829 research outputs found
Emerging Infectious Disease leads to Rapid Population Decline of Common British Birds
Emerging infectious diseases are increasingly cited as threats to wildlife, livestock and humans alike. They can threaten geographically isolated or critically endangered wildlife populations; however, relatively few studies have clearly demonstrated the extent to which emerging diseases can impact populations of common wildlife species. Here, we report the impact of an emerging protozoal disease on British populations of greenfinch Carduelis chloris and chaffinch Fringilla coelebs, two of the most common birds in Britain. Morphological and molecular analyses showed this to be due to Trichomonas gallinae. Trichomonosis emerged as a novel fatal disease of finches in Britain in 2005 and rapidly became epidemic within greenfinch, and to a lesser extent chaffinch, populations in 2006. By 2007, breeding populations of greenfinches and chaffinches in the geographic region of highest disease incidence had decreased by 35% and 21% respectively, representing mortality in excess of half a million birds. In contrast, declines were less pronounced or absent in these species in regions where the disease was found in intermediate or low incidence. Also, populations of dunnock Prunella modularis, which similarly feeds in gardens, but in which T. gallinae was rarely recorded, did not decline. This is the first trichomonosis epidemic reported in the scientific literature to negatively impact populations of free-ranging non-columbiform species, and such levels of mortality and decline due to an emerging infectious disease are unprecedented in British wild bird populations. This disease emergence event demonstrates the potential for a protozoan parasite to jump avian host taxonomic groups with dramatic effect over a short time period
Analysis of Protein Palmitoylation Reveals a Pervasive Role in Plasmodium Development and Pathogenesis
Asexual stage Plasmodium falciparum replicates
and undergoes a tightly regulated developmental
process in human erythrocytes. One mechanism
involved in the regulation of this process is posttranslational
modification (PTM) of parasite proteins.
Palmitoylation is a PTM in which cysteine residues
undergo a reversible lipid modification, which can
regulate target proteins in diverse ways. Using complementary
palmitoyl protein purification approaches
and quantitative mass spectrometry, we
examined protein palmitoylation in asexual-stage
P. falciparum parasites and identified over 400 palmitoylated
proteins, including those involved in cytoadherence,
drug resistance, signaling, development,
and invasion. Consistent with the prevalence of
palmitoylated proteins, palmitoylation is essential
for P. falciparum asexual development and influences
erythrocyte invasion by directly regulating
the stability of components of the actin-myosin invasion
motor. Furthermore, P. falciparum uses palmitoylation
in diverse ways, stably modifying some
proteins while dynamically palmitoylating others.
Palmitoylation therefore plays a central role in regulating
P. falciparum blood stage development
Coordinated Monitoring of the Eccentric O-star Binary Iota Orionis: The X-ray Analysis
We analyse two ASCA observations of the highly eccentric O9III + B1III binary
Iota Orionis obtained at periastron and apastron. Based on the assumption of a
strong colliding winds shock between the stellar components, we expected to see
significant variation in the X-ray emission between these phases. The
observations proved otherwise: the X-ray luminosities and spectral
distributions were remarkably similar. The only noteworthy feature was the hint
of a proximity effect during periastron passage, supported also in the optical.
We discuss the accuracy of our results, and also analyse archival ROSAT
observations. We investigate why we do not see a clear colliding winds
signature. A simple model shows that the wind attenuation to the expected
position of the shock apex is negligible throughout the orbit, which poses the
puzzling question of why the expected 1/D variation (ie. a factor of 7.5) in
the intrinsic luminosity is not seen in the data. Two scenarios are proposed:
either the colliding winds emission is unexpectedly weak such that intrinsic
shocks in the winds dominate the emission, or, alternatively, that the emission
observed is colliding winds emission but in a more complex form than we would
naively expect. Complex hydrodynamical models are then analyzed. Despite
strongly phase-variable emission from the models, both were consistent with the
observations. We find that if the mass-loss rates of the stars are low then
intrinsic wind shocks could dominate the emission. However, when we assume
higher mass-loss rates of the stars, we find that the observed emission could
also be consistent with a purely colliding winds origin. To distinguish between
the different models X-ray observations with improved phase coverage will be
necessary.Comment: 18 pages, 14 figures, uses mn.st
Measurement of the cosmic ray spectrum above eV using inclined events detected with the Pierre Auger Observatory
A measurement of the cosmic-ray spectrum for energies exceeding
eV is presented, which is based on the analysis of showers
with zenith angles greater than detected with the Pierre Auger
Observatory between 1 January 2004 and 31 December 2013. The measured spectrum
confirms a flux suppression at the highest energies. Above
eV, the "ankle", the flux can be described by a power law with
index followed by
a smooth suppression region. For the energy () at which the
spectral flux has fallen to one-half of its extrapolated value in the absence
of suppression, we find
eV.Comment: Replaced with published version. Added journal reference and DO
Energy Estimation of Cosmic Rays with the Engineering Radio Array of the Pierre Auger Observatory
The Auger Engineering Radio Array (AERA) is part of the Pierre Auger
Observatory and is used to detect the radio emission of cosmic-ray air showers.
