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Strand, Robin, Krzysztof Chris Ciesielski, Filip Malmberg y Punam K. Saha. "The minimum barrier distance". Computer Vision and Image Understanding 117, n.º 4 (abril de 2013): 429–37. http://dx.doi.org/10.1016/j.cviu.2012.10.011.
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Zhang, Jing Mao y Yan Xia Shen. "Spectral segmentation via minimum barrier distance". Multimedia Tools and Applications 76, n.º 24 (20 de febrero de 2017): 25713–29. http://dx.doi.org/10.1007/s11042-017-4473-8.
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Džambas, Tamara, Saša Ahac y Vesna Dragčević. "The Influence of Visibility Conditions in Horizontal Road Curves on the Efficiency of Noise Protection Barriers". Romanian Journal of Transport Infrastructure 2, n.º 2 (1 de diciembre de 2013): 22–32. http://dx.doi.org/10.1515/rjti-2015-0016.
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Abstract Ensuring sufficient visibility on planned roads by sight distance testing is an integral part of every project, but problems with visibility can emerge when noise barriers are erected on existing roads. Namely, in order to provide sufficient noise protection, high noise barriers are often placed at minimum distance from the carriageway edge, and additional visibility testing in most cases is not carried out. Research described in this paper consists of stopping sight distance tests conducted by means of specialized road design software MX Road, and noise barrier optimization conducted by means of specialized noise prediction software LimA using static noise calculation method RLS 90. The aim of this research is to establish whether the required stopping sight distance on road sections where minimum design parameters are applied can be achieved if the noise barrier is placed at minimum distance from the carriageway edge, and to establish whether the optimized dimensions of planned noise protection barrier will change if the barrier is placed on larger distance from the noise source, which is, in this case, the existing road.
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Ciesielski, Krzysztof Chris, Robin Strand, Filip Malmberg y Punam K. Saha. "Efficient algorithm for finding the exact minimum barrier distance". Computer Vision and Image Understanding 123 (junio de 2014): 53–64. http://dx.doi.org/10.1016/j.cviu.2014.03.007.
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Ôn Vũ Ngọc, Minh, Nicolas Boutry, Jonathan Fabrizio y Thierry Géraud. "A minimum barrier distance for multivariate images with applications". Computer Vision and Image Understanding 197-198 (agosto de 2020): 102993. http://dx.doi.org/10.1016/j.cviu.2020.102993.
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Tu, Zhengzheng, Linlin Guo, Chenglong Li, Ziwei Xiong y Xiao Wang. "Minimum Barrier Distance-Based Object Descriptor for Visual Tracking". Applied Sciences 8, n.º 11 (13 de noviembre de 2018): 2233. http://dx.doi.org/10.3390/app8112233.
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In most visual tracking tasks, the target is tracked by a bounding box given in the first frame. The complexity and redundancy of background information in the bounding box inevitably exist and affect tracking performance. To alleviate the influence of background, we propose a robust object descriptor for visual tracking in this paper. First, we decompose the bounding box into non-overlapping patches and extract the color and gradient histograms features for each patch. Second, we adopt the minimum barrier distance (MBD) to calculate patch weights. Specifically, we consider the boundary patches as the background seeds and calculate the MBD from each patch to the seed set as the weight of each patch since the weight calculated by MBD can represent the difference between each patch and the background more effectively. Finally, we impose the weight on the extracted feature to get the descriptor of each patch and then incorporate our MBD-based descriptor into the structured support vector machine algorithm for tracking. Experiments on two benchmark datasets demonstrate the effectiveness of the proposed approach.
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Yang, Zhi-yuan y Bin Wu. "Minimum barrier distance based tracking via spatio-temporal context learning". Optoelectronics Letters 15, n.º 1 (enero de 2019): 75–80. http://dx.doi.org/10.1007/s11801-019-8090-9.
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Wang, Anzhi y Minghui Wang. "RGB-D Salient Object Detection via Minimum Barrier Distance Transform and Saliency Fusion". IEEE Signal Processing Letters 24, n.º 5 (mayo de 2017): 663–67. http://dx.doi.org/10.1109/lsp.2017.2688136.
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NAZAROV, V. N., K. YU SAMSONOV y E. G. EKOMASOV. "ONE-DIMENSIONAL DYNAMICS OF THE DOMAIN BOUNDARY IN A SEVEN-LAYER FERROMAGNETIC STRUCTURE". Izvestia Ufimskogo Nauchnogo Tsentra RAN, n.º 1 (31 de marzo de 2023): 19–23. http://dx.doi.org/10.31040/2222-8349-2023-0-1-19-23.
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The dynamics of the domain boundary is considered using the example of a seven-layer ferromagnetic structure with three thin and four wide magnetic layers. The structure of the domain boundary is represented as a kink solution of the sine-Gordon equation. The equation of motion for magnetization was solved numerically using an explicit scheme. The discretization of the equation was carried out according to a standard five-point scheme of the "cross" type. The paper shows the features of the dynamics of the domain boundary in a multilayer magnetic system in the presence of thin magnetic layers with an increased value of the magnetic anisotropy constant. Thin layers with an increased value of the magnetic anisotropy constant compared to the homogeneous state represent potential barriers to the moving domain boundary. Thin layers with an increased magnitude of magnetic anisotropy compared to a homogeneous state represent potential barriers to a moving domain boundary. A diagram of possible scenarios of the dynamics of the domain boundary is constructed depending on the initial velocity of its movement and the distance between three thin magnetic layers. The maximum value of the kink velocity for reflection from all potential barriers, depending on their size, is obtained. With an increase in the height and width of the barrier, the value of such a threshold maximum reflection velocity of the domain boundary increases nonlinearly. With a sufficiently high barrier height, there is already an almost linear dependence on the width of this threshold velocity. With a slight increase in the speed of movement of the domain boundary, the kink can pass through the first barrier, but it is reflected from the second barrier. There is also a case of kink oscillation between the second and third potential barriers. Such fluctuations are clearly inharmonious. The dependence of the threshold velocity on the distance between the barriers is obtained. As the distance between the barriers increases, the threshold speed value tends to a value equal to the threshold speed for one barrier. In the work, the minimum value of the speed of the domain boundary of the passage of all layers, depending on the parameters of potential barriers, is obtained. It is also found that there is a critical distance separating the dynamics of the domain boundary into two regions with qualitatively different behavior of the system.
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Chang, C., M. J. Chung y Z. Bien. "Collision-free motion planning for two articulated robot arms using minimum distance functions". Robotica 8, n.º 2 (abril de 1990): 137–44. http://dx.doi.org/10.1017/s0263574700007712.
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SummaryThis paper presents a collision-free motion planning method of two articulated robot arms in a three dimensional common work space. Each link of a robot arm is modeled by a cylinder ended by two hemispheres, and the remaining wrist and hand is modeled by a sphere. To describe the danger of collision between two modeled objects, minimum distance functions, which are defined by the Euclidean norm, are used. These minimum distance functions are used to describe the constraints that guarantee no collision between two robot arms. The collision-free motion planning problem is formulated as a pointwise constrained nonlinear minimization problem, and solved by a conjugate gradient method with barrier functions. To improve the minimization process, a simple grid technique is incorporated. Finally, a simulation study is presented to show the significance of the proposed method.
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Kim, Seungwon, Taejin Jang, Topendra Oli y Cheolwoo Park. "Behavior of Barrier Wall under Hydrogen Storage Tank Explosion with Simulation and TNT Equivalent Weight Method". Applied Sciences 13, n.º 6 (15 de marzo de 2023): 3744. http://dx.doi.org/10.3390/app13063744.
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Hydrogen gas storage place has been increasing daily because of its consumption. Hydrogen gas is a dream fuel of the future with many social, economic and environmental benefits to its credit. However, many hydrogen storage tanks exploded accidentally and significantly lost the economy, infrastructure, and living beings. In this study, a protection wall under a worst-case scenario explosion of a hydrogen gas tank was analyzed with commercial software LS-DYNA. TNT equivalent method was used to calculate the weight of TNT for Hydrogen. Reinforced concrete and composite protection wall under TNT explosion was analyzed with a different distance of TNT. The initial dimension of the reinforced concrete protection wall was taken from the Korea gas safety code book (KGS FP217) and studied the various condition. H-beam was used to make the composite protection wall. Arbitrary-Lagrangian-Eulerian (ALE) simulation from LS-DYNA and ConWep pressure had a good agreement. Used of the composite structure had a minimum displacement than a normal reinforced concrete protection wall. During the worst-case scenario explosion of a hydrogen gas 300 kg storage tank, the minimum distance between the hydrogen gas tank storage and protection wall should be 3.6 m.
