Primitive Surface Research Articles

Low-temperature reflectance spectra of brucite and the primitive surface of 1-Ceres?

The surface of Ceres, the most massive asteroid, presents a peculiar absorption band at 3.06μm. This feature has been attributed to a number of candidate phases, including a magnesium hydroxide, brucite (Mg(OH)2). In order to gain insights into this possibility we have investigated the evolution of brucite reflectance spectrum under decreasing temperature (down to 93K). Following early observation of brucite infrared spectra in transmission, a strong evolution of the reflectance spectrum of brucite is found under decreasing temperature. Small shifts of the band positions are found in particular at 1.36 and 1.39μm, while the most important evolution is a decrease in intensity of the features at 2.82 and 3.06μm. These observations can be seen in the light of the nature of these modes, which are transitions from excited states (difference bands) that are less populated under low-temperature. Such results provide a major test for the presence of brucite on Ceres from forthcoming DAWN observations, by searching for a possible evolution of the band with local time and then surface temperature. Based on the fact that the equivalent summation bands are not observed in Ceres spectra, brucite is not favored as the major constituent to the 3.06μm feature. The possibility that this feature rather corresponds to ammoniated minerals (phyllosilicates or salts) is discussed.

Forming mechanism of radial V-shaped microgrooves on plate using step punching method

The finned surface can increase the specific surface area, which could enhance the boiling efficiency of the working medium to realize the enhancement of heat transfer performance. This research adopted a step punching method to form a radial microgroove structure on the surface of a copper plate. The scanning electron microscopy analysis indicates that when the pressed metal is in the deformation range, it will flow under extrusion and is subject to the reaction force from the metal outside the deformation range, so a micro-finned structure nearby the punching tool is formed. And the deformation area of the formed microgroove is higher than the workpiece’s primitive surface. The relationships of the punching interference length Li with θc, ac, and αpt are analyzed; and the influence of forming parameters on the groove surface morphology as well as the relationships among these parameters are discussed. When the punching depth ac is 0.3 mm and the punching feeding angle θc is 2°–4°, the finned surface of the radial V-shaped microgrooves can be obtained.

Shape recognition of CAD models via iterative slippage analysis

A new slippage analysis method for recognizing basic primitive surfaces of CAD models is presented in this paper. Obtaining the exact normal and searching the appropriate local region of each point are found to be the key steps for determining the local slippage motion type. First, the tensor voting-based boundary point recognition method is integrated to preprocess the original points. Then, the local slippage analysis method is used to initialize the point type. Furthermore, the appropriate region of each point is acquired by the region growing method. Meanwhile, the middle level information (the basic primitive surface types and the representative parameters) is found, guiding the modification of the normal of each point and the iterative detection of the surface types. Finally, the middle level information-based smooth method is introduced to refine the boundary of each basic primitive surface. The empirical results show that the proposed algorithm is efficient and robust for recognizing primitive shapes from CAD models of mechanical parts.

Ion irradiation of Allende meteorite probed by visible, IR, and Raman spectroscopies

Little is known about carbonaceous asteroids weathering in space as previous studies have struggled to define a general spectral trend among dark surfaces. Here we present experiments on ion irradiation of the Allende meteorite, performed using 40keV He+ and Ar+ ions, as a simulation of solar wind irradiation of primitive bodies surfaces. We used different fluences up to 3×1016ions/cm2, corresponding to short timescales of ∼103–104yrs in the main asteroid belt. Samples were analyzed before and after irradiation using visible to far-IR (0.4–50μm) reflectance spectroscopy, and Raman micro-spectroscopy. Similarly to what observed in previous experiments, results show a reddening and darkening of VIS–NIR reflectance spectra. These spectral variations are however comparable to other spectral variations due to viewing geometry, grain size, and sample preparation, suggesting an explanation for the contradictory space weathering studies of dark asteroids. After irradiation, the infrared bands of the matrix olivine silicates change profile and shift to longer wavelength, possibly as a consequence of a more efficient sputtering effect on Mg than Fe (lighter and more volatile species are preferentially sputtered backwards) and/or preferential amorphization of Mg-rich olivine. Spectral variations are compatible with the Hapke weathering model. Raman spectroscopy shows that the carbonaceous component is substantially affected by irradiation: different degrees of de-ordering are produced as a function of dose, to finally end with a highly disordered carbon. All observed modifications seem to scale with the nuclear elastic dose.

