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What is the climate system able to do ‘on its own’?
The climate of the Earth, like planetary climates in general, is broadly controlled by solar irradiation, planetary albedo and emissivity as well as its rotation rate and distribution of land (with its orography) and oceans. However, the majority of climate fluctuations that affect mankind are internal modes of the general circulation of the atmosphere and the oceans. Some of these modes, such as El Nino-Southern Oscillation (ENSO), are quasi-regular and have some longer-term predictive skill; others like the Arctic and Antarctic Oscillation are chaotic and generally unpredictable beyond a few weeks. Studies using general circulation models indicate that internal processes dominate the regional climate and that some like ENSO events have even distinct global signatures. This is one of the reasons why it is so difficult to separate internal climate processes from external ones caused, for example, by changes in greenhouse gases and solar irradiation. However, the accumulation of the warmest seasons during the latest two decades is lending strong support to the forcing of the greenhouse gases. As models are getting more comprehensive, they show a gradually broader range of internal processes including those on longer time scales, challenging the interpretation of the causes of past and present climate events further
Enhanced Detection of Emotional Facial Expressions in Borderline Personality Disorder
Background: Borderline personality disorder (BPD) is commonly proposed to be
characterized by an enhanced sensitivity for emotional stimuli. In the present
study, we investigated whether BPD patients show a superior detection of
emotional facial expressions relative to healthy controls. The detection of
emotional information in the environment represents an important facet of
emotional sensitivity. Sampling and Methods: Twenty patients with BPD were
compared with 25 healthy controls. The participants were presented a rapid,
continuous stream of neutral and randomly inserted emotional facial
expressions and were asked to report the presentation of an emotional facial
stimulus after each trial. Availability of cognitive resources was manipulated
via two different task demands. Results: The participants with BPD performed
significantly better in the detection of positive and negative facial
expressions compared to the healthy controls. False alarm rates did not differ
significantly between the two groups. Conclusions: The BPD participants showed
an enhanced detection of emotional expressions that might be related to the
emotional disturbances they experience. In particular, we will discuss the
role of this superior emotion detection (in combination with previously
reported deficits in the labeling of emotional states) for the understanding
of emotional instability in BPD
NaV_2O_5 as an Anisotropic t-J Ladder at Quarter Filling
Based on recent experimental evidences that the electronic charge degrees of
freedom plays an essential role in the spin-Peierls--like phase transition of
NaVO, we first make the mapping of low-energy electronic states of the
model for NaVO to the quarter-filled ladder with
anisotropic parameter values between legs and rungs, and then show that this
anisotropic ladder is in the Mott insulating state, of which
lowest-energy states can be modeled by the one-dimensional Heisenberg
antiferromagnet with the effective exchange interaction whose value
is consistent with experimental estimates. We furthermore examine the coupling
between the ladders as the trellis lattice model and show that the
nearest-neighbor Coulomb repulsion on the zigzag-chain bonds can lead to the
instability in the charge degrees of freedom of the ladders.Comment: 4 pages, 5 gif figures. Fig.3 corrected. Hardcopies of figures (or
the entire manuscript) can be obtained by e-mail request to
[email protected]
A Model Study of the Low-Energy Charge Dynamics of NaV_2O_5
An exact-diagonalization technique on small clusters is used to calculate the
dynamical density correlation functions of the dimerized t-J chain and coupled
anisotropic t-J ladders (trellis lattice) at quarter filling, i.e., the systems
regarded as a network of pairs (dimers or rungs) of sites coupled weakly via
the hopping and exchange interactions. We thereby demonstrate that the
intersite Coulomb repulsions between the pairs induce a low-energy collective
mode in the charge excitations of the systems where the internal charge degrees
of freedom of the pairs play an essential role. Implications to the electronic
states of NaV_2O_5, i.e., fluctuations of the valence state of V ions and phase
transition as a charge ordering, are discussed.Comment: 4 pages, 4 gif figures. Hardcopies of figures (or the entire
manuscript) can be obtained by e-mail request to [email protected]
The effect of clouds in a galactic wind on the evolution of gas-rich dwarf galaxies
(Abridged)
