Regular Chain Research Articles

Reducing inventories while improving delivery performance

Industrial coatings are often customer-specific products, which have to be adjusted to the specific application conditions of each application plant. To meet their high specifications, typically more than 15 different raw materials are needed, and the best-fitting supplier is selected. Short lead times and relatively high transport costs require decentralised production. Minimising inventories is therefore difficult. Industry benchmarks show that mid-sized coatings companies typically have a higher ratio of inventories to sales than large companies. Internal benchmarking can reveal optimisation potential if similar-sized and positioned plants are compared on their days of inventory (DOI) as an average of the individual months. By setting DOI targets and introducing regular supply chain telephone conferences with all sites, improvements can be achieved quite easily on excessive inventories. Highlighting the percentage of expired or aged stocks within the total inventory will identify further reduction potential. Here it is important to look at gross values as financially, these expired and aged materials are often already written off. Raw material consignment stocks can be increased in cooperation with procurement while consignment stocks at customers need to be addressed together with sales. Taking these individual measures together, it is possible for even a mid-sized company to achieve a comparable performance to a large company. It is usually assumed that high inventory levels are necessary to achieve a good delivery performance. This is not necessarily true, as the better planning necessary to reduce inventories in a controlled way will also benefit demand planning. Besides, less cluttered warehouses will shorten the time for picking raw materials and increase compliance with first-in, first-out principles. This paper will give an example of how inventories were reduced in Beckers while at the same time lead times were improved. It will be demonstrated that the conventional wisdom about high inventories being necessary for a good delivery performance might be a myth when it comes to non-standardised items that are manufactured from varying raw materials. It thus could help supply chain managers in their argumentation with demanding sales colleagues.

Influence of Regioregularity on the Optoelectronic Properties of Conjugated Diketopyrrolopyrrole Polymers Comprising Asymmetric Monomers.

Two asymmetric thiophene (T)/pyridine (Py) flanked diketopyrrolopyrrole (DPP) polymers with a regiorandom and regioregular conjugated backbone are synthesized via a Stille polycondensation to investigate the effect of regioregularity on their optoelectronic properties and photovoltaic performance in fullerene-based polymer solar cells. Surprisingly, both polymers possess very similar optical bandgap, energy levels, and photovoltaic performance. These findings, combined with a factor of 19 reactivity difference between the two end groups of the asymmetric DPP monomer, intuitively suggest the formation of regular chain segments in the random polymer. However, by modeling the random polymerization reaction with a kinetic Monte Carlo (KMC) simulation, evidence is obtained for exclusive formation of a fully random polymer structure. UV–vis–NIR absorption spectra of three extended DPP chromophores, containing the donor segments (T-T-T, Py-T-Py, and Py-T-T) present in the regiorandom polymer, confirm that regioregularity of the backbone has a negligible influence on the optical properties.

Local distributions of the 1D dilute Ising model

The local distributions of the one-dimensional dilute annealed Ising model with charged impurities are studied. Explicit expressions are obtained for the pair distribution functions and correlation lengths, and their low-temperature asymptotic behavior is explored depending on the concentration of impurities. For a more detailed consideration of the ordering processes, we study local distributions. Based on the Markov property of the dilute Ising chain, we obtain an explicit expression for the probability of any finite sequence and find a geometric probability distribution for the lengths of sequences consisting of repeating blocks. An analysis of distributions shows that the critical behavior of the spin correlation length is defined by ferromagnetic or antiferromagnetic sequences, while the critical behavior of the impurity correlation length is defined by the sequences of impurities or by the charge-ordered sequences. For the dilute Ising chain, there are no other repeating sequences whose mean length diverges at zero temperature. While both the spin correlation and the impurity correlation lengths can diverge only at zero temperature, the ordering processes result in a maximum of the specific heat at finite temperature defined by the maximum rate of change of the impurity-spin pairs concentration. A simple approximate equation is found for this temperature. We show that the non-ordered dilute Ising chains correspond to the regular Markov chains, while various orderings generate the irregular Markov chains of different types.

