Blind estimation of MIMO relay channels

In this paper, we integrate two blind source separation (BSS) methods to estimate the individual channel state information (CSI) for the source-relay and relay-destination links of three-node two-hop multiple-input multiple-output (MIMO) relay systems. In particular, we propose a first-order Z-domain precoding technique for the blind estimation of the relay-destination channel matrix, while an algorithm based on the constant modulus and mutual information properties is developed to estimate the source-relay channel matrix. Compared with training-based MIMO relay channel estimation approaches, our algorithm has a better bandwidth efficiency as no bandwidth is wasted for sending the training sequences. Numerical examples are shown to demonstrate the performance of the proposed algorithm. © 2014 IEEE.

Image encryption based on compressed sensing and blind source separation

A novel image encryption scheme based on compressed sensing and blind source separation is proposed in this work, where there is no statistical requirement to plaintexts. In the proposed method, for encryption, the plaintexts and keys are mixed with each other using a underdetermined matrix first, and then compressed under a project matrix. As a result, it forms a difficult underdetermined blind source separation (UBSS) problem without statistical features of sources. Regarding the decryption, given the keys, a new model will be constructed, which is solvable under compressed sensing (CS) frame. Due to the usage of CS technology, the plaintexts are compressed into the data with smaller size when they are encrypted. Meanwhile, they can be decrypted from parts of the received data packets and thus allows to lose some packets. This is beneficial for the proposed encryption method to suit practical communication systems. Simulations are given to illustrate the availability and the superiority of our method.

Does data frequency matter for the impact of forward premium on spot exchange rate?

In this paper we take the forward premium and exchange rate literature forward by asking whether data frequency matters in that relationship. We use four frequencies of data, namely, quarterly, monthly, weekly and daily. We find that data frequencies matter both statistically and economically. More specifically, we document that investors prefer the forward premium model over a constant returns model in most countries when models are estimated using daily, weekly, and quarterly data, but not when using monthly data.

Fructose-1, 6-diphosphate (FDP) as a novel antidote for yellow oleander-induced cardiac toxicity: a randomized controlled double blind study

BACKGROUND: Cardiac toxicity due to ingestion of oleander plant seeds in Sri Lanka and some other South Asian countries is very common. At present symptomatic oleander seed poisoning carries a mortality of 10% in Sri Lanka and treatment of yellow oleander poisoning is limited to gastric decontamination and atropine administration. The only proven effective antidote is digoxin antibodies but these are not available for routine use because of the high cost. The main objective of this study is to investigate the effectiveness of a new and inexpensive antidote for patients with life threatening arrhythmias due oleander poisoning. METHOD/DESIGN: We set up a randomised double blind clinical trial to assess the effectiveness of Fructose 1, 6 diphosphate (FDP) in acute yellow oleander poisoning patients admitted to the adult medical wards of a tertiary hospital in Sri Lanka. Patients will be initially resuscitated following the national guidelines and eligible patients will be randomised to receive either FDP or an equal amount of normal saline. The primary outcome measure for this study is the sustained reversion to sinus rhythm with a heart rate greater than 50/min within 2 hours of completion of FDP/placebo bolus. Secondary outcomes include death, reversal of hyperkalaemia on the 6, 12, 18 and 24 hour samples and maintenance of sinus rhythm on the holter monitor. Analysis will be on intention-to-treat. DISCUSSION: This trial will provide information on the effectiveness of FDP in yellow oleander poisoning. If FDP is effective in cardiac glycoside toxicity, it would provide substantial benefit to the patients in rural Asia. The drug is inexpensive and thus could be made available at primary care hospitals if proven to be effective. TRIAL REGISTRATION: Current Controlled trial ISRCTN71018309.

Web-based alcohol intervention for Māori university students: double-blind, multi-site randomized controlled trial

AIMS: Like many indigenous peoples, New Zealand Māori bear a heavy burden of alcohol-related harm relative to their non-indigenous compatriots, and disparities are greatest among young adults. We tested the effectiveness of web-based alcohol screening and brief intervention (e-SBI) for reducing hazardous drinking among Māori university students. DESIGN: Parallel, double-blind, multi-site, randomized controlled trial. SETTING: Seven of New Zealand's eight universities. PARTICIPANTS: In April 2010, we sent e-mail invitations to all 6697 17-24-year-old Māori students to complete a brief web questionnaire including the Alcohol Use Disorders Identification Test (AUDIT)-C, a screening tool for hazardous and harmful drinking. Those screening positive were computer randomized to: <10 minutes of web-based alcohol assessment and personalized feedback (intervention) or screening alone (control). MEASUREMENTS: We conducted a fully automated 5-month follow-up assessment with observers and participants blinded to study hypotheses, design and intervention delivery. Pre-determined primary outcomes were: (i) frequency of drinking, (ii) amount consumed per typical drinking occasion, (iii) overall volume of alcohol consumed and (iv) academic problems. FINDINGS: Of the participants, 1789 were hazardous or harmful drinkers (AUDIT-C ≥ 4) and were randomized: 850 to control, 939 to intervention. Follow-up assessments were completed by 682 controls (80%) and 733 intervention group members (78%). Relative to controls, participants receiving intervention drank less often [RR = 0.89; 95% confidence interval (CI): 0.82-0.97], less per drinking occasion (RR = 0.92; 95% CI: 0.84-1.00), less overall (RR = 0.78; 95% CI: 0.69-0.89) and had fewer academic problems (RR = 0.81; 95% CI: 0.69-0.95). CONCLUSIONS: Web-based screening and brief intervention reduced hazardous and harmful drinking among non-help-seeking Māori students in a large-scale pragmatic trial. The study has wider implications for behavioural intervention in the important but neglected area of indigenous health.

