3,466 research outputs found
Trends in Software and Control
New software technologies are important for the future of control (and vice versa) in an age of increasing complexity. This paper discusses what are the trends
WILLINGNESS TO PAY FOR ENVIRONMENTAL SERVICES AMONG SLASH-AND-BURN FARMERS IN THE PERUVIAN AMAZON: IMPLICATIONS FOR DEFORESTATION AND GLOBAL ENVIRONMENTAL MARKETS
A Contingent Valuation survey shows that the possibility of trade in carbon sequestration services exists between utility companies and slash-and-burn farmers in the Amazon and that farmers positively value the environmental services of the forest. Global environmental markets could enhance the effectiveness of traditional forest conservation efforts while benefitting resource-poor farmers.Environmental Economics and Policy,
Scalable Semantic Matching of Queries to Ads in Sponsored Search Advertising
Sponsored search represents a major source of revenue for web search engines.
This popular advertising model brings a unique possibility for advertisers to
target users' immediate intent communicated through a search query, usually by
displaying their ads alongside organic search results for queries deemed
relevant to their products or services. However, due to a large number of
unique queries it is challenging for advertisers to identify all such relevant
queries. For this reason search engines often provide a service of advanced
matching, which automatically finds additional relevant queries for advertisers
to bid on. We present a novel advanced matching approach based on the idea of
semantic embeddings of queries and ads. The embeddings were learned using a
large data set of user search sessions, consisting of search queries, clicked
ads and search links, while utilizing contextual information such as dwell time
and skipped ads. To address the large-scale nature of our problem, both in
terms of data and vocabulary size, we propose a novel distributed algorithm for
training of the embeddings. Finally, we present an approach for overcoming a
cold-start problem associated with new ads and queries. We report results of
editorial evaluation and online tests on actual search traffic. The results
show that our approach significantly outperforms baselines in terms of
relevance, coverage, and incremental revenue. Lastly, we open-source learned
query embeddings to be used by researchers in computational advertising and
related fields.Comment: 10 pages, 4 figures, 39th International ACM SIGIR Conference on
Research and Development in Information Retrieval, SIGIR 2016, Pisa, Ital
Multiple Chemodynamic Stellar Populations of the Ursa Minor Dwarf Spheroidal Galaxy
We present a Bayesian method to identify multiple (chemodynamic) stellar
populations in dwarf spheroidal galaxies (dSphs) using velocity, metallicity,
and positional stellar data without the assumption of spherical symmetry. We
apply this method to a new Keck/DEIMOS spectroscopic survey of the Ursa Minor
(UMi) dSph. We identify 892 likely members, making this the largest UMi sample
with line-of-sight velocity and metallicity measurements. Our Bayesian method
detects two distinct chemodynamic populations with high significance
(). The metal-rich () population is
kinematically colder (radial velocity dispersion of ) and more centrally concentrated than the metal-poor () and kinematically hotter population (). Furthermore, we apply the same analysis to
an independent MMT/Hectochelle data set and confirm the existence of two
chemodynamic populations in UMi. In both data sets, the metal-rich population
is significantly flattened () and the metal-poor
population is closer to spherical (). Despite
the presence of two populations, we are unable to robustly estimate the slope
of the dynamical mass profile. We found hints for prolate rotation of order
in the MMT data set, but further observations
are required to verify this. The flattened metal-rich population invalidates
assumptions built into simple dynamical mass estimators, so we computed new
astrophysical dark matter annihilation (J) and decay profiles based on the
rounder, hotter metal-poor population and inferred
for the Keck
data set. Our results paint a more complex picture of the evolution of Ursa
Minor than previously discussed.Comment: 20 pages, 11 figures, data included. Comments welcome. Accepted to
MNRA
Evaluación in vitro de filtración hacia conducto radicular de dos sistemas de reconstrucción post endodóncica
