Showing papers by "ETH Zurich published in 1998"
27 Sep 1998
TL;DR: In this paper an extensive, quantitative comparison is presented, applying four multiobjective evolutionary algorithms to an extended 0/1 knapsack problem.
Abstract: Since 1985 various evolutionary approaches to multiobjective optimization have been developed, capable of searching for multiple solutions concurrently in a single run. But the few comparative studies of different methods available to date are mostly qualitative and restricted to two approaches. In this paper an extensive, quantitative comparison is presented, applying four multiobjective evolutionary algorithms to an extended 0/1 knapsack problem.
2,401 citations
Proceedings Article•
24 Aug 1998TL;DR: It is shown formally that partitioning and clustering techniques for similarity search in HDVSs exhibit linear complexity at high dimensionality, and that existing methods are outperformed on average by a simple sequential scan if the number of dimensions exceeds around 10.
Abstract: For similarity search in high-dimensional vector spaces (or ‘HDVSs’), researchers have proposed a number of new methods (or adaptations of existing methods) based, in the main, on data-space partitioning. However, the performance of these methods generally degrades as dimensionality increases. Although this phenomenon-known as the ‘dimensional curse’-is well known, little or no quantitative a.nalysis of the phenomenon is available. In this paper, we provide a detailed analysis of partitioning and clustering techniques for similarity search in HDVSs. We show formally that these methods exhibit linear complexity at high dimensionality, and that existing methods are outperformed on average by a simple sequential scan if the number of dimensions exceeds around 10. Consequently, we come up with an alternative organization based on approximations to make the unavoidable sequential scan as fast as possible. We describe a simple vector approximation scheme, called VA-file, and report on an experimental evaluation of this and of two tree-based index methods (an R*-tree and an X-tree).
1,744 citations
1,723 citations
23 Aug 1998
TL;DR: In this paper, a new public key cryptosystem is proposed and analyzed, which is provably secure against adaptive chosen ciphertext attack under standard intractability assumptions. But the scheme is quite practical, and is not provable to be used in practice.
Abstract: A new public key cryptosystem is proposed and analyzed. The scheme is quite practical, and is provably secure against adaptive chosen ciphertext attack under standard intractability assumptions. There appears to be no previous cryptosystem in the literature that enjoys both of these properties simultaneously.
1,373 citations
Journal Article•
TL;DR: In this article, a new public key cryptosystem is proposed and analyzed, which is provably secure against adaptive chosen ciphertext attack under standard intractability assumptions. But the scheme is quite practical, and is not provable to be used in practice.
Abstract: A new public key cryptosystem is proposed and analyzed. The scheme is quite practical, and is provably secure against adaptive chosen ciphertext attack under standard intractability assumptions. There appears to be no previous cryptosystem in the literature that enjoys both of these properties simultaneously.
1,228 citations
TL;DR: The Baseline Surface Radiation Network (BSRN) as mentioned in this paper is a new radiometric network, which is designed to provide validation material for satellite radiometry and climate models, and further aims at detecting long-term variations in irradiances at the earth's surface.
Abstract: To support climate research, the World Climate Research Programme (WCRP) initiated a new radiometric network, the Baseline Surface Radiation Network (BSRN). The network aims at providing validation material for satellite radiometry and climate models. It further aims at detecting long-term variations in irradiances at the earth’s surface, which are believed to play an important role in climate change. The network and its instrumentation are designed 1) to cover major climate zones, 2) to provide the accuracy required to meet the objectives, and 3) to ensure homogenized standards for a long period in the future. The limits of the accuracy are defined to reach these goals. The suitable instruments and instrumentations have been determined and the methods for observations and data management have been agreed on at all stations. Measurements of irradiances are at 1 Hz, and the 1-min statistics (mean, standard deviation, and extreme values) with quality flags are stored at a centralized data archive at the WCRP’s World Radiation Monitoring Center (WRMC) in Zurich, Switzerland. The data are quality controlled both at stations and at the WRMC. The original 1-min irradiance statistics will be stored at the WRMC for 10 years, while hourly mean values will be transferred to the World Radiation Data Center in St. Petersburg, Russia. The BSRN, consisting of 15 stations, covers the earth’s surface from 80°N to 90°S, and will soon be joined by seven more stations. The data are available to scientific communities in various ways depending on the communication environment of the users. The present article discusses the scientific base, organizational and technical aspects of the network, and data retrieval methods; shows various application possibilities; and presents the future tasks to be accomplished.
