Journal articles: 'Undisturbed environment'

1

McDowell, J. J., and Marcia L. Caron. "MATCHING IN AN UNDISTURBED NATURAL HUMAN ENVIRONMENT." Journal of the Experimental Analysis of Behavior 93, no. 3 (May 2010): 415–33. http://dx.doi.org/10.1901/jeab.2010.93-415.

Full text

APA, Harvard, Vancouver, ISO, and other styles

2

Nuijens, Louise, Bjorn Stevens, and A. Pier Siebesma. "The Environment of Precipitating Shallow Cumulus Convection." Journal of the Atmospheric Sciences 66, no. 7 (July 1, 2009): 1962–79. http://dx.doi.org/10.1175/2008jas2841.1.

Full text

Abstract:

Abstract Quantitative estimates of precipitation in a typical undisturbed trade wind region are derived from 2 months of radar reflectivity data and compared to the meteorological environment determined from soundings, surface flux, and airborne-lidar data. Shallow precipitation was ubiquitous, covering on average about 2% of the region and contributing to at least half of the total precipitation. Echo fractions on the scale of the radar domain range between 0% and 10% and vary greatly within a period from a few hours to a day. Variability in precipitation relates most strongly to variability in humidity and the zonal wind speed, although greater inversion heights and deeper clouds are also evident at times of more rain. The analysis herein suggests that subtle fluctuations in both the strength of the easterlies and in subsidence play a major role in regulating humidity and hence precipitation, even within a given meteorological regime (here, the undisturbed trades).

APA, Harvard, Vancouver, ISO, and other styles

3

Briard, L., C. Goujarde, C. Bousquet, and A. Dussutour. "Stress signalling in acellular slime moulds and its detection by conspecifics." Philosophical Transactions of the Royal Society B: Biological Sciences 375, no. 1802 (May 18, 2020): 20190470. http://dx.doi.org/10.1098/rstb.2019.0470.

Full text

Abstract:

Unicellular organisms live in unpredictable environments. Therefore, they need to continuously assess environmental conditions and respond appropriately to survive and thrive. When subjected to rapid changes in their environment or to cellular damages, unicellular organisms such as bacteria exhibit strong physiological reactions called stress responses that can be sensed by conspecifics. The ability to detect and use stress-related cues released by conspecifics to acquire information about the environment constitutes an adaptive survival response by prompting the organism to avoid potential dangers. Here, we investigate stress signalling and its detection by conspecifics in a unicellular organism, Physarum polycephalum . Slime moulds were subjected to either biotic (i.e. nutritional) or abiotic (i.e. chemical and light) stressors or left undisturbed while they were exploring a homogeneous environment. Then, we observed the responses of slime moulds facing a choice between cues released by stressed clone mates and cues released by undisturbed ones. We found that slime moulds actively avoided environments previously explored by stressed clone mates. These results suggest that slime moulds, like bacteria or social amoeba, exhibit physiological responses to biotic and abiotic stresses that can be sensed by conspecifics. Our results establish slime moulds as a promising new model to investigate the use of social information in unicellular organisms. This article is part of the theme issue ‘Signal detection theory in recognition systems: from evolving models to experimental tests’.

APA, Harvard, Vancouver, ISO, and other styles

4

Yellajosula, Gayatri, Larry Cihacek, Tim Faller, and Christopher Schauer. "Soil Carbon Change Due to Land Conversion to Grassland in a Semi-Arid Environment." Soil Systems 4, no. 3 (July 16, 2020): 43. http://dx.doi.org/10.3390/soilsystems4030043.

Full text

Abstract:

A 5-year study evaluated the change in the quantity of soil total C (STC), soil organic C (SOC), and soil inorganic C (SIC) stored in the surface 60 cm of the soil profile on two adjacent blocks of land with a long-term history of cropping (CH) or undisturbed grassland (NH) on similar soil types between 1999 and 2004. The NH area was tilled and a grass-legume species mix was seeded into plots on both the NH and the CH areas. Selected plots of restored grass were established so they could be grazed (GG) by livestock while other plots were left ungrazed (UG). Original undisturbed (and ungrazed) grassland plots within the NH area were used as a control treatment. Initially, STC and SOC in CH were lower than NH when compared under the semi-arid environmental conditions found in southwestern North Dakota. Over the study period, the undisturbed grass control plots had increases in STC and SOC levels in the soil profile of 3.90 kg·m−2 and 3.34 kg·m−2, respectively. Restored grass on the NH area with grazing showed increases in STC and SOC values of 2.11 and 1.26 kg·m−2, respectively, while without grazing, profile STC and SOC had values of 3.80 and 3.28 kg·m−2, respectively. Restored grass on the CH area showed increases in profile STC and SOC values of 0.55 and 1.96 kg·m−2, respectively, for the grazed plots and 0.78 and 2.11 kg·m−2, respectively, when left ungrazed. Soil inorganic C, though present in the soils, did not significantly change during the study. The lower C accumulation in the CH plots may be due to a lag time in the establishment of mycorrhizal associations with the seeded species, the inoculums of which were already present in the NH soils. Changes in STC were likely due to changes in water relationships in the soil profile where management changes affected water infiltration and its movement causing leaching of SIC below the 60 cm depth evaluated. Soils under undisturbed grassland continue to accumulate carbon while soils of the disturbed grassland or cropped prior to re-establishing grass showed losses that occurred due to either accumulating C at a lower rate or perhaps to C loss during the initial establishment period (1–2 years).

APA, Harvard, Vancouver, ISO, and other styles

5

Dias, Alesandra Martins, and Francisco Leonardo Tejerina-Garro. "Changes in the structure of fish assemblages in streams along an undisturbed-impacted gradient, upper Paraná River basin, Central Brazil." Neotropical Ichthyology 8, no. 3 (2010): 587–98. http://dx.doi.org/10.1590/s1679-62252010000300003.

Full text

Abstract:

The João Leite River is located in the upper Paraná basin, Central Brazil. It drains areas covered by Cerrado vegetation interspersed with urban and agricultural areas. This study aims to asses changes of the fish assembleges structure along a undisturbed-impacted gradient in ten stream stretches using ecological descriptors, a similarity index and the abundance-biomass relationship (ABC curves). The fish were collected during the dry period using electrofishing gear in stretches of 50 m. Results show that the environmental variation observed along the undisturbed-impacted gradient considered influences on fish assemblage structure. Both richness and diversity differences between fish assemblages are partially influenced by stream stretch orthonian order and anthropogenic impacts. ABC curves classified six stream stretches located in preserved or impacted areas as undisturbed while four stretches were classified as disturbed. This is attributed to the influence of the undisturbed habitat within the conservation unit and the presence of K- or r- strategist species. This type of study contributes to an understanding of the effects of aquatic environment conservation on the Brazilian Cerrado core area, where the choice of conservation areas prioritizes terrestrial over aquatic aspects.

APA, Harvard, Vancouver, ISO, and other styles

6

Malash, Kateryna Mykolaiivna, and Andrii Bomba. "Modelling of an explosion impact on a deformable medium with rigid inclusions with quasiconformal mappings methods." Modeling, Control and Information Technologies, no. 4 (October 22, 2020): 19–22. http://dx.doi.org/10.31713/mcit.2020.04.

Full text

Abstract:

The explosive process influence on the environment with the existing impenetrable fixed inclusion is investigated by quasiconformal mappings numerical methods and step-by-step parameterization of the environment and the process characteristics numerical methods. The boundaries of the crater formed by the explosion, pressed and undisturbed areas of soil are determined. Numerical experiments were performed on the basis of the developed algorithm

APA, Harvard, Vancouver, ISO, and other styles

7

Álvarez, Alberto, W. Owen McMillan, Néstor Pérez-Buitrago, Alberto Sabat, and Miguel García. "Spatial ecology of the Mona Island iguana Cyclura cornuta stejnegeri in an undisturbed environment." Applied Herpetology 4, no. 4 (2007): 347–55. http://dx.doi.org/10.1163/157075407782424575.

