bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental research on the rock electrical parameter dispersion properties in the displacement process
Authors: Xiao Zhanshan , Zhang Shengwen , Zhang Tiexuan , Zhu Shihe , Ma Jing
Published: June 2009

Based on experiments on rock electrical parameter dispersion properties in both water displacing oil and oil displacing water processes, it is found that the frequency dispersion properties of electrical parameters in water‐bearing rocks are quite different from those in oil‐bearing rocks. Oil saturation can severely impact the rock electrical parameter dispersion properties and as the oil saturation increases, the properties are more distinguishing. The variation of formation water salinity has a significant effect on the rock resistivity, hence the modulus of the rock complex resistivity varies with water saturation and a U‐shaped curve occurs over a single frequency, just like the normal resistivity. However, the effect of formation water salinity on the rock frequency dispersion is less than that of oil saturation. As a result, the rock electrical parameter dispersion properties will have a significant potential of application in the evaluation of watered‐out zones as well as identification of oil‐bearing zones and water‐bearing zones.
Fast velocity analysis by wave path migration
Authors: Liu Yike , Sun Hongchuan , Chang Xu
Published: June 2009

Iterative migration velocity analysis is computationally expensive, where most of the computation time is used for generating prestack depth images. By using a reduced form of Kirchhoff migration, denoted as wave path migration, we can significantly speed up the depth imaging process and reduce the entire velocity analysis expense accordingly. Our results with 2D synthetic and field data show that wave path migration velocity analysis can efficiently improve the velocity model and the wave path migration velocity analysis updated velocity correlates well with that from the Kirchhoff migration velocity analysis. The central processing unit comparison shows that, for a 2D synthetic and field data set, wave path migration velocity analysis is six times faster than Kirchhoff migration velocity analysis. This efficiency should be even greater for 3D data.
Traveltime approximations for q‐P waves in vertical transversely isotropy media*
Authors: Aleixo Rafael , Schleicher Jörg
Published: June 2009

As exploration targets have become deeper, cable lengths have increased accordingly, making the conventional two term hyperbolic traveltime approximation produce increasingly erroneous traveltimes. To overcome this problem, many traveltime formulas were proposed in the literature that provide approximations of different quality. In this paper, we concentrate on simple traveltime approximations that depend on a single anisotropy parameter. We give an overview of a collection of such traveltime approximations found in the literature and compare their quality. Moreover, we propose some new single‐parameter traveltime approximations based on the approximations found in the literature. The main advantage of our approximations is that some of them are rather simple analytic expressions that make them easy to use, while achieving the same quality as the better of the established formulas.
Magnetic basement: gravity‐guided magnetic source depth analysis and interpretation
Authors: Goussev Serguei A. , Peirce John W.
Published: June 2009

We present a new integrated approach to the interpretation of magnetic basement that is based on recognition of characteristic patterns in distributions and alignments of magnetic source depth solutions above and below the surface of magnetic basement. This approach integrates a quantitative analysis of depth solutions, obtained by 2D Werner deconvolution of the magnetic data, with a qualitative evaluation of the Bouguer gravity anomalies. The crystalline/metamorphic basement and sedimentary cover have different origins, tectonic histories, lithologies and magnetic properties. These differences result in different geometries of magnetic sources associated with faults, fracture zones, igneous intrusions, erosional truncations, subcrop edges and other structural discontinuities.

Properly tuned, 2D Werner deconvolution is able to resolve the intra‐sedimentary and intra‐basement magnetic source geometries into distinctly different distributions and alignments of calculated depth solutions. An empirical set of criteria, basement indicators, was developed for identification and correlation of the basement surface. The ambiguity of basement correlation with limited or non‐existent well control, which is common for onshore frontier and offshore explorations, can be reduced by incorporating the Bouguer gravity data into the process of correlation.
Growth, carbon‐isotope discrimination, and drought‐associated mortality across a Pinus ponderosa elevational transect
Authors: McDOWELL NATE G. , ALLEN CRAIG D. , MARSHALL LAURA
Published: June 2009

Drought‐ and insect‐associated tree mortality at low‐elevation ecotones is a widespread phenomenon but the underlying mechanisms are uncertain. Enhanced growth sensitivity to climate is widely observed among trees that die, indicating that a predisposing physiological mechanism(s) underlies tree mortality. We tested three, linked hypotheses regarding mortality using a ponderosa pine (Pinus ponderosa) elevation transect that experienced low‐elevation mortality following prolonged drought. The hypotheses were: (1) mortality was associated with greater growth sensitivity to climate, (2) mortality was associated with greater sensitivity of gas exchange to climate, and (3) growth and gas exchange were correlated. Support for all three hypotheses would indicate that mortality results at least in part from gas exchange constraints. We assessed growth using basal area increment normalized by tree basal area [basal area increment (BAI)/basal area (BA)] to account for differences in tree size. Whole‐crown gas exchange was indexed via estimates of the CO2 partial pressure difference between leaf and atmosphere (pa−pc) derived from tree ring carbon isotope ratios (δ13C), corrected for temporal trends in atmospheric CO2 and δ13C and elevation trends in pressure. Trees that survived the drought exhibited strong correlations among and between BAI, BAI/BA, pa−pc, and climate. In contrast, trees that died exhibited greater growth sensitivity to climate than trees that survived, no sensitivity of pa−pc to climate, and a steep relationship between pa−pc and BAI/BA. The pa−pc results are consistent with predictions from a theoretical hydraulic model, suggesting trees that died had a limited buffer between mean water availability during their lifespan and water availability during drought – i.e., chronic water stress. It appears that chronic water stress predisposed low‐elevation trees to mortality during drought via constrained gas exchange. Continued intensification of drought in mid‐latitude regions may drive increased mortality and ecotone shifts in temperate forests and woodlands.
Large‐scale redistribution of maximum fisheries catch potential in the global ocean under climate change
Authors: CHEUNG WILLIAM W. L. , LAM VICKY W. Y. , SARMIENTO JORGE L. , KEARNEY KELLY , WATSON REG , ZELLER DIRK , PAULY DANIEL
Published: June 2009

