12,253 research outputs found

    New species of New World Tambiniini from palms: (Hemiptera: Fulgoroidea, Tropiduchidae)

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    Eine neue Gattung und Art, Diambon remanei nov. gen. nov. spec. aus Trinidad sowie zwei neue Arten der Gattung Athestia Melichar, 1914, A. excelsa nov. spec. aus Mexico und A. aschei nov. spec. aus Argentinien werden beschrieben. Biruga Fennah, 1944 wird mit ihrer Typusart B. chapada wieder errichtet. Die Gattung Athestia wird wiederbeschrieben. Ein Schlüssel der Tambiniini der Neuen Welt wird präsentiert. Alle neu beschriebenen Arten wurden von Palmen gesammelt.One new genus and species, Diambon remanei nov gen. nov. spec. from Trinidad and two new species of Athestia Melichar, 1914, A. excelsa nov. spec. from Mexico and A. aschei nov. spec. from Argentina, are described and illustrated. Biruga  Fennah, 1944 is resurrected with its type-species B. chapadae. The genus Athestia is redescribed, and the genera and species of New World Tambiniini are keyed. All of the new species were collected from palms

    Reasonable responses versus proportionality in employee dismissal cases: A comparison between the Employment Rights Act 1996, s 98(4) and the Equality Act 2010, s 13(2), s 15(1)(b), and s 19(2)(d).

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    What, if any, are the differences between a dismissal that is reasonable and one that is a proportionate means of achieving a legitimate aim? That is the question at the centre of this dissertation. To answer it we start by placing both legal tests within the overall context of statute, then assess and analyse both separately. From that point the two can be fully compared. The structure of this dissertation is thus as follows: Chapter one outlines statutory provisions regulating dismissal from employment in both the Employment Rights Act 1996 (ERA) and Equality Act 2010 (EqA). It identifies the key role of section 98(4) of the ERA in deciding unfair dismissal claims; and the likewise key roles of sections 13(2), 15(1)(b), and 19(2)(d) of the EqA in deciding some categories of discrimination claim. Chapter two examines the application of ERA s 98(4) in depth to identify its interpretation, its impact on claimants and employers, and the likelihood of future legal developments in this area. Chapter three carries out a similar exercise for sections 13(2), 15(1)(b), and 19(2)(d) of the EqA. Having identified the central concepts of reasonable responses and proportionality, chapter four compares them directly. It focuses particularly on dual claim situations where both tests are necessarily applied side by side to the same facts. Overall conclusions are made about both differences and similarities found. It is argued that the relationship between reasonableness and proportionality in cases of employee dismissal is not fully settled within case law, and further clarification will likely be necessary in the future. Such clarification could go to the heart of distinctions between unfair dismissal and discrimination in UK law

    Dynamics of the Lyman alpha and C IV emitting gas in 3C 273

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    In this paper we study the variability properties of the Lyman alpha and C IV emission lines in 3C273 using archival IUE observations. Our data show for the first time the existence of variability on time scales of several years. We study the spatial distribution and the velocity field of the emitting gas by performing detailed analyses on the line variability using correlations, 1D and 2D response functions, and principal component analysis. In both lines we find evidence for two components, one which has the dynamic properties of gas in Keplerian motion around a black hole with a mass of the order of 10^9 Mo, and one which is characterized by high, blue-shifted velocities at large lag. There is no indication of the presence of optically thick emission medium neither in the Lya, nor in the Civ response functions. The component characterized by blue-shifted velocities, which is comparatively much stronger in Civ than in Lya, is more or less compatible with being the result of gas falling towards the central black hole with free-fall acceleration. We propose however that the line emission at high, blue-shifted velocities is better explained in terms of entrainment of gas clouds by the jet. This gas is therefore probably collisionally excited as a result of heating due to the intense infrared radiation from the jet, which would explain the strength of this component in Civ relative to Lya. This phenomenon might be a signature of disk-jet interaction.Comment: 16 pages, 10 figures. Accepted for publication in ApJ. Uses aaste

    Spectral Properties From Lyman-alpha to H-alpha For An Essentially Complete Sample of Quasars I: Data

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    We have obtained quasi-simultaneous ultraviolet-optical spectra for 22 out of 23 quasars in the complete PG-X-ray sample with redshift, z<0.4, and M_B<-23. The spectra cover rest-frame wavelengths from at least Lyman-alpha to H-alpha. Here we provide a detailed description of the data, including careful spectrophotometry and redshift determination. We also present direct measurements of the continua, strong emission lines and features, including Lyman-alpha, SiIV+OIV], CIV, CIII], SiIII], MgII, H-beta, [OIII], He5876+NaI5890,5896, H-alpha, and blended iron emission in the UV and optical. The widths, asymmetries and velocity shifts of profiles of strong emission lines show that CIV and Lyman-alpha are very different from H-beta and H-alpha. This suggests that the motion of the broad line region is related to the ionization structure, but the data appears not agree with the radially stratified ionization structure supported by reverberation mapping studies, and therefore suggest that outflows contribute additional velocity components to the broad emission line profiles.Comment: 42 pages, 10 figures, 13 tables. Accepted by AJ. Supplemental figures not included. Full version available at http://physics.uwyo.edu/~shang/pgxpaper/ShangPaper.pd

