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Decreased levels of polyunsaturated membrane fatty acids (PUFA) and increased activity of cytosolic phospholipase A2 (PLA2) enzymes (key regulating enzymes of membrane remodelling and PUFA availability) are supporting pillars of the “membrane phospholipids concept of schizophrenia”. Assuming that membrane PUFA profile and PLA2 activity are altered during the at risk phase of disorder and influenced by fatty acid supplementation, we investigated PUFA profiles and PLA2 activity simultaneously in ultra high-risk (UHR) subjects before and after (n-3) fatty acids supplementation.
In 81 UHR patients (aged between 13 and 25 years) PUFA levels were assessed in erythrocyte membranes using gas chromatography, and cytosolic PLA2 activity was measured in blood serum using a fluorometric HPTLC-based assay. Measurements were performed before and after a 6 month interval of placebo-controlled supplementation with n-3 fatty acids.
At baseline significant associations were found between (n-9) and (n-6)-PUFA levels and psychopathology (especially in negative symptoms) assessed by the PANSS according to PACE criteria. (n-3)-PUFA supplementation caused significant changes in (n-3)- and (n-6)-PUFA levels and a significant decrease of PLA2 activity.
Our results support associations between membrane biochemistry and psychopathology (especially negative symptoms) in people at risk to develop psychosis. Supplementation of n-3 PUFA increases PUFA availability at membrane level and modulates membrane repair and remodelling processes. Assuming that PLA2 activity reflects neuronal damage, PUFA supplementation might unfold neuroprotective effects.
Permafrost occupies 20 million square kilometres of Earth’s high-latitude and high-altitude landscapes. These regions are sensitive to climate change and human activities; hence, permafrost research is of considerable scientific and societal importance. However, the results of this research are generally not known by the general public. Communicating scientific concepts is an increasingly important task in the research world. Different ways to engage learners and incorporate narratives in teaching materials exist, yet they are generally underused. Here we report on an international scientific outreach project called “Frozen-Ground Cartoons”, which aims at making permafrost science accessible and fun for students, teachers, and parents through the creation of comic strips. We present the context in which the project was initiated, as well as recent education and outreach activities. The future phases of the project primarily involve a series of augmented reality materials, such as maps, photos, videos, and 3D drawings. With this project we aim to foster understanding of permafrost research among broader audiences, inspire future permafrost researchers, and raise public and science community awareness of polar science, education, outreach, and engagement.
Political science takes pride in objective and methodologically rigorous research. This should be reflected in a clear and concise writing style that convinces readers by the content of the research, not by the language used to report about it. This article demonstrates that this is true but only to a limited extent. It shows that—similar to recent findings from natural-sciences research—the frequency of positive words that political scientists use to describe their research has increased markedly in recent decades. At the same time, however, the magnitude of this increase is much less pronounced. The article discusses and analyzes potential explanations for this trend. We suspect that it can be attributed at least partly to changing norms in the discipline, in which research framed in a positive way is more likely to be published.
Counter-propagating and suitably polarized light (laser) beams can provide conditions for pair production. Here, we consider in more detail the following two situations: (i) in the homogeneity regions of anti-nodes of linearly polarized ultra-high intensity laser beams, the Schwinger process is dynamically assisted by a second high-frequency field, e.g. by an XFEL beam; and (ii) a high-energy probe photon beam colliding with a superposition of co-propagating intense laser and XFEL beams gives rise to the laser-assisted Breit–Wheeler process. The prospects of such bi-frequent field constellations with respect to the feasibility of conversion of light into matter are discussed.
Reconstruction with a vascularised flap provides the most reliable outcome, with post-operative cerebrospinal fluid leak rates of less than 5 per cent. This article aims to review and summarise the critical technical aspects of the vascularised flaps most commonly used for skull base reconstruction.
Vascularised flaps are classified as intranasal or extranasal. The intranasal group includes the Hadad–Bassagaisteguy nasoseptal flap, the Caicedo reverse nasoseptal flap, the nasoseptal rescue flap, the posteriorly or anteriorly based lateral wall flaps, and the middle turbinate flap. Extranasal flaps include the transfrontal pericranial and transpterygoid temporoparietal flaps.
The Hadad–Bassagaisteguy nasoseptal flap is overwhelmingly favoured for reconstructing extensive defects of anterior, middle and posterior cranial base. Its pertinent technical features are described. However, it is essential to master the skills required for the various extranasal or regional vascularised flaps because each can offer a reconstructive alternative for specific patients, especially when open approaches are needed and/or intranasal vascularised flaps are not feasible.
