Is there evidence for change to collagen within parchment samples after exposure to an X-ray dose during high contrast X-ray microtomography? a multi technique investigation

OA MOnitor ExerciseOA MOnitor ExerciseOA MOnitor ExerciseOA MOnitor ExerciseThe potential use of high contrast X-ray microtomography (XMT) for the reading of fragile historic documents without the need to physically unravel them is a new analytical imaging development in the field of conservation however, it is important to first assess if there is any evidence of change in the parchment structure during scanning by XMT. Modern and historic parchment samples were exposed to X-rays using the high contrast XMT equipment. Attenuated Total Reflection Fourier Transform Infra-red Spectroscopy (ATR-FTIR), SDS-polyacrylamide gel electrophoresis (SDS-PAGE), Near-infrared Spectroscopy (NIR) and X-ray diffraction (XRD) were utilised to investigate whether there is any evidence for change to collagen within parchment samples after exposure to XMT. Results show that the inherent differences in the parchment structure due to the material source, production and storage appear to produce larger differences than that due to the exposure to XMT. This indicates that XMT may be a suitable technique for data recovery from parchment samples that cannot be unrolled.This research was supported by funding received from the Engineering, Physical Sciences Research Council EP/G007845/1 and EP/G010110/1

Graphical programming: A systems approach for telerobotic servicing of space assets

Satellite servicing is in many ways analogous to subsea robotic servicing in the late 1970's. A cost effective, reliable, telerobotic capability had to be demonstrated before the oil companies invested money in deep water robot serviceable production facilities. In the same sense, aeronautic engineers will not design satellites for telerobotic servicing until such a quantifiable capability has been demonstrated. New space servicing systems will be markedly different than existing space robot systems. Past space manipulator systems, including the Space Shuttle's robot arm, have used master/slave technologies with poor fidelity, slow operating speeds and most importantly, in-orbit human operators. In contrast, new systems will be capable of precision operations, conducted at higher rates of speed, and be commanded via ground-control communication links. Challenge presented by this environment include achieving a mandated level of robustness and dependability, radiation hardening, minimum weight and power consumption, and a system which accommodates the inherent communication delay between the ground station and the satellite. There is also a need for a user interface which is easy to use, ensures collision free motions, and is capable of adjusting to an unknown workcell (for repair operations the condition of the satellite may not be known in advance). This paper describes the novel technologies required to deliver such a capability

A Sensitive Search for Variability in Late L Dwarfs: The Quest for Weather

We have conducted a photometric monitoring program of three field late L brown dwarfs (DENIS-P J0255-4700, 2MASS J0908+5032, and 2MASS J2244+2043) looking for evidence of nonaxisymmetric structure or temporal variability in their photospheres. The observations were performed using Spitzer IRAC 4.5 and 8 μm bandpasses and were designed to cover at least one rotational period of each object; 1 σ rms uncertainties of less than 3 mmag at 4.5 μm and around 9 mmag at 8 μm were achieved. Two out of the three objects studied exhibit some modulation in their light curves at 4.5 μm—but not 8 μm—with periods of 7.4 hr (DENIS 0255) and 4.6 hr (2MA 2244) and peak-to-peak amplitudes of 10 and 8 mmag. Although the lack of detectable 8 μm variation suggests an instrumental origin for the detected variations, the data may nevertheless still be consistent with intrinsic variability, since the shorter wavelength IRAC bandpasses probe more deeply into late L dwarf atmospheres than the longer wavelengths. A cloud feature occupying a small percentage (1%-2%) of the visible hemisphere could account for the observed amplitude of variation. If, instead, the variability is indeed instrumental in origin, then our nonvariable L dwarfs could be either completely covered with clouds or objects whose clouds are smaller and uniformly distributed. Such scenarios would lead to very small photometric variations. Follow-up IRAC photometry at 3.6 and 5.8 μm bandpasses should distinguish between the two cases. In any event, the present observations provide the most sensitive search to date for structure in the photospheres of late L dwarfs at mid-IR wavelengths, and our photometry provides stringent upper limits to the extent to which the photospheres of these transition L dwarfs are structured

The Ultrasensitivity of Living Polymers

Synthetic and biological living polymers are self-assembling chains whose chain length distributions (CLDs) are dynamic. We show these dynamics are ultrasensitive: even a small perturbation (e.g. temperature jump) non-linearly distorts the CLD, eliminating or massively augmenting short chains. The origin is fast relaxation of mass variables (mean chain length, monomer concentration) which perturbs CLD shape variables before these can relax via slow chain growth rate fluctuations. Viscosity relaxation predictions agree with experiments on the best-studied synthetic system, alpha-methylstyrene.Comment: 4 pages, submitted to Phys. Rev. Let

A Spitzer/IRAC Search for Substellar Companions of the Debris Disk Star epsilon Eridani

