Periodic trends and easy estimation of relative stabilities in 11-vertex nido-p-block-heteroboranes and -borates

Density functional theory computations were carried out for 11-vertex nido-p-block-hetero(carba)boranes and -borates containing silicon, germanium, tin, arsenic, antimony, sulfur, selenium and tellurium heteroatoms. A set of quantitative values called “estimated energy penalties” was derived by comparing the energies of two reference structures that differ with respect to one structural feature only. These energy penalties behave additively, i.e., they allow us to reproduce the DFT-computed relative stabilities of 11-vertex nido-heteroboranes in general with good accuracy and to predict the thermodynamic stabilities of unknown structures easily. Energy penalties for neighboring heteroatoms (HetHet and HetHet′) decrease down the group and increase along the period (indirectly proportional to covalent radii). Energy penalties for a five- rather than four-coordinate heteroatom, [Het5k(1) and Het5k(2)], generally, increase down group 14 but decrease down group 16, while there are mixed trends for group 15 heteroatoms. The sum of HetHet′ energy penalties results in different but easily predictable open-face heteroatom positions in the thermodynamically most stable mixed heterocarbaboranes and -borates with more than two heteroatoms

Intrusion detection systems in cloud computing: a contemporary review of techniques and solutions

Rapid growth of resources and escalating cost of infrastructure is leading organizations to adopt cloud computing. Cloud computing provides high performance, efficient utilization, and on-demand availability of resources. However, the cloud environment is vulnerable to different kinds of intrusion attacks which involve installing malicious software and creating backdoors. In a cloud environment, where businesses have hosted important and critical data, the security of underlying technologies becomes crucial. To mitigate the threat to cloud environments, Intrusion Detection Systems (IDS) are a layer of defense. The aim of this survey paper is to review IDS techniques proposed for the cloud. To achieve this objective, the first step is defining the limitations and unique characteristics of each technique. The second step is establishing the criteria to evaluate IDS architectures. In this paper, the criteria used is derived from basic characteristics of cloud. Next step is a comparative analysis of various existing intrusion detection techniques against the criteria. The last step is on the discussion of drawbacks and open issues, comprehended from the evaluation, due to which implementation of IDS in cloud environment face hurdles

Response and recovery of grapevine to water deficit : from genes to physiology

International audienceGrapevine is a crop of global economic importance which is often cultivated in dry Mediterranean climates. In the context of climatic change, periods of drought could increase and become more intense. Growers will face increasing pressure to increase irrigation efficiently and/or adopt new grapevine varieties with increased drought resistance and water use efficiency. Adapting viticulture to these challenges requires an improved understanding of how grapevines behave under drought to enable sustainable management strategies and develop new varieties and rootstocks. This chapter summarizes our current understanding of the changes in physiology, signaling, metabolism, and gene expression that mediate grapevine’s response and adaptation to drought