Perception of pre-service teachers on the use of blended learning techniques in Nwafor Orizu College of Education, Nsugbe, Anambra State

Pre-service teachers face several challenges as they strive to achieve excellence in their chosen field. Not only must they prove they master their subject matter, but they must also show competence in classroom management, methodology, and assessment. These can be achieved during their pre-service training. This study examined perceptions of pre-service teachers on Blended Learning Techniques (BLT). The purpose of the study was to identify, examine and analyse the perceptions of pre-service teachers in Nwafor Orizu college of Education Nsugbe, Anambra state on Blended learning techniques. The population for the study was one hundred and forty (140), 200 level pre-service teachers and the sample for the study consisted of 70, 200 level pre-service teachers randomly selected using simply random sample. Two sub-scale questionnaires were used for data collection. The data were analysised using percentage, frequency table and simple statistical mean to find the average responses of the study. Means that fall below 2.50 were rejected. The results of the study showed that pre-service teachers had positive opinions about blended learning techniques and there are challenges in the implementations. It was recommended among others that, different models of blended learning techniques should be adopted according to the courses instead of one typical model for all courses. Also lecturers should be motivated and there should be stable and constant power supply. There should be free internet access for a successful implementation.Keywords: Blended learning techniques, face to face learning, web based learning, pre-service teacher, and interne

Comparison of decision methods to initiate fungicide applications against cercospora blight of carrot

Un modèle prévisionnel a été comparé, en 1991 et 1992, à d'autres méthodes pour son efficacité à déterminer le début des applications de fongicides utilisés pour lutter contre la brûlure cercosporéenne de la carotte, causée par le Cercospora carotae. Le premier traitement fongicide était appliqué lorsque : 1) les plants avaient atteint 15 cm de hauteur (méthode conventionnelle); 2) les feuilles intermédiaires de 50 % des plants présentaient des symptômes (méthode du 50 % d'incidence); 3) lorsque la valeur cumulative d'équivalence d'infection (CE) avait atteint 14 (méthode de prévision avec la valeur CIE = 14); 4) lorsque la valeur CIE avait atteint 18 (méthode de prévision avec la valeur CIE = 18). Pour toutes les méthodes, les applications subséquentes de fongicides ont été faites aux 10 jours lorsqu'il n'y avait pas de pluie, et aux 7 jours en présence de pluie. Les valeurs CIE ont été calculées en fonction de la durée d'humectation du feuillage et de la température durant cette période, tout en tenant compte des périodes d'humidité élevée et d'interruptions des périodes d'humectation du feuillage, et étaient cumulatives depuis l'émergence des plants. Pour les méthodes avec prévision, que ce soit pour une valeur CIE de 14 ou de 18, aucune perte de rendement n'a été observée et moins de traitements ont été nécessaires comparativement à la méthode conventionnelle et à celle du 50 % d'incidence. Dans une autre étude, les valeurs CIE ont été comparées aux pourcentages de champs qui avaient atteint des niveaux d'incidence de 50, 80 et 100% afin d'établir les seuils de risque léger (11 < CIE < 15) et de risque élevé (16 < CIE < 20). Seulement 3% des champs avaient déjà atteint l'incidence de 50 % lorsqu'une valeur CIE a atteint le seuil préconisé pour un risque faible et, 19 % des champs, une incidence de 80% pour un risque élevé.In 1991 and 1992, two thresholds of a forecasting model were compared with two other decision methods for effectiveness in timing the first fungicide application against Cercospora blight of carrot induced by Cercospora carotae. The first fungicide application was made when : 1) the plants reached 15 cm in height (conventional method); 2) the intermediate (middle) leaves of 50% of the plants were diseased (50% disease incidence threshold method); 3) the cumulative infection equivalence (CE) was 14 (forecasting model CE 14); and 4) the CE was 18 (forecasting model CE 18). In all four treatments, subsequent applications of fungicide were made at 10-d intervals when there was no rain, and at 7-d intervals when there was rain. The CE was calculated based on duration of leaf wetness and temperature during the wet period, corrected for high humidity and interrupted wet periods, and was cumulative starting at crop emergence. For thresholds of CE 14 and CE 18, no yield losses were observed and the total number of fungicide applications needed was lower compared to conventional and 50% disease incidence threshold methods. In a separate study, the CE thresholds were related to the percentage of commercial fields that reached disease incidence thresholds of 50, 80 and 100% to establish low risk (CE 11-15) and high risk (CE 16-20) thresholds. The forecasting of low and high risk CE thresholds were too late for 3 and 19% of the commercial fields because those fields had more than 50 and 80% of the plants diseased, respectively

Taxonomic significance of the abaxial lemma surface in southern African members of Helictotrichon (Poaceae)

