Making the most of game theory in the supplier selection process for complex items

There has been a growing interest in the application of game-theory to enhance the impact of supplier selection processes, but existing applications have been focused on commodity products. Therefore, scholars have recently called for further research into the use of game-theory to develop supplier selection processes for more complex products. The aim of this paper is to contribute by discussing the design and implementation of a novel supplier selection process based on game-theory through an empirical study of a construction project for an automotive company. The novelty of this research stems from the application of game-theory to design and implement a two-phase supplier selection process, combining a modified Japanese-auction with a structured bargaining process, and evaluating its impact in the context of complex items. Findings suggest that two-phase processes can enhance the effectiveness of the supplier selection by increasing competition and generating better predictions of the outcomes from the negotiation

Modulation of folic acid bioaccessibility by encapsulation in pH-responsive gated mesoporous silica particles

[EN] A study on the controlled release of folic acid (FA) from pH-responsive gated mesoporous silica particles (MSP) is reported. The MCM-41 support was synthesized using tetraethyl orthosilicate (TEOS) as hydrolytic inorganic precursor and the surfactant hexadecyltrimethylammonium bromide (CTAB) as porogen species. Calcination of the mesostructured phase resulted in the starting solid. This solid was loaded with FA to obtain the initial support S0. Moreover, this FA-loaded material was further functionalized with 3-[2-(2-aminoethylamino)ethylamino]propyltrimethoxysilane (N3) in order to obtain the gated polyamine-functionalised material S1. Solids S0 and S1 were characterized using standard solid state procedures. It was found that the functionalization process and the inclusion of FA on the pores did not modify the mesoporous structure of the starting material. FA delivery studies in water with solids S0 and S1 were carried out in water at pH 2 and 7.5. S0 was not able to completely inhibit FA delivery at acidic pH yet a rapid FA release at neutral pH was observed in few minutes. In contrast, S1 was tightly capped at pH 2 and displayed a sustained delivery of FA when the pH was switched to 7.5. In the second part of the study, FA loading and functionalization of S1-like supports was optimized. In particular, solids loaded with FA in phosphate buffered saline (PBS) and capped with N3 in acetate buffer at pH 2 exhibited a delivery capacity up to 95 μg FA/mg solid. Finally, FA release from the selected optimized supports was studied following an in vitro digestion procedure. The results showed that amine-capped MSP were not only able to hinder the release of the vitamin in gastric fluids (pH 2), but were also capable of deliver progressively the FA in presence of a simulated intestinal juice (pH 7.5) offering a suitable mechanism to control the bioaccessibility of the vitaminAuthors gratefully acknowledge the financial support from the Ministerio de Economia y Competitividad (Projects AGL201239597-C02 and MAT2012-38429-004-01) and the Generalitat Valenciana (project PROMETEO/2009/016). E.P. is grateful to the Ministerio de Ciencia e Innovacion for his Grant (AP2008-00620). C.C. thanks the Generalitat Valenciana for her post-doctoral contract VALi+D.Pérez-Esteve, É.; Fuentes López, A.; Coll Merino, MC.; Acosta, C.; Bernardos Bau, A.; Amoros Del Toro, PJ.; Marcos Martínez, MD.... (2015). Modulation of folic acid bioaccessibility by encapsulation in pH-responsive gated mesoporous silica particles. Microporous and Mesoporous Materials. 202:124-132. https://doi.org/10.1016/j.micromeso.2014.09.049S12413220

Polymer Composites Containing Gated Mesoporous Materials for On-Command Controlled Release

