Cardiovascular Diseases Diagnosis Using an ECG Multi-Band Non-Linear Machine Learning Framework Analysis

BACKGROUND

cardiovascular diseases (CVDs), which encompass heart and blood vessel issues, stand as the leading cause of global mortality for many people.

METHODS

the present study intends to perform discrimination between seven well-known CVDs (bundle branch block, cardiomyopathy, myocarditis, myocardial hypertrophy, myocardial infarction, valvular heart disease, and dysrhythmia) and one healthy control group, respectively, by feeding a set of machine learning (ML) models with 10 non-linear features extracted every 1 s from electrocardiography (ECG) lead signals of a well-known ECG database (PTB diagnostic ECG database) using multi-band analysis performed by discrete wavelet transform (DWT). The ML models were trained and tested using a leave-one-out cross-validation approach, assessing the individual and combined capabilities of features, per each lead or combined, to distinguish between pairs of study groups and for conducting a comprehensive all vs. all analysis.

RESULTS

the Accuracy discrimination results ranged between 73% and 100%, the Recall between 68% and 100%, and the AUC between 0.42 and 1.

CONCLUSIONS

the results suggest that our method is a good tool for distinguishing CVDs, offering significant advantages over other studies that used the same dataset, including a multi-class comparison group (all vs. all), a wider range of binary comparisons, and the use of classical non-linear analysis under ECG multi-band analysis performed by DWT.

Critical Phase Dualities in 1D Exactly Solvable Quasiperiodic Models

We propose a solvable class of 1D quasiperiodic tight-binding models encompassing extended, localized, and critical phases, separated by nontrivial mobility edges. Limiting cases include the Aubry-André model and the models of Sriram Ganeshan, J. H. Pixley, and S. Das Sarma [Phys. Rev. Lett. 114, 146601 (2015)PRLTAO0031-900710.1103/PhysRevLett.114.146601] and J. Biddle and S. Das Sarma [Phys. Rev. Lett. 104, 070601 (2010)PRLTAO0031-900710.1103/PhysRevLett.104.070601]. The analytical treatment follows from recognizing these models as a novel type of fixed points of the renormalization group procedure recently proposed in Phys. Rev. B 108, L100201 (2023)10.1103/PhysRevB.108.L100201 for characterizing phases of quasiperiodic structures. Beyond known limits, the proposed class of models extends previously encountered localized-delocalized duality transformations to points within multifractal critical phases. Besides an experimental confirmation of multifractal duality, realizing the proposed class of models in optical lattices allows stabilizing multifractal critical phases and nontrivial mobility edges in an undriven system without the need for the unbounded potentials required by previous proposals.

Pre-task Intrinsic Cortical Activity in Novice and Experienced Military Specialists: A Cross-sectional Study

INTRODUCTION

Neuroscience studies brain dynamics through the analysis of electrical signals. Cortical activity estimated by electroencephalography brings accurate information about perceptions of human behavior. The examination of resting states in relation to subsequent behaviors indicates that intrinsic cortical activity (ICA) has implications for decision-making processes, especially when inserted in the context of military activities and associated with stress. The objective of this study was to compare the absolute alpha power (AAP) in the ICA in the pre-task moment of novice specialized military (NG) with experienced (ExpG), associating with the level of stress.

MATERIALS AND METHODS

This was a cross-sectional, observational study with 19 military personnel (32.1 years old), divided into NG (10) and ExpG (9). The ICA was the outcome variable, with the level of stress and the time of specialization in military tasks as the exposure variables. ICA analysis were carried out based on the cortical areas to compare the ICA of the NG with that of the ExpG. The association of stress level with ICA was estimated by linear regression via linear models.

RESULTS

There was a significant difference in almost all cortical areas, and the averages were always higher in Exp. The high stress level was associated with greater AAP both for the NG and for the ExpG, and at the medium level, the AAP was obtained, varying according to each cortical area.

CONCLUSION

The AAP in ExpG was significantly higher than that in NG, indicating a lower level of cortical activity and greater efficiency in sensory, motor, and visual tasks.

A Prospective Study of Patients with Persistent Symptoms after SARS-CoV-2 Infection Referred to Physical Medicine and Rehabilitation

INTRODUCTION

New evidence and extrapolated data from other coronaviruses suggest that symptoms and consequences of COVID-19 may persist beyond the cure. The aims of this study were to evaluate persistent symptoms after SARS-CoV-2 infection and its impact on physical condition, activities of daily living, and quality-of-life; establish whether symptom persistence is associated with higher disability; and document the evolution of the multiple domains after a home exercise program.

METHODS

Prospective study with patients referred to a Physical and Rehabilitation Medicine clinic, after SARS-CoV-2 infection. Patient evaluations, including a symptom questionnaire, the 1-Min Sit-to-stand test (1-MSTS), the EQ-5D questionnaire and the London Chest Activity Daily Living (LCA-DL) questionnaire, were performed before and after a home exercise program.

RESULTS

Seventy-four patients were included. The majority (n = 71) had been hospitalized (mean stay 19.66 ± 13.35 days), 51% required intensive care. At first evaluation, 54 days after symptom onset, a mean of 18.6 repetitions in the 1-MSTS were performed. The percentage of LCA-DL was above 28% in 23% of the patients. Impairments on EQ-5D were present in 44% for mobility and 44% for anxiety/depression. Mean EQ-5D VAS was 66.5 out of 100. Fifty-one (70%) had at least one persistent symptom (Symptomatic Group), while 22 (30%) were asymptomatic (Asymptomatic Group). The Symptomatic Group had statistically significantly worse mean results on 1-MSTS (16.8 vs 22.9; p < 0.001), % LCA-DL score, EQ-D5 (7.8 vs 5.7; p < 0.001) and EQ-D5-VAS. No patient characteristic, clinical background, comorbidity, or hospitalization characteristics was significantly different between groups. Every patient was given a home exercise program; 47 patients joined an additional rehabilitation program or were clinically discharged and were therefore excluded from the second evaluation. Twenty-seven patients participated in a second evaluation. In the matched analysis, mean 1-MSTS improved by 3.4 repetitions. Mean LCA-DL, mean EQ-5D score (7.1 to 6.6) and EQ-VAS score changed favourably and significantly.

CONCLUSION

Two months after infection by SARS-CoV-2, persistent symptoms were frequent in patients referred to a Physical Medicine and Rehabilitation clinic. Additionally, the SARS-CoV-2 infection, as well as the persistence of symptoms, had a negative impact in the physical condition and functionality in ADL and quality-of-life. With a home exercise program in place, a statistically significant improvement was observed. Referral of patients with persistent symptoms to Physical and Rehabilitation Medicine may be warranted.

