bluuebunny/crossref_metadata_2025 huggingface dataset:
Enhancing the utility of complex‐valued functional magnetic resonance imaging detection of neurobiological processes through postacquisition estimation and correction of dynamic B0 errors and motion
Authors: Hahn Andrew D. , Nencka Andrew S. , Rowe Daniel B.
Published: February 2011

Functional magnetic resonance imaging (fMRI) time series analysis is typically performed using only the magnitude portion of the data. The phase information remains unused largely due to its sensitivity to temporal variations in the magnetic field unrelated to the functional response of interest. These phase changes are commonly the result of physiologic processes such as breathing or motion either inside or outside the imaging field of view. As a result, although the functional phase response carries pertinent physiological information concerning the vasculature, one aspect of which is the location of large draining veins, the full hemodynamic phase response is understudied and is poorly understood, especially in comparison with the magnitude response. It is likely that the magnitude and phase contain disjoint information, which could be used in tandem to better characterize functional hemodynamics. In this work, simulated and human fMRI experimental data are used to demonstrate how statistical analysis of complex‐valued fMRI time series can be problematic, and how robust analysis using these powerful and flexible complex‐valued statistics is possible through postprocessing with correction for dynamic magnetic field fluctuations in conjunction with estimated motion parameters. These techniques require no special pulse sequence modifications and can be applied to any complex‐valued echo planar imaging data set. This analysis shows that the phase component appears to contain information complementary to that in the magnitude and that processing and analysis techniques are available to investigate it in a robust and flexible manner. Hum Brain Mapp, 2012. © 2011 Wiley Periodicals, Inc.
The impact of long‐term participation in the supplemental nutrition assistance program on child obesity
Authors: Schmeiser Maximilian D.
Published: February 2011

Participation in the Supplemental Nutrition Assistance Program (SNAP) reached an all‐time high of 40.2 million persons in March 2010, which means the program affects a substantial fraction of Americans. A significant body of research has emerged suggesting that participation in SNAP increases the probability of being obese for adult women and has little effect on the probability for adult men. However, studies addressing the effects of participation on children have produced mixed results. This paper examines the effect of long‐term SNAP participation on the Body Mass Index (BMI) percentile and probability of being overweight or obese for children ages 5–18 using data from the National Longitudinal Survey of Youth 1979 Children and Young Adults data set. An instrumental variables identification strategy that exploits exogenous variation in state‐level program parameters, as well as state and federal expansions of the Earned Income Tax Credit (EITC), is used to address the endogeneity between SNAP participation and obesity. SNAP participation is found to significantly reduce BMI percentile and the probability of being overweight or obese for boys and girls ages 5–11 and boys ages 12–18. For girls ages 12–18, SNAP participation appears to have no significant effect on these outcomes. Copyright © 2011 John Wiley & Sons, Ltd.
Scheduling jobs to consider physiological factors
Authors: Öztürkoğlu Yücel Yılmaz , Bulfin Robert L.
Published: February 2011

We studied scheduling jobs and breaks for a single worker. The processing time of jobs increases as the worker tires. In this study, we assume that conventional machine scheduling models do not always work for humans. So, while determining the break time, we consider the workers' physiological factors. The two objectives considered are the total flow time and makespan. An exact mathematical model and heuristic algorithm are developed to solve large problems. Numerical examples are presented for understanding and analyzing the performance of the mathematical model and the heuristic. © 2011 Wiley Periodicals, Inc.
Prolactin as a biomarker for treatment response and tardive dyskinesia in schizophrenia subjects: old thoughts revisited from a genetic perspective
Authors: Souza Renan P. , Meltzer Herbert Y. , Lieberman Jeffrey A. , Voineskos Aristotle N. , Remington Gary , Kennedy James L.
Published: February 2011

Previous studies investigated whether prolactin (PRL) serum level was a biomarker of antipsychotic response, schizophrenia symptomatology, and tardive dyskinesia. Most of the findings support that antipsychotic drugs modulate PRL levels but PRL is not a steady indicator. Recent results suggest a genetic effect of PRL and PRL receptor (PRLR) polymorphisms in PRL levels indicating that independently of antipsychotic therapy subjects could have altered PRL levels due to their genetic background. We evaluated whether PRL and PRLR variants were associated with treatment outcome and tardive dyskinesia. We observed no association of PRL/PRLR polymorphism with treatment response (best genotypic results include PRL rs849885 and PRLR rs4703509 permuted p = 0.326). Regarding tardive dyskinesia, the major allele of PRL rs37364 was nominally associated with risk for tardive dyskinesia in the European ancestry sub‐sample (permuted p = 0.183). Although we reported no significant associations, it is definitely worthy of investigation to see if together (genetic variants in the PRL system and PRL serum measures) could be a reliable biomarker for antipsychotic response and TD prevalence. Our results suggest that more studies in this context are required to shed light in the molecular mechanisms underlying antipsychotic response and tardive dyskinesia occurrence. Copyright © 2011 John Wiley & Sons, Ltd.
The comparison of aripiprazole and risperidone augmentation in selective serotonin reuptake inhibitor‐refractory obsessive‐compulsive disorder: a single‐blind, randomised study
Authors: Selvi Yavuz , Atli Abdullah , Aydin Adem , Besiroglu Lutfullah , Ozdemir Pinar , Ozdemir Osman
Published: February 2011

Objective

To investigate the comparative efficacy of aripiprazole and risperidone as augmenting agents in the treatment of obsessive‐compulsive disorder (OCD) patients who did not show a ≥35% decrease in the Yale‐Brown Obsessive‐Compulsive Scale (Y‐BOCS) after 12‐week monotherapy with selective serotonin reuptake inhibitors (SSRIs).

