JOURNAL OF PHYCOLOGY, Issue 2000
M. L. Berndt
The reproductive success of marine species with external fertilization depends on environmental conditions during gamete release. There is special interest presently in whether water motion causes sperm limitation under natural conditions. We investigated gamete release of Fucus vesiculosus from an exposed shore to ascertain: 1) when gametes are released during the tidal cycle, 2) when fertilization occurs, and 3) what the natural sperm:egg ratios are. Water samples were collected and concentrated over five minutes every half hour off Pemaquid Point, ME from three replicate sites within each of two locations using a pump-filter device. Immunofluorescence microscopy revealed that gamete release occurred only on the two calmest spring tides. Sperm became present in the water column at the same time as oogonia (30 min,1 h prior to high tide [HT]) and reached peak concentration at exactly HT. The sperm:egg ratio was 76:1 on 8 Oct 1999 and 21:1 on 8 Nov 1999 at exactly 30 min prior to HT and dropped sharply after HT. Gametes continued to be collected for several hours after HT but analysis of pronuclear position in aceto-iron-hematoxylin stained eggs revealed that all fertilization occurred at approximately HT. We modelled the total number of days when reproduction was possible using these results and wind and wave data from the National Data Buoy Center. Our research provides evidence that gamete release by F. vesiculosus occurs at slack HT on calm days and that sperm are not a limiting factor in fertilization for this species. [source]

Limiting light-induced lipid peroxidation and vitamin loss in infant parenteral nutrition by adding multivitamin preparations to Intralipid

ACTA PAEDIATRICA, Issue 3 2001
KM Silvers
Parenteral lipids are susceptible to light-induced peroxidation, particularly under phototherapy. Ascorbic acid is protective. The aim of this study was to investigate whether dark delivery tubing and/or coadministration of multivitamin preparations could prevent peroxidation of Intralipid without undue vitamin loss. In experiments carried out on the benchtop, lipid peroxidation occurred in ambient light and was more extensive under phototherapy. Dark tubing decreased peroxide formation, but only by about 65%. In simulated clinical conditions in which solutions were pumped through standard clear or dark minibore plastic tubing, Intralipid accumulated lipid peroxides as measured by the FOX assay (280 ,M) or as triglyceride hydroperoxides (52 ,M). Multivitamin preparations (MVIP or Soluvit/Vitlipid) inhibited peroxide formation almost completely, and were fully protective when used with dark tubing. There was loss of riboflavin (65% from Soluvit and 35% from MVIP) in clear tubing but this was decreased to 18% and 11%, respectively, in dark tubing. Ascorbate loss was 20% (MVIP) and 50% (Soluvit) and only slightly less in dark tubing. Ascorbate loss was also seen in the absence of Intralipid and is due to riboflavin-induced photo-oxidation. Conclusion: Multivitamin preparations protect Intralipid against light-induced formation of lipid hydroperoxides, and administering multivitamins with Intralipid via dark delivery tubing provides a practical way of preventing peroxidation of the lipid while limiting vitamin loss. This procedure should be considered for routine use as well as with phototherapy. [source]

Strong Optical Limiting of Soluble Axially Substituted Gallium and Indium Phthalocyanines,

ADVANCED MATERIALS, Issue 11 2003
Y. Chen
Optical limiting in In- and Ga-phthalocyanines exhibits a range of saturation densities and absorption cross-section ratios. Substitution of the p -trifluoromethylphenyl group at the central metal in tBu4PcGaCl and tBu4PcInCl reduces the saturation energy density by a factor of >3. Tailorable optical limiting properties are shown in the Figure, which plots the nonlinear absorption coefficient as a function of intensity for the five compounds studied. [source]

Factors Limiting the Efficacy of Hydrogen Peroxide Washes for Decontamination of Apples Containing Escherichia coli

JOURNAL OF FOOD SCIENCE, Issue 3 2000
G.M. Sapers
ABSTRACT: Factors limiting efficacy of H2O2 washes and alternative decontamination strategies were investigated with Golden Delicious apples, inoculated with nonpathogenic Escherichia coli. Post-treatment rinsing decreased efficacy by eliminating residual H2O2. A 2-stage wash incorporating a rinse to remove surfactant residues prior to H2O2 application was developed. Rapid attachment of E. coli to apples prevented effective removal by washing with water. Surviving E. coli following a 5% H2O2 wash were concentrated in stem and calyx areas. Survival was independent of the time interval between inoculation and washing. E. coli inoculation of punctured apple surfaces resulted in growth at 20 °C and greater survival after washing with 5% H2O2. Improved decontamination methods are needed. [source]

Progress in rational methods of cryoprotection in macromolecular crystallography

ACTA CRYSTALLOGRAPHICA SECTION D, Issue 4 2010
Thomas Alcorn
Cryogenic cooling of macromolecular crystals is commonly used for X-ray data collection both to reduce crystal damage from radiation and to gather functional information by cryogenically trapping intermediates. However, the cooling process can damage the crystals. Limiting cooling-induced crystal damage often requires cryoprotection strategies, which can involve substantial screening of solution conditions and cooling protocols. Here, recent developments directed towards rational methods for cryoprotection are described. Crystal damage is described in the context of the temperature response of the crystal as a thermodynamic system. As such, the internal and external parts of the crystal typically have different cryoprotection requirements. A key physical parameter, the thermal contraction, of 26 different cryoprotective solutions was measured between 294 and 72,K. The range of contractions was 2,13%, with the more polar cryosolutions contracting less. The potential uses of these results in the development of cryocooling conditions, as well as recent developments in determining minimum cryosolution soaking times, are discussed. [source]

