410 research outputs found
Amino acid metabolism conflicts with protein diversity
The twenty protein coding amino acids are found in proteomes with different
relative abundances. The most abundant amino acid, leucine, is nearly an order
of magnitude more prevalent than the least abundant amino acid, cysteine. Amino
acid metabolic costs differ similarly, constraining their incorporation into
proteins. On the other hand, sequence diversity is necessary for protein
folding, function and evolution. Here we present a simple model for a
cost-diversity trade-off postulating that natural proteomes minimize amino acid
metabolic flux while maximizing sequence entropy. The model explains the
relative abundances of amino acids across a diverse set of proteomes. We found
that the data is remarkably well explained when the cost function accounts for
amino acid chemical decay. More than one hundred proteomes reach comparable
solutions to the trade-off by different combinations of cost and diversity.
Quantifying the interplay between proteome size and entropy shows that
proteomes can get optimally large and diverse
Shearson/American Express v. McMahon: The Expanding Scope of Securities Arbitration
Brokerage firms usually require that investors who open stock or commodities accounts execute a written customer agreement
Shadowing by non uniformly hyperbolic periodic points and uniform hyperbolicity
We prove that, under a mild condition on the hyperbolicity of its periodic
points, a map which is topologically conjugated to a hyperbolic map
(respectively, an expanding map) is also a hyperbolic map (respectively, an
expanding map). In particular, this result gives a partial positive answer for
a question done by A. Katok, in a related context
Polynomial-Time Amoeba Neighborhood Membership and Faster Localized Solving
We derive efficient algorithms for coarse approximation of algebraic
hypersurfaces, useful for estimating the distance between an input polynomial
zero set and a given query point. Our methods work best on sparse polynomials
of high degree (in any number of variables) but are nevertheless completely
general. The underlying ideas, which we take the time to describe in an
elementary way, come from tropical geometry. We thus reduce a hard algebraic
problem to high-precision linear optimization, proving new upper and lower
complexity estimates along the way.Comment: 15 pages, 9 figures. Submitted to a conference proceeding
Pregnant women\u27s knowledge of weight, weight gain, complications of obesity and weight management strategies in pregnancy
BACKGROUND: Obesity is increasingly common in the obstetric population. Maternal obesity and excess gestational weight gain (GWG) are associated with increased perinatal risk. There is limited published data demonstrating the level of pregnant women's knowledge regarding these problems, their consequences and management strategies.We aimed to assess the level of knowledge of pregnant women regarding: (i) their own weight and body mass index (BMI) category, (ii) awareness of guidelines for GWG, (iii) concordance of women's own expectations with guidelines, (iv) knowledge of complications associated with excess GWG, and (v) knowledge of safe weight management strategies in pregnancy. METHODS: 364 pregnant women from a single center university hospital antenatal clinic were interviewed by an obstetric registrar. The women in this convenience sample were asked to identify their weight category, their understanding of the complications of obesity and excessive GWG in pregnancy and safe and/or effective weight management strategies in pregnancy. RESULTS: Nearly half (47.8%) of the study population were overweight or obese. 74% of obese women underestimated their BMI category. 64% of obese women and 40% of overweight women overestimated their recommended GWG. Women's knowledge of the specific risks associated with excess GWG or maternal obesity was poor. Women also reported many incorrect beliefs about safe weight management in pregnancy. CONCLUSIONS: Many pregnant women have poor knowledge about obesity, GWG, their consequences and management strategies. Bridging this knowledge gap is an important step towards improving perinatal outcomes for all pregnant women, especially those who enter pregnancy overweight or obese
The multipliers of periodic points in one-dimensional dynamics
It will be shown that the smooth conjugacy class of an unimodal map which
does not have a periodic attractor neither a Cantor attractor is determined by
the multipliers of the periodic orbits. This generalizes a result by M.Shub and
D.Sullivan for smooth expanding maps of the circle
Simultaneous Continuation of Infinitely Many Sinks Near a Quadratic Homoclinic Tangency
We prove that the diffeomorphisms on surfaces, exhibiting infinitely
many sinksnear the generic unfolding of a quadratic homoclinic tangency of a
dissipative saddle, can be perturbed along an infinite dimensional manifold of
diffeomorphisms such that infinitely many sinks persist simultaneously.
On the other hand, if they are perturbed along one-parameter families that
unfold generically the quadratic tangencies, then at most a finite number of
those sinks have continuation
Gestational weight gain information: seeking and sources among pregnant women
BACKGROUND: Promoting healthy gestational weight gain (GWG) is important for preventing obstetric and perinatal morbidity, along with obesity in both mother and child. Provision of GWG guidelines by health professionals predicts women meeting GWG guidelines. Research concerning women\u27s GWG information sources is limited. This study assessed pregnant women\u27s sources of GWG information and how, where and which women seek GWG information. METHODS: Consecutive women (n = 1032) received a mailed questionnaire after their first antenatal visit to a public maternity hospital in Melbourne, Australia. Recalled provision of GWG guidelines by doctors and midwives, recalled provided GWG goals, and the obtaining of GWG information and information sources were assessed. RESULTS: Participants (n = 368; 35.7 % response) averaged 32.5 years of age and 20.8 weeks gestation, with 33.7 % speaking a language other than English. One in ten women recalled receiving GWG guidelines from doctors or midwives, of which half were consistent with Institute of Medicine guidelines. More than half the women (55.4 %) had actively sought GWG information. Nulliparous (OR 7.07, 95 % CI = 3.91-12.81) and obese (OR 1.96, 95 % CI = 1.05-3.65) women were more likely to seek information. Underweight (OR 0.29, 95 % CI = 0.09-0.97) women and those working part time (OR 0.52, 95 % CI = 0.28-0.97) were less likely to seek information. Most frequently reported GWG sources included the internet (82.7 %), books (55.4 %) and friends (51.5 %). The single most important sources were identified as the internet (32.8 %), general practitioners (16.9 %) and books (14.9 %). CONCLUSION: More than half of women were seeking GWG guidance and were more likely to consult non-clinician sources. The small numbers given GWG targets, and the dominance of non-clinical information sources, reinforces that an important opportunity to provide evidence based advice and guidance in the antenatal care setting is currently being missed
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