Exploring a Mechanistic Approach to Experimentation in Computing

The mechanistic approach in philosophy of science contributes to our understanding of experimental design. Applying the mechanistic approach to experimentation in computing is beneficial for two reasons. It connects the methodology of experimentation in computing with the methodology of experimentation in established sciences, thereby strengthening the scientific reputability of computing and the quality of experimental design therein. Furthermore, it pinpoints the idiosyncrasies of experimentation in computing: computing deals closely with both natural and engineered mechanisms. Better understanding of the idiosyncrasies, which manifest in terms of a nonstandard role for experimentation, are interesting both for computer scientists and for philosophers of science. Computer scientists can think more clearly about their experimental choices. The role of experimentation elucidated by computer science merits further study from philosophers of science generally, as it highlights a role for experimentation hitherto unrecognized by philosophers: demonstration that activities exist

Correlating domain registrations and DNS first activity in general and for malware

From the date that a domain name is registered with a registrar, there should be a pattern in the amount of time it takes for that domain to be actively resolved on the Internet. We first attempt to describe that pattern in general terms by correlating data from registries for several top-level domains and a large passive DNS data source. This pattern is then used as a baseline for a comparison with the pattern of activity in domains that malicious software utilizes. While our quantitative results are not to be considered representative of the patterns exhibited by all types of malware, the malicious domains are found to have a significantly different pattern than the standard domains

A natural carbohydrate fraction Actigen™ from Saccharomyces cerevisiae cell wall: effects on goblet cells, gut morphology and performance of broiler chickens

A study was conducted to evaluate a natural carbohydrate fraction Actigen™ (NCF), derived from mannanoligosaccharide, in feed on growth performance, intestinal morphology and goblet cell number and area of male broilers'. Dietary treatments included: 1) control diet (antibiotic and NCF free), 2) NCF at 200g/t, 3) NCF at 400g/t, and 4) NCF 800g/t. Two hundred and forty birds were placed into 12 replicate pens per treatment (5 birds/pen), sixty birds per treatment. Body weight and feed intake were recorded weekly up to day 42. At this time a 2.5cm section of jejunum and duodenum were excised post mortem for morphological analysis. Birds fed 200g/t and 800g/t NCF were significantly (P<0.01) heavier from day 14 onwards than the control birds. Feed intake was significantly higher in birds fed 200g/t NCF compared to those fed the control at 21 and 35 days (P<0.05). Diets containing 200g/t and 800g/t of NCF significantly decreased broiler feed conversion ratio (FCR) compared to the control in the first phase (1-14 days) (P<0.01) and levels of NCF decreased FCR (P<0.05) in the second phase (15-28 days). NCF had no significant effect on villus height, villus width, crypt depth or villus to crypt ratio in either duodenum or jejunum. NCF did not significantly affect goblet cell area or goblet cell number in the duodenum, however, in the jejunum, 800g/t NCF significantly (P<0.05) increased goblet cell area over the control. In conclusion, NCF showed a positive effect on broiler performance in the starter and grower phases, and increased goblet cell area in the jejunum, suggesting higher levels of mucin production. This indicated that the performance benefit of NCF could be age-dependent, with younger birds responding more than the older ones. There were no additional benefits to performance when feeding NCF for a longer period (after 28 d of age), however it is postulated that birds fed NCF would have greater defence to pathogenic challenge through increased storage capacity of muci

The Large Scale Curvature of Networks

Understanding key structural properties of large scale networks are crucial for analyzing and optimizing their performance, and improving their reliability and security. Here we show that these networks possess a previously unnoticed feature, global curvature, which we argue has a major impact on core congestion: the load at the core of a network with N nodes scales as N^2 as compared to N^1.5 for a flat network. We substantiate this claim through analysis of a collection of real data networks across the globe as measured and documented by previous researchers.Comment: 4 pages, 5 figure

Risk assessment of an offshore wind turbine and remaining useful life estimation of the power converter. Improving availability by prioritising failures with higher risk to operation

