Search results for "Instability"
showing 10 items of 724 documents
Post-transplant consolidation based on combination of lenalidomide and proteasome inhibitors in multiple myeloma
2021
Multiple myeloma (MM) is a hematological malignancy due to uncontrolled proliferation of neoplastic plasma cells in the bone marrow, associated to chromosomal instability and cytogenetic abnormalities, which could have an impact on prognosis. Response to treatment and survival of newly diagnosed myeloma patients is heterogeneous, with median overall survival ranging from two to more than ten years, due to clinical and biological factors. To warrant long-term control of disease, several strategies have been proposed in the last years, including short-term high-dose of treatment, named as consolidation, before maintenance. This review will discuss the role of consolidation in the current myel…
<i>BRAF</i> Mutation Testing in Lynch Syndrome Diagnostics: Performance and Efficiency According to Patient's Age
2019
Background: BRAF V600E mutations are reportedly associated with sporadic microsatellite-unstable (MSI) colorectal cancer (CRC), while rarely detected in CRCs of Lynch syndrome (LS) patients. Therefore, current international diagnostic guidelines recommend somatic BRAF mutation testing in MLH1-deficient MSI CRC patients to exclude LS. As sporadic BRAF- mutant MSI CRC is a disease of the elderly, while LS-associated CRC usually occurs at younger age, we hypothesized that the efficacy of BRAF testing in LS diagnostics may be age-dependent. Methods: We systematically compared the prevalence of BRAF mutations in LS-associated CRCs and MSI CRCs from population-based cohorts in different age group…
Emergence of extreme events in fiber-based parametric processes driven by a partially incoherent pump wave
2009
Modulation instability (MI) generated by a picosecond coherent pulse has been recently identified as the key element of the generation of optical rogue-waves in supercontinuum-based systems [1]. Similar rare but highly energetic pulse structures can also appear in non-solitonic configurations such as Raman amplifiers driven by a partially incoherent pump wave propagating in fibres with low group velocity dispersion [2]. Therefore, one may wonder whether optical rogue-like event can also occur in MI-based amplifier because both Raman and parametric amplifiers benefit from a quasi-instantaneous gain. We provide here experimental evidence of rare optical events in a parametric amplifier in pre…
Modulational instability in optical fibers with arbitrary higher-order dispersion and delayed Raman response
2006
International audience; We analyse modulational instability (MI) of electromagnetic waves in a large variety of optical fibers having different refractive-index profiles. For the normal-, anomalous-, and zero-dispersion regimes of the wave propagation, we show that whenever the second-order dispersion competes with higher-order dispersion (HOD), propagation of plane waves leads to a rich variety of dynamical behaviors. Most of the richness comes from the existence of critical behaviors, which include situations in which the HOD suppresses MI in the anomalous dispersion regime, and other situations in which the HOD acts in the opposite way by inducing non-conventional MI processes in the nor…
Generalized modulational instability in multimode fibers: Wideband multimode parametric amplification
2015
In this paper intermodal modulational instability (IM-MI) is analyzed in a multimode fiber where several spatial and polarization modes propagate. The coupled nonlinear Schr\"odinger equations describing the modal evolution in the fiber are linearized and reduced to an eigenvalue problem. As a result, the amplification of each mode can be described by means of the eigenvalues and eigenvectors of a matrix that stores the information about the dispersion properties of the modes and the modal power distribution of the pump. Some useful analytical formulas are also provided that estimate the modal amplification as function of the system parameters. Finally, the impact of third-order dispersion …
Broadband Tuning of Polarization Modulation Instability in Microstructured Optical Fiber through Thermal Heating
2020
Broadband tuning of polarization modulation instability in microstructured optical fibers is reported. Tunability is achieved by simultaneous birefringence-dispersion changes through thermal heating. 906 cm-1 frequency tunability range is attained.
Broadband tuning of polarization modulation instability in microstructured optical fibers
2020
The wideband tuning of strong bands generated through polarization modulation instability (PMI) in microstructured optical fibers (MOFs) is reported. Tunability is achieved by exploiting the dependence of the phase-matching condition on the fiber’s chromatic dispersion and birefringence, which is particularly sensitive when the fiber is pumped near the zero-dispersion wavelength. MOFs designed to accomplish PMI phase-matching when they are infiltrated with ethanol and pumped at 1064 nm were designed and fabricated. Taking advantage of the large thermo-optic coefficient of ethanol, both chromatic dispersion and birefringence were varied through temperature. Wavelength shifts from 937 nm to 8…
Shallow water rogue wavetrains in nonlinear optical fibers
2013
International audience; In addition to deep-water rogue waves which develop from the modulation instability of an optical CW, wave propagation in optical fibers may also produce shallow water rogue waves. These extreme wave events are generated in the modulationally stable normal dispersion regime. A suitable phase or frequency modulation of a CW laser leads to chirp-free and flat-top pulses or flaticons which exhibit a stable self-similar evolution. Upon collision, flaticons at different carrier frequencies, which may also occur in wavelength division multiplexed transmission systems, merge into a single, high-intensity, temporally and spatially localized rogue pulse.
Design of a continuously tunable delay line using vectorial modulational instability and chromatic dispersion in optical fibers
2009
International audience; We design an all-optical tunable delay line based on both dispersive and wavelength conversion stages involving modulational instability of a two-frequency pump field propagating in a highly birefringent fiber. More precisely, we numerically show that, by varying the frequency separation between the two orthogonally polarized pump waves, we achieve a controllable and continuous delay of hundreds of picoseconds for signal pulse durations from picoseconds to nanoseconds, without pulse distortion and with only small peak power fluctuations. The proposed method does not require any tunable bandpass filter and can be applied to delay digital data streams at tens of Gbit/s…
ultra-short pulse propagation at 160-Gb/s in dispersion managed optical fiber lines
2004
This thesis presents a study on ultra-short pulse propagation at 160-Gb/s in dispersion managed optical fiber lines. In a first part, we describe the experimental design of a SHG-FROG setup able to characterize high repetition rate pulse trains. Secondly, we demonstrate the efficiency of multiple four wave mixing phenomenon for the generation of a 160-GHz pulse train through the compression of a sinusoidal beat-signal. Then, in order to compare the experimental and theoretical results, we present the development of an optical fiber characterization benchtop based on modulational instability. In the last part of this thesis, we built and compare several recirculating loop setups. On the one …