From white elephant to Nobel Prize: Dennis Gabor’s wavefront reconstruction

Dennis Gabor devised a new concept for optical imaging in 1947 that went by a variety of names over the following decade: holoscopy, wavefront reconstruction, interference microscopy, diffraction microscopy and Gaboroscopy. A well-connected and creative research engineer, Gabor worked actively to publicize and exploit his concept, but the scheme failed to capture the interest of many researchers. Gabor’s theory was repeatedly deemed unintuitive and baffling; the technique was appraised by his contemporaries to be of dubious practicality and, at best, constrained to a narrow branch of science. By the late 1950s, Gabor’s subject had been assessed by its handful of practitioners to be a white elephant. Nevertheless, the concept was later rehabilitated by the research of Emmett Leith and Juris Upatnieks at the University of Michigan, and Yury Denisyuk at the Vavilov Institute in Leningrad. What had been judged a failure was recast as a success: evaluations of Gabor’s work were transformed during the 1960s, when it was represented as the foundation on which to construct the new and distinctly different subject of holography, a re-evaluation that gained the Nobel Prize for Physics for Gabor alone in 1971. This paper focuses on the difficulties experienced in constructing a meaningful subject, a practical application and a viable technical community from Gabor’s ideas during the decade 1947-1957

A Renormalisation group for TCSA

We discuss the errors introduced by level truncation in the study of boundary renormalisation group flows by the Truncated Conformal Space Approach. We show that the TCSA results can have the qualitative form of a sequence of RG flows between different conformal boundary conditions. In the case of a perturbation by the field phi(13), we propose a renormalisation group equation for the coupling constant which predicts a fixed point at a finite value of the TCSA coupling constant and we compare the predictions with data obtained using TBA equations.Comment: 11 pages, 7 figures, talk presented by G Watts at the workshop "Integrable Models and Applications: from Strings to Condensed Matter", Santiago de Compostela, Spain, 12-16 September 200

Ultrafast photocurrent measurement of the escape time of electrons and holes from carbon nanotube PN junction photodiodes

Ultrafast photocurrent measurements are performed on individual carbon nanotube PN junction photodiodes. The photocurrent response to sub-picosecond pulses separated by a variable time delay {\Delta}t shows strong photocurrent suppression when two pulses overlap ({\Delta}t = 0). The picosecond-scale decay time of photocurrent suppression scales inversely with the applied bias VSD, and is twice as long for photon energy above the second subband E22 as compared to lower energy. The observed photocurrent behavior is well described by an escape time model that accounts for carrier effective mass.Comment: 8 pages Main text, 4 Figure

A wavefunction model to chemical bonding

In this paper we give a brief survey on some specific aspects of a wavefunction model for chemical bonding which are connected to or have been motivated in part by the work of the late Istvan Mayer and colleagues. After a brief description of the early wavefunction models as reflected in Mayer's works, naturally leading to electron densities, we discuss localized molecular orbitals, and summarize some of the early initiatives and applications. The concept of the Chemical Hamiltonian, as introduced by Mayer, its extensions and some classical and some more advanced connections will be discussed. The twofold motivating role of Mayer in the development of the earliest, ab initio level macromolecular linear scaling methods, giving proven "ab initio quality" protein energy results by the adjustable density matrix assembler method, and in some other molecular fragment advances will be also pointed out

The role of the cytoskeleton in the formation and properties of membrane tethers

Abstract only availableMembrane tethers play a critical role in cell adhesion and cell motility. This can be observed in the arrest of neutrophils on the endothelial wall of blood vessels during inflammatory response. Tethers are employed to slow down neutrophils when they are attracted to the periphery of the vessels due to chemotactic gradients set up by cytokines. As a result of slowing down, the neutrophil has time to form specific bonds with endothelial cells and start extravasating from the circulatory system into the surrounding tissue. Metastasizing cancer cells use a similar mechanism. A wide array of factors affects the mechanical characteristics of tethers. A major contribution is provided by the interaction between the cytoskeleton and the membrane. Interbilayer slip and the interaction between the membrane and the glycocalix are additional determinants of tether properties. Previous studies have shown a strong dependence of force needed to extract and pull a tether on the interaction between the membrane and the cytoskeleton. It has also been shown that disrupting the integrity of the cytoskeleton significantly reduces the tether force. The focus of this study was to further elucidate the contribution of the cytoskeleton-lipid bilayer interaction to the tether force, in particular how it affects cell membrane surface viscosity. Atomic Force Microscopy based force spectroscopy was used to determine the tether force and surface viscosity of the membrane prior and after the actin microfilament system had been depolyermerized by latrunculin-A. Two cells lines, Chinese Hamster Ovary (CHO) and Human Brain tumor (HB) cells were investigated. The tether force was determined when the membrane was stretched by a cantilever moving at a constant velocity over a range 3 to 21 micron/s. Surface viscosity was obtained from the slope of the linear force-speed curve. Quantitative information on tether forces and membrane surface viscosities allow for a better understanding of the mechanism responsible for the arrest of neutrophils during their attachment to the endothelial wall.NSF-REU Biosystems Modelin

Effects of telemonitoring on glycaemic control and healthcare costs in type 2 diabetes: a randomised controlled trial

Introduction: This study examined the effect of a telehealth intervention on the control of type 2 diabetes, and subsequent potential cost-savings to the health system. Methods: This prospective randomised controlled trial randomised adults with type 2 diabetes to the intervention (diabetes program) or control (usual care) arm. Key eligibility criteria included an HbA1c level of at least 58 mmol/mol (7.5%) without severe or unstable comorbidities. All participants continued their usual healthcare, but participants in the intervention arm received additional diabetes care from a diabetes care coordinator via a home monitor that captured clinical measures. Data collected included biomedical, quality of life measures and healthcare (GP, outpatient and inpatient) costs. The primary outcome was HbA1c collected at baseline and six-months. Analysis was conducted on a complete case intention-to-treat basis. The healthcare system perspective was taken to calculate the incremental cost per percentage-point reduction in HbA1c. Results: Results from 63 participants from each study arm were analysed. HbA1c in the intervention group decreased from a median 68 mmol/mol (8.4%) to 58 mmol/mol (7.5%), and remained unchanged in the control group at median 65 mmol/mol (8.1%) at the six-month endpoint. The intervention effect on HbA1c change was statistically significant (p=0.004). Total healthcare costs in the intervention group, including the intervention costs, were lower (mean $3,781 vs$4,662; p<0.001) compared to usual care. Discussion: There was a clinically meaningful and statistically significant benefit from the telehealth intervention at a lower cost; thus, telehealth was cost-saving and produced greater health benefits compared to usual care