1,380 research outputs found
A Semi-analytic Study of Axial Perturbations of Ultra Compact Stars
Compact object perturbations, at linear order, often lead in solving one or
more coupled wave equations. The study of these equations was typically done by
numerical or semi-analytical methods. The WKB method and the associated
Bohr-Sommerfeld rule have been proved extremely useful tools in the study of
black-hole perturbations and the estimation of the related quasi-normal modes.
Here we present an extension of the aforementioned semi-analytic methods in the
study of perturbations of ultra-compact stars and gravastars.Comment: Accepted for publication in CQG, 13 pages, 3 figures, 5 table
Bundesweite Auswertung 2003 der Sortenversuche Wintergerste, Winterweizen und Dinkel der verschiedenen Versuchsansteller im ökologischen Landbau
Deutschlandweite Auswertung der Sortenversuche Wintergerste, Winterweizen und Dinkel (Text und Tabellen)
Tabellen:
- Standortdaten
- Erträge relativ (Winterweizen und Dinkel)
- Rohproteingehalt (Winterweizen und Dinkel)
- Rohproteinmenge (Winterweizen und Dinkel)
- Feuchtklebergehalt (Winterweizen und Dinkel)
- Sedimentationswert (Winterweizen und Dinkel
Parameter estimation of gravitational wave echoes from exotic compact objects
Relativistic ultracompact objects without an event horizon may be able to
form in nature and merge as binary systems, mimicking the coalescence of
ordinary black holes. The postmerger phase of such processes presents
characteristic signatures, which appear as repeated pulses within the emitted
gravitational waveform, i.e., echoes with variable amplitudes and frequencies.
Future detections of these signals can shed new light on the existence of
horizonless geometries, and provide new information on the nature of gravity in
a genuine strong-field regime. In this work we analyze phenomenological
templates used to characterize echolike structures produced by exotic compact
objects, and we investigate for the first time the ability of current and
future interferometers to constrain their parameters. Using different models
with an increasing level of accuracy, we determine the features that can be
measured with the largest precision, and we span the parameter space to find
the most favorable configurations to be detected. Our analysis shows that
current detectors may already be able to extract all the parameters of the
echoes with good accuracy, and that multiple interferometers can measure
frequencies and damping factors of the signals at the level of percent.Comment: References update
The influence of a computerized social cognitive training on the functional connectivity of the brain in major depressive disorder.
Background Cognitive impairment is common in major depressive disorder (MDD)
1,2 and
influences multiple domains of daily living such as maintaining relationships or work
performance 3
. A promising approach that demonstrated an effect on cognitive deficits is
computerized cognitive training (CCT) 1,4. This therapy method induces neuroplastic changes
in the brain representational system of cognitive and emotional processes to reduce cognitive
impairment and reach functional recovery 1,5,6
. The exercises of CCT focus on early perceptual
processes, whereby the processing of socially relevant stimuli is on the forefront in social
cognitive training (SCT) interventions 6-8
. However, treatment response to CCT varies between
the participants, and current research shifted the attention towards the identification of
behavioral and neural markers to measure the target engagement and to predict future
outcome 6
. Preliminary results now suggest the individual sensory processing behavior as a
potential marker for target engagement and treatment response to CCT 9,10
.
Aims In this randomized controlled trial (RCT) we examined the effect of a computerized SCT
on (1) the cognitive performance and psychosocial functioning (2) the rsFC of a priori selected
brain regions (dorsolateral prefrontal cortex [dlPFC], caudate nucleus and amygdala) and the
rest of the brain and (3) the relationship between the change in the cognitive performance and
the rsFC as compared to TAU. We were further interested in the role of distinct patterns of
sensory processing behavior and therefore analyzed the effect of a SCT on (1) the cognitive
performance and psychosocial functioning (2) the rsFC of a priori selected brain regions
(dlPFC, caudate nucleus and amygdala) and the rest of the brain and (3) the relationship
between the change in the cognitive performance and the rsFC between groups with diverging
sensory processing behavior.
