382 research outputs found
Stability of resilience in times of the COVIDâ19 pandemic
There is disagreement among researchers regarding the conceptualization of resilience as a dynamic state or stable trait. Aiming to shed light on the state-versus-trait debate, we explored the stability and construct validity of four of the most frequently utilized state or trait resilience scales in a longitudinal assessment. Additionally, we examined the predictive validity of these scales. Our study was conducted before and during the COVID-19 pandemic, which served as collectively experienced adversity. Correlations among the resilience scales and among resilience scales and Big Five personality traits were strong. All except one scale showed high test-retest correlations. Experience of an additional critical life event during the pandemic led to an increase in resilience. Other than in cross-sectional studies, associations between resilience and psychological distress were weak, because personality and baseline psychological distress were controlled for. Nevertheless, next to personality, resilience explained additional variance in distress change. Our results show relatively high stability of resilience overall. Yet, they also confirm dynamic resilience features, suggesting that resilience change occurs with significant adversity, leading to improved adaptation. To gauge the true association between resilience and mental health, baseline levels of these variables as well as personality traits should be considered
Resilience and personality as predictors of the biological stress load during the first wave of the Covid-19 pandemic in Germany
Since the Covid-19 outbreak, pandemic-specific stressors have potentiated the-already severe-stress load across the world. However, stress is more than an adverse state, and chronic exposure is causally involved in the development of mental and physical disease. We ask the question whether resilience and the Big Five personality traits predict the biological stress response to the first lockdown in Germany. In a prospective, longitudinal, observational study, N = 80 adult volunteers completed an internet-based survey prior to the first Covid-19-related fatality in Germany (T0), during the first lockdown period (T1), and during the subsequent period of contact restrictions (T2). Hair strands for the assessment of systemic cortisol and cortisone levels were collected at T2. Higher neuroticism predicted higher hair cortisol, cortisone and subjective stress levels. Higher extraversion predicted higher hair cortisone levels. Resilience showed no effects on subjective or physiological stress markers. Our study provides longitudinal evidence that neuroticism and extraversion have predictive utility for the accumulation of biological stress over the course of the pandemic. While in pre-pandemic times individuals high in neuroticism are typically at risk for worse health outcomes, extraverted individuals tend to be protected. We conclude that, in the pandemic context, we cannot simply generalize from pre-pandemic knowledge. Neurotic individuals may currently suffer due to their general emotional lability. Extraverted individuals may primarily be socially stressed. Individualized stress management programs need to be developed, and offered in a lockdown-friendly format, to minimize the stress burden caused by Covid-19 or future pandemics and to protect the most severely affected individuals from the development of stress-associated disease
BIOCONTROL OF PHYTOPHTHORA CINNAMOMI ON AVOCADO: IDENTIFICATION AND FIELD TESTING OF LOCAL NATURAL ANTAGONISTS, AND EVALUATION OF ROOTSTOCKS FOR RESISTANCE
Abstract Soils suppressive to root rot of avocado (caused by Phytophthora cinnamomi), were first identified in South Africa in 1990. Mcro-organisms from these soils were tested for in vitro antagonism to Phytophthora cinnamomi and subsequently evaluated for suppression of root rot of avocado seedling plants in a mistbed. Three fungal antagonists, Paecilomyces filacinus, Aspergillus candidus and Trichoderma hamatum were effective in suppressing root rot. These antagonists have been evaluated since 1992 for control of root rot in avocado trees in the field. Populations of the antagonists have been found to increase in the root zone of newly planted trees (after antagonist treatment in the nursery and in the orchard) and in the root zone of established Hass and Fuerte trees planted in 1981 and 1980 (after antagonist treatment in the orchard). In an isolated planting site consisting of various ungrafted avocado rootstocks (eg. G1033, Dusa, Latas, D9, Duke 7, Barr Duke, Thomas, Velvic) trees undergo open pollination. Seeds from this orchard, situated at Westfalia Estate, are germinated and the seedlings evaluated for resistance to root rot in a mistbed. A number of successful selections have been made and these are being clonally propagated and grafted with Hass. These trees are to be planted in a root rot infested field site where they will be evaluated for yield and resistance to root rot
The -boundedness of a family of integral operators on UMD Banach function spaces
We prove the -boundedness of a family of integral operators with an
operator-valued kernel on UMD Banach function spaces. This generalizes and
