Equivalence of switching linear systems by bisimulation

A general notion of hybrid bisimulation is proposed for the class of switching linear systems. Connections between the notions of bisimulation-based equivalence, state-space equivalence, algebraic and input–output equivalence are investigated. An algebraic characterization of hybrid bisimulation and an algorithmic procedure converging in a finite number of steps to the maximal hybrid bisimulation are derived. Hybrid state space reduction is performed by hybrid bisimulation between the hybrid system and itself. By specializing the results obtained on bisimulation, also characterizations of simulation and abstraction are derived. Connections between observability, bisimulation-based reduction and simulation-based abstraction are studied.\ud \u

How we see ‘Y’: South African health sciences students’ and lecturers’ perceptions of Generation Y students

Background. Health sciences education in the 21st century must recognise the changing profile of students, which includes an understanding of thecharacteristics of Generation Y students (born between 1981 and 2000) as future healthcare professionals.Objective. To examine the perceptions of students and lecturers regarding Generation Y students in health sciences that might impact on teachingand learning in a South African setting.Methods. A quantitative research approach was used to determine undergraduate students’ and lecturers’ perceptions of Generation Y students in the Faculty of Health Sciences, University of the Free State, Bloemfontein, South Africa. Anonymous questionnaires were used to obtain information.Results. The study population included students (n=616) and lecturers (n=71). Despite some shared perceptions about generational  characteristics, students and lecturers differed significantly on many issues. Unlike lecturers, students perceived themselves as being ambitious (not arrogant) and possessing superior cognitive skills. Despite desiring a  vibrant and stimulating learning environment, students wanted face-to-face contact with lecturers. Poor intergenerational communication also emerged as a pertinent issue.Conclusion. Identification of intergenerational issues that may impact on teaching and learning may contribute to developing novel educationalapproaches acceptable to both lecturers and students

Changes in the genomic content of circulating Bordetella pertussis strains isolated from the Netherlands, Sweden, Japan and Australia: adaptive evolution or drift?

Abstract Background Bordetella pertussis is the causative agent of human whooping cough (pertussis) and is particularly severe in infants. Despite worldwide vaccinations, whooping cough remains a public health problem. A significant increase in the incidence of whooping cough has been observed in many countries since the 1990s. Several reasons for the re-emergence of this highly contagious disease have been suggested. A particularly intriguing possibility is based on evidence indicating that pathogen adaptation may play a role in this process. In an attempt to gain insight into the genomic make-up of B. pertussis over the last 60 years, we used an oligonucleotide DNA microarray to compare the genomic contents of a collection of 171 strains of B. pertussis isolates from different countries. Results The CGH microarray analysis estimated the core genome of B. pertussis, to consist of 3,281 CDSs that are conserved among all B. pertussis strains, and represent 84.8% of all CDSs found in the 171 B. pertussis strains. A total of 64 regions of difference consisting of one or more contiguous CDSs were identified among the variable genes. CGH data also revealed that the genome size of B. pertussis strains is decreasing progressively over the past 60 years. Phylogenetic analysis of microarray data generated a minimum spanning tree that depicted the phylogenetic structure of the strains. B. pertussis strains with the same gene content were found in several different countries. However, geographic specificity of the B. pertussis strains was not observed. The gene content was determined to highly correlate with the ptxP-type of the strains. Conclusions An overview of genomic contents of a large collection of isolates from different countries allowed us to derive a core genome and a phylogenetic structure of B. pertussis. Our results show that B. pertussis is a dynamic organism that continues to evolve.</p

