Symmetry in the insulator - quantum Hall - insulator transitions observed in a Ge/SiGe quantum well

We examine the magnetic field driven insulator-quantum Hall-insulator transitions of the two dimensional hole gas in a Ge/SiGe quantum well. We observe direct transitions between low and high magnetic field insulators and the $\nu=1$ quantum Hall state. With increasing magnetic field, the transitions from insulating to quantum Hall and quantum Hall to insulating are very similar with respect to their transport properties. We address the temperature dependence around the transitions and show that the characteristic energy scale for the high field transition is larger.Comment: 4 page

Optic disc pit maculopathy: a two-year nationwide prospective study.

Purpose To identify the incidence, presenting features, treatment, and clinical course of optic disc pit maculopathy (ODPM) in the United Kingdom (UK). Design A 2-year nationwide prospective population-based study. Subjects All new incident cases of ODPM presenting to UK ophthalmologists using the British Ophthalmic Surveillance Unit monthly reporting system. Methods All reporting ophthalmologists were sent an initial questionnaire requesting data on previous medical and ophthalmic history, presentation details, investigation findings, and management. A further questionnaire was sent at 12 months post diagnosis to ascertain further outcome data. Main Outcome Measures Visual acuity at initial presentation, at 1 year, and after any intervention. Foveal involvement and optical coherence tomography (OCT) findings, including retinal layers affected, and the location and size of the optic disc pit. Management, including observation, vitrectomy, and associated procedures. Results There were 74 confirmed new cases, giving an annual incidence of approximately 1 per 2 million. Complete data were available on 70 patients (70 eyes) at baseline and 68 after 1 year. There were 35 (50%) female patients with a mean age of 35 years (range, 3–82 years). Visual acuity at baseline ranged from 6/5 to hand movements. In 43 patients (61%) subretinal fluid (SRF) was present, whereas 27 (39%) had intraretinal fluid only. The presence of SRF was associated with worse vision and foveal involvement. Of the 53 eyes initially observed with 1-year follow-up, 10 (19%) deteriorated and 9 (16%) improved on OCT; eyes with SRF were more likely to worsen and those without SRF were more likely to improve. Fifteen of the 70 patients (21%) at baseline had primary surgery and a further 10 had deferred surgery within 1 year of presentation; 19 of these 25 eyes (76%) showed anatomic success with a dry fovea at 1 year of follow-up, and 15 (60%) had a greater than 0.1 logMAR improvement in visual acuity. Conclusion The incidence and presenting features of ODPM were defined. Patients with SRF had worse vision and were more likely to deteriorate than patients with intraretinal fluid only. Surgery was anatomically successful in 75% of cases. Patients without SRF tended to remain stable with observation

A plasticity model for powder compaction processes incorporating particle deformation and rearrangement

This article is available open access through the publisher’s website at the link below. Copyright @ 2008 Elsevier Ltd.This paper develops a mechanistic model of granular materials that can be used with a commercial finite element package (ABAQUS). The model draws on the ideas of critical state soil mechanics and combines them with the theory of envelopes to develop an elasto-plastic model with a non-associated flow rule. The model incorporates both local deformation at the granule contacts, and rearrangement of the granules so that jointly they account for any bulk deformation. The mechanics of the model closely reflect the physicality of the material behaviour and the model parameters are closely linked (although not simplistically identical) to the characteristics of the granules. This not only gives an insight into the material behaviour, but also enables the model to be used to facilitate design of the material, its processing properties and, hence, component development. The model is used to simulate drained triaxial tests, settlement of a powder in a bin, and some examples of die pressing. Simulations are compared with experimental data and with predictions obtained using other models

