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Replenishment Policy for Pareto Type Deteriorating Items With Quadratic Demand under Partial Backlogging And Delay in Payments
Get PDFThe present model develops a replenishment policy in which the demand rate is quadratic polynomial-time function. Deterioration rate is a Pareto type function. Shortages are partial backlogging and delay in payments are allowed. Holding cost is a linear function of time. The backlogging rate varies with the waiting duration for the next replenishment. The present paper determines the optimal policy for the individual by minimizing the total cost. The optimization procedure has been explained by a numerical example and a detailed sensitivity analysis of the optimal solution has been carried out to display the effect of various parameters
Analytics of machine replacement decisions: economic life vs real options
No full textPurpose: Despite the existence of multiple asset replacement theories, the economic life replacement method remains a major practical technique for making rational machine replacement decisions. The purpose of this paper is to bridge this method with comprehensive data analytic tools and make it applicable it to modern business reality with abundant data on operating and replacement costs. Design/methodology/approach: This study employs operations research, discrete and continuous optimization, applied mathematical modeling, data analytics, industrial economics and real options theory. Findings: Constructed stochastic algorithms extend the deterministic economic life method and are compared to the contemporary theory of stochastic asset replacement based on real options and dynamic programming. It is proven that both techniques deliver similar results when the cost volatility is small. A major theoretic finding is that the cost uncertainty speeds up the replacement decision. Research limitations/implications: This research suggests that the proposed stochastic algorithms may become an important tool for managerial decisions about replacement of many similar machines with detailed data on operating and replacement costs. Originality/value: Compared to the real options replacement theory, major advantages of the proposed algorithms are that they work equally well for any distribution of age-dependent stochastic operating cost. The algorithms are tested on a real industrial case about replacement of medical imaging devices. Numeric simulation supports obtained analytic outcomes
Non-equal-life asset replacement under evolving technology: A multi-cycle approach
No full textThis paper studies the cost-minimizing serial asset replacement problem under changing operating and replacement costs. Technological improvements affect these costs in different ways, which leads to different duration of sequential replacement cycles of the same asset. Therefore, a firm should optimize a chain of consecutive asset replacements using available information about future costs. We offer a novel multi-cycle algorithm for making such replacement decisions and prove that it converges to the infinite-horizon solution when the number of cycles increases. Important qualitative properties of the obtained optimal non-equal-life replacement strategies are derived, and practical recommendations are discussed
Effect of Feeding a Low Level of Encapsulated Fish Oil to Dairy Goats on Milk Yield, Composition, and Fatty Acid Profile
No full textContradictory results have been found in the response of dairy goats to the supplementation of fish oil in their diet to improve the n-3 polyunsaturated fatty acids (PUFA) in milk. The responses to the inclusion of fish oil in the diet of ruminants either induced milk fat depression, increased milk fat content, and/or negatively impacted milk yield. The objective of this study was to determine whether including a low dose of encapsulated fish oil in the diet of goats can modify yield, milk composition, and the fatty acid (FA) profile of milk. Ten Alpine goats were divided into two homogeneous subgroups and assigned to either the control or experimental diet. The control animals received the basal diet without supplementation of fish oil, whereas the experimental group was given the same basal diet supplemented with encapsulated fish oil (1.14 g /kg of concentrate) for 56 days. Milk samples were analyzed for chemical composition and FA profile. The inclusion of encapsulated fish oil in the goat diet did not affect the yield and composition of goat milk. The effect of diet was not significant on the FA profile of goat milk, except that 20:0 was lower (P \u3c 0.05) in the milk of goats that received fish oil. The low dose of encapsulated fish oil supplement used in this study did not impact (P \u3e 0.05) the PUFA content of goat milk or milk composition and yield; however, the atherogenicity index (AI), which is beneficial to heart health, was lower (P \u3c 0.05) in the milk of goats that received fish oil as a supplement in their diet compared to the control
Effects of atmospheric pressure plasma jet treatment duration to the viability of hela cells and microtissues
No full textNon-thermal atmospheric plasma jet (NTAPPJ) is believed to be effective in treating monolayer cells cultured in-vitro due to the oxidative stresses induced. However, it is controversial whether studying the impact of plasma to cells in monolayer can be representative to a model close to the in-vivo tissues. This study revealed and compared the effects of NTAPPJ treatment directly to both monolayer of HeLa cells and microspheroids in the culture media, at different exposure time from 15 to 60 seconds at a fixed power of 80 W. Optical emission spectroscopy (OES) revealed that the plasma applied to the cells is rich in hydroxyl, nitrogen, oxygen and argon species. The experimental results revealed that the treatment time from 15 seconds onwards was detrimental to the monolayer of cells, but not to the spheroids compared with the negative controls. After long NTAPPJ exposure, the HeLa cells in the spheroids were found viable, regardless of the plasma exposure time applied. The multicellular structure of the spheroids has prevented the penetration of free radicals into the cells encapsulated in the spheroids
