68,304 research outputs found
Coalescence of Liquid Drops
When two drops of radius touch, surface tension drives an initially
singular motion which joins them into a bigger drop with smaller surface area.
This motion is always viscously dominated at early times. We focus on the
early-time behavior of the radius \rmn of the small bridge between the two
drops. The flow is driven by a highly curved meniscus of length 2\pi \rmn and
width \Delta\ll\rmn around the bridge, from which we conclude that the
leading-order problem is asymptotically equivalent to its two-dimensional
counterpart. An exact two-dimensional solution for the case of inviscid
surroundings [Hopper, J. Fluid Mech. , 349 (1990)] shows that
\Delta \propto \rmn^3 and \rmn \sim (t\gamma/\pi\eta)\ln [t\gamma/(\eta
R)]; and thus the same is true in three dimensions. The case of coalescence
with an external viscous fluid is also studied in detail both analytically and
numerically. A significantly different structure is found in which the outer
fluid forms a toroidal bubble of radius \Delta \propto \rmn^{3/2} at the
meniscus and \rmn \sim (t\gamma/4\pi\eta) \ln [t\gamma/(\eta R)]. This basic
difference is due to the presence of the outer fluid viscosity, however small.
With lengths scaled by a full description of the asymptotic flow for
\rmn(t)\ll1 involves matching of lengthscales of order \rmn^2, \rmn^{3/2},
\rmn\rmn^{7/4}$.Comment: 36 pages, including 9 figure
Recurrent Memory Networks for Language Modeling
Recurrent Neural Networks (RNN) have obtained excellent result in many
natural language processing (NLP) tasks. However, understanding and
interpreting the source of this success remains a challenge. In this paper, we
propose Recurrent Memory Network (RMN), a novel RNN architecture, that not only
amplifies the power of RNN but also facilitates our understanding of its
internal functioning and allows us to discover underlying patterns in data. We
demonstrate the power of RMN on language modeling and sentence completion
tasks. On language modeling, RMN outperforms Long Short-Term Memory (LSTM)
network on three large German, Italian, and English dataset. Additionally we
perform in-depth analysis of various linguistic dimensions that RMN captures.
On Sentence Completion Challenge, for which it is essential to capture sentence
coherence, our RMN obtains 69.2% accuracy, surpassing the previous
state-of-the-art by a large margin.Comment: 8 pages, 6 figures. Accepted at NAACL 201
MULTI-INSTRUMENTAL IDENTIFICATION OF ORPIMENT IN ARCHAEOLOGICAL MORTUARY CONTEXTS
Indexación: Web of Science; Scielo.This paper reports on an unknown yellowish mineral compound found in an archaeological context from Chorrillos cemetery (Calama, Chile) dating to the Early Formative period (800 - 200 B.C.). We used optic microscopy, SEM, EDX, 1H-RMN, 13C-RMN, and infrared (IR) and Raman spectroscopy to tease out the chemical and molecular composition of the sample. The microscopic images show amorphous yellowish granulates with heterogeneous chemical surfaces. 1H-RMN and 13C-RMN negative results show that the sample is free of organic matter. The SEM and EDX indicate the presence of arsenic and sulfur in the sample. The IR and Raman analyses suggest the presence of orpiment which is a toxic yellow arsenic sulfide mineral.http://ref.scielo.org/mfcms
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