Serum Insulin-like Growth Factors, Insulin-like Growth Factor-binding Protein-3, and Risk of Lung Cancer Death: A Case-control Study Nested in the Japan Collaborative Cohort (JACC) Study

CANCER SCIENCE, Issue 12 2002
Kenji Wakai
To elucidate the roles of insulin-like growth factors (IGFs) in the development of lung cancer, we conducted a case-control study nested within the Japan Collaborative Cohort Study. Serum samples were collected at baseline from 39 140 men and women between 1988 and 1990. We measured serum IGF-I, IGF-II, and IGF-binding protein-3 (IGFBP-3) in 194 case subjects who subsequently died from lung cancer during an 8-year follow-up and in 9351 controls. The odds ratios (ORs), adjusted for smoking and other covariates, were smaller with higher levels of IGF-II and IGFBP-3. The ORs across quartiles were 0.41 (95% confidence interval [CI], 0.27,0.63), 0.47 (0.31,0.71), and 0.67 (0.46,0.98) for IGF-II (trend P=0.018), and 0.55 (95% CI, 0.37,0.81), 0.54 (0.36,0.82), and 0.67 (0.45,1.01) for IGFBP-3 (trend P=0.037). These peptides were not independently related to lung cancer risk when mutually adjusted. The risk was increased in the highest vs. the lowest quartile of IGF-I only after controlling for IGFBP-3 (OR, 1.74; 95% CI, 1.08,2.81). Limiting subjects to those followed for ,3 years strengthened the negative associations of IGF-II and IGFBP-3, whereas the ORs for IGF-I generally decreased. A higher level of circulating IGFBP-3 and/or IGF-II may decrease lung cancer risk. Elevated serum IGF-I may increase the risk, but this could partly be attributable to latent tumors. [source]

Ruthenium(II) Complexes for Two-Photon Absorption-Based Optical Power Limiting

CHEMPHYSCHEM, Issue 11 2008
Camille Girardot Dr.
Long-lived excitation: Novel bifluorene-substituted 1,10-phenanthroline-based RuII coordination complexes are presented (see picture). They fulfil several requirements for optimized optical power limiting in the visible-NIR, as they are stable, soluble and transparent at low laser fluences. The two-photon absorption of these complexes are strongly related to those of the ligand. [source]

Synthesis, Structure and Optical Limiting (OL) Properties of a Novel Incomplete Cubane-like Cluster [PPh4] [(,5 -C5Me5) WS3 -(CuBr) (Cul)2 (,-dppm)]

CHINESE JOURNAL OF CHEMISTRY, Issue 12 2003
Hong Yu
Abstract Reaction of [PPh4][,5 -C5Me5)WS3] with Cul, CuBr and bis-(diphenylphosphino)methane (dppm) (molar ratio = 1:2:1:1) in MeCN gave rise to [PPh4][(,5 -C5Me5)WS3 (CuBr)(Cul)2 -(,-dppm)] (1) in high yield. Compound 1 crystallizes in the monoclinic, space group P21/n with lattice parameters: a = 1.2906(4) nm, b = 1.5006(8) nm, c = 3.1484(6) nm, , = 92.12(2)°, V = 6.093(3) nm3, Z = 4. The structure of the anion of 1 contains an incomplete WS3Cu3 cubane-like core in which two Cul units are bridged by a dppm ligand. The W-Cu distances vary in the range of 0.2644(1),0.2793(1) nm. The optical limiting (OL) properties of 1 in MeCN were measured with the laser pulse-width of 12-ns at 532 nm, and the nanosecond OL effect may be due to the reverse saturable absorption (RSA) related to the excited triplet states. [source]

Application of the New Keystone-Species Concept to Prairie Dogs: How Well Does It Work?

