452 research outputs found
Coherence and synchronization in diode-laser arrays with delayed global coupling
The dynamics of a semiconductor-laser array whose individual elements are
coupled in a global way through an external mirror is numerically analysed. A
coherent in-phase solution is seen to be preferred by the system at
intermediate values of the feedback coupling strength. At low values of this
parameter, a strong amplification of the spontaneous emission noise is
observed. A tendency towards chaos synchronization is also observed at large
values of the feedback strength.Comment: 8 pages, LaTeX, 6 PS figures, to appear in International Journal of
Bifurcation and Chao
A novel FAS mutation with variable expressivity in a family with unicentric and idiopathic multicentric Castleman disease
Use of aequorin-based indicators for monitoring Ca2+ in acidic organelles
Over the last years, there is accumulating evidence that acidic organelles can accumulate and release Ca2+ upon cell activation. Hence, reliable recording of Ca2+ dynamics in these compartments is essential for understanding the physiopathological aspects of acidic organelles. Genetically encoded Ca2+ indicators (GECIs) are valuable tools to monitor Ca2+ in specific locations, although their use in acidic compartments is challenging due to the pH sensitivity of most available fluorescent GECIs. By contrast, bioluminescent GECIs have a combination of features (marginal pH sensitivity, low background, no phototoxicity, no photobleaching, high dynamic range and tunable affinity) that render them advantageous to achieve an enhanced signal-to-noise ratio in acidic compartments. This article reviews the use of bioluminescent aequorin-based GECIs targeted to acidic compartments. A need for more measurements in highly acidic compartments is identified
Molecular gyroscopes and biological effects of weak ELF magnetic fields
Extremely-low-frequency magnetic fields are known to affect biological
systems. In many cases, biological effects display `windows' in biologically
effective parameters of the magnetic fields: most dramatic is the fact that
relatively intense magnetic fields sometimes do not cause appreciable effect,
while smaller fields of the order of 10--100 T do. Linear resonant
physical processes do not explain frequency windows in this case. Amplitude
window phenomena suggest a nonlinear physical mechanism. Such a nonlinear
mechanism has been proposed recently to explain those `windows'. It considers
quantum-interference effects on protein-bound substrate ions. Magnetic fields
cause an interference of ion quantum states and change the probability of
ion-protein dissociation. This ion-interference mechanism predicts specific
magnetic-field frequency and amplitude windows within which biological effects
occur. It agrees with a lot of experiments. However, according to the
mechanism, the lifetime of ion quantum states within a protein
cavity should be of unrealistic value, more than 0.01 s for frequency band
10--100 Hz. In this paper, a biophysical mechanism has been proposed that (i)
retains the attractive features of the ion interference mechanism and (ii) uses
the principles of gyroscopic motion and removes the necessity to postulate
large lifetimes. The mechanism considers dynamics of the density matrix of the
molecular groups, which are attached to the walls of protein cavities by two
covalent bonds, i.e., molecular gyroscopes. Numerical computations have shown
almost free rotations of the molecular gyros. The relaxation time due to van
der Waals forces was about 0.01 s for the cavity size of 28 angstr\"{o}ms.Comment: 10 pages, 7 figure
Spatial Division Multiplexed Microwave Signal processing by selective grating inscription in homogeneous multicore fibers
[EN] The use of Spatial Division Multiplexing for Microwave Photonics signal processing is proposed and experimentally demonstrated, for the first time to our knowledge, based on the selective inscription of Bragg gratings in homogeneous multicore fibers. The fabricated devices behave as sampled true time delay elements for radiofrequency signals offering a wide range of operation possibilities within the same optical fiber. The key to processing flexibility comes from the implementation of novel multicavity configurations by inscribing a variety of different fiber Bragg gratings along the different cores of a 7-core fiber. This entails the development of the first fabrication method to inscribe high-quality gratings characterized by arbitrary frequency spectra and located in arbitrary longitudinal positions along the individual cores of a multicore fiber. Our work opens the way towards the development of unique compact