Validation of the Climate-SAF surface broadband albedo product: Comparisons with in situ observations over Greenland and the ice-covered Arctic Ocean

This paper describes a validation study performed by comparing the Climate-SAF Surface Albedo Product (SAL) to ground truth observations over Greenland and the ice-covered Arctic Ocean. We compare Advanced Very High Resolution Radiometer (AVHRR)-based albedo retrievals to data from the Greenland Climate Network (GCN) weather stations and the floating ice station Tara for polar summer 2007. The AVHRR dataset consists of 2755 overpasses. The overpasses are matched to in situ observations spatially and temporally. The SAL algorithm presented here derives the surface broadband albedo from AVHRR channels 1 and 2 using an atmospheric correction, temporal sampling of an empirical Bidirectional Reflectance Distribution Function (BRDF), and a narrow-to-broadband conversion algorithm. The satellite product contains algorithms for snow, sea ice, vegetation, bare soil, and water albedo. At the Summit and DYE-2 stations on the Greenland ice sheet, instantaneous SAL RMSE is 0.073. The heterogeneous surface conditions at satellite pixel scale over the stations near the Greenland west coast increase RMSE to > 0.12. Over Tara, the instantaneous SAL RMSE is 0.069. The BRDF sampling approach reduces RMSE over the ice sheet to 0.053, and to 0.045 over Tara. Taking into account various sources of uncertainty for both satellite retrievals and in situ observations, we conclude that SAL agrees with in situ observations within their limits of accuracy and spatial representativeness.     

Die Rolle der Informatik im gesellschaftlichen Diskurs: Eine Neupositionierung der Informatik

Zusammenfassung  Entwicklungen im Bereich der Informations- und Kommunikationstechnologie führen derzeit zu fundamentalen Umw?lzungen der Gesellschaft. Eine Beschleunigung des Lebens und das Verschwimmen von Beruf und Privatleben sind nur zwei Beispiele hierfür. Ein Abweichen von dem gesellschaftlichen Ideal des mobilen, jungen und dynamischen Mitarbeiters erweist sich h?ufig als Weg in das Einsiedlerdasein eines Exoten. Ein Widerstreben gegen die wachsenden Begehrlichkeiten von Wirtschaft und Staat l?sst das Individuum verd?chtig erscheinen und kann zu einer weiteren Entkopplung aus der Gesellschaft führen. Eine entscheidende Aufgabe bei gesellschaftlichen Umw?lzungen ist die der Reflexion und Kritik. Diese Rolle scheint mehr und mehr den Juristen zuzukommen. Insbesondere beim Thema Datenschutz erfolgt h?ufig eine Reduktion auf die Verfassungskonformit?t einzelner staatlicher Ma?nahmen. Kritik sollte jedoch bereits weit früher geübt werden. Medien sollten diese zentrale Funktion unterstützen und der politische Diskurs sollte zu einer optimalen L?sung führen. Eine Gruppe, die in der Debatte viel beitragen k?nnte und müsste, wird h?ufig, wenn überhaupt, aufgrund ihres technischen Sachverstandes herangezogen – die Informatiker. Dies ist insbesondere verwunderlich, da Informatiker ma?geblich an der Ver?nderung der Gesellschaft beteiligt sind. Sie schaffen die technischen Grundlagen für neue Formen der Interaktion. Doch das daraus resultierende Bild der Informatik als Computerwissenschaft beraubt Informatiker ihrer gesellschaftskritischen Funktion, da sie auf die Rolle von Technikern reduziert werden. Eine Positionierung und Darstellung der Informatik als Struktur- und Koordinationswissenschaft sowie der Informatiker als interdisziplin?re Systementwickler und -analytiker würde es Informatikern erm?glichen die bedeutende Rolle der Gesellschaftskritiker einzunehmen und geh?rt zu werden.     

