532 research outputs found
Tutorials for software : a comparison of the Appleworks software tutorial with pre-entered data and an experimental tutorial with user entered data
The attention directed toward computer software research has been sparse which is quite evident in particular facets such as learning methods, specifically towards tutorials. Some authors have identified various important issues which include cognitive factors, reduction of presentation of superfluous information, and the importance of interaction with software and hardware. The present . study examined two tutorials which were similar except in their level of required user behaviors. Tutorial A required only user manipulation of disk stored data. Tutorial B required the user to enter the data into the computer, design the screen format, and then to manipulate it. It was predicted that the extra task of entering data and designing the screen format would provoke more positive scores for Tutorial B as measured by two independent questionnaires, would require fewer requests for assistance than for those using Tutorial A, and require a comparative duration period to complete. The results obtained supported all hypotheses except for the duration period which took longer for Tutorial B. The implication is that there should be development of improved Tutorial options utilizing research based methods such as these presented
New representation of water activity based on a single solute specific constant to parameterize the hygroscopic growth of aerosols in atmospheric models
Water activity is a key factor in aerosol thermodynamics and hygroscopic growth. We introduce a new representation of water activity (<i>a</i><sub>w</sub>), which is empirically related to the solute molality (&mu;<sub>s</sub>) through a single solute specific constant, &nu;<sub><i>i</i></sub>. Our approach is widely applicable, considers the Kelvin effect and covers ideal solutions at high relative humidity (RH), including cloud condensation nuclei (CCN) activation. It also encompasses concentrated solutions with high ionic strength at low RH such as the relative humidity of deliquescence (RHD). The constant &nu;<sub><i>i</i></sub> can thus be used to parameterize the aerosol hygroscopic growth over a wide range of particle sizes, from nanometer nucleation mode to micrometer coarse mode particles. In contrast to other <i>a</i><sub>w</sub>-representations, our &nu;<sub><i>i</i></sub> factor corrects the solute molality both linearly and in exponent form <i>x · a<sup>x</sup></i>. We present four representations of our basic <i>a</i><sub>w</sub>-parameterization at different levels of complexity for different <i>a</i><sub>w</sub>-ranges, e.g. up to 0.95, 0.98 or 1. &nu;<sub><i>i</i></sub> is constant over the selected <i>a</i><sub>w</sub>-range, and in its most comprehensive form, the parameterization describes the entire <i>a</i><sub>w</sub> range (0–1). In this work we focus on single solute solutions. &nu;<sub><i>i</i></sub> can be pre-determined with a root-finding method from our water activity representation using an <i>a</i><sub>w</sub>&minus;&mu;<sub>s</sub> data pair, e.g. at solute saturation using RHD and solubility measurements. Our <i>a</i><sub>w</sub> and supersaturation (Köhler-theory) results compare well with the thermodynamic reference model E-AIM for the key compounds NaCl and (NH<sub>4</sub>)<sub>2</sub>SO<sub>4</sub> relevant for CCN modeling and calibration studies. Envisaged applications include regional and global atmospheric chemistry and climate modeling
Technical Report Scintigraphic Evaluation of Bone Formation in Göttingen Minipigs
In experiments and processes requiring the application of nuclear tracers in large animals, statutory provisions and safety standards as well as a variety of techniques have to be regarded and employed. In order to sufficiently analyze questions pertaining to osseointegration as well as the possibility of ectopic bone formation in Göttingen minipigs, we decided to use scintigraphic examinations using 99mTc-HDP (Technetium - hydroxymethane diphosphonate). In this study, metallic implants coated in different forms with rhBMP-2 (recombinant human bone morphogenetic protein-2) were surgically introduced into the pigs’ femora. A total of 26 adult female minipigs (Ellegard, Dalmose, Denmark) averaging 40 months in age were post-surgically evaluated through the application of a radionuclide and its subsequent distribution using a scintillation camera. Each animal received approximately 10 MBq/kg BW (mega Becquerel per kilogram bodyweight). This paper describes the procedures of anaesthesia, the quite challenging transvaginal- urethral catheterization, the application of a catheter in the jugular vein, the radionuclide injection and the disposal of the sacrificed animals under statutory provisions and safety standards. The technical report reveals that the scintigraphic evaluation in large animal experiments is a practicable – yet sophisticated – method of examination and also strives to encourage further research groups to implement this elegant procedure.
