Sample-Efficient Learning of Mixtures

We consider PAC learning of probability distributions (a.k.a. density estimation), where we are given an i.i.d. sample generated from an unknown target distribution, and want to output a distribution that is close to the target in total variation distance. Let $\mathcal F$ be an arbitrary class of probability distributions, and let $\mathcal{F}^k$ denote the class of $k$-mixtures of elements of $\mathcal F$. Assuming the existence of a method for learning $\mathcal F$ with sample complexity $m_{\mathcal{F}}(\epsilon)$, we provide a method for learning $\mathcal F^k$ with sample complexity $O({k\log k \cdot m_{\mathcal F}(\epsilon) }/{\epsilon^{2}})$. Our mixture learning algorithm has the property that, if the $\mathcal F$-learner is proper/agnostic, then the $\mathcal F^k$-learner would be proper/agnostic as well. This general result enables us to improve the best known sample complexity upper bounds for a variety of important mixture classes. First, we show that the class of mixtures of $k$ axis-aligned Gaussians in $\mathbb{R}^d$ is PAC-learnable in the agnostic setting with $\widetilde{O}({kd}/{\epsilon ^ 4})$ samples, which is tight in $k$ and $d$ up to logarithmic factors. Second, we show that the class of mixtures of $k$ Gaussians in $\mathbb{R}^d$ is PAC-learnable in the agnostic setting with sample complexity $\widetilde{O}({kd^2}/{\epsilon ^ 4})$, which improves the previous known bounds of $\widetilde{O}({k^3d^2}/{\epsilon ^ 4})$ and $\widetilde{O}(k^4d^4/\epsilon ^ 2)$ in its dependence on $k$ and $d$. Finally, we show that the class of mixtures of $k$ log-concave distributions over $\mathbb{R}^d$ is PAC-learnable using $\widetilde{O}(d^{(d+5)/2}\epsilon^{-(d+9)/2}k)$ samples.Comment: A bug from the previous version, which appeared in AAAI 2018 proceedings, is fixed. 18 page

Alkaloid inspired spirocyclic oxindoles from 1,3-dipolar cycloaddition of pyridinium ylides

Cycloaddition reactions between pyridinium ylides and 3-alkenyl oxindoles that proceed in high yield and with very good regio- and diastereoselectivity are reported. The resulting cycloadducts have the same stereochemistry of biologically active oxindole alkaloids, such as strychnofoline

On-line monitoring of the crystallization process: relationship between crystal size and electrical impedance spectra

On-line monitoring of crystal size in the crystallization process is crucial to many pharmaceutical and fine-chemical industrial applications. In this paper, a novel method is proposed for the on-line monitoring of the cooling crystallization process of L-glutamic acid (LGA) using electrical impedance spectroscopy (EIS). The EIS method can be used to monitor the growth of crystal particles relying on the presence of an electrical double layer on the charged particle surface and the polarization of double layer under the excitation of alternating electrical field. The electrical impedance spectra and crystal size were measured on-line simultaneously by an impedance analyzer and focused beam reflectance measurement (FBRM), respectively. The impedance spectra were analyzed using the equivalent circuit model and the equivalent circuit elements in the model can be obtained by fitting the experimental data. Two equivalent circuit elements, including capacitance (C 2) and resistance (R 2) from the dielectric polarization of the LGA solution and crystal particle/solution interface, are in relation with the crystal size. The mathematical relationship between the crystal size and the equivalent circuit elements can be obtained by a non-linear fitting method. The function can be used to predict the change of crystal size during the crystallization process

Heritabilities, proportions of heritabilities explained by GWAS findings, and implications of cross-phenotype effects on PR interval