Toward large-scale Hybrid Monte Carlo simulations of the Hubbard model on graphics processing units

One of the most efficient non-perturbative methods for the calculation of thermal properties of quantum systems is the Hybrid Monte Carlo algorithm, as evidenced by its use in large-scale lattice quantum chromodynamics calculations. The performance of this algorithm is determined by the speed at which the fermion operator is applied to a given vector, as it is the central operation in the preconditioned conjugate gradient iteration. We study a simple implementation of these operations for the fermion matrix of the Hubbard model in d+1 spacetime dimensions, and report a performance comparison between a 2.66 GHz Intel Xeon E5430 CPU and an NVIDIA Tesla C1060 GPU using double-precision arithmetic. We find speedup factors ranging between 30 and 350 for d=1, and in excess of 40 for d=3. We argue that such speedups are of considerable impact for large-scale simulational studies of quantum many-body systems.     

Using results of eye movement signal analysis in the neural network recognition of otoneurological patients

We extracted a collection of eye movement signals employed for almost two decades in clinical otoneurological tests at a balance laboratory. During those years we designed and programmed signal analysis methods to analyse their features in detail and to compute medically important attributes. In the present study, using such attributes and their results computed we classified test cases into groups of healthy subjects and patients with multilayer perceptron neural networks. Classification succeeded in total accuracies from 60% to 90% depending on the type of eye movements, which were saccades, nystagmus, sinusoidal movements and vestibulo-ocular reflex stimulated in two different ways; these are the chief eye movement tests applied in otoneurology.     

Bridging the physical and virtual worlds by local connectivity-based physical selection

The prevalent visions of ambient intelligence emphasise natural interaction between user and functions and services embedded in the environment or available through mobile devices. In these scenarios the physical and virtual worlds seamlessly gear into each other, making crossing the border between these worlds natural or even invisible to the user. The bottleneck in reaching these scenarios appear in the natural mapping between the physical objects and their virtual counterparts. The emergence of local connectivity in mobile devices opens possibilities for implementing novel user interface paradigms to enhance this mapping. We present physical selection paradigm for implementing an intuitive human technology interaction for mobile devices. In order to demonstrate the feasibility of the paradigm we implemented two experimental set-ups using commercially available smart phones with IrDA connectivity. The experiments involved selecting a website by physically pointing at its symbol and making a phone call by pointing at an icon representing the person to be called. In tentative user experiments the physical selection method was more time-efficient and it was perceived more positively by the users than a conventional method.

Exploring US Business Cycles with Bivariate Loops Using Penalized Spline Regression

The phrase business cycle is usually used for short term fluctuations in macroeconomic time series. In this paper we focus on the estimation of business cycles in a bivariate manner by fitting two series simultaneously. The underlying model is thereby nonparametric in that no functional form is prespecified but smoothness of the functions are assumed. The functions are then estimated using penalized spline estimation. The bivariate approach will allow to compare business cycles, check and compare phase lengths and visualize this in forms of loops in a bivariate way. Moreover, the focus is on separation of long and short phase fluctuation, where only the latter is the classical business cycle while the first is better known as Friedman or Goodwin cycle, respectively. Again, we use nonparametric models and fit the functional shape with penalized splines. For the separation of long and short phase components we employ an Akaike criterion.     

About the influence of the content and composition of the aggregates on the rheological behaviour of self-compacting concrete

Within the scope of a parameter study the influence of the mixture composition of different self-compacting concretes on the fresh concrete properties was investigated. For this purpose the standard test methods as well as the fresh concrete rheometer “BTRHEOM” were used. The concrete was modelled as a two-phase system, consisting of the fluid phase paste and the solid phase aggregates. The consistency control parameters paste volume, mortar volume and the coarse aggregate volume could be transferred into the model parameter thickness of excess paste. By means of this model parameter the characteristic values of the standard test methods like slump flow test and V-funnel test as well as the fundamental rheological parameters yield stress and the plastic viscosity could be described. A comparative study showed that the yield stress and the plastic viscosity of self-compacting concrete can be estimated based on the characteristic values of the slump flow test.     

