bluuebunny/crossref_metadata_2025 huggingface dataset:
Deposit Insurance Around the Globe: Where Does It Work?
Authors: Demirgüç Aslı , Kane Edward J
Published: October 2002

Explicit deposit insurance has been spreading rapidly in recent years, even to countries with low levels of financial and institutional development. This paper documents the extent of cross-country differences in deposit insurance design and reviews empirical evidence on how particular design features affect private market discipline, banking stability, financial development and the effectiveness of crisis resolution. This evidence challenges the wisdom of encouraging countries to adopt explicit deposit insurance without first stopping to assess and remedy weaknesses in their informational and supervisory environments.
Saudi Arabia: Petroleum Industry Review
Authors: Shammas Pierre
Published: October 2002

A comprehensive review is provided of Saudi Arabia's petroleum industry covering oil and gas exploration and production, refining, oil and gas trade, marketing and Saudi overseas investments. Profiles of key Saudi decision makers are provided.

A statistical appendix includes data from the start of oil production in Saudi Arabia in 1938. Part I Geological potential Part II The Saudi energy economy Part III Production capacity Part IV The oil refining sector Part V Exports and logistics Part VI Overseas petroleum industry investments Part VII The decision makers Part VIII Statistical Appendix; Reserves, Production, Exports, Prices 1950 to 1999.
Formation of Multiple Basins above Low Angle Detachments; A Centrifuge-Model Approach
Authors: Koyi Hemin A. , Harris Lyal B.
Published: October 2002

Extended scaled centrifuge models, simulating lithospheric deformation, show that depocenters of sedimentary basins, formed above lithospheric detachment zones, migrate both in space and time. If associated with a low-angle mantle detachment, this migration results in formation of multiple basins from a single phase of model extension. Unlike the multiple detachment model proposed for formation of multiple basins or models invoking transtensional deformation, the current analogue models suggest that multiple basins may form due to continuous displacement along one single low-angle detachment during orthogonal rifting. Model results suggest that the geometry and location of sedimentary basins are strongly dependent on the coupling between the upper crust and mantle lithosphere by the ductile lower crust, and the dip of the prescribed “fault/shear zone” in the mantle lithosphere. Steeply dipping lithospheric detachment enhances coupling and hence formation of a single basin in the upper crust above the maximum asthenospheric upwelling in the centre of the rift. In contrast, low-angle detachment in the lithosphere promotes decoupling of the upper crust and any resulting basins from the underlying mantle lithosphere. The dip angle of the mantle detachment affects both location and geometry of the basin. A low-angle shear zone in the mantle lithosphere decouples the broad sag in the upper crust, whereas a steep shear zone promotes coupling and initiates narrow, but deep basins.
Unpleasantness and Acceptable Limits of Low Frequency Sound
Authors: Inukai Yukio , Nakamura Norio , Taya Hideto
Published: October 2002

Equal unpleasantness sound pressure levels of pure tones from 10 Hz to 500Hz were obtained by the method of adjustment in which subjects adjusted sound pressure levels equating to subjective degrees of unpleasantness on a 4–steps rating scale. In addition, the maximum acceptable sound pressure levels were measured at each frequency, assuming four types of situations, that is, a living room, a bedroom, an office and a factory. It was found that the acceptable limits were equivalent to very low levels of unpleasantness in some situations. The third order polynomial models of physical variables were well fitted to the subjective response data.
Threshold of Rattling of Windows and Doors by Low Frequency Noise
Authors: Kitamura Toshiya , Takano Jun-Ichi , Imura Yosuke , Yamada Shinji
Published: October 2002

We set up a low frequency noise generation room to study the relationship between rattling phenomena and low frequency noise. Auditory thresholds and visual thresholds of rattling phenomena were measured for six kinds of Japanese and European doors. This paper describes the thresholds of rattling phenomenon for these doors, especially the Shoji (a thin paper pasted sliding door) and the Garasudo (a sliding door with glass panels). This study shows a relationship between the rattling thresholds and the resonance frequencies, changes of these thresholds according to the seasons and differences between auditory threshold curves and visual threshold curves.
Modelling and Open-Loop Control of a Single-Link Flexible Manipulator with Neural Networks
Authors: Shaheed M. H. , Tokhi M. O.
Published: October 2002

This paper presents an investigation into the development of open-loop control strategies using shaped command inputs with neural networks for vibration suppression in flexible manipulator systems. The method requires, at the first stage, that the natural vibration frequencies of the system be determined. A non-linear AutoRegressive process with eXogenous inputs (NARX) model is used with multi-layered perceptron (MLP) and radial basis function (RBF) neural networks for this purpose. Shaped command inputs including low-pass and band-stop filtered torque input functions are then developed based on the identified modes of vibration and applied to a single-link manipulator in an open-loop configuration to suppress the system vibrations. The performance of the control strategy in suppressing the system vibrations is assessed in comparison to a bang-bang torque input. Finally, a comparative performance assessment of the low-pass and band-stop filtering approaches in suppressing system vibrations is presented.
On the Adsorption of Chromium(VI) Ions on Dolomite and ‘Dolomitic Sorbents’
Authors: Stefaniak Elżbieta , Dobrowolski Ryszard , Staszczuk Piotr
Published: October 2002

