bluuebunny/crossref_metadata_2025 huggingface dataset:
Obstetric outcomes of low-risk labors at ‘Japanese tatami’ mat delivery room: a preliminary study
Authors: Suzuki Shunji
Published: July 2009

Objective: We examined the obstetric outcomes of low-risk labors at the ‘Japanese tatami’ mat compared with Western-style delivery room.

Methods: A retrospective cohort study was performed on 201 deliveries at the ‘Japanese tatami’ delivery room and 360 deliveries at the standard Western-style delivery room.

Results: There were no measurable differences in the duration of labor, the incidence of perineal laceration, total maternal blood loss and the incidence of low Apgar score and umbilical artery pH between the two groups.

Conclusions: We found no evidence that the Japanese room is unsafe for low-risk infants and mothers in comparison with the standard Western-style delivery room.
Nuchal translucency and lymphatic system maldevelopment
Authors: Bellini Carlo , Rutigliani Mariangela , Boccardo Francesco M. , Bonioli Eugenio , Campisi Corradino , Grillo Federica , Bellini Tommaso , Valenzano Mario , Fulcheri Ezio
Published: July 2009

We describe the histological examination of 18 aborted fetuses that had increased nuchal translucency (NT) between 11+0 and 13+6 weeks' gestation. The aim of this study was to assess the corresponding NT anatomic features by immunohistochemical (IHC) investigation. A morphological study was performed using lymphatic and blood endothelial specific markers, as well as smooth muscle actin (SMA). We found that all 18 cases were D2-40 positive, CD31 positive, and CD34 negative, suggesting the presence of nuchal lymph vessel ectasia. We found that 12/18 cases were SMA staining positive and 6/18 cases were SMA negative, suggesting that 6/18 cases had nuchal cystic lymphangiectasia, whereas 12/18 had cystic hygromas. The present data seem to confirm the reasonable hypothesis that lymphangiogenesis plays a relevant role in nuchal edema, increased NT, and that increased NT is the result of a lymphatic malformation or a delayed development of the lymphatic system.
High incidence of low O6-methylguanine DNA methyltransferase expression in invasive macroadenomas of Cushing's disease
Authors: Takeshita Akira , Inoshita Naoko , Taguchi Manabu , Okuda Chikao , Fukuhara Noriaki , Oyama Kenichi , Ohashi Kenichi , Sano Toshiaki , Takeuchi Yasuhiro , Yamada Shozo
Published: July 2009

Context

Crooke's cell adenoma (CCA), characterized by massive Crooke's hyaline change in corticotroph adenoma, causes a rare subtype of Cushing's disease. In contrast to ordinary corticotroph adenomas, CCAs are generally aggressive and present as invasive macroadenomas, which are refractory to both surgery and radiotherapy and have a high-recurrence rate. Moreover, some patients with CCA present with distant or craniospinal metastases. Currently, there are no effective standard therapies for CCA.

Objective

We report a patient with Crooke's cell carcinoma who presented with local invasion and liver metastases, which was refractory to conventional therapeutic modalities including transsphenoidal surgery, radiosurgery, medications, and hepatic transcatheter arterial embolization. After all these treatments failed, the patient had monthly temozolomide administrations, resulting in gradual clinical improvement and biochemical data that were consistent with tumor shrinkage. In glioblastoma, low O6-methylguanine DNA methyltransferase (MGMT) expression is associated with epigenetic gene silencing and predicts a better response to temozolomide.

Methods

We thus investigated MGMT expression, immunohistochemically, in seven CCAs (five invasive macroadenomas and two invasive microadenomas) and 17 ordinary-type adenomas (OTAs; three noninvasive macroadenomas, 12 noninvasive microadenomas, and two invasive microadenomas) from patients with Cushing's disease.

Results

In seven CCAs, all five invasive macroadenomas exhibited low MGMT expression, defined as <5% nuclear MGMT staining. In 17 OTAs, only one adenoma showed low MGMT expression.

Conclusion

In Cushing's disease, invasive macroadenomas including CCA usually have low-MGMT expression. Temozolomide thus may be a new therapeutic option for invasive macroadenomas such as CCA particularly when conventional treatments are ineffective.
RHO protein regulation of contraction in the human uterus
Authors: Lartey J , López Bernal A
Published: July 2009

The state of contraction in smooth muscle cells of the human uterus is dependent on the interaction of activated forms of actin and myosin. Ras homology (RHO) proteins are small monomeric GTP-binding proteins that regulate actin polymerisation and myosin phosphorylation in smooth muscle cells. Their action is determined by their level of expression, GTP-bound state, intracellular localisation and phosphorylated status. Agonist activated RHO proteins bind to effector kinases such as RHO kinase (ROCK) and diaphanous proteins (DIAPH) to regulate smooth muscle contraction by two mechanisms: ROCK activates smooth muscle myosin either by direct phosphorylation at Ser19/Thr18 or through inhibition of myosin phosphatase which is a trimeric protein regulated by ROCK and by other protein kinases. Actin-polymerising proteins such as DIAPH homolog 1 increase filamentous actin assembly to enhance acto-myosin cross bridge formation and contraction. This review explores recent advances in RHO protein signalling in human myometrium and proposes areas of further research to investigate the involvement of these proteins in the regulation of uterine contractility in pregnancy and labour.
Ovarian follicle development in Booroola sheep exhibiting impaired bone morphogenetic protein signalling pathway
Authors: Ruoss Chantelle , Tadros Amanda , O'Shea Tim , McFarlane Jim , Almahbobi Ghanim
Published: July 2009

