The ground state of the toric code, that of the two-dimensional class D superconductor, and the partition sum of the two-dimensional Ising model are dual to each other. This duality is remarkable in as much as it connects systems commonly associated to different areas of physics—that of long-range entangled topological order, (topological) band insulators, and classical statistical mechanics, respectively. Connecting fermionic and bosonic systems, the duality construction is intrinsically nonlocal, a complication that has been addressed in a plethora of different approaches, including dimensional reduction to one dimension, conformal field theory methods, and operator algebra. In this paper, we propose a unified approach to this duality, whose main protagonist is a tensor network (TN) assuming the role of an intermediate translator. Introducing a fourth node into the net of dualities offers several advantages: the formulation is integrative in that all links of the duality are treated on an equal footing, (unlike in field theoretical approaches) it is formulated with lattice precision, a feature that becomes key in the mapping of correlation functions, and their possible numerical implementation. Finally, the passage from bosons to fermions is formulated entirely within the two-dimensional TN framework where it assumes an intuitive and technically convenient form. We illustrate the predictive potential of the formalism by exploring the fate of phase transitions, point and line defects, topological boundary modes, and other structures under the mapping between system classes. Having condensed-matter readerships in mind, we introduce the construction pedagogically in a manner assuming only minimal familiarity with the concept of TNs.
Weniger anzeigenIn order to examine the progressive chemical evolution of halogens (F, Cl, Br, I) in altered ocean crust (AOC) during prograde subduction, this study compares bulk and in situ halogen concentrations in mafic samples from three petrogenetically related exhumed terrains in the Western Alps (the Chenaillet ophiolite, the Queyras ophiolites of the Schistes Lustrés, and the Monviso ophiolite). Samples from the Chenaillet ophiolite represent oceanic crust unaffected by metamorphic halogen loss and define a protolith halogen content (122 μg/g F, 29 μg/g Cl, 82 ng/g Br, and 98 ng/g I). Samples from the Queyras ophiolites experienced blueschist facies conditions, undergoing recrystallization and halogen loss (74 μg/g F, 19 μg/g Cl, 70 ng/g Br, and 63 ng/g I). Eclogite facies samples from the Monviso meta-ophiolite exhibit markedly reduced Cl (8 μg/g Cl) and Br (42 ng/g Br) contents relative to samples from Chenaillet and Queyras. Using electron probe microanalysis (EPMA), F and Cl host minerals (e.g., amphibole, chlorite, epidote) are identified and characterized in selected samples, showing a broad distribution of F and Cl, lending support to the view that halogen devolatilization in the subducting slab occurs continuously and is not dependent on the breakdown of a particular phase. In situ Cl concentrations decrease significantly between sub-greenschist and blueschist assemblages. Fluorine is retained within subducting AOC and is decoupled from the heavy halogens (Cl, Br, I), which undergo continuous devolatilization during prograde metamorphism.
Weniger anzeigenQuantum repeaters have long been established to be essential for distributing entanglement over long distances. Consequently, their experimental realization constitutes a core challenge of quantum communication. However, there are numerous open questions about implementation details for realistic near-term experimental setups. In order to assess the performance of realistic repeater protocols, here we present ReQuSim, a comprehensive Monte Carlo–based simulation platform for quantum repeaters that faithfully includes loss and models a wide range of imperfections such as memories with time-dependent noise. Our platform allows us to perform an analysis for quantum repeater setups and strategies that go far beyond known analytical results: This refers to being able to both capture more realistic noise models and analyze more complex repeater strategies. We present a number of findings centered around the combination of strategies for improving performance, such as entanglement purification and the use of multiple repeater stations, and demonstrate that there exist complex relationships between them. We stress that numerical tools such as ours are essential to model complex quantum communication protocols aimed at contributing to the quantum Internet.
