We examine a single machine scheduling problem with step-improving jobs in which job processing times decrease step-wisely over time according to their starting times. The objective is to minimize total completion time which is defined as the sum of completion times of jobs. The total completion time is frequently considered as an objective because it is highly related to the total time spent by jobs in the system as well as work-in-progress. Many applications of this problem can be observed in the real world such as data gathering networks, system upgrades or technological shock, and production lines operated with part-time workers in each shift. Our goal is to develop a scheduling algorithm that can provide an optimal solution. For this, we present an efficient branch and bound algorithm with an assignment-based node design and tight lower bounds that can prune branch and bound nodes at early stages and accordingly reduce the computation time. In numerical experiments well designed to consider various scenarios, it is shown that the proposed algorithm outperforms the existing method and can solve practical problems within reasonable computation time.
This study aimed to reconfirm the sex change scale and pattern of Tegillarca granosa. Although the sex ratio (female : male, female proportion) of T. granosa was 1:2.32 (30.2%) at the initial stage (2011) of the study, it was 1:0.94 (51.5%) after one year (2012) in the same population. The increase of the female proportion was greater in the 2+ year class (23.0%) when compared to the 1+ year class (19.2%). Overall, sex change ratio of 37.6% was observed in this population of T. granosa. The sex change ratio of the 2+ year class (39.3%) was higher than that of the 1+ year class (35.3%). And sex change ratio in the males (42.2%) was higher than that in the females (26.9%). The female proportion was the opposite of the result from 2006~2007, and one of the causes was presumed to be the difference in cumulative water temperature during the gonadal inactive stage (winter).
Fluorescent bacteria were isolated from sporocarps that browned into various mushrooms during survey at places of the production in Korea. We examined the pathogenicity, biodiversity, and genetic characteristics of the 19 strains identified as Pseudomonas tolaasii by sequence analysis of 16S rRNA and White Line Assay. The results emphasize the importance of rpoB gene system, fatty acid profiles, specific and sensitive PCR assays, and lipopeptide detection for the identification of P. tolaasii. As a result of these various analyses, 17 strains (CHM03~CHM19) were identified as P. tolaasii. The phylogenetic analysis based on the 16S rRNA gene showed that all strains were clustered closest to P. tolaasii lineage, two strains (CHM01, CHM02) were not identified as P. tolaasii and have completely different genetic characteristics as a result of fatty acids profile, specific and sensitive PCR, lipopetide detection, rpoB sequence and REP-PCR analysis. Pathogenicity tests showed 17 strains produce severe brown discolouration symptoms to button mushrooms and watersoaking of sporophore tissue within three days after inoculation. But two strains did not produce discolouration symptoms. Therefore, these two strains will be further investigated for correct species identification by different biological and molecular characteristics.
In the field of mental health care, long-term healing programs have gained widespread recognition for their effectiveness in promoting well-being. However, the efficacy of shorter-term interventions, such as 1-night 2-day programs, remains relatively understudied. The primary objective of this initiative is twofold: firstly, to enhance the overall well-being and resilience of participants, and secondly, to investigate the program's potential to ameliorate specific mental health indicators. These indicators include physical stress levels, autonomic nervous system health, brain activity, brain stress, and concentration. A 1-night 2-day mental health healing program was implemented for 560 civil servants from Jeollanam-do (mean age 47.87 yrs). The focus was on measuring changes through baseline assessments before participation and post-program assessments upon completion. Measurements included physical stress index, autonomic nervous system health, brain activity level, brain stress, and brain concentration. There was a significant decrease in physical stress, as well as a significant decrease in autonomic nervous system health (p<0.05). Although there was no significant difference in brain activity level, there was a tendency for brain activity level to stabilize in the high-frequency range. Additionally, a significant decrease in stress levels and an improvement in concentration were observed. Incorporating 1-night 2-day relaxation programs into our daily lives offers a holistic approach to caring for both our physical and mental health, providing essential moments of rejuvenation and self-care that contribute to overall well-being and fulfillment.
Fashion stress is a pertinent aspect of modern consumer culture that has been underexplored in academic research. This study developed a conceptual framework of fashion stress and a multidimensional scale to measure consumers’ fashion stress. The qualitative study included literature reviews on consumption stress, shopping stress, and consumer behavior, as well as focus group interviews to gain insight into various dimensions of fashion stress. NVivo 12.0 was used to analyze the qualitative data and identify core categories following the grounded theory methodology. The quantitative study involved a preliminary and a primary surveys to verify the validity and reliability of the fashion stress scale. A total of 220 questionnaires were used for data analysis. The results show that fashion stress consists of eight factors: care, shopping, fit, brand, financial, closet, style, and disposal. Choice difficulty plays a significant role in all factors of fashion stress. Moreover, shopping stress had a negative impact on impulse buying, while other factors such as fit, brand, closet, and disposal stress had a positive impact on impulse buying. Thus, fashion stress is a potential antecedent of impulsive consumer behavior. The results also confirm the validity and reliability of the scale. The fashion stress scale developed in this study offers researchers a valuable tool for assessing and understanding consumer experiences.