Here we present an alternative approach to coarse graining, based on the multiresolution diffusion-wavelet approach to operator compression, which does not require explicit atomistic-to-coarse-grained mappings. Our diffusion-wavelet method takes as input the topology and sparsity of the molecular bonding structure of a system, and returns as output a hierarchical set of degrees of freedom (DoFs) of system-specific coarse-grained variables. Importantly, the hierarchical compression provides a clear framework for modeling at many model scales (levels), beyond the common two-level CG representation. Our results show that the resulting hierarchy separates localized modes, such as a single C-C vibrational mode, from larger-scale motions, e.g., long-range concerted backbone vibrational modes. Our approach correctly captures small-scale chemical features, such as cellulose ring structures, and alkane side chains or CH2 units, as well as large-scale features of the backbone. In particular, the new method’s finest-scale modes describe DoFs similar to united atom models and other chemically-defined CG models. Modes at coarser levels describe increasingly large connected portions of the target polymers. For polyethylene and polystyrene, spatial coordinates and their associated forces were compressed by up to two orders of magnitude. The compression in forces is of particular interest as this allows larger timesteps as well as reducing the number of DoFs.
In this work we introduce an optimization–based method for the coupling of nonlocal and local diffusion problems. Our approach is formulated as a control problem where the states are the solutions of the nonlocal and local equations, the controls are the nonlocal volume constraint and the local boundary condition, and the objective of the optimization is a matching functional for the state variables in the intersection of the nonlocal and local domains. For finite element discretizations we present numerical results in a one–dimensional setting; though preliminary, our tests show the consistency and efficacy of the method, and provide the basis for realistic simulations.
Cognitive models focus on information and the computational manipulation of information. Rational models optimize the function that relates the input of a process to the output. In contrast, efficient algorithms minimize the computational cost of processing in terms of time. Minimizing time is a better criterion for normative models, because it reflects the energy costs of a physical system.
Scores on the Boston Naming Test (BNT) are frequently lower for African American when compared with Caucasian adults. Although demographically based norms can mitigate the impact of this discrepancy on the likelihood of erroneous diagnostic impressions, a growing consensus suggests that group norms do not sufficiently address or advance our understanding of the underlying psychometric and sociocultural factors that lead to between-group score discrepancies. Using item response theory and methods to detect differential item functioning (DIF), the current investigation moves beyond comparisons of the summed total score to examine whether the conditional probability of responding correctly to individual BNT items differs between African American and Caucasian adults. Participants included 670 adults age 52 and older who took part in Mayo’s Older Americans and Older African Americans Normative Studies. Under a two-parameter logistic item response theory framework and after correction for the false discovery rate, 12 items where shown to demonstrate DIF. Of these 12 items, 6 (“dominoes,” “escalator,” “muzzle,” “latch,” “tripod,” and “palette”) were also identified in additional analyses using hierarchical logistic regression models and represent the strongest evidence for race/ethnicity-based DIF. These findings afford a finer characterization of the psychometric properties of the BNT and expand our understanding of between-group performance. (JINS, 2009, 15, 758–768.)
In this study, we attempted a molecular characterization of the 5S rDNA in two closely related species of carcharhiniform sharks, Rhizoprionodon lalandii and Rhizoprionodon porosus, as well as a further comparative analysis of available data on lampreys, several fish groups and other vertebrates. Our data show that Rhizoprionodon sharks carry two 5S rDNA classes in their genomes: a short repeat class (termed class I) composed of ~185 bp repeats, and a large repeat class (termed class II) arrayed in ~465 bp units. These classes were differentiated by several base substitutions in the 5S coding region and by completely distinct non-transcribed spacers (NTS). In class II, both species showed a similar composition for both the gene coding region and the NTS region. In contrast, class I varied extensively both within and between the two shark species. A comparative analysis of 5S rRNA gene sequences of elasmobranchs and other vertebrates showed that class I is closely related to the bony fishes, whereas the class II gene formed a separate cartilaginous clade. The presence of two variant classes of 5S rDNA in sharks likely maintains the tendency for dual ribosomal classes observed in other fish species. The present data regarding the 5S rDNA organization provide insights into the dynamics and evolution of this multigene family in the fish genome, and they may also be useful in clarifying aspects of vertebrate genome evolution.
A central role for neuropsychological evaluations is the measurement
of change in cognitive functioning over time. However, change scores
obtained from repeated neuropsychological assessments may be affected by
normal variability because of measurement error and practice effects
caused by repeated measurements. The current study uses reliable change
estimates to establish normative rates of change on the Dementia Rating
Scale from baseline to first follow-up testing among 1080 cognitively
normal adults aged 65 and older. Results showed that a 6-point decline by
European Americans or a 9-point decline by African American adults within
a 9–15 month test-retest interval represents reliable change. Within
a 16–24-month test-retest interval, a 7-point decline among European
Americans or an 8-point decline among African American adults represents
reliable change. In addition, preliminary cross-validation was performed
in a clinical comparison sample of another 22 older adults. The findings
are discussed in the context of potential clinical and research
applications. (JINS, 2007, 13, 716–720.)
Acupuncture has been claimed to be associated with activation of the endogenous antinociceptive system. The analgesic effects of acupuncture have been ascribed to β-endorphin interacting with opioid receptors. However, firstly, the release of β-endorphin into the blood has been proven to be induced by stress, i.e. under dysphoric conditions, and, secondly, if released under stress, β-endorphin has been shown not to be analgesic. Our aim was to test whether β-endorphin immunoreactive material is released into the cardiovascular compartment during acupuncture comparing the most frequently used types of acupuncture with standard pain treatment under apparently low stress conditions.
