bluuebunny/crossref_metadata_2025 huggingface dataset:
The Efffect of Work Interruptions on Women’s Wages
Authors: Baum Charles L.
Published: December 2004

This paper examines the effects of work interruptions on women’s wages, focusing particularly on work interruptions to give birth. It also accounts for whether mothers return to work at their pre‐childbirth jobs after giving birth. The results show that work interruptions in general and work interruptions specifically to give birth reduce wages. However, the negative effects of work interruptions to give birth are at least partially eliminated when controlling for whether mothers return to work for their pre‐childbirth employers. Also, these effects are temporary and do not persist beyond the second year after returning to work.
Employment Adjustment at the Firm Level. A Theoretical Model and an Empirical Investigation for West German Manufacturing Firms
Authors: Smolny Werner
Published: December 2004

In this paper, employment adjustment at the firm level is estimated with a large panel of business survey data from West German manufacturing. The specification is based on a framework of monopolistic competition in the product market. Special emphasis is devoted to the analysis of the impact of demand uncertainty, capacity constraints, technological change and competition. The empirical results reveal that demand uncertainty and capacity constraints significantly affect employment adjustment. Innovative firms are more successful; they increase employment and exhibit a higher utilization of capacities. Employment adjustment also depends on competition. In monopolistic markets, the volatility of employment is higher.
Modelling Traded, Non‐traded and Aggregate Inflation in a Small Open Economy: The Case of Ireland
Authors: Kenny Geoff , McGettigan Donal
Published: December 2004

This paper addresses the unresolved issues surrounding the determination of Irish inflation. The study tests the validity of (i) a pure wage mark‐up model, (ii) a pure small open economy model and (iii) a hybrid model which fuses elements of (i) and (ii) over the period 1979Q1–1995Q3. Multivariate cointegration techniques are employed to clearly distinguish the long‐run and short‐run information in the data. The results highlight the relevance of the distinction between traded and non‐traded prices. For traded prices, full purchasing power parity (PPP) was found to be consistent with the data. In the case of non‐traded prices, the data reject strict long‐run PPP. Aggregate price results occupy an intermediate position. Finally, we demonstrate that strong bi‐directional feedback exists between prices and wages.
Inflation Dynamics in a New Keynesian Model
Authors: Ireland Jonathan , Wren‐Lewis Simon
Published: December 2004

A New Keynesian model is used to derive a relationship between current and expected future inflation taking into account future inflationary pressure. This relationship is employed to examine inflationary dynamics resulting from real disturbances to the economy. Positive current inflationary pressure can be associated with either rising or falling inflation—a phenomenon which has received little attention to date. A data‐based model of the UK is used to provide further evidence on the nature of the response of inflation to real disturbances and to quantify the importance of inertia in goods and labour markets.
Exchange Rate Hysteresis from Trade Account Interaction
Authors: McCausland W. David
Published: December 2004

An explicitly specified macro model of exchange rate determination is integrated with a model of trade account hysteresis. In this macro model, flow imbalances in the trade account must be matched by equilibrating stocks of imperfectly substitutable assets, generating a stock–flow consistent determination of the exchange rate. In this paper, changes in the real exchange rate induce firms to enter particular markets for internationally traded goods, which in turn affects the trade balance. When there are sunk costs associated with this entry, returning the real exchange rate to its initial state may not induce those firms to exit the markets that they have entered. This causes trade account hysteresis. Since the real exchange rate is in part determined by the trade balance, trade account hysteresis feeds through to give exchange rate hysteresis.
The Defaultable Lévy Term Structure: Ratings and Restructuring
Authors: Eberlein Ernst , Özkan Fehmi
Published: December 2004

We introduce the intensity‐based defaultable Lévy term structure model. It generalizes the default‐free Lévy term structure model by Eberlein and Raible, and the intensity‐based defaultable Heath‐Jarrow‐Morton approach of Bielecki and Rutkowski. Furthermore, we include the concept of multiple defaults, based on Schönbucher, within this generalization.
A General Fractional White Noise Theory And Applications To Finance
Authors: Elliott Robert J. , Van Der Hoek John
Published: December 2004

We present a new framework for fractional Brownian motion in which processes with all indices can be considered under the same probability measure. Our results extend recent contributions by Hu, Øksendal, Duncan, Pasik‐Duncan, and others. As an application we develop option pricing in a fractional Black‐Scholes market with a noise process driven by a sum of fractional Brownian motions with various Hurst indices.
Towards ‘Accountable Independence’? Parliamentary Controls of the European Central Bank and the Rise of a New Democratic Model
Authors: Magnette Paul
Published: December 2004

The independence of the European Central Bank is legally defined in very clear and strict terms. Although most scholars in economics describe this status as a crucial condition of the Bank's efficiency, it is frequently criticised by politicians and political scientists as a contradiction to democratic theory.

This paper will examine the emerging practice of parliamentary control of the ECB, from its installation until September 1999, in order to understand which kind of ‘accountability’ is elaborated in this unprecedented relationship between ‘politicians’ and lsquo;technocrats’.

