Search

We present continent-scale very-long-baseline interferometry (VLBI) – obtained with the European VLBI Network (EVN) at a wavelength of 18 cm – of six distant, luminous submillimetre-selected galaxies (SMGs). Our images have a synthesized beamwidth of ≈30 mas FWHM – three orders of magnitude smaller in area than the highest resolution Very Large Array (VLA) imaging at this frequency – and are capable of separating radio emission from ultra-compact radio cores (associated with active super-massive black holes – SMBHs) from that due to starburst activity. Despite targeting compact sources – as judged by earlier observations with the VLA and MERLIN – we identify ultra-compact cores in only two of our targets. This suggests that the radio emission from SMGs is produced primarily on larger scales than those probed by the EVN, and therefore is generated by star formation rather than an active galactic nucleus (AGN) – a result consistent with other methods used to identify the presence of SMBHs in these systems.

This paper tackles the problem of globally computing sub-Riemannian curves on the Euclidean group of motions SE(3). In particular we derive a global result for special sub-Riemannian curves for which their Hamiltonian satisfies a particular condition. The sub-Riemannian curves in this paper are defined in the context of a constrained optimal control problem. The Maximun Principle is then applied to this problem to yield the appropriate left-invariant quadratic Hamiltonian. A number of integrable quadratic Hamiltonians are identified. We then proceed to derive convenient expressions for sub-Riemannian curves in SE(3) that correspond to particular extreme curves. These equations are then used to compute sub-Riemannian curves that could potentially be used for motion planning of underwater vehicles.

Study Objectives: There is little evidence that patient weight is associated with pain response to morphine in the emergency department (ED). The primary outcome of this study is to identify demographic variables including patient weight that are associated with an adequate pain reduction after the first dose of morphine. Methods: A retrospective chart review of all patients with severe nontraumatic abdominal pain receiving intravenous morphine was conducted in our ED over a 3-month time period. Pain score, using an 11-point verbal numerical pain scale (0-10), was measured before and after each dose of morphine. Adequate response was defined as a ≥ 4-point reduction from baseline pain score. Results: A total of 105 patients were included in the analysis. Univariate logistic regression analyses stratified by dose (2 or 4 mg) showed that patient weight was not predictive of adequate pain response after the first dose of morphine (2 mg: odds ratio = 1; 95% confidence interval 0.97-1.03; P = .88; 4 mg: odds ratio = 1; 95% confidence interval 0.97-1.03; P = .86). Conclusions: Patient weight may not predict pain response to morphine in the ED. Dosing strategies based on patient weight may not be necessary in this patient population.

This paper considers the problem of planning optimal attitude motions for spacecraft. The extremal solutions that result from this optimization problem are characterized and their singularities identified. Following this these singularities are solved analytically inferring the form of particular optimal velocities. These particular solutions are then integrated and their corresponding motions derived independently of a local coordinate chart. These motions have the potential to be used as smooth, optimal reference trajectories for performing certain re-orientations for spacecraft.

We investigate the correlation between far-infrared (FIR) and radio luminosities in distant galaxies, a lynchpin of modern astronomy. We use data from the Balloon-borne Large Aperture Submillimetre Telescope (BLAST), Spitzer, the Large Apex BOlometer CamerA (LABOCA), the Very Large Array (VLA) and the Giant Metre-wave Radio Telescope (GMRT) in the Extended Chandra Deep Field South (ECDFS). For a catalogue of BLAST 250-micron-selected galaxies, we re-measure the 70--870-micron flux densities at the positions of their most likely 24-micron counterparts, which have a median [interquartile] redshift of 0.74 [0.25, 1.57]. From these, we determine the monochromatic flux density ratio, q_250 = log_10 (S_250micron / S_1400MHz), and the bolometric equivalent, q_IR. At z ~= 0.6, where our 250-micron filter probes rest-frame 160-micron emission, we find no evolution relative to q_160 for local galaxies. We also stack the FIR and submm images at the positions of 24-micron- and radio-selected galaxies. The difference between q_IR seen for 250-micron- and radio-selected galaxies suggests star formation provides most of the IR luminosity in ~< 100-uJy radio galaxies, but rather less for those in the mJy regime. For the 24-micron sample, the radio spectral index is constant across 0 < z < 3, but q_IR exhibits tentative evidence of a steady decline such that q_IR is proportional to (1+z)^(-0.15 +/- 0.03) - significant evolution, spanning the epoch of galaxy formation, with major implications for techniques that rely on the FIR/radio correlation. We compare with model predictions and speculate that we may be seeing the increase in radio activity that gives rise to the radio background.

