scholarly journals Lepidium oblongum (Brassicaceae) appeared on Hungarian railways

2022 ◽  
Vol 81 (1) ◽  
Author(s):  
Dávid Schmidt ◽  
Attila Mesterházy ◽  
János Csiky
Keyword(s):  
High Stress ◽  
Morphological Characteristics ◽  
Climatic Parameters ◽  
Spread Rate ◽  
Railway Tracks ◽  
Adventive Flora ◽  
Railway Workers ◽  
Continental Climate

Lepidium oblongum, of American origin is a new member of the European adventive flora, only detected in Romania so far. The first Hungarian stand was discovered in 2018, and others in 2020. Based on our studies, we detail its morphological characteristics in comparison with other Lepidium species. We present a new drawing and a table to help identify the species. Lepidium oblongum is easily identifiable by its divided (lobed or lobed-dentated) upper stem leaves. By analyzing selected climatic parameters we show that the new European habitats are found in the drier and cooler summer subtype of the humid continental climate belt. In Hungary, it spreads directly along the railways. The establishment of individual populations can be influenced by the location of cargo unloading and the movement of railway workers. Lepidium oblongum occupies gravelly, sun-exposed habitats along Hungarian railway tracks such as loading platforms, guardhouses and goods stations. Based on its high stress and climatic tolerance and initial spread-rate, it is consider to be a naturalized member of the European adventive flora, that could be potentially invasive along the European railways

Modeling the mechanical behavior of railway ballast using artificial neural networks

2006 ◽  
Vol 43 (11) ◽  
pp. 1144-1152 ◽  
Author(s):  
Mohamed A Shahin ◽  
Buddhima Indraratna
Keyword(s):  
Neural Networks ◽  
Artificial Neural Networks ◽  
Mechanical Behavior ◽  
Triaxial Compression ◽  
High Stress ◽  
Triaxial Tests ◽  
Ann Model ◽  
Railway Ballast ◽  
Railway Tracks ◽  
Artificial Neural

Ballast is one of the most commonly used construction materials in railway tracks. Under heavy train loads, ballast is subjected to a high stress level that is always associated with significant track deformation. Consequently, an accurate prediction of the mechanical behavior of ballast under static and dynamic loading conditions is important for the stability of railway tracks. In this paper, the feasibility of using artificial neural networks (ANNs) for modeling the mechanical behavior of railway ballast under static loading is investigated. The database used for the development of the ANN model is obtained from selected literature and comprises a series of 29 large-scale drained triaxial compression tests conducted on three types of commonly used ballast (i.e., basalt, dolomite, and granite). Predictions from the ANN model are compared with the results of experimental tests and with those obtained from the hardening-soil constitutive model in PLAXIS finite-element code. The results indicate that the ANN model is able to accurately predict the stress–strain and volume change behavior of ballast. The plastic dilation and contraction of ballast at various confining pressures and the strain-hardening and postpeak strain-softening behavior of ballast are also well simulated.Key words: ballast, modeling, neural networks, prediction, railway, triaxial tests.

Cell Wall Ultrastructure in Three Strains of a Cariogenic Streptococcus

1971 ◽  
Vol 29 ◽  
pp. 338-339
Author(s):  
M. J. Kramer ◽  
Alan L. Coykendall
Keyword(s):  
Cell Wall ◽  
Dental Caries ◽  
Streptococcus Mutans ◽  
Microscopic Study ◽  
Electron Microscopic Study ◽  
Genetic Heterogeneity ◽  
Morphological Characteristics ◽  
Electron Microscopic ◽  
Dna Reassociation ◽  
Wall Ultrastructure

During the almost 50 years since Streptococcus mutans was first suggested as a factor in the etiology of dental caries, a multitude of studies have confirmed the cariogenic potential of this organism. Streptococci have been isolated from human and animal caries on numerous occasions and, with few exceptions, they are not typable by the Lancefield technique but are relatively homogeneous in their biochemical reactions. An analysis of the guanine-cytosine (G-C) composition of the DNA from strains K-1-R, NCTC 10449, and FA-1 by one of us (ALC) revealed significant differences and DNA-DNA reassociation experiments indicated that genetic heterogeneity existed among the three strains. The present electron microscopic study had as its objective the elucidation of any distinguishing morphological characteristics which might further characterize the respective strains.