 It will first show that MEPs have rejected all forms of parliamentary control based on a logic of constraint. It will then describe the numerous institutional links created between the Bank and the EU political organs to favour their cooperation. Finally it will analyse the recent initiatives taken by MEPs to influence central bankers and to convince them to submit their decisions to public debates.

The hypothesis developed from these empirical analyses is that a new kind of ‘accountability’ is emerging in the EU. From a horizontal point of view (inter‐institutional controls), it is based on influence rather than traditional parliamentary constraint. From a vertical point of view (accountability to citizens), it focuses on responsiveness rather than on classic responsibility.
Crumbling Ivory Towers: Academic Organizing and its Gender Effects
Authors: Benschop Yvonne , Brouns Margo
Published: December 2004

The under‐representation of women at the top of the academy is a persistent and fascinating issue, mostly analysed as a result of women's choices or as an issue of personnel management. In this article, the focus is on the functioning of universities as social institutions, where gender is ‘done’ in a specific way. We analyse how the structural, cultural and procedural arrangements of academic organizing constitute gender relations and are specifically interested in the social construction of scientific quality. The ‘normal’ standards for scientific quality reflect the traditions of the natural sciences, with the Olympus as dominant image: the excellent scientist as lonely hero at the top, far distanced from everyday practices. This conception reflects a hegemonic position privileging masculinity. Alternatively, in an Agora model, science is not an autonomous institution, but becomes a societal practice tightly bound with other societal practices concerning the production, transmission, translation and exchange of knowledge. The scientific ideal of the Agora entails greater public accountability, social responsibility and transparency. This model reflects to a certain extent the scientific activities and achievements of female scientists, and we expect that gender will be done differently in it. In our view, the integration and mainstreaming of gender issues within the academy will serve as a strong impetus to the necessary modernization of academia and academic organizing. But this implies a critical reflection on the social constructed nature of any conception of ‘quality’.
Intertwined Discourses of Merit and Gender: Evidence from Academic Employment in the USA
Authors: Krefting Linda A.
Published: December 2004

In the USA women currently gain about 44% of doctoral degrees and a similar share of initial academic appointments. However, overall women hold about 33% of faculty positions and are slower to earn tenure and be promoted to full professor. Academic achievements have lower salary payoff for women, and they earn less than men with comparable qualifications and accomplishments. In the micropolitics of academic life, women remain on the margin trying to prove they have the skills to ‘play the game at all’ while men realistically presume support and focus on strategizing reputation (Gersick et al., 2000). The gendered nature of academic life in the USA is interpreted in terms of Glick and Fiske's ‘ambivalent sexism’. In this view, gender stereotypes are ideological and prescriptive rather than simply descriptive; their influence on academic employment processes is unlikely to diminish simply with the passage of time or accumulating evidence on women's capabilities. While insightful, alone this framing leads to the pessimistic view that ambivalent attitudes toward women are intractable. Adding a feminist perspective on discourse allows a somewhat more optimistic view: intertwined discourses of gender and merit are sufficiently complex and heterogeneous to provide openings for resistance, renegotiation, and rewriting.
Pension Reform, Capital Markets and the Rate of Return
Authors: Börsch-Supan Axel , Ludwig Alexander , Heiss Florian , Winter Joachim
Published: December 2004

This paper discusses the consequences of population aging and a fundamental pension reform - that is, a shift towards more pre-funding - for capital markets in Germany. We use a stylized closed-economy, overlapping-generations model to compare the effects of the recent German pension reform with those of a more decisive reform that would freeze the current pay-as-you-go contribution rate and thus result in a larger funded component of the pension system.We predict rates of return to capital under both reform scenarios over a long horizon, taking demographic projections as given. Our main finding is that the future decrease in the rate of return is much smaller than often claimed in the public debate. Our simulations show that the capital stock will decrease once the baby-boom generations enter retirement, even if there were no fundamental pension reform. The corresponding decrease in the rate of return, the direct effect of population aging, is around 0.7 percentage points. While the capital market effects of the recent German pension reform are marginal, the rate of return to capital would decrease by an additional 0.5 percentage points under the more decisive reform proposal.
Supply-Side Economics of Germany’s Year 2000 Tax Reform: A Quantitative Assessment
Authors: Strulik Holger
Published: December 2004

The paper provides an assessment of supply-side economics following Germany’s year 2000 tax reform. Investigated are a corporate tax cut, deteriorating depreciation allowances and imputation rules, and a private income tax cut. For this purpose, a neoclassical growth model is augmented by various fiscal policy parameters and endogenous corporate finance and calibrated with German data. The model is used to evaluate consequences of Germany’s tax reform on production, firm finance and leverage, investment, consumption and welfare of a representative household.
The Effect of Communication Media on Cooperation
Authors: Brosig Jeannette , Weimann Joachim
Published: December 2004

We examine how communication affects cooperation with the help of seven standard public goods experiments that only differ with respect to the medium of pre-play communication. Our treatments include bidirectional and unidirectional communication via (mostly electronic) auditory and/or visual channels. The results suggest that successful cooperation is attributable to the opportunity of ‘coordinating’ behavior in the communication phase. Furthermore, both the level and the stability of cooperation significantly interact with the communication medium, even though the content of communication is remarkably similar across the communication treatments.
Determinants of the Loan Loss Allowance: Some Cross‐Country Comparisons
Authors: Hasan Iftekhar , Wall Larry D.
Published: December 2004