fiber-based solutions that enable the implementation of a wide variety of 2D (spatial and wavelength diversity) signal processing functionalities that will be key in future fiber-wireless communications scenarios. We envisage that Microwave Photonics systems and networks will benefit from this technology in terms of compactness, operation versatility and performance stability.We thank Prof. Jose Capmany for the thoughtful discussions and recommendations that greatly contribute to this work. This research was supported by the Spanish MINECO Projects TEC2014-60378-C2-1-R and TEC2015-62520-ERC, the Valencian Research Excellency Award Program GVA PROMETEO 2013/012, the Spanish MECD FPU Scholarship (FPU13/04675) for J. Hervas, and the Spanish MINECO Ramon y Cajal Program (RYC-2014-16247) for I. Gasulla.Gasulla Mestre, I.; Barrera Vilar, D.; HervĂĄs-Peralta, J.; Sales Maicas, S. (2017). Spatial Division Multiplexed Microwave Signal processing by selective grating inscription in homogeneous multicore fibers. Scientific Reports. 7(41727):1-10. https://doi.org/10.1038/srep41727S110741727Samsung Electronics Co, â5G Visionâ, available at http://www.samsung.com/global/business-images/insights/2015/Samsung-5G-Vision-0.pdf (2015).Technology Focus on Microwave Photonics. Nat. Photonics 5, 723 (2011).J. Capmany, J. Mora, I. Gasulla, J. Sancho, J. Lloret & S. Sales . Microwave photonic signal processing. IEEE J. Lightw. Technol. 31, 571â586 (2013).Y. Long & J. Wang . Ultra-high peak rejection notch microwave photonic filter using a single silicon microring resonator. Opt. Express 23, 17739â17750 (2015).Y. Long & J. Wang . All-optical tuning of a nonlinear silicon microring assisted microwave photonic filter: theory and experiment. Opt. Express 23, 17758â17771 (2015).Y. Long, L. Zhou & J. Wang . Photonic-assisted microwave signal multiplication and modulation using a silicon MachâZehnder modulator. Sci. Reports 6, 20215 (2016).J. Sancho, J. Bourderionnet, J. Lloret, S. CombriĂ©, I. Gasulla, S. Xavier, S. Sales, P. Colman, G. Lehoucq, D. Dolfi, J. Capmany & A. De Rossi . Integrable microwave filter based on a photonic crystal delay line. Nat. Commun. 3, 1075 (2012).F. Ohman, K. Yvind & J. MĂžrk . Slow Light in a Semiconductor Waveguide for True-Time Delay Applications in Microwave Photonics. IEEE Photon. Technol. Lett. 19, 1145â1157 (2007).P. A. Morton & J. B. Khurgin. Microwave photonic delay line with separate tuning of the optical carrier. IEEE Photon. Technol. Lett. 21, 1686â1688 (2009).D. Marpaung, C. Roeloffzen, R. Heideman, A. Leinse, S. Sales & J. Capmany . Integrated microwave photonics. Lasers Photon. Rev. 7, 506â538 (2013).I. Gasulla & J. Capmany . Microwave photonics applications of multicore fibers. Photonics J. 4, 877â888 (2012).S. Garcia & I. Gasulla . Design of Heterogeneous Multicore fibers as sampled True Time Delay Lines. Opt. Lett. 40, 621â624 (2015).F. Zeng & J. Yao . All-optical microwave filters using uniform fiber Bragg gratings with identical reflectivities. IEEE J. Lightw. Technol. 23, 1410 (2005).C. Wang & J. Yao . Fiber Bragg gratings for microwave photonics subsystems. Opt. Express 21, 22868â22884 (2013).I. Gasulla, D. Barrera & S. Sales . Microwave photonic devices based on multicore fibers. 16th International Conference on Transparent Optical Networks (ICTON), Graz, Austria, 2014.I. Gasulla, D. Barrera, J. HervĂĄs, S. GarcĂa & S. Sales . Multi-cavity Microwave Photonics devices built upon multicore fibres. 18th International Conference on Transparent Optical Networks (ICTON), Trento (Italy), pp. 1â4, 2016.K. O. Hill & G. Meltz . Fiber Bragg grating technology fundamentals and overview. IEEE J. Lightw. Technol. 15, 1263â1276 (1997).T. Erdogan . Fiber grating spectra. IEEE J. Lightw. Technol. 15, 1277â1294 (1997).D. Barrera, I. Gasulla & S. Sales . Multipoint two-dimensional curvature optical fiber sensor based on a non-twisted homogeneous four-core fiber. IEEE J. Lightw. Technol. 33, 2445â2450 (2015).T. Birks, B. Mangan, A. Diez, J. Cruz, S. Leon-Saval, J. Bland-Hawthorn & D. Murphy . Multicore optical fibres for astrophotonics. In CLEO/Europe and EQEC 2011 Conference Digest, OSA Technical Digest (CD)d (Optical Society of America, 2011), paper JSIII2_1.C. Wang, Z. Yan, Q. Sun, Z. Sun, C. Mou, J. Zhang, A. Badmos & L. Zhang . Fibre Bragg gratings fabrication in four core fibres. Proc. SPIE 9886, Micro-Structured and Specialty Optical Fibres IV, 98860H (2016).M. J. Cole, W. H. Loh, R. I. Laming, M. N. Zervas & S. Barcelos . Moving fibre/phase mask-scanning beam technique for enhanced flexibility in producing fibre gratings with uniform phase mask. Electron. Lett. 31, 1488â1490 (1995).M. Gallagher & U. Ăsterberg . Time resolved 3.10 eV luminescence in germanium-doped silica glass. Appl. Phys. Lett. 63, 2987â2988 (1993).T. Komukai & M. Nakazawa . Fabrication of high-quality long fiber Bragg grating by monitoring 3.1 eV radiation (400 nm) from GeO defects. IEEE Photon. Tech. Lett. 8, 1495â1497 (1996).R. R. Thomson, H. T. Bookey, N. D. Psaila, A. Fender, S. Campbell, W. N. MacPherson, J. S. Barton, D. T. Reid & A. K. Kar . Ultrafast-laser inscription of a three dimensional fan-out device for multicore fiber coupling applications. Opt. Express 15, 11691â11697 (2007)
