Quantifying signals with power-law correlations: A comparative study of detrended fluctuation analysis and detrended moving average techniques

Detrended fluctuation analysis (DFA) and detrended moving average (DMA) are two scaling analysis methods designed to quantify correlations in noisy non-stationary signals. We systematically study the performance of different variants of the DMA method when applied to artificially generated long-range power-law correlated signals with an {\it a-priori} known scaling exponent $\alpha_{0}$ and compare them with the DFA method. We find that the scaling results obtained from different variants of the DMA method strongly depend on the type of the moving average filter. Further, we investigate the optimal scaling regime where the DFA and DMA methods accurately quantify the scaling exponent $\alpha_{0}$, and how this regime depends on the correlations in the signal. Finally, we develop a three-dimensional representation to determine how the stability of the scaling curves obtained from the DFA and DMA methods depends on the scale of analysis, the order of detrending, and the order of the moving average we use, as well as on the type of correlations in the signal.Comment: 15 pages, 16 figure

OPTIMIZATION OF CULTURE CONDITIONS OF STREPTOMYCES CARPATICUS (MTCC-11062) FOR THE PRODUCTION OF ANTIMICROBIAL COMPOUND

Objective: To improve the antimicrobial compound productivity of Streptomyces carpaticus (MTCC-11062) by optimizing its physical and chemical parameters Methods: Streptomyces carpaticus (MTCC-11062) was isolated from Visakhapatnam sea coast of Bay of Bengal and was screened for its antimicrobial activity by using agar well diffusion method. To improve the production of antimicrobial compound the medium composition and physical parameters were optimized and its productivity was studied against Bacillus cereus (MTCC 430) Escherichia coli (MTCC 443), Candida albicans (MTCC 227) obtained from MTCC, Chandigarh, India. Results: Optimum growth of mycelium and antimicrobial compound production occurred at pH 7.2, agitation 180 rpm and temperature 300C with glucose 10g/L, soyabean meal 2.5g/L, K2HPO4 2g/L, MgSO4 1g/L, NaCl 7.5g/L and trace salts. Conclusion: The optimization of cultural conditions proposed in this paper has effetely improved the antimicrobial compound productivity of Streptomyces carpaticus (MTCC-11062)

Dynamic Pricing with a Prior on Market Response

We study a problem of dynamic pricing faced by a vendor with limited inventory, uncertain about demand, aiming to maximize expected discounted revenue over an infinite time horizon. The vendor learns from purchase data, so his strategy must take into account the impact of price on both revenue and future observations. We focus on a model in which customers arrive according to a Poisson process of uncertain rate, each with an independent, identically distributed reservation price. Upon arrival, a customer purchases a unit of inventory if and only if his reservation price equals or exceeds the vendor’s prevailing price.Institute for Operations Research and the Management Sciences (MSOM society)National Science Foundation (U.S.) (grant IIS- 0428868

Deployment of Supply Chain Security Practices: Antecedents and Consequences

Despite the importance of supply chain security (SCS), there is significant variance regarding the level of deployment of SCS practices across firms and little is known about the efficacy of these practices. This study examines the role of external (coercive pressure) and internal (top management involvement) factors that potentially explain SCS practice deployment and its effect on SCS performance. It also examines the moderating role of organizational culture. In essence, this inquiry examines the role of external and internal forces in a context where organizational action is perhaps effectively mobilized only when both external and internal pressures are salient. Using data from 166 U.S. manufacturing firms, we found that the effects of coercive forces on SCS practice deployment are transmitted via top management involvement. In addition, the effect of top management involvement on SCS practice deployment is more salient for firms with high security‐oriented organizational culture, although a diminishing return was detected. SCS practice deployment was found to be strongly related to SCS performance. We discuss the theoretical contributions and managerial implications based on our findings

Assortment optimisation under a general discrete choice model: A tight analysis of revenue-ordered assortments

The assortment problem in revenue management is the problem of deciding which subset of products to offer to consumers in order to maximise revenue. A simple and natural strategy is to select the best assortment out of all those that are constructed by fixing a threshold revenue $\pi$ and then choosing all products with revenue at least $\pi$. This is known as the revenue-ordered assortments strategy. In this paper we study the approximation guarantees provided by revenue-ordered assortments when customers are rational in the following sense: the probability of selecting a specific product from the set being offered cannot increase if the set is enlarged. This rationality assumption, known as regularity, is satisfied by almost all discrete choice models considered in the revenue management and choice theory literature, and in particular by random utility models. The bounds we obtain are tight and improve on recent results in that direction, such as for the Mixed Multinomial Logit model by Rusmevichientong et al. (2014). An appealing feature of our analysis is its simplicity, as it relies only on the regularity condition. We also draw a connection between assortment optimisation and two pricing problems called unit demand envy-free pricing and Stackelberg minimum spanning tree: These problems can be restated as assortment problems under discrete choice models satisfying the regularity condition, and moreover revenue-ordered assortments correspond then to the well-studied uniform pricing heuristic. When specialised to that setting, the general bounds we establish for revenue-ordered assortments match and unify the best known results on uniform pricing.Comment: Minor changes following referees' comment

