377 research outputs found
DeepPR: Progressive Recovery for Interdependent VNFs with Deep Reinforcement Learning
The increasing reliance upon cloud services entails more flexible networks
that are realized by virtualized network equipment and functions. When such
advanced network systems face a massive failure by natural disasters or
attacks, the recovery of the entire system may be conducted in a progressive
way due to limited repair resources. The prioritization of network equipment in
the recovery phase influences the interim computation and communication
capability of systems, since the systems are operated under partial
functionality. Hence, finding the best recovery order is a critical problem,
which is further complicated by virtualization due to dependency among network
nodes and layers. This paper deals with a progressive recovery problem under
limited resources in networks with VNFs, where some dependent network layers
exist. We prove the NP-hardness of the progressive recovery problem and
approach the optimum solution by introducing DeepPR, a progressive recovery
technique based on Deep Reinforcement Learning (Deep RL). Our simulation
results indicate that DeepPR can achieve the near-optimal solutions in certain
networks and is more robust to adversarial failures, compared to a baseline
heuristic algorithm.Comment: Technical Report, 12 page
Preliminary Examination of the System Fly Ash-Bottom Ash-Flue Gas Desulphurization Gypsum-Portland Cement-Water for Road Construction
This paper describes an investigation into the use of three power plant wastes: fly ash, flue gas desulphurization gypsum, and bottom ash for subbase layers in road construction. Two kinds of mixtures of these wastes with Portland cement and water were made: first with fly ash consisting of coarser particles (<1.651 mm) and second with fly ash consisting of smaller particles (<0.42 mm). The mass ratio of fly ash-Portland cement-flue gas desulphurization gypsum-bottom ash was the same (3 : 1 : 1 : 5) in both mixtures. For both mixtures, the compressive strength, the mineralogical composition, and the leaching characteristics were determined at different times, 7 and 28 days, after preparation. The obtained results showed that both mixtures could find a potential use for subbase layers in road construction
On the implementation of a recently proposed dosimetric formalism to a robotic radiosurgery system
The aim of this work is to implement a recently proposed dosimetric formalism for nonstandard fields to the calibration and small field output factor measurement of a robotic stereotactic radiosurgery system
Viral Small Interfering RNAs Target Host Genes to Mediate Disease Symptoms in Plants
The Cucumber mosaic virus (CMV) Y-satellite RNA (Y-Sat) has a
small non-protein-coding RNA genome that induces yellowing symptoms in infected
Nicotiana tabacum (tobacco). How this RNA pathogen induces
such symptoms has been a longstanding question. We show that the yellowing
symptoms are a result of small interfering RNA (siRNA)-directed RNA silencing of
the chlorophyll biosynthetic gene, CHLI. The CHLI mRNA contains a 22-nucleotide
(nt) complementary sequence to the Y-Sat genome, and in Y-Sat-infected plants,
CHLI expression is dramatically down-regulated. Small RNA sequencing and
5′ RACE analyses confirmed that this 22-nt sequence was targeted for mRNA
cleavage by Y-Sat-derived siRNAs. Transformation of tobacco with a RNA
interference (RNAi) vector targeting CHLI induced Y-Sat-like symptoms. In
addition, the symptoms of Y-Sat infection can be completely prevented by
transforming tobacco with a silencing-resistant variant of the CHLI gene. These
results suggest that siRNA-directed silencing of CHLI is solely responsible for
the Y-Sat-induced symptoms. Furthermore, we demonstrate that two
Nicotiana species, which do not develop yellowing symptoms
upon Y-Sat infection, contain a single nucleotide polymorphism within the
siRNA-targeted CHLI sequence. This suggests that the previously observed species
specificity of Y-Sat-induced symptoms is due to natural sequence variation in
the CHLI gene, preventing CHLI silencing in species with a mismatch to the Y-Sat
siRNA. Taken together, these findings provide the first demonstration of small
RNA-mediated viral disease symptom production and offer an explanation of the
species specificity of the viral disease
Seroprevalence of SARS-CoV-2 antibodies among primary healthcare workers in the Republic of Srpska, Bosnia & Herzegovina: A cross-sectional study
