Logarithmic Form Research Articles

Scaling of adult human bone and skeletal muscle mass to height in the US population.

The scaling of structural components to body size is well studied in mammals, although comparable human observations in a large and diverse sample are lacking. The current study aimed to fill this gap by examining the scaling relationships between total body (TB) and regional bone and skeletal muscle (SM) mass with body size, as defined by stature, in a nationally representative sample of the US population. Subjects were 17,126 non-Hispanic (NH) white, NH black, and Mexican American men and women, aged ≥18 years, evaluated in the National Health and Nutrition Examination Survey who had TB and regional bone mineral (BMin) and lean soft tissue (LST) mass measured by dual-energy X-ray absorptiometry. BMin and appendicular LST served as surrogate bone and SM mass measures, respectively. The allometric model, BMin or LST = α(height)β , in a logarithmic form was used to generate scaling exponents. The findings were similar across all gender and race groups: body mass scaled to height with powers of ~2.0 (mean β ± SE, 1.94 ± 0.08-2.29 ± 0.09) while TB and appendicular BMin and appendicular LST scaled to height with consistently larger powers than those for body mass (eg, all P < .05 in NH white men and women); the largest BMin and LST scaling powers to height were observed in the lower extremities. Bone and SM mass, notably those of the lower extremities, increase as proportions of body mass with greater adult height. Metabolic and biomechanical implications emerge from these observations, the first of their kind in a representative adult US population sample.

The perturbation series method based on the logarithm equation for fatigue crack growth prediction

This paper gives the perturbation series method for the fatigue crack growth prediction accounting for the error in initial crack length. The proposed method utilizes the logarithm form of the crack growth equation and the solution of it is expressed in the form of asymptotic series by introducing a small parameter. The initial crack length is considered as a sum of the nominal value and the perturbation which mainly originates from manufacturing and measurement errors. Based on the Taylor series expansion and perturbation series method, a series of perturbation equations to predict the fatigue crack growth history are obtained. Then these equations can be solved by the successive approximation approach and the a-N curve which describes the relationship between crack length and number of load cycles can be obtained. Two examples with respect to fatigue crack growth experiments are given to verify the accuracy and validation of the presented method. The results show that the perturbation series method is closer to the experimental data compared with the original solution of crack growth equation and it can provide a more accurate prediction for the fatigue crack growth process.

Chance-Constrained Optimization in D2D-Based Vehicular Communication Network

In this paper, a novel scheme is proposed to optimize the effectiveness of the device-to-device (D2D) enabled vehicular communications (D2D-V), which are underlaid in cellular networks, where the uplink channel allocated to one cellular user (CU) is reused by the multiple D2D-V links. To develop a well-functioning D2D-V system, the sum rate of all D2D-V links is necessary to be maximized, and also the reliability of the co-channel CU to infrastructure has to be guaranteed with the CU interference constraint. Unlike the traditional statical D2D systems, the D2D-V system suffers with high mobility and channel uncertainty. Therefore, the CU interference constraint is formulated as a probabilistic function by the Bernstein approximation, the constraint attempts to address the mobile channel fluctuations. Besides, the tractable approximate constraint is reformulated as two separable structure, this reformulated constraint attempts to determine the near-optimal solutions more efficiently. Since the objective function with a logarithmic form is nonconvex, successive convex approximation is applied to transform the nonconvex problem into the convex problem. The dual decomposition is used to determine the near-optimal solutions. After the problem is reformulated, a distributed robust power control algorithm is proposed to perform the chance-constrained optimization. Numerical simulations are used to evaluate the performance of the proposed scheme. The simulation results show the impacts of system performance when applying the proposed scheme in vehicular environments with high mobility. The proposed optimization schemes are further verified by comparing with the existing methods.

DAMPAK UPAH MINIMUM TERHADAP PENYERAPAN TENAGA KERJA SEKTOR FORMAL DAN INFORMAL: ANALISIS SPASIAL

There is possibility of bias in previous study about impact of minimum wages on labor absorption in formal and informal sectors because it has not yet accommodated the spatial effects of inter-regional labor market dependencies. This study aims to examine impact increasing of minimum wage on labor absorption in formal and informal sector without spatial effects then compared with if there are spatial effects. Without spatial effect, the model used is panel model and with spatial effect, model used is Panel Spatial Auto-Regressive model. The dependent variable used is labor absorption in formal sector relative to informal sector, whereas the independent variable is the real minimum wage in the form of the natural logarithm. The result of both models showed that increasing of minimum wage significantly reduced the labor absorption of formal sector relative to informal sector. Coefficient value of the impact increasing of minimum wage produced by the spatial model is greater than the non-spatial model whereas from the model criteria results show better spatial model, so it can be concluded there is underestimate in the previous study which does not take into account the spatial dependencies of the labor market .

Faktor-faktor yang Mempengaruhi Permintaan Konsumen terhadap Cabai Rawit di Kota Denpasar Provinsi Bali

Factors Affecting Consumer Demand for Cayenne Pepper in Denpasar City,Bali ProvinceCayenne pepper is one of the national leading commodities that is needed by thecommunity. Denpasar City, which has a high population density and per capita foodexpenditure, is a potential market for cayenne pepper production centers in BaliProvince. Consumer demand for cayenne pepper is sometimes uncertain due to theinfluence of various factors. This study aims to analyze the factors that influenceconsumer demand for cayenne pepper and analyze its demand elasticity in DenpasarCity, Bali Province.This research was carried out in Badung Market, Kreneng Market,Ketapian Market, and Sanglah Marketwhich were determined intentionally. Samplingused accidental sampling technique. The number of samples was determined by quotasampling as many as 50 respondents. This study used the Cobb-Douglas requestfunction which is transformed into multiple linear forms of natural logarithms (ln).Theresults showed that the factors that influence consumer demand for cayenne pepper inDenpasar City, Bali Province were the number of family members and tastes. Priceelasticity at D = 0 (not interested in cayenne pepper) and D = 1 (interested in cayennepepper) shows that the demand for cayenne pepper is perfectly inelastic. Cross elasticityat D = 0 (not interested in cayenne pepper) and D = 1 (interested in cayenne pepper)showed that large red chilies, tomatoes, and shallots are items that were not related tocayenne pepper. Income elasticity at D = 0 (not interested in cayenne pepper) and D = 1(interested in cayenne pepper) indicates that the demand for cayenne pepper wasinelastic to income.

Nanoindentation characterization of aging gradient of mastic in asphalt mixtures

Abstract Understanding the aging behavior of asphalt mixtures is of great significance to the design, construction and maintenance of asphalt pavements. Numerous studies have been conducted on the aging phenomenon and its effects on mixture properties. However, conventional testing methods focus mainly on the global view or average value of the performance of aged mixtures, while the inner aging gradients are seldom addressed. The aging gradient, referring to the differences of aging effects in asphalt mixtures due to different accessibilities to aging conditions, represents the true aging behavior of asphalt mixtures. Hence, a micromechanical testing technique, nanoindentation, was used in this paper to investigate this issue. The effects of mixture gradation and polishing in sample preparation process on nanoindentation results were explored first. Then the vertical changes of modulus of asphalt mastic in asphalt mixture samples were characterized by nanoindentation to describe the aging gradient in different aged mixture samples. Dynamic modulus test was also performed for data supplement and comparison. Results show that gap-graded mixtures are suitable for nanoindentation test and a careful and standard polishing treatment will not affect the reliability of nanoindentation data. Nanoindentation can well characterize the age-hardening behavior of asphalt mastic and the aging gradient in long-term aged asphalt mixtures is approximately in a logarithmic curve form. Nanoindentation modulus results indicate that 8d of laboratory long-term aging in this paper can only affect the upper sections of dense asphalt mixtures. This paper suggests that nanoindentation can achieve a quantitative, mechanical and precise characterization of aging gradient in asphalt mixtures and is therefore promising in further research of asphalt materials.

A study of pilgrim dark energy model in Brans–Dicke theory

In this paper, we study the behavior of non-interacting and interacting pilgrim dark energy (DE) for non-flat FRW model in Brans–Dicke (BD) theory. We consider the future event horizon as well as logarithmic form of BD scalar field [Formula: see text], where [Formula: see text], [Formula: see text] and [Formula: see text] is the scale factor. We evaluate some well-known cosmological parameters such as equation of state as well as deceleration parameter and [Formula: see text] plane as well as statefinder parameters. We discuss graphical behavior of these parameters through pilgrim DE parameter [Formula: see text] for both non-interacting as well as interacting case with interacting parameter [Formula: see text]. It is found that the equation of state parameter gives consistent results with the current cosmic behavior while the deceleration parameter represents transition from decelerated to accelerated phase. The cosmological planes represent different DE regions. Finally, we discuss stability of the model through squared speed of sound in both cases.