Laser-induced regular nanostructure chains within microgrooves of Fe-based metallic glass

Femtosecond laser-induced surface structures have been extensively investigated over decades, however, their formation is not well controlled especially for the practical use in the photonic field. We here report the highly regular nanostructure formation within the grooves of the Fe-based metallic glass, upon irradiation of two temporally delayed femtosecond laser beams. For the case of micrometer-sized groove, multiple chains of spindle-like nanostructures are developed, with the spatial periods of 667 nm and 180 nm for the chain and spindle distributions, respectively. Their arrangement properties can be modulated by varying laser parameters. On the other hand, for the case of submicrometer-sized groove, there is only one chain of spindle-like nanostructures formed inside with the improved regular appearance. Two physical effects, including the plasmonic field generation from the groove edges and the surface magnon polariton excitation within the groove, are considered responsible for the phenomena, which consequently result in the spatial interlocking of two types of ripples. The theoretical analyses match well the experimental observations.

A Short Contribution to the Theory of Regular Chains

This paper contains short contributions to the theory of regular chains which follow a recent JSC paper by the same authors. These contributions apply to both the nondifferential and the differential context. They deal with the computation of normal forms and with the membership problem to ideals defined by regular chains.

Multifunctional Ni(II)-Based Metamagnetic Coordination Polymers for Electronic Device Fabrication.

The combination of two 8-aminoquinoline-based Schiff base ligands (L1 and L2) with SCN- and Ni(II) has led to the synthesis of two new one-dimensional thiocyanato-bridged coordination polymers: [Ni(L1)(NCS)2]n (1) and [Ni(L2)(NCS)2]n (2). Both compounds are isostructural and consists of regular zigzag thiocyanato-bridged chains with very weak S···S interchain interactions. The measured room-temperature conductivities of compounds 1 and 2 (7.0 × 10-5 and 2.0 × 10-5 S m-1, respectively) are indicative of semiconductor behavior which increases in the presence of photoillumination (3.5 × 10-4 and 4.9 × 10-4 S m-1, respectively). The measured I-V characteristics of compound 1 and 2 based thin film metal-semiconductor (MS) junction devices under irradiation and nonirradiation conditions show a nonlinear rectifying behavior, typical of a Schottky diode (SD). The rectification ratios (Ion/Ioff) of the SDs in the dark at ±2 V (26.96 and 31.96 for 1- and 2-based devices, respectively) increase to 44.19 and 79.42, respectively, upon light irradiation. The photoinduced behavior has been analyzed by thermionic emission theory, and to determine the diode parameters, the Cheung's method has been employed. These diode parameters indicate that compound 2 has a better performance in comparison to compound 1 and that these materials are good candidates for applications in electrochemical devices. Magnetic measurements show that both compounds present ferromagnetic Ni-Ni intrachain and weak antiferromagnetic interchain interactions. The isothermal magnetizations at 2 K show that both compounds are metamagnets with critical fields of ca. 130 mT in 1 and 90 mT in 2 at 2 K. In the ferromagnetic phase (above the critical field), both compounds exhibit a long-range ferromagnetic order with critical temperatures of around 3.5 K in 1 and 3.0 K in 2. DC and AC measurements with different applied DC fields confirm the metamagnetic behaviors and have allowed the determination of the magnetic phase diagram in both compounds.

Taiwan depository receipts forecasting along a novel regular Markov chain model

ABSTRACT This paper introduces a novel regular Markov chain model to forecast price trends in Taiwan Depository Receipts (TDRs), secondary listed companies in Taiwan. No studies of TDRs have used such a model. This research establishes a regular Markov chain model that identifies three levels: Rising more than average, rising less than average, and falling. The purpose of the proposed model is to integrate three levels of the rising quality with TDR’s settlement price on one trading day and the preceding day simultaneously. Thus, the methodology of this study is to introduce a 3*3-state regular Markov chain model, to use formulas to establish a Markov chain probability matrix, and to give a graphical representation for the proposed regular Markov chain model. The numerical result shows that, through a regular Markov chain model, the forecasting outcomes can provide investors with useful information, such as the long-term price of TDRs or whether or not the distribution of the states for the price of the TDRs will stabilize over time.

