Complex Interior Research Articles

True polar wander of Ceres due to heterogeneous crustal density

Ceres is the largest body in the main asteroid belt. It was recently explored by the Dawn mission to uncover strong similarities with other icy bodies. The morphological features observed on the surface of Ceres indicate a relatively wide range of water ice concentrations, leading us to investigate the magnitude and distribution of crustal density heterogeneities, and to consider whether they could have caused a reorientation of Ceres. Here, we present three independent and corroborating lines of evidence for the true polar wander of Ceres. Thanks to the global gravity inversion approach applied to the shape and gravity data of Ceres, we find crustal density heterogeneities up to approximately ±0.3 g cm−3, with a prominent positive density anomaly aligned with the equator, in the region of Ahuna Mons. The topography shows the remnants of an equatorial ridge compatible with the position of the palaeo-equator, and indicates that Ceres reoriented by approximately 36°, with the palaeo-pole following an indirect path to the current pole of Ceres. The tectonic patterns generated by the true polar wander are in close agreement with the location and orientation of the Samhain Catenae and Uhola Catenae crustal fractures. These results highlight the complex interior structure and richness of processes taking place in Ceres-scale icy bodies. The dwarf planet Ceres may have reoriented in the past due to a heterogeneously dense crust, a scenario consistent with gravity and topographic data and the distribution of crustal fractures.

Land use mapping based on composite regions in aerial images

ABSTRACTLand use data are widely applied for the analysis and management of social, economic, and ecological conditions and are in great demand due to the rapid changes of landscapes. Remote sensing images with high spatial resolutions, especially the aerial ones, are popularly utilized as data sources for large-scale, highly accurate land use mapping. However, unlike simple land cover classes, land use areas are compound with miscellaneous terrestrial objects, which presents the automatic land use mapping with new challenges. In this study, we analysed the characteristics of land uses in high-resolution aerial images and found that the highly complex composition of land use areas causes an individual terrestrial object alone insufficient to determine its land use type. To address this issue, we proposed the concept of Composite Regions as regions formed by diverse objects sharing the same land use type. We defined Geographic Context which is the key determinant for land use mapping. Additionally, three Geographic Contextual features describing different aspects of the Composite Regions were developed: (1) Class Index Area Ratio (CIAR) for spectral distribution, (2) Density Level Area Ratio (DLAR) for scale range, and (3) Class Boundary Length Ratio (CBLR) for semantic affinity. These features take advantage of Earth’s Mover Distance as the proper metric function. The accompanying mapping strategy is formulated by applying CIAR, DLAR, and CBLR in an ordered way, and it involves Fuzzy Object Merging to ensure convincing and sufficient neighbourhood information for objects before final identification. The experiments were performed on aerial images acquired in Zhejiang province, China. The landscapes in the study areas consist of five major land use types and exhibits typical complex interiors which were used to be recognized manually. The mapping results successfully extracted land use areas that were highly consistent with visual interpreted data, despite the complex heterogeneous composition. Assessment analysis also showed high accuracies which validated the effectiveness of the methodology.

Metal-Organic Framework-Derived Co3O4/Au Heterostructure as a Catalyst for Efficient Oxygen Reduction.

Porous nanostructures with a yolk-shell complex interior will provide lots of virtues to construct advanced catalysts. In our work, the preparation of novel yolk-shell Au nanocrystal-loaded Co3O4 nanocages (Co3O4/Au heterostructure) from a metal-organic framework-derived composite was reported. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller analysis, and so forth were used to analyze the morphology, structure, and composition of the heterostructures. Most importantly, Co3O4/Au heterostructures are a kind of low-cost, good performance catalysts for the oxygen reduction reaction to replace the noble-Pt catalysts. The high surface area of the porous structure and the excellent electron transfer properties of well-dispersed Au nanocrystals and also the electronic coupling effect between Co3O4 and Au in the composites are attributed to the good performance.

