Modeling and Vibration Suppression for Telescopic Systems of Structural Members with Clearance

Telescopic systems of structural members with clearance are found in many applications, e.g., mobile cranes, rack feeders, fork lifters, stacker cranes (see Figure 1). Operating these machines, undesirable vibrations may reduce the performance and increase safety problems. Therefore, this contribution has the aim to reduce these harmful vibrations. For a better understanding, the dynamic behaviour of these constructions is analysed. The main interest is the overlapping area of each two sections of the above described systems (see markings in Figure 1) which is investigated by measurements and by computations. A test rig is constructed to determine the dynamic behaviour by measuring fundamental vibrations and higher frequent oscillations, damping coefficients, special appearances and more. For an appropriate physical model, the governing boundary value problem is derived by applying Hamilton’s principle and a classical discretisation procedure is used to generate a coupled system of nonlinear ordinary differential equations as the corresponding truncated mathematical model. On the basis of this model, a controller concept for preventing harmful vibrations is developed.

[Mass culling in the context of animal disease outbreaks--veterinarians caught between ethical issues and control policies]

In recent years controversial discussions arose during major animal disease outbreaks in the EU about the ethical soundness of mass culling. In contrast to numerous publications about ethical issues and laboratory animals/animal experiments, literature concerning ethical deliberations in the case of mass culling as a means of outbreak control remain scarce. Veterinarians in charge of decision about and implementation of mass culling actions find themselves in an area of conflict in between the officially required animal disease control policy and a public that is increasingly critical. Those veterinarians are faced with the challenge to defend the relevant decisions against all stakeholders and also themselves. In this context an interdisciplinary workshop was initiated in Switzerland in October 2007 with ethicians and (official) veterinarians from Germany, Switzerland and Austria. With the aim to identify ethical components of animal disease control for official veterinarians, talks and moderated group discussions took place. This article summarizes selected discussion points and conclusions.

Differential association of MUC5AC and CLCA1 expression in small cartilaginous airways of RAO-affected and control horses

REASONS FOR PERFORMING STUDY: Airway mucus accumulation is associated with indoor irritant and allergen exposure in horses with recurrent airway obstruction (RAO). Epidermal growth factor receptor (EGFR) and a chloride channel (calcium activated, family member 1; CLCA1) are key signalling molecules involved in mucin gene expression. OBJECTIVES: We hypothesised that exposure to irritants and aeroallergens would lead to increased expression of the mucin gene eqMUC5AC and increased stored mucosubstance in the airways of RAO-affected horses, associated with increased neutrophils and CLCA1 and EGFR mRNA levels. METHODS: We performed quantitative RT-PCR of eqMUC5AC, CLCA1 and EGFR; volume density measurements of intraepithelial mucosubstances; and cytological differentiation of intraluminal inflammatory cells in small cartilaginous airways from cranial left and right and caudal left and right lung lobes of 5 clinically healthy and 5 RAO-affected horses that had been exposed to indoor stable environment for 5 days before euthanasia. RESULTS: Neutrophils were increased in RAO-affected horses compared to clinically healthy controls. EqMUC5AC mRNA levels were positively correlated with both CLCA1 and EGFR mRNA levels in RAO-affected horses but only with CLCA1 in controls. The relationship between eqMUC5AC and CLCA1 differed in the 2 groups of horses with RAO-affected animals overexpressing CLCA1 in relation to eqMUC5AC. CONCLUSIONS: These data implicate CLCA1 as a signalling molecule in the expression of eqMUC5AC in horses but also suggest differential regulation by CLCA1 and EGFR between horses with RAO and those with milder degrees of airway inflammation.

The MIRELA framework: modeling and analyzing mixed reality applications using timed automata

Mixed Reality (MR) aims to link virtual entities with the real world and has many applications such as military and medical domains [JBL+00, NFB07]. In many MR systems and more precisely in augmented scenes, one needs the application to render the virtual part accurately at the right time. To achieve this, such systems acquire data related to the real world from a set of sensors before rendering virtual entities. A suitable system architecture should minimize the delays to keep the overall system delay (also called end-to-end latency) within the requirements for real-time performance. In this context, we propose a compositional modeling framework for MR software architectures in order to specify, simulate and validate formally the time constraints of such systems. Our approach is first based on a functional decomposition of such systems into generic components. The obtained elements as well as their typical interactions give rise to generic representations in terms of timed automata. A whole system is then obtained as a composition of such defined components. To write specifications, a textual language named MIRELA (MIxed REality LAnguage) is proposed along with the corresponding compilation tools. The generated output contains timed automata in UPPAAL format for simulation and verification of time constraints. These automata may also be used to generate source code skeletons for an implementation on a MR platform. The approach is illustrated first on a small example. A realistic case study is also developed. It is modeled by several timed automata synchronizing through channels and including a large number of time constraints. Both systems have been simulated in UPPAAL and checked against the required behavioral properties.

