Showing papers by "University of Bonn published in 2001"
TL;DR: Dynamical properties of brain electrical activity from different recording regions and from different physiological and pathological brain states are compared and strongest indications of nonlinear deterministic dynamics were found for seizure activity.
Abstract: We compare dynamical properties of brain electrical activity from different recording regions and from different physiological and pathological brain states Using the nonlinear prediction error and an estimate of an effective correlation dimension in combination with the method of iterative amplitude adjusted surrogate data, we analyze sets of electroencephalographic (EEG) time series: surface EEG recordings from healthy volunteers with eyes closed and eyes open, and intracranial EEG recordings from epilepsy patients during the seizure free interval from within and from outside the seizure generating area as well as intracranial EEG recordings of epileptic seizures As a preanalysis step an inclusion criterion of weak stationarity was applied Surface EEG recordings with eyes open were compatible with the surrogates' null hypothesis of a Gaussian linear stochastic process Strongest indications of nonlinear deterministic dynamics were found for seizure activity Results of the other sets were found to be inbetween these two extremes
2,387 citations
TL;DR: The theory takes into account that people evaluate the kindness of an action not only by its consequences but also by the intention underlying this action, and explains the relevant stylized facts of a wide range of experimental games.
Abstract: This paper presents a formal theory of reciprocity. Reciprocity means that people reward kind actions and punish unkind ones. The theory takes into account that people evaluate the kindness of an action not only by its consequences but also by the intention underlying this action. The theory explains the relevant stylized facts of a wide range of experimental games. Among them are the ultimatum game, the gift-exchange game, a reduced best-shot game, the dictator game, the prisoner's dilemma, and public goods games. Furthermore, the theory explains why the same consequences trigger different reciprocal responses in different environments Finally the theory explains why in bilaterial interactions outcomes tend to be "fair" whereas in competitive markets even extremely unfair distributions may arise.
2,207 citations
TL;DR: In vitro differentiation, enrichment, and transplantation of neural precursor cells from human ES cells are described, depicting humanES cells as a source of transplantable neural precursors for possible nervous system repair.
Abstract: The remarkable developmental potential and replicative capacity of human embryonic stem (ES) cells promise an almost unlimited supply of specific cell types for transplantation therapies. Here we describe the in vitro differentiation, enrichment, and transplantation of neural precursor cells from human ES cells. Upon aggregation to embryoid bodies, differentiating ES cells formed large numbers of neural tube-like structures in the presence of fibroblast growth factor 2 (FGF-2). Neural precursors within these formations were isolated by selective enzymatic digestion and further purified on the basis of differential adhesion. Following withdrawal of FGF-2, they differentiated into neurons, astrocytes, and oligodendrocytes. After transplantation into the neonatal mouse brain, human ES cell-derived neural precursors were incorporated into a variety of brain regions, where they differentiated into both neurons and astrocytes. No teratoma formation was observed in the transplant recipients. These results depict human ES cells as a source of transplantable neural precursors for possible nervous system repair.
1,982 citations
TL;DR: The GAIA astrometric mission has recently been approved as one of the next two ''cornerstones'' of ESA's science programme, with a launch datetarget of not later than mid-2012 as discussed by the authors.
Abstract: The GAIA astrometric mission has recently been approved as one of thenext two ``cornerstones'' of ESA's science programme, with a launch datetarget of not later than mid-2012. GAIA will provide positional andradial velocity measurements with the accuracies needed to produce astereoscopic and kinematic census of about one billion stars throughoutour Galaxy (and into the Local Group), amounting to about 1 percent ofthe Galactic stellar population. GAIA's main scientific goal is toclarify the origin and history of our Galaxy, from a quantitative censusof the stellar populations. It will advance questions such as when thestars in our Galaxy formed, when and how it was assembled, and itsdistribution of dark matter. The survey aims for completeness to V=20mag, with accuracies of about 10 mu as at 15 mag. Combined withastrophysical information for each star, provided by on-boardmulti-colour photometry and (limited) spectroscopy, these data will havethe precision necessary to quantify the early formation, and subsequentdynamical, chemical and star formation evolution of our Galaxy.Additional products include detection and orbital classification of tensof thousands of extra-Solar planetary systems, and a comprehensivesurvey of some 105-106 minor bodies in our SolarSystem, through galaxies in the nearby Universe, to some 500 000 distantquasars. It will provide a number of stringent new tests of generalrelativity and cosmology. The complete satellite system was evaluated aspart of a detailed technology study, including a detailed payloaddesign, corresponding accuracy assesments, and results from a prototypedata reduction development. (Less)
1,281 citations
TL;DR: It is shown that CHIP abolishes the steroid-binding activity and transactivation potential of the glucocorticoid receptor, a well-characterized Hsp90 substrate, even though it has little effect on its synthesis.