Differences between hemispheres and in saccade latency regarding volleyball athletes and non-athletes during saccadic eye movements: an analysis using EEG

BACKGROUND

The saccadic eye movement is responsible for providing focus to a visual object of interest to the retina. In sports like volleyball, identifying relevant targets quickly is essential to a masterful performance. The training improves cortical regions underlying saccadic action, enabling more automated processing in athletes.

OBJECTIVE

We investigated changes in the latency during the saccadic eye movement and the absolute theta power on the frontal and prefrontal cortices during the execution of the saccadic eye movement task in volleyball athletes and non-athletes. We hypothesized that the saccade latency and theta power would be lower due to training and perceptual-cognitive enhancement in volleyball players.

METHODS

We recruited 30 healthy volunteers: 15 volleyball athletes (11 men and 4 women; mean age: 15.08 ± 1.06 years) and 15 non-athletes (5 men and 10 women; mean age: 18.00 ± 1.46 years). All tasks were performed simultaneously with electroencephalography signal recording.

RESULTS

The latency of the saccadic eye movement presented a significant difference between the groups; a shorter time was observed among the athletes, associated with the players' superiority in terms of attention level. During the experiment, the athletes observed a decrease in absolute theta power compared to non-athletes on the electrodes of each frontal and prefrontal area.

CONCLUSION

In the present study, we observed the behavior of reaction time and absolute theta power in athletes and non-athletes during a saccadic movement task. Our findings corroborate the premise of cognitive improvement, mainly due to the reduction of saccadic latency and lower beta power, validating the neural efficiency hypothesis.

Acute kidney injury: a strong risk factor for hypoglycaemia in hospitalized patients with type 2 diabetes

AIMS

Acute kidney injury (AKI) is highly prevalent during hospitalization of patients with type 2 diabetes (T2D). We aimed to assess the impact of AKI and its severity and duration on the risk of hypoglycaemia in hospitalized patients with T2D.

METHODS

Retrospective cohort analysis of patients with T2D, admitted at a University Hospital in 2018-2019. AKI was defined as an increase in serum creatinine by ≥ 0.3 mg/dl (48 h) or ≥ 1.5 times baseline (7 days), and hypoglycaemia as blood glucose concentration < 70 mg/dl. Patients with chronic kidney disease stage ≥ 4 were excluded. We registered 239 hospitalizations with AKI and randomly selected 239 without AKI (control). Multiple logistic regression was used to adjust for confounding factors and ROC curve analysis to determine a cutoff for AKI duration.

RESULTS

The risk of hypoglycaemia was higher in the AKI group (crude OR 3.6, 95%CI 1.8-9.6), even after adjusting for covariates (OR 4.2, 95%CI 1.8-9.6). Each day of AKI duration was associated with a 14% increase in the risk of hypoglycaemia (95%CI 1.1-1.2), and a cutoff of 5.5 days of AKI duration was obtained for increased risk of hypoglycaemia and mortality. AKI severity was also associated with mortality, but showed no significant association with hypoglycaemia. Patients with hypoglycaemia had 4.4 times greater risk of mortality (95%CI 2.4-8.2).

CONCLUSIONS

AKI increased the risk of hypoglycaemia during hospitalization of patients with T2D, and its duration was the main risk factor. These results highlight the need for specific protocols to avoid hypoglycaemia and its burden in patients with AKI.

Magnon Interference Tunneling Spectroscopy as a Probe of 2D Magnetism

Probing two-dimensional single-layer quantum magnets remains a significant challenge. In this Letter, we propose exploiting tunneling spectroscopy in the presence of magnetic impurities to obtain information about the magnon dispersion relations in analogy to quasiparticle interference in nonmagnetic materials. We show that this technique can be used to establish the dispersion relations even for frustrated magnets, where the presence of an impurity generally leads to a nontrivial spin texture. Finally, we consider the problem of establishing Chern magnon bands in 2D magnets showing how tunable impurities allow one to probe the nature of the surface states.

COVID-19 Detection by Means of ECG, Voice, and X-ray Computerized Systems: A Review

Since the beginning of 2020, Coronavirus Disease 19 (COVID-19) has attracted the attention of the World Health Organization (WHO). This paper looks into the infection mechanism, patient symptoms, and laboratory diagnosis, followed by an extensive assessment of different technologies and computerized models (based on Electrocardiographic signals (ECG), Voice, and X-ray techniques) proposed as a diagnostic tool for the accurate detection of COVID-19. The found papers showed high accuracy rate results, ranging between 85.70% and 100%, and F1-Scores from 89.52% to 100%. With this state-of-the-art, we concluded that the models proposed for the detection of COVID-19 already have significant results, but the area still has room for improvement, given the vast symptomatology and the better comprehension of individuals' evolution of the disease.

An intersectionality approach to Indigenous oral health inequities; the super-additive impacts of racism and negative life events

OBJECTIVES

Indigenous Australians experience cumulative forms of oppression. Using intersectionality as the underlying analytical framework, and with oral health as an outcome, we demonstrate how oppressions are interlinked and cannot be treated in isolation. The study aimed to quantify the cumulative effect of two forms of oppression on Indigenous Australian oral health inequities.

METHODS

This observational study was conducted Feb 2018-Jan 2020. Recruitment occurred through Aboriginal Community Controlled Health Organisations in South Australia, Australia. Eligibility included identifying as Indigenous, residing in South Australia and aged 18+ years. Socio-demographic factors, health-related characteristics, experience of racism, negative life events and self-reported oral health outcomes were collected. The main outcomes were fair/poor self-rated oral health and oral health related quality of life, measured by OHIP-14. Effect-measure modification was used to verify differences on effect sizes per strata of negative life events and racism. The presence of modification was indicated by Relative Excess Risk due to Interactions (RERIs).

RESULTS

Data were obtained for 1,011 participants, median age 37 years, 66% female and 63% residing in non-metropolitan locations. Over half (52%) had experienced racism in the past 12 months and 85% had experienced one or more negative life events. Around one-third (34%) rated their oral health as fair/poor and the mean OHIP-14 score was 17. A higher proportion of participants who had experienced both racism and negative life events (46%) were male (52%), aged 37+ years (47%), resided in metropolitan locations (57%), reported difficulty paying a $100 dental bill (47%), had fair/poor self-rated oral health (54%) and higher mean OHIP-14 scores (20). The RERIs observed were 0.31 for fair/poor self-rated oral health and 0.23 for mean OHIP-14. The positive RERIs indicated a super-additive effect between racism, negative life events (effect modifier) and self-reported oral health outcomes.