Human embryonic epidermis contains a diverse Langerhans cell precursor pool

Despite intense efforts, the exact phenotype of the epidermal Langerhans cell (LC) precursors during human ontogeny has not been determined yet. These elusive precursors are believed to migrate into the embryonic skin and to express primitive surface markers, including CD36, but not typical LC markers such as CD1a, CD1c and CD207. The aim of this study was to further characterize the phenotype of LC precursors in human embryonic epidermis and to compare it with that of LCs in healthy adult skin. We found that epidermal leukocytes in first trimester human skin are negative for CD34 and heterogeneous with regard to the expression of CD1c, CD14 and CD36, thus contrasting the phenotypic uniformity of epidermal LCs in adult skin. These data indicate that LC precursors colonize the developing epidermis in an undifferentiated state, where they acquire the definitive LC marker profile with time. Using a human three-dimensional full-thickness skin model to mimic in vivo LC development, we found that FACS-sorted, CD207(-) cord blood-derived haematopoietic precursor cells resembling foetal LC precursors but not CD14(+)CD16(-) blood monocytes integrate into skin equivalents, and without additional exogenous cytokines give rise to cells that morphologically and phenotypically resemble LCs. Overall, it appears that CD14(-) haematopoietic precursors possess a much higher differentiation potential than CD14(+) precursor cells.

大規模点群からの生産設備の形状再構成 (第1報)

The recent progress of laser scanners makes it possible to capture dense point-clouds of large-scale facilities. Large-scale facilities are mainly composed of many primitive surfaces, such as planes, cylinders, cones, spheres, and tori. However, it is not easy to reliably extract these surfaces from point-clouds because it is actually difficult to capture complete point-clouds of surfaces. In this paper, we discuss how to reconstruct pipe structures from insufficiently extracted surfaces. In our method, we first extract planes and cylinders, which can be reliably extracted, and detect the relationship among detected surfaces on a depth image. Then we estimate shapes and locations of various pipe structures using the relationships among surfaces. Finally we verify estimated shapes based on visibility tests and eliminate inconsistent structures. In our experiments, our method could sufficiently reconstruct pipe structures using only a single scanning data.

A New Parameterised Feature-Based Generic 3D Human Face Model for Emotional Bio-Robots

To represent various human facial expressions is an essential requirement for emotional bio-robots. The human expressions can convey certain emotions for communications of human beings with some muscles positions and their movements. To design and develop emotional robots, it is necessary to build a generic 3D human face model. While the geometrical features of human faces are freeform surfaces with complex properties, it is the fundamental requirement for the model to have the ability of representing both primitive and freeform surfaces. This requirement makes the Non-rational Uniform B-Spline (NURBS) are suitable for 3D human face modelling. In this paper, a new parameterised feature based generic 3D human face model is proposed and implemented. Based on observation of human face anatomy, the authors define thirty-four NURBS curve features and twenty-one NURBS surface features to represent the human facial components, such as eyebrows, eyes, nose and mouth etc. These curve models and surface models can be used to simulate different facial expressions by manipulating the control points of those NURBS features. Unlike the existing individual based face modelling methods, this parameterised 3D face model also gives users the ability to use the model imitate any face appearances. In addition the potential applications of the new proposed 3D face model are also discussed. Besides emotional bio-robots, it is believed that the proposed model can also be applied in other fields such as aesthetic plastic surgery simulation, film and computer game characters creation, and criminal investigation and prevention.

Periodic entanglement II: weavings from hyperbolic line patterns

Ordered arrays of cylinders, known as rod packings, are now widely used in descriptions of crystalline structures. These are generalized to include crystallographic packed arrays of filaments with circular cross sections, including curvilinear cylinders whose central axes are generic helices. A suite of the simplest such general rod packings is constructed by projecting line patterns in the hyperbolic plane ({\bb H}^2) onto cubic genus-3 triply periodic minimal surfaces in Euclidean space ({\bb E}^3): the primitive, diamond and gyroid surfaces. The simplest designs correspond to `classical' rod packings containing conventional cylindrical filaments. More complex packings contain three-dimensional arrays of mutually entangled filaments that can be infinitely extended or finite loops forming three-dimensional weavings. The concept of a canonical `ideal' embedding of these weavings is introduced, generalized from that of knot embeddings and found algorithmically by tightening the weaving to minimize the filament length to volume ratio. The tightening algorithm builds on the SONO algorithm for finding ideal conformations of knots. Three distinct classes of weavings are described.

