Snow is Not an Enemy, But another Road in Winter

Fracture Behavior of Long Fiber Reinforced Geopolymer Composites at Different Operating Temperatures

Materials ◽

10.3390/ma15020482 ◽

2022 ◽

Vol 15 (2) ◽

pp. 482

Author(s):

Kinga Korniejenko ◽

Beata Figiela ◽

Celina Ziejewska ◽

Joanna Marczyk ◽

Patrycja Bazan ◽

...

Keyword(s):

Fracture Behavior ◽

Bending Strength ◽

Aramid Fiber ◽

Fine Aggregate ◽

River Sand ◽

Main Research ◽

Glass Carbon ◽

Different Temperatures ◽

Almost All ◽

Geopolymer Composites

The aim of this article was to analyze the fracture behavior of geopolymer composites based on fly ash or metakaolin with fine aggregate and river sand, with three types of reinforcement: glass, carbon, and aramid fiber, at three different temperatures, approximately: 3 °C, 20 °C, and 50 °C. The temperatures were selected as a future work temperature for composites designed for additive manufacturing technology. The main research method used was bending strength tests in accordance with European standard EN 12390-5. The results showed that the addition of fibers significantly improved the bending strength of all composites. The best results at room temperature were achieved for the metakaolin-based composites and sand reinforced with 2% wt. aramid fiber—17 MPa. The results at 50 °C showed a significant decrease in the bending strength for almost all compositions, which are unexpected results, taking into account the fact that geopolymers are described as materials dedicated to working at high temperatures. The test at low temperature (ca. 3 °C) showed an increase in the bending strength for almost all compositions. The grounds of this type of behavior have not been clearly stated; however, the likely causes of this are discussed.

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Colonization of depopulated crinoids by symbionts: who comes from the bottom and who from the water column?

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315415000600 ◽

2015 ◽

Vol 95 (8) ◽

pp. 1607-1612 ◽

Cited By ~ 4

Author(s):

E.S. Mekhova ◽

P.Y. Dgebuadze ◽

V.N. Mikheev ◽

T.A. Britayev

Keyword(s):

Water Column ◽

Field Experiments ◽

Dispersal Ability ◽

Long Distance ◽

Sandy Substrate ◽

Limited Dispersal ◽

Set Up ◽

Almost All ◽

High Degree

Previous experiments with the comatulid Himerometra robustipinna (Carpenter, 1881) demonstrated intensive host-to-host migration processes for almost all symbiotic species both within host aggregations and among hosts separated by several metres. The aim of this study was to check the ability of symbionts to complete long-distance migrations, by means of two in situ experiments which depopulated the crinoid host. Two different sets of field experiments were set up: exposure of depopulated crinoids (set 1) on stony ‘islands’ isolated from native crinoid assemblages by sandy substrate, and (set 2) in cages suspended in the water column. Hosts from set 1 were exposed for 1, 2, 3 and 4 weeks to assess whether substrate has an influence on the symbionts' long-distance migrations. In set 2 cages were exposed for 10–11 days, aiming to check whether symbionts were able to disperse through the water column with currents. These experiments allow the conclusion that post-settled symbionts can actively migrate among their hosts. Symbionts are able to reach their hosts by employing two different ‘transport corridors’, by drifting or swimming in water column, and by moving on the bottom. Comparison of experimental results allows the division of symbionts into two conventional groups according to the dispersal ability of their post-settled stages: (1) species able to complete long-distance migrations, (2) species unable to migrate or having limited dispersal ability. The finding of the free-living shrimp Periclimenes diversipes Kemp, 1922 in set 2 raises the question about the factors that affect such a high degree of specialization of crinoid assemblages.

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Effect of storage temperature on Streptococcus mutans viability

Revista de Odontologia da UNESP ◽

10.1590/1807-2577.08317 ◽

2018 ◽

Vol 47 (2) ◽

pp. 74-78

Author(s):

Ana Lídia Soares COTA ◽

Ronaldo Gomes ALVIM

Keyword(s):

Streptococcus Mutans ◽

Storage Temperature ◽

Storage Conditions ◽

Descriptive Statistics ◽

Bacterial Isolates ◽

Future Studies ◽

Long Period ◽

Different Temperatures ◽

Almost All ◽

Microbiological Research

Abstract Introduction Proper storage conditions and maintenance of viable biological material plays an important role in microbiological research, allowing for the opportunity to conduct future studies. Objective To evaluate the viability of Streptococcus mutans strains that were previously grown and stored under different temperatures for approximately eight years. Material and method In this study, we evaluated 393 bacterial isolates that were stored in a freezer at -80°C (G1) and 200 isolates stored in a freezer at -20°C (G2). Aliquots of each sample were plated on blood agar and mitis-salivarius bacitracin sucrose agar-solidified medium. After incubating under microaerophilic conditions in an incubator at 37°C for 72 hours, the presence, morphology and purity of bacterial growth was observed. The data were analyzed by means of descriptive statistics. Result Microbial viability was observed in almost all samples (99.7%) in G1, whereas all isolates stored at -20°C were considered inviable. Conclusion The viability of S. mutans is influenced by the storage temperature of the samples, and the strains remain viable when stored under ideal temperature conditions (-80°C), even when stored for a long period of time.

