This paper describes a general framework for the optimization of very large reflectarrays for space applications. It employs the generalized intersection approach as optimizing algorithm, integrating ...a number of techniques that substantially improve the baseline algorithm by accelerating computations while preserving the accuracy of the electromagnetic analysis. In particular, a learning algorithm based on support vector machines is used to obtain a surrogate model of the reflectarray unit cell accelerating the analysis more than three orders of magnitude. For the optimization, the gradient computation is accelerated by employing the technique of differential contributions on the radiated field, which avoids the use of the fast Fourier transform in the computation of the far field. Finally, to improve the cross-polarization performance, instead of optimizing the crosspolar pattern, the crosspolar discrimination or crosspolar isolation is optimized, improving both the antenna and algorithm performances. Relevant numerical examples are provided to show the capabilities of the proposed framework for a Direct Broadcast Satellite mission, showing how to design a contoured beam reflectarray with a European footprint with two different coverage zones. In addition, a complete study of computing time is carried out to analyze the impact of each technique in the optimization process.
The Antarctic Peninsula (AP) constitutes the warmest region of Antarctica, although 98% of the surface is still covered by glaciers. The region shows contrasting geographic and climatic properties, ...which have conditioned past and present glacial activity. This paper constitutes a review of the spatial and temporal patterns of paraglacial activity across the AP bridging the geomorphological and ecological perspectives. The number and extent of ice-free environments has increased since the Last Glacial Maximum, particularly during the Early Holocene and the 20th century. Following deglaciation, the redefinition of coastlines and the uplift of landmasses proceeded differently in the three sectors of AP, with maximum uplift in the western sector (40 m a.s.l.), the minimum on the north (20.4 m a.s.l.), and intermediate in the eastern sector (30 m). There are also differences in the levels of raised beaches, with the highest complexity in the northern AP (5–7 levels) and the lowest in the eastern AP (3 levels). The transition from glacial to periglacial conditions (paraglacial stage) also differed greatly between the three sectors, with the absence of rock glaciers in the western sector, the development almost exclusively of glacier-derived rock glaciers in the eastern AP, and the majority of talus-derived rock glaciers in the northern AP. The development of protalus lobes, block streams and other periglacial features was highly dependent on the cold/warm based character of individual glaciers; this characteristic determines the existence or absence of permafrost following deglaciation which, in turn, conditions the type and intensity of geomorphic processes in newly exposed ice-free areas. More recently, following the post-1950s regional warming, there have still been important differences between the three sectors in the development of paraglacial environments. Permafrost degradation has occurred in newly exposed areas, accelerating mass wasting and sediment redistribution and changing hydrological processes, especially in the northern and western AP, while sudden glacial outburst flooding has occurred in the eastern AP. The most apparent major ecological response to this recent warming is greening due to vegetation expansion, which is more evident where paraglacial and periglacial processes are less intense. The accurate characterization of the different paraglacial responses existing in the AP enables a better understanding of future environmental responses in this climatically sensitive region, where climate models forecast significant environmental change for during forthcoming decades.
