2,182 research outputs found
Why don't zombies like hibiscus tea? A multi-subject approach to photosynthesis through the use of Grätzel cells
Traditionally, photosynthesis has been seen as the domain of biology, with some input from chemistry when dealing with chromatography, while, apart from a passing reference to the colour of leaves, physics has tended to steer clear of the process that provides the lifeblood of human existence. This article outlines how a recent technological advance can be used as a teaching resource in all three branches of science
Buoyancy-driven inflow to a relic cold core: the gas belt in radio galaxy 3C 386
We report measurements from an XMM-Newton observation of the low-excitation
radio galaxy 3C 386. The study focusses on an X-ray-emitting gas belt, which
lies between and orthogonal to the radio lobes of 3C 386 and has a mean
temperature of keV, cooler than the extended group atmosphere.
The gas in the belt shows temperature structure with material closer to the
surrounding medium being hotter than gas closer to the host galaxy. We suggest
that this gas belt involves a `buoyancy-driven inflow' of part of the group-gas
atmosphere where the buoyant rise of the radio lobes through the ambient medium
has directed an inflow towards the relic cold core of the group.
Inverse-Compton emission from the radio lobes is detected at a level consistent
with a slight suppression of the magnetic field below the equipartition value.Comment: 11 pages, 10 figures, accepted for publication in MNRA
Barriers to women in the UK construction industry
Purpose – This paper aims to identify the main barriers that lead to the under-representation of women in the UK construction industry. The study, funded by ConstructionSkills, seeks to explore the issues that women face and investigate the potential positive impact that continuous professional development (CPD) may have upon improving the retention and career progression of women.
Design/methodology/approach – The study uses an open-ended grounded theory (GT) approach, including 231 semi-structured questionnaires and nine focus groups with women from a range of professional occupations. All the findings were analysed using keyword analysis to identify the top two barriers that women face, alongside a series of cross-cutting key themes and issues.
Findings – The findings reveal that male-dominated organisational cultures and inflexible working practices are the main barriers to women in the UK construction industry, irrespective of job role or profession. This paper concludes by arguing for a sea-change in the expansion of CPD opportunities for women in managerial, confidence and communication based skills, with accompanying networking and support systems to facilitate the retention and advancement of women in the industry sector.
Research limitations/implications – Due to the research approach, the data are not generalisable. Therefore, researchers are advised to research and test the findings with a larger group. Researchers are also recommended to investigate the impact of expanded CPD opportunities for both men and women.
Originality/value – The paper puts forward a business case for the advancement of specific CPD training for women, to facilitate the expansion of equality and diversity in the workforce in the UK construction industry
Laser photolysis of photographic image dyes
Studies have been carried out investigating the
photochemical and photophysical properties of pyrazolotriazole
azomethine dyes. Such compounds can be used as
magenta images in the subtractive colour photographic
process. This work has been carried out both in dilute
fluid solution and in high concentration, high viscosity
systems designed to mimic the photographic product.
Picosecond pump-probe laser flash photolysis studies
have provided the first observation of photoinduced
transient absorption changes attributable to the excited
states of this class of dyes, and have allowed assignment
of the excited singlet state lifetime as being in the range
1 to 3ps at room temperature, with little dependence upon
solvent properties or the pattern of substituents on the
dye skeleton. Using picosecond laser flash photolysis it
has also been possible to observe evolution of the population
along the ground state potential surface to the two isomeric
forms, the rate of this process showing some solvent
dependence.
Nanosecond and picosecond laser flash photolysis studies
have been used to investigate the process of syn-anti and
anti-syn isomerisation about the azomethine linkage. The
syn-anti photoisomerisation occurs on picosecond timescales,
the anti isomer so produced relaxing thermally back
to the syn form on timescales ranging from microseconds to
milliseconds. The rate constant for this process is a complex
function of solvent properties as well as being dependent
upon steric factors within the molecule, and the reasons
for this are discussed. Triplet energy sensitisation studies
have demonstrated that a pathway exists for this isomerisation
process via the triplet manifold, and has allowed
determination of minimum isomerisation quantum yields from
the triplet state. Such studies have also allowed estimation
of limits for the molar decadic absorption coefficients of
the anti isomer.
The photographic product dyes have been demonstrated
to be efficient quenchers of singlet molecular oxygen, the
quenching mechanism being predominantly physical in nature.