Previous projection of climate change impacts on global food supply focuses solely on production from terrestrial biomes, ignoring the large contribution of animal protein from marine capture fisheries. Here, we project changes in global catch potential for 1066 species of exploited marine fish and invertebrates from 2005 to 2055 under climate change scenarios. We show that climate change may lead to large‐scale redistribution of global catch potential, with an average of 30–70% increase in high‐latitude regions and a drop of up to 40% in the tropics. Moreover, maximum catch potential declines considerably in the southward margins of semienclosed seas while it increases in poleward tips of continental shelf margins. Such changes are most apparent in the Pacific Ocean. Among the 20 most important fishing Exclusive Economic Zone (EEZ) regions in terms of their total landings, EEZ regions with the highest increase in catch potential by 2055 include Norway, Greenland, the United States (Alaska) and Russia (Asia). On the contrary, EEZ regions with the biggest loss in maximum catch potential include Indonesia, the United States (excluding Alaska and Hawaii), Chile and China. Many highly impacted regions, particularly those in the tropics, are socioeconomically vulnerable to these changes. Thus, our results indicate the need to develop adaptation policy that could minimize climate change impacts through fisheries. The study also provides information that may be useful to evaluate fisheries management options under climate change.
Implications of future climate and atmospheric CO2 content for regional biogeochemistry, biogeography and ecosystem services across East Africa
Authors: DOHERTY RUTH M. , SITCH STEPHEN , SMITH BENJAMIN , LEWIS SIMON L. , THORNTON PHILIP K.
Published: June 2009

We model future changes in land biogeochemistry and biogeography across East Africa. East Africa is one of few tropical regions where general circulation model (GCM) future climate projections exhibit a robust response of strong future warming and general annual‐mean rainfall increases. Eighteen future climate projections from nine GCMs participating in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment were used as input to the LPJ dynamic global vegetation model (DGVM), which predicted vegetation patterns and carbon storage in agreement with satellite observations and forest inventory data under the present‐day climate. All simulations showed future increases in tropical woody vegetation over the region at the expense of grasslands. Regional increases in net primary productivity (NPP) (18–36%) and total carbon storage (3–13%) by 2080–2099 compared with the present‐day were common to all simulations. Despite decreases in soil carbon after 2050, seven out of nine simulations continued to show an annual net land carbon sink in the final decades of the 21st century because vegetation biomass continued to increase. The seasonal cycles of rainfall and soil moisture show future increases in wet season rainfall across the GCMs with generally little change in dry season rainfall. Based on the simulated present‐day climate and its future trends, the GCMs can be grouped into four broad categories. Overall, our model results suggest that East Africa, a populous and economically poor region, is likely to experience some ecosystem service benefits through increased precipitation, river runoff and fresh water availability. Resulting enhancements in NPP may lead to improved crop yields in some areas. Our results stand in partial contradiction to other studies that suggest possible negative consequences for agriculture, biodiversity and other ecosystem services caused by temperature increases.
The seasonal sensitivity of Cyanobacteria and other phytoplankton to changes in flushing rate and water temperature
Authors: ELLIOTT J. ALEX
Published: June 2009

The phytoplankton lake community model PROTECH (Phytoplankton RespOnses To Environmental CHange) was applied to the eutrophic lake, Esthwaite Water (United Kingdom). It was validated against monitoring data from 2003 and simulated well the seasonal pattern of total chlorophyll, diatom chlorophyll and Cyanobacteria chlorophyll with respective R2‐values calculated between observed and simulated of 0.68, 0.72 and 0.77 (all P<0.01). This simulation was then rerun through various combinations of factorized changes covering a range of half to double the flushing rate and from −1 to +4 °C changes in water temperature. Their effect on the phytoplankton was measured as annual, spring, summer and autumn means of the total and species chlorophyll concentrations. In addition, Cyanobacteria mean percentage abundance (%Cb) and maximum percentage abundance (Max %Cb) was recorded, as were the number of days that Cyanobacteria chlorophyll concentration exceed two World Health Organization (WHO) derived risk thresholds (10 and 50 mg m−3). The phytoplankton community was dominated in the year by three of the eight phytoplankton simulated. The vernal bloom of the diatom Asterionella showed little annual or seasonal response to the changing drivers but this was not the case for the two Cyanobacteria that also dominated, Anabaena and Aphanizomenon. These Cyanobacteria showed enhanced abundance, community dominance and increased duration above the highest WHO risk threshold with increasing water temperature and decreasing flushing rate: this effect was greatest in the summer period. However, the response was ultimately controlled by the availability of nutrients, particularly phosphorus and nitrogen, with occasional declines in the latter's concentration helping the dominance of these nitrogen‐fixing phytoplankton.
Nitrogen‐dependent recovery of subarctic tundra vegetation after simulation of extreme winter warming damage to Empetrum hermaphroditum
Authors: AERTS RIEN
Published: June 2009

