In this paper, important statistical characteristics of the ratio of double generalized-gamma random variables have been analytically evaluated. The derived results have been applied in a wireless ...powered mobile-to-mobile communication scenario, which operates in the presence of interference. The performance is investigated using the throughput criterion under two different scenarios, namely delay limited and delay tolerant transmissions. Moreover, since the links' reliability depends on the mobile nodes locations, the <inline-formula> <tex-math notation="LaTeX">2D </tex-math></inline-formula> Poisson point process is employed in order to more realistically model the physical layer behavior. The analytical results provided generalize previously reported ones, while the numerical results presented reveal the impact of various system's and channel's parameters, e.g., distance among nodes, interference, the non-linearity of the wireless medium.
The structure of the Central Andes forearc of northern Chile has been an enigma for many years. Along this region, the preservation of a long pediplain constituted by gravels and unconsolidated ...sediments has hidden the structure of the region, making it difficult to understand its tectonic evolution. The traditional and regional-scale structural models are mainly supported by outcrop-scale and local observations. To unravel the structure of this Andes region, we carried out a regional-scale study based on local and regional observations, geological mapping, and the elaboration of local and regional balanced cross-sections, thereby illustrating the geometry and distribution of the first-order structural styles. We examined four specific sectors along a regional transect: the Loa and San Salvador rivers (parallel to each other), Sierra de Limón Verde, and Cerros de Tuina. Three structural styles were identified in the hybrid thick- and thin-skinned and doubly verging fold-and-thrust belt. These styles comprise partially inverted Permian to Jurassic normal faults, thick-skinned reverse faults affecting Paleozoic crystalline basement blocks, and shallow and thin-skinned fault-related folds. The shallow and thin-skinned fault-related folds usually result from the propagation of large, thick-skinned thrust ramps into stratigraphic successions. The restoration of a regionally balanced cross section constrained by field data and the previously interpreted two-dimensional (2-D) seismic profiles suggest that much of the crustal shortenings are accommodated by the reverse reactivation of Triassic and Jurassic normal faults bounding half-graben structures. It is also accommodated by blind thrust faults, whose geometry, kinematic, and depth are debatable. However, we have proposed a large, thick-skinned thrust ramp as the structure responsible for the greater shortening in the region, along which a significant thick- to thin-skinned transition occurs. The age of the synorogenic deposits identified here is unknown, specially those exposed at the Loa and San Salvador rives, however, the basal successions exposed at the Tuina sector reported Upper Cretaceous ages, thus suggesting that the orogeny in the forearc could have started during this time spam. Regional correlations with similar synorogenic deposits recognized in neighboring regions (e.g., Salar de Atacama Basin and Coastal Cordillera) also affirm an Upper Cretaceous–Paleocene age for the initiation of the crustal contraction in the region.
•Thin-skinned fold-and-thrust belt.•The Andean forearc of northern Chile.•Basin inversion of Mesozoic rift systems.•Restoration of Andean structures.
We analyze the level crossing rate and the average fade duration of amplify and forward multihop relay networks. We first calculate exact closed-form expressions for these statistics when the ...individual links are affected by log-normal fading with arbitrary autocorrelation. Based on these expressions, we formulate a log-normal approximation to the product of N Nakagami-m independent random processes. In particular, through a proper matching of the mean, variance and the autocorrelation function, we show that the product of N Nakagami-m stochastic processes can be closely approximated by a single log-normal process. This allows us to accurately approximate the crossing statistics for the cascaded Nakagami-m fading channel in closed-form. Using this analytical framework we characterize the dynamics of the equivalent multihop channel gain for different correlation models, and study the influence of the number of hops and the relay mobility in these second order statistics.