Polyamidic nanofibrous membranes containing gated silica mesoporous particles, acting as carriers, are described as novel hybrid composite materials for encapsulation and on-command delivery of garlic extracts. The carrier system consists of MCM-41 solids functionalized in the outer surface, with linear polyamines (solid P1) and with hydrolyzed starch (solid P2), both acting as molecular gates. Those particles were adsorbed on electospun nylon-6 nanofibrous membranes yielding to composite materials M1 and M2. FE-SEM analysis confirmed the presence of particles incorporated on the nylon nanofibers. The release of the entrapped molecules (garlic extract) from the P1, P2, M1, and M2 materials was evaluated using cyclic voltammetry measurements. Electrochemical studies showed that at acidic pH P1 and M1 were unable to release their entrapped cargo (closed gate), whereas at neutral pH both materials release their loading (open gate). Dealing with P2 and M2 materials, in the absence of pancreatin a negligible release is observed (closed gate), whereas in the presence of enzyme the load is freely to diffuse to the solution. These newly developed composite nanomaterials, provide a homogeneous easy-to-handle system with controlled delivery and bioactive-protective features, having potential applications on pharmacology, medical and engineering fields.The authors wish to express their gratitude to the Generalitat Valenciana (Grisolia scholarship 2011/012, project PROM-ETEO/2009/016), Spanish Government (MINECO Projects AGL2012-39597-C02-01, AGL2012-39597-C02-02 and MAT2012-38429-C04-01) and the CIBER-BBN for their support. IILA thanks DISTAM and Universita degli di Milano for a specialization scholarship. We would also like to thank the Institut de Ciencia dels Materials (ICMUV) and to the Microscopy Service of the Universitat Politecnica de Valencia for technical support. We thank Roquette for the Glucidex samples.Acosta Romero, C.; Pérez Esteve, E.; Fuenmayor, CA.; Benedetti, S.; Cosio, MS.; Soto Camino, J.; Sancenón Galarza, F.... (2014). Polymer Composites Containing Gated Mesoporous Materials for On-Command Controlled Release. ACS Applied Materials and Interfaces. 6(9):6453-6460. https://doi.org/10.1021/am405939y645364606

The Repeating Flaring Activity of Blazar AO 0235+164

Context. Blazar AO 0235+164, located at redshift z = 0.94, has undergone several sharp multi-spectral-range flaring episodes during the last decades. In particular, the episodes peaking in 2008 and 2015, that received extensive multi-wavelength coverage, exhibited interesting behavior. Aims. We study the actual origin of these two observed flares by constraining the properties of the observed photo-polarimetric variability, those of the broad-band spectral energy-distribution and the observed time-evolution behavior of the source as seen by ultra-high resolution total-flux and polarimetric Very-long-baseline interferometry (VLBI) imaging. Methods. The analysis of VLBI images allows us to constrain kinematic and geometrical parameters of the 7 mm jet. We use the Discrete Correlation Function to compute the statistical correlation and the delays between emission at different spectral ranges. Multi-epoch modeling of the spectral energy distributions allows us to propose specific models of emission; in particular for the unusual spectral features observed in this source in the X-ray region of the spectrum during strong multi spectral-range flares. Results. We find that these X-ray spectral features can be explained by an emission component originating in a separate particle distribution than the one responsible for the two standard blazar bumps. This is in agreement with the results of our correlation analysis that do not find a strong correlation between the X-rays and the remaining spectral ranges. We find that both external Compton dominated and synchrotron self-Compton dominated models can explain the observed spectral energy distributions. However, synchrotron self-Compton models are strongly favored by the delays and geometrical parameters inferred from the observations

Notch and Wnt Signaling Mediated Rod Photoreceptor Regeneration by Müller Cells in Adult Mammalian Retina

Background: Evidence emerging from a variety of approaches used in different species suggests that Müller cell function may extend beyond its role of maintaining retinal homeostasis to that of progenitors in the adult retina. Enriched Müller cells in vitro or those that re-enter cell cycle in response to neurotoxin-damage to retina in vivo display multipotential and self-renewing capacities, the cardinal features of stem cells. Methodology/Principal Findings: We demonstrate that Notch and Wnt signaling activate Müller cells through their canonical pathways and that a rare subset of activated Müller cells differentiates along rod photoreceptor lineage in the outer nuclear layer. The differentiation of activated Müller cells along photoreceptor lineage is confirmed by multiple approaches that included Hoechst dye efflux analysis, genetic analysis using retina from Nrl-GFP mice, and lineage tracing using GS-GFP lentivirus in wild type and rd mice in vitro and S334ter rats in vivo. Examination of S334ter rats for head-neck tracking of visual stimuli, a behavioral measure of light perception, demonstrates a significant improvement in light perception in animals treated to activate Müller cells. The number of activated Müller cells with rod photoreceptor phenotype in treated animals correlates with the improvement in their light perception. Conclusion/Significance: In summary, our results provide a proof of principle for non-neurotoxin-mediated activation o

Polarized blazar X-rays imply particle acceleration in shocks

Most of the light from blazars, active galactic nuclei with jets of magnetized plasma that point nearly along the line of sight, is produced by high-energy particles, up to around 1 TeV. Although the jets are known to be ultimately powered by a supermassive black hole, how the particles are accelerated to such high energies has been an unanswered question. The process must be related to the magnetic field, which can be probed by observations of the polarization of light from the jets. Measurements of the radio to optical polarization—the only range available until now—probe extended regions of the jet containing particles that left the acceleration site days to years earlier1,2,3, and hence do not directly explore the acceleration mechanism, as could X-ray measurements. Here we report the detection of X-ray polarization from the blazar Markarian 501 (Mrk 501). We measure an X-ray linear polarization degree ΠX of around 10%, which is a factor of around 2 higher than the value at optical wavelengths, with a polarization angle parallel to the radio jet. This points to a shock front as the source of particle acceleration and also implies that the plasma becomes increasingly turbulent with distance from the shock

