Discontinuous Areas Research Articles

Regionalization of geographical space according to selected topographic factors in reference to spatial distribution of precipitation: application of artificial neural networks in GIS

In this paper, the regionalization of geographical space according to selected topographic factors and the spatial distribution of precipitation is discussed. The model takes into account qualitative and quantitative data describing the conditions associated with the studied precipitation. In the modelling, data mining methods including data clustering methods for agglomeration and artificial neural networks for classification have been used. The reason for their use was the classification of the area due to conditions related to precipitation, the distinguishing of similar areas and the delimitation of the propagation of the phenomenon or transition zones. To realize the research aims, professional software for data management, spatial data analysis, mathematical calculations and data mining have been used. The result of the research was a model of the classes representing areas with specific conditions affecting the phenomenon, transition zones between classes and areas with conditions other than those in the surroundings of the measuring stations, which are not classified in any of the classes. Classification results indicate the boundaries of the areas in which we can model the values measured at stations, the transition zones of possible discontinuous change and areas in which the phenomenon should not be modelled due to significantly different conditions from those in the neighbourhoods of measuring stations. Unclassified areas are also potential locations for new measuring stations.

A Miniature Binocular Endoscope with Local Feature Matching and Stereo Matching for 3D Measurement and 3D Reconstruction.

As the traditional single camera endoscope can only provide clear images without 3D measurement and 3D reconstruction, a miniature binocular endoscope based on the principle of binocular stereoscopic vision to implement 3D measurement and 3D reconstruction in tight and restricted spaces is presented. In order to realize the exact matching of points of interest in the left and right images, a novel construction method of the weighted orthogonal-symmetric local binary pattern (WOS-LBP) descriptor is presented. Then a stereo matching algorithm based on Gaussian-weighted AD-Census transform and improved cross-based adaptive regions is studied to realize 3D reconstruction for real scenes. In the algorithm, we adjust determination criterions of adaptive regions for edge and discontinuous areas in particular and as well extract mismatched pixels caused by occlusion through image entropy and region-growing algorithm. This paper develops a binocular endoscope with an external diameter of 3.17 mm and the above algorithms are applied in it. The endoscope contains two CMOS cameras and four fiber optics for illumination. Three conclusions are drawn from experiments: (1) the proposed descriptor has good rotation invariance, distinctiveness and robustness to light change as well as noises; (2) the proposed stereo matching algorithm has a mean relative error of 8.48% for Middlebury standard pairs of images and compared with several classical stereo matching algorithms, our algorithm performs better in edge and discontinuous areas; (3) the mean relative error of length measurement is 3.22%, and the endoscope can be utilized to measure and reconstruct real scenes effectively.

Least-squares horizons with local slopes and multigrid correlations

Most seismic horizon extraction methods are based on seismic local reflection slopes that locally follow seismic structural features. However, these methods often fail to correctly track horizons across discontinuities such as faults and noise because the local slopes can only correctly follow laterally continuous reflections. In addition, seismic amplitude or phase information is not used in these methods to compute horizons that follow a consistent phase (e.g., peaks or troughs). To solve these problems, we have developed a novel method to compute horizons that globally fit the local slopes and multigrid correlations of seismic traces. In this method, we first estimate local reflection slopes by using structure tensors and compute laterally multigrid slopes by using dynamic time warping (DTW) to correlate seismic traces within multiple laterally coarse grids. These coarse-grid slopes can correctly correlate reflections that may be significantly dislocated by faults or other discontinuous structures. Then, we compute a horizon by fitting, in the least-squares sense, the slopes of the horizon with the local reflection slopes and multigrid slopes or correlations computed by DTW. In this least-squares system, the local slopes on the fine grid and the multiple coarse-grid slopes will fit a consistent horizon in areas without lateral discontinuities. Across laterally discontinuous areas where the local slopes fail to correctly correlate reflections and mislead the horizon extraction, the coarse-grid slopes will help to find the corresponding reflections and correct the horizon extraction. In addition, the multigrid correlations or slopes computed by dynamic warping can also assist in computing phase-consistent horizons. We apply the proposed horizon extraction method to multiple 2D and 3D examples and obtain accurate horizons that follow consistent phases and correctly track reflections across faults.

