bluuebunny/crossref_metadata_2025 huggingface dataset:
Housing Markets, Government Behaviors, and Housing Choice: A Case Study of Three Cities in China
Authors: Huang Youqin
Published: December 2004

Housing reform in urban China has introduced market mechanisms into a previously welfare-oriented housing system. Although microlevel factors such as household characteristics begin to shape housing behavior in urban China as is the case in the West, macrolevel constraints and opportunities defined by not only housing stocks and housing markets but also local government behaviors continue to be crucial. By studying housing choice in Beijing, Chongqing, and Jiangyin, I find that local governments in different cities behave differently in reforming the housing system, which in turn create different housing stocks and housing markets and thus lead to different patterns of housing behavior. A housing stock dominated by public housing, a tight housing market, and a conservative local government all encourage households to choose public housing and rental, as is the case in Beijing, while a diverse housing stock with affordable housing prices, and an aggressive local government often encourage households to choose private housing and homeownership, indicated by the case of Jiangyin.
Intraurban Residential Relocation in Shanghai: Modes and Stratification
Authors: Wu Fulong
Published: December 2004

Housing marketisation provides an opportunity for households to choose their residences. However, not all households benefit equally from residential relocation. This paper uses a recent residential survey in Shanghai to examine different relocation modes and their implications for housing consumption. The findings suggest that better education, absence of work-unit affiliation, higher expectation for housing consumption, and the move from the outer to inner areas are more likely to be associated with active relocation through commodity housing purchase. Residential relocation in urban China has a stronger association with the household's position within the spectrum from state redistribution to market reward than with life cycles and consequent adjustment of housing demand which are the primary reasons for residential mobility in a mature market. Household income, the educational level, and previous housing space are determinants of changing housing consumption. Intraurban residential relocation gives a higher return to those who are better educated and who have been already in possession of larger living space, and to the move from outer to inner areas. Active relocation and workplace-housing allocation generate higher space returns to households than do other modes of relocation. Whereas pragmatic concerns for social stability plus strong tenancy rights help inner-city households gain compensation in residential relocation, urban redevelopment generates the lowest space return. Residential displacement is now becoming a contentious issue. As such, residential relocation is a process that differentiates urban space under market transition.
Housing Preferences in a Transitional Housing System: The Case of Beijing, China
Authors: Wang Donggen , Li Si-Ming
Published: December 2004

For a prolonged period of time, the Chinese state had monopolised housing provision. Chinese people had virtually no choice of housing. Much has changed with the deepening of the market-oriented reform launched since 1979. A housing market, though not yet a full-fledged one, has been established. People now have greater freedom to choose their homes. More and more people buy houses from the market. There is, therefore, an urgent need for an inquiry into how housing decisions in China are made, what people's preferences for housing are, and what factors influence their housing choices. To this end, the authors study the joint choice of dwelling and neighbourhood by potential homebuyers in Beijing. Because the housing market in China is still in an embryonic state and highly regulated by the government, one may not be able to get information on actual housing choices to reveal housing preferences. This study thus adopts the stated preference modelling approach. Data were collected in 2001 in Beijing, capital of China. The study shows that, in general, neighbourhood variables are more important than dwelling variables in the choice of housing in Beijing. Associated with this is the importance attached to districts with a good reputation and the concern for dwelling and neighbourhood security.
Local Governance and Environmental Conservation: Gravel Politics and the Preservation of an Endangered Bird Species in Taiwan
Authors: Tang Shui-Yan , Tang Ching-Ping
Published: December 2004

Despite its many promises, devolved governance may pose great challenges to environmental conservation, especially in the context of newly democratized polities where local communities tend to be dominated by place-bound clientele networks that pursue developmental interests at the expense of conservation. In this paper the authors examine how a conservation movement in Huben Village of Yunlin County in Taiwan has successfully been organized to save the endangered bird species Fairy Pitta ( Pitta nuymphia) against gravel extraction activities that were backed by local clientele networks of politicians and business interests. The case illustrates how challenges of devolved governance can be addressed not necessarily by centralized authority but by connecting grassroots victims of environmental degradation with broader conservation movements supported by networks of civic organizations that transcend narrow geographical interests.
Physiological and morphological responses to water stress in Aegilops biuncialis and Triticum aestivum genotypes with differing tolerance to drought
Authors: Molnár István , Gáspár László , Sárvári Éva , Dulai Sándor , Hoffmann Borbála , Molnár-Láng Márta , Galiba Gábor
Published: December 2004

