Calculation of Projected Bond-Orientational Order Parameters to Quantify Local Symmetries from Transmission Diffraction Data.

The bond-orientational order parameters introduced by Steinhardt et al. [Phys. Rev. B 28, 784 (1983)] have been an invaluable measurement tool for assessing short-range order in disordered, close-packed assemblies of particles in which the particle positions are known. In many glassy systems the measurement of particle position is not possible or limited (field of view, thickness, resolution) and the bond-orientational order parameters cannot be measured, or adequately sampled. Here we calculate a set of rotationally averaged, projected bond-orientational order parameters that reflect the symmetries of close-packed particle clusters when projected onto a plane. We show by simulation that these parameters are unique fingerprints that can be directly compared to angular correlations in limited-volume, transmission geometry, diffraction patterns from close-packed glassy assemblies.

Publisher's Note: Calculation of Projected Bond-Orientational Order Parameters to Quantify Local Symmetries from Transmission Diffraction Data [Phys. Rev. Lett. 116, 205501 (2016)].

This corrects the article DOI: 10.1103/PhysRevLett.116.205501.

SEM Analysis of MTAD Efficacy for Smear Layer Removal from Periodontally Affected Root Surfaces.

OBJECTIVE: Biopure® MTAD (Dentsply Tulsa Dental, USA) has been developed as a final irrigant following root canal shaping to remove intracanal smear layer. Many of the unique properties of MTAD potentially transfer to the conditioning process of tooth roots during periodontal therapy. The aim of this ex vivo study was to evaluate the effect of MTAD on the removal of smear layer from root surfaces. MATERIALS AND METHODS: Thirty two longitudinally sectioned specimens from 16 freshly extracted teeth diagnosed with advanced periodontal disease were divided into four groups. In group 1 and 2, the root surfaces were scaled using Gracey curettes. In group 3 and 4, 0.5 mm of the root surface was removed using a fissure bur. The specimens in group 1 and 3 were then irrigated by normal saline. The specimens in groups 2 and 4 were irrigated with Biopure MTAD. All specimens were prepared for SEM and scored according to the presence of smear layer. RESULTS: MTAD significantly increased (P=0.001) the smear layer removal in both groups 2 and 4 compared to the associated control groups, in which only saline was used. CONCLUSION: MTAD increased the removal of the smear layer from periodontally affected root surfaces. Use of MTAD as a periodontal conditioner may be suggested.

An evaluation of the effect of blood and human serum on the surface microhardness and surface microstructure of mineral trioxide aggregate.

AIM: Short-term and long-term evaluation of the effect of whole human blood or serum contamination on the surface microhardness value and microstructure of white and grey mineral trioxide aggregate (MTA). METHODOLOGY: Three groups of 10 samples for each type of MTA were prepared. The first group was mixed with and exposed to fresh whole human blood. The second and third groups were mixed with distilled water and exposed to fresh whole human blood or human serum, respectively. The control group samples were mixed with and exposed to distilled water. During preparation, 1 g of MTA was triturated with 0.33 g of the selected liquid using an amalgamator and placed inside borosilicate cylindrical moulds. The samples were treated with ultrasonic energy. Vickers surface microhardness values were compared after 4 and 180 days. Scanning electron microscopy (SEM) analysis was performed after 4 days. RESULTS: White MTA had a greater microhardness value than grey MTA in all groups. There was a significant difference between the control and the experimental groups (P < 0.00001). There was no significant difference between the microhardness values obtained after 4 and 180 days, apart from grey MTA mixed with blood or exposed to serum (P < 0.00001). SEM analysis showed the contaminated samples were devoid of acicular crystals that were prominent in the control groups. CONCLUSION: Blood contamination had a detrimental effect on the surface microhardness of MTA in the short and long term. If blood or serum contamination is unavoidable under clinical conditions, it might be preferable to use white MTA.

Early visual experience and the receptive-field organization of optic flow processing interneurons in the fly motion pathway.

