Current assessment practices in schools in Malta and Gozo - a research project

• As part of its action plan, the Educational Assessment Focus Group carried out a survey on current assessment practices in schools in Malta and Gozo. Two complementary research tools were used to collect the data for this project. All Heads of Schools were invited to be interviewed and fill in a questionnaire. In total, 62% of the schools (119 / 191) collaborated in the interview process and 52% (98 / 191) returned the completed questionnaire. • In the year 2002, only 24.5% of the schools that participated in the survey (24 / 98) said that they have an assessment policy document in their school. The survey responses indicated that that several approaches have been used in formulating this document. • The majority of schools that responded to the questionnaire, with the exception of three, answered the question on current assessment practices. Overall, the data showthat the range of urrent assessment practices in schools is wide and varied. These practices are generally formative or summative and relate to ways of collectinginformation and ways of recording and reporting information to students and parents/guardians. Annual tests and examinations, half yearly tests and examinations, the correction of class and home work and classroom-based tests are the most common ways of collection information whereas the most common practices related to record keeping are recording information to pass on to parents/guardians, filling in the cumulative record cards and using merit cards and certificates of merit. Overall, record keeping is not popular in Maltese schools. • The schools reported that a variety of modes are used to give students feedback about their progress. It is common practice for teachers in Malta to mark and/or correct student work, whether the work in question is class work, home work or tests. It is also common for teachers to writecomments on the students’ exercise books and test papers. This form of individualised feedback is sometimes used in conjunction with, replaces or is replaced by short interactions between the teacher and the student. Other common practices are class discussion once the work is returned to the students and sending reports home after the half yearly and annual tests and examinations. All school representatives reported that most of the feedback about children’s progress is given to parents/guardians orally during Parents’ Day/s. All schools hold at least one Parents’ Day but it is quite common for schools to have two such days. • The data relating to successful assessment practices indicated that current practices are still very much embedded within a traditional culture of examinations and testing and assessment is used for summative purposes. The majority of the participants felt that examinations and tests were still the most effective and reliable method of collecting information regarding student progress. Despite this emphasis on traditional assessment practices, however, most of the participants did agree that it was also important to make use of formative assessment in order to help and support the learning process. • The schools’ current concerns regarding assessment practices range from practical issues regarding time constraints, inadequate recording systems and the need for staff training to more philosophical concerns such as the impact of examinations on students and parents, to issues regarding the reliability and validity of our assessment practices and the pressing need for levels of achievement and assessment criteria to ensure fair and valid means of recording and reporting on student progress. • The participants focused on a limited range of innovative practices that they intend to implement in their schools in the near future. All of the innovations form part of the new national minimum curriculum.peer-reviewe

Transforming triangulations on non planar-surfaces

We consider whether any two triangulations of a polygon or a point set on a non-planar surface with a given metric can be transformed into each other by a sequence of edge flips. The answer is negative in general with some remarkable exceptions, such as polygons on the cylinder, and on the flat torus, and certain configurations of points on the cylinder.Comment: 19 pages, 17 figures. This version has been accepted in the SIAM Journal on Discrete Mathematics. Keywords: Graph of triangulations, triangulations on surfaces, triangulations of polygons, edge fli

Steady-state fluctuations of a genetic feedback loop:an exact solution

Genetic feedback loops in cells break detailed balance and involve bimolecular reactions; hence exact solutions revealing the nature of the stochastic fluctuations in these loops are lacking. We here consider the master equation for a gene regulatory feedback loop: a gene produces protein which then binds to the promoter of the same gene and regulates its expression. The protein degrades in its free and bound forms. This network breaks detailed balance and involves a single bimolecular reaction step. We provide an exact solution of the steady-state master equation for arbitrary values of the parameters, and present simplified solutions for a number of special cases. The full parametric dependence of the analytical non-equilibrium steady-state probability distribution is verified by direct numerical solution of the master equations. For the case where the degradation rate of bound and free protein is the same, our solution is at variance with a previous claim of an exact solution (Hornos et al, Phys. Rev. E {\bf 72}, 051907 (2005) and subsequent studies). We show explicitly that this is due to an unphysical formulation of the underlying master equation in those studies.Comment: 31 pages, 3 figures. Accepted for publication in the Journal of Chemical Physics (2012

Stochastic theory of large-scale enzyme-reaction networks: Finite copy number corrections to rate equation models

