bluuebunny/crossref_metadata_2025 huggingface dataset:
New Approaches for Education and Training in Veterinary Public Health: The SAPUVET Projects
Authors: Ortega Carmelo , Parilla Guillermo , De Balogh Katinka , Rosa Mauro De , Gimeno Olga , Estol Leopoldo , Dobosh Dora , Leguia Guillermo , Falcon Nestor , Fonseca Adolfo , Torres Miguel , Caballero Magaly , Quiros Jorge , Vilhena Manuela Clemente , Villamil Luis Carlos , Cediel Natalia , De Meneghi Daniele
Published: February 2011

Continued contact between humans and animals, in combination with the ever-increasing movement of human and animal populations that is one effect of globalization, contributes to the spread of diseases, often with detrimental effects on public health. This has led professionals involved in both animal health and public health to recognize veterinary public health (VPH) as a key area for their activities to address the human–animal interface. Veterinarians, a profession with major involvement in this field, are in need of specific knowledge and skills to prevent and control public-health problems. As a result, VPH must be directly integrated into veterinary educational programs. At present, only few veterinary schools have specific VPH programs; in most institutions, VPH does not feature as a specific subject in either undergraduate or post-graduate curricula. SAPUVET and SAPUVETNET II are network projects supported by the ALFA program of the European Union (EU). Their main objectives are to reach a common understanding between European and Latin American universities in the definition of the areas in which VPH is important in their respective countries, and to design a harmonized training program for veterinarians in VPH, by making use of new technological applications and innovative teaching methodologies. The elaboration of educational material in combination with case studies presenting real-life problems provides a basis to apply the knowledge acquired on VPH. It is envisaged that the material and modules developed during the two projects will be integrated into the veterinary curricula of the participating universities, as well as in other partner organizations.
Interactive Computerized Learning Program Exposes Veterinary Students to Challenging International Animal-Health Problems
Authors: Conrad Patricia A. , Hird Dave , Arzt Jonathan , Hayes Rick H. , Magliano Dave , Kasper Janine , Morfin Saul , Pinney Stephen
Published: February 2011

This article describes a computerized case-based CD-ROM (CD) on international animal health that was developed to give veterinary students an opportunity to “virtually” work alongside veterinarians and other veterinary students as they try to solve challenging disease problems relating to tuberculosis in South African wildlife, bovine abortion in Mexico, and neurologic disease in horses in Rapa Nui, Chile. Each of the three case modules presents, in a highly interactive format, a problem or mystery that must be solved by the learner. As well as acquiring information via video clips and text about the specific health problem, learners obtain information about the different countries, animal-management practices, diagnostic methods, related disease-control issues, economic factors, and the opinions of local experts. After assimilating this information, the learner must define the problem and formulate an action plan or make a recommendation or diagnosis. The computerized program invokes three principles of adult education: active learning, learner-centered education, and experiential learning. A medium that invokes these principles is a potentially efficient learning tool and template for developing other case-based problem-solving computerized programs. The program is accessible on the World Wide Web at <>. A broadband Internet connection is recommended, since the modules make extensive use of embedded video and audio clips. Information on how to obtain the CD is also provided.
The Entropy of Progressively Censored Samples
Authors: Abo-Eleneen Z. A.
Published: February 2011

In many life-testing and reliability studies, the experimenter might not always obtain complete information on failure times for all experimental units. Among the different censoring schemes, the progressive censoring scheme has received a considerable attention in the last few years. The aim of this paper is simplifying the entropy of progressively Type II censored samples. We propose an indirect approach using a decomposition of the entropy in progressively Type II censored samples to simplify the calculation. Some recurrence relations for the entropy in progressively Type II censored samples are derived to facilitate this calculation. An efficient computational method is derived that simplifies computation of the entropy in progressively Type II censored samples to a sum; entropy in collections order statistics. We compute the entropy in a collection of progressively Type II censored samples for some known distributions.
Filamentous Fungi in Drinking Water, Particularly in Relation to Biofilm Formation
Authors: Siqueira Virgínia M. , Oliveira Helena M. B. , Santos Cledir , Paterson R. Russell M. , Gusmão Norma B. , Lima Nelson
Published: February 2011

The presence of filamentous fungi in drinking water has become an area worthy of investigation with various studies now being published. The problems associated with fungi include blockage of water pipes, organoleptic deterioration, pathogenic fungi and mycotoxins. Fungal biofilm formation is a less developed field of study. This paper updates the topic and introduces novel methods on fungal biofilm analysis, particularly from work based in Brazil. Further recommendations for standard methodology are provided.
An Alternative View of Privacy on Facebook
Authors: Fuchs Christian
Published: February 2011