Vast areas of (sub)arctic tundra are dominated by the ericoid dwarf shrub Empetrum hermaphroditum. Recent experimental and observational data have shown that Empetrum can be damaged heavily by recurrent extreme winter warming. In addition, summer warming leads to increased soil N availability in tundra ecosystems. In a 7‐year experiment, I investigated the recovery of subarctic Empetrum‐dominated tundra vegetation using a factorial combination of various degrees of aboveground Empetrum removal (simulating the damaging effects of extreme winter warming) and N addition (simulating one of the effects of summer warming). After 7 years no new species had established in the plots. The growth of planted Betula nana seedlings was stimulated by Empetrum removal and reduced by N addition. This Empetrum‐dominated tundra ecosystem was resilient against severe disturbances. Only when Empetrum was 100% removed did it fail to recover, and only in combination with high N supply the subordinate species (notably Eriophorum vaginatum and Rubus chamaemorus, a graminoid and a forb) could benefit. In the 50% removal treatment Empetrum recovered in 7 years when no N was supplied and the cover of the subordinate species did not change. However, when N was added Empetrum recovered faster (in 4 years) and the subordinates decreased. When Empetrum was not removed and N was added, Empetrum even increased in abundance at the expense of the subordinate species. Thus, profound changes in tundra ecosystems can only be expected when Empetrum is very heavily damaged as a result of recurrent extreme winter warming and when soil N availability is increased as a result of summer warming. These changes in species composition upon extreme disturbance events may lead to a wide variety of ecosystem feedbacks and cascade processes as this tundra system is relatively species‐poor, and can be hypothesized to have low functional redundancy.
Uncertainty in ensemble forecasting of species distribution
Authors: BUISSON LAËTITIA , THUILLER WILFRIED , CASAJUS NICOLAS , LEK SOVAN , GRENOUILLET GAËL
Published: June 2009

Species distribution modelling has been widely applied in order to assess the potential impacts of climate change on biodiversity. Many methodological decisions, taken during the modelling process and forecasts, may, however, lead to a large variability in the assessment of future impacts. Using measures of species range change and turnover, the potential impacts of climate change on French stream fish species and assemblages were evaluated. Our main focus was to quantify the uncertainty in the projections of these impacts arising from four sources of uncertainty: initial datasets (Data), statistical methods [species distribution models (SDM)], general circulation models (GCM), and gas emission scenarios (GES). Several modalities of the aforementioned uncertainty sources were combined in an ensemble forecasting framework resulting in 8400 different projections. The variance explained by each source was then extracted from this whole ensemble of projections. Overall, SDM contributed to the largest variation in projections, followed by GCM, whose contribution increased over time equalling almost the proportion of variance explained by SDM in 2080. Data and GES had little influence on the variability in projections. Future projections of range change were more consistent for species with a large geographical extent (i.e., distribution along latitudinal or stream gradients) or with restricted environmental requirements (i.e., small thermal or elevation ranges). Variability in projections of turnover was spatially structured at the scale of France, indicating that certain particular geographical areas should be considered with care when projecting the potential impacts of climate change. The results of this study, therefore, emphasized that particular attention should be paid to the use of predictions ensembles resulting from the application of several statistical methods and climate models. Moreover, forecasted impacts of climate change should always be provided with an assessment of their uncertainty, so that management and conservation decisions can be taken in the full knowledge of their reliability.
Greater seed production in elevated CO2is not accompanied by reduced seed quality inPinus taedaL.
Authors: WAY DANIELLE A. , LADEAU SHANNON L. , MCCARTHY HEATHER R. , CLARK JAMES S. , OREN RAM , FINZI ADRIEN C. , JACKSON ROBERT B.
Published: June 2009

