Optimized time alignment algorithm for LC-MS data: correlation optimized warping using component detection algorithm-selected mass chromatograms

Correlation optimized warping (COW) based on the total ion current (TIC) is a widely used time alignment algorithm (COW-TIC). This approach works successfully on chromatograms containing few compounds and having a well-defined TIC. In this paper, we have combined COW with a component detection algorithm (CODA) to align LC-MS chromatograms containing thousands of biological compounds with overlapping chromatographic peaks, a situation where COW-TIC often fails. CODA is a variable selection procedure that selects mass chromatograms with low noise and low background (so-called "high-quality" mass chromatograms). High-quality mass chromatograms selected in each COW segment ensure that the same compounds (based on their mass and their retention time) are used in the two-dimensional benefit function of COW to obtain correct and optimal alignments (COW-CODA). The performance of the COW-CODA algorithm was evaluated on three types of complex data sets obtained from the LC-MS analysis of samples commonly used for biomarker discovery and compared to COW-TIC using a new global comparison method based on overlapping peak area: trypsin-digested serum obtained from cervical cancer patients, trypsin-digested serum from a single patient that was treated with varying preanalytical parameters (factorial design study), and urine from pregnant and nonpregnant women. While COW-CODA did result in minor misalignments in rare cases, it was clearly superior to the COW-TIC algorithm, especially when applied to highly variable chromatograms (factorial design, urine). The presented algorithm thus enables automatic time alignment and accurate peak matching of multiple LC-MS data sets obtained from complex body fluids that are often used for biomarker discovery.     

Calcium methoxide initiated ring-opening polymerization of ε-caprolactone and L-lactide

Summary A commercial calcium dimethoxide and an in-situ generated calcium methoxide prepared from bis(tetrahydrofuran)calcium bis[bis(trimethylsilyl)amide] and methanol, were investigated as initiators for the ring-opening polymerization of ε-caprolactone and L-lactide. Commercial calcium dimethoxide initiated rapid ε-caprolactone polymerization at 120°C in bulk to give quantitatively a polymer with a polydispersity index around 1.3. Significant racemization was observed for L-lactide polymerization. The In-situ formed calcium methoxide promoted the solution polymerization of both ε-caprolactone and L-lactide to high conversion at room temperature over a short time period, yielding the corresponding polyesters with narrow molecular weight distribution. NMR spectra showed that the poly(L-lactide) isolated had a purely isotactic microstructure. The initiator efficiency could be tuned by varying the molar ratio of methanol and bis(tetrahydrofuran)calcium bis[bis(trimethylsilyl)amide]. Received: 11 August 2000/Revised version: 21 December 2000/Accepted: 3 January 2001     

Share with strangers: Privacy bubbles as user-centered privacy control for mobile content sharing applications

A continually increasing number of pictures and videos is shared in online social networks. Current sharing platforms, however, only offer limited options to define who has access to the content. Users may either share it with individuals or groups from their social graph, or make it available to the general public. Sharing content with users to which no social ties exist, even if they were physically close to the places where content was created and witnessed the same event, is however not supported by most existing platforms. We thus propose a novel approach to share content with such users based on so-called privacy bubbles. Privacy bubbles metaphorically represent the private sphere of the users and automatically confine the access to the content generated by the bubble creator to people within the bubble. Bubbles extend in both time and space, centered around the collection time and place, and their size can be adapted to the user's preferences. We confirm the user acceptance of our concept through a questionnaire-based study with 175 participants, and a prototype implementation shows the technical feasibility of our scheme.     

Sumixam maximus gen.and sp.nov.,a New Pennsylvanian Species of Archaeorthoptera(Neoptera;Indiana,USA)

A new Mazon-Creek-type fossil specimen is described as Sumixam maximus gen. and sp. nov.,fossil relatives): it exhibits one of the diagnostic character states of this taxon, which is the fusion of CuA (emerging from M + CuA) with CuP, or a branch of it. A more precise taxonomic assignment is out of reach. The new taxon exhibits a fusion of the anterior branch of MA with RP, and a point of divergence of MA and MP located near the point of divergence of CuA (from M + CuA), but lack a branching of CuPa. This unique combination of character states is probably derived with respect to a number of contemporaneous species. Sumixam maximus gen. and sp. nov. is most likely the closest known relative of the panorthopterans, which include all the recent Archaeorthoptera.     