The predominant analysis of privacy on Facebook focuses on personal information revelation. This paper is critical of this kind of research and introduces an alternative analytical framework for studying privacy on Facebook, social networking sites and web 2.0. This framework is connecting the phenomenon of online privacy to the political economy of capitalism—a focus that has thus far been rather neglected in research literature about Internet and web 2.0 privacy. Liberal privacy philosophy tends to ignore the political economy of privacy in capitalism that can mask socio-economic inequality and protect capital and the rich from public accountability. Facebook is in this paper analyzed with the help of an approach, in which privacy for dominant groups, in regard to the ability of keeping wealth and power secret from the public, is seen as problematic, whereas privacy at the bottom of the power pyramid for consumers and normal citizens is seen as a protection from dominant interests. Facebook’s privacy concept is based on an understanding that stresses self-regulation and on an individualistic understanding of privacy. The theoretical analysis of the political economy of privacy on Facebook in this paper is based on the political theories of Karl Marx, Hannah Arendt and Jürgen Habermas. Based on the political economist Dallas Smythe’s concept of audience commodification, the process of prosumer commodification on Facebook is analyzed. The political economy of privacy on Facebook is analyzed with the help of a theory of drives that is grounded in Herbert Marcuse’s interpretation of Sigmund Freud, which allows to analyze Facebook based on the concept of play labor (= the convergence of play and labor).
Material Binding Peptides for Nanotechnology
Authors: Seker Urartu Ozgur Safak , Demir Hilmi Volkan
Published: February 2011

Remarkable progress has been made to date in the discovery of material binding peptides and their utilization in nanotechnology, which has brought new challenges and opportunities. Nowadays phage display is a versatile tool, important for the selection of ligands for proteins and peptides. This combinatorial approach has also been adapted over the past decade to select material-specific peptides. Screening and selection of such phage displayed material binding peptides has attracted great interest, in particular because of their use in nanotechnology. Phage display selected peptides are either synthesized independently or expressed on phage coat protein. Selected phage particles are subsequently utilized in the synthesis of nanoparticles, in the assembly of nanostructures on inorganic surfaces, and oriented protein immobilization as fusion partners of proteins. In this paper, we present an overview on the research conducted on this area. In this review we not only focus on the selection process, but also on molecular binding characterization and utilization of peptides as molecular linkers, molecular assemblers and material synthesizers.
Special Issue: Nano-Catalysts and Nano-Technologies for Green Organic Synthesis
Authors: Nacci Angelo , Cioffi Nicola
Published: February 2011

Catalysis by transition-metal nanoparticles has undergone an explosive growth during the past decade. This special issue presents the general trends in the current research in this field, the present situation concerning scope and limitations, as well as the future perspectives. Original contributions are also presented on the applications of nano-catalysts to the green synthesis.
Electrospun Nanofibrous Materials for Neural Tissue Engineering
Authors: Lee Yee-Shuan , Livingston Arinzeh Treena
Published: February 2011

The use of biomaterials processed by the electrospinning technique has gained considerable interest for neural tissue engineering applications. The tissue engineering strategy is to facilitate the regrowth of nerves by combining an appropriate cell type with the electrospun scaffold. Electrospinning can generate fibrous meshes having fiber diameter dimensions at the nanoscale and these fibers can be nonwoven or oriented to facilitate neurite extension via contact guidance. This article reviews studies evaluating the effect of the scaffold’s architectural features such as fiber diameter and orientation on neural cell function and neurite extension. Electrospun meshes made of natural polymers, proteins and compositions having electrical activity in order to enhance neural cell function are also discussed.
Approaches towards the synthesis of 5-aminopyrazoles
Authors: Aggarwal Ranjana , Kumar Vinod , Kumar Rajiv , Singh Shiv P
Published: February 2011

The biological and medicinal properties of 5-aminopyrazoles have prompted enormous research aimed at developing synthetic routes to these heterocyles. This review focuses on the biological properties associated with this system. Various synthetic methods developed up to 2010 for these compounds are described, particularly those that involve the reactions of β-ketonitriles, malononitrile, alkylidenemalononitriles and their derivatives with hydrazines, as well as some novel miscellaneous methods.
University of Alberta Undergraduate Student and Alumni Pharmacist Mentorship Pilot Project
Authors: Lopatka Harold , Hickson Clive , Legaarden Terry
Published: February 2011

Background:

The value of mentoring is recognized in many fields, including pharmacy, as a means for one person (mentor) to help another person (protegé) enhance his or her growth, knowledge and skills. The University of Alberta Faculty of Pharmacy and the Pharmacy Alumni Association conducted an 8-month mentorship pilot project involving pharmacy undergraduate students and alumni pharmacists. The focus was to assist students transitioning into the pharmacy workforce by providing guidance and advice from pharmacist mentors.

Methods:

A prototype mentorship model was developed. The model consisted of recruitment and matching processes and multiple structured and unstructured communication sessions (education and relationship-building). Seven student protegés and 7 licensed Alberta pharmacists participated in the pilot throughout the 2007–08 academic year. The formal evaluation was based on document reviews and participant interviews.

Results:

The key findings included: participants were very positive about the pilot program activities; both protegés and mentors would recommend participation to colleagues; the ideal year for participation was the third year in the pharmacy undergraduate program; the most beneficial pieces of advice were about change associated with early career development; 5 of 7 mentor/protegé pairs planned to continue or were actually continuing communications; e-mail was the most efficient communication; finding the time to communicate was the major barrier.

