501 research outputs found
Steady and Unsteady Nozzle Simulations Using the Conservation Element and Solution Element Method
This paper presents results from computational fluid dynamic (CFD) simulations of a three-stream plug nozzle. Time-accurate, Euler, quasi-1D and 2D-axisymmetric simulations were performed as part of an effort to provide a CFD-based approach to modeling nozzle dynamics. The CFD code used for the simulations is based on the space-time Conservation Element and Solution Element (CESE) method. Steady-state results were validated using the Wind-US code and a code utilizing the MacCormack method while the unsteady results were partially validated via an aeroacoustic benchmark problem. The CESE steady-state flow field solutions showed excellent agreement with solutions derived from the other methods and codes while preliminary unsteady results for the three-stream plug nozzle are also shown. Additionally, a study was performed to explore the sensitivity of gross thrust computations to the control surface definition. The results showed that most of the sensitivity while computing the gross thrust is attributed to the control surface stencil resolution and choice of stencil end points and not to the control surface definition itself.Finally, comparisons between the quasi-1D and 2D-axisymetric solutions were performed in order to gain insight on whether a quasi-1D solution can capture the steady and unsteady nozzle phenomena without the cost of a 2D-axisymmetric simulation. Initial results show that while the quasi-1D solutions are similar to the 2D-axisymmetric solutions, the inability of the quasi-1D simulations to predict two dimensional phenomena limits its accuracy
Scalable Cross-lingual Document Similarity through Language-specific Concept Hierarchies
With the ongoing growth in number of digital articles in a wider set of
languages and the expanding use of different languages, we need annotation
methods that enable browsing multi-lingual corpora. Multilingual probabilistic
topic models have recently emerged as a group of semi-supervised machine
learning models that can be used to perform thematic explorations on
collections of texts in multiple languages. However, these approaches require
theme-aligned training data to create a language-independent space. This
constraint limits the amount of scenarios that this technique can offer
solutions to train and makes it difficult to scale up to situations where a
huge collection of multi-lingual documents are required during the training
phase. This paper presents an unsupervised document similarity algorithm that
does not require parallel or comparable corpora, or any other type of
translation resource. The algorithm annotates topics automatically created from
documents in a single language with cross-lingual labels and describes
documents by hierarchies of multi-lingual concepts from independently-trained
models. Experiments performed on the English, Spanish and French editions of
JCR-Acquis corpora reveal promising results on classifying and sorting
documents by similar content.Comment: Accepted at the 10th International Conference on Knowledge Capture
(K-CAP 2019
Sushi barcoding in the UK : another kettle of fish
Although the spread of sushi restaurants in the European Union and United States
is a relatively new phenomenon, they have rapidly become among the most popular
food services globally. Recent studies indicate that they can be associated with very
high levels (>70%) of fish species substitution. Based on indications that the European
seafood retail sector may currently be under better control than its North American
counterpart, here we investigated levels of seafood labelling accuracy in sushi bars and
restaurants across England. We used the COI barcoding gene to screen samples of tuna,
eel, and a variety of other products characterised by less visually distinctive `white flesh'.
Moderate levels of substitution were found (10%), significantly lower than observed in
North America, which lends support to the argument that public awareness, policy and
governance of seafood labels is more effective in the European Union. Nevertheless,
the results highlight that current labelling practice in UK restaurants lags behind the
level of detail implemented in the retail sector, which hinders consumer choice, with
potentially damaging economic, health and environmental consequences. Specifically,
critically endangered species of tuna and eel continue to be sold without adequate
information to consumers
Genome-wide Linkage Scan to Identify Loci for Age at First Cigarette in Dutch Sibling Pairs
Most smokers begin smoking during adolescence and early age of smoking initiation is related to more frequent current smoking, daily smoking and more dependent smoking (Everret et al., 1999; Lando et al.
How Do Honeybees Attract Nestmates Using Waggle Dances in Dark and Noisy Hives?
It is well known that honeybees share information related to food sources with nestmates using a dance language that is representative of symbolic communication among non-primates. Some honeybee species engage in visually apparent behavior, walking in a figure-eight pattern inside their dark hives. It has been suggested that sounds play an important role in this dance language, even though a variety of wing vibration sounds are produced by honeybee behaviors in hives. It has been shown that dances emit sounds primarily at about 250–300 Hz, which is in the same frequency range as honeybees' flight sounds. Thus the exact mechanism whereby honeybees attract nestmates using waggle dances in such a dark and noisy hive is as yet unclear. In this study, we used a flight simulator in which honeybees were attached to a torque meter in order to analyze the component of bees' orienting response caused only by sounds, and not by odor or by vibrations sensed by their legs. We showed using single sound localization that honeybees preferred sounds around 265 Hz. Furthermore, according to sound discrimination tests using sounds of the same frequency, honeybees preferred rhythmic sounds. Our results demonstrate that frequency and rhythmic components play a complementary role in localizing dance sounds. Dance sounds were presumably developed to share information in a dark and noisy environment
Chronic elevation of pulmonary microvascular pressure in chronic heart failure reduces bi-directional pulmonary fluid flux
Aims. Chronic heart failure leads to pulmonary vascular remodelling and thickening of the alveolar–capillary barrier. We examined whether this protective effect may slow resolution of pulmonary oedema consistent with decreased bi-directional fluid flux.
