Federated Learning's Blessing: FedAvg has Linear Speedup

Federated learning (FL) learns a model jointly from a set of participating devices without sharing each other's privately held data. The characteristics of non-iid data across the network, low device participation, and the mandate that data remain private bring challenges in understanding the convergence of FL algorithms, particularly in regards to how convergence scales with the number of participating devices. In this paper, we focus on Federated Averaging (FedAvg)--the most widely used and effective FL algorithm in use today--and provide a comprehensive study of its convergence rate. Although FedAvg has recently been studied by an emerging line of literature, it remains open as to how FedAvg's convergence scales with the number of participating devices in the FL setting--a crucial question whose answer would shed light on the performance of FedAvg in large FL systems. We fill this gap by establishing convergence guarantees for FedAvg under three classes of problems: strongly convex smooth, convex smooth, and overparameterized strongly convex smooth problems. We show that FedAvg enjoys linear speedup in each case, although with different convergence rates. For each class, we also characterize the corresponding convergence rates for the Nesterov accelerated FedAvg algorithm in the FL setting: to the best of our knowledge, these are the first linear speedup guarantees for FedAvg when Nesterov acceleration is used. To accelerate FedAvg, we also design a new momentum-based FL algorithm that further improves the convergence rate in overparameterized linear regression problems. Empirical studies of the algorithms in various settings have supported our theoretical results

Faster Ray Tracing through Hierarchy Cut Code

We propose a novel ray reordering technique to accelerate the ray tracing process by encoding and sorting rays prior to traversal. Instead of spatial coordinates, our method encodes rays according to the cuts of the hierarchical acceleration structure, which is called the hierarchy cut code. This approach can better adapt to the acceleration structure and obtain a more reliable encoding result. We also propose a compression scheme to decrease the sorting overhead by a shorter sorting key. In addition, based on the phenomenon of boundary drift, we theoretically explain the reason why existing reordering methods cannot achieve better performance by using longer sorting keys. The experiment demonstrates that our method can accelerate secondary ray tracing by up to 1.81 times, outperforming the existing methods. Such result proves the effectiveness of hierarchy cut code, and indicate that the reordering technique can achieve greater performance improvement, which worth further research

Palliative local treatment of bone metastases by 125I seed brachytherapy under DynaCT guidance: single-center experience

PURPOSEWe aimed to evaluate the clinical benefit of 125I seed brachytherapy under DynaCT guidance for palliative local treatment of bone metastases.METHODSFrom December 2014 to September 2017, 82 patients with painful bone metastases, who experienced treatment failure using standard strategies or rejected treatment were enrolled in this retrospective study. All patients underwent 125I seed brachytherapy under DynaCT guidance. Technical success, visual analogue scale (VAS), numerical rating scale (NRS), verbal rating scale (VRS), Karnofsky performance status (KPS) and complications were analyzed.RESULTSThe success rate of 125I seed implantation was 100%. The VAS and NRS scores for the most severe pain were 7.0 (5.0–9.0) and 8.0 (6.0–9.0) before brachytherapy. The pain scores assessed every 2 hours gradually decreased within 12 hours (p < 0.001). A comparison of KPS scores showed that patients had significantly better quality of life on weeks 1, 4, and 8 than on week 0 (p < 0.001). The associated complications were mild subcutaneous hemorrhage 25.6% (21/82), fever 7.3% (6/82), minor displacement of radioactive seeds 5.0% (4/82), pathologic fracture 2.4% (2/82), and local skin reaction 2.4% (2/82). After symptomatic treatment, all complications were relieved. Minor displacement of radioactive seeds did not cause damage to adjacent tissues. No serious life-threatening complications occurred in the study group.CONCLUSIONDynaCT-guided 125I seed implantation is a safe and effective method for palliation of painful bone metastases from cancer after failure or rejection of conventional treatments

Ataxia-telangiectasia in China: a case report of a novel ATM variant and literature review

