bluuebunny/crossref_metadata_2025 huggingface dataset:
Greenhouse Gas Balance for Composting Operations
Authors: Brown Sally , Kruger Chad , Subler Scott
Published: June 2008

The greenhouse gas (GHG) impact of composting a range of potential feedstocks was evaluated through a review of the existing literature with a focus on methane (CH4) avoidance by composting and GHG emissions during composting. The primary carbon credits associated with composting are through CH4avoidance when feedstocks are composted instead of landfilled (municipal solid waste and biosolids) or lagooned (animal manures). Methane generation potential is given based on total volatile solids, expected volatile solids destruction, and CH4generation from lab and field incubations. For example, a facility that composts an equal mixture of manure, newsprint, and food waste could conserve the equivalent of 3.1 Mg CO2per 1 dry Mg of feedstocks composted if feedstocks were diverted from anaerobic storage lagoons and landfills with no gas collection mechanisms. The composting process is a source of GHG emissions from the use of electricity and fossil fuels and through GHG emissions during composting. Greenhouse gas emissions during composting are highest for high‐nitrogen materials with high moisture contents. These debits are minimal in comparison to avoidance credits and can be further minimized through the use of higher carbon:nitrogen feedstock mixtures and lower‐moisture‐content mixtures. Compost end use has the potential to generate carbon credits through avoidance and sequestration of carbon; however, these are highly project specific and need to be quantified on an individual project basis.
Treatment of Drainage Water with Industrial By‐Products to Prevent Phosphorus Loss from Tile‐Drained Land
Authors: McDowell R. W. , Sharpley A. N. , Bourke W.
Published: June 2008

Tile drained land with phosphorus (P)‐rich topsoil is prone to P loss, which can impair surface water quality via eutrophication. We used by‐products from steel and energy industries to mitigate P loss from tile drains. For each by‐product, P sorption maximum (Pmax) and strength (k) were determined, while a fluvarium trial assessed P uptake with flow rate. Although two ash materials (fly ash and bottom ash) had high Pmax and k values, heavy metal concentrations negated their use in the field. The fluvarium experiment determined that P uptake with by‐products was best at low flow, but decreased at higher flow in proportion to k. A mixture of melter slag (<10 mm) and basic slag (high Pmax, 7250 mg kg−1; and k, 0.508 L mg P−1) was installed as backfill in eight drains on a dairy farm. Four drains with greywacke as backfill were constructed for controls. The site (10 ha) had P‐rich topsoil (Olsen P of 64 mg kg−1) and yielded a mean dissolved reactive P (DRP) and total P (TP) concentration from greywacke backfilled drains of 0.33 and 1.20 mg L−1, respectively. In contrast, slag backfilled drains had DRP and TP concentrations of 0.09 and 0.36 mg L−1, respectively. Loads of DRP and TP in greywacke drains (0.45 and 1.92, respectively) were significantly greater (P < 0.05) than those from slag drains (0.18 and 0.85, respectively). Data from a farm where melter slag was used as a backfill suggested that slag would have a life expectancy of about 25 yr. Thus, backfilling tile drains with melter slag and a small proportion of basic slag is recommended as an effective means of decreasing P loss from high P soils.
Atrazine and Alachlor Transport in Claypan Soils as Influenced by Differential Antecedent Soil Water Content
Authors: Kazemi H. V. , Anderson S. H. , Goyne K. W. , Gantzer C. J.
Published: June 2008