This paper analyzes the determinants of banks' loan loss allowance for samples of U.S. banks and three non‐U.S. samples: a group of 21 countries, Canada, and Japan. The model includes fundamental (or nondiscretionary) determinants of the allowance, such as nonperforming loans, and discretionary determinants, such as income before the loan loss provision. The results suggest that the loan loss allowance is sensitive to preprovision income in almost all samples. However, the results also suggest that some variables thought to reflect fundamental factors in U.S. analysis, such as net charge‐offs, are not significant factors for non‐U.S. banks.
The Relative Cost Efficiency of Stock versus Mutual Thrifts: A Bayesian Approach
Authors: Sfiridis James M. , Daniels Kenneth N.
Published: December 2004

The relative cost efficiency of the mutual versus stock forms of ownership for thrifts has been a relevant issue in an era of deregulation and competition in the financial services industry. In this study, Bayesian‐based Markov chain Monte Carlo (MCMC) resampling methods are used to solve a stochastic cost frontier model and effectively determine cost efficiencies for the stock and mutual thrift groups. We find a statistically significant difference between both the cost frontiers and the cost efficiencies of the two groups, with the stock group operating at the lower‐cost point. Agency problems explain a significant portion of the cost efficiency difference. Capital structure differences, though not helping to explain differences in cost efficiency, do help to explain differences in cost structure and managerial attitudes toward risk.
Usefulness of electron beam computed tomography for quantitative estimation of myocardial ischemia in patients
Authors: Endoh Hikosato , Tsukano Shinya , Ishikawa Yuichi , Takamuro Motoki , Tsuda Etsuko , Ono Yasuo , Arakaki Yoshio , Echigo Shigeyuki , Tanaka Ryoichi , Takamiya Makoto , Naito Hiroaki
Published: December 2004

Background
: The electron beam computed tomography (EBT) was used as non‐invasive methods for estimating mycardial characteristics in patients after onset of Kawasaki disease.

Methods
: All of the 22 coronary branches with localized stenosis (LS), and 22 branches without coronary artery lesion after Kawasaki disease were examined for changes of myocardial CT number. In this study, each myocardial region was divided into three parts (endocardial, central, epicardial parts) and the myocardium/lumen (M/L) ratio was calculated.

Results
: The mean M/L ratio in the endocardial part of early image with LS was significantly lower than the ratios in the other parts of early images with LS (P = 0.0286, P = 0.0069, respectively). and only the mean M/L ratio in the endocardial part was significantly different on images from patients with LS and images from patients without LS (P = 0.0296). Inverse correlations were found in the LS group between coronary artery stenosis rate determined by coronary angiography and M/L ratio in the endocardial part on early images (P = 0.0018, r = –0.614, y = 0.56 –0.605x).

Conclusions
: It was possible to quantitatively evalutate myocardial characteristics using EBT. It is suggested that myocardial ischemia progressed from the endocardial region and EBT is useful to detect the endocardial ischemia. We suggested that the rate of coronary stenosis in patients with LS can be estimated by calculating the M/L rations in the endocardial parts of early EBT images. EBT enables accurate evaluation of myocardial characteristics non‐invasively.
High‐dose idarubicin and busulphan as conditioning to autologous stem cell transplantation in adult patients with acute myeloid leukaemia
Authors: Ferrara Felicetto , Palmieri Salvatore , Simone Mariacarla De , Sagristani Marco , Viola Assunta , Pocali Barbara , Fasanaro Alfredo , Mele Giuseppina
Published: December 2004

Between 30 and 50% of patients with acute myeloid leukaemia (AML) relapse after autologous stem cell transplantation (ASCT). One possibility of reducing the relapse rate could be the adoption of conditioning regimens specifically designed for AML. We report treatment results achieved with a new conditioning for ASCT, based on high‐dose idarubicin (IDA) plus oral busulphan. Patients (n = 40) were conditioned with a regimen consisting of 3 d continuous intravenous infusion IDA at 20 mg/m2, followed by 4 d conventional dose oral busulphan. Unpurged peripheral blood stem cells were used in all cases. All patients had non‐M3‐AML and were in first complete remission (CR). The median number of CD34+ cells infused was 6·9 × 106/l (2·6–24). No case of transplant‐related mortality occurred. In all cases, left ventricular ejection fraction remained unmodified after ASCT. Thirty‐three of 40 patients (82%) had grade 3–4 mucositis requiring total parenteral nutrition in all cases. After a median follow up for surviving patients of 32 months from ASCT, 30 patients (75%) are alive and 26 (65%) are in continuous CR. Our data show that a conditioning regimen based on high‐dose IDA plus busulphan results in an encouraging reduction of the relapse rate after ASCT in AML.
Thermogenesis and respiration of inflorescences of the dead horse arum Helicodiceros muscivorus, a pseudo‐thermoregulatory aroid associated with fly pollination
Authors: Seymour R. S. , Gibernau M. , Ito K.
Published: December 2004

In central Corsica, Helicodiceros muscivorus (Schott ex. K. Koch) produces a protogynous inflorescence that resembles the anal area of a dead mammal and produces a foetid scent during the few hours after sunrise. Flies enter the floral chamber, pollinate the female florets and become trapped until the next morning, when pollen is shed from the male florets and the flies are released.