Change Detection Algorithm Based on Discrete Wavelet Transforms and Neighborhood Fuzzy C-Means

A new algorithm on Discrete Wavelet Transform (DWT) and neighborhood FCM is proposed to detect change area from remote sensing image. First, the subtraction and ratio image are obtained by the subtraction and ratio method from the two registered remote sensing images; Then, the DWT is applied to the subtraction and ratio image, the region intensity-based and energy-based fusion rules is adopted to the low frequency and high frequency wavelet coefficients, and the inverse DWT is used to obtain the final difference image; At last, the neighborhood FCM is carried out to get the change areas, the spatial distance information and gray difference information are considered in the objective function of FCM, which could avoid misclassification and enhance the detection probability. Experimental results show that the proposed algorithm has strong ability to suppress noise and good detection results; the detection probability of unban change area can reach to 98.45%, whereas, the detection probability is up to 87.5% for the discontinuous forest change area.

Study on thermal effects of InSb infrared focal plane arrays irradiated by pulsed laser

To learn thermal effects of InSb infrared focal plane arrays (IRFPAs) detector irradiated by pulsed laser, basing on ANSYS software, and considering temperature dependent thermal parameters of InSb, a three dimensional temperature field analysis model of InSb IRFPAs detector by 1064 nm Gauss laser irradiation is built. The characteristics of temperature rise and temperature distribution in InSb IRFPAs detector are studied. The results show that the maximum temperature always occurs in InSb chip, locating at the top layer of InSb IRFPAs detector, the temperature rises in each layer are different, and the temperature distribution in InSb IRFPAs detector is quite different from that in single-layer material. The temperature distribution of InSb chip in InSb IRFPAs reduces from center to outside, while it shows not a smooth decrease, but a concentric-ringed ripple decrease with non-consecutive high temperature extremum regions. The temperature distribution patterns in underfill, Si readout integrated circuits are similar to that in InSb chip, but the discontinuous high temperature areas in InSb chip, underfill locate at the regions between indium bumps, and the discontinuous high temperature areas in Si readout integrated circuits locate at the contact area with indium bumps. This different temperature distribution phenomenon in each material is mainly due to its multi-layer architecture and quite different thermal properties of the middle layer, which is an interlacing layout of underfill and indium bumps. Besides, the influences of indium bump structure size on the temperature rise are also discussed. All these results qualitatively reflect the disciplines of temperature rise in InSb IRFPAs detector, providing a theory support for thermal analysis of detectors irradiated by laser.

Effects of microstrip line fabrication and design on high-speed signal integrity transmission of PCB manufacturing process

PurposeAs a common transmission line, the microstrip line plays an important role in high-speed circuits. The purpose of this paper was to investigate the effects of the circuit design of microstrip lines on the signal integrity (SI). In addition, the influence of the type and thickness of the solder resist ink on SI was analyzed to provide guidance for the related producing process design of printed circuit boards (PCBs).Design/methodology/approachMicrostrip line properties consisting of shape, line-width/line-space ratio, reference layer design and as-covered solder resist ink were designed to measure the insertion loss (S21) in high-speed PCB.FindingsThe study showed that the insertion loss (S21) of straight, meander, snake-shaped and wavy microstrip lines was approximately consistent. A microstrip line with width/space ratio less than 0.96 is necessary, as the differential line closing produces a mutual interference. Reference layer including the discontinuous area should be repaired by adjusting the microstrip line parameters. With regard to the solder resist ink, the insertion loss of novel solder resist ink decreased by 0.163 dB/in at 12.9 GHz and 0.164 dB/in at 14 GHz, compared with traditional solder resist ink. Accordingly, the insertion loss effectively improved at a lower thickness of solder resist.Originality/valueThis paper demonstrated that the common designing factors of line shape, line/space ratio, reference layer and solder resist influence microstrip line SI in the significant reference of designer-making PCB layout.

