588 research outputs found
The stratigraphy, correlation, provenance and palaeogeography of the Skiddaw Group (Ordovician) in the English Lake District
A new lithostratigraphy is presented for the Skiddaw Group (lower Ordovician) of the English Lake District. Two stratigraphical belts are described. Five formations are defined in the Northern Fells Belt, ranging in age from Tremadoc to early Llanvirn. They are all mudstone or sandstone dominated, of turbidite origin; in ascending order they are named the Bitter Beck, Watch Hill, Hope Beck, Loweswater and Kirk Stile formations. Two formations are defined in the Central Fells Belt, ranging in age from late Arenig to Llanvirn. These are the Buttermere Formation - a major olistostrome deposit - overlain by the Tarn Moor Formation, consisting of turbidite mudstones with volcaniclastic turbidite sandstone beds. A revised graptolite and new acritarch biostratigraphy for the Skiddaw Group is presented with eight graptolite biozones and thirteen acritarch assemblages and sub-assemblages. The provenance of the group is assessed from detailed petrographical and geochemical work. This suggests derivation, in the early Ordovician, largely from an old inactive continental arc terrane lying to the south-east, with the appearance of juvenile volcanic material in the Llanvirn. Comparisons and correlations of the Skiddaw Group are made with the Isle of Man and eastern Ireland
Feasibility of a community healthy eating and cooking intervention featuring traditional African Caribbean foods from participant and staff perspectives
Culturally appropriate healthy eating resources are intended to help people from different ethnic backgrounds consume diets reflecting government dietary recommendations, yet evidence on use in the target groups is lacking. This study evaluated the feasibility of a new brief culturally appropriate community intervention that aimed to introduce food-based healthy eating and recipe resources featuring African Caribbean foods, which were recently co-developed with people from these ethnic backgrounds. Working with a community organization in the UK, a single-arm study was used to collect verbal data from participants and staff on the acceptability of intervention whilst knowledge, skills and behaviours related to healthy eating were evaluated using pre-, post- and follow-up questionnaires. A total of 30 participants were recruited, and 22 completed all three questionnaires; who were mostly female aged 55 years+ (n = 17) and of African Caribbean ethnicity (45%, n = 10), with 32% (n = 7) reporting no educational attainment. At post-intervention and follow-up, most participants reported high satisfaction (n = 21, 95%) with the intervention sessions and high levels of confidence in using the resources at home within budget. The number of participants who were familiar with the healthy eating guidance featuring Caribbean foods increased from pre- (36%, n = 8) to post-intervention/follow-up (n = 22, 100%) (p < 0.05). Findings suggest the intervention is feasible in a community setting and could help increase awareness and use of culturally appropriate healthy eating guidance amongst a diverse group
Spinons and parafermions in fermion cosets
We introduce a set of gauge invariant fermion fields in fermionic coset
models and show that they play a very central role in the description of
several Conformal Field Theories (CFT's). In particular we discuss the explicit
realization of primaries and their OPE in unitary minimal models, parafermion
fields in CFT's and that of spinon fields in
Wess-Zumino-Witten models (WZW) theories. The higher level case () will be
briefly discussed. Possible applications to QHE systems and spin-ladder systems
are addressed.Comment: 6 pages, Latex file. Invited talk at International Seminar dedicated
to the memory of D.V.Volkov, Kharkov, January 5-7, 199
Multidimensional continued fractions, dynamical renormalization and KAM theory
The disadvantage of `traditional' multidimensional continued fraction
algorithms is that it is not known whether they provide simultaneous rational
approximations for generic vectors. Following ideas of Dani, Lagarias and
Kleinbock-Margulis we describe a simple algorithm based on the dynamics of
flows on the homogeneous space SL(2,Z)\SL(2,R) (the space of lattices of
covolume one) that indeed yields best possible approximations to any irrational
vector. The algorithm is ideally suited for a number of dynamical applications
that involve small divisor problems. We explicitely construct renormalization
schemes for (a) the linearization of vector fields on tori of arbitrary
dimension and (b) the construction of invariant tori for Hamiltonian systems.Comment: 51 page
Automorphism Modular Invariants of Current Algebras
We consider those two-dimensional rational conformal field theories (RCFTs)
whose chiral algebras, when maximally extended, are isomorphic to the current
algebra formed from some affine non-twisted Kac--Moody algebra at fixed level.
In this case the partition function is specified by an automorphism of the
fusion ring and corresponding symmetry of the Kac--Peterson modular matrices.
We classify all such partition functions when the underlying finite-dimensional
Lie algebra is simple. This gives all possible spectra for this class of RCFTs.
