bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of Total Loss Factor Measurements for the Determination of Sound Insulation
Authors: Meier A. , Schmitz A. 
Published: October 2002

The influence of the total loss factor of building elements on their sound insulation is well known, although the problem of measuring this value was up to now not solved completely. This article describes an improved measuring method for total loss factors of building products especially for heavy elements. Furthermore, the principle of conversion of different results for transmission loss of the same type of wall under different mounting conditions using the total loss factor is presented. Measurement results in a transmission suite were examined and corrected with values derived from the improved measuring method.
Inter-Laboratory Test of Sound Insulation Measurements on Heavy Walls: Part I — Preliminary Test
Authors: Schmitz A. , Meier A. , Raabe G. 
Published: October 2002

The intention of sound reduction index (SRI) measurements in transmission suites is to obtain more reliable values of the specific test element's sound insulation properties. Unfortunately, these values are influenced by the mounting of the test element itself and the construction design of the test facility. Both the mounting of the test element and, in part, the design of the test facility can effect the damping of the test element. From previous studies a suggested solution has been to take into account the damping in terms of the test element's loss factor. By incorporation of the loss factor in SRI measurements, of heavy walls, it has been suggested that this could reduce the deviations in SRI values due to laboratory influences. To determine the variance of sound transmission measurements in test facilities for a heavy wall, an inter-laboratory test (ILT) was performed in twelve different institutes. This ILT study included the measurement of sound reduction index, velocity levels and damping. In this first part, of a two part paper, a review concerning the principle previous studies is given. Furthermore, decisions regarding the choice of the test element, principal measurements and participating laboratories are reported.
Softening of Normal Strength and High-Strength Concrete Frames
Authors: Mendis Priyan 
Published: October 2002

In the 21st century, computing facilities will make it possible to opt on a regular basis for more accurate rigorous methods of analysis. A rigorous collapse load analysis requires a knowledge of the behaviour of plastic hinges up to advanced curvatures. Concrete sections characteristically soften, that is the bending moment capacity decreases with increasing curvatures after the end of the plastic plateau while steel sections undergo a hardening phase. Consideration of softening is essential in a rational analysis. In this paper, the important aspects of softening of concrete frame structures are reviewed. High-strength concrete (f'c>50 MPa) is a more brittle construction material than normal strength concrete. High-strength concrete sections show a steeper softening slope when compared with similar normal strength concrete sections. An example is presented to demonstrate that a HSC frame structure with steeper softening slopes will have a lower collapse load.
Inelastic Dynamic Response of RC Bridges Subjected to Spatial Non-Synchronous Earthquake Motion
Authors: Tzanetos N. , Elnashai A.S. , Hamdan F.H. , Antoniou S. 
Published: October 2002

The assumption that earthquake response of extended structures, of which bridges is one example, may be studied ignoring the possibility of out-of-synch motion of various supports is examined in this paper. The purpose is to assess whether the reduction of dynamic response is sufficient to offset the increase in relative displacements, due to independent motion of different supports. The paper starts with a review of possible damage patterns due to asynchronous motion. Thereafter, a brief literature review is undertaken, followed by an assessment of the status of seismic design codes concerning this issue. Advanced inelastic analysis, using sophisticated material models and analysis techniques, is then employed to explore characteristics of input motion and structural configuration, which may lead to unconservative results from conventional (synchronous) analysis. Natural and artificial earthquake records are applied, representing travelling wave as well as geometric incoherence effects. Two model structures of medium span RC bridges are studied, subjected to different boundary conditions that influence the mode contributions. This is undertaken under transverse, longitudinal and vertical earthquake motion. The large volume of results, represented as displacement and force time-histories as well as Fourier amplitude spectra of the acceleration response, are distilled and used to assess the balance between dynamic de-tuning and static relative displacements. It is concluded that the conventional synchronous case provides conservative results for vertical vibrations. However, unconservative results, of up to 30%, are obtained for transverse and longitudinal response of short periods of structural vibrations, as well as cases where the higher modes of response are likely to be excited.
A comparison of fertility control and lethal control of bovine tuberculosis in badgers: the impact of perturbation induced transmission
Authors: Swinton J. , Tuyttens F. , Macdonald D. , Nokes D. J. , Cheeseman C. L. , Clifton-hadley R. 
Published: October 2002

In this paper we use mathematical modelling to consider the broad advantages and disadvantages of fertility control over lethal control for bovine tuberculosis in badger populations.

