397 research outputs found
A simulation tool for the analysis and design of leaky wave antennas in laterally shielded planar technology with application to metamaterials
Leaky-waves have been a topic of increasing interest in the last years, with diverse practical applications in many different engineering fields. From periodic, FSS, EBG or even metamaterial leaky-wave based antennas to waveguide filters and higher efficiency energy guiding, they all share a common base structure: a travelling-wave propagating within a metal encapsulation, that can be open or closed, and altered by a planar metallization of periodic nature, from which the energy may radiate. Due to the fact that these antennas are usually electrically large and the periodic printed circuit requires a certain grade of complexity, 3D commercial software is prohibitively time consuming. Also, the homebrew methods developed up to this day are either not rigorous and accurate enough or unable to deal with complex periodic geometries. At this point, the evolution of leaky-wave antennas needs a solid, efficient and versatile tool where to base the future design research on.
In this work a novel simulation tool for waveguide embedded leaky-wave antennas is presented. It is based on a full-wave Method of Moments applied to the spectral domain Green Functions for a rigorous modal analysis of the finite structure. The use of Subdomain basis functions allows the software to model complex periodic geometries, overcoming a main limitation, and the analytical nature of the method combined with its 2.5D approach, results in a significant computing time reduction. It is built on a modular coding philosophy and provided with a user-friendly graphical interface, and an intuitive working procedure, making the program not only fast and accurate, but also easy to use and extend to new geometries. Finally, it is remarkable the educational potential of this new analysis software, since it identifies higher order effects as bandgaps and multi-harmonic radiation from a complete and simple modal approach
Empirical Bayes methods corrected for small numbers of tests
Histogram-based empirical Bayes methods developed for analyzing data for
large numbers of genes, SNPs, or other biological features tend to have large
biases when applied to data with a smaller number of features such as genes
with expression measured conventionally, proteins, and metabolites. To analyze
such small-scale and medium-scale data in an empirical Bayes framework, we
introduce corrections of maximum likelihood estimators (MLE) of the local false
discovery rate (LFDR). In this context, the MLE estimates the LFDR, which is a
posterior probability of null hypothesis truth, by estimating the prior
distribution. The corrections lie in excluding each feature when estimating one
or more parameters on which the prior depends. An application of the new
estimators and previous estimators to protein abundance data illustrates how
different estimators lead to very different conclusions about which proteins
are affected by cancer.
The estimators are compared using simulated data of two different numbers of
features, two different detectability levels, and all possible numbers of
affected features. The simulations show that some of the corrected MLEs
substantially reduce a negative bias of the MLE. (The best-performing corrected
MLE was derived from the minimum description length principle.) However, even
the corrected MLEs have strong negative biases when the proportion of features
that are unaffected is greater than 90%. Therefore, since the number of
affected features is unknown in the case of real data, we recommend an
optimally weighted combination of the best of the corrected MLEs with a
conservative estimator that has weaker parametric assumptions.Comment: This version adds new methods and a simulation stud
Between food ethics, solidarity and the social construction of alternative markets. Exploring the dimensions of grassroots food movements in Spain
In recent years there has been growing attention for the emergence of alternative food networks, first as a possible strategy for farm households to counter deteriorating market conditions and respond to changing societal demands, and more recently as expression of a growing consumer involvement in the shaping of food systems. In debates on AFNs contributions from Spain have been relatively scarce, not because these tendencies do not occur but rather because applied analytical frameworks somehow did not seem to capture the specific nature of experiences in the peninsula. Against this background, this paper aims to analyze emerging grassroots food movements in Spain, explore to what extent different initiatives constitute a coherent alternative
paradigm for sustainable local food systems, and identify relevant dimensions that shape their development and potential contribution to the sustainable development of rural areas and society at large. The paper is mainly based on case studies from Andalucia and the Basque country, and stresses that food initiatives have been largely driven by social movements, incl. peasant‐based farmers and consumer groups but also agroecology movements. As a result, Spanish food movements often have a wider focus and combine ethical values
like fairness, solidarity and participative democracy with economic and environmental concerns
Paternity and maternity. Synonyms?
Con este relato se pretende conocer las vivencias, emociones, anécdotas… de cómo cambia la vida de una mujer, tras la pérdida de su madre a la edad de 12 años y cómo su padre se adapta a esta tragedia para convertirse en su principal cuidador. Comienza a ejercer ambos roles a la vez, el de padre y madre, llevando a cabo una conciliación familiar y laboral. Su historia nos hará entender como la paternidad y la maternidad no tienen por qué pertenecer a un rol u otro, y como esta tragedia ayuda a florecer la maternidad oculta en su padre.With this story is intended to know the experiences, emotions, anecdotes... how a woman's life changes, after the loss of her mother at the age of 12 and how her father adapts to this tragedy to become his main caretaker. It begins to exercise both roles at the same time, the one of father and mother, carrying out a family and labor conciliation. Her story will make us understand how paternity and motherhood do not have to belong to one role or another, and how this tragedy helps to flourish the motherhood hidden in her father
Optimization of thin sheet structures with patterns perforations
Mestrado em Engenharia MecânicaNowadays,
metal
storage
systems
are
generally
used
in
industrial
companies.
