23 research outputs found
An exploration of the determinants for decision to migrate existing resources to cloud computing using an integrated TOE-DOI model
Migrating existing resources to cloud computing is a strategic organisational decision that can be difficult. It requires the consideration and evaluation of a wide range of technical and organisational aspects. Although a significant amount of attention has been paid by many industrialists and academics to aid migration decisions, the procedure remains difficult. This is mainly due to underestimation of the range of factors and characteristics affecting the decision for cloud migration. Further research is needed to investigate the level of effect these factors have on migration decisions and the overall complexity. This paper aims to explore the level of complexity of the decision to migrate the cloud. A research model based on the diffusion of innovation (DOI) theory and the technology-organization-environment (TOE) framework was developed. The model was tested using exploratory and confirmatory factor analysis. The quantitative analysis shows the level of impact of the identified variables on the decision to migrate. Seven determinants that contribute to the complexity of the decisions are identified. They need to be taken into account to ensure successful migration. This result has expanded the collective knowledge about the complexity of the issues that have to be considered when making decisions to migrate to the cloud. It contributes to the literature that addresses the complex and multidimensional nature of migrating to the cloud
The effect of plant extracts as seed treatments to control bacterial leaf spot of tomato in Tanzania
Changes in soil organic matter under different land management in misiones province (Argentina) Mudanças na matéria orgânica edafica sob diferentes manejos de solo na província de misiones (Argentina)
Highly weathered tropical soils rapidly loose soil organic matter (SOM) and may be affected by water erosion and soil compaction after deforestation and intensive cultivation. With the main objective to estimate the SOM balances in a subtropical soil we determined the dynamics of SOM in a degraded yerba mate (Ilex paraguaiensis Saint Hil.) plantation introduced after deforestation and with elephant grass (Pennisetum purpureum L.) as a cover crop. The study site was in Misiones, Argentina, and we use the natural 13C abundance methodology and a descriptive model. The study was conducted on three contiguous 50 x 100 m plots of a typic Kandihumult soil with: (i) native forest, (ii) 50 years of continuous yerba mate monoculture with intensive tillage, and (iii) yerba mate associated with elephant grass as a cover crop and no tillage. We determined bulk density, carbon (C), nitrogen (N) and 13C content of the soil (0 - 0.05, 0.05 - 0.15 m layers) and the grass biomass. Yerba mate monoculture reduced soil C and N content as well as porosity at 0 - 0.15 m depth by 43 and 23%, respectively, as compared to the native forest. After ten years of yerba mate - elephant grass association soil C and N contents at the same depth increased by 19 and 12%, respectively, compared to the yerba mate monoculture, while soil porosity remained similar. Total C input,13C, and soil organic C were incorporated into a three compartment model to evaluate elephant grass C dynamics. Through the natural 13C abundance methodology we tracked the elephant grass C incorporation and the "old" soil C loss, and determined the model parameters - humification (k1) and mineralization (k) coefficients and stable C (Cs)- unambiguously. The high k1 and k predicted by the model are probably explained by elephant grass root system incorporation under no tillage and humid subtropical climate, respectively. In soil under yerba mate monoculture, Cs was counted as 91% of the total soil organic C.<br>Os solos altamente intemperizados dos trópicos perdem rapidamente matéria orgânica do solo (SOM) e podem ser afetados pela erosão hídrica e compactação depois de seu deflorestamento e agricultura contínua. O objetivo foi determinar a dinâmica da matéria orgânica do solo com capim-elefante (Pennisetum purpureum L.) em um Kandihumult da província de Misiones (Argentina) após desmatamento e cultivo contínuo de erva-mate (Ilex paraguaiensis Saint Hil.), utilizando a metodologia da abundância natural em carbono 13 (13C) e um modelo descritivo. O estudo foi conduzido em três parcelas contíguas de 50 x 100 m. As situações comparadas foram: (a) floresta nativa, e (b) local com 50 anos de monocultivo intensivo de erva- mate, e (c) erva-mate associada com capim-elefante como cultivo de cobertura sob plantio direto. Determinaram-se os conteúdos de carbono (C), de nitrogênio (N) e de 13C e a densidade aparente do solo (camadas 0 - 0,05 e 0.05 - 0,15 m) e a biomassa da gramínea. Depois de 50 anos de monocultivo de erva-mate, os conteúdos de C e N e a porosidade da camada 0 - 0,15 m da floresta nativa diminuíram em 42, 47 e 23%, respectivamente. Depois de 10 anos de associação erva-mate - capim-elefante, os conteúdos de C e N do solo e na mesma profundidade aumentaram em relação ao monocultivo de erva-mate em 19 e 12%, respectivamente, mas a porosidade não foi modificada. O aporte de C, o 13C e o C orgânico total do solo foram incorporados em um modelo de três compartimentos para avaliar a dinâmica do C proveniente do capim-elefante. A metodologia da abundância natural em 13C permitiu traçar a incorporação do C proveniente do capim-elefante e a perda do C "velho" no solo, e determinar sem ambigüidade os parâmetros do modelo: coeficiente de humificação (k1), coeficiente de mineralização da fração ativa de C (k) e o C estável (Cs). Os altos valores de k1 e k preditos pelo modelo foram atribuídos à alta contribuição do sistema radicular do capim-elefante sob plantio direto e ao clima subtropical úmido, respectivamente. No solo sob monocultivo de erva-mate, Cs representou 91% do C orgânico total do solo
pH-Responsive Nanoparticle Vaccines for Dual-Delivery of Antigens and Immunostimulatory Oligonucleotides
Protein subunit vaccines offer important potential advantages over live vaccine vectors, but generally elicit weaker and shorter-lived cellular immune responses. Here we investigate the use of pH-responsive, endosomolytic polymer nanoparticles that were originally developed for RNA delivery as vaccine delivery vehicles for enhancing cellular and humoral immune responses. Micellar nanoparticles were assembled from amphiphilic diblock copolymers composed of an ampholytic core-forming block and a re-designed polycationic corona block doped with thiol-reactive pyridyl disulfide groups to enable dual-delivery of antigens and immunostimulatory CpG oligodeoxynucleotide (CpG ODN) adjuvants. Polymers assembled into 23 nm particles with simultaneous packaging of CpG ODN and a thiolated protein antigen, ovalbumin (ova). Conjugation of ova to nanoparticles significantly enhanced antigen cross-presentation in vitro relative to free ova or an unconjugated, physical mixture of the parent compounds. Subcutaneous vaccination of mice with ova-nanoparticle conjugates elicited a significantly higher CD8(+) T cell response (0.5% IFN-ɣ(+) of CD8(+)) compared to mice vaccinated with free ova or a physical mixture of the two components. Significantly, immunization with ova-nanoparticle conjugates electrostatically complexed with CpG ODN (dual-delivery) enhanced CD8(+) T cell responses (3.4% IFN-ɣ(+) of CD8(+)) 7-, 18-, and 8-fold relative to immunization with conjugates, ova administered with free CpG, or a formulation containing free ova and CpG complexed to micelles, respectively. Similarly, dual-delivery carriers significantly increased CD4(+)IFN-ɣ(+) (Th1) responses, and elicited a balanced IgG1/IgG2c antibody response. Intradermal administration further augmented cellular immune responses, with dual-delivery carriers inducing ~7% antigen-specific CD8(+) T cells. This work demonstrates the ability of pH-responsive, endosomolytic nanoparticles to actively promote antigen cross-presentation and augment cellular and humoral immune responses via dual-delivery of protein antigens and CpG ODN. Hence, pH-responsive polymeric nanoparticles offer promise as a delivery platform for protein subunit vaccines