The Coincidence Problem in Holographic f(R) Gravity

It is well-known that $f(R)$ gravity models formulated in Einstein conformal frame are equivalent to Einstein gravity together with a minimally coupled scalar field. In this case, the scalar field couples with the matter sector and the coupling term is given by the conformal factor. We apply the holographic principle to such interacting models. In a spatially flat universe, we show that the Einstein frame representation of $f(R)$ models leads to a constant ratio of energy densities of dark matter to dark energy.Comment: 10 pages, no figure

Correlation of caveolin-1 expression with microlymphatic vessel density in colorectal adenocarcinoma tissues and its correlation with prognosis

AbstractObjectiveTo study the expression of caveolin-1 in colorectal adenocarcinoma tissues and its correlation with microlymphatic vessel density (LMVD), and to investigate the clinical pathological prognostic significance of caveolin-1 and LMVD in patients with colorectal cancer.MethodsThe expression of caveolin-1 and LMVD in 45 specimens of normal colorectal tissues, and 90 specimens of colorectal adenocarcinoma tissues were detected by immunohistochemistry technique. The correlation between their expression and the clinicopathologic features was analyzed. Multivariable Cox regression was used to analyze the association between the laboratory indices and overall survival time.ResultsThe positive rates of caveolin-1 in colorectal adenocarcinoma tissues were significantly higher than those in normal colorectal tissues (P < 0.01). LMVD in colorectal adenocarcinoma tissues were significantly higher than those in normal colorectal tissues (P < 0.01). Mean LMVD in group with caveolin-1 positive was significantly higher than in that with caveolin-1 negative. The median survival time was 26.7 months. Cox regression analysis showed that the caveolin-1 expression, invation depth, lymph node metastasis, TNM stage, liver metastasis and LMVD were independent risk factors of overall survival time of patients with colorectal carcinoma.ConclusionsCaveolin-1 may contribute to the lymphangiogenesis in the tumor. During the occurrence and development of colorectal adenocarcinoma, there is a close relationship between the expression of caveolin-1 and lymphatic microvessel of tumor. Caveolin-1 expression and microlymphatic vessel density are significant prognostic value of colorectal carcinoma

Developments in the fluidised bed process for fibre recovery from thermoset composites

Carbon fibre reinforced plastic (CFRP) is being used in increasing quantities particularly in the transport industry to reduce carbon emissions through weight reduction and in the energy industries for renewable technologies, such as wind turbines. As a high value and energy intensive material to manufacture a good case can be made for recovering and reusing carbon fibre from waste material. A number of companies in Europe and the USA are now in the early stages of commercial operation, but the focus is upon the recycling of clean, uncontaminated scrap from manufacturing processes and it is recognised that CFRP that is mixed with other materials eg. sandwich panels, metal inserts, painted surfaces and composites made from toughened polymers are more difficult to recycle effectively with existing commercial processes. The fluidised bed process developed at the University of Nottingham for recovering carbon fibre from waste composite material has the potential to process mixed and contaminated CFRP waste. The oxidising conditions allow full removal of any organic materials and the fluidised bed effectively separates the carbon fibres from other incombustible materials, such as metals. The process has now been developed to a scale representative of commercial operation and a waste CFRP comprising intermediate modulus carbon fibre and toughened epoxy resin has been processed successfully and good quality recycled fibres recovered. This paper will present the results and discuss the quality of the carbon fibre recovered from the process. A discussion of some of the key requirements to build a viable fluidised bed plant will also be presented

BCI-FES training system design and implementation for rehabilitation of stroke patients

Author name used in this publication: Kai-yu TongAuthor name used in this publication: Suk-tak ChanRefereed conference paper2007-2008 > Academic research: refereed > Refereed conference paperVersion of RecordPublishe

Cerebral plasticity after subcortical stroke as revealed by cortico-muscular coherence

Author name used in this publication: Kai-Yu TongAuthor name used in this publication: Suk-Tak Chan2008-2009 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Environmental aspects of use of recycled carbon fibre composites in automotive applications

The high cost and energy intensity of virgin carbon fibre manufacture provides an opportunity to recover substantial value from carbon fibre reinforced plastic wastes. In this study, we assess the life cycle environmental implications of recovering carbon fibre and producing composite materials as substitutes for conventional and proposed lightweight materials in automotive applications (e.g., steel, aluminium, virgin carbon fibre). Key parameters for the recycled carbon fibre materials, including fibre volume fraction and fibre alignment, are investigated to identify beneficial uses of recycled carbon fibre in the automotive sector. Recycled carbon fibre components can achieve the lowest life cycle environmental impacts of all materials considered, although the actual impact is highly dependent on the design criteria (λ value) of the specific component. Low production impacts associated with recycled carbon fibre components are observed relative to lightweight competitor materials (e.g., aluminium, virgin carbon fibre reinforced plastic). In addition, recycled carbon fibre components have low in-use energy use due to mass reductions and associated reduction in mass-induced fuel consumption. The results demonstrate environmental feasibility of the CFRP recycling materials, supporting the emerging commercialisation of CF recycling technologies and identifying significant potential market opportunities in the automotive sector

Applications of Direct Injection Soft Chemical Ionisation-Mass Spectrometry for the Detection of Pre-blast Smokeless Powder Organic Additives