The sorption capability of raw and thermally treated dolomite samples with respect to toxic ions was estimated through the adsorption of chromium(VI) from aqueous solutions. The adsorption isotherms were shown to fit the well-known Freundlich equation. The results confirm the weak adsorption of chromium(VI) on raw dolomite relative to the other dolomite-derived sorbents. The influence of ionic strength on the adsorption was also determined.
Effect of Cationic, Non-Ionic and Anionic Surfactants on the Adsorption of Carbofuran on Three Different Types of Indian Soil
Authors: Singh R.P. , Rawat J.P. , Kumar Raj
Published: October 2002

The adsorption of carbofuran in aqueous surfactant-free and surfactant (cationic, non-ionic and anionic) solutions of different micellar concentration (½ × CMC, CMC and 2 × CMC) on three different types of Indian soil has been studied using the batch shaking technique. The measured equilibrium adsorption isotherms for the surfactant-free and surfactant/soil/water systems at different critical micellar concentrations were S-shaped and in close agreement to the Freundlich isotherms. Higher adsorption of carbofuran in both systems was observed on silt loam soil followed by loam and sandy soils, and was anticipated by the values obtained for the Freundlich constant, KF, and the partition coefficient, KD. The values of KF and KD obtained also confirmed that the adsorption of carbofuran in aqueous surfactant solutions followed the order cationic > nonionic > anionic at all the CMC values studied. The affinity of carbofuran towards organic matter and the clay content of the soils was evaluated by calculating the Kom and Kc values, when it was found that carbofuran adsorption was better correlated with the clay content than with the organic matter content. The predicted log Kom values were also obtained from the aqueous solubility, 1-octanol/water partition coefficient (Kow), adsorbability index (Al) and first-order molecular connectivity index (1χ) of carbofuran. Use of the aqueous solubility and the 1-octanol/water partition coefficient of carbofuran to predict the adsorption gave values with a considerable error in comparison with those measured experimentally, whereas the use of the absorbability index and first-order molecular connectivity index for carbofuran improved the predictions considerably. The results obtained are interesting in that they afford basic data relating to the possible use of surfactants for solving problems of soil contamination by carbofuran.
Dynamics of Coagulation Structure Disruption in Titanium Dioxide Dispersions
Authors: Synyts'ka A.V. , Zakordons'kyj V.P. , Soltys M.M.
Published: October 2002

The importance of the concentration factor in structurization processes and in the breakdown dynamics of aqueous TiO2 dispersions was demonstrated in the presence of anionic sodium dodecylbenzenesulphonate. A correlation was obtained between the critical concentration volume filling associated with structurization and the coordination number of the titanium(IV) dioxide dispersions. An analysis of the results obtained was made using the flow theory of aggregation systems.
Catalytic Decomposition of H2O2 over Manganese Oxides Supported on an Active Alumina
Authors: Deraz Nasr-Allah M. , El-Sayed M.A. , El-Aal A. Abd.
Published: October 2002

A series of manganese oxides loaded on to an active alumina support was prepared by impregnation methods and the resulting samples preheated in air at 400°C, 650°C or 900°C for 6 h. The amount of manganese, expressed as Mn2O3, was varied between 3.7 wt% and 55.3 wt%. The kinetics of the decomposition of H2O2 in an aqueous medium were studied in the presence of these oxides. The catalytic activities increased initially as the amounts of manganese present increased, attaining a maximum value at 13.4 wt% Mn2O3 and then decreasing on increasing both the amount of manganese above this limit and the precalcination temperature from 400°C to 900°C. The specific surface areas of the various catalysts were determined by BET analysis of the nitrogen adsorption isotherms. The SBET values varied from 244 m2/g to 80 m2/g both as a function of the extent of loading and the precalcination temperature. However, the activation energy for sintering, ΔES, increased on increasing the amount of Mn2O3 present. The apparent activation energy for H2O2 decomposition conducted over the various solids was found to be virtually unaffected by a change in the amount of manganese present.
The Use of Columns Packed with Chicken Feathers for the Removal of Phenol from Aqueous Solutions
Authors: Banat Fawzi A. , Al-Asheh Sameer
Published: October 2002