CONSERVATION BIOLOGY, Issue 6 2000
Natasha B. Kotliar
This prompted Power et al. (1996) to refine the definition: keystone species have large effects on community structure or ecosystem function (i.e., high overall importance), and this effect should be large relative to abundance (i.e., high community importance). Using prairie dogs (Cynomys spp.) as an example, I review operational and conceptual difficulties encountered in applying this definition. As applied to prairie dogs, the implicit assumption that overall importance is a linear function of abundance is invalid. In addition, community importance is sensitive to abundance levels, the definition of community, and sampling scale. These problems arise largely from the equation for community importance, as used in conjunction with removal experiments at single abundance levels. I suggest that we shift from the current emphasis on the dualism between keystone and nonkeystone species and instead examine how overall and community importance vary (1) with abundance, (2) across spatial and temporal scales, and (3) under diverse ecological conditions. In addition, I propose that a third criterion be incorporated into the definition: keystone species perform roles not performed by other species or processes. Examination of how these factors vary among populations of keystone species should help identify the factors contributing to, or limiting, keystone-level functions, thereby increasing the usefulness of the keystone-species concept in ecology and conservation. Although the quantitative framework of Power et al. falls short of being fully operational, my conceptual guidelines may improve the usefulness of the keystone-species concept. Careful attention to the factors that limit keystone function will help avoid misplaced emphasis on keystone species at the expense of other species. Resumen: Se ha sugerido que el concepto de especie pilar no sea usado más en ecología y conservación, principalmente debido a que el concepto ha sido pobremente definido. Esto instigó a Power et al. (1996) a refinar la definición: las especies pilar tienen grandes efectos en la estructura de una comunidad o la función de un ecosistema (alta importancia en lo general), y este efecto debe ser grande en relación con la abundancia (alta importancia en la comunidad). Usando los perros de pradera (Cynomys spp) como ejemplo, revisé las dificultades operativas y conceptuales encontradas durante la aplicación de esta definición. Al aplicarse a perros de pradera, la suposición implícita de que la importancia en lo general es una función lineal de la abundancia es inválida. Además, la importancia en la comunidad es sensible a los niveles de abundancia, a la definición de comunidad y a la escala de muestreo. Estos problemas surgen, en gran medida, de la ecuación para la importancia en la comunidad, al ser usada conjuntamente con experimentos de remoción a un solo nivel de abundancia. Sugiero que el énfasis actual en la dualidad sobre especies pilares/no pilares cambie para examinar cómo varía la importancia en lo general y en la comunidad; (1) con la abundancia, (2) a lo largo de escalas espaciales y temporales, y (3) bajo diversas condiciones ecológicas. Además, propongo que sea incorporado un tercer criterio en la definición: las especies pilar llevan a cabo funciones no llevadas a cabo por otras especies o procesos. El análisis de cómo varían estos factores entre poblaciones de especies pilar ayudará a identificar los factores que contribuyen, o limitan las funciones a nivel pilar, incrementando con ello la utilidad del concepto de especie pilar en ecología y conservación. Aunque el marco de trabajo cuantitativo de Power et al. no llega a ser completamente operacional, mis guías conceptuales pueden mejorar la utilidad de este concepto. Una atención especial a los factores que limitan el funcionamiento pilar ayudaría a evitar un énfasis mal ubicado en especies pilar a costa de otras especies. [source]

Efficacy and safety of the dipeptidyl peptidase-4 inhibitor alogliptin in patients with type 2 diabetes inadequately controlled by glyburide monotherapy

DIABETES OBESITY & METABOLISM, Issue 2 2009
R. E. Pratley
Aim:, To evaluate the efficacy and safety of alogliptin, a potent and highly selective dipeptidyl peptidase-4 (DPP-4) inhibitor, in combination with glyburide in patients with type 2 diabetes inadequately controlled by sulphonylurea monotherapy. Methods:, After a 2-week screening period, adult patients 18,80 years of age entered a 4-week run-in/stabilization period in which they were switched from their own sulphonylurea medication to an equivalent dose of glyburide (open label) plus placebo (single blind). After the run-in period, patients were randomly assigned to double-blind treatment with alogliptin 12.5 mg (n = 203), alogliptin 25 mg (n = 198), or placebo (n = 99) for 26 weeks. The primary end-point was change from baseline to week 26 in glycosylated haemoglobin (HbA1c). Secondary end-points included clinical response rates and changes in fasting plasma glucose, ,-cell function (fasting proinsulin, insulin, proinsulin/insulin ratio, and C-peptide, and homeostasis model assessment ,-cell function), body weight, and safety end-points [adverse events (AEs), clinical laboratory tests, vital signs and electrocardiographic readings]. Results:, The study population had a mean age of 57 years and a mean disease duration of 8 years; it was well balanced for gender (52% women) and was mainly white (71%). The mean baseline HbA1c was approximately 8.1% in each group. Significantly greater least squares (LS) mean reductions in HbA1c were seen at week 26 with alogliptin 12.5 mg (,0.38%) and 25 mg (,0.52%) vs. placebo (+0.01%; p < 0.001), and more patients in the alogliptin 25-mg group had HbA1c levels ,7.0% at week 26 (34.8%, p = 0.002) vs. placebo (18.2%). Proportionately more patients in the alogliptin 12.5 mg (47.3%) and 25 mg (50.5%) groups had an HbA1c reduction ,0.5% from baseline compared with patients in the placebo group (26.3%; p < 0.001). Minor improvements in individual markers of ,-cell function were seen with alogliptin, but no significant treatment group differences were noted relative to placebo. Minor LS mean changes in body weight were noted across groups (placebo, ,0.20 kg; alogliptin 12.5 mg, +0.60 kg; alogliptin 25 mg, +0.68 kg). AEs were reported for 63,64% of patients receiving alogliptin and 54% of patients receiving placebo. Few AEs were treatment limiting (2.0,2.5% across groups), and serious AEs (2.0,5.6%) were infrequent, similar across groups, and generally considered not related to treatment. The incidences of hypoglycaemia for placebo, alogliptin 12.5 mg and alogliptin 25 mg groups were 11.1, 15.8 and 9.6% respectively. Conclusions:, In patients with type 2 diabetes inadequately controlled by glyburide monotherapy, the addition of alogliptin resulted in clinically significant reductions in HbA1c without increased incidence of hypoglycaemia. [source]

Determination of cationic mobilities and pKa values of 22 amino acids by capillary zone electrophoresis