We use a deliberately simple model, attempting to capture only the key transmission processes. The model is parametrized with reference to the long–term Woodchester Park study. Estimates of mortality rate from this study suggest no significant extra mortality risk for animals with evidence of infection as indicated by the presence of anti-
Mycobacterium bovis
antibodies or
M. bovis
isolation.

We find that large reductions in prevalence are sometimes the consequence of only moderate reductions in population numbers. If we assume that the act of control does not in itself affect transmission rates, then as far as eradication is concerned, both fertility control and mortality control operate through the same epidemiological mechanism, the removal of susceptibles: if one is in principle capable of keeping a population low enough to be infection free then so is the other. It is necessary to continue either form of control at regular intervals to maintain a constant level of infection in the long term. If control were to be stopped, return to precontrol levels of badger population and infection prevalence would be expected within a few years. Fertility control is less effective in reducing population density than lethal control since it can only act, at maximum, to remove one age cohort per year. It is also less effective in reducing transmission as it can only ever remove susceptibles, while lethal control also removes infectious badgers.
However, if the social disturbance caused by lethal control does in fact increase contact rates for the remaining infectious badgers, the relative efficacies of the two strategies become a great deal less clear. While we have no quantitative data on the extent to which social perturbation does act to promote transmission, model simulations show that it is possible to develop plausible scenarios in which the lethal control may actually act to increase the absolute numbers of animals infected, while reducing the number of uninfected animals to very low numbers.
The economic determinants of land degradation in developing countries
Authors: Barbier Edward B. 
Published: October 2002

The following paper investigates the economic determinants of land degradation in developing countries. The main trends examined are rural household's decisions to degrade as opposed to conserve land resources, and the expansion of frontier agricultural activity that contributes to forest and marginal land conversion. These two phenomena appear often to be linked. In many developing areas, a poor rural household's decision whether to undertake long–term investment in improving existing agricultural land must be weighed against the decision to abandon this land and migrate to environmentally fragile areas. Economic factors play a critical role in determining these relationships. Poverty, imperfect capital markets and insecure land tenure may reinforce the tendency towards short–term time horizons in production decisions, and may bias land use decisions against long–term land management strategies. In periods of commodity booms and land speculation, wealthier households generally take advantage of their superior political and market power to ensure initial access to better quality resources, in order to capture a larger share of the resource rents. Poorer households are confined either to marginal environmental areas where resource rents are limited, or only have access to resources once they are degraded and rents dissipated.Overall trends in land degradation and deforestation are examined, followed by an overview of rural household's resource management decisions with respect to land management, frontier agricultural expansion, and migration from existing agricultural land to frontiers. Finally, the discussion focuses on the scope for policy improvements to reduce economic constraints to effective land management.
Variable place–cell coupling to a continuously viewed stimulus: evidence that the hippocampus is part of a perceptual system
Authors: Rotenberg Alexander , Muller Robert U. 
Published: October 2002

