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Several Possibilities (several + possibility)
Selected AbstractsP - and S -wave reflectors in D, beneath southeast AsiaGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 2 2009Jeremy W. Chaloner SUMMARY Earthquakes from the South Pacific region recorded at the Kyrgyz Seismic Network (KNET) and the GHENGIS network (both part of the Tien Shan Continental Dynamics study) have been analysed to search for evidence of reflections from the D, region. The reflection points of this source,receiver combination are in a seismically fast area beneath Southeast Asia. Employing several array methods, we find evidence for reflections from a D, reflector in both P and S waves. The reflector depth generally agrees for both wave types. There is some evidence for a second, deeper reflector in this region; migrating the data suggests a lower-seismic reflector beneath the northeastern end of the study region. The waveforms of P and S waves imply that the upper reflector has a negative impedance contrast for P but a positive impedance contrast for S. Several possibilities are discussed for generating the observed reflector(s), with the post-perovskite phase transition in combination with a cold slab being the preferred explanation. [source] Perforated shell and stone objects from SharmARABIAN ARCHAEOLOGY AND EPIGRAPHY, Issue 2 2003Diane Barker A group of six shell and four stone perforated objects is examined with a view to determining their function. Several possibilities are suggested as a result of a number of parallels in southeastern Arabia. [source] The Origin of Aromaticity: Important Role of the Sigma Framework in BenzeneCHEMPHYSCHEM, Issue 9 2004Borislav Kova Abstract The physical nature of aromaticity is addressed at a high ab initio level. It is conclusively shown that the extrinsic aromatic stabilization energy of benzene E(ease)B, estimated relative to its linear polyene counterpart(s), is very well-reproduced at the Hartree,Fock (HF) level. This is a consequence of the fact that the contributions arising from the zero-point vibrational energy (ZPVE) and electron correlation are rather small. More specifically, they yield together 2.0 kcal,mol,1to the destabilization of benzene. A careful scrutiny of the HF energies by virial theorem shows further that the kinetic energies of the , and , electrons E(T) and E(T) are strictly additive in the gauge linear zig-zag polyenes, which also holds for their sum Et(T)HF. This finding has the important corollary that E(ease)Bis little dependent on the choice of the homodesmic reactions involving zig-zag polyenes. A detailed physical analysis of the ,- and ,-electron contributions to extrinsic aromaticity requires explicit introduction of the potential energy terms Vne, Vee, and Vnn, which signify Coulomb interactions between the electrons and the nuclei. The Veeterm involves repulsive interaction V between the , and , electrons, which cannot be unequivocally resolved into , and , contributions. The same holds for the Vnnenergy, which implicitly depends on the electron density distribution via the Born,Oppenheimer (BO) potential energy surface. Several possibilities for partitioning V and Vnnterms into , and , components are examined. It is argued that the stockholder principle is the most realistic, which strongly indicates that E(ease)Bis a result of favorable , -framework interactions. In contrast, the ,-electron framework prefers the open-chain linear polyenes. [source] Approximate imposition of boundary conditions in immersed boundary methodsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 11 2009Ramon Codina Abstract We analyze several possibilities to prescribe boundary conditions in the context of immersed boundary methods. As basic approximation technique we consider the finite element method with a mesh that does not match the boundary of the computational domain, and therefore Dirichlet boundary conditions need to be prescribed in an approximate way. As starting variational approach we consider Nitsche's methods, and we then move to two options that yield non-symmetric problems but that turned out to be robust and efficient. The essential idea is to use the degrees of freedom of certain nodes of the finite element mesh to minimize the difference between the exact and the approximated boundary condition. Copyright © 2009 John Wiley & Sons, Ltd. [source] Comparison of second-order orbital-dependent DFT correlation functionalsINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 12 2008Ireneusz Grabowski Abstract The choice of the orbital-dependent second-order correlation functional plays the prime role in the description of the correlation effects in orbital-dependent DFT calculations. Using second-order perturbation theory we were able to derive the simplest orbital-dependent correlation functional, but even at this lowest correlation level, we had several possibilities to define it. Applications of different second-order correlation functionals for the atomic as well as molecular systems are presented. The ab initio DFT-type OEP2 functionals based on Møller-Plesset or semicanonical partitioning (OEP2-sc) are compared with those based on Epstein-Nesbet type partitioning, showing that the latter ones can fail in more difficult molecular problems, e.g., the Be dimer potential curve. We show that currently the best performing orbital-dependent second-order correlation functional is the OEP2-sc one. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008 [source] Videotaped recording as a method of participant observation in psychiatric nursing researchJOURNAL OF ADVANCED NURSING, Issue 5 2000Eila Latvala RN PhD Videotaped recording as a method of participant observation in psychiatric nursing research This paper describes videotaped recording as a data collection method when conducting participant observation in a psychiatric nursing study. The videotaped episodes were part of the daily life of psychiatric nursing in a hospital environment. The advantages and limitations of using videotaped recording in nursing research will be discussed. This paper is based on two studies. The data consisted of 21 videotaped episodes of nursing report sessions or interdisciplinary team meetings in the psychiatric clinic of a university hospital. The participants consisted of patients, their significant others, nurses, doctors, social workers and physiotherapists. All videotaped material was transcribed verbatim. An essential advantage of videotaping is that most potentially useful interaction and behaviour can be captured. The advantage in terms of the credibility of videotaping was that the investigator was able to review the same videotaped situations again and again. Videotaped material is rich and provides several possibilities for analysing the data. In these studies data and source triangulation enabled the researchers to reduce personal influence on the results. The investigator must also be aware of the limitations concerning this method. The most essential limitations are mechanical problems and the influence of videotaping on behaviour. Careful ethical considerations are important concerning personal privacy, informed consent and respect for the self-determination of psychiatric patients. [source] Enamel matrix derivative exhibits angiogenic effect in vitro and in a murine modelJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 8 2003Kuo Yuan Abstract Objectives: Angiogenesis is one of the most critical events in the wound healing process. Any increase in angiogenesis could result in more rapid and complete healing. A recent study found that enamel matrix derivative (EMD) could accelerate early periodontal wound healing. We wanted to clarify whether EMD caused an angiogenic effect and, thus, possibly enhanced wound healing. Methods: We performed in vitro proliferation and chemotaxis assays on human umbilical vein endothelial cell (HUVEC) cultures, and a tissue culture assay using blood vessel fragments in fibrin gel. Collagen membranes soaked with EMD were implanted subcutaneously in mice to test the in vivo angiogenic effect. Results: While there were no significant differences between the negative control and EMD groups in the proliferation assay, EMD treatment did exhibit a significantly greater dose-dependent chemotactic effect on HUVEC than control group treatments. The tissue culture in fibrin gel showed new blood vessel outgrowths in the EMD groups, but none in the negative control group. In the animal studies, significantly more endothelial cells were detected in the EMD group of mice. Conclusions: Our findings show that EMD does exhibit some angiogenic effects. However, the underlying molecules and mechanisms are still unidentified. We discuss several possibilities. Zusammenfassung Ziele: Die Angiogenese gehört zu den kritischsten Ereignissen bei der Wundheilung. Eine Erhöhung der Angiogenese könnte zu einer rascheren und kompletteren Wundheilung führen. Kürzlich zeigte eine Studie, dass Schmelzmatrixderivate (EMD) die frühe parodontale Wundheilung beschleunigen könnte. Wir wollten klären, ob EMD einen angiogenetischen Effekt verursacht und dies möglicherweise die Wundheilung verbessert. Methoden: Wir führten in vitro Proliferations- und Chemotaxis-Assays an menschlichen Umbilicalvenen-Endothelzellen (HUVEC)Kulturen durch und studierten eine Gewebekultur unter Nutzung von Blutgefäßfragmenten in Fibringel. Kollagenmembranen mit EMD getränkt wurden subkutan in Mäuse implantiert, um den angiogenetischen Effekt in vivo zu testen. Ergebnisse: Während es keine signifikanten Differenzen zwischen den negativen Kontrollen und den EMD Gruppen in dem Proliferationsassay gab, zeigte die EMD Behandlung einen signifikant größeren, dosisabhängigen chemotaktischen Effekt auf HUVEC verglichen mit den Kontrollen. Die Gewebekultur im Fibringel zeigte neue Blutgefäßbildungen in den EMD-Gruppen, aber keine bei den Negativkontrollen. Bei den Tierstudien wurden signifikant mehr Endothelzellen in den EMD Mäusegruppen entdeckt. Schlussfolgerungen: Unsere Ergebnisse zeigen, dass EMD einige angiogenetische Effekte zeigt. Jedoch sind die zugrunde liegenden Moleküle und die Mechanismen noch nicht geklärt. Wir diskutieren verschiedene Möglichkeiten. Résumé Objectifs: L'Angiogenèse est un des plus critiques éléments lors du processus de cicatrisation. La moindre augmentation de l'angiogenèse peut entraîner une cicatrisation plus rapide et plus complète. Une récente étude a montré que les dérivés de la matrice amellaire (EMD) pouvait accélérer plus tôt la cicatrisation parodontale. Nous voulions clarifier la possible responsabilité de l'EMD dans l'angiogenèse et si oui, l'amélioration de la cicatrisation. Méthodes: Nous avons réalisé in vitro la prolifération et un essai de chimiotactisme sur des cultures de cellules endothéliales de la veine ombilicale humaine (HUVEC), et un essai de culture tissulaire en utilisant des fragments de vaisseaux sanguins dans un gel de fibrine. Des membranes de collagène gorgées d'EMD furent implantées en sous-cutanée chez des souris pour tester l'effet angiogénique in vivo. Résultats: Bien qu'il n'y eut pas de différences significatives entre le contrôle négatif et le groupe EMD pour le test de prolifération, le traitement par EMD présentait un effet chimiotactique dose- dépendant significativement plus élevé sur les HUVEC. La culture tissulaire sur gel de fibrine présentait une surcroissance