452 research outputs found
Physical activity and healthy ageing: A systematic review and meta-analysis of longitudinal cohort studies.
BACKGROUND: Older people constitute a significant proportion of the total population and their number is projected to increase by more than half by 2030. This increasing probability of late survival comes with considerable individual, economic and social impact. Physical activity (PA) can influence the ageing process but the specific relationship with healthy ageing (HA) is unclear. METHODS: We conducted a systematic review and meta-analysis of longitudinal studies examining the associations of PA with HA. Studies were identified from a systematic search across major electronic databases from inception as January 2017. Random-effect meta-analysis was performed to calculate a pooled effect size (ES) and 95% CIs. Studies were assessed for methodological quality. RESULTS: Overall, 23 studies were identified including 174,114 participants (30% men) with age ranges from 20 to 87 years old. There was considerable heterogeneity in the definition and measurement of HA and PA. Most of the identified studies reported a significant positive association of PA with HA, six reported a non-significant. Meta-analysis revealed that PA is positively associated with HA (ES: 1.39, 95% CI=1.23-1.57, n=17) even if adjusted for publication bias (ES: 1.27, 95% CI=1.11-1.45, n=20). CONCLUSIONS: There is consistent evidence from longitudinal observational studies that PA is positively associated with HA, regardless of definition and measurement. Future research should focus on the implementation of a single metric of HA, on the use of objective measures for PA assessment and on a full-range of confounding adjustment. In addition, our research indicated the limited research on ageing in low-and-middle income countries
Palladium(II) complexes of quinolinylaminophosphonates: synthesis, structural characterization, antitumor and antimicrobial activity
Three types of palladium(II) halide complexes of quinolinylaminophosphonates have been synthesized and studied. Diethyl and dibutyl [alpha-anilino-(quinolin-2-ylmethyl)]phosphonates (L1, 12) act as N,N-chelate ligands through the quinoline and aniline nitrogens giving complexes cis-[Pd(L1/12)X-2] (X Cl, Br) (1-4). Their 3-substituted analogues [alpha-anilino-(quinolin-3-ylmethyl)]phosphonates (L3, L4) form dihalidopalladium complexes trans-[Pd(L3/L4)(2)X-2] (5-8), with trans N-bonded ligand molecules only through the quinoline nitrogen. Dialkyl [alpha-(quinolin-3-ylamino)-N-benzyl]phosphonates (L5, L6) give tetrahalidodipalladium complexes [Pd-2(L5/L6)(3)X-4] (9-12), containing one bridging and two terminal ligand molecules. The bridging molecule is bonded to the both palladium atoms, one through the quinoline and the other through the aminoquinoline nitrogen, whereas terminal ligand molecules are coordinated each only to one palladium via the quinoline nitrogen. Each palladium ion is also bonded to two halide ions in a trans square-planar fashion. The new complexes were identified and characterized by elemental analyses and by IR, UV-visible, H-1, C-13 and P-31 nuclear magnetic resonance and ESI-mass spectroscopic studies. The crystal structures of complexes 1-4 and 6 were determined by X-ray structure analysis. The antitumor activity of complexes in vitro was investigated on several human tumor cell lines and the highest activity with cell growth inhibitory effects in the low micromolar range was observed for dipalladium complexes 11 and 12 derived from dibutyl ester L6. The antimicrobial properties in vitro of ligands and their complexes were studied using a wide spectrum of bacterial and fungal strains. No specific activity was noted. Only ligands L3 and L4 and tetrahalidodipalladium complexes 9 and 11 show poor activities against some Gram positive bacteria
The Mass and Ion Kinetic Energy Spectra of Fluoro-Chloro Substituted Norbornanes and Nortricyclanes
The mass and ion kinetic energy spectra of difluoro- and fluoro-
chloro-norbornanes and fluoro-chloro-nortricyclanes have been
examined. In several instances the similarity of the mass spectra
makes it impossible to distinguish the diastereoisomers from each
other. In contrast, however, their ion kinetic energy spectra differ
clearly and allow unambiguous differentiation of the stereoisomers
Annihilation of edge dislocations in smectic A liquid crystals
This paper presents a theoretical study of the annihilation of edge dislocations in the same smectic plane in a bulk smectic-A phase. We use a time-dependent Landau-Ginzburg approach where the smectic ordering is described by the complex order parameter psi( r--> ,t) =eta e(iphi) . This quantity allows both the degree of layering and the position of the layers to be monitored. We are able to follow both precollision and postcollision regimes, and distinguish different early and late behaviors within these regimes. The early precollision regime is driven by changes in the phi ( r--> ) configuration. The relative velocity of the defects is approximately inversely proportional to the interdefect separation distance. In the late precollision regime the symmetry changes within the cores of defects also become influential. Following the defect collision, in the early postcollision stage, bulk layer order is approached exponentially in time. At very late times, however, there seems to be a long-time power-law tail in the order parameter fluctuation relaxation
Inhibition of ache by malathion and some structuraly similar compounds
Inhibition of bovine serum acetylcholinesterase by in vitro exposure to malathion, malaoxon, isomalathion and diethyl maleate was investigated to elucidate the mechanism of the enzyme interaction with structurally similar organophosphorus compounds. IC50 (half maximum inhibitory concentrations) were determined by Hill analysis of experimentally obtained inhibition curves. The values (2.87 ± 0.24)x10-6 M, (2.65±0.61)x10-6M, (3.01±0.36)x10-4 M and (5.69 ±0.7)x10-2 M were obtained for malaoxon, isomalathion, malathion and their hydrolysis product diethyl maleate, respectively. The relationship between the structure of the compounds and their potency to inhibit the enzyme activity was discussed.Physical chemistry 2006 : 8th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-29 September 200
