287 research outputs found
The role of vitamins in oral health. A systematic review and meta-analysis
The association between vitamins and oral health have recently been discussed, yielding increased attention from medical and dental perspectives. The present review aimed to systematically evaluate and appraise the most recently scientific papers investigating the role of vitamins in the prevention and treatment of the main oral diseases as hard dental pathological processes and gum/periodontal disease. Randomized controlled trials, cross-sectional studies, cohort studies, comparative studies, validation studies and evaluation studies, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, reporting associations
between vitamins and oral diseases or the use of vitamins to prevent or treat oral diseases in patients of any age were included. PubMed, Embase and Scopus were searched to November 2019 using an ad hoc prepared search string. All the papers meeting the inclusion criteria were subjected to a quality assessment. The search identified 1597 papers; 741 were selected after removing duplicates. A total of 334 articles were excluded after title and abstract evaluation; 407 were assessed and 73 papers were full-text assessed; other 14 papers were discharged after full text evaluation, leaving finally 58 papers included. In general, there is weak evidence supporting the association between vitamins and both gingival/periodontal disease and hard dental pathological processes
Exploring and Exploiting Acceptor Preferences of the Human Polysialyltransferases as a Basis for an Inhibitor Screen
Yesα2,8-Linked polysialic acid (polySia) is an oncofoetal antigen with high abundance during embryonic development. It reappears in malignant tumours of neuroendocrine origin. Two polysialyltransferases (polySTs) ST8SiaII and IV are responsible for polySia biosynthesis. During development, both enzymes are essential to control polySia expression. However, in tumours ST8SiaII is the prevalent enzyme. Consequently, ST8SiaII is an attractive target for novel cancer therapeutics. A major challenge is the high structural and functional conservation of ST8SiaII and -IV. An assay system that enables differential testing of ST8SiaII and -IV would be of high value to search for specific inhibitors. Here we exploited the different modes of acceptor recognition and elongation for this purpose. With DMB-DP3 and DMB-DP12 (fluorescently labelled sialic acid oligomers with a degree of polymerisation of 3 and 12, respectively) we identified stark differences between the two enzymes. The new acceptors enabled the simple comparative testing of the polyST initial transfer rate for a series of CMP-activated and N-substituted sialic acid derivatives. Of these derivatives, the non-transferable CMP-Neu5Cyclo was found to be a new, competitive ST8SiaII inhibitor
Mechanics: non-classical, non-quantum
A non-classical, non-quantum theory, or NCQ, is any fully consistent theory
that differs fundamentally from both the corresponding classical and quantum
theories, while exhibiting certain features common to both. Such theories are
of interest for two primary reasons. Firstly, NCQs arise prominently in
semi-classical approximation schemes. Their formal study may yield improved
approximation techniques in the near-classical regime. More importantly for the
purposes of this note, it may be possible for NCQs to reproduce quantum results
over experimentally tested regimes while having a well defined classical limit,
and hence are viable alternative theories. We illustrate an NCQ by considering
an explicit class of NCQ mechanics. Here this class will be arrived at via a
natural generalization of classical mechanics formulated in terms of a
probability density functional
Measurement of event shape distributions and moments in e+e- -> hadrons at 91-209 GeV and a determination of alpha_s
We have studied hadronic events from e+e- annihilation data at centre-of-mass
energies from 91 to 209 GeV. We present distributions of event shape
observables and their moments at each energy and compare with QCD Monte Carlo
models. From the event shape distributions we extract the strong coupling
alpha_s and test its evolution with energy scale. The results are consistent
with the running of alpha_s expected from QCD. Combining all data, the value of
alpha_s(M_Z) is determined to be alpha_s(M_Z) = 0.1191 +- 0.0005 (stat.) +-
0.0010 (expt.) +- 0.0011 (hadr.) +- 0.0044 (theo.). The energy evolution of the
moments is also used to determine a value of alpha_s with slightly larger
errors: alpha_s(M_Z) = 0.1223 +- 0.0005 (stat.) +- 0.0014 (expt.) +- 0.0016
(hadr.) +0.0054 -0.0036 (theo.).Comment: 63 pages 26 fi
Searches for Gauge-Mediated Supersymmetry Breaking Topologies in e+e- collisions at LEP2
In gauge-mediated supersymmetry (SUSY) breaking (GMSB) models the lightest
supersymmetric particle (LSP) is the gravitino and the phenomenology is driven
by the nature of the next-to-lightest SUSY particle (NLSP) which is either the
lightest neutralino, the stau or mass degenerate sleptons. Since the NLSP decay
length is effectively unconstrained, searches for all possible lifetime and
NLSP topologies predicted by GMSB models in e+e- collisions are performed on
the data sample collected by OPAL at centre-of-mass energies up to 209 GeV at
LEP. Results independent of the NLSP lifetime are presented for all relevant
final states including direct NLSP pair-production and, for the first time,
also NLSP production via cascade decays of heavier SUSY particles. None of the
searches shows evidence for SUSY particle production. Cross-section limits are
presented at the 95% confidence level both for direct NLSP production and for
cascade decays, providing the most general, almost model independent results.