CONCLUSION

The more oppressions participants experienced, in the form of racism and negative life events, the greater the burden of poor self-reported oral health. The study is one of the first to use intersectionality as a theory to explain oral health inequities as experienced by Indigenous Australians.

Breast Cancer Survivors and Healthy Women: Could Gut Microbiota Make a Difference?-"BiotaCancerSurvivors": A Case-Control Study

In this first analysis, samples from 23 BC survivors (group 1) and 291 healthy female controls (group 2) were characterised through the V3 and V4 regions that encode the "16S rRNA" gene of each bacteria. The samples were sequenced by next-generation sequencing (NGS), and the taxonomy was identified by resorting to Kraken2 and improved with Bracken, using a curated database called 'GutHealth_DB'. The α and β-diversity analyses were used to determine the richness and evenness of the gut microbiota. A non-parametric Mann-Whitney U test was applied to assess differential abundance between both groups. The Firmicutes/Bacteroidetes (F/B) ratio was calculated using a Kruskal-Wallis chi-squared test. The α-diversity was significantly higher in group 1 (p = 0.28 × 10^-12 for the Chao index and p = 1.64 × 10^-12 for the ACE index). The Shannon index, a marker of richness and evenness, was not statistically different between the two groups (p = 0.72). The microbiota composition was different between the two groups: a null hypothesis was rejected for PERMANOVA (p = 9.99 × 10^-5) and Anosim (p = 0.04) and was not rejected for β-dispersion (p = 0.158), using Unifrac weighted distance. The relative abundance of 14 phyla, 29 classes, 25 orders, 64 families, 116 genera, and 74 species differed significantly between both groups. The F/B ratio was significantly lower in group 1 than in group 2, p < 0.001. Our study allowed us to observe significant taxonomic disparities in the two groups by testing the differences between BC survivors and healthy controls. Additional studies are needed to clarify the involved mechanisms and explore the relationship between microbiota and BC survivorship.

Distinction of Different Colony Types by a Smart-Data-Driven Tool

BACKGROUND

Colony morphology (size, color, edge, elevation, and texture), as observed on culture media, can be used to visually discriminate different microorganisms.

METHODS

This work introduces a hybrid method that combines standard pre-trained CNN keras models and classical machine-learning models for supporting colonies discrimination, developed in Petri-plates. In order to test and validate the system, images of three bacterial species (Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus) cultured in Petri plates were used.

RESULTS

The system demonstrated the following Accuracy discrimination rates between pairs of study groups: 92% for Pseudomonas aeruginosa vs. Staphylococcus aureus, 91% for Escherichia coli vs. Staphylococcus aureus and 84% Escherichia coli vs. Pseudomonas aeruginosa.

CONCLUSIONS

These results show that combining deep-learning models with classical machine-learning models can help to discriminate bacteria colonies with good accuracy ratios.

Impact of Beer and Nonalcoholic Beer Consumption on the Gut Microbiota: A Randomized, Double-Blind, Controlled Trial

Gut microbiota modulation might constitute a mechanism mediating the effects of beer on health. In this randomized, double-blinded, two-arm parallel trial, 22 healthy men were recruited to drink 330 mL of nonalcoholic beer (0.0% v/v) or alcoholic beer (5.2% v/v) daily during a 4-week follow-up period. Blood and faecal samples were collected before and after the intervention period. Gut microbiota was analyzed by 16S rRNA gene sequencing. Drinking nonalcoholic or alcoholic beer daily for 4 weeks did not increase body weight and body fat mass and did not changed significantly serum cardiometabolic biomarkers. Nonalcoholic and alcoholic beer increased gut microbiota diversity which has been associated with positive health outcomes and tended to increase faecal alkaline phosphatase activity, a marker of intestinal barrier function. These results suggest the effects of beer on gut microbiota modulation are independent of alcohol and may be mediated by beer polyphenols.

Anxiety, insomnia, and depression during COVID-19 lockdown in elite individual and team sport athletes

PURPOSE

Pandemic-induced lockdowns disrupted sport training and competition. We aimed to identify the impact on the mental health of high-level athletes and clarify whether the effects differ for team-based and individual athletes.

METHODS

This cross-sectional survey, stratified by sex and sport type, collected demographic data and mental health measurements from 274 Brazilian high-performance athletes (142 from team sports and 132 from individual sports) involved with the Brazilian Olympic Committee program for the Tokyo Olympics 2021. Depression, disturbed sleep, and anxiety were assessed by the 9-Item Patient Health Questionnaire, 7-Item Insomnia Severity Index, and 7-Item Generalized Anxiety Disorder scale respectively. Responses were analyzed dichotomously according to published threshold values, characterizing the relative frequency distribution of prevalence (PCRS) or non-prevalence of clinically relevant symptoms (NPCRS).

RESULTS

Out of all participants, 47 [17.1%], Z(274) = 15.38, p = .001, 32 [11.7%], Z(274) = 17.94, p = .001, and 49 [17.9%], Z(274) = 15.04, p = .001 had PCRS of anxiety, insomnia, and depression, respectively. There were no significant differences in the PCRS among genders. Compared with individual sport athletes, team sport athletes were more likely to report PCRS of insomnia (12 [37.5%] vs 20 [62.5%], Z(274) = -2.00, p = .046), and depression (18 [36.7%] vs 31 [63.3%], Z(274) = -2.63, p = .009) but not for anxiety.

CONCLUSION

Athletes reported high levels of mental health problems during the lockdown. Team sport athletes reported worse symptoms of insomnia and depression than individual sport athletes, possibly due to the impact of unaccustomed social isolation and lack of social team activity. Therefore, it becomes relevant to consider psychological support to team sport athletes who for some reason, such as a pandemic, enduring crisis even injury rehabilitation needs to be isolated.

Open monitoring meditation alters the EEG gamma coherence in experts meditators: The expert practice exhibit greater right intra-hemispheric functional coupling

AIM

This study investigated the differences in frontoparietal EEG gamma coherence between expert meditators (EM) and naïve meditators (NM).

MATERIAL AND METHODS

This is a cross-sectional study with a sample of twenty-one healthy adults divided under two groups (experts meditators vs. naive-meditators), with analyzing the intra-hemispheric coherence of frontoparietal gamma oscillations by electroencephalography during the study steps: EEG resting-state 1, during the open presence meditation practice, and EEG resting-state 2.

RESULTS

The findings demonstrated greater frontoparietal EEG coherence in gamma for experts meditators in the Fp1-P3, F4-P4, F8-P4 electrode pairs during rest 1 and rest 2 (p ≤ 0.0083). In addition, we evidenced differences in the frontoparietal EEG coherence for expert meditators in F4-P4, F8-P4 during the meditation (p ≤ 0.0083).

