Vergleich der Acrylamidaufnahme über die Nahrung bei Jugendlichen auf der Basis von Acrylamidgehalten von Januar 2003 und Oktober 2005

Auf der Basis von zwei Verzehrserhebungen – der Berliner Jugendstudie vom Herbst 2002 und der Nationalen Verzehrsstudie vom Ende der 80er Jahre – und Acrylamidwerten vom Stand Januar 2003 und Oktober 2005 wurde gesch?tzt, wie viel Acrylamid über die Nahrung aufgenommen worden ist. Ziel dieser Untersuchung war es, die Wirkung des Minimierungskonzepts des Bundesamtes für Verbraucherschutz und Lebensmittelsicherheit (BVL) in der betrachteten Bev?lkerungsgruppe zu belegen. Auf Basis der Verzehrsmengen der Berliner Jugendstudie ist eine Verringerung der mittleren t?glichen Acrylamidaufnahme durch den Verzehr der ausgew?hlten Lebensmittel von 1,08 μg auf 0,81 μg pro kg K?rpergewicht zu beobachten. Das entspricht einer Reduzierung um ca. 25%, die auf gesunkene Acrylamidwerte der betrachteten Produktgruppen zurückzuführen ist. Etwa identische Ergebnisse bezüglich der Reduzierung sind zu verzeichnen, wenn die Nationale Verzehrsstudie zugrunde gelegt wird. Auf Basis dieser Daten reduziert sich die mittlere t?gliche Acrylamidaufnahme pro kg K?rpergewicht von 0,91 μg auf 0,70 μg um ca. 23%.     

Computational geometry algorithms for the systolic screen

Adigitized plane of sizeM is a rectangular M × M array of integer lattice points called pixels. A M × M mesh-of-processors in which each processorP _ij represents pixel (i,j) is a natural architecture to store and manipulate images in ; such a parallel architecture is called asystolic screen. In this paper we consider a variety of computational-geometry problems on images in a digitized plane, and present optimal algorithms for solving these problems on a systolic screen. In particular, we presentO(M)-time algorithms for determining all contours of an image; constructing all rectilinear convex hulls of an image (peeling); solving the parallel and perspective visibility problem forn disjoint digitized images; and constructing the Voronoi diagram ofn planar objects represented by disjoint images, for a large class of object types (e.g., points, line segments, circles, ellipses, and polygons of constant size) and distance functions (e.g., allL _p metrics). These algorithms implyO(M)-time solutions to a number of other geometric problems: e.g., rectangular visibility, separability, detection of pseudo-star-shapedness, and optical clustering. One of the proposed techniques also leads to a new parallel algorithm for determining all longest common subsequences of two words.Research supported by the Naural Sciences and Engineering Research Council of Canada. With the Editor-in-Chief's permission, this paper was sent to the referees in a form which kept them unaware of the fact that the Guest Editor is one of the co-authors.     

PnP: sequential, external memory, and parallel iceberg cube computation

We present “Pipe ’n Prune” (PnP), a new hybrid method for iceberg-cube query computation. The novelty of our method is that it achieves a tight integration of top-down piping for data aggregation with bottom-up a priori data pruning. A particular strength of PnP is that it is efficient for all of the following scenarios: (1) Sequential iceberg-cube queries, (2) External memory iceberg-cube queries, and (3) Parallel iceberg-cube queries on shared-nothing PC clusters with multiple disks. We performed an extensive performance analysis of PnP for the above scenarios with the following main results: In the first scenario PnP performs very well for both dense and sparse data sets, providing an interesting alternative to BUC and Star-Cubing. In the second scenario PnP shows a surprisingly efficient handling of disk I/O, with an external memory running time that is less than twice the running time for full in-memory computation of the same iceberg-cube query. In the third scenario PnP scales very well, providing near linear speedup for a larger number of processors and thereby solving the scalability problem observed for the parallel iceberg-cubes proposed by Ng et al. Research partially supported by the Natural Sciences and Engineering Research Council of Canada. A preliminary version of this work appeared in the International Conference on Data Engineering (ICDE’05).     

