ROBUST LOW-RANK MATRIX FACTORIZATION WITH MISSING DATA BY MINIMIZING L1 LOSS APPLIED TO COLLABORATIVE FILTERING

In this age of information overload and plethora of choices, people increasingly rely on automatic recommender systems to tell them what suits their needs. A very effective approach for creating recommender systems is collaborative filtering, which is the task of predicting the preference/rating that a user would assign to an item based on preference data of that user and preference data of other users. One way to conduct collaborative filtering is through dimensionality reduction. The underlying concept of the approach lies in the belief that there are only a few features (reduced dimensions) that influence the user’s choice. In this paper we use low rank matrix factorization for dimensionality reduction. Singular Value Decomposition (SVD), which is minimizing the L2 norm is the most popular technique to perform matrix factorization. However, in most recommendation system data sets, often the users only rate a small amount of items, which creates missing data. As a result SVD fails. In recent years L1 norm has gained much importance and popularity because it is robust to outliers and missing data. In this thesis we use alternate convex optimization to perform L1 norm minimization to solve the matrix factorization problem and apply it to collaborative filtering. We also review some of the major challenges that collaborative filtering faces today and some of the other techniques used. Additionally, this thesis discusses the importance and future of collaborative filtering in medical applications that concerns the database of patient history (prescriptions/symptoms) and how it can be used as a predictive task for the future of the patient

Solution of a Mathematical Model Describing the Change of Hormone Level in Thyroid Using the Laplace Transform

In the present paper, a mathematical model describing the thyroid-pituitary homeostatic mechanism is analyzed for its physiological and clinical significance. The influence of different parameters on the stability behavior of the system is discussed. We have assumed in the present paper that the rate of thyrotropin production is reduced by an amount which is proportional to the blood concentration of thyroxine and also the rate of loss of thyrotropin is proportional to the existing thyrotropin concentration. The stability behavior of the system is analyzed and the possibility of occurrence of periodic solutions is looked into. As the pituitary gland can produce no output in the presence of thyroxine concentration greater than a certain value, we have also included a degenerate form of the equation for thyrotropin production in the present paper. The solutions of the system of governing equations are obtained by applying the Laplace transform. Also, the nature of the solution is interpreted graphically using the Maple12 technique for both stable and unstable behavior

A novel approach of developing micro crystalline cellulose reinforced cementitious composites with enhanced microstructure and mechanical performance

This paper reports a novel approach of preparing aqueous suspensions of microcrystalline cellulose (MCC) for fabrication of cementitious composites. MCC was dispersed homogeneously in water using Pluronic F-127 as a surfactant with the help of ultrasonication process and the aqueous suspensions were added to cement/sand mixture to prepare cementitious composites. A commonly used stabilizing agent for MCC, carboxy methyl cellulose (CMC) was also used for the comparison purpose. The prepared suspensions were characterized through visual inspection, UV-Vis spectroscopy and optical microscopy. The developed composites were characterized for their bulk density, flexural and compressive properties as well as microstructure. The influence of Pluronic and CMC concentration, superplasticizer, dispersion technique and dispersion temperature on mortar's mechanical performance was thoroughly studied to find out the optimum conditions. Overall, Pluronic (with Pluronic: MCC ratio of 1:5) led to better MCC dispersion as well as dispersion stability as compared to CMC. The best mechanical performance was achieved with Pluronic in combination with superplasticizer using ultrasonication process, resulting in improvement of 106%, 31% and 66% in flexural modulus, flexural strength and compressive strengths, respectively (highest values reported till date). The bulk density and hydration of cementitious composites also improved significantly with the addition of MCC.The authors acknowledge the Portuguese Fundação para a Ciência e a Technologia (FCT) for financial support through project PEst-C/CTM/LA0025/2013 (Strategic Project - LA 25 - 2013-2014). The authors also acknowledge the financial support from Portuguese National Funding, through, on the framework of project UID/CTM/00264/2013 and national funds through FCT, I.P., within the research unit C-MADE, Centre of Materials and Building Technologies (CIVE-Centro-Covilhã-4082), Universidade da Beira Interior, Portugal.info:eu-repo/semantics/publishedVersio

