400 research outputs found
A Formal Object Model for Layered Networks to Support Verification and Simulation
This work presents an abstract formal model of the interconnection structure of the Open Systems Interconnection Reference Model (OSI-RM) developed using Object-Oriented modeling principles permitting it to serve as a re-usable platform in supporting the development of simulations and formal methods applied to layered network protocols. A simulation of the object model using MODSIM III was developed and Prototype Verification System (PVS) was used to show the applicability of the object model to formal methods by formally specifying and verifying a Global Systems for Mobile communications (GSM) protocol. This application has proved to be successful in two aspects. The first was showing the existence of discrepancies between informal standard protocol specifications, and the second was that communication over the layered GSM network was verified. Although formal methods is somewhat difficult and time consuming, this research shows the need for the formal specification of all communication protocols to support a clear understanding of these protocols and to provide consistency in their implementations.
A domain for the application of this model is mobile cellular telecommunications systems. Mobile Communications is one of the most rapidly expanding sectors of telecommunications. Expectations of what a mobile cellular phone can do have vastly increased the complexity of cellular communication networks, which makes it imperative that protocol specifications be verified before implementation
An attempt to identify the extended synchrotron structure associated with the micro-quasar GRS 1915+105
The energy ejected from the galaxy micro-quasar GRS1915+105 in the form of
jets is expected to lead to formation of an extended double lobe/hot-spot
structure with the energy content comparable to an average supernova remnant.
We used the Effelsberg 100m telescope at 10.45 GHz in attempt to identify such
structures. For this distant galactic plane source any definite identification
was not possible due to high confusion by numerous background sources, however,
a few suspect structures were pointed out.Comment: LaTeX uses a new 2001 A&A macro, 4 pages, 2 figures, A&A accepte
Reconstruction of a latest Paleocene shallow-marine eutrophic paleoenvironment at Sidi Nasseur (Central Tunisia) based on foraminifera, ostracoda, calcareous nannofossils and stable isotopes (d13C, d18O)
In order to unravel faunal and paleoenvironmental parameters in shallow marine settings prior to the Paleocene- Eocene thermal maximum, we investigated the Sidi Nasseur section (NAS) in Central Tunisia. This section exposes Paleocene to lower Eocene shales and marls of the El Haria Formation. The uppermost Paleocene part of the Sidi Nasseur section is marked by poor to moderately rich, but fairly diversified nannofossil associations, containing the typical latest Paleocene taxa of the top of NP9a. The ostracode record displays an almost continuous record in the uppermost Paleocene part of the section. Representatives of Aegyptiana, Paracosta, Reticulina and Reymenticosta make up the major part of the ostracode fauna. The benthic foraminiferal assemblage consists of numerous small calcareous benthic foraminifera, like Anomalinoides midwayensis and Lenticulina spp. and many large Frondicularia phosphatica, Pyramidulina spp. These, together with the non-calcareous agglutinated foraminifera and the rare planktic foraminifera, indicate an inner neritic to coastal environment with eutrophic conditions, regularly interrupted by oxygen deficiency. The dominance of non-calcareous benthic foraminifera between intervals with abundant calcareous benthic foraminifera suggests post-mortem dissolution. The foraminiferal d13C record (based upon Pyramidulina latejugata) of the latest Paleocene in the Sidi Nasseur area is very similar to these from coeval sediments at Gebel Duwi and Gebel Aweina in Egypt. Oxygen isotopic ratios indicate a marine setting with a water composition affected by evaporation. During the latest Paleocene, the highly productive shallow water environment evolved to shallower water depths with higher salinity and increasing dominance of A. midwayensis
The potential gonadoprotective effects of grape seed extract against the histopathological alterations elicited in an animal model of cadmium-induced testicular toxicity
Background: Grape seed extract (GSE) is a powerful antioxidant containing high levels of bioflavonoids, vitamin C and vitamin E. The aim of the work is to study the possible protective and ameliorative effects of grape seed extract in an animal model of cadmium (Cd)-induced testicular toxicity in rats.Materials and methods: A thirty-day oral gavage study in adult male albino rats was performed using 32 animals, randomly divided into four equal groups; negative control, Cd (5 mg/k/day), GSE (100 mg/k/day), and Cd + GSE. Testicular weights were measured. Haematoxylin and eosin (H&E) staining and proliferating nuclear cell antigen (PCNA) immunohistochemistry, as a marker for proliferation were done. Morphometric parameters were assessed and subjected to statistical analysis.Results: The H&E results showed atrophy and distortion of the seminiferous tubules (STs) with sloughing of the spermatogenic epithelium in cadmium group. The interstitial spaces were widened and showed oedema and mononuclear cell infiltrations. No remarkable changes were observed in the GSE-only group when compared to the control group. In Cd + GSE group, maintaining of the STs and their lining cells was evident. The immunohistochemical results showed marked positive PCNA immunoreactivity in both control and GSE groups, while negative immunoreaction was noticed in Cd group. Limited positive PCNA immunoreactivity was ameliorated in Cd + GSE group.Conclusions: Grape seed extract protected against cadmium-induced testicular toxicity in rats, reducing induced histopathological changes, and maintaining testicular histoarchitecture
