A comparative study of heavy metal concentrations in the clam Corbicula javanica and surface sediments collected from clean and polluted sites of Langat River, Selangor.

Previously, anthropogenic activities in Langat River had been reported to have negative impact on the riverine water quality (Sarmani, 1989; Azrina et al., 2006). This involved a wide range of macrobenthic invertebrates. Since the Langat River serves as one of the major sources of drinking water for the citizens of Kuala Lumpur (Sarmani, 1989), pollution due to domestic and industrial wastes from rubber mills which can be found at the south of Hulu Langat town and palm oil refineries close to Banting (Sarmani, 1989). This has raised concern on the need to conduct continuous monitoring of hazardous materials at Langat River, particularly heavy metals. There are several monitoring approaches to quantify and investigate heavy metal contamination, such as, by analyses of concentrations in water, sediments and biota. Sarmani (1989) had reported arsenic concentrations was slightly higher than that of natural level, particularly water of downstream of the river. In respect of sediment analysis, Shazili et al. (2006) have reported sediments of Langat River were confronted with Pb and Zn. In current study, the quantification of heavy metal concentrations in the surface sediments and the measurement of metal concentrations in indigenous biomonitor clam Corbicula javanica were conducted. The metal concentrations found in the biomonitor have high relevant from ecotoxicological point of view because they reflect the metal bioavailabilities to the biomonitor from the ecosystem (Rainbow, 1995)

A vortex model for transport in the polar stratosphere

A semi-empirical model based on a Gaussian vorticity distribution was developed for determining eddy diffusivity and wind transport distributions in the polar stratosphere. The model uses as input data pressure surface heights measured at periods of the year when the stratospheric polar vortex exhibits nearly circular patterns around the pole. The components of the polar wind velocities that result from a Prandtl eddy viscosity distribution are found to be in general agreement with those obtained by other investigators

Modelling the Mechanical Behaviour of a Pharmaceutical Tablet Using PDEs.

yesDetailed design of pharmaceutical tablets is essential nowadays in order to produce robust tablets with tailor-made properties. Compressibility and compactibility are the main compaction properties involved in the design and development of solid dosage forms. The data obtained from measured forces and displacements of the punch are normally analysed using the Heckel model to assess the mechanical behaviour of pharmaceutical powders. In this paper, we present a technique for shape modelling of pharmaceutical tablets based on the PDE method. We extended the formulation of the PDE method to a higher dimensional space in order to generate a solid tablet and a cuboid mesh is created to represent the tablet¿s components. We also modelled the displacement components of a compressed PDE- based representation of a tablet by utilising the solution of the axisymmetric boundary value problem for a finite cylinder subject to a uniform axial load. The experimental data and the results obtained from the developed model are shown in Heckel plots and a good agreement is found between both.Available in full text since 5th Feb 2013 following the publisher's embargo period

Using Machine Learning Approaches to Explore Non-Cognitive Variables Influencing Reading Proficiency in English Among Filipino Learners FINAL REPORT

Filipino students ranked last in reading proficiency among all countries/territories in the PISA 2018, with only 19% meeting the minimum (Level 2) standard. It is imperative to understand the range of factors contributing to low reading proficiency, specifically variables that can be the target of interventions to help the students with poor reading proficiency. We used machine learning approaches, specifically binary classification methods, to identify the variables that best predict low (Level 1b and lower) vs. higher (Level 1a or better) reading proficiency using the Philippine PISA data from a nationally representative sample of 15-year-old students. Several binary classification methods were applied, and the best classification model was derived using support vector machines (SVM), with 81.2% average test accuracy. The 20 variables with the highest impact in the model were identified and interpreted using the socioecological perspective of development and learning. These variables included students’ home-related resources and socioeconomic constraints, learning motivation and mindsets, reading classroom experiences with teachers, reading self-beliefs, attitudes and experiences, and social experiences in the school environment. The results were discussed with reference to the need for a system perspective to address poor proficiency that requires interconnected interventions that go beyond the students’ reading classroom

On the asymptotic and practical complexity of solving bivariate systems over the reals

