5,484 research outputs found
The Luminosity Function of Galaxies in the Las Campanas Redshift Survey
We present the -band luminosity function for a sample of 18678 galaxies,
with average redshift , from the Las Campanas Redshift Survey. The
luminosity function may be fit by a Schechter function with , , and $\phi^* = 0.019 \pm 0.001 \
h^3^{-3}-23.0 \leq M - 5 \log h \leq -17.5b_J \approx 20b_J \approx 20\alpha = -0.7\alpha = -1W_{\lambda} = 5\alphaM^* =
-20.03 \pm 0.03 + 5 \log h\alpha = -0.9 \pm 0.1M^* = -20.22 \pm 0.02 + 5 \log h\alpha = -0.3
\pm 0.1$.
(abridged abstract)Comment: 41 pages, including 13 postscript figures, uses AASTEX v4.0 style
files. Important clarification of R-band definition, plus correction of
luminosity densities and updated references. Main conclusions unchanged.
Final version to appear in Ap
Molecular dissection of the mechanism by which EWS/FLI expression compromises actin cytoskeletal integrity and cell adhesion in Ewing sarcoma.
Ewing sarcoma is the second-most-common bone cancer in children. Driven by an oncogenic chromosomal translocation that results in the expression of an aberrant transcription factor, EWS/FLI, the disease is typically aggressive and micrometastatic upon presentation. Silencing of EWS/FLI in patient-derived tumor cells results in the altered expression of hundreds to thousands of genes and is accompanied by dramatic morphological changes in cytoarchitecture and adhesion. Genes encoding focal adhesion, extracellular matrix, and actin regulatory proteins are dominant targets of EWS/FLI-mediated transcriptional repression. Reexpression of genes encoding just two of these proteins, zyxin and α5 integrin, is sufficient to restore cell adhesion and actin cytoskeletal integrity comparable to what is observed when the EWS/FLI oncogene expression is compromised. Using an orthotopic xenograft model, we show that EWS/FLI-induced repression of α5 integrin and zyxin expression promotes tumor progression by supporting anchorage-independent cell growth. This selective advantage is paired with a tradeoff in which metastatic lung colonization is compromised
Observation of ferromagnetism above 900 K in Cr-GaN and Cr-AlN
We report the observation of ferromagnetism at over 900K in Cr-GaN and Cr-AlN
thin films. The saturation magnetization moments in our best films of Cr-GaN
and Cr-AlN at low temperatures are 0.42 and 0.6 u_B/Cr atom, respectively,
indicating that 14% and 20%, of the Cr atoms, respectively, are magnetically
active. While Cr-AlN is highly resistive, Cr-GaN exhibits thermally activated
conduction that follows the exponential law expected for variable range hopping
between localized states. Hall measurements on a Cr-GaN sample indicate a
mobility of 0.06 cm^2/V.s, which falls in the range characteristic of hopping
conduction, and a free carrier density (1.4E20/cm^3), which is similar in
magnitude to the measured magnetically-active Cr concentration (4.9E19/cm^3). A
large negative magnetoresistance is attributed to scattering from loose spins
associated with non-ferromagnetic impurities. The results indicate that
ferromagnetism in Cr-GaN and Cr-AlN can be attributed to the double exchange
mechanism as a result of hopping between near-midgap substitutional Cr impurity
bands.Comment: 14 pages, 4 figures, submitted to AP
Draining the Swamp: Micro Virtual Machines as Solid Foundation for Language Development
Many of today\u27s programming languages are broken. Poor performance, lack of features and hard-to-reason-about semantics can cost dearly in software maintenance and inefficient execution. The problem is only getting worse with programming languages proliferating and hardware becoming more complicated. An important reason for this brokenness is that much of language design is implementation-driven. The difficulties in implementation and insufficient understanding of concepts bake bad designs into the language itself. Concurrency, architectural details and garbage collection are three fundamental concerns that contribute much to the complexities of implementing managed languages.
