U/Th dating of Quaternary travertines at the middle River Llobregat (NE Iberian Peninsula, Nortwestern Mediterranean). Correlation with sea-level changes

The dating of the fluvial terraces of the middle River Llobregat enabled one to establish a correlation between the sedimentation episodes in continental zones and in neighbouring deltaic and coastal areas in the NE Iberian continental margin. The fluvial Terraces 4 (+85-95 m above river level) and 3 (+55-65 m above river level) are made up by or include travertines, which were deposited around 350,000 and 111,000 years ago, respectively. These radiometric ages correspond to two high sea level periods: the Eemian interglacial (isotopic stage 5e) and the interglacial related to isotopic stage 9. However, other travertine units in the valley, such as the Can Tobella staggered cascade travertines, were formed during the Holocene, probably due to hydrothermal spring activity related to the tectonic contact between the Catalan Coastal Ranges and the Ebro Basin

Phase shift rule with the optimal parameter selection

The phase shift rules enable the estimation of the derivative of a quantum state with respect to phase parameters, providing valuable insights into the behavior and dynamics of quantum systems. This capability is essential in quantum simulation tasks where understanding the behavior of complex quantum systems is of interest, such as simulating chemical reactions or condensed matter systems. However, parameter shift rules are typically designed for Hamiltonian systems with equidistant eigenvalues. For systems with closely spaced eigenvalues, effective rules have not been established. We provide insights about the optimal design of a parameter shift rule, tailored to various sorts of spectral information that may be available. The proposed method lets derivatives be calculated for any system, regardless of how close the eigenvalues are to each other. It also optimizes the number of phase shifts, which reduces the amount of gate resources needed.Comment: 24 pages, 2 figure

Climatic and land use changes on the NW of Iberian Peninsula recorded in a 1500-year record from Lake Sanabria

L'estudi de diversos descriptors paleoambientals com ara el pol·len, les diatomees i la sedimentologia, realitzat en sediments procedents del llac de Sanabria (NO de la península Ibèrica), ha aportat informació sobre les oscil·lacions climàtiques atribuïdes als períodes càlids tardoromà i medieval, així com a la petita edat del gel. Entre els anys 440 i 950 dC, el clima es caracteritzà per temperatures suaus i un règim de precipitacions mediterrani, malgrat l'existència de pulsacions més fredes vers els anys 530 i 700 dC. Les evidències pol·líniques dels usos del sòl indiquen l'extensió d'activitats ramaderes i agrícoles. Aquesta fase correspon al final del període càlid romà i al període càlid medieval. El canvi de condicions climàtiques es produeix entre els anys 950 i 1100 dC, moment en què els valors mínims de matèria orgànica, pol·len arbori, concentració de diatomees, nitrogen total (TN) i mida del gra indiquen temperatures més baixes i un règim de precipitacions més regular. Aquest període correspon a la petita edat del gel, que finalitzà vers l'any 1590 dC. Posteriorment, la productivitat del llac tendeix a recuperar els valors previs, malgrat que es produeixen episodis freds i curts. Els valors de carbó orgànic total, TN i diatomees covarien amb els índexs de temperatura del NO de la península Ibèrica i posarien de manifest que, amb anterioritat a l'era industrial, el sistema lacustre de Sanabria estava controlat principalment per les condicions climàtiques. Des de l'any 1920 dC, la productivitat del llac està influenciada per l'activitat humana.This multi-proxy paleoenvironmental study from Lake Sanabria (NW Iberian Peninsula), based on pollen, diatom, and sedimentology, provides evidences of climatic oscillations attributed to the Late Roman and Medieval Warm Periods as well as the Little Ice Age (LIA). From 440 to 950 AD, the climate was characterized by mild temperatures and a Mediterranean rainfall regime, although climatic cold periods were recorded at ca. 530 and 700. Evidence from pollen indicators of land-use suggests that grazing and farming were widespread activities. This period corresponds to the end of the Roman Warm Period and the Medieval Warm Period. The onset of new climate conditions occurred between 950 and 1100 AD, as minimum values of organic matter, arboreal pollen, diatom concentration, total nitrogen (TN), and grain size indicate low temperatures and a more regular rainfall regime. This period corresponds to the LIA and ended at 1590 AD, when lake productivity tended to recover to previous values in spite of the occurrence of cool events. Total organic carbon, TN, and diatom content covary with the temperature index for the NW Iberia, suggesting that Lake Sanabria was mainly controlled by climate before the industrial period. Since 1920 AD, lake productivity has been mainly influenced by human activity

