18,276 research outputs found
'POWs and purge victims: attitudes towards party rehabilitation, 1956-57'
In the wake of Stalin's death in 1953 and Khrushchev's Secret Speech three years later, many Soviet citizens hoped that past injustices would now be put right. For some, this meant the right to rejoin the Communist Party. This article explores how former party members - including many returning from the camps - sought rehabilitation in the years 1956 to 1957. Focusing in particular on the party organization in Vladimir province, the article examines the differing ways POWs and purge victims were treated, and asks how far the decisions made by the party elite in this oblast' reflected central policy or local concerns
The prenatal effects of the Christchurch earthquake on executive function at five years of age : a thesis presented in partial fulfilment of the requirements for the degree of Masters of Educational Psychology at Massey University
Despite the frequency of earthquakes, particularly in New Zealand, little is known about
the long-term effects that they can have on vulnerable populations, such as mothers and
unborn babies. This study looks at the way in which a major earthquake can impact on
neurodevelopment, specifically the executive function (EF) abilities of children five
years following the disaster. The aims of this study were to determine if prenatal
earthquake exposure had an effect on EF, to determine how timing of exposure
influenced EF, if there were different EF outcomes for boys and girls, and how maternal
perceptions of severity influenced the child’s EF. Children from two groups (mothers
from Christchurch who experienced the earthquakes and mothers from Dunedin and
Timaru who did not) had their EF measured by a self-administered parent questionnaire,
the Behaviour Rating Inventory of Executive Function Second Edition (BRIEF 2).
Maternal demographics and earthquake severity experiences were gathered through a
second self-administered questionnaire. This study found that children who prenatally
experienced the earthquake had significantly worse scores on the measures of emotional
control and emotional regulation than the standardised average provided by the BRIEF
2. Exposure during the third trimester was associated with the most significant increases
in EF compared to children exposed during the second trimester and the standardised
average. In addition to emotional control and emotional regulation difficulties,
Christchurch boys also exhibited significantly higher scores on the Shift scale. Results
also showed that the worse someone close to the mother was injured, the higher the
child’s scores on the Inhibit, Organisation, and Emotional Control scale, and the
Behaviour Regulation index (BRI) were. Also, children of mothers who reported more
significantly injuring themselves in the earthquake had higher Emotional Regulation
(ERI) scores. Children whose mothers reported being overall extremely stressed by the
earthquake had the largest mean difference in emotional control and ERI scores
compared to the standardised average. Despite the small group sizes and continuing
aftershocks the variations in trimester and maternal perception of stress indicates that
prenatal exposure to a natural disaster does impact EF
Uniform in time estimates for the weak error of the Euler method for SDEs and a Pathwise Approach to Derivative Estimates for Diffusion Semigroups
We present a criterion for uniform in time convergence of the weak error of
the Euler scheme for Stochastic Differential equations (SDEs). The criterion
requires i) exponential decay in time of the space-derivatives of the semigroup
associated with the SDE and ii) bounds on (some) moments of the Euler
approximation. We show by means of examples (and counterexamples) how both i)
and ii) are needed to obtain the desired result. If the weak error converges to
zero uniformly in time, then convergence of ergodic averages follows as well.
We also show that Lyapunov-type conditions are neither sufficient nor necessary
in order for the weak error of the Euler approximation to converge uniformly in
time and clarify relations between the validity of Lyapunov conditions, i) and
ii).