Weniger anzeigenThe manipulation of topologically ordered phases of matter to encode and process quantum information forms the cornerstone of many approaches to fault-tolerant quantum computing. Here we demonstrate that fault-tolerant logical operations in these approaches can be interpreted as instances of anyon condensation. We present a constructive theory for anyon condensation and, in tandem, illustrate our theory explicitly using the color-code model. We show that different condensation processes are associated with a general class of domain walls, which can exist in both spacelike and timelike directions. This class includes semitransparent domain walls that condense certain subsets of anyons. We use our theory to classify topological objects and design novel fault-tolerant logic gates for the color code. As a final example, we also argue that dynamical “Floquet codes” can be viewed as a series of condensation operations. We propose a general construction for realizing planar dynamically driven codes based on condensation operations on the color code. We use our construction to introduce a new Calderbank-Shor-Steane–type Floquet code that we call the Floquet color code.
Weniger anzeigenQuantum information processing architectures typically only allow for nearest-neighbor entanglement creation. In many cases, this prevents the direct generation of GHZ states, which are commonly used for many communication and computation tasks. Here, we show how to obtain GHZ states between nodes in a network that are connected in a straight line, naturally allowing them to initially share linear cluster states. We prove a strict upper bound of ⌊(n+3)/2⌋ on the size of the set of nodes sharing a GHZ state that can be obtained from a linear cluster state of n qubits, using local Clifford unitaries, local Pauli measurements, and classical communication. Furthermore, we completely characterize all selections of nodes below this threshold that can share a GHZ state obtained within this setting. Finally, we demonstrate these transformations on the IBMQ Montreal quantum device for linear cluster states of up to n=19 qubits.
Weniger anzeigenAgent-based vegetation models are a widely used tool in ecology, for example, to understand and predict the response of vegetation to environmental change. Models are based on well-established descriptions of processes such as vegetation establishment, growth and mortality. However, they are often developed from scratch, which can be inefficient. Here we present pyMANGA, a free and open-source platform for plant growth modelers. pyMANGA's modular design allows for the combination of different concepts and theories of how plants establish, grow or compete in response to above- and below-ground resource availability. New or alternative modules describing, e.g., competition or facilitation, can be easily added. The interchangeability of modules supports the systematic testing of different hypotheses, e.g., on dominant processes in soil-plant feedback loops. Here we further present the thorough benchmarking strategy to maintain the platform and how pyMANGA can be used to compare models with different levels of abstraction and complexity.
Weniger anzeigenInformation and communication technologies (ICTs) have been credited with the potential to alter the dynamics of environmental governance by empowering citizens, enhancing accountability and improving government efficiency. However, in non-democratic contexts the link between ICTs and public participation is far from clear. Taking the case of China, this study investigates urban Chinese citizens’ use of digital technologies for environmental participation and the factors explaining (non)engagement. Drawing on an online survey with 2912 participants in 2021, we find surprisingly high levels of participation that is not hampered by regime-related factors such as trust in governmental institutions or concerns about the risks of taking action online. This shows that digital technologies have significant participatory potential also under restrictive conditions. However, our findings also show several major limitations of ICTs. Participation in our study is driven by citizens who are digitally skilled, environmentally concerned and also active in the offline sphere. This points, first, to a digital participation opportunity gap that could exclude the less digitally skilled and tech-savvy. Second, this supports the “reinforcement hypothesis” that ICTs are used by the already active and do not suffice to draw new social groups into the policy process. Third, in our study digital environmental participation is limited by citizens’ attribution of responsibility to the government, an unintended consequence of China’s “environmental authoritarianism” that curtails ICTs from unfolding their full potential. Together, our findings contribute to the debate on digital authoritarianism and the opportunities and limitations of ICTs for environmental participation in non-democratic contexts.
Weniger anzeigenWe study optimal minimum degree conditions when an n -vertex graph G contains an r -regular r -connected spanning subgraph. We prove for r fixed and n large the condition to be delta(G) >= n+r-2 / 2 when nr equivalent to 0 (mod 2). This answers a question of M. Kriesell.
