Online Network Slicing for Real Time Applications in Large-scale Satellite Networks

In this work, we investigate resource allocation strategy for real time communication (RTC) over satellite networks with virtual network functions. Enhanced by inter-satellite links (ISLs), in-orbit computing and network virtualization technologies, large-scale satellite networks promise global coverage at low-latency and high-bandwidth for RTC applications with diversified functions. However, realizing RTC with specific function requirements using intermittent ISLs, requires efficient routing methods with fast response times. We identify that such a routing problem over time-varying graph can be formulated as an integer linear programming problem. The branch and bound method incurs $\mathcal{O}(|\mathcal{L}^{\tau}| \cdot (3 |\mathcal{V}^{\tau}| + |\mathcal{L}^{\tau}|)^{|\mathcal{L}^{\tau}|})$ time complexity, where $|\mathcal{V}^{\tau}|$ is the number of nodes, and $|\mathcal{L}^{\tau}|$ is the number of links during time interval ${\tau}$. By adopting a k-shortest path-based algorithm, the theoretical worst case complexity becomes $O(|\mathcal{V}^{\tau}|! \cdot |\mathcal{V}^{\tau}|^3)$. Although it runs fast in most cases, its solution can be sub-optimal and may not be found, resulting in compromised acceptance ratio in practice. To overcome this, we further design a graph-based algorithm by exploiting the special structure of the solution space, which can obtain the optimal solution in polynomial time with a computational complexity of $\mathcal{O}(3|\mathcal{L}^{\tau}| + (2\log{|\mathcal{V}^{\tau}|}+1) |\mathcal{V}^{\tau}|)$. Simulations conducted on starlink constellation with thousands of satellites corroborate the effectiveness of the proposed algorithm.Comment: Accepted to appear in IEEE ICC 202

Translational and rotational dynamical heterogeneities in granular systems

We use X-ray tomography to investigate the translational and rotational dynamical heterogeneities of a three dimensional hard ellipsoids granular packing driven by oscillatory shear. We find that particles which translate quickly form clusters with a size distribution given by a power-law with an exponent that is independent of the strain amplitude. Identical behavior is found for particles that are translating slowly, rotating quickly, or rotating slowly. The geometrical properties of these four different types of clusters are the same as those of random clusters. Different cluster types are considerably correlated/anticorrelated, indicating a significant coupling between translational and rotational degrees of freedom. Surprisingly these clusters are formed already at time scales that are much shorter than the $\alpha-$relaxation time, in stark contrast to the behavior found in glass-forming systems.Comment: 9 page

Structural and Topological Nature of Plasticity in Sheared Granular Materials

Upon mechanical loading, granular materials yield and undergo plastic deformation. The nature of plastic deformation is essential for the development of the macroscopic constitutive models and the understanding of shear band formation. However, we still do not fully understand the microscopic nature of plastic deformation in disordered granular materials. Here we used synchrotron X-ray tomography technique to track the structural evolutions of three-dimensional granular materials under shear. We establish that highly distorted coplanar tetrahedra are the structural defects responsible for microscopic plasticity in disordered granular packings. The elementary plastic events occur through flip events which correspond to a neighbor switching process among these coplanar tetrahedra (or equivalently as the rotation motion of 4-ring disclinations). These events are discrete in space and possess specific orientations with the principal stress direction.Comment: 26 pages, 11 figures, 2 tables, to be published in Nature Communication

Streamflow and Sediment Declines in a Loess Hill and Gully Landform Basin Due to Climate Variability and Anthropogenic Activities

Streamflow and sediment runoff are important indicators for the changes in hydrological processes. In the context of environmental changes, decreases in both streamflow and sediment (especially in the flood season) are often observed in most of the tributaries of the middle Yellow River in China’s Loess Plateau. Understanding the effect of human activities could be useful for the management of soil and water conservation (SWC) and new constructions. In this paper, changes in streamflow and sediment during the flood season (June–September) of the 1966–2017 period in a typical loess hill and gully landform basin were analyzed. Basin-wide rainfall of the flood season decreased nonsignificantly with an average rate of −0.6 mm/flood season for the whole study period by using the trend-free pre-whitening based Mann–Kendall trend test, while the decreasing rate was weakened on the time scale. A remarkable warming trend (1985–1999) and two decreasing trends (1966–1984 and 2000–2017) were observed, and the overall increasing trend could be found in air temperature series with a rate of 0.01 °C/flood season during the study period. Statistical models were developed to describe the rainfall-runoff and rainfall-sediment processes in the pre-impact period (when the hydrological series was stationary). Furthermore, the relative effects of climate variability and human activities on hydrological changes were quantified. Results proved the dominant role of human activities (versus climate variability) on the reductions of both streamflow and sediment load. The relative contribution of human activities to streamflow decrease was 84.6% during the post-impact period 1995–2017, while the contributions were 48.8% and 80.1% for two post-impact periods (1982–1996 and 1997–2017), respectively, to the reduction of sediment load. Besides, the effect of the exclusion of anomalous streamflow or sediment events on change-point detection was also analyzed. It indicated that the anomalous events affect the detection of change points and should be given full consideration in order to decide whether to remove them in the change-point detection. Otherwise, the full series with anomalous samples will completely affect the attribution results of hydrological changes. We also suggest that large-scale SWC measures with different construction quality and operational life could intercept and relieve most floods and high sediment concentration processes, but may amplify the peaks of streamflow and sediment when the interception capacities are exceeded under the condition of extreme rainstorm events

