118,864 research outputs found
Theoretical 3D Fourier maps of electrostatic potential and electron density generated with TAAM structure factors for lysozyme
No full textThe dataset contains 3D Fourier maps of electrostatic potential and electron density for lysozyme generated with the transferable aspherical atom model (TAAM) using the UBDB/MATTS data bank, the associated structural model of lysozyme and structure factors files.For the technical details on the method to generate the Fourier maps of electrostatic potential and electron density and for the theoretical background on the method, see (Kulik et al., 2022).The Fourier maps were generated using the atomic coordinates and B-factors from the model of lysozyme structure from Gallus gallus (PDB ID 5k7o (de la Cruz et al., 2017)). The LSDB program (Volkov et al., 2004) was used to automatically assign the UBDB2018 atom type parameters (Kumar et al., 2019) to all atoms. DiSCaMB library, available at http://4xeden.uw.edu.pl/software/ (Chodkiewicz et al., 2018), was used to calculate the structure factors for X-ray diffraction for the TAAM with UBDB2018 parameters at given resolution and then to convert them to the structure factors for electron diffraction using the Mott-Bethe formula. The 3D Fourier maps of electrostatic potential (eTAAM) and electron density (xTAAM) were generated using the WinXD2016 package (Volkov et al., 2016) XDFOUR module at resolutions from 1 Å to 4 Å every 1 Å, and with voxel size 0.3 Å. The maps were generated in two versions: with or without taking into account the thermal smearing effects (denoted as with B or without B, respectively). The same set of B-factors was applied at every resolution in the Fourier maps that include the thermal smearing effects. The 3D Fourier maps deposited here were trimmed with a 3 Å margin around the protein and were not scaled. The associated structural model of lysozyme contains hydrogen atoms and B-factors as used for all the calculations.The structure factors files feature seven columns. The first three columns correspond to the reflection indices up to 1 Å resolution. Next, there are two sets of Fourier coefficients. The first two coefficients correspond to the real and imaginary parts of the TAAM structure factors, respectively. Additionally, we provide the second set of coefficients that correspond to the real and imaginary parts of the IAM structure factors. The structure factors files make it possible to generate the 3D Fourier maps of electrostatic potential and electron density calculated with TAAM or IAM, with or without taking into account the thermal smearing effects (denoted as with B or without B, respectively) at any given resolution worse than or equal to 1 Å.References:Kulik, M., Chodkiewicz, M. L. & Dominiak, P. M. (2022). Acta Crystallographica Section D, 78(8), 1010–1020.de la Cruz, M. J., Hattne, J., Shi, D., Seidler, P., Rodriguez, J., Reyes, F. E., Sawaya, M. R., Cascio, D., Weiss, S. C., Kim, S. K., Hinck, C. S., Hinck, A. P., Calero, G., Eisenberg, D. & Gonen, T. (2017). Nat Methods, 14(4), 399–402.Volkov, A., Li, X., Koritsanszky, T. & Coppens, P. (2004). J. Phys. Chem. A, 108, 4283–4300.Kumar, P., Gruza, B., Bojarowski, S. A. & Dominiak, P. M. (2019). Acta Crystallogr A Found Adv, 75(Pt 2), 398–408.Chodkiewicz, M. L., Migacz, S., Rudnicki, W., Makal, A., Kalinowski, J. A., Moriarty, N. W., Grosse-Kunstleve, R. W., Afonine, P. V., Adams, P. D. & Dominiak, P. M. (2018). J Appl Crystallogr, 51(Pt 1), 193–199.Volkov, A., Macchi, P., Farrugia, L. J., Gatti, C., Mallinson, P., Richter, T. & Koritsanszky, T., (2016). XD2016 - a computer program package for multipole refinement, topological analysis of charge densities and evaluation of intermolecular energies from experimental and theoretical structure factors.</p
Theoretical 3D Fourier maps of electrostatic potential generated with TAAM structure factors for lysozyme with bulk solvent
