A probability density function generator based on neural networks

© 2019 Elsevier B.V. In order to generate a probability density function (PDF) for fitting the probability distributions of practical data, this study proposes a deep learning method which consists of two stages: (1) a training stage for estimating the cumulative distribution function (CDF) and (2) a performing stage for predicting the corresponding PDF. The CDFs of common probability distributions can be utilised as activation functions in the hidden layers of the proposed deep learning model for learning actual cumulative probabilities, and the differential equation of the trained deep learning model can be used to estimate the PDF. Numerical experiments with single and mixed distributions are conducted to evaluate the performance of the proposed method. The experimental results show that the values of both CDF and PDF can be precisely estimated by the proposed method

Dissociate lattice oxygen redox reactions from capacity and voltage drops of battery electrodes.

The oxygen redox (OR) activity is conventionally considered detrimental to the stability and kinetics of batteries. However, OR reactions are often confused by irreversible oxygen oxidation. Here, based on high-efficiency mapping of resonant inelastic x-ray scattering of both the transition metal and oxygen, we distinguish the lattice OR in Na0.6[Li0.2Mn0.8]O2 and compare it with Na2/3[Mg1/3Mn2/3]O2. Both systems display strong lattice OR activities but with distinct electrochemical stability. The comparison shows that the substantial capacity drop in Na0.6[Li0.2Mn0.8]O2 stems from non-lattice oxygen oxidations, and its voltage decay from an increasing Mn redox contribution upon cycling, contrasting those in Na2/3[Mg1/3Mn2/3]O2. We conclude that lattice OR is not the ringleader of the stability issue. Instead, irreversible oxygen oxidation and the changing cationic reactions lead to the capacity and voltage fade. We argue that lattice OR and other oxygen activities should/could be studied and treated separately to achieve viable OR-based electrodes

Age-related changes in the effects of strength training on lower leg muscles in healthy individuals measured using MRI

BACKGROUND: We previously measured the rate of regaining muscle strength during rehabilitation of lower leg muscles in patients following lower leg casting. Our primary aim in this study was to measure the rate of gain of strength in healthy individuals undergoing a similar training regime. Our secondary aim was to test the ability of MRI to provide a biomarker for muscle function. METHODS: Men and women were recruited in three age groups: 20-30, 50-65 and over 70 years. Their response to resistance training of the right lower leg twice a week for 8 weeks was monitored using a dynamometer and MRI of tibialis anterior, soleus and gastrocnemius muscles at 2 weekly intervals to measure muscle size (anatomical cross-sectional area (ACSA)) and quality (T2 relaxation). Forty-four volunteers completed the study. RESULTS: Baseline strength declined with age. Training had no effect in middle-aged females or in elderly men in dorsiflexion. Other groups significantly increased both plantarflexion and dorsiflexion strength at rates up to 5.5 N m week(-1) in young females in plantarflexion and 1.25 N m week(-1) in young males in dorsiflexion. No changes were observed in ACSA or T2 in any age group in any muscle. CONCLUSION: Exercise training improves muscle strength in males at all ages except the elderly in dorsiflexion. Responses in females were less clear with variation across age and muscle groups. These results were not reflected in simple MRI measures that do not, therefore, provide a good biomarker for muscle atrophy or the efficacy of rehabilitation

Direct Construction of Recursive MDS Diffusion Layers using Shortened BCH Codes

MDS matrices allow to build optimal linear diffusion layers in block ciphers. However, MDS matrices cannot be sparse and usually have a large description, inducing costly software/hardware implementations. Recursive MDS matrices allow to solve this problem by focusing on MDS matrices that can be computed as a power of a simple companion matrix, thus having a compact description suitable even for constrained environ- ments. However, up to now, finding recursive MDS matrices required to perform an exhaustive search on families of companion matrices, thus limiting the size of MDS matrices one could look for. In this article we propose a new direct construction based on shortened BCH codes, al- lowing to efficiently construct such matrices for whatever parameters. Unfortunately, not all recursive MDS matrices can be obtained from BCH codes, and our algorithm is not always guaranteed to find the best matrices for a given set of parameters.Comment: Best paper award; Carlos Cid and Christian Rechberger. 21st International Workshop on Fast Software Encryption, FSE 2014, Mar 2014, London, United Kingdom. springe

A longitudinal study of muscle rehabilitation in the lower leg after cast removal using magnetic resonance imaging and strength assessment