This prospective study included 15 male patients suffering from chronic low back pain. β-Endorphin immunoreactive material and cortisol were measured in the plasma of patients who underwent, in randomorder, therapy according to a standard pain treatment, traditional Chinese acupuncture, sham acupuncture, electro acupuncture and electro acupuncture at non-acupuncture points before, at and after the treatment. Statistical analysis was performed using two-way ANOVA with repeated measures.
A decrease in plasma cortisol concentration measured over the five treatment protocols was highly significant (P < 0.001). The β-endorphin immunoreactive material concentrations in plasma were minimal at all times and in all treatment conditions. The influence of treatments by various acupuncture procedures on cortisol and β-endorphin immunoreactive material plasma concentrations over the three time points was not significantly different.
β-endorphin immunoreactive material in blood is not released by any type of acupuncture as tested under low stress conditions.
The impact of anxiety disorders has not been well delineated in prospective studies of bipolar disorder.
To examine the association between anxiety and course of bipolar disorder, as defined by mood episodes, quality of life and role functioning.
A thousand out-patients with bipolar disorder were followed prospectively for 1 year.
A current comorbid anxiety disorder (present in 31.9% of participants) was associated with fewer days well, a lower likelihood of timely recovery from depression, risk of earlier relapse, lower quality of life and diminished role function over 1 year of prospective study. The negative impact was greater with multiple anxiety disorders.
Anxiety disorders, including those present during relative euthymia, predicted a poorer bipolar course. The detrimental effects of anxiety were not simply a feature of mood state. Treatment studies targeting anxiety disorders will help to clarify the nature of the impact of anxiety on bipolar course.
Our aim was to analyze left ventricular fractional shortening during extracorporeal membrane oxygenation under the influence of changing volume loading conditions induced by a ductal left-to-right shunt. In all patients, the fractional shortening was observed using echocardiography before, during, and after bypass, irrespective of the presence or absence of the ductal left-to-right shunt. During membrane oxygenation, there was a significant decrease in fractional shortening (p less than 0.001), with no difference before and after membrane oxygenation. A greater decrease in fractional shortening was observed in the group with a ductal left-to-right shunt when compared to patients lacking the ductal shunt (p less than 0.006). The diastolic diameter of the left ventricle also increased significantly during the membrane oxygenation in those patients with left-to-right ductal shunting. Moreover, the patients with left-to-right shunting showed a very severe decreased fractional shortening, lower than 10 per cent, with significantly greater frequency (p less than 0.05) during the course of membrane oxygenation. Conclusion: An important decrease in left ventricular fractional shortening is observed during veno-arterial extracorporeal membrane oxygenation. Left-to-right shunting during bypass, as seen in the patients with patency of the arterial duct, increases the loading conditions on the left ventricle, and produces a significant increase in left ventricular diastolic dimensions. Despite the effects of volume loading produced by the ductal shunt during bypass, the decrease in fractional shortening is significantly more pronounced for these patients. Therefore, during membrane oxygenation the volume loading produced by the ductal shunt is unable to prevent a decrease in left ventricular fractional shortening.
Covariance structure analyses of a core neuropsychological test
battery consisting of the Wechsler Adult Intelligence Scale–Revised,
Wechsler Memory Scale–Revised, and Auditory Verbal Learning Test
have previously identified a 5-factor model in a sample of cognitively
normal White volunteers from Mayo's Older Americans Normative Studies
(MOANS). The present study sought to replicate this factor structure in a
sample of 289 cognitively normal, community-dwelling African American
elders from Mayo's Older African Americans Normative Studies
(MOAANS). The original 5-factor model was tested against 2 alternative
4-factor models and a 6-factor model generated on a substantive basis.
Confirmatory factor analysis supported the construct validity of this core
battery in older African Americans by replicating the original 5-factor
model of Verbal Comprehension, Perceptual Organization,
Attention/Concentration, Learning, and Retention as viable in the
present sample. (JINS, 2005, 11, 184–191.)
Magnetic coupling relates the energy sources below the photosphere to the structure and dynamics of the chromosphere and corona of the Sun. Multi-wavelength investigations of the solar activity provides the information needed to understand the acting physical mechanisms. Descriptions of magnetic coupling often start with force-free mathematical extrapolations of the photospheric magnetic field. Observations have revealed, however, perpendicular electric current sheets, reconnection and other locally non-force-free structures in chromosphere and corona. Obviously, the solar magnetic coupling includes dynamic forcing due to photospheric plasma motion. We developed a model which though it starts with force-free extrapolated observed photospheric magnetic field additionally takes into account the energy input due to the chromospheric neutral gas and plasma motion. We demonstrate the abilities of our model by applying it to SoHO multi-wavelength observations of an EUV bright point (BP).To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html