11,139 research outputs found
Late harvest as factor affecting esca and Botryosphaeria dieback prevalence of vineyards in the Alsace region of France
The decline of grapevines due to esca and Botryosphaeria dieback (Bot. dieback) is a serious problem in the Alsace region of France. A survey of 82 vineyards over 8 years showed that among a set of agronomical and cultural variables, esca and Bot. dieback prevalence correlated to the harvest dates, especially late harvest dates for the production of sweet wines. The interpretation of this finding that points to the carbon balance of the vine and its reserves status as possible causation is discussed. Under this hypothesis the data also point to climatic variables as factors in the disease epidemiology, with a lag phase of about one year.
Duality and KPZ in Liouville Quantum Gravity
We present a (mathematically rigorous) probabilistic and geometrical proof of
the KPZ relation between scaling exponents in a Euclidean planar domain D and
in Liouville quantum gravity. It uses the properly regularized quantum area
measure d\mu_\gamma=\epsilon^{\gamma^2/2} e^{\gamma h_\epsilon(z)}dz, where dz
is Lebesgue measure on D, \gamma is a real parameter, 0\leq \gamma <2, and
h_\epsilon(z) denotes the mean value on the circle of radius \epsilon centered
at z of an instance h of the Gaussian free field on D. The proof extends to the
boundary geometry. The singular case \gamma >2 is shown to be related to the
quantum measure d\mu_{\gamma'}, \gamma' < 2, by the fundamental duality
\gamma\gamma'=4.Comment: 4 pages, 1 figur
PMI: A Delta Psi(m) Independent Pharmacological Regulator of Mitophagy
Mitophagy is central to mitochondrial and cellular homeostasis and operates via the PINK1/Parkin pathway targeting mitochondria devoid of membrane potential (ΔΨm) to autophagosomes. Although mitophagy is recognized as a fundamental cellular process, selective pharmacologic modulators of mitophagy are almost nonexistent. We developed a compound that increases the expression and signaling of the autophagic adaptor molecule P62/SQSTM1 and forces mitochondria into autophagy. The compound, P62-mediated mitophagy inducer (PMI), activates mitophagy without recruiting Parkin or collapsing ΔΨm and retains activity in cells devoid of a fully functional PINK1/Parkin pathway. PMI drives mitochondria to a process of quality control without compromising the bio-energetic competence of the whole network while exposing just those organelles to be recycled. Thus, PMI circumvents the toxicity and some of the nonspecific effects associated with the abrupt dissipation of ΔΨm by ionophores routinely used to induce mitophagy and represents a prototype pharmacological tool to investigate the molecular mechanisms of mitophagy
Brian Hears: Online Auditory Processing Using Vectorization Over Channels
The human cochlea includes about 3000 inner hair cells which filter sounds at frequencies between 20 Hz and 20 kHz. This massively parallel frequency analysis is reflected in models of auditory processing, which are often based on banks of filters. However, existing implementations do not exploit this parallelism. Here we propose algorithms to simulate these models by vectorizing computation over frequency channels, which are implemented in “Brian Hears,” a library for the spiking neural network simulator package “Brian.” This approach allows us to use high-level programming languages such as Python, because with vectorized operations, the computational cost of interpretation represents a small fraction of the total cost. This makes it possible to define and simulate complex models in a simple way, while all previous implementations were model-specific. In addition, we show that these algorithms can be naturally parallelized using graphics processing units, yielding substantial speed improvements. We demonstrate these algorithms with several state-of-the-art cochlear models, and show that they compare favorably with existing, less flexible, implementations
Renormalization and Hyperscaling for Self-Avoiding Manifold Models
The renormalizability of the self-avoiding manifold (SAM) Edwards model is
established. We use a new short distance multilocal operator product expansion
(MOPE), which extends methods of local field theories to a large class of
models with non-local singular interactions. This validates the direct
renormalization method introduced before, as well as scaling laws. A new
general hyperscaling relation for the configuration exponent gamma is derived.
Manifolds at the Theta-point, and long range Coulomb interactions are briefly
discussed.Comment: 10 pages + 1 figure, TeX + harvmac & epsf (uuencoded file),
SPhT/93-07
Hybridization gap and anisotropic far-infrared optical conductivity of URu2Si2
We performed far-infrared optical spectroscopy measurements on the heavy
fermion compound URu 2 Si 2 as a function of temperature. The light's
electric-field was applied along the a-axis or the c-axis of the tetragonal
structure. We show that in addition to a pronounced anisotropy, the optical
conductivity exhibits for both axis a partial suppression of spectral weight
around 12 meV and below 30 K. We attribute these observations to a change in
the bandstructure below 30 K. However, since these changes have no noticeable
impact on the entropy nor on the DC transport properties, we suggest that this
is a crossover phenomenon rather than a thermodynamic phase transition.Comment: To be published in Physical Review
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