Interact with Speciknee: A Software Tool for Design of Simple Four-bar Prosthesic Knee Joints

This poster and interactive demonstration presents an educational computer design tool which could enable prosthetists and mechanical designers to tailor the motion of low-cost, four-bar prosthetic knees to the sizes and needs of individual amputees. In designing a prosthetic knee joint, it is important to control the position of the lower leg in three angles of flexion and to control its center of rotation in the standing position. In 2010 [1] this problem was analyzed using vector methods, and an algorithm was written which produced curves displaying pivot locations which solve the problem exactly. Since then, a software tool called Speciknee has been developed by building on the core vector computational method and adding a user-friendly operator interface through which a designer could input individual patient needs, select pivot points along the set of curves where prosthetic joint pivots could be placed, and animate the mechanism. [1] Thompson, Thomas J., 2010, Specification of Prosthetic Knee Kinematic Design Parameters Using a Three-position, Instant-center Specification Approach, paper No. IMECE2010-38645, Proceedings of the ASME International Mechanical Engineering Congress and Exposition, Vancouver, British Columbia, Canada, November

Extreme asteroids in the Pan-STARRS 1 Survey

Using the first 18 months of the Pan-STARRS 1 survey we have identified 33 candidate high-amplitude objects for follow-up observations and carried out observations of 22 asteroids. 4 of the observed objects were found to have observed amplitude $A_{obs}\geq 1.0$ mag. We find that these high amplitude objects are most simply explained by single rubble pile objects with some density-dependent internal strength, allowing them to resist mass shedding even at their highly elongated shapes. 3 further objects although below the cut-off for 'high-amplitude' had a combination of elongation and rotation period which also may require internal cohesive strength, depending on the density of the body. We find that none of the 'high-amplitude asteroids' identified here require any unusual cohesive strengths to resist rotational fission. 3 asteroids were sufficiently observed to allow for shape and spin pole models to be determined through light curve inversion. 45864 was determined to have retrograde rotation with spin pole axes $\lambda=218\pm 10^{\circ}, \beta=-82\pm 5^{\circ}$ and asteroid 206167 was found to have best fit spin pole axes $\lambda= 57 \pm 5^{\circ}$, $\beta=-67 \pm 5^{\circ}$. An additional object not initially measured with $A_{obs}>1.0$ mag, 49257, was determined to have a shape model which does suggest a high-amplitude object. Its spin pole axes were best fit for values $\lambda=112\pm 6^{\circ}, \beta=6\pm 5^{\circ}$. In the course of this project to date no large super-fast rotators ($P_{rot} < 2.2$ h) have been identified.Comment: 31 pages; accepted by A

GaN directional couplers for integrated quantum photonics

Large cross-section GaN waveguides are proposed as a suitable architecture to achieve integrated quantum photonic circuits. Directional couplers with this geometry have been designed with aid of the beam propagation method and fabricated using inductively coupled plasma etching. Scanning electron microscopy inspection shows high quality facets for end coupling and a well defined gap between rib pairs in the coupling region. Optical characterization at 800 nm shows single-mode operation and coupling-length-dependent splitting ratios. Two photon interference of degenerate photon pairs has been observed in the directional coupler by measurement of the Hong-Ou-Mandel dip with 96% visibility.Comment: 4 pages, 5 figure

The Changing Face of α Centauri B: Probing plage and stellar activity in K-dwarfs

A detailed knowledge of stellar activity is crucial for understanding stellar dynamos, as well as pushing exoplanet radial-velocity detection limits towards Earth analogue confirmation. We directly compare archival HARPS spectra taken at the minimum in $\alpha$ Cen B's activity cycle to a high-activity state when clear rotational modulation of $\log{R'_{HK}}$ is visible. Relative to the inactive spectra, we find a large number of narrow pseudo-emission features in the active spectra with strengths that are rotationally modulated. These features most likely originate from plage, spots, or a combination of both. They also display radial velocity variations of $\sim$300 m s$^{-1}$ - consistent with an active region rotating across the stellar surface. Furthermore, we see evidence that some of the lines originating from the `active immaculate' photosphere appear broader relative to the `inactive immaculate' case. This may be due to enhanced contributions of e.g. magnetic bright points to these lines, which then causes additional line broadening. More detailed analysis may enable measurements of plage and spot coverage using single spectra in the future.Comment: 6 pages, 4 figures, accepted for publication in Monthly Notices of the Royal Astronomical Society (MNRAS) Letter

Risk Prediction Scores for Postoperative Mortality After Esophagectomy: Validation of Different Models

Background: Different prediction models for operative mortality after esophagectomy have been developed. The aim of this study is to independently validate prediction models from Philadelphia, Rotterdam, Munich, and the ASA. Methods: The scores were validated using logistic regression models in two cohorts of patients undergoing esophagectomy for cancer from Switzerland (n = 170) and Australia (n = 176). Results: All scores except ASA were significantly higher in the Australian cohort. There was no significant difference in 30-day mortality or in-hospital death between groups. The Philadelphia and Rotterdam scores had a significant predictive value for 30-day mortality (p = 0.001) and in-hospital death (p = 0.003) in the pooled cohort, but only the Philadelphia score had a significant prediction value for 30-day mortality in both cohorts. Neither score showed any predictive value for in-hospital death in Australians but were highly significant in the Swiss cohort. ASA showed only a significant predictive value for 30-day mortality in the Swiss. For in-hospital death, ASA was a significant predictor in the pooled and Swiss cohorts. The Munich score did not have any significant predictive value whatsoever. Conclusion: None of the scores can be applied generally. A better overall predictive score or specific prediction scores for each country should be develope