A complete sample of 33 sources believed to be starbursts ("5.8micron-peakers") was selected in the (0.5 sq. deg.) J1046+56 field with selection criteria F_(24micron)>400muJy, the presence of a redshifted stellar emission peak at 5.8um, and r'(Vega)>23. The field, part of the SWIRE Lockman Hole field, benefits from very deep VLA/GMRT 20cm, 50cm, and 90cm radio data (all 33 sources are detected at 50cm), and deep 160micron and 70micron Spitzer data. The 33 sources, with photometric redshifts ~1.5-2.5, were observed at 1.2mm with IRAM-30m/MAMBO to an rms ~0.7-0.8mJy in most cases. Their millimeter, radio, 7-band Spitzer, and near-IR properties were jointly analyzed. The entire sample of 33 sources has an average 1.2mm flux density of 1.56+/-0.22mJy and a median of 1.61mJy, so the majority of the sources can be considered SMGs. Four sources have confirmed 4sigma detections, and nine were tentatively detected at the 3sigma level. Because of its 24micron selection, our sample shows systematically lower F_(1.2mm)/F_(24micron) flux ratios than classical SMGs, probably because of enhanced PAH emission. A median FIR SED was built by stacking images at the positions of 21 sources in the region of deepest Spitzer coverage. Its parameters are T_(dust)=37+/-8K, L_(FIR)=2.5x10^{12}Lo, and SFR=450Mo/yr. The FIR-radio correlation provides another estimate of L_(FIR) for each source, with an average value of 4.1x10^{12}Lo; however, this value may be overestimated because of some AGN contribution. Most of our targets are also luminous star-forming BzK galaxies which constitute a significant fraction of weak SMGs at 1.7, Comment: 23 pages, 12 figures + 1 figure in appendix Accepted in A&A on 01 September 2009

This note investigates the motion control of an autonomous underwater vehicle (AUV). The AUV is modeled as a nonholonomic system as any lateral motion of a conventional, slender AUV is quickly damped out. The problem is formulated as an optimal kinematic control problem on the Euclidean Group of Motions SE(3) , where the cost function to be minimized is equal to the integral of a quadratic function of the velocity components. An application of the maximum principle to this optimal control problem yields the appropriate Hamiltonian and the corresponding vector fields give the necessary conditions for optimality. For a special case of the cost function, the necessary conditions for optimality can be characterized more easily and we proceed to investigate its solutions. Finally, it is shown that a particular set of optimal motions trace helical paths. Throughout this note we highlight a particular case where the quadratic cost function is weighted in such a way that it equates to the Lagrangian (kinetic energy) of the AUV. For this case, the regular extremal curves are constrained to equate to the AUV's components of momentum and the resulting vector fields are the d'Alembert-Lagrange equations in Hamiltonian form.

In this paper we propose an optimal time-delayed feedback control (TDFC) for tracking unstable periodic orbits (UPOs). It is shown that TDFC will drive a trajectory onto a periodic orbit while minimising an integral of a cost function of the error in periodicity and the control effort. This optimal TDFC relies on the linearisation about the delayed trajectory not the UPO itself and therefore can be implemented without a priori knowledge of a reference orbit. This optimal TDFC is applied to the problem of tracking an unstable periodic orbit in the nonlinear equations describing the circular restricted three-body problem. The results of this investigation demonstrate that TDFC could efficiently drive a spacecraft onto a periodic orbit in the vicinity of a (UPO) halo orbit.

Purpose Docetaxel/estramustine is a known active regimen in hormonerefractory prostate cancer (HRPC). A phase II study was conducted to assess the safety and efficacy of docetaxel/estramustine combined with exisulind, an apoptotic antineoplastic drug. Patients and Methods Eighty men with chemotherapy-naive HRPC were enrolled in a multicenter, cooperative group study. The treatment regimen consisted of oral estramustine (280 mg 3 times daily for 5 days), docetaxel 70 mg/m 2 , oral exisulind (250 mg twice daily), oral dexamethasone (8 mg twice daily for 3 days), and oral warfarin (2 mg daily). Results Seventy-five eligible patients were treated with a median of 6 cycles of therapy. Fortyseven patients (62.7%; 95% CI, 50.7%-73.6%) had a ≤ 50% decline in prostate-specific antigen levels. Forty-six patients had measurable disease with 6 partial responses (13%; 95% CI, 4.9%-26.3%). The main grade 3/4 toxicities were neutrophils (79%), fatigue (15%), and thrombosis/embolism (10%). The median time to first progression was 5.1 months (95% CI, 4.4-6.3 months) and the median survival time was 17.8 months (95% CI, 14.7-20.1 months). Conclusion The combination of estramustine/docetaxel/exisulind was associated with significant thomboembolic toxicity despite prophylactic warfarin. The contribution of exisulind to toxicity is uncertain. Prostate-specific antigen decline, response rates, and progression-free and overall survival are similar to those reported with docetaxel/estramustine.

We present high-resolution interferometric imaging of LH850.02, the brightest 850- and 1200-micron submillimetre (submm) galaxy in the Lockman Hole. Our observations were made at 890 micron with the Submillimetre Array (SMA). Our high-resolution submm imaging detects LH850.02 at >6-sigma as a single compact (size < 1 arcsec or < 8 kpc) point source and yields its absolute position to ~0.2-arcsec accuracy. LH850.02 has two alternative radio counterparts within the SCUBA beam (LH850.02N & S), both of which are statistically very unlikely to be so close to the SCUBA source position by chance. However, the precise astrometry from the SMA shows that the submm emission arises entirely from LH850.02N, and is not associated with LH850.02S (by far the brighter of the two alternative identifications at 24-micron). Fits to the optical-infrared multi-colour photometry of LH850.02N & S indicate that both lie at z~3.3, and are therefore likely to be physically associated. At these redshifts, the 24 micron--to--submm flux density ratios suggest that LH850.02N has an Arp220-type starburst-dominated far-IR SED, while LH850.02S is more similar to Mrk231, with less dust-enshrouded star-formation activity, but a significant contribution at 24-micron (rest-frame ~5-6 micron) from an active nucleus. This complex mix of star-formation and AGN activity in multi-component sources may be common in the high redshift ultraluminous galaxy population, and highlights the need for precise astrometry from high resolution interferometric imaging for a more complete understanding., MNRAS, in press

