Tool for use in lifting pin supported objects

A tool for use in lifting a pin-supported, electronic package mounted in juxtaposition with the surface of an electronic circuit board is described. The tool is configured to be received beneath a pin-supported package and is characterized by a manually operable linkage, including an elongated, rigid link is supported for axial reciprocation and a pivotal link pinned to the body and supported for oscillation induced in response to axial motion imparted to the rigid link. A lifting plate is pivotally coupled to the distal end of the pivotal link so that oscillatory motion imparted to the pivotal link serves to move the plate vertically for elevating the plate into lifting engagement with the electronic package positioned thereabove

The XMM-Newton slew survey in the 2-10 keV band

The XMM-Newton Slew Survey (XSS) covers a significant fraction of the sky in a broad X-ray bandpass. Although shallow by contemporary standards, in the `classical' 2-10 keV band of X-ray astronomy, the XSS provides significantly better sensitivity than any currently available all-sky survey. We investigate the source content of the XSS, focussing on detections in the 2-10 keV band down to a very low threshold (> 4 counts net of background). At the faint end, the survey reaches a flux sensitivity of roughly 3e-12 erg/cm2/s (2-10 keV). Our starting point was a sample of 487 sources detected in the XMMSL1d2 XSS at high galactic latitude in the hard band. Through cross-correlation with published source catalogues from surveys spanning the electromagnetic spectrum from radio to gamma-rays, we find that 45% of the sources have likely identifications with normal/active galaxies, 18% are associated with other classes of X-ray object (nearby coronally active stars, accreting binaries, clusters of galaxies), leaving 37% of the XSS sources with no current identification. We go on to define an XSS extragalactic hard band sample comprised of 219 galaxies and active galaxies. We investigate the properties of this extragalactic sample including its X-ray logN-logS distribution. We find that in the low-count limit, the XSS is strongly affected by Eddington bias. There is also a very strong bias in the XSS against the detection of extended sources, most notably clusters of galaxies. A significant fraction of the detections at and around the low-count limit may be spurious. Nevertheless, it is possible to use the XSS to extract a reasonably robust sample of extragalactic sources, excluding galaxy clusters. The differential logN-logS relation of these extragalactic sources matches very well to the HEAO-1 A2 all-sky survey measurements at bright fluxes and to the 2XMM source counts at the faint end.Comment: 16 pages, 13 figures, FITS table of XSS extragalactic sample available from http://www.star.le.ac.uk/~amr30/Slew

Ground State Entropy of the Potts Antiferromagnet on Cyclic Strip Graphs

We present exact calculations of the zero-temperature partition function (chromatic polynomial) and the (exponent of the) ground-state entropy $S_0$ for the $q$-state Potts antiferromagnet on families of cyclic and twisted cyclic (M\"obius) strip graphs composed of $p$-sided polygons. Our results suggest a general rule concerning the maximal region in the complex $q$ plane to which one can analytically continue from the physical interval where $S_0 > 0$. The chromatic zeros and their accumulation set ${\cal B}$ exhibit the rather unusual property of including support for $Re(q) < 0$ and provide further evidence for a relevant conjecture.Comment: 7 pages, Latex, 4 figs., J. Phys. A Lett., in pres

A spatial accuracy assessment of an alternative circular scan method for Kulldorff's spatial scan statistic

This paper concerns the Bernoulli version of Kulldorff’s spatial scan statistic, and how accurately it identifies the exact centre of approximately circular regions of increased spatial density in point data. We present an alternative method of selecting circular regions that appears to give greater accuracy. Performance is tested in an epidemiological context using manifold synthetic case-control datasets. A small, but statistically significant, improvement is reported. The power of the alternative method is yet to be assessed

