931 research outputs found
BAYESIAN ANALYSIS OF ADAPTIVE ONE-FACTOR-AT-A-TIME EXPERIMENTATION
ABSTRACT This paper considers the problem of achieving improvement
Glioma Expansion in Collagen I Matrices: Analyzing Collagen Concentration-Dependent Growth and Motility Patterns
Kaufman, L. J., C. P. Brangwynne, K. E. Kasza, E. Filippidi, V. D. Gordon, T. S. Deisboeck, and D. A. Weitz. “Glioma Expansion in Collagen I Matrices: Analyzing Collagen Concentration-Dependent Growth and Motility Patterns.” Biophysical Journal 89, no. 1 (July 2005): 635–50. doi:10.1529/biophysj.105.061994. -- C. P. Brangwynne, K. E. Kasza, and E. Filippidi, are with the Division of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts -- L. J. Kaufman, V. D. Gordon (currently with UT Austin), and D. A.Weitz are with the Department of Physics, Harvard University, Cambridge, Massachusetts -- T. S. Deisboeck is with the Molecular Neuro-Oncology Laboratory, Massachusetts General Hospital, Charlestown, Massachusetts and {Complex Biosystems Modeling Laboratory, Harvard-MIT (HST) Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts -- L. J. Kaufman is with the Center for Imaging and Mesoscale Structures, Harvard University, Cambridge, Massachusetts; andWe study the growth and invasion of glioblastoma multiforme (GBM) in three-dimensional collagen I matrices of
varying collagen concentration. Phase-contrast microscopy studies of the entire GBM system show that invasiveness at early
times is limited by available collagen fibers. At early times, high collagen concentration correlates with more effective invasion.
Conversely, high collagen concentration correlates with inhibition in the growth of the central portion of GBM, the multicellular
tumor spheroid. Analysis of confocal reflectance images of the collagen matrices quantifies how the collagen matrices differ as
a function of concentration. Studying invasion on the length scale of individual invading cells with a combination of confocal and
coherent anti-Stokes Raman scattering microscopy reveals that the invasive GBM cells rely heavily on cell-matrix interactions
during invasion and remodeling.Chemistr
Passive remote sensing of tropospheric aerosol and atmospheric correction for the aerosol effect
The launch of ADEOS in August 1996 with POLDER, TOMS, and OCTS instruments on board and the future launch of EOS-AM 1 in mid-1998 with MODIS and MISR instruments on board start a new era in remote sensing of aerosol as part of a new remote sensing of the whole Earth system (see a list of the acronyms in the Notation section of the paper). These platforms will be followed by other international platforms with unique aerosol sensing capability, some still in this century (e.g., ENVISAT in 1999). These international spaceborne multispectral, multiangular, and polarization measurements, combined for the first time with international automatic, routine monitoring of aerosol from the ground, are expected to form a quantum leap in our ability to observe the highly variable global aerosol. This new capability is contrasted with present single-channel techniques for AVHRR, Meteosat, and GOES that although poorly calibrated and poorly characterized already generated important aerosol global maps and regional transport assessments. The new data will improve significantly atmospheric corrections for the aerosol effect on remote sensing of the oceans and be used to generate first real-time atmospheric corrections over the land. This special issue summarizes the science behind this change in remote sensing, and the sensitivity studies and applications of the new algorithms to data from present satellite and aircraft instruments. Background information and a summary of a critical discussion that took place in a workshop devoted to this topic is given in this introductory paper. In the discussion it was concluded that the anticipated remote sensing of aerosol simultaneously from several space platforms with different observation strategies, together with continuous validations around the world, is expected to be of significant importance to test remote sensing approaches to characterize the complex and highly variable aerosol field. So far, we have only partial understanding of the information content and accuracy of the radiative transfer inversion of aerosol information from the satellite data, due to lack of sufficient theoretical analysis and applications to proper field data. This limitation will make the anticipated new data even more interesting and challenging. A main concern is the present inadequate ability to sense aerosol absorption, from space or from the ground. Absorption is a critical parameter for climate studies and atmospheric corrections. Over oceans, main concerns are the effects of white caps and dust on the correction scheme. Future improvement in aerosol retrieval and atmospheric corrections will require better climatology of the aerosol properties and understanding of the effects of mixed composition and shape of the particles. The main ingredient missing in the planned remote sensing of aerosol are spaceborne and ground-based lidar observations of the aerosol profiles