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Chen, Dong, Fei Gao, Hui-Qiu Deng, Bo Liu, Wang-Yu Hu y Xin Sun. "Migration of defect clusters and xenon-vacancy clusters in uranium dioxide". International Journal of Modern Physics B 28, n.º 18 (3 de junio de 2014): 1450120. http://dx.doi.org/10.1142/s0217979214501203.
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The possible transition states, minimum energy paths (MEPs) and migration mechanisms of defect clusters and xenon-vacancy defect clusters in uranium dioxide ( UO 2) have been investigated using the dimer and the nudged elastic-band (NEB) methods. The nearby O atom can easily hop into the oxygen vacancy position by overcoming a small energy barrier, which is much lower than that for the migration of a uranium vacancy. A simulation for a vacancy cluster consisting of two oxygen vacancies reveals that the energy barrier of the divacancy migration tends to decrease with increasing the separation distance of divacancy. For an oxygen interstitial, the migration barrier for the hopping mechanism is almost three times larger than that for the exchange mechanism. Xe moving between two interstitial sites is unlikely a dominant migration mechanism considering the higher energy barrier. A net migration process of a Xe-vacancy pair containing an oxygen vacancy and a xenon interstitial is identified by the NEB method. We expect the oxygen vacancy-assisted migration mechanism to possibly lead to a long distance migration of the Xe interstitials in UO 2. The migration of defect clusters involving Xe substitution indicates that Xe atom migrating away from the uranium vacancy site is difficult.
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MILLER, KATHRYN, NORMA McGOUGH y HEIDI URWIN. "Catering Gluten-Free When Simultaneously Using Wheat Flour". Journal of Food Protection 79, n.º 2 (1 de febrero de 2016): 282–87. http://dx.doi.org/10.4315/0362-028x.jfp-15-213.
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ABSTRACT A European law on gluten-free (GF) labeling came into force in 2012, covering foods sold prepacked and in food service establishments, and a similar U.S. Food and Drug Administration (FDA) regulation covers GF labeling from August 2014. Gluten is found in the grains wheat, rye, and barley. A common source of gluten in the kitchen is wheat flour. This research aimed to determine variables that have a significant effect on gluten contamination in commercial kitchens when wheat flour is in use and to establish controls necessary to assure GF production. A pilot study was used to test the following hypotheses: (i) increasing duration of exposure to wheat flour would increase gluten contamination, (ii) increasing distance between the site of preparation and the site of wheat flour would reduce gluten contamination, (iii) the use of a ventilation hood would decrease gluten contamination, and (iv) the use of a barrier segregating the site of preparation of a GF meal and the use of wheat flour would decrease gluten contamination. Petri dishes containing GF rice pudding were placed in three directions at increasing distances (0.5 to 2 m) from a site of wheat flour use. A barrier was in place between a third of samples and the site of wheat flour. After wheat flour was handled for 0.5 and 4.0 h, petri dishes were sealed and the contents were analyzed for gluten. The experiment was duplicated with the ventilation hood on and off. The pilot study revealed that a distance of 2 m from the use of wheat flour was required to control gluten contamination at ≤20 ppm if wheat flour had been in use for 4.0 h. The identified control of distance was tested in five different study sites. In each of the study sites, a test meal was prepared a minimum of 2 m away from the site of wheat flour use. Although kitchens vary and must be considered individually, the established control of a minimum 2-m distance, along with good hygiene practices, was found to be effective in preparing GF meals at all five study sites.
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Bayly, C. I. y F. Grein. "Alkyl versus hydrogen substitution: an abinitio study of the addition of hydroxide to formaldehyde and to acetone". Canadian Journal of Chemistry 67, n.º 1 (1 de enero de 1989): 176–82. http://dx.doi.org/10.1139/v89-029.
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The reaction profiles of the anionic nucleophilic addition of hydroxide to formaldehyde (system I) and to acetone (system II) were studied using theoretical abinitio methods. Calculations were carried out using the 4-31G basis set augmented with polarization and diffuse functions on some atoms. Electron correlation calculations were performed at the MP2 (frozen core), MP2, and MP4 levels for system I and at the MP2 (frozen core) level for system II. For both systems a local energy maximum was found at a C—OH distance of 2.5 Å. The barrier maximum was at lower energy than the separated reactants (−17.2 kcal/mol for system I and −5.6 kcal/mol for system II). This type of reaction profile is in accordance with a previous study on a prototype reaction. The energy difference between the barrier maximum and the secondary minimum (towards the reactants) was very small for system I (0.7 kcal/mol), but higher for system II (5.4 kcal/mol). The geometries of the two systems differed significantly in the region of the reaction coordinate containing the barrier and the secondary minimum. Keywords: quantum chemical study, addition of OH− to H2CO, addition of OH− to (CH3)2CO, alkyl versus hydrogen substitution, potential energy curve.
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Semakova, Anna A., Kirill S. Ovchinnikov y Alexey S. Matveev. "Self-deployment of mobile robotic networks: an algorithm for decentralized sweep boundary coverage". Robotica 35, n.º 9 (9 de agosto de 2016): 1816–44. http://dx.doi.org/10.1017/s0263574716000539.
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SUMMARYSeveral non-holonomic Dubins-car-like robots travel over paths with bounded curvatures in a plane that contains an a priori unknown region. The robots are anonymous to one another and do not use communication facilities. Any of them has access to the current minimum distance to the region and can determine the relative positions and orientations of the other robots within a finite and given visibility range. We present a distributed navigation and guidance strategy under which every robot autonomously converges to the desired minimum distance to the region with always respecting a given safety margin, the robots do not collide with one another and do not get into clusters, and the entire team ultimately sweeps over the respective equidistant curve at a speed exceeding a given threshold, thus forming a kind of a sweeping barrier at the perimeter of the region. Moreover, this strategy provides effective sub-uniform distribution of the robots over the equidistant curve. Mathematically rigorous justification of the proposed strategy is offered; its effectiveness is confirmed by extensive computer simulations and experiments with real wheeled robots.
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Reza, Mohammad S., Syarifah N. Aqida, Mohd Radzi Mohd Toff y Dermot Brabazon. "Thermal Barrier Coatings on Laser Surface Modified AISI H13 Tool Steel Using Atmospheric Plasma Spray Technique". Key Engineering Materials 554-557 (junio de 2013): 603–10. http://dx.doi.org/10.4028/www.scientific.net/kem.554-557.603.
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This paper presents yttria-stabilized zirconia (YSZ) coating deposition on laser surface modified H13 tool steel using atmospheric plasma spray (APS) technique. A Praxair Plasma Spray System with SG-100 gun was used to deposit coating materials on laser-modified H13 tool steel substrate surface. A bond coat layer material was NiCrAlY alloy while the top coat was yttria stabilized zirconia (YSZ) with powder size distribution range of-106 μm to +45 μm. A 23design of experiment (DOE) was used to deposit bond coat and top coat powders with three controlled factors of input current, powder feed rate and stand-off-distance. The design was optimised for minimum porosity and maximum hardness. The coating thickness and percentage of porosity were measured using IM7000 inverted optical microscope. Hardness properties of top coating layer were measured by using MMT-X7 Matsuzawa Hardness Tester Machine with Vickers hardness scale. The microscopy findings indicated variations of coating thickness at different parameters settings. Samples at the highest current and powder feed rate and lowest stand-off distance settings produced a lower porosity percentage and higher hardness. A higher powder feed rate with the smallest stand-off-distance allowed melted powders to travel uniformly onto the substrate surface. These findings were significant to development of thermal barrier coatings on semi-solid forming die surface.
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Smirnova, Y. G. y M. Müller. "How does curvature affect the free-energy barrier of stalk formation? Small vesicles vs apposing, planar membranes". European Biophysics Journal 50, n.º 2 (6 de febrero de 2021): 253–64. http://dx.doi.org/10.1007/s00249-020-01494-1.
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AbstractUsing molecular simulations of POPC lipids in conjunction with the calculation of the Minimum Free-Energy Path (MFEP), we study the effect of strong membrane curvature on the formation of the first fusion intermediate—the stalk between a vesicle and its periodic image. We find that the thermodynamic stability of this hourglass-shaped, hydrophobic connection between two vesicles is largely increased by the strong curvature of small vesicles, whereas the intrinsic barrier to form a stalk, i.e., associated with dimple formation and lipid tails protrusions, is similar to the case of two, apposing, planar membranes. A significant reduction of the barrier of stalk formation, however, stems from the lower dehydration free energy that is required to bring highly curved vesicle into a distance, at which stalk formation may occur, compared to the case of apposing, planar membranes.