Analysis of smokeless powders is of interest from forensics and security perspectives. This article reports the detection of smokeless powder organic additives (in their pre-detonation condition), namely the stabiliser diphenylamine and its derivatives 2-nitrodiphenylamine and 4-nitrodiphenylamine, and the additives (used both as stabilisers and plasticisers) methyl centralite and ethyl centralite, by means of swab sampling followed by thermal desorption and direct injection soft chemical ionisation-mass spectrometry. Investigations on the product ions resulting from the reactions of the reagent ions H3O+ and O2+ with additives as a function of reduced electric field are reported. The method was comprehensively evaluated in terms of linearity, sensitivity and precision. For H3O+, the limits of detection (LoD) are in the range of 41-88 pg of additive, for which the accuracy varied between 1.5 and 3.2%, precision varied between 3.7 and 7.3% and linearity showed R20.9991. For O2+, LoD are in the range of 72 to 1.4 ng, with an accuracy of between 2.8 and 4.9% and a precision between 4.5 and 8.6% and R20.9914. The validated methodology was applied to the analysis of commercial pre-blast gun powders from different manufacturers.(VLID)4826148Accepted versio

Comparison of techniques for handling missing covariate data within prognostic modelling studies: a simulation study

Background: There is no consensus on the most appropriate approach to handle missing covariate data within prognostic modelling studies. Therefore a simulation study was performed to assess the effects of different missing data techniques on the performance of a prognostic model. Methods: Datasets were generated to resemble the skewed distributions seen in a motivating breast cancer example. Multivariate missing data were imposed on four covariates using four different mechanisms; missing completely at random (MCAR), missing at random (MAR), missing not at random (MNAR) and a combination of all three mechanisms. Five amounts of incomplete cases from 5% to 75% were considered. Complete case analysis (CC), single imputation (SI) and five multiple imputation (MI) techniques available within the R statistical software were investigated: a) data augmentation (DA) approach assuming a multivariate normal distribution, b) DA assuming a general location model, c) regression switching imputation, d) regression switching with predictive mean matching (MICE-PMM) and e) flexible additive imputation models. A Cox proportional hazards model was fitted and appropriate estimates for the regression coefficients and model performance measures were obtained. Results: Performing a CC analysis produced unbiased regression estimates, but inflated standard errors, which affected the significance of the covariates in the model with 25% or more missingness. Using SI, underestimated the variability; resulting in poor coverage even with 10% missingness. Of the MI approaches, applying MICE-PMM produced, in general, the least biased estimates and better coverage for the incomplete covariates and better model performance for all mechanisms. However, this MI approach still produced biased regression coefficient estimates for the incomplete skewed continuous covariates when 50% or more cases had missing data imposed with a MCAR, MAR or combined mechanism. When the missingness depended on the incomplete covariates, i.e. MNAR, estimates were biased with more than 10% incomplete cases for all MI approaches. Conclusion: The results from this simulation study suggest that performing MICE-PMM may be the preferred MI approach provided that less than 50% of the cases have missing data and the missing data are not MNAR

Combining estimates of interest in prognostic modelling studies after multiple imputation: current practice and guidelines

Background: Multiple imputation (MI) provides an effective approach to handle missing covariate data within prognostic modelling studies, as it can properly account for the missing data uncertainty. The multiply imputed datasets are each analysed using standard prognostic modelling techniques to obtain the estimates of interest. The estimates from each imputed dataset are then combined into one overall estimate and variance, incorporating both the within and between imputation variability. Rubin's rules for combining these multiply imputed estimates are based on asymptotic theory. The resulting combined estimates may be more accurate if the posterior distribution of the population parameter of interest is better approximated by the normal distribution. However, the normality assumption may not be appropriate for all the parameters of interest when analysing prognostic modelling studies, such as predicted survival probabilities and model performance measures. Methods: Guidelines for combining the estimates of interest when analysing prognostic modelling studies are provided. A literature review is performed to identify current practice for combining such estimates in prognostic modelling studies. Results: Methods for combining all reported estimates after MI were not well reported in the current literature. Rubin's rules without applying any transformations were the standard approach used, when any method was stated. Conclusion: The proposed simple guidelines for combining estimates after MI may lead to a wider and more appropriate use of MI in future prognostic modelling studies

Two-dimensional nanosecond electric field mapping based on cell electropermeabilization

Nanosecond, megavolt-per-meter electric pulses cause permeabilization of cells to small molecules, programmed cell death (apoptosis) in tumor cells, and are under evaluation as a treatment for skin cancer. We use nanoelectroporation and fluorescence imaging to construct two-dimensional maps of the electric field associated with delivery of 15 ns, 10 kV pulses to monolayers of the human prostate cancer cell line PC3 from three different electrode configurations: single-needle, five-needle, and flat-cut coaxial cable. Influx of the normally impermeant fluorescent dye YO-PRO-1 serves as a sensitive indicator of membrane permeabilization. The level of fluorescence emission after pulse exposure is proportional to the applied electric field strength. Spatial electric field distributions were compared in a plane normal to the center axis and 15-20 μm from the tip of the center electrode. Measurement results agree well with models for the three electrode arrangements evaluated in this study. This live-cell method for measuring a nanosecond pulsed electric field distribution provides an operationally meaningful calibration of electrode designs for biological applications and permits visualization of the relative sensitivities of different cell types to nanoelectropulse stimulation. PACS Codes: 87.85.M