2,231 research outputs found
Cryogenic magnetocaloric effect in the Fe17 molecular nanomagnet
Trabajo presentado al "The 23rd IIR International Congress of Refrigeration" celebrado del 21 al 26 de Agosto del 2011 en Praga.-- Dedicated to Alfred Werner on the 100th Anniversary of his Nobel prize in Chemistry in 1913.We study the magnetothermal properties of magnetically isotropic high-spin molecular nanomagnets containing 17 Fe3+ ions per molecule linked via oxide and hydroxide ions, packed in a crystallographic cubic symmetry. Low-temperature magnetization and heat capacity experiments reveal that each molecular unit carries a net spin ground state as large as S = 35/2 and a magnetic anisotropy as small as D = −0.023 K, while no magnetic order, purely driven by dipolar interactions, is to be expected down to very-low temperatures. These characteristics suggest that the Fe17 molecular nanomagnet can potentially be employed as a sub-Kelvin magnetic refrigerant.This work has been partially supported by Spanish MINECO through grants MAT2009-13977-C03 and PIE201060I012, the EPSRC and The Leverhulme Trust (UK).Peer Reviewe
Inter-Judge Agreement: An Analysis of the 1990 NFA and AFA-NIET National Individual Events Tournaments
Given the increasing concern about the judge\u27s role in individual events tournaments, and given the paucity of literature specifically pertaining to inter-judge agreement, we sought to analyze the degree of inter-judge agreement at two national level tournaments which employ multiple judge panels in preliminary rounds. The results of the 1990 National Forensics Association Tournament and the 1990 American Forensic Association - National Individual Events Tournament serve as a basis for the analysis
An Adaptive Sampling Scheme to Efficiently Train Fully Convolutional Networks for Semantic Segmentation
Deep convolutional neural networks (CNNs) have shown excellent performance in
object recognition tasks and dense classification problems such as semantic
segmentation. However, training deep neural networks on large and sparse
datasets is still challenging and can require large amounts of computation and
memory. In this work, we address the task of performing semantic segmentation
on large data sets, such as three-dimensional medical images. We propose an
adaptive sampling scheme that uses a-posterior error maps, generated throughout
training, to focus sampling on difficult regions, resulting in improved
learning. Our contribution is threefold: 1) We give a detailed description of
the proposed sampling algorithm to speed up and improve learning performance on
large images. We propose a deep dual path CNN that captures information at fine
and coarse scales, resulting in a network with a large field of view and high
resolution outputs. We show that our method is able to attain new
state-of-the-art results on the VISCERAL Anatomy benchmark
Tunable dipolar magnetism in high-spin molecular clusters
We report on the Fe17 high-spin molecular cluster and show that this system
is an exemplification of nanostructured dipolar magnetism. Each Fe17 molecule,
with spin S=35/2 and axial anisotropy as small as D=-0.02K, is the magnetic
unit that can be chemically arranged in different packing crystals whilst
preserving both spin ground-state and anisotropy. For every configuration,
molecular spins are correlated only by dipolar interactions. The ensuing
interplay between dipolar energy and anisotropy gives rise to macroscopic
behaviors ranging from superparamagnetism to long-range magnetic order at
temperatures below 1K.Comment: Replaced with version accepted for publication in Physical Review
Letter
Atmospheric water vapor absorption at 12 CO2 laser frequencies
Measurements of the absorption of CO2 laser radiation in the 9.4 micron band by pressure broadened water vapor samples are summarized. The water vapor temperatures used were 25, 30, and 35 C
Self-gravitating domain walls and the thin-wall limit
We analyse the distributional thin wall limit of self gravitating scalar
field configurations representing thick domain wall geometries. We show that
thick wall solutions can be generated by appropiate scaling of the thin wall
ones, and obtain an exact solution for a domain wall that interpolates between
AdS_4 asymptotic vacua and has a well-defined thin wall limit.Solutions
representing scalar field configurations obtained via the same scaling but that
do not have a thin wall limit are also presented.Comment: 10 pages, revte
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