The removal of phenol from aqueous solutions by adsorption on to chicken feathers was studied experimentally using a fixed bed system, the effects of bed depth, feed flow rate and feed concentration on the breakthrough behaviour being investigated. Breakthrough curves showed the constant pattern behaviour typical of favourable isotherms, with a sharp initial breakthrough followed by a slow approach to equilibrium. The breakthrough time increased with increasing bed height, decreasing flow rate and decreasing influent concentration. Phenol uptake, however, increased with increasing feed flow rate and feed concentration. The Thomas and Bed-Depth-Service-Time (BDST) models were applied successfully to the sorptive removal of phenol.
New Optimisation Procedure for Outlet Angle of a Hawt Turbine Blade Element
Authors: Ntoko Nzumbe-Mesape
Published: October 2002

A new expression is developed for the optimum outlet blade angle of a HAWT turbine blade element using impulse turbine theory. A simple numerical scheme is then given for calculating the blade angle using a modified expression for the relative velocity coefficient. Numerical results are presented which are in good agreement with optimum values.
Comments on a Procedure for Rating High-Energy Impulsive Sounds: Analyses of Previous and New Data Sets, and Suggestions for a Revision
Authors: Vos Joos
Published: October 2002

Results from field-laboratory studies suggest that the annoyance caused by high-energy impulsive sounds increases more rapidly with sound level than the annoyance caused by vehicle passby sounds. After a further analysis of field survey data collected around, among other things, two American artillery ranges [Paul D. Schomer, Noise Control Eng. J. 42, 179–191 (1994)], it was concluded that the community response confirmed the results from the field-laboratory tests. In the present study, it is shown that this conclusion is not justified. From the results of a new more systematic re-analysis, it is concluded that the community response to high-energy impulsive artillery sounds and traffic sounds cannot be understood from the field-laboratory results mentioned above. For rating procedures which are based on sound levels determined in free-field conditions, application of the model with the previously recommended parameter values would lead to an underestimation of the rating sound level for artillery sounds by almost 15 dB. The data obtained in a new Germany field survey on the community response to artillery and road-traffic sounds were used in a supplementary analysis, which essentially confirmed the results of the re-analysis. On the basis of both the American and Germany field data, and the results from recent studies including very high blast and sonic boom levels, a provisional revised model was developed for rating artillery shooting sounds and other high-energy impulsive sounds such as sonic booms and quarry explosions.
Optimum Acoustical Conditions for Speech Intelligibility in Classrooms
Authors: Bistafa Sylvio R. , Bradley John S.
Published: October 2002

Reverberation time and the maximum background-noise level are the usual basis of classroom acoustic standards and regulations. Comparing the results provided by three speech intelligibility metrics, under the assumption of a diffuse sound field with ideal exponential decays, led to a range of estimates of optimum conditions for optimum speech intelligibility. A reverberation time of 0.4 s and a maximum background noise level 25 dB below the voice level measured at 1 m in front of the talker were indicated to lead to optimum speech intelligibility by all three speech metrics and are therefore suggested to ensure the best speech intelligibility conditions in classrooms.
Blind Source Separation Applied to Rotating Machine Monitoring and Fault Detection
Authors: Gelle Guillaume , Colas Maxime
Published: October 2002

This article presents a processing technique called “Blind Source Separation” initially developed for telecommunication applications and now applied to vibration monitoring of mechanical systems. Experimental results illustrate the potential of blind source separation as a pre-treatment to free the signal from its environment (denoising), so as to improve fault detection and diagnosis. An example of bearing faults detection on an experimental test bench is presented.
Noise Level versus Number of Citizens
Authors: Gaja E. , Sancho S. , Reig A. , Clemente G.
Published: October 2002

In this paper a resume of six years of working and researching on the evaluation of noise pollution in 56 cities of the Valencian Community (Spain) is presented. The main source of this noise pollution is due to urban traffic. The aim of this paper is to establish the possible correlation between the noise level and the official register of citizens in those cities, which are from a wide range of the population; from 1110 to 750000 inhabitants. This could be a good method to obtain conclusions whether a city has the right level of noise according to its population or, on the other hand, whether the noise level is too high or too low.
Sound Insulation of Multi-Storey Houses — A Summary of Finnish Impact Sound Insulation Results
Authors: Sipari Pekka
Published: October 2002

Evidently a wooden house can be built so that modern requirements for both airborne and impact sound insulation are met with sufficient margins. However, low-frequency impact sounds produced by walking may be either audible to the building occupants or felt by them as non-audible vibrations.

It is clear that the present rating methods and also perhaps the tapping machine are inadequate where wooden floors are concerned, because the results may be subjectively confusing. The present situation, where internationally there are several rating systems leading to different numerical results for the same building element, needs to be addressed. Existing methods should be developed into a single international method covering all types of floors. The question of how to rate low-frequency (32-100 Hz) footfall noises, which may not be simulated adequately by a tapping machine and rated with present methods, must be considered as a special problem separate from the general rating system.

It is generally recommended to add to the mass and stiffness of the wooden floor (for example, by adding a concrete layer) to improve its overall vibration and impact sound insulation behaviour. Such floors are believed to better satisfy the requirements of building occupants.
An Alternative Method for Measurement of Airborne Sound Insulation
Authors: Lundberg Karl-Ola
Published: October 2002

A method for determination of the transmission coefficient from Complex Modulation Transfer Functions CMTF:s based on measured impulse-responses is shown.

