Memorizing by individuals and groups: A test of the pooling-of-ability model.

"Sixty-five Ss were given eight nonsense words to learn. Forty-two of the Ss learned the task in groups of three, and the remaining 23 learned the task as individuals… . The data indicate that a concept of group facilitation need not be introduced to explain the groups' performance." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Beiträge zur Psychophysik des Süßgeschmacks 5. Mitt. Untersuchungen zum Einsatz sequentieller Staircasemethoden bei der Bestimmung intensitätsgleicher Konzentrationspaare

Contributions to the psychophysics of sweet taste. Part 5. Investigations of the use of a sequential staircase-method for the determination of equal intense pairs of stimuli The suitability of a sequential staircase-method for the determination of equal stimuli of the gustatory sense is experimentally investigated. The aim is the decrease of experimental expenditure when ruling sources of bias. In order to realize them sucrose solutions are used both for the constant stimulus and also for the sequence of stimuli. Possible factors are the gradation of the sequence of stimuli and its displacement towards the constant stimulus. These are factorized in a two-staged trial arrangement and are interpreted in a form of an analysis of variance. The gradation of sequence (grain) is the key factor. It defines both the occasional bias and also the efficiency of systematical sources of bias. Thus the subject-depending judgement errors, which occur in larger gradation, are avoidable with their adjustment on the half of the difference threshold. The errors, which are due to the direction, are counterbalanced through an up and down trial execution with a following meaning average. A remaining influence of the displacement of sequence is normally neglective. The standard deviation for the single determination lies - independently of the concentration level - dimensionally slightly above the half of the setting grain. The method of constant stimuli requires at least the twofold experimental expenditure for a simular result.     

Another approach to the implementation of synchronization primitives

A new method for the implementation of synchronization primitives is described. The method combines the flexibility of user defined primitives with the possibility of compiler checks. The method allows the tailoring of the size and of the performance of the synchronization primitives to the needs of the user.     

Aminos?ureanalysen in biologischem Material I. Mitteilung Einflu? von Hydrolysenbedingungen sowie von Kohlenhydraten und Purinbasen

Zusammentassung Spezifische Zusammensetzung und Hydrolysenbedingungen sind von entscheidender Bedeutung für vergleichende Aminosäureanalysen in biologischem Material. Bei gleichen Proben ist mit einer standardisierten Methode eine Reproduzierbarkeit von etwa ±3% möglich, extreme Unterschiede in der Zusammensetzung führen aber zu verschiedenen Werten. So verursachen Kohlenhydrate erhebliche Verluste, die sich auf die einzelnen Aminosäuren sehr unterschiedlich verteilen. Hydrolyse mit Phenolzusatz bringt keine generelle Verbesserung. Analysenkontrolle mit Testsubstanzen sowie Differenzanalyse bei sehr geringen und unterschiedlichen Aminosäurenmengen verbessern die Analysentechnik. Die proteinfreie Stickstoff-Fraktion ermittelt aus dem Aminosäurenspektrum und Kjeldahl-Stickstoff betrug bei Hefen 4,7–14,1%. Die Konzentration der freien (Pool) und strukturgebundenen (Protein) Aminosäuren veränderte sich beim Waehstum der Hefen, bei Belüftung im Wasser (Verarmung) erfolgte nur bei den freien Aminosäuren eine Konzentrationsänderung.

---

Amino acid analysis in biological materials I. Influence of hydrolysis, carbohydrates and purin basis

Summary The specific composition and the condition of hydrolysis are very important for the comparative amino acid analysis of biological material. Wide differences in the composition of the biological material will give different results, the reproductivity with the standardized method with equal samples ranges within ± 3%. Carbohydrates for example cause a loss which is different with each amino acid. There is no improvement by addition of Phenol. Test substances as a controll of the analysis as well as difference analysis improve the analytical technique, when the sample contains some of the amino acids in very small amounts. The protein free fraction of yeasts was 4,7–14,1% when estimated by the amino acid spektrum and Kjeldahl nitrogen. There was a change in the composition of the amino acids in the pool and in the protein during growth of the yeast. Prolarged airation changes the concentration of the free amino acid pool only.

---

---

Herrn Professor Dr. H. Simon möchte ich für sein besonderes Interesse und die Förderung meiner Arbeit herzlich danken.     

Numerical simulation of piezoelectrically agitated surface acoustic waves on microfluidic biochips

Microfluidic biochips are biochemical laboratories on the microscale that are used for genotyping and sequencing in genomics, protein profiling in proteomics, and cytometry in cell analysis. There are basically two classes of such biochips: active devices, where the solute transport on a network of channels on the chip surface is realized by external forces, and passive chips, where this is done using a specific design of the geometry of the channel network. Among the active biochips, current interest focuses on devices whose operational principle is based on piezoelectrically driven surface acoustic waves (SAWs) generated by interdigital transducers placed on the chip surface. In this paper, we are concerned with the numerical simulation of such piezoelectrically agitated SAWs relying on a mathematical model that describes the coupling of the underlying piezoelectric and elastomechanical phenomena. Since the interdigital transducers usually operate at a fixed frequency, we focus on the time-harmonic case. Its variational formulation gives rise to a generalized saddle point problem for which a Fredholm alternative is shown to hold true. The discretization of the time-harmonic surface acoustic wave equations is taken care of by continuous, piecewise polynomial finite elements with respect to a nested hierarchy of simplicial triangulations of the computational domain. The resulting algebraic saddle point problems are solved by blockdiagonally preconditioned iterative solvers with preconditioners of BPX-type. Numerical results are given both for a test problem documenting the performance of the iterative solution process and for a realistic SAW device illustrating the properties of SAW propagation on piezoelectric materials. The first two authors have been supported by the DFG within the Collaborative Research Center SFB 438. The seond author acknowledges further support by the NSF under Grant No. DMS-0411403, Grant No. DMS-0412267 and Grant-No. DMS-0511611.     

Alternative choices for voltage-tunable dielectrics

Abstract

Barium strontium titanate (BST) has been exhaustively studied as a voltage tunable dielectric to the apparent exclusion of other materials. Since undoped BST shows dielectric losses which are higher than desirable, it is reasonable to seek alternative materials with characteristically lower losses. In this paper alternative dielectrics are introduced and compared with BST for their use in frequency-agile applications. Data are presented (capacitance and loss tangent as a function of field) for lead magnesium niobate and cadmium niobate materials which suggest that these dielectrics can be used to provide satisfactory levels of voltage tunability whilst at the same time exhibiting lower dielectric losses than BST.     

A reactive extrusion process for the free radical grafting of silanes onto polypropylene: Effects of processing conditions and properties of water cross‐linked silane‐grafted polypropylene

Silane grafting and water cross‐linking of polypropylene (PP) are a recent method to modify its properties, such as melt strength, heat, and chemical resistance. This work aims at grafting silanes onto PP by reactive extrusion. The occurrence of the grafting of silane onto PP was confirmed by Fourier transform infrared (FTIR) and a method based on FTIR was developed to quantify the amount of polymerized silane and that of silane grafted onto PP. The molar mass of the silane‐grafted PP and its melt viscosity were also measured. A multiobjective optimization strategy was used to study the effects of processing conditions on the quality of the silane‐modified PP. It was concluded that to maximize the amount of silane grafted on PP and minimize the amount of polymerized silane and the decrease in PP chain scission, screw speed and barrel temperature should be low and feed rate high. POLYM. ENG. SCI., 2013. © 2013 Society of Plastics Engineers