Informed baseline subtraction of proteomic mass spectrometry data aided by a novel sliding window algorithm

Proteomic matrix-assisted laser desorption/ionisation (MALDI) linear time-of-flight (TOF) mass spectrometry (MS) may be used to produce protein profiles from biological samples with the aim of discovering biomarkers for disease. However, the raw protein profiles suffer from several sources of bias or systematic variation which need to be removed via pre-processing before meaningful downstream analysis of the data can be undertaken. Baseline subtraction, an early pre-processing step that removes the non-peptide signal from the spectra, is complicated by the following: (i) each spectrum has, on average, wider peaks for peptides with higher mass-to-charge ratios (m/z), and (ii) the time-consuming and error-prone trial-and-error process for optimising the baseline subtraction input arguments. With reference to the aforementioned complications, we present an automated pipeline that includes (i) a novel `continuous' line segment algorithm that efficiently operates over data with a transformed m/z-axis to remove the relationship between peptide mass and peak width, and (ii) an input-free algorithm to estimate peak widths on the transformed m/z scale. The automated baseline subtraction method was deployed on six publicly available proteomic MS datasets using six different m/z-axis transformations. Optimality of the automated baseline subtraction pipeline was assessed quantitatively using the mean absolute scaled error (MASE) when compared to a gold-standard baseline subtracted signal. Near-optimal baseline subtraction was achieved using the automated pipeline. The advantages of the proposed pipeline include informed and data specific input arguments for baseline subtraction methods, the avoidance of time-intensive and subjective piecewise baseline subtraction, and the ability to automate baseline subtraction completely. Moreover, individual steps can be adopted as stand-alone routines.Comment: 50 pages, 19 figure

Behaviour of modified insulator surface material under electric stress

Performance of electrical insulators is strongly dependent on their surface properties. In practice manufactures and utilities are using different means to improve them. New materials the insulators or coatings have been used in electric power systems. Also new technologies are tested to modifL insulators glaze, mainly plasma processes. During these processes some changes in the constitution of glaze has to be done and then a new hydrophobic layer is created. Some electrical and physical properties of modified (silicon rubber and fluorourethane coatings, plasma technology) and non-modified real insulators glaze have been presented. These investigations have shown that plasma processes are able to improve the surface properties of the glaze. Since the electrohydrodynamic behaviour of water droplets on the outdoor electrical insulation surface is very important, observations have been done by using a high-speed photo camera

Effects of Surface Modification of Polypropylene Foil on Polymer - Oil Interaction

Physico-chemical interactions between the impregnating oil and the polypropylene foil (PP) are of great concern. Such phenomena like swelling and dissolution of polymer films into the oil can detonate the electrical properties of the oil - polymer system. It was found that the swelling control could be attained by the application of the effective diffusion barrier at the PP surface. Formation of thin polymer coatings in radio-frequency discharges was used for this purpose. The effect of surface modification of the PP film on the polymer-oil interaction phenomena were investigated

Arene oxidation with malonoyl peroxides

Malonoyl peroxide 7, prepared in a single step from the commercially available diacid, is an effective reagent for the oxidation of aromatics. Reaction of an arene with peroxide 7 at room temperature leads to the corresponding protected phenol which can be unmasked by aminolysis. An ionic mechanism consistent with the experimental findings and supported by isotopic labeling, Hammett analysis, EPR investigations and reactivity profile studies is proposed

Cross-sectional analysis of association between socioeconomic status and utilization of primary total hip joint replacements 2006-7 : Australian orthopaedic association national joint replacement registry

Background The utilization of total hip replacement (THR) surgery is rapidly increasing, however few data examine whether these procedures are associated with socioeconomic status (SES) within Australia. This study examined primary THR across SES for both genders for the Barwon Statistical Division (BSD) of Victoria, Australia.Methods Using the Australian Orthopaedic Association National Joint Replacement Registry data for 2006&ndash;7, primary THR with a diagnosis of osteoarthritis (OA) among residents of the BSD was ascertained. The Index of Relative Socioeconomic Disadvantage was used to measure SES; determined by matching residential addresses with Australian Bureau of Statistics census data. The data were categorised into quintiles; quintile 1 indicating the most disadvantaged. Age- and sex-specific rates of primary THR per 1,000 person years were reported for 10-year age bands using the total population at risk.Results Females accounted for 46.9% of the 642 primary THR performed during 2006&ndash;7. THR utilization per 1,000 person years was 1.9 for males and 1.5 for females. The highest utilization of primary THR was observed in those aged 70&ndash;79&thinsp;years (males 6.1, and females 5.4 per 1,000 person years). Overall, the U-shaped pattern of THR across SES gave the appearance of bimodality for both males and females, whereby rates were greater for both the most disadvantaged and least disadvantaged groups.Conclusions Further work on a larger scale is required to determine whether relationships between SES and THR utilization for the diagnosis of OA is attributable to lifestyle factors related to SES, or alternatively reflects geographic and health system biases. Identifying contributing factors associated with SES may enhance resource planning and enable more effective and focussed preventive strategies for hip OA. <br /

Mathematical model of high resistance standard performed in switched capacitor technology

W pracy zaprezentowano model matematyczny 6-cio elementowego wzorca dużych rezystancji (zrealizowanego w technice przełączalnych pojemności SC) przeznaczonego do sprawdzania wskazań wybranych mierników do pomiarów dużych rezystancji, np. megaomomierzy. Zaletą prezentowanej idei budowy wzorca dużych rezystancji jest możliwość zmiany nastawy odtwarzanej wartości rezystancji za pomocą parametrów (częstotliwości, współczynnika wypełnienia) sygnału sterującego procesem przełączania kondensatora.The paper presents the mathematical model of 6 - element high resistance standard (performed in Switched Capacitor technology) used for indications checking of chosen meters intended for high resistance measurements, eg. megaohmmeters. The advantage of presented high resistance standard construction idea is the possibility of realized resistance value changes by means of signal parameters (frequency, pulse width coefficient) controlling the switching process of a capacitor

Behaviour of modified insulator surface material under electric stress

Performance of electrical insulators is strongly dependent on their surface properties. In practice manufactures and utilities are using different means to improve them. New materials the insulators or coatings have been used in electric power systems. Also new technologies are tested to modifL insulators glaze, mainly plasma processes. During these processes some changes in the constitution of glaze has to be done and then a new hydrophobic layer is created. Some electrical and physical properties of modified (silicon rubber and fluorourethane coatings, plasma technology) and non-modified real insulators glaze have been presented. These investigations have shown that plasma processes are able to improve the surface properties of the glaze. Since the electrohydrodynamic behaviour of water droplets on the outdoor electrical insulation surface is very important, observations have been done by using a high-speed photo camera

Voltage Endurance Test of Vacuum Insulation for Cryocables

Vacuum insulation with cylindrical ceramic spacer insulators has been studied with respect to changes of its ac flashover voltage with time. The distributions of times to failure, which were found to confirm Weibull's distribution, were used for plotting the regression curves for times up to 350 h. The results show that even at rather low stresses the flashover voltage decreased in time. This phenomenon is connected with the recorded deposition of metal particles from the electrodes on the surface of the spacers during the tests. This possibility of the decrease of the flashover voltage, induced by the deconditioning effects of contaminating conducting particles generated under the working stress by the system itself, must be taken into account when considering the suitableness of using special means of increasing the short-time flashover voltage of vacuum insulation for cryocables