1,024 research outputs found

    Broadening of Spectral Lines due to Dynamic Multiple Scattering and the Tully-Fisher Relation

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    The frequency shift of spectral lines is most often explained by the Doppler Effect in terms of relative motion, whereas the Doppler broadening of a particular line mainly depends on the absolute temperature. The Wolf effect on the other hand deals with the correlation induced spectral change and explains both the broadening and shift of the spectral lines. In this framework a relation between the width of the spectral line is related to the redshift z for the line and hence with the distance. For smaller values of z a relation similar to the Tully-Fisher relation can be obtained and for larger values of z a more general relation can be constructed. The derivation of this kind of relation based on dynamic multiple scattering theory may play a significant role in explaining the overall spectra of quasi stellar objects. We emphasize that this mechanism is not applicable for nearby galaxies, z≀1z \leq 1.Comment: 18 pages, 5 figures, revised Version has been submitted to Physical Review A. (2nd author's affiliation corrected

    New Computer System for Recognizing Micro- and Nano-Sized Objects in Semiconductors and Colloidal Solutions

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    In this paper it is describe a new approach developed for recognizing micro- and nano-sized objects and a method for quantitative analysis of these objects. For this purpose was developed the automated systems that can simplify and accelerate the process of nanoparticle tracks analysis under the microscope whereby engineers and scientists are able to recognize the structures of defects in semiconductor wafers, along with nanoparticles and other microscopic objects. This capability is important to both select appropriate crystals and also to apply the data to improve the production process

    Predicting university performance in psychology: the role of previous performance and discipline-specific knowledge

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    Recent initiatives to enhance retention and widen participation ensure it is crucial to understand the factors that predict students' performance during their undergraduate degree. The present research used Structural Equation Modeling (SEM) to test three separate models that examined the extent to which British Psychology students' A-level entry qualifications predicted: (1) their performance in years 1-3 of their Psychology degree, and (2) their overall degree performance. Students' overall A-level entry qualifications positively predicted performance during their first year and overall degree performance, but negatively predicted their performance during their third year. Additionally, and more specifically, students' A-level entry qualifications in Psychology positively predicted performance in the first year only. Such findings have implications for admissions tutors, as well as for students who have not studied Psychology before but who are considering applying to do so at university

    Towards eco-efficient lean production systems

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    Lean Production has proved itself a worthwhile production strategy in many distinct industries across all regions of the planet by achieving higher levels of production efficiency. Several authors identified that Lean inadvertently has had significant environmental gains. Such achievements are considered of special relevance in a global and highly competitive economy which is progressively both tied-up and driven by an environmental agenda. The main goal of the present study is to enlighten the contribution of Lean for achieving a better environmental performance of production systems and identify this as an emergent business model for supporting eco-efficiency

    Novel Methods for Determining Effective Interactions for the Nuclear Shell Model

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    The Contractor Renormalization (CORE) method is applied in combination with modern effective-theory techniques to the nuclear many-body problem. A one-dimensional--yet ``realistic''--nucleon-nucleon potential is introduced to test these novel ideas. It is found that the magnitude of ``model-space'' (CORE) corrections diminishes considerably when an effective potential that eliminates the hard-momentum components of the potential is first introduced. As a result, accurate predictions for the ground-state energy of the there-body system are made with relatively little computational effort when both techniques are used in a complementary fashion.Comment: 14 pages, 5 figures and 2 tabl

    Structural identifiability analyses of candidate models for in vitro Pitavastatin hepatic uptake

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    In this paper a review of the application of four different techniques (a version of the similarity transformation approach for autonomous uncontrolled systems, a non-differential input/output observable normal form approach, the characteristic set differential algebra and a recent algebraic input/output relationship approach) to determine the structural identifiability of certain in vitro nonlinear pharmacokinetic models is provided. The Organic Anion Transporting Polypeptide (OATP) substrate, Pitavastatin, is used as a probe on freshly isolated animal and human hepatocytes. Candidate pharmacokinetic non-linear compartmental models have been derived to characterise the uptake process of Pitavastatin. As a prerequisite to parameter estimation, structural identifiability analyses are performed to establish that all unknown parameters can be identified from the experimental observations available

    Magnetotransport properties of a polarization-doped three-dimensional electron slab

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    We present evidence of strong Shubnikov-de-Haas magnetoresistance oscillations in a polarization-doped degenerate three-dimensional electron slab in an Alx_{x}Ga1−x_{1-x}N semiconductor system. The degenerate free carriers are generated by a novel technique by grading a polar alloy semiconductor with spatially changing polarization. Analysis of the magnetotransport data enables us to extract an effective mass of m⋆=0.19m0m^{\star}=0.19 m_{0} and a quantum scattering time of τq=0.3ps\tau_{q}= 0.3 ps. Analysis of scattering processes helps us extract an alloy scattering parameter for the Alx_{x}Ga1−x_{1-x}N material system to be V0=1.8eVV_{0}=1.8eV

    English as the International Language of Research

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    The annual world output of research papers and scholarly ar ticles is large and increasing, and there is little doubt that English is the medium of publication for the majority of such papers. However, closer analyses of the available data reveal rather few papers from non- native speakers, especially from the Third World. This imbalance sug gests that English is only the International Language of Research in a receptive sense. It needs to become so in a productive sense as well if Third World investment in doctoral scholarship etc. is to remain justified. Unfortunately, the ESP profession has concentrated on undergraduate teaching programmes and rather neglected the teaching of Research English. However, there are now welcome signs of change, which may therefore aid a process of making English a truly international language rather than one over-restricted in terms of publication sources to the Northern Hemisphere.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68423/2/10.1177_003368828501600101.pd
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