Electrocardiogram (ECG) measurements are a powerful tool for evaluating cardiac function and are widely used for the diagnosis and prediction of a variety of conditions, including myocardial infarction, cardiac arrhythmias, and sudden cardiac death. Recently, genome-wide association studies (GWASs) identified a large number of genes related to ECG parameter variability, specifically for the QT, QRS, and PR intervals. The aims of this study were to establish the heritability of ECG traits, including indices of left ventricular hypertrophy, and to directly assess the proportion of those heritabilities explained by GWAS variants. These analyses were conducted in a large, Dutch family-based cohort study, the Erasmus Rucphen Family study using variance component methods implemented in the SOLAR (Sequential Oligogenic Linkage Analysis Routines) software package. Heritability estimates ranged from 34 % for QRS and Cornell voltage product to 49 % for 12-lead sum. Trait-specific GWAS findings for each trait explained a fraction of their heritability (17 % for QRS, 4 % for QT, 2 % for PR, 3 % for Sokolow–Lyon index, and 4 % for 12-lead sum). The inclusion of all ECG-associated single nucleotide polymorphisms explained an additional 6 % of the heritability of PR. In conclusion, this study shows that, although GWAS explain a portion of ECG trait variability, a large amount of heritability remains to be explained. In addition, larger GWAS for PR are likely to detect loci already identified, particularly those observed for QRS and 12-lead sum

Влияние трансформационного лидерства на организационную и лидерскую эффективность: эмпирический пример Пакистана

Modern dynamic era and today’s cognizant society compels the new leaders to face real challenges for leaders around the globe; based on the strong ties of knowledge integration companies focus on nurturing innovation for survival and strive for improvements to compete and sustain in the market. However, organizations sometimes fail to achieve viable competitive advantage due to their limited understanding of the relationships amid these premeditated variables. This study investigates the impact of transformational leadership on organizational performance; employing organizational innovation as the mediating role. The study explores that the relationship between “transformational leadership” and “organizational performance” is convincing. “Convenience sampling techniques” are employed to gather information i.e. data is collected by using questionnaire employed to evaluate transformational leaders. Questionnaires consist of 25 question items have been distributed among multiple tier leaders working in MIA Group and is subsequently analyzed by using SPSS. The current research will assist the managers/leading role professionals to develop a required leadership style in one's organizations. Most of the organizations require an environment where employees are encouraged by motivated leaders and become more effective and creative in leading successful organizations. Further, it provides persuasive evidence for the significance of continuing the efforts to understand the nature of the leadership behaviors-effectiveness connection.La era dinámica moderna y la sociedad consciente de hoy obliga a los nuevos líderes a enfrentar desafíos reales para los líderes de todo el mundo; basadas en los fuertes lazos de integración de conocimiento, las empresas se centran en fomentar la innovación para la supervivencia y se esfuerzan por mejorar para competir y mantenerse en el mercado. Sin embargo, las organizaciones a veces no logran una ventaja competitiva viable debido a su comprensión limitada de las relaciones en medio de estas variables premeditadas. Este estudio investiga el impacto del liderazgo transformacional en el desempeño organizacional; Empleando la innovación organizativa como el papel mediador. El estudio explora que la relación entre "liderazgo transformacional" y "desempeño organizacional" es convincente. Las "técnicas de muestreo de conveniencia" se emplean para recopilar información, es decir, los datos se recopilan mediante el cuestionario empleado para evaluar a los líderes transformacionales. Los cuestionarios consisten en 25 preguntas que se han distribuido entre líderes de múltiples niveles que trabajan en el Grupo MIA y se analizan posteriormente mediante el uso de SPSS. La investigación actual ayudará a los gerentes / profesionales de rol líder a desarrollar un estilo de liderazgo requerido en las organizaciones de uno. La mayoría de las organizaciones requieren un entorno donde los empleados estén motivados por líderes motivados y sean más efectivos y creativos para liderar organizaciones exitosas. Además, proporciona evidencia persuasiva de la importancia de continuar los esfuerzos para comprender la naturaleza de la conexión entre el comportamiento y la eficacia del liderazgo.Современная динамичная эпоха и современное сознательное общество заставляют новых лидеров сталкиваться с реальными проблемами для лидеров во всем мире; Основываясь на прочных связях в области интеграции знаний, компании сосредоточены на развитии инноваций для выживания и стремятся к улучшениям, чтобы конкурировать и поддерживать на рынке. Однако организациям иногда не удается добиться жизнеспособного конкурентного преимущества из-за их ограниченного понимания взаимоотношений среди этих преднамеренных переменных. Это исследование исследует влияние трансформационного лидерства на организационные показатели; использование организационных инноваций в качестве посреднической роли. В исследовании исследуется, что связь между «трансформационным лидерством» и «эффективностью организации» является убедительной. «Удобные методы выборки» используются для сбора информации, то есть данные собираются с использованием вопросника, используемого для оценки лидеров трансформации. Анкеты состоят из 25 вопросов, которые были распределены среди лидеров нескольких уровней, работающих в MIA Group, и впоследствии анализируются с использованием SPSS. Текущее исследование поможет менеджерам / ведущим специалистам по ролям выработать необходимый стиль руководства в своих организациях. Большинству организаций требуется среда, в которой мотивированные лидеры поощряют сотрудников и становятся более эффективными и креативными в ведущих успешных организациях. Кроме того, он предоставляет убедительные доказательства значимости продолжения усилий по пониманию природы связи между поведением и эффективностью руководства

