The maximum number of minimal codewords in an [n,k]−[n,k]-code

Upper and lower bounds are derived for the quantity in the title, which is tabulated for modest values of $n$ and $k.$ An application to graphs with many cycles is given.Comment: 6 pp. Submitte

The analysis of various size, visually selected and density and magnetically separated fractions of Luna 16 and 20 samples

Samples of Luna 16 and 20 have been separated according to size, visual appearance, density, and magnetic susceptibility. Selected aliquots were examined in eight British laboratories. The studies included mineralogy and petrology, selenochronology, magnetic characteristics, Mossbauer spectroscopy, oxygen isotope ratio determinations, cosmic ray track and thermoluminescence investigations, and carbon chemistry measurements. Luna 16 and 20 are typically mare and highland soils, comparing well with their Apollo counterparts, Apollo 11 and 16, respectively. Both soils are very mature (high free iron, carbide, and methane and cosmogenic Ar), while Luna 16, but not Luna 20, is characterized by a high content of glassy materials. An aliquot of anorthosite fragments, handpicked from Luna 20, had a gas retention age of about 4.3 plus or minus 0.1 Gy

An analysis of the proposed Dutch yardstick mechanism

Health care provision is undergoing major reforms in Europe as a reaction to rapidly increasing expenditure and lowered political acceptance to commit public finance to cover the deficits. The Dutch government will decide in 2007 if the current budget system will be replaced by a more competitive mechanism, based on the yardstick regulation principle by Shleifer (1985). One of the proposed systems for the reform can be compared to a revenue-cap implementation of a multi-product cost-yardstick mechanism. The redistribution of the sector’s relevant cost is made in proportion to the individual hospitals share of total weighted output. No regulation is made of the multi-lateral contractual relations between users, insurers and hospitals. The scaling weights are updated periodically for new services and as a function of observed excess demand (waiting lists). The mechanism is shown to provide cost-reducing (effort-inducing) incentives for profit-maximizing rational agents in a single-period bargaining game. The game also shows that the regulation acts as a countervailing power for the insurers to reinforce bargaining power. The local distortion of the output profile induced by the regulation is a function of demand elasticity and cost function convexity. In case the revenue target is not binding, no welfare loss is incurred. The regime also provides incentives for cost-reducing investments in the short and the long run. These incentives manifest themselves in local reallocations of output to more efficient producers. The analysis shows that care should be taken in the updating of the weights as to provide incentives for service innovation, as well as to guarantee convergence of the price system. Although this requires econometric analyses, the alternative with a cost-based yardstick is considered superior to a revenue-based ditto for this application

Fe-substituted mullite powders for the in situ synthesis of carbon nanotubes by catalytic chemical vapor deposition

Powders of iron-substituted mullite were prepared by combustion and further calcination in air at different temperatures. A detailed study involving notably Mo¨ssbauer spectroscopy showed that the Fe3+ ions are distributed between the mullite phase and a corundum phase that progressively dissolves into mullite upon the increase in calcination temperature. Carbon nanotube-Fe-mullite nanocomposites were prepared for the first time by a direct method involving a reduction of these powders in H2-CH4 and without any mechanical mixing step. The carbon nanotubes formed by the catalytic decomposition of CH4 on the smallest metal particles are mostly double-walled and multiwalled, although some carbon nanofibers are also observed

Multicore implementation of a fixed-complexity tree-search detector for MIMO communications

[EN] Multicore systems allow the efficient implementation of signal processing algorithms for communication systems due to their high parallel processing capabilities. In this paper, we present a high-throughput multicore implementation of a fixed-complexity tree-search-based detector interesting for MIMO wireless communication systems. Experimental results confirm that this implementation allows to accelerate the data detection stage for different constellation sizes and number of subcarriers.This work was supported by the TEC2009-13741 project of the Spanish Ministry of Science, by the PROMETEO/2009/013 project and ACOMP/2012/076 of the Generalitat Valenciana, and the Vicerrectorado de Investigacion de la UPV through Programa de Apoyo a la Investigacion y desarrollo (PAID-05-11-2898).Ramiro Sánchez, C.; Roger Varea, S.; Gonzalez, A.; Almenar Terré, V.; Vidal Maciá, AM. (2013). Multicore implementation of a fixed-complexity tree-search detector for MIMO communications. The Journal of Supercomputing (Online). 65(3):1010-1019. https://doi.org/10.1007/s11227-012-0839-xS10101019653Paulraj AJ, Gore DA, Nabar RU, Bölcskei H (2004) An overview of MIMO communications—a key to gigabit wireless. Proc IEEE 92(2):198–218Jiang M, Hanzo L (2007) Multiuser MIMO-OFDM for next-generation wireless systems. Proc IEEE 95(7):1430–14693GPP TS 36.201, V10.0.0, Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer—general description, December 2010Lin Y, Lee H, Woh M, Harel Y, Mahlke S, Mudge T, Chakrabarti C, Flautner K (2007) SODA: a high-performance DSP architecture for software-defined radio. IEEE MICRO 27(1):114–123Yang C-H, Markovic D (2008) A multi-core sphere decoder VLSI architecture for MIMO communications. In: Global telecommunications conference, November, pp 1–6Wu D, Eilert J, Liu D (2011) Implementation of a high-speed MIMO soft-output symbol detector for software defined radio. J Signal Process Syst 63(1):27–37Tan K, Liu H, Zhang J, Zhang Y, Fang J, Voelker GM (2011) Sora: high-performance software radio using general-purpose multi-core processors. Communun ACM 54(1):99–107Roger S, Ramiro C, Gonzalez A, Almenar V, Vidal AM (2012) An efficient GPU implementation of fixed-complexity sphere decoders for MIMO wireless systems. Integr Comput-Aided Eng 19(4):341–350Chen Y-K et al (2009) Signal processing on platforms with multiple cores: Part 1-Overview and methodologies. IEEE Signal Proc Mag 6:24–25Karam LJ, AlKamal I, Gatherer A, Frantz GA, Anderson DV, Evans BL (2009) Trends in multicore DSP platforms. IEEE Signal Process Mag 26(6):38–49Barbero LG, Thompson JS (2008) Fixing the complexity of the sphere decoder for MIMO detection. IEEE Trans Wirel Commun 7(6):2131–2142Hassibi B, Vikalo H (2005) On sphere decoding algorithm. Part I, The expected complexity. IEEE Trans Signal Process 54(5):2806–2818Agrell E, Eriksson T, Vardy A, Zeger K (2002) Closest point search in lattices. IEEE Trans Inf Theory 48(8):2201–2214OpenMP v3.0, http://www.openmp.org/mp-documents/spec30.pdf , May 200