Spatial-temporal distribution of debris flow impact pressure on rigid barrier

Grain composition plays a vital role in impact pressure of debris flow. Current approaches treat debris flow as uniform fluid and almost ignore its granular effects. A series of flume experiments have been carried out to explore the granular influence on the impact process of debris flow by using a contact surface pressure gauge sensor (Tactilus (R), produced by Sensor Products LLC). It is found that the maximum impact pressure for debris flow of low density fluctuates drastically with a long duration time while the fluctuation for flow of high density is short in time, respectively presenting logarithmic and linear form in longitudinal attenuation. This can be ascribed to the turbulence effect in the former and grain collisions and grain-fluid interaction in the latter. The horizontal distribution of the impact pressure can be considered as the equivalent distribution. For engineering purposes, the longitudinal distribution of the pressure can be generalized to a triangular distribution, from which a new impact method considering granular effects is proposed.

Prime powers in sums of terms of binary recurrence sequences

Let $$(u_{n})_{n \ge 0}$$ be a non-degenerate binary recurrence sequence with positive discriminant and p be a fixed prime number. In this paper, we are interested in finding a finiteness result for the solutions of the Diophantine equation $$u_{n_{1}} + u_{n_{2}} + \cdots + u_{n_{t}} = p^{z}$$ with $$n_1> n_2> \cdots > n_t\ge 0$$ . Moreover, we explicitly find all the powers of three which are sums of three balancing numbers using lower bounds for linear forms in logarithms. Further, we use a variant of the Baker–Davenport reduction method in Diophantine approximation due to Dujella and Pethő.

Lung fluid biomarkers for acute respiratory distress syndrome: a systematic review and meta-analysis

BackgroundWith the development of new techniques to easily obtain lower respiratory tract specimens, bronchoalveolar lavage fluid and other lung fluids are gaining importance in pulmonary disease diagnosis. We aimed to review and summarize lung fluid biomarkers associated with acute respiratory distress syndrome diagnosis and mortality.MethodsAfter searching PubMed, Embase, Web of Science, and the Cochrane Library for articles published prior to January 11, 2018, we performed a meta-analysis on biomarkers for acute respiratory distress syndrome diagnosis in at-risk patients and those related to disease mortality. From the included studies, we then extracted the mean and standard deviation of the biomarker concentrations measured in the lung fluid, acute respiratory distress syndrome etiologies, sample size, demographic variables, diagnostic criteria, mortality, and protocol for obtaining the lung fluid. The effect size was measured by the ratio of means, which was then synthesized by the inverse-variance method using its natural logarithm form and transformed to obtain a pooled ratio and 95% confidence interval.ResultsIn total, 1156 articles were identified, and 49 studies were included. Increases in total phospholipases A2 activity, total protein, albumin, plasminogen activator inhibitor-1, soluble receptor for advanced glycation end products, and platelet activating factor-acetyl choline were most strongly associated with acute respiratory distress syndrome diagnosis. As for biomarkers associated with acute respiratory distress syndrome mortality, interleukin-1β, interleukin-6, interleukin-8, Kerbs von Lungren-6, and plasminogen activator inhibitor-1 were significantly increased in the lung fluid of patients who died. Decreased levels of Club cell protein and matrix metalloproteinases-9 were associated with increased odds for acute respiratory distress syndrome diagnosis, whereas decreased levels of Club cell protein and interleukin-2 were associated with increased odds for acute respiratory distress syndrome mortality.ConclusionsThis meta-analysis provides a ranking system for lung fluid biomarkers, according to their association with diagnosis or mortality of acute respiratory distress syndrome. The performance of biomarkers among studies shown in this article may help to improve acute respiratory distress syndrome diagnosis and outcome prediction.

Shifted powers in Lucas–Lehmer sequences

We develop a general framework for finding all perfect powers in sequences derived via shifting non-degenerate quadratic Lucas–Lehmer binary recurrence sequences by a fixed integer. By combining this setup with bounds for linear forms in logarithms and results based upon the modularity of elliptic curves defined over totally real fields, we are able to answer a question of Bugeaud, Luca, Mignotte and the third author by explicitly finding all perfect powers of the shape $$F_k \pm 2 $$ where $$F_k$$ is the k-th term in the Fibonacci sequence.

Stability of logarithmic differential one-forms

This article deals with the irreducible components of the space of codimension one foliations in a projective space defined by logarithmic forms of a certain degree. We study the geometry of the natural parametrization of the logarithmic components and we give a new proof of the stability of logarithmic foliations, obtaining also that these irreducible components are reduced.

Mesures d’indépendance linéaire de logarithmes dans un groupe algébrique commutatif dans le cas rationnel

We establish new measures of linear independence of logarithms on a commutative algebraic group. Let G be a connected commutative algebraic group over Q−− and let tG be the tangent space at the origin. We consider a vector u∈tG⊗Q−C such that its image by the exponential map of the Lie group G(C) is an algebraic point p∈G(Q−−). Let V be a hyperplane in tG. We obtain lower bounds for the distance d(u,V) between u and V⊗Q−C in the rational case, where V=tH is the tangent space at the origin of an algebraic connected subgroup of G. These lower bounds are the best currently known in terms of the height h(p) of p. They generalize measures of linear forms in logarithms previously obtained by Gaudron. Our approach is based on new arguments which allow us to exclude the so-called periodic case in the demonstration, by revisiting previous work of Bertrand and Philippon. Our proofs also rely on tools from Bost’s slope theory of hermitian vector bundles. Moreover, we present ultrametric analogues of our results, and we deal with the case where V=tH is a linear subspace of any dimension.

Investigating the Relationship Between Workability and Water Absorption of Periwinkle Shell Ash Cement Concrete

In this paper, a comprehensive study on the relationship between workability in form of slump and water absorption, a permeability and durability property, of cement concrete blended with periwinkle shell ash is presented. Periwinkle shell ash was obtained from the granulation process of calcined periwinkle shells at a calcination temperature of 800°C. Concrete specimens were designed using the Scheffe’s simplex lattice theory. Standard experimental procedures using the slump height method was adopted in the determination of workability of concrete specimens. The water absorption of hardened concrete specimens was also determined from standard experimental procedures. Regression models of different forms; power, linear, logarithmic, exponential and polynomial forms were developed to correlate both properties using results from trial mixes. These models were subjected to validation tests using results from control mixes through F-Statistics. The models were also subjected to R2 analysis for further adequacy tests. Results obtained from this study revealed that although the 0.5 power model proved adequate, little correlation exist between both responses as illustrated from low R2 values obtained for all the models developed. It was therefore recommended that in models’ validations, adequacy tests be used in conjunction with verification test (R2 test) to prove the usefulness of such models’ and that the relationship between other PSA cement concrete properties be investigated.

Accurate and Efficient Explicit Approximations of the Colebrook Flow Friction Equation Based on the Wright ω-Function

The Colebrook equation is a popular model for estimating friction loss coefficients in water and gas pipes. The model is implicit in the unknown flow friction factor, f . To date, the captured flow friction factor, f , can be extracted from the logarithmic form analytically only in the term of the Lambert W -function. The purpose of this study is to find an accurate and computationally efficient solution based on the shifted Lambert W -function also known as the Wright ω-function. The Wright ω-function is more suitable because it overcomes the problem with the overflow error by switching the fast growing term, y = W ( e x ) , of the Lambert W -function to series expansions that further can be easily evaluated in computers without causing overflow run-time errors. Although the Colebrook equation transformed through the Lambert W -function is identical to the original expression in terms of accuracy, a further evaluation of the Lambert W -function can be only approximate. Very accurate explicit approximations of the Colebrook equation that contain only one or two logarithms are shown. The final result is an accurate explicit approximation of the Colebrook equation with a relative error of no more than 0.0096%. The presented approximations are in a form suitable for everyday engineering use, and are both accurate and computationally efficient.