For herbaceous species, elevated CO2often increases seed production but usually leads to decreased seed quality. However, the effects of increased atmospheric CO2on tree fecundity remain uncertain, despite the importance of reproduction to the composition of future forests. We determined how seed quantity and quality differed for pine trees grown for 12 years in ambient and elevated (ambient+200 μL L−1) CO2, at the Duke Forest free‐air CO2enrichment (FACE) site. We also compared annual reproductive effort with yearly measurements of aboveground net primary productivity (ANPP), precipitation (P), potential evapotranspiration (PET) and water availability [precipitation minus potential evapotranspiration (P−PET)] to investigate factors that may drive interannual variation in seed production. The number of mature, viable seeds doubled per unit basal area in high‐CO2plots from 1997 to 2008 (P<0.001), but there was no CO2effect on mean seed mass, viability, or nutrient content. Interannual variation in seed production was positively related to ANPP, with a similar percentage of ANPP diverted to reproduction across years. Seed production was negatively related to PET (P<0.005) and positively correlated with water availability (P<0.05), but showed no relationship with precipitation (P=0.88). This study adds to the few findings that, unlike herbaceous crops, woody plants may benefit from future atmospheric CO2by producing larger numbers of seeds without suffering degraded seed quality. Differential reproductive responses between functional groups and species could facilitate woody invasions or lead to changes in forest community composition as CO2rises.
Spatial patterns of climatic changes in the Eurasian north reflected in Siberian larch tree‐ring parameters and stable isotopes
Authors: SIDOROVA OLGA V. , SIEGWOLF ROLF T. W. , SAURER MATTHIAS , NAURZBAEV MUKHTAR M. , SHASHKIN ALEXANDER V. , VAGANOV EUGENE A.
Published: June 2009

A spatial description of climatic changes along circumpolar regions is presented based on larch tree‐ring width (TRW) index, latewood density (MXD), δ13C, δ18O of whole wood and cellulose chronologies from eastern Taimyr (TAY) and north‐eastern Yakutia (YAK), Russia, for the period 1900–2006, in comparison with a δ13C cellulose chronology from Finland (FIN) and a δ18O ice core record from Greenland (GISP2). Correlation analysis showed a strong positive relationships between TRW, MXD, stable isotope chronologies and June, July air temperatures for TAY and YAK, while the precipitation signal was reflected differently in tree‐ring parameters and stable isotope data for the studied sites. Negative correlations were found between July, August precipitation from TAY and stable isotopes and MXD, while May, July precipitations are reflected in MXD and stable isotopes for the YAK. No significant relationships were found between TRW and precipitation for TAY and YAK. The areas of significant correlations between July gridded temperatures and TRW, MXD and stable isotopes show widespread dimension from east to west for YAK and from north to south for TAY. The climate signal is stronger expressed in whole wood than in cellulose for both Siberian regions. The comparison analysis between δ13C cellulose chronologies from FIN and TAY revealed a similar declining trend over recent decades, which could be explained by the physiological effect of the increasing atmospheric CO2. TRW, MXD and δ13C chronologies from TAY and YAK show a negative correlation with North Atlantic Oscillation index, while the δ18O chronologies show positive correlations, confirming recent warming trend at high latitudes. The strong correlation between GISP2 and δ18O of cellulose from YAK chronologies reflects the large‐scale climatic signal connected by atmospheric circulation patterns expressed by precipitation.
Risk of predation enhances the lethal effects of UV‐B in amphibians
Authors: ALTON LESLEY A. , WILSON ROBBIE S. , FRANKLIN CRAIG E.
Published: June 2009

Amphibian declines are a prominent part of the global biodiversity crisis and have received special consideration because they have occurred relatively recently, on a global scale, and in seemingly pristine habitats where no obvious anthropogenic cause is apparent. Although several causes for declines have been implicated, the isolation of a singular cause has proven elusive. Consequently, it has been hypothesized that complex interactions between multiple environmental stressors, particularly those associated with global change, may be responsible. Increasing ultraviolet‐B radiation (UV‐B) associated with stratospheric ozone depletion is one such stressor that has received considerable attention. UV‐B causes enhanced lethal effects when combined with other factors such as aquatic pH, contaminants, temperature and pathogens, but little is known of how UV‐B interacts with pervasive biological stressors, such as risk of predation. We exposed Limnodynastes peronii tadpoles to UV‐B and predatory chemical cues in a controlled laboratory experiment to determine their independent and interactive effects on survival and morphology. We show that UV‐B and risk of predation interact synergistically to enhance mortality above the additive effects of the independent stressors, and that exposure to UV‐B affects the ability of tadpoles to morphologically respond to predatory chemical cues (i.e. predator‐induced phenotypic plasticity), which has implications for their survival in an environment with predators. This highlights the importance of considering both anthropogenic and naturally occurring stressors when examining the underlying causes of amphibian declines.
Global climate change and litter decomposition: more frequent fire slows decomposition and increases the functional importance of invertebrates
Authors: BRENNAN KARL E. C. , CHRISTIE FIONA J. , YORK ALAN
Published: June 2009

Of the many mechanisms by which global climate change may alter ecosystem processes perhaps the least known and insidious is altered disturbance regimes. We used a field‐based experiment to examine the climate change scenario of more frequent fires with altered invertebrate assemblages on the decomposition ofEucalyptusleaves. Our design comprised three fire regimes [long‐term fire exclusion (FE), long‐term frequent burning (FB) and FE altered to FB (FEFB)] and two litter bag mesh sizes (8.0 and 0.2 mm) that either permitted or denied access to the leaf litter by most invertebrates. We found a significant interaction effect between fire regime and mesh size in losses of litter mass and net carbon (C). Compared with the regime of FE, with more frequent burning (FB and FEFB) the pace of decomposition was slowed by 41% (when access to litter by most invertebrates is not impeded). For the regime of FE, denying access to leaf litter by most invertebrates did not alter the pace of decomposition. Conversely, under regimes of frequently burning, restricting access to the litter by most invertebrates altered the pace of decomposition by 46%. Similar results were found for net C. For net losses of nitrogen (N), no interaction effects between fire regime and mesh size were detected, although both main effects were significant. Our results show that by modifying disturbance regimes such as fire frequency, global climate change has the potential to modify the mechanism by which ecosystems function. With more FB, decomposition is driven not only by fire regime induced changes in substrate quality and/or physiochemical conditions but through the interaction of disturbance regime with animal assemblages mediating ecosystem processes.
Antiphospholipid antibodies in haemophilia patients with severe bleeding tendency: cause, consequence or a consequential cause?
Authors: SHETTY S. , VORA S. , KULKARNI B. , MOTA L. , GHOSH K.
Published: June 2009