We have produced sensitive, high-resolution radio maps of 12 SMGs in the Lockman Hole using combined MERLIN and VLA data at a frequency of 1.4 GHz. Integrating for 350hr yielded an r.m.s. noise of 6.0 uJy/beam and a resolution of 0.2-0.5". For the first time, wide-field data from the two arrays have been combined in the (u,v) plane and the bandwidth smearing response of the VLA data has been removed. All of the SMGs are detected in our maps as well as sources comprising a non-submm luminous control sample. We find evidence that SMGs are more extended than the general uJy radio population and that therefore, unlike in local ULIRGs, the starburst component of the radio emission is extended and not confined to the galactic nucleus. For the eight sources with redshifts we measure linear sizes between 1 and 8 kpc with a median of 5 kpc. Therefore, they are in general larger than local ULIRGs which may support an early-stage merger scenario for the starburst trigger. X-rays betray AGN in six of the 33 sources in the combined sample. All but one of these are in the control sample, suggesting a lower incidence of AGN amongst the submm-luminous galaxies which is, in turn, consistent with increased X-ray absorption in these dust-obscured starbursts. Only one of our sources is resolved into multiple, distinct components with our high-resolution data. Finally, compared to a previous study of faint radio sources in the GOODS-N field we find systematically smaller source sizes and no evidence for a tail extending to ~4". Possible reasons for this are discussed., In press at MNRAS. 12 pages. High-resolution PDF version available at http://www.roe.ac.uk/~rji/merlin.pdf

© 2015 Author(s). Attosecond X-ray pulses are short enough to capture snapshots of molecules undergoing nonadiabatic electron and nuclear dynamics at conical intersections (CoIns). We show that a stimulated Raman probe induced by a combination of an attosecond and a femtosecond pulse has a unique temporal and spectral resolution for probing the nonadiabatic dynamics and detecting the ultrafast (~4.5 fs) passage through a CoIn. This is demonstrated by a multiconfigurational self-consistent-field study of the dynamics and spectroscopy of the furan ring-opening reaction. Trajectories generated by surface hopping simulations were used to predict Attosecond Stimulated X-ray Raman Spectroscopy signals at reactant and product structures as well as representative snapshots along the conical intersection seam. The signals are highly sensitive to the changes in nonadiabatically coupled electronic structure and geometry.

We have exploited ALMA calibration observations to carry out a novel, wide and deep submm survey, ALMACAL. These calibration data comprise a large number of observations of calibrator fields in a variety of frequency bands and array configurations. Gathering together data acquired during multiple visits to many ALMA calibrators, it is possible to reach noise levels which allow the detection of faint dusty, star-forming galaxies (DSFGs) over a significant area. In this paper we outline our survey strategy and report the first results. We have analysed data for 69 calibrators, reaching depths of $\sim 25 \, {\rm \mu Jy \, beam^{-1}}$ at sub-arcsec resolution. Adopting a conservative approach based on $\geq 5 \sigma$ detections, we have found eight and 11 DSFGs in ALMA bands 6 and 7, respectively, with flux densities $S_{\rm 1.2 mm} \geq 0.2 \, {\rm mJy}$. The faintest galaxies would have been missed by even the deepest \emph{Herschel} surveys. Our cumulative number counts have been determined independently at 870 $\mu$m and 1.2 mm, from a sparse sampling of the astronomical sky, and are thus relatively free of cosmic variance. The counts are lower than reported previously by a factor of at least $2\times$. Future analyses will yield large, secure samples of DSFGs, with redshifts determined via detection of submm spectral lines. Uniquely, our strategy then allows morphological studies of very faint DSFGs - representative of more normal star-forming galaxies than conventional submm galaxies (SMGs) - in fields where self-calibration is feasible, yielding milliarcsecond spatial resolution., Comment: Submitted to ApJ

A facile protocol is developed for the preparation of thioimines from aldehydes and S-nitrosothiols.

In this paper a semi-analytical technique for generating quadrotor trajectories using the projection of sub-Riemannian curves on SE(3) onto ℝ3 is presented. The benefits of using these trajectories are that they have constant speed and acceleration magnitude, are smooth and analytically defined in terms of standard functions. Also, they are sub-optimal with respect to a weighted quadratic cost function of the translational and angular velocities. This paper shows, through simulation, that these curves are also dynamically feasible. In addition, a method for changing the velocity profile along these curves using time parametrisation, allowing for smooth rest-to-rest manoeuvres, is shown. An obstacle avoidance strategy using these analytically defined curves is demonstrated by producing multiple trajectories of different shapes. This is achieved by adding a final velocity perturbation to the error function that is minimised when generating the trajectory.

This paper presents a semi-analytical trajectory planning method for quadrotor UAVs. These trajectories are analytically defined, are constant in speed and sub-optimal with respect to a weighted quadratic cost function of the translational and angular velocities. A technique for concatenating the trajectories into multi-segment paths is demonstrated. These paths are smooth to the first derivative of the translational position and pass through defined waypoints. A method for detecting potential collisions by discretizing the path into a coarse mesh before using a numerical optimiser to determine the point of the path closest to the obstacle is presented. This hybrid method reduces the computation time when compared to discretizing the trajectory into a fine mesh and calculating the minimum distance. A tracking controller is defined and used to show that the paths are dynamically feasible and the typical magnitudes of the controller inputs required to fly them.

