Mixtures of Bosonic and Fermionic Atoms in Optical Lattices

We discuss the theory of mixtures of Bosonic and Fermionic atoms in periodic potentials at zero temperature. We derive a general Bose--Fermi Hubbard Hamiltonian in a one--dimensional optical lattice with a superimposed harmonic trapping potential. We study the conditions for linear stability of the mixture and derive a mean field criterion for the onset of a Bosonic superfluid transition. We investigate the ground state properties of the mixture in the Gutzwiller formulation of mean field theory, and present numerical studies of finite systems. The Bosonic and Fermionic density distributions and the onset of quantum phase transitions to demixing and to a Bosonic Mott--insulator are studied as a function of the lattice potential strength. The existence is predicted of a disordered phase for mixtures loaded in very deep lattices. Such a disordered phase possessing many degenerate or quasi--degenerate ground states is related to a breaking of the mirror symmetry in the lattice.Comment: 11 pages, 8 figures; added discussions; conclusions and references expande

Random Dirac Fermions and Non-Hermitian Quantum Mechanics

We study the influence of a strong imaginary vector potential on the quantum mechanics of particles confined to a two-dimensional plane and propagating in a random impurity potential. We show that the wavefunctions of the non-Hermitian operator can be obtained as the solution to a two-dimensional Dirac equation in the presence of a random gauge field. Consequences for the localization properties and the critical nature of the states are discussed.Comment: 5 pages, Latex, 1 figure, version published in PR

FAIR-compliant clinical, radiomics and DICOM metadata of RIDER, interobserver, Lung1 and head-Neck1 TCIA collections

Purpose: One of the most frequently cited radiomics investigations showed that features automatically extracted from routine clinical images could be used in prognostic modeling. These images have been made publicly accessible via The Cancer Imaging Archive (TCIA). There have been numerous requests for additional explanatory metadata on the following datasets — RIDER, Interobserver, Lung1, and Head–Neck1. To support repeatability, reproducibility, generalizability, and transparency in radiomics research, we publish the subjects’ clinical data, extracted radiomics features, and digital imaging and communications in medicine (DICOM) headers of these four datasets with descriptive metadata, in order to be more compliant with findable, accessible, interoperable, and reusable (FAIR) data management principles. Acquisition and validation methods: Overall survival time intervals were updated using a national citizens registry after internal ethics board approval. Spatial offsets of the primary gross tumor volume (GTV) regions of interest (ROIs) associated with the Lung1 CT series were improved on the TCIA. GTV radiomics features were extracted using the open-source Ontology-Guided Radiomics Analysis Workflow (O-RAW). We reshaped the output of O-RAW to map features and extraction settings to the latest version of Radiomics Ontology, so as to be consistent with the Image Biomarker Standardization Initiative (IBSI). Digital imaging and communications in medicine metadata was extracted using a research version of Semantic DICOM (SOHARD, GmbH, Fuerth; Germany). Subjects’ clinical data were described with metadata using the Radiation Oncology Ontology. All of the above were published in Resource Descriptor Format (RDF), that is, triples. Example SPARQL queries are shared with the reader to use on the online triples archive, which are intended to illustrate how to exploit this data submission. Data format: The accumulated RDF data are publicly accessible through a SPARQL endpoint where the triples are archived. The endpoint is remotely queried through a graph database web application at http://sparql.cancerdata.org. SPARQL queries are intrinsically federated, such that we can efficiently cross-reference clinical, DICOM, and radiomics data within a single query, while being agnostic to the original data format and coding system. The feder

International eDelphi Study to Reach Consensus on the Methotrexate Dosing Regimen in Patients With Psoriasis

Abstract Importance: A clear dosing regimen for methotrexate in psoriasis is lacking, and this might lead to a suboptimal treatment. Because methotrexate is affordable and globally available, a uniform dosing regimen could potentially optimize the treatment of patients with psoriasis worldwide. Objective: To reach international consensus among psoriasis experts on a uniform dosing regimen for treatment with methotrexate in adult and pediatric patients with psoriasis and identify potential future research topics. Design, setting, and participants: Between September 2020 and March 2021, a survey study with a modified eDelphi procedure that was developed and distributed by the Amsterdam University Medical Center and completed by 180 participants worldwide (55 [30.6%] resided in non-Western countries) was conducted in 3 rounds. The proposals on which no consensus was reached were discussed in a conference meeting (June 2021). Participants voted on 21 proposals with a 9-point scale (1-3 disagree, 4-6 neither agree nor disagree, 7-9 agree) and were recruited through the Skin Inflammation and Psoriasis International Network and European Academy of Dermatology and Venereology in June 2020. Apart from being a dermatologist/dermatology resident, there were no specific criteria for participation in the survey. The participants worked mainly at a university hospital (97 [53.9%]) and were experienced in treating patients with psoriasis with methotrexate (163 [91.6%] had more than 10 years of experience). Main outcomes and measures: In a survey with eDelphi procedure, we tried to reach consensus on 21 proposals. Consensus was defined as less than 15% voting disagree (1-3). For the consensus meeting, consensus was defined as less than 30% voting disagree. Results: Of 251 participants, 180 (71.7%) completed all 3 survey rounds, and 58 participants (23.1%) joined the conference meeting. Consensus was achieved on 11 proposals in round 1, 3 proposals in round 2, and 2 proposals in round 3. In the consensus meeting, consensus was achieved on 4 proposals. More research is needed, especially for the proposals on folic acid and the dosing of methotrexate for treating subpopulations such as children and vulnerable patients. Conclusions and relevance: In this eDelphi consensus study, consensus was reached on 20 of 21 proposals involving methotrexate dosing in patients with psoriasis. This consensus may potentially be used to harmonize the treatment with methotrexate in patients with psoriasis