Vascular calcification has a global health impact that is closely linked to bone loss. The Receptor Activator of Nuclear Factor Kappa B (RANK)/RANK ligand (RANKL)/osteoprotegerin (OPG) system, ...fundamental for bone metabolism, also plays an important role in vascular calcification. The Leucine-rich repeat-containing G-protein-coupled receptor 4 (LGR4), a novel receptor for RANKL, regulates bone remodeling, and it appears to be involved in vascular calcification. Besides RANKL, LGR4 interacts with R-spondins (RSPOs), which are known for their roles in bone but are less understood in vascular calcification. Studies were conducted in rats with chronic renal failure fed normal or high phosphorus diets for 18 weeks, with and without control of circulating parathormone (PTH) levels, resulting in different degrees of aortic calcification. Additionally, vascular smooth muscle cells (VSMCs) were cultured under non-calcifying (1 mM phosphate) and calcifying (3 mM phosphate) media with different concentrations of PTH. To explore the role of RANKL in VSMC calcification, increasing concentrations of soluble RANKL were added to non-calcifying and calcifying media. The effects mediated by RANKL binding to its receptor LGR4 were investigated by silencing the LGR4 receptor in VSMCs. Furthermore, the gene expression of the RANK/RANKL/OPG system and the ligands of LGR4 was assessed in human epigastric arteries obtained from kidney transplant recipients with calcification scores (Kauppila Index). Increased aortic calcium in rats coincided with elevated systolic blood pressure, upregulated Lgr4 and Rankl gene expression, downregulated Opg gene expression, and higher serum RANKL/OPG ratio without changes in Rspos gene expression. Elevated phosphate in vitro increased calcium content and expression of Rankl and Lgr4 while reducing Opg. Elevated PTH in the presence of high phosphate exacerbated the increase in calcium content. No changes in Rspos were observed under the conditions employed. The addition of soluble RANKL to VSMCs induced genotypic differentiation and calcification, partly prevented by LGR4 silencing. In the epigastric arteries of individuals presenting vascular calcification, the gene expression of RANKL was higher. While RSPOs show minimal impact on VSMC calcification, RANKL, interacting with LGR4, drives osteogenic differentiation in VSMCs, unveiling a novel mechanism beyond RANKL-RANK binding.
Non-Orthogonal Multiple Access (NOMA) has emerged as a promising strategy for increasing spectral efficiency in wireless multiuser communications. The performance of NOMA highly depends on the users' ...channel conditions, being enhanced when these are significantly different, i.e., one strong user and one weak user. On the contrary, rate fairness is compromised when users present similar channel conditions since the maximization of the sum capacity may result in the allocation of most resources to one user. In general, this problem can be avoided with correct user grouping. However, there are scenarios, e.g., picocells or femtocells, where finding users with distinctive channel conditions is not always possible. In this paper, we study the application of beamforming in a two-user Multiple-Input-Single-Output (MISO) downlink NOMA system to achieve rate fairness through channel shaping even when the conditions of both users are similar. The proposed formulation includes the effect of Near-Field (NF) radiation, which yields an accurate modeling of the problem at hand in a small-cell scenario. We use an optimization algorithm to jointly calculate both the power allocation and the complex weights to be applied to the elements of a given array. Numerical simulations across scenarios with distinctive or similar channel conditions show that the proposed approach outperforms alternative NOMA methods in ensuring rate fairness. Additionally, it yields improved overall rates compared to Far-Field (FF) formulation-based modelling and beamforming Time Division Multiple Access (TDMA) solutions.
Purpose
To investigate the short and medium term efficacy and patient outcomes of DIAM spinal stabilization system on back pain, disability, leg pain and quality of life.
Methods
165 patients were ...enrolled; 146 patients with a single level disc herniation (L2 to L5) were randomized: 75 investigational (herniectomy and DIAM) and 71 control (herniectomy alone) treated and followed up for 24 months.
Results
Significant improvements overtime (
P
< 0.001) in both groups but not significantly different between groups for visual analog scale (VAS) back pain at 6 months (investigational −3.97 ± 2.55 vs control–3.37 ± 3.15,
P
= 0.228) and Oswestry Disability Index (ODI) at 12 months (−38.55 ± 20.10 vs −37.19 ±
22.61, P
= 0
.7
19). For both outcomes, there was no statistically significant difference between the groups, at all postoperative time points. Although the enrolment ended before the intended sample size (308 patients) was reached, the number of patients reaching the VAS back pain minimally clinically important difference (MCID) of ≥2.2 at 6 months was higher in the investigational (79.4 % vs control 57.1 %,
P
= 0.008). These results were sustained throughout 24 months (82.8 vs 64.4 %,
P
< 0.05). In average, surgical duration (
P
< 0.001), blood loss (
P
= 0.029) and skin incision (
P
< 0.001) in the investigational were 10 min longer, 22.5 ml greater and 2.0 cm wider than control group (median values). Improved tertiary outcomes from BL to 24 mo in both groups (investigational vs control): VAS leg pain (mean decrease −6.41 ± 2.57 to −6.41 vs −5.61 ± to −3.30); improved quality of life (SF-36: 20.68 ± 9.44 vs 16.90 ± 10.74); pain medication reduction: 56.7 vs 47.9 %; return to work: 45.7 vs 38.0 %. Adverse event rates: 68.5 % investigational and 66.2 % control.