The exposed appendix exhibits a strong, unimodal episode of thermogenesis associated with scent production, reaching a maximum of 30 °C at 15 °C ambient temperature. The male florets in the floral chamber are highly thermogenic throughout the second night and generally maintain stable floret temperatures of about 24 °C at ambient temperatures down to 13 °C.

Maximum respiration rates of the appendix (0·45 µmol CO2 s−1 g−1) and the male florets (0·82 µmol s−1 g−1) may be the highest recorded for plant tissue.

Thermogenesis of the appendix does not depend on ambient temperature, but that of the male florets increases with decreasing ambient temperature in most cases. However, the pattern of heat production by the males appears related more to time than to ambient temperature, hence the term ‘pseudo‐thermoregulation’.

The behaviour and thoracic temperatures of flies emerging from captivity suggests that male floral warming does not enhance their activity.
Astroturf seed traps for studying hydrochory
Authors: Wolters M. , Geertsema J. , Chang E. R. , Veeneklaas R. M. , Carey P. D. , Bakker J. P.
Published: December 2004

Astroturf mats can effectively trap diaspores dispersed by tidal water.

Within four tidal inundations, up to 745 propagules per m2 and between three and eight different species per astroturf mat were trapped. Overall, 15 different species were collected on the astroturf mats, 10 of which were also present in the local vegetation. The other five species must have come from further away, making the method also suitable for studying long‐distance dispersal.

The seed‐retaining ability of the astroturf did not differ significantly for species with different seed characteristics.

The method will be useful for assessing actual seed dispersal at specific sites and over specific periods of time, and has particular relevance in predicting and evaluating the success of ecological restoration projects.
Identification and characterization of a novel Dvl‐binding protein that suppresses Wnt signalling pathway
Authors: Oshita Akihiko , Kishida Shosei , Kobayashi Hiroki , Michiue Tatsuo , Asahara Toshimasa , Asashima Makoto , Kikuchi Akira
Published: December 2004

Background:   Dvl is a cytoplasmic protein to regulate the stability of β‐catenin in the Wnt signalling pathway. However, the molecular mechanism by which Dvl regulates the Wnt signalling pathway is not fully understood.

Results:   We identified a novel protein that binds to Dvl and named it Daple. Daple consisted of 2009 amino acids with a high frequency of leucine residues and formed a homo‐oligomer. The C‐terminal three amino acids of Daple were necessary for binding to the region containing the PDZ domain of Dvl. Expression of Daple in mouse fibroblast L cells inhibited Wnt‐3a‐induced accumulation of β‐catenin. Furthermore, Daple inhibited Wnt‐3a‐dependent activation of T‐cell factor (Tcf) transcriptional activity. Expression of Daple in the dorsal region of Xenopus embryos inhibited axis formation, which is known to be regulated by the Wnt signalling pathway. Daple also inhibited Dvl‐induced secondary axis formation in Xenopus embryos.

Conclusions:   Daple binds to Dvl and functions as a negative regulator of the Wnt signalling pathway.
Crystal structure of the Pyrococcus horikoshii DNA primase‐UTP complex: implications for the mechanism of primer synthesis
Authors: Ito Nobutoshi , Nureki Osamu , Shirouzu Mikako , Yokoyama Shigeyuki , Hanaoka Fumio
Published: December 2004

Background:   In chromosomal DNA replication, DNA primase initiates the synthesis of a dinucleotide on a single‐stranded template DNA, and elongates it to form a primer RNA for the replicative DNA polymerase. Although the apo‐structure of an archaeal primase has been reported, the mechanism of primer synthesis by the eukaryotic‐type primase still remains to be elucidated.

Results:   In this study, we present the crystal structure of the eukaryotic‐type DNA primase from the hyperthermophilic archaeon (Pyrococcus horikoshii) with the uridine 5′‐triphosphate (UTP). In the present primase‐UTP complex, the primase binds the triphosphate moiety of the UTP at the active site, which includes Asp95, Asp97, and Asp280, the essential residues for the nucleotidyl transfer reaction.

