Long-lived selective spin echoes in dipolar solids under periodic and aperiodic pi-pulse trains

The application of Carr-Purcell-Meiboom-Gill (CPMG) $\pi-$trains for dynamically decoupling a system from its environment has been extensively studied in a variety of physical systems. When applied to dipolar solids, recent experiments have demonstrated that CPMG pulse trains can generate long-lived spin echoes. While there still remains some controversy as to the origins of these long-lived spin echoes under the CPMG sequence, there is a general agreement that pulse errors during the $\pi-$pulses are a necessary requirement. In this work, we develop a theory to describe the spin dynamics in dipolar coupled spin-1/2 system under a CPMG($\phi_{1},\phi_{2}$) pulse train, where $\phi_{1}$ and $\phi_{2}$ are the phases of the $\pi-$pulses. From our theoretical framework, the propagator for the CPMG($\phi_{1},\phi_{2}$) pulse train is equivalent to an effective ``pulsed'' spin-locking of single-quantum coherences with phase $\pm\frac{\phi_{2}-3\phi_{1}}{2}$, which generates a periodic quasiequilibrium that corresponds to the long-lived echoes. Numerical simulations, along with experiments on both magnetically dilute, random spin networks found in C$_{60}$ and C$_{70}$ and in non-dilute spin systems found in adamantane and ferrocene, were performed and confirm the predictions from the proposed theory.Comment: 25 pages, 12 figures, submitted to Physical Review

A “trigger”, a cause or obscured? How trauma and adversity are constructed in psychiatric stress-vulnerability accounts of “psychosis”

How do mental health professionals link adverse life experiences with the kinds of beliefs and experiences which attract a diagnosis of psychosis and what implications does this have for women with these diagnoses? Drawing on a broadly critical realist framework, we present data from two studies relevant to these questions. First, we analyse the discursive practices engaged in during a staff-only discussion of a female in-patient with a psychosis diagnosis who had been raped some years previously. Staff oriented to the irrationality and factuality of her ostensibly delusional statements about rape and pregnancy in the present and formulated adverse experience as a ‘stress factor’ triggering a manic episode, thereby precluding alternative contextualising interpretations. In a second, interview-based, study, psychiatrists drew on a range of discursive resources which differentiated psychosis from other forms of distress, constructed trauma as a stressor which could trigger psychosis because of a genetic predisposition, and constructed medication as the primary intervention whilst a focus on trauma was de-emphasised. We discuss the implications of these findings for the kinds of explanations and forms of help offered and suggest ways in which distress might be contextualised as well as possible future directions for feminist research and practic

secCl is a cys-loop ion channel necessary for the chloride conductance that mediates hormone-induced fluid secretion in Drosophila

Organisms use circulating diuretic hormones to control water balance (osmolarity), thereby avoiding dehydration and managing excretion of waste products. The hormones act through G-protein-coupled receptors to activate second messenger systems that in turn control the permeability of secretory epithelia to ions like chloride. In insects, the chloride channel mediating the effects of diuretic hormones was unknown. Surprisingly, we find a pentameric, cys-loop chloride channel, a type of channel normally associated with neurotransmission, mediating hormone-induced transepithelial chloride conductance. This discovery is important because: 1) it describes an unexpected role for pentameric receptors in the membrane permeability of secretory epithelial cells, and 2) it suggests that neurotransmitter-gated ion channels may have evolved from channels involved in secretion

Structural and optical properties of MOCVD AllnN epilayers

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Special needs dentistry within the dental curriculum

Abstract no. 1682published_or_final_versio

Development of the South Canterbury / Otago southern bluefin tuna fishery

There is concern that many of New Zealand's inshore fish species are being overfished to the extent that fishing effort will have to be reduced to ensure the continued existence of some species as commercial stocks. A dual solution of both reducing the total level of fishing effort and transferring fishing effort to alternative fisheries to alleviate the problem is possible. This report examines the economics of transferring fishing effort to southern bluefin tuna capture off the South Canterbury / Otago coast, and is therefore an example of the problems and potential in transferring fishing effort. The study pays particular attention to the extension needs in developing fisheries using the results of a census of skippers in the region. Two chapters have been included to give the reader some background to the southern bluefin tuna fishery and the South Canterbury/Otago fishery. From this information the potential benefits of development, the direct cost of catching bluefin and the opportunity cost of foregoing catching traditional species have been estimated. The indirect costs of providing the necessary infrastructure for development were estimated from the survey. The survey also provided information on the readiness of fishermen and their vessels to undertake southern bluefin tuna fishing. This paper does not consider the effect on the traditional fish stocks of transferring catching effort to alternative fisheries. However, consideration is given to the economics of transferring catching effort to alternative fisheries regardless of the reasons for having an effort reduction scheme. The cost benefit analysis has seven scenarios based on the extent to which developing the bluefin fishing is able to alleviate the present inshore fisheries management problems

Lesions mimicking lacrimal gland pleomorphic adenoma

Aim: To report a series of patients with lacrimal gland lesions simulating the clinicoradiological features of lacrimal gland pleomorphic adenoma (LGPA). Methods: Multicentre retrospective, interventional case series. Clinical records of all patients with lesions mimicking LGPA seen in five orbital units were reviewed. Results: The study included 14 patients (seven men and seven women) with a mean age of 50.9 years. The diagnosis of LGPA was made in all cases by experienced orbital surgeons, based on clinicoradiological features, and lacrimal gland excision was performed. Postoperative histology revealed lymphoma (four patients), chronic dacryoadenitis (three patients), adenoid cystic carcinoma (two patients), Sjogren's syndrome (two patients), cavernous haemangioma (one patient), benign lymphoid hyperplasia (one patient) and granulomatous dacryoadenitis (one patient). Comparison with the total number of histologically confirmed LGPA cases seen during the study period revealed that 22.6% of cases of suspected LGPA were misdiagnosed based on clinicoradiological criteria. Conclusions: Many different lesions may mimic the clinicoradiological features of LGPA. The accepted clinicoradiological criteria used for the diagnosis of LGPA have a high false-positive rate, even in experienced hands. Based on this study, the authors believe that fine-needle aspiration biopsy or intraoperative biopsy and frozen section diagnosis may help reduce unnecessary lacrimal gland excision.Venkatesh C Prabhakaran, Paul S Cannon, Alan McNab, Garry Davis, Brett O’Donnell, Peter J Dolman, Raf Ghabrial, Dinesh Selv

Zeeman splittings of the 5D0–7F2 transitions of Eu3+ ions implanted into GaN

We report the magnetic field splittings of emission lines assigned to the 5D0–7F2 transitions of Eu3+ centres in GaN. The application of a magnetic field in the c-axis direction (B||c) leads to a splitting of the major lines at 621 nm, 622 nm and 622.8 nm into two components. The Zeeman splitting is linear with magnetic field up to 5 Tesla for each line. In contrast, a magnetic field applied in the growth plane (B┴c) does not influence the photoluminescence spectra. The estimated g-factors vary slightly from sample to sample with mean values of g|| ~2.8, ~1.5 and ~2.0 for the emission lines at 621 nm, 622 nm and 622.8 nm respectively