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Korzec, Dariusz, Florian Hoppenthaler, Anatoly Shestakov, Dominik Burger, Andrej Shapiro, Thomas Andres, Simona Lerach y Stefan Nettesheim. "Multi-Device Piezoelectric Direct Discharge for Large Area Plasma Treatment". Plasma 4, n.º 2 (25 de mayo de 2021): 281–93. http://dx.doi.org/10.3390/plasma4020019.
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The piezoelectric cold plasma generators (PCPG) allow for production of the piezoelectric direct discharge (PDD), which is a kind of cold atmospheric pressure plasma (APP). The subjects of this study are different arrays of PCPGs for large-area treatment of planar substrates. Two limiting factors are crucial for design of such arrays: (i) the parasitic coupling between PCPGs resulting in minimum allowed distance between devices, and (ii) the homogeneity of large area treatment, requiring an overlap of the activation zones resulting from each PCPG. The first limitation is investigated by the use of electric measurements. The minimum distance for operation of 4 cm between two PCPGs is determined by measurement of the energy coupling from an active PCPG to a passive one. The capacitive probe is used to evaluate the interference between signals generated by two neighboring PCPGs. The second limitation is examined by activation image recording (AIR). Two application examples illustrate the compromising these two limiting factors: the treatment of large area planar substrates by PCPG array, and the pretreatment of silicon wafers with an array of PCPG driven dielectric barrier discharges (DBD).
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Guan, Yi-Jun, Yong Ge, Hong-Xiang Sun, Shou-Qi Yuan y Xiao-Jun Liu. "Low-Frequency, Open, Sound-Insulation Barrier by Two Oppositely Oriented Helmholtz Resonators". Micromachines 12, n.º 12 (11 de diciembre de 2021): 1544. http://dx.doi.org/10.3390/mi12121544.
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In this work, a low-frequency, open, sound-insulation barrier, composed of a single layer of periodic subwavelength units (with a thickness of λ/28), is demonstrated both numerically and experimentally. Each unit was constructed using two identical, oppositely oriented Helmholtz resonators, which were composed of a central square cavity surrounded by a coiled channel. In the design of the open barrier, the distance between two adjacent units was twice the width of the unit, showing high-performance ventilation, and low-frequency sound insulation. A minimum transmittance of 0.06 could be observed around 121.5 Hz, which arose from both sound reflections and absorptions, created by the coupling of symmetric and asymmetric eigenmodes of the unit, and the absorbed sound energy propagating into the central cavity was greatly reduced by the viscous loss in the channel. Additionally, by introducing a multilayer open barrier, a broadband sound insulation was obtained, and the fractional bandwidth could reach approximately 0.19 with four layers. Finally, the application of the multilayer open barrier in designing a ventilated room was further discussed, and the results presented an omnidirectional, broadband, sound-insulation effect. The proposed open, sound-insulation barrier with the advantages of ultrathin thickness; omnidirectional, low-frequency sound insulation; broad bandwidth; and high-performance ventilation has great potential in architectural acoustics and noise control.
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Kamilan, Kamilan, Muhammad Syahrir Ramang, Heru Susilo, Fitriyana Fitriyana, Nurfadilah Nurfadilah y Auliansyah Auliansyah. "Economic Benefits and Governance of Guiding Barrier Fishing Gear in White-Spotted Spinefoot Fish Fishing Activities (Siganus canaliculatus, Park 1797) In Bontang City Waters". Economic and Social of Fisheries and Marine Journal 011, n.º 01 (18 de octubre de 2023): 77–88. http://dx.doi.org/10.21776/ub.ecsofim.2023.011.01.07.
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Guiding barrier fishing gear has been used in recent years in the mangrove, seagrass, and coral ecosystem areas of Bontang City. In previous studies, the main target, white-spotted spinefoot fish, has depreciated and degraded as a result of overfishing. This study calculates the economic benefits and attempts to analyze the management policy of guiding barrier fishing gear to overcome the depreciation and degradation problems. To calculate the economic benefits, the fisheries production approach was used, while the policy analysis used the interpretive structural model technique. During the peak season of white-spotted spinefoot fish, the average fisherman earns up to IDR400,750 per day, with a minimum of IDR103,000 and a maximum of IDR1,904,000. The optimal fishing period is nine months, after which fishermen will stop fishing in Ramadan, August, and September. There are six guiding barrier fishing gear management policies, namely: 1) open and close systems at the installation site; 2) increase the mesh size used; 3) reduce the number; 4) moratorium on new installations; 5) limit the number of owners for each fisherman; and 6) regulate the distance between guiding barrier fishing gear. Of the six policy alternatives, the top priority is to increase the mesh size used.
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Jamil, Arifa y M. A. Rafiq. "Low-temperature Electrical Properties and Correlated Barrier Hopping Conduction Mechanism in CdTiO3". Materials Innovations 02, n.º 03 (2022): 92–100. http://dx.doi.org/10.54738/mi.2022.2304.
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CdTiO3 nanoparticles were synthesized by solid-state reaction technique. X-ray diffraction (XRD) confirms the formation of rhombohedral CdTiO3 nanoparticles and scanning electron microscopy (SEM) shows the irregularly shaped nanoparticles. The ac conductivity data was fitted using Jonscher’s power law to find the frequency exponent "s". Correlated barrier hopping (CBH) is found to be prevailing conduction mechanism from 300 K to 160 K. The density of states (DOS) calculated by applying CBH model lie in the range of 2.89 x 1020 eV-1cm-3 to 2.96 x 1021 eV-1cm-3. The calculated minimum hopping distance (Rmin) was 2.13 x 10-9 m. The low values of tangent loss (< 1) at all temperatures suggest CdTiO3 as a potential material in electrical devices with low energy losses. The shifting of maxima towards higher frequencies with the decrease in temperature in imaginary modulus plots suggests the thermally triggered hopping process in CdTiO3 nanoparticles. The modulus studies confirm that hopping is the dominant conduction mechanism in CdTiO3 nanoparticles as suggested by ac conductivity studies
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Leverrier, Anthony, Simon Apers y Christophe Vuillot. "Quantum XYZ Product Codes". Quantum 6 (14 de julio de 2022): 766. http://dx.doi.org/10.22331/q-2022-07-14-766.
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We study a three-fold variant of the hypergraph product code construction, differing from the standard homological product of three classical codes. When instantiated with 3 classical LDPC codes, this "XYZ product" yields a non CSS quantum LDPC code which might display a large minimum distance. The simplest instance of this construction, corresponding to the product of 3 repetition codes, is a non CSS variant of the 3-dimensional toric code known as the Chamon code. The general construction was introduced in Denise Maurice's PhD thesis, but has remained poorly understood so far. The reason is that while hypergraph product codes can be analyzed with combinatorial tools, the XYZ product codes also depend crucially on the algebraic properties of the parity-check matrices of the three classical codes, making their analysis much more involved.Our main motivation for studying XYZ product codes is that the natural representatives of logical operators are two-dimensional objects. This contrasts with standard hypergraph product codes in 3 dimensions which always admit one-dimensional logical operators. In particular, specific instances of XYZ product codes with constant rate might display a minimum distance as large as Θ(N2/3). While we do not prove this result here, we obtain the dimension of a large class of XYZ product codes, and when restricting to codes with dimension 1, we reduce the problem of computing the minimum distance to a more elementary combinatorial problem involving binary 3-tensors. We also discuss in detail some families of XYZ product codes that can be embedded in three dimensions with local interaction. Some of these codes seem to share properties with Haah's cubic codes and might be interesting candidates for self-correcting quantum memories with a logarithmic energy barrier.
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Chen, Qing, Rong Sun, Ruixia Miao, Hanxiao Liu, Lulu Yang, Zengwei Qi, Wei He y Jianwei Li. "Novel SiGe/Si Heterojunction Double-Gate Tunneling FETs with a Heterogate Dielectric for High Performance". Micromachines 14, n.º 4 (31 de marzo de 2023): 784. http://dx.doi.org/10.3390/mi14040784.
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In this paper, a new SiGe/Si heterojunction double-gate heterogate dielectric tunneling field-effect transistor with an auxiliary tunneling barrier layer (HJ-HD-P-DGTFET) is proposed and investigated using TCAD tools. SiGe material has a smaller band gap than Si, so a heterojunction with SiGe(source)/Si(channel) can result in a smaller tunneling distance, which is very helpful in boosting the tunneling rate. The gate dielectric near the drain region consists of low-k SiO2 to weaken the gate control of the channel-drain tunneling junction and reduce the ambipolar current (Iamb). In contrast, the gate dielectric near the source region consists of high-k HfO2 to increase the on-state current (Ion) through the method of gate control. To further increase Ion, an n+-doped auxiliary tunneling barrier layer (pocket)is used to reduce the tunneling distance. Therefore, the proposed HJ-HD-P-DGTFET can obtain a higher on-state current and suppressed ambipolar effect. The simulation results show that a large Ion of 7.79 × 10−5 A/μm, a suppressed Ioff of 8.16 × 10−18 A/μm, minimum subthreshold swing (SSmin) of 19 mV/dec, a cutoff frequency (fT) of 19.95 GHz, and gain bandwidth product (GBW) of 2.07 GHz can be achieved. The data indicate that HJ-HD-P-DGTFET is a promising device for low-power-consumption radio frequency applications.
