136 research outputs found
Electronic Structure of Charge- and Spin-controlled Sr_{1-(x+y)}La_{x+y}Ti_{1-x}Cr_{x}O_{3}
We present the electronic structure of
Sr_{1-(x+y)}La_{x+y}Ti_{1-x}Cr_{x}O_{3} investigated by high-resolution
photoemission spectroscopy. In the vicinity of Fermi level, it was found that
the electronic structure were composed of a Cr 3d local state with the
t_{2g}^{3} configuration and a Ti 3d itinerant state. The energy levels of
these Cr and Ti 3d states are well interpreted by the difference of the
charge-transfer energy of both ions. The spectral weight of the Cr 3d state is
completely proportional to the spin concentration x irrespective of the carrier
concentration y, indicating that the spin density can be controlled by x as
desired. In contrast, the spectral weight of the Ti 3d state is not
proportional to y, depending on the amount of Cr doping.Comment: 4 pages, 3 figures. Accepted for publication in Phys. Rev. Let
Orbital selectivity of the kink in the dispersion of Sr2RuO4
We present detailed energy dispersions near the Fermi level on the monolayer
perovskite ruthenate Sr2RuO4, determined by high-resolution angle-resolved
photoemission spectroscopy. An orbital selectivity of the kink in the
dispersion of Sr2RuO4 has been found: A kink for the Ru 4d_xy orbital is
clearly observed, but not for the Ru 4d_yz and 4d_zx ones. The result provides
insight into the origin of the kink.Comment: 5 pages, 4 figures. Accepted for publication in Phys. Rev.
Kinks in the dispersion of strongly correlated electrons
The properties of condensed matter are determined by single-particle and
collective excitations and their interactions. These quantum-mechanical
excitations are characterized by an energy E and a momentum \hbar k which are
related through their dispersion E_k. The coupling of two excitations may lead
to abrupt changes (kinks) in the slope of the dispersion. Such kinks thus carry
important information about interactions in a many-body system. For example,
kinks detected at 40-70 meV below the Fermi level in the electronic dispersion
of high-temperature superconductors are taken as evidence for phonon or
spin-fluctuation based pairing mechanisms. Kinks in the electronic dispersion
at binding energies ranging from 30 to 800 meV are also found in various other
metals posing questions about their origins. Here we report a novel, purely
electronic mechanism yielding kinks in the electron dispersions. It applies to
strongly correlated metals whose spectral function shows well separated Hubbard
subbands and central peak as, for example, in transition metal-oxides. The
position of the kinks and the energy range of validity of Fermi-liquid (FL)
theory is determined solely by the FL renormalization factor and the bare,
uncorrelated band structure. Angle-resolved photoemission spectroscopy (ARPES)
experiments at binding energies outside the FL regime can thus provide new,
previously unexpected information about strongly correlated electronic systems.Comment: 8 pages, 5 figure
Multi-layer scintillation detector for the MOON double beta decay experiment: Scintillation photon responses studied by a prototype detector MOON-1
An ensemble of multi-layer scintillators is discussed as an option of the
high-sensitivity detector Mo Observatory Of Neutrinos (MOON) for spectroscopic
measurements of neutrino-less double beta decays. A prototype detector MOON-1,
which consists of 6 layer plastic-scintillator plates, was built to study the
sensitivity of the MOON-type detector. The scintillation photon collection and
the energy resolution, which are key elements for the high-sensitivity
experiments, are found to be 1835+/-30 photo-electrons for 976 keV electrons
and sigma = 2.9+/-0.1% (dE/E = 6.8+/-0.3 % in FWHM) at the Qbb ~ 3 MeV region,
respectively. The multi-layer plastic-scintillator structure with good energy
resolution as well as good background suppression of beta-gamma rays is crucial
for the MOON-type detector to achieve the inverted hierarchy neutrino mass
sensitivity.Comment: 8 pages, 16 figures, submitted to Nucl.Instrum.Met
Predictors of tropical cyclone-induced urban tree failure: an international scoping review
Background: Trees are critical components of rural and urban ecosystems throughout the world. While they have adapted to the historic conditions of their native environments, climate change, urbanization, and human-assisted range expansion may test the storm resiliency of many tree species.
Objective: In this global multilingual scoping review, we investigate a range of intrinsic (i.e., tree characteristics) and external (i.e., environmental and management) factors which have been used to predict tree failure during tropical cyclones.
