A new ADMM algorithm for the Euclidean median and its application to robust patch regression

The Euclidean Median (EM) of a set of points $\Omega$ in an Euclidean space is the point x minimizing the (weighted) sum of the Euclidean distances of x to the points in $\Omega$. While there exits no closed-form expression for the EM, it can nevertheless be computed using iterative methods such as the Wieszfeld algorithm. The EM has classically been used as a robust estimator of centrality for multivariate data. It was recently demonstrated that the EM can be used to perform robust patch-based denoising of images by generalizing the popular Non-Local Means algorithm. In this paper, we propose a novel algorithm for computing the EM (and its box-constrained counterpart) using variable splitting and the method of augmented Lagrangian. The attractive feature of this approach is that the subproblems involved in the ADMM-based optimization of the augmented Lagrangian can be resolved using simple closed-form projections. The proposed ADMM solver is used for robust patch-based image denoising and is shown to exhibit faster convergence compared to an existing solver.Comment: 5 pages, 3 figures, 1 table. To appear in Proc. IEEE International Conference on Acoustics, Speech, and Signal Processing, April 19-24, 201

Internames: a name-to-name principle for the future Internet

We propose Internames, an architectural framework in which names are used to identify all entities involved in communication: contents, users, devices, logical as well as physical points involved in the communication, and services. By not having a static binding between the name of a communication entity and its current location, we allow entities to be mobile, enable them to be reached by any of a number of basic communication primitives, enable communication to span networks with different technologies and allow for disconnected operation. Furthermore, with the ability to communicate between names, the communication path can be dynamically bound to any of a number of end-points, and the end-points themselves could change as needed. A key benefit of our architecture is its ability to accommodate gradual migration from the current IP infrastructure to a future that may be a ubiquitous Information Centric Network. Basic building blocks of Internames are: i) a name-based Application Programming Interface; ii) a separation of identifiers (names) and locators; iii) a powerful Name Resolution Service (NRS) that dynamically maps names to locators, as a function of time/location/context/service; iv) a built-in capacity of evolution, allowing a transparent migration from current networks and the ability to include as particular cases current specific architectures. To achieve this vision, shared by many other researchers, we exploit and expand on Information Centric Networking principles, extending ICN functionality beyond content retrieval, easing send-to-name and push services, and allowing to use names also to route data in the return path. A key role in this architecture is played by the NRS, which allows for the co-existence of multiple network "realms", including current IP and non-IP networks, glued together by a name-to-name overarching communication primitive.Comment: 6 page

Is Explicit Congestion Notification usable with UDP?

We present initial measurements to determine if ECN is usable with UDP traffic in the public Internet. This is interesting because ECN is part of current IETF proposals for congestion control of UDPbased interactive multimedia, and due to the increasing use of UDP as a substrate on which new transport protocols can be deployed. Using measurements from the author’s homes, their workplace, and cloud servers in each of the nine EC2 regions worldwide, we test reachability of 2500 servers from the public NTP server pool, using ECT(0) and not-ECT marked UDP packets. We show that an average of 98.97% of the NTP servers that are reachable using not-ECT marked packets are also reachable using ECT(0) marked UDP packets, and that ~98% of network hops pass ECT(0) marked packets without clearing the ECT bits. We compare reachability of the same hosts using ECN with TCP, finding that 82.0% of those reachable with TCP can successfully negotiate and use ECN. Our findings suggest that ECN is broadly usable with UDP traffic, and that support for use of ECN with TCP has increased

Studies on cucurbit viruses in Madras State. IV. Some aspects of the relationships of Melon Mosaic Virus strain to its three aphid vectors

Melon Mosaic Virus (MMV) was non-persistent in its three aphid vectors. The pre-acquisition fasting threshold, acquisition threshold and the inoculation feeding threshold were 5 minutes, 10 seconds and 60 seconds respectively for Myzus persicae, 15 minutes, 30 seconds and 3 minutes respectively for Aphis gossypii, 60 minutes, 60 seconds and 5 minutes respectively for A. nerii. The optimum number of viruliferous aphids per plant for maximum transmission was 30 in all the vectors. Increasing the number of aphids above this optimum decreased the percentage transmission of the virus. In the case of myzus persicae, the reduction in the percentage transmission was conspicuous when 240 aphids per plant were used whereas in A. nerii the decrease was noticed even when 100 aphids per plant were used. The percentage transmission by fasted aphids was more than by the non-fasted ones. Persistance of the virus during fasting was for 90, 45 and 30 minutes respectively in M. persicae, A. gossypii and A. nerii while during feeding it was 30, 15 and 10 minutes respectively. The aphid vectors were ranked in the following descending order of transmission efficiency: Myzus persicae, Aphis gossypii and A. nerii. The length of the pre-acquisition fasting period varied inversely as the efficiency. More efficient the vector, shorter was the fasting period. The acquisition threshold and incoulation feeding threshold also varied inversely as the efficiency of the vector. The fall in the efficiency of transmission when the number of aphid vector was increased above the optimum was considered to be due to a salivary inhibitor. Apterous forms of the aphid vectors were more efficient transmitters of the viruses than the alate forms. It was concluded that all aphids have a salivary inactivator, the quantity secreted varied from species to species, the efficiency of transmission being inversely correlated with the quantity of inhibitor secreted