2,008 research outputs found
Preventing children's involvement in crime and anti-social behaviour : a literature review : a paper produced for the National Evaluation of the Children's Fund
Large Scale Features of Rotating Forced Turbulence
Large scale features of a randomly isotropically forced incompressible and
unbounded rotating fluid are examined in perturbation theory. At first order in
both the random force amplitude and the angular velocity we find two types of
modifications to the fluid equation of motion. The first correction transforms
the molecular shear viscosity into a (rotation independent) effective
viscosity. The second perturbative correction leads to a new large scale
non-dissipative force proportional to the fluid angular velocity in the slow
rotation regime. This effective force does no net work and alters the
dispersion relation of inertial waves propagating in the fluid. Both
dynamically generated corrections can be identified with certain components of
the most general axisymmetric ``viscosity tensor'' for a Newtonian fluid.Comment: 12 pages, 2 figures, RevTeX, and accepted for publication in Phys.
Rev.
An Evaluation of the effectiveness of systematic desensitization for the modification of cigarette smoking
Relation between obesity and the oestrogen receptor status of breast cancer
Introduction: Obesity is a growing problem in the Western world. Correlations have been found between increasing body mass index (BMI) and breast cancer. The objectives were to establish whether a relationship exists between BMI and breast cancer and to investigate any association between BMI and tumour oestrogen receptor expression.
Method: Clinical and socio-demographic details (age, menopausal status, height and weight) of a sample of women with breast cancer operated in 2010 were collected, dividing the group into oestrogen receptor positive (ER+) and negative (ER–) subgroups. The average BMI of each subgroup was compared to the mean BMI of a sample of the general Maltese female population obtained from the European Health Examination Survey 2010 Report (Pilot Study) by virtue of an ANOVA test. Subsequently, the relations between oestrogen receptor expression and each of menopausal status, age and BMI were statistically analysed using chi-squared analysis and two-sample t-tests.
Results: A total of 103 patients were studied. 72 patients (age range: 40 – 90 years) had ER+ malignancy and 31 patients (29 – 81 years) had ER- malignancy. The mean BMI’s of the ER+ and ER- subgroups were 30.1 and 27.1 respectively, while that of the female general population (29 – 90 years) was 28.4. Analysis revealed a significant difference between the BMI’s of the ER+ and ER- subgroups (p<0.05) but no difference between each receptor subgroup and the general population. Neither menopausal status nor age was found to correlate with positive oestrogen receptor expression.
Conclusions: Women with ER+ malignancy tended to be significantly more obese than those with ER- breast cancer. However, neither subgroup had a mean BMI significantly different from that of the general population.peer-reviewe
Every countable model of set theory embeds into its own constructible universe
The main theorem of this article is that every countable model of set theory
M, including every well-founded model, is isomorphic to a submodel of its own
constructible universe. In other words, there is an embedding that
is elementary for quantifier-free assertions. The proof uses universal digraph
combinatorics, including an acyclic version of the countable random digraph,
which I call the countable random Q-graded digraph, and higher analogues
arising as uncountable Fraisse limits, leading to the hypnagogic digraph, a
set-homogeneous, class-universal, surreal-numbers-graded acyclic class digraph,
closely connected with the surreal numbers. The proof shows that contains
a submodel that is a universal acyclic digraph of rank . The method of
proof also establishes that the countable models of set theory are linearly
pre-ordered by embeddability: for any two countable models of set theory, one
of them is isomorphic to a submodel of the other. Indeed, they are
pre-well-ordered by embedability in order-type exactly .
Specifically, the countable well-founded models are ordered by embeddability in
accordance with the heights of their ordinals; every shorter model embeds into
every taller model; every model of set theory is universal for all
countable well-founded binary relations of rank at most ; and every
ill-founded model of set theory is universal for all countable acyclic binary
relations. Finally, strengthening a classical theorem of Ressayre, the same
proof method shows that if is any nonstandard model of PA, then every
countable model of set theory---in particular, every model of ZFC---is
isomorphic to a submodel of the hereditarily finite sets of . Indeed,
is universal for all countable acyclic binary relations.Comment: 25 pages, 2 figures. Questions and commentary can be made at
http://jdh.hamkins.org/every-model-embeds-into-own-constructible-universe.
(v2 adds a reference and makes minor corrections) (v3 includes further
changes, and removes the previous theorem 15, which was incorrect.
Renormalization Group Improving the Effective Action
The existence of fluctuations together with interactions leads to
scale-dependence in the couplings of quantum field theories for the case of
quantum fluctuations, and in the couplings of stochastic systems when the
fluctuations are of thermal or statistical nature. In both cases the effects of
these fluctuations can be accounted for by solutions of the corresponding
renormalization group equations. We show how the renormalization group
equations are intimately connected with the effective action: given the
effective action we can extract the renormalization group equations; given the
renormalization group equations the effects of these fluctuations can be
included in the classical action by using what is known as improved
perturbation theory (wherein the bare parameters appearing in tree-level
expressions are replaced by their scale-dependent running forms). The improved
action can then be used to reconstruct the effective action, up to finite
renormalizations, and gradient terms.Comment: 25 pages, ReV-TeX 3.
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