Epidemiological modeling has a long history and is often used to forecast the course of infectious diseases or pandemics. These models come in different complexities, ranging from systems of simple ordinary differential equations (ODEs) to complex agent-based models (ABMs). The former allow a fast and straightforward optimization, but are limited in accuracy, detail, and parameterization, while the latter can resolve spreading processes in detail, but are extremely expensive to optimize. Epidemiological modeling can also be used to propose and design non-pharmaceutical interventions such as lockdowns. In general, their optimal design often leads to nonlinear optimization problems. We consider policy optimization in a prototypical situation modeled as both ODE and ABM, review numerical optimization approaches, and propose a heterogeneous multilevel approach based on combining a fine-resolution ABM and a coarse ODE model. Numerical experiments, in particular with respect to convergence speed, are given for illustrative examples.
Weniger anzeigenThe genus Wetmoreana was studied using quantitative integrative taxonomy methods to resolve the genus delimitation and explore its taxonomy diversity at the species level. As a result, the genus Fulgogasparrea is synonymized with Wetmoreana, and the latter includes 15 formally described species, one subspecies, and three further, thus far undescribed species: W. appressa, W. awasthii comb. nov., W. bahiensis sp. nov., W. brachyloba comb. nov., W. brouardii, W. chapadensis comb. nov., W. circumlobata sp. nov., W. decipioides, W. intensa comb. nov., W. ochraceofulva comb. nov., W. rubra sp. nov., W. sliwae sp. nov., W. sliwae ssp. subparviloba subsp. nov., W. subnitida comb. nov., W. texana, and W. variegata sp. nov. Eleven of 19 examined taxa are newly placed within this genus or confirmed to belong to it. Two species, W. awasthii and W. intensa, are transferred to Wetmoreana without additional analysis but based on previous studies. The W. brouardii and W. ochraceofulva species complexes are discussed in detail. Additionally, Caloplaca muelleri and C. rubina var. evolutior are transferred to Squamulea, and the latter is elevated to the species rank.
Weniger anzeigenMotivation
The minimizer concept is a data structure for sequence sketching. The standard canonical minimizer selects a subset of k-mers from the given DNA sequence by comparing the forward and reverse k-mers in a window simultaneously according to a predefined selection scheme. It is widely employed by sequence analysis such as read mapping and assembly. k-mer density, k-mer repetitiveness (e.g. k-mer bias), and computational efficiency are three critical measurements for minimizer selection schemes. However, there exist trade-offs between kinds of minimizer variants. Generic, effective, and efficient are always the requirements for high-performance minimizer algorithms.
Results
We propose a simple minimizer operator as a refinement of the standard canonical minimizer. It takes only a few operations to compute. However, it can improve the k-mer repetitiveness, especially for the lexicographic order. It applies to other selection schemes of total orders (e.g. random orders). Moreover, it is computationally efficient and the density is close to that of the standard minimizer. The refined minimizer may benefit high-performance applications like binning and read mapping.
Availability and implementation
The source code of the benchmark in this work is available at the github repository https://github.com/xp3i4/mini_benchmark
Weniger anzeigenAlterations in thyroid hormones (TH) and thyroid-stimulating hormone levels are frequently found following exposure to chemicals of concern. Dysregulation of TH levels can severely perturb physiological growth, metabolism, differentiation, homeostasis in the adult and developmental processes in utero. A frequently identified mode of action for this interaction is the induction of hepatic detoxification mechanisms (e.g. SULTs and UGTs), which lead to TH conjugation and elimination and therefore interfere with hormonal homeostasis, fulfilling the endocrine disruptors (EDs) definition. A short-term study in rats with dietary exposure to cyproconazole, epoxiconazole and prochloraz was conducted and hepatocyte hypertrophy, hepatic UGT activity and Phase 1/2 gene expression inductions were observed together with changes in TH levels and thyroid follicular hypertrophy and hyperplasia. To test for specific interaction with the thyroid hormone system, in vitro assays were conducted covering thyroidal I-uptake (NIS), TH transmembranal transport via MCT8 and thyroid peroxidase (TPO) function. Assays for iodothyronine deiodinases (DIO1–DIO3) and iodotyrosine deiodinase (DEHAL1) were included, and from the animal experiment, Dio1 and Dehal1 activities were measured in kidney and liver as relevant local indicators and endpoints. The fungicides did not affect any TH-specific KEs, in vitro and in vivo, thereby suggesting hepatic conjugation as the dominant MoA.