Green chemistry-assisted synthesis of CuO nanoparticles: Reaction optimization, DNA cleavage, and DNA binding studies
No full textCopper nanoparticles show considerable antibacterial, anti-fungal and related effects in comparison with bulk CuO and have been explored for their biological applications. In this work green synthesis approach was adopted to synthesize CuONps utilizing Syzygium aromaticum bud extract. CuONps showed a sharp band around 298 nm in UV–Vis spectrum, affirming their formation. The average size of synthesized CuONps was inspected by Debye-Scherrer equation using PXRD spectrum and was found 70 nm. Interaction study of CuONps with Calf-Thymus DNA have been investigated which has given significant results. The CuONps have also shown 20% DNA cleavage activity against E.coli DNA
Sperm miR-15a and miR-29b are associated with bull fertility
No full textMicroRNAs modulate male fertility by regulating gene expression. In this study, dynamics of sperm miR-15a, miR-29b and miR-34a from high fertility (HF) and low fertility (LF) bulls using RT-qPCR were evaluated. Bioinformatic tools were employed to ascertain genes of interest of the sperm miRNAs. The expression levels of p53, BCL2, BAX and DNMT1 in bull spermatozoa were determined by immunoblotting. MicroRNA levels of miR-15a and miR-29 were higher in LF sires when compared with those present in HF bulls. Expression levels of miR-34a did not differ between the two groups. We found an inverse correlation between miR-15a and bull fertility. MiR29-b was also negatively associated with fertility scores. BCL2 and DNMT1 were higher in HF bulls while BAX was higher in the LF group. Our data showed a positive correlation between BCL2 and bull fertility. In addition, DNMT1 was positively associated with bull fertility. Furthermore, levels of BAX were negatively linked with bull fertility scores. Identification of miRNAs found in the spermatozoa of sires with different in vivo fertility helps understand the alterations in the fertilising capacity from cattle and other mammals. These potential biomarkers can be used in reproductive biotechnology as fertility markers to assess semen quality and predict male fertility
Purification and Pyrolysis of Bacterial Cellulose from Kombucha Pellicle
Get PDFKombucha SCOBY pellicle formed as a waste product in the kombucha tea fermentation industry can be used as a potential source for bacterial cellulose. The research compared four simple, scalable purification methods for the purification of this jelly-like cellulosic matrix containing bacteria, yeast cells, proteins, and polyphenols as impurities. The method using two successive 1.0 M NaOH washing at 90°C, followed by the treatment of 1.5 % (w/w) aq. NaOCl for 2h was the most effective method and gave the purified cellulose sample the highest Leucometer whiteness value of 81.4±4.8. The purified cellulose samples were analyzed by FT-IR, TGA, SEM, EDS, and water absorption at room temperature. After purified, the cellulose samples were pyrolyzed, and graphene oxide was directly produced at 600 to 800°C. The pyrolysis samples were analyzed by FT-IR, SEM, RAMAN, and ZETA potential
Viral suppression and factors associated with failure to achieve viral suppression among pregnant women in South Africa
No full textObjective:To describe viral load levels among pregnant women and factors associated with failure to achieve viral suppression (viral load ≤50 copies/ml) during pregnancy.Design:Between 1 October and 15 November 2017, a cross-sectional survey was conducted among 15-49-year-old pregnant women attending antenatal care (ANC) at 1595 nationally representative public facilities.Methods:Blood specimens were taken from each pregnant woman and tested for HIV. Viral load testing was done on all HIV-positive specimens. Demographic and clinical data were extracted from medical records or self-reported. Survey logistic regression examined factors associated with failure to achieve viral suppression.Result:Of 10052 HIV-positive participants with viral load data, 56.2% were virally suppressed. Participants initiating antiretroviral therapy (ART) prior to pregnancy had higher viral suppression (71.0%) by their third trimester compared with participants initiating ART during pregnancy (59.3%). Booking for ANC during the third trimester vs. earlier: [adjusted odds ratio (AOR) 1.8, 95% confidence interval (CI):1.4-2.3], low frequency of ANC visits (AOR for 2 ANC visits vs. ≥4 ANC visits: 2.0, 95% CI:1.7-2.4), delayed initiation of ART (AOR for ART initiated at the second trimester vs. before pregnancy:2.2, 95% CI:1.8-2.7), and younger age (AOR for 15-24 vs. 35-49 years: 1.4, 95% CI:1.2-1.8) were associated with failure to achieve viral suppression during the third trimester.Conclusion:Failure to achieve viral suppression was primarily associated with late ANC booking and late initiation of ART. Efforts to improve early ANC booking and early ART initiation in the general population would help improve viral suppression rates among pregnant women. In addition, the study found, despite initiating ART prior to pregnancy, more than one quarter of participants did not achieve viral suppression in their third trimester. This highlights the need to closely monitor viral load and strengthen counselling and support services for ART adherence
The Impact of Nonlinear Harvesting on a Ratio-dependent Holling-Tanner Predator-prey System and Optimum Harvesting
Get PDFIn this paper, a Holling-Tanner predator-prey model with ratio-dependent functional response and non-linear prey harvesting is analyzed. The mathematical analysis of the model includes existence, uniqueness and boundedness of positive solutions. It also includes the permanence, local stability and bifurcation analysis of the model. The ratio-dependent model always has complex dynamics in the vicinity of the origin; the dynamical behaviors of the system in the vicinity of the origin have been studied by means of blow up transformation. The parametric conditions under which bionomic equilibrium point exist have been derived. Further, an optimal harvesting policy has been discussed by using Pontryagin maximum principle. The numerical simulations have been presented in support of the analytical findings