1,471 research outputs found
Antecedents and Outcomes of End User Computing Competence
The tremendous proliferation of end user computing (EUC) in the workplace over the past few decades is cause for concern in public and private organizations. Computer use has moved from individuals working with dumb terminals in centralized networks to individuals operating personal computers, just as powerful as yesterday\u27s mainframe. The end user has had to evolve and will continue evolving as well; from someone with low level technical skills to someone with a high level of technical knowledge and information managerial skills. Because EUC continues growing more sophisticated, end users must not only maintain a level of competence, but prepare for the next generation of computing technology. Doing so will enable organizations to continue enjoying the positive benefits of EUC success. Research indicates that EUC success may depend on end user competence. Using Structural Equation Modeling (SEM) to test an integrated model of EUC success, the results of this study show that computer training, education level, beliefs about computer systems and the ability to operate them lead to end user computing competence. Additionally, results show that computer system use, a factor in achieving EUC success, is an outcome of end user computing competence. The overall conclusions drawn from this study is that the Air Force organization may be able to improve its efforts to successfully use computing technology, however it appears individual personnel have the competence to do so already. There may be additional underlying factors contributing to the lack of significant computing success, the discovery of which is a prospect for future research
Relativistic Scattered Wave Calculations on UF\u3csub\u3e6\u3c/sub\u3e
Selfāconsistent DiracāSlater multiple scattering calculations are presented for UF6. These are the first such calculations to be reported, and the results are compared critically to other relativistic calculations. The results of all molecular orbital calculations are in good qualitative agreement, as measured by energy levels, population analyses, and spināorbit splittings. The overall charge distribution is computed to be U+1.5(Fā0.25)6. Polarization functions are found to be qualitatively unimportant. A detailed comparison is made to the relativistic XĪ± (RXĪ±) method of Wood and Boring, which also uses multiple scattering theory, but incorporates relativistic effects in a more approximate fashion. For the most part, the RXĪ± results are in excellent agreement with the present results. Some differences of possible significance are noted in the lower valence and core energies
A real-time hybrid aurora alert system:combining citizen science reports with an auroral oval model
Accurately predicting when, and from where, an aurora will be visible is particularly difficult, yet it is a service much desired by the general public. Several aurora alert services exist that attempt to provide such predictions but are, generally, based upon fairly coarse estimates of auroral activity (e.g. Kp or Dst). Additionally, these services are not able to account for a potential observer's local conditions (such as cloud cover or level of darkness). Aurorasaurus, however, combines data from the well-used, solar wind driven, OVATION Prime auroral oval model with real-time observational data provided by a global network of citizen scientists. This system is designed to provide more accurate and localized alerts for auroral visibility than currently available. Early results are promising and show that over 100,000 auroral visibility alerts have been issued, including nearly 200 highly localized alerts, to over 2,000 users located right across the globe
Recommended from our members
Improved chemistry restraints for crystallographic refinement by integrating the Amber force field into Phenix.
The refinement of biomolecular crystallographic models relies on geometric restraints to help to address the paucity of experimental data typical in these experiments. Limitations in these restraints can degrade the quality of the resulting atomic models. Here, an integration of the full all-atom Amber molecular-dynamics force field into Phenix crystallographic refinement is presented, which enables more complete modeling of biomolecular chemistry. The advantages of the force field include a carefully derived set of torsion-angle potentials, an extensive and flexible set of atom types, Lennard-Jones treatment of nonbonded interactions and a full treatment of crystalline electrostatics. The new combined method was tested against conventional geometry restraints for over 22ā
000 protein structures. Structures refined with the new method show substantially improved model quality. On average, Ramachandran and rotamer scores are somewhat better, clashscores and MolProbity scores are significantly improved, and the modeling of electrostatics leads to structures that exhibit more, and more correct, hydrogen bonds than those refined using traditional geometry restraints. In general it is found that model improvements are greatest at lower resolutions, prompting plans to add the Amber target function to real-space refinement for use in electron cryo-microscopy. This work opens the door to the future development of more advanced applications such as Amber-based ensemble refinement, quantum-mechanical representation of active sites and improved geometric restraints for simulated annealing
A Grid-enabled web portal for NMR structure refinement with AMBER
Abstract
Motivation: The typical workflow for NMR structure determination involves collecting thousands of conformational restraints, calculating a bundle of 20ā40 conformers in agreement with them and refining the energetics of these conformers. The structure calculation step employs simulated annealing based on molecular dynamics (MD) simulations with very simplified force fields. The value of refining the calculated conformers using restrained MD (rMD) simulations with state-of-art force fields is documented. This refinement however presents various subtleties, from the proper formatting of conformational restraints to the definition of suitable protocols.
Results: We describe a web interface to set up and run calculations with the AMBER package, which we called AMPS-NMR (AMBER-based Portal Server for NMR structures). The interface allows the refinement of NMR structures through rMD. Some predefined protocols are provided for this purpose, which can be personalized; it is also possible to create an entirely new protocol. AMPS-NMR can handle various restraint types. Standard rMD refinement in explicit water of the structures of three different proteins are shown as examples. AMPS-NMR additionally includes a workspace for the user to store different calculations. As an ancillary service, a web interface to AnteChamber is available, enabling the calculation of force field parameters for organic molecules such as ligands in proteināligand adducts.
Availability and Implementation: AMPS-NMR is embedded within the NMR services of the WeNMR project and is available at http://py-enmr.cerm.unifi.it/access/index/amps-nmr; its use requires registration with a digital certificate.