A key feature of perception is that the interpretation of a single, continuously available stimulus can change from time to time. This aspect of perception is well illustrated by the use of ambiguous figures that can be seen in two different ways. When people view such a stimulus they almost universally describe what they are seeing as jumping between two states. If it is agreed that this perceptual phenemonon is causally linked to the activity of nerve cells, the state jumps would have to occur in conjunction with changes in neural activity somewhere in the nervous system.The experiments described in this paper suggest that hippocampal place cells are part of a perceptual system. Variations were made of a ‘cue–card rotation’ experiment on rats in which the angular position of a prominent visual stimulus on the wall of cylinder is changed in the rat's presence. The three main results are as follows. (i) Place–cell firing fields remain stationary if the cue is rotated by 180° so that the relation between the cue and the field is altered. (ii) Firing fields rotate by 45° when the cue is rotated by 45°and the relation between the field and the card is maintained. (iii) If the cue is first rotated by 180°and then rotated in a series of 45° steps, the field finishes at a different angular position relative to the card when the card is back in its original position. Thus, place cells can fire in two different ways in reponse to a continuously viewed stimulus. It is concluded that place cells reveal that the hippocampal mapping system also has properties expected of a perceptual system.
Long live the Queen's subjects
Authors: Perutz M. F. 
Published: October 2002

In 1952, the Queen congratulated 255 people on their hundredth birthdays and 1135 couples on their sixtieth wedding anniversaries. By 1996, these numbers had risen to 5218 and 11 688, respectively. Semilogarithmic plots, normalized to constant numbers of births and marriages, show steady exponential rises in the number of centenarians with a doubling time of 11 years, and of diamond weddings with a doubling time of 19 years. An alternative plot of the numbers of those reaching a hundred between 1910 and 1990, based on registers of births and deaths and normalized to constant births, shows an annual rise of only 1% from 1910 to 1946, followed by a steady exponential rise with a doubling time of 12 years, closely matching that of 11 years derived from the Queen's figures.
The exponential rise in the number of those born from 1846 onwards living to a hundred precedes by many years the general rise in the expectation of life at birth and the general drop in mortality from infectious diseases, but it coincides with the beginning of a steady rise in real wages. Another important factor may be improved medical treatment at old age from 1946 onwards.
A Thapsigargin-Sensitive Ca2+ Pump Is Present in the Pea Golgi Apparatus Membrane
Authors: Ordenes Viviana R. , Reyes Francisca C. , Wolff Daniel , Orellana Ariel 
Published: October 2002

Abstract
The Golgi apparatus behaves as a bona fide Ca2+ store in animal cells and yeast (Saccharomyces cerevisiae); however, it is not known whether this organelle plays a similar role in plant cells. In this work, we investigated the presence of an active Ca2+accumulation mechanism in the plant cell Golgi apparatus. Toward this end, we measured Ca2+ uptake in subcellular fractions isolated from the elongating zone of etiolated pea (Pisum sativum) epicotyls. Separation of organelles using sucrose gradients showed a strong correlation between the distribution of an ATP-dependent Ca2+ uptake activity and the Golgi apparatus marker enzyme, xyloglucan-fucosyltransferase. The kinetic parameters obtained for this activity were: the rate of maximum Ca2+ uptake of 2.5 nmol mg min−1 and an apparent K m for Ca2+ of 209 nm. The ATP-dependent Ca2+ uptake was strongly inhibited by vanadate (inhibitor concentration causing 50% inhibition [I50] = 126 μm) and cyclopiazonic acid (I50 = 0.36 nmol mg protein−1) and was not stimulated by calmodulin (1 μm). Addition of Cd2+ and Cu2+ at nanomolar concentration inhibited the Ca2+ uptake, whereas Mn2+, Fe2+, and Co2+ had no significant effect. Interestingly, the active calcium uptake was inhibited by thapsigargin (apparent I50 = 88 nm), a well-known inhibitor of the endoplasmic reticulum and Golgi sarco-endoplasmic reticulum Ca2+ ATPase from mammalian cells. A thapsigargin-sensitive Ca2+ uptake activity was also detected in a cauliflower (Brassica oleracea) Golgi-enriched fraction, suggesting that other plants may also possess thapsigargin-sensitive Golgi Ca2+ pumps. To our knowledge, this is the first report of a plant Ca2+pump activity that shows sensitivity to low concentrations of thapsigargin.
Sensitivity of Photosynthesis in a C4 Plant, Maize, to Heat Stress
Authors: Crafts-Brandner Steven J. , Salvucci Michael E. 
Published: October 2002

