WorldWideScience

Sample records for biodegradation response variability

  1. Immunological Response to Biodegradable Magnesium Implants

    Science.gov (United States)

    Pichler, Karin; Fischerauer, Stefan; Ferlic, Peter; Martinelli, Elisabeth; Brezinsek, Hans-Peter; Uggowitzer, Peter J.; Löffler, Jörg F.; Weinberg, Annelie-Martina

    2014-04-01

    The use of biodegradable magnesium implants in pediatric trauma surgery would render surgical interventions for implant removal after tissue healing unnecessary, thereby preventing stress to the children and reducing therapy costs. In this study, we report on the immunological response to biodegradable magnesium implants—as an important aspect in evaluating biocompatibility—tested in a growing rat model. The focus of this study was to investigate the response of the innate immune system to either fast or slow degrading magnesium pins, which were implanted into the femoral bones of 5-week-old rats. The main alloying element of the fast-degrading alloy (ZX50) was Zn, while it was Y in the slow-degrading implant (WZ21). Our results demonstrate that degrading magnesium implants beneficially influence the immune system, especially in the first postoperative weeks but also during tissue healing and early bone remodeling. However, rodents with WZ21 pins showed a slightly decreased phagocytic ability during bone remodeling when the degradation rate reached its maximum. This may be due to the high release rate of the rare earth-element yttrium, which is potentially toxic. From our results we conclude that magnesium implants have a beneficial effect on the innate immune system but that there are some concerns regarding the use of yttrium-alloyed magnesium implants, especially in pediatric patients.

  2. Biodegradation of free cyanide and subsequent utilisation of biodegradation by-products by Bacillus consortia: optimisation using response surface methodology.

    Science.gov (United States)

    Mekuto, Lukhanyo; Ntwampe, Seteno Karabo Obed; Jackson, Vanessa Angela

    2015-07-01

    A mesophilic alkali-tolerant bacterial consortium belonging to the Bacillus genus was evaluated for its ability to biodegrade high free cyanide (CN(-)) concentration (up to 500 mg CN(-)/L), subsequent to the oxidation of the formed ammonium and nitrates in a continuous bioreactor system solely supplemented with whey waste. Furthermore, an optimisation study for successful cyanide biodegradation by this consortium was evaluated in batch bioreactors (BBs) using response surface methodology (RSM). The input variables, that is, pH, temperature and whey-waste concentration, were optimised using a numerical optimisation technique where the optimum conditions were found to be as follows: pH 9.88, temperature 33.60 °C and whey-waste concentration of 14.27 g/L, under which 206.53 mg CN(-)/L in 96 h can be biodegraded by the microbial species from an initial cyanide concentration of 500 mg CN(-)/L. Furthermore, using the optimised data, cyanide biodegradation in a continuous mode was evaluated in a dual-stage packed-bed bioreactor (PBB) connected in series to a pneumatic bioreactor system (PBS) used for simultaneous nitrification, including aerobic denitrification. The whey-supported Bacillus sp. culture was not inhibited by the free cyanide concentration of up to 500 mg CN(-)/L, with an overall degradation efficiency of ≥ 99 % with subsequent nitrification and aerobic denitrification of the formed ammonium and nitrates over a period of 80 days. This is the first study to report free cyanide biodegradation at concentrations of up to 500 mg CN(-)/L in a continuous system using whey waste as a microbial feedstock. The results showed that the process has the potential for the bioremediation of cyanide-containing wastewaters.

  3. Endothelial Cellular Responses to Biodegradable Metal Zinc.

    Science.gov (United States)

    Ma, Jun; Zhao, Nan; Zhu, Donghui

    Biodegradable zinc (Zn) metals, a new generation of biomaterials, have attracted much attention due to their excellent biodegradability, bioabsorbability, and adaptability to tissue regeneration. Compared with magnesium (Mg) and iron (Fe), Zn exhibits better corrosion and mechanical behaviors in orthopedic and stent applications. After implantation, Zn containing material will slowly degrade, and Zn ions (Zn(2+)) will be released to the surrounding tissue. For stent applications, the local Zn(2+)concentration near endothelial tissue/cells could be high. However, it is unclear how endothelia will respond to such high concentrations of Zn(2+), which is pivotal to vascular remodeling and regeneration. Here, we evaluated the short-term cellular behaviors of primary human coronary artery endothelial cells (HCECs) exposed to a concentration gradient (0-140 μM) of extracellular Zn(2+). Zn(2+) had an interesting biphasic effect on cell viability, proliferation, spreading, and migration. Generally, low concentrations of Zn(2+) promoted viability, proliferation, adhesion, and migration, while high concentrations of Zn(2+) had opposite effects. For gene expression profiles, the most affected functional genes were related to cell adhesion, cell injury, cell growth, angiogenesis, inflammation, vessel tone, and coagulation. These results provide helpful information and guidance for Zn-based alloy design as well as the controlled release of Zn(2+)in stent and other related medical applications.

  4. Variability of soil potential for biodegradation of petroleum hydrocarbons in a heterogeneous subsurface

    DEFF Research Database (Denmark)

    Kristensen, Andreas Houlberg; Poulsen, Tjalfe; Mortensen, Lars;

    2010-01-01

    Quantifying the spatial variability of factors affecting natural attenuation of hydrocarbons in the unsaturated zone is important to (i) performing a reliable risk assessment and (ii) evaluating the possibility for bioremediation of petroleum-polluted sites. Most studies to date have focused......, resulting in an accumulation of pollution within coarse sandy lenses. Air-filled porosity, readily available phosphorous, and the first-order rate constant (k1) of benzene obtained from slurry biodegradation experiments were found to depend on geologic sample characterization (P ... for biodegradation was highly variable, which from autoregressive state-space modeling was partly explained by changes in soil air-filled porosity and gravimetric water content. The results suggest considering biological heterogeneity when evaluating the fate of contaminants in the subsurface....

  5. Response surface analysis to improve dispersed crude oil biodegradation

    Energy Technology Data Exchange (ETDEWEB)

    Zahed, Mohammad A.; Aziz, Hamidi A.; Mohajeri, Leila [School of Civil Engineering, Universiti Sains Malaysia, Nibong Tebal, Penang (Malaysia); Isa, Mohamed H. [Civil Engineering Department, Universiti Teknologi PETRONAS, Tronoh, Perak (Malaysia)

    2012-03-15

    In this research, the bioremediation of dispersed crude oil, based on the amount of nitrogen and phosphorus supplementation in the closed system, was optimized by the application of response surface methodology and central composite design. Correlation analysis of the mathematical-regression model demonstrated that a quadratic polynomial model could be used to optimize the hydrocarbon bioremediation (R{sup 2} = 0.9256). Statistical significance was checked by analysis of variance and residual analysis. Natural attenuation was removed by 22.1% of crude oil in 28 days. The highest removal on un-optimized condition of 68.1% were observed by using nitrogen of 20.00 mg/L and phosphorus of 2.00 mg/L in 28 days while optimization process exhibited a crude oil removal of 69.5% via nitrogen of 16.05 mg/L and phosphorus 1.34 mg/L in 27 days therefore optimization can improve biodegradation in shorter time with less nutrient consumption. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Variability of soil potential for biodegradation of petroleum hydrocarbons in a heterogeneous subsurface.

    Science.gov (United States)

    Kristensen, Andreas H; Poulsen, Tjalfe G; Mortensen, Lars; Moldrup, Per

    2010-07-15

    Quantifying the spatial variability of factors affecting natural attenuation of hydrocarbons in the unsaturated zone is important to (i) performing a reliable risk assessment and (ii) evaluating the possibility for bioremediation of petroleum-polluted sites. Most studies to date have focused on the shallow unsaturated zone. Based on a data set comprising analysis of about 100 soil samples taken in a 16 m-deep unsaturated zone polluted with volatile petroleum compounds, we statistically and geostatistically analysed values of essential soil properties. The subsurface of the site was highly layered, resulting in an accumulation of pollution within coarse sandy lenses. Air-filled porosity, readily available phosphorous, and the first-order rate constant (k(1)) of benzene obtained from slurry biodegradation experiments were found to depend on geologic sample characterization (P<0.05), while inorganic nitrogen was homogenously distributed across the soil stratigraphy. Semivariogram analysis showed a spatial continuity of 4-8.6 m in the vertical direction, while it was 2-5 times greater in the horizontal direction. Values of k(1) displayed strong spatial autocorrelation. Even so, the soil potential for biodegradation was highly variable, which from autoregressive state-space modeling was partly explained by changes in soil air-filled porosity and gravimetric water content. The results suggest considering biological heterogeneity when evaluating the fate of contaminants in the subsurface.

  7. Variability in physical contamination assessment of source segregated biodegradable municipal waste derived composts.

    Science.gov (United States)

    Echavarri-Bravo, Virginia; Thygesen, Helene H; Aspray, Thomas J

    2017-01-01

    Physical contaminants (glass, metal, plastic and 'other') and stones were isolated and categorised from three finished commercial composts derived from source segregated biodegradable municipal waste (BMW). A subset of the identified physical contaminant fragments were subsequently reintroduced into the cleaned compost samples and sent to three commercial laboratories for testing in an inter-laboratory trial using the current PAS100:2011 method (AfOR MT PC&S). The trial showed that the 'other' category caused difficulty for all three laboratories with under reporting, particularly of the most common 'other' contaminants (paper and cardboard) and, over-reporting of non-man-made fragments. One laboratory underreported metal contaminant fragments (spiked as silver foil) in three samples. Glass, plastic and stones were variably underreported due to miss-classification or over reported due to contamination with compost (organic) fragments. The results are discussed in the context of global physical contaminant test methods and compost quality assurance schemes.

  8. A phenomenological constitutive model for the nonlinear viscoelastic responses of biodegradable polymers

    KAUST Repository

    Khan, Kamran

    2012-11-09

    We formulate a constitutive framework for biodegradable polymers that accounts for nonlinear viscous behavior under regimes with large deformation. The generalized Maxwell model is used to represent the degraded viscoelastic response of a polymer. The large-deformation, time-dependent behavior of viscoelastic solids is described using an Ogden-type hyperviscoelastic model. A deformation-induced degradation mechanism is assumed in which a scalar field depicts the local state of the degradation, which is responsible for the changes in the material\\'s properties. The degradation process introduces another timescale (the intrinsic material clock) and an entropy production mechanism. Examples of the degradation of a polymer under various loading conditions, including creep, relaxation and cyclic loading, are presented. Results from parametric studies to determine the effects of various parameters on the process of degradation are reported. Finally, degradation of an annular cylinder subjected to pressure is also presented to mimic the effects of viscoelastic arterial walls (the outer cylinder) on the degradation response of a biodegradable stent (the inner cylinder). A general contact analysis is performed. As the stiffness of the biodegradable stent decreases, stress reduction in the stented viscoelastic arterial wall is observed. The integration of the proposed constitutive model with finite element software could help a designer to predict the time-dependent response of a biodegradable stent exhibiting finite deformation and under complex mechanical loading conditions. © 2012 Springer-Verlag Wien.

  9. Biosorption and biodegradation of pyrene by Brevibacillus brevis and cellular responses to pyrene treatment.

    Science.gov (United States)

    Liao, Liping; Chen, Shuona; Peng, Hui; Yin, Hua; Ye, Jinshao; Liu, Zehua; Dang, Zhi; Liu, Zhichen

    2015-05-01

    Biodegradation has been proposed as an effective approach to remove pyrene, however, the information regarding cellular responses to pyrene treatment is limited thus far. In this study, the biodegradation and biosorption of pyrene by Brevibacillus brevis, along with cellular responses caused by pollutant were investigated by means of flow cytometry assay and scanning electron microscopy. The experimental results showed that pyrene was initially adsorbed by B. brevis and subsequently transported and intracellularly degraded. During this process, pyrene removal was primarily dependent on biodegradation. Cell invagination and cell surface corrugation occurred due to pyrene exposure. Nevertheless, cell regrowth after 96h treatment was observed, and the proportion of necrotic cell was only 2.8% after pyrene exposure for 120h, confirming that B. brevis could utilize pyrene as a sole carbon source for growth. The removal and biodegradation amount of pyrene (1mg/L) at 168h were 0.75 and 0.69mg/L, respectively, and the biosorption amount by inactivated cells was 0.41mg/L at this time.

  10. Surfactant-free synthesis of biodegradable, biocompatible, and stimuli-responsive cationic nanogel particles.

    Science.gov (United States)

    Urakami, Hiromitsu; Hentschel, Jens; Seetho, Kellie; Zeng, Hanxiang; Chawla, Kanika; Guan, Zhibin

    2013-10-14

    Nanogels have attracted much attention lately because of their many potential applications, including as nanocarriers for drug and gene delivery. Most nanogels reported previously, however, are not biodegradable, and their synthesis often requires the use of surfactants. Herein we report a surfactant-free method for the preparation of biodegradable, biocompatible, and stimuli-responsive cationic nanogels. The nanogels were synthesized by simply coaservating linear polymer precursors in mixed solvents followed by in situ cross-linking with homobifunctional cross-linkers. The versatility of this approach has been demonstrated by employing two different polymers and various cross-linkers to prepare nanogel particles with diameters ranging from 170 to 220 nm. Specifically, disulfide-containing tetralysine (TetK)- and oligoethylenimine (OEI)-based prepolymers were prepared and the subsequent nanogels were formed by covalently cross-linking the polymer coacervate phase. Nanogel particles are responsive to pH changes, increasing in size and zeta-potential with concomitant lowering of solution pH. Furthermore, as revealed by AFM imaging, nanogel particles were degradable in the presence of glutathione at concentrations similar to those in intracellular environment (10 mM). Both the nanogel and the polymer precursors were determined to exhibit minimal cytotoxicity against fibroblast 3T3 cells by flow cytometric analyses and fluorescent imaging. This study demonstrates a new surfactant-free method for preparing biodegradable, biocompatible, and stimuli-responsive nanogels as potential nanocarriers for the delivery of drugs and genes.

  11. Mathematical modeling of the biodegradation of residual hydrocarbon in a variably-saturated sand column.

    Science.gov (United States)

    Geng, Xiaolong; Boufadel, Michel C; Wrenn, Brian

    2013-04-01

    The biodegradation of heptadecane in five sand columns was modeled using a multiplicative Monod approach. Each column contained 1.0 kg of sand and 2 g of heptadecane, and was supplied with an artificial seawater solution containing nutrients at a flow rate that resulted in unsaturated flow through the column. All nutrients were provided in excess with the exception of nitrate whose influent concentration was 0.1, 0.5, 1.0, 2.5, or 5.0 mg N/L. The experiment was run around 912 h until no measurable oxygen consumption or CO2 production was observed. The residual mass of heptadecane was measured at the end of the experiments and the biodegradation was monitored based on oxygen consumption and CO2 production. Biodegradation kinetic parameters were estimated by fitting the model to experimental data of oxygen, CO2, and residual mass of heptadecane obtained from the two columns having influent nitrate-N concentration of 0.5 and 2.5 mg/L. Noting that the oxygen and CO2 measurements leveled off at around 450 h, we fitted the model to these data for that range. The estimated parameters fell in within the range reported in the literature. In particular, the half-saturation constant for nitrate utilization, [Formula: see text], was estimated to be 0.45 mg N/L, and the yield coefficient was found to be 0.15 mg biomass/mg heptadecane. Using these values, the rest of experimental data from the five columns was predicted, and the model agreed with the observations. There were some consistent discrepancies at large times between the model simulation and observed data in the cases with higher nitrate concentration. One plausible explanation for these differences could be limitation of biodegradation by reduction of the heptadecane-water interfacial area in these columns while the model uses a constant interfacial area.

  12. Optimization of acrylic acid grafting onto polypropylene using response surface methodology and its biodegradability

    Science.gov (United States)

    Mandal, Dev K.; Bhunia, Haripada; Bajpai, Pramod K.; Kushwaha, Jai P.; Chaudhari, Chandrasekhar V.; Dubey, Kumar A.; Varshney, Lalit

    2017-03-01

    Simultaneous radiation grafting was optimized to graft acrylic acid monomer on the polypropylene (PP) films to make them hydrophilic and enhance their biodegradability. Experiments were designed based on full factorial central composite design (response surface methodology) and influence of monomer concentration, radiation dose, inhibitor concentration, solvent concentration on degree of grafting was investigated. The extent of grafting was found to increase with increasing monomer concentration, inhibitor concentration and radiation dose. The targeted 35% grafting could be achieved at optimum condition viz. monomer concentration 12.09 wt%, radiation dose 12.40 kGy, inhibitor concentration 0.07 M and solvent concentration 0.12 M. The grafted PP films at different degrees of grafting were tested for tensile properties and characterized by swelling studies, fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Successful grafting of acrylic acid onto polypropylene films was indicated by FTIR and confirmed quantitatively by determination of carboxylic groups on the film surface. Tensile strength of grafted PP films decreased with increase in degree of grafting. The crystallinity of the grafted PP films was lower than that of PP film as indicated by DSC studies. Grafting of acrylic acid increased the roughness on the surface of PP films indicated by SEM studies. The maximum biodegradability of the 34.55% grafted film was 5.5%.

  13. Acoustic response variability in automotive vehicles

    Science.gov (United States)

    Hills, E.; Mace, B. R.; Ferguson, N. S.

    2009-03-01

    A statistical analysis of a series of measurements of the audio-frequency response of a large set of automotive vehicles is presented: a small hatchback model with both a three-door (411 vehicles) and five-door (403 vehicles) derivative and a mid-sized family five-door car (316 vehicles). The sets included vehicles of various specifications, engines, gearboxes, interior trim, wheels and tyres. The tests were performed in a hemianechoic chamber with the temperature and humidity recorded. Two tests were performed on each vehicle and the interior cabin noise measured. In the first, the excitation was acoustically induced by sets of external loudspeakers. In the second test, predominantly structure-borne noise was induced by running the vehicle at a steady speed on a rough roller. For both types of excitation, it is seen that the effects of temperature are small, indicating that manufacturing variability is larger than that due to temperature for the tests conducted. It is also observed that there are no significant outlying vehicles, i.e. there are at most only a few vehicles that consistently have the lowest or highest noise levels over the whole spectrum. For the acoustically excited tests, measured 1/3-octave noise reduction levels typically have a spread of 5 dB or so and the normalised standard deviation of the linear data is typically 0.1 or higher. Regarding the statistical distribution of the linear data, a lognormal distribution is a somewhat better fit than a Gaussian distribution for lower 1/3-octave bands, while the reverse is true at higher frequencies. For the distribution of the overall linear levels, a Gaussian distribution is generally the most representative. As a simple description of the response variability, it is sufficient for this series of measurements to assume that the acoustically induced airborne cabin noise is best described by a Gaussian distribution with a normalised standard deviation between 0.09 and 0.145. There is generally

  14. Brainstem response and state-trait variables

    Science.gov (United States)

    Gilliland, Kirby

    1988-01-01

    A series of investigations are summarized from a personality research program that have relevance for mental state estimation. Of particular concern are those personality variables that are believed to have either a biological or perceptual basis and their relationship to human task performance and psychophysiology. These variables are among the most robust personality measures and include such dimensions as extraversion-introversion, sensation seeking, and impulsiveness. These dimensions also have the most distinct link to performance and psychophysiology. Through the course of many of these investigations two issues have emerged repeatedly: these personality dimensions appear to mediate mental state, and mental state appears to influence measures of performance or psychophysiology.

  15. Application of response surface analysis for biodegradation of azo reactive textile dye using Aspergillus foetidus.

    Science.gov (United States)

    Sharma, Praveen; Singh, Lakhvinder

    2012-06-01

    This paper reports the application of experimental design methodology for the optimization of decolourization of azo reactive textile dye Remazol Red RR and reduction of chemical oxygen demand (COD) using fungal isolate Aspergillus foetidus. Response surface methodology (RSM), involving central composite design matrix in three most important input variables; temperature, pH and initial dye concentration was employed. A total of 20 experiments were conducted in the study towards the construction of a quadratic model. This demonstrated the benefits of approach in achieving excellent predictions, while minimizing the number of experiments required. Very high regression coefficient between the variables and the responses indicated excellent evaluation of experimental data. Under optimized conditions fungal isolate was capable to decolourize Remazol Red RR up to 86.21% and COD reduction up to 55.43% was achieved during the experimental setup. Enzymatic activity indicated excellent outcome under the optimal process conditions. The experimental values agreed with the predicted ones, indicating suitability of the model and success of RSM approach in optimizing the process.

  16. Variability of site response in Seattle, Washington

    Science.gov (United States)

    Hartzell, S.; Carver, D.; Cranswick, E.; Frankel, A.

    2000-01-01

    Ground motion from local earthquakes and the SHIPS (Seismic Hazards Investigation in Puget Sound) experiment is used to estimate site amplification factors in Seattle. Earthquake and SHIPS records are analyzed by two methods: (1) spectral ratios relative to a nearby site on Tertiary sandstone, and (2) a source/site spectral inversion technique. Our results show site amplifications between 3 and 4 below 5 Hz for West Seattle relative to Tertiary rock. These values are approximately 30% lower than amplification in the Duwamish Valley on artificial fill, but significantly higher than the calculated range of 2 to 2.5 below 5 Hz for the till-covered hills east of downtown Seattle. Although spectral amplitudes are only 30% higher in the Duwamish Valley compared to West Seattle, the duration of long-period ground motion is significantly greater on the artificial fill sites. Using a three-dimensional displacement response spectrum measure that includes the effects of ground-motion duration, values in the Duwamish Valley are 2 to 3 times greater than West Seattle. These calculations and estimates of site response as a function of receiver azimuth point out the importance of trapped surface-wave energy within the shallow, low-velocity, sedimentary layers of the Duwamish Valley. One-dimensional velocity models yield spectral amplification factors close to the observations for till sites east of downtown Seattle and the Duwamish Valley, but underpredict amplifications by a factor of 2 in West Seattle. A two-dimensional finite-difference model does equally well for the till sites and the Duwamish Valley and also yields duration estimates consistent with the observations for the Duwamish Valley. The two-dimensional model, however, still underpredicts amplification in West Seattle by up to a factor of 2. This discrepancy is attributed to 3D effects, including basin-edge-induced surface waves and basin-geometry-focusing effects, caused by the proximity of the Seattle thrust fault

  17. Multi-Wheat-Model Ensemble Responses to Interannual Climate Variability

    Science.gov (United States)

    Ruane, Alex C.; Hudson, Nicholas I.; Asseng, Senthold; Camarrano, Davide; Ewert, Frank; Martre, Pierre; Boote, Kenneth J.; Thorburn, Peter J.; Aggarwal, Pramod K.; Angulo, Carlos

    2016-01-01

    We compare 27 wheat models' yield responses to interannual climate variability, analyzed at locations in Argentina, Australia, India, and The Netherlands as part of the Agricultural Model Intercomparison and Improvement Project (AgMIP) Wheat Pilot. Each model simulated 1981e2010 grain yield, and we evaluate results against the interannual variability of growing season temperature, precipitation, and solar radiation. The amount of information used for calibration has only a minor effect on most models' climate response, and even small multi-model ensembles prove beneficial. Wheat model clusters reveal common characteristics of yield response to climate; however models rarely share the same cluster at all four sites indicating substantial independence. Only a weak relationship (R2 0.24) was found between the models' sensitivities to interannual temperature variability and their response to long-termwarming, suggesting that additional processes differentiate climate change impacts from observed climate variability analogs and motivating continuing analysis and model development efforts.

  18. Human operant learning under concurrent reinforcement of response variability

    NARCIS (Netherlands)

    Maes, J.H.R.; Goot, M.H. van der

    2006-01-01

    This study asked whether the concurrent reinforcement of behavioral variability facilitates learning to emit a difficult target response. Sixty students repeatedly pressed sequences of keys, with an originally infrequently occurring target sequence consistently being followed by positive feedback. T

  19. Promoting Response Variability and Stimulus Generalization in Martial Arts Training

    Science.gov (United States)

    Harding, Jay W.; Wacker, David P.; Berg, Wendy K.; Rick, Gary; Lee, John F.

    2004-01-01

    The effects of reinforcement and extinction on response variability and stimulus generalization in the punching and kicking techniques of 2 martial arts students were evaluated across drill and sparring conditions. During both conditions, the students were asked to demonstrate different techniques in response to an instructor's punching attack.…

  20. Multi-wheat-model ensemble responses to interannual climatic variability

    DEFF Research Database (Denmark)

    Ruane, A C; Hudson, N I; Asseng, S

    2016-01-01

    evaluate results against the interannual variability of growing season temperature, precipitation, and solar radiation. The amount of information used for calibration has only a minor effect on most models' climate response, and even small multi-model ensembles prove beneficial. Wheat model clusters reveal...... common characteristics of yield response to climate; however models rarely share the same cluster at all four sites indicating substantial independence. Only a weak relationship (R2 ≤ 0.24) was found between the models' sensitivities to interannual temperature variability and their response to long...

  1. Variable-ratio versus variable-interval schedules: response rate, resistance to change, and preference.

    Science.gov (United States)

    Nevin, J A; Randolph; Holland, S; McLean, A P

    2001-07-01

    Two experiments asked whether resistance to change depended on variable-ratio as opposed to variable-interval contingencies of reinforcement and the different response rates they establish. In Experiment 1, pigeons were trained on multiple random-ratio random-interval schedules with equated reinforcer rates. Baseline response rates were disrupted by intercomponent food, extinction, and prefeeding. Resistance to change relative to baseline was greater in the interval component, and the difference was correlated with the extent to which baseline response rates were higher in the ratio component. In Experiment 2, pigeons were trained on multiple variable-ratio variable-interval schedules in one half of each session and on concurrent chains in the other half in which the terminal links corresponded to the multiple-schedule components. The schedules were varied over six conditions, including two with equated reinforcer rates. In concurrent chains, preference strongly overmatched the ratio of obtained reinforcer rates. In multiple schedules, relative resistance to response-independent food during intercomponent intervals, extinction, and intercomponent food plus extinction depended on the ratio of obtained reinforcer rates but was less sensitive than was preference. When reinforcer rates were similar, both preference and relative resistance were greater for the variable-interval schedule, and the differences were correlated with the extent to which baseline response rates were higher on the variable-ratio schedule, confirming the results of Experiment 1. These results demonstrate that resistance to change and preference depend in part on response rate as well as obtained reinforcer rate, and challenge the independence of resistance to change and preference with respect to response rate proposed by behavioral momentum theory.

  2. Biodegradable Polymers

    Directory of Open Access Journals (Sweden)

    Isabelle Vroman

    2009-04-01

    Full Text Available Biodegradable materials are used in packaging, agriculture, medicine and other areas. In recent years there has been an increase in interest in biodegradable polymers. Two classes of biodegradable polymers can be distinguished: synthetic or natural polymers. There are polymers produced from feedstocks derived either from petroleum resources (non renewable resources or from biological resources (renewable resources. In general natural polymers offer fewer advantages than synthetic polymers. The following review presents an overview of the different biodegradable polymers that are currently being used and their properties, as well as new developments in their synthesis and applications.

  3. Comparison of the effects of variable site temperatures and constant incubation temperatures on the biodegradation of petroleum hydrocarbons in pilot-scale experiments with field-aged contaminated soils from a cold regions site.

    Science.gov (United States)

    Chang, Wonjae; Whyte, Lyle; Ghoshal, Subhasis

    2011-02-01

    Temporal atmospheric temperature changes during summers at sub-Arctic sites often cause periodic fluctuations in shallow landfarm and surface soil temperatures. However, little information is available on the effect of site-relevant variations on biodegradation performance in cold climates. This study compares the rate and extents of biodegradation of petroleum hydrocarbons at variable site temperatures (1-10 °C) representative of summers at a sub-Arctic site reported previously with those obtained under a constant average temperature of 6 °C. The biodegradation was evaluated in pilot-scale landfarming experiments with field-aged petroleum-contaminated soils shipped from Resolution Island (61°30'N, 65°00'W), Nunavut, Canada. Under the variable site temperature conditions biodegradation rate constants of semi- (F2) and non-volatile (F3) hydrocarbon fractions were enhanced by over a factor of two during the 60-d experiment, compared to the constant temperature mode. The decrease in total petroleum hydrocarbons (TPH) under the variable site temperature mode was 55% compared to only 19% under the constant average temperature mode. The enhanced biodegradation is attributable to the non-linear acceleration of microbial activity between 4.7 and 10°C and faster growth of indigenous hydrocarbon-degrading microbial populations. The first-order biodegradation rate constants of 0.018, 0.024 and 0.016 d(-1) for TPH, F2 and F3 fractions at the variable site temperature were in agreement with those determined by an on-site experiment at the same site.

  4. Role of self-assembly coated Er(3+): YAlO3/TiO2 in intimate coupling of visible-light-responsive photocatalysis and biodegradation reactions.

    Science.gov (United States)

    Dong, Shanshan; Dong, Shuangshi; Tian, Xiadi; Xu, Zhengxue; Ma, Dongmei; Cui, Bin; Ren, Nanqi; Rittmann, Bruce E

    2016-01-25

    Conventionally used ultraviolet light can result in dissolved organic carbon (DOC) increasing and biofilm damage in intimate coupling of photocatalysis and biodegradation (ICPB). Visible-light-responsive photocatalysis offers an alternative for achieving ICPB. In this study, composite-cubes were developed using self-assembly to coat a thin and even layer of visible-light-responsive photocatalyst (Er(3+): YAlO3/TiO2) on sponge-type carriers, followed by biofilm cultivation. The degradations of phenol (50 mg L(-1)) were compared for four protocols in circulating beds: adsorption (AD), visible-light-responsive photocatalysis (VPC), biodegradation (B), and intimately coupled visible-light-responsive photocatalysis and biodegradation (VPCB). The phenol and DOC removal efficiencies using VPCB in 16 h were 99.8% and 65.2%, respectively, i.e., higher than those achieved using VPC (71.6% and 50.0%) or B (99.4% and 58.2%). The phenol removal of 96.3% could be obtained even after 3 additional cycles. The 6.17-min intermediate detected by HPLC, continuously accumulated for VPC, appeared at 1-6 h and then was completely removed for VPCB in 10 h. ICPB was further illustrated in that most of the biofilm was protected in the carrier interiors, with less protection on the carrier exterior in VPCB. A self-regulation mechanism that helped photocatalyst exposure to visible-light irradiation was identified, promoting the combined photocatalysis and biodegradation.

  5. Multi-wheat-model ensemble responses to interannual climate variability

    NARCIS (Netherlands)

    Ruane, Alex C.; Hudson, Nicholas I.; Asseng, Senthold; Camarrano, Davide; Ewert, Frank; Martre, Pierre; Boote, Kenneth J.; Thorburn, Peter J.; Aggarwal, Pramod K.; Angulo, Carlos; Basso, Bruno; Bertuzzi, Patrick; Biernath, Christian; Brisson, Nadine; Challinor, Andrew J.; Doltra, Jordi; Gayler, Sebastian; Goldberg, Richard; Grant, Robert F.; Heng, Lee; Hooker, Josh; Hunt, Leslie A.; Ingwersen, Joachim; Izaurralde, Roberto C.; Kersebaum, Kurt Christian; Kumar, Soora Naresh; Müller, Christoph; Nendel, Claas; O'Leary, Garry; Olesen, Jørgen E.; Osborne, Tom M.; Palosuo, Taru; Priesack, Eckart; Ripoche, Dominique; Rötter, Reimund P.; Semenov, Mikhail A.; Shcherbak, Iurii; Steduto, Pasquale; Stöckle, Claudio O.; Stratonovitch, Pierre; Streck, Thilo; Supit, Iwan; Tao, Fulu; Travasso, Maria; Waha, Katharina; Wallach, Daniel; White, Jeffrey W.; Wolf, Joost

    2016-01-01

    We compare 27 wheat models' yield responses to interannual climate variability, analyzed at locations in Argentina, Australia, India, and The Netherlands as part of the Agricultural Model Intercomparison and Improvement Project (AgMIP) Wheat Pilot. Each model simulated 1981-2010 grain yield, and

  6. Heart Rate Variability: Effect of Exercise Intensity on Postexercise Response

    Science.gov (United States)

    James, David V. B.; Munson, Steven C.; Maldonado-Martin, Sara; De Ste Croix, Mark B. A.

    2012-01-01

    The purpose of the present study was to investigate the influence of two exercise intensities (moderate and severe) on heart rate variability (HRV) response in 16 runners 1 hr prior to (-1 hr) and at +1 hr, +24 hr, +48 hr, and +72 hr following each exercise session. Time domain indexes and a high frequency component showed a significant decrease…

  7. Cortical Variability in the Sensory-Evoked Response in Autism

    Science.gov (United States)

    Haigh, Sarah M.; Heeger, David J.; Dinstein, Ilan; Minshew, Nancy; Behrmann, Marlene

    2015-01-01

    Previous findings have shown that individuals with autism spectrum disorder (ASD) evince greater intra-individual variability (IIV) in their sensory-evoked fMRI responses compared to typical control participants. We explore the robustness of this finding with a new sample of high-functioning adults with autism. Participants were presented with…

  8. Stimuli-Responsive Biodegradable Hyperbranched Polymer-Gadolinium Conjugates as Efficient and Biocompatible Nanoscale Magnetic Resonance Imaging Contrast Agents.

    Science.gov (United States)

    Sun, Ling; Li, Xue; Wei, Xiaoli; Luo, Qiang; Guan, Pujun; Wu, Min; Zhu, Hongyan; Luo, Kui; Gong, Qiyong

    2016-04-27

    The efficacy and biocompatibility of nanoscale magnetic resonance imaging (MRI) contrast agents depend on optimal molecular structures and compositions. Gadolinium [Gd(III)] based dendritic macromolecules with well-defined and tunable nanoscale sizes are excellent candidates as multivalent MRI contrast agents. Here, we propose a novel alternate preparation of biodegradable hyperbranched polymer-gadolinium conjugates via a simple strategy and report potentially efficient and biocompatible nanoscale MRI contrast agents for cancer diagnosis. The enzyme-responsive hyperbranched poly(oligo-(ethylene glycol) methacrylate)-gadolinium conjugate (HB-POEGMA-Gd) was prepared via one-step reversible addition-fragmentation chain transfer (RAFT) polymerization and Gd(III) chelating, and the cRGDyK functionalized polymer (HB-POEGMA-cRGD-Gd) was obtained via click chemistry. By using an enzyme similar to lysosomal cathepsin B, hyperbranched conjugates of high molecular weights (MW) (180 and 210 kDa) and nanoscale sizes (38 and 42 nm) were degraded into low MW (25 and 30 kDa) and smaller products (4.8 and 5.2 nm) below the renal threshold. Conjugate-based nanoscale systems had three-fold more T1 relaxivity compared to clinical agent diethylenediaminepentaacetic acid (DTPA)-Gd. Animal studies with the nanoscale system offered greater tumor accumulation and enhanced signal intensity (SI) in mouse U87 tumors of which the greatest activity was conferred by the cRGDyK moiety functionalized hyperbranched conjugate. In vitro cytotoxicity, hemocompatibility and in vivo toxicity studies confirmed no adverse events. This design strategy for multifunctional Gd(III)-labeled biodegradable dendritic macromolecules may have significant potential as future efficient, biocompatible polymeric nanoscale MRI diagnostic contrast agents for cancer.

  9. Biosorption and biodegradation of Acid Orange 7 by Enterococcus faecalis strain ZL: optimization by response surface methodological approach.

    Science.gov (United States)

    Lim, Chi Kim; Bay, Hui Han; Aris, Azmi; Abdul Majid, Zaiton; Ibrahim, Zaharah

    2013-07-01

    Reactive dyes account for one of the major sources of dye wastes in textile effluent. In this study, decolorization of the monoazo dye, Acid Orange 7 (AO7) by the Enterococcus faecalis strain ZL that isolated from a palm oil mill effluent treatment plant has been investigated. Decolorization efficiency of azo dye is greatly affected by the types of nutrients and the size of inoculum used. In this work, one-factor-at-a-time (method and response surface methodology (RSM) was applied to optimize these operational factors and also to study the combined interaction between them. Analysis of AO7 decolorization was done using Fourier transform infrared (FTIR) spectroscopy, desorption study, UV-Vis spectral analysis, field emission scanning electron microscopy (FESEM), and high performance liquid chromatography (HPLC). The optimum condition via RSM for the color removal of AO7 was found to be as follows: yeast extract, 0.1% w/v, glycerol concentration of 0.1% v/v, and inoculum density of 2.5% v/v at initial dye concentration of 100 mg/L at 37 °C. Decolorization efficiency of 98% was achieved in only 5 h. The kinetic of AO7 decolorization was found to be first order with respect to dye concentration with a k value of 0.87/h. FTIR, desorption study, UV-Vis spectral analysis, FESEM, and HPLC findings indicated that the decolorization of AO7 was mainly due to the biosorption as well as biodegradation of the bacterial cells. In addition, HPLC analyses also showed the formation of sulfanilic acid as a possible degradation product of AO7 under facultative anaerobic condition. This study explored the ability of E. faecalis strain ZL in decolorizing AO7 by biosorption as well as biodegradation process.

  10. Hydrocarbon biodegradation and dynamic laser speckle for detecting chemotactic responses at low bacterial concentration.

    Science.gov (United States)

    Nisenbaum, Melina; Sendra, Gonzalo Hernán; Gilbert, Gastón Alfredo Cerdá; Scagliola, Marcelo; González, Jorge Froilán; Murialdo, Silvia Elena

    2013-03-01

    We report on the biodegradation of pure hydrocarbons and chemotaxis towards these compounds by an isolated chlorophenol degrader, Pseudomonas strain H. The biochemical and phylogenetic analysis of the 16S rDNA sequence identified Pseudomonas strain H as having 99.56% similarity with P. aeruginosa PA01. This strain was able to degrade n-hexadecane, 1-undecene, 1-nonene, 1-decene, 1-dodecene and kerosene. It grew in the presence of 1-octene, while this hydrocarbons is toxic to other hydrocarbons degraders. Pseudomonas strain H was also chemotactic towards n-hexadecane, kerosene, 1-undecene and 1-dodecene. These results show that this Pseudomonas strain H is an attractive candidate for hydrocarbon-containing wastewater bioremediation in controlled environments. Since the classical standard techniques for detecting chemotaxis are not efficient at low bacterial concentrations, we demonstrate the use of the dynamic speckle laser method, which is simple and inexpensive, to confirm bacterial chemotaxis at low cell concentrations (less than 10(5) colony-forming unit per millilitre (CFU/mL)) when hydrocarbons are the attractants.

  11. Hydrocarbon biodegradation and dynamic laser speckle for detecting chemotactic responses at low bacterial concentration

    Institute of Scientific and Technical Information of China (English)

    Melina Nisenbaum; Gonzalo Hernán Sendra; Gastón Alfredo Cerdá Gilbert; Marcelo Scagliola; Jorge Froilán González; Silvia Elena Murialdo

    2013-01-01

    We report on the biodegradation of pure hydrocarbons and chemotaxis towards these compounds by an isolated chlorophenol degrader,Pseudomonas strain H.The biochemical and phylogenetic analysis of the 16S rDNA sequence identified Pseudomonas strain H as having 99.56% similarity with P.aeruginosa PA01.This strain was able to degrade n-hexadecane,1-undecene,1-nonene,1-decene,1-dodecene and kerosene.It grew in the presence of 1-octene,while this hydrocarbons is toxic to other hydrocarbons degraders.Pseudomonas strain H was also chemotactic towards n-hexadecane,kerosene,1-undecene and 1-dodecene.These results show that this Pseudomonas strain H is an attractive candidate for hydrocarbon-containing wastewater bioremediation in controlled environments.Since the classical standard techniques for detecting chemotaxis are not efficient at low bacterial concentrations,we demonstrate the use of the dynamic speckle laser method,which is simple and inexpensive,to confirm bacterial chemotaxis at low cell concentrations (less than 105 colony-forming unit per millilitre (CFU/mL)) when hydrocarbons are the attractants.

  12. Optimization of Process Variables by Response Surface Methodology

    Directory of Open Access Journals (Sweden)

    Kashipeta Ravinder

    2015-12-01

    Full Text Available In the present study optimisation of the growth medium for the production of Cyclodextrin glucanotransferase (CGTase was carried out using response surface methodology. Four important parameters namely starch, yeast extract, K2HPO4 and MgSO4 concentrations were selected as the independent variables and the enzyme activity (CGTase activity U/mL was the dependent response variable. Each of these independent variables was studied at five different levels as per central composite design (CCD in four variables with a total of 28 experimental runs. The optimal calculated values of tested variables for maximal production of CGTase were found to be comprised of: starch, 2.16 %; yeast extract, 0.6 %; K2HPO4, 0.62 %; MgSO4, 0.04 % with a predicted CGTase activity of 150 U/ml. These predicted optimal parameters were tested in the laboratory and the final CGTase activity obtained was very close to the predicted value at 148.2 U/ml.

  13. Biodegradable thermogels.

    Science.gov (United States)

    Park, Min Hee; Joo, Min Kyung; Choi, Bo Gyu; Jeong, Byeongmoon

    2012-03-20

    All living creatures respond to external stimuli. Similarly, some polymers undergo conformational changes in response to changes in temperature, pH, magnetic field, electrical field, or the wavelength of light. In one type of stimuli-responsive polymer, thermogel polymers, the polymer aqueous solution undergoes sol-to-gel transition as the temperature increases. Drugs or cells can be mixed into the polymer aqueous solution when it is in its lower viscosity solution state. After injection of the solution into a target site, heating prompts the formation of a hydrogel depot in situ, which can then act as a drug releasing system or a cell growing matrix. In this Account, we describe key materials developed in our laboratory for the construction of biodegradable thermogels. We particularly emphasize recently developed polypeptide-based materials where the secondary structure and nanoassembly play an important role in the determining the material properties. This Account will provide insights for controlling parameters, such as the sol-gel transition temperature, gel modulus, critical gel concentration, and degradability of the polymer, when designing a new thermogel system for a specific biomedical application. By varying the stereochemistry of amino acids in polypeptides, the molecular weight of hydrophobic/hydrophilic blocks, the composition of the polypeptides, the hydrophobic end-capping of the polypeptides, and the microsequences of a block copolymer, we have controlled the thermosensitivity and nanoassembly patterns of the polymers. We have investigated a series of thermogel biodegradable polymers. Polymers such as poly(lactic acid-co-glycolic acid), polycaprolactone, poly(trimethylene carbonate), polycyanoacrylate, sebacic ester, polypeptide were used as hydrophobic blocks, and poly(ethylene glycol) and poly(vinyl pyrrolidone) were used as hydrophilic blocks. To prepare a polymer sensitive to pH and temperature, carboxylic acid or amine groups were introduced

  14. Qigong Effects on Heart Rate Variability and Peripheral Vasomotor Responses.

    Science.gov (United States)

    Chang, Mei-Ying

    2015-11-01

    Population aging is occurring worldwide, and preventing cardiovascular event in older people is a unique challenge. The aim of this study was to examine the effects of a 12-week qigong (eight-form moving meditation) training program on the heart rate variability and peripheral vasomotor response of middle-aged and elderly people in the community. This was a quasi-experimental study that included the pre-test, post-test, and nonequivalent control group designs. Seventy-seven participants (experimental group = 47; control group = 30) were recruited. The experimental group performed 30 min of eight-form moving meditation 3 times per week for 12 weeks, and the control group continued their normal daily activities. After 12 weeks, the interaction effects indicated that compared with the control group, the experimental group exhibited significantly improved heart rate variability and peripheral vasomotor responses.

  15. Decreased heart rate variability responses during early postoperative mobilization

    DEFF Research Database (Denmark)

    Jans, Øivind; Brinth, Louise; Kehlet, Henrik;

    2015-01-01

    BACKGROUND: Intact orthostatic blood pressure regulation is essential for early mobilization after surgery. However, postoperative orthostatic hypotension and intolerance (OI) may delay early ambulation. The mechanisms of postoperative OI include impaired vasopressor responses relating to postope......BACKGROUND: Intact orthostatic blood pressure regulation is essential for early mobilization after surgery. However, postoperative orthostatic hypotension and intolerance (OI) may delay early ambulation. The mechanisms of postoperative OI include impaired vasopressor responses relating...... to postoperative autonomic dysfunction. Thus, based on a previous study on haemodynamic responses during mobilization before and after elective total hip arthroplasty (THA), we performed secondary analyses of heart rate variability (HRV) and aimed to identify possible abnormal postoperative autonomic responses...... in relation to postural change. METHODS: A standardized mobilization protocol before, 6 and 24 h after surgery was performed in 23 patients scheduled for elective THA. Beat-to-beat arterial blood pressure was measured by photoplethysmography and HRV was derived from pulse wave interbeat intervals and analysed...

  16. pH-responsive biodegradable micelles based on acid-labile polycarbonate hydrophobe: synthesis and triggered drug release.

    Science.gov (United States)

    Chen, Wei; Meng, Fenghua; Li, Feng; Ji, Shun-Jun; Zhong, Zhiyuan

    2009-07-13

    pH-responsive biodegradable micelles were prepared from block copolymers comprising of a novel acid-labile polycarbonate hydrophobe and poly(ethylene glycol) (PEG). Two new cyclic aliphatic carbonate monomers, mono-2,4,6-trimethoxybenzylidene-pentaerythritol carbonate (TMBPEC, 2a) and mono-4-methoxybenzylidene-pentaerythritol carbonate (MBPEC, 2b) were designed and successfully synthesized via a two-step procedure. The ring-opening polymerization of 2a or 2b in the presence of methoxy PEG in dichloromethane at 50 °C using zinc bis[bis(trimethylsilyl)amide] as a catalyst yielded the corresponding block copolymers PEG-PTMBPEC (3a) or PEG-PMBPEC (3b) with low polydispersities (PDI 1.03-1.04). The copolymerization of D,L-lactide (DLLA) and 2a under otherwise the same conditions could also proceed smoothly to afford PEG-P(TMBPEC-co-DLLA) (3c) block copolymer. These block copolymers readily formed micelles in water with sizes of about 120 nm as determined by dynamic light scattering (DLS). The hydrolysis of the acetals of the polycarbonate was investigated using UV/vis spectroscopy. The results showed that the acetals of micelles 3a, while stable at pH 7.4 are prone to rapid hydrolysis at mildly acidic pH of 4.0 and 5.0, with a half-life of 1 and 6.5 h, respectively. The acetal hydrolysis resulted in significant swelling of micelles, as a result of change of hydrophobic polycarbonate to hydrophilic polycarbonate. In comparison, the acetals of PMBPEC of micelles 3b displayed obviously slower hydrolysis at the same pH. Both paclitaxel and doxorubicin could be efficiently encapsulated into micelles 3a achieving high drug loading content (13.0 and 11.7 wt %, respectively). The in vitro release studies showed clearly a pH dependent release behavior, that is, significantly faster drug release at mildly acidic pH of 4.0 and 5.0 compared to physiological pH. These pH-responsive biodegradable micelles are promising as smart nanovehicles for targeted delivery of anticancer drugs.

  17. Human Responses to Climate Variability: The Case of South Africa

    Science.gov (United States)

    Oppenheimer, M.; Licker, R.; Mastrorillo, M.; Bohra-Mishra, P.; Estes, L. D.; Cai, R.

    2014-12-01

    Climate variability has been associated with a range of societal and individual outcomes including migration, violent conflict, changes in labor productivity, and health impacts. Some of these may be direct responses to changes in mean temperature or precipitation or extreme events, such as displacement of human populations by tropical cyclones. Others may be mediated by a variety of biological, social, or ecological factors such as migration in response to long-term changes in crops yields. Research is beginning to elucidate and distinguish the many channels through which climate variability may influence human behavior (ranging from the individual to the collective, societal level) in order to better understand how to improve resilience in the face of current variability as well as future climate change. Using a variety of data sets from South Africa, we show how climate variability has influenced internal (within country) migration in recent history. We focus on South Africa as it is a country with high levels of internal migration and dramatic temperature and precipitation changes projected for the 21st century. High poverty rates and significant levels of rain-fed, smallholder agriculture leave large portions of South Africa's population base vulnerable to future climate change. In this study, we utilize two complementary statistical models - one micro-level model, driven by individual and household level survey data, and one macro-level model, driven by national census statistics. In both models, we consider the effect of climate on migration both directly (with gridded climate reanalysis data) and indirectly (with agricultural production statistics). With our historical analyses of climate variability, we gain insights into how the migration decisions of South Africans may be influenced by future climate change. We also offer perspective on the utility of micro and macro level approaches in the study of climate change and human migration.

  18. Clopidogrel Response Variability: Review of the Literature and Practical Considerations.

    Science.gov (United States)

    Oliphant, Carrie S; Trevarrow, Brian J; Dobesh, Paul P

    2016-02-01

    Dual antiplatelet therapy with aspirin and a P2Y12 inhibitor is standard therapy following acute coronary syndrome and percutaneous coronary intervention. Despite the use of potent antiplatelet agents, vascular events continue to occur. Lack of response to clopidogrel therapy has been widely investigated using various methods of platelet function testing. These studies have consistently found an association between poor clopidogrel response and an increased risk of vascular events. Strategies to overcome this problem include higher clopidogrel doses or the use of an alternative P2Y12 agent. To date, the majority of studies investigating tailored antiplatelet therapy have failed to show any reduction in clinical events likely due to the low-risk population studied. Despite this lack of benefit from altering therapy, platelet function testing may be done in certain patient populations. Patients at high risk of deleterious outcomes from stent thrombosis may be an appropriate patient population for platelet function testing to ensure adequate response to therapy. In addition, emerging data suggests a potential role for platelet function testing to assess for bleeding risk. The purpose of this article is to review the key studies demonstrating response variability to clopidogrel therapy, strategies to overcome variability, and practical considerations for the clinician.

  19. Enhancement of the optical response in a biodegradable polymer/azo-dye film by the addition of carbon nanotubes

    Science.gov (United States)

    Díaz Costanzo, Guadalupe; Ribba, Laura; Goyanes, Silvia; Ledesma, Silvia

    2014-04-01

    A new biodegradable photoresponsive material was developed using poly(lactic acid) (PLA) as the matrix material and Disperse Orange 3 (DO3) as photoisomerizable azo-dye. It was observed that the addition of multi-walled carbon nanotubes (MWCNTs) leads to a new phenomenon consisting of an enhancement of the optical anisotropy in a wide range of temperatures. In particular, the optical anisotropy increases 100% at room temperature. Moreover, the material containing MWCNTs shows a faster optical response that is evidenced as an increase in the growth rate of optical anisotropy. Spectroscopic data is provided to study the interaction among DO3, MWCNTs and PLA. The enhancement of optical anisotropy obtained with the addition of MWCNTs was related to the glass transition temperature (Tg) of each material. Maximum optical anisotropy was obtained 15 °C below the Tg for both materials. Results are interpreted in terms of the interactions among DO3, MWCNTs and PLA and the packing density of the dye into the polymer chains. In memory of Professor Iñaki Mondragon.

  20. Variable-amplitude oscillatory shear response of amorphous materials

    Science.gov (United States)

    Perchikov, Nathan; Bouchbinder, Eran

    2014-06-01

    Variable-amplitude oscillatory shear tests are emerging as powerful tools to investigate and quantify the nonlinear rheology of amorphous solids, complex fluids, and biological materials. Quite a few recent experimental and atomistic simulation studies demonstrated that at low shear amplitudes, an amorphous solid settles into an amplitude- and initial-conditions-dependent dissipative limit cycle, in which back-and-forth localized particle rearrangements periodically bring the system to the same state. At sufficiently large shear amplitudes, the amorphous system loses memory of the initial conditions, exhibits chaotic particle motions accompanied by diffusive behavior, and settles into a stochastic steady state. The two regimes are separated by a transition amplitude, possibly characterized by some critical-like features. Here we argue that these observations support some of the physical assumptions embodied in the nonequilibrium thermodynamic, internal-variables based, shear-transformation-zone model of amorphous viscoplasticity; most notably that "flow defects" in amorphous solids are characterized by internal states between which they can make transitions, and that structural evolution is driven by dissipation associated with plastic deformation. We present a rather extensive theoretical analysis of the thermodynamic shear-transformation-zone model for a variable-amplitude oscillatory shear protocol, highlighting its success in accounting for various experimental and simulational observations, as well as its limitations. Our results offer a continuum-level theoretical framework for interpreting the variable-amplitude oscillatory shear response of amorphous solids and may promote additional developments.

  1. A Variable Response Inconsistency Scale and a True Response Inconsistency Scale for the Jesness Inventory.

    Science.gov (United States)

    Pinsoneault, Terry B.

    1998-01-01

    Inconsistent item-pair Variable Response Inconsistency (VRIN) and True Response Inconsistency (TRIN) scales were developed for the Jesness Inventory using 500 male and female delinquents to detect random and acquiescent sets. Specificities above 0.90 showed sensitivities up to 0.89 for VRIN and 0.85 and 0.62 for TRIN. Predictive power and overall…

  2. Redox-responsive biodegradable PEGylated nanographene oxide for efficiently chemo-photothermal therapy: a comparative study with non-biodegradable PEGylated nanographene oxide.

    Science.gov (United States)

    Xiong, Honglian; Guo, Zhouyi; Zhang, Wen; Zhong, Huiqing; Liu, Songhao; Ji, Yanhong

    2014-09-05

    Nanographene oxide (NGO) with a non-sheddable poly(ethylene glycol) (PEG) coating has been used for chemo-photothermal therapy. However, the drug release of PEGylated NGO (NGO-PEG) with an amine bond is adversely affected by the diffusion barrier effect of PEG shells. Here, we developed a simple new method for the preparation of biodegradable PEGylated NGO conjugates (NGO-SS-PEG) with cleavable disulfide bonds for rapid drug release and more efficiently chemo-photothermal therapy. The glutathione (GSH)-induced and photothermal-mediated intracellular release of doxorubicin (DOX) from NGO-SS-PEG was studied in A549 cells using confocal laser scanning microscopy and flow cytometry analysis. In vivo cytotoxicity experiments were performed on chemo-photothermal therapy. Furthermore, we presented a comparative study of intracellular drug release and biological efficacy between NGO-SS-PEG/DOX and NGO-PEG/DOX. The results demonstrated that the rapid drug release from the NGO-SS-PEG conjugates with sheddable PEG was triggered upon the stimulus of high GSH levels inside A549 cells. Interesting, the DOX release mediated by the photothermal effect from the NGO-SS-PEG conjugates was found to be more obvious than that for NGO-PEG. Additionally, NGO-SS-PEG showed a higher efficacy than NGO-PEG for anti-tumor therapy compared with NGO-PEG. Thus, NGO-SS-PEG can improve therapeutic efficacy and is an attractive drug nanocarrier.

  3. Estimation of road profile variability from measured vehicle responses

    Science.gov (United States)

    Fauriat, W.; Mattrand, C.; Gayton, N.; Beakou, A.; Cembrzynski, T.

    2016-05-01

    When assessing the statistical variability of fatigue loads acting throughout the life of a vehicle, the question of the variability of road roughness naturally arises, as both quantities are strongly related. For car manufacturers, gathering information on the environment in which vehicles evolve is a long and costly but necessary process to adapt their products to durability requirements. In the present paper, a data processing algorithm is proposed in order to estimate the road profiles covered by a given vehicle, from the dynamic responses measured on this vehicle. The algorithm based on Kalman filtering theory aims at solving a so-called inverse problem, in a stochastic framework. It is validated using experimental data obtained from simulations and real measurements. The proposed method is subsequently applied to extract valuable statistical information on road roughness from an existing load characterisation campaign carried out by Renault within one of its markets.

  4. Taking the pulse of mountains: Ecosystem responses to climatic variability

    Science.gov (United States)

    Fagre, D.B.; Peterson, D.L.; Hessl, A.E.

    2003-01-01

    An integrated program of ecosystem modeling and field studies in the mountains of the Pacific Northwest (U.S.A.) has quantified many of the ecological processes affected by climatic variability. Paleoecological and contemporary ecological data in forest ecosystems provided model parameterization and validation at broad spatial and temporal scales for tree growth, tree regeneration and treeline movement. For subalpine tree species, winter precipitation has a strong negative correlation with growth; this relationship is stronger at higher elevations and west-side sites (which have more precipitation). Temperature affects tree growth at some locations with respect to length of growing season (spring) and severity of drought at drier sites (summer). Furthermore, variable but predictable climate-growth relationships across elevation gradients suggest that tree species respond differently to climate at different locations, making a uniform response of these species to future climatic change unlikely. Multi-decadal variability in climate also affects ecosystem processes. Mountain hemlock growth at high-elevation sites is negatively correlated with winter snow depth and positively correlated with the winter Pacific Decadal Oscillation (PDO) index. At low elevations, the reverse is true. Glacier mass balance and fire severity are also linked to PDO. Rapid establishment of trees in subalpine ecosystems during this century is increasing forest cover and reducing meadow cover at many subalpine locations in the western U.S.A. and precipitation (snow depth) is a critical variable regulating conifer expansion. Lastly, modeling potential future ecosystem conditions suggests that increased climatic variability will result in increasing forest fire size and frequency, and reduced net primary productivity in drier, east-side forest ecosystems. As additional empirical data and modeling output become available, we will improve our ability to predict the effects of climatic change

  5. Congruent responses to weather variability in high arctic herbivores.

    Science.gov (United States)

    Stien, Audun; Ims, Rolf A; Albon, Steve D; Fuglei, Eva; Irvine, R Justin; Ropstad, Erik; Halvorsen, Odd; Langvatn, Rolf; Loe, Leif Egil; Veiberg, Vebjørn; Yoccoz, Nigel G

    2012-12-23

    Assessing the role of weather in the dynamics of wildlife populations is a pressing task in the face of rapid environmental change. Rodents and ruminants are abundant herbivore species in most Arctic ecosystems, many of which are experiencing particularly rapid climate change. Their different life-history characteristics, with the exception of their trophic position, suggest that they should show different responses to environmental variation. Here we show that the only mammalian herbivores on the Arctic islands of Svalbard, reindeer (Rangifer tarandus) and sibling voles (Microtus levis), exhibit strong synchrony in population parameters. This synchrony is due to rain-on-snow events that cause ground ice and demonstrates that climate impacts can be similarly integrated and expressed in species with highly contrasting life histories. The finding suggests that responses of wildlife populations to climate variability and change might be more consistent in Polar regions than elsewhere owing to the strength of the climate impact and the simplicity of the ecosystem.

  6. On the Primacy of Molecular Processes in Determining Response Rates under Variable-Ratio and Variable-Interval Schedules

    Science.gov (United States)

    Tanno, Takayuki; Sakagami, Takayuki

    2008-01-01

    This study focused on variables that may account for response-rate differences under variable-ratio (VR) and variable-interval (VI) schedules of reinforcement. Four rats were exposed to VR, VI, tandem VI differential- reinforcement-of-high-rate, regulated-probability-interval, and negative-feedback schedules of reinforcement that provided the same…

  7. Interpatient Variability in Dexmedetomidine Response: A Survey of the Literature

    Directory of Open Access Journals (Sweden)

    Samantha F. Holliday

    2014-01-01

    Full Text Available Fifty-five thousand patients are cared for in the intensive care unit (ICU daily with sedation utilized to reduce anxiety and agitation while optimizing comfort. The Society of Critical Care Medicine (SCCM released updated guidelines for management of pain, agitation, and delirium in the ICU and recommended nonbenzodiazepines, such as dexmedetomidine and propofol, as first line sedation agents. Dexmedetomidine, an alpha-2 agonist, offers many benefits yet its use is mired by the inability to consistently achieve sedation goals. Three hypotheses including patient traits/characteristics, pharmacokinetics in critically ill patients, and clinically relevant genetic polymorphisms that could affect dexmedetomidine response are presented. Studies in patient traits have yielded conflicting results regarding the role of race yet suggest that dexmedetomidine may produce more consistent results in less critically ill patients and with home antidepressant use. Pharmacokinetics of critically ill patients are reported as similar to healthy individuals yet wide, unexplained interpatient variability in dexmedetomidine serum levels exist. Genetic polymorphisms in both metabolism and receptor response have been evaluated in few studies, and the results remain inconclusive. To fully understand the role of dexmedetomidine, it is vital to further evaluate what prompts such marked interpatient variability in critically ill patients.

  8. Martian ionosphere response to solar wind variability during solar minimum

    Science.gov (United States)

    Sanchez-Cano, Beatriz; Lester, Mark; Witasse, Olivier; Mays, M. Leila; Hall, Benjamin E. S.; Milan, Stephen E.; Cartacci, Marco; Blelly, Pierre-Louis; Andrews, David; Opgenoorth, Hermann; Odstrcil, Dusan

    2016-04-01

    Solar cycle variations in solar radiation create notable density changes in the Martian ionosphere. In addition to this long-term variability, there are numerous short-term and non-recurrent solar events that hit Mars which need to be considered, such as Interplanetary Coronal Mass Ejections (ICMEs), Co-Rotation Interaction Regions (CIRs), solar flares, or solar wind high speed streams. The response of the Martian plasma system to each of these events is often unusual, especially during the long period of extreme low solar activity in 2008 and 2009. This work shows the long-term solar cycle impact on the ionosphere of Mars using data from The Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS), and The Analyzer of Space Plasma and Energetic Atoms (ASPERA-3), and with empirical and numerical models on Mars Express. Particular attention is given to the different ionospheric responses observed during the last, extended solar minimum. Mars' ionospheric response followed a similar pattern to the response observed in the Earth's ionosphere, despite the large differences related to the inner-origin of the magnetic field of both planets. The ionospheric temperature was cooler, the topside scale height was smaller and almost constant with altitude, the secondary ionospheric layer practically disappeared and the whole atmospheric total electron content (TEC) suffered an extreme reduction of about 30-40%, not predicted before by models. Moreover, there is a larger probability for the induced magnetic field to be present in the ionosphere, than in other phases of the solar cycle. The short-term variability is also addressed with the study of an ICME followed by a fast stream that hit Mars in March 2008, where solar wind data are provided by ACE and STEREO-B and supported by simulations using the WSA-ENLIL Model. The solar wind conditions lead to the formation of a CIR centred on the interface of the fast and the slow solar wind streams. Mars' system reacted to

  9. Lung toxicity of biodegradable nanoparticles.

    Science.gov (United States)

    Fattal, Elias; Grabowski, Nadége; Mura, Simona; Vergnaud, Juliette; Tsapis, Nicolas; Hillaireau, Hervé

    2014-10-01

    Biodegradable nanoparticles exhibit high potentialities for local or systemic drug delivery through lung administration making them attractive as nanomedicine carriers. However, since particulate matter or some inorganic manufactured nanoparticles exposed to lung cells have provoked cytotoxic effects, inflammatory and oxidative stress responses, it becomes important to investigate nanomedicine toxicity towards the lungs. This is the reason why, in the present review, the behavior of biodegradable nanoparticles towards the different parts of the respiratory tract as well as the toxicological consequences, measured on several models in vitro, ex vivo or in vivo, are described. Taken all together, the different studies carried out so far conclude on no or slight toxicity of biodegradable nanoparticles.

  10. Water-Responsive Shape Recovery Induced Buckling in Biodegradable Photo-Cross-Linked Poly(ethylene glycol) (PEG) Hydrogel.

    Science.gov (United States)

    Salvekar, Abhijit Vijay; Huang, Wei Min; Xiao, Rui; Wong, Yee Shan; Venkatraman, Subbu S; Tay, Kiang Hiong; Shen, Ze Xiang

    2017-02-21

    shape memory embolization plug for temporary vascular occlusion. The plug consists of a composite with a poly(dl-lactide-co-glycolide) (PLGA) core (loaded with radiopaque filler) and cross-linked poly(ethylene glycol) (PEG) hydrogel outer layer. The device can be activated by body fluid (or water) after about 2 min of immersion in water. The whole occlusion process is completed within a few dozens of seconds. The underlying mechanism is water-responsive shape recovery induced buckling, which occurs in an expeditious manner within a short time period and does not require complete hydration of the whole hydrogel. In this paper, we experimentally and analytically investigate the water-activated shape recovery induced buckling in this biodegradable PEG hydrogel to understand the fundamentals in precisely controlling the buckling time. The molecular mechanism responsible for the water-induced SME in PEG hydrogel is also elucidated. The original diameter and amount of prestretching are identified as two influential parameters to tailor the buckling time between 1 and 4 min as confirmed by both experiments and simulation. The phenomenon reported here, chemically induced buckling via a combination of the SME and swelling, is generic, and the study reported here should be applicable to other water- and non-water-responsive gels.

  11. Historical temperature variability affects coral response to heat stress.

    Directory of Open Access Journals (Sweden)

    Jessica Carilli

    Full Text Available Coral bleaching is the breakdown of symbiosis between coral animal hosts and their dinoflagellate algae symbionts in response to environmental stress. On large spatial scales, heat stress is the most common factor causing bleaching, which is predicted to increase in frequency and severity as the climate warms. There is evidence that the temperature threshold at which bleaching occurs varies with local environmental conditions and background climate conditions. We investigated the influence of past temperature variability on coral susceptibility to bleaching, using the natural gradient in peak temperature variability in the Gilbert Islands, Republic of Kiribati. The spatial pattern in skeletal growth rates and partial mortality scars found in massive Porites sp. across the central and northern islands suggests that corals subject to larger year-to-year fluctuations in maximum ocean temperature were more resistant to a 2004 warm-water event. In addition, a subsequent 2009 warm event had a disproportionately larger impact on those corals from the island with lower historical heat stress, as indicated by lower concentrations of triacylglycerol, a lipid utilized for energy, as well as thinner tissue in those corals. This study indicates that coral reefs in locations with more frequent warm events may be more resilient to future warming, and protection measures may be more effective in these regions.

  12. Intraindividual response variability is malleable: Feedback- and education-related reductions in variability with age

    Directory of Open Access Journals (Sweden)

    Douglas D. Garrett

    2012-05-01

    Full Text Available Intraindividual variability (IIV in trial-to-trial reaction time is a robust and stable within-person marker of aging. However, it remains unknown whether IIV can be modulated experimentally. In a sample of healthy younger and older adults, we examined the effects of motivation- and performance-based feedback, age, and education level on IIV in a choice RT task (four blocks over 15 minutes. We found that IIV was reduced with block-by-block feedback, particularly for highly educated older adults. Notably, the baseline difference in IIV levels between this group and the young adults was reduced by 50%; by the final testing block, this advantaged older group had improved such that they were statistically indistinguishable from young adults on two of three preceding testing blocks. Our findings confirmed that response IIV is indeed modifiable, within mere minutes of feedback and testing.

  13. Avian community responses to variability in river hydrology.

    Science.gov (United States)

    Royan, Alexander; Hannah, David M; Reynolds, S James; Noble, David G; Sadler, Jonathan P

    2013-01-01

    River flow is a major driver of morphological structure and community dynamics in riverine-floodplain ecosystems. Flow influences in-stream communities through changes in water velocity, depth, temperature, turbidity and nutrient fluxes, and perturbations in the organisation of lower trophic levels are cascaded through the food web, resulting in shifts in food availability for consumer species. River birds are sensitive to spatial and phenological mismatches with aquatic prey following flow disturbances; however, the role of flow as a determinant of riparian ecological structure remains poorly known. This knowledge is crucial to help to predict if, and how, riparian communities will be influenced by climate-induced changes in river flow characterised by more extreme high (i.e. flood) and/or low (i.e. drought) flow events. Here, we combine national-scale datasets of river bird surveys and river flow archives to understand how hydrological disturbance has affected the distribution of riparian species at higher trophic levels. Data were analysed for 71 river locations using a Generalized Additive Model framework and a model averaging procedure. Species had complex but biologically interpretable associations with hydrological indices, with species' responses consistent with their ecology, indicating that hydrological-disturbance has implications for higher trophic levels in riparian food webs. Our quantitative analysis of river flow-bird relationships demonstrates the potential vulnerability of riparian species to the impacts of changing flow variability and represents an important contribution in helping to understand how bird communities might respond to a climate change-induced increase in the intensity of floods and droughts. Moreover, the success in relating parameters of river flow variability to species' distributions highlights the need to include river flow data in climate change impact models of species' distributions.

  14. Anaerobic biodegradability of macropollutants

    DEFF Research Database (Denmark)

    Angelidaki, Irini

    2002-01-01

    A variety of test procedures for determination of anaerobic biodegradability has been reported. This paper reviews the methods developed for determination of anaerobic biodegradability of macro-pollutants. Anaerobic biodegradability of micro-pollutants is not included. Furthermore, factors import...

  15. Sterilization-Induced Changes in Surface Topography of Biodegradable POSS-PCLU and the Cellular Response of Human Dermal Fibroblasts.

    Science.gov (United States)

    Yildirimer, Lara; Seifalian, Alexander M

    2015-06-01

    The field of tissue engineering is rapidly evolving, generating numerous biodegradable materials suited as regeneration platforms. Material sterility is of fundamental importance for clinical translation; however, a few studies have systematically researched the effects of different sterilization methods on biodegradable materials. Here, we exposed a novel bioabsorbable nanocomposite based on a poly(ɛ-caprolactone urea) urethane backbone integrating polyhedral oligomeric silsesquioxane nanoparticles (POSS-PCLU) to autoclave, microwave, antibiotics, and 70% ethanol sterilization and systematically correlated differences in material characteristics to the attachment, viability, proliferative capacity, and shape of human dermal fibroblasts (HDFa). Nanotopographical profiling of autoclaved or microwaved surfaces revealed relatively deep nano-grooves, increasing total surface area, roughness, and hydrophobicity, which resulted in significantly fewer adherent cells. Antibiotics or 70% ethanol-treated surfaces displayed shallower nano-grooves, a more hydrophilic character, and significantly greater cellular adhesion (ppostproduction processing tool to enhance cytocompatibility of tissue engineering scaffolds.

  16. Pavement Response to Variable Tyre Pressure of Heavy Vehicles

    Directory of Open Access Journals (Sweden)

    Arshad Ahmad Kamil

    2016-01-01

    Full Text Available In recent years, the effect of overinflated tyre pressure and increased heavy vehicles’ axle load on flexible pavements has become a subject of great concern because of the higher stress levels induced and damage caused to road pavements. This paper aims to evaluate the effect of variable tyre inflation pressures (using actual tyre contact/footprint area to determine the responses of flexible pavement. A full scale experiment was conducted on a heavy vehicle with 1:1:2 axle configuration, 10 R 20 tyre size and attached trailer with constant axle load. Measurements were made for actual tyre-pavement contact area. KENPAVE linear elastic program was then used to analyse the effects of the measured actual tyre-pavement contact area and the results was compared using conventional circular tyre contact area. A comparative analysis was then made between the actual contact area and the conventional circular tyre contact area. It was found that high tyre inflation pressure produce smaller contact area, giving more detrimental effect on the flexible pavement. It was also found that the temperature of tyres when the heavy vehicles are operational give less significant impact on tyre inflation pressure for the Malaysian climate.

  17. Global Response to Tropical Diabatic Heating Variability in Boreal Winter

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xu; Hai LIN; JIANG Jing

    2012-01-01

    Global teleconnections associated with tropical convective activities were investigated,based on monthly data of 29 Northern Hemisphere winters:December,January,February,and March (DJFM).First,EOF analyses were performed on the outgoing long-wave radiation (OLR) data to characterize the convective activity variability in the tropical Indian Ocean and the western Pacific.The first EOF mode of the convective activity was highly correlated with the ENSO.The second EOF mode had an east-west dipole structure,and the third EOF mode had three convective activity centers.Two distinct teleconnection patterns were identified that were associated,respectively,with the second and third EOF modes. A global primitive equation model was used to investigate the physical mechanism that causes the global circulation anomalies.The model responses to anomalous tropical thermal forcings that mimic the EOF patterns matched the general features of the observed circulation anomalies well,and they were mainly controlled by linear processes.The importance of convective activities in the tropical Indian Ocean and western Pacific to the extended- and long-range forecasting capability in the extratropics is discussed.

  18. Biodegradation and bioremediation

    DEFF Research Database (Denmark)

    Albrechtsen, H.-J.

    1996-01-01

    Anmeldelse af Alexander,M.: Biodegradation and bioremediation. Academic Press, Sandiego, USA, 1994......Anmeldelse af Alexander,M.: Biodegradation and bioremediation. Academic Press, Sandiego, USA, 1994...

  19. Biodegradation of Alachlor in Liquid and Soil Cultures Under Variable Carbon and Nitrogen Sources by Bacterial Consortium Isolated from Corn Field Soil

    Directory of Open Access Journals (Sweden)

    Simin Nasseri

    2013-03-01

    Full Text Available Alachlor, an aniline herbicide widely used in corn production, is frequently detected in water resources. The main objectives of this research were focused on isolating bacterial consortium capable of alachlor biodegradation, assessing the effects of carbon and nitrogen sources on alachlor biodegradation and evaluating the feasibility of using bacterial consortium in soil culture. Kavar corn field soil with a long history of alachlor application in Fars province of Iran has been explored for their potential of alachlor biodegradation. The influence of different carbon compounds (glucose, sodium citrate, sucrose, starch and the combination of these compounds, the effect of nitrogen sources (ammonium nitrate and urea and different pH (5.5-8.5 on alachlor removal efficiency by the bacterial consortium in liquid culture were investigated. After a multi-step enrichment program 100 days of acclimation, a culture with the high capability of alachlor degradation was obtained (63%. Glucose and sodium citrate had the highest alachlor reduction rate (85%. Alachlor reduction rate increased more rapidly by the addition of ammonium nitrate (94% compare to urea. Based on the data obtained in the present study, pH of 7.5 is optimal for alachlor biodegradation. After 30 days of incubation, the percent of alachlor reduction were significantly enhanced in the inoculated soils (74% as compared to uninoculated control soils (17.67% at the soil moisture content of 25%. In conclusion, bioaugmentation of soil with bacterial consortium may enhance the rate of alachlor degradation in a polluted soil.