In the method a separate measurement of the equivalent sound absorption area is not needed in contrast to in the standardised measurement.

By averaging over a number of estimates of the impulse-response the influence of background noise can be reduced substantially, implying that low-power sources can be used.

A model for the power balance in the receiving room with time-varying power is considered. In the model the quotient of the receiving room intensity and the source room intensity has one pole, which is proportional to the equivalent sound absorption area in the receiving room, and a gain, proportional to the transmission coefficient.

In the physical system the power can be time-varied by letting the system excitation signal consist of random noise modulated with a deterministic time-varying function. However, since the ensemble average of the squared response is proportional to the squared impulse-response convolved with the squared modulating function, random excitation is avoided and replaced by impulse-response measurements. The quotient of intensities in the model is in the physical system a quotient of CMTF:s.

Experiments are carried out in an airborne sound insulation laboratory. For comparison, standardised measurements are also carried out. It is found that the presented method gives as result comparatively small transmission coefficients, though the relative differences are small. By refining the power balance model by introducing an energy propagation time delay, and selecting an appropriate delay, the differences were diminished.
Impact Sound Insulation: The Standard Tapping Machine Shall Learn to Walk!
Authors: Scholl W.
Published: October 2002

Previous research on the standard tapping machine has shown that the impact on a floor depends strongly on the combined system of floor and tapping hammers. This means that in general, a particular measure to reduce the impact sound pressure level can be advantageous with one impact source and disadvantageous with another. Conversion from one impact source to another has to be made for each floor individually, provided there is a sufficient knowledge of the dynamic properties of the source and floor. So, if the standard tapping machine is to be used to characterise a floor with respect to walking noise, the only simple way out of the problem is to make it ‘behave like a walker’. That means it should have the same source impedance. Investigations at the Fraunhofer-Institut für Bauphysik Stuttgart showed that this could be achieved by small modifications to the standard tapping machine. Comparisons using a concrete floor and a wooden joist floor have proved that results using such a modified tapping machine are much closer to walking noise than the results using the standard tapping machine.
Technical Note: Prediction of the Characteristics of Complicated Sound Fields in Long Enclosures by a Beam-Tracing Method
Authors: Zeng Xiangyang , Sun Jincai , Chen Ke'an
Published: October 2002

The subject of this paper is the characterisation of the sound field in long enclosures. A beam-tracing computer model has been developed especially for the simulation of sound propagation throughout long enclosures. Surface diffusing reflection and air absorption are included in the model, which can predict the impulse response and acoustic indexes at arbitrary positions in the enclosure. This paper describes how the algorithm models the sound source, sound propagation and sound receiver. The algorithm was then tested in both common rooms and long enclosures by comparison of the measurement, theoretical calculation and prediction results. The characteristics of more complex sound fields in long enclosures, the prediction of reverberation time, early decay time and sound pressure level, etc, at individual points are discussed in terms of the algorithm. The results indicate that the primary characteristics of complicated sound fields in non-rectangular long enclosures are similar to those in rectangular ones.
Dynamic Response of Complete Torospherical Shells under Internal Periodic Pressure
Authors: Sadiq Obanishola M.
Published: October 2002

The study reported here is concerned with the response of complete Torospherical shells under internal dynamic pressure. The Torospherical shell modelled from an Ellipsoidal shell consists of a combination of spherical segments joined with toroidal segments of circular cross-section. The nonlinear systems of dynamic equations formulated were solved using trigonometric projection procedures and Newton's iterative processes. Two types of torospherical shells were analysed and compared. Results show that the dynamic response of the Torospherical shells subjected to internal dynamic pressure depends not only on the frequency of dynamic pressure but specifically on the ratio of the radii of the toroidal segments to that of the spherical segments. We also discovered that if loss of dynamic stability of ellipsoidal shells is largely axisymmetrical, loss of dynamic stability of Torospherical shells is asymmetrical with formation of circular waves in the circumferential direction. The modes of vibration of the Torospherical shells are also presented.
Configurations of Braced Domes
Authors: El-Sheikh Ahmed
Published: October 2002

Braced domes may be fabricated in any of several common grid configurations. With different configurations, the dome performance varies considerably affecting both its competitiveness and suitability for specific applications. The study presented in this paper is an assessment of the most commonly adopted dome configurations and their effect on the dome characteristics such as the stiffness/weight value, member stress distribution, number of joints and members, degree of redundancy and cost. The study is parametric and covers wide variations of dome span/rise ratio and boundary conditions. The results of this study could be of significant value to the design of future braced dome structures.
Life history consequences of mammal sibling rivalry
Authors: Stockley P. , Parker G. A.
Published: October 2002

Mammal life history traits relating to growth and reproduction are extremely diverse. Sibling rivalry may contribute to selection pressures influencing this diversity, because individuals that are relatively large at birth typically have an advantage in competition for milk. However, selection for increased growth rate is likely to be constrained by kin selection and physiological costs. Here, we present and test a model examining the ESS (evolutionarily stable strategy) balance between these constraints and advantages associated with increased prenatal growth in mammal sibling rivalry. Predictions of the model are supported by results of comparative analyses for the Carnivora and Insectivora, which demonstrate an increase in prenatal growth rate with increasing intensity of postnatal scramble competition, and a decrease in postnatal growth rate relative to size at birth. Because increased prenatal growth rates are predicted to select for reduced gestation length under certain conditions, our study also indicates that sibling rivalry may contribute to selection pressures influencing variation in altriciality and precociality among mammals.
Transitive functional annotation by shortest-path analysis of gene expression data
Authors: Zhou Xianghong , Kao Ming-Chih J. , Wong Wing Hung
Published: October 2002

Current methods for the functional analysis of microarray gene expression data make the implicit assumption that genes with similar expression profiles have similar functions in cells. However, among genes involved in the same biological pathway, not all gene pairs show high expression similarity. Here, we propose that transitive expression similarity among genes can be used as an important attribute to link genes of the same biological pathway. Based on large-scale yeast microarray expression data, we use the shortest-path analysis to identify transitive genes between two given genes from the same biological process. We find that not only functionally related genes with correlated expression profiles are identified but also those without. In the latter case, we compare our method to hierarchical clustering, and show that our method can reveal functional relationships among genes in a more precise manner. Finally, we show that our method can be used to reliably predict the function of unknown genes from known genes lying on the same shortest path. We assigned functions for 146 yeast genes that are considered as unknown by the
Saccharomyces
Genome Database and by the Yeast Proteome Database. These genes constitute around 5% of the unknown yeast ORFome.
Floral responses to photoperiod are correlated with the timing of rhythmic expression relative to dawn and dusk inArabidopsis
Authors: Roden Laura C. , Song Hae-Ryong , Jackson Stephen , Morris Karl , Carre Isabelle A.
Published: October 2002

Daylength, or photoperiod, is perceived as a seasonal signal for the control of flowering of many plants. The measurement of daylength is thought to be mediated through the interaction of phototransduction pathways with a circadian rhythm, so that flowering is induced (in long-day plants) or repressed (in short-day plants) when light coincides with a sensitive phase of the circadian cycle. To test this hypothesis in the facultative long-day plant,Arabidopsis thaliana, we used varying, non-24-hr light/dark cycles to alter the timing of circadian rhythms of gene expression relative to dawn and dusk. Effects on circadian rhythms were correlated with those on flowering times. We show that conditions that displaced subjective night events, such as expression of the flowering time regulatorCONSTANSinto the light portion of the cycle, were perceived as longer days. This work demonstrates that the perception of daylength inArabidopsisrelies on adjustments of the phase angle of circadian rhythms relative to the light/dark cycle, rather than on the measurement of the absolute duration of light and darkness.
Donor-bridge-acceptor energetics determine the distance dependence of electron tunneling in DNA
Authors: Lewis Frederick D. , Liu Jianqin , Weigel Wilfried , Rettig Wolfgang , Kurnikov Igor V. , Beratan David N.
Published: October 2002

Electron transfer (ET) processes in DNA are of current interest because of their involvement in oxidative strand cleavage reactions and their relevance to the development of molecular electronics. Two mechanisms have been identified for ET in DNA, a single-step tunneling process and a multistep charge-hopping process. The dynamics of tunneling reactions depend on both the distance between the electron donor and acceptor and the nature of the molecular bridge separating the donor and acceptor. In the case of protein and alkane bridges, the distance dependence is not strongly dependent on the properties of the donor and acceptor. In contrast, we show here that the distance decay of DNA ET rates varies markedly with the energetics of the donor and acceptor relative to the bridge. Specifically, we find that an increase in the energy of the bridge states by 0.25 eV (1 eV = 1.602 × 10
−19
J) relative to the donor and acceptor energies for photochemical oxidation of nucleotides, without changing the reaction free energy, results in an increase in the characteristic exponential distance decay constant for the ET rates from 0.71 to 1.1 Å
−1
. These results show that, in the small tunneling energy gap regime of DNA ET, the distance dependence is not universal; it varies strongly with the tunneling energy gap. These DNA ET reactions fill a “missing link” or transition regime between the large barrier (rapidly decaying) tunneling regime and the (slowly decaying) hopping regime in the general theory of bridge-mediated ET processes.
Abnormal gene expression in cloned mice derived from embryonic stem cell and cumulus cell nuclei
Authors: Humpherys David , Eggan Kevin , Akutsu Hidenori , Friedman Adam , Hochedlinger Konrad , Yanagimachi Ryuzo , Lander Eric S. , Golub Todd R. , Jaenisch Rudolf
Published: October 2002