Methods and results. Seven weeks following left coronary artery ligation, we measured both fluid flux during an acute rise in left atrial pressure (n = 29) and intrinsic alveolar fluid clearance (n = 45) in the isolated rat lung. Chronic elevation of pulmonary microvascular pressure prevented pulmonary oedema and decreased lung compliance when left atrial pressure was raised to 20 cmH2O, and was associated with reduced expression of endothelial aquaporin 1 (P = 0.03). However, no other changes were found in mediators of fluid flux or cellular fluid channels. In isolated rat lungs, chronic LV dysfunction (LV end-diastolic pressure and infarct circumference) was also inversely related to alveolar fluid clearance (P ≤ 0.001). The rate of pulmonary oedema reabsorption was estimated by plasma volume expansion in eight patients with a previous clinical history of chronic heart failure and eight without, who presented with acute pulmonary oedema. Plasma volume expansion was reduced at 24 h in those with chronic heart failure (P = 0.03).
Conclusions. Chronic elevation of pulmonary microvascular pressure in CHF leads to decreased intrinsic bi-directional fluid flux at the alveolar–capillary barrier. This adaptive response defends against alveolar flooding, but may delay resolution of alveolar oedema.A National Health and Medical Research Council (NHMRC) grant (#375129); Australian and New Zealand College of Anaesthetists (ANZCA) grant (#08/020); the Flinders Medical Centre Foundation
Essential Noninvasive Multimodality Neuromonitoring for the Critically Ill Patient
This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2020. Other selected articles can be found online at . Further information about the Annual Update in Intensive Care and Emergency Medicine is available from
Validity of a new automated software program for visceral adipose tissue estimation
Introduction: Given the considerable time and research cost of analyzing biomedical images to quantify adipose tissue volumes, automated image analysis methods are highly desirable. Hippo Fatt is a new software program designed to automatically quantify adipose tissue areas from magnetic resonance images without user inputs. Hippo Fatt has yet to be independently validated against commonly used image analysis software programs. Objective: Our aim was to compare estimates of VAT (visceral adipose tissue) and SAT (subcutaneous adipose tissue) using the new Hippo Fatt software against those from a widely used, validated, computer-assisted manual method (slice-O-matic version 4.2, Tomovision, Montreal, CA, USA) to assess its potential utility for large-scale studies. Methods: A Siemens Magnetom Vision 1.5-T whole-body scanner and a T1-weighted fast-spin echo pulse sequence were used to collect multiple, contiguous axial images of the abdomen from a sample of 40 healthy adults (20 men) aged 18-77 years of age, with mean body mass index of 29 kg/m 2 (range ¼ 19-43 kg/m 2 ). Results: Hippo Fatt provided estimates of VAT and SAT that were highly correlated with estimates using slice-O-matic (R 2 40.9). Average VAT was 9.4% lower and average SAT was 3.7% higher using Hippo Fatt compared to slice-O-matic; the overestimation of SAT tended to be greater among individuals with greater adiposity. Individual-level differences for VAT were also substantial; Hippo Fatt gave estimates of VAT ranging from 1184 cm 3 less to 566 cm 3 more than estimates for the same person using slice-O-matic. Conclusion: Hippo Fatt provides a rapid method of quantifying total VAT, although the method does not provide estimates that are interchangeable with slice-O-matic at either the group (mean) or individual level
Collective Effects in the NSLS-II Storage Ring.
A new high-brightness synchrotron light source (NSLS-II) is under design at BNL. The 3-GeV NSLS-II storage ring has a double-bend achromatic lattice with damping wigglers installed in zero-dispersion straights to reduce the emittance below 1nm. In this paper, we present an overview of the impact of collective effects upon the performance of the storage ring. Subjects discussed include instability thresholds, Touschek lifetime and intra-beam scattering
Modulation of epithelial sodium channel (ENaC) expression in mouse lung infected with Pseudomonas aeruginosa
BACKGROUND: The intratracheal instillation of Pseudomonas aeruginosa entrapped in agar beads in the mouse lung leads to chronic lung infection in susceptible mouse strains. As the infection generates a strong inflammatory response with some lung edema, we tested if it could modulate the expression of genes involved in lung liquid clearance, such as the α, β and γ subunits of the epithelial sodium channel (ENaC) and the catalytic subunit of Na(+)-K(+)-ATPase. METHODS: Pseudomonas aeruginosa entrapped in agar beads were instilled in the lung of resistant (BalB/c) and susceptible (DBA/2, C57BL/6 and A/J) mouse strains. The mRNA expression of ENaC and Na(+)-K(+)-ATPase subunits was tested in the lung by Northern blot following a 3 hours to 14 days infection. RESULTS: The infection of the different mouse strains evoked regulation of α and β ENaC mRNA. Following Pseudomonas instillation, the expression of αENaC mRNA decreased to a median of 43% on days 3 and 7 after infection and was still decreased to a median of 45% 14 days after infection (p < 0.05). The relative expression of βENaC mRNA was transiently increased to a median of 241%, 24 h post-infection before decreasing to a median of 43% and 54% of control on days 3 and 7 post-infection (p < 0.05). No significant modulation of γENaC mRNA was detected although the general pattern of expression of the subunit was similar to α and β subunits. No modulation of α(1)Na(+)-K(+)-ATPase mRNA, the catalytic subunit of the sodium pump, was recorded. The distinctive expression profiles of the three subunits were not different, between the susceptible and resistant mouse strains. CONCLUSIONS: These results show that Pseudomonas infection, by modulating ENaC subunit expression, could influence edema formation and clearance in infected lungs
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