  20. Injectable biocompatible and biodegradable pH-responsive hollow particle gels containing poly(acrylic acid): the effect of copolymer composition on gel properties.

    Science.gov (United States)

    Halacheva, Silvia S; Adlam, Daman J; Hendow, Eseelle K; Freemont, Tony J; Hoyland, Judith; Saunders, Brian R

    2014-05-12

    The potential of various pH-responsive alkyl (meth)acrylate ester- and (meth)acrylic acid-based copolymers, including poly(methyl methacrylate-co-acrylic acid) (PMMA-AA) and poly(n-butyl acrylate-co-methacrylic acid) (PBA-MAA), to form pH-sensitive biocompatible and biodegradable hollow particle gel scaffolds for use in non-load-bearing soft tissue regeneration have been explored. The optimal copolymer design criteria for preparation of these materials have been established. Physical gels which are both pH- and redox-sensitive were formed only from PMMA-AA copolymers. MMA is the optimal hydrophobic monomer, whereas the use of various COOH-containing monomers, e.g., MAA and AA, will always induce a pH-triggered physical gelation. The PMMA-AA gels were prepared at physiological pH range from concentrated dispersions of swollen, hollow, polymer-based particles cross-linked with either cystamine (CYS) or 3,3'-dithiodipropionic acid dihydrazide (DTP). A linear relationship between particle swelling ratios, gel elasticity, and ductility was observed. The PMMA-AA gels with lower AA contents feature lower swelling ratios, mechanical strengths, and ductilities. Increasing the swelling ratio (e.g., through increasing AA content) decreased the intraparticle elasticity; however, intershell contact and gel elasticity were found to increase. The mechanical properties and performance of the gels were tuneable upon varying the copolymers' compositions and the structure of the cross-linker. Compared to PMMA-AA/CYS, the PMMA-AA/DTP gels were more elastic and ductile. The biodegradability and cytotoxicity of the new hollow particle gels were tested for the first time and related to their composition, mechanical properties, and morphology. The new PMMA-AA/CYS and PMMA-AA/DTP gels have shown good biocompatibility, biodegradability, strength, and interconnected porosity and therefore have good potential as a tissue repair agent.

  1. Long-term sustained release of salicylic acid from cross-linked biodegradable polyester induces a reduced foreign body response in mice.

    Science.gov (United States)

    Chandorkar, Yashoda; Bhaskar, Nitu; Madras, Giridhar; Basu, Bikramjit

    2015-02-09

    There has been a continuous surge toward developing new biopolymers that exhibit better in vivo biocompatibility properties in terms of demonstrating a reduced foreign body response (FBR). One approach to mitigate the undesired FBR is to develop an implant capable of releasing anti-inflammatory molecules in a sustained manner over a long time period. Implants causing inflammation are also more susceptible to infection. In this article, the in vivo biocompatibility of a novel, biodegradable salicylic acid releasing polyester (SAP) has been investigated by subcutaneous implantation in a mouse model. The tissue response to SAP was compared with that of a widely used biodegradable polymer, poly(lactic acid-co-glycolic acid) (PLGA), as a control over three time points: 2, 4, and 16 weeks postimplantation. A long-term in vitro study illustrates a continuous, linear (zero order) release of salicylic acid with a cumulative mass percent release rate of 7.34 × 10(-4) h(-1) over ∼1.5-17 months. On the basis of physicochemical analysis, surface erosion for SAP and bulk erosion for PLGA have been confirmed as their dominant degradation modes in vivo. On the basis of the histomorphometrical analysis of inflammatory cell densities and collagen distribution as well as quantification of proinflammatory cytokine levels (TNF-α and IL-1β), a reduced foreign body response toward SAP with respect to that generated by PLGA has been unambiguously established. The favorable in vivo tissue response to SAP, as manifest from the uniform and well-vascularized encapsulation around the implant, is consistent with the decrease in inflammatory cell density and increase in angiogenesis with time. The above observations, together with the demonstration of long-term and sustained release of salicylic acid, establish the potential use of SAP for applications in improved matrices for tissue engineering and chronic wound healing.

  2. Response variability in rapid automatized naming predicts reading comprehension

    OpenAIRE

    Li, James J.; Cutting, Laurie E.; Ryan, Matthew; Zilioli, Monica; DENCKLA, MARTHA B.; MAHONE, E. MARK

    2009-01-01

    A total of 37 children ages 8 to 14 years, screened for word-reading difficulties (23 with attention-deficit/hyperactivity disorder, ADHD; 14 controls) completed oral reading and rapid automatized naming (RAN) tests. RAN trials were segmented into pause and articulation time and intraindividual variability. There were no group differences on reading or RAN variables. Color- and letter-naming pause times and number-naming articulation time were significant predictors of reading fluency. In con...

  3. Cropping frequency and area response to climate variability can exceed yield response

    Science.gov (United States)

    Cohn, Avery S.; Vanwey, Leah K.; Spera, Stephanie A.; Mustard, John F.

    2016-06-01

    The sensitivity of agricultural output to climate change has often been estimated by modelling crop yields under climate change scenarios or with statistical analysis of the impacts of year-to-year climatic variability on crop yields. However, the area of cropland and the number of crops harvested per growing season (cropping frequency) both also affect agricultural output and both also show sensitivity to climate variability and change. We model the change in agricultural output associated with the response of crop yield, crop frequency and crop area to year-to-year climate variability in Mato Grosso (MT), Brazil, a key agricultural region. Roughly 70% of the change in agricultural output caused by climate was determined by changes in frequency and/or changes in area. Hot and wet conditions were associated with the largest losses and cool and dry conditions with the largest gains. All frequency and area effects had the same sign as total effects, but this was not always the case for yield effects. A focus on yields alone may therefore bias assessments of the vulnerability of agriculture to climate change. Efforts to reduce climate impacts to agriculture should seek to limit production losses not only from crop yield, but also from changes in cropland area and cropping frequency.

  4. Bayesian modeling of measurement error in predictor variables using item response theory

    NARCIS (Netherlands)

    Fox, Jean-Paul; Glas, Cees A.W.

    2003-01-01

    It is shown that measurement error in predictor variables can be modeled using item response theory (IRT). The predictor variables, that may be defined at any level of an hierarchical regression model, are treated as latent variables. The normal ogive model is used to describe the relation between t

  5. Biodegradation of C.I. Acid Blue 92 by Nasturtium officinale: Study of Some Physiological Responses and Metabolic Fate of Dye.

    Science.gov (United States)

    Torbati, S; Movafeghi, A; Khataee, A R

    2015-01-01

    The present study was conducted to evaluate the potential of aquatic vascular plant, Nasturtium officinale, for degradation of C.I. Acid Blue 92 (AB92). The effect of operational parameters such as initial dye concentration, plant biomass, pH, and temperature on the efficiency of biological decolorization process was determined. The reusability of the plant in long term repetitive operations confirmed the biological degradation process. The by-products formed during biodegradation process were identified by GC-MS technique. The effects of the dye on several plant physiological responses such as photosynthetic pigments content and antioxidant enzymes activity were investigated. The content of chlorophyll and carotenoids was significantly reduced at 20 mg/L of the dye. The activities of superoxide dismutase and peroxidase were remarkably increased in the plant root verifying their importance in plant tolerance to the dye contamination.

  6. Increasing Response Variability of Mand Frames with Script Training and Extinction

    Science.gov (United States)

    Betz, Alison M.; Higbee, Thomas S.; Kelley, Kristen N.; Sellers, Tyra P.; Pollard, Joy S.

    2011-01-01

    Children with autism often demonstrate less variable behavior than their typically developing peers and those with other cognitive disabilities. A possible reason for lack of response variability emitted by children with autism is that they do not have a variety of response forms in their repertoire. Multiple-exemplar training through the use of…

  7. Prediction of anaerobic biodegradability and bioaccessibility of municipal sludge by coupling sequential extractions with fluorescence spectroscopy: towards ADM1 variables characterization.

    Science.gov (United States)

    Jimenez, Julie; Gonidec, Estelle; Cacho Rivero, Jesús Andrés; Latrille, Eric; Vedrenne, Fabien; Steyer, Jean-Philippe

    2014-03-01

    Advanced dynamic anaerobic digestion models, such as ADM1, require both detailed organic matter characterisation and intimate knowledge of the involved metabolic pathways. In the current study, a methodology for municipal sludge characterization is investigated to describe two key parameters: biodegradability and bioaccessibility of organic matter. The methodology is based on coupling sequential chemical extractions with 3D fluorescence spectroscopy. The use of increasingly strong solvents reveals different levels of organic matter accessibility and the spectroscopy measurement leads to a detailed characterisation of the organic matter. The results obtained from testing 52 municipal sludge samples (primary, secondary, digested and thermally treated) showed a successful correlation with sludge biodegradability and bioaccessibility. The two parameters, traditionally obtained through the biochemical methane potential (BMP) lab tests, are now obtain in only 5 days compared to the 30-60 days usually required. Experimental data, obtained from two different laboratory scale reactors, were used to validate the ADM1 model. The proposed approach showed a strong application potential for reactor design and advanced control of anaerobic digestion processes.

  8. Biodegradable synthetic bone composites

    Science.gov (United States)

    Liu, Gao; Zhao, Dacheng; Saiz, Eduardo; Tomsia, Antoni P.

    2013-01-01

    The invention provides for a biodegradable synthetic bone composition comprising a biodegradable hydrogel polymer scaffold comprising a plurality of hydrolytically unstable linkages, and an inorganic component; such as a biodegradable poly(hydroxyethylmethacrylate)/hydroxyapatite (pHEMA/HA) hydrogel composite possessing mineral content approximately that of human bone.

  9. Glacier response to North Atlantic climate variability during the Holocene

    Directory of Open Access Journals (Sweden)

    N. L. Balascio

    2015-05-01

    Full Text Available Small glaciers and ice caps respond rapidly to climate variations and records of their past extent provide information on the natural envelope of past climate variability. Millennial-scale trends in Holocene glacier size are well documented and correspond with changes in Northern Hemisphere summer insolation. However, there is only sparse and fragmentary evidence for higher frequency variations in glacier size because in many Northern Hemisphere regions glacier advances of the past few hundred years were the most extensive and destroyed the geomorphic evidence of ice growth and retreat during the past several thousand years. Thus, most glacier records have been of limited use for investigating centennial scale climate forcing and feedback mechanisms. Here we report a continuous record of glacier activity for the last 9.5 ka from southeast Greenland, derived from high-resolution measurements on a proglacial lake sediment sequence. Physical and geochemical parameters show that the glaciers responded to previously documented Northern Hemisphere climatic excursions, including the "8.2 ka" cooling event, the Holocene Thermal Maximum, Neoglacial cooling, and 20th Century warming. In addition, the sediments indicate centennial-scale oscillations in glacier size during the late Holocene. Beginning at 4.1 ka, a series of abrupt glacier advances occurred, each lasting ~100 years and followed by a period of retreat, that were superimposed on a gradual trend toward larger glacier size. Thus, while declining summer insolation caused long-term cooling and glacier expansions during the late Holocene, climate system dynamics resulted in repeated episodes of glacier expansion and retreat on multi-decadal to centennial timescales. These episodes coincided with ice rafting events in the North Atlantic Ocean and periods of regional ice cap expansion, which confirms their regional significance and indicates that considerable glacier activity on these timescales is a

  10. Nanostructure controlled sustained delivery of human growth hormone using injectable, biodegradable, pH/temperature responsive nanobiohybrid hydrogel

    Science.gov (United States)

    Singh, Narendra K.; Nguyen, Quang Vinh; Kim, Bong Sup; Lee, Doo Sung

    2015-02-01

    The clinical efficacy of a therapeutic protein, the human growth hormone (hGH), is limited by its short plasma half-life and premature degradation. To overcome this limitation, we proposed a new protein delivery system by the self-assembly and intercalation of a negatively charged hGH onto a positively charged 2D-layered double hydroxide nanoparticle (LDH). The LDH-hGH ionic complex, with an average particle size of approximately 100 nm, retards hGH diffusion. Nanobiohybrid hydrogels (PAEU/LDH-hGH) were prepared by dispersing the LDH-hGH complex into a cationic pH- and temperature-sensitive injectable PAEU copolymer hydrogel to enhance sustained hGH release by dual ionic interactions. Biodegradable copolymer hydrogels comprising poly(β-amino ester urethane) and triblock poly(ε-caprolactone-lactide)-poly(ethylene glycol)-poly-(ε-caprolactone-lactide) (PCLA-PEG-PCLA) were synthesized and characterized. hGH was self-assembled and intercalated onto layered LDH nanoparticles through an anion exchange technique. X-ray diffraction and zeta potential results showed that the LDH-hGH complex was prepared successfully and that the PAEU/LDH-hGH nanobiohybrid hydrogel had a disordered intercalated nanostructure. The biocompatibility of the nanobiohybrid hydrogel was confirmed by an in vitro cytotoxicity test. The in vivo degradation of pure PAEU and its nanobiohybrid hydrogels was investigated and it showed a controlled degradation of the PAEU/LDH nanobiohybrids compared with the pristine PAEU copolymer hydrogel. The LDH-hGH loaded injectable hydrogels suppressed the initial burst release of hGH and extended the release period for 13 days in vitro and 5 days in vivo. The developed nanohybrid hydrogel has the potential for application as a protein carrier to improve patient compliance.The clinical efficacy of a therapeutic protein, the human growth hormone (hGH), is limited by its short plasma half-life and premature degradation. To overcome this limitation, we proposed a new

  11. Microbial community evolution during simulated managed aquifer recharge in response to different biodegradable dissolved organic carbon (BDOC) concentrations

    KAUST Repository

    Li, Dong

    2013-05-01

    This study investigates the evolution of the microbial community in laboratory-scale soil columns simulating the infiltration zone of managed aquifer recharge (MAR) systems and analogous natural aquifer sediment ecosystems. Parallel systems were supplemented with either moderate (1.1 mg/L) or low (0.5 mg/L) biodegradable dissolved organic carbon (BDOC) for a period of six months during which time, spatial (1 cm, 30 cm, 60 cm, 90 cm, and 120 cm) and temporal (monthly) analyses of sediment-associated microbial community structure were analyzed. Total microbial biomass associated with sediments was positively correlated with BDOC concentration where a significant decline in BDOC was observed along the column length. Analysis of 16S rRNA genes indicated dominance by Bacteria with Archaea comprising less than 1 percent of the total community. Proteobacteria was found to be the major phylum in samples from all column depths with contributions from Betaproteobacteria, Alphaproteobacteria and Gammaproteobacteria. Microbial community structure at all the phylum, class and genus levels differed significantly at 1 cm between columns receiving moderate and low BDOC concentrations; in contrast strong similarities were observed both between parallel column systems and across samples from 30 to 120 cm depths. Samples from 1 cm depth of the low BDOC columns exhibited higher microbial diversity (expressed as Shannon Index) than those at 1 cm of moderate BDOC columns, and both increased from 5.4 to 5.9 at 1 cm depth to 6.7-8.3 at 30-120 cm depths. The microbial community structure reached steady state after 3-4 months since the initiation of the experiment, which also resulted in an improved DOC removal during the same time period. This study suggested that BDOC could significantly influence microbial community structure regarding both composition and diversity of artificial MAR systems and analogous natural aquifer sediment ecosystems. © 2013 Elsevier Ltd.

  12. RELATION BETWEEN BACKGROUND VARIABLES, VALUES AND CORPORATE SOCIAL RESPONSIBILITY

    Directory of Open Access Journals (Sweden)

    Maria del Rosario González-Rodriguez

    2016-02-01

    Full Text Available Consumer perception of corporate social responsibility (CSR can be directly influenced by individual value structures. This research aims to provide new knowledge regarding the relationship between basic human values and the public’s perception of CSR. It focuses on the values of higher education students and their views regarding a particular corporate social initiative. The study reveals that social, educational, and economic circumstances influence human values. Those values in turn influence why different students perceive CSR differently. These findings are relevant to companies as they provide a more detailed understanding of why certain consumer groups perceive certain CSR initiatives the way that they do. They also suggest that universities should increase their awareness of the importance of integrating human values and CSR in the curricula of future business managers and social leaders.

  13. A plant's perspective of extremes: terrestrial plant responses to changing climatic variability.

    Science.gov (United States)

    Reyer, Christopher P O; Leuzinger, Sebastian; Rammig, Anja; Wolf, Annett; Bartholomeus, Ruud P; Bonfante, Antonello; de Lorenzi, Francesca; Dury, Marie; Gloning, Philipp; Abou Jaoudé, Renée; Klein, Tamir; Kuster, Thomas M; Martins, Monica; Niedrist, Georg; Riccardi, Maria; Wohlfahrt, Georg; de Angelis, Paolo; de Dato, Giovanbattista; François, Louis; Menzel, Annette; Pereira, Marízia

    2013-01-01

    We review observational, experimental, and model results on how plants respond to extreme climatic conditions induced by changing climatic variability. Distinguishing between impacts of changing mean climatic conditions and changing climatic variability on terrestrial ecosystems is generally underrated in current studies. The goals of our review are thus (1) to identify plant processes that are vulnerable to changes in the variability of climatic variables rather than to changes in their mean, and (2) to depict/evaluate available study designs to quantify responses of plants to changing climatic variability. We find that phenology is largely affected by changing mean climate but also that impacts of climatic variability are much less studied, although potentially damaging. We note that plant water relations seem to be very vulnerable to extremes driven by changes in temperature and precipitation and that heat-waves and flooding have stronger impacts on physiological processes than changing mean climate. Moreover, interacting phenological and physiological processes are likely to further complicate plant responses to changing climatic variability. Phenological and physiological processes and their interactions culminate in even more sophisticated responses to changing mean climate and climatic variability at the species and community level. Generally, observational studies are well suited to study plant responses to changing mean climate, but less suitable to gain a mechanistic understanding of plant responses to climatic variability. Experiments seem best suited to simulate extreme events. In models, temporal resolution and model structure are crucial to capture plant responses to changing climatic variability. We highlight that a combination of experimental, observational, and/or modeling studies have the potential to overcome important caveats of the respective individual approaches.

  14. Capturing the dynamics of response variability in the brain in ADHD

    Directory of Open Access Journals (Sweden)

    Janna van Belle

    2015-01-01

    Full Text Available ADHD is characterized by increased intra-individual variability in response times during the performance of cognitive tasks. However, little is known about developmental changes in intra-individual variability, and how these changes relate to cognitive performance. Twenty subjects with ADHD aged 7–24 years and 20 age-matched, typically developing controls participated in an fMRI-scan while they performed a go-no-go task. We fit an ex-Gaussian distribution on the response distribution to objectively separate extremely slow responses, related to lapses of attention, from variability on fast responses. We assessed developmental changes in these intra-individual variability measures, and investigated their relation to no-go performance. Results show that the ex-Gaussian measures were better predictors of no-go performance than traditional measures of reaction time. Furthermore, we found between-group differences in the change in ex-Gaussian parameters with age, and their relation to task performance: subjects with ADHD showed age-related decreases in their variability on fast responses (sigma, but not in lapses of attention (tau, whereas control subjects showed a decrease in both measures of variability. For control subjects, but not subjects with ADHD, this age-related reduction in variability was predictive of task performance. This group difference was reflected in neural activation: for typically developing subjects, the age-related decrease in intra-individual variability on fast responses (sigma predicted activity in the dorsal anterior cingulate gyrus (dACG, whereas for subjects with ADHD, activity in this region was related to improved no-go performance with age, but not to intra-individual variability. These data show that using more sophisticated measures of intra-individual variability allows the capturing of the dynamics of task performance and associated neural changes not permitted by more traditional measures.

  15. Variable Selection for Varying-Coefficient Models with Missing Response at Random

    Institute of Scientific and Technical Information of China (English)

    Pei Xin ZHAO; Liu Gen XUE

    2011-01-01

    In this paper, we present a variable selection procedure by combining basis function approximations with penalized estimating equations for varying-coefficient models with missing response at random. With appropriate selection of the tuning parameters, we establish the consistency of the variable selection procedure and the optimal convergence rate of the regularized estimators. A simulation study is undertaken to assess the finite sample performance of the proposed variable selection procedure.

  16. A latent class distance association model for cross-classified data with a categorical response variable

    NARCIS (Netherlands)

    Vera, J.F.; Rooij, M. de; Heiser, W.J.

    2014-01-01

    In this paper we propose a latent class distance association model for clustering in the predictor space of large contingency tables with a categorical response variable. The rows of such a table are characterized as profiles of a set of explanatory variables, while the columns represent a single ou

  17. A Composite Likelihood Inference in Latent Variable Models for Ordinal Longitudinal Responses

    Science.gov (United States)

    Vasdekis, Vassilis G. S.; Cagnone, Silvia; Moustaki, Irini

    2012-01-01

    The paper proposes a composite likelihood estimation approach that uses bivariate instead of multivariate marginal probabilities for ordinal longitudinal responses using a latent variable model. The model considers time-dependent latent variables and item-specific random effects to be accountable for the interdependencies of the multivariate…

  18. [Biodegradation of polyethylene].

    Science.gov (United States)

    Yang, Jun; Song, Yi-ling; Qin, Xiao-yan

    2007-05-01

    Plastic material is one of the most serious solid wastes pollution. More than 40 million tons of plastics produced each year are discarded into environment. Plastics accumulated in the environment is highly resistant to biodegradation and not be able to take part in substance recycle. To increase the biodegradation efficiency of plastics by different means is the main research direction. This article reviewed the recent research works of polyethylene biodegradation that included the modification and pretreatment of polyethylene, biodegradation pathway, the relevant microbes and enzymes and the changes of physical, chemical and biological properties after biodegradation. The study directions of exploiting the kinds of life-forms of biodegradation polyethylene except the microorganisms, isolating and cloning the key enzymes and gene that could produce active groups, and enhancing the study on polyethylene biodegradation without additive were proposed.

  19. Plant response to nutrient availability across variable bedrock geologies

    Science.gov (United States)

    Castle, S.C.; Neff, J.C.

    2009-01-01

    We investigated the role of rock-derived mineral nutrient availability on the nutrient dynamics of overlying forest communities (Populus tremuloides and Picea engelmanni-Abies lasiocarpa v. arizonica) across three parent materials (andesite, limestone, and sandstone) in the southern Rocky Mountains of Colorado. Broad geochemical differences were observed between bedrock materials; however, bulk soil chemistries were remarkably similar between the three different sites. In contrast, soil nutrient pools were considerably different, particularly for P, Ca, and Mg concentrations. Despite variations in nutrient stocks and nutrient availability in soils, we observed relatively inflexible foliar concentrations and foliar stoichiometries for both deciduous and coniferous species. Foliar nutrient resorption (P and K) in the deciduous species followed patterns of nutrient content across substrate types, with higher resorption corresponding to lower bedrock concentrations. Work presented here indicates a complex plant response to available soil nutrients, wherein plant nutrient use compensates for variations in supply gradients and results in the maintenance of a narrow range in foliar stoichiometry. ?? 2008 Springer Science+Business Media, LLC.

  20. Phyllosphere yeasts rapidly break down biodegradable plastics.

    Science.gov (United States)

    Kitamoto, Hiroko K; Shinozaki, Yukiko; Cao, Xiao-Hong; Morita, Tomotake; Konishi, Masaaki; Tago, Kanako; Kajiwara, Hideyuki; Koitabashi, Motoo; Yoshida, Shigenobu; Watanabe, Takashi; Sameshima-Yamashita, Yuka; Nakajima-Kambe, Toshiaki; Tsushima, Seiya

    2011-11-29

    The use of biodegradable plastics can reduce the accumulation of environmentally persistent plastic wastes. The rate of degradation of biodegradable plastics depends on environmental conditions and is highly variable. Techniques for achieving more consistent degradation are needed. However, only a few microorganisms involved in the degradation process have been isolated so far from the environment. Here, we show that Pseudozyma spp. yeasts, which are common in the phyllosphere and are easily isolated from plant surfaces, displayed strong degradation activity on films made from poly-butylene succinate or poly-butylene succinate-co-adipate. Strains of P. antarctica isolated from leaves and husks of paddy rice displayed strong degradation activity on these films at 30°C. The type strain, P. antarctica JCM 10317, and Pseudozyma spp. strains from phyllosphere secreted a biodegradable plastic-degrading enzyme with a molecular mass of about 22 kDa. Reliable source of biodegradable plastic-degrading microorganisms are now in our hands.

  1. Application of response surface methodology for rapid chrysene biodegradation by newly isolated marine-derived fungus Cochliobolus lunatus strain CHR4D.

    Science.gov (United States)

    Bhatt, Jwalant K; Ghevariya, Chirag M; Dudhagara, Dushyant R; Rajpara, Rahul K; Dave, Bharti P

    2014-11-01

    For the first time, Cochliobolus lunatus strain CHR4D, a marine-derived ascomycete fungus isolated from historically contaminated crude oil polluted shoreline of Alang-Sosiya ship-breaking yard, at Bhavnagar coast, Gujarat has been reported showing the rapid and enhanced biodegradation of chrysene, a four ringed high molecular weight (HMW) polycyclic aromatic hydrocarbon (PAH). Mineral Salt Broth (MSB) components such as ammonium tartrate and glucose along with chrysene, pH and trace metal solution have been successfully optimized by Response Surface Methodology (RSM) using central composite design (CCD). A validated, two-step optimization protocol has yielded a substantial 93.10% chrysene degradation on the 4(th) day, against unoptimized 56.37% degradation on the 14(th) day. The results depict 1.65 fold increase in chrysene degradation and 1.40 fold increase in biomass with a considerable decrement in time. Based on the successful laboratory experiments, C. lunatus strain CHR4D can thus be predicted as a potential candidate for mycoremediation of HMW PAHs impacted environments.

  2. Biodegradation of butachlor by Rhodococcus sp. strain B1 and purification of its hydrolase (ChlH) responsible for N-dealkylation of chloroacetamide herbicides.

    Science.gov (United States)

    Liu, Hong-Ming; Cao, Li; Lu, Peng; Ni, Haiyan; Li, Yun-Xiang; Yan, Xin; Hong, Qing; Li, Shun-Peng

    2012-12-19

    Rhodococcus sp. strain B1 could degrade 100 mg/L butachlor within 5 days. Butachlor was first hydrolyzed by strain B1 through N-dealkylation, which resulted in the production of butoxymethanol and 2-chloro-N-(2,6-dimethylphenyl)acetamide. Butoxymethanol could be further degraded and utilized as the carbon source for the growth of strain B1, whereas 2-chloro-N-(2,6-dimethylphenyl)acetamide could not be degraded further. The hydrolase designated ChlH, responsible for the N-dealkylation of the side chain of butachlor, was purified 185.1-fold to homogeneity with 16.1% recovery. The optimal pH and temperature of ChlH were observed to be 7.0-7.5 and 30 °C, respectively. This enzyme was also able to catalyze the N-dealkylation of other chloroacetamide herbicides; the catalytic efficiency followed the order alachlor > acetochlor >butachlor > pretilachlor, which indicated that the alkyl chain length influenced the N-dealkylation of the chloroacetamide herbicides. This is the first report on the biodegradation of chloroacetamide herbicides at the enzyme level.

  3. Influence of soil contamination with PAH on microbial community dynamics and expression level of genes responsible for biodegradation of PAH and production of rhamnolipids

    OpenAIRE

    Szczepaniak, Zuzanna; Czarny, Jakub; Staninska-Pięta, Justyna; Lisiecki, Piotr; Zgoła-Grześkowiak, Agnieszka; Cyplik, Paweł; Chrzanowski, Łukasz; Wolko, Łukasz; Marecik, Roman; Juzwa, Wojciech; Glazar, Katarzyna; Piotrowska-Cyplik, Agnieszka

    2016-01-01

    The aim of this study was to evaluate the effect of bioaugmentation and addition of rhamnolipids on the biodegradation of PAHs in artificially contaminated soil, expression of genes crucial for the biodegradation process (PAHRHDαGN, PAHRHDαGP), and the synthesis of rhamnolipids as well as population changes in the soil bacterial metabiome. The positive effect of bioaugmentation and addition of rhamnolipids on the bioremediation of the majority of PAHs was confirmed during the early stages of ...

  4. Biodegradation of variable-chain-length n-alkanes in Rhodococcus opacus R7 and the involvement of an alkane hydroxylase system in the metabolism.

    Science.gov (United States)

    Zampolli, Jessica; Collina, Elena; Lasagni, Marina; Di Gennaro, Patrizia

    2014-01-01

    Rhodococcus opacus R7 is a Gram-positive bacterium isolated from a polycyclic aromatic hydrocarbon contaminated soil for its versatile metabolism; indeed the strain is able to grow on naphthalene, o-xylene, and several long- and medium-chain n-alkanes. In this work we determined the degradation of n-alkanes in Rhodococcus opacus R7 in presence of n-dodecane (C12), n-hexadecane (C16), n-eicosane (C20), n-tetracosane (C24) and the metabolic pathway in presence of C12. The consumption rate of C12 was 88%, of C16 was 69%, of C20 was 51% and of C24 it was 78%. The decrement of the degradation rate seems to be correlated to the length of the aliphatic chain of these hydrocarbons. On the basis of the metabolic intermediates determined by the R7 growth on C12, our data indicated that R. opacus R7 metabolizes medium-chain n-alkanes by the primary alcohol formation. This represents a difference in comparison with other Rhodococcus strains, in which a mixture of the two alcohols was observed. By GC-MSD analysis we also identified the monocarboxylic acid, confirming the terminal oxidation. Moreover, the alkB gene cluster from R. opacus R7 was isolated and its involvement in the n-alkane degradation system was investigated by the cloning of this genomic region into a shuttle-vector E. coli-Rhodococcus to evaluate the alkane hydroxylase activity. Our results showed an increased biodegradation of C12 in the recombinant strain R. erythropolis AP (pTipQT1-alkR7) in comparison with the wild type strain R. erythropolis AP. These data supported the involvement of the alkB gene cluster in the n-alkane degradation in the R7 strain.

  5. Stimuli-responsive protamine-based biodegradable nanocapsules for enhanced bioavailability and intracellular delivery of anticancer agents

    Energy Technology Data Exchange (ETDEWEB)

    Radhakrishnan, Krishna; Thomas, Midhun B.; Pulakkat, Sreeranjini [Indian Institute of Science, Department of Materials Engineering (India); Gnanadhas, Divya P.; Chakravortty, Dipshikha [Indian Institute of Science, Department of Microbiology and Cell Biology (India); Raichur, Ashok M., E-mail: amr@materials.iisc.ernet.in [Indian Institute of Science, Department of Materials Engineering (India)

    2015-08-15

    Enzyme- and pH-responsive polyelectrolyte nanocapsules having diameters in the range of 200 ± 20 nm were fabricated by means of Layer-by-Layer assembly of biopolymers, protamine, and heparin, and then loaded with anticancer drug doxorubicin. The incorporation of the FDA-approved peptide drug protamine as a wall component rendered the capsules responsive to enzyme stimuli. The stimuli-responsive drug release from these nanocapsules was evaluated, and further modulation of capsule permeability to avoid premature release was demonstrated by crosslinking the wall components. The interaction of the nanocapsules with cancer cells was studied using MCF-7 breast cancer cells. These capsules were readily internalized and disintegrated inside the cells, culminating in the release of the loaded doxorubicin and subsequent cell death as observed by confocal microscopy and MTT Assay. The bioavailability studies performed using BALB/c mice revealed that the encapsulated doxorubicin exhibited enhanced bioavailability compared to free doxorubicin. Our results indicate that this stimuli-responsive system fabricated from clinically used FDA-approved molecules and exhibiting minimal premature release has great potential for drug-delivery applications.

  6. Induction of potent CD8+ T-cell responses by novel biodegradable nanoparticles carrying human immunodeficiency virus type 1 gp120.

    Science.gov (United States)

    Wang, Xin; Uto, Tomofumi; Akagi, Takami; Akashi, Mitsuru; Baba, Masanori

    2007-09-01

    The mainstream of recent anti-AIDS vaccines is a prime/boost approach with multiple doses of the target DNA of human immunodeficiency virus type 1 (HIV-1) and recombinant viral vectors. In this study, we have attempted to construct an efficient protein-based vaccine using biodegradable poly(gamma-glutamic acid) (gamma-PGA) nanoparticles (NPs), which are capable of inducing potent cellular immunity. A significant expansion of CD8+ T cells specific to the major histocompatibility complex class I-restricted gp120 epitope was observed in mice intranasally immunized once with gp120-carrying NPs but not with gp120 alone or gp120 together with the B-subunit of cholera toxin. Both the gp120-encapsulating and -immobilizing forms of NPs could induce antigen-specific spleen CD8+ T cells having a functional profile of cytotoxic T lymphocytes. Long-lived memory CD8+ T cells could also be elicited. Although a substantial decay in the effector memory T cells was observed over time in the immunized mice, the central memory T cells remained relatively constant from day 30 to day 238 after immunization. Furthermore, the memory CD8+ T cells rapidly expanded with boosting with the same immunogen. In addition, gamma-PGA NPs were found to be a much stronger inducer of antigen-specific CD8+ T-cell responses than nonbiodegradable polystyrene NPs. Thus, gamma-PGA NPs carrying various HIV-1 antigens may have great potential as a novel priming and/or boosting tool in current vaccination regimens for the induction of cellular immune responses.

  7. Biodegradability of plastics.

    Science.gov (United States)

    Tokiwa, Yutaka; Calabia, Buenaventurada P; Ugwu, Charles U; Aiba, Seiichi

    2009-08-26

    Plastic is a broad name given to different polymers with high molecular weight, which can be degraded by various processes. However, considering their abundance in the environment and their specificity in attacking plastics, biodegradation of plastics by microorganisms and enzymes seems to be the most effective process. When plastics are used as substrates for microorganisms, evaluation of their biodegradability should not only be based on their chemical structure, but also on their physical properties (melting point, glass transition temperature, crystallinity, storage modulus etc.). In this review, microbial and enzymatic biodegradation of plastics and some factors that affect their biodegradability are discussed.

  8. A latent class distance association model for cross-classified data with a categorical response variable.

    Science.gov (United States)

    Vera, José Fernando; de Rooij, Mark; Heiser, Willem J

    2014-11-01

    In this paper we propose a latent class distance association model for clustering in the predictor space of large contingency tables with a categorical response variable. The rows of such a table are characterized as profiles of a set of explanatory variables, while the columns represent a single outcome variable. In many cases such tables are sparse, with many zero entries, which makes traditional models problematic. By clustering the row profiles into a few specific classes and representing these together with the categories of the response variable in a low-dimensional Euclidean space using a distance association model, a parsimonious prediction model can be obtained. A generalized EM algorithm is proposed to estimate the model parameters and the adjusted Bayesian information criterion statistic is employed to test the number of mixture components and the dimensionality of the representation. An empirical example highlighting the advantages of the new approach and comparing it with traditional approaches is presented.

  9. Heart rate variability response to mental arithmetic stress in patients with schizophrenia Autonomic response to stress in schizophrenia

    NARCIS (Netherlands)

    Castro, Mariana N.; Vigo, Daniel E.; Weidema, Hylke; Fahrer, Rodolfo D.; Chu, Elvina M.; De Achaval, Delfina; Nogues, Martin; Leiguarda, Ramon C.; Cardinali, Daniel P.; Guinjoan, Salvador N.

    2008-01-01

    Background: The vulnerability-stress hypothesis is an established model of schizophrenia symptom formation. We sought to characterise the pattern of the cardiac autonomic response to mental arithmetic stress in patients with stable schizophrenia. Methods: We performed heart rate variability (HRV) an

  10. Interplay between the acute inflammatory response and heart rate variability in healthy human volunteers.

    Science.gov (United States)

    Kox, Matthijs; Ramakers, Bart P; Pompe, Jan C; van der Hoeven, Johannes G; Hoedemaekers, Cornelia W; Pickkers, Peter

    2011-08-01

    The autonomic nervous system and the inflammatory response are intimately linked. Heart rate variability (HRV) analysis is a widely used method to assess cardiac autonomic nervous system activity, and changes in HRV indices may correlate with inflammatory markers. Here, we investigated whether baseline HRV predicts the acute inflammatory response to endotoxin. Second, we investigated whether the magnitude of the inflammatory response correlated with HRV alterations. Forty healthy volunteers received a single intravenous bolus of 2 ng/kg endotoxin (LPS, derived from Escherichia coli O:113). Of these, 12 healthy volunteers were administered LPS again 2 weeks later. Heart rate variability was determined at baseline (just before LPS administration) and hourly thereafter until 8 h after LPS administration. Plasma cytokine levels were determined at various time points. Baseline HRV indices did not correlate with the magnitude of the LPS-induced inflammatory response. Despite large alterations in HRV after LPS administration, the extent of the inflammatory response did not correlate with the magnitude of HRV changes. In subjects who were administered LPS twice, inflammatory cytokines were markedly attenuated after the second LPS administration, whereas LPS-induced HRV alterations were similar. Heart rate variability indices do not predict the acute inflammatory response in a standardized model of systemic inflammation. Although the acute inflammatory response results in HRV changes, no correlations with inflammatory cytokines were observed. Therefore, the magnitude of endotoxemia-related HRV changes does not reflect the extent of the inflammatory response.

  11. Atmospheric response to the North Pacific enabled by daily sea surface temperature variability

    Science.gov (United States)

    Zhou, Guidi; Latif, Mojib; Greatbatch, Richard J.; Park, Wonsun

    2015-09-01

    Ocean-atmosphere interactions play a key role in climate variability on a wide range of timescales from seasonal to decadal and longer. The extratropical oceans are thought to exert noticeable feedbacks on the atmosphere especially on decadal and longer timescales, yet the large-scale atmospheric response to anomalous extratropical sea surface temperature (SST) is still under debate. Here we show, by means of dedicated high-resolution atmospheric model experiments, that sufficient daily variability in the extratropical background SST needs to be resolved to force a statistically significant large-scale atmospheric response to decadal North Pacific SST anomalies associated with the Pacific Decadal Oscillation, which is consistent with observations. The large-scale response is mediated by atmospheric eddies. This implies that daily extratropical SST fluctuations must be simulated by the ocean components and resolved by the atmospheric components of global climate models to enable realistic simulation of decadal North Pacific sector climate variability.

  12. Which person variables predict how people benefit from True-False over Constructed Response items?

    Directory of Open Access Journals (Sweden)

    Stella Bollmann

    2015-06-01

    Full Text Available The aim of this study was the investigation of the variable Benefit from TF, which we assumed to be additionally measured when using True-False instead of Constructed Response tests. Subjects who benefit from True-False have an advantage over other subjects in answering Multiple Choice or True-False exams. We expected it to be related to partial knowledge and examined its relation to other personal abilities and traits in a total of n = 106 psychology students. They completed a statistics exam in Constructed Response and True-False format and benefit items were defined as those to which the associated constructed response answer was not correct. Additionally, verbal intelligence and Big 5 measures were obtained. Results confirm the existence of the person variable Benefit from TF and its relation to partial knowledge. Furthermore, benefiters differed from others in conscientiousness and openness to experience variables. However, contrary to expectations, they did not differ in verbal IQ.

  13. Ecological response of Cedrus atlantica to climate variability in the Massif of Guetiane (Algeria

    Directory of Open Access Journals (Sweden)

    Said Slimani

    2014-12-01

    Full Text Available Aim of the study: The study analyzes the long-term response of Atlas cedar, Cedrus atlantica (Manneti, to climate variability. Area of study: Atlas cedar forest of Guetiane (Batna, Algeria.Material and methods: The dendrochronological approach was adopted. An Atlas cedar tree-ring chronology was established from twenty trees. The response of the species to climate variability was assessed through the pointer years (PYs, the common climate signal among the individual chronologies, expressed by the first component (PC1, the mean sensitivity (msx, and response function and correlations analysis involving the tree-ring index and climate data (monthly mean temperature and total precipitation.Results: The highest growth variability was registered from the second half of the 20th century. The lower than the mean PYs, the PC1, and the msx increased markedly during the studied period. Dramatic increases in the PC1 and msx were detected at the end of the 1970s, reflecting a shift towards drier conditions enhancing an increasing trend towards more synchronous response of trees to climate conditions. The response function and correlations analysis showed that tree growth was mainly influenced by precipitation variability.Research highlights: Our findings provide baseline knowledge concerning the ecological response of Atlas cedar to climate variability in in its southern distribution limit, where a high level of tree mortality has been observed during recent decades, coinciding with the driest period Algeria has ever experienced. This information is vital to support ongoing ecosystem management efforts in the region. Keywords: Atlas cedar; annual growth variability; dieback; dendrochronology. 

  14. Spectral Kernel Approach to Study Radiative Response of Climate Variables and Interannual Variability of Reflected Solar Spectrum

    Science.gov (United States)

    Jin, Zhonghai; Wielicki, Bruce A.; Loukachine, Constantin; Charlock, Thomas P.; Young, David; Noeel, Stefan

    2011-01-01

    The radiative kernel approach provides a simple way to separate the radiative response to different climate parameters and to decompose the feedback into radiative and climate response components. Using CERES/MODIS/Geostationary data, we calculated and analyzed the solar spectral reflectance kernels for various climate parameters on zonal, regional, and global spatial scales. The kernel linearity is tested. Errors in the kernel due to nonlinearity can vary strongly depending on climate parameter, wavelength, surface, and solar elevation; they are large in some absorption bands for some parameters but are negligible in most conditions. The spectral kernels are used to calculate the radiative responses to different climate parameter changes in different latitudes. The results show that the radiative response in high latitudes is sensitive to the coverage of snow and sea ice. The radiative response in low latitudes is contributed mainly by cloud property changes, especially cloud fraction and optical depth. The large cloud height effect is confined to absorption bands, while the cloud particle size effect is found mainly in the near infrared. The kernel approach, which is based on calculations using CERES retrievals, is then tested by direct comparison with spectral measurements from Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY) (a different instrument on a different spacecraft). The monthly mean interannual variability of spectral reflectance based on the kernel technique is consistent with satellite observations over the ocean, but not over land, where both model and data have large uncertainty. RMS errors in kernel ]derived monthly global mean reflectance over the ocean compared to observations are about 0.001, and the sampling error is likely a major component.

  15. Analytical Solution for Wave-Induced Response of Seabed with Variable Shear Modulus

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A plane strain analysis based on the generalized Biot's equation is utilized to investigate the wave-induced response of a poro-elastic seabed with variable shear modulus. By employing integral transform and Frobenius methods, the transient and steady solutions for the wave-induced pore water pressure, effective stresses and displacements are analytically derived in detail. Verification is available through the reduction to the simple case of homogeneous seabed. The numerical results indicate that the inclusion of variable shear modulus significantly affects the wave-induced seabed response.

  16. Variable salinity responses of 12 alfalfa genotypes and comparative expression analyses of salt-response genes

    Science.gov (United States)

    Twelve alfalfa genotypes that were selected for biomass under salinity, differences in Na and Cl concentrations in shoots and K/Na ratio were evaluated in this long-term salinity experiment. The selected plants were cloned to reduce genetic variability within each genotype. Salt tolerance (ST) index...

  17. Mind-Wandering at the fingertips: automatic parsing of subjective states based on response time variability

    Directory of Open Access Journals (Sweden)

    Mikael eBastian

    2013-09-01

    Full Text Available Research from the last decade has successfully used two kinds of thought reports in order to probe whether the mind is wandering: random thought-probes and spontaneous reports. However, none of these two methods allows any assessment of the subjective state of the participant between two reports. In this paper, we present a step by step elaboration and testing of a continuous index, based on response time variability within Sustained Attention to Response Tasks (N=106, for a total of 10 conditions. We first show that increased response time variability predicts mind-wandering. We then compute a continuous index of response time variability throughout full experiments and show that the temporal position of a probe relative to the nearest local peak of the continuous index is predictive of mind-wandering. This suggests that our index carries information about the subjective state of the subject even when he or she is not probed, and opens the way for on-line tracking of mind-wandering. Finally we proceed a step further and infer the internal attentional states on the basis of the variability of response times. To this end we use the Hidden Markov Model framework, which allows us to estimate the durations of on-task and off-task episodes.

  18. Mind wandering at the fingertips: automatic parsing of subjective states based on response time variability.

    Science.gov (United States)

    Bastian, Mikaël; Sackur, Jérôme

    2013-01-01

    RESEARCH FROM THE LAST DECADE HAS SUCCESSFULLY USED TWO KINDS OF THOUGHT REPORTS IN ORDER TO ASSESS WHETHER THE MIND IS WANDERING: random thought-probes and spontaneous reports. However, none of these two methods allows any assessment of the subjective state of the participant between two reports. In this paper, we present a step by step elaboration and testing of a continuous index, based on response time variability within Sustained Attention to Response Tasks (N = 106, for a total of 10 conditions). We first show that increased response time variability predicts mind wandering. We then compute a continuous index of response time variability throughout full experiments and show that the temporal position of a probe relative to the nearest local peak of the continuous index is predictive of mind wandering. This suggests that our index carries information about the subjective state of the subject even when he or she is not probed, and opens the way for on-line tracking of mind wandering. Finally we proceed a step further and infer the internal attentional states on the basis of the variability of response times. To this end we use the Hidden Markov Model framework, which allows us to estimate the durations of on-task and off-task episodes.

  19. Neural and vascular variability and the fMRI-BOLD response in normal aging.

    Science.gov (United States)

    Kannurpatti, Sridhar S; Motes, Michael A; Rypma, Bart; Biswal, Bharat B

    2010-05-01

    Neural, vascular and structural variables contributing to the blood oxygen level-dependent (BOLD) signal response variability were investigated in younger and older humans. Twelve younger healthy human subjects (six male and six female; mean age: 24 years; range: 19-27 years) and 12 older healthy subjects (five male and seven female; mean age: 58 years; range: 55-71 years) with no history of head trauma and neurological disease were scanned. Functional magnetic resonance imaging measurements using the BOLD contrast were made when participants performed a motor, cognitive or a breath hold (BH) task. Activation volume and the BOLD response amplitude were estimated for the younger and older at both group and subject levels. Mean activation volume was reduced by 45%, 40% and 38% in the elderly group during the motor, cognitive and BH tasks, respectively, compared to the younger. Reduction in activation volume was substantially higher compared to the reduction in the gray matter volume of 14% in the older compared to the younger. A significantly larger variability in the intersubject BOLD signal change occurred during the motor task, compared to the cognitive task. BH-induced BOLD signal change between subjects was significantly less-variable in the motor task-activated areas in the younger compared to older whereas such a difference between age groups was not observed during the cognitive task. Hemodynamic scaling using the BH signal substantially reduced the BOLD signal variability during the motor task compared to the cognitive task. The results indicate that the origin of the BOLD signal variability between subjects was predominantly vascular during the motor task while being principally a consequence of neural variability during the cognitive task. Thus, in addition to gray matter differences, the type of task performed can have different vascular variability weighting that can influence age-related differences in brain functional response.

  20. Biodegradable fiksasyon malzemeleri

    OpenAIRE

    Seber, Sinan

    2004-01-01

    Problems related to metallic implant had increased the interest to biodegradables. In this paper, the physical and chemical properties, degradation modalities, implant design, clinical studies with techniques, and complications of biodegradable implants, especially polylactic and polyglycolic acid, were reviewed. Also our studies, on the antibiotic delivery capacities of these implants; and the prediction of immunological reactions with our clinical experiences were presented.

  1. Internight sleep variability: its clinical significance and responsiveness to treatment in primary and comorbid insomnia.

    Science.gov (United States)

    Sánchez-Ortuño, María M; Edinger, Jack D

    2012-10-01

    Although sleep diary and actigraphy data are usually collected daily for 1 or 2 weeks, traditional analytical approaches aggregate these data into mean values. Internight variability of sleep often accompanies insomnia. However, few studies have explored the relevance of this 'construct' in the context of diagnosis, clinical impact, treatment effects and/or whether having 'variable sleep' carries any prognostic significance. We explored these questions by conducting secondary analyses of data from a randomized clinical trial. The sample included primary (PI: n = 40) and comorbid insomnia (CMI: n = 41) sufferers receiving four biweekly sessions of cognitive-behavioural therapy (CBT) or sleep hygiene education. Using the within-subject standard deviations of diary- and actigraphy-derived measures collected for 2-week periods [sleep onset latency (SOL), wake after sleep onset (WASO), total sleep time (TST) and sleep efficiency (SE)], we found that CMI sufferers displayed more variable self-reported SOLs and SEs than PI sufferers. However, higher variability in diary and actigraphy-derived measures was related to poorer sleep quality only within the PI group, as measured by the Pittsburgh Sleep Quality Index (PSQI). Within both groups, the variability of diary-derived measures was reduced after CBT, but the variability of actigraphy-derived measures remained unchanged. Interestingly, the variability of actigraphy measures at baseline was correlated with PSQI scores at 6-month follow-up. Higher SOL variability was associated with worse treatment outcomes within the PI group, whereas higher WASO variability was correlated with better treatment outcomes within the CMI group. Sleep variability differences across insomnia diagnoses, along with their distinctive correlates, suggest that mechanisms underlying the sleep disruption/complaint and treatment response in both patient groups are distinct. Further studies are warranted to support variability as a useful metric in

  2. CRMS vegetation analytical team framework: Methods for collection, development, and use of vegetation response variables

    Science.gov (United States)

    Cretini, Kari F.; Visser, Jenneke M.; Krauss, Ken W.; Steyer, Gregory D.

    2011-01-01

    This document identifies the main objectives of the Coastwide Reference Monitoring System (CRMS) vegetation analytical team, which are to provide (1) collection and development methods for vegetation response variables and (2) the ways in which these response variables will be used to evaluate restoration project effectiveness. The vegetation parameters (that is, response variables) collected in CRMS and other coastal restoration projects funded under the Coastal Wetlands Planning, Protection and Restoration Act (CWPPRA) are identified, and the field collection methods for these parameters are summarized. Existing knowledge on community and plant responses to changes in environmental drivers (for example, flooding and salinity) from published literature and from the CRMS and CWPPRA monitoring dataset are used to develop a suite of indices to assess wetland condition in coastal Louisiana. Two indices, the floristic quality index (FQI) and a productivity index, are described for herbaceous and forested vegetation. The FQI for herbaceous vegetation is tested with a long-term dataset from a CWPPRA marsh creation project. Example graphics for this index are provided and discussed. The other indices, an FQI for forest vegetation (that is, trees and shrubs) and productivity indices for herbaceous and forest vegetation, are proposed but not tested. New response variables may be added or current response variables removed as data become available and as our understanding of restoration success indicators develops. Once indices are fully developed, each will be used by the vegetation analytical team to assess and evaluate CRMS/CWPPRA project and program effectiveness. The vegetation analytical teams plan to summarize their results in the form of written reports and/or graphics and present these items to CRMS Federal and State sponsors, restoration project managers, landowners, and other data users for their input.

  3. Interleukin-6 impairs chronotropic responsiveness to cholinergic stimulation and decreases heart rate variability in mice.

    Science.gov (United States)

    Hajiasgharzadeh, Khalil; Mirnajafi-Zadeh, Javad; Mani, Ali R

    2011-12-30

    Heart rate variability is reduced in several clinical settings associated with systemic inflammation. The underlying mechanism of decreased heart rate variability during systemic inflammation is unknown. It appears that the inflammatory cytokines might play a role, since epidemiologic studies has shown that circulating levels of interleukine-6 (IL-6) correlate significantly with indexes of depressed heart rate variability in various clinical conditions. The present investigation was carried out to study the peripheral and central effects of IL-6 on heart rate dynamic in mice. Adult male BALB/c mice were used in the study. RT-PCR was performed to study the expression of IL-6 receptor in mouse atrial and the results showed that gp130 mRNA was detectable in the atrium. The effect of IL-6 was also studies on chronotropic responsiveness of isolated atria to adrenergic and cholinergic stimulations. Incubation of isolated atria with 10 ng/ml of IL-6 was associated with a significant hypo-responsiveness to cholinergic stimulation (log IC₅₀ of carbacholine changed from -6.26±0.10 in controls to -5.59±0.19 following incubation with IL-6, Pheart rate variability parameters (SDNN, SD1, and SD2). While intracerebroventricular injection of IL-6 (50 ng/mouse) had no significant effect on heart rate variability parameters. These data are in line with a peripheral role for IL-6 in the genesis of decreased heart rate variability during systemic inflammation.

  4. Study on Short-term Variability of Ship Responses in Waves

    DEFF Research Database (Denmark)

    Nielsen, Ulrik Dam; Iseki, Toshio

    2015-01-01

    Short-term variability of ship responses is investigated by cross-spectrum analysis. In a steady state condition, it is well known that a certain length of sampled data is required for stable results of the spectral analysis. However, the phase lag between responses, in terms of the phase angle...... of the cross-spectra, has not been discussed in detail. Using long stationary time series, the transition of amplitudes and relative phase angles of the cross-spectra has been investigated by iterative analyzes with a few seconds of time shifting. In the results, the short-term variability of the relative...... phase angle was observed. In effect, the variability may compromise the accuracy of the wave buoy analogy....

  5. Bayesian modeling of measurement error in predictor variables using item response theory

    NARCIS (Netherlands)

    Fox, Jean-Paul; Glas, Cees A.W.

    2000-01-01

    This paper focuses on handling measurement error in predictor variables using item response theory (IRT). Measurement error is of great important in assessment of theoretical constructs, such as intelligence or the school climate. Measurement error is modeled by treating the predictors as unobserved

  6. Resistance to Change and Preference for Variable versus Fixed Response Sequences

    Science.gov (United States)

    Arantes, Joana; Berg, Mark E.; Le, Dien; Grace, Randolph C.

    2012-01-01

    In Experiment 1, 4 pigeons were trained on a multiple chain schedule in which the initial link was a variable-interval (VI) 20-s schedule signalled by a red or green center key, and terminal links required four responses made to the left (L) and/or right (R) keys. In the REPEAT component, signalled by red keylights, only LRLR terminal-link…

  7. A longitudinal study in youth of heart rate variability at rest and in response to stress

    NARCIS (Netherlands)

    Li, Zhibin; Snieder, Harold; Su, Shaoyong; Ding, Xiuhua; Thayer, Julian F.; Treiber, Frank A.; Wang, Xiaoling

    2009-01-01

    Background: Few longitudinal studies have examined ethnic and sex differences, predictors and tracking stabilities of heart rate variability (HRV) at rest and in response to stress in youths and young adults. Methods: Two evaluations were performed approximately 1.5 years apart on 399 youths and you

  8. Response-Time Variability Is Related to Parent Ratings of Inattention, Hyperactivity, and Executive Function

    Science.gov (United States)

    Gomez-Guerrero, Lorena; Martin, Cristina Dominguez; Mairena, Maria Angeles; Di Martino, Adriana; Wang, Jing; Mendelsohn, Alan L.; Dreyer, Benard P.; Isquith, Peter K.; Gioia, Gerard; Petkova, Eva; Castellanos, F. Xavier

    2011-01-01

    Objective: Individuals with ADHD are often characterized as inconsistent across many contexts. ADHD is also associated with deficits in executive function. We examined the relationships between response time (RT) variability on five brief computer tasks to parents' ratings of ADHD-related features and executive function in a group of children with…

  9. Study on Short-term Variability of Ship Responses in Waves

    DEFF Research Database (Denmark)

    Iseki, Toshio; Nielsen, Ulrik Dam

    2014-01-01

    Short-term variability of ship responses is investigated from the view point of cross-spectrum analysis. In a steady state condition, it is well known that a certain length of sampled data are required for stable spectral analysis. However, the phase angle of the cross-spectra has not been discus...

  10. Predictive Response Value of Pre- and Postchemoradiotherapy Variables in Rectal Cancer: An Analysis of Histological Data.

    Science.gov (United States)

    Santos, Marisa D; Silva, Cristina; Rocha, Anabela; Nogueira, Carlos; Matos, Eduarda; Lopes, Carlos

    2016-01-01

    Background. Neoadjuvant chemoradiotherapy (nCRT) followed by curative surgery in locally advanced rectal cancer (LARC) improves pelvic disease control. Survival improvement is achieved only if pathological response occurs. Mandard tumor regression grade (TRG) proved to be a valid system to measure nCRT response. Potential predictive factors for Mandard response are analyzed. Materials and Methods. 167 patients with LARC were treated with nCRT and curative surgery. Tumor biopsies and surgical specimens were reviewed and analyzed regarding mitotic count, necrosis, desmoplastic reaction, and inflammatory infiltration grade. Surgical specimens were classified according to Mandard TRG. The patients were divided as "good responders" (Mandard TRG1-2) and "bad responders" (Mandard TRG3-5). According to results from our previous data, good responders have better prognosis than bad responders. We examined predictive factors for Mandard response and performed statistical analysis. Results. In univariate analysis, distance from anal verge and ten other postoperative variables related with nCRT tumor response had predictive value for Mandard response. In multivariable analysis only mitotic count, necrosis, and differentiation grade in surgical specimen had predictive value. Conclusions. There is a lack of clinical and pathological preoperative variables able to predict Mandard response. Only postoperative pathological parameters related with nCRT response have predictive value.

  11. A Sensitive and Biodegradable Pressure Sensor Array for Cardiovascular Monitoring.

    Science.gov (United States)

    Boutry, Clementine M; Nguyen, Amanda; Lawal, Qudus Omotayo; Chortos, Alex; Rondeau-Gagné, Simon; Bao, Zhenan

    2015-11-18

    An array of highly sensitive pressure sensors entirely made of biodegradable materials is presented, designed as a single-use flexible patch for application in cardiovascular monitoring. The high sensitivity in combination with fast response time is unprecedented when compared to recent reports on biodegradable pressure sensors (sensitivity three orders of magnitude higher), as illustrated by pulse wave velocity measurements, toward hypertension detection.

  12. Inter-individual variability of stone marten behavioral responses to a highway.

    Directory of Open Access Journals (Sweden)

    Fernando Ascensão

    Full Text Available Efforts to reduce the negative impacts of roads on wildlife may be hindered if individuals within the population vary widely in their responses to roads and mitigation strategies ignore this variability. This knowledge is particularly important for medium-sized carnivores as they are vulnerable to road mortality, while also known to use available road passages (e.g., drainage culverts for safely crossing highways. Our goal in this study was to assess whether this apparently contradictory pattern of high road-kill numbers associated with a regular use of road passages is attributable to the variation in behavioral responses toward the highway between individuals. We investigated the responses of seven radio-tracked stone martens (Martes foina to a highway by measuring their utilization distribution, response turning angles and highway crossing patterns. We compared the observed responses to simulated movement parameterized by the observed space use and movement characteristics of each individual, but naïve to the presence of the highway. Our results suggested that martens demonstrate a diversity of responses to the highway, including attraction, indifference, or avoidance. Martens also varied in their highway crossing patterns, with some crossing repeatedly at the same location (often coincident with highway passages. We suspect that the response variability derives from the individual's familiarity of the landscape, including their awareness of highway passage locations. Because of these variable yet potentially attributable responses, we support the use of exclusionary fencing to guide transient (e.g., dispersers individuals to existing passages to reduce the road-kill risk.

  13. Emotional contagion, empathic concern and communicative responsiveness as variables affecting nurses' stress and occupational commitment.

    Science.gov (United States)

    Omdahl, B L; O'Donnell, C

    1999-06-01

    Based on data gathered from registered nurses at two hospitals, this research examined the extent to which empathy variables contributed to nursing stress and occupational commitment. The empathy variables examined were emotional contagion (i.e. sharing the emotions of patients), empathic concern (i.e. being concerned for patients) and communicative effectiveness (i.e. effectively communicating with patients and their families). Nursing stress was explored through the variables of depersonalization, reduced personal accomplishment and emotional exhaustion. Multiple regression analyses revealed that the combination of the three emotional communication variables explained significant proportions of the variance in all three of the stress variables, as well as occupational commitment. The analyses further revealed that a lack of empathic concern and poor communicative responsiveness accounted for significant proportions of the variance in depersonalization. Lack of empathic concern, poor communicative responsiveness and high emotional contagion significantly contributed to reduced personal accomplishment. Emotional contagion explained a significant proportion of the variance in emotional exhaustion. Emotional contagion also significantly reduced occupational commitment. The findings are discussed in terms of nursing education and administration.

  14. Deconstructing an Atmospheric Model: Variability and Response, Unstable Periodic Orbits, and the Fluctuation-Dissipation Theorem

    Science.gov (United States)

    Gritsun, Andrei; Lucarini, Valerio

    2016-04-01

    Unstable periodic orbits (UPOs) provide the so-called skeletal dynamics of a sufficiently well-behaved chaotic dynamical system and provide a powerful tool for relating the response of the system to its variability. In fact, UPOs constitute natural modes of variability of the system, and resonant behaviour of the response of the system to can be associated to good correspondence between the geometry of one UPO and of the forcing term and between their periodicities. We have here analyzed a simple barotropic model of the atmosphere and constructed and found algorithmically a large number of UPOs. We have then studied the change in the climate resulting from changes in the forcing, in the orography, and in the Eckman friction. The most interesting result is the presence of a strong resonance in the orographic response on time scales of the order of about 3 days, corresponding to forced waves. Interestingly, such a spectral feature is entirely absent from the natural variability of the system and correspond to the excitation of a specific group of UPOs. This clarifies the fact that, as opposed to the case of quasi-equilibrium systems, it is far from obvious to associate forced and free variability in the spirit of the fluctuation-dissipation theorem (FDT). Reassuringly, ysing the complementary point of view of covariant Lyapunov vectors, we discover that the forcing projects substantially in the stable direction of the flow, which is exactly the mathematical setting under which the FDT cannot be applied.

  15. The contribution of interindividual factors to variability of response in transcranial direct current stimulation studies

    Directory of Open Access Journals (Sweden)

    Lucia M Li

    2015-05-01

    Full Text Available There has been an explosion of research using transcranial direct current stimulation (tDCS for investigating and modulating human cognitive and motor function in healthy populations. It has also been used in many studies seeking to improve deficits in disease populations. With the slew of studies reporting ‘promising results’ for everything from motor recovery after stroke to boosting memory function, one could be easily seduced by the idea of tDCS being the next panacea for all neurological ills. However, huge variability exists in the reported effects of tDCS, with great variability in the effect sizes and even contradictory results reported. In this review, we consider the interindividual factors that may contribute to this variability. In particular, we discuss the importance of baseline neuronal state and features, anatomy, age and the inherent variability in the injured brain. We additionally consider how interindividual variability affects the results of motor evoked potential (MEP testing with transcranial magnetic stimulation (TMS, which, in turn, can lead to apparent variability in response to tDCS in motor studies.

  16. pH-Responsive biodegradable polymeric micelles with anchors to interface magnetic nanoparticles for MR imaging in detection of cerebral ischemic area

    Science.gov (United States)

    Yang, Hong Yu; Jang, Moon-Sun; Gao, Guang Hui; Lee, Jung Hee; Lee, Doo Sung

    2016-06-01

    A novel type of pH-responsive biodegradable copolymer was developed based on methyloxy-poly(ethylene glycol)-block-poly[dopamine-2-(dibutylamino) ethylamine-l-glutamate] (mPEG-b-P(DPA-DE)LG) and applied to act as an intelligent nanocarrier system for magnetic resonance imaging (MRI). The mPEG-b-P(DPA-DE)LG copolymer was synthesized by a typical ring opening polymerization of N-carboxyanhydrides (NCAs-ROP) using mPEG-NH2 as a macroinitiator, and two types of amine-terminated dopamine groups and pH-sensitive ligands were grafted onto a side chain by a sequential aminolysis reaction. This design greatly benefits from the addition of the dopamine groups to facilitate self-assembly, as these groups can act as high-affinity anchors for iron oxide nanoparticles, thereby increasing long-term stability at physiological pH. The mPEG moiety in the copolymers helped the nanoparticles to remain well-dispersed in an aqueous solution, and pH-responsive groups could control the release of hydrophobic Fe3O4 nanoparticles in an acidic environment. The particle size of the Fe3O4-loaded mPEG-b-P(DPA-DE)LG micelles was measured by dynamic light scattering (DLS) and cryo-TEM. The superparamagnetic properties of the Fe3O4-loaded mPEG-b-P(DPA-DE)LG micelles were confirmed by a superconducting quantum interference device (SQUID). T2-weighted magnetic resonance imaging (MRI) of Fe3O4-loaded mPEG-b-P(DPA-DE)LG phantoms exhibited enhanced negative contrast with an r2 relaxivity of approximately 106.7 mM-1 s-1. To assess the ability of the Fe3O4-loaded mPEG-P(DE-DPA)LG micelles to act as MRI probes, we utilized a cerebral ischemia disease rat model with acidic tissue. We found that a gradual change in contrast in the cerebral ischemic area could be visualized by MRI after 1 h, and maximal signal loss was detected after 24 h post-injection. These results demonstrated that the Fe3O4-loaded mPEG-b-P(DPA-DE)LG micelles can act as pH-triggered MRI probes for diagnostic imaging of acidic

  17. Biodegradation of malachite green by Ochrobactrum sp.

    Science.gov (United States)

    Vijayalakshmidevi, S R; Muthukumar, Karuppan

    2014-02-01

    This study presents the biodegradation of malachite green (MG), a triphenylmethane dye, using a novel microorganism isolated from textile effluent contaminated environment. The organism responsible for degradation was identified as Ochrobactrum sp JN214485 by 16S rRNA analysis. The effect of operating parameters such as temperature, pH, immobilized bead loading, and initial dye concentration on % degradation was studied, and their optimal values were found to be 30 °C, 6, 20 g/L and 100 mg/L, respectively. The analysis showed that the extracellular enzymes were responsible for the degradation. The biodegradation of MG was confirmed by UV-visible spectroscopic and FTIR analysis. The phytotoxicity test concluded that the degradation products were less toxic compared to MG. The kinetics of biodegradation was studied and the activation energy was found to be 10.65 kcal/mol.

  18. Plant Functional Variability in Response to Late-Quaternary Climate Change Recorded in Ancient Packrat Middens

    Science.gov (United States)

    Holmgren, C. A.; Potts, D. L.

    2006-12-01

    Responses of plant functional traits to environmental variability are of enduring interest because they constrain organism performance and ecosystem function. However, most inferences regarding plant functional trait response to climatic variability have been limited to the modern period. To better understand plant functional response to long-term climate variability and how adjustments in leaf morphology may contribute to patterns of species establishment, persistence, or extirpation, we measured specific leaf area (SLA) from macrofossils preserved in ancient packrat middens collected along the Arizona/New Mexico border, USA. Our record spanned more than 32,000 years and included six woodland and Chihuahuan Desert species: Berberis cf. haematocarpa, Juniperus cf. coahuilensis, Juniperus osteosperma, Larrea tridentata, Prosopis glandulosa and Parthenium incanum. We predicted that regional climatic warming and drying since the late Pleistocene would result in intraspecific decreases in SLA. As predicted, SLA was positively correlated with midden age for three of the six species (L. tridentata, J. osteosperma, B. cf. haematocarpa). SLA was also negatively correlated with December (L. tridentata, J. cf. coahuilensis) or June (B. cf. haematocarpa, J. osteosperma) insolation. A unique record of vegetation community dynamics, plant macrofossils preserved in packrat middens also represent a rich and largely untapped source of information on long-term trends in species functional response to environmental change.

  19. BIODEGRADABLE MICROSPHERES: A REVIEW

    Directory of Open Access Journals (Sweden)

    Kaur Dupinder

    2012-12-01

    Full Text Available Microspheres are characteristically free flowing powders consisting of proteins or synthetic polymers having a particle size ranging from 1-1000 μm. The range of techniques for the preparation of microspheres offers a variety of opportunities to control aspects of drug administration and enhance the therapeutic efficacy of a given drug. Of the many polymeric drug delivery systems, biodegradable polymers have been used widely as drug delivery systems because of their biocompatibility and biodegradability. The majority of biodegradable polymers have been used in the form of microparticles, from which the incorporated drug is released to the environment in a controlled manner. They can be employed to deliver medication in a rate-controlled and sometimes targeted manner. Medication is released from a microsphere by drug leaching from the polymer or by degradation of the polymer matrix. This review discusses characteristics and degradation behaviors of biodegradable polymers which are currently used in drug delivery.

  20. Variable salinity responses of 12 alfalfa genotypes and comparative expression analyses of salt-response genes

    Science.gov (United States)

    Sandhu, Devinder; Cornacchione, Monica V.; Ferreira, Jorge F. S.; Suarez, Donald L.

    2017-01-01

    Twelve alfalfa genotypes that were selected for biomass under salinity, differences in Na and Cl concentrations in shoots and K/Na ratio were evaluated in this long-term salinity experiment. The selected plants were cloned to reduce genetic variability within each genotype. Salt tolerance (ST) index of the genotypes ranged from 0.39 to 1. The most salt-tolerant genotypes SISA14-1 (G03) and AZ-90ST (G10), the top performers for biomass, exhibited the least effect on shoot number and height. SISA14-1 (G03) accumulated low Na and Cl under salinity. Most genotypes exhibited a net reduction in shoot Ca, Mg, P, Fe, and Cu, while Mn and Zn increased under salinity. Salinity reduced foliar area and stomatal conductance; while net photosynthetic rate and transpiration were not affected. Interestingly, salinity increased chlorophyll and antioxidant capacity in most genotypes; however neither parameter correlated well to ST index. Salt-tolerant genotypes showed upregulation of the SOS1, SOS2, SOS3, HKT1, AKT1, NHX1, P5CS1, HSP90.7, HSP81.2, HSP71.1, HSPC025, OTS1, SGF29 and SAL1 genes. Gene expression analyses allowed us to classify genotypes based on their ability to regulate different components of the salt tolerance mechanism. Pyramiding different components of the salt tolerance mechanism may lead to superior salt-tolerant alfalfa genotypes. PMID:28225027

  1. Progress of biodegradable metals

    Institute of Scientific and Technical Information of China (English)

    Huafang Li; Yufeng Zheng; Ling Qin

    2014-01-01

    Biodegradable metals (BMs) are metals and alloys expected to corrode gradually in vivo, with an appropriate host response elicited by released corrosion products, then dissolve completely upon fulfilling the mission to assist with tissue healing with no implant residues. In the present review article, three classes of BMs have been systematically reviewed, including Mg-based, Fe-based and Zn-based BMs. Among the three BM systems, Mg-based BMs, which now have several systems reported the successful of clinical trial results, are considered the vanguards and main force. Fe-based BMs, with pure iron and Fe–Mn based alloys as the most promising, are still on the animal test stage. Zn-based BMs, supposed to have the degradation rate between the fast Mg-based BMs and the slow Fe-based BMs, are a rising star with only several reports and need much further research. The future research and development direction for the BMs are proposed, based on the clinical requirements on controllable degradation rate, prolonged mechanical stability and excellent biocompat-ibility, by optimization of alloy composition design, regulation on microstructure and mechanical properties, and following surface modification.

  2. Progress of biodegradable metals

    Directory of Open Access Journals (Sweden)

    Huafang Li

    2014-10-01

    Full Text Available Biodegradable metals (BMs are metals and alloys expected to corrode gradually in vivo, with an appropriate host response elicited by released corrosion products, then dissolve completely upon fulfilling the mission to assist with tissue healing with no implant residues. In the present review article, three classes of BMs have been systematically reviewed, including Mg-based, Fe-based and Zn-based BMs. Among the three BM systems, Mg-based BMs, which now have several systems reported the successful of clinical trial results, are considered the vanguards and main force. Fe-based BMs, with pure iron and Fe–Mn based alloys as the most promising, are still on the animal test stage. Zn-based BMs, supposed to have the degradation rate between the fast Mg-based BMs and the slow Fe-based BMs, are a rising star with only several reports and need much further research. The future research and development direction for the BMs are proposed, based on the clinical requirements on controllable degradation rate, prolonged mechanical stability and excellent biocompatibility, by optimization of alloy composition design, regulation on microstructure and mechanical properties, and following surface modification.

  3. Characterizing climate predictability and model response variability from multiple initial condition and multi-model ensembles

    CERN Document Server

    Kumar, Devashish

    2016-01-01

    Climate models are thought to solve boundary value problems unlike numerical weather prediction, which is an initial value problem. However, climate internal variability (CIV) is thought to be relatively important at near-term (0-30 year) prediction horizons, especially at higher resolutions. The recent availability of significant numbers of multi-model (MME) and multi-initial condition (MICE) ensembles allows for the first time a direct sensitivity analysis of CIV versus model response variability (MRV). Understanding the relative agreement and variability of MME and MICE ensembles for multiple regions, resolutions, and projection horizons is critical for focusing model improvements, diagnostics, and prognosis, as well as impacts, adaptation, and vulnerability studies. Here we find that CIV (MICE agreement) is lower (higher) than MRV (MME agreement) across all spatial resolutions and projection time horizons for both temperature and precipitation. However, CIV dominates MRV over higher latitudes generally an...

