Organic matter processing and soil evolution in a braided river system

Traditionally, braided river research has considered flow, sediment transport processes and, recently, vegetation dynamics in relation to river morphodynamics. However, if considering the development of woody vegetated patches over a time scale of decades, we must consider the extent to which soil forming processes, particularly related to soil organic matter, impact the alluvial geomorphic-vegetation system. Here we quantify the soil organic matter processing (humification) that occurs on young alluvial landforms. We sampled different geomorphic units, ranging from the active river channel to established river terraces in a braided river system. For each geomorphic unit, soil pits were used to sample sediment/soil layers that were analysed in terms of grain size (<2mm) and organic matter quantity and quality (RockEval method). A principal components analysis was used to identify patterns in the dataset. Results suggest that during the succession from bare river gravels to a terrace soil, there is a transition from small amounts of external organic matter supply provided by sedimentation processes (e.g. organic matter transported in suspension and deposited on bars), to large amounts of autogenic in situ organic matter production due to plant colonisation. This appears to change the time scale and pathways of alluvial succession (bio-geomorphic succession). However, this process is complicated by: the ongoing possibility of local sedimentation, which can serve to isolate surface layers via aggradation from the exogenic supply; and erosion which tends to create fresh deposits upon which organic matter processing must re-start. The result is a complex pattern of organic matter states as well as a general lack of any clear chronosequence within the active river corridor. This state reflects the continual battle between deposition events that can isolate organic matter from the surface, erosion events that can destroy accumulating organic matter and the early ecosystem processes necessary to assist the co-evolution of soil and vegetation. A key question emerges over the extent to which the fresh organic matter deposited in the active zone is capable of significantly transforming the local geochemical environment sufficiently to accelerate soil development.

Working memory in schizophrenia: dynamic visuo-spatial information processing

Working memory, commonly defined as the ability to hold mental representations on line transiently and to manipulate these representations, is known to be a core deficit in schizophrenia. The aim of the present study was to investigate the visuo-spatial component of the working memory in schizophrenia, and more precisely to what extent the dynamic visuo-spatial information processing is impaired in schizophrenia patients. For this purpose we used a computerized paradigm in which 29 patients with schizophrenia (DSMIV, Diagnostic Interview for Genetic Studies) and 29 age and sex matched control subjects (DIGS) had to memorize a plane moving across the computer screen and to identify the observed trajectory among 9 plots proposed together. Each trajectory could be seen max. 3 times if needed. The results showed no difference between schizophrenia patients and controls regarding the number of correct trajectory identified after the first presentation. However, when we determine the mean number of correct trajectories on the basis of 3 trials, we observed that schizophrenia patients are significantly less performant than controls (Mann-Whitney, p _ 0.002). These findings suggest that, although schizophrenia patients are able to memorize some dynamic trajectories as well as controls, they do not profit from the repetition of the trajectory presentation. These findings are congruent with the hypothesis that schizophrenia could induce an unbalance between local and global information processing: the patients may be able to focus on details of the trajectory which could allow them to find the right target (bottom-up processes), but may show difficulty to refer to previous experience in order to filter incoming information (top-down processes) and enhance their visuo-spatial working memory abilities.

In vivo brain macromolecule signals in healthy and glioblastoma mouse models: (1) H magnetic resonance spectroscopy, post-processing and metabolite quantification at 14.1 T.

In (1) H magnetic resonance spectroscopy, macromolecule signals underlay metabolite signals, and knowing their contribution is necessary for reliable metabolite quantification. When macromolecule signals are measured using an inversion-recovery pulse sequence, special care needs to be taken to correctly remove residual metabolite signals to obtain a pure macromolecule spectrum. Furthermore, since a single spectrum is commonly used for quantification in multiple experiments, the impact of potential macromolecule signal variability, because of regional differences or pathologies, on metabolite quantification has to be assessed. In this study, we introduced a novel method to post-process measured macromolecule signals that offers a flexible and robust way of removing residual metabolite signals. This method was applied to investigate regional differences in the mouse brain macromolecule signals that may affect metabolite quantification when not taken into account. However, since no significant differences in metabolite quantification were detected, it was concluded that a single macromolecule spectrum can be generally used for the quantification of healthy mouse brain spectra. Alternatively, the study of a mouse model of human glioma showed several alterations of the macromolecule spectrum, including, but not limited to, increased mobile lipid signals, which had to be taken into account to avoid significant metabolite quantification errors.

Further delineation of the facial 13q14 deletion syndrome in 13 retinoblastoma patients.

