Identification and Application of CLE Peptides for Drought Resistance in Solanaceae Crops.

The CLE (CLAVATA3/Embryo Surrounding Region-related) family, a group of peptides with hormone-like features, plays a pivotal role in plant growth, development, and adaptation to stress. Through homology-based blast analysis of 32 Arabidopsis thaliana CLE peptide sequences, we have identified 5, 14, and 10 CLE family members in Nicotiana tabacum, Capsicum annuum, and Solanum melongena, respectively. Chemical synthesis and functional assays of the peptides led to the discovery that NtCLE3 substantially enhances the drought resistance of these three Solanaceae crops. Our transcriptome, RT-qPCR, and antioxidant enzyme activity data showed that NtCLE3 increased antioxidant capacity and ABA synthesis in tobacco. Moreover, the recombinant protein RPNtCLE3, composed of 6*NtCLE3, preserved the capacity to foster drought resilience and proved to be a promising drought resistance regulator, which presents a more favorable alternative for field applications compared to ABA which degrades rapidly under sunlight exposure. This research unveils the prospective utility of NtCLE3 in enhancing drought tolerance in Solanaceae crops and provides new ideas for the development of novel bioregulators aimed at mitigating drought stress.

Autonomic end-to-end quality-of-service assurance over QKD-secured optical networks.

Quantum key distribution (QKD) provides future-proof security for data communications over optical networks. Currently, sophisticated QKD systems are developed and the scale of QKD-secured optical networks (QKD-ONs) becomes larger. Given the complex network conditions and dynamic end-to-end security services in QKD-ONs, autonomic management and control becomes a promising paradigm to support end-to-end quality-of-service (QoS) assurance in an efficient and stable way without requiring human intervention. Hence, to enable and utilize the autonomic functionalities over QKD-ONs for realizing the end-to-end QoS assurance becomes a challenge. This work enhances the software defined networking (SDN) technique to tackle this challenge because SDN can add programmability and flexibility for QKD-ON's management and control. A new architecture of SDN-based QKD-ONs supporting autonomic end-to-end QoS assurance is designed, where a knowledge engine with autonomic control loops is developed in the SDN controller. We present the autonomic end-to-end QoS assurance procedure, and the cross-layer collaborative QoS assurance (CLC-QA) strategy for implementing the autonomic functionalities in the network level over QKD-ONs. We also establish an experimental testbed of SDN-based QKD-ONs supporting autonomic end-to-end QoS assurance, and perform the numerical simulation to verify our proposed approaches. Experimental results demonstrate that our presented approaches can achieve the millisecond-level overall latency of 337 ms and 618 ms, during the first and second autonomic adjustment without human intervention in case of the autonomic QoS protection. Moreover, the CLC-QA strategy is evaluated under different traffic loads by being compared with the baseline strategy without cross-layer collaboration. It can improve 22.5% protection success ratio and save 5.7% average key consumption.

Developing a competency model for Chinese general practitioners: a mixed-methods study.

BACKGROUND: The Chinese government has formulated a series of policies and strengthened training of general practitioners (GPs) to support their role as "gatekeepers" of residents' health. This study aimed to explore the core competencies of Chinese GPs and develop a competency framework in line with China's actual conditions, which can provide a more scientific basis for the education, training, and evaluation of GPs. METHODS: Literature analysis and behaviour event interviews were conducted to build the competency dictionary and the initial version of the competency model. Two rounds of Delphi were performed to gain consensus on the final model. The questionnaire survey was carried out in 10 provinces (municipalities, autonomous regions) of China, and GPs were invited to score the importance of each competency item. The total sample was randomly divided into two groups. One group was for exploratory factor analysis (EFA), and the other was for confirmatory factor analysis (CFA) to examine the scale's reliability and validity. RESULTS: The dictionary of general practitioners' competency including 107 competency items was constructed. After two rounds of Delphi, a consensus was reached on 60 competencies in 6 domains. A total of 1917 valid questionnaires were obtained in the nationwide survey. The average importance score of all second-level indicators is 4.53 ± 0.45. The Cronbach's α coefficient is 0.984. The results of the five factors extracted by EFA showing the 68.16% cumulative explained variance variation is considered to be consistent with the six dimensions obtained by Delphi after thorough discussion. The model fitness indexes obtained by CFA were acceptable (χ2/df = 4.909, CFI = 0.869, NFI = 0.841, RMSEA = 0.065). The values of the composite reliability (CR) of the six dimensions were all greater than 0.7 (0.943, 0.927, 0.937, 0.927, 0.943, 0.950), and the average of variance extracted (AVE) were all greater than 0.5 (0.562, 0.613, 0.649, 0.563, 0.626, 0.635). The results showed that the model has good reliability and validity. CONCLUSION: A competency model for GPs suited to China has been developed, which may offer guidance for future training and medical licensing examinations of GPs.

