5,299 research outputs found
Forest diagrams for elements of Thompson's group F
We introduce forest diagrams to represent elements of Thompson's group F.
These diagrams relate to a certain action of F on the real line in the same way
that tree diagrams relate to the standard action of F on the unit interval.
Using forest diagrams, we give a conceptually simple length formula for
elements of F with respect to the {x_0,x_1} generating set, and we discuss the
construction of minimum-length words for positive elements. Finally, we use
forest diagrams and the length formula to examine the structure of the Cayley
graph of F.Comment: 44 pages, 70 figure
An inverse source problem for the heat equation and the enclosure method
An inverse source problem for the heat equation is considered. Extraction
formulae for information about the time and location when and where the unknown
source of the equation firstly appeared are given from a single lateral
boundary measurement. New roles of the plane progressive wave solutions or
their complex versions for the backward heat equation are given.Comment: 23page
The Age Dependent Luminosities of the Red Giant Branch Bump, Asymptotic Giant Branch Bump, and Horizontal Branch Red Clump
Color-magnitude diagrams of globular clusters often exhibit a prominent
horizontal branch (HB) and may also show features such as the red giant branch
(RGB) bump and the asymptotic giant branch (AGB) bump. Stellar evolution theory
predicts that the luminosities of these features will depend on the metallicity
and age of the cluster. We calculate theoretical lines of 2 to 12 Gyr constant
age RGB-bumps and AGB-bumps in the V(HB-Bump)--[Fe/H] diagram, which shows the
brightness difference between the bump and the HB as a function of metallicity.
In order to test the predictions, we identify giant branch bumps in new Hubble
Space Telescope color-magnitude diagrams for 8 SMC clusters. First, we conclude
that the SMC cluster bumps are RGB-bumps. The data for clusters younger than ~6
Gyr are in fair agreement the relative age dependent luminosities of the HB and
RGB-bump. The V(HB-Bump)--[Fe/H] data for clusters older then ~6 Gyr
demonstrate a less satisfactory agreement with our calculations. We conclude
that ~6 Gyr is a lower bound to the age of clusters for which the Galactic
globular cluster, age independent V(HB-Bump)--[Fe/H] calibration is valid.
Application of the V(HB-bump)--[Fe/H] diagram to stellar population studies is
discussed.Comment: Accepted for publication in the Astrophysical Journal, 30 pages,
Latex aaspp4.sty, including 7 postscript figure
Elementary amenable subgroups of R. Thompson's group F
The subgroup structure of Thompson's group F is not yet fully understood. The
group F is a subgroup of the group PL(I) of orientation preserving, piecewise
linear self homeomorphisms of the unit interval and this larger group thus also
has a poorly understood subgroup structure. It is reasonable to guess that F is
the "only" subgroup of PL(I) that is not elementary amenable. In this paper, we
explore the complexity of the elementary amenable subgroups of F in an attempt
to understand the boundary between the elementary amenable subgroups and the
non-elementary amenable. We construct an example of an elementary amenable
subgroup up to class (height) omega squared, where omega is the first infinite
ordinal.Comment: 20 page
Nitrogen-grafted activated carbon for removing nitrate from water
Nitrate (NO3~) and nitrite (NO2~) ions are ubiquitous in the environment and considered
hazardous to humans. The primary health hazard from drinking water containing NO3~ occurs when it
is transformed to NO2~ in the digestive system (Robillard et al., 2006). Currently nitrate is removed from
water using polymer anion exchangers. However, this process is expensive and requires a lot of brine
(NaCl) for the exchanger regeneration. Alternative physicochemical methods such as reverse osmosis are
expensive and inefficient.
The proposed research aims to develop anion-selective nitrogen-containing activated carbon, NGAC
that can be regenerated electrochemically and does not require concentrated brine for regeneration. The
key to the selectivity of the NGAC is achieved by the deposition of N-bearing conductive polymers or
other species such as polypyrrole, polyaniline, pyridinium, quaternary ammonium, etc. onto the AC
surface. Our preliminary results indicate that the polypyrrole charge can remain stable through multiple
redox cycles (at least 50)
Phase Diagram of One-Dimensional Extended Hubbard Model at Half Filling
We reexamine the ground-state phase diagram of the one-dimensional
half-filled Hubbard model with on-site and nearest-neighbor repulsive
interactions. We calculate second-order corrections to coupling constants in
the g-ology to show that the bond-charge-density-wave (BCDW) phase exists for
weak couplings in between the charge density wave (CDW) and spin density wave
(SDW) phases. We find that the umklapp scattering of parallel-spin electrons
destabilizes the BCDW state and gives rise to a bicritical point where the
CDW-BCDW and SDW-BCDW continuous-transition lines merge into the CDW-SDW
first-order transition line.Comment: 4 pages, 3 figure
A review of breeding objectives, genomic resources, and marker-assisted methods in common bean (Phaseolus vulgaris L.)
Common bean (Phaseolus vulgaris L.), one of the most important grain legume crops for direct human consumption, faces many challenges as a crop. Domesticated from wild relatives that inhabit a relatively narrow ecological niche, common bean faces a wide range of biotic and abiotic constraints within its diverse agroecological settings. Biotic stresses impacting common bean include numerous bacterial, fungal, and viral diseases and various insect and nematode pests, and abiotic stresses include drought, heat, cold, and soil nutrient deficiencies or toxicities. Breeding is often local, focusing on improvements in responses to biotic and abiotic stresses that are particular challenges in certain locations and needing to respond to conditions such as day-length regimes. This review describes the major breeding objectives for common bean, followed by a description of major genetic and genomic resources, and an overview of current and prospective marker-assisted methods in common bean breeding. Improvements over traditional breeding methods in CB can result from the use of different approaches. Several important germplasm collections have been densely genotyped, and relatively inexpensive SNP genotyping platforms enable implementation of genomic selection and related marker-assisted breeding approaches. Also important are sociological insights related to demand-led breeding, which considers local value chains, from farmers to traders to retailers and consumers
Cohesion, team mental models, and collective efficacy: Towards an integrated framework of team dynamics in sport
A nomological network on team dynamics in sports consisting of a multi-framework perspective is introduced and tested. The aim was to explore the interrelationship among cohesion, team mental models (TMM), collective-efficacy (CE), and perceived performance potential (PPP). Three hundred and forty college-aged soccer players representing 17 different teams (8 female and 9 male) participated in the study. They responded to surveys on team cohesion, TMM, CE and PPP. Results are congruent with the theoretical conceptualization of a parsimonious view of team dynamics in sports. Specifically, cohesion was found to be an exogenous variable predicting both TMM and CE beliefs. TMM and CE were correlated and predicted PPP, which in turn accounted for 59% of the variance of objective performance scores as measured by teams’ season record. From a theoretical standpoint, findings resulted in a parsimonious view of team dynamics, which may represent an initial step towards clarifying the epistemological roots and nomological network of various team-level properties. From an applied standpoint, results suggest that team expertise starts with the establishment of team cohesion. Following the establishment of cohesiveness, teammates are able to advance team-related schemas and a collective sense of confidence. Limitations and key directions for future research are outlined
Use of Non-Steroidal Anti-Inflammatory Drugs That Elevate Cardiovascular Risk: An Examination of Sales and Essential Medicines Lists in Low-, Middle-, and High-Income Countries
PMCID: PMC3570554This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
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