bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of Natural Organic Matter by Nuclear Magnetic Resonance Spectroscopy
Authors: Leenheer Jerry A.
Published: November 2020

Natural organic matter (NOM) is a major intermediate in the global carbon, nitrogen, sulfur, and phosphorus cycles. NOM is also the environmental matrix that frequently controls binding, transport, degradation, and toxicity of many organic and inorganic contaminants. Despite its importance, NOM is poorly understood at the structural chemistry level because of its molecular complexity and heterogeniety. Nuclear magnetic resonance (NMR) spectroscopy is one of the most useful spectrometric methods used to investigate NOM structure because qualitative and quantitative organic structure information for certain organic elements can be generated by NMR for NOM in both the solution and solid states under nondegradative conditions. However, NMR spectroscopy is not as sensitive as infrared or ultraviolet-visible spectroscopy; it is not at present applicable to organic oxygen and sulfur, and quantification of NMR spectra is difficult under certain conditions. The purpose of this overview is to present briefly the “state of the art” of NMR characterization of NOM, and to suggest future directions for NMR research into NOM. More comprehensive texts concerning the practice of NMR spectroscopy and its application to NOM in various environments have been produced by Wilson and by Wershaw and Mikita. Carbon, hydrogen, and oxygen are the major elements of NOM; together they comprise about 90% of the mass. The minor elements that constitute the remainder are nitrogen, sulfur, phosphorus, and trace amounts of the various halogen elements. With the exception of coal, in which carbon is the most abundant element, the order of relative abundance in NOM on an atomic basis is H > C > O > N > S > P = halogens. The optimum NMR-active nuclei for these elements are 1H, 13C, 17O, 15N, 33S, 31P, and 19F. The natural abundances and receptivities of these nuclei relative to 1H are given in Table 12.1. Quadrupolar effects for 17O, 33S, and halogen elements other than 19F lead to line broadening that greatly limits resolution in NMR studies of these elements in NOM.
31P FT-NMR of Concentrated Lake Water Samples
Authors: Nanny Mark A. , Minear Roger A.
Published: November 2020

The use of phosphorus-31 Fourier Transform nuclear magnetic resonance (31P FT-NMR) spectroscopy for the study of dissolved organic phosphorus (DOP) in fresh water has been recently established by Nanny and Minear. The fact that NMR is an element-specific technique, is nondestructive, and has the ability to differentiate between similar phosphorus compounds makes it invaluable for the identification and characterization of DOP. Such information regarding DOP is required in order to understand aquatic nutrient cycling. The difficulty with using 31P FT-NMR spectroscopy for such studies is the extremely low DOP concentration; usually ranging from < 1 μg P/L in oligotrophic lakes to approximately 100 μg P/L for eutrophic systems. Nanny and Minear raised the DOP concentration into the NMR detection range, which is on the order of milligrams of phosphorus/liter, by concentrating large volumes of lake water with ultrafiltration (UF) and reverse osmosis (RO) membranes. Volume concentration factors of several ten thousand fold provided DOP concentrations of up to 60 mg P/L. Other DOP concentration methods such as anion exchange, lanthanum hydroxide precipitation, and lyophilization require severe chemical and/or physical transformations of the sample and/or they need long processing times, all of which increase the risk of DOP hydrolysis. Sample concentration with UF and RO membranes does not require the sample to undergo these major changes and is also a relatively rapid concentration method. In addition to these concentration capabilities, the use of ultrafiltration and reverse osmosis membranes permitted fractionation of the DOP samples according to molecular size. Nanny and Minear used three membranes in series with decreasing pore size: 30kDa (kilodaltons), 1 kDa, and RO (95% NaCl rejection) to separate the high-molecular-weight, intermediate-molecular-weight, and low-molecular-weight DOP species. In the intermediate-molecular-weight fraction, Nanny and Minear observed the presence of monoester and diester phosphates. Spectra from ten samples collected over a year typically consisted of a large broad signal in the monoester phosphate region spanning from a chemical shift of 2.00 ppm to −0.50 ppm. The maximum of this signal was usually in the range of 1.00 to 1.50 ppm. This broad signal had a shoulder in the diester phosphate region which sometimes was intense enough to appear as an individual signal.
Helping Children Learn to Make Responsible Choices
Authors: Polson Donene
Published: November 2020