The physiological and morphological responses to water stress induced by polyethylene glycol (PEG) or by withholding water were investigated in Aegilops biuncialis Vis. genotypes differing in the annual rainfall of their habitat (1050, 550 and 225 mm year–1) and in Triticum aestivum L. wheat genotypes differing in drought tolerance. A decrease in the osmotic pressure of the nutrient solution from –0.027 to –1.8 MPa resulted in significant water loss, a low degree of stomatal closure and a decrease in the intercellular CO2 concentration (Ci) in Aegilops genotypes originating from dry habitats, while in wheat genotypes high osmotic stress increased stomatal closure, resulting in a low level of water loss and high Ci. Nevertheless, under saturating light at normal atmospheric CO2 levels, the rate of CO2 assimilation was higher for the Aegilops accessions, under high osmotic stress, than for the wheat genotypes. Moreover, in the wheat genotypes CO2 assimilation exhibited less or no O2 sensitivity. These physiological responses were manifested in changes in the growth rate and biomass production, since Aegilops (Ae550, Ae225) genotypes retained a higher growth rate (especially in the roots), biomass production and yield formation after drought stress than wheat. These results indicate that Aegilops genotypes, originating from a dry habitat have better drought tolerance than wheat, making them good candidates for improving the drought tolerance of wheat through intergeneric crossing.
Greenhouse and field cucumber genotypes use different mechanisms to protect against dark chilling
Authors: Zhou Yan-Hong , Huang Li-Feng , Du Yao-Shun , Yu Jing-Quan
Published: December 2004

Diurnal changes in photosynthetic gas exchange and chlorophyll fluorescence were measured after two consecutive night chills to reveal the photosynthetic characteristics and the mechanism of photoprotection in a greenhouse genotype Jinyou No. 3 (GH), and in a field genotype Jinyan No. 4 (OF) of cucumber (Cucumis sativus L.). Both genotypes showed inhibition of CO2 assimilation immediately after the dark chill, with OF exhibiting a greater reduction. Dark chilling had little effect on stomatal limitation (l) and RuBP regeneration (Jmax) but significantly decreased maximum carboxylation velocity of Rubisco (Vcmax). The reduced capacity for CO2 fixation in the Calvin cycle induced a downstream regulation of PSII photochemistry, a mechanism that regulates the photosynthetic electron transport to match the lower demand for ATP and NADPH in the stroma of chloroplasts. The reduced quantum efficiency of PSII photochemistry was mainly due to reductions both in the photochemical quenching coefficient (qP) and in the efficiency of excitation energy capture by open PSII reaction centres (Fv′ / Fm′) for OF, but only to the latter for GH. Night chills resulted in an enhanced photorespiration proportion in GH and an O2-dependent alternative electron flux in OF, which served as protective mechanisms for the two varieties. These results showed that there are genotypic differences in the limitation factor for CO2 assimilation and in photo-protection mechanism to night chill in cucumber.
What determines rates of photosynthesis per unit nitrogen in Eucalyptus seedlings?
Authors: Warren Charles R. , Adams Mark A.
Published: December 2004

Species originating from xeric sites are characterised by slower rates of photosynthesis per unit nitrogen (PNUE) than species from mesic sites, but we lack mechanistic explanations for these interspecific differences. We examined N allocation to Rubisco and chlorophyll, and photosynthetic characteristics in seedlings of nine Eucalyptus species grown in a fully sunlit glasshouse with an optimal supply of nutrients. Species were selected from mesic (1800 mm year–1 rainfall) through to semi-arid habitats (300 mm year–1). All species were characterised by allocation of a large proportion of N to Rubisco (32–48%) with high in vivo specific activity. Intercellular CO2 concentration (Ci) varied between 260 and 300 μmol mol–1, and thus, stomatal limitations were low in all species. This combination of traits resulted in a PNUE (172–335 μmol mol–1 s–1) that was higher than is commonly observed in tree species and which may be related to the rapid growth, water-spender strategy of Eucalyptus seedlings. There were significant differences in photosynthetic parameters and N allocation among species, but these were only weakly related to rainfall at the site of seed origin. There were correlations of Ci with PNUE but a sensitivity analysis suggested that interspecific variation in Ci explained at most 7% of variation in PNUE. Photosynthesis and PNUE were also rather insensitive to large interspecific differences in RuBP-limited rate of electron transport per unit N (Jmax / N), because photosynthesis was primarily limited by the maximum rate of carboxylation (Vcmax). PNUE was most sensitive to changes in N allocation to Rubisco and Vcmax / Rubisco.
Bcl-2-mediated alterations in endoplasmic reticulum Ca
2+
analyzed with an improved genetically encoded fluorescent sensor
Authors: Palmer Amy E. , Jin Can , Reed John C. , Tsien Roger Y.
Published: December 2004

The endoplasmic reticulum (ER) serves as a cellular storehouse for Ca
2+
, and Ca
2+
released from the ER plays a role in a host of critical signaling reactions, including exocytosis, contraction, metabolism, regulation of transcription, fertilization, and apoptosis. Given the central role played by the ER, our understanding of these signaling processes could be greatly enhanced by the ability to image [Ca
2+
]
ER
directly in individual cells. We created a genetically encoded Ca
2+
indicator by redesigning the binding interface of calmodulin and a calmodulin-binding peptide. The sensor has improved reaction kinetics and a
K
d
ideal for imaging Ca
2+
in the ER and is no longer perturbed by large excesses of native calmodulin. Importantly, it provides a significant improvement over all previous methods for monitoring [Ca
2+
]
ER
and has been used to directly show that, in MCF-7 breast cancer cells, the antiapoptotic protein B cell lymphoma 2 (Bcl-2) (
i
) lowers [Ca
2+
]
ER
by increasing Ca
2+
leakage under resting conditions and (
ii
) alters Ca
2+
oscillations induced by ATP, and that acute inhibition of Bcl-2 by the green tea compound epigallocatechin gallate results in an increase in [Ca
2+
]
ER
due to inhibition of Bcl-2-mediated Ca
2+
leakage.
Delivering Public Health Care Services: Substitutes, Complements, or Both?
Authors: Rask Kimberly J. , Rask Kevin N.
Published: December 2004

