The relationship between thermal inertia and degradation state of craters in areas of low surface dust cover on Mars

Icarus ◽  
2021 ◽  
Vol 370 ◽  
pp. 114678
Author(s):  
Chloe B. Beddingfield ◽  
Jeffrey E. Moersch ◽  
Harry Y. McSween
Keyword(s):  
Thermal Inertia ◽  
Surface Dust ◽  
The Relationship ◽  
Degradation State

The relationship between surface dust lead loadings on carpets and the blood lead of young children

1996 ◽  
Vol 18 (4) ◽  
pp. 143-146 ◽  
Author(s):  
Scott Clark ◽  
Robert L. Bornschein ◽  
Winkey Pan ◽  
William Menrath ◽  
Sandy Roda ◽  
...  
Keyword(s):  
Young Children ◽  
Blood Lead ◽  
Surface Dust ◽  
The Relationship

scholarly journals Size-dependent modification of asteroid family Yarkovsky V-shapes

2018 ◽  
Vol 611 ◽  
pp. A82 ◽  
Author(s):  
B. T. Bolin ◽  
A. Morbidelli ◽  
K. J. Walsh
Keyword(s):  
Size Dependence ◽  
Drift Rate ◽  
Thermal Inertia ◽  
Major Axis ◽  
Main Belt ◽  
Semi Major Axis ◽  
Size Dependent ◽  
Dependent Modification ◽  
The Relationship ◽  
Asteroid Families

Context. The thermal properties of the surfaces of asteroids determine the magnitude of the drift rate cause by the Yarkovsky force. In the general case of Main Belt asteroids, the Yarkovsky force is indirectly proportional to the thermal inertia, Γ. Aims. Following the proposed relationship between Γ and asteroid diameter D, we find that asteroids’ Yarkovsky drift rates might have a more complex size dependence than previous thought, leading to a curved family V -shape boundary in semi-major axis, a, vs. 1/D space. This implies that asteroids are drifting faster at larger sizes than previously considered decreasing on average the known ages of asteroid families. Methods. The V-Shape curvature is determined for >25 families located throughout the Main Belt to quantify the Yarkovsky size-dependent drift rate. Results. We find that there is no correlation between family age and V -shape curvature. In addition, the V -shape curvature decreases for asteroid families with larger heliocentric distances suggesting that the relationship between Γ and D is weaker in the outer MB possibly due to homogenous surface roughness among family members.

Particle Flushing and Migration Regularity by Runoff in Different Functional Districts of Beijing City

2011 ◽  
Vol 90-93 ◽  
pp. 1511-1516
Author(s):  
Jian Long Wang ◽  
Wei Feng ◽  
Wu Che ◽  
Tian Sun
Keyword(s):  
Particle Size ◽  
Pollution Control ◽  
Filter Design ◽  
Size Variation ◽  
Beijing City ◽  
Surface Dust ◽  
Rainwater Runoff ◽  
Runoff Pollution Control ◽  
And Migration ◽  
The Relationship

In order to obtain runoff particle flushing and migration regularity in different functional districts, surface runoff and dust of the campus, sidewalk, business street and viaduct in Beijing city were selected as research objects. Through the particle size distribution detection of surface dust and instantaneous rainwater runoff samples, the runoff particle flushing and migration regularity in different functional districts were analyzed. The relationship between runoff particulate and COD, SS, TN, TP and other pollutants, the particle size variation regularity in the flushing and migration process were analyzed, and the reasons were construed too. The results of the runoff pollutants impact of different size particles will provide a theoretical basis for the filter design and urban runoff pollution control planning.

