Antagonistic Activities of Epiphytic Bacteria on Black Pod Disease of Cocoa

A study was conducted to determine the antagonistic activity of epiphytic bacteria isolated from cocoa pod surface on Phytophthora palmivora (Butler) Butler, the causal agent of black pod disease of cocoa. Out of 233 isolates of epiphytic bacteria obtained from non symptomatic and diseased cocoa pods, only were found to have antagonistic activities against the fungal pathogen when screened by the dual-culture method. Three isolates, (LKM/B/1, LKM/B/35, LKM/B/76c) were identified as Pseudomonas putida Biotype A, 2 isolates (LKM/B/5 and LKM/B/62b) were identified as Pseudomonas aeruginosa and one isolate each was identified as Pseudomonas spinosa (LKM/B/2), Burkholderia glidioli (LKM/B/4) and Burkholderia sp (LKM/B/6). Identification of the epiphytic bacteria was done using the BIOLOG® Identification System. Percentage inhibition of the radial growth (PIRG) of P. palmivora by the epiphytic bacteria ranged from 66.0% to 82.1%. All isolates of epiphytic bacteria showed optimum antagonistic activities at 300 C. pH has no influence on the antagonistic activities of the epiphytic bacteria. Detached pod studies showed that pods treated with the epiphytic bacteria retarded the growth of black pod lesion up to 12 days after inoculation. Isolate Burkholderia glidioli (LKM/B/4), Pseudomonas aeruginosa (LKM/B/5) and Pseudomonas putida Biotype A (LKM/B/76c) produced volatile substances that affect the growth of P. palmivora, while isolates LKM/B/1 and LKM/B/35 of Pseudomonas putida Biotype A and isolate LKM/B62b of Pseudomonas aeruginosa did not show the production of volatile substances. Isolate LKM/B/76c also produced diffusible metabolites that could significantly inhibit the growth of P. palmivora compared to other epiphytic bacteria especially isolate LKM/B/35 which showed good antagonistic through dual culture method. Microscopic observations of P. palmivora at the periphery of the inhibition zone indicated that all isolates of epiphytic bacteria inhibited P. palmivora by the process of cell wall degradation and growth retardation

Penentuan benefisiari bagi manfaat takaful berasaskan konsep ʻUmrā dan Ruqbā: penelitian dari sudut Fiqh

Kajian ini bertujuan untuk meneliti kesesuaian penggunaan konsep ʻumrā dan ruqbā sebagai asas kepada hibah bersyarat dalam menentukan benefisiari bagi manfaat takaful, sebagaimana yang terkandung di dalam Resolusi Syariah Dalam Kewangan Islam oleh Majlis Penasihat Syariah Bank Negara Malaysia dan Akta Perkhidmatan Kewangan Islam 2013. Persoalan yang ditimbulkan ialah: Adakah penggunaan konsep ruqbā sebagai asas kepada hibah bersyarat adalah tepat memandangkan status manfaat takaful sebagai harta milik peserta masih lagi samar? Melalui kaedah deskriptif dan analisis teks berasaskan pendekatan fiqh perbandingan mazhab, kajian ini meneliti realiti sebenar manfaat takaful dan memperhalusi perbahasan fuqaha mengenai ʻumrā dan ruqbā bagi menjelaskan kesesuaian penggunaan konsep ini sebagai asas pengurusan manfaat takaful menggunakan hibah bersyarat. Kajian ini mendapati bahawa sifat manfaat takaful yang belum wujud dan tidak mampu dimanfaatkan semasa hibah bersyarat dibuat menjadikan penggunaan ruqbā sebagai asas pertimbangan bagi hibah bersyarat ini tidak tepat. Ini berikutan, perbahasan fuqaha mengenai ʻumrā dan ruqbā adalah mengenai pemindahan hak milik yang dilakukan ke atas sesuatu harta yang telah wujud dan boleh dimanfaatkan semasa akad tersebut dibuat. Begitu juga, sebahagian fuqaha yang mengharuskan ʻumrā dan juga ruqbā serta menyatakan bahawa syarat yang terkandung di dalam keduanya sebagai harus, asas bagi pendapat mereka adalah; ʻumrā dan ruqbā merupakan akad yang menyebabkan pemindahan hak milik ke atas manfaat sesuatu harta seperti ʻāriyah, dan bukannya fizikal harta tersebut, yang membawa maksud bahawa harta yang dihibahkan telah wujud dan sedia untuk dimanfaatkan