Functional screening of the Arabidopsis 2C protein phosphatases family identifies PP2C15 as a negative regulator of plant immunity by targeting BRI1-associated receptor kinase 1.

Genetic engineering using negative regulators of plant immunity has the potential to provide a huge impetus in agricultural biotechnology to achieve a higher degree of disease resistance without reducing yield. Type 2C protein phosphatases (PP2Cs) represent the largest group of protein phosphatases in plants, with a high potential for negative regulatory functions by blocking the transmission of defence signals through dephosphorylation. Here, we established a PP2C functional protoplast screen using pFRK1::luciferase as a reporter and found that 14 of 56 PP2Cs significantly inhibited the immune response induced by flg22. To verify the reliability of the system, a previously reported MAPK3/4/6-interacting protein phosphatase, PP2C5, was used; it was confirmed to be a negative regulator of PAMP-triggered immunity (PTI). We further identified PP2C15 as an interacting partner of BRI1-associated receptor kinase 1 (BAK1), which is the most well-known co-receptor of plasma membrane-localized pattern recognition receptors (PRRs), and a central component of PTI. PP2C15 dephosphorylates BAK1 and negatively regulates BAK1-mediated PTI responses such as MAPK3/4/6 activation, defence gene expression, reactive oxygen species bursts, stomatal immunity, callose deposition, and pathogen resistance. Although plant growth and 1000-seed weight of pp2c15 mutants were reduced compared to those of wild-type plants, pp2c5 mutants did not show any adverse effects. Thus, our findings strengthen the understanding of the mechanism by which PP2C family members negatively regulate plant immunity at multiple levels and indicate a possible approach to enhance plant resistance by eliminating specific PP2Cs without affecting plant growth and yield.

Structure and functional divergence of PIP peptide family revealed by functional studies on PIP1 and PIP2 in Arabidopsis thaliana.

PAMP-induced secreted peptide (PIP), one of the small post-translationally modified peptides (PTMPs), plays a crucial role in plant development and stress tolerance. However, little is known about functional divergence among this peptide family. Here, we studied the evolution of the PIP family in 23 plant species (10 monocotyledons and 13 dicotyledons from 7 families) and their functional divergence in Arabidopsis. A total of 128 putative PIP precursors were identified and classified into two subfamilies through phylogenetic analysis. Functional studies on AtPIP1 which represents Clade I family and AtPIP2 which represents Clade II family have shown that AtPIP2 displayed stronger immunity induction activity but weaker root growth inhibition than AtPIP1 in Arabidopsis. Transcriptome analysis of Arabidopsis seedlings treated with AtPIP1 and AtPIP2 showed that differential genes for both polypeptides were significantly enriched in similar plant defense pathways. However, Co-expression and Protein-protein interaction (PPI) analysis showed that the functions of AtprePIP2 co-expressed genes were more enriched in plant defense pathways than AtprePIP1. Molecular docking results show that AtPIP1 binds to RLK7 receptor with a more stable free energy and less binding area than AtPIP2, while hydrogen bond transfer occurs at the SGP motif position. The above results suggest that the PIP family have undergone functional divergence during evolution. Collectively, this work illustrates the relationship between PIP structure and function using Arabidopsis PIP as an example, and provides new insights into the current understanding between growth inhibition and immune responses which may be correlated but not fully coupled.

