The time cost of care

Extensive small scale studies have documented that when people assume the role of assisting a person with impairments or an older person, care activities account for a significant portion of their daily routines. Nevertheless, little research has investigated the problem of measuring the time that carers spend in care-related activities. This paper contrasts two different measures of care time – an estimated average weekly hours question in the 1998 Australian Survey of Disability, Ageing and Carers, and diary estimates from the 1997 national Australian Time Use Survey. This study finds that diaries provide information for a more robust estimate, but only after one models the time use patterns in the days of carers to identify care-related activities, which diarists do not necessarily record as care. Such a measure of care time reveals that even people who offer only occasional assistance to a person with impairments tend to spend the equivalent of more than 10 minutes a day providing care. Most caregivers undertake the equivalent of a part-time job to help a friend or family member. Summing the average caregiving time provided by all household members reveals that over a quarter of Australian households caring for an adult or child provide the equivalent of a full-time employee’s labour, and another quarter work between 20 and 39 total weekly hours to provide informal care.Care, unpaid work, time estimation, family and gender roles, informal economic activity

Young Workers, Old Workers, and Convergence

The human capital of young and old workers are imperfect substitutes both in production and in on-the-job training. This helps explain why capital does not flow from rich to poor countries, causing instantaneous convergence of per capita output. If each generation chooses its human capital optimally given that of the previous and succeeding generations, human capital follows a unique rational- expectations path. For moderate substitutability, human capital within each sector oscillates relative to that in other sectors, but aggregate human capital converges to the steady state monotonically, at rates consistent with those observed empirically.

Ultrafast dynamic conductivity and scattering rate saturation of photoexcited charge carriers in silicon investigated with a midinfrared continuum probe

We employ ultra-broadband terahertz-midinfrared probe pulses to characterize the optical response of photoinduced charge-carrier plasmas in high-resistivity silicon in a reflection geometry, over a wide range of excitation densities (10^{15}-10^{19} cm^{-3}) at room temperature. In contrast to conventional terahertz spectroscopy studies, this enables one to directly cover the frequency range encompassing the resultant plasma frequencies. The intensity reflection spectra of the thermalized plasma, measured using sum-frequency (up-conversion) detection of the probe pulses, can be modeled well by a standard Drude model with a density-dependent momentum scattering time of approx. 200 fs at low densities, reaching approx. 20 fs for densities of approx. 10^{19} cm^{-3}, where the increase of the scattering rate saturates. This behavior can be reproduced well with theoretical results based on the generalized Drude approach for the electron-hole scattering rate, where the saturation occurs due to phase-space restrictions as the plasma becomes degenerate. We also study the initial sub-picosecond temporal development of the Drude response, and discuss the observed rise in the scattering time in terms of initial charge-carrier relaxation, as well as the optical response of the photoexcited sample as predicted by finite-difference time-domain simulations.Comment: 9 pages, 4 figure

Simulated holographic three-dimensional intensity shaping of evanescent-wave fields

The size of bright structures in traveling-wave light fields is limited by diffraction. This in turn limits a number of technologies, for example, optical trapping. One way to beat the diffraction limit is to use evanescent waves instead of traveling waves. Here we apply a holographic algorithm, direct search, to the shaping of complex evanescent-wave fields. We simulate three-dimensional intensity shaping of evanescent-wave fields using this approach, and we investigate some of its limitations. (c) 2008 Optical Society of America.</p

Experience with Ada on the F-18 High Alpha Research Vehicle Flight Test Program

Considerable experience was acquired with Ada at the NASA Dryden Flight Research Facility during the on-going High Alpha Technology Program. In this program, an F-18 aircraft was highly modified by the addition of thrust-vectoring vanes to the airframe. In addition, substantial alteration was made in the original quadruplex flight control system. The result is the High Alpha Research Vehicle. An additional research flight control computer was incorporated in each of the four channels. Software for the research flight control computer was written in Ada. To date, six releases of this software have been flown. This paper provides a detailed description of the modifications to the research flight control system. Efficient ground-testing of the software was accomplished by using simulations that used the Ada for portions of their software. These simulations are also described. Modifying and transferring the Ada for flight software to the software simulation configuration has allowed evaluation of this language. This paper also discusses such significant issues in using Ada as portability, modifiability, and testability as well as documentation requirements

Simulation of position sensitivity of the anomalous Hall effect on a single magnetic dot

To overcome the superparamagnetic effect caused by scaling bit and grain sizes in magnetic storage media different approaches are investigated. One alternative is bit patterned magnetic media (BPM) where each bit is represented by a single domain magnetic dot. A key problem with BPM is the large difference in magnetic field necessary to switch the magnetization direction of the various dot which is characterized by the switching field distribution

Co dimers on hexagonal carbon rings proposed as subnanometer magnetic storage bits

It is demonstrated by means of density functional and ab-initio quantum chemical calculations, that transition metal - carbon systems have the potential to enhance the presently achievable area density of magnetic recording by three orders of magnitude. As a model system, Co_2-benzene with a diameter of 0.5 nm is investigated. It shows a magnetic anisotropy in the order of 0.1 eV per molecule, large enough to store permanently one bit of information at temperatures considerably larger than 4 K. A similar performance can be expected, if cobalt dimers are deposited on graphene or on graphite. It is suggested that the subnanometer bits can be written by simultaneous application of a moderate magnetic and a strong electric field.Comment: 13 pages, 4 figure

Reconsidering the rise in A-level mathematics participation

There is growing support for making the study of mathematics to age 18 compulsory for all young people in England. This paper aims to inform this debate through new insights into historic A-level Mathematics participation trends. We analyse full-year cohorts from the Department for Education’s National Pupil Database for age-16 students from 2004-2010, a total of just over 4.5 million young people. Using a cohort-tracking approach we aim to better understand the flow of young people through upper secondary mathematics education. Earlier work identified GCSE attainment as the strongest predictor of A-Level Mathematics participation. In this paper we show that the percentage of students progressing to A-Level by GCSE grade has not changed significantly over the period in question, with some exceptions. This implies that the increase in A-level Mathematics numbers is largely explained by the growing proportion of higher GCSE grades. We discuss the implications for policy that this raises, e.g. the possible impact of making GCSE mathematics more demanding