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According to perturbation theory predictions, QCD matter in the zero-temperature, high-density limits of QCD at nonzero isospin chemical potential is expected to be in a superfluid Bardeen-Cooper-Schrieffer (BCS) phase of u and d¯ Cooper pairs. It is also expected, on symmetry grounds, that such phase connects via an analytical crossover to the phase with Bose-Einstein condensation (BEC) of charged pions at μI≥mπ/2. With lattice results, showing some indications that the deconfinement crossover also smoothly penetrates the BEC phase, the conjecture was made that the former connects continuously to the BEC-BCS crossover. We compute the spectrum of the Dirac operator, and use generalized Banks-Casher relations, to test this conjecture and identify signatures of the superfluid BCS phase.
Background: Dexamethasone (Dex) is the most common corticosteroid to treat edema in glioblastoma (GBM) patients. Recent studies identified the addition of Dex to radiation therapy (RT) to be associated with poor survival. Independently, Tumor Treating Fields (TTFields) provides a novel anti-cancer modality for patients with primary and recurrent GBM. Whether Dex influences the efficacy of TTFields, however, remains elusive.
Methods: Human GBM cell lines MZ54 and U251 were treated with RT or TTFields in combination with Dex and the effects on cell counts and cell death were determined via flow cytometry. We further performed a retrospective analysis of GBM patients with TTFields treatment +/- concomitant Dex and analysed its impact on progression-free (PFS) and overall survival (OS).
Results: The addition of Dex significantly reduced the efficacy of RT in U251 and MZ54 cells. TTFields (200 kHz/250 kHz) induced massive cell death in both cell lines. Concomitant treatment of TTFields and Dex did not reduce the overall efficacy of TTFields. Further, in our retrospective clinical analysis, we found that the addition of Dex to TTFields therapy did not influence PFS nor OS.
Conclusion: Our translational investigation indicates that the efficacy of TTFields therapy in patients with GBM and primary GBM cell lines is not affected by the addition of Dex.
Study Design: Cross-sectional survey
Objective: To determine the influence of surgeons’ level of experience and subspeciality training on the reliability, reproducibility, and accuracy of sacral fracture classification using the AO Spine Sacral Injury Classification System.
Summary of Background Data: An ideal classification system is easily comprehensible and reliable amongst the diverse group of surgeons. A surgeons’ level of experience may have a significant effect on the reliability and accuracy of a classification system. Moreover, surgeons of different subspecialities may have various levels of comfort with imaging assessment of sacral injuries required for accurate diagnosis and classification.
Methods: High-resolution computerized tomography (CT) images from 26 cases were assessed by 172 investigators from a diverse array of surgical subspecialities (general orthopaedics, neurosurgery, orthopaedic spine, orthopaedic trauma) and experience (<5, 5-10, 11-20, >20 years). Validation assessments were performed via web conference using high-resolution images, as well as axial/sagittal/coronal CT scan sequences. Two assessments were performed by each investigator independently three weeks apart in randomized order. Reliability and reproducibility were calculated with cohen’s kappa coefficient (k) and gold standard classification agreement was determined for each fracture morphology and subtype and stratified by experience and subspeciality.
Results: Respondents achieved an overall k = 0.87 for morphology and k = 0.77 for subtype classification, representing excellent and substantial intraobserver reproducibility, respectively. Respondents from all four practice experience groups demonstrated excellent interobserver reliability when classifying overall morphology (k=0.842/0.850, Assessment 1/Assessment 2) and substantial interobserver reliability in overall subtype (k=0.719/0.751) in both assessments. General orthopaedists, neurosurgeons, and orthopaedic spine surgeons exhibited excellent interobserver reliability in overall morphology classification and substantial interobserver reliability in overall subtype classification. Surgeons in each experience category and subspecialty correctly classified fracture morphology in over 90% of cases and fracture subtype in over 80% of cases according to the gold standard. Correct overall classification of fracture morphology (Assessment 1: p= 0.024, Assessment 2: p=0.006) and subtype (p2<0.001) differed significantly with surgeons with >20 years of experience demonstrating increased difficulty correctly classifying all fracture subtypes overall in comparison to the other experience groups. Correct overall classification did not significantly differ by subspecialty.