Development and characterization of a high-efficiency, aircraft-based axial cyclone cloud water collector

A new aircraft-mounted probe for collecting samples of cloud water has been designed, fabricated, and extensively tested. Following previous designs, the probe uses inertial separation to remove cloud droplets from the airstream, which are subsequently collected and stored for offline analysis. We report details of the design, operation, and modelled and measured probe performance.Computational fluid dynamics (CFD) was used to understand the flow patterns around the complex interior geometrical features that were optimized to ensure efficient droplet capture. CFD simulations coupled with particle tracking and multiphase surface transport modelling provide detailed estimates of the probe performance across the entire range of flight operating conditions and sampling scenarios.Physical operation of the probe was tested on a Lockheed C-130 Hercules (fuselage mounted) and de Havilland Twin Otter (wing pylon mounted) during three airborne field campaigns. During C-130 flights on the final field campaign, the probe reflected the most developed version of the design and a median cloud water collection rate of 4.5 mL min−1 was achieved. This allowed samples to be collected over 1–2 min under optimal cloud conditions. Flights on the Twin Otter featured an inter-comparison of the new probe with a slotted-rod collector, which has an extensive airborne campaign legacy. Comparison of trace species concentrations showed good agreement between collection techniques, with absolute concentrations of most major ions agreeing within 30 %, over a range of several orders of magnitude.

Glissonian approach combined with major hepatic vein first for laparoscopic anatomic hepatectomy

BackgroundLaparoscopic anatomic hepatectomy remains challenging because of the complex interior structures of the liver. Our novel strategy includes the Glissonian approach and the major hepatic vein first, which serves to define the external and internal landmarks for laparoscopic anatomic hepatectomy. MethodsEleven cases underwent laparoscopic anatomic hepatectomy, including three right hepatectomies, three left hepatectomies, three right posterior hepatectomies, and two mesohepatectomies. The Glissonian approach was used to transect the hepatic pedicles as external demarcation. The major hepatic vein near the hepatic portal was exposed and served as the internal landmark for parenchymal transection. The liver parenchyma below and above the major hepatic vein was transected along the major hepatic vein. Fifty-nine subjects were used to compare the distance between the major hepatic vein and secondary Glisson pedicles among different liver diseases. ResultsThe average operative time was 327 min with an estimated blood loss of 554.55 mL. Only two patients received three units of packed red blood cells. The others recovered normally and were discharged on postoperative day 7. The distance between right posterior Glissonian pedicle and right hepatic vein was shorter in the patients with cirrhosis than that without cirrhosis, and this distance was even shorter in patients with hepatocellular carcinoma. ConclusionThe Glissonian approach with the major hepatic vein first is easy and feasible for laparoscopic anatomic hepatectomy, especially in patients with hepatocellular carcinoma and cirrhosis.

3D radar wavefield tomography of comet interiors

Answering fundamental questions about the origin and evolution of small planetary bodies hinges on our ability to image their surface and interior structure in detail and at high resolution. The interior structure is not easily accessible without systematic imaging using, e.g., radar transmission and reflection data from multiple viewpoints, as in medical tomography. Radar tomography can be performed using methodology adapted from terrestrial exploration seismology. Our feasibility study primarily focuses on full wavefield methods that facilitate high quality imaging of small body interiors. We consider the case of a monostatic system (co-located transmitters and receivers) operated in various frequency bands between 5 and 15 MHz, from a spacecraft in slow polar orbit around a spinning comet nucleus. Using realistic numerical experiments, we demonstrate that wavefield techniques can generate high resolution tomograms of comets nuclei with arbitrary shape and complex interior properties.

Discrete Cu(i) complexes for azide-alkyne annulations of small molecules inside mammalian cells.

The archetype reaction of "click" chemistry, namely, the copper-promoted azide-alkyne cycloaddition (CuAAC), has found an impressive number of applications in biological chemistry. However, methods for promoting intermolecular annulations of exogenous, small azides and alkynes in the complex interior of mammalian cells, are essentially unknown. Herein we demonstrate that isolated, well-defined copper(i)-tris(triazolyl) complexes featuring designed ligands can readily enter mammalian cells and promote intracellular CuAAC annulations of small, freely diffusible molecules. In addition to simplifying protocols and avoiding the addition of "non-innocent" reductants, the use of these premade copper complexes leads to more efficient processes than with the alternative, in situ made copper species prepared from Cu(ii) sources, tris(triazole) ligands and sodium ascorbate. Under the reaction conditions, the well-defined copper complexes exhibit very good cell penetration properties, and do not present significant toxicities.