Spitzer Analysis of HII Region Complexes in the Magellanic Clouds: Determining a Suitable Monochromatic Obscured Star Formation Indicator
HII regions are the birth places of stars, and as such they provide the best
measure of current star formation rates (SFRs) in galaxies. The close proximity
of the Magellanic Clouds allows us to probe the nature of these star forming
regions at small spatial scales. We aim to determine the monochromatic IR band
that most accurately traces the bolometric IR flux (TIR), which can then be
used to estimate an obscured SFR. We present the spatial analysis, via
aperture/annulus photometry, of 16 LMC and 16 SMC HII region complexes using
the Spitzer IRAC and MIPS bands. UV rocket data and SHASSA H-alpha data are
also included. We find that nearly all of the LMC and SMC HII region SEDs peak
around 70um, from ~10 to ~400 pc from the central sources. As a result, the
sizes of HII regions as probed by 70um is approximately equal to the sizes as
probed by TIR (about 70 pc in radius); the radial profile of the 70um flux,
normalized by TIR, is constant at all radii (70um ~ 0.45 TIR); the 1-sigma
standard deviation of the 70um fluxes, normalized by TIR, is a lower fraction
of the mean (0.05 to 0.12 out to ~220 pc) than the normalized 8, 24, and 160um
normalized fluxes (0.12 to 0.52); and these results are invariant between the
LMC and SMC. From these results, we argue that 70um is the most suitable IR
band to use as a monochromatic obscured star formation indicator because it
most accurately reproduces the TIR of HII regions in the LMC and SMC and over
large spatial scales. We also explore the general trends of the 8, 24, 70, and
160um bands in the LMC and SMC HII region SEDs, radial surface brightness
profiles, sizes, and normalized (by TIR) radial flux profiles. We derive an
obscured SFR equation that is modified from the literature to use 70um
luminosity, SFR(Mo/yr) = 9.7(0.7)x10^{-44} L(70)(ergs/s), which is applicable
from 10 to 300 pc distance from the center of an HII region.Comment: 21 pages, 12 figures, 4 tables. Will be published in ApJ
The Spitzer Infrared Nearby Galaxies Survey: A High-Resolution Spectroscopy Anthology
High resolution mid-infrared spectra are presented for 155 nuclear and
extranuclear regions from the Spitzer Infrared Nearby Galaxies Survey (SINGS).
The fluxes for nine atomic forbidden and three molecular hydrogen mid-infrared
emission lines are also provided, along with upper limits in key lines for
infrared-faint targets. The SINGS sample shows a wide range in the ratio of
[SIII]18.71um/[SIII]33.48um, but the average ratio of the ensemble indicates a
typical interstellar electron density of 300-400 cm^{-3} on ~23"x15" scales and
500-600 cm^{-3} using ~11"x9" apertures, independent of whether the region
probed is a star-forming nuclear, a star-forming extranuclear, or an AGN
environment. Evidence is provided that variations in gas-phase metallicity play
an important role in driving variations in radiation field hardness, as
indicated by [NeIII]15.56um/[NeII]12.81um, for regions powered by star
formation. Conversely, the radiation hardness for galaxy nuclei powered by
accretion around a massive black hole is independent of metal abundance.
Furthermore, for metal-rich environments AGN are distinguishable from
star-forming regions by significantly larger [NeIII]15.56um/[NeII]12.81um
ratios. Finally, [FeII]25.99um/[NeII]12.81um versus [SiII]34.82um/[SIII]33.48um
also provides an empirical method for discerning AGN from normal star-forming
sources. However, similar to [NeIII]15.56um/[NeII]12.81um, these mid-infrared
line ratios lose their AGN/star-formation diagnostic powers for very low
metallicity star-forming systems with hard radiation fields.Comment: Accepted for publication in Ap
A Study of Heating and Cooling of the ISM in NGC 1097 with Herschel-PACS and Spitzer-IRS
NGC 1097 is a nearby Seyfert 1 galaxy with a bright circumnuclear starburst
ring, a strong large-scale bar and an active nucleus. We present a detailed
study of the spatial variation of the far infrared (FIR) [CII]158um and
[OI]63um lines and mid-infrared H2 emission lines as tracers of gas cooling,
and of the polycyclic aromatic hydrocarbon (PAH) bands as tracers of the
photoelectric heating, using Herschel-PACS, and Spitzer-IRS infrared spectral
maps. We focus on the nucleus and the ring, and two star forming regions (Enuc
N and Enuc S). We estimated a photoelectric gas heating efficiency
([CII]158um+[OI]63um)/PAH in the ring about 50% lower than in Enuc N and S. The
average 11.3/7.7um PAH ratio is also lower in the ring, which may suggest a
larger fraction of ionized PAHs, but no clear correlation with
[CII]158{\mu}m/PAH(5.5 - 14um) is found. PAHs in the ring are responsible for a
factor of two more [CII]158um and [OI]63um emission per unit mass than PAHs in
the Enuc S. SED modeling indicates that at most 25% of the FIR power in the
ring and Enuc S can come from high intensity photodissociation regions (PDRs),
in which case G0 ~ 10^2.3 and nH ~ 10^3.5 cm^-3 in the ring. For these values
