scholarly journals Localized bank collapse or regional event?

2021 ◽  
Vol 8 ◽  
pp. 27-44
Author(s):  
Charlotte Priddy ◽  
Amy Regis ◽  
Stuart Clarke ◽  
A. Leslie ◽  
Thomas Dodd
Keyword(s):  
Regional Distribution ◽  
Structural Features ◽  
Lower Jurassic ◽  
Spatial Proximity ◽  
Local Source ◽  
Linear Arrangement ◽  
Transport Distance ◽  
Depositional Processes ◽  
Close Spatial Proximity ◽  
Stratigraphic Interval

This study presents a detailed synopsis of the sedimentological and structural features displayed within an underdescribed enigmatic facies observed in the basal Lower Jurassic Kayenta Formation of the Colorado Plateau. The facies comprises pebble to cobble-sized clasts of fine to medium-grained crossbedded sandstone with mud-draped and deformed foresets, as well as clasts of parallel-laminated but highly contorted siltstone and mudstone, supported in a silty to sandy matrix. The deposits are internally deformed and show both ductile and brittle structures in close spatial proximity, with a consistent and pervasive westdirected sense of shear. The facies occurs consistently within the same approximate stratigraphic interval, at or near the base of the Kayenta Formation. It is, however, observed only at four localities, distributed in a crudely linear arrangement parallel to the Utah-Idaho trough, despite extensive studies of outcrops of the same stratigraphic interval widely distributed across both Utah and Arizona. This study interprets the depositional processes as that of a partially subaerial debris flow with depositional events perhaps taking place during the waning period after ephemeral stream activity. The clast morphology and composition suggests a local source for the sediment entrained within the flow, and a limited transport distance. All of these observations are difficult to reconcile with the consistency of the stratigraphic interval in which the facies occur, or with the regional distribution of preserved examples. Consequently, this study discusses the potential for a common and time-equivalent triggering mechanism across all examples, which may have regional significance in the Jurassic evolution of the region.

scholarly journals Involvement of loop 5 lysine residues and the N-terminal β-hairpin of the ribotoxin hirsutellin A on its insecticidal activity

2016 ◽  
Vol 397 (2) ◽  
pp. 135-145 ◽  
Author(s):  
Miriam Olombrada ◽  
Lucía García-Ortega ◽  
Javier Lacadena ◽  
Mercedes Oñaderra ◽  
José G. Gavilanes ◽  
...  
Keyword(s):  
Active Sites ◽  
Structural Changes ◽  
The Other ◽  
Spatial Proximity ◽  
Ribonucleolytic Activity ◽  
The Family ◽  
Lysine Residues ◽  
Hirsutella Thompsonii ◽  
Close Spatial Proximity ◽  
High Degree

Abstract Ribotoxins are cytotoxic members of the family of fungal extracellular ribonucleases best represented by RNase T1. They share a high degree of sequence identity and a common structural fold, including the geometric arrangement of their active sites. However, ribotoxins are larger, with a well-defined N-terminal β-hairpin, and display longer and positively charged unstructured loops. These structural differences account for their cytotoxic properties. Unexpectedly, the discovery of hirsutellin A (HtA), a ribotoxin produced by the invertebrate pathogen Hirsutella thompsonii, showed how it was possible to accommodate these features into a shorter amino acid sequence. Examination of HtA N-terminal β-hairpin reveals differences in terms of length, charge, and spatial distribution. Consequently, four different HtA mutants were prepared and characterized. One of them was the result of deleting this hairpin [Δ(8-15)] while the other three affected single Lys residues in its close spatial proximity (K115E, K118E, and K123E). The results obtained support the general conclusion that HtA active site would show a high degree of plasticity, being able to accommodate electrostatic and structural changes not suitable for the other previously known larger ribotoxins, as the variants described here only presented small differences in terms of ribonucleolytic activity and cytotoxicity against cultured insect cells.

scholarly journals ‘They Eat Potatoes, I Eat Rice’: Symbolic Boundary Making and Space in Neighbour Relations

2011 ◽  
Vol 16 (4) ◽  
pp. 22-33 ◽  
Author(s):  
Gwen Van Eijk
Keyword(s):  
Personal Information ◽  
Spatial Proximity ◽  
Easy Access ◽  
Symbolic Boundaries ◽  
Personal Privacy ◽  
Social Mixing ◽  
Boundary Making ◽  
Close Spatial Proximity ◽  
Depth Interviews ◽  
Symbolic Boundary