While accomplishing this, we also find the primary fields with second smallest
quantum dimension.Comment: 32 pages, plain Te
Fractional Quantum Hall Effect via Holography: Chern-Simons, Edge States, and Hierarchy
We present three holographic constructions of fractional quantum Hall effect
(FQHE) via string theory. The first model studies edge states in FQHE using
supersymmetric domain walls in N=6 Chern-Simons theory. We show that D4-branes
wrapped on CP^1 or D8-branes wrapped on CP^3 create edge states that shift the
rank or the level of the gauge group, respectively. These holographic edge
states correctly reproduce the Hall conductivity. The second model presents a
holographic dual to the pure U(N)_k (Yang-Mills-)Chern-Simons theory based on a
D3-D7 system. Its holography is equivalent to the level-rank duality, which
enables us to compute the Hall conductivity and the topological entanglement
entropy. The third model introduces the first string theory embedding of
hierarchical FQHEs, using IIA string on C^2/Z_n.Comment: 36 pages, 6 figures; v2: with an improved derivation of Hall
conductivity in section 3.2, typo corrections, and additional references; v3:
explanations and comments adde
Nearest Neighbor Distances on a Circle: Multidimensional Case
We study the distances, called spacings, between pairs of neighboring energy
levels for the quantum harmonic oscillator. Specifically, we consider all
energy levels falling between E and E+1, and study how the spacings between
these levels change for various choices of E, particularly when E goes to
infinity. Primarily, we study the case in which the spring constant is a badly
approximable vector. We first give the proof by Boshernitzan-Dyson that the
number of distinct spacings has a uniform bound independent of E. Then, if the
spring constant has components forming a basis of an algebraic number field, we
show that, when normalized up to a unit, the spacings are from a finite set.
Moreover, in the specific case that the field has one fundamental unit, the
probability distribution of these spacings behaves quasiperiodically in log E.
We conclude by studying the spacings in the case that the spring constant is
not badly approximable, providing examples for which the number of distinct
spacings is unbounded.Comment: Version 2 is updated to include more discussion of previous works. 17
pages with five figures. To appear in the Journal of Statistical Physic
Three Drinking-Water–Associated Cryptosporidiosis Outbreaks, Northern Ireland
Three recent drinking-water–associated cryptosporidiosis outbreaks in Northern Ireland were investigated by using genotyping and subgenotyping tools. One Cryptosporidium parvum outbreak was caused by the bovine genotype, and two were caused by the human genotype. Subgenotyping analyses indicate that two predominant subgenotypes were associated with these outbreaks and had been circulating in the community
Evaluation of delayed timing of artificial insemination with sex-sorted sperm on pregnancy per artificial insemination in seasonal-calving, pasture-based lactating dairy cows
peer-reviewedThe objective was to use ovulation synchronization with timed artificial insemination (TAI) to evaluate the effect of timing of artificial insemination (AI) with frozen sex-sorted sperm on fertility performance in pasture-based compact calving herds. Ejaculates from 3 Holstein-Friesian bulls were split and processed to provide frozen sex-sorted sperm (SS) at 4 × 106 sperm per straw, and frozen conventional sperm at 15 × 106 sperm per straw (CONV). A modified Progesterone-Ovsynch protocol was used for estrous synchronization, with TAI occurring 16 h after the second GnRH injection for cows assigned to CONV, and either 16 h (SS-16) or 22 h (SS-22) for cows assigned to SS. Pregnancy diagnosis was conducted by transrectal ultrasound scanning of the uterus 35 to 40 d after TAI (n = 2,175 records available for analysis). Generalized linear mixed models were used to examine the effects of treatment on pregnancy per artificial insemination (P/AI). Fixed effects included treatment (n = 3), bull (n = 3), treatment by bull interaction, parity (n = 4), days-in-milk category (n = 3), and treatment by days-in-milk category, with herd (n = 24) included as a random effect. Pregnancy per AI was greater for CONV compared with both SS-16 and SS-22 (61.1%, 49.0%, and 51.3%, respectively), and the SS treatments did not differ from each other (relative P/AI for SS-16 and SS-22 vs. CONV were 80.2% and 84.0%, respectively). There were significant bull and treatment by bull interaction effects. Additional analysis was undertaken using a model that included herd as a fixed effect. This analysis identified marked herd-to-herd variation (within-herd relative P/AI for the combined SS treatments vs. CONV ranged from 48–121%). The tertile of herds with the best performance achieved a mean relative P/AI of 100% (range = 91–121%), indicating that P/AI equivalent to CONV is achievable with SS. Conversely, the tertile of herds with the poorest performance achieved a mean relative P/AI of 67% (range = 48–77%). We found that SS resulted in poorer overall P/AI compared with CONV sperm regardless of timing of AI. Marked variation existed between herds; however, one-third of herds achieved P/AI results equal to CONV. Identification of factors responsible for the large herd-to-herd variation in P/AI with SS, and development of strategies to reduce this variation, warrant further research
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