  4. Long-term successional forest dynamics: species and community responses to climatic variability

    Energy Technology Data Exchange (ETDEWEB)

    Kardol, Paul [ORNL; Todd Jr, Donald E [ORNL; Hanson, Paul J [ORNL; Mulholland, Patrick J [ORNL

    2010-01-01

    Question: Are tree dynamics sensitive to climatic variability, and do tree species differ in their responses to climatic variability? Hence, is vulnerability of forest communities to climatic variability depending on stand composition? Location: Mixed young forest at Walker Branch Watershed near Oak Ridge, East-Tennessee, USA. Methods: Using a long-term data set (1967-2006), we analyzed temporal forest dynamics at the tree and species level, and we analyzed community dynamics for forest stands that different in their initial species composition (i.e., Chestnut Oak, Oak-Hickory, Pine, and Yellow poplar stands). Using summer drought and growing season temperature as defined climate drivers, we evaluated relationships between forest dynamics and climate across levels of organization. Results: Over the 4-decade studied period, forest communities underwent successional change and substantially increased their biomass. Variation in summer drought and growing season temperature contributed to temporal biomass dynamics for some tree species, but not for others. Stand-level responses to climatic variability were shown to be related to responses of specific component species; however, not for Pine stands. Pinus echinata, the dominant species in stands initially identified as Pine stands, decreased over time due to periodical outbreaks of the pine bark beetle (Dendroctonus frontalis). The outbreaks on Walker Branch could not be directly related to climatic conditions. Conclusions: Our results imply that vulnerability of developing forests to predicted climate conditions is stand-type dependent, and hence, is a function of species composition. Autogenic successional processes (or insect outbreaks) were found to prevail over climatic variability in determining long-term forest dynamics for stands dominated by sensitive species, emphasizing the importance of studying interactions between forest succession and climate change.

  5. Responses of Montane Forest to Climate Variability in the Central Himalayas of Nepal

    Directory of Open Access Journals (Sweden)

    Janardan Mainali

    2015-02-01

    Full Text Available Climate changes are having dramatic ecological impacts in mid- to high-latitude mountain ranges where growth conditions are limited by climatic variables such as duration of growing season, moisture, and ambient temperature. We document patterns of forest vegetative response for 5 major alpine forest communities to current climate variability in the central Himalayas of Nepal to provide a baseline for assessment of future changes, as well as offer some insight into the trajectory of these changes over time. We used mean monthly surface air temperature and rainfall and the monthly averaged normalized difference vegetation index (NDVI to compare relative vegetation productivity among forest types and in relation to both climatic variables. Because changes in temperature and precipitation are directly manifested as changes in phenology, we examined current vegetative responses to climate variability in an effort to determine which climate variable is most critical for different alpine forest types. Our results show that correlations differ according to vegetation type and confirm that both precipitation and temperature affect monthly NDVI values, though more significant correlations were found with temperature data. The temperature response was more consistent because at the maximum increased temperatures, there was still an ongoing increase in vegetative vigor. This indicates that temperature is still the major limiting factor for plant growth at higher-elevation sites. This part of the Himalayas has abundant moisture, and some forest types are already saturated in terms of growth in relation to precipitation. Clear increases in productivity are documented on the upper treeline ecotones, and these systems are likely to continue to have increasing growth rates.

  6. Land surface phenological response to decadal climate variability across Australia using satellite remote sensing

    Directory of Open Access Journals (Sweden)

    M. Broich

    2014-05-01

    Full Text Available Land surface phenological cycles of vegetation greening and browning are influenced by variability in climatic forcing. Quantitative information on phenological cycles and their variability is important for agricultural applications, wildfire fuel accumulation, land management, land surface modeling, and climate change studies. Most phenology studies have focused on temperature-driven Northern Hemisphere systems, where phenology shows annually reoccurring patterns. Yet, precipitation-driven non-annual phenology of arid and semi-arid systems (i.e. drylands received much less attention, despite the fact that they cover more than 30% of the global land surface. Here we focused on Australia, the driest inhabited continent with one of the most variable rainfall climates in the world and vast areas of dryland systems. Detailed and internally consistent studies investigating phenological cycles and their response to climate variability across the entire continent designed specifically for Australian dryland conditions are missing. To fill this knowledge gap and to advance phenological research, we used existing methods more effectively to study geographic and climate-driven variability in phenology over Australia. We linked derived phenological metrics with rainfall and the Southern Oscillation Index (SOI. We based our analysis on Enhanced Vegetation Index (EVI data from the MODerate Resolution Imaging Spectroradiometer (MODIS from 2000 to 2013, which included extreme drought and wet years. We conducted a continent-wide investigation of the link between phenology and climate variability and a more detailed investigation over the Murray–Darling Basin (MDB, the primary agricultural area and largest river catchment of Australia. Results showed high inter- and intra-annual variability in phenological cycles. Phenological cycle peaks occurred not only during the austral summer but at any time of the year, and their timing varied by more than a month in

  7. Identification of key factors that reduce the variability of the single photon response.

    Science.gov (United States)

    Caruso, Giovanni; Bisegna, Paolo; Andreucci, Daniele; Lenoci, Leonardo; Gurevich, Vsevolod V; Hamm, Heidi E; DiBenedetto, Emmanuele

    2011-05-10

    Rod photoreceptors mediate vision in dim light. Their biological function is to discriminate between distinct, very low levels of illumination, i.e., they serve as reliable photon counters. This role requires high reproducibility of the response to a particular number of photons. Indeed, single photon responses demonstrate unexpected low variability, despite the stochastic nature of the individual steps in the transduction cascade. We analyzed individual system mechanisms to identify their contribution to variability suppression. These include: (i) cooperativity of the regulation of the second messengers; (ii) diffusion of cGMP and Ca(2+) in the cytoplasm; and (iii) the effect of highly localized cGMP hydrolysis by activated phosphodiesterase resulting in local saturation. We find that (i) the nonlinear relationships between second messengers and current at the plasma membrane, and the cGMP hydrolysis saturation effects, play a major role in stabilizing the system; (ii) the presence of a physical space where the second messengers move by Brownian motion contributes to stabilization of the photoresponse; and (iii) keeping Ca(2+) at its dark level has only a minor effect on the variability of the system. The effects of diffusion, nonlinearity, and saturation synergize in reducing variability, supporting the notion that the observed high fidelity of the photoresponse is the result of global system function of phototransduction.

  8. ltm: An R Package for Latent Variable Modeling and Item Response Analysis

    Directory of Open Access Journals (Sweden)

    Dimitris Rizopoulos

    2006-11-01

    Full Text Available The R package ltm has been developed for the analysis of multivariate dichotomous and polytomous data using latent variable models, under the Item Response Theory approach. For dichotomous data the Rasch, the Two-Parameter Logistic, and Birnbaum's Three-Parameter models have been implemented, whereas for polytomous data Semejima's Graded Response model is available. Parameter estimates are obtained under marginal maximum likelihood using the Gauss-Hermite quadrature rule. The capabilities and features of the package are illustrated using two real data examples.

  9. Eddy heat flux in the Southern Ocean: response to variable wind forcing

    OpenAIRE

    Hogg, Andrew Mcc.; Meredith, Michael P.; Blundell, Jeffrey R.; Wilson, Christopher

    2008-01-01

    We assess the role of time-dependent eddy variability in the Antarctic Circumpolar Current (ACC) in influencing warming of the Southern Ocean. For this, we use an eddy-resolving quasigeostrophic model of the wind-driven circulation, and quantify the response of circumpolar transport, eddy kinetic energy and eddy heat transport to changes in winds. On interannual timescales, the model exhibits the behaviour of an "eddy saturated" ocean state, where increases in wind stress do not signicantly ...

  10. Fast corrective responses are evoked by perturbations approaching the natural variability of posture and movement tasks.

    Science.gov (United States)

    Crevecoeur, F; Kurtzer, I; Scott, S H

    2012-05-01

    A wealth of studies highlight the importance of rapid corrective responses during voluntary motor tasks. These studies used relatively large perturbations to evoke robust muscle activity. Thus it remains unknown whether these corrective responses (latency 20-100 ms) are evoked at perturbation levels approaching the inherent variability of voluntary control. To fill this gap, we examined responses for large to small perturbations applied while participants either performed postural or reaching tasks. To address multijoint corrective responses, we induced various amounts of single-joint elbow motion with scaled amounts of combined elbow and shoulder torques. Indeed, such perturbations are known to elicit a response at the unstretched shoulder muscle, which reflects an internal model of arm intersegmental dynamics. Significant muscle responses were observed during both postural control and reaching, even when perturbation-related joint angle, velocity, and acceleration overlapped in distribution with deviations encountered in unperturbed trials. The response onsets were consistent across the explored range of perturbation loads, with short-latency onset for the muscles spanning the elbow joints (20-40 ms), and long-latency for shoulder muscles (onset > 45 ms). In addition, the evoked activity was strongly modulated by perturbation magnitude. These results suggest that multijoint responses are not specifically engaged to counter motor errors that exceed a certain threshold. Instead, we suggest that these corrective processes operate continuously during voluntary motor control.

  11. A case study of alternative site response explanatory variables in Parkfield, California

    Science.gov (United States)

    Thompson, E.M.; Baise, L.G.; Kayen, R.E.; Morgan, E.C.; Kaklamanos, J.

    2011-01-01

    The combination of densely-spaced strong-motion stations in Parkfield, California, and spectral analysis of surface waves (SASW) profiles provides an ideal dataset for assessing the accuracy of different site response explanatory variables. We judge accuracy in terms of spatial coverage and correlation with observations. The performance of the alternative models is period-dependent, but generally we observe that: (1) where a profile is available, the square-root-of-impedance method outperforms VS30 (average S-wave velocity to 30 m depth), and (2) where a profile is unavailable, the topographic-slope method outperforms surficial geology. The fundamental site frequency is a valuable site response explanatory variable, though less valuable than VS30. However, given the expense and difficulty of obtaining reliable estimates of VS30 and the relative ease with which the fundamental site frequency can be computed, the fundamental site frequency may prove to be a valuable site response explanatory variable for many applications. ?? 2011 ASCE.

  12. Mass Market Demand Response and Variable Generation Integration Issues: A Scoping Study

    Energy Technology Data Exchange (ETDEWEB)

    Cappers, Peter; Mills, Andrew; Goldman, Charles; Wiser, Ryan; Eto, Joseph H.

    2011-09-10

    This scoping study focuses on the policy issues inherent in the claims made by some Smart Grid proponents that the demand response potential of mass market customers which is enabled by widespread implementation of Advanced Metering Infrastructure (AMI) through the Smart Grid could be the “silver bullet” for mitigating variable generation integration issues. In terms of approach, we will: identify key issues associated with integrating large amounts of variable generation into the bulk power system; identify demand response opportunities made more readily available to mass market customers through widespread deployment of AMI systems and how they can affect the bulk power system; assess the extent to which these mass market Demand Response (DR) opportunities can mitigate Variable Generation (VG) integration issues in the near-term and what electricity market structures and regulatory practices could be changed to further expand the ability for DR to mitigate VG integration issues over the long term; and provide a qualitative comparison of DR and other approaches to mitigate VG integration issues.

  13. Peri-implant tissue response and biodegradation performance of a Mg-1.0Ca-0.5Sr alloy in rat tibia.

    Science.gov (United States)

    Berglund, Ida S; Jacobs, Brittany Y; Allen, Kyle D; Kim, Stanley E; Pozzi, Antonio; Allen, Josephine B; Manuel, Michele V

    2016-05-01

    Biodegradable magnesium (Mg) alloys combine the advantages of traditional metallic implants and biodegradable polymers, having high strength, low density, and a stiffness ideal for bone fracture fixation. A recently developed Mg-Ca-Sr alloy potentially possesses advantageous characteristics over other Mg alloys, such as slower degradation rates and minimal toxicity. In this study, the biocompatibility of this Mg-Ca-Sr alloy was investigated in a rat pin-placement model. Cylindrical pins were inserted in the proximal tibial metaphyses in pre-drilled holes orthogonal to the tibial axis. Implant and bone morphologies were investigated using μCT at 1, 3, and 6 weeks after implant placement. At the same time points, the surrounding tissue was evaluated using H&E, TRAP and Goldner's trichrome staining. Although gas bubbles were observed around the degrading implant at early time points, the bone remained intact with no evidence of microfracture. Principle findings also include new bone formation in the area of the implant, suggesting that the alloy is a promising candidate for biodegradable orthopedic implants.

  14. Behavioral variability, elimination of responses, and delay-of-reinforcement gradients in SHR and WKY rats

    Directory of Open Access Journals (Sweden)

    Killeen Peter R

    2007-11-01

    Full Text Available Abstract Background Attention-deficit/hyperactivity disorder (ADHD is characterized by a pattern of inattention, hyperactivity, and impulsivity that is cross-situational, persistent, and produces social and academic impairment. Research has shown that reinforcement processes are altered in ADHD. The dynamic developmental theory has suggested that a steepened delay-of-reinforcement gradient and deficient extinction of behavior produce behavioral symptoms of ADHD and increased behavioral variability. Method The present study investigated behavioral variability and elimination of non-target responses during acquisition in an animal model of ADHD, the spontaneously hypertensive rat (SHR, using Wistar Kyoto (WKY rats as controls. The study also aimed at providing a novel approach to measuring delay-of-reinforcement gradients in the SHR and the WKY strains. The animals were tested in a modified operant chamber presenting 20 response alternatives. Nose pokes in a target hole produced water according to fixed interval (FI schedules of reinforcement, while nose pokes in the remaining 19 holes either had no consequences or produced a sound or a short flickering of the houselight. The stimulus-producing holes were included to test whether light and sound act as sensory reinforcers in SHR. Data from the first six sessions testing FI 1 s were used for calculation of the initial distribution of responses. Additionally, Euclidean distance (measured from the center of each hole to the center of the target hole and entropy (a measure of variability were also calculated. Delay-of-reinforcement gradients were calculated across sessions by dividing the fixed interval into epochs and determining how much reinforcement of responses in one epoch contributed to responding in the next interval. Results Over the initial six sessions, behavior became clustered around the target hole. There was greater initial variability in SHR behavior, and slower elimination of

  15. Variability of fMRI-response patterns at different spatial observation scales.

    Science.gov (United States)

    Ball, Tonio; Breckel, Thomas P K; Mutschler, Isabella; Aertsen, Ad; Schulze-Bonhage, Andreas; Hennig, Jürgen; Speck, Oliver

    2012-05-01

    Functional organization units of the cerebral cortex exist over a wide range of spatial scales, from local circuits to entire cortical areas. In the last decades, scale-space representations of neuroimaging data suited to probe the multi-scale nature of cortical functional organization have been introduced and methodologically elaborated. For this purpose, responses are statistically detected over a range of spatial scales using a family of Gaussian filters, with small filters being related to fine and large filters-to coarse spatial scales. The goal of the present study was to investigate the degree of variability of fMRI-response patterns over a broad range of observation scales. To this aim, the same fMRI data set obtained from 18 subjects during a visuomotor task was analyzed with a range of filters from 4- to 16-mm full width at half-maximum (FWHM). We found substantial observation-scale-related variability. For example, using filter widths of 6- to 8-mm FWHM, in the group-level results, significant responses in the right secondary visual but not in the primary visual cortex were detected. However, when larger filters were used, the responses in the right primary visual cortex reached significance. Often, responses in probabilistically defined areas were significant when both small and large filters, but not intermediate filter widths were applied. This suggests that brain responses can be organized in local clusters of multiple distinct activation foci. Our findings illustrate the potential of multi-scale fMRI analysis to reveal novel features in the spatial organization of human brain responses.

  16. Comparative Study on Response Surfaces for Reliability Analysis of Spatially Variable Soil Slope

    Institute of Scientific and Technical Information of China (English)

    李亮; 褚雪松

    2015-01-01

    This paper focuses on the performance of the second-order polynomial-based response surfaces on the reliability of spatially variable soil slope. A single response surface constructed to approximate the slope system failure performance functionG(X) (called single RS) and multiple response surfaces constructed on finite number of slip surfaces (called multiple RS) are developed, respectively. Single RS and multiple RS are applied to evaluate the system failure probability pf for a cohesive soil slope together with Monte Carlo simulation (MCS). It is found thatpf calculated by single RS deviates significantly from that obtained by searching a large number of potential slip surfaces, and this deviation becomes insignificant with the decrease of the number of random variables or the increase of the scale of fluctuation. In other words, single RS cannot approximateG(X) with reasonable accuracy. The value ofpf from multiple response surfaces fits well with that obtained by searching a large number of potential slip surfaces. That is, multiple RS can estimateG(X) with reasonable accuracy.

  17. Amygdala and heart rate variability responses from listening to emotionally intense parts of a story

    DEFF Research Database (Denmark)

    Wallentin, Mikkel; Nielsen, Andreas Højlund; Vuust, Peter;

    2011-01-01

    part of the system for processing conditioned emotional responses to auditory stimuli. These findings suggest that this system also underpins narrative emotions in spite of their complex nature. Traditional language regions and premotor cortices were also activated during intense parts of the story......Emotions are often understood in relation to conditioned responses. Narrative emotions, however, cannot be reduced to a simple associative relationship between emotion words and their experienced counterparts. Intensity in stories may arise without any overt emotion depicting words and vice versa....... In this fMRI study we investigated BOLD-responses to naturally fluctuating emotions evoked by listening to a story. The emotional intensity profile of the text was found through a rating study. The validity of this profile was supported by heart rate variability (HRV) data showing a significant...

  18. Acute marijuana effects on response-reinforcer relations under multiple variable-interval schedules.

    Science.gov (United States)

    Lane, S D; Cherek, D R; Pietras, C J; Tcheremissine, O V

    2004-07-01

    Acute marijuana administration may alter response-reinforcer relationships via a change in reinforcer efficacy, but may also impair coordination and motor function. One approach to evaluating drug effects on both motor function and reinforcer efficacy involves fitting the matching law equation to data obtained under multiple variable interval (VI) schedules. The present report describes an experiment that examined the effects of acute marijuana on response properties using this approach. Six human subjects responded under a multiple VI schedule for monetary reinforcers after smoking placebo and two active doses of marijuana. The low marijuana dose produced unsystematic changes in responding. As measured by the matching law equation parameters (k and rB), at the high dose five subjects showed a decrease-motor-related properties of response rate and four subjects' responding indicated a decrease in reinforcer efficacy. These data raise the possibility that, at high doses, marijuana administration alters both motor function and reinforcer efficacy.

  19. Major Crop Species Show Differential Balance between Root Morphological and Physiological Responses to Variable Phosphorus Supply

    Science.gov (United States)

    Lyu, Yang; Tang, Hongliang; Li, Haigang; Zhang, Fusuo; Rengel, Zed; Whalley, William R.; Shen, Jianbo

    2016-01-01

    The relationship between root morphological and physiological responses to variable P supply in different plant species is poorly understood. We compared root morphological and physiological responses to P supply in seven crop species (Zea mays, Triticum aestivum, Brassica napus, Lupinus albus, Glycine max, Vicia faba, Cicer arietinum) treated with or without 100 mg P kg-1 in two soils (acidic and calcareous). Phosphorus deficiency decreased root length more in fibrous root species (Zea mays, Triticum aestivum, Brassica napus) than legumes. Zea mays and Triticum aestivum had higher root/shoot biomass ratio and Brassica napus had higher specific root length compared to legumes, whereas legumes (except soybean) had higher carboxylate exudation than fibrous root species. Lupinus albus exhibited the highest P-acquisition efficiency due to high exudation of carboxylates and acid phosphatases. Lupinus albus and Cicer arietinum depended mostly on root exudation (i.e., physiological response) to enhance P acquisition, whereas Zea mays, Triticum aestivum and Brassica napus had higher root morphology dependence, with Glycine max and Vicia faba in between. Principal component analysis using six morphological and six physiological responses identified root size and diameter as the most important morphological traits, whereas important physiological responses included carboxylate exudation, and P-acquisition and P-utilization efficiency followed by rhizosphere soil pH and acid phosphatase activity. In conclusion, plant species can be grouped on the basis of their response to soil P being primarily via root architectural or exudation plasticity, suggesting a potential benefit of crop-specific root-trait-based management to cope with variable soil P supply in sustainable grain production. PMID:28066491

  20. Dose Response Association between Physical Activity and Biological, Demographic, and Perceptions of Health Variables

    Directory of Open Access Journals (Sweden)

    Paul D. Loprinzi

    2013-08-01

    Full Text Available Background: Few population-based studies have examined the association between physical activity (PA and cardiovascular disease risk factors, demographic variables, and perceptions of health status, and we do not have a clear understanding of the dose-response relationship among these variables. Methods: Data from the 2003-2006 National Health and Nutrition Examination Survey was used to examine the dose-response relationship between objectively measured PA and metabolic syndrome (and its individual cardiovascular disease risk factors, demographic variables, and perceptions of health. After exclusions, 5,538 participants 18 years or older were included in the present study, with 2,538 participants providing fasting glucose and 2,527 providing fasting triglyceride data. PA was categorized into deciles. Results: Overall, the health benefits showed a general pattern of increase with each increasing levels of PA. Of the ten PA classifications examined, participants in the highest moderate-to-vigorous physical activity (MVPA category (at least 71 min/day had the lowest odds of developing metabolic syndrome. Conclusion: At a minimum, sedentary adults should strive to meet current PA guidelines (i.e., 150 min/week of MVPA, with additional positive benefits associated with engaging in three times this level of PA.

  1. Depletion and response of deep groundwater to climate-induced pumping variability

    Science.gov (United States)

    Russo, Tess A.; Lall, Upmanu

    2017-01-01

    Groundwater constitutes a critical component of our water resources. Widespread groundwater level declines have occurred in the USA over recent decades, including in regions not typically considered water stressed, such as areas of the Northwest and mid-Atlantic Coast. This loss of water storage reflects extraction rates that exceed natural recharge and capture. Here, we explore recent changes in the groundwater levels of deep aquifers from wells across the USA, and their relation to indices of interannual to decadal climate variability and to annual precipitation. We show that groundwater level changes correspond to selected global climate variations. Although climate-induced variations of deep aquifer natural recharge are expected to have multi-year time lags, we find that deep groundwater levels respond to climate over timescales of less than one year. In irrigated areas, the annual response to local precipitation in the deepest wells may reflect climate-induced pumping variability. An understanding of how the human response to drought through pumping leads to deep groundwater changes is critical to manage the impacts of interannual to decadal and longer climate variability on the nation’s water resources.

  2. Predicting gender differences as latent variables: summed scores, and individual item responses: a methods case study

    Directory of Open Access Journals (Sweden)

    Jacobs Danny O

    2004-10-01

    Full Text Available Abstract Background Modeling latent variables such as physical disability is challenging since its measurement is performed through proxies. This poses significant methodological challenges. The objective of this article is to present three different methods to predict latent variables based on classical summed scores, individual item responses, and latent variable models. Methods This is a review of the literature and data analysis using "layers of information". Data was collected from the North Carolina Back Pain Project, using a modified version of the Roland Questionnaire. Results The three models are compared in relation to their goals and underlying concepts, previous clinical applications, data requirements, statistical theory, and practical applications. Initial linear regression models demonstrated a difference in disability between genders of 1.32 points (95% CI 0.65, 2.00 on a scale from 0–23. Subsequent item analysis found contradictory results across items, with no clear pattern. Finally, IRT models demonstrated three items were demonstrated to present differential item functioning. After these items were removed, the difference between genders was reduced to 0.78 points (95% CI, -0.99, 1.23. These results were shown to be robust with re-sampling methods. Conclusions Purported differences in the levels of a latent variable should be tested using different models to verify whether these differences are real or simply distorted by model assumptions.

  3. Linear variable filter optimization for emergency response chemical detection and discrimination

    Science.gov (United States)

    Shen, Sylvia S.; Lewis, Paul E.

    2010-08-01

    Linear variable filter design and fabrication for LWIR is now commercially available for use in the development of remote sensing systems. The linear variable filter is attached directly to the cold shield of the focal plane array. The resulting compact spectrometer assemblies are completely contained in the Dewar system. This approach eliminates many of the wavelength calibration problems associated with current prism and grating systems and also facilitates the cost effective design and fabrication of aerial sensing systems for specific applications. This paper describes a study that was conducted with the following three objectives: 1) Determine if a multi-channel linear-variable-filter-based line scanner system can be used to discriminate a set of chemical vapors that represent a high probability of occurrence during a typical emergency response chemical incident; 2) Determine which multi-channel linear variable filter design is optimal; and 3) Determine the acceptable instrument noise equivalent spectral radiance for this application. A companion paper describes a separate study that was conducted to determine the concentration levels at which detection and discrimination can be achieved for the various chemicals based on the optimal filter design under various degrees of imperfect atmospheric correction.

  4. Molecularly Imprinted Biodegradable Nanoparticles

    Science.gov (United States)

    Gagliardi, Mariacristina; Bertero, Alice; Bifone, Angelo

    2017-01-01

    Biodegradable polymer nanoparticles are promising carriers for targeted drug delivery in nanomedicine applications. Molecu- lar imprinting is a potential strategy to target polymer nanoparticles through binding of endogenous ligands that may promote recognition and active transport into specific cells and tissues. However, the lock-and-key mechanism of molecular imprinting requires relatively rigid cross-linked structures, unlike those of many biodegradable polymers. To date, no fully biodegradable molecularly imprinted particles have been reported in the literature. This paper reports the synthesis of a novel molecularly- imprinted nanocarrier, based on poly(lactide-co-glycolide) (PLGA) and acrylic acid, that combines biodegradability and molec- ular recognition properties. A novel three-arm biodegradable cross-linker was synthesized by ring-opening polymerization of glycolide and lactide initiated by glycerol. The resulting macromer was functionalized by introduction of end-functions through reaction with acryloyl chloride. Macromer and acrylic acid were used for the synthesis of narrowly-dispersed nanoparticles by radical polymerization in diluted conditions in the presence of biotin as template molecule. The binding capacity of the imprinted nanoparticles towards biotin and biotinylated bovine serum albumin was twentyfold that of non-imprinted nanoparti- cles. Degradation rates and functional performances were assessed in in vitro tests and cell cultures, demonstrating effective biotin-mediated cell internalization. PMID:28071745

  5. Molecularly Imprinted Biodegradable Nanoparticles

    Science.gov (United States)

    Gagliardi, Mariacristina; Bertero, Alice; Bifone, Angelo

    2017-01-01

    Biodegradable polymer nanoparticles are promising carriers for targeted drug delivery in nanomedicine applications. Molecu- lar imprinting is a potential strategy to target polymer nanoparticles through binding of endogenous ligands that may promote recognition and active transport into specific cells and tissues. However, the lock-and-key mechanism of molecular imprinting requires relatively rigid cross-linked structures, unlike those of many biodegradable polymers. To date, no fully biodegradable molecularly imprinted particles have been reported in the literature. This paper reports the synthesis of a novel molecularly- imprinted nanocarrier, based on poly(lactide-co-glycolide) (PLGA) and acrylic acid, that combines biodegradability and molec- ular recognition properties. A novel three-arm biodegradable cross-linker was synthesized by ring-opening polymerization of glycolide and lactide initiated by glycerol. The resulting macromer was functionalized by introduction of end-functions through reaction with acryloyl chloride. Macromer and acrylic acid were used for the synthesis of narrowly-dispersed nanoparticles by radical polymerization in diluted conditions in the presence of biotin as template molecule. The binding capacity of the imprinted nanoparticles towards biotin and biotinylated bovine serum albumin was twentyfold that of non-imprinted nanoparti- cles. Degradation rates and functional performances were assessed in in vitro tests and cell cultures, demonstrating effective biotin-mediated cell internalization.

  6. Computer Optimization of Biodegradable Nanoparticles Fabricated by Dispersion Polymerization

    Directory of Open Access Journals (Sweden)

    Emmanuel O. Akala

    2015-12-01

    Full Text Available Quality by design (QbD in the pharmaceutical industry involves designing and developing drug formulations and manufacturing processes which ensure predefined drug product specifications. QbD helps to understand how process and formulation variables affect product characteristics and subsequent optimization of these variables vis-à-vis final specifications. Statistical design of experiments (DoE identifies important parameters in a pharmaceutical dosage form design followed by optimizing the parameters with respect to certain specifications. DoE establishes in mathematical form the relationships between critical process parameters together with critical material attributes and critical quality attributes. We focused on the fabrication of biodegradable nanoparticles by dispersion polymerization. Aided by a statistical software, d-optimal mixture design was used to vary the components (crosslinker, initiator, stabilizer, and macromonomers to obtain twenty nanoparticle formulations (PLLA-based nanoparticles and thirty formulations (poly-ɛ-caprolactone-based nanoparticles. Scheffe polynomial models were generated to predict particle size (nm, zeta potential, and yield (% as functions of the composition of the formulations. Simultaneous optimizations were carried out on the response variables. Solutions were returned from simultaneous optimization of the response variables for component combinations to (1 minimize nanoparticle size; (2 maximize the surface negative zeta potential; and (3 maximize percent yield to make the nanoparticle fabrication an economic proposition.

  7. Spatial uncoupling of biodegradation, soil respiration, and PAH concentration in a creosote contaminated soil.

    Science.gov (United States)

    Bengtsson, Göran; Törneman, Niklas; Yang, Xiuhong

    2010-09-01

    Hotspots and coldspots of concentration and biodegradation of polycyclic aromatic hydrocarbons (PAHs) marginally overlapped at the 0.5-100 m scale in a creosote contaminated soil in southern Sweden, suggesting that concentration and biodegradation had little spatial co-variation. Biodegradation was substantial and its spatial variability considerable and highly irregular, but it had no spatial autocorrelation. The soil concentration of PAHs explained only 20-30% of the variance of their biodegradation. Soil respiration was spatially autocorrelated. The spatial uncoupling between biodegradation and soil respiration seemed to be governed by the aging of PAHs in the soil, since biodegradation of added 13C phenanthrene covaried with both soil respiration and microbial biomass. The latter two were also correlated with high concentrations of phospholipid fatty acids (PLFAs) that are common in gram-negative bacteria. However, several of the hotspots of biodegradation coincided with hotspots for the distribution of a PLFA indicative of fungal biomass.

  8. Low voltage RF MEMS variable capacitor with linear C-V response

    KAUST Repository

    Elshurafa, Amro M.

    2012-07-23

    An RF MEMS variable capacitor, fabricated in the PolyMUMPS process and tuned electrostatically, possessing a linear capacitance-voltage response is reported. The measured quality factor of the device was 17 at 1GHz, while the tuning range was 1.2:1 and was achieved at an actuation DC voltage of 8V only. Further, the linear regression coefficient was 0.98. The variable capacitor was created such that it has both vertical and horizontal capacitances present. As the top suspended plate moves towards the bottom fixed plate, the vertical capacitance increases whereas the horizontal capacitance decreases simultaneously such that the sum of the two capacitances yields a linear capacitance-voltage relation. © 2012 The Institution of Engineering and Technology.

  9. Variability in sea ice cover and climate elicit sex specific responses in an Antarctic predator

    Science.gov (United States)

    Labrousse, Sara; Sallée, Jean-Baptiste; Fraser, Alexander D.; Massom, Rob A.; Reid, Phillip; Hobbs, William; Guinet, Christophe; Harcourt, Robert; McMahon, Clive; Authier, Matthieu; Bailleul, Frédéric; Hindell, Mark A.; Charrassin, Jean-Benoit

    2017-01-01

    Contrasting regional changes in Southern Ocean sea ice have occurred over the last 30 years with distinct regional effects on ecosystem structure and function. Quantifying how Antarctic predators respond to such changes provides the context for predicting how climate variability/change will affect these assemblages into the future. Over an 11-year time-series, we examine how inter-annual variability in sea ice concentration and advance affect the foraging behaviour of a top Antarctic predator, the southern elephant seal. Females foraged longer in pack ice in years with greatest sea ice concentration and earliest sea ice advance, while males foraged longer in polynyas in years of lowest sea ice concentration. There was a positive relationship between near-surface meridional wind anomalies and female foraging effort, but not for males. This study reveals the complexities of foraging responses to climate forcing by a poleward migratory predator through varying sea ice property and dynamic anomalies. PMID:28233791

  10. Complex response of white pines to past environmental variability increases understanding of future vulnerability.

    Directory of Open Access Journals (Sweden)

    Virginia Iglesias

    Full Text Available Ecological niche models predict plant responses to climate change by circumscribing species distributions within a multivariate environmental framework. Most projections based on modern bioclimatic correlations imply that high-elevation species are likely to be extirpated from their current ranges as a result of rising growing-season temperatures in the coming decades. Paleoecological data spanning the last 15,000 years from the Greater Yellowstone region describe the response of vegetation to past climate variability and suggest that white pines, a taxon of special concern in the region, have been surprisingly resilient to high summer temperature and fire activity in the past. Moreover, the fossil record suggests that winter conditions and biotic interactions have been critical limiting variables for high-elevation conifers in the past and will likely be so in the future. This long-term perspective offers insights on species responses to a broader range of climate and associated ecosystem changes than can be observed at present and should be part of resource management and conservation planning for the future.

  11. Climate variability slows evolutionary responses of Colias butterflies to recent climate change

    Science.gov (United States)

    Kingsolver, Joel G.; Buckley, Lauren B.

    2015-01-01

    How does recent climate warming and climate variability alter fitness, phenotypic selection and evolution in natural populations? We combine biophysical, demographic and evolutionary models with recent climate data to address this question for the subalpine and alpine butterfly, Colias meadii, in the southern Rocky Mountains. We focus on predicting patterns of selection and evolution for a key thermoregulatory trait, melanin (solar absorptivity) on the posterior ventral hindwings, which affects patterns of body temperature, flight activity, adult and egg survival, and reproductive success in Colias. Both mean annual summer temperatures and thermal variability within summers have increased during the past 60 years at subalpine and alpine sites. At the subalpine site, predicted directional selection on wing absorptivity has shifted from generally positive (favouring increased wing melanin) to generally negative during the past 60 years, but there is substantial variation among years in the predicted magnitude and direction of selection and the optimal absorptivity. The predicted magnitude of directional selection at the alpine site declined during the past 60 years and varies substantially among years, but selection has generally been positive at this site. Predicted evolutionary responses to mean climate warming at the subalpine site since 1980 is small, because of the variability in selection and asymmetry of the fitness function. At both sites, the predicted effects of adaptive evolution on mean population fitness are much smaller than the fluctuations in mean fitness due to climate variability among years. Our analyses suggest that variation in climate within and among years may strongly limit evolutionary responses of ectotherms to mean climate warming in these habitats. PMID:25631995

  12. Biodegradation of clofibric acid and identification of its metabolites

    Energy Technology Data Exchange (ETDEWEB)

    Salgado, R. [REQUIMTE/CQFB, Chemistry Department, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); ESTS-IPS, Escola Superior de Tecnologia de Setubal do Instituto Politecnico de Setubal, Rua Vale de Chaves, Campus do IPS, Estefanilha, 2910-761 Setubal (Portugal); Oehmen, A. [REQUIMTE/CQFB, Chemistry Department, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Carvalho, G. [REQUIMTE/CQFB, Chemistry Department, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Instituto de Biologia Experimental e Tecnologica (IBET), Av. da Republica (EAN), 2784-505 Oeiras (Portugal); Noronha, J.P. [REQUIMTE/CQFB, Chemistry Department, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Reis, M.A.M., E-mail: amr@fct.unl.pt [REQUIMTE/CQFB, Chemistry Department, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal)

    2012-11-30

    Graphical abstract: Metabolites produced during clofibric acid biodegradation. Highlights: Black-Right-Pointing-Pointer Clofibric acid is biodegradable. Black-Right-Pointing-Pointer Mainly heterotrophic bacteria degraded the clofibric acid. Black-Right-Pointing-Pointer Metabolites of clofibric acid biodegradation were identified. Black-Right-Pointing-Pointer The metabolic pathway of clofibric acid biodegradation is proposed. - Abstract: Clofibric acid (CLF) is the pharmaceutically active metabolite of lipid regulators clofibrate, etofibrate and etofyllinclofibrate, and it is considered both environmentally persistent and refractory. This work studied the biotransformation of CLF in aerobic sequencing batch reactors (SBRs) with mixed microbial cultures, monitoring the efficiency of biotransformation of CLF and the production of metabolites. The maximum removal achieved was 51% biodegradation (initial CLF concentration = 2 mg L{sup -1}), where adsorption and abiotic removal mechanisms were shown to be negligible, showing that CLF is indeed biodegradable. Tests showed that the observed CLF biodegradation was mainly carried out by heterotrophic bacteria. Three main metabolites were identified, including {alpha}-hydroxyisobutyric acid, lactic acid and 4-chlorophenol. The latter is known to exhibit higher toxicity than the parent compound, but it did not accumulate in the SBRs. {alpha}-Hydroxyisobutyric acid and lactic acid accumulated for a period, where nitrite accumulation may have been responsible for inhibiting their degradation. A metabolic pathway for the biodegradation of CLF is proposed in this study.

  13. Green and biodegradable electronics

    Directory of Open Access Journals (Sweden)

    Mihai Irimia-Vladu

    2012-07-01

    Full Text Available We live in a world where the lifetime of electronics is becoming shorter, now approaching an average of several months. This poses a growing ecological problem. This brief review will present some of the initial steps taken to address the issue of electronic waste with biodegradable organic electronic materials. Many organic materials have been shown to be biodegradable, safe, and nontoxic, including compounds of natural origin. Additionally, the unique features of such organic materials suggest they will be useful in biofunctional electronics; demonstrating functions that would be inaccessible for traditional inorganic compounds. Such materials may lead to fully biodegradable and even biocompatible/biometabolizable electronics for many low-cost applications. This review highlights recent progress in these classes of material, covering substrates and insulators, semiconductors, and finally conductors.

  14. Large-basin hydrological response to climate model outputs: uncertainty caused by the internal atmospheric variability

    Directory of Open Access Journals (Sweden)

    A. Gelfan

    2015-02-01

    Full Text Available An approach is proposed to assess hydrological simulation uncertainty originating from internal atmospheric variability. The latter is one of three major factors contributing to the uncertainty of simulated climate change projections (along with so-called "forcing" and "climate model" uncertainties. Importantly, the role of the internal atmospheric variability is the most visible over the spatial–temporal scales of water management in large river basins. The internal atmospheric variability is represented by large ensemble simulations (45 members with the ECHAM5 atmospheric general circulation model. The ensemble simulations are performed using identical prescribed lower boundary conditions (observed sea surface temperature, SST, and sea ice concentration, SIC, for 1979–2012 and constant external forcing parameters but different initial conditions of the atmosphere. The ensemble of the bias-corrected ECHAM5-outputs as well as ensemble averaged ECHAM5-output are used as the distributed input for ECOMAG and SWAP hydrological models. The corresponding ensembles of runoff hydrographs are calculated for two large rivers of the Arctic basin: the Lena and the Northern Dvina rivers. A number of runoff statistics including the mean and the SD of the annual, monthly and daily runoff, as well as the annual runoff trend are assessed. The uncertainties of runoff statistics caused by the internal atmospheric variability are estimated. It is found that the uncertainty of the mean and SD of the runoff has a distinguished seasonal dependence with maximum during the periods of spring-summer snowmelt and summer-autumn rainfall floods. A noticeable non-linearity of the hydrological models' response to the ensemble ECHAM5 output is found most strongly expressed for the Northern Dvine River basin. It is shown that the averaging over ensemble members effectively filters stochastic term related to internal atmospheric variability. The simulated trends are close to

  15. Continental-scale impacts of intra-seasonal rainfall variability on simulated ecosystem responses in Africa

    Directory of Open Access Journals (Sweden)

    K. Guan

    2014-05-01

    Full Text Available Climate change is expected to result in an increase of intra-seasonal rainfall variability, which has arisen from concurrent shifts in rainfall frequency, intensity and seasonality. Changes in intra-seasonal rainfall variability are likely to have important ecological impacts for terrestrial ecosystems, and quantifying these impacts across biomes and large climate gradients is required for a better prediction of ecosystem services and their responses to climate change. Here we use a synthetic weather generator and an advanced vegetation dynamic model (SEIB-DGVM to virtually conduct a series of "rainfall manipulation experiments" to study how changes in the intra-seasonal rainfall variability affect continent-scale ecosystem responses across Africa. We generated different rainfall scenarios with fixed total annual rainfall but shifts in: (i frequency vs. intensity, (ii seasonality vs. frequency, (iii intensity vs. seasonality. These scenarios were fed into the SEIB-DGVM to investigate changes in biome distributions and ecosystem productivity. We find a loss of ecosystem productivity with increased rainfall frequency and decreased intensity at very low rainfall regimes (−1 and low frequency (−1; beyond these very dry regimes, most ecosystems benefit from increasing frequency and decreasing intensity, except in the wet tropics (>1800 mm year−1 where radiation limitation prevents further productivity gains. This finding reconciles seemingly contradictory findings in previous field studies on the direction of rainfall frequency/intensity impacts on ecosystem productivity. We also find that changes in rainy season length can yield more dramatic ecosystem responses compared with similar percentage changes in rainfall frequency or intensity, with the largest impacts in semi-arid woodlands. This study demonstrates that not all rainfall regimes are ecologically equivalent, and that intra-seasonal rainfall characteristics play a significant role in

  16. Assessment of the Impact of Geomechanical Parameters Variability on Underground Excavations Stability Using Response Surface Method

    Science.gov (United States)

    Pytel, Witold; Świtoń, Joanna

    2013-03-01

    Recognition of properties of the rock mass surrounding a mineral deposit is particularly important for the mining operations at greater depths. Since the rock mass is usually not homogeneous, and its parameters have characteristics of randomness, underground workings safety issue should always be analysed taking into account the dispersion of the values of these parameters around their mean values. In order to assess the impact of geotechnical parameters uncertainty on the excavation stability one uses the appropriate statistical approach. In this paper, by analysing successive combinations of geomechanical parameters of the rock in the measured range, we examined the effect of their variability on risk of underground excavation instability using response surface method.

  17. Comparison between genomic predictions using daughter yield deviation and conventional estimated breeding value as response variables

    DEFF Research Database (Denmark)

    Guo, Gang; Lund, Mogens Sandø; Zhang, Y;

    2010-01-01

    This study compared genomic predictions using conventional estimated breeding values (EBV) and daughter yield deviations (DYD) as response variables based on simulated data. Eight scenarios were simulated in regard to heritability (0.05 and 0.30), number of daughters per sire (30, 100, and unequal......), the EBV and DYD approaches provided similar genomic estimated breeding value (GEBV) reliabilities, except for scenarios with unequal numbers of daughters and half of sires without genotype, for which the EBV approach was superior to the DYD approach (by 1.2 and 2.4%). Using a Bayesian mixture prior model...

  18. Latent Variable Selection for Multidimensional Item Response Theory Models via [Formula: see text] Regularization.

    Science.gov (United States)

    Sun, Jianan; Chen, Yunxiao; Liu, Jingchen; Ying, Zhiliang; Xin, Tao

    2016-12-01

    We develop a latent variable selection method for multidimensional item response theory models. The proposed method identifies latent traits probed by items of a multidimensional test. Its basic strategy is to impose an [Formula: see text] penalty term to the log-likelihood. The computation is carried out by the expectation-maximization algorithm combined with the coordinate descent algorithm. Simulation studies show that the resulting estimator provides an effective way in correctly identifying the latent structures. The method is applied to a real dataset involving the Eysenck Personality Questionnaire.

  19. Probabilistic models, learning algorithms, and response variability: sampling in cognitive development.

    Science.gov (United States)

    Bonawitz, Elizabeth; Denison, Stephanie; Griffiths, Thomas L; Gopnik, Alison

    2014-10-01

    Although probabilistic models of cognitive development have become increasingly prevalent, one challenge is to account for how children might cope with a potentially vast number of possible hypotheses. We propose that children might address this problem by 'sampling' hypotheses from a probability distribution. We discuss empirical results demonstrating signatures of sampling, which offer an explanation for the variability of children's responses. The sampling hypothesis provides an algorithmic account of how children might address computationally intractable problems and suggests a way to make sense of their 'noisy' behavior.

  20. Inter-Individual Variability in Human Response to Low-Dose Ionizing Radiation, Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Rocke, David [Univ. of California, Davis, CA (United States)

    2016-08-01

    In order to investigate inter-individual variability in response to low-dose ionizing radiation, we are working with three models, 1) in-vivo irradiated human skin, for which we have a realistic model, but with few subjects, all from a previous project, 2) ex-vivo irradiated human skin, for which we also have a realistic model, though with the limitations involved in keeping skin pieces alive in media, and 3) MatTek EpiDermFT skin plugs, which provides a more realistic model than cell lines, which is more controllable than human samples.

  1. Editorial: Biodegradable Materials

    Directory of Open Access Journals (Sweden)

    Carl Schaschke

    2014-11-01

    Full Text Available This Special Issue “Biodegradable Materials” features research and review papers concerning recent advances on the development, synthesis, testing and characterisation of biomaterials. These biomaterials, derived from natural and renewable sources, offer a potential alternative to existing non-biodegradable materials with application to the food and biomedical industries amongst many others. In this Special Issue, the work is expanded to include the combined use of fillers that can enhance the properties of biomaterials prepared as films. The future application of these biomaterials could have an impact not only at the economic level, but also for the improvement of the environment.

  2. Development and Validation of Culture-Specific Variable Response Inconsistency and True Response Inconsistency Scales for Use with the Korean MMPI-2

    Science.gov (United States)

    Ketterer, Holly L.; Han, Kyunghee; Hur, Jaehong; Moon, Kyungjoo

    2010-01-01

    In response to the concern that Minnesota Multiphasic Personality Inventory-2 (MMPI-2; J. N. Butcher, W. Dahlstrom, J. R. Graham, A. Tellegen, & B. Kaemmer, 1989; J. N. Butcher et al., 2001) Variable Response Inconsistency (VRIN) and True Response Inconsistency (TRIN) score invalidity criteria recommended for use with American samples results…

  3. Wintertime atmospheric response to Atlantic multidecadal variability: effect of stratospheric representation and ocean-atmosphere coupling

    Science.gov (United States)

    Peings, Yannick; Magnusdottir, Gudrun

    2016-08-01

    The impact of the Atlantic multidecadal variability (AMV) on the wintertime atmosphere circulation is investigated using three different configurations of the Community Atmospheric Model version 5 (CAM5). Realistic SST and sea ice anomalies associated with the AMV in observations are prescribed in CAM5 (low-top model) and WACCM5 (high-top model) to assess the dependence of the results on the representation of the stratosphere. In a third experiment, the role of ocean-atmosphere feedback is investigated by coupling CAM5 to a slab-ocean model in which the AMV forcing is prescribed through oceanic heat flux anomalies. The three experiments give consistent results concerning the response of the NAO in winter, with a negative NAO signal in response to a warming of the North Atlantic ocean. This response is found in early winter when the high-top model is used, and in late winter with the low-top model. With the slab-ocean, the negative NAO response is more persistent in winter and shifted eastward over the continent due to the damping of the atmospheric response over the North Atlantic ocean. Additional experiments suggest that both tropical and extratropical SST anomalies are needed to obtain a significant modulation of the NAO, with small influence of sea ice anomalies. Warm tropical SST anomalies induce a northward shift of the ITCZ and a Rossby-wave response that is reinforced in the mid-latitudes by the extratropical SST anomalies through eddy-mean flow interactions. This modeling study supports that the positive phase of the AMV promotes the negative NAO in winter, while illustrating the impacts of the stratosphere and of the ocean-atmosphere feedbacks in the spatial pattern and timing of this response.

  4. [Predictive response variables to recombinant human erythropoietin treatment in patients with anemia and cancer].

    Science.gov (United States)

    Lastiri, José M; Specterman, Sergio R; Rendo, Pablo; Pallotta, María G; Varela, Mirta S; Goldstein, Sofía

    2002-01-01

    The use of human recombinant erythropoietin (rHuEpo) has been approved by the Food and Drug Administration (FDA) in patients with anemia and cancer. Although good results have been obtained, it is too expensive to permit its use massively. For the purpose of evaluating the therapeutic effect of rHuEpo, including toxicity, predictive response variables and quality of life parameters, a prospective trial was carried out in patients with anemia and cancer. Hematimetric parameters, ferritin, Epo, cytokines, transfusions and quality of life were registered. A total of 36 patients were treated in the protocol (34 were evaluable): 16 men and 20 women, with a medium age 56.4 years; 27 patients were treated with chemotherapy (16 with cisplatinum); 15 patients presented medullar infiltration. In 73.5% patients an increase in the level of hemoglobin was registered, and in 64.7% its normalisation was attained. Transfusional requirements were reduced by 50%. The hemoglobin increase greater than 0.5 g/dl at the second week of treatment was the most significant variable of early response. Patients treated with cisplatinum, seric ferritin lower than 1,100 ng/dl and those without medullar tumoral infiltration responded best. Serum Epo, cytokines (IL-1, IL-6 and TNF) and reticulocyte count at the second week did not correlate with response. Quality of life parameters were better in patients with good response to rHuEpo. It can be concluded that good results in the treatment of patients with anemia and cancer are obtained with rHuEpo.

  5. Ecosystem responses to recent oceanographic variability in high-latitude Northern Hemisphere ecosystems

    Science.gov (United States)

    Mueter, Franz J.; Broms, Cecilie; Drinkwater, Kenneth F.; Friedland, Kevin D.; Hare, Jonathan A.; Hunt, George L., Jr.; Melle, Webjørn; Taylor, Maureen

    2009-04-01

    As part of the international MENU collaboration, we compared and contrasted ecosystem responses to climate-forced oceanographic variability across several high latitude regions of the North Pacific (Eastern Bering Sea (EBS) and Gulf of Alaska (GOA)) and North Atlantic Oceans (Gulf of Maine/Georges Bank (GOM/GB) and the Norwegian/Barents Seas (NOR/BAR)). Differences in the nitrate content of deep source waters and incoming solar radiation largely explain differences in average primary productivity among these ecosystems. We compared trends in productivity and abundance at various trophic levels and their relationships with sea-surface temperature. Annual net primary production generally increases with annual mean sea-surface temperature between systems and within the EBS, BAR, and GOM/GB. Zooplankton biomass appears to be controlled by both top-down (predation by fish) and bottom-up forcing (advection, SST) in the BAR and NOR regions. In contrast, zooplankton in the GOM/GB region showed no evidence of top-down forcing but appeared to control production of major fish populations through bottom-up processes that are independent of temperature variability. Recruitment of several fish stocks is significantly and positively correlated with temperature in the EBS and BAR, but cod and pollock recruitment in the EBS has been negatively correlated with temperature since the 1977 shift to generally warmer conditions. In each of the ecosystems, fish species showed a general poleward movement in response to warming. In addition, the distribution of groundfish in the EBS has shown a more complex, non-linear response to warming resulting from internal community dynamics. Responses to recent warming differ across systems and appear to be more direct and more pronounced in the higher latitude systems where food webs and trophic interactions are simpler and where both zooplankton and fish species are often limited by cold temperatures.

  6. Influence of soil contamination with PAH on microbial community dynamics and expression level of genes responsible for biodegradation of PAH and production of rhamnolipids.

    Science.gov (United States)

    Szczepaniak, Zuzanna; Czarny, Jakub; Staninska-Pięta, Justyna; Lisiecki, Piotr; Zgoła-Grześkowiak, Agnieszka; Cyplik, Paweł; Chrzanowski, Łukasz; Wolko, Łukasz; Marecik, Roman; Juzwa, Wojciech; Glazar, Katarzyna; Piotrowska-Cyplik, Agnieszka

    2016-11-01

    The aim of this study was to evaluate the effect of bioaugmentation and addition of rhamnolipids on the biodegradation of PAHs in artificially contaminated soil, expression of genes crucial for the biodegradation process (PAHRHDαGN, PAHRHDαGP), and the synthesis of rhamnolipids as well as population changes in the soil bacterial metabiome. The positive effect of bioaugmentation and addition of rhamnolipids on the bioremediation of the majority of PAHs was confirmed during the early stages of treatment, especially in case of the most structurally complicated compounds. The results of metagenomic analysis indicated that the initial changes in the soil metabiome caused by bioaugmentation diminished after 3 months and that the community structure in treated soil was similar to control. The survival period of bacteria introduced into the soil via bioaugmentation reached a maximum of 3 months. The increased expression of genes observed after addition of PAH into the soil also returned to the initial conditions after 3 months.

  7. On the response of the Aegean Sea to climatic variability: a review

    Science.gov (United States)

    Zervakis, V.; Georgopoulos, D.; Karageorgis, A. P.; Theocharis, A.

    2004-11-01

    The Aegean Sea is a region of special interest for the Mediterranean oceanographic community, as one of the dense-water formation sites of the Mediterranean, driving its thermohaline circulation. Early oceanographic literature exhibits significantly varying opinions regarding the role of the Aegean as a contributor to the water masses of the eastern Mediterranean. The higher temporal and spatial resolution studies that followed the introduction of Conductivity-Temperature-Depth (CTD) profilers in the 1980s, revealed that the various scenarios were within the interannual variability of dense water formation in the region. A peak in this variability was the appearance of the Eastern Mediterranean Transient event in the early 1990s. This phenomenon showed that the Aegean Sea has the potential to function as a source of dense water for the eastern Mediterranean; however, it takes over this role only sporadically, depending on the meteorological conditions over the eastern Mediterranean and, possibly, central/eastern Europe. The North Atlantic oscillation appears to be a contributor to this bimodal behaviour. Palaeoceanographic information has confirmed the large sensitivity of the Aegean Sea to climatic variability. Based on the available information, possible scenarios are examined for the response of the Aegean to the current climatic trends.

  8. A note on monotone likelihood ratio of the total score variable in unidimensional item response theory.

    Science.gov (United States)

    Unlü, Ali

    2008-05-01

    This note provides a direct, elementary proof of the fundamental result on monotone likelihood ratio of the total score variable in unidimensional item response theory (IRT). This result is very important for practical measurement in IRT, because it justifies the use of the total score variable to order participants on the latent trait. The proof relies on a basic inequality for elementary symmetric functions which is proved by means of few purely algebraic, straightforward transformations. In particular, flaws in a proof of this result by Huynh [(1994). A new proof for monotone likelihood ratio for the sum of independent Bernoulli random variables. Psychometrika, 59, 77-79] are pointed out and corrected, and a natural generalization of the fundamental result to non-linear (quasi-ordered) latent trait spaces is presented. This may be useful for multidimensional IRT or knowledge space theory, in which the latent 'ability' spaces are partially ordered with respect to, for instance, coordinate-wise vector-ordering or set-inclusion, respectively.

  9. Variable selection for distribution-free models for longitudinal zero-inflated count responses.

    Science.gov (United States)

    Chen, Tian; Wu, Pan; Tang, Wan; Zhang, Hui; Feng, Changyong; Kowalski, Jeanne; Tu, Xin M

    2016-07-20

    Zero-inflated count outcomes arise quite often in research and practice. Parametric models such as the zero-inflated Poisson and zero-inflated negative binomial are widely used to model such responses. Like most parametric models, they are quite sensitive to departures from assumed distributions. Recently, new approaches have been proposed to provide distribution-free, or semi-parametric, alternatives. These methods extend the generalized estimating equations to provide robust inference for population mixtures defined by zero-inflated count outcomes. In this paper, we propose methods to extend smoothly clipped absolute deviation (SCAD)-based variable selection methods to these new models. Variable selection has been gaining popularity in modern clinical research studies, as determining differential treatment effects of interventions for different subgroups has become the norm, rather the exception, in the era of patent-centered outcome research. Such moderation analysis in general creates many explanatory variables in regression analysis, and the advantages of SCAD-based methods over their traditional counterparts render them a great choice for addressing this important and timely issues in clinical research. We illustrate the proposed approach with both simulated and real study data. Copyright © 2016 John Wiley & Sons, Ltd.

  10. Seismic Response Control Of Structures Using Semi-Active and Passive Variable Stiffness Devices

    Science.gov (United States)

    Salem, Mohamed M. A.

    Controllable devices such as Magneto-Rheological Fluid Dampers, Electro-Rheological Dampers, and controllable friction devices have been studied extensively with limited implementation in real structures. Such devices have shown great potential in reducing seismic demands, either as smart base isolation systems, or as smart devices for multistory structures. Although variable stiffness devices can be used for seismic control of structures, the vast majority of research effort has been given to the control of damping. The primary focus of this dissertation is to evaluate the seismic control of structures using semi-active and passive variable stiffness characteristics. Smart base isolation systems employing variable stiffness devices have been studied, and two semi-active control strategies are proposed. The control algorithms were designed to reduce the superstructure and base accelerations of seismically isolated structures subject to near-fault and far-field ground motions. Computational simulations of the proposed control algorithms on the benchmark structure have shown that excessive base displacements associated with the near-fault ground motions may be better mitigated with the use of variable stiffness devices. However, the device properties must be controllable to produce a wide range of stiffness changes for an effective control of the base displacements. The potential of controllable stiffness devices in limiting the base displacement due to near-fault excitation without compromising the performance of conventionally isolated structures, is illustrated. The application of passive variable stiffness devices for seismic response mitigation of multistory structures is also investigated. A stiffening bracing system (SBS) is proposed to replace the conventional bracing systems of braced frames. An optimization process for the SBS parameters has been developed. The main objective of the design process is to maintain a uniform inter-story drift angle over the

  11. Assessing conservation relevance of organism-environment relations using predicted changes in response variables

    Science.gov (United States)

    Gutzwiller, Kevin J.; Barrow, Wylie C.; White, Joseph D.; Johnson-Randall, Lori; Cade, Brian S.; Zygo, Lisa M.

    2010-01-01

    1. Organism–environment models are used widely in conservation. The degree to which they are useful for informing conservation decisions – the conservation relevance of these relations – is important because lack of relevance may lead to misapplication of scarce conservation resources or failure to resolve important conservation dilemmas. Even when models perform well based on model fit and predictive ability, conservation relevance of associations may not be clear without also knowing the magnitude and variability of predicted changes in response variables. 2. We introduce a method for evaluating the conservation relevance of organism–environment relations that employs confidence intervals for predicted changes in response variables. The confidence intervals are compared to a preselected magnitude of change that marks a threshold (trigger) for conservation action. To demonstrate the approach, we used a case study from the Chihuahuan Desert involving relations between avian richness and broad-scale patterns of shrubland. We considered relations for three winters and two spatial extents (1- and 2-km-radius areas) and compared predicted changes in richness to three thresholds (10%, 20% and 30% change). For each threshold, we examined 48 relations. 3. The method identified seven, four and zero conservation-relevant changes in mean richness for the 10%, 20% and 30% thresholds respectively. These changes were associated with major (20%) changes in shrubland cover, mean patch size, the coefficient of variation for patch size, or edge density but not with major changes in shrubland patch density. The relative rarity of conservation-relevant changes indicated that, overall, the relations had little practical value for informing conservation decisions about avian richness. 4. The approach we illustrate is appropriate for various response and predictor variables measured at any temporal or spatial scale. The method is broadly applicable across ecological

  12. Experimental Investigation and Optimization of Response Variables in WEDM of Inconel - 718

    Science.gov (United States)

    Karidkar, S. S.; Dabade, U. A.

    2016-02-01

    Effective utilisation of Wire Electrical Discharge Machining (WEDM) technology is challenge for modern manufacturing industries. Day by day new materials with high strengths and capabilities are being developed to fulfil the customers need. Inconel - 718 is similar kind of material which is extensively used in aerospace applications, such as gas turbine, rocket motors, and spacecraft as well as in nuclear reactors and pumps etc. This paper deals with the experimental investigation of optimal machining parameters in WEDM for Surface Roughness, Kerf Width and Dimensional Deviation using DoE such as Taguchi methodology, L9 orthogonal array. By keeping peak current constant at 70 A, the effect of other process parameters on above response variables were analysed. Obtained experimental results were statistically analysed using Minitab-16 software. Analysis of Variance (ANOVA) shows pulse on time as the most influential parameter followed by wire tension whereas spark gap set voltage is observed to be non-influencing parameter. Multi-objective optimization technique, Grey Relational Analysis (GRA), shows optimal machining parameters such as pulse on time 108 Machine unit, spark gap set voltage 50 V and wire tension 12 gm for optimal response variables considered for the experimental analysis.

  13. Transient aeroelastic responses and flutter analysis of a variable-span wing during the morphing process

    Institute of Scientific and Technical Information of China (English)

    Huang Ren; Qiu Zhiping

    2013-01-01

    To investigate the transient aeroelastic responses and flutter characteristics of a variable-span wing during the morphing process, a novel first-order state-space aeroelastic model is pro-posed. The time-varying structural model of the morphing wing is established based on the Euler-Bernoulli beam theory with time-dependent boundary conditions. A nondimensionalization method is used to translate the time-dependent boundary conditions to be time-independent. The time-domain aerodynamic forces are calculated by the reduced-order unsteady vortex lattice method. The morphing parameters, i.e., wing span length and morphing speed, are of particular interest for understanding the fundamental aeroelastic behavior of variable-span wings. A test case is proposed and numerical results indicate that the flutter characteristics are sensitive to both of the two morphing parameters. It could be noticed that the aeroelastic characteristics during the wing extracting process are more serious than those during the extending process at the same morphing speed by transient aeroelastic response analysis. In addition, a faster morphing process can get bet-ter aeroelastic performance while the mechanism comlexity will arise.

  14. Manipulation of heart rate variability can modify response to anger-inducing stimuli.

    Science.gov (United States)

    Francis, Heather M; Penglis, Kathryn M; McDonald, Skye

    2016-10-01

    Research suggests that heart rate variability (HRV) is a physiological indicator of the flexibility of the autonomic nervous system and can provide an objective measure of an individual's ability to appropriately match emotional responses to environmental demands. The present study investigated whether angry response to emotional stimuli was related to HRV, and whether manipulation of HRV using biofeedback could change the anger response in a healthy adult population. Fifty-eight participants received HRV biofeedback (n = 29) or an active control condition (n = 29). HRV measures included standard deviation of normal-to-normal intervals (SDNN), low-frequency (LF) and high-frequency (HF) power, and was recorded across three sessions: baseline, training, and anger induction. The anger induction procedure resulted in increased subjective experience of anger, as well as physiological changes. The biofeedback group had higher HRV than active controls both during the training session (SDNN and LF HRV) and during anger induction (LF HRV). HRV during anger induction was significantly associated with self-reported emotional response for participants receiving biofeedback but not for active controls. Results provide support for HRV as an index of emotion regulation, specifically anger. Further research is needed to determine whether long-term HRV biofeedback can have a lasting effect on managing anger.

  15. Frequency Domain Analysis for Assessing Fluid Responsiveness by Using Instantaneous Pulse Rate Variability

    Directory of Open Access Journals (Sweden)

    Pei-Chen Lin

    2016-02-01

    Full Text Available In the ICU, fluid therapy is conventional strategy for the patient in shock. However, only half of ICU patients have well-responses to fluid therapy, and fluid loading in non-responsive patient delays definitive therapy. Prediction of fluid responsiveness (FR has become intense topic in clinic. Most of conventional FR prediction method based on time domain analysis, and it is limited ability to indicate FR. This study proposed a method which predicts FR based on frequency domain analysis, named instantaneous pulse rate variability (iPRV. iPRV provides a new indication in very high frequency (VHF range (0.4-0.8Hz of spectrum for peripheral responses. Twenty six healthy subjects participated this study and photoplethysmography signal was recorded in supine baseline, during head-up tilt (HUT, and passive leg raising (PLR, which induces variation of venous return and helps for quantitative assessment of FR individually. The result showed the spectral power of VHF decreased during HUT (573.96±756.36 ms2 in baseline; 348.00±434.92 ms2 in HUT and increased during PLR (573.96±756.36 ms2 in baseline; 718.92±973.70 ms2 in PLR, which present the compensated regulation of venous return and FR. This study provides an effective indicator for assessing FR in frequency domain and has potential to be a reliable system in ICU.

  16. Statistical correlation of fractional oscillator response by complex spectral moments and state variable expansion

    Science.gov (United States)

    Pinnola, Francesco Paolo

    2016-10-01

    The statistical characterization of the oscillator response with non-integer order damping under Gaussian noise represents an important challenge in the modern stochastic mechanics. In fact, this kind of problem appears in several issues of different type (wave propagation in viscoelastic media, Brownian motion, fluid dynamics, RLC circuit, etc.). The aim of this paper is to provide a stochastic characterization of the stationary response of linear fractional oscillator forced by normal white noise. In particular, this paper shows a new method to obtain the correlation function by exact complex spectral moments. These complex quantities contain all the information to describe the random processes but in the considered case their analytical evaluation needs some mathematical manipulations. For this reason such complex spectral moment characterization is used in conjunction with a fractional-order state variable analysis. This kind of analysis permits to find the exact expression of complex spectral moments, and the correlation function by using the Mellin transform. Moreover, the proposed approach provides an analytical expression of the response variance of the fractional oscillator. Capability and efficiency of the present method are shown in the numerical examples in which correlation and variance of fractional oscillator response are found and compared with those obtained by Monte Carlo simulations.

  17. Factors responsible for mortality variation in the United States: A latent variable analysis

    Directory of Open Access Journals (Sweden)

    Christopher Tencza

    2014-07-01

    Full Text Available Background: Factors including smoking, drinking, substance abuse, obesity, and health care have all been shown to affect health and longevity. The relative importance of each of these factors is disputed in the literature, and has been assessed through a number of methods. Objective: This paper uses a novel approach to identify factors responsible for interstate mortality variation. It identifies factors through their imprint on mortality patterns and can therefore identify factors that are difficult or impossible to measure directly, such as sensitive health behaviors. Methods: The analysis calculates age-standardized death rates by cause of death from 2000-2009 for white men and women separately. Only premature deaths between ages 20-64 are included. Latent variables responsible for mortality variation are then identified through a factor analysis conducted on a death-rate-by-state matrix. These unobserved latent variables are inferred from observed mortality data and interpreted based on their correlations with individual causes of death. Results: Smoking and obesity, substance abuse, and rural/urban residence are the three factors that make the largest contributions to state-level mortality variation among males. The same factors are at work for women but are less vividly revealed. The identification of factors is supported by a review of epidemiologic studies and strengthened by correlations with observable behavioral variables. Results are not sensitive to the choice of factor-analytic method used. Conclusions: The majority of interstate variation in mortality among white working-age adults in the United States is associated with a combination of smoking and obesity, substance abuse and rural/urban residence.

  18. Forced response and internal variability of summer climate over western North America

    Science.gov (United States)

    Kamae, Youichi; Shiogama, Hideo; Imada, Yukiko; Mori, Masato; Arakawa, Osamu; Mizuta, Ryo; Yoshida, Kohei; Takahashi, Chiharu; Arai, Miki; Ishii, Masayoshi; Watanabe, Masahiro; Kimoto, Masahide; Xie, Shang-Ping; Ueda, Hiroaki

    2016-09-01

    Over the past decade, anomalously hot summers and persistent droughts frequented over the western United States (wUS), the condition similar to the 1950s and 1960s. While atmospheric internal variability is important for mid-latitude interannual climate variability, it has been suggested that anthropogenic external forcing and multidecadal modes of variability in sea surface temperature, namely, the Pacific Decadal Oscillation (PDO) and Atlantic Multidecadal Oscillation (AMO), also affect the occurrence of droughts and hot summers. In this study, 100-member ensemble simulations for 1951-2010 by an atmospheric general circulation model were used to explore relative contributions of anthropogenic warming, atmospheric internal variability, and atmospheric response to PDO and AMO to the decadal anomalies over the wUS. By comparing historical and sensitivity simulations driven by observed sea surface temperature, sea ice, historical forcing agents, and non-warming counterfactual climate forcing, we found that large portions of recent increases in mean temperature and frequency of hot summers (66 and 82 %) over the wUS can be attributed to the anthropogenic global warming. In contrast, multidecadal change in the wUS precipitation is explained by a combination of the negative PDO and the positive AMO after the 2000s. Diagnostics using a linear baroclinic model indicate that AMO- and PDO-related diabatic heating anomalies over the tropics contribute to the anomalous atmospheric circulation associated with the droughts and hot summers over wUS on multidecadal timescale. Those anomalies are not robust during the periods when PDO and AMO are in phase. The prolonged PDO-AMO antiphase period since the late twentieth century resulted in the substantial component of multidecadal anomalies in temperature and precipitation over the wUS.

  19. Biodegradable Materials for Nonwovens

    Science.gov (United States)

    Demand for nonwovens is increasing globally, particularly in the disposable products area. As the consumption of nonwoven products with short life increases, the burden on waste disposal also rises. In this context, biodegradable nonwovens become more important today and for the future. Several new ...

  20. Grey water biodegradability

    NARCIS (Netherlands)

    Abu Ghunmi, L.; Zeeman, G.; Fayyad, M.; Van Lier, J.B.

    2010-01-01

    Knowing the biodegradability characteristics of grey water constituents is imperative for a proper design and operation of a biological treatment system of grey water. This study characterizes the different COD fractions of dormitory grey water and investigates the effect of applying different condi

  1. Grey water biodegradability

    NARCIS (Netherlands)

    Abu Ghunmi, L.; Zeeman, G.; Fayyad, M.; Lier, van J.B.

    2011-01-01

    Knowing the biodegradability characteristics of grey water constituents is imperative for a proper design and operation of a biological treatment system of grey water. This study characterizes the different COD fractions of dormitory grey water and investigates the effect of applying different condi

  2. Increased Intrasubject Variability in Response Time in Youths with Bipolar Disorder and At-Risk Family Members

    Science.gov (United States)

    Brotman, Melissa A.; Rooney, Melissa H.; Skup, Martha; Pine, Daniel S.; Leibenluft, Ellen

    2009-01-01

    Intrasubject variability in response time (ISV-RT) was higher in youths with bipolar disorder (BD) and those with first-degree relatives with BD compared to youths without BD. ISV-RT may be a risk marker for BD.

  3. A Method for Analyzing the Dynamic Response of a Structural System with Variable Mass, Damping and Stiffness

    Directory of Open Access Journals (Sweden)

    Mike D.R. Zhang

    2001-01-01

    Full Text Available In this paper, a method for analyzing the dynamic response of a structural system with variable mass, damping and stiffness is first presented. The dynamic equations of the structural system with variable mass and stiffness are derived according to the whole working process of a bridge bucket unloader. At the end of the paper, an engineering numerical example is given.

  4. Going for distance and going for speed: effort and optical variables shape information for distance perception from observation to response.

    Science.gov (United States)

    Hajnal, Alen; Bunch, David A; Kelty-Stephen, Damian G

    2014-05-01

    Visually guided distance perception reflects a relationship of geometrical optical variables with the effort required when traversing the distance. We probed how the representations encoding optical variables might define this relationship. Participants visually judged distances on sloped surfaces and reproduced these distances over flat terrain by walking while blindfolded. We examined the responses for the effects of optical variables (i.e., angular declinations from eye height) and tested whether four measures of trial-by-trial effort moderated the use of the represented optical variables. We predicted that observation time and response speed relative to the observed distance would accentuate the effects of encoded optical variables, and that response time and response speed relative to the traversed distance would reduce the effects of those variables. The results confirmed all of the effects except those of observation time. Given the benefits of longer study for strengthening a memory trace, the failure of observation time to predict the use of optical variables raises questions about the representational encoding of visual traces for distance perception. Relationships among optical variables and other effort measures implicate the interaction of processes across multiple time scales, as in cascade dynamics. Cascade dynamics may provide new directions for accounts of visually guided distance perception.

  5. Genetic control of the variable innate immune response to asymptomatic bacteriuria.

    Directory of Open Access Journals (Sweden)

    Jenny Grönberg-Hernández

    Full Text Available The severity of urinary tract infection (UTI reflects the quality and magnitude of the host response. While strong local and systemic innate immune activation occurs in patients with acute pyelonephritis, the response to asymptomatic bacteriuria (ABU is low. The immune response repertoire in ABU has not been characterized, due to the inherent problem to distinguish bacterial differences from host-determined variation. In this study, we investigated the host response to ABU and genetic variants affecting innate immune signaling and UTI susceptibility. Patients were subjected to therapeutic urinary tract inoculation with E. coli 83972 to ensure that they were exposed to the same E. coli strain. The innate immune response repertoire was characterized in urine samples, collected from each patient before and after inoculation with bacteria or PBS, if during the placebo arm of the study. Long-term E. coli 83972 ABU was established in 23 participants, who were followed for up to twelve months and the innate immune response was quantified in 233 urine samples. Neutrophil numbers increased in all but two patients and in an extended urine cytokine/chemokine analysis (31 proteins, the chemoattractants IL-8 and GRO-α, RANTES, Eotaxin-1 and MCP-1, the T cell chemoattractant and antibacterial peptide IP-10, inflammatory regulators IL-1-α and sIL-1RA and the T lymphocyte/dendritic cell product sIL-2Rα were detected and variably increased, compared to sterile samples. IL-6, which is associated with symptomatic UTI, remained low and numerous specific immune mediators were not detected. The patients were also genotyped for UTI-associated IRF3 and TLR4 promoter polymorphisms. Patients with ABU associated TLR4 polymorphisms had low neutrophil numbers, IL-6, IP-10, MCP-1 and sIL-2Rα concentrations. Patients with the ABU-associated IRF3 genotype had lower neutrophils, IL-6 and MCP-1 responses than the remaining group. The results suggest that the host

  6. Optimization of Process Variables for Insulation Coating of Conductive Particles by Response Surface Methodology

    Energy Technology Data Exchange (ETDEWEB)

    Sim, Chol-Ho [Sangji University, Wonju (Korea, Republic of)

    2016-02-15

    The powder core, conventionally fabricated from iron particles coated with insulator, showed large eddy current loss under high frequency, because of small specific resistance. To overcome the eddy current loss, the increase in the specific resistance of powder cores was needed. In this study, copper oxide coating onto electrically conductive iron particles was performed using a planetary ball mill to increase the specific resistance. Coating factors were optimized by the Response surface methodology. The independent variables were the CuO mass fraction, mill revolution number, coating time, ball size, ball mass and sample mass. The response variable was the specific resistance. The optimization of six factors by the fractional factorial design indicated that CuO mass fraction, mill revolution number, and coating time were the key factors. The levels of these three factors were selected by the three-factors full factorial design and steepest ascent method. The steepest ascent method was used to approach the optimum range for maximum specific resistance. The Box-Behnken design was finally used to analyze the response surfaces of the screened factors for further optimization. The results of the Box-Behnken design showed that the CuO mass fraction and mill revolution number were the main factors affecting the efficiency of coating process. As the CuO mass fraction increased, the specific resistance increased. In contrast, the specific resistance increased with decreasing mill revolution number. The process optimization results revealed a high agreement between the experimental and the predicted data (Adj-R2=0.944). The optimized CuO mass fraction, mill revolution number, and coating time were 0.4, 200 rpm, and 15 min, respectively. The measured value of the specific resistance of the coated pellet under the optimized conditions of the maximum specific resistance was 530 kΩ·cm.