Summary.  The prevalence, cause and the impact of antiphospholipid antibodies (APAs) on the clinical severity in haemophilia patients is poorly studied. We studied 72 severe seronegative (negative for HIV, HBsAg, HCV) haemophilia patients for the presence of four common APAs. Twenty‐six (36.1%) were positive for any one of the APAs studied of which eight were positive only for anticardiolipin antibodies, three for β2 glycoprotein (β2GP1), four for prothrombin (PT) and six for anti annexin antibodies. Remaining six patients showed multi‐specific antibodies. Further, clinically severe haemophilia patients (n = 37) showed higher prevalence of APAs as compared with the clinically milder group (n = 35) suggesting that these antibodies do not contribute in alleviating the clinical severity in haemophilia patients as has been observed with other inherited thrombophilia markers. The study of in vitro thrombin generation showed a higher endogenous thrombin potential (ETP) i.e. almost normal, in case of β2GP1‐positive patients as compared with patients with other types of APAs. High prevalence of APAs in clinically severe haemophilia patients may be a consequence of continuing tissue damage in the clinically severe group; as in India, clotting factor concentrates cannot be used ad lib because of financial constraints. Higher thrombin‐generating potential in case of patients positive for β2GP1 did not seem to have any impact on the clinical severity of haemophilia patients.
Plasma cell toll‐like receptor (TLR) expression differs from that of B cells, and plasma cell TLR triggering enhances immunoglobulin production
Authors: Dorner Marcus , Brandt Simone , Tinguely Marianne , Zucol Franziska , Bourquin Jean‐Pierre , Zauner Ludwig , Berger Christoph , Bernasconi Michele , Speck Roberto F. , Nadal David
Published: June 2009

Toll‐like receptors (TLRs) are key receptors of the innate immune system and show cell subset‐specific expression. We investigated the messenger RNA (mRNA) expression of TLR genes in human haematopoietic stem cells (HSC), in naïve B cells, in memory B cells, in plasma cells from palatine tonsils and in plasma cells from peripheral blood. HSC and plasma cells showed unrestricted expression of TLR1–TLR9, in contrast to B cells which lacked TLR3, TLR4 and TLR8 but expressed mRNA of all other TLRs. We demonstrated, for the first time, that TLR triggering of terminally differentiated plasma cells augments immunoglobulin production. Thus, boosting the immediate antibody response by plasma cells upon pathogen recognition may point to a novel role of TLRs.
Toll‐like receptor 4 signalling through MyD88 is essential to control Salmonella enterica serovar Typhimurium infection, but not for the initiation of bacterial clearance
Authors: Talbot Suzanne , Tötemeyer Sabine , Yamamoto Masahiro , Akira Shizuo , Hughes Katherine , Gray David , Barr Tom , Mastroeni Pietro , Maskell Duncan J. , Bryant Clare E.
Published: June 2009

Toll‐like receptor‐4 (TLR4) is important in protection against lethal Salmonella enterica serovar Typhimurium (S. Typhimurium) infection. Control of the early stages of sublethal S. Typhimurium infection in mice depends on TLR4‐dependent activation of macrophages and natural killer (NK) cells to drive an inflammatory response. TLR4 signals through the adapter proteins Mal/MyD88 and TRIF‐related adaptor molecule (TRAM)/TIR‐domain‐containing adaptor‐inducing interferon‐b (TRIF). In the mouse typhoid model we showed that TLR4 and MyD88, but not Mal or TRIF, are essential for the control of exponential S. Typhimurium growth. TRIF−/− mice have a higher bacterial load in comparison with wild‐type mice during a sublethal infection because TRIF is important for bacterial killing during the first day of systemic disease. Minimal pro‐inflammatory responses were induced by S. Typhimurium infection of macrophages from TLR4−/−, MyD88−/− and TRIF−/− mice in vitro. Pro‐inflammatory responses from Mal−/− macrophages were similar to those from wild‐type cells. The pro‐inflammatory responses of TRIF−/− macrophages were partially restored by the addition of interferon‐γ (IFN‐γ), and TRIF−/− mice produced markedly enhanced IFN‐γ levels, in comparison to wild‐type mice, probably explaining why bacterial growth can be controlled in these mice. TLR4−/−, MyD88−/−, TRIF−/− and Mal−/− mice all initiated clearance of S. Typhimurium, suggesting that TLR4 signalling is not important in driving bacterial clearance in comparison to its critical role in controlling early bacterial growth in mouse typhoid.
Retracted: Dissociated expression of natural killer 1.1 and T‐cell receptor by invariant natural killer T cells after interleukin‐12 receptor and T‐cell receptor signalling
Authors: Emoto Masashi , Shimizu Takamitsu , Koike Hiromi , Yoshizawa Izumi , Hurwitz Robert , Kaufmann Stefan H. E. , Emoto Yoshiko
Published: June 2009

