657 research outputs found

    Generation of Spin-Adapted and Spin-Complete Substitution Operators for (High-Spin) Open-Shell Coupled Cluster of Arbitrary Order

    Full text link
    A rigorous generation of spin-adapted (spin-free) substitution operators for high spin (S=SzS=S_z) references of arbitrary substitution order and spin quantum number SS is presented. The generated operators lead to linearly independent but non-orthogonal CSFs when applied to the reference and span the complete spin space. To incorporate spin completeness, spectating substitutions (as e.g. E^ivva\hat{E}_{iv}^{va}) are introduced. The presented procedure utilizes L\"owdin's projection operator method of spin eigenfunction generation to ensure spin completeness. The generated operators are explicitly checked for (i) their linear independence and (ii) their spin completeness for up to 10-fold substitutions and up to a multiplicity of 2S+1=112S+1 = 11. A proof of concept implementation utilizing the generated operators in a coupled cluster (CC) calculation was successfully applied to the high spin states of the Boron atom. The results show pure spin states as well as small effects on the correlation energy compared to spinorbital CC. A comparison to spin-adapted but spin-incomplete CC shows a significant spin incompleteness error.Comment: 18 pages, 5 figures, 5 table

    Palynomorph preservation in volcaniclastic rocks of the Miocene Tepoztlan formation (Central Mexico) and implications for paleoenvironmental reconstruction

    Get PDF
    Palynomorph preservation in sedimentary rocks is strongly affected by various taphonomic factors related to transport, deposition, diagenesis and preservation potential. The palynological record may contribute to distinguish different taphonomic factors and also displays changes in paleoenvironment, especially in volcanic settings where a very complex interaction of eruptive, gravitational and fluvial processes in time and space can be observed. Herein, we report on new palynological data from the Miocene Tepoztlán Formation. The 800 m thick formation mainly consists of pyroclastic rocks, mass flow units (lahars) and fluvial deposits. It is part of the southern Transmexican Volcanic Belt, cropping out south of the Valley of Mexico and within the two states of Morelos and Mexico State. The volcaniclastic succession records various stages of recovery of vegetation related to a wide variety of disturbance factors and mechanisms. During the entire period of deposition, mixed mesophytic forests appear to have been widespread in the lowlands along streams and midaltitude uplands surrounding the valley. Pollen assemblages were repeatedly reset by volcanic eruptions or their secondary effects (lahars) to more limited assemblages with gradual recoveries to the initial stages before the eruption. A clear distinction can be made between samples taken from different transport regimes (fluvial, lahar and pyroclastic flow transport). The highest percentages of well-preserved, amorphous, and crumpled palynomorphs can be found in fluvial sediments while the highest percentage of fragmented palynomorphs is characteristic of lahar deposits. In contrast, the highest percentage of corroded palynomorphs can be found in deposits originating from pyroclastic flows.http://palaios.sepmonline.orghb201

    Outcomes and risk factors for cancer patients undergoing endoscopic intervention of malignant biliary obstruction

    Get PDF
    Background: Malignant bile duct obstruction is a common problem among cancer patients with hepatic or lymphatic metastases. Endoscopic retrograde cholangiography (ERC) with the placement of a stent is the method of choice to improve biliary flow. Only little data exist concerning the outcome of patients with malignant biliary obstruction in relationship to microbial isolates from bile. Methods: Bile samples were taken during the ERC procedure in tumor patients with biliary obstruction. Clinical data including laboratory values, tumor-specific treatment and outcome data were prospectively collected. Results: 206 ERC interventions in 163 patients were recorded. In 43 % of the patients, systemic treatment was (re-) initiated after successful biliary drainage. A variety of bacteria and fungi was detected in the bile samples. One-year survival was significantly worse in patients from whom multiresistant pathogens were isolated than in patients, in whom other species were detected. Increased levels of inflammatory markers were associated with a poor one-year survival. The negative impact of these two factors was confirmed in multivariate analysis. In patients with pancreatic cancer, univariate analysis showed a negative impact on one-year survival in case of detection of Candida species in the bile. Multivariate analysis confirmed the negative prognostic impact of Candida in the bile in pancreatic cancer patients. Conclusion: Outcome in tumor patients with malignant bile obstruction is associated with the type of microbial biliary colonization. The proof of multiresistant pathogens or Candida, as well as the level of inflammation markers, have an impact on the prognosis of the underlying tumor disease

