177,057 research outputs found
Many-particle effects in adsorbed magnetic atoms with easy-axis anisotropy: the case of Fe on the CuN/Cu(100) surface
No full textWe study the effects of the exchange interaction between an adsorbed magnetic atom with easy-axis magnetic anisotropy and the conduction-band electrons from the substrate. We model the system using an anisotropic Kondo model and we compute the impurity spectral function, which is related to the differential conductance (dI / dV) spectra measured using a scanning tunneling microscope. To make contact with the known experimental results for iron atoms on the CuN/Cu(100) surface (Hirjibehedin et al 2007 Science 317 1199), we calculated the spectral functions in the presence of an external magnetic field of varying strength applied along all three spatial directions. It is possible to establish an upper bound on the coupling constant J : in the range of the magnetic fields for which the experimental results are currently known (up to 7 T), the low-energy features in the calculated spectra agree well with the measured dI / dV spectra if the exchange coupling constant J is at most half as large as that for cobalt atoms on the same surface. We show that for an even higher magnetic field (between 8 and 9 T) applied along the 'hollow direction', the impurity energy states cross, giving rise to a Kondo effect which takes the form of a zero-bias resonance. The coupling strength J could be determined experimentally by performing tunneling spectroscopy in this range of magnetic fields. On the technical side, the paper introduces an approach for calculating the expectation values of global spin operators and all the components of the impurity magnetic susceptibility tensor (including the out-of-diagonal ones) in numerical renormalization group (NRG) calculations with no spin symmetry. An appendix contains a density functional theory (DFT) study of the Co and Fe adsorbates on the CuN/Cu(100) surface: we compare magnetic moments, as well as orbital energies, occupancies, centers and spreads, by calculating the maximally localized Wannier orbitals of the adsorbates.Slovenian Research Agency (ARRS) [Z1-2058]; DFG [SFB 602
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Design, synthesis and evaluation of heterocyclic compounds with potential antimicrobial activity VII
No full textCharles University, Faculty of Pharmacy in Hradec Králové Candidate: Pavlína Sokolová Mentor: doc. PharmDr. Jan Zitko, Ph.D. Consultant: Mgr. Marek Kerda, Ph.D. Thesis Title: Design, synthesis and evaluation of heterocyclic compounds with potential antimicrobial activity VII Antimicrobial resistance is a serious global threat and requires the development of new active substances. In this work, a series of 16 chlorianted 2-phenyl-N-(pyrazinyl)acetamides and 2-phenyl-N-(pyridyl)acetamides, derived from 4-hydroxyphenylacetic acid and their acetylated derivatives, were synthesized and characterized. The aim was to specifically modify them, namely the introductions of a methylene bridge and verify its influence on biological activity. All substances were tested against selected mycobacterial, bacterial and fungal strains by determining the MIC. In this thesis, I present only the results of testing on mycobacteria, as the other parts are still in the testing phase. The core structure of new potential antimicrobial agents based on 2-phenyl-N-(pyrazinyl)acetamides a 2-phenyl-N-(pyridyl)acetamides. The methylene bridge is highlighted; the R substituent represents either a hydroxy or an acetoxy group, and the chlorine atom is attached at various positions of the heterocyclic ring. The results of biological..
Design, synthesis and evaluation of heterocyclic compounds with potential antimicrobial activity VII
No full textCharles University, Faculty of Pharmacy in Hradec Králové Candidate: Pavlína Sokolová Mentor: doc. PharmDr. Jan Zitko, Ph.D. Consultant: Mgr. Marek Kerda, Ph.D. Thesis Title: Design, synthesis and evaluation of heterocyclic compounds with potential antimicrobial activity VII Antimicrobial resistance is a serious global threat and requires the development of new active substances. In this work, a series of 16 chlorianted 2-phenyl-N-(pyrazinyl)acetamides and 2-phenyl-N-(pyridyl)acetamides, derived from 4-hydroxyphenylacetic acid and their acetylated derivatives, were synthesized and characterized. The aim was to specifically modify them, namely the introductions of a methylene bridge and verify its influence on biological activity. All substances were tested against selected mycobacterial, bacterial and fungal strains by determining the MIC. In this thesis, I present only the results of testing on mycobacteria, as the other parts are still in the testing phase. The core structure of new potential antimicrobial agents based on 2-phenyl-N-(pyrazinyl)acetamides a 2-phenyl-N-(pyridyl)acetamides. The methylene bridge is highlighted; the R substituent represents either a hydroxy or an acetoxy group, and the chlorine atom is attached at various positions of the heterocyclic ring. The results of biological...Univerzita Karlova, Farmaceutická fakulta v Hradci Králové Řešitel: Pavlína Sokolová Školitel: doc. PharmDr. Jan Zitko, Ph.D. Konzultant: Mgr. Marek Kerda, Ph.D. Název diplomové práce: Návrh, syntéza a hodnocení heterocyklických sloučenin s potencionální antimikrobní aktivitou VII Antimikrobiální rezistence představuje vážnou celosvětovou hrozbu a vyžaduje vývoj nových účinných látek. V rámci této práce byla syntetizována a charakterizována série 16 chlorovaných 2-fenyl-N-(pyrazinyl)acetamidů a 2-fenyl-N-(pyridyl)acetamidů, odvozených z kyseliny 4-hydroxyfenyloctové a jejich acetylovaných derivátů. Cílem byla konkrétní modifikace, a to zavedení methylenového můstku a ověření jeho vlivu na biologickou aktivitu. Všechny látky byly testovány proti vybraným mykobakteriálním, bakteriálním a mykotickým kmenům stanovením MIC. V diplomové práci uvádím pouze výsledky testování na mykobakterie, protože ostatní části jsou dosud ve fázi testování. Základní struktura nových potenciálních antimikrobiálních látek na bázi 2-fenyl-N-(pyrazinyl)acetamidů a 2-fenyl-N-(pyridyl)acetamidů. Zvýrazněn je methylenový můstek, substituent R představuje buď hydroxy nebo acetoxyskupinu a atom chloru je navázán v různých pozicích heterocyklického jádra. Výsledky biologického testování neprokázaly významnou aktivitu proti...Katedra farmaceutické chemie a farmaceutické analýzyDepartment of Pharmaceutical Chemistry and Pharmaceutical AnalysisFaculty of Pharmacy in Hradec KrálovéFarmaceutická fakulta v Hradci Králov
