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The biological embedding of early-life socioeconomic status and family adversity in children's genome-wide DNA methylation.
AimTo examine variation in child DNA methylation to assess its potential as a pathway for effects of childhood social adversity on health across the life course.Materials & methodsIn a diverse, prospective community sample of 178 kindergarten children, associations between three types of social experience and DNA methylation within buccal epithelial cells later in childhood were examined.ResultsFamily income, parental education and family psychosocial adversity each associated with increased or decreased DNA methylation (488, 354 and 102 sites, respectively) within a unique set of genomic CpG sites. Gene ontology analyses pointed to genes serving immune and developmental regulation functions.ConclusionFindings provided support for DNA methylation as a biomarker linking early-life social experiences with later life health in humans
Assemblage structure: an overlooked component of human-mediated species movements among freshwater ecosystems
The spread and impact of alien species among freshwater ecosystems has increased with global trade and human movement; therefore, quantifying the role of anthropogenic and ecological factors that increase the risk of invasion is an important conservation goal. Two factors considered as null models when assessing the potential for invasion are colonization pressure (i.e., the number of species introduced) and propagule pressure [i.e., the number (propagule size), and frequency (propagule number), of individuals of each species introduced]. We translate the terminology of species abundance distributions to the invasion terminology of propagule size and colonization size (PS and CS, respectively). We conduct hypothesis testing to determine the underlying statistical species abundance distribution for zooplankton assemblages transported between freshwater ecosystems; and, on the basis of a lognormal distribution, construct four hypothetical assemblages spanning assemblage structure, rank-abundance gradient (e.g., even vs uneven), total abundance (of all species combined), and relative contribution of PS vs CS. For a given CS, many combinations of PS and total abundance can occur when transported assemblages conform to a lognormal species abundance distribution; therefore, for a given transportation event, many combinations of CS and PS are possible with potentially different ecological outcomes. An assemblage exhibiting high PS but low CS (species poor, but highly abundant) may overcome demographic barriers to establishment, but with lower certainty of amenable environmental conditions in the recipient region; whereas, the opposite extreme, high CS and low PS (species rich, but low abundance per species) may provide multiple opportunities for one of n arriving species to circumvent environmental barriers, albeit with lower potential to overcome demographic constraints. Species abundance distributions and the corresponding influence of CS and PS are some of many influential factors (e.g., demographic and genetic stochasticity, environmental variability, composition of recipient ecosystems) that will help refine an understanding of establishment risk following the human-mediated movement of species
Aging in a Two-Dimensional Ising Model with Dipolar Interactions
Aging in a two-dimensional Ising spin model with both ferromagnetic exchange
and antiferromagnetic dipolar interactions is established and investigated via
Monte Carlo simulations. The behaviour of the autocorrelation function
is analyzed for different values of the temperature, the waiting
time and the quotient , and being the
strength of exchange and dipolar interactions respectively. Different
behaviours are encountered for at low temperatures as is
varied. Our results show that, depending on the value of , the dynamics
of this non-disordered model is consistent either with a slow domain dynamics
characteristic of ferromagnets or with an activated scenario, like that
proposed for spin glasses.Comment: 4 pages, RevTex, 5 postscript figures; acknowledgment added and some
grammatical corrections in caption
Reorientation transition of ultrathin ferromagnetic films
We demonstrate that the reorientation transition from out-of-plane to
in-plane magnetization with decreasing temperature as observed experimentally
in Ni-films on Cu(001) can be explained on a microscopic basis. Using a
combination of mean field theory and perturbation theory, we derive an analytic
expression for the temperature dependent anisotropy. The reduced magnetization
in the film surface at finite temperatures plays a crucial role for this
transition as with increasing temperature the influence of the uniaxial
anisotropies is reduced at the surface and is enhanced inside the film.Comment: 4 pages(RevTeX), 3 figures (EPS
Magnetic Properties of 2-Dimensional Dipolar Squares: Boundary Geometry Dependence
By means of the molecular dynamics simulation on gradual cooling processes,
we investigate magnetic properties of classical spin systems only with the
magnetic dipole-dipole interaction, which we call dipolar systems. Focusing on
their finite-size effect, particularly their boundary geometry dependence, we
study two finite dipolar squares cut out from a square lattice with
and , where is an angle between the direction of the lattice axis
and that of the square boundary. Distinctly different results are obtained in
the two dipolar squares. In the square, the ``from-edge-to-interior
freezing'' of spins is observed. Its ground state has a multi-domain structure
whose domains consist of the two among infinitely (continuously) degenerated
Luttinger-Tisza (LT) ground-state orders on a bulk square lattice, i.e., the
two antiferromagnetically aligned ferromagnetic chains (af-FMC) orders directed
in parallel to the two lattice axes. In the square, on the other
hand, the freezing starts from the interior of the square, and its ground state
is nearly in a single domain with one of the two af-FMC orders. These geometry
effects are argued to originate from the anisotropic nature of the
dipole-dipole interaction which depends on the relative direction of sites in a
real space of the interacting spins.Comment: 21 pages, 13 figures, submitted to Journal of Physical Society Japa
Association between intrarenal arterial resistance and diastolic dysfunction in type 2 diabetes