As an OC teacher and parent, I have learned that making responsible choices is an ongoing process. A few years ago, I envisioned myself as “Supermom.” I made sure my son was getting his nutritious, low-sugar lunch, and I tried to anticipate anything that could come up by laying out his clothes, lunch, and sports equipment the night before. Or I would pack up my other three kids, ages one to five, and drive 20 minutes across town to bring my son his forgotten books, papers, lunches, or sports equipment. I did this at least twice a week. I was great! I gave myself the “Mother of the Year Award.” Then one day Mark’s first-grade OC teacher met me at the classroom door and asked me to consider letting Mark go without lunch the next time he forgot it. She gave me an article to read on teaching kids responsibility. She said that without his sack lunch, he would be forced to find other options; he could charge his lunch in the school cafeteria, or he could ask his friends for help. Could this possibly work? The next time he forgot his lunch, I stayed home and waited, just knowing that he was probably going to starve. However, when he came home he was fine and happy—all of his friends had shared their lunches with him! After that incident, he started putting his own things by the door and getting them ready to go for school. Another day he had to sit on the sidelines at the pool when he forgot his swimming suit. From then on, he remembered to take his own sports equipment. As I allowed my son to experience the logical consequences of his behavior, he learned to be more responsible. Helping children to make responsible choices in school begins with making sure that choices are available, then allowing children to learn from the logical consequences of their choices, with support from adults in reflecting on the process and results. Parents are sometimes concerned about the children’s use of time because so many choices are available in the OC.
Becoming a Cooperative Parent in a Parent Co-operative
Authors: Rogoff Barbara
Published: November 2020

Over the years that I spent as a co-oper for my three children in this parent co-operative school, I gradually came to understand the philosophy and become part of the structure of this learning community. It took a long time for me to grasp the underlying principles—the “common thread” that weaves through the practices of this community. An understanding of the principles gives participants a basis for knowing what to do, but at the same time, it seems that participating is essential for finding the principles. When I was a new co-oper, my career as a developmental psychologist was largely unrelated to my activities in the classroom. My choice to send my first child to the OC, over a decade ago, was based on the suggestion of a colleague in the psychology department at the University of Utah, who said, “Just think of all the research you can do in the OC!” and talked me into coming to visit his daughter’s classroom. At the time, although I liked what I saw for my daughter, I could see no way that I could make use of the OC as a research site—it didn’t connect with the way I was studying children’s learning. Over time, though, what I learned from the challenges of seeking this program’s principles of learning, in order to participate in it, has transformed my research and scholarly work. It opened my eyes to this way of thinking about learning, which I believe can contribute to advances in developmental and educational research and theory. The program philosophy is apparent in my 1990 book, Apprenticeship in Thinking, though at the time I wrote it I did not recognize the depth of its influence in my work. A key question that perplexed me as I struggled to understand how to participate in a community of learners, as a parent new to the OC, was how adults and children can collaborate in learning. This is a puzzle to many parents as they enter the program; it is also a classic issue in the fields of developmental psychology and education.
A Teacher Learning about Adult Learning
Authors: Mavor Denise Nelson
Published: November 2020

The approach of autumn puts me into a reflective mode, thinking about co-opers and their learning in their prior year in my classroom. One seems to be more relaxed about herself, her abilities, and her daughter’s. Another has really had great success with “I-messages” to handle problem solving in tense moments. I remember when a third didn’t really like a particular child; now look at them sitting together! I wish that I could have helped a fourth to understand my suggestions about how parents can be effective in the classroom. I inevitably end up with this final question: “How might I do things differently this year?” As a welcome breeze came through the west windows, blowing tenured milkweed seeds off the science shelf and into the classroom, I scanned the familiar circle of six-, seven-, and eight-year-olds and co-opers. I felt a warm smile growing on my face as my eyes lingered on Briand’s mother—I’ve been observing the confidence and patience Cindy has developed. She was sitting in circle, attentive to the children who had sighted the ghostly umbrella seeds suspended in air. The children had paused to inspect, capture, swat, and hail their arrival—loud enough to draw the entire class’s attention. “Cool!” “Don’t hit ‘em, you guys,” cautioned Keith. “They’re mine, remember? I brought them when school started.” “I caught one, Keith! Here, you can have it back,” Sarah said, modeling behavior for other classmates to follow. Circle was lively as the children caught the floating seeds and put them away. The last one landed on Cindy’s head. “There’s one in your hair, Mommy, I’ll get it.” Briand excitedly picked it from her mother’s hair and returned it to the science shelf. Cindy smiled through it all, having made progress in relaxing and enjoying the kids. . . . The Co-oping Commitment Develops into Conscious Co-oping . . . In August, when the teachers meet with the parent group to plan co-oping responsibilities, some parents who feel capable of teaching in a basic skills area, or at least feel adventurous, sign on to help teach one of those subjects.
Introduction
Authors: Farnham Nicholas H.
Published: November 2020

