124 research outputs found

    Evidance for an Oxygen Diffusion Model for the Electric Pulse Induced Resistance Change Effect in Oxides

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    Electric pulse induced resistance (EPIR) switching hysteresis loops for Pr0.7Ca0.7MnO3 (PCMO) perovskite oxide films were found to exhibit an additional sharp "shuttle peak" around the negative pulse maximum for films deposited in an oxygen deficient ambient. The device resistance hysteresis loop consists of stable high resistance and low resistance states, and transition regions between them. The resistance relaxation of the "shuttle peak" and its temperature behavior as well as the resistance relaxation in the transition regions were studied, and indicate that the resistance switching relates to oxygen diffusion with activation energy about 0.4eV. An oxygen diffusion model with the oxygen ions (vacancies) as the active agent is proposed for the non-volatile resistance switching effect in PCMO.Comment: 7 pages, 5 figure

    Experimental and theoretical study of three interacting, closely-spaced, sharp-edged 60 deg delta wings at low speeds

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    Wind tunnel tests were conducted to determine the subsonic longitudinal aerodynamic characteristics of lifting configuration consisting of a 60 deg delta main wing with two smaller 60 deg delta wings (called sub-wings) attached underneath. The test was designed to determine the effects on lift, drag, and pitching moment due to various placement of the subwings in relation to the main wing. Test results indicate the increasing vertical separation between the main wing and the sub-wings produced the most significant results; a 23.1% increase in maximum lift coefficient, a reduction in drag coefficient at high lift coefficients, and an increase in longitudinal stability. Lateral separation of the sub-wings produced no significant changes. Placement of the sub-wings rearward increases the initial lift curve slope and maximum lift coefficient and also increase the longitudinal stability. Results of a computer study using a vortex lattice code supported the experimental conclusions

    Investigation of unusual mortalities of bottlenose dolphins along the mid-Texas coastal bay ecosystem during 1992

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    An investigation was conducted into the deaths of more than 220 bottlenose dolphins (Tursiops truncatus) that occurred within the coastal bay ecosystem of mid-Texas between January and May 1992. The high mortality rate was unusual in that it was limited to a relatively small geographical area, occurred primarily within an inshore bay system separated from the Gulf of Mexico by barrier islands, and coincided with deaths of other taxa including birds and fish. Factors examined to determine the potential causes of the dolphin mortalities included microbial pathogens, natural biotoxins, industrial pollutants, other environmental contaminants, and direct human interactions. Emphasis was placed on nonpoint source pesticide runoff from agricultural areas, which had resulted from record rainfall that occurred during the period of increased mortality. Analytical results from sediment, water, and biota indicated that biotoxins, trace metals, and industrial chemical contamination were not likely causative factors in this mortality event. Elevated concentrations of pesticides (atrazine and aldicarb) were detected in surface water samples from bays within the region, and bay salinities were reduced to <10 ppt from December 1991 through April 1992 due to record rainfall and freshwater runoff exceeding any levels since 1939. Prolonged exposure to low salinity could have played a significant role in the unusual mortalities because low salinity exposure may cause disruption of the permeability barrier in dolphin skin. The lack of established toxicity data for marine mammals, particularly dermal absorption and bioaccumulation, precludes accurate toxicological interpretation of results beyond a simple comparison to terrestrial mammalian models. Results clearly indicated that significant periods of agricultural runoff and accompanying low salinities co-occurred with the unusual mortality event in Texas, but no definitive cause of the mortalities was determined. (PDF file contains 25 pages.

    The role of empathy in psychoanalytic psychotherapy: A historical exploration

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    Empathy is one of the most consistent outcome predictors in contemporary psychotherapy research. The function of empathy is particularly important for the development of a positive therapeutic relationship: patients report positive therapeutic experiences when they feel understood, safe, and able to disclose personal information to their therapists. Despite its clear significance in the consulting room and psychotherapy research, there is no single, consensual definition of empathy. This can be accounted by the complex and multi-faceted nature of empathy, as well as the ambiguous and conflicting literature surrounding it. This paper provides a historical exploration of empathy and its impact on the therapeutic relationship across the most influential psychoanalytic psychotherapies: classic psychoanalysis, person-centered therapy and self-psychology. By comparing the three clinical schools of thought, the paper identifies significant differences in the function of transference and therapist’s role. Then, drawing on the different clinical uses of empathy, the paper argues that the earlier uses of empathy (most notably through Jaspers’ and Freud’s writings) are limited to its epistemological (intellectual or cognitive) features, whilst person-centered and self-psychology therapies capitalise on its affective qualities. Finally, the paper provides a rationale for further study of the overarching features of empathy in contemporary psychotherapy research

