452 research outputs found
Antiphosphatidylserine antibody as a cause of multiple dural venous sinus thromboses and ST-elevation myocardial infarction
Objective: Rare disease Background: Antiphospholipid syndrome (APS) is an autoimmune disease characterized by antibodies directed against phos-pholipids on plasma membranes. Through unclear mechanisms, APS confers hypercoagulability. APS may cause recurrent thromboses in the arterial and venous vasculature. We report a case of primary APS resulting in cerebral venous thrombosis and ST-elevation myocardial infarction (STEMI) for which only antiphosphatidylserine (aPS) IgM antibody was positive after extensive investigation. Case Report: A 48-year-old male was admitted after a witnessed generalized seizure with subsequent confusion. Imaging demonstrated thrombosis of multiple central nervous system (CNS) sinuses, including the superior sagittal sinus and bilateral transverse sinuses. The patient was heparinized with aggressive hydration, which proved inadequate, prompting endovascular thrombectomy. Three months later, despite anticoagulation therapy, the patient developed a STEMI when International Normalized Ratio (INR) was 1.8. Echocardiogram (ECHO) and PAN CT scan were normal. Initial coagulation studies demonstrated normal anticardiolipin antibody, prothrombin time, partial thromboplastin time, and platelet count. Outpatient coagulation studies revealed normal an-tithrombin III, protein C/S, hemoglobin electrophoresis, homocysteine, anti-b2 glycoprotein 1 antibodies, and D-Dimer. Factor V Leiden, JAK 2 mutation, prothrombin gene mutation, and tests for paroxysmal nocturnal he-moglobinuria (PNH) were negative. A positive phosphatidylserine IgM was detected. The patient was continued on warfarin (10 mg daily) with a target INR of 3.0–3.5 and clopidogrel (75 mg daily). Conclusions: Despite extensive investigation, this patient only showed evidence of elevated aPS IgM antibodies, likely contributing to his CNS venous sinus thromboses and STEMI. It is important to screen for antiphosphatidylserine antibodies in cases of unprovoked thrombosis when standard thrombophilia analysis is unrevealing. This will assist in identifying pathogenicity and help prevent recurrence of subsequent thromboses. © Am J Case Rep, 2018
Quantum Uncertainty in the Beam Width of Spatial Optical Modes
We theoretically investigate the quantum uncertainty in the beam width of
transverse optical modes and, for this purpose, define a corresponding quantum
operator. Single mode states are studied as well as multimode states with small
quantum noise. General relations are derived, and specific examples of
different modes and quantum states are examined. For the multimode case, we
show that the quantum uncertainty in the beam width can be completely
attributed to the amplitude quadrature uncertainty of one specific mode, which
is uniquely determined by the field under investigation. This discovery
provides us with a strategy for the reduction of the beam width noise by an
appropriate choice of the quantum state
The photonic wheel: demonstration of a state of light with purely transverse angular momentum
The concept of angular momentum is ubiquitous to many areas of physics. In
classical mechanics, a system may possess an angular momentum which can be
either transverse (e.g., in a spinning wheel) or longitudinal (e.g., for a
fluidic vortex) to the direction of motion. Photons, however, are well-known to
exhibit intrinsic angular momentum which is longitudinal only: the spin angular
momentum defining the beam polarization and the orbital angular momentum
associated with a spiraling phase front. Here we show that it is possible to
generate a novel state of light that contains purely transverse angular
momentum, the analogue of a spinning mechanical wheel. We use an optical
nano-probing technique to experimentally demonstrate its occurrence in our
setup. Such a state of light can provide additional rotational degree of
freedom in optical tweezers and optical manipulation.Comment: 15 pages including SO
The polarization properties of a tilted polarizer
Polarizers are key components in optical science and technology. Thus,
understanding the action of a polarizer beyond oversimplifying approximations
is crucial. In this work, we study the interaction of a polarizing interface
with an obliquely incident wave experimentally. To this end, a set of Mueller
matrices is acquired employing a novel procedure robust against experimental
imperfections. We connect our observation to a geometric model, useful to
predict the effect of polarizers on complex light fields.Comment: 11 pages, 5 figure
Classically entangled optical beams for high-speed kinematic sensing
Tracking the kinematics of fast-moving objects is an important diagnostic
tool for science and engineering. Existing optical methods include high-speed
CCD/CMOS imaging, streak cameras, lidar, serial time-encoded imaging and
sequentially timed all-optical mapping. Here, we demonstrate an entirely new
approach to positional and directional sensing based on the concept of
classical entanglement in vector beams of light. The measurement principle
relies on the intrinsic correlations existing in such beams between transverse
spatial modes and polarization. The latter can be determined from intensity
measurements with only a few fast photodiodes, greatly outperforming the
bandwidth of current CCD/CMOS devices. In this way, our setup enables
two-dimensional real-time sensing with temporal resolution in the GHz range. We
expect the concept to open up new directions in photonics-based metrology and
sensing.Comment: v2 includes the real-time measurement from the published version.
