1,519 research outputs found
On the Derivative Imbalance and Ambiguity of Functions
In 2007, Carlet and Ding introduced two parameters, denoted by and
, quantifying respectively the balancedness of general functions
between finite Abelian groups and the (global) balancedness of their
derivatives , (providing an
indicator of the nonlinearity of the functions). These authors studied the
properties and cryptographic significance of these two measures. They provided
for S-boxes inequalities relating the nonlinearity to ,
and obtained in particular an upper bound on the nonlinearity which unifies
Sidelnikov-Chabaud-Vaudenay's bound and the covering radius bound. At the
Workshop WCC 2009 and in its postproceedings in 2011, a further study of these
parameters was made; in particular, the first parameter was applied to the
functions where is affine, providing more nonlinearity parameters.
In 2010, motivated by the study of Costas arrays, two parameters called
ambiguity and deficiency were introduced by Panario \emph{et al.} for
permutations over finite Abelian groups to measure the injectivity and
surjectivity of the derivatives respectively. These authors also studied some
fundamental properties and cryptographic significance of these two measures.
Further studies followed without that the second pair of parameters be compared
to the first one.
In the present paper, we observe that ambiguity is the same parameter as
, up to additive and multiplicative constants (i.e. up to rescaling). We
make the necessary work of comparison and unification of the results on ,
respectively on ambiguity, which have been obtained in the five papers devoted
to these parameters. We generalize some known results to any Abelian groups and
we more importantly derive many new results on these parameters
Kolwezi : l'espace habité et ses problèmes dans le premier centre minier du Zaïre
Ville jeune, Kolwezi fut créée en 1937 sur de très riches gisements de cuivre et de cobalt, et reste le premier centre industriel et minier du Zaïre. La ville moyenne de l'époque coloniale, bien planifiée et équipée, opposait les quartiers de cadres européens aux quartiers populaires africains (camps de la Société minière et cité "indigène"), selon une structure polynucléaire. Après un essor démographique et spatial impressionnant, Kolwezi est aujourd'hui une ville importante où les quartiers anciens sont pris dans la marée de l'autoconstruction qui envahit jusqu'aux concessions minières. Une part croissante de l'espace habité échappe à la GECAMINES, jadis "propriétaire" de la ville, et qui envisage de déplacer celle-ci pour exploiter de nouveaux gisements. Tout cela rend très nécessaire l'élaboration d'un schéma d'aménagement global de la ville de Kolwezi. (Résumé d'auteur
Scalar Meson Spectroscopy with Lattice Staggered Fermions
With sufficiently light up and down quarks the isovector () and
isosinglet () scalar meson propagators are dominated at large distance by
two-meson states. In the staggered fermion formulation of lattice quantum
chromodynamics, taste-symmetry breaking causes a proliferation of two-meson
states that further complicates the analysis of these channels. Many of them
are unphysical artifacts of the lattice approximation. They are expected to
disappear in the continuum limit. The staggered-fermion fourth-root procedure
has its purported counterpart in rooted staggered chiral perturbation theory
(rSXPT). Fortunately, the rooted theory provides a strict framework that
permits the analysis of scalar meson correlators in terms of only a small
number of low energy couplings. Thus the analysis of the point-to-point scalar
meson correlators in this context gives a useful consistency check of the
fourth-root procedure and its proposed chiral realization. Through numerical
simulation we have measured correlators for both the and channels
in the ``Asqtad'' improved staggered fermion formulation in a lattice ensemble
with lattice spacing fm. We analyze those correlators in the context
of rSXPT and obtain values of the low energy chiral couplings that are
reasonably consistent with previous determinations.Comment: 23 pp., 3 figs., submitted to Phys. Rev.