Performance comparison of THF-NLFXLMS and VFXLMS algorithms for Hammerstein NANC

Recently, THF-NLFXLMS algorithm was developed to compensate the nonlinearity encountered in nonlinear active noise control systems. Despite similar performance, this algorithm is more advantageous than the Nonlinear Filtered-X Least Mean Square (NLFXLMS) due to the use of tangential hyperbolic function (THF) instead of scaled error function (SEF) which allows the degree of nonlinearity to be modeled. In addition, the computational complexity is relatively small compared to other direct nonlinear adaptive algorithm like the Volterra filter. In this paper, the performance of THF-NLFXLMS algorithm for Hammerstein secondary path structure is quantified and compared with NLFXLMS and the Volterra Filtered-x Least Mean Squares (VFXLMS) algorithm of similar computational complexity. The results show that the THF-NLFXLMS algorithm has similar performance as NLFXLMS algorithm and outperforms 2nd order VFXLMS algorithm

Performance comparison of LFXLMS, MOVFXLMS and THF-NLFXLMS algorithms for Hammerstein NANC

Filtered-X least mean square (FXLMS) algorithm is widely used in active noise control (ANC) systems when the secondary path is linear. However, the performance of FXLMS reduces when nonlinearity is present. Leaky FXLMS (LFXLMS) and minimum output variance FXLMS (MOVFXLMS) algorithms are effective in compensating the nonlinearity effects in nonlinear ANC (NANC). When using optimum leakage factors, these algorithms show close performance with benchmark nonlinear FXLMS (NLFXLMS) algorithm. In all three algorithms, the degree of nonlinearity must be known in advance and are usually assumed. In previous works, Tangential Hyperbolic Function NLFXLMS (THF-NLFXLMS) algorithm has been developed whereby the degree of nonlinearity is estimated using tangential hyperbolic function (THF). In this work, the performance of LFXLMS and MOVFXLMS based on optimum leakage factors calculated using the estimated degree of nonlinearity is compared with THF-NLFXLMS for Hammerstein structure. The results show that optimum MOVFXLMS performs similarly to optimum LFXLMS and THF-NLFXLMS

Design of self-tuning minimum effort active noise control with feedback inclusion architecture

This paper presents the development of a self-tuning controller design of minimum effort active noise control (ANC) for feedforward single-input single-output (SISO) architecture which includes the feedback acoustic path in the controller formulation. The controller design law is derived for suitable self-tuning implementation and the self-tuning controller is evaluated in a realistically constructed ANC simulation environment. The self-tuning controller design involves a two-stage identification process where the controller is replaced by a switch. This switch is closed and opened in sequence generating two transfer functions which are then used in constructing the controller specified by a minimum effort control law. The implementation requires an estimate of the secondary path transfer function which can be identified either online or offline. The controller design and implementation are evaluated in terms of the level of cancellation at the observer through simulation studies for various values of modified effort weighting parameter in the range ⩽0γ⩽1. It was found that the optimal controller designed using this technique which is constrained only by the accuracy of the two models identified using recursive least squares algorithm, yields good cancellation level

Analysis of geometry related constraints of minimum effort active noise control system

This paper presents an analysis of the geometry-related constraints of a single-input single output (SISO) minimum effort active noise control system with feedback inclusion architecture which includes the feedback path in the controller formulation. Realisation of this type of minimum effort controller imposes an infinite gain control (IGC) requirement for certain geometrical arrangements. In the investigation into these geometrical arrangements with fixed primary and secondary source locations, the IGC locus is found to be two circles occupied by the detector and observer respectively in three dimensions. Varying the minimum effort parameter term has the effect of moving these two circles closer or away from each other, hence varying their location and radii. As a result, the minimum effort parameter, apart from constraining the control signal has a potential of overcoming the IGC constraints for a fixed geometrical arrangement

