55 research outputs found
Microscopic Theory of the Reentrant IQHE in the First and Second Excited LLs
We present a microscopic theory for the recently observed reentrant integral
quantum Hall effect in the n=1 and n=2 Landau levels. Our energy investigations
indicate an alternating sequence of M-electron-bubble and quantum-liquid ground
states in a certain range of the partial filling factor of the n-th level.
Whereas the quantum-liquid states display the fractional quantum Hall effect,
the bubble phases are insulating, and the Hall resistance is thus quantized at
integral values of the total filling factor.Comment: 4 pages, 4 figures; minor corrections include
Competition between quantum-liquid and electron-solid phases in intermediate Landau levels
On the basis of energy calculations we investigate the competition between
quantum-liquid and electron-solid phases in the Landau levels n=1,2, and 3 as a
function of their partial filling factor. Whereas the quantum-liquid phases are
stable only in the vicinity of quantized values 1/(2s+1) of the partial filling
factor, an electron solid in the form of a triangular lattice of clusters with
a few number of electrons (bubble phase) is energetically favorable between
these fillings. This alternation of electron-solid phases, which are insulating
because they are pinned by the residual impurities in the sample, and quantum
liquids displaying the fractional quantum Hall effect explains a recently
observed reentrance of the integral quantum Hall effect in the Landau levels
n=1 and 2. Around half-filling of the last Landau level, a uni-directional
charge density wave (stripe phase) has a lower energy than the bubble phase.Comment: 12 pages, 9 figures; calculation of exact exchange potential for
n=1,2,3 included, energies of electron-solid phases now calculated with the
help of the exact potential, and discussion of approximation include
Effects of the field modulation on the Hofstadter's spectrum
We study the effect of spatially modulated magnetic fields on the energy
spectrum of a two-dimensional (2D) Bloch electron. Taking into account four
kinds of modulated fields and using the method of direct diagonalization of the
Hamiltonian matrix, we calculate energy spectra with varying system parameters
(i.e., the kind of the modulation, the relative strength of the modulated field
to the uniform background field, and the period of the modulation) to elucidate
that the energy band structure sensitively depends on such parameters:
Inclusion of spatially modulated fields into a uniform field leads occurrence
of gap opening, gap closing, band crossing, and band broadening, resulting
distinctive energy band structure from the Hofstadter's spectrum. We also
discuss the effect of the field modulation on the symmetries appeared in the
Hofstadter's spectrum in detail.Comment: 7 pages (in two-column), 10 figures (including 2 tables
Shape characterization of polymersome morphologies via light scattering techniques
Polymersomes, vesicles self-assembled from amphiphilic block copolymers, are well known for their robustness and for their broad applicability. Generating polymersomes of different shape is a topic of recent attention, specifically in the field of biomedical applications. To obtain information about their exact shape, tomography based on cryo-electron microscopy is usually the most preferred technique. Unfortunately, this technique is rather time consuming and expensive. Here we demonstrate an alternative analytical approach for the characterization of differently shaped polymersomes such as spheres, prolates and discs via the combination of multi-angle light scattering (MALS) and quasi-elastic light scattering (QELS). The use of these coupled techniques allowed for accurate determination of both the radius of gyration (Rg) and the hydrodynamic radius (Rh). This afforded us to determine the shape ratio ρ (Rg/Rh) with which we were able to distinguish between polymersome spheres, discs and rods.</p
Spin-Charge Separation in the Model: Magnetic and Transport Anomalies
A real spin-charge separation scheme is found based on a saddle-point state
of the model. In the one-dimensional (1D) case, such a saddle-point
reproduces the correct asymptotic correlations at the strong-coupling
fixed-point of the model. In the two-dimensional (2D) case, the transverse
gauge field confining spinon and holon is shown to be gapped at {\em finite
doping} so that a spin-charge deconfinement is obtained for its first time in