The role of bone morphogenetic proteins (BMPs) in the regulation of ovarian function has been extensively investigated but the mechanism of regulation is not well understood. The aim of this study was to investigate the effect of mutation in the BMP receptor in Booroola sheep on the number of primordial follicles and rate of follicle recruitment in comparison with that in normal merino sheep in vivo. Whole sheep ovaries at the time of birth, 1.5 and 5 years old were collected and processed for the follicle quantification, using computerised stereological methods and statistical analyses. At birth, the total number of primordial follicles in Booroola sheep was significantly lower than in merino sheep. At 1.5 and 5 years, a reversed pattern in favour of Booroola ewes was seen with significantly more primordial follicles than merino. In parallel, the rate of primordial follicle recruitment to developing cohort was substantially lower in Booroola ewes with only 51 and 66% of primordial follicle consumption at 1.5 and 5 years respectively compared to 92 and 97% in merino ewes. On other hand, the mean numbers of developing primary follicles were smaller in Booroola sheep at the time of birth, yet, Booroola ewes possess more primary follicles than merino at 1.5 years. These findings suggest that attenuation of the intraovarian signalling pathway of BMPs may in fact be a successful means of rationalising follicle consumption, preventing unnecessary loss of follicles from the initial primordial follicle pool, hence increasing reproductive longevity and fertility.
Splicing Variation at a FLOWERING LOCUS C Homeolog Is Associated With Flowering Time Variation in the Tetraploid Capsella bursa-pastoris
Authors: Slotte Tanja , Huang Hui-Run , Holm Karl , Ceplitis Alf , Onge Kate St , Chen Jun , Lagercrantz Ulf , Lascoux Martin
Published: July 2009

The long-term fates of duplicate genes are well studied both empirically and theoretically, but how the short-term evolution of duplicate genes contributes to phenotypic variation is less well known. Here, we have studied the genetic basis of flowering time variation in the disomic tetraploid Capsella bursa-pastoris. We sequenced four duplicate candidate genes for flowering time and 10 background loci in samples from western Eurasia and China. Using a mixed-model approach that accounts for population structure, we found that polymorphisms at one homeolog of two candidate genes, FLOWERING LOCUS C (FLC) and CRYPTOCHROME1 (CRY1), were associated with natural flowering time variation. No potentially causative polymorphisms were found in the coding region of CRY1; however, at FLC two splice site polymorphisms were associated with early flowering. Accessions harboring nonconsensus splice sites expressed an alternatively spliced transcript or did not express this FLC homeolog. Our results are consistent with the function of FLC as a major repressor of flowering in Arabidopsis thaliana and imply that nonfunctionalization of duplicate genes could provide an important source of phenotypic variation.
Specific Genetic Interactions Between Spindle Assembly Checkpoint Proteins and B-Type Cyclins in Saccharomyces cerevisiae
Authors: Ikui Amy E , Cross Frederick R
Published: July 2009

The B-type cyclin Clb5 is involved primarily in control of DNA replication in Saccharomyces cerevisiae. We conducted a synthetic genetic array (SGA) analysis, testing for synthetic lethality between the clb5 deletion and a selected 87 deletions related to diverse aspects of cell cycle control based on GO annotations. Deletion of the spindle checkpoint genes BUB1 and BUB3 caused synthetic lethality with clb5. The spindle checkpoint monitors the attachment of spindles to the kinetochore or spindle tension during early mitosis. However, another spindle checkpoint gene, MAD2, could be deleted without ill effects in the absence of CLB5, suggesting that the bub1/3 clb5 synthetic lethality reflected some function other than the spindle checkpoint of Bub1 and Bub3. To characterize the lethality of bub3 clb5 cells, we constructed a temperature-sensitive clb5 allele. At nonpermissive temperature, bub3 clb5-ts cells showed defects in spindle elongation and cytokinesis. High-copy plasmid suppression of bub3 clb5 lethality identified the C-terminal fragment of BIR1, the yeast homolog of survivin; cytologically, the BIR1 fragment rescued the growth and cytokinesis defects. Bir1 interacts with IplI (Aurora B homolog), and the addition of bub3 clb5-ts significantly enhanced the lethality of the temperature-sensitive ipl1-321. Overall, we conclude that the synthetic lethality between clb5 and bub1 or bub3 is likely related to functions of Bub1/3 unrelated to their spindle checkpoint function. We tested requirements for other B-type cyclins in the absence of spindle checkpoint components. In the absence of the related CLB3 and CLB4 cyclins, the spindle integrity checkpoint becomes essential, since bub3 or mad2 deletion is lethal in a clb3 clb4 background. clb3 clb4 mad2 cells accumulated with unseparated spindle pole bodies. Thus, different B-type cyclins are required for distinct aspects of spindle morphogenesis and function, as revealed by differential genetic interactions with spindle checkpoint components.
Phase 1 Trial of 4 Thyroid Hormone Regimens for Transient Hypothyroxinemia in Neonates of <28 Weeks' Gestation
Authors: La Gamma Edmund F. , van Wassenaer Aleid G. , Ares Susana , Golombek Sergio G. , Kok Joke H. , Quero Jose , Hong Ting , Rahbar Mohammad H. , de Escobar Gabriella Morreale , Fisher Delbert A. , Paneth Nigel
Published: July 2009

BACKGROUND: Transiently low levels of thyroid hormones occur in ∼50% of neonates born 24–28 weeks' gestation and are associated with higher rates of cerebral palsy and cognitive impairment. Raising hormone levels shows promise for improving neurodevelopmental outcome.