    Quantum utility -- definition and assessment of a practical quantum advantage

    Full text link
    Several benchmarks have been proposed to holistically measure quantum computing performance. While some have focused on the end user's perspective (e.g., in application-oriented benchmarks), the real industrial value taking into account the physical footprint of the quantum processor are not discussed. Different use-cases come with different requirements for size, weight, power consumption, or data privacy while demanding to surpass certain thresholds of fidelity, speed, problem size, or precision. This paper aims to incorporate these characteristics into a concept coined quantum utility, which demonstrates the effectiveness and practicality of quantum computers for various applications where quantum advantage -- defined as either being faster, more accurate, or demanding less energy -- is achieved over a classical machine of similar size, weight, and cost. To successively pursue quantum utility, a level-based classification scheme -- constituted as application readiness levels (ARLs) -- as well as extended classification labels are introduced. These are demonstratively applied to different quantum applications from the fields of quantum chemistry, quantum simulation, quantum machine learning, and data analysis followed by a brief discussion

    First quantum machine learning applications on an on-site room-temperature quantum computer

    Full text link
    We demonstrate - for the first time - the application of a quantum machine learning (QML) algorithm on an on-site room-temperature quantum computer. A two-qubit quantum computer installed at the Pawsey Supercomputing Centre in Perth, Australia, is used to solve multi-class classification problems on unseen, i.e. untrained, 2D data points. The underlying 1-qubit model is based on the data re-uploading framework of the universal quantum classifier and was trained on an ideal quantum simulator using the Adam optimiser. No noise models or device-specific insights were used in the training process. The optimised model was deployed to the quantum device by means of a single XYX decomposition leading to three parameterised single qubit rotations. The results for different classification problems are compared to the optimal results of an ideal simulator. The room-temperature quantum computer achieves very high classification accuracies, on par with ideal state vector simulations.Comment: 7 pages, 5 figure

    Removal of cells from body fluids by magnetic separation in batch and continuous mode: influence of bead size, concentration, and contact time

    Get PDF
    The magnetic separation of pathogenic compounds from body fluids is an appealing therapeutic concept. Recently, removal of a diverse array of pathogens has been demonstrated using extracorporeal dialysis-type devices. The contact time between the fluid and the magnetic beads in such devices is limited to a few minutes. This poses challenges, particularly if large compounds such as bacteria or cells need to be removed. Here, we report on the feasibility to remove cells from body fluids in a continuous dialysis type of setting. We assessed tumor cell removal efficiencies from physiological fluids with or without white blood cells using a range of different magnetic bead sizes (50–4000 nm), concentrations, and contact times. We show that tumor cells can be quantitatively removed from body fluids within acceptable times (1– 2 min) and bead concentrations (0.2 mg per mL). We further present a mathematical model to describe the minimal bead number concentration needed to remove a certain number of cells, in the presence of competing nonspecific uptake. The present study paves the way for investigational studies to assess the therapeutic potential of cell removal by magnetic blood purification in a dialysis-like setting

    Carbon Nanotube Network Ambipolar Field-Effect Transistors with 10(8) On/Off Ratio

    Get PDF
    Polymer wrapping is a highly effective method of selecting semiconducting carbon nanotubes and dispersing them in solution. Semi-aligned semiconducting carbon nanotube networks are obtained by blade coating, an effective and scalable process. The field-effect transistor (FET) performance can be tuned by the choice of wrapping polymer, and the polymer concentration modifies the FET transport characteristics, leading to a record on/off ratio of 108