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Growth of Online Schooling in Canada

Encyclopedia of Distance Learning, Second Edition ◽

10.4018/978-1-60566-198-8.ch150 ◽

2011 ◽

pp. 1060-1065

Author(s):

M. Haughey

Keyword(s):

Rural Areas ◽

Secondary School Students ◽

New Technology ◽

Alternative Form ◽

School Students ◽

Long Distance ◽

School Aged Children ◽

Based Instruction ◽

Almost All

In Canada, a country of vast landscapes, northern climates and relatively few people, the formal provision of education has always involved alternatives. Records going back to the late 1800s discuss pilot projects that provided education to school-aged children in remote rural areas. Correspondence education, beginning in 1919 and offered by almost all provincial authorities, depended on the post and long-distance haulage to link students and teachers (Haughey, 1990). Each new technology became a part of an educational provision that was of particular importance to secondary school students, who were unable to obtain sufficient courses at their local school to qualify for a high school diploma. More recently, the advent of computers and the Internet have transformed this alternative form of education. It has changed from one for those unable to attend classroom-based instruction to one that is being chosen by students for its adaptability and flexibility, as well as for the ongoing reasons associated with long distances to schools, unavailable courses, and family and personal circumstances. In this chapter, I review the development and present configurations of online schooling in Canada and discuss trends and issues this new form of provision has raised.

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Dams and the fish fauna of the Neotropical region: impacts and management related to diversity and fisheries

Brazilian Journal of Biology ◽

10.1590/s1519-69842008000500019 ◽

2008 ◽

Vol 68 (4 suppl) ◽

pp. 1119-1132 ◽

Cited By ~ 372

Author(s):

AA. Agostinho ◽

FM. Pelicice ◽

LC. Gomes

Keyword(s):

Fish Assemblages ◽

Fish Fauna ◽

Neotropical Region ◽

Life Cycles ◽

Fish Diversity ◽

Negative Consequences ◽

Long Distance ◽

Management Actions ◽

Composition And Structure ◽

Almost All

Reservoirs have been built in almost all of the hydrographic basins of Brazil. Their purposes include water supply for cities, irrigation and mainly, generation of electricity. There are more than 700 large dams and associated reservoirs in the large rivers of the country. These reservoirs favor local and regional economic development, but they also bring serious and irreversible alterations in the natural hydrologic regime of rivers, affecting habitat quality and the dynamics of the biota. In the impounded area, the main impact is the change from lotic to lentic water, which influences aquatic fauna, including fishes. Impacts of reservoirs present relevant spatiotemporal variations. Immediately after reservoir formation, fish species richness usually increases due to incorporation of surrounding habitats, but richness decreases as reservoirs age. However, impacts downstream of dams appear to be similar or stronger than those that occur within the reservoir. Dams promote discharge control, altering the seasonal cycles of floods. These effects are augmented when dams are constructed in cascades. Therefore, dams profoundly influence composition and structure of fish assemblages. Most affected species are the rheophilics and long distance migratory that require distinct habitats to fulfill their life cycles. Populations of migratory species may collapse or even disappear in intensely regulated stretches. Management actions taken to minimize impacts of dams in Brazil historically considered construction of fish passages, fishery control and stocking. The results of these actions are questionable and/or with clear failures. In this paper, we give emphasis to the Paraná River basin, the most affected by dams in Brazil. We describe some patterns in the alteration and decline in fish diversity in areas influenced by dams. We also discuss negative consequences in the fishery and ecosystems functioning. Finally, we argue the relevance and the success of the management actions taken and present some suggestions to improve conservation of the ichthyofauna in South American basins influenced by dams.

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Does evolution of plumage patterns and of migratory behaviour in Apodini swifts (Aves: Apodiformes) follow distributional range shifts?