Chemical reactions inside cells occur in compartment volumes in the range of atto- to femtolitres. Physiological concentrations realized in such small volumes imply low copy numbers of interacting molecules with the consequence of considerable fluctuations in the concentrations. In contrast, rate equation models are based on the implicit assumption of infinitely large numbers of interacting molecules, or equivalently, that reactions occur in infinite volumes at constant macroscopic concentrations. In this article we compute the finite-volume corrections (or equivalently the finite copy number corrections) to the solutions of the rate equations for chemical reaction networks composed of arbitrarily large numbers of enzyme-catalyzed reactions which are confined inside a small sub-cellular compartment. This is achieved by applying a mesoscopic version of the quasi-steady state assumption to the exact Fokker-Planck equation associated with the Poisson Representation of the chemical master equation. The procedure yields impressively simple and compact expressions for the finite-volume corrections. We prove that the predictions of the rate equations will always underestimate the actual steady-state substrate concentrations for an enzyme-reaction network confined in a small volume. In particular we show that the finite-volume corrections increase with decreasing sub-cellular volume, decreasing Michaelis-Menten constants and increasing enzyme saturation. The magnitude of the corrections depends sensitively on the topology of the network. The predictions of the theory are shown to be in excellent agreement with stochastic simulations for two types of networks typically associated with protein methylation and metabolism.Comment: 13 pages, 4 figures; published in The Journal of Chemical Physic

Accurate discretization of advection-diffusion equations

We present an exact mathematical transformation which converts a wide class of advection-diffusion equations into a form allowing simple and direct spatial discretization in all dimensions, and thus the construction of accurate and more efficient numerical algorithms. These discretized forms can also be viewed as master equations which provides an alternative mesoscopic interpretation of advection-diffusion processes in terms of diffusion with spatially varying hopping rates

Liquid filled canyons on Titan

In May 2013 the Cassini RADAR altimeter observed channels in Vid Flumina, a drainage network connected to Titan’s second largest hydrocarbon sea, Ligeia Mare. Analysis of these altimeter echoes shows that the channels are located in deep (up to ~570 m), steep-sided, canyons and have strong specular surface reflections that indicate they are currently liquid filled. Elevations of the liquid in these channels are at the same level as Ligeia Mare to within a vertical precision of about 0.7 m, consistent with the interpretation of drowned river valleys. Specular reflections are also observed in lower order tributaries elevated above the level of Ligeia Mare, consistent with drainage feeding into the main channel system

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

Optimisation of abiraterone based non-steroidal lead molecules

Management of castration resistant prostate cancer is limited by androgen receptor reactivation resulting in loss of remission. A recent study indicated that abiraterone exhibits antagonist activity towards the androgen receptor in addition to CYP17A1 inhibition.Metribolone has demonstrable in vitro and in vivo high affinity for the AR thus it was established as a benchmark against which the affinity of abiraterone and de novo designed non-steroidal molecules could be compared. Binding affinities of abiraterone manually superimposed onto the steroid scaffold of metribolone (pKd 7.16) and abiraterone that was allowed limited rotation (pKd 7.23)were comparable to metribolone (pKd 7.44).The de novo study generated an 8 analogue molecular series with affinities ranging between 5.26 and 7.23. This study yielded sufficient analogues that may be proposed for further molecular optimisation to yield innovative non-steroidal high affinity molecules with superior side-effect profiles for the management of prostate cancer.peer-reviewe

Monitoring of a quasi-stationary eddy in the Bay of Biscay by means of satellite, in situ and model results

The presence of a quasi-stationary anticyclonic eddy within the southeastern Bay of Biscay (centred around 44°30′N-4°W) has been reported on various occasions in the bibliography. The analysis made in this study for the period 2003–2010, by using in situ and remote sensing measurements and model results shows that this mesoscale coherent structure is present almost every year from the end of winter-beginning of spring, to the beginning of fall. During this period it remains in an area limited to the east by the Landes Plateau, to the west by Le Danois Bank and Torrelavega canyon and to the northwest by the Jovellanos seamount. All the observations and analysis made in this contribution, suggest that this structure is generated between Capbreton and Torrelavega canyons. Detailed monitoring from in situ and remote sensing data of an anticyclonic quasi-stationary eddy, in 2008, shows the origin of this structure from a warm water current located around 43°42′N-3°30′W in mid-January. This coherent structure is monitored until August around the same area, where it has a marked influence on the Sea Level Anomaly, Sea Surface Temperature and surface Chlorophyll-a concentration. An eddy tracking method, applied to the outputs of a numerical model, shows that the model is able to reproduce this type of eddy, with similar 2D characteristics and lifetimes to that suggested by the observations and previous works. This is the case, for instance, of the simulated MAY04 eddy, which was generated in May 2004 around Torrelavega canyon and remained quasi-stationary in the area for 4 months. The diameter of this eddy ranged from 40 to 60 km, its azimuthal velocity was less than 20 cm s−1, its vertical extension reached 3000–3500 m depth during April and May and it was observed to interact with other coherent structures