A hybrid defect detection for in-tray semiconductor chip

The requirements for high-speed and high-precision defect inspection in semiconductor chip are growing rapidly because of the complicated surface in semiconductor chip. Due to manufacturing tolerance of IC tray, the misalignment from the chip positioning shift and rotation are always presented for the application of in-tray inspection. In the beginning, this paper focuses on compensating the positioning shift and rotation of in-tray chip by using the proposed image alignment algorithm before the defect detection. After applying the process of image alignment, a hybrid approach of defect detection is applied to detect the defects of in-tray chip. Furthermore, this hybrid approach simultaneously detects the defects based on its surface by the following two categories: (1) the complicated surface in the circuit and (2) the primitive surface on the bump. As mentioned above, the image alignment strategy and the adaptive image difference method are applied in the detection of complicated surface, and the design-rule strategy is adapted to detect the defects on bumps. Finally, the experimental results show that the proposed image alignment strategy and hybrid approach can accurately and rapidly inspect the defects of in-tray chip. This approach is superior to the traditional template matching in defect detection. In addition, the computational complexity can be efficiently reduced by the proposed hybrid strategy.

Finite Element Analysis of Schwarz P Surface Pore Geometries for Tissue‐Engineered Scaffolds

Tissue engineering scaffolds provide temporary mechanical support for tissue regeneration. To regenerate tissues more efficiently, an ideal structure of scaffolds should have appropriate porosity and pore structure. In this paper, we generate the Schwarz primitive (P) surface with various volume fractions using a phase‐field model. The phase‐field model enables us to design various surface‐to‐volume ratio structures with high porosity and mechanical properties. Comparing the Schwarz P surface′s von Mises stress with that of triply periodic cylinders and cubes, we draw conclusions about the mechanical properties of the Schwarz P surface.

Generation of induced Pluripotent Stem Cells from Human Amnion Epithelium

Generation of induced Pluripotent Stem Cells from Human Amnion Epithelium

On universal Severi varieties of low genus K3 surfaces

We prove the irreducibility of universal Severi varieties parametrizing irreducible, reduced, nodal hyperplane sections of primitive K3 surfaces of genus g, with 3 ≤ g≤11, g ≠ 10.

Cartesian oval representation of freeform optics in illumination systems

The geometrical method for constructing optical surfaces for illumination purpose developed by Oliker and co-workers [Trends in Nonlinear Analysis (Springer, 2003)] is generalized in order to obtain freeform designs in arbitrary optical systems. The freeform is created by a set of primitive surface elements, which are generalized Cartesian ovals adapted to the given optical system. Those primitives are determined by Hamiltonian theory of ray optics. The potential of this approach is demonstrated by some examples, e.g., freeform lenses with collimating front elements.

Synergistic effects of growth factors and mesenchymal stromal cells for expansion of hematopoietic stem and progenitor cells

The number of hematopoietic stem and progenitor cells (HPCs) per cord blood unit is limited, and this can result in delayed engraftment or graft failure. In vitro expansion of HPCs provides a perspective to overcome these limitations. Cytokines as well as mesenchymal stromal cells (MSCs) have been shown to support HPCs ex vivo expansion, but a systematic analysis of their interplay remains elusive. Twenty different combinations of growth factors (stem cell factor [SCF], thrombopoietin [TPO], fibroblast growth factor-1 [FGF-1], angiopoietin-like 5, and insulin-like growth factor-binding protein 2), either with or without MSC coculture were systematically compared for their ability to support HPC expansion. CD34(+) cells were stained with carboxyfluorescein diacetate N-succinimidyl ester to monitor cell division history in conjunction with immunophenotype. Colony-forming unit frequencies and hematopoietic reconstitution of nonobese diabetic severe combined immunodeficient mice were also assessed. Proliferation of HPCs was stimulated by coculture with MSCs. This was further enhanced in combination with SCF, TPO, and FGF-1. Moreover, these conditions maintained expression of primitive surface markers for more than four cell divisions. Colony-forming unit-initiating cells were not expanded without stromal support, whereas an eightfold increase was reached by simultaneous cytokine-treatment and MSC coculture. Importantly, in comparison to expansion without stromal support, coculture with MSCs significantly enhanced hematopoietic chimerism in a murine transplantation model. The supportive effect of MSCs on hematopoiesis can be significantly increased by addition of specific recombinant growth factors; especially in combination with SCF, TPO, and FGF-1.

