208 research outputs found
Assessment of the release of atomic Na from a burning black liquor droplet using quantitative PLIF
The quantitative measurement of atomic sodium (Na) release, at high concentration, from a burning
black liquor droplet has been demonstrated using a planar laser-induced fluorescence (PLIF) technique,
corrected for fluorescence trapping. The local temperature of the particle was measured to be approximately
1700 C, at a height of 10 mm above a flat flame burner. The PLIF technique was used to assess
the temporal release of atomic Na from the combustion of black liquor and compare it with the Na concentration
in the remaining smelt. A first-order model was made to provide insight using a simple Plug
Flow Reactor model based on the independently measured concentration of residual Na in the smelt as a
function of time. This model also required the dilution ratio of the combustion products in the flat flame
entrained into the plume gas from the black liquor particle to be estimated. The key findings of these
studies are: (i) the peak concentration of atomic Na from the combustion of the black liquor droplets
is around 1.4 ppm; (ii) very little atomic Na is present during the drying, devolatilisation or char combustion
stages; and (iii) the presence of atomic Na during smelt phase dominates over that from the other
combustion stages
Effects of oxytocin on attention to emotional faces in healthy volunteers and highly socially anxious males
Background: Evidence suggests that individuals with social anxiety demonstrate vigilance to social threat, whilst the peptide hormone oxytocin is widely accepted as supporting affiliative behaviour in humans. Methods: This study investigated whether oxytocin can affect attentional bias in social anxiety. In a double-blind, randomized, placebo-controlled, within-group study design, 26 healthy and 16 highly socially anxious (HSA) male volunteers (within the HSA group, 10 were diagnosed with generalized social anxiety disorder) were administered 24 IU of oxytocin or placebo to investigate attentional processing in social anxiety. Attentional bias was assessed using the dot-probe paradigm with angry, fearful, happy and neutral face stimuli. Results: In the baseline placebo condition, the HSA group showed greater attentional bias for emotional faces than healthy individuals. Oxytocin reduced the difference between HSA and non-socially anxious individuals in attentional bias for emotional faces. Moreover, it appeared to normalize attentional bias in HSA individuals to levels seen in the healthy population in the baseline condition. The biological mechanisms by which oxytocin may be exerting these effects are discussed. Conclusions: These results, coupled with previous research, could indicate a potential therapeutic use of this hormone in treatment for social anxiety
Managing crop nutrients to achieve water quality goals
Landscapes and watersheds are inherently leaky and some nutrient loss can be expected with productive agricultural systems. Minimizing these losses, without undermining system sustainability is challenging and should involve an open and constructive discussion among all stakeholders as to what nutrient loss is desired, achievable, and how differences between these two endpoints can be reconciled. This is complicated by short- and long-term variations in weather/climate are a major factor influencing nutrient loss from agricultural lands. Nitrogen (N) loss tends to be spatially extensive, with management of the rate and timing of application, along with cropping systems as being important determining factors. Phosphorus (P) loss, on the other hand tends to be a function of critical sources areas, where coincident source (e.g., soil P and rate, timing, method and type of P applied) and transport factors (e.g., runoff and erosion) define losses. Despite this, legacy N and P from prior land management can mask the benefits of current and future conservation practices (CPs) to reduce losses from agricultural systems. Here, the appropriate use of calibrated and validated nonpoint source watershed models to estimate relative contributions of nutrient sources and outcomes of CP implementation can inform future strategies. However, they must be used in conjunction with and cannot replace water quality monitoring programs. Great strides have been made in nutrient use efficiency via nutrient management, crop selection, and CP adoption, which have reduced the risk of nutrient loss to surface and ground waters. Even so, additional research is needed on the areas of nutrient management on drained lands, fluvial legacies, and socio-economic factors influencing the success of conservation strategies
Two-loop corrections to the decay rate of parapositronium
Order corrections to the decay rate of parapositronium are
calculated. A QED scattering calculation of the amplitude for electron-positron
annihilation into two photons at threshold is combined with the technique of
effective field theory to determine an NRQED Hamiltonian, which is then used in
a bound state calculation to determine the decay rate. Our result for the
two-loop correction is in units of times the
lowest order rate. This is consistent with but more precise than the result
of a previous calculation.Comment: 26 pages, 7 figure
Active region formation through the negative effective magnetic pressure instability
The negative effective magnetic pressure instability operates on scales
encompassing many turbulent eddies and is here discussed in connection with the
formation of active regions near the surface layers of the Sun. This
instability is related to the negative contribution of turbulence to the mean
magnetic pressure that causes the formation of large-scale magnetic structures.