OBJECTIVE: To identify whether any of 4 thyroid hormone supplementation regimens could raise T4 and FT4 without suppressing TSH (biochemical euthyroidism).

METHODS: Eligible subjects had gestational ages between 24\batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \({0}/{7}\) \end{document} and 27\batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \({6}/{7}\) \end{document} weeks and were randomized <24 hours of birth to one of six study arms (n = 20–27 per arm): placebo (vehicle: 5% dextrose), potassium iodide (30 μg/kg/d) and continuous or bolus daily infusions of either 4 or 8 μg/kg/d of T4 for 42 days. T4 was accompanied by 1 μg/kg/d T3 during the first 14 postnatal days and infused with 1 mg/mL albumin to prevent adherence to plastic tubing.

RESULTS: FT4 was elevated in the first 7 days in all hormone-treated subjects; however, only the continuous 8 μg/kg/d treatment arm showed a significant elevation in all treatment epochs (P < .002 versus all other groups). TT4 remained elevated in the first 7 days in all hormone-treated subjects (P < .05 versus placebo or iodine arms). After 14 days, both 8 μg/kg/d arms as well as the continuous 4 μg/kg/d arm produced a sustained elevation of the mean and median TT4, >7 μg/dL (90 nM/L; P < .002 versus placebo). The least suppression of THS was achieved in the 4 μg/kg/d T4 continuous infusion arm. Although not pre-hypothesized, the duration of mechanical ventilation was significantly lower in the continuous 4 μg/kg/d T4 arm and in the 8 μg/kg/d T4 bolus arm (P < .05 versus remaining arms). ROP was significantly lower in the combined 4 thyroid hormone treatment arms than in the combined placebo and iodine arms (P < .04). NEC was higher in the combined 8 μg/kg/d arms (P < .05 versus other arms).

CONCLUSIONS: Elevation of TT4 with only modest suppression of TSH was associated with trends suggesting clinical benefits using a continuous supplement of low-dose thyroid hormone (4 μg/kg/d) for 42 days. Future trials will be needed to assess the long-term neurodevelopmental effects of such supplementation.
Fundamental Mechanisms of Copper CMP – Passivation Kinetics of Copper in CMP Slurry Constituents
Authors: Tripathi Shantanu , Doyle Fiona M. , Dornfeld David A.
Published: July 2009

During copper CMP, abrasives and asperities interact with the copper at the nano-scale, partially removing protective films. The local Cu oxidation rate increases, then decays with time as the protective film reforms. In order to estimate the copper removal rate and other Cu-CMP output parameters with a mechanistic model, the passivation kinetics of Cu, i.e. the decay of the oxidation current with time after an abrasive/copper interaction, are needed. For the first time in studying Cu-CMP, microelectrodes were used to reduce interference from capacitive charging, IR drops and low diffusion limited currents, problems typical with traditional macroelectrodes. Electrochemical impedance spectroscopy (EIS) was used to obtain the equivalent circuit elements associated with different electrochemical phenomena (capacitive, kinetics, diffusion etc.) at different polarization potentials. These circuit elements were used to interpret potential-step chronoamperometry results in inhibiting and passivating solutions, notably to distinguish between capacitive charging and Faradaic currents.

Chronoamperometry of Cu in acidic aqueous glycine solution containing the corrosion inhibitor benzotriazole (BTA) displayed a very consistent current decay behavior at all potentials, indicating that the rate of current decay was controlled by diffusion of BTA to the surface. In basic aqueous glycine solution, Cu (which undergoes passivation by a mechanism similar to that operating in weakly acidic hydrogen peroxide slurries) displayed similar chronoamperometric behavior for the first second or so at all anodic potentials. Thereafter, the current densities at active potentials settled to values around those expected from polarization curves, whereas the current densities at passive potentials continued to decline. Oxidized Cu species typically formed at ‘active’ potentials were found to cause significant current decay at active potentials and at passive potentials before more protective passive films form. This was established from galvanostatic experiments.
Thermoelectric Properties of Nb-Doped SrTiO3 / TiO2 Multiphase Composite
Authors: Fuda Kiyoshi , Murakami Kenji , Shoji Tomoyoshi , Sugiyama Shigeaki
Published: July 2009

In this study, we fabricated and examined a series of multiphase type composites constructed of Nb-doped SrTiO3 / TiO2 fine particles. The composition of the composites and the sintering temperatures were selected in a two-phase region where a perovskite SrTiO3 and a rutile TiO2 phases coexist. The composites obtained here were found to commonly have a mosaic type texture constructed of TiO2 and SrTiO3 fine particles with a typical size of about 500 nm. In some samples we also found additive phases such as Sr6Ti7Nb9O42. The thermal conductivity values measured for the most samples with different contents are ranged between 2 and 5 Wm-1K-1. The values are apparently lower than the value for single crystal SrTiO3 samples presented in literature. A sample with rather low relative density of about 80% showed a quite low thermal conductivity, about 1 Wm-1K-1. Taking account the other TE data, e.g. Seebeck coefficient and electrical conductivity, we calculated dimensionless figure of merit, ZT, to be at maximum 0.24 at 600°C.
Spin Polarization of Electrons Injected from Fe into GaAs Quantum Well Characterized using Oblique Hanle Effect
Authors: Wada Eiji , Itoh Mitsuru , Taniyama Tomoyasu , Yamaguchi Masahito
Published: July 2009