CONCLUSION

Our results can support evidence that the connectivity of the right frontoparietal network acts as a biomarker of the enhanced Open monitoring meditation training.

Novel features for time series analysis: a complex networks approach

Being able to capture the characteristics of a time series with a feature vector is a very important task with a multitude of applications, such as classification, clustering or forecasting. Usually, the features are obtained from linear and nonlinear time series measures, that may present several data related drawbacks. In this work we introduce NetF as an alternative set of features, incorporating several representative topological measures of different complex networks mappings of the time series. Our approach does not require data preprocessing and is applicable regardless of any data characteristics. Exploring our novel feature vector, we are able to connect mapped network features to properties inherent in diversified time series models, showing that NetF can be useful to characterize time data. Furthermore, we also demonstrate the applicability of our methodology in clustering synthetic and benchmark time series sets, comparing its performance with more conventional features, showcasing how NetF can achieve high-accuracy clusters. Our results are very promising, with network features from different mapping methods capturing different properties of the time series, adding a different and rich feature set to the literature.

Fratura isolada de Tillaux em adulto – Revisão da Literatura com base em um relato de caso raro

A fratura isolada de Tillaux representa uma rara e frequentemente mal diagnosticada fratura de tíbia distal anterolateral em adultos. Normalmente ocorre em adolescentes que se aproximam da maturidade esquelética por avulsão do ligamento tibiofibular anteroinferior. Este estudo de revisão de literatura baseada em caso tem como objetivo lembrar a existência dessa identidade em adultos, resumir seu mecanismo de lesão, diagnóstico e procedimentos de tratamento. De acordo com a literatura, este é apenas o oitavo caso descrito: uma mulher de 46 anos sofreu uma fratura isolada de Tillaux com 4 mm de deslocamento e realizaram-se redução e fixação aberta com parafuso canulado duplo. Após a reabilitação adequada, alcançou-se um excelente desfecho funcional e radiológico. É importante reconhecer e tratar adequadamente essas lesões distintas para evitar maiores instabilidades, alterações degenerativas e limitação da função articular do tornozelo. Um diagnóstico precoce e a osteossíntese apropriada desempenham um papel significativo em um prognóstico de recuperação bem-sucedido.

Primary Adrenal Lymphoma: When B Symptoms Appear Hand in Hand with Adrenal Masses

Primary adrenal lymphoma (PAL) is a very rare type of non-Hodgkin’s lymphoma (NHL). Herein, we report a case of NHL of both adrenal glands in a 69-year-old man. The patient was admitted because of a 1-month history of B symptoms and symptomatic hypotension. Biochemical analysis showed normocytic normochromic anaemia, hyponatraemia, hyperkalaemia, and elevated lactate dehydrogenase, C-reactive protein and D-dimers. A computed tomography scan revealed bilateral enlargement of the adrenal glands. There was no evidence of endocrine adrenal dysfunction. The mass in the right adrenal gland was biopsied and histopathology identified a diffuse large B-cell lymphoma of the activated B-cell subtype. A positron emission tomography 18F-fluorodeoxyglucose scan showed intensive hypermetabolic lesions involving both adrenal glands, as well as other locations, with higher uptake in the adrenal glands. Taken together, these findings suggested the diagnosis of PAL. The patient responded favourably to debulking therapy and is currently undergoing chemotherapy.

Can mental practice adjunct in the recovery of motor function in the upper limbs after stroke? A systematic review and meta-analysis

BACKGROUND:

Studies indicate that mental practice can be an adjuvant rehabilitation, improving motor functions.

AIM:

To synthesize the evidence on the intervention with the mental practice for the rehabilitation of the upper limb after stroke in the context of a dependent task.

METHODS:

The review was registered on the PROSPERO with protocol number: CRD42020166624. We searched the PubMed, Medline, Embase, Central, PEDro, and Web of Science from randomized clinical trials from 1975 to 2022. A literature review was conducted with 13 studies that synthesized findings on mental practice such as adjuvant rehabilitation in the recovery of the upper limb after stroke based on Fugl-Meyer Assessment (FMA) Motor and action research arm test (ARAT) scores.

RESULTS:

The sample size was 232 were part of the intervention group and 180 of the control group. The findings no showed results in favor of mental practice after stroke accordingly to ARAT and FMA Motor scores (P > 0.05).

CONCLUSION:

Current evidence does not support the use of the mental practice to increase the recovery of the upper limb after stroke, although the evidence is conflicting for some aspects of the technique.

Male practitioners of physical activity present lower absolute power of beta band in time perception test

Cortical changes resulting from physical activity and differences in the estimation of the time of practitioners and non-practitioners of physical activity have already been documented. However, there aren't studies that compare the cortical responses of the time estimate between these groups. Therefore, this study aimed to investigate the influence of the level of physical activity in time estimation and beta band activity in frontal regions, specifically in the dorsolateral prefrontal cortex, ventrolateral prefrontal cortex, and parietal cortex during the task of estimating time in practitioners and non-practitioners of physical activity. After characterizing the sample, the signal was captured using an electroencephalogram during a task to estimate the time of four intervals of supraseconds. The results indicated that the practitioners of physical activity had lower errors in the evaluation of time for the intervals of 1 s, 7 s, and 9 s. The beta band showed less activity among practitioners of physical activity. The correlation between task performance and the absolute power of the beta band proved to be positive in the task of estimating time in the 7 s, and 9 s intervals. It was concluded that participants involved in the regular practice of physical activity showed underestimation in the temporal judgment and lower absolute power of the beta band during the time estimate.

The aftermath of hip fragility fractures - are we missing out on osteoporosis treatment?"

INTRODUCTION

Fragility fractures cause significant mortality and morbidity. Even though there are multiple guidelines for the management of fragility fractures, european countries still report treatment rates of less than 30%. Implementation of fracture liaison services can increase this percentage by 21%. Our goal is to describe the management of osteoporosis, in patients with hip fragility fracture treated in a portuguese hospital with no internal protocols in place.

METHODS

A retrospective study was conducted. Patients treated surgically for hip fragility fracture in our hospital, during 2017, were included. Data until May 2020 was collected on osteoporosis recognition and pharmacological treatment prescription.

RESULTS

A total of 102 patients were included, 87% female, with a mean age of 79.9±9.9 years at the time of the fracture. Pharmacological anti-osteoporotic treatment after the hip fragility fracture was prescribed in 35%. From those, 53% did not include bisphosphonates. General practice doctors were responsible for 44% of anti-osteoporotic prescriptions and "Osteoporosis" ICD10 codification in primary care was present in 10.7%.