A geometric criterion for the nonuniform hyperbolicity of the Kontsevich--Zorich cocycle

We establish a geometric criterion on a $SL(2, R)$-invariant ergodic probability measure on the moduli space of holomorphic abelian differentials on Riemann surfaces for the nonuniform hyperbolicity of the Kontsevich--Zorich cocycle on the real Hodge bundle. Applications include measures supported on the $SL(2, R)$-orbits of all algebraically primitive Veech surfaces (see also [7]) and of all Prym eigenforms discovered in [34], as well as all canonical absolutely continuous measures on connected components of strata of the moduli space of abelian differentials (see also [4, 17]). The argument simplifies and generalizes our proof for the case of canonical measures [17]. In the Appendix, Carlos Matheus discusses several relevant examples which further illustrate the power and the limitations of our criterion.

Rationale and techniques of cytoreductive surgery and peritoneal chemohyperthermia

The evolution of loco-regional treatments has occurred in the last two decades and has deeply changed the natural history of primitive and secondary peritoneal surface malignancies. Several phase II-III studies have proved the effectiveness of the combination of cytoreductive surgery with peritoneal chemohyperthermia. Cytoreductive surgery allows the reduction of the neoplastic mass and increases tumoral chemosensitivity. The development of chemohyperthermia finds its origins in the necessity to exceed the limits of intraperitoneal chemotherapy performed in normothermia. It permits a continuous high concentration gradient of chemotherapeutic drugs between the peritoneal cavity and the plasma compartment to and a more uniform distribution throughout the abdominal cavity compared to systemic administration.

Isolation and Functional Characterization of a Novel “Oxidative State – low” Leukemic Population with Stem Cell Properties and Potential Resistance to Chemotherapy In Acute Myeloid Leukemia.

AbstractAbstract 1580Most adults with acute myeloid leukemia (AML) are not cured with current treatments due to primary chemo-resistance or relapse. Emerging evidence suggests that the pool of leukemic blasts is heterogeneous and disease persistence is due to a subset of leukemic (-stem) cells able to evade chemotherapy and sustain tumor growth. Cell surface marker expression has proven to be a valuable tool to isolate and study leukemic stem cells (LSC) which, similarly to normal hematopoiesis, are shown to reside in the CD34+/CD38- leukemic fraction. However, recent data indicate that the phenotype of LSC varies from patient to patient and it seems likely that no single phenotypic signature exists to uniformly identify LSC. Besides immunophenotype, isolating LSC on the basis of functional properties unique for these cells may enforce our understanding of AML biology and provide the basis to develop more effective therapies. Reactive oxygen species (ROS) regulate essential cellular functions such as self-renewal, proliferation and apoptosis. In normal neurogenesis and hematopoiesis, ROSlow states correlate with self-renewal and ROShigh is associated with differentiation. In malignant tissues, although cancer cells are commonly more oxidized than their normal counterparts, some cancer stem cells are shown to contain low ROS levels, a feature associated with increased resistance to therapy (Nature. 2009;458:780-783). We hypothesized that LSCs also reside in a less oxidized state than bulk leukemic cells, a condition which promotes self-renewal and confers resistance to chemotherapy. To validate this hypothesis, we evaluated the redox state of leukemic blasts isolated from bone marrow or peripheral blood from 21 AML and 2 high-risk MDS patients. Loading of cells with the fluorescent probe DCF-DA showed that primary AML specimens have a broad range of oxidative state, with cells clearly falling into ROShigh and ROSlow populations (ROSlow=11.5±9%). Phenotypic analyses of AML specimens with respect to primitive cell surface markers indicated that the ROSlow gate represented 18 ± 17% of the phenotypically primitive CD34+/CD38- cells and was significantly more enriched in CD34-/CD38- leukemic cells in comparison to ROShigh. We isolated ROSlow and ROShigh leukemic subsets by flow cytometric sorting on the basis of their DCF fluorescence from 11 AML patients' samples and analyzed them for stem cell properties and drug sensitivity. Importantly, we used the differential redox state and not phenotypic markers to isolate distinct leukemic subpopulations. Morphological evaluation of sorted CD45/SS blast gated, DCFlow and DCFhigh cells demonstrated that both subpopulations were leukemic. Comparative analysis of the cell cycle distribution after staining with Ki67 and 7AAD indicated in most cases that ROSlow cells are quiescent, in contrast to ROShigh and total blast cells which are more actively cycling. Despite their predominant quiescent state, ROSlow leukemic cells were able both to grow as colonies in CFU assays and also to engraft in NOD SCID mice in pilot experiments, suggesting the existence of both leukemic “progenitor” and “stem” cell types within the ROSlow leukemic fraction. Based on these data, we challenged primary AML specimens with conventional chemotherapy agents (daunorubicin and AraC). Intriguingly, ROSlow cells preferentially survived exposure to either antileukemic agent in vitro. Taken together, our data identify a novel quiescent “oxidative state – low” leukemic population from patients with AML/MDS at diagnosis, which displays stem cell properties and exhibits functional differences related to drug sensitivity. The detailed molecular and functional characterization of this novel leukemic population is the subject of our ongoing studies. Disclosures:No relevant conflicts of interest to declare.

