Maximum likelihood analysis of algorithms and data structures

We present a new approach for an average-case analysis of algorithms and data structures that supports a non-uniform distribution of the inputs and is based on the maximum likelihood training of stochastic grammars. The approach is exemplified by an analysis of the expected size of binary tries as well as by three sorting algorithms and it is compared to the known results that were obtained by traditional techniques. Investigating traditional settings like the random permutation model, we rediscover well-known results formerly derived by pure analytic methods; changing to biased data yields original results. All but one step of our analysis can be automated on top of a computer-algebra system. Thus our new approach can reduce the effort required for an average-case analysis, allowing for the consideration of realistic input distributions with unknown distribution functions at the same time. As a by-product, our approach yields an easy way to generate random combinatorial objects according to various probability distributions.     

System specification experiments on a common benchmark

To contribute to the current effort toward the definition of a system-level design language, this article proposes a benchmark for system specification. The authors analyze the results of experiments using the benchmark with several languages     

Symbolic pole/zero calculation using SANTAFE

The aim of symbolic analysis is to gain insight into circuit behavior. To study the behavior of analog circuits, the locations of the poles and zeros have to be known. Unfortunately, no general method exists to calculate the poles and zeros symbolically for polynomials of degree greater than four from transfer functions in coefficient form. The CAD tool SANTAFE (Symbolic Analysis of Transfer Functions) applies the signal-flow graph method, which permits to keep the result in a factorized or partially factorized form. The graphic view provided by a signal-flow graph offers insight into the internal interactions between the circuit elements and, as will be demonstrated, enables the user to perform circuit knowledge-based approximations. A novel procedure based on symbolic Newton-iteration, accurately calculates high-order transfer functions in the desired pole/zero form. Another special routine, based on element weight ratios rather than numerical values, enables the simplification of large symbolic expressions without numerical values for each parameter. With the program SANTAFE, even large networks can be analyzed symbolically. This will be shown with an example of a wide band BiCMOS operational amplifier     

Pregnancy rates after timed AI of heifers following removal of intravaginal progesterone inserts

Reproductive performance of dairy heifers was compared for each of 2 synchronization protocols: The first group of 54 heifers was synchronized using intravaginal progesterone inserts (CIDR) plus estradiol cypionate (ECP) on d 0, PGF(2alpha) on d 7, and ECP again on d 8 (CIDR-ECP); a second group of 56 heifers was synchronized using CIDR and ECP on d 0, PGF(2alpha) on d 7, and GnRH on d 9 (CIDR-GnRH). All heifers received timed artificial insemination (TAI) at 48, 56, or 72 h after CIDR removal on d 7. Pregnancy diagnosis was conducted by ultrasonography 32 +/- 1 d post AI to confirm pregnancy and at 60 +/- 1 d post AI to determine embryo survival. Ovaries were monitored by ultrasonography daily from d 0 to 7 and twice daily from d 8 to ovulation to examine emergence of a new wave of follicles, size of the ovulatory follicle, and timing of ovulation on 15 heifers per protocol. New follicular development was detected 3.7 +/- 0.2 d after CIDR insertion. Heifers receiving CIDR-ECP had a shorter interval from CIDR removal to ovulation than heifers receiving CIDR-GnRH (63.8 +/- 3.0 vs. 71.6 +/- 2.3 h, respectively); however, ovulation occurred 39.8 +/- 3.0 h after ECP or 23.6 +/- 2.3 h after GnRH. Diameters of ovulatory follicles did not differ between treatments. Overall pregnancy rate for synchronized heifers was 60.1%, and embryo survival was 98%. Pregnancy rate for heifers synchronized with CIDR-ECP was 63.0% and similar to that in heifers synchronized with CIDR-GnRH (57.1%). Pregnancy rate was affected by time of AI for heifers synchronized using CIDR-ECP but not for those synchronized with CIDR-GnRH. Heifers in the CIDR-ECP group that were inseminated 56 h after CIDR removal had a higher pregnancy rate (81.0%) compared with heifers inseminated 48 (66.7%) or 72 h (50.0%) after CIDR removal. Either ECP or GnRH used in a CIDR-based TAI program in dairy heifers can achieve acceptable reproductive performance.     

Comparison of on-farm laboratory milk progesterone assays for identifying errors in detection of estrus and diagnosis of pregnancy

A field study was conducted in 10 commercial dairy herds to test the efficacy of a rapid enzyme-linked immunosorbent assay to identify errors in detection of estrus and diagnosis of pregnancy. Milk samples were collected at the milking following detection of estrus and on d 21 postinsemination. Progesterone was measured on-farm by an enzyme-linked immunosorbent assay and in the laboratory by radioimmunoassay. Agreement between the two methods of progesterone analysis (n = 820) was 89.8%. There were 93 cows (18.7%) by laboratory analysis and 126 cows (25.4%) by on-farm analysis for which concentration of progesterone in the sample collected at suspected estrus (n = 497) was higher than normal estrual values. Exclusion of these cases increased the overall accuracy of pregnancy diagnosis by 6.8 and 6.4% for laboratory and on-farm methods. Overall agreement between pregnancy diagnosis by milk progesterone at d 21 postinsemination and diagnosis by return to estrus or palpation of reproductive organs was 80.5 and 75.8% for laboratory and on-farm methods (75.0% and 69.7% for pregnant cows and 94.5 and 93.9% for nonpregnant cows). These results indicate that an enzyme-linked immunosorbent assay for milk progesterone performed on-farm was equal in accuracy to a laboratory radioimmunoassay for identifying errors in detection of estrus and diagnosis of pregnancy.     