Methods

The study consists of two different periods of treatment: a 12‐week prospective period to determine resistance to SSRI treatment and an 8‐week single‐blind addition period for refractory patients only. Ninety patients were randomly assigned to receive one of the SSRI treatments. Sixty‐nine patients (76.6%) completed the 12‐week SSRI monotherapy period. Forty‐one patients (59.4%) were considered refractory and were randomised to receive either risperidone (20 patients, 3 mgr daily) or aripiprazole (21 patients, 15 mgr daily) as augmentation to SSRI treatment. Sixteen patients (76.2%) in the aripiprazole group and 18 patients (84%) in the risperidone group completed the 8‐week treatment period.

Results

Eight patients (50%) in aripiprazole and 13 patients (72.2%) in risperidone group met response criteria of Y‐BOCS decrease ≥35% at the end of the study. The risperidone group showed a significant improvement in Y‐BOCS obsession scores compared with aripiprazole.

Conclusions

The present findings suggest that risperidone may be more effective than aripiprazole. Copyright © 2011 John Wiley & Sons, Ltd.
The acute effect of Swedish‐style snus on cigarette craving and self‐administration in male and female smokers
Authors: Barrett Sean P. , Campbell Mallory L. , Temporale Kirsten , Good Kim Berley P.
Published: February 2011

Introduction

Swedish‐style snus (SS) has recently garnered controversy for its proposed use as a smoking cessation aid and/or harm reduction tool. However, to date, little work has been done to evaluate the extent to which SS affects cigarette cravings and smoking behavior under double‐blind controlled conditions.

Methods

During four double‐blind placebo‐controlled randomized sessions, 15 smokers (8 male) administered SS, placebo (nicotine/tobacco‐free) snus (PS), a nicotine‐containing lozenge (NL), or a placebo lozenge (PL) for 30 min and assessed their effects using Visual Analogue Scales and the Brief Questionnaire of Smoking Urges. They could then self‐administer their usual brand of cigarettes using a progressive ratio task over the next 60 min. Following the completion of their final session, 11 participants (6 male) ranked each of the products used in the study in terms of their preferences.

Results

Relative to the other products, SS was associated with a decreased intention to smoke as well as a delayed onset of cigarette smoking in men but not women. However, SS administration was also associated with increased feelings of frustration and irritability relative to NL and SS was ranked as being the least preferred product used in the study.

Discussion

Findings suggest that SS is effective in acutely suppressing craving and smoking in at least some smokers, but that its acceptability may be limited. Copyright © 2011 John Wiley & Sons, Ltd.
Novel combination strategy to optimize treatment for PTSD
Authors: Shad Mujeeb U. , Suris Alina M. , North Carol S.
Published: February 2011

Post‐traumatic stress disorder (PTSD) is increasingly recognized as a serious and potentially debilitating condition in combat veterans returning from Iraq and Afghanistan. Exposure to a potentially life‐threatening event such as military combat may be followed by PTSD. Despite recent advances in pharmacotherapy for PTSD, monotherapy with the currently available medications is only partially effective, as demonstrated in large clinical trials of combat veterans with PTSD. This underscores the need to investigate novel combination strategies to enhance treatment response in PTSD. The α‐1 adrenergic receptor (AR) antagonist, prazosin, appears promising in recent studies for its capacity to reduce trauma‐related nightmares (a group B night‐time intrusion symptom) and insomnia (a group D night‐time arousal symptom), while recent evidence supports using the β‐AR antagonist, propranolol, to dampen the emotional content of traumatic memories (daytime intrusion symptoms including flashbacks, intrusive recollections of traumatic event, and heightened physiological reactivity/responsivity to trauma reminders). In this review, we present data supporting the potential utility of combined drug regimen (prazosin and propranolol) acting through different noradrenergic mechanisms, with the potential to target more than one set of PTSD symptoms to optimize PTSD treatment. Copyright © 2011 John Wiley & Sons, Ltd.
Sensitivity of mean transit time estimates to model conditioning and data availability
Authors: Hrachowitz M. , Soulsby C. , Tetzlaff D. , Malcolm I. A.
Published: February 2011

