434 research outputs found
Graph Treewidth and Geometric Thickness Parameters
Consider a drawing of a graph in the plane such that crossing edges are
coloured differently. The minimum number of colours, taken over all drawings of
, is the classical graph parameter "thickness". By restricting the edges to
be straight, we obtain the "geometric thickness". By further restricting the
vertices to be in convex position, we obtain the "book thickness". This paper
studies the relationship between these parameters and treewidth.
Our first main result states that for graphs of treewidth , the maximum
thickness and the maximum geometric thickness both equal .
This says that the lower bound for thickness can be matched by an upper bound,
even in the more restrictive geometric setting. Our second main result states
that for graphs of treewidth , the maximum book thickness equals if and equals if . This refutes a conjecture of Ganley and
Heath [Discrete Appl. Math. 109(3):215-221, 2001]. Analogous results are proved
for outerthickness, arboricity, and star-arboricity.Comment: A preliminary version of this paper appeared in the "Proceedings of
the 13th International Symposium on Graph Drawing" (GD '05), Lecture Notes in
Computer Science 3843:129-140, Springer, 2006. The full version was published
in Discrete & Computational Geometry 37(4):641-670, 2007. That version
contained a false conjecture, which is corrected on page 26 of this versio
âBecause itâs our culture!â (Re)negotiating the meaning of lobola in Southern African secondary schools
Payment of bridewealth or lobola is a significant element of marriage among the Basotho of Lesotho and the Shona of Zimbabwe. However, the functions and meanings attached to the practice are constantly changing. In order to gauge the interpretations attached to lobola by young people today, this paper analyses a series of focus group discussions conducted among senior students at two rural secondary schools. It compares the interpretations attached by the students to the practice of lobola with academic interpretations (both historical and contemporary). Among young people the meanings and functions of lobola are hotly contested, but differ markedly from those set out in the academic literature. While many students see lobola as a valued part of âAfrican cultureâ, most also view it as a financial transaction which necessarily disadvantages women. The paper then seeks to explain the young peopleâs interpretations by reference to discourses of âequal rightsâ and âcultureâ prevalent in secondary schools. Young people make use of these discourses in (re)negotiating the meaning of lobola, but the limitations of the discourses restrict the interpretations of lobola available to them
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A randomised controlled trial of treatments of childhood anxiety disorder in the context of maternal anxiety disorder: clinical and cost-effectiveness outcomes
Background: This study evaluated whether clinical and economic outcomes from CBT for child anxiety disorders in the context of maternal anxiety disorders are improved by adding treatment focused on (i) maternal anxiety disorders, or (ii) mother-child interactions. Methods: 211 children (7 â 12 years, 85% White British, 52% female) with a primary anxiety disorder, whose mothers also had a current anxiety disorder, were randomised to receive (i) child-focused CBT with non-specific control interventions (CCBT+Con), (ii) CCBT with CBT for the maternal anxiety disorder (CCBT+MCBT), or (iii) CCBT with an intervention targeting the mother-child interaction (CCBT+MCI). A cost-utility analysis from a societal perspective was conducted using mother/child combined Quality Adjusted Life Years (QALYs). [Trial registration: https://doi.org/10.1186/ISRCTN19762288]. Results: MCBT was associated with immediate reductions in maternal anxiety compared to the non-specific control; however, after children had also received CCBT, maternal outcomes in the CCBT+MCI and CCBT+Con arms improved and CCBT+MCBT was no longer superior. Neither CCBT+MCBT nor CCBT+MCI conferred a benefit over CCBT+Con in terms of child anxiety disorder diagnoses post-treatment [primary outcome] (adj RR: 1.22 (95% CI 0.88, 1.67), p = .23; adj RR: 1.21 (95% CI 0.88, 1.65), p = .24 respectively) or global improvement ratings (adj RR 1.25 (95% CI 0.99, 1.57), p = .06; adj RR 1.18 (95% CI 0.93, 1.50), p = .17) or six and 12 months later. No significant differences between the groups were found on the main economic outcome measures (child/mother combined QALY mean difference: CCBT+MCBT vs CCBT+Con: -0.04 (95% CI -0.12, 0.04), p = 0.29; CCBT+MCI vs CCBT+Con: 0.02 (95% CI -0.05, -0.09), p = 0.54). CCBT+MCI was associated with non-significantly higher costs than CCBT (mean difference: ÂŁ154 (95% CI -ÂŁ1239, ÂŁ1547), p = 0.83) but, when taking into account sampling uncertainty, it may be cost-effective compared with CCBT alone. Conclusions: Good outcomes were achieved for children and their mothers across treatment arms. There was no evidence of significant clinical benefit from supplementing CCBT with either CBT for the maternal anxiety disorder or treatment focussed on mother-child interactions, but the addition of MCI (and not MCBT) may be cost-effective. Keywords: Child; anxiety; mother; parent-child interaction; CBT
Quark-Squark Alignment Revisited
We re-examine the possibility that the solution to the supersymmetric flavor
problem is related to small mixing angles in gaugino couplings induced by