Report of the Working Group on `W Mass and QCD' (Phenomenology Workshop on LEP2 Physics, Oxford, April 1997)

The W Mass and QCD Working Group discussed a wide variety of topics relating to present and future measurements of M(W) at LEP2, including QCD backgrounds to W+W- production. Particular attention was focused on experimental issues concerning the direct reconstruction and threshold mass measurements, and on theoretical and experimental issues concerning the four jet final state. This report summarises the main conclusions.Comment: 43 pages LaTeX and 15 encapsulated postscript figures. Uses epsfig and ioplppt macros. Full Proceedings to be published in Journal of Physics

The impact of target frequency on intra-individual variability in euthymic bipolar disorder: a comparison of two sustained attention tasks.

Greater intra-individual variability (IIV) in reaction time (RT) on a sustained attention task has been reported in patients with bipolar disorder (BD) compared with healthy controls. However, it is unclear whether IIV is task specific, or whether it represents general crosstask impairment in BD. This study aimed to investigate whether IIV occurs in sustained attention tasks with different parameters. Twenty-two patients with BD (currently euthymic) and 17 controls completed two sustained attention tasks on different occasions: a low target frequency (~20%) Vigil continuous performance test (CPT) and a high target frequency (~70%) CPT version A-X (CPT-AX). Variability measures (individual standard deviation and coefficient of variation) were calculated per participant, and ex-Gaussian modeling was also applied. This was supplemented by Vincentile analysis to characterize RT distributions. Results indicated that participants (patients and controls) were generally slower and more variable when completing the Vigil CPT compared with CPT-AX. Significant group differences were also observed in the Vigil CPT, with euthymic BD patients being more variable than controls. This result suggests that IIV in BD demonstrates some degree of task specificity. Further research should incorporate analysis of additional RT distributional models (drift diffusion and fast Fourier transform) to fully characterize the pattern of IIV in BD, as well as its relationship to cognitive processes

Probing halo nucleus structure through intermediate energy elastic scattering

This work addresses the question of precisely what features of few body models of halo nuclei are probed by elastic scattering on protons at high centre-of-mass energies. Our treatment is based on a multiple scattering expansion of the proton-projectile transition amplitude in a form which is well adapted to the weakly bound cluster picture of halo nuclei. In the specific case of $^{11}$Li scattering from protons at 800 MeV/u we show that because core recoil effects are significant, scattering crosssections can not, in general, be deduced from knowledge of the total matter density alone. We advocate that the optical potential concept for the scattering of halo nuclei on protons should be avoided and that the multiple scattering series for the full transition amplitude should be used instead.Comment: 8 pages REVTeX, 1 eps figure, accepted for publication in Phys. Rev.

Search for B⁺_c→π⁺μ⁺μ⁻ decays and measurement of the branching fraction ratio <i>B</i>(B⁺_c→ψ(2<i>S</i>)π⁺)/<i>B</i>(B⁺_c→<i>J</i>/ψπ⁺)

The first search for nonresonant B+c→π+μ+μ− decays is reported. The analysis uses proton-proton collision data collected with the LHCb detector between 2011 and 2018, corresponding to an integrated luminosity of 9 fb−1. No evidence for an excess of signal events over background is observed and an upper limit is set on the branching fraction ratio B(B+c→π+μ+μ−)/B(B+c→J/ψπ+)&lt;2.1×10−4 at 90% confidence level. Additionally, an updated measurement of the ratio of the B+c→ψ(2S)π+ and B+c→J/ψπ+ branching fractions is reported. The ratio B(B+c→ψ(2S)π+)/B(B+c→J/ψπ+) is measured to be 0.254±0.018±0.003±0.005, where the first uncertainty is statistical, the second systematic, and the third is due to the uncertainties on the branching fractions of the leptonic J/ψ and ψ(2S) decays. This measurement is the most precise to date and is consistent with previous LHCb results

Evaluation of Affymetrix Gene Chip sensitivity in rat hippocampal tissue using SAGE analysis *

DNA microarrays are a powerful tool for monitoring thousands of transcript levels simultaneously. However, the use of DNA microarrays in studying the central nervous system faces several challenges. These include the detection of low-abundance transcripts in highly complex tissue as well as estimating relatively low-magnitude changes in transcript levels in response to experimental manipulation. Many transcripts important to brain function have low expression levels or are expressed in relatively few cells, making them difficult to detect in the complex background of brain tissue. The aim of the present study is to evaluate the sensitivity of Gene Chip detection of transcripts in brain by using results from serial analysis of gene expression (SAGE) studies. The results of this comparison indicate that Affymetrix Gene Chips, like SAGE, only reliably detect medium- to high-abundance transcripts and that detection of low-abundance transcripts, many of which have great relevance to biological function in brain, is inconsistent. Specifically, we estimate that Gene Chips reliably detect no more than 30% of the hippocampal transcriptome when using a gross hippocampal dissection as the source tissue. This report provides the first broad evaluation of Affymetrix Gene Chip sensitivity relevant to studying the brain.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75717/1/j.1460-9568.2002.02097.x.pd