273 research outputs found
Highly Variable Extinction and Accretion in the Jet-driving Class I Type Young Star PTF 10nvg (V2492 Cyg, IRAS 20496+4354)
We report extensive new photometry and spectroscopy of the highly variable
young stellar object PTF 10nvg including optical and near-infrared time series
data as well as mid-infrared and millimeter data. Following the previously
reported 2010 rise, during 2011 and 2012 the source underwent additional
episodes of brightening and dimming events including prolonged faint states.
The observed high-amplitude variations are largely consistent with extinction
changes having a 220 day quasi-periodic signal. Spectral evolution includes not
only changes in the spectral slope but correlated variation in the prominence
of TiO/VO/CO bands and atomic line emission, as well as anticorrelated
variation in forbidden line emission which, along with H_2, dominates optical
and infrared spectra at faint epochs. Neutral and singly-ionized atomic species
are likely formed in an accretion flow and/or impact while the origin of
zero-velocity atomic LiI 6707 in emission is unknown. Forbidden lines,
including several rare species, exhibit blueshifted emission profiles and
likely arise from an outflow/jet. Several of these lines are also seen
spatially offset from the continuum source position, presumably in a shocked
region of an extended jet. CARMA maps resolve on larger scales a spatially
extended outflow in mm-wavelength CO. We attribute the observed photometric and
spectroscopic behavior in terms of occultation of the central star as well as
the bright inner disk and the accretion/outflow zones that renders shocked gas
in the inner part of the jet amenable to observation at the faint epochs. We
discuss PTF 10nvg as a source exhibiting both accretion-driven (perhaps
analogous to V1647 Ori) and extinction-driven (perhaps analogous to UX Ori or
GM Cep) high-amplitude variability phenomena.Comment: accepted to AJ - in press (74 pages
Est locus uni cuique suus: City and Status in Horace’s Satires 1.8 and 1.9
This is the published version
Exploring Fitness and Edit Distance of Mutated Python Programs
Genetic Improvement (GI) is the process of using computational search techniques to improve existing software e.g. in terms of execution time, power consumption or correctness. As in most heuristic search algorithms, the search is guided by fitness with GI searching the space of program variants of the original software. The relationship between the program space and fitness is seldom simple and often quite difficult to analyse. This paper makes a preliminary analysis of GI’s fitness distance measure on program repair with three small Python programs. Each program undergoes incremental mutations while the change in fitness as measured by proportion of tests passed is monitored. We conclude that the fitnesses of these programs often does not change with single mutations and we also confirm the inherent discreteness of bug fixing fitness functions. Although our findings cannot be assumed to be general for other software they provide us with interesting directions for further investigation
Explorations, Vol. 4, No. 1
Articles include:
Cover: Old Yarmouth Light, 1960, Cape Forchu, Nova Scotia. By and from the collection of Edgar McKay.
The Borderlands Concept: a new look at U.S.-Canada relations, by Victor Konrad and Lauren McKensey
Fundy Tidal Power Project, by Gregory White
Canadian Poet: Ken Norris
Native American Life and Art: a celebration, November, 1986, by Lee-Ann Konrad
The Montreal Canadiens: a cultural institution, by James J. Herlan
U.S. and Canadian Executives: uses of formal and informal plans in top executive decision-making, by Kent Carter
Our Cover Artist: bits and pieces of one man\u27s Nova Scotia, by Edgar McKay The Canadian-American Center and the Canadian Collection of the Fogler Library, by Alice Stewart
Capitalist Development in the New England-Atlantic Provinces Region, by Robert H. Babcock
Atlantic Canadian Members of Parliament as Representatives, by Howard Cody
The Rower and the Pyramid: a tribute to Joe Walsh, by Edward D. Ives
The Canadian-American Center: exercise in excellence, by Rand Erb
Canadian and Maine Potatoes: a bushel of questions, by George K. Griner, Alan S. Kezis, and James D. Leiby
After 20: the Future of the Canadian-American Center, by Victor Konra
The social affordances of flashpacking: exploring the mobility nexus of travel and communication
The proliferation of digital devices and online social media and networking technologies has altered the backpacking landscape in recent years. Thanks to the ready availability of online communication, travelers are now able to stay in continuous touch with friends, family and other travelers while on the move. This article introduces the practice of ‘flashpacking’ to describe this emerging trend and interrogates the patterns of connection and disconnection that become possible as corporeal travel and social technologies converge. Drawing on the concepts of ‘assemblages’ and ‘affordances’, we outline several aspects of this new sociality: virtual mooring, following, collaborating, and (dis)connecting. The conclusion situates this discussion alongside broader questions about the shifting nature of social life in an increasingly mobile and mediated world and suggests directions for future research at the intersection of tourism and technology
Multi-omics analyses reveal ClpP activators disrupt essential mitochondrial pathways in triple-negative breast cancer
