On the bi-stable nature of turbulent premixed bluff-body stabilized flames at elevated pressure and near lean blow-off

This study considers turbulent premixed bluff-body stabilized flames at elevated pressures. Specifically, the lean blow-off (LBO) limit of such flames is determined for a range of bulk velocities (5 U 50m/s) and operating pressures up to 3 bar. Two key observations emerge from this stability assessment. The first is that considering elevated pressure leads to two stability regimes: one at atmospheric conditions and those with elevated pressure and U & 20m/s (regime-a), and another at elevated pressures with U . 20m/s (regime-b). The second observation is that within these regimes, LBO limits are insensitive to pressure. Flames in regime-a (S-flames) are found to be more stable than those in regime-b (U-flames). Advanced image-based diagnostics were employed to understand reasons for this difference in stability. Flow field measurements indicate that U-flames are associated with an outer recirculation zone (ORZ) that formed as pressure increased but receded from the burner as U surpassed 20m/s. PLIF images of CH2O and OH demonstrated that the ORZ interacts with U-flames such that their downstream regions are prevented from collapsing to the inner recirculation zone (IRZ). Furthermore, analysis of the OH-PLIF images indicate that U-flames possess larger turbulent consumption rates, helping them form large IRZs and rendering them more susceptible to influence from the ORZ. Results of highspeed OH∗ imaging demonstrate that LBO events differ between U- and Sflames. Namely, while S-flames collapse to their IRZs during LBO, U-flames lift off from the burner, depleting their anchoring regions of reactions and hot products. Losing back-support in this region is what ultimately reduces the stability of U-flames. Finally, the reason U-flames lift off from the burner during LBO is elucidated by joint flow-flame measurements. Specifically, the anchoring regions of U-flames reside in regions of large axial velocity, which likely stems from their enhanced burning rates.No fundin

Characterization of biochar from rice hulls and wood chips produced in a top-lit updraft biomass gasifier

Citation: James, M., Yuan, W., Boyette, M. D., Wang, D., & Kumar, A. (2016). Characterization of biochar from rice hulls and wood chips produced in a top-lit updraft biomass gasifier. Transactions of the Asabe, 59(3), 749-756. doi:10.13031/trans.59.11631The objective of this study was to characterize biochar produced from rice hulls and wood chips in a top-lit updraft gasifier. Biochar from four airflows (8, 12, 16, or 20 L min-1) and two insulation conditions (not insulated or insulated with 88.9 mm of fiberglass on the external wall of the gasifier) were evaluated. Measurement of elemental composition, higher heating value (HHV), and BET surface area and proximate analyses of the biochar were carried out. It was found that the airflow rate and reactor insulation significantly influenced the chemical composition of the biochar depending on the biomass type. For instance, the carbon content of biochar from rice hulls decreased from 40.9% to 27.2% and the HHV decreased from 14.8 to 10.2 MJ kg-1 as the airflow increased from 8 to 20 L min-1 when the reactor was insulated. In contrast, the carbon content of biochar from wood chips increased from 82% to 86% and the HHV stayed stable at 32.0 to 33.2 MJ kg-1 at the same conditions. Despite these variations, the BET surface area of biochar from both biomass types increased with increased airflow and additional insulation. For example, rice hull biochar had a maximum BET surface area of 183 m2g-1 at 20 L min-1 airflow with insulation. The BET surface of biochar from wood chips peaked at 405 m2 gg-1 at the same conditions

Annual Survey of Virginia Law: Employment Law

This survey covers judicial and legislative developments in Virginia employment law between June 1988 and June 1989. The survey does not address judicial and legislative developments in the areas of workers\u27 compensation or unemployment compensation

Pathways from speech illusions to psychotic symptoms in subjects at Ultra-High Risk for psychosis: combining an experimental measure of aberrant experiences with network analysis

Background One of the oldest and most influential theories of psychosis formation states that delusions arise in an attempt to explain unusual experiences, including perceptual aberrations. The White Noise Task by Galdos et al (2011) was developed as an experimental task to assess the tendency to attribute meaning to random perceptual stimuli: speech illusions in white noise. Studies to date have demonstrated that speech illusions as assessed with the White Noise Task are associated with a composite measure of positive symptoms in patients with psychotic disorders (Galdos et al, 2011; Catalan et al, 2014). However, findings in non-clinical samples have been inconsistent: one study found an association with a composite measure of subclinical positive symptoms, including support for a relation with familial psychosis liability (Galdos et al, 2011), whereas other studies did not find any association in non-clinical samples or only partly (Catalan et al, 2014; Rimvall et al, 2016; Pries et al, 2017). The current study aims to further examine whether speech illusions as assessed with the White Noise Task are indicative of psychosis liability and to explore specific symptomatic pathways. Methods We conducted symptom-based network analyses in Ultra-High Risk (UHR) subjects participating in the European network of national networks studying gene-environment interactions in schizophrenia project (EU-GEI, 2014; www.eu-gei.eu). Psychotic symptoms were assessed with the Brief Psychiatric Rating Scale (BPRS). Transition to clinical psychosis was assessed with the Comprehensive Assessment of At Risk Mental State (CAARMS). We used a conservative measure of speech illusions, as described in Catalan et al (2014). Results The current sample consisted of 339 UHR subjects, of which 9.1% (N=31) experienced speech illusions. Preliminary network analyses in cross-sectional baseline data showed potential pathways from speech illusions to delusional ideation, through hallucinatory experiences. We also found evidence of prospective relations between speech illusions at baseline and transition to clinical psychosis. Pathways ran via baseline psychotic symptoms and affective symptoms, as well as a ‘direct’ pathway. Discussion As far as we are aware, this is the first study combining an experimental measure of aberrant experiences with symptom-based network analysis. Although the current reported findings are preliminary and exploratory, they tentatively support a relation between speech illusions as assessed with the White Noise Task and psychosis liability. This relation may be dependent on sample composition, and not generalizable to the general population as a whole. Future studies may benefit from focusing on more detailed trajectories of both susceptibility to speech illusions and course of (sub)clinical psychotic symptom severity in subjects with increased risk for psychosis, with use of more frequent, short assessment periods and inclusion of environmental risk factors for transition to clinical disorder