Particle size characterisation of metals powders for Additive Manufacturing using a microwave sensor

The production of high-value and high-quality metal parts with complex interior structures is enabled by the use of Additive Manufacturing (AM) techniques, which use metal powders with repeatable characteristics. Of these characteristics, particle size distribution is a key factor. This paper describes a particle size sensor based on a microwave cavity. It works on the principle that the magnetic permeability of metallic powders at microwave frequencies depends strongly on the particle size distribution of the powder owing to the classical skin effect. The sensor's capability is demonstrated by measurement of the permeability of a range of Ti6Al4V alloy powders with different particle size distributions. Permeability is shown to be congruent generally with the existing theory. The reduced imaginary permeability compared with the theoretical case observed for larger particle sizes is shown to be consistent with simulation. The method is also demonstrated to be highly precise, able to detect changes of <0.1μm for particles of average radii of approximately 11.7μm. Increases in sensitivity are possible by optimising the sensor design so that it operates in the regime where the permeability changes most rapidly as a function of particle size.

Large cosolutes, small cosolutes, and dihydrofolate reductase activity

Protein enzymes are the main catalysts in the crowded and complex cellular interior, but their activity is almost always studied in dilute buffered solutions. Studies that attempt to recreate the cellular interior in vitro often utilize synthetic polymers as crowding agents. Here, we report the effects of the synthetic polymer cosolutes Ficoll, dextran, and polyvinylpyrrolidone, and their respective monomers, sucrose, glucose, and 1-ethyl-2-pyrrolidone, on the activity of the 18-kDa monomeric enzyme, Escherichia coli dihydrofolate reductase. At low concentrations, reductase activity increases relative to buffer and monomers, suggesting a macromolecular effect. However, the effect decreases at higher concentrations, approaching, and, in some cases, falling below buffer values. We also assessed activity in terms of volume occupancy, viscosity, and the overlap concentration (where polymers form an interwoven mesh). The trends vary with polymer family, but changes in activity are within threefold of buffer values. We also compiled and analyzed results from previous studies and conclude that alterations of steady-state enzyme kinetics in solutions crowded with synthetic polymers are idiosyncratic with respect to the crowding agent and enzyme.

Seasonal habitat requirements of Lemon Dove (Aplopelia larvata) in coastal forest: camera-trap surveys of a reclusive species

The modification of natural habitats requires behavioural plasticity, which may be challenging for ‘specialist’ species. Quantifying habitat requirements and behavioural responses of specialists to landscape transformation is thus a priority for baseline data to inform conservation practices. Using camera-trap surveys of the forest-dependent Lemon Dove Aplopelia larvata in conjunction with detailed microhabitat-scale covariates, we assessed habitat use during two periods in the year: autumn–winter and spring–summer (which largely encompassed peak breeding). We used occupancy modelling of forest-structural covariates to produce models of the probability of occupancy and detection of Lemon Doves in patches of the Indian Ocean Coastal Belt Forest of South Africa. The average occupancy and detection probability as indicated by the top-performing models was 0.39 ± 0.08 and 0.26 ± 0.05, respectively, during autumn–winter, and 0.37 ± 0.08 and 0.25 ± 0.04, respectively, during spring–summer. Although occupancy and probability of detection remained relatively constant between seasons, there was seasonal variation in the influence of individual covariates for both measures. The overall trend of positive influences on Lemon Dove occupancy was that of complex and diverse habitat structures and high plant species richness. The specific covariates that influenced occupancy positively during spring–summer may reflect the ecological requirements for nestling provisioning for both dietary needs and an avoidance of potential disturbance. Thus, while Lemon Doves may be less habitat-specific during autumn–winter, conservation management plans for safeguarding the breeding success of the species are advised to ensure adequate protection of large forest patches with complex and diverse interior structures and minimal disturbance.