By 2014, almost 2500 offshore wind turbines were installed in Europe representing 8GW of capacity connected to the grid and, there is a growing market penetration for the next years. Offshore wind farm operators are facing many challenges related to disparate data sources utilisation for O&M logistic optimisation. Therefore, the decision-making process needs to be based on sound analysis of the wind farm information or data available. According to several technical reports operation and maintenance (O&M) cost could reach until 30% of the levelised cost of energy (LCOE). Understanding the reliability of an offshore wind turbine and the resources required to maintain it is crucial to reduce O&M costs and thus, to reduce the levelised cost of energy (LCOE). There is a need to reduce unnecessary tasks, prioritise the most urgent tasks, improve usage of vessels, crew and technicians, reduce the cost of spare parts held and schedule preventative maintenance to minimise downtime and maximise revenue. Currently, risk assessment plays an important role in the operation and maintenance (O&M) strategies of offshore wind farms. A comprehensive failure mode and effect analysis (FMEA) has been carried out to determine critical assemblies of a generic offshore wind turbine with an induction generator, three stages gearbox and monopile foundation. The main objectives of undertaking this comprehensive FMEA was to identify those failures with significant impact on the wind turbine operation and to identify or highlight areas of risk for maintainability and availability. The FMEA is validated with; widely-used data available in the public domain; Lloyd’s Register’s experience of working with wind farm operators and; Lloyd’s Register experience of working on reliability of the mechanical system of different industrial sectors for decades. The FMEA is further augmented and updated by the use of on-going measurements from operating wind farms. Yaw system, pitch system, power converter and gearbox have been identified in the FMEA as the most critical assemblies regarding risk to the turbine operation. Power converter analysis shows high failure rates and a large proportion of undetectable failures, therefore maintenance resources have been spent on fault finding with its corresponding cost. New approaches are necessary to tackle electrical or electronic failures, especially on the power converter. To improve overall reliability, a method to estimate the remaining useful life (RUL) of a fully-rated converter in a variable speed wind turbine is proposed using data commonly available for offshore wind farm operators. Studies show that the economic impact is dominated by failures related to power electronic components such as IGBTs and capacitors due to their higher repair cost. Mathematical models have been developed to correlate turbine operation variables and environmental conditions with failure root causes to define wear and maintenance actions based on the probability of failur

Effect of Pelleting Temperature on the Activity of Different Enzymes

The effects of different pelleting temperatures on the activity of cellulase, bacterial amylase, fungal amylase, and pentosanase were tested. Samples of a commercial barley-wheat-soybean diet containing different enzyme preparations were pelleted at 60, 70, 80, 90, and 100 C (pellet temperature measured at the die outlet) through a die containing holes 2.5 mm in diameter. Enzymatic analyses were conducted on either soluble substrates or by measuring the ability of the tested enzymes to decrease the viscosity of the diet. Measurements made on soluble substrates suggest that cellulase, fungal amylase, and pentosanase maintained activity when being pelleted at temperatures up to 80 C and bacterial amylase maintained activity at temperatures up to 90 C. Pentosanase and amylases showed little or no effect on the viscosity of the diet. Cellulase addition decreased the viscosity at all temperature levels, even after being pelleted at 90 and 100 C (P < 0.05). No cellulolytic activity was detected on the soluble substrate after these pelleting temperatures. Measurements on a soluble substrate might therefore not always reflect the true stability of a preparation because the ability of a carbohydrase to decrease the viscosity of the digesta is important to its effect in the gastrointestinal tract. Measurements on soluble substrates suggest that cellulase, fungal amylase, and pentosanase can be pelleted at temperatures up to at least 80 C and bacterial amylase up to 90 C without a considerable loss in analyzed activit

Futterbewertung im Umbruch? Beziehung zwischen dem Alter von Rindern und Ochsen aus einem Weidemastverfahren und Merkmalen der Fleischtextur (Zartheit)

