Effect of storage temperature and size of stalks on quality of minimally processed leeks

Minimally processed leek stalks were produced by trimming of freshly harvested leeks (Allium porrum L.) to sizes of 0–22, 0–11 and 11–22 cm. Trimmed stalks were then stored at 0, 10 and 20 °C in air for 8 days to determine the effects of temperature and stalk size on quality during storage, including inner leaf growth, fresh weight loss and discoloration. Both inner leaf growth and fresh weight loss were increased linearly with storage duration. Growth of cut leek inner leaves was significantly reduced to 4 mm at the end of 0 °C storage in all three types of cut stalks. Inner leaf growth was maximized during storage at 10 and 20 °C in 0–11 cm stalks, medium in 0–22 cm stalks and minimal in 11–22 cm stalks. Fresh weight loss of 0–11 cm size was significantly higher than that of 0–22 cm size at both 0 and 10 °C, whereas there was no difference between 0–11 and 11–22 cm sizes. At 10 and 20 °C the 0–11 cm size lost more weight than the 11–22 and 0–22 cm ones. Differences in color attributes were observed in most cases between stalk sizes, due to different coloration of intact leeks. Discoloration was observed particularly at the stalk base at 20 °C. Low temperatures effectively control discoloration, and reduce considerably inner leaf growth of minimally processed leeks, but do not control it. Copyright © 2005 Society of Chemical Industry     

Exact reliability formulas for linear and circular m-consecutive-k-out-of-n:F systems

A linear (circular) m-consecutive-k-out-of-n:F system, consists of n components ordered on a line (on a circle). The system fails if and only if there are at least m nonoverlapping runs of k consecutive failed components. Four theorems are given. Theorem 1 is an exact formula of the reliability of the linear system given in terms of multinomial coefficients. Theorem 2 is an exact formula of the reliability of the linear system in terms of binomial coefficients. Theorems 3 and 4 are exact formulas of the reliability of the circular system, given in terms of multinomial and binomial coefficients, respectively.     

Preparation and hydration study of alinite cement

A laboratory alinite clinker was prepared at 1200°C by using industrial raw materials and adding 2.6% CaCl₂ to the raw mix. The structure of the clinker was studied by XRD and SEM. Three cements were prepared by intergrinding the clinker with 4, 6 and 8% gypsum. Compressive Strength development of these cements was studied up to 90 days. Hydration phenomena were also studied by XRD and SEM in pastes cured for 7, 28, and 90 days. Useful information is drawn concerning the structure of alinite clinker and the hydration phenomena of these cements.     

Authoring diagram-based CBA with CourseMarker

The CourseMarker system has been used to assess free-response computer based assessment (CBA) exercises since 1998. The aim of the studies reported here was to evaluate the feasibility and usefulness of developing and deploying diagram-based exercises using DATsys, an authoring environment for diagram-based CBA, together with CourseMarker. Postgraduate students constructed diagram-based exercises in four domains. The process of constructing the exercises was captured as an indicator of feasibility. The exercises were then used to assess two cohorts of undergraduate students. Instruments including system submission logs and student questionnaires were used to assess usefulness.Findings indicate that there is considerable potential for the assessment of free-response domains such as diagrams. Such an approach can help students as part of an iterative process of learning by allowing repeated submission of coursework, which may be most appropriate within a formative assessment context. The exercises are popular with students and demonstrate a gradual, though decelerating, increase in marks over subsequent submissions. The techniques are reliable, but further development allowing for alternative model solutions and assessment of the aesthetic appearance of diagrams would increase validity. Our techniques and findings are novel for CBA, and have implications for the increasingly important research area of formative assessment.     

Cross-community context management in Cooperating Smart Spaces

Recently, social networks have become the most prevalent IT paradigm, as the vast majority of Internet users maintain one or multiple social networking accounts. These accounts, irrespectively of the underlying service, contain rich information and data for the owner’s preferences, social skills, everyday activities, beliefs and interests. Along with these services, the computation, sensing and networking capabilities of the state of the art mobile and portable devices, with their always-on mode, assist users in their everyday lives. Thus, the integration of social networking services with current pervasive computing systems could provide the users with the potential to interact with other users that have similar interests, preferences and expectations; and in general, the same or similar context, for limited or not time periods, in order to ameliorate their overall experience, communicate, socialise and improve their everyday activities with minimal effort. This paper introduces a cross-community context management framework that is suitable for Cooperating Smart Spaces, which couple the advantages of pervasive computing and social networking. This framework goes beyond the state of the art, among others, in that cross-community context from a multitude of sources is collected and processed to enhance the end user experience and increase the perceived value of the services provided.     

A complexity perspective on entailment of parameterized linear constraints

Extending linear constraints by admitting parameters allows for more abstract problem modeling and reasoning. A lot of focus has been given to conducting research that demonstrates the usefulness of parameterized linear constraints and implementing tools that utilize their modeling strength. However, there is no approach that considers basic theoretical tools related to such constraints that allow for reasoning over them. Hence, in this paper we introduce satisfiability with respect to polyhedral sets and entailment for the class of parameterized linear constraints. In order to study the computational complexities of these problems, we relate them to classes of quantified linear implications. The problem of satisfiability with respect to polyhedral sets is then shown to be co- $\mathbb{NP}$ hard. The entailment problem is also shown to be co- $\mathbb{NP}$ hard in its general form. Nevertheless, we characterize some subclasses for which this problem is in ?. Furthermore, we examine a weakening and a strengthening extension of the entailment problem. The weak entailment problem is proved to be $\mathbb{NP}$ complete. On the other hand, the strong entailment problem is shown to be co- $\mathbb{NP}$ hard.     