Aberrant Type C Virus Production in a Cell Line Derived from Balb/3T3

1972 ◽  
Vol 30 ◽  
pp. 286-287
Author(s):  
N. Savage ◽  
A. Hackett
Keyword(s):  
Electron Microscopy ◽  
Cell Line ◽  
Leukemia Virus ◽  
Morphological Characteristics ◽  
Virus Production ◽  
Oncogenic Viruses ◽  
Endogenous Virus ◽  
Virus Particles ◽  
Moloney Leukemia Virus ◽  
A Cell

A cell line, UC1-B, which was derived from Balb/3T3 cells, maintains the same morphological characteristics of the non-transformed parental culture, and shows no evidence of spontaneous virus production. Survey by electron microscopy shows that the cell line consists of spindle-shaped cells with no unusual features and no endogenous virus particles.UC1-B cells respond to Moloney leukemia virus (MLV) infection by a change in morphology and growth pattern which is typical of cells transformed by sarcoma virus. Electron microscopy shows that the cells are now variable in shape (rounded, rhomboid, and spindle), and each cell type has some microvilli. Virtually all (90%) of the cells show virus particles developing at the cell surface and within the cytoplasm. Maturing viruses, typical of the oncogenic viruses, are found along with atypical tubular forms in the same cell.

SEM/FESEM imaging of lamellar structures in melt extruded polyethylene films

1992 ◽  
Vol 50 (2) ◽  
pp. 1142-1143
Author(s):  
R.T. Chen ◽  
M.G. Jamieson ◽  
R. Callahan
Keyword(s):  
Imaging Techniques ◽  
Membrane Surface ◽  
High Stress ◽  
Extrusion Direction ◽  
Polymeric Membranes ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Crystalline Polymers ◽  
Lamellar Structures ◽  
Resolution Imaging

“Row lamellar” structures have previously been observed when highly crystalline polymers are melt-extruded and recrystallized under high stress. With annealing to perfect the stacked lamellar superstructure and subsequent stretching in the machine (extrusion) direction, slit-like micropores form between the stacked lamellae. This process has been adopted to produce polymeric membranes on a commercial scale with controlled microporous structures. In order to produce the desired pore morphology, row lamellar structures must be established in the membrane precursors, i.e., as-extruded and annealed polymer films or hollow fibers. Due to the lack of pronounced surface topography, the lamellar structures have typically been investigated by replica-TEM, an indirect and time consuming procedure. Recently, with the availability of high resolution imaging techniques such as scanning tunneling microscopy (STM) and field emission scanning electron microscopy (FESEM), the microporous structures on the membrane surface as well as lamellar structures in the precursors can be directly examined.The materials investigated are Celgard® polyethylene (PE) flat sheet membranes and their film precursors, both as-extruded and annealed, made at different extrusion rates (E.R.).

Crystallization sequence of an A1N-Y2O3-SiO2 glass-ceramic

1986 ◽  
Vol 44 ◽  
pp. 446-447
Author(s):  
T.R. Dinger ◽  
G. Thomas
Keyword(s):  
High Temperature ◽  
Glass Ceramic ◽  
Crystallization Behavior ◽  
High Stress ◽  
Crystallization Sequence ◽  
Sio2 Glass ◽  
Structural Applications ◽  
Ceramic Precursors

The use of Si3N4, alloys for high temperature, high stress structural applications has prompted numerous studies of the oxynitride glasses which exist as intergranular phases in their microstructures. Oxynitride glasses have been investigated recently in their bulk form in order to understand their crystallization behavior for subsequent Si3N4 applications and to investigate their worth as glass-ceramic precursors. This research investigates the crystallization sequence of a glass having a normalized composition of Y26Si30Al11 ON11 and lying in the A1N-Y2O3-SiO2 section of the Y-Si-Al-O-N system. Such glasses exist as intergranular phases in the technologically important Y2O3/Al2O3-fluxed Si3N4 alloys.