Conclusion:   The nucleotide binding geometry in this complex explains the previous biochemical analyses of the eukaryotic primase. Based on the complex structure, we constructed a model between the DNA primase and a primer/template DNA for the primer synthesis. This model facilitates the comprehension of the reported features of DNA primase.
Traveltime computation by wavefront‐orientated ray tracing
Authors: Coman Radu , Gajewski Dirk
Published: December 2004

For multivalued traveltime computation on dense grids, we propose a wavefront‐orientated ray‐tracing (WRT) technique. At the source, we start with a few rays which are propagated stepwise through a smooth two‐dimensional (2D) velocity model. The ray field is examined at wavefronts and a new ray might be inserted between two adjacent rays if one of the following criteria is satisfied: (1) the distance between the two rays is larger than a predefined threshold; (2) the difference in wavefront curvature between the rays is larger than a predefined threshold; (3) the adjacent rays intersect. The last two criteria may lead to oversampling by rays in caustic regions. To avoid this oversampling, we do not insert a ray if the distance between adjacent rays is smaller than a predefined threshold. We insert the new ray by tracing it from the source. This approach leads to an improved accuracy compared with the insertion of a new ray by interpolation, which is the method usually applied in wavefront construction. The traveltimes computed along the rays are used for the estimation of traveltimes on a rectangular grid. This estimation is carried out within a region bounded by adjacent wavefronts and rays. As for the insertion criterion, we consider the wavefront curvature and extrapolate the traveltimes, up to the second order, from the intersection points between rays and wavefronts to a gridpoint. The extrapolated values are weighted with respect to the distances to wavefronts and rays. Because dynamic ray tracing is not applied, we approximate the wavefront curvature at a given point using the slowness vector at this point and an adjacent point on the same wavefront. The efficiency of the WRT technique is strongly dependent on the input parameters which control the wavefront and ray densities. On the basis of traveltimes computed in a smoothed Marmousi model, we analyse these dependences and suggest some rules for a correct choice of input parameters. With suitable input parameters, the WRT technique allows an accurate traveltime computation using a small number of rays and wavefronts.
Depth and structural index from normalized local wavenumber of 2D magnetic anomalies
Authors: Salem Ahmed , Smith Richard
Published: December 2004

Recent improvements in the local wavenumber approach have made it possible to estimate both the depth and model type of buried bodies from magnetic data. However, these improvements require calculation of third‐order derivatives of the magnetic field, which greatly enhances noise. As a result, the improvements are restricted to data of high quality. We present an alternative method to estimate both the depth and model type using the first‐order local wavenumber approach without the need for third‐order derivatives of the field. Our method is based on normalization of the first‐order local wavenumber anomalies and provides a generalized equation to estimate the depth of some 2D magnetic sources regardless of the source structure. Information about the nature of the sources is obtained after the source location has been estimated. The method was tested using synthetic magnetic anomaly data with random noise and using three field examples.
Drought controls over conductance and assimilation of a Mediterranean evergreen ecosystem: scaling from leaf to canopy
Authors: Rambal Serge , Ourcival Jean‐Marc , Joffre Richard , Mouillot Florent , Nouvellon Yann , Reichstein Markus , Rocheteau Alain
Published: December 2004

Drought control over conductance and assimilation was assessed using eddy flux and meteorological data monitored during four summer periods from 1998 to 2001 above a closed canopy of the Mediterranean evergreen oak tree Quercus ilex. Additional discrete measurements of soil water content and predawn leaf water potential were used to characterize the severity of the drought.

Canopy conductance was estimated through the big‐leaf approach of Penman–Monteith by inverting latent heat fluxes. The gross primary production (GPP) was estimated by adding ecosystem respiration to net ecosystem exchange. Ecosystem respiration was deduced from night flux when friction velocity (u*) was greater than 0.35 m s−1. Empirical equations were identified that related maximal canopy conductance and daily ecosystem GPP to relative soil water content (RWC), the ratio of current soil water content to the field capacity, and to the predawn leaf water potential. Both variables showed a strong decline with soil RWC for values lower than 0.7. The sharpest decline was observed for GPP. The curves reached zero for RWC=0.41 and 0.45 for conductance and GPP, respectively. When the predawn leaf water potential was used as a surrogate for soil water potential, both variables showed a hyperbolic decline with decreasing water potential.

These results were compared with already published literature values obtained at leaf level from the same tree species. Scaling up from the leaf to ecosystem highlighted the limitation of two big‐leaf representations: Penman–Monteith and Sellers' Π factor. Neither held completely for comparing leaf and canopy fluxes. Tower measurements integrate fluxes from foliage elements clumped at several levels of organization: branch, tree, and ecosystem. The Q. ilex canopy exhibited non‐random distribution of foliage, emphasizing the need to take into account a clumping index, the factor necessary to apply the Lambert–Beer law to natural forests.

Our results showed that drought is an important determinant in water losses and CO2 fluxes in water‐limited ecosystems. In spite of the limitations inherent to the big‐leaf representation of the canopy, the equations are useful for predicting the influence of environmental factors in Mediterranean woodlands and for interpreting ecosystem exchange measurements.
Impact of soil warming and shading on colonization and community structure of arbuscular mycorrhizal fungi in roots of a native grassland community
Authors: Heinemeyer Andreas , Ridgway Karyn P. , Edwards Everard J. , Benham David G. , Young J. Peter W. , Fitter Alastair H.
Published: December 2004

