Identifying cryptic species and juveniles in the Ophiuroidea has always been a challenge. However, post-larval developmental studies have the potential to uncover the identity of these cryptic species and juveniles, as they offer valuable information that is not often found in adults. Although the importance of studying growth series is well-known in ophiuroids, it is difficult to obtain and identify the juvenile stages. For this reason, most studies are restricted to brooding species and information is lacking for many species, including those of the genus Ophiocoma. In this study, a growth series was developed to show the main differences during the development of two similar species of Ophiocoma: Ophiocoma echinata and Ophiocoma trindadensis. Using morphometry and scanning electron microscopy, we describe in detail the juveniles, intermediate stage, and adults of O. echinata and O. trindadensis. Differences in the shape of the ventral arm plate and dorsalmost arm spines, the number of tentacle scales, and the presence of granules ventrally were highlighted in the separation and identification of juveniles of both species.

Members of Sinistroporomonorchis Wee, Cutmore, Pérez-del-Olmo & Cribb, 2020 represent a small group of trematodes belonging to the Monorchiidae Odhner, 1911 with 5 species described from mugilid hosts. Specimens consistent with the generic concept of Sinistroporomonorchis were obtained from Floridichthys polyommus (Cyprinodontidae); most of them were juveniles from 4 localities within the Yucatán Peninsula. After a detailed morphological examination including scanning electron microscopy images and a principal component analysis, the specimens collected represented a new species, Sinistroporomonorchis bolini n. sp. The new species can be differentiated by the presence of an overall large pharynx including the proportion of pharynx width to oral sucker width, a uterus arranged in 2 main lateral fields, and by presenting robust caeca. In addition, sequences of the 28S of large subunit of nuclear ribosomal RNA and cox1 of the mitochondrial DNA were obtained. Phylogenetic trees inferred from each dataset, placed all the specimens in a monophyletic clade, confirming that the isolates belonged to the same species. The new species is the sixth described for the genus Sinistroporomonorchis, the fifth described from the Yucatán Peninsula and the first described from a non-mugilid host.

Typical Bayesian methods for models with latent variables (or random effects) involve directly sampling the latent variables along with the model parameters. In high-level software code for model definitions (using, e.g., BUGS, JAGS, Stan), the likelihood is therefore specified as conditional on the latent variables. This can lead researchers to perform model comparisons via conditional likelihoods, where the latent variables are considered model parameters. In other settings, however, typical model comparisons involve marginal likelihoods where the latent variables are integrated out. This distinction is often overlooked despite the fact that it can have a large impact on the comparisons of interest. In this paper, we clarify and illustrate these issues, focusing on the comparison of conditional and marginal Deviance Information Criteria (DICs) and Watanabe–Akaike Information Criteria (WAICs) in psychometric modeling. The conditional/marginal distinction corresponds to whether the model should be predictive for the clusters that are in the data or for new clusters (where “clusters” typically correspond to higher-level units like people or schools). Correspondingly, we show that marginal WAIC corresponds to leave-one-cluster out cross-validation, whereas conditional WAIC corresponds to leave-one-unit out. These results lead to recommendations on the general application of the criteria to models with latent variables.

Structural equation models are increasingly used as a modeling tool for multivariate time series data in the social and behavioral sciences. Standard error estimators of SEM models, originally developed for independent data, require modifications to accommodate the fact that time series data are inherently dependent. In this article, we extend a sandwich-type standard error estimator of independent data to multivariate time series data. One required element of this estimator is the asymptotic covariance matrix of concurrent and lagged correlations among manifest variables, whose closed-form expression has not been presented in the literature. The performance of the adapted sandwich-type standard error estimator is evaluated using a simulation study and further illustrated using an empirical example.

Applications of structural equation modeling (SEM) may encounter issues like inadmissible parameter estimates, nonconvergence, or unsatisfactory model fit. We propose a new factor rotation method that reparameterizes the factor correlation matrix in exploratory factor analysis (EFA) such that factors can be either exogenous or endogenous. The proposed method is an oblique rotation method for EFA, but it allows directional structural paths among factors. We thus referred it to as FSP (factor structural paths) rotation. In particular, we can use FSP rotation to “translate” an SEM model to incorporate theoretical expectations on both factor loadings and structural parameters. We illustrate FSP rotation with an empirical example and explore its statistical properties with simulated data. The results include that (1) EFA with FSP rotation tends to fit data better and encounters fewer Heywood cases than SEM does when there are cross-loadings and many small nonzero loadings, (2) FSP rotated parameter estimates are satisfactory for small models, and (3) FSP rotated parameter estimates are more satisfactory for large models when the structural parameter matrices are sparse.