Mothers' and fathers' joint profiles for testosterone and oxytocin in a small‐scale fishing‐farming community: Variation based on marital conflict and paternal contributions

Introduction: Testosterone and oxytocin are psychobiological mechanisms that interrelate with relationship quality between parents and the quantity and quality of parenting behaviors, thereby affecting child outcomes. Their joint production based on family dynamics has rarely been tested, particularly cross‐culturally. Methods: We explored family function and salivary testosterone and oxytocin in mothers and fathers in a small‐scale, fishing‐farming society in Republic of the Congo. Fathers ranked one another in three domains of family life pertaining to the local cultural model of fatherhood. Results: Fathers who were viewed as better providers had relatively lower oxytocin and higher testosterone than men seen as poorer providers, who had lower testosterone and higher oxytocin. Fathers also had higher testosterone and lower oxytocin in marriages with more conflict, while those who had less marital conflict had reduced testosterone and higher oxytocin. In contrast, mothers in conflicted marriages showed the opposite profiles of relatively lower testosterone and higher oxytocin. Mothers had higher oxytocin and lower testosterone if fathers were uninvolved as direct caregivers, while mothers showed an opposing pattern for the two hormones if fathers were seen as involved with direct care. Conclusions: These results shed new light on parents' dual oxytocin and testosterone profiles in a small‐scale society setting and highlight the flexibility of human parental psychobiology when fathers' roles and functions within families differ across cultures

A randomised controlled trial comparing graded exercise treatment and usual physiotherapy for patients with non-specific neck pain (the GET UP neck pain trial).

Evidence supports exercise-based interventions for the management of neck pain, however there is little evidence of its superiority over usual physiotherapy. This study investigated the effectiveness of a group neck and upper limb exercise programme (GET) compared with usual physiotherapy (UP) for patients with non-specific neck pain. A total of 151 adult patients were randomised to either GET or UP. The primary measure was the Northwick Park Neck pain Questionnaire (NPQ) score at six weeks, six months and 12 months. Mixed modelling identified no difference in neck pain and function between patients receiving GET and those receiving UP at any follow-up time point. Both interventions resulted in modest significant and clinically important improvements on the NPQ score with a change score of around 9% between baseline and 12 months. Both GET and UP are appropriate clinical interventions for patients with non-specific neck pain, however preferences for treatment and targeted strategies to address barriers to adherence may need to be considered in order to maximise the effectiveness of these approaches

Drivers of diatom production and the legacy of eutrophication in two river plume regions of the northern Gulf of Mexico

In the northern Gulf of Mexico (nGoM), the Louisiana Shelf (LS) and Mississippi Bight (MB) subregions are influenced by eutrophication to varying degrees. Despite recognition that dissolved silicon may regulate diatom productivity in the nGoM, there is only one published data set reporting biogenic silica (bSiO2) production rates for each subregion. We report that bSiO2 production rates on the LS and MB are high and appear to be controlled by different nutrients among seasons. Despite exceptional upper trophic level biomass regionally, which suggests significant primary production by diatoms (as in other systems), gross euphotic-zone integrated bSiO2 production rates are lower than major bSiO2 producing regions (e.g. upwelling systems). However, when normalizing to the depth of the euphotic zone, the bSiO2 production rates on the LS are like normalized rates in upwelling systems. We suggest local river-plume influenced hydrography concentrates diatom productivity within shallow euphotic zones, making production more accessible to higher trophic organisms. Comparison of rates between the LS and MB suggest that the fluvial nitrate within the LS stimulates bSiO2 production above that in the MB, which has a smaller watershed and is less eutrophic (relatively). Beyond understanding the factors controlling regional bSiO2 production, these data offer the most comprehensive Si-cycle baseline to date as the LS and MB will likely exchange freely in the mid to late century due to land subsidence of the Mississippi River delta and/or sea-level rise