A Novel Family of Adaptive Filtering Algorithms Based on The Logarithmic Cost

We introduce a novel family of adaptive filtering algorithms based on a relative logarithmic cost. The new family intrinsically combines the higher and lower order measures of the error into a single continuous update based on the error amount. We introduce important members of this family of algorithms such as the least mean logarithmic square (LMLS) and least logarithmic absolute difference (LLAD) algorithms that improve the convergence performance of the conventional algorithms. However, our approach and analysis are generic such that they cover other well-known cost functions as described in the paper. The LMLS algorithm achieves comparable convergence performance with the least mean fourth (LMF) algorithm and extends the stability bound on the step size. The LLAD and least mean square (LMS) algorithms demonstrate similar convergence performance in impulse-free noise environments while the LLAD algorithm is robust against impulsive interferences and outperforms the sign algorithm (SA). We analyze the transient, steady state and tracking performance of the introduced algorithms and demonstrate the match of the theoretical analyzes and simulation results. We show the extended stability bound of the LMLS algorithm and analyze the robustness of the LLAD algorithm against impulsive interferences. Finally, we demonstrate the performance of our algorithms in different scenarios through numerical examples.Comment: Submitted to IEEE Transactions on Signal Processin

Stochastic Subgradient Algorithms for Strongly Convex Optimization over Distributed Networks

We study diffusion and consensus based optimization of a sum of unknown convex objective functions over distributed networks. The only access to these functions is through stochastic gradient oracles, each of which is only available at a different node, and a limited number of gradient oracle calls is allowed at each node. In this framework, we introduce a convex optimization algorithm based on the stochastic gradient descent (SGD) updates. Particularly, we use a carefully designed time-dependent weighted averaging of the SGD iterates, which yields a convergence rate of $O\left(\frac{N\sqrt{N}}{T}\right)$ after $T$ gradient updates for each node on a network of $N$ nodes. We then show that after $T$ gradient oracle calls, the average SGD iterate achieves a mean square deviation (MSD) of $O\left(\frac{\sqrt{N}}{T}\right)$. This rate of convergence is optimal as it matches the performance lower bound up to constant terms. Similar to the SGD algorithm, the computational complexity of the proposed algorithm also scales linearly with the dimensionality of the data. Furthermore, the communication load of the proposed method is the same as the communication load of the SGD algorithm. Thus, the proposed algorithm is highly efficient in terms of complexity and communication load. We illustrate the merits of the algorithm with respect to the state-of-art methods over benchmark real life data sets and widely studied network topologies

Comparison of Seasonal Cycles of Phytoplankton Chlorophyll, Aerosols, Winds and Sea-Surface Temperature off Somalia

In climate research, an important task is to characterize the relationships between Essential Climate Variables (ECVs). Here, satellite-derived data sets have been used to examine the seasonal cycle of phytoplankton (chlorophyll concentration) in the waters off Somalia, and its relationship to aerosols, winds and Sea Surface Temperature (SST). Chlorophyll-a (Chl-a) concentration, Aerosol Optical Thickness (AOT), Ångström Exponent (AE), Dust Optical Thickness (DOT), SST and sea-surface wind data for a 16-year period were assembled from various sources. The data were used to explore whether there is evidence to show that dust aerosols enhance Chl-a concentration in the study area. The Cross Correlation Function (CCF) showed highest positive correlation (r2 = 0.3) in the western Arabian Sea when AOT led Chl-a by 1–2 time steps (here, 1 time step is 8 days). A 2 × 2◦ box off Somalia was selected for further investigations. The correlations of alongshore wind speed, Ekman Mass Transport (EMT) and SST with Chl-a were higher than that of AOT, for a lag of 8 days. When all four variables were considered together in a multiple linear regression, the increase in r2 associated with the AOT is only about 0.02, a consequence of covariance among AOT, SST, EMT and alongshore wind speed. The AOT data show presence of dust aerosols most frequently during the summer monsoon season (June–September). When the analyses were repeated for the dust aerosol events, the correlations were generally lower, but still significant. Again, the inclusion of DOT in the multiple linear regression increased the correlation coefficient by only 2%, indicating minor enhancement in Chl-a concentration. Interestingly, during summer monsoon season, there is a higher probability of finding more instances of positive changes in Chl-a after one time step, regardless of whether there is dust aerosol or not. On the other hand, during the winter monsoon season (November–December) and rest of the year, the probability of Chl-a enhancement is higher when dust aerosol is present than when it is absent. The phase relationship in the 8-day climatologies of Chl-a and AOT (derived from NASA’s SeaWiFS and MODIS-A ocean colour processing chain) showed that AOTled Chl-a for most of the summer monsoon season, except when Chl-a was very high, during which time, Chl-a led AOT. The phase shift in the Chl-a and AOT climatological relationship at the Chl-a peak was not observed when AOT from Aerosol Climate Change Initiative (Aerosol-CCI) was used