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Takizawa, Hiroki, Junichi Iwakiri, Goro Terai y Kiyoshi Asai. "Finding the direct optimal RNA barrier energy and improving pathways with an arbitrary energy model". Bioinformatics 36, Supplement_1 (1 de julio de 2020): i227—i235. http://dx.doi.org/10.1093/bioinformatics/btaa469.
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Abstract Motivation RNA folding kinetics plays an important role in the biological functions of RNA molecules. An important goal in the investigation of the kinetic behavior of RNAs is to find the folding pathway with the lowest energy barrier. For this purpose, most of the existing methods use heuristics because the number of possible pathways is huge even if only the shortest (direct) folding pathways are considered. Results In this study, we propose a new method using a best-first search strategy to efficiently compute the exact solution of the minimum barrier energy of direct pathways. Using our method, we can find the exact direct pathways within a Hamming distance of 20, whereas the previous methods even miss the exact short pathways. Moreover, our method can be used to improve the pathways found by existing methods for exploring indirect pathways. Availability and implementation The source code and datasets created and used in this research are available at https://github.com/eukaryo/czno. Supplementary information Supplementary data are available at Bioinformatics online.
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Mawhinney, Robert C., Heidi M. Muchall y Gilles H. Peslherbe. "A computational study of the 1,3-dipolar cycloaddition reaction mechanism for nitrilimines". Canadian Journal of Chemistry 83, n.º 9 (1 de septiembre de 2005): 1615–25. http://dx.doi.org/10.1139/v05-179.
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The [3+2] and [1+2] cycloaddition pathways between ethene and a series of 13 nitrilimines (R1CNNR2) have been examined by density functional theory [PBE0/6-311++G(2df,pd)] calculations. All reactions have low barriers ranging from 14.14 (R1 = CH3, R2 = H) to 1.01 (R1 = R2 = F) kcal mol1, and large reaction exothermicities consistent with the transient nature of nitrilimines. The [3+2] and [1+2] transition-state structures are very similar, mainly differing in the relative orientation of their fragments and the newly forming CC bond distance, and exhibit only minor deviations from the structures of the reactants. Both reaction pathways are concerted and asynchronous, but the [1+2] reaction has a greater degree of asynchronicity. Examination of the frontier molecular orbitals reveals that both the [3+2] and [1+2] barrier heights are related to two sets of orbital interactions, with the interaction between the lowest unoccupied molecular orbital π [Formula: see text] of nitrilimine and the highest occupied molecular orbital of ethene in common. The second interaction in both cases is carbene-like. A relationship between the weights of the 1,3-dipolar resonance contribution in the various nitrilimines and the corresponding [3+2] barrier heights was not found, but a good correlation could be found between the [1+2] barrier heights and both the 1,3-dipolar and carbene contributions. Inspection of the potential energy surface in the vicinity of the two transition states for the reaction between unsubstituted nitrilimine and ethene suggests that the observed [3+2] product is a result of an initial carbene-like approach of the two fragments followed by a ridge bifurcation that leads to the [3+2] product minimum. Key words: nitrilimines, 1,3-dipole, carbene, [3+2] cycloaddition, [1+2] cycloaddition, density functional theory (DFT).
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Cherifi, Yacine, Ahcène Chaouchi, Yannick Lorgoilloux, Mohammed Rguiti, Abdelaziz Kadri y Christian Courtois. "Electrical, dielectric and photocatalytic properties of Fe-doped ZnO nanomaterials synthesized by sol gel method". Processing and Application of Ceramics 10, n.º 3 (2016): 125–35. http://dx.doi.org/10.2298/pac1603125c.
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Fe-doped ZnO nanoparticles were synthesized by sol gel technique. Fine-scale and single phase hexagonal wurtzite structure in all samples were confirmed by SEM and XRD, respectively. The band gap energy depends on the amount of Fe and was found to be in the range of 3.11-2.53 eV. The electric and dielectric properties were investigated using complex impedance spectroscopy. AC conductivity data were correlated with the barrier hopping (CBH) model to evaluate the binding energy (Wm), the minimum hopping distance (Rmin) and the density of states at Fermi level, N(EF). Fe doping in ZnO also improved the photocatalytic activity. Thus, the sample Zn0.95Fe0.05O showed high degradation potential towards methylene blue (MB), i.e. it degrades 90% of BM in 90min under UV light.
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Muratov, Temur T. "Statistical approach to the process of tunnel ionisation of impurity centres near the heterointerface". Kondensirovannye sredy i mezhfaznye granitsy = Condensed Matter and Interphases 23, n.º 4 (24 de noviembre de 2021): 529–34. http://dx.doi.org/10.17308/kcmf.2021.23/3671.
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To date, the processes of tunnel ionisation of impurities near the interface between two different semiconductors have been comprehensively studied. The most important parameters of the contact electron states of impurities have been determined. However, the calculated expressions for these parameters have been of local nature, as applied to individual impurities. Meanwhile, it is easy to understand that a number of processes, such as the flow of charge carriers and their diffusion through a heterojunction, are clearly statistical in nature. The same applies to the processes of tunnel ionisation of shallow and/or deep impurities near the interface. A statistical approach to the calculation of the parameters of tunnel ionisation of impurities broadens the opportunities for obtaining fundamental information regarding surface electronstates.The aim of this work was to use a statistical approach to study the effect of the heterointerface on the energy spectrum of shallow and deep centres. For this purpose, the expansion of the reflected quasi-classical wave function within the complete system of spherical harmonics and the subsequent extraction of the zero harmonic amplitude (s-component) was used to estimate the minimum distance from the impurity to the heterobarrier and to specify the limitations of the applicability of the results obtained in other works. The article analyses the conditions of the quasi-classical approximation which are used to estimate the order of the value for the minimum height of the potential barrier (pit).This work (with due consideration given to the minimum distance estimate) presents averaged formulas obtained for the energy shift of the ground state and the lifetime of the quasi-stationary state depending on the distance from the heterobarrier. Some qualitatively new considerations can also be found in the article. The distribution of impurity centres near the heterobarrier is assumed to be uniform. The article discusses the role of electron transitions in causing the buffer field effect for both shallow and deep centres. The focus of the article is on the estimates of various physical parameters characterising electron transitions near the heterobarrier.
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Rifai, Isnan Nur, Tri Ratnoto y Subari Subari. "Microlidar Application for Object Detector to Support The Navigation System in Self-Driving Vehicle". INFORMAL: Informatics Journal 8, n.º 3 (3 de enero de 2024): 243. http://dx.doi.org/10.19184/isj.v8i3.44188.
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The ability to detect and measure the distance of potential obstacles is importance for navigation system in self-driving vehicles. The measurement process needs to be fast and accurate since the controller requires real-time data to make quick decisions and respond to any potential disturbances on the vehicle's track. This research aims to develop Microlidar for detection system that can accurately measure the distance of a potential obstacle object. The Microlidar utilize Lidar Lite V3 proximity sensor which have range measurement specification of up to 40 meter. Microlidar rapidly rotate 360 degrees by using a stepper motor while in the same time continuously measure the real-time distance. The measurement data are sent to a microcontroller through I2C, and the Processing software plot the 2D image which work like radar visualization. The system is assessed for ranging the various distance object in static and dynamic measurement mode. The results show that the Microlidar has a good level of accuracy with an average error value at the distance of 300 cm is 4.99 cm or 1.7% while the average error value at the distance of 1000 cm is 15.69 cm or 1.6% obtained from 100 data sets collected. The communication from the sensor to Arduino requires a minimum baud rate of 115200 bits/second to minimize data loss and ensure that the measured distance can be processed in real time by the microcontroller. Real-time data with high speed is essential since it will be used on the vehicle in order to quickly decide whether there is a barrier or not on the vehicle’s track. The sensor analysis distance expected from this research could be used as a reference to support the navigation system performance of self-driving vehicles.
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Saidi, M., A. Chaouchi, S. D'Astorg, M. Rguiti y C. Courtois. "Dielectric, ferroelectrics properties and impedance spectroscopy analysis of the [(Na0.535K0.480)0.966Li0.058](Nb0.90Ta0.10)O3-based lead-free ceramics". Journal of Advanced Dielectrics 05, n.º 01 (marzo de 2015): 1550007. http://dx.doi.org/10.1142/s2010135x15500071.