Gullies on Mars and seasonal ices visualised using the Colour and Stereo Surface Imaging System (CaSSIS)

2020 ◽  
Author(s):  
Susan Conway ◽  
Antoine Pommerol ◽  
Jan Raack ◽  
Meven Philippe ◽  
Alfred Mcewen ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Imaging System ◽  
Thermal Inertia ◽  
Surface Expression ◽  
Martian Surface ◽  
Water Ice ◽  
Sequence Of Events ◽  
Continuous Slab ◽  
Time Of Year ◽  
The Relationship

<p>Young gullies on Mars were first reported by Malin and Edgett in 2000 and were hailed as evidence of recent liquid water flows on Mars. Since that time, monitoring of gullies has revealed they are active today at times of year when the martian surface is at its coldest and when carbon dioxide ice is condensed on to the surface. In order to further explore the relationship between surface frosts and gully-activity we focus on Sisyphi Cavi near the south pole of Mars, where gully-activity has already been studied and CaSSIS obtained a dense temporal coverage in 2018. We identified the following sequence of events:</p><p>1) In winter frost covers all surfaces and dark spots and flows can be seen across the slopes with gullies and preferentially around the gully channels. This is consistent with previous observations and has been interpreted to be the surface expression of gas-jets generated by the sublimation of CO<sub>2</sub> underneath a continuous slab of CO<sub>2</sub> ice on the surface. The jets occur when the pressure fractures the slab ice and the pressurized gas can escape with entrained particles.</p><p>2) As the surface temperature increases towards 200 K, the top of the slopes are the first to defrost followed by sun facing parts of the alcoves and channels.</p><p>3) As the surface temperature approaches and exceeds 250 K and the surrounding terrain is completely defrosted, the last parts of the gully to remain frost covered are the fans. We interpret this to be a result of the fans having slightly lower thermal inertia than the surrounding materials. This lower thermal inertia could be because the fans have a lower content of water ice (i.e. a thicker lag on top of the ice-table), because of recent depositional events. It is at this time of year when gullies are most active. Hence, we infer that gully activity increases when there is both frosted and defrosted surfaces available to drive vigorous sublimation of the CO<sub>2</sub> ice.</p><p>4) Finally, once defrosting has almost fully completed and surface temperatures have reached their seasonal maximum of ~270 K the only remaining surface frosts are in pole-facing niches at the base of gully-alcoves.</p><p>Our study has underlined that the colour capability of the CaSSIS instrument is particularly suited to studying and monitoring changes in surface ices. Our observations reveal that gully-alcoves defrost before the fans and gullies defrost later than surrounding terrain – suggesting activity is driven by the availability of “hot” sediment to trigger more efficient sublimation. Further work will examine whether surface frost patterns differ between gullies that have been shown to be active and inactive since spacecraft observations began.</p>

Interstellar gas in the central region of the Galaxy

1967 ◽  
Vol 31 ◽  
pp. 239-251 ◽  
Author(s):  
F. J. Kerr
Keyword(s):  
Central Region ◽  
Galactic Plane ◽  
Neutral Hydrogen ◽  
Continuum Emission ◽  
Galactic Centre ◽  
Interstellar Gas ◽  
Hydrogen Recombination ◽  
The Galaxy ◽  
Centre Region ◽  
The Relationship

A review is given of information on the galactic-centre region obtained from recent observations of the 21-cm line from neutral hydrogen, the 18-cm group of OH lines, a hydrogen recombination line at 6 cm wavelength, and the continuum emission from ionized hydrogen.Both inward and outward motions are important in this region, in addition to rotation. Several types of observation indicate the presence of material in features inclined to the galactic plane. The relationship between the H and OH concentrations is not yet clear, but a rough picture of the central region can be proposed.

