8,222 research outputs found
Does cognitive ability influence responses to the Warwick-Edinburgh Mental Well-Being Scale?
It has been suggested that how individuals respond to self-report items relies on cognitive processing. We hypothesized that an individual's level of cognitive ability may influence these processes such that, if there is a hierarchy of items within a particular questionnaire, as demonstrated by Mokken scaling, the strength of that hierarchy will vary according to cognitive ability. Using data on 8,643 men and women from the National Child Development Survey (1958 birth cohort; Power, & Elliott, 2006), we investigated, using Mokken scaling, whether the 14 items that make up the Warwick-Edinburgh Mental Well-Being Scale (Tennant et al., 2007)-completed when the participants were 50 years of age-form a hierarchy and whether that hierarchy varied according to cognitive ability at age 11 years. Among the sample as a whole, we found a moderately strong unidimensional hierarchy of items (Loevinger's coefficient [H] = 0.48). We split participants into 3 groups according to cognitive ability and analyzed the Mokken scaling properties of each group. Only the medium and high cognitive ability groups had acceptable (?0.3) invariant item ordering (assessed using the HT statistic). This pattern was also found when the 3 cognitive ability groups were assessed within men and women separately. Greater attention should be paid to the content validity of questionnaires to ensure they are applicable across the spectrum of mental ability
Understanding Heisenberg's 'Magical' Paper of July 1925: a New Look at the Calculational Details
In July 1925 Heisenberg published a paper [Z. Phys. 33, 879-893 (1925)] which
ended the period of `the Old Quantum Theory' and ushered in the new era of
Quantum Mechanics. This epoch-making paper is generally regarded as being
difficult to follow, perhaps partly because Heisenberg provided few clues as to
how he arrived at the results which he reported. Here we give details of
calculations of the type which, we suggest, Heisenberg may have performed. We
take as a specific example one of the anharmonic oscillator problems considered
by Heisenberg, and use our reconstruction of his approach to solve it up to
second order in perturbation theory. We emphasize that the results are
precisely those obtained in standard quantum mechanics, and suggest that some
discussion of the approach - based on the direct computation of transition
amplitudes - could usefully be included in undergraduate courses in quantum
mechanics.Comment: 24 pages, no figures, Latex, submitted to Am. J. Phy
Minimum Weight Flat Antichains of Subsets
Building on classical theorems of Sperner and Kruskal-Katona, we investigate
antichains in the Boolean lattice of all subsets of
, where is flat, meaning that it contains
sets of at most two consecutive sizes, say , where contains only -subsets,
while contains only -subsets. Moreover, we assume
consists of the first -subsets in squashed
(colexicographic) order, while consists of all -subsets
not contained in the subsets in . Given reals , we
say the weight of is
. We characterize the minimum
weight antichains for any given , and we do the
same when in addition is a maximal antichain. We can then derive
asymptotic results on both the minimum size and the minimum Lubell function
Simultaneous multiplane imaging with reverberation multiphoton microscopy
Multiphoton microscopy (MPM) has gained enormous popularity over the years for its capacity to provide high resolution images from deep within scattering samples1. However, MPM is generally based on single-point laser-focus scanning, which is intrinsically slow. While imaging speeds as fast as video rate have become routine for 2D planar imaging, such speeds have so far been unattainable for 3D volumetric imaging without severely compromising microscope performance. We demonstrate here 3D volumetric (multiplane) imaging at the same speed as 2D planar (single plane) imaging, with minimal compromise in performance. Specifically, multiple planes are acquired by near-instantaneous axial scanning while maintaining 3D micron-scale resolution. Our technique, called reverberation MPM, is well adapted for large-scale imaging in scattering media with low repetition-rate lasers, and can be implemented with conventional MPM as a simple add-on.Accepted manuscrip
A homoleptic phosphine adduct of Tl(I)
A homoleptic phosphine adduct of thallium(I) supported by a tris(phosphino)borate ligand has been isolated and structurally characterized
Current treatment of choice for chronic hepatitis C infection
More than three million Americans have chronic hepatitis C infection, and the disease remains one of the most common blood-borne infections in the US. Treatment is focused on the chronic form of the disease, because the acute one tends to be self-limiting. In this article, we review the recent literature regarding the most effective therapy against hepatitis C infection, to confirm the current treatment of choice for the disease. We conclude that combination therapy with pegylated interferon and ribavirin remains the initial treatment of choice. New research focusing on adjuvant therapies, such as protease and polymerase inhibitors, has yielded early data that appear to be promising
Development of a Compact Neutron Source based on Field Ionization Processes
The authors report on the use of carbon nanofiber nanoemitters to ionize
deuterium atoms for the generation of neutrons in a deuterium-deuterium
reaction in a preloaded target. Acceleration voltages in the range of 50-80 kV
are used. Field emission of electrons is investigated to characterize the
emitters. The experimental setup and sample preparation are described and first
data of neutron production are presented. Ongoing experiments to increase
neutron production yields by optimizing the field emitter geometry and surface
conditions are discussed.Comment: 4 pages, 5 figures; IVNC 201
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