DNA nick end labeling: a reliable marker for apoptosis?

1995 ◽  
Vol 53 ◽  
pp. 962-963
Author(s):  
Anne F. Bushnell ◽  
Sarah Webster ◽  
Lynn S. Perlmutter
Keyword(s):  
Cell Death ◽  
Cultured Cells ◽  
Apoptotic Cell ◽  
Morphological Characteristics ◽  
Detection Methods ◽  
Tissue Preparation ◽  
Preparation Methods ◽  
Dna Laddering ◽  
Disease States ◽  
Reliable Marker

Apoptosis, or programmed cell death, is an important mechanism in development and in diverse disease states. The morphological characteristics of apoptosis were first identified using the electron microscope. Since then, DNA laddering on agarose gels was found to correlate well with apoptotic cell death in cultured cells of dissimilar origins. Recently numerous DNA nick end labeling methods have been developed in an attempt to visualize, at the light microscopic level, the apoptotic cells responsible for DNA laddering.The present studies were designed to compare various tissue processing techniques and staining methods to assess the occurrence of apoptosis in post mortem tissue from Alzheimer's diseased (AD) and control human brains by DNA nick end labeling methods. Three tissue preparation methods and two commercial DNA nick end labeling kits were evaluated: the Apoptag kit from Oncor and the Biotin-21 dUTP 3' end labeling kit from Clontech. The detection methods of the two kits differed in that the Oncor kit used digoxigenin dUTP and anti-digoxigenin-peroxidase and the Clontech used biotinylated dUTP and avidinperoxidase. Both used 3-3' diaminobenzidine (DAB) for final color development.

SEM and TEM observations of sperm development in the testis of the freshwater fish Oreochromis mossambicus

1990 ◽  
Vol 48 (3) ◽  
pp. 58-59
Author(s):  
Daryl A. Cornish ◽  
George L. Smit
Keyword(s):  
Morphological Characteristics ◽  
Oreochromis Mossambicus ◽  
Breeding Cycle ◽  
Limited Information ◽  
North West ◽  
The North ◽  
Sem And Tem ◽  
Sperm Development ◽  
Ultrastructural Characteristics ◽  
The University

Oreochromis mossambicus is currently receiving much attention as a candidater species for aquaculture programs within Southern Africa. This has stimulated interest in its breeding cycle as well as the morphological characteristics of the gonads. Limited information is available on SEM and TEM observations of the male gonads. It is known that the testis of O. mossambicus is a paired, intra-abdominal structure of the lobular type, although further details of its characteristics are not known. Current investigations have shown that spermatids reach full maturity some two months after the female becomes gravid. Throughout the year, the testes contain spermatids at various stages of development although spermiogenesis appears to be maximal during November when spawning occurs. This paper describes the morphological and ultrastructural characteristics of the testes and spermatids.Specimens of this fish were collected at Syferkuil Dam, 8 km north- west of the University of the North over a twelve month period, sacrificed and the testes excised.

Approaches for TEM imaging of cavitation in toughened nylon

1989 ◽  
Vol 47 ◽  
pp. 352-353
Author(s):  
Barbara A. Wood
Keyword(s):  
Morphological Characteristics ◽  
Structure Property ◽  
Polymer Systems ◽  
Selective Staining ◽  
Structure Property Relationships ◽  
Rubber Toughened ◽  
Shear Yield ◽  
Controversial Topic ◽  
Selection Of ◽  
Diamond Knife

A controversial topic in the study of structure-property relationships of toughened polymer systems is the internal cavitation of toughener particles resulting from damage on impact or tensile deformation.Detailed observations of the influence of morphological characteristics such as particle size distribution on deformation mechanisms such as shear yield and cavitation could provide valuable guidance for selection of processing conditions, but TEM observation of damaged zones presents some experimental difficulties.Previously published TEM images of impact fractured toughened nylon show holes but contrast between matrix and toughener is lacking; other systems investigated have clearly shown cavitated impact modifier particles. In rubber toughened nylon, the physical characteristics of cavitated material differ from undamaged material to the extent that sectioning of heavily damaged regions by cryoultramicrotomy with a diamond knife results in sections of greater than optimum thickness (Figure 1). The detailed morphology is obscured despite selective staining of the rubber phase using the ruthenium trichloride route to ruthenium tetroxide.