Conclusions
This is the first randomized controlled trial to report equivalent efficacy and safety of herniectomy with or without DIAM spinal stabilizing device. Leg pain, back pain and the level of disability were not significantly different between groups; however, number of patients reaching the MCID for back pain was significantly higher in the investigational group at 6 through 24 months.
Given their highly polarized morphology and functional singularity, neurons require precise spatial and temporal control of protein synthesis. Alterations in protein translation have been implicated ...in the development and progression of a wide range of neurological and neurodegenerative disorders, including Huntington's disease (HD). In this study we examined the architecture of polysomes in their native brain context in striatal tissue from the zQ175 knock-in mouse model of HD. We performed 3D electron tomography of high-pressure frozen and freeze-substituted striatal tissue from HD models and corresponding controls at different ages. Electron tomography results revealed progressive remodelling towards a more compacted polysomal architecture in the mouse model, an effect that coincided with the emergence and progression of HD related symptoms. The aberrant polysomal architecture is compatible with ribosome stalling phenomena. In fact, we also detected in the zQ175 model an increase in the striatal expression of the stalling relief factor EIF5A2 and an increase in the accumulation of eIF5A1, eIF5A2 and hypusinated eIF5A1, the active form of eIF5A1. Polysomal sedimentation gradients showed differences in the relative accumulation of 40S ribosomal subunits and in polysomal distribution in striatal samples of the zQ175 model. These findings indicate that changes in the architecture of the protein synthesis machinery may underlie translational alterations associated with HD, opening new avenues for understanding the progression of the disease.
Display omitted
•In-tissue 3D electron tomography allows the analysis of polysomal organization.•Neuronal polysomal architecture undergoes progressive compaction in HD mice.•Densely packed polysomes in HD are compatible with ribosome stalling phenomena.•eIF5A ribosome stalling relief factors are activated in the striatum of HD mice.•Polysomal sedimentation gradients show increase in free 40S subunits in HD striatum.
Wireless communications have attracted great interest from the industry due to its lower costs and the possibility of enabling new use cases. The new use cases are commonly related to mobile ...robotics, such as Unmanned Aerial Vehicles or terrestrial robots. The design of wireless systems for these use cases requires deep knowledge of the channel behavior and therefore the use of channel sounders that are able to measure the phase and gain of the channel is mandatory. However, channel sounders require very precise synchronization, which is typically implemented through a wired connection between the nodes. As a result, the mobility of the nodes is constrained to the length of the synchronization wire. In this paper, we present the design and implementation of a portable 802.11-based channel sounder that exploits a sub-nanosecond wireless time synchronization scheme. Thanks to the wireless synchronization, the channel sounder can operate as a channel sounder with wired synchronization, being able to measure synchronized channel impulse response samples. From these samples, relevant channel parameters can be extracted, including the Power Delay Profile, Doppler spectrum, and channel delay. The channel sounder presents several advantages compared to a conventional channel sounder with wire synchronization, such as smaller size and weight, simpler and more flexible operation, and it does not constraint the movement of the environment or nodes. The verification of the channel sounder through a wireless channel emulator and the measurement carried out in an industrial facility confirm its feasibility for industrial wireless and other applications.
