How much does transmit correlation affect the sum-rate scaling of MIMO Gaussian broadcast channels?

This paper considers the effect of spatial correlation between transmit antennas on the sum-rate capacity of the MIMO Gaussian broadcast channel (i.e., downlink of a cellular system). Specifically, for a system with a large number of users n, we analyze the scaling laws of the sum-rate for the dirty paper coding and for different types of beamforming transmission schemes. When the channel is i.i.d., it has been shown that for large n, the sum rate is equal to M log log n + M log P/M + o(1) where M is the number of transmit antennas, P is the average signal to noise ratio, and o(1) refers to terms that go to zero as n → ∞. When the channel exhibits some spatial correlation with a covariance matrix R (non-singular with tr(R) = M), we prove that the sum rate of dirty paper coding is M log log n + M log P/M + log det(R) + o(1). We further show that the sum-rate of various beamforming schemes achieves M log log n + M log P/M + M log c + o(1) where c ≤ 1 depends on the type of beamforming. We can in fact compute c for random beamforming proposed in and more generally, for random beamforming with preceding in which beams are pre-multiplied by a fixed matrix. Simulation results are presented at the end of the paper

Synchrotron radiation study of the relation between structure and strain in polyurethane elastomers

This paper describes a system for the study of the relation between structure and applied strain in thermoplastic polyurethane elastomers using the Australian National Beamline Facility at the Photon Factory, KEK, Tsukuba, Japan. The system uses the sagittal focusing monochromator at beamline 20B to provide a high-intensity focused beam which then falls on the specimen mounted in a miniature tensometer mounted in the unique vacuum diffractometer (BIGDIFF). Imaging plates were used to record simultaneously SAXS and WAXS patterns from the specimen at a particular strain. The change in SAXS and WAXS patterns with loading and unloading was recorded using a ten-plate imaging-plate changer

At the Interface of Isomorphous Behavior in a 3 × 3 Isomer Grid of Monochlorobenzamides: Analyses of the Interaction Landscapes via Contact Enrichment Studies

International audienceThe physicochemical properties of a 33 isomer grid of mono-chlorobenzamides (Clxx) are reported with comprehensive studies of their crystal structures and interaction environments (Clx = para-/meta-/ortho-chlorobenzoyl and x = para-/meta-/ortho-aminopyridine substitutions). The nine compound Clxx series was synthesised from the three p-/m-/o-chlorobenzoyl chlorides and three p-/m-/o-aminopyridine isomers using standard synthetic procedures. Clxx exhibits some similarities to the related Fxx and Brxx congeners e.g. the isomorphous behaviour of Clpp (para-Chloro-N'-(para-pyridyl)benzamide) with several close relatives, and there are five isomorphous pairs of Clxx and Brxx crystal structures. Notably Clmp and Clpm both crystallise with Z'=4 in space group P but show important differences. The overall lack of isomers crystallising with solvate molecules is noteworthy, except for Clmm(H 2 O). In all Clxx crystal structures, strong N-H…N hydrogen bonds form, however, Clpo also crystallises as the unexpected Clpo_O polymorph with N-H…O=C intermolecular hydrogen bonding. The Clxo triad (with ortho-pyridines) exhibits the expected cyclic N-H…N dimer formation with R 2 2 (8) hydrogen bonded rings. The H C atom type, forming weak C-H…Cl hydrogen bonds, is the only favoured interaction partner of chlorine in Clxx. Conformational analyses (gas phase) together with crystal contact enrichment studies place Clxx in context and at the interface of hydrogen and halogen bonding interactions, though strong hydrogen bonding dominates. In Clxx the interaction energies with nearest neighbours are shown to contribute to most of the lattice electrostatic energies. The melting temperatures T m show correlation with both molecular symmetry (Carnelley's rule) and total electrostatic energy of the weak interactions; in addition, these T m values can be well predicted from a linear fit combining both descriptors. In Clxx, N-H…N hydrogen bonds dominate, largely in the absence of solvates, and with five Clxx forming isomorphous pairs with Brxx analogues; Clpp being isomorphous with several close benzamide relatives. Analysis of T m reveals correlations involving both symmetry and electrostatic energies

Estimation of the Serviceability of Forest Access Roads

The purpose of this study was to ascribe attributes to forest access roads, to allow for estimation of their serviceability on the basis of their current condition. The approach estimates the quantity of timber that may be hauled through without critically damaging the flexible pavements. Seventy-two roads were classified on the basis of their surface conditions, subgrade material, and surface deflection as the strength parameter, for 40 and 60 t Gross Vehicle Weight. Using non-parametric statistical techniques, it was found that the surface quality of pavements was largely dependent on drainage conditions (coefficient of determination r2 = 0.84), and that a strong relationship (r2 = 0.90) also existed between drainage and the number of potholes. Pavements with peat subgrades were found to exhibit significantly higher critical deflections (5.6 mm) than pavements with mineral subgrades (1 mm), coupled with their inherent variability, it is arguable that visual classification may not be suitable for such pavements. On the basis of these results, the serviceability of individual roads, in Equivalent Standard Axle Loads (ESAL) was estimated. Potential pavement damage by a standard 6 axle timber haulage truck, of 40 t Gross Vehicle Weight, with a payload of 27 t, was evaluated to be triple that due to a standard axle (8.16 t). Increasing the payload by about 10%, increased the ESAL required to transport a unit volume of timber, hence potential pavement damage, by 20%. Consequently, a significant reduction in the serviceability of forest access roads may be incurred by small overload margins that are usually ignored