Design: We searched online databases and journals in English, Chinese, French, Japanese, Portuguese, and Spanish to find peer-reviewed papers and dissertations. We retained papers that used ground-based methods to study tree damage following a tropical cyclone and conducted a statistical analysis of factors that influence tree resistance to damage. From each paper we extracted details of study methods, and the relationships between damage and predictors.
Results: Our efforts generated 65 peer-reviewed papers and dissertations that met our final criteria for inclusion (i.e., data on the relative proportion of trees failed/intact as assessed no more than a year after the storm event). Of these papers 37 independent variables were assessed to predict tree failure. Research in both urban and rural settings tends to be concentrated in regions frequently impacted by tropical cyclones. Characteristics of species such as wood density have been studied in rural environments and are also relevant predictors for tree failure in urban trees. Environmental characteristics unique to urban settings such as planting areas surrounded by pavement need further research. Several urban studies demonstrate that risk assessment methods can predict tree failure during a storm.
Conclusion: Results can be used by future storm researchers to identify both predictors may warrant inclusion in their models as well as predictors which have yet to be tested. Results can also inform planning and activities that can mitigate tropical cyclone damage to the urban forest
Effects of work burden, job strain and support on depressive symptoms and burnout among Japanese physicians
ESPEN guidelines on definitions and terminology of clinical nutrition
BACKGROUND:
A lack of agreement on definitions and terminology used for nutrition-related concepts and procedures limits the development of clinical nutrition practice and research.
OBJECTIVE:
This initiative aimed to reach a consensus for terminology for core nutritional concepts and procedures.
METHODS:
The European Society of Clinical Nutrition and Metabolism (ESPEN) appointed a consensus group of clinical scientists to perform a modified Delphi process that encompassed e-mail communication, face-to-face meetings, in-group ballots and an electronic ESPEN membership Delphi round.
RESULTS:
Five key areas related to clinical nutrition were identified: concepts; procedures; organisation; delivery; and products. One core concept of clinical nutrition is malnutrition/undernutrition, which includes disease-related malnutrition (DRM) with (eq. cachexia) and without inflammation, and malnutrition/undernutrition without disease, e.g. hunger-related malnutrition. Over-nutrition (overweight and obesity) is another core concept. Sarcopenia and frailty were agreed to be separate conditions often associated with malnutrition. Examples of nutritional procedures identified include screening for subjects at nutritional risk followed by a complete nutritional assessment. Hospital and care facility catering are the basic organizational forms for providing nutrition. Oral nutritional supplementation is the preferred way of nutrition therapy but if inadequate then other forms of medical nutrition therapy, i.e. enteral tube feeding and parenteral (intravenous) nutrition, becomes the major way of nutrient delivery.
CONCLUSION:
An agreement of basic nutritional terminology to be used in clinical practice, research, and the ESPEN guideline developments has been established. This terminology consensus may help to support future global consensus efforts and updates of classification systems such as the International Classification of Disease (ICD). The continuous growth of knowledge in all areas addressed in this statement will provide the foundation for future revisions
An inverse association between West Nile virus serostatus and avian malaria infection status
BACKGROUND: Various ecological and physiological mechanisms might influence the probability that two or more pathogens may simultaneously or sequentially infect a host individual. Concurrent infections can have important consequences for host condition and fitness, including elevated mortality risks. In addition, interactions between coinfecting pathogens may have important implications for transmission dynamics. METHODS: Here, we explore patterns of association between two common avian pathogens (West Nile virus and avian malaria parasites) among a suburban bird community in Chicago, IL, USA that share mosquito vectors. We surveyed 1714 individual birds across 13 species for both pathogens through established molecular protocols. RESULTS: Field investigations of haemosporidian and West Nile virus (WNV) infections among sampled birds yielded an inverse association between WNV serostatus and Plasmodium infection status. This relationship occurred in adult birds but not in juveniles. There was no evidence for a relationship between Haemoproteus infection and WNV serostatus. We detected similar prevalence of Plasmodium among birds captured with active WNV infections and spatiotemporally paired WNV-naïve individuals of the same species, demonstrating that the two pathogens can co-infect hosts. CONCLUSIONS: Mechanisms explaining the negative association between WNV serostatus and Plasmodium infection status remain unclear and must be resolved through experimental infection procedures. However, our results highlight potential interactions between two common avian pathogens that may influence their transmission among hosts. This is especially relevant considering that West Nile virus is a common zoonotic pathogen with public health implications. Moreover, both pathogens are instructive models in infectious disease ecology, and infection with either has fitness consequences for their avian hosts. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/1756-3305-7-415) contains supplementary material, which is available to authorized users
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