We propose the micro virtual machine, a thin abstraction designed specifically to relieve implementers of managed languages of the most fundamental implementation challenges that currently impede good design. The micro virtual machine targets abstractions over memory (garbage collection), architecture (compiler backend), and concurrency. We motivate the micro virtual machine and give an account of the design and initial experience of a concrete instance, which we call Mu, built over a two year period. Our goal is to remove an important barrier to performant and semantically sound managed language design and implementation
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Mulsemedia: State of the art, perspectives, and challenges
Mulsemedia-multiple sensorial media-captures a wide variety of research efforts and applications. This article presents a historic perspective on mulsemedia work and reviews current developments in the area. These take place across the traditional multimedia spectrum-from virtual reality applications to computer games-as well as efforts in the arts, gastronomy, and therapy, to mention a few. We also describe standardization efforts, via the MPEG-V standard, and identify future developments and exciting challenges the community needs to overcome
Olfactory groove meningioma: Discussion of clinical presentation and surgical outcomes following excision via the subcranial approach
Objectives/Hypothesis: To describe surgical outcomes and radiographic features of olfactory groove meningiomas treated by excision through the subcranial approach. Special emphasis is placed on paranasal sinus and orbit involvement. Study Design: Retrospective review of a series of patients. Methods: Nineteen patients underwent excision of olfactory groove meningioma (OGM) via the transglabellar/subcranial approach between December 1995 and November 2009. Nine patients had previously undergone prior resection at outside institutions, and four had prior radiotherapy in addition to a prior excision. Transglabellar/subcranial surgical approach to the anterior skull base was performed. Results: Tumor histology included three World Health Organization (WHO) grade III lesions, one WHO grade II lesion, and 15 WHO grade I lesions. Fourteen patients had evidence of extension into the paranasal sinuses, with the ethmoid sinus being most commonly involved. KaplanâMeier estimates of mean overall and diseaseâfree survival were 121.45 months and 93.03 months, respectively. The mean followâup interval was 41.0 months, and at the time of data analysis three patients had recurrent tumors. Seven (36.8%) patients experienced a major complication in the perioperative period; there were no perioperative mortalities. Orbit invasion was observed in four patients, with optic nerve impingement in 11 patients. Of these, three patients had longâterm diplopia. No patients experienced worsening of preoperative visual acuity. Conclusions: Olfactory groove meningiomas demonstrate a propensity to spread into the paranasal sinuses, particularly in recurrent cases. Given a tendency for infiltrative recurrence along the skull base, this disease represents an important area of collaboration between neurosurgery and otolaryngology. The subcranial approach offers excellent surgical access for excision, particularly for recurrences that involve the paranasal sinuses and optic apparatus.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87044/1/22174_ftp.pd
Loose Groups of Galaxies in the Las Campanas Redshift Survey
A ``friends-of-friends'' percolation algorithm has been used to extract a
catalogue of dn/n = 80 density enhancements (groups) from the six slices of the
Las Campanas Redshift Survey (LCRS). The full catalogue contains 1495 groups
and includes 35% of the LCRS galaxy sample. A clean sample of 394 groups has
been derived by culling groups from the full sample which either are too close
to a slice edge, have a crossing time greater than a Hubble time, have a
corrected velocity dispersion of zero, or contain a 55-arcsec ``orphan'' (a
galaxy with a mock redshift which was excluded from the original LCRS redshift
catalogue due to its proximity to another galaxy -- i.e., within 55 arcsec).
Median properties derived from the clean sample include: line-of-sight velocity
dispersion sigma_los = 164km/s, crossing time t_cr = 0.10/H_0, harmonic radius
R_h = 0.58/h Mpc, pairwise separation R_p = 0.64/h Mpc, virial mass M_vir =
(1.90x10^13)/h M_sun, total group R-band luminosity L_tot = (1.30x10^11)/h^2
L_sun, and R-band mass-to-light ratio M/L = 171h M_sun/L_sun; the median number
of observed members in a group is 3.Comment: 32 pages of text, 27 figures, 7 tables. Figures 1, 4, 6, 7, and 8 are
in gif format. Tables 1 and 3 are in plain ASCII format (in paper source) and
are also available at http://www-sdss.fnal.gov:8000/~dtucker/LCLG . Accepted
for publication in the September 2000 issue of ApJ
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