Etiology and Control of Phytophthora Infestans (Mont.) De Bary in Malaysia

Phytophthora infestans (Mont.) De Bary is the causal agent of late blight disease of tomato, a major destructive disease of tomato in Cameron Highlands. The study undertaken was to isolate the pathogen on artificial media. The morphology and cultural characteristics were described. Disease development of P. infestans isolates on tomato was also studied. In-vivo sensitivity of the isolates towards metalaxyl was tested. Disease epidemiology studies were conducted during the two tomato planting periods in Cameron Highlands. Three isolates of P. infestans from Cameron High lands were isolated on Rye Grain Agar (RGrA), V-8 Juice Agar (V8JA) and Rye wholemeal Agar (RWMA) allamended with antibiotics with percentage recovery of 2%, 0.1% and 0.4% respectively. The P. infestans isolates were designated as PIB/01, PIH/01 and PIKR/01. No growth was observed on the two other media viz. Pea Agar and Difco LBA. Successful isolation were aided by baiting using potato tuber slices. Morphological studies of the P. infestans isolate showed that the mean zoosporangia size was 37.25um x 19.71um, mean L/B ratio of 1.91 and mean short pedicel length of 1.60um. Mean zoospores diameter measured 9.99 um. No chlamydospores was produced in culture

Loudspeaker nonlinearity compensation with inverse tangent hyperbolic function-based predistorter for active noise control

In active noise control (ANC), the performance of the filtered-x least mean squares (FXLMS) algorithm is degraded by the saturation of the loudspeaker in the secondary path. Predistortion is a linearization technique commonly used in signal processing applications to compensate for saturation nonlinearity. The design of the predistorter (PD) requires the use of direct measurement from the output of the nonlinear element. However, in ANC applications, direct measurement from the loudspeaker output is not available. Therefore, a conventional PD design approach cannot be directly applied. In this paper, a new PD-based compensation technique based on the inverse model of the loudspeaker nonlinearity is proposed. The PD is represented by an approximated memory-less inverse tangent hyperbolic function (ITHF). The approximated ITHF is scaled by a pre-identified parameter, which represents the loudspeaker nonlinearity strength. This parameter can be obtained by modelling the secondary path using a proposed block-oriented Hammerstein structure in which the nonlinear part is represented by a memory-less tangent hyperbolic function (THF). Simulation results show that using the proposed PD along with the FXLMS algorithm increase the noise reduction performance significantly

Effects of deficit irrigation on water productivity and maize yields in arid regions of Iran

Deficit irrigation in the Gavkhuni River Basin (GRB),Iran, is an effective method for alleviation of drought impacts on crop yields. Whilst it saves considerable amounts of water, it has little effect on crop yields. The effects of deficit irrigation on grain yield and yield components of maize were studied using two factors [namely, the variety at two levels (704 maize variety with 9354 kg ha -1 yield, and 647 maize variety with 8822 kg ha -1 yield) and irrigation at four levels (control, 100, 80, and 60% of water level use)] for three consecutive years. Significant differences (P≤0.05) were noticeable in grain yield, as well as depth and column of kernel among the irrigation treatments. In addition, the effects of cultivars on grain yield, 1000 kernel weight, number of kernel per ear row, number of kernel per column, and depth of kernels were insignificant. Nevertheless, the effects of irrigation treatments on 1000 kernel weight and number of kernel per ear row were not significant. Based on the results and considering the quantitative characteristics of the crop, it was established that for the deficit irrigating of maize, the 80% irrigation level (i.e. 80% of crop evapotranspiration) is the most advantageous treatment when water is not limited. However, when higher water productivity and the possibility of using the water saved are taken into consideration during severe drought conditions, 60% irrigation level treatment is recommended

Effects of roof insulation on the thermal conditions of a medium scaled tropical enclosed giant freshwater prawn (Macrobrachium rosenbergii) hatchery

This study was conducted to evaluate the effects of roof thermal insulation on the indoor thermal environment of an existing enclosed giant freshwater prawn hatchery in relation to human thermal comfort and the thermal requirement for optimal larval growth. A typical medium scaled enclosed hatchery in Ipoh, Malaysia was chosen for this study. Thermal performances of five thermal insulation materials installed on the roof of the building were studied using Integrated Environmental Solutions (IES) Virtual Environment software. Results showed no significant differences for indoor air temperatures reduction among the insulation materials. However, the installation of roof insulation gave a cooler indoor thermal environment and provided a suitable water temperature/ improved water thermal condition for the prawn larviculture. The study also suggested the aluminium foil was the best insulation for the partially transparent roof of the building