A Model for the Development of the Rhizobial and Arbuscular Mycorrhizal Symbioses in Legumes and Its Use to Understand the Roles of Ethylene in the Establishment of these two Symbioses

We propose a model depicting the development of nodulation and arbuscular mycorrhizae. Both processes are dissected into many steps, using Pisum sativum L. nodulation mutants as a guideline. For nodulation, we distinguish two main developmental programs, one epidermal and one cortical. Whereas Nod factors alone affect the cortical program, bacteria are required to trigger the epidermal events. We propose that the two programs of the rhizobial symbiosis evolved separately and that, over time, they came to function together. The distinction between these two programs does not exist for arbuscular mycorrhizae development despite events occurring in both root tissues. Mutations that affect both symbioses are restricted to the epidermal program. We propose here sites of action and potential roles for ethylene during the formation of the two symbioses with a specific hypothesis for nodule organogenesis. Assuming the epidermis does not make ethylene, the microsymbionts probably first encounter a regulatory level of ethylene at the epidermis–outermost cortical cell layer interface. Depending on the hormone concentrations there, infection will either progress or be blocked. In the former case, ethylene affects the cortex cytoskeleton, allowing reorganization that facilitates infection; in the latter case, ethylene acts on several enzymes that interfere with infection thread growth, causing it to abort. Throughout this review, the difficulty of generalizing the roles of ethylene is emphasized and numerous examples are given to demonstrate the diversity that exists in plants

Scintillation Counters for the D0 Muon Upgrade

We present the results of an upgrade to the D0 muon system. Scintillating counters have been added to the existing central D0 muon system to provide rejection for cosmic ray muons and out-of-time background, and to provide additional fast timing information for muons in an upgraded Tevatron. Performance and results from the 1994-1996 Tevatron run are presented.Comment: 30 pages, 25 postscript figure

Comparative Evaluation of Remineralization Agents on Early Enamel Caries Lesions: An In Vitro Study

Dental caries remains one of the most prevalent chronic conditions worldwide, with early enamel demineralization being the first detectable clinical manifestation. The progression of these incipient lesions is reversible, provided that effective remineralization strategies are employed at the earliest stage of development. Recent advances in preventive dentistry have led to the development of various remineralization agents, each with unique mechanisms of action and potential benefits. This in vitro study was designed to comparatively evaluate the efficacy of three commonly used remineralization agents: fluoride-based formulations, casein phosphopeptide–amorphous calcium phosphate (CPP-ACP), and bioactive glass in reversing early enamel caries lesions. A total of extracted sound human premolars were sectioned and subjected to controlled demineralization to simulate initial carious lesions. The samples were then randomly divided into experimental groups based on the remineralization agent applied, along with a control group maintained in artificial saliva. Over a defined treatment period, each group was exposed to its respective agent under standardized laboratory conditions. The degree of remineralization was assessed using surface microhardness testing, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) to evaluate changes in surface integrity, mineral deposition, and calcium-phosphate ratio. The findings demonstrated that all tested agents produced measurable improvements in enamel hardness and mineral recovery compared to the control group. Fluoride treatments significantly enhanced surface microhardness, confirming their long-established role in caries prevention. CPP-ACP displayed superior penetration into subsurface lesions, promoting uniform mineral deposition and stabilizing amorphous calcium phosphate within the lesion body. Bioactive glass exhibited pronounced surface remineralization, characterized by the formation of a hydroxycarbonate apatite layer that effectively sealed enamel porosities. Among the groups, CPP-ACP and bioactive glass exhibited higher potential for lesion repair beyond the superficial layer, suggesting their advantages in deeper lesion management. This comparative evaluation highlights that while fluoride remains a cornerstone in caries prevention, novel agents such as CPP-ACP and bioactive glass offer promising adjunctive or alternative solutions in managing early enamel caries lesions. Their complementary mechanisms of action, ranging from enhancing resistance to acid attack to restoring the mineral balance within enamel, underscore the importance of personalized preventive strategies. Clinically, these findings reinforce the value of integrating biomimetic and bioactive remineralization technologies into preventive protocols, potentially reducing the need for invasive restorative interventions

Rhizobacterial influence on healthy stand establishment of canola grown in Rhizoctonia solani infested fields of Saskatchewan

Non-Peer ReviewedPre-emergence seedling damping-off, seedling blight, and brown girdling root rot caused by R. solani are important diseases of canola/rape seed in western Canada. Annual yield losses in excess of 20-30% have been reported in several infected fields. Cultural control methods or resistant cultivars are currently unavailable for these diseases. Chemical fungicides have been developed for use to control the disease, but the success rate has been varied. However, the use of chemicals is becoming less acceptable from an environmental point of view. Several studies indicated that biological control using plant growth promoting rhizobacteria may also be effective in controlling R. solani. Field plots were established in Saskatoon, Regina and Melfort, SK, in 1990, 1991 and 1992 to evaluate the potential of rhizobacterial strains as seed treatments to increase the healthy stand of canola CV. Westar grown in R. solani infested field. The bacteria were formulated either in sterile peat or in a liquid carrier and applied to seed just before planting. Bacterized seed were mechanically planted in replicated field plots artificially infested with R. solani. Final healthy stand was measured 30 days after planting. Grain yields were determined by harvesting the plots. Seed bacterization significantly increased the final healthy stand compared to non-bacterized controls. Strains which increased stand showed in vitro antagonistic activity to not only R. solani but also other pathogens such as Pythium ultimum, Fusarium solani and F. oxysporum. Some of these strains induced root elongation of canola under laboratory conditions. Rhizosphere colonization, chemical compatibility and shelf-life of the important bacteria will be discussed

A Survey of Cybersecurity of Digital Manufacturing

The Industry 4.0 concept promotes a digital manufacturing (DM) paradigm that can enhance quality and productivity, which reduces inventory and the lead time for delivering custom, batch-of-one products based on achieving convergence of additive, subtractive, and hybrid manufacturing machines, automation and robotic systems, sensors, computing, and communication networks, artificial intelligence, and big data. A DM system consists of embedded electronics, sensors, actuators, control software, and interconnectivity to enable the machines and the components within them to exchange data with other machines, components therein, the plant operators, the inventory managers, and customers. This article presents the cybersecurity risks in the emerging DM context, assesses the impact on manufacturing, and identifies approaches to secure DM

Solar System Abundances of the Elements

Representative abundances of the chemical elements for use as a solar abundance standard in astronomical and planetary studies are summarized. Updated abundance tables for solar system abundances based on meteorites and photospheric measurements are presented.Comment: 46 pages; 5 figures; 8 tables; In: Principles and Perspectives in Cosmochemistry.Lecture Notes of the Kodai School on 'Synthesis of Elements in Stars' held at Kodaikanal Observatory, India, April 29 - May 13, 2008 (Aruna Goswami and B. Eswar Reddy eds.) Astrophysics and Space Science Proceedings, Springer-Verlag Berlin Heidelberg, 2010, p. 379-417 (ISBN 978-3-642-10351-3), 201