Die technische Implementierung neuronaler Netzwerke

Ebenso wie Digitalrechner sind neuronale Netzwerke, z.B. das Gehirn, informationsverarbeitende Systeme. Das ist aber auch schon fast die einzige Aehnlichkeit. Wie wir an uns selbst sehen, haben beide Arten von Systemen grundlegend verschiedene Faehigkeiten: Digitalrechner eignen sich ausgezeichnet zum schnellen und fast beliebig praezisen Rechnen mit Zahlen; dafuer wurden sie urspruenglich auch konstruiert. Andere Anwendungen kamen im Laufe der Zeit hinzu, z.B. die Verwaltung sehr gross er Informationsmengen in Datenbanken, d.h. Speicherung und gezieltes Wiederauffinden anhand einfacher Suchkriterien. Beides ist fuer den Menschen extrem muehsam. Hingegen bewaeltigt er mit Leichtigkeit Aufgaben, die selbst fuer die modernsten Parallelrechner noch unloesbar sind. Jedes Kind kann im Bruchteil einer Sekunde die Gesichter seiner Eltern von denen potentieller Feinde unterscheiden, weil dies einen evolutionaeren Vorteil darstellt. Neben den exzellenten Faehigkeiten zur Bildverarbeitung koennen wir mittels unseres neuronalen Netzwerks Sprache verstehen und den komplexen Muskelapparat unseres Koerpers mit phantastischer Genauigkeit kontrollieren. Allerdings muessen wir die meisten dieser Faehigkeiten erlernen, waehrend ein Digitalrechner seine Aufgaben erfuellt, sobald ein entsprechendes Programm entwickelt wurde

Duration of asynchronous operations in distributed systems

A distributed asynchronous system is investigated. Its processing elements execute common operations concurrently and distributively. They are implemented as combinatorial circuits and exchange data via open collector bus lines. A method is presented to identify and to minimize the duration of an operation and therefore to increase the performance of the system. No hardware modifications are required

Evaluation of a microbial muramidase supplementation on growth performance, apparent ileal digestibility, and intestinal histology of broiler chickens

The current study evaluated the effects of different inclusion levels of microbial muramidase (Muramidase 007, DSM Nutritional Products) on gastrointestinal functionality by determination of apparent ileal digestibility (AID) of nutrients, investigation of intestinal histomorphology, and quantification of resulting growth performance. Four maize-wheat-soybean experimental diets were produced without (C) and with different dosages of muramidase: low (L, 25,000 LSU(F)/kg), medium (M, 35,000 LSU(F)/kg), and high (H, 45,000 LSU(F)/kg); diets were fed to broilers for 35 d. At the end of the experiment, AID of ether extract (EE), crude protein (CP), Ca, and P were determined and samples of the mid-jejunum and -ileum were collected for histomorphological observations. Data were subjected to ANOVA analysis using the GLM procedure. Orthogonal polynomial contrasts were used to assess linear and quadratic effects of different levels of the muramidase. At the end of the trial, Muramidase 007 supplementation linearly increased body weight gain and decreased feed conversion ratio (FCR) (P ≤ 0.05). Adding the muramidase to broiler diets also linearly increased the European poultry efficiency factor (P ≤ 0.05). Inclusion of the muramidase in broiler diets linearly increased AID of CP, EE, and P (P ≤ 0.05), and the H group had a higher AID of EE and CP compared to C group (P ≤ 0.05). Microbial muramidase supplementation linearly increased ileal villus length to crypt depth ratio and decreased the number of ileal CD45 cells (P ≤ 0.05). Broilers fed M and H diets had fewer number of CD45 cells in the ileum compared to those in C group (P ≤ 0.05). In conclusion, the results of the present study demonstrated that inclusion of the microbial muramidase in broiler diets could increase AID of key nutrients and improve growth performance in broilers. Adding microbial muramidase to broiler diets can therefore be considered as an interesting prospect to improve gastrointestinal functionality. Biological mechanisms causing these improvements need to be studied further

MONNET: a software system for modular neural networks based on object passing

Modular neural networks integrate several neural networks and possibly standard processing methods. Tackling such models is a challenge, since various modules have to be combined, either sequentially or in parallel, and the simulations are time critical in many cases. For this, specific tools are prerequisite that are both flexible and efficient. We have developed the MONNET software system that supports the investigation of complex modular models. The design of MONNET is based on the object oriented paradigm, the environment is C++/UNIX. The basic concepts are dynamic modularity, object passing, scalability, reusability, and extensibility. MONNET features flexible and compact definition of complex simulations, and minimal overhead in order to run computationally demanding simulations efficiently