ELECTROPHORESIS, Issue 2 2004
eláková, ina V
Abstract The effective mobilities of the cationic forms of common amino acids , mostly proteinogenic , were determined by capillary zone electrophoresis in acidic background electrolytes at pH between 2.0 and 3.2. The underivatized amino acids were detected by the double contactless conductivity detector. Experimentally measured effective mobilities were fitted with the suitable regression functions in dependence on pH of the background electrolyte. The parameters of the given regression function corresponded to the values of the actual mobilities and the mixed dissociation constants (combining activities and concentrations) of the compound related to the actual ionic strength. McInnes approximation and Onsager theory were used to obtain thermodynamic dissociation constants (pKa) and limiting (absolute) ionic mobilities. [source]

Physiological responses of Matricaria chamomilla to cadmium and copper excess

ENVIRONMENTAL TOXICOLOGY, Issue 1 2008
Jozef Ková
Abstract Physiological responses of Matricaria chamomilla plants exposed to cadmium (Cd) and copper (Cu) excess (3, 60, and 120 ,M for 7 days) with special emphasis on phenolic metabolism were studied. Cu at 120 ,M reduced chamomile growth, especially in the roots where it was more abundant than Cd. Notwithstanding the low leaf Cu amount (37.5 ,g g,1 DW) in comparison with Cd (237.8 ,g g,1 DW) at 120 ,M, it caused reduction of biomass accumulation, Fv/Fm ratio and soluble proteins. In combination with high accumulation of phenolics, strong reduction of proteins and high GPX activity in the roots, this supports severe redox Cu properties. In terms of leaf phenylalanine ammonia-lyase (PAL) activity, it seems that Cd had a stimulatory effect during the course of the experiment, whereas Cu was found to stimulate it after 7-day exposure. The opposite trend was visible in the roots, where Cd had a stimulatory effect at high doses but Cu mainly at the highest dose. This supports the assumption of different PAL time dynamics under Cd and Cu excess. A dose of 60 and 120 ,M Cu led to 2- and 3-times higher root lignin accumulation while the same Cd doses increased it by 33 and 68%, respectively. A Cu dose of 120 ,M can be considered as limiting for chamomile growth under conditions of present research, while resistance to high Cd doses was confirmed. However, PAL and phenolics seemed to play an important role in detoxification of Cd- and Cu-induced oxidative stress. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2008. [source]

Kindling Limits the Interictal Neuronal Temporal Response Properties in Cat Primary Auditory Cortex

EPILEPSIA, Issue 2 2005
Pamela A. Valentine
Summary:,Purpose: The present study examined the effect of electrical kindling on the interictal temporal response properties of single units recorded from primary auditory cortex (AI) of the adult cat. Methods: Cats were permanently implanted with electrodes in AI, kindled twice daily for 40 sessions, and the contralateral AI was subsequently mapped. Kindling stimulation consisted of 1-s trains of biphasic square-wave pulses applied at a frequency of 60 Hz, 100 ,A above the afterdischarge (AD) threshold. The EEG activity was recorded during each kindling session, and the behavioral manifestation was scored. Subsequent to kindling, multiple single-unit responses were recorded under ketamine anesthesia in response to 1-s-long periodic click trains, with click rates between 2 and 64 Hz. Neuronal responses were characterized according to their ability to respond in time-locked fashion to the clicks. Results: Kindling stimulation resulted in progression of the AD characteristics and seizure behavior, with six of 10 kindled cats reaching a fully generalized state. In the fully kindled cats, the best modulation frequencies and limiting following rates for the single-unit responses were significantly lower compared with those of naive and sham controls. Conclusions: Repeated epileptiform activity interferes with temporal processing in cat auditory cortex in the interictal state. This may have implications for people with epileptic foci in auditory-related areas. [source]

Bacterivorous grazers facilitate organic matter decomposition: a stoichiometric modeling approach

FEMS MICROBIOLOGY ECOLOGY, Issue 2 2009
Hao Wang
Abstract There is widespread empirical evidence that protist grazing on bacteria reduces bacterial abundances but increases bacteria-mediated decomposition of organic matter. This paradox has been noted repeatedly in the microbiology literature but lacks a generally accepted mechanistic explanation. To explain this paradox quantitatively, we develop a bacteria-grazer model of organic matter decomposition that incorporates protozoa-driven nutrient recycling and stoichiometry. Unlike previous efforts, the current model includes explicit limitation, via Liebig's law of minimum, by two possible factors, nutrient and carbon densities, as well as their relative ratios in bacteria and grazers. Our model shows two principal results: (1) when the environment is carbon limiting, organic matter can always be decomposed completely, regardless of the presence/absence of grazers; (2) when the environment is nutrient (such as nitrogen) limiting, it is possible for organic matter to be completely decomposed in the presence, but not absence, of grazers. Grazers facilitate decomposition by releasing nutrients back into the environment, which would otherwise be limiting, while preying upon bacteria. Model analysis reveals that facilitation of organic matter decomposition by grazers is positively related to the stoichiometric difference between bacteria and grazers. In addition, we predict the existence of an optimal density range of introduced grazers, which maximally facilitate the decomposition of organic matter in a fixed time period. This optimal range reflects a trade-off between grazer-induced nutrient recycling and grazer-induced mortality of bacteria. [source]

Restoration options for potential persistence of submersed aquatic vegetation: combining ecological, hydrodynamic and sediment transport modelling