Biological Role of the Intercellular Transfer of Glycosylphosphatidylinositol-Anchored Proteins: Stimulation of Lipid and Glycogen Synthesis

Glycosylphosphatidylinositol-anchored proteins (GPI-APs), which are anchored at the outer leaflet of plasma membranes (PM) only by a carboxy-terminal GPI glycolipid, are known to fulfill multiple enzymic and receptor functions at the cell surface. Previous studies revealed that full-length GPI-APs with the complete GPI anchor attached can be released from and inserted into PMs in vitro. Moreover, full-length GPI-APs were recovered from serum, dependent on the age and metabolic state of rats and humans. Here, the possibility of intercellular control of metabolism by the intercellular transfer of GPI-APs was studied. Mutant K562 erythroleukemia (EL) cells, mannosamine-treated human adipocytes and methyl-ß-cyclodextrin-treated rat adipocytes as acceptor cells for GPI-APs, based on their impaired PM expression of GPI-APs, were incubated with full-length GPI-APs, prepared from rat adipocytes and embedded in micelle-like complexes, or with EL cells and human adipocytes with normal expression of GPI-APs as donor cells in transwell co-cultures. Increases in the amounts of full-length GPI-APs at the PM of acceptor cells as a measure of their transfer was assayed by chip-based sensing. Both experimental setups supported both the transfer and upregulation of glycogen (EL cells) and lipid (adipocytes) synthesis. These were all diminished by serum, serum GPI-specific phospholipase D, albumin, active bacterial PI-specific phospholipase C or depletion of total GPI-APs from the culture medium. Serum inhibition of both transfer and glycogen/lipid synthesis was counteracted by synthetic phosphoinositolglycans (PIGs), which closely resemble the structure of the GPI glycan core and caused dissociation of GPI-APs from serum proteins. Finally, large, heavily lipid-loaded donor and small, slightly lipid-loaded acceptor adipocytes were most effective in stimulating transfer and lipid synthesis. In conclusion, full-length GPI-APs can be transferred between adipocytes or between blood cells as well as between these cell types. Transfer and the resulting stimulation of lipid and glycogen synthesis, respectively, are downregulated by serum proteins and upregulated by PIGs. These findings argue for the (patho)physiological relevance of the intercellular transfer of GPI-APs in general and its role in the paracrine vs. endocrine (dys)regulation of metabolism, in particular. Moreover, they raise the possibility of the use of full-length GPI-APs as therapeutics for metabolic diseases.     

Test-taking behaviors in a neurocognitive assessment: Associations with school-age outcomes in a Finnish longitudinal follow-up.

Test-taking behaviors (i.e., task focus, maintenance of attention, and cooperation) affect children's cognitive test performance, and, thus, it is critical to take test-taking behavior into account when drawing conclusions and making recommendations. Prior studies have evaluated test-taking behaviors at the end of the assessment; the present study focused on the fluctuation of cooperation and attention during a neuropsychological assessment. We examined the attention and cooperation of 5-year-old children in a test-taking situation; the associations between these aspects of their test-taking behavior and the children's concurrent neurocognitive test performance, IQ, and parent-rated behavior; and the associations with their IQ, behavioral outcomes, and academic achievement at 8 years of age. The data (for 76 boys and 63 girls) were drawn from the Jyv?skyl? Longitudinal Study of Dyslexia (Lyytinen et al., 2001, 2004). All the children were Caucasian and spoke Finnish as their native language. As a whole, the 5-year-old children showed high cooperation and attention, but a slight decrement in test-taking behavior toward the end of the session was rather common. Three subgroups of children with different levels of cooperation and attention were identified. Children in the subgroup with nonoptimal attention and cooperation showed decreasing neurocognitive test performance toward the end of the assessment session. They also showed more inattentive behavior 3 years later. The findings imply that the examiner's observations of waning attention and cooperation during the assessment session are highly relevant, as these provide stable and clinically meaningful information about the child's behavioral tendencies. (PsycINFO Database Record (c) 2011 APA, all rights reserved)