Asymmetric Open-Closed Dimer Mechanism of Polyhydroxyalkanoate Synthase PhaC.

SummaryBiodegradable polyester polyhydroxyalkanoate (PHA) is a promising bioplastic material for industrial use as a replacement for petroleum-based plastics. PHA synthase PhaC forms an active dimer to polymerize acyl moieties from the substrate acyl-coenzyme A (CoA) into PHA polymers. Here we present the crystal structure of the catalytic domain of PhaC from Chromobacterium sp. USM2, bound to CoA. The structure reveals an asymmetric dimer, in which one protomer adopts an open conformation bound to CoA, whereas the other adopts a closed conformation in a CoA-free form. The open conformation is stabilized by the asymmetric dimerization and enables PhaC to accommodate CoA and also to create the product egress path. The bound CoA molecule has its β-mercaptoethanolamine moiety extended into the active site with the terminal SH group close to active center Cys291, enabling formation of the reaction intermediate by acylation of Cys291.

Discrete time crystal in a finite chain of Rydberg atoms without disorder

We study the collective dynamics of a clean Floquet system of cold atoms, numerically simulating two realistic set-ups based on a regular chain of interacting Rydberg atoms driven by laser fields. In both cases, the population evolution and its Fourier spectrum display clear signatures of a discrete time crystal (DTC), exhibiting the appearance of a robust subharmonic oscillation which persists on a time scale increasing with the chain size, within a certain range of control parameters. We also characterize how the DTC stability is affected by dissipative processes, typically present in this atomic system even though the Rydberg state is very long lived.

Assessment of facility and health worker readiness to provide quality antenatal, intrapartum and postpartum care in rural Southern Nepal

BackgroundIncreased coverage of antenatal care and facility births might not improve maternal and newborn health outcomes if quality of care is sub-optimal. Our study aimed to assess the facility readiness and health worker knowledge required to provide quality maternal and newborn care.MethodsUsing an audit tool and interviews, respectively, facility readiness and health providers’ knowledge of maternal and immediate newborn care were assessed at all 23 birthing centers (BCs) and the District hospital in the rural southern Nepal district of Sarlahi. Facility readiness to perform specific functions was assessed through descriptive analysis and comparisons by facility type (health post (HP), primary health care center (PHCC), private and District hospital). Knowledge was compared by facility type and by additional skilled birth attendant (SBA) training.ResultsInfection prevention items were lacking in more than one quarter of facilities, and widespread shortages of iron/folic acid tablets, injectable ampicillin/gentamicin, and magnesium sulfate were a major barrier to facility readiness. While parenteral oxytocin was commonly provided, only the District hospital was prepared to perform all seven basic emergency obstetric and newborn care signal functions. The required number of medical doctors, nurses and midwives were present in only 1 of 5 PHCCs. Private sector SBAs had significantly lower knowledge of active management of third stage of labor and correct diagnosis of severe pre-eclampsia. While half of the health workers had received the mandated additional two-month SBA training, comparison with the non-trained group showed no significant difference in knowledge indicators.ConclusionsFacility readiness to provide quality maternal and newborn care is low in this rural area of Nepal. Addressing the gaps by facility type through regular monitoring, improving staffing and supply chains, supervision and refresher trainings is important to improve quality.