GPC analyses of transgenic tuber protein extracts.

<p>A) Activity distribution of SnRK1 from overexpression lines of <i>stKIN</i> of GPC fractions from B4 to C11. B) Proteins present in the indicated fractions from the GPC column were separated by SDS-PAGE and then probed with HA antibody in immunoblot analyses. The peak elution volumes of the molecular mass standards analyzed in the same GPC protocol are indicated at the top. The size of each fraction is 0.5ml, and the corresponding elution volume of B4 and C11 is 0.5 ml and 17.5, respectively.</p

Starch content in total soluble extracts of potato tubers of transgenic plants and wild-type.

<p>(A) Starch content in overexpression lines the of <i>stKIN</i>, <i>stKINβ1</i>, <i>stKINβ2</i>, <i>stKINγ</i>, <i>stKINβγ</i> and wild-type control. (B) Starch content in the RNAi lines of <i>stKIN</i>, <i>stKINβ1</i>, <i>stKINβ2</i>, <i>stKINγ</i>, <i>stKINβγ</i> and wild-type control. Means of three independent samples are presented. The asterisk indicates a significant difference between means at <i>p</i> = 0.05.</p

SnRK1 activity of purified protein from the overexpression transgenic plants of <i>StKIN</i>, <i>stKINβ1</i>, <i>stKINβ2</i>, <i>stKINγ</i> or <i>stKINβγ</i>.

<p>The total protein samples are from tubers of transgenic plants of <i>StKIN</i>, <i>stKINβ1</i>, <i>stKINβ2</i>, <i>stKINγ</i> or <i>stKINβγ</i>. During enzyme activity assay, boiled enzymes were used as negative control, the values reported on the graph are background-subtracted. Means of three independent samples are presented.</p

Existing hip joint disease is associated with an increased incidence of hip fracture in adults: A retrospective survey of 9710 individuals from a single center

Objective: In hip disease patients, pain and movement restrictions might cause changes in bone strength and increase the likelihood of falls, finally leading to hip fracture. The aim of this study was to identify the incidence of, characteristics of and risk factors for hip fracture in patients with existing hip disease. Methods: This was a retrospective cohort study. Patients with existing hip disease treated at both outpatient and inpatient departments of our institute were identified by searching the electronic medical record system and followed retrospectively for the occurrence of hip fracture. Demographic and clinical characteristics, such as age, sex and kind of primary hip disease, were collected from the electronic medical record system. The incidence and timing of hip fracture were estimated, and a Cox regression model was built to identify the independent risk factors for hip fracture in these patients. Results: A total of 9710 eligible patients were included. After a mean follow-up of 3.97 years, hip fractures were identified in 95 patients, for an estimated incidence of hip fracture of 978.37 per 100,000 patients. The femoral neck was involved in 49 fractures (51.58 %), and the femoral trochanter was involved in 45 fractures (47.37 %). Four independent risk factors and one protective factor for hip fracture in patients with hip diseases were identified: age (HR = 1.116, 95 % CI = 1.094–1.138), the presence of osteonecrosis of the femoral head (HR = 2.201, 95 % CI = 1.217–3.980), a lower Harris hip score (HR = 0.966, 95 % CI = 0.949–0.982), a history of previous hip surgery (HR = 2.126, 95 % CI = 1.304–3.466) and the use of walking aids (HR = 0.588, 95 % CI = 0.354–0.975). A scoring system with a total score of 20 points was built, which included all of the above risk factors. The predictive scores for a low risk (estimated incidence of hip fracture ≤30 %), a moderate risk (estimated incidence of hip fracture 31 %–69 %), and a high risk (estimated incidence of hip fracture ≥70 %) of hip fracture were ≤8.5 points, 9.0–13.0 points and ≥13.5 points, respectively. Conclusion: The incidence of hip fracture in the special population of patients with existing hip disease was determined. Elderly patients, patients with a history of hip surgery, patients with osteonecrosis and patients with poor Harris hip scores were at increased risk of hip fracture. In patients with a predictive score greater than 9 points, indicating a moderate to high risk of hip fracture, the use of a walking aid might reduce the risk of hip fracture