FRESHWATER BIOLOGY, Issue 4 2008
ELLY P. H. BEST
Summary 1. Restoration of shallow turbid lakes to promote growth of submersed aquatic vegetation (SAV) requires knowledge of the environmental factors affecting SAV growth and persistence, and a means to predict the success of SAV reestablishment under different management scenarios to improve these environmental conditions. We used a dynamic ecological modelling approach relating SAV responses to changes in physical and chemical conditions, with information on water level, flow and transparency being provided by hydrodynamic and sediment transport models. 2. The potential persistence of Vallisneria americana was similar under simulated environmental conditions in 1946 and in 1954, as was the potential persistence of Potamogeton pectinatus, indicating that the disappearance of V. americana from Peoria Lake (U.S.A.) previously attributed to an extended spring flood in 1954, may have been related to the combined effects of changes in water level, flow and water transparency as well as possibly other factors. 3. Recent environmental conditions (for 2000) proved not to be conducive for the colonization and persistence potential of V. americana, but would allow colonization by P. pectinatus. The construction of a hypothetical levee along the eastern descending line of the navigation channel in Upper Peoria Lake, which was expected to reduce fetch- and navigation-related turbidity, did not improve the situation for V. americana and overall deteriorated the situation for P. pectinatus. Thus, such a hydraulic alteration, generally considered as beneficial for SAV restoration, may not always be successful. 4. The results of the simulations indicated that the environmental conditions for potential persistence in Peoria Lake were generally less favourable for V. americana than for P. pectinatus. Measures suggested to restore SAV communities in such a lake should aim at reducing concentrations of total suspended solids at the point of inflow by a factor of three to four and limiting fetch- and navigation-related resuspension. [source]

Growth rates of phytoplankton under fluctuating light

FRESHWATER BIOLOGY, Issue 2 2000
Elena Litchman
Summary 1The effect of light fluctuations on the growth rates of four species of freshwater phytoplankton was investigated. Experimental light regimes included constant irradiance and fluctuations of a step function form, with equal proportion of high (maximum of 240 µmol photons m -2 s -1) and low light (minimum of 5 µmol photons m -2 s -1) (or dark) in a period. Fluctuations of 1, 8 and 24-h periods were imposed over several average irradiances (25, 50, 100 and 120 µmol photons m -2 s -1). 2Growth rate responses to fluctuations were species-specific and depended on both the average irradiance and the period of fluctuations. Fluctuations at low average irradiances slightly increased growth rate of the diatom Nitzschia sp. and depressed growth of the cyanobacterium Phormidium luridum and the green alga Sphaerocystis schroeteri compared to a constant irradiance. 3Fluctuations at higher average irradiance did not have a significant effect on the growth rates of Nitzschia sp. and Sphaerocystis schroeteri (fluctuations around saturating irradiances) and slightly increased the growth rates of the cyanobacteria Anabaena flos-aquae and Phormidium luridum (when irradiance fluctuated between limiting and inhibiting levels). 4In general, the effect of fluctuations tended to be greater when irradiance fluctuated between limiting and saturating or inhibiting levels of a species growth-irradiance curve compared to fluctuations within a single region of the curve. 5The growth rates of species under fluctuating light could not always be predicted from their growth-irradiance curves obtained under constant irradiance. When fluctuations occur between limiting and saturating or inhibiting irradiances for the alga and when the period of fluctuations is long (greater than 8 h), steady-state growth-irradiance curves may be insufficient to predict growth rates adequately. Consequently, additional data on physiological acclimation, such as changes in photosynthetic parameters, may be required for predictions under non-constant light supply in comparison to constant conditions. [source]

Does pregnancy affect swimming performance of female Mosquitofish, Gambusia affinis?

FUNCTIONAL ECOLOGY, Issue 3 2002
I. Plaut
Summary 1.,The cost of reproduction due to limiting of the reproductive female's locomotion capability has been suggested many times, but has rarely been directly examined, especially in fishes. Here, the effect of pregnancy on swimming performance in the viviparous Mosquitofish, Gambusia affinis, was studied. 2.,Eight females of G. affinis were isolated, each in a separate aquarium, and critical swimming speed (Ucrit), body mass (BM) and cross-section area were measured every 5 days from the beginning of the pregnancy until 2,4 days after parturition. 3.,Swimming kinematics (tail beat frequency and amplitude) was measured in non-pregnant and pregnant females at different swimming speeds. 4.,BM increased during pregnancy from 0·47 ± 0·13 g to 0·72 ± 0·19 g, and the cross-section area also increased during pregnancy from 0·21 ± 0·06 cm2 to 0·32 ± 0·07 cm2. Ucrit decreased from 25·0 ± 1·3 cm s,1 before pregnancy to 20·1 ± 1·5 cm s,1 just before parturition, and returned to 24·7 ± 1·4 cm s,1 2,4 days after parturition. Interindividual variation was repeatable and reflects real differences among individuals. 5.,Swimming kinematics was not affected by pregnancy. 6.,The results suggest that reductions in Ucrit are probably because of aerobic constraints and not necessarily due to hydrodynamic changes resulting from changing in body form or plasticity. Moreover, the reduction in Ucrit is, potentially, a ,cost of reproduction' owing to decrease in the ability to gain food during pregnancy in G. affinis females. [source]

Optical Power Limiters: Symmetric Versus Unsymmetric Platinum(II) Bis(aryleneethynylene)s with Distinct Electronic Structures for Optical Power Limiting/Optical Transparency Trade-off Optimization (Adv. Mater.

