Reduction of nitric oxide emissions from a combustor

A turbojet combustor and method for controlling nitric oxide emissions by employing successive combustion zones is described. After combustion of an initial portion of the fuel in a primary combustion zone, the combustion products of the primary zone are combined with the remaining portion of fuel and additional plenum air and burned in a secondary combustion zone under conditions that result in low nitric oxide emissions. Low nitric oxide emissions are achieved by a novel turbojet combustor arrangement which provides flame stability by allowing stable combustion to be accompanied by low nitric oxide emissions resulting from controlled fuel-lean combustion (ignited by the emission products from the primary zone) in a secondary combustion zone at a lower combustion temperature resulting in low emission of nitric oxide

Distinguishing models of reionization using future radio observations of 21-cm 1-point statistics

We explore the impact of reionization topology on 21-cm statistics. Four reionization models are presented which emulate large ionized bubbles around over-dense regions (21CMFAST/ global-inside- out), small ionized bubbles in over-dense regions (local-inside-out), large ionized bubbles around under-dense regions (global-outside-in) and small ionized bubbles around under-dense regions (local-outside-in). We show that first-generation instruments might struggle to distinguish global models using the shape of the power spectrum alone. All instruments considered are capable of breaking this degeneracy with the variance, which is higher in outside-in models. Global models can also be distinguished at small scales from a boost in the power spectrum from a positive correlation between the density and neutral-fraction fields in outside-in models. Negative skewness is found to be unique to inside-out models and we find that pre-SKA instruments could detect this feature in maps smoothed to reduce noise errors. The early, mid and late phases of reionization imprint signatures in the brightness-temperature moments, we examine their model dependence and find pre-SKA instruments capable of exploiting these timing constraints in smoothed maps. The dimensional skewness is introduced and is shown to have stronger signatures of the early and mid-phase timing if the inside-out scenario is correct.Comment: 18 pages, 13 figures, updated to agree with published versio

The impact of spin temperature fluctuations on the 21-cm moments

This paper considers the impact of Lyman-alpha coupling and X-ray heating on the 21-cm brightness-temperature one-point statistics (as predicted by semi-numerical simulations). The X-ray production efficiency is varied over four orders of magnitude and the hardness of the X-ray spectrum is varied from that predicted for high-mass X-ray binaries, to the softer spectrum expected from the hot inter-stellar medium. We find peaks in the redshift evolution of both the variance and skewness associated with the efficiency of X-ray production. The amplitude of the variance is also sensitive to the hardness of the X-ray SED. We find that the relative timing of the coupling and heating phases can be inferred from the redshift extent of a plateau that connects a peak in the variance's evolution associated with Lyman-alpha coupling to the heating peak. Importantly, we find that late X-ray heating would seriously hamper our ability to constrain reionization with the variance. Late X-ray heating also qualitatively alters the evolution of the skewness, providing a clean way to constrain such models. If foregrounds can be removed, we find that LOFAR, MWA and PAPER could constrain reionization and late X-ray heating models with the variance. We find that HERA and SKA (phase 1) will be able to constrain both reionization and heating by measuring the variance using foreground-avoidance techniques. If foregrounds can be removed they will also be able to constrain the nature of Lyman-alpha coupling.Comment: 16 pages, 13 figure, 1 table. Accepted for publication in MNRA

Rewriting the Constitution: An Economic Analysis of the Constitutional Amendment Process

In this Article, the authors develop an economic theory of the constitutional amendment process under Article V, focusing particularly on the roles that Congress and interest groups play in that process. The authors construct a model to predict when an interest group will seek an amendment rather than a statute to further its interests, highlighting how interest group maintenance costs and anticipated opposition affect that choice. They then discuss the efficiency goals of constitutionalism—precommitment and reduction of agency costs—and argue that the structure of the amendment process under Article V prevents realization of these goals. The authors contrast the Bill of Rights amendments, which established precommitments and reduced the agency costs of government, with the latter seventeen amendments, which expanded the federal government and increased agency costs. They attribute the change in the nature of the amendments to the interest-group domination of the political process and Congress\u27 control over the constitutional amendment agenda. The authors conclude that the Founders\u27 intent to put the Constitution beyond the reach of factions backfired: although factions cannot control the content of the Constitution, neither can the majority. In fact, Article V prevents the majority from precommiting itself and hinders its ability to control the agency costs of government, as evidenced by the history of the failed amendments. Although the authors conclude that Article V thwarts the efficiency goals of constitutionalism, they predict that little can be done to remedy this flaw

