A fundamental problem that confronts peer-to-peer applications is to efficiently locate the node that stores a particular data item. This paper presents Chord, a distributed lookup protocol that addresses this problem. Chord provides support for just one operation: given a key, it maps the key onto a node. Data location can be easily implemented on top of Chord by associating a key with each data item, and storing the key/data item pair at the node to which the key maps. Chord adapts efficiently as nodes join and leave the system, and can answer queries even if the system is continuously changing. Results from theoretical analysis, simulations, and experiments show that Chord is scalable, with communication cost and the state maintained by each node scaling logarithmically with the number of Chord nodes.

Chord: A scalable peer-to-peer lookup service for internet applications

This paper presents the design and evaluation of Pastry, a scalable, distributed object location and routing substrate for wide-area peer-to-peer ap- plications. Pastry performs application-level routing and object location in a po- tentially very large overlay network of nodes connected via the Internet. It can be used to support a variety of peer-to-peer applications, including global data storage, data sharing, group communication and naming. Each node in the Pastry network has a unique identifier (nodeId). When presented with a message and a key, a Pastry node efficiently routes the message to the node with a nodeId that is numerically closest to the key, among all currently live Pastry nodes. Each Pastry node keeps track of its immediate neighbors in the nodeId space, and notifies applications of new node arrivals, node failures and recoveries. Pastry takes into account network locality; it seeks to minimize the distance messages travel, according to a to scalar proximity metric like the number of IP routing hops. Pastry is completely decentralized, scalable, and self-organizing; it automatically adapts to the arrival, departure and failure of nodes. Experimental results obtained with a prototype implementation on an emulated network of up to 100,000 nodes confirm Pastry's scalability and efficiency, its ability to self-organize and adapt to node failures, and its good network locality properties.

/pdf/pastry-scalable-decentralized-object-location-and-routing-1u2equbbbp.pdf

Pastry: Scalable, Decentralized Object Location, and Routing for Large-Scale Peer-to-Peer Systems

Hash tables - which map "keys" onto "values" - are an essential building block in modern software systems. We believe a similar functionality would be equally valuable to large distributed systems. In this paper, we introduce the concept of a Content-Addressable Network (CAN) as a distributed infrastructure that provides hash table-like functionality on Internet-like scales. The CAN is scalable, fault-tolerant and completely self-organizing, and we demonstrate its scalability, robustness and low-latency properties through simulation.

https://www.cs.sjtu.edu.cn/~gchen/course/acn/Reading/CAN.pdf

A scalable content-addressable network

A review of the geologic history of the Himalayan-Tibetan orogen suggests that at least 1400 km of north-south shortening has been absorbed by the orogen since the onset of the Indo-Asian collision at about 70 Ma. Significant crustal shortening, which leads to eventual construction of the Cenozoic Tibetan plateau, began more or less synchronously in the Eocene (50–40 Ma) in the Tethyan Himalaya in the south, and in the Kunlun Shan and the Qilian Shan some 1000–1400 km in the north. The Paleozoic and Mesozoic tectonic histories in the Himalayan-Tibetan orogen exerted a strong control over the Cenozoic strain history and strain distribution. The presence of widespread Triassic flysch complex in the Songpan-Ganzi-Hoh Xil and the Qiangtang terranes can be spatially correlated with Cenozoic volcanism and thrusting in central Tibet. The marked difference in seismic properties of the crust and the upper mantle between southern and central Tibet is a manifestation of both Mesozoic and Cenozoic tectonics. The form...

Geologic Evolution of the Himalayan-Tibetan Orogen

Reliability at massive scale is one of the biggest challenges we face at Amazon.com, one of the largest e-commerce operations in the world; even the slightest outage has significant financial consequences and impacts customer trust. The Amazon.com platform, which provides services for many web sites worldwide, is implemented on top of an infrastructure of tens of thousands of servers and network components located in many datacenters around the world. At this scale, small and large components fail continuously and the way persistent state is managed in the face of these failures drives the reliability and scalability of the software systems.This paper presents the design and implementation of Dynamo, a highly available key-value storage system that some of Amazon's core services use to provide an "always-on" experience. To achieve this level of availability, Dynamo sacrifices consistency under certain failure scenarios. It makes extensive use of object versioning and application-assisted conflict resolution in a manner that provides a novel interface for developers to use.