Full text

APA, Harvard, Vancouver, ISO, and other styles

8

Kullberg, Russell G. "Decreased diversity caused by differential inhibition among artificial phytoplankton communities in an undisturbed environment." European Journal of Phycology 30, no. 4 (November 1995): 267–72. http://dx.doi.org/10.1080/09670269500651041.

Full text

APA, Harvard, Vancouver, ISO, and other styles

9

Scheltema, MA, LK Abbott, and AD Robson. "Seasonal variation in the infectivity of VA mycorrhizal fungi in annual pastures in a Mediterranean environment." Australian Journal of Agricultural Research 38, no. 4 (1987): 707. http://dx.doi.org/10.1071/ar9870707.

Full text

Abstract:

The seasonal variation in the rate and extent of formation of mycorrhizas in pasture soils from two sites in south-west Australia was examined. Undisturbed soil cores were taken on eight occasions throughout the year, sown with Trifolium subterraneum L. and maintained in a glasshouse. At each collection time the extent of formation of mycorrhizas was measured 3 and 6 weeks after sowing.There was no seasonal variation in the extent of mycorrhizas formed in undisturbed soil cores at one site, hut at the other site the extent of mycorrhizas decreased over time. The rate of formation of mycorrhizas was most rapid when cores were collected immediately after the opening rains of the season.Similar species of fungi were present at both sites; however, the rate and extent of infection formed by each species differed between the sites. At both sites the infectivity of A. laevis and fine endophyte decreased throughout the winter months, but the infectivity of Glomus spp. did not change. Neither the total spore number nor an estimate of the number of infective propagules reflected the infectivity of the total population of VA mycorrhizal fungi measured simultaneously at the two sites.

APA, Harvard, Vancouver, ISO, and other styles

10

Sazanova, K. V. "STATISTICAL MODELS OF THE METABOLOME OF LITHOBIONTIC COMMUNITIES IN NATURAL AND URBANIZED CONDITIONS." Ecology. Economy. Informatics.System analysis and mathematical modeling of ecological and economic systems 1, no. 6 (2021): 155–60. http://dx.doi.org/10.23885/2500-395x-2021-1-6-155-160.

Full text

Abstract:

The composition of metabolites in various types of biolayering on the marble surface in natural outcrops and in an urban environment has been studied. Metabolomic profiling was performed by gas chromatographymass spectrometry. It was found that biolayering in the urban environment is much less diverse biochemically than in anthropogenically undisturbed conditions. The differences in metabolomic data were significantly greater between sampling sites than between community types. Lithobiontic communities of organisms are an interesting and promising for bioindication and biomonitoring of the environment.

APA, Harvard, Vancouver, ISO, and other styles

11

Larsson, Gerry, and Aida Alvinius. "“An undisturbed afternoon of writing”: a qualitative study of professors’ job satisfaction." Journal of Applied Research in Higher Education 11, no. 4 (October 14, 2019): 719–32. http://dx.doi.org/10.1108/jarhe-10-2018-0216.

Full text

Abstract:

Purpose The purpose of this paper is to model factors that contribute to job satisfaction among university professors. Design/methodology/approach The approach was qualitative; 12 in-depth interviews were conducted with Swedish university full professors representing 11 different academic subjects. Findings Five facets of job satisfaction were identified: distal environment (e.g. impact on society and the scientific community), proximal social environment, self (e.g. receiving external credit and experiencing internal pride), the uplifts of daily life and formal conditions (e.g. pay and opportunities to continue after retirement). A model was inductively developed according to which professors’ job satisfaction is influenced by interacting contextual and individual antecedent conditions. Research limitations/implications Because a qualitative approach was used, with a limited number of informants, there is a lack of representativeness and the concepts generated are of a sensitizing rather than a definitive character. Practical implications Attention should be paid to university professors’ need for autonomy, otherwise public management control strivings may become counter-productive. Originality/value A new model of professors’ job satisfaction with a richness of details was developed.

APA, Harvard, Vancouver, ISO, and other styles

12

Baláž, Ivan, and Martina Zigová. "Flea Communities on Small Mammals in Lowland Environment." Ekológia (Bratislava) 39, no. 3 (September 1, 2020): 260–69. http://dx.doi.org/10.2478/eko-2020-0020.

Full text

Abstract:

AbstractThe landscape of south-western Slovakia is characterised by anthropogenous reshaping, while fragments of undisturbed, waterlogged habitats have been preserved in what remains of the meandering ancient Žitava River. These refuges are inhabited by various small mammal species and their blood-sucking ectoparasites. Between 2014 and 2018, research on them was carried out in Slovakia’s Danubian Lowland (Podunajská nížina) during three out of the four seasons (spring, summer and autumn). The small mammals were captured at 27 localities. The occurrence of nine flee species from the Hystrichopsyllidae, Ctenophthalmidae and Ceratophyllidae families was documented on 12 small burrowing mammals. During the course of all the seasons in which research was conducted, Ctenophthalmus agyrtes, C. assimilis, Megabothris turbidus a Nosopsyllus fasciatus were found, among the most dominant species to be seen on small burrowing mammals.

APA, Harvard, Vancouver, ISO, and other styles

13

Parker, William C., Thomas L. Noland, and Andrée E. Morneault. "Effect of seed mass on early seedling growth of five eastern white pine (Pinus strobus L.) families under contrasting light environments." Canadian Journal of Botany 82, no. 11 (November 1, 2004): 1645–55. http://dx.doi.org/10.1139/b04-129.

Full text

Abstract:

The strong influence of seed mass on early seedling growth of forest tree species is well established, but the ecological role of intraspecific variation in seed mass on natural regeneration is poorly understood. Wide variation in initial spatial patterns of natural regeneration of eastern white pine (Pinus strobus L.) between managed and undisturbed white pine forests of the Great Lakes region of North America has been attributed to differences in understory light levels and the frequency of substrates suitable for germination and seedling establishment. To explore the potential influence of seed mass on these observed patterns, the interaction of seed mass and light on early growth of white pine was investigated in a greenhouse study. Seedlings of five half-sib families differing in mean seed mass were grown for 8 and 14 weeks under moderate and low light conditions representing managed and undisturbed pine stands, respectively. Family differences in seedling biomass and root system development under each light environment were associated with positive, linear relationships with mean seed mass. Family and seed mass had a comparatively weak influence on biomass partitioning and relative growth rate. Moderate light improved seedling growth regardless of seed mass, but relative expression of seed mass effects on seedling traits was unaffected by light environment. These results suggest differential recruitment of white pine in managed and undisturbed stands is unrelated to variation in seed mass.Key words: biomass allocation, eastern white pine, greenhouse experiment, natural regeneration, relative growth rate, seed mass.

APA, Harvard, Vancouver, ISO, and other styles

14

Oh, Sree, Keunho Kim, Joon Hyeop Lee, Minjin Kim, Yun-Kyeong Sheen, Jinsu Rhee, Chang H. Ree, et al. "Impact of galaxy mergers on the colours of cluster galaxies." Monthly Notices of the Royal Astronomical Society 488, no. 3 (July 12, 2019): 4169–80. http://dx.doi.org/10.1093/mnras/stz1920.

Full text

Abstract:

ABSTRACT We examine the ultraviolet and optical colours of 906 cluster galaxies from the KASI-Yonsei Deep Imaging Survey of Clusters (KYDISC). The sample has been divided into two categories, morphologically disturbed and undisturbed galaxies, based on the visual signatures related to recent mergers. We find that galaxies with signatures of recent mergers show significantly bluer colours than undisturbed galaxies. Disturbed galaxies populate more on the cluster outskirts, suggesting recent accretion into the cluster environment, which implies that disturbed galaxies can be less influenced by the environmental quenching process and remain blue. However, we still detect bluer colours of disturbed galaxies in all locations (cluster core and outskirts) for the fixed morphology, which is difficult to understand just considering the difference in time since infall into a cluster. Moreover, blue disturbed galaxies show features seemingly related to recent star formation. Therefore, we suspect that mergers make disturbed galaxies keep their blue colour longer than undisturbed galaxies under the effect of the environmental quenching through either merger-induced star formation or central gas concentration which is less vulnerable for gas stripping.

