Effects of spin and orbital correlations on the optical spectral weights of transition-metal oxides

Within the scope of this thesis different transition-metal oxides with open d shells are investigated by means of spectroscopic ellipsometry in the energy range from 0.75eV to 5.5eV for temperatures ranging from 15K to 490K. The focus is on spin and orbital degrees of freedom and their impact on the optical spectra. The multipeak structures observed in the optical conductivity show a pronounced dependence on both temperature and polarization. We analyze the spectra in terms of multiplets which form the upper Hubbard band. Our optical analysis of the multi-orbital Mott-Hubbard insulators YVO3, GdVO3, and CeVO3 yields a consistent description of the observed absorption bands in terms of 3d3 excited states which constitute the upper Hubbard band and thereby solves the discrepancies of the optical spectra of YVO3 reported in the literature. The temperature and polarization dependence of the optical spectra reflects the complex spin and orbital ordering phase diagram of RVO3 (R=Y, rare earth ion). A comparison of our data with theoretical predictions based on either rigid orbital order or strong orbital fluctuations leads us to the conclusion that orbital fluctuations cannot be strong in RVO3. The line shape and temperature dependence of a feature observed in the optical conductivity at around 2eV gives evidence for an excitonic Mott-Hubbard resonance, i.e. not a truly bound state below the gap but a resonance within the absorption band, and demonstrates the important role played by the kinetic energy for exciton formation in orbitally ordered Mott-Hubbard insulators. Due to the layered structure of the correlated insulator LaSrFeO4 the optical spectra strongly depend on polarization. This anisotropy in combination with their different spectral weights offers an efficient tool to disentangle Mott-Hubbard excitations, corresponding to an electron transfer between neighboring Fe(3+) sites, and charge-transfer excitations, corresponding to an electron transfer from the oxygen 2p band to the Fe 3d band. We arrive at a consistent peak assignment and find that the lowest dipole-allowed excitation, which contributes to the in-plane optical conductivity only, is of Mott-Hubbard type. This result is rather unexpected at first sight as the 3d5 electron configuration of Fe(3+) is particularly stable due to the intra-atomic Hund exchange. We argue that the Fe 3d - O 2p hybridization and particularly the large splitting of the eg level originating from the tetragonal structure justify our result. The temperature dependence of the Mott-Hubbard excitations is only weak. This finding is in accordance with the fact that variations of nearest-neighbor spin-spin and orbital-orbital correlations are not strong below room temperature in LaSrFeO4 with a Néel temperature of 366K. A further concern of this work lies on the correlated insulators LaCoO3 and EuCoO3 with Co(3+) 3d6 electron configuration, which have attracted a lot of interest because of the spin-state degree of freedom. The low-spin state, the intermediate-spin state, and the high-spin state, lie energetically close in these pseudocubic perovskites. It is well established that a thermal population of the high-spin state takes place from the low-spin ground state at T>25K in LaCoO3. This so-called spin-state transition is shifted to much higher temperatures in the sister compound EuCoO3. In addition, we present optical data of the single-layered perovskites La(2-x)SrxCoO4 (x=0, 0.33, 0.45, 0.5, 0.9) and La1.5Ca0.5CoO4, which contain both Co(3+) 3d6 and Co(2+) 3d7 ions. In agreement with claims of the literature for a doping-induced spin-state transition from a Co(3+) low-spin state being realized in La(2-x)Sr(x)CoO4 for doping concentrations x<0.8 to a state of mixed Co(3+) low-spin and high-spin ions in LaSrCoO4, our optical spectra of La1.1Sr0.9CoO4 differ considerably from the spectra of the compounds with smaller doping concentrations. We assign the observed absorption bands to charge-transfer excitations from the oxygen 2p bands to the upper Hubbard bands. Surprisingly, we observe only small changes in the optical spectra of LaCoO3 across the spin-state transition temperature, our spectra of LaCoO3 resemble the spectra of La1.1Sr0.9CoO4 already at low temperatures

Hubbard exciton revealed by time-domain optical spectroscopy

We use broadband ultra-fast pump-probe spectroscopy in the visible range to study the lowest excitations across the Mott-Hubbard gap in the orbitally ordered insulator YVO3. Separating thermal and non-thermal contributions to the optical transients, we show that the total spectral weight of the two lowest peaks is conserved, demonstrating that both excitations correspond to the same multiplet. The pump-induced transfer of spectral weight between the two peaks reveals that the low-energy one is a Hubbard exciton, i.e. a resonance or bound state between a doublon and a holon. Finally, we speculate that the pump-driven spin-disorder can be used to quantify the kinetic energy gain of the excitons in the ferromagnetic phase.Comment: 5 pages and 6 figures, 9 pages and 12 figures with additional material