This paper is concerned with exact real solving of well-constrained, bivariate polynomial systems. The main problem is to isolate all common real roots in rational rectangles, and to determine their intersection multiplicities. We present three algorithms and analyze their asymptotic bit complexity, obtaining a bound of \sOB(N^{14}) for the purely projection-based method, and \sOB(N^{12}) for two subresultant-based methods: this notation ignores polylogarithmic factors, where $N$ bounds the degree and the bitsize of the polynomials. The previous record bound was \sOB(N^{14}). Our main tool is signed subresultant sequences. We exploit recent advances on the complexity of univariate root isolation, and extend them to sign evaluation of bivariate polynomials over two algebraic numbers, and real root counting for polynomials over an extension field. Our algorithms apply to the problem of simultaneous inequalities; they also compute the topology of real plane algebraic curves in \sOB(N^{12}), whereas the previous bound was \sOB(N^{14}). All algorithms have been implemented in MAPLE, in conjunction with numeric filtering. We compare them against FGB/RS, system solvers from SYNAPS, and MAPLE libraries INSULATE and TOP, which compute curve topology. Our software is among the most robust, and its runtimes are comparable, or within a small constant factor, with respect to the C/C++ libraries. Key words: real solving, polynomial systems, complexity, MAPLE softwareComment: 17 pages, 4 algorithms, 1 table, and 1 figure with 2 sub-figure

The role of insight, social rank, mindfulness and self-compassion in depression following first episode psychosis

Gaining awareness of psychosis (i.e., insight) is linked to depression, particularly in the post-acute phase of psychosis. Informed by social rank theory, we examined whether the insight–depression relationship is explained by reduced social rank related to psychosis and whether self-compassion (including uncompassionate self-responding [UCS] and compassionate self-responding [CSR]) and mindfulness buffered the relationship between social rank and depression in individuals with first episode psychosis during the post-acute phase. Participants were 145 young people (Mage = 20.81; female = 66) with first episode psychosis approaching discharge from an early psychosis intervention centre. Questionnaires and interviews assessed insight, depressive symptoms, perceived social rank, self-compassion, mindfulness and illness severity. Results showed that insight was not significantly associated to depression and thus no mediation analysis was conducted. However, lower perceived social rank was related to higher depression, and this relationship was moderated by self-compassion and, more specifically, UCS. Mindfulness was related to depression but had no moderating effect on social rank and depression. Results supported previous findings that depressive symptoms are common during the post-acute phase. The role of insight in depression for this sample is unclear and may be less important during the post-acute phase than previously considered. Supporting social rank theory, the results suggest that low perceived social rank contributes to depression, and reducing UCS may ameliorate this effect. UCS, social rank and possibly mindfulness may be valuable intervention targets for depression intervention and prevention efforts in the recovery of psychosis

Determination of contamination and bioavailabilities of heavy metals (Cu, Cd, Zn, Pb and Ni) in the Sri Serdang Urban Lake by using guppy fish Poecilia reticulata

The guppy fish, Poecilia reticulata and the lake surface sediments were collected from the Serdang Lake in August 2005. Both the fish and the sediment samples were analyzed for Cu, Cd, Pb, Zn and Ni. The ranges of metal concentrations (μg g-1 dry weight) in the fish were 0.160-11.1 μg g-1 for Cu; 64.6-174 μg g-1 for Zn; 0.400-4.03 μg g-1 for Cd; 3.27-12.1 μg g-1 for Ni and 19.5-50.9 μg g-1 for Pb. In the sediment, the ranges of metal concentrations were 1.97-62.1 μg g-1 for Cu; 31.6-274 μg g-1 for Zn; 1.92-3.17 μg g-1 for Cd; 60.2-94.8 μg g-1 for Ni and 3.23-42.1 μg g-1 for Pb. It was found that the concentrations of Zn was the highest found in both fish and sediment samples, followed by Pb, Cu, Ni and Cd. The similar pattern of heavy metal occurrence was found in the fish and in the sediment, indicated that the fish could be used as a potential biomonitor for metal contamination in the freshwater ecosystem. Since P. reticulata are widely distributed in lakes and in almost all of the urban drainage, this fish species is a very potential biomonitor of heavy metal bioavailabilites in the polluted freshwater ecosystem of Malaysia

Determining how polymer-bubble interactions impact algal separation using the novel "Posi"-dissolved air flotation process