This article examines ‘neighbouring’ as the setting in which cross-category relations develop and symbolic boundaries are constructed. The study is based on thirty in-depth interviews with residents living in a multi-ethnic and a mono-ethnic neighbourhood in Rotterdam, the Netherlands. The findings challenge the hoped-for outcomes of social mixing in neighbourhoods, as well as the view that boundary making is something inherent to multi-ethnic neighbourhoods only. Neighbour relations are often setting-specific (relations are interchangeable, scripted and bounded, and passively maintained), which is relevant for understanding the spatiality of neighbouring and the limited exchange of personal information between neighbours. Because neighbouring involves the balancing of personal privacy and close spatial proximity, the exchange of personal information is limited, while spatial proximity ensures easy access to observable (through seeing, hearing and smelling) categorical markers that signify class, ethnicity, lifestyle, etc. In this way, neighbour interaction reconstructs symbolic boundaries rather than breaking them down.

Ontogeny of spatial relationships and social behaviour in juvenile Richardson's ground squirrels

1981 ◽  
Vol 59 (9) ◽  
pp. 1666-1676 ◽  
Author(s):  
Gail R. Michener
Keyword(s):  
Social Interactions ◽  
Social Behaviour ◽  
Ground Squirrels ◽  
Spatial Proximity ◽  
Family Unit ◽  
Social Patterns ◽  
Rapid Acquisition ◽  
The Family ◽  
Core Areas ◽  
Close Spatial Proximity

The development of spatial and social patterns by juvenile Richardson's ground squirrels, from first emergence from the natal burrow to entry into hibernation, is described. Juveniles enter the aboveground population at [Formula: see text] weeks of age. During the next 4 weeks juveniles remain in close spatial proximity to family members with whom they engage in frequent amicable social interactions. Thereafter, juveniles become increasingly independent from the family unit, establishing their own spatially distinct core areas and exhibiting site-dependent dominance toward nonkin. Typically juveniles remain physically closer to and more amicable with littermates and mother than other conspecifics such that they compose kin clusters, the members of which are agonistic toward members of adjacent kin clusters. Daughters are more likely to continue to reside close to kin as adults than are sons. At 9–10 weeks of age juveniles exhibit the majority of spatial and social patterns characteristic of adults, and at 12 weeks they are behaviourally indistinguishable from adults. Similar rapid acquisition of adult patterns occurs in four other species of ground-dwelling sciurids that are also obligate hibernators and that breed immediately following emergence from their first hibernation.

scholarly journals Adenine DNA methylation, 3D genome organization, and gene expression in the parasiteTrichomonas vaginalis

2020 ◽  
Vol 117 (23) ◽  
pp. 13033-13043
Author(s):  
Ayelen Lizarraga ◽  
Zach Klapholz O’Brown ◽  
Konstantinos Boulias ◽  
Lara Roach ◽  
Eric Lieberman Greer ◽  
...  
Keyword(s):  
Gene Expression ◽  
Dna Methylation ◽  
Trichomonas Vaginalis ◽  
Three Dimensional ◽  
Wide Distribution ◽  
Spatial Proximity ◽  
Regulation Of Transcription ◽  
3D Genome ◽  
Intergenic Regions ◽  
Close Spatial Proximity

Trichomonas vaginalisis a common sexually transmitted parasite that colonizes the human urogenital tract causing infections that range from asymptomatic to highly inflammatory. Recent works have highlighted the importance of histone modifications in the regulation of transcription and parasite pathogenesis. However, the nature of DNA methylation in the parasite remains unexplored. Using a combination of immunological techniques and ultrahigh-performance liquid chromatography (UHPLC), we analyzed the abundance of DNA methylation in strains with differential pathogenicity demonstrating that N6-methyladenine (6mA), and not 5‐methylcytosine (5mC), is the main DNA methylation mark inT. vaginalis. Genome-wide distribution of 6mA reveals that this mark is enriched at intergenic regions, with a preference for certain superfamilies of DNA transposable elements. We show that 6mA inT. vaginalisis associated with silencing when present on genes. Interestingly, bioinformatics analysis revealed the presence of transcriptionally active or repressive intervals flanked by 6mA-enriched regions, and results from chromatin conformation capture (3C) experiments suggest these 6mA flanked regions are in close spatial proximity. These associations were disrupted when parasites were treated with the demethylation activator ascorbic acid. This finding revealed a role for 6mA in modulating three-dimensional (3D) chromatin structure and gene expression in this divergent member of the Excavata.