Differential Polymorphic Transformation Behavior of Polybutene-1 with Multiple Isotactic Sequences

For the solid-solid transformation from form II to form I of isotactic polybutene-1 (iPB), the temperature dependence of form I nucleation and growth was deemed to control the transformation process. However, the relationship between form I formation and form II disappearance in the transformation process is not clear. In this work, the spontaneous crystal transformation from form II to I of iPB with 81 mol% mmmm sequence concentration is studied firstly by tracking the two processes, the decay of form II and the yielding of form I in a wide range of temperature spanning from 0 °C to 50 °C and in a long transformation time ranging from 5 min to 65 days with in situ FTIR and WAXD. Unlike the literature reports, the decay rate of form II is firstly found to be lower than the yielding rate of form I at all studied temperatures, especially at low transition temperature. This is attributed to the amorphous chains which locate near crystal lamella participating into the nucleation of form II. The regular chain folding and growth of iPB form I from amorphous chains containing short isotactic sequences also lead to an increase in crystallinity of form I compared with that of initial form II crystallized at 60 °C. An increase in the annealing temperature results in decrease in crystallinity and increase in lamellae thickness of iPB form I.

Interpretations of the Tutte polynomials of regular matroids

A regular chain group N is the set of integral vectors orthogonal with rows of a matrix representing a regular matroid M, i.e., a totally unimodular matrix. N correspond to the set of flows and tensions if M is a graphic and cographic matroid, respectively. We evaluate the Tutte polynomial of M as number of pairs of specified elements of N.

On the Extended Hensel Construction and its application to the computation of real limit points

The Extended Hensel Construction (EHC) is a procedure which, for an input bivariate polynomial with complex coefficients, can serve the same purpose as the Newton-Puiseux algorithm, and, for the multivariate case, can be seen as an effective variant of Jung-Abhyankar Theorem. We show that the EHC requires only linear algebra and univariate polynomial arithmetic. We deduce complexity estimates and report on a software implementation together with experimental results. This work is motivated and illustrated by two applications. The first one is the computation of real branches of space curves. The second one is the computation of limits of real multivariate rational function.For the latter, we present an algorithm for determining the existence of the limit of a real multivariate rational function q at a given point p which is an isolated zero of the denominator of q. When the limit exists, the algorithm computes it, without making any assumption on the number of variables. A process, which extends the work of Cadavid, Molina and Vélez, reduces the multivariate setting to computing limits of bivariate rational functions. By using regular chain theory and triangular decomposition of semi-algebraic systems, we avoid the computation of singular loci and the decomposition of algebraic sets into irreducible components.

Fast-forward approach to adiabatic quantum dynamics of regular spin clusters: Nature of geometry-dependent driving interactions

The fast forward scheme of adiabatic quantum dynamics is applied to finite regular spin clusters with various geometries and the nature of driving interactions is elucidated. The fast forward is the quasi-adiabatic dynamics guaranteed by regularization terms added to the reference Hamiltonian, followed by a rescaling of time with use of a large scaling factor. With help of the regularization terms consisting of pair-wise and 3-body interactions, we apply the proposed formula (Phys. Rev.A 96, 052106(2017)) to regular triangle and open linear chain for N = 3 spin systems, and to triangular pyramid, square, primary star graph and open linear chain for N = 4 spin systems. The geometry-induced symmetry greatly decreases the rank of coefficient matrix of the linear algebraic equation for regularization terms. Choosing a transverse Ising Hamiltonian as a reference, we find: (1) for N = 3 spin clusters, the driving interaction consists of only the geometry-dependent pairwise interactions and there is no need for the 3-body interaction; (2) for N = 4 spin clusters, the geometry-dependent pair-wise interactions again constitute major part of the driving interaction, whereas the universal 3-body interaction free from the geometry is necessary but plays a subsidiary role. Our scheme predicts the practical driving interaction in accelerating the adiabatic quantum dynamics of structured regular spin clusters.

Modified Superexchange Model for Electron Tunneling Across the Terminated Molecular Wire

The modified superexchange model shows wide possibilities to clarify the mechanism of formation of a tunneling current through terminated molecular wire. The model has no inherent rigid restrictions of the standard superexchange model. This allows to obtain the analytical expressions for the analysis of the current–voltage characteristics of the wire, in which the voltage bias does not destroy the delocalzation of molecular orbitals belonging to the interior region of the wire. The conditions under which the modified superexchange model leads to the results that follow from the Simmons model of tunneling through a rectangular barrier, or the McConnell model of superexchange tunneling, are presented. The mechanism by which the wire's terminal units with the biased energies that do or do not resonate with the Fermi‐levels of the electrodes control the current, is clarified. Using an example of a molecular wire with a regular bridging alkane chain, it is shown that the model predicts current–voltage characteristics that are in good agreement with the experimental data on the attenuation of the tunneling current with an increase of the chain length.

