2,794 research outputs found
Scalable Compression of Deep Neural Networks
Deep neural networks generally involve some layers with mil- lions of
parameters, making them difficult to be deployed and updated on devices with
limited resources such as mobile phones and other smart embedded systems. In
this paper, we propose a scalable representation of the network parameters, so
that different applications can select the most suitable bit rate of the
network based on their own storage constraints. Moreover, when a device needs
to upgrade to a high-rate network, the existing low-rate network can be reused,
and only some incremental data are needed to be downloaded. We first
hierarchically quantize the weights of a pre-trained deep neural network to
enforce weight sharing. Next, we adaptively select the bits assigned to each
layer given the total bit budget. After that, we retrain the network to
fine-tune the quantized centroids. Experimental results show that our method
can achieve scalable compression with graceful degradation in the performance.Comment: 5 pages, 4 figures, ACM Multimedia 201
Charge Renormalization, Effective Interactions, and Thermodynamics of Deionized Colloidal Suspensions
Thermodynamic properties of charge-stabilised colloidal suspensions depend
sensitively on the effective charge of the macroions, which can be
substantially lower than the bare charge in the case of strong
counterion-macroion association. A theory of charge renormalization is
proposed, combining an effective one-component model of charged colloids with a
thermal criterion for distinguishing between free and associated counterions.
The theory predicts, with minimal computational effort, osmotic pressures of
deionized suspensions of highly charged colloids in close agreement with
large-scale simulations of the primitive model.Comment: 15 pages, 7 figure
Poisson-Boltzmann Theory of Charged Colloids: Limits of the Cell Model for Salty Suspensions
Thermodynamic properties of charge-stabilised colloidal suspensions are
commonly modeled by implementing the mean-field Poisson-Boltzmann (PB) theory
within a cell model. This approach models a bulk system by a single macroion,
together with counterions and salt ions, confined to a symmetrically shaped,
electroneutral cell. While easing solution of the nonlinear PB equation, the
cell model neglects microion-induced correlations between macroions, precluding
modeling of macroion ordering phenomena. An alternative approach, avoiding
artificial constraints of cell geometry, maps a macroion-microion mixture onto
a one-component model of pseudo-macroions governed by effective interactions.
In practice, effective-interaction models are usually based on linear screening
approximations, which can accurately describe nonlinear screening only by
incorporating an effective (renormalized) macroion charge. Combining charge
renormalization and linearized PB theories, in both the cell model and an
effective-interaction (cell-free) model, we compute osmotic pressures of highly
charged colloids and monovalent microions over a range of concentrations. By
comparing predictions with primitive model simulation data for salt-free
suspensions, and with predictions of nonlinear PB theory for salty suspensions,
we chart the limits of both the cell model and linear-screening approximations
in modeling bulk thermodynamic properties. Up to moderately strong
electrostatic couplings, the cell model proves accurate in predicting osmotic
pressures of deionized suspensions. With increasing salt concentration,
however, the relative contribution of macroion interactions grows, leading
predictions of the cell and effective-interaction models to deviate. No
evidence is found for a liquid-vapour phase instability driven by monovalent
microions. These results may guide applications of PB theory to soft materials.Comment: 27 pages, 5 figures, special issue of Journal of Physics: Condensed
Matter on "Classical density functional theory methods in soft and hard
matter
Resistive MHD reconstruction of two-dimensional coherent structures in space
We present a reconstruction technique to solve the steady resistive MHD equations in two dimensions with initial inputs of field and plasma data from a single space- craft as it passes through a coherent structure in space. At least two components of directly measured electric fields (the spacecraft spin-plane components) are required for the reconstruction, to produce two-dimensional (2-D) field and plasma maps of the cross section of the structure. For con- venience, the resistivity tensor η is assumed diagonal in the reconstruction coordinates, which allows its values to be es- timated from Ohm’s law, E+v×B=η·j. In the present paper, all three components of the electric field are used. We benchmark our numerical code by use of an exact, axi- symmetric solution of the resistive MHD equations and then apply it to synthetic data from a 3-D, resistive, MHD numer- ical simulation of reconnection in the geomagnetic tail, in a phase of the event where time dependence and deviations from 2-D are both weak. The resistivity used in the simu- lation is time-independent and localized around the recon- nection site in an ellipsoidal region. For the magnetic field, plasma density, and pressure, we find very good agreement between the reconstruction results and the simulation, but the electric field and plasma velocity are not predicted with the same high accuracy
The Unveiling of Lodgism vs. Christianity: Positively Discussed Only In The Light of Its Most Friendly and Authorized Source of Information by Representative Men of God