One at a time, live tracking of NGF axonal transport using quantum dots
Retrograde axonal transport of nerve growth factor (NGF) signals is critical for the survival, differentiation, and maintenance of peripheral sympathetic and sensory neurons and basal forebrain cholinergic neurons. However, the mechanisms by which the NGF signal is propagated from the axon terminal to the cell body are yet to be fully elucidated. To gain insight into the mechanisms, we used quantum dot-labeled NGF (QD-NGF) to track the movement of NGF in real time in compartmentalized culture of rat dorsal root ganglion (DRG) neurons. Our studies showed that active transport of NGF within the axons was characterized by rapid, unidirectional movements interrupted by frequent pauses. Almost all movements were retrograde, but short-distance anterograde movements were occasionally observed. Surprisingly, quantitative analysis at the single molecule level demonstrated that the majority of NGF-containing endosomes contained only a single NGF dimer. Electron microscopic analysis of axonal vesicles carrying QD-NGF confirmed this finding. The majority of QD-NGF was found to localize in vesicles 50–150 nm in diameter with a single lumen and no visible intralumenal membranous components. Our findings point to the possibility that a single NGF dimer is sufficient to sustain signaling during retrograde axonal transport to the cell body
AMiBA: Broadband Heterodyne CMB Interferometry
The Y. T. Lee Array for Microwave Background (AMiBA) has reported the first
science results on the detection of galaxy clusters via the Sunyaev Zel'dovich
effect. The science objectives required small reflectors in order to sample
large scale structures (20') while interferometry provided modest resolutions
(2'). With these constraints, we designed for the best sensitivity by utilizing
the maximum possible continuum bandwidth matched to the atmospheric window at
86-102GHz, with dual polarizations. A novel wide-band analog correlator was
designed that is easily expandable for more interferometer elements. MMIC
technology was used throughout as much as possible in order to miniaturize the
components and to enhance mass production. These designs will find application
in other upcoming astronomy projects. AMiBA is now in operations since 2006,
and we are in the process to expand the array from 7 to 13 elements.Comment: 10 pages, 6 figures, ApJ in press; a version with high resolution
figures available at
http://www.asiaa.sinica.edu.tw/~keiichi/upfiles/AMiBA7/mtc_highreso.pd
The physics of galactic winds driven by active galactic nuclei
Active galactic nuclei (AGN) drive fast winds in the interstellar medium of
their host galaxies. It is commonly assumed that the high ambient densities and
intense radiation fields in galactic nuclei imply short cooling times, thus
making the outflows momentum-conserving. We show that cooling of high-velocity,
shocked winds in AGN is in fact inefficient in a wide range of circumstances,
including conditions relevant to ultra-luminous infrared galaxies (ULIRGs),
resulting in energy-conserving outflows. We further show that fast
energy-conserving outflows can tolerate a large amount of mixing with cooler
gas before radiative losses become important. For winds with initial velocity
v_in>~10,000 km s^-1, as observed in ultra-violet and X-ray absorption, the
shocked wind develops a two-temperature structure. While most of the thermal
pressure support is provided by the protons, the cooling processes operate
directly only on the electrons. This significantly slows down inverse Compton
cooling, while free free cooling is negligible. Slower winds with v_in~1,000 km
s^-1, such as may be driven by radiation pressure on dust, can also experience
energy-conserving phases but under more restrictive conditions. During the
energy-conserving phase, the momentum flux of an outflow is boosted by a factor
~v_in/2v_s by work done by the hot post-shock gas, where v_s is the velocity of
the swept-up material. Energy-conserving outflows driven by fast AGN winds
(v_in~0.1c) may therefore explain the momentum fluxes Pdot>>L_AGN/c of
galaxy-scale outflows recently measured in luminous quasars and ULIRGs. Shocked
wind bubbles expanding normal to galactic disks may also explain the
large-scale bipolar structures observed in some systems, including around the
Galactic Center, and can produce significant radio, X-ray, and gamma-ray
emission. [Abridged]Comment: 20 pages, 8 figures. MNRAS, in pres
Ultrasonic partial glossectomy
This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens
Modelling and simulating change in reforesting mountain landscapes using a social-ecological framework
Natural reforestation of European mountain landscapes raises major environmental and societal issues. With local stakeholders in the Pyrenees National Park area (France), we studied agricultural landscape colonisation by ash (Fraxinus excelsior) to enlighten its impacts on biodiversity and other landscape functions of importance for the valley socio-economics. The study comprised an integrated assessment of land-use and land-cover change (LUCC) since the 1950s, and a scenario analysis of alternative future policy. We combined knowledge and methods from landscape ecology, land change and agricultural sciences, and a set of coordinated field studies to capture interactions and feedback in the local landscape/land-use system. Our results elicited the hierarchically-nested relationships between social and ecological processes. Agricultural change