The relationship of the scleractinian corals to the rugose corals

Paleobiology ◽  
1980 ◽  
Vol 6 (02) ◽  
pp. 146-160 ◽  
Author(s):  
William A. Oliver
Keyword(s):  
Critical Points ◽  
Scleractinian Corals ◽  
Convincing Evidence ◽  
Early Triassic ◽  
Rugose Corals ◽  
History Of ◽  
The Subject ◽  
Relationship Of ◽  
The Relationship ◽  
Biologic Factors

The Mesozoic-Cenozoic coral Order Scleractinia has been suggested to have originated or evolved (1) by direct descent from the Paleozoic Order Rugosa or (2) by the development of a skeleton in members of one of the anemone groups that probably have existed throughout Phanerozoic time. In spite of much work on the subject, advocates of the direct descent hypothesis have failed to find convincing evidence of this relationship. Critical points are:(1) Rugosan septal insertion is serial; Scleractinian insertion is cyclic; no intermediate stages have been demonstrated. Apparent intermediates are Scleractinia having bilateral cyclic insertion or teratological Rugosa.(2) There is convincing evidence that the skeletons of many Rugosa were calcitic and none are known to be or to have been aragonitic. In contrast, the skeletons of all living Scleractinia are aragonitic and there is evidence that fossil Scleractinia were aragonitic also. The mineralogic difference is almost certainly due to intrinsic biologic factors.(3) No early Triassic corals of either group are known. This fact is not compelling (by itself) but is important in connection with points 1 and 2, because, given direct descent, both changes took place during this only stage in the history of the two groups in which there are no known corals.

Choosing a Markov blanket

2020 ◽  
Vol 43 ◽  
Author(s):  
Thomas Parr
Keyword(s):  
Markov Blanket ◽  
Target Article ◽  
The Relationship

Abstract This commentary focuses upon the relationship between two themes in the target article: the ways in which a Markov blanket may be defined and the role of precision and salience in mediating the interactions between what is internal and external to a system. These each rest upon the different perspectives we might take while “choosing” a Markov blanket.

Tinkering with cognitive gadgets: Cultural evolutionary psychology meets active inference

2019 ◽  
Vol 42 ◽  
Author(s):  
Paul Benjamin Badcock ◽  
Axel Constant ◽  
Maxwell James Désormeau Ramstead
Keyword(s):  
Evolutionary Psychology ◽  
Research Program ◽  
Active Inference ◽  
Innovative Research ◽  
Cognitive Faculties ◽  
Cultural Evolutionary ◽  
The Relationship

Abstract Cognitive Gadgets offers a new, convincing perspective on the origins of our distinctive cognitive faculties, coupled with a clear, innovative research program. Although we broadly endorse Heyes’ ideas, we raise some concerns about her characterisation of evolutionary psychology and the relationship between biology and culture, before discussing the potential fruits of examining cognitive gadgets through the lens of active inference.

Radiation Damage, Contrast and Statistics in High Resolution Biological Electron Microscopy

1970 ◽  
Vol 28 ◽  
pp. 260-261
Author(s):  
Robert M. Glaeser
Keyword(s):  
High Resolution ◽  
Particle Flux ◽  
Unit Area ◽  
Signal To Noise ◽  
Resolution Image ◽  
High Resolution Image ◽  
Pass Through ◽  
Counting Statistics ◽  
The Relationship ◽  
Picture Element

It is well known that a large flux of electrons must pass through a specimen in order to obtain a high resolution image while a smaller particle flux is satisfactory for a low resolution image. The minimum particle flux that is required depends upon the contrast in the image and the signal-to-noise (S/N) ratio at which the data are considered acceptable. For a given S/N associated with statistical fluxtuations, the relationship between contrast and “counting statistics” is s131_eqn1, where C = contrast; r2 is the area of a picture element corresponding to the resolution, r; N is the number of electrons incident per unit area of the specimen; f is the fraction of electrons that contribute to formation of the image, relative to the total number of electrons incident upon the object.

Skeletal elements of crinoid echinoderms: High-resolution structural and microanalytical results

1983 ◽  
Vol 41 ◽  
pp. 194-195
Author(s):  
D. F. Blake ◽  
L. F. Allard ◽  
D. R. Peacor
Keyword(s):  
High Resolution ◽  
Marine Invertebrates ◽  
Sea Urchins ◽  
Structural Features ◽  
Sea Stars ◽  
High Resolution Tem ◽  
Relationship Of ◽  
The Relationship ◽  
Insight Into

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.

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