Soluble Polyimides Bearing (cis, trans)-Hydrogenated Bisphenol A and (trans, trans)-Hydrogenated Bisphenol A Moieties: Synthesis, Properties and the Conformational Effect

In this work, hydrogenated bisphenol A (HBPA) based dinitro mixed isomers (1a′ and 1a) were synthesized and separated via vacuum distillation under the monitor of DSC and 1H NMR. Corresponding diamines (2a′ and 2a) were separately polycondensed with five commercial dianhydrides via a two-step thermal imidization to obtain PI-(1′-5′) and PI-(1-5). All the polyimides could afford flexible, tough, and transparent films, and most of them were readily soluble not only in common polar solvents like DMAc, but also in low boiling point solvents such as chloroform. 1H NMR spectra of the polyimides demonstrated that HBPA moiety showed no conformation changes during the preparation of polymers. For a given dianhydride, PI-(1-5) exhibited better thermal stability than that of PI-(1′-5′), this can be attributed that the equatorial, equatorial C–O in PI-(1-5) promoted denser and more regular molecular chain stacking, as can be evidenced by the WAXD and geometric optimization results. Additionally, when the dianhydride was ODPA, BPADA or 6FDA, no apparent difference was found in either the transmittance or solubility between two series of polyimides, which could be attributed that twisted and flexible ether linkages, as well as bulky substituents, led to the “already weakened” inter- and intramolecular CT interaction and cohesive force. However, when it came to rigid and stiff dianhydride, e.g., BPDA, PI-3′ took an obvious advantage over PI-3 in transmittance and solubility, which was possibly owed to the larger molecular chain d-spacing imparted by equatorial, axial C–O. An overall investigation of PI-(1′-5′) and PI-(1-5) on aspects of thermal, mechanical, morphological, soluble and optical performance values was carried out, and the conformation effects of HBPA isomers on the properties of two series of polyimides were discussed in detail.

Synthesis of precisely diphenyl ether-functionalized polyethylene via acyclic diene metathesis polymerization

We demonstrated the facile synthesis of a new class of functionalized polyethylene containing precisely sequenced diphenyl ether moieties via acyclic diene metathesis (ADMET) polymerization of a series of α, ω-diene monomers (M1-M3) with central diphenyl ether segments and subsequent exhaustive hydrogenation. 1H and 13C NMR spectroscopy have provided unambiguous evidence for precise primary architectures of the synthesized monomers and the resulting polymers. The thermal behaviors of all polymers were systematically investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results indicate that the introduction of diphenyl ether segments significantly enhanced the thermal stability of the polyethylenes. Ring-opening insertion metathesis polymerization (ROIMP) of M1-M3 with cis-cyclooctene was also performed, and after exhaustive hydrogenation, a series of irregularly sequenced copolymers with less regular chain structure and lower diphenyl ether content were yielded. Those copolymers possess a broad and ill-defined melting transition compared with the precisely-defined saturated homopolymers.

Identifying market risk for substandard and falsified medicines: an analytic framework based on qualitative research in China, Indonesia, Turkey and Romania