Abstract: To maintain quality control in cells, mechanisms distinguish among improperly folded peptides, mature and functional proteins, and proteins to be targeted for degradation. The molecular chaperones, including heat-shock protein Hsp90, have the ability to recognize misfolded proteins and assist in their conversion to a functional conformation. Disruption of Hsp90 heterocomplexes by the Hsp90 inhibitor geldanamycin leads to substrate degradation through the ubiquitin-proteasome pathway, implicating this system in protein triage decisions. We previously identified CHIP (carboxyl terminus of Hsc70-interacting protein) to be an interaction partner of Hsc70 (ref. 4). CHIP also interacts directly with a tetratricopeptide repeat acceptor site of Hsp90, incorporating into Hsp90 heterocomplexes and eliciting release of the regulatory cofactor p23. Here we show that CHIP abolishes the steroid-binding activity and transactivation potential of the glucocorticoid receptor, a well-characterized Hsp90 substrate, even though it has little effect on its synthesis. Instead, CHIP induces ubiquitylation of the glucocorticoid receptor and degradation through the proteasome. By remodelling Hsp90 heterocomplexes to favour substrate degradation, CHIP modulates protein triage decisions that regulate the balance between protein folding and degradation for chaperone substrates.
976 citations
TL;DR: Divergent neural activations in response to TOM and SELF suggest that these important differential mental capacities of human self-consciousness are implemented at least in part in distinct brain regions.
969 citations
TL;DR: It is shown that the RC-TDT is equivalent to a special case of the FBAT method, and it is generalised to dominant, recessive and multi-allelic marker codings.
Abstract: With possibly incomplete nuclear families, the family based association test (FBAT) method allows one to evaluate any test statistic that can be expressed as the sum of products (covariance) between an arbitrary function of an offspring's genotype with an arbitrary function of the offspring's phenotype. We derive expressions needed to calculate the mean and variance of these test statistics under the null hypothesis of no linkage. To give some guidance on using the FBAT method, we present three simple data analysis strategies for different phenotypes: dichotomous (affection status), quantitative and censored (eg, the age of onset). We illustrate the approach by applying it to candidate gene data of the NIMH Alzheimer Disease Initiative. We show that the RC-TDT is equivalent to a special case of the FBAT method. This result allows us to generalise the RC-TDT to dominant, recessive and multi-allelic marker codings. Simulations compare the resulting FBAT tests to the RC-TDT and the S-TDT. The FBAT software is freely available.
764 citations
TL;DR: A growing body of research shows that this relative age effect in sport is a worldwide phenomenon and that it exists in many, but not all, competitive sports as discussed by the authors, and both physical and psychological mechanisms that may be responsible for the effect are identified.
718 citations
TL;DR: In this article, a spatial multi-agent programming model was developed for assessing policy options in the diffusion of innovations and resource use changes in an agricultural region in Chile, where the individual choice of the farm-household among available production, consumption, investment and marketing alternatives is represented in recursive linear programming models.
714 citations
TL;DR: Recorded depth-EEG from within the MTL of epilepsy patients performing a memorization task suggested that effective declarative memory formation is accompanied by a direct and temporarily limited cooperation between both MTL substructures.
Abstract: In humans, distinct processes within the hippocampus and rhinal cortex support declarative memory formation But do these medial temporal lobe (MTL) substructures directly cooperate in encoding new memories? Phase synchronization of gamma-band electroencephalogram (EEG) oscillations (around 40 Hz) is a general mechanism of transiently connecting neural assemblies We recorded depth-EEG from within the MTL of epilepsy patients performing a memorization task Successful as opposed to unsuccessful memory formation was accompanied by an initial elevation of rhinal-hippocampal gamma synchronization followed by a later desynchronization, suggesting that effective declarative memory formation is accompanied by a direct and temporarily limited cooperation between both MTL substructures
705 citations
TL;DR: Genetically engineered nisin variants are used to identify the structural requirements for the interaction of the peptide with lipid II, and the remaining in vivo activity is found to result from the unaltered capacity of the mutated peptide to bind to lipid II and thus to inhibit its incorporation into the peptidoglycan network.
