bluuebunny/crossref_metadata_2025_split huggingface dataset:
New reactions of functionalized β-lactams
Authors: Van Brabandt Willem , Dejaegher Yves , De Kimpe Norbert 
Published: December 2005

Abstract
An easy synthesis of 4-(1- and 2-haloalkyl)azetidin-2-ones by a [2+2] cycloadditon protocol is described. Starting from these functionalized β-lactams, new pathways toward bicyclic β-lactams were developed via intramolecular nucleophilic substitutions and radical cyclizations. 4-(1- and 2-Haloalkyl)azetidin-2-ones also proved to be very useful starting products in the synthesis of various highly substituted aziridines, azetidines, and alkenoates.
From vinylsilanes to organic/inorganic hybrid materials
Authors: Luh Tien-Yau 
Published: December 2005

Abstract
Alternating regioregular silylene-spaced divinylarene copolymers [(donor-SiMe2-)
n

=1-3-(acceptor-SiMe2)] are synthesized by rhodium-catalyzed hydrosilylation of bis-alkynes with bisvinylic silyl hydrides. Efficient intrachain energy transfer has been observed in these copolymers. The intensities of emission profiles depend on the relative ratio of donor-to-acceptor chromophores. The corresponding inorganic/organic hybrid materials are synthesized, and their photophysical properties are described.
Asymmetric cyclopropanation of chiral (1-phosphoryl)vinyl sulfoxides: A new approach to constrained analogs of biologically active compounds
Authors: Mikołajczyk Marian 
Published: December 2005

Abstract
This account outlines the results obtained in the author's laboratory on the asymmetric cyclopropanation of enantiopure 1-phosphorylvinyl p-tolyl sulfoxides with sulfur ylides and diazoalkanes. Based on experimental results and theoretical calculations, the transition-state model for asymmetric cyclopropanation is proposed. A great synthetic value of the reaction investigated is exemplified by the total synthesis of constrained analogs of bioactive compounds, namely, enantiopure cyclic analog of phaclofen and cyclopropylphosphonate analogs of nucleotides.
Chiral phosphine Lewis bases in catalytic, asymmetric aza-Morita-Baylis-Hillman reaction
Authors: Shi Min , Chen Lian-Hui 
Published: December 2005

Abstract
In the aza-Morita-Baylis-Hillman reaction of N-sulfonated imines with methyl vinyl ketone (MVK) promoted by chiral phosphine Lewis base: (R)-2'-diphenylphosphanyl-[1,1']binaphthalenyl-2-ol (LB1) (10 mol %), the aza-Morita-Baylis-Hillman adducts were obtained in good yields with high ee (70-94 % ee) at -30 °C in THF. The scope and limitations of this reaction have been disclosed.
Enantioselective addition of organozinc reagents to carbonyl compounds
Authors: Yus Miguel , Ramón Diego J. 
Published: December 2005

Abstract
Different chiral camphorsulfonamide derivatives containing a hydroxy or a sulfonamido functionality, as well as chiral 1,2-hydroxysulfonamides, have been evaluated as chiral promoters in the classical enantioselective addition of dialkylzinc reagents to aldehydes in the presence of titanium tetraisopropoxide (ee up to 96 %). Surprisingly, ligands with a structure of isoborneol are able to promote the related unknown addition to ketones (ee >99 %), the best ligand being the exo-diol derived from 1,2-trans-biscamphorsulfonamidocyclohexane (HOCSAC).
Supramolecular assemblies with DNA* (Special Topic Article)
Authors: Barthélémy Philippe , Lee Stephen J. , Grinstaff Mark 
Published: December 2005