Methods Participants were screened for MDD with the SCID-IV. Included subjects (n=40)
underwent a standardized clinical and cognitive assessment and a neuroimaging scan and
were then randomized to the SCT or the TAU group. Participants in the former received a ten
hours computerized SCT over four to six weeks additional to TAU. At the end of the study,
both the clinical and the cognitive assessment and the neuroimaging scan were replicated,
and participants in the SCT group were additionally classified as Maintainers (perceived
baseline sensory processing efficiency) or Improvers (impaired baseline sensory processing
efficiency) depending on the individual performance in the EMT. To examine group differences
between (1) the SCT and the TAU group and (2) Maintainers and Improvers on the cognitive
performance and psychosocial functioning from baseline to follow-up, we used an analysis of
covariance (ANCOVA). Correlation maps of the rsFC between the a priori selected brain
regions (dlPFC, caudate nucleus and amygdala) and the rest of the brain were further
15
calculated with SPM-12 to investigate (1) the effect of the SCT on the rsFC of MDD patients
as compared to TAU and (2) the effect of the SCT on the rsFC of Maintainers and Improvers
across the study. Lastly, Pearsons’s correlation tests were performed to analyze the
association between the change in the rsFC and the cognitive performance in each group.
Results SCT did not show an additional effect on cognition or psychosocial functioning
as compared to TAU in this study. However, Maintainers exhibited significantly higher scores
on social cognition at baseline (F = 1.72; p = 0.05) while Improvers enhanced the sensory
processing efficiency and showed significantly increased social cognitive abilities across the
study (F = 7.78; p = 0.01; η
2
G = 0.34). Moreover, Maintainers showed significantly more benefit
on a social functioning score (GF-S: F = 5.42; p = 0.03; η
2
G = 0.27). On the neural level, we
found a significant increase of the rsFC between the right caudate and the left superior
temporal lobe (STL) (p-corr. = <0.01) in the SCT group compared to TAU across the study. On
the contrary, participants in the TAU group exhibited a significantly enhanced rsFC between
the right caudate and the bilateral superior frontal lobe (SFL) (right SFL: p-corr. = 0.04; left
SFL: p-corr. = < 0.01) as well as between the right dlPFC and the left medial cingulum (p-corr.
= <0.01) and the right precuneus (p-corr. = 0.02) compared to SCT over the follow-up period.
We further identified a significant group by time interaction on the rsFC between the left
amygdala and the left SFL (p-corr. = < 0.01) and the left medial frontal lobe (MFL) (p-corr.=
<0.01) in the Improvers group compared to Maintainers. Likewise, the rsFC between the left
Amygdala and the left MFL (p-corr. = < 0.01) was significantly increased in the Maintainers
group compared to Improvers across the study. There was neither a significant correlation
between the cognitive and the neural changes in 1) the SCT and the TAU group nor 2)
Maintainers and Improvers.
Conclusion The results of our study indicate that the effect of SCT on cognition and
psychosocial functioning probably depends on individual characteristics of the participants
whereby the sensory processing efficiency might be one of the mediators of therapy response.
Consecutively, individuals with reduced sensory processing efficiency, who additionally
presented impaired baseline cognitive functions, seem to benefit more clearly from SCT.
Hereinafter the individual sensory processing efficiency might serve as a behavioral measure
of target engagement to predict the treatment response to SCT. On the neural level, increased
rsFC between neural structures that are integrated in the processing of emotional stimuli
underline the potential of SCT to induce neuroplastic changes in the brain. Since we
additionally identified altered rsFC between distributed brain regions in the TAU group over the
follow-up period, further studies are needed to precisely identify the neuroplastic mechanism
underlying SCT. However, the reorganization of fronto-limbic pathways, which plays an
important role in the pathophysiology of depression 11
, might be an appropriate neural target
16
for cognitive training interventions. Finally, future studies on the relation of cognitive and neural
changes after SCT in depression are needed
Sortenversuche 2002 im ökologischen Landbau in Deutschland: Winterweizen - Bundesweite Auswertung der Ergebnisse der Arbeitsgruppe Ökologischer Versuchsansteller
Deutschlandweite Auswertung der Sortenversuche Winterweizen (Text und Tabellen)
Tabellen:
- Standortdaten
- Zusammenfassung der wichtigsten und auf den meisten Standorten geprĂĽften Sorten
- Erträge relativ bezogen auf die jeweiligen Standortleistungen der Verechnungssorten (VRS)
- % Rohprotein, Sedimentationswert,% Feuchtkleber, relativ bezogen auf die jeweiligen Standortleistungen der Verechnungssorten (VRS)
- Qualitätsmerkmale ausgewählter Winterweizensorten
- Adressen der Versuchsansteller im ökologischen Landba
- …