711 research outputs found
Estimating age-specific fertility rates by ethnic group for population projections
Population projections with an ethnic group dimension can inform the provision of relevant goods and services, such as appropriate housing and language support, and can help set targets for take-up of equal opportunities. Projections by ethnic group can also inform policy debates on international migration and diversity. To understand past population change by ethnic group and to inform projections of future populations we need demographic rates appropriate to each ethnic group. Whilst estimates of ethnic-specific migration and mortality rates have been calculated here we focus on data sources which can help us understand fertility trends by ethnic group
The Neuroanatomical Organization of Projection Neurons Associated with Different Olfactory Bulb Pathways in the Sea Lamprey, Petromyzon marinus
Although there is abundant evidence for segregated processing in the olfactory system across vertebrate taxa, the spatial relationship between the second order projection neurons (PNs) of olfactory subsystems connecting sensory input to higher brain structures is less clear. In the sea lamprey, there is tight coupling between olfaction and locomotion via PNs extending to the posterior tuberculum from the medial region of the olfactory bulb. This medial region receives peripheral input predominantly from the accessory olfactory organ. However, the axons from olfactory sensory neurons residing in the main olfactory epithelium extend to non-medial regions of the olfactory bulb, and the non-medial bulbar PNs extend their axons to the lateral pallium. It is not known if the receptive fields of the PNs in the two output pathways overlap; nor has the morphology of these PNs been investigated. In this study, retrograde labelling was utilized to investigate the PNs belonging to medial and non-medial projections. The dendrites and somata of the medial PNs were confined to medial glomerular neuropil, and dendrites of non-medial PNs did not enter this territory. The cell bodies and dendrites of the non-medial PNs were predominantly located below the glomeruli (frequently deeper in the olfactory bulb). While PNs in both locations contained single or multiple primary dendrites, the somal size was greater for medial than for non-medial PNs. When considered with the evidence-to-date, this study shows different neuroanatomical organization for medial olfactory bulb PNs extending to locomotor control centers and non-medial PNs extending to the lateral pallium in this vertebrate
Equine meniscal degeneration is associated with medial femorotibial osteoarthritis
Background: There is limited information available concerning normal equine meniscal morphology, its degeneration and role in osteoarthritis (OA).
Objectives: To characterise normal equine meniscal morphology and lesions and to explore the relationship between equine meniscal degeneration and femorotibial OA.
Study design: Ex vivo cadaveric study.
Methods: Menisci were harvested from 7 normal joints (n = 14 menisci) and 15 joints with OA (n = 30 menisci). A macroscopic femorotibial OA score (cartilage degeneration and osteophytosis) was employed to measure disease severity in each compartment. The femoral and tibial meniscal surfaces were scored for macroscopic fibrillation and tears (1–4). Histological sections (regions: cranial and caudal horn; body) were also scored for microscopic fibrillation and tears (0–3) and inner border degeneration (0–3).
Results: Partial meniscal tears were present on both femoral and tibial surfaces in all 3 regions and most frequently identified on the femoral surface of the cranial horn of the medial meniscus and body of the lateral meniscus. There was a significantly positive correlation between the global medial meniscal macroscopic scores and osteophyte (r = 0.7, P = 0.002) or cartilage degeneration (r = 0.5, P = 0.03) scores within the medial femorotibial joint. The global medial meniscal macroscopic score was greater (P = 0.004) in the advanced OA joints compared with control joints.
Main limitations: The menisci were principally from abattoir specimens without a known clinical history because of the challenge in obtaining a large number of specimens with a clinical diagnosis of femorotibial OA.
Conclusions: This study is the first to describe normal equine meniscal morphology and lesions. Meniscal lesions were identified in all segments and on both articular surfaces. Meniscal degeneration significantly correlated with OA severity in the equine medial femorotibial joint. The relationship between OA and meniscal pathology remains to be elucidated
Structure of shells in complex networks
In a network, we define shell as the set of nodes at distance
with respect to a given node and define as the fraction of nodes
outside shell . In a transport process, information or disease usually
diffuses from a random node and reach nodes shell after shell. Thus,
understanding the shell structure is crucial for the study of the transport
property of networks. For a randomly connected network with given degree
distribution, we derive analytically the degree distribution and average degree
of the nodes residing outside shell as a function of . Further,
we find that follows an iterative functional form
, where is expressed in terms of the generating
function of the original degree distribution of the network. Our results can
explain the power-law distribution of the number of nodes found in
shells with larger than the network diameter , which is the average
distance between all pairs of nodes. For real world networks the theoretical
prediction of deviates from the empirical . We introduce a
network correlation function to
characterize the correlations in the network, where is the
empirical value and is the theoretical prediction.
