bluuebunny/crossref_metadata_2025 huggingface dataset:
A Multiplication Algorithm for Two Integers
Authors: Pinchback C. L. , Tomer Damber S.
Published: November 2020

The term Vedic mathematics usually refers to a set of sixteen word formulas, or sutras, along with their corollaries, that have origin in the Vedas. The Vedas are ancient holy texts from India that can be characterized as the allencompassing repository of Hindu knowledge from eons past. The Urdhva-tiryagbhyam sutra, or algorithm, has similarities to the FOIL (first, outer, inner, last) method that is used in algebra to multiply two binomials. We first illustrate this sutra with examples. Then we focus on similarities between Urdhva-tiryagbhyam and the standard multiplication algorithm, justifications for it, and student projects that relate to this algorithm.
Activities for Students: A Matter of Survival
Authors: Young Victoria
Published: November 2020

The Data Analysis and Probability Standard of Principles and Standards for School Mathematics (NCTM 2000) urges students in all grades to devise ways to gather and analyze data. The vast quantities of data that will confront these future citizens, businesspeople, consumers, and medical patients will be overwhelming unless they have the tools that they need to interpret these data. Probability simulations offer ways to quickly gather abundant data, and current technology can readily support the accumulation of randomly generated results. This activity facilitates the implementation of these mathematical goals in an appealing way.
Sound Off!: Computer Algebra Systems in Secondary Mathematics Classes: The Time to Act Is Now!
Authors: Heid M. Kathleen
Published: November 2020

Technology is giving us an opportunity to open new doors to mathematical understanding for our students, and we are failing to take advantage of that opportunity. Computer algebra systems (CASs)—and in particular, CAScapable calculators—provide ready classroom access to automated graphical, numerical, and symbolicmanipulation capabilities; and they should be as much a part of our students' mathematical repertoires as paper-and-pencil strategies or mental arithmetic. However, very few students in the United States have ever been afforded the opportunity to learn mathematics by using these tools.
Finding All Coefficients of a Polynomial with One Calculation
Authors: Satianov Pavel
Published: November 2020

The ideas discussed in this article were generated and developed at a seminar for high school teachers that was held at the Center for the Teaching of Science and Technology at the Ben-Gurion University of the Negev (Israel).
Activities for Students: Using Graphs to Introduce Functions
Authors: Dyke Frances Van
Published: November 2020

HE PAST DECADE HAS SEEN A SHIFT TOWARD FUNCTIONS as a central theme in beginning algebra. The advent of graphing calculators has meant that the graphical representation of functions is accessible and can be used in a meaningful way. Yet evidence indicates that students ignore graphs and resort to complicated algebraic expressions rather than read information from a graph. In “Understanding Connections between Equations and Graphs,” Eric Knuth (2000) reported on a study that he conducted with 178 students from a suburban high school. He concluded that students may be missing the basic “Cartesian connection” and that they do not recognize that a graph and an equation are two representations for the same set of points.
Media Clips: March 2003
Authors: Harlos Carol Ann
Published: November 2020

We welcome and encourage submissions to this department, which will comprise resources that teachers can use immediately or file away for future use. The assignments generated by these entries may range from starters for an entire class to full-blown projects for optional individual pursuit. Each lesson, though, should help convince our students that mathematics is useful, current, and newsworthy. Please send submissions to “Media Clips,” Mathematics Teacher, 1906 Association Drive, Reston, VA 20191-1502.
A Problem-Posing Approach to Specializing, Generalizing, and Extending Problems with Interactive Geometry Software
Authors: Contreras José N.
Published: November 2020

Mathematicians and mathematics educators (e.g., Brown and Walter [1990]; Freudenthal [1973]; Halmos [1980]; Kilpatrick [1987]; Moses, Bjork, and Goldenberg [1990]; Pólya [1954]; and Silver [1994]) consider problem posing to be an important mathematical activity and therefore believe that students should have experiences posing problems. For instance, Kilpatrick argues that the experience of “creating one's own mathematics problems ought to be part of every student's education” (1987, p. 123). In the same vein, reform documents of the National Council of Teachers of Mathematics strongly support the inclusion of problem posing both as a curricular activity and as a means of instruction (NCTM 1989, 1991, 2000). For example, Principles and Standards for School Mathematics states that teachers should “regularly ask students to formulate interesting problems based on a wide variety of situations, both within and outside mathematics” (NCTM 2000, p. 258).
Projects: Appalachian Mathematics and Science Partnership
Authors: Eakin Paul
Published: November 2020

The Appalachian Mathematics and Science Partnership (AMSP) is a National Science Foundation Math Science Partnership (MSP) project (NSF 0227028) that consists of 52 school districts in eastern Kentucky, northeastern Tennessee, and western Virginia, together with nine institutions of higher education. It was proposed in spring 2002 and received its initial funding effective October 1, 2002. The overall focus and primary purpose of AMSP is to help improve all students' performance in mathematics and science throughout the region.
Sound Off!: A Way of Teaching
Authors: Stueben Michael A.
Published: November 2020

The 1999–2000 year was my best teaching year ever for student academic achievement. I attribute this success mainly to a teaching philosophy that I have developed during the last five years.
The Essential Fairness of a Mortgage Loan: Developing Financial Literacy
Authors: White Wes
Published: November 2020