Discussion:

The results from the pilot provided preliminary evidence that pharmacy students have similar mentorship needs as students in other disciplines and that a formal mentorship model can address these needs. The students had career-related and personal questions and interests that were addressed by the alumni pharmacist mentors. The mentorship model had sufficient processes and structure to build and maintain relationships and to satisfy mentorship needs.

Conclusion:

The pilot demonstrated that a pharmacy mentorship model can be successfully established and be of benefit to participants and potentially to pharmacy practice. Based on the findings, an expanded version of the program was implemented in the fall 2009 academic term.
Experience with an Adherence Assessment Form
Authors: McLean William , Sparrow Linda , Stann Darcy
Published: February 2011

Background:

Nonadherence is so common that the majority of patients taking chronic medications will eventually stop their medication on their own. Pharmacists are in a position to intervene to improve adherence; however, many do not. Such intervention would ideally be accomplished in a total pharmaceutical care approach; however, many pharmacists feel they do not have the time for such interventions. We propose the use of an adherence assessment form which the patient would complete to save pharmacist time; the pharmacist could then react to issues identified in the form.

Purpose:

The objective of this study was to determine the acceptability of such a form to patients and to dispensary staff, and its potential for impact on adherence.

Methods:

The author recruited 2 regional groups of pharmacies with pharmacy interns/students, 4 in Hamilton and 15 in Edmonton. Patients presenting with new prescriptions were asked by the intern or the staff to participate via a consent form. Patients completed the adherence assessment form while they waited for their prescription. The pharmacist then intervened on adherence issues identified in the questionnaire. The patient completed a patient satisfaction survey. The pharmacist or the assistant was asked to complete a pharmacy satisfaction survey.

Results:

A total of 200 patients, 111 in Hamilton and 89 in Edmonton, completed the process. Analysis of patient responses revealed that most patients expect benefits from their medication and would like more information; 2/3 found that the assessment form led to an informative discussion; 1/3 found that it brought up issues they had not thought about; over half learned a lot about their new medication; and over half said that as a result of the dialogue, they will know what do about side effects; 1/5 said they would be more motivated about their health. Analysis from the pharmacies revealed that over half of the pharmacies believed the form improved comprehension of the medication regimen; over half believed it facilitated more consultation for patients; over half found greater satisfaction by patients for their services and 1/3 felt it frequently changed patient outcomes. Despite all this, 2/3 of pharmacies said that the form should not be routinely used, as it did not save pharmacists any time.

Conclusion:

It was concluded that the form was acceptable to patients and pharmacies and showed sufficient potential impact to warrant a study of its influence on adherence measures.
Towards inverse modeling of cloud-aerosol interactions – Part 1: A detailed response surface analysis
Authors: Partridge D. G. , Vrugt J. A. , Tunved P. , Ekman A. M. L. , Gorea D. , Sorooshian A.
Published: February 2011

Abstract. This paper explores the feasibility of inverse modeling to determine cloud-aerosol interactions using a pseudo-adiabatic cloud-parcel model. Two-dimensional plots of the objective function, containing the difference between the measured and model predicted droplet size distribution, are presented for selected pairs of cloud parcel model parameters. From these response surfaces it is shown that the "cloud-aerosol" inverse problem is particularly difficult to solve due to significant parameter interaction, presence of multiple regions of attractions, numerous local optima, and considerable parameter insensitivity. Sensitivity analysis is performed to help select an appropriate objective function that maximizes information retrieval from the measured droplet size distribution to help identify the unknown model parameters. The identifiability of the model parameters will be dependent on the choice of the objective function; including the interstitial aerosol will aid the calibration of parameters describing the smaller aerosol mode. Cloud parcel models that employ a moving-centre based calculation of the droplet size distribution require both the X and Y components of the dN/dlogdp size distribution function to be explicitly included in the objective function. Other possible improvements identified include an improved representation of the resolution of the region of the size spectrum associated with droplet activation within cloud parcel models, and further development of fixed-sectional cloud models that minimize numerical diffusion. Despite these developments, powerful search algorithms remain necessary to efficiently explore the parameter space and successfully solve the cloud-aerosol inverse problem.
Atmospheric boundary layer characteristics over the Pearl River Delta, China during summer 2006: measurement and model results
Authors: Fan S. J. , Fan Q. , Yu W. , Luo X. Y. , Wang B. M. , Song L. L. , Leong K. L.
Published: February 2011