No full textThe dataset contains 3D Fourier maps of electrostatic potential for lysozyme with bulk solvent generated with the transferable aspherical atom model (TAAM) using the UBDB/MATTS data bank, the associated structural model of lysozyme with bulk solvent and structure factors file.For the technical details on the method to generate the Fourier maps of electrostatic potential and for the theoretical background on the method, see Kulik et al., 2022.The Fourier maps were generated using the atomic coordinates and B-factors from the model of lysozyme structure from Gallus gallus (PDB ID 5k7o (de la Cruz et al., 2017)) with additional 762 water molecules to fill the whole unit cell volume. The LSDB program (Volkov et al., 2004) was used to automatically assign the UBDB2018 atom type parameters (Kumar et al., 2019) to all atoms. DiSCaMB library, available at http://4xeden.uw.edu.pl/software/ (Chodkiewicz et al., 2018), was used to calculate the structure factors for X-ray diffraction for the TAAM with UBDB2018 parameters at given resolution and then to convert them to the structure factors for electron diffraction using the Mott-Bethe formula. The 3D Fourier maps of electrostatic potential (eTAAM) were generated using the WinXD2016 package (Volkov et al., 2016) XDFOUR module at resolutions 1 Å and 4 Å, and with voxel size 0.3 Å. The maps were generated with the thermal smearing effects, using the same set of B-factors at both resolutions. The 3D Fourier maps deposited here were trimmed with a 3 Å margin around the protein and were not scaled. The structure factors file features seven columns. The first three columns correspond to the reflection indices up to 1 Å resolution. Next, there are two sets of Fourier coefficients. The first two coefficients correspond to the real and imaginary parts of the TAAM structure factors, respectively. Additionally, we provide the second set of coefficients that correspond to the real and imaginary parts of the IAM structure factors. The structure factors files make it possible to generate the 3D Fourier maps of electrostatic potential and electron density calculated with TAAM or IAM, with or without taking into account the thermal smearing effects (denoted as with B or without B, respectively) at any given resolution worse than or equal to 1 Å.References:Kulik, M., Chodkiewicz, M. L. & Dominiak, P. M. (2022). Acta Crystallographica Section D, 78(8), 1010–1020.de la Cruz, M. J., Hattne, J., Shi, D., Seidler, P., Rodriguez, J., Reyes, F. E., Sawaya, M. R., Cascio, D., Weiss, S. C., Kim, S. K., Hinck, C. S., Hinck, A. P., Calero, G., Eisenberg, D. & Gonen, T. (2017). Nat Methods, 14(4), 399–402.Volkov, A., Li, X., Koritsanszky, T. & Coppens, P. (2004). J. Phys. Chem. A, 108, 4283–4300.Kumar, P., Gruza, B., Bojarowski, S. A. & Dominiak, P. M. (2019). Acta Crystallogr A Found Adv, 75(Pt 2), 398–408.Chodkiewicz, M. L., Migacz, S., Rudnicki, W., Makal, A., Kalinowski, J. A., Moriarty, N. W., Grosse-Kunstleve, R. W., Afonine, P. V., Adams, P. D. & Dominiak, P. M. (2018). J Appl Crystallogr, 51(Pt 1), 193–199.Volkov, A., Macchi, P., Farrugia, L. J., Gatti, C., Mallinson, P., Richter, T. & Koritsanszky, T., (2016). XD2016 - a computer program package for multipole refinement, topological analysis of charge densities and evaluation of intermolecular energies from experimental and theoretical structure factors.</p
Theoretical 3D Fourier maps of electrostatic potential and electron density generated with TAAM structure factors for proteinase K
No full textThe dataset contains 3D Fourier maps of electrostatic potential and electron density for proteinase K generated with the transferable aspherical atom model (TAAM) using the UBDB/MATTS data bank, the associated structural model of proteinase K and structure factors files.For the technical details on the method to generate the Fourier maps of electrostatic potential and electron density and for the theoretical background on the method, see (Kulik et al., 2022).The Fourier maps were generated using the atomic coordinates and B-factors from the model of proteinase K structure from Parengyodontium album (PDB ID 5i9s (Hattne et al., 2016)). The LSDB program (Volkov et al., 