OpenMx is free, full-featured, open source, structural equation modeling (SEM) software. OpenMx runs within the R statistical programming environment on Windows, Mac OS–X, and Linux computers. The rationale for developing OpenMx is discussed along with the philosophy behind the user interface. The OpenMx data structures are introduced—these novel structures define the user interface framework and provide new opportunities for model specification. Two short example scripts for the specification and fitting of a confirmatory factor model are next presented. We end with an abbreviated list of modeling applications available in OpenMx 1.0 and a discussion of directions for future development.

Imogolite occurs as tiny bumps less than 0.05 µm in diameter and about 0.3 µm long on amorphous thin layers on the surface of weathered plagioclase. The bumps grow outward from the surface to form projections, which then develop into a fibrous imogolite. The fibers branch out and grow into widespread networks or thin films which finally cover the entire surface of the plagioclase grain. The fibers are about 0.05 µm in diameter as seen by transmission electron microscopy.

A new chemical, Peldri II, is evaluated as a compound for drying soft clay materials. Peldri II, a fluorocarbon (1,1-difluorotetrachloroethane), is a solid at room temperature and is a liquid above 25°C. Clay gels are embedded in Peldri II by immersing them in the liquid and allowing it to solidify. Once solidified, Peldri II will sublime, with or without vacuum, to a dry specimen, probably without introducing surface tension. Wyoming montmorillonite saturated in 10−3 M NaCl and 1 M CaCl2 solutions has been examined to compare preservation of its initial structure after Peldri II, critical point, and freeze drying techniques. Transmission electron microscopy of ultrathin sections, scanning electron microscopy, and mercury intrusion porosimetry techniques were used. No differences were detected between Peldri II and critical point drying methods. Peldri II appears to be a significant improvement as an alternative drying agent for clay materials in studies of their structural properties. It is also very convenient for drying large numbers of samples.

Muscovite-kaolinite intergrowths found in Albian sandstones of the Basque Cantabrian basin (northern Spain) were studied by optical, scanning and electron microscopy and electron microprobe analysis. Kaolinitization begins at grain edges, forming the characteristic fanned-out textures, and propagates toward the interior along the cleavages of muscovite. Kaolinite and muscovite occur as thick packets, being free of interlayering. Phase boundaries between both minerals show bidimensional crystallographic continuity, and no intermediate phases have been identified. The data obtained suggest that muscovite only supplied a template suitable for the epitactic crystallization of kaolinite, while Al was available in sufficient amounts due to the dissolution of detrital K-feldspar. Very small packets of magnetite or maghemite showing a coherent orientation with the kaolinite crystals have been recognized, and could be responsible for the small Fe contents usually detected in electron microprobe analyses of kaolinite.

Textural relationships between authigenic kaolinite and deformation microstructures in the intergrowths, combined with previous information about burial conditions, show that alteration proceeded during a late stage of the diagenetic history, related to the uplift of the studied materials as a result of the Alpine orogeny.

A 3-cm-thick, two-layered clay unit that records mineralogic and textural evidence of a catastrophic event that occurred at a time now marked as the end of the Cretaceous Period was preserved in ancient peat-forming environments of the Western Interior Basin of North America. The two layers of this unit consist of altered distal ejecta and are easily distinguished by their distinctive texture and impact components from other clay beds, mainly tonsteins and detrital shales, occurring within the sequence of rocks enclosing the Cretaceous/Tertiary (K/T) boundary interval.

The lower claystone layer of the K/T boundary unit represents melted silicic target rock that has altered mainly to kaolin minerals. Impact components and signatures of this lower layer include a relict imbricate fabric of glass fragments, shards, bubbles, hollow spherules (altered microtektites), small amounts of shocked mineral grains, and a subdued iridium anomaly. These components and textures, combined with the layer's restricted areal distribution, indicate that this layer, called the “melt ejecta layer,” is the distal part of an ejecta blanket deposit. We interpret the melt ejecta layer to be an altered deposit of mostly impact-derived, shock-melted, silicic target material that traveled through the atmosphere within a detached ejecta curtain and on other ballistic trajectories.

