404 research outputs found
Height cohorts and district of residence in the city of Madrid during the 20th century
OBJECTIVE: in recent decades, an interesting literature has accumulated regarding the biological living standard in Spain at the end of the 19th Century and during the 20th Century. Adult height has been one of the most studied variables, specifically its temporal change at the national and provincial levels, the impact of the Civil War and the subsequent dictatorship, and the differences between urban and rural areas. We want to contribute to this general overview with the presentation of a project about an intra-urban perspective of the city of Madrid. METHODS: We present the stature data of the male population of two Madrid districts, Salamanca and Vallecas, for the period 1936-1986 (year of measurement). RESULTS: In these years, height increased by 5.58 cm, from 166.40 to 171.98 cm, with significant differences observed between both districts as well as a simultaneous decrease of that difference, for those born in 1915 and 1953 from 3.09 to 1.2 cm. The negative effect of the Civil War and the years of autarky are also observed in this urban sample. CONCLUSION: Considering these data together with those available for other demographic and socioeconomic variables, before and after the period studied, we can conclude that the division by districts represents an effective stratification in the biological living standard of the population of the city of Madrid. These results constitute a first intra-urban approximation using height to the debate on inequality and biological living standards in Spain during the 20th Century.Objetivo: en las últimas décadas se ha acumulado una interesante bibliografÃa sobre los niveles biológicos de vida en España a finales del siglo
xix y durante el siglo xx. La talla ha sido una de las variables más estudiadas: su cambio a nivel nacional y provincial, el impacto de la Guerra Civil
y de la posterior dictadura y las diferencias entre las áreas urbanas y las rurales. Queremos contribuir a este panorama general con este trabajo,
una perspectiva intraurbana de la ciudad de Madrid.
Métodos: presentamos el análisis comparativo del cambio temporal en la talla de los madrileños de los distritos de Salamanca y de Vallecas
correspondientes al periodo 1936-1986.
Resultados: en esos años, la talla total se incrementó en 5,58 cm, pasando de 166,40 a 171,98 cm, aunque se observan diferencias significativas
entre ambos distritos; diferencias que se reducen (de 3,09 a 1,2 cm) entre Salamanca y Vallecas para los nacidos en 1915 y 1953,
respectivamente. También se observa el efecto negativo de la Guerra Civil y de los años de autarquÃa.
Conclusión: considerando estos primeros datos, junto a los disponibles para otras variables demográficas y socioeconómicas previas y posteriores
al periodo estudiado, podemos considerar que la división por distritos representa una estratificación efectiva en los niveles biológicos de vida
dentro de la ciudad de Madrid. Estos resultados constituyen una primera aproximación intraurbana con la talla al debate sobre la desigualdad y los niveles de vida en España durante el siglo xxLa publicación de este trabajo ha sido sufragada con fondos del proyecto HAR2016-
76814-C2-2-P del Ministerio de EconomÃa, Industria y Competitividad (MINECO-FEDER-UE
Interplay of spin density wave and superconductivity with different pairing symmetry
A model study for the coexistence of the spin density wave and
superconductivity is presented. With reference to the recent angle resolved
photo emmission experimental data in high T_c cuprates, presence of the nested
pieces of bands is assumed. The single band Hubbard model, therefore, when
treated within the Hatree-Fock mean field theory leads to a spin density wave
(SDW) ground state. The superconductivity (SC) is assumed to be due to a
generalised attractive potential with a separable form without specifying to
any particular origin. It therefore allows a comparative study of the
coexistence of superconductivity of different order parameter symmetry with the
spin density wave state. We find that the phase diagram, comprising of the
amplitudes of the respective gaps (SC and SDW) Vs. band filling resembles to
that of the high T_c cuprates only when the order parameter of the
superconducting phase has d-wave symmetry. Thermal variation of different order
parameters (e.g, SC and SDW) also show interesting coexistence and reentrance
behaviors that are consistent with experimental observations, specially for the
borocarbides.Comment: 8 pages, 6 figures (postscript attached), Physica C (in press
Doping a semiconductor to create an unconventional metal
Landau Fermi liquid theory, with its pivotal assertion that electrons in
metals can be simply understood as independent particles with effective masses
replacing the free electron mass, has been astonishingly successful. This is
true despite the Coulomb interactions an electron experiences from the host
crystal lattice, its defects, and the other ~1022/cm3 electrons. An important
extension to the theory accounts for the behaviour of doped semiconductors1,2.