/pdf/dynamo-amazon-s-highly-available-key-value-store-2ozfk43ou4.pdf

Dynamo: amazon's highly available key-value store


 The content of γ-aminobutyric acid (GABA) in human serum has been proved to be closely related to depression, so the rapid, sensitive, highly selective and accurate determination of GABA is of great significance for the objective diagnosis of depression. In this study, a molecularly imprinted electrochemical sensor based on high-performance magnetically functionalized reduced graphene oxide (MRGO) was constructed for the sensitive detection of GABA in the serum of depressed mice. Using MRGO modified the flexible electrode (ITO-PET), 2,4-dinitrofluorobenzene derivative of GABA as the template and pyrrole with self-polymerization effect as the functional monomer and cross-linking agent, the molecularly imprinted sensor MIP/MRGO/ITO-PET was successfully constructed by simple electropolymerization and stirring elution. Under the optimal construction process, the sensor realized the accurate detection of GABA in the range of 250 pM~100 μM, and the detection limit was as low as 1.25×10-10 M (S/N=3). The simultaneous possession of high sensitivity and selectivity, good stability, repeatability and reproducibility enables this sensor to be successfully applicable for the determination of GABA in mice serum. The results showed that the sensor is expected to provide a basis for objective diagnosis of depression in clinic.

A Novel Flexible Electrochemical Molecular Imprinted Sensor for the Determination of GABA in Serum of Depressed Mice

Background and Objective Liposuction is an effective treatment for fat disposition in lymphedema. Blood transfusion has been seldom investigated in lymphedema liposuction surgery. The purpose of the study was to analyze clinical factors associated with blood transfusion in liposuction surgery of lymphedema patients and compare the autologous and allogeneic transfusion patterns. Methods A total of 1,187 cases of liposuction due to lymphedema were recruited. Demographic, laboratory tests and operation information were collected. Patients were divided into a transfusion and a non-transfusion group. Different transfusion patterns were compared and analyzed. Results Between the two groups, there is a significant difference in postoperative hemoglobin levels, and as well as gender, age, surgery duration, body weight change, intraoperative transfusion volume and blood loss, hospital length of stay, and surgical site distribution. There is a significant difference in the comparison of hospital stay length, autologous transfusion volume, combined allogeneic volume, operative blood loss, intraoperative transfusion volume, and change in hemoglobin levels between predonation and acute normovolemic hemodilution (ANH) transfusion. In comparison with the allogeneic transfusion-only patients, the mean allogeneic transfusion volume in either ANH group, predonated transfusion group, or mixed group is statistically lower. Allogeneic transfusion volume in the predonated-only group is significantly lower than that of either the ANH-only group or the mixing ANH with predonation group. Ordinary least squares regression analysis suggests that autologous transfusion in the ANH-only mode is statistically associated with allogeneic transfusion. Conclusions This study described the blood transfusion in lymphedema liposuction surgery and compared autologous and allogeneic transfusion patterns in these patients. Autologous transfusion can reduce the transfusion volume of allogeneic blood and might be a beneficial mode of transfusion in these patients.

Does Autologous Transfusion Decrease Allogeneic Transfusion in Liposuction Surgery of Lymphedema Patients?

In this paper, we focus on the power-delay tradeoff for downlink transmission systems. In particular, we target to design the adaptive modulation scheme that achieves the optimal power-delay tradeoff under practical concerns, such as the practical power consumption model of a base station and the dynamics of user trafﬁc. The optimal modulation level selection problem is formulated in a Markov decision problem and a cross-layer approach is adopted to take both queue and channel dynamics into consideration. Simulation results show that the proposed policy achieves about 20% power saving for the same delay performance, compared with ﬁxed modulation level schemes. In addition, the impact of the practical power consumption model under dynamic trafﬁc does change the optimal modulation level selection philosophy.

Power-Delay Tradeoff Improvement with Adaptive Modulation Scheme under Practical Power Model

Reconstructing long‐term forest age of China by combining forest inventories, satellite‐based forest age and forest cover datasets

This paper proposes a landslide detection method combining gray level co-occurrence matrix (GLCM) and polarization decomposition technique. The proposed method makes full use of the characteristics of the SAR image and combines the polarization information with the texture feature. Landslide candidate areas were identified using GLCM and final landslide areas were determined using polarization decomposition techniques. The data used for evaluation is taken from Guangyuan City, Sichuan, China. The proposed method successfully detects the changes of two SLC sentinel-1A C-band VV and VH dual polarization SAR images before and after the landslide, which proves the effectiveness of this method.

Yan Chen

Papers

A Novel Flexible Electrochemical Molecular Imprinted Sensor for the Determination of GABA in Serum of Depressed Mice

Does Autologous Transfusion Decrease Allogeneic Transfusion in Liposuction Surgery of Lymphedema Patients?

Power-Delay Tradeoff Improvement with Adaptive Modulation Scheme under Practical Power Model

Reconstructing long‐term forest age of China by combining forest inventories, satellite‐based forest age and forest cover datasets

Novel Landslide Extraction Method of SAR Image Based on Change Detection and Polarization Decomposition