136 research outputs found

    A new species and new records of Aphodius Illiger (Coleoptera: Scarabaeidae: Aphodiinae) from mammal burrows in Nebraska

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    Direct sampling of rodent burrows in Nebraska resulted in the collection of 16 species of Aphodius Illiger previously unknown from the state, including specimens of four undescribed species. One of these species is described here as new: Aphodius viceversus new species recorded from Nebraska and Kansas. Other Aphodius species recorded from Nebraska for the first time include A. acuminatus Cartwright, A. anomaliceps Brown, A. carri Brown, A. criddlei Brown, A. kirni Cartwright, A. kiowensis Gordon and Salsbury, A. magnificens Robinson, A. neodistinctus Brown, A. peculiosus Schmidt, A. punctissimus Brown, A. thomomysi Brown, and A. leptotarsis Brown. Collecting information is summarized for each species

    A new genus for the Neotropical species of Aesalus Fabricius, with descriptions of eight new species (Coleoptera: Lucanidae: Aesalinae)

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    The Neotropical members of the genus Aesalus Fabricius (Coleoptera: Lucanidae: Aesalinae) are transferred to a new genus, Trogellus, due to their morphological dissimilarity and molecular divergence from the Old World species of Aesalus, and the new genus is revised. A neotype is designated for A. trogoides Albers and a lectotype for A. neotropicalis Bates. Aesalus smithi Bates is placed into synonymy with Aesalus trogoides, new synonymy. Two new combinations result from the transfer of species formerly in Aesalus: Trogellus trogoides from Mexico and Trogellus neotropicalis from Guatemala. In addition to the two known species, eight new species are described: T. catrachitus, T. chapinitus, T. hawksi, T. herrmanni, T. maesi, T. narizotus, T. ticiticus, and T. trifinius. This brings the total number of species of Central American aesalines to ten. A phylogeny of Aesalini based on two gene regions of ribosomal DNA is presented. Due to clear morphological differences and large molecular divergence between species groups, two additional new subgenera of Trogellus are proposed: Mayaesalus and Trogoides

    A new species of Parochodaeus Nikolajev from the southwestern United States (Coleoptera: Scarabaeoidea: Ochodaeidae)

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    A new species of Parochodaeus Nikolajev (Scarabaeoidea: Ochodaeidae) with extremely small adults is described from west Texas, P. pixius Paulsen. The species is compared with the sympatric P. biarmatus (LeConte), to which it is most similar in size

    Nomenclatural changes in the Nearctic Ochodaeinae and description of two new genera (Coleoptera: Scarabaeoidea: Ochodaeidae)

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    Generic placement of Nearctic species of Ochodaeinae has lagged behind changes in generic concepts in the group. In order to place Nearctic species into the appropriate genus-level taxa, several nomenclatural changes are made. The new generic name Xenochodaeus is proposed for species with an elongate, subparallel sulcus on the propygidium and a longitudinally impressed mentum. The genus contains 6 species. Xenochodaeus americanus (Westwood), new combination, is valid and is removed from synonymy with X. musculus (Say), new combination. A neotype is designated for Odontaeus musculus. Ochodaeus opacus LeConte is synonymized under X. americanus. Other new combinations include Xenochodaeus luscinus (Howden), X. planifrons (Schaeffer), X. simplex (LeConte), and X. ulkei (Horn). The new generic name Cucochodaeus is proposed for species having the propygidial sulcus absent, stridulatory peg absent, and possessing 9 antennomeres. The genus contains 1 species, C. sparsus (LeConte), new combination. Ochodaeus mandibularis Linell is placed into synonymy with C. sparsus. Ochodaeus gnatho Fall is transferred to the genus Codocera Eschscholtz, resulting in C. gnatho (Fall), new combination. Two new combinations result from Nearctic species transferred to Neochodaeus Nikolajev: N. repandus (Fall) and N. striatus (LeConte). Three Nearctic species are transferred to Parochodaeus Nikolajev, resulting in new combinations: Parochodaeus californicus (Horn), P. duplex (LeConte), and P. peninsularis (Horn). A lectotype is designated for Ochodaeus kansanus Fall, and that same specimen is designated as the neotype of Ochodaeus duplex (LeConte), objectively synonymizing O. kansanus with O. duplex. A checklist of Nearctic species and key to Nearctic genera are provided

    A second species of Lucanobium Howden and Lawrence from South America (Coleoptera: Lucanidae: Aesalinae)