Conclusions: Overall, the AO Spine Sacral Injury Classification System appears to be universally applicable among surgeons of various subspecialties and levels of experience with acceptable reliability, reproducibility, and accuracy.
Disclosures: author 1: none; author 2: consultant=Medtronic, Nuvasive, ISD, Asutra, Stryker, Bioventus, Zimmer, teledocs, Clinical Spine Surgery, AOSpine ; author 3: none; author 4: grants/research support=AOSpine, consultant=DPS, icotec; author 5: none; author 6: none; author 7: grants/research support=DPS; author 8: none; author 9: grants/research support=NIH, RTI, CSRS, royalties=Inion ; author 10: stock/shareholder=Advanced Spinal Intellectual Properties; Atlas Spine; Avaz Surgical; Bonovo Orthopaedics; Computational Biodynamics; Cytonics; Deep Health; Dimension Orthotics LLC; Electrocore; Flagship Surgical; FlowPharma; Globus; Innovative Surgical Design; Insight Therapeutics; Jushi; Nuvasive; Orthobullets; Paradigm Spine; Parvizi Surgical Innovation; Progressive Spinal Technologies; Replication Medica; Spine Medica; Spineology; Stout Medical; Vertiflex; ViewFi Health, royalties=Aesculap; Atlas Spine; Globus; Medtronics; SpineWave; Stryker Spine,other financial report=AO Spine
We empirically investigate algorithms for solving Connected Components in the external memory model. In particular, we study whether the randomized O(Sort(E)) algorithm by Karger, Klein, and Tarjan can be implemented to compete with practically promising and simpler algorithms having only slightly worse theoretical cost, namely Borůvka’s algorithm and the algorithm by Sibeyn and collaborators. For all algorithms, we develop and test a number of tuning options. Our experiments are executed on a large set of different graph classes including random graphs, grids, geometric graphs, and hyperbolic graphs. Among our findings are: The Sibeyn algorithm is a very strong contender due to its simplicity and due to an added degree of freedom in its internal workings when used in the Connected Components setting. With the right tunings, the Karger-Klein-Tarjan algorithm can be implemented to be competitive in many cases. Higher graph density seems to benefit Karger-Klein-Tarjan relative to Sibeyn. Borůvka’s algorithm is not competitive with the two others.
In this contribution we report the status and plans of the open lattice initiative to generate and share new gauge ensembles using the stabilised Wilson fermion framework. The production strategy is presented in terms of a three stage plan alongside summaries of the data management as well as access policies. Current progress in completing the first stage of generating ensembles at four lattice spacings at the flavor symmetric point is given.
This work is focused on the anomalous skin effect in copper and how it affects the efficiency of copper-cavities in the temperature range 40-50 K. The quality factor Q of three coaxial cavities was measured over the temperature range from 10 K to room temperature in the experiment. The three coaxial cavities have the same structure, but different lengths, which correspond to resonant frequencies: around 100 MHz, 220 MHz and 340 MHz. Furthermore, the effects of copper-plating and additional baking in the vacuum oven on the quality factor Q are studied in the experiment. The motivation is to check the feasibility of an efficient, pulsed, ion linac, operated at cryogenic temperatures.
OPEN SCIENCE, VERSION 3.0: Breaking down barriers for equitable and efficient research communication
(2022)
Propranolol as a potentially novel treatment of arteriovenous malformations: from bench to bedside
(2022)
Background: Propranolol is a non-selective blocker of the β-adrenergic receptor and has been used for treatment of proliferative infantile hemangiomas. The vasoconstrictive and antiangiogenic effects of propranolol led us to explore its potential application for the treatment of AVMs.
Methods: AVM tissue was cultured after surgical resection in the presence of 100μM propranolol or solvent DMSO. After incubation for 72 hours, tissue was harvested for testing. The expression levels of SDF1α, CXCR4, VEGF and HIF-1 was measured by rt-PCR. Furthermore, data of patients in 2 vascular centres harboring AVM was retrospectively interrogated for a time period of 20 years. The database included information about hemorrhage, AVM size and antihypertensive medication. Descriptive analyses were performed, focusing on the risk of hemorrhage, size of the lesion at presentation and clinical follow-up in patients on β-blocker medication versus those who were not.
