bluuebunny/crossref_metadata_2025 huggingface dataset:
Waveguide optical losses in InGaAs∕AlAsSb quantum cascade laser
Authors: Revin D. G. , Cockburn J. W. , Menzel S. , Yang Q. , Manz C. , Wagner J.
Published: February 2008

The authors present a technique for broadband study of the optical waveguides used for midinfrared quantum cascade lasers. This method allows insight into the waveguide properties and helps in improving the waveguide design. Using this method the waveguide losses in the whole range of waveguide transparency of about 1.8–9μm have been found for a λ∼4.4μm In0.53Ga0.47As∕AlAs0.56Sb0.44∕InP quantum cascade laser. The polarization dependence of waveguide losses in a quantum cascade laser is discussed.
Directional Brownian diffusion dynamics with variable magnitudes
Authors: Bhaduri Basanta , Neild Adrian , Ng Tuck Wah
Published: February 2008

The coupling effects of rotational and translational Brownian motion in anisotropic macromolecules result in differentiated diffusion constants parallel and perpendicular to the particle’s long axis in the short term. Investigations of these dynamics allow for a greater understanding of how directional alignment can be harnessed for applications. We investigate the dynamics using carbon nanofibers here and the results infer that significant reduction in the diffusion constants can result from probable hydrodynamic interactions. The diffusion constant perpendicular to the particle’s long axis is particularly reduced.
In situ investigation on dynamic suspending of microdroplet on lotus leaf and gradient of wettable micro- and nanostructure from water condensation
Authors: Zheng Yongmei , Han Dong , Zhai Jin , Jiang Lei
Published: February 2008

Dynamic suspending behavior of microdroplet on fresh lotus leaf is in situ investigated at micro- and nanolevels, by water condensation via environmental scanning electronic microscopy. The observation and analysis reveal that a gradient of wettable micro- and nanostructure is formed along the exterior surface of papilla including nanohairs during water condensation. This gradient introduces a tendency of directional movement and enables the microdroplet move out of the valley of papillae until the microdroplet is suspended on the tops of papillae. This finding is significant to understand the mechanism of self-cleaning.
Impact of annealing on morphology and ferromagnetism of ZnO nanorods
Authors: Yan Zijie , Ma Yanwei , Wang Dongliang , Wang Junhong , Gao Zhaoshun , Wang Lei , Yu Peng , Song Tao
Published: February 2008

Room temperature ferromagnetism has been observed in ZnO nanorods prepared by hydrothermal method. Saturation magnetization of ∼0.004emu∕g was measured in the nanorods with diameters of ∼10nm and lengths of below 100nm, and the magnetization reduced with the increase of the size. Annealing of the samples at 900°C in air completely transformed the nanorods into twinning structures and weakened the magnetizations. The mechanism of morphology transformation was discussed. Analysis indicates that the interstitial zinc at the surface may contribute to the ferromagnetism in ZnO nanorods.
Near-infrared organic light emitting diodes based on heavy metal phthalocyanines
Authors: Rosenow Thomas Conrad , Walzer Karsten , Leo Karl
Published: February 2008

We demonstrate near-infrared (NIR) organic light-emitting diodes containing the phthalocyanines of copper (CuPc), palladium (PdPc), and platinum (PtPc) as emitting material. The devices show NIR emission from the triplet excitonic states of those phthalocyanines at 1095, 1025, and 966nm, respectively. A yellow singlet emitter serves as host for the emitter materials, reducing triplet exciton quenching and improving energy transfer to the emitter. Using the emitter PtPc as guest and the yellow singlet emitter as host, an external quantum efficiency of 0.3% is achieved for infrared light emission at 966nm. Due to the use of electrically doped charge transport layers, operation at voltages significantly below 3V is possible. Light output reaches 80μW∕cm2 at a current density of 140mA∕cm2.
Effect of a metallic gate on the energy levels of a shallow donor
Authors: Slachmuylders A. F. , Partoens B. , Peeters F. M. , Magnus W.
Published: February 2008

We have investigated the effect of a metallic gate on the bound states of a shallow donor located near the gate. We calculate the energy spectrum as a function of the distance between the metallic gate and the donor and find an anticrossing behavior in the energy levels for certain distances. We show how a transverse electric field can tune the average position of the electron with respect to the metallic gate and the impurity.
Very high-efficiency organic light-emitting diodes based on cyclometallated rhenium (I) complex
Authors: Li Xiao , Zhang Dongyu , Li Wenlian , Chu Bei , Han Liangliang , Zhu Jianzhuo , Su Zisheng , Bi Defeng , Wang Dan , Yang Dongfang , Chen Yiren
Published: February 2008

A phosphorescent (Ph) cyclometallated rhenium (I) (ReI) complex was synthesized by reacting 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline with pentacarbonylbromorhenium in refluxing toluene solutions. The precipitates were easily sublimed to obtain a pure electrically neutral carbonyl diamine ReI complex, (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline)Re(CO)3Br. The Re complex was used as an orange emitting dopant in 4,4′-N,N′-dicarbazole-biphenyl host to fabricate Ph organic light-emitting diodes (PhOLEDs). The maximum electroluminescence (EL) efficiency and luminance of 21.8cd∕A and 8315cd∕cm2 were harvested, respectively, which were the highest EL results among the PhOLEDs based on ReI complexes. The improvements of the EL performances could be ascribed to the synergistic effects of together incorporation of two reciprocally repulsive phenyl and methyl groups on the backbone of 1,10-phenanthroline molecule of the ligand.
Electronic states in arsenic-decapped MnAs (11¯00) films grown on GaAs(001): A photoemission spectroscopy study
Authors: Moreno M. , Kumar A. , Tallarida M. , Horn K. , Ney A. , Ploog K. H.
Published: February 2008