880 citations
TL;DR: A new precipitation climatology covering the European Alps is presented in this article, which is based on observations at one of the densest rain-gauge networks over complex topography world-wide, embracing more than 6600 stations from the high-resolution networks of the Alpine countries.
Abstract: A new precipitation climatology covering the European Alps is presented. The analysis covers the entire mountain range including adjacent foreland areas and exhibits a resolution of about 25 km. It is based on observations at one of the densest rain-gauge networks over complex topography world-wide, embracing more than 6600 stations from the high-resolution networks of the Alpine countries. The climatology is determined from daily analyses of bias-uncorrected, quality controlled data for the 20 year period 1971‐1990. The daily precipitation fields were produced with an advanced distance-weighting scheme commonly adopted for the analysis of precipitation on a global scale. The paper describes the baseline seasonal means derived from the daily analysis fields. The results depict the mesoscale distribution of the Alpine precipitation climate, its relations to the topography, and its seasonal cycle. Gridded analysis results are also provided in digital form. The most prominent Alpine effects include the enhancement of precipitation along the Alpine foothills, and the shielding of the inner-Alpine valleys. A detailed analysis along a section across the Alps also demonstrates that a simple precipitation‐height relationship does not exist on the Alpine scale, because much of the topographic signal is associated with slope and shielding rather than height effects. Although systematic biases associated with the rain-gauge measurement and the topographic clustering of the stations are not corrected for, a qualitative validation of the results, using existing national climatologies shows good agreement on the mesoscale. Furthermore a comparison is made between the present climatology and the Alpine sections of the global climatology of Legates and Willmott and the Greater European climatology from the Climate Research Unit (University of East Anglia). Results indicate that the pattern and magnitude of analysed Alpine precipitation critically depend upon the density of available observations and the analysis procedure adopted. © 1998 Royal Meteorological Society.
841 citations
TL;DR: In this article, it was shown that if we drop in this theorem the local boundedness assumption on S, the theorem remains true if we replace the term equivalent local martingale measure by the terms equivalent sigma-martingale measures, and the duality results which we obtained earlier are also extended to the non locally bounded case.
Abstract: The Fundamental Theorem of Asset Pricing states - roughly speaking - that the absence of arbitrage possibilities for a stochastic process S is equivalent to the existence of an equivalent martingale measure for S. It turns out that it is quite hard to give precise and sharp versions of this theorem in proper generality, if one insists on modifying the concept of "no arbitrage" as little as possible. It was shown in [DS94] that for a locally bounded R^d-valued semi-martingale S the condition of No Free Lunch with Vanishing Risk is equivalent to the existence of an equivalent local martingale measure for the process S. It was asked whether the local boundedness assumption on S may be dropped. In the present paper we show that if we drop in this theorem the local boundedness assumption on S the theorem remains true if we replace the term equivalent local martingale measure by the term equivalent sigma-martingale measure. The concept of sigma-martingales was introduced by Chou and Emery - under the name of "semimartingales de la classe (Sigma_m)". We provide an example which shows that for the validity of the theorem in the non locally bounded case it is indeed necessary to pass to the concept of sigma-martingales. On the other hand, we also observe that for the applications in Mathematical Finance the notion of sigma-martingales provides a natural framework when working with non locally bounded processes S. The duality results which we obtained earlier are also extended to the non locally bounded case. As an application we characterize the hedgeable elements. (author's abstract)
725 citations
01 Oct 1998
TL;DR: Two new algorithms for solving the least cost matching filter problem at high speeds are described, based on a grid-of-tries construction and works optimally for processing filters consisting of two prefix fields using linear space.
Abstract: In Layer Four switching, the route and resources allocated to a packet are determined by the destination address as well as other header fields of the packet such as source address, TCP and UDP port numbers. Layer Four switching unifies firewall processing, RSVP style resource reservation filters, QoS Routing, and normal unicast and multicast forwarding into a single framework. In this framework, the forwarding database of a router consists of a potentially large number of filters on key header fields. A given packet header can match multiple filters, so each filter is given a cost, and the packet is forwarded using the least cost matching filter.In this paper, we describe two new algorithms for solving the least cost matching filter problem at high speeds. Our first algorithm is based on a grid-of-tries construction and works optimally for processing filters consisting of two prefix fields (such as destination-source filters) using linear space. Our second algorithm, cross-producting, provides fast lookup times for arbitrary filters but potentially requires large storage. We describe a combination scheme that combines the advantages of both schemes. The combination scheme can be optimized to handle pure destination prefix filters in 4 memory accesses, destination-source filters in 8 memory accesses worst case, and all other filters in 11 memory accesses in the typical case.