In this article we investigate how the availability of public health care providers increases (complement) or decreases (substitute) the likelihood of having public or private health insurance. The probability of each of three insurance alternatives (uninsured, Medicaid, private insurance) is modeled as a function of the availability of public programs in the respondents’community along with individual characteristics including family income, health status, and family structure. Using population‐based estimates, public hospitals are associated with a crowd‐out rate of 3.5 percent to 8.6 percent. Federally qualified health centers were associated with a net complementary effect (additional public insurance take‐up) of 7.1 percent. (JEL I11, I18, I38)
Empirical Analysis of Entry in the Local Exchange Market: The Case of Pacific Bell*
Authors: Roycroft Trevor R.
Published: December 2004

This article examines local exchange entry in SBC's California territory. Analysis is conducted based on five‐digit zip code areas. Information on economic, demographic, and regulatory variables, including prices of unbundled loops, is included in the analysis. Results of censored Poisson analysis indicate that these economic, demographic, and regulatory variables play a statistically significant role in leading to higher probabilities of low levels of entry in areas where loop prices are higher, fewer large businesses exist, and costs of self‐provision are higher. (JEL L51, L96)
Knowledge Spillovers and High‐technology Clustering: Evidence from Taiwan's Hsinchu Science‐Based Industrial Park
Authors: Tsai Diana H. A.
Published: December 2004

Knowledge spillovers of high‐technology industries are alleged to be important determinants of industrial clustering. Dynamic production modeling is applied to measure the sectoral and spatial spillover effects to study the implications of various types of knowledge spillovers on high‐technology industry clustering in Taiwan's Hsinchu Science‐based Industrial Park (HSIP). The analysis is performed using the Taiwanese government's industrial census of technological activities at the micro level with 2340 plants for the period 1986–1995. We find substantive sectoral and spatial knowledge spillover effects, which are considered to be major motivating forces for regional concentration patterns of Taiwan's high‐technology industries. (JEL L10, O30)
Double–diffusive convection in a porous medium with a concentration based internal heat source
Authors: Hill Antony A.
Published: December 2004

Linear and nonlinear stability analyses of double–diffusive convection in a fluid–saturated porous layer with a concentration based internal heat source are studied. Darcy's law and the Boussinesq approximation are employed, with the equation of state taken to be linear with respect to temperature and concentration. Both the numerical and analytical analysis for the linear theory strongly suggest the presence of a critical value
γ
c
, where
γ
is essentially a measure of the internal heat source, for which no oscillatory convection occurs when
γ
c
⩽
γ
. This, in the present literature, appears to be an unobserved phenomenon.

A nonlinear energy stability analysis demonstrates more comparable linear and nonlinear thresholds when the linear theory predicts the onset of fully stationary convection. However, irrespective of the
γ
value, the agreement of the thresholds does deteriorate as the solute Rayleigh number
R
c
increases.
A rational model for the turbulent scalar fluxes
Authors: Younis Bassam A. , Speziale Charles G. , Clark Timothy T.
Published: December 2004

The paper reports on an alternative approach to modelling the turbulent scalar fluxes that arise from time averaging the transport equation for a scalar. In this approach, a functional relationship between these fluxes and various tensor quantities is constructed with guidance from the exact equations governing the transport of fluxes. Results from tensor representation theory are then used to obtain an explicit relationship between the fluxes and the terms in the assumed functional relationship. Where turbulence length– and time–scales are implied, these are determined from two scalar quantities: the turbulence kinetic energy and its rate of dissipation by viscous action. The general representation is then reduced by certain justifiable assumptions to yield a practical model for the turbulent scalar fluxes that is explicit and algebraic in these quantities and one that correctly reflects their dependence on the gradients of mean velocity and on the details of the turbulence. Examination of alternative algebraic models shows most to be subsets of the present proposal. The new model is calibrated using results from large–eddy simulations (LESs) of homogeneous turbulence with passive scalars and then assessed by reference to benchmark data from heated turbulent shear flows. The results obtained show the model to correctly predict the anisotropy of the turbulent diffusivity tensor. The asymmetric nature of this tensor is also recovered, but only qualitatively, there being significant quantitative differences between the model predictions and the LES results. Finally, comparisons with data from benchmark two–dimensional free shear flows show the new model to yield distinct improvements over other algebraic scalar–flux closures.
Seasonal variation in photosynthetic capacity of montane conifers
Authors: NIPPERT J. B. , DUURSMA R. A. , MARSHALL J. D.
Published: December 2004

The capacity to perform photosynthesis, given appropriate environmental conditions, is reflected by measurements of the maximum quantum yield of photosystem II (Fv/Fm). The seasonal course ofFv/Fmmay help define the length of the annual photosynthetic period in temperate evergreen forests.