played a preeminent role in the spatial and temporal patterns of LUCC. Landscape colonisation by ash at the parcel level of organisation was merely controlled by grassland management, and in fact depended on the farmer's land management at the whole-farm level. LUCC patterns at the landscape level depended to a great extent on interactions between farm household behaviours and the spatial arrangement of landholdings within the landscape mosaic. Our results stressed the need to represent the local SES function at a fine scale to adequately capture scenarios of change in landscape functions. These findings orientated our modelling choices in the building an agent-based model for LUCC simulation (SMASH - Spatialized Multi-Agent System of landscape colonization by ASH). We discuss our method and results with reference to topical issues in interdisciplinary research into the sustainability of multifunctional landscapes
Intraneuronal Aβ detection in 5xFAD mice by a new Aβ-specific antibody
<p>Abstract</p> <p>Background</p> <p>The form(s) of amyloid-β peptide (Aβ) associated with the pathology characteristic of Alzheimer's disease (AD) remains unclear. In particular, the neurotoxicity of intraneuronal Aβ accumulation is an issue of considerable controversy; even the existence of Aβ deposits within neurons has recently been challenged by Winton and co-workers. These authors purport that it is actually intraneuronal APP that is being detected by antibodies thought to be specific for Aβ. To further address this issue, an anti-Aβ antibody was developed (MOAB-2) that specifically detects Aβ, but not APP. This antibody allows for the further evaluation of the early accumulation of intraneuronal Aβ in transgenic mice with increased levels of human Aβ in 5xFAD and 3xTg mice.</p> <p>Results</p> <p>MOAB-2 (mouse IgG<sub>2b</sub>) is a pan-specific, high-titer antibody to Aβ residues 1-4 as demonstrated by biochemical and immunohistochemical analyses (IHC), particularly compared to 6E10 (a commonly used commercial antibody to Aβ residues 3-8). MOAB-2 did not detect APP or APP-CTFs in cell culture media/lysates (HEK-APP<sub>Swe </sub>or HEK-APP<sub>Swe</sub>/BACE1) or in brain homogenates from transgenic mice expressing 5 familial AD (FAD) mutation (5xFAD mice). Using IHC on 5xFAD brain tissue, MOAB-2 immunoreactivity co-localized with C-terminal antibodies specific for Aβ40 and Aβ42. MOAB-2 did not co-localize with either N- or C-terminal antibodies to APP. In addition, no MOAB-2-immunreactivity was observed in the brains of 5xFAD/BACE<sup>-/- </sup>mice, although significant amounts of APP were detected by N- and C-terminal antibodies to APP, as well as by 6E10. In both 5xFAD and 3xTg mouse brain tissue, MOAB-2 co-localized with cathepsin-D, a marker for acidic organelles, further evidence for intraneuronal Aβ, distinct from Aβ associated with the cell membrane. MOAB-2 demonstrated strong intraneuronal and extra-cellular immunoreactivity in 5xFAD and 3xTg mouse brain tissues.</p> <p>Conclusions</p> <p>Both intraneuronal Aβ accumulation and extracellular Aβ deposition was demonstrated in 5xFAD mice and 3xTg mice with MOAB-2, an antibody that will help differentiate intracellular Aβ from APP. However, further investigation is required to determine whether a molecular mechanism links the presence of intraneuronal Aβ with neurotoxicity. As well, understanding the relevance of these observations to human AD patients is critical.</p
Offspring sex and risk of epithelial ovarian cancer: a multinational pooled analysis of 12 case-control studies
While childbearing protects against risk of epithelial ovarian cancer (EOC), few studies have explored the impact on maternal EOC risk of sex of offspring, which may affect the maternal environment during pregnancy. We performed a pooled analysis among parous participants from 12 case–controls studies comprising 6872 EOC patients and 9101 controls. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using multivariable logistic regression for case–control associations and polytomous logistic regression for histotype-specific associations, all adjusted for potential confounders. In general, no associations were found between offspring sex and EOC risk. However, compared to bearing only female offspring, bearing one or more male offspring was associated with increased risk of mucinous EOC (OR = 1.45; 95% CI = 1.01-2.07), which appeared to be limited to women reporting menarche before age 13 compared to later menarche (OR = 1.71 vs 0.99; P-interaction = 0.02). Bearing increasing numbers of male offspring was associated with greater risks of mucinous tumors (OR = 1.31, 1.84, 2.31, for 1, 2 and 3 or more male offspring, respectively; trend-p = 0.005). Stratifying by hormonally-associated conditions suggested that compared to bearing all female offspring, bearing a male offspring was associated with lower risk of endometrioid cancer among women with a history of adult acne, hirsutism, or polycystic ovary syndrome (OR = 0.49, 95% CI = 0.28-0.83) but with higher risk among women without any of those conditions (OR = 1.64 95% CI = 1.14–2.34; P-interaction = 0.003). Offspring sex influences the childbearing-EOC risk relationship for specific histotypes and conditions. These findings support the differing etiologic origins of EOC histotypes and highlight the importance of EOC histotype-specific epidemiologic studies. These findings also suggest the need to better understand how pregnancy affects EOC ris
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