A Network Game with Attackers and a Defender

Consider an information network with threats called attackers; each attacker uses a probability distribution to choose a node of the network to damage. Opponent to the attackers is a protector entity called defender; the defender scans and cleans from attacks some part of the network (in particular, a link), which it chooses independently using its own probability distribution. Each attacker wishes to maximize the probability of escaping its cleaning by the defender; towards a conflicting objective, the defender aims at maximizing the expected number of attackers it catches. We model this network security scenario as a non-cooperative strategic game on graphs. We are interested in its associated Nash equilibria, where no network entity can unilaterally increase its local objective. We obtain the following results:

Multispectral processing for color particle image velocimetry

Since the adoption of digital video cameras and cross-correlation methods for particle image velocimetry (PIV), the use of color images has largely been abandoned. Recently, however, with the re-emergence of color-based stereo and volumetric techniques, and the extensive use of color microscopy, color imaging for PIV has again become relevant. In this work, we explore the potential advantages of color PIV processing by developing and proposing new methods for handling multi-color images. The first method uses cross-correlation of every color channel independently to build a color vector cross-correlation plane. The vector cross-correlation can then be searched for one or more peaks corresponding to either the average displacement of several flow components using a color ensemble operation, or for the individual motion of colored particles, each with a different behavior. In the latter case, linear unmixing is used on the correlation plane to separate each known particle type as captured by the different color channels. The second method introduces the use of quaternions to encode the color data, and the cross-correlation is carried out simultaneously on all colors. The resulting correlation plane can be searched either for a single peak, corresponding to the mean flow or for multiple peaks, with velocity phase separation to determine which velocity corresponds to which particle type. Each of these methods was tested using synthetic images simulating the color recording of noisy particle fields both with and without the use of a Bayer filter and demosaicing operation. It was determined that for single-phase flow, both color methods decreased random errors by approximately a factor of two due to the noise signal being uncorrelated between color channels, while maintaining similar bias errors as compared to traditional monochrome PIV processing. In multi-component flows, the color vector correlation technique was able to successfully resolve displacements of two distinct yet coupled flow components with errors similar to traditional grayscale PIV processing of a single phase. It should be noted that traditional PIV processing is bound to fail entirely under such processing conditions. In contrast, the quaternion methods frequently failed to properly identify the correct velocity and phase and showed significant cross talk in the measurements between particle types. Finally, the color vector method was applied to experimental color images of a microchannel designed for contactless dielectrophoresis particle separation, and good results were obtained for both instantaneous and ensemble PIV processing. However, in both the synthetic color images that were generated using a Bayer filter and the experimental data, a significant peak-locking effect with a period of two pixels was observed. This effect is attributed to the inherent architecture of the Bayer filter. In order to mitigate this detrimental artifact, it is suggested that improved image interpolation or demosaicing algorithms tuned for use in PIV be developed and applied on the color images before processing, or that cameras that do not use a Bayer filter and therefore do not require a demosaicing algorithm be used for color PIV.     

Closed Formulas for the Failure Probability of a Strict-Consecutive-k-out-of-n:F System

A consecutive-k-out-of-n:F system is strict if it operates in such a way that isolated failure strings of length less than k (which do not cause system failure) do not occur, or are immediately corrected. This paper gives closed formulas for the failure probability of a strict-consecutive-k-out-of-n:F system.     

Decreased stature in gestational diabetes mellitus

Short stature has been associated with various degrees of abnormal glucose tolerance in middle-aged people, where the effects of age and metabolic control would be difficult to exclude. We chose to examine body stature in women with gestational diabetes mellitus (GDM), a prediabetic state affecting a young group of people. A sample of 2772 Greek pregnant women, referred for GDM screening was examined. After a 100-g oral glucose tolerance test, 1787 women were classified as normal (N), 300 women were found with one abnormal glucose value (OAV) and 685 women with GDM. Basal insulin resistance was calculated in 640 women by homeostasis model assessment. In addition, 51 pregnant women with pre-existing Type II (non-insulin-dependent) diabetes mellitus and 109 with pre-existing Type I (insulin-dependent) diabetes mellitus were included in the study. There was a gradual decrease in mean height (cm) as glucose intolerance became more severe: N: 161.0 +/- 6.2, OAV:160.2 +/- 6.1, GDM:158.7 +/- 6.3, Type II diabetes 158.2 +/- 7.0 (p < 0.001, analysis of variance]. Height in Type I diabetes (160.1 +/- 5.9) did not differ from the normal group. The difference in height between the normal and GDM groups remained (p < 0.001) when body weight, age, birth before or after 1960 and educational status were also taken into account. An independent correlation was also found between height and insulin resistance (n = 640) adjusted for the above mentioned variables. In conclusion, short stature appears to be associated with glucose intolerance as an independent variable, even when this intolerance is both mild and temporary. The previously unrecognised independent association of stature with basal insulin resistance merits further investigation.