161 research outputs found

    Effect of Nozzle Divergence Angle on Plume Expansion In Outer-Space Conditions

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    We carry out numerical simulations to investigate the effect of nozzle divergence angle on back flow of plume expansion into rarefied atmosphere. Results are obtained using open source compressible computational fluid dynamics (CFD) solver. Non-equilibrium slip and jump boundary conditions for velocity and temperature are implemented to capture rarefaction rarefaction effects in the slip flow regime. The solver has been validated with the experimental data for a nozzle flow in the slip flow regime. We explore the non-linear non-equilibrium gas flow physics of a supersonic jet expansion. We report results of pressure, heat and drag coefficients for different divergent angles ( 12 0 , 15 0 and 20 0 ) at 80 km altitude conditions. The slip based results for heat loads significantly under-predict the no-slip ones, while for pressure and drag coefficients, deviations are found to be minute. It is noticed that thrust coefficient of nozzle increases with increase in divergence angle, however, nozzle with divergent angle of 15 0 led to minimum drag and heat transfer load on the critical region. The current study is important from the perspective of the overall aero-thermodynamic design of a typical supersonic rocket model operating under rarefied conditions

    Ischemic stroke subtypes and migraine with visual aura in the ARIC study

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    OBJECTIVE: To investigate the association among migraine, ischemic stroke, and stroke subtypes in the Atherosclerosis Risk in Communities (ARIC) study. METHODS: In this ongoing, prospective, longitudinal community-based cohort study, participants were given an interview ascertaining migraine history in 1993-1995, and were followed for all vascular events, including stroke. All stroke events over the subsequent 20 years were adjudicated and classified into stroke subtypes by standard definitions. Cox proportional hazards models adjusted for stroke risk factors were used to study the relationship between migraine and ischemic stroke, overall, as well as stroke subtypes (cardioembolic, lacunar, or thrombotic). RESULTS: We identified 1,622 migraineurs among 12,758 participants. Mean age of the study population at the 3rd clinical visit was 59 years. When compared to nonheadache participants, there was a significant association between migraine with visual aura and ischemic stroke (hazard ratio [HR] 1.7, 95% confidence interval [CI] 1.2-2.6, p = 0.008). Migraine without visual aura was not significantly associated with ischemic stroke (HR 1.2, CI 1.0-1.8, p = 0.28) when compared to nonheadache participants. Among the 3 subtypes of ischemic stroke evaluated, migraine with visual aura was significantly associated only with cardioembolic stroke (HR 3.7, 95% CI 1.6-8.7, p = 0.003). CONCLUSION: In participants with migraine with visual aura in late middle age, increased risk of cardioembolic stroke was observed. Migraine with visual aura was linked to increased stroke risk, while migraine without visual aura was not, over the period of 20 years. These results are specific to older migraineurs

    Adapting the HHL algorithm to (non-unitary) quantum many-body theory

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    Rapid progress in developing near- and long-term quantum algorithms for quantum chemistry has provided us with an impetus to move beyond traditional approaches and explore new ways to apply quantum computing to electronic structure calculations. In this work, we identify the connection between quantum many-body theory and a quantum linear solver, and implement the Harrow-Hassidim-Lloyd (HHL) algorithm to make precise predictions of correlation energies for light molecular systems via the (non-unitary) linearised coupled cluster theory. We alter the HHL algorithm to integrate two novel aspects- (a) we prescribe a novel scaling approach that allows one to scale any arbitrary symmetric positive definite matrix A, to solve for Ax = b and achieve x with reasonable precision, all the while without having to compute the eigenvalues of A, and (b) we devise techniques that reduce the depth of the overall circuit. In this context, we introduce the following variants of HHL for different eras of quantum computing- AdaptHHLite in its appropriate forms for noisy intermediate scale quantum (NISQ), late-NISQ, and the early fault-tolerant eras, as well as AdaptHHL for the fault-tolerant quantum computing era. We demonstrate the ability of the NISQ variant of AdaptHHLite to capture correlation energy precisely, while simultaneously being resource-lean, using simulation as well as the 11-qubit IonQ quantum hardware

    Elevated TCA cycle function in the pathology of diet-induced hepatic insulin resistance and fatty liver

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    The manner in which insulin resistance impinges on hepatic mitochondrial function is complex. Although liver insulin resistance is associated with respiratory dysfunction, the effect on fat oxidation remains controversial, and biosynthetic pathways that traverse mitochondria are actually increased. The tricarboxylic acid (TCA) cycle is the site of terminal fat oxidation, chief source of electrons for respiration, and a metabolic progenitor of gluconeogenesis. Therefore, we tested whether insulin resistance promotes hepatic TCA cycle flux in mice progressing to insulin resistance and fatty liver on a high-fat diet (HFD) for 32 weeks using standard biomolecular and in vivo (2)H/(13)C tracer methods. Relative mitochondrial content increased, but respiratory efficiency declined by 32 weeks of HFD. Fasting ketogenesis became unresponsive to feeding or insulin clamp, indicating blunted but constitutively active mitochondrial β-oxidation. Impaired insulin signaling was marked by elevated in vivo gluconeogenesis and anaplerotic and oxidative TCA cycle flux. The induction of TCA cycle function corresponded to the development of mitochondrial respiratory dysfunction, hepatic oxidative stress, and inflammation. Thus, the hepatic TCA cycle appears to enable mitochondrial dysfunction during insulin resistance by increasing electron deposition into an inefficient respiratory chain prone to reactive oxygen species production and by providing mitochondria-derived substrate for elevated gluconeogenesis

