417 research outputs found
The genome and transcriptome of Trichormus sp NMC-1: insights into adaptation to extreme environments on the Qinghai-Tibet Plateau
The Qinghai-Tibet Plateau (QTP) has the highest biodiversity for an extreme environment worldwide, and provides an ideal natural laboratory to study adaptive evolution. In this study, we generated a draft genome sequence of cyanobacteria Trichormus sp. NMC-1 in the QTP and performed whole transcriptome sequencing under low temperature to investigate the genetic mechanism by which T. sp. NMC-1 adapted to the specific environment. Its genome sequence was 5.9 Mb with a G+C content of 39.2% and encompassed a total of 5362 CDS. A phylogenomic tree indicated that this strain belongs to the Trichormus and Anabaena cluster. Genome comparison between T. sp. NMC-1 and six relatives showed that functionally unknown genes occupied a much higher proportion (28.12%) of the T. sp. NMC-1 genome. In addition, functions of specific, significant positively selected, expanded orthogroups, and differentially expressed genes involved in signal transduction, cell wall/membrane biogenesis, secondary metabolite biosynthesis, and energy production and conversion were analyzed to elucidate specific adaptation traits. Further analyses showed that the CheY-like genes, extracellular polysaccharide and mycosporine-like amino acids might play major roles in adaptation to harsh environments. Our findings indicate that sophisticated genetic mechanisms are involved in cyanobacterial adaptation to the extreme environment of the QTP
Experimental observation of nonlinear Thomson scattering
A century ago, J. J. Thomson showed that the scattering of low-intensity
light by electrons was a linear process (i.e., the scattered light frequency
was identical to that of the incident light) and that light's magnetic field
played no role. Today, with the recent invention of ultra-high-peak-power
lasers it is now possible to create a sufficient photon density to study
Thomson scattering in the relativistic regime. With increasing light intensity,
electrons quiver during the scattering process with increasing velocity,
approaching the speed of light when the laser intensity approaches 10^18
W/cm^2. In this limit, the effect of light's magnetic field on electron motion
should become comparable to that of its electric field, and the electron mass
should increase because of the relativistic correction. Consequently, electrons
in such high fields are predicted to quiver nonlinearly, moving in figure-eight
patterns, rather than in straight lines, and thus to radiate photons at
harmonics of the frequency of the incident laser light, with each harmonic
having its own unique angular distribution. In this letter, we report the first
ever direct experimental confirmation of these predictions, a topic that has
previously been referred to as nonlinear Thomson scattering. Extension of these
results to coherent relativistic harmonic generation may eventually lead to
novel table-top x-ray sources.Comment: including 4 figure
Mutual information rate and bounds for it
The amount of information exchanged per unit of time between two nodes in a
dynamical network or between two data sets is a powerful concept for analysing
complex systems. This quantity, known as the mutual information rate (MIR), is
calculated from the mutual information, which is rigorously defined only for
random systems. Moreover, the definition of mutual information is based on
probabilities of significant events. This work offers a simple alternative way
to calculate the MIR in dynamical (deterministic) networks or between two data
sets (not fully deterministic), and to calculate its upper and lower bounds
without having to calculate probabilities, but rather in terms of well known
and well defined quantities in dynamical systems. As possible applications of
our bounds, we study the relationship between synchronisation and the exchange
of information in a system of two coupled maps and in experimental networks of
coupled oscillators
Epidemiology of Coxiella burnetii infection in Africa: a OneHealth systematic review
Background:
Q fever is a common cause of febrile illness and community-acquired pneumonia in resource-limited settings. Coxiella burnetii, the causative pathogen, is transmitted among varied host species, but the epidemiology of the organism in Africa is poorly understood. We conducted a systematic review of C. burnetii epidemiology in Africa from a “One Health” perspective to synthesize the published data and identify knowledge gaps.<p></p>
Methods/Principal Findings:
We searched nine databases to identify articles relevant to four key aspects of C. burnetii epidemiology in human and animal populations in Africa: infection prevalence; disease incidence; transmission risk factors; and infection control efforts. We identified 929 unique articles, 100 of which remained after full-text review. Of these, 41 articles describing 51 studies qualified for data extraction. Animal seroprevalence studies revealed infection by C. burnetii (≤13%) among cattle except for studies in Western and Middle Africa (18–55%). Small ruminant seroprevalence ranged from 11–33%. Human seroprevalence was <8% with the exception of studies among children and in Egypt (10–32%). Close contact with camels and rural residence were associated with increased seropositivity among humans. C. burnetii infection has been associated with livestock abortion. In human cohort studies, Q fever accounted for 2–9% of febrile illness hospitalizations and 1–3% of infective endocarditis cases. We found no studies of disease incidence estimates or disease control efforts.<p></p>
Conclusions/Significance:
C. burnetii infection is detected in humans and in a wide range of animal species across Africa, but seroprevalence varies widely by species and location. Risk factors underlying this variability are poorly understood as is the role of C. burnetii in livestock abortion. Q fever consistently accounts for a notable proportion of undifferentiated human febrile illness and infective endocarditis in cohort studies, but incidence estimates are lacking. C. burnetii presents a real yet underappreciated threat to human and animal health throughout Africa.<p></p>