We study the effects of interstellar clouds on the dynamical and chemical
evolution of gas-rich dwarf galaxies. In particular, we focus on two model
galaxies similar to IZw18 and NGC1569 in comparison to models in which a smooth
initial distribution of gas is assumed. We use a 2-D hydrodynamical code
coupled with a series of routines able to trace the chemical products of SNeII,
SNeIa and intermediate-mass stars. Clouds are simulated by adding overdense
regions in the computational grid, whose locations are chosen randomly and
whose density profiles match observed ones. The clouds are inherently
dynamically coupled to the diffuse gas, and they experience heat conduction
from a hot surrounding gas. Due to dynamical processes and thermal evaporation,
the clouds survive only a few tens of Myr. Due to the additional cooling agent,
the internal energy of cloudy models is typically reduced by 20 - 40% compared
with models of diffuse gas alone. The clouds delay the development of
large-scale outflows by mass loading, therefore helping to retain a larger
amount of gas inside the galaxy. However, their bullet effect can pierce the
expanding supershell and create holes through which the superbubble can vent
freshly produced metals. Moreover, assuming a pristine chemical composition for
the clouds, their interaction with the superbubble dilutes the gas, reducing
the metallicity. The resulting final metallicity is therefore generally lower
(by ~ 0.2 - 0.4 dex) than the one attained by diffuse models.Comment: 13 pages, 11 figures, A&A accepte
Zigzag Charge Ordering in alpha'-NaV2O5
23Na NMR spectrum measurements in alpha'-NaV2O5 with a single- crystalline
sample are reported. In the charge-ordered phase, the number of inequivalent Na
sites observed is more than that expected from the low-temperature structures
of space group Fmm2 reported so far. This disagreement indicates that the real
structure including both atomic displacement and charge disproportionation is
of lower symmetry. It is suggested that zigzag ordering is the most probable.
The temperature variation of the NMR spectra near the transition temperature is
incompatible with that of second-order transitions. It is thus concluded that
the charge ordering transition is first-order.Comment: 4 pages, 5 eps figures, submitted to J. Phys. Soc. Jp
Using electronic structure changes to map the H-T phase diagram of alpha'-NaV2O5
We report polarized optical reflectance studies of \alpha'-NaV2O5 as a
function of temperature (4-45 K) and magnetic field (0-60 T). Rung directed
electronic structure changes, as measured by near-infrared reflectance ratios
\Delta R(H)=R(H)/R(H=0 T), are especially sensitive to the phase boundaries. We
employ these changes to map out an H-T phase diagram. Topological highlights
include the observation of two phase boundaries slightly below T_{SG}, enhanced
curvature of the 34 K phase boundary above 35 T, and, surprisingly, strong
hysteresis effects of both transitions with applied field.Comment: 4 pages, 3 figures, PRB accepte
Reduced tillage, but not organic matter input, increased nematode diversity and food web stability in European long‐term field experiments
Soil nematode communities and food web indices can inform about the complexity, nutrient flows and decomposition pathways of soil food webs, reflecting soil quality. Relative abundance of nematode feeding and life‐history groups are used for calculating food web indices, i.e., maturity index (MI), enrichment index (EI), structure index (SI) and channel index (CI). Molecular methods to study nematode communities potentially offer advantages compared to traditional methods in terms of resolution, throughput, cost and time. In spite of such advantages, molecular data have not often been adopted so far to assess the effects of soil management on nematode communities and to calculate these food web indices. Here, we used high‐throughput amplicon sequencing to investigate the effects of tillage (conventional vs. reduced) and organic matter addition (low vs. high) on nematode communities and food web indices in 10 European long‐term field experiments and we assessed the relationship between nematode communities and soil parameters. We found that nematode communities were more strongly affected by tillage than by organic matter addition. Compared to conventional tillage, reduced tillage increased nematode diversity (23% higher Shannon diversity index), nematode community stability (12% higher MI), structure (24% higher SI), and the fungal decomposition channel (59% higher CI), and also the number of herbivorous nematodes (70% higher). Total and labile organic carbon, available K and microbial parameters explained nematode community structure. Our findings show that nematode communities are sensitive indicators of soil quality and that molecular profiling of nematode communities has the potential to reveal the effects of soil management on soil quality
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