TL;DR: The effects of modulation of transmitter release by cannabinoids in both the CNS and the PNS of various species, including humans, will be discussed.
TL;DR: In vitro and in vivo, extracellularly orientated ceramide, released upon CD95-triggered translocation of ASM to the plasma membrane outer surface, enabled clustering of CD95 in sphingolipid-rich membrane rafts and apoptosis induction.
TL;DR: PLA, which is a well-known biodegradable material, showed a good mid-term biocompatibility in the treatment of experimental arterio-venous-fistulae (AVF) and may be a material suitable for coating endovascular stents.
Abstract: Poly-Lactic-Acid (PLA) was evaluated for coating of vascular endoprostheses in the treatment of experimental arterio-venous-fistulae (AVF). Bilateral carotid – external jugular AVF were created in 5 adult dogs. 7 PLA coated nitinol stents were placed via a transfemoral approach covering 5 AVF. The contralateral AVF remained untreated. Angiography was performed immediately after stent placement, at weeks 1 and 3 and at months 3, 6 and 9. All grafts were removed and underwent histologic examination. In 2 cases the occlusion of the AVF was successful, while misplacement occurred in 3 cases. Occlusion of the parent vessel was disclosed in 3 cases. Histologic examination revealed a mild inflammatory reaction with the presence of macrophages. There was no foreign-body reaction or fragmentation of the arterial vessel wall. PLA, which is a well-known biodegradable material, showed a good mid-term biocompatibility. Elastic mismatch of the non-elastic coating and the self-expandable nitinol stent caused misplacement. Frequent vessel-occlusions were probably due to PLA-filaments fraying into the vessel lumen. Using a different textile structure PLA might be a material suitable for coating endovascular stents.
Poly-Laktid zur Ummantelung von Gefasprothesen: erste tierexperimentelle Ergebnisse in der Behandlung arterio-venoser Gefaskurzschlusse
In der vorliegenden Arbeit wurden mit Poly-Laktid ummantelte Gefasprothesen in der Behandlung von experimentell angelegten arterio-venosen Gefaskurzschlussen getestet. Gefaskurzschlussverbindungen der Halsarterien mit der parallel dazu verlaufenden, tiefen Halsvene wurden in 5 Hunden operativ angelegt. 7 mit Poly-Laktid ummantelte Gefasprothesen aus Nitinol wurden in jeweils eine Halsarterie implantiert, so dass die Gefaskurzschlussverbindung vollstandig uberdeckt war. Die gegenuberliegende Seite verblieb als Kontrolle unbehandelt. Radiologische Gefasdarstellungen erfolgten unmittelbar nach Implantation der Gefasprothese, nach 1 und 3 Wochen sowie nach 3, 6 und 9 Monaten. Alle Prothesen wurden operativ entfernt und feingeweblich untersucht. Ein erfolgreicher Verschluss der Kurzschlussverbindung gelang lediglich in 2 Fallen. In den 3 ubrigen Fallen kam es zu einer Fehlplatzierung der Gefasprothese. Gefasverschlusse der geschienten Arterien wurden in 3 Fallen beobachtet. Die feingewebliche Untersuchung zeigte geringe, entzundliche Zellreaktionen. Fremdkorperreaktionen bzw. Destruktionen der Gefaswand wurden nicht beobachtet. Mittelfristig zeigte Poly-Laktid, ein biologisch abbaubares Material, eine gute Biokompatibilitat. Das Missverhaltnis zwischen der nichtelastischen Poly-Laktid Ummantelung und der elastischen Gefasprothese erschwerte die zielgenaue, endovaskulare Platzierung. Wahrscheinlich verursachten die endstandigen Auffaserungen der Poly-Laktid-Ummantelung die haufigen Gefasverschlusse. Unter Verwendung anderer Webstrukturen konnte Poly-Laktid ein interessantes Material zur Ummantelung von Gefasprothesen sein.
TL;DR: It was found that lacZ expression was primarily limited to the central nervous system, but therein was widespread in neurons and ependyma, suggesting that the hGFAP promoter is active in a multi‐potential neural stem cell.
Abstract: With the goal of performing astrocyte-specific modification of genes in the mouse, we have generated a transgenic line expressing Cre recombinase under the control of the human glial fibrillary acidic protein (hGFAP) promoter Activity was monitored by crossing the hGFAP-cre transgenics with either of two reporter lines carrying a lacZ gene whose expression requires excision of loxP-flanked stop sequences We found that lacZ expression was primarily limited to the central nervous system, but therein was widespread in neurons and ependyma Cell types within the brain that notably failed to activate lacZ expression included Purkinje neurons of the cerebellum and choroid plexus epithelium Onset of Cre expression began in the forebrain by e135, suggesting that the hGFAP promoter is active in a multi-potential neural stem cell
TL;DR: Interconversion between these two forms of energy suggests on-site utilization of hydrogen to generate electricity, with the electrical power grid serving in energy transportation, distribution utilization, and hydrogen regeneration as needed.