2004) was used to automatically assign the UBDB2018 atom type parameters (Kumar et al., 2019) to all atoms. DiSCaMB library, available at http://4xeden.uw.edu.pl/software/ (Chodkiewicz et al., 2018), was used to calculate the structure factors for X-ray diffraction for the TAAM with UBDB2018 parameters at given resolution and then to convert them to the structure factors for electron diffraction using the Mott-Bethe formula. The 3D Fourier maps of electrostatic potential (eTAAM) and electron density (xTAAM) were generated using the WinXD2016 package (Volkov et al., 2016) XDFOUR module at resolutions from 1 Å to 4 Å every 1 Å, and with voxel size 0.3 Å. The maps were generated in two versions: with or without taking into account the thermal smearing effects (denoted as with B or without B, respectively). The same set of B-factors was applied at every resolution in the Fourier maps that include the thermal smearing effects. The 3D Fourier maps deposited here were trimmed with a 3 Å margin around the protein and were not scaled. The associated structural model of proteinase K contains hydrogen atoms and B-factors as used for all the calculations.The structure factors files feature seven columns. The first three columns correspond to the reflection indices up to 1 Å resolution. Next, there are two sets of Fourier coefficients. The first two coefficients correspond to the real and imaginary parts of the TAAM structure factors, respectively. Additionally, we provide the second set of coefficients that correspond to the real and imaginary parts of the IAM structure factors. The structure factors files make it possible to generate the 3D Fourier maps of electrostatic potential and electron density calculated with TAAM or IAM, with or without taking into account the thermal smearing effects (denoted as with B or without B, respectively) at any given resolution worse than or equal to 1 Å.References:Kulik, M., Chodkiewicz, M. L. & Dominiak, P. M. (2022). Acta Crystallographica Section D, 78(8), 1010–1020.Hattne, J., Shi, D., de la Cruz, M. J., Reyes, F. E. & Gonen, T. (2016). J Appl Crystallogr, 49(Pt 3), 1029–1034.Volkov, A., Li, X., Koritsanszky, T. & Coppens, P. (2004). J. Phys. Chem. A, 108, 4283–4300.Kumar, P., Gruza, B., Bojarowski, S. A. & Dominiak, P. M. (2019). Acta Crystallogr A Found Adv, 75(Pt 2), 398–408.Chodkiewicz, M. L., Migacz, S., Rudnicki, W., Makal, A., Kalinowski, J. A., Moriarty, N. W., Grosse-Kunstleve, R. W., Afonine, P. V., Adams, P. D. & Dominiak, P. M. (2018). J Appl Crystallogr, 51(Pt 1), 193–199.Volkov, A., Macchi, P., Farrugia, L. J., Gatti, C., Mallinson, P., Richter, T. & Koritsanszky, T., (2016). XD2016 - a computer program package for multipole refinement, topological analysis of charge densities and evaluation of intermolecular energies from experimental and theoretical structure factors.</p
Europiella kiritshenkoi Kulik 1975
No full textEuropiella kiritshenkoi Kulik, 1975 Figures: 1 C, 3 C, 4 F–J Plagiognathus kiritshenkoi: Kulik, 1975: 587 (n. sp.); Kerzhner, 1979: 55 (desc., figs.); 1988 a: 855 (key) Europiella kiritshenkoi: Schuh et al., 1995: 390 (n. comb.); Schuh, 1995: 513 (cat.); Kerzhner and Josifov, 1999: 345 (cat.). Diagnosis. Generally recognized by its large body; usually greenish coloration; large black spot on antennal segment I, and segment II with basal 1 / 2 or 1 / 3 region black; length of segment II nearly equal to length of metafemora; short labium reaching apex of mesocoxae; yellowish metafemora ventrally with spots as in figure 3 C. Male genitalia (Fig. 4 G–J). Endosoma: Shape S–like, completely twisted at mesial region, apical processes curved, the short one apically curved as a hook in figure 4 J. Phallotheca: Broad, short and apically narrow as in figure 4 G. Left paramere: As in figure 4 H. Right paramere: As in figure 4 I. Female genitalia (Fig. 4 F). Bursa copulatrix with semi–sclerotized plates centrally, and sclerotized rings somewhat oval. Measurements. (5 ♂ / 5 ♀). Body length 4.04–4.67 / 4.43–4.62; head width across eyes 0.84–0.89 / 0.86–0.91; vertex