The upper laminated layer of the K/T boundary unit consists mostly of altered vitric dust and abundant shocked minerals whose size and amounts decrease away from the putative crater site in the Caribbean area. High-nickel magnesioferrite crystals, high iridium content, geochemical signature, and worldwide distribution all suggest this upper layer originated from a cloud of vaporized bolide and entrained target-rock materials ejected above the atmosphere. The components of this layer, called the “fireball layer,” settled slowly by gravitational processes from an Earth-girdling vapor cloud and were deposited immediately on top of the already-emplaced melt ejecta layer.

The clay minerals that formed in the two layers are largely a function of composition and the highly unstable, shock-modified state of the fallout materials altered in acidic, organic-rich waters of ancient peat swamps. The fireball layer is mostly altered to smectitic clay from a mafic glass condensed from the vaporized chondritic bolide, along with some kaolinite formed from blebs of melted silicic target material entrained in the vapor plume cloud during ejection. In contrast, the melt ejecta layer is mainly kaolinitic, derived from silicic glass formed from melted target rocks. In this layer, the glass rapidly altered to mostly disordered, micrometer-sized “cabbage-like” or submicrometer-sized embryonic forms of spherical halloysite, probably from an allophane precursor. These crystallization characteristics of the melt ejecta layer are much different than those which formed coarse vermicular aggregates and platy kaolinite crystals in tonsteins from outside the K/T boundary interval throughout the Western Interior. The contrast in the incipient formation of dominantly kaolinitic clay minerals in the basal melt ejecta layer and of smectitic clay minerals in the overlying fireball layer reflect silicic versus mafic starting materials, respectively, and also supports the proposed two-phased meteorite impact ejection and dispersal model.

During subsequent burial and diagenesis of the K/T boundary unit, the metastable halloysite and smectite aggraded to kaolinite and mixed-layer illite/smectite, respectively. Both the ordering of kaolinite and illitization of smectite varies locally as a function of the degree of diagenetic grade or maturity, probably in response to local variations in temperature due to maximum burial depth (burial diagenesis).

The hot spring water discharging from a flank of an active volcano is precipitating unique monomineralic manganese deposits over volcanic terrain. The major and trace element chemistry, XRD mineralogy, DTA, and SEM observations indicate that the deposits consist of 10 Å phyllomanganate (buserite) accommodating inter-layer Ca and Mg with negligible amounts of detrital minerals. Other metallic elements can be accommodated by buserite, but concentrations are negligible ranging less than 10 ppm to 500 ppm. Abundance and pattern of REE (less than 100 ppm in total) are similar to those from hydrothermal manganese deposits. The buserite is enriched in Ca and Mg but depleted in Na in comparison with those in the spring water. The distribution coefficients for Ca, Mg and Na between the buserite and the host water were calculated assuming an ion-exchange equilibrium in the Yuno-Taki Fails, which proved applicable to other manganese deposits from surficial environments on land and oceans.

Polynuclear Al13 tridecamer species are the major hydrolyzed species of aluminum, but their occurrence in terrestrial environments has not been established. X-ray diffraction (XRD), 27Al nuclear magnetic resonance (NMR), and scanning electron microscope (SEM) analyses show that the presence of tartaric acid (concentration range of 10−5–10−3 M), one of the commonly occurring low-molecular-weight organic acids, inhibits the formation of the Al13 tridecamer species.

In the absence of tartaric acid, the basic aluminum sulfate crystals were of tetrahedral morphology and conformed to isometric symmetry with a = 17.748 Å and space group of P4232. Increasing amounts of tartaric acid [tartaric acid/Al molar ratio (R) ranging from 0.01 to 0.05] modified the crystal morphology from the tetrahedral particles of isometric symmetry (R = 0) to rod-shaped particles of monoclinic symmetry (R = 0.01) to irregularly shaped X-ray noncrystalline microparticles (R = 0.05). Failure to detect the presence of Al13 tridecamer, the dominant hydrolyzed species of aluminum, in terrestrial environments may be partially attributed to the presence of low-molecular-weight organic acids, which inhibit the formation of Al13 tridecamer species.