Abstract: Hydrogen gas is thought to be the ideal fuel for a world in which air pollution has been alleviated, global warming has been arrested, and the environment has been protected in an economically sustainable manner. Hydrogen and electricity could team to provide attractive options in transportation and power generation. Interconversion between these two forms of energy suggests on-site utilization of hydrogen to generate electricity, with the electrical power grid serving in energy transportation, distribution utilization, and hydrogen regeneration as needed. A challenging problem in establishing H2 as a source of energy for the future is the renewable and environmentally friendly generation of large quantities of H2 gas. Thus, processes that are presently conceptual in nature, or at a developmental stage in the laboratory, need to be encouraged,
TL;DR: It is demonstrated that CHIP is a bona fide ubiquitin ligase and indicated that U-box-containing proteins may comprise a new family of E3s, and a major target of the ubiquit in ligase activity ofCHIP is Hsc70 itself.
TL;DR: It is indicated that maintaining spontaneous breathing during APRV requires less sedation and improves cardiopulmonary function, presumably by recruiting nonventilated lung units, requiring a shorter duration of ventilatory support and ICU stay.
Abstract: Improved gas exchange has been observed during spontaneous breathing with airway pressure release ventilation (APRV) as compared with controlled mechanical ventilation. This study was designed to determine whether use of APRV with spontaneous breathing as a primary ventilatory support modality better prevents deterioration of cardiopulmonary function than does initial controlled mechanical ventilation in patients at risk for acute respiratory distress syndrome (ARDS). Thirty patients with multiple trauma were randomly assigned to either breathe spontaneously with APRV (APRV Group) (n = 15) or to receive pressure-controlled, time-cycled mechanical ventilation (PCV) for 72 h followed by weaning with APRV (PCV Group) (n = 15). Patients maintained spontaneous breathing during APRV with continuous infusion of sufentanil and midazolam (Ramsay sedation score [RSS] of 3). Absence of spontaneous breathing (PCV Group) was induced with sufentanil and midazolam (RSS of 5) and neuromuscular blockade. Primary use of APRV was associated with increases (p < 0.05) in respiratory system compliance (CRS), arterial oxygen tension (PaO2), cardiac index (CI), and oxygen delivery (DO2), and with reductions (p < 0.05) in venous admixture (QVA/QT), and oxygen extraction. In contrast, patients who received 72 h of PCV had lower CRS, PaO2, CI, DO2, and Q VA/Q T values (p < 0.05) and required higher doses of sufentanil (p < 0.05), midazolam (p < 0.05), noradrenalin (p < 0.05), and dobutamine (p < 0.05). CRS, PaO2), CI and DO2 were lowest (p < 0.05) and Q VA/Q T was highest (p < 0.05) during PCV. Primary use of APRV was consistently associated with a shorter duration of ventilatory support (APRV Group: 15 +/- 2 d [mean +/- SEM]; PCV Group: 21 +/- 2 d) (p < 0.05) and length of intensive care unit (ICU) stay (APRV Group: 23 +/- 2 d; PCV Group: 30 +/- 2 d) (p < 0.05). These findings indicate that maintaining spontaneous breathing during APRV requires less sedation and improves cardiopulmonary function, presumably by recruiting nonventilated lung units, requiring a shorter duration of ventilatory support and ICU stay.
TL;DR: Fibrin clots targeted in vitro with paramagnetic nanoparticles presented a highly detectable, homogeneous T1-weighted contrast enhancement that improved with increasing gadolinium level, suggesting that molecular imaging of fibrin-targeted param magnetic nanoparticles can provide sensitive detection and localization offibrin.
Abstract: Background Molecular imaging of thrombus within fissures of vulnerable atherosclerotic plaques requires sensitive detection of a robust thrombus-specific contrast agent. In this study, we report the development and characterization of a novel ligand-targeted paramagnetic molecular imaging agent with high avidity for fibrin and the potential to sensitively detect active vulnerable plaques. Methods and Results The nanoparticles were formulated with 2.5 to 50 mol% Gd-DTPA-BOA, which corresponds to >50 000 Gd3+ atoms/particle. Paramagnetic nanoparticles were characterized in vitro and evaluated in vivo. In contradistinction to traditional blood-pool agents, T1 relaxation rate as a function of paramagnetic nanoparticle number was increased monotonically with Gd-DTPA concentration from 0.18 mL · s−1 · pmol−1 (10% Gd-DTPA nanoparticles) to 0.54 mL · s−1 · pmol−1 for the 40 mol% Gd-DTPA formulations. Fibrin clots targeted in vitro with paramagnetic nanoparticles presented a highly detectable, homogeneous T1-weigh...
TL;DR: In this article, it is suggested to elaborate a sulphur test in field experiments with the most sensitive crop in rotation, like oilseed rape, to assist in identifying S deficiencies.
TL;DR: In this paper, the authors compared intensive, extensified and organic grassland farming in southern Germany by process life cycle assessment, and found that organic farms had clear advantages in the indicators of grassland species, grazing cattle, layout of farmstead and herd management, but indices in these categories showed a wide range and are partly independent of the farming system.
TL;DR: Better knowledge of the biochemical pathways of neurosteroidogenesis and their actions on the brain seems to open new perspectives in the understanding of the physiology of the human brain as well as in the pharmacological treatment of its disturbances.
Abstract: This review summarizes the current knowledge of the biosynthesis of neurosteroids in the human brain, the enzymes mediating these reactions, their localization and the putative effects of neurosteroids. Molecular biological and biochemical studies have now firmly established the presence of the steroidogenic enzymes cytochrome P450 cholesterol side-chain cleavage (P450SCC), aromatase, 5alpha-reductase, 3alpha-hydroxysteroid dehydrogenase and 17beta-hydroxysteroid dehydrogenase in human brain. The functions attributed to specific neurosteroids include modulation of gamma-aminobutyric acid A (GABAA), N-methyl-d-aspartate (NMDA), nicotinic, muscarinic, serotonin (5-HT3), kainate, glycine and sigma receptors, neuroprotection and induction of neurite outgrowth, dendritic spines and synaptogenesis. The first clinical investigations in humans produced evidence for an involvement of neuroactive steroids in conditions such as fatigue during pregnancy, premenstrual syndrome, post partum depression, catamenial epilepsy, depressive disorders and dementia disorders. Better knowledge of the biochemical pathways of neurosteroidogenesis and their actions on the brain seems to open new perspectives in the understanding of the physiology of the human brain as well as in the pharmacological treatment of its disturbances.
TL;DR: Functional convergence has allowed proteins with different architectures to trigger a conserved conformational shift in Hsp70 that leads to nucleotide exchange.
Abstract: Bag (Bcl2-associated athanogene) domains occur in a class of cofactors of the eukaryotic chaperone 70-kilodalton heat shock protein (Hsp70) family. Binding of the Bag domain to the Hsp70 adenosine triphosphatase (ATPase) domain promotes adenosine 5'-triphosphate-dependent release of substrate from Hsp70 in vitro. In a 1.9 angstrom crystal structure of a complex with the ATPase of the 70-kilodalton heat shock cognate protein (Hsc70), the Bag domain forms a three-helix bundle, inducing a conformational switch in the ATPase that is incompatible with nucleotide binding. The same switch is observed in the bacterial Hsp70 homolog DnaK upon binding of the structurally unrelated nucleotide exchange factor GrpE. Thus, functional convergence has allowed proteins with different architectures to trigger a conserved conformational shift in Hsp70 that leads to nucleotide exchange.
21 May 2001
TL;DR: A sample-based variant of joint probabilistic data association filters is introduced to track features originating from individual objects and to solve the correspondence problem between the detected features and the filters.
Abstract: One of the goals in the field of mobile robotics is the development of mobile platforms which operate in populated environments and offer various services to humans. For many tasks it is highly desirable that a robot can determine the positions of the humans in its surrounding. In this paper we present a method for tracking multiple moving objects with a mobile robot. We introduce a sample-based variant of joint probabilistic data association filters to track features originating from individual objects and to solve the correspondence problem between the detected features and the filters. In contrast to standard methods, occlusions are handled explicitly during data association. The technique has been implemented and tested on a real robot. Experiments carried out in a typical office environment show that the method is able to track multiple persons even when the trajectories of two people are crossing each other.
TL;DR: In this paper, the authors start from the assumption that both, the localised cluster of advertising agencies in the advertising village (the "Village" and the global communications group (the 'Group'), share basic principles of social organisation.