Fv/Fmwas measured 31 times from September to May on six conifer species located along an altitudinal gradient between 400 and 1400 m a.s.l. in northern Idaho, USA. The species were Western Redcedar (Thuja plicataDonn ex D. Donn), Douglas Fir (Pseudotsuga menziesii(Beissn.) Franco), Engelmann Spruce (Picea engelmanniiParry), Grand Fir (Abies grandis(Dougl.) Lindl.), Ponderosa Pine (Pinus ponderosaLaws.) and Lodgepole Pine (Pinus contortaDougl.).

Species differed in meanFv/Fm, in magnitude of response to maximum and minimum temperature, and in altitude effects other than temperature. For two speciesFv/Fmin spring differed from that in autumn, even when measured at the same air temperature. Regardless of temperature, most species maintained some photosynthetic capacity all winter.

A lag of several days to 2 months was observed in the response ofFv/Fmto ambient temperature. The lag differed among species. It was not observed in Grand Fir, and was as long as 2 months in Western Redcedar. Over all species combined the best overall correlation was with a moving average of maximum temperature over the previous 30 days.

The correlation betweenFv/Fmand maximum temperature was generally stronger than that with minimum temperature (average root mean‐squared error was reduced by 10%), presumably because maximum temperatures better reflect daytime photoinhibitory conditions.

A reduced model predictedFv/Fmbased on species and maximum temperature; this model can be used to parameterize models describing the annual cycle of photosynthetic capacity for the six conifer species included in this study.
Murray's law and the hydraulicvsmechanical functioning of wood
Authors: McCULLOH K. A. , SPERRY J. S. , ADLER F. R.
Published: December 2004

Murray's law states that the hydraulic conductance per blood volume of the cardiovascular system is maximized when the sum of the vessel radii cubed (Σ r3) is conserved.

We hypothesize that Murray's law will apply to xylem conduits as long as they only transport water and do not also help support the plant. Specifically, the less volume of wood occupied by conduits, the more the conduits should conform to Murray's law.

We tested the applicability of Murray's law along a continuum of decreasing conduit fraction from coniferous (91% conduits) to diffuse‐porous (24% conduits) to ring‐porous wood (12% conduits), using anatomical and functional tests. The anatomical test compared the Σ r3conservation across branch points by direct measurements of conduit radii. The functional test compared the hydraulic conductivity between branches of different ages.

As predicted, Murray's law was rejected in conifer wood where hydraulic function is coupled to mechanical support. The angiosperm wood did not deviate as strongly from Murray's law, especially the ring‐porous type. For comparison we report previously published results from compound leaves and vines which showed general agreement with Murray's law.

Deviation from Murray's law was associated with fewer, narrower conduits distally causing a decrease in Σ r3distally. Although less efficient hydraulically, this configuration is not top‐heavy and is more mechanically stable. With the evolution of vessels and fibres, angiosperm wood can more closely approach Murray's law while still meeting mechanical requirements.
Linking the foraging performance of a marine predator to local prey abundance
Authors: GRÉMILLET D. , KUNTZ G. , DELBART F. , MELLET M. , KATO A. , ROBIN J.‐P. , CHAILLON P.‐E. , GENDNER J.‐P. , LORENTSEN S.‐H. , MAHO Y. LE
Published: December 2004

Knowledge of the functional response of predators to prey densities conditions our understanding of food webs. Such links are still poorly understood within the higher trophic levels of marine ecosystems.

We present the first field study recording the foraging effort and foraging yield of a seabird (the Great Cormorant, Phalacrocorax carbo) as well as the abundance and quality of prey within its foraging area.

We confirm that Great Cormorants foraging off West‐Greenland show the highest foraging performance recorded for a marine predator (between 17 and 41 g fish caught per minute underwater). Former work suggests that such high foraging yield should be based upon the exploitation of extremely profitable prey patches.

Contrary to this hypothesis, average prey abundances estimated within the foraging areas of the cormorants were low (0·03–0·09 prey m−2, depending on methods), as was the average calorific value of the prey items (4·2 kJ g−1).

Our study suggests that Great Cormorants remain highly successful predators even when exploiting modest prey resources. These findings have implications for our understanding of predator–prey relationships, and for the management of Great Cormorant populations.
Starvation resistance in Drosophila melanogaster: testing for a possible ‘cannibalism’ bias
Authors: HUEY R. B. , SUESS J. , HAMILTON H. , GILCHRIST G. W.
Published: December 2004

Starvation resistance is often measured in physiological studies with Drosophila and other insects. One common method involves measuring time until death of groups of insects. This method assumes that survivors are not obtaining nutrition from their vial mates that die early. However, because some Drosophila larvae can scavenge carcasses, this group protocol might inadvertently lead to a ‘cannibalism’ bias.

We evaluated whether starvation resistance of Drosophila melanogaster was increased if fly carcasses were available from the beginning of the experiment. We used a mixed‐model anova to assess the direct and interactive effects of isofemale line, sex and immediate access to carcasses.