APA, Harvard, Vancouver, ISO, and other styles

15

Guo, Qinghua, Fuchu Dai, and Zhiqiang Zhao. "Analysis of the Hydraulic Properties of Undisturbed Layered Loess in Northwest China." Water 11, no. 7 (July 4, 2019): 1379. http://dx.doi.org/10.3390/w11071379.

Full text

Abstract:

Extensive agricultural irrigation in the loess region of Northwest China has seriously damaged the local hydrogeological environment. To properly understand the hydrological processes and the hydraulic properties of the layered soil, the field soil column irrigation test, laboratory soil column infiltration test, and undisturbed soil sample hydraulic experiments were carried out. The results showed that the proposed infiltration model can continuously simulate the infiltration process of the loess–palaeosol sequence well. The layered structure may form a temporary groundwater table at the interface of the two different soils under irrigation conditions. This provides a scientific basis for proposing reasonable irrigation measures.

APA, Harvard, Vancouver, ISO, and other styles

16

Pastor, J., A. J. Hernández, M. J. Adarve, and A. Urcelay. "Chemical characteristics of sedimentary soils in the Mediterranean environment: a comparison of undisturbed and disturbed soils." Applied Geochemistry 8 (January 1993): 195–98. http://dx.doi.org/10.1016/s0883-2927(09)80036-x.

Full text

APA, Harvard, Vancouver, ISO, and other styles

17

Cheng, Zhu, Cao Guangyu, Amar Aganovic, and Li Baizhan. "Experimental study of the interaction between thermal plumes and human breathing in an undisturbed indoor environment." Energy and Buildings 207 (January 2020): 109587. http://dx.doi.org/10.1016/j.enbuild.2019.109587.

Full text

APA, Harvard, Vancouver, ISO, and other styles

18

Grundy, W. M., M. K. Bird, D. T. Britt, J. C. Cook, D. P. Cruikshank, C. J. A. Howett, S. Krijt, et al. "Color, composition, and thermal environment of Kuiper Belt object (486958) Arrokoth." Science 367, no. 6481 (February 13, 2020): eaay3705. http://dx.doi.org/10.1126/science.aay3705.

Full text

Abstract:

The outer Solar System object (486958) Arrokoth (provisional designation 2014 MU69) has been largely undisturbed since its formation. We studied its surface composition using data collected by the New Horizons spacecraft. Methanol ice is present along with organic material, which may have formed through irradiation of simple molecules. Water ice was not detected. This composition indicates hydrogenation of carbon monoxide–rich ice and/or energetic processing of methane condensed on water ice grains in the cold, outer edge of the early Solar System. There are only small regional variations in color and spectra across the surface, which suggests that Arrokoth formed from a homogeneous or well-mixed reservoir of solids. Microwave thermal emission from the winter night side is consistent with a mean brightness temperature of 29 ± 5 kelvin.

APA, Harvard, Vancouver, ISO, and other styles

19

Leyte-Manrique, Adrian, Buelna-Chontal Abel Antonio, Torres-Díaz Miguel Alejandro, Christian Berriozabal-Islas, and Carlos Alberto Maciel-Mata. "A Comparison of Amphibian and Reptile Diversity Between Disturbed and Undisturbed Environments of Salvatierra, Guanajuato, Mexico." Tropical Conservation Science 12 (January 2019): 194008291982999. http://dx.doi.org/10.1177/1940082919829992.

Full text

Abstract:

Amphibians and reptiles are two groups of vertebrates that are sensitive to changes in their environment. These changes are mostly caused by human activities, which affect the abundance, composition, and distribution of these vertebrates. In this study, we compare the richness and taxonomic diversity of herpetofauna between undisturbed environments (tropical deciduous forest = TDF) and disturbed environments (corn fields = CF) near the towns of Urireo (URI) and San Nicolas de los Agustinos (SNA) in Salvatierra, Guanajuato. We recorded a total of 19 species in the two locations (4 amphibian and 15 reptile species). At the URI locality, 12 species were recorded in CF and 10 in TDF. At the SNA locality, eight species were recorded in CF and seven species in TDF. In addition, we found that overall taxonomic distinctness was greater at URI than SNA across both types of vegetation, with the highest diversity found in TDF of URI. Seven of the 19 species recorded are current allocated to some protection category of NOM-059-SEMARNAT-2010: Lithobates neovolcanicus, Kinosternon integrum, Sceloporus grammicus, Lampropeltis polyzona, Masticophis mentovarius, Salvadora bairdi, and Thamnophis melanogaster differing from other mechanisms such as the International Union for Conservation of Nature and Environmental Vulnerability Score. Our results suggest that carrying out long-term studies that include diversity and taxonomic distinctness in environments with different levels of disturbance, in addition to including characteristics of natural history, might enhance the development of more efficient conservation strategies for these vertebrates.

APA, Harvard, Vancouver, ISO, and other styles

20

Johnston, C. E., C. Gordillo, and J. G. Eales. "Transition from a hatchery to a laboratory environment induces inner-ring monodeiodination pathways for thyroid hormones in liver of rainbow trout, Oncorhynchus mykiss." Canadian Journal of Zoology 74, no. 12 (December 1, 1996): 2178–83. http://dx.doi.org/10.1139/z96-246.

Full text

Abstract:

In laboratory-acclimated rainbow trout (Oncorhynchus mykiss) the main hepatic deiodination pathway for thyroid hormones is L-thyroxine (T4) outer-ring deiodination (T4ORD), which produces biologically active 3,5,3′-triiodo-L-thyronine (T3); T4 inner-ring deiodination (T4IRD) as well as T3ORD and T3IRD activities are low or undetectable. Surprisingly, trout transported 48 h previously from a local hatchery to the laboratory demonstrated not only low T4ORD activity but also significant T4IRD and T3IRD activities. To test if the transition from hatchery to laboratory environment had induced the unexpected inner-ring deiodinations, we measured hepatic deiodinase activities over the same time frame in trout recently transported to the laboratory and also in trout retained undisturbed at the hatchery. Undisturbed hatchery trout showed typical hepatic deiodinase function: T4ORD activity predominated, while T3IRD, T4IRD, and T3ORD activities were basal. However, after 1–3 days in the laboratory, hepatic T4ORD activity was reduced and T4IRD and T3IRD activities were increased. By 5 days, deiodinase activities of laboratory trout reverted to the levels of hatchery trout. We conclude that physical disturbance can temporarily depress thyroidal status by simultaneously decreasing hepatic production of biologically active T3 and inducing degradation of T4 and T3.

APA, Harvard, Vancouver, ISO, and other styles

21

Latimer, Joyce G., Thalia Pappas, and Cary A. Mitchell. "Growth Responses of Eggplant and Soybean Seedlings to Mechanical Stress in Greenhouse and Outdoor Environments." Journal of the American Society for Horticultural Science 111, no. 5 (September 1986): 694–98. http://dx.doi.org/10.21273/jashs.111.5.694.

Full text

Abstract:

Abstract Eggplant (Solanum melongena L. var. esculentum ‘Burpee's Black Beauty’) and soybean [Glycine max (L.) Merr. ‘Wells II’] seedlings were assigned to a greenhouse or a windless or windy outdoor environment. Plants within each environment received either periodic seismic (shaking) or thigmic (flexing or rubbing) treatments, or were left undisturbed. Productivity (dry weight) and dimensional (leaf area and stem length) growth parameters generally were reduced more by mechanical stress in the greenhouse (soybean) or outdoor-windless environment (eggplant) than in the outdoor windy environment. Outdoor exposure enhanced both stem and leaf specific weights, whereas mechanical stress enhanced only leaf specific weight. Although both forms of controlled mechanical stress tended to reduce node and internode diameters of soybean, outdoor exposure increased stem diameter.

