Pre-terrestrial oxidation products in carbonaceous meteorites identified by Mossbauer spectroscopy

The occurrence of ferric bearing assemblages, comprising phyllosilicates, oxide hydroxides and magnetite, in carbonaceous chondrites (CC) indicates that these meteorites underwent pre-terrestrial, sub-aqueous oxidation reactions. Reported here are results of a Mossbauer spectral study of a suite of CC demonstrating that a variety of ferrous and ferric bearing phases may be distinguished in different classes of this meteorite type

Evaluation of 3D Printed Immobilisation Shells for Head and Neck IMRT

This paper presents the preclinical evaluation of a novel immobilization system for patients undergoing external beam radiation treatment of head and neck tumors. An immobilization mask is manufactured directly from a 3-D model, built using the CT data routinely acquired for treatment planning so there is no need to take plaster of Paris moulds. Research suggests that many patients find the mould room visit distressing and so rapid prototyping could potentially improve the overall patient experience. Evaluation of a computer model of the immobilization system using an anthropomorphic phantom shows that >99% of vertices are within a tolerance of ±0.2 mm. Hausdorff distance was used to analyze CT slices obtained by rescanning the phantom with a printed mask in position. These results show that for >80% of the slices the median “worse-case” tolerance is approximately 4 mm. These measurements suggest that printed masks can achieve similar levels of immobilization to those of systems currently in clinical use

“Viewed with suspicion, considered idle and mocked-working caregiving fathers and fatherhood forfeits”

Existing academic literature consistently points to a changing role for modern fathers in which they take an egalitarian role in the caregiving responsibilities for their children. Despite this, fathers are observed to continue to dominate the realms of full-time working, aligning to more traditional breadwinning mentalities than such trends might suggest, raising questions around inequality. Fathers at work have previously been found to encounter challenges within the workplace when they alter, or consider altering their work patterns due to caregiving responsibilities. Employing a sample of working parents and managers, this paper explores how caregiving fathers are perceived within organizations and in considering their experiences, provides a nuanced and detailed understanding of the ways in which mistreatment for caregiving fathers manifests within contemporary UK workplaces. Caregiving fathers are found to face specific challenges termed “fatherhood forfeits” such as perceived idleness, suffering mockery, and being viewed with suspicion by male and female co-workers. Actions are proposed to address “fatherhood forfeits” that include specific organizational training interventions and the importance of workplace role modeling

Analysis of prevalence of HIV-1 drug resistance in primary infections in the United Kingdom

Objectives: To identify changes since 1994 in the prevalence of resistance to anti-HIV drugs in primary HIV-1 infections in the United Kingdom. Design: Retrospective and prospective assessment of viruses obtained from people recently infected with HIV. Setting: Multiple centres (patients enrolled in the UK register of seroconverters) and a single large HIV clinic (active case ascertainment). Participants: 69 patients infected with HIV between June 1994 and August 2000. Main outcome measures: Prevalence of key mutations associated with drug resistance in the reverse transcriptase and protease genes of HIV-1, by year of infection. Results: Between June 1994 and August 2000, 10 (14%) of 69 newly infected patients had one or more key HIV-1 mutations associated with drug resistance. The risk of being infected with drug resistant virus increased over time (adjusted relative risk per year 1.74 (95% confidence interval 0.93 to 3.27), P=0.06). The estimated prevalence of drug resistance in those infected in 2000 was 27% (12% to 48%). Conclusions: Transmission of drug resistant HIV-1 in the United Kingdom seems to be increasing. New approaches to encourage safer sexual behaviour in all sectors of the population are urgently needed. What is already known on this topic: The emergence of HIV drug resistance in patients receiving antiretroviral therapy is common. Transmission of virus variants resistant to anti-HIV drugs has been documented. What this paper adds: The prevalence of transmitted HIV drug resistance in the United Kingdom is increasing, exceeding 20% in 2000. New approaches to encourage safer sexual behaviour are urgently needed

Can we constrain structure growth from galaxy proper motions?

Galaxy peculiar velocities can be used to trace the growth of structure on cosmological scales. In the radial direction, peculiar velocities cause redshift space distortions, an established cosmological probe, and can be measured individually in the presence of an independent distance indicator. In the transverse direction, peculiar velocities cause proper motions. In this case, however, the proper motions are too small to detect on a galaxy-by-galaxy basis for any realistic experiment in the foreseeable future, but could be detected statistically in cross-correlation with other tracers of the density fluctuations. We forecast the sensitivity for a detection of transverse peculiar velocities through the cross-correlation of a proper motion survey, modelled after existing extragalactic samples measured by Gaia, and an overlaping galaxy survey. In particular, we consider a low-redshift galaxy sample, and a higher-redshift quasar sample. We find that, while the expected cosmological signal is below the expected statistical uncertainties from current data using cross-correlations, the sensitivity can improve fast with future experiments, and the threshold for detection may not be too far away in the future. Quantitatively, we find that the signal-to-noise ratio for detection is in the range , with most of the signal concentrated at low redshifts . If detected, this signal is sensitive to the product of the expansion and growth rates at late times, and thus would constitute an independent observable, sensitive to both background expansion and large-scale density fluctuations

Quantum optical signal processing in diamond

Controlling the properties of single photons is essential for a wide array of emerging optical quantum technologies spanning quantum sensing, quantum computing, and quantum communications. Essential components for these technologies include single photon sources, quantum memories, waveguides, and detectors. The ideal spectral operating parameters (wavelength and bandwidth) of these components are rarely similar; thus, frequency conversion and spectral control are key enabling steps for component hybridization. Here we perform signal processing of single photons by coherently manipulating their spectra via a modified quantum memory. We store 723.5 nm photons, with 4.1 nm bandwidth, in a room-temperature diamond crystal; upon retrieval we demonstrate centre frequency tunability over 4.2 times the input bandwidth, and bandwidth modulation between 0.5 to 1.9 times the input bandwidth. Our results demonstrate the potential for diamond, and Raman memories in general, to be an integrated platform for photon storage and spectral conversion.Comment: 6 pages, 4 figure

Chemical weathering of sulfide mineralization on Mars

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1990.Includes bibliographical references (leaves 68-76).by Duncan Southam Fisher.M.S

Storage and retrieval of ultrafast single photons using a room-temperature diamond quantum memory

We report the storage and retrieval of single photons, via a quantum memory, in the optical phonons of room-temperature bulk diamond. The THz-bandwidth heralded photons are generated by spontaneous parametric downconversion and mapped to phonons via a Raman transition, stored for a variable delay, and released on demand. The second-order correlation of the memory output is $g^{(2)}(0) = 0.65 \pm 0.07$, demonstrating preservation of non-classical photon statistics throughout storage and retrieval. The memory is low-noise, high-speed and broadly tunable; it therefore promises to be a versatile light-matter interface for local quantum processing applications.Comment: 6 pages, 4 figure