Improved 3-Line Hardware Synchronization

A new procedure is proposed to synchronize processors of a distributed system, which concurrently execute a common process consisting of a sequence of operations. The procedure is an extension of that used for the 1987 IEEE Futurebus Standard. It is based on global synchronization lines and a distributed synchronizer, and requires only minor modifications of existing hardware. The procedure allows to carry out two alternative synchronization protocols. As usual, an operation may be terminated by the last processor having finished its part of the operation. Alternatively, the operation may also be terminated by the first processor being ready. Application of this second procedure, e.g., to bus arbitration, allows to reduce the arbitration time in average by a factor of 2

Quantifying a critical training set size for generalization and overfitting using teacher neural networks

Teacher neural networks are a systematic experimental approach to study neural networks. A teacher is a neural network that is employed to generate the examples of the training and the testing set. The weights of the teacher and the input parts of the examples are set according to some probability distribution. The input parts are then presented to the teacher neural network and recorded together with its response. A pupil neural network is then trained on this data. Hence, a neural network instead of a real or synthetic application defines the task, according to which the performance of the pupil is investigated. One issue is the dependence of the training success on the training set size. Surprisingly, there exists a critical value above which the training error drops to zero. This critical training set size is proportional to the number of weights in the neural network. A sudden transition exists for the generalization capability, too: the generalization error measured on a large independent testing set drops to zero, and the effect of overfitting vanishes. Thus, there are two regions with a sudden transition in-between: below the critical training set size, training and generalization fails, and severe overfitting occurs; above the critical training set size, training and generalization is perfect and there is no overfitting

BMP is an important regulator of proepicardial identity in the chick embryo

AbstractThe proepicardium (PE) is a transient structure formed by pericardial coelomic mesothelium at the venous pole of the embryonic heart and gives rise to several cell types of the mature heart. In order to study PE development in chick embryos, we have analyzed the expression pattern of the marker genes Tbx18, Wt1, and Cfc. During PE induction, the three marker genes displayed a left–right asymmetric expression pattern. In each case, expression on the right side was stronger than on the left side. The left–right asymmetric gene expression observed here is in accord with the asymmetric formation of the proepicardium in the chick embryo. While initially the marker genes were expressed in the primitive sinus horn, subsequently, expression became confined to the PE mesothelium. In order to search for signaling factors involved in PE development, we studied Bmp2 and Bmp4 expression. Bmp2 was bilaterally expressed in the sinus venosus. In contrast, Bmp4 expression was initially expressed unilaterally in the right sinus horn and subsequently in the PE. In order to assess its functional role, BMP signaling was experimentally modulated by supplying exogenous BMP2 and by inhibiting endogenous BMP signaling through the addition of Noggin. Both supplying BMP and blocking BMP signaling resulted in a loss of PE marker gene expression. Surprisingly, both experimental situations lead to cardiac myocyte formation in the PE cultures. Careful titration experiments with exogenously added BMP2 or Noggin revealed that PE-specific marker gene expression depends on a low level of BMP signaling. Implantation of BMP2-secreting cells or beads filled with Noggin protein into the right sinus horn of HH stage 11 embryos resulted in downregulation of Tbx18 expression, corresponding to the results of the explant assay. Thus, a distinct level of BMP signaling is required for PE formation in the chick embryo

NERV: A Parallel Processor for Standard Genetic Algorithms

This paper describes the implementation of a standard genetic algorithm (GA) on the MIMD multiprocessor system NERV. It discusses the special features of the NERV hardware which can be utilized for an efficient implementation of a GA without changing the structure of the algorithm

VLSI Implementierung eines parallelen Hough-Transformations-Prozessors mit dynamisch nachladbaren Mustern

In 1.0 5m CMOS Technik wurde ein Prozessor zur parallelen Verarbeitung einer speziellen Hough-Transformation entwickelt. Bei der auf 50 MHz ausgelegten Taktfrequenz koennen 6.4 x 10E+10 Objektmuster pro Sekunde detektiert werden. Bis zu 5 x 10E+7 zu detektierende Suchmuster koennen pro Sekunde in den Prozessor geladen werden. Damit koennen erstmals Echtzeitapplikationen in der Bildverarbeitung im Mikrosekundenbereich erschlossen werden

On the I=2 channel pi-pi interaction in the chiral limit

An approximate local potential for the residual pi+ pi+ interaction is computed. We use an O(a**2) improved action on a coarse 9x9x9x13 lattice with approximately a=0.4fm. The results present a continuation of previous work: Increasing the number of gauge configurations and quark propagators we attempt extrapolation of the pi+ pi+ potential to the chiral limit.Comment: LATTICE98(spectrum) LaTeX2e, 3 pages, 3 eps figure