We investigate the secrecy performance and energy-efficiency trade-offs associated to the secure communication between a full-duplex (FD) power beacon (PB) and an energy harvesting (EH) device, in ...the presence of an eavesdropper. Specifically, we analyze the feasibility of a jamming strategy implemented at the FD-PB under several practical constraints, such as imperfect self-interference (SI) cancellation, EH non-linearity, channel aging and energy-information correlation. The design of the optimal time-splitting factor for the simultaneous wireless information and power transfer (SWIPT) strategy, the adequacy of different beamforming strategies for proper system operation, and the impact of channel correlation between the energy and information transmission phases in SWIPT are thoroughly discussed. Results indicate that under practical constraints such as EH non-linearity and imperfect SI cancellation, the transmit powers at the FD-PB for the generation of energy and jamming signals are the key parameters to be optimized from both points of view: secrecy and energy efficiency. We also verify the positive impact of correlation between the energy and information links in wireless power transfer systems, from a physical layer security perspective.
Abstract
Radial velocity (RV) measurements of transiting multiplanet systems allow us to understand the densities and compositions of planets unlike those in the solar system. Kepler-102, which ...consists of five tightly packed transiting planets, is a particularly interesting system since it includes a super-Earth (Kepler-102d) and a sub-Neptune-sized planet (Kepler-102e) for which masses can be measured using RVs. Previous work found a high density for Kepler-102d, suggesting a composition similar to that of Mercury, while Kepler-102e was found to have a density typical of sub-Neptune size planets; however, Kepler-102 is an active star, which can interfere with RV mass measurements. To better measure the mass of these two planets, we obtained 111 new RVs using Keck/HIRES and Telescopio Nazionale Galileo/HARPS-N and modeled Kepler-102's activity using quasiperiodic Gaussian process regression. For Kepler-102d, we report a mass upper limit
M
d
< 5.3
M
⊕
(95% confidence), a best-fit mass
M
d
= 2.5 ± 1.4
M
⊕
, and a density
ρ
d
= 5.6 ± 3.2 g cm
−3
, which is consistent with a rocky composition similar in density to the Earth. For Kepler-102e we report a mass
M
e
= 4.7 ± 1.7
M
⊕
and a density
ρ
e
= 1.8 ± 0.7 g cm
−3
. These measurements suggest that Kepler-102e has a rocky core with a thick gaseous envelope comprising 2%–4% of the planet mass and 16%–50% of its radius. Our study is yet another demonstration that accounting for stellar activity in stars with clear rotation signals can yield more accurate planet masses, enabling a more realistic interpretation of planet interiors.
This paper investigates the impact of realistic propagation conditions on the achievable secrecy performance of multiple-input multiple-output systems in the presence of an eavesdropper (Eve). ...Specifically, we concentrate on the <inline-formula><tex-math notation="LaTeX">\kappa</tex-math></inline-formula>-<inline-formula><tex-math notation="LaTeX">\mu</tex-math></inline-formula> shadowed fading model because its physical underpinnings capture a wide range of propagation conditions, while, at the same time, it allows for a much better tractability than other state-of-the-art fading models. By considering transmit antenna selection and maximal ratio combining reception at the legitimate (Bob) and Eve's receiver sides, we study two relevant scenarios: 1) the transmitter knows Bob's channel state information (CSI) but not Eve's CSI, and 2) the transmitter is aware of the CSI of both Bob and Eve channels. For this purpose, we first obtain novel and tractable expressions for the statistics of the maximum of independent and identically distributed (i.i.d.) variates related to the legitimate channel. Based on these results, we derive novel closed-form expressions of the two aforementioned scenarios to assess the secrecy performance of the underlying system. Specifically, for cases: 1) the secrecy outage probability (SOP), the probability of strictly positive secrecy capacity (SPSC), and 2) the average secrecy capacity (ASC). Moreover, we develop analytical asymptotic expressions of the SOP and ASC in the high signal-to-noise ratio regime. In all instances, secrecy performance metrics are characterized in closed-form, without requiring the evaluation of Meijer-G or Fox-H functions. Some useful insights on how the different propagation conditions and the number of antennas impact the secrecy performance are also provided.