de nouveaux vaisseaux sanguins pour le groupe EMD, mais pas dans le groupe contrôle. Plus de cellules endothéliales furent en outre détectées lors de l'étude animale, pour le groupe de souris traitées par EMD. Conclusions: Nos données montrent que l'EMD présente quelques effets angiogéniques. Cependant, les molécules et les mécanismes responsables ne sont toujours pas identifiés. Nous discutons quelques possibilités. [source] Correlations between clinical and historical variables, and cerebral structural variables in people with mild intellectual disability and schizophreniaJOURNAL OF INTELLECTUAL DISABILITY RESEARCH, Issue 2 2001T. L. Sanderson Abstract The increased prevalence of schizophrenia in the population with mildly intellectual disability (ID) remains unexplained. The present study explores several possibilities by examining historical/clinical findings in relation to structural neuroimaging findings in three groups: (1) comorbid mild ID and schizophrenia; (2) schizophrenia alone; and (3) mild ID alone. Information about clinical and historical variables was obtained from 101 subjects (39 with comorbidity, 34 with schizophrenia and 28 with mild ID), out of whom 68 (23, 25 and 20, respectively) had had a cerebral magnetic resonance imaging (MRI) scan. Although a number of significant correlations exist between clinical variables and structural MRI abnormalities in all three groups, no clearly predictive inter- or between-group differences emerged. More striking was the finding that showed small amygdalo-hippocampal size to be associated with a history of central nervous system injury, especially meningitis. These findings provide support for the view that cognitive impairment and comorbid psychosis can result from a common cause, such as meningitis or obstetric complications, possibly interacting with other factors, such as family history. [source] Ehlers,Danlos Syndrome and Anorexia Nervosa: A Dangerous Combination?PEDIATRIC DERMATOLOGY, Issue 3 2007Stacia C. Miles M.D. Although prior occurrences of pneumomediastinum and visceral perforations have been reported in adolescents with isolated anorexia nervosa or Ehlers,Danlos syndrome, to our knowledge this is the first instance to be noted in a patient with both conditions. We explore several possibilities regarding the etiology of his mediastinal air, but ultimately conclude that it was the existence of Ehlers,Danlos syndrome in the presence of anorexia nervosa that led to the development of this dangerous condition. [source] Treatment of Carbon Tetrafluoride with Gas DischargesPLASMA PROCESSES AND POLYMERS, Issue 7-8 2007Gerhard J. Pietsch Abstract Waste gases from semiconductor industry contain perfluorocarbons, which cause global warming and therefore should be removed. There are several possibilities to do this, for example the treatment of the gas by thermal and non-thermal plasmas, as well as by heating. In model gases containing up to 10,000 ppm CF4, destruction removal efficiencies of nearly 100% have been reached at atmospheric pressure using dielectric barrier and arc discharges. In order to reach high values, the dissociation products of CF4 must be bonded by reaction partners such as SiO2, CaO or H2O. [source] REVIEW ARTICLE: The Unique Properties of Uterine NK CellsAMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 6 2010Irit Manaster Citation Manaster I, Mandelboim O. The unique properties of uterine NK cells. Am J Reprod Immunol 2009 Abstract Natural killer (NK) cells are lymphocytes of the innate immunity system that are able to kill various hazardous pathogens and tumors. However, it is now widely accepted that NK cells also possess non-destructive functions, as has been demonstrated for uterine NK cells. Here, we review the unique properties of the NK cells in the uterine mucosa, prior to and during pregnancy. We discuss the phenotype and function of mouse and human endometrial and decidual NK cells and suggest that the major function of decidual NK cells is to assist in fetal development. We further discuss the origin of decidual NK cells and suggest several possibilities that might explain their accumulation in the decidua during pregnancy. [source] Atomic displacements at and order of all phase transitions in multiferroic YMnO3 and BaTiO3ACTA CRYSTALLOGRAPHICA SECTION B, Issue 4 2009S. C. Abrahams Coordinate analysis of the multiple phase transitions in hexagonal YMnO3 leads to the prediction of a previously unknown aristotype phase, with the resulting phase-transition sequence: P63,cm,(e.g.) ,P63cm,P63/mcm,P63/mmc,P6/mmm. Below the Néel temperature TN, 75,K, the structure is antiferromagnetic with the magnetic symmetry not yet determined. Above TN the P63cm phase is ferroelectric with Curie temperature TC, 1105,K. The nonpolar paramagnetic phase stable between TC and ,,1360,K transforms to a second nonpolar paramagnetic phase stable to ,,1600,K, with unit-cell volume one-third that below 1360,K. The predicted aristotype phase at the highest temperature is nonpolar and paramagnetic, with unit-cell volume reduced by a further factor of 2. Coordinate analysis of the three well known phase transitions undergone by tetragonal BaTiO3, with space-group sequence R3m,Amm2 ,P4mm,Pmm, provides a basis for deriving the aristotype phase in YMnO3. Landau theory allows the I , II, III , IV and IV , V phase transitions in YMnO3, and also the I , II phase transition in BaTiO3, to be continuous; all four, however, unambiguously exhibit first-order characteristics. The origin of phase transitions, permitted by theory to be second order, that are first order instead have not yet been thoroughly investigated; several possibilities are briefly considered. [source] | |||||||||||||