116 research outputs found
External modulation method for generating accurate linear optical FMCW
Frequency modulation continuous wave (FMCW) lasers are key components in modern optical imaging. However, current intracavity modulation lasers do not exhibit low-frequency jitter rate and high linearity due to the inherent relaxation oscillations. Although this may be compensated in a direct modulation laser diode using an optoelectronic feedback loop, the available sweep speed is moderately small. In this letter, a special external modulation method is developed to improve the performance of FMCW. Since only the first sideband optical field is used during the entire generation process, phase noise is kept to a minimum and is also independent of the sweep speed. We demonstrate that the linearity and jitter rates do not deteriorate appreciably when the sweep speed is changed over three orders of magnitude, even up to the highest sweep speed of 2.5 GHz/ μs
Wavelength conversion through plasmon-coupled surface states
Surface states generally degrade semiconductor device performance by raising
the charge injection barrier height, introducing localized trap states,
inducing surface leakage current, and altering the electric potential.
Therefore, there has been an endless effort to use various surface passivation
treatments to suppress the undesirable impacts of the surface states. We show
that the giant built-in electric field created by the surface states can be
harnessed to enable passive wavelength conversion without utilizing any
nonlinear optical phenomena. Photo-excited surface plasmons are coupled to the
surface states to generate an electron gas, which is routed to a nanoantenna
array through the giant electric field created by the surface states. The
induced current on the nanoantennas, which contains mixing product of different
optical frequency components, generates radiation at the beat frequencies of
the incident photons. We utilize the unprecedented functionalities of
plasmon-coupled surface states to demonstrate passive wavelength conversion of
nanojoule optical pulses at a 1550 nm center wavelength to terahertz regime
with record-high efficiencies that exceed nonlinear optical methods by 4-orders
of magnitude. The presented scheme can be used for optical wavelength
conversion to different parts of the electromagnetic spectrum ranging from
microwave to infrared regimes by using appropriate optical beat frequencies.Comment: Manuscript: 8 pages, 4 figures Supplementary materials: 21 pages, 11
figure
Iatrogenic hemobilia: imaging features and management with transcatheter arterial embolization in 30 patients
PURPOSE:We aimed to evaluate the imaging features of computed tomography (CT) and angiography and the efficacy of transcatheter arterial embolization (TAE) in patients with hemobilia of different iatrogenic causes.METHODS:Thirty patients with hemobilia were divided into two groups according to their iatrogenic causes, i.e., group 1, 11 patients (36.7%) with transhepatic intervention and group 2, 19 patients (63.3%) with surgical procedures in the hilar area. Seventeen patients (56.7%) underwent abdominal contrast-enhanced CT before selective angiography. Polyvinyl alcohol particles, gelatin sponges, and coils were used for TAE. Data from the two groups were compared using Fisher’s exact test and the Mann-Whitney U test.RESULTS:Contrast-enhanced CT showed a hematoma, extravasation of contrast material, and pseudoaneurysm. The bleeding source was determined by angiographic features in all patients, which were not significantly different between the two groups (P = 0.127), and pseudoaneurysm was the most common. The embolic material and number of coils used for TAE were significantly different between the two groups (P < 0.001), but the embolization was technically successful in all patients. The clinical success rate of the first embolization was 100% in group 1 vs. 84.2% in group 2. The overall clinical success rate of TAE was 100% in all patients. The complication rate was 63.6% in group 1 vs. 68.4% in group 2 (P = 1.000).CONCLUSION:CT was useful in diagnosing hemobilia, and angiograms enabled determination of the bleeding source. Pseudoaneurysm was one of the most common angiographic features. TAE was successfully performed with different embolic materials on the basis of the iatrogenic cause and bleeding location
Identification of core cuprotosis-correlated biomarkers in abdominal aortic aneurysm immune microenvironment based on bioinformatics
BackgroundThe occurrence of abdominal aortic aneurysms (AAAs) is related to the disorder of immune microenvironment. Cuprotosis was reported to influence the immune microenvironment. The objective of this study is to identify cuprotosis-related genes involved in the pathogenesis and progression of AAA.MethodsDifferentially expressed lncRNAs (DElncRNAs) and mRNAs (DEmRNAs) in mouse were identified following AAA through high-throughput RNA sequencing. The enrichment analyses of pathway were selected through Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG). The validation of cuprotosis-related genes was conducted through immunofluorescence and western blot analyses.ResultsTotally, 27616 lncRNAs and 2189 mRNAs were observed to be differentially expressed (|Fold Change| ≥ 2 and q< 0.05) after AAA, including 10424 up-regulated and 17192 down-regulated lncRNAs, 1904 up-regulated and 285 down-regulated mRNAs. Gene ontology and KEGG pathway analysis showed that the DElncRNAs and DEmRNAs were implicated in many different biological processes and pathways. Furthermore, Cuprotosis-related genes (NLRP3, FDX1) were upregulated in the AAA samples compared with the normal one.ConclusionCuprotosis-related genes (NLRP3,FDX1) involved in AAA immune environment might be critical for providing new insight into identification of potential targets for AAA therapy
Non-Fermi liquid behavior in a correlated flatband pyrochlore lattice
Electronic correlation effects are manifested in quantum materials when
either the onsite Coulomb repulsion is large or the electron kinetic energy is
small. The former is the dominant effect in the cuprate superconductors or
heavy fermion systems while the latter in twisted bilayer graphene or
geometrically frustrated metals. However, the simultaneous cooperation of both
effects in the same quantum material--the design principle to produce a
correlated topological flat bands pinned at the Fermi level--remains rare.
Here, using angle-resolved photoemission spectroscopy, we report the
observation of a flat band at the Fermi level in a 3 pyrochlore metal
CuVS. From a combination of first-principles calculations and
slave-spin calculations, we understand the origin of this band to be a
destructive quantum-interference effect associated with the V pyrochlore
sublattice and further renormalization to the Fermi level by electron
interactions in the partially filled V orbitals. As a result, we find
transport behavior that indicates a deviation from Fermi-liquid behavior as
well as a large Sommerfeld coefficient. Our work demonstrates the pathway into
correlated topology by constructing and pinning correlated flat bands near the
Fermi level out of a pure -electron system by the combined cooperation of
local Coulomb interactions and geometric frustration in a pyrochlore lattice
system.Comment: 23 pages, 4 figures, to appear in Nature Physic
- …