Abstract. Atmospheric conditions are often connected with the occurrence of high pollution episodes especially in urban areas. As part of the PRIDE-PRD2006 intensive campaign, atmospheric boundary layer (ABL) measurements were carried out at Qingyuan, Panyu and Xinken in the Pearl River Delta (PRD) from 1 July to 30 July of 2006. It was found that in summer, the surface winds in PRD are more controlled by the south, and there usually is vertical wind shear at the height of 800 m or so, therefore, PRD is often influenced by the tropical cyclone/typhoon. The subsidence and precipitation from a tropical cyclone will affect the air quality of PRD. Under the subsidence, the wind speed in ABL and the height of ABL will decrease and result in high level concentrations. When the background wind speed is small or calm, the wind profile at Panyu and Xinken change dramatically with height, which is perhaps caused by the local circulations, such as the sea land breeze. For more understanding about the ABL of PRD, the simulations by the WRF mesoscale model were used to analyse the ABL characteristics in PRD. From three kinds of weather condition simulations (subsidence days, rainy days and sunny days) by WRF model, it was found that the simulated temperature, wind fields in these three cases were moderately consistent with the measurements. The results show that the diurnal variation of ABL in subsidence days and sunny days are obvious, but the diurnal variation of ABL on rainy days is not obvious. The ABL is obviously affected by the local circulation and the features of ABL are different in various stations. A simulation focus on high pollution episode during the subsidence days from 12–15 July 2006, occurred under high pressure conditions, accompanied by a tropical cyclone "Bilis". Comparing the simulated vertical wind fields and temperature structure with the ABL measurements at Xinken, Panyu and Qingyuan station, it was found that, the modelled and measured atmospheric fields reveal that there are two different kinds of ABL characteristics in PRD: when the surface winds in PRD were light or almost calm, the local circulation was dominated, such as the sea-land breeze at Xinken station and the mountain-valley circulation at Qingyuan station. When the surface winds were strong, the stations were under the same background weather system and the wind directions were almost the same. Furthermore, the modelled results also suggest that the high Air Pollutant index (API) episode was caused predominately by subsidence.
Measurements of the timescales for the mass transfer of water in glassy aerosol at low relative humidity and ambient temperature
Authors: Tong H.-J. , Reid J. P. , Bones D. L. , Luo B. P. , Krieger U. K.
Published: February 2011

Abstract. The influence of glassy states and highly viscous solution phases on the timescale of aerosol particle equilibration with water vapour is examined. In particular, the kinetics of mass transfer of water between the condensed and gas phases has been studied for sucrose solution droplets under conditions above and below the glass transition relative humidity (RH). At RHs above the glass transition, sucrose droplets are shown to equilibrate on a timescale comparable to the change in environmental conditions. Below the glass transition, the timescale for mass transfer is shown to be extremely slow, with particles remaining in a state of disequilibrium even after timescales of more than 10000 s. A phenomenological approach for quantifying the time response of particle size is used to illustrate the influence of the glassy aerosol state on the kinetics of mass transfer of water: the time is estimated for the droplet to reach the halfway point from an initial state towards a disequilibrium state at which the rate of size change decreases below 1 nm every 10000 s. This half-time increases above 1000 s once the particle can be assumed to have formed a glass. The measurements are shown to be consistent with kinetic simulations of the slow diffusion of water within the particle bulk. Similar behaviour is observed for binary aqueous raffinose solution droplets consistent with the influence of a glass transition on mass transfer. Mixed component droplets of sucrose/sodium chloride/water also show slow equilibration at low RH, illustrating the importance of understanding the role of the bulk solution viscosity on the rate of mass transfer with the gas phase, even under conditions that may not lead to the formation of a glass.
Atmospheric chemistry of carboxylic acids: microbial implication versus photochemistry
Authors: Vaïtilingom M. , Charbouillot T. , Deguillaume L. , Maisonobe R. , Parazols M. , Amato P. , Sancelme M. , Delort A.-M.
Published: February 2011

Abstract. Clouds are multiphasic atmospheric systems in which the dissolved organic compounds, dominated by carboxylic acids, are subject to multiple chemical transformations in the aqueous phase. Among them, solar radiation, by generating hydroxyl radicals (•OH), is considered as the main catalyzer of the reactivity of organic species in clouds. We investigated to which extent the active biomass existing in cloud water represents an alternative route to the chemical reactivity of carboxylic acids. Pure cultures of seventeen bacterial strains (Arthrobacter, Bacillus, Clavibacter, Frigoribacterium, Pseudomonas, Sphingomonas and Rhodococcus), previously isolated from cloud water and representative of the viable community of clouds were first individually incubated in two artificial bulk cloud water solutions at 17 °C and 5 °C. These solutions mimicked the chemical composition of cloud water from "marine" and "continental" air masses, and contained the major carboxylic acids existing in the cloud water (i.e. acetate, formate, succinate and oxalate). The concentrations of these carboxylic compounds were monitored over time and biodegradation rates were determined. In average, they ranged from 2 ×10−19 for succinate to 1 × 10−18 mol cell−1 s−1 for formate at 17 °C and from 4 × 10−20 for succinate to 6 × 10−19 mol cell−1 s−1 for formate at 5 °C, with no significant difference between "marine" and "continental" media. In parallel, irradiation experiments were also conducted in these two artificial media to compare biodegradation and photodegradation of carboxylic compounds. To complete this comparison, the photodegradation rates of carboxylic acids by •OH radicals were calculated from literature data. Inferred estimations suggested a significant participation of microbes to the transformation of carboxylic acids in cloud water, particularly for acetate and succinate (up to 90%). Furthermore, a natural cloud water sample was incubated (including its indigenous microflora); the rates of biodegradation were determined and compared to the photodegradation rates involving •OH radicals. The biodegradation rates in "natural" and "artificial" cloud water were in the same order of magnitude; this confirms the significant role of the active biomass in the aqueous reactivity of clouds.
Future emissions from oil, gas, and shipping activities in the Arctic
Authors: Peters G. P. , Nilssen T. B. , Lindholt L. , Eide M. S. , Glomsrød S. , Eide L. I. , Fuglestvedt J. S.
Published: February 2011