Males survived starvation longer than females, despite the smaller size of males. Isofemale lines differed significantly in resistance. Immediate access to fly carcasses had no impact on resistance.

These results suggest that starving adult flies do not gain measurable benefits from access to carcasses. Consequently, this experiment seemingly validates a widely used method of measuring starvation resistance.
HPLC sugar analysis reveals the nutritional state and the feeding history of parasitoids
Authors: STEPPUHN A. , WÄCKERS F. L.
Published: December 2004

Adult parasitoids depend on sugar‐rich foods such as nectar and honeydew to meet their energy requirements. Many laboratory studies have established fitness benefits of sugar feeding for parasitoids.

Nevertheless, we know little about the nutritional ecology of parasitoids in the field, chiefly because of the limited specificity of methods applicable for field studies.

Here we use high‐performance liquid chromatography (HPLC) analysis to study the sugar profile of Cotesia glomerata L. and Microplitis mediator Haliday relative to feeding‐treatment. We identify the overall sugar level and the ratio of glucose to fructose as two parameters that in combination unambiguously characterize an individual's nutritional state and feeding history.

Unfed parasitoids contained low total sugar levels and glucose levels that typically exceeded fructose levels more than five‐fold. Parasitoids with constant access to sucrose had high overall sugar levels with a balanced glucose–fructose ratio.

The marked shift of the glucose–fructose ratio after feeding was still evident in C. glomerata individuals whose total sugar content had decreased to unfed levels after 3 days of starvation. This makes it possible to distinguish between unfed individuals and those that did feed several days ago.

In addition to revealing past feeding events, HPLC analysis also enables the identification and quantification of a wide spectrum of sugars present in each specimen. When food sources contain specific sugars this can provide additional information about the type of sugar source consumed.

HPLC analyses revealed that trehalose, considered to be the ‘insect haemolymph sugar’, is not present in the two species investigated here.

Overall, HPLC sugar analysis provides a powerful tool to investigate energy status, feeding history and nutritional physiology of field‐collected parasitoids.
Inflorescence architecture and wind pollination in six grass species
Authors: FRIEDMAN JANNICE , HARDER LAWRENCE D.
Published: December 2004

Inflorescence architecture and floral morphology vary extensively within the Poaceae, but the functional significance of this variation remains largely unknown. As grasses are wind‐pollinated, their inflorescence diversity probably reflects alternate solutions to manipulating airstreams to enhance pollen export and import. We tested this hypothesis with two field experiments that contrasted pollen removal and receipt by compact and diffuse inflorescences.

In the ‘aggregation’ experiment, we tied together panicle branches of two species with diffuse inflorescences, creating more compact inflorescences. Aggregation reduced pollen removal from both species, probably by increasing boundary‐layer thickness. The effects of inflorescence aggregation differed between the two species in a manner that is consistent with pollen‐size differences, which could affect the ability of pollen grains to pass through the thickened boundary layer around stigmas.

The ‘staking’ experiment constrained inflorescence motion and revealed that culm characteristics contribute to the interaction between grass inflorescences and airstreams. In particular, inflorescence oscillation principally serves pollen removal for species with compact inflorescences, but is of primary importance in pollen receipt for species with diffuse architectures.

These results suggest that inflorescence architecture interacts with wind in a complex manner to facilitate pollination and supports the hypothesis that the extensive diversity of inflorescence architecture within the Poaceae represents evolutionary solutions to the physical constraints of wind pollination.
Limited ability of Palestine SunbirdsNectarinia oseato cope with pyridine alkaloids in nectar of Tree TobaccoNicotiana glauca
Authors: TADMOR‐MELAMED H. , MARKMAN S. , ARIELI A. , DISTL M. , WINK M. , IZHAKI I.
Published: December 2004

Secondary compounds are common in floral nectar but their relative effects on nectar consumption and utilization in nectarivorous birds are unclear.

We studied the effect of two pyridine alkaloids, nicotine and anabasine, present in Tree Tobacco (Nicotiana glauca) nectar, on food consumption, gut transit time and sugar assimilation efficiency of the Palestine Sunbird (Nectarinia osea), a pollinator ofN. glaucain east Mediterranean ecosystems.

Sunbirds demonstrated dose‐dependent deterrence; they were not deterred by the lowest natural concentrations of these alkaloids in nectar (0·1 ppm nicotine and 0·6 ppm anabasine) but they were significantly deterred by the average concentrations detected in nectar (0·5 ppm nicotine and 5 ppm anabasine).

The two pyridine alkaloids reduced gut transit time (by 30–42%) and sugar assimilation efficiency (by 9–17%) compared with the control alkaloid‐free diet.