A new framework for evaluating potential risk of back disorders due to whole body vibration and repeated mechanical shock

A number of studies have examined the potential relationship between exposure to occupational vibration and low back pain associated with operation of vehicles. Only a handful of studies, however, have attempted to differentiate between the relative contributions of the steady state and transient mechanical shock components (the latter also being known as 'jarring and jolting', 'high acceleration event', 'multiple shocks' and 'impact') of the vibration exposure. The primary objective of this paper is to present a review of current studies that examine mechanical shock, present a case for the importance of evaluating both steady state and mechanical shock components and propose a new framework for evaluating the health effects due to occupational vibration exposure. A computerized bibliographical search of several databases was performed with special reference to the health effects of mechanical shock in relation to lower back disorders. Based on the analysis, eight experimental studies and nine epidemiological studies with relevance to exposure to 'mechanical shock' were identified. These studies suggested that rough vehicle rides are prevalent and that repeated exposure to mechanical shock may increase the risk of lower back pain. There is an urgent need for assessing the health effects of mechanical shocks in epidemiological studies. In particular, the new ISO 2631-5: International Organization for Standardization 2004 standard for shock exposure assessment should be evaluated with regard to musculoskeletal health effects.     

Adults' memories of childhood: True and false reports.

In 3 experiments, the authors examined factors that, according to the source-monitoring framework, might influence false memory formation and true/false memory discernment. In Experiment 1, combined effects of warning and visualization on false childhood memory formation were examined, as were individual differences in true and false childhood memories. Combining warnings and visualization led to the lowest false memory and highest true memory. Several individual difference factors (e.g., parental fearful attachment style) predicted false recall. In addition, true and false childhood memories differed (e.g., in amount of information). Experiment 2 examined relations between Deese/Roediger-McDermott task performance and false childhood memories. Deese/Roediger-McDermott performance (e.g., intrusion of unrelated words in free recall) was associated with false childhood memory, suggesting liberal response criteria in source decisions as a common underlying mechanism. Experiment 3 investigated adults' abilities to discern true and false childhood memory reports (e.g., by detecting differences in amount of information as identified in Experiment 1). Adults who were particularly successful in discerning such reports indicated reliance on event plausibility. Overall, the source-monitoring framework provided a viable explanatory framework. Implications for theory and clinical and forensic interviews are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mechanical behaviour in compression loading of 2D-composite materials made of carbon fabrics and a ceramic matrix

2D-carbon-carbon/ceramic composites, made from a 2D-carbon-carbon (2D-C-C) porous preform infiltrated with BN, SiC, TiC or B₄C, are mechanically characterized under compression loading in directions parallel or orthogonal to the carbon fabric layers. Three types of behaviour are observed: non-linear and time dependent behaviour, a quasi-linear domain and a pseudo-plastic behaviour related to damaging mechanisms. Underp-compression, the variations of the Young modulus as a function of compacity obey a parabolic or linear law depending on whether the material is weakly or highly densified. Undero-compression, an exponential law is observed whatever the densification degree. The variations of failure strength compacity follow similar laws. Phenomenological models are given which depict quite well the mechanical behaviours of the composites. Undero-compression, failure occurs as the result of damaging mechanisms taking place within the inter-layer ceramic bridges binding the fabric layers together. Underp-compression, a transition is observed, from interlayer delamination to intralayer failure, for a critical compacity of about 0.85 provided the infiltrated ceramic is strong enough (i.e. for SiC and TiC). Such a transition is assumed to also occur for 2D-C-C/B ₄ ^– C composites. On the contrary, for weak ceramic matrices (e.g. BN), failure inp-compression always occurs by delamination. The results suggest that the composite toughness could be increased by an optimization of the composite microstructure.