1,835 research outputs found
Engineering Advanced Training Environment for Crisis Management: The Pandora Project
The paper describes the technical framework of a near real-life training environment for learning activities suitable for training in crisis scenarios. The underlying architecture features a design that makes provision for a learning environment capable of training collaborative, as well as independent, decision making skills among crisis managers in potential crisis situations. Modelling the training scenarios takes into consideration both the pragmatic nature of responding to crisis, as well as the human behavioural factors involved in dealing with situations of chaos and uncertainty. This work is part of ongoing research on the Pandora1 project, which aims to provide a near-real training environment at affordable cost
Superconducting Quantum Point contacts and Maxwell Potential
The quantization of the current in a superconducting quantum point contact is
reviewed and the critical current is discussed at different temperatures
depending on the carrier concentration as well by suggesting a constant
potential in the semiconductor and then a Maxwell potential. When the Fermi
wave length is comparable with the constriction width we showed that the
critical current has a step-like variation as a function of the constriction
width and the carrier concentration.Comment: 13 pages, 8 figures, some figures are clarified; scheduled to appear
in an issue in MPLB Vo.21, (2007
Isolation of avian influenza H5N1 virus from vaccinated commercial layer flock in Egypt
Uninterrupted transmission of highly pathogenic avian influenza virus (HPAIV)
H5N1 of clade 2.2.1 in Egypt since 2006 resulted in establishment of two main
genetic clusters. The 2.2.1/C group where all recent human and majority of
backyard origin viruses clustered together, meanwhile the majority of viruses
derived from vaccinated poultry in commercial farms grouped in 2.2.1.1 clade.
In the present investigation, an HPAIV H5N1 was isolated from twenty weeks old
layers chickens that were vaccinated with a homologous H5N1 vaccine at 1, 7
and 16 weeks old. At twenty weeks of age, birds showed cyanosis of comb and
wattle, decrease in egg production and up to 27% mortality. Examined serum
samples showed low antibody titer in HI test (Log2 3.2 ± 4.2). The
hemagglutinin (HA) and neuraminidase (NA) genes of the isolated virus were
closely related to viruses in 2.2.1/C group isolated from poultry in live bird
market (LBM) and backyards or from infected people. Conspicuous mutations in
the HA and NA genes including a deletion within the receptor binding domain in
the HA globular head region were observed. Despite repeated vaccination of
layer chickens using a homologous H5N1 vaccine, infection with HPAIV H5N1
resulted in significant morbidity and mortality. In endemic countries like
Egypt, rigorous control measures including enforcement of biosecurity, culling
of infected birds and constant update of vaccine virus strains are highly
required to prevent circulation of HPAIV H5N1 between backyard birds,
commercial poultry, LBM and humans
Concurrent Acquisition of a Single Nucleotide Polymorphism in Diverse Influenza H5N1 Clade 2.2 Sub-clades
Highly pathogenic Influenza A H5N1 was first identified in Guangdong Province in 1996, followed by human cases in Hong Kong in 1997 1,2. The number of confirmed human cases now exceeds 300 and the associated Case Fatality Rate exceeds 60% 3. The genetic diversity of the serotype continues to increase. Four distinct clades or sub-clades have been linked to human cases 4-7. The gradual genetic changes identified in the sub-clades have been attributed to copy errors by viral encoded polymerases that lack an editing function, thereby resulting in antigenic drift 8. We report here the concurrent acquisition of the same polymorphism by multiple, genetically distinct, clade 2.2 sub-clades in Egypt, Russia, Kuwait, and Ghana. These changes are not easily explained by the current theory of “random mutation” through copy error, and are more easily explained by recombination with a common source. The recombination role is further supported by the high fidelity replication in swine influenza 9 and aggregation of single nucleotide polymorphisms in H5N1 clade 2.2 hemagglutinin 10
Concurrent Acquisition of a Single Nucleotide Polymorphism in Diverse Influenza H5N1 Clade 2.2 Sub-clades
Highly pathogenic Influenza A H5N1 was first identified in Guangdong Province in 1996, followed by human cases in Hong Kong in 1997. The number of confirmed human cases now exceeds 300, and the associated Case Fatality Rate exceeds 60%. The genetic diversity of the serotype continues to increase. Four distinct clades or sub-clades have been linked to human cases. The gradual genetic changes identified in the sub-clades have been attributed to copy errors by viral encoded polymerases that lack an editing function, thereby resulting in antigenic drift. We report here the concurrent acquisition of the same polymorphism by multiple, genetically distinct, clade 2.2 sub-clades in Egypt, Russia, and Ghana. These changes are not easily explained by the current theory of “random mutation” through copy error, and are more easily explained by recombination with a common source. This conclusion is supported by additional polymorphisms shared by clade 2.2 isolates in Egypt and Germany