ADVANCED FUNCTIONAL MATERIALS, Issue 4 2009
8/2009)
The development of symmetric and unsymmetric platinum(II) bis(acetylide)s as highly transparent optical limiters is described by Wong and co-workers on page 531. Their excited state character is governed by electronic structure, which significantly affects their photophysical properties and optical power limiting (OPL) behavior. The sound OPL responses and low OPL thresholds together with their excellent optical transparency render these materials very promising candidates for practical devices for the protection of human eyes and other delicate electro-optic sensors. [source]

Symmetric Versus Unsymmetric Platinum(II) Bis(aryleneethynylene)s with Distinct Electronic Structures for Optical Power Limiting/Optical Transparency Trade-off Optimization

ADVANCED FUNCTIONAL MATERIALS, Issue 4 2009
Guijiang Zhou
Abstract A new series of symmetric and unsymmetric Pt(II) bis(acetylide) complexes of the type DC,CPt(PBu3)2C,CD (DPtD), AC,CPt(PBu3)2C,CA (APtA) and DC,CPt(PBu3)2C,CA (DPtA) (D, donor groups; A, acceptor groups) are synthesized, and show superior optical power limiting (OPL)/optical transparency trade-offs. By tailoring the electronic properties of the aryleneethynylene group, distinct electronic structures for these metalated complexes can be obtained, which significantly affect their photophysical behavior and OPL properties for a nanosecond laser pulse at 532,nm. Electronic influence of the ligand type and the molecular symmetry of metal group on the optical transparency/nonlinearity optimization is thoroughly elucidated. Generally, aryleneethynylene ligands with , electron-accepting nature will effectively enhance the harvesting efficiency of the triplet excited states. The ligand variation to the OPL strength of these Pt(II) compounds follows the order: DPtD,>,DPtA,>,APtA. These results could be attributed to the distinctive excited state character induced by their different electronic structures, on the basis of the data from both photophysical studies and theoretical calculations. All of the complexes show very good optical transparencies in the visible-light region and exhibit excellent OPL responses with very impressive figure of merit ,ex/,o values (up to 17), which remarkably outweigh those of state-of-the-art reverse saturable absorption dyes such as C60 and metallophthalocyanines with very poor transparencies. Their lower optical-limiting thresholds (0.05,J,cm,2 at 92% linear transmittance) compared with that of the best materials (ca. 0.07,J,cm,2 for InPc and PbPc dyes) currently in use will render these highly transparent materials promising candidates for practical OPL devices for the protection of human eyes and other delicate electro-optic sensors. [source]

Accumulation of carbon and nitrogen by old arable land reverting to woodland

GLOBAL CHANGE BIOLOGY, Issue 6 2003
P. R. POULTON
Abstract The accumulation of carbon (C) and nitrogen (N) was measured on two sites on Rothamsted Farm that had been fenced off some 120 years ago and allowed to revert naturally to woodland. The sites had previously been arable for centuries. One had been chalked and was still calcareous; the other had never been chalked and the pH fell from 7.1 in 1883 to 4.4 in 1999. The acidic site (Geescroft wilderness) is now a deciduous wood, dominated by oak (Quercus robor); the calcareous site (Broadbalk wilderness) is now dominated by ash (Fraxinus excelsior), with sycamore (Acer pseudoplatanus) and hawthorn (Craetagus monogyna) as major contributors. The acidic site gained 2.00 t C ha,1 yr,1 over the 118-year period (0.38 t in litter and soil to a depth of 69 cm, plus an estimated 1.62 t in trees and their roots); the corresponding gains of N were 22.2 kg N ha,1 year,1 (15.2 kg in the soil, plus 6.9 kg in trees and their roots). The calcareous site gained 3.39 t C ha,1 year,1 over the 120-year period (0.54 t in the soil, plus an estimated 2.85 t in trees and roots); for N the gains were 49.6 kg ha,1 yr,1 (36.8 kg in the soil, plus 12.8 kg in trees and roots). Trees have not been allowed to grow on an adjacent part of the calcareous site. There is now a little more C and N in the soil from this part than in the corresponding soil under woodland. We argue from our results that N was the primary factor limiting plant growth and hence accumulation of C during the early stages of regeneration in these woodlands. As soil organic N accumulates and the sites move towards N saturation, other factors become limiting. Per unit area of woodland, narrow strips; that is, wide hedges with trees, are the most efficient way of sequestering C , provided that they are not short of N. [source]

Optical Power Limiters Based on Colorless Di-, Oligo-, and Polymetallaynes: Highly Transparent Materials for Eye Protection Devices,

ADVANCED FUNCTIONAL MATERIALS, Issue 6 2007
G.-J. Zhou
Abstract The synthesis, characterization, and photophysics of a series of solution-processable and tractable di-, oligo-, and polymetallaynes of some group 10,12 transition metals are presented. Most of these materials are colorless with very good optical transparencies in the visible spectral region and exhibit excellent optical power limiting (OPL) for nanosecond laser pulse. Their OPL responses outweigh those of the state-of-the-art reverse saturable absorption dyes such as C60, metalloporphyrins, and metallophthalocyanines that are all associated with very poor optical transparencies. On the basis of the results from photophysical studies and theoretical calculations, both the absorption of triplet and intramolecular charge-transfer states can contribute to the enhancement of the OPL properties for these materials. Electronic influence of the type, spatial arrangement, and geometry of metal groups on the optical transparency/nonlinearity optimization is evaluated and discussed in detail. The positive contribution of transition metal ions to the OPL of these compounds generally follows the order: Pt,>,Au,>,Hg,>,Pd. The optical-limiting thresholds for these polymetallaynes can be as low as 0.07,J,cm,2 at 92,% linear transmittance and these highly transparent materials manifest very impressive figure of merit ,ex/,o values (up to 22.48), which are remarkably higher than those of the benchmark C60 and metal phthalocyanine complexes. The present work demonstrates an attractive approach to developing materials offering superior OPL/optical transparency trade-offs and these metallopolyynes are thus very promising candidates for use in practical OPL devices for the protection of human eyes and other delicate optical sensors. [source]

