49 research outputs found

### Basic Psychological Needs, Suicidal Ideation, and Risk for Suicidal Behavior in Young Adults

Associations between the satisfaction of basic psychological needs of autonomy, competence, and relatedness with current suicidal ideation and risk for suicidal behavior were examined. Two logistic regressions were conducted with a cross-sectional database of 440 university students to examine the association of need satisfaction with suicidal ideation and risk for suicidal behavior, while controlling for demographics and depressive symptoms. Suicidal ideation was reported by 15% of participants and 18% were found to be at risk for suicidal behavior. A one standard deviation increase in need satisfaction reduced the odds of suicidal ideation by 53%, OR (95% CI) = 0.47 (0.33–0.67), and the odds of being at risk for suicidal behavior by 50%, OR (95% CI) = 0.50 (0.37–0.69). Young adults whose basic psychological needs are met may be less likely to consider suicide and engage in suicidal behavior. Prospective research is needed to confirm these associations

### A Systematic Review of Social Factors and Suicidal Behavior in Older Adulthood

Suicide in later life is a global public health problem. The aim of this review was to conduct a systematic analysis of studies with comparison groups that examined the associations between social factors and suicidal behavior (including ideation, non-fatal suicidal behavior, or deaths) among individuals aged 65 and older. Our search identified only 16 articles (across 14 independent samples) that met inclusion criteria. The limited number of studies points to the need for further research. Included studies were conducted in Canada (n = 2), Germany (n = 1), Hong Kong (n = 1), Japan (n = 1), Singapore (n = 1), Sweden (n = 2), Taiwan (n = 1), the U.K. (n = 2), and the U.S. (n = 3). The majority of the social factors examined in this review can be conceptualized as indices of positive social connectedness—the degree of positive involvement with family, friends, and social groups. Findings indicated that at least in industrialized countries, limited social connectedness is associated with suicidal ideation, non-fatal suicidal behavior, and suicide in later life. Primary prevention programs designed to enhance social connections as well as a sense of community could potentially decrease suicide risk, especially among men

### Phase transitions and coarse graining for a system of particles in the continuum

This work is devoted to prove rigorously the existence of a liquid-vapor branch in the
phase diagram of
uids, when considering a system of particles in Rd interacting with a
reasonable potential with both long and short range contributions.
The model we consider is a variant of the model introduced by Lebowitz, Mazel and
Presutti ([1]), obtained by adding a hard core interaction to the original Kac potential inter-
action, the rst acting on a di erent scale.
Model:
Let q = (q1; :::qn) denote a con guration of n particles in Rd with dimension d 2. The
hamiltonian for the LMP model is given by the following function:
HLMP
;
(q) =
Z
Rd
e (
(r; q)) dr
where
e ( ) =
2
2
+
4
4!
is the energy density with a quadratic repulsive term and a quartic attractive term and
(r; q) :=
X
qi2q
J
(r; qi)
is the local particle density at r 2 Rd. The local density is de ned through Kac potentials,
i.e. functions which scale in the following way: J
(r; r0) =
dJ(
r;
r0), where J(r; r0) is
a symmetric, translation invariant (i.e. J(r; r0) = J(0; r0 r)) smooth probability kernel
supposed for simplicity to vanish for jr r0j 1. Thus the range of the interaction has
order
1 (for both repulsive and attractive potentials) and the \Kac scaling parameter"
is
assumed to be small. This choice of the potentials makes the LMP model a perturbation of the mean eld, in the sense that when taking the thermodynamic limit followed by the limit
! 0 the free energy is equivalent to the free energy in the van der Waals description.
Note that the LMP interaction can be written in terms of one, two and four body poten-
tials in the following way:
HLMP
;
(q) = jqj
1
2!
X
i6=j
J(2)
(qi; qj) +
1
4!
X
i16=:::6=i4
J(4)
(qi1 ; :::; qi4); (1.0.1)
where
J(2)
(qi; qj) =
Z
J
(r; qi)J
(r; qj) dr (1.0.2)
J(4)
(qi1 ; :::; qi4) =
Z
J
(r; qi1) J
(r; qi4) dr:
In the model with hard cores the phase space is restricted by adding an interaction which
is = 1 when the particles get too much close with each other and is 0 when the particles are
far. Hence the interaction is given by
Hhc(q) :=
X
i<j
V hc(qi; qj)
where V hc : Rd ! R is pair potential de ned as:
V hc(qi; qj) =
8><
>:
+1 if jqi qj j R
0 if jqi qj j > R
with R the radius of the hard spheres and = jB0(R)j their volume.
Result:
The main goal of this manuscript is to prove perturbativly that by adding a hard core
interaction to the LMP model, with the hard core radius R su ciently small, the LMP liquid-
vapor phase transition is essentially una ected. Hence, we prove existence of two di erent
Gibbs measures corresponding to the two phases.
Let us de ne the grand canonical measure in the region Rd and boundary conditions
q 2 Q c
as:
; ;R; (dqj q) = Z 1
; ;R; ( j q)e H
;R; (qj q) (dq):
Then the main theorem is the following Theorem 1.0.1. Consider the model with hamiltonian HLMP
;
(q) + Hhc(q) in dimension
d 2. There are R0, c;R; 0;R and for any 0 < R R0 and 2 ( c;R; 0;R) there is
;R > 0 so that for any
;R there is ;
;R such that:
There are two distinct DLR measures
;
;R with chemical potential ;
;R and inverse tem-
perature and two di erent densities: 0 < ;
;R; < ;
;R;+.
Thus we prove the existence of two distinct states, which are interpreted as the two pure
phases of the system: +
;
;R describes the liquid phase with density ;
;R;+ while
;
;R
describes the vapor phase, with the smaller density ;
;R; .
;
;R; and ;
;R have limit as
! 0, the limit being ;R; < ;R;+ and ( ;R) which
are respectively densities and chemical potential for which there is a phase transition in the
mean eld model.
The critical temperature c;R is close to the analogous critical value for the LMP model
for the volume of the hard cores small enough:
c;R = LMP
c ( LMP
c )2=3 + O( 2); LMP
c = 3=23=2:
Our proof will follow Pirokov-Sinai theory in the version proposed by Zahradn k, [3],
which involves the notion of cuto weights. The analysis is based on the ideas of coarse
graining and contour model and the goal is to prove an analogous of the Peierls argument for
discrete systems.
Crucial ingredient in the proof of Theorem 1.0.1 is to show the convergence of the cluster
expansion for the hard spheres gas in the canonical ensemble when the density is small,
small enough. This is the content of a recent paper [2]