A GC–MS-based metabonomic investigation of blood serum from irritable bowel syndrome patients undergoing intervention with acidified milk products

In the present study, the use of gas chromatography mass spectrometry (GC–MS)-based metabonomics to characterize blood serum in an intervention study of patients suffering from the common gastrointestinal disorder irritable bowel syndrome (IBS) was investigated. The patients included in the study consumed an acidified milk product with (n = 30) or without probiotics (n = 31) (Lactobacillus paracasei F19, Lactobacillus acidophilus LA-5 and Bifidobacterium lactis BB-12) for an 8-week period, and blood serum samples were collected before and after the intervention. Acidified milk is commonly used as a delivering vector for probiotics in commercial consumer settings. The serum samples were extracted and derivatized using N-Methyl-N-(trimethylsilyl) trifluoroacetamide (MSTFA), and GC–MS analysis was carried out. Multivariate data analysis including principal component analysis (PCA), orthogonal partial least squares-discriminant analysis (OPLS-DA), and S-plot was applied on the obtained GC–MS data, which revealed higher serum lactate, glutamine, proline creatinine/creatine, and aspartic acid levels and lower serum glucose levels after the intervention period for both treatment groups. Consequently, the present study indicated an effect of acidified milk consumption on the plasma metabolite profile, which was independent of a concomitant intake of probiotics. In addition, the present study demonstrates that GC–MS is a useful analytical technique for metabonomics studies of blood serum.     

Expert system for evaluation of reproductive performance and management.

A microcomputer expert system for dairy herd reproductive management was developed using an expert system shell and Turbo Pascal. The expert system initially examines the broad areas of days open, days to first breeding, detection of estrus, and conception rate to determine whether a problem exists. Interpretations ranging from "excellent" to "severe" were established for each trait. The system then selects an area for evaluation that has the largest negative influence on days open. Once an area has been selected for further evaluation, the expert system utilizes information from the user and DHI reports developed by the Dairy Records Processing Center in Raleigh, NC. These reports identify problems with conception categorized by production, parity, service number, days in milk, breed, and service sire. In addition, questions are presented by the expert system to isolate problems of accuracy of data, use of natural service, semen handling, AI technique, detection of estrus, signs of estrus, and other management areas. Recommendations and suggestions are given. Ten commercial herds having a conception rate less than 40% were evaluated by the expert system and by an extension reproduction specialist who supplied information for the system. Of 100 areas investigated, the expert system and extension specialist identified 47 as potential problem areas, agreeing on 85% of them. Most discrepancies resulted from the specialist applying a less restrictive standard when values were close to a preselected threshold.     

AI Approaches to Cognitive Systems – The Example of Spatial Cognition

Cognitive abilities can be studied by observing and interpreting natural systems or by developing artificial systems that interact with their environments in intelligent ways. Cognitive systems research connects both approaches. Typically, human requirements are in the focus of interest and systems are developed to interact with humans in as natural a way as possible. To achieve this goal, a deep understanding of human cognition is required. The present paper focuses on spatial cognition, i. e. the ability to perceive and conceive spatial environments and solve spatial tasks intelligently. It discusses artificial intelligence approaches to spatial cognition for supporting human activities.     

Solving hard qualitative temporal reasoning problems: Evaluating the efficiency of using the ORD-Horn class

While the worst-case computational properties of Allen's calculus for qualitative temporal reasoning have been analyzed quite extensively, the determination of the empirical efficiency of algorithms for solving the consistency problem in this calculus has received only little research attention. In this paper, we will demonstrate that using the ORD-Horn class in Ladkin and Reinefeld's backtracking algorithm leads to performance improvements when deciding consistency of hard instances in Allen's calculus. For this purpose, we prove that Ladkin and Reinefeld's algorithm is complete when using the ORD-Horn class, we identify phase transition regions of the reasoning problem, and compare the improvements of ORD-Horn with other heuristic methods when applied to instances in the phase transition region. Finally, we give evidence that combining search methods orthogonally can dramatically improve the performance of the backtracking algorithm.     

Effect of vacuum annealing on field emission from heavily phosphorus doped homoepitaxial (111) diamond

Vacuum anneal treatments effects on field emission properties of phosphorus doped diamond are discussed. The C1s core level of diamond is characterized by X-ray photoelectron spectroscopy (XPS). With increasing annealing temperature, firstly oxygen desorption takes place from surface, which induce surface reconstruction followed by graphitization of surface. Field emission properties, therefore, strongly depend on vacuum anneal temperature. The threshold voltage of diamond annealed at 900 °C is the lowest. Fowler–Nordheim plots indicate that diamond annealed at 900 °C has the lowest barrier height, which is in good agreement with electron affinities as measured on carbon reconstructed surface. Further increased annealing temperature induces surface graphitization, which causes a threshold voltage increase of field emission.