685 research outputs found
Turbo Detection of Space-time Trellis-Coded Constant Bit Rate Vector-Quantised Videophone System using Reversible Variable-Length Codes, Convolutional Codes and Turbo Codes
In this treatise we characterise the achievable performance of a proprietary video transmission system, which employs a Constant Bit Rate (CBR) video codec that is concatenated with one of three error correction codecs, namely a Reversible Variable-Length Code (RVLC), a Convolutional Code (CC) or a convolutional-based Turbo Code (TC). In our investigations, the CBR video codec was invoked in conjunction with Space-Time Trellis Coding (STTC) designed for transmission over a dispersive Rayleigh fading channel. At the receiver, the channel equaliser, the STTC decoder and the RVLC, CC or TC decoder, as appropriate, employ the Max-Log Maximum A-Posteriori (MAP) algorithm and their operations are performed in an iterative 'turbo-detection' fashion. The systems were designed for maintaining similar error-free video reconstruction qualities, which were found to be subjectively pleasing at a Peak Signal to Noise Ratio (PSNR) of 30.6~dB, at a similar decoding complexity per decoding iteration. These design criteria were achieved by employing differing transmission rates, with the CC- and TC-based systems having a 22% higher bandwidth requirement. The results demonstrated that the TC-, RVLC- and CC-based systems achieve acceptable subjective reconstructed video quality associated with an average PSNR in excess of 30~dB for values above 4.6~dB, 6.4~dB and 7.7~dB, respectively. The design choice between the TC- and RVLC-based systems constitutes a trade-off between the increased error resilience of the TC-based scheme and the reduced bandwidth requirement of the RVLC-based scheme
Surveying structural complexity in quantum many-body systems
Quantum many-body systems exhibit a rich and diverse range of exotic
behaviours, owing to their underlying non-classical structure. These systems
present a deep structure beyond those that can be captured by measures of
correlation and entanglement alone. Using tools from complexity science, we
characterise such structure. We investigate the structural complexities that
can be found within the patterns that manifest from the observational data of
these systems. In particular, using two prototypical quantum many-body systems
as test cases - the one-dimensional quantum Ising and Bose-Hubbard models - we
explore how different information-theoretic measures of complexity are able to
identify different features of such patterns. This work furthers the
understanding of fully-quantum notions of structure and complexity in quantum
systems and dynamics.Comment: 9 pages, 5 figure
Forest specialist species in the urban landscape: Do different levels of urbanization affect the movements of Forest Red-tailed Black Cockatoos (Calyptorhynchus banksii naso)?
Anthropogenic landscape modification which leads to the displacement of species, is arguably one of the most profound impacts on animal movement globally. In urban landscapes, animal movement is generally impacted by varying levels of increased urbanization. However, this is species dependent and is mostly guided by the surrounding habitat. Fragmentation and habitat patch isolation must be considered at scales appropriate to the study species. Using telemetry, we test these assumptions investigating movement patterns of flocks of Forest Red-tailed Black Cockatoos (Calyptorhynchus banksii naso; RTBC) between three regions: urban, peri-urban, and forest using GPS and satellite PTT. This species occurs at varying levels of urbanization, however, how this might affect its movements is largely unknown. We did not find evidence that RTBC movement was impaired in the urban region compared with peri-urban or forest regions. It found, however, a significant within-region variation in movement extent among flocks and across regions depending on foraging resource availability and location. Differences in daily movement distance (Av. 4.96 - 16.41 km) and home range size (6.02 - 52.57 km2) between urban flocks appeared to be associated with the proximity of green spaces as roosts and foraging sites, with roadside vegetation providing important foraging resources and movement corridors. Key urban habitats were predominantly located in public nature reserves and private properties, with roadside vegetation connecting these sites for RTBC. The findings of this study highlight that conservation management for this and many other threatened species should regard the urban landscape as a critical habitat for urban adapted species. This would include management of its green spaces with connectivity and offsets from roads in mind. Furthermore, future research should focus on identifying additional key habitat sites (resource selection) and species distribution modeling, which will facilitate an active and adaptive approach towards this species' conservation management
6-Chloro-3-[5-(3-methoxy-8-methyl-4-quinolyl)-1-phenyl-4,5-dihydro-1H-pyrazol-3-yl]-2-methyl-4-phenylquinoline
In the title compound, C36H29ClN4O, the dihydropyrazole ring adopts an envelope conformation. The two quinoline ring systems (r.m.s. deviations = 0.029 and 0.018 Å) are oriented at a dihedral angle of 71.43 (4)°. One of the quinoline rings makes a dihedral angle of 65.40 (7)° with the phenyl substituent. In the crystal, molecules are linked into chains along the b axis by intermolecular C—H⋯N hydrogen bonds. In addition, C—H⋯π and π–π [centroid–centroid distance = 3.7325 (8) Å] interactions are observed
Soil water repellence increased early wheat growth and nutrient uptake
Purpose
Soil water repellence causes uneven soil wetting which can constrain dryland crop and pasture establishment and yield. The same processes are likely to affect nutrient availability from soil and fertiliser, but the effects of repellence on crop growth and nutrition per se have seldom been reported. Here, we investigated early wheat (Triticum aestivum cv. Mace) growth and nutrient uptake responses to repellence.
Methods
Wheat was furrow-sown in severely repellent sandy loam soil (with a wettable furrow base to allow for germination) or completely wettable soil, under uniform plant density and variable topsoil thickness (20 or 100 mm) and fertiliser band placement (below or away from the seed). Tiller number, shoot dry matter, shoot N concentration, total nutrient uptake, and root length density (RLD) were determined.