    The Samurai Project: verifying the consistency of black-hole-binary waveforms for gravitational-wave detection

    Get PDF
    We quantify the consistency of numerical-relativity black-hole-binary waveforms for use in gravitational-wave (GW) searches with current and planned ground-based detectors. We compare previously published results for the (=2,m=2)(\ell=2,| m | =2) mode of the gravitational waves from an equal-mass nonspinning binary, calculated by five numerical codes. We focus on the 1000M (about six orbits, or 12 GW cycles) before the peak of the GW amplitude and the subsequent ringdown. We find that the phase and amplitude agree within each code's uncertainty estimates. The mismatch between the (=2,m=2)(\ell=2,| m| =2) modes is better than 10310^{-3} for binary masses above 60M60 M_{\odot} with respect to the Enhanced LIGO detector noise curve, and for masses above 180M180 M_{\odot} with respect to Advanced LIGO, Virgo and Advanced Virgo. Between the waveforms with the best agreement, the mismatch is below 2×1042 \times 10^{-4}. We find that the waveforms would be indistinguishable in all ground-based detectors (and for the masses we consider) if detected with a signal-to-noise ratio of less than 14\approx14, or less than 25\approx25 in the best cases.Comment: 17 pages, 9 figures. Version accepted by PR

    Transcription at the proximity of the nuclear pore: A role for the THP1-SAC3-SUS1-CDC31 (THSC) complex

    Get PDF
    4 páginas, 1 figura.A key aspect of eukaryotic gene expression is the coupling of transcription with RNA processing, polyadenylation and export. The use of new techniques based on tandem affinity purification (TAP) and chromatin immunoprecipitation (ChIP), and of genetic and cell biology approaches has contributed to the beginning of deciphering the network of protein-mRNA interactions accompanying this coupling. Although an extensive amount of work has shed light on this matter, the order of participation and precise role of the different proteins remain to be deciphered. It seems that different and sequential protein interactions must converge to finally promote the anchoring of genes to the nuclear periphery. Here we discuss the new data on the coupling of gene expression and RNA export, with emphasis on the THP1-SAC3-SUS1-CDC31 complex and the possible implications of these results on transcription at the nuclear pore.Research in A.A.’s lab is funded by grants from the Spanish Ministry of Science and Education and the Junta de Andalucía.Peer reviewe

    Optimized utilization of Salix-Perspectives for the genetic improvement toward sustainable biofuel value chains

    Get PDF
    Bioenergy will be one of the most important renewable energy sources in the conversion from fossil fuels to bio-based products. Short rotation coppice Salix could be a key player in this conversion since Salix has rapid growth, positive energy balance, easy to manage cultivation system with vegetative propagation of plant material and multiple harvests from the same plantation. The aim of the present paper is to provide an overview of the main challenges and key issues in willow genetic improvement toward sustainable biofuel value chains. Primarily based on results from the research project "Optimized Utilization of Salix" (OPTUS), the influence of Salix wood quality on the potential for biofuel use is discussed, followed by issues related to the conversion of Salix biomass into liquid and gaseous transportation fuels. Thereafter, the studies address genotypic influence on soil carbon sequestration in Salix plantations, as well as on soil carbon dynamics and climate change impacts. Finally, the opportunities for plant breeding are discussed using willow as a resource for sustainable biofuel production. Substantial phenotypic and genotypic variation was reported for different wood quality traits important in biological (i.e., enzymatic and anaerobic) and thermochemical conversion processes, which is a prerequisite for plant breeding. Furthermore, different Salix genotypes can affect soil carbon sequestration variably, and life cycle assessment illustrates that these differences can result in different climate mitigation potential depending on genotype. Thus, the potential of Salix plantations for sustainable biomass production and its conversion into biofuels is shown. Large genetic variation in various wood and biomass traits, important for different conversion processes and carbon sequestration, provides opportunities to enhance the sustainability of the production system via plant breeding. This includes new breeding targets in addition to traditional targets for high yield to improve biomass quality and carbon sequestration potential
    corecore