9,850 research outputs found
Abundance of small individuals influences the effectiveness of processing techniques for deep-sea nematodes
Nematodes are the most abundant metazoans of deep-sea benthic communities, but knowledge of their distribution is limited relative to larger organisms. Whilst some aspects of nematode processing techniques, such as extraction, have been extensively studied, other key elements have attracted little attention. We compared the effect of (1) mesh size (63, 45, and 32 Ī¼m) on estimates of nematode abundance, biomass, and body size, and (2) microscope magnification (50 and 100Ć) on estimates of nematode abundance at bathyal sites (250-3100 m water depth) on the Challenger Plateau and Chatham Rise, south-west Pacific Ocean. Variation in the effectiveness of these techniques was assessed in relation to nematode body size and environmental parameters (water depth, sediment organic matter content, %silt/clay, and chloroplastic pigments). The 63-Ī¼m mesh retained a relatively low proportion of total nematode abundance (mean Ā±SD = 55 Ā±9%), but most of nematode biomass (90 Ā± 4%). The proportion of nematode abundance retained on the 45-Ī¼m mesh in surface (0-1 cm) and subsurface (1-5 cm) sediment was significantly correlated (P < 0.01) with %silt/clay (RĀ² = 0.39) and chloroplastic pigments (RĀ² = 0.29), respectively. Variation in median nematode body weight showed similar trends, but relationships between mean nematode body weight and environmental parameters were either relatively weak (subsurface sediment) or not significant (surface sediment). Using a low magnification led to significantly lower (on average by 43%) nematode abundance estimates relative to high magnification (P < 0.001), and the magnitude of this difference was significantly correlated (P < 0.05) with total nematode abundance (RĀ²p = 0.53) and the number of small (ā¤ 250 Ī¼m length) individuals (RĀ²p = 0.05). Our results suggest that organic matter input and sediment characteristics influence the abundance of small nematodes in bathyal communities. The abundance of small individuals can, in turn, influence abundance estimates obtained using different mesh sizes and microscope magnifications
Facet-dependent electron trapping in TiO2 nanocrystals
The trapping of electrons at surfaces of nanocrystalline titanium dioxide can be decisive in controlling performance for diverse applications in photocatalysis, energy storage, and solar energy generation. Here, we employ first-principles calculations to elucidate the factors which influence electron trapping for all low index surfaces of rutile TiO2. We show that different surface orientations exhibit markedly different electron affinities: some preferring to trap electrons with others repelling electrons. We demonstrate that local variations in trapping energy are linked to variations in electrostatic potential and ion coordination providing atomistic insight into this effect. The equilibrium nanocrystal morphology exposes both electron-trapping and electron-repelling facets and therefore is predicted to possess highly anisotropic electron-trapping properties. We discuss how knowledge of surface-specific trapping properties can be utilized to design a number of nanocrystal morphologies which may offer improved performance for applications. (Figure Presented)
Legal Research: Techniques and Ideas
This paper was prepared for the conference of New Zealand University Law Teachers held at Massey University in November 1977. Though the authors here make no special claims originality or great insight, the many ideas developed, particularly when taken together with Professor Campbell's trenchant piece on legal writing and John Thomas' more recent article on legal education (both reprinted in this volume), which stresses the relationship between teaching and research, will be of value to the increasing numbers of lawyers engaged in research
Parallel computations and control of adaptive structures
The equations of motion for structures with adaptive elements for vibration control are presented for parallel computations to be used as a software package for real-time control of flexible space structures. A brief introduction of the state-of-the-art parallel computational capability is also presented. Time marching strategies are developed for an effective use of massive parallel mapping, partitioning, and the necessary arithmetic operations. An example is offered for the simulation of control-structure interaction on a parallel computer and the impact of the approach presented for applications in other disciplines than aerospace industry is assessed
Direct Visualization of Laser-Driven Focusing Shock Waves
Cylindrically or spherically focusing shock waves have been of keen interest
for the past several decades. In addition to fundamental study of materials
under extreme conditions, cavitation, and sonoluminescence, focusing shock
waves enable myriad applications including hypervelocity launchers, synthesis
of new materials, production of high-temperature and high-density plasma
fields, and a variety of medical therapies. Applications in controlled
thermonuclear fusion and in the study of the conditions reached in laser fusion
are also of current interest. Here we report on a method for direct real-time
visualization and measurement of laser-driven shock generation, propagation,
and 2D focusing in a sample. The 2D focusing of the shock front is the
consequence of spatial shaping of the laser shock generation pulse into a ring
pattern. A substantial increase of the pressure at the convergence of the
acoustic shock front is observed experimentally and simulated numerically.
