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Lateral Growth (lateral + growth)
Selected AbstractsLarge area lateral overgrowth of mismatched InGaP on GaAs(111)B substratesCRYSTAL RESEARCH AND TECHNOLOGY, Issue 12 2005S. Uematsu Abstract Application of InGaAs/InGaP double-heterostructure (DH) lasers increases the band offset between the cladding layer and the active layer more than the use of conventional 1.3 µm InGaAsP/InP lasers. As a first step in realizing 1.3 µm InGaP/InGaAs/InGaP DH lasers, we proposed InGaP lattice-mismatched epitaxial lateral overgrowth (ELO) technique and successfully carried out the InGaP growth on both GaAs (100), (111)B and InP (100) substrates by liquid phase epitaxy. In this work, we grew the InGaP crystal on GaAs (111)B substrate by adjusting Ga and P composition in In solution, to obtain In0.79Ga0.21P (, = 820 nm) virtual substrate for 1.3 µm InGaAs/InGaP DH lasers. To grow the InGaP all over the lateral surface of the substrate, the growth time was extended to 6 hours. The amount of InGaP lateral growth up to 2 hours was gradually increased, but the lateral growth was saturated. The InGaP lateral width was about 250 µm at the growth time of 6 hours. We report the result that optical microscope observation, CL and X-ray rocking curve measurements and reciprocal lattice space mapping were carried out to evaluate the crystal quality of the grown InGaP layers. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Relationship between stump treatment coverage using the biological control product PG Suspension, and control of Heterobasidion annosum on Corsican pine, Pinus nigra ssp. laricioFOREST PATHOLOGY, Issue 1 2008K. V. Tubby Summary The relationship between the proportion of the stump surface covered by the biological stump treatment agent PG Suspension, containing Phlebiopsis gigantea and its efficacy against the pathogen Heterobasidion annosum sensu stricto was studied during a first thinning of Corsican pine (Pinus nigra ssp. laricio) in Thetford Forest, UK. PG Suspension was manually applied to 100%, 75%, 50% or 0% of the surface of 150 stumps. Spores of H. annosum were inoculated onto 75 of the stumps, and the remaining stumps exposed to natural airborne spore deposition. The relationship between coverage and efficacy was found to be quantitative. Covering all the stump surface with PG Suspension completely excluded the pathogen, whereas stumps not treated with PG Suspension (the 0% treatment) became infected with H. annosum. Partial (75%) PG Suspension coverage resulted in the pathogen colonizing 40% of stumps following artificial inoculation with H. annosum, and just 7% of stumps exposed to ambient H. annosum spore infection. Decreasing levels of coverage allowed increasing areas of the stump surface to be colonized by H. annosum. Some small gaps in coverage were closed by lateral growth of P. gigantea, but it is recommended that operators aim for full stump coverage to give complete protection against H. annosum. [source] Interactions of multiple disturbances in shaping boreal forest dynamics: a spatially explicit analysis using multi-temporal lidar data and high-resolution imageryJOURNAL OF ECOLOGY, Issue 3 2010Udayalakshmi Vepakomma Summary 1.,Mixed-wood boreal forests are often considered to undergo directional succession from shade-intolerant to shade-tolerant species. It is thus expected that overstorey gaps should lead to the recruitment of shade-tolerant conifers into the canopy in all stand development stages and that the recruitment of shade-intolerant hardwoods would be minimal except in the largest gaps. 2.,We analysed short-term gap dynamics over a large 6-km2 spatial area of mixed-wood boreal forest across a gradient of stands in different developmental stages with different times of origin since fire (expressed as stand ,age') that were affected differentially by the last spruce budworm (SBW) outbreak. Structural measurements of the canopy from lidar data were combined with spectral classification of broad species groups to characterize the gap disturbance regime and to evaluate the effect of gap openings on forest dynamics. 3.,Estimated annual gap opening rates increased from 0.16% for 84-year-old stands to 0.88% for 248-year-old stands. Trees on gap peripheries in all stands were more vulnerable to mortality than interior canopy trees. 4.,Due to recovery from the last SBW outbreak 16 years previously, gap closure rates were higher than opening rates, ranging from 0.44% to 2.05% annually, but did not show any relationship with stand age. There was, however, a continuing legacy of the last SBW outbreak in old-conifer stands in terms of a continued high mortality of conifers. In all stands, the majority of the openings were filled from below, although a smaller but significant proportion filled from lateral growth of gap edge trees. 