Arbuscular mycorrhizal (AM) fungi have a major influence on the structure, responses and below‐ground C allocation of plant communities. Our lack of understanding of the response of AM fungi to factors such as light and temperature is an obstacle to accurate prediction of the impact of global climate change on ecosystem functioning. In order to investigate this response, we divided a grassland site into 24 plots, each either unshaded or partly shaded with soil either unheated or heated by 3°C at 2 cm depth. In both short‐term studies in spring and autumn, and in a 1‐year‐long study, we measured root length colonization (LRC) by AM and non‐AM fungi. For selected root samples, DNA sequences were amplified by PCR with fungal‐specific primers for part of the small sub‐unit (SSU) rRNA gene. In spring, the total LRC increased over 6 weeks from 12% to 25%. Shading significantly reduced AM but increased non‐AM fungal colonization, while soil warming had no effect. In the year‐long study, colonization by AM fungi peaked in summer, whereas non‐AM colonization peaked in autumn, when there was an additive effect of shading and soil warming that reduced AM but increased non‐AM fungi. Stepwise regression revealed that light received within the 7 days prior to sampling was the most significant factor in determining AM LRC and that mean temperature was the most important influence on non‐AM LRC. Loglinear analysis confirmed that there were no seasonal or treatment effects on the host plant community. Ten AM fungal sequence types were identified that clustered into two families of the Glomales, Glomaceae and Gigasporaceae. Three other sequence types were of non‐AM fungi, all Ascomycotina. AM sequence types showed seasonal variation and shading impacts: loglinear regression analysis revealed changes in the AM fungal community with time, and a reduction of one Glomus sp. under shade, which corresponded to a decrease in the abundance of Trifolium repens. We suggest that further research investigating any impacts of climate change on ecosystem functioning must not only incorporate their natural AM fungal communities but should also focus on niche separation and community dynamics of AM fungi.
Storage and sequestration potential of topsoil organic carbon in China's paddy soils
Authors: Pan Genxing , Li Lianqing , Wu Laosheng , Zhang Xuhui
Published: December 2004

Carbon (C) storage and sequestration in agricultural soils is considered to be an important issue in the study of terrestrial C cycling and global climatic change. The baseline C stock and the C sequestration potential are among the criteria for a region or a state to adopt strategies or policies in response to commitment to the Kyoto Protocol. Paddy soils represent a large portion of global cropland. However, little information on the potential of C sequestration and storage is available for such soils. In this paper, an estimation of the topsoil soil organic carbon (SOC) pool and the sequestration potential of paddy soils in China was made by using the data from the 2nd State Soil Survey carried out during 1979–1982 and from the nationwide arable soil monitoring system established since then. Results showed that the SOC density ranged from 12 to 226 t C ha−1 with an area‐weighted mean density of 44 t C ha−1, which is comparable to that of the US grasslands and is higher than that of the cultivated dryland soils in China and the US. The estimated total topsoil SOC pool is 1.3 Pg, with 0.85 Pg from the upper plow layer and 0.45 Pg from the plowpan layer. This pool size is ∼2% of China's total storage in the top 1 m of the soil profiles and ∼4% of the total topsoil pool, while the area percentage of paddy soil is 3.4% of the total land. The C pool in paddy soils was found predominantly in southeast China geographically and in the subgroups of Fe‐accumulating and Fe‐leaching paddy soils pedogenetically. In comparison with dryland cultivation, irrigation‐based rice cultivation in China has induced significant enrichment of SOC storage (0.3 Pg) in paddy soils. The induced total C sequestration equals half of China's total annual CO2 emission in the 1990s. Estimates using different SOC sequestration scenarios show that the paddy soils of China have an easily attainable SOC sequestration potential of 0.7 Pg under present conditions and may ultimately sequester 3.0 Pg. Soil monitoring data showed that the current C sequestration rate is 12 Tg yr−1. The total C sequestration potential and the current sequestration rate of the paddy soils are over 30%, while the area of the paddy soils is 26% that of China's total croplands. Therefore, practicing sustainable agriculture is urgently needed for enhancing SOC storage to realize the ultimate SOC sequestration of rice‐based agriculture of China, as the current C sequestration rate is significantly lower than the potential rate.
Estimating soil carbon fluxes following land‐cover change: a test of some critical assumptions for a region in Costa Rica
Authors: Powers Jennifer S. , Read Jane M. , Denslow Julie S. , Guzman Sandra M.
Published: December 2004

Changes in soil carbon storage that accompany land‐cover change may have significant effects on the global carbon cycle. The objective of this work was to examine how assumptions about preconversion soil C storage and the effects of land‐cover change influence estimates of regional soil C storage. We applied three models of land‐cover change effects to two maps of preconversion soil C in a 140  000 ha area of northeastern Costa Rica. One preconversion soil C map was generated using values assigned to tropical wet forest from the literature, the second used values obtained from extensive field sampling. The first model of land‐cover change effects used values that are typically applied in global assessments, the second and third models used field data but differed in how the data were aggregated (one was based on land‐cover transitions and one was based on terrain attributes). Changes in regional soil C storage were estimated for each combination of model and preconversion soil C for three time periods defined by geo‐referenced land‐cover maps.