We examine the arsenic bonding in the near-surface region of initially arsenic-capped MnAs(11¯00) films grown on GaAs(001), as it evolves upon arsenic decapping. Line-shape analyses of high-resolution As 3d photoelectron emission spectra recorded at room temperature (RT) allow us to identify electronically distinct As-bonding states associated to bulk MnAs phases, bulk arsenic, and interfacial environments. Stable MnAs phases appear to be affected by the presence of a thin arsenic coating, an effect that could be advantageously used to enhance the ferromagnetic properties of MnAs films around RT.
Differential conductance fluctuations in silicon nanowire transistors caused by quasiballistic transport and scattering induced intersubband transitions
Authors: Jin Seonghoon , Fischetti Massimo V. , Tang Ting-wei
Published: February 2008

Calculations based on the multisubband Boltzmann transport equation with relevant microscopic scattering mechanisms predict abrupt differential conductance fluctuations (kinks) in the drain current versus drain voltage curves of silicon nanowire transistors at room temperature. The kink originates from the change of series resistance at the drain extension related to the interplay between quasiballistic transport and intersubband transitions of electrons caused by elastic interactions with acoustic phonons, surface roughness, and ionized impurities. The kink occurs when the energy of the second subband in the drain extension is aligned with the peak of the net electron flux distribution in the first subband. This bias condition yields a large series resistance in the drain extension because those quasiballistic electrons in the first subband which reach the drain can scatter isotropically into the second subband.
A new apparatus for measurement of capacitance change in soft materials
Authors: Kobayashi Takashi , Nakajima Haruhiko
Published: February 2008

We have developed an apparatus with LC resonance circuit to measure a fast capacitance change accompanied by freezing of a supercooled water droplet that was placed in a capacitor space formed by a set of a needle and a copper plate. A trace of the capacitance change obtained exhibits a first rapid increase, a gradual growth, and a final steady state. The experimental capacitance change is in good agreement with that of the capacitance calculated with the finite element method.
Development of the pharyngeal dentition of two herbivorous halfbeaks (Teleostei : Hemiramphidae) and implications for the hemiramphid ontogenetic trophic shift
Authors: Tibbetts Ian R. , Day Ryan D. , Carseldine Lee
Published: February 2008

Development of the pharyngeal dentition of two herbivorous halfbeaks, Hyporhamphus regularis ardelio (Whitley, 1931) and Arrhamphus sclerolepis krefftii (Steindachner, 1867), was examined quantitatively to assess features that might confer their ability to shift their diet from animal to plant material. Toothed area, tooth number, maximum tooth diameter and tooth wear area in both pharyngeal tooth pads of both taxa increased with ontogeny, whereas tooth density decreased. Comparing individuals of the two taxa at similar standard lengths indicated that A. sclerolepis krefftii showed hypertrophy of the majority of pharyngeal characters in relation to H. regularis ardelio of a similar standard length. That A. sclerolepis krefftii is more developmentally advanced than H. regularis ardelio in almost all dentigerous characters studied indicates that pharyngeal development may allow the former to commence herbivory at a smaller standard length than the latter species. The evolutionary and ecological implications of these findings are discussed in the context of a group of fishes that is overexploited worldwide.
A field and experimental study on the tolerances of fish to Eucalyptus camaldulensis leachate and low dissolved oxygen concentrations
Authors: McMaster Damien , Bond Nick
Published: February 2008

In intermittent streams, deteriorating water quality during drying influences fish survival but the specific effects of individual variables and their interactions are poorly known. During summer 2002 and 2004, fish were surveyed in isolated pools of two lowland intermittent streams in south-east Australia. Despite a low dissolved oxygen (DO, range = 0.4–6.8 mg L–1) and high dissolved organic carbon (DOC, 16–50 mg L–1) concentrations, assemblage composition and abundance of native fish appeared unaffected. In subsequent laboratory experiments, concentrations of DO and DOC were independently manipulated to identify better the tolerance of these species to extremes in environmental conditions. At low DOC concentrations (20 mg L–1), no significant effects were observed. At high DOC concentrations (50, 70 and 80 mg L–1), an interaction was observed between DOC and DO, with significant reductions in resistance (decreased time to loss of buoyancy). At extreme DOC concentrations (99 mg L–1), the effect of DO appeared to have been overridden by a strong effect from DOC (rapid loss of equilibrium). The thresholds observed suggest these species have a high resistance to ‘blackwater events’ caused by leaching of DOC from terrestrial leaf litter. Our findings are consistent with the observed tolerances of fish occupying habitats, both in Australia and elsewhere in the world, where extreme physicochemical conditions are a regular and predictable occurrence.
The enzyme mechanism of nitrite reductase studied at single-molecule level
Authors: Kuznetsova Sofya , Zauner Gerhild , Aartsma Thijs J. , Engelkamp Hans , Hatzakis Nikos , Rowan Alan E. , Nolte Roeland J. M. , Christianen Peter C. M. , Canters Gerard W.
Published: February 2008