  7. Continental-scale impacts of intra-seasonal rainfall variability on simulated ecosystem responses in Africa

    Science.gov (United States)

    Guan, K.; Good, S. P.; Caylor, K. K.; Sato, H.; Wood, E. F.; Li, H.

    2014-12-01

    Climate change is expected to modify intra-seasonal rainfall variability, arising from shifts in rainfall frequency, intensity and seasonality. These intra-seasonal changes are likely to have important ecological impacts on terrestrial ecosystems. Yet, quantifying these impacts across biomes and large climate gradients is largely missing. This gap hinders our ability to better predict ecosystem services and their responses to climate change, especially for arid and semi-arid ecosystems. Here we use a synthetic weather generator and an independently validated vegetation dynamic model (SEIB-Dynamic Global Vegetation Model, DGVM) to virtually conduct a series of "rainfall manipulation experiments" to study how changes in the intra-seasonal rainfall variability affect continent-scale ecosystem responses across Africa. We generate different rainfall scenarios with fixed total annual rainfall but shifts in (i) frequency vs. intensity, (ii) rainy season length vs. frequency, (iii) intensity vs. rainy season length. These scenarios are fed into SEIB-DGVM to investigate changes in biome distributions and ecosystem productivity. We find a loss of ecosystem productivity with increased rainfall frequency and decreased intensity at very low rainfall regimes (year-1) and low frequency (benefit from increased frequency and decreased intensity, except in the wet tropics (>1800 mm year-1) where radiation limitation prevents further productivity gains. This result reconciles seemingly contradictory findings in previous field studies on the impact of rainfall frequency/intensity on ecosystem productivity. We also find that changes in rainy season length can yield more dramatic ecosystem responses compared with similar percentage changes in rainfall frequency or intensity, with the largest impacts in semi-arid woodlands. This study demonstrates that intra-seasonal rainfall characteristics play a significant role in influencing ecosystem function and structure through controls on

  8. Monsoonal variability in abiotic parameters in coastal waters off Trivandrum evokes press and pulse response in biotic variables

    Digital Repository Service at National Institute of Oceanography (India)

    Subina, N.S.; Bhosle, S.; Nair, S.; Lokabharathi, P.A.

    Trivandrum Coast experiences coastal upwelling during south west monsoon, which is accompanied by abiotic changes in physio-chemical parameters. The resultant biotic responses could range from an instantaneous pulse to a sustained press reaction...

  9. Hydrological response to changing climate conditions: Spatial streamflow variability in the boreal region

    Science.gov (United States)

    Teutschbein, Claudia; Grabs, Thomas; Karlsen, Reinert H.; Laudon, Hjalmar; Bishop, Kevin

    2016-04-01

    It has long been recognized that streamflow-generating processes are not only dependent on climatic conditions, but also affected by physical catchment properties such as topography, geology, soils and land cover. We hypothesize that these landscape characteristics do not only lead to highly variable hydrologic behavior of rather similar catchments under the same stationary climate conditions (Karlsen et al., 2014), but that they also play a fundamental role for the sensitivity of a catchment to a changing climate (Teutschbein et al., 2015). A multi-model ensemble based on 15 regional climate models was combined with a multi-catchment approach to explore the hydrologic sensitivity of 14 partially nested and rather similar catchments in Northern Sweden to changing climate conditions and the importance of small-scale spatial variability. Current (1981-2010) and future (2061-2090) streamflow was simulated with the HBV model. As expected, projected increases in temperature and precipitation resulted in increased total available streamflow, with lower spring and summer flows, but substantially higher winter streamflow. Furthermore, significant changes in flow durations with lower chances of both high and low flows can be expected in boreal Sweden in the future. This overall trend in projected streamflow pattern changes was comparable among the analyzed catchments while the magnitude of change differed considerably. This suggests that catchments belonging to the same region can show distinctly different degrees of hydrological responses to the same external climate change signal. We reason that differences in spatially distributed physical catchment properties at smaller scales are not only of great importance for current streamflow behavior, but also play a major role as first-order control for the sensitivity of catchments to changing climate conditions. References Karlsen, R.H., T. Grabs, K. Bishop, H. Laudon, and J. Seibert (2014). Landscape controls on

  10. Neuronal growth and differentiation on biodegradable membranes.

    Science.gov (United States)

    Morelli, Sabrina; Piscioneri, Antonella; Messina, Antonietta; Salerno, Simona; Al-Fageeh, Mohamed B; Drioli, Enrico; De Bartolo, Loredana

    2015-02-01

    Semipermeable polymeric membranes with appropriate morphological, physicochemical and transport properties are relevant to inducing neural regeneration. We developed novel biodegradable membranes to support neuronal differentiation. In particular, we developed chitosan, polycaprolactone and polyurethane flat membranes and a biosynthetic blend between polycaprolactone and polyurethane by phase-inversion techniques. The biodegradable membranes were characterized in order to evaluate their morphological, physicochemical, mechanical and degradation properties. We investigated the efficacy of these different membranes to promote the adhesion and differentiation of neuronal cells. We employed as model cell system the human neuroblastoma cell line SHSY5Y, which is a well-established system for studying neuronal differentiation. The investigation of viability and specific neuronal marker expression allowed assessment that the correct neuronal differentiation and the formation of neuronal network had taken place in vitro in the cells seeded on different biodegradable membranes. Overall, this study provides evidence that neural cell responses depend on the nature of the biodegradable polymer used to form the membranes, as well as on the dissolution, hydrophilic and, above all, mechanical membrane properties. PCL-PU membranes exhibit mechanical properties that improve neurite outgrowth and the expression of specific neuronal markers.

  11. How to include the variability of TMS responses in simulations: a speech mapping case study

    Science.gov (United States)

    De Geeter, N.; Lioumis, P.; Laakso, A.; Crevecoeur, G.; Dupré, L.

    2016-11-01

    When delivered over a specific cortical site, TMS can temporarily disrupt the ongoing process in that area. This allows mapping of speech-related areas for preoperative evaluation purposes. We numerically explore the observed variability of TMS responses during a speech mapping experiment performed with a neuronavigation system. We selected four cases with very small perturbations in coil position and orientation. In one case (E) a naming error occurred, while in the other cases (NEA, B, C) the subject appointed the images as smoothly as without TMS. A realistic anisotropic head model was constructed of the subject from T1-weighted and diffusion-weighted MRI. The induced electric field distributions were computed, associated to the coil parameters retrieved from the neuronavigation system. Finally, the membrane potentials along relevant white matter fibre tracts, extracted from DTI-based tractography, were computed using a compartmental cable equation. While only minor differences could be noticed between the induced electric field distributions of the four cases, computing the corresponding membrane potentials revealed different subsets of tracts were activated. A single tract was activated for all coil positions. Another tract was only triggered for case E. NEA induced action potentials in 13 tracts, while NEB stimulated 11 tracts and NEC one. The calculated results are certainly sensitive to the coil specifications, demonstrating the observed variability in this study. However, even though a tract connecting Broca’s with Wernicke’s area is only triggered for the error case, further research is needed on other study cases and on refining the neural model with synapses and network connections. Case- and subject-specific modelling that includes both electromagnetic fields and neuronal activity enables demonstration of the variability in TMS experiments and can capture the interaction with complex neural networks.

  12. Tree ring variability and climate response of Abies spectabilis along an elevation gradient in Mustang, Nepal

    DEFF Research Database (Denmark)

    Kharal, D.K.; Meilby, Henrik; Rayamajhi, S.

    2014-01-01

    In mountainous areas including the Himalayas, tree lines are expected to advance to higher altitudes due to global climate change affecting the distribution and growth of plant species. This study aimed at identifying the tree ring variability of Abies spectabilis (D. Don) and its response...... to the climate along an elevation gradient in the high Himalayas of central Nepal. Tree core samples were collected from four sites in Mustang district. All sites were located in the same valley and exposed to similar weather conditions. Out of 232 samples collected from the sites, Titi lower (2700 m), Titi...... upper (2900 m), Pangukhark (3100 m) and Lete upper (3300 m), 44, 40, 39 and 41 series were successfully cross-dated and ring width chronologies including 168, 79, 138 and 156 years previous to 2012 were developed, respectively. Statistically significant differences in average annual radial growth were...

  13. Trace metal pyritization variability in response to mangrove soil aerobic and anaerobic oxidation processes.

    Science.gov (United States)

    Machado, W; Borrelli, N L; Ferreira, T O; Marques, A G B; Osterrieth, M; Guizan, C

    2014-02-15

    The degree of iron pyritization (DOP) and degree of trace metal pyritization (DTMP) were evaluated in mangrove soil profiles from an estuarine area located in Rio de Janeiro (SE Brazil). The soil pH was negatively correlated with redox potential (Eh) and positively correlated with DOP and DTMP of some elements (Mn, Cu and Pb), suggesting that pyrite oxidation generated acidity and can affect the importance of pyrite as a trace metal-binding phase, mainly in response to spatial variability in tidal flooding. Besides these aerobic oxidation effects, results from a sequential extraction analyses of reactive phases evidenced that Mn oxidized phase consumption in reaction with pyrite can be also important to determine the pyritization of trace elements. Cumulative effects of these aerobic and anaerobic oxidation processes were evidenced as factors affecting the capacity of mangrove soils to act as a sink for trace metals through pyritization processes.

  14. Pastoral mobility as a response to climate variability in African drylands

    DEFF Research Database (Denmark)

    Adriansen, Hanne Kirstine

    1999-01-01

    The article outlines aspects of ‘the new paradigm’ for dryland ecosystems and pastoral production systems. Rationality of pastoralism was claimed by parts of the research community for decades, but especially among policy and development planners pastoralism was perceived as an irrational...... and destructive production system. With the new paradigm a coherent theory is provided linking the dynamics of drylands with pastoral strategies. Consequences of the new paradigm are analysed from a theoretical point of view, emphasis is on implications for pastoral mobility with a focus on pastoral systems...... in West Africa. In an example from Ferlo, Senegal, different types of pastoral mobility are discussed with special focus on the importance of scale. It is concluded that pastoral mobility is a rational response to climate variability and unpredictability in African drylands....

  15. Correlative changes in life-history variables in response to environmental change in a model organism.

    Science.gov (United States)

    Smallegange, Isabel M; Deere, Jacques A; Coulson, Tim

    2014-06-01

    Global change alters the environment, including increases in the frequency of (un)favorable events and shifts in environmental noise color. However, how these changes impact the dynamics of populations, and whether these can be predicted accurately has been largely unexamined. Here we combine recently developed population modeling approaches and theory in stochastic demography to explore how life history, morphology, and average fitness respond to changes in the frequency of favorable environmental conditions and in the color of environmental noise in a model organism (an acarid mite). We predict that different life-history variables respond correlatively to changes in the environment, and we identify different life-history variables, including lifetime reproductive success, as indicators of average fitness and life-history speed across stochastic environments. Depending on the shape of adult survival rate, generation time can be used as an indicator of the response of populations to stochastic change, as in the deterministic case. This work is a useful step toward understanding population dynamics in stochastic environments, including how stochastic change may shape the evolution of life histories.

  16. Dose-response modeling in mental health using stein-like estimators with instrumental variables.

    Science.gov (United States)

    Ginestet, Cedric E; Emsley, Richard; Landau, Sabine

    2017-02-21

    A mental health trial is analyzed using a dose-response model, in which the number of sessions attended by the patients is deemed indicative of the dose of psychotherapeutic treatment. Here, the parameter of interest is the difference in causal treatment effects between the subpopulations that take part in different numbers of therapy sessions. For this data set, interactions between random treatment allocation and prognostic baseline variables provide the requisite instrumental variables. While the corresponding two-stage least squares (TSLS) estimator tends to have smaller bias than the ordinary least squares (OLS) estimator; the TSLS suffers from larger variance. It is therefore appealing to combine the desirable properties of the OLS and TSLS estimators. Such a trade-off is achieved through an affine combination of these two estimators, using mean squared error as a criterion. This produces the semi-parametric Stein-like (SPSL) estimator as introduced by Judge and Mittelhammer (2004). The SPSL estimator is used in conjunction with multiple imputation with chained equations, to provide an estimator that can exploit all available information. Simulated data are also generated to illustrate the superiority of the SPSL estimator over its OLS and TSLS counterparts. A package entitled SteinIV implementing these methods has been made available through the R platform. © 2017 The Authors. Statistics in Medicine Published by John Wiley & Sons Ltd.

  17. Conserved and Variable Functions of the sigma(E Stress Response in Related Genomes.

    Directory of Open Access Journals (Sweden)

    2005-12-01

    Full Text Available Bacteria often cope with environmental stress by inducing alternative sigma (sigma factors, which direct RNA polymerase to specific promoters, thereby inducing a set of genes called a regulon to combat the stress. To understand the conserved and organism-specific functions of each sigma, it is necessary to be able to predict their promoters, so that their regulons can be followed across species. However, the variability of promoter sequences and motif spacing makes their prediction difficult. We developed and validated an accurate promoter prediction model for Escherichia coli sigma(E, which enabled us to predict a total of 89 unique sigma(E-controlled transcription units in E. coli K-12 and eight related genomes. sigma(E controls the envelope stress response in E. coli K-12. The portion of the regulon conserved across genomes is functionally coherent, ensuring the synthesis, assembly, and homeostasis of lipopolysaccharide and outer membrane porins, the key constituents of the outer membrane of Gram-negative bacteria. The larger variable portion is predicted to perform pathogenesis-associated functions, suggesting that sigma(E provides organism-specific functions necessary for optimal host interaction. The success of our promoter prediction model for sigma(E suggests that it will be applicable for the prediction of promoter elements for many alternative sigma factors.

  18. Urban heat island impacts on plant phenology: intra-urban variability and response to land cover

    Science.gov (United States)

    Zipper, Samuel C.; Schatz, Jason; Singh, Aditya; Kucharik, Christopher J.; Townsend, Philip A.; Loheide, Steven P., II

    2016-05-01

    Despite documented intra-urban heterogeneity in the urban heat island (UHI) effect, little is known about spatial or temporal variability in plant response to the UHI. Using an automated temperature sensor network in conjunction with Landsat-derived remotely sensed estimates of start/end of the growing season, we investigate the impacts of the UHI on plant phenology in the city of Madison WI (USA) for the 2012-2014 growing seasons. Median urban growing season length (GSL) estimated from temperature sensors is ˜5 d longer than surrounding rural areas, and UHI impacts on GSL are relatively consistent from year-to-year. Parks within urban areas experience a subdued expression of GSL lengthening resulting from interactions between the UHI and a park cool island effect. Across all growing seasons, impervious cover in the area surrounding each temperature sensor explains >50% of observed variability in phenology. Comparisons between long-term estimates of annual mean phenological timing, derived from remote sensing, and temperature-based estimates of individual growing seasons show no relationship at the individual sensor level. The magnitude of disagreement between temperature-based and remotely sensed phenology is a function of impervious and grass cover surrounding the sensor, suggesting that realized GSL is controlled by both local land cover and micrometeorological conditions.

  19. Androgen responsiveness to competition in humans: the role of cognitive variables

    Directory of Open Access Journals (Sweden)

    Oliveira GA

    2014-02-01

    Full Text Available Gonçalo A Oliveira,1 Rui F Oliveira1,2 1Unidade de Investigação em Eco-Etologia, ISPA – Instituto Universitário, Lisbon, Portugal; 2Champalimaud Neuroscience Program, Instituto Gulbenkian de Ciência, Oeiras, Portugal Abstract: Although androgens are commonly seen as male sex hormones, it has been established over the years that in both sexes, androgens also respond to social challenges. To explain the socially driven changes in androgens, two theoretical models have been proposed: the biosocial model and the challenge hypothesis. These models are typically seen as partly overlapping; however, they generate different predictions that are clarified here. In humans, sports competition and nonmetabolic competitive tasks have been used in the laboratory setting, as a proxy for agonistic interactions in animals. The results reviewed here show that the testosterone (T response to competition in humans is highly variable – the studies present postcompetition T levels and changes in T that depend on the contest outcome and that cannot be predicted by the current theoretical models. These conflicting results bring to the foreground the importance of considering cognitive factors that could moderate the androgen response to competition. Among these variables, we elect cognitive appraisal and its components as a key candidate modulating factor. It is known that T also modulates the cognitive processes that are relevant to performance in competition. In this article, we reviewed the evidence arising from studies investigating the effect of administering exogenous T and compare those results with the findings from studies that measured endogenous T levels. Finally, we summarized the importance of also considering the interaction between androgens and other hormones, such as cortisol, when investigating the social modulation of T, as proposed by the dual-hormone hypothesis. Keywords: testosterone, challenge hypothesis, biosocial model, cognitive

  20. Evaluation of simulated photolysis rates and their response to solar irradiance variability

    Science.gov (United States)

    Sukhodolov, Timofei; Rozanov, Eugene; Ball, William T.; Bais, Alkiviadis; Tourpali, Kleareti; Shapiro, Alexander I.; Telford, Paul; Smyshlyaev, Sergey; Fomin, Boris; Sander, Rolf; Bossay, Sébastien; Bekki, Slimane; Marchand, Marion; Chipperfield, Martyn P.; Dhomse, Sandip; Haigh, Joanna D.; Peter, Thomas; Schmutz, Werner

    2016-05-01

    The state of the stratospheric ozone layer and the temperature structure of the atmosphere are largely controlled by the solar spectral irradiance (SSI) through its influence on heating and photolysis rates. This study focuses on the uncertainties in the photolysis rate response to solar irradiance variability related to the choice of SSI data set and to the performance of the photolysis codes used in global chemistry-climate models. To estimate the impact of SSI uncertainties, we compared several photolysis rates calculated with the radiative transfer model libRadtran, using SSI calculated with two models and observed during the Solar Radiation and Climate Experiment (SORCE) satellite mission. The importance of the calculated differences in the photolysis rate response for ozone and temperature changes has been estimated using 1-D a radiative-convective-photochemical model. We demonstrate that the main photolysis reactions, responsible for the solar signal in the stratosphere, are highly sensitive to the spectral distribution of SSI variations. Accordingly, the ozone changes and related ozone-temperature feedback are shown to depend substantially on the SSI data set being used, which highlights the necessity of obtaining accurate SSI variations. To evaluate the performance of photolysis codes, we compared the results of eight, widely used, photolysis codes against two reference schemes. We show that, in most cases, absolute values of the photolysis rates and their response to applied SSI changes agree within 30%. However, larger errors may appear in specific atmospheric regions because of differences, for instance, in the treatment of Rayleigh scattering, quantum yields, or absorption cross sections.

  1. Evaluation of pleth variability index as a predictor of fluid responsiveness during orthotopic liver transplantation.

    Science.gov (United States)

    Konur, Huseyin; Erdogan Kayhan, Gulay; Toprak, Huseyin Ilksen; Bucak, Nizamettin; Aydogan, Mustafa Said; Yologlu, Saim; Durmus, Mahmut; Yılmaz, Sezai

    2016-07-01

    Fluid management is challenging and still remains controversial in orthotopic liver transplantation (OLT). The pleth variability index (PVI) has been shown to be a reliable predictor of fluid responsiveness of perioperative and critically ill patients; however, it has not been evaluated in OLT. This study was designed to examine whether the PVI can reliably predict fluid responsiveness in OLT and to compare PVI with other hemodynamic indexes that are measured using the PiCCO2 monitoring system. Twenty-five patients were enrolled in this study. Each patient was monitored using the noninvasive Masimo and PiCCO2 monitoring system. PVI was obtained with a Masimo pulse oximeter. Cardiac index was obtained using a transpulmonary thermodilution technique (CITPTD). Stroke volume variation (SVV), pulse pressure variation, and systemic vascular resistance index were measured using the PiCCO2 system. Fluid loading (10 mL/kg colloid) was performed at two different phases during the operation, and fluid responsiveness was defined as an increase in CITPTD ≥ 15%. During the dissection phase and the anhepatic phase, respectively, 14 patients (56%) and 18 patients (75%) were classified as responders. There were no differences between the baseline values of the PVI of responders and nonresponders. Area under the curve for PVI was 0.56 (sensitivity 35%, specificity 90%, p = 0.58) at dissection phase, and was 0.55 (sensitivity 55%, specificity 66%, p = 0.58) at anhepatic phase. Of the parameters, a higher area under the curve value was found for SVV. We conclude that PVI was unable to predict fluid responsiveness with sufficient accuracy in patients undergoing OLT, but the SVV parameter was reliable.

  2. On the watershed response to land use/cover change and climate variability in the Prairies

    Science.gov (United States)

    Ehsanzadeh, E.; van der Kamp, G.; Spence, C.

    2012-04-01

    Land use change for agriculture purposes or due to urbanization may change the movement patterns and also sources of water within a watershed boundary. It is of key interest to know how the integrated impact of these disturbances, along with a regime change due to natural climate variability or human induced climate change, affects runoff response behavior of a watershed. This study investigates changes in runoff production behavior of over 50 small to very large watersheds with drainage areas ranging from 35 to 160000 km2 in the North American Prairies. These depression-dominated watersheds which are characterized with strong memory properties have been subjected to diverse human disturbances. Our statistical analysis shows that there has been a range of diverse change in seasonal regimes of runoff as well as changes in snowfall versus rainfall patterns over the study area. This study shows that in watersheds with recorded history of disturbances the impact of human interference, along with modifications to climate inputs, on runoff response behavior is nonlinear, complex, and diverse. The results of this study suggest that different disturbances (i.e. removal of vegetation, changes in texture and structure of the soil through tilling or grading, ditching, construction of dams, etc.) may have varying or even opposite impacts on the residence time of water on the ground and in bodies of surface water such as streams or wetlands within the watershed boundaries. It seems that a change in watershed response behavior is a function of interaction among these diverse land use/cover changes as well as modifications to climate inputs. This complex response results in varying nonstationarity behaviors depending on the extent of each modification and also spatial scale of the watershed under study.

  3. Female anthropometric variability and their effects on predicted thermoregulatory responses to work in the heat

    Science.gov (United States)

    Yokota, Miyo; Berglund, Larry G.; Bathalon, Gaston P.

    2012-03-01

    The use of thermoregulatory models for assessing physiological responses of workers in thermally stressful situations has been increasing because of the risks and costs related to human studies. In a previous study (Yokota et al. Eur J Appl Physiol 104:297-302, 2008), the effects of anthropometric variability on predicted physiological responses to heat stress in U.S. Army male soldiers were evaluated. Five somatotypes were identified in U.S. Army male multivariate anthropometric distribution. The simulated heat responses, using a thermoregulatory model, were different between somatotypes. The present study further extends this line of research to female soldiers. Anthropometric somatotypes were identified using multivariate analysis [height, weight, percent body fat (%BF)] and the predicted physiological responses to simulated exercise and heat stress using a thermoregulatory model were evaluated. The simulated conditions included walking at ~3 mph (4.8 km/h) for 300 min and wearing battle dress uniform and body armor in a 30°C, 25% relative humidity (RH) environment without solar radiation. Five major somatotypes (tall-fat, tall-lean, average, short-lean, and short-fat), identified through multivariate analysis of anthropometric distributions, showed different tolerance levels to simulated heat stress: lean women were predicted to maintain their core temperatures (Tc) lower than short-fat or tall-fat women. The measured Tc of female subjects obtained from two heat studies (data1: 30°C, 32% RH, protective garments, ~225 w·m-2 walk for 90 min; data2: 32°C, 75% RH, hot weather battle dress uniform, ~378 ± 32 w·m-2 for 30 min walk/30 min rest cycles for 120 min) were utilized for validation. Validation results agreed with the findings in this study: fat subjects tended to have higher core temperatures than medium individuals (data2) and lean subjects maintained lower core temperatures than medium subjects (data1).

  4. Absorbable and biodegradable polymers

    CERN Document Server

    Shalaby, Shalaby W

    2003-01-01

    INTRODUCTION NOTES: Absorbable/Biodegradable Polymers: Technology Evolution. DEVELOPMENT AND APPLICATIONOF NEW SYSTEMS: Segmented Copolyesters with Prolonged Strength Retention Profiles. Polyaxial Crystalline Fiber-Forming Copolyester. Polyethylene Glycol-Based Copolyesters. Cyanoacrylate-Based Systems as Tissue Adhesives. Chitosan-Based Systems. Hyaluronic Acid-Based Systems. DEVELOPMENTS IN PREPARATIVE, PROCESSING, AND EVALUATION METHODS: New Approaches to the Synthesis of Crystalline. Fiber-Forming Aliphatic Copolyesters. Advances in Morphological Development to Tailor the Performance of Me

  5. Safe biodegradable fluorescent particles

    Science.gov (United States)

    Martin, Sue I.; Fergenson, David P.; Srivastava, Abneesh; Bogan, Michael J.; Riot, Vincent J.; Frank, Matthias

    2010-08-24

    A human-safe fluorescence particle that can be used for fluorescence detection instruments or act as a safe simulant for mimicking the fluorescence properties of microorganisms. The particle comprises a non-biological carrier and natural fluorophores encapsulated in the non-biological carrier. By doping biodegradable-polymer drug delivery microspheres with natural or synthetic fluorophores, the desired fluorescence can be attained or biological organisms can be simulated without the associated risks and logistical difficulties of live microorganisms.

  6. Biodegradation of Silk Biomaterials

    OpenAIRE

    Bochu Wang; Yang Cao

    2009-01-01

    Silk fibroin from the silkworm, Bombyx mori, has excellent properties such as biocompatibility, biodegradation, non-toxicity, adsorption properties, etc. As a kind of ideal biomaterial, silk fibroin has been widely used since it was first utilized for sutures a long time ago. The degradation behavior of silk biomaterials is obviously important for medical applications. This article will focus on silk-based biomaterials and review the degradation behaviors of silk materials.

  7. Governmental responses and smallholders' adaptations to climatic variability in southeastern Mexico

    Science.gov (United States)

    Mardero Jimenez, Silvia Sofia; Schmook, Birgit; Christman, Zachary; Radel, Claudia

    2016-04-01

    Maize agriculture comprises a third of the area under cultivation in Mexico (75 million hectares), with only a quarter of this crop irrigated artificially. With the great dependence of the country's dominant crop on natural rainfall, there is potential for major losses in maize production due to climatic events, such as irregular rainfalls, droughts, and hurricanes. In 2012, droughts alone caused losses of 16 billion Mexican pesos nationwide in the agricultural sector. Over the last decades, political and economic pressures in the agrarian sector have further stressed Mexican smallholder farmers, as they have to respond to a combination of economic and climatic factors. This interdisciplinary study first documents local climate changes and then explores smallholder farmers' adaptations and governmental policy responses to the variable and changing precipitation and temperature patterns across southeastern Mexico. To assess local climate changes, we analyzed precipitation and temperature data from the land-based weather station network of CONAGUA for the 1973-2012 period. Precipitation anomalies were estimated to evaluate the annual and seasonal stability, deficit, or surplus; and linear regressions used to evaluate precipitation and temperature trends. Climatic analysis demonstrated, 1) a considerable increase in temperature across the study area; 2) a decline in precipitation across a sub-section; 3) increased drought frequency; and 4) an increase in negative anomalies in recent years. We then combine findings from our previous research (Mardero et al. 2014 and Mardero et al. 2015), based on interviews with 150 swidden maize smallholders in 10 communities, to new data from in-depth interviews with managers of local and regional agricultural associations and with members of governmental institutions in charge of climate policy implementation (n=19). The new data allow us to explore governmental responses to climatic variability in the agricultural sector in direct

  8. Environmental variability study on the measured responses of Runyang Cablestayed Bridge using wavelet packet analysis

    Institute of Scientific and Technical Information of China (English)

    DING YouLiang; LI AiQun; LIU Tao

    2008-01-01

    The structural damage alarming method based on wavelet packet energy spectrum (WPES) for long-span cable-stayed bridges is presented through combination of ambient vibration test and wavelet packet analysis.The environmental variability in the measured WPES and damage alarming indices ERVD of the Runyang Ca-ble-stayed Bridge are discussed in detail using the wavelet packet analysis of the measured acceleration responses of the bridge under daily environmental condi-tions.The analysis results reveal that the actual environmental conditions includ-ing traffic Ioadings,environmental temperature and typhoon Ioadings have re-markable correlations with the measured WPES.The changes of environmental temperature have a long-term trend influence on the WPES,while the influences of traffic and typhoon Ioadings on the measured WPES of the bridge present instan-taneous changes because of the nonstationary properties of the Ioadings.The analysis results of the measured responses further reveal that the damage alarm-ing indices ERVD can sensitively reflect the influences of environmental tempera-ture and typhoon Ioadings on the dynamic properties of Runyang Cable-stayed Bridge.Therefore,the proposed structural damage alarming indices ERVD under ambient vibrations are suitable for real-time damage alarming for long-span ca-ble-stayed bridges.

  9. Environmental variability study on the measured responses of Runyang Cablestayed Bridge using wavelet packet analysis

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The structural damage alarming method based on wavelet packet energy spectrum (WPES) for long-span cable-stayed bridges is presented through combination of ambient vibration test and wavelet packet analysis. The environmental variability in the measured WPES and damage alarming indices ERVD of the Runyang Cable-stayed Bridge are discussed in detail using the wavelet packet analysis of the measured acceleration responses of the bridge under daily environmental conditions. The analysis results reveal that the actual environmental conditions including traffic loadings, environmental temperature and typhoon loadings have remarkable correlations with the measured WPES. The changes of environmental temperature have a long-term trend influence on the WPES, while the influences of traffic and typhoon loadings on the measured WPES of the bridge present instantaneous changes because of the nonstationary properties of the loadings. The analysis results of the measured responses further reveal that the damage alarming indices ERVD can sensitively reflect the influences of environmental temperature and typhoon loadings on the dynamic properties of Runyang Cable-stayed Bridge. Therefore, the proposed structural damage alarming indices ERVD under ambient vibrations are suitable for real-time damage alarming for long-span cable-stayed bridges.

  10. Dendrogeomorphically derived slope response to decadal and centennial scale climate variability: Black Mesa, Arizona, USA

    Directory of Open Access Journals (Sweden)

    L. A. Scuderi

    2008-08-01

    Full Text Available A major impediment to an understanding of the links between climate and landscape change, has been the relatively coarse resolution of landscape response measures (rates of weathering, sediment production, erosion and transport relative to the higher resolution of the climatic signal (precipitation and temperature on hourly to annual time scales. A combination of high temporal and spatial resolution dendroclimatic and dendrogeomorphic approaches were used to study relationships between climatic variability and hillslope and valley floor dynamics in a small drainage basin in the Colorado Plateau of northeastern Arizona, USA Dendrogeomorphic and vegetation evidence from slopes and valley bottoms, including root exposure, bending of trunks, change in plant cover and burial and exhumation of valley bottom trees and shrubs, suggest that the currently observed process of root colonization and rapid breakdown of the weakly cemented bedrock by subaerial weathering, related to periodic dry/wet cycle induced changes in vegetation cover, has lead to a discontinuous, climate-controlled production of sediment from these slopes. High-amplitude precipitation shifts over the last 2000-years may exert the largest control on landscape processes and may be as, or more, important than other hypothesized causal mechanisms (e.g. ENSO frequency and intensity, flood frequency in eroding slopes and producing sediments that ultimately impact higher order drainages in the region. Current vegetation response to a prolonged drought over the past decade suggests that another major transition, incorporating vegetation change, slope erosion, sediment production and subsequent valley floor deposition, may be in its initial phase.

  11. Topographic position modulates the mycorrhizal response of oak trees to interannual rainfall variability.

    Science.gov (United States)

    Querejeta, José I; Egerton-Warburton, Louise M; Allen, Michael F

    2009-03-01

    California coast live oak (Quercus agrifolia) forms tripartite symbiotic associations with arbuscular (AMF) and ectomycorrhizal (EMF) fungi. We selected oak individuals differing in topographic position and depth to groundwater (mesic valley vs. xeric hill sites) to investigate changes of tree mycorrhizal status in response to interannual rainfall variability. EMF root colonization, as well as hyphal abundance and viability in upper rhizosphere soil (0-30 cm), were negatively affected by severe multi-year drought, although not to the same extent in each topographic location. Oak trees growing in hill sites showed EMF colonization levels drought. By contrast, oaks in valley sites maintained much higher EMF colonization (>19%) in upper roots during drought. EMF root colonization increased sharply at both topographic positions during the ensuing wet year (78% in valley, 49% in hill), which indicates that the mycorrhizal status of roots in upper rhizosphere soil is highly responsive to interannual rainfall variability. Across sites and years, percentage EMF colonization and soil hyphal density and viability were strongly positively correlated with soil moisture potential, but percentage AMF root colonization was not. Interestingly, changes in percentage EMF root colonization and density of viable hyphae between a wet and a dry year were proportionally much greater in xeric hill sites than in mesic valley sites. The mycorrhizal status of oak trees was particularly responsive to changes in soil moisture at the hill sites, where roots in upper rhizosphere soil shifted from almost exclusively AMF during severe drought to predominantly EMF during the ensuing wet year. By contrast, the mycorrhizal status of oaks in the valley sites was less strongly coupled to current meteorological conditions, as roots in upper soil layers remained predominantly EMF during both a dry and a wet year. Canopy shading and hydraulic lift by oaks in valley sites likely contributed to maintain the

  12. Himalayan River Terraces as A Landscape Response to Quaternary Summer Monsoon Variability

    Science.gov (United States)

    Jonell, T. N.; Clift, P. D.

    2013-12-01

    In order to interpret marine sedimentary archives as records of the erosional response to Asian monsoon variability, we must first recognize how transport processes affect the storage and release of sediment to the ocean. River terraces, such as found in the Greater Himalaya, provide a pivotal role in the source-to-sink story, because this is where sediment storage occurs and is likely modulated. We investigate the role that climate plays in controlling erosion and sediment flux to the Indus delta and fan by looking at the Indus River system, which is dominated by the strong forcing of the Asian monsoon, as well as winter Westerly winds. Paleoceanographic, speleothem, and lacustrine records indicate that summer monsoon intensity was strong from 29 to 37 ka, decreased after that time until ~16 ka, reached maximum intensity from 8 to 10 ka, and then weakened until ~3 ka. Some lacustrine records, however, indicate a more complex pattern of monsoon variability in the Greater Himalaya, which contrasts with monsoonal forcing in central India. This disagreement suggests that floodplains of major river systems may not experience the same climatic conditions as their mountain sources, resulting in contrasting landscape responses to climate change. High altitude river valleys, at least north ofthe Greater Himalaya, appear to be sensitive to monsoon strength because they lie on the periphery of the present rainfall maximum, in the Himalayan rain shadow. These steep river valleys may be affected by landslide damming during periods of increase moisture transport and strong monsoonal precipitation, where damming provides sediment storage through valley-filling and later sediment release through gradual incision or dam-bursting. The Zanskar River, a major tributary to the upper Indus River, provides a record of the erosional response of mountain river valleys to these extreme phases through river terracing. New OSL ages from alluvial terraces indicate reworking of sediment and

  13. BDNF variability in opioid addicts and response to methadone treatment: preliminary findings.

    Science.gov (United States)

    de Cid, R; Fonseca, F; Gratacòs, M; Gutierrez, F; Martín-Santos, R; Estivill, X; Torrens, M

    2008-07-01

    Brain-derived neurotrophic factor (BDNF) signaling pathways have been shown to be essential for opioid-induced plasticity. We conducted an exploratory study to evaluate BDNF variability in opioid addict responders and nonresponders to methadone maintenance treatment (MMT). We analyzed 21 single nucleotide polymorphisms (SNPs) across the BDNF genomic region. Responders and nonresponders were classified by means of illicit opioid consumption detected in random urinalysis. Patients were assessed by a structured interview (Psychiatric Research Interview for Substance and Mental Disorders (PRISM)-DSM-IV) and personality was evaluated by the Cloninger's Temperament and Character Inventory. No clinical, environmental and treatment characteristics were different between the groups, except for the Cooperativeness dimension (P < 0.001). Haplotype block analysis showed a low-frequency (2.7%) haplotype (13 SNPs) in block 1, which was more frequent in the nonresponder group than in the responder group (4/42 vs. 1/135; P(corrected) = 0.023). Fine mapping in block 1 allows us to identify a haplotype subset formed by only six SNPs (rs7127507, rs1967554, rs11030118, rs988748, rs2030324 and rs11030119) associated with differential response to MMT (global P sim = 0.011). Carriers of the CCGCCG haplotype had an increased risk of poorer response, even after adjusting for Cooperativeness score (OR = 20.25 95% CI 1.46-280.50, P = 0.025). These preliminary results might suggest the involvement of BDNF as a factor to be taken into account in the response to MMT independently of personality traits, environmental cues, methadone dosage and psychiatric comorbidity.

  14. Anaerobic Biodegradation of Detergent Surfactants

    Directory of Open Access Journals (Sweden)

    Erich Jelen

    2009-03-01

    Full Text Available Detergent surfactantscan be found in wastewater in relevant concentrations. Most of them are known as ready degradable under aerobic conditions, as required by European legislation. Far fewer surfactants have been tested so far for biodegradability under anaerobic conditions. The natural environment is predominantly aerobic, but there are some environmental compartments such as river sediments, sub-surface soil layer and anaerobic sludge digesters of wastewater treatment plants which have strictly anaerobic conditions. This review gives an overview on anaerobic biodegradation processes, the methods for testing anaerobic biodegradability, and the anaerobic biodegradability of different detergent surfactant types (anionic, nonionic, cationic, amphoteric surfactants.

  15. A simple model for the spatially-variable coastal response to hurricanes

    Science.gov (United States)

    Stockdon, H.F.; Sallenger, A.H.; Holman, R.A.; Howd, P.A.

    2007-01-01

    The vulnerability of a beach to extreme coastal change during a hurricane can be estimated by comparing the relative elevations of storm-induced water levels to those of the dune or berm. A simple model that defines the coastal response based on these elevations was used to hindcast the potential impact regime along a 50-km stretch of the North Carolina coast to the landfalls of Hurricane Bonnie on August 27, 1998, and Hurricane Floyd on September 16, 1999. Maximum total water levels at the shoreline were calculated as the sum of modeled storm surge, astronomical tide, and wave runup, estimated from offshore wave conditions and the local beach slope using an empirical parameterization. Storm surge and wave runup each accounted for ∼ 48% of the signal (the remaining 4% is attributed to astronomical tides), indicating that wave-driven process are a significant contributor to hurricane-induced water levels. Expected water levels and lidar-derived measures of pre-storm dune and berm elevation were used to predict the spatially-varying storm-impact regime: swash, collision, or overwash. Predictions were compared to the observed response quantified using a lidar topography survey collected following hurricane landfall. The storm-averaged mean accuracy of the model in predicting the observed impact regime was 55.4%, a significant improvement over the 33.3% accuracy associated with random chance. Model sensitivity varied between regimes and was highest within the overwash regime where the accuracies were 84.2% and 89.7% for Hurricanes Bonnie and Floyd, respectively. The model not only allows for prediction of the general coastal response to storms, but also provides a framework for examining the longshore-variable magnitudes of observed coastal change. For Hurricane Bonnie, shoreline and beach volume changes within locations that experienced overwash or dune erosion were two times greater than locations where wave runup was confined to the foreshore (swash regime

  16. Study of process variables in industrial acetic fermentation by a continuous pilot fermentor and response surfaces.

    Science.gov (United States)

    Garrido-Vidal, Diego; Pizarro, Consuelo; González-Sáiz, José M

    2003-01-01

    The modeling and optimization of industrial processes requires an intensive study of the factors involved. In this work, a continuous pilot system for studying the industrial process of acetic fermentation is developed. A Doehlert design is applied to the five variables involved in the pilot process. This experimental design allows reduction of the experimental burden and the maximum amount of information to be obtained, studying the factors at different levels depending on their significance. The experimental system provides a robust measure of the specific growth rate and the rates of substrates consumption and acetic acid production, related to the flow of effluent stream evaluated in the steady state. The results demonstrate the growth-associated kinetics of substrates and product, and the yield factors are calculated with low values of variances for the coefficients, i.e., within the range 1-11%. The specific growth rate suits the quadratic model proposed. The response surfaces generated by the model are applied to explain the behavior of the bacterial growth and, therefore, the effects of the process variables studied over the acetic acid production. Very low levels of ethanol or oxygen make the acetification rate decrease, and a saturation effect with high levels of ethanol or oxygen is also deduced. The effects of the aeration rate, agitation, and overpressure suggest a kind of inhibition of the acetic acid production caused by the oxygen that has not been practically studied before. The temperature strengthens the inhibitory effect of the ethanol and the oxygen. The conclusions of this work consolidate the structure of a hybrid model for the acetic fermentation.

  17. Response of durum wheat to water variability under climate change scenarios in southern Sardinia

    Science.gov (United States)

    Soddu, Antonino; Deidda, Roberto; Marrocu, Marino; Meloni, Roberto; Paniconi, Claudio; Ludwig, Ralf; Sodde, Marcella; Mascaro, Giuseppe; Perra, Enrica

    2013-04-01

    Durum wheat is the most important C3 rainfed crop in southern Sardinia, Italy and is highly vulnerable to climate variability. This region has experienced severe drought conditions and problems of competing water demands during the last decades. Within the framework of European (1) and Regional (2) research projects, a study was conducted to evaluate the effects of increased maximum temperature and high rainfall variability on durum wheat yield, as part of an effort to devise strategies for water management and adaptation at the field and catchment scales in southern Sardinia. Towards this goal, the AquaCrop model was calibrated and its predictive performance was tested in the period from 1995 to 2012 using daily meteorological data and durum wheat (CV Creso) yield measurements from the experimental fields of the Agris Research Agency in Ussana (Sardinia, Italy). During the verification period, the model showed a good performance with a significant correlation between observed and simulated yield for durum wheat and a very good estimation of the water stress conditions during the drought period in 1995. Next, four future scenarios of climate change were simulated with AquaCrop to predict wheat yield responses and to investigate water availability for rainfed and irrigated crops for the 30-year periods 2011-2040, 2041-2070, and 2071-2100. The simulated future scenarios show potential improved productivity arising from the increased CO2 concentration. This positive outlook is however tempered by increased uncertainty and fluctuations in rainfall during the fall and early winter periods (September-December). The possible tradeoffs between these factors, as well as the expected negative effects of increased maximum temperatures, are being further examined. (1) Climate Induced Changes in the Mediterranean Region (CLIMB), funded by the European Commission 7th Framework Program. (2) Valutazione degli impatti sul comportamento idrologico dei bacini idrografici e sulle

  18. Effects of Oxygen on Biodegradation of Fuels in a Corroding Environment

    Science.gov (United States)

    2013-06-12

    known to be more labile than hydrocarbons to anaerobic biodegradation (Aktas, et al, 2010), so the preferential loss of these peaks from the...the contention that hydrocarbon removal was due at least in part to biodegradation by seawater microorganisms. Benzoate, cresols and alkanoic acids...RESPONSIBLE PERSON 19b. TELEPHONE NUMBER (Include area code) · Oxygen Effects on Biodegradation of Fuels in a Corroding Environment Deniz F. Aktas

  19. Biodegradable and edible gelatine actuators for use as artificial muscles

    Science.gov (United States)

    Chambers, L. D.; Winfield, J.; Ieropoulos, I.; Rossiter, J.

    2014-03-01

    The expense and use of non-recyclable materials often requires the retrieval and recovery of exploratory robots. Therefore, conventional materials such as plastics and metals in robotics can be limiting. For applications such as environmental monitoring, a fully biodegradable or edible robot may provide the optimum solution. Materials that provide power and actuation as well as biodegradability provide a compelling dimension to future robotic systems. To highlight the potential of novel biodegradable and edible materials as artificial muscles, the actuation of a biodegradable hydrogel was investigated. The fabricated gelatine based polymer gel was inexpensive, easy to handle, biodegradable and edible. The electro-mechanical performance was assessed using two contactless, parallel stainless steel electrodes immersed in 0.1M NaOH solution and fixed 40 mm apart with the strip actuator pinned directly between the electrodes. The actuation displacement in response to a bias voltage was measured over hydration/de-hydration cycles. Long term (11 days) and short term (1 hour) investigations demonstrated the bending behaviour of the swollen material in response to an electric field. Actuation voltage was low (biodegradable and edible artificial muscles could help to drive the development of environmentally friendly robotics.

  20. Ecohydrological responses of dense canopies to environmental variability: 1. Interplay between vertical structure and photosynthetic pathway

    Science.gov (United States)

    Drewry, D. T.; Kumar, P.; Long, S.; Bernacchi, C.; Liang, X.-Z.; Sivapalan, M.

    2010-12-01

    Vegetation acclimation to changing climate, in particular elevated atmospheric concentrations of carbon dioxide (CO2), has been observed to include modifications to the biochemical and ecophysiological functioning of leaves and the structural components of the canopy. These responses have the potential to significantly modify plant carbon uptake and surface energy partitioning, and have been attributed with large-scale changes in surface hydrology over recent decades. While the aggregated effects of vegetation acclimation can be pronounced, they often result from subtle changes in canopy properties that require the resolution of physical, biochemical and ecophysiological processes through the canopy for accurate estimation. In this paper, the first of two, a multilayer canopy-soil-root system model developed to capture the emergent vegetation responses to environmental change is presented. The model incorporates both C3 and C4 photosynthetic pathways, and resolves the vertical radiation, thermal, and environmental regimes within the canopy. The tight coupling between leaf ecophysiological functioning and energy balance determines vegetation responses to climate states and perturbations, which are modulated by soil moisture states through the depth of the root system. The model is validated for three growing seasons each for soybean (C3) and maize (C4) using eddy-covariance fluxes of CO2, latent, and sensible heat collected at the Bondville (Illinois) Ameriflux tower site. The data set provides an opportunity to examine the role of important environmental drivers and model skill in capturing variability in canopy-atmosphere exchange. Vertical variation in radiative states and scalar fluxes over a mean diurnal cycle are examined to understand the role of canopy structure on the patterns of absorbed radiation and scalar flux magnitudes and the consequent differences in sunlit and shaded source/sink locations through the canopies. An analysis is made of the impact of

  1. Dissociation in Response to Methylphenidate on Response Variability in a Group of Medication Naive Children with ADHD

    Science.gov (United States)

    Johnson, Katherine A.; Barry, Edwina; Bellgrove, Mark A.; Cox, Marie; Kelly, Simon P.; Daibhis, Aoife; Daly, Michael; Keavey, Michelle; Watchorn, Amy; Fitzgerald, Michael; McNicholas, Fiona; Kirley, Aiveen; Robertson, Ian H.; Gill, Michael

    2008-01-01

    Increased variability in reaction time (RT) has been proposed as a cardinal feature of attention deficit hyperactivity disorder (ADHD). Increased variability during sustained attention tasks may reflect inefficient fronto-striatal and fronto-parietal circuitry; activity within these circuits is modulated by the catecholamines. A disruption to…

  2. Responses of carbon isotope discrimination in C4 plant to variable N and water supply

    Science.gov (United States)

    Yang, Hao; Li, Shenggong

    2016-04-01

    Understanding variations and underlying mechanisms of carbon isotope discrimination (Δ) in C4 species is critical for predicting the effects of change in C3/C4 ratio of plant community on ecosystem processes and functionning. However, little is known about the effects of soil resource gradients on Δ of C4 plants. To address Δ responses to drought and nitrogen supply, the leaf carbon isotope composition, bundle sheath leakiness (BLS), and leaf gas exchange (A, gs, Ci/Ca) were measured on Cleistogenes squarrosa, a dominant C4 species in the Inner Mongolia grassland. C. squarrosa were grown in controlled-environment pots from seed under a combination of water and N supply. High N availability and drought stimulated photosynthetic rate (A) and further decreased the ratio of internal and ambient CO2 concentrations (Ci/Ca) through increasing leaf N content. BLS was higher under high N supply and was unchanged by drought. There was significant interaction between N and water supply to affect BLS and Ci/Ca. Δ was negatively related to Ci/Ca and was positively related to BLS. Tradeoff between the responses of BLS and Ci/Ca to changing environmental conditions kept leaf Δ relatively stable, which was also supported by a field N addition experiment. Our results suggested leaf Δ of C4 plant was unchanged under variable water and N environment conditions although the operating efficiency of C4 pathway and CO2 concentration in photosynthesis were changed. Our findings have implications for predicting the change of C3/C4 ratio of plant community and understanding ecosystem processes and functionning.

  3. Global change ecotoxicology: Identification of early life history bottlenecks in marine invertebrates, variable species responses and variable experimental approaches.

    Science.gov (United States)

    Byrne, M

    2012-05-01

    Climate change is a threat to marine biota because increased atmospheric CO₂ is causing ocean warming, acidification, hypercapnia and decreased carbonate saturation. These stressors have toxic effects on invertebrate development. The persistence and success of populations requires all ontogenetic stages be completed successfully and, due to their sensitivity to environmental stressors, developmental stages may be a population bottleneck in a changing ocean. Global change ecotoxicology is being used to identify the marine invertebrate developmental stages vulnerable to climate change. This overview of research, and the methodologies used, shows that most studies focus on acidification, with few studies on ocean warming, despite a long history of research on developmental thermotolerance. The interactive effects of stressors are poorly studied. Experimental approaches differ among studies. Fertilization in many species exhibits a broad tolerance to warming and/or acidification, although different methodologies confound inter-study comparisons. Early development is susceptible to warming and most calcifying larvae are sensitive to acidification/increased pCO₂. In multistressor studies moderate warming diminishes the negative impact of acidification on calcification in some species. Development of non-calcifying larvae appears resilient to near-future ocean change. Although differences in species sensitivities to ocean change stressors undoubtedly reflect different tolerance levels, inconsistent handling of gametes, embryos and larvae probably influences different research outcomes. Due to the integrative 'developmental domino effect', life history responses will be influenced by the ontogenetic stage at which experimental incubations are initiated. Exposure to climate change stressors from early development (fertilization where possible) in multistressor experiments is needed to identify ontogenetic sensitivities and this will be facilitated by more consistent

  4. Parametric study of influence of stiffener variables on postbuckling response of frame-stiffened composite panels

    Science.gov (United States)

    Sanz-Douglass, Gabriela J.

    Traditional aircraft composite stiffened panels are designed to avoid buckling of the skin at service loads, to prevent initiation and growth of delamination damages. In stitched composites, the stitching provides reinforcement against delamination; therefore, the structure can be designed for operation in a post buckled state with local skin buckling. The novel stitched stiffened composite panel concept titled Pultruded-Rod Stiffened Efficient Unitized Structure, PRSEUS, was designed specifically for operating in the postbuckling regime, yet the nonlinear postbuckling behavior of PRSEUS has not been explored fully. This thesis presents a finite element analysis based trade study to understand influence of frame stiffener design variables on the nonlinear postbuckling response of the PRSEUS panel concept. The trade study allowed exploration of the design space as a first step towards design optimization. It also allowed discovery of some of the challenges of post processing that must be addressed to enable an automated surrogate based design optimization of the PRESUS stiffened panel concept for operation in postbuckling regimes.

  5. Responsiveness of Food Security Reporting to Environmental Variability and Agricultural Production Deficits

    Science.gov (United States)

    Brickley, E. B.; Brown, M. E.

    2010-12-01

    This paper uses 1342 food security update reports from the US Agency for International Development (USAID)’s Famine Early Warning System Network (FEWS NET) in an analysis that focuses on the environmental, market, and livelihood influences on the food security in 17 countries in Africa from 2000-2009. A textual analysis was conducted using the reports as a primary data source to evaluate the responsiveness of food security analysis to environmental variability and food production deficits. The research shows that FEWS NET analysts demonstrate a consistent approach across all 17 countries as to the discussion and use of rainfall information, agricultural production, food prices and food access parameters. There are significant differences in the use of remote sensing and other technical information between East, West and Southern African country analysts, with satellite remote sensing of vegetation being used 28% of the time, rainfall imagery 84% and gridded crop models only 10% of the time. Significantly more discussion of biophysical information was seen during the rainy season than during the dry season, and different satellite products were used during periods of drought than periods of adequate moisture. As the demand for early warning information grows to more countries in different ecosystems, there is likely to be an increased need for the effective utilization of remote sensing, market, and livelihood data, and it is also probable that this information will be critical for improved policy-making regarding climate extremes in the future.

  6. Aquifer response to regional climate variability in a part of Kashmir Himalaya in India

    Science.gov (United States)

    Jeelani, Gh

    2008-12-01

    Forty major perennial springs, under different lithological controls, in a part of Kashmir Himalaya in India were studied to understand the response of spring discharges to regional climate variability. The average monthly spring discharge is high in Triassic Limestone-controlled springs (karst springs) and low in alluvium- and Karewa-controlled springs. In general, the measured monthly spring discharges show an inverse relation with the monthly precipitation data. However, a direct correlation exists between the spring discharges and the degree of snow/ice melt. The results suggest that the creation of a low and continuous (but stable) recharge from the Triassic Limestone and Panjal Trap aquifers, due to blockage of groundwater flow between strata with contrasting hydraulic conductivity, attenuates the discharge and gives rise to small fluctuations in the alluvium- and Karewa-controlled springs. The average monthly discharge of the karst and alluvial springs showed an overall decreasing trend for two and a half decades, with the lowest discharge recorded in 2001. The study revealed that the regional/global warming and below-normal precipitation in the period of snow accumulation (PSA) has triggered the receding of glaciers and attenuation of spring discharges.

  7. The Impact of Sources of Variability on Parametric Response Mapping of Lung CT Scans.

    Science.gov (United States)

    Boes, Jennifer L; Bule, Maria; Hoff, Benjamin A; Chamberlain, Ryan; Lynch, David A; Stojanovska, Jadranka; Martinez, Fernando J; Han, Meilan K; Kazerooni, Ella A; Ross, Brian D; Galbán, Craig J

    2015-09-01

    Parametric response mapping (PRM) of inspiration and expiration computed tomography (CT) images improves the radiological phenotyping of chronic obstructive pulmonary disease (COPD). PRM classifies individual voxels of lung parenchyma as normal, emphysematous, or nonemphysematous air trapping. In this study, bias and noise characteristics of the PRM methodology to CT and clinical procedures were evaluated to determine best practices for this quantitative technique. Twenty patients of varying COPD status with paired volumetric inspiration and expiration CT scans of the lungs were identified from the baseline COPD-Gene cohort. The impact of CT scanner manufacturer and reconstruction kernels were evaluated as potential sources of variability in PRM measurements along with simulations to quantify the impact of inspiration/expiration lung volume levels, misregistration, and image spacing on PRM measurements. Negligible variation in PRM metrics was observed when CT scanner type and reconstruction were consistent and inspiration/expiration lung volume levels were near target volumes. CT scanner Hounsfield unit drift occurred but remained difficult to ameliorate. Increasing levels of image misregistration and CT slice spacing were found to have a minor effect on PRM measurements. PRM-derived values were found to be most sensitive to lung volume levels and mismatched reconstruction kernels. As with other quantitative imaging techniques, reliable PRM measurements are attainable when consistent clinical and CT protocols are implemented.

  8. Response of female beetles to LIDAR derived topographic variables in Eastern boreal mixedwood forests (Coleoptera, Carabidae).

    Science.gov (United States)

    Work, Timothy T; Onge, Benoit St; Jacobs, J M

    2011-01-01

    Biodiversity monitoring is increasingly being bolstered with high resolution data derived from remote sensing such as LIDAR (Light Detection and Ranging). We derived a series of topographical variables, including slope, azimuth, ground curvature and flow accumulation from LIDAR images and compared these to captures of female carabids in pitfall traps in Eastern boreal mixedwood forests. We developed a series of species-specific logistic models predicting the proportion of females for eight dominant species, including Agonum retractum, Calathus ingratus, Platynus decentis, Pterostichus adstrictus, Pterostichus coracinus, Pterostichus pensylvanicus, Sphaeroderus nitidicollis and Synuchus impunctatus. We used these models to test three hypotheses related to how the modest topography in boreal forests could influence the availability of microhabitats and possibly potential sites for oviposition and larval development. In general, topographic features such as north facing slopes and high flow accumulation were important predictors of the proportion of females. Models derived from larger scale topography, such as hillsides or small watersheds on the order of ¼-1 ha were better predictors of the proportion of females than were models derived from finer scale topography such as hummocks and small depressions. We conclude that topography likely influences the distribution of carabids based on hydrological mechanisms rather than factors related to temperature. We further suggest based on the scale of responses that these hydrological mechanisms may be linked to the attenuation of past disturbances by wildfire and the propensity of unburned forest patches and fire skips.

  9. Origins of Total-Dose Response Variability in Linear Bipolar Microcircuits

    Energy Technology Data Exchange (ETDEWEB)

    BARNABY,H.J.; CIRBA,C.R.; SCHRIMPF,R.D.; FLEETWOOD,D.M.; PEASE,R.L.; SHANEYFELT,MARTY R.; TURFLINGER,T.; KRIEG,J.F.; MAHER,M.C.

    2000-11-15

    LM1ll voltage comparators exhibit a wide range of total-dose-induced degradation. Simulations show this variability may be a natural consequence of the low base doping of the substrate PNP (SPNP) input transistors. Low base doping increases the SPNP's collector to base breakdown voltage, current gain, and sensitivity to small fluctuations in the radiation-induced oxide defect densities. The build-up of oxide trapped charge (N{sub ot}) and interface traps (N{sub it}) is shown to be a function of pre-irradiation bakes. Experimental data indicate that, despite its structural similarities to the LM111, irradiated input transistors of the LM124 operational amplifier do not exhibit the same sensitivity to variations in pre-irradiation thermal cycles. Further disparities in LM111 and LM124 responses may result from a difference in the oxide defect build-up in the two part types. Variations in processing, packaging, and circuit effects are suggested as potential explanations.

  10. Hydrocarbon biodegradation in intertidal wetland sediments.

    Science.gov (United States)

    McGenity, Terry J

    2014-06-01

    Intertidal wetlands, primarily salt marsh, mangrove and mudflats, which provide many essential ecosystem services, are under threat on numerous fronts; a situation that is made worse by crude-oil pollution. Microbes are the main vehicle for remediation of such sediments, and new discoveries, such as novel biodegradation pathways, means of accessing oil, multi-species interactions, and community-level responses to oil addition, are helping us to understand, predict and monitor the fate of oil. Despite this, there are many challenges, not least because of the heterogeneity of these ecosystems and the complexity of crude oil. For example, there is growing awareness about the toxicity of the oxygenated products that result from crude-oil weathering, which are difficult to degrade. This review highlights how developments in areas as diverse as systems biology, microbiology, ecology, biogeochemistry and analytical chemistry are enhancing our understanding of hydrocarbon biodegradation and thus bioremediation of oil-polluted intertidal wetlands.

  11. Response variability in Attention-Deficit/Hyperactivity Disorder: a neuronal and glial energetics hypothesis

    Directory of Open Access Journals (Sweden)

    Auerbach Judith G

    2006-08-01

    Full Text Available 1. Abstract Background Current concepts of Attention-Deficit/Hyperactivity Disorder (ADHD emphasize the role of higher-order cognitive functions and reinforcement processes attributed to structural and biochemical anomalies in cortical and limbic neural networks innervated by the monoamines, dopamine, noradrenaline and serotonin. However, these explanations do not account for the ubiquitous findings in ADHD of intra-individual performance variability, particularly on tasks that require continual responses to rapid, externally-paced stimuli. Nor do they consider attention as a temporal process dependent upon a continuous energy supply for efficient and consistent function. A consideration of this feature of intra-individual response variability, which is not unique to ADHD but is also found in other disorders, leads to a new perspective on the causes and potential remedies of specific aspects of ADHD. The hypothesis We propose that in ADHD, astrocyte function is insufficient, particularly in terms of its formation and supply of lactate. This insufficiency has implications both for performance and development: H1 In rapidly firing neurons there is deficient ATP production, slow restoration of ionic gradients across neuronal membranes and delayed neuronal firing; H2 In oligodendrocytes insufficient lactate supply impairs fatty acid synthesis and myelination of axons during development. These effects occur over vastly different time scales: those due to deficient ATP (H1 occur over milliseconds, whereas those due to deficient myelination (H2 occur over months and years. Collectively the neural outcomes of impaired astrocytic release of lactate manifest behaviourally as inefficient and inconsistent performance (variable response times across the lifespan, especially during activities that require sustained speeded responses and complex information processing. Testing the hypothesis Multi-level and multi-method approaches are required. These include

  12. Modelling and Simulation of the Dynamics of the Antigen-Specific T Cell Response Using Variable Structure Control Theory.

    Science.gov (United States)

    Anelone, Anet J N; Spurgeon, Sarah K

    2016-01-01

    Experimental and mathematical studies in immunology have revealed that the dynamics of the programmed T cell response to vigorous infection can be conveniently modelled using a sigmoidal or a discontinuous immune response function. This paper hypothesizes strong synergies between this existing work and the dynamical behaviour of engineering systems with a variable structure control (VSC) law. These findings motivate the interpretation of the immune system as a variable structure control system. It is shown that dynamical properties as well as conditions to analytically assess the transition from health to disease can be developed for the specific T cell response from the theory of variable structure control. In particular, it is shown that the robustness properties of the specific T cell response as observed in experiments can be explained analytically using a VSC perspective. Further, the predictive capacity of the VSC framework to determine the T cell help required to overcome chronic Lymphocytic Choriomeningitis Virus (LCMV) infection is demonstrated. The findings demonstrate that studying the immune system using variable structure control theory provides a new framework for evaluating immunological dynamics and experimental observations. A modelling and simulation tool results with predictive capacity to determine how to modify the immune response to achieve healthy outcomes which may have application in drug development and vaccine design.

  13. Reliability analysis for aeroengine turbine disc fatigue life with multiple random variables based on distributed collaborative response surface method

    Institute of Scientific and Technical Information of China (English)

    高海峰; 白广忱; 高阳; 鲍天未

    2015-01-01

    The fatigue life of aeroengine turbine disc presents great dispersion due to the randomness of the basic variables, such as applied load, working temperature, geometrical dimensions and material properties. In order to ameliorate reliability analysis efficiency without loss of reliability, the distributed collaborative response surface method (DCRSM) was proposed, and its basic theories were established in this work. Considering the failure dependency among the failure modes, the distributed response surface was constructed to establish the relationship between the failure mode and the relevant random variables. Then, the failure modes were considered as the random variables of system response to obtain the distributed collaborative response surface model based on structure failure criterion. Finally, the given turbine disc structure was employed to illustrate the feasibility and validity of the presented method. Through the comparison of DCRSM, Monte Carlo method (MCM) and the traditional response surface method (RSM), the results show that the computational precision for DCRSM is more consistent with MCM than RSM, while DCRSM needs far less computing time than MCM and RSM under the same simulation conditions. Thus, DCRSM is demonstrated to be a feasible and valid approach for improving the computational efficiency of reliability analysis for aeroengine turbine disc fatigue life with multiple random variables, and has great potential value for the complicated mechanical structure with multi-component and multi-failure mode.

  14. Using climate response functions in analyzing electricity production variables. A case study from Norway.

    Science.gov (United States)

    Tøfte, Lena S.; Martino, Sara; Mo, Birger

    2016-04-01

    representation of hydropower is included and total hydro power production for each area is calculated, and the production is distributed among all available plants within each area. During simulation, the demand is affected by prices and temperatures. 6 different infrastructure scenarios of wind and power line development are analyzed. The analyses are done by running EMPS calibrated for today's situation for 11*11*8 different combinations of altered weather variables (temperature, precipitation and wind) describing different climate change scenarios, finding the climate response function for every EMPS-variable according the electricity production, such as prices and income, energy balances (supply, consumption and trade), overflow losses, probability of curtailment etc .

  15. Carbon dioxide exchange in three tundra sites show a dissimilar response to environmental variables

    DEFF Research Database (Denmark)

    Mbufong, Herbert Njuabe; Lund, Magnus; Christensen, Torben Røjle

    2015-01-01

    variability. An improved understanding of the control of ancillary variables on net ecosystem exchange (NEE), gross primary production (GPP) and ecosystem respiration (Re) will improve the accuracy with which CO2 exchange seasonality in Arctic tundra ecosystems is modelled. Fluxes were measured with the eddy...... Lake. Growing season NEE correlated mainly to cumulative radiation and temperature-related variables at Zackenberg, while at Daring Lake the same variables showed significant correlations with the partitioned fluxes (GPP and Re). Stordalen was temperature dependent during the growing season. This study...... emphasizes the inherent need for a standardized year round measurement and analytical routine of CO2 fluxes and ancillary variables, and investigations into the interconnectedness of ancillary variables in the Arctic tundra....

  16. Microbial biosurfactants and biodegradation.

    Science.gov (United States)

    Ward, Owen P

    2010-01-01

    Microbial biosurfactants are amphipathic molecules having typical molecular weights of 500-1500 Da, made up of peptides, saccharides or lipids or their combinations. In biodegradation processes they mediate solubilisation, mobilization and/or accession of hydrophobic substrates to microbes. They may be located on the cell surface or be secreted into the extracellular medium and they facilitate uptake of hydrophobic molecules through direct cellular contact with hydrophobic solids or droplets or through micellarisation. They are also involved in cell physiological processes such as biofilm formation and detachment, and in diverse biofilm associated processes such as wastewater treatment and microbial pathogenesis. The protection of contaminants in biosurfactants micelles may also inhibit uptake of contaminants by microbes. In bioremediation processes biosurfactants may facilitate release of contaminants from soil, but soils also tend to bind surfactants strongly which makes their role in contaminant desorption more complex. A greater understanding of the underlying roles played by biosurfactants in microbial physiology and in biodegradative processes is developing through advances in cell and molecular biology.

  17. Coccolithophore responses to environmental variability in the South China Sea: species composition and calcite content

    Science.gov (United States)

    Jin, Xiaobo; Liu, Chuanlian; Poulton, Alex J.; Dai, Minhan; Guo, Xianghui

    2016-08-01

    Coccolithophore contributions to the global marine carbon cycle are regulated by the calcite content of their scales (coccoliths) and the relative cellular levels of photosynthesis and calcification rates. All three of these factors vary between coccolithophore species and with response to the growth environment. Here, water samples were collected in the northern basin of the South China Sea (SCS) during summer 2014 in order to examine how environmental variability influenced species composition and cellular levels of calcite content. Average coccolithophore abundance and their calcite concentration in the water column were 11.82 cells mL-1 and 1508.3 pg C mL-1, respectively, during the cruise. Water samples can be divided into three floral groups according to their distinct coccolithophore communities. The vertical structure of the coccolithophore community in the water column was controlled by the trophic conditions, which were regulated by mesoscale eddies across the SCS basin. The evaluation of coccolithophore-based calcite in the surface ocean also showed that three key species in the SCS (Emiliania huxleyi, Gephyrocapsa oceanica, Florisphaera profunda) and other larger, numerically rare species made almost equal contributions to total coccolith-based calcite in the water column. For Emiliania huxleyi biometry measurements, coccolith size positively correlated with nutrients (nitrate, phosphate), and it is suggested that coccolith length is influenced by light and nutrients through the regulation of growth rates. Larger-sized coccoliths were also linked statistically to low pH and calcite saturation states; however, it is not a simple cause and effect relationship, as carbonate chemistry was strongly co-correlated with the other key environmental factors (nutrients, light).

  18. Loss of lag-response curvilinearity of indices of heart rate variability in congestive heart failure

    Directory of Open Access Journals (Sweden)

    Smith Michael L

    2006-06-01

    Full Text Available Abstract Background Heart rate variability (HRV is known to be impaired in patients with congestive heart failure (CHF. Time-domain analysis of ECG signals traditionally relies heavily on linear indices of an essentially non-linear phenomenon. Poincaré plots are commonly used to study non-linear behavior of physiologic signals. Lagged Poincaré plots incorporate autocovariance information and analysis of Poincaré plots for various lags can provide interesting insights into the autonomic control of the heart. Methods Using Poincaré plot analysis, we assessed whether the relation of the lag between heart beats and HRV is altered in CHF. We studied the influence of lag on estimates of Poincaré plot indices for various lengths of beat sequence in a public domain data set (PhysioNet of 29 subjects with CHF and 54 subjects with normal sinus rhythm. Results A curvilinear association was observed between lag and Poincaré plot indices (SD1, SD2, SDLD and SD1/SD2 ratio in normal subjects even for a small sequence of 50 beats (p value for quadratic term 3 × 10-5, 0.002, 3.5 × 10-5 and 0.0003, respectively. This curvilinearity was lost in patients with CHF even after exploring sequences up to 50,000 beats (p values for quadratic term > 0.5. Conclusion Since lagged Poincaré plots incorporate autocovariance information, these analyses provide insights into the autonomic control of heart rate that is influenced by the non-linearity of the signal. The differences in lag-response in CHF patients and normal subjects exist even in the face of the treatment received by the CHF patients.

  19. Exploring the climate response to the 1815 Tambora eruption with respect to natural climate variability

    Science.gov (United States)

    Lorenz, Stephan J.; Timmreck, Claudia; Jungclaus, Johann H.

    2010-05-01

    The largest historic volcanic eruption with known origin was the explosion of Mount Tambora in Indonesia in April 1815. In the aftermath of this devastating eruption, the following year 1816 came to be known as the "year without a summer", in particular in USA, Canada, and Europe, where the worst famine over a century as well as typhus epidemics accompanied by enhanced emigration from Europe were recorded. The stratospheric aerosol mass load was estimated to be about three times that of the Pinatubo eruption in 1991, leading to strong impact on the Earth's climate system. In a series of ensemble simulations of the last Millennium we applied our Earth system model, based on the ECHAM5/MPIOM model family, to investigate the climate signal of the Tambora eruption with respect to natural and forced variability. This event contributed to one of the strongest cooling periods during the last Millennium in the ensemble of simulations. However, this period is associated with a large ensemble spread in simulated air temperature on a hemispheric and global as well as on a regional scale, with limited to very strong atmospheric response. The unique path of the climate evolution through the Earth's history yielding the extreme summer in 1816 in North America and Europe is compared with the simulations. A special focus of our analysis is Tambora's impact on climate and its relationship with the status of the climate system, e.g. the ENSO state, at the time of the eruption. Additionally, the contribution of the large volcanic eruption with tropical but unknown location about six years prior to the Tambora in 1809 will be discussed.

  20. Variability in cell response of Cronobacter sakazakii after mild-heat treatments and its impact on food safety

    Science.gov (United States)

    Cronobacter spp. have been responsible for severe infections in infants associated with consumption of powdered infant formula (PIF) and follow-up formulae (FUF). Despite several risk assessments described in published studies, few approaches have considered the tremendous variability in cell respo...

  1. Intratesticular and subcutaneous lidocaine alters the intraoperative haemodynamic responses and heart rate variability in male cats undergoing castration

    NARCIS (Netherlands)

    Moldal, E.R.; Eriksen, T.; Kirpensteijn, J.; Nødtvedt, A.; Kristensen, A.T.; Sparta, F.M.; Haga, H.A.

    2013-01-01

    Abstract OBJECTIVE: To evaluate the usefulness of intratesticular and subcutaneous lidocaine in alleviating the intraoperative nociceptive response to castration, measured by pulse rate (PR) and mean arterial pressure (MAP), and to test the applicability of heart rate variability (HRV) analysis in a

  2. Streamflow response to climate variability and human activities in the upper catchment of the Yellow River Basin

    Institute of Scientific and Technical Information of China (English)

    ZHAO FangFang; XU ZongXue; ZHANG Lu; ZUO DePeng

    2009-01-01

    Both sensitivity-based method and simulation method are used to analyze the streamflow response to climate variability and human activities in the upper catchment of the Yellow River Basin (UYRB) in this study.The separation regime of effects from climate variability and human activities is investigated.Results show that the changes of streamflow are more sensitive to precipitation than potential evapotranspiration (PET).Effect of climate variability on streamflow estimated using the sensitiv-ity-based method is weak in the upper catchment of Jimai station, and strong in the upper catchment of Lanzhou station, where the climate effects accounted for about 50% of total streamflow changes.Effects of human activities on streamflow accounted for about 40% in the UYRB, with weaker effects in the upper catchment of Tangnaihai station than those in the upper catchment of Lanzhou station.Both climate variability and human activities are main factors to affect the changes of streamflow in the UYRB.

  3. Streamflow response to climate variability and human activities in the upper catchment of the Yellow River Basin

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Both sensitivity-based method and simulation method are used to analyze the streamflow response to climate variability and human activities in the upper catchment of the Yellow River Basin (UYRB) in this study. The separation regime of effects from climate variability and human activities is investigated. Results show that the changes of streamflow are more sensitive to precipitation than potential evapotranspiration (PET). Effect of climate variability on streamflow estimated using the sensitivity-based method is weak in the upper catchment of Jimai station, and strong in the upper catchment of Lanzhou station, where the climate effects accounted for about 50% of total streamflow changes. Effects of human activities on streamflow accounted for about 40% in the UYRB, with weaker effects in the upper catchment of Tangnaihai station than those in the upper catchment of Lanzhou station. Both climate variability and human activities are main factors to affect the changes of streamflow in the UYRB.