width 0.45–0.50 / 0.42–0.54; lengths of antennal segments I–IV: 0.33–0.36, 1.45–1.65, 1.00– 1.17, 0.49–0.59 / 0.31–0.40, 1.46–1.55, 0.98–1.15, 0.57–0.64; total length of labium 1.06–1.26 / 1.21–1.28; mesal pronotal length 0.60–0.66 / 0.55–0.65; basal pronotal width 1.25–1.31 / 1.32–1.43; width across hemelytron 1.55–1.71 / 1.64–1.73; and lengths of metafemur, tibia and tarsus: 1.50–1.62, 2.45–2.58, 0.56–0.71 / 2.23–2.53, 0.61–0.68, 0.59–0.66. Specimens examined. South Korea: Gangwon–do: 7 ♂, 17 ♀, Wonju–si, Munmak, 27.v. 2009, on Artemisia sp. R.K. Duwal and S. Jung; 49 ♂, 42 ♀, same data as above except date, 27.v. 2009. Gyeonggi–do: 1 ♀, Yangpyeong–gun, 11.vi. 2009, on light trap, same collectors. Distribution. China, Korea *, Russia. Host. Artemisia vulgaris L. (Asteraceae) [Kulik, 1975]. Remarks. A large number of Europiella kiritshenkoi were aggregating on Artemisia sp. along a river and a few were collected in a light trap.Published as part of Duwal, Ram Keshari, Jung, Sunghoon & Lee, Seunghwan, 2014, Review of Europiella Reuter (Hemiptera: Heteroptera: Miridae: Phylinae: Phylini) from Korea, with a description of a new genus, pp. 383-393 in Zootaxa 3795 (3) on pages 387-388, DOI: 10.11646/zootaxa.3795.3.9, http://zenodo.org/record/22553
Pherolepis Kulik 1968
No full textPherolepis Kulik, 1968 Pherolepis Kulik 1968: 140. Type species: Pherolepis aenescens (Reuter, 1901) Diagnosis: Body broad and stout, weakly ovate; both male and female macropterous with membrane weakly declining; frons and clypeus more or less protuberant beyond anterior margin of eyes; posterior margin of vertex forming a complete carina; mandibular and maxillary plate rather broad; labium stout, at least reaching posterior margin of mesocoxae; pronotum broadly trapeziform with almost straight lateral margin; scutellum flattened, weakly swollen mesially; hemelytron rather broad and flattened, the corium covered with appressed or recumbent simple setae and scalelike or sericeous, appressed, curved and shining setae. Coloration of dorsal body usually brown, castaneous or almost black, sometimes reddish especially on lateral surface. Pherolepis are most similar in body appearance and dorsal coloration to Druthmarus Distant (1909) and Hypseloecus Reuter (1891), but could be separated from Druthmarus by never strongly enlarged antennal segment II, from Hypseloecus by lacking patches of scalelike setae on pronotum, propleuron and the whole abdominal surface. The structure of male genitalia in Pherolepis is closest to that of Pilophorus, whereas Pilophorus are more or less ant-mimetic and the scalelike setae on hemelytron always in the form of two transverse bands or several distinct patches. Male genitalia: Vesica L-shaped, more or less curved, never twisted, apically with an elongate spicule and a broad membrane, mesially with a distinctive, lanceolate projection; gonopore less developed; left paramere conventional phyline; right paramere lanceolate, leaf-shaped; phallotheca sclerotized, beaklike apically. Female genitalia: Bursa copulatrix rounded; sclerotized rings large, weakly quadrangular; vestibulum small, basal margin weakly enlarged with remainder tubular and curved; lateral oviduct tubular and slender, sometimes elongate; accessory gland forming a weakly sinuate tube. Hosts: Four species, P. a e n e s c e n s, P. amplus, P. fasciatus and P. kiritshenkoi are recognized to feed on Salix (Salicaceae) and Ulmus (Ulmaceae) (Kerzhner, 1970), but nothing is known of their habits. Baoying Qi (1996) noted that P. amplus had been predaceous-phytophagous when he summarized the predatory Mirids from Nei Mongol Autonomous Region of China. But he did not point out the prey. I collected specimens of P. robustus sp. nov. from a Pinus sp. where they had been feeding on the needles and buds. Distribution: China, Far East of the USSR, Mongolia and Japan. Note: Kerzhner (1970, 1988) described the hemelytron of Pherolepis amplus Kulik and P. kiritshenkoi (Kerzhner) covered with silvery scales. But according to the examination of related specimens and scanning electron micrographs, we consider that the “silvery scales” of the two species should be defined as sericeous setae, which are strongly shining and weakly flattened. Whereas slivery scales or scalelike setae which scattered on hemelytron of P. aenescens (Reuter) and P. fasciatus (Kerzhner) are silvery, distinctly flattened.Published as part of Zhang, Xu & Liu, Guo-Qing, 2009, Revision of the pilophorine plant bug genus Pherolepis Kulik, 1968 (Hemiptera: Heteroptera: Miridae: Phylinae), pp. 1-20 in Zootaxa 2281 on page 3, DOI: 10.5281/zenodo.19118