A generic method is described for the fluorescence “readout” of the activity of single redox enzyme molecules based on Förster resonance energy transfer from a fluorescent label to the enzyme cofactor. The method is applied to the study of copper-containing nitrite reductase from
Alcaligenes faecalis
S-6 immobilized on a glass surface. The parameters extracted from the single-molecule fluorescence time traces can be connected to and agree with the macroscopic ensemble averaged kinetic constants. The rates of the electron transfer from the type 1 to the type 2 center and back during turnover exhibit a distribution related to disorder in the catalytic site. The described approach opens the door to single-molecule mechanistic studies of a wide range of redox enzymes and the precise investigation of their internal workings.
Microarray analyses reveal that plant mutagenesis may induce more transcriptomic changes than transgene insertion
Authors: Batista Rita , Saibo Nelson , Lourenço Tiago , Oliveira Maria Margarida
Published: February 2008

Controversy regarding genetically modified (GM) plants and their potential impact on human health contrasts with the tacit acceptance of other plants that were also modified, but not considered as GM products (e.g., varieties raised through conventional breeding such as mutagenesis). What is beyond the phenotype of these improved plants? Should mutagenized plants be treated differently from transgenics? We have evaluated the extent of transcriptome modification occurring during rice improvement through transgenesis versus mutation breeding. We used oligonucleotide microarrays to analyze gene expression in four different pools of four types of rice plants and respective controls: (
i
) a γ-irradiated stable mutant, (
ii
) the M1 generation of a 100-Gy γ-irradiated plant, (
iii
) a stable transgenic plant obtained for production of an anticancer antibody, and (
iv
) the T1 generation of a transgenic plant produced aiming for abiotic stress improvement, and all of the unmodified original genotypes as controls. We found that the improvement of a plant variety through the acquisition of a new desired trait, using either mutagenesis or transgenesis, may cause stress and thus lead to an altered expression of untargeted genes. In all of the cases studied, the observed alteration was more extensive in mutagenized than in transgenic plants. We propose that the safety assessment of improved plant varieties should be carried out on a case-by-case basis and not simply restricted to foods obtained through genetic engineering.
Impact of an extreme climatic event on community assembly
Authors: Thibault Katherine M. , Brown James H.
Published: February 2008

Extreme climatic events are predicted to increase in frequency and magnitude, but their ecological impacts are poorly understood. Such events are large, infrequent, stochastic perturbations that can change the outcome of entrained ecological processes. Here we show how an extreme flood event affected a desert rodent community that has been monitored for 30 years. The flood (i) caused catastrophic, species-specific mortality; (ii) eliminated the incumbency advantage of previously dominant species; (iii) reset long-term population and community trends; (iv) interacted with competitive and metapopulation dynamics; and (v) resulted in rapid, wholesale reorganization of the community. This and a previous extreme rainfall event were punctuational perturbations—they caused large, rapid population- and community-level changes that were superimposed on a background of more gradual trends driven by climate and vegetation change. Captured by chance through long-term monitoring, the impacts of such large, infrequent events provide unique insights into the processes that structure ecological communities.
Tocopherols Modulate Extraplastidic Polyunsaturated Fatty Acid Metabolism inArabidopsisat Low Temperature
Authors: Maeda Hiroshi , Sage Tammy L. , Isaac Giorgis , Welti Ruth , DellaPenna Dean
Published: February 2008

Tocopherols (vitamin E) are synthesized in plastids and have long been assumed to have essential functions restricted to these organelles. We previously reported that the vitamin e-deficient2 (vte2) mutant of Arabidopsis thaliana is defective in transfer cell wall development and photoassimilate transport at low temperature (LT). Here, we demonstrate that LT-treated vte2 has a distinct composition of polyunsaturated fatty acids (PUFAs): lower levels of linolenic acid (18:3) and higher levels of linoleic acid (18:2) compared with the wild type. Enhanced 18:3 oxidation was not involved, as indicated by the limited differences in oxidized lipid species between LT-treated vte2 and the wild type and by a lack of impact on the LT-induced vte2 phenotype in a vte2 fad3 fad7 fad8 quadruple mutant deficient in 18:3. PUFA changes in LT-treated vte2 occur primarily in phospholipids due to reduced conversion of dienoic to trienoic fatty acids in the endoplasmic reticulum (ER) pathway. Introduction of the ER fatty acid desaturase mutation, fad2, and to a lesser extent the plastidic fad6 mutation into the vte2 background suppressed the LT-induced vte2 phenotypes, including abnormal transfer cell wall development. These results provide biochemical and genetic evidence that plastid-synthesized tocopherols modulate ER PUFA metabolism early in the LT adaptation response of Arabidopsis.
Orthotopic implantation mouse model and cDNA microarray analysis indicates several genes potentially involved in lymph node metastasis of colorectal cancer
Authors: Sasaki Hiroyuki , Miura Koh , Horii Akira , Kaneko Naoyuki , Fujibuchi Wataru , Kiseleva Larisa , Gu Zhaodi , Murata Yukio , Karasawa Hideaki , Mizoi Takayuki , Kobayashi Terutada , Kinouchi Makoto , Ohnuma Shinobu , Yazaki Nobuki , Unno Michiaki , Sasaki Iwao
Published: February 2008

