Kerr effect as a tool for the investigation of dynamic heterogeneities

We propose a dynamic Kerr effect experiment for the distinction between dynamic heterogeneous and homogeneous relaxation in glassy systems. The possibility of this distinction is due to the inherent nonlinearity of the Kerr effect signal. We model the slow reorientational molecular motion in supercooled liquids in terms of non-inertial rotational diffusion. The Kerr effect response, consisting of two terms, is calculated for heterogeneous and for homogeneous variants of the stochastic model. It turns out that the experiment is able to distinguish between the two scenarios. We furthermore show that exchange between relatively 'slow' and 'fast' environments does not affect the possibility of frequency-selective modifications. It is demonstrated how information about changes in the width of the relaxation time distribution can be obtained from experimental results.Comment: 23 pages incl. 6 figures accepted for publication in The Journal of Chemical Physic

Correlation potentials for molecular bond dissociation within the self-consistent random phase approximation

Self-consistent correlation potentials for H$_2$ and LiH for various inter-atomic separations are obtained within the random phase approximation (RPA) of density functional theory. The RPA correlation potential shows a peak at the bond midpoint, which is an exact feature of the true correlation potential, but lacks another exact feature: the step important to preserve integer charge on the atomic fragments in the dissociation limit. An analysis of the RPA energy functional in terms of fractional charge is given which confirms these observations. We find that the RPA misses the derivative discontinuity at odd integer particle numbers but explicitly eliminates the fractional spin error in the exact-exchange functional. The latter finding explains the accurate total energy in the dissociation limit.Comment: 9 pages, 10 figure

Women Authors in Medicine: A Gender Based Study on Authorship Opportunities and its Implications in Promotions in Medicine

Obtaining first authorship in research and published papers is widely held as grounds for promotions and advancements in the medical field. However, the opportunities to be involved in research and to have the primary authorship position are not equally divided amongst specialties, including primary care. Women physicians are becoming a greater percentage of the workforce in primary care, including Internal Medicine and the potential lack of opportunity for authorship may disproportionately affect their promotion. This poster presents the preliminary research on an investigation into the Indiana University School of Medicine’s Department of Medicine gender authorship profiles in the last five years. By utilizing the search engine scopus, a database of the papers written by physicians was created, and gender identifications of the first, second, and last author was made to find correlations between gender and authorship positions. These results will be used to make a case for reexamining the qualifications for promotions, and ensuring that genders have equal opportunity for job advancement and leadership in the medical field.https://jdc.jefferson.edu/sexandgenderhealth/1014/thumbnail.jp

Exchange-correlation orbital functionals in current-density-functional theory: Application to a quantum dot in magnetic fields

The description of interacting many-electron systems in external magnetic fields is considered in the framework of the optimized effective potential method extended to current-spin-density functional theory. As a case study, a two-dimensional quantum dot in external magnetic fields is investigated. Excellent agreement with quantum Monte Carlo results is obtained when self-interaction corrected correlation energies from the standard local spin-density approximation are added to exact-exchange results. Full self-consistency within the complete current-spin-density-functional framework is found to be of minor importance.Comment: 5 pages, 2 figures, submitted to PR

Probing the pairing symmetry in the over-doped Fe-based superconductor Ba_0.35Rb_0.65Fe_2As_2 as a function of hydrostatic pressure

