Transition to the Haldane phase driven by electron-electron correlations

One of the most famous quantum systems with topological properties, the spin [Formula: see text] antiferromagnetic Heisenberg chain, is well-known to display exotic [Formula: see text] edge states. However, this spin model has not been analyzed from the more general perspective of strongly correlated systems varying the electron-electron interaction strength. Here, we report the investigation of the emergence of the Haldane edge in a system of interacting electrons - the two-orbital Hubbard model-with increasing repulsion strength U and Hund interaction JH. We show that interactions not only form the magnetic moments but also form a topologically nontrivial fermionic many-body ground-state with zero-energy edge states. Specifically, upon increasing the strength of the Hubbard repulsion and Hund exchange, we identify a sharp transition point separating topologically trivial and nontrivial ground-states. Surprisingly, such a behaviour appears already at rather small values of the interaction, in a regime where the magnetic moments are barely developed.

POS1156 INFECTIONS AND OTHER ADVERSE EFFECTS WITH BIOLOGICAL THERAPIES OVER THE PAST 10 YEARS

Background:

Biological therapies have marked a difference in the treatment of many autoimmune conditions. As all treatments, they have their side effects although little evidence of long-term effects has been reported.

Objectives:

Analyze retrospectively the appearance of infections that required hospitalization and other side effects in patients treated with biological therapies over the past 10 years.

Methods:

Biological drugs dispensed in our center to non-cancer patients from 2008 to 2018 were reviewed. Health records were collected from our database and all statistical analyzes were performed with the SPSS program.

Results:

24 different biological drugs applied to 34 medical conditions; 847 treatments were dispensed over a total of 555 patients. The median age was 44 years with a mean duration of 3.6 years of treatment. The most commonly used drug were adalimumab (n = 280, 33%), infliximab (n = 119, 12%), etanercept (n = 97.13%), rituximab (n = 63, 7%), vedolizumab (n = 47, 5.5%) and omalizumab (n = 43.5%). The rest of the drugs were administered <30 times each (ustekinumab, golimumab, certolizumab, tocilizumab, secukinumab and abatacept), representing <4% of the total sample.

The underlying conditions included Crohn’s Disease (n = 262, 31%), rheumatoid arthritis (n = 133, 16%), ulcerative colitis (n = 118, 14%), spondyloarthropathies (n = 86, 10%), psoriatic arthritis (n = 56, 7%), psoriasis (n = 49, 6%), asthma (n = 34, 4%), nephropathies (n = 19, 2%) and vasculitis (n = 13, 1.5%). The rest were pathologies with <10 cases.

During treatment, infection requiring hospitalization occurred in 10.2% (n = 86). The most frequent focus of infection was respiratory (n = 23, 27%), abdominal (n = 19, 22%), soft tissue-bone (n = 17 cases, 20%), urinary (n = 7, 8%) and tuberculosis (n = 4, 5%). No case of hepatitis reactivation was observed. At the time of hospital admission, 46% of patients were only under biological therapy, 21% had another non-corticosteroid immunosuppressant, 17% were associated with corticosteroid, and 15% had triple therapy (corticosteroids, another immunosuppressant and the biological drug). The drugs associated with more infections were: abatacept 20%, rituximab 16% and adalimumab 13%.

During the study period, 14 deaths (1.7%) were observed; being the cause cancer-related (n=5), infection (n=5), the disease itself for which was receiving biological treatment (n=2), and endocrine metabolic causes (n=2).

At the end of the review, 48% of the treatments were still in use, while 52% had stopped for various reasons: 20% ineffectiveness, 12% side effects, 12% maintained complete remission. The remaining low percentage was due to death, pregnancy, or study entry.