The composition and origin of vanadium-bearing clay minerals in the Jurassic (Morrison and Entrada Formations) sandstones of the Colorado Plateau are reassessed using microanalyses (microprobe and scanning electron microscope). The main V-clays are authigenic illite and chlorite of various petrologic habits: clay casts and matrix, pore lining, replacement of detrital grains. The chemical composition of the V-clays is similar in three different localities in the Morrison Formation separated by about 50 km, suggesting that the V-clays are the result of a large regional event. In both illite and chlorite, Al and V are inversely correlated, showing that V replaces Al in the octahedral position. The chlorite contains a complex mixture of divalent and trivalent cations that cannot fit within a sudoite structure. A classification of V-micas is proposed that employs V3+/sum of the octahedral cations vs. the sum of the interlayer charges. V-illite and roscoelite from the Colorado Plateau are characteristic of diagenetic/hydrothermal environments. For a given locality the composition of the V-clays does not vary with habit, showing that these minerals formed at thermodynamic equilibrium.

The OH-stretching region in curve-fitted micro-Raman, photoacoustic and transmission IR spectra of St. Claire dickite was investigated. Polarized Raman spectra recorded from th. (001) an. (010) faces of the dickite crystal displayed six prominent OH bands. The relative intensities depend strongly on both the orientation of the crystallographic axes and the direction of the electric vector of the laser beam. Four out-of-plane vibrations, AA, Az, CA and Cz, at ~3710, 3706, 3654 and 3643 cm-1 respectively, predominate when the electric vector is perpendicular to the dickite plates. Two in-plane vibrations, Dz and DA at 3627 and 3623 cm-1, intensify when the electric vector is parallel to the plane. The relationship between band intensity and crystal orientation was interpreted in terms of longitudinal optic (LO) and transverse optic (TO) crystal vibration modes. These LO and TO crystal modes were also observed in curve-fitted photoacoustic and transmission IR spectra of coarse, non-oriented crystals of the dickite.

Upper Cretaceous-Tertiary marine clayey-calcareous rocks of the Hekimhan basin contain fibrous clay minerals in significant amounts. Ophiolitic rocks in the provenance area have contributed the elements to form the clay minerals. XRD, SEM, major, trace and REE analyses were applied to samples taken from several stratigraphic sections. Diagenetic minerals such as smectite, dolomite, calcite, gypsum, celestite and quartz/chalcedony are associated with sepiolite-palygorskite group clays. Trace and rare earth elements (REE) are more abundant in palygorskite than sepiolite. REE abundances in the sepiolite-palygorskite are characterized by negative Eu and positive Nd anomalies when normalized with respect to chondrite and shale. Sepiolites with sharp XRD peaks are formed by diagenetic replacement of dolomite and diagenetic transformation of palygorskite, or by direct crystallization from solution. The average structural formula of the sepiolite is:

(Mg7.15Al0.13Fe0.31Cr0.06Ni0.04)(Si11.98Al0.02)O30(OH)4(OH2)4Ca0.03Na0.02K0.02.8H2O

Palygorskite appears to be authigenic by direct precipitation from solution. It exists in both monoclinic and orthorhombic forms with the mean structural formula given below

(Mg2.22Al1.00Ti0.04Fe0.77Cr0.01Ni0.02)(Si7.68Al0.32)O20(OH)2(OH2)4Ca0.07Na0.05K0.10.4H2O

Highly tectonized contact between serpentinite and younger pegmatite in the magnesite mine of Wiry contains various layer silicates. Vermiculite, chlorite, smectite, and interstratified mica-vermiculite were recognized by means of routine XRD examination. Two three component interstratifications of mica-vermiculite-chlorite and chlorite-swelling chlorite-smectite were identified by a combined procedure of deconvolution of the XRD patterns and simulation of XRD tracings. A mineral with large diffraction maxima, displaying “chlorite intergrade” characteristics, appeared to be a mixture of chlorite, mixed layer chlorite-smectite, and vermiculite. Polytypes of phyllosilicates were determined by the X-ray transmission method. Due to the heritage of parent mineral polytype structure by transitional products of alteration, two distinct sequences of layer silicates were observed: one formed from trioctahedral mica (vermiculite, mixed layer mica-vermiculite); and one evolved from chlorite (e.g., mixed layer chlorite-swelling chloritesmectite). A tentative scheme of the primary contact zone structure, not obscured by subsequent brittle tectonics either by transformation of layer silicates, is proposed.