The effect of goalkeepers adopting Muller-Lyer postures

Poster 5 - Motor Control: Neural Correlates/Sensorimotor/Motor Practice and Observation: no. 57The posture that a goalkeeper assumes can influence perceptions of his or her size and the motor behavior of an opponent. Van der Kamp & Masters (2008) showed that postures that mimicked an amputated Muller-Lyer illusion in a wings-out/arms-up configuration resulted in larger estimates of goalkeeper height than a wings-in/arms-down configuration. Furthermore, when participants threw to score in a handball goal, the shots were placed further from the arms-up goalkeeper, presumably because he was thought capable of covering a greater area of the goal. We aimed to verify that throwing behaviour was related to (mis-)perceptions of goalkeeper height and, by association, goalkeeper reach. A 1.9 m animated representation of a goalkeeper was projected onto a blank screen. The goalkeeper was shown in an arms-up (45 degrees above horizontal), arms-out (horizontal), or arms-down (45 degrees below horizontal) posture. The 3 postures were each shown 10 times in a random order. For each presentation 34 participants made two estimates of the goalkeeper’s maximum static reach, which was defined as the position of middle finger of the goalkeeper in the arms-out posture. Estimates were made by aiming a laser pointer and throwing a ball. The horizontal displacements of the aiming and throwing estimates from the actual position of middle finger (75 cm from the midline of the body) were measured. For the horizontal displacement measure, there was no significant difference between aiming and throwing estimates (p > .05), but a significant effect of posture, F(2, 66) = 10.1, p <.01. Participants perceived the hand closer to the midline of the body in the arms-down posture (67.4 cm) than the arms-up posture (75.2 cm). The findings corroborate previous work in suggesting that the goalkeeper can influence perceptions of his maximum reach and the motor behaviour of an opponent by adopting illusory postures. Further investigations need to address whether the effects are also mediated by hand position or perceptions of arm length rather than body height.published_or_final_versionThe 2010 Conference of the North American Society for the Psychology of Sport and Physical Activity (NASPSPA 2010), Tucson, AZ., 10-12 June 2010. In Journal of Sport and Exercise Psychology, 2010, v. 32 suppl., p. S12

A BUSINESS CASE STUDY FOR COMPARING THE MANUFACTURING OF IMPLANT-SUPPORTED DENTURE FRAMES THROUGH DIRECT METAL LASER SINTERING TO CONVENTIONAL CASTING AND MACHINING PROCESSES

Conference ProceedingsRetaining dentures in edentulous patients is a common problem which can be overcome through the use of implant-supported denture frames. These frames are conventionally manufactured through the lost wax investment casting processes or through computer aided machining in cobalt chrome. Although Additive Manufacturing (AM) processes are now commonly used in the manufacturing of crowns and bridges in dentistry, the manufacturing of implant-supported denture frames is less common. This study aimed to investigate the feasibility of manufacturing these frames through AM from a business point of view compared to conventional casting and machining. A case study is presented where a full overdenture frame is designed and manufactured in Titanium-6Aluminium-4Vanadium (Ti-6Al-4V) alloy through the Direct Metal Laser Sintering (DMLS) process. This is compared to manufacturing the same frame in cobalt chrome through traditional processes in terms of manufacturing time and cost. Results from the study showed that it is more expensive and takes longer to produce overdenture frames through DMLS compared to conventional manufacturing techniques. Although costs and time can be reduced by producing a number of frames simultaneously on the DMLS machine’s building platform, the manufacturing process is still not considered viable for overdenture frames from a business point of view

Expanding the Lorentz concept in magnetism

This is the final version. Available on open access from IOP Publishing via the DOI in this recordIn 1878, the Dutch physicist Hendrik Antoon Lorentz first addressed the calculation of the local electric field at an atomic site in a ferroelectric material, generated by all the other electric dipoles within the sample. This calculation, which applies equally well to ferromagnets, is taught in Universities around the World. Here we demonstrate that the Lorentz concept can be used to speed up calculations of the local dipolar field in square, circular, and elliptical shaped monolayers and thin films, not only at the center of the film, but across the sample. Calculations show that long elliptical and rectangular films should exhibit the narrowest ferromagnetic resonance (FMR) linewidth. In addition, discrete dipole calculations show that the Lorentz cavity field $\left({\mu }_{0}M/3\right)$ does not hold in tetragonal films. Depending on the ratio (b/a), the local field can be either less/greater than $\left({\mu }_{0}M/3\right):$ an observation that has implications for FMR. 3D simple cubic (SC) systems are also examined. For example, while most texts discuss the Lorentz cavity field in terms of a Lorentz sphere, the Lorentz cavity field still holds when a Lorentz sphere is replaced by a the Lorentz cube, but only in cubic SC, FCC and BCC systems. Finally, while the primary emphasis is on the discrete dipole–dipole interaction, contact is made with the continuum model. For example, in the continuous SC dipole model, just one monolayer is required to generate the Lorentz cavity field. This is in marked contrast to the discrete dipole model, where a minimum of five adjacent monolayers is required.Engineering and Physical Sciences Research Council (EPSRC

