1,101 research outputs found
Designing pseudocubic perovskites with enhanced nanoscale polarization
A crystal-chemical framework has been proposed for the design of pseudocubic perovskites with
nanoscale ferroelectric order, and its applicability has been demonstrated using a series of represen-
tative solid solutions that combined ferroelectric (K
0.5
Bi
0.5
TiO
3
, BaTiO
3
, and PbTiO
3
) and antifer-
roelectric (Nd-substituted BiFeO
3
) end members. The pseudocubic structures obtained in these
systems exhibited distortions that were coherent on a scale ranging from sub-nanometer to tens of
nanometers, but, in all cases, the macroscopic distortion remained unresolvable even if using high-
resolution X-ray powder diffraction. Different coherence lengths for the local atomic displacements
account for the distinctly different dielectric, ferroelectric, and electromechanical properties exhib-
ited by the samples. The guidelines identified provide a rationale for chemically tuning the coher-
ence length to obtain the desired functional response
Kaneohe Bay Sewage Diversion Experiment: Perspectives on Ecosystem Responses to Nutritional Perturbation
Kaneohe Bay, Hawaii, received increasing amounts of sewage
from the 1950s through 1977. Most sewage was diverted from the bay in 1977
and early 1978. This investigation, begun in January 1976 and continued
through August 1979, described the bay over that period, with particular
reference to the responses of the ecosystem to sewage diversion.
The sewage was a nutritional subsidy. All of the inorganic nitrogen and
most of the inorganic phosphorus introduced into the ecosystem were taken
up biologically before being advected from the bay. The major uptake was by
phytoplankton, and the internal water-column cycle between dissolved nutrients,
phytoplankton, zooplankton, microheterotrophs, and detritus supported
a rate of productivity far exceeding the rate of nutrient loading.
These water-column particles were partly washed out of the ecosystem and
partly sedimented and became available to the benthos. The primary benthic
response to nutrient loading was a large buildup of detritivorous heterotrophic
biomass. Cycling of nutrients among heterotrophs, autotrophs, detritus, and
inorganic nutrients was important.
With sewage diversion, the biomass of both plankton and benthos decreased
rapidly. Benthic biological composition has not yet returned to presewage
conditions, partly because some key organisms are long-lived and partly
because the bay substratum has been perturbed by both the sewage and other
human influences
Differential Impact of Serial Measurement of Nonplatelet Thromboxane Generation on Long-Term Outcome After Cardiac Surgery.
BACKGROUND: Systemic thromboxane generation, not suppressible by standard aspirin therapy and likely arising from nonplatelet sources, increases the risk of atherothrombosis and death in patients with cardiovascular disease. In the RIGOR (Reduction in Graft Occlusion Rates) study, greater nonplatelet thromboxane generation occurred early compared with late after coronary artery bypass graft surgery, although only the latter correlated with graft failure. We hypothesize that a similar differential association exists between nonplatelet thromboxane generation and long-term clinical outcome.