A study and application of high-resolution methods for reef reservoir identification

Reefs represent a special type of carbonate trap that plays a key role in the migration, accumulation, and formation of a reservoir. They have commonly been the targets of exploration and development. However, reefs have complex interior structures and easily grow as thin, interbedded geological frames with reef microfacies that include the cap, core, and base of the reef. Because of the inherent drawbacks of seismic signals, including their low frequencies and narrow bandwidths, it is difficult to accurately identify reef reservoirs. Fortunately, the seismic frequency, phase, energy, waveform and other dynamic and geometrical properties can be used to compensate for the energy, expand the frequency bandwidth, and decompose and reconstruct the wavelet to obtain high-resolution seismic data. These data can highlight certain seismic responses of reefs, including boundary reflections, dome-shaped reflections from the reef outline, strong reflections from the reef cap, reflections from the reef bottom, and onlap reflections from the reef flanks. Some impedance response regularities, such as the lower impedance of the reef cap relative to the reef core and biodetritus beach and the fluctuating impedance of the reef-flat complex, are observed by combining log data with geological and high-resolution seismic data for a reef reservoir inversion. These methods were applied to the Changxing Formation in the Yuanba Gas Field. Good prediction results were obtained with a high consistency between the log and seismic data in a comparative analysis with the original seismic data and well logs.

First assessment of MODIS satellite ocean color products (OC3 and nFLH) in the Inner Sea of Chiloe, northern Patagonia

The use of remote sensing has allowed enormous progress in our understanding of biophysical processes worldwide. Despite their importance, the use of satellite bio-optical products is still limited due to optical complexity. In this study we assess the performance of the Moderate Resolution Imaging Spectroradiometer algorithm for chlorophyll-a (MODIS-OC3) and of normalized Fluorescence Line Height (nFLH), in inner waters of northern Chilean Patagonia (41°-45oS). Satellite data were evaluated using a compilation of in situ chlorophyll-a data collected by the CIMAR-FIORDOS program during 2003-2012. During austral spring MODIS-OC3 showed a significant relationship with in situ measurements (R2 = 0.2, P = 0.03, F = 5.33) in comparison with winter when the relationship was non-significant. In contrast, nFLH explained a significant fraction of observed variance of Chl-a during austral winter (R2 = 0.54, P = <0.01, F = 10.68) and this relationship was not significant in spring. Our preliminary results offer an excellent chance to understand patterns of variability of the autotrophic biomass and physiological status in optically complex interior marine ecosystems.

Faster paleospin and deep-seated uncompensated mass as possible explanations for Ceres’ present-day shape and gravity

We show that Ceres’ measured degree-2 zonal gravity, J2, is smaller by about 10% than that derived assuming Ceres’ rotational flattening, as measured by Dawn, is hydrostatic. Irrespective of Ceres’ radial density variation, as long as its internal structure is hydrostatic the J2 predicted from the shape model is consistently larger than measured. As an explanation, we suggest that Ceres’ current shape may be a fossil remnant of faster rotation in the geologic past. We propose that up to ∼7% of Ceres’ previous spin angular momentum has been removed by dynamic perturbations such as a random walk due to impacts or a loss of satellite that slowed Ceres spin as it tidally evolved outward. As an alternative, we also consider a formal degree-2 admittance solution, from which we infer a range of possible non-hydrostatic contributions to J2 from uncompensated, deep-seated density anomalies. We show that such density anomalies could be due to low order convection or upwelling. The normalized moments-of-inertia derived for the two explanations – faster paleospin and deep-seated density anomalies – range between 0.353 ± 0.009 and 0.375 ± 0.001 for a spherically equivalent Ceres, which can be used as constraints on more complex Ceres interior models.

Seismic characterization of a carbonate reservoir in Tarim Basin

Seismic characterization of carbonate reservoirs is a challenging task for geophysicists because of their special depositional environment and complex interior structures. We developed a case study of the seismic characterization of a karstified carbonate reservoir in the Tarim Basin, western China. The characterization procedure is sequential and includes fault and fracture detection, seismic facies classification, seismic impedance inversion, and lithofacies classification. We presented a dip-steered coherence algorithm for detecting faults and karst fractures in the carbonate reservoir. Incorporating the dip information improves the performance and robustness. We applied normalized seismic segments, rather than the amplitude values, as the input to seismic facies classification, so as to reduce the impact of strong amplitudes, such as karst fractures, and to enable the analysis of weak amplitudes in the background strata. For the impedance inversion, we adopted a Fourier integral method for fast simulation in the stochastic inversion in this karstified carbonate reservoir. The algorithm honors the lateral variation based on the seismic trace similarity, instead of the lateral variogram that is commonly used in stochastic inversion. We conducted lithofacies classification, in which we used seismic coherence as a prior knowledge, so as to honor the fracture-associated local lithofacies with dolomitization and to distinguish it from limestone without dolomitization. Based on reservoir characterization described above, we determined three drilling wells for potential oil/gas exploration.

