A general multivariate latent growth model with applications in student careers Data warehouses

The evaluation of the formative process in the University system has been assuming an ever increasing importance in the European countries. Within this context the analysis of student performance and capabilities plays a fundamental role. In this work we propose a multivariate latent growth model for studying the performances of a cohort of students of the University of Bologna. The model proposed is innovative since it is composed by: (1) multivariate growth models that allow to capture the different dynamics of student performance indicators over time and (2) a factor model that allows to measure the general latent student capability. The flexibility of the model proposed allows its applications in several fields such as socio-economic settings in which personal behaviours are studied by using panel data.Comment: 20 page

Evolution of level density step structures from 56,57-Fe to 96,97-Mo

Level densities have been extracted from primary gamma spectra for 56,57-Fe and 96,97-Mo nuclei using (3-He,alpha gamma) and (3-He,3-He') reactions on 57-Fe and 97-Mo targets. The level density curves reveal step structures above the pairing gap due to the breaking of nucleon Cooper pairs. The location of the step structures in energy and their shapes arise from the interplay between single-particle energies and seniority-conserving and seniority-non-conserving interactions.Comment: 9 pages, including 5 figure

Assessing the effect of Liquid Petroleum Gas ( LPG ) car conversion system in petrol car by local Artisans in Ghana.

Conversion of petrol to LPG fuelled vehicles is often carried out by mechanics who are not professionally trained in Ghana. Therefore this study was carried out to assess the effects of conversion systems of petrol cars to LPG by local artisans.  Data was collected through three techniques namely observation (i.e. Fifteen LPG installation garages), survey (112 questionnaires) and interviews with LPG installation expert from Don Bosco Training Centre in Tema, and local workshop owners. A total of 112 questionnaires were administered to LPG installation mechanics and drivers sampled randomly from the study area. The study clearly shows that most of the apprenticeship trainings were carried out by unprofessionally trained LPG installers under trees and in open garages which were not standard automobile repair workshops. Most of the vehicles do not have any safety detectors installed in them. According to the drivers, it was very difficult to detect leakage unless they smell the odour of the gas. Keywords: LPG, LPG conversion, Vehicles, Local artisans, Ghan

Optical Line Width Broadening Mechanisms at the 10 kHz Level in Eu3+:Y2O3 Nanoparticles

We identify the physical mechanisms responsible for the optical homogeneous broadening in Eu3+:Y2O3 nanoparticles to determine whether rare-earth crystals can be miniaturized to volumes less than λ3 whilst preserving their appeal for quantum technology hardware. By studying how the homogeneous line width depends on temperature, applied magnetic field, and measurement time scale the dominant broadening interactions for various temperature ranges above 3 K were characterized. Below 3 K the homogeneous line width is dominated by an interaction not observed in bulk crystal studies. These measurements demonstrate that broadening due to size-dependent phonon interactions is not a significant contributor to the homogeneous line width, which contrasts previous studies in rare-earth ion nanocrystals. Importantly, the results provide strong evidence that for the 400 nm diameter nanoparticles under study the minimum line width achieved (45±1 kHz at 1.3 K) is not fundamentally limited. In addition, we highlight that the expected broadening caused by electric field fluctuations arising from surface charges is comparable to the observed broadening. Under the assumption that such Stark broadening is a significant contribution to the homogeneous line width, several strategies for reducing this line width to below 10 kHz are discussed. Furthermore, it is demonstrated that the Eu3+ hyperfine state lifetime is sufficiently long to preserve spectral features for timescales up to 1 s. These results allow integrated rare-earth ion quantum optics to be pursued at a sub-micron scale and hence, open up directions for greater scaling of rare-earth quantum technology

Detection of functional PTEN lipid phosphatase protein and enzyme activity in squamous cell carcinomas of the head andeck, despite loss of heterozygosity at this locus

The human tumour suppressor gene PTEN located at 10q23 is mutated in a variety of tumour types particularly metastatic cases and in the germline of some individuals with Cowdens cancer predisposition syndrome. We have assessed the status of PTEN and associated pathways in cell lines derived from 19 squamous cell carcinomas of the head and neck. Loss of heterozygosity is evident at, or close to the PTEN gene in 5 cases, however there were no mutations in the remaining alleles. Furthermore by Western analysis PTEN protein levels are normal in all of these SCC-HN tumours and cell lines. To assess the possibility that PTEN may be inactivated by another mechanism, we characterized lipid phosphatase levels and from a specific PIP3 biochemical assay it is clear that PTEN is functionally active in all 19 human SCCs. Our data strongly suggest the possibility that a tumour suppressor gene associated with development of SCC-HN, other than PTEN, is located in this chromosomal region. This gene does not appear to be MXI-1, which has been implicated in some other human tumour types. PTEN is an important negative regulator of PI3Kinase, of which subunit alpha is frequently amplified in SCC-HN. To examine the possibility that PI3K is upregulated by amplification in this tumour set we assessed the phosphorylation status of Akt, a downstream target of PI3K. In all cases there is no detectable increase in Akt phosphorylation. Therefore there is no detectable defect in the PI3K pathway in SCC-HN suggesting that the reason for 3q26.3 over-representation may be due to genes other than PI3K110α. © 2001 Cancer Research Campaign http://www.bjcancer.co