Abstract. The Arctic sea-ice is retreating faster than predicted by climate models and could become ice free during summer this century. The reduced sea-ice extent may effectively "unlock" the Arctic Ocean to increased human activities such as transit shipping and expanded oil and gas production. Travel time between Europe and the north Pacific Region can be reduced by up to 50% with low sea-ice levels and the use of this route could increase substantially as the sea-ice retreats. Oil and gas activities already occur in the Arctic region and given the large undiscovered petroleum resources increased activity could be expected with reduced sea-ice. We use a detailed global energy market model and a bottom-up shipping model with a sea-ice module to construct emission inventories of Arctic shipping and petroleum activities in 2030 and 2050. The emission inventories are on a 1× 1 degree grid and cover both short-lived pollutants and ozone pre-cursors (SO2, NOx, CO, NMVOC, BC, OC) and the long-lived greenhouse gases (CO2, CH4, N2O). We find rapid growth in transit shipping due to increased profitability with the shorter transit times compensating for increased costs in traversing areas of sea-ice. Oil and gas production remains relatively stable leading to reduced emissions from emission factor improvements. The location of oil and gas production moves into locations requiring more ship transport relative to pipeline transport, leading to rapid emissions growth from oil and gas transport via ship. Our emission inventories for the Arctic region will be used as input into chemical transport, radiative transfer, and climate models to quantify the role of Arctic activities in climate change compared to similar emissions occurring outside of the Arctic region.
Errors in GNSS radio occultation data: relevance of the measurement geometry and obliquity of profiles
Authors: Foelsche U. , Syndergaard S. , Fritzer J. , Kirchengast G.
Published: February 2011

Abstract. Atmospheric profiles retrieved from GNSS (Global Navigation Satellite System) radio occultation (RO) measurements are increasingly used to validate other measurement data. For this purpose it is important to be aware of the characteristics of RO measurements. RO data are frequently compared with vertical reference profiles, but the RO method does not provide vertical scans through the atmosphere. The average elevation angle of the tangent point trajectory (which would be 90° for a vertical scan) is about 40° at altitudes above 70 km, decreasing to about 25° at 20 km and to less than 5° below 3 km. In an atmosphere with high horizontal variability we can thus expect noticeable representativeness errors if the retrieved profiles are compared with vertical reference profiles. We have performed an end-to-end simulation study using high-resolution analysis fields (T799L91) from the European Centre for Medium-Range Weather Forecasts (ECMWF) to simulate a representative ensemble of RO profiles via high-precision 3-D ray tracing. Thereby we focused on the dependence of systematic and random errors on the measurement geometry, specifically on the incidence angle of the RO measurement rays with respect to the orbit plane of the receiving satellite, also termed azimuth angle, which determines the obliquity of RO profiles. We analyzed by how much errors are reduced if the reference profile is not taken vertical at the mean tangent point but along the retrieved tangent point trajectory (TPT) of the RO profile. The exact TPT can only be determined by performing ray tracing, but our results confirm that the retrieved TPT – calculated from observed impact parameters – is a very good approximation to the "true" one. Systematic and random errors in RO data increase with increasing azimuth angle, less if the TPT is properly taken in to account, since the increasing obliquity of the RO profiles leads to an increasing sensitivity to departures from horizontal symmetry. Up to an azimuth angle of 30°, however, this effect is small, even if the RO profiles are assumed to be vertical. For applications requiring highest accuracy and precision it is advisable to exclude RO profiles with ray incidence angles beyond an azimuth of 50°. Errors in retrieved atmospheric profiles decrease significantly, by up to a factor of 2, if the RO data are exploited along the retrieved TPT. The tangent point trajectory of RO profiles should therefore be exploited whenever this is possible.
Evaluating the assumptions of surface reflectance and aerosol type selection within the MODIS aerosol retrieval over land: the problem of dust type selection
Authors: Mielonen T. , Levy R. C. , Aaltonen V. , Komppula M. , de Leeuw G. , Huttunen J. , Lihavainen H. , Kolmonen P. , Lehtinen K. E. J. , Arola A.
Published: February 2011

