Levitated Spinning Graphene

A method is described for levitating micron-sized few layer graphene flakes in a quadrupole ion trap. Starting from a liquid suspension containing graphene, charged flakes are injected into the trap using the electrospray ionization technique and are probed optically. At micro-torr pressures, torques from circularly polarized light cause the levitated particles to rotate at frequencies >1 MHz, which can be inferred from modulation of light scattering off the rotating flake when an electric field resonant with the rotation rate is applied. Possible applications of these techniques will be presented, both to fundamental measurements of the mechanical and electronic properties of graphene and to new approaches to graphene crystal growth, modification and manipulation.Comment: 23 pages, 11 figure

The slot car stig: Performance and consistency of a slot car driven by a heuristic algorithm in an embedded microcontroller

We present theory and measured performance of an autonomous slot car driven by a heuristic algorithm on a typical track. The hardware consists of a PIC 8-bit single-chip microcontroller with various sensors driving a standard permanent-magnet (PM) brushed dc (BDC) motor in a mechanically-standard Scalextric platform. We present some interesting results concerning the relative difficulty of apparently-balanced lanes on a track. The car achieves optimum lap times with high consistency. Measured performance agrees with theoretical expectation. The consistency of performance allows the impact of experimental changes to be reliably assessed

SuperWASP observations of pulsating Am stars

We have studied over 1600 Am stars at a photometric precision of 1 mmag with SuperWASP photometric data. Contrary to previous belief, we find that around 200 Am stars are pulsating δ Sct and γ Dor stars, with low amplitudes that have been missed in previous, less extensive studies. While the amplitudes are generally low, the presence of pulsation in Am stars places a strong constraint on atmospheric convection, and may require the pulsation to be laminar. While some pulsating Am stars have been previously found to be δ Sct stars, the vast majority of Am stars known to pulsate are presented in this paper. They will form the basis of future statistical studies of pulsation in the presence of atomic diffusion

An exploration of the experience of birth mothers who relinquished a child for adoption between 1960 and 1990 and who subsequently initiated contact with the relinquished child: the clinical implications for practitioners

This is a phenomenological study exploring the experiences of seven birth mothers who relinquished a child for adoption between 1960 and 1990. The aim of the study is to understand the depth and breadth of the experience of relinquishment and to establish whether the impact of relinquishment is long-term. This study explores the relationship between the moral values and social policies that existed during the era of the study and how these factors influenced the birth mothers’ decision-making. The objective of the study is to use the findings to develop therapeutic guidance for practitioners working with birth mothers who have lost a child through adoption. The data was gathered through semi-structured interviews and was analysed using Interpretative Phenomenological Analysis. The women provided compelling accounts of lives consisting of secrecy, shame and loss, harsh treatment by family and professionals, and an absence of any emotional support. Additionally, most of their stories had not been heard before. Three master themes emerged from the findings: 1) The power of social stigmatisation; 2) The unique experience of relinquishment; 3) Experiencing psychological distress. The study shows that the impact of the experience of relinquishment is indeed long term, with a diminishing of the intensity of emotions over time. The lack of acknowledgement of the experience was a significant contributory factor in the longevity of the impact. Clinical implications and recommendations for practitioners who support birth mothers in Adoption Support Agencies are presented. It is anticipated that the recommendations will also be useful for practitioners currently supporting birth mothers whose children have been, or are presently being, taken into care and subsequently adopted. Many of the themes identified in this study, such as loss and stigmatisation, have been shown in the literature to be also present for this group. The findings and clinical implications would therefore have some relevance in supporting these birth mothers

Motion of a symmetric rigid body under the action of a body-fixed force

Approximative method for predicting motion of symmetric rigid body subjected to body-fixed forc

Detection of a single-charge defect in a metal-oxide-semiconductor structure using vertically coupled Al and Si single-electron transistors

An Al-AlO_x-Al single-electron transistor (SET) acting as the gate of a narrow (~ 100 nm) metal-oxide-semiconductor field-effect transistor (MOSFET) can induce a vertically aligned Si SET at the Si/SiO_2 interface near the MOSFET channel conductance threshold. By using such a vertically coupled Al and Si SET system, we have detected a single-charge defect which is tunnel-coupled to the Si SET. By solving a simple electrostatic model, the fractions of each coupling capacitance associated with the defect are extracted. The results reveal that the defect is not a large puddle or metal island, but its size is rather small, corresponding to a sphere with a radius less than 1 nm. The small size of the defect suggests it is most likely a single-charge trap at the Si/SiO_2 interface. Based on the ratios of the coupling capacitances, the interface trap is estimated to be about 20 nm away from the Si SET.Comment: 5 pages and 5 figure

Comparison of storm-time changes of geomagnetic field at ground and at MAGSAT altitudes

Computations concerning variations of the geomagnetic field at MAGSAT altitudes were investigated. Using MAGSAT data for the X, Y, and Z components of the geomagnetic field, a computer conversion to yield the H component was performed. Two methods of determining delta H normalized to a constant geocentric distance R sub 0 = 6800 were investigated, and the utility of elta H at times of magnetic storms was considered. Delta H at a geographical latitude of 0 at dawn and dusk, the standard Dst, and K sub p histograms were plotted and compared. Magnetic anomalies are considered. Examination of data from the majority of the 400 passes of MAGSAT considered show a reasonable delta H versus latitude variation. Discrepancies in values are discussed