Topology Abstraction-Based Routing Scheme for Secret-Key Provisioning in Hybrid GEO/LEO Quantum Satellite Networks.

Quantum key distribution (QKD) is a promising technique to resist the threat against quantum computers. However, the high loss of quantum signals over a long-distance optical fiber is an obstacle for QKD in the intercontinental domain. In this context, the quantum satellite network is preferred over the terrestrial quantum optical network. Due to the mobility of satellites, the satellite topology is dynamic in the quantum satellite network, which remains a challenge for routing. In hybrid geostationary-earth-orbit (GEO)/low-earth-orbit (LEO) quantum satellite networks, the lack of an efficient scheduling scheme for GEO/LEO satellites also limits the construction of quantum satellite networks. Therefore, this paper provides a topology abstraction-based routing scheme for secret-key provisioning, where the dynamic physical topology is translated into a quasi-static abstracted topology. This scheme contributes to saving the precious secret key resources. In order to improve the success probability of long-distance QKD requests, three novel resource-scheduling heuristic algorithms are proposed in hybrid GEO/LEO quantum satellite networks. Simulation results indicate that the proposed algorithms can improve the success probability of QKD requests by 47% compared to the benchmark.

Conservation and divergence of flg22, pep1 and nlp20 in activation of immune response and inhibition of root development.

Many pattern-recognition receptors (PRRs) and their corresponding ligands have been identified. However, it is largely unknown how similar and different these ligands are in inducing plant innate immunity and affecting plant development. In this study, we examined three well characterized ligands in Arabidopsis thaliana, namely flagellin 22 (flg22), plant elicitor peptide 1 (pep1) and a conserved 20-amino-acid fragment found in most necrosis and ethylene-inducing peptide 1-like proteins (nlp20). Our quantitative analyses detected the differences in amplitude in the early immune responses of these ligands, with nlp20-induced responses typically being slower than those mediated by flg22 and pep1. RNA sequencing showed the shared differentially expressed genes (DEGs) was mostly enriched in defense response, whereas nlp20-regulated genes represent only a fraction of those genes differentially regulated by flg22 and pep1. The three elicitors all inhibited primary root growth, especially pep1, which inhibited both auxin transport and signaling pathway. In addition, pep1 significantly inhibited the cell division and genes involved in cell cycle. Compared with flg22 and nlp20, pep1 induced much stronger expression of its receptor in roots, suggesting a potential positive feedback regulation in the activation of immune response. Despite PRRs and their co-receptor BAK1 were necessary for both PAMP induced immune response and root growth inhibition, bik1 mutant only showed impaired defense response but relatively normal root growth inhibition, suggesting BIK1 acts differently in these two biological processes.

Comparative transcriptome analysis revealed the molecular mechanism of the effect of light intensity on the accumulation of rhynchophylline and isorhynchophylline in Uncaria rhynchophylla.

Rhynchophylline (RIN) and isorhynchophylline (IRN), the main medicinal components in plant Uncaria rhynchophylla, have potential effects on Alzheimer's disease. Understanding the influence of environmental factors, especially light intensity, on the production of these active ingredients will help to improve cultivation techniques. Compared with the 100% light intensity (CK), the contents of RIN and IRN in U. rhynchophylla leaves significantly increased at 20% light intensity (HS) after 7 and 21 days. Short-term shading (21d) changed some morphological indicators of U. rhynchophylla, but did not affect its biomass. Transcriptome profile analysis was performed on data from two groups (7 and 21 days) of CK and HS samples and yielded 79,817 unigenes with an average length of 1023 bp. Concurrently, 2391 and 2136 differentially expressed genes were identified in the transcriptome data for, respectively, 7 and 21 days of shade treatment. Notably, unigenes known to be involved upstream in the biosynthesis of RIN and IRN, such as G8O, IO, 7-DLGT, LAMT, TDC, and STR, were mostly upregulated. In addition, 1065 putative transcription factors (TFs) were identified and grouped into 55 TF families; 26 TFs showed differential expression in the shade treatment after 7 and 21 days. HY5 and PIFs, two important TFs of the light signaling pathway, also showed differential expression. This study provides insight into how gene expression was affected by light intensity during RIN and IRN accumulation in U. rhynchophylla. Supplementary Information: The online version contains supplementary material available at 10.1007/s12298-022-01142-2.