Increased attention to ground water contamination has encouraged an interest in mechanisms of solute transport through soils. Few studies have investigated the effect of the initial soil water content on the transport and degradation of herbicides for claypan soils. We investigated the effect of claypan soils at initial field capacity vs. permanent wilting level on atrazine and alachlor transport. The soil studied was Mexico silt loam (fine, smectitic, mesic Aeric Vertic Epiaqualf) with a subsoil clay content, primarily montmorillonite, of >40%. Strontium bromide, atrazine, and alachlor were applied to plots; half were at field capacity (Wet treatment), and half were near the permanent wilting point (Dry treatment). Soil cores were removed at selected depths and times, and cores were analyzed for bromide and herbicide concentrations. Bromide, atrazine, and alachlor were detected at the 0.90‐m depth in dry plots within 15 d after experiment initiation. Bromide was detected 0.15 m deeper (P< 0.05) in the Dry compared with the Wet treatment at 1, 7, and 60 d after application and >0.30 m deeper (P< 0.01) in the Dry treatment at 15 and 30 d after application; similar treatment results were found for atrazine and alachlor, although on fewer dates with significant differences. The mobility order of the applied chemicals was bromide > atrazine > alachlor. The atrazine apparent half‐life was significantly longer in the Dry plots compared with the Wet plots. The retardation factor determined from the relative velocity of each herbicide to that of bromide was higher for alachlor than for atrazine. This study identifies the impact that shrinkage cracks have for different moisture conditions on preferential transport of herbicides in claypan soils.
VERMICOMPOSTING TECHNOLOGY FOR STABILIZING THE SEWAGE SLUDGE FROM RURAL WASTE WATER TREATMENT PLANTS
Authors: Cardoso V. Lina , Ramírez C. Esperanza , Escalante E. Violeta
Published: June 2008

There are problems associated with sludge management in small treatment plants (<10 L/s) located in rural communities, due to costly conventional technology for sludge stabilization. Many of these plants have only sludge drying beds. Mexican Institute of Water Technology has proposed developing suitable low-cost technologies, one of which is vermicomposting a biodegradation system using earthworms of the species Eisenia foetida (earthworm) which stabilize sludge and reduce its pathogenicity. The objective of this work is to present two case studies where vermicomposting technology has been applied in Mexico. The first study corresponds to a plant where 4.8 m3/month of sludge are produced; for these wastes, a vermicomposting system was built and installed. The second study is a treatment plant where 9 m3/month of sludge are produced; experimental tests were conducted with sludge and water hyacinth and a vermicomposting system was designed. The vermicomposts were analyzed using parameters defined by Mexican standards. In regards to stabilization, TVS was reduced by 38% and the microbiological quality of the vermicompost was Class A and B, with a reduction in fecal coliforms and Helminth eggs according to NOM-004-SEMARNAT-2002. A CRETI (Corrosivity, Reactivity, Explosivity, Toxicity and Ignitability) analysis (NOM-052-SEMARNAT-2005) was used to show that the process reduced the concentration of releasable sulfides. The agronomic quality of the vermicompost exhibited a high content of organic matter comparable to many organic manures and high content of nutrients such as nitrogen and phosphorus. It is concluded that it is possible to improve the conditions of sewage sludge management in small plants of rural communities with a minimum investment (less than $10,000.00 USD) and with a requirement of a minimum area of 60 to 70 m2 for a production of less than 9 m3/month of dehydrated sludge (80% humidity).
Compost from sewage sludge – a product with quality assurance system
Authors: Kranert Martin , Hafner Gerold , Berkner Ingrid , Erdin Ertugrul
Published: June 2008

While composting of separate collected bio-waste is currently undergoing a renaissance in Germany, sewage sludge composting offers as well the possibility to produce a hygienic soil conditioner and/or secondary raw material fertilizer. This alternative is increasingly interesting, especially to bring back nutrients and organic substances into soils. This paper explains the essential reasons for composting, shows the process conditions and the different composting processes used currently in Germany. The discussion about the heavy metal problem and the production of a high quality fair marketable product leads to the necessity of a quality assurance system, which has been proven to be effective for bio-waste composting in Germany. The necessary boundary conditions and demands for such a quality assurance system for sewage sludge are presented.
Production of fuels on the basis of sewage sludge through conditioning using high calorific value fractions
Authors: Schmelz Karl-Georg , Reipa Anja , Meyer Hartmut
Published: June 2008