Bell correlation depth in many-body systems

We address the question of assessing the number of particles sharing genuinely nonlocal correlations in a multipartite system. While the interest in multipartite nonlocality has grown in recent years, its existence in large quantum systems is difficult to confirm experimentally. This is mostly due to the inadequacy of standard multipartite Bell inequalities to many-body systems: Such inequalities usually rely on expectation values involving many parties, usually all, and require individual addressing of each party. In addition, known Bell inequalities for genuine nonlocality are composed of a number of expectation values that scales exponentially with the number of observers, which makes such inequalities impractical from the experimental point of view. In a recent work [Tura et al., Science 344, 1256 (2014)], it was shown that it is possible to detect nonlocality in multipartite systems using Bell inequalities with only two-body correlators. This opened the way for the detection of Bell correlations with trusted collective measurements through Bell correlation witnesses [Schmied et al., Science 352, 441 (2016)]. These witnesses were recently tested experimentally in many-body systems such as Bose-Einstein condensate or thermal ensembles, hence demonstrating the presence of Bell correlations with assumptions on the statistics. Here, we address the problem of detecting nonlocality depth, a notion that quantifies the number of particles sharing nonlocal correlation in a multipartite system. We introduce a general framework allowing us to derive Bell-like inequalities for nonlocality depth from symmetric two-body correlators. We characterize all such Bell-like inequalities for a finite number of parties and we show that they reveal Bell correlation depth k <= 6 in arbitrarily large systems. We then show how Bell correlation depth can be estimated using quantities that are within reach in current experiments. On one hand, we use the standard multipartite Bell inequalities such the Mermin and Svetlichny ones to derive Bell correlations witnesses of any depth that involves only two collective measurements, one of which being the parity measurement. On the other hand, we show that our two-body Bell inequalities can be turned into witnesses of depth k <= 6 that require measuring total spin components in certain directions. Interestingly, such a witness is violated by existing data from an ensemble of 480 atoms

The effect of sulfur on chemical looping combustion with iron oxides

Advancing climate change poses an increasing threat to humanity, together with the higher demand for energy around the world. New ‘cleaner’ technologies for the production of energy from solid fuels (coal or biomass) via thermo-chemically viable routes are required. Chemical looping combustion (CLC) is a process concept using metal oxide (oxygen carrier) for transportation of oxygen from air for electrical power generation and inherent production of a pure stream of CO2. CLC has been generally applied to gaseous fuel; however, by integrating chemical looping and gasification, the combined process shows great potential for producing H2 and power from solid fuels. Coal and biomass contain significant quantities of sulfur. Upon gasification, the sulfur is released in the form of H2S, which will be then be introduced into the iron-based chemical looping process, followed by further gasification. Iron oxides are known to form stable sulfides under reducing conditions. The performance of chemical looping using iron-based oxygen carrier could therefore be adversely affected by the introduction of H2S in a real system. The overarching aim of this thesis is to assess the effect of H2S on chemical looping combustion using iron (III) oxide in a laboratory scale spouted bed reactor. A closed-system spouted bed reactor has been designed and constructed to study the solid looping system with gaseous fuel. A model of the bed was developed, from which the bed could reasonably be assumed to be a well-mixed bubbling fluidised bed reactor at certain conditions. The reactor was used for the kinetic study of reduction of Fe2O3 to Fe3O4 with a CO/CO2 mixture under isothermal condition at the temperature range of 723K – 973K. The oxygen carrier before and after thermal cycling was characterised using SEM, mercury porosimetry, BET surface area analysis. Using a nominal particle size of Fe2O3, the rate of reduction was controlled mainly by intrinsic chemical reaction kinetics with a high effectiveness factor. The intrinsic rate constant was estimated with an activation energy of 73 kJ mol-1, which is comparable to values reported in the literature. The reactor was modified for use in the quartz internal, together with acid-washed, calcined sand (Quartz-T) to be able to significantly reduce interactions between sulfur and the inert material used in the construction of the reactor and the spouted bed. The fate of H2S in the chemical looping cycling was determined and the effect of H2S on reduction of Fe2O3 to Fe3O4 over multiple cycles was studied. There were two major mechanisms of reaction between H2S and Fe2O3 that were found to affect the rate of reduction of Fe2O3 and main sulfur product distribution: (1) production of SO2 as a main sulfur product, (2) production of FeS as a main sulfur product. The dominating mechanism was found to depend on the thermodynamic potential of S2, the thermodynamic potential of O2 (which depends on the extent of reduction), and the temperature. The effect of the H2S on the kinetics of reduction was found to be due to the structural change of Fe2O3 particles that is governed by the reaction between H2S and Fe2O3. A mathematical simulation based on a grain model under chemical reaction control was used to satisfactorily describe the relationship between rate of reduction and the extent of the reaction in the presence of sulfur.Open Acces