Maternal and perinatal outcome in abruption placenta in tertiary care center: a record based case series study

Background: Abruptio placenta is premature separation of the normally implanted placenta before delivery. It is one of the leading causes of maternal morbidity and neonatal morbidity and mortality, more so because of the difficulty to predict the acute event. It occurs in approximately one in 80 deliveries and remains a significant cause of perinatal mortality and morbidity. Objective of the study was to study maternal and perinatal outcome in cases of abruption. Methods: 42 cases of pregnant women who presented with abruption placenta to HSK hospital and Research Centre, S. Nijalingappa Medical College, a tertiary care centre at Bagalkot, from January 2022 to December 2022. Maternal and perinatal characteristics were retrieved from the case papers. Results: Among 42 cases of abruption 70% delivered vaginally and 30% underwent caesarean section. 84% had preterm delivery. 66% were still born. 21% were case of severe anaemia and required blood transfusion. 1 had maternal mortality. Conclusions: The availability of advanced emergency obstetric care across greater number of referral hospitals has been responsible for decreasing the morbidity and mortality associated with many obstetric conditions. However, the challenge with abruptio placenta is the difficulty of predicting this condition, and hence appropriate management. As of now, early referral to tertiary care centres, better availability of blood and blood products and early interventions have the potential to limit adverse maternal and perinatal outcomes. Research regarding predictors of placental abruption can help in improving maternal and perinatal outcome.

Preparation and Characterization of Various Interstitial N-Doped TiO2 Catalysts from Different Nitrogen Dopants for the Treatment of Polluted Water

In this work N-doped TiO2 nano particle photocatalysts were prepared through a sol-gel procedure using three different types of nitrogen dopants urea, diethanolamine (DEA) and triethylamine (TEN). Multiple techniques (XRD, TEM, SEM, EDX, BET, Raman and UV-Visible absorption) were commanded to characterize the crystal structure of N-doped TiO2. The catalytic activity of the N-doped TiO2 under ultraviolet (UV) and visible light irradiation is evidenced by the decomposition of 2-chlorophenol, showing that nitrogen atoms in the N-doped TiO2 are responsible for the visible light catalytic activity. It is suggested that doped nitrogen here is located at the interstitial site of TiO2 lattice. Amongst investigated nitrogen precursors diethanolamine provided the highest visible light absorption ability of interstitial N-doped TiO2 with the smallest energy band gap and the smallest anatase crystal size, resulting in the highest efficiency in 2-cholorophenol degradation. The photocatalytic activity and 2-CP mineralization ability of all N-doped TiO2 can be arranged in the following order:  TiO2/DEA > TiO2/TEN > TiO2/UREA > un-doped TiO2. Keywords: 2-chlorophenol, Photocatalytic degradation, N-doped TiO2, Different Nitrogen Dopants, urea, diethanolamine (DEA), triethylamine (TEN) and Catalytic Activity

Intergenerational effects of ocean temperature variation: Early life benefits are short-lived in threespine stickleback

