302 research outputs found
Dynamic phase transition of the Blume-Capel model in an oscillating magnetic field
We employ numerical simulations and finite-size scaling techniques to
investigate the properties of the dynamic phase transition that is encountered
in the Blume-Capel model subjected to a periodically oscillating magnetic
field. We mainly focus on the study of the two-dimensional system for various
values of the crystal-field coupling in the second-order transition regime. Our
results indicate that the present non-equilibrium phase transition belongs to
the universality class of the equilibrium Ising model and allow us to construct
a dynamic phase diagram, in analogy to the equilibrium case, at least for the
range of parameters considered. Finally, we present some complementary results
for the three-dimensional model, where again the obtained estimates for the
critical exponents fall into the universality class of the corresponding
three-dimensional equilibrium Ising ferromagnet.Comment: 27 pages, 1 table, 15 figures, minor corrections (updated figures 3
and 4
The triticeous cartilage — redefining of morphology, prevalence and function
Background: Triticeous cartilage is a small cartilaginous component of the laryngeal skeleton. This cartilage, located in posterior end of the thyrohyoid ligament, presents in different shapes. Radiological studies indicate clinical and anatomical importance of the triticeous cartilage but these studies have limited information due to inadequate inspection method. Computed tomographic angiography is able to evaluate the triticeous cartilage with using three-dimensional images in more detail. The aim of this study is to describe prevalence and morphological properties of the triticeous cartilage.
Materials and methods: We examined computed tomographic angiography images of 746 patients (368 women, 378 men) retrospectively. Shapes, calcification degrees, volumes, lengths and wideness of the triticeous cartilage were evaluated by OsiriX-Lite software.
Results: According to our results, triticeous cartilage presents common in the examined population (68.1%). The prevalence of the triticeous cartilage was higher in men than in women. We also found that the degree of calcification was not related with age and gender.
Conclusions: Clinical importance of the triticeous cartilage is that it could be misdiagnosed with atherosclerosis in common carotid artery because the triticeous cartilage is located almost at same level as the bifurcation of the common carotid artery. Therefore, clinicians should be aware about the triticeous cartilage
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Default Mode Contributions to Automated Information Processing
Concurrent with mental processes that require rigorous computation and control, a series of automated decisions and actions govern our daily lives, providing efficient and adaptive responses to environmental demands. Using a cognitive flexibility task, we show that a set of brain regions collectively known as the default mode network play a crucial role in such “autopilot” behavior, i.e. when rapidly selecting appropriate responses under predictable behavioral contexts. While applying learned rules, the default mode network shows both greater activity and connectivity. Furthermore, functional interactions between this network and hippocampal, parahippocampal areas as well as primary visual cortex correlate with the speed of accurate responses. These findings indicate a memory-based “autopilot role” for the default mode network, which may have important implications for our current understanding of healthy and adaptive brain processing.We thank Mrs. Victoria Lupson, Ms. Karen Welsh, Dr. Marius Mada, and the rest of the staff in the Wolfson Brain Imaging Centre (WBIC) at Addenbrooke’s Hospital for their assistance in MRI scanning. In addition, we thank all the participants for their contribution to this study. This study was funded by the Yousef Jameel Academic Program grant (awarded to D.V.). Additionally, D.K.M. is supported by the National Institute for Health Research (NIHR) Cambridge Biomedical Centre (RCZB/004) and an NIHR Senior Investigator Award (RCZB/014), and E.A.S. is funded by the Stephen Erskine Fellowship Queens’ College, Cambridge
A comparative study of mental health of medical students in two countries
Results from many studies indicate that throughout medical education students experience high levels of stress and depression. The aim of the current study was to assess and compare Bulgarian and Turkish medical students' levels of stress and depression. A cross-sectional study was conducted with 546 students (276 foreign students from Medical University – Sofia and 270 medical students from several medical universities in Ankara). The study instrument included basic socio-demographic questions, Medical Student Stressor Questionnaire (MSSQ-40 items) and Beck Depression Inventory (BDI). Turkish medical students showed higher levels of stress and depression than foreign students from Bulgaria. We found that all types of stressors in medical students had a relationship with depression. Results of our study imply that medical students need access to psychological support throughout their education
Relationship of the bovine IGF1, TG, DGAT1 and MYF5 genes to meat colour, tenderness and cooking loss
ΔΕΝ ΔΙΑΤΙΘΕΤΑΙ ΠΕΡΙΛΗΨΗBovine insulin-like growth factor 1 (IGF1), thyroglobulin (TG), diacylglycerol-O-acyltransferase 1 (DGAT1) and myogenic factor 5 (MYF5) genes play an important role in the physiology of lipid and muscle metabolism and are therefore considered as candidate genes for meat production traits in farm animals. The objectives of this study were to investigate single nucleotide polymorphisms (SNPs) in IGF1, TG, DGAT1 and MYF5 genes and to evaluate whether these polymorphisms affected meat colour, tenderness and cooking loss in Holstein cattle. Initially, the SNPs were detected by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) method. Meat samples (N= 50) derived from M. longissimus thoracis et lumborum (LTL) were used in the current study. Significant differences in variations of meat colour parameters were observed at 24 hours post-mortem. IGF1 was associated with colour parameters of a* and chroma values. In addition, effects of TG were statistically significant on L* and a* values, while, effects of MYF5 were significant on a* value. There was no association of the tested SNPs with meat pH, tenderness and cooking loss. The results presented here may give the valuable information for improving meat colour in cattle
Distinct patterns of thought mediate the link between brain functional connectomes and well-being