Many people know very little about finance. Few people, for example, can answer a finance question as natural and useful as, If I set aside $100 a month for 20 years at 5 percent annual interest, how much
Sherlock Holmes, Geometry Proofs, and Backward Reasoning
Authors: Gole Andy M.
Published: November 2020

A method for solving two-column geometric Proofs - backwards thinking. This approach generalizes to solving a number of important problems.
Unveiling Student Understanding: The Role of Questioning in Instruction
Authors: Manouchehri Azita , Lapp Douglas A.
Published: November 2020

The nature of question posing and categorization of types of questions in relation to the desired purpose. Suggestions for obtaining richer information of what students understand are discussed.
Calendar Problems: January 2004
Authors: Benson Steve
Published: November 2020

Problems 2–11 and 26–31 appeared in The Contest Problem Book IV: Annual High School Examinations, 1973–1982, compiled and with solutions by Ralph A. Artino, Anthony M. Gaglione, and Niel Shell (Washington, D.C.: Mathematical Association of America, 1983). Problems 12–17 come from Five Hundred Mathematical Challenges, by Edward J. Barbeau, Murray S. Klamkin, and William O. J. Moser (Washington, D.C.: Mathematical Association of America, 1995). Problems 18–23 were taken (or adapted) from problems appearing in the New York City Interscholastic Mathematics League competitions during fall 1977 and spring 1977. Problems 24 and 25 come from Problem Solving through Recreational Mathematics, by Bonnie Averbach and Orin Chein (Mineola, N.Y.: Dover Publications, 2000).
People Count: Analyzing a Country's Future
Authors: Kranendonk Henry A.
Published: November 2020

Mark Twain stated, “The art of prophecy is very difficult—especially with respect to the future.” Uncertainty presents an experience that is both challenging and humbling for students and teachers of applied mathematics. The headline of an article by Jean H. Lee published in the Milwaukee Journal Sentinel on February 28, 2001, read “World Population May Rise by 3 Billion in 50 Years.” On March 1, 2001, another headline in the Milwaukee Journal Sentinel read “As the Population Shrinks: Burden of an Aging World.” When students analyze population data, they understand how such divergent headlines as these examples can both be accurate. The topics discussed in this article are designed to develop new insights regarding population data.
Delving Deeper: Fibonacci and Related Sequences
Authors: Askey Richard A.
Published: November 2020

IN A COURSE ON PROOFS THAT IS PRIMARILY FOR PREservice teachers, a number of problems deal with identities for Fibonacci numbers. We consider some of these identities in this article, and we discuss general strategies used to help discover, prove, and generalize these identities.
Technology Tips: September 2004
Authors: Stohl Hollylynne , Harper Suzanne R.
Published: November 2020

In this month's “Technology Tips,” we introduce readers to some of the graphing capabilities of The Geometer's Sketchpad (Version 4.05, KCP Technologies 2001). You can download a free upgrade from Version 4.0, download an Instructor Evaluation Edition (60-day trial), or purchase a licensed copy from www.keypress.com/sketchpad. If you would like an overview of the software, you can download the Workshop Guide from www.keypress.com/sketchpad/ workshop_guide.html.
Delving Deeper: A Journey with Circumscribable Quadrilaterals
Authors: Worrall Charles
Published: November 2020

If we want to inspire a talented young writer to be a poet, we do not start with a grammar book. Instead, inspiration and love of literature come from reading complex works of art like Hamlet or Catcher in the Rye. Promoting a similar idea, Einstein wrote, “the mysterious… is the source of true art and science” (Ulam 1976, p. 289). To be more specific, one way to develop urgency and curiosity in mathematics students is to encourage them to wrestle with complex mathematical objects, ones whose deep and mysterious relationships are waiting to be found.
Report From the Netherlands: The Dutch Revolution in Secondary School Mathematics
Authors: Case Robert W.
Published: November 2020

The Dutch are in the midst of a powerful nationwide revolution in secondary school mathematics. This change in the approach to curriculum is known in the Netherlands as Realistic Mathematics Education, and a fundamental renewal of teaching methods and learning styles has also occurred. These developments are analogous to changes advocated by the National Council of Teachers of Mathematics (NCTM 2000), and the Dutch model is being constructed on much the same social ground as that found in the United States. Although Dutch and U.S. societies differ, these differences are outweighed by core similarities. Both countries are Western, high–technology, liberal, democratic societies that are moving toward a knowledge–based economy. In addition, large immigrant populations in the urban centers of both nations are a central concern for educational equity.
Delving Deeper: Fibonacci Identities, Matrices, and Graphs
Authors: Huang Danrun
Published: November 2020

In “Fibonacci and Related Sequences” published in the “Delving Deeper” department of the Mathematics Teacher February 2004, Richard Askey presents “general strategies used to help discover, prove, and generalize” identities for Fibonacci numbers. He also suggests some problems for further delving, including proving one key identity by using matrices. That proof is the focus of this article.
Activities for Students: Teaching Probability and Statistics Using Game Shows
Authors: Carlton Matthew A. , Mortlock Mary V.
Published: November 2020

