106 research outputs found
Correlations of r-Process Elements in Very Metal-Poor Stars as Clues to their Nucleosynthesis Sites
Various nucleosynthesis studies have pointed out that the r-process elements
in very metal-poor (VMP) halo stars might have different origins. By means of
familiar concepts from statistics (correlations, cluster analysis, rank tests
of elemental abundances), we look for causally correlated elemental abundance
patterns and attempt to link them to astrophysical events. Some of these events
produce the r-process elements jointly with iron, while others do not have any
significant iron contribution. In the early stage of our Galaxy, at least three
r-process nucleosynthesis sites have been active. The first two produce and
eject iron and the majority of the lighter r-process elements. We assign them
to two different types of core-collapse events, not identical to regular
core-collapse supernovae (CCSNe), which produce only light trans-Fe elements.
The third category is characterized by a strong r-process and responsible for
the major fraction of the heavy main r-process elements without a significant
co-production of Fe. It does not appear to be connected to CCSNe, in fact the
Fe found in the related r-process enriched stars must come from previously
occurring CCSNe. The existence of actinide boost stars indicates a further
division among strong r-process sites. We assign these two strong r-process
sites to neutron star mergers without fast black hole formation and to events
where the ejecta are dominated by black hole accretion disk outflows.
Indications from the lowest-metallicity stars hint at a connection to massive
single stars (collapsars) forming black holes in the early Galaxy.Comment: 40 pages, 25 figures, 10 table
Современные методы визуализации реалистичных трехмерных ландшафтов в тренажерных системах имитации движения
У статті описані основні сучасні методи візуалізації реалістичних тривимірних ландшафтів у тренажерних системах імітації руху, їхні достоїнства й недоліки. Показано напрямок подальших досліджень для вдосконалення існуючих методів.In papers the basic modern methods of visualisation of realistic three-dimensional landscapesin training systems of imitation of movement, their merits and demerits are reviewed. The direction of the further researches for improvement of existing methods is shown
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The impact of dairy products in the development of type 2 diabetes: where does the evidence stand in 2019?
The prevalence of type 2 diabetes (T2D) has increased rapidly. Adopting a heathy diet is suggested as one of the effective behaviors to prevent or delay onset of T2D. Dairy consumption has been recommended as part of a healthy diet, but there remains uncertainty in both the scientific community and the public about the effect of different dairy products on T2D risk. In a recent workshop, the evidence on dairy products and T2D risk was presented and discussed by a group of experts. The main conclusions from the workshop are presented in this position paper and are as follows. 1) Available evidence from large prospective cohort studies and limited randomized controlled trials (RCTs) suggests that total dairy consumption has a neutral or moderately beneficial effect on T2D risk. 2) Increasing evidence from prospective cohort studies indicates that yogurt is most strongly associated with a lower T2D risk, but evidence from RCTs is scarce. 3) Fatty acids from dairy (medium-chain, odd, and very long-chain SFAs as well as trans-palmitoleic acid) are associated with lower T2D risk and improved metabolic health, but more research is needed on studies that explore cause and effect relations to exclude the possibility that the dairy fatty acids simply serve as markers of overall dairy consumption. 4) The food matrix can be a stronger determinant of health effects than SFA content. This review further identifies research gaps in the existing knowledge and highlights key research questions that need to be addressed to better understand the impact of dairy consumption on future T2D risk
Prenatally traumatized mice reveal hippocampal methylation and expression changes of the stress-related genes Crhr1 and Fkbp5
In our previous study, we found that prenatal trauma exposure leads to an anxiety phenotype in mouse pups, characterized by increased corticosterone levels and increased anxiety-like behavior. In order to understand the mechanisms by which aversive in utero experience leads to these long-lasting behavioral and neuroendocrine changes, we investigated stress reactivity of prenatally traumatized (PT) mice, as well as the expression and methylation levels of several key regulatory genes of the stress axis in the dorsal hippocampus (dHPC) of the PT embryo and adult mice. We detected increased corticotropin-releasing hormone receptor 1 (Crhr1) and decreased FK506 binding protein 5 (Fkbp5) mRNA levels in the left dHPC of adult PT mice. These alterations were accompanied by a decreased methylation status of the Crhr1 promoter and an increased methylation status of the Fkbp5 promoter, respectively. Interestingly, the changes in Fkbp5 and Crhr1 mRNA levels were not detected in the embryonic dHPC of PT mice. Together, our findings provide evidence that prenatal trauma has a long-term impact on stress axis function and anxiety phenotype associated with altered Crhr1 and Fkbp5 transcripts and promoter methylation
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DNA methylation-based classification of central nervous system tumours.