To assess the extent of abnormal gene expression in clones, we assessed global gene expression by microarray analysis on RNA from the placentas and livers of neonatal cloned mice derived by nuclear transfer (NT) from both cultured embryonic stem cells and freshly isolated cumulus cells. Direct comparison of gene expression profiles of more than 10,000 genes showed that for both donor cell types ≈4% of the expressed genes in the NT placentas differed dramatically in expression levels from those in controls and that the majority of abnormally expressed genes were common to both types of clones. Importantly, however, the expression of a smaller set of genes differed between the embryonic stem cell- and cumulus cell-derived clones. The livers of the cloned mice also showed abnormal gene expression, although to a lesser extent, and with a different set of affected genes, than seen in the placentas. Our results demonstrate frequent abnormal gene expression in clones, in which most expression abnormalities appear common to the NT procedure whereas others appear to reflect the particular donor nucleus.
A dominant-negative
MEC3
mutant uncovers new functions for the Rad17 complex and Tel1
Authors: Giannattasio Michele , Sommariva Elena , Vercillo Raffaella , Lippi-Boncambi Filippo , Liberi Giordano , Foiani Marco , Plevani Paolo , Muzi-Falconi Marco
Published: October 2002

The Rad17-Mec3-Ddc1 complex is essential for the cellular response to genotoxic agents and is thought to be important for sensing DNA lesions. Deletion of any of the
RAD17
,
MEC3
or
DDC1
genes abolishes the G
1
and G
2
and impairs the intra-S DNA-damage checkpoints. We characterize a dominant-negative
mec3-dn
mutation that has an unexpected phenotype. It inactivates the G
1
checkpoint while it leaves the G
2
response functional, thus revealing a difference in the requirements of the DNA-damage response in different phases of the cell cycle. In an attempt to identify the molecular defect imparted by the mutation, we dissected step-by-step the signaling cascade, which is triggered by DNA lesions and requires the activity of Mec1 and Rad53 kinases. The analysis of the phosphorylation state of checkpoint factors and critical protein interactions showed that, in
mec3-dn
cells, the signal transduction cascade is triggered normally, and the central kinase Mec1 can be activated. In G
1
cells expressing the mutation, the signaling cannot proceed any further along the pathway, indicating that the Rad17 complex acts after the activation of Mec1, possibly recruiting targets for the kinase. We also show that the function of the G
2
checkpoint in mutant cells is maintained by an uncharacterized activity of Tel1, the yeast homologue of ATM. This work thus reports a previously undiscovered role for Tel1 in checkpoint control.
Level detection in ion channel records via idealization by statistical filtering and likelihood optimization
Authors: Pastushenko Vassili Ph. , Schindler Hansgeorg
Published: October 2002

A parameter–free method is presented for the level detection in ion channel records via recovery of step wise current changes. No assumptions about ion channel mechanism are made. The primary detection of the transitions is made by statistical filtering the data using the Student'st–test. The event currents are calculated as the average value of the current between two adjacent transitions. An optimal ideal trace is found by maximization of a likelihood function. The distribution of event currents recovered from the raw data is then analysed, again by using the Student'st–test, for their grouping into separate statistical ensembles, defining current levels. The method is subjected to rigorous test using simulated data, and is compared with several other methods. It produces the levels of channel current, their noise amplitudes and distributions of dwell times, the desired information for constructing the channel mechanism.
A comparative study on the tubes and feeding behaviour of eight species of corophioid Amphipoda and their bearing on phylogenetic relationships within the Corophioidea
Authors: Dixon I. M. T. , Moore P. G.
Published: October 2002

Observations are presented on mouthpart functional morphology, and on feeding, grooming and defaecatory behaviour of eight species of corophioid Amphipoda, viz.Corophium bonnellii,Lembos websteri,Aora gracilis,A. spinicornis,Gammaropsis nitida,Ericthonius punctatus,Jassa falcataandJ. marmorata. These data are considered in relation to tube structure and amphipod posture in relation to the tube. All these species occupy double-ended cylindreical tubes made from ‘amphipod silk’ secreted by the third and fourth preraeopods, incorporating sediment and other debris to varying degrees. Uniquely among this set of species, however,E. punctatushas a tube that is architecturally distinct. It tapers along its length and has a distinctive oblique main entrance at its widest end. This end is used preferentially. The other species studied use either opening with equal facility. Such a feature is adaptive in facilitating deployment of the antennae and shielding the head ofE. punctatus.