625 citations
TL;DR: The present paper shows that the implementation of transverse relaxation-optimized spectroscopy ([15N,1H]-TROSY) into triple resonance experiments results in several-fold improved sensitivity for 2H/13C/ 15N-labeled proteins and approximately twofold sensitivity gain for 13C/15N- labeled proteins.
Abstract: The NMR assignment of 13C, 15N-labeled proteins with the use of triple resonance experiments is limited to molecular weights below ∼25,000 Daltons, mainly because of low sensitivity due to rapid transverse nuclear spin relaxation during the evolution and recording periods. For experiments that exclusively correlate the amide proton (1HN), the amide nitrogen (15N), and 13C atoms, this size limit has been previously extended by additional labeling with deuterium (2H). The present paper shows that the implementation of transverse relaxation-optimized spectroscopy ([15N,1H]-TROSY) into triple resonance experiments results in several-fold improved sensitivity for 2H/13C/15N-labeled proteins and approximately twofold sensitivity gain for 13C/15N-labeled proteins. Pulse schemes and spectra recorded with deuterated and protonated proteins are presented for the [15N, 1H]-TROSY-HNCA and [15N, 1H]-TROSY-HNCO experiments. A theoretical analysis of the HNCA experiment shows that the primary TROSY effect is on the transverse relaxation of 15N, which is only little affected by deuteration, and predicts sensitivity enhancements that are in close agreement with the experimental data.
613 citations
TL;DR: A large repertoire of functional antibodies with similar properties was produced by appending short variable complementarity-determining region 3 (CDR3) onto the two antibody germ line segments most frequently found in human antibodies by concentrating sequence diversity in regions of the antibody structure that are centrally located in the antigen binding site.
TL;DR: In this article, the relationship between radio emission and energetic photon emissions has been clarified, as well as energy release in flare-like phenomena (microflares, nanoflares) and their bearing on coronal heating.
Abstract: Radio emission from solar flares offers a number of unique diagnostic tools to address long-standing questions about energy release, plasma heating, particle acceleration, and particle transport in magnetized plasmas. At millimeter and centimeter wavelengths, incoherent gyrosynchrotron emission from electrons with energies of tens of kilo electron volts to several mega electron volts plays a dominant role. These electrons carry a significant fraction of the energy released during the impulsive phase of flares. At decimeter and meter wavelengths, coherent plasma radiation can play a dominant role. Particularly important are type III and type III‐like radio bursts, which are due to upward- and downwarddirected beams of nonthermal electrons, presumed to originate in the energy release site. With the launch of Yohkohand the Compton Gamma-Ray Observatory , the relationship between radio emission and energetic photon emissions has been clarified. In this review, recent progress on our understanding of radio emission from impulsive flares and its relation to X-ray emission is discussed, as well as energy release in flare-like phenomena (microflares, nanoflares) and their bearing on coronal heating.
TL;DR: The high-resolution X-ray structure of the nucleosome core particle, as well as earlier evidence, suggests that the histone tails are largely responsible for the assembly of nucleosomes into chromatin fibers and implies that the physiological effects of histone acetylation may be achieved by modulation of a dynamic inter-conversion between the fiber and a less condensed nucleofilament structure.
TL;DR: It is demonstrated that the polar surface area of a drug can be used as a suitable descriptor for the drugs' H-bonding potential, which offers a modern basis for property-based design and targeting of CNS drugs.
Abstract: The influence of physicochemical properties, including lipophilicity, H-bonding capacity and molecular size and shape descriptors on brain uptake has been investigated using a selection of marketed CNS and CNS-inactive drugs. It is demonstrated that the polar surface area of a drug can be used as a suitable descriptor for the drugs' H-bonding potential. A combination of a H-bonding and a molecular size descriptor, i.e., the major components of lipophilicity and permeability, avoiding knowledge of distribution coefficients, is proposed to estimate brain penetration potential of new drug candidates. Previously reported experimental surface activity data appear to be strongly correlated to molecular size of the drug compounds. Present analysis offers a modern basis for property-based design and targeting of CNS drugs.
TL;DR: The early Cretaceous carbonate carbon isotope record is marked by three positive high-amplitude (> 1.5‰) excursions each covering time spans of more than 106 years as discussed by the authors.