Assessment and Comparison of Aviation Manufacturing Industries throughout Mexico and Brazil
This literature review serves to provide insight and understanding in regards to the evolving aviation manufacturing industry throughout the globe and more specifically, Mexico and Brazil. Increased demand for aircraft units both in the commercial and private sectors have led to unprecedented expansions in aircraft manufacturing across the industry. In order to illuminate certain potentials and current growth levels of such industries, this review will delve into an array of information and specifications in regards to economic, political, and cultural influences throughout both Mexican and Brazilian markets respectively. In conclusion, the review will identify the transformation of an aviation manufacturing stronghold from one nation to another
Control of root rot and wilt disease complex of some evergreen fruit transplants by using plant growth promoting rhizobacteria in the New Valley Governorate, Egypt
Root rot and wilt disease complex were detected in several guava, lemon and olive transplant nurseries and new orchards at El-Kharga, Baris, ballet, El-Dakhla and El-Farafrah districts, the New Valley Governorate, Egypt. The average percentage of root rot/wilt incidence and severity in surveying districts were 37.7, 26.5%in guava; 41.7, 34.0%;in lemon and 41.2, 29.5% in olive transplants, respectively. The most frequently isolated fungi from rotted roots of the guava, lemon and olive transplants were Fusarium oxysporum, F. solani, Macrophomina phaseolina and Rhizoctonia solani. In pathogenicity tests, all the tested fungi were pathogenic to guava, lemon and olive transplants. The effect of plant growth promoting rhizobacteria (PGPR) individually and/or mixed when used as a soil drench treatment were varied in reducing root rot/ wilt incidence and severity under greenhouse conditions compared with control. The mixed of PGPR gave the highest protection against root rot/wilt diseases compared with the use of PGPR individually. All treatments significantly increased plant height (cm), number of leaves transplanting-1, leaf area (cm2), fresh and dry weights transplanting-1 (gm) compared with control treatment
Propositional calculus for adjointness lattices
Recently, Morsi has developed a complete syntax for the class of all
adjointness algebras . There, is a partially ordered set with top element , is a
conjunction on for which is a left identity
element, and the two implication-like binary operations and on
are adjoints of .
In this paper, we extend that formal system to one for the class of
all 9-tuples , called \emph{%
adjointness lattices}; in each of which is a bounded lattice, and is an
adjointness algebra. We call it \emph{Propositional Calculus for Adjointness
Lattices}, abbreviated . Our axiom scheme for features four
inference rules and thirteen axioms. We deduce enough theorems and
inferences in to establish its completeness for ; by means of
a quotient-algebra structure (a Lindenbaum type of algebra). We study two
negation-like unary operations in an adjointness lattice, defined by means
of together with and . We end by developing complete syntax for
all adjointness lattices whose implications are -type implications
Management of root rot and wilt diseases of date palm offshoots using certain biological control agents and its effect on growth parameters in the New Valley Governorate, Egypt
Root Rot and wilt diseases were observed on different date palm offshoots in nurseries and new orchards in New Valley Governorate, Egypt. Pathogenicity tests showed that Fusarium oxysporum, F. solani and F. moniliforme were the causal agents of root rot and wilt diseases on date palm offshoots (cv. Saidy). In addition, the isolates of the three Fusarium spp. differed in their pathogenic capabilities. The effect of Bacillus subtilis (BSM1), B. megaterium (BMM5), B. cereus (BCM8), Trichoderma viride (TVM2), T. harzianum (THM4) as bioagents against root rot/wilt disease complex of date palm offshoots under natural infection in nursery cultivated in two location (Al-Kharga and El-Dakhla) and also, on growth of the tested pathogenic fungi under laboratory were evaluated. Under laboratory conditions, all the tested bioagents inhibited the growth of the pathogenic fungi with different percentages. Bacillus megaterium and B. subtilis showed the highest percentage of fungal growth inhibition, while T. harzianum gave the lowest ones. At the field level, the application of bioagents significantly reduced the disease severity compared with untreated offshoots (control) in both locations. Bacillus megaterium and T. viride showed the highest protection against fungal causal agents, while B. cereus and T. harzianum gave the lowest ones in this respect. Moreover, the bioagents significantly improved the growth parameters of offshoots viz. plant height, number of leaves plant-1, leaflet number leaf-1, and leaf thickness. Bacillus megaterium and T. viride recorded the highest values of all growth parameters in El-Kharga and El-Dakhla locations, while B. cereus and T. harzianum gave the lowest ones.
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