Novice programmers and the problem description effect.

It is often debated whether a problem presented in a straightforward minimalist fashion is better, or worse, for learning than the same problem presented with a real-life or concrete context. The presentation, contextualization, or problem description has been well studied over several decades in disciplines such as mathematics education and psychology; however, little has been published in the field of computing education. In psychology it has been found that not only the presence of context, but the type of context can have dramatic results on problem success. In mathematics education it has been demonstrated that there are non-mathematical factors in problem presentation that can affect success in solving the problem and learning. The contextual background of a problem can also impact cognitive load, which should be considered when evaluating the effects of context. Further, it has been found that regarding cognitive load, computer science has unique characteristics compared to other disciplines, with the consequence that results from other disciplines may not apply to computer science, thus requiring investigation within computer science. This paper presents a multi-national, multi-institutional study of the effects of problem contextualization on novice programmer success in a typical CS1 exercise

First outbreak with chimeric swine enteric coronavirus (SeCoV) on pig farms in Slovakia – lessons to learn

This report describes the first disease outbreak caused by chimeric swine enteric coronavirus (SeCoV) on two pig farms in Slovakia in early 2015. The infection was introduced by import of two breeding boars which were placed in provisional quarantine in a unit not strictly separated from other healthy pigs in the same building. Subsequently, loss of appetite and diarrhoea were observed in both boars during the first three days in the isolation unit. The infection gradually spread to the farrowing area and throughout the farm in two weeks and later to another nearby farm. Yellow watery diarrhoea accompanied by dehydration and death was observed in piglets with a mortality ranging from 30 to 35%. In the absence of an available vaccine, the pregnant sows were dosed by mouth with a 10% suspension prepared from the intestine and faeces of infected piglets in warm water. Three weeks after dosing, new litters of piglets were born which remained healthy with no development of diarrhoea

Cytopathic bovine viral diarrhea viruses (BVDV): emerging pestiviruses doomed to extinction

Bovine viral diarrhea virus (BVDV), a Flaviviridae pestivirus, is arguably one of the most widespread cattle pathogens worldwide. Each of its two genotypes has two biotypes, non-cytopathic (ncp) and cytopathic (cp). Only the ncp biotype of BVDV may establish persistent infection in the fetus when infecting a dam early in gestation, a time point which predates maturity of the adaptive immune system. Such fetuses may develop and be born healthy but remain infected for life. Due to this early initiation of fetal infection and to the expression of interferon antagonistic proteins, persistently infected (PI) animals remain immunotolerant to the infecting viral strain. Although only accounting for some 1% of all animals in regions where BVDV is endemic, PI animals ensure the viral persistence in the host population. These animals may, however, develop the fatal mucosal disease, which is characterized by widespread lesions in the gastrointestinal tract. Cp BVD virus, in addition to the persisting ncp biotype, can be isolated from such animals. The cp viruses are characterized by unrestrained genome replication, and their emergence from the persisting ncp ones is due to mutations that are unique in each virus analyzed. They include recombinations with host cell mRNA, gene translocations and duplications, and point mutations. Cytopathic BVD viruses fail to establish chains of infection and are unable to cause persistent infection. Hence, these viruses illustrate a case of “viral emergence to extinction” – irrelevant for BVDV evolution, but fatal for the PI host

No evidence of enteric viral involvement in the new neonatal porcine diarrhoea syndrome in Danish pigs

The aim of this study was to investigate whether the syndrome New Neonatal Porcine Diarrhoea Syndrome (NNPDS) is associated with a viral aetiology. Four well-managed herds experiencing neonatal diarrhoea and suspected to be affected by NNPDS were included in a case-control set up. A total of 989 piglets were clinically examined on a daily basis. Samples from diarrhoeic and non-diarrhoeic piglets at the age of three to seven days were selected for extensive virological examination using specific real time polymerase chain reactions (qPCRs) and general virus detection methods. A total of 91.7% of the animals tested positive by reverse transcription qPCR (RT-qPCR) for porcine kobuvirus 1 (PKV-1) while 9% and 3% were found to be positive for rotavirus A and porcine teschovirus (PTV), respectively. The overall prevalence of porcine astrovirus (PAstV) was 75% with 69.8% of the PAstV positive pigs infected with PAstV type 3. No animals tested positive for rotavirus C, coronavirus (TGEV, PEDV and PRCV), sapovirus, enterovirus, parechovirus, saffoldvirus, cosavirus, klassevirus or porcine circovirus type 2 (PCV2). Microarray analyses performed on a total of 18 animals were all negative, as were eight animals examined by Transmission Electron Microscopy (TEM). Using Next Generation de novo sequencing (de novo NGS) on pools of samples from case animals within all herds, PKV-1 was detected in four herds and rotavirus A, rotavirus C and PTV were detected in one herd each. Our detailed analyses of piglets from NNPDS-affected herds demonstrated that viruses did not pose a significant contribution to NNPDS. However, further investigations are needed to investigate if a systemic virus infection plays a role in the pathogenesis of NNPDS

