Energy levels of a parabolically confined quantum dot in the presence of spin-orbit interaction

We present a theoretical study of the energy levels in a parabolically confined quantum dot in the presence of the Rashba spin-orbit interaction (SOI). The features of some low-lying states in various strengths of the SOI are examined at finite magnetic fields. The presence of a magnetic field enhances the possibility of the spin polarization and the SOI leads to different energy dependence on magnetic fields applied. Furthermore, in high magnetic fields, the spectra of low-lying states show basic features of Fock-Darwin levels as well as Landau levels.Comment: 6 pages, 4 figures, accepted by J. Appl. Phy

Medical students' comfort levels with performing the basic head and neck examination in practice: follow-up during the core clerkship year.

ObjectiveFollowing our preliminary study on junior medical students' comfort levels in performing the head and neck physical examination (H&NPE) before and after a department-led teaching session, we assessed the longitudinal effect of this session on students during the core clinical clerkship year, in which these skills were performed on real patients.DesignAnonymous cross-sectional survey study as a follow-up to previous intervention.MethodsOverall, 101 and 90 second-year medical students participated in an H&NPE teaching session 1 year before the current survey administration in 2 consecutive years. The same cohorts of students, as third years, were asked to rate their comfort levels (0-5-point Likert scale) in performing the H&NPE and the importance of otolaryngology rotations in medical school and primary care residency training.ResultsOf the 101 and 90 students, 53 and 46 medical students completed the follow-up survey in each respective year. For both classes, compared with before the teaching session, students reported an average comfort level of 2.8 (somewhat to moderately comfortable) in performing the complete H&NPE (p < 0.0001) during the core clinical clerkship year. Similar changes were observed for the individual ear, nose, mouth, and neck components of the examination (all p's < 0.0002). Students at follow-up reported statistically similar comfort levels when compared with immediately after the teaching session for the ear, oral cavity, and neck examinations.ConclusionThe initial teaching session persistently improved medical students' comfort levels in performing the H&NPE, with some attrition in comfort levels with performing the nasal examination and complete H&NPE. An otolaryngologist-directed, practical educational intervention may permanently reinforce the acquisition of complex skills such as the H&NPE

Effect of lubricant environment on saw damage in silicon wafers

The chemomechanical effect of lubricant environments on the inner diameter (ID) sawing induced surface damage in Si wafers was tested for four different lubricants: water, dielectric oil, and two commercial cutting solutions. The effects of applying different potential on Si crystals during the sawing were also tested. It is indicated that the number and depth of surface damage are sensitive to the chemical nature of the saw lubricant. It is determined that the lubricants that are good catalysts for breaking Si bonds can dampen the out of plane blade vibration more effectively and produce less surface damage. Correlations between the applied potential and the depth of damage in the dielectric oil and one of the commercial cutting solutions and possible mechanisms involved are discussed

Instrumentation of a high-sensitivity microwave vector detection system for low-temperature applications

We present the design and the circuit details of a high-sensitivity microwave vector detection system, which is aiming for studying the low-dimensional electron system embedded in the slots of a coplanar waveguide at low temperatures. The coplanar waveguide sample is placed inside a phase-locked loop; the phase change of the sample may cause a corresponding change in the operation frequency, which can be measured precisely. We also employ a double-pulse modulation on the microwave signals, which comprises a fast pulse modulation for gated averaging and a slow pulse modulation for lock-in detection. In measurements on real samples at low temperatures, this system provides much better resolutions in both amplitude and phase than most of the conventional vector analyzers at power levels below -65 dBm.Comment: 7 pages, 11 figures, 1 table, lette

Complete response of skull base inverted papilloma to chemotherapy: Case report.

BackgroundInverted papilloma (IP) is the most common benign sinonasal neoplasm. Endoscopic techniques, improved understanding of pathophysiology, and novel surgical approaches have allowed rhinologists to treat IPs more effectively, with surgery being the mainstay of therapy. Frontal sinus IP poses a challenge for surgical therapy due to complex anatomy and potentially difficult surgical access.ObjectivesWe reported a unique case of a massive frontal sinus IP that presented with intracranial and orbital extension, with near resolution after chemotherapy.MethodsA retrospective case review of a patient with a frontal sinus IP treated at a tertiary academic medical center.ResultsA 75-year-old male patient presented with nasal obstruction, purulent nasal discharge, and a growing left supraorbital mass. Endoscopy demonstrated a mass that filled both frontal and ethmoid sinuses, with orbital invasion. There also was substantial erosion of the posterior table, which measured 1.73 × 1.40 cm. A biopsy specimen demonstrated IP with carcinoma in situ. The patient was deemed unresectable on initial evaluation and, subsequently, underwent chemotherapy (carboplatin and paclitaxel). The tumor had a dramatic response to chemotherapy, and the patient elected for definitive surgery to remove any residual disease. During surgery, only a small focus of IP was found along the superior wall of the frontal sinus. No tumor was found elsewhere, including at the site of skull base erosion. The final pathology was IP without carcinoma in situ or dysplasia.ConclusionThis was the first reported case of chemotherapeutic "debulking" of IP, which facilitated surgical resection, despite substantial intracranial and orbital involvement. Although nearly all IPs can be treated surgically, rare cases, such as unresectable tumors, may benefit from systemic chemotherapy