Public health risks of enterobacterial isolates producing extended-spectrum β-lactamases or AmpC β-lactamases in food and food-producing animals: an EU perspective of epidemiology, analytical methods, risk factors, and control options

The blaESBL and blaAmpC genes in Enterobacteriaceae are spread by plasmid-mediated integrons, insertion sequences, and transposons, some of which are homologous in bacteria from food animals, foods, and humans. These genes have been frequently identified in Escherichia coli and Salmonella from food animals, the most common being blaCTX-M-1, blaCTX-M-14, and blaCMY-2. Identification of risk factors for their occurrence in food animals is complex. In addition to generic antimicrobial use, cephalosporin usage is an important risk factor for selection and spread of these genes. Extensive international trade of animals is a further risk factor. There are no data on the effectiveness of individual control options in reducing public health risks. A highly effective option would be to stop or restrict cephalosporin usage in food animals. Decreasing total antimicrobial use is also of high priority. Implementation of measures to limit strain dissemination (increasing farm biosecurity, controls in animal trade, and other general postharvest controls) are also important.

Regulatory factors and control of anthrax toxin gene expression

Bacillus anthracis plasmid pXO1 carries genes for three anthrax toxin proteins, pag (protective antigen), cya (edema factor), and lef (lethal factor). Expression of the toxin genes is enhanced by two signals: CO$\sb2$/bicarbonate and temperature. The CO$\sb2$/bicarbonate effect requires the presence of pXO1. I hypothesized that pXO1 harbors a trans-acting regulatory gene(s) required for CO$\sb2$/bicarbonate-enhanced expression of the toxin genes. Characterization of such a gene(s) will lead to increased understanding of the mechanisms by which B. anthracis senses and responds to host environments.^ A regulatory gene (atxA) on pXO1 was identified. Transcription of all three toxin genes is decreased in an atxA-null mutant. There are two transcriptional start sites for pag. Transcription from the major site, P1, is enhanced in elevated CO$\sb2$. Only P1 transcripts are significantly decreased in the atxA mutant. Deletion analysis of the pag upstream region indicates that the 111-bp region upstream of the P1 site is sufficient for atxA-mediated increase of this transcript. The cya and lef genes each have one apparent transcriptional start site. The cya and lef transcripts are significantly decreased in the atxA mutant. The atxA mutant is avirulent in mice. The antibody response to all three toxin proteins is significantly decreased in atxA mutant-infected mice. These data suggest that the atxA gene product activates expression of the toxin genes and is essential for virulence.^ Since expression of the toxin genes is dependent on atxA, whether increased toxin gene expression in response to CO$\sb2$/bicarbonate and temperature is associated with increased atxA expression was investigated. I monitored steady state levels of atxA mRNA and AtxA protein in different growth conditions. The results indicate that expression of atxA is not influenced by CO$\sb2$/bicarbonate. Steady state levels of atxA mRNA and AtxA protein are higher at 37$\sp\circ$C than 28$\sp\circ$C. However, increased pag expression at high temperature can not be attributed directly to increased atxA expression.^ There is evidence that an additional factor(s) may be involved in regulation of pag. Expression of pag in strains overproducing AtxA is significantly decreased compared to the wildtype strain. A specific interaction of tagged-AtxA with the pag upstream DNA has not been demonstrated. Furthermore, four proteins in B. anthracis extract can be co-immunoprecipitated with tagged-AtxA. Amino-terminal sequence of one protein has been determined and found highly homologous to chaperonins of GroEL family. Studies are under way to determine if this GroEL-like protein interactions with AtxA and plays any role in atxA-mediated activation of toxin genes. ^

Early metacognitive abilities: The interplay of monitoring and control processes in 5- to 7-year-old children