Ongoing thought patterns constitute important aspects of both healthy and abnormal human cognition. However, the neural mechanisms behind these daily experiences and their contribution to well-being remain a matter of debate. Here, using resting-state fMRI and retrospective thought sampling in a large neurotypical cohort (n = 211), we identified two distinct patterns of thought, broadly describing the participants’ current concerns and future plans, that significantly explained variability in the individual functional connectomes. Consistent with the view that ongoing thoughts are an emergent property of multiple neural systems, network-based analysis highlighted the central importance of both unimodal and transmodal cortices in the generation of these experiences. Importantly, while state-dependent current concerns predicted better psychological health, mediating the effect of functional connectomes, trait-level future plans were related to better social health, yet with no mediatory influence. Collectively, we show that ongoing thoughts can influence the link between brain physiology and well-being
Anterior Thalamic High Frequency Band Activity Is Coupled with Theta Oscillations at Rest
Cross-frequency coupling (CFC) between slow and fast brain rhythms, in the form of phase–amplitude coupling (PAC), is proposed to enable the coordination of neural oscillatory activity required for cognitive processing. PAC has been identified in the neocortex and mesial temporal regions, varying according to the cognitive task being performed and also at rest. PAC has also been observed in the anterior thalamic nucleus (ATN) during memory processing. The thalamus is active during the resting state and has been proposed to be involved in switching between task-free cognitive states such as rest, in which attention is internally-focused, and externally-focused cognitive states, in which an individual engages with environmental stimuli. It is unknown whether PAC is an ongoing phenomenon during the resting state in the ATN, which is modulated during different cognitive states, or whether it only arises during the performance of specific tasks. We analyzed electrophysiological recordings of ATN activity during rest from seven patients who received thalamic electrodes implanted for treatment of pharmacoresistant focal epilepsy. PAC was identified between theta (4–6 Hz) phase and high frequency band (80–150 Hz) amplitude during rest in all seven patients, which diminished during engagement in tasks involving an external focus of attention. The findings are consistent with the proposal that theta–gamma coupling in the ATN is an ongoing phenomenon, which is modulated by task performance
Transcranial Low-Level Laser Therapy Improves Neurological Performance in Traumatic Brain Injury in Mice: Effect of Treatment Repetition Regimen
Low-level laser (light) therapy (LLLT) has been clinically applied around the world for a spectrum of disorders requiring healing, regeneration and prevention of tissue death. One area that is attracting growing interest in this scope is the use of transcranial LLLT to treat stroke and traumatic brain injury (TBI). We developed a mouse model of severe TBI induced by controlled cortical impact and explored the effect of different treatment schedules. Adult male BALB/c mice were divided into 3 broad groups (a) sham-TBI sham-treatment, (b) real-TBI sham-treatment, and (c) real-TBI active-treatment. Mice received active-treatment (transcranial LLLT by continuous wave 810 nm laser, 25 mW/cm[superscript 2], 18 J/cm[superscript 2], spot diameter 1 cm) while sham-treatment was immobilization only, delivered either as a single treatment at 4 hours post TBI, as 3 daily treatments commencing at 4 hours post TBI or as 14 daily treatments. Mice were sacrificed at 0, 4, 7, 14 and 28 days post-TBI for histology or histomorphometry, and injected with bromodeoxyuridine (BrdU) at days 21–27 to allow identification of proliferating cells. Mice with severe TBI treated with 1-laser Tx (and to a greater extent 3-laser Tx) had significant improvements in neurological severity score (NSS), and wire-grip and motion test (WGMT). However 14-laser Tx provided no benefit over TBI-sham control. Mice receiving 1- and 3-laser Tx had smaller lesion size at 28-days (although the size increased over 4 weeks in all TBI-groups) and less Fluoro-Jade staining for degenerating neurons (at 14 days) than in TBI control and 14-laser Tx groups. There were more BrdU-positive cells in the lesion in 1- and 3-laser groups suggesting LLLT may increase neurogenesis. Transcranial NIR laser may provide benefit in cases of acute TBI provided the optimum treatment regimen is employed.National Institutes of Health (U.S.) (Grant R01AI050875)Center for Integration of Medicine and Innovative Technology (DAMD17-02-2-0006)United States. Dept. of Defense. Congressionally Directed Medical Research Programs (W81XWH-09-1-0514)United States. Air Force Office of Scientific Research. Military Photomedicine Program (FA9550-11-1-0331
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Angular Default Mode Network Connectivity across Working Memory Load
Initially identified during no-task, baseline conditions, it has now been suggested that the default mode network (DMN) engages during a variety of working memory paradigms through its flexible interactions with other large-scale brain networks. Nevertheless, its contribution to whole-brain connectivity dynamics across increasing working memory load has not been explicitly assessed. The aim of our study was to determine which DMN hubs relate to working memory task performance during an fMRI-based -back paradigm with parametric increases in difficulty. Using a voxel-wise metric, termed the intrinsic connectivity contrast (ICC), we found that the bilateral angular gyri (core DMN hubs) displayed the greatest change in global connectivity across three levels of -back task load. Subsequent seed-based functional connectivity analysis revealed that the angular DMN regions robustly interact with other large-scale brain networks, suggesting a potential involvement in the global integration of information. Further support for this hypothesis comes from the significant correlations we found between angular gyri connectivity and reaction times to correct responses. The implication from our study is that the DMN is actively involved during the n-back task and thus plays an important role related to working memory, with its core angular regions contributing to the changes in global brain connectivity in response to increasing environmental demands.Evelyn Trust (RUAG/018), Yousef Jameel Academic Program, National Institute for Health Research Cambridge Biomedical Centre (RCZB/004), National Institute for Health Research (Senior Investigator Award (RCZB/014)), Queens’ College Cambridge (Stephen Erskine Fellowship
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