Cytochrome P450 enzymes are an important family of biocatalysts that oxidize chemically inert CH bonds. There are many unresolved questions regarding the catalytic reaction intermediates, in particular P450 Compound I (Cpd-I) and II (Cpd-II). By using simple molecular models, we simulate various X-ray spectroscopy signals, including X-ray absorption near-edge structure (XANES), resonant inelastic X-ray scattering (RIXS), and stimulated X-ray Raman spectroscopy (SXRS) of the low- and high-spin states of Cpd-I and II. Characteristic peak patterns are presented and connected to the corresponding electronic structures. These X-ray spectroscopy techniques are complementary to more conventional infrared and optical spectroscopy and they help to elucidate the evolving electronic structures of transient species along the reaction path.

We investigate computationally the valence electronic excitations of the amino acid glycine following a sudden nitrogen core ionization induced by an attosecond X-ray pump pulse. The molecule left in a superposition of cationic excited states is then probed by a second broadband X-ray pulse together with a narrowband pulse tuned to the carbon K-edge. Transient X-ray absorption and attosecond stimulated X-ray Raman signals are simulated and related to the evolution of the valence excited state wavepacket.

We present the results of a survey for intervening HI 21-cm absorbers at intermediate and low redshift (0180 K. A subset of our systems were also searched for OH absorption, but no detections were made., Comment: Accepted for publication in MNRAS, 13 pages with 10 figures

The Martian moon Phobos is becoming an appealing destination for future scientific missions. The orbital dynamics around this planetary satellite is particularly complex due to the unique combination of both small mass-ratio and length-scale of the Mars-Phobos couple: the resulting sphere of influence of the moon is very close to its surface, therefore both the classical two-body problem and circular restricted three-body problem (CR3BP) do not provide an accurate approximation to describe the spacecraft’s dynamics in the vicinity of Phobos. The aim of this paper is to extend the model of the CR3BP to consider the orbital eccentricity and the highly-inhomogeneous gravity field of Phobos, by incorporating the gravity harmonics series expansion into an elliptic R3BP, named ER3BP-GH. Following this, the dynamical substitutes of the Libration Point Orbits (LPOs) are computed in this more realistic model of the relative dynamics around Phobos, combining methodologies from dynamical systems theory and numerical continuation techniques. Results obtained show that the structure of the periodic and quasi-periodic LPOs differs substantially from the classical case without harmonics. Several potential applications of these natural orbits are presented to enable unique low-cost operations in the proximity of Phobos, such as close-range observation, communication, and passive radiation shielding for human spaceflight. Furthermore, their invariant manifolds are demonstrated to provide high-performance natural landing and take-off pathways to and from Phobos’ surface, and transfers from and to Martian orbits. These orbits could be exploited in upcoming and future space missions targeting the exploration of this Martian moon.

Spacecraft play an increasingly important role in various areas of modern society, such as telecommunication, earth observation, and space exploration. It is estimated that there have been more than 7000 spacecrafts launched all over the world. Despite rigorous testing many of these spacecraft fail on orbit due to various reasons [1], which consequently often lead to the failure of the whole mission. According to [2], over 30% of spacecraft failures occur at the subsystem level of the Attitude and Orbit Control System (AOCS). Moreover about 50% of the AOCS failures are attributed to actuator errors. The purpose of this paper is to present an actuator fault-tolerant attitude control.

We present catalogues of faint 1.4-GHz radio sources from extremely-deep Very Large Array pointings in the Lockman Hole, the Hubble Deep Field North (HDF-N) and ELAIS N2. Our analysis of the HDF-N data has produced maps that are significantly deeper than those previously published and we have used these to search for counterparts to submm sources. For each of the fields we have derived normalised differential source counts and in the case of the HDF-N find no evidence for the previously-reported under-density of sources; our counts are entirely consistent with those found for the majority of other fields. The catalogues are available as an online supplement to this paper and the maps are also available for download., 10 pages, 6 figures. Accepted for publication in MNRAS. Full resolution versions of Fig. 3 are available from ftp://ftp.roe.ac.uk/pub/adb/vla_deep_fields/ . Catalogues and maps can be obtained from the same url

We analyse HST WFC3/$H_{160}$-band observations of a sample of 48 ALMA-detected submillimeter galaxies (SMGs) in the Extended Chandra Deep Field South field, to study their stellar morphologies and sizes. We detect 79$\pm$17% of the SMGs in the $H_{160}$-band imaging with a median sensitivity of 27.8 mag, and most (80%) of the non-detections are SMGs with 870$\mu$m fluxes of $S_{870} < $3 mJy. With a surface brightness limit of $\mu_H \sim $26 mag arcsec$^{-2}$, we find that 82$\pm$9% of the $H_{160}$-band detected SMGs at $z =$ 1-3 appear to have disturbed morphologies, meaning they are visually classified as either irregulars or interacting systems, or both. By determining a S\'ersic fit to the $H_{160}$ surface-brightness profiles we derive a median S\'ersic index of $n = $1.2$\pm$0.3 and a median half-light radius of $r_e = $4.4$^{+1.1}_{-0.5}$ kpc for our SMGs at $z = $1-3. We also find significant displacements between the positions of the $H_{160}$-component and 870$\mu$m emission in these systems, suggesting that the dusty star-burst regions and less-obscured stellar distribution are not co-located. We find significant differences in the sizes and the S\'ersic index between our $z = $2-3 SMGs and $z \sim $2 quiescent galaxies, suggesting a major transformation of the stellar light profile is needed in the quenching processes if SMGs are progenitors of the red-and-dead $z\sim$2 galaxies. Given the short-lived nature of SMGs, we postulate that the majority of the $z = $2-3 SMGs with $S_{870} \gtrsim $2 mJy are early/mid-stage major mergers., Comment: ApJ in press, 32 pages, 13 figures