Spatiotemporal factors influence sound-source segregation in localization behavior

2020 ◽  
Author(s):  
Guus Christian van Bentum ◽  
Marc Mathijs van Wanrooij ◽  
A. John Van Opstal
Keyword(s):  
Temporal Order ◽  
Weighted Average ◽  
Spatial Separation ◽  
Stimulus Location ◽  
Spatial Proximity ◽  
Sound Source Segregation ◽  
Close Spatial Proximity ◽  
Inhibitory Interactions ◽  
Localization Behavior ◽  
Sensorimotor Map

To program a goal-directed response in the presence of acoustic reflections, the audio-motor system should suppress the detection of time-delayed sources. We examined the effects of spatial separation and inter-stimulus delay on the ability of human listeners to localize a pair of broadband sounds in the horizontal plane. Participants indicated how many sounds were heard and where these were perceived by making one or two head-orienting localization responses. Results suggest that perceptual fusion of the two sounds depends on delay and spatial separation. Leading and lagging stimuli in close spatial proximity required longer stimulus delays to be perceptually separated than those further apart. Whenever participants heard one sound, their localization responses for synchronous sounds were oriented to a weighted average of both source locations. For short delays, responses were directed towards the leading stimulus location. Increasing spatial separation enhanced this effect. For longer delays, responses were again directed towards a weighted average. When participants perceived two sounds, the first and the second response were directed to either of the leading and lagging source locations. Perceived locations were interchanged often in their temporal order (in ~40% of trials). We show that the percept of two sounds occurring requires sufficient spatiotemporal separation, after which localization can be performed with high accuracy. We propose that the percept of temporal order of two concurrent sounds results from a different process than localization, and discuss how dynamic lateral excitatory-inhibitory interactions within a spatial sensorimotor map could explain the findings.

scholarly journals The Tiskilwa Till, a Regional View of its Origin and Depositional Processes

1981 ◽  
Vol 2 ◽  
pp. 176-182 ◽  
Author(s):  
Susan Specht Wickham ◽  
W. Hilton Johnson
Keyword(s):  
Thermal Regime ◽  
Controlling Factor ◽  
Local Source ◽  
Source Areas ◽  
Depositional Processes ◽  
Red Color ◽  
Major Controlling Factor ◽  
Late Wisconsinan

The Tiskilwa Till Member of the Wedron Formation represents deposition by basal melt-outin the marginal area of the Laurentide ice sheetduring the Woodfordian (late-Wisconsinan) in Illinois. Distinctive characteristics include: a very thick, homogeneous till; relatively little ablation till; red color; sandy texture; illite content that is relatively low withrespect to other Woodfordian tills; and the presence of discontinuous basal zones of differing composition.Erosion and entrainment of debris from both distant and local source areas are evident in the Tiskilwa Jill. Basal thermal regime is suggested as a major controlling factor on the location of the zones of entrainment. The debris was homogenized en route to the margin and eventually was deposited as basal melt-out till near the margin. Deposition occurred within an interval of 6 ka or more during the first half of the Woodfordian.

Radiation dose and image quality inK-edge subtraction computed tomography of lungin vivo

2014 ◽  
Vol 21 (6) ◽  
pp. 1305-1313 ◽  
Author(s):  
S. Strengell ◽  
J. Keyriläinen ◽  
P. Suortti ◽  
S. Bayat ◽  
A. R. A. Sovijärvi ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Image Quality ◽  
Radiation Dose ◽  
Signal To Noise Ratio ◽  
Regional Distribution ◽  
Lung Ventilation ◽  
Structural Features ◽  
Reconstruction Algorithms ◽  
Human Thorax