The estimated regional soil C under forest vegetation (to 0.3 m) was higher in the map based on field data (10.03 Tg C) than in the map based on literature data (8.90 Tg C), although the range of values derived from propagating estimation errors was large (7.67–12.40 Tg C). Regional soil C storage declined through time due to forest clearing for pasture and crops. Estimated CO2 fluxes depended more on the model of land‐cover change effects than on preconversion soil C. Cumulative soil C losses (1950–1996) under the literature model of land‐cover effects exceeded estimates based on field data by factors of 3.8–8.0. In order to better constrain regional and global‐scale assessments of carbon fluxes from soils in the tropics, future research should focus on methods for extrapolating regional‐scale constraints on soil C dynamics to larger spatial and temporal scales.
Soil CO2 efflux in a boreal pine forest under atmospheric CO2 enrichment and air warming
Authors: Niinistö Sini Maaria , Silvola Jouko , Kellomäki Seppo
Published: December 2004

The response of forest soil CO2 efflux to the elevation of two climatic factors, the atmospheric concentration of CO2 (↑CO2 of 700 μmol mol−1) and air temperature (↑T with average annual increase of 5°C), and their combination (↑CO2+↑T) was investigated in a 4‐year, full‐factorial field experiment consisting of closed chambers built around 20‐year‐old Scots pines (Pinus sylvestris L.) in the boreal zone of Finland. Mean soil CO2 efflux in May–October increased with elevated CO2 by 23–37%, with elevated temperature by 27–43%, and with the combined treatment by 35–59%. Temperature elevation was a significant factor in the combined 4‐year efflux data, whereas the effect of elevated CO2 was not as evident. Elevated temperature had the most pronounced impact early and late in the season, while the influence of elevated CO2 alone was especially notable late in the season. Needle area was found to be a significant predictor of soil CO2 efflux, particularly in August, a month of high root growth, thus supporting the assumption of a close link between whole‐tree physiology and soil CO2 emissions. The decrease in the temperature sensitivity of soil CO2 efflux observed in the elevated temperature treatments in the second year nevertheless suggests the existence of soil response mechanisms that may be independent of the assimilating component of the forest ecosystem. In conclusion, elevated atmospheric CO2 and air temperature consistently increased forest soil CO2 efflux over the 4‐year period, their combined effect being additive, with no apparent interaction.
Aphid individual performance may not predict population responses to elevated CO2 or O3
Authors: Awmack Caroline S. , Harrington Richard , Lindroth Richard L.
Published: December 2004

Changes in atmospheric composition affect plant quality and herbivore performance. We used the Aspen Free Air CO2 Enrichment (FACE) facility to investigate the impacts of elevated carbon dioxide (CO2) and ozone (O3) on the performance of the aphid Cepegillettea betulaefoliae Granovsky feeding on paper birch (Betula papyrifera Marsh.). In Year 1, we simultaneously measured individual performance and population growth rates, and in Year 2 we surveyed natural aphid, predator and parasitoid populations throughout the growing season. Aphid growth and development (relative growth rate (RGR), development time, adult weight, embryo number and the birth weight of newborn nymphs) were unaffected by CO2 and O3. Aphid fecundity decreased on trees grown at elevated CO2, O3 and CO2+O3. Neither nymphal performance nor adult size were reliable indicators of future fecundity at elevated CO2 and/or O3. Aphid populations protected from natural enemies were unaffected by elevated CO2, but increased significantly at elevated O3. Individual fecundity in elevated CO2 and O3 atmospheres did not predict population growth rates, probably because of changes in the strength of intraspecific competition or the ability of the aphids to induce nutrient sinks. Natural aphid, predator and parasitoids populations (Year 2) showed few significant responses to CO2 and O3, although CO2 and O3 did affect the timing of aphid and natural enemy peak abundance. Elevated CO2 and O3 affected aphid and natural enemy populations independently: no CO2× O3 interactions were observed. We conclude that: (1) aphid individual performance did not predict population responses to CO2 and O3 and (2) elevated CO2 and O3 atmospheres are unlikely to affect C. betulaefoliae populations in the presence of natural enemy communities.
Global warming, regional trends and inshore environmental conditions influence coral bleaching in Hawaii
Authors: Jokiel Paul L. , Brown Eric K.
Published: December 2004

Hawaiian waters show a trend of increasing temperature over the past several decades that are consistent with observations in other coral reef areas of the world. The first documented large‐scale coral bleaching occurred in the Hawaii region during late summer of 1996, with a second in 2002. The bleaching events in Hawaii were triggered by a prolonged regional positive oceanic sea surface temperature (SST) anomaly greater than 1°C that developed offshore during the time of annual summer temperature maximum. High solar energy input and low winds further elevated inshore water temperature by 1–2°C in reef areas with restricted water circulation (bays, reef flats and lagoons) and in areas where mesoscale eddies often retain water masses close to shore for prolonged periods of time. Data and observations taken during these events illustrate problems in predicting the phenomena of large‐scale bleaching. Forecasts and hind‐casts of these events are based largely on offshore oceanic SST records, which are only a first approximation of inshore reef conditions. The observed oceanic warming trend is the ultimate cause of the increase in the frequency and severity of bleaching events. However, coral reefs occur in shallow inshore areas where conditions are influenced by winds, orographic cloud cover, complex bathymetry, waves and inshore currents. These factors alter local temperature, irradiance, water motion and other physical and biological variables known to influence bleaching.
Excision of pseudotumour in a patient with haemophilia A and inhibitor managed with recombinant factor VIIa
Authors: Takedani H. , Mikami S. , Kawasaki N. , Abe Y. , Arai M. , Naka H. , Yoshioka A.
Published: December 2004