Superconductivity in ultrasmall metallic particles
No full textChapter 25Recent single electron transport experiments in nanometer size samples renewed the question about the lower limits of the size of superconductors, and the crossover from superconducting to normal state. In order to give answers to these questions, a pairing Hamiltonian for fixed number of particles is studied including the degeneracy of levels around the Fermi energy. For d-fold degenerate states we find that the ratio of two successive parity parameters Δ p is nearly 1 + l/d
Datasets and scripts for pseudosymmetry and local coordinate system analysis of atoms and atom types in MATTS2021
No full textThe repository contains datasets and scripts related to the analysis of electron density pseudosymmetry of atoms and atom types in the MATTS2021 data bank (Jha et al., 2022; Rybicka et al., 2022), evaluated for many different local coordinate system (LCS) types and orientations.Electron density pseudosymmetry was assigned based solely on multipole parameters (κ, κ′, Pval, and Plm) using symmetry selection rules (Kurki-Suonio, 1977), first at the level of individual LCS orientations, then per LCS type, and lastly as a final symmetry for each atom and atom type. Each symmetry, together with its associated LCS orientation, leads to a specific set of multipolar function that should vanish, i.e. their populations (Plm values) should be equal to zero (Kurki-Suonio, 1977). The provided files include symmetry assignments, statistical summaries, custom Bash and Python scripts, visualizations of parameter distributions, and comparisons of pseudosymmetry assignments between atoms, atom types, and symmetries in MATTS2021.The refinement of the multipole model for model molecules was performed using the same set of crystal structures and the same general procedure as that used to construct the MATTS2021 data bank (Jha et al., 2022), with modifications applied at the stage of multipole model refinement when symmetry constraints were imposed on refined parameters. Two distinct datasets of refined multipolar models were created: one resulting from refinements with the original symmetry constraints used in the construction of the MATTS2021 data bank (ref-SC), and another from refinements with no symmetry constraints (ref-NSC). Removing symmetry constraints allows all Plm to be populated.The primary data used for the determination of electron density pseudosymmetry consist of multipole model parameters calculated for atoms and atom types belonging to 14 topological subgroups. These subgroups are defined based on (a) the number of first neighbors and planarity, which together define a topological group (4n, 3n, 3p, 2p, or 1p), and (b) the chemical element (C, N, O, F, P, S, Cl, Br). Thus, the 14 topological subgroups are: 4n-C, 4n-N, 4n-P, 4n-S, 3n-N, 3p-C, 3p-N, 2p-N, 2p-O, 2p-S, 1p-F, 1p-Cl, and 1p-Br. Files specific to each topological group or subgroup include the group or subgroup name in the filename. The term “1p-halogens” refers to the combined set of 1p-F, 1p-Cl, and 1p-Br.For each subgroup, a universal atom type definition was created manually. These definitions were generalized with respect to neighbors, ring presence, and ring size, only planarity of the central atom was explicitly defined. This approach ensured that all atoms fitting a given subgroup, including both recognized (i.e., those with corresponding atom types in MATTS2021) and unrecognized (i.e., those without such atom types) ones, were