10.7287/peerj.preprints.797v1 ◽

2015 ◽

Cited By ~ 1

Author(s):

Dieter Thomas Tietze ◽

Michael Wink ◽

Martin Päckert

Keyword(s):

Phylogenetic Signal ◽

Visual Signals ◽

Long Distance ◽

Old World ◽

Distributional Range ◽

Speciation Rates ◽

The One ◽

Almost All ◽

The Tropics ◽

Old World Tropics

The Apodini swifts in the Old World serve as an example for a recent radiation on an intercontinental scale on the one hand. On the other hand they provide a model for the interplay of trait and distributional range evolution with speciation, extinction and trait transition rates on a low taxonomic level (23 extant taxa). Swifts are well adapted to a life mostly in the air and to long-distance movements. Their overall colouration is dull, but lighter feather patches of chin and rump stand out as visual signals. Only few Apodini taxa breed outside the tropics; they are the only species in the study group that migrate long distances to wintering grounds in the tropics and subtropics. We reconstructed a dated molecular phylogeny including all species, numerous outgroups and fossil constraints. Several methods were used for historical biogeography and two models for the study of trait evolution. We finally correlated trait expression with geographic status. The differentiation of the Apodini took place in less than 9 Ma. Their ancestral range most likely comprised large parts of the Old-World tropics, although the majority of extant taxa breed in the Afrotropic and the closest relatives occur in the Indomalayan. The expression of all three investigated traits increased speciation rates and the traits were more likely lost than gained. Chin patches are found in almost all species, so that no association with phylogeny or range could be found. Rump patches showed a phylogenetic signal and were correlated with Indomalayan distribution. Apodini swifts performed long-distance migration whenever they expanded their range to temperate latitudes during warm periods, repeatedly in the Pleistocene.

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Transport in times of an epidemic: public transport measures in the Czech Republic and its regions

Review of Economic Perspectives ◽

10.2478/revecp-2021-0004 ◽

2021 ◽

Vol 21 (1) ◽

pp. 57-78

Author(s):

Martin Vrána ◽

Simona Surmařová ◽

Petr Hlisnikovský ◽

Jiří Dujka

Keyword(s):

Czech Republic ◽

Public Transport ◽

Human Life ◽

Transport Sector ◽

Long Distance ◽

The Czech Republic ◽

Large Cities ◽

Hygiene Measures ◽

Basic Features ◽

Almost All

Abstract In the first half of 2020, the global pandemic of the COVID-19 virus became a phenomenon affecting all spheres of human life. Measures against the spread of the virus have led to restrictions in life in public spaces and have also affected the transport sector. These impacts consisted of two types - firstly, the number of connections was reduced due to a drop in transport demand, and secondly, it was necessary to comply with hygiene measures on the part of carriers and passengers. The impacts of these measures could be monitored at all spatial levels, from global to local. This paper deals with the course of the so-called first wave of the pandemic in the Czech Republic in relation to public transport and its organization. The aim of the paper is to provide an overview of these measures in relation to general government regulations and their subsequent implementation at the national, regional (county) and local (selected large cities) level. Furthermore, the paper uses three case studies to show what changes long-distance domestic transport has undergone on selected routes. There was a significant reduction in the number of long-distance connections, some lines were not operated at all, and of course, all cross-border connections were canceled. The paper covers the period from the turn of February and March 2020, when the measures began to take effect, to the end of May 2020, when almost all the adopted measures were gradually relaxed. The paper concludes with a summary of the basic features of the organization of transport during the validity of the special measures, as well as areas where significant changes took place and whose consequences may persist after the pandemic subsides.

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Smoothness of Connection of Ruled Road Surface Form Segments

10.20948/graphicon-2021-3027-762-771 ◽

2021 ◽

Author(s):

Evgeniy Lyubchinov ◽

Konstantin Panchuk

Keyword(s):

Ruled Surface ◽

Road Surface ◽

Surface Form ◽

Map Projection ◽

Surface Formation ◽

The Road ◽

Form Design ◽

Smooth Connection ◽

Two Stages ◽

Open Question

Since the modern systems of automated road surface form design have allowed us to abandon the two stages road axis design – the map projection and the cross projection – in favor of defining the road axis as a spatial curve in the form of parametric splines, the smoothness of connection of curves and surfaces comprising the roadway remains an open question. The authors further develop the cyclographic method in road surface formation and study the problem of smoothness of connection of ruled surfaces segments generated through the cyclographic mapping of a spatial curve. The present paper considers the aspects of smooth connection of polynomial spline curve segments and the respective cyclographic projections, as well as ruled surface segments that are directed by these curves. The results of the study allow one to pre-define the desirable order of smoothness of the connected curve segments and ruled surface segments comprising the road surface forms on the stage of road axis design and subsequent road surface formation. This fact can serve as the basis for development of CAD systems for road surface forms of general and special purpose.