Results: Among 483 patients, 73 (15%) were under β-blocker-treatment. 48% AVMs presented with hemorrhage at diagnosis. Patients under β-blocker-treatment had a lower risk of hemorrhage at the time of diagnosis in a univariate analysis (p<0,0001;OR13). Patients under β-blocker-treatment showed a significant higher chance for a lower Spetzler-Martin-grade ≤III (p<0,0001;OR6,5) and a lower risk for the presence of an associated aneurysm (p<0,0001;OR3,6).
Multivariate analysis including Spetzler-Martin-Grading, young age ≤50, presence of associated aneurysm and β-blocker-treatment showed reduced risk for hemorrhage under β-blocker-treatment (p<0,01,OR0,2).
The expression of CXCR4 was suppressed by propranolol most likely through the HIF-1-pathways. The gene-expression of vasculogenesis factors was decreased in with propranolol incubated AVMs.
Conclusion: β-Blocker medication seems to be associated with a decreased risk of AVM-related hemorrhage and AVM-size at presentation or during follow-up. Propranolol inhibits SDF1α-induced vasculogenesis by suppressing the expression of CXCR4 most likely through the HIF-1-pathways. Therefore, SDF1α/CXCR4 axis plays an important role in the vasculogenesis and migration of inflammatory cells in AVM lesions.
Background: During the COVID-19 pandemic, decreased volumes of acute stroke admissions were reported. We aimed to examine whether subarachnoid hemorrhage (SAH) volumes demonstrated similar declines in our department. Furthermore, the impact of pandemic on disease progression should be analyzed.
Methods: We conducted a retrospective study in neurosurgical department of university hospital Frankfurt including patients with the diagnosis of aneurysmal SAH during the first year of COVID-pandemic. One year cumulative volume for SAH hospitalization procedures were compared to the one-year period before (03/2020–02/2021 versus 03/2019–02/2020) and the last 5 pre-COVID-pandemic years (2015-2020). All relevant patient characteristics concerning family history, disease history, clinical condition at admission, active/past COVID-infection, treatment management, complications and outcome were analyzed.
Results: There was a decline in SAH hospitalizations, with 84 admissions in the year immediately before and 56 admissions during the pandemic, without reaching a significance. No significant difference in analyzed patient characteristics including clinical condition at onset, treatment, complications and outcome, between 56 SAH patients admitted during COVID pandemic and treated patients in the last 5 years in pre-COVID period were found. Using a multivariable analysis, we detected young age (p<0.05;OR4,2) and no existence of early hydrocephalus (p<0.05;OR0,13) as important factors for a favorable outcome (mRS≤0-2) after aSAH during the COVID-pandemic. A past COVID-infection was detected in young patients suffering from aSAH (Age< 50years, p<0.05;OR10,5) with increased rate of cerebral vasospasm after SAH onset (p<0.05;OR26). Nevertheless, past COVID-infection did not reach a significance as a high risk factor for unfavorable outcome.
Conclusion: There was a relative decrease in the volume of SAH during the COVID-19 pandemic. Despite of extremely different conditions of hospitalization, there was no impairing significant effect on treatment and outcome of admitted SAH patients. A past COVID-infection seemed not to be a relevant limiting factor concerning favorable outcome.
Background: Following elective craniotomy patients routinely receive monitoring on ICU. However, the benefit of ICU monitoring in these patients is discussed controversially. Due to the current COVID-19 pandemic, there are further limitations of ICU capacities. This study aimed to compare this strategy with a standardized management of post-craniotomy patients on ICU.
Methods: Two postoperative strategies were compared in a matched-pair analysis: The first cohort included patients treated between May-August 2021 according to the “No ICU – unless” concept (NIU group), where patients were managed on the normal ward postoperatively. The second cohort contained patients routinely admitted to the ICU between February-April 2021 (control group). Outcome parameters contained complications, length of stay, duration to first postoperative mobilization, number of unplanned imaging, number/type of ICU interventions and pre- and postoperative mRS. Patient characteristics were analyzed using electronic medical records.