    Transits across a Cyclopentadienyl: Organic and Organometallic Haptotropic Shifts

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    references cited therein. (13) Electron acceptors which are also conjugated with the alkene r system will polarize the HOMO in the same directions as, but to a smaller extent than, Inductive acceptors.8 (14) There has been a suggestion that Me is an acceptor relative to H when attached to an sp3 carbon [C. A. Grob, Angew. Chem. lnt. Ed. Engl., 15, 569 (1976), and references cited therein]. The product ratio discussed here reflect this, but the IP changes do not. A subtle role of solvent may be involved. (15) J. Bastideand J. P. Maier, Chem. Phys., 12, 144 (1976 Li+, CUR+), the e component of which greatly stabilizes the most symmetrical q5 coordination. The lower the energy of the e acceptor set and the better the overlap with its Cp counterpart, the more are q2 and q5 stabilized relative to 7&apos;. In the case of XH3+ (X = C, Si, Ge, Sn) an e acceptor orbital moves to lower energy as one proceeds down the group, and this is responsible for the decreasing barrier for sigmatropic shifts in CpXH3. The XH2 case, which yields a number of interesting collapse structures, is analyzed in detail for X, a main group center. Contrast the interaction of a cyclopentadienide anion and a proton with the interaction of the same anion and a Mn(CO)3+ fragment. Both result in stable molecules: cyclopentadiene (1) and V~-C~M~( C O )~ (2). But what a difference in the equilibrium geometries of these end products of the interaction! If we focus our attention on the cyclopentadienide site where the interacting partner settles down, then the proton chooses a position near to one carbon of the ring, but the Mn(C0)3+ fragment sits directly over the center of the ring. The ramifications of this differential are the concern of this paper. We will examine the interaction of a cyclopentadienide (CsHs-, Cp) ion with an interacting group X, X = H+, CH3+, SiR3+, Mn(C0)3+, CH22f, CH2. The result will consist of some conclusions concerning the equilibrium geometry of CpX as well as the relative energetics of the various haptotropic reactions of this Consider the passage of the interacting group X across the face of a Cp molecule, moving as indicated in 3 in a plane parallel to the Cp ring. Let the distance d be a separation at which there is sizable interaction between the frontier orbitals of X and the Cp a system. For a surface so constrained the asymmetric unit that need be calculated consists of the shaded area in 4, and two of the three boundaries of that area are contained in a transit along a line shown in projection in 5. Mirror symmetry is maintained at all points. The numbers nq shown along that line are convenient labels invoking a connection to the inorganic 7&quot; notation* for denoting an approximate coordination geometry. In order to avoid confusion with structure numbers and ring carbon numbers, we have labeled the various sites along the transit line as 17, 217, . . . , 57. The site labeled 17, or some geometry near it, corresponds to or simple u interaction, such as we have in the collapse product cyclopentadiene. The 7IS site 57 is where one better come up with maximum stabilization for X = Mn(C0)3+. The site labeled 27 positions X over the center of a bond, and obviously will describe the important transition state region for a sigmatropic shift of a system like cyclopentadiene. 37 and 47 are not so easily defined. Experimentally, slippage of Cp rings from q5 coordination is often observed and q3 or q4 coordination may or may not be invoked. Somewhat arbitrarily we define 317 at the intersection of the transit line with the line joining C-2 and C-5 projected on the transit plane. The tetrahapto coordination site is most ambiguous (it could be near 37 or near 57), and SO we will not label any position as such. The analysis will consist of an inspection of interaction diagrams for the orbitals of Cp and X, as the ligand X and its position along the transit are varied. The qualitative arguments based on symmetry and overlap are supported by extended Huckel calculations whose details are given in the Appendix. The reader should be aware that this is an approximate metho

    Fish-Hook

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    Patent for a fish hook with additional hooks attached in order to ensure a caught fish remains on the hook

    Primary Care Medical Training, Chronic Illness, and Psychological Trauma: Education, Assessment, and Intervention

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    This presentation was given at the Mercer University Health Sciences Research Conference
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