Equation for the microwave backscatter cross section of aggregate snowflakes using the self-similar Rayleigh–Gans approximation

In this paper an equation is derived for the mean backscatter cross section of an ensemble of snowflakes at centimeter and millimeter wavelengths. It uses the Rayleigh–Gans approximation, which has previously been found to be applicable at these wavelengths due to the low density of snow aggregates. Although the internal structure of an individual snowflake is random and unpredictable, the authors find from simulations of the aggregation process that their structure is “self-similar” and can be described by a power law. This enables an analytic expression to be derived for the backscatter cross section of an ensemble of particles as a function of their maximum dimension in the direction of propagation of the radiation, the volume of ice they contain, a variable describing their mean shape, and two variables describing the shape of the power spectrum. The exponent of the power law is found to be −. In the case of 1-cm snowflakes observed by a 3.2-mm-wavelength radar, the backscatter is 40–100 times larger than that of a homogeneous ice–air spheroid with the same mass, size, and aspect ratio.

Objective Empirical Mode Decomposition metric

Empirical Mode Decomposition (EMD) is a data driven technique for extraction of oscillatory components from data. Although it has been introduced over 15 years ago, its mathematical foundations are still missing which also implies lack of objective metrics for decomposed set evaluation. Most common technique for assessing results of EMD is their visual inspection, which is very subjective. This article provides objective measures for assessing EMD results based on the original definition of oscillatory components.

Commodity risks and the cross-section of equity returns

The article examines whether commodity risk is priced in the cross-section of global equity returns. We employ a long-only equally-weighted portfolio of commodity futures and a term structure portfolio that captures phases of backwardation and contango as mimicking portfolios for commodity risk. We find that equity-sorted portfolios with greater sensitivities to the excess returns of the backwardation and contango portfolio command higher average excess returns, suggesting that when measured appropriately, commodity risk is pervasive in stocks. Our conclusions are robust to the addition to the pricing model of financial, macroeconomic and business cycle-based risk factors.

An Alternative Section Method for Casting and Posterior Laser Welding of Metallic Frameworks for an Implant-Supported Prosthesis

Purpose: The aim of this study was to compare the accuracy of fit of three types of implant-supported frameworks cast in Ni-Cr alloy: specifically, a framework cast as one piece compared to frameworks cast separately in sections to the transverse or the diagonal axis, and later laser welded. Materials and Methods: Three sets of similar implant-supported frameworks were constructed. The first group of six 3-unit implant-supported frameworks were cast as one piece, the second group of six were sectioned in the transverse axis of the pontic region prior to casting, and the last group of six were sectioned in the diagonal axis of the pontic region prior to casting. The sectioned frameworks were positioned in the matrix (10 N(.)cm torque) and laser welded. To evaluate passive fit, readings were made with an optical microscope with both screws tightened and with only one-screw tightened. Data were submitted to ANOVA and Tukey-Kramer`s test (p < 0.05). Results: When both screws were tightened, no differences were found between the three groups (p > 0.05). In the single-screw-tightened test, with readings made opposite to the tightened side, the group cast as one piece (57.02 +/- 33.48 mu m) was significantly different (p < 0.05) from the group sectioned diagonally (18.92 +/- 4.75 mu m) but no different (p > 0.05) from the group transversally sectioned (31.42 +/- 20.68 mu m). On the tightened side, no significant differences were found between the groups (p > 0.05). Conclusions: Results of this study showed that casting diagonally sectioned frameworks lowers misfit levels of prosthetic implant-supported frameworks and also improves the levels of passivity to the same frameworks when compared to structures cast as one piece.