The mathematical branch of probability has its origins in games and gambling. And so it is not surprising that our most common examples for teaching probability in the classroom—coins, dice, and cards—come from this domain. But how else can we teach probability, once these basic examples have been exhausted? Television game shows provide an answer. What we present here is just one of the game shows we have used to introduce students to several aspects of statistics and probability and to spark their interest in these topics.
Linking Theory and Practice in Teaching Geometry
Authors: Groth Randall E.
Published: November 2020

Regarding the relationship between theory and practice in teaching mathematics, Anna Sfard (2003) wrote,
Connecting Procedural and Conceptual Knowledge Of Functions
Authors: Davis Jon D.
Published: November 2020

From 1989 through 1991 the National Science Foundation (NSF) solicited proposals for curricula that would embody the goals set forth in the Curriculum and Evaluation Standards for School Mathematics (NCTM 1989) and other documents such as Everybody Counts (National Research Council 1989). Eventually thirteen curricula at the elementary, middle, and secondary levels were developed with funds from NSF (Senk & Thompson 2003). More than ten years later evidence is beginning to accrue that students enrolled in these Standardsbased curricula learn how to solve problems set within real-world contexts and do well on standardized tests that measure more traditional material (Senk & Thompson 2003).
Activities for Students: Biology as a Source for Algebra Equations: Insects
Authors: Horak Virginia M.
Published: November 2020

The integration of mathematics and other content areas has long been advocated by mathematics educators and sought after by teachers of mathematics, from kindergarten through high school and beyond. Science is one area that provides context and content for many valuable and useful connections with mathematics. When attempts are made to integrate mathematics and science, it seems that all too often mathematics is thought of as a “computational tool” for the sciences. For example, students need to have these computational tools for data analysis, so they can work with the data they collect in their science experiments. This use is not bad. However, it does not help students see the full power, usefulness, and beauty of mathematics. Beyond computation, mathematics can be used to determine and model science relationships, explain complex applications and, of course, solve problems.
Good Will Hunting Meets Graphing Calculators and CAS
Authors: O'Donnell William J. , Gibbs Richard A.
Published: November 2020

A solution, using CAS, to a graph theory problem that was presented in the movie Good Will Hunting. The author employs matrices, matrix multiplication and basic graph theory to solve the four part problem.
Multiple Solutions: More Paths to an End or More Opportunities to Learn Mathematics
Authors: Zbiek Rose Mary , Shimizu Jeanne
Published: November 2020

Similarities and differences among multiple solutions to two different problems (How much skin covers the human body? and How many melon balls in a melon?) and how thinking about the differences among problems and their solutions can be used to extend students' understanding of mathematical concepts and skills. The article discusses the teachers' questioning skills as they focused on the conceptual and procedural aspects of the alternative solutions. The authors noted that when the solutions differ conceptually, the conceptual diversity of solutions helps students refine their understanding of definitions and nuances of underlying concepts.
Delving Deeper: Simple Recurrence Relations, Proper Guessing, and Closed-Form Solutions
Authors: Nandor M. J.
Published: November 2020

In reading the February 2004 issue of the Mathematics Teacher, I found the wonderful “Delving Deeper” article “Fibonacci and Related Sequences,” by Richard Askey. At the end, in the editors' note, the question was posed whether Fibonacci numbers can be found in a closed form. As it happened, I was teaching that exact topic in my discrete mathematics class at the time. Ever since taking discrete mathematics in college, recurrence relations have fascinated me, and the derivation of a functional form of the Fibonacci sequence is just one great example of how recurrence relations can be used, even at the high school level.
Understanding Conic Sections Using Alternate Graph Paper
Authors: Brown Elizabeth M. , Jones Elizabeth
Published: November 2020

A description of two alternative coordinate systems and their use in graphing conic sections. This alternative graph paper helps students explore the idea of eccentricity using the definitions of the conic sections. Includes multiple examples of the uses of these alternative graphing sections, along with focus - directrix definitions of conic sections to be used with the new coordinate systems.
Connecting Research to Teaching: Good Things Always Come in Threes: Three Cards, Three Prisoners, Three Doors
Authors: Rubel Laurie H.
Published: November 2020

Readers are likely to be familiar with the infamous Monty Hall problem, played on the Let's Make a Deal game show and later addressed in the “Ask Marilyn” column in a 1990 issue of Parade.
Three by Three Systems: More than Just a Point
Authors: Ordinans Joseph
Published: November 2020

In working with 2 × 2 systems of equations, there are three possibilities: the two lines intersect at a point, called a consistent, independent system; the lines are parallel, called an inconsistent system; or the lines coincide, called a consistent, dependent system.
Proofs That Students Can Do
Authors: Stanton Robert O.
Published: November 2020

Contrary to the impression given by many secondary school programs, proof is an essential part of mathematics.
ON THE REALISTIC STRESS SPACE OF SOLIDS
Authors: LIU SHU-I  ,   北京钢铁工业学院
Published: November 2020

Solids can not be infinitely stressed under all stress states, thus only certain portion of the stress space has significance for solids. The shape, size and structure of this portion of stress space is closely connected with the mechanical properties of solids. By "realistic stress space of solids", is meant this portion of the stress space. Although some aspects of this problem had been investigated by some authors, there exists even no definite concept regarding the shape, structure and properties of the realistic stress space of solids up to this date.
ON SOME VARIATIONAL PRINCIPLES IN THE THEORY OF ELASTICITY AND THE THEORY OF PLASTICITY
Authors: HU HAI-CHANG  ,   中国科学院数学研究所
Published: November 2020

In this paper, some general variational principles in the theory of elasticity and the theory of plasticity are established. Consider an elastic body in equilibrium with small displacement. By regarding u, v, w, ex, ey, ez, yyz, yxz, yxy, σx,σy, σz,τyz,τxz,τxy as fifteen independent functions, and letting their variations be free from any restriction, we establish two variational principles, called the principle of generalized complementary energy and the principle of generalized potential energy. Each principle is equivalent to the four sets o?fundamental equations of the theory of elasticity, namely, the equations of equilibrium, the stress strain relations, the strain displacement relations and the appropriate boundary conditions. Special cases of these principles are examined. These principles are next expressed in other forms, where u, v, w, σx,σy, σz,τyz,τxz,τxy are regarded as nine independent functions with their variations free from any restrictions. Next we consider the bending of a thin elastic plate with supported edges under large deflection. By regarding Mx, My, Mxy, Nx, Ny, Nxy, u, v, w as nine independent functions with the restriction that w should vanish along the contour of the plate, we establish a variational principle, called the principle of generalized potential energy, which is equivalent to the three sets of fundamental equations in the theory of bending of thin plate, namely, the equations of equilibrium, the displacement stress relations (strain stress relations) and the appropriate boundary conditions. This principle is next expressed in another form which is more convenient for application. As an illustration, von Kármán's equations for the large deflection of thin plate are derived from this principle. In von Kármán's equations, one unknown is the deflection and the other unknown is the membrane stress function. Therefore it is impossible to derive von Karman's equations either from the principle of minimum potential energy or from the principle of complementary energy. Finally we consider the equilibrium of a plastic body with small displacement. In the case of the deformation type of stress strain relations, we establish two variational principles, each of which is equivalent to the equations of equilibrium, a certain type of stress strain relations and the appropriate boundary conditions. In these variational principles, u, v, w and their variations are free from any restriction, and σx,σy, σz,τyz,τxz,τxy and their variations satisfy a certain yield condition. In the case of the flow type of stress strain relations, we get two similar variational principles, in which u, v, w and their variations are free from any restriction, σx,σy, σz, τyz,τxz,τxy and their variations satisfy a certain yield condition and σx,σy, σz, τyz,τxz,τxy have no variations.
ON MULTIPLE PRODUCTION OF MESONS BY HIGH ENERGY NUCLEON COLLISIONS
Authors: HU NING  ,   中国科学院物理研究所,北京大学物理系
Published: November 2020

A possible quantum mechanical picture of multiple production of mesons is discussed in the present paper. The theoretical result is in agreement with the experimental evidences. The picture presented in the present paper is different from that given by Fermi. More experimental deta are needed for the comparison of these two theories.
A NEW METHOD OF DETERMINATING THE STATIC CHARACTERISTICS OF A POWER TUBE
Authors: LIN YI-KUN  , FENG PING-CHUAN  ,   (1)华南工学院电机系; (2)中山大学物理系
Published: November 2020

This paper presents a method by which a complete set of static characteristics of a power tube, including that of positive grid region, can be seen all at once on the screen of a cathode ray oscilloscope. Use is made of pulse-technique and intensity modulation of a cathode ray tube. Circuits are given and explained for observing plate characteristics on the plate current-plate voltage plane as well as constant current contours on the plate voltage-grid voltage plane, the former being shown in fig. 11 and the latter in fig 21. It is believed that the method here described will be of some help to tube manufacturers.
THE ANOMALOUS MAGNETIC MOMENT OF NUCLEONS
Authors: Yü MIN  ,   中国科学院物理研究所
Published: November 2020

The nucleon magnetic moments and the neutron-electron interaction potential have been calculated using the theory of pseudo-scalar mesons with pseudo-vector coupling. The divergence in the neutron-electron interaction is removed after the vacuum polarization effect due to virtual mesons has been taken into account. The final result is the same as in the case of pseudo-scalar coupling.
A THERMODYNAMICAL STUDY OF INTERNAL FRICTION
Authors: CHENG KAI-CHIA  ,   南京大学
Published: November 2020

Detailed theoretical investigations on the nature of internal friction of linear type have been made by Zener and others. It appears that their results are not systemmatic enough owing to the lack of generality. In particular, very little has been attempted to the illucidation of the nature of mutual interactions due to causes which give rise to internal friction.In this paper a theory is proposed based on the general theory of thermodynamics ol irreversilc processes together with the Boltzmann superposition principle. A comparison is made of the results of both theories. It is found that definite variance exists in the instances in which the mutual interactions become predominant. It would therefore appeal to further experimental demonstrations. In view of the recent rapid progresses in the experimental studies of anomalous and amplitude dependent internal frictions, it would be of interest to carry out a programm of study of the internal friction of non-linear type by the procedures similar to that proposed in the text.
ON THE INTERNAL FRICTION PEAK ASSOCIATED WITH THE PRESENCE OF CARBON IN NICKEL
Authors: KE TING-SUI  , TSIEN CHIH-TSIANG  , KAREL MISEK  ,   (1)捷克斯洛伐克科学院技术物理研究所; (2)中国科学院金属研究所
Published: November 2020

