Validation of Ergonomics Model for Estimating Work Productivity and Quality in Manual Handling Activities

Tujuan penelitian ini adalah melakukan uji validasi model ergonomi tentang waktu pergerakan kerja untuk mengukur produktivitas dan kualitas kerja. Model ini dikembangkan berdasarkan interaksi antara parameter-parameter postur kerja, masa beban dan dimensi tempat kerja. Ekseperimen dilakukan untuk mensimulasikan aktivitas pengangkatan beban dengan melibatkan pekerja yang berusia diantara 21 hingga 25 tahun. Pekerja tersebut diinstruksikan untuk mengangkat tiga masa beban yang berbeda yaitu 2 kilogram, 6 kilogram dan 10 kilogram ke atas meja kerja dengan tinggi masing-masing 55 cm dan 76 cm dengan menggunakan dua postur pengangkatan, postur membungkuk (Stooping) dan postur berjongkok (Squating). Aktivitas pengangkatan ini direkam dengan menggunakan handycam dan kalibrasi dilakukan untuk menentukan skala gambar terhadap benda nyata. Uji statistik t digunakan untuk menguji kesahihan model. Hasil uji ini menunjukkan bahwa tidak ada perbedaan yang siginifikan antara waktu pergerakan nyata dengan waktu pergerakan yang ditentukan dengan model. Dengan demikian model yang dikembangkan adalah valid pada tingkat signifikansi 1%, 5% dan 10% sehingga model dapat diaplikasikan

Effects of timed artificial insemination following estrus synchronization in postpartum beef cattle.

The objectives of this study were to evaluate estrus response and pregnancy rates resulting from timed artificial insemination (AI) following estrus synchronization using CIDR in postpartum beef cattle. A total of 100 cows were randomly divided into three groups. Groups 1, 2 and 3 were artificially inseminated at 48-50 h(n=30), 53-55 h(n=30) and 58-60 h (n=40) after CIDR removal, respectively. Estrussynchronization was carried out using a CIDR containing 1.38 mg progesterone. All cows were given 2 mg estradiol benzoate, intramuscularly on the day of CIDR insertion (D 0). The CIDR was removed after 8 days and 125 μg of prostaglandin F2α(PGF2α) was injected intramuscularly. One day after CIDR removal all cows were given 1 mg of estradiol benzoate intramuscularly (D 9). Cows were observed visually for estrus after removal of CIDR. Between 30 and 32 days after timed AI, pregnancy was determined using transrectal ultrasonography. The first estrus observation which is approximately 32 h after CIDR removal showed no significant difference (P>0.05) among the three groups. The onset response of estrus after 32 h removal of CIDR was less than 10% in all three group s 6.6% (G1), 6.8% (G2) and 7.3% (G3). Furthermore, percentages of estrus response (D 10) following CIDR removal were 76.6%, 75.0% and 77.5%. The difference between on D9 and D10 estrus response were statistically significant (P<0.05). The pregnancy rates were 23.3% (G1), 26.6% (G2) and 37.5% (G3), which were not significant (P>0.05)

A stochastic joint model for longitudinal and survival data with cure patients

Many medical investigations generate both repeatedly-measured (longitudinal) biomarker and survival data. One of complex issues arises when investigating the association between longitudinal and time-to-event data when there are cured patients in the population, which leads to a plateau in the survival function S(t) after sufficient follow-up. Thus, usual Cox proportional hazard model Cox (1972) is not applicable since the proportional hazard assumption is violated. An alternative is to consider survival models incorporating a cure fraction. In this paper we present a new class of joint model for univariate longitudinal and survival data in presence of cure fraction. For the longitudinal model, a stochastic Integrated Ornstein-Uhlenbeck process will be presented. For the survival model a semiparametric survival function will be considered which accommodate both zero and non-zero cure fractions of the dynamic disease progression. Moreover, we consider a Bayesian approach which is motivated by the complexity of the model. Posterior and prior specification needs to accommodate parameter constraints due to the nonnegativity of the survival function. A simulation study is presented to evaluate the performance of this joint model

A Semiparametric Joint Model for Longitudinal and Time-to- Event Univariate Data in Presence of Cure Fraction

Many medical investigations generate both repeatedly-measured (longitudinal)biomarker and survival data. One of complex issue arises when investigating the association between longitudinal and time-to-event data when there are cured patients in the population, which leads to a plateau in the survival function S(t) after sufficient follow-up. Thus, usual Cox proportional hazard model Cox (1972) is not applicable since the proportional hazard assumption is violated. An alternative is to consider survival models incorporating a cure fraction. In this paper we present a new class of joint model for univariate longitudinal and survival data in presence of cure fraction. For the longitudinal model, a stochastic Integrated Ornstein-Uhlenbeck process will present, and for the survival model a semiparametric survival function will be considered which accommodate both zero and non-zero cure fractions of the dynamic disease progression. Moreover, we consider a Bayesian approach which is motivated by the complexity of the model. Posterior and prior specification needs to accommodate parameter constraints due to the nonnegativity of the survival function. A simulation study is presented to evaluate the performance of this joint model