Abstract: In the 1980s, the hegemony of the large US advertising networks has been challenged by a new breed of London-based agencies who pioneered what is known in the trade as ‘second wave’. On the one hand, second wave implied the emancipation of Soho from an ‘outpost of Madison Avenue’ to the ‘advertising village’ on the basis of momentous product and process innovations. On the other hand, a few London agencies rose to global top positions on the crest of the second wave by transforming themselves from international advertising networks into global communication groups. This paper starts from the assumption that both, the localised cluster of advertising agencies in the advertising village (the ‘Village’) and the global communications group (the ‘Group’), share basic principles of social organisation. It aims at demonstrating that the organisational logic of both the Village and the Group can be conceptualised in terms of a heterarchy. By drawing on case-study evidence from Soho on the one hand and from the wo...
TL;DR: A general role for some members of this family in polarized plant growth processes is reported and a general function of AtRop GTPases in tip growth and in polar diffuse growth is demonstrated.
Abstract: Plants contain a novel unique subfamily of Rho GTPases, vital components of cellular signalling networks. Here we report a general role for some members of this family in polarized plant growth processes. We show that Arabidopsis AtRop4 and AtRop6 encode functional GTPases with similar intrinsic GTP hydrolysis rates. We localized AtRop proteins in root meristem cells to the cross-wall and cell plate membranes. Polar localization of AtRops in trichoblasts specifies the growth sites for emerging root hairs. These sites were visible before budding and elongation of the Arabidopsis root hair when AtRops accumulated at their tips. Expression of constitutively active AtRop4 and AtRop6 mutant proteins in root hairs of transgenic Arabidopsis plants abolished polarized growth and delocalized the tip-focused Ca2+ gradient. Polar localization of AtRops was inhibited by brefeldin A, but not by other drugs such as latrunculin B, cytochalasin D or caffeine. Our results demonstrate a general function of AtRop GTPases in tip growth and in polar diffuse growth.
TL;DR: Characterizing the chaperone cofactors BAG-1 and CHIP gained insight into the cooperation of the molecular chaperones Hsc70 and Hsp70 with the ubiquitin/proteasome system, a major system for protein degradation in eukaryotic cells.
TL;DR: Human absence epilepsy can be associated with dysfunction of the brain P/Q-type voltage-gated Ca(2+) channel, and the phenotype in this patient has striking parallels with the mouse absence epilepsy models.
TL;DR: In this article, the authors generalize Lada et al. (1994) Nice technique to map dust column density through a molecular cloud to an optimized multi-band technique that can be applied to any multiuser survey of molecular clouds and show that when compared to Nice, the optimized Nicer (i) achieves the same extinction peak values, (ii) improves the noise variance of the map by a factor of 2 and (iii) is able to reach 3σ dust extinction measurements as low as A V ≃ 0.5 magnitudes.
Abstract: We generalize Lada et al. (1994) Nice technique to map dust column density through a molecular cloud to an optimized multi-band technique that can be applied to any multi-band survey of molecular clouds. We present a first application to a ~ 625 deg2 subset of the Two Micron All Sky Survey (2MASS) data and show that when compared to Nice, the optimized Nicer (i) achieves the same extinction peak values, (ii) improves the noise variance of the map by a factor of 2 and (iii) is able to reach 3σ dust extinction measurements as low as A V ≃ 0.5 magnitudes, better than or equivalent to classical optical star count techniques and below the threshold column density for the formation of CO.
TL;DR: Some important features of motors and their (potential) realization in simpler artificial model systems are discussed, that is, the molecular mobility of mechanically bound molecules, the importance of chirality for unidirectional motion, the sources of energy for driving the rotation, and the potential of using membranes and surfaces for ordering a large number of devices to achieve macroscopic effects.
Abstract: ATP synthase represents a machine at the molecular level which couples the rotation of an axle in a wheel with the endergonic production of ATP, the general source of chemical energy in the cell. The natural system prototypically bears all features of a macroscopic motor: a rotor within a stator held by a membrane and fueled by a difference in chemical potential in the form of a proton gradient combined with a machine for ATP production. The assembly of axle and wheel to a rotor device reminds one very much of a rotaxane. In this Account, we discuss some important features of motors and their (potential) realization in simpler artificial model systems, that is, the molecular mobility of mechanically bound molecules, the importance of chirality for unidirectional motion, the sources of energy for driving the rotation, and the potential of using membranes and surfaces for ordering a large number of devices to achieve macroscopic effects.