    Exact zero-point energy shift in the e⊗(n E)e\otimes (n~E), t⊗(n H)t\otimes (n~H) many modes dynamic Jahn-Teller systems at strong coupling

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    We find the exact semiclassical (strong coupling) zero-point energy shifts applicable to the e⊗(nE)e\otimes (n E) and t⊗(nH)t\otimes (n H) dynamic Jahn-Teller problems, for an arbitrary number nn of discrete vibrational modes simultaneously coupled to one single electronic level. We also obtain an analytical formula for the frequency of the resulting normal modes, which has an attractive and apparently general Slater-Koster form. The limits of validity of this approach are assessed by comparison with O'Brien's previous effective-mode approach, and with accurate numerical diagonalizations. Numerical values obtained for t⊗(nH)t\otimes (n H) with n=8n =8 and coupling constants appropriate to C60−_{60}^- are used for this purpose, and are discussed in the context of fullerene.Comment: 20 pages, 4 ps figure

    Unsolicited written narratives as a methodological genre in terminal illness: challenges and limitations

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    Stories about illness have proven invaluable in helping health professionals understand illness experiences. Such narratives have traditionally been solicited by researchers through interviews and the collection of personal writings, including diaries. These approaches are, however, researcher driven; the impetus for the creation of the story comes from the researcher and not the narrator. In recent years there has been exponential growth in illness narratives created by individuals, of their own volition, and made available for others to read in print or as Internet accounts. We sought to determine whether it was possible to identify such material for use as research data to explore the subject of living with the terminal illness amyotrophic lateral sclerosis/motor neuron disease—the contention being that these accounts are narrator driven and therefore focus on issues of greatest importance to the affected person. We encountered and sought to overcome a number of methodological and ethical challenges, which is our focus here

    The Extent and Cause of the Pre-White Dwarf Instability Strip

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    One of the least understood aspects of white dwarf evolution is the process by which they are formed. We are aided, however, by the fact that many H- and He-deficient pre-white dwarfs (PWDs) are multiperiodic g-mode pulsators. Pulsations in PWDs provide a unique opportunity to probe their interiors, which are otherwise inaccesible to direct observation. Until now, however, the nature of the pulsation mechanism, the precise boundaries of the instability strip, and the mass distribution of the PWDs were complete mysteries. These problems must be addressed before we can apply knowledge of pulsating PWDs to improve understanding of white dwarf formation. This paper lays the groundwork for future theoretical investigations of these stars. In recent years, Whole Earth Telescope observations led to determination of mass and luminosity for the majority of the (non-central star) PWD pulsators. With these observations, we identify the common properties and trends PWDs exhibit as a class. We find that pulsators of low mass have higher luminosity, suggesting the range of instability is highly mass-dependent. The observed trend of decreasing periods with decreasing luminosity matches a decrease in the maximum (standing-wave) g-mode period across the instability strip. We show that the red edge can be caused by the lengthening of the driving timescale beyond the maximum sustainable period. This result is general for ionization-based driving mechanisms, and it explains the mass-dependence of the red edge. The observed form of the mass-dependence provides a vital starting point for future theoretical investigations of the driving mechanism. We also show that the blue edge probably remains undetected because of selection effects arising from rapid evolution.Comment: 40 pages, 6 figures, accepted by ApJ Oct 27, 199

    Soft OR and practice : the contribution of the founders of Operation Research

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    This paper explores the work of some 43 founders of operations research. In particular, it considers the links between soft operations research (OR) and these founders. Several of the founders were direct influencers of the soft OR proponents, whereas others related to the context, process, and content of soft OR. Coupled with the deductive and inductive reasoning approaches of soft OR, it is argued that soft OR is a legitimate branch of OR. The paper also focuses on the embeddedness of the founders, and the soft OR proponents, in practice and argues that, for academics, engagement with practice has been and will continue to be an important driver for the health and development of operations research

    Optimal search strategies for hidden targets

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    What is the fastest way of finding a randomly hidden target? This question of general relevance is of vital importance for foraging animals. Experimental observations reveal that the search behaviour of foragers is generally intermittent: active search phases randomly alternate with phases of fast ballistic motion. In this letter, we study the efficiency of this type of two states search strategies, by calculating analytically the mean first passage time at the target. We model the perception mecanism involved in the active search phase by a diffusive process. In this framework, we show that the search strategy is optimal when the average duration of "motion phases" varies like the power either 3/5 or 2/3 of the average duration of "search phases", depending on the regime. This scaling accounts for experimental data over a wide range of species, which suggests that the kinetics of search trajectories is a determining factor optimized by foragers and that the perception activity is adequately described by a diffusion process.Comment: 4 pages, 5 figures. to appear in Phys. Rev. Let
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