Because little in the vast literature on materials contradicts Fermi liquid
theory and its extensions, exceptions have attracted great attention, and they
include the high temperature superconductors3, silicon-based field effect
transistors which host two-dimensional metals4, and certain rare earth
compounds at the threshold of magnetism5-8. The origin of the non-Fermi liquid
behaviour in all of these systems remains controversial. Here we report that an
entirely different and exceedingly simple class of materials - doped small gap
semiconductors near a metal-insulator transition - can also display a non-Fermi
liquid state. Remarkably, a modest magnetic field functions as a switch which
restores the ordinary disordered Fermi liquid. Our data suggest that we have
finally found a physical realization of the only mathematically rigourous route
to a non-Fermi liquid, namely the 'undercompensated Kondo effect', where there
are too few mobile electrons to compensate for the spins of unpaired electrons
localized on impurity atoms9-12.Comment: 17 pages 4 figures supplemental information included with 2 figure
The host metabolite D-serine contributes to bacterial niche specificity through gene selection
Escherichia coli comprise a diverse array of both commensals and niche-specific pathotypes. The ability to cause disease results from both carriage of specific virulence factors and regulatory control of these via environmental stimuli. Moreover, host metabolites further refine the response of bacteria to their environment and can dramatically affect the outcome of the host–pathogen interaction. Here, we demonstrate that the host metabolite, D-serine, selectively affects gene expression in E. coli O157:H7. Transcriptomic profiling showed exposure to D-serine results in activation of the SOS response and suppresses expression of the Type 3 Secretion System (T3SS) used to attach to host cells. We also show that concurrent carriage of both the D-serine tolerance locus (dsdCXA) and the locus of enterocyte effacement pathogenicity island encoding a T3SS is extremely rare, a genotype that we attribute to an ‘evolutionary incompatibility’ between the two loci. This study demonstrates the importance of co-operation between both core and pathogenic genetic elements in defining niche specificity
Parenting behavior and the risk of becoming a victim and a bully/victim : a meta-analysis study
Objective:
Being bullied has adverse effects on children's health. Children's family experiences and parenting behavior before entering school help shape their capacity to adapt and cope at school and have an impact on children's peer relationship, hence it is important to identify how parenting styles and parent–child relationship are related to victimization in order to develop intervention programs to prevent or mitigate victimization in childhood and adolescence.
Methods:
We conducted a systematic review of the published literature on parenting behavior and peer victimization using MEDLINE, PsychINFO, Eric and EMBASE from 1970 through the end of December 2012. We included prospective cohort studies and cross-sectional studies that investigated the association between parenting behavior and peer victimization.
Results:
Both victims and those who both bully and are victims (bully/victims) were more likely to be exposed to negative parenting behavior including abuse and neglect and maladaptive parenting. The effects were generally small to moderate for victims (Hedge's g range: 0.10–0.31) but moderate for bully/victims (0.13–0.68). Positive parenting behavior including good communication of parents with the child, warm and affectionate relationship, parental involvement and support, and parental supervision were protective against peer victimization. The protective effects were generally small to moderate for both victims (Hedge's g: range: −0.12 to −0.22) and bully/victims (−0.17 to −0.42).
Conclusions:
Negative parenting behavior is related to a moderate increase of risk for becoming a bully/victim and small to moderate effects on victim status at school. Intervention programs against bullying should extend their focus beyond schools to include families and start before children enter school
Optical-faint, far-infrared-bright Herschel sources in the CANDELS fields: Ultra-luminous infrared galaxies at z > 1 and the effect of source blending
The Herschel very wide-field surveys have charted hundreds of square degrees in multiple far-IR
(FIR) bands. While the Sloan Digital Sky Survey (SDSS) is currently the best resource for optical
counterpart identifications over such wide areas, it does not detect a large number of Herschel FIR
sources and leaves their nature undetermined. As a test case, we studied seven ''SDSS-invisible'', very
bright 250 m sources (S250 > 55 mJy) in the Cosmic Assembly Near-infrared Deep Extragalactic
Legacy Survey (CANDELS) fields where we have a rich multi-wavelength data set. We took a new
approach to decompose the FIR sources, using the near-IR or the optical images directly for position
priors. This is an improvement over the previous decomposition efforts where the priors are from
mid-IR data that still suffer from the source blending problem in the first place. We found that in
most cases the single Herschel sources are made of multiple components that are not necessarily at the
same redshifts. Our decomposition succeeded in identifying and extracting their major contributors.
