bluuebunny/crossref_metadata_2025_split huggingface dataset:
Postural and lateral asymmetries in the ontogeny of handedness during infancy
Authors: Michel George F. , Harkins Debra A. 
Published: January 2005

AbstractTen newborn infants who preferred to lie with their heads turned rightward and ten who preferred to lie with their heads turned leftward had their hand‐use preferences for reaching assessed at 8 different ages during the period 12–74 weeks postpartum. Eighteen infants maintained stable hand‐use preferences throughout this period and the direction of their neonatal head orientation preference predicted the hand they preferred to use. The neonatal head‐turn preference was maintained through the first 2 months and induced lateral asymmetries in visual regard and motor control of the hands. These lateral asymmetries are plausible contributors to mechanisms linking neonatal headturn preference to infant hand‐use preference. Thus, the dextral bias in handedness may be derived, in part, from the rightward bias in neonatal head‐turn preference.
Play profiles of captive adult orangutans: A developmental perspective
Authors: Zucker Evan L. , Dennon M. Beth , Puleo Stephanie G. , Maple Terry L. 
Published: January 2005

AbstractThe social play of 6 adult orangutan heterosexual dyads was observed, and the frequencies of the component behaviors extracted. Frequencies were converted to proportions of total play outputs for each individual and for each age/sex class, and then compared to the proportions observed for the social play of juvenile and adolescent orangutans. Adult play was more stationary, and contact maintaining, in style than was the play of younger orangutans. For the females, rolling and grabbing comprised similar proportions of the play repertoires, whereas for males, slapping and biting were developmentally consistent. For adult males, little chasing was observed, although this behavior was prominant in the play of immature males. These developmental changes in orangutan social play are addressed with respect to the natural history and ecology of orangutans, the refinement of communication skills, and the influences of captivity on social play.
Long‐term effects of prenatal stress on HPA axis activity in juvenile rhesus monkeys
Authors: Clarke A. S. , Wittwer D. J. , Abbott D. H. , Schneider M. L. 
Published: January 2005

AbstractThe effect of stress to the pregnant mother on hormonal responses of the offspring to stressful events was investigated in juvenile rhesus monkeys. Six pregnant monkeys were repeatedly removed from their home cages and exposed to unpredictable noise during mid‐ to late gestation (Days 90–145 postconception), while six undisturbed pregnant mothers served as controls. Blood samples were collected from the juvenile offspring under anesthesia on four occasions and assayed for ACTH and cortisol. In a second experiment, blood samples were collected from the awake offspring under a baseline and four progressively stressful conditions. Offspring of stressed mothers showed higher ACTH and cortisol levels than control offspring at all four anesthesia samples and at a nonanesthesized home cage baseline. Prenatally stressed offspring also showed higher ACTH values in all four stress conditions. Cortisol values were similar for the two groups under the stress conditions. The disparity between the two groups in the relationship between ACTH and cortisol was greatest in the most stressful condition, suggesting regulatory differences between the two groups. These results indicate that offspring of primate mothers stressed during pregnancy show enhanced HPA axis responsivity to stressors later in life, and concur with rodent findings indicating that prenatal stress may have long‐term effects on HPA axis regulation. © 1994 John Wiley & Sons, Inc.
Tonic immobility and high‐intensity calls in a precocial chick as a function of age, diet, and time of day
Authors: Hill Wendy L. , Fleming Tara M. , Shrier Eric M. 
Published: January 2005

AbstractTonic immobility (TI) and high‐intensity vocalizations are two antipredator behaviors employed by domestic chicks (Gallus gallus) which vary in their function and the proximate mechanisms that govern them. In the present study, we sought to determine the influence of age (3 or 10 days old), diet (control or tryptophan‐free), and time of testing (A.M. or P.M.) on the duration of TI and the number of calls produced in domestic chicks. Older chicks remained immobile significantly longer than younger chicks as did subjects on the control diet or those tested at night. However, 3‐day‐old chicks had significantly shorter TI durations only when tested in the A.M.: TI did not differ between age groups when subjects were tested in the P.M. Three‐day‐olds called significantly more than 10‐day‐olds when given the control diet and when tested in the P.M. but vocalization frequencies did not differ between age groups during the A.M. testing or when given the tryptophan‐free diet (T‐). Vocalization rate (calls/TI duration), however, was significantly greater during the A.M. testing. These results emphasize the importance of considering circadian rhythms and behavioral development. Furthermore, an integrative view of the proximate mechanisms and adaptive functions of TI and high‐intensity vocalizations is presented.©1994 John Wiley & Sons, Inc.
Effects of physiological state on oral habituation in developing rats: Cellular and extracellular dehydration
Authors: Swithers Susan E. 
Published: January 2005

AbstractHydrational state has been demonstrated to influence intake of various solutions in young rat pups. For instance, both cellular and extracellular dehydration produce an enhancement of intake in pups tested at 6 days of age. However, the behavioral mechanisms that result in increased intake following manipulations of hydrational state have been less extensively studied. The impact of hydrational state on behavioral responsiveness in young rat pups was examined by assessing the pattern of responding to a series of repeated oral infusions of diet. Pups were tested at 6, 12, or 18 days of age following either acute cellular dehydration produced by injection of 1 M NaCl or acute extracellular dehydration produced by injection of 10% polyethylene glycol (PEG). Oral responsiveness to a series of 30 brief infusions of one of four taste solutions (water, 10% sucrose, 0.135 M NaCl, or 1 M NaCl) was measured. Each infusion lasted 3 s and there was 1 min between infusions. The pattern of oral responding to solutions was affected by the developmental age of the pup, the hydrational state of the pup, and the solution offered, with the largest effects of dehydration observed in the youngest animals. In all conditions except one, pups habituated to repeated infusions. The exception was the failure of extracellularly dehydrated 6‐day‐old pups to display habituation to oral infusions of sucrose. These results suggest that, although intake is enhanced by both cellular and extracellular dehydration in very young pups, the behavioral changes responsible for the enhancement of intake after cellular dehydration are different from the behavioral changes resulting from extracellular dehydration. This dissociation of behavioral effects of dehydration in young pups demonstrates that intake measures alone may obscure subtle differences in behavior and argues for the utility of dissection of behavioral components in understanding the neural and physiological control of behavior. © 1995 John Wiley & Sons, Inc.
Total cortisol, free cortisol, and growth hormone associated with brief social separation experiences in young macaques
Authors: Laudenslager Mark L. , Boccia Maria L. , Berger Christy L. , Gennaro‐Ruggles Mary M. , McFerran Britta , Reite Martin L. 
Published: January 2005

AbstractMany behavioral, immunological, and physiological consequences of brief maternal separation in bonnet (Macaca radiata) and pigtail monkeys (Macaca nemistrina) have been documented. However, the impact of social separation on plasma cortisol and growth hormone is unknown for these particular species. In the present study, the behavioral and endocrinological consequences of a 2‐week maternal separation in socially housed infant bonnet and pigtail monkeys were followed. In seven pairs (separated and matched control) of bonnet and six pairs of pigtail infants, plasma was obtained under baseline, separated, and reunion conditions twice weekly for the duration of the study. Blood samples were obtained from both infants of the pair in approximately 10 min. Plasma total cortisol, free cortisol, and growth hormone were measured in these samples. Focal animal behavioral observations were made on all subjects twice daily throughout the study period. In both species, total cortisol and free cortisol rose immediately following maternal separation in comparison to the matched nonseparated controls and returned to basal levels (e.g., that of matched non‐separted controls) following reunion with the mother. In contrast, plasma growth hormone rose only in the pigtail infants over a time course that peaked around the time of reunion. Multiple regression techniques indicated for the first week of separation, in the separated but not control subjects, that mean plasma free and total cortisol was positively related to distress behaviors (vocalization and postural slouch) observed during this week and negatively related to social behaviors (play and proximity to others) noted during the same period. In contrast, plasma growth hormone was related to both species and sex of the subjects but unrelated to behavioral variables. © 1995 John Wiley & Sons, Inc.
Testosterone‐induced shortening of the storage phase of song development in birds interferes with vocal learning
Authors: Whaling C. S. , Nelson D. A. , Marler P. 
Published: January 2005

AbstractBird song is a complex, learned behavior. Vocal learning in sparrows involves several different processes that occur in a distinct temporal pattern over the course of the first year of life. Songs are acquired without practice during a sensitive period within the first 3 months of life and rehearsal of the acquired song does not begin until 7 or 8 months of age. The function of the storage period between song acquisition and production is not known. We set out to investigate its significance by administering testosterone, known to stimulate production of adult song, to birds at 100 days of age after song acquisition was completed but some 5 months prior to normal song onset. Most testosterone‐treated birds produced abnormal songs resembling those of males raised in acoustic isolation suggesting that, in sparrows, events occurring during the storage phase play a significant role in vocal learning. © 1995 John Wiley & Sons, Inc.
Molecular mechanics of organic halides. III. Fluorinated olefins
Authors: Meyer A. Y. 
Published: January 2005

AbstractA molecular mechanical force field for fluorinated ethylenes and propylenes is described. The field computes geometries, dipole moments, and energy differences between isomers and rotamers. Component analysis indicates that “classical” strains alone (skeletal, nonbonded, electrostatic) cannot account for energy relationships. The discussion is supplemented by a semiempirical quantum chemical comparison of cis‐ and trans‐FCHCHF and of gauche‐ and anti‐FCH2CH2F.
An ab initio study of the geometry, harmonic and anharmonic force fields, and fundamental vibrational frequencies of cis‐ and trans‐ thiolformic acid
Authors: Bock Charles W. , Trachtman Mendel , George Philip 
Published: January 2005

AbstractThe geometry, harmonic and anharmonic force fields, and fundamental vibrational frequencies of cis‐ and trans‐thiolformic acid are studied ab initio in the 4‐31G basis set. An extensive comparison is made between changes in diagonal and off‐diagonal quadratic and cubic force constants and diagonal stretching quartic constants in going from the chain to the ring structure in thiolformic acid and formic acid. The changes in the force constants are indicative of a much weaker interaction in the trans conformer between SH and OC, compared with O–H and OC, in keeping with the weaker hydrogenbonding property of the SH group in general.
The torsional potential function for n‐butane
Authors: Allinger N. L. , Profeta S. 
Published: January 2005

AbstractThe energies of four different conformations for n‐butane were calculated by the ab initio method using an STO‐3G basis set. Fully relaxed molecular geometries obtained from molecular mechanics (MM2) were used. The two energy minima [anti (C2h), gauche (C2)] and the two maxima (C2, C2v) had the following relative energies: 0.0, 0.88, 3.56, 5.99 kcal/mole. These are approximate Hartree–Fock numbers. It is estimated that inclusion of electron correlation in the calculation would lower the last number to about 5.1 kcal/mole while leaving the first three values essentially unchanged.
The barrier to internal rotation in Ge2H6
Authors: Hinchliffe Alan 
Published: January 2005

AbstractHigh‐quality SCF‐MO calculations yield a barrier to internal rotation of 1.70 kJ mole−1 for Ge2H6. A new contraction scheme is reported for Dunning's larger Ge basis set. Geometry optimization, although carried out, is unimportant in this particular calculation. Wavefunctions and properties are reported for GeH4 and the staggered and eclipsed conformers of Ge2H6. The magnitude of the calculated barrier is more physically reasonable than those deduced from experimental data. Comparisons are made across the two series X2H6 and CH3XH3.
The computational application of the Cahn–Ingold–Prelog rules 1 and 2
Authors: Meyer Edgar F. 
Published: January 2005

AbstractCahn–Ingold–Prelog (CIP) rules 1 and 2 (material differences) have been expressed in the formal logic of a high‐level computer language (FORTRAN IV) on a laboratory minicomputer (PDP 11/40) by the program CHIRAL. An oversight in the CIP formalism in the treatment of rings was treated on an ad hoc basis; the problem has been expressed simply in terms of elementary graph theory in a way consistent with and similar to chemical notation. An example of the operation of CHIRAL is provided and the internal procedures discussed.
A method for constrained energy minimization of macromolecules
Authors: Van Gunsteren W. F. , Karplus M. 
Published: January 2005

AbstractTwo algorithms for the local energy minimization of the structure of macromolecules in the presence of constraints are proposed. They are a combination of the method of steepest descents and the method of conjugate gradients with the procedure SHAKE, by which distance constraints can be satisfied. The two algorithms are tested by applying them to a small protein, the bovine pancreatic trypsin inhibitor (BPTI), and compared with the penalty function method for conserving constraints. The efficiency of the proposed methods depends on the level of interdependence of the constraints. For bond‐length constraints, the use of SHAKE is superior to the penalty function method. However, when bond‐angle constraints are included, SHAKE is more efficient only if the curvature of the penalty function is considerably greater than that of the potential function being minimized. The results indicate that with bond‐length constraints the minimization behavior is similar to that without constraints. However, the simultaneous application of bond‐length and bond‐angle constraints appears to confine the molecule to a very limited part of configuration space, very different from the part covered by an unconstrained minimization. This conclusion calls into question energy minimizations of protein systems in which only the dihedral angles are allowed to vary.
Systematic synthesis design. 8. Generation of reaction sequences
Authors: Hendrickson James B. , Braun‐Keller Elaine 
Published: January 2005

AbstractThe numerical description of functionality allows a rigorous generation of all reactions from one structure (or partial structure) to another. The minimum number of steps required can be calculated and this “reaction distance” used to guide computer generation of sequences to converge on the target structure. A computer algorithm is described for efficient generation of all shortest synthetic routes between two given molecules as starting material and product. The program is seen as a prototype of a complete synthesis design program.
Properties of strong hydrogen‐bonded systems. II. Ab initioSCF‐MO study of the hydrogen bond between nitric acid and ammonia
Authors: Latajka Z. , Szczçśniak M. M. , Ratajczak H. , Orville‐Thomas W. J. 
Published: January 2005

AbstractThe hydrogen‐bonded complex between nitric acid and ammonia molecules has been studied by the ab initio molecular orbital method using the 4‐31G basis set. The calculated interaction energy for the complex (ΔE = −91.4 kJ mole−1) indicates that one is dealing with the strongest “nonionic” H‐bonded complex considered hitherto by theoretical methods. Other properties of the hydrogen‐bonded complex such as geometrical parameters, dipole moment, amount of charge transfer, and stretching force constants of the OH and (OH)… N bonds are calculated and discussed.
Conformational stability and flexibility of the ala dipeptide in free space and water: Monte Carlo computer simulation studies
Authors: Ravishanker G. , Mezei M. , Beveridge D. L. 
Published: January 2005

AbstractMonte Carlo determinations of the intramolecular thermodynamics of the Ala dipeptide in the C7, C5, αR, and PII conformations are reported. The calculations are carried out in the quasiharmonic approximation, with intramolecular entropies determined from the covariance matrix of the atomic displacements. The free energy of transition from C7 to C5, αR, and PII are found to be endergonic and dominated by the intrinsic energy of disrupting the intramolecular hydrogen bond in the C7 conformation. These results are combined with previous estimates of the free energy of hydration of the Ala dipeptide in water computed from liquid state Monte Carlo simulations using the probability ratio method. The net free energy of C7, αR, and PII are found to be similar, and it is thus reasonable to expect that all three forms are thermally populated at ambient temperature. The intermolecular carbonyl‐water hydrogen bond in C5, αR, and PII competes successfully with the intramolecular NH…︁OC interaction in C7.
Energy‐optimized GTO basis sets for LCAO Calculations. A Gradient Approach
Authors: Faegri Knut , Almlof Jan 
Published: January 2005

AbstractThe use of gradient techniques for the development of energy‐optimized basis sets has been investigated. The region where the energy surface is approximately quadratic with a positive definite Hessian is found to be very small for large basis sets. However, scaled Newton‐Raphson methods prove quite effective even when the starting point is outside this region. The analytic calculation of the Hessian is found to be most efficient in terms of computing time.
MINDO/3 Study of the Rearrangement of 1‐Methylcyclohexyl Cation to 1,2‐Dimethylcyclopentyl Cation
Authors: Viruela‐Martín P. M. , Nebot‐Gil I. , Tomás F. , Viruela‐Martín R. 
Published: January 2005

AbstractThe rearrangement of the 1‐methylcyclohexyl cation to the 1,2‐dimethylcyclopentyl cation has been studied by MINDO/3 calculations, as an application of the branching mechanism model for cycloalkanes. Possible intermediates and transition states have been characterized by diagonalization of their Hessian matrixes. Two nonequivalent pathways, α and β scissions, are relatively close in energy. The calculated transition states are almost equivalent in energy to those found for cyclohexyl cation. Hence, the energy barriers are higher for the rearrangement of the 1‐methyl than for cyclohexyl cation, because the former is less stable than the latter.
Substituent Effects on the Low‐Lying Singlet and Triplet States of Methylene
Authors: Farrǵs Jaume , Olivella Santiago , Solé Albert , Vilarrasa Jaume 
Published: January 2005

AbstractThe relative energies of the three lower‐lying singlet states (here called Sa, Sb, and Sc for the sake of generality) and the lowest triplet state of CHX and CX2 carbenes (in which X = Li, BeH, BH2, NH2, OH, or F) are evaluated by means of the semiempirical MNDO method as well as, for some species, by means of ab initio calculations at the 6‐31G, MP3/6‐31G, and MP3/6‐31G* levels. Calculations for CH(CN) and C(CN)2 are also reported. In spite of the known MNDO overestimation of the stability of the σ1π1 configurations of methylene, this method turns out to be satisfactory for most carbenes reported here. Emphasis is put on the appearance of the plots of the ΔH values vs. the carbene bond angles for the different states and on the seldom considered Sb states (1B1 for C2v carbenes). A carbene classification is proposed on the basis of the form of these plots. For carbenes with π‐acceptor substituents such as those of “type IA”, open‐shell, diradical configurations are predicted for the lowest singlet states, so that no significant structural differences should be expected between their lowest singlet and triplet states. On the other hand, for carbenes with strong π‐donor substituents, either “type ID” or “IID”, the closed‐shell singlets appear to be the ground states, and the singlet and triplet behaviors should be much more clearly distinguishable.
Transfer‐Matrix Method for Subgraph Enumeration: Applications to Polypyrene Fusenes
Authors: Klein D. J. , Hite G. E. , Schmalz T. G. 
Published: January 2005

AbstractA frequently encountered problem in chemical applications is that of a weighted enumeration (or summation over) a class of extended subgraphs of a given system graph, which might represent a chemical structure. Some aspects of a powerful transfer‐matrix method are described for treating such graphtheoretic weighted enumeration problems. This method is seen to be particularly amenable for system graphs which are long in one direction and narrow in transverse directions. When the system graph is uniform (i.e., translationally symmetric) along one extended direction, asymptotic results can be readily extracted.A second point of emphasis here is that the weighted enumeration problems of the type studied here naturally arise in computing matrix elements over cluster expanded wave functions, though most applications so far framed in the literature differ from this. Size consistency and size‐extensivity aspects of this application are noted in terms of the transfer‐matrix approach.Polypyrene fusene strips of varying lengths are considered as applications of the transfer‐matrix methods for two weighted enumeration problems. Different graph‐theoretic problems are noted to arise for low‐order cluster expanded wave functions, such as in fact occur in both the Herndon‐Simpson and the Pauling‐Wheland resonance theories. For higher‐order wave function ansätze the graph‐theoretic problems would simply have more complicated weights and transfer matrices, which for the present examples are very small (i.e., 2 by 2 and 3 by 3).
Conformational Dynamics of 9,9‐Dimethyl‐1,5‐Dihetero‐Spiro [5.5] Undecanes by Molecular Mechanics Calculations: A Three‐Dimensional Topological Approach
Authors: Iratçabal P. , Liotard D. 
Published: January 2005

AbstractThe dynamic behavior of 9,9‐dimethyl‐1,5‐dihetero‐spiro [5.5] undecanes is investigated by molecular mechanics calculations. A topological approach is taken which leads to a model consistent with the available NMR data. A three‐dimensional representation of the conformational potential energy surface is given.