Liquid Chromatography–High-Resolution Mass Spectrometry for Quantitative Analysis of Gangliosides

Gangliosides are a large family of glycosphingolipids that are abundant in the brain, and have been shown to affect neuronal plasticity during development, adulthood, and aging. We developed a fast, efficient, and sensitive liquid chromatography–mass spectrometry method to quantify eight different classes of gangliosides (GM₁, GM₂, GM₃, GD₃, GD_1a, GD_1b, GT_1b, GQ_1b) in the brains of 2-day-old and 80-day-old Wistar rats. The gangliosides were extracted from rat brain using a modified Svennerholm and Fredman method. After ganglioside class separation using a hydrophilic high performance liquid chromatography (HPLC) column, the resolving power of the LTQ-Orbitrap™ mass spectrometer was used to extract and sum the major species of each ganglioside class, generating fully resolved extracted ion current peaks for both standards and samples. The flexibility and the specificity of this method are such that it can be applied to the analysis of other ganglioside species/classes not discussed in this paper, provided appropriate standards are available. The method had good repeatability (coefficient of variation 4.8–12.3%) and mean recoveries in the range 92–107%.     

Selecting Workstations by Using a Cost/Benefit DSS

High-tech companies in the volatile microcomputer industry are facing a growing population of informed and technically enlightened buyers who have a broad base of workstation hardware from which to choose. As the process of selecting workstations becomes more complex, decision support becomes critical to aid buyers in making intelligent choices. This article describes a decision support system that was developed to assist buyers of workstations in selecting equipment with the highest benefit-to-cost rating.     

Mirror or Molder? A Study of Media Coverage,Stock Prices,and Trading Volumes in Germany

This article investigates the short‐term relationship between media coverage, stock prices, and trading volumes of eight listed German companies. A content analysis of news reports about the selected companies and a secondary analysis of the daily changes in closing prices and the trading volumes of these companies were combined in a time‐series design. After ARIMA‐modeling each of them, the results suggest that media coverage rather reflects than shapes the development at stock exchanges from a short‐term perspective (2 months). There were almost no hints for a widespread media effect, that is, an impact on so many investors that it will result in a measurable change in stock prices or trading volumes. Finally, theoretical and methodological consequences for exploring widespread media effects are discussed.     

Investigation of the microstructure of alkali-activated cements by neutron scattering

Significant research has been devoted to understanding and modeling the neutron scattering behavior of Portland cement pastes. The present work examines the potential of neutron scattering to noninvasively evaluate the properties of alternative cementitious materials encountered in the field. To interpret the scattering of both alkali-activated and slag-cement systems, alternative models to those typically adopted for Portland cement pastes were considered. Investigation of alkali-activated and slag-cement coupons were conducted for different sample thickness (∼0.5, 1, 2, 4, 6, 8 and 12 mm) over a wide scattering vector (Q) range (0.0005<Q>0.03 nm⁻¹ and 0.04<Q>4 nm⁻¹) on both ultra (USANS) and conventional small-angle neutron scattering (SANS) spectrometers. This wide Q range allowed determination of the fractal properties of the microstructure as well as the radius of the main scattering particle in the material. An empirical correction for multiple scattering was made based on the Dexter-Beeman equation and demonstrated that for thicker sample widths the theory correlated reasonably well. Alkali-activated fly ash was found to have the largest R value while the OPC and slag mix exhibited the largest Guinier radius. This difference was attributed to variations in the extent of multiple scattering for the samples. Successful application of this model was limited to sample thickness ≥1 mm. A combined power law-Sabine expression was also utilized to successfully model the SANS data over a Q range of 0.04-4 nm⁻¹.     