These observations are compared to the data of the surface detector stations of
the Observatory, which provide well-calibrated information on the cosmic-ray
energies and arrival directions. The response of the radio stations in the 30
to 80 MHz regime has been thoroughly calibrated to enable the reconstruction of
the incoming electric field. For the latter, the energy deposit per area is
determined from the radio pulses at each observer position and is interpolated
using a two-dimensional function that takes into account signal asymmetries due
to interference between the geomagnetic and charge-excess emission components.
The spatial integral over the signal distribution gives a direct measurement of
the energy transferred from the primary cosmic ray into radio emission in the
AERA frequency range. We measure 15.8 MeV of radiation energy for a 1 EeV air
shower arriving perpendicularly to the geomagnetic field. This radiation energy
-- corrected for geometrical effects -- is used as a cosmic-ray energy
estimator. Performing an absolute energy calibration against the
surface-detector information, we observe that this radio-energy estimator
scales quadratically with the cosmic-ray energy as expected for coherent
emission. We find an energy resolution of the radio reconstruction of 22% for
the data set and 17% for a high-quality subset containing only events with at
least five radio stations with signal.Comment: Replaced with published version. Added journal reference and DO
Measurement of the Radiation Energy in the Radio Signal of Extensive Air Showers as a Universal Estimator of Cosmic-Ray Energy
We measure the energy emitted by extensive air showers in the form of radio
emission in the frequency range from 30 to 80 MHz. Exploiting the accurate
energy scale of the Pierre Auger Observatory, we obtain a radiation energy of
15.8 \pm 0.7 (stat) \pm 6.7 (sys) MeV for cosmic rays with an energy of 1 EeV
arriving perpendicularly to a geomagnetic field of 0.24 G, scaling
quadratically with the cosmic-ray energy. A comparison with predictions from
state-of-the-art first-principle calculations shows agreement with our
measurement. The radiation energy provides direct access to the calorimetric
energy in the electromagnetic cascade of extensive air showers. Comparison with
our result thus allows the direct calibration of any cosmic-ray radio detector
against the well-established energy scale of the Pierre Auger Observatory.Comment: Replaced with published version. Added journal reference and DOI.
Supplemental material in the ancillary file
Therapeutic and prophylactic effect of intermittent preventive anti-malarial treatment in infants (IPTi) from Ghana and Gabon
<p>Abstract</p> <p>Background</p> <p>Intermittent preventive treatment in infants (IPTi) with sulphadoxine-pyrimethamine (SP) reduces the incidence of malaria episodes in young children. The exact mechanism by which the protective effect is mediated needs to be defined. This study aimed to investigate therapeutic, prophylactic, and possible exceeding effects of SP-based IPTi in two clinical trials.</p> <p>Methods</p> <p>Protective efficacies from two IPTi trials performed in Kumasi, Ghana, and Lambaréné, Gabon, were assessed for overlapping time series of 61 days. For six-months periods after each of three IPTi doses a multivariate Poisson regression model with the respective cohort as co-variate was generated and effect modification of protective efficacy with time strata was evaluated by log-likelihood tests.</p> <p>Results</p> <p>Protective efficacies were not significantly different between the two study cohorts. Study-cohort corrected protective efficacy was highest for the first 61 days after each IPTi application and decreased continuously. For the first 61 days after IPTi-1, IPTi-2, and IPTi-3 the protective efficacy was 71%, 44%, and 43%, respectively. A reduction of the malaria incidence rate was detectable for the first 60, 30 and 40 days after IPTi-1, IPTi-2 and IPTi-3 drug application, respectively. After IPTi-3 a higher risk for malaria could be seen after day 60. This effect was mainly based on the overwhelming influence of the Kumasi cohort.</p> <p>Conclusion</p> <p>The results suggest that SP-based IPTi mainly works through a therapeutic and prophylactic effect over 30 to 60 days after drug application and that a sustained effect beyond post-treatment prophylaxis might be very low.</p> <p>Trial registration</p> <p>Data analysis from clinical trials NCT ID # 00206739 (Kumasi Trial) and NCT ID # 00167843 (Lambaréné Trial), <url>http://www.clinicaltrials.gov</url>.</p
Red Aesthetics, Intermediality and the Use of Posters in Chinese Cinema after 1949
Abstract: This article focuses on the aesthetic and affective techniques of saturation through which posters legitimated the Party-State in Mao’s China by closing the gap between everyday experience and political ideology. Propaganda posters were designed to put into practice the principle of unity, as conceptua- lised by Mao Zedong. The argument posits that while the “poster” is normally a printed edition of a painting or design intended for mass distribution in this way, the term may fairly be deployed to capture other cultural objects that function as “posters”, in that they provide public, political information that expresses or con- structs a political self in aesthetic form. This approach requires a metonymic understanding of a visual field in which cultural objects are interrelated and mutually reinforcing. The essay draws on recent in-depth interviews with poster artists of the 1960s and 1970s
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