Photoactivation experiment on 197Au and its implications for the dipole strength in heavy nuclei

The 197Au(gamma,n) reaction is used as an activation standard for photodisintegration studies on astrophysically relevant nuclei. At the bremsstrahlung facility of the superconducting electron accelerator ELBE (Electron Linear accelerator of high Brilliance and low Emittance) of Forschungszentrum Dresden-Rossendorf, photoactivation measurements on 197Au have been performed with bremsstrahlung endpoint energies from 8.0 to 15.5 MeV. The measured activation yield is compared with previous experiments as well as with calculations using Hauser-Feshbach statistical models. It is shown that the experimental data are best described by a two-Lorentzian parametrization with taking the axial deformation of 197Au into account. The experimental 197Au(gamma,n) reaction yield measured at ELBE via the photoactivation method is found to be consistent with previous experimental data using photon scattering or neutron detection methods.Comment: 9 page

Secondary metabolite profiling of the model legume Lotus japonicus during its symbiotic interaction with Mesorhizobium loti

Plant secondary metabolites, particularly flavonoids, are key components in the early stages of nitrogen-fixing symbiosis. Despite their importance, the endogenous secondary metabolites involved in symbiosis have not yet been identified in the model legume Lotus japonicus. We therefore determined changes in the secondary metabolic profile of Lotus japonicus roots in response to its symbiont. Analysis of the root secondary metabolite profiles 1 week after inoculation with Mesorhizobium loti revealed quantitative changes in the level of 14 phenolic peaks when compared with non-inoculated control plants. These changes affected compounds from most phenolic classes, possibly resulting from interconversion between classes since the total phenolic level remained constant. In addition, the use of 2 M. loti strains differing only in their capacity to synthesise Nod factor revealed that, although Nod factor signalling induced accumulation of a specific subset of 4 phenolic peaks, most changes were induced in response to both rhizobial strains.NR was supported by a Training Network funded by the European Training Network EU-RTN-LOTUS-HPRN-CT-2000-00086. KJW was supported by core funding from the Biotechnology and Biological Science Research Council (BBSRC), UK.Peer Reviewe

Fragmentation and systematics of the Pygmy Dipole Resonance in the stable N=82 isotones

The low-lying electric dipole (E1) strength in the semi-magic nucleus 136Xe has been measured which finalizes the systematic survey to investigate the so-called pygmy dipole resonance (PDR) in all stable even N=82 isotones with the method of nuclear resonance fluorescence using real photons in the entrance channel. In all cases, a fragmented resonance-like structure of E1 strength is observed in the energy region 5 MeV to 8 MeV. An analysis of the fragmentation of the strength reveals that the degree of fragmentation decreases towards the proton-deficient isotones while the total integrated strength increases indicating a dependence of the total strength on the neutron-to-proton ratio. The experimental results are compared to microscopic calculations within the quasi-particle phonon model (QPM). The calculation includes complex configurations of up to three phonons and is able to reproduce also the fragmentation of the E1 strength which allows to draw conclusions on the damping of the PDR. Calculations and experimental data are in good agreement in the degree of fragmentation and also in the integrated strength if the sensitivity limit of the experiments is taken into account

Driver Preference for Automatic or Manual Transmission Systems for Vehicles: A Case Study in Ghana

Systems in vehicles are being modified due to current technological trends. One of the commonest modified systems in vehicles was the transmission system. This study presented    views of drivers on preference for automatic or manual transmission vehicles in Ghana.   In all, data was collected from 1260 drivers selected randomly through survey, in-depth interviews and six focus group discussions. The study indicated that manual transmission vehicles were more in Ghana with the automatic now gaining relative patronage. However, automatic transmission vehicles were preferred by females than males. The first three factors that determined preference for automatic transmission were shifting quality, easy to use and power (engine) performance. However, for manual transmission vehicles repairability (easily reparable), reliability and better fuel economy were the first three factors that determined driver’s choice for such vehicles. The results further showed that most respondents believed that manual transmission vehicles had strong advantages over the automatic ones. The study concludes that more people prefer manual transmission vehicles than the automatic ones although the automatic ones are now gaining popularity. Key words:Automatic transmission, Manual Transmission, Vehicles, Preference, Ghan

Masses and Phase Structure in the Ginzburg-Landau Model

We study numerically the phase structure of the Ginzburg-Landau model, with particular emphasis on mass measurements. There is no local gauge invariant order parameter, but we find that there is a phase transition characterized by a vanishing photon mass. For type I superconductors the transition is of 1st order. For type II 1st order is excluded by susceptibility analysis, but the photon correlation length suggests 2nd order critical behaviour with \nu ~ 1/2. The scalar mass, in contrast, does not show clear critical behaviour in the type II regime for V \to \infty, contrary to the conventional picture.Comment: 16 pages, 6 figures. More data gathered, allowing more definite conclusion