The goal of the current investigation was to compare two monitoring processes (judgments of learning [JOLs] and confidence judgments [CJs]) and their corresponding control processes (allocation of study time and selection of answers to maximize accuracy, respectively) in 5- to 7-year-old children (N=101). Children learned the meaning of Japanese characters and provided JOLs after a study phase and CJs after a memory test. They were given the opportunity to control their learning in self-paced study phases, and to control their accuracy by placing correct answers into a treasure chest and incorrect answers into a trash can. All three age groups gave significantly higher CJs for correct compared to incorrect answers, with no age-related differences in the magnitude of this difference, suggesting robust metacognitive monitoring skills in children as young as 5. Furthermore, a link between JOLs and study time was found in the 6- and 7-year-olds, such that children spent more time studying items with low JOLs compared to items with high JOLs. Also, 6- and 7-year-olds but not 5-year-olds spent more time studying difficult items compared to easier items. Moreover, age-related improvements were found in children's use of CJs to guide their selection of answers: although children as young as 5 placed their most confident answers in the treasure chest and least confident answers in the trash can, this pattern was more robust in older children. Overall, results support the view that some metacognitive judgments may be acted upon with greater ease than others among young children.

Intermittent hemodialysis treatment in cefepime-induced neurotoxicity: Case report, pharmacokinetic modeling, and review of the literature

Cefepime is a broad-spectrum cephalosporin indicated for in-hospital treatment of severe infections. Acute neurotoxicity, an increasingly recognized adverse effect of this drug in an overdose, predominantly affects patients with reduced renal function. Although dialytic approaches have been advocated to treat this condition, their role in this indication remains unclear. We report the case of an 88-year-old female patient with impaired renal function who developed life-threatening neurologic symptoms during cefepime therapy. She was treated with two intermittent 3-hour high-flux, high-efficiency hemodialysis sessions. Serial pre-, post-, and peridialytic (pre- and postfilter) serum cefepime concentrations were measured. Pharmacokinetic modeling showed that this dialytic strategy allowed for serum cefepime concentrations to return to the estimated nontoxic range 15 hours earlier than would have been the case without an intervention. The patient made a full clinical recovery over the next 48 hours. We conclude that at least 1 session of intermittent hemodialysis may shorten the time to return to the nontoxic range in severe clinically patent intoxication. It should be considered early in its clinical course pending chemical confirmation, even in frail elderly patients. Careful dosage adjustment and a high index of suspicion are essential in this population.

Metacognitive monitoring and control in elementary school children: Their interrelations and their role for test performance

Contemporary models of self-regulated learning emphasize the role of distal motivational factors for student's achievement, on the one side, and the proximal role of metacognitive monitoring and control for learning and test outcomes, on the other side. In the present study, two larger samples of elementary school children (9- and 11-year-olds) were included and their mastery-oriented motivation, metacognitive monitoring and control skills were integrated into structural equation models testing and comparing the relative impact of these different constituents for self-regulated learning. For one, results indicate that the factorial structure of monitoring, control and mastery motivation was invariant across the two age groups. Of specific interest was the finding that there were age-dependent structural links between monitoring, control, and test performance (closer links in the older compared to the younger children), with high confidence yielding a direct and positive effect on test performance and a direct and negative effect on adequate control behavior in the achievement test. Mastery-oriented motivation was not found to be substantially associated with monitoring (confidence), control (detection and correction of errors), or test performance underlining the importance of proximal, metacognitive factors for test performance in elementary school children.

Dynamics of governance and control in inter-organizational software development

In recent years, development of information systems (IS) has rapidly changed towards increasing division of labor between firms. Two trends are emerging. First, client companies increasingly outsource software development to external service providers. Second, the formerly oligopolistic enterprise application software industry has started to disintegrate into focal partnership networks – so called platform ecosystems. Despite the increasing prominence of IS outsourcing and platform ecosystems, many of these inter-organizational partnerships fail to achieve expected benefits. Ineffective governance and control frequently plays a pivotal role in producing these failures. While designing effective governance and control mechanisms is always challenging, inter-organizational software development projects are often business-critical and exhibit additional dynamics and uncertainty. As a consequence governance and control have to be adapted over time. The three research projects included in this book provide a better understanding of how and why governance and control can be effectively adapted over time. The implications for successful management of inter-organizational software development projects are highly relevant for theory and practice.