613 research outputs found
Constraining High Speed Winds in Exoplanet Atmospheres Through Observations of Anomalous Doppler Shifts During Transit
Three-dimensional (3-D) dynamical models of hot Jupiter atmospheres predict
very strong wind speeds. For tidally locked hot Jupiters, winds at high
altitude in the planet's atmosphere advect heat from the day side to the cooler
night side of the planet. Net wind speeds on the order of 1-10 km/s directed
towards the night side of the planet are predicted at mbar pressures, which is
the approximate pressure level probed by transmission spectroscopy. These winds
should result in an observed blue shift of spectral lines in transmission on
the order of the wind speed. Indeed, Snellen et al. (2010) recently observed a
2 +/- 1 km/s blue shift of CO transmission features for HD 209458b, which has
been interpreted as a detection of the day-to-night winds that have been
predicted by 3-D atmospheric dynamics modeling. Here we present the results of
a coupled 3-D atmospheric dynamics and transmission spectrum model, which
predicts the Doppler-shifted spectrum of a hot Jupiter during transit resulting
from winds in the planet's atmosphere. We explore four different models for the
hot Jupiter atmosphere using different prescriptions for atmospheric drag via
interaction with planetary magnetic fields. We find that models with no
magnetic drag produce net Doppler blue shifts in the transmission spectrum of
~2 km/s and that lower Doppler shifts of ~1 km/s are found for the higher drag
cases, results consistent with -- but not yet strongly constrained by -- the
Snellen et al. (2010) measurement. We additionally explore the possibility of
recovering the average terminator wind speed as a function of altitude by
measuring Doppler shifts of individual spectral lines and spatially resolving
wind speeds across the leading and trailing terminators during ingress and
egress.Comment: Submitted to ApJ, 28 pages including 9 figures in manuscript forma
A General Circulation Model for Gaseous Exoplanets with Double-Gray Radiative Transfer
We present a new version of our code for modeling the atmospheric circulation
on gaseous exoplanets, now employing a "double-gray" radiative transfer scheme,
which self-consistently solves for fluxes and heating throughout the
atmosphere, including the emerging (observable) infrared flux. We separate the
radiation into infrared and optical components, each with its own absorption
coefficient, and solve standard two-stream radiative transfer equations. We use
a constant optical absorption coefficient, while the infrared coefficient can
scale as a powerlaw with pressure. Here we describe our new code in detail and
demonstrate its utility by presenting a generic hot Jupiter model. We discuss
issues related to modeling the deepest pressures of the atmosphere and describe
our use of the diffusion approximation for radiative fluxes at high optical
depths. In addition, we present new models using a simple form for magnetic
drag on the atmosphere. We calculate emitted thermal phase curves and find that
our drag-free model has the brightest region of the atmosphere offset by ~12
degrees from the substellar point and a minimum flux that is 17% of the
maximum, while the model with the strongest magnetic drag has an offset of only
~2 degrees and a ratio of 13%. Finally, we calculate rates of numerical loss of
kinetic energy at ~15% for every model except for our strong-drag model, where
there is no measurable loss; we speculate that this is due to the much
decreased wind speeds in that model.Comment: 29 pages, 12 figures, 2 tables, submitted to Ap
Three-Dimensional Atmospheric Circulation Models of HD 189733b and HD 209458b with Consistent Magnetic Drag and Ohmic Dissipation
We present the first three-dimensional circulation models for extrasolar gas
giant atmospheres with geometrically and energetically consistent treatments of
magnetic drag and ohmic dissipation. Atmospheric resistivities are continuously
updated and calculated directly from the flow structure, strongly coupling the
magnetic effects with the circulation pattern. We model the hot Jupiters HD
189733b (Teq \approx 1200 K) and HD 209458b (Teq \approx 1500 K) and test
planetary magnetic field strengths from 0 to 30 G. We find that even at B = 3 G
the atmospheric structure and circulation of HD 209458b are strongly influenced
by magnetic effects, while the cooler HD 189733b remains largely unaffected,
even in the case of B = 30 G and super-solar metallicities. Our models of HD
209458b indicate that magnetic effects can substantially slow down atmospheric
winds, change circulation and temperature patterns, and alter observable
properties. These models establish that longitudinal and latitudinal hot spot
offsets, day-night flux contrasts, and planetary radius inflation are
interrelated diagnostics of the magnetic induction process occurring in the
