A quantum interface between light and nuclear spins in quantum dots

The coherent coupling of flying photonic qubits to stationary matter-based qubits is an essential building block for quantum communication networks. We show how such a quantum interface can be realized between a traveling-wave optical field and the polarized nuclear spins in a singly charged quantum dot strongly coupled to a high-finesse optical cavity. By adiabatically eliminating the electron a direct effective coupling is achieved. Depending on the laser field applied, interactions that enable either write-in or read-out are obtained.Comment: 10 pages, 5 figures, final versio

Utilisation and usefulness of face composites in the South African Police Service - an evaluation study

The current study investigates the degree to which face composites are utilised as an investigative tool in the South African Police Service. The article provides an overview of the conditions under which composites are produced by eyewitnesses to a crime, and points out constraints in terms of their usefulness and applicability. Composites were found to be produced after a longer delay than is recommended, and predominantly in violent and menacing crimes. Conviction rates for composite-related crimes were very low. However, more insight into actual use and case characteristics is needed before concluding on the usefulness of composites as an investigative tool or evidence. Directions for further research in this area are explored

NGTS-4b: A sub-Neptune transiting in the desert

We report the discovery of NGTS-4b, a sub-Neptune-sized planet transiting a 13th magnitude K-dwarf in a 1.34 d orbit. NGTS-4b has a mass M = 20.6 ± 3.0 M⊕ and radius R = 3.18 ± 0.26 R⊕, which places it well within the so-called ‘Neptunian Desert’. The mean density of the planet (3.45 ± 0.95 g cm−3) is consistent with a composition of 100  per cent H2O or a rocky core with a volatile envelope. NGTS-4b is likely to suffer significant mass loss due to relatively strong EUV/X-ray irradiation. Its survival in the Neptunian desert may be due to an unusually high-core mass, or it may have avoided the most intense X-ray irradiation by migrating after the initial activity of its host star had subsided. With a transit depth of 0.13 ± 0.02 per cent, NGTS-4b represents the shallowest transiting system ever discovered from the ground, and is the smallest planet discovered in a wide-field ground-based photometric survey

Elimination of Dietary Gluten Does Not Reduce Titers of Type 1 Diabetes-Associated Autoantibodies in High-Risk Subjects

OBJECTIVE—Removal of the dietary wheat protein gluten protects against autoimmune diabetes in animal models. Furthermore, elimination of dietary gluten reduces the frequency of type 1 diabetes in patients with celiac disease. Herein we test the hypothesis that gluten is the driving antigen for type 1 diabetes-associated islet autoimmunity.RESEARCH DESIGN AND METHODS—Seven autoantibody-positive, first-degree relatives of patients with type 1 diabetes were placed on a gluten-free diet for 12 months followed by gluten reexposure for 12 months. Gliadin antibodies as well as the diabetes-related antibodies insulin autoantibody (IAA), GAD antibody (GADA), and tyrosin phosphatase IA2 antibody (IA-2A) were measured every 3 months; oral glucose tolerance tests were performed every 6 months. Changes in autoantibody titers were compared with those observed in a matched historical cohort.RESULTS—A reduction in IgG gliadin antibody titers was observed during the gluten-free period, but titers of diabetes-associated autoantibodies changed independently of gluten exposure. Type 1 diabetes-associated islet autoantibody levels at the end of the gluten-free diet period were not significantly different from those before commencement of the diet (P = 0.2) or at the end of the gluten reexposure period (P = 0.4). Changes in individual subjects were identified, but no differences were noted between the gluten-free and the gluten re-exposure periods, and the changes were similar to those observed in the historical control cohort (P = 1.0). Major titer reductions (>50%) in the gluten-free period were observed in only one subject for all antibodies. Type 1 diabetes developed in this subject and in a second subject during the gluten reexposure period.CONCLUSIONS—The findings do not support the hypothesis that gluten is a driving antigen in type 1 diabetes

Does ultrasonic dispersion and homogenization by ball milling change the chemical structure of organic matter in geochemical samples?—a CPMAS 13C NMR study with lignin

6 pages, 2 figures, 2 tables, 23 references.Ultrasonic dispersion of geochemical samples suspended in water and subsequent homogenization by ball milling is widely used for fractionation of organic matter. The effect of these treatments on organic matter is investigated with lignin as a model compound. Structural alterations detectable by solid-state 13C nuclear magnetic resonance (NMR) spectroscopy were examined. Comparison of the solid-state 13C NMR spectra of untreated lignin and lignin mixed with quartz or soil did not reveal evidence for structural changes in the organic matter composition after ultrasonic dispersion and subsequent ball-milling. The chemical structure of organic matter in geochemical samples is not affected by these treatments as far as such structural alterations can be detected by solid-state 13C NMR spectroscopy.This work was financially supported by the Deutsche Forschungsgemeinschaft (Ko 1035/6-land 2) and the Deutscher Akademischer Austauschdienst (Ref. 315, D/94/16993).Peer reviewe