BackgroundAtaxia-telangiectasia (A-T) is a multisystem genetic disorder involving ataxia, oculocutaneous telangiectasia, and immunodeficiency caused by biallelic pathogenic variants in the ATM gene. To date, most ATM variants have been reported in the Caucasian population, and few studies have focused on the genotype–phenotype correlation of A-T in the Chinese population. We herein present a Chinese patient with A-T who carries compound heterozygous variants in the ATM gene and conducted a literature review for A-T in China.Case presentationA 7-year-old Chinese girl presented with growth retardation, ataxia, medium ocular telangiectasia, cerebellar atrophy, and elevated serum alpha-fetoprotein (AFP) level, which supported the suspicion of A-T. Notably, the serum levels of immunoglobulins were all normal, ruling out immunodeficiency. Exome sequencing and Sanger sequencing revealed two likely pathogenic ATM variants, namely NM_000051.4: c.4195dup (p.Thr1399Asnfs*15) and c.6006 + 1G&gt;T (p.?), which were inherited from her father and mother, respectively. From the Chinese literature review, we found that there was a marked delay in the diagnosis of A-T, and 38.9% (7/18) of A-T patients did not suffer from immunodeficiency in China. No genotype–phenotype correlation was observed in this group of A-T patients.ConclusionThese results extend the genotype spectrum of A-T in the Chinese population and imply that the diagnosis of A-T in China should be improved

I-GUIDE Climbers: A Model for Multidisciplinary Academic Labs for Early Career Development

In this paper, we propose a new form of multidisciplinary academic collaboration that goes beyond the traditional modes of knowledge exchange. We argue that most research collaboration today is based on interactions between closely related disciplines, in which researchers share data, methods, and insights within a common framework or problem. However, such collaboration may not foster the development of the communication and management skills essential to a multi-disciplinary research career. Therefore, we suggest establishing a network of researchers from divergent, yet complementary, disciplines who are interested in improving these skills through regular interactions and feedback. The main goal of this network is not to conduct research or address a specific research question, but to create a learning environment where researchers can enhance their interdisciplinary competencies through the diverse perspectives and experiences of their peers. Moreover, a multidisciplinary group of early-career professionals provides a space for collaborations to flourish. In this paper, we also offer practical advice for researchers who wish to join or create a similar network

UAV back-track in GPS unreliable environment

Unmanned aerial vehicle (UAV) is thriving in recent years. Sensors equipped on a UAV enhance its versatility of aiding human’s work instead of just flying. Function like pathing following and back-tracking is in demand for monitoring and transportation. In this thesis, we propose a pipeline of a monocular back-tracking system based on computer vision, which deftly combines classic pose estimation algorithms with optimization methods to locate UAV itself and provide a navigation target with a 6-dimension pose. This system is proved to have stable performance in a static scenario.Master of Science (Computer Control and Automation

Measurement on the Harmony Coefficient of Agro-eco-economic System in the Arid Region

On the basis of the present research progress of ecological agriculture, we take Minle County and Linze County located in the middle reaches of Heihe River as the typical research units. Based on the rural social and economic data during the period of 2000-2010, theory and method of mathematical statistics are used to establish the measure theory and model of agro-eco-economic system harmony coefficient, including efficacy function, function of harmony coefficient, harmony coefficient and level of harmony coefficient. Based on the actual situation of research region, evaluation indicator system of agro-eco-economic system is established and measurement is carried out. Results show that the regional agro-eco-economic system in research region was in a serious imbalance in 2000-2013. The harmony coefficient of Minle showed a slight rise from 2000 to 2004, and then presented a fluctuating decline. Its rank of harmony coefficient experienced serious imbalance-extreme imbalance-moderate imbalance-low imbalance-serious imbalance-high imbalance. At the same time, the similar tendency happened in Linze County. The measuring results of subsystem in 2000-2013 further indicated that except that the harmony coefficient of economic subsystem in Minle County and Linze County was moderate and high, the ecological subsystem was at Level II and Level III, and social subsystem was at Level IV and Level III, in high and low imbalance status. Finally, several recommendations were put forward for optimizing agro-eco-economic system

Tighter monogamy and polygamy relations in multiqubit systems

In this paper, we investigate some monogamy and polygamy relations in terms of concurrence, Rényi α-entropy entanglement and Tsallis q-entropy entanglement. Those relations are tighter than the existing monogamy and polygamy relations. As application, we give some examples in detail