atmospheres of hot Jupiters and other similarly forced exoplanets. Most of the
ohmic heating occurs high in the atmosphere and on the day side of the planet,
while the heating at depth is strongly dependent on the internal heat flux
assumed for the planet, with more heating when the deep atmosphere is hot. We
compare the ohmic power at depth in our models, and estimates of the ohmic
dissipation in the bulk interior (from general scaling laws), to evolutionary
models that constrain the amount of heating necessary to explain the inflated
radius of HD 209458b. Our results suggest that deep ohmic heating can
successfully inflate the radius of HD 209458b for planetary magnetic field
strengths of B \geq 3 - 10 G.Comment: 35 pages, 12 figures, minimal revisions due to referee's comments,
ApJ accepte
Functional, motor, and sensory assessment instruments upon nerve repair in adult hands: Systematic review of psychometric properties
© 2018 The Author(s). Background: Outcome after nerve repair of the hand needs standardized psychometrically robust measures. We aimed to systematically review the psychometric properties of available functional, motor, and sensory assessment instruments after nerve repair. Methods: This systematic review of health measurement instruments searched databases from 1966 to 2017. Pairs of raters conducted data extraction and quality assessment using a structured tool for clinical measurement studies. Kappa correlation was used to define the agreement prior to consensus for individual items, and intraclass correlation coefficient (ICC) was used to assess reliability between raters. A narrative synthesis described quality and content of the evidence. Results: Sixteen studies were included for final critical appraisal scores. Kappa ranged from 0.31 to 0.82 and ICC was 0.81. Motor domain had manual muscle testing with Kappa from 0.72 to 0.93 and a dynamometer ICC reliability between 0.92 and 0.98. Sensory domain had touch threshold Semmes-Weinstein monofilaments (SWM) as the most responsive measure while two-point discrimination (2PD) was the least responsive (effect size 1.2 and 0.1). A stereognosis test, Shape and Texture Identification (STI), had Kappa test-retest reliability of 0.79 and inter-rater reliability of 0.61, with excellent sensibility and specificity. Manual tactile test had moderate to mild correlation with 2PD and SWM. Function domain presented Rosén-Lundborg score with Spearman correlations of 0.83 for total score. Patient-reported outcomes measurements had ICC of 0.85 and internal consistency from 0.88 to 0.96 with Patient-Rated Wrist and Hand Evaluation with higher score for reliability and Spearman correlation between 0.38 and 0.89 for validity. Conclusions: Few studies included nerve repair in their sample for the psychometric analysis of outcome measures, so moderate evidence could be confirmed. Manual muscle test and Rotterdam Intrinsic Hand Myometer dynamometer had excellent reliability but insufficient data on validity or responsiveness. Touch threshold testing was more responsive than 2PD test. The locognosia test and STI had limited but positive supporting data related to validity. Rosén-Lundborg score had emerging evidence of reliability and validity as a comprehensive outcome following nerve repair. Few questionnaires were considered reliable and valid to assess cold intolerance. There is no patient-reported outcome measurement following nerve repair that provides comprehensive assessment of symptoms and function by patient perspective
Neem oil or almond oil nanoemulsions for vitamin E Delivery: from structural evaluation to in vivo assessment of antioxidant and anti-inflammatory activity
Purpose: Vitamin E (VitE) may be classified in "the first line of defense" against the formation of reactive oxygen species. Its inclusion in nanoemulsions (NEs) is a promising alternative to increase its bioavailability. The aim of this study was to compare O/W NEs including VitE based on Almond or Neem oil, showing themselves antioxidant properties. The potential synergy of the antioxidant activities of oils and vitamin E, co-formulated in NEs, was explored.
Patients and methods: NEs have been prepared by sonication and deeply characterized evaluating size, ζ-potential, morphology (TEM and SAXS analyses), oil nanodroplet feature, and stability. Antioxidant activity has been evaluated in vitro, in non-tumorigenic HaCaT keratinocytes, and in vivo through fluorescence analysis of C. elegans transgenic strain. Moreover, on healthy human volunteers, skin tolerability and anti-inflammatory activity were evaluated by measuring the reduction of the skin erythema induced by the application of a skin chemical irritant (methyl-nicotinate).
Results: Results confirm that Vitamin E can be formulated in highly stable NEs showing good antioxidant activity on keratinocyte and on C. elegans. Interestingly, only Neem oil NEs showed some anti-inflammatory activity on healthy volunteers.
