26 research outputs found

    Analysis of the phenomenon of speculative trading in one of its basic manifestations: postage stamp bubbles

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    We document and analyze the empirical facts concerning one of the clearest evidence of speculation in financial trading as observed in the postage collection stamp market. We unravel some of the mechanisms of speculative behavior which emphasize the role of fancy and collective behavior. In our conclusion, we propose a classification of speculative markets based on two parameters, namely the amplitude of the price peak and a second parameter that measures its ``sharpness''. This study is offered to anchor modeling efforts to realistic market constraints and observations.Comment: 9 pages, 5 figures and 2 tables, in press in Int. J. Mod. Phys.

    Low signal intensity in motor cortex on susceptibility-weighted MR imaging is correlated with clinical signs of amyotrophic lateral sclerosis: a pilot study

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    There is no reliable objective indicator for upper motor neuron dysfunction in amyotrophic lateral sclerosis (ALS). Todetermine the clinical significance and potential utility of magnetic resonance (MR) signals, we investigated the relationshipbetween clinical symptoms and susceptibility changes in the motor cortex measured using susceptibility-weighted MRimaging taken by readily available 3-T MRI in clinical practice. Twenty-four ALS patients and 14 control subjects underwent3-T MR T1-weighted imaging and susceptibility-weighted MR imaging with the principles of echo-shifting with a train ofobservations (PRESTO) sequence. We analysed relationships between relative susceptibility changes in the motor cortexassessed using voxel-based analysis (VBA) and clinical scores, including upper motor neuron score, ALS functional ratingscale revised score, and Medical Research Council sum score on physical examination. Patients with ALS exhibited significantlylower signal intensity in the precentral gyrus on susceptibility-weighted MR imaging compared with controls. Clinicalscores were significantly correlated with susceptibility changes. Importantly, the extent of the susceptibility changes in thebilateral precentral gyri was significantly correlated with upper motor neuron scores. The results of our pilot study usingVBA indicated that low signal intensity in motor cortex on susceptibility-weighted MR imaging may correspond to clinicalsymptoms, particularly upper motor neuron dysfunction. Susceptibility-weighted MR imaging may be a useful diagnostictool as an objective indicator of upper motor neuron dysfunction

    Action-rule-based cognitive control enables efficient execution of stimulus–response conflict tasks: a model validation of Simon task performance

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    Introduction: The human brain can flexibly modify behavioral rules to optimize task performance (speed and accuracy) by minimizing cognitive load. To show this flexibility, we propose an action-rule-based cognitive control (ARC) model. The ARC model was based on a stochastic framework consistent with an active inference of the free energy principle, combined with schematic brain network systems regulated by the dorsal anterior cingulate cortex (dACC), to develop several hypotheses for demonstrating the validity of the ARC model. Methods: A step-motion Simon task was developed involving congruence or incongruence between important symbolic information (illustration of a foot labeled “L” or “R,” where “L” requests left and “R” requests right foot movement) and irrelevant spatial information (whether the illustration is actually of a left or right foot). We made predictions for behavioral and brain responses to testify to the theoretical predictions. Results: Task responses combined with event-related deep-brain activity (ER-DBA) measures demonstrated a key contribution of the dACC in this process and provided evidence for the main prediction that the dACC could reduce the Shannon surprise term in the free energy formula by internally reversing the irrelevant rapid anticipatory postural adaptation. We also found sequential effects with modulated dip depths of ER-DBA waveforms that support the prediction that repeated stimuli with the same congruency can promote remodeling of the internal model through the information gain term while counterbalancing the surprise term. Discussion: Overall, our results were consistent with experimental predictions, which may support the validity of the ARC model. The sequential effect accompanied by dip modulation of ER-DBA waveforms suggests that cognitive cost is saved while maintaining cognitive performance in accordance with the framework of the ARC based on 1-bit congruency-dependent selective control

    Efficacy of a non-pharmaceutical multimodal intervention program in a group setting for patients with mild cognitive impairment: A single-arm interventional study with pre-post and external control analyses

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    Aim: This study aimed to evaluate the efficacy of a non-pharmaceutical multimodal intervention program consisting of physical exercise, cognitive stimulation, and health education in a group setting to slow the progression of mild cognitive impairment (MCI). Methods: A single-arm interventional study was conducted on 27 patients with MCI. To evaluate the efficacy of the intervention program, a pre-post analysis was performed using EuroQol-5 Dimension (EQ-5D), Mini-Mental State Examination (MMSE), Cognitive Function Instrument (CFI), 5 Cog test, depression, and physical performance before and after the 8-month intervention. Additionally, propensity score and the semi-Bayes analyses were performed to compare the intervention program with standard medical care, using the external control patients’ data for MMSE scores. Results: Twenty-four patients completed the intervention program. During the study period, although EQ-5D and MMSE scores remained unchanged (mean change 0.02 [95 % confidence interval (CI): −0.004, 0.04], 0.5 [-0.2, 1.3]), CFI and the subcategories of 5Cog (attention and reasoning) improved (mean change −1.23 [-2.24, −0.21], 4.3 [0.9, 7.7], 3.0 [0.4, 5.6]). In the additional analysis comparing changes in MMSE scores, patients who underwent the intervention program had less decline than the external control patients (mean change −1.7 [-2.1, −1.3]) with an observed mean difference of 2.25 [1.46, 3.03], and propensity score-adjusted difference of 2.26 [1.46, 3.05]. The semi-Bayesian approach also suggested that the intervention slowed the progression of MCI. Conclusion: A non-pharmaceutical multimodal intervention program could contribute to slowing cognitive decline in patients with MCI