APA, Harvard, Vancouver, ISO, and other styles

22

Walter, Johannes, Dieter Wurz, Stefan Hartig, and Martin Gabi. "Experimental investigation of an annular diffuser for axial fans at different inflow profiles." Thermal Science 21, suppl. 3 (2017): 553–64. http://dx.doi.org/10.2298/tsci160408183w.

Full text

Abstract:

Axial fans are used in power plants for fresh air supply and flue gas transport. A typical configuration consists of an axial fan and annular diffuser which connects the fan to the following piping. In order to achieve a high efficiency of the con-figuration, not only the components have to be optimized but also their interaction. The present study focuses on the diffuser of the configuration. Experiments are performed on a diffuser-piping configuration to investigate the influence of the velocity profile at the fan outlet on the pressure recovery of the configuration. Two different diffuser inlet profiles are generated, an undisturbed profile and a profile with the typical outlet characteristics of a fan. The latter is generated by the superposition of screens in the inlet zone. The tests are conducted at a high Reynolds number (Re ? 4?105). Mean velocity profiles and wall shear stresses are measured with hydraulic methods (Prandtl and Preston tubes). The results show that there is a lack of momentum at the outer wall of the diffuser and high shear stresses at the inner wall in case of the undisturbed inflow profile. For the typical fan outlet profile it is vice versa. There are high wall shear stresses at the outer wall while the boundary layer of the inner wall lacks momentum. The pressure recovery of the undisturbed inflow configuration is in good agreement with other studies.

APA, Harvard, Vancouver, ISO, and other styles

23

Sohrabi, Hadi, Meghdad Jourgholami, Mohammad Jafari, Naghi Shabanian, Rachele Venanzi, Farzam Tavankar, and Rodolfo Picchio. "Soil Recovery Assessment after Timber Harvesting Based on the Sustainable Forest Operation (SFO) Perspective in Iranian Temperate Forests." Sustainability 12, no. 7 (April 3, 2020): 2874. http://dx.doi.org/10.3390/su12072874.

Full text

Abstract:

Minimizing the impact of timber harvesting on forest stands and soils is one of the main goals of sustainable forest operation (SFO). Thus, it is necessary to make an accurate assessment of forest operations on soil that is based on the SFO perspective. The present study was conducted according to SFO principles to investigate the time required for the natural recovery of soil after disturbance by skidding operations in some Iranian forests. The physical, chemical, and biological properties of soil found in abandoned skid trails from different time periods were compared with undisturbed forest soils. The soil bulk density, the penetration resistance, and the microporosity of a 25-year-old skid trail were 8.4–27.4% and 50.4% greater, and the total porosity, macroporosity, and soil moisture were 1.9–17.1% and 4.6% lower than the undisturbed area. In a 25-year-old skid trail, the values of pH, Electrical conductivity (EC), C, N, available P, K, Ca, and Mg, earthworm density, and biomass were lower than in the undisturbed area, and the C/N ratio value was higher than in the undisturbed area. High traffic intensity and slope classes of 20–30% in a three-year-old skid trail had the greatest impact on soil properties. In order to have sustainable timber production, SFO should be developed and soil recovery time should be reduced through post-harvest management operation.

APA, Harvard, Vancouver, ISO, and other styles

24

Àvila, Anna, and Ferran Rodà. "Changes in atmospheric deposition and streamwater chemistry over 25years in undisturbed catchments in a Mediterranean mountain environment." Science of The Total Environment 434 (September 2012): 18–27. http://dx.doi.org/10.1016/j.scitotenv.2011.11.062.

Full text

APA, Harvard, Vancouver, ISO, and other styles

25

Zambetakis - Lekkas, A., and A. Kemeridou. "LOFTUSIA CF. ANATOLICA HORIZON IN UPPER MAASTRICHTIAN LIMESTONES OF THE EASTERN GREECE PLATFORM (MOUNT PTOON, BOEOTIA, GREECE): PALAEOBIOGEOGRAPHICAL REMARKS." Bulletin of the Geological Society of Greece 36, no. 2 (July 23, 2018): 792. http://dx.doi.org/10.12681/bgsg.16818.

Full text

Abstract:

Researches on upper Cretaceous limestones from the Eastern Greece platform in the area between Kokkinon and Akrefnion (Boeotia, Greece) revealed the presence of a horizon rich in Loftusia cf. anatolica (foraminifer). In this horizon, of late Maastrichtian age, L. cf. anatolica is associated with debris of Rudists, Orbitoides media, O. apiculata, O. gensacicus, Siderolites calcitrapoides, Omphalocyclus macroporus, Hellenocyclina beotica, Miliolidae, Dasycladaceae and echinoderms. It is found in an undisturbed sequence of limestones, where both the underlying and the overlying horizons are of the same facies and contain debris of Rudists, Hellenocyclina beotica, Orbitoides media, Siderolites calcitrapoides, Sulcoperculina sp., Rotaliidae, Mélobesiées,Nummofallotia sp., echinoderms. L. cf. anatolica is confined in the above mentioned horizon and it is found neither in the underlying nor in the overlying beds. This fades reflects an outer shelf environment in front of the rudist reefs. It is the first time that this species is reported in situ in Greece in an undisturbed stratigraphie sequence of upper Cretaceous limestones up to Paleocene flysch.

APA, Harvard, Vancouver, ISO, and other styles

26

Engler, Randall. "Heraeus cytomat® 6000 Series Incubators and Storage Systems from Kendro Laboratory Products." JALA: Journal of the Association for Laboratory Automation 5, no. 2 (April 2000): 38–41. http://dx.doi.org/10.1016/s1535-5535-04-00060-7.

Full text

Abstract:

There are a number of cases in high throughput screening systems where a controlled environment is desired. These include incubation periods for cell-based assays, incubation for protein detection assays such as ELISA or fluorescence assays, and branching assays for mRNA detection. In addition, as the density of wells in microplates increases and well volumes become smaller, evaporation becomes a concern in all assays. The cytomat® 6000 is a robot accessible, automated CO2 incubator used for cell-based High Throughput Screening systems. The incubator provides superior environmental conditions, due to the unique access door at the back of the instrument, the PlateShuttle (see Figure 3 ). This small access opening insures that the environment inside the system (temperature, humidity and CO2) is undisturbed as microplates are accessed ( Figure 2 ). The system provides high speed, random (bar-coded) access to all microplate formats for 24, 96, 384 and 1536 well microplates (up to 261-microplate capacity). Other cytomat configurations offer refrigerated and low humidity environments.

APA, Harvard, Vancouver, ISO, and other styles

27

Keen, Peter W., and Mario P. Brito. "Design considerations and solutions in rapid-prototyping an ultraviolet reactor for ice borehole disinfection." Annals of Glaciology 55, no. 65 (2014): 74–82. http://dx.doi.org/10.3189/2014aog65a006.

Full text

Abstract:

AbstractAntarctic subglacial lakes are of great interest to the science community. These systems are considered to be in pristine condition, potentially harbouring an environment containing undisturbed sedimentary sequences and ecosystems adapted to cold oligotrophic environments in the absence of sunlight. Gaining access to subglacial lakes presents major technological challenges. To comply with conventions covering the exploration of pristine Antarctic environments, access should be conducted so the lake is not contaminated in any way. Consequently, all equipment to enter the lake must be sterile and the entrance should isolate the lake from the external environment. Currently, clean access to these environments is achieved using a hot-water drilling system. Differences between the hydraulic pressure head of the lake and the glacial surface result in a section of the borehole being air-filled. It is imperative that this section is disinfected prior to introducing any sampling equipment. This paper describes the design process involved in rapid-prototyping an ultraviolet (UV) disinfection reactor for achieving this goal. Considerations such as UV output, physical constraints, temperature management, and deployment procedures are assessed. We present a design that addresses these considerations.