5.,Synthesis. The forest response to moderate- to small-scale disturbances in old-growth boreal forest counters the earlier assumption that the transition from one forest state to the next is slow and directional with time since the last fire. Overall, a small 6% increase in hardwoods was observed over 5 years, largely due to regeneration in-filling of hardwoods in gaps instead of successional transition to more shade-tolerant conifers. Gaps are vital for hardwood maintenance while transition to softwoods can occur without perceived gap-formation as overstorey trees die, releasing understorey trees. [source] Genetic loci influencing natural variations in femoral bone morphometry in mice,JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 4 2001Thomas A. Drake This study identifies genetic loci affecting femoral bone length and width measures in mature mice. Sixteen month old female F2 progeny of a C57BL/6J and DBA/2J intercross were examined for femur length and width of the femoral head, intertrochanteric region and three locations of the diaphysis using digitized images of femur radiographs obtained in the anterior-posterior and lateral projections. A genome wide linkage map was constructed using microsatellite markers at an average density of 20 cM, and quantitative trait locus analysis used to identify regions of the genome showing linkage with the traits measured. Femur length showed significant linkage with loci on proximal chromosome 3 (lod 6.1), and suggestive linkage with a locus on chromosome 14. A major locus on mid-chromosome 7 controlled width of the diaphysis (lod 6.8). Other loci were identified on chromosomes 2 and 4. Width at the intertrochanteric region had suggestive linkage with loci on chromosomes 6 and 19. No loci were found with linkage for width of the femoral head. Candidate genes related to bone development or metabolism are present at most of these loci. These findings show that genetic regulation of femoral bone morphology is complex, and are consistent with the distinct biologic processes that control longitudinal and lateral growth of the femur. © 2001 Orthopaedic Research Society. Punlished by Elsevier Science Ltd. All rights reserved. [source] Spatial patterns of microsite colonisation on two young lava flows on Mount Hekla, IcelandJOURNAL OF VEGETATION SCIENCE, Issue 2 2008N.A. Cutler Abstract Questions: How does vegetation first establish on newly-formed lava substrates? Do very small (cm) and meso-scale (m) variations in the physical environment influence this process and subsequent vegetation development? Location: Mount Hekla, southern Iceland (64°00' N, 19°40' W). Methods: Data on vegetation structure and the incidence of ,safe sites' suitable for colonisation were collected from high and low points on the surfaces of lava flows emplaced during the 1991 and 2000 A.D. eruptions of Mount Hekla. Effects of flow age and meso-topographic position on vegetation structure (moss cover, patch density, stem length) were assessed by two-way analyses of variance. The distributions of colonisation events and available safe sites were analysed using point pattern techniques. Results: Rapid colonisation of the lava surface was observed, despite stressful environmental conditions. The 1991 and 2000 flows differed significantly in vegetation structure, but there were no significant differences in moss cover, patch density and stem length between ,high' and ,low' sites. Conclusions: Colonisation events are invariably associated with small-scale irregularities on the surface of the lava. The colonisation process appears to be spatially random. Development of the moss ,carpet' proceeds by vertical thickening and lateral growth and coalescence of moss patches that establish in ,safe sites'. This process is rapid, with close to 100% of available safe sites exploited within 20 years. Topographic position makes no difference to the very early stages of vegetation development and cannot be used to ,forecast' the later stages of development. [source] Impact craters on small icy bodies such as icy satellites and comet nucleiMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2005M. J. Burchell ABSTRACT Laboratory data and the results of modelling are combined to predict the possible size of craters in icy bodies such as a comet nucleus. This is done in particular for the case of a a 370-kg mass impacting a body the size of the nucleus of comet 9P/Temple-1 at 10 km s,1. This reproduces the Deep Impact comet impact to occur in 2005, when a NASA spacecraft will observe at close range an impact on the comet nucleus of an object deployed from the main spacecraft. The predicted crater size depends not only on uncertainties in extrapolation from laboratory scale and the modelling in general, but also on assumptions made about the nature of the target. In particular, allowance is made for the full range of reasonable target porosities; this can significantly affect the outcome of the Deep Impact event. The range of predicted crater sizes covers some 7,30 m crater depth and some 50,150 m crater diameter. An increasingly porous target (i.e. one with a higher percentage of void space) will increase the depth of the crater but not necessarily the diameter, leading to the possibility of an impact event where much of the crater formation is in the interior of the crater, with work going into compaction of void space and some possible lateral growth of the crater below the surface entrance. Nevertheless, for a wide range of scenarios concerning the nature of the impact, the Deep Impact event should penetrate the surface to depths of a few tens of metres, accessing the immediate subsurface regions. In parallel to this, the same extrapolation methods are used to predict the size of impactors that may have caused the features observed on the surfaces of small bodies, e.g. the Saturnian satellite Phoebe and the nucleus of comet P/Wild-2. [source] DC characteristics and high frequency response of GaN nanowire metal-oxide-semiconductor field-effect transistorPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue S2 2009Jeng-Wei Yu Abstract We report selected site lateral growth of crystalline [110] GaN nanowire (NW) with high channel mobility of 1050 cm2/V-s on SiO2/p-Si. This scheme enables photolithographic fabrication of top-gated GaN NW-MOSFET of 60 nm dia. and 2 ,m gate length. Device parameters with gm of 25 ,S, saturation current of 90 ,A, and cut-off frequency fT at 14 GHz have been extracted. In an active load configuration of GaN NW-MOSFET inverter we reported voltage gain of 2 and a high current on/off ratio of 104. These observations suggest promising functional diversification of the GaN NW-MOSFET on the Si-based CMOS platform for the sub-50 nm technology nodes. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] TEM characterization of VLS-grown ZnTe nanowiresPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 12 2008H. Kirmse Abstract ZnTe nanowires were grown via a vapour-liquid-solid pro- cess. Nano-sized droplets of a gold-based eutectic act as catalysts. The comprehensive transmission electron microscopy studies reveal that the nanowires are single crystals with numerous stacking faults and twins. The dimension of the wires is several micrometers in length and a few tens of nanometers in diameter. At the sidewall of the nanowires additional nanocrystals of ZnO embedded in an amorphous layer are identified. The formation process of the nanowires can be understood as a two-step process. The first step is the one-dimensional growth along the wire axis by consuming all the material deposited near the droplet. In a second step, facets are formed due to lateral growth of the nanowire. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] M -plane InGaN/GaN light emitting diodes fabricated by MOCVD regrowth on c -plane patterned templatesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 9 2008Christopher A. Schaake Abstract In this work we demonstrate a light emitting diode (LED) with m -plane quantum wells fabricated on a (000) template. N-polar, n-type GaN was grown by MOCVD on vicinal sapphire substrates. Stripes, measuring 500 nm wide, 500 nm tall and spaced 2 ,m apart, were etched parallel to the ,110, direction leading to sidewalls that are approximately {100}. Sputtered AlN was used as a regrowth mask on the c -plane surfaces. An active region consisting of 5 InGaN quantum wells and GaN barriers followed by p-type was grown. The regrowth occurred mostly on the exposed m -plane sidewalls, leading to lateral growth in the ,100, direction. The LED was processed using conventional methods. A thick metal contact was used to connect the p-regions together. Current vs. voltage measurements showed good rectifying behavior with a turn on of about 6 volts. On-wafer electroluminescence measurements revealed a peak wavelength of 422 nm. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The effect of Ge doping for lattice-mismatched InGaP/InP (100) with epitaxial lateral overgrowthPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 8 2006Kenichi Higuchi Abstract We have proposed the use of 1.3 ,m InGaAs/InGaP laser on an InP (100) substrate to reduce the leakage current. Because of the lattice-mismatch between InP and InGaP, epitaxial lateral overgrowth (ELO) technique is used. Ge doping is an effective way of increasing the amount of lateral growth in InP/InP lattice-matched ELO. In the InGaP/InP lattice-mismatched ELO, the crystal defects of the Ge-doped InGaP layer decrease compared to undoped sample. The Ge doping is effective for growing InGaP/InP with high crystalline quality by ELO. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Fold evolution and drainage development in the Zagros mountains of Fars province, SE IranBASIN RESEARCH, Issue 1 2008Lucy A. Ramsey ABSTRACT A central question in structural geology is whether, and by what mechanism, active faults (and the folds often associated with them) grow in length as they accumulate displacement. An obstacle in our understanding of these processes is the lack of examples in which the lateral growth of active structures can be demonstrated definitively, as geomorphic indicators of lateral propagation are often difficult, or even impossible to distinguish from the effects of varying lithology or non-uniform displacement and slip histories. In this paper we examine, using the Zagros mountains of southern Iran as our example, the extent to which qualitative analysis of satellite imagery and digital topography can yield insight into the growth, lateral propagation, and interaction of individual fold segments in regions of active continental shortening. The Zagros fold-and-thrust belt contains spectacular whaleback anticlines that are well exposed in resistant Tertiary and Mesozoic limestone, are often >100 km in length, and which contain a large proportion of the global hydrocarbon reserves. In one example, Kuh-e Handun, where an anticline is mantled by soft Miocene sediments, direct evidence of lateral fold propagation is recorded in remnants of consequent drainage patterns on the fold flanks that do not correspond to the present-day topography. We suggest that in most other cases, the soft Miocene and Pliocene sediments that originally mantled the folds, and which would have recorded early stages in the growth histories, have been completely stripped away, thus removing any direct geomorphic evidence of lateral propagation. However, many of the long fold chains of the Zagros do appear to be formed from numerous segments that have coalesced. If our