Invariant (i) natural killer T (NKT) cells become undetectable after stimulation with α‐galactosylceramide (α‐GalCer) or interleukin (IL)‐12. Although down‐modulation of surface T‐cell receptor (TCR)/NKR‐P1C (NK1.1) expression has been shown convincingly after stimulation with α‐GalCer, it is unclear whether this also holds true for IL‐12 stimulation. To determine whether failure to detect iNKT cells after IL‐12 stimulation is caused by dissociation/internalization of TCR and/or NKR‐P1C, or by block of de novo synthesis of these molecules, and to examine the role of IL‐12 in the disappearance of iNKT cells after stimulation with α‐GalCer, surface (s)/cytoplasmic (c) protein expression, as well as messenger RNA (mRNA) expression of TCR/NKR‐P1C by iNKT cells after stimulation with α‐GalCer or IL‐12, and the influence of IL‐12 neutralization on the down‐modulation of sTCR/sNKR‐P1C expression by iNKT cells after stimulation with α‐GalCer were examined. The s/cTCR+ s/cNKR‐P1C+ iNKT cells became undetectable after in vivo administration of α‐GalCer, which was partially prevented by IL‐12 neutralization. Whereas s/cNKR‐P1C+ iNKT cells became undetectable after in vivo administration of IL‐12, s/cTCR+ iNKT cells were only marginally affected. mRNA expression of TCR/NKR‐P1C remained unaffected by α‐GalCer or IL‐12 treatment, despite the down‐modulation of cTCR and/or cNKR‐P1C protein expression. By contrast, cTCR+ cNKR‐P1C+ sTCR− sNKR‐P1C− iNKT cells and cNKR‐P1C+ sNKR‐P1C− iNKT cells were detectable after in vitro stimulation with α‐GalCer and IL‐12, respectively. Our results indicate that TCR and NKR‐P1C expression by iNKT cells is differentially regulated by signalling through TCR and IL‐12R. They also suggest that IL‐12 participates, in part, in the disappearance of iNKT cells after stimulation with α‐GalCer by down‐modulating not only sNKR‐P1C, but also sTCR.
Effect of damping properties on fracture resistance of root filled premolar teeth: a dynamic finite element analysis
Authors: Ou K‐L. , Chang C‐C. , Chang W‐J. , Lin C‐T. , Chang K‐J. , Huang H‐M
Published: June 2009

Aim  To evaluate the ex vivo effects of damping on stress concentration in root filled premolar teeth.

Methodology  Damping ratios of maxillary premolar teeth that had undergone root canal treatment were tested in a laboratory model. In addition, two‐dimensional finite element (FE) models were established for dynamic analysis.

Results  The mean‐damping ratio was significantly lower in premolar teeth that had undergone root canal preparation (8.50 ± 0.53%) than in unprepared teeth (14.42 ± 2.17%) (P < 0.05). However, root filling had a significant positive effect on the damping ratio of the tooth (10.84 ± 1.70%) (P < 0.05). When the damping ratio was taken into consideration, FE analysis revealed that peak stresses in the apical one‐third of the root on the buccal side were reduced by 31.8% when mastication forces were applied on the palatal cusp and occlusal fossa.

Conclusion  Pulp tissue plays an important role in providing protective effects when teeth are subjected to a dynamic load. However, root filled teeth do not provide such protective effects.
Root and canal morphology of mandibular first and second molar teeth in a Jordanian population
Authors: Al‐Qudah A. A. , Awawdeh L. A.
Published: June 2009

Aim  To examine the root and canal morphology of mandibular permanent first and second molar teeth in a Jordanian population.

Methodology  A total of 685 extracted mandibular first and second permanent molar teeth were collected from dental clinics within north Jordan. The teeth were examined visually and the root number and morphology were recorded. After that, access cavities were prepared, pulp tissue dissolved by sodium hypochlorite and the root canals injected with Indian ink. Stained teeth were decalcified with 10% nitric acid, dehydrated with ascending concentrations of alcohol and rendered clear by immersion in methyl salicylate. The following observations were evaluated: (i) number of canals per root; (ii) number of root canals per tooth; (iii) canal configuration in each root; (iv) number and location of lateral canals and (v) presence of intercanal communications.

Results  Of 330 mandibular first molars, the majority had three (48%) or four (46%) canals, whilst 4% had a third disto‐lingual root. Of 355 mandibular second molars, 58% had three canals, 19% two and 17% had four canals, whilst 10% had C‐shaped roots. The most prevalent canal configuration in the mesial root of both first (53%) and second (40%) molars was type IV, and in distal roots was type I (54% in first and 79% in second molars).