Optimization of factors affecting the rooting of pine wilt disease resistant Masson pine (Pinus massoniana) stem cuttings.

Pine wilt disease (PWD) is a devastating disease affecting trees belonging to the genus Pinus. To control the spread of PWD in the Masson pine forest in China, PWD resistant Masson pine clones have been selected by the Anhui Academy of Forestry. However, because Masson pine is a difficult-to-root species, producing seedlings is challenging, especially from trees older than 5 years of age, which impedes the application of PWD resistant clones. In this study, we investigated the factors affecting rooting of PWD resistant clones and established a cheap, reliable, and simple method that promotes rooting. We tested the effects of three management methods, four substrates, two cutting materials, two cutting treatments, and three collection times on the rooting of cuttings obtained from 9-year-old PWD resistant clones. Rooting was observed only in stem cuttings treated with the full-light automatic spray management method. Additionally, stem cuttings showed a significantly higher rooting rate and root quality than needles cuttings. Compared with other substrates, stem cuttings planted in perlite produced the longest adventitious root and the highest total root length and lateral root number. Moreover, stem cuttings of PWD resistant clones collected in May showed a significantly higher rooting rate and root quality than those collected in June and July. Moreover, stem cuttings prepared with a horizontal cut while retaining the needles showed significantly higher rooting rate and root quality than those prepared with a diagonal cut while partly removing the needles. This study promotes the reproduction of seedlings of PWD-resistant Masson pine clones which helps control the spread of PWD, meanwhile, provides a technical reference for the propagation of mature pine trees via cuttings.

Multi-path-based quasi-real-time key provisioning in quantum-key-distribution enabled optical networks (QKD-ON).

With its information-theoretic security, quantum-key-distribution-enabled optical networks (QKD-ON) have become a promising candidate for future optical networks. The concept of quantum key pool (QKP) was introduced to offer an effective strategy for storing quantum keys. However, with the loss on its theoretical security due to storing these keys, balancing the storage of quantum keys and the security requirements of QKD-ONs poses a major challenge in their practical deployments. Hence, in this paper a concept of quasi-real-time key provisioning (QRT-KP) is introduced to address the tradeoff between quantum key storage and the degree of security. To satisfy the practical deployment of QRT-KP and the requirement of high-traffic flow, we propose a multi-path based QRT-KP (MP-QRT-KP) algorithm. Simulation results show that the MP-QRT-KP effectively enhances the performance of QKD-ONs in different scenarios, and it turns out that the algorithm performs better than single-path based QRT-KP (SP-QRT-KP) in terms of the success probability of key-allocation requests and key-resources utilization.

Dynamic secret-key provisioning in quantum-secured passive optical networks (PONs).

Quantum cryptography (QC) is currently under investigation to build highly secure optical communication networks. QC requires distribution of quantum keys (also called "secret" keys) on separate wavelength channels than those used to transmit the encrypted data. Hence, we propose a quantum-secured passive optical network (QS-PON) that supports both i) the traditional wavelength channels for secured data transmission, and ii) a quantum key distribution network (QKDN) running on separate dedicated wavelengths. The QKDN generates and stores secret keys that are then assigned to users' demands served on traditional PON channels. To generate secret keys, quantum transmitters at the optical network units (ONUs) exchange qubits with a quantum receiver at the optical line terminal (OLT). Then, the generated secret keys are stored in quantum key pools (QKPs) installed at both OLT and the ONUs and assigned to users' demands. Point-to-multipoint QKD systems have been experimentally demonstrated over various forms of quantum access networks (QANs), showing that an efficient mechanism to generate and assign quantum keys based on traffic requests is a critical component of QANs. In this study, we present a new QS-PON architecture, and we propose a dynamic secret-key provisioning (DSKP) algorithm that effectively generates and assigns secret keys from users' demands. Our proposed DSKP algorithm features two phases, the lowest-first secret-key generation (LF-SKG) phase and the hierarchical-clustering secret-key consumption (HC-SKC) phase. In this study, we also provide an analytical model that describes how secret keys are generated and consumed in QKPs. In our illustrative numerical evaluation, we compare our algorithm for secret-key provisioning with a baseline IPACT-based solution in terms of service-rejection ratio, time-slot utilization, and guard- and relay-time saving. Results show that DSKP reduces service-rejection ratio and guard- and relay-time of about 16% and 39.54%, respectively.

