833 research outputs found
Inhabited Scrolls from the IVth to the VIIth Century A.D. in Asia Minor and the Eastern Provinces of the Byzantine Empire
The "inhabited scroll" is a sinusoidal ornament of vegetal nature - either of vine or acanthus, or even, but rarely an ivy stem, filled with human and animal figures, e.g. vintagers, hares, partridges, and inanimate objects, e.g. baskets and vases. The motif, whose origins have been traced back to Hellenistic ornamental metalwork of the fourth-third century B.C., was popular in the Roman East. The present study confined to inhabited scrolls in architectural sculpture and on mosaic pavements from the fourth to the seventh century in Constantinople and in the eastern provinces of the Byzantine Empire, examines the motif within its immediate architectural, geographical, economic, social and artistic context. It is based on 37 inhabited scrolls in architectural sculpture and 116 on mosaic pavements collected in the course of field-work in Turkey, Cyprus, the Lebanon, Syria, Jordan and Israel, embodied in the catalogue of Vol. II and illustrated in Vols. Ill and IV. Owing to the nature of the material (destroyed, lost, damaged), and in view of its uneven publication, a systematic processing of it has been necessary. It includes the elaboration of a code of types of inhabited scrolls which condenses information and simplifies description. The geographical distribution of inhabited scrolls is examined and the evolution of the motif is traced from late Imperial times, a development illuminated by newly discovered second and third century inhabited scrolls in the Eastern Mediterranean. An attempt is also made to put forward reasons for changes in the distribution patterns from the Roman period when inhabited scrolls predominate in North Africa to the early Byzantine period, when they cluster in the Levant. The cluster in Syro-Cilicia and Palestine is accounted for principally by the booming economic situation of the area in the fifth-sixth century period. The code, moreover, provides a useful means of analysis from which inferences may be drawn particularly in the study of the predominance of some types of inhabited scroll patterns over others and the question of pattern books. Technical aspects of the study, e.g. the analysis of mosaic beds and tesserae stones, size of tesserae and number of tesserae to the dm2, provide information which may be combined with code-type, measurements of pavements, diameter of scrolls, composition, stylistic elements and date to determine "regional groupings" of inhabited scrolls. It is argued that workshops proper can only be determined by a computed cluster analysis combining the various attributes of inhabited scroll pavements cited above. Finally the question of the symbolic significance of the motif is discussed. Like most other motifs from the Graeco-Roman artistic repertory, the inhabited scroll passed into Jewish and Christian art alike, taking a different meaning according to the period, the religion, the building and the onlooker
Oxygen isotope equilibrium in brachiopod shell fibres in the context of biological control
No abstract available
Rydberg-Atom Quantum Simulation and Chern Number Characterization of a Topological Mott Insulator
In this work we consider a system of spinless fermions with nearest and
next-to-nearest neighbor repulsive Hubbard interactions on a honeycomb lattice,
and propose and analyze a realistic scheme for analog quantum simulation of
this model with cold atoms in a two-dimensional hexagonal optical lattice. To
this end, we first derive the zero-temperature phase diagram of the interacting
model within a mean-field theory treatment. We show that besides a
semi-metallic and a charge-density-wave ordered phase, the system exhibits a
quantum anomalous Hall phase, which is generated dynamically, i.e. purely as a
result of the repulsive fermionic interactions and in the absence of any
external gauge fields. We establish the topological nature of this dynamically
created Mott insulating phase by the numerical calculation of a Chern number.
Based on the knowledge of the mean-field phase diagram, we then discuss in
detail how the interacting Hamiltonian can be engineered effectively by
state-of-the-art experimental techniques for laser-dressing of cold fermionic
ground-state atoms with electronically excited Rydberg states that exhibit
strong dipolar interactions.Comment: Revtex4 file, color figures. Final journal version. References
update
Generation and Applications of Human Pluripotent Stem Cells Induced into Neural Lineages and Neural Tissues
Human pluripotent stem cells (hPSCs) represent a new and exciting field in modern medicine, now the focus of many researchers and media outlets. The hype is well-earned because of the potential of stem cells to contribute to disease modeling, drug screening, and even therapeutic approaches. In this review, we focus first on neural differentiation of these cells. In a second part we compare the various cell types available and their advantages for in vitro modeling. Then we provide a “state-of-the-art” report about two major biomedical applications: (1) the drug and toxicity screening and (2) the neural tissue replacement. Finally, we made an overview about current biomedical research using differentiated hPSCs
Detection of Zak phases and topological invariants in a chiral quantum walk of twisted photons
Topological insulators are fascinating states of matter exhibiting protected
edge states and robust quantized features in their bulk. Here, we propose and
validate experimentally a method to detect topological properties in the bulk
of one-dimensional chiral systems. We first introduce the mean chiral
displacement, and we show that it rapidly approaches a multiple of the Zak
phase in the long time limit. Then we measure the Zak phase in a photonic
quantum walk, by direct observation of the mean chiral displacement in its
bulk. Next, we measure the Zak phase in an alternative, inequivalent timeframe,
and combine the two windings to characterize the full phase diagram of this
Floquet system. Finally, we prove the robustness of the measure by introducing
dynamical disorder in the system. This detection method is extremely general,
as it can be applied to all one-dimensional platforms simulating static or
Floquet chiral systems.Comment: 10 pages, 7 color figures (incl. appendices) Close to the published
versio
Quantum anomalous Hall phase in synthetic bilayers via twistronics without a twist
We recently proposed quantum simulators of "twistronic-like" physics based on
ultracold atoms and syntheticdimensions [Phys. Rev. Lett. 125, 030504 (2020)].