of G0 and nH PDR models cannot reproduce the observed H2 emission. Much of the
the H2 emission in the starburst ring could come from warm regions in the
diffuse ISM that are heated by turbulent dissipation or shocks.Comment: 17 pages, 14 figures, 5 tables; accepted for publication in Ap
Assessment of the revised Difficulties in Emotion Regulation Scales among adolescents and adults with severe mental illness
The Difficulties in Emotion Regulation Scale (DERS) comprising 36 items has been widely used across age, gender, psychopathology, language, and culture. Recently several alternative abridged forms have been introduced, namely, the DERS-16 (Bjureberg et al. 2016), the DERS-SF (Kaufman et al. 2016), and the DERS-18 (Victor and Klonsky, 2016), each composed of 16 or 18 items, to provide researchers and clinicians with a shorter measure of emotion dysregulation. However, no study to date has directly compared the psychometrics of these alternative forms. In the present study, using confirmatory factor analysis we first examined the factor structure of the four models of the DERS in two inpatient samples of 636 adolescents in the age-range of 12–17 years (M = 15.33, SD = 1.43), and 1807 adults in the age-range of 18–76 years (M = 34.86, SD = 14.63) with severe mental illness. Next, measurement invariance was tested comparing the two age groups across the four models of DERS. Only the DERS-SF established metric and scalar measurement invariance. Findings suggest that the factor structure of the original and the abridged models of DERS have acceptable fit, however only DERS-SF had equivalence of factor loadings and item intercepts across adolescents and adults
Hyperspectral remote sensing of cyanobacterial pigments as indicators for cell populations and toxins in eutrophic lakes
The growth of mass populations of toxin-producing cyanobacteria is a serious concern for the ecological
status of inland waterbodies and for human and animal health. In this study we examined the performance
of four semi-analytical algorithms for the retrieval of chlorophyll a (Chl a) and phycocyanin (C-PC) from data
acquired by the Compact Airborne Spectrographic Imager-2 (CASI-2) and the Airborne Imaging Spectrometer
for Applications (AISA) Eagle sensor. The retrieval accuracies of the semi-analytical models were
compared to those returned by optimally calibrated empirical band-ratio algorithms. The best-performing
algorithm for the retrieval of Chl a was an empirical band-ratio model based on a quadratic function of the
ratio of re!ectance at 710 and 670 nm (R2=0.832; RMSE=29.8%). However, this model only provided a
marginally better retrieval than the best semi-analytical algorithm. The best-performing model for the
retrieval of C-PC was a semi-analytical nested band-ratio model (R2=0.984; RMSE=3.98 mg m−3). The
concentrations of C-PC retrieved using the semi-analytical model were correlated with cyanobacterial cell
numbers (R2=0.380) and the particulate and total (particulate plus dissolved) pools of microcystins
(R2=0.858 and 0.896 respectively). Importantly, both the empirical and semi-analytical algorithms were
able to retrieve the concentration of C-PC at cyanobacterial cell concentrations below current warning
thresholds for cyanobacteria in waterbodies. This demonstrates the potential of remote sensing to contribute
to early-warning detection and monitoring of cyanobacterial blooms for human health protection at regional
and global scales
A forgotten figure in Siouan and Caddoan linguistics: Samuel Stehman Haldeman.
The Siouan family comprises some twenty languages, historically spoken across a broad swath of the central North American plains and woodlands, as well as in parts of the southeastern United States. In spite of its geographical extent and diversity, and the size and importance of several Siouan-speaking tribes, this family has received relatively little attention in the linguistic literature and many of the individual Siouan languages are severely understudied. This volume aims to make work on Siouan languages more broadly available and to encourage deeper investigation of the myriad typological, theoretical, descriptive, and pedagogical issues they raise.
The 17 chapters in this volume present a broad range of current Siouan research, focusing on various Siouan languages, from a variety of linguistic perspectives: historical-genetic, philological, applied, descriptive, formal/generative, and comparative/typological. The editors' preface summarizes characteristic features of the Siouan family, including head-final and "verb-centered" syntax, a complex system of verbal affixes including applicatives and subject-possessives, head-internal relative clauses, gendered speech markers, stop-systems including ejectives, and a preference for certain prosodic and phonotactic patterns.
The volume is dedicated to the memory of Professor Robert L. Rankin, a towering figure in Siouan linguistics throughout his long career, who passed away in February of 2014
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