The Mediating Role of Hope in the Relationship Between Perceived Stress and Post-Traumatic Stress Disorder Among Chinese Patients with Oral Cancer: A Cross-Sectional Study.

PURPOSE: Cancer diagnosis and treatment are long-term traumatic stressors. Depression and anxiety are known to be prevalent in patients with cancer, but post-traumatic disorder (PTSD) has been overlooked frequently in this population. This study aimed to estimate the prevalence of PTSD and examined the mediating role of hope in the relationship between perceived stress and PTSD symptoms in Chinese patients with oral cancer. METHODS: A total of 230 oral cancer patients were recruited to complete a questionnaire including the Posttraumatic Stress Checklist-Civilian Version (PCL-C), the Perceived Stress Scale-10 (PSS-10) and the Herth Hope Index (HHI). Analysis of variances (ANOVA)/t-test, Person's r and hierarchical linear regression analysis methods were conducted to assess the associations among perceived stress, hope and PTSD symptoms. Asymptotic and resampling strategies were used to explore the mediating role of hope. RESULTS: The prevalence of PTSD symptoms was 6.05% in Chinese patients with oral cancer. Perceived stress was positively related to PTSD symptoms, explaining 39.9% of the variance. In addition, hope was negatively related to PTSD symptoms, explaining 5.9% of the variance. Besides, the proportion of mediation of hope was 30.06%. CONCLUSION: Perceived stress was positively associated with PTSD symptoms, and hope was negatively associated with PTSD symptoms. Furthermore, hope played partial mediating role in the relationship between perceived stress and PTSD symptoms. Thus, more attention should be paid to patients' PTSD status, and take measures is to relieve stress and increase hope.

Auxiliary graph based routing, wavelength, and time-slot assignment in metro quantum optical networks with a novel node structure.

Nowadays, critical sectors in government, finance, and military are facing increasingly high security challenges. However, traditional public-key crypto-systems based on computational complexity are likely to suffer from upgrade computational power. Quantum key distribution (QKD) is a promising technology to effectively address the challenge by providing secret keys due to the laws of quantum physics. Limited by the transmission distance of quantum communications, remote parties have to share secret keys by exchanging keys through the trusted relay nodes hop by hop. However, if relaying hop by hop is still used in metro quantum-optical networks (MQON), a large amount of key resources will be wasted since the distance between any two nodes is short. Therefore, the problem of how to distribute quantum keys with lower waste of key resources over MQON is urgent. In order to solve this problem, we design a novel quantum node structure that is able to bypass itself. Also, by extending the connectivity graph, auxiliary graphs are constructed to describe the adjacency of quantum nodes in different levels influenced by the physical distance. Based on the novel node, two routing, wavelength and time-slot assignment algorithms are proposed, in which some middle nodes can be bypassed to reduce the resource consumption as long as the distance between the two parties meets the requirement of quantum key distribution. Simulations have been conducted to verify the performance of the proposed algorithms in terms of blocking probability, resource utilization, number of bypassed nodes, and security rate per service. Numerical results illustrate that our algorithms perform better on resource utilization than a traditional scheme without bypass. Furthermore, a tradeoff between the keys saved and blocking probability is analyzed and discussed in our paper.

SNHG6 modulates oxidized low-density lipoprotein-induced endothelial cells injury through miR-135a-5p/ROCK in atherosclerosis.