Liberal education has always had its full share of theorists, believers, and detractors, both inside and outside the academy. The best of these have been responsible for the evolutionary development of the concept of liberal education, for its changing tradition, and for the resultant adaptation of educational institutions to serve the needs of society. This book is the result of a meeting, primarily of believers, held at the American Academy of Arts and Sciences in Cambridge, Massachusetts, in April 1994. The reason for calling it was not simply to consider the unpleasant omens for liberal education that have been appearing as the end of a millennium is reached. A pessimist would include among them the end of the long period of economic growth for colleges, the decline of public support, the discovery that financial aid for tuition can be an Achilles' heel in times of rising costs, and the increasingly uncritical dependence of the public on the mass media and information technology, as well as a host of other external pressures and internal confusions. The meeting was called primarily to inspire further reflection on how liberal education can best continue to serve the healthy functioning of democratic society despite these apparent obstacles, for this concept still deserves a central pedestal in the educational pantheon. Presidents and chief academic officers of eighty liberal arts undergraduate institutions participated in the meeting, along with a dozen scholars and a few leaders of educational associations. Nine of the presentations from the symposium are included in this volume, accompanied by a statement prepared by all of the participants representing their general agreement about liberal education. The four-day symposium was sponsored by the Educational Leadership Program of the Christian A. Johnson Foundation and the American Council of Learned Societies. The Educational Leadership Program conducts research and seminars for college and school administrators. The American Council of Learned Societies supports scholarly research in the humanities.
Fourier Methods and Maximum Entropy Enhancement
Authors: Coppens Philip
Published: November 2020

Image formation in diffraction is no different from image formation in other branches of optics, and it obeys the same mathematical equations. However, the nonexistence of lenses for X-ray beams makes it necessary to use computational methods to achieve the Fourier transform of the diffraction pattern into the image. The phase information required for this process is, in general, not available from the diffraction experiment, even though progress has been made in deriving phases from multiple-beam effects. This is the phase problem, the paramount issue in crystal structure analysis, which also affects charge density analysis of noncentrosymmetric structures. For centrosymmetric space groups, the independent-atom model is a sufficiently close approximation to allow calculation of the signs for all but a few very weak reflections. Images of the charge density are indispensable for qualitative understanding of chemical bonding, and play a central role in charge density analysis. In this chapter, we will discuss methods for imaging the experimental charge density, and define the functions used in the imaging procedure. According to Eq. (1.22), the structure factor F(H) is the Fourier transform of the electron density ρ(r) in the crystallographic unit cell. The electron density p(r) is then obtained by the inverse Fourier transformation, or . . . ρ(r)=∫F(H) exp (−2πi H ·r) dH (5.1) . . . in which F(H) are the (complex) structure factors corrected for the anomalous scattering discussed in chapter 1.
Space Partitioning and Topological Analysis of the Total Charge Density
Authors: Coppens Philip
Published: November 2020

In partitioning space in the analysis of a continuous charge distribution, the requirement of locality, formulated by Kurki-Suonio (Kurki-Suonio 1968, 1971; Kurki-Suonio and Salmo 1971), should be preserved. It states that density at a point should be assigned to a center in the proximity of that point. In discrete boundary partitioning schemes, the density at each point is assigned to a specific basin, while in fuzzy boundary partitioning, the density at the point may be assigned to overlapping functions centered at different locations. The least-squares formalisms described in chapter 3 implicitly define a space partitioning scheme, based on the density functions used in the refinement that are each centered on a specific nucleus. Since the density functions are continuous, they overlap, so the fragments interpenetrate rather than meet at a discrete boundary. Such fuzzy boundaries correspond to smoothly varying functions, both in real and reciprocal space, and therefore to well-behaved fragment scattering factors, and reasonable fragment electrostatic moments. The interpenetratingfragment partitioning schemes are related to the Mulliken and Løwdin population analyses of theoretical chemistry. The topological analysis of the total density, developed by Bader and coworkers, leads to a scheme of natural partitioning into atomic basins which each obey the virial theorem. The sum of the energies of the individual atoms defined in this way equals the total energy of the system. While the Bader partitioning was initially developed for the analysis of theoretical densities, it is equally applicable to model densities based on the experimental data. The density obtained from the Fourier transform of the structure factors is generally not suitable for this purpose, because of experimental noise, truncation effects, and thermal smearing. The topological analysis of the density leads to a powerful classification of bonding based on the electron density. It is discussed in the final sections of this chapter. The stockholder partitioning concept is one of the important contributions to charge density analysis made by Hirshfeld (1977b). It defines a continuous sampling function wi(r), which assigns the density among the constituent atoms. The sampling function is based on the spherical-atom promolecule density—the sum of the spherically averaged ground-state atom densities.
The Tribulations of the Thirties
Authors: Gleason Philip
Published: November 2020