APA, Harvard, Vancouver, ISO, and other styles

28

A, Ombugadu, Ugwu AR, Ibrahim JI, Dawam NN, Pam VA, Okoi PN, Ahmed HO, et al. "A comparative study on the abundance and diversity of butterflies in disturbed and undisturbed habitats in a tertiary institution in central Nigeria." MOJ Ecology & Environmental Sciences 6, no. 6 (November 10, 2021): 194–99. http://dx.doi.org/10.15406/mojes.2021.06.00233.

Full text

Abstract:

Butterflies are among the most widely spread taxa whose distribution cut across all the continents of the world except the Antarctica. Many butterfly species are comparatively easy to sample and recognize both as individuals and as species than many other insect groups. They are extremely sensitive to changes in vegetation composition and structure in the environment. As a result of this; butterflies have widely been used as a model species to evaluate the health of the environment and changes in the environment. We investigated and compared the butterfly abundance and diversity within a newly established tertiary institution in Central Nigeria in April, 2016 using transects with the aid of sweep nets. Four transects were laid in each of the disturbed and undisturbed habitats of Federal University of Lafia (FULafia). Transects were visited in the morning and evening. An overall total of three hundred and one butterflies were seen. However, only 160 were caught which spread across 5 families, 21 genera and 25 species. The most abundant family of butterflies caught was Pieridae 49 (30.63%) followed by Lycaenidae 42 (26.25%), Nymphalidae 34 (21.25%), Papilionidae 34 (21.25%), while Hesperiidae 1 (0.63%) was the least and scarce in the study area. The most abundant genera of butterflies recorded were Eurema 29 (18.13%), Papilio 27 (16.88%) and Hypolycaena 23 (14.38%). The mean abundance of butterflies seen in relation to disturbed and undisturbed habitats showed a very high significant difference (t = -4.1952, df = 94.682, P < 0.0001). Time of day showed a very high significant difference (t = 6.2208, df = 82.469, P < 0.0001) in the mean abundance of butterflies. The undisturbed habitat was more diversified (H´ = 2.6) in butterfly diversity than the disturbed habitat (H´ = 2.5). This study being the first effort in exploring the butterfly wealth of FULafia clearly shows that the ongoing building construction in the Permanent Site of the University may have some impact on the abundance and diversity of butterflies. Hence, the Management of the Institution should ensure that the area designated for Zoological Garden is well safe guarded for biodiversity conservation amidst ongoing sustainable development.

APA, Harvard, Vancouver, ISO, and other styles

29

Lundquist, Pär, Kjell Holmberg, Lage Burström, and Ulf Landström. "Sound Levels in Classrooms and Effects on Self-Reported Mood among School Children." Perceptual and Motor Skills 96, no. 3_suppl (June 2003): 1289–99. http://dx.doi.org/10.2466/pms.2003.96.3c.1289.

Full text

Abstract:

The principle of this field study is an investigation of recorded sound levels in 24 classrooms and relations between sound level measures and aspects of children's rated annoyance, task orientation, and inattentiveness. The background sound-exposure levels were distributed within the interval of 33–42 dB(A)eq and the activity sound level exposure ranged between 47–68 dB(A)eq. The recorded levels must be considered as high for work environments where steady concentration and undisturbed communication is essential. Results do not support the hypothesis that lower background-sound level and fewer students per class would improve the sound environment by generating a lower activity noise or the hypothesis that higher sound levels should increase annoyance and inattentiveness as well as deteriorate task orientation ratings.

APA, Harvard, Vancouver, ISO, and other styles

30

Kozyreva, E. A., and V. A. Khak. "THE ANTHROPOGENIC CHANGES IN THE GEOLOGICAL ENVIRONMENT IN THE SOUTH OF EAST SIBERIA." Bulletin of the Geological Society of Greece 43, no. 3 (January 24, 2017): 1192. http://dx.doi.org/10.12681/bgsg.11294.

Full text

Abstract:

The investigation results of the geological environment’s condition in an areas marked by high anthropogenic load are described in this paper. In the southern East Siberia the strategy of key sites monitoring is used for this purpose. The selection of key sites is determined by the specific character of geological environment, as well as by the intensity and relationships of developing geological processes. In the studied territory the great variety of exogenic processes can be observed, the majority of them being activated by technogenic factors. To the inherited processes the gravitation, cryogenic and those induced by surface and subsurface water activity belong. In order to estimate the actual condition of the territories and to ensure the undisturbed exploitation of engineering structures, the specific features of lithosphere, the development of exogenic geological processes and the evolution of the anthropogenesis should be taken under consideration.

APA, Harvard, Vancouver, ISO, and other styles

31

Dwivedi, Bharti, and Suchitra Banerjee. "CERTAIN CRITICAL OBSERVATIONS ON MELANOPHORES AS BIOMARKER OF WATER POLLUTION." International Journal of Research -GRANTHAALAYAH 3, no. 9SE (September 30, 2015): 1–5. http://dx.doi.org/10.29121/granthaalayah.v3.i9se.2015.3281.

Full text

Abstract:

Recently, first time in entire cultural history, man has faced one of the most horrible ecological crisis - the problem of pollution of his environment which some time past was pure, virgin, undisturbed, uncontaminated and basically quit hospitable for man. The presence in or introduction into the environment of a substance having harmful or poisonous was felt by man now. Pollution is an undesirable change in physical, chemical or biological properties of air, water and soil, which directly or indirectly affect human beings. (Odum 1971). This may harmfully affect human life or that of desirable species, our industrial processes living conditions and cultural assets. In other words pollution is used to refer harmful materials introduced by man into the environment. Thus in a way, pollution is used to release in excess of permit table limit of foreign substances within the environment (Michal 1984).

APA, Harvard, Vancouver, ISO, and other styles

32

Kant, R., M. A. Minor, S. A. Trewick, and W. R. M. Sandanayaka. "Parasitism and mating of Diaeretiella rapae (Hymenoptera Aphidiidae) in an uncontrolled environment." New Zealand Plant Protection 63 (August 1, 2010): 283. http://dx.doi.org/10.30843/nzpp.2010.63.6599.

Full text

Abstract:

Parasitism and mating activities of Diaeretiella rapae were studied in a shadehouse under ambient environmental conditions during September (early spring) and November (late spring) Before collecting the data the parasitoid and its aphid host colonies were left to develop undisturbed on cabbage seedlings for 3 months in about 25 m2 area The plants were highly infested with aphids (average 27225 aphids/plant) and parasitism by D rapae varied between 25 and 36 during the study period There was no significant change in parasitism rate during the 10week study period (P069) Adult parasitoids emerged from aphid mummies at a rate of more than 90 with a higher number of females than males The mean female/male parasitoid sex ratio was greater in the second 5week (late spring) than the early 5week period (early spring) (P

APA, Harvard, Vancouver, ISO, and other styles

33

Bitenieks, Krišs, Arta Bārdule, Karin Eklöf, Mikk Espenberg, Dainis Edgars Ruņģis, Zane Kļaviņa, Ivars Kļaviņš, Haiyan Hu, and Zane Lībiete. "The Influence of the Degree of Forest Management on Methylmercury and the Composition of Microbial Communities in the Sediments of Boreal Drainage Ditches." Microorganisms 10, no. 10 (October 6, 2022): 1981. http://dx.doi.org/10.3390/microorganisms10101981.