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Cryoconites as biogeochemical markers of anthropogenic impact in high mountain regions: analysis of polyaromatic pollutants in soil-like bodies

One Ecosystem ◽

10.3897/oneeco.7.e78028 ◽

2022 ◽

Vol 7 ◽

Author(s):

Evgeny Abakumov ◽

Ivan Kushnov ◽

Timur Nizamutdinov ◽

Rustam Tembotov

Keyword(s):

Human Health ◽

Anthropogenic Activities ◽

High Mountain ◽

Long Distance ◽

Minimum Concentration ◽

Method Of Calculation ◽

Mountain Environments ◽

Central Caucasus ◽

Anthropogenic Processes ◽

Almost All

The globalisation and omnidirectional character of anthropogenic processes has challenged scientists around the world to estimate the harmful effects of these processes on ecosystems and human health. Polycyclic aromatic hydrocarbons (PAHs) is one the most infamous group of contaminants, originated both from natural and anthropogenic processes. They could transport to high latitudes and altitudes through atmospheric long-distance transfer and further enter ecosystems of these vulnerable regions by deposition on terrestrial surfaces. An interesting object for tracking transboundary contamination processes in high mountain ecosystems is called cryoconite. Cryoconite, a dark-coloured supraglacial sediment which is abundant in polar and mountain environments, is considered as a storage of various pollutants, including PAHs. Thus, it may pose a risk for local human health and ecosystem through short-distance transfer. Studied cryoconite sediments were collected at the surface of Skhelda and Garabashi glaciers, Central Caucasus high-mountain region, as well as mudflow, moraine material and local soils at the Baksan Gorge in order to examine levels of their contamination. We analysed the content of 15 priority polyaromatic compounds from the US EPA list and used the method of calculation of PAHs isomer ratios with the purpose of identifying their source. To estimate their potential toxicity, Benzo[a]pyrene (BaP) equivalents were calculated. Maximum concentration was defined for NAP (84 ng×g-1), PHE (40 ng×g-1) and PYR (47 ng×g-1), with the minimum concentration for ANT (about 1 ng×g-1). The most polluted material is a cryoconite from Garabashi glacier because of local anthropogenic activities and long-distance transfer. High-molecular weight PAHs are dominated in PAHs composition of almost all samples. The most common sources of PAHs in studied materials are combustion processes and mixed pyrolytic/petrogenic origin. Toxicity levels of separate PAHs did not exceed the maximum permissible threshold concentrations values in most cases. However, the sum of PAHs in BaP equivalents exceed the threshold values in all samples, in some of them more than twice.

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In-vehicle noise exposure among military personnel depending on type of vehicle, riding compartment and road surface

Journal of the Royal Army Medical Corps ◽

10.1136/jramc-2018-001091 ◽

2019 ◽

pp. jramc-2018-001091 ◽

Cited By ~ 1

Author(s):

Assar Luha ◽

E Merisalu ◽

M Reinvee ◽

S Kinnas ◽

R Jõgeva ◽

...

Keyword(s):

Hearing Loss ◽

Military Personnel ◽

Military Service ◽

Noise Exposure ◽

Road Surface ◽

Noise Induced Hearing Loss ◽

Noise Levels ◽

Long Distance ◽

Vehicle Noise ◽

Paved Road

IntroductionNoise-induced hearing loss is one of the most common health problems among military service personnel. Exposure to noise in military vehicles constitutes a large proportion of total noise exposure. This pilot study aimed to evaluate in-vehicle noise levels depending on the type of vehicle, riding compartment and road surface.MethodNoise levels were measured in armoured personnel carriers and heavy all-terrain trucks, in the cab and rear passenger compartment, while driving on paved or off-road surfaces. The results were compared with national LLV and allowed noise exposure times were calculated per vehicle and surface.ResultsThe equivalent noise levels in the cab of SISU XA-188 (p=0.001) and peak noise levels in MAN 4620 (p=0.0001) and DAF 4440 (p=0.0047) were higher on paved road, compared with off-road. The equivalent noise levels in the canvas covered rear compartment of MAN 4620 were significantly higher than in the cab on both paved (p=0.004) and off-road (p=0.0003). Peak noise levels in the cab of DAF 4440 exceeded the parameters measured in the canvas covered rear compartment on both paved (p=0.002) and off-road (p=0.0002). In most cases, peak noise levels were below the LLV (p=0.02–0.0001). The maximum noise exposure to passengers in the canvas covered rear compartment of MAN 4620 despite road surface was calculated 0.6 hours per working day.ConclusionA high risk of noise-induced hearing loss among military personnel occurs during long distance transportation with vehicles showing noise levels higher than allowed LLV.

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