Summary.  We describe a patient with haemophilia A and factor VIII inhibitor who underwent surgical excision of a large pseudotumour in the left femoral region. Haemostasis was successfully maintained with bolus doses of recombinant factor VIIa at 2‐h intervals and anti‐fibrinolytic therapy, and the pseudotumour was removed. Subsequently, the dose interval was gradually prolonged to 8 h for a total of 18 days. Although a spontaneous haemorrhage was observed on postoperative day 8, haemostasis was achieved by reducing the dosage interval. No adverse event occurred during the course of treatment.
Sunken roads as habitats for forest plant species in a dynamic agricultural landscape: effects of age and isolation
Authors: Deckers Bart , Becker Piet De , Honnay Olivier , Hermy Martin , Muys Bart
Published: December 2004

Aim  This study tests the hypothesis that linear, woody habitat patches surrounding small, sunken rural roads not only function as an unstable sink but also as a true, sustainable habitat for forest plants. Furthermore, factors affecting the presence of forest plant species in sunken roads are determined. Finally, the implications of these findings for the overall metapopulation dynamics of forest plant species in fragmented agricultural landscapes are assessed.

Location  The study area, c. 155 km2 in size, is situated in a fragmented agricultural landscape within the loamy region of central Belgium.

Methods  Forest species presence–absence data were collected for 389 sunken roads. The effect of area, depth, age and isolation on sunken road species richness was assessed using linear regression and analysis of variance (anova). Analysis of covariance was employed to study the interaction between age and isolation. Differences in plant community dispersal spectra in relation to sunken road age and isolation were analysed by means of linear regression and anova.

Results  Sunken roads proved to function as an important habitat for forest plants. The sink‐hypothesis was falsified by a clear species accumulation in time: sunken road species richness significantly increased with the age of the elements. Sunken road age mainly affected species richness through effects on both area and depth, affecting habitat quality and diversity. Furthermore, sunken road isolation had a significant impact on species richness as well, with the number of forest species decreasing with increasing isolation of the elements, indicating dispersal limitation in sunken road habitats. Moreover, a significant age × isolation interaction effect was demonstrated. Differences in regression slopes for isolation between age classes revealed that the effect of isolation intensified with increasing age of the elements. Differential colonization in relation to forest species dispersal capacities probably account for this, as confirmed by the analysis of sunken road plant community dispersal spectra, with the fraction of species with low dispersal capacities increasing with increasing age and decreasing isolation of the elements.

Main conclusions  During sunken road development, area and depth increase and, gradually, suitable habitat conditions for forest plant species arise. Depending on their ecological requirements and dispersal capacities, forest species progressively colonize these habitats as a function of the element's isolation. The functioning of sunken roads as a sustainable habitat for forest species enhances the metapopulation viability of forest plants in agricultural landscapes and has important consequences for forest restoration practices. Moreover, the results of this work call for integrating the presence of forest species in small‐scaled linear habitat patches in forest fragmentation studies.
Community structure and zonation patterns of rocky shores at high latitudes: an interocean comparison
Authors: Ingólfsson Agnar
Published: December 2004

Aim  To compare the structure of communities of sheltered rocky shores at high latitudes in widely separated regions in order to search for similarities and dissimilarities.

Locations  Three regions with similar physical environments were investigated: south‐western Iceland, southern Alaska, and the Magellanic region.

Methods  Cover of algae and sessile animals was estimated and animals were counted in quadrats laid along a number of transects in each of the three regions. Transects were divided into 10 height intervals with reference to tidal levels, and comparisons made on the basis of average distributions of species within each of 11 defined guilds.

Results  Icelandic and Alaskan shores had a number of species in common, although these were in the minority. No species was common to southern and northern regions, with the possible exception of Mytilus edulis. Most defined guilds were present in all regions, but their taxonomic composition was often radically different. The molluscan filtering guild was the guild showing greatest similarity in the three regions, while canopy‐forming algae were absent from the Magellanic region and balanid filterers were virtually absent from Iceland. Crustacean grazers were only prominent in Iceland, and molluscan grazers were more common there than in the other regions. Zonation of species was recognizable and species diversity increased seawards in all regions.

Main conclusions  Few, if any, assembly rules could be detected when comparing regions, except for the universal increase in species diversity seawards. The absence of ‘key’ species in one region may affect the distribution of other species. All major opportunities for resource exploitation are not utilized in all regions. In some instances it is possible to recognize ecological equivalents in different regions. No recurrent distinct zones are apparent when regions are compared. A universal descriptive system of zonation, such as developed by Stephenson & Stephenson (1949) and Lewis (1964), was found to be not applicable.