In colorectal cancer (CRC) patients, metastasis to the regional lymph node (LN) is an important first step in the dissemination of cancers. To identify the genes possibly involved in LN metastasis of CRC, we analyzed LN metastases in an orthotopic implantation mouse model with 22 CRC cell lines using Matrigel, an extracellular matrix protein derived from mice sarcoma, and combined the data with gene expression profiles of cDNA microarray of those cell lines. With this implantation analysis, the incidence of LN metastasis was 60% in 228 orthotopically implanted mice and varied from 100% to 0% among the cell lines. KM12c and Clone A showed LN metastasis in all orthotopically implanted mice, but DLD‐1, HCT‐8, and SW948 did not show LN metastases at all. In contrast, the incidence of liver and lung metastasis in 22 CRC cell lines was 13% and 1%, respectively. Combining those data with cDNA microarray in vitro, we isolated 636 genes that were differentially expressed depending on the incidence of LN metastasis. Among those genes, the expression level of ring finger protein 125 (RNF125), previously known as an E3 ubiquitin ligase in T cell activation, was significantly different between primary tumors in Stage III CRC patients with LN metastasis and Stage II patients without LN metastasis. In conclusion, the orthotopic implantation mice model with Matrigel was useful, and we isolated candidate genes such as RNF125 that possibly play an important role in LN metastasis of CRC cells. (Cancer Sci 2008; 99: 711–719)
Susceptibility of Snark‐deficient mice to azoxymethane‐induced colorectal tumorigenesis and the formation of aberrant crypt foci
Authors: Tsuchihara Katsuya , Ogura Tsutomu , Fujioka Rumi , Fujii Satoshi , Kuga Wataru , Saito Marie , Ochiya Takahiro , Ochiai Atsushi , Esumi Hiroyasu
Published: February 2008

SNF‐1/5′‐AMP‐activated kinase (AMPK)‐related kinase (SNARK) is a member of the AMPK‐related kinases. Snark+/– mice exhibited mature‐onset obesity and related metabolic disorders. Obesity is regarded as a risk factor for colorectal cancer. To investigate whether Snark deficiency is involved in tumorigenesis in the large intestine, obese Snark+/– mice were treated with a chemical carcinogen, azoxymethane (AOM). The incidences of both adenomas and aberrant crypt foci (ACF) were significantly higher in Snark+/– mice than in their wild‐type counterparts 28 weeks after the completion of AOM treatment (10 mg/kg/week for 8 weeks). Furthermore, ACF formation was enhanced in Snark+/– mice treated with AOM for 2 weeks, suggesting that Snark deficiency contributed to the early phase of tumorigenesis. The total number of ACF was correlated with bodyweight in Snark+/– and Snark+/+ mice, suggesting that obesity was a risk factor for colorectal tumorigenesis in this model. However, the correlation coefficient was higher in Snark+/– mice. Moreover, AOM‐induced ACF formation was also enhanced in preobese Snark+/– mice. Together, these findings suggest that AOM‐induced tumorigenesis in Snark+/– mice was enhanced via obesity‐dependent and ‐independent mechanisms. (Cancer Sci 2008; 99: 677–682)
Sedimentation record in the Konkan–Kerala Basin: implications for the evolution of the Western Ghats and the Western Indian passive margin
Authors: Campanile D. , Nambiar C. G. , Bishop P. , Widdowson M. , Brown R.
Published: February 2008

The Konkan and Kerala Basins constitute a major depocentre for sediment from the onshore hinterland of Western India and as such provide a valuable record of the timing and magnitude of Cenozoic denudation along the continental margin. This paper presents an analysis of sedimentation in the Konkan–Kerala Basin, coupled with a mass balance study, and numerical modelling of flexural responses to onshore denudational unloading and offshore sediment loading in order to test competing conceptual models for the development of high‐elevation passive margins. The Konkan–Kerala Basin contains an estimated 109 000 km3of Cenozoic clastic sediment, a volume difficult to reconcile with the denudation of a downwarped rift flank onshore, and more consistent with denudation of an elevated rift flank. We infer from modelling of the isostatic response of the lithosphere to sediment loading offshore and denudation onshore infer that flexure is an important component in the development of the Western Indian Margin. There is evidence for two major pulses in sedimentation: an early phase in the Palaeocene, and a second beginning in the Pliocene. The Palaeocene increase in sedimentation can be interpreted in terms of a denudational response to the rifting between India and the Seychelles, whereas the mechanism responsible for the Pliocene pulse is more enigmatic.
Fold evolution and drainage development in the Zagros mountains of Fars province, SE Iran
Authors: Ramsey Lucy A. , Walker Richard T. , Jackson James
Published: February 2008