Results
Contrary to expectations, repellence significantly increased tiller number (by up to 2 tillers per plant), shoot dry matter (by 82%), shoot N concentration (by 0.3% N), and total nutrient uptake (by 87%) at 51 days after sowing, regardless of topsoil thickness and fertiliser placement. In the furrow, RLD of repellent treatments was also nearly double that in wettable treatments when fertiliser was banded below the seed. Results suggest that preferential soil wetting of the furrow in repellent treatments favoured plant nutrient uptake under regular but low water supply.
Conclusion
We conclude that for water-repellent soils with limited water supply, water harvesting techniques such as furrow sowing and banding wetting agents could boost water and nutrient uptake and early crop growth
Ferrocene-1-carbaldehyde 4-ethylthiosemicarbazone
The asymmetric unit of title compound, [Fe(C5H5)(C9H12N3S)], contains two crystallographically independent molecules, A and B. The two cyclopentadienyl (Cp) rings are parallel to each other in both molecules, forming dihedral angles of 2.3 (3) and 1.0 (3)°, respectively, and adopt an eclipsed conformation. The mean plane of the semicarbazone group is twisted slightly away from the attached Cp ring in both molecules, the dihedral angles between the mean plane and the Cp ring being 15.3 (2) and 10.8 (2)°. The ethyl group in molecule A is coplanar with the mean plane of the semicarbazone group [C—N—C—C torsion angle = −175.2 (4)°], whereas it is nearly perpendicular in molecule B [C—N—C—C torsion angle = 84.8 (6)°]. In the crystal structure, intermolecular N—H⋯S hydrogen bonds link the molecules into dimers. These dimers are further linked into chains via intermolecular C—H⋯S hydrogen bonds. The crystal studied was a non-merohedral twin with a refined ratio of the twin components of 0.265 (2):0.735 (2)
Bis(1-ferrocenylmethylidene-4-phenylthiosemicarbazidato-κ2 N 1,S)zinc(II) monohydrate
In the title compound, [Fe2Zn(C5H5)2(C13H11N3S)2]·H2O, the ZnII ion is in a distorted tetrahedral geometry being coordinated by two thiosemicarbazone ligands via N and S atoms. One of the Cp rings is disordered over two positions with occupancies of 0.55 and 0.45. The dihedral angle between the substituted Cp rings is 56.1 (5)° and the two phenyl rings are orientated at a dihedral angle of 41.7 (4)°. In the crystal structure, intermolecular O—H⋯S, N—H⋯O and C—H⋯N hydrogen bonds link the molecules into chains along the b axis. The structure is further consolidated by O—H⋯π interactions
4,5,6,7,8,9-Hexahydro-2H-cycloocta[c]pyrazol-1-ium-3-olate
The title compound, C9H14N2O, exists in the zwitterionic form in the crystal. The cyclooctane ring adopts a twisted boat-chair conformation. In the crystal, intermolecular N—H⋯O hydrogen bonds link the molecules into sheets lying parallel to bc. The structure is also stabilized by π–π interactions, with a centroid-to-centroid distance of 3.5684 (8) Å
Soil water repellence increased early wheat growth and nutrient uptake
Purpose:
Soil water repellence causes uneven soil wetting which can constrain dryland crop and pasture establishment and yield. The same processes are likely to affect nutrient availability from soil and fertiliser, but the effects of repellence on crop growth and nutrition per se have seldom been reported. Here, we investigated early wheat (Triticum aestivum cv. Mace) growth and nutrient uptake responses to repellence.
Methods:
Wheat was furrow-sown in severely repellent sandy loam soil (with a wettable furrow base to allow for germination) or completely wettable soil, under uniform plant density and variable topsoil thickness (20 or 100 mm) and fertiliser band placement (below or away from the seed). Tiller number, shoot dry matter, shoot N concentration, total nutrient uptake, and root length density (RLD) were determined.
Results:
Contrary to expectations, repellence significantly increased tiller number (by up to 2 tillers per plant), shoot dry matter (by 82%), shoot N concentration (by 0.3% N), and total nutrient uptake (by 87%) at 51 days after sowing, regardless of topsoil thickness and fertiliser placement. In the furrow, RLD of repellent treatments was also nearly double that in wettable treatments when fertiliser was banded below the seed. Results suggest that preferential soil wetting of the furrow in repellent treatments favoured plant nutrient uptake under regular but low water supply.
Conclusion:
We conclude that for water-repellent soils with limited water supply, water harvesting techniques such as furrow sowing and banding wetting agents could boost water and nutrient uptake and early crop growth
Two-gap and paramagnetic pair-breaking effects on upper critical field of SmFeAsO and SmFeAsOF single crystals
We investigated the temperature dependence of the upper critical field
[] of fluorine-free SmFeAsO and fluorine-doped
SmFeAsOF single crystals by measuring the resistive transition
in low static magnetic fields and in pulsed fields up to 60 T. Both crystals
show that 's along the c axis [] and in an -planar
direction [] exhibit a linear and a sublinear increase,
respectively, with decreasing temperature below the superconducting transition.
's in both directions deviate from the conventional one-gap
Werthamer-Helfand-Hohenberg theoretical prediction at low temperatures. A
two-gap nature and the paramagnetic pair-breaking effect are shown to be
responsible for the temperature-dependent behavior of and
, respectively.Comment: 21 pages, 8 figure
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