BACKGROUND : Helictotrichon (excluding Amphibromus, Avenula, Helictochloa and Tricholemma), a genus of temperate C3 grasses, is represented by 14 species in southern Africa. Members of the genus are difficult to identify at species level on the basis of macromorphology alone. OBJECTIVES : The primary objective of this study was to investigate the usefulness of the micromorphology of the lemma surface for differentiating amongst the southern African members of Helictotrichon. METHOD : Lemma surfaces were studied with scanning electron microscopy (SEM). Lemmas were obtained from herbarium specimens housed in the National Herbarium, Pretoria (PRE). These were mounted on aluminium stubs using double-sided adhesive tape, sputter-coated with gold, and photographs were taken using a J840 scanning electron microscope. RESULTS : Based on whether the lemma surface is smooth, papillate, scaberulous, scabrid or a combination of these, five groups of species are distinguished. All species, except Helictotrichon barbatum which has a smooth lemma surface, have small prickles (scaberulous). Helictotrichon leoninum, Helictotrichon quinquesetum and Helictotrichon rogerellisii have only small prickles, whilst Helictotrichon dodii, Helictotrichon hirtulum, Helictotrichon namaquense and Helictotrichon roggeveldense have, in addition, medium to large prickles (scabrid). Helictotrichon capense, Helictotrichon longifolium, Helictotrichon longum and Helictotrichon turgidulum have a combination of small prickles and papillae whilst Helictotrichon galpinii and Helictotrichon natalense have a combination of all three. A key to the groups and photos of the different types of surfaces are provided. CONCLUSION : The micromorphology of the lemma surface was shown to be of considerable taxonomic significance and to be extremely useful for differentiating amongst species.South African National Biodiversity Institutehttp://www.abcjournal.orgam2016Plant Scienc

Taxonomic significance of epidermal structure in southern African members of Helictotrichon

Helictotrichon Besser ex Schult. & Schult.f. (excluding Avenula (Dumort.) Dumort. and Amphibromus Nees) is a genus of temperate C3 grasses with about 40 species (Gibbs Russell et al. 1990; Mabberley 2008). The genus is most diverse in the temperate regions of the northern hemisphere, especially in Europe, from where it extends southwards along the African mountains (Afromontane Region). This paper deals only with those species occurring in southern Africa, a secondary centre of diversity for the genus.http://www.sanbi.org/products/publications/bothalia.htmam201

An Anatomy of Price Dynamics in Illiquid Markets: Analysis and Evidence from Local Housing Markets

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73407/1/j.1080-8620.2004.00082.x.pd

Geometric Integration of Hamiltonian Systems Perturbed by Rayleigh Damping

Explicit and semi-explicit geometric integration schemes for dissipative perturbations of Hamiltonian systems are analyzed. The dissipation is characterized by a small parameter $\epsilon$, and the schemes under study preserve the symplectic structure in the case $\epsilon=0$. In the case $0<\epsilon\ll 1$ the energy dissipation rate is shown to be asymptotically correct by backward error analysis. Theoretical results on monotone decrease of the modified Hamiltonian function for small enough step sizes are given. Further, an analysis proving near conservation of relative equilibria for small enough step sizes is conducted. Numerical examples, verifying the analyses, are given for a planar pendulum and an elastic 3--D pendulum. The results are superior in comparison with a conventional explicit Runge-Kutta method of the same order

Ecological restoration across the Mediterranean Basin as viewed by practitioners

Restoration efforts in the Mediterranean Basin have been changing from a silvicultural to an ecological restoration approach. Yet, to what extent the projects are guided by ecological restoration principles remains largely unknown. To analyse this issue, we built an on-line survey addressed to restoration practitioners. We analysed 36 restoration projects, mostly from drylands (86%). The projects used mainly soil from local sources. The need to comply with legislation was more important as a restoration motive for European Union (EU) than for non-EU countries, while public opinion and health had a greater importance in the latter. Non-EU countries relied more on non-native plant species than EU countries, thus deviating from ecological restoration guidelines. Nursery-grown plants used were mostly of local or regional provenance, whilst seeds were mostly of national provenance. Unexpected restoration results (e.g. inadequate biodiversity) were reported for 50% of the projects and restoration success was never evaluated in 22%. Long term evaluation (> 6 years) was only performed in 31% of cases, and based primarily on plant diversity and cover. The use of non-native species and species of exogenous provenances may: i) entail the loss of local genetic and functional trait diversity, critical to cope with drought, particularly under the predicted climate change scenarios, and ii) lead to unexpected competition with native species and/or negatively impact local biotic interactions. Absent or inappropriate monitoring may prevent the understanding of restoration trajectories, precluding adaptive management strategies, often crucial to create functional ecosystems able to provide ecosystem services. The overview of ecological restoration projects in the Mediterranean Basin revealed high variability among practices and highlighted the need for improved scientific assistance and information exchange, greater use of native species of local provenance, and more long-term monitoring and evaluation, including functional and ecosystem services' indicators, to improve and spread the practice of ecological restoration