<p>Abstract</p> <p>Background</p> <p>In comparison to the well established changes in compliance that occur at the large vessel level in diabetes, much less is known about the changes in compliance of the cardiovascular system at the end-organ level. The aim of this study was therefore to examine whether there was a correlation between resistance of the intrarenal arteries of the kidney and compliance of the left ventricle, as estimated by measurements of diastolic function, in subjects with type 2 diabetes.</p> <p>Methods</p> <p>We studied 167 unselected clinic patients with type 2 diabetes with a kidney duplex scan to estimate intrarenal vascular resistance, i.e. the resistance index (RI = peak systolic velocity-minimum diastolic velocity/peak systolic velocity) and a transthoracic echocardiogram (TTE) employing tissue doppler studies to document diastolic and systolic ventricular function.</p> <p>Results</p> <p>Renal RI was significantly higher in subjects with diastolic dysfunction (0.72 ± 0.05) when compared with those who had a normal TTE examination (0.66 ± 0.06, p < 0.01). Renal RI values were correlated with markers of diastolic dysfunction including the E/Vp ratio (r = 0.41, p < 0.001), left atrial area (r = 0.36, p < 0.001), the E/A ratio (r = 0.36, p < 0.001) and the E/E' ratio (r = 0.31, p < 0.001). These associations were independent of systolic function, hypertension, the presence and severity of chronic kidney disease, the use of renin-angiotensin inhibitors and other potentially confounding variables.</p> <p>Conclusion</p> <p>Increasing vascular resistance of the intrarenal arteries was associated with markers of diastolic dysfunction in subjects with type 2 diabetes. These findings are consistent with the hypothesis that vascular and cardiac stiffening in diabetes are manifestations of common pathophysiological mechanisms.</p
Dipolar interaction between two-dimensional magnetic particles
We determine the effective dipolar interaction between single domain
two-dimensional ferromagnetic particles (islands or dots), taking into account
their finite size. The first correction term decays as 1/D^5, where D is the
distance between particles. If the particles are arranged in a regular
two-dimensional array and are magnetized in plane, we show that the correction
term reinforces the antiferromagnetic character of the ground state in a square
lattice, and the ferromagnetic one in a triangular lattice. We also determine
the dipolar spin-wave spectrum and evaluate how the Curie temperature of an
ensemble of magnetic particles scales with the parameters defining the particle
array: height and size of each particle, and interparticle distance. Our
results show that dipolar coupling between particles might induce ferromagnetic
long range order at experimentally relevant temperatures. However, depending on
the size of the particles, such a collective phenomenon may be disguised by
superparamagnetism.Comment: 11 pages, 5 figure
Ferromagnetism and Temperature-Driven Reorientation Transition in Thin Itinerant-Electron Films
The temperature-driven reorientation transition which, up to now, has been
studied by use of Heisenberg-type models only, is investigated within an
itinerant-electron model. We consider the Hubbard model for a thin fcc(100)
film together with the dipole interaction and a layer-dependent anisotropy
field. The isotropic part of the model is treated by use of a generalization of
the spectral-density approach to the film geometry. The magnetic properties of
the film are investigated as a function of temperature and film thickness and
are analyzed in detail with help of the spin- and layer-dependent quasiparticle
density of states. By calculating the temperature dependence of the
second-order anisotropy constants we find that both types of reorientation
transitions, from out-of-plane to in-plane (``Fe-type'') and from in-plane to
out-of-plane (``Ni-type'') magnetization are possible within our model. In the
latter case the inclusion of a positive volume anisotropy is vital. The
reorientation transition is mediated by a strong reduction of the surface
magnetization with respect to the inner layers as a function of temperature and
is found to depend significantly on the total band occupation.Comment: 10 pages, 8 figures included (eps), Phys Rev B in pres
In situ hatching of invertebrate diapausing eggs from ships’ ballast sediment
Ships that enter the Great Lakes laden with cargo carry only residual ballast water and sediment in ballast tanks. These ships are designated ‘no ballast on board’ (NOBOB) and constitute > 90% of inbound traffic. We conducted in situ experiments using emergence traps to assess the viability and the introduction potential of invertebrate diapausing stages present in ships’ ballast sediment. All trials commenced while vessels operated on the lower lakes (Erie, Ontario) and were completed 6–11 days later at ports on the upper lakes (Michigan, Lake Superior). Eight trials were conducted on four ships using five different ballast sediments. Hatching was observed on every ship, although not from all sediments on all ships. Overall hatch rates were very low (0.5 individuals per 500 g sediment), typically involving activation of < 0.05% of total eggs present. Five species of rotifers and copepod nauplii were hatched from ballast sediments, although only one or two species typically hatched from any one sediment. Results of this study indicate that hatching of diapausing eggs contained in ballast sediment of NOBOB ships poses a relatively low risk of invasion to the Great Lakes. However, as reproduction may occur in tanks, and non-indigenous species may be involved in numerous introduction events, the risk posed by this vector is small but potentially important. While dormancy is a characteristic enabling enhanced survival during transportation in ballast tanks, it becomes a hindrance for introduction.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72804/1/j.1366-9516.2005.00150.x.pd
Metric Features of a Dipolar Model
The lattice spin model, with nearest neighbor ferromagnetic exchange and long
range dipolar interaction, is studied by the method of time series for
observables based on cluster configurations and associated partitions, such as
Shannon entropy, Hamming and Rohlin distances. Previous results based on the
two peaks shape of the specific heat, suggested the existence of two possible
transitions. By the analysis of the Shannon entropy we are able to prove that
the first one is a true phase transition corresponding to a particular melting
process of oriented domains, where colored noise is present almost
independently of true fractality. The second one is not a real transition and
it may be ascribed to a smooth balancing between two geometrical effects: a
progressive fragmentation of the big clusters (possibly creating fractals), and
the slow onset of a small clusters chaotic phase. Comparison with the nearest
neighbor Ising ferromagnetic system points out a substantial difference in the
cluster geometrical properties of the two models and in their critical
behavior.Comment: 20 pages, 15 figures, submitted to JPhys
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