Magnetic resonance imaging (MRI) was used to investigate muscle rehabilitation following cast immobilization. The aim was to explore MRI as an imaging biomarker of muscle function. Sixteen patients completed an eight-week rehabilitation programme following six weeks of cast immobilization for an ankle fracture. MRI of the lower leg was performed at two-week intervals for 14 weeks. Total volume and anatomical cross-sectional areas at 70% of the distance from lateral malleolus to tibial tuberosity (ACSA) were measured for tibialis anterior (TA), medial and lateral gastrocnemius (GM and GL) and soleus (SOL). Pennation angle of muscle fascicules was measured at the same position in GM. Fractional fat/water contents and T2 relaxation times before and after exercise were calculated. Strength was measured as maximum isometric torque developed in plantar- and dorsi-flexion. Torque increased by (mean [SD]) 1.10 (0.32) N m day−1 in males, 0.74 (0.43) N m day−1 in females in plantar-flexion (0.9% of final strength per day), and 0.36 (0.15) N m day−1 in males, 0.28 (0.19) N m day−1 in females in dorsi-flexion (1.1% per day). Neither difference between males and females was significant. Volume and ACSA of muscles recovered by week 14 apart from SOL which was still 6.8% smaller (p = 0.006) than the contralateral leg. T2 peaked at the end of the cast period for TA and SOL, and at week 8 for GM before returning to baseline. Pennation angle recovered rapidly following cast removal. Quantitative MRI can generate markers of muscle biomechanics and indicates that many of these return to baseline within eight weeks of remobilization

Zebrafish (Danio rerio) as a possible bioindicator of epigenetic factors present in drinking water that may affect reproductive function: is chorion an issue?

[EN] Emerging organic contaminants have been monitored in stream waters, raw and finished waters and wastewater effluents. Most of these contaminants, such as epigenetic substances, have been detected at very low levels. Unfortunately, their complete monitoring and/or removal are very difficult, given the increasing presence of new contaminants and due to analytical and economic considerations. For this reason, bioindicators are used as an alternative to monitor their presence. To this end, zebrafish is being used to assess certain contaminants in water quality studies. As our long-term aim is to determine if zebrafish (Danio rerio) can be used to detect environmental epigenetic factors in drinking waters with effects on human reproduction, an initial question is whether the chorion could interfere with the possible action of epigenetic factors in two reproductive events: genital ridge formation and migration of the primordial germ cells (PGCs) to these genital ridges. In the first experiment, we attempted to partially degrade the chorion of mid blastula transition (MBT) embryos with pronase, with acceptable survival rates at 5 days post fertilisation (dpf), with the group exposed for 15 min giving the best survival results. As denuded early embryos require a specific culture medium, in the next experiment embryo survival was evaluated when they were cultured up to 5 dpf in drinking waters from six different sources. Results showed a negative effect on embryo survival at 5 dpf from several waters but not in others, thus distorting the survival outcomes. These results suggest using embryos with the chorion intact from the outset when drinking waters from different sources are to be tested.Martínez-Sales, MI.; García Ximenez, F.; Espinos Gutierrez, FJ. (2015). Zebrafish (Danio rerio) as a possible bioindicator of epigenetic factors present in drinking water that may affect reproductive function: is chorion an issue?. Zygote. 23(3):447-452. doi:10.1017/S0967199414000045S44745223

Metal-insulator transition in vanadium dioxide nanobeams: probing sub-domain properties of strongly correlated materials

Many strongly correlated electronic materials, including high-temperature superconductors, colossal magnetoresistance and metal-insulator-transition (MIT) materials, are inhomogeneous on a microscopic scale as a result of domain structure or compositional variations. An important potential advantage of nanoscale samples is that they exhibit the homogeneous properties, which can differ greatly from those of the bulk. We demonstrate this principle using vanadium dioxide, which has domain structure associated with its dramatic MIT at 68 degrees C. Our studies of single-domain vanadium dioxide nanobeams reveal new aspects of this famous MIT, including supercooling of the metallic phase by 50 degrees C; an activation energy in the insulating phase consistent with the optical gap; and a connection between the transition and the equilibrium carrier density in the insulating phase. Our devices also provide a nanomechanical method of determining the transition temperature, enable measurements on individual metal-insulator interphase walls, and allow general investigations of a phase transition in quasi-one-dimensional geometry.Comment: 9 pages, 3 figures, original submitted in June 200

Export of functional Streptomyces coelicolor alditol oxidase to the periplasm or cell surface of Escherichia coli and its application in whole-cell biocatalysis

