A Computational Method for Combustion in High Speed Flows

A two-dimensional time-accurate numerical model to simulate complex reacting flowfields in chemical non-equilibrium is presented. The aim of this studyis to develop a computational tool which permits the analysis and the easy implementation of combustion phenomena for high speed flows. To construct an efficient numerical tool, while maintaining a reasonable accuracy, a semi-implicit numerical method was selected and verified for a hydrogen-air mixture. The numerical approach is based on a time-dependent, finite-volume integration of the governing equations suitably modified for chemical non-equilibrium. The evaluation of the reacting constants based on Gibbs free energy and the Van't Hoff equation allows a very easy implementation of the chemical model used, regardless of its complexity. Calculations were performed with adeguate temporal and spatial resolution for modeling the physical process for pratical calculation. Comparisons with numerical results are used for a verification of the numerical procedur

Characterization of the fecal microbiome in cats with inflammatory bowel disease or alimentary small cell lymphoma.

Feline chronic enteropathy (CE) is a common gastrointestinal disorder in cats and mainly comprises inflammatory bowel disease (IBD) and small cell lymphoma (SCL). Both IBD and SCL in cats share features with chronic enteropathies such as IBD and monomorphic epitheliotropic intestinal T-cell lymphoma in humans. The aim of this study was to characterize the fecal microbiome of 38 healthy cats and 27 cats with CE (13 cats with IBD and 14 cats with SCL). Alpha diversity indices were significantly decreased in cats with CE (OTU p = 0.003, Shannon Index p = 0.008, Phylogenetic Diversity p = 0.019). ANOSIM showed a significant difference in bacterial communities, albeit with a small effect size (P = 0.023, R = 0.073). Univariate analysis and LEfSE showed a lower abundance of facultative anaerobic taxa of the phyla Firmicutes (families Ruminococcaceae and Turicibacteraceae), Actinobacteria (genus Bifidobacterium) and Bacteroidetes (i.a. Bacteroides plebeius) in cats with CE. The facultative anaerobic taxa Enterobacteriaceae and Streptococcaceae were increased in cats with CE. No significant difference between the microbiome of cats with IBD and those with SCL was found. Cats with CE showed patterns of dysbiosis similar to those in found people with IBD

A Comparison Of Different Technologies For Thrust Vectoring In A Linear Aerospike

The aerospike nozzle represents an interesting technology for Single-Stage-To-Orbit vehicles because of its self-adapting capability. It is possible to get thrust vectoring capabilities in different ways. A straightforward solution consists in applying differential throttling to multiple combustion chambers which feed the nozzle. An alternative technology, which can be used in the presence of a common combustion chamber, is represented by fluidic thrust vectoring which requires the injection of a secondary flow from a slot on the wall. In this work, the flow field in a linear aerospike nozzle is numerically investigated by means of RANS simulations and both differential throttling and shock vectoring are studied. A parametric study is performed to evaluate the potential of the two technologies

A Two-Dimensional Analysis of the Flowfield and Performances of Linear Aerospikes During Differential Throttling

The performances of two linear aerospike nozzles, generated by truncating the same plug contour at 40% and 20% of its ideal length, are investigated numerically within a two-dimensional approximation and compared with each other. The nozzle geometry is a 2D representation, extracted from the CAD model of the actual nozzles under experimental investigation. In the working conditions studied here, the nozzle is throttled differentially, by setting different flow conditions on the upper and lower inlet, with the aim of generating thrust vectoring effects. The performances and flowfield of both aerospikes are investigated for values of the nozzle pressure ratio (npr) ranging from 3.7 up to the design condition (NPR=200), and for several levels of differential throttling. The CFD approach adopted is based on a two-dimensional RANS flow model. Comparisons between the numerical and experimental data are performed at two nozzle working conditions: without and with differential throttling. The numerical results are in good agreement with the experimental data. Moreover, the numerical simulations of the throttling case have shown a thrust deflection of about 5 degrees, with a differential pressure of approximately 10 percent

On Statistical Modeling of Sequencing Noise in High Depth Data to Assess Tumor Evolution

© 2017, Springer Science+Business Media, LLC, part of Springer Nature. One cause of cancer mortality is tumor evolution to therapy-resistant disease. First line therapy often targets the dominant clone, and drug resistance can emerge from preexisting clones that gain fitness through therapy-induced natural selection. Such mutations may be identified using targeted sequencing assays by analysis of noise in high-depth data. Here, we develop a comprehensive, unbiased model for sequencing error background. We find that noise in sufficiently deep DNA sequencing data can be approximated by aggregating negative binomial distributions. Mutations with frequencies above noise may have prognostic value. We evaluate our model with simulated exponentially expanded populations as well as data from cell line and patient sample dilution experiments, demonstrating its utility in prognosticating tumor progression. Our results may have the potential to identify significant mutations that can cause recurrence. These results are relevant in the pretreatment clinical setting to determine appropriate therapy and prepare for potential recurrence pretreatment

ACVIM consensus statement guidelines on diagnosing and distinguishing low-grade neoplastic from inflammatory lymphocytic chronic enteropathies in cats

BackgroundLymphoplasmacytic enteritis (LPE) and low-grade intestinal T cell lymphoma (LGITL) are common diseases in older cats, but their diagnosis and differentiation remain challenging.ObjectivesTo summarize the current literature on etiopathogenesis and diagnosis of LPE and LGITL in cats and provide guidance on the differentiation between LPE and LGITL in cats. To provide statements established using evidence-based approaches or where such evidence is lacking, statements based on consensus of experts in the field.AnimalsNone.MethodsA panel of 6 experts in the field (2 internists, 1 radiologist, 1 anatomic pathologist, 1 clonality expert, 1 oncologist) with the support of a human medical immunologist, was formed to assess and summarize evidence in the peer-reviewed literature and complement it with consensus recommendations.ResultsDespite increasing interest on the topic for clinicians and pathologists, few prospective studies were available, and interpretation of the pertinent literature often was challenging because of the heterogeneity of the cases. Most recommendations by the panel were supported by a moderate or low level of evidence. Several understudied areas were identified, including cellular markers using immunohistochemistry, genomics, and transcriptomic studies.Conclusions and clinical importanceTo date, no single diagnostic criterion or known biomarker reliably differentiates inflammatory lesions from neoplastic lymphoproliferations in the intestinal tract of cats and a diagnosis currently is established by integrating all available clinical and diagnostic data. Histopathology remains the mainstay to better differentiate LPE from LGITL in cats with chronic enteropathy

Temporal Variability of the Dominant Fecal Microbiota in Healthy Adult Cats

While shifts in gut microbiota have been studied in diseased states, the temporal variability of the microbiome in cats has not been widely studied. This study investigated the temporal variability of the feline dysbiosis index (DI) and the abundance of core bacterial groups in healthy adult cats. The secondary aim was to evaluate the relationship between the fecal abundance of Clostridium hiranonis and the fecal concentrations of unconjugated bile acids. A total of 142 fecal samples collected from 17 healthy cats were prospectively included: nine cats with weekly collection over 3 weeks (at least four time points), five cats with monthly collection over 2 months (three time points), and three cats with additional collections for up to 10 months. The DI remained stable within the reference intervals over two months for all cats (Friedman test, p > 0.2), and 100% of the DI values (n = 142) collected throughout the study period remained within the RI. While some temporal individual variation was observed for individual taxa, the magnitude was minimal compared to cats with chronic enteropathy and antibiotic exposure. Additionally, the abundance of Clostridium hiranonis was significantly correlated with the percentage of fecal primary bile acids, supporting its role as a bile acid converter in cats