Mean transit times (MTTs) can give useful insights into the internal processes of hydrological systems. However, varying model conditioning assumptions and data availability can limit the use of MTT, particularly in terms of comparing the results of studies using different assumptions and data records of varying lengths. We present a systematic analysis of sensitivity of MTT estimates to different methods of artificially extending the data record, varying model warm‐up period lengths and varying sampling intervals for a small upland catchment in the Scottish Highlands. The analysis was based on Cl−data in conjunction with the convolution integral model using the gamma distribution as transit time distribution. It could be shown that three out of four different methods to artificially extend the data record and to generate a warm‐up period give mostly equivalent results. The required minimum warm‐up period length to reliably estimate MTT for a 3‐year period of data was observed to be about 2 years or 3 times the MTT, implying that ∼95% of the tracer signal entering the stream at day 1 of the warm‐up period has to be recovered by the end of the warm‐up period in order to avoid significant deviations from the best available MTT estimates. It was furthermore found that sampling intervals of up to 4 weeks can produce MTT estimates within about 0·25 times the best available MTT estimate, albeit with potentially increased process misrepresentation in terms of the gamma distribution parameter α. Copyright © 2011 John Wiley & Sons, Ltd.
Seasonal rainfall–runoff relationships in a lowland forested watershed in the southeastern USA
Authors: La Torre Torres Ileana B. , Amatya Devendra M. , Sun Ge , Callahan Timothy J.
Published: February 2011

Hydrological processes of lowland watersheds of the southern USA are not well understood compared to a hilly landscape due to their unique topography, soil compositions, and climate. This study describes the seasonal relationships between rainfall patterns and runoff (sum of storm flow and base flow) using 13 years (1964–1976) of rainfall and stream flow data for a low‐gradient, third‐order forested watershed. It was hypothesized that runoff–rainfall ratios (R/P) are smaller during the dry periods (summer and fall) and greater during the wet periods (winter and spring). We found a large seasonal variability in event R/P potentially due to differences in forest evapotranspiration that affected seasonal soil moisture conditions. Linear regression analysis results revealed a significant relationship between rainfall and runoff for wet (r2 = 0·68; p < 0·01) and dry (r2 = 0·19; p = 0·02) periods. Rainfall‐runoff relationships based on a 5‐day antecedent precipitation index (API) showed significant (r2 = 0·39; p < 0·01) correspondence for wet but not (r2 = 0·02; p = 0·56) for dry conditions. The same was true for rainfall‐runoff relationships based on 30‐day API (r2 = 0·39; p < 0·01 for wet and r2 = 0·00; p = 0·79 for dry). Stepwise regression analyses suggested that runoff was controlled mainly by rainfall amount and initial soil moisture conditions as represented by the initial flow rate of a storm event. Mean event R/P were higher for the wet period (R/P = 0·33), and the wet antecedent soil moisture condition based on 5‐day (R/P = 0·25) and 30‐day (R/P = 0·26) prior API than those for the dry period conditions. This study suggests that soil water status, i.e. antecedent soil moisture and groundwater table level, is important besides the rainfall to seasonal runoff generation in the coastal plain region with shallow soil argillic horizons. Copyright © 2011 John Wiley & Sons, Ltd.
Response analysis of rainfall–runoff processes using wavelet transform: a case study of the alpine meadow belt
Authors: Liu Hai‐Long , Bao An‐Ming , Chen Xi , Wang Ling , Pan Xiang‐liang
Published: February 2011

Rainfall–runoff processes appear to be highly nonlinear in Bayinbluk watersheds of the northwestern China. In this study, the time‐scale wavelet transform has been used for the analysis of this nonstationary system. The Haar and Morlet wavelet transform were used to analyse the rainfall–runoff conversion relationship. Wavelet power spectrum and change point methods are also employed to analyse rainfall rates and runoffs measured at daily to half‐hourly sampling rate. The four experimental sites (Luoto, Haer, Kuce and Shengl) are located in the Tianshan Mountains (Xinjiang province, China). Correlation analysis and wavelet transform are first applied to runoff process in different underlying surfaces. Wavelet analyses of rainfall rates and runoffs also give meaningful information on the temporal variability of the rainfall–runoff relationship. Change point and wavelet power spectrum analysis provide simple interpretation of energy distribution between different scales. The results indicate that wavelet transform is a good method for analysing the nonlinear relationship of temporal–spatial responses between rainfall and runoff. This method allowed quantification of the processes affecting runoff and provided an insight into their implications in surface water management. Copyright © 2011 John Wiley & Sons, Ltd.
Causes of systematic over‐ or underestimation of low streamflows by use of index‐streamgage approaches in the United States
Authors: Eng Ken , Kiang Julie E. , Chen Yin‐Yu , Carlisle Daren M. , Granato Gregory E.
Published: February 2011

Low‐flow characteristics can be estimated by multiple linear regressions or the index‐streamgage approach. The latter transfers streamflow information from a hydrologically similar, continuously gaged basin (‘index streamgage’) to one with a very limited streamflow record, but often results in biased estimates. The application of the index‐streamgage approach can be generalized into three steps: (1) selection of streamflow information of interest, (2) definition of hydrologic similarity and selection of index streamgage, and (3) application of an information‐transfer approach. Here, we explore the effects of (1) the range of streamflow values, (2) the areal density of streamgages, and (3) index‐streamgage selection criteria on the bias of three information‐transfer approaches on estimates of the 7‐day, 10‐year minimum streamflow (Q7, 10). The three information‐transfer approaches considered are maintenance of variance extension, base‐flow correlation, and ratio of measured to concurrent gaged streamflow (Q‐ratio invariance). Our results for 1120 streamgages throughout the United States suggest that only a small portion of the total bias in estimated streamflow values is explained by the areal density of the streamgages and the hydrologic similarity between the two basins. However, restricting the range of streamflow values used in the index‐streamgage approach reduces the bias of estimated Q7, 10 values substantially. Importantly, estimated Q7, 10 values are heavily biased when the observed Q7, 10 values are near zero. Results of the analysis also showed that Q7, 10 estimates from two of the three index‐streamgage approaches have lower root‐mean‐square error values than estimates derived from multiple regressions for the large regions considered in this study. Published in 2011 by John Wiley & Sons, Ltd.
Deriving the relationship among discharge, biomass and Manning's coefficient through a calibration approach
Authors: De Doncker L. , Troch P. , Verhoeven R. , Buis K.
Published: February 2011