It is well-known that the stress-induced rotation of the magnetic domains in nickel gives rise to an internal friction peak (when internal friction is plotted as a function of temperature of measurement). An internal friction peak associated with the presence of carbon in nickel was recently observed in our laboratory. In this paper are described further experiments which demonstrate conclusively that this new internal friction peak is not connected with ferromagnetism of nickel but depends upon the amount of carbon in solid solution in nickel. More accurate determinations of the activation energy associated with this internal friction peak show that this activation energy is indeed very close to the activation energy for the diffusion of carbon in nickel. These experiments thus show that the new internal friction peak is associated with the stress-induced micro-diffusion of carbon in nickel.A brief discussion on the mechanism of this internal friction peak in terms of the existence of holes in the crystal lattice of nickel is given.
HIGH ORDER EQUATIONS IN QUANTUM THEORY
Authors: CHANG TSUNG-SUI  ,   中国科学院数学研究所
Published: November 2020

The purpose of this short paper is to compare the two existing theories of quantization of equations of motion containing high derivatives. As well known, when the order of the derivatives of field quantities q are finite, it is possible in certain cases to express q as a linear combination of quantities Q, each of which satisfies an equation of the second order. Quantization proceeds as if the various Q are independent. On the other hand, one may, following Ostro-gradski, put the equations of motion for the variables q in canonical form and then perform a subsequent quantization. (Such a theory was also discussed by the author in an earlier paper.) It is obviously worthwhile to see if the two theories are identical.In the following it is proved that the above two theories are in fact identical, both with respect to the commutation rules between q, Q and their derivatives and with respect to the total Hamiltonian.The importance of the above result lies in:(i) just as in the first theory, the Hamiltonian in the second theory is also not positive definite. In other words, possibilities of obtaining in the second theory positive definite Hamiltonians for field equatiens of certain types are found not to exist.(ii) just as in the second theory, q and its first few derivatives commute. This implies that in extending the first theory formally to cases containing derivatives of infinite order, q and all its derivatives of finite order commute. Since this is an undesirable feature, formal extension of the two theories to cases containing derivatives of infinite order seems difficult.
THE RELATION BETWEEN SPECTRAL LINE INTENSITY AND CONCENTRATION OF THE CONSTITUENT IN THE PRESENCE OF SELF-ABSORPTION
Authors: HO I-DJEN  , HSU SHENG-MEI  ,   中国科学院金属研究所
Published: November 2020

The functional relationship between intensity(I) of an emitted line and concentration ( C ) of emitting atoms serves as the physical basis for quantitative spe-ctrochemical analysis. The presence of self-absorption in spectral lines of most laboratory light sources, however, makes the dependence of I on C complicated.A study of variation of slope ( b )of the calibration curve (Si 2516-Fe 2518) with concentration of silicon in cast iron samples by the "transfer method" of spectral analysis was carried out under the condition that within the range of Si content studied, Si 2519 was free from self-absorption and Si 2516, the most intense component of the multiplet was showing self-absorption. A straight line has been obtained by plotting 6 versus log I2519 which was used as a measure of log C. From the slope ( k ) of this straight line, following relationships were derived: b=klogC+β+1,(1) and logI=k/2(logC)2+(β+1)logC+α, (2) where β and α are experimental constants. In the case of Si 2616, the value of k has been found to be about-(1/2) The change of spectral intensity with concentrationin the presence of self-absorption expressed by equation ( 2 ) was found to be in agreement with laboratory observations in general.
Circular dichroism of honeycomb-shaped elliptical hole absorber
Authors: Yu Peng , Wang Bao-Qing , Wu Xiao-Hu , Wang Wen-Hao , Xu Hong-Xing , Wang Zhi-Ming ,   Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, China,   Shandong Institute of Advanced Technology, Jinan 250100, China,   School of Physics and Technology, Wuhan University, Wuhan 430072, China
Published: November 2020

The circular dichroism of chiral structure has been widely used in analytical chemistry, industrial pharmacy, biological monitoring, etc. However, the light-matter interaction between natural chiral structures is extremely weak. Plasmonic nanostructures can significantly enhance light-matter interaction. During the fabrication of the visible-to-near-infrared chiral plasmonic metamaterial absorbers, there exists usually a trade-off between the absorption and the sample area, that is, the circular dichroism signal of the large-area structure is small. Besides, the preparation of chiral absorbers working in the visible and near-infrared region usually requires expensive etching or lithography equipment, such as reactive ion etching or electron beam lithography. Therefore, preparing cost-effective chiral absorbers with large circular dichroism is attractive for practical applications. In order to improve the circular dichroism of large-scale chiral absorbers, a honeycomb-shaped elliptical hole absorber is proposed in this paper, and its absorption, circular dichroism, and optical g-factor are studied. By reasonable design, the numerical calculation results show that the circular dichroism can reach about 0.8 under the excitation of chiral polarized light, and the corresponding optical g-factor can reach about 1.7 at 920 nm. Compared with the reported absorber, our chiral absorber has a maximum g-factor value. The giant circular dichroism originates from the symmetry breaking of the structure by tilting ellipse structures, and the tilt angle has a significant influence on circular dichroism. To further explain the absorption difference, the electric profile, surface current distribution, and absorption loss of the chiral absorption at resonant wavelength are analyzed. Finally, we point out that the structure can be prepared by existing technologies, such as nanosphere photolithography: first, a layer of polystyrene (PS) balls is formed by self-organization, which can control the period of the structure; then the size of the PS balls is reduced to a suitable size and spacing by the reactive ion etching; finally, a metallic layer is deposited by oblique angle evaporation. This work provides useful guidance for fabricating the large-scale chiral plasmonic absorbers.
Research progress of spin light emitting diode
Authors: Liang Shi-Heng , Lu Yuan , Han Xiu-Feng ,   Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China,   Faculty of Physics and Electronic Science, Hubei University, Wuhan 430062, China,   Institute Jean Lamour, Centre National de la Recherche Scientifique, Nancy 54011, France,   Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
Published: November 2020

After more than 20 years of development, semiconductor spintronics has become an important and interdisciplinary research filed of spin-based physics, materials and phenomenon. Spin light emitting diode (spin LED) is one of the fascinating topics in semiconductor spintronic, and it is also one of devices in which the radiative recombination of spin-polarized carriers results in luminescence exhibiting a net circular polarization. The research of spin LED involves the studies of materials, structures, and spin based physics in spin injector and active region. The spin injection, spin transport, and spin detection are key factors for understanding the spin based physics in spin LED. Here in this paper, we comprehensively review the current research status and the latest results. Finally, we also discuss the future research trend.
Terahertz spectroscopy study of doping and magnetic field induced effects on spin reorientation in Ho1–xYxFeO3 single crystals
Authors: Ren Zhuang , Cheng Long , Sergei Guretskii , Nadzeya Liubochko , Li Jiang-Tao , Shang Jia-Min , Sergei Barilo , Wu An-Hua , Alexandra Kalashnikova , Ma Zong-Wei , Zhou Chun , Sheng Zhi-Gao ,   High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China,   University of Science and Technology of China, Hefei 230026, China,   Scientific-Practical Materials Research Centre of NAS of Belarus, Minsk 220072, Belarus,   Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China,   Ioffe Technologies Institute, St. Petersburg 194021, Russia
Published: November 2020

In this paper, the effects of magnetic field and nonmagnetic Y3+ doping on spin state and spin reorientation in HoFeO3 single crystal are systematically studied by the self-developed terahertz time-domain spectroscopy (THz-TDS) under magnetic field. By doping nonmagnetic Y3+, we find that the spin reorientation temperature range decreases. Meanwhile, we also find the type of spin reorientation of HoFeO3 does not change with Y3+ doping, indicating that the Y3+ doping can exchange the interaction energy of Ho3+-Fe3+ without introducing any new magnetic structure. Moreover, the resonance frequency of quasi-ferromagnetic mode (q-FM) decreases with temperature increasing in the low temperature range, while the resonance frequency of quasi-antiferromagnetic mode (q-AFM) increases with temperature increasing in the high temperature range in Ho1–xYxFeO3 single crystals. With the external magnetic field ( H DC) applied along the (110) axis, on the one hand the magnetic field can not only tune the resonant frequency of q-FM but also induce the spin reorientation in Ho1–xYxFeO3 single crystals, and on the other hand this magnetic field induced spin reorientation phenomenon can happen more easily if the temperature approaches to the intrinsic spin reorientation temperature range of the single crystals. Besides, the critical magnetic field induced spin reorientation increases with the doping of Y3+ increasing. Our research shows that THz spectroscopy data can be used to detect the doping concentration of Y3+ ions in HoFeO3; in addition, Y3+ doping can make the spin state in HoFeO3 crystal more stable and not easily affected by external magnetic fields. We anticipate that the role of doping and magnetic field in spin reorientation transition will trigger great interest in understanding the mechanism of the spin exchange interaction and the mechanism of external field tuning effect in the vast family of rare earth orthoferrites.
An Overview of the History of Projective Representations of Groups
Authors:   Marin Drinov  Academic Publishing House, Aktay Sirin
Published: November 2020

In this work we investigate the possible classes of seven-dimensional almost paracontact metric structures induced by the three-forms of $G_2^*$ structures. We write the projections that determine to which class the almost paracontact structure belongs, by using the properties of the $G_2^*$ structures. Then we study the properties that the characteristic vector field of the almost paracontact metric structure should have such that the structure belongs to a specific subclass of almost paracontact metric structures.
Prevalence of eimeriosis in the one-humped camels (Camelus dromedarius) from Riyadh and Al-Qassim, Saudi Arabia
Authors: Metwally Dina M. , Al-Otaibi Tahani T. , Albasyouni Shurug A. , El-Khadragy Manal F. , Alajmi Reem A.
Published: November 2020

Background

The one-humped camels are economically important for several countries in Africa, Asia, and the Arabian Peninsula. Coccidiosis causes significant economic impact. Studies on coccidian parasite species causing such infections are limited. The present study aimed to carry out a survey ofEimeriaspp. in camels from Riyadh and Al-Qassim, Saudi Arabia.

Methods

A total of 209 fecal samples fromCamelus(C.)dromedariusslaughtered in West Abattoir in Riyadh and Onaizah Modern abattoir in Al-Qassim were collected. Samples were examined by flotation methods and oocyst sporulation.