  4. Vegetation Responses to Climate Variability in the Northern Arid to Sub-Humid Zones of Sub-Saharan Africa

    Directory of Open Access Journals (Sweden)

    Khaldoun Rishmawi

    2016-11-01

    Full Text Available In water limited environments precipitation is often considered the key factor influencing vegetation growth and rates of development. However; other climate variables including temperature; humidity; the frequency and intensity of precipitation events are also known to affect productivity; either directly by changing photosynthesis and transpiration rates or indirectly by influencing water availability and plant physiology. The aim here is to quantify the spatiotemporal patterns of vegetation responses to precipitation and to additional; relevant; meteorological variables. First; an empirical; statistical analysis of the relationship between precipitation and the additional meteorological variables and a proxy of vegetation productivity (the Normalized Difference Vegetation Index; NDVI is reported and; second; a process-oriented modeling approach to explore the hydrologic and biophysical mechanisms to which the significant empirical relationships might be attributed. The analysis was conducted in Sub-Saharan Africa; between 5 and 18°N; for a 25-year period 1982–2006; and used a new quasi-daily Advanced Very High Resolution Radiometer (AVHRR dataset. The results suggest that vegetation; particularly in the wetter areas; does not always respond directly and proportionately to precipitation variation; either because of the non-linearity of soil moisture recharge in response to increases in precipitation; or because variations in temperature and humidity attenuate the vegetation responses to changes in water availability. We also find that productivity; independent of changes in total precipitation; is responsive to intra-annual precipitation variation. A significant consequence is that the degree of correlation of all the meteorological variables with productivity varies geographically; so no one formulation is adequate for the entire region. Put together; these results demonstrate that vegetation responses to meteorological variation are more

  5. Temporal variability in California grasslands: soil type and species functional traits mediate response to precipitation.

    Science.gov (United States)

    Fernandez-Going, B M; Anacker, B L; Harrison, S P

    2012-09-01

    Plant communities on infertile soils may be relatively resistant to climatic variation if species in these communities have "stress-tolerant" functional traits that limit their ability to respond to climate. Alternatively, such communities may be more sensitive to climatic variation if their relatively sparse vegetative cover exposes species to more extreme changes in factors such as temperature or wind. We compared temporal variability in species richness and composition over 10 years between grasslands on infertile serpentine and "normal" sedimentary soils. Variability in species richness and species composition tracked mean annual precipitation on both soils, but variability was lower in serpentine grasslands. Communities on serpentine had lower functional diversity and had species with more "stress-tolerant" traits than non-serpentine communities (i.e., shorter stature, lower specific leaf area, and lower leaf area). Within and between soils, variability in species richness and temporal turnover were lower in communities scoring as more stress tolerant on a multivariate index of these traits; however, community variability was unrelated to functional diversity. Within 41 species found commonly on both soils, variability in occurrence and cover were also lower on serpentine soils, even though intraspecific trait differences between soils were minimal; this suggests a direct effect of soil type on species variability in addition to the indirect, trait-mediated effect. Communities with higher biomass had higher annual variability in species occurrence and cover. Our results suggest that infertile soils reduce compositional variability indirectly by selecting for stress-tolerant traits and directly by limiting productivity. We conclude that communities on infertile soils may respond more conservatively to predicted changes in precipitation, including increased variability, than communities on soils of normal fertility.

  6. Water-curable and biodegradable prepolymers.

    Science.gov (United States)

    Kobayashi, H; Hyon, S H; Ikada, Y

    1991-12-01

    In an attempt to develop biodegradable polymers which can be shaped in situ and adhere to living tissues, we synthesized esterurethane prepolymers which can be cured upon contact with water in living tissues. First, D,L-lactide polymerization or D,L-lactide-epsilon-caprolactone (50:50) copolymerization was carried out using ethylene glycol or poly(ethylene glycol) as initiator to obtain hydroxyl-terminated biodegradable polyesters. They were then reacted with an excess of diisocyanate such as hexamethylene diisocyanate, toluylene diisocyanate, and diphenylmethane diisocyanate to introduce a reactive isocyanate group to both of the end groups of the polyesters. The isocyanate-terminated prepolymers could be cured in the presence of water and the cured polymers were degraded by hydrolysis both in vitro and in vivo. It was found that the presence of appropriate amounts of hydrophilic units in the main chain was essential for giving a high curing rate and a high degradation rate for the biodegradable urethane prepolymers. The tissue responses to the cured polymers were not severe.

  7. Biodegradation of Polypropylene Nonwovens

    Science.gov (United States)

    Keene, Brandi Nechelle

    The primary aim of the current research is to document the biodegradation of polypropylene nonwovens and filament under composting environments. To accelerate the biodegradat ion, pre-treatments and additives were incorporated into polypropylene filaments and nonwovens. The initial phase (Chapter 2) of the project studied the biodegradation of untreated polypropylene with/without pro-oxidants in two types of composting systems. Normal composting, which involved incubation of samples in food waste, had little effect on the mechanical properties of additive-free spunbond nonwovens in to comparison prooxidant containing spunbond nonwovens which were affected significantly. Modified composting which includes the burial of samples with food and compressed air, the polypropylene spunbond nonwovens with/without pro-oxidants displayed an extreme loss in mechanical properties and cracking on the surface cracking. Because the untreated spunbond nonwovens did not completely decompose, the next phase of the project examined the pre-treatment of gamma-irradiation or thermal aging prior to composting. After exposure to gamma-irradiation and thermal aging, polypropylene is subjected to oxidative degradation in the presence of air and during storage after irradiat ion. Similar to photo-oxidation, the mechanism of gamma radiation and thermal oxidative degradation is fundamentally free radical in nature. In Chapter 3, the compostability of thermal aged spunbond polypropylene nonwovens with/without pro-oxidant additives. The FTIR spectrum confirmed oxidat ion of the polypropylene nonwovens with/without additives. Cracking on both the pro-oxidant and control spunbond nonwovens was showed by SEM imaging. Spunbond polypropylene nonwovens with/without pro-oxidants were also preirradiated by gamma rays followed by composting. Nonwovens with/without pro-oxidants were severely degraded by gamma-irradiation after up to 20 kGy exposure as explained in Chapter 4. Furthermore (Chapter 5), gamma

  8. Biodegradable plastics from renewable sources.

    Science.gov (United States)

    Flieger, M; Kantorová, M; Prell, A; Rezanka, T; Votruba, J

    2003-01-01

    Plastic waste disposal is a huge ecotechnological problem and one of the approaches to solving this problem is the development of biodegradable plastics. This review summarizes data on their use, biodegradability, commercial reliability and production from renewable resources. Some commercially successful biodegradable plastics are based on chemical synthesis (i.e. polyglycolic acid, polylactic acid, polycaprolactone, and polyvinyl alcohol). Others are products of microbial fermentations (i.e. polyesters and neutral polysaccharides) or are prepared from chemically modified natural products (e.g., starch, cellulose, chitin or soy protein).

  9. Response of the mean global vegetation distribution to interannual climate variability

    Energy Technology Data Exchange (ETDEWEB)

    Notaro, Michael [University of Wisconsin-Madison, Center for Climatic Research, Madison, WI (United States)

    2008-06-15

    The impact of interannual variability in temperature and precipitation on global terrestrial ecosystems is investigated using a dynamic global vegetation model driven by gridded climate observations for the twentieth century. Contrasting simulations are driven either by repeated mean climatology or raw climate data with interannual variability included. Interannual climate variability reduces net global vegetation cover, particularly over semi-arid regions, and favors the expansion of grass cover at the expense of tree cover, due to differences in growth rates, fire impacts, and interception. The area burnt by global fires is substantially enhanced by interannual precipitation variability. The current position of the central United States' ecotone, with forests to the east and grasslands to the west, is largely attributed to climate variability. Among woody vegetation, climate variability supports expanded deciduous forest growth and diminished evergreen forest growth, due to difference in bioclimatic limits, leaf longevity, interception rates, and rooting depth. These results offer insight into future ecosystem distributions since climate models generally predict an increase in climate variability and extremes. (orig.)

  10. VARIABILITY OF NEURONAL RESPONSES: TYPES AND FUNCTIONAL SIGNIFICANCE IN NEUROPLASTICITY AND NEURAL DARWINISM

    Directory of Open Access Journals (Sweden)

    Alexander Chervyakov

    2016-11-01

    Full Text Available In many cases, neural signals detected under the same external experimental conditions significantly change from trial to trial. The variability phenomenon, which complicates extraction of reproducible results and is ignored in many studies by averaging, has attracted attention of researchers in recent years. In this paper, we classify possible types of variability based on its functional significance and describe features of each type. We describe the key adaptive significance of variability at the neural network level and the degeneracy phenomenon that may be important for learning processes in connection with the principle of neuronal group selection.

  11. Biodegradable micromechanical sensors

    DEFF Research Database (Denmark)

    Keller, Stephan Sylvest; Greve, Anders; Schmid, Silvan

    The development of biopolymers for food packaging, medical engineering or drug delivery is a growing field of research [1]. At the same time, the interest in methods for detailed analysis of biopolymers is increasing. Micromechanical sensors are versatile tools for the characterization of mechani......The development of biopolymers for food packaging, medical engineering or drug delivery is a growing field of research [1]. At the same time, the interest in methods for detailed analysis of biopolymers is increasing. Micromechanical sensors are versatile tools for the characterization...... of biopolymers to microfabrication is challenging, as these polymers are affected by common processes such as photolithography or wet etching. Here, we present two methods for fabrication of biodegradable micromechanical sensors. First, we fabricated bulk biopolymer microcantilevers using nanoimprint lithography...

  12. Biodegradation of propellant ingredients

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Y.Z.; Sundaram, S.T.; Sharma, A. [Geo-centers, Inc., Lake Hopatcong, NJ (United States)] [and others

    1995-12-31

    This paper summarizes efforts to degrade nitrocellulose (NC) and nitroglycerin (NG) with fungi. Screening experiments were performed to determine the ability of mycelial fungi to biodegrade NC. The greatest amount of NC degradation was obtained with Sclerotium rolfsii ATCC 24459 and Fusarium solani IFO 31093. These fungi were then tested for NG degradation. It was found that the combined culture aerobically degraded 100% of the NG to form a mixture of 55% dinitroglycerin (DNG) and 5% of mononitroglycerin (MNG) in two days, with no further change observed afterward. In the presence of 1.2% glucose and 0.05% ammonium nitrate, NG was completely degraded in two days and a mixture of 20% DNG and 16% MNG was formed after 11 days. Based on these results, it appears that the combination of the fungi in a one to one ratio can be used to degrade both of these energetic compounds.

  13. Compared in vivo toxicity in mice of lung delivered biodegradable and non-biodegradable nanoparticles.

    Science.gov (United States)

    Aragao-Santiago, Letícia; Hillaireau, Hervé; Grabowski, Nadège; Mura, Simona; Nascimento, Thais L; Dufort, Sandrine; Coll, Jean-Luc; Tsapis, Nicolas; Fattal, Elias

    2016-01-01

    To design nanoparticle (NP)-based drug delivery systems for pulmonary administration, biodegradable materials are considered safe, but their potential toxicity is poorly explored. We here explore the lung toxicity in mice of biodegradable nanoparticles (NPs) and compare it to the toxicity of non-biodegradable ones. NP formulations of poly(d,l-lactide-co-glycolide) (PLGA) coated with chitosan (CS), poloxamer 188 (PF68) or poly(vinyl alcohol) (PVA), which renders 200 nm NPs of positive, negative or neutral surface charge respectively, were analyzed for their biodistribution by in vivo fluorescence imaging and their inflammatory potential after single lung nebulization in mice. After exposure, analysis of bronchoalveolar lavage (BAL) cell population, protein secretion and cytokine release as well as lung histology were carried out. The inflammatory response was compared to the one induced by non-biodegradable counterparts, namely, TiO2 of rutile and anatase crystal form and polystyrene (PS). PLGA NPs were mostly present in mice lungs, with little passage to other organs. An increase in neutrophil recruitment was observed in mice exposed to PS NPs 24 h after nebulization, which declined at 48 h. This result was supported by an increase in interleukin (IL)-6 and tumor necrosis factor α (TNFα) in BAL supernatant at 24 h. TiO2 anatase NPs were still present in lung cells 48 h after nebulization and induced the expression of pro-inflammatory cytokines and the recruitment of polymorphonuclear cells to BAL. In contrast, regardless of their surface charge, PLGA NPs did not induce significant changes in the inflammation markers analyzed. In conclusion, these results point out to a safe use of PLGA NPs regardless of their surface coating compared to non-biodegradable ones.

  14. Variability in Cell Response of Cronobacter sakazakii after Mild-Heat Treatments and Its Impact on Food Safety

    Science.gov (United States)

    Parra-Flores, Julio; Juneja, Vijay; Garcia de Fernando, Gonzalo; Aguirre, Juan

    2016-01-01

    Cronobacter spp. have been responsible for severe infections in infants associated with consumption of powdered infant formula and follow-up formulae. Despite several risk assessments described in published studies, few approaches have considered the tremendous variability in cell response that small micropopulations or single cells can have in infant formula during storage, preparation or post process/preparation before the feeding of infants. Stochastic approaches can better describe microbial single cell response than deterministic models as we prove in this study. A large variability of lag phase was observed in single cell and micropopulations of ≤50 cells. This variability increased as the heat shock increased and growth temperature decreased. Obviously, variability of growth of individual Cronobacter sakazakii cell is affected by inoculum size, growth temperature and the probability of cells able to grow at the conditions imposed by the experimental conditions should be taken into account, especially when errors in bottle-preparation practices, such as improper holding temperatures, or manipulation, may lead to growth of the pathogen to a critical cell level. The mean probability of illness from initial inoculum size of 1 cell was below 0.2 in all the cases and for inoculum size of 50 cells the mean probability of illness, in most of the cases, was above 0.7. PMID:27148223

  15. Variability in cell response of Cronobacter sakazakii after mild-heat treatments and its impact on food safety

    Directory of Open Access Journals (Sweden)

    Julio eParra-Flores

    2016-04-01

    Full Text Available Cronobacter spp. have been responsible for severe infections in infants associated with consumption of powdered infant formula (PIF and follow-up formulae (FUF. Despite several risk assessments described in published studies, few approaches have considered the tremendous variability in cell response that small micropopulations or single cells can have in infant formula during storage, preparation or post process/preparation before the feeding of infants. Stochastic approaches can better describe microbial single cell response than deterministic models as we prove in this study. A large variability of lag phase was observed in single cell and micropopulations of ≤50 cells. This variability increased as the heat shock increased and growth temperature decreased. Obviously, variability of growth of individual Cronobacter sakazakii cell is affected by inoculum size, growth temperature and the probability of cells able to grow at the conditions imposed by the experimental conditions should be taken into account, especially when errors in bottle-preparation practices, such as improper holding temperatures or manipulation, may lead to growth of the pathogen to a critical cell level. The mean probability of illness from initial inoculum size of 1 cell were below 0.2 in all the cases and for inoculum size of 50 cells the mean probability of illness were, in most of the cases, was above 0.7.

  16. The relationship between environmental variables and response of cotton to nematicides.

    Science.gov (United States)

    Wheeler, T A; Lawrence, K S; Porter, D O; Keeling, W; Mullinix, B G

    2013-03-01

    Nematicide/irrigation rate trials were conducted in Texas (TX) in 2009 and 2010 in cotton grown at three irrigation rates, where irrigation rate (base (B), B - 33%, B + 33%) was the main plot and treatment (untreated check, aldicarb, and nematicide seed treatment (NST) and NST + aldicarb) were the subplots. Aldicarb improved cotton lint yield with the base (medium) irrigation rate over the untreated check, but not at the B - 33% and B + 33% irrigation rates. In a second evaluation, 20 tests conducted over 7 yr at the same field in TX and 12 tests conducted over 6 yr at the same field in Alabama (AL) were examined for impact of environmental variables (EV) on the response to NST (containing thiodicarb or abamectin), aldicarb, a nontreated check (CK), insecticide seed treatment (TX only), and a combination of NST + aldicarb + oxamyl (NST/A/O, AL only) on root galls (TX only), early season nematode eggs (AL only), and yield (both sites). Galls/root system were lower with aldicarb-treated plots, than for the CK- or NST-treated plots. As water (irrigation plus rain) in May increased, galls/root system increased for CK or insecticide-only-treated plots, and decreased for NST- and aldicarb-treated plots, suggesting efficacy of nematicides was strongly improved by adequate soil moisture. Nematode reproduction was not affected by EV in either location, though yield was negatively affected by root-knot nematode eggs in AL at 60 d. Yield in both AL and TX was negatively related to temperature parameters and positively related to water parameters. With the addition of EV in TX, chemical treatments went from not significantly different in the absence of EV to aldicarb-treated plots having higher yields than nonnematicide-treated plots in the presence of EV. In AL, NST/A/O-treated plots yielded similar to aldicarb and better than CK or NST in the absence of EV and had significantly higher yields than all other treatments in the presence of most EV.

  17. Peak expiratory flow variability, bronchial responsiveness, and susceptibility to ambient air pollution in adults

    NARCIS (Netherlands)

    Boezen, M; Schouten, Jan; Rijcken, B; Vonk, J; Gerritsen, J; Hoek, G; Brunekreef, B; Postma, D

    1998-01-01

    Bronchial hyperresponsiveness (BHR) and peak expiratory flow (PEF) variability are associated expressions of airway lability, yet probably reflect different underlying pathophysiologic mechanisms. We investigated whether both measures can be used interchangeably to identify subjects who are suscepti

  18. Lab-scale experimental strategy for determining micropollutant partition coefficient and biodegradation constants in activated sludge.

    Science.gov (United States)

    Pomiès, M; Choubert, J M; Wisniewski, C; Miège, C; Budzinski, H; Coquery, M

    2015-03-01

    The nitrifying/denitrifying activated sludge process removes several micropollutants from wastewater by sorption onto sludge and/or biodegradation. The objective of this paper is to propose and evaluate a lab-scale experimental strategy for the determination of partition coefficient and biodegradation constant for micropollutant with an objective of modelling their removal. Four pharmaceutical compounds (ibuprofen, atenolol, diclofenac and fluoxetine) covering a wide hydrophobicity range (log Kow from 0.16 to 4.51) were chosen. Dissolved and particulate concentrations were monitored for 4 days, inside two reactors working under aerobic and anoxic conditions, and under different substrate feed conditions (biodegradable carbon and nitrogen). We determined the mechanisms responsible for the removal of the target compounds: (i) ibuprofen was biodegraded, mainly under aerobic conditions by cometabolism with biodegradable carbon, whereas anoxic conditions suppressed biodegradation; (ii) atenolol was biodegraded under both aerobic and anoxic conditions (with a higher biodegradation rate under aerobic conditions), and cometabolism with biodegradable carbon was the main mechanism; (iii) diclofenac and fluoxetine were removed by sorption only. Finally, the abilities of our strategy were evaluated by testing the suitability of the parameters for simulating effluent concentrations and removal efficiency at a full-scale plant.

  19. Performance of PLS regression coefficients in selecting variables for each response of a multivariate PLS for omics-type data

    Directory of Open Access Journals (Sweden)

    Giuseppe Palermo

    2009-05-01

    Full Text Available Giuseppe Palermo1, Paolo Piraino2, Hans-Dieter Zucht31Digilab BioVision GmbH, Hannover, Germany; 2Dr Paolo Piraino Statistical Consulting, Rende (CS, Italy; 3Proteome Sciences R&D GmbH and C. KG, Frankfurt am Main, GermanyAbstract: Multivariate partial least square (PLS regression allows the modeling of complex biological events, by considering different factors at the same time. It is unaffected by data collinearity, representing a valuable method for modeling high-dimensional biological data (as derived from genomics, proteomics and peptidomics. In presence of multiple responses, it is of particular interest how to appropriately “dissect” the model, to reveal the importance of single attributes with regard to individual responses (for example, variable selection. In this paper, performances of multivariate PLS regression coefficients, in selecting relevant predictors for different responses in omics-type of data, were investigated by means of a receiver operating characteristic (ROC analysis. For this purpose, simulated data, mimicking the covariance structures of microarray and liquid chromatography mass spectrometric data, were used to generate matrices of predictors and responses. The relevant predictors were set a priori. The influences of noise, the source of data with different covariance structure and the size of relevant predictors were investigated. Results demonstrate the applicability of PLS regression coeffi cients in selecting variables for each response of a multivariate PLS, in omics-type of data. Comparisons with other feature selection methods, such as variable importance in the projection scores, principal component regression, and least absolute shrinkage and selection operator regression were also provided.Keywords: partial least square regression, regression coefficients, variable selection, biomarker discovery, omics-data

  20. Biomedical Applications of Biodegradable Polyesters

    OpenAIRE

    Iman Manavitehrani; Ali Fathi; Hesham Badr; Sean Daly; Ali Negahi Shirazi; Fariba Dehghani

    2016-01-01

    The focus in the field of biomedical engineering has shifted in recent years to biodegradable polymers and, in particular, polyesters. Dozens of polyester-based medical devices are commercially available, and every year more are introduced to the market. The mechanical performance and wide range of biodegradation properties of this class of polymers allow for high degrees of selectivity for targeted clinical applications. Recent research endeavors to expand the application of polymers have be...

  1. Effects of head-down bed rest on complex heart rate variability: Response to LBNP testing

    Science.gov (United States)

    Goldberger, Ary L.; Mietus, Joseph E.; Rigney, David R.; Wood, Margie L.; Fortney, Suzanne M.

    1994-01-01

    Head-down bed rest is used to model physiological changes during spaceflight. We postulated that bed rest would decrease the degree of complex physiological heart rate variability. We analyzed continuous heart rate data from digitized Holter recordings in eight healthy female volunteers (age 28-34 yr) who underwent a 13-day 6 deg head-down bed rest study with serial lower body negative pressure (LBNP) trials. Heart rate variability was measured on a 4-min data sets using conventional time and frequency domain measures as well as with a new measure of signal 'complexity' (approximate entropy). Data were obtained pre-bed rest (control), during bed rest (day 4 and day 9 or 11), and 2 days post-bed rest (recovery). Tolerance to LBNP was significantly reduced on both bed rest days vs. pre-bed rest. Heart rate variability was assessed at peak LBNP. Heart rate approximate entropy was significantly decreased at day 4 and day 9 or 11, returning toward normal during recovery. Heart rate standard deviation and the ratio of high- to low-power frequency did not change significantly. We conclude that short-term bed rest is associated with a decrease in the complex variability of heart rate during LBNP testing in healthy young adult women. Measurement of heart rate complexity, using a method derived from nonlinear dynamics ('chaos theory'), may provide a sensitive marker of this loss of physiological variability, complementing conventional time and frequency domain statistical measures.

  2. A radiobiological model of radiotherapy response and its correlation with prognostic imaging variables

    Science.gov (United States)

    Crispin-Ortuzar, Mireia; Jeong, Jeho; Fontanella, Andrew N.; Deasy, Joseph O.

    2017-04-01

    Radiobiological models of tumour control probability (TCP) can be personalized using imaging data. We propose an extension to a voxel-level radiobiological TCP model in order to describe patient-specific differences and intra-tumour heterogeneity. In the proposed model, tumour shrinkage is described by means of a novel kinetic Monte Carlo method for inter-voxel cell migration and tumour deformation. The model captures the spatiotemporal evolution of the tumour at the voxel level, and is designed to take imaging data as input. To test the performance of the model, three image-derived variables found to be predictive of outcome in the literature have been identified and calculated using the model’s own parameters. Simulating multiple tumours with different initial conditions makes it possible to perform an in silico study of the correlation of these variables with the dose for 50% tumour control (\\text{TC}{{\\text{D}}50} ) calculated by the model. We find that the three simulated variables correlate with the calculated \\text{TC}{{\\text{D}}50} . In addition, we find that different variables have different levels of sensitivity to the spatial distribution of hypoxia within the tumour, as well as to the dynamics of the migration mechanism. Finally, based on our results, we observe that an adequate combination of the variables may potentially result in higher predictive power.

  3. Variability of North Sea pH and CO2 in response to North Atlantic Oscillation forcing

    DEFF Research Database (Denmark)

    Salt, Lesley A.; Thomas, Helmuth; Prowe, Friederike;

    2013-01-01

    observational records covering the relevant levels of the NAO index, we provide evidence that the North Sea pH and CO2 system strongly responds to external and internal expressions of the NAO. Under positive NAO, the higher rates of inflow of water from the North Atlantic Ocean and the Baltic outflow lead......[1] High biological activity causes a distinct seasonality of surface water pH in the North Sea, which is a strong sink for atmospheric CO2 via an effective shelf pump. The intimate connection between the North Sea and the North Atlantic Ocean suggests that the variability of the CO2 system...... of the North Atlantic Ocean may, in part, be responsible for the observed variability of pH and CO2 in the North Sea. In this work, we demonstrate the role of the North Atlantic Oscillation (NAO), the dominant climate mode for the North Atlantic, in governing this variability. Based on three extensive...

  4. Biodegradable intestinal stents:A review

    Institute of Scientific and Technical Information of China (English)

    Zhanhui Wang; Nan Li; Rui Li; Yawei Li; Liqun Ruan

    2014-01-01

    Biodegradable stents are an attractive alternative to self-expanding metal stents in the treatment of intestinal strictures. Biodegradable stent can be made of biodegradable polymers and biodegradable metals (magnesium alloys). An overview on current biodegradable intestinal stents is presented. The future trends and perspectives in the development of biodegradable intestinal stents are proposed. For the biodegradable polymer intestinal stents, the clinical trials have shown promising results, although improved design of stents and reduced migration rate are expected. For the biodegradable magnesium intestinal stents, results of preliminary studies indicate magnesium alloys to have good biocompatibility. With many of the key fundamental and practical issues resolved and better methods for adjusting corrosion resistance and progressing biocompatibilities of magnesium alloys, it is possible to use biodegradable intestinal stents made of magnesium alloys in hospital in the not too distant future.

  5. Adulthood stress responses in rats are variably altered as a factor of adolescent stress exposure.

    Science.gov (United States)

    Moore, Nicole L T; Altman, Daniel E; Gauchan, Sangeeta; Genovese, Raymond F

    2016-05-01

    Stress exposure during development may influence adulthood stress response severity. The present study investigates persisting effects of two adolescent stressors upon adulthood response to predator exposure (PE). Rats were exposed to underwater trauma (UWT) or PE during adolescence, then to PE after reaching adulthood. Rats were then exposed to predator odor (PO) to test responses to predator cues alone. Behavioral and neuroendocrine assessments were conducted to determine acute effects of each stress experience. Adolescent stress altered behavioral response to adulthood PE. Acoustic startle response was blunted. Bidirectional changes in plus maze exploration were revealed as a factor of adolescent stress type. Neuroendocrine response magnitude did not predict severity of adolescent or adult stress response, suggesting that different adolescent stress events may differentially alter developmental outcomes regardless of acute behavioral or neuroendocrine response. We report that exposure to two different stressors in adolescence may differentially affect stress response outcomes in adulthood. Acute response to an adolescent stressor may not be consistent across all stressors or all dependent measures, and may not predict alterations in developmental outcomes pertaining to adulthood stress exposure. Further studies are needed to characterize factors underlying long-term effects of a developmental stressor.

  6. Randomised Response Technique-An Innovative Method To Measure Culturally Sensitive Variables : Results From A Pilot Study

    Directory of Open Access Journals (Sweden)

    Soudarssanane M. B

    2003-01-01

    Full Text Available Research questions: What is the advantage of Randomized Response Technique (RRT over the conventional Direct Interview (DI and Anonymous Questionnaire (AQ in the assessment of culturally sensitive variables? Objectives: To compare the efficacy of the three methods, namely RRT, DI and AQ in the measurement of prevalence of Pre/Extra marital sex. Study design: Cross sectional study, using the three methods. Setting: A pilot study in a given community in Pondicherry. Statistical analysis: Probability equations. Results: The prevalence of pre/extra marital sex in the study population by the DI, AQ and RRT methods were 0%, 6% and 10% respectively in this pilot study. Conclusion: RRT improves validity of measurement of culturally sensitive variables both by ensuring a high participation in the study and by enabling a true response by assuring full confidentiality of information.

  7. Spatial uncoupling of biodegradation, soil respiration, and PAH concentration in a creosote contaminated soil

    Energy Technology Data Exchange (ETDEWEB)

    Bengtsson, Goeran, E-mail: goran.bengtsson@ekol.lu.s [Lund University, Department of Ecology, Soelvegatan 37, SE-223 62 Lund (Sweden); Toerneman, Niklas [Lund University, Department of Ecology, Soelvegatan 37, SE-223 62 Lund (Sweden); Yang Xiuhong [Lund University, Department of Ecology, Soelvegatan 37, SE-223 62 Lund (Sweden); Department of Environmental Science, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275 (China)

    2010-09-15

    Hotspots and coldspots of concentration and biodegradation of polycyclic aromatic hydrocarbons (PAHs) marginally overlapped at the 0.5-100 m scale in a creosote contaminated soil in southern Sweden, suggesting that concentration and biodegradation had little spatial co-variation. Biodegradation was substantial and its spatial variability considerable and highly irregular, but it had no spatial autocorrelation. The soil concentration of PAHs explained only 20-30% of the variance of their biodegradation. Soil respiration was spatially autocorrelated. The spatial uncoupling between biodegradation and soil respiration seemed to be governed by the aging of PAHs in the soil, since biodegradation of added {sup 13}C phenanthrene covaried with both soil respiration and microbial biomass. The latter two were also correlated with high concentrations of phospholipid fatty acids (PLFAs) that are common in gram-negative bacteria. However, several of the hotspots of biodegradation coincided with hotspots for the distribution of a PLFA indicative of fungal biomass. - Hotspots of PAH biodegradation in a creosote contaminated soil do not coincide with hotspots of PAH concentration, microbial biomass and respiration.

  8. Biodegradation of plastics in soil and effects on nitrification activity. A laboratory approach

    Science.gov (United States)

    Bettas Ardisson, Giulia; Tosin, Maurizio; Barbale, Marco; Degli-Innocenti, Francesco

    2014-01-01

    The progressive application of new biodegradable plastics in agriculture calls for improved testing approaches to assure their environmental safety. Full biodegradation (≥90%) prevents accumulation in soil, which is the first tier of testing. The application of specific ecotoxicity tests is the second tier of testing needed to show safety for the soil ecosystem. Soil microbial nitrification is widely used as a bioindicator for evaluating the impact of chemicals on soil but it is not applied for evaluating the impact of biodegradable plastics. In this work the International Standard test for biodegradation of plastics in soil (ISO 17556, 2012) was applied both to measure biodegradation and to prepare soil samples needed for a subsequent nitrification test based on another International Standard (ISO 14238, 2012). The plastic mulch film tested in this work showed full biodegradability and no inhibition of the nitrification potential of the soil in comparison with the controls. The laboratory approach suggested in this Technology Report enables (i) to follow the course of biodegradation, (ii) a strict control of variables and environmental conditions, (iii) the application of very high concentrations of test material (to maximize the possible effects). This testing approach could be taken into consideration in improved testing schemes aimed at defining the biodegradability of plastics in soil. PMID:25566223

  9. Biodegradation of plastics in soil and effects on nitrification activity. A laboratory approach.

    Science.gov (United States)

    Bettas Ardisson, Giulia; Tosin, Maurizio; Barbale, Marco; Degli-Innocenti, Francesco

    2014-01-01

    The progressive application of new biodegradable plastics in agriculture calls for improved testing approaches to assure their environmental safety. Full biodegradation (≥90%) prevents accumulation in soil, which is the first tier of testing. The application of specific ecotoxicity tests is the second tier of testing needed to show safety for the soil ecosystem. Soil microbial nitrification is widely used as a bioindicator for evaluating the impact of chemicals on soil but it is not applied for evaluating the impact of biodegradable plastics. In this work the International Standard test for biodegradation of plastics in soil (ISO 17556, 2012) was applied both to measure biodegradation and to prepare soil samples needed for a subsequent nitrification test based on another International Standard (ISO 14238, 2012). The plastic mulch film tested in this work showed full biodegradability and no inhibition of the nitrification potential of the soil in comparison with the controls. The laboratory approach suggested in this Technology Report enables (i) to follow the course of biodegradation, (ii) a strict control of variables and environmental conditions, (iii) the application of very high concentrations of test material (to maximize the possible effects). This testing approach could be taken into consideration in improved testing schemes aimed at defining the biodegradability of plastics in soil.

  10. Biodegradation of plastics in soil and effects on nitrification activity. A laboratory approach.

    Directory of Open Access Journals (Sweden)

    Giulia eBettas Ardisson

    2014-12-01

    Full Text Available The progressive application of new biodegradable plastics in agriculture calls for improved testing approaches to assure their environmental safety. Full biodegradation (≥ 90% prevents accumulation in soil, which is the first tier of testing. The application of specific ecotoxicity tests is the second tier of testing needed to show safety for the soil ecosystem. Soil microbial nitrification is widely used as a bioindicator for evaluating the impact of chemicals on soil but it is not applied for evaluating the impact of biodegradable plastics. In this work the International Standard test for biodegradation of plastics in soil (ISO 17556, 2012 was applied both to measure biodegradation and to prepare soil samples needed for a subsequent nitrification test based on another International Standard (ISO 14238, 2012. The plastic mulch film tested in this work showed full biodegradability and no inhibition of the nitrification potential of the soil in comparison with the controls. The laboratory approach suggested in this Technology Report enables (i to follow the course of biodegradation, (ii a strict control of variables and environmental conditions, (iii the application of very high concentrations of test material (to maximize the possible effects. This testing approach could be taken into consideration in improved testing schemes aimed at defining the biodegradability of plastics in soil.

  11. Distinguishing spatiotemporal variability of sediment sources in small urbanized catchment as a response to urban expansion

    Science.gov (United States)

    Belyaev, Vladimir; Feoktistov, Artem; Huygens, Dries; Shamshurina, Eugenia; Golosov, Valentin

    2014-05-01

    Understanding hydrological response and geomorphic behavior of small catchments in urban environments, especially those experiencing urban expansion, represents serious and important problem which has not yet been given an adequate research attention. Urbanization exerts profound and diverse impacts on catchment characteristics, particularly by increasing surface runoff coefficients, peak flow discharges and rates of flash flood waves propagation as a result of widespread appearance of buildings and paved surfaces with practically zero infiltration capacities. Another essential influence of urbanization on small catchment hydrological regimes is associated with significant changes of natural topography (from relatively minor modifications such as grading of steeper slopes to complete transformations including total filling of gullies and small valleys, transfer of small streams from surface into underground pipes or collectors, etc.) combined with creation of systems of concrete-protected surface drainages and underground storm flow sewages. Such activities can result in substantial changes of runoff- and sediment-contributing areas for the remaining gullies and small valleys in comparison to the pre-urbanization conditions, causing dramatic increase of fluvial activity in some of those and much lower flow discharges in others. In addition, gullies and small valleys in urban settlements often become sites of dumping for both dry and liquid domestic and industrial wastes, thus being major pathways for dissolved and particle-bound pollutant transfer into perennial streams and rivers. All the problems listed require detailed hydrological and geomorphic investigations in order to provide sound basis for developing appropriate measures aimed to control and decrease urban erosion, sediment redistribution, pollution of water bodies, damage to constructions and communications. Recent advances in sediment tracing and fingerprinting techniques provide promising opportunities

  12. Naphthalene biodegradation in temperate and arctic marine microcosms.

    Science.gov (United States)

    Bagi, Andrea; Pampanin, Daniela M; Lanzén, Anders; Bilstad, Torleiv; Kommedal, Roald

    2014-02-01

    Naphthalene, the smallest polycyclic aromatic hydrocarbon (PAH), is found in abundance in crude oil, its major source in marine environments. PAH removal occurs via biodegradation, a key process determining their fate in the sea. Adequate estimation of PAH biodegradation rates is essential for environmental risk assessment and response planning using numerical models such as the oil spill contingency and response (OSCAR) model. Using naphthalene as a model compound, biodegradation rate, temperature response and bacterial community composition of seawaters from two climatically different areas (North Sea and Arctic Ocean) were studied and compared. Naphthalene degradation was followed by measuring oxygen consumption in closed bottles using the OxiTop(®) system. Microbial communities of untreated and naphthalene exposed samples were analysed by polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) and pyrosequencing. Three times higher naphthalene degradation rate coefficients were observed in arctic seawater samples compared to temperate, at all incubation temperatures. Rate coefficients at in situ temperatures were however, similar (0.048 day(-1) for temperate and 0.068 day(-1) for arctic). Naphthalene biodegradation rates decreased with similar Q10 ratios (3.3 and 3.5) in both seawaters. Using the temperature compensation method implemented in the OSCAR model, Q10 = 2, biodegradation in arctic seawater was underestimated when calculated from the measured temperate k1 value, showing that temperature difference alone could not predict biodegradation rates adequately. Temperate and arctic untreated seawater communities were different as revealed by pyrosequencing. Geographic origin of seawater affected the community composition of exposed samples.

  13. Association of heart rate variability and inflammatory response in patients with cardiovascular diseases: current strengths and limitations.

    Science.gov (United States)

    Papaioannou, Vasilios; Pneumatikos, Ioannis; Maglaveras, Nikos

    2013-01-01

    Many experimental and clinical studies have confirmed a continuous cross-talk between both sympathetic and parasympathetic branches of autonomic nervous system and inflammatory response, in different clinical scenarios. In cardiovascular diseases, inflammation has been proven to play a pivotal role in disease progression, pathogenesis and resolution. A few clinical studies have assessed the possible inter-relation between neuro-autonomic output, estimated with heart rate variability analysis, which is the variability of R-R in the electrocardiogram, and different inflammatory biomarkers, in patients suffering from stable or unstable coronary artery disease (CAD) and heart failure. Moreover, different indices derived from heart rate signals' processing, have been proven to correlate strongly with severity of heart disease and predict final outcome. In this review article we will summarize major findings from different investigators, evaluating neuro-immunological interactions through heart rate variability analysis, in different groups of cardiovascular patients. We suggest that markers originating from variability analysis of heart rate signals seem to be related to inflammatory biomarkers. However, a lot of open questions remain to be addressed, regarding the existence of a true association between heart rate variability and autonomic nervous system output or its adoption for risk stratification and therapeutic monitoring at the bedside. Finally, potential therapeutic implications will be discussed, leading to autonomic balance restoration in relation with inflammatory control.

  14. Spatial and temporal variability in response to hybrid electro-optical stimulation

    Science.gov (United States)

    Duke, Austin R.; Lu, Hui; Jenkins, Michael W.; Chiel, Hillel J.; Jansen, E. Duco

    2012-06-01

    Hybrid electro-optical neural stimulation is a novel paradigm combining the advantages of optical and electrical stimulation techniques while reducing their respective limitations. However, in order to fulfill its promise, this technique requires reduced variability and improved reproducibility. Here we used a comparative physiological approach to aid the further development of this technique by identifying the spatial and temporal factors characteristic of hybrid stimulation that may contribute to experimental variability and/or a lack of reproducibility. Using transient pulses of infrared light delivered simultaneously with a bipolar electrical stimulus in either the marine mollusk Aplysia californica buccal nerve or the rat sciatic nerve, we determined the existence of a finite region of excitability with size altered by the strength of the optical stimulus and recruitment dictated by the polarity of the electrical stimulus. Hybrid stimulation radiant exposures yielding 50% probability of firing (RE50) were shown to be negatively correlated with the underlying changes in electrical stimulation threshold over time. In Aplysia, but not in the rat sciatic nerve, increasing optical radiant exposures (J cm-2) beyond the RE50 ultimately resulted in inhibition of evoked potentials. Accounting for the sources of variability identified in this study increased the reproducibility of stimulation from 35% to 93% in Aplysia and 23% to 76% in the rat with reduced variability.

  15. Cortical Response Variability as a Developmental Index of Selective Auditory Attention

    Science.gov (United States)

    Strait, Dana L.; Slater, Jessica; Abecassis, Victor; Kraus, Nina

    2014-01-01

    Attention induces synchronicity in neuronal firing for the encoding of a given stimulus at the exclusion of others. Recently, we reported decreased variability in scalp-recorded cortical evoked potentials to attended compared with ignored speech in adults. Here we aimed to determine the developmental time course for this neural index of auditory…

  16. Financial liberalisation and political variables: A response to Abiad and Mody

    NARCIS (Netherlands)

    Burgoon, B.; Demetriades, P.; Underhill, G.

    2008-01-01

    We challenge recent findings by Abiad and Mody (2005) which suggest that financial liberalization has little to do with political variables. This analysis is at odds with some of the established literature, and only with difficulty comes to terms with the considerable cross-national variation in the

  17. Whole plant phenotypic variability in nitrogen and phosphorus response of Brachypodium distachyon

    Science.gov (United States)

    This work evaluates the phenotypic response of the model grass (Brachypodium distachyon) to nitrogen and phosphorus nutrition. Reference line Bd21-3 was grown in sand under controlled conditions using 11 phosphorus and 11 nitrogen application rates. We established a dose-response curve for both nit...

  18. A Latent Variables Examination of Processing Speed, Response Inhibition, and Working Memory during Typical Development

    Science.gov (United States)

    McAuley, Tara; White, Desiree A.

    2011-01-01

    This study addressed three related aims: (a) to replicate and extend previous work regarding the nonunitary nature of processing speed, response inhibition, and working memory during development; (b) to quantify the rate at which processing speed, response inhibition, and working memory develop and the extent to which the development of these…

  19. Biodegradation of polyethoxylated nonylphenols.

    Science.gov (United States)

    Ruiz, Yassellis; Medina, Luis; Borusiak, Margarita; Ramos, Nairalith; Pinto, Gilberto; Valbuena, Oscar

    2013-01-01

    Polyethoxylated nonylphenols, with different ethoxylation degrees (NPEO x ), are incorporated into many commercial and industrial products such as detergents, domestic disinfectants, emulsifiers, cosmetics, and pesticides. However, the toxic effects exerted by their degradation products, which are persistent in natural environments, have been demonstrated in several animal and invertebrate aquatic species. Therefore, it seems appropriate to look for indigenous bacteria capable of degrading native NPEO x and its derivatives. In this paper, the isolation of five bacterial strains, capable of using NPEO 15 , as unique carbon source, is described. The most efficient NPEO 15 degrader bacterial strains were identified as Pseudomonas fluorescens (strain Yas2) and Klebsiella pneumoniae (strain Yas1). Maximal growth rates were reached at pH 8, 27°C in a 5% NPEO 15 medium. The NPEO 15 degradation extension, followed by viscometry assays, reached 65% after 54.5 h and 134 h incubation times, while the COD values decreased by 95% and 85% after 24 h for the Yas1 and Yas2 systems, respectively. The BOD was reduced by 99% and 99.9% levels in 24 h and 48 h incubations. The viscosity data indicated that the NPEO 15 biodegradation by Yas2 follows first-order kinetics. Kinetic rate constant (k) and half life time (τ) for this biotransformation were estimated to be 0.0072 h(-1) and 96.3 h, respectively.

  20. Biodegradable and radically polymerized elastomers with enhanced processing capabilities.

    Science.gov (United States)

    Ifkovits, Jamie L; Padera, Robert F; Burdick, Jason A

    2008-09-01

    The development of biodegradable materials with elastomeric properties is beneficial for a variety of applications, including for use in the engineering of soft tissues. Although others have developed biodegradable elastomers, they are restricted by their processing at high temperatures and under vacuum, which limits their fabrication into complex scaffolds. To overcome this, we have modified precursors to a tough biodegradable elastomer, poly(glycerol sebacate) (PGS) with acrylates to impart control over the crosslinking process and allow for more processing options. The acrylated-PGS (Acr-PGS) macromers are capable of crosslinking through free radical initiation mechanisms (e.g., redox and photo-initiated polymerizations). Alterations in the molecular weight and % acrylation of the Acr-PGS led to changes in formed network mechanical properties. In general, Young's modulus increased with % acrylation and the % strain at break increased with molecular weight when the % acrylation was held constant. Based on the mechanical properties, one macromer was further investigated for in vitro and in vivo degradation and biocompatibility. A mild to moderate inflammatory response typical of implantable biodegradable polymers was observed, even when formed as an injectable system with redox initiation. Moreover, fibrous scaffolds of Acr-PGS and a carrier polymer, poly(ethylene oxide), were prepared via an electrospinning and photopolymerization technique and the fiber morphology was dependent on the ratio of these components. This system provides biodegradable polymers with tunable properties and enhanced processing capabilities towards the advancement of approaches in engineering soft tissues.

  1. Dose-Response Modeling Under Simple Order Restrictions Using Bayesian Variable Selection Methods

    OpenAIRE

    Otava, Martin; Shkedy, Ziv; Lin, Dan; Goehlmann, Hinrich W. H.; Bijnens, Luc; Talloen, Willem; Kasim, Adetayo

    2014-01-01

    Bayesian modeling of dose–response data offers the possibility to establish the relationship between a clinical or a genomic response and increasing doses of a therapeutic compound and to determine the nature of the relationship wherever it exists. In this article, we focus on an order-restricted one-way ANOVA model which can be used to test the null hypothesis of no dose effect against an ordered alternative. Within the framework of the dose–response modeling, a model uncertainty can be addr...

  2. Investigation of the prefrontal cortex in response to duration-variable anagram tasks using functional near infrared spectroscopy

    Science.gov (United States)

    Tian, Fenghua; Chance, Britton; Liu, Hanli

    2009-02-01

    The Prefrontal Cortex (PFC) in response to anagram tasks was investigated using multi-channel, functional Near Infrared Spectroscopy (fNIRS). The study focused on the variability of PFC response with variable anagram durations (executing time). The duration of the anagram ranged from a few seconds to over one minute. The topographic image of PFC showed high lateral consistency across different anagram durations and did not show remarkable discrimination between two difficulty levels: 4-letter and 6-letter anagrams. The superposition principle of a linear system model was employed to investigate the possible non-linearity between three discrete duration subgroups (D1 = 2 +/- 0.33, D2 = 4 +/- 0.67, and D3 = 8 +/- 1.00 sec) and their resultant fNIR readings. Such analysis showed clearly a nonlinear behavior in fNIRS signals within the duration range of less than 4 sec, agreeing with the previous studies on cognitive response measured with functional Magnetic Resonant Imaging (fMRI). To our knowledge, this is the first report on the nonlinearity of cognitive response using fNIRS.

  3. Comparative response of Rangifer tarandus and other northern ungulates to climatic variability

    Directory of Open Access Journals (Sweden)

    Robert B. Weladji

    2002-06-01

    Full Text Available To understand the factors influencing life history traits and population dynamics, attention is increasingly being given to the importance of environmental stochasticity. In this paper, we review and discuss aspects of current knowledge concerning the effect of climatic variation (local and global on population parameters of northern ungu¬lates, with special emphasis on reindeer/caribou (Rangifer tarandus. We also restrict ourselves to indirect effects of climate through both forage availability and quality, and insect activity. Various authors have used different weather variables; with sometime opposite trends in resulting life history traits of ungulates, and few studies show consistent effects to the same climatic variables. There is thus little consensus about which weather variables play the most sig¬nificant role influencing ungulate population parameters. This may be because the effects of weather on ungulate pop¬ulation dynamics and life history traits are scale dependent and it is difficult to isolate climatic effects from density dependent factors. This confirms the complexity of the relationship between environment and ecosystem. We point out limits of comparability between systems and the difficulty of generalizing about the effect of climate change broadly across northern systems, across species and even within species. Furthermore, insect harassment appears to be a key climate-related factor for the ecology of reindeer/caribou that has been overlooked in the literature of climatic effects on large herbivores. In light of this, there is a need for further studies of long time series in assessing effects of climate variability on reindeer/caribou.

  4. Variability of growing degree days in Poland in response to ongoing climate changes in Europe

    Science.gov (United States)

    Wypych, Agnieszka; Sulikowska, Agnieszka; Ustrnul, Zbigniew; Czekierda, Danuta

    2017-01-01

    An observed increase in air temperature can lead to significant changes in the phenology of plants and, consequently, changes in agricultural production. The aim of the study was to evaluate the spatial differentiation of thermal resources in Poland and their variability during a period of changing thermal conditions in Europe. Since the variability of thermal conditions is of paramount importance for perennial crops, the study focused on apple, plum, and cherry orchard regions in Poland. The analysis was conducted for the period of 1951-2010 using air temperature daily data. Thermal resources have been defined using the growing degree days (GDD) index calculated independently for the whole year and during in frost-free season for three air temperature thresholds: 0, 5, and 10 °C, which determine the non-winter period, growing season, and the period of full plant growth, respectively. In addition, due to the high significance for perennials in particular, the incidence and intensity of frost during flowering were calculated. In this study, a detailed analysis of the spatial differentiation of thermal resources was first performed, followed by an evaluation of long-term variability and associated change patterns. The obtained results confirmed an increase in thermal resources in Poland as a consequence of the lengthening of the growing season. However, the frequency and intensity of spring frost, especially during flowering or even during ripening of plants, remain a threat to harvests in both the eastern and western parts of the country.

  5. Complex Response of White Pines to Past Environmental Variability Increases Understanding of Future Vulnerability

    OpenAIRE

    2015-01-01

    Ecological niche models predict plant responses to climate change by circumscribing species distributions within a multivariate environmental framework. Most projections based on modern bioclimatic correlations imply that high-elevation species are likely to be extirpated from their current ranges as a result of rising growing-season temperatures in the coming decades. Paleoecological data spanning the last 15,000 years from the Greater Yellowstone region describe the response of vegetation t...

  6. Separation of multiple evoked responses using differential amplitude and latency variability

    OpenAIRE

    Kevin H. Knuth; Truccolo, Wilson A.; Bressler, Steven L.; Ding, Mingzhou

    2002-01-01

    In neuroelectrophysiology one records electric potentials or magnetic fields generated by ensembles of synchronously active neurons in response to externally presented stimuli. These evoked responses are often produced by multiple generators in the presence of ongoing background activity. While source localization techniques or current source density estimation are usually used to identify generators, application of blind source separation techniques to obtain independent components has becom...

  7. Idiotypes as immunogens: facing the challenge of inducing strong therapeutic immune responses against the variable region of immunoglobulins.

    Directory of Open Access Journals (Sweden)

    Alejandro eLopez-Requena

    2012-11-01

    Full Text Available Idiotype (Id-based immunotherapy has been exploited as cancer treatment option. Conceived as therapy for malignancies bearing idiotypic antigens, it has been also extended to solid tumours because of the capacity of anti-idiotypic antibodies to mimick Id-unrelated antigens. In both these two settings, efforts are being made to overcome the poor immune responsiveness often experienced when using self immunoglobulins as immunogens. Despite bearing a unique gene combination, and thus particular epitopes, it is normally difficult to stimulate the immune response against antibody variable regions. Different strategies are currently used to strengthen Id immunogenicity, such as concomitant use of immune-stimulating molecules, design of Id-containing immunogenic recombinant proteins, specific targeting of relevant immune cells and genetic immunization. This review focuses on the role of anti-Id vaccination in cancer management and on the current developments used to foster anti-idiotypic B- and T-cell responses.

  8. Stroke volume variation and pleth variability index to predict fluid responsiveness during resection of primary retroperitoneal tumors in Hans Chinese.

    Science.gov (United States)

    Fu, Q; Mi, W D; Zhang, H

    2012-02-01

    Respiration variation in arterial pulse pressure (ΔPP) and pulse oximetry plethysmographic waveform amplitude (ΔPOP) are accurate predictors of fluid responsiveness in mechanically ventilated patients. We hypothesized that stroke volume variation (SVV) and pleth variability index (PVI) can predict fluid responsiveness in mechanically ventilated patients during major surgical procedures in Hans Chinese. This prospective study consisted of fifty-five Hans Chinese patients undergoing resection of primary retroperitoneal tumors (PRPT). During the surgical procedures, hemodynamic data [central venous pressure (CVP), cardiac index (CI), stroke volume index (SVI), SVV, and PVI] were recorded before and after volume expansion (VE) (8 ml•kg-1 of 6% hydroxyethyl starch 130/0.4). Fluid responsiveness was defined as an increase in SVI ≥ 10% after VE. Four patients were excluded from analysis for arrhythmia or obvious hemorrhage during VE. Baseline SVV correlated well with baseline PVI and the changes in SVV was correlated with the changes in PVI (p Chinese.

  9. Characterization of a Novel Butachlor Biodegradation Pathway and Cloning of the Debutoxylase (Dbo) Gene Responsible for Debutoxylation of Butachlor in Bacillus sp. hys-1.

    Science.gov (United States)

    Gao, Yang; Jin, Lei; Shi, Hui; Chu, Zhangjie

    2015-09-30

    Bacillus sp. strain hys-1, which was isolated from active sludge, could degrade >90% butachlor at a concentration of 100 mg/L within 7 days. The present work revealed that strain hys-1 could mineralize butachlor via the following pathway: butachlor was initially metabolized to 2-chloro-N-(2,6-diethylphenyl)-N-methylacetamide by debutoxylation and then transformed to form 2-chloro-N-(2,6-diethylphenyl)acetamide by N-demethylation. Subsequently, it was converted to 2,6-diethylaniline and further mineralized into CO2 and H2O. In addition, the catalytic efficiency of crude cell extracts descended as follows: alachlor > acetochlor > butachlor. Furthermore, a novel 744 bp gene responsible for transforming butachlor into 2-chloro-N-(2,6-diethylphenyl)-N-methylacetamide was cloned from strain hys-1 and the encoding debutoxylase was designated Dbo. Then Dbo was expressed in Escherichia coli BL21 (DE3) and purified using Ni-nitrilotriacetic acid affinity chromatography. Dbo displayed the highest activity against butachlor at pH 6.5 and 30 °C. Metal ions played an important role in Dbo activity. To the best of the authors' knowledge, this is the first report that strain hys-1 can mineralize butachlor by a novel metabolic mechanism and the first identification of a gene encoding butachlor debutoxylase.

  10. Acetylcholine-Based Entropy in Response Selection: A Model of How Striatal Interneurons Modulate Exploration, Exploitation, and Response Variability in Decision Making

    Directory of Open Access Journals (Sweden)

    Andrea eStocco

    2012-02-01

    Full Text Available The basal ganglia play a fundamental role in decision making. Their contribution is typically modeled within a reinforcement learning framework, with the basal ganglia learning to select the options associated with highest value and their dopamine inputs conveying performance feedback. This basic framework, however, does not account for the role of cholinergic interneurons in the striatum, and does not easily explain certain dynamic aspects of decision-making and skill acquisition like the generation of exploratory actions. This paper describes BABE (Basal ganglia Acetylcholine-Based Entropy, a model of the acetylcholine system in the striatum that provides a unified explanation for these phenomena. According to this model, cholinergic interneurons in the striatum control the level of variability in behavior by modulating the number of possible responses that are considered by the basal ganglia, as well as the level of competition between them. This mechanism provides a natural way to account for the role of basal ganglia in generating behavioral variability during the acquisition of certain cognitive skills, as well as for modulating exploration and exploitation in decision making. Compared to a typical reinforcement learning model, BABE showed a greater modulation of response variability in the face of changes in the reward contingencies, allowing for faster learning (and re-learning of option values. Finally, the paper discusses the possible applications of the model to other domains.

  11. Adhesion of biocompatible and biodegradable micropatterned surfaces

    NARCIS (Netherlands)

    Kaiser, J.S.; Kamperman, M.M.G.; Souza, E.J.; Schick, B.; Arzt, E.

    2011-01-01

    We studied the effects of pillar dimensions and stiffness of biocompatible and biodegradable micropatterned surfaces on adhesion on different compliant substrates. The micropatterned adhesives were based on biocompatible polydimethylsiloxane (PDMS) and biodegradable poly(lactic-co-glycolic) acid (PL

  12. HDL-C Response Variability to Niacin ER in US Adults

    Directory of Open Access Journals (Sweden)

    Jennifer B. Christian

    2013-01-01

    Full Text Available Background. Niacin is the most effective treatment currently available for raising HDL-C levels. Objective. To evaluate if gender and baseline lipid levels have an effect on the HDL-C response of niacin ER and to identify factors that predict response to niacin ER at the 500 mg dose. Material and Methods. The change in HDL-C effect between baseline and follow-up levels was quantified in absolute change as well as dichotomized into high versus low response (high response was defined as an HDL-C effect of >15% increase and low response was HDL-C <5% in a sample of 834 individuals. Results. Both males and females with low HDL-C levels at baseline exhibited a response to treatment in the multivariate model (males, HDL-C <40 mg/dL: OR=5.18, 95% CI: 2.36–11.39; females, HDL-C <50 mg/dL: OR=5.40, 95% CI: 1.84–15.79. There was also a significant difference in the mean HDL-C effect between baseline and follow-up HDL-C levels in the 500 mg niacin ER dose group for both males (mean HDL-C effect = 0.08, P<0.001 and females (mean HDL-C effect = 0.10, P=0.019. Conclusion. Baseline HDL-C levels are the biggest predictor of response to niacin ER treatment for both males and females among the factors evaluated.

  13. Coherence among the Northern Hemisphere land, cryosphere, and ocean responses to natural variability and anthropogenic forcing during the satellite era

    Science.gov (United States)

    Gonsamo, Alemu; Chen, Jing M.; Shindell, Drew T.; Asner, Gregory P.

    2016-08-01

    A lack of long-term measurements across Earth's biological and physical systems has made observation-based detection and attribution of climate change impacts to anthropogenic forcing and natural variability difficult. Here we explore coherence among land, cryosphere and ocean responses to recent climate change using 3 decades (1980-2012) of observational satellite and field data throughout the Northern Hemisphere. Our results show coherent interannual variability among snow cover, spring phenology, solar radiation, Scandinavian Pattern, and North Atlantic Oscillation. The interannual variability of the atmospheric peak-to-trough CO2 amplitude is mostly impacted by temperature-mediated effects of El Niño/Southern Oscillation (ENSO) and Pacific/North American Pattern (PNA), whereas CO2 concentration is affected by Polar Pattern control on sea ice extent dynamics. This is assuming the trend in anthropogenic CO2 emission remains constant, or the interannual changes in the trends are negligible. Our analysis suggests that sea ice decline-related CO2 release may outweigh increased CO2 uptake through longer growing seasons and higher temperatures. The direct effects of variation in solar radiation and leading teleconnections, at least in part via their impacts on temperature, dominate the interannual variability of land, cryosphere and ocean indicators. Our results reveal a coherent long-term changes in multiple physical and biological systems that are consistent with anthropogenic forcing of Earth's climate and inconsistent with natural drivers.

  14. Variable epitope libraries: new vaccine immunogens capable of inducing broad human immunodeficiency virus type 1-neutralizing antibody response.

    Science.gov (United States)

    Charles-Niño, Claudia; Pedroza-Roldan, Cesar; Viveros, Monica; Gevorkian, Goar; Manoutcharian, Karen

    2011-07-18

    The extreme antigenic variability of human immunodeficiency virus (HIV) leads to immune escape of the virus, representing a major challenge in the design of effective vaccine. We have developed a novel concept for immunogen construction based on introduction of massive mutations within the epitopes targeting antigenically variable pathogens and diseases. Previously, we showed that these immunogens carrying large combinatorial libraries of mutated epitope variants, termed as variable epitope libraries (VELs), induce potent, broad and long lasting CD8+IFN-γ+ T-cell response. Moreover, we demonstrated that these T cells recognize more than 50% of heavily mutated variants (5 out of 10 amino acid positions were mutated in each epitope variant) of HIV-1 gp120 V3 loop-derived cytotoxic T lymphocyte epitope (RGPGRAFVTI) in mice. The constructed VELs had complexities of 10000 and 12500 individual members, generated as plasmid DNA or as M13 phage display combinatorial libraries, respectively, and with structural composition RGPGXAXXXX or XGXGXAXVXI, where X is any of 20 natural amino acids. Here, we demonstrated that sera from mice immunized with these VELs are capable of neutralizing 5 out of 10 viral isolates from Tier 2 reference panel of subtype B envelope clones, including HIV-1 isolates which are known to be resistant to neutralization by several potent monoclonal antibodies, described previously. These data indicate the feasibility of the application of immunogens based on VEL concept as an alternative approach for the development of molecular vaccines against antigenically variable pathogens.

  15. Persistent thermal fronts in the Black Sea: Existence, variability, and response to atmospheric forcing

    Science.gov (United States)

    Kazmin, A. S.

    2016-05-01

    High-resolution satellite sea surface temperature (SST) measurements (PATHFINDER dataset) have been used to confirm an existence of persistent thermal frontal zones in the Black Sea. Fronts have been revealed in the winter season between the intensively cooling shallow northwestern area and warmer waters of central part, and in spring-summer season between the actively warming waters of the southeastern part and cooler central area. Interannual and quasi-decadal variability of the northwestern front have been documented, as well as a high negative correlation of its intensity with the winter-mean SST.

  16. Biodegradation Rates Assessment For An In Situ Bioremediation Process

    Science.gov (United States)

    Troquet, J.; Poutier, F.

    Bioremediation methods seem a promising way of dealing with soil and subsoil con- tamination by organic substances. The biodegradation process is supported by micro- organisms which use the organic carbon from the pollutants as energy source and cells building blocks. However, bioremediation is not yet universally understood and its success is still an intensively debated issue because all soils and groundwater are not able to sustain biological growth and, then, cannot be successfully bioremediated. The outcome of each degradation process depends on several factors, which, such as oxygen transfer and pollutant bio-availability, can be controlled and are therefore key variables of such bioremediation processes. Then, it is essential to carry out a fea- sibility study based on pilot-testing before starting a remediation project in order to determine the best formulation of nutrients and bacteria to use for the specific condi- tions encountered. The scope of this work is to study the main parameters of the process and its physi- cal limiting steps in order to determine the biodegradation rates in a specific case of contamination. Several ground samples from an actual petroleum hydrocarbon con- taminated site have been laboratory tested. Five fixed bed column reactors, enabling the study of the influence of the different op- erating variables on the biodegradation kinetics, are used. The stoichiometric equation for bacteria growth and pollutant degradation has been established, allowing the de- termination of mass balances. Biodegradation monitoring is achieved by continuously measuring the emissions of carbon dioxide production and intermittently by analysing residual hydrocarbons. Results lead to the knowledge of biodegradation rates which allow to determine the treatment duration and cost.

  17. Precipitation variability and response to changing climatic condition in the Yarlung Tsangpo River basin, China

    Science.gov (United States)

    Sang, Yan-Fang; Singh, Vijay P.; Gong, Tongliang; Xu, Kang; Sun, Fubao; Liu, Changming; Liu, Wenbin; Chen, Ruizhi

    2016-08-01

    Hydroclimatic process in the Yarlung Tsangpo River (YTR) basin, a sensitive area to climate change, is obviously changing during recent years, but there has limited understanding about it. In this study, we investigated the spatiotemporal variation of precipitation over last four decades in the basin and the impact thereon of the changing Indian summer monsoon at interannual and decadal time scales. All the precipitation series have similar scaling behavior, reflecting similar climatic regime throughout the basin. However, the effect of the Indian monsoon strengthens from the downstream to upstream, causing spatial variability in the seasonal distribution of precipitation, and on this basis, the YTR basin is roughly divided into three regions: east, middle, and west. Both the occurrence times and magnitude of precipitation extremes, ranging 25-50 mm/d, are exhibiting downward trends over the last four decades, which bodes well for water disaster controls in the basin. The Indian summer monsoon index, as an intensity indicator for the Indian summer monsoon, shows a positive relationship with the summer precipitation in the YTR basin. Periodic variability of the Indian monsoon determines the interannual nonstationary fluctuations of precipitation. Especially, the weakening effect of the Indian summer monsoon has caused an obvious decrease in precipitation over the rainy season after 1998. If the Indian summer monsoon keeps weakening, the precipitation would decrease and potentially water shortage would become more severe in the basin. Effective adaptation strategy should therefore be developed proactively to handle the unfavorable water situation, which is likely to occur in the future.

  18. Auditory stimulation with music influences the geometric indices of heart rate variability in response to the postural change maneuver

    Directory of Open Access Journals (Sweden)

    Bianca C. R. de Castro

    2014-01-01

    Full Text Available It is poor in the literature the behavior of the geometric indices of heart rate variability (HRV during the musical auditory stimulation. The objective is to investigate the acute effects of classic musical auditory stimulation on the geometric indexes of HRV in women in response to the postural change maneuver (PCM. We evaluated 11 healthy women between 18 and 25 years old. We analyzed the following indices: Triangular index, Triangular interpolation of RR intervals and Poincarι plot (standard deviation of the instantaneous variability of the beat-to beat heart rate [SD1], standard deviation of long-term continuous RR interval variability and Ratio between the short - and long-term variations of RR intervals [SD1/SD2] ratio. HRV was recorded at seated rest for 10 min. The women quickly stood up from a seated position in up to 3 s and remained standing still for 15 min. HRV was recorded at the following periods: Rest, 0-5 min, 5-10 min and 10-15 min during standing. In the second protocol, the subject was exposed to auditory musical stimulation (Pachelbel-Canon in D for 10 min at seated position before standing position. Shapiro-Wilk to verify normality of data and ANOVA for repeated measures followed by the Bonferroni test for parametric variables and Friedman′s followed by the Dunn′s posttest for non-parametric distributions. In the first protocol, all indices were reduced at 10-15 min after the volunteers stood up. In the protocol musical auditory stimulation, the SD1 index was reduced at 5-10 min after the volunteers stood up compared with the music period. The SD1/SD2 ratio was decreased at control and music period compared with 5-10 min after the volunteers stood up. Musical auditory stimulation attenuates the cardiac autonomic responses to the PCM.

  19. Development of aliphatic biodegradable photoluminescent polymers

    Science.gov (United States)

    Yang, Jian; Zhang, Yi; Gautam, Santosh; Liu, Li; Dey, Jagannath; Chen, Wei; Mason, Ralph P.; Serrano, Carlos A.; Schug, Kevin A.; Tang, Liping

    2009-01-01

    None of the current biodegradable polymers can function as both implant materials and fluorescent imaging probes. The objective of this study was to develop aliphatic biodegradable photoluminescent polymers (BPLPs) and their associated cross-linked variants (CBPLPs) for biomedical applications. BPLPs are degradable oligomers synthesized from biocompatible monomers including citric acid, aliphatic diols, and various amino acids via a convenient and cost-effective polycondensation reaction. BPLPs can be further cross-linked into elastomeric cross-linked polymers, CBPLPs. We have shown representatively that BPLP-cysteine (BPLP-Cys) and BPLP-serine (BPLP-Ser) offer advantages over the traditional fluorescent organic dyes and quantum dots because of their preliminarily demonstrated cytocompatibility in vitro, minimal chronic inflammatory responses in vivo, controlled degradability and high quantum yields (up to 62.33%), tunable fluorescence emission (up to 725 nm), and photostability. The tensile strength of CBPLP-Cys film ranged from 3.25 ± 0.13 MPa to 6.5 ± 0.8 MPa and the initial Modulus was in a range of 3.34 ± 0.15 MPa to 7.02 ± 1.40 MPa. Elastic CBPLP-Cys could be elongated up to 240 ± 36%. The compressive modulus of BPLP-Cys (0.6) (1:1:0.6 OD:CA:Cys) porous scaffold was 39.60 ± 5.90 KPa confirming the soft nature of the scaffolds. BPLPs also possess great processability for micro/nano-fabrication. We demonstrate the feasibility of using BPLP-Ser nanoparticles (“biodegradable quantum dots”) for in vitro cellular labeling and noninvasive in vivo imaging of tissue engineering scaffolds. The development of BPLPs and CBPLPs represents a new direction in developing fluorescent biomaterials and could impact tissue engineering, drug delivery, bioimaging. PMID:19506254

  20. The Effects of Audience Interest, Responsiveness, and Evaluation on Public Speaking Anxiety and Related Variables.

    Science.gov (United States)

    MacIntyre, Peter D.; Thivierge, Kimly A.; MacDonald, J. Renee

    1997-01-01

    Examines potential sources of public-speaking anxiety among undergraduate students stemming from the audience. Identifies three sources of anxiety: degree of formal evaluation, level of audience interest in the topic, and audience's responsiveness to the speaker. Measures willingness to speak and expected speech quality. Finds interest,…

  1. ACE genetic variability and response to fluoxetine: lack of association in depressed patients

    Directory of Open Access Journals (Sweden)

    Negar Firouzabadi

    2015-12-01

    Full Text Available Evidences suggest that besides the neurotransmitters contributing to the development of depression, renin-angiotensin system (RAS may also have a substantial role. Certain polymorphisms of RAS are associated with over activity of RAS & depression. Considering that antidepressants reduce the actions of angiotensin II, the main product of RAS, this may come into mind that genetic polymorphisms of the mentioned system may affect the outcome of therapy in depressed patients. In the present study, 100 newly diagnosed depressed patients, according to DSM-IV criteria, were treated with 20 mg of fluoxetine or 8-12 weeks. Patients were categorized into responsive and non-responsive groups according to 50% reduction in symptoms. Genotype frequencies of angiotensin-converting enzyme (ACE gene [ACE (I/D, A-240T and A2350G] were then determined in DNAs extracted from venous blood of the patients using polymerase chain reaction–restriction fragment length polymorphism (PCR– RFLP and PCR. Results indicate that polymorphisms studied and their haplotypes were not associated with better response to fluoxetine. However, a strong association between age and treatment in depressed Iranian patients was observed (P=0.001. In conclusion, unlike previous reports, this study does not support the hypothesis of special genotypes of RAS contributing to a better response to antidepressants in depressed patients.

  2. Utility of Extinction-Induced Response Variability for the Selection of Mands

    Science.gov (United States)

    Grow, Laura L.; Kelley, Michael E.; Roane, Henry S.; Shillingsburg, M. Alice

    2008-01-01

    Functional communication training (FCT; Carr & Durand, 1985) is a commonly used differential reinforcement procedure for replacing problem behavior with socially acceptable alternative responses. Most studies in the FCT literature consist of demonstrations of the maintenance of responding when various treatment components (e.g., extinction,…

  3. Energetic plasticity underlies a variable response to ocean acidification in the pteropod, Limacina helicina antarctica.

    Directory of Open Access Journals (Sweden)

    Brad A Seibel

    Full Text Available Ocean acidification, caused by elevated seawater carbon dioxide levels, may have a deleterious impact on energetic processes in animals. Here we show that high PCO(2 can suppress metabolism, measured as oxygen consumption, in the pteropod, L. helicina forma antarctica, by ∼20%. The rates measured at 180-380 µatm (MO(2  =  1.25 M(-0.25, p  =  0.007 were significantly higher (ANCOVA, p  =  0.004 than those measured at elevated target CO(2 levels in 2007 (789-1000 µatm,  =  0.78 M(-0.32, p  =  0.0008; Fig. 1. However, we further demonstrate metabolic plasticity in response to regional phytoplankton concentration and that the response to CO(2 is dependent on the baseline level of metabolism. We hypothesize that reduced regional Chl a levels in 2008 suppressed metabolism and masked the effect of ocean acidification. This effect of food limitation was not, we postulate, merely a result of gut clearance and specific dynamic action, but rather represents a sustained metabolic response to regional conditions. Thus, pteropod populations may be compromised by climate change, both directly via CO(2-induced metabolic suppression, and indirectly via quantitative and qualitative changes to the phytoplankton community. Without the context provided by long-term observations (four seasons and a multi-faceted laboratory analysis of the parameters affecting energetics, the complex response of polar pteropods to ocean acidification may be masked or misinterpreted.

  4. Production of mono- and di-carboxylated polyethylene glycols as a factor obstacle to the successful ozonation-assisted biodegradation of ethoxylated compounds.

    Science.gov (United States)

    Nakai, Satoshi; Okuda, Tetsuji; Nishijima, Wataru; Okada, Mitsumasa

    2015-10-01

    Ozonation is believed to improve the biodegradability of organic compounds. In the present study, degradation of nonylphenol ethoxylates (NPEOs) was monitored in hybrid treatment systems consisting of ozonation and microbial degradation processes. We found that ozonation of NPEOs decreased, rather than increased, the biodegradability under certain conditions. The timing of ozonation was a definitive factor in determining whether ozonation increased or decreased the biodegradation rates of NPEOs. Initial ozonation of NPEOs prior to biodegradation reduced the rate of dissolved organic carbon (DOC) removal during the subsequent 14 d of biodegradation, whereas intermediate ozonation at the 9th day of biodegradation improved subsequent DOC removal during 14 d of NPEO biodegradation. Furthermore, reduction of DOC removal was also observed, when initial ozonation prior to biodegradation was subjected to cetyl alcohol ethoxylates. The production of less biodegradable intermediates, such as mono- and dicarboxylated polyethylene glycols (MCPEGs and DCPEGs), was responsible for the negative effect of ozonation on biodegradability of NPEOs. DCPEGs and MCPEGs were produced by biodegradation of polyethylene glycols (PEGs) that were ozonolysis products of the NPEOs, and the biodegradability of DCPEGs and MCPEGs was less than that of the precursor PEGs. The results indicate that, if the target chemicals contain ethoxy chains, production of PEGs may be one of the important factors when ozonation is considered.