Instituto de Biotecnología y Desarrollo Azul de la Universidad de Málaga: una apuesta por una Acuicultura Azul

Noventa investigadores de la Universidad de Málaga pertenecientes a 21 grupos de investigación, se han organizado en un Instituto de Biotecnología y Desarrollo Azul, IBYDA. El objetivo del IBYDA es la investigación, la docencia, el desarrollo y la transferencia de conocimiento en el marco del desarrollo circular o azul; incluyendo el análisis económico de los proyectos, el modelado de diferentes escenarios, y su aplicación a la gestión y planificación del territorio. Así mismo, el instituto ofrecerá infraestructuras acuícolas y servicios, y promoverá el emprendimiento. La actividad transversal central del IBYDA es la Acuicultura Multitrófica como implementación de la estrategia de Biorrefinería, es decir, el aprovechamiento de distintos tipos de residuos para el cultivo de organismos, cuya biomasa se empleará para la obtención de productos de alto valor añadido.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Active behaviour during early development shapes glucocorticoid reactivity

TGlucocorticoids are the final effectors of the stress axis, with numerous targets in the central nervous system and the periphery. They are essential for adaptation, yet currently it is unclear how early life events program the glucocorticoid response to stress. Here we provide evidence that involuntary swimming at early developmental stages can reconfigure the cortisol response to homotypic and heterotypic stress in larval zebrafish (Danio rerio), also reducing startle reactivity and increasing spontaneous activity as well as energy efficiency during active behaviour. Collectively, these data identify a role of the genetically malleable zebrafish for linking early life stress with glucocorticoid function in later life

Winter surface salinity in the northeastern Gulf of Maine from five years of SMAP satellite data

Wintertime freshwater transport into the Gulf of Maine (GoM) is typically controlled by a seasonal velocity increase in the fresh upstream Nova Scotia Current (NSC). Repeat satellite observations from the Soil Moisture Active Passive mission have mapped significant GoM surface salinity anomalies in four of five recent winters. These satellite data are used in combination with Jordan basin buoy and model datasets to investigate the likelihood that variable wind-forcing of the NSC contributed to these anomalies. This stems from regional ocean circulation studies suggesting that strengthening of alongshore southwesterly winds on the Scotian shelf weakens NSC transport into the GoM, while cross-shore southeasterly winds may also contribute to NSC weakening, and vice versa. A 17-year time series analysis of GoM buoy and satellite data shows that near-surface salinity in the eastern GoM can indeed be modulated by both alongshore and cross-shore winds through their impact on the NSC. The NSC geostrophic current modulation correlates with buoy-observed surface salinity anomalies when using a one month advective lead time. For a shorter 5-year period, a SMAP-derived salinity anomaly index in the eastern GoM indicates a similar relation to NSC variation and also correlates with Scotian Shelf wind anomalies. The relationships between winter wind and NSC transport variability are confirmed using output from a 19-year high resolution global ocean simulation. Attribution of these local wind anomalies to basin-scale atmospheric patterns shows that most years with strong winter GoM freshening coincide with weakening of a North Atlantic Oscillation-like wind pattern. But its reversals do not always correspond with a saline GoM. This contrast suggests that wind forcing more directly controls fresh winter GoM anomalies but not salty. Instead, they are partly due to density-driven advection from neighboring warm and saline Atlantic slope water including episodic Gulf Stream instabilities

Das Europäische Parlament

In einem jahrzehntelangen Prozess hat sich das Europäische Parlament von einer beratenden Einrichtung zu einem Mitgestalter europäischer Politik entwickelt. Heute besitzt es sowohl innerhalb der Union als auch als globaler Akteur politisches Gewicht. Diese Erfolgsgeschichte wird von den europäischen Bürgerinnen und Bürgern nur beschränkt wahrgenommen, wie die geringe Beteiligung an den Wahlen zum Europäischen Parlament zeigt. Das vorliegende Buch beantwortet zentrale Fragen: Wie funktioniert diese demokratisch legitimierte Institution? Was bedeutet ihr Machtzuwachs konkret? Welche weiteren Entwicklungen können erwartet werden?In May 2014 the 8th European elections take place. 751 Members of Parliament form 28 different countries are directly elected for a five-year term form an electorate of 383 Mio citizens. The European Parliament is a dynamic, truly supranational and since Lisbon a more and more powerful actor. It negotiates on eye-level with the Council of Ministers, holds the European Commission effectively accountable, represents the aggregated interests, ideas and concerns of the Union's citizens, and supervises the development of the EU together with the national parliaments. As a global player the European Parliament deals with members of parliaments of third countries, negotiates international agreements and watches over the protection of human rights and democracy. The authors - MEPs, officials, stakeholders and experts - gibe a deep practical and academic insight into all functions of the European Parliament. The different articles take into account the specific conditions of the EU's only directly legitimized institution. For academics and practitioners alike, Dialer, Neisser and Lichtenberger offer a superb "guide" for any serious understanding of the world's only elected transnational parliament

