8,782 research outputs found
Material Flow Analysis: Outcome Focus (MFA:OF) for Elucidating the Role of Infrastructure in the Development of a Liveable City
Engineered infrastructures (i.e., utilities, transport & digital) underpin modern society. Delivering services via these
is especially challenging in cities where differing infrastructures form a web of interdependencies. There must be a
step change in how infrastructures deliver services to cities, if those cities are to be liveable in the future (i.e., provide
for citizen wellbeing, produce less CO2 & ensure the security of the resources they use). Material Flow Analysis
(MFA) is a useful methodology for understanding how infrastructures transfer resources to, within and from cities
and contribute to the city’s metabolism. Liveable Cities, a five-year research programme was established to identify
& test radical engineering interventions leading to liveable cities of the future. In this paper, the authors propose an
outcome-focussed variation on the MFA methodology (MFA: OF), evidenced through work on the resource flows of
Birmingham, UK. These flows include water, energy, food & carbon-intensive materials (e.g., steel, paper, glass), as
well as their associated waste. The contribution MFA: OF makes to elucidating the interactions & interdependencies
between the flows is highlighted and suggestions are made for how it can contribute to the (radical) rethinking of the
engineered infrastructure associated with such flow
Cosmological dynamics of Scalar--Tensor Gravity
We study the phase--space of FLRW models derived from Scalar--Tensor Gravity
where the non--minimal coupling is and the effective
potential is . Our analysis allows to unfold many
feature of the cosmology of this class of theories. For example, the evolution
mechanism towards states indistinguishable from GR is recovered and proved to
depend critically on the form of the potential . Also, transient
almost--Friedmann phases evolving towards accelerated expansion and unstable
inflationary phases evolving towards stable ones are found. Some of our results
are shown to hold also for the String-Dilaton action.Comment: 25 pages, 4 figures, 12 tables, submitted to CQ
A polyphonic acoustic vortex and its complementary chords
Using an annular phased array of eight loudspeakers, we generate sound beams that simultaneously contain phase singularities at a number of different frequencies. These frequencies correspond to different musical notes and the singularities can be set to overlap along the beam axis, creating a polyphonic acoustic vortex. Perturbing the drive amplitudes of the speakers means that the singularities no longer overlap, each note being nulled at a slightly different lateral position, where the volume of the other notes is now nonzero. The remaining notes form a tri-note chord. We contrast this acoustic phenomenon to the optical case where the perturbation of a white light vortex leads to a spectral spatial distribution
Violation of Leggett inequalities in orbital angular momentum subspaces
We report an experimental test of Leggett's non-local hidden variable theory in an orbital angular momentum (OAM) state space of light. We show that the correlations we observe are in conflict with Leggett's model, thus excluding a particular class of non-local hidden variable theories for the first time in a non-polarization state space. It is known that the violation of the Leggett inequality becomes stronger as more detection settings are used. The required measurements become feasible in an OAM subspace, and we demonstrate this by testing the inequality using three and four settings. We observe excellent agreement with quantum predictions and a violation of five and six standard deviations, respectively, compared to Leggett's non-local hidden variable theory
The effect of external forces on discrete motion within holographic optical tweezers
Holographic optical tweezers is a widely used technique to manipulate the individual positions of optically trapped micron-sized particles in a sample. The trap positions are changed by updating the holographic image displayed on a spatial light modulator. The updating process takes a finite time, resulting in a temporary decrease of the intensity, and thus the stiffness, of the optical trap. We have investigated this change in trap stiffness during the updating process by studying the motion of an optically trapped particle in a fluid flow. We found a highly nonlinear behavior of the change in trap stiffness vs. changes in step size. For step sizes up to approximately 300 nm the trap stiffness is decreasing. Above 300 nm the change in trap stiffness remains constant for all step sizes up to one particle radius. This information is crucial for optical force measurements using holographic optical tweezers
Organisational responses to students' mental health needs : social, psychological and medical perspectives
This research examines the support offered to students with mental and emotional problems in Oxford, based on a theoretical model which distinguishes between social, psychological and medical/biological approaches. Although there has been a long-running debate about the contribution of each of these approaches, their impact on the provision of formal and informal support for students has not been previously studied.