Results

Of the 209 examined fecal samples, 75 were positive forEimeriaspp..The prevalence of oocysts in Riyadh and Al-Qassim were 33.89% (40/118) and 38.46% (35/92), respectively. The prevalence in young male camels was 41.02% (32/78) and 39.62% (21/53), respectively and in adult males was 19.35% (6/31) and 36% (9/25), respectively. Adult females displayed a prevalence of 22.22% (2/9) and 38.46% (5/13) in Riyadh and Al-Qassim, respectively. ThreeEimeriaspp. were identified;E. cameli,E. rajasthani, andE. pellerdyi. The presence ofE. pellerdyiis considered the first record in Saudi Arabia.
Factores que influyen en la implementación de una política pública de educación sexual integral: casos Chile y Costa Rica
Authors: Mella Robles Emanuel Franco , Rebolledo Toro Edgar Mauricio
Published: November 2020

El manuscrito aborda el problema de los resultados negativos que arrojan distintos indicadores sobre sexualidad y enfermedades de transmisión sexual en Chile. La comunidad LGBTIQ, género femenino, niños, niñas y adolescentes, por ser grupos vulnerables en materia de bienestar biopsicosocial y sexual, se ven especialmente afectados y representados por este problema y sus efectos. Las causas de base más importantes son las barreras culturales, de género y de acceso a la información. Por esto, el contar con una política de educación sexual integral (ESI) basada en estándares internacionales se propone como medio para solucionar el problema desde la raíz. El artículo analiza los factores que influyen en la implementación de la ESI como asunto público, mediante la revisión de la literatura y el estudio comparativo de los casos de Costa Rica y Chile, permitiendo inferir que el rol de los movimientos sociales feminista y LGBTIQ constituye un factor relevante.
Internacionalização do Ensino Superior no Brasil e no Chile: modelos parciais de adoção de normas internacionais
Authors: Souza Junior Jose Maria
Published: November 2020

Este trabalho compara o Ciência Sem Fronteiras no Brasil e o Becas Chile no Chile em relação às diretrizes para a internacionalização do Ensino Superior pela OCDE, UNESCO e BIRD. O Brasil preza pela centralização do sistema de ensino e o Ciência Sem Fronteiras incorpora elementos respaldados pelas organizações internacionais. O Chile tradicionalmente segue modelos de política criados externamente, mas tem no Becas Chile um exemplo de financiamento público. As diretrizes das organizações internacionais são implementadas parcialmente pelos Estados. A implementação parcial se dá de forma que normas locais pré-existentes e as normas internacionais entram em congruência e acham um solo comum para criarem novas normas e práticas, com importante influência de atores locais. As estruturas de ensino superior domésticas são influentes no processo de internacionalização dos dois países.
Resource Use Efficiency on Potato Farms in Azamgarh District of Eastern Uttar Pradesh, India
Authors: Yadav Ram Singh , Kushwaha R. R. , Maurya Kuldeep , Kumar Manoj , Yadav Bhartendu
Published: November 2020

The present study was carried out in Pawai block of Azamgarh district and five villages were selected randomly. A total number of 100 respondents were taken from the sleeted villages following the proportionate random sampling. The respondents were categorized as marginal (48), small (29) and medium (23) the data pertained to the agriculture year 2016-2017. The average holding size on overall farms was 1.553 ha and cropping intensity was 217.92 per cent. Cropping intensity was inversely related with the size of farms. The per farm average investment on overall farm came to Rs.242208.79 and maximum share was under the head of building i.e. 57.00 per cent followed by farm machinery and livestock share. The overall average cost of cultivation (C3) per hectare was Rs. 78154.62 and Gross income came to Rs. 123527.20, which offers a net income of Rs. 45372.50. Among the various resources considered under study the cost of seed showed significant relationship at 1 per cent level of probability in marginal category of farms and it was significantly associated at 5 per cent probability level in small and medium size group of farms. Another factor of production i.e. manures and fertilizer was found significantly associated with dependent variable at 1 per cent level probability in all farm situations. The sum of elasticity shows that potato cultivation was characterized as decreasing return to scale and positive value of marginal product indicate towards the further scope of expenditure on input to earn more than the cost. Problem related with hired human labour and technical knowledge were notice at 1st and 2nd rank by the sample farmers.
Performance of Maize (Zea mays [L.]) as Influenced by Row Arrangement and Cow dung Rates Grown in Intercrop with Watermelon (Citrullus lanatus [L.]) in Sudan Savanna
Authors: Dantata I. J. , Adam B. K. , Kabura B. H.
Published: November 2020