The subject of environmental engineering is currently of great interest. Field experiments as well as numerical models have proven their worth in this research field. An introduction to hydrodynamic modelling, coupled to the modelling of vegetation biomass is described. The developed Strive (STream RIVer Ecosystem) model is set up in the Femme (‘Flexible Environment for Mathematically Modelling the Environment’) environment and has already proven its worth in a large number of calculations (De Doncker et al., 2006, 2008b). Discharges and water levels are modelled together with modelling of electrical conductivity (EC). Extensive measurement campaigns are carried out to collect a large number of observations and calibration of the model is based on this data set. Furthermore, calibration methods and the discussion of this process are displayed. As a result, it is seen that the developed Strive model can model both, hydrodynamic and ecological processes, in an accurate way. The work highlights the importance of detailed determination of Manning's coefficient, dependent on discharge and amount of biomass, as an important calibration parameter for accurate modelling. Copyright © 2011 John Wiley & Sons, Ltd.
Contribution of glacier meltwater to streamflow in the Wind River Range, Wyoming, inferred via a Bayesian mixing model applied to isotopic measurements
Authors: Cable Jessica , Ogle Kiona , Williams David
Published: February 2011

The Wind River Range (WRR) of Wyoming has the largest concentration of alpine glaciers in the American Rockies and contributes to several major river systems in the western United States. Declines in the areal extent and volume of these glaciers are well documented, and eventual loss of alpine glaciers will reduce the amount of water available for agricultural and domestic use. The contribution of glacial melt to streamflow remains largely unquantified in Wyoming. We used isotope measurements and Bayesian modeling to estimate the fractional contribution of glacier meltwater to Dinwoody Creek (DC) in the WRR on bi‐weekly and seasonal (spring, summer, and fall) time scales over 2 years. In 2007 and 2008, we made temporally intensive measurements of the stable isotope composition of water from the DC watershed. Samples of the primary sources of streamflow (snowmelt, glacier melt, rain, and baseflow) were collected during field campaigns, and automated collection of stream samples occurred over the melt season. Isotope data (D and18O) were analyzed within a hierarchical Bayesian framework that incorporated temporal and spatial correlations. Glacial melt contributed a significant proportion (∼53–59%) to streamflow in a low‐flow year (2007) or when streamflow was low during a high‐flow year (2008). In 2008, a large and persistent snowpack contributed significantly (∼0·42–51%) to streamflow in mid‐summer. The large contribution of glacial melt to streamflow suggests that the loss of glaciers may impact riparian ecosystems and human water supplies in the late summer and in years with low snowpack. Copyright © 2011 John Wiley & Sons, Ltd.
Entropy, consistency in rainfall distribution and potential water resource availability in Australia
Authors: Hasan Md Masud , Dunn Peter K
Published: February 2011

Understanding the variability in monthly rainfall amounts is important for the management of water resources. We use entropy, a measure of variability, to quantify the rainfall variability in Australia. We define the entropy of stable rainfall (ESR) to measure the long‐term average rainfall variability across the months of the year. The stations in northern Australia observe substantially more variability in rainfall distributions and stations in southern Australia observe less variability in rainfall distribution across the months of the year. We also define the consistency index (CI) to compare the distribution of the monthly rainfall for a given year with the long‐term average monthly rainfall distribution. Higher value of the CI indicates the rainfall in the year is consistent with the overall long‐term average rainfall distribution. Areas close to the coastline in northern, southern and eastern Australia observe more consistent rainfall distribution in individual years with the long‐term average rainfall distribution. For the studied stations, we categorize the years into different potential water resource availability on the basis of annual rainfall amount and CI. For almost all Australian rainfall stations, El Niño years have a greater risk of having below median and relatively inconsistent rainfall distribution than La Niña years. The results may be helpful for developing area‐specific water usage strategies. Copyright © 2011 John Wiley & Sons, Ltd.
A soft hydrological monitoring approach for comparing runoff on a network of small poorly gauged catchments
Authors: Crabit Armand , Colin François , Moussa Roger
Published: February 2011