Full text

Abstract:

Inorganic mercury (Hg) can be methylated to the highly toxic and bioavailable methylmercury (MeHg) by microorganisms in anaerobic environments. The Hg methylation rate may be affected by forest management activities, which can influence the catchment soils, water, and sediments. Here, we investigate the influence of forest management in the form of ditch cleaning and beaver dam removal, as well as the seasonal variations, on sediment chemistry and microbiota. The relationships between MeHg concentrations in sediment samples and archaeal and bacterial communities assessed by 16S rRNA gene amplicon sequencing were investigated to determine the microbial conditions that facilitated the formation of MeHg. Concentrations of MeHg were highest in undisturbed catchments compared to disturbed or slightly disturbed sites. The undisturbed sites also had the highest microbial diversity, which may have facilitated the formation of MeHg. Low MeHg concentrations and microbial diversity were observed in disturbed sites, which may be due to the removal of organic sediment layers during ditch cleaning and beaver dam removal, resulting in more homogenous, mineral-rich environments with less microbial activity. MeHg concentrations were higher in summer and autumn compared to winter and spring, but the temporal variation in the composition and diversity of the microbial community was less than the spatial variation between sites. Beta diversity was more affected by the environment than alpha diversity. The MeHg concentrations in the sediment were positively correlated to several taxa, including Cyanobacteria, Proteobacteria, Desulfobacterota, Chloroflexi, and Bacteroidota, which could represent either Hg-methylating microbes or the growth substrates of Hg-methylating microbes.

APA, Harvard, Vancouver, ISO, and other styles

34

Jett, Lewis W. "207 Tillage Methods Affect the Growth of Sweetpotato." HortScience 34, no. 3 (June 1999): 477E—478. http://dx.doi.org/10.21273/hortsci.34.3.477e.

Full text

Abstract:

Growth of the sweetpotato [Ipomoea batatas (L.) Lam.] is subject to environmental variation. High soil temperatures can restrict storage root initiation and development. Moreover, fluctuating soil moisture can have a pronounced effect on yield and quality. Cover crops, used in a conservation tillage system, could modify the soil environment. The objective of this research was to investigate the effects of conservation tillage on sweetpotato growth. A rye cover crop was broadcast seeded in Fall 1996, and sweetpotatoes were transplanted into the undisturbed residue the following spring. A fallow, unseeded plot represented the conventional method of sweetpotato culture. Plants were harvested at 14-day intervals commencing at 21 days after transplanting. Leaf area and dry weights of the storage roots and vines were recorded. Soil moisture was measured by taking soil cores at the depth of rooting (10 cm). The sweetpotatoes growing in the undisturbed rye residue had a significantly greater leaf area, vine weight, root set, and yield (particularly large grade class) relative to conventional-tilled sweetpotatoes. The rye residue was very effective in reducing soil evaporation.

APA, Harvard, Vancouver, ISO, and other styles

35

Budzik, Tomasz. "THE EXAMPLE OF AN INEFFECTIVE CHANGE IN THE COMPANY IN TERMS OF THE HISTORY OF CAR COMMUNICATION ENTERPRISES ACTIVITY." Zeszyty Naukowe Wyższej Szkoły Humanitas Zarządzanie 18, no. 4 (December 28, 2017): 49–60. http://dx.doi.org/10.5604/01.3001.0010.8280.

Full text

Abstract:

Today’s world can be characterized by very high volatility, which affects every sphere of business. Changes occur in both the enterprise and its environment. Changes that can be observed in the company’s environment are characterized by increased pace of production and they have impact on undisturbed operation of the company. Changes in the organization should be the intended and planned. The article presents the essence of change in the company and its surroundings. By using the metod of document examination, the author shows in details the history of Car Transport Enterprises, since their inception in the postwar years, is shown in details, through the influence of the political changes in Poland in the 1990s, up to the present.

APA, Harvard, Vancouver, ISO, and other styles

36

Doytchinov, Vesselin V., and Svetoslav G. Dimov. "Microbial Community Composition of the Antarctic Ecosystems: Review of the Bacteria, Fungi, and Archaea Identified through an NGS-Based Metagenomics Approach." Life 12, no. 6 (June 18, 2022): 916. http://dx.doi.org/10.3390/life12060916.

Full text

Abstract:

Antarctica represents a unique environment, both due to the extreme meteorological and geological conditions that govern it and the relative isolation from human influences that have kept its environment largely undisturbed. However, recent trends in climate change dictate an unavoidable change in the global biodiversity as a whole, and pristine environments, such as Antarctica, allow us to study and monitor more closely the effects of the human impact. Additionally, due to its inaccessibility, Antarctica contains a plethora of yet uncultured and unidentified microorganisms with great potential for useful biological activities and production of metabolites, such as novel antibiotics, proteins, pigments, etc. In recent years, amplicon-based next-generation sequencing (NGS) has allowed for a fast and thorough examination of microbial communities to accelerate the efforts of unknown species identification. For these reasons, in this review, we present an overview of the archaea, bacteria, and fungi present on the Antarctic continent and the surrounding area (maritime Antarctica, sub-Antarctica, Southern Sea, etc.) that have recently been identified using amplicon-based NGS methods.

APA, Harvard, Vancouver, ISO, and other styles

37

Abdul Wahab, Muzamir Hassan, Zaheer Ud Din, and Qamar Uz Zaman. "Heavy metals concentration in undisturbed peat soil at Pekan District, Pahang, West Malaysia." Maejo International Journal of Energy and Environmental Communication 3, no. 2 (August 15, 2021): 23–31. http://dx.doi.org/10.54279/mijeec.v3i2.245731.

Full text

Abstract:

Soil is a mixture of various materials such as air, water, and organic matter. Soft soil (peat) has very deprived physical properties such as low shear strength, high moisture content, high compressibility, and permeability. In an engineering perspective it is considered as a weak soil, while an the agricultural context it is considered as a rich soil because of high amount of carbon. Heavy metals such as arsenic, chromium, cadmium, and lead are considered highly toxic, and it may produce mutagenic, carcinogenic, and genotoxic effects. This study examined the heavy metals concentration of peat soil. There were nine peat samples collected from three different sites which are Kampung Bahru (KB), Kampung Lancang I (KL I), and Kampung Lancang II (KL II), Pekan district, Pahang State, Malaysia. This research indicated that the average organic content were 97.8 % for KB, 95.88 % for KL I, and 98.48 % for KL II approximately for peat soil. It concluded that the concentration of As, Cu, Ni, Pb, and Zn exceeded the standard guidelines, and Mg concentration was observed below the recommended guidelines. It is essential to extract these metals and further assess their toxicological impact on the environment and human health.

APA, Harvard, Vancouver, ISO, and other styles

38

Tortora, C., N. R. Napolitano, M. Radovich, C. Spiniello, L. Hunt, N. Roy, L. Moscardini, et al. "Nature versus nurture: relic nature and environment of the most massive passive galaxies at z < 0.5." Astronomy & Astrophysics 638 (June 2020): L11. http://dx.doi.org/10.1051/0004-6361/202038373.

Full text

Abstract:

Relic galaxies are thought to be the progenitors of high-redshift red nuggets that for some reason missed the channels of size growth and evolved passively and undisturbed since the first star formation burst (at z > 2). These local ultracompact old galaxies are unique laboratories for studying the star formation processes at high redshift and thus the early stage of galaxy formation scenarios. Counterintuitively, theoretical and observational studies indicate that relics are more common in denser environments, where merging events predominate. To verify this scenario, we compared the number counts of a sample of ultracompact massive galaxies (UCMGS) selected within the third data release of the Kilo Degree Survey, that is, systems with sizes Re < 1.5 kpc and stellar masses M⋆ > 8 × 1010 M⊙, with the number counts of galaxies with the same masses but normal sizes in field and cluster environments. Based on their optical and near-infrared colors, these UCMGS are likely to be mainly old, and hence representative of the relic population. We find that both UCMGS and normal-size galaxies are more abundant in clusters and their relative fraction depends only mildly on the global environment, with denser environments penalizing the survival of relics. Hence, UCMGS (and likely relics overall) are not special because of the environment effect on their nurture, but rather they are just a product of the stochasticity of the merging processes regardless of the global environment in which they live.

APA, Harvard, Vancouver, ISO, and other styles

39

Basset, Salomé, Guillaume Heisbourg, Alina Pascale-Hamri, Stéphane Benayoun, and Stéphane Valette. "Effect of Texturing Environment on Wetting of Biomimetic Superhydrophobic Surfaces Designed by Femtosecond Laser Texturing." Nanomaterials 12, no. 18 (September 7, 2022): 3099. http://dx.doi.org/10.3390/nano12183099.