The quantum yields of singlet oxygen production are too
small to be measured using time resolved techniques. These
factors are used to explain in part the resistance of such
compounds to oxidative photodegradation.
Steady state irradiation of azomethine dyes in systems
designed to simulate the photographic product by a high
intensity source of known spectral profile has allowed
determination of the quantum yields of photodegradation,
which in combination with the results obtained in fluid
solution provide a basis for explaining the behaviour of
image dyes in the photographic product environment
Multifrequency Study of The Radio Galaxy NGC326
We present the results of a multi-frequency study of the inversion symmetric
radio galaxy NGC326 based on Very Large Array observations at 1.4, 1.6, 4.8,
8.5 and 14.9 GHz. The morphological, spectral and polarization properties of
this peculiar object are studied at different levels of spatial resolutions.
The interpretation of the data will be discussed in forthcoming papers.Comment: 15 pages, 15 ps figures, accepted by A&
The inner jet of radio galaxy NGC 315 as observed with Chandra and the VLA
We present Chandra X-ray results for the jet, nucleus, and gaseous atmosphere
of NGC 315, a nearby radio galaxy whose jet kinematics are known through deep
radio mapping. Diffuse X-ray synchrotron emission is detected from the jet out
to 30 arcsec from the nucleus, through regions both of fast bulk flow and
deceleration. The X-ray to radio flux ratio drops considerably where the flow
decelerates, but the X-ray and radio emissions show similar transverse extents
throughout, requiring distributed particle acceleration to maintain the supply
of X-ray-emitting electrons. A remarkable knotty filament within the jet is
seen in both the radio and X-ray, contributing roughly 10 per cent of the
diffuse emission along its extent at both wavelengths. No completely
satisfactory explanation for the filament is found, though its oscillatory
appearance, roughly aligned magnetic field, and requirements for particle
acceleration, suggest that it is a magnetic strand within a shear layer between
fast inner and slower outer flow.Comment: Accepted for publication in the MNRAS. 13 pages,14 figures (some in
colour
The magnetized medium around the radio galaxy B2 0755+37: an interaction with the intra-group gas
We explore the magneto-ionic environment of the isolated radio galaxy B2
0755+37 using detailed imaging of the distributions of Faraday rotation and
depolarization over the radio source from Very Large Array observations at
1385,1465 and 4860 MHz and new X-ray data from XMM-Newton. The Rotation Measure
(RM) distribution is complex, with evidence for anisotropic fluctuations in two
regions. The approaching lobe shows low and uniform RM in an unusual `stripe'
along an extension of the jet axis and a linear gradient transverse to this
axis over its Northern half. The leading edge of the receding lobe shows
arc-like RM structures with sign reversals. Elsewhere, the RM structures are
reasonably isotropic. The RM power spectra are well described by cut-off power
laws with slopes ranging from 2.1 to 3.2 in different sub-regions. The
corresponding magnetic-field autocorrelation lengths, where well-determined,
range from 0.25 to 1.4 kpc. It is likely that the fluctuations are mostly
produced by compressed gas and field around the leading edges of the lobes. We
identify areas of high depolarization around the jets and inner lobes. These
could be produced by dense gas immediately surrounding the radio emission
containing a magnetic field which is tangled on small scales. We also identify
four ways in which the well known depolarization (Faraday depth) asymmetry
between jetted and counter-jetted lobes of extended radio sources can be
modified by interactions with the surrounding medium.Comment: 16 pages, 13 figures, accepted for publication in MNRAS. Full
resolution paper available at: ftp://ftp.ira.inaf.it/pub/outgoing/guidetti/
Subjects: Cosmology and Extragalactic Astrophysics (astro-ph.CO
The X-ray spectrum of 3C 273
An X-ray spectral measurement of the quasar 3C 273 with the HEAO-A2 experiment in June/July 1978 is reported. The best power law fit to the photon flux over the range 2-60 keV gives a slope of 1.41 + or - 0.02. However, structure is observed, indicating a slope of 1.52 between 2 keV and 9 keV and a slight flattening between 9 keV and 30 keV. Observations with the same experiment in December 1977 and OSO-8 in June 1976 allows confirmation of 40% intensity variability on the time scale of months, although within limits provided by the poorer statistical quality of the additional data no spectral change is discerned. Absorption from the source is found to be low, with the 1978 data yielding a 90% confidence upper limit to the hydrogen column density of 4.5 x 10 to the 21st power atoms/sq cm
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