Parity-violating neutron spin rotation in hydrogen and deuterium

We calculate the (parity-violating) spin rotation angle of a polarized neutron beam through hydrogen and deuterium targets, using pionless effective field theory up to next-to-leading order. Our result is part of a program to obtain the five leading independent low-energy parameters that characterize hadronic parity-violation from few-body observables in one systematic and consistent framework. The two spin-rotation angles provide independent constraints on these parameters. Using naive dimensional analysis to estimate the typical size of the couplings, we expect the signal for standard target densities to be 10^-7 to 10^-6 rad/m for both hydrogen and deuterium targets. We find no indication that the nd observable is enhanced compared to the np one. All results are properly renormalized. An estimate of the numerical and systematic uncertainties of our calculations indicates excellent convergence. An appendix contains the relevant partial-wave projectors of the three-nucleon system.Comment: 44 pages, 17 figures; minor corrections; to be published in EPJ

Revisiting the Hugenholtz-Van Hove theorem in nuclear matter

An assessment of the magnitude of the rearrangement contribution to the Fermi energy and to the binding energy per particle is carried out in symmetric nuclear matter by extending the G-matrix framework. The restoration of the thermodynamic consistency or, equivalently, the fulfillment of the Hugenholtz-Van Hove theorem, is discussed.Comment: 14 pages, 3 figure

Spatial and temporal distribution characteristics of different forms of inorganic nitrogen in three types of rivers around Lake Taihu, China

In order to control nitrogen (N) pollution of Lake Taihu, China, we studied the spatial and temporal distribution characteristics of inorganic N in inflowing rivers polluted by industry, agriculture, and domestic sewage during low, moderate, and high flow periods. The results showed that dissolved total nitrogen (DTN) was the main fraction of total nitrogen (TN) input from these rivers. Inflowing rivers had distinct impacts on TN, DTN, ammonium N (NH 4 + ), and nitrate N (NO 3 − ) concentrations of Lake Taihu during the low flow period. Particulate nitrogen (PN) had an impact on Lake Taihu during the three flow periods and all the three types of rivers would increase PN concentration in the lake. Rivers polluted by agriculture had the greatest impact on Lake Taihu’s TN, DTN, NO 3 − , and dissolved inorganic N (DIN) concentrations, while rivers polluted by industry had the greatest impact on NH 4 + concentration. Therefore, agriculture and industry should be key targets for nutrient reductions. The in-lake N concentrations were higher than those of inflowing rivers during moderate and high flow periods

A study of bioavailable phosphorus in the inflowing rivers of Lake Taihu, China

Phosphorus (P) is a vital nutrient for algal growth. Aside from soluble reactive P (SRP), organic P (OP) is used by algae via alkaline phosphatase (AP) hydrolysis, which can play an important role in supplying P. Enzymatically-hydrolysable OP (EHP) can potentially be used as an indicator of bioavailability of P other than SRP in natural waters. We investigated the ecological significance of alkaline phosphatase activity (APA), EHP concentration and P turnover time in the inflowing rivers of Lake Taihu (Taihu) during three hydrologic periods. Results indicated high SRP concentration and low SRP demand by algal suppressed APA in the inflowing rivers, the highest proportion of OP mineralization rate (v) to the maximum reaction velocity of AP (Vmax) is only 14.7%. P turnover time of the inflowing rivers was generally from 3 to 7 days and in exceptional cases, it could exceed 10 days. The high EHP reserve and the sufficient AP for OP mineralization render the rivers a significant source of utilizable OP, further exacerbating eutrophication of Taihu

Thermal photons as a measure for the rapidity dependence of the temperature

The rapidity distribution of thermal photons produced in Pb+Pb collisions at CERN-SPS energies is calculated within scaling and three-fluid hydrodynamics. It is shown that these scenarios lead to very different rapidity spectra. A measurement of the rapidity dependence of photon radiation can give cleaner insight into the reaction dynamics than pion spectra, especially into the rapidity dependence of the temperature.Comment: 3 Figure

Multipartite entanglement for entanglement teleportation

The scheme for entanglement teleportation is proposed to incorporate multipartite entanglement of four qubits as a quantum channel. Based on the invariance of entanglement teleportation under arbitrary two-qubit unitary transformation, we derive relations of separabilities for joint measurements at a sending station and for unitary operations at a receiving station. From the relations of separabilities it is found that an inseparable quantum channel always leads to a total teleportation of entanglement with an inseparable joint measurement and/or a nonlocal unitary operation.Comment: slightly modifie