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Splitting of the Kondo resonance in anisotropic magnetic impurities on surfaces
No full textUsing the numerical renormalization group method, we study the splitting of the Kondo resonance by a magnetic field applied in different directions in the Kondo model for anisotropic magnetic impurities. Several types of magnetic anisotropy are considered: the XXZ exchange coupling anisotropy J(perpendicular to) not equal J(z), the longitudinal magnetic anisotropy DS(z)(2) and the transverse magnetic anisotropy E(S(x)(2) - S(y)(2)). In the spin-1/2 model with the XXZ exchange coupling anisotropy, we find very small direction dependence in the magnitude of the splitting. In the spin-3/2 model with the easy-plane (D > 0) anisotropy, we observe very unequal magnitudes with further differences between the x- and y-directions in the presence of an additional transverse anisotropy. A simple and rather intuitive interpretation is that the splitting is larger in magnetically soft directions. The magnitude of the splitting is directly related to the energy differences between spin states and it is only weakly modified by some multiplicative factor due to Kondo screening. The results for the S = 3/2 model are in good agreement with recent scanning tunneling spectroscopy studies of Co impurities adsorbed on CuN islands on Cu(100) surfaces (Otte A F et al 2008 Nat. Phys. 4 847)
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
Letter from R. R. Zellick, Assistant Trust Officer, Anglo California National Bank of San Francisco, to Joseph R. Goodman, October 2, 1942
No full textLetter from R. R. Zellick, Assistant Trust Officer at The Anglo California National Bank of San Francisco, to Joseph R. Goodman, regarding property owned by Dave Tatsuno. Zellick mentions a dispute between current tenants and Tatsuno, and that Tatsuno has asked Goodman to help locate trustworthy tenants.Personal correspondence, organizational records, government documents, publications, and other papers created or collected by Joseph R. Goodman documenting the forced removal and incarceration of Japanese Americans during World War II, as well as organized resistance to incarceration. Included in the collection are records of the Japanese Young Men's Christian Association and the Japanese American Citizens' League in San Francisco, including papers of the Japanese YMCA's executive secretary Lincoln Kanai; Sakai family papers; Goodman's correspondence to and from Japanese American incarcerees, organizations opposing forced removal and incarceration of Japanese Americans, the War Relocation Authority, and others; publications, photographs, and ephemera from the Topaz Relocation Center, where Goodman taught high school; War Relocation Authority records and publications; and newspaper clippings, pamphlets, and reports about forced removal and incarceration created by various government, religious, and civic organizations, in California and nationwide
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Determining the directions and characteristics of underground water flow in karst for the purpose of traffic routes construction: The case of the new Divača-koper railway line (SW Slovenia)
No full textThe new railway line between Divača and Koper/Capodistria in south-western Slovenia is being built, a part of which crosses the southern outskirts of the Classical Karst plateaux. It will run through two tunnels, the northern tunnel T1 (6.7 km long) and the southern T2 (6 km long), which partially cross karst aquifer system. A multi-tracer test with injections of fluorescent dyes uranine and naphthionate, bypassing the karst vadose zone, was carried out to define the directions and dynamics of the underground water flow. The main goals were better understanding of the complex hydrogeological conditions in the area and assessment of possible environmental impacts on the nearby water sources. With tracing of uranine injected into a nearby cave stream, the direction of flow from the northern T1 tunnel mainly towards the Reka-Timavo aquifer system and further towards the Timava/Timavo springs was proved. The peak velocities, as determined from the peaks of the tracer breakthrough curves, range from 29 m/h to 36 m/h. Through the wider and well-connected conduits of the Reka-Timavo system, the peak velocities can reach up to 88 m/h. The recov-ery of uranine in an intermediate cave, i.e., Jama 1 v Kanjad-ucah, amounted to approximately 74 %. The northern section of the southern T2 tunnel is a part of a wider bifurcation zone between the Osapska Reka and the Boljunec/Bagnoli springs, where peak flow velocities between 10 and 13 m/h have been determined by tracing of naphthionate injected into a borehole located in the line of the planned tunnel. It has been estimated that about 25 % of the injected naphthionate flew out through the Osapska Reka spring and about 5 % through the Boljunec/ Bagnoli springs. Based on this research, proper monitoring of any potential negative impacts of the new railway line will be made possible. The study presents an approach to better plan-ning of hazard control of traffic routes in complex and highly karstified rock settings
- …