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Polycrystalline of [( Na 0.535 K 0.480)0.966 Li 0.058] (Nb 0.90 Ta 0.10) O 3 samples were prepared using the high-temperature solid-state reaction technique. X-ray diffraction (XRD) analysis indicates the formation of a single-phase with orthorhombic structure. AC impedance plots were used as tool to analyze the electrical behavior of the sample as a function of frequency at different temperatures. The AC impedance studies revealed the presence of grain effect, from 425°C onwards. Complex impedance analysis indicated non-Debye type dielectric relaxation. The Nyquist plot showed the negative temperature coefficient of resistance (NTCR) characteristic of NKLNT. The AC conductivity results were used to correlate with the barrier hopping (CBH) model to evaluate the binding energy (Wm), the minimum hopping distance (R min ), the density of states at Fermi level (N(Ef)), and the activation energy of the compound.
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Rossi Fernández, Ana C., Nicolás F. Domancich, Ricardo M. Ferullo y Norberto J. Castellani. "Aluminum adsorption on graphene: Theoretical study of dispersion effects". Journal of Theoretical and Computational Chemistry 18, n.º 04 (junio de 2019): 1950019. http://dx.doi.org/10.1142/s0219633619500196.
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The interaction between a single atom and graphene is an example in which the density functional theory (DFT) presents serious difficulties in giving an appropriate description of the adsorbate–substrate interaction, giving also different predictions according to the chosen approximation. The present calculations sustain that the inclusion of dispersion interactions in the framework of DFT for the Al/graphene system lead to potential energy curves of different nature according to the theoretical approach employed. The adsorption of an Al atom on the graphene surface was studied using both cluster and slab models. Cluster DFT–PBE calculations show the presence of a minimum at hollow site at an Al–graphene distance of about 2.1–2.3 Å corresponding to an exothermic state. Conversely, under B3LYP the same adsorption mode is endothermic. In comparison, our MP2 reference calculations predict the formation of two minima, both of exothermic nature, separated by an important energy barrier (about 0.2–0.4[Formula: see text]eV). The incorporation of empirical van der Walls (vdW) corrections to B3LYP changes the original behavior, giving an exothermic adsorption; furthermore, it produces a second, more external minimum. Slab calculations with PBE, and specially using the vdW-DF2 functional, predict also the formation of a minimum of very low depth at about 3.1 Å. The analysis of results obtained with cluster and slab models sustains that the bonding of the inner minima is of ionic character while that of the external ones is of dispersion character.
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Smirnova, Yuliya G., Herre Jelger Risselada y Marcus Müller. "Thermodynamically reversible paths of the first fusion intermediate reveal an important role for membrane anchors of fusion proteins". Proceedings of the National Academy of Sciences 116, n.º 7 (30 de enero de 2019): 2571–76. http://dx.doi.org/10.1073/pnas.1818200116.
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Biological membrane fusion proceeds via an essential topological transition of the two membranes involved. Known players such as certain lipid species and fusion proteins are generally believed to alter the free energy and thus the rate of the fusion reaction. Quantifying these effects by theory poses a major challenge since the essential reaction intermediates are collective, diffusive and of a molecular length scale. We conducted molecular dynamics simulations in conjunction with a state-of-the-art string method to resolve the minimum free-energy path of the first fusion intermediate state, the so-called stalk. We demonstrate that the isolated transmembrane domains (TMDs) of fusion proteins such as SNARE molecules drastically lower the free energy of both the stalk barrier and metastable stalk, which is not trivially explained by molecular shape arguments. We relate this effect to the local thinning of the membrane (negative hydrophobic mismatch) imposed by the TMDs which favors the nearby presence of the highly bent stalk structure or prestalk dimple. The distance between the membranes is the most crucial determinant of the free energy of the stalk, whereas the free-energy barrier changes only slightly. Surprisingly, fusion enhancing lipids, i.e., lipids with a negative spontaneous curvature, such as PE lipids have little effect on the free energy of the stalk barrier, likely because of its single molecular nature. In contrast, the lipid shape plays a crucial role in overcoming the hydration repulsion between two membranes and thus rather lowers the total work required to form a stalk.
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Ridenour, Marcella V. "Age, Side Height, and Spindle Shape of the Crib in Climbing over the Side". Perceptual and Motor Skills 85, n.º 2 (octubre de 1997): 667–74. http://dx.doi.org/10.2466/pms.1997.85.2.667.
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The crib is the only infant product in which a consumer, such as a parent or caretaker, is encouraged to leave the infant unattended, usually alone in the bedroom, while the infant is sleeping or going to sleep or waking. Given frequent falls from the crib, federal crib regulations have set the minimum distance between the top of the mattress support and cop of the crib side rail as 26 in. and this height must include a 6-in. thick mattress. When a mattress is used with the crib, the actual height of the crib side as a barrier is 20 in. These crib regulations also require instructions for the caretaker to discontinue using the crib when the child's height is 35 inches. These federal crib regulations attempt to create an escape-resistant sleeping environment for all children who are less than 35 in. tall. Of 144 children between the ages of 12.5 and 36.5 mo. observed while attempting to climb out of a crib, who also had standing heights of less than 35 in., many were able to climb from cribs with side rail heights of 26 in. When the crib side-rail height was raised beyond the minimum of 26 in., the frequency of children climbing over the crib rails decreased.
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Chmielewska-Muciek, Dorota. "Polish Emigrants on Organizational Culture of Austrian Companies". Management 22, n.º 2 (1 de diciembre de 2018): 249–63. http://dx.doi.org/10.2478/manment-2018-0035.
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Summary The paper is of theoretical and empirical character. It outlines considerations and studies pertaining to the perception of organizational culture of Austrian companies by Polish emigrants. When undertaking employment abroad, emigrants face a challenge of adapting to a new environment. The adaptation pertains to several aspects. Organizational culture is one of these. Therefore, the following research problem arises: What is the organizational culture of Austrian enterprises like?, and, Do emigrants experience problems with the cultural adaptation? Interviews with 40 Poles who worked a minimum of 5 years in Austria were conducted. The interviews revealed that respondents believed the organizational culture of Austrian companies was characterized by low power distance, individualism, activity, and status based upon achievements. The straightforward analysis was difficult to be made with regard to several values. This is true for low vs. high uncertainty tolerance, people vs. task focus, and focus on the outside vs. inside. The identified organizational culture of Austrian enterprises did not pose a significant barrier for respondents.
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Chen, Jen-San y Chun-Yi Liao. "Experiment and Analysis on the Free Dynamics of a Shallow Arch After an Impact Load at the End". Journal of Applied Mechanics 72, n.º 1 (1 de enero de 2005): 54–61. http://dx.doi.org/10.1115/1.1827245.
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In this paper we consider a sinusoidal arch with one end pinned in space while the other end attached to a mass and supported by a spring. The supporting wall of the spring is moved a distance quasi-statically to initiate preload in the arch and the spring. The assembly is then set in motion by an impact at the attached mass. The condition under which the arch may snap to the other side dynamically depends on the initial speed of the attached mass due to impact. Sufficient condition on the initial speed against dynamic snap-through is formulated based on the concept of minimum energy barrier. The effects of damping on the transient response of the assembly are also discussed. An experimental setup is designed to measure the transient response of the arch following the impact and the critical initial speed of the attached mass. The experimental results are in good agreement with theoretical predictions.
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Hidayanto, Ari y Heru Winarno. "PROTOTIPE SISTEM AUTOBRAKE PADA MOBIL MENGGUNAKAN SENSOR JARAK ULTRASONIK HC-SR04 BERBASIS ARDUINO MEGA 2560". Gema Teknologi 18, n.º 4 (30 de abril de 2016): 29. http://dx.doi.org/10.14710/gt.v18i4.21913.