Catchments in many parts of the world are either ungauged or poorly gauged, and the dominant processes governing their streamflow response are still poorly understood. The analysis of runoff coefficients provides essential insight into catchment response, particularly if both range of catchments and a range of events are compared. This paper investigates how well the hydrological runoff of 11 small, poorly gauged catchments with ephemeral streams (0·1‐0·6 km2) can be compared using estimated runoff with the associated uncertainty. Data of rainfall and water depth at a catchment's outlet were recorded using automatic logging equipment during 2008‐2009. The hydrological regime is intermittent and the annual precipitation ranged between 569 and 727 mm. Discharge was estimated using Manning's equation and channel cross‐section measurements. Innovative work has been performed under controlled experimental conditions to estimate Manning's coefficient values for the different cover types observed in studied streams: non‐aquatic vegetations (giant reed, bramble and thistle), grass and coarse granular deposits. The results show that estimates derived using roughness coefficients differ from those previously established for larger streams with aquatic vegetation. Catchment runoff was compared at both the event and the annual scale. The results indicate significant variability between the catchment's responses. This variability allows for classification in spite of all the uncertainty associated with runoff estimation. This study highlights the potential of using a network of poorly gauged catch ments. From almost no catchment understanding the proposed methodology allows to compare poorly gauged catchments and highlights similarity/dissimilarity between catchment responses. Copyright © 2011 John Wiley & Sons, Ltd.
Assessing the uncertainties of hydrologic model selection in climate change impact studies
Authors: Najafi M. R. , Moradkhani H. , Jung I. W.
Published: February 2011

The uncertainties associated with atmosphere‐ocean General Circulation Models (GCMs) and hydrologic models are assessed by means of multi‐modelling and using the statistically downscaled outputs from eight GCM simulations and two emission scenarios. The statistically downscaled atmospheric forcing is used to drive four hydrologic models, three lumped and one distributed, of differing complexity: the Sacramento Soil Moisture Accounting (SAC‐SMA) model, Conceptual HYdrologic MODel (HYMOD), Thornthwaite‐Mather model (TM) and the Precipitation Runoff Modelling System (PRMS). The models are calibrated based on three objective functions to create more plausible models for the study. The hydrologic model simulations are then combined using the Bayesian Model Averaging (BMA) method according to the performance of each models in the observed period, and the total variance of the models. The study is conducted over the rainfall‐dominated Tualatin River Basin (TRB) in Oregon, USA. This study shows that the hydrologic model uncertainty is considerably smaller than GCM uncertainty, except during the dry season, suggesting that the hydrologic model selection‐combination is critical when assessing the hydrologic climate change impact. The implementation of the BMA in analysing the ensemble results is found to be useful in integrating the projected runoff estimations from different models, while enabling to assess the model structural uncertainty. Copyright © 2011 John Wiley & Sons, Ltd.
Comparison of bootstrap confidence intervals for an ANN model of a karstic aquifer response
Authors: Trichakis Ioannis , Nikolos Ioannis , Karatzas George P.
Published: February 2011

Following many applications artificial neural networks (ANNs) have found in hydrology, a question has been rising for quantification of the output uncertainty. A pre‐optimized ANN simulated the hydraulic head change at two observation wells, having as input hydrological and meteorological parameters. In order to calculate confidence intervals (CI) for the ANN output two bootstrap methods were examined namely bootstrap percentile and BCa (Bias‐Corrected and accelerated). The actual coverage of the CI was compared to the theoretical coverage for different certainty levels as a means of examining the method's reliability. The results of this work support the idea that the bootstrap methods provide a simple tool for confidence interval computation of ANNs. Comparing the two methods, the percentile requires fewer calculations and yields narrower intervals with similar actual coverage to that of BCa. Overall, the actual coverage was proved lower than desired when not modeled points were present in the data subset. Copyright © 2011 John Wiley & Sons, Ltd.
Comparing satellite derived precipitation datasets using the Hillslope River Routing (HRR) model in the Congo River Basin
Authors: Beighley R. E. , Ray R. L. , He Y. , Lee H. , Schaller L. , Andreadis K. M. , Durand M. , Alsdorf D. E. , Shum C. K.
Published: February 2011

In this paper, three satellite derived precipitation datasets (TRMM, CMORPH, PERSIANN) are used to drive the Hillslope River Routing (HRR) model in the Congo Basin. The precipitation data are compared spatially and temporally in two forms: (1) precipitation magnitudes, and (2) resulting streamflow and water storages. Simulated streamflow is assessed using historical monthly discharge data from in situ stream gauges and recent stage data based on water surface elevations derived from ENVISAT radar altimetry data. Simulated total water storage is assessed using monthly storage change values derived from GRACE data. The results show that the three precipitation datasets vary significantly in terms of magnitudes but generally produce a reasonable hydrograph throughout much of the basin, with the exception of the equatorial regions of the watershed. The satellite datasets provide unreasonably high values for specific periods (e.g. all three in Oct–Nov; only CMORPH and PERSIANN in Mar–Apr) in the equatorial regions. Overall, TRMM (3B42) provides the best spatial and temporal distributions and magnitudes or rainfall based on the assessment measures used here. Both CMORPH and PERSIANN tend to overestimate magnitudes, especially in the equatorial regions of the Basin. Copyright © 2011 John Wiley & Sons, Ltd.
Integrated cave drip monitoring for epikarst recharge estimation in a dry Mediterranean area, Sif Cave, Israel
Authors: Sheffer Nathan A. , Cohen Moty , Morin Efrat , Grodek Tamir , Gimburg Alex , Magal Einat , Gvirtzman Haim , Nied Manuela , Isele Daniel , Frumkin Amos
Published: February 2011

Understanding recharge mechanisms and controls in karst regions is extremely important for managing water resources because of the dynamic nature of the system. The objective of this study was to evaluate water percolation through epikarst by monitoring water flow into a cave and conducting artificial irrigation and tracer experiments, at Sif Cave in Wadi Sussi, Israel from 2005 through 2007.