How predation and landscape fragmentation affect vole population dynamics

Background: Microtine species in Fennoscandia display a distinct north-south gradient from regular cycles to stable populations. The gradient has often been attributed to changes in the interactions between microtines and their predators. Although the spatial structure of the environment is known to influence predator-prey dynamics of a wide range of species, it has scarcely been considered in relation to the Fennoscandian gradient. Furthermore, the length of microtine breeding season also displays a north-south gradient. However, little consideration has been given to its role in shaping or generating population cycles. Because these factors covary along the gradient it is difficult to distinguish their effects experimentally in the field. The distinction is here attempted using realistic agent-based modelling. Methodology/Principal Findings: By using a spatially explicit computer simulation model based on behavioural and ecological data from the field vole (Microtus agrestis), we generated a number of repeated time series of vole densities whose mean population size and amplitude were measured. Subsequently, these time series were subjected to statistical autoregressive modelling, to investigate the effects on vole population dynamics of making predators more specialised, of altering the breeding season, and increasing the level of habitat fragmentation. We found that fragmentation as well as the presence of specialist predators are necessary for the occurrence of population cycles. Habitat fragmentation and predator assembly jointly determined cycle length and amplitude. Length of vole breeding season had little impact on the oscillations. Significance: There is good agreement between our results and the experimental work from Fennoscandia, but our results allow distinction of causation that is hard to unravel in field experiments. We hope our results will help understand the reasons for cycle gradients observed in other areas. Our results clearly demonstrate the importance of landscape fragmentation for population cycling and we recommend that the degree of fragmentation be more fully considered in future analyses of vole dynamics

Lunar meteorite Northwest Africa 11962: A regolith breccia containing various examples of titanium-rich lunar volcanism and the high alkali suite.

The meteorite Northwest Africa (NWA) 11962 has been recently classified as a lunar regolith breccia. For the present study, the clasts and the matrix of NWA 11962 have been characterized by optical and electron microscopy along with electron microprobe analyses. The meteorite has a glassy impact melt matrix, which accounts for 35% of the surface area in the thin sections examined, and which contains a very large variety of different lithic clasts, monomineralic clasts, and glass fragments. Lithic clasts include numerous fragments of quartz monzogabbro and lunar felsite, which are quite rare lithologies in the lunar alkali suite. However, the most abundant component in the breccia are gabbroic clasts. The mineral chemistry of the pyroxenes in these gabbroic clasts and the chemistry of various types of glasses in the breccia indicate an origin of the regolith from an area with low-Ti to high-Ti mare basalt volcanism. In addition to the peculiar petrographic characteristics of NWA 11962, the possible pairing relation with the NWA 4472/4485 group of lunar meteorites is discussed

Infrared method for determining circadian patterns of carbon dioxide release

Using an infrared technique based on the continuous monitoring of a characteristic infrared absorption band, temporal variations in the circadian patterns of carbon dioxide release were examined in two species of noctuid moths, the corn earworm Heliothis zea ( Boddie ) and the fall armyworm Spodoptera frugiperda ( J. E. Smith ). The detailed emission patterns were shown to be different in the two moth species (Figs. 3, 4). Emission patterns similar to those obtained in adults were also observed to be present in the pupal stage of development.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47098/1/359_2004_Article_BF00302280.pd

Characteristics of homogeneous multi-core fibers for SDM transmission

We describe optical data transmission systems using homogeneous, single-mode, multi-core fibers (MCFs). We first briefly discuss space-division multiplexing (SDM) fibers, observing that no individual SDM fiber offers overwhelming advantages over bundles of single-mode fiber (SMF) across all transmission regimes. We note that for early adoption of SDM fibers, uncoupled or weakly coupled fibers which are compatible with existing SDM infrastructure have a practical advantage. Yet, to be more attractive than parallel SMF, it is also necessary to demonstrate benefits beyond improved spatial spectral efficiency. It is hoped that the lower spread of propagation delays (skew) between spatial channels in some fibers can be exploited for improved performance and greater efficiency from hardware sharing and joint processing. However, whether these benefits can be practically harnessed and outweigh impairments or effort to mitigate cross talk between spatial channels is not yet clear. Hence, focusing on homogeneous MCFs, we first describe measurements and simulations on the impact of inter-core cross talk in such fibers before reporting experimental investigation into the spatial channel skew variation with a series of the experimental results including a comparison with SMF in varying environmental conditions. Finally, we present some system and transmission experiments using parallel recirculating loops that enable demonstration of both multi-dimensional modulation and joint digital processing techniques across three MCF cores. Both techniques lead to increased transmission reach but highlight the need for further experimental analysis to properly characterize the potential benefits of correlated propagation delays in such fibers