The Western Massif of the Picos de Europa (latitude 43° N, longitude 4–5° W) includes some of the highest peaks in the Cantabrian Mountains. This massif was heavily glaciated during the Last ...Glaciation, though the post-glacial environmental evolution is still poorly understood. Using a complementary geomorphological and sedimentological approach, we have reconstructed the environmental events occurred in this massif since the last Pleistocene glaciation. The geomorphological distribution of glacial landforms suggests the occurrence of four main glacial stages: maximum glacial advance, glacial expansion after the maximum advance, Late Glacial and Little Ice Age. Moreover, a 5.4-m long sedimentary sequence was retrieved from the karstic depression of Belbín providing a continuous record of the paleoenvironmental conditions in this area since the Last Glaciation until nowadays. This section suggests that the maximum glacial expansion occurred at a minimum age of 37.2 ka cal BP, significantly prior to the global Last Glacial Maximum. Subsequently, periglacial processes prevailed in the mid lands of the massif until glaciers expanded between 22.5 and 18.7 ka cal BP. Following the melting of the glaciers, a shallow lake appeared in the Belbín depression. Lake sediments do not show evidence of a cold stage during the Late Glacial, when moraine systems formed at higher locations. The terrestrification of this lake started at 8 ka cal BP and the area turned into grassland. At 4.9 ka cal BP the existence of charcoal particles in the sediments of Belbín sequence reveals the onset of human occupation in the massif through the use of fire activity for grazing purposes. Finally, the presence of moraines inside the highest northern cirques shows evidence of the last glacial phase that occurred during the Little Ice Age cold event. Since then, the warming climate has led to the melting of these glaciers and periglacial processes prevail in the high lands of the massif.
•We reconstructed past environments in Picos de Europa since the Last Glaciation.•The maximum expansion of glaciers occurred at a minimum age of 37.2 ka cal BP.•Four glacial stages: maximum advance, second maximum advance, Late Glacial and LIA.•These stages were parallel to environmental changes (periglacial, lake, peatland).•Fire activity started at 4.9 ka cal BP, onset of human impact in the high lands.
A study of interference management in a Single-Input-Single-Output (SISO) two-user broadcast scenario by adjusting the circularity coefficient of discrete constellations is presented. Previously ...researched techniques for the same problem, namely the combination of PAM and QAM constellations, are reviewed as instances of the improper approach. The presented investigation further extends to the exploration of other combinations. Remarkably, all results presented in this letter are based on figures of merit of discrete constellations (mutual information, error probability, and minimum distance between symbols) rather than on formulas extrapolated from Gaussian signaling. Findings indicate that certain conclusions drawn previously for Improper Gaussian Signaling (IGS) in a similar setting hold for finite input constellations, though some vary.
Fibromyalgia (FM) is characterized by chronic widespread pain, as well as anxiety, sadness, and depression. These symptoms are present in most patients and have a negative impact on their daily, ...family, and social life. The role of neurotransmitters in the pathophysiology of FM has been extensively discussed. The scientific evidence shows that levels of serotonin are decreased in patients with FM. Numerous studies support the beneficial effects that moderate wine consumption has on the body, with cardiovascular, endocrine, bone, and muscle improvements.
The objective of this pilot study was to assess whether light consumption of red wine improves the main symptoms of FM.
The study consisted of an experimental study with a control group with a total of 60 women diagnosed with FM following the American College of Rheumatology's criteria. The experimental group ingested 15 g of alcohol per day, in the form of red wine, over a period of four weeks. The outcome measures were: the level of pain in tender points, sadness, anxiety, depression, and quality of life. The assessments tools were: tender point graphics, the visual analogue scale (for the assessment of pain and sadness), the Hamilton Anxiety Scale, the Hamilton Depression Rating Scale, and the Fibromyalgia Impact Questionnaire. The measurements were completed before and after the consumption of red wine. In addition, the differences between groups were evaluated in terms of drug consumption in the pre-intervention and follow-up phases.
Statistically significant improvements were obtained in the wine ingestion group for the variables of pain (
= 0.038), tender points (
< 0.001), and anxiety (
= 0.028). An improvement in the mean values was observed in favor of the experimental group for the variables of sadness, depression, and quality of life. The differences observed in the changes seen in the groups that were in favor of the wine ingestion group should not be attributed to the consumption of drugs but to the fact that the experimental group had a light intake of red wine.
The results of this pilot study suggest a potential relationship between alcohol intake through the light consumption of red wine as part of the patients' diet and the improvement of the main symptoms of fibromyalgia. Future studies are necessary to confirm these preliminary data; a bigger sample and a controlled diet should be considered, and the mechanisms through which improvements are achieved should be analyzed.
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