Abstract
Our objective was to determine the sensitivity of components of the photosynthetic apparatus of maize (Zea mays), a C4 plant, to high temperature stress. Net photosynthesis (Pn) was inhibited at leaf temperatures above 38°C, and the inhibition was much more severe when the temperature was increased rapidly rather than gradually. Transpiration rate increased progressively with leaf temperature, indicating that inhibition was not associated with stomatal closure. Nonphotochemical fluorescence quenching (qN) increased at leaf temperatures above 30°C, indicating increased thylakoid energization even at temperatures that did not inhibit Pn. Compared with CO2 assimilation, the maximum quantum yield of photosystem II (F v/F m) was relatively insensitive to leaf temperatures up to 45°C. The activation state of phosphoenolpyruvate carboxylase decreased marginally at leaf temperatures above 40°C, and the activity of pyruvate phosphate dikinase was insensitive to temperature up to 45°C. The activation state of Rubisco decreased at temperatures exceeding 32.5°C, with nearly complete inactivation at 45°C. Levels of 3-phosphoglyceric acid and ribulose-1,5-bisphosphate decreased and increased, respectively, as leaf temperature increased, consistent with the decrease in Rubisco activation. When leaf temperature was increased gradually, Rubisco activation acclimated in a similar manner as Pn, and acclimation was associated with the expression of a new activase polypeptide. Rates of Pn calculated solely from the kinetics of Rubisco were remarkably similar to measured rates if the calculation included adjustment for temperature effects on Rubisco activation. We conclude that inactivation of Rubisco was the primary constraint on the rate of Pn of maize leaves as leaf temperature increased above 30°C.
In Vivo and in Vitro Phosphorylation of Membrane and Soluble Forms of Soybean Nodule Sucrose Synthase
Authors: Komina Olga , Zhou You , Sarath Gautam , Chollet Raymond 
Published: October 2002

Abstract
Sucrose synthase (SS) is a known phosphoserine (SerP)-containing enzyme in a variety of plant “sink” organs, including legume root nodules, where it is phosphorylated primarily at Ser-11. Using immunofluorescence confocal microscopy, we documented that part of the total SS (nodulin-100) pool in mature soybean (Glycine max) nodules is apparently associated with the plasma membrane in situ, and we report that this association is very “tight,” as evidenced by a variety of chemical and enzymatic pretreatments of the isolated microsomal fraction. To investigate the in situ and in planta phosphorylation state of the membrane (m) and soluble (s) forms of nodule SS, three complementary approaches were used. First, excised nodules were radiolabeled in situ with [32P]Pi for subsequent analysis of phosphorylated m- and s-SS; second, immunopurified s- and m-SS were used as substrate in “on-bead” assays of phosphorylation by nodule Ca2+-dependent protein kinase; and third, SS-Ser-11(P) phosphopeptide-specific antibodies were developed and used. The collective results provide convincing evidence that microsomal nodulin-100 is phosphorylated in mature nodules, and that it is hypophosphorylated relative to s-SS (on an equivalent SS protein basis) in attached, unstressed nodules. Moreover, the immunological data and related phosphopeptide mapping analyses indicate that a homologous N-terminal seryl-phosphorylation domain and site reside in microsomal nodulin-100. We also observed that mild, short-term inorganic nitrogen and salt stresses have a significant negative impact on the content and N-terminal phosphorylation state of nodule m- and s-SS, with the former being the more sensitive of the two SS forms.
Redox Regulation of Arabidopsis 3-Deoxy-d-arabino-Heptulosonate 7-Phosphate Synthase
Authors: Entus Robert , Poling Michael , Herrmann Klaus M. 
Published: October 2002

