6,716 research outputs found
A multi-material transport problem and its convex relaxation via rectifiable -currents
In this paper we study a variant of the branched transportation problem, that
we call multi-material transport problem. This is a transportation problem,
where distinct commodities are transported simultaneously along a network. The
cost of the transportation depends on the network used to move the masses, as
it is common in models studied in branched transportation. The main novelty is
that in our model the cost per unit length of the network does not depend only
on the total flow, but on the actual quantity of each commodity. This allows to
take into account different interactions between the transported goods. We
propose an Eulerian formulation of the discrete problem, describing the flow of
each commodity through every point of the network. We provide minimal
assumptions on the cost, under which existence of solutions can be proved.
Moreover, we prove that, under mild additional assumptions, the problem can be
rephrased as a mass minimization problem in a class of rectifiable currents
with coefficients in a group, allowing to introduce a notion of calibration.
The latter result is new even in the well studied framework of the
"single-material" branched transportation.Comment: Accepted: SIAM J. Math. Ana
GALEX measurements of the Big Blue Bump as a tool to study bolometric corrections in AGNs
Active Galactic Nuclei emit over the entire electromagnetic spectrum with the
peak of the accretion disk emission in the far-UV, a wavelength range
historically difficult to investigate. We use here the GALEX (Galaxy Evolution
Explorer) Near-UV and Far-UV measurements (complemented with optical data from
Sloan Digital Sky Survey (SDSS) and XMM-Newton X-ray spectra) of a sample of 83
X-ray selected type 1 AGN extracted from the XMM-Newton Bright Serendipitous
Survey to study their spectral energy distribution (SED) in the optical, Near
and Far-UV and X-ray energy bands. We have constrained the luminosity of the
accretion disk emission component and calculated the hard X-ray bolometric
corrections for a significant sample of AGN spanning a large range in
properties (z, L(x)).Comment: 2 pages, 2 figures, To appear in refereed Proceedings of "X-ray
Astronomy 2009: Present Status, Multi-Wavelength Approach and Future
Perspectives", Bologna, Italy, September 7-11, 2009, AIP, eds. A. Comastri,
M. Cappi, and L. Angelin
Botulinum toxin therapy: functional silencing of salivary disorders.
Botulinum toxin (BTX) is a neurotoxic protein produced by Clostridium botulinum, an anaerobic bacterium. BTX therapy is a safe and
effective treatment when used for functional silencing of the salivary glands in disorders such as sialoceles and salivary fistulas that may
have a post-traumatic or post-operative origin. BTX injections can be considered in sialoceles and salivary fistulas after the failure of or
together with conservative treatments (e.g. antibiotics, pressure dressings, or serial aspirations). BTX treatment has a promising role in
chronic sialadenitis. BTX therapy is highly successful in the treatment of gustatory sweating (Frey\u2019s syndrome), and could be considered
the gold standard treatment for this neurological disorder
Voices of Women in the Field--The Good, The Bad, and The Ugly
Editor\u27s note: One of the frequently mentioned challenges noted by principals is finding adequate time to complete all the tasks that present themselves. Writing for journals is not on the priority list of most principals. Although Dr. Marchese agreed to write an article, in fact the real world of the principalship took precedence over the writing task. This article, then, is the result of a telephone conversation, lunch and a writing collaboration -my fingers, her words. (Grady
Enhancing the Understanding of Anatomy Through the Coloration and Plastination of Anatomical Specimens
Articlehttp://deepblue.lib.umich.edu/bitstream/2027.42/96980/1/UMURF-Issue05_2008-AMarchese.pd
Voices of Women in the Field--The Good, The Bad, and The Ugly
Editor\u27s note: One of the frequently mentioned challenges noted by principals is finding adequate time to complete all the tasks that present themselves. Writing for journals is not on the priority list of most principals. Although Dr. Marchese agreed to write an article, in fact the real world of the principalship took precedence over the writing task. This article, then, is the result of a telephone conversation, lunch and a writing collaboration -my fingers, her words. (Grady
Black-hole masses of type 1 AGN in the XMM-Newton bright serendipitous survey
We derive masses of the central super-massive black hole (SMBH) and accretion
rates for 154 type1 AGN belonging to a well-defined X-ray-selected sample, the
XMM-Newton Serendipitous Sample (XBS). To this end, we use the most recent
"single-epoch" relations, based on Hbeta and MgII2798A emission lines, to
derive the SMBH masses. We then use the bolometric luminosities, computed on
the basis of an SED-fitting procedure, to calculate the accretion rates, both
absolute and normalized to the Eddington luminosity (Eddington ratio). The
selected AGNs cover a range of masses from 10^7 to 10^10 Msun with a peak
around 8x10^8 Msun and a range of accretion rates from 0.01 to ~50 Msun/year
(assuming an efficiency of 0.1), with a peak at ~1 Msun/year. The values of
Eddington ratio range from 0.001 to ~0.5 and peak at 0.1.Comment: 14 pages, 11 figures. Accepted for publication in Astronomy &
Astrophysic
The role of gyrA , gyrB , and dnaA functions in bacterial conjugation
The role of DNA gyrase in F'lac plasmid conjugation was studied using Escherichia coli gyrA43 (Ts), gyrB41(Ts), and dnaA46(Ts) thermosensitive mutants as donor or recipient organisms, and a rifampicin or nalidixic acid-resistant J-53 strain in the presence or absence of nalidixic acid. Mating experiments were also performed employing Hfr derivatives of the thermosensitive strains. Conjugation was carried out in broth for 60 min using a standard method at permissive and non-permissive (32 and 43 °C) temperatures, with or without drugs. At 32 °C, nalidixic acid reduced the number of transconjugants by about 97 % in comparison to the control, while at 43 °C, the drug inhibited F'lac transfer by about 98 % from dnaA46(Ts) mutant and by about 6.5 % from gyrA43(Ts) and 15 % from gyrB41(Ts) hosts. Using the temperature-sensitive mutants as recipient strains, the transconjugants found were approximately the same under all conditions. The number of transconjugants did not change significantly when nalidixic acid-resistant strains were used as donor or recipient strains. Lastly, nalidixic acid reduced the number of transconjugants from Hfr selected in the above mutants under all experimental conditions. These findings suggest that F'lac transfer does not involve DNA gyrase activity
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