Search results for: H.P. van der Meulen

Items from 1 to 18 out of 18 results

article

Findings of a national comparative audit of mastectomy and breast reconstruction surgery in England

Ranjeet Jeevan, David A. Cromwell, John P. Browne, Christopher M. Caddy, more

Journal of Plastic, Reconstructive & Aesthetic Surgery > 2014 > 67 > 10 > 1333-1344

This paper summarises the findings of a national audit of mastectomy and breast reconstruction surgery carried out in England. It describes patterns of treatment, and the clinical and patient-reported quality of life outcomes associated with these types of procedure.Prospective cohort study.All 150 National Health Service hospital groups (NHS trusts) in England that provided mastectomy or breast reconstruction...

article

Temperature dependent single photon emission in InP/GaInP quantum dots

A.K. Nowak, E. Gallardo, D. Sarkar, D. Sanvitto, more

Physica E: Low-dimensional Systems and Nanostructures > 2010 > 42 > 10 > 2509-2513

Intensity correlation measurements on single InP/GaInP quantum dots (QDs) show antibunching at zero delay time, indicative of single photon emission. The antibunching time τ _R increases or decreases with temperature depending on the QD size as a result of the competition between: (1) thermal excitation of holes dominant in smaller QDs and (2) dark-to-bright exciton transition dominant in larger...

article

Trends in adult heart transplantation: a national survey from the United Kingdom Cardiothoracic Transplant Audit 1995–2007

Joyce Thekkudan, Chris A. Rogers, Helen L. Thomas, Jan H.P. van der Meulen, more

European Journal of Cardio-Thoracic Surgery > 2010 > 37 > 1 > 80-86

Objective: The management of heart failure (HF), peri-transplant care and immunosuppression has changed in the last decade. Here we describe the changes that have occurred in the UK national programme of adult heart transplantation (HTx). Methods: Using the data accrued with the UK Cardiothoracic Transplant Audit we undertook a prospective cohort study of 2958 consecutive adult patients listed for...

article

Resonant optical excitation and intermixing in InAs/AlAs single quantum dots

D. Sarkar, J.M. Calleja, H.P. van der Meulen, J.M. Meyer, more

Physica E: Low-dimensional Systems and Nanostructures > 2008 > 40 > 6 > 2172-2175

The optical excitation spectra of single self-organized InAs/AlAs quantum dots reveal transitions to excited states involving quantum dot phonons. Resonant excitation is observed at 31 and 41meV, corresponding to the “InAs-like” and “AlAs-like” optical phonons of InAlAs with low Al concentration. Polarization-resolved measurements reveal separate resonances at the fine structure split exciton levels...

article

Optical emission of InAs/GaAs quantum rings coupled to a two-dimensional photonic crystal microcavity

D. Sarkar, L.J. Martínez, I. Prieto-González, H.P. van der Meulen, more

Physica E: Low-dimensional Systems and Nanostructures > 2008 > 40 > 6 > 2156-2159

Microphotoluminescence measurements on InAs/GaAs quantum rings embedded in a bi-dimensional photonic crystal cavity display enhanced emission intensity of single rings depending on the coupling strength to the cavity modes. The cavity is formed by three holes missing at the center of the photonic crystal structure (a linear 3 defect, L3). Light emission by the quantum rings show sharp lines at low...

article

Continuous monitoring tools for pediatric surgical outcomes: an example using biliary atresia

Nokuthaba Sibanda, James D. Lewsey, Jan H.P. van der Meulen, Mark D. Stringer

Journal of Pediatric Surgery > 2007 > 42 > 11 > 1919-1925

Continuous monitoring tools can be used to monitor surgical outcomes over time. We illustrate the use of CUmulative SUM (CUSUM) charts in monitoring outcomes of Kasai portoenterostomy for treatment of biliary atresia at a supraregional unit.Data on 57 consecutive infants who underwent a Kasai portoenterostomy performed by a single surgeon between June 1994 and June 2006 were collected. A procedure...

article

Fine structure splitting and biexciton binding energy in single self-assembled InAs/AlAs quantum dots

D. Sarkar, H.P. van der Meulen, J.M. Calleja, J.M. Becker, more

Physica E: Low-dimensional Systems and Nanostructures > 2006 > 32 > 1-2 > 111-114