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    The monotypic aesaline genus Lucanobium Howden and Lawrence (Coleoptera: Lucanidae) was previously known only from Venezuela. A second species is here described as new from French Guiana, extending the range of the genus approximately 1800 km to the southeast. The generic description of Lucanobium is updated with respect to the discovery of a second species

    Platyceroidini, a new tribe of North American stag beetles(Coleoptera: Lucanidae: Lucaninae)

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    The tribe Platyceroidini is created to accommodate two genera of North American stag beetles, Platyceroides Benesh and Platyceropsis Benesh (Lucanidae: Lucaninae). These genera are removed from the tribe Platycerini Mulsant

    A numerical framework for interstitial fluid pressure imaging in poroelastic MRE

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    A numerical framework for interstitial fluid pressure imaging (IFPI) in biphasic materials is investigated based on three-dimensional nonlinear finite element poroelastic inversion. The objective is to reconstruct the time-harmonic pore-pressure field from tissue excitation in addition to the elastic parameters commonly associated with magnetic resonance elastography (MRE). The unknown pressure boundary conditions (PBCs) are estimated using the available full-volume displacement data from MRE. A subzone-based nonlinear inversion (NLI) technique is then used to update mechanical and hydrodynamical properties, given the appropriate subzone PBCs, by solving a pressure forward problem (PFP). The algorithm was evaluated on a single-inclusion phantom in which the elastic property and hydraulic conductivity images were recovered. Pressure field and material property estimates had spatial distributions reflecting their true counterparts in the phantom geometry with RMS errors around 20% for cases with 5% noise, but degraded significantly in both spatial distribution and property values for noise levels > 10%. When both shear moduli and hydraulic conductivity were estimated along with the pressure field, property value error rates were as high as 58%, 85% and 32% for the three quantities, respectively, and their spatial distributions were more distorted. Opportunities for improving the algorithm are discussed

    Standard‐space atlas of the viscoelastic properties of the human brain

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    Standard anatomical atlases are common in neuroimaging because they facilitate data analyses and comparisons across subjects and studies. The purpose of this study was to develop a standardized human brain atlas based on the physical mechanical properties (i.e., tissue viscoelasticity) of brain tissue using magnetic resonance elastography (MRE). MRE is a phase contrast-based MRI method that quantifies tissue viscoelasticity noninvasively and in vivo thus providing a macroscopic representation of the microstructural constituents of soft biological tissue. The development of standardized brain MRE atlases are therefore beneficial for comparing neural tissue integrity across populations. Data from a large number of healthy, young adults from multiple studies collected using common MRE acquisition and analysis protocols were assembled (N = 134; 78F/ 56 M; 18–35 years). Nonlinear image registration methods were applied to normalize viscoelastic property maps (shear stiffness, μ, and damping ratio, ξ) to the MNI152 standard structural template within the spatial coordinates of the ICBM-152. We find that average MRE brain templates contain emerging and symmetrized anatomical detail. Leveraging the substantial amount of data assembled, we illustrate that subcortical gray matter structures, white matter tracts, and regions of the cerebral cortex exhibit differing mechanical characteristics. Moreover, we report sex differences in viscoelasticity for specific neuroanatomical structures, which has implications for understanding patterns of individual differences in health and disease. These atlases provide reference values for clinical investigations as well as novel biophysical signatures of neuroanatomy. The templates are made openly available (github.com/mechneurolab/mre134) to foster collaboration across research institutions and to support robust cross-center comparisons

    A Method for Serial Tissue Processing and Parallel Analysis of Aberrant Crypt Morphology, Mucin Depletion, and Beta-Catenin Staining in an Experimental Model of Colon Carcinogenesis

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    The use of architectural and morphological characteristics of cells for establishing prognostic indicators by which individual pathologies are assigned grade and stage is a well-accepted practice. Advances in automated micro- and macroscopic image acquisition and digital image analysis have created new opportunities in the field of prognostic assessment; but, one area in experimental pathology, animal models for colon cancer, has not taken advantage of these opportunities. This situation is primarily due to the methods available to evaluate the colon of the rodent for the presence of premalignant and malignant pathologies. We report a new method for the excision and processing of the entire colon of the rat and illustrate how this procedure permitted the quantitative assessment of aberrant crypt foci (ACF), a premalignant colon pathology, for characteristics consistent with progression to malignancy. ACF were detected by methylene blue staining and subjected to quantitative morphometric analysis. Colons were then restained with high iron diamine–alcian blue for assessment of mucin depletion using an image overlay to associate morphometric data with mucin depletion. The subsequent evaluation of ACF for beta-catenin staining is also demonstrated. The methods described are particularly relevant to the screening of compounds for cancer chemopreventive activity
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