METHODS AND RESULTS: Five-year outcome data were analyzed for 290 RIGOR subjects taking aspirin with suppressed platelet thromboxane generation. Multivariable modeling was performed to define the relative predictive value of the urine thromboxane metabolite, 11-dehydrothromboxane B
CONCLUSIONS: Long-term nonplatelet thromboxane generation after coronary artery bypass graft surgery is a novel risk factor for 5-year adverse outcome, including death. In contrast, nonplatelet thromboxane generation in the early postoperative period appears to be driven predominantly by inflammation and did not independently predict long-term clinical outcome
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Profiling complex word usage in the speech of English preschool children: frequency patterns and transparency characteristics
This corpus-based study provides a baseline of complex word usage patterns in the spontaneous speech of English preschool children to ascertain the characteristics of their derivative vocabulary before literacy development affects language skills. Frequencies of suffixed derivatives produced by (N=243) children aged 2-5 and their caregivers were extracted for 58 suffix variants, yielding 558 types from the former and 1,364 from the latter. Between the youngest and oldest groups, 11 suffix categories increased significantly in type frequency, compared with 22 in the caregiver dataset. All derivative types were classified for transparency of meaning and simplicity of form on a 5-point analysability scale. Around 59% of both the child and caregiver derivative vocabulary sets were classified as transparent regardless of age, suggesting that the potential analysability of the preschool child’s input remains surprisingly invariant over time. The study provides baseline data for future studies on the development of morphological awareness in English-speaking schoolchildren
From policy to practice: exploring practitioners' perspectives on social enterprise policy claims
Criminal narrative experience: relating emotions to offence narrative roles during crime commission
A neglected area of research within criminality has been that of the experience of the offence for the offender. The present study investigates the emotions and narrative roles that are experienced by an offender while committing a broad range of crimes and proposes a model of Criminal Narrative Experience (CNE). Hypotheses were derived from the Circumplex of Emotions (Russell, 1997), Frye (1957), Narrative Theory (McAdams, 1988) and its link with Investigative Psychology (Canter, 1994). The analysis was based on 120 cases. Convicted for a variety of crimes, incarcerated criminals were interviewed and the data were subjected to Smallest Space Analysis (SSA). Four themes of Criminal Narrative Experience (CNE) were identified: Elated Hero, Calm Professional, Distressed Revenger and Depressed Victim in line with the recent theoretical framework posited for Narrative Offence Roles (Youngs & Canter, 2012). The theoretical implications for understanding crime on the basis of the Criminal Narrative Experience (CNE) as well as practical implications are discussed
Cymantrene–Triazole "Click" Products: Structural Characterization and Electrochemical Properties
We report the first known examples of triazole-derivatized cymantrene complexes (η5-[4-substituted triazol-1-yl]cyclopentadienyl)tricarbonylmanganese(I), obtained via a “click” chemical synthesis, bearing a phenyl, 3-aminophenyl, or 4-aminophenyl moiety at the 4-position of the triazole ring. Structural characterization data using multinuclear NMR, UV–vis, ATR-IR, and mass spectrometric methods are provided, as well as crystallographic data for (η5-[4-phenyltriazol-1-yl]cyclopentadienyl)tricarbonylmanganese(I) and (η5-[4-(3-aminophenyl)triazol-1-yl]cyclopentadienyl)tricarbonylmanganese(I). Cyclic voltammetric characterization of the redox behavior of each of the three cymantrene–triazole complexes is presented together with digital simulations, in situ infrared spectroelectrochemistry, and DFT calculations to extract the associated kinetic and thermodynamic parameters. The trypanocidal activity of each cymantrene–triazole complex is also examined, and these complexes are found to be more active than cymantrene alone
Searching for the signatures of terrestial planets in solar analogs
We present a fully differential chemical abundance analysis using very
high-resolution (R >~ 85,000) and very high signal-to-noise (S/N~800 on
average) HARPS and UVES spectra of 7 solar twins and 95 solar analogs, 24 are
planet hosts and 71 are stars without detected planets. The whole sample of
solar analogs provide very accurate Galactic chemical evolution trends in the
metalliciy range -0.3<[Fe/H]<0.5. Solar twins with and without planets show
similar mean abundance ratios. We have also analysed a sub-sample of 28 solar
analogs, 14 planet hosts and 14 stars without known planets, with spectra at