Conclusions  Jordanian mandibular first and second molar teeth exhibit features close to the average Caucasian root and canal morphology.
A radiographic assessment of the prevalence of pulp stones in a group of Turkish dental patients
Authors: Gulsahi A. , Cebeci A. I. , Özden S.
Published: June 2009

Aim  To determine the prevalence of pulp stones in a group of patients using radiographs, and to assess any associations with age, gender, systemic diseases, tooth type, jaw, caries, restorations, impacted third molars and dental anomalies including dens invaginatus, taurodontism, dens evaginatus and microdontia.

Methodology  A total of 519 patients were selected randomly amongst patients referred to Oral Diagnosis and Radiology Department, Faculty of Dentistry, Ankara University. After clinical inspection, full‐mouth periapical radiographs were obtained. An oral radiologist examined the radiographs to identify pulp stones. Frequency distribution of teeth with pulp stones was calculated and statistical analysis was performed with chi‐square test.

Results  Of the patients, 313 (60%) were female and 206 (40%) were male. Sixty (12%) had one or more teeth that contained pulp stones. Amongst the 13 474 teeth examined radiographically, 627 (5%) had pulp stones. There was no significant association between pulp stone occurrence and gender or systemic diseases. As age increased, the prevalence of pulp stones increased (P < 0.01). Molars had statistically more pulp stones than premolars and incisors (P < 0.001). Frequencies in both maxillary and mandibular jaw were similar. There was no association between pulp stones and impacted third molars, caries, restorations or dental anomalies.

Conclusions  The prevalence of pulp stones increased with age and was significantly higher in molar teeth than premolars and incisors. There was no significant association between pulp stones and gender, systemic diseases, impacted third molars, condition of the crown and dental anomalies.
Viability of human fibroblasts in coconut water as a storage medium
Authors: Moreira‐Neto J. J. S. , Gondim J. O. , Raddi M. S. G. , Pansani C. A.
Published: June 2009

Aim  To evaluate the effectiveness of a new storage medium for avulsed teeth, coconut water, in maintaining the viability of human fibroblasts.

Methodology  Cell viability after different time periods was evaluated in the following storage media: coconut water, coconut water with sodium bicarbonate, milk, saline and still mineral water. Human fibroblasts were seeded in Eagle’s minimal essential medium (EMEM) supplemented with 7.5% foetal calf serum. After trypsinisation, 100 μL of culture medium containing approximately 104 cells mL−1 were collected and pipetted into the wells of 96‐well plates, which were incubated overnight in 5% CO2 and 95% air mixture at 37 °C. EMEM was then replaced by the storage media and the plates were incubated at 37 °C for 1, 2 and 4 h. Cell viability was determined using the neutral red assay. The proportions of viable cells after exposure to the storage media were analysed statistically by anova and the least significant difference (LSD) test (α = 5%).

Results  Milk had the greatest capacity to maintain cell viability (P < 0.05), followed by coconut water with sodium bicarbonate and saline. Coconut water was significantly worse at maintaining cell viability compared to milk, coconut water with sodium bicarbonate and saline. The smallest number of viable cells was observed for mineral water (P < 0.05).

Conclusion  Coconut water was worse than milk in maintaining human fibroblast cell viability.
Microflora in teeth associated with apical periodontitis: a methodological observational study comparing two protocols and three microscopy techniques
Authors: Richardson N. , Mordan N. J. , Figueiredo J. A. P. , Ng Y‐L. , Gulabivala K.
Published: June 2009

Aim  The aim of this study was to compare two protocols to examine bacterial colonization in teeth associated with chronic apical periodontitis with acute episodes (ap), using light microscopy (LM), transmission electron microscopy (TEM) and scanning electron microscopy (SEM).

Methodology  Nine root samples (seven teeth) were processed using either Eastman Dental Institute (EDI) (n = 4 teeth/4 roots) or Zurich (n = 3 teeth/5 roots) protocols. The roots were sectioned longitudinally; one root portion was viewed with SEM, descriptively dividing its length into apical, middle and coronal; semi‐thin and ultra‐thin transverse sections were viewed under LM and TEM from each third of the other root portion. Each root was therefore examined using all microscopy techniques. Observations of bacterial presence, description and distribution within the root canal lumen and root dentine were systematically recorded using pre‐determined criteria.

Results  The Zurich technique gave a more predictable division of the root, but the surface was slightly smeared and demineralization was incomplete. The Eastman Dental Institute (EDI) approach appeared to provide better ultrastructural detail. Bacteria were detected in eight of the nine roots. Bacterial biofilms were commonly seen adhering to the root canal surface, containing various cellular morphotypes: rods, cocci, filaments and spirochaetes. Bacteria were more evident apically than coronally, associated with the canal wall but were more commonly evident coronally than apically within the dentinal tubules. Polymorphs (PMNs) were found in all the root thirds, especially apically, often numerous and walling off the bacterial biofilm from the remaining canal lumen.

Conclusions  Both protocols had merits and de‐merits. The combination of microscopy techniques offered complementary views of intra‐radicular bacterial colonization. The perception of confinement of the host/microbial interface at the apical foramen is not entirely correct; PMNs may be found even in the coronal third of root canals containing necrotic pulp tissue.
Maternal investment in relation to sex ratio and offspring number in a small mammal – a case for Trivers and Willard theory?
Authors: Koskela Esa , Mappes Tapio , Niskanen Tuuli , Rutkowska Joanna
Published: June 2009

1.  Optimal parental sex allocation depends on the balance between the costs of investing into sons vs. daughters and the benefits calculated as fitness returns. The outcome of this equation varies with the life history of the species, as well as the state of the individual and the quality of the environment.