Planarity constrained multi-view depth map reconstruction for urban scenes

Multi-view depth map reconstruction is regarded as a suitable approach for 3D generation of large-scale scenes due to its flexibility and scalability. However, there are challenges when this technique is applied to urban scenes where apparent man-made regular shapes may present. To address this need, this paper proposes a planarity constrained multi-view depth (PMVD) map reconstruction method. Starting with image segmentation and feature matching for each input image, the main procedure is iterative optimization under the constraints of planar geometry and smoothness. A set of candidate local planes are first generated by an extended PatchMatch method. The image matching costs are then computed and aggregated by an adaptive-manifold filter (AMF), whereby the smoothness constraint is applied to adjacent pixels through belief propagation. Finally, multiple criteria are used to eliminate image matching outliers. (Vertical) aerial images, oblique (aerial) images and ground images are used for qualitative and quantitative evaluations. The experiments demonstrated that the PMVD outperforms the popular multi-view depth map reconstruction with an accuracy two times better for the aerial datasets and achieves an outcome comparable to the state-of-the-art for ground images. As expected, PMVD is able to preserve the planarity for piecewise flat structures in urban scenes and restore the edges in depth discontinuous areas.

A precursive study of the time-domain survey of the Galactic Anti-center using the Nanshan 1-meter telescope with variable stars detected

Following the LAMOST Spectroscopic Survey and the Xuyi’s Photometric Survey of the Galactic Anti-center, we plan to carry out a time-domain survey of the Galactic Anti-center (TDS-GAC) to study variable stars by using the Nanshan 1-meter telescope. Before the beginning of TDS-GAC, a precursive sky survey (PSS) has been executed. The goal of the PSS is to optimize the observation strategy of TDS-GAC and to detect some strong transient events, as well as to find some short time-scale variable stars of different types. By observing a discontinuous sky area of \(15.03~\mbox{deg}^{2}\) with the standard Johnson-Cousin-Bessel \(V\) filter, 48 variable stars are found and the time series are analyzed. Based on the behaviors of the light curves, 28 eclipsing binary stars, 10 RR Lyraes, 3 periodic pulsating variables of other types have been classified. The rest 7 variables stay unclassified with deficient data. In addition, the observation strategy of TD-GAC is described, and the pipeline of data reduction is tested.

ADHESIVE FORCE OF FLAT INDENTERS WITH BRUSH-STRUCTURE

We have numerically studied adhesive contact between a flat indenter with brush structure and an elastic half space using the boundary element method. Various surface structures with different size, number and shape of the “pillars”, as well as their distributions (regular or random) have been investigated. The results validate the theoretical prediction that the adhesive force in contact of an indenter with discontinuous areas is roughly proportional to the square root of the real contact density (“filling factor”).

A NEW HISTORY OF COMMUNITY FORMATION AND CHANGE AT KOLOMOKI (9ER1)

We present a revised chronology for the Kolomoki site (9ER1) in Georgia, occupied primarily during the Middle and Late Woodland periods (ca. 200 BC to AD 1050). The considerable extent of the site has been noted for more than a century but came into sharper focus with the archaeological investigations by Sears (1956) and Pluckhahn (2003). The site includes at least nine mounds, a large central plaza, and a discontinuous habitation area nearly a kilometer in diameter. Previous interpretations assumed gradual and incremental changes in the community plan. We present a greatly revised chronology, based on new investigations in some of the lesser-known portions of the site and a doubling of the number of absolute dates. Bayesian modeling of these and previous dates reveals that, far from the gradualist assumption of previous work, the community at Kolomoki was dynamically transformed several times in its history, reaching its greatest spatial extent and formal complexity in two relatively short-lived phases. In these intervals, the village incorporated permanent residents and visitors into a single community in which daily face-to-face interactions were minimized even as communal identity was celebrated.

Characterizing permafrost active layer dynamics and sensitivity to landscape spatial heterogeneity in Alaska.

