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Showing papers by "Max Planck Society published in 1997"


Journal ArticleDOI
TL;DR: In this article, the authors used high-resolution N-body simulations to study the equilibrium density profiles of dark matter halos in hierarchically clustering universes, and they found that all such profiles have the same shape, independent of the halo mass, the initial density fluctuation spectrum, and the values of the cosmological parameters.
Abstract: We use high-resolution N-body simulations to study the equilibrium density profiles of dark matter halos in hierarchically clustering universes. We find that all such profiles have the same shape, independent of the halo mass, the initial density fluctuation spectrum, and the values of the cosmological parameters. Spherically averaged equilibrium profiles are well fitted over two decades in radius by a simple formula originally proposed to describe the structure of galaxy clusters in a cold dark matter universe. In any particular cosmology, the two scale parameters of the fit, the halo mass and its characteristic density, are strongly correlated. Low-mass halos are significantly denser than more massive systems, a correlation that reflects the higher collapse redshift of small halos. The characteristic density of an equilibrium halo is proportional to the density of the universe at the time it was assembled. A suitable definition of this assembly time allows the same proportionality constant to be used for all the cosmologies that we have tested. We compare our results with previous work on halo density profiles and show that there is good agreement. We also provide a step-by-step analytic procedure, based on the Press-Schechter formalism, that allows accurate equilibrium profiles to be calculated as a function of mass in any hierarchical model.

9,729 citations


Journal ArticleDOI
Werner Risau1
17 Apr 1997-Nature
TL;DR: Understanding of the molecular basis underlying angiogenesis, particularly from the study of mice lacking some of the signalling systems involved, has greatly improved, and may suggest new approaches for treating conditions such as cancer that depend onAngiogenesis.
Abstract: After the developing embryo has formed a primary vascular plexus by a process termed vasculogenesis, further blood vessels are generated by both sprouting and non-sprouting angiogenesis, which are progressively pruned and remodelled into a functional adult circulatory system. Recent results, particularly from the study of mice lacking some of the signalling systems involved, have greatly improved our understanding of the molecular basis underlying these events, and may suggest new approaches for treating conditions such as cancer that depend on angiogenesis.

5,793 citations


Reference BookDOI
10 Jul 1997
TL;DR: This paper presents a meta-modelling system that automates the very labor-intensive and therefore time-heavy and therefore expensive and expensive process of characterization and activation of Solid Catalysts.
Abstract: Preparation of Solid Catalysts. Characterization of Solid Catalysts. Model Systems. Elementary Steps and Mechanisms. Kinetics and Transport Processes. Deactivation and Regeneration. Special Catalytic Systems. Laboratory Reactors. Reaction Engineering. Environmental Catalysis. Inorganic Reactions. Energy-related Catalysis. Organic Reactions.

4,227 citations


Book
01 Jan 1997
TL;DR: Using nonlinear methods when determinism is weak, as well as selected nonlinear phenomena, is suggested to be a viable alternative to linear methods.
Abstract: Part I. Basic Concepts: 1. Introduction: why nonlinear methods? 2. Linear tools and general considerations 3. Phase space methods 4. Determinism and predictability 5. Instability: Lyapunov exponents 6. Self-similarity: dimensions 7. Using nonlinear methods when determinism is weak 8. Selected nonlinear phenomena Part II. Advanced Topics: 9. Advanced embedding methods 10. Chaotic data and noise 11. More about invariant quantities 12. Modeling and forecasting 13. Chaos control 14. Other selected topics Appendix 1. Efficient neighbour searching Appendix 2. Program listings Appendix 3. Description of the experimental data sets.