approximate horizontal Abelian symmetries. We prove that, for a large class of
models, there is a single viable structure for the down quark mass matrix with
four holomorphic zeros. Consequently, we are able to obtain both lower and
upper bounds on the supersymmetric mixing angles and predict the contributions
to various flavor changing neutral current processes. We find that the most
likely signals for alignment are close to the present bound,
significant CP violation in mixing, and shifts of order a few
percent in various CP asymmetries in and decays. In contrast, the
modifications to radiative B decays, to and to
decays are small. We further investigate a new class of
alignment models, where supersymmetric contributions to flavor changing
processes are suppressed by both alignment and RGE-induced degeneracy.Comment: 20 pages, 3 figure
âItâs my dream to work with Olympic athletesâ: Neophyte sport psychologistsâ expectations and initial experiences regarding service delivery
We examined trainee practitioners' initial experiences of applied sport psychology practice. Semi-structured interviews (4) were conducted over 6 months with 7 full-time MSc students before, during, and after the applied sport psychology module, when they were working with clients. Participants also kept reflective diaries over an 8-week period whilst working with clients. Findings included: (a) motivations and expectations of an ASP practice career, (b) perceptions of service delivery, (c) emotional demands, and (d) pivotal experiences. Findings extend previous literature on the initial stages of practitioner development, providing micro-level detail on aspects of the intense development process during this pivotal perio
Adjoint bulk scalars and supersymmetric unification in the presence of extra dimensions
There are several advantages of introducing adjoint superfields at
intermediate energies around GeV. Such as (i) gauge couplings still
unify (ii) neutrino masses and mixings are produced (iii) primordial lepton
asymmetry can be produced. We point out that if adjoint scalars have bulk
excitations along with gauge bosons whereas fermions and the doublet scalar
live on boundary then N=2 supersymmetric beta functions vanish.
Thus even if extra dimensions open up at an intermediate scale and all
N=2 Yang-Mills fields as well as N=2 matter fields in the adjoint
representation propagate in the bulk, still gauge couplings renormalize beyond
just like they do in 4-dimensions with adjoint scalars. Consequently
unification is achieved in the presence to extra dimensions, mass scales are
determined uniquely via Renormalization Group Equations(RGE) and unification
scale remains high enough to suppress proton decay. This scenario can be
falsified if we get signatures of extra dimensions at low energy.Comment: New references added. This version will appear in Phys. Rev.
Bottom Production
We review the prospects for bottom production physics at the LHC.Comment: 74 pages, Latex, 71 figures, to appear in the Report of the ``1999
CERN Workshop on SM physics (and more) at the LHC'', P. Nason, G. Ridolfi, O.
Schneider G.F. Tartarelli, P. Vikas (conveners
Democracy and governance networks: compatible or not?
The relationship between representative democracy and governance networks is investigated
at a theoretical level. Four conjectures about the relationship are defined. The
incompatibility conjectures rests on the primacy of politics and sees governance networks as a
threat. The complementarity conjecture presents governance networks as a means of enabling
greater participation in the policy process and sensitivity in programme implementation. The
transitional conjecture posits a wider evolution of governance forms towards network
relationships. The instrumental conjecture views governance networks as a powerful means
through which dominant interests can achieve their goals. Illustrative implications for theory
and practice are identified, in relation to power in the policy process, the public interest, and
the role of public managers. The heuristic potential of the conjectures is demonstrated
through the identification of an outline research agenda
Amine Containing Analogs of Sulindac for Cancer Prevention
Background:
Sulindac belongs to the chemically diverse family of Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) that effectively prevent adenomatous colorectal polyps and colon cancer, especially in patients with familial adenomatous polyposis. Sulindac sulfide amide (SSA), an amide analog of sulindac sulfide, shows insignificant COX-related activity and toxicity while enhancing anticancer activity in vitro and demonstrating in vivo xenograft activity.
Objective:
Develop structure-activity relationships in the sulindac amine series and identify analogs with promising anticancer activities.
Method:
A series of sulindac amine analogs were designed and synthesized and then further modified in a âlibraries from librariesâ approach to produce amide, sulfonamide and N,N-disubstituted sulindac amine sub-libraries. All analogs were screened against three cancer cell lines (prostate, colon and breast).
Results:
Several active compounds were identified viain vitro cancer cell line screening with the most potent compound (26) in the nanomolar range.
Conclusion:
Compound 26 and analogs showing the most potent inhibitory activity may be considered for further design and optimization efforts as anticancer hit scaffolds
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