Geospatial analysis and living urban geometry
This essay outlines how to incorporate morphological rules within the exigencies of our technological age. We propose using the current evolution of GIS (Geographical Information Systems) technologies beyond their original representational domain, towards predictive and dynamic spatial models that help in constructing the new discipline of "urban seeding". We condemn the high-rise tower block as an unsuitable typology for a living city, and propose to re-establish human-scale urban fabric that resembles the traditional city. Pedestrian presence, density, and movement all reveal that open space between modernist buildings is not urban at all, but neither is the open space found in today's sprawling suburbs. True urban space contains and encourages pedestrian interactions, and has to be designed and built according to specific rules. The opposition between traditional self-organized versus modernist planned cities challenges the very core of the urban planning discipline. Planning has to be re-framed from being a tool creating a fixed future to become a visionary adaptive tool of dynamic states in evolution
Uma Metodologia para o Desenvolvimento de Ontologias
Ontologias são um importante meio de representar, formalizar e compartilhar conhecimento. No contexto da Engenharia de Ontologias, várias metodologias de desenvolvimento são propostas, cada qual com suas características em relação ao ciclo de vida de ontologias. Por conseguinte, não há uma metodologia estabelecida como padrão para o propósito geral de desenvolvimento de ontologias. Por isso, na literatura acadêmica enfatiza-se a combinação de metodologias. Mediante o estudo de algumas metodologias, atentando as características de simplicidade, expressividade e funcionalidade, é abstraído um conjunto de elementos para o desenvolvimento de ontologias. Como resultado, tem-se uma nova metodologia, a qual compreende as atividades, as tarefas e a sugestão de ferramentas em um processo de desenvolvimento de ontologias, sendo que tal metodologia foi validada em pesquisas exploratórias e/ou aplicadas
Billiard Systems in Three Dimensions: The Boundary Integral Equation and the Trace Formula
We derive semiclassical contributions of periodic orbits from a boundary
integral equation for three-dimensional billiard systems. We use an iterative
method that keeps track of the composition of the stability matrix and the
Maslov index as an orbit is traversed. Results are given for isolated periodic
orbits and rotationally invariant families of periodic orbits in axially
symmetric billiard systems. A practical method for determining the stability
matrix and the Maslov index is described.Comment: LaTeX, 19 page
Proteomic and transcriptomic changes in hibernating grizzly bears reveal metabolic and signaling pathways that protect against muscle atrophy
Muscle atrophy is a physiological response to disuse and malnutrition, but hibernating bears are largely resistant to this phenomenon. Unlike other mammals, they efficiently reabsorb amino acids from urine, periodically activate muscle contraction, and their adipocytes differentially responds to insulin. The contribution of myocytes to the reduced atrophy remains largely unknown. Here we show how metabolism and atrophy signaling are regulated in skeletal muscle of hibernating grizzly bear. Metabolic modeling of proteomic changes suggests an autonomous increase of non-essential amino acids (NEAA) in muscle and treatment of differentiated myoblasts with NEAA is sufficient to induce hypertrophy. Our comparison of gene expression in hibernation versus muscle atrophy identified several genes differentially regulated during hibernation, including Pdk4 and Serpinf1. Their trophic effects extend to myoblasts from non-hibernating species (including C. elegans), as documented by a knockdown approach. Together, these changes reflect evolutionary favored adaptations that, once translated to the clinics, could help improve atrophy treatment
Definition of the σW regulon of Bacillus subtilis in the absence of stress