A central question in structural geology is whether, and by what mechanism, active faults (and the folds often associated with them) grow in length as they accumulate displacement. An obstacle in our understanding of these processes is the lack of examples in which the lateral growth of active structures can be demonstrated definitively, as geomorphic indicators of lateral propagation are often difficult, or even impossible to distinguish from the effects of varying lithology or non‐uniform displacement and slip histories. In this paper we examine, using the Zagros mountains of southern Iran as our example, the extent to which qualitative analysis of satellite imagery and digital topography can yield insight into the growth, lateral propagation, and interaction of individual fold segments in regions of active continental shortening. The Zagros fold‐and‐thrust belt contains spectacular whaleback anticlines that are well exposed in resistant Tertiary and Mesozoic limestone, are often >100 km in length, and which contain a large proportion of the global hydrocarbon reserves. In one example, Kuh‐e Handun, where an anticline is mantled by soft Miocene sediments, direct evidence of lateral fold propagation is recorded in remnants of consequent drainage patterns on the fold flanks that do not correspond to the present‐day topography. We suggest that in most other cases, the soft Miocene and Pliocene sediments that originally mantled the folds, and which would have recorded early stages in the growth histories, have been completely stripped away, thus removing any direct geomorphic evidence of lateral propagation. However, many of the long fold chains of the Zagros do appear to be formed from numerous segments that have coalesced. If our interpretations are correct, the merger of individual fold segments that have grown in length is a major control on the development of through‐going drainage and sedimentation patterns in the Zagros, and may be an important process in other regions of crustal shortening as well. Abundant earthquakes in the Zagros show that large seismogenic thrust faults must be present at depth, but these faults rarely reach the Earth's surface, and their relationship to the surface folding is not well constrained. The individual fold segments that we identify are typically 20–40 km in length, which correlates well with the maximum length of the seismogenic basement faults suggested from the largest observed thrusting earthquakes. This correlation between the lengths of individual fold segments and the lengths of seismogenic faults at depth suggest that it is possible, at least in some cases, that there may be a direct relationship between folding and faulting in the Zagros, with individual fold segments underlain by discrete thrusts.
Basin modelling of the Limón Back‐arc Basin (Costa Rica): burial history and temperature evolution of an island arc‐related basin‐system
Authors: Brandes C. , Astorga A. , Littke R. , Winsemann J.
Published: February 2008

The Limón back‐arc basin belongs to the southern Central American arc‐trench system and is situated at the east coast of Costa Rica. The basin‐fill consists of Late Cretaceous to Pleistocene sedimentary rocks. A northern and a southern sub‐basin can be defined, separated by the E–W‐trending Trans Isthmic Fault System. The North Limón Basin is nearly undeformed, whereas the South Limón Basin is characterized by a fold‐and‐thrust belt. Both sub‐basins have a very similar sedimentary fill and can act as a natural laboratory for reconstructing controlling factors of arc‐related sedimentary basins as well as the influence of deformation on a basin system. Modelling focused on burial history and temperature evolution. Two‐dimensional simulations were carried out with the software PetroMod®. The geohistory curve of the North Limón Basin is overall linear, indicating continuous subsidence. The South Limón Basin is also characterized by continuous subsidence, but rates strongly increased at the beginning of the Neogene. Despite a rapid Plio‐Pleistocene deformation of the fold‐and‐thrust belt, the present‐day temperature field is not disturbed in that area. The modelling results indicate a mean heat flow of 60 mW m−2 for the North Limón Basin and 41 mW m−2 for the South Limón Basin. These values are low compared with other back‐arc basins. The lower values are attributed to the following effects: (1) underlying basaltic crust, (2) the lack of an initial rift phase, (3) the low extension rates, (4) absence of volcanic activity and (5) insulation effects of a thick sediment pile. The reasons for the locally lower heat flow in the southern sub‐basin can be found in the low‐angle subduction of the Cocos Ridge. Owing to the low subduction angle, the cool fore‐arc mantle‐wedge below the island‐arc is pushed backwards increasing the cooled area.
An optimized ibuprofen dosing scheme for preterm neonates with patent ductus arteriosus, based on a population pharmacokinetic and pharmacodynamic study
Authors: Hirt Déborah , Van Overmeire Bart , Treluyer Jean‐Marc , Langhendries Jean‐Paul , Marguglio Arnaud , Eisinger Mark J. , Schepens Paul , Urien Saïk
Published: February 2008

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

• Ibuprofen is a nonsteroidal anti‐inflammatory agent that induces closure of the patent ductus arteriosus in neonates.

• Few studies of ibuprofen pharmacokinetics have been performed and were limited to small groups of preterm infants, showing a large intersubject variability and an increase in clearance with either postnatal or gestational age.

WHAT THIS STUDY ADDS

• A population pharmacokinetic study was performed on 66 neonates to characterize the concentration‐time courses of ibuprofen.

• Ibuprofen clearance significantly increased from postnatal age day 1 to day 8, but not with gestational age.

• A relationship was shown between ibuprofen area under the curve (AUC) and patent ductus arteriosus closure rate, and an effective threshold AUC was evidenced.

• Dosing schemes were proposed as a function of postnatal age, to achieve this AUC and to improve the efficacy of treatment for patent ductus arteriosus in neonates.

AIMS

To describe ibuprofen pharmacokinetics in preterm neonates with patent ductus arteriosus (PDA) and to establish relationships between doses, plasma concentrations and ibuprofen efficacy and safety.