indicates perfect agreement between empirical results and theory. We apply
to several model and real world networks. We find that the networks
fall into two distinct classes: (i) a class of {\it poorly-connected} networks
with , which have larger average distances compared with randomly
connected networks with the same degree distributions; and (ii) a class of {\it
well-connected} networks with
Sensory Activation of Command Cells for Locomotion and Modulatory Mechanisms: Lessons from Lampreys
Sensorimotor transformation is one of the most fundamental and ubiquitous functions of the central nervous system. Although the general organization of the locomotor neural circuitry is relatively well understood, less is known about its activation by sensory inputs and its modulation. Utilizing the lamprey model, a detailed understanding of sensorimotor integration in vertebrates is emerging. In this article, we explore how the vertebrate central nervous system integrates sensory signals to generate motor behavior by examining the pathways and neural mechanisms involved in the transformation of cutaneous and olfactory inputs into motor output in the lamprey. We then review how 5-HT acts on these systems by modulating both sensory inputs and motor output. A comprehensive review of this fundamental topic should provide a useful framework in the fields of motor control, sensorimotor integration and neuromodulation
Bounded and unitary elements in pro-C^*-algebras
A pro-C^*-algebra is a (projective) limit of C^*-algebras in the category of
topological *-algebras. From the perspective of non-commutative geometry,
pro-C^*-algebras can be seen as non-commutative k-spaces. An element of a
pro-C^*-algebra is bounded if there is a uniform bound for the norm of its
images under any continuous *-homomorphism into a C^*-algebra. The *-subalgebra
consisting of the bounded elements turns out to be a C^*-algebra. In this
paper, we investigate pro-C^*-algebras from a categorical point of view. We
study the functor (-)_b that assigns to a pro-C^*-algebra the C^*-algebra of
its bounded elements, which is the dual of the Stone-\v{C}ech-compactification.
We show that (-)_b is a coreflector, and it preserves exact sequences. A
generalization of the Gelfand-duality for commutative unital pro-C^*-algebras
is also presented.Comment: v2 (accepted
Systematic review of diagnostic tests for reproductive-tract infection and inflammation in dairy cows
The objective of this study was to conduct a systematic and critical appraisal
of the quality of previous publications and describe diagnostic methods,
diagnostic criteria and definitions, repeatability, and agreement among
methods for diagnosis of vaginitis, cervicitis, endometritis, salpingitis, and
oophoritis in dairy cows. Publications (n = 1,600) that included the words
"dairy," "cows," and at least one disease of interest were located with online
search engines. In total, 51 papers were selected for comprehensive review by
pairs of the authors. Only 61% (n = 31) of the 51 reviewed papers provided a
definition or citation for the disease or diagnostic methods studied, and only
49% (n = 25) of the papers provided the data or a citation to support the test
cut point used for diagnosing disease. Furthermore, a large proportion of the
papers did not provide sufficient detail to allow critical assessment of the
quality of design or reporting. Of 11 described diagnostic methods, only one
complete methodology, i.e., vaginoscopy, was assessed for both within- and
between-operator repeatability (κ = 0.55-0.60 and 0.44, respectively). In the
absence of a gold standard, comparisons between different tests have been
undertaken. Agreement between the various diagnostic methods is at a low
level. These discrepancies may indicate that these diagnostic methods assess
different aspects of reproductive health and underline the importance of tying
diagnostic criteria to objective measures of reproductive performance. Those
studies that used a reproductive outcome to select cut points and tests have
the greatest clinical utility. This approach has demonstrated, for example,
that presence of (muco)purulent discharge in the vagina and an increased
proportion of leukocytes in cytological preparations following uterine lavage
or cytobrush sampling are associated with poorer reproductive outcomes. The
lack of validated, consistent definitions and outcome variables makes
comparisons of the different tests difficult. The quality of design and
reporting in future publications could be improved by using checklists as a
guideline. Further high-quality research based on published standards to
improve study design and reporting should improve cow-side diagnostic tests.
Specifically, more data on intra- and interobserver agreement are needed to
evaluate test variability. Also, more studies are necessary to determine
optimal cut points and time postpartum of examination
Dynamical chaos and power spectra in toy models of heteropolymers and proteins
The dynamical chaos in Lennard-Jones toy models of heteropolymers is studied
by molecular dynamics simulations. It is shown that two nearby trajectories
quickly diverge from each other if the heteropolymer corresponds to a random
sequence. For good folders, on the other hand, two nearby trajectories may
initially move apart but eventually they come together. Thus good folders are
intrinsically non-chaotic. A choice of a distance of the initial conformation
from the native state affects the way in which a separation between the twin
trajectories behaves in time. This observation allows one to determine the size
of a folding funnel in good folders. We study the energy landscapes of the toy
models by determining the power spectra and fractal characteristics of the
dependence of the potential energy on time. For good folders, folding and
unfolding trajectories have distinctly different correlated behaviors at low
frequencies.Comment: 8 pages, 9 EPS figures, Phys. Rev. E (in press
Slowly synchronizing automata and digraphs
We present several infinite series of synchronizing automata for which the
minimum length of reset words is close to the square of the number of states.
These automata are closely related to primitive digraphs with large exponent.Comment: 13 pages, 5 figure
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