Results: The NIU group consisted of 96 patients, the control group of 75 patients. Complication rates were comparable in both cohorts (16% in NIU vs. 17% in control; p=0.123). Groups did not differ significantly in the number of imaging (10% in NIU vs. 13% in control; p=0.67), in the type of interventions on ICU (antihypertensive therapy 5% (NIU) vs. 6% (control); p=0.825) or in the time to first postoperative mobilization (average 1.1± 1.6 days vs. 0.9± 1.2 days; p=0.402). Length of hospital stay was shorter in the NIU group without reaching statistical significance (average 5.8 vs. 6.8 days; p=0.481). There was no significant change in the distribution of preoperative (p=0.960) and postoperative (p=0.425) mRS scores.
Conclusion: Postoperative ICU management does not reduce postoperative complications and has no effect on the surgical outcome of elective craniotomies. The majority of postoperative complications are detected after a 24-hour observation period. This approach may represent a potential strategy to prevent overutilization of ICU capacities while maintaining sufficient postoperative care for neurosurgical patients.
Background: A growing interest exists in using polymeric nanoparticles (NPs) especially functionalized with surface-active substances as carriers across the blood brain barrier (BBB) for potentially effective drugs in traumatic brain injury (TBI). However, the organ distribution of intravenous administrated biodegradable and non-biodegradable NPs coated with different surfactants, how much of the administrated dose reach the brain parenchyma in areas with intact and opened BBB after trauma, as well as whether they elicit an inflammatory response is still to be clarified.
Methods: The organ distribution, brain penetration and eventual inflammatory activation of polysorbate-80 (Tw80) and sodium-lauryl-sulfate (SDS) coated poly l-lactide (PLLA) and perfluorodecyl acrylate (PFDL) nanoparticles were evaluated after intravenous administration in rats prior and after undergoing controlled cortical impact (CCI).
Results: A significant highest NP uptake at 4 and 24 hs was observed in the liver and spleen, followed by the brain and kidney, with minimal concentrations in the lungs and heart for all NPs. After CCI, a significant increase of NP uptake at 4 hs and 24 hs was observed within the traumatized hemisphere, especially in the perilesional area, although NPs were still found in areas away from CCI and the contralateral hemisphere in similar concentrations as in non-CCI subject. NPs were localized in neurons, glial and endovascular cells. Immunohistochemical staining against GFAP, Iba1, TNFα and IL1β demonstrated no glial activation or neuroinflamatory changes.
Conclusions: Tw80 and SDS coated biodegradable (PLLA) and non-biodegradrable (PFDL) NPs reach the brain parenchyma in both areas of traumatized and undamaged brain with disrupted and intact BBB, even though a high amount of them are retained in the liver and the spleen. No inflammatory reaction is elicited by these NPs within 24 hs after application. These preliminary promising results postulate the effectiveness and safety of these NPs as drug-carriers for the treatment of TBI.
Background: The most frequent therapy of hydrocephalus is the implantation of ventriculoperitoneal shunts for diverting cerebrospinal fluid from the ventricles into the peritoneum. We compared two adjustable valves, the proGAV and proGAV 2.0, for complications which resulted in revision operations.
Methods: Four hundred patients who underwent primary shunt implantation between 2014 and 2020 were analyzed for overall revision rate, one-year revision rate, revision free survival and overall survival observing patient age group, gender, etiology of hydrocephalus, implantation site, prior diversion of cerebrospinal fluid and cause of revision.
Results: All data were available of all 400 patients (female/male 208/192). Overall, 99 patients underwent revision surgery after primary implantation. ProGAV valve was implanted in 283 patients, proGAV 2.0 in 117 patients. There was no significant difference between the two shunt valves concerning revision rate (p=0.8069), one-year revision rate (p=0.9077), revision free survival (p=0.6921) and overall survival (p=0.3232). Furthermore, regarding one-year revision rate, we observed no significant difference between the two shunt valves in pediatric patients (40.7% vs 27.6%; p=0.2247). Revision operation had to be performed more frequently in pediatric patients (46.6% vs 24.8%; p=0.0093) with a significant higher number of total revisions with proGAV than proGAV 2.0 (55.9% vs. 27.6%; p=0.0110) most likely due to longer follow up in the proGAV -group.
Conclusion: According to the target variables we analyzed, aside from lifetime revision rate in pediatric patients there is no significant difference between the two shunt valves. From our subjective point of view, implantation of the newer proGAV 2.0 valve is preferable due to higher adjustment comfort for both patients and physicians.