Personalized drug testing in human pheochromocytoma/paraganglioma primary cultures

Aggressive pheochromocytomas and paragangliomas (PPGLs) are difficult to treat, and molecular targeting is being increasingly considered, but with variable results. This study investigates established and novel molecular-targeted drugs and chemotherapeutic agents for the treatment of PPGLs in human primary cultures and murine cell line spheroids. In PPGLs from 33 patients, including 7 metastatic PPGLs, we identified germline or somatic driver-mutations in 79% of cases, allowing us to assess potential differences in drug responsivity between pseudohypoxia-associated cluster 1- (n=10) and kinase signaling-associated cluster 2-related (n=14) PPGL primary cultures. Single anti-cancer drugs were either more effective in cluster 1 (cabozantinib, selpercatinib, 5-FU) or similarly effective in both clusters (everolimus, sunitinib, alpelisib, trametinib, niraparib, entinostat, gemcitabine, AR-A014418, high-dose zoledronic acid). High-dose estrogen and low-dose zoledronic acid were the only single substances more effective in cluster 2. Neither cluster 1- nor cluster 2-related patient primary cultures responded to HIF-2α inhibitors, temozolomide, dabrafenib, or octreotide. We showed particular efficacy of targeted combination treatments (cabozantinib/everolimus, alpelisib/everolimus, alpelisib/trametinib) in both clusters, with higher efficacy of some targeted combinations in cluster 2 and overall synergistic effects (cabozantinib/everolimus, alpelisib/trametinib) or synergistic effects in cluster 2 (alpelisib/everolimus). Cabozantinib/everolimus combination therapy, gemcitabine, and high-dose zoledronic acid appear to be promising treatment options with particularly high efficacy in SDHB-mutant and metastatic tumors. In conclusion, only minor differences regarding drug responsivity were found between cluster 1 and cluster 2: some single anti-cancer drugs were more effective in cluster 1 and some targeted combination treatments were more effective in cluster 2

Personalized drug testing in human pheochromocytoma/paraganglioma primary cultures

: Aggressive pheochromocytomas and paragangliomas (PPGLs) are difficult to treat, and molecular targeting is being increasingly considered, but with variable results. This study investigates established and novel molecular-targeted drugs and chemotherapeutic agents for the treatment of PPGLs in human primary cultures and murine cell line spheroids. In PPGLs from 33 patients, including 7 metastatic PPGLs, we identified germline or somatic driver-mutations in 79% of cases, allowing us to assess potential differences in drug responsivity between pseudohypoxia-associated cluster 1- (n=10) and kinase signaling-associated cluster 2-related (n=14) PPGL primary cultures. Single anti-cancer drugs were either more effective in cluster 1 (cabozantinib, selpercatinib, 5-FU) or similarly effective in both clusters (everolimus, sunitinib, alpelisib, trametinib, niraparib, entinostat, gemcitabine, AR-A014418, high-dose zoledronic acid). High-dose estrogen and low-dose zoledronic acid were the only single substances more effective in cluster 2. Neither cluster 1- nor cluster 2-related patient primary cultures responded to HIF-2α inhibitors, temozolomide, dabrafenib, or octreotide. We showed particular efficacy of targeted combination treatments (cabozantinib/everolimus, alpelisib/everolimus, alpelisib/trametinib) in both clusters, with higher efficacy of some targeted combinations in cluster 2 and overall synergistic effects (cabozantinib/everolimus, alpelisib/trametinib) or synergistic effects in cluster 2 (alpelisib/everolimus). Cabozantinib/everolimus combination therapy, gemcitabine, and high-dose zoledronic acid appear to be promising treatment options with particularly high efficacy in SDHB-mutant and metastatic tumors. In conclusion, only minor differences regarding drug responsivity were found between cluster 1 and cluster 2: some single anti-cancer drugs were more effective in cluster 1 and some targeted combination treatments were more effective in cluster 2