METHODS

Sixty‐six neonates were treated with median daily doses of 10, 5 and 5 mg kg−1 of ibuprofen‐lysine by intravenous infusion on 3 consecutive days. A population pharmacokinetic model was developed with NONMEM. Bayesian individual pharmacokinetic estimates were used to calculate areas under the curve (AUC) and to simulate doses. A logistic regression was performed on PDA closure.

RESULTS

Ibuprofen pharmacokinetics were described by a one‐compartment model with linear elimination. Mean population pharmacokinetic estimates with corresponding intersubject variabilities (%) were: elimination clearance CL = 9.49 ml h−1 (62%) and volume of distribution V = 375 ml (72%). Ibuprofen CL significantly increased with postnatal age (PNA): CL = 9.49*(PNA/96.3)1.49. AUC after the first dose (AUC1D), the sum of AUC after the three doses (AUC3D) and gestational age were significantly higher in 57 neonates with closing PDA than in nine neonates without PDA closure (P = 0.02). PDA closure was observed in 50% of the neonates when AUC1D < 600 mg l−1 h (or AUC3D < 900 mg l−1 h) and in 91% when AUC1D > 600 mg l−1 h (or AUC3D > 900 mg l−1 h) (P = 0.006). No correlation between AUC and side‐effects could be demonstrated.

CONCLUSIONS

To achieve these optimal AUCs, irrespective of gestational age, three administrations at 24 h intervals are recommended of 10, 5, 5 mg kg−1 for neonates younger than 70 h, 14, 7, 7 mg kg−1 for neonates between 70 and 108 h and 18, 9, 9 mg kg−1 for neonates between 108 and 180 h.
Fluctuations in circumpolar seabird populations linked to climate oscillations
Authors: IRONS DAVID B. , ANKER‐NILSSEN TYCHO , GASTON ANTHONY J. , BYRD G. VERNON , FALK KNUD , GILCHRIST GRANT , HARIO MARTTI , HJERNQUIST MÅNS , KRASNOV YURI V. , MOSBECH ANDERS , OLSEN BERGUR , PETERSEN AEVAR , REID JAMES B. , ROBERTSON GREGORY J. , STRØM HALLVARD , WOHL KENTON D.
Published: February 2008

We found that synchronous fluctuations of two congeneric seabird species across the entire Arctic and sub‐Arctic regions were associated with changes in sea surface temperatures (SST) that were linked to two climate shifts, in 1977 and again in 1989. As the SST changes linked to climate shifts were congruent at the scale of ocean basins, fluctuations of these species occurred similarly at continental or basin scale. Changes in colony sizes were examined for a decade following climate shifts. The magnitude of the SST shift was more important than its direction in determining the subsequent rate of population change. Seabirds declined when the SST shift was large and increased when the shift was small, although the effect differed between the Arctic‐breeding species and the more temperate‐breeding congener. The Arctic species, Thick‐billed Murre (Uria lomvia) increased most rapidly when SST warmed slightly, while the temperate species, Common Murre (Uria aalge) showed most rapid increase with moderate cooling. Both showed negative trends with large temperature shifts in either direction. This pattern was replicated during both climate oscillations. Negative population trends in seabirds presumably indicate the alteration of underlying food webs. Hence, similar widespread fluctuations in response to climate shifts are likely for other ecosystem components (marine mammals, fish, and invertebrates).
Effects of vegetation control on ecosystem water use efficiency within and among four grassland ecosystems in China
Authors: HU ZHONGMIN , YU GUIRUI , FU YULING , SUN XIAOMIN , LI YINGNIAN , SHI PEILI , WANG YANFEN , ZHENG ZEMEI
Published: February 2008

Through 2–3‐year (2003–2005) continuous eddy covariance measurements of carbon dioxide and water vapor fluxes, we examined the seasonal, inter‐annual, and inter‐ecosystem variations in the ecosystem‐level water use efficiency (WUE, defined as the ratio of gross primary production, GPP, to evapotranspiration, ET) at four Chinese grassland ecosystems in the Qinghai‐Tibet Plateau and North China. Representing the most prevalent grassland types in China, the four ecosystems are an alpine swamp meadow ecosystem, an alpine shrub‐meadow ecosystem, an alpine meadow‐steppe ecosystem, and a temperate steppe ecosystem, which illustrate a water availability gradient and thus provide us an opportunity to quantify environmental and biological controls on ecosystem WUE at different spatiotemporal scales. Seasonally, WUE tracked closely with GPP at the four ecosystems, being low at the beginning and the end of the growing seasons and high during the active periods of plant growth. Such consistent correspondence between WUE and GPP suggested that photosynthetic processes were the dominant regulator of the seasonal variations in WUE. Further investigation indicated that the regulations were mainly due to the effect of leaf area index (LAI) on carbon assimilation and on the ratio of transpiration to ET (T/ET). Besides, except for the swamp meadow, LAI also controlled the year‐to‐year and site‐to‐site variations in WUE in the same way, resulting in the years or sites with high productivity being accompanied by high WUE. The general good correlation between LAI and ecosystem WUE indicates that it may be possible to predict grassland ecosystem WUE simply with LAI. Our results also imply that climate change‐induced shifts in vegetation structure, and consequently LAI may have a significant impact on the relationship between ecosystem carbon and water cycles in grasslands.
Dependence of surface monoclonal antibody binding on dynamic changes in FcγRIIb expression
Authors: Walker Jennifer A. , Smith Kenneth G. C.
Published: February 2008