An important feature of the Arctic is large spatial heterogeneity in active layer conditions, which is generally poorly represented by global models and can lead to large uncertainties in predicting regional ecosystem responses and climate feedbacks. In this study, we developed a spatially integrated modelling and analysis framework combining field observations, local scale (~ 50 m resolution) active layer thickness (ALT) and soil moisture maps derived from airborne low frequency (L+P-band) radar measurements, and global satellite environmental observations to investigate the ALT sensitivity to recent climate trends and landscape heterogeneity in Alaska. Modelled ALT results show good correspondence with in situ measurements in higher permafrost probability (PP ≥ 70%) areas (n = 33, R = 0.60, mean bias = 1.58 cm, RMSE = 20.32 cm), but with larger uncertainty in sporadic and discontinuous permafrost areas. The model results also reveal widespread ALT deepening since 2001, with smaller ALT increases in northern Alaska (mean trend = 0.32 ± 1.18 cm yr-1) and much larger increases (> 3 cm yr-1) across interior and southern Alaska. The positive ALT trend coincides with regional warming and a longer snow-free season (R = 0.60 ± 0.32). A spatially integrated analysis of the radar retrievals and model sensitivity simulations demonstrated that uncertainty in the spatial and vertical distribution of soil organic carbon (SOC) was the largest factor affecting modeled ALT accuracy, while soil moisture played a secondary role. Potential improvements in characterizing SOC heterogeneity, including better spatial sampling of soil conditions and advances in remote sensing of SOC and soil moisture, will enable more accurate predictions of active layer conditions and refinement of the modelling framework across a larger domain.

Population genetic structure of the intertidal kinorhynchEchinoderes marthae(Kinorhyncha; Cyclorhagida; Echinoderidae) across the São Sebastião Channel, Brazil

Abstract Barriers to gene flow in marine environments vary between species and are highly dependent on dispersal ability and habitat discontinuity. Intertidal sand and mud flats are discontinuous areas, separated by other habitat types along a coastline or by subtidal zones. The Sao Sebastiao Channel in eastern Brazil, which is situated between Rio de Janeiro and Sao Paulo, harbors two intertidal mud flats where populations of the kinorhynch Echinoderes marthae are found, one on the mainland (Araca Bay) and one on Sao Sebastiao Island (Ilhabela). Here, we investigated the genetic structure of two E. marthae populations across the Sao Sebastiao Channel, in order to contribute to the ongoing debate on biogeography of meiobenthic animals. Based on 628 bp of the mitochondrial CO1 gene, we find that E. marthae shows low levels of structure in the Sao Sebastiao Channel (FST = 0.165), and find evidence of recent demographic expansion across populations.

Research on Depth Estimation Method of Light Field Imaging Based on Big Data in Internet of Things From Camera Array

In recent years, optical field imaging technology has received extensive attention in the academic circle for its novel imaging characteristics of shooting first and focusing later, variable depth of field, variable viewpoint, and so on. However, the existing optical field acquisition equipment can only acquire a limited number of discrete angle signals, so image aliasing caused by under sampling of optical field angle signals reduces the quality of optical field images. Based on the camera array system as a platform, this paper studies the optical field imaging and depth estimation method based on the Big Data in Internet of Things obtained from camera array around the angle sampling characteristics of the optical field data set, and has achieved some innovative research results in the following aspects. On the basis of analyzing the characteristics of different depth clues in the optical field data set, a depth estimation method combining parallax method and focusing method is proposed. First, this paper analyzes the disparity clues and focus clues contained in the multi-view data set and the light field refocusing image set of the camera array, respectively, and points out the differences and relationships between the two depth clues extraction methods in the light field sampling frequency domain space, that is, the disparity method focuses on the energy concentration characteristics near the frequency domain spatial angle axis, while the focus method focuses on the high frequency proportion of energy distribution on the angle axis. Then, the weighted linear fusion method based on image gradient is used to fuse the two calculation results, which improves the accuracy and robustness of depth estimation. Finally, the results of depth estimation experiments on different sets of scenes show that compared with the method based on a single depth cue, the method in this paper has higher accuracy in depth calculation in discontinuous areas of scene depth and similar texture areas.