ResumenEl objetivo de este estudio fue el de evaluar el grado de microfiltración en dos sistemas de reconstrucción postendodóncica, valorando la penetración de un colorante a lo largo de las restauraciones realizadas con endopostes y cementos duales de resina. En este estudio se emplearon 30 dientes premolares unirradiculares extraídos a los que se les realizó tratamiento de conductos y almacenándolos en agua bidestilada a 37 °C. Se distribuyeron los dientes en tres grupos de forma aleatoria, con diez dientes por cada grupo. La cementación de los postes se realizó en dos de los grupos, usando los sistemas RelyX Fiber post (3M ESPE dental products) y Parapost (Coltene-Whaledent). Las muestras fueron sometidas al proceso de termociclado y posterior inmersión en azul de metileno por siete días a 36 °C. Posteriormente se diafanizaron las muestras y fueron analizadas bajo microscopio, obteniendo los valores de penetración en milímetros. Los resultados mostraron que los dientes tratados con el sistema Parapost presentaron menor microfiltración. El grupo control mostró el mayor índice de microfiltración. El análisis estadístico con la prueba de Donett mostró diferencia estadísticamente significativa entre los sistemas Parapost y RelyX.ConclusiónSe demostró que el sistema de reconstrucción Parapost (Coltene-Whaledent), el cual tiene una técnica de grabado ácido, reportó menores valores de microfiltración, siendo los resultados estadísticamente significativos con respecto a los obtenidos con el sistema de reconstrucción RelyX (3M ESPE dental products).AbstractThe aim of the present study was to assess the degree of microleakage observed when using two different post-endodontic reconstruction systems; this was achieved assessing penetration of a dye along restorations performed with endodontic posts and dual-cure resin cements. For the present study, 30 extracted, single rooted premolars were used. Root canal treatment was performed on the teeth which were later stored in bi-distilled water at 37 °C. Teeth were randomly allotted to three groups, all groups were comprised of 10 teeth. In two groups, post cementation was performed using the systems RelyX Fiber Post (3M ESPE dental products) and Parapost (Coltene-Whaledent). Samples were subjected to thermo-cycling and later immersed in methylene blue for seven days at 36 °C. After this, samples were subjected to a diaphanization process and were then analyzed under a microscope; penetration in millimeters was thus obtained. Results revealed that teeth treated with Parapost system exhibited lesser microleakage. Control group experienced the greater amounts of microleakage. Statistical analysis conducted with Donett test showed statistically significant difference between Parapost and RelyX systems.ConclusionParapost reconstruction system (Coltene-Whaledent) with acid-etch technique exhibited lower microleakage values. Results were statistically significant when compared to those obtained with the RelyX reconstruction system (3M ESPE dental products)
Control of open quantum systems via dynamical invariants
In this work, we confront the challenge of controlling quantum systems that
are influenced by their environment, utilizing the theory of dynamical
invariants. Our strategy involves a reverse engineering method for formulating
control protocols like Shortcuts to Adiabaticity (STA), tailored to be
resilient against environmental noise and dissipation. This technique offers
two main advantages compared to other quantum control methods: firstly, it
incorporates the time-varying aspect of the dissipation factor in the master
equation, which arises from driving the system's Hamiltonian (the control
fields). Secondly, our method eliminates the need for iterative propagation of
the system state, a process that is typically resource-intensive. The efficacy
and practicality of our approach are demonstrated through the application to
two fundamental models: a two-level quantum system and a quantum harmonic
oscillator, each interacting with a thermal bath
Invariant-based control of quantum many-body systems across critical points
Quantum many-body systems are emerging as key elements in the quest for
quantum-based technologies and in the study of fundamental physics. In this
context, finding control protocols that allow for fast and high fidelity
evolutions across quantum phase transitions is of particular interest. Ideally,
such controls should be scalable with the system size and not require
controllable and unwanted extra interactions. In addition, its performance
should be robust against potential imperfections. Here we design an
invariant-based control technique that ensures perfect adiabatic-like evolution
in the lowest energy subspace of the many-body system, and is able to meet all
these requirements -- tuning the controllable parameter according to the
analytical control results in high-fidelity evolutions operating close to the
speed limit, valid for any number particles. As such, Kibble-Zurek scaling laws
break down, leading to tunable and much better time scaling behavior. We
illustrate our findings by means of detailed numerical simulations in the
transverse-field Ising and long-range Kitaev models and demonstrate the
robustness against noisy controls and disorder
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