Some microquasars are permanently bright radio sources while others are faint but produce powerful radio outbursts. Most of the X-ray binaries (XRB) however are very faint or undetected in the radio regime. The European VLBI Network (EVN) recently introduced the Mark5 recording system which allows data rates of up to 1 Gbit s -1 . This increases the sensitivity of the array significantly. We briefly describe recent developments in the EVN in terms of reliability of the network and also data quality. We demonstrate the power of the EVN in detecting sub-mJy radio sources with modest integration times (order of hours). This high sensitivity capability will permit the study of variable Galactic sources at milli-arcsecond resolution. An estimate is given for the lowest detectable mass of hypothetical intermediate-mass black holes (IMBH) in nearby galaxies, provided these are located in radio-jet systems analogous to microquasars and active galactic nuclei.

We present observations of CLASS B2108+213, the widest separation gravitational lens system discovered by the Cosmic Lens All-Sky Survey. Radio imaging using the VLA at 8.46 GHz and MERLIN at 5 GHz shows two compact components separated by 4.56 arcsec with a faint third component in between which we believe is emission from a lensing galaxy. 5-GHz VLBA observations reveal milliarcsecond-scale structure in the two lensed images that is consistent with gravitational lensing. Optical emission from the two lensed images and two lensing galaxies within the Einstein radius is detected in Hubble Space Telescope imaging. Furthermore, an optical gravitational arc, associated with the strongest lensed component, has been detected. Surrounding the system are a number of faint galaxies which may help explain the wide image separation. A plausible mass distribution model for CLASS B2108+213 is also presented., Comment: 9 pages, 8 figures, accepted for publication in MNRAS

We report the final results of the search for gravitationally lensed flat-spectrum radio sources found in the combination of CLASS (Cosmic Lens All Sky Survey) and JVAS (Jodrell-Bank VLA Astrometric Survey). VLA observations of 16,503 sources have been made, resulting in the largest sample of arcsec-scale lens systems available. Contained within the 16,503 sources is a complete sample of 11,685 sources having two-point spectral indices between 1.4 and 5 GHz flatter than -0.5 and 5 GHz flux densities $\geq$30 mJy. A subset of 8,958 sources form a well-defined statistical sample suitable for analysis of the lens statistics. We describe the systematic process by which 149 candidate lensed sources were picked from the statistical sample on the basis of possessing multiple compact components in the 0.2 arcsec-resolution VLA maps. Candidates were followed up with 0.05 arcsec resolution MERLIN and 0.003 arcsec VLBA observations at 5 GHz and rejected as lens systems if they failed well-defined surface brightness and/or morphological tests. Maps for all the candidates can be found on the World Wide Web at http://www.jb.man.ac.uk/research/gravlens/index.html We summarize the properties of each of the 22 gravitational lens systems in JVAS/CLASS. Twelve are double-image systems, nine are four-image systems and one is a six-image system. Thirteen constitute a statistically well-defined sample giving a point-source lensing rate of 1:690$\pm$190. The interpretation of the results in terms of the properties of the lensing galaxy population and cosmological parameters will be published elsewhere. (Abridged), v2: web link in the abstract fixed; some corrections made in section 6.1

The Cosmic Lens All-Sky Survey (CLASS) is an international collaborative program which has obtained high-resolution radio images of over 10000 flat-spectrum radio sources in order to create the largest and best studied statistical sample of radio-loud gravitationally lensed systems. With this survey, combined with detailed studies of the lenses found therein, constraints can be placed on the expansion rate, matter density, and dark energy (e.g. cosmological constant, quintessence) content of the Universe that are complementary to and independent of those obtained through other methods. CLASS is aimed at identifying lenses where multiple images are formed from compact flat-spectrum radio sources, which should be easily identifiable in the radio maps. Because CLASS is radio-based, dust obscuration in lensing galaxies is not a factor, and the relative insensitivity of the instrument to environmental conditions leads to nearly uniform sensitivity and resolution over the entire survey. In four observing seasons from 1994-1999, CLASS has observed 13783 radio sources with the VLA at 8.4 GHz at 0.2 arcsecond resolution. When combined with the JVAS survey, the CLASS sample contains over 16,000 images. A complete sample of 11685 flat-spectrum sources was observed, selected from GB6 catalogue at 4.85 GHz and the NVSS at 1.4 GHz. So far, CLASS has found 16 new gravitational lens systems, and the JVAS/CLASS survey contains a total of 22 lenses. (Abridged), 14 pages, 9 figures, accepted for publication in MNRAS

