218 research outputs found
Letter from John Waddell, et al. to George Sibley, July 17, 1834
Transcript of Letter from John Waddell, et al. to George Sibley, July 17, 1834. Waddell and others discuss hard and liberal Whigs; Missouri politics
Polynomial diffeomorphisms of C^2, IV: The measure of maximal entropy and laminar currents
This paper concerns the dynamics of polynomial automorphisms of .
One can associate to such an automorphism two currents and the
equilibrium measure . In this paper we study some
geometric and dynamical properties of these objects. First, we characterize
as the unique measure of maximal entropy. Then we show that the measure
has a local product structure and that the currents have a
laminar structure. This allows us to deduce information about periodic points
and heteroclinic intersections. For example, we prove that the support of
coincides with the closure of the set of saddle points. The methods used
combine the pluripotential theory with the theory of non-uniformly hyperbolic
dynamical systems
Compaction of Hyaloclastite from the Active Geothermal System at Krafla Volcano, Iceland
Hyaloclastites commonly form high-quality reservoir rocks in volcanic geothermal provinces. Here, we investigated the effects of confinement due to burial following prolonged accumulation of eruptive products on the physical and mechanical evolution of surficial and subsurface (depths of 70 m, 556 m, and 732 m) hyaloclastites from Krafla volcano, Iceland. Upon loading in a hydrostatic cell, the porosity and permeability of the surficial hyaloclastite decreased linearly with mean effective stress, as pores and cracks closed due to elastic (recoverable) compaction up to 22-24 MPa (equivalent to ~1.3 km depth in the reservoir). Beyond this mean effective stress, denoted as P∗, we observed accelerated porosity and permeability reduction with increasing confinement, as the rock underwent permanent inelastic compaction. In comparison, the porosity and permeability of the subsurface core samples were less sensitive to mean effective stress, decreasing linearly with increasing confinement as the samples compacted elastically within the conditions tested (to 40 MPa). Although the surficial material underwent permanent, destructive compaction, it maintained higher porosity and permeability than the subsurface hyaloclastites throughout the experiments. We constrained the evolution of yield curves of the hyaloclastites, subjected to different effective mean stresses in a triaxial press. Surficial hyaloclastites underwent a brittle-ductile transition at an effective mean stress of ~10.5 MPa, and peak strength (differential stress) reached 13 MPa. When loaded to effective mean stresses of 33 and 40 MPa, the rocks compacted, producing new yield curves with a brittle-ductile transition at ~12.5 and ~19 MPa, respectively, but showed limited strength increase. In comparison, the subsurface samples were found to be much stronger, displaying higher strengths and brittle-ductile transitions at higher effective mean stresses (i.e., 37.5 MPa for 70 m sample, >75 MPa for 556 m, and 68.5 MPa for 732 m) that correspond to their lower porosities and permeabilities. Thus, we conclude that compaction upon burial alone is insufficient to explain the physical and mechanical properties of the subsurface hyaloclastites present in the reservoir at Krafla volcano. Mineralogical alteration, quantified using SEM-EDS, is invoked to explain the further reduction of porosity and increase in strength of the hyaloclastite in the active geothermal system at Krafla
Serum methylarginines and spirometry-measured lung function in older adults
Rationale: Methylarginines are endogenous nitric oxide synthase inhibitors that have been implicated in animal models of lung disease but have not previously been examined for their association with spirometric measures of lung function in humans.
Objectives: This study measured serum concentrations of asymmetric and symmetric dimethylarginine in a representative sample of older community-dwelling adults and determined their association with spirometric lung function measures.
Methods: Data on clinical, lifestyle, and demographic characteristics, methylated arginines, and L-arginine (measured using LC-MS/MS) were collected from a population-based sample of older Australian adults from the Hunter Community Study.
The five key lung function measures included as outcomes were Forced Expiratory Volume in 1 second, Forced Vital Capacity, Forced Expiratory Volume in 1 second to Forced Vital Capacity ratio, Percent Predicted Forced Expiratory Volume in 1 second, and Percent Predicted Forced Vital Capacity.
Measurements and Main Results: In adjusted analyses there were statistically significant independent associations between a) higher asymmetric dimethylarginine, lower Forced Expiratory Volume in 1 second and lower Forced Vital Capacity; and b) lower L-arginine/asymmetric dimethylarginine ratio, lower Forced Expiratory Volume in 1 second, lower Percent Predicted Forced Expiratory Volume in 1 second and lower Percent Predicted Forced Vital Capacity. By contrast, no significant associations were observed between symmetric dimethylarginine and lung function.
Conclusions: After adjusting for clinical, demographic, biochemical, and pharmacological confounders, higher serum asymmetric dimethylarginine was independently associated with a reduction in key measures of lung function. Further research is needed to determine if methylarginines predict the decline in lung function
Global circulation patterns of seasonal influenza viruses vary with antigenic drift.
