3,478 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 3.0β3.5 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. Β© Am J Case Rep, 2018
Entanglement of mechanical oscillators coupled to a non-equilibrium environment
Recent experiments aim at cooling nanomechanical resonators to the ground
state by coupling them to non-equilibrium environments in order to observe
quantum effects such as entanglement. This raises the general question of how
such environments affect entanglement. Here we show that there is an optimal
dissipation strength for which the entanglement between two coupled oscillators
is maximized. Our results are established with the help of a general framework
of exact quantum Langevin equations valid for arbitrary bath spectra, in and
out of equilibrium. We point out why the commonly employed Lindblad approach
fails to give even a qualitatively correct picture
Brillouin Cooling
We analyze how to exploit Brillouin scattering for the purpose of cooling
opto-mechanical devices and present a quantum-mechanical theory for Brillouin
cooling. Our analysis shows that significant cooling ratios can be obtained
with standard experimental parameters. A further improvement of cooling
efficiency is possible by increasing the dissipation of the optical anti-Stokes
resonance.Comment: 4 pages 3 figure
Free-space quantum links under diverse weather conditions
Free-space optical communication links are promising channels for
establishing secure quantum communication. Here we study the transmission of
nonclassical light through a turbulent atmospheric link under diverse weather
conditions, including rain or haze. To include these effects, the theory of
light transmission through atmospheric links in the elliptic-beam approximation
presented by Vasylyev et al. [D. Vasylyev et al., Phys. Rev. Lett. 117, 090501
(2016); arXiv:1604.01373] is further generalized.It is demonstrated, with good
agreement between theory and experiment, that low-intensity rain merely
contributes additional deterministic losses, whereas haze also introduces
additional beam deformations of the transmitted light. Based on these results,
we study theoretically the transmission of quadrature squeezing and Gaussian
entanglement under these weather conditions.Comment: 14 pages, 8 figure
Π£ΡΠ΅Π½ΠΎΠΌΡ ΡΠ΅ΠΊΡΠ΅ΡΠ°ΡΡ Π Π΅Π΄ΠΊΠΎΠ»Π»Π΅Π³ΠΈΠΈ ΠΆΡΡΠ½Π°Π»Π° "ΠΠ·Π²Π΅ΡΡΠΈΡ Π’ΠΠ£" Π΄ΠΎΡΠ΅Π½ΡΡ Π‘. Π. ΠΠΎΠ³ΠΈΠ»ΡΠ½ΠΈΡΠΊΠΎΠΌΡ - 60 Π»Π΅Ρ
ΠΠΏΠΈΡΠ°Π½ ΠΆΠΈΠ·Π½Π΅Π½Π½ΡΠΉ ΠΏΡΡΡ, Π»ΠΈΡΠ½ΡΠ΅ ΠΊΠ°ΡΠ΅ΡΡΠ²Π°, ΡΡΠ΅Π±Π½Π°Ρ ΠΈ Π½Π°ΡΡΠ½Π°Ρ Π΄Π΅ΡΡΠ΅Π»ΡΠ½ΠΎΡΡΡ ΠΈ Π΄ΠΎΡΡΠΈΠΆΠ΅Π½ΠΈΡ ΡΡΠ΅Π½ΠΎΠ³ΠΎ ΡΠ΅ΠΊΡΠ΅ΡΠ°ΡΡ Π Π΅Π΄ΠΊΠΎΠ»Π»Π΅Π³ΠΈΠΈ ΠΆΡΡΠ½Π°Π»Π° "ΠΠ·Π²Π΅ΡΡΠΈΡ Π’ΠΠ£", ΠΊΠ°Π½Π΄ΠΈΠ΄Π°ΡΠ° ΡΠΈΠ·ΠΈΠΊΠΎ-ΠΌΠ°ΡΠ΅ΠΌΠ°ΡΠΈΡΠ΅ΡΠΊΠΈΡ
Π½Π°ΡΠΊ, Π΄ΠΎΡΠ΅Π½ΡΠ° Π’ΠΎΠΌΡΠΊΠΎΠ³ΠΎ ΠΏΠΎΠ»ΠΈΡΠ΅Ρ
Π½ΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΡΠ½ΠΈΠ²Π΅ΡΡΠΈΡΠ΅ΡΠ° Π‘Π΅ΡΠ³Π΅Ρ ΠΠΎΡΠΈΡΠΎΠ²ΠΈΡΠ° ΠΠΎΠ³ΠΈΠ»ΡΠ½ΠΈΡΠΊΠΎΠ³
ΠΠ»ΠΈΡΠ½ΠΈΠ΅ Π»ΡΡΠΈΡΡΠΎΠ³ΠΎ ΡΠ΅ΠΏΠ»ΠΎΠΏΠ΅ΡΠ΅Π½ΠΎΡΠ° Π½Π° ΠΌΠΈΠ½ΠΈΠΌΠ°Π»ΡΠ½ΡΡ ΡΠ½Π΅ΡΠ³ΠΈΡ ΠΈΡΠΊΡΠΎΠ²ΠΎΠ³ΠΎ Π·Π°ΠΆΠΈΠ³Π°Π½ΠΈΡ Π²Π·Π²Π΅ΡΠΈ Π½Π°Π½ΠΎΡΠ°Π·ΠΌΠ΅ΡΠ½ΠΎΠΉ ΡΠ³ΠΎΠ»ΡΠ½ΠΎΠΉ ΠΏΡΠ»ΠΈ
Theory of ground state cooling of a mechanical oscillator using dynamical back-action
A quantum theory of cooling of a mechanical oscillator by radiation
pressure-induced dynamical back-action is developed, which is analogous to
sideband cooling of trapped ions. We find that final occupancies well below
unity can be attained when the mechanical oscillation frequency is larger than
the cavity linewidth. It is shown that the final average occupancy can be
retrieved directly from the optical output spectrum.Comment: 5 pages, 2 figure
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
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