Statistical data analysis of magnetic recording noise mechanisms

Statistical data analysis using empirical eigenfunctions, known as the Karhunen-Loeve (K-L) expansion, is applied to characterize noise mechanisms in magnetic recording. Given any original data set and hence its correlation (covariance) matrix, an empirical orthogonal set of eigenfunctions can be obtained. The original data set can be expressed as an orthonormal expansion of these eigenfunctions. This feature of the K-L expansion can be used to study dominant noise profiles extracted from a large number of magnetization transition data. Two simple models of magnetization transitions are first utilized to investigate the validity of this expansion. Noises induced by transition center shifting (jitter), transition width fluctuation, amplitude modulation, and combined effects are respectively identified by the first several most important eigenfunctions in the expansion. Eigenfunction expansions of transition data obtained from experiments and numerical simulations are also obtained     

Visual discrimination by cats given lesions of visual cortex in one or two stages in infancy or in one stage in adulthood.

Sparing of visual function was studied in cats with bilateral cortical damage to Areas 17 and 18 and most of Area 19. Cats with lesions made in 2 stages, on Postnatal (P) Days 3 and 6, in 1 stage on P6, or in 1 stage in adulthood were compared with sham-operated controls on 10 visual discrimination tasks. On some tasks, both groups of cats that underwent surgery as infants showed considerable sparing of function compared with cats that had surgery as adults; the latter group showed a marked impairment. However, on several of the discriminations, 2-stage lesions permitted almost total sparing of pattern vision, whereas 1-stage lesions made neonatally were almost as debilitating as those incurred in adulthood. The findings suggest that differential behavioral consequences can follow physiological or anatomical changes, or both, that occur within a 4-day neonatal interoperative period. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Retinal vessels before and after photocoagulation in diabetic retinopathy. Determining the diameter using digitized color fundus slides

BACKGROUND: Retinal vessel diameter is an important parameter in blood flow analysis. Despite modern digital image technology, most clinical studies investigate diameters subjectively using projected fundus slides or negatives. In the present study we used a technique to examine vessel diameters by digital image analysis of color fundus slides. We investigated in a retrospective manner diameter changes in twenty diabetic patients before and after panretinal laser coagulation. MATERIAL AND METHODS: Color fundus slides were digitized by a new high resolution scanning device. The resulting images consisted in three channels (red, green, blue). Since vessel contrast was the highest in the green channel, we assessed grey value profiles perpendicular to the vessels in the green channel. Diameters were measured at the half-height of the profile. RESULTS: After panretinal laser coagulation, average venous diameter was decreased, whereas arterial diameter remained unchanged. There was no significant relation between the diameter change and the number of laser burns or the presence of neovascularization. CONCLUSIONS: Splitting digitized images into color planes enables objective measurements of retinal diameters in conventional color slides.     

Optimisation of Hamburg's wastewater treatment plants--three years of experience with the new concept.

In the end of the year 1999 a new concept for Hamburg's wastewater treatment plants was commissioned to cope with the additional load of 250,000 PE which has been connected to the existing plant serving 1.85 million population equivalents. The new concept consists of an additional tank for the storage of sludge liquor to avoid peak nitrogen concentrations in the effluent of the plant. This solution has been developed within a study assessing a wide range of concepts with costs between initial [see symbol in text] 100 million and the final construction costs of [see symbol in text]1 million. Here the dynamic simulation showed to be a very efficient planning tool. Within the first three years of operation the chosen solution showed to be able to fulfil the requirements. In 2002 the concept has been improved by a few more measures, mainly the equipment of one of the storage tanks as a SAT tank for further cost effective nitrogen removal. For a further improvement of the treatment capacity additional measures are planned to be carried out within the next years.     

Actor-observer asymmetries in explanations of behavior: New answers to an old question.

Traditional attribution theory conceptualizes explanations of behavior as referring to either dispositional or situational causes. An alternative approach, the folk-conceptual theory of behavior explanation, distinguishes multiple discrete modes of explanation and specific features within each mode. Because attribution theory and the folk-conceptual theory carve up behavior explanations in distinct ways, they offer very different predictions about actor-observer asymmetries. Six studies, varying in contexts and methodologies, pit the 2 sets of predictions against each other. There was no evidence for the traditional actor-observer hypothesis, but systematic support was found for the actor-observer asymmetries hypothesized by the folk-conceptual theory. The studies also provide initial evidence for the processes that drive each of the asymmetries: impression management goals, general knowledge, and copresence. (PsycINFO Database Record (c) 2010 APA, all rights reserved)