2,188 research outputs found
Water immersion for post incident cooling of firefighters; a review of practical fire ground cooling modalities
Rapidly cooling firefighters post emergency response is likely to increase the operational effectiveness of fire services during prolonged incidents. A variety of techniques have therefore been examined to return firefighters core body temperature to safe levels prior to fire scene re-entry or redeployment. The recommendation of forearm immersion (HFI) in cold water by the National Fire and Protection Association preceded implementation of this active cooling modality by a number of fire services in North America, South East Asia and Australia. The vascularity of the hands and forearms may expedite body heat removal, however, immersion of the torso, pelvis and/or lower body, otherwise known as multi-segment immersion (MSI), exposes a greater proportion of the body surface to water than HFI, potentially increasing the rates of cooling conferred. Therefore, this review sought to establish the efficacy of HFI and MSI to rapidly reduce firefighters core body temperature to safe working levels during rest periods. A total of 38 studies with 55 treatments (43 MSI, 12 HFI) were reviewed. The core body temperature cooling rates conferred by MSI were generally classified as ideal (n = 23) with a range of ~0.01 to 0.35 °C min−1. In contrast, all HFI treatments resulted in unacceptably slow core body temperature cooling rates (~0.01 to 0.05 °C min−1). Based upon the extensive field of research supporting immersion of large body surface areas and comparable logistics of establishing HFI or MSI, it is recommended that fire and rescue management reassess their approach to fireground rehabilitation of responders. Specifically, we question the use of HFI to rapidly lower firefighter core body temperature during rest periods. By utilising MSI to restore firefighter Tc to safe working levels, fire and rescue services would adopt an evidence based approach to maintaining operational capability during arduous, sustained responses. While the optimal MSI protocol will be determined by the specifics of an individual response, maximising the body surface area immersed in circulated water of up to 26 °C for 15 min is likely to return firefighter Tc to safe working levels during rest periods. Utilising cooler water temperatures will expedite Tc cooling and minimise immersion duration
3D-to-2D Transition of Anion Vacancy Mobility in CsPbBr<sub>3</sub>under Hydrostatic Pressure
We study the effects of hydrostatic pressure in the range 0.0--2.0 GPa on
anion mobility in the orthorhombic phase of CsPbBr. Using density
functional theory and the climbing nudged elastic band method, we calculate the
transition states and activation energies for anions to migrate both within and
between neighbouring PbBr octahedra. The results of those calculations
are used as input to a kinetic model for anion migration, which we solve in the
steady state to determine the anion mobility tensor as a function of applied
pressure. We find that the response of the mobility tensor to increasing
pressure is highly anisotropic, being strongly enhanced in the lattice
plane and strongly reduced in the direction normal to it at elevated pressure.
These results demonstrate the potentially significant influence of pressure and
strain on the magnitude and direction of anion migration in lead--halide
perovskites.Comment: 25 pages, 3 figure
The Nature of the Density Clump in the Fornax Dwarf Spheroidal Galaxy
We have imaged the recently discovered stellar overdensity located
approximately one core radius from the center of the Fornax dwarf spheroidal
galaxy using the Magellan Clay 6.5m telescope with the Magellan Instant Camera
(MagIC). Superb seeing conditions allowed us to probe the stellar populations
of this overdensity and of a control field within Fornax to a limiting
magnitude of R=26. The color-magnitude diagram of the overdensity field is
virtually identical to that of the control field with the exception of the
presence of a population arising from a very short (less than 300 Myr in
duration) burst of star formation 1.4 Gyr ago. Coleman et al. have argued that
this overdensity might be related to a shell structure in Fornax that was
created when Fornax captured a smaller galaxy. Our results are consistent with
this model, but we argue that the metallicity of this young component favors a
scenario in which the gas was part of Fornax itself.Comment: 24 pages including 8 figures and 3 tables. Accepted by Astronomical
Journa
The autism-linked UBE3A T485A mutant E3 ubiquitin ligase activates the Wnt/β-catenin pathway by inhibiting the proteasome
Projective Ribbon Permutation Statistics: a Remnant of non-Abelian Braiding in Higher Dimensions
In a recent paper, Teo and Kane proposed a 3D model in which the defects
support Majorana fermion zero modes. They argued that exchanging and twisting
these defects would implement a set R of unitary transformations on the zero
mode Hilbert space which is a 'ghostly' recollection of the action of the braid
group on Ising anyons in 2D. In this paper, we find the group T_{2n} which
governs the statistics of these defects by analyzing the topology of the space
K_{2n} of configurations of 2n defects in a slowly spatially-varying gapped