  5. Response of birds to climatic variability; evidence from the western fringe of Europe

    Science.gov (United States)

    Donnelly, Alison; Cooney, Tom; Jennings, Eleanor; Buscardo, Erika; Jones, Mike

    2009-05-01

    Ireland’s geographic location on the western fringe of the European continent, together with its island status and impoverished avifauna, provides a unique opportunity to observe changes in bird migration and distribution patterns in response to changing climatic conditions. Spring temperatures have increased in western Europe over the past 30 years in line with reported global warming. These have been shown, at least in part, to be responsible for changes in the timing of life cycle events (phenology) of plants and animals. In order to investigate the response of bird species in Ireland to changes in temperature, we examined ornithological records of trans-Saharan migrants over the 31-year period 1969-1999. Analysis of the data revealed that two discrete climatic phenomena produced different responses in summer migrant bird species. Firstly, a number of long-distance migrants showed a significant trend towards earlier arrival. This trend was evident in some species and was found to be a response to increasing spring air temperature particularly in the month of March. Secondly, (1) a step change in the pattern of occurrences of non-breeding migrant bird species, and (2) an increase in the ringing data of migrant species were found to correlate with a step change in temperature in 1987-1988. These results indicate that, for migrant bird species, the impact of a sudden change in temperature can be as important as any long-term monotonic trend, and we suggest that the impact of step change events merits further investigation on a wider range of species and across a greater geographical range.

  6. Beluga (Delphinapterus leucas) granulocytes and monocytes display variable responses to in vitro pressure exposures.

    Science.gov (United States)

    Thompson, Laura A; Romano, Tracy A

    2015-01-01

    While it is widely known that marine mammals possess adaptations which allow them to make repetitive and extended dives to great depths without suffering ill effects seen in humans, the response of marine mammal immune cells to diving is unknown. Renewed interest in marine mammal dive physiology has arisen due to reports of decompression sickness-like symptoms and embolic damage in stranded and by-caught animals, and there is concern over whether anthropogenic activities can impact marine mammal health by disrupting adaptive dive responses and behavior. This work addresses the need for information concerning marine mammal immune function during diving by evaluating granulocyte and monocyte phagocytosis, and granulocyte activation in belugas (n = 4) in comparison with humans (n = 4), with and without in vitro pressure exposures. In addition, the potential for additional stressors to impact immune function was investigated by comparing the response of beluga cells to pressure between baseline and stressor conditions. Granulocyte and monocyte phagocytosis, as well as granulocyte activation, were compared between pressure exposed and non-exposed cells for each condition, between different pressure profiles and between conditions using mixed generalized linear models (α = 0.05). The effects of pressure varied between species as well by depth, compression/decompression rates, and length of exposures, and condition for belugas. Pressure induced changes in granulocyte and monocyte function in belugas could serve a protective function against dive-related pathologies and differences in the response between humans and belugas could reflect degrees of dive adaptation. The alteration of these responses during physiologically challenging conditions may increase the potential for dive-related in jury and disease in marine mammals.

  7. Beluga (Delphinapterus leucas granulocytes and monocytes display variable responses to in vitro pressure exposures

    Directory of Open Access Journals (Sweden)

    Laura A Thompson

    2015-05-01

    Full Text Available While it is widely known that marine mammals possess adaptations which allow them to make repetitive and extended dives to great depths without suffering ill effects seen in humans, the response of marine mammal immune cells to diving is unknown. Renewed interest in marine mammal dive physiology has arisen due to reports of decompression sickness-like symptoms and embolic damage in stranded and by-caught animals, and there is concern over whether anthropogenic activities can impact marine mammal health by disrupting adaptive dive responses and behavior. This work addresses the need for information concerning marine mammal immune function during diving by evaluating granulocyte and monocyte phagocytosis, and granulocyte activation in belugas (n=4 in comparison with humans (n=4, with and without in vitro pressure exposures. In addition, the potential for additional stressors to impact immune function was investigated by comparing the response of beluga cells to pressure between baseline and stressor conditions. Granulocyte and monocyte phagocytosis, as well as granulocyte activation, were compared between pressure exposed and non-exposed cells for each condition, between different pressure profiles and between conditions using mixed generalized linear models (α=0.05. The effects of pressure varied between species as well by depth, compression/decompression rates, and length of exposures, and condition for belugas. Pressure induced changes in granulocyte and monocyte function in belugas could serve a protective function against dive-related pathologies and differences in the response between humans and belugas could reflect degrees of dive adaptation. The alteration of these responses during physiologically challenging conditions may increase the potential for dive-related in jury and disease in marine mammals.

  8. Response of birds to climatic variability; evidence from the western fringe of Europe.

    Science.gov (United States)

    Donnelly, Alison; Cooney, Tom; Jennings, Eleanor; Buscardo, Erika; Jones, Mike

    2009-05-01

    Ireland's geographic location on the western fringe of the European continent, together with its island status and impoverished avifauna, provides a unique opportunity to observe changes in bird migration and distribution patterns in response to changing climatic conditions. Spring temperatures have increased in western Europe over the past 30 years in line with reported global warming. These have been shown, at least in part, to be responsible for changes in the timing of life cycle events (phenology) of plants and animals. In order to investigate the response of bird species in Ireland to changes in temperature, we examined ornithological records of trans-Saharan migrants over the 31-year period 1969-1999. Analysis of the data revealed that two discrete climatic phenomena produced different responses in summer migrant bird species. Firstly, a number of long-distance migrants showed a significant trend towards earlier arrival. This trend was evident in some species and was found to be a response to increasing spring air temperature particularly in the month of March. Secondly, (1) a step change in the pattern of occurrences of non-breeding migrant bird species, and (2) an increase in the ringing data of migrant species were found to correlate with a step change in temperature in 1987-1988. These results indicate that, for migrant bird species, the impact of a sudden change in temperature can be as important as any long-term monotonic trend, and we suggest that the impact of step change events merits further investigation on a wider range of species and across a greater geographical range.

  9. Spatial variability of the response to climate change in regional groundwater systems -- examples from simulations in the Deschutes Basin, Oregon

    Science.gov (United States)

    Waibel, Michael S.; Gannett, Marshall W.; Chang, Heejun; Hulbe, Christina L.

    2013-01-01

    We examine the spatial variability of the response of aquifer systems to climate change in and adjacent to the Cascade Range volcanic arc in the Deschutes Basin, Oregon using downscaled global climate model projections to drive surface hydrologic process and groundwater flow models. Projected warming over the 21st century is anticipated to shift the phase of precipitation toward more rain and less snow in mountainous areas in the Pacific Northwest, resulting in smaller winter snowpack and in a shift in the timing of runoff to earlier in the year. This will be accompanied by spatially variable changes in the timing of groundwater recharge. Analysis of historic climate and hydrologic data and modeling studies show that groundwater plays a key role in determining the response of stream systems to climate change. The spatial variability in the response of groundwater systems to climate change, particularly with regard to flow-system scale, however, has generally not been addressed in the literature. Here we simulate the hydrologic response to projected future climate to show that the response of groundwater systems can vary depending on the location and spatial scale of the flow systems and their aquifer characteristics. Mean annual recharge averaged over the basin does not change significantly between the 1980s and 2080s climate periods given the ensemble of global climate models and emission scenarios evaluated. There are, however, changes in the seasonality of groundwater recharge within the basin. Simulation results show that short-flow-path groundwater systems, such as those providing baseflow to many headwater streams, will likely have substantial changes in the timing of discharge in response changes in seasonality of recharge. Regional-scale aquifer systems with flow paths on the order of many tens of kilometers, in contrast, are much less affected by changes in seasonality of recharge. Flow systems at all spatial scales, however, are likely to reflect

  10. The AGT Gene M235T Polymorphism and Response of Power-Related Variables to Aerobic Training

    Directory of Open Access Journals (Sweden)

    Zarębska Aleksandra, Jastrzębski Zbigniew, Moska Waldemar, Leońska-Duniec Agata, Kaczmarczyk Mariusz, Sawczuk Marek, Maciejewska-Skrendo Agnieszka, Żmijewski Piotr, Ficek Krzysztof, Trybek Grzegorz, Lulińska-Kuklik Ewelina, Ekaterina A. Semenova, Ildus I. Ahmetov, Cięszczyk Paweł

    2016-12-01

    Full Text Available The C allele of the M235T (rs699 polymorphism of the AGT gene correlates with higher levels of angiotensin II and has been associated with power and strength sport performance. The aim of the study was to investigate whether or not selected power-related variables and their response to a 12-week program of aerobic dance training are modulated by the AGT M235T genotype in healthy participants. Two hundred and one Polish Caucasian women aged 21 ± 1 years met the inclusion criteria and were included in the study. All women completed a 12-week program of low and high impact aerobics. Wingate peak power and total work capacity, 5 m, 10 m, and 30 m running times and jump height and jump power were determined before and after the training programme. All power-related variables improved significantly in response to aerobic dance training. We found a significant association between the M235T polymorphism and jump-based variables (squat jump (SJ height, p = 0.005; SJ power, p = 0.015; countermovement jump height, p = 0.025; average of 10 countermovement jumps with arm swing (ACMJ height, p = 0.001; ACMJ power, p = 0.035. Specifically, greater improvements were observed in the C allele carriers in comparison with TT homozygotes. In conclusion, aerobic dance, one of the most commonly practiced adult fitness activities in the world, provides sufficient training stimuli for augmenting the explosive strength necessary to increase vertical jump performance. The AGT gene M235T polymorphism seems to be not only a candidate gene variant for power/strength related phenotypes, but also a genetic marker for predicting response to training.

  11. Role of cell-to-cell variability in activating a positive feedback antiviral response in human dendritic cells.

    Directory of Open Access Journals (Sweden)

    Jianzhong Hu

    Full Text Available In the first few hours following Newcastle disease viral infection of human monocyte-derived dendritic cells, the induction of IFNB1 is extremely low and the secreted type I interferon response is below the limits of ELISA assay. However, many interferon-induced genes are activated at this time, for example DDX58 (RIGI, which in response to viral RNA induces IFNB1. We investigated whether the early induction of IFNBI in only a small percentage of infected cells leads to low level IFN secretion that then induces IFN-responsive genes in all cells. We developed an agent-based mathematical model to explore the IFNBI and DDX58 temporal dynamics. Simulations showed that a small number of early responder cells provide a mechanism for efficient and controlled activation of the DDX58-IFNBI positive feedback loop. The model predicted distributions of single cell responses that were confirmed by single cell mRNA measurements. The results suggest that large cell-to-cell variation plays an important role in the early innate immune response, and that the variability is essential for the efficient activation of the IFNB1 based feedback loop.

  12. Physiological response in the European flounder (Platichthys flesus) to variable salinity and oxygen conditions

    DEFF Research Database (Denmark)

    Lundgreen, Kim; Kiilerich, Pia; Tipsmark, Christian Kølbæk

    2008-01-01

    Physiological mechanisms involved in acclimation to variable salinity and oxygen levels and their interaction were studied in European flounder. The fish were acclimated for two weeks to freshwater (1 ‰ salinity), brackish water (11 ‰) or full strength seawater (35 ‰) under normoxic conditions...... (water Po2 = 158 mmHg) and then subjected to 48 h of continued normoxia or hypoxia at a level (Po2 = 54 mmHg) close to but above the critical Po2. Plasma osmolality, [Na+] and [Cl-] increased with increasing salinity, but the rises were limited, reflecting an effective extracellular osmoregulation....... Muscle water content was the same at all three salinities, indicating complete cell volume regulation. Gill Na+/K+-ATPase activity did not change with salinity, but hypoxia caused a 25 % decrease in branchial Na+/K+-ATPase activity at all three salinities. Furthermore, hypoxia induced a significant...

  13. Feasibility demonstration of a variable frequency driver-microwave transient regression rate measurement system. [for solid propellant combustion response

    Science.gov (United States)

    Strand, L. D.; Mcnamara, R. P.

    1976-01-01

    The feasibility of a system capable of rapidly and directly measuring the low-frequency (motor characteristics length bulk mode) combustion response characteristics of solid propellants has been investigated. The system consists of a variable frequency oscillatory driver device coupled with an improved version of the JPL microwave propellant regression rate measurement system. The ratio of the normalized regression rate and pressure amplitudes and their relative phase are measured as a function of varying pressure level and frequency. Test results with a well-characterized PBAN-AP propellant formulation were found to compare favorably with the results of more conventional stability measurement techniques.

  14. The Effect of Forging Variables on the Supersolvus Heat-Treatment Response of Powder-Metallurgy Nickel-Base Superalloys

    Science.gov (United States)

    2014-12-01

    AFRL-RX-WP-JA-2015-0160 THE EFFECT OF FORGING VARIABLES ON THE SUPERSOLVUS HEAT-TREATMENT RESPONSE OF POWDER-METALLURGY NICKEL -BASE SUPERALLOYS...POWDER-METALLURGY NICKEL - BASE SUPERALLOYS (POSTPRINT) 5a. CONTRACT NUMBER In-house 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 62102F 6. AUTHOR...of Powder-Metallurgy Nickel -Base Superalloys S.L. SEMIATIN, J.M. SHANK, A.R. SHIVELEY, W.M. SAURBER, E.F. GAUSSA, and A.L. PILCHAK The effect of

  15. The AGT Gene M235T Polymorphism and Response of Power-Related Variables to Aerobic Training

    Science.gov (United States)

    Aleksandra, Zarębska; Zbigniew, Jastrzębski; Waldemar, Moska; Agata, Leońska-Duniec; Mariusz, Kaczmarczyk; Marek, Sawczuk; Agnieszka, Maciejewska-Skrendo; Piotr, Żmijewski; Krzysztof, Ficek; Grzegorz, Trybek; Ewelina, Lulińska-Kuklik; Semenova, Ekaterina A.; Ahmetov, Ildus I.; Paweł, Cięszczyk

    2016-01-01

    The C allele of the M235T (rs699) polymorphism of the AGT gene correlates with higher levels of angiotensin II and has been associated with power and strength sport performance. The aim of the study was to investigate whether or not selected power-related variables and their response to a 12-week program of aerobic dance training are modulated by the AGT M235T genotype in healthy participants. Two hundred and one Polish Caucasian women aged 21 ± 1 years met the inclusion criteria and were included in the study. All women completed a 12-week program of low and high impact aerobics. Wingate peak power and total work capacity, 5 m, 10 m, and 30 m running times and jump height and jump power were determined before and after the training programme. All power-related variables improved significantly in response to aerobic dance training. We found a significant association between the M235T polymorphism and jump-based variables (squat jump (SJ) height, p = 0.005; SJ power, p = 0.015; countermovement jump height, p = 0.025; average of 10 countermovement jumps with arm swing (ACMJ) height, p = 0.001; ACMJ power, p = 0.035). Specifically, greater improvements were observed in the C allele carriers in comparison with TT homozygotes. In conclusion, aerobic dance, one of the most commonly practiced adult fitness activities in the world, provides sufficient training stimuli for augmenting the explosive strength necessary to increase vertical jump performance. The AGT gene M235T polymorphism seems to be not only a candidate gene variant for power/strength related phenotypes, but also a genetic marker for predicting response to training. Key points Aerobic dance provides sufficient training stimuli for the improvement of explosive power. The AGT gene M235T polymorphism is associated with individual variation in the change of power-related phenotypes in response to aerobic dance training. The C allele carriers of the AGT gene M235T polymorphism show greater improvements of jump

  16. An analysis of sequence variability in eight genes putatively involved in drought response in sunflower (Helianthus annuus L.).

    Science.gov (United States)

    Giordani, T; Buti, M; Natali, L; Pugliesi, C; Cattonaro, F; Morgante, M; Cavallini, A

    2011-04-01

    With the aim to study variability in genes involved in ecological adaptations, we have analysed sequence polymorphisms of eight unique genes putatively involved in drought response by isolation and analysis of allelic sequences in eight inbred lines of sunflower of different origin and phenotypic characters and showing different drought response in terms of leaf relative water content (RWC). First, gene sequences were amplified by PCR on genomic DNA from a highly inbred line and their products were directly sequenced. In the absence of single nucleotide polymorphisms, the gene was considered as unique. Then, the same PCR reaction was performed on genomic DNAs of eight inbred lines to isolate allelic variants to be compared. The eight selected genes encode a dehydrin, a heat shock protein, a non-specific lipid transfer protein, a z-carotene desaturase, a drought-responsive-element-binding protein, a NAC-domain transcription regulator, an auxin-binding protein, and an ABA responsive-C5 protein. Nucleotide diversity per synonymous and non-synonymous sites was calculated for each gene sequence. The π (a)/π (s) ratio range was usually very low, indicating strong purifying selection, though with locus-to-locus differences. As far as non-coding regions, the intron showed a larger variability than the other regions only in the case of the dehydrin gene. In the other genes tested, in which one or more introns occur, variability in the introns was similar or even lower than in the other regions. On the contrary, 3'-UTRs were usually more variable than the coding regions. Linkage disequilibrium in the selected genes decayed on average within 1,000 bp, with large variation among genes. A pairwise comparison between genetic distances calculated on the eight genes and the difference in RWC showed a significant correlation in the first phases of drought stress. The results are discussed in relation to the function of analysed genes, i.e. involved in gene regulation and signal

  17. Cholera and shigellosis: different epidemiology but similar responses to climate variability.

    Directory of Open Access Journals (Sweden)

    Benjamin A Cash

    Full Text Available Comparative studies of the associations between different infectious diseases and climate variability, such as the El Niño-Southern Oscillation, are lacking. Diarrheal illnesses, particularly cholera and shigellosis, provide an important opportunity to apply a comparative approach. Cholera and shigellosis have significant global mortality and morbidity burden, pronounced differences in transmission pathways and pathogen ecologies, and there is an established climate link with cholera. In particular, the specific ecology of Vibrio cholerae is often invoked to explain the sensitivity of that disease to climate.The extensive surveillance data of the International Center for Diarrheal Disease Research, Bangladesh are used here to revisit the known associations between cholera and climate, and to address their similarity to previously unexplored patterns for shigellosis. Monthly case data for both the city of Dhaka and a rural area known as Matlab are analyzed with respect to their association with El Niño and flooding. Linear correlations are examined between flooding and cumulative cases, as well as for flooding and El Niño. Rank-correlation maps are also computed between disease cases in the post-monsoon epidemic season and sea surface temperatures in the Pacific. Similar climate associations are found for both diseases and both locations. Increased cases follow increased monsoon flooding and increased sea surface temperatures in the preceding winter corresponding to an El Niño event.The similarity in association patterns suggests a systemic breakdown in population health with changing environmental conditions, in which climate variability acts primarily through increasing the exposure risk of the human population. We discuss these results in the context of the on-going debate on the relative importance of the environmental reservoir vs. secondary transmission, as well as the implications for the use of El Niño as an early indicator of

  18. Biosorption and biodegradation of a sulfur dye in high-strength dyeing wastewater by Acidithiobacillus thiooxidans.

    Science.gov (United States)

    Nguyen, Thai Anh; Fu, Chun-Chieh; Juang, Ruey-Shin

    2016-11-01

    The ability of the bacterial strain Acidithiobacillus thiooxidans to remove sulfur blue 15 (SB15) dye from water samples was examined. This bacterium could not only oxidize sulfur compounds to sulfuric acid but also promote the attachment of the cells to the surface of sulfidic particles, therefore serving as an efficient biosorbent. The biosorption isotherms were better described by the Langmuir equation than by the Freundlich or Dubinin-Radushkevich equation. Also, the biosorption process followed the pseudo-second-order kinetics. At pH 8.3 and SB15 concentrations up to 2000 mg L(-1) in the biomass/mineral salt solution, the dye removal and decolorization were 87.5% and 91.4%, respectively, following the biosorption process. Biodegradation was proposed as a subsequent process for the remaining dye (250-350 mg L(-1)). A central composite design was used to analyze independent variables in the response surface methodology study. Under the optimal conditions (i.e., initial dye concentration of 300 mg L(-1), initial biomass concentration of 1.0 g L(-1), initial pH of 11.7, and yeast extract dose of 60 mg L(-1)), up to 50% of SB15 was removed after 4 days of biodegradation.

  19. Exploring the variability of single trials in somatosensory evoked responses using constrained source extraction and RMT.

    Science.gov (United States)

    Koutras, A; Kostopoulos, G K; Ioannides, A A

    2008-03-01

    This paper describes the theoretical background of a new data-driven approach to encephalographic single-trial (ST) data analysis. Temporal constrained source extraction using sparse decomposition identifies signal topographies that closely match the shape characteristics of a reference signal, one response for each ST. The correlations between these ST topographies are computed for formal Correlation Matrix Analysis (CMA) based on Random Matrix Theory (RMT). The RMT-CMA provides clusters of similar ST topologies in a completely unsupervised manner. These patterns are then classified into deterministic set and noise using well established RMT results. The efficacy of the method is applied to EEG and MEG data of somatosensory evoked responses (SERs). The results demonstrate that the method can recover brain signals with time course resembling the reference signal and follow changes in strength and/or topography in time by simply stepping the reference signal through time.

  20. Semiarid watershed response in central New Mexico and its sensitivity to climate variability and change

    Directory of Open Access Journals (Sweden)

    E. R. Vivoni

    2009-06-01

    Full Text Available Hydrologic processes in the semiarid regions of the Southwest United States are considered to be highly susceptible to variations in temperature and precipitation characteristics due to the effects of climate change. Relatively little is known about the potential impacts of climate change on the basin hydrologic response, namely streamflow, evapotranspiration and recharge, in the region. In this study, we present the development and application of a continuous, semi-distributed watershed model for climate change studies in semiarid basins of the Southwest US. Our objective is to capture hydrologic processes in large watersheds, while accounting for the spatial and temporal variations of climate forcing and basin properties in a simple fashion. We apply the model to the Río Salado basin in central New Mexico since it exhibits both a winter and summer precipitation regime and has a historical streamflow record for model testing purposes. Subsequently, we use a sequence of climate change scenarios that capture observed trends for winter and summer precipitation, as well as their interaction with higher temperatures, to perform long-term ensemble simulations of the basin response. Results of the modeling exercise indicate that precipitation uncertainty is amplified in the hydrologic response, in particular for processes that depend on a soil saturation threshold. We obtained substantially different hydrologic sensitivities for winter and summer precipitation ensembles, indicating a greater sensitivity to more intense summer storms as compared to more frequent winter events. In addition, the impact of changes in precipitation characteristics overwhelmed the effects of increased temperature in the study basin. Nevertheless, combined trends in precipitation and temperature yield a more sensitive hydrologic response throughout the year.

  1. Effects of Variable Helmet Weight on Human Response to -Gx Impact

    Science.gov (United States)

    2016-02-01

    properties. Test programs conducted by Perry, Buhrman, and associates [1,6,7,8,10] at the Air Force Research Laboratory’s former Biomechanics Branch...statistical analysis. The measured headrest pre-impact loads were statistically evaluated for all of the test runs . The headrest pre-impact load is...Appendix A. 4.1 Acceleration Response Test runs that were greater than 2.5 standard deviations from the mean were identified and removed from the

  2. Variability in individual and group responses in feeding behaviour of iceland scallop; chlamys islandica.

    OpenAIRE

    Habbestad, Terese

    2012-01-01

    Due to regulatory requirements of monitoring the marine environment, and the development of offshore petroleum activities in new and more remote locations, there is at present an emphasis on implementing biological responses in monitoring systems to reflect the environmental conditions over a period of time. Choosing Darwinian fitness parameters that reflect the health status of individuals, such as growth and reproductive potential is highly interesting. The current study used clearance ...

  3. Variability or conservation of hepatitis C virus hypervariable region 1? Implications for immune responses

    Indian Academy of Sciences (India)

    Mario U Mondelli; Antonella Cerino; Annalisa Meola; Alfredo Nicosia

    2003-04-01

    The hypervariable region 1 (HVR1) of the E2 protein of hepatitis C virus (HCV) is highly heterogeneous in its primary sequence and is responsible for significant inter- and intra-individual variation of the infecting virus, which may represent an important pathogenetic mechanism leading to immune escape and persistent infection. A binding site for neutralizing antibodies (Ab) has also been allegedly identified in this region. Prospective studies of serological responses to synthetic oligopeptides derived from naturally-occurring HVR1 sequences showed promiscuous recognition of HVR1 variants in most patients via binding to C-terminal amino acid residues with conserved physicochemical properties. Monoclonal antibodies generated by immunization of mice with peptides derived from natural HVR1 sequences were shown to recognize several HVR1 variants in line with evidence gathered from studies using human sera. In addition, selected mAbs were able to bind HVR1 in the context of a complete soluble form of the E2 glycoprotein, indicating recognition of correctly folded sequences, and were shown to specifically capture circulating and recombinant HCV particles, suggesting that HVR1 is expressed on intact virus particles and therefore potentially able to interact with cellular receptor(s). These findings suggest that it is possible to induce a broadly reactive clonal immune response to multiple HCV variants and that this mechanism could be used in principle to induce protective immunity for a large repertoire of HCV variants.

  4. Biodegradable congress 2012; Bioschmierstoff-Kongress 2012

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2012-11-01

    Within the Guelzower expert discussions at 5th and 6th June, 2012 in Oberhausen (Federal Republic of Germany) the following lectures were held: (1) Promotion of biodegradable lubricants by means of research and development as well as public relations (Steffen Daebeler); (2) Biodegradable lubricants - An overview of the advantages and disadvantages of the engaged product groups (Hubertus Murrenhoff); (3) Standardization of biodegradable lubricants - CEN/DIN standard committees - state of the art (Rolf Luther); (4) Market research for the utilization of biodegradable lubricants and means of proof of sustainability (Norbert Schmitz); (5) Fields of application for high performance lubricants and requirements upon the products (Gunther Kraft); (6) Investigations of biodegradable lubricants in rolling bearings and gears (Christoph Hentschke); (7) Biodegradable lubricants in central lubrication systems Development of gears and bearings of offshore wind power installations (Reiner Wagner); (8) Investigations towards environmental compatibility of biodegradable lubricants used in offshore wind power installations (Tolf Schneider); (9) Development of glycerine based lubricants for the industrial metalworking (Harald Draeger); (10) Investigations and utilization of biodegradable oils as electroinsulation oils in transformers (Stefan Tenbohlen); (11) Operational behaviour of lubricant oils in vegetable oil operation and Biodiesel operation (Horst Hamdorf); (12) Lubrication effect of lubricating oil of the third generation (Stefan Heitzig); (13) Actual market development from the view of a producer of biodegradable lubricants (Frank Lewen); (14) Utilization of biodegradable lubricants in forestry harvesters (Guenther Weise); (15) New biodegradable lubricants based on high oleic sunflower oil (Otto Botz); (16) Integrated fluid concept - optimized technology and service package for users of biodegradable lubricants (Juergen Baer); (17) Utilization of a bio oil sensor to control

  5. Risk factors for breakage of biodegradable plate systems after bilateral sagittal split mandibular setback surgery.

    Science.gov (United States)

    Yoshioka, Izumi; Igawa, Kaori; Nagata, Jyunko; Yoshida, Maho; Baba, Takashi; Ichiki, Takeshi; Kondoh, Yudai; Takamori, Koichi; Kashima, Koji; Sakoda, Sumio

    2013-06-01

    The aim of this retrospective study was to evaluate the risk factors associated with breakage of biodegradable plate systems after bilateral sagittal split mandibular setback. We studied 169 Japanese adults (62 men, 107 women; age range 16-53 years) with deformities of the jaw diagnosed as mandibular prognathism. All patients were treated by bilateral sagittal split osteotomy (BSSO) with 2 biodegradable fixation plates and screws at the anterior mandibular ramus. We collected the following data from the medical records and radiological findings: sex; age; degree of setback; presence of asymmetry; presence of open bite; operation; design of the plate; operating time; and blood loss. Multiple logistic regression analysis was used to find the factors that were independently associated with the dependent variable: breakage of the biodegradable plate system. In 10 of the 169 patients (6%) the biodegradable plate system for the BSSO broke. Factors that influenced whether or not the biodegradable plate system fractured were if they were asymmetrical (odds ratio (OR) 5.35; P=0.02) and had an open bite (OR 5.20; P=0.02). Asymmetry or open bite was significantly associated with breaks in the biodegradable plate system. Biodegradable plates should be used only when loading is minimal.

  6. Effects of heart rate variability biofeedback on cardiovascular responses and autonomic sympathovagal modulation following stressor tasks in prehypertensives.

    Science.gov (United States)

    Chen, S; Sun, P; Wang, S; Lin, G; Wang, T

    2016-02-01

    Autonomic dysfunction is implicated in prehypertension, and previous studies have suggested that therapies that improve modulation of sympathovagal balance, such as biofeedback and slow abdominal breathing, are effective in patients with prehypertension at rest. However, considering that psychophysiological stressors may be associated with greater cardiovascular risk in prehypertensives, it is important to investigate whether heart rate variability biofeedback (HRV-BF) results in equivalent effects on autonomic cardiovascular responses control during stressful conditions in prehypertensives. A total of 32 college students with prehypertension were enrolled and randomly assigned to HRV-BF (n=12), slow abdominal breathing (SAB, n=10) or no treatment (control, n=10) groups. Then, a training experiment consisting of 15 sessions was employed to compare the effect of each intervention on the following cardiovascular response indicators before and after intervention: heart rate (HR); heart rate variability (HRV) components; blood volume pulse amplitude (BVPamp); galvanic skin response; respiration rate (RSP); and blood pressure. In addition, the cold pressor test and the mental arithmetic challenge test were also performed over two successive days before and after the invention as well as after 3 months of follow-up. A significant decrease in HR and RSP and a significant increase in BVPamp were observed after the HRV-BF intervention (P<0.001). For the HRV analysis, HRV-BF significantly reduced the ratio of low-frequency power to high-frequency power (the LF/HF ratio, P<0.001) and increased the normalized high-frequency power (HFnm) (P<0.001) during the stress tests, and an added benefit over SAB by improving HRV was also observed. In the 3-month follow-up study, similar effects on RSP, BVPamp, LF/HF and HFnm were observed in the HRV-BF group compared with the SAB group. HRV-BF training contributes to the beneficial effect of reducing the stress-related cardiovascular

  7. Ecohydrological responses of dense canopies to environmental variability: 2. Role of acclimation under elevated CO2

    Science.gov (United States)

    Drewry, D. T.; Kumar, P.; Long, S.; Bernacchi, C.; Liang, X.-Z.; Sivapalan, M.

    2010-12-01

    The ability to accurately predict land-atmosphere exchange of mass, energy, and momentum over the coming century requires the consideration of plant biochemical, ecophysiological, and structural acclimation to modifications of the ambient environment. Amongst the most important environmental changes experienced by terrestrial vegetation over the last century has been the increase in ambient carbon dioxide (CO2) concentrations, with a projected doubling in CO2 from preindustrial levels by the middle of this century. This change in atmospheric composition has been demonstrated to significantly alter a variety of leaf and plant properties across a range of species, with the potential to modify land-atmosphere interactions and their associated feedbacks. Free Air Carbon Enrichment (FACE) technology has provided significant insight into the functioning of vegetation in natural conditions under elevated CO2, but remains limited in its ability to quantify the exchange of CO2, water vapor, and energy at the canopy scale. This paper addresses the roles of ecophysiological, biochemical, and structural plant acclimation on canopy-scale exchange of CO2, water vapor, and energy through the application of a multilayer canopy-root-soil model (MLCan) capable of resolving changes induced by elevated CO2 through the canopy and soil systems. Previous validation of MLCan flux estimates were made for soybean and maize in the companion paper using a record of six growing seasons of eddy covariance data from the Bondville Ameriflux site. Observations of leaf-level photosynthesis, stomatal conductance, and surface temperature collected at the SoyFACE experimental facility in central Illinois provide a basis for examining the ability of MLCan to capture vegetation responses to an enriched CO2 environment. Simulations of control (370 [ppm]) and elevated (550 [ppm]) CO2 environments allow for an examination of the vertical variation and canopy-scale responses of vegetation states and fluxes

  8. Assessment of Hydrologic Response to Variable Precipitation Forcing: Russian River Case Study

    Science.gov (United States)

    Cifelli, R.; Hsu, C.; Johnson, L. E.

    2014-12-01

    NOAA Hydrometeorology Testbed (HMT) activities in California have involved deployment of advanced sensor networks to better track atmospheric river (AR) dynamics and inland penetration of high water vapor air masses. Numerical weather prediction models and decision support tools have been developed to provide forecasters a better basis for forecasting heavy precipitation and consequent flooding. The HMT also involves a joint project with California Department of Water Resources (CA-DWR) and the Scripps Institute for Oceanography (SIO) as part of CA-DWR's Enhanced Flood Response and Emergency Preparedness (EFREP) program. The HMT activities have included development and calibration of a distributed hydrologic model, the NWS Office of Hydrologic Development's (OHD) Research Distributed Hydrologic Model (RDHM), to prototype the distributed approach for flood and other water resources applications. HMT has applied RDHM to the Russian-Napa watersheds for research assessment of gap-filling weather radars for precipitation and hydrologic forecasting and for establishing a prototype to inform both the NWS Monterey Forecast Office and the California Nevada River Forecast Center (CNRFC) of RDHM capabilities. In this presentation, a variety of precipitation forcings generated with and without gap filling radar and rain gauge data are used as input to RDHM to assess the hydrologic response for selected case study events. Both the precipitation forcing and hydrologic model are run at different spatial and temporal resolution in order to examine the sensitivity of runoff to the precipitation inputs. Based on the timing of the events and the variations of spatial and temporal resolution, the parameters which dominate the hydrologic response are identified. The assessment is implemented at two USGS stations (Ukiah near Russian River and Austin Creek near Cazadero) that are minimally influenced by managed flows and objective evaluation can thus be derived. The results are assessed

  9. Plasma biochemical variables in response to 42-km kayak and canoe races.

    Science.gov (United States)

    Lutoslawska, G; Sendecki, W

    1990-12-01

    Some plasma biochemical parameters were examined one day prior, immediately after and 18 h after 42-km canoe and kayak races. The increases in plasma glycerol, lactate, ammonia and uric acid as well as the elevation in plasma CK, LDH and transaminase activities confirm the changes induced by different prolonged efforts. However some differences between canoeists and kayakers were indicated for ammonia and urea plasma concentration after the race, lactate elimination and increase in CK and transaminase activities. The influence of body posture and the impact of the static component during effort are discussed as a reason for observed disparity in response to prolonged races.

  10. Optimization of process variables on flexural properties of epoxy/organo-montmorillonite nanocomposite by response surface methodology

    Directory of Open Access Journals (Sweden)

    2008-01-01

    Full Text Available This study attempted to investigate the preparation and optimization of the flexural properties for epoxy/organomontmorillonite (OMMT nanocomposites. In-situ polymerization method was used to prepare epoxy/OMMT nanocomposites. The diglycidyl ether bisphenol A (DGEBA and curing agent were mixed first, followed by the addition of OMMT. In this study, computer aided statistical methods of experimental design (Response Surface Methodology, RSM was used to investigate the process variables on the flexural properties of epoxy/4wt% OMMT nanocomposites. Speed of mechanical stirrer, post-curing time and post-curing temperature were chosen as process variables in the experimental design. Results showed that the speed of mechanical stirrer, post-curing time and post-curing temperature were able to influence the flexural modulus and flexural yield stress of epoxy/4 wt% OMMT nanocomposites. The results of optimization showed that the design of experiment (DOE has six combination of operating variables which have been obtained in order to attain the greatest overall desirability.

  11. Variability in prefrontal hemodynamic response during exposure to repeated self-selected music excerpts, a near-infrared spectroscopy study.

    Science.gov (United States)

    Moghimi, Saba; Schudlo, Larissa; Chau, Tom; Guerguerian, Anne-Marie

    2015-01-01

    Music-induced brain activity modulations in areas involved in emotion regulation may be useful in achieving therapeutic outcomes. Clinical applications of music may involve prolonged or repeated exposures to music. However, the variability of the observed brain activity patterns in repeated exposures to music is not well understood. We hypothesized that multiple exposures to the same music would elicit more consistent activity patterns than exposure to different music. In this study, the temporal and spatial variability of cerebral prefrontal hemodynamic response was investigated across multiple exposures to self-selected musical excerpts in 10 healthy adults. The hemodynamic changes were measured using prefrontal cortex near infrared spectroscopy and represented by instantaneous phase values. Based on spatial and temporal characteristics of these observed hemodynamic changes, we defined a consistency index to represent variability across these domains. The consistency index across repeated exposures to the same piece of music was compared to the consistency index corresponding to prefrontal activity from randomly matched non-identical musical excerpts. Consistency indexes were significantly different for identical versus non-identical musical excerpts when comparing a subset of repetitions. When all four exposures were compared, no significant difference was observed between the consistency indexes of randomly matched non-identical musical excerpts and the consistency index corresponding to repetitions of the same musical excerpts. This observation suggests the existence of only partial consistency between repeated exposures to the same musical excerpt, which may stem from the role of the prefrontal cortex in regulating other cognitive and emotional processes.

  12. Variability of shelf sea pH and surface water CO2 in response to North Atlantic Oscillation forcing

    Science.gov (United States)

    Salt, L.; Thomas, H.; Prowe, A. E. F.; Borges, A. V.; de Baar, H. J. W.

    2012-04-01

    High biological activity causes a distinct seasonality of surface water pH in the North Sea, which has been identified as a strong sink for atmospheric CO2 via a particularly effective shelf pump. The intimate connection between the North Sea and the North Atlantic suggests that the variability of the CO2 system of the North Atlantic Ocean may in part be responsible for the observed, but hitherto poorly understood variability of pH and CO2 in the North Sea. Here we investigate the role of the North Atlantic Oscillation (NAO), the dominant climate mode for the North Atlantic hemisphere in governing this variability. Based on three extensive observational records covering the relevant levels of the NAO index, we provide evidence that the North Sea pH and CO2 system strongly responds to external and internal expressions of the NAO. We argue that under NAO+ conditions higher rates of inflow of water from the North Atlantic Ocean limits seasonal shoaling of the summer mixed layer in the northern North Sea, diminishing the biological potential to lower pCO2 and raise pH. In addition the faster circulation of the North Sea enhances the shelf pump efficiency. These clear patterns are obscured by changing properties of the North Sea waters, masking or enforcing these effects on various time scales. Such controls indicate that inter-annual trends in the North Sea CO2 system must be carefully examined with consideration to the North Atlantic Oscillation.

  13. Extremophiles in Mineral Sulphide Heaps: Some Bacterial Responses to Variable Temperature, Acidity and Solution Composition

    Directory of Open Access Journals (Sweden)

    Helen R. Watling

    2015-07-01

    Full Text Available In heap bioleaching, acidophilic extremophiles contribute to enhanced metal extraction from mineral sulphides through the oxidation of Fe(II and/or reduced inorganic sulphur compounds (RISC, such as elemental sulphur or mineral sulphides, or the degradation of organic compounds derived from the ore, biota or reagents used during mineral processing. The impacts of variable solution acidity and composition, as well as temperature on the three microbiological functions have been examined for up to four bacterial species found in mineral sulphide heaps. The results indicate that bacteria adapt to sufficiently high metal concentrations (Cu, Ni, Co, Zn, As to allow them to function in mineral sulphide heaps and, by engaging alternative metabolic pathways, to extend the solution pH range over which growth is sustained. Fluctuating temperatures during start up in sulphide heaps pose the greatest threat to efficient bacterial colonisation. The large masses of ores in bioleaching heaps mean that high temperatures arising from sulphide oxidation are hard to control initially, when the sulphide content of the ore is greatest. During that period, mesophilic and moderately thermophilic bacteria are markedly reduced in both numbers and activity.

  14. Poly (3-Hydroxyalkanoates): Biodegradable Plastics

    OpenAIRE

    2013-01-01

    During the 1920’s, a polyester called poly (3-hydroxybutyrate) was discovered in bacterial cells. This compound, otherwise known as PHB, is part of a polyester family called polyhydroxyalkanoates (PHAs). Polyhydroxyalkanoates are used as an energy and carbon sto rage compound within certain bacterial cells. Polyhydroxyalkanoates (PHAs) are thermoplastic, biodegradable polyesters synthesized by some bacteria from rene...

  15. Biodegradable polymeric prodrugs of naltrexone

    NARCIS (Netherlands)

    Bennet, D.B.; Li, X.; Adams, N.W.; Kim, S.W.; Hoes, C.J.T.; Feijen, J.

    1991-01-01

    The development of a biodegradable polymeric drug delivery system for the narcotic antagonist naltrexone may improve patient compliance in the treatment of opiate addiction. Random copolymers consisting of the ¿-amino acids N5-(3-hydroxypropyl--glutamine and -leucine were synthesized with equimolar

  16. Biodegradation kinetics at low concentrations (

    DEFF Research Database (Denmark)

    Toräng, Lars; Albrechtsen, Hans-Jørgen; Nyholm, Niels

    2000-01-01

    Aerobic biodegradation of 2,4-dichlorophenoxyacetic acid (2,4-D) was studied in groundwater added sediment fines. At concentrations at or below 1 mu g/L of 2,4-D degradation kinetic was of true first order without significant growth of specific degraders and with half-life for mineralization...

  17. Biodegradable Pectin/clay Aerogels

    Science.gov (United States)

    Biodegradable, foamlike materials based on renewable pectin and sodium montmorillonite clay were fabricated through a simple, environmentally friendly freeze-drying process. Addition of multivalent cations (Ca2+ and Al3+) resulted in apparent crosslinking of the polymer, and enhancement of aerogel p...

  18. Biodegradable polymer optical fiber (Conference Presentation)

    Science.gov (United States)

    Zhang, Chenji; Kalaba, Surge; Shan, Dingying; Xu, Kaitian; Yang, Jian; Liu, Zhiwen

    2016-10-01

    Biocompatible and even biodegradable polymers have unique advantages in various biomedical applications. Recent years, photonic devices fabricated using biocompatible polymers have been widely studied. In this work, we manufactured an optical fiber using biodegradable polymer POC and POMC. This step index optical fiber is flexible and easy to handle. Light was coupled into this polymer fiber by directly using objective. The fiber has a good light guiding property and an approximate loss of 2db/cm. Due to the two layer structure, our fiber is able to support applications inside biological tissue. Apart from remarkable optical performance, our fiber was also found capable of performing imaging. By measuring the impulse response of this multimode polymer fiber and using the linear inversion algorithm, concept proving experiments were completed. Images input into our fiber were able to be retrieved from the intensity distribution of the light at the output end. Experiment result proves the capability of our optical fiber to be used as a fiber endoscopy no needs to remove.

  19. A kinetic model for predicting biodegradation.

    Science.gov (United States)

    Dimitrov, S; Pavlov, T; Nedelcheva, D; Reuschenbach, P; Silvani, M; Bias, R; Comber, M; Low, L; Lee, C; Parkerton, T; Mekenyan, O

    2007-01-01

    Biodegradation plays a key role in the environmental risk assessment of organic chemicals. The need to assess biodegradability of a chemical for regulatory purposes supports the development of a model for predicting the extent of biodegradation at different time frames, in particular the extent of ultimate biodegradation within a '10 day window' criterion as well as estimating biodegradation half-lives. Conceptually this implies expressing the rate of catabolic transformations as a function of time. An attempt to correlate the kinetics of biodegradation with molecular structure of chemicals is presented. A simplified biodegradation kinetic model was formulated by combining the probabilistic approach of the original formulation of the CATABOL model with the assumption of first order kinetics of catabolic transformations. Nonlinear regression analysis was used to fit the model parameters to OECD 301F biodegradation kinetic data for a set of 208 chemicals. The new model allows the prediction of biodegradation multi-pathways, primary and ultimate half-lives and simulation of related kinetic biodegradation parameters such as biological oxygen demand (BOD), carbon dioxide production, and the nature and amount of metabolites as a function of time. The model may also be used for evaluating the OECD ready biodegradability potential of a chemical within the '10-day window' criterion.

  20. Pathological gambling and age: differences in personality, psychopathology, and response to treatment variables.

    Science.gov (United States)

    González-Ibáñez, A; Mora, M; Gutiérrez-Maldonado, J; Ariza, A; Lourido-Ferreira, M R

    2005-02-01

    The aim of this study was to ascertain the possible differences in personality, psychopathology, and response to treatment in pathological gambling according to age. The sample, comprising 67 participants, was divided into three groups: 32.6% with ages ranging between 17 and 26 years, 31.3% between 27 and 43 years, and 35.8% over 44 years of age. The participants were administered the following tests, Minnesota Multiphasic Personality Inventory [MMPI; Hathaway, S.R. & McKinley, J.C. (1943, 1961). Cuestionario de personalidad MMPI. Madrid Seccion de Estudios de TEA ed. 1970, 1975], sensation-seeking questionnaire [SSS; Zuckerman, M. (1979). Sensation seeking; beyond the optimal level of arousal. Hillsdale, NJ: Lawrence Erlbaum Associates], and the Symptom Check List Revised [SCL-90-R; Derogatis, L.R. (1977). Symptom check list-90 revised. Administration scoring and procedures manual. Baltimore]. All underwent a group treatment programme that was carried out in the Pathological Gambling Unit at Ciutat Sanitaria i Universitaria de Bellvitge (CSUB), Teaching hospital, Barcelona, Spain. The findings show differences depending on age in the participants' personality and in psychopathology and in their response to treatment.

  1. Relating the Variability of Tone-Burst Otoacoustic Emission and Auditory Brainstem Response Latencies to the Underlying Cochlear Mechanics

    Science.gov (United States)

    Verhulst, Sarah; Shera, Christopher A.

    2016-01-01

    Forward and reverse cochlear latency and its relation to the frequency tuning of the auditory filters can be assessed using tone bursts (TBs). Otoacoustic emissions (TBOAEs) estimate the cochlear roundtrip time, while auditory brainstem responses (ABRs) to the same stimuli aim at measuring the auditory filter buildup time. Latency ratios are generally close to two and controversy exists about the relationship of this ratio to cochlear mechanics. We explored why the two methods provide different estimates of filter buildup time, and ratios with large inter-subject variability, using a time-domain model for OAEs and ABRs. We compared latencies for twenty models, in which all parameters but the cochlear irregularities responsible for reflection-source OAEs were identical, and found that TBOAE latencies were much more variable than ABR latencies. Multiple reflection-sources generated within the evoking stimulus bandwidth were found to shape the TBOAE envelope and complicate the interpretation of TBOAE latency and TBOAE/ABR ratios in terms of auditory filter tuning. PMID:27175040

  2. Investigation of the prefrontal cortex in response to duration-variable anagram tasks using functional near-infrared spectroscopy

    Science.gov (United States)

    Tian, Fenghua; Chance, Britton; Liu, Hanli

    2009-09-01

    We hypothesize that nonlinearity between short-term anagram tasks and corresponding hemodynamic responses can be observed by functional near-infrared spectroscopy (fNIRS) in the prefrontal cortex (PFC). The PFC of six human subjects in response to anagram tasks is investigated using multichannel fNIRS. Concentration changes of oxyhemoglobin and deoxyhemoglobin in the PFC are measured with variable anagram durations and at two difficulty levels (four- and six-letter anagrams). The durations to perform the selected anagram tasks range from several seconds to more than one minute. The dorsolateral PFC areas exhibit consistent and strong hemodynamic deactivation during and shortly after task execution. The superposition principle of a linear system is employed to investigate nonlinear hemodynamic features among three task duration subgroups: D1 = 2.0 sec, D2 = 4.0 sec, and D3 = 8.0 sec. Such analysis shows clear nonlinearity in hemodynamic responses on the PFC with task durations shorter than 4 sec. Our observation of significant deactivation in early hemodynamic responses in the PFC is consistent with multiple fNIRS studies and several reports given in the field of functional magnetic resonance imaging. A better understanding of nonlinearity in fNIRS signals will have potential for us to investigate brain adaptation and to extrapolate neuronal activities from hemodynamic signals.

  3. Exploring the role of genetic variability and lifestyle in oxidative stress response for healthy aging and longevity.

    Science.gov (United States)

    Dato, Serena; Crocco, Paolina; D'Aquila, Patrizia; de Rango, Francesco; Bellizzi, Dina; Rose, Giuseppina; Passarino, Giuseppe

    2013-08-08

    Oxidative stress is both the cause and consequence of impaired functional homeostasis characterizing human aging. The worsening efficiency of stress response with age represents a health risk and leads to the onset and accrual of major age-related diseases. In contrast, centenarians seem to have evolved conservative stress response mechanisms, probably derived from a combination of a diet rich in natural antioxidants, an active lifestyle and a favorable genetic background, particularly rich in genetic variants able to counteract the stress overload at the level of both nuclear and mitochondrial DNA. The integration of these factors could allow centenarians to maintain moderate levels of free radicals that exert beneficial signaling and modulator effects on cellular metabolism. Considering the hot debate on the efficacy of antioxidant supplementation in promoting healthy aging, in this review we gathered the existing information regarding genetic variability and lifestyle factors which potentially modulate the stress response at old age. Evidence reported here suggests that the integration of lifestyle factors (moderate physical activity and healthy nutrition) and genetic background could shift the balance in favor of the antioxidant cellular machinery by activating appropriate defense mechanisms in response to exceeding external and internal stress levels, and thus possibly achieving the prospect of living a longer life.

  4. Self-Assembled Cationic Biodegradable Nanoparticles from pH-Responsive Amino-Acid-Based Poly(Ester Urea Urethane)s and Their Application As a Drug Delivery Vehicle.

    Science.gov (United States)

    He, Mingyu; Potuck, Alicia; Kohn, Julie C; Fung, Katharina; Reinhart-King, Cynthia A; Chu, Chih-Chang

    2016-02-01

    The objective of this study is to develop a new family of biodegradable and biologically active copolymers and their subsequent self-assembled cationic nanoparticles as better delivery vehicles for anticancer drugs to achieve the synergism between the cytotoxicity effects of the loaded drugs and the macrophage inflammatory response of the delivery vehicle. This family of cationic nanoparticles was formulated from a new family of amphiphilic cationic Arginine-Leucine (Arg-Leu)-based poly(ester urea urethane) (Arg-Leu PEUU) synthesized from four building blocks (amino acids, diols, glycerol α-monoallyl ether, and 1,6 hexamethylene diisocyanate). The chemical, physical, and biological properties of Arg-Leu PEUU biomaterials can be tuned by controlling the feed ratio of the four building blocks. The Arg-Leu PEUU copolymers have weight-average molecular weights from 13.4 to 16.8 kDa and glass-transition temperatures from -3.4 to -4.6 °C. The self-assembled cationic nanoparticles (Arg-Leu PEUU NPs) were prepared using a facile dialysis method. Arg-Leu PEUU NPs have average diameters ranging from 187 to 272 nm, show good biocompatibility with 3T3 fibroblasts, and they support bovine aortic endothelial cell (BAEC) proliferation and adhesion. Arg-Leu PEUU NPs also enhanced the macrophages' production of tumor necrosis factor-α (TNF-α) and nitric oxide (NO), but produced relatively low levels of interleukin-10 (IL-10), and therefore, the antitumor activity of macrophages might be enhanced. Arg-Leu PEUU NPs were taken up by HeLa cells after 4 h of incubation. The in vitro hemolysis assay showed the cationic Arg-Leu PEUU NPs increased their chance of endosomal escape at a more acidic pH. Doxorubicin (DOX) was successfully incorporated into the Arg-Leu PEUU NPs, and the DOX-loaded Arg-Leu PEUU NPs exhibited a pH-dependent drug release profile with accelerated release kinetics in a mild acidic condition. The DOX-loaded 6-Arg-4-Leu-4 A/L-2/1 NPs showed higher HeLa cell

  5. Coastal fish indicators response to natural and anthropogenic drivers-variability at temporal and different spatial scales

    Science.gov (United States)

    Bergström, L.; Bergström, U.; Olsson, J.; Carstensen, J.

    2016-12-01

    Ecological indicators are increasingly used in marine and freshwater management but only few are developed towards full operationalization with known patterns of variability and documented responses to natural and anthropogenic environmental drivers. Here, we evaluate potential sources of indicator variability at two different spatial scales in three coastal fish-based indicators of environmental status in the Baltic Sea; abundance of cyprinids, abundance of perch and the proportion of larger perch. The study was performed on a data set covering 41 monitoring areas subject to different levels of anthropogenic impact, at a latitudinal range of 56-66°N and a salinity range of 2-8. Interannual variation was clearly minor relative to spatial variation. Small-scale spatial variation was related to water depth, wave exposure and water temperature. The remaining variation was assessed in relation to differences in natural and anthropogenic drivers between monitoring areas. Cyprinids showed a clear inverse relationship to water transparency, which was used as a proxy for eutrophication, indicating increased abundances in nutrient enriched areas. None of the indicators showed an expected negative relationship to the level of coastal commercial fisheries catches. Rather, a positive relationship for Perch suggested that the coastal fisheries were concentrated to areas with strong perch populations in the studied areas. The effect of salinity and climate (temperature during the growth season) among monitoring areas were small. The results emphasize the importance of assigning area-specific boundary levels to define good environmental status in the coastal fish indicators, in order to account for natural sources of variability. Further, although long-term monitoring in reference areas is crucial for obtaining a historical baseline, our results suggest that the status assessment of coastal fish would generally gain precision by increasingly including spatially based assessments

  6. Responses of coastal ecosystems to environmental variability in emerging countries from the Americas

    Science.gov (United States)

    Muniz, Pablo; Calliari, Danilo; Giménez, Luis; Defeo, Omar

    2015-12-01

    Coastal ecosystems supply critical ecological services and benefits to human society (Barbier et al., 2011). Nearly 38% of the global monetary value of annual ecosystem services arises from estuaries, seagrass and algal beds, coral reefs and shelf ecosystems (Costanza et al., 1997). However, these ecosystems are being increasingly affected by multiple drivers acting simultaneously at several spatial and temporal scales (Lotze et al., 2006; Hoegh-Guldberg and Bruno, 2010). Climate change (temperature increase, sea level rise, ocean acidification), human activities (e.g. land use/cover change, pollution, overexploitation, translocation of species), and extreme natural events (storms, floods, droughts) are the most important drivers degrading the resilience of coastal systems. Such factors operate on individual level processes, leading organisms away from their niches (Steinberg, 2013) or modifying rates and phenology (Giménez, 2011; Mackas et al., 2012, Deutsch et al., 2015). All of these influence ecosystem level processes, causing changes in species composition, diversity losses and deterioration of ecosystem functions (Worm et al., 2006; Defeo et al., 2009; Doney et al., 2011; Dornelas et al., 2014). The rate of change in habitats, species distributions and whole ecosystems has accelerated over the past decades as shown, for example, in the increase in the frequency of events of coastal hypoxia (Diaz and Rosenberg, 2008,Vaquer-Sunyer and Duarte, 2008), extensive translocation of species by global shipping (Seebens et al., 2013), and in ecosystem regime shifts (Möllmann et al., 2015 and references therein). Some coastal areas have been transformed into novel ecosystems with physical and biological characteristics outside their natural range of variability (Cloern et al., 2015) while others are likely to become sink areas, limiting the migration of marine species away from warming habitats (Burrows et al., 2014).

  7. Environmental responses of the Northeast Antarctic Peninsula to the Holocene climate variability

    Science.gov (United States)

    Barbara, Loïc.; Crosta, Xavier; Leventer, Amy; Schmidt, Sabine; Etourneau, Johan; Domack, Eugene; Massé, Guillaume

    2016-01-01

    In this study, we present a unique high-resolution Holocene record of oceanographic and climatic change based on analyses of diatom assemblages combined with biomarker data from a sediment core collected from the Vega Drift, eastern Antarctic Peninsula (EAP). These data add to the climate framework already established by high-resolution marine sedimentary records from the Palmer Deep, western Antarctic Peninsula (WAP). Heavy sea ice conditions and reduced primary productivity were observed prior to 7.4 ka B.P. in relation with the proximity of the glacial ice melt and calving. Subsequent Holocene oceanographic conditions were controlled by the interactions between the Westerlies-Antarctic Circumpolar Current (ACC)-Weddell Gyre dynamics. A warm period characterized by short seasonal sea ice duration associated with a southern shift of both ACC and Westerlies field persisted until 5 ka B.P. This warm episode was then followed by climate deterioration during the middle-to-late Holocene (5 to 1.9 ka B.P.) with a gradual increase in annual sea ice duration triggered by the expansion of the Weddell Gyre and a strong oceanic connection from the EAP to the WAP. Increase of benthic diatom species during this period was indicative of more summer/autumn storms, which was consistent with changes in synoptic atmospheric circulation and the establishment of low- to high-latitude teleconnections. Finally, the multicentennial scale variability of the Weddell Gyre intensity and storm frequency during the late Holocene appeared to be associated with the increased El Niño-Southern Oscillation frequency.

  8. Gastrointestinal and renal responses to variable water intake in whitebellied sunbirds and New Holland honeyeaters.

    Science.gov (United States)

    Purchase, Cromwell; Napier, Kathryn R; Nicolson, Susan W; McWhorter, Todd J; Fleming, Patricia A

    2013-05-01

    Nectarivores face a constant challenge in terms of water balance, experiencing water loading or dehydration when switching between food plants or between feeding and fasting. To understand how whitebellied sunbirds and New Holland honeyeaters meet the challenges of varying preformed water load, we used the elimination of intramuscular-injected [(14)C]-l-glucose and (3)H2O to quantify intestinal and renal water handling on diets varying in sugar concentration. Both sunbirds and honeyeaters showed significant modulation of intestinal water absorption, allowing excess water to be shunted through the intestine when on dilute diets. Despite reducing their fractional water absorption, both species showed linear increases in water flux and fractional body water turnover as water intake increased (both afternoon and morning), suggesting that the modulation of fractional water absorption was not sufficient to completely offset dietary water loads. In both species, glomerular filtration rate was independent of water gain (but was higher for the afternoon), as was renal fractional water reabsorption (measured in the afternoon). During the natural overnight fast, both sunbirds and honeyeaters arrested whole kidney function. Evaporative water loss in sunbirds was variable but correlated with water gain. Both sunbirds and honeyeaters appear to modulate intestinal water absorption as an important component of water regulation to help deal with massive preformed water loads. Shutting down glomerular filtration rate during the overnight fast is another way of saving energy for osmoregulatory function. Birds maintain osmotic balance on diets varying markedly in preformed water load by varying both intestinal water absorption and excretion through the intestine and kidneys.

  9. A constrained variable projection reconstruction method for photoacoustic computed tomography without accurate knowledge of transducer responses

    CERN Document Server

    Sheng, Qiwei; Matthews, Thomas P; Xia, Jun; Zhu, Liren; Wang, Lihong V; Anastasio, Mark A

    2015-01-01

    Photoacoustic computed tomography (PACT) is an emerging computed imaging modality that exploits optical contrast and ultrasonic detection principles to form images of the absorbed optical energy density within tissue. When the imaging system employs conventional piezoelectric ultrasonic transducers, the ideal photoacoustic (PA) signals are degraded by the transducers' acousto-electric impulse responses (EIRs) during the measurement process. If unaccounted for, this can degrade the accuracy of the reconstructed image. In principle, the effect of the EIRs on the measured PA signals can be ameliorated via deconvolution; images can be reconstructed subsequently by application of a reconstruction method that assumes an idealized EIR. Alternatively, the effect of the EIR can be incorporated into an imaging model and implicitly compensated for during reconstruction. In either case, the efficacy of the correction can be limited by errors in the assumed EIRs. In this work, a joint optimization approach to PACT image r...

  10. Comparison of arterial pressure and plethysmographic waveform-based dynamic preload variables in assessing fluid responsiveness and dynamic arterial tone in patients undergoing major hepatic resection

    NARCIS (Netherlands)

    Vos, J. J.; Kalmar, A. F.; Struys, M. M. R. F.; Wietasch, J. K. G.; Hendriks, H. G. D.; Scheeren, T. W. L.

    2013-01-01

    Dynamic preload variables to predict fluid responsiveness are based either on the arterial pressure waveform (APW) or on the plethysmographic waveform (PW). We compared the ability of APW-based variations in stroke volume (SVV) and pulse pressure (PPV) and of PW-based plethysmographic variability in

  11. Application of response surface methodology to assess the combined effect of operating variables on high-pressure coal gasification for H2-rich gas production

    OpenAIRE

    Fermoso Domínguez, Javier; Gil Matellanes, María Victoria; Arias Rozada, Borja; González Plaza, Marta; Pevida García, Covadonga; Pis Martínez, José Juan; Rubiera González, Fernando

    2010-01-01

    Coal gasification was performed by means of a high-pressure fixed bed gasifier fitted with a solids feeding system in continuous mode, using oxygen and steam as gasifying agents. The main aim of the paper was to assess the combined effects of the operating variables (temperature, oxygen and steam concentrations) on high-pressure coal gasification. To this end a face centered central composite design (FCCCD) based on response surface methodology (RSM) was used. The response variables studied w...

  12. Intra-specific variability in the response of maize to arsenic exposure.

    Science.gov (United States)

    Requejo, Raquel; Tena, Manuel

    2014-09-01

    The response of maize (Zea mays L.) to inorganic arsenic exposure was studied, at the seedling stage under hydroponic conditions, preliminarily in sixteen lines (fourteen hybrids and two inbred lines) and then, more deeply, in six of these lines, selected by showing contrasting differences in their sensitivity to the metalloid. The results indicated that (i) maize is rather tolerant to arsenic toxicity, (ii) arsenite is more phytotoxic than arsenate, (iii) roots are less sensitive than shoots to the metalloid, (iv) a great accumulation of non-protein thiols (probably phytochelatins), without substantial effect on the glutathione content, is produced in roots but not in shoots of arsenic-exposed plants and (v) maize is able to accumulate high levels of arsenic in roots with very low translocation to shoots. The study, thus, suggests that maize, for its very low rate of acropetal transport of arsenic from roots to shoots, may be a safe crop in relation to the risk of entry of metalloid in the food chain and, for being an important bioenergy crop capable of expressing high levels of arsenic tolerance and accumulation in roots, may represent an interesting opportunity for the exploitation of agricultural useless arsenic contaminated lands.

  13. WEDM process variables investigation for HSLA by response surface methodology and genetic algorithm

    Directory of Open Access Journals (Sweden)

    Neeraj Sharma

    2015-06-01

    Full Text Available Wire electric discharge machining (WEDM is a thermo-electric spark erosion non-traditional type manufacturing process. The applications of WEDM have been found in aerospace and die manufacturing industries, where precise dimensions were the prime objective. This process is applied in case of processing difficult to machine material. Brass wire is used as an electrode and High strength low alloy (HSLA steel as a work-piece during experimentation. The present research deals with the effect of process parameters on the overcut while machining the HSLA steel on WEDM. The mathematical model has been developed with the help of Response Surface Methodology (RSM. Further this model is processed with help of Genetic Algorithm (GA to find out the optimum machining parameters. The percentage error between the predicted and experimental values lies in the range of ±10%, which indicates that the developed model can be utilized to predict the overcut values. The experimental plan was executed according to central composite design. The optimal setting of process parameters is pulse on-time-117 μs; pulse off-time-50 μs; spark gap voltage-49 V; peak current-180 A and wire tension-6 g; for minimum overcut, whereas at the optimal setting overcut is 9.9922 μm.

  14. Computational Study of Plasma Response to a Variable Electric Multipole Configuration

    Science.gov (United States)

    Hicks, Nathaniel

    2016-10-01

    A computational study is presented of the behavior of a low temperature, quasi-neutral plasma in a three-dimensional, time-varying electric multipole field. A 3-D particle- in-cell (PIC) plasma code is used to simulate the process. The simulations study the effect of the plasma species' mass difference on the plasma response, with the multipole field frequency being chosen, for example, to interact strongly with light particles but negligibly with heavy ones. The effect of focusing the light species to the center of the multipole structure is examined, with space charge neutralized by the presence of the heavy species. The dependence of plasma density on driving field parameters and geometry (order of multipole, shape of equipotential surfaces) is studied, as well as the behavior of the plasma near gyroresonance in the presence of a background magnetic field. The formation and dependences of the RF plasma sheath are studied, as the sheath responds to variation of the plasma and external field characteristics. The results of the computer modeling study are to inform an initial experimental design and study of the same effects. Supported by NSF/DOE Partnership in Basic Plasma Physics and Engineering Award PHY-1619615.

  15. Flexible designs for phase II comparative clinical trials involving two response variables.

    Science.gov (United States)

    Bersimis, S; Sachlas, A; Papaioannou, T

    2015-01-30

    The aim of phase II clinical trials is to determine whether an experimental treatment is sufficiently promising and safe to justify further testing. The need for reduced sample size arises naturally in phase II clinical trials owing to both technical and ethical reasons, motivating a significant part of research in the field during recent years, while another significant part of the research effort is aimed at more complex therapeutic schemes that demand the consideration of multiple endpoints to make decisions. In this paper, our attention is restricted to phase II clinical trials in which two treatments are compared with respect to two dependent dichotomous responses proposing some flexible designs. These designs permit the researcher to terminate the clinical trial when high rates of favorable or unfavorable outcomes are observed early enough requiring in this way a small number of patients. From the mathematical point of view, the proposed designs are defined on bivariate sequences of multi-state trials, and the corresponding stopping rules are based on various distributions related to the waiting time until a certain number of events appear in these sequences. The exact distributions of interest, under a unified framework, are studied using the Markov chain embedding technique, which appears to be very useful in clinical trials for the sample size determination. Tables of expected sample size and power are presented. The numerical illustration showed a very good performance for these new designs.

  16. Floods in Colombia (2009-2011): rethinking our response to climatic variability

    Science.gov (United States)

    Canon Barriga, J. E.

    2011-12-01

    The alternating El Niño-La Niña events of 2009-2011 are clear examples of the extreme weather variability that we can expect from climate-change conditions around the world. This presentation will discuss the impact that such events have had already in Colombia and will suggest ways to deal with similar events in the future. In less than a year the country passed from a dry El Niño (in which the system of reservoirs for water supply and hydropower dropped to critical levels) to a wet La Niña (in which a heavy, sustained rainy period caused landslides and major floods in most of the floodplains and main cities and put the reservoirs to work at their maximum capacity). As a result of the rains, several levees, bridges and roads across the country failed or collapsed, prompting the government to declare a state of emergency and to propose an ambitious plan for the reconstruction of the country's infrastructure in the following years. Many of the effects of these floods, which occur seasonally at lower scales, were magnified by the increasing human occupation of wetlands and floodplains due to different economic interests and by decades of transformation of forested areas in the mountains for pastures and cattle-growing. We drawn several lessons from these alternate occurrence of weather extremes: 1) reservoirs, for instance, may not be resilient to the occurrence of a single period of severe dryness and have a limited capacity to control floods during seasons of heavy rain; 2) alternating weather extremes may leave governments with limited time to respond within the regular seasonal cycle and solutions may be delayed and unreliable (as the PDO enters in a negative phase in the coming years, La Niña events and wetter than normal conditions in the country are likely to become more frequent, extending the rainy season cycle); 3) several years of deforestation in the cordillera have increased erosive processes and sediment loads making the rivers more difficult to

  17. Hydrological Responses of Andean Lakes and Tropical Floodplains to Climate Variability and Human Intervention: an Integrative Modelling Framework

    Science.gov (United States)

    Hoyos, I. C.; González Morales, C.; Serna López, J. P.; Duque, C. L.; Canon Barriga, J. E.; Dominguez, F.

    2013-12-01

    Andean water bodies in tropical regions are significantly influenced by fluctuations associated with climatic and anthropogenic drivers, which implies long term changes in mountain snow peaks, land covers and ecosystems, among others. Our work aims at providing an integrative framework to realistically assess the possible future of natural water bodies with different degrees of human intervention. We are studying in particular the evolution of three water bodies in Colombia: two Andean lakes and a floodplain wetland. These natural reservoirs represent the accumulated effect of hydrological processes in their respective basins, which exhibit different patterns of climate variability and distinct human intervention and environmental histories. Modelling the hydrological responses of these local water bodies to climate variability and human intervention require an understanding of the strong linkage between geophysical and social factors. From the geophysical perspective, the challenge is how to downscale global climate projections in the local context: complex orography and relative lack of data. To overcome this challenge we combine the correlational and physically based analysis of several sources of spatially distributed biophysical and meteorological information to accurately determine aspects such as moisture sources and sinks and past, present and future local precipitation and temperature regimes. From the social perspective, the challenge is how to adequately represent and incorporate into the models the likely response of social agents whose water-related interests are diverse and usually conflictive. To deal with the complexity of these systems we develop interaction matrices, which are useful tools to holistically discuss and represent each environment as a complex system. Our goal is to assess partially the uncertainties of the hydrological balances in these intervened water bodies we establish climate/social scenarios, using hybrid models that combine

  18. UV photolysis for accelerating pyridine biodegradation.

    Science.gov (United States)

    Zhang, Yongming; Chang, Ling; Yan, Ning; Tang, Yingxia; Liu, Rui; Rittmann, Bruce E

    2014-01-01

    Pyridine, a nitrogen-containing heterocyclic compound, is slowly biodegradable, and coupling biodegradation with UV photolysis is a potential means to accelerate its biotransformation and mineralization. The initial steps of pyridine biodegradation involve mono-oxygenation reactions that have molecular oxygen and an intracellular electron carrier as cosubstrates. We employed an internal circulation baffled biofilm reactor for pyridine biodegradation following three protocols: direct biodegradation (B), biodegradation after photolysis (P+B), and biodegradation with succinic acid added (B+S). Succinic acid was the main UV-photolysis product from pyridine, and its catabolic oxidation generates internal electron carriers that may accelerate the initial steps of pyridine biodegradation. Compared with direct biodegradation of pyridine (B), the removal rate for the same concentration of photolyzed pyridine (P+B) was higher by 15 to 43%, depending on the initial pyridine concentrations (increasing through the range of 130 to 310 mg/L). Adding succinic acid alone (B+S) gave results similar to P+B, which supports that succinic acid was the main agent for accelerating the pyridine biodegradation rate. In addition, protocols P+B and B+S were similar in terms of increasing pyridine mineralization over 10 h: 84% and 87%, respectively, which were higher than with protocol B (72%). The positive impact of succinic acid-whether added directly or produced via UV photolysis-confirms that its catabolism, which produced intracellular electron carriers, accelerated the initial steps of pyridine biotransformation.

  19. Aerobic biodegradation of a nonylphenol polyethoxylate and toxicity of the biodegradation metabolites.

    Science.gov (United States)

    Jurado, Encarnación; Fernández-Serrano, Mercedes; Núñez-Olea, Josefa; Lechuga, Manuela

    2009-09-01

    In this paper a study was made of the biodegradation of a non-ionic surfactant, a nonylphenol polyethoxylate, in biodegradability tests by monitoring the residual surfactant matter. The influence of the concentration on the extent of primary biodegradation, the toxicity of biodegradation metabolites, and the kinetics of degradation were also determined. The primary biodegradation was studied at different initial concentrations: 5, 25 and 50 mg/L, (at sub-and supra-critical micelle concentration). The NPEO used in this study can be considered biodegradable since the primary biodegradation had already taken place (a biodegradation greater than 80% was found for the different initial concentration tested). The initial concentration affected the shape of the resulting curve, the mean biodegradation rate and the percentage of biodegradation reached (99% in less than 8 days at 5 mg/L, 98% in less than 13 days at 25 mg/L and 95% in 14 days at 50 mg/L). The kinetic model of Quiroga and Sales (1991) was applied to predict the biodegradation of the NPEO. The toxicity value was measured as EC(20) and EC(50). In addition, during the biodegradation process of the surfactant a toxicity analysis was made of the evolution of metabolites generated, confirming that the subproducts of the biodegradation process were more toxic than the original.

  20. COMMUNICATION: On variability and use of rat primary motor cortex responses in behavioral task discrimination

    Science.gov (United States)

    Jensen, Winnie; Rousche, Patrick J.

    2006-03-01

    The success of a cortical motor neuroprosthetic system will rely on the system's ability to effectively execute complex motor tasks in a changing environment. Invasive, intra-cortical electrodes have been successfully used to predict joint movement and grip force of a robotic arm/hand with a non-human primate (Chapin J K, Moxon K A, Markowitz R S and Nicolelis M A L 1999 Real-time control of a robotic arm using simultaneously recorded neurons in the motor cortex Nat. Neurosci. 2 664-70). It is well known that cortical encoding occurs with a high degree of cortical plasticity and depends on both the functional and behavioral context. Questions on the expected robustness of future motor prosthesis systems therefore still remain. The objective of the present work was to study the effect of minor changes in functional movement strategies on the M1 encoding. We compared the M1 encoding in freely moving, non-constrained animals that performed two similar behavioral tasks with the same end-goal, and investigated if these behavioral tasks could be discriminated based on the M1 recordings. The rats depressed a response paddle either with a set of restrictive bars ('WB') or without the bars ('WOB') placed in front of the paddle. The WB task required changes in the motor strategy to complete the paddle press and resulted in highly stereotyped movements, whereas in the WOB task the movement strategy was not restricted. Neural population activity was recorded from 16-channel micro-wire arrays and data up to 200 ms before a paddle hit were analyzed off-line. The analysis showed a significant neural firing difference between the two similar WB and WOB tasks, and using principal component analysis it was possible to distinguish between the two tasks with a best classification at 76.6%. While the results are dependent upon a small, randomly sampled neural population, they indicate that information about similar behavioral tasks may be extracted from M1 based on relatively few

  1. [Stabilization of operant responses during a program of variable interval reinforcement as a preliminary investigation of sensory thresholds using conditioned suppression in the cat].

    Science.gov (United States)

    Fregnac, Y; Gary-Bobo, E; Imbert, M

    1977-09-19

    Cats were trained to press a key during a variable interval schedule of reinforcement with a limited hold contingency. The main modifications of the response rate were observed when the subject missed one reinforcement or obtained more than one reinforcement during the limited hold. The existence of a zone of lesser variability in the mean response rate is shown to be linked to the occurrence of the last reinforcement. This result suggests an original methodological contingency concerning the use of conditioned suppression in psychophysics. The schedule of sensory stimulation should be established for each subject during that period of lesser variability between two reinforcements.

  2. Aerobic biodegradation of a mixture of monosubstituted phenols in a sequencing batch reactor

    Energy Technology Data Exchange (ETDEWEB)

    Fernández, Isaac; Suárez-Ojeda, María Eugenia; Pérez, Julio; Carrera, Julián, E-mail: julian.carrera@uab.es

    2013-09-15

    Highlights: • Aerobic biodegradation of a mixture of p-nitrophenol and o-cresol is feasible. • Simultaneous biodegradation of p-nitrophenol and o-cresol was achieved at long-term. • o-Chlorophenol caused complete failure of the sequencing batch reactor. • Biomass had good settling properties although no mature granules were obtained. • p-Nitrophenol is believed to be responsible for granulation failure. -- Abstract: A sequencing batch reactor (SBR) was inoculated with p-nitrophenol-degrading activated sludge to biodegrade a mixture of monosubstituted phenols: p-nitrophenol (PNP), PNP and o-cresol; and PNP, o-cresol and o-chlorophenol. Settling times were progressively decreased to promote biomass granulation. PNP was completely biodegraded. The PNP and o-cresol mixture was also biodegraded although some transitory accumulation of intermediates occurred (mainly hydroquinone and catechol). o-Chlorophenol was not biodegraded and resulted in inhibition of o-cresol and PNP biodegradation and complete failure of the SBR within a few days. The biomass had very good settling properties when a settling time of 1 min was applied: sludge volume index (SVI{sub 5}) below 50 mL g{sup −1}, SVI{sub 5}/SVI{sub 30} ratio of 1 and average particle size of 200 μm.

  3. Kinetics and thermodynamics of biodegradation of hydrolyzed polyacrylamide under anaerobic and aerobic conditions.

    Science.gov (United States)

    Zhao, Lanmei; Bao, Mutai; Yan, Miao; Lu, Jinren

    2016-09-01

    Kinetics and thermodynamics of hydrolyzed polyacrylamide (HPAM) biodegradation in anaerobic and aerobic activated sludge biochemical treatment systems were explored to determine the maximum rate and feasibility of HPAM biodegradation. The optimal nutrient proportions for HPAM biodegradation were determined to be 0.08g·L(-1) C6H12O6, 1.00g·L(-1) NH4Cl, 0.36g·L(-1) NaH2PO4 and 3.00g·L(-1) K2HPO4 using response surface methodology (RSM). Based on the kinetics, the maximum HPAM biodegradation rates were 16.43385mg·L(-1)·d(-1) and 2.463mg·L(-1)·d(-1) in aerobic and anaerobic conditions, respectively. The activation energy (Ea) of the aerobic biodegradation was 48.9897kJ·mol(-1). Entropy changes (ΔS) of biochemical treatment system decreased from 216.21J·K(-1) to 2.39J·K(-1). Thermodynamic windows of opportunity for HPAM biodegradation were drawn. And it demonstrated HPAM was biodegraded into acetic acid and CO2 under laboratory conditions. Growth-process equations for functional bacteria anaerobically grown on polyacrylic acid were constructed and it confirmed electron equivalence between substrate and product.

  4. Geological and Geophysical Models Underneath Bucharest City Responsible for the Variability of Seismic Site Effects

    Science.gov (United States)

    Bala, A.; Aldea, A.; Balan, S. F.; Arion, C.

    2012-04-01

    assembled which contains: Vp and Vs values for each sedimentary layer, density and geologic characteristics of each layer, which are the basic data for equivalent linear modelling of the site; other geotechnical parameters measured in the laboratory on the rock samples will permit the nonlinear modelling of the site. Using the program SHAKE2000 and EERA we compute spectral acceleration functions at specific depths and transfer functions for the 1D models obtained from the in situ measurements. The acceleration response spectra correspond to the wave amplifications due to the package of sedimentary layers from 50 m depth (maximum depth) up to the surface, that are expected for a moderate real earthquake motion incident at the bottom of each 1D model. Because of the lack of outcropping bedrock in the Bucharest area, a seismic signal recorded in a borehole (PRI - 50 m depth; TEI- 78 m depth; INC - 140 m depth) at a moderate earthquake (Mw= 6), is used as input for the entire study area. 1D models obtained were tested in order to strengthen the importance of various input parameters in the obtained results. The results of the equivalent linear modeling with SHAKE2000 program for the 10 boreholes are presented and compared as graphs of spectral acceleration. The maximum values of the spectral accelerations occur around the 3 main the periods: T1 = 0.13 s; T2 = 0.2 s; T3 = 0.55 s. The highest values occured at the period T2 = 0.2 s, and they are between 0.22 g and 0.48 g. If we consider a comparison of the values at surface, they are between 0.22 g at Romanian Shooting Fed. (northern part of Bucharest) and 0.48 g (Ecologic Univ. in the central part of Bucharest).

  5. Discontinuous aerobic biodegradation of dairy wastewater: influence of operation conditions; Depuracion aerobia de vertidos lacteos en regimen discontinuo: influencia de las condiciones de operacion

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez Mateos, P.; Romero guzman, F.; Pereda Marin, J. [Departamento Ingenieria Quimica, Facultad de Quimica, Universidad de Sevilla, Sevilla (Spain)

    1995-11-01

    In this work, the effect of different parameters on the aerobic biodegradation of the dairy wastewater has been studied. The variables have been: temperature, initial pH value, light, temperature of the incubation and conditions of adaptability of the inoculum and initial organic load. a kinetic equation that fit of the best to this biodegradation process is studied. 8 refs.

  6. Variability in prefrontal hemodynamic response during exposure to repeated self-selected music excerpts, a near-infrared spectroscopy study.

    Directory of Open Access Journals (Sweden)

    Saba Moghimi

    Full Text Available Music-induced brain activity modulations in areas involved in emotion regulation may be useful in achieving therapeutic outcomes. Clinical applications of music may involve prolonged or repeated exposures to music. However, the variability of the observed brain activity patterns in repeated exposures to music is not well understood. We hypothesized that multiple exposures to the same music would elicit more consistent activity patterns than exposure to different music. In this study, the temporal and spatial variability of cerebral prefrontal hemodynamic response was investigated across multiple exposures to self-selected musical excerpts in 10 healthy adults. The hemodynamic changes were measured using prefrontal cortex near infrared spectroscopy and represented by instantaneous phase values. Based on spatial and temporal characteristics of these observed hemodynamic changes, we defined a consistency index to represent variability across these domains. The consistency index across repeated exposures to the same piece of music was compared to the consistency index corresponding to prefrontal activity from randomly matched non-identical musical excerpts. Consistency indexes were significantly different for identical versus non-identical musical excerpts when comparing a subset of repetitions. When all four exposures were compared, no significant difference was observed between the consistency indexes of randomly matched non-identical musical excerpts and the consistency index corresponding to repetitions of the same musical excerpts. This observation suggests the existence of only partial consistency between repeated exposures to the same musical excerpt, which may stem from the role of the prefrontal cortex in regulating other cognitive and emotional processes.

  7. Variability of North Sea pH and CO2 in response to North Atlantic Oscillation forcing

    Science.gov (United States)

    Salt, Lesley A.; Thomas, Helmuth; Prowe, A. E. Friederike; Borges, Alberto V.; Bozec, Yann; Baar, Hein J. W.

    2013-12-01

    biological activity causes a distinct seasonality of surface water pH in the North Sea, which is a strong sink for atmospheric CO2 via an effective shelf pump. The intimate connection between the North Sea and the North Atlantic Ocean suggests that the variability of the CO2 system of the North Atlantic Ocean may, in part, be responsible for the observed variability of pH and CO2 in the North Sea. In this work, we demonstrate the role of the North Atlantic Oscillation (NAO), the dominant climate mode for the North Atlantic, in governing this variability. Based on three extensive observational records covering the relevant levels of the NAO index, we provide evidence that the North Sea pH and CO2 system strongly responds to external and internal expressions of the NAO. Under positive NAO, the higher rates of inflow of water from the North Atlantic Ocean and the Baltic outflow lead to a strengthened north-south biogeochemical divide. The limited mixing between the north and south leads to a steeper gradient in pH and partial pressure of CO2 (pCO2) between the two regions in the productive period. This is exacerbated further when coinciding with higher sea surface temperature, which concentrates the net community production in the north through shallower stratification. These effects can be obscured by changing properties of the constituent North Sea water masses, which are also influenced by NAO. Our results highlight the importance of examining interannual trends in the North Sea CO2 system with consideration of the NAO state.

  8. Tree ring variability and climate response of Abies spectabilis along an elevation gradient in Mustang, Nepal

    DEFF Research Database (Denmark)

    Kharal, D.K.; Meilby, Henrik; Rayamajhi, S.;

    2014-01-01

    In mountainous areas including the Himalayas, tree lines are expected to advance to higher altitudes due to global climate change affecting the distribution and growth of plant species. This study aimed at identifying the tree ring variability of Abies spectabilis (D. Don) and its response...... to the climate along an elevation gradient in the high Himalayas of central Nepal. Tree core samples were collected from four sites in Mustang district. All sites were located in the same valley and exposed to similar weather conditions. Out of 232 samples collected from the sites, Titi lower (2700 m), Titi......-elevation sites the correlation between pre-monsoon precipitation and tree growth was positive, and for the month of May this was statistically significant (ptemperature (March-June) was negatively correlated with precipitation and with tree growth at all sites, and at the upper elevation...

  9. Dispersibility-Dependent Biodegradation of Graphene Oxide by Myeloperoxidase.

    Science.gov (United States)

    Kurapati, Rajendra; Russier, Julie; Squillaci, Marco A; Treossi, Emanuele; Ménard-Moyon, Cécilia; Del Rio-Castillo, Antonio Esaú; Vazquez, Ester; Samorì, Paolo; Palermo, Vincenzo; Bianco, Alberto

    2015-08-26

    Understanding human health risk associated with the rapidly emerging graphene-based nanomaterials represents a great challenge because of the diversity of applications and the wide range of possible ways of exposure to this type of materials. Herein, the biodegradation of graphene oxide (GO) sheets is reported by using myeloperoxidase (hMPO) derived from human neutrophils in the presence of a low concentration of hydrogen peroxide. The degradation capability of the enzyme on three different GO samples containing different degree of oxidation on their graphenic lattice, leading to a variable dispersibility in aqueous media is compared. hMPO fails in degrading the most aggregated GO, but succeeds to completely metabolize highly dispersed GO samples. The spectroscopy and microscopy analyses provide unambiguous evidence for the key roles played by hydrophilicity, negative surface charge, and colloidal stability of the aqueous GO in their biodegradation by hMPO catalysis.

  10. Diverse Responses of Remotely Sensed Grassland Phenology to Interannual Climate Variability over Frozen Ground Regions in Mongolia

    Directory of Open Access Journals (Sweden)

    Zhigang Sun

    2014-12-01

    Full Text Available Frozen ground may regulate the phenological shifts of dry and cold grasslands at the southern edge of the Eurasian cryosphere. In this study, an investigation based on the MODIS Collection 5 phenology product and climatic data collected from 2001 to 2009 reveals the diverse responses of grassland phenology to interannual climate variability over various frozen ground regions in Mongolia. Compared with middle and southern typical steppe and desert steppe, the spring (start of season; SOS and autumn (end of season; EOS phenological events of northern forest steppe with lower air temperature tend to be earlier and later, respectively. Both the SOS and EOS are less sensitive to climate variability in permafrost regions than in other regions, whereas the SOS of typical steppe is more sensitive to both air temperature and precipitation over sporadic permafrost and seasonal frozen ground regions. Over various frozen ground regions in Mongolia; the SOS is mainly dominated by the prior autumn precipitation, and frozen ground plays a vital role in storing the precipitation of the previous autumn for the subsequent grass green-up. The EOS is mainly dominated by autumn air temperature. These findings could help to improve phenological models of grasslands in extremely dry and cold regions.

  11. Hourly Fluctuations in Labile Soil Phosphorus in Response to Climate Variability in a Wet Tropical Forest, La Selva, Costa Rica

    Science.gov (United States)

    Vandecar, K. L.; Lawrence, D. C.; Das, R.; Clark, D. A.; Oberbauer, S. F.; Schwendenmann, L.

    2007-05-01

    Tropical rain forests are one of the most productive ecosystems in the world and play a significant role in the global carbon budget. Changes in phosphorus cycling dynamics as a result of on-going climate change have the potential to limit productivity in this ecosystem. Our objective was to determine hourly patterns in labile soil phosphorus throughout the day and explore possible mechanisms driving these patterns. We conducted an in situ experiment on soils from a wet tropical forest at La Selva Biological Station located in N.E. Costa Rica. A variety of climatic and biotic variables including temperature, precipitation, PAR, soil temperature, soil moisture and soil respiration were measured in order to determine their effect on labile phosphorus. Our results indicate that labile phosphorus does vary significantly throughout the day in response to a combination of climatic variables. An understanding of the mechanisms driving phosphorus availability at fine temporal scales can provide a valuable indicator of long term trends in phosphorus cycling dynamics.

  12. Response of the everglades ridge and slough landscape to climate variability and 20th-century water management

    Science.gov (United States)

    Bernhardt, C.E.; Willard, D.A.

    2009-01-01

    The ridge and slough landscape of the Florida Everglades consists of a mosaic of linear sawgrass ridges separated by deeper-water sloughs with tree islands interspersed throughout the landscape. We used pollen assemblages from transects of sediment cores spanning sawgrass ridges, sloughs, and ridge-slough transition zones to determine the timing of ridge and slough formation and to evaluate the response of components of the ridge and slough landscape to climate variability and 20th-century water management. These pollen data indicate that sawgrass ridges and sloughs have been vegetationally distinct from one another since initiation of the Everglades wetland in mid-Holocene time. Although the position and community composition of sloughs have remained relatively stable throughout their history, modern sawgrass ridges formed on sites that originally were occupied by marshes. Ridge formation and maturation were initiated during intervals of drier climate (the Medieval Warm Period and the Little Ice Age) when the mean position of the Intertropical Convergence Zone shifted southward. During these drier intervals, marsh taxa were more common in sloughs, but they quickly receded when precipitation increased. Comparison with regional climate records suggests that slough vegetation is strongly influenced by North Atlantic Oscillation variability, even under 20th-century water management practices. ?? 2009 by the Ecological Society of America.

  13. The UK Food Standards Agency draft report on variability and uncertainty in toxicology: a response by FRAME.

    Science.gov (United States)

    Bhogal, Nirmala; Combes, Robert

    2006-10-01

    At the request of the Food Standards Agency, the Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment (COT) established a Working Group on Variation and Uncertainty in Toxicology (WG VUT). In April 2006, the WG VUT produced a draft report for public consultation. FRAME made a submission in response to this consultation in July 2006. We commend the WG VUT for its comprehensive account of many of the problems associated with risk assessment, and for making recommendations about the problems that need to be addressed. We were particularly encouraged by the WG VUTs recognition of the need for guidelines on how toxicological studies should be conducted and data analysed. However, we believe that the report has not achieved all of its objectives. It does not adequately consider how modern technologies, experimental design, statistical analysis and species extrapolation can be used in practice to address variability and uncertainty. There is a disproportionate focus on the sources of variability and uncertainty in human data, with relatively little consideration of how variation and uncertainty due to animal tests can be addressed. Furthermore, it is clear that, until the advantages and limitations of all toxicological methods are fully appraised and testing strategies and guidelines are agreed, the scope for improving the existing approaches to risk assessment will be severely limited. Hence, the use of alternative methods for hazard identification and characterisation merit more consideration than they were given in the draft report.

  14. Response Surfaces for Key Controlled Variables in a Hybrid Solid Oxide Fuel Cell/Gas Turbine System

    Energy Technology Data Exchange (ETDEWEB)

    Rosen, William G; Banta, Larry; Gorrell, Megan; Restrepo, Bernardo; Tucker, David

    2012-07-01

    Hybrid generation systems have been extensively modeled as a first step toward the development of automatic controls for the system. In most cases, it is impossible to validate mathematical models against real hardware because only a handful of hardware systems exist in the world. Data taken from the existing hardware has demonstrated significant nonlinearity, complex coupling between controlled variables, and sometimes non-intuitive behavior. This work exploits the capability of the HyPer hardware test bed at the National Energy Technology Laboratory (NETL) to generate data from a real recuperated gas turbine coupled with hardware simulations of a fuel cell cathode and appropriate ancillary equipment. Prior work has characterized the system only over a limited range of its operating envelope, due to the inability to manipulate multiple control inputs simultaneously. The work presented here fills the gaps using data from a 34 factorial experiment to generate quasi-continuous response surfaces describing the operating state space of the HyPer system. Polynomial correlation functions have been fitted to the data with excellent agreement. Relationships between the control inputs and critical state variables such as cathode mass flow, cathode temperature, turbine inlet and exhaust temperatures and other key system parameters are presented.

  15. Assessment of penetration potential of pH responsive double walled biodegradable nanogels coated with eucalyptus oil for the controlled delivery of 5-fluorouracil: In vitro and ex vivo studies.

    Science.gov (United States)

    Sahu, Prashant; Kashaw, Sushil K; Jain, Sanyog; Sau, Samaresh; Iyer, Arun K

    2017-03-17

    Penetration enhancers coated biodegradable polymeric nanogels loaded with cytotoxic drugs applied via the topical route, can be a promising strategy for improving the chemotherapeutic efficiency of skin cancers. The major objective of proposed research was to investigate the in vitro and ex vivo chemotherapeutic potential of double walled PLGA-chitosan biodegradable nanogel entrapped with 5-fluororuacil (5-FU) coated with eucalyptus oil, topically applied onto the skin. 5-FU was first entrapped in PLGA core by solvent evaporation technique followed by coating with cationic chitosan for ionic interaction with anionic skin cancer cell membrane. A surface coating of eucalyptus oil (1%) was employed to improve the penetration efficacy of the nanogel into stratum corneum. The surface modified biodegradable double walled nanogel was characterized for particle size, charge and thermal properties followed by pH dependent in vitro analysis. Human keratinocyte (HaCaT) cell line was employed for the bio- and cyto-compatibility testing prior to the hemolysis assay and coagulation assessment. A porcine skin ex vivo screening was performed for assessing the penetration potential of the nanogels. DLS and TEM revealed a particle size of 170nm for the double walled nanogels. The nanogels also exhibited high thermal stability as analyzed by thermogravimetry (TG) and differential thermal analysis (DTA). The drug entrapment efficacy was about ~45%. The drug release showed sustained release pattern noted up to 24h. The low hemolysis of 3.31% with short prothrombin time (PT) and activated partial thromboplastin time (APTT) of 13.5 and 33s respectively, revealed high biocompatibility of the nanogels. The cellular uptake and localization was assessed by confocal microscopy. The cytotoxicity (MTT assay) on HaCaT cell line demonstrated high cytocompatibilty of the nanogels. An ex vivo evaluation using porcine skin displayed efficient and steady state flux of 5-FU from the biodegradable

  16. BIODEGRADABLE COATING FROM AGATHIS ALBA

    Directory of Open Access Journals (Sweden)

    NORYAWATI MULYONO

    2012-11-01

    Full Text Available The adhesive property of copal makes it as a potential coating onto aluminum foil to replace polyethylene. This research aimed to develop copal-based coating. The coating was prepared by extracting the copal in ethyl acetate and dipping the aluminium foil in ethyl acetate soluble extract of copal. The characterization of coating included its thickness, weight, thermal and chemical resistance, and biodegradation. The results showed that the coating thickness and weight increased as the copal concentration and dipping frequency increased. Thermal resistance test showed that the coating melted after being heated at 110°C for 30 min. Copal-based coating wasresistant to acidic solution (pH 4.0, water, and coconut oil, but was deteriorated in detergent 1% (w/v and basic solution (pH 10.0. Biodegradability test using Pseudomonas aeruginosa showed weight reduction of 76.82% in 30 days.

  17. Biomedical Applications of Biodegradable Polyesters

    Directory of Open Access Journals (Sweden)

    Iman Manavitehrani

    2016-01-01

    Full Text Available The focus in the field of biomedical engineering has shifted in recent years to biodegradable polymers and, in particular, polyesters. Dozens of polyester-based medical devices are commercially available, and every year more are introduced to the market. The mechanical performance and wide range of biodegradation properties of this class of polymers allow for high degrees of selectivity for targeted clinical applications. Recent research endeavors to expand the application of polymers have been driven by a need to target the general hydrophobic nature of polyesters and their limited cell motif sites. This review provides a comprehensive investigation into advanced strategies to modify polyesters and their clinical potential for future biomedical applications.

  18. Ecological response to hydrological variability and catchment development: Insights from a shallow oxbow lake in Lower Mississippi Valley, Arkansas.

    Science.gov (United States)

    Bhattacharya, Ruchi; Hausmann, Sonja; Hubeny, J Bradford; Gell, Peter; Black, Jessica L

    2016-11-01

    The ecological response of shallow oxbow lakes to variability in hydrology and catchment development in large river floodplain ecosystems (RFE) in Arkansas remains largely unknown. Investigating these responses will advance our understanding of ecological evolution of oxbow lakes in response to the major environmental drivers, which will establish baseline conditions required to develop effective management practices for RFE. In this pilot study, we examined the potential of using a dated surface sediment core from Adams Bayou, a floodplain lake located within the Cache-Lower White River Ramsar site in SE Arkansas. Stratigraphic records of diatoms and sediment geochemistry were used to ascertain variation in Adams Bayou's ecological condition. During 1968-2008, in response to hydrological and anthropogenic changes, Adams Bayou's diatom assemblages progressed from predominantly benthic (Gomphonema parvulum and Meridion circulare) to primarily planktonic assemblage (Aulacoseira granulata and Cyclotella meneghiniana), along with a decrease in magnetic susceptibility (k) and % silt. Statistical analyses reveled that during 1968-2000, higher hydrological connectivity and catchment alterations drove Adams Bayou's ecosystem. After 2000, lower hydrological connectivity and increase in cultivation were the major drivers. The potential impact of increasing air temperature was also noted. The shift in Adams Bayou from a connected, clear, mesotrophic state to a relatively isolated, turbid and nutrient enriched state is consistent with regime shift models and highlights its sensitivity to a combination of environmental stresses prevalent in the catchment. Although fluvial systems pose challenges in establishing clear chronologies, oxbow lake sediments can be a effective paleoecological archives. Our work provides clear evidence for the change in the ecological character of this wetland of international significance and flags the need for a wider assessment of water bodies

  19. Anaerobic Biodegradation of Detergent Surfactants

    OpenAIRE

    Erich Jelen; Ute Merrettig-Bruns

    2009-01-01

    Detergent surfactantscan be found in wastewater in relevant concentrations. Most of them are known as ready degradable under aerobic conditions, as required by European legislation. Far fewer surfactants have been tested so far for biodegradability under anaerobic conditions. The natural environment is predominantly aerobic, but there are some environmental compartments such as river sediments, sub-surface soil layer and anaerobic sludge digesters of wastewater treatment plants which have str...

  20. Can you escape the beat? Modelling spatiotemporal biodegradation dynamics during periodic disturbances

    Science.gov (United States)

    König, Sara; Worrich, Anja; Wick, Lukas Y.; Miltner, Anja; Kästner, Matthias; Thullner, Martin; Centler, Florian; Banitz, Thomas; Frank, Karin

    2016-04-01

    Biodegradation of organic compounds in soil is an important microbial ecosystem service. Soil ecosystems are constantly exposed to disturbances of different spatial configurations and frequencies, challenging their ability to recover the biodegradation function. Thus, the response to these disturbances is crucial for the soil systems' biodegradation performance. The influence of spatial aspects of the disturbance regimes on long-term biodegradation dynamics under periodic disturbances has not been examined, yet. We applied a numerical simulation model considering bacterial growth, degradation, and dispersal to analyze the spatiotemporal biodegradation dynamics under disturbances occuring with different frequencies and with different spatial configurations. We found biodegradation performance decreasing in response to periodic disturbances but on average approaching a new quasi steady state. This mean performance of the disturbed systems increases with both, the interval length between disturbance events and the fragmentation of the spatial disturbance patterns. A detailed spatiotemporal analysis of degradation activity reveals that under highly fragmented disturbance patterns, biodegradation still takes place in the entire disturbed area. For moderately fragmented disturbance patterns, parts of the disturbed area become completely inactive. However, areas with high degradation activity emerge at the interface between disturbed and undisturbed areas, allowing the systems to maintain a relatively high degradation performance. Further decreasing the disturbance patterns' fragmentation, fewer interfaces between disturbed and undisturbed area and, thus, fewer active habitats occur, which reduces biodegradation performances. In additional simulations, we found that bacterial dispersal networks, as for example provided by fungal hyphae, usually increase the areas of high degradation activity and, thus, the biodegradation performance in presence of periodic disturbances

  1. Engineering Flame Retardant Biodegradable Nanocomposites

    Science.gov (United States)

    He, Shan; Yang, Kai; Guo, Yichen; Zhang, Linxi; Pack, Seongchan; Davis, Rachel; Lewin, Menahem; Ade, Harald; Korach, Chad; Kashiwagi, Takashi; Rafailovich, Miriam

    2013-03-01

    Cellulose-based PLA/PBAT polymer blends can potentially be a promising class of biodegradable nanocomposites. Adding cellulose fiber reinforcement can improve mechanical properties of biodegradable plastics, but homogeneously dispersing hydrophilic cellulose in the hydrophobic polymer matrix poses a significant challenge. We here show that resorcinol diphenyl phosphates (RDP) can be used to modify the surface energy, not only reducing phase separation between two polymer kinds but also allowing the cellulose particles and the Halloysite clay to be easily dispersed within polymer matrices to achieve synergy effect using melt blending. Here in this study we describe the use of cellulose fiber and Halloysite clay, coated with RDP surfactant, in producing the flame retardant polymer blends of PBAT(Ecoflex) and PLA which can pass the stringent UL-94 V0 test. We also utilized FTIR, SEM and AFM nanoindentation to elucidate the role RDP plays in improving the compatibility of biodegradable polymers, and to determine structure property of chars that resulted in composites that could have optimized mechanical and thermal properties. Supported by Garcia Polymer Center and NSF Foundation.

  2. Response of waves and coastline evolution to climate variability off the Niger Delta coast during the past 110 years

    Science.gov (United States)

    Dada, Olusegun A.; Li, Guangxue; Qiao, Lulu; Ma, Yanyan; Ding, Dong; Xu, Jishang; Li, Pin; Yang, Jichao

    2016-08-01

    River deltas, low-lying landforms that host critical economic infrastructures and diverse ecosystems as well as high concentrations of human population, are highly vulnerable to the effects of global climate change. In order to understand the wave climate, their potential changes and implication on coastline evolution for environment monitoring and sustainable management of the Niger Delta in the Gulf of Guinea, an investigation was carried out based on offshore wave statistics of an 110-year time series (1900-2010) dataset obtained from the ECMWF ERA-20C atmospheric reanalysis. Results of multivariate regression analyses indicate that interannual mean values of Hs and Tm trends tended to increase over time, especially in the western part of the delta coast, so that they are presently (1980 and 2010) up to 264 mm (300%) and 0.32 s (22%), respectively, higher than 80 years (1900-1930) ago. The maximum directions of the wave have become more westerly (southward) than southerly (westward) by up to 2° (33%) and the mean longshore sediment transport rate has increased by more than 8% over the last 80 years. The linear regression analysis for shoreline changes from 1987 to 2013 shows an erosional trend at the western part of the delta and accretional trends towards eastern part. The relationship between wave climate of the study area and atmospheric circulation using Pearson's correlation shows that the Atlantic Multidecadal Oscillation (AMO), North Atlantic Oscillation (NAO), East Atlantic pattern (EA) and El-Nino/Southern Oscillation (ENSO) Index explain significant proportion of the seasonal and annual wave variabilities compared to other indices. But it is most likely that the combination of these climatic indices acting together or separately constitutes a powerful and effective mechanism responsible for much of the variability of the offshore Niger Delta wave climate. The study concludes that changing wave climate off the Niger Delta has strong implications on the

  3. Understanding vegetation response to climate variability from space: the scientific objectives, the approach and the concept of the SPECTRA Mission

    Science.gov (United States)

    Menenti, M.

    2002-06-01

    The response of vegetation to climate variability is a major scientific question. The monitoring of the carbon stock in terrestrial environments, as well as the improved understanding of the surface-atmosphere interactions controlling the exchange of matter, energy and momentum, is of immediate interest for an improved assessment of the various components of the global carbon cycle. Studies of the Earth System processes at the global scale rely on models that require an advanced understanding and proper characterization of processes at smaller scales. The goal of the SPECTRA mission is to improve the description of those processes by means of better constraints on and parameterizations of the associated models. Many vegetation properties are related to features of reflectance spectra in the region 400 nm - 2500 nm. Detailed observations of spectral reflectance reveal subtle features related to biochemical components of leaves such as chlorophyll and water. The architecture of vegetation canopies determines complex changes of observed reflectance spectra with view and illumination angle. Quantitative analysis of reflectance spectra requires, therefore, an accurate characterization of the anisotropy of reflected radiance. This can be achieved with nearly simultaneous observations at different view angles. Exchange of energy between the biosphere and the atmosphere is an important mechanism determining the response of vegetation to climate variability. This requires measurements of the component temperature of foliage and soil. The prime objective of SPECTRA is to determine the amount, assess the conditions and understand the response of terrestrial vegetation to climate variability and its role in the coupled cycles of energy, water and carbon. The amount and state of vegetation will be determined by the combination of observed vegetation properties and data assimilation. Specifically, the mission will characterize the amount and state of vegetation with observations

  4. Understanding vegetation response to climate variability from space the scientific objectives, the approach and the concept of the Spectra Mission

    Science.gov (United States)

    Menenti, M.; Rast, M.; Baret, F.; Hurk, B.; Knorr, W.; Mauser, W.; Miller, J.; Schaepman, M.; Schimel, D.; Verstraete, M.

    The response of vegetation to climate variability is a major scientific question. The monitoring of the carbon stock in terrestrial environments, as well as the improved understanding of the surface-atmosphere interactions controlling the exchange of matter, energy and momentum, is of immediate interest for an improved assessment of the various components of the global carbon cycle. Studies of the Earth System processes at the global scale rely on models that require an advanced understanding and proper characterization of processes at smaller scales. The goal of the SPECTRA mission is to improve the description of those processes by means of better constraints on and parameterizations of the associated models. Many vegetation properties are related to features of reflectance spectra in the region 400 nm - 2500 nm. Detailed observations of spectral reflectance reveal subtle features related to biochemical components of leaves such as chlorophyll and water. The architecture of vegetation canopies determines complex changes of observed reflectance spectra with view and illumination angle. Quantitative analysis of reflectance spectra requires, therefore, an accurate characterization of the anisotropy of reflected radiance. This can be achieved with nearly - simultaneous observations at different view angles. Exchange of energy between the biosphere and the atmosphere is an important mechanism determining the response of vegetation to climate variability. This requires measurements of the component t mperature ofe foliage and soil. The prime objective of SPECTRA is to determine the amount, assess the conditions and understand the response of terrestrial vegetation to climate variability and its role in the coupled cycles of energy, water and carbon. The amount and state of vegetation will be determined by the combination of observed vegetation properties and data assimilation. Specifically, the mission will characterize the amount and state of vegetation with

  5. Understanding Vegetation Response To Climate Variability From Space: The Scientific Objectives< The Approach and The Concept of The Spectra Mission

    Science.gov (United States)

    Menenti, M.; Rast, M.; Baret, F.; Mauser, W.; Miller, J.; Schaepman, M.; Schimel, D.; Verstraete, M.

    The response of vegetation to climate variability is a major scientific question. The monitoring of the carbon stock in terrestrial environments, as well as the improved understanding of the surface-atmosphere interactions controlling the exchange of mat- ter, energy and momentum, is of immediate interest for an improved assessment of the various components of the global carbon cycle. Studies of the Earth System processes at the global scale rely on models that require an advanced understanding and proper characterization of processes at smaller scales. The goal of the SPECTRA mission is to improve the description of those processes by means of better constraints on and parameterizations of the associated models. Many vegetation properties are related to features of reflectance spectra in the region 400 nm U 2500 nm. Detailed observa- tions of spectral reflectance reveal subtle features related to biochemical components of leaves such as chlorophyll and water. The architecture of vegetation canopies de- termines complex changes of observed reflectance spectra with view and illumination angle. Quantitative analysis of reflectance spectra requires, therefore, an accurate char- acterization of the anisotropy of reflected radiance. This can be achieved with nearly U simultaneous observations at different view angles. Exchange of energy between the biosphere and the atmosphere is an important mechanism determining the response of vegetation to climate variability. This requires measurements of the component tem- perature of foliage and soil. The prime objective of SPECTRA is to determine the amount, assess the conditions and understand the response of terrestrial vegetation to climate variability and its role in the coupled cycles of energy, water and carbon. The amount and state of vegetation will be determined by the combination of observed vegetation properties and data assimilation. Specifically, the mission will character- ize the amount and state of vegetation

  6. A Methodology to Infer Crop Yield Response to Climate Variability and Change Using Long-Term Observations

    Directory of Open Access Journals (Sweden)

    Manfred A. Lange

    2013-11-01

    Full Text Available A new methodology to extract crop yield response to climate variability and change from long-term crop yield observations is presented in this study. In contrast to the existing first-difference approach (FDA, the proposed methodology considers that the difference in value between crop yields of two consecutive years reflects necessarily the contributions of climate and management conditions, especially at large spatial scales where both conditions may vary significantly from one year to the next. Our approach was applied to remove the effect of non-climatic factors on crop yield and, hence, to isolate the effect of the observed climate change between 1961 and 2006 on three widely crops grown in three Mediterranean countries—namely wheat, corn and potato—using national-level crop yield observations’ time-series. Obtained results show that the proposed methodology provides us with a ground basis to improve substantially our understanding of crop yield response to climate change at a scale that is relevant to large-scale estimations of agricultural production and to food security analyses; and therefore to reduce uncertainties in estimations of potential climate change effects on agricultural production. Furthermore, a comparison of outputs of our methodology and FDA outputs yielded a difference in terms of maize production in Egypt, for example, that exceeds the production of some neighbouring countries.

  7. Grazing game: a learning tool for adaptive management in response to climate variability in semiarid areas of Ghana

    Directory of Open Access Journals (Sweden)

    Grace B. Villamor

    2016-03-01

    Full Text Available In West Africa, the most extreme predicted effects of climate change are expected to occur in desert and grassland areas. It is crucial for local populations in this region to better understand what such projections signify to them to identify sound adaptation policies and interventions. We developed a game, called the "grazing game," and conducted trials with local farmers at multiple study sites as a learning tool to better understand their behavior in response to climate variability under semiarid conditions in West Africa and to facilitate social learning. The grazing game was designed to reveal the processes that lead to overgrazing and desertification based on the players' interactions with environmental conditions and their resulting decisions. We conducted a total of 23 game trials around the Vea catchment of the Upper East Region of Ghana involving 243 individual farmers. From the games, local farmers exhibited a very positive response to how the game replicated rainfall fluctuations that they currently experience and led to the identification of coping strategies, such as selling cows, seeking government assistance, and engaging in alternative livelihood means. Participating farmers tended to avoid uncertain situations and sought to simplify their decisions, and the game provided insight into the rich local ecological knowledge of environmental indicators. Based on the game trial results, we found that the game facilitated instrumental and communicative learning among the players and facilitators. Further, the game served as a platform where players could share their views, knowledge, and perceptions of climate-related issues.

  8. A review of plastic waste biodegradation.

    Science.gov (United States)

    Zheng, Ying; Yanful, Ernest K; Bassi, Amarjeet S

    2005-01-01

    With more and more plastics being employed in human lives and increasing pressure being placed on capacities available for plastic waste disposal, the need for biodegradable plastics and biodegradation of plastic wastes has assumed increasing importance in the last few years. This review looks at the technological advancement made in the development of more easily biodegradable plastics and the biodegradation of conventional plastics by microorganisms. Additives, such as pro-oxidants and starch, are applied in synthetic materials to modify and make plastics biodegradable. Recent research has shown that thermoplastics derived from polyolefins, traditionally considered resistant to biodegradation in ambient environment, are biodegraded following photo-degradation and chemical degradation. Thermoset plastics, such as aliphatic polyester and polyester polyurethane, are easily attacked by microorganisms directly because of the potential hydrolytic cleavage of ester or urethane bonds in their structures. Some microorganisms have been isolated to utilize polyurethane as a sole source of carbon and nitrogen source. Aliphatic-aromatic copolyesters have active commercial applications because of their good mechanical properties and biodegradability. Reviewing published and ongoing studies on plastic biodegradation, this paper attempts to make conclusions on potentially viable methods to reduce impacts of plastic waste on the environment.

  9. Biodegradation of high molecular weight polylactic acid

    Science.gov (United States)

    Stloukal, Petr; Koutny, Marek; Sedlarik, Vladimir; Kucharczyk, Pavel

    2012-07-01

    Polylactid acid seems to be an appropriate replacement of conventional non-biodegradable synthetic polymer primarily due to comparable mechanical, thermal and processing properties in its high molecular weight form. Biodegradation of high molecular PLA was studied in compost for various forms differing in their specific surface area. The material proved its good biodegradability under composting conditions and all investigated forms showed to be acceptable for industrial composting. Despite expectations, no significant differences in resulting mineralizations were observed for fiber, film and powder sample forms with different specific surface areas. The clearly faster biodegradation was detected only for the thin coating on porous material with high specific surface area.

  10. Study on biodegradable aromatic/aliphatic copolyesters

    Energy Technology Data Exchange (ETDEWEB)

    Yiwang Chen; Licheng Tan; Lie Chen; Yan, Yang; Xiaofeng Wang [Nanchang University, Nanchang (China). School of Materials Science and Engineering. Inst. of Polymer Materials]. E-mail: ywchen@ncu.edu.cn

    2008-04-15

    Progress on biodegradable aromatic/aliphatic copolyesters based on aliphatic and aromatic diacids, diols and ester monomers was reviewed. The aromatic/aliphatic copolyesters combined excellent mechanical properties with biodegradability. Physical properties and biodegradability of copolyesters varied with chain length of the aliphatic polyester segment and atacticity of copolyesters. The process ability of copolyesters could be improved significantly after incorporating a stiff chain segment through copolymerization of aliphatic polyesters with an aromatic liquid crystal element. The aromatic/aliphatic copolyesters as a new type of biodegradable materials could replace some general plastics in certain applications, namely biomedical and environmental friendly fields. (author)

  11. Biodegradable materials as foundry moulding sands binders

    Directory of Open Access Journals (Sweden)

    K. Major - Gabryś

    2015-07-01

    Full Text Available The aim of this article is to show the possibility of using biodegradable materials as part of the composition of foundry moulding and core sand binders. Research shows that moulding sands with biodegradable materials selected as binders are not only less toxic but are also better suited to mechanical reclamation than moulding sands with phenol-furfuryl resin. The use of biodegradable materials as additives to typical synthetic resins can result in their decreased toxicity and improved ability to reclamation as well as in accelerated biodegradation of binding material leftovers of mechanical reclamation.

  12. Use of Frequency Response Metrics to Assess the Planning and Operating Requirements for Reliable Integration of Variable Renewable Generation

    Energy Technology Data Exchange (ETDEWEB)

    Eto, Joseph H.; Undrill, John; Mackin, Peter; Daschmans, Ron; Williams, Ben; Haney, Brian; Hunt, Randall; Ellis, Jeff; Illian, Howard; Martinez, Carlos; O' Malley, Mark; Coughlin, Katie; LaCommare, Kristina Hamachi

    2010-12-20

    An interconnected electric power system is a complex system that must be operated within a safe frequency range in order to reliably maintain the instantaneous balance between generation and load. This is accomplished by ensuring that adequate resources are available to respond to expected and unexpected imbalances and restoring frequency to its scheduled value in order to ensure uninterrupted electric service to customers. Electrical systems must be flexible enough to reliably operate under a variety of"change" scenarios. System planners and operators must understand how other parts of the system change in response to the initial change, and need tools to manage such changes to ensure reliable operation within the scheduled frequency range. This report presents a systematic approach to identifying metrics that are useful for operating and planning a reliable system with increased amounts of variable renewable generation which builds on existing industry practices for frequency control after unexpected loss of a large amount of generation. The report introduces a set of metrics or tools for measuring the adequacy of frequency response within an interconnection. Based on the concept of the frequency nadir, these metrics take advantage of new information gathering and processing capabilities that system operators are developing for wide-area situational awareness. Primary frequency response is the leading metric that will be used by this report to assess the adequacy of primary frequency control reserves necessary to ensure reliable operation. It measures what is needed to arrest frequency decline (i.e., to establish frequency nadir) at a frequency higher than the highest set point for under-frequency load shedding within an interconnection. These metrics can be used to guide the reliable operation of an interconnection under changing circumstances.

  13. Inter-individual variability in the response of human peripheral blood lymphocytes to ionizing radiation: comparison of the dicentric and micronucleus assays.

    Science.gov (United States)

    Pajic, Jelena; Rakic, Boban; Rovcanin, Branislav; Jovicic, Dubravka; Novakovic, Ivana; Milovanovic, Aleksandar; Pajic, Vesna

    2015-08-01

    Ionizing radiation can induce a wide range of DNA damage that leads to chromosomal aberrations. Some of those aberrations (dicentrics and micronuclei) are applied in biodosimetry. Biological dosimetry assumes similar radiosensitivity of each donor, but it does not exclude inter-individual variations in radiation susceptibility. Therefore, for biological reasons, it is always challenging to investigate inter-individual variability in response to radiation. For mechanistic reasons, it is also interesting to investigate the correlation between dicentric and micronuclei formation in response to radiation. In this experiment, irradiated blood specimens from 14 healthy male and female donors have been used to evaluate inter-individual variability in response to the genotoxic effects of X-ray radiation, as well as the dose-response relationship and test sensitivity using two endpoints (dicentrics and micronuclei). The results showed similar patterns of cytogenetic biomarker distribution between donors, but differences in the response of some donors at some doses. Data also showed that responses of male donors were better detected using the dicentric test, while for females, micronucleus frequencies were higher in response to the same dose of radiation. No influence of smoking status or age on specific responses was observed. Group variability in response to radiation was evaluated using coefficient of variation for each group of individuals irradiated with the same doses; as the dose increases, group variability becomes substantially lower. Despite sporadic inter-individual variability, trend of radiation-induced changes was similar. Produced calibration curves for both types of damage revealed dicentrics as genetic damage more typical for radiation than micronuclei.

  14. ADAPTATION OF AQUIFER MICROBIAL COMMUNITIES TO THE BIODEGRADATION OF XENOBIOTIC COMPOUNDS: INFLUENCE OF SUBSTRATE CONCENTRATION AND PREEXPOSURE

    Science.gov (United States)

    Studies were conducted to examine the adaptation response of aquifer microbial communities to xenobiotic compounds and the influence of chemical preexposure in the laboratory and in situ on adaptation. Adaptation and biodegradation were assessed as mineralization and cellular inc...

  15. Wood {delta}13C, {delta}18O and radial growth responses of residual red pine to variable retention harvesting.

    Science.gov (United States)

    Powers, Matthew D; Pregitzer, Kurt S; Palik, Brian J; Webster, Christopher R

    2010-03-01

    Variable retention harvests are used to enhance the development of structural complexity in managed forests by retaining living trees and other structural legacies from the pre-harvest ecosystem. While harvesting should increase resource availability to residual trees, greater crown exposure may also increase environmental stress, which makes it difficult to predict growth in different structural environments. We used stable carbon isotope ratios (delta(13)C) of annual rings from red pine trees (Pinus resinosa Ait.) as an index of intrinsic water use efficiency (iWUE), the ratio of photosynthetic carbon assimilation (A) to stomatal conductance (g(s)), to better understand how differences in physiological performance relate to growth responses following harvests that left residuals dispersed, aggregated between small (0.1 ha) gaps or aggregated between large (0.3 ha) gaps. Stable oxygen isotope ratios (delta(18)O) were used as an index of g(s) to investigate the drivers behind changes in iWUE. Retention harvesting did not appear to affect delta(13)C or delta(18)O at the stand scale when compared to unharvested control stands, but there was a significant, negative correlation between residual tree delta(13)C and plot basal area in the second and third years after harvesting that suggests declining iWUE as overstory competition increases. Residual tree delta(18)O was similar across treatments and basal areas. Trees in variable retention harvests showed small but positive increases in radial growth from the pre-treatment to post-treatment measurement periods, while radial growth declined in unharvested control stands. There were no significant differences in radial growth among retention treatments. Our results suggest residual red pine in relatively open environments benefit from greater A but do not show evidence of changes in g(s) that would indicate altered water relations.

  16. Comparative evaluation of central venous pressure and sonographic inferior vena cava variability in assessing fluid responsiveness in septic shock

    Directory of Open Access Journals (Sweden)

    Manjri Garg

    2016-01-01

    Full Text Available Objective: Fluid infusion, the most critical step in the resuscitation of patients with septic shock, needs preferably continuous invasive hemodynamic monitoring. The study was planned to evaluate the efficacy of ultrasonographically measured inferior vena cava collapsibility index (IVC CI in comparison to central venous pressure (CVP in predicting fluid responsiveness in septic shock. Materials and Methods: Thirty-six patients of septic shock requiring ventilatory support (invasive/noninvasive were included. Patients with congestive heart failure, raised intra-abdominal pressure, and poor echo window were excluded from the study. They were randomly divided into two groups based on mode of fluid resuscitation - Group I (CVP and Group II (IVC CI. Primary end-points were mean arterial pressure (MAP of ≥65 mmHg and CVP >12 mmHg or IVC CI <20% in Groups I and II, respectively. Patients were followed till achievement of end-points or maximum of 6 h. Outcome variables (pulse rate, MAP, urine output, pH, base deficit, and ScvO 2 were serially measured till the end of the study. Survival at 2 and 4 weeks was used as secondary end-point. Results: Primary end-point was reached in 31 patients (15 in Group I and 16 in Group II. Fluid infusion, by either method, had increased CVP and decreased IVC CI with resultant negative correlation between them (Pearson correlation coefficient -0.626. There was no significant difference in the amount of fluid infused and time to reach end-point in two groups. Comparison in outcome variables at baseline and end-point showed no significant difference including mortality. Conclusion: CVP and IVC CI are negatively correlated with fluid resuscitation, and both methods can be used for resuscitation, with IVC CI being noninferior to CVP.

  17. Synergy of environmental variables alters the thermal window and heat shock response: an experimental test with the crab Pachygrapsus marmoratus.

    Science.gov (United States)

    Madeira, Diana; Narciso, Luís; Diniz, Mário Sousa; Vinagre, Catarina

    2014-07-01

    The intertidal zone is an extremely variable habitat, imposing stressful conditions on its inhabiting communities. Tolerance towards extremes of temperature, salinity and pH are crucial in these habitats. Despite the vast literature on stress tolerance, few studies have focused on the synergistic effects of several variables on thermal tolerance and HSP70 (heat shock protein 70 kDa) levels. In this work, the crabs were exposed to three experimental conditions 1) thermal ramp at standard pH (8) and saline conditions (35‰) (named T), 2) thermal ramp at standard pH (8) and hyposaline conditions (15‰) (named T plus HypoS), and 3) thermal ramp at lower pH (7) and standard saline conditions (35‰) (named T plus A). Two physiological parameters (Critical Thermal Maximum - CTMax, and osmolality) and a stress biomarker (HSP70) were chosen for this analysis. These parameters were measured in all of the aforementioned conditions. CTMax for each set of conditions was reached by exposing the organisms to a rate of temperature increase of 1 °C h(-1) until loss of equilibrium. Haemolymph samples were taken every 2 °C to quantify HSP70 and osmolality. Results showed that CTMax did not differ between crabs solely exposed to T stress and crabs exposed to T plus HypoS stress. However, HSP70 production was impaired in T plus HypoS stress. When crabs were exposed to T plus A stress, they showed a significantly higher CTMax, suggesting that short-term exposure to acidified conditions may alter the thermal window of this species. Nevertheless, in T plus A conditions HSP70 production was impaired as well. Regarding osmolality it decreased according to temperature increase in all tested stress conditions. This study showed that the heat stress response is altered by the synergistic effect of variables. Physiological end-points (i.e. CTMax) may vary and the expression of stress proteins such as HSP70 may be impaired.

  18. Decision-making considerations in application of biodegradable fixation systems in maxillofacial surgery--a retrospective cohort study.

    Science.gov (United States)

    van Bakelen, N B; Buijs, G J; Jansma, J; de Visscher, J G A M; Hoppenreijs, Th J M; Bergsma, J E; Stegenga, B; Bos, R R M

    2014-07-01

    In a recent RCT comparing biodegradable (Inion CPS) with titanium (KLS Martin) plates and screws for fixation of osteotomies or fractures, we found that in 21% of the cases the surgeon decided intra-operatively to switch from biodegradable to titanium. The aim of the current retrospective cohort study was to analyse the reasons for these switches in order to find predictor variables that may be helpful in the decision to use biodegradable devices or not. The surgeons' opinion about the biodegradable system, and if there was a learning curve in the application of the biodegradable system were also investigated. All variables were assessed during the original RCT by using a questionnaire that was completed by the OMF surgeon directly post-operatively. For the outcome variable "surgeons' opinion" a separate questionnaire was used. Regarding the predictor variables a mandibular fracture had a higher risk of switching compared to a BSSO. However, looking at the reasons for these switches no firm conclusions can be drawn. There was a subjective learning curve to acquire the application-skills for the biodegradable system. There were no changes in isolated Le-Fort-I osteotomies despite the fact that the biodegradable system seems more difficult to apply in the midface. Inadequate stability was the main reason for switching. This can be material-related, or related to inexperience with or lack of confidence in the system, or impatience of the surgeon. A learning curve and personal preferences probably play an important role in the decision to switch. We think that with more patience and more experience it should be possible to increase both user comfort and confidence in the biodegradable system of Inion CPS, which likely will decrease the number of intra-operative switches.

  19. Batch phenol biodegradation study and application of factorial experimental design

    Directory of Open Access Journals (Sweden)

    A. Hellal

    2010-01-01

    Full Text Available A bacterium, Pseudomonas aeruginosa (ATTC27853, was investigated for its ability to grow and to degrade phenol as solecarbon source, in aerobic batch culture. The parameters which affect the substrate biodegradation such as the adaptation ofbacteria to phenol, the temperature, and the nature of the bacteria were investigated. The results show that for a range oftemperature of 30 to 40°C, the best degradation of phenol for a concentration of 100mg/l was observed at 30°C. The regenerationof the bacterium which allows the reactivation of its enzymatic activity, shows that the degradation of 100 mg/ l ofsubstrate at 30° C required approximately 50 hours with revivified bacteria, while it only starts after 72 hours for those norevivified. Adapted to increasing concentrations, allows the bacteria to degrade a substrate concentration of about 400mg/l in less than 350 hours.A second part was consisted in the determination of a substrate degradation model using the factorial experiment design,as a function of temperature (30-40°C and of the size of the inoculums (260.88 - 521.76mg/ l. The results were analyzedstatistically using the Student’s t-test, analysis of variance, and F-test. The value of R2 (0.99872 and adjusted R2 (0.9962close to 1.0, verifies the good correlation between the observed and the predicted values, and provides the excellent relationshipbetween the independent variables (factors and the response (the time of the phenol degradation. F-value found above200, indicates that the considered model is statistically significant.

  20. Modeling the response of primary production and sedimentation to variable nitrate loading in the Mississippi River plume

    Science.gov (United States)

    Green, Rebecca E.; Breed, Greg A.; Dagg, Michael J.; Lohrenz, Steven E.

    2008-07-01

    Increases in nitrate loading to the Mississippi River watershed during the last 50 years are considered responsible for the increase in hypoxic zone size in Louisiana-Texas shelf bottom waters. There is currently a national mandate to decrease the size of the hypoxic zone to 5000 km 2 by 2015, mostly by a 30% reduction in annual nitrogen discharge into the Gulf of Mexico. We developed an ecosystem model for the Mississippi River plume to investigate the response of organic matter production and sedimentation to variable nitrate loading. The nitrogen-based model consisted of nine compartments (nitrate, ammonium, labile dissolved organic nitrogen, bacteria, small phytoplankton, diatoms, micro- and mesozooplankton, and detritus), and was developed for the spring season, when sedimentation of organic matter from plume surface waters is considered important in the development of shelf hypoxia. The model was forced by physical parameters specified along the river-ocean salinity gradient, including residence time, light attenuation by dissolved and particulate matter, mixed layer depth, and dilution. The model was developed using measurements of biological biomasses and nutrient concentrations across the salinity gradient, and model validation was performed with an independent dataset of primary production measurements for different riverine NO 3 loads. Based on simulations over the range of observed springtime NO 3 loads, small phytoplankton contributed on average 80% to primary production for intermediate to high salinities (>15), and the main contributors to modeled sedimentation at these salinities were diatom sinking, microzooplankton egestion, and small phytoplankton mortality. We investigated the impact of limiting factors on the relationship between NO 3 loading and ecosystem rates. Model results showed that primary production was primarily limited by physical dilution of NO 3, followed by abiotic light attenuation, light attenuation due to mixing, and diatom

  1. Biodegradation study of some food packaging biopolymers based on PVA

    Directory of Open Access Journals (Sweden)

    Elena Elisabeta Tanase

    2016-03-01

    Full Text Available Abstract Polymers are a common choice as protective materials since they combine flexibility, variable sizes and shapes, relatively light weight, stability, resistance to breaking, barrier properties and perceived high-quality image with cost-effectiveness. Currently, mainly non-biodegradable petroleum-based synthetic polymers are used as packaging materials for foods, because of their availability, low cost and functionality. However, biopolymers can be made from renewable resources without the environmental issues of petroleum-based polymers and with the additional advantage of being available from renewable sources or as by-products or waste-products from the food and agriculture industries. The aim of this study was to test some food packaging biopolymers based on PVA. In this respect, some biopolymers for food packaging applications were subjected to biodegradation tests by covering the tested samples with soil. The samples were incubated in known temperature and humidity conditions. The experiment lasted 45 days, after that the samples were washed, weighed and the biodegradation degree was calculated. The obtained results shows that PVA is a promising material for food packaging usage, as it is made from renewable resources and it is environmentally friendly.

  2. SIFAT MEKANIK DAN MORFOLOGI PLASTIK BIODEGRADABLE DARI LIMBAH TEPUNG NASI AKING DAN TEPUNG TAPIOKA MENGGUNAKAN PEMLASTIK GLISEROL

    Directory of Open Access Journals (Sweden)

    Andri Cahyo Kumoro

    2014-10-01

    Full Text Available [Title: Mechanical Properties and Morfology of Biodegradable Plastic from Steamed Rice Waste and Cassava Flour with Glycerol as Plasticizer] The annual consumption of plastic packaging has increased significantly as a response to the increase of people’s need and buying power. As a packaging material, plastic is light, flexible, practical and inexpensive. Unfortunately, if the plastic is not biodegradable and dumped irresponsibly to the ecosystem may cause serious environmental problems. The objective of this research was to study the effect of glycerol on the characteristic of biodegradable plastic from steamed rice waste and cassava flours composites. The biodegradable plastic was manufactured by casting the warm solution of flours composite with addition of glycerol as plasticizer. The results showed that biodegradable plastic obtained from steamed rice waste and cassava flours composites has limited mechanical stress, but remains flexible in nature. Good quality biodegradable plastic was obtained when 15% weight of glycerol in addition to 30:70 ratio of steamed rice waste flour to cassava flour with tensile strength 20.65 MPa, elongation at break 4.7% and Young Modulus 1138 MPa. The biodegradable plastic exhibits discontinue microstructure, rough and porous. Fourier transform infrared analysis proved the existence of OH, CH2, amide III and amida I groups in the biodegradable plastic. 

  3. Environmentally Relevant Inoculum Concentrations Improve the Reliability of Persistent Assessments in Biodegradation Screening Tests.

    Science.gov (United States)

    Martin, Timothy J; Snape, Jason R; Bartram, Abigail; Robson, Aidan; Acharya, Kishor; Davenport, Russell J

    2017-02-23

    Standard OECD biodegradation screening tests (BSTs) have not evolved at the same rate as regulatory concerns, which now place an increased emphasis on environmental persistence. Consequently, many chemicals are falsely assigned as being potentially persistent based on results from BSTs. The present study increased test duration and increased inoculum concentrations to more environmentally relevant levels to assess their impact on biodegradation outcome and intratest replicate variability for chemicals with known environmental persistence. Chemicals were assigned to potential persistence categories based on existing degradation data. These more environmentally relevant BSTs (erBSTs) improved the reliability of persistence assignment by reducing the high variability associated with these tests and the occurrence of failures at low inoculum concentrations due to the exclusion of specific degraders. Environmental fate was determined using a reference set of (14)C-labeled compounds with a range of potential environmental persistences, and full mass balance data were collated. The erBST correctly assigned five reference chemicals of known biodegradabilities to their appropriate persistence category in contrast to a standard OECD Ready Biodegradation Test (RBTs, P < 0.05). The erBST was significantly more reproducible than an OECD RBT (ANOVA, P < 0.05), with more consistent rates and extent of biodegradation observed in the erBST.

  4. The Macaque Social Responsiveness Scale (mSRS: A Rapid Screening Tool for Assessing Variability in the Social Responsiveness of Rhesus Monkeys (Macaca mulatta.

    Directory of Open Access Journals (Sweden)

    Eric J Feczko

    Full Text Available Understanding the biological mechanisms underlying human neuropsychiatric disorders, such as autism spectrum disorder (ASD, has been hindered by the lack of a robust, translational animal model. Rhesus monkeys (Macaca mulatta display many of the same social behaviors that are affected in ASD, making them an excellent animal species in which to model social impairments. However, the social impairments associated with ASD may reflect extreme ends of a continuous distribution of traits. Thus, to validate the rhesus monkey as an animal model for studying social impairments that has strong translational relevance for ASD, researchers need an easily-implemented measurement tool that can quantify variation in social behavior dimensionally. The Social Responsiveness Scale (SRS is a 65-item survey that identifies both typical and atypical social behaviors in humans that covary with ASD symptom severity. A chimpanzee SRS has already been validated and the current study adapted this tool for use in the rhesus monkey (mSRS. Fifteen raters completed the mSRS for 105 rhesus monkeys living at the Yerkes National Primate Research Center. The mSRS scores showed a unimodal distribution with a positive skew that identified 6 statistical outliers. Inter-rater reliability was very strong, but only 17 of the 36 questions showed positive intra-item reliability. The results of an exploratory factor analysis identified 3 factors that explained over 60% of the variance, with 12 items significantly loading onto the primary factor. These items reflected behaviors associated with social avoidance, social anxiety or inflexibility and social confidence. These initial findings are encouraging and suggest that variability in the social responsiveness of rhesus monkeys can be quantified using the mSRS: a tool that has strong translational relevance for human disorders. With further modification, the mSRS may provide an promising new direction for research on the biological

  5. A compendium of temperature responses of Rubisco kinetic traits: variability among and within photosynthetic groups and impacts on photosynthesis modeling.

    Science.gov (United States)

    Galmés, Jeroni; Hermida-Carrera, Carmen; Laanisto, Lauri; Niinemets, Ülo

    2016-09-01

    The present study provides a synthesis of the in vitro and in vivo temperature responses of Rubisco Michaelis-Menten constants for CO2 (Kc) and O2 (Ko), specificity factor (Sc,o) and maximum carboxylase turnover rate (kcatc) for 49 species from all the main photosynthetic kingdoms of life. Novel correction routines were developed for in vitro data to remove the effects of study-to-study differences in Rubisco assays. The compilation revealed differences in the energy of activation (∆Ha) of Rubisco kinetics between higher plants and other photosynthetic groups, although photosynthetic bacteria and algae were under-represented and very few species have been investigated so far. Within plants, the variation in Rubisco temperature responses was related to species' climate and photosynthetic mechanism, with differences in ∆Ha for kcatc among C3 plants from cool and warm environments, and in ∆Ha for kcatc and Kc among C3 and C4 plants. A negative correlation was observed among ∆Ha for Sc/o and species' growth temperature for all data pooled, supporting the convergent adjustment of the temperature sensitivity of Rubisco kinetics to species' thermal history. Simulations of the influence of varying temperature dependences of Rubisco kinetics on Rubisco-limited photosynthesis suggested improved photosynthetic performance of C3 plants from cool habitats at lower temperatures, and C3 plants from warm habitats at higher temperatures, especially at higher CO2 concentration. Thus, variation in Rubisco kinetics for different groups of photosynthetic organisms might need consideration to improve prediction of photosynthesis in future climates. Comparisons between in vitro and in vivo data revealed common trends, but also highlighted a large variability among both types of Rubisco kinetics currently used to simulate photosynthesis, emphasizing the need for more experimental work to fill in the gaps in Rubisco datasets and improve scaling from enzyme kinetics to realized

  6. Canine sense and sensibility: tipping points and response latency variability as an optimism index in a canine judgement bias assessment.

    Directory of Open Access Journals (Sweden)

    Melissa J Starling

    Full Text Available Recent advances in animal welfare science used judgement bias, a type of cognitive bias, as a means to objectively measure an animal's affective state. It is postulated that animals showing heightened expectation of positive outcomes may be categorised optimistic, while those showing heightened expectations of negative outcomes may be considered pessimistic. This study pioneers the use of a portable, automated apparatus to train and test the judgement bias of dogs. Dogs were trained in a discrimination task in which they learned to touch a target after a tone associated with a lactose-free milk reward and abstain from touching the target after a tone associated with water. Their judgement bias was then probed by presenting tones between those learned in the discrimination task and measuring their latency to respond by touching the target. A Cox's Proportional Hazards model was used to analyse censored response latency data. Dog and Cue both had a highly significant effect on latency and risk of touching a target. This indicates that judgement bias both exists in dogs and differs between dogs. Test number also had a significant effect, indicating that dogs were less likely to touch the target over successive tests. Detailed examination of the response latencies revealed tipping points where average latency increased by 100% or more, giving an indication of where dogs began to treat ambiguous cues as predicting more negative outcomes than positive ones. Variability scores were calculated to provide an index of optimism using average latency and standard deviation at cues after the tipping point. The use of a mathematical approach to assessing judgement bias data in animal studies offers a more detailed interpretation than traditional statistical analyses. This study provides proof of concept for the use of an automated apparatus for measuring cognitive bias in dogs.

  7. Here today, gone tomorrow: biodegradable soft robots

    Science.gov (United States)

    Rossiter, Jonathan; Winfield, Jonathan; Ieropoulos, Ioannis

    2016-04-01

    One of the greatest challenges to modern technologies is what to do with them when they go irreparably wrong or come to the end of their productive lives. The convention, since the development of modern civilisation, is to discard a broken item and then procure a new one. In the 20th century enlightened environmentalists campaigned for recycling and reuse (R and R). R and R has continued to be an important part of new technology development, but there is still a huge problem of non-recyclable materials being dumped into landfill and being discarded in the environment. The challenge is even greater for robotics, a field which will impact on all aspects of our lives, where discards include motors, rigid elements and toxic power supplies and batteries. One novel solution is the biodegradable robot, an active physical machine that is composed of biodegradable materials and which degrades to nothing when released into the environment. In this paper we examine the potential and realities of biodegradable robotics, consider novel solutions to core components such as sensors, actuators and energy scavenging, and give examples of biodegradable robotics fabricated from everyday, and not so common, biodegradable electroactive materials. The realisation of truly biodegradable robots also brings entirely new deployment, exploration and bio-remediation capabilities: why track and recover a few large non-biodegradable robots when you could speculatively release millions of biodegradable robots instead? We will consider some of these exciting developments and explore the future of this new field.

  8. Primary biodegradation of petroleum hydrocarbons in seawater

    Energy Technology Data Exchange (ETDEWEB)

    Comber, M.I.H.; Den Haan, K.H.; Djemel, N.; Eadsforth, C.V.; King, D.; Paumen, M.L.; Parkerton, T.; Dmytrasz, B.

    2012-12-15

    This report describes primary biodegradation experiments performed to determine the persistence of higher molecular weight petroleum hydrocarbons in seawater. Results from the biodegradation experiments show that the majority of tested petroleum hydrocarbons have half-lives in seawater less than 60 days.

  9. Biodegradation of aliphatic and aromatic polycarbonates.

    Science.gov (United States)

    Artham, Trishul; Doble, Mukesh

    2008-01-01

    Polycarbonate is one of the most widely used engineering plastics because of its superior physical, chemical, and mechanical properties. Understanding the biodegradation of this polymer is of great importance to answer the increasing problems in waste management of this polymer. Aliphatic polycarbonates are known to biodegrade either through the action of pure enzymes or by bacterial whole cells. Very little information is available that deals with the biodegradation of aromatic polycarbonates. Biodegradation is governed by different factors that include polymer characteristics, type of organism, and nature of pretreatment. The polymer characteristics such as its mobility, tacticity, crystallinity, molecular weight, the type of functional groups and substituents present in its structure, and plasticizers or additives added to the polymer all play an important role in its degradation. The carbonate bond in aliphatic polycarbonates is facile and hence this polymer is easily biodegradable. On the other hand, bisphenol A polycarbonate contains benzene rings and quaternary carbon atoms which form bulky and stiff chains that enhance rigidity. Even though this polycarbonate is amorphous in nature because of considerable free volume, it is non-biodegradable since the carbonate bond is inaccessible to enzymes because of the presence of bulky phenyl groups on either side. In order to facilitate the biodegradation of polymers few pretreatment techniques which include photo-oxidation, gamma-irradiation, or use of chemicals have been tested. Addition of biosurfactants to improve the interaction between the polymer and the microorganisms, and blending with natural or synthetic polymers that degrade easily, can also enhance the biodegradation.

  10. Nylon biodegradation by lignin-degrading fungi.

    OpenAIRE

    Deguchi, T; Kakezawa, M; Nishida, T

    1997-01-01

    The biodegradation of nylon by lignin-degrading fungi was investigated. The fungus IZU-154 significantly degraded nylon-66 membrane under ligninolytic conditions. Nuclear magnetic resonance analysis showed that four end groups, CHO, NHCHO, CH3, and CONH2, were formed in the biodegraded nylon-66 membranes, suggesting that nylon-66 was degraded oxidatively.

  11. Biodegradation of Crystal Violet by Agrobacterium radiobacter

    DEFF Research Database (Denmark)

    Parshetti, G.K.; Parshetti, S.G.; Telke, A.A.

    2011-01-01

    and phenol. We proposed the hypothetical metabolic pathway of Crystal Violet biodegradation by A. radiobacter. Phytotoxicity and microbial toxicity study showed that Crystal Violet biodegradation metabolites were less toxic to bacteria (A. radiobacter, P. aurugenosa and A. vinelandii) contributing to soil...

  12. Bacterial biodegradation of neonicotinoid pesticides in soil and water systems.

    Science.gov (United States)

    Hussain, Sarfraz; Hartley, Carol J; Shettigar, Madhura; Pandey, Gunjan

    2016-12-01

    Neonicotinoids are neurotoxic systemic insecticides used in plant protection worldwide. Unfortunately, application of neonicotinoids affects both beneficial and target insects indiscriminately. Being water soluble and persistent, these pesticides are capable of disrupting both food chains and biogeochemical cycles. This review focuses on the biodegradation of neonicotinoids in soil and water systems by the bacterial community. Several bacterial strains have been isolated and identified as capable of transforming neonicotinoids in the presence of an additional carbon source. Environmental parameters have been established for accelerated transformation in some of these strains. Studies have also indicated that enhanced biotransformation of these pesticides can be accomplished by mixed microbial populations under optimised environmental conditions. Substantial research into the identification of neonicotinoid-mineralising bacterial strains and identification of the genes and enzymes responsible for neonicotinoid degradation is still required to complete the understanding of microbial biodegradation pathways, and advance bioremediation efforts.

  13. Current trends in biodegradable polyhydroxyalkanoates.

    Science.gov (United States)

    Chanprateep, Suchada

    2010-12-01

    The microbial polyesters known as polyhydroxyalkanoates (PHAs) positively impact global climate change scenarios by reducing the amount of non-degradable plastic used. A wide variety of different monomer compositions of PHAs has been described, as well as their future prospects for applications where high biodegradability or biocompatibility is required. PHAs can be produced from renewable raw materials and are degraded naturally by microorganisms that enable carbon dioxide and organic compound recycling in the ecosystem, providing a buffer to climate change. This review summarizes recent research on PHAs and addresses the opportunities as well as challenges for their place in the global market.

  14. Ultrastructural localization of highly variable 185/333 immune response proteins in the coelomocytes of the sea urchin, Heliocidaris erythrogramma.

    Science.gov (United States)

    Dheilly, Nolwenn M; Birch, Debra; Nair, Sham V; Raftos, David A

    2011-11-01

    The 185/333 proteins of sea urchins represent a family of highly variable immune response molecules with unknown functions. In this study, we show that 185/333 proteins are expressed by three cell types: amoebocytes, colourless spherule cells and gut-associated amoebocytes. A sub-population of amoebocytes express 185/333 proteins on the membranes of vesicles emanating from the trans-Golgi and which later fuse with the plasma membranes of the cells. The previously uncharacterized gut-associated amoebocytes also show a high level of 185/333 protein expression on their internal vesicles and plasma membranes. Colourless spherule cells contain 185/333 proteins within large spherules (specialized intracellular vesicles). In the presence of bacteria and yeast, the ultrastucture of colourless spherule cells changes and 185/333 proteins disappear. In contrast, 185/333 proteins were not found in the phagosomes of coelomocytes. The 185/333-positive gut amoebocytes were often associated with anuclear bodies, which appeared to incorporate material of microbial origin that was surrounded by 185/333 proteins. The association between 185/333 proteins on gut amoebocytes and anuclear bodies suggests that these proteins may be involved in the phagocytosis of microbes in the gut epithelium.

  15. Cortisol release, heart rate and heart rate variability in the horse and its rider: different responses to training and performance.

    Science.gov (United States)

    von Lewinski, Mareike; Biau, Sophie; Erber, Regina; Ille, Natascha; Aurich, Jörg; Faure, Jean-Michel; Möstl, Erich; Aurich, Christine

    2013-08-01

    Although some information exists on the stress response of horses in equestrian sports, the horse-rider team is much less well understood. In this study, salivary cortisol concentrations, heart rate (HR) and heart rate variability (HRV), SDRR (standard deviation of beat-to-beat interval) and RMSSD (root mean square of successive beat-to-beat intervals) were analysed in horses and their riders (n=6 each) at a public performance and an identical rehearsal that was not open to the public. Cortisol concentrations increased in both horses and riders (Phorses and riders increased during the rehearsal and the public performance (Priders than in their horses during the public performance (from 91 ± 10 to 150 ± 15 beats/min) compared to the rehearsal (from 94 ± 10 to 118 ± 12 beats/min). The SDRR decreased significantly during the equestrian tasks in riders (Phorses. The RMSSD decreased in horses and riders (Priders was more pronounced (Priders than it did in their horses.

  16. Uncertainty in model predictions of Vibrio vulnificus response to climate variability and change: a Chesapeake Bay case study.

    Directory of Open Access Journals (Sweden)

    Erin A Urquhart

    Full Text Available The effect that climate change and variability will have on waterborne bacteria is a topic of increasing concern for coastal ecosystems, including the Chesapeake Bay. Surface water temperature trends in the Bay indicate a warming pattern of roughly 0.3-0.4°C per decade over the past 30 years. It is unclear what impact future warming will have on pathogens currently found in the Bay, including Vibrio spp. Using historical environmental data, combined with three different statistical models of Vibrio vulnificus probability, we explore the relationship between environmental change and predicted Vibrio vulnificus presence in the upper Chesapeake Bay. We find that the predicted response of V. vulnificus probability to high temperatures in the Bay differs systematically between models of differing structure. As existing publicly available datasets are inadequate to determine which model structure is most appropriate, the impact of climatic change on the probability of V. vulnificus presence in the Chesapeake Bay remains uncertain. This result points to the challenge of characterizing climate sensitivity of ecological systems in which data are sparse and only statistical models of ecological sensitivity exist.

  17. Biodegradable polymers for electrospinning: towards biomedical applications.

    Science.gov (United States)

    Kai, Dan; Liow, Sing Shy; Loh, Xian Jun

    2014-12-01

    Electrospinning has received much attention recently due to the growing interest in nano-technologies and the unique material properties. This review focuses on recent progress in applying electrospinning technique in production of biodegradable nanofibers to the emerging field of biomedical. It first introduces the basic theory and parameters of nanofibers fabrication, with focus on factors affecting the morphology and fiber diameter of biodegradable nanofibers. Next, commonly electrospun biodegradable nanofibers are discussed, and the comparison of the degradation rate of nanoscale materials with macroscale materials are highlighted. The article also assesses the recent advancement of biodegradable nanofibers in different biomedical applications, including tissue engineering, drug delivery, biosensor and immunoassay. Future perspectives of biodegradable nanofibers are discussed in the last section, which emphasizes on the innovation and development in electrospinning of hydrogels nanofibers, pore size control and scale-up productions.

  18. Biodegradation and toxicological evaluation of lubricant oils

    Directory of Open Access Journals (Sweden)

    Ivo Shodji Tamada

    2012-12-01

    Full Text Available The aim of this work was to compare different toxicity levels of lubricant oils. The tests were performed using the earthworm (Eisenia andrei, arugula seeds (Eruca sativa and lettuce seeds (Lactuca sativa, with three types of contaminants (mineral lubricant oil, synthetic lubricant oil and used lubricant oil for various biodegradation periods in the soil. The toxicity tests indirectly measured the biodegradation of the contaminants. The samples were analyzed at t0, t60, t120 and t180 days of biodegradation. The used lubricant oil was proved very toxic in all the tests and even after biodegradation its toxicity was high. The mineral and synthetic oils were biodegraded efficiently in the soil although their toxicity did not disappear completely after 180 days.

