Showing papers by "De La Salle University published in 1999"

Overcoming Obstacles to Understanding and Solving Word Problems in Mathematics

Abstract: The trouble students have with solving word problems often comes from the difficulty in understanding the problem structure embedded in the problem text. This research was conducted to study the interactive effects of learner and instructional variables on understanding and solving word problems among Filipino‐English bilingual grade school students in the Philippines. The results showed better understanding and solution performance (1) when problems were written in the students’ first language, (2) when the problems were re‐worded to state more explicitly the relationship among the known and unknown quantities, (3) for students in higher levels of schooling and (4) for students with higher levels of academic achievement. The effects of re‐wording were mediated by the effects of the language; and the effects of language also varied between the highand low‐achievement students. In most cases where the students’ performance improved, the improvement seems to be due to better comprehension of the te...

Development of a Low Capital Investment Reactor System: Application for Plant Cell Suspension Culture

Abstract: Growth of plant cell cultures is demonstrated in an uncontrolled, simple, and inexpensive plastic-lined vessel. Sustained specific growth rates of 0.22 day -1 for Hyoscyamus muticus cell suspension cultures are achieved in a low-cost gas-sparged bioreactor configuration (6.5 L working volume, wv) which is comparable to an optimized 5 L wv mechanically agitated fermentor. In an effort to reduce bioreactor costs, the need for an autoclavable vessel was eliminated. Sterilization is achieved by separate autoclaving of the plastic liner and by gas-phase sterilization using ethylene oxide. The initial run sterilized with ethylene oxide displayed a long lag, apparently due to residual sterilant gas. Because ethylene oxide could eliminate costs associated with autoclave rated vessels, a quantitative basis for aeration time was developed by experimental measurements and modeling of diffusion in the polymer liner. Operational techniques to eliminate toxicity are implemented to grow 0.2 kg dry weight of plant cells in 13 days in a 40 L (28.5 L wv) air-lift bioreactor without autoclave sterilization. The biomass yields for all reactors were statistically indistinguishable from shake flask culture.

Microflora of banh men, a fermentation starter from Vietnam

Abstract: In this study Banh mensamples obtained from Vietnam were analysed in terms of pH, moisture content and fungal composition. The banh men pH proved to be acidic with a mean pH of 5.76. Moisture content was 13.6%. Total mould and yeast counts yielded 1.3 × 106 and 4.3 × 106 c.f.u./g-fresh sample, respectively. A total of 53 fungal isolates were obtained from 20 moulds and 33 yeasts. The mould isolates were identified as Rhizopus oryzae, Mucor indicus, Mucor circinilloides, and Amylomyces rouxii. The yeast isolates were identified as Saccharomyces cerevisiae, Hyphopichia burtonii, Saccharomycopsis fibuligera, Pichia anomala, and Candida sp. Based on the parameters used in this study, it can be deduced that banh men is similar to ragi and other Asian fermentation starters.

Butyltins, Organochlorines and Metal Levels in Green Mussel, Perna viridis L. from the Coastal Waters of the Philippines.

Abstract: Contamination by butyltins (BTs), organochlorine compounds (OCs) and heavy metals was exam ined in green mussels collected along the coastal areas of the Philippines in 1994 and 1997. Significant BTs concentrations revealed widespread contamination along nearshore marine waters. Relatively high BTs concentrations were observed in samples collected from areas with high boating activities, sugges tive that the source of TBT (tributyltin) is coming from antifouling paints. While TBT levels were found to be low in green mussels collected from aquaculture areas, implying minimal usage of BTs for aquaculture activities. The composition of BT derivatives in mussel was in the order of TBT>DBT>MBT, reflective of continuous input of TBT in the coastal waters. Considering the un regulated use of organotins in the country, BTs contamination in the aquatic environment of the Philip pines may increase in the future. Concentrations of OCs in green mussels were less than BTs. Among OCs, PCBs concentrations were found to be relatively high particularly in mussels from Manila Bay. Moreover, metal concentrations found suggest that the anthropogenic loading of Hg, Pb and Cd to the coasts is relatively low, suggestive that the green mussels from these coastal waters are not adversely affected by these metal toxicants and pose no risk for human health. To our knowledge, this is the first comprehensive report on the concentrations of butyltins, organochlorine compounds and heavy metals in soft tissues of green mussels in the Philippines.