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Ari Hidayanto, Heru Winarno in this paper explain that The high number of traffic accidents is currently a factor in the driver's error in driving (human error). One of the accidents that often occur include car accidents. Of the several incidents that have occurred, the average accident occurred because of the driver's lack of concentration in driving his car. This resulted in the driver not being able to control the speed of the vehicle immediately when there was a sudden object in front, moreover this happened when the vehicle drove at high speed. To avoid this, when driving, it really needs a vehicle security system that also greatly affects the driver's safety. With the development of existing science and technology allows humans to make security systems in motorized vehicles. Accidents due to driver negligence can be overcome by making the braking system automatic then the vehicle speed will slow down and carry out mechanical braking (disc brake) automatically based on the minimum distance of the car with the barrier even though the driver does not pull the brake lever. Realizing this, an autobrake system (automatic braking) was designed based on the distance of the car with the barrier using the HC-SR04 ultrasonic distance sensor. When between a sensor and a barrier at a distance of <= 70 cm, the central lock actuator will go forward and press the disc brake lever. System notifications will be displayed via 20X4 LCD, LED and Buzzer. The system work will be controlled by Arduino Mega 2560. Keywords: Autobrake, Disc Brake, Ultrasonic sensor HC-SR04, Central Lock, LCD 20x4, Arduino Mega 2560ReferencesAgus Setya Abadi, Delta. 2008. Sensor Ultrasonic Sebagai Alat Navigasi Robot Pemadam Api. Tugas Akhir PSD III Teknik Elektro (tidak diterbitkan). Semarang: Universitas Diponegoro.Bishop, Owen. 2004. Dasar-Dasar Elekrtonika. Jakarta: Penerbit Erlangga.Cahyo Saputro, Adi. 2014. Central Door Lock. Diunduh dari http://otomotifmaju.blogspot.com/2014/08/sentral-door-lock.html, pada 17 Juni 2015 pukul 21.46 WIB.Chan, Yefri. 2010. Teori Dasar Rem. Buku Panduan Teknik Mesin (tidak diterbitkan). Jakarta Timur: Universitas Darma Persada.Putu Giovani. I. 2014. Merancang Driver Motor DC. Diunduh dari http://www.geyosoft.com/2014/merancang-driver-motor-dc, pada 17 Juni 2015 pukul 08.00 WIB.Prayogo, Rudito. 2012. Pengaturan PWM dengan PLC. Tugas Mata Kuliah Teknik Otomasi (tidak diterbitkan). Malang: Universitas Brawijaya.Roghib, Rokhman, dan M. Qomarruzzaman. 2014. Introduction Arduino Training Kit. Yogyakarta: House Of Technology.Sandi. 2014. Acccumulator Atau Aki. Diunduh dari http://www.sandielektronik.com/2014/03/accumulator-atau-aki.html, pada 30 Mei 2015 pukul 16.15 WIB.Setyadi, Ary. 2010. Bahasa Indonesia Dalam Karya Ilmiah. Semarang: Fakultas Ilmu Budaya Undip.Sulistyowati, Riny. 2012. Perancangan Prototype System Kontrol Dan Monitoring Pembatas Daya Listrik Berbasis Mikrokontroler. Tugas Akhir Teknik Elektro (tidak diterbitkan). Surabaya: Institut Adhi Tama Surabaya.Tooley, Mike. 2003. Rangkainan Elektronik Prinsip dan Aplikasi Edisi Kedua. Jakarta: Penerbit Erlangga.
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Andrino, Caroline Oliveira, Rafael Gomes Barbosa-Silva, Juliana Lovo, Pedro Lage Viana, Marcelo Freire Moro y Daniela Cristina Zappi. "Iron islands in the Amazon: investigating plant beta diversity of canga outcrops". PhytoKeys 165 (28 de octubre de 2020): 1–25. http://dx.doi.org/10.3897/phytokeys.165.54819.
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The world’s largest mineral iron province, Serra dos Carajás, is home to an open vegetation known as canga, found on top of isolated outcrops rising out of the Amazon rainforest. Over one thousand vascular plants species have been recorded in these canga sites, including 38 edaphic endemics. A new survey adds to our investigation of biogeographic relationships between sixteen canga outcrops and the effect of the distance between site pairs on the number of shared species, regional species turnover and species distribution patterns. Plant collecting expeditions to the westernmost site, the Serra de Campos of São Félix do Xingu (SFX), were carried out followed by the identification of all collected specimens and the creation of a species database, built to perform biogeographical analyses. Floristic relationships among the sites were investigated regarding their similarity, using multivariate analyses. The correlation between canga areas and species richness was tested, as well as the geographical distance between pairs of outcrops and their shared species. Vascular plants at SFX total 254 species including 17 edaphic endemics. All canga sites are grouped with 25% of minimum similarity, and the SFX falls within a large subgroup of outcrops. The total species number shared between site pairs does not change significantly with geographical distance but is positively correlated with the area of each outcrop. Meanwhile, shared endemic species numbers between site pairs decline when geographical distance increases, possibly imposed by the barrier of the rainforest. Our data suggest higher shared similarity between the largest and species-richest sites as opposed to geographically nearby sites, and provide useful insight for drafting conservation and compensation measures for canga locations. The size of the canga outcrops is associated to higher floristic diversity but connectivity among islands also plays a role in their similarity.
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Hadiza Gambo Rimi, Emmanuel Joseph, Dimas Skam Joseph y Dlama Zira Joseph. "Evaluation of shielding thickness in the radio-diagnostic facility of Turai Yaradua Maternity and Children Hospital Katsina, Katsina State, Nigeria". International Journal of Science and Research Archive 9, n.º 2 (30 de julio de 2023): 156–62. http://dx.doi.org/10.30574/ijsra.2023.9.2.0529.
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The medical application of radiation can induce radio-biological effects which makes it necessary to ensure some safety precautions, of which, room shielding is one of those safety measures. The aim of this study was to assess the lead wall lining thickness of the radio-diagnostic room of Turai Yaradua Maternity and Children Hospital Katsina. The required lead wall lining thickness was estimated using NCRP 147 formulations. The measured area of the radio-diagnostic room was 39.44 m2. The maximum required lead thickness values were estimated as 1.1 mm and 0.8 mm for erect and supine radiographic positions, respectively, while, the installed lead wall lining thickness was 2 mm. The area monitoring revealed that there was no leakage radiation. Though, the shielding was adequate and there was no leakage radiation, it is however recommended that the radiation workers maintain maximum distance, minimum exposure time and use shielding barrier in order to ensure minimal occupational radiation exposure. Periodic area monitoring is also encouraged in order to prevent radiation exposure of the members of the public.
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Wardhani, Diana Kusuma y Jojok Mukono Mukono. "Sensorineural Hearing Loss Due to Exposure of Noisy Trains on Populations Around Turirejo Train Railroad Cross". JURNAL KESEHATAN LINGKUNGAN 12, n.º 1 (30 de enero de 2020): 59. http://dx.doi.org/10.20473/jkl.v12i1.2020.59-68.
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Introduction: As one of the preferred modes of land transportation, the frequency of train services was very high. One of the negative impacts arising from train activity was noise. The high noise intensity of the train causes hearing loss. Method: This study aims to analyze the differences in the incidence of hearing loss in 2 groups of residents in Turirejo Lawang Malang. This research used the observational method and the data were analyzed descriptive qualitative. A total of 20 people were selected as respondents by purposive sampling. Noise intensity was measured by Sound Level Meter and audiometric measurements were examined at SIMA Malang Laboratory. Result and Discussion: The prevalence of sensorineural hearing loss was more common in residents whose homes at 3-7 m away from the railroad tracks. In addition, residents who lived at least 15 years at a distance of 3-7 m also experienced more hearing loss. One cause of hearing loss is due to exposure to high noise and for a long time and will damage the hair cells in the cochlea, causing hearing loss. If noise exposure continues and for a long period of time damage to hair cells will be permanent and cannot return to normal. Conclusion: There needs to be a policy from the government in determining the minimum limit of the distance of the house to the railroad tracks. In addition, it is necessary to install a barrier near people’s homes to reduce noise.
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Lee, One-Sun. "Dynamic Properties of Water Confined in Graphene-Based Membrane: A Classical Molecular Dynamics Simulation Study". Membranes 9, n.º 12 (4 de diciembre de 2019): 165. http://dx.doi.org/10.3390/membranes9120165.
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We performed molecular dynamics simulations of water molecules inside a hydrophobic membrane composed of stacked graphene sheets. By decreasing the density of water molecules inside the membrane, we observed that water molecules form a droplet through a hydrogen bond with each other in the hydrophobic environment that stacked graphene sheets create. We found that the water droplet translates as a whole body rather than a dissipate. The translational diffusion coefficient along the graphene surface increases as the number of water molecules in the droplet decreases, because the bigger water droplet has a stronger van der Waals interaction with the graphene surface that hampers the translational motion. We also observed a longer hydrogen bond lifetime as the density of water decreased, because the hydrophobic environment limits the libration motion of the water molecules. We also calculated the reorientational correlation time of the water molecules, and we found that the rotational motion of confined water inside the membrane is anisotropic and the reorientational correlation time of confined water is slower than that of bulk water. In addition, we employed steered molecular dynamics simulations for guiding the target molecule, and measured the free energy profile of water and ion penetration through the interstice between graphene sheets. The free energy profile of penetration revealed that the optimum interlayer distance for desalination is ~10 Å, where the minimum distance for water penetration is 7 Å. With a 7 Å interlayer distance between the graphene sheets, water molecules are stabilized inside the interlayer space because of the van der Waals interaction with the graphene sheets where sodium and chloride ions suffer from a 3–8 kcal/mol energy barrier for penetration. We believe that our simulation results would be a significant contribution for designing a new graphene-based membrane for desalination.