Multiparticle Brownian dynamics simulation of experimental kinetics of cytochrome bf oxidation and photosystem I reduction by plastocyanin

A model of electron transport from cytochrome f to photosystem I mediated by plastocyanin was designed on the basis of the multiparticle Brownian dynamics method. The model combines events which occur over a wide time range, including protein diffusion along the thylakoid membrane, long-distance interactions between proteins, formation of a multiprotein complex, electron transfer within a complex and complex dissociation. Results of the modeling were compared with the experimental kinetics measured in chloroplast thylakoids. Computer simulation demonstrated that the complex interior of the photosynthetic membrane, electrostatic interactions and Brownian diffusion provide physical conditions for the directed electron flow along the photosynthetic electron transport chain.

Laser sealing of organic light-emitting diode using low melting temperature glass frit

Glass frit encapsulation for laser-base sealing of the complex interiors results challenges for the electronics manufacturing process. The conventional frit packaging method relies on elevating thermal process by furnace where the package is heated to required temperature, hence limiting the use of temperature-sensitive materials and also creating problems in different packaging processes or multi-stage sealing products. In this paper, the benefits of combining novel laser-assist hermetical sealing and low temperature glass frit packaging are demonstrated and the technique offers a suitable and feasible solution. This frit of absorbent at specific laser wavelength is selected and applied as excellent contact with both large CTE range substrates. Glass frit composites consisting of a PbTiO3 ceramic and the rare earth Nd2O3 are evaluated for thermal properties and electrical characteristics. This developed glass frit hermetical sealing method achieves moisture durability, satisfying the enculturation of electronics-level. In this paper, we demonstrate successfully using laser to seal organic light emitting diode (OLED) via low melting temperature glass frit.

Iconography of the Virgin Mary in Medieval Wall Paintings in Ludrová–Kút in Slovakia

This paper analyses the role of the Virgin Mary in the largest Christological cycle in Slovakia (the medieval Upper Hungary). The All Saint´s Church is well-known thanks to complex interior medieva...