We report on photoluminescence investigations of individual InAs quantum dots embedded in an AlAs matrix which emit in the visible region, in contrast to the more traditional InAs/GaAs system. Biexciton binding energies, considerably larger than for InAs/GaAs dots, up to 9meV are observed. The biexciton binding energy decreases with decreasing dot size, reflecting a possible crossover to an antibinding...

article

An analysis of the Research Fellowship Scheme of the Royal College of Surgeons of England

Martin C. Nuttall, Jan H.P. van der Meulen, John P. Browne, Mark Emberton, more

Journal of the American College of Surgeons > 2005 > 200 > 2 > 186-190

The Research Fellowship Scheme of the Royal College of Surgeons of England commenced in 1993 with the aim of exposing selected surgical trainees to research techniques and methodology, with the hope of having an impact on surgical research and increasing the cadre of young surgeons who might decide to pursue an academic career in surgery. Over £11 million (approximately $20 million) has been invested...

article

Magneto-luminescence and magneto-transport of a two-dimensional electron gas around integer filling factors

H.P. van der Meulen, J.M. Calleja, J. Sanchez, R. Hey, more

Physica B: Physics of Condensed Matter > 2002 > 319 > 1-4 > 339-342

The magneto-optical emission of a high-mobility electron gas in a GaAs/AlGaAs single heterostructure shows a remarkable behavior near even filling factors in the quantum Hall regime. At low temperatures the light emission starts abruptly at filling factors ν=2, 4, 6, and is only observed in the presence of spin-down electrons in the last occupied Landau level (LL). For increasing magnetic field below...

article

Capture and confinement of light and carriers in graded-index quantum well laser structures

G. Aichmayr, H.P. van der Meulen, L. Viña, M. Calleja, more

Physica E: Low-dimensional Systems and Nanostructures > 2002 > 13 > 2-4 > 885-887

We investigated graded-index separate-confinement heterostructure lasers and compared their performance with a conventional quantum well laser by using Raman and time-resolved photoluminescence spectroscopy. We found that grading the index of the Ga ₁ _- _x Al _x As/GaAs waveguide and increasing the Al content improves considerably both, the light and carrier trapping and reduces...

article

Anomalous magneto-optical properties of a two-dimensional electron gas around integer filling factors

H.P. van der Meulen, J.M. Calleja, J. Sanchez, R. Hey, more

Physica E: Low-dimensional Systems and Nanostructures > 2002 > 12 > 1-4 > 535-538

Light emission from the lowest Landau level of a GaAs/AlGaAs single hetero-structure, in the integer quantum Hall regime, is observed only in the presence of spin-down electrons in the last occupied Landau level. At low temperatures the light emission starts abruptly at filling factors ν=2,4,6. For increasing magnetic field the emission energy remains essentially constant up to a critical field. Beyond...

article

Effects of prenatal exposure to the Dutch famine on adult disease in later life: an overview

Tessa J. Roseboom, Jan H.P. van der Meulen, Anita C.J. Ravelli, Clive Osmond, more

Molecular and Cellular Endocrinology > 2001 > 185 > 1-2 > 93 - 98

Chronic diseases are the main public health problem in Western countries. There are indications that these diseases originate in the womb. It is thought that undernutrition of the fetus during critical periods of development would lead to adaptations in the structure and physiology of the fetal body, and thereby increase the risk of diseases in later life. The Dutch famine-though a historical disaster-provides...

article

New results on the magneto-luminescence of a two-dimensional electron gas around integer filling factors

J.M. Calleja, H.P. van der Meulen, J. Sanchez, R. Hey, more

Solid State Communications > 2001 > 119 > 4-5 > 191-198

The magneto-photoluminescence emission of a high mobility electron gas in a GaAs/GaAlAs single hetero-structure shows a remarkable behavior near filling factor 2. The emission of the electron gas starts abruptly at ν=2 in a field range narrower than 1mT and shows a hysteresis cycle of 25–30mT. At low temperatures the emission energy remains essentially field-independent below ν=2 up to a critical...

article

Magnetic field dependence of many-body processes in quantum well luminescence

H.P. van der Meulen, J. Rubio, J.M. Calleja, H. Schweizer, more

Surface Science > 1996 > 361-362 > Complete > 372-375

The effect of electron-electron interactions on the optical properties of a two-dimensional electron gas under magnetic fields is studied in a modulation-doped single quantum well of InGaAs. Optical singularities at the Fermi level and shake-up side-bands are observed at low temperatures. Their intensities and lineshapes undergo drastic changes which are periodic in the filling factor. The results...