The research is based on continuous high‐resolution direct measurements of both rainfall and water percolation in the cave chamber collected by three large PVC sheets which integrate drips from three different areas (17, 46, and 52 m2). Barrels equipped with pressure transducers record drip rate and volume for each of the three areas. The combined measured rainfall and cave data enables estimation of recharge into the epikarst and to better understand the relationship of rainfall‐recharge. Three distinct types of flow regimes were identified: (1) ‘Quick flow’ through preferential flow paths (large fractures and conduits); (2) ‘Intermediate flow’ through a secondary crack system; and (3) ‘Slow flow’ through the matrix. A threshold of ∼100 mm of rain at the beginning of the rainy season is required to increase soil water content allowing later rainfall events to percolate deeper through the soil and to initiate dripping in the cave. During winter, as the soil water content rises, the lag time between a rain event and cave drip response decreases. Annual recharge (140–160 mm in different areas in the cave) measured represents 30–35% of annual rainfall (460 mm). Copyright © 2011 John Wiley & Sons, Ltd.
Lake Ladoga ice phenology: Mean condition and extremes during the last 65 years
Authors: Karetnikov Sergey , Naumenko Mikhail
Published: February 2011

Winter conditions play an important role for the largest lake in Europe—Lake Ladoga. The ice cover lasts for 171 ± 3 days on average from the early November until the mid‐May. We investigated the ice regime of Lake Ladoga using a constructed ice database of aircraft surveys and satellite images. More than 1250 surveys of the lake's ice cover from 1943 to 2010 were collected and analysed to determine mean and extreme ice conditions for winters of different types of severity. The time series of ice cover percentage over the lake was plotted. On average, 18 observational ice charts were made every winter. Individual ice phenology records show considerable year‐to‐year variation. For this reason, records typically have been combined and analysed as groups (categories). Extremely cold winters were determined as winters with complete ice cover that lasts more than three months which is approximately 90% quartiles from all winters with complete ice cover. The lake surface was completely covered with ice for more than three months during 5 seasons. Extremely warm winters when the maximum ice cover was less than 70% of the lake area occurred during 5 seasons as well. A basic relationship between the winter severity as winter maximum of accumulated freezing degree‐days (AFDD) and the earlier derived Relative Ice Cover Index (RICI) was established. We have used teleconnection indices such as North Atlantic Oscillations (NAO) and Arctic Oscillation (AO) for the period from October to May for estimation of different types of Lake Ladoga's ice conditions. The AO index in winter months and local winter maximum of AFDD explained much of the interannual variation in ice cover. Copyright © 2011 John Wiley & Sons, Ltd.
Changes to sediment sources following wildfire in a forested upland catchment, southeastern Australia
Authors: Smith Hugh G. , Sheridan Gary J. , Lane Patrick N. J. , Noske Philip J. , Heijnis Henk
Published: February 2011

Few investigations link post‐fire changes to sediment sources and erosion processes with sediment yield response at the catchment scale. This linkage is essential if downstream impacts on sediment transport after fire are to be understood in the context of fire effects across different forest environments. In this study, we quantify changing source contributions to fine sediment (<63 µm) exported from a eucalypt forest catchment (136 ha) burnt by wildfire. The study catchment is one of a pair of research catchments located in the East Kiewa River valley in southeastern Australia that have been the subject of a research program investigating wildfire effects on runoff, erosion, and catchment sediment/nutrient exports. This previous research provided the opportunity to couple insights gained from a range of measurement techniques with the application of fallout radionuclides 137Cs and 210Pbex to trace sediment sources. It was found that hillslope surface erosion dominated exports throughout the 3·5‐year post‐fire measurement period. During this time there was a pronounced decline in the proportional surface contribution from close to 100% in the first six months to 58% in the fourth year after fire. Over the study period, hillslope surface sources accounted for 93% of the fine sediment yield from the burnt catchment. The largest decline in the hillslope contribution occurred between the first and second years after fire, which corresponded with the previously reported large decline in sediment yield, breakdown of water repellency in burnt soils, substantial reduction in hillslope erodibility, and rapid surface vegetation recovery. Coupling the information on sediment sources with hillslope process measurements indicated that only a small proportion of slopes contributed sediment to the catchment outlet, with material derived from near‐channel areas dominating the post‐fire catchment sediment yield response. Copyright © 2011 John Wiley & Sons, Ltd.
Roles of genipin crosslinking and biomolecule conditioning in collagen‐based biopolymer: Potential for vascular media regeneration
Authors: Madhavan Krishna , Belchenko Dmitry , Tan Wei
Published: February 2011

The vascular media, a layer of the blood vessel wall containing smooth muscle cells (SMCs), are often the target functional tissue in the construction of artificial vessel. It contributes to mechanical properties and biological functions of vessels. The present study aimed to study effects of crosslinking and biomolecule conditions in the development of mechanically strong and stable, biologically functional constructs with potential for vascular media regeneration. Genipin was used to crosslink collagen–chitosan–elastin (CCE) constructs. Results revealed that mechanical strength, stiffness, and stability of CCE constructs significantly increased with genipin concentration, but crosslinking significantly inhibited SMC contraction of and invasion in gel constructs. No contraction or invasion was observed in those crosslinked with genipin at 5 mM or above. attenuated total reflectance Fourier transform infrared results showed crosslinking changed functional groups on CCE depending on genipin concentration. To enhance biological activities on crosslinked constructs, soluble molecule factors were incorporated, and their effects on SMC activities were evaluated. These conditions include heparin, platelet‐derived transforming growth factor (PDGF), high‐concentrated fetal bovine serum (h‐FBS), a mixture of heparin and PDGF, and a mixture of h‐FBS and PDGF. The h‐FBS and PDGF mixture was found to stimulate a 3.2‐fold increase in SMC contraction of the crosslinked gels. It was also found that PDGF and h‐FBS, separately and in combination, induced SMC invasion in the crosslinked gels, while heparin attenuated PDGF‐induced SMC invasion. Our study suggests that designing high‐performance acellular constructs to encourage tissue regeneration should use a combination of crosslinking condition and biomolecule factor, striking a balance between mechanical properties and biological functions. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2011.
The influence of surface energy of titanium‐zirconium alloy on osteoblast cell functions in vitro
Authors: Sista Subhash , Wen Cui'e , Hodgson Peter D. , Pande Gopal
Published: February 2011

The success of an implant used for bone regeneration and repair is determined by the events that take place at the cell–material interface. An understanding of these interactions in vitro gives insights into the formulation of ideal conditions for their effective functioning in vivo. Thus, it is not only important to understand the physico‐chemical properties of the materials but, also necessary to assess the cellular responses to them to determine their long‐term stability and efficacy as implants. In the present study, we have compared the physico‐chemical and biological properties of titanium (Ti) and two Ti‐based alloys, namely: Ti‐ Zirconium (TiZr) and Ti‐Niobium (TiNb). The morphology, chemical analysis, surface roughness, and contact angle measurements of the alloys were assessed by scanning electron microscopy (SEM), X‐ray photoelectron spectroscopy (XPS), profilometer, and contact angle goniometer, respectively whereas the biological properties of the materials were evaluated by measuring the adhesion, proliferation, and differentiation of MC3T3‐E1 osteoblast cells on the surfaces of these alloys. Our results indicate that the biological properties of osteoblasts were better on TiZr surface than on TiNb surface. Furthermore, the surface energy and substrate composition influenced the superior biological activity of the TiZr alloy. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2011.
Structure and properties of biomedical films prepared from aqueous and acidic silk fibroin solutions
Authors: Rajkhowa Rangam , Levin Brett , Redmond Sharon L. , Li Lu Hua , Wang Lijing , Kanwar Jagat R. , Atlas Marcus D. , Wang Xungai
Published: February 2011

Silk fibroin films are promising materials for a range of biomedical applications. To understand the effects of casting solvents on film properties, we used water (W), formic acid (FA), and trifluoroacetic acid (TFA) as solvents. We characterized molecular weight, secondary structure, mechanical properties, and degradation behavior of cast films. Significant degradation of fibroin was observed for TFA‐based film compared to W and TA‐based films when analyzed by SDS–PAGE. Fibroin degradation resulted in a significant reduction in tensile strength and modulus of TFA‐based films. Compared to water, TFA‐based films demonstrated lower water solubility (19.6% vs. 62.5% in 12 h) despite having only a marginal increase in their β‐sheet content (26.9% vs. 23.7%). On the other hand, FA‐based films with 34.3% β‐sheet were virtually water insoluble. Following solubility treatment, β‐sheet content in FA‐based films increased to 50.9%. On exposure to protease XIV, water‐annealed FA‐based films lost 74% mass in 22 days compared to only 30% mass loss by ethanol annealed FA films. This study demonstrated that a small variation in the β‐sheet percentage and random coil conformations resulted in a significant change in the rates of enzymatic degradation without alteration to their tensile properties. The film surface roughness changed with the extent of enzymatic hydrolysis. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2011.
Controlled curing of adhesive complex coacervates with reversible periodate carbohydrate complexes
Authors: Shao Hui , Weerasekare G. Mahika , Stewart Russell J.
Published: February 2011

Periodate oxidation of carbohydrates with vicinal hydroxyl groups and aromatic ortho‐dihydroxyphenyl groups has been employed extensively to initiate crosslinking or conjugation reactions in adhesive biomaterials. Periodate forms stable tridentate complexes with carbohydrates containing three appropriately configured hydroxyls, such as 1,2‐O‐isopropylidene‐a‐D‐glucofuranose, that are not appreciably oxidized relative to carbohydrates with vicinal hydroxyls and ortho‐dihydroxyphenyl groups. In the presence of 1,2‐O‐Isopropylidene‐a‐D‐glucofuranose the rate of periodate oxidation of dihydroxy containing compounds is controlled by the rates of association and dissociation of the periodate‐carbohydrate complex. By varying the ratio of 1,2‐O‐isopropylidene‐a‐D‐glucofuranose to periodate the curing rate of adhesive complex coacervates was varied over a wide range. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2011.
Mortality risk for operated and nonoperated vertebral fracture patients in the medicare population
Authors: Edidin Avram Allan , Ong Kevin L , Lau Edmund , Kurtz Steven M
Published: February 2011