We report the discovery of a new gravitational lens system from the CLASS survey. Radio observations with the VLA, the WSRT and MERLIN show that the radio source B0850+054 is comprised of two compact components with identical spectra, a separation of 0.7 arcsec and a flux density ratio of 6:1. VLBA observations at 5 GHz reveal structures that are consistent with the gravitational lens hypothesis. The brighter of the two images is resolved into a linear string of at least six sub-components whilst the weaker image is radially stretched towards the lens galaxy. UKIRT K-band imaging detects an 18.7 mag extended object, but the resolution of the observations is not sufficient to resolve the lensed images and the lens galaxy. Mass modelling has not been possible with the present data and the acquisition of high-resolution optical data is a priority for this system., Comment: 5 pages, 4 figures, accepted for publication in MNRAS

A new two-image gravitational lens system has been discovered as a result of the Cosmic Lens All-Sky Survey (CLASS). Radio observations with the VLA, MERLIN and the VLBA at increasingly higher resolutions all show two components with a flux density ratio of ~7:1 and a separation of 1.34". Both components are compact and have the same spectral index. Followup observations made with the VLA at 8.4 GHz show evidence of a feature to the south-east of the brighter component and a corresponding extension of the weaker component to the north-west. Optical observations with the WHT show ~1.7" extended emission aligned in approximately the same direction as the separation between the radio components with an R-band magnitude of 21.8 +/- 0.4., 6 pages, 5 figures, accepted by MNRAS

Purpose. To determine the optimal dose of combination topotecan, cisplatin, and gemcitabine in advanced non-small cell lung cancer patients. Materials and Methods. This single-center, single-practice, phase I trial enrolled chemotherapy-naïve patients with inoperable stage IIIB/IV disease. Initial treatment was topotecan (0.5-2.0 mg/m2), cisplatin (20 mg/m2), and gemcitabine (1,000 mg/m2) on days 1, 8, and 15 of a 28-day cycle. Dose-limiting thrombocytopenia at week 3 necessitated less frequent gemcitabine dosing (days 1 and 15 of each cycle). Thereafter, topotecan dose escalation proceeded to the target dose of 2 mg/m2. Results. Thirty patients were enrolled and evaluable for toxicity assessment. Treatment was extremely well tolerated: only one grade 4 adverse event (leukopenia); no hospitalizations for treatment-related toxicities; no fever/neutropenia. Although no dose-limiting toxicities developed, 1.75 mg/m2 topotecan is considered optimal and recommended for further study because it was well tolerated, active, and did not require dose adjustments or delays in therapy. Eleven of 29 (38%) evaluable patients achieved a partial response. Median survival was 38 weeks (range 4-110 weeks), median progression-free survival was 17 weeks, and the 1-year survival rate was 33%. Two patients remain alive after 108-122 weeks of follow-up. Conclusion. A 28-day cycle of topotecan (1.75 mg/m2 days 1, 8, 15), cisplatin (20 mg/m2 days 1, 8, 15), and gemcitabine (1,000 mg/m2 days 1, 15) was a safe and well-tolerated outpatient treatment for advanced non-small cell lung cancer. The favorable preliminary efficacy and safety of this regimen suggest that further study in phase II trials, including quality-of-life end points, is warranted.

© 2014 American Chemical Society. Long-range electron transfer (ET) is a crucial step in many energy conversion processes and biological redox reactions in living organisms. We show that newly developed X-ray pulses can directly probe the evolving oxidation states and the electronic structure around selected atoms with detail not available through conventional time-resolved infrared or optical techniques. This is demonstrated in a simulation study of the stimulated X-ray Raman (SXRS) signals in Re-modified azurin, which serves as a benchmark system for photoinduced ET in proteins. Nonlinear SXRS signals offer a direct novel window into the long-range ET mechanism. (Graph Presented).

Hydrogen sulfide (H2S) is a newly recognized signaling molecule with very potent cytoprotective actions. The fields of H2S physiology and pharmacology have been rapidly growing in recent years, but a number of fundamental issues must be addressed to advance our understanding of the biology and clinical potential of H2S in the future. Hydrogen sulfide releasing agents (also known as H2S donors) have been widely used in these fields. These compounds are not only useful research tools, but also potential therapeutic agents. It is therefore important to study the chemistry and pharmacology of exogenous H2S and to be aware of the limitations associated with the choice of donors used to generate H2S in vitro and in vivo. In this review we summarized the developments and limitations of currently available donors including H2S gas, sulfide salts, garlic-derived sulfur compounds, Lawesson's reagent/analogs, 1,2-dithiole-3-thiones, thiol-activated donors, photo-caged donors, and thioamino acids. Some biological applications of these donors were also discussed.

We investigate computationally the valence electronic excitations of the amino acid glycine prepared by a sudden nitrogen core ionization induced by an attosecond X-ray pump pulse. The created superposition of cationic excited states is probed by two-dimensional transient X-ray absorption and by three dimensional attosecond stimulated X-ray Raman signals. The latter, generated by applying a second broadband X-ray pulse combined with a narrowband pulse tuned to the carbon K-edge, reveal the complex coupling between valence and core-excited manifolds of the cation. © the Partner Organisations 2014.