The recently proposed fluctuating two-ray (FTR) model is gaining momentum as a reference fading model in scenarios where two dominant specular waves are present. Despite the numerous research works ...devoted to the performance analysis under FTR fading, little attention has been paid to effectively understanding the interplay between the fading model parameters and the fading severity. According to a new scale defined in this work, which measures the hyper-Rayleigh character of a fading channel in terms of the amount of fading, the outage probability and the average capacity, we see that the FTR fading model exhibits a full hyper-Rayleigh behavior. However, the two-wave with diffuse power fading model from which the former is derived has only strong hyper-Rayleigh behavior, which constitutes an interesting new insight. We also identify that the random fluctuations in the dominant specular waves are ultimately responsible for the full hyper-Rayleigh behavior of this class of fading channels.
In this letter, we study the performance of digital communication systems considering the general and versatile <inline-formula> <tex-math notation="LaTeX">\boldsymbol {\alpha } ...</tex-math></inline-formula>-<inline-formula> <tex-math notation="LaTeX">\boldsymbol {\eta } </tex-math></inline-formula>-<inline-formula> <tex-math notation="LaTeX">\boldsymbol {\kappa } </tex-math></inline-formula>-<inline-formula> <tex-math notation="LaTeX">\boldsymbol {\mu } </tex-math></inline-formula> fading model, which was recently proposed in the literature. To this end, novel and exact expressions for the outage probability, average channel capacity, and average error rate of a variety of modulation formats are derived for arbitrary values of the fading parameters. Moreover, an asymptotic outage analysis is carried out in order to get further insight as to how the fading parameters impact system performance. Monte Carlo simulations are provided to validate the proposed analytical framework.
Inflammatory arthritis defines a family of diseases influenced by reproductive hormones. Vasoinhibin, a fragment of the hormone prolactin (PRL), has antiangiogenic and proinflammatory properties. We ...recently showed that vasoinhibin reduces joint inflammation and bone loss in severe antigen-induced arthritis (AIA) by an indirect mechanism involving the inhibition of pannus vascularization. This unexpected finding led us to hypothesize that a severe level of inflammation in AIA obscured the direct proinflammatory action of vasoinhibin while allowing the indirect anti-inflammatory effect via its antiangiogenic properties. In agreement with this hypothesis, here we show that the intra-articular injection of an adeno-associated virus type-2 vector encoding vasoinhibin reduced joint inflammation in a severe AIA condition, but elevated joint inflammation in a mild AIA model. The proinflammatory effect, unmasked in mild AIA, resulted in joint swelling, enhanced leukocyte infiltration, and upregulation of expression of genes encoding proinflammatory mediators (Il1b, Il6, Inos, Mmp3), adhesion molecule (Icam1), and chemokines (Cxcl1, Cxcl2, Cxcl3, Ccl2). Furthermore, vasoinhibin induced the expression of proinflammatory mediators and chemokines in cultured synovial fibroblasts through nuclear factor-κB. Finally, matrix metalloproteases and cathepsin D, upregulated in the arthritic joint, cleaved PRL to vasoinhibin, and vasoinhibin levels increased in the circulation of mice subjected to AIA. We suggest that vasoinhibin is generated during inflammatory arthritis and acts on synovial fibroblasts and endothelial cells to initially promote and later inhibit inflammation, respectively. These opposite effects may work together to help keep joint inflammation under balance.
Recent experimental results show that full-duplex (FD) communication is feasible provided that the residual self-interference after cancellation is close to the noise floor. In this paper, we present ...a low-complexity active self-interference cancellation technique for FD orthogonal frequency division multiplexing (OFDM) systems, which accounts for the inherent cyclostationarity of the OFDM signal in order to effectively cancel the self-interference. The method here proposed estimates the self-interference cancellation path by using a time-averaged mean-square error criterion, combined with a filtered least mean squares adaptive algorithm. Then, its performance is experimentally validated using a self-developed FD radio testbed implemented with off-the-shelf components. When combined with passive cancellation, applying the proposed technique provides enough self-interference suppression as to reach close (less than 2 dB) to the receiver noise floor.
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