In this work we study the 3+1-dimensional Nambu-Jona-Lasinio (NJL) model in the mean field-approximation. We carry out calculations using five different regularization schemes (two continuum and three lattice regularization schemes) with particular focus on inhomogeneous phases and condensates. The regularization schemes lead to drastically different inhomogeneous regions. We provide evidence that inhomogeneous condensates appear for all regularization schemes almost exclusively at values of the chemical potential and with wave numbers, which are of the order of or even larger than the corresponding regulators. This can be interpreted as indication that inhomogeneous phases in the 3+1-dimensional NJL model are rather artifacts of the regularization and not a consequence of the NJL Lagrangian and its symmetries.
We refine our previous study of a udb¯b¯ tetraquark resonance with quantum numbers I(JP)=0(1−), which is based on antiheavy-antiheavy lattice QCD potentials, by including heavy quark spin effects via the mass difference of the B and the B∗ meson. This leads to a coupled channel Schrödinger equation, where the two channels correspond to BB and B∗B∗, respectively. We search for T matrix poles in the complex energy plane, but do not find any indication for the existence of a tetraquark resonance in this refined coupled channel approach. We also vary the antiheavy-antiheavy potentials as well as the b quark mass to further understand the dynamics of this four-quark system.
Effective three-dimensional Polyakov loop theories derived from QCD by strong coupling and hopping expansions are valid for heavy quarks and can also be applied to finite chemical potential μ, due to their considerably milder sign problem. We apply the Monte-Carlo method to the Nf=1,2 effective theories up to O(κ4) in the hopping parameter at μ=0 to determine the critical quark mass, at which the first-order deconfinement phase transition terminates. The critical end point obtained from the effective theory to order O(κ2) agrees well with 4-dimensional QCD simulations with a hopping expanded determinant by the WHOT-QCD collaboration. We also compare with full QCD simulations and thus obtain a measure for the validity of both the strong coupling and the hopping expansion in this regime.
The STAR experiment provides a perfect machinery for studying strange matter for more than two decades. Recently, we developed the express procedure, which allows online monitoring of the collected physics data. The high quality of express calibration and reconstruction provides a unique possibility to run the express production and observe almost in real time strange particles including mesons, hyperons, resonances and even hypernuclei.
The STAR Beam Energy Scan II program, including fixed target Au+Au collisions taken in 2018–2021, is particularly suited to study hypernuclei. Light hypernuclei are expected to be abundantly produced in low energy heavy-ion collisions. Measurements of hypernuclei production and their properties will provide information on the hyperon-nucleon interactions, which are essential ingredients for understanding nuclear matter equation of state at high net-baryon densities, such as inside neutron stars.
With the heavy fragment trigger introduced for the 2021 data taking, we were able to run the express production at the STAR High Level Trigger farm. The collected data were suffcient to observe the decay process of Λ5He →4Hepπ− with more than 11σ significance, measure binding energy as a function of hypernuclei mass, and study hypernuclei decay properties with the Dalitz plot technique.
We study the high temperature transition in pure SU(3) gauge theory and in full QCD with 3D-convolutional neural networks trained as parts of either unsupervised or semi-supervised learning problems. Pure gauge configurations are obtained with the MILC public code and full QCD are from simulations of Nf=2+1+1 Wilson fermions at maximal twist. We discuss the capability of different approaches to identify different phases using as input the configurations of Polyakov loops. To better expose fluctuations, a standardized version of Polyakov loops is also considered.
We present SU(3) lattice Yang-Mills data for hybrid static potentials from five ensembles with different small lattice spacings and the corresponding parametrizations for quark-antiquark separations 0.08fm≤r≤1.12fm. We remove lattice discretization errors at tree level of perturbation theory and partly at order a2 as well as the a-dependent self energy. In particular the tree-level improvement of static potentials is discussed in detail and two methods are compared. The resulting parametrizations are expected to represent continuum limit results for hybrid static potentials within statistical errors.