The side effects that led to a change in treatment was: non-immune hematological disorders in 4.1% (14% of tocilizumab, 7% of rituximab and 6% of vedolizumab), immune disorders in 3.8% (6% of secukinumab, 5% of tocilizumab and 4.5% of certolizumab), nervous system involvement in 2.4% (11.5% of golimumab,10% of abatacept, 5% of tocilizumab), debut or worsening of heart failure in 1.4% (9, 5% of tocilizumab, 2.5% of etanercept and 1.4% of adalimumab) and cancer-related in 0.7% (2% of infliximab, 1.7% of etanercept).

Conclusion:

In these 10 years of follow-up and and evaluating 847 treatments, there were 10% hospitalizations due to infections (n = 86) causing death in 5 patients. In light of these results, and pending an exhaustive statistical analysis, we did not find high frequencies of serious side effects in our series. Very little long-term evidence exists on the safety of these drugs.

References:

[1]Singh JA, Wells GA, Christensen R, et al. Adverse effects of biologics: a network meta-analysis and Cochrane overview. Cochrane Database Syst Rev. 2011;2011(2):CD008794. Published 2011 Feb 16.

Disclosure of Interests:

None declared.

Block-spiral magnetism: An exotic type of frustrated order

Competing interactions in quantum materials induce exotic states of matter such as frustrated magnets, an extensive field of research from both the theoretical and experimental perspectives. Here, we show that competing energy scales present in the low-dimensional orbital-selective Mott phase (OSMP) induce an exotic magnetic order, never reported before. Earlier neutron-scattering experiments on iron-based 123 ladder materials, where OSMP is relevant, already confirmed our previous theoretical prediction of block magnetism (magnetic order of the form [Formula: see text]). Now we argue that another phase can be stabilized in multiorbital Hubbard models, the block-spiral state. In this state, the magnetic islands form a spiral propagating through the chain but with the blocks maintaining their identity, namely rigidly rotating. The block-spiral state is stabilized without any apparent frustration, the common avenue to generate spiral arrangements in multiferroics. By examining the behavior of the electronic degrees of freedom, parity-breaking quasiparticles are revealed. Finally, a simple phenomenological model that accurately captures the macroscopic spin spiral arrangement is also introduced, and fingerprints for the neutron-scattering experimental detection are provided.

International Nosocomial Infection Control Consortium (INICC) report, data summary of 45 countries for 2012-2017: Device-associated module

BACKGROUND

We report the results of International Nosocomial Infection Control Consortium (INICC) surveillance study from January 2012 to December 2017 in 523 intensive care units (ICUs) in 45 countries from Latin America, Europe, Eastern Mediterranean, Southeast Asia, and Western Pacific.

METHODS

During the 6-year study period, prospective data from 532,483 ICU patients hospitalized in 242 hospitals, for an aggregate of 2,197,304 patient days, were collected through the INICC Surveillance Online System (ISOS). The Centers for Disease Control and Prevention-National Healthcare Safety Network (CDC-NHSN) definitions for device-associated health care-associated infection (DA-HAI) were applied.

RESULTS

Although device use in INICC ICUs was similar to that reported from CDC-NHSN ICUs, DA-HAI rates were higher in the INICC ICUs: in the medical-surgical ICUs, the pooled central line-associated bloodstream infection rate was higher (5.05 vs 0.8 per 1,000 central line-days); the ventilator-associated pneumonia rate was also higher (14.1 vs 0.9 per 1,000 ventilator-days,), as well as the rate of catheter-associated urinary tract infection (5.1 vs 1.7 per 1,000 catheter-days). From blood cultures samples, frequencies of resistance, such as of Pseudomonas aeruginosa to piperacillin-tazobactam (33.0% vs 18.3%), were also higher.

CONCLUSIONS

Despite a significant trend toward the reduction in INICC ICUs, DA-HAI rates are still much higher compared with CDC-NHSN's ICUs representing the developed world. It is INICC's main goal to provide basic and cost-effective resources, through the INICC Surveillance Online System to tackle the burden of DA-HAIs effectively.