free fermion Hamiltonian: T_{2n}\equiv {\pi_1}(K_{2n})$. We find that the group
T_{2n}= Z \times T^r_{2n}, where the 'ribbon permutation group' T^r_{2n} is a
mild enhancement of the permutation group S_{2n}: T^r_{2n} \equiv \Z_2 \times
E((Z_2)^{2n}\rtimes S_{2n}). Here, E((Z_2)^{2n}\rtimes S_{2n}) is the 'even
part' of (Z_2)^{2n} \rtimes S_{2n}, namely those elements for which the total
parity of the element in (Z_2)^{2n} added to the parity of the permutation is
even. Surprisingly, R is only a projective representation of T_{2n}, a
possibility proposed by Wilczek. Thus, Teo and Kane's defects realize
`Projective Ribbon Permutation Statistics', which we show to be consistent with
locality. We extend this phenomenon to other dimensions, co-dimensions, and
symmetry classes. Since it is an essential input for our calculation, we review
the topological classification of gapped free fermion systems and its relation
to Bott periodicity.Comment: Missing figures added. Fixed some typos. Added a paragraph to the
conclusio
Bayesian parameter estimation for characterising mobile ion vacancies in perovskite solar cells
To overcome the challenges associated with poor temporal stability of
perovskite solar cells, methods are required that allow for fast iteration of
fabrication and characterisation, such that optimal device performance and
stability may be actively pursued. Currently, establishing the causes of
underperformance is both complex and time-consuming, and optimisation of device
fabrication thus inherently slow. Here, we present a means of computational
device characterisation of mobile halide ion parameters from room temperature
current-voltage (J-V) measurements only, requiring hours of
computation on basic computing resources. With our approach, the physical
parameters of the device may be reverse modelled from experimental J-V
measurements. In a drift-diffusion model, the set of coupled drift-diffusion
partial differential equations cannot be inverted explicitly, so a method for
inverting the drift-diffusion simulation is required. We show how Bayesian
Parameter Estimation (BPE) coupled with a drift-diffusion perovskite solar cell
model can determine the extent to which device parameters affect performance
measured by J-V characteristics. Our method is demonstrated by investigating
the extent to which device performance is influenced by mobile halide ions for
a specific fabricated device. The ion vacancy density and diffusion
coefficient were found to be precisely characterised for both simulated
and fabricated devices. This result opens up the possibility of pinpointing
origins of degradation by finding which parameters most influence device J-V
curves as the cell degrades
Wildlife-friendly farming benefits rare birds, bees and plants
Agricultural intensification is a leading cause of global biodiversity loss, especially for threatened and near-threatened species. One widely implemented response is ‘wildlife-friendly farming’, involving the close integration of conservation and extensive farming practices within agricultural landscapes. However, the putative benefits from this controversial policy are currently either unknown or thought unlikely to extend to rare and declining species. Here, we show that new, evidence-based approaches to habitat creation on intensively managed farmland in England can achieve large increases in plant, bee and bird species. In particular, we found that habitat enhancement methods designed to provide the requirements of sensitive target biota consistently increased the richness and abundance of both rare and common species, with 10-fold to greater than 100-fold more rare species per sample area than generalized conventional conservation measures. Furthermore, targeting landscapes of high species richness amplified beneficial effects on the least mobile taxa: plants and bees. Our results provide the first unequivocal support for a national wildlife-friendly farming policy and suggest that this approach should be implemented much more extensively to address global biodiversity loss. However, to be effective, these conservation measures must be evidence-based, and developed using sound knowledge of the ecological requirements of key species
Manganese catalysed synthesis of polyketones using hydrogen borrowing approach.
We report here a new method to make polyketones from the coupling of diketones and diols using a manganese pincer complex. The methodology allows us to access a new type of polyketone (polyarylalkylketone) containing aryl, alkyl, and ether functionalities bridging the gap between the two classes of commercially available polyketones – aliphatic polyketones and polyaryletherketones. Using this methodology, twelve new polyketones have been synthesized and characterised using various analytical techniques to understand their chemical, physical, morphological, and mechanical properties. Based on previous reports and our studies, we suggest that the polymerization occurs via a hydrogen-borrowing mechanism that involves the dehydrogenation of diols to dialdehyde followed by aldol condensation of dialdehyde with diketones to form chalcone derivatives and their subsequent hydrogenation to form polyarylalkylketones
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