A pilot inference study for a beta-Bernoulli spatial scan statistic

The Bernoulli spatial scan statistic is used to detect localised clusters in binary labelled point data, such as that used in spatial or spatio-temporal case/control studies. We test the inferential capability of a recently developed beta-Bernoulli spatial scan statistic, which adds a beta prior to the original statistic. This pilot study, which includes two test scenarios with 6,000 data sets each, suggests a marked increase in power for a given false alert rate. We suggest a more extensive study would be worthwhile to corroborate the findings. We also speculate on an explanation for the observed improvement

A Power-Enhanced Algorithm for Spatial Anomaly Detection in Binary Labelled Point Data Using the Spatial Scan Statistic [postprint]

This paper presents a novel modification to an existing algorithm for spatial anomaly detection in binary labeled point data sets, using the Bernoulli version of the Spatial Scan Statistic. We identify a potential ambiguity in p-values produced by Monte Carlo testing, which (by the selection of the most conservative p-value) can lead to sub-optimal power. When such ambiguity occurs, the modification uses a very inexpensive secondary test to suggest a less conservative p-value. Using benchmark tests, we show that this appears to restore power to the expected level, whilst having similarly retest variance to the original. The modification also appears to produce a small but significant improvement in overall detection performance when multiple anomalies are present

Assessing atmospheric predictability on Mars using numerical weather prediction and data assimilation

Introduction: Studies of the time series of surface measurements of wind, pressure and temperature at the two Viking landers by Barnes [1], [2] revealed that baroclinic transient travelling waves on Mars occur mostly during northern hemisphere autumn, winter and early spring, and typically take the form of highly coherent patterns with planetary wavenumbers 1-3 that can persist for intervals of up to 30-60 sols before changing erratically. Such behaviour is almost unknown on Earth, where individual baroclinic weather systems typically persist for no longer than 5-10 days and seldom remain coherent around entire latitude circles. This occurrence of planetary-scale coherent baroclinic wave-like weather systems on Mars led to suggestions [3] that Mars' atmospheric circulation operates in a quite different dynamical regime to that of the Earth, one that tends to favour regular, symmetrical baroclinic wave activity in a manner reminiscent of the regular wave regimes found in laboratory fluid dynamics experiments on sloping convection in a rotating, thermally-driven fluid annulus (e.g. [4], [5]). In its extreme form, this hypothetical comparison would suggest the possibility of a fully non-chaotic atmospheric circulation on Mars, though subsequent modelling work [6] indicated that perturbations due to the thermal tide would lead to chaotic transitions back and forth between different intransitive wave states. This form of (relatively low-dimensional) chaotic modeflipping appeared to be consistent with the Viking observations of Mars, suggesting nevertheless that the intrinsic predictability of Mars' mid-latitude meteorology was qualitatively and quantitatively quite different from that of the Earth

The XMM-Newton Slew Survey: Towards The Whole X-ray Sky and the Rarest X-ray Events

The data collected by XMM-Newton as it slews between pointings currently cover almost half the entire sky, and many familiar features and new sources are visible. The soft-band sensitivity limit of the Slew is close to that of the RASS, and a large-area Slew-RASS comparison now provides the best opportunity for discovering extremely rare high-variability objects.Comment: To appear in Proceedings of "X-ray Astronomy 2009: Present Status, Multi-Wavelength Approach and Future Perspectives", Bologna, Italy, September 7-11, 2009, AIP, eds. A. Comastri, M. Cappi, and L. Angelin

Ground State Entropy of Potts Antiferromagnets on Cyclic Polygon Chain Graphs

We present exact calculations of chromatic polynomials for families of cyclic graphs consisting of linked polygons, where the polygons may be adjacent or separated by a given number of bonds. From these we calculate the (exponential of the) ground state entropy, $W$, for the q-state Potts model on these graphs in the limit of infinitely many vertices. A number of properties are proved concerning the continuous locus, ${\cal B}$, of nonanalyticities in $W$. Our results provide further evidence for a general rule concerning the maximal region in the complex q plane to which one can analytically continue from the physical interval where $S_0 > 0$.Comment: 27 pages, Latex, 17 figs. J. Phys. A, in pres