The smectic order of wrinkles
A thin elastic sheet lying on a soft substrate develops wrinkled patterns when subject to an external forcing or as a result of geometric incompatibility. Thin sheet elasticity and substrate response equip such wrinkles with a global preferred wrinkle spacing length and with resistance to wrinkle curvature. These features are responsible for the liquid crystalline smectic-like behaviour of such systems at intermediate length scales. This insight allows better understanding of the wrinkling patterns seen in such systems, with which we explain pattern breaking into domains, the properties of domain walls and wrinkle undulation. We compare our predictions with numerical simulations and with experimental observations
Observation of the Charmed Baryon at CLEO
The CLEO experiment at the CESR collider has used 13.7 fb of data to
search for the production of the (css-ground state) in
collisions at {\rm GeV}. The modes used to
study the are ,
, , , and
. We observe a signal of 40.49.0(stat) events
at a mass of 2694.62.6(stat)1.9(syst) {\rm MeV/}, for all modes
combined.Comment: 10 pages postscript, also available through
http://w4.lns.cornell.edu/public/CLN
Measurements of B --> D_s^{(*)+} D^{*(*)} Branching Fractions
This article describes improved measurements by CLEO of the and branching fractions, and first evidence
for the decay , where
represents the sum of the , , and
L=1 charm meson states. Also reported is the first
measurement of the polarization in the decay . A partial reconstruction technique, employing only the fully
reconstructed and slow pion from the decay, enhances sensitivity. The observed branching fractions are
, , and , where the first error is statistical,
the second systematic, and the third is due to the uncertainty in the branching fraction. The measured longitudinal
polarization, , is consistent with
the factorization prediction of 54%.Comment: 26 pages (LaTeX), 15 figures. To be submitted to PR
Mesenchymal stem cell-conditioned medium reduces disease severity and immune responses in inflammatory arthritis
We evaluated the therapeutic potential of mesenchymal stem cell-conditioned medium (CM-MSC) as an alternative to cell therapy in an antigen-induced model of arthritis (AIA). Disease severity and cartilage loss were evaluated by histopathological analysis of arthritic knee joints and immunostaining of aggrecan neoepitopes. Cell proliferation was assessed for activated and naïve CD4+ T cells from healthy mice following culture with CM-MSC or co-culture with MSCs. T cell polarization was analysed in CD4+ T cells isolated from spleens and lymph nodes of arthritic mice treated with CM-MSC or MSCs. CM-MSC treatment significantly reduced knee-joint swelling, histopathological signs of AIA, cartilage loss and suppressed TNFα induction. Proliferation of CD4+ cells from spleens of healthy mice was not affected by CM-MSC but reduced when cells were co-cultured with MSCs. In the presence of CM-MSC or MSCs, increases in IL-10 concentration were observed in culture medium. Finally, CD4+ T cells from arthritic mice treated with CM-MSC showed increases in FOXP3 and IL-4 expression and positively affected the Treg:Th17 balance in the tissue. CM-MSC treatment reduces cartilage damage and suppresses immune responses by reducing aggrecan cleavage, enhancing Treg function and adjusting the Treg:Th17 ratio. CM-MSC may provide an effective cell-free therapy for inflammatory arthritis
The Evolutionary Basis of Naturally Diverse Rice Leaves Anatomy
Rice contains genetically and ecologically diverse wild and cultivated species that show a
wide variation in plant and leaf architecture. A systematic characterization of leaf anatomy
is essential in understanding the dynamics behind such diversity. Therefore, leaf anatomies
of 24 Oryza species spanning 11 genetically diverse rice genomes were studied in both lateral
and longitudinal directions and possible evolutionary trends were examined. A significant
inter-species variation in mesophyll cells, bundle sheath cells, and vein structure was
observed, suggesting precise genetic control over these major rice leaf anatomical traits.
Cellular dimensions, measured along three growth axes, were further combined proportionately
to construct three-dimensional (3D) leaf anatomy models to compare the relative size
and orientation of the major cell types present in a fully expanded leaf. A reconstruction of
the ancestral leaf state revealed that the following are the major characteristics of recently
evolved rice species: fewer veins, larger and laterally elongated mesophyll cells, with an
increase in total mesophyll area and in bundle sheath cell number. A huge diversity in leaf
anatomy within wild and domesticated rice species has been portrayed in this study, on an
evolutionary context, predicting a two-pronged evolutionary pathway leading to the ‘sativa
leaf type’ that we see today in domesticated species
Sharing vocabularies: towards horizontal alignment of values-driven business functions
This paper highlights the emergence of different ‘vocabularies’ that describe various values-driven business functions within large organisations and argues for improved horizontal alignment between them. We investigate two established functions that have long-standing organisational histories: Ethics and Compliance (E&C) and Corporate Social Responsibility (CSR). By drawing upon research on organisational alignment, we explain both the need for and the potential benefit of greater alignment between these values-driven functions. We then examine the structural and socio-cultural dimensions of organisational systems through which E&C and CSR horizontal alignment can be coordinated to improve synergies, address tensions, and generate insight to inform future research and practice in the field of Business and Society. The paper concludes with research questions that can inform future scholarly research and a practical model to guide organizations’ efforts towards inter-functional, horizontal alignment of values-driven organizational practice
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