Full text

Abstract:

Inspired by Euphorbia leaves, micrometric pillars are designed on 316L stainless steel surfaces using a femtosecond laser to achieve superhydrophobicity. In this study, we focus on wetting behavior evolution as a function of time and chemical environment. Two types of texturing designs are performed: the laser texturing of micrometric square pillars, and the laser texturing of micrometric square pillars whose tops were irradiated using various fluences to obtain a different topography on the nanometric scale. Two laser texturing environments are considered in both cases: a CO2 flow and ambient air. The main result is that 250 days after laser texturing, steady-state contact angles (SSCA) were above 130° no matter what the environment was. We also study the effect of regular wetting over time. Comparing the results of surfaces for which wetting over time was conducted and that of the undisturbed surfaces for 250 days demonstrates that performing wetting measurements when the surface is not stable led to major changes in droplet behavior. Our surfaces have a unique wettability in which droplets are in an intermediate state. Finally, using a CO2 flow did not help reach higher SSCA, but it limited the effect of regular wetting measurements.

APA, Harvard, Vancouver, ISO, and other styles

40

Seburn, David C., and G. Peter Kershaw. "Changes in the active layer of a subarctic right-of-way as a result of a crude-oil spill." Canadian Journal of Earth Sciences 34, no. 12 (December 1, 1997): 1539–44. http://dx.doi.org/10.1139/e17-125.

Full text

Abstract:

The active layer of three distinct environments (undisturbed forest, moderately disturbed right-of-way, and severely disturbed trench) was examined during each of the 3 years following an experimental crude-oil spill in a black spruce forest in the Northwest Territories. The first year after the spill, the active layer in the oiled forest increased by >150%, in the oiled right-of-way by >80%, and in the oiled trench it did not change. By the third year, the active layers in all oiled environments were significantly deeper than their unoiled counterparts, and the active layer in the oiled trench was significantly deeper than that in the oiled forest. When compared with other studies for a crude-oil spill in a subarctic forested environment, this oil spill caused the greatest increase in thaw depths. This dramatic and persistent increase in thaw depth was likely a function of the high oil concentration, especially in areas where oil had pooled on the ground.

APA, Harvard, Vancouver, ISO, and other styles

41

Das, Abhaya Prasad, Chandra Ghosh, Ajita Sarkar, and Rajib Biswas. "Ethnobotanical studies in India with notes on Terai-Duars and Hills of Darjiling and Sikkim." NBU Journal of Plant Sciences 1, no. 1 (2007): 67–83. http://dx.doi.org/10.55734/nbujps.2007.v01i01.006.

Full text

Abstract:

The very survivability of man is greatly associated with plants since his origin. Plants are responsible for the supply of Man's oxygen, food, medicine, fibre, shelter and what not! Also the relationship between man and environment in general has never been static and is changing continuously. But this is not the case with tribal/ aboriginal communities the world over. The life, culture and traditions of these communities have remained almost undisturbed and static for hundreds of years. They are the living archaeological museums of ancient traditions and cultural heritage of a nation.

APA, Harvard, Vancouver, ISO, and other styles

42

Bodour, Adria A., Kevin P. Drees, and Raina M. Maier. "Distribution of Biosurfactant-Producing Bacteria in Undisturbed and Contaminated Arid Southwestern Soils." Applied and Environmental Microbiology 69, no. 6 (June 2003): 3280–87. http://dx.doi.org/10.1128/aem.69.6.3280-3287.2003.

Full text

Abstract:

ABSTRACT Biosurfactants are a unique class of compounds that have been shown to have a variety of potential applications in the remediation of organic- and metal-contaminated sites, in the enhanced transport of bacteria, in enhanced oil recovery, as cosmetic additives, and in biological control. However, little is known about the distribution of biosurfactant-producing bacteria in the environment. The goal of this study was to determine how common culturable surfactant-producing bacteria are in undisturbed and contaminated sites. A series of 20 contaminated (i.e., with metals and/or hydrocarbons) and undisturbed soils were collected and plated on R2A agar. The 1,305 colonies obtained were screened for biosurfactant production in mineral salts medium containing 2% glucose. Forty-five of the isolates were positive for biosurfactant production, representing most of the soils tested. The 45 isolates were grouped by using repetitive extragenic palindromic (REP)-PCR analysis, which yielded 16 unique isolates. Phylogenetic relationships were determined by comparing the 16S rRNA gene sequence of each unique isolate with known sequences, revealing one new biosurfactant-producing microbe, a Flavobacterium sp. Sequencing results indicated only 10 unique isolates (in comparison to the REP analysis, which indicated 16 unique isolates). Surface tension results demonstrated that isolates that were similar according to sequence analysis but unique according to REP analysis in fact produced different surfactant mixtures under identical growth conditions. These results suggest that the 16S rRNA gene database commonly used for determining phylogenetic relationships may miss diversity in microbial products (e.g., biosurfactants and antibiotics) that are made by closely related isolates. In summary, biosurfactant-producing microorganisms were found in most soils even by using a relatively limited screening assay. Distribution was dependent on soil conditions, with gram-positive biosurfactant-producing isolates tending to be from heavy metal-contaminated or uncontaminated soils and gram-negative isolates tending to be from hydrocarbon-contaminated or cocontaminated soils.

APA, Harvard, Vancouver, ISO, and other styles

43

Fang, Yi, Yuejun Lv, XingYuan Zhou, and Yanju Peng. "Experimental Study of the Engineering Mechanical Properties of the Foundation Soil for Offshore Wind Power Platforms." Shock and Vibration 2021 (October 14, 2021): 1–12. http://dx.doi.org/10.1155/2021/1382740.

Full text

Abstract:

Most of the coastal beach zone in the world is rich in wind energy reserves and has great potential for offshore wind power development. However, the sedimentary environment in the coastal area is complex and changeable, and the nature of the foundation soil of offshore wind power platforms is weak and complex, which is quite different from that in the land areas. In order to systematically study the mechanical properties of marine foundation soils, a series of geotechnical tests are carried out on representative undisturbed seabed soils, such as basic laboratory geotechnical tests, bender element tests, undrained triaxial shear tests, and resonance column tests. The test results show that shear wave velocity (Vs) of marine silt and silty clay increases linearly with the buried depth; the stress-strain relationship curves of silty clay and silt present two different modes of development: strain hardening and strain softening, the undrained shear strength (Sd) of the two types of marine soils decreases with the increase of the void ratio (e), and both present a good single correlation. Based on the relationship between Sd and Vs from the laboratory test of disturbed seabed soils, an undrained strength evaluation method of undisturbed seabed soils under the current stratum conditions incorporating in situ shear wave velocity is established. The dynamic shear modulus (G) in the various strain ranges of undisturbed silty clay and silt increases regularly with the buried depth (H). Meanwhile, the maximum dynamic shear modulus (Gmax) linearly increases with the increase of H, whereas the attenuation relationship of G decreases with the increase of H. The prediction method of G based on buried depth is established with high accuracy.

APA, Harvard, Vancouver, ISO, and other styles

44

Davison, Jennifer L., Robert M. Rauber, Larry Di Girolamo, and Margaret A. LeMone. "A Revised Conceptual Model of the Tropical Marine Boundary Layer. Part I: Statistical Characterization of the Variability Inherent in the Wintertime Trade Wind Regime over the Western Tropical Atlantic." Journal of the Atmospheric Sciences 70, no. 10 (October 1, 2013): 3005–24. http://dx.doi.org/10.1175/jas-d-12-0321.1.

