4,009 research outputs found
TECHNICAL CHANGE AND AGRICULTURAL TRADE: THREE EXAMPLES (SUGARCANE, BANANAS, AND RICE)
The purpose of this paper is to examine three cases which provide some insight into the character of international transmission of technical change and its economic impacts and implications. These cases focus on three separate commodities, sugarcane, bananas, and rice. Each case presents different facets of the international movement of technological innovation.International Relations/Trade, Research and Development/Tech Change/Emerging Technologies,
Coherent coupling between surface plasmons and excitons in semiconductor nanocrystals
We present an experimental demonstration of strong coupling between a surface
plasmon propagating on a planar silver substrate, and the lowest excited state
of CdSe nanocrystals. Variable-angle spectroscopic ellipsometry measurements
demonstrated the formation of plasmon-exciton mixed states, characterized by a
Rabi splitting of 82 meV at room temperature. Such a coherent
interaction has the potential for the development of plasmonic non-linear
devices, and furthermore, this system is akin to those studied in cavity
quantum electrodynamics, thus offering the possibility to study the regime of
strong light-matter coupling in semiconductor nanocrystals at easily accessible
experimental conditions.Comment: 12 pages, 4 figure
Rotation of visual landmark cues influences the spatial response profile of hippocampal neurons in freely-moving homing pigeons
Pigeon hippocampal neurons display two spatial response profiles: location fields frequently at goals, and path fields connecting goals. We recorded from 15 location and six path cells, with color cues positioned near four goal locations. Following color cue rotation, most location cells (12/15) shifted their response fields; path cells (5/6) lost their fields. Therefore, local visual cues can independently define a reference frame for location cells, but path cells may be more broadly tuned to context or alternative reference frames
Multimodal Perception and Multicriterion Control of Nested Systems
The purpose of this report is to identify the essential characteristics of goal-directed whole-body motion. The report is organized into three major sections (Sections 2, 3, and 4). Section 2 reviews general themes from ecological psychology and control-systems engineering that are relevant to the perception and control of whole-body motion. These themes provide an organizational framework for analyzing the complex and interrelated phenomena that are the defining characteristics of whole-body motion. Section 3 of this report applies the organization framework from the first section to the problem of perception and control of aircraft motion. This is a familiar problem in control-systems engineering and ecological psychology. Section 4 examines an essential but generally neglected aspect of vehicular control: coordination of postural control and vehicular control. To facilitate presentation of this new idea, postural control and its coordination with vehicular control are analyzed in terms of conceptual categories that are familiar in the analysis of vehicular control
Understanding Skill in EVA Mass Handling
Key attributes of skilled mass handling were identified through an examination of lessons learned by the extravehicular activity operational community. These qualities were translated into measurable quantities. The operational validity of the ground-based investigation was improved by building a device that increased the degrees of freedom of extravehicular mobility unit motion on the Precision Air-Bearing Floor. The results revealed subtle patterns of interaction between motions of an orbital replacement unit mockup and mass handler that should be important for effective performance on orbit. The investigation also demonstrated that such patterns can be measured with a variety of common instruments and under imperfect conditions of observation
Higgs ID at the LHC
We make a complete catalog of extended Higgs sectors involving SU(2)_L
doublets and singlets, subject to natural flavor conservation. In each case we
present the couplings of a light neutral CP-even Higgs state h in terms of the
model parameters, and identify which models are distinguishable in principle
based on this information. We also give explicit expressions for the model
parameters in terms of h couplings and exhibit the behaviors of the couplings
in the limit where the deviations from the Standard Model Higgs couplings are
small. Finally we discuss prospects for differentiation of extended Higgs
models based on measurements at the LHC and ILC and identify the regions in
which these experiments could detect deviations from the SM Higgs predictions.Comment: 46 pages, 6 figures, 2 tables, PRD versio
Migrating to Cloud-Native Architectures Using Microservices: An Experience Report
Migration to the cloud has been a popular topic in industry and academia in
recent years. Despite many benefits that the cloud presents, such as high
availability and scalability, most of the on-premise application architectures
are not ready to fully exploit the benefits of this environment, and adapting
them to this environment is a non-trivial task. Microservices have appeared
recently as novel architectural styles that are native to the cloud. These
cloud-native architectures can facilitate migrating on-premise architectures to
fully benefit from the cloud environments because non-functional attributes,
like scalability, are inherent in this style. The existing approaches on cloud
migration does not mostly consider cloud-native architectures as their
first-class citizens. As a result, the final product may not meet its primary
drivers for migration. In this paper, we intend to report our experience and
lessons learned in an ongoing project on migrating a monolithic on-premise
software architecture to microservices. We concluded that microservices is not
a one-fit-all solution as it introduces new complexities to the system, and
many factors, such as distribution complexities, should be considered before
adopting this style. However, if adopted in a context that needs high
flexibility in terms of scalability and availability, it can deliver its
promised benefits
High efficiency GaAs-Ge tandem solar cells grown by MOCVD
High conversion efficiency and low weight are obviously desirable for solar cells intended for space applications. One promising structure is GaAs on Ge. The advantages of using Ge wafers as substrates include the following: they offer high efficiency by forming a two-junction tandem cell; low weight combined with superior strength allows usage of thin (3 mil) wafers; and they are a good substrate for GaAs, being lattice matched, thermal expansion matched, and available as large-area wafers
Gauss Sums and Quantum Mechanics
By adapting Feynman's sum over paths method to a quantum mechanical system
whose phase space is a torus, a new proof of the Landsberg-Schaar identity for
quadratic Gauss sums is given. In contrast to existing non-elementary proofs,
which use infinite sums and a limiting process or contour integration, only
finite sums are involved. The toroidal nature of the classical phase space
leads to discrete position and momentum, and hence discrete time. The
corresponding `path integrals' are finite sums whose normalisations are derived
and which are shown to intertwine cyclicity and discreteness to give a finite
version of Kelvin's method of images.Comment: 14 pages, LaTe
Multimodal Perception and Multicriterion Control of Nested Systems
This report reviews the operational demands made of a Shuttle pilot or commander within the context of a proven empirical methodology for describing human sensorimotor performance and whole-body coordination in mechanically and perceptually complex environments. The conclusions of this review pertain to a) methods for improving our understanding of the psychophysics and biomechanics of visual/manual control and whole-body coordination in space vehicle cockpits; b) the application of scientific knowledge about human perception and performance in dynamic inertial conditions to the development of technology, procedures, and training for personnel in space vehicle cockpits; c) recommendations for mitigation of safety and reliability concerns about human performance in space vehicle cockpits; and d) in-flight evaluation of flight crew performance during nominal and off-nominal launch and reentry scenarios
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