Gravitational-wave cosmology with dark sirens: state of the art and perspectives for 3G detectors
(2022)
A joint fit of the mass and redshift distributions of the population of Binary Black Holes detected with Gravitational-Wave observations can be used to obtain constraints on the Hubble parameter and on deviations from General Relativity in the propagation of Gravitational Waves. We first present applications of this technique to the latest catalog of Gravitational-Wave events, focusing on the comparison of different parametrizations for the source-frame mass distribution of Black Hole Binaries. We find that models with more than one feature are favourite by the data, as suggested by population studies, even when varying the cosmology. Then, we discuss perspectives for the use of this technique with third generation Gravitational-Wave detectors, exploiting the recently developed Fisher information matrix Python code GWFAST.
Study of I = 0 bottomonium bound states and resonances based on lattice QCD static potentials
(2022)
We investigate I=0 bottomonium bound states and resonances in S, P, D and F waves using lattice QCD static-static-light-light potentials. We consider five coupled channels, one confined quarkonium and four open B(∗)B¯(∗) and B(∗)sB¯(∗)s meson-meson channels and use the Born-Oppenheimer approximation and the emergent wave method to compute poles of the T matrix. We discuss results for masses and decay widths and compare them to existing experimental results. Moreover, we determine the quarkonium and meson-meson composition of these states to clarify, whether they are ordinary quarkonium or should rather be interpreted as tetraquarks.
The OpenLat initiative presents its results of lattice QCD simulations using Stabilized Wilson Fermions (SWF) using 2+1 quark flavors. Focusing on the SU(3) flavor symmetric point mπ=mK=412 MeV, four different lattice spacings (a=0.064,0.077,0.094,0.12 fm) are used to perform the continuum limit to study cutoff effects. We present results on light hadron masses; for the determination we use a Bayesian analysis framework with constraints and model averaging to minimize the bias in the analysis.
The thermodynamics of QCD with sufficiently heavy dynamical quarks can be described by a three-dimensional Polyakov loop effective theory, obtained after a truncated character and hopping expansion. We investigate the resulting phase diagram for low temperatures by mean field methods. Taking into account chemical potentials for both baryon number and isospin, we obtain clear signals for a liquid-gas type transition to baryon matter at μI=0 and a Bose-Einstein condensation transition at μB=0, as well as for their connection when both chemical potentials are non-zero.
Computation of masses of quarkonium bound states using heavy quark potentials from lattice QCD
(2022)
We compute masses of bottomonium and charmonium bound states using a Schrödinger equation with a heavy quark-antiquark potential including 1/m and 1/m2 corrections previously derived in potential Non-Relativistic QCD and computed with lattice QCD. This is a preparatory step for a future project, where we plan to take into account similar corrections to study quarkonium resonances and tetraquarks above the lowest meson-meson thresholds.
The global center symmetry of quenched QCD at zero baryonic chemical potential is broken spontaneously at a critical temperature Tc leading to a first-order phase transition. Including heavy dynamical quarks breaks the center symmetry explicitly and weakens the first-order phase transition for decreasing quark masses until it turns into a smooth crossover at a Z(2)-critical point. We investigate the Z(2)-critical quark mass value towards the continuum limit for Nf=2 flavors using lattice QCD in the staggered formulation. As part of a continued study, we present results from Monte-Carlo simulations on Nτ=8,10 lattices. Several aspect ratios and quark mass values were simulated in order to obtain the critical mass from a fit of the Polyakov loop to a kurtosis finite size scaling formula. Moreover, the possibility to develop a Ginzburg-Landau effective theory around the Z(2)-critical point is explored.
For the exploration of the phase diagram of QCD, effective Polyakov loop theories derived from lattice QCD provide a valuable tool in the heavy quark mass regime. In practice, the evaluation of these theories is complicated by the appearance of long-range and multipoint interaction terms. On the other hand, it is well known that for theories with such kind of interactions mean field approximations can be expected to yield reliable results. Here, we apply this framework to the critical endpoint of the deconfinement transition and results are compared to the literature. This treatment can also be used to investigate the phase diagram at non-zero baryon and isospin chemical potential.