TL;DR: It is concluded that local adaptation is an average phenomenon that requires adequate replication at the appropriate level, that at which the local processes occur, and variable selection pressure and stochasticity may obscure local processes or change the level at which local adaptation occurs.
Abstract: In host-parasite coevolutionary arms races, parasites probably have an evolutionary advantage. Parasite populations should be locally adapted, having higher mean fitness on sympatric than allopatric hosts. Here we assess evidence for local parasite advantage. Further we investigate how adaptation and counter-adaptation of parasites and hosts, necessarily occurring in sympatry, can generate a pattern of local adaptation. Already simple frequency-dependent selection models generate complex patterns of parasite performance on sympatric and allopatric populations. In metapopulations, with extinction, recolonization, and gene flow, variable selection pressure and stochasticity may obscure local processes or change the level at which local adaptation occurs. Alternatively, gene flow may introduce adaptive variation, so differential migration rates can modify the asymmetry of host and parasite evolutionary rates. We conclude that local adaptation is an average phenomenon. Its detection requires adequate replication at the appropriate level, that at which the local processes occur.
TL;DR: Recent studies have uncovered the existence of an alternative, non-mevalonate pathway for the formation of isopentenyl pyroph phosphate and dimethylallyl pyrophosphate, the two building blocks of terpene biosynthesis.
TL;DR: An overview of the current state-of-the-art in industrial diesel control applications is given in this paper, and an outlook on possible future control issues and their role in diesel engine evolution is presented.
Abstract: This article is intended to give control engineers an overview of models and controls of diesel engines. The main emphasis is on the engine's torque generation, including all necessary ancillary devices (turbocharger, injection-system, etc.), pollutant emission and model-based controls. The paper gives a brief introduction of the basic working principles and the salient features of diesel engines and their main differences to Otto (gasoline or spark-ignited) engines are shown. The most important control tasks are then identified and their implications on engine performance are analyzed. An overview of the current state-of-the-art in industrial diesel control applications is given. It also discusses models for the simulation of transient macroscopic effects, and how these models can be simplified to be useful for controller synthesis. Finally. an outlook on possible future control issues and their role in diesel engine evolution is presented.
TL;DR: The recommendations presented here are designed to support easier communication of NMR data and NMR structures of proteins and nucleic acids through unified nomenclature and reporting standards.
Abstract: The recommendations presented here are designed to support easier communication of NMR data and NMR structures of proteins and nucleic acids through unified nomenclature and reporting standards. Much of this document pertains to the reporting of data in journal articles; however, in the interest of the future development of structural biology, it is desirable that the bulk of the reported information be stored in computer-accessible form and be freely accessible to the scientific community in standardized formats for data exchange. These recommendations stem from an IUPAC-IUBMB-IUPAB inter-union venture with the direct involvement of ICSU and CODATA. The Task Group has reviewed previous formal recommendations and has extended them in the light of more recent developments in the field of biomolecular NMR spectroscopy. Drafts of the recommendations presented here have been examined critically by more than 50 specialists in the field and have gone through two rounds of extensive modification to incorporate suggestions and criticisms.
TL;DR: The recommendations presented here are designed to support easier communication of NMR data and NMR structures of proteins and nucleic acids through unified nomenclature and reporting standards.
TL;DR: In this paper, the van der Waals parameters for the aliphatic CHn united atoms of the GROMOS96 force field were derived and adjusted to reproduce the experimental enthalpies of vaporization and vapor pressures or densities of a set of nine alkanes.
Abstract: The derivation of the van der Waals parameters for the aliphatic CHn united atoms of the GROMOS96 force field is presented. The parameters have been adjusted to reproduce the experimental enthalpies of vaporization and vapor pressures or densities of a set of nine alkanes in the liquid state at 298 K (or at the boiling point in the case of methane), using a cutoff radius for the van der Waals interactions of 1.6 nm. Force fields to be used in molecular simulations are bound to the conditions chosen for their parametrization, for example, the temperature, the densities of the systems included in the calibration set, or the cutoff radius used for the nonbonded interactions. Van der Waals parameters for the CHn united atoms of earlier GROMOS force fields were developed using a cutoff radius of 0.8 nm for the van der Waals interactions. Because the van der Waals interaction energy between aliphatic groups separated by distances between 0.8 and 1.4 nm is not negligible at liquid densities, the use of these parameters in combination with longer cutoffs leads to an overestimation of the attractive van der Waals interaction energy. The relevance of this excess attraction depends on the size of the groups that are interacting, as well as on their local densities. Free energies of hydration have been calculated for five alkanes. © 1998 John Wiley & Sons, Inc. J Comput Chem 19: 535–547, 1998
TL;DR: It is shown that after unilateral CST lesion in the adult rat brainstem, both intact and lesioned tracts show topographically appropriate sprouting after treatment with a monoclonal antibody that neutralizes these inhibitory proteins.
