3,152 research outputs found
Mental Illness and Mental Health: The Two Continua Model Across the Lifespan
Mental health has long been defined as the absence of psychopathologies, such as depression and anxiety. The absence of mental illness, however, is a minimal outcome from a psychological perspective on lifespan development. This article therefore focuses on mental illness as well as on three core components of positive mental health: feelings of happiness and satisfaction with life (emotional well-being), positive individual functioning in terms of self-realization (psychological well-being), and positive societal functioning in terms of being of social value (social well-being). The two continua model holds that mental illness and mental health are related but distinct dimensions. This model was studied on the basis of a cross-sectional representative internet survey of Dutch adults (NÂ =Â 1,340; 18â87Â years). Mental illness was measured with the Brief Symptom Inventory and mental health with the Mental Health Continuum Short Form. It was found that older adults, except for the oldest-old, scored lower on psychopathological symptoms and were less likely to be mentally ill than younger adults. Although there were fewer age differences for mental health, older adults experienced more emotional, similar social and slightly lower psychological well-being. In sum, todayâs older adults have fewer mental illness problems, but they are not in a better positive mental health than todayâs younger adults. These findings support the validity of the two continua model in adult development
The Potential Energy Landscape and Mechanisms of Diffusion in Liquids
The mechanism of diffusion in supercooled liquids is investigated from the
potential energy landscape point of view, with emphasis on the crossover from
high- to low-T dynamics. Molecular dynamics simulations with a time dependent
mapping to the associated local mininum or inherent structure (IS) are
performed on unit-density Lennard-Jones (LJ). New dynamical quantities
introduced include r2_{is}(t), the mean-square displacement (MSD) within a
basin of attraction of an IS, R2(t), the MSD of the IS itself, and g_{loc}(t)
the mean waiting time in a cooperative region. At intermediate T, r2_{is}(t)
posesses an interval of linear t-dependence allowing calculation of an
intrabasin diffusion constant D_{is}. Near T_{c} diffusion is intrabasin
dominated with D = D_{is}. Below T_{c} the local waiting time tau_{loc} exceeds
the time, tau_{pl}, needed for the system to explore the basin, indicating the
action of barriers. The distinction between motion among the IS below T_{c} and
saddle, or border dynamics above T_{c} is discussed.Comment: submitted to pr
Inherent-Structure Dynamics and Diffusion in Liquids
The self-diffusion constant D is expressed in terms of transitions among the
local minima of the potential (inherent structure, IS) and their correlations.
The formulae are evaluated and tested against simulation in the supercooled,
unit-density Lennard-Jones liquid. The approximation of uncorrelated
IS-transition (IST) vectors, D_{0}, greatly exceeds D in the upper temperature
range, but merges with simulation at reduced T ~ 0.50. Since uncorrelated IST
are associated with a hopping mechanism, the condition D ~ D_{0} provides a new
way to identify the crossover to hopping. The results suggest that theories of
diffusion in deeply supercooled liquids may be based on weakly correlated IST.Comment: submitted to PR
Instantaneous Normal Mode analysis of liquid HF
We present an Instantaneous Normal Modes analysis of liquid HF aimed to
clarify the origin of peculiar dynamical properties which are supposed to stem
from the arrangement of molecules in linear hydrogen-bonded network. The
present study shows that this approach is an unique tool for the understanding
of the spectral features revealed in the analysis of both single molecule and
collective quantities. For the system under investigation we demonstrate the
relevance of hydrogen-bonding ``stretching'' and fast librational motion in the
interpretation of these features.Comment: REVTeX, 7 pages, 5 eps figures included. Minor changes in the text
and in a figure. Accepted for publication in Phys. Rev. Let
Configurational entropy of hard spheres
We numerically calculate the configurational entropy S_conf of a binary
mixture of hard spheres, by using a perturbed Hamiltonian method trapping the
system inside a given state, which requires less assumptions than the previous
methods [R.J. Speedy, Mol. Phys. 95, 169 (1998)]. We find that S_conf is a
decreasing function of packing fraction f and extrapolates to zero at the
Kauzmann packing fraction f_K = 0.62, suggesting the possibility of an ideal
glass-transition for hard spheres system. Finally, the Adam-Gibbs relation is
found to hold.Comment: 10 pages, 6 figure
Stigma as a fundamental hindrance to the United States opioid overdose crisis response.
Alexander Tsai and co-authors discuss the role of stigma in responses to the US opioid crisis
Instantaneous Normal Mode Analysis of Supercooled Water
We use the instantaneous normal mode approach to provide a description of the
local curvature of the potential energy surface of a model for water. We focus
on the region of the phase diagram in which the dynamics may be described by
the mode-coupling theory. We find, surprisingly, that the diffusion constant
depends mainly on the fraction of directions in configuration space connecting
different local minima, supporting the conjecture that the dynamics are
controlled by the geometric properties of configuration space. Furthermore, we
find an unexpected relation between the number of basins accessed in
equilibrium and the connectivity between them.Comment: 5 pages, 4 figure
Synthesis and characterisation of ruthenium complexes containing a pendent catechol ring
A series of [Ru(bipy)âL]âș and [Ru(phen)âL]âș complexes where L is 2-[5-(3,4-dimethoxyphenyl)-4H-1,2,4-triazol-3-yl]pyridine (HL1) and 4-(5-pyridin-2-yl-4H-1,2,4-triazol-3-yl)benzene-1,2-diol (HL2) are reported. The compounds obtained have been characterised using X-ray crystallography, NMR, UV/Vis and emission spectroscopies. Partial deuteriation is used to determine the nature of the emitting state and to simplify the NMR spectra. The acid-base properties of the compounds are also investigated. The electronic structures of [Ru(bipy)âL1]âș and Ru(bipy)âHL1]ÂČâș are examined using ZINDO. Electro and spectroelectrochemical studies on [Ru(bipy)â(L2)]âș suggest that proton transfer between the catechol and triazole moieties on L2 takes place upon oxidation of the L2 ligand
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