Abstract
The cDNA for 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase of Arabidopsis encodes a polypeptide with an amino-terminal signal sequence for plastid import. A cDNA fragment encoding the processed form of the enzyme was expressed in Escherichia coli. The resulting protein was purified to electrophoretic homogeneity. The enzyme requires Mn2+ and reduced thioredoxin (TRX) for activity. Spinach (Spinacia oleracea) TRX f has an apparent dissociation constant for the enzyme of about 0.2 μm. The corresponding constant for TRX m is orders of magnitude higher. In the absence of TRX, dithiothreitol partially activates the enzyme. Upon alkylation of the enzyme with iodoacetamide, the dependence on a reducing agent is lost. These results indicate that the first enzyme in the shikimate pathway of Arabidopsis appears to be regulated by the ferredoxin/TRX redox control of the chloroplast.
The out of phase 1 Mutant Defines a Role for PHYB in Circadian Phase Control in Arabidopsis
Authors: Salomé Patrice A. , Michael Todd P. , Kearns Ellen V. , Fett-Neto Arthur G. , Sharrock Robert A. , McClung C. Robertson 
Published: October 2002

Abstract
Arabidopsis displays circadian rhythms in stomatal aperture, stomatal conductance, and CO2 assimilation, each of which peaks around the middle of the day. The rhythmic opening and closing of stomata confers a rhythm in sensitivity and resistance, respectively, to the toxic gas sulfur dioxide. Using this physiological assay as a basis for a mutant screen, we isolated mutants with defects in circadian timing. Here, we characterize one mutant, out of phase 1 (oop1), with the circadian phenotype of altered phase. That is, the timing of the peak (acrophase) of multiple circadian rhythms (leaf movement, CO2 assimilation, andLIGHT-HARVESTING CHLOROPHYLL a/b-BINDING PROTEINtranscription) is early with respect to wild type, although all circadian rhythms retain normal period length. This is the first such mutant to be characterized in Arabidopsis. oop1 also displays a strong photoperception defect in red light characteristic ofphytochrome B (phyB) mutants. Theoop1 mutation is a nonsense mutation ofPHYB that results in a truncated protein of 904 amino acids. The defect in circadian phasing is seen in seedlings entrained by a light-dark cycle but not in seedlings entrained by a temperature cycle. Thus, PHYB contributes light information critical for proper determination of circadian phase.
Seasonal Changes of Plasma Membrane H+-ATPase and Endogenous Ion Current during Cambial Growth in Poplar Plants
Authors: Arend Matthias , Weisenseel Manfred H. , Brummer Maria , Osswald Wolfgang , Fromm Jörg H. 
Published: October 2002

Abstract
The plasma membrane H+-ATPase (PM H+-ATPase), potassium ions, and endogenous ion currents might play a fundamental role in the physiology of cambial growth. Seasonal changes of these parameters were studied in twigs ofPopulus nigra and Populus trichocarpa. Monoclonal and polyclonal antibodies against the PM H+-ATPase, x-ray analysis for K+ localization and a vibrating electrode for measurement of endogenous ion currents were used as probes. In dormant plants during autumn and winter, only a slight immunoreactivity against the PM H+-ATPase was found in cross sections and tissue homogenates, K+ was distributed evenly, and the density of endogenous current was low. In spring during cambial growth, strong immunoreactivity against a PM H+-ATPase was observed in cambial cells and expanding xylem cells using the monoclonal antibody 46 E5 B11 F6 for fluorescence microscopy and transmission electron microscopy. At the same time, K+ accumulated in cells of the cambial region, and strong endogenous current was measured in the cambial and immature xylem zone. Addition of auxin to dormant twigs induced the formation of this PM H+-ATPase in the dormant cambial region within a few days and an increase in density of endogenous current in shoot cuttings within a few hours. The increase in PM H+-ATPase abundance and in current density by auxin indicates that auxin mediates a rise in number and activity of an H+-ATPase in the plasma membrane of cambial cells and their derivatives. This PM H+-ATPase generates the necessary H+-gradient (proton-motive force) for the uptake of K+ and nutrients into cambial and expanding xylem cells.