Cavity-Enhanced Two-Photon Interference using Remote Quantum Dot Sources

Quantum dots in cavities have been shown to be very bright sources of indistinguishable single photons. Yet the quantum interference between two bright quantum dot sources, a critical step for photon based quantum computation, has never been investigated. Here we report on such a measurement, taking advantage of a deterministic fabrication of the devices. We show that cavity quantum electrodynamics can efficiently improve the quantum interference between remote quantum dot sources: poorly indistinguishable photons can still interfere with good contrast with high quality photons emitted by a source in the strong Purcell regime. Our measurements and calculations show that cavity quantum electrodynamics is a powerful tool for interconnecting several devices.Comment: 5 pages, 4 figures (Supp. Mat. attached

Chronic inflammation as a manifestation of defects in immunoregulatory networks: implications for novel therapies based on microbial products

Based on a unifying theory presented here, it is predicted that the immune defects resulting in chronic inflammation rather than effective immune responses could be rectified by the therapeutic use of agents prepared from micro-organisms. With appropriate molecular patterns, these should be able to induce protective immunoregulatory networks or to reprogramme defective ones. In contrast to acute inflammation, chronic inflammation appears to have no beneficial role, but is a state of sustained immune reactivity in the presence or progression of a disease process. This results in an escalating cycle of tissue damage followed by unproductive tissue repair, breaks in self-tolerance, malignant transformation or deleterious changes in tissue morphology and function. Such inappropriate immune reactivity is an underlying characteristic, either in initiation or maintenance, of a diverse range of disease states including chronic infection, autoimmunity, allergy, cancer, vascular disease and metabolic alterations. Evidence is presented that the inappropriate immune reactivity is due, at least to some extent, to failures in the establishment of immunoregulatory networks as a result of hygiene-related factors. Such networks are the result of activation of antigen-presenting cells, principally dendritic cells, by molecular patterns of micro-organisms encountered sequentially during life and establishing the "biography" of the immune system.Fil: Bottasso, Oscar Adelmo. Universidad Nacional de Rosario. Facultad de Ciencias Médicas. Instituto de Inmunología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Docena, Guillermo H.. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; ArgentinaFil: Stanford, J. L.. University College London; Estados UnidosFil: Grange, J. M.. University College London; Estados Unido

The Nature and Purpose of Acute Psychiatric Wards: The Tompkins Acute Ward Study

Background: Acute inpatient care in the UK is being subjected to increasing critical scrutiny, highlighting concerns about content and quality. There is an absence of clarity and consensus on what acute inpatient care is for, adding to difficulties in developing this service sector. Aim: To define the function of acute psychiatric wards. Methods: Interviews were conducted with multidisciplinary staff (13 Ward Managers, 14 F Grade nurses, 11 Occupational Therapists and 9 Consultant Psychiatrists), on rationales for admission, their care and treatment philosophy, and the roles of different professionals. Results: Patients are admitted because they appear likely to harm themselves or others, and because they are suffering from a severe mental illness, and/or because they or their family/community require respite, and/or because they have insufficient support and supervision available to them in the community. The tasks of acute inpatient care are to keep patients safe, assess their problems, treat their mental illness, meet their basic care needs and provide physical healthcare. These tasks are completed via containment, 24-hour staff presence, treatment provision, and complex organisation and management. Conclusions: Professional education, audit, research and the structuring of services all need to be oriented towards these tasks. Declaration of interest: This study was funded by the Tompkins Foundation and the Department of Health Nursing Quality initiative

Intersublevel Polaron Dephasing in Self-Assembled Quantum Dots

Polaron dephasing processes are investigated in InAs/GaAs dots using far-infrared transient four wave mixing (FWM) spectroscopy. We observe an oscillatory behaviour in the FWM signal shortly (< 5 ps) after resonant excitation of the lowest energy conduction band transition due to coherent acoustic phonon generation. The subsequent single exponential decay yields long intraband dephasing times of 90 ps. We find excellent agreement between our measured and calculated FWM dynamics, and show that both real and virtual acoustic phonon processes are necessary to explain the temperature dependence of the polarization decay.Comment: 10 pages, 4 figures, submitted to Phys Rev Let

Enhancing malaria control using a computerised management system in southern Africa

BACKGROUND: Malaria control programmes utilising indoor residual spraying are only effective if a high coverage of targeted structures is achieved and an insecticide that is effective against the specific mosquito vector is correctly applied. Ongoing monitoring of spraying operations is essential to assure optimal programme performance and early corrective action, where indicated. METHODS: Successful development and application of a computerised spraying operations management system in Mpumalanga Province, South Africa during 1998 resulted in its adaptation and introduction in neighbouring Maputo Province, southern Mozambique during 2000. The structure and components of this computerised management system are described, and its' operational benefit in southern Mozambique, where community-based spray operators apply intradomiciliary insecticide, are reviewed. CONCLUSIONS: The computerised management system allowed malaria programme management and field supervisors to monitor spraying coverage, insecticide consumption and application rates on an ongoing basis. The system supported a successful transition to community-based spraying, while assuring correct insecticide application and spraying completion according to schedule

Modeling of mode-locking in a laser with spatially separate gain media

We present a novel laser mode-locking scheme and discuss its unusual properties and feasibility using a theoretical model. A large set of single-frequency continuous-wave lasers oscillate by amplification in spatially separated gain media. They are mutually phase-locked by nonlinear feedback from a common saturable absorber. As a result, ultra short pulses are generated. The new scheme offers three significant benefits: the light that is amplified in each medium is continuous wave, thereby avoiding issues related to group velocity dispersion and nonlinear effects that can perturb the pulse shape. The set of frequencies on which the laser oscillates, and therefore the pulse repetition rate, is controlled by the geometry of resonator-internal optical elements, not by the cavity length. Finally, the bandwidth of the laser can be controlled by switching gain modules on and off. This scheme offers a route to mode-locked lasers with high average output power, repetition rates that can be scaled into the THz range, and a bandwidth that can be dynamically controlled. The approach is particularly suited for implementation using semiconductor diode laser arrays.Comment: 13 pages, 5 figures, submitted to Optics Expres

The configuration of the seismic zone and the downgoing slab in southern Peru

Using data from temporary networks of portable seismographs in southern Peru, we located 888 shallow and intermediate depth events near a proposed discontinuity in the seismic zone there. These events reveal a prominent contortion, instead of a discontinuity, that trends approximately N80°E, parallel to the direction of relative plate motion. North of about 15°S, the seismic zone beneath Peru is nearly horizontal, but south of about 15.5°S, it dips at about 25°. Volcanoes lie above the more steeply dipping zone where earthquakes occur between 120 and 140 km, and the volcanic line in southern Peru stops abruptly at the contortion

Preventing ice-dams on Minnesota homes

1 online resource (PDF, 2 pages)This archival publication may not reflect current scientific knowledge or recommendations. Current information available from the University of Minnesota Extension: https://www.extension.umn.edu