Understanding the spatiotemporal patterns of emergence and circulation of new human seasonal influenza virus variants is a key scientific and public health challenge. The global circulation patterns of influenza A/H3N2 viruses are well characterized, but the patterns of A/H1N1 and B viruses have remained largely unexplored. Here we show that the global circulation patterns of A/H1N1 (up to 2009), B/Victoria, and B/Yamagata viruses differ substantially from those of A/H3N2 viruses, on the basis of analyses of 9,604 haemagglutinin sequences of human seasonal influenza viruses from 2000 to 2012. Whereas genetic variants of A/H3N2 viruses did not persist locally between epidemics and were reseeded from East and Southeast Asia, genetic variants of A/H1N1 and B viruses persisted across several seasons and exhibited complex global dynamics with East and Southeast Asia playing a limited role in disseminating new variants. The less frequent global movement of influenza A/H1N1 and B viruses coincided with slower rates of antigenic evolution, lower ages of infection, and smaller, less frequent epidemics compared to A/H3N2 viruses. Detailed epidemic models support differences in age of infection, combined with the less frequent travel of children, as probable drivers of the differences in the patterns of global circulation, suggesting a complex interaction between virus evolution, epidemiology, and human behaviour.T.B.
was
supported
by
a
Newton
International
Fellowship
from
the
Royal
Society
and
through
NIH
U54
GM111274.
S.R.
was
supported
by
MRC
(UK,
Project
MR/J008761/1),
Wellcome
Trust
(UK,
Project
093488/Z/10/Z),
Fogarty
International
Centre
(USA,
R01
TW008246‐01),
DHS
(USA,
RAPIDD
program),
NIGMS
(USA,
MIDAS
U01
GM110721‐01)
and
NIHR
(UK,
Health
Protection
Research
Unit
funding).
The
Melbourne
WHO
Collaborating
Centre
for
Reference
and
Research
on
Influenza
was
supported
by
the
Australian
Government
Department
of
Health
and
thanks
N.
Komadina
and
Y.‐M.
Deng.
The
Atlanta
WHO
Collaborating
Center
for
Surveillance,
Epidemiology
and
Control
of
Influenza
was
supported
by
the
U.S.
Department
of
13
Health
and
Human
Services.
NIV
thanks
A.C.
Mishra,
M.
Chawla‐Sarkar,
A.M.
Abraham,
D.
Biswas,
S.
Shrikhande,
AnuKumar
B,
and
A.
Jain.
Influenza
surveillance
in
India
was
expanded,
in
part,
through
US
Cooperative
Agreements
(5U50C1024407
and
U51IP000333)
and
by
the
Indian
Council
of
Medical
Research.
M.A.S.
was
supported
through
NSF
DMS
1264153
and
NIH
R01
AI
107034.
Work
of
the
WHO
Collaborating
Centre
for
Reference
and
Research
on
Influenza
at
the
MRC
National
Institute
for
Medical
Research
was
supported
by
U117512723.
P.L.,
A.R.
&
M.A.S
were
supported
by
EU
Seventh
Framework
Programme
[FP7/2007‐2013]
under
Grant
Agreement
no.
278433-‐PREDEMICS
and
ERC
Grant
agreement
no.
260864.
C.A.R.
was
supported
by
a
University
Research
Fellowship
from
the
Royal
Society.This is the author accepted manuscript. It is currently under infinite embargo pending publication of the final version
Classification of recurrent domains for some holomorphic maps
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46244/1/208_2005_Article_BF01446660.pd
Crafting Critical Heritage Discourses into Interactive Exhibition Design
This paper argues how a more reflective design practice that embraces critical discourses can transform interactive exhibition design and therefore the museum visiting experience. Four framing arguments underpin our exhibition design making: the value of materiality, visiting as an aesthetic experience, challenging the authorized voice, and heritage as a process. These arguments were embodied through design, art and craft practice into one interactive exhibition at a house museum. We draw from our design process discussing the implications that adopting an approach informed by critical heritage debates has on exhibition design and suggest three sensitizing concepts (polyvocal narratives, dialogical interaction, interweaving time and space) bridging the practice of interactive exhibition design and critical heritage theory
Genome-wide evolutionary dynamics of influenza B viruses on a global scale
The global-scale epidemiology and genome-wide evolutionary dynamics of influenza B remain poorly understood compared with influenza A viruses. We compiled a spatio-temporally comprehensive dataset of influenza B viruses, comprising over 2,500 genomes sampled worldwide between 1987 and 2015, including 382 newly-sequenced genomes that fill substantial gaps in previous molecular surveillance studies. Our contributed data increase the number of available influenza B virus genomes in Europe, Africa and Central Asia, improving the global context to study influenza B viruses. We reveal Yamagata-lineage diversity results from co-circulation of two antigenically-distinct groups that also segregate genetically across the entire genome, without evidence of intra-lineage reassortment. In contrast, Victoria-lineage diversity stems from geographic segregation of different genetic clades, with variability in the degree of geographic spread among clades. Differences between the lineages are reflected in their antigenic dynamics, as Yamagata-lineage viruses show alternating dominance between antigenic groups, while Victoria-lineage viruses show antigenic drift of a single lineage. Structural mapping of amino acid substitutions on trunk branches of influenza B gene phylogenies further supports these antigenic differences and highlights two potential mechanisms of adaptation for polymerase activity. Our study provides new insights into the epidemiological and molecular processes shaping influenza B virus evolution globally
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