A confirmatory factor analysis in a study of consumer complaint behaviour, satisfaction with complaint handling and relationship quality

A study was conducted to examine the relationships of consumer complaint behaviour, satisfaction with complaint handling and relationship quality in the Malaysian mobile phone services industry. A total of 285 complainers of mobile phone users were selected as the respondents. This paper presents the results of confirmatory factor analysis (CFA), average variance extracted (AVE) and construct reliability (CR) of the study. The CFA measurement model which consist of public complaint soft action (PCSA), public complaint extreme action (PCEA), private complaint soft action (PVSA), private complaint extreme action (PVEA), satisfaction with complaint handling (SATCOM) and relationship quality show excellent goodness-of-fit with χ² = 638.781, df = 291, χ²/df = 2.195, TLI = .926, NFI = .894, CFI=.938, PNFI = .741 and RMSEA = .069 respectively. The model has shown convergent and discriminant validity with AVE and CR fulfilled the requirements. The results indicate that the model can be used for further analysis

Effects of copper overload on hepatic lipid peroxidation and antioxidant defense in rats

The influence of copper (Cu) overload on hepatic lipid peroxidation and antioxidation defense capacity was studied by overloading rats with copper sulphate orally (500 mg Cu/kg bw) 5 d/w for 8 w. Malondialdehyde (MDA), Cu-Zn superoxide dismutase (SOD), and Se-glutathione peroxidase (GSH-Px) were measured in serum and liver homogenate at 2, 4 and 8 w of dosing. Liver Cu concentration and alanine aminotransferase (ALT) activity were also determined. As Cu loading progressed, there were multiparameter changes with significant ALT elevation, increased MDA concentrations in serum and liver homogenate, and dramatic declines of SOD and GSH-Px activities in erythrocytes and whole blood respectively, along with marked elevation of hepatic Cu in the Cu-dosed group. Excessive Cu accumulation in the liver depressed SOD and GSH-Px activities and resulted in high MDA in serum and liver homogenate due to the lipid peroxidation induced by the Cu overload

Effect of Rake Angle on Stress, Strain and Temperature on the Edge of Carbide Cutting Tool in Orthogonal Cutting Using FEM Simulation

Demand for higher productivity and good quality for machining parts has encourage many researchers to study the effects of machining parameters using FEM simulation using either two or three dimensions version. These are due to advantages such as software package and computational times are required. Experimental work is very costly, time consuming and labor intensive. The present work aims to simulate a three-dimensional orthogonal cutting operations using FEM software (deform-3D) to study the effects of rake angle on the cutting force, effective stress, strain and temperature on the edge of carbide cutting tool. There were seven runs of simulations. All simulations were performed for various rake angles of -15 deg, -10 deg, -5 deg, 0 deg, +5 deg, +10 deg, and +15 deg. The cutting speed, feed rate and depth of cut (DOC) were kept constant at 100 m/min, 0.35 mm/rev and 0.3 mm respectively. The work piece used was ductile cast iron FCD500 grade and the cutting tool was DNMA432 series (tungsten, uncoated carbide tool, SCEA = 0; and radius angle 55 deg). The analysis of results show that, the increase in the rake angle from negative to positive angle, causing the decrease in cutting force, effective stress and total Von Misses strain. The minimum of the cutting force, effective stress and total Von Misses strain were obtained at rake angle of +15 deg. Increasing the rake caused higher temperature generated on the edge of carbide cutting tool and resulted in bigger contact area between the clearance face and the workpiece, consequently caused more friction and wear. The biggest deformation was occurred in the primary deformation zone, followed by the secondary deformation zone. The highest stress was also occurred in the primary deformation zone. But the highest temperature on the chip usually occurs in secondary deformation zone, especially in the sliding region, because the heat that was generated in the sticking region increased as the workpiece was adhered by the tool and later it was sheared in high frictional force

Effects of resynchronization with progesterone and prostaglandin F2• on estrus response and pregnancy rate in beef cattle

This experiment was designed to compare the estrus response and pregnancy rate of cows first synchronized using CIDR with cows that were resynchronized after failing to display estrus. Estrus response and pregnancy rate were also compared between cows resynchronized with either CIDR or prostaglandin F2• (PGF2•). Initially, 140 Brangus cows were synchronized with CIDR. About 30 days after Artificial Insemination (AI), cows were checked for pregnancy using ultrasound and those that remain open were divided into two groups and resynchronized with either CIDR or two injections of PGF2• at 11 days interval. All cows were observed visually for estrus response for a period of 2 h at 12 h interval, starting immediately after CIDR removal or after the second injection of PGF2•. Cows were in estrus when they mounted if at least 3 times during the period of observation. Following removal of CIDR and second injection of PGF2•, cows were inseminated 60 and 70 h later, respectively. There were no significant differences (p>0.05) in estrus response and pregnancy rate between cows initial synchronization and resynchronization with CIDR protocol. Although, statistically not significant there was relatively higher percentage of estrus response (81.6 vs. 70%) and pregnancy rate (30.6 vs. 28.0%) in cows resynchronized with CIDR than cows resynchronized with PGF2•