The importance of social worlds: an investigation of peer relationships [Wider Benefits of Learning Research Report No. 29]

In the following report, we investigate the developing social worlds in late primary school, exploring the patterns in children’s general peer relationships, their closer and more significant friendships and bullying behaviours. Using cluster analysis, we identify unique groups of children characterized not only by their experiences of bullying and victimization, but the support and satisfaction they receive from their friendships and interactions between the ages of 8 and 10. We also expand past research by examining how children’s early development (ages 3 to 4) may predict their later designation as bullies and/or victims, and whether peer clusters relate to children’s contemporaneous and later adjustment

Thermochemistry of Grenfell Tower fire disaster: catastrophic effects of water as an 'extinguisher' in aluminium conflagrations

We review the thermochemistry of combustion reactions involved in the Grenfell Tower fire that occurred during the early hours of 14thJune 2017. London Fire Brigade (LFB), having advised all the occupants to stay in their apartments, attempted to extinguish the fire with water. The Grenfell Tower 24-storey block had recently been re-clad with an insulationto meet energy saving targets.It comprised an aluminum exterior façade, and a polymer composite thermal insulator ‘sandwich filler’, mainly polyethylene, with narrow air gaps inbetween polymer and aluminium sheets.The renovated window frames were also made of aluminum coated with a powdered polyester. Here, we highlight the scientific thermochemical reasonswhy water should never be used on aluminum fires; not least because a mixture of aluminium and water is a NASA rocket fuel! When the plastic insulation initially catches fire and burns with limited oxygen (O2 in air) to carbon(C), seen as an aerosol (black smoke) and black residue, the heat of reaction melts the aluminum(Al)and increases its fluidity and volatility, hence also its reactivity,whence it rapidly reacts with the carbon product of polymer combustion to form aluminum carbide (Al4C3). The heat of formation of Al4Cl3 is so great that it becomes white hot sparks like fireworks. At very high temperatures, both molten Al and Al4C3 aerosol react violently with water to give alumina fine dust aerosol(Al2O3)+ hydrogen (H2) gas and methane (CH4) gas, respectively, with white smoke and residues. These highly inflammable gases, with low spontaneous combustion temperatures, instantaneously react with the oxygen in air accelerating the fire out of control. Adding water to an aluminum fire is like adding “rocketfuel” to the existing flames. The timeline of events and photographic evidence corroborates this scientific explanation why a 4th-floor kitchen-appliance fire became a major tower-block inferno within 12minutes of applying water as a would-be extinguisher. A CO2-foam/powderextinguisher, as deployed in the aircraft industry against aluminum+plastic fires by smothering, might have contained the fire in its early stages. Thermochemistry of Grenfell Tower Fire Disasterinfo:eu-repo/semantics/publishedVersio

Thermodynamics of tower-block infernos: effects of water on aluminum fires

We review the thermodynamics of combustion reactions involved in aluminum fires in the light of the spate of recent high-profile tower-block disasters, such as the Grenfell fire in London 2017, the Dubai fires between 2010 and 2016, and the fires and explosions that resulted in the 9/11 collapse of the World Trade Center twin towers in New York. These fires are class B, i.e., burning metallic materials, yet water was applied in all cases as an extinguisher. Here, we highlight the scientific thermochemical reasons why water should never be used on aluminum fires, not least because a mixture of aluminum and water is a highly exothermic fuel. When the plastic materials initially catch fire and burn with limited oxygen (O2 in air) to carbon (C), which is seen as an aerosol (black smoke) and black residue, the heat of the reaction melts the aluminum (Al) and increases its fluidity and volatility. Hence, this process also increases its reactivity, whence it rapidly reacts with the carbon product of polymer combustion to form aluminum carbide (Al4C3). The heat of formation of Al4Cl3 is so great that it becomes white-hot sparks that are similar to fireworks. At very high temperatures, both molten Al and Al4C3 aerosol react violently with water to give alumina fine dust aerosol (Al2O3) + hydrogen (H2) gas and methane (CH4) gas, respectively, with white smoke and residues. These highly inflammable gases, with low spontaneous combustion temperatures, instantaneously react with the oxygen in the air, accelerating the fire out of control. Adding water to an aluminum fire is similar to adding "rocket fuel" to the existing flames. A CO2-foam/powder extinguisher, as deployed in the aircraft industry against aluminum and plastic fires by smothering, is required to contain aluminum fires at an early stage. Automatic sprinkler extinguisher systems should not be installed in tower blocks that are at risk of aluminum fires.info:eu-repo/semantics/publishedVersio