We study spin injection from an in-plane magnetized Fe thin layer into a GaAs/AlGaAs quantum well (QW) in low magnetic fields of ±0.37 T using oblique Hanle effect. An oblique low magnetic field induces the precession of electron spins in the GaAs QW, allowing us to detect the spin polarization of electrons injected across the Fe/AlGaAs interface. Our analysis of the circular polarization of light emitted in the electron-hole recombination process in the QW gives an estimate of the lower bounds of the spin polarization to be 4.0%. Also, a spin lifetime of 140 psec is obtained in this analysis, indicating that spin depolarization at the Fe/AlGaAs interface is more predominant rather than spin relaxation in the QW region.
Functional Fatigue of Shape-Memory Polymers
Authors: Schmidt Christina , Neuking Klaus , Eggeler Gunther
Published: July 2009

The present study represents a first step towards an understanding of what we refer to as the functional fatigue behaviour of shape-memory polymers. These materials have a processing shape B and a programmed shape A [1]. And when the material is exposed to an appropriate stimulus (in our case: heating above a critical temperature), a one way effect is observed: A → B (one way effect: 1WE). The objectives of the present study were to find out whether and how often programming can be repeated, whether repeated programming affects the 1WE and how much irreversible strain the material accumulates. We study the effect in dependence of different stress levels, and consider the effect of recovery temperature and recovery time. As a model material we examine the commercial amorphous shape-memory polymer Tecoflex® and subject it to 50 programming/1WE cycles. It turns out that programming, cooling, unloading and heating to trigger the 1WE causes an increase of irreversible strain and is associated with a corresponding decrease of the intensity of the 1WE in particular during the first thermomechanical cycles.

1. M. Behl and A. Lendlein, materials today 10, 20 (2007).
Phase Behavior and Shrinking Kinetics of Thermo-Reversible Poly(N-Isopropylacrylamide-2-Hydroxyethyl Methacrylate)
Authors: Leon Christine M , Solis Francisco J , Vernon Brent L
Published: July 2009

We study the thermodynamic properties of solutions of the physically gelling poly(N-isopropylacrylamide-2-hydroxyethyl methacrylate) [poly(NIPPAm-HEMA)]. We construct its phase diagram and characterize its kinetics of phase separation. This material belongs to a class of thermosensitive, “smart” polymers, that exhibit complex phase behavior.
The copolymer studied is liquid at low temperatures and undergoes phase separation near 28°C, with negligible dependence on concentration. Above the transition temperature we observe coexistence between a polymer-dilute solution and a gel. We show that, upon quick heating, liquid solutions form a homogeneous gel that phase separates (shrinks) from a dilute polymer solution. We find that the evolution of the gel volume fraction is well described by a double exponential decay, indicating the presence of two shrinking regimes in a close parallel to the behavior of chemically cross-linked gels. The first stage is characterized by quick water ejection. In the second stage, slower shrinking is observed associated with internal reorganization of the polymers that allows the creation of gel-forming contacts.
Schizophrenic Molecules and Materials with Multiple Personalities - How Materials Science could Revolutionise How we do Chemical Sensing
Authors: Byrne Robert , Scarmagnani Silvia , Radu Alex , Benito-Lopez Fernando , Diamond Dermot
Published: July 2009

Molecular photoswitches like spiropyrans derivatives offer exciting possibilities for the development of analytical platforms incorporating photo-responsive materials for functions such as light-activated guest uptake and release and optical reporting on status (passive form, free active form, guest bound to active form). In particular, these switchable materials hold tremendous promise for microflow-systems, in view of the fact that their behaviour can be controlled and interrogated remotely using light from LEDs, without the need for direct physical contact. We demonstrate the immobilisation of these materials on microbeads which can be incorporated into a microflow system to facilitate photoswitchable guest uptake and release. We also introduce novel hybrid materials based on spiropyrans derivatives grafted onto a polymer backbone which, in the presence of an ionic liquid, produces a gel-like material capable of significant photoactuation behaviour. We demonstrate how this material can be incorporated into microfluidic platforms to produce valve-like structures capable of controlling liquid movement using light.
Modelagem e simulação distribuída de sistema produtivo baseados em rede de Petri
Authors: Junqueira Fabrício , Miyagi Paulo Eigi
Published: July 2009