https://digitalcommons.acu.edu/crs_books/1061/thumbnail.jp
Stability of Colloidal Quasicrystals
Freezing of charge-stabilized colloidal suspensions and relative stabilities
of crystals and quasicrystals are studied using thermodynamic perturbation
theory. Macroion interactions are modelled by effective pair potentials
combining electrostatic repulsion with polymer-depletion or van der Waals
attraction. Comparing free energies -- counterion terms included -- for
elementary crystals and rational approximants to icosahedral quasicrystals,
parameters are identified for which one-component quasicrystals are stabilized
by a compromise between packing entropy and cohesive energy.Comment: 6 pages, 4 figure
Trace Element Partitioning between CAI-Type Melts and Grossite, Melilite, Hibonite, and Olivine
We determined the mineral-melt partition coefficients (Di's) and the
compositional and/or temperature dependency between grossite, melilite,
hibonite, olivine and Ca-, Al-inclusion (CAI)-type liquids for a number of
light (LE), high field strength (HFSE), large ion lithophile (LILE), and rare
earth (REE) elements including Li, Be, B, Sr, Zr, Nb, Ba, La, Ce, Eu, Dy, Ho,
Yb, Hf, Ta, Th. A series of isothermal crystallization experiments was
conducted at 5 kbar pressure and IW+1 in graphite capsules. The starting
compositions were selected based on the calculated and experimentally confirmed
phase relations during condensation in CI dust-enriched systems (Ebel and
Grossman, 2000; Ebel, 2006; Ustunisik et al., 2014). Partition coefficients
between melt and gehlenite, hibonite, and grossite show that the trace element
budget of igneous CAIs is controlled by these three major Al-bearing phases in
addition to pyroxene. In general, LE, LILE, REE, and HFSE partition
coefficients (by mass) decrease in the order of Di(Gehlenite-Melt) >
Di(Hibonite-Melt) > Di(Grossite-Melt). Results suggest that Di(Gehlenite-Melt)
vary by a factor of 2-3 in different melt compositions at the same T (~1500 C).
Increased melt Al and Ca, relative to earlier work, increases the compatibility
of Di(Gehlenite-Melt), and also the compatibility of Di(Hibonite-Melt),
especially for La and Ce. Olivine partitioning experiments confirm that olivine
contribution to the trace element budget of CAIs is small due to the low
Di(Olivine-Melt) at a range of temperatures while D-Eu, Yb(Olivine-Melt) are
sensitive to changes in T and oxygen fugacity. The development of a predictive
model for partitioning in CAI-type systems would require more experimental data
and the use of analytical instruments capable of obtaining single phase
analyses for crystals < 5 micron.Comment: 23 pages, 15 figures, 5 table
Pharmacology of DB844, an orally active aza analogue of pafuramidine, in a monkey model of second stage human African trypanosomiasis
Novel drugs to treat human African trypanosomiasis (HAT) are still urgently needed despite the recent addition of nifurtimox-eflornithine combination therapy (NECT) to WHO Model Lists of Essential Medicines against second stage HAT, where parasites have invaded the central nervous system (CNS). The pharmacology of a potential orally available lead compound, N-methoxy-6-{5-[4-(N-methoxyamidino) phenyl]-furan-2-yl}-nicotinamidine (DB844), was evaluated in a vervet monkey model of second stage HAT, following promising results in mice. DB844 was administered orally to vervet monkeys, beginning 28 days post infection (DPI) with Trypanosoma brucei rhodesiense KETRI 2537. DB844 was absorbed and converted to the active metabolite 6-[5-(4-phenylamidinophenyl)-furanyl-2-yl]-nicotinamide (DB820), exhibiting plasma C(max) values of 430 and 190 nM for DB844 and DB820, respectively, after the 14th dose at 6 mg/kg qd. A 100-fold reduction in blood trypanosome counts was observed within 24 h of the third dose and, at the end of treatment evaluation performed four days post the last drug dose, trypanosomes were not detected in the blood or cerebrospinal fluid of any monkey. However, some animals relapsed during the 300 days of post treatment monitoring, resulting in a cure rate of 3/8 (37.5%) and 3/7 (42.9%) for the 5 mg/kgĂ—10 days and the 6 mg/kgĂ—14 days dose regimens respectively. These DB844 efficacy data were an improvement compared with pentamidine and pafuramidine both of which were previously shown to be non-curative in this model of CNS stage HAT. These data show that synthesis of novel diamidines with improved activity against CNS-stage HAT was possible
Counterion Penetration and Effective Electrostatic Interactions in Solutions of Polyelectrolyte Stars and Microgels
Counterion distributions and effective electrostatic interactions between
spherical macroions in polyelectrolyte solutions are calculated via
second-order perturbation (linear response) theory. By modelling the macroions
as continuous charge distributions that are permeable to counterions,
analytical expressions are obtained for counterion profiles and effective pair
interactions in solutions of star-branched and microgel macroions. The
counterions are found to penetrate stars more easily than microgels, with
important implications for screening of bare macroion interactions. The
effective pair interactions are Yukawa in form for separated macroions, but are
softly repulsive and bounded for overlapping macroions. A one-body volume
energy, which depends on the average macroion concentration, emerges naturally
in the theory and contributes to the total free energy.Comment: 15 pages, 5 figure
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