The novel dissolved air flotation (DAF) process that uses hydrophobically-modified polymers (HMPs) to generate positively charged bubbles (PosiDAF) has been shown to separate negatively charged algal cells without the need for coagulation-flocculation. Previous research has been limited to HMPs of poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) and, while they were effective at bench-scale, performance at pilot-scale was better using commercial poly(N,N-diallyl-N,N-dimethylammonium chloride) (PDADMAC). Hence, the aim of this research was to compare the effectiveness of PDADMAC modified with aliphatic and aromatic moieties in comparison to previously tested PDMAEMA HMPs in respect to algal cell separation and minimisation of effluent polymer concentration, as well as defining the underlying polymer-bubble interaction mechanisms. Polymer-bubble adhesion properties were measured using atomic force microscopy (AFM) while polymer concentration was monitored via zeta potential and, where possible, assays using fluorescence spectroscopy. Both PDADMAC functionalised with a fluorinated aromatic group (PDADMAC-BCF) and PDMAEMA modified with 1-bromodecane respectively, gave effective cell separation, while the treated effluent zeta potential values at maximum cell removal were lower than the other polymers trialled. The effluent polymer concentration when using PDADMAC-BCF was four times lower in comparison to another aromatically modified PDADMAC polymer. AFM studies indicated that, in contrast to the PDMAEMA-based polymers, the PDADMAC-based polymers did not adsorb closely to the bubble surface. The different polymer-bubble interactions indicate that separation mechanisms will also vary, potentially leading to differences in process effectiveness when explored at pilot scale

High Prudent diet factor score predicts lower relapse hazard in early multiple sclerosis

Background: Dietary patterns and their association with subsequent clinical course have not been well studied in early multiple sclerosis (MS). Objectives: To describe dietary patterns in people in 5 years following first clinical demyelination and assess associations with MS conversion and relapse. Methods: This study included baseline food frequency questionnaire dietary intake (entry to the Ausimmune Study) and 5-year follow-up; iterated principal factor analysis was applied. MS conversion and relapse risks were assessed by Cox proportional hazards models, adjusted for age, sex, study site, education, body mass index (BMI), smoking and omega-3 supplement use. Results: In cases with a first clinical diagnosis of central nervous system (CNS) demyelination, we identified three major dietary patterns, 'Prudent', 'High-Vegetable' and 'Mixed', explaining 43%, 37% and 24% of diet variance in dietary intake, respectively. Fruits, vegetables, fish, wholegrains and nuts loaded highly on the Prudent pattern, starchy vegetables and legumes on the High-Vegetable pattern, and meats and alcohol on the Mixed pattern. Diet factor scores were not associated with MS conversion risk. Those with baseline Prudent scores above the median had significantly lower relapse risk (adjusted hazard ratio = 0.54, 95% confidence interval (CI) 0.37, 0.81) with some evidence of a plateau effect. Conclusion: Prudent diet factor score above the median was prospectively associated with lower relapse risk in the 5 years following the first clinical demyelinating event

Stable Isotopes Approach to Infer the Feeding Habit and Trophic Position of Freshwater Fishes in Tropical Lakes

A study was conducted on the stable isotope variation of muscle tissues from selected freshwater fish species from Temenggor Lake and Chenderoh Lake, Perak, Malaysia from December 2014 to March 2015. The objective is to assess the stable isotopes of δ13C to identify the carbon sources and δ15N of fish species from Temenggor and Chenderoh Lake, Perak, Malaysia to infer the trophic position of these fishes. Four types of fish species were analyzed by using stable isotope approach which were Hampala barb (Hampala macrolepidota), Oxygaster cyprinus (Oxygaster anomalura), Peacock Bass (Cichla ocellaris) and Nile Tilapia (Oreochromis niloticus). Stable isotopes of δ13C and δ15N were analysed using an elemental analyser Thermo Finnigan Flash EA 2000 connected to Finningan DELTA V AVANTAGE plus isotope ratio mass spectrometry by a ConFlo II interface. The δ13C values from both lakes implies a C3 phytoplankton as reported from the literature. Based on δ15N values of fish species, O. anomalura occupies the highest trophic level in Temenggor Lake, reflecting its carnivorous feeding habit despite its small size while C. ocellaris was the highest in Chenderoh Lake, implying its predatory behaviour. Further analysis should be carried out to incorporate primary producers and consumers to elucidate the food web in the tropical lake ecosystem. This study provides a reference record for conducting stable isotopes in the food web of tropical lake ecosystem for better management and deeper understanding of the ecosystem functioning