2,621 research outputs found
Scoring Play Combinatorial Games Under Different Operators
Scoring play games were first studied by Fraser Stewart for his PhD thesis.
He showed that under the disjunctive sum, scoring play games are partially
ordered, but do not have the same "nice" structure of normal play games. In
this paper I will be considering scoring play games under three different
operators given by John Conway and William Stromquist and David Ullman, namely
the conjunctive sum, selective sum and sequential join
Review of Low Carbon Communities:Imaginative Approaches to Combating Climate Change Locally by Michael Peters, Shane Fudge and Tim Jackson (eds).
Review of The geographies of garbage governance: interventions, interactions and outcomes by Anna R. Davies (2008).
Review of Recycling reconsidered: the present failure and future promise of environmental action in the United States by Samantha MacBride
Pituitary, ovarian and uterine function in dysfunctional uterine bleeding
This thesis describes a series of investigations of a
rather poorly defined group of menstrual disturbances known as
dysfunctional uterine bleeding (DUB). This condition is charact¬
erised by excessively heavy menstrual bleeding and, although
commoner at ages 30-50 years, may occur at any time during rep¬
roductive life. The large published literature has been thorough
ly reviewed and areas of ignorance highlighted.
The investigations described have been devised to elucidate
several aspects of pituitary, ovarian and uterine function in
women of different ages with ovulatory and anovulatory DUB and
compare these with normal women. All have raised questions req¬
uiring future study. The first section describes the use of a
combination of isotope dilution techniques and direct sampling
of ovarian venous blood and follicular fluid to study the ovar¬
ian blood flow and the ovarian secretion and metabolism of oestra
diol and oestrone in women with normal menstrual function or DUB.
In normal women 95% of circulating oestradiol was secreted by the
developing follicle or corpus luteum. In women with DUB oestro¬
gen metabolism was normal but the dynamics of oestrogen secretion
was sometimes disturbed. In some cases multiple follicle growth
and inappropriately high oestradiol secretion was observed. In
the follicular phase most large follicles were functionally
active and contained very high concentrations of oestradiol
(>1250 ng/ml).
Most adolescents with DUB are anovulatory and a very small
proportion develop the more extreme endometrial changes of cys¬
tic glandular hyperplasia (CGH). Follow up of the group of 17
of these adolescents over 10 years revealed a high incidence of
long term menstrual and reproductive disturbances. Detailed
endocrine assessment over 3 cycles in 4 young women with DUB &
CGH,and dynamic testing with oestrogen provocation and gonadotrophin-
releasing hormone stimulation in a further 9 young women
revealed a failure of positive oestrogen feedback as a cause
of the anovulation. All exhibited prolonged follicular activity
with, excessive oestradiol secretion.
A careful study of perception of menstrual bleeding indi¬
cated that many women perceived their menstrual blood loss to
be much heavier than objective measurements demonstrated. Only
38% of women with a convincing clinical history of menorrhagia
had a measured blood loss of greater than 80 mis. These women
also demonstrated some difficulty in assessing month to month
and even day to day changes in blood loss volume. In a differ¬
ent group of 28 women it was found that only 36% of the menstr¬
ual discharge (range 1.6-81.7%) consisted of blood, and the
remainder of the fluid is probably an endometrial transudate.
This may contribute to difficulties in perception.
The final section describes the development and application
of two inert gas clearance techniques (with Krypton-85 and
Kenon-J.33) for the measurement of endometrial blood flow (EBF)
in women. The techniques have been validated by comparison with
radioactive-labelled microspheres in sheep. Cyclical fluctua¬
tions in EBF were seen during the menstrual cycle with a pre¬
ovulatory peak, early luteal fall and gradual sustained rise up
to the onset of menses. The pattern was similar in ovulatory
DUB, while anovulatory women showed variable rates
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