Two groupings of species are propose: group A which feed inside their tube using pleopod-induced through-tube currents, and group B which feed outside or at the entrance to their tube using external water currents. Group A includesC. bonnellii,L. websteriand theAoraspecies. Group B includesE. punctatusand theJassaspecies.Gammaropsis nitidaexhibits traits from both groups, adding weight to its perceived status as a genus representative of the stem corophioid. The ischyrocerid habit of externalizing food-gathering may be regarded as the first step along an evolutionary line leading to the rod-building podocerid types and ultimately towards the caprellids. All species examined show a degree of flexibility in their feeding habits which helps to explain the success of this taxon, which has radiated into a great diversity of aquatic biotopes.
Selection versus random drift: long–term polymorphism persistence in small populations (evidence and modelling)
Authors: Nevo E. , Kirzhner V. , Beiles A. , Korol A.
Published: October 2002

Our data on a subterranean mammal,Spalax ehrenbergi, and other evidence, indicate that appreciable polymorphism can be preserved in small isolated populations consisting of several dozens of, or a hundred, individuals. Current theoretical models predict fast gene fixation in small panmictic populations without selection, mutation, or gene inflow. Using simple multilocus models, we demonstrate here that moderate stabilizing selection (with stable or fluctuating optimum) for traits controlled by additive genes could oppose random fixation in such isolates during thousands of generations. We also show that in selection–free models polymorphism persists only for a few hundred generations even under high mutation rates. Our multi-chromosome models challenge the hitchhiking hypothesis of polymorphism maintenance for many neutral loci due to close linkage with few selected loci.
Image reconstruction in optical tomography
Authors: Arridge Simon R. , Schweiger Martin
Published: October 2002

Optical tomography is a new medical imaging modality that is at the threshold of realization. A large amount of clinical work has shown the very real benefits that such a method could provide. At the same time a considerable effort has been put into theoretical studies of its probable success. At present there exist gaps between these two realms. In this paper we review some general approaches to inverse problems to set the context for optical tomography, defining both the termsforward problemandinverse problem. An essential requirement is to treat the problem in a nonlinear fashion, by using an iterative method. This in turn requires a convenient method of evaluating the forward problem, and its derivatives and variance. Photon transport models are described and methods for obtaining analytical and numerical solutions for the most commonly used ones are reviewed. The inverse problem is approached by classical gradient–based solution methods. In order to develop practical implementations of these methods, we discuss the important topic ofphoton measurement density functions, which represent the derivative of the forward problem. We show some results that represent the most complex and realistic simulations of optical tomography yet developed. We suggest, in particular, that both time–resolved, and intensity–modulated systems can reconstruct variations in both optical absorption and scattering, but that unmodulated, non–time–resolved systems are prone to severe artefact. We believe that optical tomography reconstruction methods can now be reliably applied to a wide variety of real clinical data. The expected resolution of the method is poor, meaning that it is unlikely that the type of high–resolution images seen in computed tomography or medical resonance imaging can ever be obtained. Nevertheless we strongly expect the functional nature of these images to have a high degree of clinical significance.
Population momentum and the demand on land and water resources
Authors: Fischer Günther , Heilig Gerhard K.
Published: October 2002

Future world population growth is fuelled by two components: the demographic momentum, which is built into the age composition of current populations, and changes in reproductive behaviour and mortality of generations yet to come. This paper investigates, by major world regions and countries, what we know about population growth, what can be projected with reasonable certainty, and what is pure speculation. The exposition sets a frame for analysing demographic driving forces that are expected to increase human demand and pressures on land and water resources. These have been contrasted with current resource assessments of regional availability and use of land, in particular with estimates of remaining land with cultivation potential. In establishing a balance between availabilty of land resources and projected needs, the paper distinguishes regions with limited land and water resources and high population pressure from areas with abundant resources and low or moderate demographic demand. Overall, it is estimated that two–thirds of the remaining balance of land with rainfed cultivation potential is currently covered by various forest ecosystems and wetlands. The respective percentages by region vary between 23% in Southern Africa to 89% in South–Eastern Asia. For Latin America and Asia the estimated share of the balance of land with cultivation potential under forest and wetland ecosystems is about 70%, in Africa this is about 60%. If these were to be preserved, the remaining balance of land with some potential for rainfed crop cultivation would amount to some 550 million hectares. The regions which will experience the largest difficulties in meeting future demand for land resources and water, or alternatively have to cope with much increased dependency on external supplies, include foremost Western Asia, South–Central Asia, and Northern Africa. A large stress on resources is to be expected also in many countries of Eastern, Western and Southern Africa.
Adapting and improving crops: the endless task
Authors: Evans L. T.
Published: October 2002

The Malthusian prognosis has been undermined by an exponential increase in world food supply since 1960, even in the absence of any extension of the arable area. The requisite increases in yield of the cereal staples have come partly from agronomic intensification, especially of nitrogenous fertilizer use made possible by the dwarfing of wheat and rice, in turn made feasible by herbicide development. Cereal dwarfing also contributed to a marked rise in harvest index and yield potential.