Accurate pathological diagnosis is crucial for optimal management of patients with cancer. For the approximately 100 known tumour types of the central nervous system, standardization of the diagnostic process has been shown to be particularly challenging-with substantial inter-observer variability in the histopathological diagnosis of many tumour types. Here we present a comprehensive approach for the DNA methylation-based classification of central nervous system tumours across all entities and age groups, and demonstrate its application in a routine diagnostic setting. We show that the availability of this method may have a substantial impact on diagnostic precision compared to standard methods, resulting in a change of diagnosis in up to 12% of prospective cases. For broader accessibility, we have designed a free online classifier tool, the use of which does not require any additional onsite data processing. Our results provide a blueprint for the generation of machine-learning-based tumour classifiers across other cancer entities, with the potential to fundamentally transform tumour pathology
High-sensitivity microsatellite instability assessment for the detection of mismatch repair defects in normal tissue of biallelic germline mismatch repair mutation carriers
Introduction: Lynch syndrome (LS) and constitutional mismatch repair deficiency (CMMRD) are hereditary cancer syndromes associated with mismatch repair (MMR) deficiency. Tumours show microsatellite instability (MSI), also reported at low levels in non-neoplastic tissues. Our aim was to evaluate the performance of high-sensitivity MSI (hs-MSI) assessment for the identification of LS and CMMRD in non-neoplastic tissues. Materials and methods: Blood DNA samples from 131 individuals were grouped into three cohorts: baseline (22 controls), training (11 CMMRD, 48 LS and 15 controls) and validation (18 CMMRD and 18 controls). Custom next generation sequencing panel and bioinformatics pipeline were used to detect insertions and deletions in microsatellite markers. An hs-MSI score was calculated representing the percentage of unstable markers. Results: The hs-MSI score was significantly higher in CMMRD blood samples when compared with controls in the training cohort (p<0.001). This finding was confirmed in the validation set, reaching 100% specificity and sensitivity. Higher hs-MSI scores were detected in biallelic MSH2 carriers (n=5) compared with MSH6 carriers (n=15). The hs-MSI analysis did not detect a difference between LS and control blood samples (p=0.564). Conclusions: The hs-MSI approach is a valuable tool for CMMRD diagnosis, especially in suspected patients harbouring MMR variants of unknown significance or non-detected biallelic germline mutations. Keywords: constitutional mismatch repair deficiency; highly sensitive methodologies; lynch syndrome; microsatellite instability; next generation sequencing
Influence of Stimulant Medication and Response Speed on Lateralization of Movement-Related Potentials in Attention-Deficit/Hyperactivity Disorder
Hyperactivity is one of the core symptoms in attention deficit hyperactivity disorder (ADHD). However, it remains unclear in which way the motor system itself and its development are affected by the disorder. Movement-related potentials (MRP) can separate different stages of movement execution, from the programming of a movement to motor post-processing and memory traces. Pre-movement MRP are absent or positive during early childhood and display a developmental increase of negativity. We examined the influences of response-speed, an indicator of the level of attention, and stimulant medication on lateralized MRP in 16 children with combined type ADHD compared to 20 matched healthy controls. We detected a significantly diminished lateralisation of MRP over the pre-motor and primary motor cortex during movement execution (initial motor potential peak, iMP) in patients with ADHD. Fast reactions (indicating increased visuo-motor attention) led to increased lateralized negativity during movement execution only in healthy controls, while in children with ADHD faster reaction times were associated with more positive amplitudes. Even though stimulant medication had some effect on attenuating group differences in lateralized MRP, this effect was insufficient to normalize lateralized iMP amplitudes.A reduced focal (lateralized) motor cortex activation during the command to muscle contraction points towards an immature motor system and a maturation delay of the (pre-) motor cortex in children with ADHD. A delayed maturation of the neuronal circuitry, which involves primary motor cortex, may contribute to ADHD pathophysiology
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