K-edge subtraction computed tomography (KES-CT) allows simultaneous imaging of both structural features and regional distribution of contrast elements inside an organ. Using this technique, regional lung ventilation and blood volume distributions can be measured experimentallyin vivo. In order for this imaging technology to be applicable in humans, it is crucial to minimize exposure to ionizing radiation with little compromise in image quality. The goal of this study was to assess the changes in signal-to-noise ratio (SNR) of KES-CT lung images as a function of radiation dose. The experiments were performed in anesthetized and ventilated rabbits using inhaled xenon gas in O2at two concentrations: 20% and 70%. Radiation dose, defined as air kerma (Ka), was measured free-in-air and in a 16 cm polymethyl methacrylate phantom with a cylindrical ionization chamber. The dose free-in-air was varied from 2.7 mGy to 8.0 Gy. SNR in the images of xenon in air spaces was above the Rose criterion (SNR > 5) whenKawas over 400 mGy with 20% xenon, and over 40 mGy with 70% xenon. Although in human thorax attenuation is higher, based on these findings it is estimated that, by optimizing the imaging sequence and reconstruction algorithms, the radiation dose could be further reduced to clinically acceptable levels.

scholarly journals Social structure and residency in aggregations of male sperm whales

2002 ◽  
Vol 80 (7) ◽  
pp. 1189-1196 ◽  
Author(s):  
Erland Lettevall ◽  
Christoph Richter ◽  
Nathalie Jaquet ◽  
Elizabeth Slooten ◽  
Steve Dawson ◽  
...  
Keyword(s):  
Social Structure ◽  
Social Structures ◽  
Spatial Proximity ◽  
Residence Times ◽  
Physeter Macrocephalus ◽  
Sperm Whales ◽  
Apparent Lack ◽  
Male Sperm ◽  
Close Spatial Proximity

Sperm whales (Physeter macrocephalus) are sexually dimorphic in several respects, including size, latitudinal distribution, and social structure. Females are known to have complex social structures, including long-term bonds, but the social structures of sexually mature or maturing males have received much less attention. Using data from aggregations of males off Norway, Nova Scotia, New Zealand, and the Galápagos Islands, we examined aggregation size, residence times within aggregations, clustering at the surface, and long-term bonds. Results were generally consistent among study areas. The aggregations found in each area contained around 10–30 males at any time, and were usually a few tens of kilometres across. Mean residence times within aggregations ranged from a few days to a few weeks. Close clustering at the surface was rare, but present at each site. There was no evidence for preferred companionship between individuals at any temporal scale in any of the study areas. The rarity of clustering and the apparent lack of long-term relationships amongst male sperm whales contrast strongly with results of studies on females, suggesting that both close spatial proximity at the surface and permanent bonds between individuals may be a consequence of the need for care of the young.

scholarly journals Depositional environment and burial history of a Lower Cretaceous carbonaceous claystone, Bornholm, Denmark

1996 ◽  
Vol 43 ◽  
pp. 133-142
Author(s):  
H. I. Petersen ◽  
J. A. Bojesen Koefoed ◽  
H. P. Nytoft
Keyword(s):  
Organic Matter ◽  
Lower Cretaceous ◽  
Depositional Environment ◽  
Lower Jurassic ◽  
Plant Litter ◽  
Burial History ◽  
Transport Distance ◽  
Geochemical Parameters ◽  
Kerogen Type ◽  
History Of

A c. 1 m thick carbonaceous claystone from the type locality of the Lower Cretaceous Skyttegård Member (Rabekke Formation), Bornholm, has been investigated by organic pétrographie and organic geochemical methods in order to assess the depositional environment of the claystone and the thermal maturity of the organic matter. The claystone was deposited in a low-energy, anoxic lake which occasionally was marine influenced. The organic matter is terrestrial and can be classified as kerogen type III and lib. Detrital organic matter and cutinite are characteristic components. The organic matter is allochthonous but the transport distance was short, and the plant material was probably mainly derived from plants growing at the edge of, or nearto, the lake. Source-specific biomarkers such as norisopimarane suggest that the plant litter was derived from a gymnospermous, low-diversity vegetation. Evidence for early angiospermous plants cannot be demonstrated with any certainty. A huminite reflectance value of 0.24%Rm and several geochemical parameters indicate that the organic matter is highly immature. It has only experienced coalification corresponding to the peat stage. Estimates show that, prior to uplift, the claystone was buried to a maximum of approximately 260 m. Reflectance data further suggest that a maximum c. 550 m thick sediment package was removed by erosion prior to deposition of the ?uppermost Jurassic-Lower Cretaceous sediments on Lower Jurassic strata.

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