Full text

Abstract:

Abstract This paper investigates wintertime tropical marine boundary layer (TMBL) statistical characteristics over the western North Atlantic using the complete set of island-launched soundings from the Rain in Cumulus over the Ocean (RICO) experiment. The soundings are subdivided into undisturbed and disturbed classifications using two discriminators: 1) dates chosen by Global Energy and Water Cycle Experiment (GEWEX) Cloud System Studies (GCSS) investigators to construct the mean RICO sounding and 2) daily average rain rates. A wide range of relative humidity (RH) values was observed between the surface and 8.0 km. At 2.0 km, half the RH values were within 56%–89%; at 4.0 km, half were within 13%–61%. The rain-rate method of separating disturbed and undisturbed soundings appears more meaningful than the GCSS method. The median RH for disturbed conditions using the rain-rate method showed moister conditions from the surface to 8.0 km, with maximum RH differences of 30%–40%. Moist air generally extended higher on disturbed than undisturbed days. Based on equivalent potential temperature, wind direction, and RH analyses, the most common altitude marking the TMBL top was about 4.0 km. Temperature inversions (over both 50- and 350-m intervals) were observed at every altitude above 1.2 km; there were no dominant inversion heights and most of the inversions were weak. Wind direction analyses indicated that winds within the TMBL originated from more tropical latitudes on disturbed days. The analyses herein suggest that the RICO profile used to initialize many model simulations of this environment represents only a small subset of the broad range of possible conditions characterizing the wintertime trades.

APA, Harvard, Vancouver, ISO, and other styles

45

Robens, E., J. Hauschild, and D. C. Aumann. "Iodine-129 in the environment of a nuclear fuel reprocessing plant: IV. 129I and 127I in undisturbed surface soils." Journal of Environmental Radioactivity 9, no. 1 (January 1989): 17–29. http://dx.doi.org/10.1016/0265-931x(89)90035-0.

Full text

APA, Harvard, Vancouver, ISO, and other styles

46

Mecheri, S., G. Dannecker, D. Dennig, and M. K. Hoffmann. "Immunogenic peptides require an undisturbed phospholipid cell membrane environment and must be amphipathic to immobilize Ia on B cells." Journal of Immunology 144, no. 4 (February 15, 1990): 1369–74. http://dx.doi.org/10.4049/jimmunol.144.4.1369.

Full text

Abstract:

Abstract Ia-reactive immunogenic peptides have been shown to immobilize Ia molecules on the B cell surface and to facilitate their aggregation with specific alloantibody. We show that to immobilize Ia the peptide must be amphipathic. Polar peptides appear to bind to Ia molecules as judged by competitive inhibition, but do not immobilize the MHC molecule. This suggests the possibility that peptides establish the immobilizing membrane contact via a lipophilic group. Examining the B cell membrane lipid environment, we found that treatment of B cells with phospholipase C prevents peptide-mediated immobilization of Ia. The requirement of a lipophilic peptide portion as well as of phospholipase-sensitive membrane components for effective peptide-mediated Ia aggregation on B cell membranes suggests a role for membrane phospholipids in this process. We advance the speculation that immunodominant amphipathic peptides immobilize Ia molecules by attaching them to cell surface phospholipids which we tentatively refer to as immobilizing phospholipids.

APA, Harvard, Vancouver, ISO, and other styles

47

Welham, Clive VJ, and Robert A. Setter. "Comparison of size-dependent reproductive effort in two dandelion (Taraxacum officinale) populations." Canadian Journal of Botany 76, no. 1 (January 1, 1998): 166–73. http://dx.doi.org/10.1139/b97-176.

Full text

Abstract:

Reproductive effort in dandelions (Taraxacum officinale Weber) from two different habitats was compared. One dandelion population occupied a 5-year-old alfalfa (Medicago spp.) field, an environment subject to regular disturbance but with a relatively low density of neighbours. Individuals from the second population were derived from a number of undisturbed sites where the density of neighbouring grasses was high. Three hypotheses were evaluated with respect to the observed patterns of reproductive effort. One hypothesis, that reproductive effort was a function of differences between habitats in resource availability, did not provide an explanation for our results. A second hypothesis considered patterns of reproductive effort when mortality rates varied with degree of disturbance and neighbour density, which was a consequence of each habitat representing a different successional environment. A third hypothesis used a life-history approach to predict reproductive effort when mortality schedules were size dependent. Both of these hypotheses received support for their predictions. There was more than a sixfold variation in reproductive effort among individuals from the alfalfa field and a fourfold variation on the undisturbed sites. Much of this variation, however, was attributable to a size-dependent relationship between reproductive effort and vegetative mass. Total reproductive effort (total seed plus scape mass) in both populations increased linearly with vegetative mass, but the slope for the population from the alfalfa field was significantly higher. In contrast, proportional reproductive effort (total seed plus scape mass per vegetative mass) showed a curvilinear increase for the alfalfa field population but was linear and negative for the undisturbed population. There were also important differences between the populations in reproductive morphology. Larger plants on the alfalfa field had longer average scape lengths, produced more flower heads (capitula) per plant, had greater seed production, and had a lower ratio of seed mass per pappus area; only mean scape and mean seed mass did not differ significantly. We suggest that dandelions on the alfalfa field have a different reproductive morphology to facilitate colonization of open areas on the field.Key words: Taraxacum, dandelion, reproductive effort, biomass, life history, neighbour density, agriculture, weed.

APA, Harvard, Vancouver, ISO, and other styles

48

Andersson, K. G., C. L. Fogh, and J. Roed. "Mobility of Chernobyl137Cs in undisturbed soil : Analysis methods and techniques." Radioprotection 37, no. C1 (February 2002): C1–231—C1–236. http://dx.doi.org/10.1051/radiopro/2002043.

Full text

APA, Harvard, Vancouver, ISO, and other styles

49

Dwyer, Chris P., and Guy A. Baldassarre. "Habitat use by sympatric female mallards and American black ducks breeding in a forested environment." Canadian Journal of Zoology 72, no. 9 (September 1, 1994): 1538–42. http://dx.doi.org/10.1139/z94-204.

Full text

Abstract:

There has been much speculation regarding whether breeding mallards (Anas platyrhynchos) and American black ducks (A. rubripes) use similar habitat types in forested areas, which could lead to increased interspecific contact. To study this issue, we used radiotelemetry during 1990–1991 on sympatric female mallards and black ducks breeding in the western Adirondack Mountains of New York. Mallard and black duck pairs occupied the general area at a density of 0.7 and 0.6/km2, respectively. Black duck home ranges tended to be larger than those of mallards, although the difference was not significant. Habitat composition within the home ranges of mallards and black ducks was similar, upland forest being the dominant habitat type, followed by wetlands, disturbed areas, and active residential sites. Within home ranges, mallards and black ducks were similar in their use of four major wetland habitat types. Our data suggest that undisturbed forest and habitat use within such areas may not serve as an isolating mechanism between breeding mallards and black ducks.

APA, Harvard, Vancouver, ISO, and other styles

50

Bogemans, Frieda, Mathieu Boudin, Rindert Janssens, and Cecile Baeteman. "New data on the sedimentary processes and timing of the initial inundation of Lower Khuzestan (SW Iran) by the Persian Gulf." Holocene 27, no. 4 (October 3, 2016): 613–20. http://dx.doi.org/10.1177/0959683616670224.

Full text

Abstract:

The early- and mid-Holocene deposits of the Lower Khuzestan plain at the north-eastern margin of the Persian Gulf have been investigated by means of facies analysis of sediment successions of undisturbed cores. Organic material and molluscs have been selected for dating by radiocarbon whereby possible contamination by hard-water effect is discussed. The results suggest that the Holocene transgression in Mesopotamia may have taken place later than generally accepted. Before ca. 7700–7900 yr cal. BP, the plain was characterized by mud-dominated fluvial systems. During the mid-Holocene, tides invaded the existing valleys, and the sedimentary environment shifted from fluvial to estuarine but not as extensively as has previously been suggested. The estuarine environments lasted for about 2000–2500 years until ca. 4850–5000 yr cal. BP when the seaward part of the plain was again characterized by widespread fluvial sedimentation.

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Undisturbed environment'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles