A study on the effect of free cash flow and profitability current ratio on dividend payout ratio: Evidence from Tehran Stock Exchange

Decision making about dividend payout is one of the most important decision that companies should encounter. Identifying factors that influence dividends can help managers in making an appropriate dividend policy. In the other side, companies’ dividend payouts over time and with a stable manner may influence on stock price, future earnings growth and finally investor's evaluation about owners' equity. Hence, investigating the factors influencing dividend payout ratio is of high importance. In this research, we investigate the effects of various factors on dividend payout ratio of Tehran Stock Exchange (TSE) listed companies. We use time series regression (panel data) in order to test the hypothesis of this study. This study provides empirical evidences by choosing a sample of 102 companies over the time span of 2005-2010. The result shows that independent variables of free cash flow and profitability current ratio have negative and significant impact on dividend payout ratio; whereas, the independent variable of leverage ratio has a positive and significant impact on dividend payout ratio. The other independent ratio such as size of the company, growth opportunities and systematic risk do not have any significant influence on dividend payout ratio

Use of the energy of parametric oscillations to improve drilling indices

Purpose. Increase of the efficiency of using energy of parametric oscillations within the assembly of drilling string bottom by means of solving nonlinear-parametric equations of a “bit – drive motor – drilled-out rock” system to improve drilling indices. Methods. The paper applies the method of mathematical modeling of a mechanical system as well as impedance method to study oscillations. While modeling the system, a bit is considered to be an absolutely solid body; elastic elements are non-inertial, drive motor is ideal, and resistance in elastic relations is viscous. While modeling dynamic parameters of a drill string and its interaction with a near-bit system and bottom hole, mechanical system is represented in the form of blocks interacting with each other. Drill string in models is a sequential system of uniform rods. Findings. In the course of analytical studies, it has been proved that use of energy of parametric oscillations within the assembly of drilling string bottom makes it possible to increase axial load on a bit as well as rise mechanical velocity especially while drilling horizontal areas of inclined boreholes. Dynamic parameters of mechanical system of a drill string and its interaction with near-bit system and bottom hole have been substantiated. It has been determined that limitation of the amplitude of resonant vertical oscillations for a bit is possible at the expense of toothed surface of cone rollers in terms of periodical positioning from one tooth to two teeth, physical and mechanical pro-perties of the drilled-out rocks, and features of correcting elements mounted above the bit. Originality. Innovative mathematical model describing dynamics of the operation of a “bit – drive motor – drilled-out rock” mechanical system has been developed taking into consideration the effect of parametric oscillations. Practical implications. Limited amplitude of resonant vertical oscillations of a bit is the condition of efficient assembly operation and long service life of its components in the context of parametric excitations. The obtained results may be useful while designing drill rigs.Мета. Підвищення ефективності використання енергії параметричних коливань у компоновці низу бурильної колони шляхом розв’язання нелінійно-параметричних рівнянь системи “долото – приводний двигун – розбурювана порода” для підвищення показників буріння. Методика. В роботі використано метод математичного моделювання механічної системи та імпедансний метод дослідження коливань. При моделюванні системи долото вважається абсолютно твердим тілом, пружні елементи – безінерційними, приводний двигун – ідеальним, а опір у пружних зв’язках – в’язким. При дослідженні динамічних параметрів бурильної колони та її взаємодії з наддолотною системою і вибоєм механічна система представлена у вигляді блоків, які взаємодіють поміж собою. Бурильна колона в моделях становить послідовну систему однорідних стрижнів. Результати. В ході аналітичних досліджень було доведено, що використання енергії параметричних коливань у компоновці низу бурильної колони дає можливість збільшити осьове навантаження на долото та підвищити механічну швидкість, особливо під час буріння горизонтальної частини похило спрямованих свердловин. Обґрунтовано динамічні параметри механічної системи бурильної колони та її взаємодії з наддолотною системою і вибоєм. Виявлено, що обмеження амплітуди резонансних вертикальних коливань досягається долотом за рахунок зубчатої поверхні шарошок при періодичному переступанні з одного зуба на два, фізико-механічних властивостей розбурюваних порід і властивостей коректуючих елементів, встановлених над долотом. Наукова новизна. Розроблено нову математичну модель, що описує динаміку роботи механічної системи “долото – приводний двигун – розбурювана порода” з урахуванням впливу параметричних коливань. Практична значимість. Наявність обмеження амплітуди резонансних вертикальних коливань долота створює умови працездатності компоновок і довговічності її елементів із параметричними коливаннями. Отримані результати можуть бути корисними при проектуванні бурових конструкцій.Цель. Повышение эффективности использования энергии параметрических колебаний в компоновке низа бурильной колонны путем решения нелинейно-параметрических уравнений системы “долото – приводной двигатель – разбуриваемая порода” для повышения показателей бурения. Методика. В работе использован метод математического моделирования механической системы и импедансный метод исследования колебаний. При моделировании системы долото считается абсолютно твердым телом, упругие элементы – безинерционными, приводной двигатель – идеальным, а сопротивление в упругих связях – вязким. При исследовании динамических параметров бурильной колонны и ее взаимодействия с наддолотной системой и забоем механическая система представлена в виде блоков, которые взаимодействуют между собой. Бурильная колонна в моделях составляет последовательную систему однородных стержней. Результаты. В ходе аналитических исследований было доказано, что использование энергии параметрических колебаний в компоновке низа бурильной колонны позволяет увеличить осевую нагрузку на долото и повысить механическую скорость, особенно при бурении горизонтальной части наклонно-направленных скважин. Обоснованы динамические параметры механической системы бурильной колонны и ее взаимодействия с наддолотной системой и забоем. Выявлено, что ограничения амплитуды резонансных вертикальных колебаний достигается долотом за счет зубчатой поверхности шарошек при периодическом перешагивании с одного зуба на два, физико-механических свойств разбуриваемых пород и свойств корректирующих элементов, установленных над долотом. Научная новизна. Разработано новую математическую модель, описывающую динамику работы механической системы “долото – приводной двигатель – разбуриваемая порода” с учетом влияния параметрических колебаний. Практическая значимость. Наличие ограничения амплитуды резонансных вертикальных колебаний долота создает условия работоспособности компоновок и долговечности ее элементов с параметрическими колебаниями. Полученные результаты могут быть полезными при проектировании буровых конструкций.The results of the study were obtained without any support from any project or financing

