Miracle-dz/UniFAR-FTUs huggingface dataset:
Divisibility and Multiplicative Structure of Natural Numbers: Preservice Teachers' Understanding.

This study contributes to a growing body of research on teachers' content knowledge in mathematics. The domain under investigation was elementary number theory. Our main focus concerned the concept of divisibility and its relation to division, multiplication, prime and composite numbers, factorization, divisibility rules, and prime decomposition. We used a constructivist-oriented theoretical framework for analyzing and interpreting data acquired in clinical interviews with preservice teachers. Participants' responses to questions and tasks indicated pervasive dispositions toward procedural attachments, even when some degree of conceptual understanding was evident. The results of this study provide a preliminary overview of cognitive structures in elementary number theory. This study is a contribution to the growing body of research on teachers' content knowledge in mathematics. The specific content under investigation is elementary number theory. Elementary concepts of number theory, despite their importance to the field of mathematics, have received scant attention in mathematics education research. Previous studies have used concepts of elementary number theory as a mathematical context for investigating different issues; for example, Martin and Harel (1989) used notions of divisibility in research on preservice teachers' understanding of mathematical proof. Leron (1985) adapted a theorem on the infinity of prime numbers to illustrate a more constructive approach to indirect proofs. Lester and Mau (1993) used prime factors in research on problem solving in a course for prospective elementary school teachers. Movshovitz-Hadar and Hadass (1990) applied proofs for irrationality of square roots of prime numbers for investigating the pedagogical role of paradox and conflict resolution in the education of prospective mathematics teachers. In our research, number-theory concepts themselves are the primary focus of investigation, rather than a means to another end. The main emphasis of this study is concepts involving divisibility and the multiplicative structure of natural numbers. Previous investigations of multiplicative structures have focused mainly on contextual situations, that is, a story (word) problem that can be solved by applying either multiplication or division (e.g., Ball, 1990; Graeber, Tirosh, & Glover, 1989; Vergnaud, 1988). In accordance with this line of investigation, Schwartz (1988) considered arithmetical concepts and operations as
THE IMPLEMENTATION OF A "FUNCTION" APPROACH TO INTRODUCTORY ALGEBRA: A CASE STUDY OF TEACHER COGNITIONS, TEACHER ACTIONS, AND THE INTENDED CURRICULUM

This article reports a case study set in the context of a "function" curriculum approach to introductory algebra and involving a teacher and her ninth-grade class in a high school in Western Australia. The expectation that the teacher's actions would reflect the teaching philosophy implied in the curriculum was not supported by the study's findings. Instead, the teacher gave priority to curriculum content coverage, emphasized methods and procedures, and adopted teacher-focused pedagogical practices. Changes in the way students are taught introductory concepts in algebra are part of the reform movement in mathematics education that gathered strength during the 1980s. The numerous documents calling for reform, notably Mathematics Counts (Cockcroft, 1982), A Nation at Risk (National Commission on Excellence in Education, 1983), and the Standards documents of the National Council of Teachers of Mathematics (NCTM, 1989, 1991, 1995), make recommendations not only for curriculum content change, but also for changes in pedagogical practice. In the teaching of algebra, a focus for reform is a change from a "generalized arithmetic" approach to one in which functions provide the medium through which the concept of variable is developed. Because a "function" approach to the teaching of introductory concepts in algebra is comparatively new, there is need for studies concerning its impact in the classroom. The purpose of this article is to examine the extent to which the intended ("function") curriculum had an impact on the actions of one teacher. The article focuses on teacher cognitions because of their influence on how the curriculum is enacted.
Tissue-Specific Regulation of Iron Metabolism and Heme Synthesis: Distinct Control Mechanisms in Erythroid Cells

IRON IS INDISPENSABLE for life, serving as metal cofactor for many enzymes, either nonheme or hemoproteins. In the latter, iron is inserted like a gem in the center of the heme prosthetic group. Hemoproteins are involved in a broad spectrum of crucial biologic functions including oxygen binding (
Geographical patterns, and their origins, in the dominance of major ions in South African rivers