Em função da capacidade computacional instalada e da estrutura dispersa de alguns sistemas produtivos, existe interesse em soluções de modelagem e simulação distribuída destes sistemas. Isso é considerado como um recurso fundamental para o projeto, implementação e melhoria de desempenho desses sistemas produtivos. A idéia é que por meio de simulações com o uso de computadores fisicamente dispersos, mas integrados através de uma rede de comunicação, pode-se avaliar o comportamento de sistemas em concepção e melhorar resultados de plantas existentes. Este trabalho propõe assim, um procedimento para a modelagem de sistemas produtivos em ambientes distribuídos. Esse procedimento foi aplicado com sucesso a alguns estudos de caso onde sua eficácia foi confirmada. Este trabalho envolve ainda a proposta de um algoritmo para o gerenciamento da simulação distribuída. Com o método de modelagem e o algoritmo de gerenciamento tem-se os principais elementos para a implementação prática de um simulador de sistemas produtivos dispersos.
Controlador em modo dual adaptativo robusto para plantas com grau relativo arbitrário
Authors: Cunha Caio D. , Araújo Aldayr D. , Mota Francisco C.
Published: July 2009

Neste artigo é apresentado o Controlador em Modo Dual Adaptativo Robusto (DMARC). O DMARC é um sistema de controle que combina as estratégias de Controle Adaptativo por Modelo de Referência (MRAC) com leis integrais de adaptação e o Controle Adaptativo por Modelo de Referência e Estrutura Variável (VS-MRAC) com leis chaveadas de acordo com a teoria de sistemas com estrutura variável. A idéia básica é incorporar as vantagens de desempenho transitório de um VS-MRAC, com as propriedades de regime permanente de um MRAC convencional. Desta forma, obtém-se um sistema de controle robusto a incertezas paramétricas e perturbações externas, com desempenho rápido e pouco oscilatório durante o transitório e um sinal de controle suave em regime permanente.
Human aortic smooth muscle cells are insulin resistant at the receptor level but sensitive to IGF1 and IGF2
Authors: Chisalita S I , Johansson G S , Liefvendahl E , Bäck K , Arnqvist H J
Published: July 2009

Whether insulin, at physiological concentrations, has direct effects on vascular smooth muscle cells (VSMCs) remains controversial. Our aim was to characterize the mechanism for insulin resistance in VSMCs. For comparison, the effects of IGF1 and IGF2 were also studied. Cultured human aortic smooth muscle cells (HASMC) were used. Receptor mRNA was analyzed by quantitative reverse transcription PCR and receptor protein by ELISA and western blot. Biological effects were studied by thymidine incorporation and glucose accumulation. In HASMC, both mRNA and protein expression of IGF1 receptors (IGF1R) were fivefold higher compared to insulin receptor (IR). IR isoform A mRNA was 13-fold more expressed than IR isoform B. IR and IGF1R co-precipitated, indicating the presence of hybrid IR/IGF1R. Phosphorylation of the IGF1R β-subunit was obtained by IGF1 10−9–10−8 mol/l and IGF2 10−8 mol/l. IR β-subunit was phosphorylated by IGF1 10−8 mol/l but not by insulin. IGF1 stimulated IR substrate-1 and AKT at 10−8 mol/l and extracellular signal-regulated kinases 1 and 2 at 10−9–10−8 mol/l respectively. IGF1 and 2 at a concentration of 10−8–10−7 mol/l significantly stimulated 3H-thymidine incorporation, whereas insulin did not. 14C-Glucose accumulation was stimulated by IGF1 or IGF2 10−8–10−7 mol/l, and also by insulin 10−7 mol/l. Our results suggest that IGF1R and hybrid IR/IGF1R are activated by physiological concentrations of IGF1 and 2 in HASMC and this propagates downstream signaling and biological effects, while insulin has no effect on its receptor or downstream signaling probably due to a preponderance of IGF1R and incorporation of IR into hybrid IR/IGF1R.
CO2, nitrogen, and diversity differentially affect seed production of prairie plants
Authors: HilleRisLambers J. , Harpole W. S. , Schnitzer S. , Tilman D. , Reich P. B.
Published: July 2009

Plant species composition and diversity is often influenced by early life history stages; thus, global change could dramatically affect plant community structure by altering seed production. Unfortunately, plant reproductive responses to global change are rarely studied in field settings, making it difficult to assess this possibility. To address this issue, we quantified the effects of elevated CO2, nitrogen deposition, and declining diversity on inflorescence production and inflorescence mass of 11 perennial grassland species in central Minnesota, USA. We analyzed these data to ask whether (1) global change differentially affects seed production of co‐occurring species; (2) seed production responses to global change are similar for species within the same functional group (defined by ecophysiology and growth form); and (3) seed production responses to global change match productivity responses. We found that, on average, allocation to seed production decreased under elevated CO2, although individual species responses were rarely significant due to low power (CO2 treatment df = 2). The effects of nitrogen deposition on seed production were similar within functional groups: C4 grasses tended to increase while C3 grasses tended to decrease allocation to seed production. Responses to nitrogen deposition were negatively correlated to productivity responses, suggesting a trade‐off. Allocation to seed production of some species responded to a diversity gradient, but responses were uncorrelated to productivity responses and not similar within functional groups. Presumably, species richness has complex effects on the biotic and abiotic variables that influence seed production. In total, our results suggest that seed production of co‐occurring species will be altered by global change, which may affect plant communities in unpredictable ways. Although functional groups could be used to generalize seed production responses to nitrogen deposition in Minnesota prairies, we caution against relying on them for predictive purposes without a mechanistic understanding of how resource availability and biotic interactions affect seed production.
Tree species fine‐root demography parallels habitat specialization across a sandhill soil resource gradient
Authors: Espeleta Javier F. , West Jason B. , Donovan Lisa A.
Published: July 2009

