36,034 research outputs found
Late Holocene mud sedimentation and diagenesis in the Firth of Thames: Bentonites in the making
No full textLate Holocene mud sedimentation in the southern Firth of Thames has been described from analysis of a number of shallow marine sediment cores. Three distinct lithofacies are distinguished on the basis of sediment texture and mineralogy. A laterally extensive greenish grey mud, typically bioturbated and massive, with sporadic uncorrelatable interbedded shell layers is termed the Firth of Thames mud facies. Nearer shore sediments are usually coarser and are subdivided into two facies: a siliciclastic sand facies (river mouth sand facies) comprising more prominent interbeds of sand in mud and associated with sedimentation at the mouth of the Waihou River; and a mixed terrigenous-carbonate gravel facies (delta fan gravel facies) associated with deposition on small delta fans adjacent to streams draining the Coromandel Range. The areal distribution of all three facies over the late Holocene has been controlled largely by northward progradation of the coastal Hauraki Lowland associated with the rapid sediment infilling of the Firth of Thames since sea level reached its present height 6500 y B.P. From seismic evidence the Holocene muds are up to 10m thick. The cores in this study penetrated only to 5.5m sub-bottom depth and yielded an oldest radiocarbon age of 5000 y B.P. The age data indicate an average rate of offshore vertical sediment accumulation of 1.5 mm/y.
Up to 15 km of progradation of the southern shoreline of the coastal Hauraki Lowland has occurred over the late Holocene at an average rate of up to 2.5 m/y, notably from 3500 y B.P to 1200 y B.P. Progradation is evidenced by the occurrence of coarsening-upward sequences in nearer shore cores of the Firth of Thames, as well as their changing faunal composition, particularly the upward increase in abundance of the foraminifer Ammonia beccarri, a good indicator of brackish water conditions, which suggests a gradual seaward encroachment of the freshwater influence of the Waihou River over the late Holocene. Basal muds which are similar in composition to marine sediments of the Firth of Thames are overlain by peat dated at 6025 y B.P in a peat core from Kopouatai Peat Bog, and suggest that marine conditions existed in this inland region of the Hauraki Depression prior to 6025 y B.P.
Muds range from silty clays to clayey silts and consist principally of volcanic glass, smectite and halloysite, with smaller amounts of other volcanic-derived siliciclasts and allophane and illite, as well as skeletal carbonate (mainly aragonite) and organic matter. A contemporaneous decrease in the abundance of volcanic glass (55-15 wt % down-core) and an increase in smectite concentration (8-45 wt % down-core) occurs with sub-bottom depth. Specific mineralogical analyses (XRD and IR) and evidence from scanning electron microscopy suggest the smectite is montmorillonitic in composition and authigenic in nature. Moreover, the absence of smectite in the bottom sediments of rivers draining the Hauraki Lowland precludes a detrital origin.
The diagenetic transformation of volcanic glass to smectite in sediments of the Firth of Thames is described by a sequential kinetic model which involves a parabolic dissolution coupled with a first order precipitation of smectite via the formation of an intermediate hydrated glass phase. The rate constant calculated from the sequential kinetic model is 3.35 x 10⁻⁴y⁻¹. The half-life of the glass is 1475 y, implying rapid early diagenetic alteration of volcanic glass to smectite to form late Holocene bentonitic deposits. Thermodynamic stability considerations imply that the first order precipitaion of smectite may be favoured by conditions of pH and Na⁺ activity typical of interstitial fluids having sea water salinity under mildly anoxic conditions
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
The Impact of Pharmacologic and Nonpharmacologic Interventions to Improve Physical Health Outcomes in People With Dementia:A Meta-Review of Meta-Analyses of Randomized Controlled Trials
No full textOBJECTIVES: We summarized and compared meta-analyses of pharmacologic and nonpharmacologic interventions targeting physical health outcomes among people with dementia.DESIGN: This is a systematic review and meta-analysis.SETTING AND PARTICIPANTS: People with dementia, confirmed through validated assessment measures.METHODS: Major databases were searched until October 21, 2019. Effect sizes [standardized mean difference (SMD)/Hedges g or risk ratio (RR)] were compared separately.RESULTS: Of 3773 search engine hits, 4 meta-analyses were included, representing 31 meta-analyzed trials and 10,054 study participants. Although meta-analyses were generally of adequate high quality, meta-analyzed studies were less so. Nutritional supplements were the only one to show a weight-increasing effect [SMD 0.53, 95% confidence interval (CI) 0.38-0.68, ie, medium effect; N = 12, n = 748]. Acetylcholinesterase inhibitors are associated with an increased risk for weight loss (RR 2.1, 95% CI 1.5‒3.0; N = 9, n = 7010). For the treatment of pain, sensory stimulation has a medium effect (SMD -0.58, 95% CI -0.99 to -0.17; N = 6, n = 199), whereas physical activity has a small effect (SMD -0.24, 95% CI -1.06 to 0.59; N = 2, n = 75). When exploring the characteristics of the psychosocial interventions, group-based interventions demonstrated a medium (SMD -0.55, 95% CI -1.02 to -0.09; N = 6, n = 157) and individual psychosocial interventions a small effect (SMD -0.27, 95% CI -1.06 to 0.53; N = 2, n = 55).CONCLUSIONS AND IMPLICATIONS: Despite frequent physical comorbidities, the current evidence for pharmacologic and nonpharmacologic interventions in people with dementia to prevent and treat these conditions is still in its infancy, and larger trials targeting a wide range of physical health outcomes are urgently needed. Based on the SMDs and RRs, nutritional supplements can be recommended as an intervention to treat malnutrition. Clinicians should be careful in treating patients with acetylcholinesterase inhibitors, as it shows medium weight reducing effects. For the treatment of comorbid pain, sensory stimulation and psychosocial interventions are recommended.</p