DISCUSSION/CONCLUSION

We found a gap in osteoporosis treatment after a hip fragility fracture, similar to literature reports when no fracture liaison service is in place. We believe that the lack of such protocols, the low rate of "osteoporosis" or "fragility fracture" mentioning at hospital discharge, together with the under recognition at primary care level, contribute to this reality. The implementation of new measures is crucial to improve prevention and management of fragility fractures.

Rickettsial fever leading to upper disphagya: A rare neurovascular conflict between vertebral artery and glossopharyngeal nerve

Rickettsial fevers are a common type of zoonosis with potential neurological involvement, mostly in form of meningoencephalitis. However, there are some rare cases that could compromise cranial nerves function through vascular inflammation. In this paper, we describe a rare case of dysphagia related to glossopharyngeal involvement by juxtaposed vertebral artery vasculitis.

Gut Microbiota Diversity and C-Reactive Protein Are Predictors of Disease Severity in COVID-19 Patients

The risk factors for coronavirus disease 2019 (COVID-19) severity are still poorly understood. Considering the pivotal role of the gut microbiota on host immune and inflammatory functions, we investigated the association between changes in the gut microbiota composition and the clinical severity of COVID-19. We conducted a multicenter cross-sectional study prospectively enrolling 115 COVID-19 patients categorized according to: (1) the WHO Clinical Progression Scale-mild, 19 (16.5%); moderate, 37 (32.2%); or severe, 59 (51.3%), and (2) the location of recovery from COVID-19-ambulatory, 14 (household isolation, 12.2%); hospitalized in ward, 40 (34.8%); or hospitalized in the intensive care unit, 61 (53.0%). Gut microbiota analysis was performed through 16S rRNA gene sequencing, and the data obtained were further related to the clinical parameters of COVID-19 patients. The risk factors for COVID-19 severity were identified by univariate and multivariable logistic regression models. In comparison to mild COVID-19 patients, the gut microbiota of moderate and severe patients have: (a) lower Firmicutes/Bacteroidetes ratio; (b) higher abundance of Proteobacteria; and (c) lower abundance of beneficial butyrate-producing bacteria such as the genera Roseburia and Lachnospira. Multivariable regression analysis showed that the Shannon diversity index [odds ratio (OR) = 2.85, 95% CI = 1.09-7.41, p = 0.032) and C-reactive protein (OR = 3.45, 95% CI = 1.33-8.91, p = 0.011) are risk factors for severe COVID-19 (a score of 6 or higher in the WHO Clinical Progression Scale). In conclusion, our results demonstrated that hospitalized patients with moderate and severe COVID-19 have microbial signatures of gut dysbiosis; for the first time, the gut microbiota diversity is pointed out as a prognostic biomarker of COVID-19 severity.

Cerebral Venous Thrombosis and Its Clinical Diversity

Cerebral venous thrombosis (CVT) is a serious medical condition which is difficult to diagnose because of its wide range of clinical presentations. The symptoms can vary from an isolated headache to coma. Here, we present the case of a 76-year-old female patient with a history of immune thrombocytopenic purpura, arterial hypertension, and pulmonary embolism. The diagnosis of CVT was challenging because the initial form of disease presentation mimicked a transient ischemic attack (transient aphasia and right hemiparesis). Therapeutical decisions were also a challenge because, at the time of the diagnosis, the patient was suffering from severe thrombocytopenia (29 × 10⁹/L), which had to be taken into account. After multidisciplinary discussions, therapeutic subcutaneous enoxaparin was started, resulting in a progressive and significant neurological recovery. In presenting this case, our primary goal is to point out that CVT can be difficult to diagnose because of its wide range of clinical presentations. Headache (a symptom that was never present in this case) is the most frequent complaint, occurring in 90% of cases. Following diagnosis, an etiological study is required.

A Pilot Study on the Metabolic Impact of Mediterranean Diet in Type 2 Diabetes: Is Gut Microbiota the Key?

The Mediterranean diet (MD) has been recommended for type 2 diabetes (T2D) treatment. The impact of diet in shaping the gut microbiota is well known, particularly for MD. However, the link between MD and diabetes outcome improvement is not completely clear. This study aims to evaluate the role of microbiota modulation by a nonpharmacological intervention in patients with T2D. In this 12-week single-arm pilot study, nine participants received individual nutritional counseling sessions promoting MD. Gut microbiota, biochemical parameters, body composition, and blood pressure were assessed at baseline, 4 weeks, and 12 weeks after the intervention. Adherence to MD [assessed by Mediterranean Diet Adherence Screener (MEDAS) score] increased after the intervention. Bacterial richness increased after 4 weeks of intervention and was negatively correlated with fasting glucose levels and Homeostatic Model Assessment for Insulin Resistance (HOMA-IR). Prevotella to Bacteroides ratio also increased after 4 weeks. In contrast, glycated haemoglobin (HbA1c) and HOMA-IR were only decreased at the end of study. Alkaline phosphatase activity was assessed in fecal samples and was negatively correlated with HbA1c and positively correlated with bacterial diversity. The results of this study reinforce that MD adherence results in a better glycemic control in subjects with T2D. Changes in gut bacterial richness caused by MD adherence may be relevant in mediating the metabolic impact of this dietary intervention.

Repetitive transcranial magnetic stimulation changes cognitive/motor tasks performance: An absolute alpha and beta power study

The voluntary movement demands integration between cognitive and motor functions. During the initial stages of motor learning until mastery of a new motor task, and during a demanding task that is not automatic, cognitive and motor functions can be perceived as independent from each other. Areas used for actually performing motor tasks are essentially the same used by Motor Imagery (MI). The main objective of this study was to investigate inhibition effects on cognitive functions of motor skills induced by low-frequency (1 Hz) Repetitive Transcranial Magnetic Stimulation (rTMS) at the sensory-motor integration site (Cz). In particular, the goal was to examine absolute alpha and beta power changes on frontal regions during Execution, Action observation, and Motor Imagery of finger movement tasks. Eleven healthy, right-handed volunteers of both sexes (5 males, 6 females; mean age 28 ± 5 years), with no history of psychiatric or neurological disorders, participated in the experiment. The execution task consisted of the subject flexing and extending the index finger. The action observation task involved watching a video of the same movement. The motor imagery task was imagining the flexion and extension of the index finger movement. After performing the tasks randomly, subjects were submitted to 15 min of low-frequency rTMS and performed the tasks again. All tasks were executed simultaneously with EEG signals recording. Our results demonstrated a significant interaction between rTMS and the three tasks in almost all analyzed regions showing that rTMS can affect the frontal region regarding Execution, Action observation, and Motor Imagery tasks.