The transition from construction to full operations of the Atacama Large Millimeter/submillimeter Array (ALMA) brings the challenge to have not only software subsystems that are functional and stable but also to develop a system that works flawlessly as a single entity from proposal preparation to the delivery of the final data products to ALMA users. This is especially challenging as the different subsystems have to be constantly updated and improved to accommodate new observing modes and increasing capabilities. We present recent progress and future initiatives in the different offline subsystems that are currently being developed and used in ALMA operations: proposal preparation, submission and observation preparation (Observing Tool and submission server), proposal review process (Ph1M), project tracking (Project Tracker, Life Cycle), observation bookkeeping (Shift Log Tool), calibrator database (Source Catalogue), monitor and control of observations (Operations Monitoring and Control tool), dynamic scheduler, data reduction pipeline, quality assurance and trend analysis (AQUA), archive, as well as additional user support systems such as the Science Portal.

The ALMA Regional Centres (ARCs) form the interface between the ALMA observatory and the user community from the proposal preparation stage to the delivery of data and their subsequent analysis. The ARCs provide critical services to both the ALMA operations in Chile and to the user community. These services were split by the ALMA project into core and additional services. The core services are financed by the ALMA operations budget and are critical to the successful operation of ALMA. They are contractual obligations and must be delivered to the ALMA project. The additional services are not funded by the ALMA project and are not contractual obligations, but are critical to achieve ALMA full scientific potential. A distributed network of ARC nodes (with ESO being the central ARC) has been set up throughout Europe at the following seven locations: Bologna, Bonn-Cologne, Grenoble, Leiden, Manchester, Ondrejov, Onsala. These ARC nodes are working together with the central node at ESO and provide both core and additional services to the ALMA user community. This paper presents the European ARC, and how it operates in Europe to support the ALMA community. This model, although complex in nature, is turning into a very successful one, providing a service to the scientific community that has been so far highly appreciated. The ARC could become a reference support model in an age where very large collaborations are required to build large facilities, and support is needed for geographically and culturally diverse communities.

Using a quantum electrodynamic framework, we calculate the off-resonant scattering of a broadband X-ray pulse from a sample initially prepared in an arbitrary superposition of electronic states. The signal consists of single-particle (incoherent) and two-particle (coherent) contributions that carry different particle form factors that involve different material transitions. Single-molecule experiments involving incoherent scattering are more influenced by inelastic processes compared to bulk measurements. The conditions under which the technique directly measures charge densities (and can be considered as diffraction) as opposed to correlation functions of the charge-density are specified. The results are illustrated with time- and wavevector-resolved signals from a single amino acid molecule (cysteine) following an impulsive excitation by a stimulated X-ray Raman process resonant with the sulfur K-edge. Our theory and simulations can guide future experimental studies on the structures of nano-particles and proteins. © 2014 AIP Publishing LLC.

One of the challenges of Active Debris Removal is related to the tumbling of the target satellite, when the chaser spacecraft has to approach and capture it. This paper presents the ASEM (Attitude Stabilization Electromagnetic Module) concept for detumbling debris in a low Earth orbit with the intention of mitigating risk during capture operations. This paper presents a preliminary design of a system whose purpose is to stabilize a target’s attitude, using an external module equipped with magnetorquers. The device, initially carried by the chaser spacecraft, is attached to the body of the target satellite. The magnetorquers are then used to detumble the target so that the chaser spacecraft can perform a safe approach prior to capture. A simplified model is used in the initial design phase to optimize the mass of the system and to size the torque rods and power source. Alternative methods for attaching the ASEM to the target from the chaser spacecraft are discussed. In addition a novel magnetic control law suitable for this application is presented. The feasibility of the concept is tested in simulations using a model based on Envisat (assuming that the ASEM is already attached to the target). Results show that a module weighing less than 20 kg can stabilize an 8-ton satellite initially rotating at 1 rpm in 21 days.

This paper investigates the natural dynamics of a space multibody system in orbit around a celestial body using modern dynamical systems theory. In particular Lyapunov Characteristic Exponent (LCE) maps, which are used in celestial mechanics and fluid dynamics, are here applied to a multi-body system to analyse different qualitative behaviours. Complemented with phase diagrams and Poincare maps, LCE maps are shown to be an extremely useful global visualisation tool. Such a map reduces the order of the problem, condensing quantities of information into a lower-dimensional image. Here, a simple example is considered to demonstrate the usefulness of LCE maps with the aim of using it on more complex, realistic cases in the future. For this simple example a Hamiltonian formulation is derived to facilitate an analytical analysis of the systems equilibria and their nonlinear stability and to aid the validation of the numerical results.

This article provides a method for finding initial conditions for perturbed frozen orbits around inhomogeneous fast rotating asteroids. These orbits can be used as reference trajectories in missions that require close inspection of any rigid body. The generalized perturbative procedure followed exploits the analytical methods of relegation of the argument of node and Delaunay normalisation to arbitrary order. These analytical methods are extremely powerful but highly computational. The gravitational potential of the heterogeneous body is firstly stated, in polar-nodal coordinates, which takes into account the coefficients of the spherical harmonics up to an arbitrary order. Through the relegation of the argument of node and the Delaunay normalization, a series of canonical transformations of coordinates is found, which reduces the Hamiltonian describing the system to a integrable, two degrees of freedom Hamiltonian plus a truncated reminder of higher order. Setting eccentricity, argument of pericenter and inclination of the orbit of the truncated system to be constant, initial conditions are found, which evolve into frozen orbits for the truncated system. Using the same initial conditions yields perturbed frozen orbits for the full system, whose perturbation decreases with the consideration of arbitrary homologic equations in the relegation and normalization procedures. Such procedure can be automated for the first homologic equation up to the consideration of any arbitrary number of spherical harmonics coefficients. The project has been developed in collaboration with the European Space Agency (ESA).