Thermal and structural tests of Rene 41 honeycomb integral-tank concept for future space transportation systems

Two flat 12 by 72 inch Rene 41 honeycomb sandwich panels were tested in a manner to produce combined thermal and mechanical longitudinal stresses that simulated those that would occur in a larger, more complex integral tank and fuselage structure of an earth to orbit vehicle. Elastic strains measured at temperatures below 400 F are compared with calculated values obtained from a linear elastic finite element analysis to verify the analytical model and to establish confidence in the calculated strains. Elastic strain measurement at higher temperatures (between 600 F and 1400 F), where strain measurement is more difficult and less certain, are also compared with calculated strains. Agreement between measured and calculated strains for the lower temperatures is good, but agreement for the higher temperatures is poor because of unreliable strain measurements. Test results indicate that an ascent and entry life cycle of 500 is attainable under high combined thermal and mechanical elastic strains

Strain Genotypes of Gibberella fujikuroi mating population A (Fusarium moniliforme) Mapping Population

Genetic maps are useful for researchers outside the originating laboratory only if the strains and markers used in the analysis of the mapping population and the genotypes of the strains composing the mapping population are available for analysis. This brief communication gives the genotypes for the strains that compose a recently constructed mapping population of G. fujikuroi. Strains and probes are available from FGSC

A Flattened Protostellar Envelope in Absorption around L1157

Deep Spitzer IRAC images of L1157 reveal many of the details of the outflow and the circumstellar environment of this Class 0 protostar. In IRAC band 4, 8 microns, there is a flattened structure seen in absorption against the background emission. The structure is perpendicular to the outflow and is extended to a diameter of 2 arcminutes. This structure is the first clear detection of a flattened circumstellar envelope or pseudo-disk around a Class 0 protostar. Such a flattened morphology is an expected outcome for many collapse theories that include magnetic fields or rotation. We construct an extinction model for a power-law density profile, but we do not constrain the density power-law index.Comment: ApJL accepte

Faint Stars in the Ursa Minor Dwarf Spheroidal Galaxy: Implications for the Low-Mass Stellar Initial Mass Function at High Redshift

The stellar initial mass function at high redshift is an important defining property of the first stellar systems to form and may also play a role in various dark matter problems. We here determine the faint stellar luminosity function in an apparently dark-matter-dominated external galaxy in which the stars formed at high redshift. The Ursa Minor dwarf spheroidal galaxy is a system with a particularly simple stellar population - all of the stars being old and metal-poor - similar to that of a classical halo globular cluster. A direct comparison of the faint luminosity functions of the UMi Sph and of similar metallicity, old globular clusters is equivalent to a comparison of the initial mass functions and is presented here, based on deep HST WFPC2 and STIS imaging data. We find that these luminosity functions are indistinguishable, down to a luminosity corresponding to 0.3 solar masses. Our results show that the low-mass stellar IMF for stars that formed at very high redshift is apparently invariant across environments as diverse as those of an extremely low-surface-brightness, dark-matter-dominated dwarf galaxy and a dark-matter-free, high-density globular cluster within the Milky Way.Comment: Accepted by New Astronomy. 64 pages, including 9 embedded postscript tables and 20 embedded postscript figures, plus 14 separate jpeg figures. Postscript versions of the jpeg figures and a complete version of the paper with all figures embedded can be found at http://tarkus.pha.jhu.edu/~mlh