N-Acetyl Cysteine (NAC) in the treatment of obsessive-compulsive disorder: a 16-week, double-blind, randomised, placebo-controlled study

BACKGROUND: Obsessive-compulsive disorder (OCD) is a disabling mental illness for which pharmacological and psychosocial interventions are all too often inadequate. Recent preclinical and clinical studies have implicated dysfunction of glutamatergic neurotransmission in the pathophysiology of OCD. The amino acid-based nutraceutical N-acetyl cysteine (NAC) is a safe and readily available agent that has been found to modify the synaptic release of glutamate in subcortical brain regions via modulation of the cysteine-glutamate antiporter. OBJECTIVE: The aim of this study was to assess the efficacy and safety of NAC in treating OCD. METHODS: A 16-week, double-blind, placebo-controlled, randomised trial using 3 g/day of NAC (1.5 g twice daily) in 44 participants (aged 18-70 years) with Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5)-diagnosed OCD, during 2013-2015. The primary outcome measure was the Yale-Brown Obsessive Compulsive Scale (YBOCS), conducted every 4 weeks. RESULTS: Analysis of the full sample (intention-to-treat) with repeated measures mixed linear modelling revealed a nonsignificant time × treatment interaction for the YBOCS scale total score (p = 0.39). A per-protocol analysis removing protocol violators also failed to show a significant time × treatment interaction for YBOCS total score (p = 0.15). However, a significant time × treatment interaction was observed for the YBOCS 'Compulsions' subscale in favour of NAC (p = 0.013), with a significant reduction observed at week 12 (dissipating at week 16). At 16 weeks, only four (20 %) participants were considered 'responders' (YBOCS ≥35 % reduction at endpoint) versus four (27 %) in the placebo group. The NAC was well-tolerated, aside from more cases of heartburn occurring compared with placebo (p = 0.045). CONCLUSION: Further research involving NAC for OCD may require larger samples to detect moderate or small effect sizes, involve dosage or formulation differences, use in concert with exposure therapy, or an additional post-study observational period to mitigate study withdrawal. TRIAL REGISTRATION: ACTRN12613000310763.

A single-blind, randomised controlled trial on the effects of lithium and quetiapine monotherapy on the trajectory of cognitive functioning in first episode mania: A 12-month follow-up study

BACKGROUND: Cognitive deficits have been reported during the early stages of bipolar disorder; however, the role of medication on such deficits remains unclear. The aim of this study was to compare the effects of lithium and quetiapine monotherapy on cognitive performance in people following first episode mania. METHODS: The design was a single-blind, randomised controlled trial on a cohort of 61 participants following first episode mania. Participants received either lithium or quetiapine monotherapy as maintenance treatment over a 12-month follow-up period. The groups were compared on performance outcomes using an extensive cognitive assessment battery conducted at baseline, month 3 and month 12 follow-up time-points. RESULTS: There was a significant interaction between group and time in phonemic fluency at the 3-month and 12-month endpoints, reflecting greater improvements in performance in lithium-treated participants relative to quetiapine-treated participants. After controlling for multiple comparisons, there were no other significant interactions between group and time for other measures of cognition. CONCLUSION: Although the effects of lithium and quetiapine treatment were similar for most cognitive domains, the findings imply that early initiation of lithium treatment may benefit the trajectory of cognition, specifically verbal fluency in young people with bipolar disorder. Given that cognition is a major symptomatic domain of bipolar disorder and has substantive effects on general functioning, the ability to influence the trajectory of cognitive change is of considerable clinical importance.

A convex geometry-based blind source separation method for separating nonnegative sources

This paper presents a convex geometry (CG)-based method for blind separation of nonnegative sources. First, the unaccessible source matrix is normalized to be column-sum-to-one by mapping the available observation matrix. Then, its zero-samples are found by searching the facets of the convex hull spanned by the mapped observations. Considering these zero-samples, a quadratic cost function with respect to each row of the unmixing matrix, together with a linear constraint in relation to the involved variables, is proposed. Upon which, an algorithm is presented to estimate the unmixing matrix by solving a classical convex optimization problem. Unlike the traditional blind source separation (BSS) methods, the CG-based method does not require the independence assumption, nor the uncorrelation assumption. Compared with the BSS methods that are specifically designed to distinguish between nonnegative sources, the proposed method requires a weaker sparsity condition. Provided simulation results illustrate the performance of our method.