Differential role of MLKL in alcohol-associated and non-alcohol-associated fatty liver diseases in mice and humans
Mean first passage times of processes driven by white shot noise
The systems driven by white shot noise are analyzed based on mean first passage times. The shot noise has exponentially distributed jump heights. The the linkage between the results and the steady state probability density function of the process are presented
Non-invasive ventilation in obesity hypoventilation syndrome without severe obstructive sleep apnoea
Background Non-invasive ventilation (NIV) is an effective form of treatment in patients with obesity hypoventilation syndrome (OHS) who have concomitant severe obstructive sleep apnoea (OSA). However, there is a paucity of evidence on the efficacy of NIV in patients with OHS without severe OSA. We performed a multicentre randomised clinical trial to determine the comparative efficacy of NIV versus lifestyle modification (control group) using daytime arterial carbon dioxide tension (PaCO2) as the main outcome measure. Methods Between May 2009 and December 2014 we sequentially screened patients with OHS without severe OSA. Participants were randomised to NIV versus lifestyle modification and were followed for 2 months. Arterial blood gas parameters, clinical symptoms, health-related quality of life assessments, polysomnography, spirometry, 6-min walk distance test, blood pressure measurements and healthcare resource utilisation were evaluated. Statistical analysis was performed using intention-to-treat analysis. Results A total of 365 patients were screened of whom 58 were excluded. Severe OSA was present in 221 and the remaining 86 patients without severe OSA were randomised. NIV led to a significantly larger improvement in PaCO2 of -6 (95% CI -7.7 to -4.2) mm Hg versus -2.8 (95% CI -4.3 to -1.3) mm Hg, (p<0.001) and serum bicarbonate of -3.4 (95% CI -4.5 to -2.3) versus -1 (95% CI -1.7 to -0.2 95% CI) mmol/L (p<0.001). PaCO2 change adjusted for NIV compliance did not further improve the inter-group statistical significance. Sleepiness, some health-related quality of life assessments and polysomnographic parameters improved significantly more with NIV than with lifestyle modification. Additionally, there was a tendency towards lower healthcare resource utilisation in the NIV group. Conclusions NIV is more effective than lifestyle modification in improving daytime PaCO2, sleepiness and polysomnographic parameters. Long-term prospective studies are necessary to determine whether NIV reduces healthcare resource utilisation, cardiovascular events and mortality
The medicine selection process in four large university hospitals in Brazil: Does the DTC have a role?
Implications For The Origin Of GRB 051103 From LIGO Observations
We present the results of a LIGO search for gravitational waves (GWs)
associated with GRB 051103, a short-duration hard-spectrum gamma-ray burst
(GRB) whose electromagnetically determined sky position is coincident with the
spiral galaxy M81, which is 3.6 Mpc from Earth. Possible progenitors for
short-hard GRBs include compact object mergers and soft gamma repeater (SGR)
giant flares. A merger progenitor would produce a characteristic GW signal that
should be detectable at the distance of M81, while GW emission from an SGR is
not expected to be detectable at that distance. We found no evidence of a GW
signal associated with GRB 051103. Assuming weakly beamed gamma-ray emission
with a jet semi-angle of 30 deg we exclude a binary neutron star merger in M81
as the progenitor with a confidence of 98%. Neutron star-black hole mergers are
excluded with > 99% confidence. If the event occurred in M81 our findings
support the the hypothesis that GRB 051103 was due to an SGR giant flare,
making it the most distant extragalactic magnetar observed to date.Comment: 8 pages, 3 figures. For a repository of data used in the publication,
go to: https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=15166 . Also see
the announcement for this paper on ligo.org at:
http://www.ligo.org/science/Publication-GRB051103/index.ph
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