We report muon spin rotation experiments on the magnetic penetration depth lambda and the temperature dependence of lambda^{-2} in the over-doped Fe-based high-temperature superconductor (Fe-HTS) Ba_{1-x}Rb_ xFe_2As_2 (x = 0.65) studied at ambient and under hydrostatic pressures up to p = 2.3 GPa. We find that in this system lambda^{-2}(T) is best described by d-wave scenario. This is in contrast to the case of the optimally doped x = 0.35 system which is known to be a nodeless s^{+-}-wave superconductor. This suggests that the doping induces the change of the pairing symmetry from s^{+-} to d-wave in Ba_{1-x}Rb_{x}Fe_{2}As_{2}. In addition, we find that the d-wave order parameter is robust against pressure, suggesting that d is the common and dominant pairing symmetry in over-doped Ba_{1-x}Rb_{x}Fe_{2}As_{2}. Application of pressure of p = 2.3 GPa causes a decrease of lambda(0) by less than 5 %, while at optimal doping x = 0.35 a significant decrease of lambda(0) was reported. The superconducting transition temperature T_c as well as the gap to T_c ratio 2Delta/k_BT_c show only a modest decrease with pressure. By combining the present data with those previously obtained for optimally doped system x = 0.35 and for the end member x = 1 we conclude that the SC gap symmetry as well as the pressure effects on the SC quantities strongly depend on the Rb doping level. These results are discussed in the light of the putative Lifshitz transition, i.e., a disappearance of the electron pockets in the Fermi surface of Ba_{1-x}Rb_{x}Fe_{2}As_{2} upon hole doping.Comment: Accepted for publication in Physical Review

Focused Fluid Flow along the Nootka Fault Zone and Continental slope, Explorer‐Juan de Fuca Plate Boundary

Key Points: - Fluid flow is focused along Nootka Fault traces resulting in shallow bright spots - Two seafloor mounds are the result of basaltic intrusions in the Nootka Fault zone - Gas hydrates occur at the Nootka Slope and are imaged seismically as bottom- simulating reflectors suggesting a regional heat-flow of ~80 mW/m2 along the slope Abstract Geophysical and geochemical data indicate there is abundant fluid expulsion in the Nootka fault zone (NFZ) between the Juan de Fuca and Explorer plates and the Nootka continental slope. Here we combine observations from > 20 years of investigations to demonstrate the nature of fluid‐flow along the NFZ, which is the seismically most active region off Vancouver Island. Seismicity reaching down to the upper mantle is linked to near‐seafloor manifestation of fluid flow through a network of faults. Along the two main fault traces, seismic reflection data imaged bright spots 100 – 300 m below seafloor that lie above changes in basement topography. The bright spots are conformable to sediment layering, show opposite‐to‐seafloor reflection polarity, and are associated with frequency‐reduction and velocity push‐down indicating the presence of gas in the sediments. Two seafloor mounds ~15 km seaward of the Nootka slope are underlain by deep, non‐conformable high amplitude reflective zones. Measurements in the water column above one mound revealed a plume of warm water, and bottom‐video observations imaged hydrothermal vent system biota. Pore fluids from a core at this mound contain predominately microbial methane (C1) with a high proportion of ethane (C2) yielding C1/C2 ratios < 500 indicating a possible slight contribution from a deep source. We infer the reflective zones beneath the two mounds are basaltic intrusions that create hydrothermal circulation within the overlying sediments. Across the Nootka continental slope, gas hydrate related bottom‐simulating reflectors are widespread and occur at depths indicating heat‐flow values of 80 – 90 mW/m2

Evidence for strong lattice effects as revealed from huge unconventional oxygen isotope effects on the pseudogap temperature in La2−x_{2-x}Srx_{x}CuO4_{4}

The oxygen isotope ($^{16}$O/$^{18}$O) effect (OIE) on the pseudogap (charge-stripe ordering) temperature $T^{\ast}$ is investigated for the cuprate superconductor La$_{2-x}$Sr$_{x}$CuO$_{4}$ as a function of doping $x$ by means of x-ray absorption near edge structure (XANES) studies. A strong $x$ dependent and sign reversed OIE on $T^{\ast}$ is observed. The OIE exponent $\alpha_{T^{\ast}}$ systematically decreases from $\alpha_{T^{\ast}} = - 0.6(1.3)$ for $x = 0.15$ to $\alpha_{T^{\ast}} = - 4.4(1.1)$ for $x = 0.06$, corresponding to increasing $T^{\ast}$ and decreasing superconducting transition temperature $T_{c}$. Both $T^{\ast}(^{16}{\rm O})$ and $T^{\ast}(^{18}{\rm O})$ exhibit a linear doping dependence with different slopes and critical end points (where $T^{\ast}(^{16}{\rm O})$ and $T^{\ast}(^{18}{\rm O})$ fall to zero) at $x_{c}(^{16}{\rm O}) = 0.201(4)$ and $x_{c}(^{18}{\rm O}) = 0.182(3)$, indicating a large positive OIE of $x_{c}$ with an exponent of $\alpha_{x_{c}} = 0.84(22)$. The remarkably large and strongly doping dependent OIE on $T^{\ast}$ signals a substantial involvement of the lattice in the formation of the pseudogap, consistent with a polaronic approach to cuprate superconductivity and the vibronic character of its ground state