Genome-wide methylome analysis using MethylCap-seq uncovers 4 hypermethylated markers with high sensitivity for both adeno- and squamous-cell cervical carcinoma

Background: Cytology-based screening methods for cervical adenocarcinoma (ADC) and to a lesser extent squamous-cell carcinoma (SCC) suffer from low sensitivity. DNA hypermethylation analysis in cervical scrapings may improve detection of SCC, but few methylation markers have been described for ADC. We aimed to identify novel methylation markers for the early detection of both ADC and SCC. Results: Genome-wide methylation profiling for 20 normal cervices, 6 ADC and 6 SCC using MethylCap-seq yielded 53 candidate regions hypermethylated in both ADC and SCC. Verification and independent validation of the 15 most significant regions revealed 5 markers with differential methylation between 17 normals and 13 cancers. Quantitative methylation-specific PCR on cervical cancer scrapings resulted in detection rates ranging between 80% and 92% while between 94% and 99% of control scrapings tested negative. Four markers (SLC6A5, SOX1, SOX14 and TBX20) detected ADC and SCC with similar sensitivity. In scrapings from women referred with an abnormal smear (n = 229), CIN3+ sensitivity was between 36% and 71%, while between 71% and 93% of adenocarcinoma in situ (AdCIS) were detected; and CIN0/1 specificity was between 88% and 98%. Compared to hrHPV, the combination SOX1/SOX14 showed a similar CIN3+ sensitivity (80% vs. 75%, respectively, P>0.2), while specificity improved (42% vs. 84%, respectively, P < 10(-5)). Conclusion: SOX1 and SOX14 are methylation biomarkers applicable for screening of all cervical cancer types