Tight Graphs and Their Primitive Idempotents

Abstract: In this paper, we prove the following two theorems. Theorem 1 Let Γ denote a distance-regular graph with diameter d ≥ 3. Suppose E and F are primitive idempotents of Γ, with cosine sequences σ_0, σ_1, …, σ_d and ρ_0, ρ_1, …, ρ_d, respectively. Then the following are equivalent. (i) The entry-wise product E F is a scalar multiple of a primitive idempotent of Γ. (ii) There exists a real number e such that Let Γ denote a distance-regular graph with diameter d ≥ 3 and eigenvalues t_0 > t_1 > … > t_d. Then Jurisic, Koolen and Terwilliger proved that the valency k and the intersection numbers a_1, b_1 satisfy They defined Γ to be tight whenever Γ is not bipartite, and equality holds above. Theorem 2 Let Γ denote a distance-regular graph with diameter d ≥ 3 and eigenvalues t_0 > thetas;_1 > … > t_d. Let E and F denote nontrivial primitive idempotents of Γ. (i) Suppose Γ is tight. Then E, F satisfy (i), (ii) in Theorem 1 if and only if E, F are a permutation of E_1, E_d. (ii) Suppose Γ is bipartite. Then E, F satisfy (i), (ii) in Theorem 1 if and only if at least one of E, F is equal to E_d. (iii) Suppose Γ is neither bipartite nor tight. Then E, F never satisfy (i), (ii) in Theorem 1.

Developing a Web‐based learning module in a basic civil engineering course

Abstract: Many universities worldwide have their own home pages on the World Wide Web accessible to both faculty and students via user‐friendly Web browsers. Thus, education and learning resources must be developed and published on the Web to maximize the usefulness of this new technology in higher education. In line with this thrust, a Web‐based learning module in a basic civil engineering course in structural analysis was developed. This article describes the process, principles, and tools used in developing this learning module. © 2000 John Wiley & Sons, Inc. Comput Appl Eng Educ 7: 235–243, 1999

The Underpricing of Initial Public Offerings in the Philippines from 1987 to 1997

Abstract: In this paper we report returns for initial public offerings (IPOs) in the Philippines and investigate some characteristics found in other countries to affect returns, specifically offer size, firm age, and industry grouping. For a sample of 104 IPOs during the 11-year period 1987 through 1997, we find average initial returns of 22.69 percent. We do not find that offer size, firm age, or industry groupings affect IPO underpricing and conclude from our findings that underwriters who price Philippine IPOs face different regulatory policies, contractual mechanisms, market conditions than those present in other markets.

Dehydration of tert-Butyl Alcohol in Reactive Distillation

Abstract: A system of tert-butyl alcohol can be effectively provided for a chemical heat pump cycle to upgrade low-temperature waste heat energy. This study focuses on an important part of the cycle, an endothermic reaction, specifically the liquid-phase dehydration of tert-butyl alcohol to produce isobutene and water below 373 K.Dehydration is carried out in a reactive distillation column with a catalyst-bed filled with Amberlyst 15 for various reduced pressures and feed flowrates. The use of reactive distillation facilitates complete conversion of the dehydration of tert-butyl alcohol by avoiding strong inhibition of water in this reaction.Experimental results are compared with the results simulated by using an ASPEN PLUS Process Simulator.