Approaching the continuum limit of the deconfinement critical point for Nf=2 staggered fermions
(2022)
Quenched QCD at zero baryonic chemical potential undergoes a first-order deconfinement phase transition at a critical temperature Tc, which is related to the spontaneous breaking of the global center symmetry. The center symmetry is broken explicitly by including dynamical quarks, which weaken the first-order phase transition for decreasing quark masses. At a certain critical quark mass, which corresponds to the Z(2)-critical point, the first-order phase transition turns into a smooth crossover. We investigate the Z(2)-critical quark mass for Nf=2 staggered fermions on Nτ=8,10 lattices, where larger Nτ correspond to finer lattices. Monte-Carlo simulations are performed for several quark mass values and aspect ratios in order to extrapolate to the thermodynamic limit. We present final results for Nτ=8 and preliminary results for Nτ=10 for the critical mass, which are obtained from fitting to a kurtosis finite size scaling formula of the absolute value of the Polyakov loop.
The so-called Columbia plot summarises the order of the QCD thermal transition as a function of the number of quark flavours and their masses. Recently, it was demonstrated that the first-order chiral transition region, as seen for Nf∈[3,6] on coarse lattices, exhibits tricritical scaling while extrapolating to zero on sufficiently fine lattices. Here we extend these studies to imaginary baryon chemical potential. A similar shrinking of the first-order region is observed with decreasing lattice spacing, which again appears compatible with a tricritical extrapolation to zero.
In an ideal world, extraction of machine-readable data and knowledge from natural-language biodiversity literature would be done automatically, but not so currently. The BIOfid project has developed some tools that can help with important parts of this highly demanding task, while certain parts of the workflow cannot be automated yet. BIOfid focuses on the 20th century legacy literature, a large part of which is only available in printed form. In this workshop, we will present the current state of the art in mobilisation of data from our corpus, as well as some challenges ahead of us. Together with the participants, we will exercise or explain the following tasks (some of which can be performed by the participants themselves, while other tasks currently require execution by our specialists with special equipment): Preparation of text files as an input; pre-processing with TextImager/TextAnnotator; semiautomated annotation and linking of named entities; generation of output in various formats; evaluation of the output. The workshop will also provide an outlook for further developments regarding extraction of statements from natural-language literature, with the long-term aim to produce machine-readable data from literature that can extend biodiversity databases and knowledge graphs.
Recently, an approximate SU(4) chiral spin-flavour symmetry was observed in multiplet patterns of QCD meson correlation functions, in a temperature range above the chiral crossover. This symmetry is larger than the chiral symmetry of massless QCD, and can only arise effectively when colour-electric quark-gluon interactions dynamically dominate the quantum effective action. At temperatures about three times the crossover temperature, these patterns disappear again, indicating the screening of colour-electric interactions, and the expected chiral symmetry is recovered. In this contribution we collect independent evidence for such an intermediate temperature range, based on screening masses and the pion spectral function. Both kinds of observables behave non-perturbatively in this window, with resonance-like peaks for the pion and its first excitation disappearing gradually with temperature. Using symmetry arguments and the known behaviour of screening masses at small densities, we discuss how this chiral spin symmetric band continues into the QCD phase diagram.
n this joint contribution we announce the formation of the "OPEN LATtice initiative", this https URL, to study Stabilised Wilson Fermions (SWF). They are a new avenue for QCD calculations with Wilson-type fermions and we report results on our continued study of this framework: Tuning the clover improvement coefficient, and extending the reach of lattice spacings to a=0.12 fm. We fix the flavor symmetric points mπ=mK=412 MeV at a=0.055,0.064,0.077,0.094,0.12 fm and define the trajectories to the physical point by fixing the trace of the quark mass matrix. Currently our pion mass range extends down to mπ∼200 MeV. We outline our tuning goals and strategy as well as our future planned ensembles. First scaling studies are performed on fπ and mπ. Additionally results of a preliminary continuum extrapolation of mN at the flavor symmetric point are presented. Going further a first determination of the light and strange hadron spectrum chiral dependence is shown, which serves to check the quality of the action for precision measurements. We also investigate other quantities such as flowed gauge observables to study how the continuum limit is approached. Taken together we observe the SWF enable us to perform stable lattice simulations across a large range of parameters in mass, volume and lattice spacing. Pooling resources our new initiative has made our reported progress possible and through it we will share generated gauge ensembles under an open science philosophy.
We compute the equation of state of isospin asymmetric QCD at zero and non-zero temperatures using direct simulations of lattice QCD with three dynamical flavors at physical quark masses. In addition to the pressure and the trace anomaly and their behavior towards the continuum limit, we will particularly discuss the extraction of the speed of sound. Furthermore, we discuss first steps towards the extension of the EoS to small non-zero baryon chemical potentials via Taylor expansion.