Cryogenic cave carbonates from the Cold Wind Cave, Nízke Tatry Mountains, Slovakia: Extending the age range of cryogenic cave carbonate formation to the Saalian

Cold Wind Cave, located at elevations ranging between 1,600 and 1,700 m a. s. l. in the main range of the Nízke Tatry Mountains(Slovakia), is linked in origin with the adjacent Dead Bats Cave. Together, these caves form a major cave system located within anarrow tectonic slice of Triassic sediments. Both caves have undergone complex multiphase development. A system of sub-horizontalcave levels characterized by large, tunnel-like corridors was formed during the Tertiary, when elevation differences surroundingthe cave were less pronounced than today. The central part of the Nízke Tatry Mountains, together with the cave systems, wasuplifted during the Neogene and Lower Pleistocene, which changed the drainage pattern of the area completely. The formation ofnumerous steep-sloped vadose channels and widespread cave roof frost shattering characterized cave development throughout theQuaternary.In the Cold Wind Cave, extensive accumulations of loose, morphologically variable crystal aggregates of secondary cave carbonateranging in size between less than 1 mm to about 35 mm was found on the surface of fallen limestone blocks. Based on the C andO stable isotope compositions of the carbonate (δ13C: 0.72 to 6.34 ‰, δ18O: –22.61 to –13.68 ‰ V-PDB) and the negative relationbetween δ13C and δ18O, the carbonate crystal aggregates are interpreted as being cryogenic cave carbonate (CCC). Publishedmodels suggest the formation of CCC in slowly freezing water pools, probably on the surface of cave ice, most probably duringtransitions from stadials to interstadials. Though the formation of these carbonates is likely one of the youngest events in thesequence of formation of cave sediments of the studied caves, the 230Th/234U ages of three samples (79.7±2.3, 104.0±2.9, and180.0±6.3 ka) are the oldest so far obtained for CCC in Central Europe. This is the first description of CCC formation in one caveduring two glacial periods (Saalian and Weichselian)

Effect of Applied Current Density of Plasma Electrolytic Oxidation Process on Corrosion Resistance of AZ31 Magnesium Alloy

Impact of applied current density during the plasma electrolytic oxidation (PEO) process on corrosion resistance of AZ31 magnesium alloy was studied. The PEO coatings were prepared using four different current densities with values of 0.025 A/cm2, 0.05 A/cm2, 0.1 A/cm2 and 0.15 A/cm2 in electrolyte consisting of 10 g/l Na 3PO4.12H2O and 1 g/l KOH. Morphology and chemical composition of the coatings was examined using the scanning electron microscopy and EDS analysis respectively. Electrochemical characteristics of ground and coated samples were measured by means of electrochemical impedance spectroscopy (EIS) in 0.1M NaCl solution. Obtained data in form of Nyquist diagrams were analysed by equivalent circuit method. Results of experiments showed that value of applied current density had significant effect on protective performance of the PEO coatings prepared on AZ31 magnesium alloy surface

Effect of Phosphating Temperature on Surface Properties of Manganese Phosphate Coating on HSLA Steel

A phosphating process modified for a high-strength low-alloy (HSLA) steel was performed at various temperatures and influence on the surface properties of the Domex steel covered by manganese phosphate (MnP) was investigated by electrochemical corrosion tests supported by a photo documentation performed by the SEM. Corrosion measurements were performed in 0.1M NaCl solution at 22±2 °C using electrochemical impedance spectroscopy and potentio-dynamic polarisation in order to obtain thermodynamic and kinetic corrosion characteristics and individual elements of equivalent circuits. It is that a temperature of the phosphating process has a very significant effect on protection properties of the created manganese phosphate coating on the Domex steel and needs to be strictly monitored. According to results of corrosion testing and surface morphology observations, the optimal temperature for the phosphating process on the tested Domex steel was chosen