Current climate change models predict an increase in temperature variability and extreme events such as heatwaves, and organisms need to cope with consequent changes to environmental variation. Non-genetic inheritance mechanisms can enable parental generations to prime their offspring’s abilities to acclimate to environmental change–but they may also be deleterious. When parents are exposed to predictable environments, intergenerational plasticity can lead to better offspring trait performance in matching environments. Alternatively, parents exposed to variable or unpredictable environments may use plastic bet-hedging strategies to adjust the phenotypic variance among offspring. Here, we used a model species, the threespine stickleback (Gasterosteus aculeatus), to test whether putatively adaptive intergenerational effects can occur in response to shifts in environmental variation as well as to shifts in environmental mean, and whether parents employ plastic bet-hedging strategies in response to increasing environmental variation. We used a full-factorial, split-clutch experiment with parents and offspring exposed to three temperature regimes: constant, natural variation, and increased variation. We show that within-generation exposure to increased temperature variation reduces growth of offspring, but having parents that were exposed to natural temperature variation during gametogenesis may offset some early-life negative growth effects. However, these mitigating intergenerational effects do not appear to persist later in life. We found no indication that stickleback mothers plastically altered offspring phenotypic variance (egg size or clutch size) in response to temperature variation. However, lower inter-individual variance of juvenile fish morphology in offspring of increased variation parents may imply the presence of conservative bet-hedging strategies in natural populations. Overall, in our experiment, parental exposure to temperature variation had limited effects on offspring fitness-related traits. Natural levels of environmental variation promoted a potentially adaptive intergenerational response in early life development, but under more challenging conditions associated with increased environmental variation, the effect was lost.</jats:p

A comparison of low intensity UV-C and high intensity pulsed polychromatic sources as elicitors of hormesis in tomato fruit

Post-harvest hormetic treatment of mature green tomato fruit (Solanum lycopersicum cv. Mecano) with high intensity pulsed polychromatic light (HIPPL) significantly delayed ripening to levels comparable to those achieved using a conventional low intensity UV-C (LIUV) source. A 16 pulse HIPPL treatment reduced the ΔTCI (tomato colour index) by 50.1 % whilst treatment with a LIUV source led to a reduction of 43.1 %. Moreover, the 16 pulse treatment also induced disease resistance in the fruit to Botrytis cinerea with a 41.7 % reduction in disease progression compared to a 38.1 % reduction for the LIUV source. A single 16 pulse HIPPL treatment was found to significantly reduce disease progression on both mature green and ripe fruit with a 28.5 % reduction on ripe fruit in comparison to 13.4 % for the LIUV treatment. It is shown here that delayed ripening and disease resistance are local responses in side treated tomato fruit for both LIUV and HIPPL treatments. Finally, utilising a 16 pulse HIPPL treatment would reduce treatment times from 370 s for LIUV sources to 10 s per fruit - a 97.3 % reduction

Comparison of theoretical and practical performances with 802.11N and 802.11Ac wireless networking

This work explores the theoretical and practical performances of the two most recent IEEE standards, 802.11n and 802.11ac. Experiments were conducted to measure data rates to characterize performance effects of distance and interference between different channels. We conclude that the majority of test cases show 802.11ac achieved higher data rates than its predecessor, as expected. However, performance of 802.11ac decreased at a significantly faster rate with increasing distance from client to AP when compared to the decreasing performance experienced with 802.11n. Furthermore, 802.11n consistently achieved real data rates much closer to the theoretical data rate than did 802.11ac

A Compact Lowpass Filter with Ultra Wide Stopband using Stepped Impedance Resonator

In this paper, a compact asymmetric-shaped microstrip lowpass filter (LPF) using a stepped impedance resonator is presented. An ultra wide stopband with high attenuation in the stopband region, within very small circuit area is achieved for the proposed filter using novel asymmetric structures for resonator and suppressor. The transmission zeros of the resonators can be adjusted as a function of high impedance and low impedance microstrip lines, and due to the asymmetric structure, the proposed suppressing cell can be located within the resonator structure without occupying a large area. For verification, a 2.92 GHz LPF is designed and fabricated. The experimental results, in comparison with the other LPFs, show that the proposed LPF has significant advantages in the stopband characteristics with acceptable sharp roll off. The measured passband insertion loss is below 0.1 dB, and the rejection band over -20 dB is obtained from 3.42 GHz to 36.2 GHz. The size of filter corresponds to compact electrical size of 0.156 λg × 0.128 λg, where λg is the guided wavelength at 2.92 GHz. Also, the maximum variation of the group delay in 80 percent of the passband region is only about 0.2 ns