Weniger anzeigenJayme Tiomno belonged to the ‘founder’s generation’ of physicists in Brazil. He began working in relativity theory early in his career, at a time when it was not at all ‘fashionable’, through the influence of his early mentor, Mario Schenberg in São Paulo. When he went to graduate school in Princeton, in February 1948, his advisor there, John Wheeler, gave him a project in General Relativity, even though this was more than 4 years before Wheeler’s ‘turn’ from nuclear and particle physics to field theory and gravitation.
Tiomno and Wheeler however soon discovered their mutual interest in meson decays, and Tiomno’s Masters and PhD theses were on topics from particle physics, which remained his major field of interest for the following 20 years, during which he collaborated with Abdus Salam, among others. Only when he returned to Princeton in 1971, a refugee from the oppressive dictatorship in Brazil, did he again begin working in gravitation and field theory, having missed the ‘golden age’ initiated in part by Wheeler’s group.
At the IAS, Tiomno experienced a renaissance of his interest in field theory, working with Remo Ruffini and others. He continued this work in the 1980’s after he was able to return to the CBPF in Rio de Janeiro (which he had helped to found). His participation in the Marcel Grossmann Meetings was limited but significant.
Weniger anzeigenMetal-organic frameworks (MOFs) are crystalline and porous, molecular solids consisting of metal nodes and organic ligands. An interesting example is the MOF-2 system, where Cu2+ ions form antiferromagnetically coupled dimers to yield so-called paddlewheels. In the case of surface-anchored MOF-2 (SURMOF-2) systems the Cu2+ ions are connected via carboxylate and OH groups in a zipperlike fashion. This unusual coupling of the spin-1/2 ions within the resulting one-dimensional chains stabilizes a low-temperature ferromagnetic (FM) phase. In this study, the magnetic properties of two SURMOF-2 systems (Cu(bdc) and Cu(bpdc) with bdc=1, 4-benzendicarboxylic acid, bpdc=4,4-biphenyldicarboxylic acid) were investigated using x-ray magnetic circular dichroism both in the absorption and in the scattering geometry. The presence of the FM phase in these SURMOF-2 systems is confirmed. Taking advantage of the element sensitivity of this technique. it was established that the magnetic signal originates from Cu2+ ions. After loading of SURMOF-2 with metallocene molecules, no remarkable changes of the magnetic properties of the host matrix were observed. However, the magnetic behavior of the guest molecules, as it turned out, is rather different. In the case of nickelocene loading, a polarization effect was found, resulting in ferromagnetic ordering of the guest molecules. However, in the case of manganocene derivatives, the polarization effect is not observed and these molecules remained in their paramagnetic state. The details of these effects are discussed.
Weniger anzeigenHydrogen chloride is produced as a by-product in industrial processes on a million-ton scale. Since HCl is inherently dangerous, its storage and transport are avoided by, e.g., on-site electrolysis providing H2 and Cl2 which usually requires complex cell designs and PFAS-based membranes. Here we report a complementary approach to safely store 0.61 kilogram HCl per kilogram storage material [NEt3Me]Cl forming the bichloride [NEt3Me][Cl(HCl)n]. Although HCl release is possible from this ionic liquid by heat or vacuum, the bichloride can be used directly to produce base chemicals like vinyl chloride. Alternatively, [NEt3Me][Cl(HCl)n] is electrolyzed under anhydrous conditions using a membrane-free cell to generate H2 and the corresponding chlorination agent [NEt3Me][Cl(Cl2)n], enabling the combination of these ionic liquids for the production of base chemicals.