Field trials were carried out at the Teaching and Research Farm of Faculty of Agriculture, University of Maiduguri, Borno State, Nigeria during the 2014 and 2015 rainy seasons to study the performance of maize in maize/watermelon intercrop under varied row arrangements and cow dung rates in a Sudan Savanna Agro-ecology. The treatments consisted of factorial combinations of three row arrangements of maize: watermelon (1:1,1:2 and 2:1) and five levels of cow dung rates (0, 5, 10, 15 and 20t per ha) laid out in a split plot design and replicated three times. Cow dung was assigned to the main plots while row arrangements were assigned to the sub plots. The parameters of maize studied were: number of cobs per plant, cob length, cob diameter, 100 grain weight and grain yield per ha. The results showed that 1:2 row arrangement gave significantly greater cob diameter of maize. While 2:1 row arrangement gave significantly higher maize grain yield per ha. Application of 10t cow dung per ha to the mixture was found to be optimum for the maize grain yield per ha. The interaction or combination of 2:1 row arrangement and 10t cow dung per ha was optimum for the grain yield per ha. Based on the results of the present study, 2:1 row arrangement with application of 10t cow dung per ha should be adopted for growing of maize in intercrop with watermelon in the Sudan Savanna environment.
Serological and Molecular Characterisation of Virus Infecting Watermelon (Citrullus lanatus) in Adim-Biase, Cross River State, Nigeria
Authors: Eyong O. I. , Ekpiken E. E. , Ubi G. M. , Alobi A. O.
Published: November 2020

Watermelon, Citrullus lanatus, (Thunb.) is an annual crop in the Cucurbitaceae family grown for it fruits. It nutritional and medical uses helps in combating some illnesses and maintaining good health. The production of this crop in Nigeria is seriously under threat by virus disease. A survey of some farms in Adim, Biase Local Government Area of Cross River State, Nigeria during the 2019 planting season revealed mosaic and chlorotic symptoms. Mechanical inoculation was performed on young seedlings of Cucumeropsis mannii from watermelon samples showing viral symptoms and latter tested against the universal potyvirus antiserum and further detected by RT-PCR assay using cylindrical inclusion (CI) primer. The amplified cDNA was cloned and the nucleotide sequence determined. The serology result showed that there was positive reaction against the potyvirus antiserum confirming it to be a potyvirus. The gene sequence analysis revealed 86% sequence identity with Algerian watermelon mosaic virus. This is the first report of Algerian watermelon mosaic virus strain infecting watermelon in Nigeria.
Total Levels of Mercury Concentrations in Marine Fish - Kumasi, Ghana
Authors: Debrah Charles Afriyie- , Ribeiro Priscilla Francisco , Baah David
Published: November 2020

Fish is an excellent source of high biological value protein, is low in saturated fat, and contains polyunsaturated fatty acids and some vitamins. Mercury occurs naturally in the environment as a result of human activities. In aquatic environments, inorganic mercury is converted into methylmercury (the most common form of organic mercury) by microorganisms present in sediment through accumulations in the aquatic food chain, including in fish and shellfish. Fish absorb methyl mercury from water as it passes over their gills and as they feed on organisms. The objective of the study is to determine mercury pollution levels in fresh fish in Central Market, Kumasi, Ghana. A total of 42 fished were sampled randomly in separate labelled zip lock bags and stored in cold ice chest at different periods comparing of 27 different species after identification. Individual edible fish dorsal muscle tissue was taken and wet dried and analyzed using Cold Vapor Atomic Absorption Spectroscopy (CV-AAS) method which is really simple, accurate and rapid. The concentration of mercury in fish samples from the marine sea were determined with a mixture of HNO3, HClO4 and H2SO4 for complete oxidation of the organic tissue. The results showed that there was substantial amount of mercury in the fish samples ranged from 15.29 - 981.99 ng/g or ppb wet weight which is less than the FAO/WHO limits of 0.5 ppm wet weight. The study showed low concentrations of mercury in the fish species which do not appear to contribute any significant mercury exposure to the general population. It suggests that a relatively clean marine environment due to minimal industrial activity in the region that has not yet been significantly impacted by mercury contamination.
Application of Gamma Induced Mutation in Breeding Potato for Bacterial Wilt Disease Resistance
Authors: Chepkoech Emmy , Kinyua Miriam , Ochuodho Julius , Kiplagat Oliver , Bado Souleymane , Kinyua Zachary
Published: November 2020

Aims: Potato (Solanum tuberosum L.) production in Kenya has not been achieved in its full potential due to susceptibility of potato varieties to pest and diseases among others. Bacterial wilt, caused by Ralstonia solanacearum in potato is regarded as an important disease contributing to significant yield reduction. The disease is considered more difficult to control in field crop production using universal control measure due to pathogen’s properties as a soil-borne bacterium, broad host range and the genetic variation level within the strains. The objective was to screen potato mutants at M1V4 mutant populations for resistance against bacterial wilt using pathogenicity test.

Study Design: The experimental design used was an alpha lattice with twenty three blocks each having seven plots with three replications each. Data were subjected to analysis of variance using SAS statistical package, version 9.1 and mean separation done using Duncan Multiple Range Test (DMRT) whenever there were significant differences.

Place and Duration of Study: The study was carried out at Kenya Agricultural Livestock and Research Organization (KALRO), Kabete station for one season (December 2015 to April 2016).

Methodology: One hundred and sixty three mutants developed from three commercial varieties (Asante 72, Mpya 43 and Sherekea 47) were evaluated.

Results: The reactions of potato mutants to bacterial wilt varied from variety to variety and mutants to mutants. None of the Asante, Mpya and Sherekea mutants used was found to be resistant to bacterial wilt though Asante mutant populations showed better response. There was significant difference in some traits such as DTOW, AUDPC and PSTTN across the three potato mutant populations.

Conclusion: The variation within the potato mutants and response to bacterial wilt resistance levels could be attributed to different dose rates and the reaction of each variety to the mutagen used. Since mutation is random its effects are enormous.