Thirteen years ago, Motegi and colleagues (J Med Genet 1987;24:696-697) summarized the specific facial phenotype of six Japanese retinoblastoma patients with interstitial 13q14 deletions. Among a series of 228 propositi with retinoblastoma referred to the Lausanne Retinoblastoma Clinic for treatment and genetic counseling between 1986 and 1997, 13 (5.7%) were diagnosed with a cytogenetic de-novo 13q14 deletion. We confirm the presence of the reported facial phenotype in our population of Caucasian patients and describe additional clinical traits, thus extending the facial phenotype associated with the 13q14 deletion. Del(13q14) comprises, among others, cranial anomalies, frontal bossing, deeply grooved and long philtrum, depressed and broad nasal bridge, bulbous tip of the nose, thick lower lip, thin upper lip, broad cheeks, and large ears and lobules. Recognition of this particular facial appearance was instrumental in the genetic diagnosis of 13q deletions and in the presymptomatic diagnosis of retinoblastoma in a significant number of our cases. Identification of this phenotype in a retinoblastoma patient allows for efficient diagnosis of recurrence in his progeny and/or sibship, while its ignorance will compromise genetic counseling due to the possible difficulties in detecting large deletions by standard molecular mutation analysis. Recognition of this syndrome in newborns without known familial risk for retinoblastoma is even more important as it is a clear warning sign that indicates immediate ophthalmic examination.

Processing of metacaspase into a cytoplasmic catalytic domain mediating cell death in Leishmania major.

Metacaspases are cysteine peptidases that could play a role similar to caspases in the cell death programme of plants, fungi and protozoa. The human protozoan parasite Leishmania major expresses a single metacaspase (LmjMCA) harbouring a central domain with the catalytic dyad histidine and cysteine as found in caspases. In this study, we investigated the processing sites important for the maturation of LmjMCA catalytic domain, the cellular localization of LmjMCA polypeptides, and the functional role of the catalytic domain in the cell death pathway of Leishmania parasites. Although LmjMCA polypeptide precursor form harbours a functional mitochondrial localization signal (MLS), we determined that LmjMCA polypeptides are mainly localized in the cytoplasm. In stress conditions, LmjMCA precursor forms were extensively processed into soluble forms containing the catalytic domain. This domain was sufficient to enhance sensitivity of parasites to hydrogen peroxide by impairing the mitochondrion. These data provide experimental evidences of the importance of LmjMCA processing into an active catalytic domain and of its role in disrupting mitochondria, which could be relevant in the design of new drugs to fight leishmaniasis and likely other protozoan parasitic diseases.

Towards a diffusion image processing validation and accuracy prediction framework

Validation is the main bottleneck preventing theadoption of many medical image processing algorithms inthe clinical practice. In the classical approach,a-posteriori analysis is performed based on someobjective metrics. In this work, a different approachbased on Petri Nets (PN) is proposed. The basic ideaconsists in predicting the accuracy that will result froma given processing based on the characterization of thesources of inaccuracy of the system. Here we propose aproof of concept in the scenario of a diffusion imaginganalysis pipeline. A PN is built after the detection ofthe possible sources of inaccuracy. By integrating thefirst qualitative insights based on the PN withquantitative measures, it is possible to optimize the PNitself, to predict the inaccuracy of the system in adifferent setting. Results show that the proposed modelprovides a good prediction performance and suggests theoptimal processing approach.

Molecular characterization of the processing of arenavirus envelope glycoprotein precursors by subtilisin kexin isozyme-1/site-1 protease.

A crucial step in the life cycle of arenaviruses is the biosynthesis of the mature fusion-active viral envelope glycoprotein (GP) that is essential for virus-host cell attachment and entry. The maturation of the arenavirus GP precursor (GPC) critically depends on proteolytic processing by the cellular proprotein convertase (PC) subtilisin kexin isozyme-1 (SKI-1)/site-1 protease (S1P). Here we undertook a molecular characterization of the SKI-1/S1P processing of the GPCs of the prototypic arenavirus lymphocytic choriomeningitis virus (LCMV) and the pathogenic Lassa virus (LASV). Previous studies showed that the GPC of LASV undergoes processing in the endoplasmic reticulum (ER)/cis-Golgi compartment, whereas the LCMV GPC is cleaved in a late Golgi compartment. Herein we confirm these findings and provide evidence that the SKI-1/S1P recognition site RRLL, present in the SKI-1/S1P prodomain and LASV GPC, but not in the LCMV GPC, is crucial for the processing of the LASV GPC in the ER/cis-Golgi compartment. Our structure-function analysis revealed that the cleavage of arenavirus GPCs, but not cellular substrates, critically depends on the autoprocessing of SKI-1/S1P, suggesting differences in the processing of cellular and viral substrates. Deletion mutagenesis showed that the transmembrane and intracellular domains of SKI-1/S1P are dispensable for arenavirus GPC processing. The expression of a soluble form of the protease in SKI-I/S1P-deficient cells resulted in the efficient processing of arenavirus GPCs and rescued productive virus infection. However, exogenous soluble SKI-1/S1P was unable to process LCMV and LASV GPCs displayed at the surface of SKI-I/S1P-deficient cells, indicating that GPC processing occurs in an intracellular compartment. In sum, our study reveals important differences in the SKI-1/S1P processing of viral and cellular substrates.

Decision-theoretic reflections on processing a fingermark

A recent publication in this journal [Neumann et al., Forensic Sci. Int. 212 (2011) 32-46] presented the results of a field study that revealed the data provided by the fingermarks not processed in a forensic science laboratory. In their study, the authors were interested in the usefulness of this additional data in order to determine whether such fingermarks would have been worth submitting to the fingermark processing workflow. Taking these ideas as a starting point, this communication here places the fingermark in its context of a case brought before a court, and examines the question of processing or not processing a fingermark from a decision-theoretic point of view. The decision-theoretic framework presented provides an answer to this question in the form of a quantified expression of the expected value of information (EVOI) associated with the processed fingermark, which can then be compared with the cost of processing the mark.