4,019 citations


Journal ArticleDOI
10 Jan 1997-Science
TL;DR: In dual whole-cell voltage recordings from pyramidal neurons, the coincidence of post Synaptic action potentials and unitary excitatory postsynaptic potentials was found to induce changes in EPSPs.
Abstract: Activity-driven modifications in synaptic connections between neurons in the neocortex may occur during development and learning In dual whole-cell voltage recordings from pyramidal neurons, the coincidence of postsynaptic action potentials (APs) and unitary excitatory postsynaptic potentials (EPSPs) was found to induce changes in EPSPs Their average amplitudes were differentially up- or down-regulated, depending on the precise timing of postsynaptic APs relative to EPSPs These observations suggest that APs propagating back into dendrites serve to modify single active synaptic connections, depending on the pattern of electrical activity in the pre- and postsynaptic neurons

3,591 citations


Journal ArticleDOI
TL;DR: The data suggest that amoA represents a very powerful molecular tool for analyzing indigenous ammonia-oxidizing communities due to (i) its specificity, (ii) its fine-scale resolution of closely related populations, and (iii) the fact that a functional trait rather than a phylogenetic trait is detected.
Abstract: The naturally occurring genetic heterogeneity of autotrophic ammonia-oxidizing populations belonging to the beta subclass of the Proteobacteria was studied by using a newly developed PCR-based assay targeting a partial stretch of the gene which encodes the active-site polypeptide of ammonia monooxygenase (amoA). The PCR yielded a specific 491-bp fragment with all of the nitrifiers tested, but not with the homologous stretch of the particulate methane monooxygenase, a key enzyme of methane-oxidizing bacteria. The assay also specifically detected amoA in DNA extracted from various aquatic and terrestrial environments. The resulting PCR products retrieved from rice roots, activated sludge, a freshwater sample, and an enrichment culture were used for the generation of amoA gene libraries. No false positives were detected in a set of 47 randomly selected clone sequences that were analyzed further. The majority of the environmental sequences retrieved from rice roots and activated sludge grouped within the phylogenetic radiation defined by cultured strains of the genera Nitrosomonas and Nitrosospira. The comparative analysis identified members of both of these genera in activated sludge; however, only Nitrosospira-like sequences with very similar amino acid patterns were found on rice roots. Further differentiation of these molecular isolates was clearly possible on the nucleic acid level due to the accumulation of synonymous mutations, suggesting that several closely related but distinct Nitrosospira-like populations are the main colonizers of the rhizosphere of rice. Each of the amoA gene libraries obtained from the freshwater sample and the enrichment culture was dominated by a novel lineage that shared a branch with the Nitrosospira cluster but could not be assigned to any of the known pure cultures. Our data suggest that amoA represents a very powerful molecular tool for analyzing indigenous ammonia-oxidizing communities due to (i) its specificity, (ii) its fine-scale resolution of closely related populations, and (iii) the fact that a functional trait rather than a phylogenetic trait is detected.

2,576 citations


Journal ArticleDOI
TL;DR: It is shown that ubiquitination of β‐catenin is greatly reduced in Wnt‐expressing cells, providing the first evidence that the ubiquitin–proteasome degradation pathway may act downstream of GSK3β in the regulation ofβ‐ catenin.
Abstract: beta-catenin is a central component of the cadherin cell adhesion complex and plays an essential role in the Wingless/Wnt signaling pathway. In the current model of this pathway, the amount of beta-catenin (or its invertebrate homolog Armadillo) is tightly regulated and its steady-state level outside the cadherin-catenin complex is low in the absence of Wingless/Wnt signal. Here we show that the ubiquitin-dependent proteolysis system is involved in the regulation of beta-catenin turnover. beta-catenin, but not E-cadherin, p120(cas) or alpha-catenin, becomes stabilized when proteasome-mediated proteolysis is inhibited and this leads to the accumulation of multi-ubiquitinated forms of beta-catenin. Mutagenesis experiments demonstrate that substitution of the serine residues in the glycogen synthase kinase 3beta (GSK3beta) phosphorylation consensus motif of beta-catenin inhibits ubiquitination and results in stabilization of the protein. This motif in beta-catenin resembles a motif in IkappaB (inhibitor of NFkappaB) which is required for the phosphorylation-dependent degradation of IkappaB via the ubiquitin-proteasome pathway. We show that ubiquitination of beta-catenin is greatly reduced in Wnt-expressing cells, providing the first evidence that the ubiquitin-proteasome degradation pathway may act downstream of GSK3beta in the regulation of beta-catenin.

2,432 citations


Journal ArticleDOI
16 Jan 1997-Nature
TL;DR: Basaltic volcanism'samples' the Earth's mantle to great depths, because solid-state convection transports deep material into the (shallow) melting region as mentioned in this paper.
Abstract: Basaltic volcanism 'samples' the Earth's mantle to great depths, because solid-state convection transports deep material into the (shallow) melting region. The isotopic and trace-element chemistry of these basalts shows that the mantle contains several isotopically and chemically distinct components, which reflect its global evolution. This evolution is characterized by upper-mantle depletion of many trace elements, possible replenishment from the deeper, less depleted mantle, and the recycling of oceanic crust and lithosphere, but of only small amounts of continental material.

2,397 citations


Book
01 Jan 1997
TL;DR: This comprehensive evaluation and synthesis of a rapidly-developing field provides state-of-the-discipline reviews, and highlights areas of research which might be productive, should appeal to a wide variety of theoretical and applied researchers.
Abstract: Plants face a daunting array of creatures which eat them, bore into them and use virtually every plant part for food or shelter. However, plants are far from defenceless under attack. Although they cannot flee their attackers, they can produce defences, such as thorns, and can actively alter their chemistry and physiology in response to damage. For instance, young potato leaves being eaten by potato beetles respond by producing chemicals which inhibit beetle digestive enzymes. Research on these induced responses to herbivory has proceeded since the 1980s, and this comprehensive evaluation and synthesis of a rapidly-developing field provides state-of-the-discipline reviews, and highlights areas of research which might be productive. This overview should appeal to a wide variety of theoretical and applied researchers in ecology, evolutionary biology, plant biology, entomology and agriculture.

2,385 citations


Journal ArticleDOI
03 Apr 1997-Nature
TL;DR: Two β-type subunits are processed to an intermediate form, indicating that an additional nonspecific endopeptidase activity may exist which is important for peptide hydrolysis and for the generation of ligands for class I molecules of the major histocompatibility complex.
Abstract: The crystal structure of the 20S proteasome from the yeast Saccharomyces cerevisiae shows that its 28 protein subunits are arranged as an (α1...α7, β1...β7)2 complex in four stacked rings and occupy unique locations. The interior of the particle, which harbours the active sites, is only accessible by some very narrow side entrances. The β-type subunits are synthesized as proproteins before being proteolytically processed for assembly into the particle. The proforms of three of the seven different β-type subunits, (β1/PRE3, β2/PUP1 and β5/PRE2, are cleaved between the threonine at position 1 and the last glycine of the pro-sequence, with release of the active-site residue Thr 1. These three β-type subunits have inhibitor-binding sites, indicating that PRE2 has a chymotrypsin-like and a trypsin-like activity and that PRE3 has peptidylglutamyl peptide hydrolytic specificity. Other β-type subunits are processed to an intermediate form, indicating that an additional nonspecific endopeptidase activity may exist which is important for peptide hydrolysis and for the generation of ligands for class I molecules of the major histocompatibility complex.

2,235 citations


Book ChapterDOI
08 Oct 1997
TL;DR: A new method for performing a nonlinear form of Principal Component Analysis by the use of integral operator kernel functions is proposed and experimental results on polynomial feature extraction for pattern recognition are presented.
Abstract: A new method for performing a nonlinear form of Principal Component Analysis is proposed. By the use of integral operator kernel functions, one can efficiently compute principal components in highdimensional feature spaces, related to input space by some nonlinear map; for instance the space of all possible d-pixel products in images. We give the derivation of the method and present experimental results on polynomial feature extraction for pattern recognition.

Journal ArticleDOI
08 Aug 1997-Cell
TL;DR: In this paper, the authors observed that mice transgenic for exon 1 of the human HD gene carrying (CAG)115 to 157 repeat expansions develop pronounced neuronal intranuclear inclusions, containing the proteins huntingtin and ubiquitin, prior to developing a neurological phenotype.

Book
18 Sep 1997
TL;DR: In the face of complexity, policy research in the Face of Complexity as mentioned in this paper has been studied in the context of actor-centered institutionalism and actor-constellations.
Abstract: * Introduction * Policy Research in the Face of Complexity * Actor-Centered Institutionalism * Actors * Actor Constellations * Unilateral Action in Anarchic Fields and Minimal Institutions * Negotiated Agreements * Decisions by Majority Vote * Hierarchical Direction * Varieties of the Negotiating State

Journal ArticleDOI
TL;DR: The results show that alcohol abuse and dependence are often associated with other lifetime NCS/DSM-III-R disorders and suggest that, at least in recent cohorts, the alcohol use disorders are usually temporally secondary.
Abstract: Objective: To study patterns of co-occurrence of lifetimeDSM-III-Ralcohol disorders in a household sample. Methods: Data came from the National Comorbidity Survey (NCS), a nationally representative household survey. Diagnoses were based on a modified version of the Composite International Diagnostic Interview. Results: Respondents with lifetimeNCS/DSM-III-Ralcohol abuse or dependence had a high probability of carrying at least 1 other lifetimeNCS/DSM-III-Rdiagnosis. Retrospective reports have suggested that most lifetime co-occurring alcohol disorders begin at a later age than at least 1 other NCS/DSM-III-Rdisorder. Earlier disorders are generally stronger predictors of alcohol dependence than alcohol abuse and stronger among women than men. Lifetime co-occurrence is positively, but weakly, associated with the persistence of alcohol abuse among men and of alcohol dependence among both men and women. Conclusions: Caution is needed in interpreting the results due to the fact that diagnoses were made by nonclinicians and results are based on retrospective reports of the age at onset. Within the context of these limitations, though, these results show that alcohol abuse and dependence are often associated with other lifetimeDSM-III-Rdisorders and suggest that, at least in recent cohorts, the alcohol use disorders are usually temporally secondary. Prospective data and data based on clinically confirmed diagnoses are needed to verify these findings.

Journal ArticleDOI
TL;DR: Molecular dynamics simulations were performed on a system consisting of a bilayer of 64 molecules of the lipid dipalmitoylphosphatidylcholine and 23 water molecules per lipid to reproduce the correct density and to give a proper estimate of the area per lipid.

Journal ArticleDOI
TL;DR: In this paper, a common coding approach for the understanding of functional relationships between perception and action is discussed, and evidence from two types of induction tasks is reviewed: sensorimotor synchronisation and spatial compatibility tasks.
Abstract: A new framework for the understanding of functional relationships between perception and action is discussed. According to this framework, perceived events and planned actions share a common representational domain (common-coding approach). Supporting evidence from two classes of experimental paradigms is presented: induction paradigms and interference paradigms. Induction paradigms study how certain stimuli induce certain actions by virtue of similarity. Evidence from two types of induction tasks is reviewed: sensorimotor synchronisation and spatial compatibility tasks. Interference paradigms study the mutual interference between the perception of ongoing events and the preparation and control of ongoing action. Again, evidence from two types of such tasks is reviewed, implying interference in either direction. It is concluded that the evidence available supports the common coding principle. A further general principle emerging from these studies is the action effect principle that is, the principle that...

Journal ArticleDOI
TL;DR: In this paper, a reversible hydrogen storage system based on catalyzed reactions is proposed, where the catalytic acceleration of the reactions in both directions is achieved by doping alkali metal aluminium hydrides with a few mol% of selected Ti compounds.

Journal ArticleDOI
16 May 1997-Science
TL;DR: In this article, two important aerosol species, sulfate and organic particles, have large natural biogenic sources that depend in a highly complex fashion on environmental and ecological parameters and therefore are prone to influence by global change.
Abstract: Atmospheric aerosols play important roles in climate and atmospheric chemistry: They scatter sunlight, provide condensation nuclei for cloud droplets, and participate in heterogeneous chemical reactions. Two important aerosol species, sulfate and organic particles, have large natural biogenic sources that depend in a highly complex fashion on environmental and ecological parameters and therefore are prone to influence by global change. Reactions in and on sea-salt aerosol particles may have a strong influence on oxidation processes in the marine boundary layer through the production of halogen radicals, and reactions on mineral aerosols may significantly affect the cycles of nitrogen, sulfur, and atmospheric oxidants.

Journal ArticleDOI
Udo Seifert1
TL;DR: In this article, the authors describe the systematic physical theory developed to understand the static and dynamic aspects of membrane and vesicle configurations, and the preferred shapes arise from a competition between curvature energy which derives from the bending elasticity of the membrane, geometrical constraints such as fixed surface area and fixed enclosed volume, and a signature of the bilayer aspect.
Abstract: Vesicles consisting of a bilayer membrane of amphiphilic lipid molecules are remarkably flexible surfaces that show an amazing variety of shapes of different symmetry and topology. Owing to the fluidity of the membrane, shape transitions such as budding can be induced by temperature changes or the action of optical tweezers. Thermally excited shape fluctuations are both strong and slow enough to be visible by video microscopy. Depending on the physical conditions, vesicles adhere to and unbind from each other or a substrate. This article describes the systematic physical theory developed to understand the static and dynamic aspects of membrane and vesicle configurations. The preferred shapes arise from a competition between curvature energy, which derives from the bending elasticity of the membrane, geometrical constraints such as fixed surface area and fixed enclosed volume, and a signature of the bilayer aspect. These shapes of lowest energy are arranged into phase diagrams, which separate regi...

Journal ArticleDOI
18 Jul 1997-Science
TL;DR: The structural arrangement in the active site is consistent with a mostly associative mechanism of phosphoryl transfer and provides an explanation for the activation of Ras by glycine-12 and glutamine-61 mutations.
Abstract: The three-dimensional structure of the complex between human H-Ras bound to guanosine diphosphate and the guanosine triphosphatase (GTPase)-activating domain of the human GTPase-activating protein p120GAP (GAP-334) in the presence of aluminum fluoride was solved at a resolution of 2.5 angstroms. The structure shows the partly hydrophilic and partly hydrophobic nature of the communication between the two molecules, which explains the sensitivity of the interaction toward both salts and lipids. An arginine side chain (arginine-789) of GAP-334 is supplied into the active site of Ras to neutralize developing charges in the transition state. The switch II region of Ras is stabilized by GAP-334, thus allowing glutamine-61 of Ras, mutation of which activates the oncogenic potential, to participate in catalysis. The structural arrangement in the active site is consistent with a mostly associative mechanism of phosphoryl transfer and provides an explanation for the activation of Ras by glycine-12 and glutamine-61 mutations. Glycine-12 in the transition state mimic is within van der Waals distance of both arginine-789 of GAP-334 and glutamine-61 of Ras, and even its mutation to alanine would disturb the arrangements of residues in the transition state.

Journal ArticleDOI
TL;DR: The electrophysiological properties of the prototype store-operated current ICRAC are focused on, the regulatory mechanisms that control it are discussed, and recent advances toward the identification of molecular mechanisms involved in this ubiquitous and important Ca2+ entry pathway are considered.
Abstract: Calcium influx in nonexcitable cells regulates such diverse processes as exocytosis, contraction, enzyme control, gene regulation, cell proliferation, and apoptosis. The dominant Ca2+ entry pathway in these cells is the store-operated one, in which Ca2+ entry is governed by the Ca2+ content of the agonist-sensitive intracellular Ca2+ stores. Only recently has a Ca2+ current been described that is activated by store depletion. The properties of this new current, called Ca2+ release-activated Ca2+ current (ICRAC), have been investigated in detail using the patch-clamp technique. Despite intense research, the nature of the signal that couples Ca2+ store content to the Ca2+ channels in the plasma membrane has remained elusive. Although ICRAC appears to be the most effective and widespread influx pathway, other store-operated currents have also been observed. Although the Ca2+ release-activated Ca2+ channel has not yet been cloned, evidence continues to accumulate that the Drosophila trp gene might encode a store-operated Ca2+ channel. In this review, we describe the historical development of the field of Ca2+ signaling and the discovery of store-operated Ca2+ currents. We focus on the electrophysiological properties of the prototype store-operated current ICRAC, discuss the regulatory mechanisms that control it, and finally consider recent advances toward the identification of molecular mechanisms involved in this ubiquitous and important Ca2+ entry pathway.

Journal ArticleDOI
TL;DR: Drawing on both evolutionary and ontogenetic perspectives, the basic biological-genetic and social-cultural architecture of human development is outlined, suggesting that the lifespan architecture becomes more and more incomplete with age.
Abstract: Drawing on both evolutionary and ontogenetic perspectives, the basic biological-genetic and social-cultural architecture of human development is outlined. Three principles are involved. First, evolutionary selection pressure predicts a negative age correlation, and, therefore, genome-based plasticity and biological potential decrease with age. Second, for growth aspects of human development to extend further into the life span, culture-based resources are required at ever-increasing levels. Third, because of age-related losses in biological plasticity, the efficiency of culture is reduced as life span development unfolds. Joint application of these principles suggests that the lifespan architecture becomes more and more incomplete with age. Degree of completeness can be defined as the ratio between gains and losses in functioning. Two examples illustrate the implications of the lifespan architecture proposed. The first is a general theory of development involving the orchestration of three component processes: selection, optimization, and compensation. The second considers the task of completing the life course in the sense of achieving a positive balance between gains and losses for all age levels. This goal is increasingly more difficult to attain as human development is extended into advanced old age.

Journal ArticleDOI
TL;DR: The results show that on the United States postal service database of handwritten digits, the SV machine achieves the highest recognition accuracy, followed by the hybrid system, and the SV approach is thus not only theoretically well-founded but also superior in a practical application.
Abstract: The support vector (SV) machine is a novel type of learning machine, based on statistical learning theory, which contains polynomial classifiers, neural networks, and radial basis function (RBF) networks as special cases. In the RBF case, the SV algorithm automatically determines centers, weights, and threshold that minimize an upper bound on the expected test error. The present study is devoted to an experimental comparison of these machines with a classical approach, where the centers are determined by X-means clustering, and the weights are computed using error backpropagation. We consider three machines, namely, a classical RBF machine, an SV machine with Gaussian kernel, and a hybrid system with the centers determined by the SV method and the weights trained by error backpropagation. Our results show that on the United States postal service database of handwritten digits, the SV machine achieves the highest recognition accuracy, followed by the hybrid system. The SV approach is thus not only theoretically well-founded but also superior in a practical application.

Journal ArticleDOI
TL;DR: The use of this specific PCR in combination with denaturing gradient gel electrophoresis to probe the diversity of oxygenic phototrophic microorganisms in cultures, lichens, and complex microbial communities is demonstrated.
Abstract: We developed and tested a set of oligonucleotide primers for the specific amplification of 16S rRNA gene segments from cyanobacteria and plastids by PCR. PCR products were recovered from all cultures of cyanobacteria and diatoms that were checked but not from other bacteria and archaea. Gene segments selectively retrieved from cyanobacteria and diatoms in unialgal but nonaxenic cultures and from cyanobionts in lichens could be directly sequenced. In the context of growing sequence databases, this procedure allows rapid and phylogenetically meaningful identification without pure cultures or molecular cloning. We demonstrate the use of this specific PCR in combination with denaturing gradient gel electrophoresis to probe the diversity of oxygenic phototrophic microorganisms in cultures, lichens, and complex microbial communities.

Journal ArticleDOI
08 Aug 1997-Cell
TL;DR: In this study, it is shown that the proteolytic cleavage of a GST-huntingtin fusion protein leads to the formation of insoluble high molecular weight protein aggregates only when the polyglutamine expansion is in the pathogenic range.

Book
01 Jul 1997
TL;DR: In this paper, the authors present a survey of the state-of-the-art methods to solve the problem of self-defence and self-preservation in the context of artificial intelligence.
Abstract: Contents 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13.

Journal ArticleDOI
TL;DR: Practical and theoretical issues are discussed for testing the comparability, or measurement equivalence, of psychological constructs and detecting possible sociocultural difference on the constructs in cross-cultural research designs.
Abstract: Practical and theoretical issues are discussed for testing (a) the comparability, or measurement equivalence, of psychological constructs and (b) detecting possible sociocultural difference on the constructs in cross-cultural research designs. Specifically, strong factorial invariance (Meredith, 1993) of each variable's loading and intercept (mean-level) parameters implies that constructs are fundamentally the same in each sociocultural group, and thus comparable. Under this condition, hypotheses about the nature of sociocultural differences and similarities can be confidently and meaningfully tested among the constructs' moments in each sociocultural sample. Some of the issues involved in making such tests are reviewed and explicated within the framework of multiple-group mean and covariance structures analyses.

Journal ArticleDOI
TL;DR: In this article, a nonequilibrium molecular dynamics method for calculating the thermal conductivity is presented, which reverses the usual cause and effect picture, where the effect, the heat flux, is imposed on the system and the cause, the temperature gradient, is obtained from the simulation.
Abstract: A nonequilibrium molecular dynamics method for calculating the thermal conductivity is presented. It reverses the usual cause and effect picture. The “effect,” the heat flux, is imposed on the system and the “cause,” the temperature gradient is obtained from the simulation. Besides being very simple to implement, the scheme offers several advantages such as compatibility with periodic boundary conditions, conservation of total energy and total linear momentum, and the sampling of a rapidly converging quantity (temperature gradient) rather than a slowly converging one (heat flux). The scheme is tested on the Lennard-Jones fluid.

Journal ArticleDOI
11 Jul 1997-Cell
TL;DR: In this article, DNA was extracted from a Neandertal-type specimen found in 1856 in western Germany and a hitherto unknown mt-DNA sequence was determined by sequencing clones from short overlapping PCR products.

Journal ArticleDOI
TL;DR: In this paper, the authors examined the relationship between measures of sensory functioning (visual and auditory acuity) and intelligence (14 cognitive tasks representing a 5-factor space of psychometric intelligence) and found that the average proportion of individual differences in intellectual functioning connected to sensory functioning increased from 11% in adulthood to 31% in old age (70-103 years).
Abstract: Six hundred eighty seven individuals ages 25-103 years were studied cross-sectionally to examine the relationship between measures of sensory functioning (visual and auditory acuity) and intelligence (14 cognitive tasks representing a 5-factor space of psychometric intelligence). As predicted, the average proportion of individual differences in intellectual functioning connected to sensory functioning increased from 11% in adulthood (25-69 years) to 31% in old age (70-103 years). However, the link between fluid intellectual abilities and sensory functioning, albeit of different size, displayed a similarly high connection to age in both age groups. Several explanations are discussed, including a "common cause" hypothesis. In this vein, we argue that the increase in the age-associated link between sensory and intellectual functioning may reflect brain aging and that the search for explanations of cognitive aging phenomena would benefit from attending to factors that are shared between the 2 domains.