Kinetic study on the dehydration of tert-butyl alcohol catalyzed by ion exchange resins

Abstract: The dehydration of tert-butyl alcohol (TBA) in the liquid phase was studied by using an ion exchange resin, Amberlyst 15 (A15) in the H+ form. Experiments were carried out both in a semi-batch reactor and in a continuous stirred tank reactor (CSTR) with wet or dry resins. The results with the dry resin in the semi-batch reactor were different from those with the wet resin due to the swelling of resin in the presence of water. However, the results in CSTR agreed well with those in the semi-batch reactor using the wet resin. A rate equation that considered the inhibition of water was formulated. The experimental results agreed well with the calculated ones. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 854–859, 1999

Pharmacokinetics of bambuterol during oral administration to asthmatic children

Abstract: Regularity is a key element of maintenance drug treatment; compliance is crucial for treatment success Once- or twice-daily intake of a drug is always easier to comply with than regimens requiring more frequent dosing Bronchodilating treatment was used as an example to illustrate how sustained duration of effect can be achieved by two different approaches: oral administration of the terbutaline prodrug bambuterol and inhalation of formoterol Bioanalytical methods were employed to monitor the kinetic fate of bambuterol and formoterol in plasma, urine, or faeces Generated terbutaline in plasma was used as a marker of effect for bambuterol Established clinical laboratory tests were used to assess local and systemic effects of inhaled formoterol compared with salbutamol Recommended doses of bambuterol, 10-20 mg once daily in adults, normally produced plasma concentrations of the active moiety terbutaline within therapeutically relevant limits Dose proportionality for terbutaline makes dosing with bambuterol predictable Compared with adults, children should be given higher doses than indicated by their lower body weight Pharmacokinetic analysis indicated that absorption of bambuterol was slow and multi-phasic and that slow biotransformation to terbutaline occurred both presystemically and systemically Systemically circulating formoterol was rapidly eliminated, the inactive (S;S)-formoterol more rapidly than the active (R;R)-formoterol An inactive phenol glucuronide was the main metabolite, and a previously unknown sulphate metabolite was discovered Duration of systemically mediated cardiovascular or metabolic side-effects of inhaled formoterol seemed not to differ from those of an inhaled systemically equieffective dose of salbutamol There was a trend suggesting that the magnitude of systemic side-effects may be less pronounced after inhalation of formoterol compared with a locally equieffective dose of inhaled salbutamol Both approaches to sustaining stimulation of β2-adrenoceptors have their pros and cons Bambuterol can be dosed orally once daily, but full effect is reached slowly The effect of formoterol is reached within a few minutes, but administration must occur via the lungs, often twice daily Both treatments, however, give 24-h symptom relief during regular treatment

Simulation of Multistage Electrodialysis

Abstract: A simulation for multistage electrodialysis for separation of metal ions is developed. The experimental results for the separation of potassium and sodium ions by a 4-stage electrodialyzer are compared, and can be satisfactorily reproduced by the present simulation method. It is observed that the separation factor increases largely with increasing stage number and flow rate of reflux. The increase in the stage number is effective to achieve a large separation factor and a large recovery fraction of potassium.

Predictors of Life Satisfaction among Filipino Managerial and Professional Women

Abstract: This study examined predictors of life satisfaction reported by 200 Filipino managerial and professional women. Two types of correlates were considered, personal and work-situation characteristics and work experiences and work outcomes. Data were collected using anonymous questionnaires from women working in fashion or cosmetics and banking or financial services. Personal and situational characteristics were generally unrelated to self-reported life satisfaction; however, work experiences and work outcomes were consistently and strongly related to self-reported life satisfaction. Filipino managerial and professional women reporting more positive work experiences and more favorable work outcomes also reported greater life satisfaction.

2D order of self-organizing Kristal maps

Abstract: This paper presents two metrics that measure the disorder of 2D self-organizing maps. These are the average direct neighbor distance and the average unit disorder. This theoretical work on the order of 2D self-organizing maps is done on Kristal maps, a variant of the original Kohonen model. It is shown that Kristal maps, when adequately trained, produce orderings that are superior to any of the known 2D orderings, such as the Canter-diagonal, Morton, Peano-Hilbert, raster-scan, row-prime, spiral, and random orderings.

Analysis of the multiple scattering effects on clouds using Monte Carlo and depolarization lidar method

Abstract: The paper discusses the importance of considering the effect of multiple scattering on lidar data. It is shown that a strong correlation exists between the Monte Carlo and depolarization lidar techniques. Both techniques also point out that the mean correction factor F~ depends on the penetration depth and that F~ approaches a limiting value as the penetration depth increases. The dependence of F~ with penetration depth must be considered in the lidar inversion process. Further studies are being performed to investigate the dependence of the correction factor on the wavelength of the incident radiation and on the size and composition of the particles.