Emschergenossenschaft and Lippeverband operate 59 wastewater treatment plants which produce approx. 100,000 Mg TS of sewage sludge each year. Using sludge pressure pipelines, about 60 % of this sludge are transported to the central sludge treatment plant in Bottrop. The digested sludges are conditioned using fine coal and polymers and are dewatered using membrane filters. By adding coal, the heating value of the sludge is raised which enables autothermal combustion of the dewatered sludges in fluidised bed furnaces at the central sludge treatment plant. In order to replace coal, a fossil fuel, as conditioning agent, experiments were conducted using alternative materials with high heating values. The addition of shredder fluff agglomerates proved to be particularly successful. Shredder fluff agglomerates are a residue from the recycling of used cars and are generated in a multistage process (e.g. Volkswagen-SiCon Process) by separating the light shredder fraction (plastic components etc.) from the total shredder fluff. The fibrous material is outstandingly suitable for improving the dewaterability and for sufficiently raising the heating value of the dewatered sludge in order to enable autothermal combustion. Since first experiments showed very positive results, a full-scale long-term test-run will take place in 2007.
Risks of pollution in water resources: PFC in the Möhne reservoir – what about public opinion?
Authors: Klein Peter
Published: June 2008

Sewage sludge polluted with high concentrations of PFC (perfluorated organic compounds) was spread as fertiliser on a cornfield in Brilon, Germany. During rainfall PFC are flushed out of the soil and flow into the Möhne and Ruhr River, where drinking water is extracted. PFC in elevated concentrations has been detected in the drinking water in this area. PFCs, used as industrial coating materials, are found ubiquitously, and in high concentrations are believed to be carcinogenic. The drinking-water problem has been mitigated by decontamination of the primary polluted field, a systematic and specific reservoir operation, and more extensive purification of drinking water.

In this region persons predominantly concerned are the population being supplied with drinking-water and some parts of the tourism industry in the Möhne reservoir area.

People in this area ask for a drinking water that is free from dangerous trace elements and residues of pharmaceuticals. Water management actors are called upon to realise consumers' wishes, to implement what is economically and technically possible and to show consumers the possibilities and the limits of drinking-water supply.
PUBLIC ACCEPTANCE OF SEWER FAILURES AND REHABILITATION WORKS: A CASE-STUDY FROM FRANCE AND PORTUGAL1
Authors: Barbier R. , Sousa D. , Montginoul M.
Published: June 2008

European cities face problems of sewerage and storm water systems wearing out, due to a combination of ageing infrastructure and increased urbanization. Its rehabilitation urges. This paper deals with disturbances on individuals' quality of life due to failures or rehabilitation works. It presents the results of a case-study which comprehends two target-areas: Nantes metropolis in France, and two municipalities of Lisbon metropolis in Portugal. On both areas a questionnaire was applied to a sample of target-populations.

This research results indicate that sewer failures and rehabilitation works are events that induce on disturbances especially in what concerns to the areas of housing and nearby surroundings. Nevertheless, being distinct type of situations, disturbances are lived in different ways as well as differently tolerated. This study also showed that those critical events may provoke, under certain circumstances, trust erosion of costumers towards sewerage utility. The last section aims at providing guidelines that could help local operators to set up a “consumer policy” especially in what concerns to sewer failures and rehabilitation works.
Risks and keeping customers' confidence: the key role of consumers' perception regarding the safety of tap water
Authors: van de Veerdonk Caroline , Van Essen Jan , Dekker Jos
Published: June 2008

Safe drinking water is a primary necessity to life that is of essential importance to public health. The water companies make sure that the water that comes out of the tap is safe to drink. The water companies are well aware of any actual risks in the process from source to tap, and they take many actions to avoid risks or to reduce the risks to an acceptable level. This is also what they communicate to their customers. But whether their customers are convinced that their drinking water is safe is decided not just by their knowledge of any actual risks, but also by their perception of such risks. To keep customer confidence high, it is of vital importance that the drinking water sector is aware of the consumers' perception regarding the safety of tap water: a risk may be negligible based on the facts, but might still become a big problem because of people's perception. Risk management thus should keep the balance between facts and perception.
Towards an improved human exposure assessment for contaminants in drinking water released by products used for domestic water distribution
Authors: Hoekstra Eddo J.
Published: June 2008