Iterative Development of a Home Review Program to Promote Preschoolers' Vocabulary Skills: Social Validity and Learning Outcomes

2020 ◽  
Vol 51 (2) ◽  
pp. 371-389 ◽  
Author(s):  
Xigrid Soto ◽  
Yagmur Seven ◽  
Meaghan McKenna ◽  
Keri Madsen ◽  
Lindsey Peters-Sanders ◽  
...  
Keyword(s):  
High Stress ◽  
Social Validity ◽  
Home Language ◽  
Single Subject ◽  
Considerable Difficulty ◽  
Home Program ◽  
Iterative Development ◽  
Vocabulary Skills ◽  
Validity Measures ◽  
At Home

Purpose This article describes the iterative development of a home review program designed to augment vocabulary instruction for young children (ages 4 and 5 years) occurring at school through the use of a home review component. Method A pilot study followed by two experiments used adapted alternating treatment designs to compare the learning of academic words taught at school to words taught at school and reviewed at home. At school, children in small groups were taught academic words embedded in prerecorded storybooks for 6 weeks. Children were given materials such as stickers with review prompts (e.g., “Tell me what brave means”) to take home for half the words. Across iterations of the home intervention, the home review component was enhanced by promoting parent engagement and buy-in through in-person training, video modeling, and daily text message reminders. Visual analyses of single-subject graphs, multilevel modeling, and social validity measures were used to evaluate the additive effects and feasibility of the home review component. Results Social validity results informed each iteration of the home program. The effects of the home program across sites were mixed, with only one site showing consistently strong effects. Superior learning was evident in the school + home review condition for families that reviewed words frequently at home. Although the home review program was effective in improving the vocabulary skills of many children, some families had considerable difficulty practicing vocabulary words. Conclusion These studies highlight the importance of using social validity measures to inform iterative development of home interventions that promote feasible strategies for enhancing the home language environment. Further research is needed to identify strategies that stimulate facilitators and overcome barriers to implementation, especially in high-stress homes, to enrich the home language environments of more families.

Critical Review on Suicide Among Nurses

Crisis ◽  
2015 ◽  
Vol 36 (2) ◽  
pp. 91-101 ◽  
Author(s):  
Marie Alderson ◽  
Xavier Parent-Rocheleau ◽  
Brian Mishara
Keyword(s):  
Risk Factors ◽  
Literature Review ◽  
High Stress ◽  
Related Factors ◽  
Work Settings ◽  
Work Related ◽  
High Prevalence ◽  
Full Text Review ◽  
The Subject ◽  
Psychiatric Problems

Background: Research shows that there is a high prevalence of suicide among nurses. Despite this, it has been 15 years since the last literature review on the subject was published. Aim: The aim of this article is to review the knowledge currently available on the risk of suicide among nurses and on contributory risk factors. Method: A search was conducted in electronic databases using keywords related to prevalence and risk factors of suicide among nurses. The abstracts were analyzed by reviewers according to selection criteria. Selected articles were submitted to a full-text review and their key elements were summarized. Results: Only nine articles were eligible for inclusion in this review. The results of this literature review highlight both the troubling high prevalence of suicide among nurses as well as the persistent lack of studies that examine this issue. Conclusion: Considering that the effects of several factors related to nurses' work and work settings are associated with high stress, distress, or psychiatric problems, we highlight the relevance of investigating work-related factors associated with nurses' risk of suicide. Several avenues for future studies are discussed as well as possible research methods.

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