Relations between Catholic institutions and the North Central Association (NCA) played a key role in the organizational strains that developed in the early 1930s. As we saw in Chapter 2, the example set by this pacesetter among the regional accrediting associations contributed importantly to the NCEA’s launching into the work of accreditation. Pioneering Catholic reformers like James A. Burns, C.S.C., and Albert C. Fox, S.J., had close ties with the North Central, a tradition carried further by later progressives like William F. Cunningham, C.S.C., who was appointed to its board of review in 1926, and Alphonse M. Schwitalla, S.J., who served as its president ten years later. The North Central welcomed Catholic involvement. After all, Catholic schools constituted a significant proportion of its clientele, so it made good organizational sense to cultivate friendly relations with Catholic educators. Besides, as Raymond M. Hughes, president of Miami University (Ohio) and a leading figure in the North Central, pointed out in 1926, the accrediting standards being used by the NCEA were “practically identical” with those of the NCA. This suggested the desirability of closer cooperation between the two bodies, especially in dealing with problems distinctive to Catholic institutions. The example Hughes cited to illustrate this kind of problem was the difficulty NCA inspectors had in evaluating the “educational backgrounds” of faculty members who were members of religious communities. This was in one sense a mark of recognition, but it was linked to something less reassuring to Catholics—the North Central’s steadily rising expectations about the amount and quality of graduate training college faculty members should have. The NCA did not evaluate graduate programs as such, but it was very much interested in the professional competence of faculty members, and that was rated in terms of the graduate training they had received. As more Catholic schools began offering advanced work, the NCA felt some concern about its quality, especially since so many faculty members at Catholic colleges took their graduate degrees from other Catholic institutions.
Assimilative Tendencies and Curricular Crosscurrents
Authors: Gleason Philip
Published: November 2020

Besides its massive impact on the institutional side of Catholic higher education, World War II affected the thinking of Catholic educators. We have already touched upon this dimension in noting how the war and postwar growth required them to expand their horizons and redouble their efforts in research, fundraising, and administration generally. Here we look more closely at how Catholics were affected by the great ideological revival of democracy that accompanied the war. This kind of influence was sometimes explicitly noted by Catholic leaders, as when Archbishop Richard Gushing of Boston called attention to the “neo-democratic mentality of returning servicemen and the university-age generation generally”; others recognized that it created problems since the Catholic church was so widely perceived as incompatible with democracy and “the American way of life.” We shall postpone examination of controversies stemming from this source to the next chapter, turning our attention in this one to the assimilative tendencies reflected in Catholics’ new appreciation for liberal democratic values, and to the major curricular concerns of the era which were also affected by the war. In no area did the democratic revival have a more profound long range effect than in the impetus it lent to the movement for racial equality and civil rights for African Americans. The publication in 1944 of Gunnar Myrdal’s An American Dilemma marked an epoch in national understanding of what the book’s subtitle called “the Negro problem and modern democracy.” Myrdal himself stressed the importance of the wartime context, which made it impossible to ignore racial discrimination at home while waging war against Nazi racism. At the same time, increasing black militance, the massive migration of African Americans to northern industrial centers, and above all the great Detroit race riot of 1943—reinforced by the anti-Mexican “Zoot Suit” riots in Los Angeles the same summer—suddenly made the improvement of race relations an imperative for American society as a whole. By the end of the war, no fewer than 123 national organizations were working actively to “reduce intergroup tensions,” and the civil rights movement began a steady advance that led directly to the great judicial and political victories it won in the fifties and sixties.
The Molecular Electrostatic Potential: A Tool for Understanding and Predicting Molecular Interactions
Authors: Murray Jane S. , Politzer Peter
Published: November 2020

The quest for improved methods for elucidating and predicting the reactive behavior of molecules and other chemical species is a continuing theme of theoretical chemistry. This has led to the introduction of a variety of indices of reactivity; some are rather arbitrary, while others are more or less directly related to real physical properties. They have been designed and are used to provide some quantitative measure of the chemical activities of various sites and/or regions of the molecule. In this chapter our focus is on one of these indices, the electrostatic potential V(r) that is created in the space around a molecule by its nuclei and electrons. V(r) can be computed rigorously, given the electronic density function ρ(r), by Eq. (3.1).
Applications of Density Functional Theory to Biological Systems
Authors: Wesolowski Tomasz Adam , Weber Jacques
Published: November 2020

The term biological systems may be used in reference to a wide class of polyatomic systems. They can be defined as minimal functional units which perform specific biological functions: enzymatic reactions, transport across membranes, or photosynthesis. At present, such systems as a whole are not amenable to quantum-chemistry studies because of their large size. The smallest enzymes are built of few thousands of atoms (e.g., lysozyme consists of 129 amino-acid subunits), the smallest nucleic acids are of similar size (e.g., t-RNA molecules consist of about 80 nucleotide subunits), whereas biological membranes are even larger and include different biological macromolecules embedded in a phospholipide medium. On the other hand, a common-sense definition of the term biological systems refers to any chemical molecule or molecular complex which is involved in biological or biochemical processes. The latter definition, which will be used throughout this review, covers not only complete functional units performing biological functions but also fragments of such units. Theoretical studies have provided data on properties of such fragments and have helped understanding of the biological processes at the molecular level. Depending upon the size of such fragments, they can be studied by means of various quantum-chemical methods. Molecular systems of up to a few thousands of atoms can be studied using semi-empirical methods. For the Hartree-Fock or Kohn-Sham density functional theory (DFT) calculations, the current size limit is a few hundreds of atoms. (Throughout the text, Hartree-Fock refers to ab initio Self-Consistent Field calculations using the approximation of linear combination of atomic orbitals.) When the desired accuracy requires the calculation of electron correlation at the ab initio level, only systems containing no more than few tens of atoms can be treated. Therefore, a theoretician aiming at the elucidation of biological processes by quantum-mechanical calculations faces two crucial issues. The first one is the selection of a fragment for modeling at the quantum-mechanical level. The second one is the assessment of the effects associated with parts of the system which cannot be modeled at the quantum-mechanical level. In this review, the DFT studies of biological systems are divided into two groups corresponding to different ways of addressing the second aforementioned issue.
On Comparing Experimental and Calculated Structural Parameters
Authors: Schäfer Lothar , Ewbank John D.
Published: November 2020

The tacit assumption underlying all science is that, of two competing theories, the one in closer agreement with experiment is the better one. In structural chemistry the same principle applies but, when calculated and experimental structures are compared, closer is not necessarily better. Structures from ab initio calculations, specifically, must not be the same as the experimental counterparts the way they are observed. This is so because ab initio geometries refer to nonexistent, vibrationless states at the minimum of potential energy, whereas structural observables represent specifically defined averages over distributions of vibrational states. In general, if one wants to make meaningful comparisons between calculated and experimental molecular structures, one must take recourse of statistical formalisms to describe the effects of vibration on the observed parameters. Among the parameters of interest to structural chemists, internuclear distances are especially important because other variables, such as bond angles, dihedral angles, and even crystal spacings, can be readily derived from them. However, how a rigid torsional angle derived from an ab initio calculation compares with the corresponding experimental value in a molecule subject to vibrational anharmonicity, is not so easy to determine. The same holds for the lattice parameters of a molecule in a dynamical crystal, and their temperature dependence as a function of the molecular potential energy surface. In contrast, vibrational effects are readily defined and best described for internuclear distances, bonded and non-bonded ones. In general, all observed internuclear distances are vibrationally averaged parameters. Due to anharmonicity, the average values will change from one vibrational state to the next and, in a molecular ensemble distributed over several states, they are temperature dependent. All these aspects dictate the need to make statistical definitions of various conceivable, different averages, or structure types. In addition, since the two main tools for quantitative structure determination in the vapor phase—gas electron diffraction and microwave spectroscopy—interact with molecular ensembles in different ways, certain operational definitions are also needed for a precise understanding of experimental structures. To illustrate how the operations of an experimental technique affect the nature of its observables, gas electron diffraction shall be used as an example.
The Market: Physical Aspects
Authors: Sperber Daniel
Published: November 2020

One of the most distinctive features of the urban landscape in antiquity was undoubtedly the marketplace or, more exactly, the market area. In Roman Palestine this at times was organized around a large open space surrounded by colonnades with buildings containing shops and stalls or booths between the columns, much as in a Roman forum. Here people came from villages to sell their wares, perhaps bringing them on a donkey laden with panniers, while the locals sat comfortably in their permanent locations and plied their trades.
Pubs, Drunkards, and Licensing Laws
Authors: Sperber Daniel
Published: November 2020

We now move on from the marketplace to the pubs and drinking houses, which as we have already seen, were to be found in the periphery of the market area. Here again we shall see that at times a brief homily in a Midrash can give us a glimpse into social situations in Roman Palestine; when coupled with classical sources, these homilies can help create a picture of how society functioned in that period. I will begin with a passage from Leviticus Rabba, which although it has the hallmarks of a sermon and therefore may not be strictly accurate historically, nonetheless captures the feeling of the times and is thus most instructive to the historian. In order fully to understand this text, we must first preface our discussion with some introductory remarks. The problem of Roman sumptuary laws has been discussed by a number of scholars. Ramsay MacMullen in his Enemies of the Roman Order has written as follows: . . .From the 70’s A.D., the governing classes, heavy eaters themselves and sometimes, like Nero, addicts of dives and bars, tried to improve the character of the lower classes by intermittent legislation to shut up taverns and to prohibit the sale of cooked meats and pastries. That left vegetables, their definition at one time being narrowed to peas and beans. After Vespasian, public morals were given up as a bad job for three centuries. In the 370’s, when prefects renewed the war, they limited wine shops in what they could sell and in the hours they could stay open. . . . Of particular importance in this connection is the statement of Ammianus Marcellinus that Ampelius, governor of Rome (371-72 C.E.), gave orders that no wine shop should be opened before the fourth hour (about nine o’clock in the morning), in other words, that wine shops should be shut up at night. It is clear from these examples that an examination of pubs and licensing hours can offer valuable insights into social conditions of the time.
Archeology and the City,
Authors: Schwartz Joshua J.
Published: November 2020

The complexities of city life in the Roman period and the rich varieties of urban existence during that time have not always been revealed by the spade of the archeologist. Much mentioned in the literary sources of the time has not been uncovered in archeological excavations and even when perchance it has been, it has not always been correctly identified. In any case, the limitations of present-day research often make such identification all but impossible. For example, literary sources, both Jewish and non-Jewish, mention buildings or monuments in Late Roman period Caesarea. We know, however, very little about what this city or the buildings in it looked like. Moreover, there are dozens of unidentified “public buildings” that have been uncovered in the course of archeological excavations that await some shred of additional information or keen analysis to determine or to corroborate their purpose or function. Thus, it would be the lucky archeologist who would discover and excavate a tavern (kapelia) or a prison, for instance, in one of the Roman-period cities of the Land of Israel. And even if by chance he did discover a structure that fulfilled one of these functions, it is doubtful that he would ever really be able to prove it. Moreover, Roman-period cities were built to accentuate the public aspects of city life, and this type of building did not always tell the full story of urban life. Interurban competition and the occasional economic windfall often resulted in spurts of public building activity of a monumental and elaborate nature. There was often more form than substance behind this type of building, and occasionally this form was more vain, sterile, and ostentatious than the actual life of the city. The archeologist by nature, however, gravitates toward excavation of the grand. It is the public life of cities that archeologists try to reveal, and even this might be more fleeting than they are willing to admit. The more private aspects of urban existence often remain hidden or within the realm of the historian, not the archeologist.
Introduction
Authors: Bäck Thomas
Published: November 2020

The conversation between Alice and the Cat gives a perfect characterization of the meandering path full of dead ends, sharp curves and hurdles one has to follow when doing research. After three and a half years, my first section of this path through wonderland ends up with the work presented here. In its final form, it deals with Evolutionary Algorithms (for parameter optimization purposes) and puts particular emphasis on extensions and analysis of Genetic Algorithms, a special instance of this class of algorithms. The structure of this research, however, has grown over the years and is just slightly related to Classifier Systems, the original starting point of my work. These contain Genetic Algorithms as a component for rule-discovery, and as Classifier Systems turned out to lack theoretical understanding almost completely, the concentration of interest on Genetic Algorithms was a natural step and provided the basis of this work. The book is divided into two parts that reflect the emphasis on Genetic Algorithms (part II) and the general framework of Evolutionary Algorithms that Genetic Algorithms fit into (part I). Part I concentrates on the development of a general description of Evolutionary Algorithms, i.e. search algorithms gleaned from organic evolution. These algorithms were developed more than thirty years ago in the “ancient” times of computer science, when researchers came up with the ideas to solve problems by trying to imitate the intelligent capabilities of individual brains and populations. The former approach, emphasizing an individual’s intelligence, led to the development of research topics such as artificial neural networks and knowledge-based symbolic artificial intelligence. The latter emphasized the collective learning properties exhibited by populations of individuals, which benefit from a high diversity of their genetic material. Modeling organic evolution provides the basis for a variety of concepts such as genotype, genetic code, phenotype, self-adaptation, etc., which are incorporated into Evolutionary Algorithms. Consequently, the necessary prerequisites to understand the relations between algorithmic realizations and biological reality are provided in chapter 1. In addition to this, chapter 1 clarifies the relationship between global random search algorithms and Evolutionary Algorithms, Artificial Intelligence and Evolutionary Algorithms, and computational complexity and Evolutionary Algorithms.
Selection
Authors: Bäck Thomas
Published: November 2020