Attenuation of serum laminin concentrations upon treatment of chronic hepatitis

Objectives: The aim of this work was to determine the serum laminin level cutoff point for predicting liver fibrosis highlighting its diagnostic value and determining the effect of treatment on serum laminin concentrations. Methods: Serum laminin concentrations in chronic hepatitis patients (n=62) and controls (n=20) were compared by ELISA and stages of fibrosis were assessed according to the modified Knodell score system. Results: Mean serum laminin concentration in patients (91.9 ± 20.9 ng/ml) was greater than controls (46.2 ± 10.2 ng/ml; p <0.001). Serum concentrations of laminin in all stages of hepatic fibrosis were significantly higher than those of healthy controls (p <0.05). A cutoff point of 52ng laminin/ml of serum was obtained for the discrimination of various stages of liver fibrosis showing a good sensitivity (96.8%) and specificity (80%). After 6 months of treatment, a gradual decrease in serum laminin concentrations were observed, however the level was still higher than that of the healthy group (p<0.05). Conclusions: Our findings suggest that the serum laminin concentration is a useful noninvasive marker of liver fibrosis and shows a strong positive correlation with different stages of the disease

A Concurrent Tuple Set Architecture for Call Level Interfaces

Call Level Interfaces (CLI) are low level API aimed at providing services to connect two main components in database applications: client applications and relational databases. Among their functionalities, the ability to manage data retrieved from databases is emphasized. The retrieved data is kept in local memory structures that may be permanently connected to the host database. Client applications, beyond the ability to read their contents, may also execute Insert, Update and Delete actions over the local memory structures, following specific protocols. These protocols are row (tuple) oriented and, while being executed, cannot be preempted to start another protocol. This restriction leads to several difficulties when applications need to deal with several tuples at a time. The most paradigmatic case is the impossibility to cope with concurrent environments where several threads need to access to the same local memory structure instance, each one pointing to a different tuple and executing its particular protocol. To overcome the aforementioned fragility, a Concurrent Tuple Set Architecture (CTSA) is proposed to manage local memory structures. A performance assessment of a Java component based on JDBC (CLI) is also carried out and compared with a common approach. The main outcome of this research is the evidence that in concurrent environments, components relying on the CTSA may significantly improve the overall performance when compared with solutions based on standard JDBC API.(undefined

Serum hyaluronic acid and laminin as potential tumor markers for upper gastrointestinal cancers

Background: Early diagnosis of patients with upper gastrointestinal cancer is important because many cases are diagnosed in advanced stages and have poor prognosis. Several studies have reported increased serum levels of hyaluronic acid and laminin in various cancers and the correlation of the levels with poor prognosis. However, little data on the use of serum hyaluronic acid and laminin levels for early detection of esophageal and gastric cancers are available. Methods: We assessed serum hyaluronic acid and laminin levels using enzyme-linked immunosorbent assay in 20 gastric cardia cancer, 23 gastric noncardia cancer and 20 esophageal squamous cell carcinoma incident cases and 25 controls in the Golestan Province, northern Iran, a high risk area for upper gastrointestinal cancers. Results: Mean serum hyaluronic acid and laminin concentrations in cancer cases were higher than in controls in crude analyses. Significant correlations were observed between hyaluronic acid levels and gastric noncardia cancer (Beta-coefficient = 0.390; P = 0.01) and esophageal squamous cell carcinoma (Beta-coefficient = 0.332; P = 0.05) and between laminin levels and gastric cardia cancer (Beta-coefficient = 0.454; P = 0.003) in multivariate models. For esophageal squamous cell carcinoma, gastric cardia cancer, and gastric noncardia cancer, area under ROC curve (AUC) of hyaluronic acid was 0.708, 0.694, and 0.770, and of laminin was 0.706, 0.828, and 0.671. Conclusions: Our study suggests that hyaluronic acid and laminin may be used to identify potentially high-risk groups of upper gastrointestinal cancers for further diagnostic work-ups, particularly in high incidence areas. Nevertheless, further studies with larger sample size and tumor staging information are warranted to clarify the clinical significance of hyaluronic acid and laminin in those cancers. © 2011 European Federation of Internal Medicine

Data structure implementation and correctness

Recently, implementation of data structures and correctness proofs of data structure implementations have become important problems in the construction of data abstraction languages, data base systems, and software engineering. The research reported here is primarily concerned with the definition and implementation of data structures, and how to prove an implementation correct;This thesis develops a general technique to implement the source data structure (d1) in terms of the target data structures (d2). That is, given data structures d1 and d2, an implementation of d1 by d2 is defined separately on the syntactical and semantical levels of data structure elements. This work makes a sharp distinction between the specification of a data structure and its implementation. Specification of data structures is considered to be abstract, that is, implementation independent of any specific programming language;This thesis deals primarily with developing criteria for providing provably correct implementation of data structures. The correctness of data structure implementation is developed on two levels: syntactical and semantical. Syntactically, correct implementations deal with algebraic equations (conditional and unconditional) that specify a data structure, while the semantically correct implementations define correctness on the basis of the semantic algebra in the data structure specifications. All the implementations are specified by tree transducers, reducing the problem of implementation to a problem of translation;The issue of tree transducers is addressed on the syntactic and semantic levels. Two key syntactical properties of tree transducers have been investigated. They are, the consistency and semiconsistency of tree transducers with respect to the algebraic equations defining the source and target data structures. These properties have been used for the syntactical correctness proof of the implementation of data structures. One of the key results of this thesis is the development of syntactically honest tree transducers, which is based on a lattice. It has been proved that syntactically honest tree transducers form a base for syntactically correct implementation of data structures