2D. The gap in the gauge fluctuation disappears at half-filling limit, where a
long-range antiferromagnetic order is recovered at zero temperature and spinons
become confined. The most interesting features of spin dynamics and transport
are exhibited at finite doping where exotic {\em residual} couplings between
spin and charge degrees of freedom lead to systematic anomalies with regard to
a Fermi-liquid system. In spin dynamics, a commensurate antiferromagnetic
fluctuation with a small, doping-dependent energy scale is found, which is
characterized in momentum space by a Gaussian peak at (, ) with
a doping-dependent width (, is the doping
concentration). This commensurate magnetic fluctuation contributes a
non-Korringa behavior for the NMR spin-lattice relaxation rate. There also
exits a characteristic temperature scale below which a pseudogap behavior
appears in the spin dynamics. Furthermore, an incommensurate magnetic
fluctuation is also obtained at a {\em finite} energy regime. In transport, a
strong short-range phase interference leads to an effective holon Lagrangian
which can give rise to a series of interesting phenomena including linear-
resistivity and Hall-angle. We discuss the striking similarities of these
theoretical features with those found in the high- cuprates and give aComment: 70 pages, RevTex, hard copies of 7 figures available upon request;
minor revisions in the text and references have been made; To be published in
July 1 issue of Phys. Rev. B52, (1995
Methods for high-dimensonal analysis of cells dissociated from cyropreserved synovial tissue
Background: Detailed molecular analyses of cells from rheumatoid arthritis (RA) synovium hold promise in identifying cellular phenotypes that drive tissue pathology and joint damage. The Accelerating Medicines Partnership RA/SLE Network aims to deconstruct autoimmune pathology by examining cells within target tissues through multiple high-dimensional assays. Robust standardized protocols need to be developed before cellular phenotypes at a single cell level can be effectively compared across patient samples. Methods: Multiple clinical sites collected cryopreserved synovial tissue fragments from arthroplasty and synovial biopsy in a 10% DMSO solution. Mechanical and enzymatic dissociation parameters were optimized for viable cell extraction and surface protein preservation for cell sorting and mass cytometry, as well as for reproducibility in RNA sequencing (RNA-seq). Cryopreserved synovial samples were collectively analyzed at a central processing site by a custom-designed and validated 35-marker mass cytometry panel. In parallel, each sample was flow sorted into fibroblast, T-cell, B-cell, and macrophage suspensions for bulk population RNA-seq and plate-based single-cell CEL-Seq2 RNA-seq. Results: Upon dissociation, cryopreserved synovial tissue fragments yielded a high frequency of viable cells, comparable to samples undergoing immediate processing. Optimization of synovial tissue dissociation across six clinical collection sites with ~ 30 arthroplasty and ~ 20 biopsy samples yielded a consensus digestion protocol using 100 μg/ml of Liberase™ TL enzyme preparation. This protocol yielded immune and stromal cell lineages with preserved surface markers and minimized variability across replicate RNA-seq transcriptomes. Mass cytometry analysis of cells from cryopreserved synovium distinguished diverse fibroblast phenotypes, distinct populations of memory B cells and antibody-secreting cells, and multiple CD4+ and CD8+ T-cell activation states. Bulk RNA-seq of sorted cell populations demonstrated robust separation of synovial lymphocytes, fibroblasts, and macrophages. Single-cell RNA-seq produced transcriptomes of over 1000 genes/cell, including transcripts encoding characteristic lineage markers identified. Conclusions: We have established a robust protocol to acquire viable cells from cryopreserved synovial tissue with intact transcriptomes and cell surface phenotypes. A centralized pipeline to generate multiple high-dimensional analyses of synovial tissue samples collected across a collaborative network was developed. Integrated analysis of such datasets from large patient cohorts may help define molecular heterogeneity within RA pathology and identify new therapeutic targets and biomarkers
The ARID1B spectrum in 143 patients: from nonsyndromic intellectual disability to Coffin–Siris syndrome