Abstract. Aerosol Optical Depth (AOD) and Ångström exponent (AE) values derived with the MODIS retrieval algorithm over land (Collection 5) are compared with ground based sun photometer measurements at eleven sites spanning the globe. Although, in general, total AOD compares well at these sites (R2 values generally over 0.8), there are cases (from 2 to 67% of the measurements depending on the site) where MODIS clearly retrieves the wrong spectral dependence, and hence, an unrealistic AE value. Some of these poor AE retrievals are due to the aerosol signal being too small (total AOD < 0.3) but in other cases the AOD should have been high enough to derive accurate AE. However, in these cases, MODIS indicates AE values close to 0.6 and zero fine model weighting (FMW), i.e. dust model provides the best fitting to the MODIS observed reflectance. Yet, according to evidence from the collocated sun photometer measurements and backtrajectory analyses, there should be no dust present. This indicates that the assumptions about aerosol model and surface properties made by the MODIS algorithm may have been incorrect. Here we focus on problems related to parameterization of the land-surface optical properties in the algorithm, in particular the relationship between the surface reflectance at 660 and 2130 nm. The retrieval assumes that there is a linear equation that relates the reflectance in these two channels, with the value of the slope (slope660/2130) determined, in part, by the infrared Normalized Difference Vegetation Index, (NDVISWIR). However, the assumed dependence of the slope on the NDVISWIR is not supported by a MODIS based surface albedo climatology. The use of a modified relationship based on the albedo data improves the AE retrieval at the studied sites. The increase in the AE agreement fraction between MODIS and AERONET measurements is between 3 and 22 percentage units depending on the site. These results indicate that the surface reflectance assumptions, especially the slope660/2130 in the MODIS algorithm is the major reason for the inaccurate AE values and the flawed aerosol model combining in the retrieval. However, at some of these sites, the new relationship slightly reduces the correlation between the MODIS and AERONET AOD. This decrease indicates that the combination of the assumed surface and aerosol properties still do not match the actual properties under investigation.
Detection of pore space in CT soil images using artificial neural networks
Authors: Cortina-Januchs M. G. , Quintanilla-Dominguez J. , Vega-Corona A. , Tarquis A. M. , Andina D.
Published: February 2011

Abstract. Computed Tomography (CT) images provide a non-invasive alternative for observing soil structures, particularly pore space. Pore space in soil data indicates empty or free space in the sense that no material is present there except fluids such as air, water, and gas. Fluid transport depends on where pore spaces are located in the soil, and for this reason, it is important to identify pore zones. The low contrast between soil and pore space in CT images presents a problem with respect to pore quantification. In this paper, we present a methodology that integrates image processing, clustering techniques and artificial neural networks, in order to classify pore space in soil images. Image processing was used for the feature extraction of images. Three clustering algorithms were implemented (K-means, Fuzzy C-means, and Self Organising Maps) to segment images. The objective of clustering process is to find pixel groups of a similar grey level intensity and to organise them into more or less homogeneous groups. The segmented images are used for test a classifier. An Artificial Neural Network is characterised by a great degree of modularity and flexibility, and it is very efficient for large-scale and generic pattern recognition applications. For these reasons, an Artificial Neural Network was used to classify soil images into two classes (pore space and solid soil). Our methodology shows an alternative way to detect solid soil and pore space in CT images. The percentages of correct classifications of pore space of the total number of classifications among the tested images were 97.01%, 96.47% and 96.12%.
Influence of seasonal monsoons on net community production and CO2 in subtropical Hong Kong coastal waters
Authors: Yuan X.-C. , Yin K. , Cai W.-J. , Ho A. Y. , Xu J. , Harrison P. J.
Published: February 2011

Abstract. Data from seven cruises in three different environments including the Pearl River estuary, sewage discharge outfall, and eastern coastal/shelf waters were used to examine the seasonal variations in net community production (NCP) and the biologically active gases O2 and CO2. In the winter dry season, when monsoon-induced downwelling was dominant, NCP was negative (−84 ± 50 mmol C m−2 d−1) in all three regions. The negative NCP corresponded to O2 influxes of 100 ± 50 mmol O2 m−2 d−1 and CO2 effluxes of 24 ± 10 mmol C m−2 d−1. In the summer wet season, when upwelling brought the deep oceanic waters to the coast due to the southwest monsoonal winds, there was a 2 to 15-fold increase in integrated primary production (IPP) compared to winter. The increase in IPP was likely due to the favorable conditions such as stratification and the nutrient inputs from upwelled waters and the Pearl River estuary. NCP in the mixed layer reached up to 110 ± 48 mmol C m−2 d−1 in the wet season. However, accompanying the high positive NCP, we observed an O2 influx of 100 ± 60 mmol O2 m−2 d−1 and CO2 efflux of 21 ± 15 mmol C m−2 d−1. The contradictory observation of positive NCP and CO2 release and O2 uptake in the mixed layer could be explained by the influence of the southwest monsoon-induced upwelling along with the influence of the Pearl River, as the upwelling brought cold, low dissolved oxygen (DO, 160 ± 30 μM) and high dissolved inorganic carbon (DIC, 1960 ± 100 μatm) water to the surface in the wet season. Hence, the subtropical Hong Kong coastal waters are generally a CO2 source due to the monsoonal influence during both the dry-heterotrophic and wet-autotrophic seasons.
Assessment of the importance of dissimilatory nitrate reduction to ammonium for the terrestrial nitrogen cycle
Authors: Rütting T. , Boeckx P. , Müller C. , Klemedtsson L.
Published: February 2011