We have used the InfraRed Array Camera (IRAC) onboard the Spitzer Space telescope to search for low mass companions of the nearby debris disk star epsilon Eridani. The star was observed in two epochs 39 days apart, with different focal plane rotation to allow the subtraction of the instrumental Point Spread Function, achieving a maximum sensitivity of 0.01 MJy/sr at 3.6 and 4.5 um, and 0.05 MJy/sr at 5.8 and 8.0 um. This sensitivity is not sufficient to directly detect scattered or thermal radiation from the epsilon Eridani debris disk. It is however sufficient to allow the detection of Jovian planets with mass as low as 1 MJ in the IRAC 4.5 um band. In this band, we detected over 460 sources within the 5.70 arcmin field of view of our images. To test if any of these sources could be a low mass companion to epsilon Eridani, we have compared their colors and magnitudes with models and photometry of low mass objects. Of the sources detected in at least two IRAC bands, none fall into the range of mid-IR color and luminosity expected for cool, 1 Gyr substellar and planetary mass companions of epsilon Eridani, as determined by both models and observations of field M, L and T dwarf. We identify three new sources which have detections at 4.5 um only, the lower limit placed on their [3.6]-[4.5] color consistent with models of planetary mass objects. Their nature cannot be established with the currently available data and a new observation at a later epoch will be needed to measure their proper motion, in order to determine if they are physically associated to epsilon Eridani.Comment: 36 pages, to be published on The Astrophysical Journal, vol. 647, August 200

Amyotrophic lateral sclerosis-motor neuron disease, monoclonal gammopathy, hyperparathyroidism, and B12 deficiency: case report and review of the literature

<p>Abstract</p> <p>Introduction</p> <p>Amyotrophic lateral sclerosis (the most common form of motor neuron disease) is a progressive and devastating disease involving both lower and upper motor neurons, typically following a relentless path towards death. Given the gravity of this diagnosis, all efforts must be made by the clinician to exclude alternative and more treatable entities. Frequent serology testing involves searching for treatable disorders, including vitamin B12 deficiency, parathyroid anomalies, and monoclonal gammopathies.</p> <p>Case presentation</p> <p>We present the case of a 78-year-old Caucasian man with all three of the aforementioned commonly searched for disorders during an investigation for amyotrophic lateral sclerosis.</p> <p>Conclusions</p> <p>The clinical utility of these common tests and what they ultimately mean in patients with amyotrophic lateral sclerosis is discussed, along with a review of the literature.</p

Patterns of Recovery from Severe Mental Illness: A Pilot Study of Outcomes

We performed a pilot study examining the patterns of recovery from severe mental illness in a model integrated service delivery system using measures from the Milestones of Recovery Scale (MORS), a valid and reliable measure of recovery outcomes which ranges from 1 to 8 (8 levels). For purposes of presentation, we constructed an aggregate MORS (6 levels) where the levels are described as follows: (1) extreme risk; (2) unengaged, poorly self-coordinating; (3) engaged, poorly self-coordinating; (4) coping and rehabilitating; (5) early recovery, and (6) self reliant. We analyzed MORS data on individuals followed over time from The Village in Long Beach, California (658 observations). Using Markov Chains, we estimated origin-destination transition probabilities, simulating recovery outcomes for 100 months. Our models suggest that after 12 months only 8% of “extreme risk” clients remain such. Over 40% have moved to “engaged, poorly self-coordinating.” After 2 years, almost half of the initial “extreme Risk” clients are “coping/rehabilitating”, “early recovery” or “Self reliant.” Most gains occur within 2 years

Discovery of Two T Dwarf Companions with the Spitzer Space Telescope

We report the discovery of T dwarf companions to the nearby stars HN Peg (G0V, 18.4 pc, ~0.3 Gyr) and HD 3651 (K0V, 11.1 pc, ~7 Gyr). During an ongoing survey of 5'x5' fields surrounding stars in the solar neighborhood with IRAC aboard the Spitzer Space Telescope, we identified these companions as candidate T dwarfs based on their mid-IR colors. Using near-IR spectra obtained with SpeX at the NASA IRTF, we confirm the presence of methane absorption that characterizes T dwarfs and measure spectral types of T2.5+/-0.5 and T7.5+/-0.5 for HN Peg B and HD 3651 B, respectively. By comparing our Spitzer data to images from 2MASS obtained several years earlier, we find that the proper motions of HN Peg B and HD 3651 B are consistent with those of the primaries, confirming their companionship. HN Peg B and HD 3651 B have angular separations of 43.2" and 42.9" from their primaries, which correspond to projected physical separations of 795 and 476 AU, respectively. A comparison of their luminosities to the values predicted by theoretical evolutionary models implies masses of 0.021+/-0.009 and 0.051+/-0.014 Msun for HN Peg B and HD 3651 B. In addition, the models imply an effective temperature for HN Peg B that is significantly lower than the values derived for other T dwarfs at similar spectral types, which is the same behavior reported by Metchev & Hillenbrand for the young late-L dwarf HD 203030 B. Thus, the temperature of the L/T transition appears to depend on surface gravity. Meanwhile, HD 3651 B is the first substellar companion directly imaged around a star that is known to harbor a close-in planet from RV surveys. The discovery of this companion supports the notion that the high eccentricities of close-in planets like the one near HD 3651 may be the result of perturbations by low-mass companions at wide separations.Comment: Astrophysical Journal, in pres