Streptomyces coelicolor A3(2) alditol oxidase (AldO) is a soluble monomeric flavoprotein in which the flavin cofactor is covalently linked to the polypeptide chain. AldO displays high reactivity towards different polyols such as xylitol and sorbitol. These characteristics make AldO industrially relevant, but full biotechnological exploitation of this enzyme is at present restricted by laborious and costly purification steps. To eliminate the need for enzyme purification, this study describes a whole-cell AldO biocatalyst system. To this end, we have directed AldO to the periplasm or cell surface of Escherichia coli. For periplasmic export, AldO was fused to endogenous E. coli signal sequences known to direct their passenger proteins into the SecB, signal recognition particle (SRP), or Twin-arginine translocation (Tat) pathway. In addition, AldO was fused to an ice nucleation protein (INP)-based anchoring motif for surface display. The results show that Tat-exported AldO and INP-surface-displayed AldO are active. The Tat-based system was successfully employed in converting xylitol by whole cells, whereas the use of the INP-based system was most likely restricted by lipopolysaccharide LPS in wild-type cells. It is anticipated that these whole-cell systems will be a valuable tool for further biological and industrial exploitation of AldO and other cofactor-containing enzymes.

Comprehensive workplace intervention for cancer prevention in China (WECAN): protocol for a stepped-wedge, cluster-randomised controlled trial.

INTRODUCTION: Cancer is the second leading cause of death across the globe with the majority of deaths occurring in low-income and middle-income countries. Evidence has shown that the cancer burden can be substantially reduced by avoiding behavioural risk factors through comprehensive intervention strategies, including workplace health promotion, which has shown to be cost-effective in developed countries while rarely conducted in developing countries. This study aims to explore a feasible and sustainable approach to the prevention and control of cancer in China by developing an evidence-based comprehensive workplace health model equipped with a smartphone application for implementation. METHODS AND ANALYSIS: This study is designed as a stepped-wedge, cluster-randomised controlled trial. We will recruit 15 workplaces from three cities in China. A total of 750 employees will be randomly selected for evaluation that includes five rounds of survey conducted every 6 months. After the second evaluation, workplaces will be randomly allocated to start the intervention sequentially every 6 months in three steps with five workplaces per step. A mobile application 'Healthy Workplace' will be developed to support the intervention. On-line and off-line health-related activities will be carried out among employees. Employers will provide supportive policies, environment and benefits to facilitate the adoption of healthy behaviours. The primary outcome is the change of Healthy Lifestyle Index Score, which consists of five components including smoking, alcohol drinking, physical activity, diet and body mass index. ETHICS AND DISSEMINATION: The study has been approved by Queen Mary University of London Ethics of Research Committee (QMERC22.257) and Chinese Centre for Disease Control and Prevention Institutional Review Board (202210). Written informed consent is required from all participants. Results will be disseminated through presentations, publications and social media. TRIAL REGISTRATION NUMBER: ChiCTR2200058680

Resolution of complex fluorescence spectra of lipids and nicotinic acetylcholine receptor by multivariate analysis reveals protein-mediated effects on the receptor's immediate lipid microenvironment

Analysis of fluorescent spectra from complex biological systems containing various fluorescent probes with overlapping emission bands is a challenging task. Valuable information can be extracted from the full spectra, however, by using multivariate analysis (MA) of measurements at different wavelengths. We applied MA to spectral data of purified Torpedo nicotinic acetylcholine receptor (AChR) protein reconstituted into liposomes made up of dioleoylphosphatidic acid (DOPA) and dioleoylphosphatidylcholine (DOPC) doped with two extrinsic fluorescent probes (NBD-cholesterol/pyrene-PC). Förster resonance energy transfer (FRET) was observed between the protein and pyrene-PC and between pyrene-PC and NBD-cholesterol, leading to overlapping emission bands. Partial least squares analysis was applied to fluorescence spectra of pyrene-PC in liposomes with different DOPC/DOPA ratios, generating a model that was tested by an internal validation (leave-one-out cross-validation) and was further used to predict the apparent lipid molar ratio in AChR-containing samples. The values predicted for DOPA, the lipid with the highest Tm, indicate that the protein exerts a rigidifying effect on its lipid microenvironment. A similar conclusion was reached from excimer formation of pyrene-PC, a collisional-dependent phenomenon. The excimer/monomer ratio (E/M) at different DOPC/DOPA molar ratios revealed the restricted diffusion of the probe in AChR-containing samples in comparison to pure lipid samples devoid of protein. FRET from the AChR (donor) to pyrene-PC (acceptor) as a function of temperature was found to increase with increasing temperature, suggesting a shorter distance between AChR and pyrene PC. Taken together, the results obtained by MA on complex spectra indicate that the AChR rigidifies its surrounding lipid and prefers DOPA rather than DOPC in its immediate microenvironment