Impulsive loading on reinforced concrete slabs.

A number of reinforced concrete slabs have been exposed to blast and impact loading in order to access modes of slab behaviour under these extreme dynamic loadings. Two sizes of specimens were used; small scale slabs modelled the large slabs at 1: 2.5 scale. Impact loads were produced by a free falling hammer impacting coaxially onto a cylindrical bar of steel placed at rest in the centre of the slab. The steel bar was instrumented with electrical strain gauges which recorded the stress pulses produced by the impact. Blast loads were produced using explosive charges made of Plastic Explosive PE4. In most cases the charge used was hemispherical in shape and was placed centrally above the slab at close range standoffs, i.e. up to 10 times the radius of the charge. Additional blast tests were conducted in order to monitor the transient and spatial pressure distribution across the slab by using the pressure gauges placed in replica steel slab. Transient deflections of the slabs under both types of load were obtained using long stroke displacement transducers, whilst transient strains in the steel reinforcement of the slabs were obtained using electrical resistance strain gauges bonded to the steel bars at mid span point. A rotating prism high speed camera was used to film the damage on some of the small scale specimens at rates of up to 10,000 pictures per second. The Hopkinson pressure bar tests were used to obtain the dynamic characteristics of the concretes used at high rates of loading. Differeent concrete mixes were used for the 1:1 and 1:2.5 scale slabs. An analytical function of the spatial and transient blast pressure distribution based on the detonation pressure of PE4 was established. This is in close agreement to experimentally measured results. The nature of the local and overall failure are discussed, and the time sequence of the slab failure is established for the case of explosive loading. The crack pattern that occurs soon after the explosion in area of local failure has been established from the high speed films whilst the overall deflected shape was obtained from the displacement vs time records. After test scab sizes and slab perforations were used to establish a relation between the slab thickness, amount of explosive and the slab damage in respect to scabbing and perforation. The displacement records and the shape of after test damage provided the basis for comments on "gravity neglected - the ultimate strength" modelling law that was employed in this research

Development of teaching-modules in computational Mathematics and STACK in cooperation with students

We report a project assigned to two second year bachelor students. They create two modules that first year students in electronics test out in February 2017. In module one they create a small course in Computational Mathematics using Maxima to solve problems in Integration. In module two they create a training course in STACK. STACK is an advanced Computer Aided Assessment system for mathematics which goes well beyond relying on multiple choice and other selected response question types. In particular, random versions of a particular question are generated in a structured mathematical way. The main goal of the project is that, under staff guidance, students create a test in STACK for students in the following year. This is similar to “peer tutoring”, but involves peers in assessment design. The authors believe that it requires one to have a deeper understanding of a topic to make a test for another, and this is therefore a valid task for students themselves to seek to undertake. The teacher and developer of STACK will evaluate the quality of work the first year student groups deliver. The question is whether this approach helps students gain a better understanding of integrationpublishedVersionnivå

Indiscriminate Males: Mating Behaviour of a Marine Snail Compromised by a Sexual Conflict?

Background: In promiscuous species, male fitness is expected to increase with repeated matings in an open-ended fashion (thereby increasing number of partners or probability of paternity) whereas female fitness should level out at some optimal number of copulations when direct and indirect benefits still outweigh the costs of courtship and copulation. After this fitness peak, additional copulations would incur female fitness costs and be under opposing selection. Hence, a sexual conflict over mating frequency may evolve in species where females are forced to engage in costly matings. Under such circumstance, if females could avoid male detection, significant fitness benefits from such avoidance strategies would be predicted. Methodology/Principal Findings: Among four Littorina species, one lives at very much higher densities and has a longer mating season than the other three species. Using video records of snail behaviour in a laboratory arena we show that males of the low-density species discriminate among male and female mucous trails, trailing females for copulations. In the high-density species, however, males fail to discriminate between male and female trails, not because males are unable to identify female trails (which we show using heterospecific females), but because females do not, as the other species, add a gender-specific cue to their trail. Conclusions/Significance: We conclude that there is likely a sexual conflict over mating frequency in the high-densit

Genotype–phenotype correlation in contactin-associated protein-like 2 (CNTNAP-2) developmental disorder

Contactin-associated protein-like 2 (CNTNAP2) gene encodes for CASPR2, a presynaptic type 1 transmembrane protein, involved in cell–cell adhesion and synaptic interactions. Biallelic CNTNAP2 loss has been associated with “Pitt-Hopkins-like syndrome-1” (MIM#610042), while the pathogenic role of heterozygous variants remains controversial. We report 22 novel patients harboring mono- (n = 2) and bi-allelic (n = 20) CNTNAP2 variants and carried out a literature review to characterize the genotype–phenotype correlation. Patients (M:F 14:8) were aged between 3 and 19 years and affected by global developmental delay (GDD) (n = 21), moderate to profound intellectual disability (n = 17) and epilepsy (n = 21). Seizures mainly started in the first two years of life (median 22.5 months). Antiseizure medications were successful in controlling the seizures in about two-thirds of the patients. Autism spectrum disorder (ASD) and/or other neuropsychiatric comorbidities were present in nine patients (40.9%). Nonspecific midline brain anomalies were noted in most patients while focal signal abnormalities in the temporal lobes were noted in three subjects. Genotype–phenotype correlation was performed by also including 50 previously published patients (15 mono- and 35 bi-allelic variants). Overall, GDD (p < 0.0001), epilepsy (p < 0.0001), hyporeflexia (p = 0.012), ASD (p = 0.009), language impairment (p = 0.020) and severe cognitive impairment (p = 0.031) were significantly associated with the presence of biallelic versus monoallelic variants. We have defined the main features associated with biallelic CNTNAP2 variants, as severe cognitive impairment, epilepsy and behavioral abnormalities. We propose CASPR2-deficiency neurodevelopmental disorder as an exclusively recessive disease while the contribution of heterozygous variants is less likely to follow an autosomal dominant inheritance pattern

Life-history traits in four species of <i>Littorina</i>.

<p>Densities for <i>L. saxatilis</i> are indicated for the Swedish cliff ecotype (E). Data on reproductive seasons are from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0012005#pone.0012005-Reid1" target="_blank">[13]</a>, and numbers of eggs per year are from unpublished studies by KJ except for <i>L. littorea</i> where data are from Buschbaum & Reise <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0012005#pone.0012005-Buschbaum1" target="_blank">[37]</a>. Snail density estimates are from typical habitats of each species taken into account the surface area of the substratum, see text for details.</p

<i>Littorina saxatilis</i> males tracking males and females of their own or an other species (<i>L. fabalis</i>).

<p>(A) Distances that males of <i>L. saxatilis</i> followed males and females of their own species. (B) Distances that males of <i>L. saxatilis</i> followed males and females of <i>L. fabalis</i>. Experimental conditions and statistical tests as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0012005#pone-0012005-g001" target="_blank">Figure 1</a>.</p

Polarity of trail-following in male <i>Littorina</i>.

<p>Polarity of trail-following in male <i>Littorina</i>.</p