15 research outputs found
Initial Optical Results for the ChaMPlane Survey
We provide a brief description of the optical survey being conducted under
the NOAO Long Term Surveys program in support of the Chandra Multiwavelength
Plane (ChaMPlane) Survey (see paper by Grindlay et al. in this Volume). A
representative photometry result is shown, along with spectroscopic followup.Comment: 1 page, 2 figures (in 3 files). Astronomische Nachrichten, in press
(Feb 2003). Proceedings of "X-ray Surveys, in the Light of New
Observatories", 4-6 September, Santander, Spai
Chandra Multi-wavelength Plane (ChaMPlane) Survey: Design and Initial Results
The Chandra Multiwavength Plane (ChaMPlane) Survey of the galactic plane
incorporates serendipitous sources from selected Chandra pointings in or near
the galactic plane (b 20 ksec; lack of bright diffuse or point
sources) to measure or constrain the luminosity function of low-luminosity
accretion sources in the Galaxy. The primary goal is to detect and identify
accreting white dwarfs (cataclysmic variables, with space density still
uncertain by a factor of >10-100), neutron stars and black holes (quiescent low
mass X-ray binaries) to constrain their space densities and thus origin and
evolution. Secondary objectives are to identify Be stars in high mass X-ray
binaries and constrain their space densities, and to survey the H-R diagram for
stellar coronal sources. A parallel optical imaging under the NOAO Long Term
Survey program provides deep optical images using the Mosaic imager on the CTIO
and KPNO 4-m telescopes. The 36arcmin X 36arcmin optical images (Halpha, R, V
and I) cover ~5X the area of each enclosed Chandra ACIS FOV, providing an
extended survey of emission line objects for comparison with Chandra.
Spectroscopic followup of optical counterparts is then conducted, thus far with
WIYN and Magellan. The X-ray preliminary results from both the Chandra and
optical surveys will be presented, including logN-logS vs. galactic position
(l,b) and optical idenifications.Comment: 4 pages, 7 figures (in 8 files), Astronomishe Nachrichten, in press
(Feb 2003). Proceedings of "X-ray Surveys, in the Light of New
Observatories", 4-6 September, Santander, Spain. Higher resolution figures
available at:
http://hea-www.harvard.edu/ChaMPlane/papers/champlane-santander.pd
Physical Conditions in Shocked Interstellar Gas Interacting with the Supernova Remnant IC 443
We present the results of a detailed investigation into the physical
conditions in interstellar material interacting with the supernova remnant IC
443. Our analysis is based on a comprehensive examination of high-resolution
far-ultraviolet spectra obtained with the Space Telescope Imaging Spectrograph
onboard the Hubble Space Telescope of two stars behind IC 443. One of our
targets (HD 43582) probes gas along the entire line of sight through the
supernova remnant, while the other (HD 254755) samples material located ahead
of the primary supernova shock front. We identify low velocity quiescent gas in
both directions and find that the densities and temperatures in these
components are typical of diffuse atomic and molecular clouds. Numerous high
velocity components are observed in the absorption profiles of neutral and
singly-ionized atomic species toward HD 43582. These components exhibit a
combination of greatly enhanced thermal pressures and significantly reduced
dust-grain depletions. We interpret this material as cooling gas in a
recombination zone far downstream from shocks driven into neutral gas clumps.
The pressures derived for a group of ionized gas components at high positive
velocity toward HD 43582 are lower than those of the other shocked components,
pointing to pressure inhomogeneities across the remnant. A strong very high
velocity component near -620 km/s is seen in the absorption profiles of
highly-ionized species toward HD 43582. The velocity of this material is
consistent with the range of shock velocities implied by observations of soft
thermal X-ray emission from IC 443. Moderately high-velocity gas toward HD
254755 may represent shocked material from a separate foreground supernova
remnant.Comment: 88 pages, 27 figures, accepted for publication in Ap
Genome-wide Analyses Identify KIF5A as a Novel ALS Gene
To identify novel genes associated with ALS, we undertook two lines of investigation. We carried out a genome-wide association study comparing 20,806 ALS cases and 59,804 controls. Independently, we performed a rare variant burden analysis comparing 1,138 index familial ALS cases and 19,494 controls. Through both approaches, we identified kinesin family member 5A (KIF5A) as a novel gene associated with ALS. Interestingly, mutations predominantly in the N-terminal motor domain of KIF5A are causative for two neurodegenerative diseases: hereditary spastic paraplegia (SPG10) and Charcot-Marie-Tooth type 2 (CMT2). In contrast, ALS-associated mutations are primarily located at the C-terminal cargo-binding tail domain and patients harboring loss-of-function mutations displayed an extended survival relative to typical ALS cases. Taken together, these results broaden the phenotype spectrum resulting from mutations in KIF5A and strengthen the role of cytoskeletal defects in the pathogenesis of ALS.Peer reviewe
Finishing the euchromatic sequence of the human genome
The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead
A Capstone Design Project for Teaching Cybersecurity to Non-technical Users
This paper presents a multi-year undergraduate computing capstone project that holistically contributes to the development of cybersecurity knowledge and skills in non-computing high school and college students. We describe the student-built Vulnerable Web Server application, which is a system that packages instructional materials and pre-built virtual machines to provide lessons on cybersecurity to non-technical students. The Vulnerable Web Server learning materials have been piloted at several high schools and are now integrated into multiple security lessons in an intermediate, general education information technology course at the United States Military Academy. Our paper interweaves a description of the Vulnerable Web Server materials with the senior capstone design process that allowed it to be built by undergraduate information technology and computer science students, resulting in a valuable capstone learning experience. Throughout the paper, a call is made for greater emphasis on educating the non-technical user
Pan genome of the phytoplankton Emiliania underpins its global distribution
Coccolithophores have influenced the global climate for over 200
million years1. These marine phytoplankton can account for 20 per
cent of total carbon fixation in some systems2. They form blooms
that can occupy hundreds of thousands of square kilometres and
are distinguished by their elegantly sculpted calcium carbonate exoskeletons
(coccoliths), rendering themvisible fromspace3.Although
coccolithophores export carbon in the form of organic matter and
calcite to the sea floor, they also release CO2 in the calcification
process. Hence, they have a complex influence on the carbon cycle,
driving either CO2 production or uptake, sequestration and export
to the deep ocean4. Here we report the first haptophyte reference
genome, from the coccolithophore Emiliania huxleyi strain
CCMP1516, and sequences from 13 additional isolates. Our analyses
reveal a pan genome (core genes plus genes distributed variably
between strains) probably supported by an atypical complement
of repetitive sequence in the genome. Comparisons across strains
demonstrate thatE. huxleyi, which has long been considered a single
species, harbours extensive genome variability reflected in different
metabolic repertoires. Genome variability within this species
complex seems to underpin its capacity both to thrive in habitats
ranging from the equator to the subarctic and to form large-scale
episodic blooms under a wide variety of environmental conditions