A phase-field approach for minimizing the area of triply periodic surfaces with volume constraint

In this paper, we present an accurate and efficient algorithm to generate constant mean curvature surfaces with volume constraint using a phase-field model. We implement our proposed algorithm using an unconditionally gradient stable nonlinear splitting scheme. Starting from the periodic nodal surface approximation to minimal surfaces, we can generate various constant mean curvature surfaces with given volume fractions. We generate and study the Schwarz primitive (P), Schwarz diamond (D), and Schoen gyroid (G) surfaces with various volume fractions. This technique for generating constant mean curvature surfaces can be used to design biomedical scaffolds with optimal mechanical and biomorphic properties.

Geochemistry of magmatic rocks and time constraints on deformational phases and shear zone slip in the Méiganga area, central Cameroon

The Méiganga area is situated in the Adamawa–Yadé domain (AYD) of the Pan-African fold belt in Cameroon. The AYD is characterized by abundant plutonic rocks that intruded Palaeoproterozoic gneisses. It is cut by the transcurrent Central Cameroonian Shear Zone (CCSZ). The studied area is made up of metadiorite (MD), pyroxene-bearing granite (PGr) and biotite-muscovite granite (BMGr), hosted in a metasedimentary sequence of amphibole-biotite gneisses. The granitoids are metaluminous to slightly peraluminous, and mainly of I-type (ASI ≤ 1.1), representing a high-K calc-alkaline to shoshonitic suite. They were derived from crustal protoliths (BMGr), from rocks of mantle origin (MD, PGr), and/or from the remelting of metabasalt or metatonalite (MD, PGr). Four successive deformational phases (D1, D2, D3, and D4) are present in the Méiganga area. The S1 foliation is formed by tectonic transposition of the S0 primitive surface represented by contacts between the gneiss and intercalated amphibolites. The synmigmatitic D2 deformational phase is characterized by S2 banded schistosity, S2/C2 sinistral shear planes, and F2 folds with axes parallel to a L2 stretching lineation. Imprints of the D2 and subsequent deformational phases are similar in the metadiorite and host rocks, implying syn-D2 emplacement and crystallization of the metadiorite; therefore 614–619 Ma 207Pb/206Pb zircon evaporation ages obtained for this rock type date the syn-D2 magmagenesis. Similarly, the D3 phase of the PGr is 601 ± 1 Ma, dated by the 207Pb/206Pb evaporation method. D4 is a late-stage brittle deformational phase. Sinistral movement of the CCSZ is associated with D2, whereas its latest activity, characterized by dextral slip, cannot be older than emplacement of the 558 ± 2 Ma BMGr (207Pb/206Pb zircon evaporation age).

Three-dimensional Euclidean nets from two-dimensional hyperbolic tilings: kaleidoscopic examples

We present a method for geometric construction of periodic three-dimensional Euclidean nets by projecting two-dimensional hyperbolic tilings onto a family of triply periodic minimal surfaces (TPMSs). Our techniques extend the combinatorial tiling theory of Dress, Huson & Delgado-Friedrichs to enumerate simple reticulations of these TPMSs. We include a taxonomy of all networks arising from kaleidoscopic hyperbolic tilings with up to two distinct tile types (and their duals, with two distinct vertices), mapped to three related TPMSs, namely Schwarz's primitive (P) and diamond (D) surfaces, and Schoen's gyroid (G).