Healthcare workers (HCW) in primary healthcare centres in the Republic of Srpska, Bosnia and Herzegovina, are on the first combat line with COVID-19. This study aimed to assess the seroprevalence of SARS-CoV-2 among HCW at the primary healthcare centres and to analyse the risk exposure to COVID-19, clinical signs and vaccination status. A cross-sectional study was conducted among HCW at the selected primary healthcare centres between 19 March and 30 April 2021. Antibodies against the SARS-CoV-2 virus were detected by enzyme-linked immunosorbent assay (ELISA). A total of 1,023 HCW (mean age 45 years; 71% female) were included in the study. The anti-SARS-CoV-2 antibodies were detected in 69.5% of all participants. There was a significant difference in seropositivity among primary healthcare centres from different geographical regions. As many as 432 (42%) of all participants had confirmed COVID-19 symptoms before the study and, 84.8% of them were seropositive. This study showed that 702 primary HCW were vaccinated with any of these vaccines: Sputnik V, Sinopharm, Pfizer/Biontech. High titre of SARS-CoV-2 antibodies was found amongst those who received one (92.6%) or both (97.2%) doses of vaccines. In this study, we report high prevalence of SARS-CoV-2 antibody among HCW in primary healthcare in the Republic of Srpska, Bosnia and Herzegovina during the third pandemic wave
Carbon Dynamics, Development and Stress Responses in Arabidopsis: Involvement of the APL4 Subunit of ADP-Glucose Pyrophosphorylase (Starch Synthesis)
An Arabidopsis thaliana T-DNA insertional mutant was identified and characterized for enhanced tolerance to the singlet-oxygen-generating herbicide atrazine in comparison to wild-type. This enhanced atrazine tolerance mutant was shown to be affected in the promoter structure and in the regulation of expression of the APL4 isoform of ADP-glucose pyrophosphorylase, a key enzyme of the starch biosynthesis pathway, thus resulting in decrease of APL4 mRNA levels. The impact of this regulatory mutation was confirmed by the analysis of an independent T-DNA insertional mutant also affected in the promoter of the APL4 gene. The resulting tissue-specific modifications of carbon partitioning in plantlets and the effects on plantlet growth and stress tolerance point out to specific and non-redundant roles of APL4 in root carbon dynamics, shoot-root relationships and sink regulations of photosynthesis. Given the effects of exogenous sugar treatments and of endogenous sugar levels on atrazine tolerance in wild-type Arabidopsis plantlets, atrazine tolerance of this apl4 mutant is discussed in terms of perception of carbon status and of investment of sugar allocation in xenobiotic and oxidative stress responses
Transcriptome Analysis of the Arabidopsis Megaspore Mother Cell Uncovers the Importance of RNA Helicases for Plant Germline Development
Germ line specification is a crucial step in the life cycle of all organisms. For sexual plant reproduction, the megaspore mother cell (MMC) is of crucial importance: it marks the first cell of the plant “germline” lineage that gets committed to undergo meiosis. One of the meiotic products, the functional megaspore, subsequently gives rise to the haploid, multicellular female gametophyte that harbours the female gametes. The MMC is formed by selection and differentiation of a single somatic, sub-epidermal cell in the ovule. The transcriptional network underlying MMC specification and differentiation is largely unknown. We provide the first transcriptome analysis of an MMC using the model plant Arabidopsis thaliana with a combination of laser-assisted microdissection and microarray hybridizations. Statistical analyses identified an over-representation of translational regulation control pathways and a significant enrichment of DEAD/DEAH-box helicases in the MMC transcriptome, paralleling important features of the animal germline. Analysis of two independent T-DNA insertion lines suggests an important role of an enriched helicase, MNEME (MEM), in MMC differentiation and the restriction of the germline fate to only one cell per ovule primordium. In heterozygous mem mutants, additional enlarged MMC-like cells, which sometimes initiate female gametophyte development, were observed at higher frequencies than in the wild type. This closely resembles the phenotype of mutants affected in the small RNA and DNA-methylation pathways important for epigenetic regulation. Importantly, the mem phenotype shows features of apospory, as female gametophytes initiate from two non-sister cells in these mutants. Moreover, in mem gametophytic nuclei, both higher order chromatin structure and the distribution of LIKE HETEROCHROMATIN PROTEIN1 were affected, indicating epigenetic perturbations. In summary, the MMC transcriptome sets the stage for future functional characterization as illustrated by the identification of MEM, a novel gene involved in the restriction of germline fate
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