Individual versus task differences in slow potential generators

Average slow potentials (SPs) can be computed from any voluntary task, minimally involving attention to anticipated stimuli. Their topography when recorded by large electrode arrays even during simple tasks is complex, multifocal, and its generators appear to be equally multifocal and highly variable across subjects. Various sources of noise of course contaminate such averages and must contribute to the topographic complexity. Here, we report a study in which the non-averaged SP band (0 to 1 Hz) was analyzed by independent components (ICA), from 256 channel recordings of 18 subjects, during four task conditions (resting, visual attention, CPT, and Stroop). We intended to verify whether the replicable SP generators (between two separate day sessions) modeled as current density reconstruction on structural MRI sets were individual-specific, and if putative task-related differences were systematic across subjects. Typically, 3 ICA components (out of 10) explained SPs in each task and subject, and their combined generators were highly variable across subjects: although some occipito-temporal and medial temporal areas contained generators in most subjects; the overall patterns were obviously variable, with no single area common to all 18 subjects. Linear regression modeling to compare combined generators (from all ICA components) between tasks and sessions showed significantly higher correlations between the four tasks than between sessions for each task. Moreover, it was clear that no common task-specific areas could be seen across subjects. Those results represent one more instance in which individual case analyses favor the hypothesis of individual-specific patterns of cortical activity, regardless of task conditions. We discuss this hypothesis with respect to results from the beta band, from individual-case fMRI studies, and its corroboration by functional neurosurgery and the neuropsychology of focal lesions.

Event-related potential (P300): the effects of levetiracetam in cognitive performance

BACKGROUND

The current study is a reanalysis in the time domain of EEG data collection in healthy adults during an oddball paradigm using levetiracetam (LEV) vs. placebo acute administration. Specifically, the event-related potential (ERP) technique provides a tool for exploring the EEG responses to a specific event/stimulus. One of the ERP components widely studied is the P300 component, which is associated with the last stage of information processing and a general measurement of "cognitive efficiency."

METHODS

The sample was composed of thirteen healthy right-handed individuals randomized to participate under two conditions: LEV and placebo. Electrophysiological measures were collected before and after drug intake. We explored the oddball paradigm, which is commonly used with healthy individuals to investigate the stages of information processing.

RESULTS

The electrophysiological results showed a main effect of condition on P300 amplitude for the frontal (F3, Fz, F4), central (C3, Cz, C4), and parietal electrodes (P3, Pz, P4). The post hoc comparisons (Scheffé's test) demonstrated the significant differences between electrodes. Regarding P300 latency, all regions represented a main effect of condition. A P300 latency reduction was observed during LEV condition compared with placebo.

CONCLUSION

Our study observed the ERP component-P300-through the variation of its amplitude and latency to evaluate a supposed higher CNS efficiency when participants were under the LEV effect. Our findings sustain this premise, mainly due to reducing in P300 latency for the LEV condition, supporting the neural efficiency hypothesis.

Unskilled shooters improve both accuracy and grouping shot having as reference skilled shooters cortical area: An EEG and tDCS study

Transcranial direct current stimulation (tDCS) has been used as a non-invasive method for enhanced motor and cognitive abilities. However, no previous study has investigated if the tDCS application in unskilled shooters on cortical sites, selected based on the cortical activity of skilled shooters, improves the accuracy and shot grouping. Sixty participants were selected, which included 10 skilled shooters and 50 unskilled shooters. After we identified the right dorsolateral prefrontal cortex (DLPFC) as the area with the highest activity in skilled shooters, we applied anodal tDCS over the right DLPFC in the unskilled shooters under two conditions: sham-tDCS (placebo) and real-tDCS (anodal tDCS). We also analyzed electroencephalography. Our results indicated that anodal tDCS application enhanced the shot accuracy (p = 0.001). Furthermore, the beta power in the EEG recording was higher in the left DLPFC, left and right parietal cortex (p = 0,001) after applying anodal tDCS, while the low-gamma power was higher in the right DLPFC in sham-tDCS (p = 0.001) and right parietal cortex after anodal-tDCS (p = 0.001). Our findings indicate that anodal tDCS can improve accuracy and shot grouping when applied over the unskilled shooters' right DLPFC. Furthermore, beta and low-gamma bands are influenced by anodal tDCS over the right DLPFC, which may be predictive of skill improvement.

Spine Cop: Posture Correction Monitor and Assistant

Back and spine-related issues are frequent maladies that most people have or will experience during their lifetime. A common and sensible observation that can be made is regarding the posture of an individual. We present a new approach that combines accelerometer, gyroscope, and magnetometer sensor data in combination with permanent magnets assembled as a wearable device capable of real-time spine posture monitoring. An independent calibration of the device is required for each user. The sensor data is processed by a probabilistic classification algorithm that compares the real-time data with the calibration result, verifying whether the data point lies within regions of confidence defined by a computed threshold. An incorrect posture classification is considered if both accelerometer and magnetometer classify the posture as incorrect. A pilot trial was performed in a single adult test subject. The combination of the magnets and magnetometer greatly improved the posture classification accuracy (89%) over the accuracy obtained when only accelerometer data were used (47%). The validation of this method was based on image analysis.

PseudoChecker: an integrated online platform for gene inactivation inference

The rapid expansion of high-quality genome assemblies, exemplified by ongoing initiatives such as the Genome-10K and i5k, demands novel automated methods to approach comparative genomics. Of these, the study of inactivating mutations in the coding region of genes, or pseudogenization, as a source of evolutionary novelty is mostly overlooked. Thus, to address such evolutionary/genomic events, a systematic, accurate and computationally automated approach is required. Here, we present PseudoChecker, the first integrated online platform for gene inactivation inference. Unlike the few existing methods, our comparative genomics-based approach displays full automation, a built-in graphical user interface and a novel index, PseudoIndex, for an empirical evaluation of the gene coding status. As a multi-platform online service, PseudoChecker simplifies access and usability, allowing a fast identification of disruptive mutations. An analysis of 30 genes previously reported to be eroded in mammals, and 30 viable genes from the same lineages, demonstrated that PseudoChecker was able to correctly infer 97% of loss events and 95% of functional genes, confirming its reliability. PseudoChecker is freely available, without login required, at http://pseudochecker.ciimar.up.pt.

