Multiple multi-tier sustainable supply chain management: a social systems theory perspective

A multi-tier supply chain is a complex system as it covers a focal company and multiple tiers of suppliers in a complex supply chain network. This study explores the complexity in multi-tier sustainable supply chain management (SSCM) through a social systems theory perspective. We carried out a case study on IKEA China’s sustainable cotton initiative and examined its five cotton-textile supply chains. The primary data were collected through 22 semi-structured interviews with managers of IKEA China and their multi-tier suppliers. The findings suggest that in order to cope with environmental complexity in implementing multi-tier sustainable initiatives, focal companies tend to create both internal complexity and collaborative complexity in a variety of governance mechanisms. In addition, environmental overlap and available collaborative complexity increase in this process and can feed back into systems to facilitate further creation of requisite variety. We contribute to the multi-tier SSCM literature through providing an in-depth understanding of nuanced mechanisms of managing different tiers of suppliers to cope with complexities by adopting a social systems theory perspective. We also contribute to multi-tier supply chain governance mechanisms from an evolution perspective

IKEA: global sourcing and the sustainable leather initiative

The leather industry has traditionally been characterized by global operations across both developed and developing countries. Due to the long distance and contextual differences, there are numerous sustainability issues occurring along the global leather supply chain. Addressing these issues is both a responsibility and a challenge for multinational companies, especially in their global sourcing (GS) activities. This teaching case provides an example of implementing the sustainable leather initiative in the global sourcing process at IKEA. The case demonstrates IKEA’s sustainable leather initiative supported by its tailored GS strategy and GS structure and provides a benchmark of Sustainable GS for multinational companies and allows for a thorough discussion of how to implement a sustainability initiative while conducting GS. The case can be used to teach graduate/postgraduate in agricultural business, MBA and executive students on sustainable supply chain management and corporate social responsibility

The Sorting Index and Permutation Codes

In the combinatorial study of the coefficients of a bivariate polynomial that generalizes both the length and the reflection length generating functions for finite Coxeter groups, Petersen introduced a new Mahonian statistic $sor$, called the sorting index. Petersen proved that the pairs of statistics $(sor,cyc)$ and $(inv,rl\textrm{-}min)$ have the same joint distribution over the symmetric group, and asked for a combinatorial proof of this fact. In answer to the question of Petersen, we observe a connection between the sorting index and the B-code of a permutation defined by Foata and Han, and we show that the bijection of Foata and Han serves the purpose of mapping $(inv,rl\textrm{-}min)$ to $(sor,cyc)$. We also give a type $B$ analogue of the Foata-Han bijection, and we derive the quidistribution of $(inv_B,{\rm Lmap_B},{\rm Rmil_B})$ and $(sor_B,{\rm Lmap_B},{\rm Cyc_B})$ over signed permutations. So we get a combinatorial interpretation of Petersen's equidistribution of $(inv_B,nmin_B)$ and $(sor_B,l_B')$. Moreover, we show that the six pairs of set-valued statistics $\rm (Cyc_B,Rmil_B)$, $\rm(Cyc_B,Lmap_B)$, $\rm(Rmil_B,Lmap_B)$, $\rm(Lmap_B,Rmil_B)$, $\rm(Lmap_B,Cyc_B)$ and $\rm(Rmil_B,Cyc_B)$ are equidistributed over signed permutations. For Coxeter groups of type $D$, Petersen showed that the two statistics $inv_D$ and $sor_D$ are equidistributed. We introduce two statistics $nmin_D$ and $\tilde{l}_D'$ for elements of $D_n$ and we prove that the two pairs of statistics $(inv_D,nmin_D)$ and $(sor_D,\tilde{l}_D')$ are equidistributed.Comment: 25 page

Quantum enhancement of N-photon phase sensitivity by interferometric addition of down-converted photon pairs to weak coherent light

It is shown that the addition of down-converted photon pairs to coherent laser light enhances the N-photon phase sensitivity due to the quantum interference between components of the same total photon number. Since most of the photons originate from the coherent laser light, this method of obtaining non-classical N-photon states is much more efficient than methods based entirely on parametrically down-converted photons. Specifically, it is possible to achieve an optimal phase sensitivity of about delta phi^2=1/N^(3/2), equal to the geometric mean of the standard quantum limit and the Heisenberg limit, when the average number of down-converted photons contributing to the N-photon state approaches (N/2)^(1/2).Comment: 21 pages, including 6 figures. Extended version gives more details on down-conversion efficiencies and clarifies the relation between phase sensitivity and squeezing. The title has been changed in order to avoid misunderstandings regarding these concept