Vertebral compression fractures (VCFs) are associated with increased mortality risk, but the association between surgical treatment and survivorship is unclear. We evaluated the mortality risk for VCF patients undergoing conservative treatment (nonoperated), kyphoplasty, and vertebroplasty. Survival of VCF patients in the 100% U.S. Medicare data set (2005–2008) was estimated by the Kaplan-Meier method, and the differences in mortality rates at up to 4 years were assessed by Cox regression (adjusted for comorbidities) between operated and nonoperated patients and between kyphoplasty and vertebroplasty patients. An instrumental variables analysis was used to evaluate mortality-rate difference between kyphoplasty and vertebroplasty patients. A total of 858,978 VCF patients were identified, including 119,253 kyphoplasty patients and 63,693 vertebroplasty patients. At up to 4 years of follow-up, patients in the operated cohort had a higher adjusted survival rate of 60.8% compared with 50.0% for patients in the nonoperated cohort (p < .001) and were 37% less likely to die [adjusted hazard ratio (HR) = 0.63, p < .001]. The adjusted survival rates for VCF patients following vertebroplasty or kyphoplasty were 57.3% and 62.8%, respectively (p < .001). The relative risk of mortality for kyphoplasty patients was 23% lower than that for vertebroplasty patients (adjusted HR = 0.77, p < .001). Using physician preference as an instrument, the absolute difference in the adjusted survival rate at 3 years was 7.29% higher in patients receiving kyphoplasty than vertebroplasty (p < .001), compared with a crude absolute rate difference of 5.09%. This study established the mortality risk associated with VCFs diagnosed between 2005 and 2008 with respect to different treatment modalities for elderly patients in the entire Medicare population. © 2011 American Society for Bone and Mineral Research.
Regulation of RANKL-induced osteoclastogenesis by TGF-β through molecular interaction between Smad3 and Traf6
Authors: Yasui Tetsuro , Kadono Yuho , Nakamura Masaki , Oshima Yasushi , Matsumoto Takumi , Masuda Hironari , Hirose Jun , Omata Yasunori , Yasuda Hisataka , Imamura Takeshi , Nakamura Kozo , Tanaka Sakae
Published: February 2011

Previous studies have shown that transforming growth factor β (TGF-β) promotes receptor activator of nuclear factor-κB ligand (RANKL)–induced osteoclastogenesis. However, the underlying molecular mechanisms have not been elucidated. When TGF-β signals were blocked either by a specific inhibitor of TGF-β type 1 receptor kinase activity, SB431542, or by introducing a dominant-negative mutant of TGF-β type 2 receptor, RANKL-induced osteoclastogenesis was almost completely suppressed. Blockade of Smad signaling by overexpression of Smad7 or c-Ski markedly suppressed RANKL-induced osteoclastogenesis, and retroviral induction of an activated mutant of Smad2 or Smad3 reversed the inhibitory effect of SB431542. Immunoprecipitation analysis revealed that Smad2/3 directly associates with the TRAF6-TAB1-TAK1 molecular complex, which is generated in response to RANKL stimulation and plays an essential role in osteoclast differentiation. TRAF6-TAB1-TAK1 complex formation was not observed when TGF-β signaling was blocked. Analysis using deletion mutants revealed that the MH2 domain of Smad3 is necessary for TRAF6-TAB1-TAK1 complex formation, downstream signal transduction, and osteoclast formation. In addition, gene silencing of Smad3 in osteoclast precursors markedly suppressed RANKL-induced osteoclast differentiation. In summary, TGF-β is indispensable in RANKL-induced osteoclastogenesis, and the binding of Smad3 to the TRAF6-TAB1-TAK1 complex is crucial for RANKL-induced osteoclastogenic signaling. © 2011 American Society for Bone and Mineral Research.
Mangiferin: A xanthone attenuates mercury chloride induced cytotoxicity and genotoxicity in HepG2 cells
Authors: Kaivalya Mudholkar , Rao B. Nageshwar , Satish Rao B. S.
Published: February 2011

Mangiferin (MGN), a dietary C‐glucosylxanthone present in Mangifera indica, is known to possess a spectrum of beneficial pharmacological properties. This study demonstrates antigenotoxic potential of MGN against mercuric chloride (HgCl2) induced genotoxicity in HepG2 cell line. Treatment of HepG2 cells with various concentrations of HgCl2 for 3 h caused a dose‐dependent increase in micronuclei frequency and elevation in DNA strand breaks (olive tail moment and tail DNA). Pretreatment with MGN significantly (p < 0.01) inhibited HgCl2‐induced (20 µM for 30 h) DNA damage. An optimal antigenotoxic effect of MGN, both in micronuclei and comet assay, was observed at a concentration of 50 µM. Furthermore, HepG2 cells treated with various concentrations of HgCl2 resulted in a dose‐dependent increase in the dichlorofluorescein fluorescence, indicating an increase in the generation of reactive oxygen species (ROS). However, MGN by itself failed to generate ROS at a concentration of 50 µM, whereas it could significantly decrease HgCl2‐induced ROS. Our study clearly demonstrates that MGN pretreatment reduced the HgCl2‐induced DNA damage in HepG2 cells, thus demonstrating the genoprotective potential of MGN, which is mediated mainly by the inhibition of oxidative stress. © 2011 Wiley Periodicals, Inc. J Biochem Mol Toxicol 25:108–116 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/jbt.20366