Size determination of the Centaur Chariklo from millimeter-wavelength bolometer observations

Using the Max-Planck Millimeter Bolometer Array (MAMBO) at the IRAM 30m telescope we detected emission at 250 GHz from the Centaur Chariklo (1997 CU26). The observed continuum flux density implies a photometric diameter of 273 km. The resulting geometric albedo is 0.055, somewhat higher than expected from a comparison with most of the other few Centaurs and cometary nuclei for which such data are available.Comment: 4 pages, 1 Postscript figure, to appear in Astronomy & Astrophysic

The Invisible Monster Has Two Faces: Observations of Є Aurigae with the Herschel Space Observatory

We present Herschel Space Observatory photometric observations of the unique, long-period eclipsing binary star Є Aurigae. Its extended spectral energy distribution is consistent with our previously published cool (550 K) dust disk model. We also present an archival infrared spectral energy distribution of the side of the disk facing the bright F-type star in the binary, which is consistent with a warmer (1150 K) disk model. The lack of strong molecular emission features in the Herschel bands suggests that the disk has a low gas-to-dust ratio. The spectral energy distribution and Herschel images imply that the 250 GHz radio detection reported by Altenhoff et al. is likely contaminated by infrared-bright, extended background emission associated with a nearby nebular region and should be considered an upper limit to the true flux density of Є Aur

Effects of Interaction with an Immersive Virtual Environment on Near-field Distance Estimates

Distances are regularly underestimated in immersive virtual environments (IVEs) (Witmer & Kline, 1998; Loomis & Knapp, 2003). Few experiments, however, have examined the ability of calibration to overcome distortions of depth perception in IVEs. This experiment is designed to examine the effect of calibration via haptic and visual feedback on distance estimates in an IVE. Participants provided verbal and reaching distance estimates during three sessions; a baseline measure without feedback, a calibration session with visual and haptic feedback, and finally a post-calibration session without feedback. Feedback was shown to calibrate distance estimates within an IVE. Discussion focused on the possibility that costly solutions and research endeavors seeking to remedy the compression of distances may become less necessary if users are simply given the opportunity to use manual activity to calibrate to the IVE

Perceiving Soft Tissue Break Points in the Presence of Friction

In minimally invasive surgery (MIS), surgeons face several perceptual challenges due to the remote interaction with the environment, such as distorted haptic feedback through the instruments due to friction produced from the rubber trocar sealing mechanisms at the incision site. As a result, surgeons sometimes unintentionally damage healthy tissues during MIS due to excessive force. Research has demonstrated that useful information is available in the haptic array regarding soft tissues, which allows novices to successfully perceive the penetration distance remaining until a material will fail based on displacement and reactionary forces of simulated tissues using a haptic invariant, Distance-to-Break (DTB). Attunement and calibration training was used in the current study to investigate whether observers are able to identify material break points in nonlinear compliant materials through haptic force application, while ignoring haptic stimulation not lawfully related to the properties specifying DTB, including friction. A pretest, feedback, posttest, and transfer-of-training phase design allowed participants to probe four virtually simulated materials at varying levels of friction: no friction, low friction, and high friction in the first experiment, and pull the simulated tissues in the second experiment to investigate if perception of DTB generalizes to other tasks used in MIS. Experiment 1 revealed that sensitivity to DTB can be improved through training, even in the presence of friction, and that friction may assist observers to perceive fragile tissues that otherwise would be below perceptual threshold. Experiment 2 revealed that attunement and calibration to DTB also transfers to pulling motions

Assigning confidence scores to homoeologs using fuzzy logic.

In polyploid genomes, homoeologs are a specific subtype of homologs, and can be thought of as orthologs between subgenomes. In Orthologous MAtrix, we infer homoeologs in three polyploid plant species: upland cotton (Gossypium hirsutum), rapeseed (Brassica napus), and bread wheat (Triticum aestivum). While we can typically recognize the features of a "good" homoeolog prediction (a consistent evolutionary distance, high synteny, and a one-to-one relationship), none of them is a hard-fast criterion. We devised a novel fuzzy logic-based method to assign confidence scores to each pair of predicted homoeologs. We inferred homoeolog pairs and used the new and improved method to assign confidence scores, which ranged from 0 to 100. Most confidence scores were between 70 and 100, but the distribution varied between genomes. The new confidence scores show an improvement over our previous method and were manually evaluated using a subset from various confidence ranges