High genetic connectivity among morphologically differentiated populations of the black sea urchin Arbacia lixula (Echinoidea: Arbacioida) across the central African Mediterranean coast

The present study represents the first population structure analysis of the black sea urchin Arbacia lixula across part of its African Mediterranean distribution range, the Tunisian coast. This location is appropriate for the study of biogeographical processes given the presence of a well-known discontinuous biogeographic area (the Siculo-Tunisian Strait). Patterns of morphological and genetic variation in this highly dispersive echinoid species were assessed among its populations from the western and eastern Mediterranean coasts of Tunisia. A total of 109 specimens from six sites were collected and examined for morphometric variability in seven morphometric traits. Concordant results, inferred from CDA analyses, pairwise NPMANOVA comparisons and MDS plot, showed significant inter-population differences in the measured traits among the studied populations. In addition, UPGMA clustering and discriminant/Hotelling analysis enabled the delineation of two morphologically differentiated groups assigned to the western and eastern Mediterranean basins. SIMPER analysis showed that total dry weight and test diameter were major contributors to the morphometric separation between locations and among groups. Despite the extensive morphological variation found in A. lixula, genetic analysis of the mitochondrial COI marker recovered only a single evolutionary lineage and showed a lack of population structure as inferred from the results of one-level AMOVA and pairwise comparisons of genetic differentiation. Possible explanations for this genetic pattern are discussed. Notably, the lack of COI divergence patterns, highlighted by shallow genealogy associated with high haplotype diversity and low nucleotide diversity, together with a recent demographic expansion event retrieved from mismatch distribution and BSP analysis could be considered a residual effect of a recent evolutionary history of the species in the Mediterranean.

Healing in peri-implant gap with BMP-2 and systemic bisphosphonate is dependent on BMP-2 dose-A canine study.

The bone-implant interface of cementless orthopedic implants can be described as a series of uneven sized gaps with discontinuous areas of direct bone-implant contact. Bridging these voids and crevices by addition of an anabolic stimulus to increase new bone formation can potentially improve osseointegration of implants. Bone morphogenetic protein 2 (BMP-2) stimulates osteoblast formation to increase new bone formation but also indirectly stimulates osteoclast activity. In this experiment, we investigate the hypothesis that osseointegration, defined as mechanical push-out and histomorphometry, depends on the dose of BMP-2 when delivered as an anabolic agent with systemic administration of the anti-resorptive agent zoledronate to curb an increase in osteoclast activity. Four porous coated titanium implants (one with each of three doses of surface-applied BMP-2 (15 µg; 60 µg; 240 µg) and untreated) surrounded by a 0.75 mm empty gap, were inserted into the distal femurs of each of twelve canines. Zoledronate IV (0.1 mg/kg) was administered 10 days into the observation period of 4 weeks. Bone-implant specimens were evaluated by mechanical push-out test and histomorphometry. The 15 µg implants had the best fixation on all mechanical parameters and largest surface area covered with new bone compared to the untreated, 60 and 240 µg implants, as well as the highest volume of new bone in the implant gap compared to 60 and 240 µg implants. The results in a canine implant model demonstrated that a narrow range of BMP-2 doses have opposite effects in bridging an empty peri-implant gap with bone, when combined with systemic zoledronate. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1406-1414, 2018.

Change in Stiffness of Pavement Layers in the Linear Discontinuous Deformation Area