Energy and electron transfer processes in molecular complexes can be measured at unprecedented spatial and temporal resolution by novel X-ray spectroscopy techniques. Multidimensional broadband X-ray signals are simulated for a metalloporphyrin dimer and a Re-modified azurin model system of long-range biological electron transfer.

The development of multi-joint-spacecraft mission concepts calls for a deeper understanding of their nonlinear dynamics to inform and enhance system design. This paper presents a study of a three-finite-shape rigid-body system under the action of an ideal central gravitational field. The aim is to gain an insight into the natural dynamics. The Hamiltonian dynamics is derived and used to identify relative attitude equilibria of the system with respect to the orbital reference frame. Then a numerical investigation of the behaviour far from the equilibria is provided using tools from modern dynamical systems theory such as energy methods, phase portraits and Poincarè maps. Results reveal a complex structure of the configuration manifold underlying the dynamics as well as the existence of connections between some of the equilibria. Stable equilibrium configurations appear to be surrounded by very narrow regions of regular and quasi-regular motions. Trajectories evolve on chaotic motions in the rest of the domain.

The orbital dynamics around the Libration points of the classical circular restricted three-body problem (CR3BP) have been investigated in detail: in the last few decades, dynamical systems theory has provided invaluable analytical and numerical tools for understanding the dynamics of Libration Point Orbits (LPOs). The aim of this paper is to extend the model of the CR3BP to derive the LPOs in the vicinity of the Martian moon Phobos, which is becoming an appealing destination for scientific missions. The case of Phobos is particularly extreme, since the combination of both small mass-ratio and length-scale moves the collinear Libration manifold close to the moon’s surface. Thus, a model of this system must consider additional dynamical perturbations, in particular the complete gravity field of Phobos, which is highly-inhomogeneous. This is accomplished using a spherical harmonics series expansion, deriving an enhanced elliptic three-body model. In this paper, we show how methodologies from dynamical systems theory are applied in differential correction continuation schemes to this proposed nonlinear model of the dynamics near Phobos, to derive the structure of the dynamical substitutes of the LPOs in this new system. Results obtained show that the structure of the LPOs differs substantially from the classical case without harmonics. The proposed methodology allows us to identify natural periodic and quasi-periodic orbits that would provide unique low-cost opportunities for close-range observations around Phobos and high-performance landing/take-off pathways to and from Phobos’ surface, which could be exploited in upcoming missions targeting the exploration of this Martian moon.

© 2013 Author(s). Nonlinear all-X-ray signals that involve large core-atom separation compared to the X-ray wavelengths may not be described by the dipole approximation since they contain additional phase factors. Expressions for the rotationally averaged 2D X-ray photon echo signals from randomly oriented systems that take this positiondependent phase into account for arbitrary ratio between the core separation and the resonant wavelength are presented. Application is made to the Se K-edge of a selenium dipeptide system.

SUMMARYThis paper presents a motion planning method for a simple wheeled robot in two cases: (i) where translational and rotational speeds are arbitrary, and (ii) where the robot is constrained to move forwards at unit speed. The motions are generated by formulating a constrained optimal control problem on the Special Euclidean group SE(2). An application of Pontryagin's maximum principle for arbitrary speeds yields an optimal Hamiltonian which is completely integrable in terms of Jacobi elliptic functions. In the unit speed case, the rotational velocity is described in terms of elliptic integrals, and the expression for the position is reduced to quadratures. Reachable sets are defined in the arbitrary speed case, and a numerical plot of the time-limited reachable sets is presented for the unit speed case. The resulting analytical functions for the position and orientation of the robot can be parametrically optimised to match prescribed target states within the reachable sets. The method is shown to be easily adapted to obstacle avoidance for static obstacles in a known environment.

Measurement of the time delay between multiple images of a gravitational lens system is potentially an accurate method of determining the Hubble constant over cosmological distances. One of the most promising candidates for an application of this technique is the system B0218+357 which was found in the Jodrell Bank/VLA Astrometric Survey (JVAS). This system consists of two images of a compact radio source, separated by 335 milliarcsec, and an Einstein ring which can provide a strong constraint on the mass distribution in the lens. We present here the results of a three-month VLA monitoring campaign at two frequencies. The data are of high quality and both images show clear variations in total flux density, percentage polarization and polarization position angle at both frequencies. The time delay between the variations in the two images has been calculated using a chi-squared minimization to be 10.5+/-0.4 days at 95 per cent confidence, with the error being derived from Monte-Carlo simulations of the light curves. Although mass modelling of the system is at a preliminary stage, taking the lensing galaxy to be a singular isothermal ellipsoid and using the new value for the time delay gives a value for the Hubble constant of 69+13/-19 km/s/Mpc, again at 95 per cent confidence., Accepted for publication in MNRAS. 12 pages, 10 included PostScript figures. Data can be obtained from http://multivac.jb.man.ac.uk:8000/ceres/data_from_papers/0218.html

An African American individual with early onset breast cancer has a unique BRCA1 germline mutation, E1644X, that truncates the protein's carboxy terminal region. DNA sequencing for E1644X mutation and five BRCA1 exon-11 single nucleotide polymorphisms showed tumor LOH. Clinical history suggests paternal transmission of the deleterious allele, and tumor polymorphisms provide some insight into the ancestral origins of the mutation.