Gradient methods in control theory. Part 2 - Sequential gradient-restoration algorithm

Sequential gradient-restoration algorith

Autopilot? A reflexive review of the piloting process in qualitative e-research

Purpose: This paper examines an oft-neglected aspect of qualitative research practice – conducting a pilot – using the innovative approach of ‘e-research’ to generate both practical and methodological insights. Approach: Using the authors’ ‘e-research’ pilot as a reflexive case study, key methodological issues are critically reviewed. This review is set in a broader context of the qualitative methods literature in which piloting appears largely as an implicit practice. Using a new and emerging approach (‘e-research’) provides a prompt to review our ‘autopilot’ tendencies and offers a new lens for analysing research practice. Findings: We find that despite an initial focus on ‘practical’ aspects of data collection within our ‘e-research’, the pilot opened up a range of areas for further consideration. We review research ethics, collaborative research practices and data management issues specifically for e-research but also reflect more broadly on potential implications for piloting within other research designs. Practical implications: We aim to offer both practical and methodological insights for qualitative researchers, whatever their methodological orientation, so that they might develop approaches for piloting that are appropriate to their own research endeavours. More specifically, we offer tentative guidance to those venturing into the emerging area of ‘e-research’. Value: This paper offers insight into an oft-ignored aspect of qualitative research, whilst also engaging in emerging area of methodological interest

21-cm signatures of residual HI inside cosmic HII regions during reionization

We investigate the impact of sinks of ionizing radiation on the reionization-era 21-cm signal, focusing on 1-point statistics. We consider sinks in both the intergalactic medium and inside galaxies. At a fixed filling factor of HII regions, sinks will have two main effects on the 21-cm morphology: (i) as inhomogeneous absorbers of ionizing photons they result in smaller and more widespread cosmic HII patches; and (ii) as reservoirs of neutral gas they contribute a non-zero 21-cm signal in otherwise ionized regions. Both effects damp the contrast between neutral and ionized patches during reionization, making detection of the epoch of reionization with 21-cm interferometry more challenging. Here we systematically investigate these effects using the latest semi-numerical simulations. We find that sinks dramatically suppress the peak in the redshift evolution of the variance, corresponding to the midpoint of reionization. As previously predicted, skewness changes sign at midpoint, but the fluctuations in the residual HI suppress a late-time rise. Furthermore, large levels of residual HI dramatically alter the evolution of the variance, skewness and power spectrum from that seen at lower levels. In general, the evolution of the large-scale modes provides a better, cleaner, higher signal-to-noise probe of reionization.Comment: Minor edits to agree with MNRAS published versio

Immune Responses in Human Necatoriasis: Association between Interleukin-5 Responses and Resistance to Reinfection

Cytokine and proliferative responses to Necator americanus infection were measured in a treatment-reinfection study of infected subjects from an area of Papua New Guinea where N. americanus is highly endemic. Before treatment, most subjects produced detectable interleukin (IL)4 (97%), IL-5 (86%), and interferon (IFN)-γ(64%) in response to adult N. americanus antigen. Pretreatment IFN-γ responses were negatively associated with hookworm burden, decreasing by 18 pg/mL for each increase of 1000 eggs/gram (epg) (n = 75; P < .01). Mean IFN-γ responses increased significantly after anthelmintic treatment, from 166 to 322 pg/mL (n = 42; P < .01). The intensity of reinfection was significantly negatively correlated with pretreatment IL-5 responses, decreasing by 551 epg for each 100 pg/mL increase in production of IL-5 (n = 51; P < .01). These data indicate that there is a mixed cytokine response in necatoriasis, with worm burdenassociated suppression of IFN-γ responses to adult N. americanus antigen. Resistance to reinfection is associated with the parasite-specific IL-5 response