Conceptually, the scheme is based on the idea that aphysical monolayer optical
lattice of desired geometry is upgraded to a synthetic bilayer system by
identifyingthe internal states of the trapped atoms with synthetic spatial
dimensions. The couplings between the internalstates, i.e. between sites on the
two layers, can be exquisitely controlled by laser induced Raman transitions.By
spatially modulating the interlayer coupling, Moir\'e-like patterns can be
directly imprinted on the latticewithout the need of a physical twist of the
layers. This scheme leads practically to a uniform pattern across thelattice
with the added advantage of widely tunable interlayer coupling strengths. The
latter feature facilitates theengineering of flat bands at larger "magic"
angles, or more directly, for smaller unit cells than in conventionaltwisted
materials. In this paper we extend these ideas and demonstrate that our system
exhibits topologicalband structures under appropriate conditions. To achieve
non-trivial band topology we consider imanaginarynext-to-nearest neighbor
tunnelings that drive the system into a quantum anomalous Hall phase. In
particular,we focus on three groups of bands, whose their Chern numbers triplet
can be associated to a trivial insulator(0,0,0), a standard non-trivial
(-1,0,1) and a non-standard non-trivial (-1,1,0). We identify regimes of
parameterswhere these three situations occur. We show the presence of an
anomalous Hall phase and the appearance oftopological edge states. Our works
open the path for experiments on topological effects in twistronics without
atwistComment: 11 pages, 10 figure
Cancer Patient Beliefs and Attitudes Regarding Immune Checkpoint Inhibitor Therapy
The development and widespread use of immune checkpoint inhibitors (ICIs) have advanced the field of oncology in a short period of time. Despite this, patient perception regarding this new medication class has not been adequately assessed, which may affect treatment decisions and adherence. The Belief about Medicines Questionnaire (BMQ) is a validated survey composed of 18 questions which analyzes patient’s beliefs about the necessity of prescribed medication and concern about the potential adverse events caused by the medication. General medication overuse and harm are also determined. This is the first study to utilize the BMQ for patients on ICI therapy
Comparison of Eight Methods for the Extraction of Bacillus atrophaeus Spore DNA from Eleven Common Interferents and a Common Swab
Eight DNA extraction products or methods (Applied Biosystems PrepFiler Forensic DNA Extraction Kit; Bio-Rad Instagene Only, Bio-Rad Instagene & Spin Column Purification; EpiCentre MasterPure DNA & RNA Kit; FujiFilm QuickGene Mini80; Idaho Technologies 1-2-3 Q-Flow Kit; MoBio UltraClean Microbial DNA Isolation Kit; Sigma Extract-N-Amp Plant and Seed Kit) were adapted to facilitate extraction of DNA under BSL3 containment conditions. DNA was extracted from 12 common interferents or sample types, spiked with spores of Bacillus atropheaus. Resulting extracts were tested by real-time PCR. No one method was the best, in terms of DNA extraction, across all sample types. Statistical analysis indicated that the PrepFiler method was the best method from six dry powders (baking, biological washing, milk, plain flour, filler and talcum) and one solid (Underarm deodorant), the UltraClean method was the best from four liquids (aftershave, cola, nutrient broth, vinegar), and the MasterPure method was the best from the swab sample type. The best overall method, in terms of DNA extraction, across all sample types evaluated was the UltraClean method
Intron-containing RNA from the HIV-1 provirus activates type I interferon and inflammatory cytokines
HIV-1-infected people who take drugs that suppress viremia to undetectable levels are protected from developing AIDS. Nonetheless, these individuals have chronic inflammation associated with heightened risk of cardiovascular pathology. HIV-1 establishes proviruses in long-lived CD4+ memory T cells, and perhaps other cell types, that preclude elimination of the virus even after years of continuous antiviral therapy. Though the majority of proviruses that persist during antiviral therapy are defective for production of infectious virions, many are expressed, raising the possibility that the HIV-1 provirus or its transcripts contribute to ongoing inflammation. Here we found that the HIV-1 provirus activated innate immune signaling in isolated dendritic cells, macrophages, and CD4+ T cells. Immune activation required transcription from the HIV-1 provirus and expression of CRM1-dependent, Rev-dependent, RRE-containing, unspliced HIV-1 RNA. If rev was provided in trans, all HIV-1 coding sequences were dispensable for activation except those cis-acting sequences required for replication or splicing. These results indicate that the complex, post-transcriptional regulation intrinsic to HIV-1 RNA is detected by the innate immune system as a danger signal, and that drugs which disrupt HIV-1 transcription or HIV-1 RNA metabolism would add qualitative benefit to current antiviral drug regimens
- …