in a cubic-kilometer detector range from several per hour to several per year. The signature of the process is a predominance of tau neutrinos, with a relatively flat energy spectrum of events ranging from 50 GeV to many TeV, and with the mean energy of detected tau neutrinos about 3 TeV.Comment: 24 pages, 7 figure

First-order phase transition in a 2D random-field Ising model with conflicting dynamics

The effects of locally random magnetic fields are considered in a nonequilibrium Ising model defined on a square lattice with nearest-neighbors interactions. In order to generate the random magnetic fields, we have considered random variables $\{h\}$ that change randomly with time according to a double-gaussian probability distribution, which consists of two single gaussian distributions, centered at $+h_{o}$ and $-h_{o}$, with the same width $\sigma$. This distribution is very general, and can recover in appropriate limits the bimodal distribution ($\sigma\to 0$) and the single gaussian one ($ho=0$). We performed Monte Carlo simulations in lattices with linear sizes in the range $L=32 - 512$. The system exhibits ferromagnetic and paramagnetic steady states. Our results suggest the occurence of first-order phase transitions between the above-mentioned phases at low temperatures and large random-field intensities $h_{o}$, for some small values of the width $\sigma$. By means of finite size scaling, we estimate the critical exponents in the low-field region, where we have continuous phase transitions. In addition, we show a sketch of the phase diagram of the model for some values of $\sigma$.Comment: 13 pages, 9 figures, accepted for publication in JSTA

Changing eruptive styles and textural features from phreatomagmatic to strombolian activity of basaltic littoral cones: Los Erales cinder cone, Tenerife, Canary Islands

Montaña Los Erales is a 70 m high Quaternary cinder cone in the Bandas del Sur region, south Tenerife. Field observations on excavated sections and SEM analysis of tephra samples from the cone suggest that the eruption style of this vent changed progressively from an initial hydrovolcanic phase, through a transitional stage, to one that was entirely strombolian. Clast sizes increase from ≤1 cm angular lapilli in hydrovolcanic samples to 15 cm bombs in strombolian samples. Vesicles also increase in size from 0.5 mm to 1.2 mm, becoming more rounded in the strombolian samples. Palagonitization, extensive in the hydrovolcanic deposits, becomes less noticeable in strombolian deposits. To investigate the causes for and the nature of these changes in eruptive style, products from each major unit were analysed for their morphology, using scanning electron microscopy with both SE and BSE imaging as tephra morphologies are known to reflect the eruptive regime and degree of explosivity at the time of eruption. SEM imaging of hydrovolcanic samples illustrate angular fragments that have been rapidly quenched and contain high levels of palagonitisation and zeolitisation, whereas strombolian samples appear to be less altered and display larger clast sizes and vesicles. Our results confirm that the initial phase of activity was largely driven by magma-water (coolant) interaction, where magma may have interacted with a lens of fresh ground or surface water, causing intense fragmentation of the magma. With proceeding eruptive activity the water became exhausted, giving rise to an entirely strombolian eruptive style. Additionally, fossil diatoms were found in hydrovolcanic samples, further emphasising the influence of a, probably fluvial, water source during the early phase of emplacement.La Montaña de Los Erales es un cono de cínder del Cuaternario de 70 m de altura situado en la zona de las Bandas del Sur, en el litoral meridional de la isla de Tenerife. Observaciones de campo en secciones excavadas en los flancos del cono y análisis SEM de las muestras de tefra sugieren que el estilo eruptivo de este aparato volcánico cambió progresivamente durante la erupción de una fase inicial hidrovolcánica a una final enteramente estromboliana, con estadios intermedios transicionales. El tamaño de los clastos aumenta de ≤1 cm de lapilli angular en las muestras hidrovolcánicas a bombas de 15 cm en las estrombolianas. Las vesículas también aumentan en tamaño desde 0,5 mm a 1,2 mm, volviéndose más redondeadas en las muestras estrombolianas. Los intensos procesos de palagonitización de los depósitos hidrovolcánicos son menos significativos en las fases estrombolianas. Con objeto de investigar la naturaleza y las causas de estos cambios se analizó la morfología de los productos de las principales fases. Se han utilizado para ello imágenes de microscopía electrónica (SE y BSE), ya que se sabe que las diferentes morfologías de estos piroclastos reflejan el régimen eruptivo y el grado de explosividad durante la erupción. Las imágenes SEM de las muestras hidrovolcánicas presentan fragmentos angulares que se han enfriado rápidamente y con elevado grado de palagonitización y zeolitización. Las estrombolianas, en cambio, aparecen menos alteradas y muestran mayor tamaño de clastos y vesículas. Los resultados obtenidos indican que la fase inicial de la erupción se caracteriza por una importante interacción magma-agua (refrigerante), probablemente relacionada con una cantidad limitada de agua superficial o freática que produjo la intensa fragmentación del magma. En el transcurso de la erupción la fuente de agua se agotó, dando lugar a las fases finales de carácter enteramente estromboliano. Fósiles de diatomeas, que se han encontrado asociados a las muestras hidrovolcánicas, refuerzan la posibilidad de que el agua fuera de origen superficial, probablemente el cauce de un barranco

Coronary artery aneurysm in Kawasaki disease.

A 3-year-old male presents to the emergency department with chief complaints of fever and vomiting. He had a positive rapid streptococcus throat test with cervical lymphadenopathy. The patient was started on antibiotics. On examination, there was diffuse erythematous macular rash on the chest. Laboratory tests revealed elevated white cell count and C-reactive protein. Electrocardiogram was notable for prolonged PR interval indicating 1st degree atrioventricular block. Echocardiogram revealed ectasia of the right coronary artery (RCA). A presumptive diagnosis of Kawasaki disease was made and the patient was started on high-dose aspirin and intravenous immunoglobulins. Cardiac computed tomography angiography (CTA) showed an aneurysm of the proximal RCA measuring up to 7.4 mm. The RCA immediately proximal to the aneurysm measured 3 mm in diameter. The Z score was 13.4. Oblique coronal image from cardiac CTA and volume rendered images demonstrated an aneurysm of the proximal RCA. The patient improved with treatment