Abstract. The nitrogen (N) cycle contains two different processes of dissimilatory nitrate (NO3−) reduction, denitrification and dissimilatory NO3− reduction to ammonium (DNRA). While there is general agreement that the denitrification process takes place in many soils, the occurrence and importance of DNRA is generally not considered. Two approaches have been used to investigate DNRA in soil, (1) microbiological techniques to identify soil microorganisms capable of DNRA and (2) 15N tracing to elucidate the occurrence of DNRA and to quantify gross DNRA rates. There is evidence that many soil bacteria and fungi have the ability to perform DNRA. Redox status and C/NO3− ratio have been identified as the most important factors regulating DNRA in soil. 15N tracing studies have shown that gross DNRA rates can be a significant or even a dominant NO3− consumption process in some ecosystems. Moreover, a link between heterotrophic nitrification and DNRA provides an alternative pathway of ammonium (NH4+) production to mineralisation. Numerical 15N tracing models can be particularly useful when investigating DNRA in the context of other N cycling processes. With this review we summarise the importance and current knowledge of this often overlooked NO3− consumption process within the terrestrial N cycle. We strongly encourage considering DNRA as a relevant soil N process in future N cycling investigations.
Application of Fourier Transform Infrared Spectroscopy (FTIR) for assessing biogenic silica sample purity in geochemical analyses and palaeoenvironmental research
Authors: Swann G. E. A. , Patwardhan S. V.
Published: February 2011

Abstract. The development of a rapid and non-destructive method to assess purity levels in samples of biogenic silica prior to geochemical/isotope analysis remains a key objective in improving both the quality and use of such data in environmental and palaeoclimatic research. Here a Fourier Transform Infrared Spectroscopy (FTIR) mass-balance method is demonstrated for calculating levels of contamination in cleaned sediment core diatom samples from Lake Baikal, Russia. Following the selection of end-members representative of diatoms and contaminants in the analysed samples, a mass-balance model is generated to simulate the expected FTIR spectra for a given level of contamination. By fitting the sample FTIR spectra to the modelled FTIR spectra and calculating the residual spectra, the optimum best-fit model and level of contamination is obtained. When compared to X-ray Fluorescence (XRF) the FTIR method portrays the main changes in sample contamination through the core sequence, permitting its use in instances where other, destructive, techniques are not appropriate. The ability to analyse samples of <1 mg enables, for the first time, routine analyses of small sized samples. Discrepancies between FTIR and XRF measurements can be attributed to FTIR end-members not fully representing all contaminants and problems in using XRF to detect organic matter external to the diatom frustule. By analysing samples with both FTIR and XRF, these limitations can be eliminated to accurately identify contaminated samples. Future, routine use of these techniques in palaeoenvironmental research will therefore significantly reduce the number of erroneous measurements and so improve the accuracy of biogenic silica/diatom based climate reconstructions.
Impact of North Atlantic – GIN Sea exchange on deglaciation evolution of Atlantic Meridional Overturning Circulation
Authors: Cheng J. , Liu Z. , He F. , Otto-Bliesner B. L.
Published: February 2011

Abstract. The Bølling-Allerød (BA) warming is the most pronounced abrupt climate change event during the last deglaciation. Two notable features of the BA onset are found in our transient simulation of the last deglaciation with CCSM3: the first is the occurrence of an overshoot in the Atlantic Meridional Overturning Circulation (AMOC, about 20 Sv as to 13 Sv at Last Glacial Maximum) and the second is the subsequent transition of AMOC from a glacial (about 13 Sv) to an interglacial mean state (about 18 Sv). Here, we present two new sensitivity experiments to explicitly illustrate the impact of North Atlantic – GIN Sea exchange on the deglaciation evolution of the AMOC. In these sensitivity experiments, the oceanic exchange during the BA onset is inhibited by introducing a Partial Blocking scheme. In response to this, the deep-water formation in the GIN Sea is reduced by 80% compared to the transient simulation. This in turn results in a reduced AMOC overshoot followed by a lower mean state of the AMOC. Our results therefore suggest that, oceanic processes were more important than the external forcings and atmospheric processes for the AMOC evolution during the BA onset.
Crop yields response to water pressures in the Ebro basin in Spain: risk and water policy implications
Authors: Quiroga S. , Fernández-Haddad Z. , Iglesias A.
Published: February 2011