Conditions for ii) to hold are studied in the literature. Here we produce
sufficient conditions for i) to hold. The study of derivative estimates has
attracted a lot of attention, however not many results are known in order to
guarantee exponentially fast decay of the derivatives. Exponential decay of
derivatives typically follows from coercive-type conditions involving the
vector fields appearing in the equation and their commutators; here we focus on
the case in which such coercive-type conditions are non-uniform in space. To
the best of our knowledge, this situation is unexplored in the literature, at
least on a systematic level. To obtain results under such space-inhomogeneous
conditions we initiate a pathwise approach to the study of derivative estimates
for diffusion semigroups and combine this pathwise method with the use of Large
Deviation Principles.Comment: 47 pages and 9 figure
New insights into the biomechanics of Legg-Calvé-Perthes’ disease: The role of epiphyseal skeletal immaturity in vascular obstruction
ObjectivesLegg–Calvé–Perthes’ disease (LCP) is an idiopathic osteonecrosis of the femoral head that is most common in children between four and eight years old. The factors that lead to the onset of LCP are still unclear; however, it is believed that interruption of the blood supply to the developing epiphysis is an important factor in the development of the condition.MethodsFinite element analysis modelling of the blood supply to the juvenile epiphysis was investigated to understand under which circumstances the blood vessels supplying the femoral epiphysis could become obstructed. The identification of these conditions is likely to be important in understanding the biomechanics of LCP.ResultsThe results support the hypothesis that vascular obstruction to the epiphysis may arise when there is delayed ossification and when articular cartilage has reduced stiffness under compression.ConclusionThe findings support the theory of vascular occlusion as being important in the pathophysiology of Perthes disease
Multiband radar characterization of forest biomes
The utility of airborne and orbital SAR in classification, assessment, and monitoring of forest biomes is investigated through analysis of orbital synthetic aperature radar (SAR) and multifrequency and multipolarized airborne SAR imagery relying on image tone and texture. Preliminary airborne SAR experiments and truck-mounted scatterometer observations demonstrated that the three dimensional structural complexity of a forest, and the various scales of temporal dynamics in the microwave dielectric properties of both trees and the underlying substrate would severely limit empirical or semi-empirical approaches. As a consequence, it became necessary to develop a more profound understanding of the electromagnetic properties of a forest scene and their temporal dynamics through controlled experimentation coupled with theoretical development and verification. The concatenation of various models into a physically-based composite model treating the entire forest scene became the major objective of the study as this is the key to development of a series of robust retrieval algorithms for forest biophysical properties. In order to verify the performance of the component elements of the composite model, a series of controlled laboratory and field experiments were undertaken to: (1) develop techniques to measure the microwave dielectric properties of vegetation; (2) relate the microwave dielectric properties of vegetation to more readily measured characteristics such as density and moisture content; (3) calculate the radar cross-section of leaves, and cylinders; (4) improve backscatter models for rough surfaces; and (5) relate attenuation and phase delays during propagation through canopies to canopy properties. These modeling efforts, as validated by the measurements, were incorporated within a larger model known as the Michigan Microwave Canopy Scattering (MIMICS) Model
Long-time behaviour of degenerate diffusions: UFG-type SDEs and time-inhomogeneous hypoelliptic processes
We study the long time behaviour of a large class of diffusion processes on
, generated by second order differential operators of (possibly)
degenerate type. The operators that we consider {\em need not} satisfy the
H\"ormander condition. Instead, they satisfy the so-called UFG condition,
introduced by Herman, Lobry and Sussman in the context of geometric control
theory and later by Kusuoka and Stroock, this time with probabilistic
motivations. In this paper we study UFG diffusions and demonstrate the
importance of such a class of processes in several respects: roughly speaking
i) we show that UFG processes constitute a family of SDEs which exhibit
multiple invariant measures and for which one is able to describe a systematic
procedure to determine the basin of attraction of each invariant measure
(equilibrium state). ii) We use an explicit change of coordinates to prove that
every UFG diffusion can be, at least locally, represented as a system
consisting of an SDE coupled with an ODE, where the ODE evolves independently
of the SDE part of the dynamics. iii) As a result, UFG diffusions are
inherently "less smooth" than hypoelliptic SDEs; more precisely, we prove that
UFG processes do not admit a density with respect to Lebesgue measure on the
entire space, but only on suitable time-evolving submanifolds, which we
describe. iv) We show that our results and techniques, which we devised for UFG
processes, can be applied to the study of the long-time behaviour of
non-autonomous hypoelliptic SDEs and therefore produce several results on this
latter class of processes as well. v) Because processes that satisfy the
(uniform) parabolic H\"ormander condition are UFG processes, our paper contains
a wealth of results about the long time behaviour of (uniformly) hypoelliptic
processes which are non-ergodic, in the sense that they exhibit multiple
invariant measures.Comment: 66 page
SIR-B measurements and modeling of vegetation
A summary is presented of the results derived from analysis of six SIR-B data takes over an agricultural test site in west central Illinois. The first part describes the procedure used to calibrate the SIR-B imagery, the second part pertains to the observed radar response to soil moisture content, and the last part examines the information derivable from multiangle observations
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