Using a case study research design, 76 semi-structured interviews were conducted with 'students and staff within three educational institutions and two healthcare trusts, with additional information coming from meetings of the Oxford Student Mental Health Network and other documentary evidence. The case studies found that concerns about
stigma, confidentiality, damaged career prospects and beliefs about the nature of the support provided all impacted on students' willingness to seek help. Sources of social support included friends, family, student officers, academic, residential and administrative staff. Psychological support came from university counsellors and National Health Service
psychotherapists. General Practitioners provided the first line of medical support, with psychiatrists and other mental health professionals becoming involved with the more severe cases. There were gaps between the different levels of support, concerns about the difficulty in accessing secondary and tertiary levels of care, and sometimes mutual
suspicion between different types of supporters.
The distinctions between social, psychological and medical approaches to mental health which tend to be polarised in the literature, were not articulated so forcefully by the majority of the respondents. Integrating different forms of support was seen as providing students with the best chance of completing their studies successfully, but raises challenges
of working across organisational and professional boundaries. Whilst there were established pathways for referring students into psychological and medical services at times of crisis, there were not such well organised pathways back in to the social levels of support upon recovery
Endocrine and fluid metabolism in males and females of different ages after bedrest, acceleration and lower body negative pressure
Space shuttle flight simulations were conducted to determine the effects of weightlessness, lower body negative pressure (LBNP), and acceleration of fluid and electrolyte excretion and the hormones that control it. Measurements were made on male and female subjects of different ages before and after bedrest. After admission to a controlled environment, groups of 6 to 14 subjects in the age ranges 25 to 35, 35 to 45, 45 to 55 to 65 years were exposed to +3 G sub z for 15 minutes (G1) and to LBNP (LBNP1) on different days. On 3 days during this prebedrest period, no tests were conducted. Six days of bedrest followed, and the G sub z (G2) and LBNP (LBNP2) tests were run again. Hormones, electrolytes, and other parameters were measured in 24-hour urine pools throughout the experiment. During bedrest, cortisol and aldosterone excretion increased. Urine volume decreased, and specific gravity and osmolality increased. Urinary electrolytes were statistically unchanged from levels during the non-stress control period. During G2, cortisol increased significantly over its control and bedrest levels. Urine volume, sodium, and chloride were significantly lower; specific gravity and osmolality were higher during the control period or bedrest. The retention of fluids and electrolytes after +G sub z may at least partially explain decreased urine volume and increased osmolality observed during bedrest in this study. There were some who indicated that space flight would not affect the fluid and electrolyte metabolism of females or older males any more severely than it has affected that of male astronauts
Aberration corrections for free-space optical communications in atmosphere turbulence using orbital angular momentum states
Modelling the Galactic Magnetic Field on the Plane in 2D
We present a method for parametric modelling of the physical components of
the Galaxy's magnetised interstellar medium, simulating the observables, and
mapping out the likelihood space using a Markov Chain Monte-Carlo analysis. We
then demonstrate it using total and polarised synchrotron emission data as well
as rotation measures of extragalactic sources. With these three datasets, we
define and study three components of the magnetic field: the large-scale
coherent field, the small-scale isotropic random field, and the ordered field.
In this first paper, we use only data along the Galactic plane and test a
simple 2D logarithmic spiral model for the magnetic field that includes a
compression and a shearing of the random component giving rise to an ordered
component. We demonstrate with simulations that the method can indeed constrain
multiple parameters yielding measures of, for example, the ratios of the
magnetic field components. Though subject to uncertainties in thermal and
cosmic ray electron densities and depending on our particular model
parametrisation, our preliminary analysis shows that the coherent component is
a small fraction of the total magnetic field and that an ordered component
comparable in strength to the isotropic random component is required to explain
the polarisation fraction of synchrotron emission. We outline further work to
extend this type of analysis to study the magnetic spiral arm structure, the
details of the turbulence as well as the 3D structure of the magnetic field.Comment: 18 pages, 11 figures, updated to published MNRAS versio
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