The use of muscle protein for egg production in the Zebra Finch Taeniopygia guttata

IBIS, Issue 2 2002
Mat Cottam
Pectoral muscle can be an important source of protein for birds. During egg formation Zebra Finches Taeniopygia guttata are able to compensate for nutritional inadequacies in their diet by utilization of the protein in their flight muscles. This analysis of flight muscle sarcoplasm supported earlier observations of protein depletion during egg production. However, SDS gel electrophoresis of the sarcoplasm produced no evidence to support a previous suggestion of the existence of a high molecular weight storage protein, and it is thought that the original observation may have arisen as an artefact of experimental methodology. During laying, protein removal from the sarcoplasm occurred over a range of different proteins and was not confined to any one specific protein band. Additionally, the protein band most reduced over the course of laying did not contain elevated levels of the amino acids most limiting to egg production. These results indicate that during laying, flight muscle sarcoplasm contributes towards the nutrient requirements of egg production from general protein reserves, rather than from a specific storage protein containing elevated levels of limiting amino acids. [source]

Broadband Nonlinear Optical Response of Graphene Dispersions

ADVANCED MATERIALS, Issue 23 2009
Jun Wang
A series of unoxidized and defect-free graphene dispersions with large populations of single and multilayer graphenes is prepared by employing high-yield exfoliation of graphene in the liquid phase. The graphene dispersions exhibit broadband optical limiting at 532 and 1064,nm. Nonlinear scattering, originated from the thermally induced solvent bubbles and microplasmas, is responsible for this nonlinear behavior. [source]

Health-related quality of life of youth with inflammatory bowel disease: A comparison with published data using the PedsQL 4.0 generic core scales

INFLAMMATORY BOWEL DISEASES, Issue 6 2010
Jennifer Hauser Kunz PhD
Abstract Background: This study compared youth and parent-proxy reports of health-related quality of life (HRQoL) among youth with inflammatory bowel disease (IBD) to published comparison group data and examined concordance between youth and parent-proxy reports of HRQoL. Methods: One hundred thirty-six youth and parent-proxy reports on the PedsQL 4.0 Generic Core Scales were compared to published data from chronically ill, acutely ill, and healthy comparison groups using independent samples t -tests. Reporter agreement was examined using paired samples t -tests and intraclass correlations (ICCs). Results: Youth with IBD reported lower psychosocial functioning than the healthy comparison group, higher physical and social functioning than the chronically ill group, and lower school functioning than all published comparison groups. Parent-proxy reports of youth HRQoL were higher than the chronically ill group, but lower than the healthy group on all scales except psychosocial functioning. Youth with active IBD reported lower physical health domain scores than youth with inactive disease. Concordance between youth and parent-proxy reports was moderate, with the lowest agreement in school and social functioning. Conclusions: Youth with IBD and their parents rate HRQoL as lower than healthy youth but do not perceive the impact of IBD to be as limiting as in other chronic conditions. Youth report suggests that IBD may be particularly detrimental to HRQoL in the school functioning domain. Moderate agreement between parent and youth reports substantiates continued use of multiple informants in studies of pediatric HRQoL. Inflamm Bowel Dis 2010 [source]

Nucleophilic heteroaromatic substitution: Kinetics of the reactions of nitropyridines with aliphatic amines in dipolar aprotic solvents

INTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 3 2008
Chukwuemeka Isanbor
Rate data are reported for the reactions of 2-chloro-5-nitropyridine 2a, 2-chloro-3-nitropyridine 2b, and the corresponding 2-phenoxy derivatives 2c with n -butylamine, pyrrolidine and piperidine and 2d with n -butylamine and pyrrolidine in dimethyl sulfoxide (DMSO) as solvent. The same reactions in acetonitrile had been reported earlier (Crampton et al., Eur J Org Chem 2007, 1378,1383). Values in these solvents are compared with those of 2,4-dinitrochlorobenzene 3a, 2,6-dinitrochlorobenzene 3b, and the corresponding nitroactivated diphenyl ethers 3c and 3d. Reactions with n -butylamine in both solvents gave values of kobs, which increase linearly with amine concentration indicating that nucleophilic attack is rate limiting. The only exception is the reactions in acetonitrile with 2c where base catalysis was observed. Values of k1, the rate constant for the nucleophilic attack, decrease in the order pyrrolidine > piperidine > n -butylamine. In acetonitrile, kinetic data show that k/k ratios are more than unity while the inverse is the case in DMSO. With the phenoxy derivatives, substitution was the only process observed. Base catalysis detected in the reactions of the 1-phenoxy derivatives is attributed to rate-limiting deprotonation of the initially formed zwitterionic intermediate. Our results shed more light on fundamental aspects of activation, hydrogen bonding, and steric effects associated with an aza or a nitro group in the molecules investigated as it affects the nucleophilic aromatic substitution (SNAr) reaction pathways. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 125,135, 2008 [source]