Total Synthesis of 6,7-Dimethyl-N-Methyl Aziridinomitosene

Mitomycin C (MC) is a naturally occurring antitumor agent isolated from a soil bacterium. MC is effective against solid hypoxic tumors that respond poorly to radiotherapy, such as colorectal, gastric, and lung tumors. Also, it has a role in the treatment of bladder, head and neck, and non-small cell lung cancers in combination with other chemotherapeutic. MC and other members of the mitomycin family of antitumor agents fight cancer by forming DNA interstrand crosslinks (ICLs), which leads to apoptosis. In order to form ICLs, MC requires a reductive activation step that produces reactive oxygen species. This activation step is proposed to lead to adverse side effects, such as myelosuppression and hemolytic uremic syndrome. Aziridinomitosenes (AZMs) are structurally related to MC and are believed to form during in vivo reduction of MC. AZMs are relatively stable but are more sensitive than the parent mitomycins due to an activated aziridine ring. Consequently, AZMs do not require the reductive activation step in order to alkylate DNA. The purpose of this work is to synthesize and study an AZM that is substituted with methyl groups at two potential electrophilic sites. It is hypothesized that certain synthetic AZMs crosslink DNA under non-reductive conditions as a result of a nucleophilic activation sequence involving the quinone ring. To test this hypothesis, analogs were prepared that would either reduce the rate of the activation step or prevent it from occurring. The synthetic route starts with commercially available reagents to form an oxazole, followed by the addition of a protected aldehyde that is converted to the required aziridine ring via a Mitsunobu reaction. Once the aziridine ring is formed, all of the reaction conditions must be conducted using mild conditions in order to prevent ring-opening. The completion of the synthesis and formation of the tetracyclic core was achieved by performing an oxazolium salt/azomethine ylide [3+2] cycloaddition sequence. This sequence was conducted multiple times, and the highest yield obtained was 44%. The final steps were the most challenging, requiring several transformations to accomplish a deprotection and oxidation to give a diketone that was oxidized to a quinone. Finally, the carbamate was attached in two steps using FmocNCO to yield the desired AZM product in an overall yield of 0.04% from the starting diol over the 22 step reaction sequence. The stability of the AZM was tested in buffered methanolic solutions, and the results were compared to other aziridinomitosenes. While unsubstituted AZMs decompose in basic solutions, the C6/C7 dimethyl AZM showed high stability under these conditions

Performance Indices and Physiological Changes in Pearl Guinea Fowls (Numida Meleagris) Supplemented with Molasses Through Drinking Water

. The study was aimed at evaluating the performance indices and physiologic changes in pearl Guinea fowls (Numida meleagris) supplemented with molasses through drinking water. A total of thirty-two (n=32) day-old pearl Guinea fowls raised to 12-week-old were used for the study. The fowls were randomly allocated to two groups (control and experimental) of 16 fowls each, with each having two replicates. Experimental fowls were given 5 mL molasses per litre of drinking water for 8 weeks, while control fowls were given only drinking water. Performance indices which include: feed consumption, water intake and percentage weight gain were measured. Rectal temperature was measured and blood samples were collected to evaluate the changes in haematological parameters, serum triiodothyronine (T3) and thyroxine (T4) concentrations. Results revealed that the molasses-treated fowls had significantly (P<0.05) higher percentage weight gain, blood total protein, packed cell volume and mean corpuscular volume compared to control. However, the feed consumptionwas significantly lower (P<0.05) in the molasses-treated fowls compared to control. In both groups, rectal temperature increased significantly (P<0.05) during the afternoon hours and was lower (P<0.05) in molasses-treated fowls than control during the evening hours. There was no significant difference in other haematological parameters, serum glucose, T4 and T3 betweengroups. In conclusion, molasses supplementation decreased feed consumption, improved body weight gain and enhanced nutritional status and erythropoiesis in Guinea fowls

Ovarian cancer cell line panel (OCCP): Clinical importance of in vitro morphological subtypes

Epithelial ovarian cancer is a highly heterogeneous disease and remains the most lethal gynaecological malignancy in the Western world. Therapeutic approaches need to account for inter-patient and intra-tumoural heterogeneity and detailed characterization of in vitro models representing the different histological a

Ultimate Load of Different Types of Reinforced Self-Compacting Concrete Columns Attacked by Sulphate

In this study, the effects of the partial immersion of sulphate attack on the ultimate load capacity of reinforced self-compacting concrete (SCC) columns and the sulphate attack resistance improvement using silica fume, steel fibres, and the combination of silica fume and steel fibres were assessed. Twelve short circular self-compacting reinforced concrete columns (0.150 m in diameter and 0.7 m long) were cast and divided into groups according to (1) the three acid-attack groups. The first group was tested without an acid attack (control). The second group was tested after 1 month of exposure to 2% acid. The final group was tested after 1 month of exposure to 4% acid and was then (2) subdivided according to the type of casted concrete. The first group was cast with SCC. The second group was cast with SCC and silica fume (0.1% of the cement weight). The third group was cast with SCC and 1% volume fraction steel fibres. The fourth group was cast with SCC silica fume and 1% volume fraction steel fibre. All columns were tested by axial loading. The ultimate load was increased by 42% with silica fume, 190% with steel fibres, and 238% with silica fume and steel fibres. Exposure to 2% and 4% acid reduced the ultimate loads of the columns casted with SCC by 23% and 47%, the columns casted with SCC and silica fume by 34% and 37%, the columns casted with SCC and steel fibres by 69% and 78%, and the columns casted with SCC, silica fume, and steel fibres by 72% and 79%, respectively. Based on the results, using silica fumes improved sulphate resistance, and using steel fibres enhanced sulphate resistance at an acceptable ratio. Furthermore, the mix with silica fume and steel fibres improved sulphate resistance at a good ratio. We encountered several problems in this study. The partial immersion of sulphate affected the strain in both concrete and steel. Future studies using different immersion ratios are recommended. Doi: 10.28991/CEJ-2022-08-10-04 Full Text: PD