NAD(P)H:quinone oxidoreductase 1 inducer activity of some novel anilinoquinazoline derivatives
The Kelch-like ECH-associated protein 1 (Keap1)/nuclear factor erythroid 2-related factor 2 (Nrf2)/antioxidant response elements pathway enables cells to survive oxidative stress conditions through regulating the expression of cytoprotective enzymes such as NAD(P)H:quinone oxidoreductase 1 (NQO1). This work presents the design and synthesis of novel anilinoquinazoline derivatives (2–16a) and evaluation of their NQO1 inducer activity in murine cells. Molecular docking of the new compounds was performed to assess their ability to inhibit Keap1–Nrf2 protein–protein interaction through occupying the Keap1–Nrf2-binding domain, which leads to Nrf2 accumulation and enhanced gene expression of NQO1. Docking results showed that all compounds can potentially interact with Keap1; however, 1,5-dimethyl-2-phenyl-4-(2-phenylquinazolin-4-ylamino)-1,2-dihydropyrazol-3-one (9), the most potent inducer, showed the largest number of interactions with key amino acids in the binding pocket (Arg483, Tyr525, and Phe478) compared to the native ligand or any other compound in this series
Aggregation of Single Nucleotide Polymorphisms in a Human H5N1 Clade 2.2 Hemagglutinin
The evolution of H5N1 has attracted significant interest 1-4 due to linkages with avian 5,6 and human infections 7,8. The basic tenets of influenza genetics 9 attribute genetic drift to replication errors caused by a polymerase complex that lacks a proof reading function. However, recent analysis 10 of swine influenza genes identifies regions copied with absolute fidelity for more than 25 years. In addition, polymorphism tracing of clade 2.2 H5N1 single nucleotide polymorphisms identify concurrent acquisition 11 of the same polymorphism onto multiple genetic backgrounds in widely dispersed geographical locations. Here we show the aggregation of regional clade 2.2 polymorphisms from Germany, Egypt, and sub-Sahara Africa onto a human Nigerian H5N1 hemagglutinin (HA), implicating recombination in the dispersal and aggregation of single nucleotide polymorphisms from closely related genomes
Aggregation of Single Nucleotide Polymorphisms in a Human H5N1 Clade 2.2 Hemagglutinin
The rapid evolution of the H5N1 serotype of avian influenza has been explained by a mechanism involving the selection of single nucleotide polymorphisms generated by copy errors. The recent emergence of H5N1 Clade 2.2 in fifty countries, offered a unique opportunity to view the acquisition of new polymorphism in these evolving genomes. We analyzed the H5N1 hemagglutinin gene from a fatal human case from Nigeria in 2007. The newly emerged polymorphisms were present in diverse H5N1 isolates from the previous year. The aggregation of these polymorphisms from clade 2.2 sub-clades was not supported by recent random mutations, and was most easily explained by recombination between closely related sequences
Exploiting Inter- and Intra-Memory Asymmetries for Data Mapping in Hybrid Tiered-Memories
Modern computing systems are embracing hybrid memory comprising of DRAM and
non-volatile memory (NVM) to combine the best properties of both memory
technologies, achieving low latency, high reliability, and high density. A
prominent characteristic of DRAM-NVM hybrid memory is that it has NVM access
latency much higher than DRAM access latency. We call this inter-memory
asymmetry. We observe that parasitic components on a long bitline are a major
source of high latency in both DRAM and NVM, and a significant factor
contributing to high-voltage operations in NVM, which impact their reliability.
We propose an architectural change, where each long bitline in DRAM and NVM is
split into two segments by an isolation transistor. One segment can be accessed
with lower latency and operating voltage than the other. By introducing tiers,
we enable non-uniform accesses within each memory type (which we call
intra-memory asymmetry), leading to performance and reliability trade-offs in
DRAM-NVM hybrid memory. We extend existing NVM-DRAM OS in three ways. First, we
exploit both inter- and intra-memory asymmetries to allocate and migrate memory
pages between the tiers in DRAM and NVM. Second, we improve the OS's page
allocation decisions by predicting the access intensity of a newly-referenced
memory page in a program and placing it to a matching tier during its initial
allocation. This minimizes page migrations during program execution, lowering
the performance overhead. Third, we propose a solution to migrate pages between
the tiers of the same memory without transferring data over the memory channel,
minimizing channel occupancy and improving performance. Our overall approach,
which we call MNEME, to enable and exploit asymmetries in DRAM-NVM hybrid
tiered memory improves both performance and reliability for both single-core
and multi-programmed workloads.Comment: 15 pages, 29 figures, accepted at ACM SIGPLAN International Symposium
on Memory Managemen
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