A combined method to estimate parameters of the thalamocortical model from a heavily noise-corrupted time series of action potential.

A combined method composing of the unscented Kalman filter (UKF) and the synchronization-based method is proposed for estimating electrophysiological variables and parameters of a thalamocortical (TC) neuron model, which is commonly used for studying Parkinson's disease for its relay role of connecting the basal ganglia and the cortex. In this work, we take into account the condition when only the time series of action potential with heavy noise are available. Numerical results demonstrate that not only this method can estimate model parameters from the extracted time series of action potential successfully but also the effect of its estimation is much better than the only use of the UKF or synchronization-based method, with a higher accuracy and a better robustness against noise, especially under the severe noise conditions. Considering the rather important role of TC neuron in the normal and pathological brain functions, the exploration of the method to estimate the critical parameters could have important implications for the study of its nonlinear dynamics and further treatment of Parkinson's disease.

Chaotic phase synchronization in small-world networks of bursting neurons.

We investigate the chaotic phase synchronization in a system of coupled bursting neurons in small-world networks. A transition to mutual phase synchronization takes place on the bursting time scale of coupled oscillators, while on the spiking time scale, they behave asynchronously. It is shown that phase synchronization is largely facilitated by a large fraction of shortcuts, but saturates when it exceeds a critical value. We also study the external chaotic phase synchronization of bursting oscillators in the small-world network by a periodic driving signal applied to a single neuron. It is demonstrated that there exists an optimal small-world topology, resulting in the largest peak value of frequency locking interval in the parameter plane, where bursting synchronization is maintained, even with the external driving. The width of this interval increases with the driving amplitude, but decrease rapidly with the network size. We infer that the externally applied driving parameters outside the frequency locking region can effectively suppress pathologically synchronized rhythms of bursting neurons in the brain.

The role of germline AIP, MEN1, PRKAR1A, CDKN1B and CDKN2C mutations in causing pituitary adenomas in a large cohort of children, adolescents, and patients with genetic syndromes.

The prevalence of germline mutations in MEN1, AIP, PRKAR1A, CDKN1B and CDKN2CI is unknown among pediatric patients with pituitary adenomas (PA). In this study, we screened children with PA for mutations in these genes; somatic GNAS mutations were also studied in a limited number of growth hormone (GH) or prolactin (PRL)-secreting PA. We studied 74 and 6 patients with either isolated Cushing disease (CD) or GH- or PRL-secreting PA, respectively. We also screened four pediatric patients with CD, and four with GH/PRL-secreting tumors who had some syndromic features. There was one AIP mutation (p.Lys103Arg) among 74 CD patients. Two MEN1 mutations that occurred in patients with recurrent or difficult-to-treat disease were found among patients with CD. There was one MEN1 and three AIP mutations (p.Gln307ProfsX104, p.Pro114fsX, p.Lys241X) among pediatric patients with isolated GH- or PRL-secreting PA and one additional MEN1 mutation in a patient with positive family history. There were no mutations in the PRKAR1A, CDKN1B, CDKN2C or GNAS genes. Thus, germline AIP or MEN1 gene mutations are frequent among pediatric patients with GH- or PRL-secreting PA but are significantly rarer in pediatric CD; PRKAR1A mutations are not present in PA outside of Carney complex.

Vibrational resonance in neuron populations.

In this paper different topologies of populations of FitzHugh-Nagumo neurons have been introduce to investigate the effect of high-frequency driving on the response of neuron populations to a subthreshold low-frequency signal. We show that optimal amplitude of high-frequency driving enhances the response of neuron populations to a subthreshold low-frequency input and the optimal amplitude dependences on the connection among the neurons. By analyzing several kinds of topology (i.e., random and small world) different behaviors have been observed. Several topologies behave in an optimal way with respect to the range of low-frequency amplitude leading to an improvement in the stimulus response coherence, while others with respect to the maximum values of the performance index. However, the best results in terms of both the suitable amplitude of high-frequency driving and high stimulus response coherence have been obtained when the neurons have been connected in a small-world topology.

Harmonics and intermodulation in subthreshold FitzHugh-Nagumo neuron.

Intermodulation and harmonics are important in frequency analysis of nonlinear systems. In neuron research, most investigations are taken in studying synchronization between the external stimuli and the output of neuron, but harmonics and intermodulation are often ignored. In this paper, harmonics and intermodulation of the subthreshold FitzHugh-Nagumo neuron are investigated and their magnitudes are used to predict frequency response of the neuron. Furthermore, through analyzing the magnitudes of harmonics, the intrinsic frequencies of the neuron could be identified.

How people from Chinese backgrounds make sense of and respond to the experiences of mental distress: Thematic analysis.

