Selling space and time : the case of sejjieh dekorattiv

Sometime during the late 1980's, the weathered stones from dismantled or collapsed dry-stone walls started being gathered, and their outer surfaces were sawn away in laminae about an inch thick. Such laminae, weathered and rugged on one side, freshly cut and smooth on the other, were then glued side by side to the facades of newly-built houses. The neatly cut, white limestone ashlar masonry in which these facades, like most buildings in Malta, had been raised, was concealed beneath the collage of darkened and irregularly shaped slices of rubble. At first glance, the areas treated in this way had been transformed into a rubble wall. Ethnographic research has been conducted in San Gwann, a suburban village and Rabat, a small town. Several streets were explored in these localities in order to obtain some understanding of the distribution of sejjieh dekorattiv throughout the village or town, paying close attention to the role it plays in the context of particular facades. Fifteen informal interviews were carried out with a number of home-owners, aimed at eliciting their perceptions of sejjieh dekorattiv. This article is the first result of an ongoing research project. Important issues, such as the trends which emerge from the overall distribution of sejjieh dekorattiv throughout Malta as a whole have not as yet been tackled. The observations which follow must not be seen as definitive. They should rather be seen as an attempt to initiate discussion and investigation of this issue.peer-reviewe

‘It’s been worth the effort’: Primary school teachers learning to teach mathematics remotely during the pandemic

We draw on Spring 2021 findings from a 2019-2022 study of impact and use of a ‘mastery’-oriented primary (ages 4-11) mathematics resource, ‘Power Maths’, in England. The study follows 40 classes of primary children and their teachers, in 20 schools, over two years. Our findings span the return into school from the early 2021 lockdown period, comparing and contrasting teachers’ approaches across the two pandemic-related lockdown periods, the first in March-June 2020. Most teachers developed a significantly wider range of, and confidence in, remote learning practices. They came to expect more, and active, new learning, rather than aiming just to consolidate prior knowledge. Many developed active selection of the most appropriate topics for home learning, substantially increased ‘live’ teaching, and found ways to more proactively monitor work. Despite this, some challenges persisted: providing effective formative assessment and insecure knowledge of parental support and of gaps in children’s learning

Mind the gap: Mathematics teaching and learning in Power Maths primary schools in a pandemic autumn

We report Autumn 2020 findings from a 2019-2021 study of impact and use of a ‘mastery’-oriented primary (ages 4-11) mathematics resource, ‘Power Maths’. The study follows 40 classes of primary children and their teachers, in 20 schools, over two years. Following earlier pandemic evidence, more recent data show schools and teachers responding to Autumn ‘mathematics recovery’ challenges in very different ways, with a range of creativity, of solution-focus, and of alignment with the Power Maths-promoted ‘mastery’ approaches, although more complex mathematical processes commonly remained marginalised. Teachers reported that new classroom guidelines severely restricted ‘carpet’ and group work and use of manipulatives. They pervasively referenced identification and addressing of gaps in children’s prior learning. While most teachers expressed concern about the continuing impact on mathematical development, and reduction in confidence, they reported children usually still responding positively to mathematical opportunities to learn, and confidence slowly returning

Cultivation and anaerobic digestion of Scenedesmus spp. grown in a pilot-scale open raceway

Digestibility of a micro-algal mixture was evaluated by mesophilic anaerobic digestion in continuously-stirred tank reactors. The culture consisted primarily of Scenedesmus spp. continuously cultivated over a 6-month period in a 100 m2 raceway reactor instrumented to record pH, dissolved oxygen and temperature. The raceway received supplementary carbon in the form of flue gas from a diesel boiler (10% CO2) injected into a 1-m deep sump to control pH in the range 7.8–8.0. Dilution was optimised to biomass productivity and gave values of 10–15 and 20–25 g total suspended solids (TSS) m? 2 day? 1 in winter (December–February) and spring (April–May), respectively. The culture for the anaerobic digestion trial was harvested in February by centrifugation to give an algal paste containing 4.3% volatile solids (VS). Semi-continuous digestion at organic loading rates of 2.00, 2.75 and 3.50 g VS l? 1 day? 1 gave volumetric biogas productions of ~ 0.66, ~ 0.83 and ~ 0.99 l l? 1 day? 1, respectively. Specific methane yield ranged from 0.13 to 0.14 l CH4 g? 1 VSadded with biogas methane content ~ 62%. Overall the digestion process was stable, but only ~ 30% VS destruction was achieved indicating low biodegradability, due to the short retention times and the recalcitrant nature of this type of biomas

A stochastic model of corneal epithelium maintenance and recovery following perturbation