These results are then interpreted in the framework of the minimal GMSB (mGMSB)
model, where large areas of the accessible parameter space are excluded. In the
mGMSB model, the NLSP masses are constrained to be larger than 53.5 GeV/c^2,
87.4 GeV/c^2 and 91.9 GeV/c^2 in the neutralino, stau and slepton co-NLSP
scenarios, respectively. A complete scan on the parameters of the mGMSB model
is performed, constraining the universal SUSY mass scale Lambda from the direct
SUSY particle searches: Lambda > 40, 27, 21, 17, 15 TeV/c^2 for messenger
indices N=1, 2, 3, 4, 5 respectively, for all NLSP lifetimes.Comment: 4 pages, 2 figures. To appear in Proceedings of SUSY06, the 14th
International Conference on Supersymmetry and the Unification of Fundamental
Interactions, UC Irvine, California, 12-17 June 200
Flavour Independent hA Search and Two Higgs Doublet Model Interpretation of Neutral Higgs Boson Searches at LEP
Upper limits on the cross-section of the pair-production process e+e- -> h0A0
assuming 100% decays into hadrons, are derived from a new search for the h0A0
-> hadrons topology, independent of the hadronic flavour of the decay products.
Searches for the neutral Higgs bosons h0 and A0, are used to obtain constraints
on the Type II Two Higgs Doublet Model (2HDM(11)) with no CP violation in the
Higgs sector and no additional non Standard Model particles besides the five
Higgs bosons. The analysis combines LEP1 and LEP2 data collected with the OPAL
detctor up to the highest available centre-of-mass energies. The searches are
sensitive to the h0, A0 -> qq, gg,tau+tau- and h0 -> A0A0 decay modes of the
Higgs bosons. The 2HDM(II) parameter space is explored in a detailed scan.
Large regions of the 2HDM(II) parameter space are excluded at the 95% CL in the
(mh, mA), (mh, tanb) and (mA, tanb) planes, using both direct neutral Higgs
boson searches and indirect limits derived from Standard Model high precision
measurements. The region 1 lesssim mh lesssim 55 GeV and 3 lesssim mA lesssim
63 GeV is excluded at 95% CL independently of the choice of the 2HDM(II)
parameters.Comment: 37 pages, 11 figures, Submitted to Eur. Phys. J.
Measurement of the partial widths of the Z into up- and down-type quarks
Using the entire OPAL LEP1 on-peak Z hadronic decay sample, Z -> qbarq gamma
decays were selected by tagging hadronic final states with isolated photon
candidates in the electromagnetic calorimeter. Combining the measured rates of
Z -> qbarq gamma decays with the total rate of hadronic Z decays permits the
simultaneous determination of the widths of the Z into up- and down-type
quarks. The values obtained, with total errors, were Gamma u = 300 ^{+19}_{-18}
MeV and Gamma d = 381 ^{+12}_{-12} MeV. The results are in good agreement with
the Standard Model expectation.Comment: 22 pages, 5 figures, Submitted to Phys. Letts.
Measurement of the Strong Coupling alpha s from Four-Jet Observables in e+e- Annihilation
Data from e+e- annihilation into hadrons at centre-of-mass energies between
91 GeV and 209 GeV collected with the OPAL detector at LEP, are used to study
the four-jet rate as a function of the Durham algorithm resolution parameter
ycut. The four-jet rate is compared to next-to-leading order calculations that
include the resummation of large logarithms. The strong coupling measured from
the four-jet rate is alphas(Mz0)=
0.1182+-0.0003(stat.)+-0.0015(exp.)+-0.0011(had.)+-0.0012(scale)+-0.0013(mass)
in agreement with the world average. Next-to-leading order fits to the
D-parameter and thrust minor event-shape observables are also performed for the
first time. We find consistent results, but with significantly larger
theoretical uncertainties.Comment: 25 pages, 15 figures, Submitted to Euro. Phys. J.
Search for R-Parity Violating Decays of Scalar Fermions at LEP
A search for pair-produced scalar fermions under the assumption that R-parity
is not conserved has been performed using data collected with the OPAL detector
at LEP. The data samples analysed correspond to an integrated luminosity of
about 610 pb-1 collected at centre-of-mass energies of sqrt(s) 189-209 GeV. An
important consequence of R-parity violation is that the lightest supersymmetric
particle is expected to be unstable. Searches of R-parity violating decays of
charged sleptons, sneutrinos and squarks have been performed under the
assumptions that the lightest supersymmetric particle decays promptly and that
only one of the R-parity violating couplings is dominant for each of the decay
modes considered. Such processes would yield final states consisting of
leptons, jets, or both with or without missing energy. No significant
single-like excess of events has been observed with respect to the Standard
Model expectations. Limits on the production cross- section of scalar fermions
in R-parity violating scenarios are obtained. Constraints on the supersymmetric
particle masses are also presented in an R-parity violating framework analogous
to the Constrained Minimal Supersymmetric Standard Model.Comment: 51 pages, 24 figures, Submitted to Eur. Phys. J.
Measurement of Rb in e+e- Collisions at 182 - 209 GeV
Measurements of Rb, the ratio of the bbbar cross-section to the qqbar cross-
section in e+e- collisions, are presented. The data were collected by the OPAL
experiment at LEP at centre-of-mass energies between 182 GeV and 209 GeV.
Lepton, lifetime and event shape information is used to tag events containing b
quarks with high efficiency. The data are compatible with the Standard Model
expectation. The mean ratio of the eight measurements reported here to the
Standard Model prediction is 1.055+-0.031+-0.037, where the first error is
statistical and the second systematic.Comment: 21 pages, 5 figures, Submitted to Phys. Letts
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