Although there is still scope for some further improvement in harvest index and environmental adaptation, it is not apparent how a doubling of yield potential can be achieved unless crop photosynthesis can be substantially enhanced by genetic engineering. Empirical selection for yield has not enhanced photosynthetic capacity to date, but nitrogenous and other fertilizers have done so, and there is still scope for agronomic increases in yield and for new synergisms between agronomy and plant breeding.
The environmental implications of intensified land use in developing countries
Authors: Tinker P. B.
Published: October 2002

The major agricultural intensifications in the developed world over the last half century have produced a range of important environmental problems. These include pollution, damage to wildlife and landscape and other issues, both on- and off-site. These are largely being controlled by scientific investigation and Government regulation. As developing countries increase agricultural production over the next 30 years, this may also cause even more serious environmental damage.

The paper distinguishes between production-related on-site damage, and off-site and more extensive effects. Both may involve soil and water effects, such as soil erosion, salinization, siltation, eutrophication and loss of water quality. The use of more agrochemicals can damage water quality, health, wildlife and biodiversity. Loss of habitat from the extension of farming is particularly damaging to biodiversity. A developing off-site problem is the production of greenhouse gases by farming systems, including the conversion of forests to farmland. In the future the introduction of genetically engineered species of plants, animals or microbes will need secure control.

Work, probably on a catchment basis, is necessary to understand and control these problems. The three main requirements are much better environmental information from the developing world; the selection of environmental indicators to be monitored; and the support of local farmers in protecting the environment. There are encouraging indications of farmer concern and action over obvious on-site damage, but this may not extend to extensive off-site issues. The main danger is that developing food scarcity would cause the environmental issues to be ignored in a race for production.
Genetic information and insurance: some ethical issues
Authors: O'neill Onora
Published: October 2002

Life is risky, and insurance provides one of the best developed ways of controlling risks. By pooling, and so transferring risks, those who turn out to suffer antecedently uncertain harms can be assured in advance that they will be helped if those harms arise; they can then plan their lives and activities with confidence that they are less at the mercy of ill fortune.

Both publicly organized and commercial insurance can organize the pooling of risk in ways that are beneficial for all concerned. They provide standard ways of securing fundamental ethical values such as solidarity and mutuality. Although policy holders do not know or contract with one another, each benefits from the contribution of others to a shared scheme for pooling and so controlling risk. Although there is a limit to the degree to which commercially–based insurance, where premiums depend on risk level, can go beyond mutuality towards solidarity, in practice it too often achieves a measure of solidarity by taking a broad brush approach to pooling risk

However, the ordinary practices of insurance, and in particular of commercial insurance, also raise ethical questions. These may be put in simple terms by contrasting the way in which an insurance market discriminates between different people, on the basis of characteristics that (supposedly) determine their risk level, and our frequent abhorrence of discrimination, in particular on the basis on religious, racial and gender grounds. Are the discriminations on which insurance practice relies upon as standard acceptable or not?

The increasing availability of genetic information, which testing (of individuals) and screening (of populations) may provide, could lend urgency to these questions. Genetic information may provide a way of obtaining more accurate assessment of individual risks to health and life. This information could be used to discriminate more finely between the risk levels of different individuals, and then to alter the availability and the costs of health, life and unemployment insurance to them. Since all of these forms of insurance bear very directly on the way most people live, it will matter to them how (if at all) insurers take account of genetic information. Will use of this information improve or damage the capacity of insurance to provide confidence in the face of uncertain harms, and help if they happen? Will it discriminate in acceptable or in unacceptable ways? Will it support or damage the sorts of mutuality and solidarity various sorts of insurance schemes have successfully institutionalized?
The likely financial effects on individuals, industry and commerce of the use of genetic information
Authors: Ross Tom
Published: October 2002

In this paper I look at the financial implications of genetic testing, particularly in the employment and pensions fields. I have generally not covered life insurance, as that is covered in other papers in this Discussion Meeting. However, the issues are similar, although the emphasis is different. Inevitably there is an element of speculation involved; genetic testing is in its infancy and so we cannot predict either what information we will be able to obtain through genetic testing, nor the uses that may be devised for this information.
The forms of knowledge mobilized in some machine vision systems
Authors: Brady Michael
Published: October 2002

This paper describes a number of computer vision systems that we hae constructed, and which are firmly based on knowledge of diverse sorts. However, that knowledge is often represented in a way that is only accessible to a limited set of processes, that make limited use of it, and though the knowledge is amenable to change, in practice it can only be changed in rather simple ways. The rest of the paper addresses the questions: (i) what knowledge is mobilized in the furtherance of a perceptual task? (ii) how is that knowledge represented? and (iii) how is that knowledge mobilized? First we review some cases of early visual processing where the mobilization of knowledge seems to be a key contributor to success yet where the knowledge is deliberately represented in a quite inflexible way. After considering the knowledge that is involved in overcoming the projective nature of images, we move the discussion to the knowledge that was required in programs to match, register, and recognize shapes in a range of applications. Finally, we discuss the current state of process architectures for knowledge mobilization.