The proportions of ions in rivers of South Africa and Lesotho were investigated using Maucha diagrams, which allow a visual assessment of the ionic proportions of any water sample. Four broad categories of ionic proportions show clear geographical distribution patterns. Linked to the geological and climatological character of the country. Waters in categories I and 2 are 'rock dominated'; dilute waters in category 4 are 'precipitation (rainfall) dominated' and concentrated waters in category 4 are 'evaporation-precipitation (crystallization) dominated'. It is shown that dilute rainfall-dominated waters can become directLy evaporation-dominated in more arid areas.
Functional changes in the anatomy of the pharyngeal jaw apparatus ofAstatoreochromis alluaudi(Pisces, Cichlidae), and their effects on adjacent structures

Abstract Organisms are tightly packed with structures so architectonic interdependency of structures is an obvious aspect of integration. This aspect of functional morphology, however, has received remarkably little attention. The present paper presents an example of the spatial relations among several apparatuses in the head of the cichlid fish, Astatoreochromis alluaudi . It investigates the transformations of these apparatuses and their functions due to a change in the pharyngeal jaw apparatus resulting from a functional shift (insect eating to snail crushing or vice versa ). The volume of the pharyngeal jaw apparatus differs 55% between the insect eating- and the snail eating morph. The increase in volume of the pharyngeal jaw apparatus has an impressive number of spatial effects, both direct and indirect, on other structures. Reallocation of space within the pharyngeal jaw apparatus occurs. Total head volume increases 31% but a reallocation of space is still necessary as the increase of the opercular compartment where the pharyngeal jaw apparatus is situated compensates for only 59% of the volume increase of that. Not all spatial effects do impose constraints. Spatial constraints are avoided when one of the apparatuses can use a topographically different volume of space. The respiratory apparatus shows internal reallocations of space without loss of total volume. The same solution occurs for elements of the expansion apparatus and the buccal cavity. The eyes are not influenced. Finally spatial effects can have positive repercussions. The muscles of the oral jaw apparatus increase in size. This may be an example of an epiphenomenon.
Emission Spectra of Actinium

1 Small samples of actinium, produced by Lransmuting radium ha\'c been im'cstiO"aLcd ? pectroscopically by photographing Lhe spect'ra of light em.itted by thc samples when ex~ited III a hollow cathode or III ftrCS and sparks between copper or silver electrodcs. The wave lengths were measured, and intensities estim.ated, for some 500 lines eharaetcristic of aetinillm. in t he spectral range 2062.00 to 7886.82 A. A comparison of line characteristics in different sources permitted sorting into five categories; about 140 lines belong to Ae I, more than 300 were ascnbed to Ac II, 8 were dcfill itcly assigned to Ac nT, 5 may belong to Ae IV, and abouL 80 represent band heads characteristic of AeO, the actinium-monoxide molecule. Anal.yses of t he first three spectra of actinium have revealed their m.ost important features, Including atomic-energy levels, spectral terms, and electron configurations. The ground state of Ac I II is fou nd to be (78)280 ;>, t hat of Ac II is (7s 2) 18 0, and that of Ac I is (6d7s 2)2D1 ;> . Comparisons of the analogous spectra of the chemical homologs (scandium yttl"lllm, ]'wthanul11 , and actinium) sho\\' that ~etinium closel~' resembles yttrium, except that additIOnal terms of odd panty, first found 111 lanthanum spectra and attributed to the 4J electron, arc also found in actinium spectra, where Lhey pro\' ide evidence of the prcsenc(' of t he 5J cl~,etron. The bindi np; forc(' on the 4f elecl~'on i~l La II is much sLrong('[" than on 5J In . -'. c II.
Porous Clay Heterostructures from Al13 Intercalated Montmorillonites: Synthesis and Characterization