Alexander “Skunder” Boghossian

Alexander “Skunder” Boghossian Charles Henry Rowell Click for larger view View full resolution [End Page 7] In his interview with Lodie Robinson, Skunder offers us an important description of his work: In all my work, color is never a mere simulacrum of nature, but is used to illuminate, to create super imposed dimensions of form and shape, which in turn enables the viewer to first see the painting as a unit, then as a simultaneous breaking up of images, and finally as a recognition of the identities, for vision has no contour. Each viewer may thus see an endless number of images, according to his individual disposition; the images seen one day may have intermingled to form new images the next day, or even to have silently disappeared. One must mystically interpret my paintings, for they translate reality by using images of the non-real. And for this reason, in my best paintings, the figures seem to have emerged by themselves from the canvas, instead of having merely been placed there. Painting for me is not an artificial construction of relationships craftily imposed upon an exterior world. For me the meaning of my paintings is found in the expression of an inarticulated sound from within, a message for the viewer. Skunder’s comments about his art might be read as an ars poetica or an artist statement. Whatever the case, the comments he offers us are, however indirectly, a directionscore on reading art—especially that which originates from the complex interior geography of its creator. ________ Chika Okeke-Agulu concludes his engaging article “African Artists and the Pan African Imaginary” in Nka (33, fall 2013) with this seminal statement: To the extent that their individual responses are inscribed in their art, it is safe to say that for Africa’s artists, as for their African American counterparts past and present, Africa remains a site of powerful imaginaries, a historical place to which they are bound by ancestry, and an idea that elicits powerful aesthetic and symbolic action. (69) Earlier in the same article, Okeke-Agulu describes what might be considered as Skunder Boghossian’s third major development as a visual artist. Okeke-Agulu judiciously argues that . . . if Paris initiated Boghossian into the world of Négritude and latter-day Pan-Africanism, and if his return to Ethiopia and travels in Africa affirmed his intellectual alignment with African cultural and artistic mythopoeic traditions, his sojourn in the United States beginning from 1970, at the height of the Black Arts movement (BAM), made him utterly aware of the shared histories, politics, and cultures of continental Africans like him and their African American counterparts. Although he mostly avoided directly political themes in his pre-America paintings—most certainly because he was concerned earlier with affirmative meditations on the birth and promise of independent Africa—the radical [End Page 8] politics of Black Power and the BAM in the United States seems to have inspired paintings with coded and overt political themes, such as Black Emblem (1969), The End of the Beginning (1972), and DMZ (1975). Boghossian’s involvement with the BAM impacted his work in another way. Whereas his earlier paintings largely depended on the combination of biomorphic forms and minutely detailed abstract notations, he populated the space of his new work with bold, polychromatic, geometric, and more decisively “African” motifs. It seems to me that there is an obvious affinity between his new, BAM-period style and that of the members of the AfriCOBRA, whose work, as Jeff R. Donaldson noted in the group’s unofficial manifesto in 1970, aspired to “symmetry that is free, repetition with change, based on African music and African movement. The rhythm that is easy syncopation and very very human. Uncontracted. The rhythm the rhythm the rhythm rhythm rhythm.” (62) ________ Alexander “Skunder” Boghossian, a painter and educator, was born in 1937 to an Ethiopian mother and an Armenian father. A precocious youth, he was given a government scholarship, which allowed him to travel to London to study at the Slade School of Fine Art, and two years later to Paris, where he studied and taught at the Académie de la Grande Chaumière. In 1966...

Airport Emergency Evacuation Planning: An Agent-Based Simulation Study of Dirty Bomb Scenarios

Emergency evacuation from airports is an important consideration given the continuing occurrence of both natural and human caused disasters. Unfortunately, the traditional evacuation-drill approach to prepare for emergency situations presents several practical challenges at the scale and magnitude required for airports. In this paper, we present an agent-based model (ABM) called exitus which is capable of determining the extent to which collective behavior and overall evacuation time of passenger groups is affected by changes in the built environment for large, complex structures. The model is unique because it explicitly considers the physical and psychological characteristics of individuals with disabilities. In our first experiment, several bomb simulation scenarios were conducted at an international airport using exitus. Several important findings were revealed including: 1) the importance of stairway and exit configurations; 2) the inherent weaknesses of the pier airport design in affecting timely evacuations; 3) who the most vulnerable groups of people are; 4) the particular risk engendered from crowded or complex building interiors for individuals with disabilities; and 5) the potential problems caused by locating explosive detection system machines near passenger processing areas. The results of a second exploratory experiment also revealed the importance of realistically modeling psychological attributes of individuals with disabilities and their potential impact on collective evacuation performance. Overall the findings demonstrated the model’s ability to generate a common operational picture capable of guiding preparedness efforts for both public and private organizations encompassing a wide variety of professional endeavor.

Diffusion induced concave Co3O4@CoFe2O4 hollow heterostructures for high performance lithium ion battery anode

A facile and effective approach to prepare Co3O4/CoFe2O4 hollow cubes with uniform size and complex interior architectures is proposed via annealing of metal-cyanide-bridged hybrid coordination polymers (HCPs). The synergistic effect of the hybrid metal oxides and the rational design of the architecture endow these heterostructures with good lithium storage property and charge carrier transfer kinetics. In the hybrid materials, CoFe2O4 offers high theoretical capacity and Co3O4 provides stability at high current densities, leading to the significant enhancement in lithium storage properties comparing to the pure CoFe2O4. For example, Co3O4/CoFe2O4 heterostructures annealed at 800°C exhibit a high capacity of 511mAhg−1 at a current density of 8.0Ag−1 and a reversible capacity of 515mAhg−1 during the 500th cycle at a current density of 5.0Ag−1.