Development and mining of a database of historic European paper properties
A database of historic paper properties was developed using 729 samples of European origin (1350–1990), analysed for acidity, degree or polymerisation (DP), molecular weight of cellulose, grammage, tensile strength, as well as contents of ash, aluminium, carbonyl groups, rosin, protein, lignin and fibre furnish. Using Spearman’s rank correlation coefficient and principal component analysis, the data were examined with respect to methods of manufacture, as well as chemical stability of paper. Novel patterns emerged related to loss of DP and accumulation of carbonyl groups and acidity with time and the role of lignin and rosin, as well as rate of degradation (k = 10−5 year−1) at room conditions. In-depth understanding of long-term degradation of lignin and rosin is needed to better understand the relationships between composition and degradation of historic paper. This study highlights the importance of mining significant volumes of analytical data, and its variability, obtained from real historic objects
Interaction and flocculation of spherical colloids wetted by a surface-induced corona of paranematic order
Particles dispersed in a liquid crystal above the nematic-isotropic phase
transition are wetted by a surface-induced corona of paranematic order. Such
coronas give rise to pronounced two-particle interactions. In this article, we
report details on the analytical and numerical study of these interactions
published recently [Phys. Rev. Lett. 86, 3915 (2001)]. We especially
demonstrate how for large particle separations the asymptotic form of a Yukawa
potential arises. We show that the Yukawa potential is a surprisingly good
description for the two-particle interactions down to distances of the order of
the nematic coherence length. Based on this fact, we extend earlier studies on
a temperature induced flocculation transition in electrostatically stabilized
colloidal dispersions [Phys. Rev. E 61, 2831 (2000)]. We employ the Yukawa
potential to establish a flocculation diagram for a much larger range of the
electrostatic parameters, namely the surface charge density and the Debye
screening length. As a new feature, a kinetically stabilized dispersion close
to the nematic-isotropic phase transition is found.Comment: Revtex v4.0, 16 pages, 12 Postscript figures. Accepted for
publication in Phys. Rev.
Nematic-Wetted Colloids in the Isotropic Phase: Pairwise Interaction, Biaxiality and Defects
We calculate the interaction between two spherical colloidal particles
embedded in the isotropic phase of a nematogenic liquid. The surface of the
particles induces wetting nematic coronas that mediate an elastic interaction.
In the weak wetting regime, we obtain exact results for the interaction energy
and the texture, showing that defects and biaxiality arise, although they are
not topologically required. We evidence rich behaviors, including the
possibility of reversible colloidal aggregation and dispersion. Complex
anisotropic self-assembled phases might be formed in dense suspensions.Comment: 4 pages, 6 figure
Language comparison via network topology
Modeling relations between languages can offer understanding of language
characteristics and uncover similarities and differences between languages.
Automated methods applied to large textual corpora can be seen as opportunities
for novel statistical studies of language development over time, as well as for
improving cross-lingual natural language processing techniques. In this work,
we first propose how to represent textual data as a directed, weighted network
by the text2net algorithm. We next explore how various fast,
network-topological metrics, such as network community structure, can be used
for cross-lingual comparisons. In our experiments, we employ eight different
network topology metrics, and empirically showcase on a parallel corpus, how
the methods can be used for modeling the relations between nine selected
languages. We demonstrate that the proposed method scales to large corpora
consisting of hundreds of thousands of aligned sentences on an of-the-shelf
laptop. We observe that on the one hand properties such as communities, capture
some of the known differences between the languages, while others can be seen
as novel opportunities for linguistic studies
Learning Interpretable Rules for Multi-label Classification
Multi-label classification (MLC) is a supervised learning problem in which,
contrary to standard multiclass classification, an instance can be associated
with several class labels simultaneously. In this chapter, we advocate a
rule-based approach to multi-label classification. Rule learning algorithms are
often employed when one is not only interested in accurate predictions, but
also requires an interpretable theory that can be understood, analyzed, and
qualitatively evaluated by domain experts. Ideally, by revealing patterns and
regularities contained in the data, a rule-based theory yields new insights in
the application domain. Recently, several authors have started to investigate
how rule-based models can be used for modeling multi-label data. Discussing
this task in detail, we highlight some of the problems that make rule learning
considerably more challenging for MLC than for conventional classification.
While mainly focusing on our own previous work, we also provide a short
overview of related work in this area.Comment: Preprint version. To appear in: Explainable and Interpretable Models
in Computer Vision and Machine Learning. The Springer Series on Challenges in
Machine Learning. Springer (2018). See
http://www.ke.tu-darmstadt.de/bibtex/publications/show/3077 for further
informatio
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