Single species can substantially alter belowground processes in ecosystems via differential root production and death. However, information on species differences in fine‐root demography is virtually absent for natural communities. In this field study, we recorded species‐specific fine‐root (<2 mm in diameter) demography in adults of four tree species (Pinus palustris,Quercus laevis,Q. incana, andQ. margaretta) that are distributed differentially along soil resource gradients in the fall‐line sandhills of the southeastern United States. At a subxeric habitat where all four species co‐occur, roots of individual trees of each species were isolated in rhizotrons and tracked individually for three years.Quercusspecies had similar fine‐root morphology but differed substantially for fine‐root demography and architecture.Quercus laevisandQ. incana, the species from xeric habitats, showed lower fine‐root production, death, percentage mortality, turnover rates, and risk of death, and greater life span and mean root segment length (MRSL) thanQ. margaretta, the species from subxeric habitats. Fine roots ofP. palustris(a generalist) showed high production and intermediate mortality, turnover rate, longevity, and MRSL. Fine‐root survival increased with root order (first to fourth in centripetal order), but the degree of change was species specific.Q. margarettashowed greater increases in survival with order, but all species had similar demography of third‐ and fourth‐order roots. Mycorrhizal roots had greater longevity than non‐mycorrhizal roots only inQ. laevis. Species differences were also seasonal. Although theseQuercusspecies are leaf deciduous, some growth of fine roots occurred inQ. margarettaduring the “leaf‐dormant” season. In our narrow‐scale species comparison, species differences in ecological distribution were consistent with the observed variation in fine‐root demography and architecture with greater resolution than leaf characters or other root traits such as morphology. Our results also show that narrow‐scale variation in fine‐root demography (including intra‐generic differences) can be as large as broad‐scale variation across biomes and vegetation types. Hence, small shifts in community composition have the potential to produce substantial changes below ground.
Population dynamics of two sympatric rodents in a variable environment: rainfall, resource availability, and predation
Authors: Previtali M. Andrea , Lima Mauricio , Meserve Peter L. , Kelt Douglas A. , Gutiérrez Julio R.
Published: July 2009

Precipitation plays an important role in the dynamics of species found in arid and semiarid environments. However, population fluctuations generally are driven by a combination of multiple factors whose relative contribution may vary through time and among species. We monitored fluctuations of species in three trophic levels for >17 years at a semiarid community in north‐central Chile. The region is strongly affected by the El Niño Southern Oscillation, resulting in high variation in rainfall that triggers dramatic changes in food resource availability, with strong effects on upper trophic levels. We focused our analyses on the role played by endogenous and exogenous (climatic) factors on the dynamics of two important rodent species in the community, Octodon degus and Phyllotis darwini. We documented population fluctuations of several orders of magnitude in response to wet and dry episodes of different strength and duration. P. darwini reached similar maximum densities, regardless of the duration of high‐rainfall events, whereas O. degus showed additive effects of multiple wet years. Time series diagnostic tools revealed oscillations with a 5‐year periodicity in rainfall, which may be the cause of the same periodicity and a weak second‐order signal observed in the rodent dynamics. However, the dynamics of both rodent species were dominated by strong first‐order processes, suggesting an important role of direct density dependence. Intraspecific competition, expressed as the ratio of rodent density/rainfall (or food resources) explained more than two‐thirds of the variation in the population rate of change, whereas less than one‐third was explained by lagged rainfall (or food resources). We detected no significant effects of predation. Our results contribute to a growing number of examples of dynamics governed by the combined effect of density dependence and climatic forcing. They also reveal strong bottom‐up regulation that may be common in other arid environments.
Individual quality, early‐life conditions, and reproductive success in contrasted populations of large herbivores
Authors: Hamel Sandra , Gaillard Jean-Michel , Festa-Bianchet Marco , Côté Steeve D.
Published: July 2009

Variations among individuals in phenotypic quality and fitness often confound analyses of life‐history strategies assessed at the population level. We used detailed long‐term data from three populations of large herbivores with generation times ranging from four to nine years to quantify heterogeneity in individual quality among females, and to assess its influence on mean annual reproductive success over the lifetime (MRS). We also determined how environmental conditions in early life shaped individual quality and tested A. Lomnicki's hypothesis that variance in individual quality should increase when environmental conditions deteriorate. Using multivariate analyses (PCA), we identified one (in sheep and deer) or two (in goats) covariations among life‐history traits (longevity, success in the last breeding opportunity, adult mass, and social rank) as indexes of individual quality that positively influenced MRS of females. Individual quality was reduced by unfavorable weather, low resource availability, and high population density in the year of birth. Early‐life conditions accounted for 35–55% of variation in individual quality. In roe deer, we found greater variance in individual quality for cohorts born under unfavorable conditions as opposed to favorable ones, but the opposite was found in bighorn sheep and mountain goats. Our results demonstrate that heterogeneity in female quality can originate from environmental conditions in early life and can markedly influence the fitness of females in species located at different positions along the slow–fast continuum of life‐history strategies.
Elevated pH regulates bacterial carbon cycling in lakes with high photosynthetic activity
Authors: Tank Suzanne E. , Lesack Lance F. W. , McQueen Donald J.
Published: July 2009