Introduction: Substandard and falsified medicines undermine health systems. We sought to unravel the political and economic factors which drive the production of these products, and to explain how they reach patients. Methods: We conducted in-depth case studies in China, Indonesia, Turkey and Romania. We reviewed academic papers and press reports (n = 840), developing semi-structured questionnaires. We interviewed regulators, policy-makers, pharmaceutical manufacturers, physicians, pharmacists, patients and academics (n=88). We coded data using NVivo software, and developed an analytic framework to assess national risks for substandard and falsified medicines. We tested the framework against cases reported to the World Health Organization, from countries at all income levels. Results: We found that increasing political commitment to provision of universal health coverage has led to public procurement policies aimed at lowering prices of medical products. In response, legitimate, profit-driven pharmaceutical companies protect their margins by cutting costs, or withdrawing from less profitable markets, while distributors engage in arbitrage. Meanwhile, health providers sometimes protect profits by 'upselling' patients to medicines not covered by insurers. Cost-cutting can undermine quality assurance, leading to substandard or degraded medicines. Other responses contribute to shortages, irrational demand and high prices. All of these provide market opportunities for producers of falsified products; they also push consumers outside of the regular supply chain, providing falsifiers with easy access to customers. The analytic framework capturing these interactions explained cases in most high and middle-income settings; additional factors operate in the poorest countries. Conclusions: Most efforts to secure medicine quality currently focus on product regulation. However, our research suggests market mechanisms are key drivers for poor quality medicines, including where political commitments to universal health coverage are under-resourced. We have developed a framework to guide country-specific, system-wide analysis. This can flag risks and pinpoint specific actions to protect medicine quality, and thus health.

Identifying market risk for substandard and falsified medicines: an analytic framework based on qualitative research in China, Indonesia, Turkey and Romania.

Introduction: Substandard and falsified medicines undermine health systems. We sought to unravel the political and economic factors which drive the production of these products, and to explain how they reach patients. Methods: We conducted in-depth case studies in China, Indonesia, Turkey and Romania. We reviewed academic papers and press reports (n = 840), developing semi-structured questionnaires. We interviewed regulators, policy-makers, pharmaceutical manufacturers, physicians, pharmacists, patients and academics (n=88). We coded data using NVivo software, and developed an analytic framework to assess national risks for substandard and falsified medicines. We tested the framework against cases reported to the World Health Organization, from countries at all income levels. Results: We found that increasing political commitment to provision of universal health coverage has led to public procurement policies aimed at lowering prices of medical products. In response, legitimate, profit-driven pharmaceutical companies protect their margins by cutting costs, or withdrawing from less profitable markets, while distributors engage in arbitrage. Meanwhile, health providers sometimes protect profits by 'upselling' patients to medicines not covered by insurers. Cost-cutting can undermine quality assurance, leading to substandard or degraded medicines. Other responses contribute to shortages, irrational demand and high prices. All of these provide market opportunities for producers of falsified products; they also push consumers outside of the regular supply chain, providing falsifiers with easy access to customers. The analytic framework capturing these interactions explained cases in most high and middle-income settings; additional factors operate in the poorest countries. Conclusions: Most efforts to secure medicine quality currently focus on product regulation. However, our research suggests market mechanisms are key drivers for poor quality medicines, including where political commitments to universal health coverage are under-resourced. We have developed a framework to guide country-specific, system-wide analysis. This can flag risks and pinpoint specific actions to protect medicine quality, and thus health.

The collective reserving model

This paper sets out a model for analysing claims development data, which we call the collective reserving model (CRM). The model is defined on the individual claim level and it produces separate IBNR and RBNS reserve estimators at the collective level without using any approximations. The CRM is based on ideas from a paper by Verrall, Nielsen and Jessen (VNJ) from 2010 in which a model is proposed that relies on a claim giving rise to a single payment. This is generalised by the CRM to the case of multiple payments per claim. All predictors of outstanding claims payments for the VNJ model are shown to hold for this new model. Moreover, the quasi-Poisson GLM estimation framework will be applicable as well, but without using an approximation. Furthermore, analytical expressions for the variance of the total outstanding claims payments are given, with a subdivision on IBNR and RBNS claims. To quantify the effect of allowing only one payment per claim, the model is related and compared to the VNJ model, in particular by looking at variance inequalities. The double chain ladder (DCL) method is discussed as an estimation method for this new model and it is shown that both the GLM- and DCL-based estimators are consistent in terms of an exposure measure. Lastly, both of these methods are shown to asymptotically reproduce the regular chain ladder reserve estimator when restricting predictions to the lower right triangle without the tail, motivating the chain ladder technique as a large-exposure approximation of this model.