Reference [29] added. Minor experimental details added on page
Transcriptional read-through of the long non-coding RNA SVALKA governs plant cold acclimation
The function of most lncRNA is unknown. Here, the authors show that transcriptional read-through at the Arabidopsis SVALKA locus produces a cryptic lncRNA that overlaps with the neighboring cold-responsive CBF1 gene and limits CBF1 expression via an RNA polymerase II collision-based mechanism
Free-space propagation of high dimensional structured optical fields in an urban environment
Spatially structured optical fields have been used to enhance the functionality of a wide variety of systems that use
light for sensing or information transfer. As higher-dimensional modes become a solution of choice in optical
systems, it is important to develop channel models that suitably predict the effect of atmospheric turbulence on
these modes. We investigate the propagation of a set of orthogonal spatial modes across a free-space channel
between two buildings separated by 1.6 km. Given the circular geometry of a common optical lens, the orthogonal
mode set we choose to implement is that described by the Laguerre-Gaussian (LG) field equations. Our study focuses
on the preservation of phase purity, which is vital for spatial multiplexing and any system requiring full quantumstate
tomography. We present experimental data for the modal degradation in a real urban environment and draw a
comparison to recognized theoretical predictions of the link. Our findings indicate that adaptations to channel
models are required to simulate the effects of atmospheric turbulence placed on high-dimensional structured
modes that propagate over a long distance. Our study indicates that with mitigation of vortex splitting, potentially
through precorrection techniques, one could overcome the challenges in a real point-to-point free-space channel in
an urban environment
Multiband k p model and fitting scheme for ab initio-based electronic structure parameters for wurtzite GaAs
We develop a 16-band k · p model for the description of wurtzite GaAs, together with a novel scheme to determine electronic structure parameters for multiband k · p models. Our approach uses low-discrepancy sequences to fit k · p band structures beyond the eight-band scheme to most recent ab initio data, obtained within the framework for hybrid-functional density functional theory with a screened-exchange hybrid functional. We report structural parameters, elastic constants, band structures along high-symmetry lines, and deformation potentials at the Γ point. Based on this, we compute the bulk electronic properties (Γ point energies, effective masses, Luttinger-like parameters, and optical matrix parameters) for a ten-band and a sixteen-band k · p model for wurtzite GaAs. Our fitting scheme can assign priorities to both selected bands and k points that are of particular interest for specific applications. Finally, ellipticity conditions can be taken into account within our fitting scheme in order to make the resulting parameter sets robust against spurious solutions
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Multiband k p model and fitting scheme for ab initio-based electronic structure parameters for wurtzite GaAs
We develop a 16-band k · p model for the description of wurtzite GaAs, together with a novel scheme to determine electronic structure parameters for multiband k · p models. Our approach uses low-discrepancy sequences to fit k · p band structures beyond the eight-band scheme to most recent ab initio data, obtained within the framework for hybrid-functional density functional theory with a screened-exchange hybrid functional. We report structural parameters, elastic constants, band structures along high-symmetry lines, and deformation potentials at the Γ point. Based on this, we compute the bulk electronic properties (Γ point energies, effective masses, Luttinger-like parameters, and optical matrix parameters) for a ten-band and a sixteen-band k · p model for wurtzite GaAs. Our fitting scheme can assign priorities to both selected bands and k points that are of particular interest for specific applications. Finally, ellipticity conditions can be taken into account within our fitting scheme in order to make the resulting parameter sets robust against spurious solutions
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