On a general convergence for Broyden like update method

The role of Broyden's method as a powerful quasi-Newton method for solving unconstrained optimization problems or a system of nonlinear algebraic equations is well known. We offer here a general convergence criterion for a method akin to Broyden's method in Rn. The approach is different from those of other convergence proofs which are available only for the direct prediction methods

Decentralized optimization over noisy, rate-constrained networks: Achieving consensus by communicating differences

In decentralized optimization, multiple nodes in a network collaborate to minimize the sum of their local loss functions. The information exchange between nodes required for this task, is often limited by network connectivity. We consider a setting in which communication between nodes is hindered by both (i) a finite rate-constraint on the signal transmitted by any node, and (ii) additive noise corrupting the signal received by any node. We propose a novel algorithm for this scenario: Decentralized Lazy Mirror Descent with Differential Exchanges (DLMD-DiffEx), which guarantees convergence of the local estimates to the optimal solution under the given communication constraints. A salient feature of DLMD-DiffEx is the introduction of additional proxy variables that are maintained by the nodes to account for the disagreement in their estimates due to channel noise and rate-constraints. Convergence to the optimal solution is attained by having nodes iteratively exchange these disagreement terms until consensus is achieved. In order to prevent noise accumulation during this exchange, DLMD-DiffEx relies on two sequences; one controlling the power of the transmitted signal, and the other determining the consensus rate. We provide clear insights on the design of these two sequences which highlights the interplay between consensus rate and noise amplification. We investigate the performance of DLMD-DiffEx both from a theoretical perspective as well as through numerical evaluations.Comment: 15 pages, 6 figure

Determine characteristics requirement for the surrogate road edge objects for road departure mitigation testing

Road departure mitigation system (RDMS), a vehicle active safety feature, uses road edge objects to determine potential road departure. In the U.S., 45%, 16%, and 15% of car-mile (traffic flow * miles) roads have grass, metal guardrail, and concrete divider as road edge, respectively. It is difficult to test RDMS with real roadside objects. Lightweight and crashable surrogate roadside objects that have representative radar, LIDAR and camera characteristics of real objects have been developed for testing. This paper describes the identification of automotive radar, LIDAR, and visual characteristics of metal guardrail, concrete divider, and grass. These characteristics will be referenced for designing and fabricating the representative surrogate objects for RDMS testing. Colors and types of the roadside objects were identified from 24,735 randomly sampled locations in the US using Google street view images. The radar and LIDAR parameters were measured using 24GHz/77GHz radar and 350-2500nm IR spectrometer

Development of Surrogate Grass for the Evaluation of Vehicle Road Departure Mitigation Systems

Vehicle road departure mitigation system (RDMS), as new active safety technology, has been introduced into the market in recent years. This system can detect roadside objects and road edges to reduce the risk of roadway departure crashes. To evaluate and improve the performance of RDMS, surrogates of roadside objects, which have the same camera, radar, and LiDAR characteristics of the real objects, need to be developed. Grass is the most common road edge in the U.S. as seen from the real road data. This paper describes the development of surrogate grass. The LiDAR (infrared) and radar characteristics of the selected artificial turf (grass) are obtained and compared with those of real grass. In order to make the surrogate grass match the real grass in the view of sensors (LiDAR, radar and camera), a special color coating with high reflectance material is applied to the artificial turf. Both LiDAR and radar measurements confirmed that the surrogate grass closely match the key characteristics of the real grass. Five grass colors and eighteen color patterns were identified based on 1,021 grass road-edge samples from all states of the U.S. 300-meter long surrogate grass was made and successfully used on the test track for the vehicle RDMS evaluation

Triple-Decker Sandwich Complexes of Tungsten with Planar and Puckered Middle Decks

International audienceA triple-decker complex of tungsten, [(Cp*W){μ-η:η-BHCo(CO)}(H)] (; Cp* = η-CMe), with a planar middle deck has been isolated by thermolysis of an in situ formed intermediate from the reaction of Cp*WCl and LiBH with Co(CO). In addition, we have also isolated another triple-decker complex, [(Cp*W){μ-η:η-BHFe(CO)}(H)] (), having a puckered central ring, from a similar reaction with Fe(CO). Clusters and are unprecedented examples of a triple-decker complex having a 24-valence electron with bridging hydrogen atoms

Visual outcome after endovascular intervention in Takayasu arteritis

Takayasu arteritis is a chronic multisystem vasculitis which has been known to be associated with myriad of ophthalmological manifestations. Steroids and immunomodulators are the mainstay of medical management in early stages of disease. We report the case of a 15-year-old girl with complaints of diminution of vision in both the eyes. Her ophthalmic examination suggested a diagnosis of Takayasu retinopathy with posterior ischemic optic neuropathy in her left eye and ocular ischemic syndrome in the right eye. Digital subtraction angiography revealed a significant narrowing of major vessels originating from the arch of aorta and the left vertebral artery. She underwent left subclavian artery and left vertebral artery balloon angioplasty followed by left vertebral artery stenting. Her vision improved significantly postprocedure, suggesting that endovascular intervention in the later stages of disease is a promising treatment modality for Takayasu retinopathy

Effect of transportation on the quality of the donor corneal buttons

The aim of this study is to see the effect of transportation on corneoscleral buttons and to correlate them with the weight of ice used during transportation. This is a prospective cross-sectional study. A total of 119 corneas were graded using slit-lamp examination and specular microscopy before and after transportation. Groups were made based on the weight of ice used during transportation and the number of hours of storage in McCarey-Kaufman (MK) media. The overall median percentage of endothelial cell loss (ECL) was 11.33%. The median percentage of ECL was significantly more with <500 g of ice as compared to ≥500 g (13.6% vs. 7.56%) with P = 0.006. There was no significant difference in percentage of ECL on storage in MK media for ≤48 h, ≤72 h, and ≤96 h. Corneal buttons have ECL on storage and transportation which can be minimized using the appropriate weight of ice during transportation

Labor analgesia in parturients of fetal growth restriction having raised umbilical Doppler vascular indices

Background and Aims: Fetuses with abnormal umbilical blood flow are at a higher risk of adverse perinatal outcome than those with normal flow. Epidural analgesia (EA) has shown to decrease villous vascular resistance in preeclamptic women during labor. The present study evaluates the effects of epidural ropivacaine and intramuscular (IM) tramadol on Doppler blood flow in parturients with fetal growth restriction and raised umbilical artery (UmA) blood flow. Material and Methods: In this prospective nonrandomized comparative study, 36 term parturients with sonographic evidence of UmA systolic-diastolic (S-D) ratio ≥3 were enrolled. Parturients received either continuous epidural ropivacaine 0.2% or 1 mg/kg IM tramadol 4–6 hourly. Doppler flow parameters of UmA and bilateral uterine arteries (UtAs) were measured at 0, 1, and 6 h of labor analgesia. Doppler indices change with time during labor analgesia was assessed as the primary outcome. Change of Doppler indices of UtAs, Apgar score, and cord blood gases was considered as secondary measures. Results: Data from thirty laboring women who completed the study were analyzed. The pulsatility index, resistance index, and S-D ratio in UmA and right UtA reduced significantly with continuous epidural infusion during first 6 h of labor. However, these values increased or unchanged with tramadol administration. Better neonatal pH and base deficit (P = 0.039) were observed with EA. Conclusions: Continuous epidural ropivacaine causes improved fetoplacental circulation in parturients with growth-restricted fetuses having raised Doppler indices during labor analgesia. We also found better neonatal outcome with continuous infusion of epidural ropivacaine as compared to IM tramadol