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Ugarte, Ricardo, Guillermo Salgado y Luis Basáez. "A theoretical study of the nitration of eugenol with the nitronium ion". Collection of Czechoslovak Chemical Communications 76, n.º 12 (2011): 1529–48. http://dx.doi.org/10.1135/cccc2011156.
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The nitration of eugenol was investigated by using density functional theory (DFT) calculations. Potential energy surface and molecular electrostatic potential of eugenol was constructed in order to find, respectively, the minimum energy conformers and the possible sites for electrophilic attack. Stationary points were located and characterized at the B3LYP/6-311++G(2d,2p) level of theory. A strongly bound π-complex was found, in which the distance between the nitrogen atom of the NO2 moiety and the C1 carbon atom of the aromatic ring is 2.15 Å in the gas phase and 2.06 Å in dichloromethane. The most favorable σ-complex or Wheland intermediate is the result from the interaction between the nitrogen and the C6 ring carbon atom. The transition state that connects both complexes is more resembling the σ-complex. The nitronium ion exothermically reacts with eugenol to give the π-complex without an energy barrier. The next stage of the reaction pathway, π-complex → σ-complex, is endothermic and involves a Gibbs energy of activation of 7.9–8.0 kcal mol–1 (gas phase) and 8.3–8.9 kcal mol–1 (CH2Cl2).
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Yu, Yan-Zi, Jian-Gang Guo y Yi-Lan Kang. "An Analytical Model for Adsorption and Diffusion of Atoms/Ions on Graphene Surface". Journal of Nanomaterials 2015 (2015): 1–10. http://dx.doi.org/10.1155/2015/382474.
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Theoretical investigations are made on adsorption and diffusion of atoms/ions on graphene surface based on an analytical continuous model. An atom/ion interacts with every carbon atom of graphene through a pairwise potential which can be approximated by the Lennard-Jones (L-J) potential. Using the Fourier expansion of the interaction potential, the total interaction energy between the adsorption atom/ion and a monolayer graphene is derived. The energy-distance relationships in the normal and lateral directions for varied atoms/ions, including gold atom (Au), platinum atom (Pt), manganese ion (Mn2+), sodium ion (Na1+), and lithium-ion (Li1+), on monolayer graphene surface are analyzed. The equilibrium position and binding energy of the atoms/ions at three particular adsorption sites (hollow, bridge, and top) are calculated, and the adsorption stability is discussed. The results show that H-site is the most stable adsorption site, which is in agreement with the results of other literatures. What is more, the periodic interaction energy and interaction forces of lithium-ion diffusing along specific paths on graphene surface are also obtained and analyzed. The minimum energy barrier for diffusion is calculated. The possible applications of present study include drug delivery system (DDS), atomic scale friction, rechargeable lithium-ion graphene battery, and energy storage in carbon materials.
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Ngoprasert, Dusit, Antony J. Lynam y George A. Gale. "Human disturbance affects habitat use and behaviour of Asiatic leopard Panthera pardus in Kaeng Krachan National Park, Thailand". Oryx 41, n.º 3 (julio de 2007): 343–51. http://dx.doi.org/10.1017/s0030605307001102.
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AbstractEdge effects arising from road construction and other development in protected areas can negatively affect the behaviour of wildlife, particularly large carnivores. The Asiatic leopard Panthera pardus is a large carnivore that may be sensitive to edge effects. Camera trapping was used to assess the influence of human disturbance along forest edges on leopard behaviour and habitat use in a 104 km2 area of Kaeng Krachan National Park, Thailand. A minimum of four male and two female leopards was recorded in the study area. A Park access road bisecting the study area was not a barrier to leopard movement but movements and activity were affected by human traffic inside the Park. A regression model showed that leopard habitat use increased with distance from human settlements at the forest edge. As in other parts of its range, leopards at Kaeng Krachan National Park tended to show less diurnal activity in areas more heavily used by people compared to areas less used. As is the case with tigers, such responses may pose a threat to leopard population persistence but more research is needed to determine the demographic implications of edge effects for Asiatic leopards and other large tropical carnivores, and the appropriate mitigation strategies required.
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Li, Chunbao y Bo Yang. "Robust Scale Adaptive Visual Tracking with Correlation Filters". Applied Sciences 8, n.º 11 (24 de octubre de 2018): 2037. http://dx.doi.org/10.3390/app8112037.
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Visual tracking is a challenging task in computer vision due to various appearance changes of the target object. In recent years, correlation filter plays an important role in visual tracking and many state-of-the-art correlation filter based trackers are proposed in the literature. However, these trackers still have certain limitations. Most of existing trackers cannot well deal with scale variation, and they may easily drift to the background in the case of occlusion. To overcome the above problems, we propose a Correlation Filters based Scale Adaptive (CFSA) visual tracker. In the tracker, a modified EdgeBoxes generator, is proposed to generate high-quality candidate object proposals for tracking. The pool of generated candidate object proposals is adopted to estimate the position of the target object using a kernelized correlation filter based tracker with HOG and color naming features. In order to deal with changes in target scale, a scale estimation method is proposed by combining the water flow driven MBD (minimum barrier distance) algorithm with the estimated position. Furthermore, an online updating schema is adopted to reduce the interference of the surrounding background. Experimental results on two large benchmark datasets demonstrate that the CFSA tracker achieves favorable performance compared with the state-of-the-art trackers.
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Strandberg, Roine, Raymond H. G. Klaassen, Mikael Hake, Patrik Olofsson y Thomas Alerstam. "Converging migration routes of Eurasian hobbies Falco subbuteo crossing the African equatorial rain forest". Proceedings of the Royal Society B: Biological Sciences 276, n.º 1657 (4 de noviembre de 2008): 727–33. http://dx.doi.org/10.1098/rspb.2008.1202.
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Autumn migration of adult Eurasian hobbies Falco subbuteo from Europe to southern Africa was recorded by satellite telemetry and observed routes were compared with randomly simulated routes. Two non-random features of observed routes were revealed: (i) shifts to more westerly longitudes than straight paths to destinations and (ii) strong route convergence towards a restricted area close to the equator (1° S, 15° E). The birds migrated south or southwest to approximately 10° N, where they changed to south-easterly courses. The maximal spread between routes at 10° N (2134 km) rapidly decreased to a minimum (67 km) close to the equator. We found a striking relationship between the route convergence and the distribution of continuous rainforest, suggesting that hobbies minimize flight distance across the forest, concentrating in a corridor where habitat may be more suitable for travelling and foraging. With rainforest forming a possible ecological barrier, many migrants may cross the equator either at 15° E, similar to the hobbies, or at 30–40° E, east of the rainforest where large-scale migration is well documented. Much remains to be understood about the role of the rainforest for the evolution and future of the trans-equatorial Palaearctic-African bird migration systems.
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Stepanovich, I. M. y Y. S. Shavalda. "Advanced methodology of ecological and geobotanical research of roadside vegetation". Proceedings of the National Academy of Sciences of Belarus, Biological Series 67, n.º 4 (1 de noviembre de 2022): 374–85. http://dx.doi.org/10.29235/1029-8940-2022-67-4-374-385.
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The possibilities of the method of ecological-phytocenotic profiles in the study of roadside vegetation are tracked. Its advantages are noted: it increases the representativeness of geobotanical relevés, allows to make an objective comparative analysis of the state of phytocenoses, their components, ecotopes in spatiotemporal relationship.Ecological and phytocenological studies carried out along roads and railways show, firstly, the regional features of flora, and secondly, the specifics of the ecosystem belonging of species and phytocenoses. The degree of synanthropization of vegetation in all exposures (“notch”, “zero mark” and “mound”) naturally decreases from extremely high near the road to the minimum at a distance of 50 m or more from the road path. At the same time the highest rates and the sharpest decrease in synanthropization are observed in the “mound” exposition in closed floodplain and swampy ecosystems, as well as in the “notch” exposition in the forest ecosystem. These changes in the forest ecosystem are somewhat lower in the expositions “mound” and “zero mark”. Forest acts as a barrier. The amplitude of the distribution of anthropophytes along the profile is generally small in open meadows and in agroecosystems. The impact of mound slopes, the direction of roads and railways on the intensity of synanthropization of vegetation, including the penetration of invasive species, was found.
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Krebsbach, M., C. Schiller, D. Brunner, G. Günther, M. I. Hegglin, D. Mottaghy, M. Riese, N. Spelten y H. Wernli. "Seasonal cycles and variability of O<sub>3</sub> and H<sub>2</sub>O in the UT/LMS during SPURT". Atmospheric Chemistry and Physics 6, n.º 1 (24 de enero de 2006): 109–25. http://dx.doi.org/10.5194/acp-6-109-2006.