Substances migrated from products or micro-organisms released from biofilms in the domestic distribution system may affect the quality of tap water. The approach to protect consumers against these possible contaminants and specifically the sampling protocol for compliance monitoring at the tap is not well described in the European Drinking Water Directive. Regulators of the member states like to have guidance. This paper describes the issue and proposes a possible approach.
PIREM – PIPE REHABILITATION MANAGEMENT DEVELOPING A DECISION SUPPORT SYSTEM FOR REHABILITATION PLANNING OF WATER MAINS
Authors: Fuchs-Hanusch Daniela , Gangl Gerald , Kornberger Birgit , Kölbl Jörg , Hofrichter Johannes , Kainz Harald
Published: June 2008

The key aspect of the Pipe Rehabilitation Management (PiReM) research project is to develop a decision support system for the planning process of rehabilitation measures in water supply systems. The project is part of the “Waterpool” competence network which has the aim of supporting water works in the development of their competence with water. Therefore, research projects in cooperation between water works and research institutes have been generated. The result, in our case PiReM-software, ultimately belongs to the water works, and is to be used for their own planning or for consulting other water works. Currently, PiReM software supports the decision-making process of rehabilitation planning with two modules. These are long term rehabilitation strategies (10 years) and midterm rehabilitation planning (analysing rehabilitation priorities). The planning of annual construction sites is foreseen to be implemented as a third module.
WATER SUPPLIES FOR AUCKLAND - PREDICT AND PROVIDE OR CONSERVE AND CONTAIN?
Authors: Taylor Simon , Hodges James
Published: June 2008

Potable water services are provided to the population of 1.2m residents in the Auckland region of New Zealand by one wholesaler and six retailers. Forecasts for water demand suggest that a major new resource will be required by 2025 but that resource has not been identified at this time. Water efficiency techniques could defer this major capital investment. The paper discusses the region's water industry and the strategic investigations into water efficient alternatives to date.
Process evaluation of HASP with IMET system through SNR and SDNR for the efficient management of Sewage Treatment Plant
Authors: Yoon Young H. , Park Jae R. , Ahn Sang W. , Ko Kwang B. , Min Kyung J. , Gee Jae S.
Published: June 2008

Hybrid Activated Sludge Process (HASP) with IMET was developed and applied to an activated sludge process for the advanced nutrient treatment in Korea. The characteristics of nitrogen removal from the HASP were investigated through a kinetic study by batch-type experiment. Online DB analysis produced from the IMET was conducted for the nutrient removal performance in the field demonstration plant treating 10,000 m3/day in G city of Korea. In this paper, we aimed to determine the effect of increasing NHM4+-N load on the specific nitrification rate (SNR) and the specific denitrification rate (SDNR) through a batch-type experiment, and to estimate the net reaction time for the phase-transfer rate using online DB analysis in the HASP operation. Experimental results include: (1) both the nitrification and denitrification followed first-order kinetics; (2) the maximum SNR and SDNR were 4.0301 mgN/gVSS·hr and 2.785 mgN/gVSS·hr, respectively; (3) comparison of reaction rates between nitrification and denitrification from the non-linear regression analysis found that nitrification rate was higher than denitrification.
“We Talk of AIDS Because We Love Life”: A Stakeholder Assessment of HIV/AIDS Organizations in Buenos Aires, Argentina
Authors: Spaulding Alicen B. , Brieger William R.
Published: June 2008