Various biological studies suggest that the corneal epithelium is maintained by active stem cells located in the limbus, the so-called limbal epithelial stem cell hypothesis. While numerous mathematical models have been developed to describe corneal epithelium wound healing, only a few have explored the process of corneal epithelium homeostasis. In this paper we present a purposefully simple stochastic mathematical model based on a chemical master equation approach, with the aim of clarifying the main factors involved in the maintenance process. Model analysis provides a set of constraints on the numbers of stem cells, division rates, and the number of division cycles required to maintain a healthy corneal epithelium. In addition, our stochastic analysis reveals noise reduction as the epithelium approaches its homeostatic state, indicating robustness to noise. Finally, recovery is analysed in the context of perturbation scenarios

Photobioreactor Design and Fluid Dynamics

Photobioreactor design is a subject of great relevance for the attainment of a sustained development in modern technology,and has also considerable interest from the basic scientific and technologic point of view.The aim of the present review paper is presenting and comparing some of the recent attempts by the authors of modelling photosynthesis in reactors.A short inspection of the kinetic models proposed for photobioreactor design is done,and some examples of the integration of such kinetic models and bioreactor fluid dynamics in the modelling of photobioreactors are presented

A novel mechanism for generating auxetic behaviour in reticulated foams : missing rib foam model

Foams have previously been fabricated with a negative Poisson's ratio (termed auxetic foams). A novel model is proposed to explain this and to describe the strain-dependent Poisson's function behaviour of honeycomb and foam materials. The model is two-dimensional and is based upon the observation of broken cell ribs in foams processed via the compression and heating technique usually employed to convert conventional foams to auxetic behaviour. The model has two forms: the “intact” form is a network of ribs with biaxial symmetry, and the “auxetic” form is a similar network but with a proportion of cell ribs removed. The model output is compared with that of an existing two-dimensional model and experimental data, and is found to be superior in predicting the Poisson's function and marginally better at predicting the stress–strain behaviour of the experimental data than the existing model, using realistic values for geometric parameters.peer-reviewe

The 5'-3' exoribonuclease Pacman (Xrn1) regulates expression of the heat shock protein Hsp67Bc and the microRNA miR-277-3p in Drosophila wing imaginal discs

Pacman/Xrn1 is a highly conserved exoribonuclease known to play a critical role in gene regulatory events such as control of mRNA stability, RNA interference and regulation via miRNAs. Although Pacman has been well studied in Drosophila tissue culture cells, the biologically relevant cellular pathways controlled by Pacman in natural tissues are unknown. This study shows that a hypomorphic mutation in pacman (pcm5) results in smaller wing imaginal discs. These tissues, found in the larva, are known to grow and differentiate to form wing and thorax structures in the adult fly. Using microarray analysis, followed by quantitative RT-PCR, we show that eight mRNAs were increased in level by >2 fold in the pcm5 mutant wing discs compared to the control. The levels of pre mRNAs were tested for five of these mRNAs; four did not increase in the pcm5 mutant, showing that they are regulated at the post-transcriptional level and therefore could be directly affected by Pacman. These transcripts include one that encodes the heat-shock protein Hsp67Bc, which is upregulated 11.9-fold at the post-transcriptional level and 2.3-fold at the protein level. One miRNA, miR-277-3p, is 5.6-fold downregulated at the post-transcriptional level in mutant discs, suggesting that Pacman affects its processing in this tissue. Together, these data show that a relatively small number of mRNAs and miRNAs substantially change in abundance in pacman mutant wing imaginal discs. Since Hsp67Bc is known to regulate autophagy and protein synthesis, it is possible that Pacman may control the growth of wing imaginal discs by regulating these processes

Synthesis, X-Ray Diffraction (XRD), Differential Thermal Analysis (DTA), and Scanning Electron Microscopy (SEM) of the Alloy (CuInTe2)1-x(NbTe)x with x=0.5

A polycrystalline ingot (30mm long, 10mm diameter) of the alloy (CuInTe2)1-x(NbTe)x with x=0.5 has been produced using the melt and anneal technique and characterized by X-Ray Diffraction (XRD), Diferential Thermal Analysys (DTA) and Scanning Electron Microscopy (SEM). From XRD results, and using Rietveld refinement method, the crystal structure has been obtained indicating than this alloy crystallizes in a chalcopyrite-like structure, space group  (Nº 112), unit cell parameters a = 6.1933(2) Å, c = 12.4293(2) Å, V = 476.75(2) Å3, figures of merit Rexp= 6.7%, Rp= 7.5%, Rwp= 7.3%, and S = 1.1. DTA measurements indicate three thermal transitions at 1028, 977 and 886 K in the heating cycle, and 1016, 900 and 848 K in the cooling. The transitions at 1028 and 1016 correspond to the melting and solidification point, respectively; the transitions at 977 and 900 K are of solid to liquid+solid type, whereas the transitions at 886 and 848 K correspond to order-disorder. The melting point is incongruent. In the diffraction pattern, traces of a secondary phase are observed; this phase has been identified using SEM technique as (CuIn)0.5NbTe2. DOI: http://dx.doi.org/10.17807/orbital.v14i1.167