294 research outputs found
Complex Tissue Regeneration in Mammals Is Associated with Reduced Inflammatory Cytokines and an Influx of T Cells
While mammals tend to repair injuries, other adult vertebrates like salamanders and fish regenerate damaged tissue. One prominent hypothesis offered to explain an inability to regenerate complex tissue in mammals is a bias during healing toward strong adaptive immunity and inflammatory responses. Here we directly test this hypothesis by characterizing part of the immune response during regeneration in spiny mice (Acomys cahirinus and Acomys percivali) vs. fibrotic repair in Mus musculus. By directly quantifying cytokines during tissue healing, we found that fibrotic repair was associated with a greater release of pro-inflammatory cytokines (i.e., IL-6, CCL2, and CXCL1) during acute inflammation in the wound microenvironment. However, reducing inflammation via COX-2 inhibition was not sufficient to reduce fibrosis or induce a regenerative response, suggesting that inflammatory strength does not control how an injury heals. Although regeneration was associated with lower concentrations of many inflammatory markers, we measured a comparatively larger influx of T cells into regenerating ear tissue and detected a local increase in the T cell associated cytokines IL-12 and IL-17 during the proliferative phase of regeneration. Taken together, our data demonstrate that a strong adaptive immune response is not antagonistic to regeneration and that other mechanisms likely explain the distribution of regenerative ability in vertebrates
When Is a Bulge Not a Bulge? Inner Disks Masquerading as Bulges in NGC 2787 and NGC 3945
We present a detailed morphological, photometric, and kinematic analysis of
two barred S0 galaxies with large, luminous inner disks inside their bars. We
show that these structures, in addition to being geometrically disk-like, have
exponential profiles (scale lengths 300--500 pc) distinct from the
central, non-exponential bulges. We also find them to be kinematically
disk-like. The inner disk in NGC 2787 has a luminosity roughly twice that of
the bulge; but in NGC 3945, the inner disk is almost ten times more luminous
than the bulge, which itself is extremely small (half-light radius
100 pc, in a galaxy with an outer ring of radius 14 kpc) and only
5% of the total luminosity -- a bulge/total ratio much more typical of
an Sc galaxy. We estimate that at least 20% of (barred) S0 galaxies may have
similar structures, which means that their bulge/disk ratios may be
significantly overestimated. These inner disks dominate the central light of
their galaxies; they are at least an order of magnitude larger than typical
``nuclear disks'' found in ellipticals and early-type spirals. Consequently,
they must affect the dynamics of the bars in which they reside.Comment: LaTeX, 37 pages, 14 EPS figures. To appear in The Astrophysical
Journal (November 10, 2003 issue). Version with full-resolution figures
available at http://www.iac.es/galeria/erwin/research
Nonequilibrium Fluctuations, Travelling Waves, and Instabilities in Active Membranes
The stability of a flexible fluid membrane containing a distribution of
mobile, active proteins (e.g. proton pumps) is shown to depend on the structure
and functional asymmetry of the proteins. A stable active membrane is in a
nonequilibrium steady state with height fluctuations whose statistical
properties are governed by the protein activity. Disturbances are predicted to
travel as waves at sufficiently long wavelength, with speed set by the normal
velocity of the pumps. The unstable case involves a spontaneous, pump-driven
undulation of the membrane, with clumping of the proteins in regions of high
activity.Comment: 4 two-column pages, two .eps figures included, revtex, uses eps
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Internet: An Overview of Key Technology Policy Issues Affecting Its Use and Growth
This report gives an overview of key technology policy issues of the internet affecting its use and growth
Recommended from our members
Internet: An Overview of Key Technology Policy Issues Affecting Its Use and Growth
This report gives an overview of key technology policy issues of internet affecting its use and growth
C in intense femtosecond laser pulses: nonlinear dipole response and ionization
We study the interaction of strong femtosecond laser pulses with the C
molecule employing time-dependent density functional theory with the ionic
background treated in a jellium approximation. The laser intensities considered
are below the threshold of strong fragmentation but too high for perturbative
treatments such as linear response. The nonlinear response of the model to
excitations by short pulses of frequencies up to 45eV is presented and analyzed
with the help of Kohn-Sham orbital resolved dipole spectra. In femtosecond
laser pulses of 800nm wavelength ionization is found to occur multiphoton-like
rather than via excitation of a ``giant'' resonance.Comment: 14 pages, including 1 table, 5 figure
Efficient pricing of discrete arithmetic Asian options under mean reversion and jumps based on Fourier-cosine expansions
We propose an efficient pricing method for arithmetic Asian options based on Fourier-cosine expansions. In particular, we allow for mean reversion and jumps in the underlying price dynamics. There is an extensive body of empirical evidence in the current literature that points to the existence and prominence of such anomalies in the prices of certain asset classes, such as commodities. Our efficient pricing method is derived for the discretely monitored versions of the European-style arithmetic Asian options. The analytical solutions obtained from our Fourier-cosine expansions are compared to the benchmark fast Fourier transform based pricing for the examination of its accuracy and computational efficienc
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Internet: An Overview of Key Technology Policy Issues Affecting Its Use and Growth
The continued growth of the Internet for personal, government, and business
purposes may be affected by a number of technology policy issues being debated by
Congress. Among them are access to and regulation of broadband (high-speed)
Internet services, computer and Internet security, Internet privacy, the impact of
“spam,” concerns about what children may encounter (such as pornography) when
using the Internet, management of the Internet Domain Name System, and
government information technology management.
This report provides overviews of those issues, plus appendices providing a list
of pending legislation, a list of acronyms, a discussion of legislation passed in
earlier Congresses, and a list of other CRS reports that provide more detail on these
and related topics
BMQ
BMQ: Boston Medical Quarterly was published from 1950-1966 by the Boston University School of Medicine and the Massachusetts Memorial Hospitals
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