    Survey on the current situation for early diagnosis of dementia and contributing factors in Japan

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    Background: Early diagnosis of dementia is important for both initiation of non-pharmacological activities to slow cognitive decline as well as the development of disease-modifying drugs; however, it appears there may be a tendency for formal diagnosis to be delayed. Since the current status of diagnosis in Japan is unclear, we conducted a survey with family caregivers of patients with dementia using questionnaires and interviews to investigate the factors regarding the dementia diagnosis process in Japan. Methods: We distributed questionnaires to family caregivers of people with dementia and conducted additional follow-up interviews with approximately half of them. We calculated odds ratios for the time to diagnosis using logistic regression analysis for each characteristic from the questionnaire data. We also created co-occurrence networks from the interview data in order to provide qualitative context to the questionnaire data. Results: We collected 68 questionnaires and conducted 32 interviews. The median time to diagnosis was 12 months, and logistic regression analysis showed a significant trend toward shorter time to diagnosis in the absence of other caregivers. In addition, there were significant differences in age, relationship with patients and the time from the first visit to the final diagnosis between groups with and without other caregivers. Conclusions: The results of this study suggest that the presence or absence of other caregivers may affect caregivers' behaviour and the time taken to receive a diagnosis of dementia. These findings indicate it may be beneficial to predict inhibiting factors and change approaches based on caregivers' and patients' background to promote early diagnosis

    Kobe project for the exploration of newer strategies to reduce the social burden of dementia: a study protocol of cohort and intervention studies

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    Introduction This research project addresses the lack of screening tools for the early detection of high-risk individuals for long-term care, through four individual studies.Study 1 investigates the predictive ability of the ‘Kihon Check List’, study 2 the ‘Cognitive Function instrument’ and EuroQol-5 Dimension (EQ-5D) and study 3 the ‘Cognitive Function instrument’ and EQ-5D as well as the ‘Frail Kenshin’ health check-up, for incident long-term care certification over a follow-up period of up to 4 years. This is the first large prospective study to evaluate the predictive ability of these tools for the outcome measure long-term care certification. The last subsection of this project study four aims to explore a mixed methods intervention for delaying the need for long-term care. This section is purely exploratory, looking for clues for further studies.Methods and analysis Baseline data have been collected through local government programs, as well as through postal self-reported questionnaires. The primary outcome variable for all studies is long-term care certification data. Statistical analysis will be carried out using Kaplan-Meier, Multiple Cox regression as well as logistic regression.Conclusion This project hopes to identify tools effective in predicting long-term care need. This will enable identification of citizens that are of higher risk for long-term care in the near future. This subset of high-risk individuals can in the future be addressed for extra support/intervention.Ethics and dissemination All studies have been approved by respective institutional ethical committees and the WHO ethical committee ERC.0002899. In addition, all studies conform to the provisions of the Declaration of Helsinki and are conducted in accordance with Japan’s ‘Ethical Guidelines for Medical and Health Research Involving Human Subjects’. All findings will be disseminated at conferences and published in peer-reviewed journals.Trial registration number UMIN000023283

    Mostly Separate Distributions of CLAC- versus Aβ40- or Thioflavin S-Reactivities in Senile Plaques Reveal Two Distinct Subpopulations of β-Amyloid Deposits

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    Collagenous Alzheimer amyloid plaque component (CLAC) is a unique non-Aβ amyloid component of senile plaques (SP) derived from a transmembrane collagen termed CLAC-precursor. Here we characterize the chronological and spatial relationship of CLAC with other features of SP amyloid in the brains of patients with Alzheimer’s disease (AD), Down syndrome (DS), and of PSAPP transgenic mice. In AD and DS cerebral cortex, CLAC invariably colocalized with Aβ42 but often lacked Aβ40- or thioflavin S (thioS)-reactivities. Immunoelectron microscopy of CLAC-positive SP showed labeling of fibrils that are more loosely dispersed compared to typical amyloid fibrils in CLAC-negative SP. In DS cerebral cortex, diffuse plaques in young patients were negative for CLAC, whereas a subset of SP became CLAC-positive in patients aged 35 to 50 years, before the appearance of Aβ40. In DS cases over 50 years of age, Aβ40-positive SP dramatically increased, whereas CLAC burden remained at a constant level. In PSAPP transgenic mice, CLAC was positive in the diffuse Aβ deposits surrounding huge-cored plaques. Thus, CLAC and Aβ40 or thioS exhibit mostly separate distribution patterns in SP, suggesting that CLAC is a relatively early component of SP in human brains that may have inhibitory effects against the maturation of SP into β-sheet-rich amyloid deposits
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