Vergleich der Acrylamidaufnahme über die Nahrung bei Jugendlichen auf der Basis von Acrylamidgehalten von Januar 2003 und Oktober 2005

Zusammenfassung. Auf der Basis von zwei Verzehrserhebungen – der Berliner Jugendstudie vom Herbst 2002 und der Nationalen Verzehrsstudie vom Ende der 80er Jahre – und Acrylamidwerten vom Stand Januar 2003 und Oktober 2005 wurde gesch?tzt, wie viel Acrylamid über die Nahrung aufgenommen worden ist. Ziel dieser Untersuchung war es, die Wirkung des Minimierungskonzepts des Bundesamtes für Verbraucherschutz und Lebensmittelsicherheit (BVL) in der betrachteten Bev?lkerungsgruppe zu belegen. Auf Basis der Verzehrsmengen der Berliner Jugendstudie ist eine Verringerung der mittleren t?glichen Acrylamidaufnahme durch den Verzehr der ausgew?hlten Lebensmittel von 1,08 μg auf 0,81 μg pro kg K?rpergewicht zu beobachten. Das entspricht einer Reduzierung um ca. 25%, die auf gesunkene Acrylamidwerte der betrachteten Produktgruppen zurückzuführen ist. Etwa identische Ergebnisse bezüglich der Reduzierung sind zu verzeichnen, wenn die Nationale Verzehrsstudie zugrunde gelegt wird. Auf Basis dieser Daten reduziert sich die mittlere t?gliche Acrylamidaufnahme pro kg K?rpergewicht von 0,91 μg auf 0,70 μg um ca. 23%. Eingegangen: 2. August 2006     

Influence of food processing on the immunochemical stability of celery allergens

Celery roots were processed by microwave heating, cooking, drying, γ-irradiation, ultra high pressure treatment and high voltage impulse treatment. The immunochemical stabilities of the three known allergenic structures of celery were tested with sera from patients who were sensitised to celery. In addition, rabbit antisera were used to detect the allergens profilin and Api g 1 on celery immunoblots. The specificity and reactivity of IgE from the patients' sera were investigated by immunoblotting, by an enzyme allergosorbent test (EAST) and by dose-related IgE inhibition experiments. The results of all three methods agreed closely and indicated high antigenic and allergenic activity in native celery which was reduced by thermal processing. The heat-stability of the known celery allergens decreased in the following order: carbohydrate epitopes> profilin>Api g 1. In contrast, the allergenicity was only mildly reduced by non-thermal processing. The results obtained with human IgE were confirmed by an in vitro mediator-release assay that is based on rat basophil leukemia cells (RBL cells) which were passively sensitised with celery-specific murine IgE. With sera from mice that had been immunised with native celery, the native sample and non-thermal celery preparations elicited the strongest mediator release, whereas a weak response was obtained with samples from heat-processed celery. These results agreed closely with the data obtained in allergic patients whose IgE antibodies were directed against the major protein allergen Api g 1. Our results may be helpful in risk assessment and in selecting food preparations which can be consumed without symptoms by a subgroup of celery-allergic patients with a known sensitisation pattern. ©1997 SCI     

Optimal visibility algorithms for binary images on the hypercube

Consider an×n binary image. Given a directionD, the parallel visibility problem consists of determining for each pixel of the image the portion that is visible (i.e., not obstructed by any other black pixel of the image) in directionD from infinity. A related problem, referred to as point visibility, is to compute for each pixel the portion that is visible from a given pointp. In this paper, we deriveO(logn) time SIMD algorithms for each of these two problems on the hypercube, where one processor is assigned to every pixel of the image. Since the worst case communication distance of two processors in an ²-processor hypercube is 2 logn, it follows that both of the above algorithms are asymptotically optimal.This paper summarizes a preliminary version [Ref. 1] and short note on a possible improvement [Ref. 2] presented at the 1988IFIP WG 10.3. Working Conference on Parallel Processing and 1988Allerton Conference on Communication, Control and Computing, respectively. The first and third authors' research are partially supported by the Natural Sciences and Engineering Research Council of Canada.     

Translation separability of sets of polygons

We consider the problem of separating a set of polygons by a sequence of translations (one such collision-free translation motion for each polygon). If all translations are performed in a common direction the separability problem so obtained has been referred to as the uni-directional separability problem; for different translation directions, the more general multi-directional separability problem arises. The class of such separability problems has been studied previously and arises e.g. in computer graphics and robotics. Existing solutions to the uni-directional problem typically assume the objects to have a certain predetermined shape (e.g., rectangular or convex objects), or to have a direction of separation already available. Here we show how to compute all directions of unidirectional separability for sets of arbitrary simple polygons.The problem of determining whether a set of polygons is multi-directionally separable had been posed by G.T. Toussaint. Here we present an algorithm for solving this problem which, in addition to detecting whether or not the given set is multidirectionally separable, also provides an ordering in which to separate the polygons. In case that the entire set is not multi-directionally separable, the algorithm will find the largest separable subset.Research supported by NSERC under grant No. A9173 and A0392, respectively