Wer wird Pflegender, wer nicht? Eine motivationspsychologische Antwort. Die Rolle von Persönlichkeit und Beziehungsgestaltung im Übergang zur Pflege

Empirical literature thoroughly proves the burden and negative consequences on health that accompany caregiving. However, more recent findings point to existing between-person differences in care experiences highlighting the necessity for a closer look onto underlying processes and dynamics. With this in mind the current thesis offers a motivational perspective to the context of care adopting the Rubicon-deadline model of motivation (Heckhausen & Heckhausen, 2006). In doing so, the dissertation addresses three candidates that account for the heterogeneity in care experiences, namely caregivers’ personality, individual gain-loss-expectations, and the care relationship. Furthermore, the thesis concentrates on the transition into care which comes with regulative challenges and serves as crucial starting point of the caregiving career. Based on an action-theoretical understanding of individuals as active (co-)producers of their development three complementary empirical approaches were applied: After reviewing current research on caregiving the second study, a longitudinal approach, uses representative data of the German Socio-economic Panel (GSOEP, N = 14,495) to explore the role of personality in the transition to care. Results showed that more neurotic people tend to select into care contexts and emphasizes the heightened vulnerability of female care entrants. Study 3 is a web-based, quasi-experimental study (N = 485) focusing on gain-loss-expectations associated with the care context and the changing relationship within the transition to care. Results illustrate that anticipated care benefits and losses discriminate between potential caregivers and those who are undecided or unwilling to care. Likewise, these groups differ in their perception and their engagement for the relationship. More specifically, the closer people feel and the more they are prone to regulate unbalanced exchanges, the more likely they are willing to invest in the continuity of the relationship despite facing care-related challenges and take over care responsibility. Results prove the vital role of expected care gains and losses and relationship regulation efforts as antecedent of care decisions. Finally, in study 4 the role of relationship characteristics is considered in an in-terview study with 50 older adults with health impairments and their potential caregiving spouses (N = 100). Findings underline the importance of emotional closeness and perceived reciprocity as predictors for relationship outcomes. In addition, differential regulation patterns for potential caregivers and care receivers suggest that already in early periods of the transition adaptation processes accrue. Taken together, the results of the three empirical studies confirm the applicability of the motivational approach in order to outline the active role of individuals within this transition. Additionally, the thesis highlights the necessity to focus more deeply on the interplay of individual and contextual dynamics with a specific focus of the dyadic relationship processes to explain existing heterogeneity in care experiences and to offer new approaches for researchers and practitioners alike.Eine Vielzahl empirischer Befunde belegt die mit der Pflegeaufgabe einhergehende Belastung und die negativen Konsequenzen für das Wohlbefinden und die körperliche Gesundheit von Pflegenden. Gleichwohl berichten neuere Forschungsarbeiten von erlebten Positiva und Gewinnen in der Pflege und verweisen somit auf die Vielgestaltigkeit des Pflegeerlebens. Als mögliche Ursachen