The underground mining exploitation causes deformations on the surface of the area which are classified as continuous or discontinuous. Mining deformations cause loosening or compression of the subsoil. Loosening has an impact on the reduction of the subsoil stiffness. As a result the reduction of subsoil stiffness causes loosening of construction layers built in that subsoil. Pavement is a specific case. If there happens to be loosening then the fatigue life of pavement is reduced and premature damages can be observed such as fatigue cracks or/and structural deformation. Discontinuous deformations are an especially interesting case. They not only cause the reduction of the stiffness of the subsoil and pavement layers but also cause rapid deterioration in roughness. Change of roughness is very dangerous especially on fast roads such as a highway. Lately there can be observed the so called linear discontinuous surface deformations in the lanes in the mining area. Unfortunately, the ‘in situ’ research, presenting experiments on the effect of linear discontinuous deformations on the pavement, is in short supply. It is especially crucial with regard to the design of pavement reinforcement and the specification of optimal length of the reinforced part of the road. The article presents the results of ‘in situ’ tests carried out on the chosen pavements where the so called linear discontinuous surface deformation has appeared. The genesis of the damage is connected with the underground mining exploitation. Falling Weight Deflectometer (FWD) has been used in researches. Measuring points were carried out with high frequency which helped to acquire a very interesting distribution of deflections. The distribution of deflections well shows the impact of linear discontinuous deformation on the changes in stiffness pavement layers. In the analysis of data from FWD there has been used back calculation which worked modulus of layers out. The results of researches and analysis have allowed to specify the scale of stiffness reduction of subsoil and pavement layers and, above all, to specify a minimal area of reinforcement. Therefore, the results of the analysis can be very helpful in determining the range of reinforcement as well as designing reinforcement. Of course, researches should be continued for better knowledge about the impact of discontinuous deformations on pavement.

Mycophenolate Mofetil-Related Colitis: Endoscopic and Histologic Findings

Mycophenolate Mofetil (MMF) is a commonly used agent for immunosuppression in solid organ transplant recipients. It is typically well tolerated, but patients can develop colitis, with histologic changes including crypt distortion, and increased apoptosis, with patterns similar to IBD and GVHD. The mechanism of injury is unclear, but blocking of purine synthesis in enterocytes and antibacterial effect of MMF is thought to play a role. We present a case of a 39-year old female with a past medical history of end-stage renal disease, s/p deceased donor renal transplant in 2009, who presented for evaluation of diarrhea. She had noted two weeks of diarrhea and abdominal cramping. She denied recent antibiotic usage or travel. Her home medications included acyclovir, mycophenolate mofetil (on for 2 years), tacrolimus, and sirolimus. Her examination was notable for a temperature of 101 degrees Fahrenheit, and an abdomen which was soft, with bilateral lower quadrant tenderness without rebound, guarding, or rigidity. She had a normal CBC, but had an acutely elevated creatinine of 2.5mg/dL. Her Clostridium difficle PCR and stool cultures were negative. A CT scan of the abdomen and pelvis was normal. A colonoscopy showed discontinuous areas of ulcerated mucosa in the sigmoid through ascending colon. Also found was scattered inflammation characterized by congestion, erythema and shallow ulcerations throughout the entire colon. Histology results showed colonic tissue with crypt distortion, disarray and dropout. Crypt abscesses and scattered apoptotic bodies were also seen. The lamina propria showed an eosinophilic rich infiltrate. It was noted that the lack of dense lymphoplasmacytic infiltrate in the lamina propria made inflammatory bowel disease less likely. Mycophenolate mofetil induced colitis was the favored diagnosis, although it was noted that GVHD can have a similar histologic presentation. After the diagnosis was made, her MMF dose was decreased from 1000mg twice daily to 500 mg twice daily. Within days, the patient noted improvement in her symptoms and was discharged. This case highlights that MMF induced colitis should be a part of a clinician's differential in a patient presenting with diarrhea, regardless of duration of use. It also adds to the sparse body of literature describing the endoscopic and histologic features. This is an important clinical entity to recognize given the widespread use of this medication in the transplant population.Figure: Coronal FDG PET/ CT scan demonstrating indeterminate intensely avid FDG enhancing colonic change in the descending colon (3 cm in length) with a 1:1 correlation with endoscopic findings.