Abstract. The increasing pressure on water systems in the Mediterranean enhances existing water conflicts and threatens water supply for agriculture. In this context, one of the main priorities for agricultural research and public policy is the adaptation of crop yields to water pressures. This paper focuses on the evaluation of hydrological risk and water policy implications for food production. Our methodological approach includes four steps. For the first step, we estimate the impacts of rainfall and irrigation water on crop yields. However, this study is not limited to general crop production functions since it also considers the linkages between those economic and biophysical aspects which may have an important effect on crop productivity. We use statistical models of yield response to address how hydrological variables affect the yield of the main Mediterranean crops in the Ebro river basin. In the second step, this study takes into consideration the effects of those interactions and analyzes gross value added sensitivity to crop production changes. We then use Montecarlo simulations to characterize crop yield risk to water variability. Finally we evaluate some policy scenarios with irrigated area adjustments that could cope in a context of increased water scarcity. A substantial decrease in irrigated land, of up to 30% of total, results in only moderate losses of crop productivity. The response is crop and region specific and may serve to prioritise adaptation strategies.
Reliability and robustness of rainfall compound distribution model based on weather pattern sub-sampling
Authors: Garavaglia F. , Lang M. , Paquet E. , Gailhard J. , Garçon R. , Renard B.
Published: February 2011

Abstract. A new probabilistic model for daily rainfall, named MEWP (Multi Exponential Weather Pattern) distribution, has been introduced in Garavaglia et al. (2010). This model provides estimates of extreme rainfall quantiles using a mixture of exponential distributions. Each exponential distribution applies to a specific sub-sample of rainfall observations, corresponding to one of eight typical atmospheric circulation patterns that are relevant for France and the surrounding area. The aim of this paper is to validate the MEWP model by assessing its reliability and robustness with rainfall data from France, Spain and Switzerland. Data include 37 long series for the period 1904–2003, and a regional data set of 478 rain gauges for the period 1954–2005. Two complementary properties are investigated: (i) the reliability of estimates, i.e. the agreement between the estimated probabilities of exceedance and the actual exceedances observed on the dataset; (ii) the robustness of extreme quantiles and associated confidence intervals, assessed using various sub-samples of the long data series. New specific criteria are proposed to quantify reliability and robustness. The MEWP model is compared to standard models (seasonalised Generalised Extreme Value and Generalised Pareto distributions). In order to evaluate the suitability of the exponential model used for each weather pattern (WP), a general case of the MEWP distribution, using Generalized Pareto distributions for each WP, is also considered. Concerning the considered dataset, the exponential hypothesis of asymptotic behaviour of each seasonal and weather pattern rainfall records, appears to be reasonable. The results highlight : (i) the interest of WP sub-sampling that lead to significant improvement in reliability models performances; (ii) the low level of robustness of the models based on at-site estimation of shape parameter; (iii) the MEWP distribution proved to be robust and reliable, demonstrating the interest of the proposed approach.
Past terrestrial water storage (1980–2008) in the Amazon Basin reconstructed from GRACE and in situ river gauging data
Authors: Becker M. , Meyssignac B. , Xavier L. , Cazenave A. , Alkama R. , Decharme B.
Published: February 2011

Abstract. Terrestrial water storage (TWS) composed of surface waters, soil moisture, groundwater and snow where appropriate, is a key element of global and continental water cycle. Since 2002, the Gravity Recovery and Climate Experiment (GRACE) space gravimetry mission provides a new tool to measure large-scale TWS variations. However, for the past few decades, direct estimate of TWS variability is accessible from hydrological modeling only. Here we propose a novel approach that combines GRACE-based TWS spatial patterns with multi-decadal-long in situ river level records, to reconstruct past 2-D TWS over a river basin. Results are presented for the Amazon Basin for the period 1980–2008, focusing on the interannual time scale. Results are compared with past TWS estimated by the global hydrological model ISBA-TRIP. Correlations between reconstructed past interannual TWS variability and known climate forcing modes over the region (e.g., El Niño-Southern Oscillation and Pacific Decadal Oscillation) are also estimated. This method offers new perspective for improving our knowledge of past interannual TWS in world river basins where natural climate variability (as opposed to direct anthropogenic forcing) drives TWS variations.
Dissolved inorganic carbon export from carbonate and silicate catchments estimated from carbonate chemistry and δ13CDIC
Authors: Shin W. J. , Chung G. S. , Lee D. , Lee K. S.
Published: February 2011

Abstract. We investigated dissolved inorganic carbon (DIC) exchange associated with groundwater discharge and stream flow from two upstream catchments with distinct basement lithology (silicate vs. carbonate). The effects of catchment lithology were evident in the spring waters showing lower δ13CDIC and alkalinity (−16.2 ± 2.7‰ and 0.09 ± 0.03 meq L−1, respectively) in the silicate and higher values (−9.7 ± 1.5‰ and 2.0 ± 0.2 meq L−1) in the carbonate catchment. The streams exhibited relatively high δ13CDIC values, −6.9 ± 1.6‰ and −7.8 ± 1.5‰, in silicate and carbonate catchments, respectively, indicating CO2 degassing during groundwater discharge and stream flow. The catchment lithology affected the pattern of DIC export. The CO2 degassing from stream and groundwater could be responsible for 8–55% of the total DIC export in the silicate catchment, whereas the proportion is comparatively low (0.4–5.6%) in the carbonate catchment. We emphasize the importance of dynamic carbon exchange occurring at headwater regions and its variability with catchment lithology for a more reliable carbon budget in river systems.