Morphological, biochemical and functional studies to evaluate bovine oocyte vitrification

The aim of the present study was to evaluate the effect of vitrification on morphological, biochemical and functional parameters of matured bovine oocytes at different recovery times. To this end, matured bovine oocytes were vitrified using the Cryotech® kit (a minimum-volume system) and then incubated in maturation medium for different post-warming durations (0 h, 3 h or 21 h). Morphology, viability and biochemical parameters were assessed at each time point mentioned above and the recovery of the metaphase plate was analyzed at 2 h, 3 h and 4 h post-warming. The vitrification-warming process did not affect the viability or morphology of oocytes at any time point. However, the recovery of the metaphase plate occurred mostly between 3 and 4 h rather than at 2 h after warming (P < 0.05). Both control and vitrified-warmed oocytes showed changes in cytosolic oxidative activity, quantification of active mitochondria, reactive oxygen species (ROS) levels and redox status at the different time points studied (P < 0.05). However, differences between control and vitrified-warmed oocytes were found only in the quantification of active mitochondria and ROS production (P < 0.05). Finally, in vitro fertilization and embryo culture were carried out as functional studies to establish whether vitrification-warming affected oocyte competence, and a significant decrease was found both in the cleavage rate and embryo development (P < 0.05). We concluded that major improvements in oocyte vitrification, at list with Cryotech® kit, are still needed to avoid variations in oocyte metabolism which could contribute to the reduction in the developmental competence of bovine oocytes.

Novel Magnetic Block States in Low-Dimensional Iron-Based Superconductors

Inelastic neutron scattering recently confirmed the theoretical prediction of a ↑↑↓↓-magnetic state along the legs of quasi-one-dimensional iron-based ladders in the orbital-selective Mott phase (OSMP). We show here that electron doping of the OSMP induces a whole class of novel block states with a variety of periodicities beyond the previously reported π/2 pattern. We discuss the magnetic phase diagram of the OSMP regime that could be tested by neutrons once appropriate quasi-1D quantum materials with the appropriate dopings are identified.

Computing Resonant Inelastic X-Ray Scattering Spectra Using The Density Matrix Renormalization Group Method

We present a method for computing the resonant inelastic x-ray scattering (RIXS) spectra in one-dimensional systems using the density matrix renormalization group (DMRG) method. By using DMRG to address this problem, we shift the computational bottleneck from the memory requirements associated with exact diagonalization (ED) calculations to the computational time associated with the DMRG algorithm. This approach is then used to obtain RIXS spectra on cluster sizes well beyond state-of-the-art ED techniques. Using this new procedure, we compute the low-energy magnetic excitations observed in Cu L-edge RIXS for the challenging corner shared CuO4 chains, both for large multi-orbital clusters and downfolded t-J chains. We are able to directly compare results obtained from both models defined in clusters with identical momentum resolution. In the strong coupling limit, we find that the downfolded t-J model captures the main features of the magnetic excitations probed by RIXS only after a uniform scaling of the spectra is made.

Clinical anxiety promotes excessive response inhibition

BACKGROUND

Laboratory tasks to delineate anxiety disorder features are used to refine classification and inform our understanding of etiological mechanisms. The present study examines laboratory measures of response inhibition, specifically the inhibition of a pre-potent motor response, in clinical anxiety. Data on associations between anxiety and response inhibition remain inconsistent, perhaps because of dissociable effects of clinical anxiety and experimentally manipulated state anxiety. Few studies directly assess the independent and interacting effects of these two anxiety types (state v. disorder) on response inhibition. The current study accomplished this goal, by manipulating state anxiety in healthy and clinically anxious individuals while they complete a response inhibition task.

METHOD

The study employs the threat-of-shock paradigm, one of the best-established manipulations for robustly increasing state anxiety. Participants included 82 adults (41 healthy; 41 patients with an anxiety disorder). A go/nogo task with highly frequent go trials was administered during alternating periods of safety and shock threat. Signal detection theory was used to quantify response bias and signal-detection sensitivity.