Bacteria employ extracytoplasmic function (ECF) sigma factors for their responses to environmental stresses. Despite intensive research, the molecular dissection of ECF sigma factor regulons has remained a major challenge due to overlaps in the ECF sigma factor-regulated genes and the stimuli that activate the different ECF sigma factors. Here we have employed tiling arrays to single out the ECF σW regulon of the Gram-positive bacterium Bacillus subtilis from the overlapping ECF σX, σY, and σM regulons. For this purpose, we profiled the transcriptome of a B. subtilis sigW mutant under non-stress conditions to select candidate genes that are strictly σW-regulated. Under these conditions, σW exhibits a basal level of activity. Subsequently, we verified the σW-dependency of candidate genes by comparing their transcript profiles to transcriptome data obtained with the parental B. subtilis strain 168 grown under 104 different conditions, including relevant stress conditions, such as salt shock. In addition, we investigated the transcriptomes of rasP or prsW mutant strains that lack the proteases involved in the degradation of the σW anti-sigma factor RsiW and subsequent activation of the σW-regulon. Taken together, our studies identify 89 genes as being strictly σW-regulated, including several genes for non-coding RNAs. The effects of rasP or prsW mutations on the expression of σW-dependent genes were relatively mild, which implies that σW-dependent transcription under non-stress conditions is not strictly related to RasP and PrsW. Lastly, we show that the pleiotropic phenotype of rasP mutant cells, which have defects in competence development, protein secretion and membrane protein production, is not mirrored in the transcript profile of these cells. This implies that RasP is not only important for transcriptional regulation via σW, but that this membrane protease also exerts other important post-transcriptional regulatory functions
The atmospheric chemistry general circulation model ECHAM5/MESSy1: consistent simulation of ozone from the surface to the mesosphere
International audienceThe new Modular Earth Submodel System (MESSy) describes atmospheric chemistry and meteorological processes in a modular framework, following strict coding standards. It has been coupled to the ECHAM5 general circulation model, which has been slightly modified for this purpose. A 90-layer model version up to 0.01 hPa was used at T42 resolution (~2.8 latitude and longitude) to simulate the lower and middle atmosphere. The model meteorology has been tested to check the influence of the changes to ECHAM5 and the radiation interactions with the new representation of atmospheric composition. A Newtonian relaxation technique was applied in the tropospheric part of the domain to weakly nudge the model towards the analysed meteorology during the period 1998?2005. It is shown that the tropospheric wave forcing of the stratosphere in the model suffices to reproduce the Quasi-Biennial Oscillation and major stratospheric warming events leading e.g. to the vortex split over Antarctica in 2002. Characteristic features such as dehydration and denitrification caused by the sedimentation of polar stratospheric cloud particles and ozone depletion during winter and spring are simulated accurately, although ozone loss in the lower polar stratosphere is slightly underestimated. The model realistically simulates stratosphere-troposphere exchange processes as indicated by comparisons with satellite and in situ measurements. The evaluation of tropospheric chemistry presented here focuses on the distributions of ozone, hydroxyl radicals, carbon monoxide and reactive nitrogen compounds. In spite of minor shortcomings, mostly related to the relatively coarse T42 resolution and the neglect of interannual changes in biomass burning emissions, the main characteristics of the trace gas distributions are generally reproduced well. The MESSy submodels and the ECHAM5/MESSy1 model output are available through the internet on request
A case study for the formation of stanene on a metal surface
The discovery and realization of graphene as an ideal two-dimensional (2D) material has triggered extensive efforts to create similar 2D materials with exciting spin-dependent properties. Here, we report on a novel Sn 2D superstructure on Au(111) that shows similarities and differences to the expected electronic features of ideal stanene. Using spin- and angle-resolved photoemission spectroscopy, we find that a particular Sn/Au superstructure reveals a linearly dispersing band centered at the Γ-point and below the Fermi level with antiparallel spin polarization and a Fermi velocity of vF ≈ 1×106 m/s, the same value as for graphene. We attribute the origin of the band structure to the hybridization between the Sn and the Au orbitals at the 2D Sn-Au interface. Considering that free-standing stanene simply cannot exist, our investigated structure is an important step towards the search of useful stanene-like overstructures for future technological applications
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