Contact: [email protected]
Supplementary information: Supplementary data are available at Bioinformatics online
Excavations at cathole cave, Gower, Swansea
The discovery of an engraving in Cathole Cave in 2010 led to a decision to grille the cave. In 2012 excavations took place in the cave ahead of the grilling. Two areas of the cave were excavated; Trench A demonstrating that the cave held a faunal occupation dating to MIS 3, at a time, or times, between 50,000 and 30,000 BP. Two flint blades of Upper Palaeolithic appearance were discovered along with a faunal assemblage from within the shallow deposits across the line of the grille. The work demonstrated that the earlier excavations in the cave by Col. E.R. Wood were extensive and at this point in the cave he excavated to bedrock. The standing section (Trench B) which he left exposed further along the main cave passage was also cleaned, recorded and sampled. The deposits contain a faunal assemblage dominated by microfauna, but no cultural artefacts were found. The dating of key animal bones, the analysis of the microfauna and the sedimentological analysis have together enabled a picture to be developed of the changes in this section from the mid-Devensian to Late Glacial and Holocene
Correlation between Ventromedial Prefrontal Cortex Activation to Food Aromas and Cue-driven Eating: An fMRI Study
Food aromas are signals associated with both food's availability and pleasure. Previous research from this laboratory has shown that food aromas under fasting conditions evoke robust activation of medial prefrontal brain regions thought to reflect reward value (Bragulat, et al. 2010). In the current study, eighteen women (eleven normal-weight and seven obese) underwent a two-day imaging study (one after being fed, one while fasting). All were imaged on a 3T Siemens Trio-Tim scanner while sniffing two food (F; pasta and beef) odors, one non-food (NF; Douglas fir) odor, and an odorless control (CO). Prior to imaging, participants rated hunger and perceived odor qualities, and completed the Dutch Eating Behavior Questionnaire (DEBQ) to assess āExternalityā (the extent to which eating is driven by external food cues). Across all participants, both food and non-food odors (compared to CO) elicited large blood oxygenation level dependent (BOLD) responses in olfactory and reward-related areas, including the medial prefrontal and anterior cingulate cortex, bilateral orbitofrontal cortex, and bilateral piriform cortex, amygdala, and hippocampus. However, food odors produced greater activation of medial prefrontal cortex, left lateral orbitofrontal cortex and inferior insula than non-food odors. Moreover, there was a significant correlation between the [F > CO] BOLD response in ventromedial prefrontal cortex and āExternalityā sub-scale scores of the DEBQ, but only under the fed condition; no such correlation was present with the [NF > CO] response. This suggests that in those with high Externality, ventromedial prefrontal cortex may inappropriately valuate external food cues in the absence of internal hunger
Universal trapping scaling on the unstable manifold for a collisionless electrostatic mode
An amplitude equation for an unstable mode in a collisionless plasma is
derived from the dynamics on the two-dimensional unstable manifold of the
equilibrium. The mode amplitude decouples from the phase due to the
spatial homogeneity of the equilibrium, and the resulting one-dimensional
dynamics is analyzed using an expansion in . As the linear growth rate
vanishes, the expansion coefficients diverge; a rescaling
of the mode amplitude absorbs these
singularities and reveals that the mode electric field exhibits trapping
scaling as . The dynamics for
depends only on the phase where is the derivative of the dielectric as
.Comment: 11 pages (Latex/RevTex), 2 figures available in hard copy from the
Author ([email protected]); paper accepted by Physical Review
Letter
The pharmacokinetics of continuous subcutaneous levodopa/carbidopa infusion: Findings from the ND0612 clinical development program
BACKGROUND: While treatment with levodopa remains the cornerstone of Parkinson\u27s disease (PD) management, chronic oral therapy is often associated with the development of motor complications, that correlate to fluctuating levodopa plasma concentrations, limiting its clinical utility. Continuous infusion is considered to be the optimal delivery route for treating PD patients with motor fluctuations, but current infusion systems require invasive surgery. Subcutaneous infusion of (SC) levodopa has the potential to provide a better tolerated and more convenient route of continuous levodopa delivery. ND0612 is in development as a combination product providing continuous levodopa/carbidopa via a minimally invasive, subcutaneous delivery system for PD patients experiencing motor response fluctuations. We present pharmacokinetic results from a series of studies that analyzed plasma concentrations after SC levodopa delivery with ND0612 to inform the clinical development program.
METHODS: We performed a series of six Phase I and II studies to characterize the pharmacokinetics of levodopa and carbidopa derived from ND0612 infusion with/without adjunct oral therapy of the same ingredients. These studies were conducted in healthy volunteers and in PD patients experiencing motor response fluctuations while on their current levodopa therapy regimen.
RESULTS: Taken together, the results demonstrate dose-proportionality dependent on rate of subcutaneous levodopa infusion leading to stable and sustained plasma concentrations of levodopa. Subcutaneous infusion of ND0612 administered with oral levodopa/carbidopa maintained near-constant, therapeutic levodopa plasma concentrations, thereby avoiding the troughs in levodopa plasma concentrations that are associated with OFF time in PD. The data generated in this series of studies also confirmed that a levodopa/carbidopa dose ratio of 8:1 would be the most reasonable choice for ND0612 development.
CONCLUSIONS: This series of clinical pharmacokinetic studies have demonstrated that ND0612, administered continuously with a levodopa concentration of 60 mg/ml combined with carbidopa 7.5 mg/ml, and complemented with oral levodopa/carbidopa, is suitable for 24 h continuous administration in patients with PD. The stable plasma concentrations of levodopa achieved predict utility of ND0612 as a parenteral formulation for achieving clinically useful delivery of levodopa for PD patients
- ā¦