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Abstract. Airborne high resolution in situ measurements of a large set of trace gases including ozone (O3) and total water (H2O) in the upper troposphere and the lowermost stratosphere (UT/LMS) have been performed above Europe within the SPURT project. SPURT provides an extensive data coverage of the UT/LMS in each season within the time period between November 2001 and July 2003. In the LMS a distinct spring maximum and autumn minimum is observed in O3, whereas its annual cycle in the UT is shifted by 2–3 months later towards the end of the year. The more variable H2O measurements reveal a maximum during summer and a minimum during autumn/winter with no phase shift between the two atmospheric compartments. For a comprehensive insight into trace gas composition and variability in the UT/LMS several statistical methods are applied using chemical, thermal and dynamical vertical coordinates. In particular, 2-dimensional probability distribution functions serve as a tool to transform localised aircraft data to a more comprehensive view of the probed atmospheric region. It appears that both trace gases, O3 and H2O, reveal the most compact arrangement and are best correlated in the view of potential vorticity (PV) and distance to the local tropopause, indicating an advanced mixing state on these surfaces. Thus, strong gradients of PV seem to act as a transport barrier both in the vertical and the horizontal direction. The alignment of trace gas isopleths reflects the existence of a year-round extra-tropical tropopause transition layer. The SPURT measurements reveal that this layer is mainly affected by stratospheric air during winter/spring and by tropospheric air during autumn/summer. Normalised mixing entropy values for O3 and H2O in the LMS appear to be maximal during spring and summer, respectively, indicating highest variability of these trace gases during the respective seasons.
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Ahmad, Mahmood, Arshad Jamal, Xiao-Wei Tang, Mohammed A. Al-Sughaiyer, Hassan M. Al-Ahmadi y Feezan Ahmad. "Assessing Potable Water Quality and Identifying Areas of Waterborne Diarrheal and Fluorosis Health Risks Using Spatial Interpolation in Peshawar, Pakistan". Water 12, n.º 8 (31 de julio de 2020): 2163. http://dx.doi.org/10.3390/w12082163.
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Waterborne diseases have become one of the major public health concerns worldwide. This study is aimed to investigate and develop spatial distribution mapping of the potable water quality parameters in the city of Peshawar, Pakistan. A total of 108 water samples collected across the entire study area were subjected to physio-chemical and biological analyses. Tested parameters included pH, turbidity, temperature, fluoride concentration levels, and bacterial counts (faecal coliforms). Inverse distance weighting (IDW) interpolation in geographic information systems (GIS) was used for spatial analysis. Test results revealed that 48% of water samples had faecal coliforms count (per 100 mL) greater than World Health Organization (WHO) minimum limits, while 31% of samples had fluoride concentrations in excess of the WHO maximum guide values. Spatial distribution mapping was developed for faecal coliforms count and fluoride ion concentration using ArcGIS to highlight the high-risk settlements in the study area. Results showed that around 20% area under faecal coliforms and approximately 33% area based on fluoride concentrations fall under the need for treatment category. The pH and turbidity were found in compliance with WHO desirable limits. The sanitary inspection score significantly depicted that ineffective multi-barrier approaches consequently deteriorated the water quality at the consumer’s end. Findings from the present study shall be useful to policymakers for adopting necessary remedial measures before it severely affects public health.
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McMillan, Alexander H., Emma K. Thomée, Alessandra Dellaquila, Hussam Nassman, Tatiana Segura y Sasha Cai Lesher-Pérez. "Rapid Fabrication of Membrane-Integrated Thermoplastic Elastomer Microfluidic Devices". Micromachines 11, n.º 8 (28 de julio de 2020): 731. http://dx.doi.org/10.3390/mi11080731.
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Leveraging the advantageous material properties of recently developed soft thermoplastic elastomer materials, this work presents the facile and rapid fabrication of composite membrane-integrated microfluidic devices consisting of FlexdymTM polymer and commercially available porous polycarbonate membranes. The three-layer devices can be fabricated in under 2.5 h, consisting of a 2-min hot embossing cycle, conformal contact between device layers and a low-temperature baking step. The strength of the FlexdymTM-polycarbonate seal was characterized using a specialized microfluidic delamination device and an automated pressure controller configuration, offering a standardized and high-throughput method of microfluidic burst testing. Given a minimum bonding distance of 200 μm, the materials showed bonding that reliably withstood pressures of 500 mbar and above, which is sufficient for most microfluidic cell culture applications. Bonding was also stable when subjected to long term pressurization (10 h) and repeated use (10,000 pressure cycles). Cell culture trials confirmed good cell adhesion and sustained culture of human dermal fibroblasts on a polycarbonate membrane inside the device channels over the course of one week. In comparison to existing porous membrane-based microfluidic platforms of this configuration, most often made of polydimethylsiloxane (PDMS), these devices offer a streamlined fabrication methodology with materials having favourable properties for cell culture applications and the potential for implementation in barrier model organ-on-chips.
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Butler, LG y GM Head. "Photoperiodic rhythm of wool growth and its contribution to seasonal wool production by the Merino, Polwarth, and their reciprocal crosses in southern Australia". Australian Journal of Experimental Agriculture 34, n.º 3 (1994): 311. http://dx.doi.org/10.1071/ea9940311.
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Twelve wethers of each of the Merino and Polwarth breeds and their reciprocal crosses were fed at1 of 2 levels in individual pens for 14 months. Periodic clean wool weight, yield, fibre diameter, and the coefficient of variation (CV%) for fibre diameter were measured from midside patches harvested every6 weeks.There was a significant effect of time of wool harvest on clean wool weight per cm2, yield, fibre diameter(all P<0.01), and its CV% (P<0.05). A trough in wool production occurred about August-September and a peak in January. The amplitude of the photoperiodic rhythm of wool growth (difference between maximum and minimum wool growth per cm2 per 42 days as a percentage of the average) was 40%. Yield also displayed a substantial photoperiodic rhythm, but that of fibre diameter was less pronounced. Mean staple strength was 32.3 N/ktex, the mean break occurring at a distance of 60% of the staple length from the tip; there was no effect of genotype or level of feeding. From comparison with published Tasmanian field data, the seasonal wool growth pattern of sheep at pasture appears similar to the photoperiodic rhythm but occurs about a month earlier. It was concluded that the photoperiodic rhythm of wool production of Tasmanian Merino-based breeds should not be a barrier to manipulation of wool quality (staple strength and fibre diameter) by nutritional management.
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Pymer, Sean, Amy Harwood, Said Ibeggazene, Gordon McGregor, Chao Huang, Maureen Twiddy, Adam R. Nicholls et al. "High INtensity Interval Training In pATiEnts with intermittent claudication (INITIATE): protocol for a multicentre, proof-of-concept, prospective interventional study". BMJ Open 10, n.º 7 (julio de 2020): e038825. http://dx.doi.org/10.1136/bmjopen-2020-038825.
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IntroductionThe first-line recommended treatment for patients with intermittent claudication (IC) is a supervised exercise programme (SEP), which includes a minimum of 2-hours of exercise per week over a 12-week period. However, provision, uptake and adherence rates for these SEP programmes are poor, with time constraints cited as a common participant barrier. High-intensity interval training (HIIT) is more time-efficient and therefore has the potential to overcome this barrier. However, evidence is lacking for the role of HIIT in those with IC. This proof-of-concept study aims to consider the safety, feasibility, tolerability and acceptability of a HIIT programme for patients with IC.Methods and analysisThis multicentre, single-group, prospective, interventional feasibility study will recruit 40 patients with IC, who will complete 6 weeks of HIIT, 3 times a week. HIIT will involve a supervised programme of 10×1 min high-intensity cycling intervals at 85%–90% peak power output (PPO), interspaced with 10×1 min low intensity intervals at 20%–25% PPO. PPO will be determined from a baseline cardiopulmonary exercise test (CPET) and it is intended that patients will achieve ≥85% of maximum heart rate from CPET, by the end of the second HIIT interval. Primary outcome measures are safety (occurrence of adverse events directly related to the study), programme feasibility (including participant eligibility, recruitment and completion rates) and HIIT tolerability (ability to achieve and maintain the required intensity). Secondary outcomes include patient acceptability, walking distance, CPET cardiorespiratory fitness measures and quality of life outcomes.Ethics and disseminationEthical approval was obtained via a local National Health Service research ethics committee (Bradford Leeds – 18/YH/0112) and recruitment began in August 2019 and will be completed in October 2020. Results will be published in peer-reviewed journals and presented at international conferences and are expected to inform a future pilot randomised controlled trial of HIIT versus usual-care SEPs.Trial registration numberNCT04042311; Pre-results.