Atmung, Aufmerksamkeit und Ablenkung als Funktion emotionaler Stimuli: Ablenkung, Atmung, Aufmerksamkeit, Emotion, Erregung, Valenz

Mittels Bilder, Musikstücken und Geräuschen induzierten wir Emotionen und gingen einerseits der Frage nach, wie emotionale Bewertung und physiologische Vorgänge, insbesondere die Atmung, miteinander verknüpft sind. Andererseits untersuchten wir mit Geruchsexpositionen während einer Mehrfachverrichtung, welche Rolle die Geruchs-Valenz bei der Arbeitsablenkung spielt. Unsere Versuche zeigten, dass die Atmungsantworten auf induzierte Emotionen in einem gewissen Rahmen dem Dimensionsmodell von Valenz und Arousal folgten, insbesondere bildeten sie die induzierte Erregung konsistent ab. Auch das Aufmerksamkeits-Engagement hing von der emotionalen Bedeutung des Stimulus ab, da nur die negativ attribuierten Gerüche eine Leistungsminderung in der Mehrfachverrichtung auslösten. [Autoren]

Deontological and altruistic guilt: evidence for distinct neurobiological substrates.

The feeling of guilt is a complex mental state underlying several human behaviors in both private and social life. From a psychological and evolutionary viewpoint, guilt is an emotional and cognitive function, characterized by prosocial sentiments, entailing specific moral believes, which can be predominantly driven by inner values (deontological guilt) or by more interpersonal situations (altruistic guilt). The aim of this study was to investigate whether there is a distinct neurobiological substrate for these two expressions of guilt in healthy individuals. We first run two behavioral studies, recruiting a sample of 72 healthy volunteers, to validate a set of stimuli selectively evoking deontological and altruistic guilt, or basic control emotions (i.e., anger and sadness). Similar stimuli were reproduced in a event-related functional magnetic resonance imaging (fMRI) paradigm, to investigate the neural correlates of the same emotions, in a new sample of 22 healthy volunteers. We show that guilty emotions, compared to anger and sadness, activate specific brain areas (i.e., cingulate gyrus and medial frontal cortex) and that different neuronal networks are involved in each specific kind of guilt, with the insula selectively responding to deontological guilt stimuli. This study provides evidence for the existence of distinct neural circuits involved in different guilty feelings. This complex emotion might account for normal individual attitudes and deviant social behaviors. Moreover, an abnormal processing of specific guilt feelings might account for some psychopathological manifestation, such as obsessive-compulsive disorder and depression.

Risk perception, emotion regulation and impulsivity as predictors of risk behaviours among adolescents in Switzerland

The purpose of this study was to explore the frequency of risk behaviours among Swiss adolescents and their links with risk perception, impulsivity and emotion regulation abilities, operationalized with the concepts of alexithymia and emo- tional openness. We recruited 144 subjects (aged 14-20), who completed the Risk Involvement and Perception Scale (RIPS-R), the UPPS Impulsive Behavior Scale, the 20-item Toronto Alexithymia Scale (TAS-20), and the 20-item Dimensions of Openness to Emotional Experiences (DOE-20) questionnaire. Findings revealed that a greater perception of benefits and a higher level of sensation seeking were associated with more involvement in risk behaviours, which are essentially socially accepted behaviours. Notably, the path model indicated that the perception of benefits was a mediator in the relationship between sensation seeking and risk behaviours. The results add to the psychological understanding of factors associated with risk behaviours in adolescence. The limitations and implications of these results for developmental theories, research, and prevention are stated.

Neurocognitive deficits and personality traits among euthymic patients with mood disorders in late life.

BACKGROUND: Previous studies revealed that acute depressive episodes are associated with both cognitive deficits and modified personality patterns in late life. Whether or not these psychological changes are present after remission remains a matter of debate. To date, no study provided concomitant assessment of cognition and psychological functions in this particular clinical setting. METHOD: Using a cross-sectional design, 58 remitted outpatients (36 with unipolar early-onset depression (EOD) and 22 with bipolar disorder (BD)) were compared to 62 healthy controls. Assessment included detailed neurocognitive measures and evaluation of the five factor personality dimensions (NEO-Personality Inventory). RESULTS: Group comparisons revealed significant slower processing speed, working and episodic memory performances in BD patients. EOD patients showed cognitive abilities comparable to those of elderly controls. In NEO PI assessment, both BD and EOD patients displayed higher Depressiveness facet scores. In addition, the EOD but not BD group had lower Extraversion factor, and Warmth and Positive Emotion facet scores than controls. CONCLUSIONS: After remission from acute affective symptoms, older BD patients show significant impairment in several cognitive functions while neuropsychological performances remained intact in elderly patients with EOD. Supporting a long-lasting psychological vulnerability, EOD patients are more prone to develop emotion-related personality trait changes than BD patients.