Relationship between petal abscission and programmed cell death in Prunus yedoensis and Delphinium belladonna

Depending on the species, the end of flower life span is characterized by petal wilting or by abscission of petals that are still fully turgid. Wilting at the end of petal life is due to programmed cell death (PCD). It is not known whether the abscission of turgid petals is preceded by PCD. We studied some parameters that indicate PCD: chromatin condensation, a decrease in nuclear diameter, DNA fragmentation, and DNA content per nucleus, using Prunus yedoensis and Delphiniumbelladonna which both show abscission of turgid petals at the end of floral life. No DNA degradation, no chromatin condensation, and no change in nuclear volume was observed in P. yedoensis petals, prior to abscission. In abscising D.belladonna petals, in contrast, considerable DNA degradation was found, chromatin was condensed and the nuclear volume considerably reduced. Following abscission, the nuclear area in both species drastically increased, and the chromatin became unevenly distributed. Similar chromatin changes were observed after dehydration (24 h at 60°C) of petals severed at the time of flower opening, and in dehydrated petals of Ipomoea nil and Petunia hybrida, severed at the time of flower opening. In these flowers the petal life span is terminated by wilting rather than abscission. It is concluded that the abscission of turgid petals in D. belladonna was preceded by a number of PCD indicators, whereas no such evidence for PCD was found at the time of P. yedoensis petal abscission. Dehydration of the petal cells, after abscission, was associated with a remarkable nuclear morphology which was also found in younger petals subjected to dehydration. This nuclear morphology has apparently not been described previously, for any organism

Proteomic analysis of pollination-induced corolla senescence in petunia

Senescence represents the last phase of petal development during which macromolecules and organelles are degraded and nutrients are recycled to developing tissues. To understand better the post-transcriptional changes regulating petal senescence, a proteomic approach was used to profile protein changes during the senescence of Petunia×hybrida ‘Mitchell Diploid’ corollas. Total soluble proteins were extracted from unpollinated petunia corollas at 0, 24, 48, and 72 h after flower opening and at 24, 48, and 72 h after pollination. Two-dimensional gel electrophoresis (2-DE) was used to identify proteins that were differentially expressed in non-senescing (unpollinated) and senescing (pollinated) corollas, and image analysis was used to determine which proteins were up- or down-regulated by the experimentally determined cut-off of 2.1-fold for P <0.05. One hundred and thirty-three differentially expressed protein spots were selected for sequencing. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to determine the identity of these proteins. Searching translated EST databases and the NCBI non-redundant protein database, it was possible to assign a putative identification to greater than 90% of these proteins. Many of the senescence up-regulated proteins were putatively involved in defence and stress responses or macromolecule catabolism. Some proteins, not previously characterized during flower senescence, were identified, including an orthologue of the tomato abscisic acid stress ripening protein 4 (ASR4). Gene expression patterns did not always correlate with protein expression, confirming that both proteomic and genomic approaches will be required to obtain a detailed understanding of the regulation of petal senescence

On-demand food delivery: a systematic literature review

Purpose: The purpose of this paper is twofold: first, to review the extant academic literature on on-demand food delivery (ODFD) services, i.e. the delivery of freshly prepared meals from restaurants to customers enabled by online platforms; second, to propose directions for future research in this field. Design/methodology/approach: This work reviews 59 papers published between 2016 and 2020. They are classified with respect to both their research methodology and the addressed themes, namely the actors involved and the activities creating value for the ODFD ecosystem. The latter was analysed by applying a framework derived from the integration of traditional models and literature about platforms/business ecosystems. Results were validated through interviews with practitioners. Findings: Due to its huge success and the significant complexities behind it, the ODFD business has been gaining the interest of academics. The authors’ review highlights that (1) the perspectives of the various actors involved should be integrated, moving towards an ecosystem-based view; (2) future research should focus more on restaurant operations and their role in ODFD systems and (3) despite they have been investigated by several academic contributions, human resource management and logistics of ODFD systems still present room for further extensions, in the areas of intervention/regulation and distribution network/batching, respectively. Originality/value: This review offers insights to both academics and practitioners. On the academic side, it analyses the literature on ODFD systems, outlining directions for future research. On the managerial side, it provides a comprehensive view on the most critical value-creating activities for ODFD businesses

