E-commerce Recommendation by an Ensemble of Purchase Matrices with Sequential Patterns

In E-commerce recommendation systems, integrating collaborative filtering (CF) and sequential pattern mining (SPM) of purchase history data will improve the accuracy of recommendations and mitigate limitations of using only explicit user ratings for recommendations. Existing E-commerce recommendation systems which have combined CF with some form of sequences from purchase history are those referred to as LiuRec09, ChioRec12, and HPCRec18. ChoiRec12 system, HOPE first derives implicit ratings from purchase frequency of users in transaction data which it uses to create user item rating matrix input to CF. Then, it computes the CFPP, the CF-based predicted preference of each target user_u on an item_i as its output from the CF process. Similarly, it derives sequential patterns from the historical purchase database from which it obtains the second output matrix of SPAPP, sequential pattern analysis predicted preference of each user for each item. The final predicted preference of each user for each item FPP is obtained by integrating these two matrices by giving 90\% to SPAPP and 10\% to CFPP so it can recommend items with highest ratings to users. A limitation of HOPE system is that in user item matrix of CF, it does not distinguish between purchase frequency and ratings used for CF. Also in SPM, it recommends items, regardless of whether user has purchased that item before or not. This thesis proposes an E-commerce recommendation system, SEERs (Stacking Ensemble E-commerce Recommendation system), which improves on HOPE system to make better recommendations in the following two ways: i) Learning the best minimum support for SPA, best k similar users for CF and the best weights for integrating the four used matrices. ii) Separating their two intermediate matrices of CFPP and SPAPP into four intermediate matrices of CF not purchased, SPM purchased, SPM not purchased and purchase history matrix which are obtained and merged with the better-learned parameters from (i) above. Experimental results show that by using best weights discovered in training phase, and also separating purchased and not purchased items in CF and sequential pattern mining methods, SEERS provides better precision, recall, F1 score, and accuracy compared to tested systems

Extended Bandwidth Doherty Power Amplifier for Carrier Aggregated Signals

In the conventional classes of power amplifiers the efficiency drops at power back-off, whereas in order to maximize the spectral efficiency and data rate, wireless communication standards employ signals with high peak to average power ratio. This results in low average efficiency for power amplifiers, which in turn results in heavy cooling requirements and damage to the environment. To improve the low back-off efficiency Doherty technique has been widely investigated. But, the conventional Doherty power amplifiers are fairly narrowband, while modern transmitters are needed to support multiple standards and operate at multiple frequency bands. This thesis proposes two novel output combiners for Doherty power amplifiers with extended bandwidth. It will be shown analytically how the problem of wideband Doherty can be converted into an impedance synthesization problem. Then two networks to synthesize the desired impedance are proposed. To achieve the proper load modulation over a wide bandwidth, the first proposed combiner employs a quarter-wave short-circuited stub at the output of the peaking transistor and the second proposed combiner uses a parallel LC tank at the same node. In addition to inherent wideband characteristics, the proposed Doherty output combiners have three other important benefits. First, they present small low-frequency impedance for both the main and peaking transistors, which results in improved linearity and linearizability when the amplifier is concurrently driven with multi-band modulated signals. Second, the new combiners result in smaller group delay variation across the band compared to the conventional Doherty amplifier, which results in improved linearizability when the amplifier is driven with extra wideband modulated signals. Finally, the output capacitance of the peaking transistor can be easily absorbed into the combiners without compromising the performance of the amplifier. The thesis starts with an overview of the Doherty power amplifier principles and provides a bandwidth analysis for the conventional Doherty power amplifier. Then it continues with the new approach to extend the bandwidth of Doherty amplifiers with respect to requirements of multi-band transmission. Based on the proposed combiners, two Gallium Nitride 20 W Doherty power amplifiers have been designed and fabricated. The measurement results have been provided to validate the developed theory. The first amplifier covers 1.72 to 2.27 GHz and the second one covers 700 to 950 MHz and both maintain higher than 48 % of drain efficiency at 6 dB back-off across the band. The two amplifiers are successfully linearized when driven with carrier aggregated modulated signals