The
several
stages
of
the
metallic
structures
design
are
based
in
the
standard
EN
15512:2009.
However,
this
standard
do
not
the
most
efficient
design
solution,
only
design
constraints.
In
this
work,
it
is
intended
to
improve
the
structural
elements
that
are
on
the
base
of
the
metal
storage
systems,
particularly
shelves,
in
order
to
reduce
costs
and
increase
the
structure
stiffness,
enforcing
the
international
standard
that
define
the
characteristics
of
these
products.
The
main
purpose
is
the
optimization
of
a
representative
section
of
profiled
steel
component
taking
into
account
the
variable
thickness,
geometry
and
number
of
perforations.
In
order
to
do
this
a
computational
finite
element
model
is
developed
and
pre-‐validated,
replacing
a
numerous
set
of
experimental
tests
in
a
design
of
Experiments
(DoE)
methodology.
The
optimized
solutions
were
obtained
through
a
response
surface
optimization
methodology
(RSM).
The
final
results
were
analysed
and
discussed.Hoje
em
dia,
os
sistemas
metálicos
de
armazenamento
são
vulgarmente
utilizados
pela
indústria.
As
várias
etapas
de
projeto
destas
estruturas
metálicas
são
baseadas
na
norma
EN
15512:2009.
No
entanto,
esta
norma
não
propõe
a
solução
de
projeto
mais
eficiente,
apenas
as
suas
restrições.
Neste
trabalho,
pretende-‐se
aperfeiçoar
os
elementos
estruturais
que
estão
na
base
dos
sistemas
de
armazenamento
de
metal,
particularmente
prateleiras,
a
fim
de
reduzir
custos
e
aumentar
a
rigidez
da
estrutura,
satisfazendo
a
norma
internacional
que
define
as
características
necessárias
desses
produtos.
O
objetivo
principal
é
a
otimização
de
uma
secção
representativa
do
componente
de
aço
perfilado
tendo
em
conta
as
variáveis
espessura,
geometria
e
número
de
perfurações.
Para
isso,
é
desenvolvido
e
validado
um
modelo
computacional
de
elementos
finitos,
substituindo
um
numeroso
conjunto
de
testes
experimentais
numa
metodologia
de
Design
of
Experiments
(DoE).
As
soluções
otimizadas
são
obtidas
através
de
uma
metodologia
de
otimização
baseada
numa
superfície
de
resposta
(RSM).
Os
resultados
finais
são
analisados
e
discutidos
Variacions de la refracció perifèrica en els diferents meridians oculars
Aquest estudi mesura l’error refractiu perifèric i analitza les asimetries refractives en les
diferents zones de la retina d’una mostra de subjectes joves.Este estudio mide el error refractivo periférico y analiza las asimetrías refractivas en
diferentes zonas de la retina de una muestra de sujetos jóvenes.This study analyzes the peripheral refraction and analyzes refractive asymmetries on
different retinal areas of a sample young subject
Review of the literature on the influence of gender in Nursing
Existe gran cantidad de artículos que señalan la influencia de estereotipos de género en la enfermería, influyendo de forma negativa con respecto a la incorporación del hombre a esta profesión, obstaculizando su acceso. Además de originar un prestigio desfavorable de la profesión enfermera ante la sociedad. Por otro lado, hallamos desde una perspectiva de género, aspectos negativos originados por Florence Nightingale y la profesionalización de la enfermería. Es decir, Florence Nightingale, como impulsora de este cambio, favoreció la persistencia de los estereotipos de género, negándole al hombre su participación en el cuidado formal, en la enfermería.There is a large number of articles that indicate the influence of gender stereotypes in nursing, negatively influencing the incorporation of men into this profession, hindering their access. Besides giving rise to an unfavorable prestige of the nursing profession before the society. On the other hand, we find from a gender perspective, negative aspects originated by Florence Nightingale and the professionalization of nursing. That is, Florence Nightingale, as the promoter of this change, favored the persistence of gender stereotypes, denying men their participation in formal care, in nursing
Participatory Guarantee Systems in Spain: Motivations, Achievements, Challenges and Opportunities for Improvement Based on Three Case Studies
