Detecting diagnostic accuracy of two biomarkers through a bivariate log-normal ROC curve

In biomedical research, two or more biomarkers may be available for diagnosis of a particular disease. Selecting one single biomarker which ideally discriminate a diseased group from a healthy group is confront in a diagnostic process. Frequently, most of the people use the accuracy measure, area under the receiver operating characteristic (ROC) curve to choose the best diagnostic marker among the available markers for diagnosis. Some authors have tried to combine the multiple markers by an optimal linear combination to increase the discriminatory power. In this paper, we propose an alternative method that combines two continuous biomarkers by direct bivariate modeling of the ROC curve under log-normality assumption. The proposed method is applied to simulated data set and prostate cancer diagnostic biomarker data set.     

Minimum variance rectangular designs for U-statistics

We consider a certain class of rectangular designs for incomplete U-statistics based on Latin squares and show it to be optimal with respect to the minimal variance criterion. We also show it to be asymptotically efficient when compared with the corresponding complete statistics, as well as uniformly more efficient than the random subset selection. We provide the necessary and sufficient conditions for the existence of our design and give some examples of applications.     

Improved Approximation Algorithms for Maximum Graph Partitioning Problems

We consider the design of approximation algorithms for a number of maximum graph partitioning problems, among others MAX-k-CUT, MAX-k-DENSE-SUBGRAPH, and MAX-k-DIRECTED-UNCUT. We present a new version of the semidefnite relaxation scheme along with a better analysis, extending work of Halperin and Zwick (2002). This leads to an improvement over known approximation factors for such problems. The key to the improvement is the following new technique: It was already observed by Han et al. (2002) that a parameter-driven choice of the random hyperplane can lead to better approximation factors than obtained by Goemans and Williamson (1995). But it remained difficult to find a “good” set of parameters. In this paper, we analyze random hyperplanes depending on several new parameters. We prove that a sub-optimal choice of these parameters can be obtained by the solution of a linear program which leads to the desired improvement of the approximation factors. In this fashion a more systematic analysis of the semidefinite relaxation scheme is obtained.     

Ergonomic intervention in aonla pricking operation during preserve preparation in food processing industries

Aonla is an important Indian fruit crop with great potential for processing into various quality products. Aonla preserve making is an important economic activity in our country. The pricking methods are age old, hence a hand operated aonla pricking machine was introduced in preserve making industries to speed up the pricking task. OWAS and RULA two of the most commonly used ergonomic assessment tools were evaluated for their efficacy in the assessment pricking along with Rating of perceived exertion scale. Analysis of working posture using RULA revealed that the pricking task with existing methods i.e. fork and hand tool requires immediate investigation and changes in working posture while with machine pricking investigations and changes are required soon. The results of OWAS indicated that the posture maintained while pricking with existing methods need to be changed in future planning while with machine was acceptable. The subjective assessment revealed that machine pricking was less exerting activity as compared to the existing methods. The preserve prepared from machine pricked fruit was most acceptable among consumers. Hence, in the form of machine ergonomic intervention was brought about in preservation industries which have proved beneficial for workers in terms of their safety and productivity.     

Ergonomic evaluation of conventional and improved methods of aonla pricking with women workers

Conventional and improved methods of aonla pricking were evaluated ergonomically on an experiment conducted for 20 minute with women workers. The working heart rate, energy expenditure rate, total cardiac cost of work and physiological cost of work with conventional tools varied from 93-102 beats.min-1, 6-7.5 kJ.min-1, 285-470 beats, 14 -23 beats.min-1 while with machine varied from 96-105 beats.min-1, 6.5-8 kJ.min-1 , 336-540 beats, 16-27 beats.min-1 respectively. OWAS score for conventional method was 2 indicating corrective measures in near future while with machine was 1 indicating no corrective measures. Result of Nordic Musculoskeletal Questionnaire revealed that subjects complaint of pain in back, neck, right shoulder and right hand due to unnatural body posture and repetitive movement with hand tool. Moreover pricking was carried out in improper lighting conditions (200-300 lux) resulting into finger injuries from sharp edges of hand tool, whereas with machine no such problems were observed. Output with machine increased thrice than hand pricking in a given time. Machine was found useful in terms of saving time, increased productivity, enhanced safety and comfort as involved improved posture, was easy to handle and operate, thus increasing efficiency of the worker leading to better quality of life.     

Intervention of drudgery reducing technologies in agriculture and impact evaluation

Agriculture is main source of livelihood for majority of the population in India. Agriculture has been established as one of the drudgery prone occupation of unorganized sector due to lack of access to improved agricultural technologies. The present study was planned to assess intervention of drudgery reducing technologies in agriculture and its impact evaluation. The drudgery areas/activities in agriculture were identified. Participatory field level skill training for proper use of the ergonomically improved farm technologies were given to men and women in separate groups. An intervention package consisting of improved sickle, wheel hand hoe, capron, cot bag and protective gloves was introduced in village Shahpur. Data were collected to quantify the impact of intervention on the level of drudgery of worker before and after the technology intervention from sample of 30 respondents (15 male and 15 female) selected randomly from village Shahpur. Gain in knowledge and change in awareness level were calculated after the training.Evaluation of field validation of technology on drudgery of men & women was done after its use in the field conditions. A significant gain in awareness was observed among both men(2.6) & women (3.0) whereas the gain in knowledge was more among men (6.6) than women (4.5). In evaluation of field validation of technology on drudgery it was found that all the five technologies reduced the drudgery of men as well as women. However wheel hand hoe was used successfully by men in comparison to women who preferred to use their conventional technology i.e improved long-handled hoe. Evaluation of validation trials of the technologies reported that improved sickle was used successfully by both men & women farmers. More than half of the men farmers (53.3%) & only 13.3 percent women farmers preferred the wheel hand hoe over the traditional one as they found it four times more efficient in terms of time, energy & money saving. Cot bag was preferred by the entire sample. Capron was preferred by four-fifth of the men farmers (80.0%) whereas women farmers did not prefer it much. Only one third of men (33.3%) & 26.7 percent of women farmers preferred using gloves while harvesting of guar & picking of cotton.     

Occupational health hazards & efficacy of protective masks in threshing operation

The study was conducted on 20 farm workers to identify the occupational health hazards in threshing operation. Four different protective masks were given and tested on various parameters. Respondents reported respiratory health problems which were mainly due to heat and organic dust in the surroundings. All respondents reported irritation in eyes and throat followed by nose (85.0%) and ears (75.0%). Musculo-skeletal problems were reported showing severe to very severe discomfort in lower arms (m.s. = 3.8), upper back (3.6) and upper arms (3.4). Overall discomfort score (ODS) was 7.6 depicting high level of discomfort. Peak expiratory flow rate was reduced by 6.6 % depicting reduced capacity of lungs after day long work in polluted environment. Hood mask was highly acceptable as it showed lowest breathing resistance. Leakage of dust from sides and rate of sweating was medium. Hence, use of hood mask would be helpful to achieve the ergonomics objective of reducing health problems and improving performance.