Sunbirds are able to cope with low, but not average, concentrations of nicotine and anabasine inN. glaucanectar. If sunbirds are efficient pollinators ofN. glaucathey may induce selection on it to reduce pyridine alkaloid production in the nectar. Alternatively, high concentrations in someN. glaucaplants may lead the birds to visit more plants with lower alkaloid concentrations. Hence, they will be more efficient pollinators, especially if other nectar‐producing plants are scarce.
Response of host species to brood parasitism in dung beetles: importance of nest location by parasitic species
Authors: GONZÁLEZ‐MEGÍAS A. , SÁNCHEZ‐PIÑERO F.
Published: December 2004

Brood parasitism is an interaction that negatively affects reproductive success of host species, some of which have evolved defences to reduce offspring mortality caused by the parasites. In this study, we analyse the responses to interspecific brood parasitism of a dung beetle species,Onthophagus merdarius, in which reproductive success is heavily affected by parasitic beetles.

We used a combination of field and laboratory experiments to approach this question. Manipulating the effect of the presence of brood parasites on host nesting showed that there were no differences between treatments in nest traits. This absence of responses of the host species might be related to how and when brood parasites localize host nests: brood parasites actively find host nests after the nests have been finished and the nest burrows sealed.

Although both the rate of parasitism and the mortality rate caused by parasites are very high onO. merdarius, the possibility of the host species to evolve defence strategies against brood parasites is probably constrained by resource limitation for nesting in the study area. Because brood parasitism and resource limitation act synergistically favouring small brood size and small brood‐mass size, smaller individuals may be also favoured under these conditions in the study area.
Pharmacokinetic/pharmacodynamic relationships of antimicrobial drugs used in veterinary medicine
Authors: MCKELLAR Q. A. , SANCHEZ BRUNI S. F. , JONES D. G.
Published: December 2004

The rise in incidence of antimicrobial resistance, consumer demands and improved understanding of antimicrobial action has encouraged international agencies to review the use of antimicrobial drugs. More detailed understanding of relationships between the pharmacokinetics (PK) of antimicrobial drugs in target animal species and their action on target pathogens [pharmacodynamics (PD)] has led to greater sophistication in design of dosage schedules which improve the activity and reduce the selection pressure for resistance in antimicrobial therapy. This, in turn, may be informative in the pharmaceutical development of antimicrobial drugs and in their selection and clinical utility. PK/PD relationships between area under the concentration time curve from zero to 24 h (AUC0‐‐24) and minimum inhibitory concentration (MIC), maximum plasma concentration (Cmax) andMICand time during which plasma concentrations exceed theMIChave been particularly useful in optimizing efficacy and minimizing resistance. Antimicrobial drugs have been classified as concentration‐dependent where increasing concentrations at the locus of infection improve bacterial kill, or time‐dependent where exceeding theMICfor a prolonged percentage of the inter‐dosing interval correlates with improved efficacy. For the latter group increasing the absolute concentration obtained above a threshold does not improve efficacy. The PK/PD relationship for each group of antimicrobial drugs is ‘bug and drug’ specific, although ratios of 125 forAUC0‐‐24:MICand 10 forCmax:MIChave been recommended to achieve high efficacy for concentration‐dependent antimicrobial drugs, and exceedingMICby 1–5 multiples for between 40 and 100% of the inter‐dosing interval is appropriate for most time‐dependent agents. Fluoroquinolones, aminoglycosides and metronidazole are concentration‐dependent and beta‐lactams, macrolides, lincosamides and glycopeptides are time‐dependent. For drugs of other classes there is limited and conflicting information on their classification. Resistance selection may be reduced for concentration‐dependent antimicrobials by achieving anAUC0‐‐24:MICratio of greater than 100 or aCmax:MICratio of greater than 8. The relationships between time greater thanMICand resistance selection for time‐dependent antimicrobials have not been well characterized.
Bioavailability and its assessment
Authors: TOUTAIN P. L. , BOUSQUET‐MÉLOU A.
Published: December 2004

Bioavailability is a key pharmacokinetic parameter which expresses the proportion of a drug administered by any nonvascular route that gains access to the systemic circulation. Presented in this review are the different approaches to measurement of bioavailability (absolute and relative), including the case in which intravenous administration is impossible. The rate of drug absorption is also discussed with special emphasis on the possible difficulties encountered usingCmaxandTmaxor curve fitting to evaluate the rate of drug absorption.
Plasma clearance
Authors: TOUTAIN P. L. , BOUSQUET‐MÉLOU A.
Published: December 2004

Plasma (total, systemic…) clearance is determined by all the individual metabolizing/eliminating organ clearances and involves mainly liver and kidney clearances. Plasma clearance (a volume per time, i.e. a flow) expresses the overall ability of the body to eliminate a drug by scaling the drug elimination rate (amount per time) by the corresponding plasma concentration level. The interpretation of plasma clearance and inter‐species comparisons are made easier by computing the overall body extraction ratio (from 0 to 1), which is the ratio of the body clearance divided by cardiac output. Plasma clearance is the most important pharmacokinetic parameter because it is the only one which controls the overall drug exposure (for a given bioavailability) and it is the parameter which allows computation of the dosage required to maintain an average steady‐state plasma concentration.
Integration and modelling of pharmacokinetic and pharmacodynamic data to optimize dosage regimens in veterinary medicine
Authors: TOUTAIN P. L. , LEES P.
Published: December 2004

In veterinary drug development procedures, pharmacokinetic (PK) and pharmacodynamic (PD) data have generally been established in separate, parallel studies to assist in the design of dosage schedules for subsequent evaluation in clinical trials. This review introduces the concept of PK/PD modelling, an approach in which PK and PD data are generated in the same study, and used to derive numerical values for PD parameters based on drug plasma concentrations. The PD parameters define the efficacy, potency and slope (sensitivity) of the concentration–effect relationship. It is proposed that the parameters derived from PK/PD modelling may be used as an alternative and preferred approach to dose titration studies for selecting rational dosage regimens (both dose and dosing interval) for further evaluation in clinical trials. In PK/PD modelling, the explicative variable for effect is the plasma concentration profile. The PK/PD approach provides several advantages over dose‐titration studies, including determination of a projected dosage regimen by investigation of a single dose, in contrast to dose‐ranging studies which by definition require testing of multiple dosage. Implementation of PK/PD modelling in the veterinary drug development process is currently constrained by the limited number of veterinary studies performed to date, and the consequently limited understanding of PK/PD concepts and their absence from regulatory authority guidelines. Nevertheless, PK/PD modelling has major potential for rational dosage regimen determination, as it considers and quantifies the two main sources of interspecies variability (PK and PD). It is therefore applicable to interspecies extrapolation and to multiple species drug development. As well as the currently limited appreciation of PK/PD principles in the veterinary scientific community, a further constraint in implementing PK/PD modelling is the need to validate PK/PD approaches and thereby gain confidence in its value by pharmaceutical companies and regulatory authorities.
Pharmacodynamics and pharmacokinetics of nonsteroidal anti‐inflammatory drugs in species of veterinary interest
Authors: LEES P. , LANDONI M. F. , Giraudel J. , TOUTAIN P. L.
Published: December 2004

This review summarises selected aspects of the pharmacokinetics (PK) and pharmacodynamics (PD) of nonsteroidal anti‐inflammatory drugs (NSAIDs). It isnotintended to be comprehensive, in that it covers neither minor species nor several important aspects of NSAID PD. The limited objective of the review is to summarise those aspects of NSAID PK and PD, which are important to an understanding of PK–PD integration and PK–PD modelling (the subject of the next review in this issue). The general features of NSAID PK are: usually good bioavailability from oral, intramuscular and subcutaneous administration routes (but with delayed absorption in horses and ruminants after oral dosing), a high degree of binding to plasma protein, low volumes of distribution, limited excretion of administered dose as parent drug in urine, marked inter‐species differences in clearance and elimination half‐life and ready penetration into and slow clearance from acute inflammatory exudate.

The therapeutic effects of NSAIDs are exerted both locally (at peripheral inflammatory sites) and centrally. There is widespread acceptance that the principal mechanism of action (both PD and toxicodynamics) of NSAIDs at the molecular level comprises inhibition of cyclooxygenase (COX), an enzyme in the arachidonic acid cascade, which generates inflammatory mediators of the prostaglandin group. However, NSAIDs possess also many other actions at the molecular level. Two isoforms of COX have been identified. Inhibition of COX‐1 is likely to account for most of the side‐effects of NSAIDs (gastrointestinal irritation, renotoxicity and inhibition of blood clotting) but a minor contribution also to some of the therapeutic effects (analgesic and anti‐inflammatory actions) cannot be excluded. Inhibition of COX‐2 accounts for most and possibly all of the therapeutic effects of NSAIDs. Consequently, there has been an intensive search to identify and develop drugs with selectivity for inhibition of COX‐2. Whole bloodin vitroassays are used to investigate quantitatively the three key PD parameters (efficacy, potency and sensitivity) for NSAID inhibition of COX isoforms, providing data on COX‐1:COX‐2 inhibition ratios. Limited published data point to species differences in NSAID‐induced COX inhibition, for both potency and potency ratios. Members of the 2‐arylpropionate sub‐groups of NSAIDs exist in two enantiomeric forms [R‐(−) andS‐(+)] and are licensed as racemic mixtures. For these drugs there are marked enantiomeric differences in PK and PD properties of individual drugs in a given species, as well as important species differences in both PK and PD properties.
Polychaete Fauna of Seagrass Beds (Halodule wrightii Ascherson) Along the Coast of Rio de Janeiro (Southeast Brazil)
Authors: Omena Elianne , Creed Joel C.
Published: December 2004