The genetic operators summarized in the set Ω, i.e. mutation and recombination (and probably others, e.g. inversion) create new individuals in a completely undirected way. In Evolutionary Algorithms, the selection operator plays a major role by imposing a direction on the search process, i.e. a clear preference of those individuals which perform better according to the fitness measure Φ. Selection is the only component of Evolutionary Algorithms where the fitness of individuals has an impact on the evolution process. The practical implementations of selection as discussed in sections 2.1.4, 2.2.4, and 2.3.4 seemingly contradict the biological viewpoint presented in section 1.1, where natural selection was emphasized not to be an active force but instead to be characterized by different survival and reproduction rates. However, artificial implementation models and biological reality are not necessarily contradicting each other. While in biological systems fitness can only be measured indirectly by differences in growth rates, fitness in Evolutionary Algorithms is a direct, well-defined and evaluable property of individuals. The biological struggle for existence (e.g. by predator-prey interactions, capabilities of somatic adaptation, and the particular physical properties of individuals) has no counterpart in computer implementations of standard Evolutionary Algorithms. Therefore, an artificial abstraction of these mechanisms can use fitness measures to determine survival and reproduction a posteriori, since the struggle for existence is completely hidden in the evaluation process of individuals. The fact that different survival and reproduction constitute selection is valid in both cases, but in Evolutionary Algorithms fitness is measurable and implies the survival and reproduction behavior, which is just opposite to biological reality. This is simply an implication of the fitness-centered intention which necessarily prevails design and application of these algorithms. Therefore, it is just a logic consequence to model selection as an active, fitness-based component of Evolutionary Algorithms. However, how to model selection is by no means a simple problem. In evolutionary biology, it is usually distinguished between stabilizing, directed, and disruptive selection (see [Fut90], pp. 174–175). In the case of stabilizing selection, intermediate phenotypes have best fitness values, while disruptive selection is characterized by two or more distinct phenotypes that are highly fit and by intermediate phenotypes of low fitness (this assumes an - albeit unknown - ordering of phenotypes).
Random Processes and Fields
Authors: Polyak Ilya
Published: November 2020

In this chapter, the nonparametric methods of estimating the spectra and correlation functions of stationary processes and homogeneous fields are considered. It is assumed that the principal concepts and definitions of the corresponding theory are known (see Anderson, 1971; Box and Jenkins, 1976; Jenkins and Watts, 1968; Kendall and Stuart, 1967; Loeve, 1960; Parzen, 1966; Yaglom, 1986); therefore, only questions connected with the construction of numerical algorithms are studied. The basic results ranged from univariate process to multidimensional field are presented in Tables 3.1 and 3.2. These formulas make it possible to compare and trace the formal character of developing estimation procedures when the dimensionality is increasing. The schemes in these tables, as well as the formulas in the previous chapters, can be used for software development without any rearrangement. In part, this approach presents the application of the methods of Chapters 1 and 2 in evaluating random function characteristics. Of course, the final identification of the algorithm parameters (for example, the spectral window widths) can be made only through trial and error and by taking into account the character of the problem under study, that is, the physical properties of the processes and fields observed. The last section of this chapter presents results of the application of these methods to the analysis of some climatological fields. Here the basic results of the univariate spectral analysis are briefly discussed in order to develop algorithms for a multidimensional case by analogous reasoning. The complete description of the estimation procedures of the spectral and correlation analysis for univariate stationary process can be found, for example, in Jenkins and Watts, 1968.
Fundamentals of Nonlinear Optimization
Authors: Floudas Christodoulos A.
Published: November 2020

This chapter discusses the fundamentals of nonlinear optimization. Section 3.1 focuses on optimality conditions for unconstrained nonlinear optimization. Section 3.2 presents the first-order and second-order optimality conditions for constrained nonlinear optimization problems. This section presents the formulation and basic definitions of unconstrained nonlinear optimization along with the necessary, sufficient, and necessary and sufficient optimality conditions. An unconstrained nonlinear optimization problem deals with the search for a minimum of a nonlinear function f(x) of n real variables x = (x1, x2 , . . . , xn and is denoted as Each of the n nonlinear variables x1, x2 , . . . , xn are allowed to take any value from - ∞ to + ∞. Unconstrained nonlinear optimization problems arise in several science and engineering applications ranging from simultaneous solution of nonlinear equations (e.g., chemical phase equilibrium) to parameter estimation and identification problems (e.g., nonlinear least squares).
The Killer Strikes
Authors: Verschuur Gerrit L.
Published: November 2020