BACKGROUND: Plenty of long non-coding RNAs (lncRNAs) play vital roles in the progression of atherosclerosis. Small nucleolar RNA host gene 6 (SNHG6) is a well known lncRNA that is aberrantly high expressed in atherosclerosis patients. However, its function and basic mechanism in atherosclerosis events have not been well clarified. METHODS: The expression patterns of SNHG6, miR-135a-5p, ROCK1 and ROCK2 in clinical samples and cells were detected by RT-qPCR assays. Cell Counting Kit-8 (CCK-8), flow cytometry assays, ELISA and reactive oxygen species (ROS) and malondialdehyde (MDA) detection, were performed to assess cell viability, apoptosis, inflammation and oxidative stress, respectively. Western blot analysis was carried out to examine the protein levels of Bax, Bcl-2, and SNHG6. Luciferase reporter and RIP assays were used to confirm the true interaction between SNHG6 and miR-135a-5p, or miR-135a-5p and ROCK. RESULTS: The levels of SNHG6, ROCK1 and ROCK2 were notably increased and miR-135a-5p was decreased in atherosclerosis patients and oxidized low-density lipoprotein (ox-LDL)-treated HUVECs. Knockdown of SNHG6 alleviated ox-LDL-induced injury of HUVECs, while this effect was partly reversed by miR-135a-5p inhibitor. Moreover, overexpression of ROCKs aggravated miR-135a-5p-alleviated atherosclerosis cell injury. SNHG6 contributed to ROCK expression through sequestering miR-135a-5p as a molecular sponge. CONCLUSION: SNHG6 functions as a promoter in atherosclerosis events by targeting miR-135a-5p/ROCK axis in ox-LDL-stimulated HUVECs. This finding will help to develop a novel therapeutic strategy for atherosclerosis.

Vps15 is critical to mediate autophagy in AngII treated HUVECs probably by PDK1/PKC signaling pathway.

AIMS: Vps15 is an important regulator on the activity of class III PI3K in autophagy induction. AngII plays a positive role of autophagy in the early protection of endothelial cells. In this study, the expression of Vps15 was knocked down using the specific shRNA to investigate the effects of Vps15 on cell autophagy, senescence and apoptosis in HUVECs stimulated by AngII. The associated cell signaling pathway was also explored. MATERIALS AND METHODS: MDC staining was applied to show autophagic bodies. Cell senescence was detected using ß-galactosidase staining. Cell apoptosis was examined by flow cytometry using Annexin V-FITC/PI staining. And western blot was used to evaluate the ratio of LC3-II/I and the activation of associated cell signaling pathway. KEY FINDINGS: Cell autophagy induced by AngII was inhibited in HUVECs transfected with Vps15-shRNA, while cell senescence and apoptosis were enhanced. Rescue experiment revealed that cell autophagy was activated after Vps15 reexpression, while cell senescence and apoptosis were inhibited. Moreover, the phosphorylations of PDK1 and PKC substrates were increased after AngII treatment, which were decreased by Vps15 knockdown. Pretreatment of cells with the inhibitor for PDK1 or PKC attenuated cell autophagy after AngII stimulation, yet promoted cell senescence and apoptosis. The phosphorylations of both PDK1 and PKC were inhibited in cells pretreated with PDK1 inhibitor. Only the activation of PKC was inhibited when the inhibitor for pan-PKC was used. SIGNIFICANCE: These results suggested that Vps15 was critical to the protective autophagy in HUVECs induced by AngII, and PDK1/PKC signaling pathway was probably involved.

Joint balancing of IT and spectrum resources for selecting virtualized network function in inter-datacenter elastic optical networks.

With network functions decoupled from specific hardware, network function virtualization (NFV) is a promising technology to accelerate service provisioning in datacenter (DC) networks. In inter-datacenter elastic optical networks, each virtualized network function (VNF) is usually deployed in multiple DCs for the sake of survivability. In service provisioning, different VNF selections greatly affect IT resources in DCs as well as spectrum resources in optical networks. This paper investigates how to select appropriate VNFs for service requests to achieve joint load balancing of IT and spectrum resources. Two joint balancing factors are proposed to quantify the impact of different VNF selections on network load. Furthermore, a Joint-Optimization Selection (JOS) algorithm is designed to select VNFs in a joint load balancing manner. The performance of the proposed algorithm is evaluated in terms of resource utilization, blocking probability and average path length. Simulation results indicate that the proposed algorithm outperforms the benchmark algorithm.