Performance of a Differential GPS in Dynamic Mode Under Sitka Spruce Canopies

Quantified, performance indicators for dynamic mode Differential GPS (DGPS) were collected at 31 sites established under 3 canopy classes (none, pre-first thinning and mature) of Sitka spruce stands in Ireland with varying altitude (100-500 m) and aspect. Canopy cover was quantified using total obstruction, size of largest opening and fragmentation of sky view. At sites with no canopy above 2 m, a mean precision of 1.5 m was recorded. Where canopy was present, precision ranged between 2.6 m and 2.8 m. The results indicated that in dynamic mode, differences in DGPS performance between canopy cover types were limited to a presence/absence effect. oss of 3-dimensional operation (i.e. only 3 satellites in view) occurred more frequently than loss of differential correction signal and thus had a greater impact on recorded precision over the duration of the experiment. It was concluded from the data collected that the most versatile approach when using dynamic DGPS is to collect more (potentially poorer quality) data, rather than to apply a filter at the signal acquisition stage. The observations made, and the conclusions drawn in this paper are relevant to the forest industry in the selection and operation of DGPS equipment for dynamic tasks where ~ 2 m precision is required

Selectivity of organic products to Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae).

The selectivity of various entomopathogens and one insecticide (chlorpyrifos = positive control) to Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) was evaluated in the laboratory, using the protocol established by the Working Group on “Pesticides and Beneficial Organisms” of the IOBC. The evaluated parameters were parasitism (%), adult emergence (%), and product repellency to the parasitoid when sprayed on host eggs prior to parasitism (free-choice and no-choice tests). Most of the studied entomopathogens (Bacillus thuringiensis var. kurstaki, Bacillus thuringiensis var. aizawai, Beauveria bassiana, Metarhizium anisopliae, and Trichoderma harzianum) had no effects on biological parameters and were classified as harmless to T. pretiosum. Emergence of parasitoids (progeny viability) was reduced, but remained above 90%, when host eggs were sprayed with Baculovirus anticarsia prior to parasitism in the freechoice test, and B. anticarsia was therefore considered harmless. Chlorpyrifos (positive control) caused high adult parasitoid mortality in all bioassays. While T. pretiosum and the tested entomopathogens may be used simultaneously in integrated pest management programs, the use of chlorpyrifos should be avoided

Balanço hídrico climático de Juazeiro - BA.

O objetivo desse trabalho foi realizar o balanço hídrico climático de Juazeiro-BA, no período de 1967 a1998, gerando uma idéia do que acontece com boa parte da região semi-árida, no que diz respeito a disponibilidadede água, observando-se ainda a tendência climática temporal da região

Seletividade de Metarhizium anisopliae à Telenomus podisi (Hymenoptera: Scelionidae).

Telenomus podisi e Metarhizium anisopliae são agentes de controle biológico que ocorrem ou podem ser utilizados conjuntamente. Entretanto, estudos de compatibilidade entre parasitoides e fungos entomopatogênicos são escassos. O objetivo deste trabalho foi avaliar a seletividade do fungo M. anisopliae a adultos do parasitoide de ovos T. podisi. Suspensões de M. anisopliae (1,0×109 conídios/ml) foram pulverizadas sobre placas de vidro em Torre de Potter e secas à temperatura ambiente, formando uma película. Como testemunha foi utilizada água destilada estéril + Tween 80 (0,01%). As placas de vidro pulverizadas foram utilizadas na construção de gaiolas de exposição (IOBC) e em seu interior foram liberados adultos de T. podisi com 24 h de idade. As gaiolas foram mantidas em condições controladas de temperatura, umidade e fotoperiodo (25±1º C, 80% UR, 14 h) e os parasitóides foram alimentados com mel. Cartelas contendo ovos de Euschistus heros foram oferecidas às fêmeas de T. podisi 24 h, 48 h, 72 h e 144 h após a pulverização e, sendo posteriormente, acondicionadas em sacos plásticos para avaliar a porcentagem de parasitismo e viabilidade dos parasitoides. Os resultados obtidos indicam que mesmo com as aplicações de M. anisopliae, o parasitismo e a viabilidade foram superiores a 70%, mostrando que o fungo é seletivo aos adultos de T. podisi, sendo classificado como inócuo (classe 1), de acordo com a IOBC, e portanto, ambos os agentes de controle biológico podem ser utilizados no Manejo Integrado de Pragas.SICONBIOL 2011