At the beginning of the nineteenth century, French paleontologist Baron Georges Cuvier recognized that many fossils represented the remains of species that no longer roamed the earth but were only to be found in certain rock strata. To convey what this discovery meant, he painted a vivid picture. “Life on earth,” he wrote, “has been frequently interrupted by frightful events.” A modern commentator, Derek Ager, likened the tale revealed by the fossil record to that of the life of a soldier: “Long periods of boredom and short periods of terror.” The periods of “boredom” are what we experience for most of our lives, when all is well with the world. That is the way we like it. The climate is benign and the seasons come and go in an endless and reassuringly predictable procession, and we survive nicely without being threatened by nature. Sometimes the spell is broken by a catastrophe; a tornado ripping at our house, a flood washing it away, or fire engulfing all in its path. After the terror has passed, all is peaceful again. Sixty-five million years ago a catastrophe of awesome proportions struck our planet. Something happened to wipe out the dinosaurs as well as about 60 percent of all species that lived at the time. After a century or more of sifting through incriminating evidence left at the scene of the crime, scientists have at last identified a comet or asteroid colliding with earth as the killer. The victims of this headlong collision on earth were felled by the devastating explosion of impact or killed in its aftermath. The comet impact of 65 million years ago was not the first of its kind, nor will it be the last. To appreciate how serious the danger is, let’s start with the dinosaurs. Their history has slowly and laboriously been pried from ancient rock and clay layers in which fossils are preserved. Fossilization happens to plants and animals whose remains sink into the muddy sediments at the bottom of oceans, seas, lakes, rivers, and streams where they are preserved in what will later become layers of rock.
Something about Comets
Authors: Verschuur Gerrit L.
Published: November 2020

Discovery of the iridium layer in the K/T boundary clay was the first clue that pointed to a cosmic impact as the trigger of the mass extinction that wiped out the dinosaurs and their associates. But what hit the earth? Was it an asteroid or a comet? To answer, we need to know something about their differences. Unfortunately, the distinction is very blurred. Comets are thought to be huge icy objects, probably with cores made of a mix of water ice and silicates (sandy material), pristine examples of the type of material out of which the solar system was formed. Some of them are hundreds of kilometers in size and they may have been built in the envelopes of gas and dust that surround cool, supergiant stars at the end of their lives. Part of the doubt about distinctions comes from trying to decide what a comet would be like after the ice evaporates. Would it then be like an asteroid? Around the end of the nineteenth century the British astronomer Sir Richard Gregory pictured comets as made up of a cloud of meteorites. He thought that when such an object was first pulled into the solar system from interstellar space it began to glow because of internal heat created as particles began to jostle one another. As the object drew closer to the sun a tail was supposed to be formed as the particles between the meteorites bumped into one another and began to escape. He did consider the potential risk to earth if it were to run into the head of a comet made up of lots of meteorites. The picture he painted was based on what an earlier astronomer, Sir Simon Newcomb, had written about this possibility. Newcomb admitted that, although there were more likely ways to die than as a result of comet collision, such a fate was real. Should such a collision, occur, Gregory conjured up a picture of what might happen. On the one hand, if the comet head was made up of dust, the earth’s inhabitants would experience nothing more than a stunning display of shooting stars. But if the comet head was made of cannonball sized objects the consequences would be dire.
Craters and Tsunamis
Authors: Verschuur Gerrit L.
Published: November 2020

Until the lunar explorations began in earnest in the 1960s, the Barringer crater in Arizona was believed to be one of the few, if not the only, impact crater on earth. Before the moon landings, many scientists thought that lunar craters were volcanic in origin and that the moon might be covered in a layer of volcanic dust meters thick so that astronauts would sink up to their eyeballs when disembarking from their space capsules. A pleasant sense of relief greeted the news that the first unmanned lunar spacecraft did not disappear into the dust. For a century or more it was doubted that lunar craters were produced by impacts because it was assumed that such craters would seldom be circular. It seemed obvious that circular craters could only be produced by objects falling straight down, a rare situation, since meteorites are likely to approach from random directions, especially on the moon where there is no atmosphere to slow them down before impact. W. M. Smart in 1928 stated this explicitly: “Objections to lunar craters being caused by meteors is that the craters are round and there is no a priori reason why meteors should fall vertically and in no other direction.” He also shuddered at the notion that the impactors would have to be as large as asteroids to create the lunar basins. At about the same time, Thomas Chamberlin ruled out impacts on the moon because there was no evidence for an appropriate population of objects anywhere in the solar system that could have made the craters That was in 1928 when near-earth asteroids had not yet been found, and when little was known about the history of the moon or the formation of the solar system. Richard A. Proctor in 1896, however, had concluded that because so many meteors continued to fall to earth that the planet and the solar system were still forming. To him, this made more sense than to blame the formation of the planets on “the creative fiats of the Almighty.” There is merit to his point of view, because today’s bombardment merely represents a faint, ongoing manifestation of the process of accretion that assembled the planets in the first place.