Temporal network alignment via GoT-WAVE

MOTIVATION

Network alignment (NA) finds conserved regions between two networks. NA methods optimize node conservation (NC) and edge conservation. Dynamic graphlet degree vectors are a state-of-the-art dynamic NC measure, used within the fastest and most accurate NA method for temporal networks: DynaWAVE. Here, we use graphlet-orbit transitions (GoTs), a different graphlet-based measure of temporal node similarity, as a new dynamic NC measure within DynaWAVE, resulting in GoT-WAVE.

RESULTS

On synthetic networks, GoT-WAVE improves DynaWAVE's accuracy by 30% and speed by 64%. On real networks, when optimizing only dynamic NC, the methods are complementary. Furthermore, only GoT-WAVE supports directed edges. Hence, GoT-WAVE is a promising new temporal NA algorithm, which efficiently optimizes dynamic NC. We provide a user-friendly user interface and source code for GoT-WAVE.

AVAILABILITY AND IMPLEMENTATION

http://www.dcc.fc.up.pt/got-wave/.

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

Dopaminergic drugs alter beta coherence during motor imagery and motor execution in healthy adults

BACKGROUND

Motor Imagery (MI) represents the cognitive component of the movement and recruits dopaminergic systems.

OBJECTIVE

To investigate the role of dopaminergic system through the action of methylphenidate and risperidone over beta coherence during execution, action observation and motor imagery.

METHODS

Electroencephalography (EEG) data were recorded before and after the substance intake. For statistical analysis, a three-way ANOVA was used to identify changes in beta coherence induced by the group, task and the moment variables. Statistical significance was set at p≤0.007.

RESULTS

We found a main effect for group for C3/CZ, and a main effect for task for CZ/C4 pairs of electrodes. Furthermore, significant differences were found in the post-drug administration between groups for C3/CZ pair of electrodes, and between task for C4/CZ pair of electrodes.

CONCLUSION

The administration of methylphenidate and risperidone was able to produce electrocortical changes of the cortical central regions, even when featuring antagonistic effects on the dopaminergic pathways. Moreover, the execution task allowed beta-band modulation increase.

Disorder-Driven Multifractality Transition in Weyl Nodal Loops

The effect of short-range disorder in nodal line semimetals is studied by numerically exact means. For arbitrary small disorder, a novel semimetallic phase is unveiled for which the momentum-space amplitude of the ground-state wave function is concentrated around the nodal line and follows a multifractal distribution. At a critical disorder strength, a semimetal to compressible metal transition occurs, coinciding with a multi- to single-fractality transition. The universality class of this critical point is characterized by the correlation length and dynamical exponents. At considerably higher disorder, an Anderson metal-insulator transition takes place. Our results show that the nature of the semimetallic phase in nonclean samples is fundamentally different from a clean nodal semimetal.

Many-Body Quantum Dynamics of Initially Trapped Systems due to a Stark Potential: Thermalization versus Bloch Oscillations

We analyze the dynamics of an initially trapped cloud of interacting quantum particles on a lattice under a linear (Stark) potential. We reveal a dichotomy: initially trapped interacting systems possess features typical of both many-body-localized and thermalizing systems. We consider both fermions (t-V model) and bosons (Bose-Hubbard model). For the zero and infinite interaction limits, both systems are integrable: we provide analytic solutions in terms of the moments of the initial cloud shape and clarify how the recurrent dynamics (many-body Bloch oscillations) depends on the initial state. Away from the integrable points, we identify and explain the timescale at which Bloch oscillations decohere.

Safety Assurance of a High Voltage Controller for an Industrial Robotic System

Due to the risk of discharge sparks and ignition, there are strict rules concerning the safety of high voltage electrostatic systems used in industrial painting robots. In order to assure that the system fulfils its safety requirements, formal verification is an important tool to supplement traditional testing and quality assurance procedures. The work in this paper presents formal verification of the most important safety functions of a high voltage controller. The controller has been modelled as a finite state machine, which was formally verified using two different model checking software tools; Simulink Design Verifier and RoboTool. Five safety critical properties were specified and formally verified using the two tools. Simulink was chosen as a low-threshold entry point since MathWorks products are well known to most practitioners. RoboTool serves as a software tool targeted towards model checking, thus providing more advanced options for the more experienced user. The comparative study and results show that all properties were successfully verified. The verification times in both tools were in the order of a few minutes, which was within the acceptable time limit for this particular application.

Hemodynamic differences among hypertensive patients with and without heart failure using impedance cardiography

Background:

Impedance cardiography is a reliable, well-tolerated, and non-invasive method used to obtain hemodynamic measurements and could potentially be useful in heart failure (HF) diagnosis, hemodynamic monitoring of critically ill patients, and help in the choice of antihypertensive therapy. The objective of this study was to determine the differences between hemodynamic parameters in a study population of hypertensive patients with and without HF, using impedance cardiography.

Methods:

A case-control study was designed and named the TARGET study. Participants were enrolled in two study groups: control group C, hypertensive patients without HF and the HF group, hypertensive patients with HF. A descriptive analysis was carried out to characterize the sample and differences in continuous variables were tested for statistical significance by independent sample t test.

Results:

The study included 102 hypertensive outpatients. The control group consisted of 77 individuals (58.4% males; mean age 63.9 ± 12.5 years old) and the HF group consisted of 25 individuals (44.0% males; mean age 74.2 ± 8.7 years old). The mean Cardiac Index (CI) was 2.70 ± 1.02 L.min.m⁻² (2.89 ± 1.04 versus 2.12 ± 0.70; p < 0.001), mean Stroke Index (SI) was 35.5 ± 14.7 mL.m⁻² (37.7 ± 15.2 versus 28.5 ± 10.8; p = 0.006), mean Ejection Phase Contractility Index (EPCI) was 33.7 ± 12.7 1000 s⁻² (35.8 ± 13.1 versus 27.2 ± 9.2; p = 0.003), mean Inotropic State Index (ISI) was 74.3 ± 28.2 100 s⁻² (78.8 ± 28.9 versus 60.6 ± 20.7; p = 0.005), and mean Left Stroke Work Index (LSWI) was 51.3 ± 23.1 g.min.m⁻² (55.4 ± 23.5 versus 38.9 ± 16.6; p = 0.002).

Conclusions:

In this study, hypertensive patients with HF had significantly lower values of blood flow parameters, contractility, and left work indices compared with hypertensive patients without HF. These differences reflected the incorrect hemodynamic pattern (mostly hypodynamic) of these patients. Impedance cardiography (ICG) seems to be an adequate method to reflect these differences.