Optimal in-store fulfillment policies for online orders in an omni-channel retail environment

The explosive growth of e-commerce creates a need for increasingly responsive omni-channel fulfillment capabilities, which raises new challenges in inventory management and order fulfillment for retailers. In response to these challenges, many retailers attempt to establish so-called ship-from-store concepts, which leverage their physical store networks to fulfill online orders. In this study, we analyze the optimal setup of these in-store fulfillment processes of online orders for an omni-channel retailer. We use a simulation-based approach combined with exploratory modeling to prescribe optimal fulfillment policies under a variety of sources of uncertainty. We apply our proposed model to a case study informed by real data from a leading sports fashion retailer in New York City in order to illustrate the practical applicability and value of our approach. Our results determine (i) the optimal amount of time to allow for batching of online orders prior to starting the in-store picking process; (ii) the optimal amount of time to allow for readily picked orders prior to starting the delivery process; (iii) the optimal number of pickers; and (iv) the optimal number of packers, and the related performance measures. Finally, we build on our analysis results to derive a set of managerial implications applicable to many omni-channel problems.</p

Route efficiency implications of time windows and vehicle capacities in first- and last-mile logistics

In this paper, we analyze the route efficiency effects that emerge from combining realistically constrained first-mile pickup and last-mile delivery operations into joint vehicle routes. Specifically, we examine (i) the individual effect of discrete, non-overlapping time window constraints; (ii) the individual effect of vehicle capacity constraints; and (iii) the joint impact of both constraint types on local route efficiency gains due to the integration of pickup and delivery operations. Extending the existent literature on continuum approximation of route distances, we propose closed-form adjustment factors which accurately capture these non-trivial route efficiency effects. To derive the adjustment factors, we conduct extensive numerical experiments and apply a novel hybrid data analysis approach which combines exploratory data analysis with symbolic regression. Our analysis suggests that these real-world constraints affect the optimal stop sequence and diminish or even eliminate the expected efficiency gains from integrating first- and last-mile operations. The proposed adjustment factors are particularly relevant for the optimal strategic design and operational planning of modern, industrial-scale distribution networks in light of growing and increasingly fragmented e-commerce volumes and a high cost pressure on the logistics industry. They help researchers and practitioners to efficiently quantify the expected benefits from integrating pickup and delivery operations, and to assess under which circumstances such an integration is (not) desirable.ISSN:0377-2217ISSN:1872-686

Optimal in-store fulfillment policies for online orders in an omni-channel retail environment

The explosive growth of e-commerce creates a need for increasingly responsive omni-channel fulfillment capabilities, which raises new challenges in inventory management and order fulfillment for retailers. In response to these challenges, many retailers attempt to establish so-called ship-from-store concepts, which leverage their physical store networks to fulfill online orders. In this study, we analyze the optimal setup of these in-store fulfillment processes of online orders for an omni-channel retailer. We use a simulation-based approach combined with exploratory modeling to prescribe optimal fulfillment policies under a variety of sources of uncertainty. We apply our proposed model to a case study informed by real data from a leading sports fashion retailer in New York City in order to illustrate the practical applicability and value of our approach. Our results determine (i) the optimal amount of time to allow for batching of online orders prior to starting the in-store picking process; (ii) the optimal amount of time to allow for readily picked orders prior to starting the delivery process; (iii) the optimal number of pickers; and (iv) the optimal number of packers, and the related performance measures. Finally, we build on our analysis results to derive a set of managerial implications applicable to many omni-channel problems.Policy Analysi