74 research outputs found
Plasma protein adsorption on Fe<sub>3</sub>O<sub>4</sub>-PEG nanoparticles activates the complement system and induces an inflammatory response
Q-switched mode locking noise-like pulse generation from a thulium-doped all-fiber laser based on nonlinear polarization rotation
Q-switched mode locking (QML) noise-like pulse (NLP) emission from an all-fiber thulium-doped laser based on the nonlinear polarization rotation effect is reported. The QML emission is obtained in a cavity with net anomalous dispersion in a pump power interval in between the CW laser threshold and the threshold of the NLP regime. Highest-energy QML pulses were observed with a repetition rate of 812 kHz with a pump power of 520 mW at the optical wavelength of 1881.09 nm. A maximum overall energy of 460 nJ at an average output power of 6.4 mW was reached, which corresponds to a burst of mode-locked noise-like sub-pulses with 8.7 ns of pulse duration within a QML envelope of 11 ÎĽs. These results demonstrate unconventional pulse operation regime of NLPs and provide insights into the dynamics of mode-locked fiber lasers
Sub-200-kHz single soliton generation in a long ring Er-fiber laser with strict polarization control by using twisted fiber
In the present work we demonstrate a novel single-soliton ultra-low pulse repetition frequency passively modelocked erbium-doped fiber laser. We mitigate the residual linear birefringence of fiber by fiber twist to achieve a strict control of polarization. For mode-locking the nonlinear polarization rotation (NPR) was used. Special technique was applied to reduce the overdriving of NPR that allows the generation of single soliton in ultra-long cavity. The strict control of polarization yields a stable relation between the polarization state of the pulses propagating in the cavity and the regimes of generation. A 192.12-kHz train of soliton pulses was obtained with pulse duration of 4.7 ps at 1560.1 nm, the average power was 29 ÎĽW and the estimated peak power was Ě´30.8 W with an energy of 150.9 pJ
Non-minimally Coupled Cosmological Models with the Higgs-like Potentials and Negative Cosmological Constant
We study dynamics of non-minimally coupled scalar field cosmological models
with Higgs-like potentials and a negative cosmological constant. In these
models the inflationary stage of the Universe evolution changes into a
quasi-cyclic stage of the Universe evolution with oscillation behaviour of the
Hubble parameter from positive to negative values. Depending on the initial
conditions the Hubble parameter can perform either one or several cycles before
to become negative forever.Comment: 22 pages, 6 figures, v4:Section 2 expanded, references added,
accepted for publication in Class. Quant. Gra
Unified description of the dynamics of quintessential scalar fields
Using the dynamical system approach, we describe the general dynamics of
cosmological scalar fields in terms of critical points and heteroclinic lines.
It is found that critical points describe the initial and final states of the
scalar field dynamics, but that heteroclinic lines which give a more complete
description of the evolution in between the critical points. In particular, the
heteroclinic line that departs from the (saddle) critical point of perfect
fluid-domination is the representative path in phase space of quintessence
fields that may be viable dark energy candidates. We also discuss the attractor
properties of the heteroclinic lines, and their importance for the description
of thawing and freezing fields.Comment: Minor changes to the text and two new figures, main conclusions
unchanged. 12 pages, 11 figures, uses RevTe
Long cavity ring fiber mode-locked laser with decreased net value of nonlinear polarization rotation
We investigate a new configuration of a mode-locked fiber laser by using a nonlinear polarization rotation-based design to generate soliton pulses with low repetition rate. Unlike with previously reported configurations, we introduce a Faraday mirror after the first half of the cavity length to counteract the nonlinear polarization rotation effects. The total cavity length is 437 m including a 400-m long twisted SMF-28 fiber. The fiber was twisted to cancel the linear birefringence and to ensure that the polarization ellipticity is not altered as the pulse travels along the fiber. The strict control of polarization yields a stable relation between the polarization state of the pulses propagating in the cavity and the regimes of generation. Depending on the polarization state we observed three different emission regimes, the single soliton regime (SR), conventional noise-like pulses (NLP) and noise-like square-waveform pulse (NLSWP). In the SR, a 467.2 kHz train of solitons was obtained with pulse duration of 2.9 ps at 1558.7 nm
Possible dark energy imprints in gravitational wave spectrum of mixed neutron-dark-energy stars
In the present paper we study the oscillation spectrum of neutron stars
containing both ordinary matter and dark energy in different proportions.
Within the model we consider, the equilibrium configurations are numerically
constructed and the results show that the properties of the mixed
neuron-dark-energy star can differ significantly when the amount of dark energy
in the stars is varied. The oscillations of the mixed neuron-dark-energy stars
are studied in the Cowling approximation. As a result we find that the
frequencies of the fundamental mode and the higher overtones are strongly
affected by the dark energy content. This can be used in the future to detect
the presence of dark energy in the neutron stars and to constrain the
dark-energy models.Comment: 17 pages, 8 figures, LaTe
Tension between SN and BAO: current status and future forecasts
Using real and synthetic Type Ia SNe (SNeIa) and baryon acoustic oscillations
(BAO) data representing current observations forecasts, this paper investigates
the tension between those probes in the dark energy equation of state (EoS)
reconstruction considering the well known CPL model and Wang's low correlation
reformulation. In particular, here we present simulations of BAO data from both
the the radial and transverse directions. We also explore the influence of
priors on Omega_m and Omega_b on the tension issue, by considering 1-sigma
deviations in either one or both of them. Our results indicate that for some
priors there is no tension between a single dataset (either SNeIa or BAO) and
their combination (SNeIa+BAO). Our criterion to discern the existence of
tension (sigma-distance) is also useful to establish which is the dataset with
most constraining power; in this respect SNeIa and BAO data switch roles when
current and future data are considered, as forecasts predict and spectacular
quality improvement on BAO data. We also find that the results on the tension
are blind to the way the CPL model is addressed: there is a perfect match
between the original formulation and that by the low correlation optimized, but
the errors on the parameters are much narrower in all cases of our exhaustive
exploration, thus serving the purpose of stressing the convenience of this
reparametrization.Comment: 21 pages, under review in JCA
Household food insecurity, diet, and weight status in a disadvantaged district of Ho Chi Minh City, Vietnam: a cross-sectional study
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