Mixed-Order Symmetry-Breaking Quantum Phase Transition Far from Equilibrium

We study the current-carrying steady state of a transverse field Ising chain coupled to magnetic thermal reservoirs and obtain the nonequilibrium phase diagram as a function of the magnetization potential of the reservoirs. Upon increasing the magnetization bias we observe a discontinuous jump of the magnetic order parameter that coincides with a divergence of the correlation length. For steady states with a nonvanishing conductance, the entanglement entropy at zero temperature displays a bias dependent logarithmic correction that violates the area law and differs from the well-known equilibrium case. Our findings show that out-of-equilibrium conditions allow for novel critical phenomena not possible at equilibrium.

Classical and Quantum Liquids Induced by Quantum Fluctuations

Geometrically frustrated interactions may render classical ground states macroscopically degenerate. The connection between classical and quantum liquids and how the degeneracy is affected by quantum fluctuations is, however, not completely understood. We study a simple model of coupled quantum and classical degrees of freedom, the so-called Falicov-Kimball model, on a triangular lattice and away from half-filling. For weak interactions the phase diagram features a charge disordered state down to zero temperature. We provide compelling evidence that this phase is a liquid and show that it is divided by a crossover line that terminates in a quantum critical point. Our results offer a new vantage point to address how quantum liquids can emerge from their classical counterparts.

Y-TZP/porcelain graded dental restorations design for improved damping behavior - A study on damping capacity and dynamic Young's modulus

The development of dental restorative materials that mimic tooth-like properties provided by graded structures, aesthetics and properties such as strength, damping capacity and the ability for a continuous remodeling according to the biomechanical solicitation is a great challenge. In this work, damping capacity and dynamic Young's modulus of Y-TZP/porcelain composites for all-ceramic dental restorations were studied. These mechanical properties were assessed by dynamic mechanical analyses (DMA) at frequencies of 1, 5 and 10 Hz, over a temperature ranging from 0 to 60 °C, simulating extreme conditions when a cold or hot drink is experienced. The results showed that porcelain and porcelain-matrix composites exhibited higher damping capacity while Y-TZP and Y-TZP-matrix composites presented higher dynamic Young's modulus. Furthermore, while damping capacity is strongly influenced by the temperature, no significant difference in dynamic Young's modulus was found. For both damping and modulus properties, no significant influence of frequency was found for the tested materials. Based on the obtained results and also on the known advantages of the graded Y-TZP/porcelain structures over traditional bi-layer solutions (e.g., improved bending strength, enhanced mechanical and thermal stress distribution), a novel design of all-ceramic restoration with damping capacity has been proposed at the end of this study. A positive impact on the long-term performance of these all-ceramic restorations may be expected.

Temperature-Driven Gapless Topological Insulator

We investigate the phase diagram of the Haldane-Falicov-Kimball model-a model combining topology, interactions, and spontaneous disorder at finite temperatures. Using an unbiased numerical method, we map out the phase diagram on the interaction-temperature plane. Along with known phases, we unveil an insulating charge ordered state with gapless excitations and a temperature-driven gapless topological insulating phase. Intrinsic-temperature-generated-disorder is the key ingredient explaining the unexpected behavior. Our findings support the possibility of having temperature-driven topological transitions into gapped and gapless topological insulating phases in mass unbalanced systems with two fermionic species.

Low Back Pain: A Pain That May Not Be Harmless

Abdominal aortic aneurysms are defined as vascular dilatations greater than 50% of the normal proximal segment or those that have a maximum diameter above 3 cm. Risk factors include male gender, age over 75 years, history of vascular pathology, hypertension and arteriosclerosis. The Authors describe a case of a 74-year-old man, evaluated in an emergency setting for right lumbar pain lasting 4 days. The pain did not respond to analgesia and became progressively worse. Due to the severity of symptoms, CT angiography was performed, which showed an active rupture of a partially contained aneurysm associated with aortic dissection. Early diagnosis and timely management of aortic aneurysms are essential in preventing complications, namely rupture (50–83% patients die after rupture and before receiving medical care). Acute aortic dissection is a surgical emergency and the risk of rupture is proportional to the size of the aneurysm and its rate of growth.

EEG coherence as a diagnostic tool to measure the initial stages of Parkinson Disease

Although Parkinson Disease was described a long time ago by James Parkinson and several biomarkers were used to predict the symptoms of PD, there is no accepted tool to distinguish the initial stages of this pathology. The present hypothesis discusses the Coherence Function, an Electroencephalography measure which could be used as a simple, and low-cost tool to describe the onset of cardinal signals of PD. Our hypothesis is based on three factors: beta frequency related to movement, motor action over particular cortical regions, and cortical coupling between cortical areas involved in the execution of voluntary movement. We believe that these factors support our hypothesis pointing out coherence function as an interesting measure to detect initial stages of PD.

Methylphenidate modifies activity in the prefrontal and parietal cortex accelerating the time judgment

Methylphenidate produces its effects via actions on cortical areas involved with attention and working memory, which have a direct role in time estimation judgment tasks. In particular, the prefrontal and parietal cortex has been the target of several studies to understand the effect of methylphenidate on executive functions and time interval perception. However, it has not yet been studied whether acute administration of methylphenidate influences performance in time estimation task and the changes in alpha band absolute power in the prefrontal and parietal cortex. The current study investigates the influence of the acute use of methylphenidate in both performance and judgment in the time estimation interpretation through the alpha band absolute power activity in the prefrontal and parietal cortex. This is a double-blind, crossover study with a sample of 32 subjects under control (placebo) and experimental (methylphenidate) conditions with absolute alpha band power analysis during a time estimation task. We observed that methylphenidate does not influence task performance (p > 0.05), but it increases the time interval underestimation by over 7 s (p < 0.001) with a concomitant decrease in absolute alpha band power in the ventrolateral prefrontal cortex and dorsolateral prefrontal cortex and parietal cortex (p < 0.001). Acute use of methylphenidate increases the time interval underestimation, consistent with reduced accuracy of the internal clock mechanisms. Furthermore, acute use of methylphenidate influences the absolute alpha band power over the dorsolateral prefrontal cortex, ventrolateral prefrontal cortex, and parietal cortex.

Integrable Quantum Dynamics of Open Collective Spin Models

We consider a collective quantum spin s in contact with Markovian spin-polarized baths. Using a conserved superoperator charge, a differential representation of the Liouvillian is constructed to find its exact spectrum and eigenmodes. We study the spectral properties of the model in the large-s limit using a semiclassical quantization condition and show that the spectral density may diverge along certain curves in the complex plane. We exploit our exact solution to characterize steady-state properties, in particular at the discontinuous phase transition that arises for unpolarized environments, and to determine the decay rates of coherences and populations. Our approach provides a systematic way of finding integrable Liouvillian operators with nontrivial steady states as well as a way to study their spectral properties and eigenmodes.