Angstrom coefficient of tropospheric cloud and aerosol derived from a three-wavelength Mie lidar system

Abstract: Clouds and aerosols play an important role on the Earth's radiation budget. One of the optical properties of clouds and aerosols that are needed for radiative transfer calculations is the volume extinction coefficient. This can be retrieved from the LIDAR return signal through an inversion method. The Angstrom coefficient,/spl delta/, which expresses the wavelength dependence of the extinction coefficient is then derived on the assumption of the Angstrom relation. The obtained values /spl delta/ can be used in principle to discriminate between different aerosol types, evaluate the particle size, and determine the size distribution of the particle. In this paper, the data obtained from the three-wavelength LIDAR system and initial results of the extinction coefficients of clouds and aerosols, and its wavelength dependence will be presented. In the manner similar to Grant el al, the difference in the values of the Angstrom coefficient between low-lying aerosols and low-altitude clouds provide a way of discriminating between clouds and aerosol particles.

A comparative analysis of the topological structures of different LPC feature-based speech models

Abstract: Describes initial experimentations done on three LPC (linear predictive coding) derived feature-based speech models: the LPC-cepstrum, the LSP (line spectral pair) and the postfilter-cepstrum (PFL). A comparative analysis of the topological structures of these models is also given. The structures are basically self-organizing feature maps which accept these models as inputs and after training, used to distinguish between isolated word utterances and speakers. A small database of 5 utterances and 4 speakers is initially used. The performance index of isolated word recognition and speaker identification for all models are calculated based on a hit-and-miss ratio and are also discussed. Experimental results reveal that the three parameters are comparable in performance. The LSP has a slight edge over the other two feature vectors in distinguishing isolated words.

Random contact strategy using the Kalman filter to solve the robotic contact uncertainty problem

Abstract: This paper addresses the problem of finding the uncertainties present in a robotic contact. There are two kinds of uncertainties: grasping uncertainties and contact uncertainties. The grasping uncertainty vector contains errors (angles and displacements) associated with improper grasping. The contact uncertainty vector contains errors in angles and positions of nominal contact. A force sensor is used together with Kalman filters to solve the uncertainties. The straightforward use of Kalman filters is found to be effective in finding only some of the uncertainties. The quantities that form dependencies cannot be estimated in this manner. This dependency brings about the problem of observability. The unobservable quantities can be determined using a sequence of contacts. The error covariance matrix of the Kalman filter can indicate the directions of dependency and accuracy of the values estimated. A new contact in any of the dependent directions can be randomly chosen as the next contact to try. The relational transformations between contacts are used to eventually obtain the complete solution. A two dimensional contact situation will be used to demonstrate the effectiveness of the method. Experimental data are also presented to prove the validity of the procedure. Due to the non-linear relationship between the uncertainties and the forces, an extended Kalman filter (EKF) has been used.

The Relation between Gas in Coal Seams and Artificial Coalification Gas Under Hydrothermal Pressure Systems

Abstract: Extensive studies have been carried out on the genetic chemical reaction of coals by many famous researchers Some of the previous studies are as follows: H Potonei[1] initiated the study of coalification F Fischer, et al[2] supported the origin of lignin theory F Bergins[3], Erasmus[4] and R V Wheeler, et al[5] supported the cellulose theory Tropsch[6], Berl and Schmit[7], Horn and Sustsmann[8] and Fuch and Horn[9] developed the systematic investigation on artificial coalification Berl and Schmidt[10] experiments on coalification were checked and confirmed by Schuhmacher and Van Krevelen[11] Two researches on this topic were studied in our country W Funasaka and C Yokokawa[12] discussed the relationship between the genetic origin of coal and its chemical properties at atmospheric conditions by artificial coalification experiments T Yamazaki and R Abe[13] reported the experimental results of the gas evolutions from raw coal during the artificial coalification process following the procedure presented by C Yakakawa