Antibiotics for otitis media with effusion in children

BACKGROUND: Otitis media with effusion (OME) is characterised by an accumulation of fluid in the middle ear behind an intact tympanic membrane, without the symptoms or signs of acute infection. Since most cases of OME will resolve spontaneously, only children with persistent middle ear effusion and associated hearing loss potentially require treatment. Previous Cochrane reviews have focused on the effectiveness of ventilation tube insertion, adenoidectomy, nasal autoinflation, antihistamines, decongestants and corticosteroids in OME. This review, focusing on the effectiveness of antibiotics in children with OME, is an update of a Cochrane review published in 2012. OBJECTIVES: To assess the benefits and harms of oral antibiotics in children up to 18 years with OME. SEARCH METHODS: The Cochrane ENT Information Specialist searched the ENT Trials Register; Central Register of Controlled Trials (CENTRAL 2016, Issue 3); PubMed; Ovid EMBASE; CINAHL; Web of Science; ClinicalTrials.gov; ICTRP and additional sources for published and unpublished trials. The date of the search was 14 April 2016. SELECTION CRITERIA: Randomised controlled trials comparing oral antibiotics with placebo, no treatment or therapy of unproven effectiveness in children with OME. DATA COLLECTION AND ANALYSIS: We used the standard methodological procedures expected by Cochrane. MAIN RESULTS: Twenty-five trials (3663 children) were eligible for inclusion. Two trials did not report on any of the outcomes of interest, leaving 23 trials (3258 children) covering a range of antibiotics, participants, outcome measures and time points for evaluation. Overall, we assessed most studies as being at low to moderate risk of bias. We found moderate quality evidence (six trials including 484 children) that children treated with oral antibiotics are more likely to have complete resolution at two to three months post-randomisation (primary outcome) than those allocated to the control treatment (risk ratio (RR) 2.00, 95% confidence interval (CI) 1.58 to 2.53; number needed to treat to benefit (NNTB) 5). However, there is evidence (albeit of low quality; five trials, 742 children) indicating that children treated with oral antibiotics are more likely to experience diarrhoea, vomiting or skin rash (primary outcome) than those allocated to control treatment (RR 2.15, 95% CI 1.29 to 3.60; number needed to treat to harm (NNTH) 20). In respect of the secondary outcome of complete resolution at any time point, we found low to moderate quality evidence from five meta-analyses, including between two and 14 trials, of a beneficial effect of antibiotics, with a NNTB ranging from 3 to 7. Time periods ranged from 10 to 14 days to six months. In terms of other secondary outcomes, only two trials (849 children) reported on hearing levels at two to four weeks and found conflicting results. None of the trials reported data on speech, language and cognitive development or quality of life. Low quality evidence did not show that oral antibiotics were associated with a decrease in the rate of ventilation tube insertion (two trials, 121 children) or in tympanic membrane sequelae (one trial, 103 children), while low quality evidence indicated that children treated with antibiotics were less likely to have acute otitis media episodes within four to eight weeks (five trials, 1086 children; NNTB 18) and within six months post-randomisation (two trials, 199 children; NNTB 5). It should, however, be noted that the beneficial effect of oral antibiotics on acute otitis media episodes within four to eight weeks was no longer significant when we excluded studies with high risk of bias. AUTHORS' CONCLUSIONS: This review presents evidence of both benefits and harms associated with the use of oral antibiotics to treat children up to 16 years with OME. Although evidence indicates that oral antibiotics are associated with an increased chance of complete resolution of OME at various time points, we also found evidence that these children are more likely to experience diarrhoea, vomiting or skin rash. The impact of antibiotics on short-term hearing is uncertain and low quality evidence did not show that oral antibiotics were associated with fewer ventilation tube insertions. Furthermore, we found no data on the impact of antibiotics on other important outcomes such as speech, language and cognitive development or quality of life. Even in situations where clear and relevant benefits of oral antibiotics have been demonstrated, these must always be carefully balanced against adverse effects and the emergence of bacterial resistance. This has specifically been linked to the widespread use of antibiotics for common conditions such as otitis media

The course of newly presented unexplained complaints in general practice patients: a prospective cohort study

Objective. Newly presented unexplained complaints (UCs) are common in general practice. Factors influencing the transition of newly presented into persistent UCs have been scarcely investigated. We studied the number and the nature of diagnoses made over time, as well as factors associated with UCs becoming persistent. Finally, we longitudinally studied factors associated with quality of life (QoL). Methods. Prospective cohort study in general practice of patients presenting with a new UC. Data sources were case record forms, patient questionnaires and electronic medical registries at inclusion, 1, 6 and 12 months. Presence of complaints and diagnoses made over time were documented. Potential risk factors were assessed in mixed-effect logistic and linear regression models. Results. Sixty-three GPs included 444 patients (73% women; median age 42) with unexplained fatigue (70%), abdominal complaints (14%) and musculoskeletal complaints (16%). At 12 months, 43% of the patients suffered from their initial complaints. Fifty-seven percent of the UCs remained unexplained. UCs had (non-life-threatening) somatic origins in 18% of the patients. QoL was often poor at presentation and tended to remain poor. Being a male [odds ratio (OR) 0.6; 95% confidence interval (CI) 0.4-0.8] and GPs' being more certain about the absence of serious disease (OR 0.9; 95% CI 0.8-0.9) were the strongest predictors of a diminished probability that the complaints would still be present and unexplained after 12 months. The strongest determinants of complaint persistence [regardless of (un)explicability] were duration of complaints >4 weeks before presentation (OR 2.6; 95% CI 1.6-4.3), musculoskeletal complaint at baseline (OR 2.3; 1.2-4.5), while the passage of time acted positively (OR 0.8 per month; 95% CI 0.78-0.84). Musculoskeletal complaints, compared to fatigue, decreased QoL on the physical domain (4.6 points; 2.6-6.7), while presence of psychosocial factors decreased mental QoL (5.0; 3.1-6.9). Conclusion. One year after initial presentation, a large proportion of newly presented UCs remained unexplained and unresolved. We identified determinants that GPs might want to consider in the early detection of patients at risk of UC persistence and/or low Qo