Dirty-data-based alarm prediction in self-optimizing large-scale optical networks.

Machine-learning-based solutions are showing promising results for several critical issues in large-scale optical networks. Alarm (caused by failure, disaster, etc.) prediction is an important use-case, where machine learning can assist in predicting events, ahead of time. Accurate prediction enables network administrators to undertake preventive measures. For such alarm prediction applications, high-quality data sets for training and testing are crucial. However, the collected performance and alarm data from large-scale optical networks are often dirty, i.e., these data are incomplete, inconsistent, and lack certain behaviors or trends. Such data are likely to contain several errors, when collected from old-fashioned optical equipment, in particular. Even after appropriate data preprocessing, feature distribution can be extremely unbalanced, limiting the performance of machine learning algorithms. This paper demonstrates a Dirty-data-based Alarm Prediction (DAP) method for Self-Optimizing Optical Networks (SOONs). Experimental results on a commercial large-scale field topology with 274 nodes and 487 links demonstrate that the proposed DAP method can achieve high accuracy for different types of alarms.

Crosstalk-aware spectrum defragmentation by re-provisioning advance reservation requests in space division multiplexing enabled elastic optical networks with multi-core fiber.

Space division multiplexing enabled elastic optical networks (SDM-EONs) with multi-core fiber (MCF) have become a promising candidate for future optical transport networks, due to their high capacity and flexibility. Meanwhile, driven by the development of cloud computing and data centers, more types of requests are allowed in the networks, i.e., the usual immediate reservation (IR) requests, which need to be served immediately, and advance reservation (AR) requests, which support initial-delay tolerance services. However, with the introduction of AR requests, spectrum fragments occur frequently in both spatial and time dimension as lightpaths are set up and torn down, and the issue of spectrum fragmentation could be much more serious in SDM-EONs than in simple EONs. To measure fragments status in both spatial and time dimension in SDM-EONs, we first design a metric, i.e., time-dimensional spectrum compactness (TSC). Then, based on TSC, we propose a crosstalk-aware AR requests re-provisioning algorithm with two strategies to optimize the fragments in SDM-EONs. The performance of the proposed algorithm is evaluated via software simulation in terms of spectrum compactness, blocking probability, spectrum utilization, average moving times, average re-provisioning latency and average start time delay. The results show that the proposed re-provisioning algorithm can effectively improve spectrum compactness and spectrum efficiency of the networks. We also evaluate the proposed re-provisioning algorithm in different TSC thresholds, and it turns out that the proposed re-provisioning algorithm in higher threshold performs better in terms of spectrum compactness and spectrum utilization.

SDQaaS: software defined networking for quantum key distribution as a service.

Quantum key distribution (QKD) holds the potential of providing long-term integrity and confidentiality for data and communications. Currently, many fiber-based QKD systems have been commercialized and several QKD networks have been deployed. Given the high cost and complexity of QKD network deployment, QKD as a service (QaaS) becomes a promising pattern for future QKD networks. The QaaS concept is that multiple users can apply for QKD services to obtain their required secret-key rates (SKRs) from the same QKD network infrastructure instead of deploying their dedicated QKD networks. Accordingly, how to provide efficient and flexible QaaS for fulfilling the SKR requirements of multiple users over a QKD network infrastructure becomes a new challenge. This study introduces the software defined networking (SDN) technique to overcome this challenge, since SDN can add flexibility together with efficient QKD network management. A new framework of SDN for QaaS (SDQaaS) is proposed, where the QaaS functions are developed in the SDN controller. We present the protocol extension, intercommunication workflow, and routing and SKR assignment strategy for QaaS implementation in the SDQaaS framework. We also establish a SDQaaS experimental testbed and perform the numerical simulation to verify our presented approaches. Experimental results demonstrate that our presented approaches can achieve efficient and flexible QaaS over the QKD network. Moreover, simulation results indicate that the success probability of QKD service requests can be increased via lowering the flexibility of SKR requirements for QKD service creation, sacrificing more cost to produce higher SKR over the QKD network, or gradually reducing SKR requirements with the modification of QKD service.