RATIONALE FOR THE STUDY: Many Chinese people do not contact mental health services when they first develop mental health problems. It is therefore important to find out reasons for low uptake of services so that strategies can be identified to promote early intervention. WHAT IS ALREADY KNOWN ABOUT THE TOPIC?: Most Chinese people only come into contact with mental health services during crisis situations. Language difference, lack of knowledge of mainstream services and stigma attached to mental health problems are barriers to access and utilize mental health services. WHAT THE STUDY ADDS TO THE INTERNATIONAL EVIDENCE?: Chinese people apply both Western medication and traditional healing to manage distress caused by mental health problems. Because of the extreme stigma associated with mental health problems, Chinese people are reluctant to accept support from their own cultural groups outside their family. Family plays a major role in caring for relatives with mental health problems. Families are prepared to travel across the world in search of folk healing if not available in Western societies. WHAT ARE THE IMPLICATIONS FOR PRACTICE?: It is important to recognize the different approaches to understanding and managing mental health problems among Chinese people, otherwise they will be dissuaded from engaging with mental health services if their beliefs are disregarded and invalidated. Services that involve Chinese speaking mental health workers can address the issue of language differences and sensitive mental health issues within the Chinese community. ABSTRACT: Introduction Late presentation and low utilization of mental health services are common among Chinese populations. An understanding of their journey towards mental health care helps to identify timely and appropriate intervention. Aim We aimed to examine how Chinese populations make sense of the experiences of mental distress, and how this understanding influences their pathways to mental health care. Method We undertook in-depth interviews with fourteen people with mental health problems (MHPs) and sixteen family members. Thematic analysis was used to analyse data. Results/Discussions Different conceptualization of mental distress and the stigma attached to MHPs explained why most participants accessed services at crisis points. Because of mental illness stigma, they were reluctant to seek help outside of the family. Participants used a pragmatic pluralistic approach to incorporate ritual healing and Western interventions to manage mental distress as they travelled further on the pathway journey. Families play a key role in the journey and are prepared to visit different parts of the world to seek traditional healers. Implications for practice Mental health nurses need to adopt a transcultural working approach to address mental health issues so that family will get the support needed to continue their caring role.

Second-order sliding mode controllers for nonlinear singular perturbation systems.

Nonlinear systems are decomposed into slow and fast response subsystems using the singular perturbation theory and second-order sliding mode controllers are designed for each of the subsystems. The combined control action forms a suboptimal controller that can eliminate chattering in the continuous control output. Simulated examples are included to demonstrate the effectiveness of the proposed algorithm.

Sensor data validation using gray models.

A new method based on the gray model is described for the online validation of measurements. A gray model is a differential equation describing the behavior of an accumulate generating operation (AGO) data sequence. First-order gray models are fitted to measuring data records using the recursive orthogonal least-squares algorithm. Predictions derived from the fitted gray model are then compared with the actual measurements to generate a prediction error sequence. The quality of the measured value is determined by the prediction errors and variance of the prediction error sequence. Experimental results for detecting the quality of measurements from a thermistor are presented.

Autotuning positive feedback time delay controller for dead time processes.

Biased relay feedback tests are applied to dead time processes to obtain their ultimate gains and ultimate frequencies. First-order process with dead time models are then fitted to the estimated gains and frequencies. A time delay controller that incorporates a simple compensator with a delay element in positive feedback can be derived from the fitted model. The time delay controller gives better performance comparing with classical Ziegler and Nichols tuned PID controller. Experimental study is included to demonstrate the effectiveness of the proposed tuning scheme and the time delay control algorithm.

Antiproliferative activity of the extract of Gleditsia sinensis fruit on human solid tumour cell lines.

BACKGROUND: The fruit extract of Gleditsia sinensis Lam. (GSE) is a traditional herbal medicine that is saponin-rich. However, its activity on solid tumour cell lines has never been demonstrated. METHODS: The activity of GSE was demonstrated in four cancer cell lines (breast cancer MCF-7, MDA-MB231, hepatoblastoma HepG2 and oesophageal squamous carcinoma cell line SLMT-1) using MTT assay, anchorage-independent clonogenicity assay, DNA laddering and in situ cell death detection. RESULTS: The mean MTT(50) (the mean concentration of GSE to reduce MTT activity by 50%) ranged from 16 to 20 microg/ml of GSE. An anchorage-independent clonogenicity assay showed that all of the four solid tumour cell lines gradually lost their regeneration potential after treatment with GSE, DNA fragmentation and TUNEL analysis demonstrated that the action of GSE is both dose- and time course-dependent. CONCLUSIONS: Our results suggest that GSE has a cytotoxic activity and can induce apoptosis in human solid tumour cell lines.