The Nexus Between Tourism and Economic Growth: Case of Commonwealth of Independent States

In this study the relationship between tourism and economic growth examined with panel data analysis for the Commonwealth Independent States (Azerbaijan, Russian Federation, Ukraine, Armenia, Kazakhstan and Kyrgyzstan except Uzbekistan and Tajikistan – due to lack of data) for the period between 1995 and 2015. The data has been downloaded from World Bank Development Indicators with their natural logarithmic forms. At the empirical part of the study GDP per capita annual data (%) represents economic growth and international tourism receipts (of % total export) have been chosen as an indicator of tourism sector. The model has been tested with dynamic panel data analysis. Firstly preliminary tests have been applied to be sure about the the homogeneity of series (Delta test) and the cross-section depence (CDlm test) of each individuals. After that second generation unit root test (Hadri Kurozomi-2012) used to find out the level of stationary. Durbin-H co-integration test showed that there is co-integration between variables and finally Hurlin-Dumetriscu causality test (2012) does not support tourism-led growth hypothesis. So there is one-way causality from economic growth to tourism for selected countries.

Log-anharmonic oscillator and its large-N solution

Anharmonic oscillator is considered using an unusual, logarithmic form of the anharmonicity. The model is shown connected with the more conventional power-law anharmonicity [Formula: see text] in the limit [Formula: see text]. An efficient and user-friendly method of the solution of the model is found in the large-N expansion technique.

Advanced Iterative Procedures for Solving the Implicit Colebrook Equation for Fluid Flow Friction

The empirical Colebrook equation from 1939 is still accepted as an informal standard way to calculate the friction factor of turbulent flows (4000 &lt; Re &lt; 108) through pipes with roughness between negligible relative roughness (ε/D ⟶ 0) to very rough (up to ε/D = 0.05). The Colebrook equation includes the flow friction factor λ in an implicit logarithmic form, λ being a function of the Reynolds number Re and the relative roughness of inner pipe surface ε/D: λ = f(λ, Re, ε/D). To evaluate the error introduced by the many available explicit approximations to the Colebrook equation, λ ≈ f(Re, ε/D), it is necessary to determinate the value of the friction factor λ from the Colebrook equation as accurately as possible. The most accurate way to achieve that is by using some kind of the iterative method. The most used iterative approach is the simple fixed-point method, which requires up to 10 iterations to achieve a good level of accuracy. The simple fixed-point method does not require derivatives of the Colebrook function, while the most of the other presented methods in this paper do require. The methods based on the accelerated Householder’s approach (3rd order, 2nd order: Halley’s and Schröder’s method, and 1st order: Newton–Raphson) require few iterations less, while the three-point iterative methods require only 1 to 3 iterations to achieve the same level of accuracy. The paper also discusses strategies for finding the derivatives of the Colebrook function in symbolic form, for avoiding the use of the derivatives (secant method), and for choosing an optimal starting point for the iterative procedure. The Householder approach to the Colebrook’ equations expressed through the Lambert W-function is also analyzed. Finally, it is presented one approximation to the Colebrook equation with an error of no more than 0.0617%.

English

Using the lower bound of linear forms in logarithms of Matveev and the theory of continued fractions by means of a variation of a result of Dujella and Pethő, we find all $k$-Fibonacci and $k$-Lucas numbers which are Fermat numbers. Some more general results are given.

Ecuaciones de biomasa aérea y volumen para Pinus halepensis Mill., en Coahuila, México

Realizar estudios para medir la biomasa en ecosistemas terrestres es fundamental para evaluar los almacenes de carbono y cómo las especies forestales contribuyen a la mitigación del cambio climático. El objetivo de este estudio fue ajustar ecuaciones alométricas para estimar biomasa aérea y volumen de Pinus halepensis Mill. en la sierra de Zapalinamé, Coahuila. Se partió de la hipótesis de que las variables diámetro basal y altura predicen adecuadamente la biomasa aérea y el volumen de P. halepensis. Se utilizaron 40 árboles, con diámetro basal que varió de 25 cm a 75 cm. La biomasa de fuste y ramas (64%) fue en promedio el doble que la de hojas y ramillas (36%) y su proporción aumentó con respecto a la altura total del árbol, de acuerdo con la ecuación: y = 53.4 + 1.2x. Los mejores ajustes fueron en volumen (R2 = 0.82) y biomasa total (R2 = 0.77) con ecuaciones alométricas de forma lineal logarítmica, con diámetro y altura como variables independientes (lny = β0 + β1ln(Db2H). La biomasa aérea de P. halepensis fue 2.5 veces más pequeña que la de otras especies de coníferas, debido posiblemente a que los árboles de esta especie se ramifican casi desde la base del árbol. En promedio, 85% del árbol presentó ramas de entre 5 cm y 10 cm de diámetro.