Clustering Complex Zeros of Triangular Systems of Polynomials

This paper gives the first algorithm for finding a set of natural $\epsilon$-clusters of complex zeros of a triangular system of polynomials within a given polybox in $\mathbb{C}^n$, for any given $\epsilon>0$. Our algorithm is based on a recent near-optimal algorithm of Becker et al (2016) for clustering the complex roots of a univariate polynomial where the coefficients are represented by number oracles. Our algorithm is numeric, certified and based on subdivision. We implemented it and compared it with two well-known homotopy solvers on various triangular systems. Our solver always gives correct answers, is often faster than the homotopy solver that often gives correct answers, and sometimes faster than the one that gives sometimes correct results.Comment: Research report V6: description of the main algorithm update

Wrist flexion rehabilitation device using arm mbed microcontroller for post-stroke patient

Rehabilitation is a process of recovery of an individual from disabling or functionally limiting condition, whether temporary or irreversible, participates to regain maximal function, independence, and restoration [1]. The purpose of rehabilitation is to prevent and slow down the loss of function of the body, improve and restore the function, compensation for the lost function, and maintenance of the current function

Factors Affecting the Credit Spreads Behaviour of USD Malaysian Bonds

This paper addresses empirical analysis of Malaysian credit spreads in a number of directions. Firstly, the investigation of explanatory power of macroeconomic or market variables to the changes in the spreads. Secondly, use of daily data rather than data sampled to match typical macroeconomic data release. Third, a focused study on the market behaviour of bonds issued from a rapidly emerging market. Fourth, the inclusion of semi-parametric measures to better capture the behaviour of the credit spreads. This study finds that changes in credit spread of Malaysian bonds are only receptive to certain macroeconomic factors. Also changes in credit spreads are negatively correlated with the interest factor but this study could not find convincing evidence to support the argument of a negative relationship with the asset factor.Credit spreads, Emerging markets, Malaysia

Distribution of Heavy Metals in the Different Parts of Cerithidea Obtusa and the Relationships between Metal Distribution and Allometric Parameters of the Snail

The intertidal gastropod, Cerithidea obtusa were obtained from Bako and Sematan (Sarawak) and Deralik (Perak). Besides the shell, the snails were dissected into five different soft tissues. The soft tissues and the shell were then analysed for heavy metals. It was found that the highest concentrations of Cu (112 - 178 μg/g dw) and Zn (117 - 161 μg/g dw) were found in the tentacle; the highest concentrations of Cd (4.41 - 5.37 μg/g dw), Pb (53.2 - 63.8 μg/g dw) and Ni (26.1 - 27.9 μg/g dw) were found in the shell. On the other hand, the highest Fe concentrations (910 - 2921 μg/g dw) were found in the operculum. The Spearman's correlation coefficient and multiple stepwise linear regression also revealed that the allometric parameters can influence the distribution of heavy metals in some of the different parts. From the present findings indicated that the heavy metals accumulated by the C. obtusa from the environment might affect its physical growth, which was shown by the negative correlations found between the metals in the different parts with the allometric parameters

Variations of electrical conductivity between upstream and downstream of Langat River, Malaysia: its significance as a single indicator of water quality deterioration

This paper investigated the potential of using a single chemical parameter namely electrical conductivity (EC) as an indicator of water quality pollution in relation to dissolved oxygen (DO) and suspended solids (SS) which are two of the parameters included in the calculation of Water Quality Index (WQI) in Malaysia based on current scenario. In this study, nine periodic samplings at eight sampling sites along a tropical river which included the polluted downstream and the unpolluted upstream of the Langat River, were conducted between March 1998 and January 1999. The consistent results for the nine month samples (negative and significant correlation between EC vs. DO, and positive and significant correlation between EC vs. SS), indicated that EC could be potentially used as a single chemical parameter to indicate the water quality of tropical rivers such as the Langat River of Malaysia. It is also recommended that EC should be included in the revised WQI in Malaysia in future, in order to better reflect the mineral-related pollution/composition and of the water samples

Assessment of Green-Lipped Mussel Perna Viridis (Linnaeus) As a Biomonitoring Agent of Cadmium, Copper, Mercury, Lead and Zinc for the West Coast of Peninsular Malaysia

