9,905 research outputs found
Effect of motion frequency spectrum on subjective comfort response
In order to model passenger reaction to present and future aircraft environments, it is necessary to obtain data in several ways. First, of course, is the gathering of environmental and passenger reaction data on commercial aircraft flights. In addition, detailed analyses of particular aspects of human reaction to the environment are best studied in a controllable experimental situation. Thus the use of simulators, both flight and ground based, is suggested. It is shown that there is a reasonably high probability that the low frequency end of the spectrum will not be necessary for simulation purposes. That is, the fidelity of any simulation which omits the very low frequency content will not yield results which differ significantly from the real environment. In addition, there does not appear to be significant differences between the responses obtained in the airborne simulator environment versus those obtained on commercial flights
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One size fits all: How many default funds does a pension scheme need?
In this paper, we analyse the number of default investment funds appropriate for an occupational defined contribution pension scheme. Using a unique dataset of member risk attitudes and characteristics from a survey of a large UK pension scheme, we apply cluster analysis to identify two distinct groups of members in their 40s and 50s. Further analysis indicated that the risk attitudes of the two groups were not significantly different, allowing us to conclude that a single lifestyle default fund is appropriate
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Grouping Individual Investment Preferences in Retirement Savings: A Cluster Analysis of a USS Members Risk Attitude Survey
Cluster analysis is used to identify homogeneous groups of members of USS in terms of risk attitudes. There are two distinct clusters of members in their 40s and 50s. One had previously ‘engaged’ with USS by making additional voluntary contributions. It typically had higher pay, longer tenure, less interest in ethical investing, lower risk capacity, a higher percentage of males, and a higher percentage of academics than members of the ‘disengaged’ cluster. Conditioning only on the attitude to risk responses, there are 18 clusters, with similar but not identical membership, depending on which clustering method is used. The differences in risk aversion across the 18 clusters could be explained largely by differences in the percentage of females and the percentage of couples. Risk aversion increases as the percentage of females in the cluster increases, while it reduces as the percentage of couples increases because of greater risk sharing within the household. Characteristics that other studies have found important determinants of risk attitudes, such as age, income and (pension) wealth, do not turn out to be as significant for USS members. Further, despite being on average more highly educated than the general population, USS members are marginally more risk averse than the general population, controlling for salary, although the difference is not significant
Does selection for growth rate in broilers affect their resistance and tolerance to Eimeria maxima?
ISO LWS Spectra of T Tauri and Herbig AeBe stars
We present an analysis of ISO-LWS spectra of eight T Tauri and Herbig AeBe young stellar objects.
Some of the objects are in the embedded phase of star-formation, whereas others have cleared their environs
but are still surrounded by a circumstellar disk. Fine-structure lines of [OI] and [CII] are most likely excited by
far-ultraviolet photons in the circumstellar environment rather than high-velocity outflows, based on comparisons
of observed line strengths with predictions of photon-dominated and shock chemistry models. A subset of our
stars and their ISO spectra are adequately explained by models constructed by Chiang & Goldreich (1997) and
Chiang et al. (2001) of isolated, passively heated, flared circumstellar disks. For these sources, the bulk of the
LWS flux at wavelengths longward of 55 µm arises from the disk interior which is heated diffusively by reprocessed
radiation from the disk surface. At 45 µm, water ice emission bands appear in spectra of two of the coolest stars,
and are thought to arise from icy grains irradiated by central starlight in optically thin disk surface layers
Field-induced nematic-like magnetic transition in an iron pnictide superconductor, Ca(PtAs)((FePt)As)
We report a high magnetic field study up to 55 T of the nearly optimally
doped iron-pnictide superconductor Ca(PtAs)
((FePt)As) (x=0.078(6)) with a Tc 10 K using
magnetic torque, tunnel diode oscillator technique and transport measurements.
We determine the superconducting phase diagram, revealing an anisotropy of the
irreversibility field up to a factor of 10 near Tc and signatures of multiband
superconductivity. Unexpectedly, we find a spin-flop like anomaly in magnetic
torque at 22 T, when the magnetic field is applied perpendicular to the ab
planes, which becomes significantly more pronounced as the temperature is
lowered to 0.33 K. As our superconducting sample lies well outside the
antiferromagnetic region of the phase diagram, the observed field-induced
transition in torque indicates a spin-flop transition not of long-range ordered
moments, but of nematic-like antiferromagnetic fluctuations.Comment: Latex, 4 figure
Spectroscopic applications and frequency locking of THz photomixing with distributed-Bragg-reflector diode lasers in low-temperature-grown GaAs
A compact, narrow-linewidth, tunable source of THz radiation has been developed for spectroscopy and other high-resolution applications. Distributed-Bragg-reflector (DBR) diode lasers at 850 nm are used to pump a low-temperature-grown GaAs photomixer. Resonant optical feedback is employed to stabilize the center frequencies and narrow the linewidths of the DBR lasers. The heterodyne linewidth full-width at half-maximum of two optically locked DBR lasers is 50 kHz on the 20 ms time scale and 2 MHz over 10 s; free-running DBR lasers have linewidths of 40 and 90 MHz on such time scales. This instrument has been used to obtain rotational spectra of acetonitrile (CH3CN) at 313 GHz. Detection limits of 1 × 10^–4 Hz^1/2 (noise/total power) have been achieved, with the noise floor dominated by the detector's noise equivalent power
Diagonally Neighbour Transitive Codes and Frequency Permutation Arrays
Constant composition codes have been proposed as suitable coding schemes to
solve the narrow band and impulse noise problems associated with powerline
communication. In particular, a certain class of constant composition codes
called frequency permutation arrays have been suggested as ideal, in some
sense, for these purposes. In this paper we characterise a family of neighbour
transitive codes in Hamming graphs in which frequency permutation arrays play a
central rode. We also classify all the permutation codes generated by groups in
this family
Density of states and zero Landau level probed through capacitance of graphene
We report capacitors in which a finite electronic compressibility of graphene
dominates the electrostatics, resulting in pronounced changes in capacitance as
a function of magnetic field and carrier concentration. The capacitance
measurements have allowed us to accurately map the density of states D, and
compare it against theoretical predictions. Landau oscillations in D are robust
and zero Landau level (LL) can easily be seen at room temperature in moderate
fields. The broadening of LLs is strongly affected by charge inhomogeneity that
leads to zero LL being broader than other levels
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