Abstract: Anatomical plasticity and functional recovery after lesions of the rodent corticospinal tract (CST) decrease postnatally in parallel with myelin formation. Myelin-associated neurite growth inhibitory proteins prevent regenerative fiber growth, but whether they also prevent reactive sprouting of unlesioned fibers is less clear. Here we show that after unilateral CST lesion in the adult rat brainstem, both intact and lesioned tracts show topographically appropriate sprouting after treatment with a monoclonal antibody that neutralizes these inhibitory proteins. Antibody-treated animals showed full recovery in motor and sensory tests, whereas untreated lesioned rats exhibited persistent severe deficits. Neutralization of myelin-associated neurite growth inhibitors thus restores in adults the structural plasticity and functional recovery normally found only at perinatal ages.
TL;DR: Long-standing questions on how peptides fold are addressed by the simulation at different temperatures of the reversible folding of a peptide in solution in atomic detail, implying that the search problem in peptide (or even protein) folding is surmountable using dynamics simulations.
TL;DR: The feasibility of the KEOPS concept is assessed by modeling, laboratory experiments, and testbed implementation of optical packet switching nodes and network/node interfacing blocks, including a fully equipped demonstrator.
Abstract: This paper reviews the work carried out in the ACTS KEOPS (Keys to Optical Packet Switching) project, describing the results obtained to date. The main objective of the project is the definition, development, and assessment of optical packet switching and routing networks, capable of providing transparency to the payload bit rate, using optical packets of fixed duration and low bit rate headers in order to enable easier processing at the network/node interfaces. The feasibility of the KEOPS concept is assessed by modeling, laboratory experiments, and testbed implementation of optical packet switching nodes and network/node interfacing blocks, including a fully equipped demonstrator. The demonstration relies on advanced optoelectronic components, developed within the project, which are described.
TL;DR: In this article, a simple cation exchange can be used to remove template molecules between the individual shells of the VOx nanotubes without destroying the tubes, which can then be used as template molecules to remove the template molecules.
Abstract: Unlike many small carbon nanotubes, VOx nanotubes (shown on the right) are obtained as the main product of a direct chemical synthesis at relatively low temperatures. The multiwalled material contains template molecules between the individual shells, which by a simple cation exchange can be removed without destruction of the tubes.
TL;DR: In this paper, the authors present a definition of the cross section for the production of an isolated photon plus n jets which only depends upon direct photon production, and it is independent of the parton-to-photon fragmentation contribution.
TL;DR: In this article, a system of finitely many nonrelativistic, quantum mechanical electrons bound to static nuclei is considered, and the electrons are minimally coupled to the quantized electromagnetic field; but an ultraviolet cutoff on the electromagnetic vector potential appearing in covariant derivatives, and interactions between the radiation field and electrons localized very far from the nuclei are turned off.
TL;DR: This model has been tested with experimental in vitro cultured epithelial cell (Caco-2) permeability data for structurally diverse drugs differing in lipophilicity, ionization state and molecular size, and predicts different sigmoid-hyperbolic permeability-lipophILicity relationships for different molecular weight ranges.
TL;DR: After a discussion of the physical chemistry of nitrogen monoxide, several reactions that can acts as sinks are discussed, namely the reaction with dioxygen, with thiols and with superoxide, which leads to a powerful oxidant, peroxynitrite.
TL;DR: The physical and chemical mechanism of ore precipitation in the Yankee Lode tin deposit was quantified by direct trace-element microanalysis of fluid inclusions by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS).
Abstract: The physical and chemical mechanism of ore precipitation in the Yankee Lode tin deposit (Mole Granite, Australia) was quantified by direct trace-element microanalysis of fluid inclusions. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) was used to measure element concentrations in a series of fluid inclusions representing the fluid before, during, and after the deposition of cassiterite (SnO2). Tin precipitation was driven by mixing of hot magmatic brine with cooler meteoric water. At the same time, a separate magmatic vapor phase selectively transported copper and boron into the liquid mixture.