X-ray Polarization Observations of BL Lacertae

Blazars are a class of jet-dominated active galactic nuclei with a typical double-humped spectral energy distribution. It is of common consensus the Synchrotron emission to be responsible for the low frequency peak, while the origin of the high frequency hump is still debated. The analysis of X-rays and their polarization can provide a valuable tool to understand the physical mechanisms responsible for the origin of high-energy emission of blazars. We report the first observations of BL Lacertae performed with the Imaging X-ray Polarimetry Explorer ({IXPE}), from which an upper limit to the polarization degree $\Pi_X<$12.6\% was found in the 2-8 keV band. We contemporaneously measured the polarization in radio, infrared, and optical wavelengths. Our multiwavelength polarization analysis disfavors a significant contribution of proton synchrotron radiation to the X-ray emission at these epochs. Instead, it supports a leptonic origin for the X-ray emission in BL Lac.Comment: 17 pages, 5 figures, accepted for publication in ApJ

Discovery of X-ray polarization angle rotation in active galaxy Mrk 421

The magnetic field conditions in astrophysical relativistic jets can be probed by multiwavelength polarimetry, which has been recently extended to X-rays. For example, one can track how the magnetic field changes in the flow of the radiating particles by observing rotations of the electric vector position angle $\Psi$. Here we report the discovery of a $\Psi_{\mathrm x}$ rotation in the X-ray band in the blazar Mrk 421 at an average flux state. Across the 5 days of Imaging X-ray Polarimetry Explorer (IXPE) observations of 4-6 and 7-9 June 2022, $\Psi_{\mathrm x}$ rotated in total by $\geq360^\circ$. Over the two respective date ranges, we find constant, within uncertainties, rotation rates ($80 \pm 9$ and $91 \pm 8 ^\circ/\rm day$) and polarization degrees ($\Pi_{\mathrm x}=10\%\pm1\%$). Simulations of a random walk of the polarization vector indicate that it is unlikely that such rotation(s) are produced by a stochastic process. The X-ray emitting site does not completely overlap the radio/infrared/optical emission sites, as no similar rotation of $\Psi$ was observed in quasi-simultaneous data at longer wavelengths. We propose that the observed rotation was caused by a helical magnetic structure in the jet, illuminated in the X-rays by a localized shock propagating along this helix. The optically emitting region likely lies in a sheath surrounding an inner spine where the X-ray radiation is released

Game Theory and Purchasing Management: An Empirical Study of Auctioning in the Automotive Sector

Part 5: Operations Management in Engineer-to-Order ManufacturingInternational audienceThe purchasing function is assuming an increasingly relevant role within companies in the last decades, taking over the main responsibility for the costs of goods purchased as well as for supplier management. Its relevancy is due to the fact that purchasing can contribute to develop competitive advantages by aligning its strategy to the business strategy. Purchasing strategy is usually deployed per (purchasing) category and operationally executed in the so called tactical purchasing process. One key step is the negotiation/bidding where there is a lack of empirical research regarding the application of game theory. This paper contributes by discussing how game theory can be systematically utilised for designing negotiations (i.e. games) and getting more efficient results –by presenting an empirical study on automotive sector company, specifically on a bidding process for constructing a new production facility in Mexico

Alignment of the Purchasing Strategy to the Business Strategy: An Empirical Study on a Harbour Cranes Company

Part 1: Knowledge-Based Performance ImprovementInternational audienceThe purchasing function is assuming an increasingly relevant role within companies in the last decades. This is due to a fact that purchasing strategy can contribute to develop competitive advantages. Therefore, it is important to align the purchasing strategy with the company business strategy. On the other hand, category management can be used as the basic unit of strategic purchasing analysis, which measures the competitive improvement in purchasing management. It its known that a differentiated purchasing strategy involves managing suppliers within the different categories, so that, it is considered that there should be a leadership to level category by purchasing managers to improve the company competitiveness. Hence, this paper contributes by presenting how aligned business and purchasing strategies and product categorization leads to increased competitiveness –by presenting an empirical study on a harbor cranes company