article

Phonon raman scattering in quantum wires

J. Rubio, H.P. Van der Meulen, N. Mestres, J. M. Calleja, more

Solid State Electronics > 1996 > 40 > 1-8 > 707-710

Phonons in narrow quantum wires of In ₀ _. ₅ ₃ Ga ₀ _. ₄ ₇ As showing strong one-dimensional confinement of carriers have been studied by Raman spectroscopy. A strong enhancement of the Raman intensity of the longitudinal optical phonon of the wires is observed for wire widths decreasing down to 40 nm. For narrower wires (10-30 nm), the Raman intensity falls...

article

Peak effect in the magnetostriction of superconducting NbTi due to elastic constants

U. Wyder, P.J.E.M. van der Linden, H.P. van der Meulen, A. Gerber, more

Physica B: Physics of Condensed Matter > 1995 > 211 > 1-4 > 265-268

The magnetostriction on polycrystalline superconducting NbTi perpendicular to the field is measured to study lattice deformation effects caused by fluxoids exerting forces on the lattice through pinning centers. A dip for increasing and a peak for decreasing fields in its length at 80% of the upper critical field (B _c ₂ = 12 T) was observed. Its temperature dependence is well...

article

Specific heat of PbMo ₆ S ₈ in high magnetic field

H.P. van der Meulen, J.A.A.J. Perenboom, T.T.J.M. Berendschot, J. Cors, more

Physica B: Physics of Condensed Matter > 1995 > 211 > 1-4 > 269-271

In order to investigate the volume upper critical field of the Chevrel-phase superconductor PbMo ₆ S ₈ , specific-heat measurements have been performed in magnetic fields up to 24.5 T. The superconducting transition temperature T _c of 14.3 (± 0.1) K is suppressed by the maximum magnetic field to 10.1 (± 0.3) K, which extrapolates to an upper critical field of 56 T (confirming...

article

High field dilatation experiments on U(Pt ₀ _. ₉ ₅ Pd ₀ _. ₀ ₅ ) ₃ ; Magnetic ordering versus heavy fermion behaviour

U. Wyder, H.P. van der Meulen, P.J.E.M. van der Linden, U. Zeitler, more

Physica B: Physics of Condensed Matter > 1995 > 206-207 > 437-440

A still open question is whether long-range magnetic ordering as observed in some heavy fermion (HF) systems is intimately related to the HF state or is an extra phenomenon interacting with it. This problem might be addressed by studying the compound U(Pt ₀ _. ₉ ₅ Pd ₀ _. ₀ ₅ ) ₃ . Doping UPt ₃ with 5% Pd induces long range antiferromagnetic...

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Keywords

PHOTOLUMINESCENCE (5)
HETEROJUNCTION (2)
INTEGER QUANTUM HALL EFFECT (2)
TWO-DIMENSIONAL ELECTRON GAS (2)
[PHYSICAL ASTRONOMY CLASSIFICATION SCHEME] 73.43.LP (2)
[PHYSICAL ASTRONOMY CLASSIFICATION SCHEME] 78.67.-N (2)
A. HETEROJUNCTIONS (1)
A. SEMICONDUCTORS (1)
BIEXCITONS (1)
BREAST CANCER (1)
BREAST RECONSTRUCTION (1)
CARRIER CAPTURE (1)
CORONARY HEART DISEASE (1)
D. QUANTUM HALL EFFECT (1)
DARK EXCITON (1)
E. LUMINESCENCE (1)
ENGLAND (1)
FETAL ORIGINS (1)
HEART FAILURE (1)
HEART TRANSPLANTATION (1)
III–V SEMICONDUCTORS (1)
MAGNETIC MEASUREMENTS (1)
MASTECTOMY (1)
OUTCOMES (1)
PHONONS (1)
PHOTON EMISSION (1)
PHOTONIC CRYSTAL MICROCAVITY (1)
QUALITY OF LIFE (1)
QUANTUM DOT (1)
QUANTUM DOTS (1)
QUANTUM RINGS (1)
QUANTUM WELL LASERS (1)
QUANTUM WELLS (1)
SINGLE PHOTON EMITTER (1)
SINGLE QUANTUM DOTS (1)
TIME-RESOLVED SPECTROSCOPY (1)
UNDERNUTRITION (1)
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Search results for: H.P. van der Meulen

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