ClpP activators ONC201 and related small molecules (TR compounds, Madera Therapeutics), have demonstrated significant anti-cancer potential in vitro and in vivo studies, including clinical trials for refractory solid tumors. Though progress has been made in identifying specific phenotypic outcomes following ClpP activation, the exact mechanism by which ClpP activation leads to broad anti-cancer activity has yet to be fully elucidated. In this study, we utilized a multi-omics approach to identify the ClpP-dependent proteomic, transcriptomic, and metabolomic changes resulting from ONC201 or the TR compound TR-57 in triple-negative breast cancer cells. Applying mass spectrometry-based methods of proteomics and metabolomics, we identified ∼8,000 proteins and 588 metabolites, respectively. From proteomics data, 113 (ONC201) and 191 (TR-57) proteins significantly increased and 572 (ONC201) and 686 (TR-57) proteins significantly decreased in this study. Gene ontological (GO) analysis revealed strong similarities between proteins up- or downregulated by ONC201 or TR-57 treatment. Notably, this included the downregulation of many mitochondrial processes and proteins, including mitochondrial translation and mitochondrial matrix proteins. We performed a large-scale transcriptomic analysis of WT SUM159 cells, identifying ∼7,700 transcripts (746 and 1,100 significantly increasing, 795 and 1,013 significantly decreasing in ONC201 and TR-57 treated cells, respectively). Less than 21% of these genes were affected by these compounds in ClpP null cells. GO analysis of these data demonstrated additional similarity of response to ONC201 and TR-57, including a decrease in transcripts related to the mitochondrial inner membrane and matrix, cell cycle, and nucleus, and increases in other nuclear transcripts and transcripts related to metal-ion binding. Comparison of response between both compounds demonstrated a highly similar response in all -omics datasets. Analysis of metabolites also revealed significant similarities between ONC201 and TR-57 with increases in α-ketoglutarate and 2-hydroxyglutaric acid and decreased ureidosuccinic acid, L-ascorbic acid, L-serine, and cytidine observed following ClpP activation in TNBC cells. Further analysis identified multiple pathways that were specifically impacted by ClpP activation, including ATF4 activation, heme biosynthesis, and the citrulline/urea cycle. In summary the results of our studies demonstrate that ONC201 and TR-57 induce highly similar and broad effects against multiple mitochondrial processes required for cell proliferation
Velocity dispersion measurements of dwarf galaxies in the Coma cluster - implications for the structure of the fundamental plane
We present intermediate-resolution spectroscopic data for a set of dwarf and
giant galaxies in the Coma Cluster, with -20.6 < M_R < -15.7. The photometric
and kinematic properties of the brighter galaxies can be cast in terms of
parameters which present little scatter with respect to a set of scaling
relations known as the Fundamental Plane. To determine the form of these
fundamental scaling relations at lower luminosities, we have measured velocity
dispersions for a sample comprising 69 galaxies on the border of the dwarf and
giant regime. Combining these data with our photometric survey, we find a tight
correlation of luminosity and velocity dispersion, L \propto \sigma^{2.0},
substantially flatter than the Faber-Jackson relation characterising giant
elliptical galaxies. In addition, the variation of mass-to-light ratio with
velocity dispersion is quite weak in our dwarf sample: M/L \propto
\sigma^{0.2}. Our overall results are consistent with theoretical models
invoking large-scale mass removal and subsequent structural readjustment, e.g.,
as a result of galactic winds.Comment: 15 pages, 11 figures, 1 table. MNRAS, in pres
Improved false negative rate of axillary status using sentinel lymph node biopsy and ultrasound-suspicious lymph node sampling in patients with early breast cancer
Range Expansion Drives Dispersal Evolution In An Equatorial Three-Species Symbiosis
A-09-14International audienceBackground Recurrent climatic oscillations have produced dramatic changes in species distributions. This process has been proposed to be a major evolutionary force, shaping many life history traits of species, and to govern global patterns of biodiversity at different scales. During range expansions selection may favor the evolution of higher dispersal, and symbiotic interactions may be affected. It has been argued that a weakness of climate fluctuation-driven range dynamics at equatorial latitudes has facilitated the persistence there of more specialized species and interactions. However, how much the biology and ecology of species is changed by range dynamics has seldom been investigated, particularly in equatorial regions. Methodology/Principal Findings We studied a three-species symbiosis endemic to coastal equatorial rainforests in Cameroon, where the impact of range dynamics is supposed to be limited, comprised of two species-specific obligate mutualists –an ant-plant and its protective ant– and a species-specific ant parasite of this mutualism. We combined analyses of within-species genetic diversity and of phenotypic variation in a transect at the southern range limit of this ant-plant system. All three species present congruent genetic signatures of recent gradual southward expansion, a result compatible with available regional paleoclimatic data. As predicted, this expansion has been accompanied by the evolution of more dispersive traits in the two ant species. In contrast, we detected no evidence of change in lifetime reproductive strategy in the tree, nor in its investment in food resources provided to its symbiotic ants. Conclusions/Significance Despite the decreasing investment in protective workers and the increasing investment in dispersing females by both the mutualistic and the parasitic ant species, there was no evidence of destabilization of the symbiosis at the colonization front. To our knowledge, we provide here the first evidence at equatorial latitudes that biological traits associated with dispersal are affected by the range expansion dynamics of a set of interacting species
- …