Quantitative phase microscopy enables precise and efficient determination of biomolecular condensate composition

Many compartments in eukaryotic cells are protein-rich biomolecular condensates demixed from the cyto- or nucleoplasm. Although much has been learned in recent years about the integral roles condensates play in many cellular processes as well as the biophysical properties of reconstituted condensates, an understanding of their most basic feature, their composition, remains elusive. Here we combined quantitative phase microscopy (QPM) and the physics of sessile droplets to develop a precise method to measure the shape and composition of individual model condensates. This technique does not rely on fluorescent dyes or tags, which we show can significantly alter protein phase behavior, and requires 1000-fold less material than traditional label-free technologies. We further show that this QPM method measures the protein concentration in condensates to a 3-fold higher precision than the next best label-free approach, and that commonly employed strategies based on fluorescence intensity dramatically underestimate these concentrations by as much as 50-fold. Interestingly, we find that condensed-phase protein concentrations can span a broad range, with PGL3, TAF15(RBD) and FUS condensates falling between 80 and 500 mg/ml under typical in vitro conditions. This points to a natural diversity in condensate composition specified by protein sequence. We were also able to measure temperature-dependent phase equilibria with QPM, an essential step towards relating phase behavior to the underlying physics and chemistry. Finally, time-resolved QPM reveals that PGL3 condensates undergo a contraction-like process during aging which leads to doubling of the internal protein concentration coupled to condensate shrinkage. We anticipate that this new approach will enable understanding the physical properties of biomolecular condensates and their function

Holonomy from wrapped branes

Compactifications of M-theory on manifolds with reduced holonomy arise as the local eleven-dimensional description of D6-branes wrapped on supersymmetric cycles in manifolds of lower dimension with a different holonomy group. Whenever the isometry group SU(2) is present, eight-dimensional gauged supergravity is a natural arena for such investigations. In this paper we use this approach and review the eleven dimensional description of D6-branes wrapped on coassociative 4-cycles, on deformed 3-cycles inside Calabi-Yau threefolds and on Kahler 4-cycles.Comment: 1+8 pages, Latex. Proceedings of the Leuven workshop, 2002. v2: Corrected typos in equations (4)-(8

Identification of FOXP1 Deletions in Three Unrelated Patients with Mental Retardation and Significant Speech and Language Deficits

Mental retardation affects 2-3% of the population and shows a high heritability. Neurodevelopmental disorders that include pronounced impairment in language and speech skills occur less frequently. For most cases, the molecular basis of mental retardation with or without speech and language disorder is unknown due to the heterogeneity of underlying genetic factors. We have used molecular karyotyping on 1523 patients with mental retardation to detect copy number variations (CNVs) including deletions or duplications. These studies revealed three heterozygous overlapping deletions solely affecting the forkhead box P1 (FOXP1) gene. All three patients had moderate mental retardation and significant language and speech deficits. Since our results are consistent with a de novo occurrence of these deletions, we considered them as causal although we detected a single large deletion including FOXP1 and additional genes in 4104 ancestrally matched controls. These findings are of interest with regard to the structural and functional relationship between FOXP1 and FOXP2. Mutations in FOXP2 have been previously related to monogenic cases of developmental verbal dyspraxia. Both FOXP1 and FOXP2 are expressed in songbird and human brain regions that are important for the developmental processes that culminate in speech and language. ©2010 Wiley-Liss, Inc