For the first time, we have used the intercalated montmorillonite with aluminium polyoxocations (Al13) as precursor for the synthesis of porous clay heterostructures (Al-PCHs) materials. They are obtained by simple addition of tetraethylorthosilicate (TEOS) and neutral amines with different lengths (C8 to C12) at a molar ratio of Al13-clay/amine/TEOS close to 1/20/150. The obtained Al-PCHs exhibited higher surface area of 880m2/g and pore volume of 0.85mL/g. The X-ray diffraction, and 29Si MAS NMR indicated the polymerization of silica species in the interlayer gallery, and two different octahedral aluminium conformations detected by 27Al MAS NMR, compared to the starting raw clay. Infrared spectroscopy of adsorbed pyridine suggests the presence of both Bronsted and Lewis acid sites up to 300•Ž. The thermal desorption of cyclohexylamine was used as further probe to monitor the acidity of the different materials.
Puberty, sexuality, and the self : boys and girls at adolescence

Puberty, Sexuality and the Self considers the effects of puberty and teenage sexuality on adolescents. By analyzing interviews with 55 teenagers, Karin Martin finds that girls' self-esteem drops significantly more than boys' does at adolescence. While this finding is supported by previous studies, Martin picks up where these earlier studies leave off by focusing on girls' development and considering different experiences of puberty and sex as an explanation for girls' greater drop in self-esteem. Puberty, Sexuality and the Self examines voice change, breast development, shaving, expectations of sex, the decision to have sex, experiences of sex and how boys and girls manage their emotions and selves throughout all of these new experiences. Comparing boys and girls at adolescence, Martin takes a qualitative look at puberty and sexuality, supporting her theory in the words of the adolescents themselves.
Li+ Ion Insertion in TiO2 (Anatase). 2. Voltammetry on Nanoporous Films

Electrochemical properties of Li+ ion insertion in nanoporous TiO2 (anatase) electrodes were studied by voltammetry. Linear and cyclic potential scans were recorded as a function of electrolyte concentration, film thickness, and temperature. The currents were directly proportional to the inner electrode area of the electrodes. The reduction of Ti4+ and oxidation of Ti3+ are sluggish and follows irreversible kinetics. The standard rate constant was (3.5 ± 0.5) × 10-10 cm/s. The transfer coefficient was close to 0.5, indicating that the potential drop appears mainly across the Helmholtz layer. The capacitive currents govern largely the shape of the i−v curves, except within a region near the peak potential where diffusion-limited insertion and extraction of Li+ ions in the anatase lattice are dominating. The diffusion coefficient at 25 °C in the nanoporous structure was approximately 2 × 10-17 cm2/s for insertion and 4 × 10-17 cm2/s for extraction. The activation energy was 0.4 eV for insertion and 0.5 eV f.
Stability analysis of feedback controlled resonant DC-DC converter using Poincare map function

The stability analysis of the buck member of a dual channel resonant DC-DC converter family is reported. The study is confined to the symmetrical continuous current mode. The output voltage of the converter is controlled by a feedback loop applying constant frequency PWM. The dynamic analysis applies to stability criterion the positions of the characteristic multipliers of the Jacobian matrix belonging to the Poincare map function defined around the fixed point located in the Poincare plane where the trajectory of the variable structure, piecewise linear, nonlinear system pierces through the plane. The study reveals that the process loses its stability as a result of varying the loop gain.
Intuitive Strategies and Preconceptions about Association in Contingency Tables

The aim of this research was to identify students' preconceptions concerning statistical association in contingency tables. An experimental study was carried out with 213 preuniversity students, and it was based on students' responses to a written questionnaire including 2 x 2, 2 x 3, and 3 x 3 contingency tables. In this article, the students' judgments of association and solution strategies are compared with the findings of previous psychological research on 2 x 2 contingency tables. We also present an original classification of students' strategies, from a mathematical point of view. Correspondence analysis is used to show the effect of item task variables on students' strategies. Finally, we include a qualitative analysis of the strategies of 51 students, which has served to characterize three misconceptions concerning statistical association.
In situ plasma contamination measurements by HeNe laser light scattering: A case study

Using a simple, inexpensive HeNe laser and a video camera to measure light scattering intensity and location, particulate contamination in an SiO2 sputtering process used in semiconductor manufacturing has been studied under actual process conditions in a class 10 cleanroom. Particulates were observed during all aspects of the sputtering process. It was seen that portions of the process which resulted in mechanical stress on the tool walls produced the greatest flux of particles inside the tool. However, the sputtering step was the major contributor to contamination in this chemically simple process, because of its long duration and the stress‐inducing nature of the plasma. The contamination level in this plasma is estimated to exceed the cleanroom ambient by three orders of magnitude. As in other process plasmas, the particles were suspended at the sheath/plasma boundary. It is argued that a relatively weak electrostatic field is required for gravitational counterbalance of these highly charged particles.
Gender-Related Differences in Self-Referenced Cognitions in Relation to Mathematics.

In this study, a number of learner variables that are related to mathematics achievement in actual learning situations were examined. The dynamic model of the learning process as developed by Boekaerts was taken as a starting point. Both trait-like self-referenced cognitions (viz., academic self-concept of mathematics ability, goal orientation, and attribution style) and situationspecific variables were included. In a group of 8th graders (ages 11-12; N = 186), marked differences between boys and girls on a mathematics test were found. These differences were parallelled by differences in both trait-like self-referenced cognitions and task-specific appraisals. It is concluded that boys experience learning situations where they are confronted with a mathematics test in a more positive way than girls do.
Effects of Coumarin Following Perinatal and Chronic Exposure in Sprague-Dawley Rats and CD-1 Mice

Coumarin, a naturally occurring substance most frequently used as a fragrance enhancer and stabilizer, was administered in the diet of Sprague–Dawley rats at dose levels of 0, 333, 1000, 2000, 3000, and 5000 ppm or in the diet of CD-1 mice at dose levels of 0, 300, 1000, or 3000 ppm. Rats receiving 333, 1000, and 2000 ppm coumarin were exposed to these dose levelsin uteroand during the lactational period, then chronically following weaning. Rats in the 3000- and 5000-ppm dose groups and all mice received only postweaning chronic exposure. All male rats were terminated after 104 weeks of postweaning exposure; female rats were terminated after 110 weeks. Male mice were terminated at Week 101 and female mice at Week 109. Among rats, survival was decreased at 333 ppm, but significantly increased among rats in the 3000- and 5000-ppm dose groups. Dramatic dose-related decreases in body weight gain were recorded for rats receiving 2000, 3000, and 5000 ppm, clearly indicating that the MTD (maximum tolerated dose, as indicated by a body weight decrement of greater than 10–15%) was exceeded. Food consumption also was decreased at the three highest dose levels, although body weight decrement was disproportionately large compared to changes in food consumption. Treatment-related decreases in hemoglobin were recorded from Week 6 onward. Minimal treatment-related changes in hematology and clinical chemistry were recorded. Increased liver weights were observed for male and female rats receiving 3000 or 5000 ppm and for females only at 1000 and 2000 ppm. Increased incidences of cholangiofibroma, cholangiocarcinoma, and parenchymal liver cell tumors were observed among male and female rats receiving 5000 ppm. One male rat receiving 3000 ppm developed a cholangiocarcinoma; no tumor increase was observed in males or females at 2000 ppm or below. Coumarin, at a dose clearly exceeding the MTD can, therefore, induce liver tumors in rats, although survival, relative to controls, was increased at the same dose levels. Among mice, a decrease in body weight gain was reported for males in the 1000- and 3000-ppm dose groups during the first 52 weeks of the study. No dose-related abnormalities in clinical signs, clinical pathology, hematology, or gross or microscopic pathology were noted.
Regulation of the D2-Like Dopamine Autoreceptor by the Dopamine Transporter.

xi CHAPTER ONE INTRODUCTION 1 The Dopaminergic System 1 The D2 Dopamine Receptor 5 Identification and Classification 5 Structure 6 Distribution and Cellular Localization 9 G protein coupling 10 Signaling 11 Desensitization and Internalization 13 The D2-Like Dopamine Autoreceptor 16 The Dopamine Transporter 19 Protein Kinase C 22
An Econometric Study of Advertising and Cigarette Demand in the United Kingdom

This article reports the results of an empirical investigation of the effect of total cigarette advertising on aggregate demand for cigarettes in the United Kingdom. The research is conducted within the framework of the Becker‐Murphy model of rational addictive behaviour, using time series spanning the period 1963–1992. No evidence is found in this research to back up the view that aggregate cigarette advertising has the effect of expanding total market demand for cigarettes.
Plasma Neopterin in Hepatitis C Virus Antibody -positive and -negative Donors with Elevated Alanine Aminotransferase Activity

Summary Plasma neopterin was assayed in units from HBs antigen-negative male donors with elevated levels of alanine aminotransferase (AL T, above 35 Karmen units) who were divided into two groups according to whether they were negative (N = 162) or positive (N =-= RO) for antibody to hepatitis C virus (HCV Ab). Male donors with no abnormalities reflected in screening tests were selected as controls (N98). The average values of plasma neopterin were 5.6 nmolll in the HCV Ab-negative group, 7.9 nmolll in the HCV Ab-positive group and 5.9 nmolll in the control group. Significant differences were only found between the HCVAb-positive group and each of the other two groups. From the results. the elevated ALT levels in the majority of HCVAb-negative donors with elevated AL T were considered to be clue to liver injuries caused by metabolic disturbances such as steatosis due to excess body weight and/or alcohol consumption.
TREATMENT OF GREATER-ZAB WATER BY DIRECT FILTRATION

In this research, a water treatment plant is designed to treat Greater-Zab River water by direct filtration. Direct filtration comprises of intakes, coagulation, flocculation, and filtration is not preceded by in-plant sedimentation of flocculated water. To ensure which season is suitable for using direct filtration process; turbidity values of GreaterZab water recorded throughout fourteen months, October 2004 to May 2005 and May 2006 to October 2006. Proposed treatment-plant units are designed and summary of design are outlined. Cost analysis of conventional treatment-plants and direct filtration discussed.
Lattice dynamics and vibrational spectra of polypyrrole

The interpretation of the infrared and Raman spectra of pristine polypyrrole as 1‐d lattice is presented as the result of lattice dynamical calculations. Geometries and vibrational force fields are derived from semiempirical quantum chemical calculations and/or from the optical spectra of oligomers. This paper lays the background information which are used in the second paper, which immediately follows, where the spectra of the conducting polymer are extensively discussed.
How we avoid collisions with stationary and moving objects.

When moving through cluttered environments we use different forms of the same source of information to avoid stationary and moving objects. A stationary obstacle can be avoided by looking at it, registering the differential parallactic displacements on the retina around it during pursuit fixation, and then acting on that information. Such information also specifies one's general heading. A moving obstacle can be avoided by looking at it, registering the displacements reflecting constancy or change in one's gaze-movement angle, and then acting on that information. Such information, however, does not generally specify one's heading. Passing in front of a moving object entails retrograde motion of objects in the deep background; collisions entail the lamellar pattern of optical flow; and passing behind entails more nearly uniform flow against one's direction of motion. Accuracy in the laboratory compares favorably with that of real-world necessities.
Lexical, Sublexical, and Implicit Memory Processes in Healthy Young and Healthy Older Adults and in Individuals With Dementia of the Alzheimer Type

Five groups of participants—healthy young, healthy young-old, healthy old-old, very mildly demented, and mildly demented individuals of the Alzheimer type (DAT)—participated in a 2-phase experiment that entailed a rhyme judgment task followed by a lexical decision task, in which half of the stimuli were earlier presented in the rhyme judgment task. The results of the rhyme task indicated that healthy young and older adults did not produce an influence of word frequency on rhyme decisions. However, the 2 groups of DAT individuals produced large word-frequency effects primarily for the nonrhyming pairs. The results of the lexical decision task indicated that (a) repetition facilitated lexical decisions to words, whereas there was evidence of inhibition for nonwords; and (b) there was an increasing influence of word frequency across the 5 groups of participants. The results are interpreted with respect to attentional control of appropriate (lexical and sublexical) processing pathways and the nature of processes that are disrupted and those that remain uninfluenced in healthy aging and DAT.