Abstract
Information storage in chemical and biological systems involves recognition processes occurring at the molecular and macromolecular level. The implementation of a "code" can consist of multiple noncovalent interactions, which include hydrogen bonds, π-stacking, hydrophobic interactions, and appropriate molecular and supramolecular architectures. With the double-helical DNA structure stabilized by Watson-Crick hydrogen bond base-pairing and aryl π-π stacking interactions, nature provides to scientists an example of one of the most sophisticated supramolecular systems. Molecular organization using these types of processes has become a very powerful strategy for the construction of well-defined nanostructures. Self-assemblies using noncovalent interactions have been designed to build fibers, membranes, two-dimensional monolayers, hydro, organo gels, etc. This paper highlights the research presented at the workshop entitled DNA Supramolecular Assemblies, which was held in Avignon, France on 5-6 May 2004. In this article, we first focus on the recent progress achieved in the design of supramolecular self-assemblies that mimic the molecular recognition functionalities found with nucleic acids. Second, we present several synthetic-DNA supramolecular assemblies currently developed to transport nucleic acids into cells. The marriage of supramolecular chemistry with nucleic acids as illustrated through examples in this article will open new avenues for designing artificial molecular devices and expand the current repertoire of supramolecular assemblies available.
Atomic force microscopy and direct surface force measurements (IUPAC Technical Report)
Authors: Ralston John , Larson Ian , Rutland Mark W. , Feiler Adam A. , Kleijn Mieke 
Published: December 2005

Abstract
The atomic force microscope (AFM) is designed to provide high-resolution (in the ideal case, atomic) topographical analysis, applicable to both conducting and nonconducting surfaces. The basic imaging principle is very simple: a sample attached to a piezoelectric positioner is rastered beneath a sharp tip attached to a sensitive cantilever spring. Undulations in the surface lead to deflection of the spring, which is monitored optically. Usually, a feedback loop is employed, which holds the spring deflection constant, and the corresponding movement of the piezoelectric positioner thus generates the image. From this it can be seen that the scanning AFM has all the attributes necessary for the determination of surface and adhesion forces; a sensitive spring to determine the force, a piezoelectric crystal to alter the separation of the tip and surface, which if sufficiently well-calibrated also allows the relative separation of the tip and surface to be calculated. One can routinely quantify both the net surface force (and its separation dependence) as the probe approaches the sample, and any adhesion (pull-off) force on retraction. Interactions in relevant or practical systems may be studied, and, in such cases, a distinct advantage of the AFM technique is that a particle of interest can be attached to the end of the cantilever and the interaction with a sample of choice can be studied, a method often referred to as colloid probe microscopy. The AFM, or, more correctly, the scanning probe microscope, can thus be used to measure surface and frictional forces, the two foci of this article. There have been a wealth of force and friction measurements performed between an AFM tip and a surface, and many of the calibration and analysis issues are identical to those necessary for colloid probe work. We emphasize that this article confines itself primarily to elements of colloid probe measurement using the AFM.
Critical Investigations of Age and Aging in the United States
Authors: LAMB SARAH E. 
Published: December 2005

Aged by Culture. Margaret Morganroth Gullette. Chicago: University of Chicago Press, 2004. 267 pp. Breaking the Watch: The Meanings of Retirement in America. Joel S. Savishinsky. Ithaca, NY: Cornell University Press, 2000. 281 pp. My Mother's Hip: Lessons from the World of Eldercare. Luisa Margolies. Philadelphia: Temple University Press, 2004. 339 pp.
Indigenous Peoples, State‐Sanctioned Knowledge, and the Politics of Recognition
Authors: RANCO DARREN J. 
Published: December 2005

Invisible Indigenes: The Politics of Nonrecognition. Bruce G. Miller. Lincoln: University of Nebraska Press, 2003. 248 pp. Forgotten Tribes: Unrecognized Indians and the Federal Acknowledgement Process. Mark Edwin Miller. Lincoln: University of Nebraska Press, 2004. 355 pp. Gambling and Survival in Native North America. Paul Pasquaretta. Tucson: University of Arizona Press, 2003. 202 pp.
Music and Late Elizabethan Politics: The Identities of Oriana and Diana
Authors: SMITH JEREMY L. 
Published: December 2005

Abstract
This essay challenges the current assessment that Thomas Morley's collection, The Triumphes of Oriana, was an uncomplicated musical tribute to Queen Elizabeth I, who was represented allegorically by Oriana, heroine of the romance Amadis de Gaule. It takes into account both the political context surrounding the Essex Revolt, the Elizabethan succession question, and the Catholic issue and the ideas reflected in the poetry that was set to music, as well as some of the music itself. It can be shown that both Morley and his mentor William Byrd were strongly linked to the Sidney/Essex complex of ideals that had a special appeal to Catholics who hoped for a more tolerant regime and who looked to Essex and a Jamesian succession as possible vehicles of salvation. Demonstrating the unsuitability of the Oriana characterization for Elizabeth, I propose a different allegorical identity not only for “Oriana” (James's wife Anna) but also for the character “Diana” (Essex's sister Penelope Rich), who appears in key works by Byrd and in all the Oriana madrigals as well. Certain songs by Byrd promoted the ideas of Sidney and his circle as well as Essex's image as the “heir to Sir Philip Sidney.” Morley's project for the Triumphes began originally, evidence shows, as a musical offering pleasing to the Essex camp and supportive of James's succession. A marked shift in political circumstances between 1600 and 1601 made it incumbent upon Morley and his collaborators to pay tribute to Elizabeth instead, but not all traces of the original intent were effaced. The ambivalence in the meaning of the Oriana and Diana allegories continued into the post-Elizabethan era.
The Beloved's Image: Handel's Admeto and the Statue of Alcestis
Authors: HELLER WENDY 
Published: December 2005

Abstract
This essay offers a new interpretation of Handel's Admeto (1727) in the context of its literary and operatic antecedents. Focusing on the erotic triangle between the lover, the beloved, and the image of the beloved—a “fundamental story” expressed in its paradigmatic form in Euripides' play Alcestis—the essay demonstrates the unexpected ways in which Handel's opera—and its Venetian and Hannoverian predecessors—absorbed the residue of the Euripidean tradition, reconciling fundamental truths about lovers and their beloveds with early modern customs and ways of thinking about art, theater, and life. It takes account of the special importance that this libretto had for the Hannoverian dynasty (in particular Electress Sophia, consort of Ernst August, the father of George I), exploring as well how one of opera's most ubiquitous props—the portrait—reflected an early modern fascination with the power of simulacra to substitute for living beings. In this context, the oft-criticized conventions of Venetian opera that were retained by Handel—including not only the use of the portrait, but transvestism and a double-woman plot—emerge as part of a seicento sensibility that was not only embraced by the Venetians and the Hannoverians, but was integral to the dramatic vision expressed in Admeto. In so doing, the essay provides not only a new account of Admeto's rapport with the ancients, but also a more nuanced account of Handel's debt to the Venetian legacy.
A Minstrel in a World without Minstrels: Adorno and the Case of Schreker
Authors: LEE SHERRY D. 
Published: December 2005

Abstract
Franz Schreker (1878–1934) was widely regarded during the height of his career as a daringly modern and controversial composer. The tremendous initial popularity of his operas gave no forewarning of the virtual oblivion to which their composer would be consigned by history. Theodor W. Adorno's 1959 essay on Schreker recalls the composer's importance on the early modernist scene, but criticizes him for producing sensually alluring yet technically defi- cient works that sought to escape rather than authentically express the crisis of the modernist human condition. This article takes Adorno's essay as a starting point for a reexamination of Schreker's Der ferne Klang (1912) and defends the critical quality of Schreker's artistic conception. Adorno focuses on Schreker's idea of musical sound: Klang as a harmonic-timbral entity that draws attention to itself as sensuous sonority, evocative of pleasurable fantasy. However, the opera's text, which Schreker wrote himself, demonstrates a critical awareness of the problems confronting the modern artist, whose expressive needs collide with society's limitations. While the musical dimension evokes the ineffable qualities of the artist's vision of expressive freedom, the realm of narrative embodies, in sometimes strikingly realistic terms, the all-too-present social realities he cannot escape. Rehearing Der ferne Klang after a close reading of the narrative reveals a dialectical dimension between music and text that problematizes Adorno's critique.
Modeling Haplotype Block Variation Using Markov Chains
Authors: Greenspan G , Geiger D 
Published: December 2005

Abstract
Models of background variation in genomic regions form the basis of linkage disequilibrium mapping methods. In this work we analyze a background model that groups SNPs into haplotype blocks and represents the dependencies between blocks by a Markov chain. We develop an error measure to compare the performance of this model against the common model that assumes that blocks are independent. By examining data from the International Haplotype Mapping project, we show how the Markov model over haplotype blocks is most accurate when representing blocks in strong linkage disequilibrium. This contrasts with the independent model, which is rendered less accurate by linkage disequilibrium. We provide a theoretical explanation for this surprising property of the Markov model and relate its behavior to allele diversity.
Optimal Design and Analysis of Genetic Studies on Gene Expression
Authors: Fu Jingyuan , Jansen Ritsert C 
Published: December 2005

Abstract
Whole-genome profiling of gene expression in a segregating population has the potential to identify the regulatory consequences of natural allelic variation. Costs of such studies are high and require that resources—microarrays and population—are used as efficiently as possible. We show that current studies can be improved significantly by a new design for two-color microarrays. Our “distant pair design” profiles twice as many individuals as there are arrays, cohybridizes individuals with dissimilar genomes, gives more weight to known regulatory loci if wished, and therewith maximizes the power for decomposing expression variation into regulatory factors. It can also exploit a large population (larger than twice the number of available microarrays) as a useful resource to select the most dissimilar pairs of individuals from. Our approach identifies more regulatory factors than alternative strategies do in computer simulations for realistic genome sizes, and similar promising results are obtained in an application on Arabidopsis thaliana. Our results will aid the design and analysis of future studies on gene expression and will help to shed more light on gene regulatory networks.
Efficient Inference of Haplotypes From Genotypes on a Large Animal Pedigree
Authors: Baruch Eyal , Weller Joel Ira , Cohen-Zinder Miri , Ron Micha , Seroussi Eyal 
Published: December 2005

Abstract
We present a simple algorithm for reconstruction of haplotypes from a sample of multilocus genotypes. The algorithm is aimed specifically for analysis of very large pedigrees for small chromosomal segments, where recombination frequency within the chromosomal segment can be assumed to be zero. The algorithm was tested both on simulated pedigrees of 155 individuals in a family structure of three generations and on real data of 1149 animals from the Israeli Holstein dairy cattle population, including 406 bulls with genotypes, but no females with genotypes. The rate of haplotype resolution for the simulated data was &gt;91% with a standard deviation of 2%. With 20% missing data, the rate of haplotype resolution was 67.5% with a standard deviation of 1.3%. In both cases all recovered haplotypes were correct. In the real data, allele origin was resolved for 22% of the heterozygous genotypes, even though 70% of the genotypes were missing. Haplotypes were resolved for 36% of the males. Computing time was insignificant for both data sets. Despite the intricacy of large-scale real pedigree genotypes, the proposed algorithm provides a practical rule-based solution for resolving haplotypes for small chromosomal segments in commercial animal populations.
Evolutionary Rates and Expression Level in Chlamydomonas
Authors: Popescu Cristina E , Borza Tudor , Bielawski Joseph P , Lee Robert W 
Published: December 2005

Abstract
In many biological systems, especially bacteria and unicellular eukaryotes, rates of synonymous and nonsynonymous nucleotide divergence are negatively correlated with the level of gene expression, a phenomenon that has been attributed to natural selection. Surprisingly, this relationship has not been examined in many important groups, including the unicellular model organism Chlamydomonas reinhardtii. Prior to this study, comparative data on protein-coding sequences from C. reinhardtii and its close noninterfertile relative C. incerta were very limited. We compiled and analyzed protein-coding sequences for 67 nuclear genes from these taxa; the sequences were mostly obtained from the C. reinhardtii EST database and our C. incerta EST data. Compositional and synonymous codon usage biases varied among genes within each species but were highly correlated between the orthologous genes of the two species. Relative rates of synonymous and nonsynonymous substitution across genes varied widely and showed a strong negative correlation with the level of gene expression estimated by the codon adaptation index. Our comparative analysis of substitution rates in introns of lowly and highly expressed genes suggests that natural selection has a larger contribution than mutation to the observed correlation between evolutionary rates and gene expression level in Chlamydomonas.
Clinal Variation in phyB2, a Candidate Gene for Day-Length-Induced Growth Cessation and Bud Set, Across a Latitudinal Gradient in European Aspen (Populus tremula)
Authors: Ingvarsson Pär K , García M Victoria , Hall David , Luquez Virginia , Jansson Stefan 
Published: December 2005