Bacteria are critically important for carbon (C) cycling and energy flow in aquatic environments. However, studies to date have largely focused on the role of substrate quality in the regulation of this important process. As such, we know little about the role of other ecological drivers in shaping bacterially mediated C cycling. Here we examine the manner in which planktonic bacterial abundance (BA), productivity (BP), respiration (BR), and growth efficiency (BGE), and thus C cycling are affected by elevated pH, an ecological factor that occurs commonly in highly productive aquatic systems. We undertook our study in lakes of the Mackenzie Delta region of Canada. These lakes routinely experience high pH caused by rapid macrophyte photosynthesis. Two different experiment types were employed: first, a series of short‐term experiments was used to assess the direct effects of elevated pH on bacteria experiencing differing pH levels in situ. Second, long‐term mesocosms were used to explore the effect of elevated pH on bacteria over longer time scales and in the presence of other trophic levels. Bacterial productivity and BR slowed dramatically with elevated pH over the short term, potentially uncoupling bacterial processing of organic matter from its in‐lake production and causing a switch away from biomass creation and toward C mineralization. With longer term exposure, bacterial communities adapted to the direct stress of elevated pH, but responses at higher trophic levels caused a cascade that mediated the effect of alkalization on bacteria, in a manner that could well vary among aquatic ecosystems. Our study establishes elevated pH as a key driver of bacterial C cycling and energy flow in aquatic systems with high autotrophic productivity.
Host resistance reverses the outcome of competition between microparasites
Authors: Gruner Daniel S. , Kolekar Arunima , McLaughlin John P. , Strong Donald R.
Published: July 2009

Predators and parasites can control the abundance or biomass of herbivores with indirect effects on producer communities and ecosystems, but the interplay of multiple natural enemies may yield unexpected dynamics. We experimentally examined interactions between two microparasites (entomopathogenic nematodes) isolated from sandy grassland soils of coastal California: Heterorhabditis marelatus (Heterorhabditidae) and Steinernema feltiae (Steinernematidae). Heterorhabditis marelatus drives trophic cascades by attacking root‐ and stem‐boring ghost moth caterpillars (Hepialus californicus, Hepialidae), thereby indirectly protecting bush lupine shrubs (Lupinus arboreus, Fabaceae). Extensive field surveys demonstrated sympatric overlap in microhabitat use under lupine canopies and similar mean prevalence of the two nematode species. Using a response‐surface design in the laboratory, we varied relative and absolute microparasite densities to test for competitive outcomes within an evolutionary naïve host, larvae of the greater wax moth Galleria mellonella (Pyralidae), and within the native host Hepialus californicus. Independent of conspecific or interspecific density, S. feltiae dominated as expected over H. marelatus within the naïve Galleria, but S. feltiae infected hosts at low frequency and showed lower reproductive fitness than H. marelatus within native Hepialus hosts. Contrary to studies that demonstrate the pairwise dominance of steinernematid over heterorhabditid species in laboratory hosts, host resistance to S. feltiae may provide a mechanism for coexistence of multiple microparasite species. We hypothesize that the ubiquitous field prevalence and rapid life history of S. feltiae imply its use of widespread, abundant but small‐bodied hosts and indicate the lack of direct competition with H. marelatus in the Hepialus–Lupinus trophic cascade.
Model complexity affects transient population dynamics following a dispersal event: a case study with pea aphids
Authors: Tenhumberg Brigitte , Tyre Andrew J. , Rebarber Richard
Published: July 2009

Stage‐structured population models predict transient population dynamics if the population deviates from the stable stage distribution. Ecologists' interest in transient dynamics is growing because populations regularly deviate from the stable stage distribution, which can lead to transient dynamics that differ significantly from the stable stage dynamics. Because the structure of a population matrix (i.e., the number of life‐history stages) can influence the predicted scale of the deviation, we explored the effect of matrix size on predicted transient dynamics and the resulting amplification of population size. First, we experimentally measured the transition rates between the different life‐history stages and the adult fecundity and survival of the aphid, Acythosiphon pisum. Second, we used these data to parameterize models with different numbers of stages. Third, we compared model predictions with empirically measured transient population growth following the introduction of a single adult aphid. We find that the models with the largest number of life‐history stages predicted the largest transient population growth rates, but in all models there was a considerable discrepancy between predicted and empirically measured transient peaks and a dramatic underestimation of final population sizes. For instance, the mean population size after 20 days was 2394 aphids compared to the highest predicted population size of 531 aphids; the predicted asymptotic growth rate (λmax) was consistent with the experiments. Possible explanations for this discrepancy are discussed.
Measurement of Soil Bulk Electrical Conductivity Using Partially Coated TDR Probes
Authors: Moret-Fernández D. , Lera F. , Arrúe J. L. , López M. V.
Published: July 2009