    HPV transcript expression affects cervical cancer response to chemoradiation

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    Persistent HPV infection is causative for the majority of cervical cancer cases; however, current guidelines do not require HPV testing for newly diagnosed cervical cancer. Using an institutional cohort of 88 patients with cervical cancer treated uniformly with standard-of-care chemoradiation treatment (CRT) with prospectively collected clinical outcome data, we observed that patients with cervical tumors containing HPV genotypes other than HPV 16 have worse survival outcomes after CRT compared with patients with HPV 16+ tumors, consistent with previously published studies. Using RNA sequencing analysis, we quantified viral transcription efficiency and found higher levels of E6 and the alternative transcript E6*I in cervical tumors with HPV genotypes other than HPV 16. These findings were validated using whole transcriptome data from The Cancer Genome Atlas (n = 304). For the first time to our knowledge, transcript expression level of HPV E6*I was identified as a predictive biomarker of CRT outcome in our complete institutional data set (n = 88) and within the HPV 16+ subset (n = 36). In vitro characterization of HPV E6*I and E6 overexpression revealed that both induce CRT resistance through distinct mechanisms dependent upon p53-p21. Our findings suggest that high expression of E6*I and E6 may represent novel biomarkers of CRT efficacy, and these patients may benefit from alternative treatment strategies

    Dynamics of nanoscale droplets on moving surfaces

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    We use molecular dynamics (MD) simulations to investigate the dynamic wetting of nanoscale water droplets on moving surfaces. The density and hydrogen bonding profiles along the direction normal to the surface are reported, and the width of the water depletion layer is evaluated first for droplets on three different static surfaces: silicon, graphite, and a fictitious superhydrophobic surface. The advancing and receding contact angles, and contact angle hysteresis, are then measured as a function of capillary number on smooth moving silicon and graphite surfaces. Our results for the silicon surface show that molecular displacements at the contact line are influenced greatly by interactions with the solid surface and partly by viscous dissipation effects induced through the movement of the surface. For the graphite surface, however, both the advancing and receding contact angles values are close to the static contact angle value and are independent of the capillary number; i.e., viscous dissipation effects are negligible. This finding is in contrast with the wetting dynamics of macroscale water droplets, which show significant dependence on the capillary number

    CYLD Enhances Severe Listeriosis by Impairing IL-6/STAT3-Dependent Fibrin Production

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    The facultative intracellular bacterium Listeria monocytogenes (Lm) may cause severe infection in humans and livestock. Control of acute listeriosis is primarily dependent on innate immune responses, which are strongly regulated by NF-kappa B, and tissue protective factors including fibrin. However, molecular pathways connecting NF-kappa B and fibrin production are poorly described. Here, we investigated whether the deubiquitinating enzyme CYLD, which is an inhibitor of NF-kappa B-dependent immune responses, regulated these protective host responses in murine listeriosis. Upon high dose systemic infection, all C57BL/6 Cyld(-/-) mice survived, whereas 100% of wildtype mice succumbed due to severe liver pathology with impaired pathogen control and hemorrhage within 6 days. Upon in vitro infection with Lm, CYLD reduced NF-kappa B-dependent production of reactive oxygen species, interleukin (IL)-6 secretion, and control of bacteria in macrophages. Furthermore, Western blot analyses showed that CYLD impaired STAT3-dependent fibrin production in cultivated hepatocytes. Immunoprecipitation experiments revealed that CYLD interacted with STAT3 in the cytoplasm and strongly reduced K63-ubiquitination of STAT3 in IL-6 stimulated hepatocytes. In addition, CYLD diminished IL-6-induced STAT3 activity by reducing nuclear accumulation of phosphorylated STAT3. In vivo, CYLD also reduced hepatic STAT3 K63-ubiquitination and activation, NF-kappa B activation, IL-6 and NOX2 mRNA production as well as fibrin production in murine listeriosis. In vivo neutralization of IL-6 by anti-IL-6 antibody, STAT3 by siRNA, and fibrin by warfarin treatment, respectively, demonstrated that IL-6-induced, STAT3-mediated fibrin production significantly contributed to protection in Cyld(-/-) mice. In addition, in vivo Cyld siRNA treatment increased STAT3 phosphorylation, fibrin production, pathogen control and survival of Lm-infected WT mice illustrating that therapeutic inhibition of CYLD augments the protective NF-kappa B/IL-6/STAT3 pathway and fibrin production

    Climate change, malaria and neglected tropical diseases: a scoping review

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    To explore the effects of climate change on malaria and 20 neglected tropical diseases (NTDs), and potential effect amelioration through mitigation and adaptation, we searched for papers published from January 2010 to October 2023. We descriptively synthesised extracted data. We analysed numbers of papers meeting our inclusion criteria by country and national disease burden, healthcare access and quality index (HAQI), as well as by climate vulnerability score. From 42 693 retrieved records, 1543 full-text papers were assessed. Of 511 papers meeting the inclusion criteria, 185 studied malaria, 181 dengue and chikungunya and 53 leishmaniasis; other NTDs were relatively understudied. Mitigation was considered in 174 papers (34%) and adaption strategies in 24 (5%). Amplitude and direction of effects of climate change on malaria and NTDs are likely to vary by disease and location, be non-linear and evolve over time. Available analyses do not allow confident prediction of the overall global impact of climate change on these diseases. For dengue and chikungunya and the group of non-vector-borne NTDs, the literature privileged consideration of current low-burden countries with a high HAQI. No leishmaniasis papers considered outcomes in East Africa. Comprehensive, collaborative and standardised modelling efforts are needed to better understand how climate change will directly and indirectly affect malaria and NTDs
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