Population density and spatial distribution pattern of Hypera postica (Coleoptera: Curculionidae) in Ardabil, Iran

The alfalfa weevil, Hypera postica (Gyllenhal), feeds almost exclusively on alfalfa, Medicago saliva L. in most region of the world where forage crop is grown. It has been investigated the population density and spatial distribution of alfalfa weevil on alfalfa in Ardabil during 2010. Using a 0.25 m(2) quadrate sample unit a reliable sample size was 65, with maximum relative variation of 15%. The relative variation (RV) of the primary sampling data was 13.6. The highest population density of the alfalfa weevil was recorded on 17(th) April. To estimate the spatial distribution pattern of this pest, data were analyzed through index of dispersion. Lloyd's mean crowding. Morisita's index and two regression models (Taylor's Power Law and Iwao's Patchiness Regression). Taylor's model showed an aggregated distribution pattern for all life stages. Iwao's patchiness regression indicated that larvae, adult and total life cycle had aggregated spatial distribution (t(c

The Efficacy of Intramuscular Calcitonin Injection in the Management of Lumbar Spinal Stenosis

Study DesignA prospective, cross-sectional, non-randomized study.PurposeTo assess the effectiveness of intramuscular calcitonin injection in the treatment of lumbar spinal stenosis (LSS).Overview of LiteratureLSS, manifesting as chronic low back pain and neurogenic claudication, is a chronic condition with an increasing incidence in the elderly population having inadequate effective conservative treatment options.MethodsIn this study, 36 patients with LSS who were diagnosed based on the clinical findings and magnetic resonance imaging were included. Patients received 100 IU of calcitonin per week for one month and were evaluated before and after treatment using the Oswestry disability index (ODI) questionnaire and visual analogue scale (VAS). Before treatment, the patients were divided into two subgroups based on their ODI results: patients with mild to moderate low back pain (disability, 0%-40%) and patients with severe or very severe low back pain (disability, 40%-100%).ResultsIn patients with mild to moderate low back pain, there were no significant changes in the ODI and VAS after calcitonin injection. But in patients with severe or very severe low back pain, pain severity, personal functions, ability to lift and carry objects, time interval between standing and initiation of pain, social life, disability percentage, and VAS were significantly improved after treatment with calcitonin.ConclusionsIt seems that an intramuscular injection of low dose of calcitonin may have some beneficial effects on the pain due to LSS, especially in patients who suffer from severe or very severe low back pain

Laboratory toxicity and field efficacy of Lufenuron, Dinotefuran and Thiamethoxam against Hypera postica (Gyllenhal, 1813) (Coleoptera: Curculionidae)

Toxicity of the insect growth regulator lufenuron and two neonicotinoids, dinotefuran and thiamethoxam, for the alfalfa weevil, Hypera postica (Gyllenhal, 1813), was determined through exposure of the second instar larvae and adults to dipped alfalfa leaves under laboratory conditions at 25±1 °C, 60±5% RH ,16:8 L:D. Based on mode of action, the mortality of the treated larvae and adults was recorded after 72 hours for lufenuron, and after 24 hours for dinotefuran and thiamethoxam. LC50 values for second instar larvae were 34.32, 24.91.32.9, 15.82 AI L-1 and for adults were 175.67, 289.76, 164.02 AI L-1 for dinotefuran, thiamethoxam and lufenuran, respectively. Results showed that lufenuron was the most toxic to both larvae and adults of H. postica among insecticides tested. Once the height of alfalfa field reached to about 20 cm, a single treatment was made on May 11th. All insecticides reduced the mean number of alfalfa weevil. According to results of laboratory and field experiments, lufenuron might be a more valuable chemical to adequately control H. postica with little adverse effects on environment. lufenuron may be considered as alternative chemicals to other compounds with a high potential for controlling certain pests and with less adverse effects on natural enemies

Global Air Quality and COVID-19 Pandemic : Do We Breathe Cleaner Air?

