Accelerating Incremental Gradient Optimization with Curvature Information

This paper studies an acceleration technique for incremental aggregated gradient ({\sf IAG}) method through the use of \emph{curvature} information for solving strongly convex finite sum optimization problems. These optimization problems of interest arise in large-scale learning applications. Our technique utilizes a curvature-aided gradient tracking step to produce accurate gradient estimates incrementally using Hessian information. We propose and analyze two methods utilizing the new technique, the curvature-aided IAG ({\sf CIAG}) method and the accelerated CIAG ({\sf A-CIAG}) method, which are analogous to gradient method and Nesterov's accelerated gradient method, respectively. Setting $\kappa$ to be the condition number of the objective function, we prove the $R$ linear convergence rates of $1 - \frac{4c_0 \kappa}{(\kappa+1)^2}$ for the {\sf CIAG} method, and $1 - \sqrt{\frac{c_1}{2\kappa}}$ for the {\sf A-CIAG} method, where $c_0,c_1 \leq 1$ are constants inversely proportional to the distance between the initial point and the optimal solution. When the initial iterate is close to the optimal solution, the $R$ linear convergence rates match with the gradient and accelerated gradient method, albeit {\sf CIAG} and {\sf A-CIAG} operate in an incremental setting with strictly lower computation complexity. Numerical experiments confirm our findings. The source codes used for this paper can be found on \url{http://github.com/hoitowai/ciag/}.Comment: 22 pages, 3 figures, 3 tables. Accepted by Computational Optimization and Applications, to appea

May Adiponectin be considered as a Novel Cardiometabolic Biomarker?

This study was designed to evaluate the interaction between total adiponectin (ADPN) and metabolic syndrome (MetS) on cardiac changes in 135 subjects with and without MetS, subgrouped according to normal or low ADPN. Left ventricular internal diameter (LVID/h), LV mass (LVM), LVM index (LVMI), interventricular septal thickness (IVST), relative wall thickness (RWT) and LV ejection fraction (EF) by echocardiography and diastolic parameters, by pulsed-wave Doppler were calculated. BMI, LVM, LVMI, LVID/h, IVST and RWT values were significantly (p<0.05) higher in both groups with low ADPN. Prevalence of left ventricular hypertrophy (p<0.001) and coronary artery disease (p<0.01) was significantly higher in both low ADPN groups. LVMI correlated directly with BMI (p<0.001), (p<0.001), MetS (p<0.001) and inversely with ADPN (p<0.0001). ADPN and BMI resulted independently associated with LVMI. In conclusion, our data suggest that hypoadiponectinemia might be considered a novel “cardiometabolic biomarker”. Accordingly, circulating ADPN might become a new target in the management of cardiometabolic syndrome

Teardown analysis of a ten cell bipolar nickel-hydrogen battery

Design studies have identified bipolar nickel-hydrogen batteries as an attractive storage option for high power, high voltage applications. A pre-prototype Ni-H2 battery was designed, assembled and tested in the early phases of a concept verification program. The initial stack was built with available hardware and components from past programs. The stack performed well. After 2000 low-earth-orbit cycles the stack was dismantled in order to allow evaluation and analysis of the design and components. The results of the teardown analysis and recommended modifications are discussed

Energy-efficient broadcasting with cooperative transmissions in wireless sensor networks

[[abstract]]Broadcasting is a method that allows the distributed nodes in a wireless sensor network to share its data efficiently among each other. Due to the limited energy supplies of a sensor node, energy efficiency has become a crucial issue in the design of broadcasting protocols. In this paper, we analyze the energy savings provided by a cooperative form of broadcast, called the Opportunistic Large Arrays (OLA), and compare it to the performance of conventional multi-hop networks where no cooperation is utilized for transmission. The cooperation in OLA allows the receivers to utilize for detection the accumulation of signal energy provided by the transmitters that are relaying the same symbol. In this work, we derive the optimal energy allocation policy that minimizes the total energy cost of the OLA network subject to the SNR (or BER) requirements at all receivers. Even though the cooperative broadcast protocol provides significant energy savings, we prove that the optimum assignment for cooperative networks is an NP-complete problem and, thus, requires high computational complexity in general. We then introduce several suboptimal yet scalable solutions and show the significant energy-savings that one can obtain even with the approximate solutions.[[fileno]]2030137030017[[department]]電機工程學

On multiple access for distributed dependent sources: a content-based group testing approach

[[abstract]]In this paper we consider the multiple access problem with distributed dependent sources. We derive the optimal designs for the case of N correlated binary sources whose data is modelled as a two-state Markov chain. The solution can be classified as a group testing technique where data values at the sensors are determined through the successive refinements of the tests over smaller groups. The tests form, progressively, an accurate map of the sensor data at the central receiver. We derive the conditions on the parameters of the data model for which the group testing approach is superior to time sharing. In contrast to standard multiple access techniques, this is the first method proposed for data retrieval from distributed dependent sources which is content-based rather than user-based.[[fileno]]2030137030013[[department]]電機工程學

Non \ue8 pi\uf9 quella di una volta. La mafia e le attivit\ue0 estorsive in Sicilia

Il volume presenta i risultati di una ricerca volta alla descrizione dei fenomeni estorsivi e della loro intensit\ue0 in Sicilia, raccontando, sulla base di appositi parametri oggettivi e di valutazioni soggettive degli esponenti del mondo delle associazioni e delle forze dell\u2019ordine, le aree pi\uf9 esposte, quelle meno esposte, quelle dove i fenomeni hanno una rilevanza residuale, in una fase in cui i sodalizi mafiosi sono sempre pi\uf9 pressati dall\u2019azione di contrasto. Per raggiungere questo obiettivo ci si \ue8 avvalsi di strumenti qualitativi e dati quantitativi, approfondendo l\u2019analisi delle trasformazioni delle condotte estorsive durante la crisi, concentrandosi in modo specifico su casi emersi nell\u2019ambito di recenti inchieste giudiziarie. Il libro ricostruisce anche la prospettiva e le difficolt\ue0 di alcuni imprenditori siciliani che, dopo aver pagato il pizzo, hanno scelto di denunciare i propri estorsori e di collaborare con le istituzioni

A multidisciplinary approach to grapevine zoning using GIS technology: An example of thermal data elaboration

Research NoteIn this study we suggest a multidisciplinary approach to zoning based on G.I.S. technology. An example of thermal data elaboration (air temperature) combined with the information derived from the heat requirements of 22 varieties is presented, based on an experiment conducted in an area of the province of Benevento (Campania region, southern Italy). The method combines thermal informations with the Amerine-Winkler bioclimatic index, to obtain a subdivision of the considered territory into five areas, according their thermal suitability. Through the model it was possible to create a map of the optimum thermal suitability of the considered varieties in the various zones of the studied territory.

Traumatic anterior dislocation of a prosthetic knee, from trauma to delayed onset of vascular injury

Anterior dislocation of a prosthetic knee is a rare event. Only few episodes have been described in the past and have never been linked with neurovascular injury. This could lead orthopaedic surgeons to focus on the implant instability factors and underrate other complications. The authors report a case of a patient who experienced popliteal artery dissection 80 hours after traumatic anterior knee dislocation of a previously well-functioning total knee arthroplasty. Given that there is a lack of clinical cases that have established guidelines for management of this problem, the authors have focused on the importance of performing computed tomography angiography in the management of an anterior traumatic knee dislocation of a prosthetic knee