2.
 We studied maternal allocation and subsequent fecundity costs of bank voles, Myodes glareolus, by manipulating both the postnatal sex ratio (all‐male/all‐female litters) and the quality of rearing environment (through manipulation of litter size by −2/+2 pups) of their offspring in a laboratory setting.

3.  We found that mothers clearly biased their allocation to female rather than male offspring regardless of their own body condition. Male pups had a significantly lower growth rate than female pups, so that at weaning, males from enlarged litters were the smallest. Mothers produced more milk for female litters and also defended them more intensively than male offspring.

4.  The results agree with the predictions based on the bank vole life history: there will be selection for greater investment in daughters rather than sons, as a larger size seems to be more influencial for female reproductive success in this species. Our finding could be a general rule in highly polygynous, but weakly dimorphic small mammals where females are territorial.

5.  The results disagree with the narrow sense Trivers & Willard hypothesis, which states that in polygynous mammals that show higher variation in male than in female reproductive success, high‐quality mothers are expected to invest more in sons than in daughters.
Variation of adult survival drives population dynamics in a migrating forest bat
Authors: Schorcht Wigbert , Bontadina Fabio , Schaub Michael
Published: June 2009

1.  Variation of survival across time, between sex and ages strongly affect the population dynamics of long‐lived species. Bats are extremely long‐lived, but the variation of their survival probabilities is poorly studied with reliable methods.

2.
 We studied annual local survival probabilities of the migratory Leisler’s bats Nyctalus leisleri based on capture–recapture data from 1119 individuals sampled in bat boxes over 20 years in eastern Germany. We assessed variation in survival between sex and age classes, estimated the temporal variance of survival and tested whether survival was affected by weather during hibernation or pregnancy.

3.  Among females, our analyses revealed two groups of individuals present with different roosting occupancy, survival and/or dispersal. Local survival of locally born females increased with age [first year: 0·45 ± 0·04 (SE); later: 0·76 ± 0·04] and the high recapture probabilities indicate regular presence in the roosts. Recapture probabilities and local survival of foreign adult females were significantly lower, indicating less frequent presence in the roosts and stronger dispersal from the study area.

4.  In adult males, locally born and foreign individuals were nearly identical regarding survival and recapture, indicating a more homogenous group. Local survival was very low in the first year (0·04 ± 0·08), most likely caused by strong natal dispersal. It further increased with age (second year: 0·55 ± 0·20, later: 0·69 ± 0·07).

5.  Survival probabilities of all females varied significantly and in parallel across time, suggesting that a common environmental factor was operating which affected all individuals similarly. Spring temperature and winter North Atlantic Oscillation explained maximally 9% each of the variation in first year and adult female survival. In contrast to our expectations, the temporal variance of first‐year survival was lower than that of adult survival.

6.  We found evidence of a complicated social population structure of female Leisler’s bats. Our analyses suggest that their population dynamics are driven to a large amount by variation of survival, in particular by adult survival. The reason for the major temporal variations remains to be identified.
Pulsed resources and climate‐induced variation in the reproductive traits of wild boar under high hunting pressure
Authors: Sabrina Servanty , Jean‐Michel Gaillard , Carole Toïgo , Serge Brandt , Eric Baubet
Published: June 2009

1.  Identifying which factors influence age and size at maturity is crucial for a better understanding of the evolution of life‐history strategies. In particular, populations intensively harvested, hunted or fished by humans often respond by displaying earlier age and decreased size at first reproduction.

2.
 Among ungulates wild boar (Sus scrofa scrofa L.) exhibit uncommon life‐history traits, such as high fertility and early reproduction, which might increase the demographic impact of varying age at first reproduction. We analysed variation in female reproductive output from a 22‐year long study of an intensively hunted population. We assessed how the breeding probability and the onset of oestrus responded to changes of female body mass at different ages under varying conditions of climate and food availability.

3.  Wild boar females had to reach a threshold body mass (27–33 kg) before breeding for the first time. This threshold mass was relatively low (33–41% of adult body mass) compared to that reported in most other ungulates (about 80%).

4.  Proportions of females breeding peaked when rainfall and temperature were low in spring and high in summer. Climatic conditions might act through the nutritional condition of females. The onset of oestrus varied a lot in relation to resources available at both current and previous years. Between none and up to 90% of females were in oestrus in November depending on the year.

5.  Past and current resources accounted for equivalent amount of observed variations in proportions of females breeding. Thus, wild boar rank at an intermediate position along the capital–income continuum rather than close to the capital end where similar‐sized ungulates rank.

6.  Juvenile females made a major contribution to the yearly reproductive output. Comparisons among wild boar populations facing contrasted hunting pressures indicate that a high demographic contribution of juveniles is a likely consequence of a high hunting pressure rather than a species‐specific life‐history pattern characterizing wild boar.