The global spread of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has challenged most countries worldwide. It was quickly recognized that reduced activities (lockdowns) during the Coronavirus Disease of 2019 (COVID-19) pandemic produced major changes in air quality. Our objective was to assess the impacts of COVID-19 lockdowns on groundlevel PM2.5, NO2, and O-3 concentrations on a global scale. We obtained data from 34 countries, 141 cities, and 458 air monitoring stations on 5 continents (few data from Africa). On a global average basis, a 34.0% reduction in NO2 concentration and a 15.0% reduction in PM2.5 were estimated during the strict lockdown period (until April 30, 2020). Global average O-3 concentration increased by 86.0% during this same period. Individual country and continent-wise comparisons have been made between lockdown and business-as-usual periods. Universally, NO2 was the pollutant most affected by the COVID-19 pandemic. These effects were likely because its emissions were from sources that were typically restricted (i.e., surface traffic and non-essential industries) by the lockdowns and its short lifetime in the atmosphere. Our results indicate that lockdown measures and resulting reduced emissions reduced exposure to most harmful pollutants and could provide global-scale health benefits. However, the increased O-3 may have substantially reduced those benefits and more detailed health assessments are required to accurately quantify the health gains. At the same, these restrictions were obtained at substantial economic costs and with other health issues (depression, suicide, spousal abuse, drug overdoses, etc.). Thus, any similar reductions in air pollution would need to be obtained without these extensive economic and other consequences produced by the imposed activity reductions.Peer reviewe

Genetic determinants of telomere length from 109,122 ancestrally diverse whole-genome sequences in TOPMed

Genetic studies on telomere length are important for understanding age-related diseases. Prior GWAS for leukocyte TL have been limited to European and Asian populations. Here, we report the first sequencing-based association study for TL across ancestrally-diverse individuals (European, African, Asian and Hispanic/Latino) from the NHLBI Trans-Omics for Precision Medicine (TOPMed) program. We used whole genome sequencing (WGS) of whole blood for variant genotype calling and the bioinformatic estimation of telomere length in n=109,122 individuals. We identified 59 sentinel variants (p-value OBFC1indicated the independent signals colocalized with cell-type specific eQTLs for OBFC1 (STN1). Using a multi-variant gene-based approach, we identified two genes newly implicated in telomere length, DCLRE1B (SNM1B) and PARN. In PheWAS, we demonstrated our TL polygenic trait scores (PTS) were associated with increased risk of cancer-related phenotypes

Measurement of t(t)over-bar normalised multi-differential cross sections in pp collisions at root s=13 TeV, and simultaneous determination of the strong coupling strength, top quark pole mass, and parton distribution functions

Peer reviewe

Measurement of the top quark forward-backward production asymmetry and the anomalous chromoelectric and chromomagnetic moments in pp collisions at √s = 13 TeV

Abstract The parton-level top quark (t) forward-backward asymmetry and the anomalous chromoelectric (d̂ t) and chromomagnetic (μ̂ t) moments have been measured using LHC pp collisions at a center-of-mass energy of 13 TeV, collected in the CMS detector in a data sample corresponding to an integrated luminosity of 35.9 fb−1. The linearized variable AFB(1) is used to approximate the asymmetry. Candidate t t ¯ events decaying to a muon or electron and jets in final states with low and high Lorentz boosts are selected and reconstructed using a fit of the kinematic distributions of the decay products to those expected for t t ¯ final states. The values found for the parameters are AFB(1)=0.048−0.087+0.095(stat)−0.029+0.020(syst),μ̂t=−0.024−0.009+0.013(stat)−0.011+0.016(syst), and a limit is placed on the magnitude of | d̂ t| < 0.03 at 95% confidence level. [Figure not available: see fulltext.