Three-dimensional solutions for the geostrophic flow in the Earth's core

In his seminal work, Taylor (1963) argued that the geophysically relevant limit for dynamo action within the outer core is one of negligibly small inertia and viscosity in the magnetohydrodynamic equations. Within this limit, he showed the existence of a necessary condition, now well known as Taylor's constraint, which requires that the cylindrically-averaged Lorentz torque must everywhere vanish; magnetic fields that satisfy this condition are termed Taylor states. Taylor further showed that the requirement of this constraint being continuously satisfied through time prescribes the evolution of the geostrophic flow, the cylindrically-averaged azimuthal flow. We show that Taylor's original prescription for the geostrophic flow, as satisfying a given second order ordinary differential equation, is only valid for a small subset of Taylor states. An incomplete treatment of the boundary conditions renders his equation generally incorrect. Here, by taking proper account of the boundaries, we describe a generalisation of Taylor's method that enables correct evaluation of the instantaneous geostrophic flow for any 3D Taylor state. We present the first full-sphere examples of geostrophic flows driven by non-axisymmetric Taylor states. Although in axisymmetry the geostrophic flow admits a mild logarithmic singularity on the rotation axis, in the fully 3D case we show that this is absent and indeed the geostrophic flow appears to be everywhere regular.Comment: 29 Pages, 8 figure

Analytical Solution to Transport in Brownian Ratchets via Gambler's Ruin Model

We present an analogy between the classic Gambler's Ruin problem and the thermally-activated dynamics in periodic Brownian ratchets. By considering each periodic unit of the ratchet as a site chain, we calculated the transition probabilities and mean first passage time for transitions between energy minima of adjacent units. We consider the specific case of Brownian ratchets driven by Markov dichotomous noise. The explicit solution for the current is derived for any arbitrary temperature, and is verified numerically by Langevin simulations. The conditions for vanishing current and current reversal in the ratchet are obtained and discussed.Comment: 4 pages, 3 figure

Are the Stock Markets “Rigged”? An Empirical Analysis of Regulatory Change

Volatile events in the stock market such as the 2010 Flash Crash have sparked concern that financial markets are “rigged” in favor of trading firms that use high frequency trading (“HFT”) systems. We analyze a regulatory change implemented by the SEC in 2007 by examining its effect on a key market metric, the bid-ask spread, an investor cost, and find that the regulatory shift, indeed, disadvantages investors. We link the implementation of this change to a shift in the volume of trades from a low-cost venue to a high-cost venue. We argue that this outcome is predicted by the incentives of the venues, non-profit stock exchanges owned by different types of members. The lessvolatile, lower-cost New York Stock Exchange was owned by underwriters and included a specialist system that is less vulnerable to HFT tactics that can disadvantage investors

A Blueprint for Translational Regenerative Medicine

The last few decades have produced a large number of proof-of-concept studies in regenerative medicine. However, the route to clinical adoption is fraught with technical and translational obstacles that frequently consign promising academic solutions to the so-called “valley of death.” This review is intended to serve as a blueprint for translational regenerative medicine: we suggest principles to help guide cell and material selection, present key in vivo imaging modalities and argue that the host immune response should be considered throughout therapeutic development. Finally, we suggest a pathway to navigate the often complex regulatory and manufacturing landscape of translational regenerative medicine.J.P.K.A. acknowledges support from an Arthritis Research U.K. Foundation Fellowship (21138) and the Medical Research Council (MRC) (MR/S00551X/1). T.J.K. acknowledges the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie Individual European Fellowship (Grant Agreement No. 746980). A.C.R. acknowledges support from the Wellcome Trust Institutional Translational Partnership Award (208858/Z/17/Z). P.S.P. acknowledges funding from the UK Regenerative Medicine Platform (MR/K026739/1), the MRC (MR/R026416/1), and the EPSRC (EP/R511638/1). C.M.M. was supported by the MRC-funded UK Regenerative Medicine Platform Immunomodulation Hub award (MR/L022699/1). W.L.K. is supported by the MRC/UKRI Innovate Fellowship (MR/S005528/1). V.P. acknowledges funding from the UK Regenerative Medicine Platform (MR/R015724/1). R.O.C.O acknowledges support from the UK Regenerative Medicine Platform “Acellular / Smart Materials – 3D Architecture” (MR/R015651/1), the Rosetrees Trust, Wessex Medical Research and Biotechnology and Biological Sciences Research Council (BBSRC) (BB/P017711/1). D.J.S. acknowledges support from a British Heart Foundation (BHF) Intermediate Basic Science Research Fellowship (FS/15/33/31608), the BHF Centre for Regenerative Medicine (RM/17/1/33377), and an MRC Project Grant (MR/R026416/1). F.M.W. acknowledges support from the UK Regenerative Medicine Platform (MR/LO22699/1, MR/R015635/1, MR/K026666/1). S.J.F. acknowledges support from the UK Regenerative Medicine Platform Engineered Cell Environment Hub and the MRC. R.A.B. acknowledges MRC-WT funding of the Cambridge Stem Cell Institute and MRC funding of the UK Regenerative Medicine Platform Pluripotent Stem and Engineered Cell hub (MR/R015724/1) along with funding from the Rosetrees Trust (A1519 M654) and Cure Parkinson's Trust. R.A.B. is also supported by NIHR funding of Biomedical Research Centre Cambridge (146281). R.A.B. is an NIHR Senior Investigator (NF-SI-0616-10011) and a 23 P.I. in the MRC/WT Stem Cell Institute (203151/Z/16/Z). M.M.S. acknowledges support from the grant from the UK Regenerative Medicine Platform “Acellular / Smart Materials – 3D Architecture” (MR/R015651/1), the European Research Council (ERC) Seventh Framework Programme Consolidator grant “Naturale CG” (616417), the Rosetrees Trust and the Wellcome Trust Senior Investigator Award (098411/Z/12/Z). The authors would also like to thank David Pan (MRC) for his input into this manuscript during the course of Phases 1 and 2 of the UK Regenerative Medicine Platform