ALLOCATIVE EFFICIENCY OF RESOURCE UTILIZATION IN FISH FARMING IN OWO LOCAL GOVERNMENT AREA OF ONDO STATE, NIGERIA.

 Objective: The study assessed resource-use efficiency among fish farmers in Owo Local Government Area of Ondo State, Nigeria.Methods: A multi stage sampling technique was used to select 50 fish farmers for the study. Data were collected during 2013 production cycle. Multiple regression analysis was used to determine the effects of variables determining the quantity of fish harvested. Allocative efficiency of resources used in raising fish was determined using marginal value product and marginal factor cost.Results: Significant determinants of the quantity of fish harvested at the end of the production cycle were fish seeds (0.647) and the quantity of feeds used (0.339). The two productive resources were significant at 0.01 probability level. The values of allocative efficiency of all the inputs used indicated that pond size (7.041) and fish seeds (11.500) were under-utilized while labour (0.705) was over-utilized; only feeds (1.032) were optimally utilized during fish production process.Conclusion: Under-utilized resources should be optimally used in order to obtain the best possible output. Excessive use of labour should be reduced so as to cut cost of production and increase profit margin. It is also recommended that fish farmer's capacity should be developed through regular training on how to allocate productive resources efficiently

DRIVERS OF EMPLOYEE ENGAGEMENT AND ROLE OF TRANSACTIONAL LEADERSHIP-CASE OF PAKISTANI BANKING SECTOR

The purpose of the article: This research explored and contributes to the leadership literature by investigating the influence of transactional leadership over employee engagement at certain banks located in KPK and Punjab province of Pakistan. It observes the influence of main aspects i-e contingent reward, active management by exception (MBE active) on worker’s regular job commitmentMaterials and methods: This distinctive combination of leadership behaviors are compared with attention given specifically to everyday work settings. Twenty banks are selected involving 180 employees. Questionnaires and interviews are conducted to collect data.Results of the research: The relationships among variables are examined through the Spearman Rank-order correlation coefficient.  The moderating effects associated with corporate culture are observed by employing multiple regression analyses. A positive and significant relationship is revealed between transactional management and chosen variables except “passive management by exemption”. It is safely predicted that employee job satisfaction can be greatly elevated through transactional leadership. It is established that “contingent reward” and “active management by exemption” improve worker's engagement in contrast to passive management by exemption. Applications: This research can be used for universities, teachers, and students. Novelty/Originality: In this research, the model of Drivers of Employee Engagement and Role of Transactional Leadership-Case of Pakistani Banking Sector is presented in a comprehensive and complete manner

Meta-analysis of genome-wide association studies from the CHARGE consortium identifies common variants associated with carotid intima media thickness and plaque

Carotid intima media thickness (cIMT) and plaque determined by ultrasonography are established measures of subclinical atherosclerosis that each predicts future cardiovascular disease events. We conducted a meta-analysis of genome-wide association data in 31,211 participants of European ancestry from nine large studies in the setting of the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) Consortium. We then sought additional evidence to support our findings among 11,273 individuals using data from seven additional studies. In the combined meta-analysis, we identified three genomic regions associated with common carotid intima media thickness and two different regions associated with the presence of carotid plaque (P < 5 × 10 -8). The associated SNPs mapped in or near genes related to cellular signaling, lipid metabolism and blood pressure homeostasis, and two of the regions were associated with coronary artery disease (P < 0.006) in the Coronary Artery Disease Genome-Wide Replication and Meta-Analysis (CARDIoGRAM) consortium. Our findings may provide new insight into pathways leading to subclinical atherosclerosis and subsequent cardiovascular events