The distribution of local preferred directions and motion sensitivities within the receptive fields of so-called tangential neurons in the fly visual system was previously found to match optic flow fields as induced by certain self-motions. The complex receptive-field organization of the tangential neurons and the recent evidence showing that the orderly development of the fly's peripheral visual system depends on visual experience led us to investigate whether or not early visual input is required to establish the functional receptive-field properties of such tangential neurons. In electrophysiological investigations of two identified tangential neurons, it turned out that dark-hatched flies which were kept in complete darkness for 2 days develop basically the same receptive-field organization as flies which were raised under seasonal light/dark conditions and were free to move in their cages. We did not find any evidence that the development of the sophisticated receptive-field organization of tangential neurons depends on sensory experience. Instead, the input to the tangential neurons seems to be "hardwired" and the specificity of these cells to optic flow induced during self-motions of the animal may have evolved on a phylogenetical time scale.

Survey of moonlighting practices and work requirements of emergency medicine residents.

We conducted an anonymous moonlighting and academic practice survey of all emergency medicine residents enrolled in accredited programs during 1997. Expanding on previous work, this survey included specific details and practice trends of moonlighting emergency medicine residents and for comparison also included academic work requirements. The typical emergency residency program requires residents to work 204 hours monthly. However, the range of required work-hours is strikingly large (120-300). Half of emergency medicine residents moonlight. The typical moonlighting resident works as a solo emergency department practitioner in multiple facilities outside of residency-affiliated institutions. Moonlighting salaries generally double a resident's annual income and are used to pay off student loans and other debt. Residents with higher student debt are more likely to moonlight. Despite the fact that most residency programs restrict moonlighting, a majority of moonlighting residents have violated an Accreditation Council for Graduate Medical Education prohibition restricting work within one period of a regular residency-scheduled shift. Half of all residents surveyed, whether involved in moonlighting practice or not, would violate a ban on the practice. Residents universally felt that moonlighting enhanced residency performance and was a positive educational experience. Use of these data may aid in the development of formal guidelines regarding emergency medicine moonlighting practice.

Communicating quality improvement through a hospital newsletter.

Healthcare organizations across the United States are embracing the tenets of continuous quality improvement. The challenge is to disseminate information about this quality activity throughout the organization. A monthly newsletter serves two vital purposes: to share the improvements and to generate more enthusiasm and participation by staff members. This article gives practical suggestions for promoting a monthly newsletter. Preparation of an informative newsletter requires a significant investment of time and effort. However, the positive results of providing facilitywide communications can make it worth the effort. The current availability of relatively inexpensive desktop publishing computer software programs has made the process much easier.

Neurochemical properties of AHR-9377: a novel inhibitor of norepinephrine reuptake.

A novel potential antidepressant, AHR-9377, was evaluated for its inhibition of norepinephrine (NE), serotonin (5-HT) and dopamine (DA) reuptake in hypothalmic, cortical, and striatal rat synaptosomal preparations. AHR-9377 was found to be a potent, selective, noncompetitive inhibitor of NE reuptake. In addition, repeated injections of AHR-9377 caused a decrease in the density of beta adrenergic receptors in rat cerebral cortex. Little displacement by AHR-9377 at beta, alpha 1 and alpha 2 adrenergic, histaminergic, muscarinic, GABA-ergic, benzodiazepine of imipramine sites was observed. These pharmacological properties indicate that AHR-9377 may have clinical antidepressant activity with few side effects.

Simultaneous determination of vitamins B1, B2, B6, and niacinamide in multivitamin pharmaceutical preparations by paired-ion reversed-phase high-pressure liquid chromatography.

A high-pressure liquid chromatographic procedure for the simultaneous determination of vitamins B1, B2, B6, and niacinamide in multivitamin pharmaceutical preparations was developed and evaluated. The method uses paired-ion reversed-phase partition chromatography for baseline separation of the four water-soluble vitamins. This method was applied to the analysis of a multivitamin and multivitamin-multimineral tablets, and a technique was developed to reduce vitamin adsorption by the minerals. The results obtained by this method were compared with those obtained by the official methods. It was concluded that this method is fast, accurate, specific, and suitable for routine quality control use.

Signal to noise ratio and response variability measurements in single trial evoked potentials.

Techniques were developed for measurement of signal to noise ratio and response variability in single trial evoked potentials. These techniques were extended and verified using a digital computer simulation of signal plus noise trials. When applied to real data the measures appear to have high reliability and to demonstrate that human evoked potentials are more variable than would be expected from background noise variation alone. Empirical equations are presented which can be applied to existing single trial EP data to estimate both signal-to-noise ratio and its expected variance.

The services of a hospital medical library.

The purpose of a hospital medical library is described under the headings of diagnostic and treatment guide, current awareness and access to published literature. The Wessex Regional Library and Information Services is described.