Conclusion: From the obtained results, Neem over Almond oil is a more appropriate candidate for further studies on this application
Plant Growth-Promoting Rhizobacteria: Context, Mechanisms of Action, and Roadmap to Commercialization of Biostimulants for Sustainable Agriculture
Microbes of the phytomicrobiome are associated with every plant tissue and, in combination with the plant form the holobiont. Plants regulate the composition and activity of their associated bacterial community carefully. These microbes provide a wide range of services and benefits to the plant; in return, the plant provides the microbial community with reduced carbon and other metabolites. Soils are generally a moist environment, rich in reduced carbon which supports extensive soil microbial communities. The rhizomicrobiome is of great importance to agriculture owing to the rich diversity of root exudates and plant cell debris that attract diverse and unique patterns of microbial colonization. Microbes of the rhizomicrobiome play key roles in nutrient acquisition and assimilation, improved soil texture, secreting, and modulating extracellular molecules such as hormones, secondary metabolites, antibiotics, and various signal compounds, all leading to enhancement of plant growth. The microbes and compounds they secrete constitute valuable biostimulants and play pivotal roles in modulating plant stress responses. Research has demonstrated that inoculating plants with plant-growth promoting rhizobacteria (PGPR) or treating plants with microbe-to-plant signal compounds can be an effective strategy to stimulate crop growth. Furthermore, these strategies can improve crop tolerance for the abiotic stresses (e.g., drought, heat, and salinity) likely to become more frequent as climate change conditions continue to develop. This discovery has resulted in multifunctional PGPR-based formulations for commercial agriculture, to minimize the use of synthetic fertilizers and agrochemicals. This review is an update about the role of PGPR in agriculture, from their collection to commercialization as low-cost commercial agricultural inputs. First, we introduce the concept and role of the phytomicrobiome and the agricultural context underlying food security in the 21st century. Next, mechanisms of plant growth promotion by PGPR are discussed, including signal exchange between plant roots and PGPR and how these relationships modulate plant abiotic stress responses via induced systemic resistance. On the application side, strategies are discussed to improve rhizosphere colonization by PGPR inoculants. The final sections of the paper describe the applications of PGPR in 21st century agriculture and the roadmap to commercialization of a PGPR-based technology
A Daphnane Diterpenoid Isolated from Wikstroemia polyantha Induces an Inflammatory Response and Modulates miRNA Activity
MicroRNAs (miRNAs) are endogenously expressed single-stranded ∼21–23 nucleotide RNAs that inhibit gene expression post-transcriptionally by binding imperfectly to elements usually within the 3′untranslated region (3′UTR) of mRNAs. Small interfering RNAs (siRNAs) mediate site-specific cleavage by binding with perfect complementarity to RNA. Here, a cell-based miRNA reporter system was developed to screen for compounds from marine and plant extracts that inhibit miRNA or siRNA activity. The daphnane diterpenoid genkwanine M (GENK) isolated from the plant Wikstroemia polyantha induces an early inflammatory response and can moderately inhibit miR-122 activity in the liver Huh-7 cell line. GENK does not alter miR-122 levels nor does it directly inhibit siRNA activity in an in vitro cleavage assay. Finally, we demonstrate that GENK can inhibit HCV infection in Huh-7 cells. In summary, the development of the cell-based miRNA sensor system should prove useful in identifying compounds that affect miRNA/siRNA activity
2018 Research & Innovation Day Program
A one day showcase of applied research, social innovation, scholarship projects and activities.https://first.fanshawec.ca/cri_cripublications/1005/thumbnail.jp
Crop pests and predators exhibit inconsistent responses to surrounding landscape composition
The idea that noncrop habitat enhances pest control and represents a win–win opportunity to conserve biodiversity and bolster yields has emerged as an agroecological paradigm. However, while noncrop habitat in landscapes surrounding farms sometimes benefits pest predators, natural enemy responses remain heterogeneous across studies and effects on pests are inconclusive. The observed heterogeneity in species responses to noncrop habitat may be biological in origin or could result from variation in how habitat and biocontrol are measured. Here, we use a pest-control database encompassing 132 studies and 6,759 sites worldwide to model natural enemy and pest abundances, predation rates, and crop damage as a function of landscape composition. Our results showed that although landscape composition explained significant variation within studies, pest and enemy abundances, predation rates, crop damage, and yields each exhibited different responses across studies, sometimes increasing and sometimes decreasing in landscapes with more noncrop habitat but overall showing no consistent trend. Thus, models that used landscape-composition variables to predict pest-control dynamics demonstrated little potential to explain variation across studies, though prediction did improve when comparing studies with similar crop and landscape features. Overall, our work shows that surrounding noncrop habitat does not consistently improve pest management, meaning habitat conservation may bolster production in some systems and depress yields in others. Future efforts to develop tools that inform farmers when habitat conservation truly represents a win–win would benefit from increased understanding of how landscape effects are modulated by local farm management and the biology of pests and their enemies
Towards a muon collider
A muon collider would enable the big jump ahead in energy reach that is needed for a fruitful exploration of fundamental interactions. The challenges of producing muon collisions at high luminosity and 10 TeV centre of mass energy are being investigated by the recently-formed International Muon Collider Collaboration. This Review summarises the status and the recent advances on muon colliders design, physics and detector studies. The aim is to provide a global perspective of the field and to outline directions for future work
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