Finding a Minimum-depth Embedding of a Planar Graph in <Emphasis Type="Italic">O</Emphasis>(<Emphasis Type="Italic">n</Emphasis><Superscript>4</Superscript>) Time

Consider an n-vertex planar graph G. The depth of an embedding Γ of G is the maximum distance of its internal faces from the external one. Several researchers pointed out that the quality of a planar embedding can be measured in terms of its depth. We present an O(n ⁴)-time algorithm for computing an embedding of G with minimum depth. This bound improves on the best previous bound by an O(nlog n) factor. As a side effect, our algorithm improves the bounds of several algorithms that require the computation of a minimum-depth embedding.     

Adaptive robust stabilization of continuous casting

Continuous casting processes can suffer from a disturbance effect, called “dynamic bulging”, that causes large oscillations of the mold level, significantly reduces the quality of the final product and may cause instability and damages. In this paper this effect is analyzed and a new integrated control strategy is presented capable of significantly reduce the dynamic bulging without slowing down the process. The strategy is based on the superposition of two effects, one derived from the prediction of the periodic components of the oscillations and the second based on a robust adaptation scheme. Simulation and experimental results underline the advantages of the proposed method.     

Collaborative traceability management: a multiple case study from the perspectives of organization,process, and culture

Requirements Engineering - Traceability is crucial for many activities in software and systems engineering including monitoring the development progress, and proving compliance with standards. In...     

Optimization of hybrid oil/water-swelling ethylene/propylene/diene monomer compounds

Hybrid swell packers are rubber products capable of swelling in (saline) water and hydrocarbon oils, by exploiting the hydrocarbon diffusion properties of an nonpolar elastomer with the osmotic swelling of a water absorbent (WA). In this study, a variety of modified natural and synthetic WAs and mixtures thereof have been screened in a rubber compound with respect to swelling in decalin, demineralized, and saline water, respectively. We aimed at achieving high and fast swelling in all used media. Mixing of the various WAs in an ethylene/propylene/diene monomer (EPDM)/carbon black masterbatch at an addition level of 75 phr did not pose any problems, although it was found that the WAs did affect the sulfur vulcanization. Decalin swelling of the vulcanizates is very fast, reaching high equilibrium swelling within 1.5 days. Swelling in demineralized or saline water is much slower, with up to 300% swelling in water and up to 100% swelling in saline water. Significant leaching of the organic WA from the EPDM vulcanizates to the water phase occurs. Some combinations of WAs show synergetic effects for swelling in water. To our knowledge, such a systematic study of hybrid swelling elastomers constitutes a novelty in the open literature.     

Mathematical modeling of retinal mosaic formation by mechanical interactions and dendritic overlap

The retina is a complex assembly of neurons packed into a three-layer structure containing five classes of cells. Each class of retinal cells is regularly arranged within its layer in an orderly configuration called the retinal mosaic. We have set up a mathematical model of retinal mosaic formation focusing on the actions of local mechanical forces on the neuron's cytoskeleton. The cytoskeleton has been modeled according to two approaches, one based on the tensegrity concept (a structure made of elastic and rigid elements), and the other based on a simple model with viscoelastic features. We have assumed causing deformation of their cytoskeleton, overlap of dendritic areas and movement of the neuron. Simulations based on these two models indicate that a random distribution of neurons reaches an orderly configuration by local and mechanical neuron interaction in the case in which the cytoskeleton is modeled using the tensegrity approach, but not when the neuron is modeled as a purely viscoelastic system. Considering that the main structural difference between the Maxwell model and the tensegrity model is that the latter model contains rigid elements whereas the former does not, this suggests that the presence of rigid components in the cytoskeleton of retinal neurons plays a key role in the formation processes of the retinal mosaic.     

Structural Alterations of Human Serum Albumin Caused by Glycative and Oxidative Stressors Revealed by Circular Dichroism Analysis

The aim of this work was to evaluate the ability of oxidative and glycative stressors to modify properties of human serum albumin (HSA) by analyzing markers of glycation (pentosidine) and oxidation (advanced oxidative protein products (AOPPs)) and assessing fluorescence and circular dichroism. HSA was incubated for up to 21 days with ribose, ascorbic acid (AA) and diethylenetriamine pentacetate (DTPA) in various combinations in order to evaluate influences of these substances on the structure of HSA. Ribose was included as a strong glycative molecule, AA as a modulator of oxidative stress, and DTPA as an inhibitor of metal-catalyzed oxidation. Ribose induced a significant increase in pentosidine levels. AA and DTPA prevented the accumulation of pentosidine, especially at later time points. Ribose induced a mild increase in AOPP formation, while AA was a strong inducer of AOPP formation. Ribose, in combination with AA, further increased the formation of AOPP. DTPA prevented the AA-induced generation of AOPP. Ribose was also a potent inducer of fluorescence at 335nm ex/385nm em, which is typical of pentosidine. AA and DTPA prevented this fluorescence. Circular dichroism showed complex results, in which AA and DTPA were strong modifiers of the percentages of the alpha-helical structure of HSA, while ribose affected the structure of HSA only at later time points.     

Raw milk from vending machines: Effects of boiling,microwave treatment,and refrigeration on microbiological quality

In Italy, the sale of raw milk from vending machines has been allowed since 2004. Boiling treatment before its use is mandatory for the consumer, because the raw milk could be an important source of foodborne pathogens. This study fits into this context with the aim to evaluate the microbiological quality of 30 raw milk samples periodically collected (March 2013 to July 2013) from 3 vending machines located in Molise, a region of southern Italy. Milk samples were stored for 72 h at 4°C and then subjected to different treatments, such as boiling and microwaving, to simulate domestic handling. The results show that all the raw milk samples examined immediately after their collection were affected by high microbial loads, with values very close to or even greater than those acceptable by Italian law. The microbial populations increased during refrigeration, reaching after 72 h values of about 8.0 log cfu/mL for Pseudomonas spp., 6.5 log cfu/mL for yeasts, and up to 4.0 log cfu/mL for Enterobacteriaceae. Boiling treatment, applied after 72 h to refrigerated milk samples, caused complete decontamination, but negatively affected the nutritional quality of the milk, as demonstrated by a drastic reduction of whey proteins. The microwave treatment at 900 W for 75 s produced microbiological decontamination similar to that of boiling, preserving the content in whey proteins of milk. The microbiological characteristics of raw milk observed in this study fully justify the obligation to boil the raw milk from vending machines before consumption. However, this study also showed that domestic boiling causes a drastic reduction in the nutritional value of milk. Microwave treatment could represent a good alternative to boiling, on the condition that the process variables are standardized for safe domestic application.     

Evolution of free amino acids during ripening of Caciocavallo cheeses made with different milks

The evolution of free amino acids (FAA) in Caciocavallo cheeses, made with cow milk (CC) and cow milk mixed with ewe (CE) and goat (CG) milk, was studied throughout ripening. In all Caciocavallo cheeses produced, the total free amino acid (TFAA) content increased during ripening. In general, the highest TFAA content was found in cow cheeses, and the lowest in CG cheeses, whereas CE cheeses ranged over an intermediate level. In all the analyzed samples, during ripening, the content of the individual FAA increased with the exception of arginine. Tyrosine and histidine were found only in CE samples from the middle to the end of ripening. The major FAA found throughout the whole ripening period, in all types of cheese, were leucine, phenylalanine, lysine, valine, asparagine, γ-aminobutyric acid, and ornithine. The TFAA and several AA showed significant differences in ripening time, whereas tyrosine and histidine showed significant differences in kinds of milk.