für die beobachtete Heterogenität werden insbesondere interindividuelle Unterschiede und Beziehungscharakteristika in den Blick genommen. Während deren Einfluss auf die Gestaltung und Bewertung der Pflegetätigkeit durch eine Reihe von Studien belegt ist, bleibt bis dato unklar, wie die beiden Aspekte im Übergang zur Pflege wirken. Hier wird häufig eine deskriptive Perspektive eingenommen, den Akteuren eine eher passive Rolle zugeschrieben und damit motivationale Prozesse nur wenig beleuchtet. Die vorliegende Arbeit versucht diese Lücke zu schließen, indem sie sich dem Übergang in die Pflege aus motivationspsychologischer Sicht nähert. Dazu wurde das Rubikon-Fristen-Modell der Motivation (Heckhausen & Heckhausen, 2006) auf den Kontext der Pflege übertragen und dessen Anwendbarkeit anhand dreier, sich ergänzender empirischer Studien untersucht: Nachdem zunächst in einer ersten Studie ein Überblick über die empirische Befundlage gegeben wird, widmet sich die zweite Studie der Frage, ob sich Individuen aufgrund ihrer Persönlichkeit in Pflegekontexte selektieren und wie der Übergang in die Pflege seinerseits die Persönlichkeitsentwicklung beeinflusst. Dazu greift die Studie auf repräsentative Längsschnittdaten des Sozio-ökonomischen Panels (SOEP, N = 14 495) zurück. Die Ergebnisse verweisen auf die bedeutende Rolle von Neurotizismus bei der Wahl und Gestaltung des Pflegekontexts. Außerdem wird deutlich, dass insbesondere weibliche Pflegeneulinge durch die Übernahme der Pflegeverantwortung belastet sind. Auf Grundlage dieser Befunde untersucht eine dritte, webbasierte Studie (N = 485) unter Verwendung eines quasiexperi-mentellen Zugangs, ob individuelle Gewinn-Verlust-Erwartungen als Antezedenten der Pflegebereitschaft fungieren. Zuerst werden pflege-, danach beziehungsspezifische Gewinne und Verluste in den Blick genommen. Es zeigt sich, dass die Gewinn-Verlust-Dynamiken zwischen Potentiell Pflegenden, Unentschiedenen und Pflegeunwilligen differenzieren und entsprechend gruppenspezifische beziehungsregulative Bemühungen nach sich ziehen. Im Vergleich zu Pflegeun-willigen etwa fühlen sich Pflegewillige der potentiell zu pflegenden Person näher und schätzen die Beziehung als ausgewogener ein. Gleichzeitig sind sie bereit, trotz pflegebedingter Herausforderungen stärker in die Aufrechterhaltung einer wechselseitigen Beziehung zu investieren. Schließlich erweitert die vierte Studie den Blick, in dem sie den Beziehungskontext als eine der wichtigsten Rahmenbedingungen in den Fokus der Betrachtung rückt. In einer Interviewstudie mit 50 älteren, gesundheitlich beeinträchtigten Personen und ihren potentiell pflegenden (Ehe-)Partnern (N = 100) werden dyadische Aushandlungsprozesse in der Wahrnehmung des Miteinanders und der Beziehungsgestaltung untersucht. Die Ergebnisse belegen dabei die Rolle subjektiver Nähe und wahrgenommener Reziprozität als grundlegende Charakteristika im Übergang zur Pflege. Zudem verweisen sie darauf, dass bereits in frühen Phasen der Pflegekarriere erste Anpassungsprozesse stattfinden, welche die unterschiedlichen Anforderungen und Chancen der beiden Akteure widerspiegeln. Die Ergebnisse der drei empirischen Studien unterstreichen die Anwendbarkeit des Rubikon-Fristen-Modells auf den Kontext der Pflege. Die motivationspsychologische Perspektive öffnet dabei den Blick für die aktive Rolle des Individuums und bereichert dadurch die gegenwärtige Befundlage, welche häufig soziodemografische und strukturelle Aspekte stark betont. Ziel zukünftiger Forschung muss es sein, das Zusammenspiel individueller und kontextueller Dynamiken noch besser zu verstehen und darüber Rückschlüsse auf zugrundeliegende Mechanismen und Prozessen zu erhalten