  19. Toluene biodegradation rates in unsaturated soil systems versus liquid batches and their relevance to field conditions

    NARCIS (Netherlands)

    Picone, S.; Grotenhuis, J.T.C.; Gaans, van P.; Valstar, J.; Langenhoff, A.A.M.; Rijnaarts, H.

    2013-01-01

    Contaminant biodegradation in unsaturated soils may reduce the risks of vapor intrusion. However, the reported rates show large variability and are often derived from slurry experiments that are not representative of unsaturated conditions. Here, different laboratory setups are used to derive the bi

  20. Complex resistivity signatures of ethanol biodegradation in porous media

    Science.gov (United States)

    Personna, Yves Robert; Slater, Lee; Ntarlagiannis, Dimitrios; Werkema, Dale; Szabo, Zoltan

    2013-10-01

    Numerous adverse effects are associated with the accidental release of ethanol (EtOH) and its persistence in the subsurface. Geophysical techniques may permit non-invasive, real time monitoring of microbial degradation of hydrocarbon. We performed complex resistivity (CR) measurements in conjunction with geochemical data analysis on three microbial-stimulated and two control columns to investigate changes in electrical properties during EtOH biodegradation processes in porous media. A Debye Decomposition approach was applied to determine the chargeability (m), normalized chargeability (mn) and time constant (τ) of the polarization magnitude and relaxation length scale as a function of time. The CR responses showed a clear distinction between the bioaugmented and control columns in terms of real (σ‧) and imaginary (σ″) conductivity, phase (ϕ) and apparent formation factor (Fapp). Unlike the control columns, a substantial decrease in σ‧ and increase in Fapp occurred at an early time (within 4 days) of the experiment for all three bioaugmented columns. The observed decrease in σ‧ is opposite to previous studies on hydrocarbon biodegradation. These columns also exhibited increases in ϕ (up to ~ 9 mrad) and σ″ (up to two order of magnitude higher) 5 weeks after microbial inoculation. Variations in m and mn were consistent with temporal changes in ϕ and σ″ responses, respectively. Temporal geochemical changes and high resolution scanning electron microscopy imaging corroborated the CR findings, thus indicating the sensitivity of CR measurements to EtOH biodegradation processes. Our results offer insight into the potential application of CR measurements for long-term monitoring of biogeochemical and mineralogical changes during intrinsic and induced EtOH biodegradation in the subsurface.

  1. Opportunities and challenges for the biodegradable magnesium alloys as next-generation biomaterials.

    Science.gov (United States)

    Ding, Wenjiang

    2016-06-01

    In recent years, biodegradable magnesium alloys emerge as a new class of biomaterials for tissue engineering and medical devices. Deploying biodegradable magnesium-based materials not only avoids a second surgical intervention for implant removal but also circumvents the long-term foreign body effect of permanent implants. However, these materials are often subjected to an uncontrolled and fast degradation, acute toxic responses and rapid structural failure presumably due to a localized, too rapid corrosion process. The patented Mg-Nd-Zn-based alloys (JiaoDa BioMg [JDBM]) have been developed in Shanghai Jiao Tong University in recent years. The alloy series exhibit lower biodegradation rate and homogeneous nanophasic degradation patterns as compared with other biodegradable Mg alloys. The in vitro cytotoxicity tests using various types of cells indicate excellent biocompatibility of JDBM. Finally, bone implants using JDBM-1 alloy and cardiovascular stents using JDBM-2 alloy have been successfully fabricated and in vivo long-term assessment via implantation in animal model have been performed. The results confirmed the reduced degradation rate in vivo, excellent tissue compatibility and long-term structural and mechanical durability. Thus, this novel Mg-alloy series with highly uniform nanophasic biodegradation represent a major breakthrough in the field and a promising candidate for manufacturing the next generation biodegradable implants.

  2. Recent advances in biodegradable metals for medical sutures: a critical review.

    Science.gov (United States)

    Seitz, Jan-Marten; Durisin, Martin; Goldman, Jeremy; Drelich, Jaroslaw W

    2015-09-16

    Sutures that biodegrade and dissolve over a period of several weeks are in great demand to stitch wounds and surgical incisions. These new materials are receiving increased acceptance across surgical procedures whenever permanent sutures and long-term care are not needed. Unfortunately, both inflammatory responses and adverse local tissue reactions in the close-to-stitching environment are often reported for biodegradable polymeric sutures currently used by the medical community. While bioabsorbable metals are predominantly investigated and tested for vascular stent or osteosynthesis applications, they also appear to possess adequate bio-compatibility, mechanical properties, and corrosion stability to replace biodegradable polymeric sutures. In this Review, biodegradable alloys made of iron, magnesium, and zinc are critically evaluated as potential materials for the manufacturing of soft and hard tissue sutures. In the case of soft tissue closing and stitching, these metals have to compete against currently available degradable polymers. In the case of hard tissue closing and stitching, biodegradable sternal wires could replace the permanent sutures made of stainless steel or titanium alloys. This Review discusses the specific materials and degradation properties required by all suture materials, summarizes current suture testing protocols and provides a well-grounded direction for the potential future development of biodegradable metal based sutures.

  3. Intra-Individual Response Variability Assessed by Ex-Gaussian Analysis may be a New Endophenotype for Attention-Deficit/Hyperactivity Disorder

    OpenAIRE

    Henríquez-Henríquez, Marcela Patricia; Billeke, Pablo; Henríquez, Hugo; Zamorano, Francisco Javier; ROTHHAMMER, FRANCISCO; Aboitiz, Francisco

    2015-01-01

    Intra-individual variability of response times (RTisv) is considered as potential endophenotype for attentional deficit/hyperactivity disorder (ADHD). Traditional methods for estimating RTisv lose information regarding response times (RTs) distribution along the task, with eventual effects on statistical power. Ex-Gaussian analysis captures the dynamic nature of RTisv, estimating normal and exponential components for RT distribution, with specific phenomenological correlates. Here, we applied...

  4. Intra-individual response variability assessed by ex-gaussian analysis may be a new endophenotype for Attention Deficit / Hyperactivity Disorder

    OpenAIRE

    Marcela Patricia Henríquez-Henríquez; Pablo eBilleke; Hugo eHenríquez; Francisco Javier Zamorano; Francisco eRothhammer; Francisco eAboitiz

    2015-01-01

    Intra-individual variability of Response Times (RTisv) is considered as potential endophenotype for Attentional Deficit/Hyperactivity Disorder (ADHD). Traditional methods for estimating RTisv lose information regarding Response Times (RTs) distribution along the task, with eventual effects on statistical power. Ex-Gaussian analysis captures the dynamic nature of RTisv, estimating normal and exponential components for RT distribution, with specific phenomenological correlates. Here, we applie...

  5. Intimately coupling of photolysis accelerates nitrobenzene biodegradation, but sequential coupling slows biodegradation

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Lihui [Department of Environmental Science and Engineering, College of Life and Environmental Science, Shanghai Normal University, Shanghai 200234 (China); Zhang, Yongming, E-mail: zhym@shnu.edu.cn [Department of Environmental Science and Engineering, College of Life and Environmental Science, Shanghai Normal University, Shanghai 200234 (China); Bai, Qi; Yan, Ning; Xu, Hua [Department of Environmental Science and Engineering, College of Life and Environmental Science, Shanghai Normal University, Shanghai 200234 (China); Rittmann, Bruce E. [Swette Center for Environmental Biotechnology, Biodesign Institute, Arizona State University, Tempe, AZ 85287-5701 (United States)

    2015-04-28

    Highlights: • Intimately coupled UV photolysis accelerated nitrobenzene biodegradation. • NB biodegradation was slowed by accumulation of nitrophenol. • Oxalic acid was a key product of UV photolysis. • Oxalic acid accelerated biodegradation of nitrobenzene and nitrophenol by a co-substrate effect. • Intimate coupling of UV and biodegradation accentuated the benefits of oxalic acid. - Abstract: Photo(cata)lysis coupled with biodegradation is superior to photo(cata)lysis or biodegradation alone for removal of recalcitrant organic compounds. The two steps can be carried out sequentially or simultaneously via intimate coupling. We studied nitrobenzene (NB) removal and mineralization to evaluate why intimate coupling of photolysis with biodegradation was superior to sequential coupling. Employing an internal circulation baffled biofilm reactor, we compared direct biodegradation (B), biodegradation after photolysis (P + B), simultaneous photolysis and biodegradation (P&B), and biodegradation with nitrophenol (NP) and oxalic acid (OA) added individually and simultaneously (B + NP, B + OA, and B + NP + OA); NP and OA were NB’s main UV-photolysis products. Compared with B, the biodegradation rate P + B was lower by 13–29%, but intimately coupling (P&B) had a removal rate that was 10–13% higher; mineralization showed similar trends. B + OA gave results similar to P&B, B + NP gave results similar to P + B, and B + OA + NP gave results between P + B and P&B, depending on the amount of OA and NP added. The photolysis product OA accelerated NB biodegradation through a co-substrate effect, but NP was inhibitory. Although decreasing the UV photolysis time could minimize the inhibition impact of NP in P + B, P&B gave the fastest removal of NB by accentuating the co-substrate effect of OA.

  6. Time- and frequency-domain parameters of heart rate variability and sympathetic skin response in Parkinson's disease.

    Science.gov (United States)

    Maetzler, Walter; Karam, Marie; Berger, Monika Fruhmann; Heger, Tanja; Maetzler, Corina; Ruediger, Heinz; Bronzova, Juliana; Lobo, Patricia Pita; Ferreira, Joaquim J; Ziemssen, Tjalf; Berg, Daniela

    2015-03-01

    The autonomic nervous system (ANS) is regularly affected in Parkinson's disease (PD). Information on autonomic dysfunction can be derived from e.g. altered heart rate variability (HRV) and sympathetic skin response (SSR). Such parameters can be quantified easily and measured repeatedly which might be helpful for evaluating disease progression and therapeutic outcome. In this 2-center study, HRV and SSR of 45 PD patients and 26 controls were recorded. HRV was measured during supine metronomic breathing and analyzed in time- and frequency-domains. SSR was evoked by repetitive auditory stimulation. Various ANS parameters were compared (1) between patients and healthy controls, (2) to clinical scales (Unified Parkinson's disease rating scale, Mini-Mental State Examination, Becks Depression Inventory), and (3) to disease duration. Root mean square of successive differences (RMSSD) and low frequency/high frequency (LF/HF) ratio differed significantly between PD and controls. Both, HRV and SSR parameters showed low or no association with clinical scores. Time-domain parameters tended to be affected already at early PD stages but did not consistently change with longer disease duration. In contrast, frequency-domain parameters were not altered in early PD phases but tended to be lower (LF, LF/HF ratio), respectively higher (HF) with increasing disease duration. This report confirms previous results of altered ANS parameters in PD. In addition, it suggests that (1) these ANS parameters are not relevantly associated with motor, behavioral, and cognitive changes in PD, (2) time-domain parameters are useful for the assessment of early PD, and (3) frequency-domain parameters are more closely associated with disease duration.

  7. Low Power-Consumption and High Response Frequency Thermo-Optic Variable Optical Attenuators Based on Silicon-on-Insulator Materials

    Institute of Scientific and Technical Information of China (English)

    FANG Qing; CHEN Peng; XIN Hong-Li; WANG Chun-Xia; LI Fang; LIU Yu-Liang

    2005-01-01

    @@ A novel silicon-on-insulator thermo-optic variable optical attenuator with isolated grooves based on a multimode interference coupler principle is fabricated by the inductive coupled plasma etching technology. The maximum fibre-to-fibre insertion loss is lower than 2.2 dB, the dynamic attenuation range is from 0 to 30 dB in the wavelength range 1500-1600nm, and the maximum power consumption is only 140mW. The response frequency of the fabricated variable optical attenuator is about 30 kHz. Compared to the variable optical attenuator without isolated grooves, the maximum power consumption decreases more than 220mW, and the response frequency rises are more than 20kHz.

  8. The usefulness of the Basic Question Procedure for determining non-response bias in substantive variables - A test of four telephone questionnaires

    NARCIS (Netherlands)

    van Goor, Henk; van Goor, Annemiek

    2007-01-01

    The Basic Question Procedure (BQP) is a method for determining non-response bias. The BQP involves asking one basic question - that is, the question relating to the central substantive variable of the study - of those persons who refuse to participate in the survey. We studied the usefulness of this

  9. Breaking down the coercive cycle: How parent and child risk factors influence real-time variability in parental responses to child misbehavior

    NARCIS (Netherlands)

    Lunkenheimer, E.S.; Lichtwarck-Aschoff, A.; Hollenstein, T.P.; Kemp, C.J.; Granic, I.

    2016-01-01

    Objective. Parent-child coercive cycles have been associated with both rigidity and inconsistency in parenting behavior. To explain these mixed findings, we examined real-time variability in maternal responses to children’s off-task behavior to determine whether this common trigger of the coercive c

  10. Biodegradation of PuEDTA and Impacts on Pu Mobility

    Energy Technology Data Exchange (ETDEWEB)

    Bolton, H., Jr.; Rai, D.; Xun, L.

    2004-03-17

    The contamination of many DOE sites by Pu presents a long-term problem because of its long half-life (240,000 yrs) and the low drinking water standard (<10{sup -12} M). EDTA was co-disposed with radionuclides (e.g., Pu, {sup 60}Co), formed strong complexes, and enhanced radionuclide transport at several DOE sites. Biodegradation of EDTA should decrease Pu mobility. One objective of this project was to determine the biodegradation of EDTA in the presence of PuEDTA complexes. The aqueous system investigated at pH 7 (10{sup -4} M EDTA and 10{sup -6} M Pu) contained predominantly Pu(OH){sub 2}EDTA{sup 2-}. The EDTA was degraded at a faster rate in the presence of Pu. As the total concentration of both EDTA and PuEDTA decreased (i.e., 10{sup -5} M EDTA and 10{sup -7} M PuEDTA), the presence of Pu decreased the biodegradation rate of the EDTA. It is currently unclear why the concentration of Pu directly affects the increase/decrease in rate of EDTA biodegradation. The soluble Pu concentration decreased, in agreement with thermodynamic predictions, as the EDTA was biodegraded, indicating that biodegradation of EDTA will decrease Pu mobility when the Pu is initially present as Pu(IV)EDTA. A second objective was to investigate how the presence of competing metals, commonly encountered in geologic media, will influence the speciation and biodegradation of Pu(IV)-EDTA. Studies on the solubilities of Fe(OH){sub 3}(s) and of Fe(OH){sub 3}(s) plus PuO{sub 2}(am) in the presence of EDTA and as a function of pH showed that Fe(III) out competes the Pu(IV) for the EDTA complex, thereby showing that Pu(IV) will not form stable complexes with EDTA for enhanced transport of Pu in Fe(III) dominated subsurface systems. A third objective is to investigate the genes and enzymes involved in EDTA biodegradation. BNC1 can use EDTA and another synthetic chelating agent nitrilotriacetate (NTA) as sole carbon and nitrogen sources. The same catabolic enzymes are responsible for both EDTA and NTA

  11. Evaluating the Impact of Contaminant Dilution and Biodegradation in Uncertainty Quantification of Human Health Risk

    Science.gov (United States)

    Zarlenga, Antonio; de Barros, Felipe; Fiori, Aldo

    2016-04-01

    We present a probabilistic framework for assessing human health risk due to groundwater contamination. Our goal is to quantify how physical hydrogeological and biochemical parameters control the magnitude and uncertainty of human health risk. Our methodology captures the whole risk chain from the aquifer contamination to the tap water assumption by human population. The contaminant concentration, the key parameter for the risk estimation, is governed by the interplay between the large-scale advection, caused by heterogeneity and the degradation processes strictly related to the local scale dispersion processes. The core of the hazard identification and of the methodology is the reactive transport model: erratic displacement of contaminant in groundwater, due to the spatial variability of hydraulic conductivity (K), is characterized by a first-order Lagrangian stochastic model; different dynamics are considered as possible ways of biodegradation in aerobic and anaerobic conditions. With the goal of quantifying uncertainty, the Beta distribution is assumed for the concentration probability density function (pdf) model, while different levels of approximation are explored for the estimation of the one-point concentration moments. The information pertaining the flow and transport is connected with a proper dose response assessment which generally involves the estimation of physiological parameters of the exposed population. Human health response depends on the exposed individual metabolism (e.g. variability) and is subject to uncertainty. Therefore, the health parameters are intrinsically a stochastic. As a consequence, we provide an integrated in a global probabilistic human health risk framework which allows the propagation of the uncertainty from multiple sources. The final result, the health risk pdf, is expressed as function of a few relevant, physically-based parameters such as the size of the injection area, the Péclet number, the K structure metrics and

  12. Biodegradable and compostable alternatives to conventional plastics.

    Science.gov (United States)

    Song, J H; Murphy, R J; Narayan, R; Davies, G B H

    2009-07-27

    Packaging waste forms a significant part of municipal solid waste and has caused increasing environmental concerns, resulting in a strengthening of various regulations aimed at reducing the amounts generated. Among other materials, a wide range of oil-based polymers is currently used in packaging applications. These are virtually all non-biodegradable, and some are difficult to recycle or reuse due to being complex composites having varying levels of contamination. Recently, significant progress has been made in the development of biodegradable plastics, largely from renewable natural resources, to produce biodegradable materials with similar functionality to that of oil-based polymers. The expansion in these bio-based materials has several potential benefits for greenhouse gas balances and other environmental impacts over whole life cycles and in the use of renewable, rather than finite resources. It is intended that use of biodegradable materials will contribute to sustainability and reduction in the environmental impact associated with disposal of oil-based polymers. The diversity of biodegradable materials and their varying properties makes it difficult to make simple, generic assessments such as biodegradable products are all 'good' or petrochemical-based products are all 'bad'. This paper discusses the potential impacts of biodegradable packaging materials and their waste management, particularly via composting. It presents the key issues that inform judgements of the benefits these materials have in relation to conventional, petrochemical-based counterparts. Specific examples are given from new research on biodegradability in simulated 'home' composting systems. It is the view of the authors that biodegradable packaging materials are most suitable for single-use disposable applications where the post-consumer waste can be locally composted.

  13. ALTERNATIVE FOR PHENOL BIODEGRADATION IN OIL CONTAMINATED WASTEWATERS USING AN ADAPTED BACTERIAL BIOFILM LAYER

    Directory of Open Access Journals (Sweden)

    Maria Kopytko

    2008-12-01

    Full Text Available The project studied the biodegradation potential of phenols in an industrial wastewater from an oil field in the province of Santander, Colombia. An elevated potential was established, according to three important factors: the great abundance of microorganisms found in the wastewater and sludge samples collected, the bacterial adaptation to high phenol concentrations (10 mg/l and the elevated elimination efficiencies (up to 86% obtained in the laboratory tests. The laboratory scale treatment system, which consisted of fixed-bed bioreactors with adapted bacterial biofilm, was optimized using a 22 factorial experimental design. The selected variables, studied in their maximum and minimum level were: HRT (hydraulic retention time and the presence or absence of GAC (granular activated carbon layer. The response variable was phenol concentration. The optimum treatment conditions for low and high phenol concentrations (2.14 y 9.30 mg/l, were obtained with the presence of GAC and 18 hours of HRT. The best result for the intermediate phenol concentration (6.13 mg/l was obtained with a 24 hour HRT and the presence of GAC. Nevertheless, the presence of the GAC layer was not significantly important in terms of phenol removal. Moreover, the increase of HRT from 18 to 24 hours, showed no significant improvement in phenol removal.

  14. Biodegradable Metals From Concept to Applications

    CERN Document Server

    Hermawan, Hendra

    2012-01-01

    This book in the emerging research field of biomaterials covers biodegradable metals for biomedical applications. The book contains two main parts where each of them consists of three chapters. The first part introduces the readers to the field of metallic biomaterials, exposes the state of the art of biodegradable metals, and reveals its application for cardiovascular implants. It includes some fundamental aspects to give basic understanding on metals for further review on the degradable ones is covered in chapter one. The second chapter introduces the concept of biodegradable metals, it's st

  15. Preparation and degradation mechanisms of biodegradable polymer: a review

    Science.gov (United States)

    Zeng, S. H.; Duan, P. P.; Shen, M. X.; Xue, Y. J.; Wang, Z. Y.

    2016-07-01

    Polymers are difficult to degrade completely in Nature, and their catabolites may pollute the environment. In recent years, biodegradable polymers have become the hot topic in people's daily life with increasing interest, and a controllable polymer biodegradation is one of the most important directions for future polymer science. This article presents the main preparation methods for biodegradable polymers and discusses their degradation mechanisms, the biodegradable factors, recent researches and their applications. The future researches of biodegradable polymers are also put forward.

  16. Biodegradation of petroleum products in experimental plots in Antarctic marine sediments is location dependent.

    Science.gov (United States)

    Powell, Shane M; Harvey, Paul McA; Stark, Jonathan S; Snape, Ian; Riddle, Martin J

    2007-04-01

    Clean sediment collected from O'Brien Bay, East Antarctica, was artificially contaminated with a mix of Special Antarctic Blend diesel fuel and lubricating oil and deployed in two uncontaminated locations (O'Brien and Sparkes Bays) and a previously contaminated bay (Brown Bay) to evaluate whether a history of prior contamination would influence the biodegradation process. Detailed analysis of the hydrocarbon composition in the sediment after 11 weeks revealed different patterns of degradation in each bay. Biodegradation indices showed that hydrocarbon biodegradation occurred in all three bays but was most extensive in Brown Bay. This study shows that even within a relatively small geographical area, the longevity of hydrocarbons in Antarctic marine sediments can be variable. Our results are consistent with faster natural attenuation of spilt oil at sites with previous exposure to oil but further work is needed to confirm this. Such information would be useful when evaluating the true risk and longevity of oils spills.

  17. Engineered biosynthesis of biodegradable polymers.

    Science.gov (United States)

    Jambunathan, Pooja; Zhang, Kechun

    2016-08-01

    Advances in science and technology have resulted in the rapid development of biobased plastics and the major drivers for this expansion are rising environmental concerns of plastic pollution and the depletion of fossil-fuels. This paper presents a broad view on the recent developments of three promising biobased plastics, polylactic acid (PLA), polyhydroxyalkanoate (PHA) and polybutylene succinate (PBS), well known for their biodegradability. The article discusses the natural and recombinant host organisms used for fermentative production of monomers, alternative carbon feedstocks that have been used to lower production cost, different metabolic engineering strategies used to improve product titers, various fermentation technologies employed to increase productivities and finally, the different downstream processes used for recovery and purification of the monomers and polymers.

  18. Lubricant Biodegradation Enhancers:Designed Chemistry and Engineered Technology

    Institute of Scientific and Technical Information of China (English)

    Chen Boshui; Gao Lingyue; Fang Jianhua; Zhang Nan; Wu Jiang; Wang Jiu

    2015-01-01

    In recent decades, a growing worldwide trend of developing the biodegradable lubricants has been prevailing to form a speciifc ifeld of green chemistry and green engineering. Enhancement of biodegradability of unreadily biodegradable petroleum-based lubricants has as such become an urgent must. For over a decade the authors have been focusing on the im-provement of biodegradability of unreadily biodegradable lubricants such as petroleum-based lubricating oils and greases. A new idea of lubricant biodegradation enhancer was put forward by the authors with the aim to stimulate the biodegradation of unreadily biodegradable lubricants by incorporating the enhancer into the lubricants in order to turn the lubricants into greener biodegradable ones and to help in situ bioremediation of lubricant-contaminated environment. This manuscript sum-marizes our recent efforts relating to the chemistry and technology of biodegradation enhancers for lubricants. Firstly, the chemistry of lubricant biodegradation enhancers was designed based on the principles of bioremediation for the treatment of hydrocarbon contaminated environment. Secondly, the ability of the designed biodegradation enhancers for increasing the biodegradability of unreadily biodegradable industrial lubricants was investigated through biodegradability evaluation tests, microbial population analysis, and biodegradation kinetics modeling. Finally, the impact of biodegradation enhancers on some crucial performance characteristics of lubricants such as lubricity and oxidation stability was tested via tribological evaluation and oxidation determinations. Our results have shown that the designed chemistry of nitrogenous and/or phos-phorous compounds such as lauroyl glutamine, oleoyl glycine, oleic diethanolamide phosphate and lauric diethanolamide borate was outstanding in boosting biodegradation of petroleum-based lubricants which was ascribed to increase the micro-bial population and decrease the oil-water interfacial

  19. SIFAT MEKANIK DAN MORFOLOGI PLASTIK BIODEGRADABLE DARI LIMBAH TEPUNG NASI AKING DAN TEPUNG TAPIOKA MENGGUNAKAN PEMLASTIK GLISEROL

    OpenAIRE

    Andri Cahyo Kumoro; Aprilina Purbasari

    2014-01-01

    [Title: Mechanical Properties and Morfology of Biodegradable Plastic from Steamed Rice Waste and Cassava Flour with Glycerol as Plasticizer] The annual consumption of plastic packaging has increased significantly as a response to the increase of people’s need and buying power. As a packaging material, plastic is light, flexible, practical and inexpensive. Unfortunately, if the plastic is not biodegradable and dumped irresponsibly to the ecosystem may cause serious environmental problems. The...

  20. Transport of nonlinearly biodegradable contaminants in aquifers

    OpenAIRE

    Keijzer, H.

    2001-01-01

    This thesis deals with the transport behavior of nonlinearly biodegradable contaminants in aquifers. Such transport occurs during in situ bioremediation which is based on the injection of an electron acceptor or electron donor. The main interests in this thesis are the mutual influences of underlying processes, i.e. transport, adsorption and biodegradation, and their influence on in situ bioremediation performance. To gain insight in these influences, the processes in a homogeneous aquifer ar...

  1. Ball Powder Production Wastewater Biodegradation Support Studies

    Science.gov (United States)

    1989-02-01

    Any unusual removal criteria (NO3, toxic compound, etc.): * None 9 Type of wastewater treated: Dairy ( whey and grease) 1 Design basis for scale-up... WASTEWATER BIODEGRADATION SUPPORT STUDIES (TASK ORDER NO. 11) February 1989 Contract No. DAAK11-85-D-0008 w MAR 2 9 1983 Prepared by: Arthur D...United States Army Toxic and Hazardous Materials Agency February 1989 I Ball Powder Production Wastewater Pilot-Scale £ Biodegradation Support Studies I

  2. Biodegradability of Chlorinated Anilines in Waters

    Institute of Scientific and Technical Information of China (English)

    CHAO WANG; GUAN-GHUA LU; YAN-JIE ZHOU

    2007-01-01

    Objective To identify the bacteria tolerating chlorinated anilines and to study the biodegradability of o-chloroaniline and its coexistent compounds. Methods Microbial community of complex bacteria was identified by plate culture observation techniques and Gram stain method. Bacterial growth inhibition test was used to determine the tolerance of complex bacteria to toxicant. Biodegradability of chlorinated anilines was determined using domesticated complex bacteria as an inoculum by shaking-flask test. Results The complex bacteria were identified, consisting of Xanthomonas, Bacillus alcaligenes,Acinetobacter, Pseudomonas, and Actinomycetaceae nocardia. The obtained complex bacteria were more tolerant to o-chloroaniline than mixture bacteria in natural river waters. The effects of exposure concentration and inoculum size on the biodegradability of o-chloroaniline were analyzed, and the biodegradation characteristics of single o-chloroaniline and 2,4-dichloroaniline were compared with the coexistent compounds. Conclusion The biodegradation rates can be improved by decreasing concentration of compounds and increasing inoculum size of complex bacteria. When o-chloroaniline coexists with aniline, the latter is biodegraded prior to the former, and as a consequence the metabolic efficiency of o-chloroaniline is improved with the increase of aniline concentration. Meanwhile, when o-chloroaniline coexists with 2,4-dichloroaniline, the metabolic efficiency of 2,4-dichloroaniline is markedly improved.

  3. Immersed multilayer biodegradable ureteral stent with reformed biodegradation: An in vitro experiment.

    Science.gov (United States)

    Yang, Ganggang; Xie, Hua; Huang, Yichen; Lv, Yiqing; Zhang, Mingqing; Shang, Yafeng; Zhou, Junmei; Wang, Liping; Wang, Jin-Ye; Chen, Fang

    2017-03-01

    Objective The aim of this study was to develop a novel immersed multilayer biodegradable ureteral stent with reformed biodegradation and evaluate it in vitro. Methods Poly(glycolic-co-lactic acid) (PGLA), microsphere zein and BaSO4 were employed to produce a multilayer biodegradable stent using immersion technology. Tests of the biodegradable stents and conventional control stents were conducted in human urine in vitro to evaluate the biodegradable properties. The biocompatibility was assessed by the morphology and proliferation of urine-derived cells cultured with extracted media from the biodegradable stent and a latex material positive control. Results An immersed multilayer biodegradable stent was successfully produced. It began to degrade in week 2 and was fully degraded by week 4. The mass loss ratio in the first 2 weeks was low (approximately 10.0% at 1 week, 20.0% at 2 weeks) and increased after 3 weeks (approximately 70%) to the end of testing. During the first 2 weeks, the radial compression load performances of the biodegradable stents were better than those of the control stents with statistically significant differences ( p = 0.00, p = 0.01) and the tensile strengths were lower in the biodegradable stents than those in the control stents throughout the experiment. SEM showed that the stents degraded layer by layer from the outer to the inner wall. The influences on the cells of extracted medium from the biodegradable stents were morphologically slight and lower than 10% in relative growth rates. Conclusions This preliminary study demonstrates that the immersed multilayer biodegradable ureteral stent has good radial compression and biocompatible performance and can be degraded in vitro within 4 weeks in a moderate manner.

  4. Millennial-scale climate variability in response to changing glacial and orbital boundary conditions during the Mid-Pleistocene transition

    Science.gov (United States)

    Ferretti, Patrizia; Crowhurst, Simon; Drysdale, Russell; Bajo, Petra; Barbante, Carlo

    2016-04-01

    The Mid-Pleistocene transition represents perhaps the most important climate transition in the Quaternary period, yet it is one of the most poorly understood. Although the exact timing and mechanism of the onset of the "100 kyr" regime remain a matter of debate, it is well established that the overall periodicity of the glacial-interglacial cycles changed from a dominant 41 kyr obliquity periodicity prior to ~0.9 Ma to a dominant late Pleistocene 100 kyr variance. This change in the frequency domain was associated with an increase in the amplitude of global ice volume variations that, superimposed on a long-term climatic trend towards more glacial conditions over millions of years, produced some of the most extreme glaciations recorded. This interval of time has often been considered to be important in relation to long-term Milankovitch-scale climate variability. In contrast, here, special emphasis will be placed on assessing the presence and the characteristics of the suborbital-scale variability, and reconstructing the evolution of millennial-scale climate variability as the average climate state evolve toward generally colder conditions with larger ice sheets, and the spectral character of climate variability shifted from dominantly 41 kyr to 100 kyr. Appealing evidence suggests that millennial-scale climate variability is amplified during times of intense forcing changes, but this rapid variability has not been thoroughly explored yet at the time when the major changes in climate periodicity occurred. To address these questions, we have examined the record of climatic conditions from Marine Isotope Stages 25 to 16 (~970-650 ka) using high-resolution stable isotope records from benthic and planktonic foraminifera from a sedimentary sequence in the North Atlantic (Integrated Ocean Drilling Program Expedition 306, Site U1313) in order to assess millennial-scale changes in sea-surface and deep-water conditions, the dynamics of thermohaline deep-water circulation

  5. Instrumental variables estimation of exposure effects on a time-to-event response using structural cumulative survival models

    DEFF Research Database (Denmark)

    Martinussen, T.; Vansteelandt, S.; Tchetgen, E. J. Tchetgen;

    2016-01-01

    of complications due to censoring and survivorship bias. In this paper, we make a novel proposal under a class of structural cumulative survival models which parameterize time-varying effects of a point exposure directly on the scale of the survival function; these models are essentially equivalent with a semi......-parametric variant of the instrumental variables additive hazards model. We propose a class of recursive instrumental variable estimators for these exposure effects, and derive their large sample properties along with inferential tools. We examine the performance of the proposed method in simulation studies...

  6. Microbial life in continental salt pan sediments and their response to climate variability in Northern South Africa

    Science.gov (United States)

    Genderjahn, Steffi; Mangelsdorf, Kai; Alawi, Mashal; Belz, Lukas; Kallmeyer, Jens; Wagner, Dirk

    2016-04-01

    The environmental history of southwestern African mainland is largely unknown. Since there are no lacustrine systems with constant water coverage in this area, we investigated a continental salt pan as a terrestrial geoarchive with the potential to preserve climate signals. Within the frame of the research project "GeoArchives" (part of the SPACES program, funded by the German Federal Ministry of Education and Research, BMBF) we aimed to reconstruct climate variabilities during the late Pleistocene to Holocene. The presented study is focused on variations within the microbial community structure and abundance of key organisms in a salt pan with special regards to sediment age and geochemical parameters. A combined approach of a 16S rDNA-based quantification method and lipid biomarker analysis was used to demonstrate the response of the microbial communities with respect to environmental changes. The phospholipid derived fatty acids (PLFAs) in sedimentary deposits are characteristic markers for living Bacteria, whereby their side chain represents a fingerprint of the community structure on a broad taxonomic level. Archaeol and isoprenoid glycerol dialkyl glycerol tetraethers (iGDGTs) were used as characteristic makers for Archaea whereas branched GDGTs (brGDGTs) are typical biomarkers for Bacteria. In contrast to PLFAs, they represent dead microbial biomass and thus the past microbial communities in older sediments, since they are already partly degraded. Samples from the Witpan, located in the northwest of South Africa and representing a depths profile from the Late Pleistocene to Holocene, were gathered. Despite the extreme environment with rather low TOC values, restricted availability of water and high salt concentration markers for Bacteria and Archaea were observed. A series of saturated, branched and unsaturated PLFAs were identified. The diversity and concentration of PLFAs were highest in the top layers (up to 30000 ng gsed-1, 0-10 cm) and characteristic

  7. Design of biodegradable particles for protein delivery.

    Science.gov (United States)

    Vila, A; Sánchez, A; Tobío, M; Calvo, P; Alonso, M J

    2002-01-17

    Major research issues in protein delivery include the stabilization of proteins in delivery devices and the design of appropriate protein carriers in order to overcome mucosal barriers. We have attempted to combine both issues through the conception of new biodegradable polymer nanoparticles: (i) poly(ethylene glycol) (PEG)-coated poly(lactic acid) (PLA) nanoparticles, chitosan (CS)-coated poly(lactic acid-glycolic acid (PLGA) nanoparticles and chitosan (CS) nanoparticles. These nanoparticles have been tested for their ability to load proteins, to deliver them in an active form, and to transport them across the nasal and intestinal mucosae. Additionally, the stability of some of these nanoparticles in simulated physiological fluids has been studied. Results showed that the PEG coating improves the stability of PLA nanoparticles in the gastrointestinal fluids and helps the transport of the encapsulated protein, tetanus toxoid, across the intestinal and nasal mucosae. Furthermore, intranasal administration of these nanoparticles provided high and long-lasting immune responses. On the other hand, the coating of PLGA nanoparticles with the mucoadhesive polymer CS improved the stability of the particles in the presence of lysozyme and enhanced the nasal transport of the encapsulated tetanus toxoid. Finally, nanoparticles made solely of CS were also stable upon incubation with lysozyme. Moreover, these particles were very efficient in improving the nasal absorption of insulin as well as the local and systemic immune responses to tetanus toxoid, following intranasal administration. In summary, these results show that a rational modification in the composition and structure of the nanoparticles, using safe materials, increases the prospects of their usefulness for mucosal protein delivery and transport.

  8. Lower white matter microstructure in the superior longitudinal fasciculus is associated with increased response time variability in adults with attention-deficit/ hyperactivity disorder

    OpenAIRE

    Wolfers, T.; Onnink, A.M.; Zwiers, M.P.; Arias Vasquez, A.; Hoogman, M.; Mostert, J.C.; Kan, C C; Slaats-Willemse, D.I.E.; Buitelaar, J.; Franke, B

    2015-01-01

    BACKGROUND: Response time variability (RTV) is consistently increased in patients with attention-deficit/hyperactivity disorder (ADHD). A right-hemispheric frontoparietal attention network model has been implicated in these patients. The 3 main connecting fibre tracts in this network, the superior longitudinal fasciculus (SLF), inferior longitudinal fasciculus (ILF) and the cingulum bundle (CB), show microstructural abnormalities in patients with ADHD. We hypothesized that the microstructural...

  9. Resilience, rapid transitions and regime shifts: fingerprinting the responses of Lake Żabińskie (NE Poland) to climate variability and human disturbance since 1000 AD

    Science.gov (United States)

    Tylmann, Wojciech; Hernández-Almeida, Iván; Grosjean, Martin; José Gómez Navarro, Juan; Larocque-Tobler, Isabelle; Bonk, Alicja; Enters, Dirk; Ustrzycka, Alicja; Piotrowska, Natalia; Przybylak, Rajmund; Wacnik, Agnieszka; Witak, Małgorzata

    2016-04-01

    Rapid ecosystem transitions and adverse effects on ecosystem services as responses to combined climate and human impacts are of major concern. Yet few quantitative observational data exist, particularly for ecosystems that have a long history of human intervention. Here, we combine quantitative summer and winter climate reconstructions, climate model simulations and proxies for three major environmental pressures (land use, nutrients and erosion) to explore the system dynamics, resilience, and the role of disturbance regimes in varved eutrophic Lake Żabińskie since AD 1000. Comparison between regional and global climate simulations and quantitative climate reconstructions indicate that proxy data capture noticeably natural forced climate variability, while internal variability appears as the dominant source of climate variability in the climate model simulations during most parts of the last millennium. Using different multivariate analyses and change point detection techniques, we identify ecosystem changes through time and shifts between rather stable states and highly variable ones, as expressed by the proxies for land-use, erosion and productivity in the lake. Prior to AD 1600, the lake ecosystem was characterized by a high stability and resilience against considerable observed natural climate variability. In contrast, lake-ecosystem conditions started to fluctuate at high frequency across a broad range of states after AD 1600. The period AD 1748-1868 represents the phase with the strongest human disturbance of the ecosystem. Analyses of the frequency of change points in the multi-proxy dataset suggests that the last 400 years were highly variable and flickering with increasing vulnerability of the ecosystem to the combined effects of climate variability and anthropogenic disturbances. This led to significant rapid ecosystem transformations.

  10. Decreasing precipitation variability does not elicit major aboveground biomass or plant diversity responses in a mesic rangeland

    Science.gov (United States)

    There is an emergent need to understand how altered precipitation regimes will affect aboveground biomass, stability of this biomass, and diversity in grassland ecosystems. We used replicated 9X10 m rainout shelters to experimentally remove inherent intra- and inter-annual variability of precipitati...

  11. The Role of Early Symptom Trajectories and Pretreatment Variables in Predicting Treatment Response to Cognitive Behavioral Therapy

    Science.gov (United States)

    Lewis, Cara C.; Simons, Anne D.; Kim, Hyoun K.

    2012-01-01

    Objective: Research has focused on 2 different approaches to answering the question, "Which clients will respond to cognitive behavioral therapy (CBT) for depression?" One approach focuses on rates of symptom change within the 1st few weeks of treatment, whereas the 2nd approach looks to pretreatment client variables (e.g., hopelessness) to…

  12. Rapid biodegradation of polycyclic aromatic hydrocarbons (PAHs) using effective Cronobacter sakazakii MM045 (KT933253).

    Science.gov (United States)

    Umar, Zubairu Darma; Aziz, Nor Azwady Abd; Zulkifli, Syaizwan Zahmir; Mustafa, Muskhazli

    2017-01-01

    Polycyclic Aromatic Hydrocarbons (PAHs) are complex and widely distributed environmental pollutants that can affect living ecosystems. This study was conducted to rapidly degrade phenanthrene and pyrene representing low and high molecular weight of PAHs, respectively. Cronobacter sakazakii MM045 (KT933253) was identified from used engine oil of contaminated soil. PAHs biodegradation was carried out using 2,6-dichlorophenol indophenol (DCPIP) assay. Biodegradation influencing factors including agitation, temperature, pH, inoculums volume and salinity were enhanced using Response Surface Methodology (RSM) by Central Composite Design (CCD). Phenanthrene and pyrene biodegrading metabolites were identified using gas chromatography mass spectrophotometer (GCMS). •Initial biodegradation indicated 75.2% and 54.3% phenanthrene and pyrene degraded by C. sakazakii MM045 within 24 h. After CCD optimisation, 100% degradation was achieved for each of the phenanthrene and pyrene, resulting in the formation of intermediate metabolites.•The identified phenanthrene metabolites were 3,4-dihydroxyphenathrene, phthalic acid, pyruvic acid, acetic acid and oxalic acid. Pyrene intermediates comprised pyrene cis-4,5-dihydrodiol, 3,4-dihydroxyphenanthrene, phthalic acid, pyruvic acid, acetic acid and lactic acid.•Cronbacter sakazakii MM045 was proven to be rapid and effective in degrading PAHs within 24 h despite the unavailability of existing literatures on PAHs biodegradation.

  13. Biomechanical Challenges to Polymeric Biodegradable Stents.

    Science.gov (United States)

    Soares, Joao S; Moore, James E

    2016-02-01

    Biodegradable implants have demonstrated clinical success in simple applications (e.g., absorbable sutures) and have shown great potential in many other areas of interventional medicine, such as localized drug delivery, engineered tissue scaffolding, and structural implants. For endovascular stenting and musculoskeletal applications, they can serve as temporary mechanical support that provides a smooth stress-transfer from the degradable implant to the healing tissue. However, for more complex device geometries, in vivo environments, and evolving load-bearing functions, such as required for vascular stents, there are considerable challenges associated with the use of biodegradable materials. A biodegradable stent must restore blood flow and provide support for a predictable appropriate period to facilitate artery healing, and subsequently, fail safely and be absorbed in a controllable manner. Biodegradable polymers are typically weaker than metals currently employed to construct stents, so it is difficult to ensure sufficient strength to keep the artery open and alleviate symptoms acutely while keeping other design parameters within clinically acceptable ranges. These design challenges are serious, given the general lack of understanding of biodegradable polymer behavior and evolution in intimal operating conditions. The modus operandi is mainly empirical and relies heavily on trial-and-error methodologies burdened by difficult, resource-expensive, and time-consuming experiments. We are striving for theoretical advancements systematizing the empirical knowledge into rational frameworks that could be cast into in silico tools for simulation and product development optimization. These challenges are evident when one considers that there are no biodegradable stents on the US market despite more than 30 years of development efforts (and currently only a couple with CE mark). This review summarizes previous efforts at implementing biodegradable stents, discusses the

  14. Preferential biodegradation of structurally dissimilar dyes from a mixture by Brevibacillus laterosporus.

    Science.gov (United States)

    Kurade, Mayur B; Waghmode, Tatoba R; Govindwar, Sanjay P

    2011-09-15

    Biodegradation of a mixture containing seven commercial textile dyes with different structures and color properties has been investigated by an ecofriendly strain--Brevibacillus laterosporus MTCC 2298. It showed 87% decolorization in terms of ADMI removal (American Dye Manufacturing Institute) within 24h. The effective decolorization of dye mixture was attained in the presence of metal salt--CaCl(2) and nitrogen sources. The induction of oxido-reductive enzymes such as veratryl alcohol oxidase, tyrosinase, NADH-DCIP reductase and azo reductase was found to be responsible for biotransformation of dyes. High performance thin layer chromatography exposed the mechanism of preferential biodegradation of dyes at different time periods. Significant change in the high pressure liquid chromatography and Fourier transform infrared spectroscopy of sample before and after treatment confirmed the biodegradation of dye mixture. Phytotoxicity study revealed the much less toxic nature of the metabolites produced after the degradation of dyes mixture.

  15. Toxicity and biodegradability of olive mill wastewaters in batch anaerobic digestion

    Energy Technology Data Exchange (ETDEWEB)

    Hamdi, M. (Centre de Biotechnologie, Sfax (Tunisia) Universite de Provence, Marseille (France))

    1992-11-01

    The anaerobic biodegradability and toxicity of olive mill wastewaters (OMW) were studied in batch anaerobic digestion experiments. Anaerobic digestion of OMW or the supernatant of its centrifugation, the methane production was achieved at up to 5-15% (V/V) dilution corresponding to only 5-20 g/L COD. The washed suspended solids of OMW were toxic at up to 80 g/L COD; however, the kinetic of biodegradability of OMW or the supernatant was faster than for suspended solids, which are constituted mealy of cellulose and lignin. The darkly colored polyphenols induce the problem of biodegradation of OMW, whereas the long chain fatty acids (LCFA), tannins and simple phenolic compounds are responsible for its toxicity for methanogenic bacteria. 26 refs., 4 figs., 1 tab.

  16. Self-compassion training modulates alpha-amylase, heart rate variability, and subjective responses to social evaluative threat in women.

    Science.gov (United States)

    Arch, Joanna J; Brown, Kirk Warren; Dean, Derek J; Landy, Lauren N; Brown, Kimberley D; Laudenslager, Mark L

    2014-04-01

    A growing body of research has revealed that social evaluative stressors trigger biological and psychological responses that in chronic forms have been linked to aging and disease. Recent research suggests that self-compassion may protect the self from typical defensive responses to evaluation. We investigated whether brief training in self-compassion moderated biopsychological responses to the Trier Social Stress Test (TSST) in women. Compared to attention (placebo) and no-training control conditions, brief self-compassion training diminished sympathetic (salivary alpha-amylase), cardiac parasympathetic, and subjective anxiety responses, though not HPA-axis (salivary cortisol) responses to the TSST. Self-compassion training also led to greater self-compassion under threat relative to the control groups. In that social stress pervades modern life, self-compassion represents a promising approach to diminishing its potentially negative psychological and biological effects.

  17. Self-compassion training modulates alpha-amylase, heart rate variability, and subjective responses to social evaluative threat in women

    Science.gov (United States)

    Arch, Joanna J.; Brown, Kirk Warren; Dean, Derek J.; Landy, Lauren N.; Brown, Kimberley; Laudenslager, Mark L.

    2014-01-01

    A growing body of research has revealed that social evaluative stressors trigger biological and psychological responses that in chronic forms have been linked to aging and disease. Recent research suggests that self-compassion may protect the self from typical defensive responses to evaluation. We investigated whether brief training in self-compassion moderated biopsychological responses to the Trier Social Stress Test (TSST) in women. Compared to attention (placebo) and no-training control conditions, brief self-compassion training diminished sympathetic (salivary alpha-amylase), cardiac parasympathetic, and subjective anxiety responses, though not HPA-axis (salivary cortisol) responses to the TSST. Self-compassion training also led to greater self-compassion under threat relative to the control groups. In that social stress pervades modern life, self-compassion represents a promising approach to diminishing its potentially negative psychological and biological effects. PMID:24636501

  18. Skin barrier function in healthy volunteers as assessed by transepidermal water loss and vascular response to hexyl nicotinate: intra- and inter-individual variability.

    Science.gov (United States)

    Oestmann, E; Lavrijsen, A P; Hermans, J; Ponec, M

    1993-02-01

    This study assesses the variability of two non-invasive methods of measuring stratum corneum barrier function in vivo. Transepidermal water loss (TEWL), and the vascular response to hexyl nicotinate (HN) penetration as determined by laser-Doppler flowmetry, were measured in a group of 21 healthy volunteers. Each time profile of the vascular response to HN penetration was analysed using the following parameters: the baseline cutaneous blood flow, the lag-time between application and initial response (t0), the time between application and maximum response (tmax), the maximum response, and the slope of the curve. TEWL measured on the left volar forearm showed a normal range of 3.9-7.6 g/m2h and a small inter-individual variability [coefficient of variation (CV) 19.4%]. TEWL values at three other forearm sites did not show differences of clinical importance compared with the left volar forearm. The parameters of the vascular response to HN penetration spanned a wider normal range than the TEWL values (CV between 33 and 52%). Repeat measurements after a 1-2 month interval showed highly reproducible individual TEWL values. The mean difference between first and second measurements was only 0.03 g/m2h; the relative difference 0.6%. The intra-individual reproducibility of t0 and tmax. for HN penetration was also high (relative differences of 2.8 and 3.1%, respectively). The other vascular response parameters were less reproducible (relative differences of 6.9-18.6%). We conclude that TEWL and selected parameters of HN penetration, as non-invasive tests of the stratum corneum barrier function, yield reproducible results and are hence useful for investigations assessing the skin barrier function in various disorders.

  19. Heart rate variability in conscious neonatal swine: spectral features and responses to short-term intermittent hypoxia

    Directory of Open Access Journals (Sweden)

    Zhao Ning

    2006-06-01

    Full Text Available Abstract Background Spectral analysis of the cardiac time series has been used as a tool for assessing levels of parasympathetic and sympathetic modulation of the sinoatrial node. In the present investigation we evaluated daily changes in heart rate variability spectra in conscious neonatal piglets that were either neurally intact (n = 5 or had undergone right stellate ganglionectomy (n = 5. The partial stellectomized animals and their intact litter mates were exposed to four days of intermittent hypoxia, each day comprising nine episodes of hypoxia alternating with nine episodes of normoxia. A time control group (n = 7 comprised animals from different litters that were not exposed to intermittent hypoxia. We hypothesized that exposure to intermittent hypoxia would increase sympathetic efferent neuronal modulation of heart rate variability spectra in neurally intact animals and in those with right stellate ganglionectomy, and that his effect would be observed in heart rate variability spectra computed from baseline recordings. Results Overall, heart rate variability spectra during baseline conditions were dominated by high frequency activity, a reflection of parasympathetic efferent neuronal innervation and linkage to the ventilatory cycle manifested as respiratory sinus arrhythmia. Exposure to intermittent hypoxia did not alter daily baseline spectral features that would indicate an increase of sympathetic cardiac activity: low frequency (0.05 – 0.15 Hz activity was unaffected and the ratio of low- to -high frequency activity remained less than unity indicating a predominance of high frequency activity. The resultant spectra were remarkably similar despite differences in cardiac sympathetic efferent neuronal innervation and experimental treatment. When spectra were computed from cardiac time series during representative hypoxic episodes, significant increases in activity across the low frequency region (0.05 – 0.15 Hz of heart rate

  20. Biodegradable compounds: Rheological, mechanical and thermal properties

    Science.gov (United States)

    Nobile, Maria Rossella; Lucia, G.; Santella, M.; Malinconico, M.; Cerruti, P.; Pantani, R.

    2015-12-01

    Recently great attention from industry has been focused on biodegradable polyesters derived from renewable resources. In particular, PLA has attracted great interest due to its high strength and high modulus and a good biocompatibility, however its brittleness and low heat distortion temperature (HDT) restrict its wide application. On the other hand, Poly(butylene succinate) (PBS) is a biodegradable polymer with a low tensile modulus but characterized by a high flexibility, excellent impact strength, good thermal and chemical resistance. In this work the two aliphatic biodegradable polyesters PBS and PLA were selected with the aim to obtain a biodegradable material for the industry of plastic cups and plates. PBS was also blended with a thermoplastic starch. Talc was also added to the compounds because of its low cost and its effectiveness in increasing the modulus and the HDT of polymers. The compounds were obtained by melt compounding in a single screw extruder and the rheological, mechanical and thermal properties were investigated. The properties of the two compounds were compared and it was found that the values of the tensile modulus and elongation at break measured for the PBS/PLA/Talc compound make it interesting for the production of disposable plates and cups. In terms of thermal resistance the compounds have HDTs high enough to contain hot food or beverages. The PLA/PBS/Talc compound can be, then, considered as biodegradable substitute for polystyrene for the production of disposable plates and cups for hot food and beverages.

  1. Development of mold for biodegradable materials

    Energy Technology Data Exchange (ETDEWEB)

    Japitana, F.H.; Jabrica, A.M. [Metals Industry Research and Develeopment Center, Manila (Philippines). Dept. of Science and Technology; Komatsu, M. [Komatsu Consulting Engineer Office, Iwaki City, Fukushima (Japan); Takeuchi, Y. [Osaka Univ., Osaka (Japan). Dept. of Mechanical Engineering

    2008-07-01

    The improper disposal of non-biodegradable plastics adversely affect global environmental factors, principles of sustainability, industrial ecology and ecoefficiency. Therefore, a new generation of bio-based polymeric products has been developed. These polylactides (PLA), cellulose esters, starch plastics and polyhydroxyalkanoates (PHAs) are made from renewable natural resources and are biodegradable. They meet environmental conditions and can compete with their petrochemical counterparts. Among them, PLA is particularly attractive as a sustainable alternative to synthetic polymers and a potential candidate for the fabrication of biocomposites. Certain blends have proved successful in medical implants, sutures and drug delivery systems because of their capacity to dissolve away with time. However, widespread use of PLA is limited because of cost. Biodegradable plastic products are currently 6 to 10 times more expensive than traditional plastics. Environmentalists argue that the cheaper price of traditional plastics does not reflect their true cost when their impact is considered. This paper presented a solution to reduce the production cost of biodegradable plastics. In particular, it described a newly developed plastic injection mold for biodegradable materials which can produce a scrapless product. The system reduces processing time because it is not necessary to remove any gating or runners after the injection process. Takeout robots ensure that the quality of the product is maintained. 12 figs.

  2. Bio-Degradable Plastics Impact On Environment

    Directory of Open Access Journals (Sweden)

    T.SUBRAMANI

    2014-06-01

    Full Text Available The potential of biodegradable polymers and more particularly that of polymers obtained from renewable resources such as the polysaccharides (e.g., starch have long been recognized. However, these biodegradable polymers have been largely used in some applications (e.g., food industry and have not found extensive applications in the packaging industries to replace conventional plastic materials, although they could be an interesting way to overcome the limitation of the petrochemical resources in the future. The fossil fuel and gas could be partially replaced by greener agricultural sources, which should participate in the reduction of CO2 emissions. Bio-based and biodegradable plastics can form the basis for environmentally preferable, sustainable alternative to current materials based exclusively on petroleum feed stocks. These bio-based materials offer value in the sustainability/life-cycle equation by being a part of the biological carbon cycle, especially as it relates to carbon-based polymeric materials such as plastics, water soluble polymers and other carbon based products like lubricants, biodiesel, and detergents. Identification and quantification of bio based content uses radioactive C-14 signature. Biopolymers are generally capable of being utilized by living matter (biodegraded, and so can be disposed in safe and ecologically sound ways through disposal processes (waste management like composting, soil application, and biological wastewater treatment. Single use, short-life, disposable products can be engineered to be bio-based and biodegradable.

  3. Characterization of the Highly Variable Immune Response Gene Family, He185/333, in the Sea Urchin, Heliocidaris erythrogramma

    OpenAIRE

    Roth, Mattias O.; Wilkins, Adam G.; Cooke, Georgina M.; Raftos, David A; Nair, Sham V.

    2014-01-01

    This study characterizes the highly variable He185/333 genes, transcripts and proteins in coelomocytes of the sea urchin, Heliocidaris erythrogramma. Originally discovered in the purple sea urchin, Strongylocentrotus purpuratus, the products of this gene family participate in the anti-pathogen defenses of the host animals. Full-length He185/333 genes and transcripts are identified. Complete open reading frames of He185/333 homologues are analyzed as to their element structure, single nucleoti...

  4. Variability of Hormonal Stress Markers and Stress Responses in a Large Cross-Sectional Sample of Elephant Seals

    Science.gov (United States)

    2015-09-30

    increase our understanding of when stress has biologically significant effects on animals and identify potential mediators and mechanisms of those effects...the metabolic influence of cortisol on target tissues is mediated by carrier protein expression, primarily that of CBG. The exact role of CBG in...buffer mediating alterations in circulating corticosteroids. Nevertheless, assessing the level of circulating CBG and its variability over time permits

  5. Irregular response of nanofluid flow subject to chemical reaction and shape parameter in the presence of variable stream conditions

    Directory of Open Access Journals (Sweden)

    R. Kandasamy

    2016-09-01

    Full Text Available The problem of boundary layer of nanofluid flow which results from the stretching of a flat surface has been investigated numerically. The model includes the effects of Brownian motion, magnetic effect, non-linear velocity, variable thickness, thermophoresis, chemical reaction, porous medium, shape, thickness and heat source. The Partial differential equations are converted to ordinary deferential equations to solve analytically using shooting technique. The velocity, temperature and concentration profiles are discussed in detail for all parameters.

  6. Abnormal nocturnal heart rate variability response among chronic kidney disease and dialysis patients during wakefulness and sleep

    OpenAIRE

    Roumelioti, Maria-Eleni; Ranpuria, Reena; Hall, Martica; Hotchkiss, John R.; Chan, Chris T.; Mark L Unruh; Argyropoulos, Christos

    2010-01-01

    Background. Dialysis patients and patients with chronic kidney disease (CKD) experience a substantial risk for abnormal autonomic function and abnormal heart rate variability (HRV). It remains unknown whether HRV changes across sleep stages in patients with different severity of CKD or dialysis dependency. We hypothesized that high-frequency (HF) HRV (vagal tone) will be attenuated from wakefulness to non-rapid eye movement (NREM) and then to rapid eye movement (REM) sleep in dialysis patient...

  7. Methodological considerations regarding response bias effect in substance use research: is correlation between the measured variables sufficient?

    Directory of Open Access Journals (Sweden)

    Petróczi Andrea

    2011-01-01

    Full Text Available Abstract Efforts for drug free sport include developing a better understanding of the behavioural determinants that underline doping with an increased interest in developing anti-doping prevention and intervention programmes. Empirical testing of both is dominated by self-report questionnaires, which is the most widely used method in psychological assessments and sociology polls. Disturbingly, the potential distorting effect of socially desirable responding (SD is seldom considered in doping research, or dismissed based on weak correlation between some SD measure and the variables of interest. The aim of this report is to draw attention to i the potential distorting effect of SD and ii the limitation of using correlation analysis between a SD measure and the individual measures. Models of doping opinion as a potentially contentious issue was tested using structural equation modeling technique (SEM with and without the SD variable, on a dataset of 278 athletes, assessing the SD effect both at the i indicator and ii construct levels, as well as iii testing SD as an independent variable affecting expressed doping opinion. Participants were categorised by their SD score into high- and low SD groups. Based on low correlation coefficients (

  8. Econometric Analysis of Food Crops’ Response to Climate Variability and Macroeconomic Policies’ Reforms in Nigeria (1978-2009

    Directory of Open Access Journals (Sweden)

    Onoja, Anthony O.

    2012-09-01

    Full Text Available This study investigated the extent to which climate variability (proxied by rainfall variability and macroeconomic policies influenced food crop output in Nigeria. It used time series data obtained from Central Bank of Nigeria and National Bureau of Statistics (1978-2009. Four functional forms of OLS models were tried. The Cobb-Douglas function was finally adopted based on standard econometric model selection criteria and diagnosis. Chow test was used to test the hypotheses of the study. It was found that rainfall variability influenced crop output negatively. Climatic factor, loans guaranteed by Agricultural Credit Guarantee Scheme Fund and lending rate were all statistically significant drivers of crop output in the economy at p<0.05, p<0.01 and p<0.05 respectively. Their elasticities were respectively 4.01%, 0.52% and 0.98%. No structural difference between the economic reform era and the preceding era‟s regression coefficients was found. Programmes to stem corruption and loan diversion; subsidization of agricultural credit and climate change adaptation capacity building programmes were recommended to bring about sustainable food security in the country.

  9. Biodegradability of a polyacrylate superabsorbent in agricultural soil.

    Science.gov (United States)

    Wilske, Burkhard; Bai, Mo; Lindenstruth, Beate; Bach, Martin; Rezaie, Zahra; Frede, Hans-Georg; Breuer, Lutz

    2014-01-01

    Superabsorbent polymers (SAP) are used, inter alia, as soil amendment to increase the water holding capacity of soils. Biodegradability of soil conditioners has become a desired key characteristic to protect soil and groundwater resources. The present study characterized the biodegradability of one acrylate based SAP in four agricultural soils and at three temperatures. Mineralisation was measured as the (13)CO₂ efflux from (13)C-labelled SAP in soil incubations. The SAP was either single-labelled in the carboxyl C-atom or triple-labelled including additionally the two C-atoms interlinked in the SAP backbone. The dual labelling allowed estimating the degradation of the polyacrylate main chain. The (13)CO₂ efflux from samples was measured using an automated system including wavelength-scanned cavity ring-down spectroscopy. Based on single-labelled SAP, the mean degradation after 24 weeks varied between 0.45% in loamy sand and 0.82% in loam. However, the differences between degradation rates in different soils were not significant due to a large intra-replicate variability. Similarly, mean degradation did not differ significantly between effective temperature regimes of 20° and 30 °C after 12 weeks. Results from the triple-labelled SAP were lower as compared to their single-labelled variant. Detailed results suggest that the polyacrylate main chain degraded in the soils, if at all, at rates of 0.12-0.24 % per 6 months.

  10. The effects of biodegradation on the compositions of aromatic hydrocarbons and maturity indicators in biodegraded oils from Liaohe Basin

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    By the aid of GC-MS technique,a series of sequentially biodegraded oils from Liaohe Basin have been analyzed. The results show that the concentrations and relative compositions of various aromatic compounds in the biodegraded crude oils will change with increasing biodegradation degree. The concentrations of alkyl naphthalenes,alkyl phenanthrenes,alkyl dibenzothiophene are decreased,and the concentration of triaromatic steroids will increase with increasing biodegradation degree in biodegraded oils. Those phenomena indicate that various aromatic compounds are more easily biodegraded by bacteria like other kinds of hydrocarbons such as alkanes,but different series of aromatic compounds have a varied ability to resistant to biodegradation. The ratios of dibenzothiophene to phenenthrene(DBTH/P) and methyl dibenzothiophene to methyl phenanthrene(MDBTH/MP) are related to the features of depositional environment for source rocks such as redox and ancient salinity. However,in biodegraded oils,the two ratios increase quickly with the increase of the biodegradation degree,indicating that they have lost their geochemical significance. In this case,they could not be used to evaluate the features of depositional environment. Methyl phenanthrene index,methyl phenanthrene ratio and methyl dibenzoyhiophene ratio are useful aromatic maturity indicators for the crude oils and the source rocks without vitrinite. But for biodegraded oils,those aromatic maturity indicators will be affected by biodegradation and decrease with the increase of the biodegradation degree. Therefore,those aromatic molecular maturity indicators could not be used for biodegraded oils.

  11. Role for acetotrophic methanogens in methanogenic biodegradation of vinyl chloride

    Science.gov (United States)

    Bradley, P.M.; Chapelle, F.H.

    1999-01-01

    Under methanogenic conditions, stream-bed sediment microorganisms rapidly degraded [1,2-14C]vinyl chloride to 14CH4 and 14CO2. Amendment with 2-bromoethanesulfonic acid eliminated 14CH4 production and decreased 14CO2 recovery by an equal molar amount. Results obtained with [14C]ethene, [14C]acetate, or 14CO2 as substrates indicated that acetotrophic methanogens were responsible for the production of 14CH4 during biodegradation of [1,2-14C]VC.Under methanogenic conditions, stream-bed sediment microorganisms rapidly degraded [1,2-14C]vinyl chloride to 14CH4 and 14CO2. Amendment with 2-bromoethanesulfonic acid eliminated 14CH4 production and decreased 14CO2 recovery by an equal molar amount. Results obtained with [14C]-ethene, [14C]acetate, or 14CO2 as substrates indicated that acetotrophic methanogens were responsible for the production of 14CH4, during biodegradation of [1,2-14C]VC.

  12. Biodegradability of degradable plastic waste.

    Science.gov (United States)

    Agamuthu, P; Faizura, Putri Nadzrul

    2005-04-01

    Plastic waste constitutes the third largest waste volume in Malaysian municipal solid waste (MSW), next to putrescible waste and paper. The plastic component in MSW from Kuala Lumpur averages 24% (by weight), whereas the national mean is about 15%. The 144 waste dumps in the country receive about 95% of the MSW, including plastic waste. The useful life of the landfills is fast diminishing as the plastic waste stays un-degraded for more than 50 years. In this study the compostability of polyethylene and pro-oxidant additive-based environmentally degradable plastics (EDP) was investigated. Linear low-density polyethylene (LLDPE) samples exposed hydrolytically or oxidatively at 60 degrees C showed that the abiotic degradation path was oxidative rather than hydrolytic. There was a weight loss of 8% and the plastic has been oxidized as shown by the additional carbonyl group exhibited in the Fourier transform infra red (FTIR) Spectrum. Oxidation rate seemed to be influenced by the amount of pro-oxidant additive, the chemical structure and morphology of the plastic samples, and the surface area. Composting studies during a 45-day experiment showed that the percentage elongation (reduction) was 20% for McD samples [high-density polyethylene, (HDPE) with 3% additive] and LL samples (LLDPE with 7% additive) and 18% reduction for totally degradable plastic (TDP) samples (HDPE with 3% additive). Lastly, microbial experiments using Pseudomonas aeroginosa on carbon-free media with degradable plastic samples as the sole carbon source, showed confirmatory results. A positive bacterial growth and a weight loss of 2.2% for degraded polyethylene samples were evident to show that the degradable plastic is biodegradable.

  13. Introduction of environmentally degradable parameters to evaluate the biodegradability of biodegradable polymers.

    Directory of Open Access Journals (Sweden)

    Wenbin Guo

    Full Text Available Environmentally Degradable Parameter ((EdK is of importance in the describing of biodegradability of environmentally biodegradable polymers (BDPs. In this study, a concept (EdK was introduced. A test procedure of using the ISO 14852 method and detecting the evolved carbon dioxide as an analytical parameter was developed, and the calculated (EdK was used as an indicator for the ultimate biodegradability of materials. Starch and polyethylene used as reference materials were defined as the (EdK values of 100 and 0, respectively. Natural soil samples were inoculated into bioreactors, followed by determining the rates of biodegradation of the reference materials and 15 commercial BDPs over a 2-week test period. Finally, a formula was deduced to calculate the value of (EdK for each material. The (EdK values of the tested materials have a positive correlation to their biodegradation rates in the simulated soil environment, and they indicated the relative biodegradation rate of each material among all the tested materials. Therefore, the (EdK was shown to be a reliable indicator for quantitatively evaluating the potential biodegradability of BDPs in the natural environment.

  14. Biodegradable nanoparticles for gene therapy technology

    Energy Technology Data Exchange (ETDEWEB)

    Hosseinkhani, Hossein, E-mail: hosseinkhani@mail.ntust.edu.tw; He, Wen-Jie [National Taiwan University of Science and Technology (Taiwan Tech), Graduate Institute of Biomedical Engineering (China); Chiang, Chiao-Hsi [School of Pharmacy, National Defense Medical Center (China); Hong, Po-Da [National Taiwan University of Science and Technology (Taiwan Tech), Graduate Institute of Biomedical Engineering (China); Yu, Dah-Shyong [Nanomedicine Research Center, National Defense Medical Center (China); Domb, Abraham J. [The Hebrew University of Jerusalem, Institute of Drug Research, School of Pharmacy, Faculty of Medicine, Center for Nanoscience and Nanotechnology and The Alex Grass Center for Drug Design and Synthesis (Israel); Ou, Keng-Liang [College of Oral Medicine, Taipei Medical University, Research Center for Biomedical Devices and Prototyping Production (China)

    2013-07-15

    Rapid propagations in materials technology together with biology have initiated great hopes in the possibility of treating many diseases by gene therapy technology. Viral and non-viral gene carriers are currently applied for gene delivery. Non-viral technology is safe and effective for the delivery of genetic materials to cells and tissues. Non-viral systems are based on plasmid expression containing a gene encoding a therapeutic protein and synthetic biodegradable nanoparticles as a safe carrier of gene. Biodegradable nanoparticles have shown great interest in drug and gene delivery systems as they are easy to be synthesized and have no side effect in cells and tissues. This review provides a critical view of applications of biodegradable nanoparticles on gene therapy technology to enhance the localization of in vitro and in vivo and improve the function of administered genes.

  15. Biodegradable Materials for Bone Repairs: A Review

    Institute of Scientific and Technical Information of China (English)

    Lili Tan; Xiaoming Yu; Peng Wan; Ke Yang

    2013-01-01

    With attractive research and development of biomaterials,more and more opportunities have been brought to the treatments of human tissue repairs.The implant is usually no need to exist in the body accompanied with the recovery or regeneration of the tissue lesions,and the long-term effect of exotic substance to human body should be reduced as lower as possible.For this purpose,biodegradable materials,including polymers,magnesium alloys and ceramics,have attracted much attention for medical applications due to their biodegradable characters in body environment.This paper in turn introduces these three different types of widely studied biodegradable materials as well as their advantages as implants in applications for bone repairs.Relevant history and research progresses are summarized.

  16. Novel biodegradable nanocarriers for enhanced drug delivery.

    Science.gov (United States)

    Gagliardi, Mariacristina

    2016-12-01

    With the refinement of functional properties, the interest around biodegradable materials, in biorelated applications and, in particular, in their use as controlled drug-delivery systems, increased in the last decades. Biodegradable materials are an ideal platform to obtain nanoparticles for spatiotemporal controlled drug delivery for the in vivo administration, thanks to their biocompatibility, functionalizability, the control exerted on delivery rates and the complete degradation. Their application in systems for cancer treatment, brain and cardiovascular diseases is already a consolidated practice in research, while the bench-to-bedside translation is still late. This review aims at summarizing reported applications of biodegradable materials to obtain drug-delivery nanoparticles in the last few years, giving a complete overview of pros and cons related to degradable nanomedicaments.

  17. Biodegradable Hybrid Stomatocyte Nanomotors for Drug Delivery.

    Science.gov (United States)

    Tu, Yingfeng; Peng, Fei; André, Alain A M; Men, Yongjun; Srinivas, Mangala; Wilson, Daniela A

    2017-02-28

    We report the self-assembly of a biodegradable platinum nanoparticle-loaded stomatocyte nanomotor containing both PEG-b-PCL and PEG-b-PS as a potential candidate for anticancer drug delivery. Well-defined stomatocyte structures could be formed even after incorporation of 50% PEG-b-PCL polymer. Demixing of the two polymers was expected at high percentage of semicrystalline poly(ε-caprolactone) (PCL), resulting in PCL domain formation onto the membrane due to different properties of two polymers. The biodegradable motor system was further shown to move directionally with speeds up to 39 μm/s by converting chemical fuel, hydrogen peroxide, into mechanical motion as well as rapidly delivering the drug to the targeted cancer cell. Uptake by cancer cells and fast doxorubicin drug release was demonstrated during the degradation of the motor system. Such biodegradable nanomotors provide a convenient and efficient platform for the delivery and controlled release of therapeutic drugs.

  18. Biodegradation of resorcinol by Pseudomonas sp.

    Directory of Open Access Journals (Sweden)

    Nader Hajizadeh

    2016-11-01

    Full Text Available Objective: To investigate the ability of Pseudomonas sp. isolated from East Azarbaijan, Iran in bioremediation of resorcinol. Methods: Resorcinol biodegradation was evaluated using spectrophotometry and confirmed by gas chromatography-mass spectroscopy. Results: This isolate was able to remove up to 37.12% of resorcinol from contaminated water. Reusability experiments had confirmed the biodegradation process which produced seven intermediate compounds. These intermediates were characterized by gas chromatographymass spectroscopy technique. The products of resorcinol biodegradation were apparently 1, 4-cyclohexadiene, nonadecene, 2-heptadecanone, 1-isopropyl-2-methoxy-4-methylbenzene, hexadecanoic acid, 9-octadecenoic acid, phenol and 5-methyl-2-(1-methylethyl. Conclusions: The findings revealed that Pseudomonas sp. is able to degrade resorcinol. Because of being an indigenous organism, this isolate is more compatible with the climate of the northwest region of Iran and possibly will be used for degradation of other similar aromatic compounds.

  19. Biodegradation of resorcinol byPseudomonas sp.

    Institute of Scientific and Technical Information of China (English)

    Nader Hajizadeh; Najibeh Shirzad; Ali Farzi; Mojtaba Salouti; Azra Momeni

    2016-01-01

    ABSTRACT Objective:To investigate the ability ofPseudomonas sp. isolated from East Azarbaijan, Iran in bioremediation of resorcinol. Methods: Resorcinol biodegradation was evaluated using spectrophotometry and confirmed by gas chromatography-mass spectroscopy. Results:This isolate was able to remove up to 37.12% of resorcinol from contaminated water. Reusability experiments had confirmed the biodegradation process which produced seven intermediate compounds. These intermediates were characterized by gas chromatography-mass spectroscopy technique. The products of resorcinol biodegradation were apparently 1, 4-cyclohexadiene, nonadecene, 2-heptadecanone, 1-isopropyl-2-methoxy-4-methylbenzene, hexadecanoic acid, 9-octadecenoic acid, phenol and 5-methyl-2-(1-methylethyl). Conclusions: The findings revealed thatPseudomonas sp. is able to degrade resorcinol. Because of being an indigenous organism, this isolate is more compatible with the climate of the northwest region of Iran and possibly will be used for degradation of other similar aromatic compounds.

  20. Biodegradable Polymers and Stem Cells for Bioprinting.

    Science.gov (United States)

    Lei, Meijuan; Wang, Xiaohong

    2016-04-29

    It is imperative to develop organ manufacturing technologies based on the high organ failure mortality and serious donor shortage problems. As an emerging and promising technology, bioprinting has attracted more and more attention with its super precision, easy reproduction, fast manipulation and advantages in many hot research areas, such as tissue engineering, organ manufacturing, and drug screening. Basically, bioprinting technology consists of inkjet bioprinting, laser-based bioprinting and extrusion-based bioprinting techniques.