The interrelation between quantum anomalies and electromagnetic fields leads to a series of non-dissipative transport effects in QCD. In this work we study anomalous transport phenomena with lattice QCD simulations using improved staggered quarks in the presence of a background magnetic field. In particular, we calculate the conductivities both in the free case and in the interacting case, analysing the dependence of these coefficients with several parameters, such as the temperature and the quark mass.
Stabilized Wilson fermions are a reformulation of Wilson clover fermions that incorporates several numerical stabilizing techniques, but also a local change of the fermion action - the original clover term being replaced with an exponentiated version of it. We intend to apply the stabilized Wilson fermions toolbox to the thermodynamics of QCD, starting on the Nf=3 symmetric line on the Columbia plot, and to compare the results with those obtained with other fermion discretizations.
We discuss results for the Roberge Weiss (RW) phase transition at nonzero imaginary baryon and isospin chemical potentials, in the plane of temperature and quark masses. Our study focuses on the light tricritical endpoint which has already been used as a starting point for extrapolations aiming at the chiral limit at vanishing chemical potentials. In particular, we are interested in determining how imaginary isospin chemical potential shifts the tricritical mass with respect to earlier studies at zero imaginary isospin chemical potential. A positive shift might allow one to perform the chiral extrapolations from larger quark mass values, therefore making them less computationally expensive. We also present results for the dynamics of Polyakov loop clusters across the RW phase transition.
We present first results of a recently started lattice QCD investigation of antiheavy-antiheavy-light-light tetraquark systems including scattering interpolating operators in correlation functions both at the source and at the sink. In particular, we discuss the importance of such scattering interpolating operators for a precise computation of the low-lying energy levels. We focus on the b¯b¯ud four-quark system with quantum numbers I(JP)=0(1+), which has a ground state below the lowest meson-meson threshold. We carry out a scattering analysis using Lüscher's method to extrapolate the binding energy of the corresponding QCD-stable tetraquark to infinite spatial volume. Our calculation uses clover u, d valence quarks and NRQCD b valence quarks on gauge-link ensembles with HISQ sea quarks that were generated by the MILC collaboration.
In this work, the phase diagram of the 2+1-dimensional Gross-Neveu model is investigated with baryon chemical potential as well as chiral chemical potential in the mean-field approximation. We study the theory using two lattice discretizations, which are both based on naive fermions. An inhomogeneous chiral phase is observed only for one of the two discretizations. Our results suggest that this phase disappears in the continuum limit.
Nitrogen pollution is a major constituent of global change, threatening local biodiversity, ecosystem services, and causing serious environmental damage. Specifically, in areas with heavy agricultural soil-use, excessive use of nitrogen fertilizer pollutes the groundwaters with nitrates, but also with ammonia and nitrites. Freshwater fish and other aquatic fauna are especially vulnerable to nitrites, which can cause massive mortalities at even low concentrations < 0.1 mg/l NO2- - N. Adaptation of fish to environments with relatively high concentrations of chemicals has occurred throughout the history of life, although contemporary evolution acts at a much more rapid pace. The growing use of land for mass agriculture and livestock industries in the last 50 years in Florida has dramatically increased the nutrient loading into the groundwaters that feed the springs. Nitrite poses a serious threat for freshwater fauna as it is rapidly up taken and disturbs ion homeostasis and blood gas transport in fish. In this study, we evaluated, by means of a common-garden experiment, the tolerance of fish to nitrite using three different populations of eastern mosquitofish (Gambusia holbrooki) with different background nitrogen pollution histories. Mosquitofish females were exposed to nitrite in the lab, to either < 0.005 mg/l NO2- (control) or 0.3 mg/l NO2- for ten days and we assessed at the end of the exposure period their blood O2 transport capacity by measuring the concentration of four different types of hemoglobin, their total hematocrit, and their respiratory rates. Preliminary results show slight but significant varying patterns in the response of the exposed fish, depending on the population source, as evidenced by their respiratory rates and the blood erythrocyte counts. Mortality was very low, and hemoglobin profiles indicate high tolerance of G. holbrooki to nitrite contamination – a factor supporting their invasion success in agriculturally dominated regions around the world.