For an isothermal layer, direct numerical simulations and mean-field
simulations of this phenomenon are shown to agree in many details in that their
onset occurs at the same depth. This depth increases with increasing field
strength, such that the maximum growth rate of this instability is independent
of the field strength, provided the magnetic structures are fully contained
within the domain. A linear stability analysis is shown to support this
finding. The instability also leads to a redistribution of turbulent intensity
and gas pressure that could provide direct observational signatures.Comment: 19 pages, 10 figures, submitted to Solar Physic
The structure of a major surface antigen SAG19 from Eimeria tenella unifies the Eimeria SAG family
In infections by apicomplexan parasites including Plasmodium, Toxoplasma gondii, and Eimeria, host interactions are mediated by proteins including families of membrane-anchored cysteine-rich surface antigens (SAGs) and SAG-related sequences (SRS). Eimeria tenella causes caecal coccidiosis in chickens and has a SAG family with over 80 members making up 1% of the proteome. We have solved the structure of a representative E. tenella SAG, EtSAG19, revealing that, despite a low level of sequence similarity, the entire Eimeria SAG family is unified by its three-layer αβα fold which is related to that of the CAP superfamily. Furthermore, sequence comparisons show that the Eimeria SAG fold is conserved in surface antigens of the human coccidial parasite Cyclospora cayetanensis but this fold is unrelated to that of the SAGs/SRS proteins expressed in other apicomplexans including Plasmodium species and the cyst-forming coccidia Toxoplasma gondii, Neospora caninum and Besnoitia besnoiti. However, despite having very different structures, Consurf analysis showed that Eimeria SAG and Toxoplasma SRS families each exhibit marked hotspots of sequence hypervariability that map to their surfaces distal to the membrane anchor. This suggests that the primary and convergent purpose of the different structures is to provide a platform onto which sequence variability can be imposed
Tea drinking and cognitive function in oldest-old Chinese
10.1007/s12603-012-0077-1The Journal of Nutrition, Health & Aging169754-75
On the relative positions of the peaks in Raman and tunneling spectra of d-wave superconductors
We study Raman intensity and the density of states
in isotropic 2D d-wave superconductors. For an ideal gas,
and have sharp peaks at and , respectively, where is the maximum value of the gap.
We study how the peak positions are affected by the fermionic damping due to
impurity scattering.
We show that while the damping generally shifts the peak positions to larger
frequencies, the peak in still occurs at almost twice the peak
position in and therefore cannot account for the experimentally
observed downturn shift of the peak frequency in in underdoped
cuprates compared to twice that in . We also discuss how the
fermionic damping affects the dynamical spin susceptibility.Comment: 5 pages, 2 figure
A Burkholderia pseudomallei toxin inhibits helicase activity of translation factor eIF4A
The structure of BPSL1549, a protein of unknown function from Burkholderia pseudomallei, reveals a similarity to Escherichia coli cytotoxic necrotizing factor 1. We found that BPSL1549 acted as a potent cytotoxin against eukaryotic cells and was lethal when administered to mice. Expression levels of bpsl1549 correlate with conditions expected to promote or suppress pathogenicity. BPSL1549 promotes deamidation of glutamine-339 of the translation initiation factor eIF4A, abolishing its helicase activity and inhibiting translation. We propose to name BPSL1549 Burkholderia lethal factor 1
Irish cardiac society - Proceedings of annual general meeting held 20th & 21st November 1992 in Dublin Castle
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