We show that these are all ULIRGs at z 1 - 2 whose high LIR is mainly due to dust-obscured
star formation. Most of them would not be selected as sub-mm galaxies. They all have complicated
morphologies indicative of merger or violent instability, and their stellar populations are heterogeneous
in terms of stellar masses, ages and formation histories. Their current ULIRG phases are of various
degrees of importance in their stellar mass assembly. Our practice provides a promising starting point
to develop an automatic routine to reliably study bright Herschel sources.IS
Optical-Faint, Far-Infrared-Bright \u3cem\u3eHerschel\u3c/em\u3e Sources in the CANDELS Fields: Ultra-Luminous Infrared Galaxies at \u3cem\u3ez\u3c/em\u3e \u3e 1 and the Effect of Source Blending
The Herschel very wide field surveys have charted hundreds of square degrees in multiple far-IR (FIR) bands. While the Sloan Digital Sky Survey (SDSS) is currently the best resource for optical counterpart identifications over such wide areas, it does not detect a large number of Herschel FIR sources and leaves their nature undetermined. As a test case, we studied seven SDSS-invisible, very bright 250 μm sources (S 250 \u3e 55 mJy) in the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey fields where we have a rich multi-wavelength data set. We took a new approach to decompose the FIR sources, using the near-IR or the optical images directly for position priors. This is an improvement over the previous decomposition efforts where the priors are from mid-IR data that still suffer from the problem of source blending. We found that in most cases the single Herschel sources are made of multiple components that are not necessarily at the same redshifts. Our decomposition succeeded in identifying and extracting their major contributors. We show that these are all ultra-luminous infrared galaxies at z ~ 1-2 whose high L IR is mainly due to dust-obscured star formation. Most of them would not be selected as submillimeter galaxies. They all have complicated morphologies indicative of mergers or violent instability, and their stellar populations are heterogeneous in terms of stellar masses, ages, and formation histories. Their current ultra-luminous infrared galaxy phases are of various degrees of importance in their stellar mass assembly. Our practice provides a promising starting point for developing an automatic routine to reliably study bright Herschel sources
Electrically switchable Berry curvature dipole in the monolayer topological insulator WTe2
Recent experimental evidence for the quantum spin Hall (QSH) state in
monolayer WTe has bridged two of the most active fields of condensed matter
physics, 2D materials and topological physics. This 2D topological crystal also
displays unconventional spin-torque and gate-tunable superconductivity. While
the realization of QSH has demonstrated the nontrivial topology of the electron
wavefunctions of monolayer WTe, the geometrical properties of the
wavefunction, such as the Berry curvature, remain unstudied. On the other hand,
it has been increasingly recognized that the Berry curvature plays an important
role in multiple areas of condensed matter physics including nonreciprocal
electron transport, enantioselective optical responses, chiral polaritons and
even unconventional superconductivity. Here we utilize mid-infrared
optoelectronic microscopy to investigate the Berry curvature in monolayer
WTe. By optically exciting electrons across the inverted QSH gap, we
observe an in-plane circular photogalvanic current even under normal incidence.
The application of an out-of-plane displacement field further systematically
controls the direction and magnitude of the photocurrent. Our observed
photocurrent reveals a novel Berry curvature dipole that arises from the
nontrivial wavefunctions near the inverted gap edge. These previously
unrealized Berry curvature dipole and strong electric field effect are uniquely
enabled by the inverted band structure and tilted crystal lattice of monolayer
WTe. Such an electrically switchable Berry curvature dipole opens the door
to the observation of a wide range of quantum geometrical phenomena, such as
quantum nonlinear Hall, orbital-Edelstein and chiral polaritonic effects.Comment: Originally submitted version, main text combined with part of the S
Observation of the nonlinear Hall effect under time reversal symmetric conditions
The electrical Hall effect is the production of a transverse voltage under an
out-of-plane magnetic field. Historically, studies of the Hall effect have led
to major breakthroughs including the discoveries of Berry curvature and the
topological Chern invariants. In magnets, the internal magnetization allows
Hall conductivity in the absence of external magnetic field. This anomalous
Hall effect (AHE) has become an important tool to study quantum magnets. In
nonmagnetic materials without external magnetic fields, the electrical Hall
effect is rarely explored because of the constraint by time-reversal symmetry.
However, strictly speaking, only the Hall effect in the linear response regime,
i.e., the Hall voltage linearly proportional to the external electric field,
identically vanishes due to time-reversal symmetry. The Hall effect in the
nonlinear response regime, on the other hand, may not be subject to such
symmetry constraints. Here, we report the observation of the nonlinear Hall
effect (NLHE) in the electrical transport of the nonmagnetic 2D quantum
material, bilayer WTe2. Specifically, flowing an electrical current in bilayer
WTe2 leads to a nonlinear Hall voltage in the absence of magnetic field. The
NLHE exhibits unusual properties sharply distinct from the AHE in metals: The
NLHE shows a quadratic I-V characteristic; It strongly dominates the nonlinear
longitudinal response, leading to a Hall angle of about 90 degree. We further
show that the NLHE directly measures the "dipole moment" of the Berry
curvature, which arises from layer-polarized Dirac fermions in bilayer WTe2.
Our results demonstrate a new Hall effect and provide a powerful methodology to
detect Berry curvature in a wide range of nonmagnetic quantum materials in an
energy-resolved way
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