interpretations are correct, the merger of individual fold segments that have grown in length is a major control on the development of through-going drainage and sedimentation patterns in the Zagros, and may be an important process in other regions of crustal shortening as well. Abundant earthquakes in the Zagros show that large seismogenic thrust faults must be present at depth, but these faults rarely reach the Earth's surface, and their relationship to the surface folding is not well constrained. The individual fold segments that we identify are typically 20,40 km in length, which correlates well with the maximum length of the seismogenic basement faults suggested from the largest observed thrusting earthquakes. This correlation between the lengths of individual fold segments and the lengths of seismogenic faults at depth suggest that it is possible, at least in some cases, that there may be a direct relationship between folding and faulting in the Zagros, with individual fold segments underlain by discrete thrusts. [source] Stratigraphic and structural expression of the lateral growth of thrust fault-propagation folds: results and implications from kinematic modellingBASIN RESEARCH, Issue 2 2003Kate A. Cooper In order to better understand the development of thrust fault-related folds, a 3D forward numerical model has been developed to investigate the effects that lateral slip distribution and propagation rate have on the fold geometry of pre- and syn-tectonic strata. We consider a fault-propagation fold in which the fault propagates upwards from a basal decollement and along-strike normal to transport direction. Over a 1 Ma runtime, the fault reaches a maximum length of 10 km and accumulates a maximum displacement of 1 km. Deformation ahead of the propagating fault tip is modelled using trishear kinematics while backlimb deformation is modelled using kink-band migration. The applicability of two different lateral slip distributions, namely linear-taper and block-taper, are firstly tested using a constant lateral propagation rate. A block-taper slip distribution replicates the geometry of natural fold-thrusts better and is then used to test the sensitivity of thrust-fold morphology to varied propagation rates in a set of fault-propagation folds that have identical final displacement to length (Dmax/Lmax) ratios. Two stratigraphic settings are considered: a model in which background sedimentation rates are high and no topography develops, and a model in which a topographic high develops above the growing fold and local erosion, transport and deposition occur. If the lateral propagation rate is rapid (or geologically instantaneous), the fault tips quickly become pinned as the fault reaches its maximum lateral extent (10 km), after which displacement accumulates. In both stratigraphic settings, this leads to strike-parallel rotation of the syn-tectonic strata near the fault tips; high sedimentation rates relative to rates of uplift result in along-strike thinning over the structural high, while low sedimentation rates result in pinchout against it. In contrast, slower lateral propagation rates (i.e. up to one order of magnitude greater than slip rate) lead to the development of along-strike growth triangles when sedimentation rates are high, whereas when sedimentation rates are low, offflap geometries result. Overall we find that the most rapid lateral propagation rates produce the most realistic geometries. In both settings, time-equivalent units display both nongrowth and growth stratal geometries along-strike and the transition from growth to nongrowth has the potential to delineate the time of fault/fold growth at a given location. This work highlights the importance of lateral fault-propagation and fault tip pinning on fault and fold growth in three dimensions and the complex syn-tectonic geometries that can result. [source] Self-Organization of a Highly Integrated Silicon Nanowire Network on a Si(110),16,×,2 Surface by Controlling Domain GrowthADVANCED FUNCTIONAL MATERIALS, Issue 21 2009Ie-Hong Hong Abstract Here, bottom-up nanofabrication for the two-dimensional self-organization of a highly integrated, well-defined silicon nanowire (SiNW) mesh on a naturally-patterned Si(110),16,×,2 surface by controlling the lateral growths of two non-orthogonal 16,×,2 domains is reported. This self-ordered nanomesh consists of two crossed arrays of parallel-aligned SiNWs with nearly identical widths of 1.8,2.5,nm and pitches of 5.0,5.9,nm, and is formed over a mesoscopic area of 300,×,270,nm2 so as to show a high integration density in excess of 104,µm,2. These crossed SiNWs exhibit semiconducting character with an equal band gap of ,0.95,eV as well as unique quantum confinement effect. Such an ultrahigh-density SiNW network can serve as a versatile nanotemplate for nanofabrication and nanointegration of the highly-integrated metal-silicide or molecular crossbar nanomesh on Si(110) surface for a broad range of device applications. Also, the multi-layer, vertically-stacked SiNW networks can be self-assembled through hierarchical growth, which opens the possibility for creating three-dimensionally interconnected crossbar circuits. The ability to self-organize an ultrahigh-density, functional SiNW network on a Si(110) surface represents a simple step toward the fabrication of highly-integrated crossbar nanocircuits in a very straightforward, fast, cost-effective, and high throughput process. [source] | ||||||||||||||||