simplifies earlier work by Gallarati, Veraar and the author, where the
-boundedness of this family of integral operators was shown on Lebesgue
spaces. The proof is based on a characterization of -boundedness as
weighted boundedness by Rubio de Francia.Comment: 13 pages. Generalization of arXiv:1410.665
FACT -- The G-APD revolution in Cherenkov astronomy
Since two years, the FACT telescope is operating on the Canary Island of La
Palma. Apart from its purpose to serve as a monitoring facility for the
brightest TeV blazars, it was built as a major step to establish solid state
photon counters as detectors in Cherenkov astronomy. The camera of the First
G-APD Cherenkov Telesope comprises 1440 Geiger-mode avalanche photo diodes
(G-APD), equipped with solid light guides to increase the effective light
collection area of each sensor. Since no sense-line is available, a special
challenge is to keep the applied voltage stable although the current drawn by
the G-APD depends on the flux of night-sky background photons significantly
varying with ambient light conditions. Methods have been developed to keep the
temperature and voltage dependent response of the G-APDs stable during
operation. As a cross-check, dark count spectra with high statistics have been
taken under different environmental conditions. In this presentation, the
project, the developed methods and the experience from two years of operation
of the first G-APD based camera in Cherenkov astronomy under changing
environmental conditions will be presented.Comment: Proceedings of the Nuclear Science Symposium and Medical Imaging
Conference (IEEE-NSS/MIC), 201
FACT -- the First Cherenkov Telescope using a G-APD Camera for TeV Gamma-ray Astronomy (HEAD 2010)
Geiger-mode Avalanche Photodiodes (G-APD) bear the potential to significantly
improve the sensitivity of Imaging Air Cherenkov Telescopes (IACT). We are
currently building the First G-APD Cherenkov Telescope (FACT) by refurbishing
an old IACT with a mirror area of 9.5 square meters and construct a new, fine
pixelized camera using novel G-APDs. The main goal is to evaluate the
performance of a complete system by observing very high energy gamma-rays from
the Crab Nebula. This is an important field test to check the feasibility of
G-APD-based cameras to replace at some time the PMT-based cameras of planned
future IACTs like AGIS and CTA. In this article, we present the basic design of
such a camera as well as some important details to be taken into account.Comment: Poster shown at HEAD 2010, Big Island, Hawaii, March 1-4, 201
Maximal regularity for non-autonomous equations with measurable dependence on time
In this paper we study maximal -regularity for evolution equations with
time-dependent operators . We merely assume a measurable dependence on time.
In the first part of the paper we present a new sufficient condition for the
-boundedness of a class of vector-valued singular integrals which does not
rely on H\"ormander conditions in the time variable. This is then used to
develop an abstract operator-theoretic approach to maximal regularity.
The results are applied to the case of -th order elliptic operators
with time and space-dependent coefficients. Here the highest order coefficients
are assumed to be measurable in time and continuous in the space variables.
This results in an -theory for such equations for .
In the final section we extend a well-posedness result for quasilinear
equations to the time-dependent setting. Here we give an example of a nonlinear
parabolic PDE to which the result can be applied.Comment: Application to a quasilinear equation added. Accepted for publication
in Potential Analysi
The sharp-interface limit for the Navier--Stokes--Korteweg equations
We investigate the sharp-interface limit for the Navier--Stokes--Korteweg model, which is an extension of the compressible Navier--Stokes equations. By means of compactness arguments, we show that solutions of the Navier--Stokes--Korteweg equations converge to solutions of a physically meaningful free-boundary problem. Assuming that an associated energy functional converges in a suitable sense, we obtain the sharp-interface limit at the level of weak solutions
Lateral Distribution of Muons in IceCube Cosmic Ray Events
In cosmic ray air showers, the muon lateral separation from the center of the
shower is a measure of the transverse momentum that the muon parent acquired in
the cosmic ray interaction. IceCube has observed cosmic ray interactions that
produce muons laterally separated by up to 400 m from the shower core, a factor
of 6 larger distance than previous measurements. These muons originate in high
pT (> 2 GeV/c) interactions from the incident cosmic ray, or high-energy
secondary interactions. The separation distribution shows a transition to a
power law at large values, indicating the presence of a hard pT component that
can be described by perturbative quantum chromodynamics. However, the rates and
the zenith angle distributions of these events are not well reproduced with the
cosmic ray models tested here, even those that include charm interactions. This
discrepancy may be explained by a larger fraction of kaons and charmed
particles than is currently incorporated in the simulations
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