Receptors for the Fc region of immunoglobulin G (FcγRs) are expressed on a broad range of haematopoietic cell types and are responsible for regulating antibody production and linking the humoral and effector responses. In response to a number of stimuli, such as cytokine signals or inflammation, FcγR expression at the cell surface is dynamically regulated. On B cells, we observed what appeared to be a correlation between CD22 expression and FcγRIIb expression when the latter was varied in a number of models. Further investigation revealed that this was specific to a particular anti‐CD22 monoclonal antibody, which appeared to require stabilization by interaction with FcγRIIb for optimal binding to CD22. Since alterations in the regulation of FcγR expression are important in controlling immune responses and have been associated with a number of immune‐mediated disease states, we suggest that it might be prudent to confirm the expression of cell surface markers by two independent methods. Furthermore, because the efficacy of therapeutic antibodies may depend upon their interaction with FcγRs, our results are relevant to their design and assessment.
Distinct in vivo roles of CD80 and CD86 in the effector T‐cell responses inducing antigen‐induced arthritis
Authors: Odobasic Dragana , Leech Michelle T. , Xue Jin R. , Holdsworth Stephen R.
Published: February 2008

CD80 and CD86 play a critical role in the initiation of T‐cell responses. However, their role in the in vivo effector CD4+ T‐cell responses has been less extensively investigated. The current studies have examined the functional relevance of CD80 and CD86 in the effector CD4+ T‐cell responses inducing antigen‐induced arthritis. Arthritis was induced in C57BL/6 mice by sensitization to methylated bovine serum albumin (mBSA) on day 0, booster immunization (day 7) and intra‐articular injection of mBSA (day 21). Control or anti‐CD80 and/or anti‐CD86 monoclonal antibodies were administered from day 21 to day 28. Arthritis severity and immune responses were assessed on day 28. The development of arthritis was significantly suppressed by inhibition of CD80 or CD86. Blockade of both CD80 and CD86 caused a trend towards reduced disease severity compared to control antibody‐treated mice. Neutralization of CD80 attenuated accumulation of CD4+ T cells in joints and enhanced splenocyte production and circulating levels of interleukin‐4. Inhibition of CD86 or both CD80 and CD86 reduced T‐cell accumulation in joints without affecting T helper type 1/type 2 (Th1/Th2) differentiation or antibody levels. Blockade of CD86, and not CD80, significantly suppressed splenocyte interleukin‐17 (IL‐17) production. These results provide further in vivo evidence that CD80 and CD86 play important pathogenic roles in effector T‐cell responses. CD80 exacerbates arthritis by downregulating systemic levels of IL‐4 and increasing T‐cell accumulation in joints without affecting IL‐17 production. CD86 enhances disease severity by upregulating IL‐17 production and increasing the accumulation of effector T cells in joints without affecting Th1/Th2 development.
Spatial pattern formation facilitates eradication of infectious diseases
Authors: Eisinger Dirk , Thulke Hans‐Hermann
Published: February 2008

Control of animal‐born diseases is a major challenge faced by applied ecologists and public health managers. To improve cost‐effectiveness, the effort required to control such pathogens needs to be predicted as accurately as possible. In this context, we reviewed the anti‐rabies vaccination schemes applied around the world during the past 25 years.

We contrasted predictions from classic approaches based on theoretical population ecology (which governs rabies control to date) with a newly developed individual‐based model. Our spatially explicit approach allowed for the reproduction of pattern formation emerging from a pathogen's spread through its host population.

We suggest that a much lower management effort could eliminate the disease than that currently in operation. This is supported by empirical evidence from historic field data. Adapting control measures to the new prediction would save one‐third of resources in future control programmes.

The reason for the lower prediction is the spatial structure formed by spreading infections in spatially arranged host populations. It is not the result of technical differences between models.

Synthesis and applications. For diseases predominantly transmitted by neighbourhood interaction, our findings suggest that the emergence of spatial structures facilitates eradication. This may have substantial implications for the cost‐effectiveness of existing disease management schemes, and suggests that when planning management strategies consideration must be given to methods that reflect the spatial nature of the pathogen–host system.
The impact of ecosystem connectivity on coral reef resilience
Authors: Mumby Peter J , Hastings Alan
Published: February 2008

Ontogenetic dispersal of animals has been observed among many ecosystems, but its full ecological significance is poorly understood. By modelling the consequences of ontogenetic reef fish dispersal between Caribbean mangroves and adjacent coral reefs, we quantify the broader implications of ecosystem connectivity for ecosystem function and resilience to climate‐driven disturbance.

Mangrove‐driven enrichment of parrotfish grazing on two coral reef habitats was calculated using empirical data. The consequences of increased grazing were then investigated using a spatial simulation of coral reef dynamics in shallow (depth 3–6 m) and mid‐shelf forereefs (depth 7–15 m).

The largest increase in grazing occurred in shallow reefs, but was found to have negligible consequences for coral population dynamics.

In contrast, relatively weak increases in grazing on deeper reefs had profound consequences: reefs near mangroves were able to experience coral recovery under the most intense hurricane regimes of the Caribbean, whereas those lacking ecosystem connectivity had little capacity for recovery.

This surprising result occurs because reefs exhibit multiple stable equilibria and mangrove enrichment of grazing in mid‐shelf reefs coincides with a zone of system instability. A small increase in grazing shifted the reef beyond a bifurcation point, thereby enhancing resilience massively. A relatively large increase in grazing in shallow reefs had minimal ecosystem consequence because the grazing levels concerned were more than double the levels needed to exceed the corresponding bifurcation point for this habitat.

Synthesis and applications. Caribbean mangroves are being deforested at a faster rate than rainforests, yet their protective role against hurricane damage extends not only shoreward to coastal environments but also seaward to increasing the resilience of offshore coral reefs. Specifically, ontogenetic mechanisms of ecosystem connectivity involving parrotfish may increase the probability that coral populations will recover from climate‐induced changes in hurricane disturbance. Efforts to arrest mangrove deforestation and restore mangrove habitats are likely to increase the likelihood of recovery of corals on mid‐depth (7–15 m) reefs after disturbance. In general, the ecosystem‐level consequences of ontogenetic migration do not correspond necessarily to the magnitude of locally observed effects (i.e. the pattern of grazer enrichment exhibited the opposite pattern to that of its consequences for system resilience). Therefore, caution must be exercised when interpreting the functional significance of changes in species abundance for ecosystem process (e.g. grazing pressure and its implications for coral growth and survival). Impacts of shifting abundance or process are perhaps best appreciated using mechanistic ecosystem models.
The pharmacokinetics of meloxicam in vultures
Authors: NAIDOO V. , WOLTER K. , CROMARTY A. D. , BARTELS P. , BEKKER L. , McGAW L. , TAGGART M. A. , CUTHBERT R. , SWAN G. E.
Published: February 2008

Vulture populations across the Asian subcontinent have declined dramatically in the last 15 years and are now on the verge of extinction. Although the cause of the population decline was initially unknown, the decrease has recently been conclusively linked to the use of the nonsteroidal anti‐inflammatory drug diclofenac in cattle that inadvertently ended up in the vulture food chain. With the vulture numbers continuing to decline by up to 48% a year, the Indian, Nepali and Pakistan governments have recently banned the manufacture and importation of veterinary diclofenac. They have also suggested meloxicam as an alternate anti‐inflammatory for use in cattle. This recommendation was based on extensive acute safety studies in the African White‐backed vulture (Gyps africanus), which evaluated worst case scenarios of maximum intake based on a once in three day feeding pattern. However, the possible cumulative pharmacokinetic and pharmacodynamic effects in vultures receiving multiple daily doses of meloxicam over time were not assessed. At present very little pharmacokinetic or pharmacodynamic information is available to add further support for the safety of meloxicam in this animal species. This article discusses the oral and intramuscular pharmacokinetics of meloxicam in Cape Griffon vultures (Gyps coprotheres). Therapeutic drug monitoring was also undertaken in White‐backed, Egyptian (Neophron pernopterus) and one Lappet Faced vulture (Torgos tracheliotos). In all these species, meloxicam was characterized by a short half‐life of elimination. The rapid metabolism of meloxicam in combination with a short duration of effect in the studied species Gyps vultures shown in this study makes it unlikely that the drug could accumulate. This confirms the safety of repeated exposure to meloxicam in vultures of this genus.
Ancient vs. recent processes as factors shaping the genetic variation of the European wild boar: are the effects of the last glaciation still detectable?
Authors: SCANDURA M. , IACOLINA L. , CRESTANELLO B. , PECCHIOLI E. , DI BENEDETTO M. F. , RUSSO V. , DAVOLI R. , APOLLONIO M. , BERTORELLE G.
Published: February 2008

The European wild boar is an important game species, subjected to local extinctions and translocations in the past, and currently enormously and worryingly expanding in some areas where management is urgently required. Understanding the relative roles of ancient and recent events in shaping the genetic structure of this species is therefore not only an interesting scientific issue, but it represents also the basis for addressing future management strategies. In addition, several pig breeds descend from the European wild boar, but the geographical location of the domestication area(s) and the possible introgression of pig genomes into wild populations are still open questions. Here, we analysed the genetic variation in different wild boar populations in Europe. Ten polymorphic microsatellites were typed in 252 wild boars and the mtDNA control region was sequenced in a subset of 145 individuals. Some samples from different pig breeds were also analysed. Our results, which were obtained considering also 612 published mtDNA sequences, suggest that (i) most populations are similarly differentiated, but the major discontinuity is found along the Alps; (ii) except for the Italian populations, European wild boars show the signature of a postglacial demographic expansion; (iii) Italian populations seem to preserve a high proportion of preglaciation diversity; (iv) the demographic decline which occurred in some areas in the last few centuries did not produce a noticeable reduction of genetic variation; (v) signs of human‐mediated gene flow among populations are weak, although in some regions the effects of translocations are detectable and a low degree of pig introgression can be identified; (vi) the hypothesis of an independent domestication centre in Italy is not supported by our data, which in turn confirm that Central European wild boar might have represented an important source for domestic breeds. We can therefore conclude that recent human activities had a limited effect on the wild boar genetic structure. It follows that areas with high variation and differentiation represent natural reservoirs of genetic diversity to be protected avoiding translocations. In this context controlling some populations by hunting is not expected to affect significantly genetic variation in this species.