Weniger anzeigenDer Berufsverband Deutscher Psychologinnen und Psychologen (BDP) und die Deutsche Gesellschaft für Psychologie (DGPs) bilden seit 1964 eine Föderation. Als Föderation haben die beiden Vereinigungen die deutsche Psychologie in internationalen Verbänden vertreten und die Reform des Psychologiestudiums sowie die Professionalisierung des Psychologieberufs in Deutschland mitgestaltet. Dabei sind BDP und DGPs selbständige Vereinigungen geblieben, welche auch voneinander abweichende fachpolitische Positionen einnehmen konnten.
Weniger anzeigenChris Hann's essay serves as a valuable intervention against the tendency to normalize primordial ethnonationalism following the full-scale Russian invasion. It is not immune to the common pitfalls and omissions in the writings of many authors whose point of criticism is aimed primarily at the role of Western elites in the conflict within and around Ukraine. But surely, Hann's core argument contains essential truths. Many social scientists have contributed to the construction of a theoretically shallow, methodologically nationalist, and culturally essentializing narrative. It is a telling fact that someone engaging the discussion has to begin with some basic facts of Ukrainian national identity formation, such as its diversity, or has to remind that the interests of the Western ruling classes in the war do not necessarily coincide with the interests of the Ukrainian subaltern classes, or that those are also likely to diverge from the interests and ideologies of their own comprador middle classes calling themselves “civil society.”
Weniger anzeigenBackground
Swelling of the perineal region in male dogs is most commonly caused by a perineal hernia. Clinical signs associated with perineal hernia are constipation, tenesmus or stranguria. This case report documents a rare cause of perineal swelling created by the growth of a malignant tumour leading to urethral obstruction and subsequent stranguria.
Case presentation
An 11-year-old neutered male German Shepherd was presented for swelling in the perineal region and stranguria for three days. Complete blood count and serum biochemistry were unremarkable. Ultrasound revealed a heterogeneous mass in the perineal region. Retrograde urethrography showed a severe narrowing of the urethra caudal to the pelvis. A fine-needle aspirate of the mass was highly suspicious for liposarcoma. Staging was performed by computed tomography (CT) of the thorax and abdomen. Total penile amputation in combination with pubic-ischial pelvic osteotomy, transposition of the remaining urethra through the inguinal canal, V-Y-plasty cranial to the prepuce and preputial urethrostomy were performed to remove the tumour. Histopathology confirmed a well-differentiated liposarcoma with complete histological margins. Six months after the surgery the dog was doing well and there were no signs indicating local tumour recurrence.
Conclusions
Wide surgical excision is generally recommended for soft tissue sarcomas, however this is sometimes not feasible for large tumours. In the case reported here, tumour resection was achieved by a combination of several surgical techniques with a good clinical outcome.
Weniger anzeigenAs the robust maximum likelihood 𝜒2 goodness-of-fit test had been found to yield inflated type-I error rates for certain two-level confirmatory factor analysis (CFA) models, a new correction for the test was implemented in Mplus version 8.7. In this simulation study, we inspected whether the corrected test statistics follow the expected 𝜒2 distributions when applying more complex two-level models for multitrait-multimethod data with varying sample sizes and correlations within trait factors. Investigating rejection rates and probability-probability plots, we found that the new correction markedly and sufficiently reduced previously inflated rejection rates in conditions with within-trait correlations equal to 1, 100 between-level units, and 10 or 20 within-level units. In other conditions, rejection rates were hardly affected or not sufficiently reduced by the new correction. While in most conditions, 2 within-level units did not suffice, 5 within-level units and 250 between-level units were enough to yield correct rejection rates given within-trait correlations did not exceed 0.80. Correlations above 0.80 required larger sample sizes. In planning studies with multilevel CFA models, researchers should be aware that sample size requirements for likelihood-based model fit evaluations can depend on several different factors and might consider conducting Monte Carlo simulations tailored to their specific modeling conditions.
Weniger anzeigen