identified in model molecules. Subsequently, topological-group-specific Bash scripts (1_make-definitions-{group}.bash, provided in /scripts/LCS/) generated new definitions of universal atom types for all considered LCS orientations, producing .txt files as output. These .txt files are provided in the /universal-definitions directory.The bankMaker utility from the DiSCaMB library (Chodkiewicz et al., 2018), a local Bash script ROTATE.bash (provided in the /scripts/LCS directory), and a dataset of refined multipolar models (ref-SC or ref-NSC) were used to calculate multipole parameters for every considered LCS orientation for each atom. For atom types, the same procedure was applied, but using the original MATTS2021 data bank atom type definitions in an unchanged order, provided in files generated by subgroup-specific local Bash scripts 2_make-little-banks-{subgroup}.bash (located in /scripts/LCS), instead of the universal atom type definitions. In both cases (atoms and atom types), all symmetries in the atom type definitions were set to “no”, preventing the enforcement of any symmetry higher than 1 and enabling all multipolar functions to be populated.The resulting sets of multipole parameters were generated for all LCS orientations and combined into subgroup-specific files for further analysis using local Bash and Python scripts (3_get-data.bash and 4_make-csv.py, provided in /scripts/LCS). The following subgroups were included in the subsequent analysis: 4n-C, 3n-N, and 3p-N for ref-SC; and 4n-C, 4n-N, 4n-P, 4n-S, 3n-N, 3p-C, 3p-N, 2p-N, 2p-O, 2p-S, and 1p-halogens (combined 1p-F, 1p-Cl, and 1p-Br) for ref-NSC. Files for 4n-C, 3n-N, and 3p-N indicate the refinement strategy used (ref-SC or ref-NSC) in their filenames. For the remaining subgroups, this information is not indicated, as ref-NSC is the default. A detailed description of the purpose and usage of each of the aforementioned scripts is provided in the read_me file in the /scripts/LCS directory.To assign pseudosymmetry based on the generated multipole parameters, it was necessary to determine when Plm values could be approximated as zero. For this purpose, zero-value thresholds were introduced and determined automatically using Gaussian Mixture Model (GMM) analysis (Zhuang et al., 1996) of Plm distributions. A custom Python script, gmm_threshold_analysis.py (provided in the /scripts/GMM directory), performed the analysis separately for each subgroup by automatically selecting the optimal number of Gaussian components (from 1 to 6 for each Plm parameter derived from ref-NSC atoms), calculating their weights, and identifying the dominant component. Plm parameters for which the mean of the dominant Gaussian component was greater than or equal to three times its standard deviation were excluded, as they were considered significantly different from zero. For each subgroup and LCS type, this procedure generated three outputs: histogram plots (*.png) showing Plm distributions with Gaussian fits; all_Plm_*.txt files containing statistics for the dominant Gaussian component for each Plm; and filtered_Plm_*.txt files including only the dominant Gaussian components used to define the zero-value thresholds. These files are available in the /GMM-analysis directory. A detailed description of the usage of the gmm_threshold_analysis.py script is provided in the read_me file in the /scripts/GMM directory.Finally, the generated multipole parameters and the established zero-value thresholds were used to assign electron density pseudosymmetry at the level of individual LCS orientations, per LCS type, and ultimately as a final symmetry for each atom and atom type. This stage employed numerous custom Bash and Python scripts, some of which are group- or subgroup-specific. These scripts are provided in the /scripts/PSEUDOSYMMETRY directory. A short description of the purpose of each script is given in the read_me file in the main directory, while more detailed usage instructions are provided in the read_me file in the /scripts/PSEUDOSYMMETRY directory.The /atoms-and-atom-types-data directory contains *.ods files with atom- and atom type-level data for each subgroup (as indicated by the filenames), including multipole model parameters and pseudosymmetry assignments across all considered LCS orientations. These files were created manually by combining information obtained from the outputs of the Bash and Python scripts from /scripts/PSEUDOSYMMETRY at various stages of the analysis and interpretation. Detailed information about the contents of the *.ods files, including descriptions of each sheet and column, is provided in a read_me file in the main folder.References:Chodkiewicz, M. L., Migacz, S., Rudnicki, W., Makal, A., Kalinowski, J. A., Moriarty, N. W., Grosse-Kunstleve, R. W., Afonine, P. V., Adams, P. D.; Dominiak, P. M. (2018). J. Appl. Crystallogr. 51, 193–199.Jha, K. K., Gruza, B., Sypko, A., Kumar, P., Chodkiewicz, M. L.; Dominiak, P. M. (2022). J. Chem. Inf. Model. 62, 3752–3765.Kurki-Suonio, K. (1977). Isr. J. Chem. 16, 115–123.Rybicka, P. M., Kulik, M., Chodkiewicz, M. L.; Dominiak, P. M. (2022). J. Chem. Inf. Model. 62, 3766–3783.Zhuang, X., Huang, Y., Palaniappan, K.; Zhao, Y. (1996). IEEE Trans. Image Process. 5, 1293–1302.</p
The multiple category problem: Lateral inhibition in the hiring process
No full textResearch has demonstrated that organizational decision makers use categories and
associated stereotypes to make hiring decisions. But what happens when a job
applicant can be categorized in multiple ways? We use the social cognition literature
to develop a model of category activation and inhibition in the hiring process. The
model explains how situational and individual-difference variables influence which
category will dominate the decision maker’s impression of the job candidate and exert
the greatest influence on the hiring decision
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Ischemia but not anoxia evokes vesicular and Ca2+-independent glutamate release in the dorsal vagal complex in vitro
No full textWhole cell recordings of fura-2 dialyzed vagal neurons of brain stem slices were used to monitor interstitial glutamate accumulation within the dorsal vagal complex. Anoxia produced a sustained outward current (60 pA) and a moderate [Ca2+](i) rise (40 nM). These responses were neither mimicked by [1S,3R]-1-aminocyclo-pentane-1,3-dicarboxylic acid nor affected by Ca2+-free solution, 6-cyano-7-nitroquino-xaline-2,3-dione (CNQX), 2-amino-5-phosphonovalerate (APV), or tetrodotoxin. Anoxia or cyanide in glucose-free saline (in vitro ischemia) as well as ouabain or iodoacetate elicited an initial anoxia-like [Ca2+](i) increase that turned after several minutes into a prominent Ca2+ transient (0.9 mu M) and inward current (-1.8 nA). APV plus CNQX (plus methoxyverapamil) inhibited this inward current as well as accompanying spontaneous synaptic activity, and reduced the secondary [Ca2+](i) rise to values similar to those during anoxia. Each of the latter drugs delayed onset of both ischemic current and prominent [Ca2+](i) rise by several minutes and attenuated their magnitudes by up to 40%. Ca2+-free solution induced a twofold delay of the ischemic inward current and suppressed the prominent Ca2+ increase but not the initial moderate [Ca2+](i) rise. Cyclopiazonic acid or arachidonic acid in Ca2+-free saline delayed further the ischemic current, whereas neither inhibitors of glutamate uptake (dihydrokainate, D,L-threo-beta-hydroxyaspartate, L-transpyrrolidone-2,4-dicarboxylate) nor the Cl- channel blocker 5-nitro-2-(3-phenylpropyl-amino) benzoic acid had any effect. In summary, the response to metabolic arrest is due to activation of ionotropic glutamate receptors causing Ca2+ entry via N-methyl-D-aspartate receptors and voltage-activated Ca2+ channels. An early Ca2+-dependent exocytotic phase of ischemic glutamate release is followed by nonvesicular release, not mediated by reversed glutamate uptake or Cl- channels. The results also show that glycolysis prevents glutamate release during anoxia
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