RESULTS

There were independent effects of anxiety and clinical anxiety on response inhibition. In both groups, heightened anxiety facilitated response inhibition, leading to reduced nogo commission errors. Compared with the healthy group, clinical anxiety was associated with excessive response inhibition and increased go omission errors in both the safe and threat conditions.

CONCLUSIONS

Response inhibition and its impact on go omission errors appear to be a promising behavioral marker of clinical anxiety. These results have implications for a dimensional view of clinical anxiety.

Spectral functions with the density matrix renormalization group: Krylov-space approach for correction vectors

Frequency-dependent correlations, such as the spectral function and the dynamical structure factor, help illustrate condensed matter experiments. Within the density matrix renormalization group (DMRG) framework, an accurate method for calculating spectral functions directly in frequency is the correction-vector method. The correction vector can be computed by solving a linear equation or by minimizing a functional. This paper proposes an alternative to calculate the correction vector: to use the Krylov-space approach. This paper then studies the accuracy and performance of the Krylov-space approach, when applied to the Heisenberg, the t-J, and the Hubbard models. The cases studied indicate that the Krylov-space approach can be more accurate and efficient than the conjugate gradient, and that the error of the former integrates best when a Krylov-space decomposition is also used for ground state DMRG.

Spin Andreev-like reflection in metal-Mott insulator heterostructures

Using the time-dependent density-matrix renormalization group (tDMRG), we study the time evolution of electron wave packets in one-dimensional (1D) metal-superconductor heterostructures. The results show Andreev reflection at the interface, as expected. By combining these results with the well-known single-spin-species electron-hole transformation in the Hubbard model, we predict an analogous spin Andreev reflection in metal-Mott insulator heterostructures. This effect is numerically confirmed using 1D tDMRG, but it is expected to also be present in higher dimensions, as well as in more general Hamiltonians. We present an intuitive picture of the spin reflection, analogous to that of Andreev reflection at metal-superconductor interfaces. This allows us to discuss a novel antiferromagnetic proximity effect. Possible experimental realizations are discussed.

[Natural history of an optic disc macroaneurysm]

CASE REPORT

A 75-year old man with reduced vision in his left eye (0.05) presented with hypertensive retinopathy, retinal haemorrhages and cotton wool spots in the papillomacular bundle, as well as macular oedema. Fluorescein angiography showed a saccular hyperfluorescent lesion corresponding to arterial macroaneurysm on the optic disc, with the optical coherence tomography demonstrating macular oedema. At 2 months follow-up, vision had improved to 0.7 with spontaneous closure of the macroaneurysm and resolution of the macular oedema.

DISCUSSION

Arterial macroaneurysms on the optic disc are unusual and are difficult to diagnose clinically. There is no safe and effective treatment, and our case, as the few single cases reported, showed that they can spontaneously close and enable visual function to recover.

Elastic energy of the discocyte-stomatocyte transformation

The aim of this study is to calculate the membrane elastic energy for the different shapes observed in the discocyte-stomatocyte sequence. This analysis can provide a better quantitative understanding of the hypothesis put forward over the last decades to explain how red blood cells produce and maintain their typical shape. For this purpose, we use geometrical models based on parametric equations. The energy model considered for the elastic properties of RBC membrane includes the local and nonlocal resistance effects of the bilayer to bending. In particular, the results confirm the discocyte as the lowest energy value configuration among the sets of different red blood cell deformations considered in the sequence.

Time evolution with the density-matrix renormalization-group algorithm: a generic implementation for strongly correlated electronic systems

A detailed description of the time-step-targeting time evolution method within the density-matrix renormalization-group algorithm is presented. The focus of this publication is on the implementation of the algorithm and its generic application. The case of one-site excitations within a Hubbard model is analyzed as a test for the algorithm, using open chains and two-leg ladder geometries. The accuracy of the procedure in the case of the recently discussed holon-doublon photo excitations of Mott insulators is also analyzed. Performance and parallelization issues are discussed. In addition, the full open-source code is provided as supplementary material.