Abstract.  The polychaete community structure from six Halodule wrightii seagrass beds along the Rio de Janeiro coast (Southeast Brazil) was investigated. Variations in species diversity, overall density and species composition in relation to sediment grain size, seagrass biomass and selected plant structural features such as root and shoot length from the study sites were analysed. Ten core samples (0.02 m2) were randomly collected from each site. Three additional samples were taken for grain size analysis of sediment. Sixty‐eight species of polychaetes belonging to 24 families were found. The dominant species as well as species composition varied greatly among sites, showing that a typical polychaete community does not exist. The number of species was positively correlated with the silt‐clay percent and sorting coefficient of the sediment. A positive correlation between polychaete density and plant biomass was also obtained. Multivariate analysis indicated that polychaete communities were influenced greatly by seagrass plant features: plants with longer shoots harbour mainly surface‐deposit feeders such as Magelona papillicornis, whereas plants with a higher root‐shoot length relation sheltered mainly suspension or interface feeders like Fabricia filamentosa. This study demonstrates that granulometric properties as well as plant architecture play an important role in structuring the polychaete community. As the community‐level response can reflect changes in local seagrass beds, the structure of the polychaete community can be an important indicator for management plans and the restoration of seagrass ecosystems.
Dinoflagellate Cysts in Recent Sediments from Chinese Coastal Waters
Authors: Wang Zhaohui , Matsuoka Kazumi , Qi Yuzao , Chen Jufang
Published: December 2004

Abstract. Surface sediments were collected from 10 locations to study the distribution of dinoflagellate resting cysts in Chinese coastal waters from July 2000 to May 2002. Sixty‐one cyst morphotypes representing 14 genera of three orders were identified in this survey. Seventeen cyst types were recorded for the first time from Chinese coasts. Rich cyst assemblages were recorded in closed or semi‐closed nearshore harbors.Scrippsiella trochoideawas the most dominant and common cyst type in this survey, especially in sediments from Daya Bay, Dapeng Bay and Shenzhen Bay. However,Protoperidiniumcysts were the most diversified group, predominating in Changjiang River Estuary, Zhujiang River Estuary, Zhelin bay and the Nanao Island area. Cyst concentrations in the top 2 cm surface sediments varied from 258 to 25,037 cysts·g−1dry weight sediment, and abundance was lower in Changjiang River Estuary and Zhujiang River Estuary. Cysts of two dinoflagellates capable of producing paralytic shellfish poisoning (PSP) –Alexandriumspp. andGymnodinium catenatum– were detected almost in all locations. Furthermore, the ellipsoidalAlexandrium catenellaandA. tamarensecyst complex was frequently observed in the surface sediment from Daya Bay, where high contents of PSP toxin and PSP episodes have been reported. Detailed descriptions and illustrations are provided of those cysts of newly recorded species, unidentified species, toxic species and dominant species.
Mapping Growth into Economic Development
Authors: Fosu Augustin Kwasi
Published: December 2004

Abstract. The study finds that elite political instability (PI)—the incidence of coups d’etat—has negatively influenced the mapping of GDP growth into economic development, measured as the algebraic difference in the United Nations Human Development Index, in Sub‐Saharan Africa (SSA) between 1970 and 1985. Taking into account the additional adverse impact of PI on economic development through its deleterious influence on economic growth, the study estimates that PI has exacted a substantial toll in SSA's economic development.
Modeling three-dimensional elastic wave propagation in circular cylindrical structures using a finite-difference approach
Authors: Gsell Daniel , Leutenegger Tobias , Dual Jürg
Published: December 2004

Wave propagation along circular cylindrical structures is important for nondestructive-testing applications and shocks in tubes. To simulate elastic wave propagation phenomena in such structures the governing equations in cylindrical coordinates are solved numerically. To reduce the required amount of computer memory and the computational time, the stress components are eliminated in the equilibrium equations. In the resulting coupled partial differential equations, in which only the three displacement components are involved, the derivatives with respect to spatial coordinates and time are approximated using second order central differences. This leads to the present new approach, which is both accurate and efficient. In order to obtain a stable scheme the displacements must be allocated on a staggered grid. The von Neumann stability analysis is performed and the result is compared with an existing empirical criterion. Mechanical energies are observed in order to validate the finite-difference code. Since no material damping or energy dissipation is taken into account in the equations of motion, the total energy must remain constant over time. Only negligible variations are observed during long-term simulations. Dispersion relations are used to check the physical behavior of the waves calculated with the proposed finite-difference method: Theoretically calculated curves are compared with values obtained by a spectrum estimation method, applied to the results of a simulation.
Multiple-order derivatives of a waveguide acoustic field with respect to sound speed, density, and frequency
Authors: Thode Aaron , Kim Katherine
Published: December 2004

An adjoint perturbative method is used to derive expressions for the first- through third-order derivatives of a pressure field with respect to sound speed, density, and frequency, for the restricted case of a laterally homogenous waveguide in which environmental parameters are only a function of depth. By using a normal-mode Green’s function, the three-dimensional spatial correlation required by the standard acoustic adjoint equation can be reduced to a set of one-dimensional depth integrals. The resulting expressions for the first-order derivative are similar to those obtained by previous perturbative approaches based on the depth-separated wave equation, but the approach followed here permits straightforward extension to higher-order derivatives. Explicit evaluations of the expressions for a representative shallow-water waveguide model are in excellent agreement with numerical finite-difference computations. An analysis of the expressions as a function of source-receiver range finds the contributions to the mode amplitude derivatives to be non-negligible at ranges less than a few modal interference lengths, for parameters associated with the ocean bottom. Therefore, linear perturbative inversion methods that perturb only horizontal wavenumbers and not mode amplitudes should either be used with caution or modified to incorporate the expressions presented here.