431 research outputs found
How is the Reionization Epoch Defined?
We study the effect of a prolonged epoch of reionization on the angular power
spectrum of the Cosmic Microwave Background. Typically reionization studies
assume a sudden phase transition, with the intergalactic gas moving from a
fully neutral to a fully ionized state at a fixed redshift. Such models are at
odds, however, with detailed investigations of reionization, which favor a more
extended transition. We have modified the code CMBFAST to allow the treatment
of more realistic reionization histories and applied it to data obtained from
numerical simulations of reionization. We show that the prompt reionization
assumed by CMBFAST in its original form heavily contaminates any constraint
derived on the reionization redshift. We find, however, that prompt
reionization models give a reasonable estimate of the epoch at which the mean
cosmic ionization fraction was ~50%, and provide a very good measure of the
overall Thomson optical depth. The overall differences in the temperature
(polarization) angular power spectra between prompt and extended models with
equal optical depths are less than 1% (10%).Comment: 5 pages, 3 figures; accepted on MNRA
On Structuring Proof Search for First Order Linear Logic
Full first order linear logic can be presented as an abstract logic
programming language in Miller's system Forum, which yields a sensible
operational interpretation in the 'proof search as computation' paradigm.
However, Forum still has to deal with syntactic details that would normally be
ignored by a reasonable operational semantics. In this respect, Forum improves
on Gentzen systems for linear logic by restricting the language and the form of
inference rules. We further improve on Forum by restricting the class of
formulae allowed, in a system we call G-Forum, which is still equivalent to
full first order linear logic. The only formulae allowed in G-Forum have the
same shape as Forum sequents: the restriction does not diminish expressiveness
and makes G-Forum amenable to proof theoretic analysis. G-Forum consists of two
(big) inference rules, for which we show a cut elimination procedure. This does
not need to appeal to finer detail in formulae and sequents than is provided by
G-Forum, thus successfully testing the internal symmetries of our system.Comment: Author website at http://alessio.guglielmi.name/res
Use of Genetic Algorithms for Contrast and Entropy Optimization in ISAR Autofocusing
Image contrast maximization and entropy minimization are two commonly used techniques for ISAR image autofocusing. When the signal phase history due to the target radial motion has to be approximated with high order polynomial models, classic optimization techniques fail when attempting to either maximize the image contrast or minimize the image entropy. In this paper a solution of this problem is proposed by using genetic algorithms. The performances of the new algorithms that make use of genetic algorithms overcome the problem with previous implementations based on deterministic approaches. Tests on real data of airplanes and ships confirm the insight
Overexpression of glucocorticoid-induced leucine zipper (GILZ) increases susceptibility to imiquimod-induced psoriasis and involves cutaneous activation of TGF-β1
Psoriasis vulgaris is a chronic inflammatory skin disease affecting millions of people. Its pathophysiology is complex and involves a skin compartment with epidermal and immune cells which produce cytokines, e.g. belonging to the IL-23-Th17-cell axis. Glucocorticoids (GCs) are the most common therapeutics used in cutaneous inflammatory disorders and GC-induced leucine zipper (GILZ) has emerged as a mediator of GCs due to its anti-inflammatory actions, theoretically lacking GC side-effects. We evaluated whether GILZ may provide a better therapeutic index in comparison to GCs during the onset and progression of psoriasis by generating and characterizing a mouse model with generalized overexpression of this protein (GILZ-Tg mice) and the imiquimod (IMQ) psoriasis model. Unexpectedly, in GILZ-Tg mice, the severity of IMQ-induced psoriasis-like skin lesions as well as induction of cytokines commonly up-regulated in human psoriasis (Il-17, Il-22, Il-23, Il-6, S100a8/a9, and Stat3) was significantly more pronounced relative to GILZ-Wt mice. The increased susceptibility to IMQ-induced psoriasis of GILZ-Tg mice was significantly associated with skin-specific over-activation of TGF-beta 1-mediated signaling via SMAD2/3. Our findings demonstrate that GILZ may behave as pro-inflammatory protein in certain tissues and that, similar to prolonged GC therapy, GILZ as an alternative treatment for psoriasis may also have adverse effects
A System of Interaction and Structure
This paper introduces a logical system, called BV, which extends
multiplicative linear logic by a non-commutative self-dual logical operator.
This extension is particularly challenging for the sequent calculus, and so far
it is not achieved therein. It becomes very natural in a new formalism, called
the calculus of structures, which is the main contribution of this work.
Structures are formulae submitted to certain equational laws typical of
sequents. The calculus of structures is obtained by generalising the sequent
calculus in such a way that a new top-down symmetry of derivations is observed,
and it employs inference rules that rewrite inside structures at any depth.
These properties, in addition to allow the design of BV, yield a modular proof
of cut elimination.Comment: This is the authoritative version of the article, with readable
pictures, in colour, also available at
. (The published version contains
errors introduced by the editorial processing.) Web site for Deep Inference
and the Calculus of Structures at <http://alessio.guglielmi.name/res/cos
Improving the Environmental Sustainability of Flash Geothermal Power Plants—A Case Study
The sustainability of geothermal energy production is analyzed with reference to a production plant located in a specific area (Monte Amiata, Italy). Four solutions combining a flash power plant with an Organic Rankine Cycle in a hybrid configuration are analyzed in terms of production of electricity, exergy balance and emissions level (CO2, H2S, Hg). The different solutions correspond to increasing environmental performance, and for the most advanced case achieve near-zero emissions (complete reinjection of the natural resource, including incondensable gases). The results show that this can be achieved at the price of a progressive reduction of electrical productivity
Reionization History from Coupled CMB/21cm Line Data
We study CMB secondary anisotropies produced by inhomogeneous reionization by
means of cosmological simulations coupled with the radiative transfer code
CRASH. The reionization history is consistent with the WMAP Thomson optical
depth determination. We find that the signal arising from this process
dominates over the primary CMB component for l > 4000 and reaches a maximum
amplitude of l(l+1)C_l/2\pi ~ 1.6 x 10^{-13} on arcmin scale, i.e. l as large
as several thousands. We then cross-correlate secondary CMB anisotropy maps
with neutral hydrogen 21cm line emission fluctuations obtained from the same
simulations. The two signals are highly anti-correlated on angular scales
corresponding to the typical size of HII regions (including overlapping) at the
21cm map redshift. We show how the CMB/21cm cross-correlation can be used to:
(a) study the nature of the reionization sources, (b) reconstruct the cosmic
reionization history, (c) infer the mean cosmic ionization level at any
redshift. We discuss the feasibility of the proposed experiment with
forthcoming facilities.Comment: 7 pages, 5 figures, MNRAS in pres
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