Geography and past climate changes have shaped the evolution of a widespread lizard from the Chilean hotspot

The complex orogenic history and structure of Southern South America, coupled with Pleistocene glacial cycles, have generated paleoclimatic and environmental changes that influenced the spatial distribution and genetic composition of natural populations. Despite the increased number of phylogeographic studies in this region and given the frequent idiosyncratic phylogeographic patterns, there is still the need to focus research especially on species that are currently distributed within a wide range of bioclimatic regimes, and that historically have been subject to contrasting scenarios. Liolaemus tenuis is a widely distributed lizard species inhabiting latitudinally in almost 1000km through central and southern Chile. Here we describe the geographical patterns of genetic variation and lineage diversification within L. tenuis, and their association with geography and Pleistocene glaciations, using sequences from one mitochondrial and two nuclear genes, and five microsatellite loci, and covering most of the species distributional range. Our results revealed a high diversity both within and among populations, as well as two phylogeographic breaks, which are consistent with two of the larger rivers of central Chile, the Maipo and Biobío Rivers. Liolaemus tenuis is characterized by several allopatric lineages, especially in its north and central range, which suggest a history of multiple vicariance processes. Conversely, populations found in the southern range, south of the Biobío River, show signatures of recent decreases in effective population sizes, coupled with recent range expansions and secondary contact. Niche “envelope” data are consistent with patterns of genetic variation; both suggest a history of discontinuous areas of relatively stable populations throughout all of the distribution of L. tenuis. These data are also consistent with higher probabilities of habitat suitability north of the Maipo River (ca. 33°S), in both coastal areas and the “Intermediate Depression” between 34° and 37°S, as well as in the southern Coastal Cordillera between the Biobío and Araucanía regions. Interestingly, both molecular and niche envelope modeling data suggest that some populations may have persisted in fragmented refugia in Andean valleys, within the limits of the ice sheet. Finally, our results suggest that several populations of L. tenuis colonized glaciated regions from refugial areas in lowlands and coastal regions, and in the southern distribution, historic migration events would have occurred from refugial areas within the limits of the ice sheet.

Formation of metastable phases of ferrous sulfide via pulsed Nd:YAG laser deposition: Experimental and theoretical study

Highly polymorphic ferrous sulfide exhibits attractive optical, semiconducting, magnetic and biocatalytic properties related to its phase modification. Nd:YAG laser ablation of ferrous sulfide (FeS) in vaccum results in noncongruent deposition of nanostructured FeS1-x thin films. Deposits have been carried out on Ta, Al and Cu substrates and achieved thin films were analyzed using scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and electron diffraction in order to characterize morphology, chemical composition and phase transformation induced by ablative process. Round-shaped and ring-like particles, shapeless agglomerates as well as flat discontinuous areas have been observed for all the coats deposited on various substrates. However, using HRTEM, in agreement with electron diffraction, different phase compositions on various substrates have been detected. Cubic pyrite phase (FeS2) has been detected on Ta substrate. Metastable rhombohedral smythite Fe9S11 and cubic pyrite FeS2 have been found on Al substrate. And cubic pyrite FeS2, metastable rhombohedral smythite Fe9S11 and metastable orthorhombic marcasite FeS2m have been revealed on Cu substrate. The detected crystalline nanograins in all deposits were surrounded by amorphous phase. Furthermore, to gain deep insight into the electronic structure of obtained stable (cubic pyrite) and less known unstable phases (orthorhombic marcasite and rhombohedral smythite) the density functional theory is employed and important characteristics such as band gap values have been calculated.

Three-Dimensional Reconstruction and Visualization of Human Enamel Ex Vivo Using High-Frequency Ultrasound

Dental decay and erosion are common cases in clinics. It would be useful for dentists to collect adequate information about the thickness of hard tissue (e.g., enamel and dentin) during treatment without pulp exposure. This study proposes a scanning system that collects structural information of the tooth surface and enamel-dentine junction. A three-dimensional (3D) motorized scanning stage is used to control the movement trajectories of an A-mode transducer to acquire echoes from the surface of a tooth. The 3D form of enamel is reconstructed using this system. By adopting a gain compensation method for radio-frequency signals, no special preparation is required before scanning. Despite some discontinuous areas in the 3D images, the 3D representations of human molars well duplicated the real samples and the thickness of enamel could be measured. Based on micro-computed tomography data, the overall measurement error of the proposed system is 3.55%, indicating good performance for clinical application.