Modified section method for laser-welding of ill-fitting cp Ti and Ni-Cr alloy one-piece cast implant-supported frameworks

P>This study aimed to verify the effect of modified section method and laser-welding on the accuracy of fit of ill-fitting commercially pure titanium (cp Ti) and Ni-Cr alloy one-piece cast frameworks. Two sets of similar implant-supported frameworks were constructed. Both groups of six 3-unit implant-supported fixed partial dentures were cast as one-piece [I: Ni-Cr (control) and II: cp Ti] and evaluated for passive fitting in an optical microscope with both screws tightened and with only one screw tightened. All frameworks were then sectioned in the diagonal axis at the pontic region (III: Ni-Cr and IV: cp Ti). Sectioned frameworks were positioned in the matrix (10-Ncm torque) and laser-welded. Passive fitting was evaluated for the second time. Data were submitted to anova and Tukey-Kramer honestly significant difference tests (P < 0 center dot 05). With both screws tightened, one-piece cp Ti group II showed significantly higher misfit values (27 center dot 57 +/- 5 center dot 06 mu m) than other groups (I: 11 center dot 19 +/- 2 center dot 54 mu m, III: 12 center dot 88 +/- 2 center dot 93 mu m, IV: 13 center dot 77 +/- 1 center dot 51 mu m) (P < 0 center dot 05). In the single-screw-tightened test, with readings on the opposite side to the tightened side, Ni-Cr cast as one-piece (I: 58 center dot 66 +/- 14 center dot 30 mu m) was significantly different from cp Ti group after diagonal section (IV: 27 center dot 51 +/- 8 center dot 28 mu m) (P < 0 center dot 05). On the tightened side, no significant differences were found between groups (P > 0 center dot 05). Results showed that diagonally sectioning ill-fitting cp Ti frameworks lowers misfit levels of prosthetic implant-supported frameworks and also improves passivity levels of the same frameworks when compared to one-piece cast structures.

Taxonomic survey of Paepalanthus section Diphyomene (Eriocaulaceae)

Paepalanthus is the largest genus in Eriocaulaceae, comprising about 400 species distributed mainly throughout the Neotropics. Through phylogenetic studies it has been demonstrated that the genus is polyphyletic, although many of its infrageneric categories are monophyletic. In an attempt to clarify the nomenclature and classification of Paepalanthus, we present a taxonomic survey of Paepalanthus section Diphyomene. This group consists of 10 species restricted to South America and is defined by inflorescences being arranged in the form of a tribotryum with terminal dibotryum, a terminal basic unit and pherophylls subtending the lateral dibotrya. Further important distinguishing characteristics are dimerous flowers, pistillate flowers with dolabriform sepals, bifid stigmatic branches and absent staminodes, and staminate flowers with an elongated anthophore. We hereby propose 19 new synonyms, six lectotypifications, one new status, one neotypification and one epitypification.

Five New and Narrowly Distributed Species of Paepalanthus Section Diphyomene (Eriocaulaceae) from Central Brazil

Five new species of Paepalanthus section Diphyomene are described and illustrated: P. brevis, P. flexuosus, P. longiciliatus, P. macer, and P. stellatus. Paepalanthus brevis, similar to P. decussus, is easily distinguished by its short reproductive axis, and pilose and mucronate leaves. Paepalanthus flexuosus, morphologically related to P. urbanianus, possesses a distinctive short and tortuous reproductive axis. Paepalanthus longiciliatus, morphologically similar to P. weddellianus, possesses long trichomes on the margins of the reproductive axis bracts, considered a diagnostic feature. Paepalanthus macer shares similarities with P. amoenus, differing by its sulfurous capitula and adpressed reproductive axis bracts. Paepalanthus stellatus also has affinity with P. decussus, but possesses unique, membranaceous, reproductive-axis bracts and a punctual inner-capitulum arrangement of pistillate flowers. Four of the described species are narrowly distributed in the state of Goias, whereas P. brevis is endemic to Distrito Federal. All are considered critically endangered. Detailed comparisons of these species are presented in tables. Comments on phenology, distribution, habitat and etymology, along with an identification key, are provided.

Baccharis scopulorum, a new species of section Caulopterae (Asteraceae: Astereae) from rocky cliffs of southern Brazil

A new species of Baccharis sect. Caulopterae endemic to rocky cliffs in southern Brazil, is here described as Baccharis scopulorum. This new species is characterized by the general presence of basal and persistent leaves, mostly solitary capitula born at the tips of the branches, and many flowered capitula, the pistillate capitula with an urceolate to campanulate involucres. The new species is morphologically most similar to B. altimontana and B. opuntioides, both inhabiting mountain summits in eastern Brazil. A description of B. scopulorum, together with illustrations, a distribution map, habitat description, conservation assessment and diagnostic comparison with B. altimontana and B. opuntioides is presented.