The increasing number of producers and consumers of organic products means that there is an increasing need to guarantee the organic characteristics of organic products. Certification is a tool that bridges the information deficit between demand and supply, ensuring that a product complies with the specified standards. Third-party certification (TPC) is the main tool for assessing compliance today. However, there have been criticisms about the suitability of TPC for small-scale producers and alternative certification systems have been developed, such as Participatory Guarantee Systems (PGS). PGS are quality assurance systems in which stakeholders are expected to be involved and assure the quality claims being made by producers. This paper presents three PGS initiatives in Spain. The research methods used in this study were semi-structured and structured interviews. Interviewees felt that their PGS initiatives fulfilled the important motivations of building a community and adding value to their products. The main challenges mentioned were the participation of stakeholders and the efficiency of internal organization. The absence of official recognition for PGS in Spain and insufficient dissemination were also perceived as challenges. Although PGS has the potential for further development in Spain, the interviewees believed that more support and official recognition were still required
C3-symmetry Mo3S4 aminophosphino clusters combining three sources of stereogenicity: stereocontrol directed by hydrogen bond interactions and ligand configuration
A diastereoselective synthesis of proline containing aminophosphino cubane-type Mo3S4 clusters,
(P)-[Mo3S4Cl3((1S,2R)-PPro)3]Cl ((P)-[Mo-(SN,RC)]Cl) and (P)-[Mo3S4Cl3((1S,2S)-PPro)3]Cl ((P)-[Mo-(SN,SC)]
Cl), has been achieved in high yields by reacting the corresponding enantiomerically pure PPro ((R)- and
(S)-2-[(diphenylphosphino)methyl]pyrrolidine) ligands with the Mo3S4Cl4(PPh3)3(H2O)2 complex. Circular
dichroism, nuclear magnetic resonance and X-ray techniques confirm that the (P)-[Mo-(SN,RC)]Cl and
(P)-[Mo-(SN,SC)]Cl cluster cations are diastereoisomers which combine three sources of stereogenicity
provided by the cluster framework, one carbon atom of the aminophosphine ligand and the nitrogen
stereogenic center. The higher stability of the (P)-[Mo-(SN,SC)]+ cation is due to stabilizing vicinal Cl⋯HN
interactions as well as due to the cis-fused conformation of the bicyclic system formed upon
coordination of the aminophosphine ligand.The financial support of the Spanish Ministerio de Economía y
Competitividad (Grant CTQ2011-23157 and CTQ2015-65207-P),
Universitat Jaume I (Research Project P1·1B2013-19) and
Generalitat Valenciana (PROMETEOII/2014/022) is gratefully
acknowledged. The authors also thank the Servei Central
d’Instrumentació Científica (SCIC) of the University Jaume I
for providing us with the mass spectrometry, NMR and X-ray
facilities. C. A. thanks the Spanish Ministerio de Economía y
Competitividad for a predoctoral fellowship (FPI)
Influence of the Diphosphine Coordinated to Molybdenum and Tungsten Triangular M3S4 Cluster Hydrides in the Catalytic Hydrodefluorination of Pentafluoropyridine
Hydrido molybdenum and tungsten(IV) cluster cations of formula [M3S4H3(dppe)3]+ (dppe = 1,2-(bis)dimethylphosphinoethane), [Mo-1]+ (M = Mo) and [W-1]+ (M = W), have been isolated by reacting their halide precursors with borohydride. Synthetic procedures have been optimized by appropriate choice of the solvent. Furthermore, [M3S4F3(dppe)3]+ fluorido cluster complexes, [Mo-2]+ (M = Mo) and [W-2]+ (M = W) have been prepared through halogen substitution reactions using an excess of cesium fluoride. The structures of [Mo-1]+ and [Mo-2]+ have been determined by single crystal X-ray diffraction experiments. These [M-1]+ hydrido and [M-2]+ fluorido clusters have been used as catalysts and precatalysts, respectively, in the catalytic hydrodefluorination (HDF) of pentafluoropyridine using HSiMe2Ph as hydrogen source. The reaction proceeds under microwave and reflux conditions to selectively afford 2,3,5,6-tetrafluoropyridine. The [W-1]+ hydrido cluster is the most efficient catalyst with turnover numbers of 124, while the [Mo-1]+ hydrido cluster reacts faster. Fluorido [Mo-2]+ and [W-2]+ complexes provide lower yields and turnover numbers. In general, the molybdenum and tungsten [M-1]+ and [M-2]+ diphosphino complexes are more efficient than their dmpe (1,2-(bis)dimethylphosphinoethano) analogues and activate pentafluoropyridine under softer conditionsThe financial support of the Spanish Ministerio de Economía y Competitividad (Grant CTQ2011-23157), Universitat Jaume I (Research Project P1·1B2013-19) and Generalitat Valenciana (ACOMP/2013/215 and Prometeo/2009/053) is gratefully acknowledged. The authors also thank the Servei Central d’Instrumentació Científica (SCIC) of the University Jaume I for providing us with the mass spectrometry, NMR and X-ray facilities. C.A. thanks the Spanish Ministerio de Economía y Competitividad for a predoctoral fellowship (FPI)
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