Occurrence of testicular microlithiasis in androgen insensitive hypogonadal mice

<b>Background</b>: Testicular microliths are calcifications found within the seminiferous tubules. In humans, testicular microlithiasis (TM) has an unknown etiology but may be significantly associated with testicular germ cell tumors. Factors inducing microlith development may also, therefore, act as susceptibility factors for malignant testicular conditions. Studies to identify the mechanisms of microlith development have been hampered by the lack of suitable animal models for TM.<BR/> <b>Methods</b>: This was an observational study of the testicular phenotype of different mouse models. The mouse models were: cryptorchid mice, mice lacking androgen receptors (ARs) on the Sertoli cells (SCARKO), mice with a ubiquitous loss of androgen ARs (ARKO), hypogonadal (hpg) mice which lack circulating gonadotrophins, and hpg mice crossed with SCARKO (hpg.SCARKO) and ARKO (hpg.ARKO) mice.<BR/> <b>Results</b>: Microscopic TM was seen in 94% of hpg.ARKO mice (n=16) and the mean number of microliths per testis was 81 +/- 54. Occasional small microliths were seen in 36% (n=11) of hpg testes (mean 2 +/- 0.5 per testis) and 30% (n=10) of hpg.SCARKO testes (mean 8 +/- 6 per testis). No microliths were seen in cryptorchid, ARKO or SCARKO mice. There was no significant effect of FSH or androgen on TM in hpg.ARKO mice.<BR/> <b>Conclusions</b>: We have identified a mouse model of TM and show that lack of endocrine stimulation is a cause of TM. Importantly, this model will provide a means with which to identify the mechanisms of TM development and the underlying changes in protein and gene expression

Protein disulfide-isomerase interacts with a substrate protein at all stages along its folding pathway

In contrast to molecular chaperones that couple protein folding to ATP hydrolysis, protein disulfide-isomerase (PDI) catalyzes protein folding coupled to formation of disulfide bonds (oxidative folding). However, we do not know how PDI distinguishes folded, partly-folded and unfolded protein substrates. As a model intermediate in an oxidative folding pathway, we prepared a two-disulfide mutant of basic pancreatic trypsin inhibitor (BPTI) and showed by NMR that it is partly-folded and highly dynamic. NMR studies show that it binds to PDI at the same site that binds peptide ligands, with rapid binding and dissociation kinetics; surface plasmon resonance shows its interaction with PDI has a Kd of ca. 10−5 M. For comparison, we characterized the interactions of PDI with native BPTI and fully-unfolded BPTI. Interestingly, PDI does bind native BPTI, but binding is quantitatively weaker than with partly-folded and unfolded BPTI. Hence PDI recognizes and binds substrates via permanently or transiently unfolded regions. This is the first study of PDI's interaction with a partly-folded protein, and the first to analyze this folding catalyst's changing interactions with substrates along an oxidative folding pathway. We have identified key features that make PDI an effective catalyst of oxidative protein folding – differential affinity, rapid ligand exchange and conformational flexibility

Some reproductive parameters of Zanskari mares reared in an organized farm under tropical climate

The present study was undertaken to record the data on duration of estrus, estrus cycle length, size of the follicle at ovulation, period of gestation and estrus after foaling (foal heat) in respect of Zanskari mares for 4 consecutive breeding seasons (2010–2014). The mares were closely monitored with transrectal ultrasonography for their follicle size variation and to determine size of the follicle at ovulation. The mares were inseminated with frozen thawed semen from Zanskari stallions. This is the first time ever that Zanskari stallion semen was cryopreserved successfully and viable foals were produced by using frozen semen via artificial insemination. The reproductive parameters of the mares of Zanskari breed in India are poorly investigated and thus no reports are available on reproductive characteristics of Zanskari breed till today in the literature. Our results can be useful as a ready reference for some of the reproductive characteristics and traits of Zanskari breed as well as indigenous horses reared under tropical region. The reproductive parameters analysed in the present study are fitting within the characteristics of the other Indian horse breeds reared under this region and the differences may be caused by breed effect and other environmental factors

A branch and efficiency algorithm for the optimal design of supply chain networks

Supply chain operations directly affect service levels. Decision on amendment of facilities is generally decided based on overall cost, leaving out the efficiency of each unit. Decomposing the supply chain superstructure, efficiency analysis of the facilities (warehouses or distribution centers) that serve customers can be easily implemented. With the proposed algorithm, the selection of a facility is based on service level maximization and not just cost minimization as this analysis filters all the feasible solutions utilizing Data Envelopment Analysis (DEA) technique. Through multiple iterations, solutions are filtered via DEA and only the efficient ones are selected leading to cost minimization. In this work, the problem of optimal supply chain networks design is addressed based on a DEA based algorithm. A Branch and Efficiency (B&E) algorithm is deployed for the solution of this problem. Based on this DEA approach, each solution (potentially installed warehouse, plant etc) is treated as a Decision Making Unit, thus is characterized by inputs and outputs. The algorithm through additional constraints named “efficiency cuts”, selects only efficient solutions providing better objective function values. The applicability of the proposed algorithm is demonstrated through illustrative examples