The time domain reflectometry (TDR) technique allows simultaneous estimation of apparent permittivity (εa) and bulk electrical conductivity (σa). In highly conductive media, however, the signal is completely attenuated, which precludes permittivity measurements. This study showed that σa can be estimated in conductive media by applying long‐time TDR waveform analysis to a TDR probe partially insulated with a high‐dielectric coating. Four 10‐cm‐long three‐rod TDR probes with identical geometry but different percentages of rod coating were tested: an uncoated sensor (P0) and probes with 50% (P50), 75% (P75), and 95% (P95) of the rod length coated with an insulator with a relative permittivity (εr) of 32.3. A good relationship (r2 = 0.99) was found between the εa estimated, if possible, with P0 immersed in several conductive and nonconductive media and the corresponding values estimated with P50, P75, and P95 The results also show that, for σa values ranging between 0.4 and 0.75 S m−1, simultaneous measurements of εa and σa were only possible using the partially coated probes. A good correlation was found between the σa estimated with P0 inserted in different soil columns wetted with highly saline solutions (i.e., σa > 0.2 S m−1) and those values estimated with P50, P75, and P95 (r2 = 0.96, RMSE = 1.08, and SD = 0.38). For σa < 0.2 S m−1, the accuracy of the partially coated TDR probes for estimations of σa decreased as the percentage of the rod coating increased, with errors up to 292% when σa determined by P95 was compared with that estimated by P0
Molecular detection of enterotoxins in environmental strains of Aeromonas hydrophila and Aeromonas jandaei
Authors: Balsalobre L. C. , Dropa M. , Matté G. R. , Matté M. H.
Published: July 2009

Aeromonas species are widely distributed in aquatic environments and recent studies include the genus in the emergent pathogens group because of its frequent association with local and systemic infections in immunocompetent humans. Aiming to search for virulence genes in environmental strains of Aeromonas hydrophila and Aeromonas jandaei, we designed specific primers to detect act/hly A/aer complex and alt genes. Primers described elsewhere were used to detect ast. Eighty-seven strains previously identified using phenotypic and genotypic tests as A. hydrophila (41) and A. jandaei (46) were analysed for the presence of the virulence genes using PCR. DNA fragments of expected size were purified and directly sequenced. Among the 41 strains of A. hydrophila 70.7% (29), 97.6% (40) and 26.8% (11) possessed act/hly A/aer complex, ast and alt genes, respectively. Among the 46 strains of A. jandaei, 4.4% (2), 0% (0) and 32.6% (15) were positive for act/hly A/aer complex, ast and alt genes, respectively. Sequencing allowed for the confirmation of amplified products using BLAST. The present work proposes a specific and rapid diagnostic method to detect the main virulence determinants of Aeromonas, a genus potentially pathogenic to humans.
Quantifying the burden of disease associated with inadequate provision of water and sanitation in selected sub-Saharan refugee camps
Authors: Cronin Aidan A. , Shrestha Dinesh , Spiegel Paul , Gore Fiona , Hering Heiko
Published: July 2009

A WHO methodology is used for the first time to estimate the burden of disease directly associated with incomplete water and sanitation provision in refugee camps in sub-Saharan African countries. In refugee camps of seven countries, containing just fewer than 1 million people in 2005, there were 132,000 cases of diarrhoea and over 280,000 reported cases of malaria attributable to incomplete water and sanitation provision. In the period from 2005 to 2007 1,400 deaths were estimated to be directly attributable to incomplete water and sanitation alone in refugee camps in Ethiopia, Kenya and Tanzania. A comparison with national morbidity estimates from WHO shows that although diarrhoea estimates in the camps are often higher, mortality estimates are generally much lower, which may reflect on more ready access to medical aid within refugee camps. Despite the many limitations, these estimates highlight the burden of disease connected to incomplete water and sanitation provision in refugee settings and can assist resource managers to identify camps requiring specific interventions. Additionally the results reinforce the importance of increasing dialogue between the water, sanitation and health sectors and underline the fact that efforts to reduce refugee morbidity would be greatly enhanced by strengthening water and sanitation provision.
Bactericidal activity of Ag nanoparticle-impregnated fibreglass for water disinfection
Authors: Nangmenyi Gordon , Xao Wei , Mehrabi Sharifeh , Mintz Eric , Economy James
Published: July 2009

A new bactericidal system composed of fibreglass impregnated with silver (Ag) nanoparticles was developed and tested. Silver content, particle size and distribution were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The antibacterial effectiveness was evaluated against Escherichia coli (E. coli, ATCC 29055). The minimum inhibitory loading was determined to be less than 1.8 wt% of silver nanoparticles per gram of fibreglass. In a 1 h immersion test, using a 0.1 mg fibreglass mat ml−1, with 2.9 wt% loading of silver nanoparticles completely disinfected 100 ml of 106 CFU ml−1 of E. coli, dramatically outperforming activated carbon fibres impregnated with silver. Inactivation rate studies of 0.05 mg fibreglass mat ml−1 (Ag 1.8 wt%) with 1012 CFU E. coli displayed a 7 log reduction in 5 minutes. The activation and reuse of fibreglass (Ag 4.3 wt%) maintained its full effectiveness after two cycles of use and thermal regeneration at 350°C.
Trickle-Bed Laboratory Reactors for Kinetic Studies
Authors: Mary Gaetan , Chaouki Jamal , Luck Francis
Published: July 2009

In this paper, different phenomena affecting laboratory trickle-bed reactors are carefully reviewed. Before focusing on laboratory scale, some general considerations about trickle-bed reactors are discussed: regimes, industrial uses, etc. The main factors a laboratory trickle bed reactors are presented and detailed. The greatest six factors include: homogeneity of the catalyst bed, catalyst wetting, axial dispersion, channeling, isothermicity and mass transfer. These factors are reviewed and different criteria, suggested in the literature, are given in order to minimize the influence of these six factors; for each criterion, a simple application is presented. Finally, the application of all the criteria given in the paper is based on a hypothetical example (hydrodesulfurization).