Nonequilibrium wetting

When a nonequilibrium growing interface in the presence of a wall is considered a nonequilibrium wetting transition may take place. This transition can be studied trough Langevin equations or discrete growth models. In the first case, the Kardar-Parisi-Zhang equation, which defines a very robust universality class for nonequilibrium moving interfaces, with a soft-wall potential is considered. While in the second, microscopic models, in the corresponding universality class, with evaporation and deposition of particles in the presence of hard-wall are studied. Equilibrium wetting is related to a particular case of the problem, it corresponds to the Edwards-Wilkinson equation with a potential in the continuum approach or to the fulfillment of detailed balance in the microscopic models. In this review we present the analytical and numerical methods used to investigate the problem and the very rich behavior that is observed with them.Comment: Review, 36 pages, 16 figure

Lightning NOx, a key chemistry–climate interaction: impacts of future climate change and consequences for tropospheric oxidising capacity

Lightning is one of the major natural sources of NOx in the atmosphere. A suite of time slice experiments using a stratosphere-resolving configuration of the Unified Model (UM), containing the United Kingdom Chemistry and Aerosols sub-model (UKCA), has been performed to investigate the impact of climate change on emissions of NOx from lightning (LNOx) and to highlight its critical impacts on photochemical ozone production and the oxidising capacity of the troposphere. Two Representative Concentration Pathway (RCP) scenarios (RCP4.5 and RCP8.5) are explored. LNOx is simulated to increase in a year-2100 climate by 33% (RCP4.5) and 78% (RCP8.5), primarily as a result of increases in the depth of convection. The total tropospheric chemical odd oxygen production (P(Ox)) increases linearly with increases in total LNOx and consequently, tropospheric ozone burdens of 29±4 Tg(O3) (RCP4.5) and 46±4 Tg(O3) (RCP8.5) are calculated here. By prescribing a uniform surface boundary concentration for methane in these simulations, methane-driven feedbacks are essentially neglected. A simple estimate of the contribution of the feedback reduces the increase in ozone burden to 24 and 33 Tg(O3), respectively. We thus show that, through changes in LNOx, the effects of climate change counteract the simulated mitigation of the ozone burden, which results from reductions in ozone precursor emissions as part of air quality controls projected in the RCP scenarios. Without the driver of increased LNOx, our simulations suggest that the net effect of climate change would be to lower free tropospheric ozone. In addition, we identify large climate-change-induced enhancements in the concentration of the hydroxyl radical (OH) in the tropical upper troposphere (UT), particularly over the Maritime Continent, primarily as a consequence of greater LNOx. The OH enhancement in the tropics increases oxidation of both methane (with feedbacks onto chemistry and climate) and very short-lived substances (VSLS) (with implications for stratospheric ozone depletion). We emphasise that it is important to improve our understanding of LNOx in order to gain confidence in model projections of composition change under future climate

Combined constraints on modified Chaplygin gas model from cosmological observed data: Markov Chain Monte Carlo approach

We use the Markov Chain Monte Carlo method to investigate a global constraints on the modified Chaplygin gas (MCG) model as the unification of dark matter and dark energy from the latest observational data: the Union2 dataset of type supernovae Ia (SNIa), the observational Hubble data (OHD), the cluster X-ray gas mass fraction, the baryon acoustic oscillation (BAO), and the cosmic microwave background (CMB) data. In a flat universe, the constraint results for MCG model are, $\Omega_{b}h^{2}=0.02263^{+0.00184}_{-0.00162}$ ($1\sigma$) $^{+0.00213}_{-0.00195}$ $(2\sigma)$, $B_{s}=0.7788^{+0.0736}_{-0.0723}$ ($1\sigma$) $^{+0.0918}_{-0.0904}$ $(2\sigma)$, $\alpha=0.1079^{+0.3397}_{-0.2539}$ ($1\sigma$) $^{+0.4678}_{-0.2911}$ $(2\sigma)$, $B=0.00189^{+0.00583}_{-0.00756}$ ($1\sigma$) $^{+0.00660}_{-0.00915}$ $(2\sigma)$, and $H_{0}=70.711^{+4.188}_{-3.142}$ ($1\sigma$) $^{+5.281}_{-4.149}$ $(2\sigma)$.Comment: 12 pages, 1figur