Die Zartheit ist eines der wichtigsten Merkmale für den Genusswert von Fleisch und speziell für Labelfleischprogramme, aufgrund der Erkennbarkeit der Produkte, sicherlich von entscheidender Bedeutung für den wiederholten Kaufentscheid der Konsumierenden (Koohmaraie und Geesink, 2006). Ziel der vorliegenden Untersuchung war daher zu prüfen, inwieweit sich das Alter von Rindern und Ochsen, die auf der Basis von Gras und Graskonserven extensiv ausgemästet wurden, auf die Eigenschaften des Bindegewebes und die Textur von zwei Muskeln, die sich im Kollagengehalt unterscheiden, auswirkt

The effects of dietary mannaoligosaccharides on cecal parameters and the concentrations of enteric bacteria in the ceca of salmonella-challenged broiler chicks

The ability of different enteric pathogens and coliforms to trigger agglutination of yeast cells (Saccharomyces cerevisiae, NCYC 1026) and a yeast cell wall preparation (MOS) was examined. Five of seven strains of Escherichia coli and 7 of 10 strains of Salmonella typhimurium and Salmonella enteritidis agglutinated MOS and Sac. cerevisiae cells. Strains of Salmonella choleraesuis, Salmonella pullorum, and Campylobacter did not lead to agglutination. Two strains that agglutinated MOS (S. typhimurium 29E and Salmonella dublin) and one nonagglutinating strain (S. typhimurium 27A) were selected as challenge organisms for in vivo studies in chicks under controlled conditions. In a series of three trials in which 3-d-old chicks were orally challenged with 10(4) cfu of S. typhimurium 29E, birds receiving 4,000 ppm of dietary MOS had reduced cecal S. typhimurium 29E concentrations (5.40 vs 4.01 log cfu/ g; P < 0.05) at Day 10. In a second series of three trials with S. dublin as challenge organism, the number of birds that tested salmonella positive in the ceca at Day 10 was less when MOS was part of the diet (90 vs 56%; P < 0.05). To test the effect of MOS on concentrations of bacteria that do not express Type 1 fimbriae, a challenge trial was conducted with S. typhimurium 27A. However, strain 27A did not colonize the birds sufficiently to evaluate whether MOS affected its cecal concentration. Mannanoligosaccharide did not significantly reduce the concentrations of cecal coliforms (P < 0.10) although they were numerically lower. It had no effect on cecal concentrations of lactobacilli, enterococci, anaerobic bacteria, lactate, volatile fatty acid, or cecal p

Exome sequencing identifies nonsegregating nonsense ATM and PALB2 variants in familial pancreatic cancer.

We sequenced 11 germline exomes from five families with familial pancreatic cancer (FPC). One proband had a germline nonsense variant in ATM with somatic loss of the variant allele. Another proband had a nonsense variant in PALB2 with somatic loss of the variant allele. Both variants were absent in a relative with FPC. These findings question the causal mechanisms of ATM and PALB2 in these families and highlight challenges in identifying the causes of familial cancer syndromes using exome sequencing

Multidimensional cut-off technique, odd-dimensional Epstein zeta functions and Casimir energy of massless scalar fields

Quantum fluctuations of massless scalar fields represented by quantum fluctuations of the quasiparticle vacuum in a zero-temperature dilute Bose-Einstein condensate may well provide the first experimental arena for measuring the Casimir force of a field other than the electromagnetic field. This would constitute a real Casimir force measurement - due to quantum fluctuations - in contrast to thermal fluctuation effects. We develop a multidimensional cut-off technique for calculating the Casimir energy of massless scalar fields in $d$-dimensional rectangular spaces with $q$ large dimensions and $d-q$ dimensions of length $L$ and generalize the technique to arbitrary lengths. We explicitly evaluate the multidimensional remainder and express it in a form that converges exponentially fast. Together with the compact analytical formulas we derive, the numerical results are exact and easy to obtain. Most importantly, we show that the division between analytical and remainder is not arbitrary but has a natural physical interpretation. The analytical part can be viewed as the sum of individual parallel plate energies and the remainder as an interaction energy. In a separate procedure, via results from number theory, we express some odd-dimensional homogeneous Epstein zeta functions as products of one-dimensional sums plus a tiny remainder and calculate from them the Casimir energy via zeta function regularization.Comment: 42 pages, 3 figures. v.2: typos corrected to match published versio