Properties of an h-Bernstein-like basis and curves

Blossoming is a useful technique to study bases and curve representations in computer-aided geometric design. Recently Simeonov et al. (Comput Aided Geom Des 28:549–565, 2011) have used a blossom generalization, namely the h-blossom, to derive new results about the h-Bernstein basis and h-Bézier curves that have previously been studied in approximation theory and computer-aided geometric design. This paper introduces a basis related to the h-Bernstein basis. There is a close relationship between this new basis and the h-Bernstein basis, between the new basis and the h-blossom, and between the new basis and “progressive” curves. This paper explores these relationships and uses them to derive properties both of the new basis itself, and of curves represented in terms of the new basis.     

Role of Context in Risk-Based Reasoning

In this article we report the influence of contextual factors on mathematics and science teachers' reasoning in risk-based decision-making. We examine previous research that presents judgments of risk as being subjectively influenced by contextual factors and other research that explores the role of context in mathematical problem-solving. Our own approach has been to develop carefully designed software tools that support the user to empathize with a hypothetical person, Deborah, who suffers from a medical condition. The tools were used by a group of teachers who were asked to help Deborah decide whether to have an operation that could cure the condition but which carries particular risks. In order to make this decision, the teachers were required to model the risks of the operation and also the lifestyle decisions that Deborah might make. We trace the teachers' efforts to coordinate judgments of likelihood and impact. The data emphasize the sensitivity of reasoning to matters of context; we set out in detail the various ways in which the process was affected by context.     

Separation of cold medicine ingredients using a precise MEKC method at elevated pH

An MEKC method was developed in order to separate a cold medicine formulation containing acetaminophen, ephedrine sulfate, doxylamine succinate, and dextromethorphan hydrobromide as active pharmaceutical ingredients. Because of their similar physical and chemical properties, it was a challenge to separate the basic compounds without sample pretreatment. In addition, the high content of alcohol and sucrose together with the variety of further excipients had to be considered. Thus, the complex matrix required several optimization steps. These included the search for the optimum pH and for a suitable sodium dodecyl sulfate concentration to avoid matrix-capillary wall interaction and to ensure precision. As a second developing step, an internal standard (benzocaine) was chosen to guarantee a high level of quantitative performance. An RSD% value of the peak areas between 1.0 and 2.0 was reached. The employed method development strategy can be generalized to similar separation approaches in the future.     

Evidence for non-chemical, non-electrical intercellular signaling in intestinal epithelial cells

Synchrony between mechanically separated biological systems is well known. We posed the question: can cells induce synchronous behavior in neighboring cells which are mechanically separated and which cannot communicate via chemical or electrical mechanisms. Caco-2 cell cultures were divided into three groups. "Inducer" cells were exposed to H(2)O(2). "Detector" cells were placed in separate containers near the inducer cells but were not exposed to H(2)O(2). Control cells were exposed to fresh media and were kept in a distant laboratory area. Samples were measured for total protein concentration, NFkappaB activation and structural changes, 10, 30 and 60 min after exposure respectively. Exposing inducer cells to H(2)O(2) resulted in a significant reduction in total protein content (-50%), an increase in nuclear NFkappaB activation (+38%), and structural damage (56%) compared to controls. There was a similar reduction in total protein content (-48%), increase in the nuclear fraction of NFkappaB (+35%) and structural damage (25%) in detector cells. These findings provide evidence in support of a non-chemical, non-electrical communication. This signaling system possibly plays a role in synchronous, stimulus-appropriate cell responses to noxious stimuli and may explain a number of cellular behaviors that are hard to explain based only on conventional cell signaling systems.     

Simulation of high- and low-resolution mass spectra for assessment of calibration methods

Calibrating mixtures of residual gases in quadrupole mass spectrometry (QMS) can be difficult since low m/z ratios of molecular ions and their fragments result in overlap of signals especially in the lower mass regions. This causes problems in univariate calibration methods and encourages use of full spectral multivariate methods. Experimental assessment of regression methods has limitations since experimental sources of error can only be minimised and not entirely eliminated. A method of simulating full spectra at low and high resolution to accurate masses is described and these are then used for a calibration study of some popular linear regression methods [classical least squares regression (CLS), partial least squares (PLS), principal component regression (PCR)].     

A systematic evaluation of chip-based nanoelectrospray parameters for rapid identification of proteins from a complex mixture

HPLC-MS/MS is widely used for protein identification from gel spots and shotgun fractions. Although HPLC has well recognized benefits, this type of sample infusion also has some undesirable attributes: relatively low sample throughput, potential sample-to-sample carryover, time-varying sample composition, and no option for longer sample infusion for longer MS analyses. An automated chip-based ESI device (CB-ESI) has the potential to overcome these limitations. This report describes a systematic evaluation of the information-dependant acquisition (IDA) and sample preparation protocols for rapid protein identification from a complex mixture using a CB-ESI source compared with HPLC-ESI (gradient and isocratic elutions). Cytochrome c and a six-protein mixture (11-117 kDa) were used to develop an IDA protocol for rapid protein identification and to evaluate the effects of sample preparation protocols. MS (1-10 s) and MS/MS (1-60 s) scan times, sample concentration (50-500 fmol/microL), and ZipTipC(18) cleanup were evaluated. Based on MOWSE scores, protein coverage, experimental run time, number of identified proteins, and reproducibility, a 12.5 min experiment (22 cycles, each with one 3 s MS and eight 10 s MS/MS scans) was determined to be the optimal IDA protocol for CB-ESI. This work flow yielded up to 220% greater peptide coverage compared with gradient HPLC-ESI and provided protein identifications with up to a 2-fold higher throughput rate than either HPLC-ESI approach, whilst employing half the amount of sample over the same time frame. The results from this study support the use of CB-ESI as a rapid alternative to the identification of protein mixtures.     

Regulation of c-Src nonreceptor tyrosine kinase activity by bengamide A through inhibition of methionine aminopeptidases

Methionine aminopeptidases (MetAPs) remove the N-terminal initiator methionine during protein synthesis, a prerequisite step for N-terminal myristoylation. N-myristoylation of proto-oncogene c-Src is essential for its membrane association and proper signal transduction. We used bengamides, a family of general MetAP inhibitors, to understand the downstream physiological functions of MetAPs. c-Src from bengamide A-treated cells retained its N-terminal methionine and suffered a decrease in N-terminal myristoylation, which was accompanied by a shift of its subcellular distribution from the plasma membrane to the cytosol. Furthermore, bengamide A decreased the tyrosine kinase activities of c-Src both in vitro and in vivo and eventually delayed cell-cycle progression through G(2)/M. Thus, c-Src is a physiologically relevant substrate for MetAPs whose dysfunction is likely to account for the cell-cycle effects of MetAP inhibitors including bengamide A.     

Detecting naphthenic acids in waters by gas chromatography-mass spectrometry

Naphthenic acids (general formula C(n)H(2n+Z)O(2)) are water-soluble, toxic compounds found in petroleum and bitumen. Some of the current methods for detecting these acids in waters depend on measuring the presence of the carboxylic acid functional group, and therefore many of these methods also detect naturally occurring carboxylic acids that are not naphthenic acids. We report a procedure that includes liquid-liquid extraction, cleanup, and derivatization to form t-butyldimethylsilyl esters prior to gas chromatography-mass spectrometry (GC-MS) analysis. Using low- and high-resolution MS to detect the ion C(15)H(27)O(2)Si(+) (nominal m/z=267) is an excellent indicator of the presence of naphthenic acids at concentrations > or =10microgL(-1).