Searching for new hypercompact HII regions

Hypercompact (HC) HII regions are, by nature, very young HII regions, associated with the earliest stages of massive star formation. They may represent the transition phase as an early B-type star grows into an O-type star. Unfortunately, so few HCHII regions are presently known that their general attributes and defining characteristics are based on small number statistics. A larger sample is needed for detailed studies and good statistics. Class II methanol masers are one of the best indicators of the early stages of massive star formation. Using the Arecibo Methanol Maser Galactic Plane Survey - the most sensitive blind survey for 6.7 GHz methanol masers to date - we selected 24 HCHII region candidates. We made EVLA continuum observations at 3.6 and 1.3 cm to search for HCHII regions associated with these masers. We identified six potential HCHII regions in our sample based on the presence of optically thick free-free emission. Overall, we find that 30% of the methanol masers have an associated centimeter radio continuum source (separation less than 0.1 pc), which is in general agreement with previous studies.Comment: Accepted for publication in ApJL, in the Special Issue of the EVL

Partial Homology Relations - Satisfiability in terms of Di-Cographs

Directed cographs (di-cographs) play a crucial role in the reconstruction of evolutionary histories of genes based on homology relations which are binary relations between genes. A variety of methods based on pairwise sequence comparisons can be used to infer such homology relations (e.g.\ orthology, paralogy, xenology). They are \emph{satisfiable} if the relations can be explained by an event-labeled gene tree, i.e., they can simultaneously co-exist in an evolutionary history of the underlying genes. Every gene tree is equivalently interpreted as a so-called cotree that entirely encodes the structure of a di-cograph. Thus, satisfiable homology relations must necessarily form a di-cograph. The inferred homology relations might not cover each pair of genes and thus, provide only partial knowledge on the full set of homology relations. Moreover, for particular pairs of genes, it might be known with a high degree of certainty that they are not orthologs (resp.\ paralogs, xenologs) which yields forbidden pairs of genes. Motivated by this observation, we characterize (partial) satisfiable homology relations with or without forbidden gene pairs, provide a quadratic-time algorithm for their recognition and for the computation of a cotree that explains the given relations

Expanded Very Large Array observations of the H66{\alpha} and He66{\alpha} recombination lines toward MWC 349A

We have used the greatly enhanced spectral capabilities of the Expanded Very Large Array to observe both the 22.3 GHz continuum emission and the H66{\alpha} recombination line toward the well-studied Galactic emission-line star MWC 349A. The continuum flux density is found to be 411 $\pm$ 41 mJy in good agreement with previous determinations. The H66{\alpha} line peak intensity is about 25 mJy, and the average line-to-continuum flux ratio is about 5%, as expected for local thermodynamic equilibrium conditions. This shows that the H66{\alpha} recombination line is not strongly masing as had previously been suggested, although a moderate maser contribution could be present. The He66{\alpha} recombination line is also detected in our observations; the relative strengths of the two recombination lines yield an ionized helium to ionized hydrogen abundance ratio y+ = 0.12 $\pm$ 0.02. The ionized helium appears to share the kinematics of the thermally excited ionized hydrogen gas, so the two species are likely to be well mixed. The electron temperature of the ionized gas in MWC 349A deduced from our observations is 6,300 $\pm$ 600 K.Comment: Accepted for publication in ApJ

Kuiper Binary Object Formation

It has been observed that binary Kuiper Belt Objects (KBOs) exist contrary to theoretical expectations. Their creation presents problems to most current models. However, the inclusion of a third body (for example, one of the outer planets) may provide the conditions necessary for the formation of these objects. The presence of a third massive body not only helps to clear the primordial Kuiper Belt but can also result in long lived binary Kuiper belt objects. The gravitational interaction between the KBOs and the third body causes one of four effects; scattering into the Oort cloud, collisions with the growing protoplanets, formation of binary pairs, or creation of a single Kuiper belt object. Additionally, the initial location of the progenitors of the Kuiper belt objects also has a significant effect on binary formation

OMA 2011: orthology inference among 1000 complete genomes

OMA (Orthologous MAtrix) is a database that identifies orthologs among publicly available, complete genomes. Initiated in 2004, the project is at its 11th release. It now includes 1000 genomes, making it one of the largest resources of its kind. Here, we describe recent developments in terms of species covered; the algorithmic pipeline—in particular regarding the treatment of alternative splicing, and new features of the web (OMA Browser) and programming interface (SOAP API). In the second part, we review the various representations provided by OMA and their typical applications. The database is publicly accessible at http://omabrowser.org