Abstract
The initiation of growth cessation and dormancy represents a critical ecological and evolutionary trade-off between survival and growth in most forest trees. The most important environmental cue regulating the initiation of dormancy is a shortening of the photoperiod and phytochrome genes have been implicated in short-day-induced bud set and growth cessation in Populus. We characterized patterns of DNA sequence variation at the putative candidate gene phyB2 in 4 populations of European aspen (Populus tremula) and scored single-nucleotide polymorphisms in an additional 12 populations collected along a latitudinal gradient in Sweden. We also measured bud set from a subset of these trees in a growth chamber experiment. Buds set showed significant clinal variation with latitude, explaining ∼90% of the population variation in bud set. A sliding-window scan of phyB2 identified six putative regions with enhanced population differentiation and four SNPs showed significant clinal variation. The clinal variation at individual SNPs is suggestive of an adaptive response in phyB2 to local photoperiodic conditions. Three of four SNPs showing clinal variation were located in regions with excessive genetic differentiation, demonstrating that searching for regions of high genetic differentiation can be useful for identifying sites putatively involved in local adaptation.
Allele Frequency Distribution Under Recurrent Selective Sweeps
Authors: Kim Yuseob 
Published: December 2005

Abstract
The allele frequency of a neutral variant in a population is pushed either upward or downward by directional selection on a linked beneficial mutation (“selective sweeps”). DNA sequences sampled after the fixation of the beneficial allele thus contain an excess of rare neutral alleles. This study investigates the allele frequency distribution under selective sweep models using analytic approximation and simulation. First, given a single selective sweep at a fixed time, I derive an expression for the sampling probabilities of neutral mutants. This solution can be used to estimate the time of the fixation of a beneficial allele from sequence data. Next, I obtain an approximation to mean allele frequencies under recurrent selective sweeps. Under recurrent sweeps, the frequency spectrum is skewed toward rare alleles. However, the excess of high-frequency derived alleles, previously shown to be a signature of single selective sweeps, disappears with recurrent sweeps. It is shown that, using this approximation and multilocus polymorphism data, genomewide parameters of directional selection can be estimated.
The Concordance of Gene Trees and Species Trees at Two Linked Loci
Authors: Slatkin Montgomery , Pollack Joshua L 
Published: December 2005

Abstract
The gene genealogies of two linked loci in three species are analyzed using a series of Markov chain models. We calculate the probability that the gene tree of one locus is concordant with the species tree, given that the gene tree of the other locus is concordant. We define a threshold value of the recombination rate, r*, to be the rate for which the difference between the conditional probability of concordance and its asymptotic value is reduced to 5% of the initial difference. We find that, although r* depends in a complicated way on the times of speciation and effective population sizes, it is always relatively small, &lt;10/N4, where N4 is the effective size of the species represented by the internal branch of the species tree. Consequently, the concordance of gene trees of neutral loci with the species tree is expected to be on roughly the same length scale on the chromosome as the extent of significant linkage disequilibrium within species unless the effective size of contemporary populations is very different from the effective sizes of their ancestral populations. Both balancing selection and selective sweeps can result in much longer genomic regions having concordant gene trees.
Variable Pleiotropic Effects From Mutations at the Same Locus Hamper Prediction of Fitness From a Fitness Component
Authors: Pepin Kim M , Samuel Melanie A , Wichman Holly A 
Published: December 2005

Abstract
The relationship of genotype, fitness components, and fitness can be complicated by genetic effects such as pleiotropy and epistasis and by heterogeneous environments. However, because it is often difficult to measure genotype and fitness directly, fitness components are commonly used to estimate fitness without regard to genetic architecture. The small bacteriophage ϕX174 enables direct evaluation of genetic and environmental effects on fitness components and fitness. We used 15 mutants to study mutation effects on attachment rate and fitness in six hosts. The mutants differed from our lab strain of ϕX174 by only one or two amino acids in the major capsid protein (gpF, sites 101 and 102). The sites are variable in natural and experimentally evolved ϕX174 populations and affect phage attachment rate. Within the limits of detection of our assays, all mutations were neutral or deleterious relative to the wild type; 11 mutants had decreased host range. While fitness was predictable from attachment rate in most cases, 3 mutants had rapid attachment but low fitness on most hosts. Thus, some mutations had a pleiotropic effect on a fitness component other than attachment rate. In addition, on one host most mutants had high attachment rate but decreased fitness, suggesting that pleiotropic effects also depended on host. The data highlight that even in this simple, well-characterized system, prediction of fitness from a fitness component depends on genetic architecture and environment.