Sediment samples (46 sites) and green-lipped mussels Perna viridis (L.) (19 sites) from the west coast of Peninsular Malaysia were sampled between 1998 and 2001 and were analyzed for Cd, Cu, Hg, Pb and Zn. The mean levels of the metals in the west coast (offshore: intertidal) sediments were 0.75 ± 0.06 : 0.86 ± 0.11 µg/g dry weight (dw) for Cd, 4.27 ± 0.36 : 29.22 ± 8.84 µg/g dw for Cu, 38.87 ± 2.93 : 60.10 ± 9.47 µg/g dw for Hg, 17.36 ± 0.99 : 23.32 ± 3.39 µg/g dw for Pb and 37.22 ± 2.01 : 84.64 ± 12.62 µg/g dw for Zn. The metal levels in the soft tissues (ST) of P. viridis were found to be 0.25-1.35 µg/g dw for Cd, 6.31-20.21 µg/g dw for Cu, 20.00-152.00 µg/g dw for Hg, 1.27-8.76 ug/g dw for Pb and 53.82-135.50 µg/g dw for Zn. All these metal levels were relatively low in comparison with previously published regional data. In general, the metal levels were higher in the intertidal sediment than in the offshore sediment. Geochemical studies in the sediments revealed that about 58.6 : 57.7% for Cd, 53.3 : 46.3% for Cll, 72.6 : 54.3% for Pb and 34.5 : 48.7% for Zn, in the offshore and intertidal sediments, respectively, were most likely due to anthropogenic sources. Localized elevations of heavy metals in a few locations indicated that the offshore and intertidal areas of the west coast of Peninsular Malaysia were likely to have received anthropogenic metals. By using the protein level a1lozyme approach, the genetic differentiation among the different geographical populations of this species fell within the range for conspecific populations. Since P. viridis populations are sedentary, widely distributed in the west coastal area of Peninsular Malaysia and have low genetic differentiation, the species generally is a good biomonitoring agent for heavy metals in the area. The mussel P. viridis collected from the field also showed that the metal concentrations in its total ST were positively and significantly (P< 0.05) correlated with Cd, eu and Pb in the environment as represented by the sediment samples. The suitability of P. viridis as a biomonitoring agent for heavy metals was experimentally studied. The results of the laboratory experiments showed that the ST of P. viridis was readily capable of accumulating heavy metals especially Cd, Pb and Hg to elevated levels. Depuration studies also showed that the metal levels in different STs were significantly (P< 0.05) correlated with those of the seawater. By using endpoints mortality, filtration rate (FR) and condition index (CI), P. viridis was found to be a sensitive but tolerant organism to Cd, Cu, Pb and Zn. The byssus (BYS) of P. viridis was found to be a sensitive biomonitoring tool for Zn whereas its total shell was a good biomonitoring material for Cd and Pb. Allozyme polymorphism of P. viridis was found to be a potential biomarker for metal contamination. Simple indicators (aerial exposure and shell deformities of P. viridis) for heavy metal pollution were also identified

The gill of Perna viridis as a major route entry for Pb : a laboratory study.

The distribution and levels of Cd, Pb and Zn were determined in the gill and remaining soft tissues of Perna viridis under laboratory conditions based on sublethal concentrations of metals (Cd: 1.210 mg/L; Pb: 1.645 mg/L; Zn: 2.950 mg/L) for four days exposure, followed by four days elimination. The results showed that the concentrations of Pb were higher in the gill than those in the remaining soft tissues during exposure and elimination periods while Zn levels were only higher during exposure period. However, Cd levels were lower in the gills than in the remaining soft tissues during exposure and elimination periods These laboratory results indicated that gills are the major entry route for the Pb, and to a lesser extent for Zn but unlikely for Cd since the Cd in the gill was lower than in the remaining soft tissues. The present findings indicated that different routes of uptake for Cd, Pb and Zn in the different tissues of P. viridis regardless of the fact that gill having a large surface area with mucus sheets which could facilitated the metal uptake. Other organs than gill could be another route of uptake for Zn and Cd in P. viridis

Distributions of Cu and Zn in the shell lipped part periostracum and soft tissues of perna viridis: the potential of periostracum as a biomonitoring material for Cu contamination

Periostracum is the outer shell layer composes mainly of organic materials. In the present study, the green-lipped mussel Perna viridis was used to investigate the distributions of Cu and Zn in the periostracum and soft tissues of the P. viridis which were sampled from 17 geographical sites [23 populations] along the coastal waters of Peninsular Malaysia. The concentrations of Cu in the periostracum and the soft tissues of P. viridis were 7.41- 42.63 mg/g dry weight and 3.49-31.1 mg/g dry weight, respectively. Meanwhile, the concentrations of Zn in the periostracum and soft tissues of P. viridis were 4.90-39.79 mg/g dry weight and 65.75-144.9 mg/g dry weight, respectively. The ratios of the metals in periostracum to soft tissues were 0.73-3.99 mg/g for Cu and 0.05-0.36 mg/g for Zn. These ratios indicated that the concentrations of Cu in the periostracum were generally greater than those in the soft tissues while the concentrations of Zn were generally higher in the soft tissues than those in the periostracum. The higher Cu levels in the soft tissues compared to that in the periostracum (Fig. 2) and the relatively close relationships of Cu between periostracum and sediment indicated that the periostracum was a good biomonitoring material for Cu, but periostracum was not a good biomonitoring material for Zn because it did not reflect the environmental contamination as reflected in the low correlation between the periostracum and sediment