Influence of seasonal pressure patterns on temporal variability of vegetation activity in Central Siberia

INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 3 2006
Sergio M. Vicente-Serrano
Abstract This paper analyses the spatial distribution of the inter-annual variability of vegetation activity in central Siberia and its relationship with atmospheric circulation variability. We used NOAA-AVHRR NDVI series from Pathfinder Land Data Set at 1° of spatial resolution, and we calculated the annual vegetation activity in each pixel (aNDVI) from 1982 to 2001. Principal component analysis (PCA) was used to determine the general spatial patterns of inter-annual variability of vegetation activity. We identified three main modes, which explain more than 50% of the total variance, each corresponding to a large region. By means of surface pressure grids, we analysed the main patterns of the seasonal atmospheric circulation in the study area: its variability was summarised by means of a few circulation modes and the patterns differ significantly between winter, spring and summer. However, a pattern with a North,South dipole structure represents the general spatial pattern of atmospheric circulation. We investigated the effect of seasonal atmospheric circulation patterns on the inter-annual variation of vegetation activity. In general, the strongest relationships between the atmospheric circulation variability, climate and the aNDVI variability were found in areas where the climatic characteristics are more limiting for the vegetation development, such as the northern regions. This may be explained by the fact that in these areas the variability of atmospheric circulation modes determines summer temperatures, which have a direct impact on vegetation activity. Copyright © 2006 Royal Meteorological Society. [source]

Strong Optical Limiting of Soluble Axially Substituted Gallium and Indium Phthalocyanines,

Efficacy and safety of dutasteride in Japanese men with benign prostatic hyperplasia

INTERNATIONAL JOURNAL OF UROLOGY, Issue 9 2009
Taiji Tsukamoto
Objectives: To assess the efficacy and safety of dutasteride in Japanese men with benign prostatic hyperplasia (BPH). Methods: This was a randomized, double-blind, placebo-controlled, parallel-group study. A total of 378 subjects with clinical BPH having an International Prostate Symptom Score (IPSS) of 8 points or greater, a prostate volume of 30 mL or greater, and a maximal urinary flow rate (Qmax) of 15 mL/s or less were randomized to receive placebo or dutasteride once daily for 52 weeks. Subjects were stratified according to tamsulosin use at baseline. The numbers of subjects with and without tamsulosin use were 242 and 136, respectively. IPSS, Qmax, prostate volume and drug safety were evaluated. Results: Continued improvement in IPSS was noted in the dutasteride group, and dutasteride significantly decreased IPSS compared with placebo. At week 52, dutasteride significantly improved Qmax and prostate volume compared with placebo. Drug-related sexual function events in the dutasteride group were infrequent and generally were not treatment limiting. Conclusions: Dutasteride improves urinary symptoms and flow rate and reduces prostate volume. In Japanese men with BPH, it is effective and generally well tolerated during the one-year treatment period. [source]

Severe eosinophilic cystitis in a woman with anorexia nervosa

INTERNATIONAL JOURNAL OF UROLOGY, Issue 8 2006
JOE PHILIP
Abstract, Eosinophilic cystitis is a rare inflammatory disorder. It is considered to be self limiting necessitating only supportive therapy. Surgical intervention is unusual. We report here an association between eosinophilic cystitis and anorexia nervosa in an adult woman requiring radical surgery for progressive relentless disease. Estrogen deficiency associated with a possible allergic etiology could explain this association. [source]

The effect of pea cultivar and water stress on root and shoot competition between vegetative plants of maize and pea

JOURNAL OF APPLIED ECOLOGY, Issue 1 2001
Tzehaye Semere
Summary 1Improvements in intercrop yields may be achieved through an understanding of yield advantages due to above-ground or below-ground interactions. 2Forage maize and two morphologically contrasting cultivars of pea (leafy cv. Bohatyr and semi-leafless cv. Grafila) were grown alone and in additive mixtures, under two contrasting levels of soil moisture (± water stress). 3The mechanism of competition between maize and pea was studied by separating the effects of root competition and shoot competition, using soil and aerial partitions. Plants were grown in rectangular tanks in a glasshouse. 4Leafy pea cv. Bohatyr was as competitive as maize, both below-ground and above-ground, whereas semi-leafless pea cv. Grafila was less competitive than maize or pea cv. Bohatyr. The greater competitive ability of the leafy pea, both above- and below-ground, was probably due to its greater growth rate, associated with its greater leaf area. 5The competitive ability of maize, relative to peas, was considerably reduced by water stress. Both the root and shoot competitive abilities of pea were greater under water stress, compared with those of maize. 6Relative yield total (RYT) values were significantly greater when maize and pea were subjected to shoot competition only (RYT = 1·76) than when subjected to root competition (RYT = 1·17) or when subjected to both shoot and root competition (RYT = 1·13). This reflects the fact that the effects of root competition were greater than those of shoot competition. 7Root competition decreased the shoot dry weights, plant height and leaf area of both maize and pea, whereas shoot competition had no significant effect on these attributes, indicating that soil resources, i.e. mineral nutrients and water, were more limiting than light. [source]