S/N~850 on average, in the metallicity range 0.14<[Fe/H]<0.36 and find the same
abundance pattern for both samples of stars with and without planets. This
result does not depend on either the planet mass, from 7 Earth masses to 17.4
Jupiter masses, or the orbital period of the planets, from 3 to 4300 days. In
addition, we have derived the slope of the abundance ratios as a function of
the condensation temperature for each star and again find similar distributions
of the slopes for both stars with and without planets. In particular, the peaks
of these two distributions are placed at a similar value but with opposite sign
as that expected from a possible signature of terrestial planets. In
particular, two of the planetary systems in this sample, containing each of
them a Super-Earth like planet, show slope values very close to these peaks
which may suggest that these abundance patterns are not related to the presence
of terrestial planets.Comment: Accepted for publication in The Astrophysical Journa
Late Miocene to early Pliocene biofacies of Wanganui and Taranaki Basins, New Zealand: Applications to paleoenvironmental and sequence stratigraphic analysis
The Matemateaonga Formation is late Miocene to early Pliocene (upper Tongaporutuan to lower Opoitian New Zealand Stages) in age. The formation comprises chiefly shellbeds, siliciclastic sandstone, and siltstone units and to a lesser extent non-marine and shallow marine conglomerate and rare paralic facies. The Matemateaonga Formation accumulated chiefly in shelf paleoenvironments during basement onlap and progradation of a late Miocene to early Pliocene continental margin wedge in the Wanganui and Taranaki Basins. The formation is strongly cyclothemic, being characterised by recurrent vertically stacked facies successions, bounded by sequence boundaries. These facies accumulated in a range of shoreface to mid-outer shelf paleoenvironments during conditions of successively oscillating sea level. This sequential repetition of facies and the biofacies they enclose are the result of sixth-order glacio-eustatic cyclicity. Macrofaunal associations have been identified from statistical analysis of macrofossil occurrences collected from multiple sequences. Each association is restricted to particular lithofacies and stratal positions and shows a consistent order and/or position within the sequences. This pattern of temporal paleoecologic change appears to be the result of lateral, facies-related shifting of broad biofacies belts, or habitat-tracking, in response to fluctuations of relative sea level, sediment flux, and other associated paleoenvironmental variables. The associations also show strong similarity in terms of their generic composition to biofacies identified in younger sedimentary strata and the modern marine benthic environment in New Zealand
Lithium in the Intermediate-Age Open Cluster, NGC 3680
High-dispersion spectra centered on the Li 6708 A line have been obtained for
70 potential members of the open cluster NGC 3680, with an emphasis on stars in
the turnoff region. A measurable Li abundance has been derived for 53 stars, 39
of which have radial velocities and proper motions consistent with cluster
membership. After being transferred to common temperature and abundance scales,
previous Li estimates have been combined to generate a sample of 49 members, 40
of which bracket the cluster Li-dip. Spectroscopic elemental analysis of 8
giants and 5 turnoff stars produces [Fe/H] = -0.17 +/- 0.07 (sd) and -0.07 +/-
0.02 (sd), respectively. We also report measurements of Ca, Si and Ni which are
consistent with scaled-solar ratios within the errors. Adopting [Fe/H] = -0.08
(Sect. 3.6), Y^2 isochrone comparisons lead to an age of 1.75 +/- 0.10 Gyr and
an apparent modulus of (m-M) = 10.30 +/- 0.15 for the cluster, placing the
center of the Li-dip at 1.35 +/- 0.03 solar masses. Among the giants, 5 of 9
cluster members are now known to have measurable Li with A(Li) near 1.0. A
combined sample of dwarfs in the Hyades and Praesepe is used to delineate the
Li-dip profile at 0.7 Gyr and [Fe/H] = +0.15, establishing its center at 1.42
+/- 0.02 solar masses and noting the possible existence of secondary dip on its
red boundary. When evolved to the typical age of the clusters NGC 752, IC 4651
and NGC 3680, the Hyades/Praesepe Li-dip profile reproduces the observed
morphology of the combined Li-dip within the CMD's of the intermediate-age
clusters while implying a metallicity dependence for the central mass of the
Li-dip given by Mass = (1.38 +/-0.04) + (0.4 +/- 0.2)[Fe/H]. The implications
of the similarity of the Li-dichotomy among giants in NGC 752 and IC 4651 and
the disagreement with the pattern among NGC 3680 giants are discussed.Comment: Latex ms. is 56 pages, including 10 figures and 4 tables. Accepted
for the Astronomical Journa
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