THE TRANSITION OF MOLECULAR OXYGEN
No full textAuthor Institution: Research School of Physical Sciences and Engineering, The Australian National University; Molecular Physics Laboratory, SRI InternationalThe origin of the intensity of the transition of molecular oxygen, first observed recently by Eppink et al. [J. Chem. Phys. 108, 1305 (1998).], is discussed. It is shown that the transition borrows its intensity principally from the dipole-allowed transition, through spin-orbit mixing between the and states. Estimated continuum photoabsorption cross sections and discrete oscillator strengths for the system are presented
Observations of Bºs→ψ(2S)η and Bº(s)→ψ(2S)π+π- decays
No full textFirst observations of the B0s
→ψ(2S)η, B0 →ψ(2S)π
+
π
− and B0s
→ψ(2S)π
+
π
− decays are made
using a dataset corresponding to an integrated luminosity of 1.0 fb−1 collected by the LHCb experiment in
proton–proton collisions at a centre-of-mass energy of
√
s = 7 TeV. The ratios of the branching fractions
of each of the ψ(2S) modes with respect to the corresponding J/ψ decays are
B(B0s
→ψ(2S)η)
÷
B(B0s
→J/ψη)
= 0.83± 0.14 (stat)±0.12 (syst) ±0.02 (B),
;
B(B0→ψ(2S)π
+
π
−
)
÷
B(B0→J/ψπ
+
π
−
)
= 0.56± 0.07 (stat)±0.05 (syst)± 0.01 (B),
;
B(B0s
→ψ(2S)π
+
π
−
)
÷
B(B0s
→J/ψπ
+
π
−
)
= 0.34± 0.04 (stat)±0.03 (syst)± 0.01 (B),
where the third uncertainty corresponds to the uncertainties of the dilepton branching fractions of the J/ψ
and ψ(2S) meson decays
The Grothendieck-Cousin complex on G/B x G/B
No full textIn his 1978 paper, The Grothendieck-Cousin complex of an induced representation, G. Kempf computes the Cousin complex corresponding to an induced representation of a reductive algebraic group G. His technique uses the geometry of the homogeneous space G/B, B being a Borel subgroup of G. The complex gives a resolution by B-modules, which easily yields the Weyl character formula.Instead of considering G/B, we analyze the analagous situation for . The Cousin complex corresponding to an induced representation in this case consists of G-modules. We are able to study the terms of the complex by exploiting parallels between the B-action on G/B and the G-action on --there is a natural one-to-one correspondence between the orbits of these actions. Our work here is greatly simplified by reducing to the affine situation and applying the theory of A-G modules. We construct a spectral sequence relating the terms of the complexes. Finally, an application to the theory of D-modules is given.Made available in DSpace on 2011-05-07T12:16:39Z (GMT). No. of bitstreams: 2
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G (A, B)-labeling of cacti over groups
No full text© 2016 Author(s). Let G be a group with nonempty subsets A and B. The graph G(A, B) is the simple graph obtained by deleting all loops from the graph whose vertex set is A and where vertices x and y are adjacent if and only if there is a b B such that xb = y or yb = x. In this paper, we present realizations of some cacti as G(A, B)\u27s
Measurement of the ratio of branching fractions B(B0→K∗0γ )/B(B0s→φγ ) and the directCP asymmetry inB 0→K∗0γ
No full textThe ratio of branching fractions of the radiative B decays B0→K⁎0γ and B0s→ϕγ has been measured using an integrated luminosity of 1.0 fb−1 of pp collision data collected by the LHCb experiment at a centre-of-mass energy of s√=7TeV. The value obtained is
B(B0→K⁎0γ)B(B0s→ϕγ)=1.23±0.06(stat.)±0.04(syst.)±0.10(fs/fd),
where the first uncertainty is statistical, the second is the experimental systematic uncertainty and the third is associated with the ratio of fragmentation fractions fs/fd. Using the world average value for B(B0→K⁎0γ), the branching fraction B(B0s→ϕγ) is measured to be (3.5±0.4)×10−5.
The direct CP asymmetry in B0→K⁎0γ decays has also been measured with the same data and found to be
ACP(B0→K⁎0γ)=(0.8±1.7(stat.)±0.9(syst.))%.
Both measurements are the most precise to date and are in agreement with the previous experimental results and theoretical expectations
The east coast of Scotland bottlenose dolphin population : improving understanding of ecology outside the Moray Firth SAC
No full textDirect numerical test of the B-G-K model equation by the DSMC method
No full textIn the present paper the rarefied gas how caused by the sudden change of the wall temperature and the Rayleigh problem are simulated by the DSMC method which has been validated by experiments both in global flour field and velocity distribution function level. The comparison of the simulated results with the accurate numerical solutions of the B-G-K model equation shows that near equilibrium the BG-K equation with corrected collision frequency can give accurate result but as farther away from equilibrium the B-G-K equation is not accurate. This is for the first time that the error caused by the B-G-K model equation has been revealed
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