Purpose: Pathogenic variants in ARID1B are one of the most frequent causes of intellectual disability (ID) as determined by large-scale exome sequencing studies. Most studies published thus far describe clinically diagnosed Coffin–Siris patients (ARID1B-CSS) and it is unclear whether these data are representative for patients identified through sequencing of unbiased ID cohorts (ARID1B-ID). We therefore sought to determine genotypic and phenotypic differences between ARID1B-ID and ARID1B-CSS. In parallel, we investigated the effect of different methods of phenotype reporting. Methods: Clinicians entered clinical data in an extensive web-based survey. Results: 79 ARID1B-CSS and 64 ARID1B-ID patients were included. CSS-associated dysmorphic features, such as thick eyebrows, long eyelashes, thick alae nasi, long and/or broad philtrum, small nails and small or absent fifth distal phalanx and hypertrichosis, were observed significantly more often (p < 0.001) in ARID1B-CSS patients. No other significant differences were identified. Conclusion: There are only minor differences between ARID1B-ID and ARID1B-CSS patients. ARID1B-related disorders seem to consist of a spectrum, and patients should be managed similarly. We demonstrated that data collection methods without an explicit option to report the absence of a feature (such as most Human Phenotype Ontology-based methods) tended to underestimate gene-related features
A Novel High-Performance CMOS VCRO Based on Electrically Doped Nanowire FETs in 10 nm Node
In this paper, the idea of electrically doped (ED) Nano-scale TFETs is used to design a non-tunneling n-type NWFET with an additional gate named the side-gate (SG). The work function of SG and the efects of its voltage on the performance of the ED-NWFET device are analyzed. A conventional p-type NWFET and the proposed n-type ED-NWFET are used to design a CMOS inverter, which exhibits considerable dependency on the voltage of the side-gate. Three stages of this inverter are used to design a CMOS voltage-controlled ring oscillator (VCRO), which has a high frequency range of 89.2 to 465 GHz for the side-gate voltage range of 0 to 1 V. Consequently, it has a high frequency tuning range of approximately 136%. The tuning range, phase noise, fgure of merit (FoM) and the fgure of merit with tuning range (FoMT) of the proposed VCRO are superior in comparison with other reported VCROs. The proposed VCRO also has excellent linear frequency-voltage characteristics in the side-gate voltage range of 0.2 to 0.5 V. This linear VCRO exhibits superior performance, including a wide frequency range, compared to other linear VCROs. The results presented in this paper have demonstrated the efcacy of the proposed Nano-scale device engineering-based circuit design technique for applications over a wide frequency range
Supplementary Material for: Plasma Endothelin-1 and Vascular Endothelial Growth Factor Levels and Their Relationship to Hemodynamics in Idiopathic Pulmonary Fibrosis
<b><i>Background:</i></b> Pulmonary hypertension (PH) is associated with a poor prognosis in idiopathic pulmonary fibrosis (IPF). Endothelin-1 (ET-1) and vascular endothelial growth factor (VEGF) are important in both fibrosis and vascular remodeling. <b><i>Objectives:</i></b> We sought to determine the relationship between ET-1 and VEGF levels and hemodynamics in patients with IPF. We hypothesized that higher levels of ET-1 and VEGF would be associated with higher pulmonary artery pressures (PAP) and pulmonary vascular resistance (PVR) in patients with IPF. <b><i>Methods:</i></b> We performed a cross-sectional analysis of 52 adults with IPF enrolled in a prospective cohort with available clinical data, platelet-free plasma, and hemodynamics. ET-1 and VEGF levels were measured via immunoassay. The associations of ET-1 and VEGF with PAP and PVR were examined using generalized additive models adjusted for age, gender, race/ethnicity, and forced vital capacity (% predicted). <b><i>Results:</i></b> Sixteen of 52 (30.8%) had PH (mean PAP ≥25 mm Hg). After multivariable adjustment, higher ET-1 levels were significantly associated with higher systolic (p = 0.01), diastolic (p = 0.02), and mean (p = 0.01) PAP and possibly higher PVR (p = 0.09). There were no significant associations between VEGF levels and hemodynamics. <b><i>Conclusions:</i></b> Higher levels of ET-1 were associated with higher PAP and possibly higher PVR in participants with IPF. In a subgroup of patients, ET-1 may be a contributor to pulmonary vascular disease burden in IPF
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