Single-shot acquisitions using a streak camera reveal that at the convergence
of the shock wave in liquid water the supersonic speed reaches Mach 6,
corresponding to the multiple gigapascal pressure range 30 GPa
The discovery of 2.78 hour periodic modulation of the X-ray flux from globular cluster source Bo 158 in M31
We report the discovery of periodic intensity dips in the X-ray source XMMU
J004314.1+410724, in the globular cluster Bo158 in M31. The X-ray flux was
modulated by ~83% at a period of 2.78 hr (10017 s) in an XMM-Newton observation
taken 2002 Jan 6-7. The X-ray intensity dips show no energy dependence. We
detected weaker dips with the same period in observations taken 2000 June 25
(XMM-Newton) and 1991 June 26 (ROSAT/PSPC). The amplitude of the modulation has
been found to be anticorrelated with source X-ray flux: it becomes lower when
the source intensity rises. The energy spectrum of Bo158 was stable from
observation to observation, with a characteristic cutoff at ~4-6 keV. The
photo-electric absorption was consistent with the Galactic foreground value. No
significant spectral changes were seen in the course of the dips. If the 2.78
hr cycle is the binary period of Bo158 the system is highly compact, with a
binary separation of ~10e11 cm. The association of the source with a globular
cluster, together with spectral parameters consistent with Galactic neutron
star sources, suggests that X-rays are emitted by an accreting neutron star.
The properties of Bo 158 are somewhat reminiscent of the Galactic X-ray sources
exhibiting a dip-like modulations. We discuss two possible mechanisms
explaining the energy-independent modulation observed in Bo 158: i) the
obscuration of the central source by highly ionized material that scatters
X-rays out of the line of sight; ii) partial covering of an extended source by
an opaque absorber which occults varying fractions of the source.Comment: 10 pages, 4 figures, ApJ, submitted, uses emulateapj styl
The role of place branding and image in the development of sectoral clusters: the case of Dubai
This paper contextualizes how place branding and image influence the development of Dubaiās key sectoral clusters, including the key determinants of growth and success under the impression of Porterās cluster theory. The approach is exploratory and of a qualitative inductive nature. Data was collected through conducting 21 semi-structured interviews with Dubaiās marketing/communication managers and stakeholders. Findings suggest that Dubaiās traditional clusters, namely, trading, tourism and logistics that have strong place branding and image show strong signs of success owing to Dubaiās geographical location (i.e., physical conditions). Among the new clusters, the financial sector is also benefitting from place branding. The results suggest that the success of traditional clusters have a positive spill over effect on the new clusters, in particular on construction and real estate. For policy makers it is worth to note that the recent success of the financial services cluster in Dubai will have positive impact on both, the traditional as well new clusters. The marketing and brand communication managers must consider the correlation and interplay of strength of activities amongst trading, tourism and logistics clusters and its implication while undertaking place branding for clients in their sector
Retest reliability of balance and mobility measurements in people with mild to moderate Alzheimerās disease
ABSTRACTBackground: To interpret changes of balance and mobility in people with Alzheimer's disease (AD), we require measures of balance and mobility that have demonstrated reliability in this population. The aim of the study was to determine the safety, feasibility and retest reliability of clinical and forceplate balance and mobility measurements in people with AD.Methods: Relative and absolute reliabilities were examined in 14 older people with mild to moderate AD. Relative reliability was calculated using the intraclass correlation coefficient, two-way mixed model (ICC3,1). Absolute reliability was calculated using the standard error of measurement (SEM), the minimum detectable change (MDC) and the coefficient of variation (CV).Results: All measurements were clinically feasible and could be safely administered. ICC values were excellent and CVs were less than 11% in all clinical balance and mobility measures except the Timed Up & Go test with cognitive or manual task (ICC3,1= 0.5 and 0.7, and CV = 14% and 10%, respectively). Most balance and mobility measures tested on the Neurocomā¢ forceplate (modified Clinical Test of Sensory Interaction on Balance, Walk Across (step width, step length parameters), and Sit to Stand (rising index parameter)) had excellent relative reliability (ICC3,1ranging from 0.75 to 0.91). ICC values were fair to good for the other measures.Conclusions: Retest reliability of the balance and mobility measures used in this study ranged between fair to good, and good to excellent. Clinicians should consider retest reliability when deciding which balance and mobility measures are used to assess people with AD.</jats:p
Looking for the Charged Higgs Boson
This review article starts with a brief introduction to the charged Higgs
boson (H^\pm) in the Minimal Supersymmetric Standard Model (MSSM). It then
discusses the prospects of a relatively light H^\pm boson search via top quark
decay at Tevatron/LHC, and finally a heavy H^\pm boson search at LHC. The
viable channels for H^\pm search are identified in both the cases, with
particular emphasis on the H^\pm --> tau + nu decay channel. The effects of NLO
QCD correction in the SM as well as the MSSM are discussed briefly.Comment: 17 pages with 8 eps figures, Invited review, Reference adde
Numerical verification of universality for the Anderson transition
We analyze the scaling behavior of the higher Lyapunov exponents at the
Anderson transition. We estimate the critical exponent and verify its
universality and that of the critical conductance distribution for box,
Gaussian and Lorentzian distributions of the random potential
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