This stakeholder assessment of HIV/AIDS service providing institutions in Argentina offers insights into the HIV/AIDS crisis in Spanish-speaking Latin America from an institutional level and makes recommendations for strengthening the work and functioning of these institutions. This stakeholder assessment was conducted to determine how HIV/AIDS prevention and management in Argentina affects and is affected by relevant HIV/AIDS institutions. Semi-structured qualitative interviews were conducted with 13 key leaders of organizations working in HIV/AIDS prevention in Buenos Aires including non-governmental, governmental, and academic institutions. Analyses of interviewee comments are presented according to four major themes: network connections, program resources, perceptions of success, and challenges. Key findings include the need for strengthening formal networks, increasing the involvement of other non-AIDS related social institutions in promoting HIV prevention, finding more sustainable funding options, working more effectively with the public sector to create policies and regulations favorable to the HIV/AIDS field, and addressing the lack of perceived susceptibility to HIV/AIDS in Argentine culture. From leaders' comments, recommendations are made for strengthening the HIV/AIDS network among key institutions including adapting the UNAIDS “Three Ones” principal to create one cross-sector office responsible for coordinating HIV/AIDS work, formalizing agreements with institutions outside of Buenos Aires, increasing the role of schools in HIV/AIDS awareness, and designing programs that address lack of perceived susceptibility to HIV/AIDS among Argentines.
Using “Mother Trainers” for Malaria Control: The Nigerian Experience
Authors: Ajayi Ikeoluwapo O. , Kale Oladele O. , Oladepo Oladimeji , Bamgboye E. Afolabi
Published: June 2008

Studies of care seeking in Nigeria show that a tremendous amount of treatment for malaria takes place at home and, in most instances, such treatments are incorrect. This deficiency is attributed to caregivers' poor knowledge of treatment. This study was designed to empower households to treat malaria correctly in partnership with community members. Selected mothers from study communities were trained as “mother trainers” and were expected to train other members of their communities using a treatment protocol. “Mother trainers” were acceptable to most communities and judged to be effective. They were enthusiastic and their participation in the study boosted their ego and status in the community. Drop-out-rate of “mother trainers” was 24.2%. A few limitations to the use of mothers as trainers that were identified are discussed. It is concluded that mothers have good potential to effectively carry out health education activities in the community if appropriately selected, trained, and supervised.
Microleakage of All-ceramic Crowns Using Self-etching Resin Luting Agents
Authors: Trajtenberg C. P. , Caram S. J. , Kiat-amnuay S.
Published: June 2008

Clinical Relevance

Among the self-adhesive resin cements, Panavia F 2.0 demonstrated less microleakage than RelyX Unicem or Multilink, whether or not a die spacer technique was used.
Depth of Cure of Dental Resin Composites: ISO 4049 Depth and Microhardness of Types of Materials and Shades
Authors: Moore B. K. , Platt J. A. , Borges G. , Chu T-M. G. , Katsilieri I.
Published: June 2008

Clinical Relevance

Achieving a high degree of cure throughout a 2 mm thickness of light-activated resin composite did not occur for many types and shades of resin composite. Clinicians should check the depth of cure by using the scraping method.
Color Stability of Nanocomposites Polished with One-Step Systems
Authors: Ergücü Z. , Türkün L. S. , Aladag A.
Published: June 2008

Clinical Relevance

The color stability of nanocomposites depends on the material's properties, rather than the polishing systems used.
Effect of Prior Acid Etching on Bonding Durability of Single-Step Adhesives
Authors: Watanabe T. , Tsubota K. , Takamizawa T. , Kurokawa H. , Rikuta A. , Ando S. , Miyazaki M.
Published: June 2008

Clinical Relevance

The ability of acid etching to increase enamel bond strengths varies among single-step self-etch adhesive systems.
Effect of Restorative Technique and Thermal/Mechanical Treatment on Marginal Adaptation and Compressive Strength of Esthetic Restorations
Authors: Paula A. B. , Duque C. , Correr-Sobrinho L. , Puppin-Rontani R. M.
Published: June 2008

Clinical Relevance

This study demonstrated that esthetic restorations prepared with indirect or direct techniques had similar compressive strengths and marginal adaptation. Marginal deterioration over time was observed for both types of restorations; however, there was an increase in the prevalence of catastrophic fractures among direct restorations.
Reversal of Compromised Bonding in Bleached Enamel Using Antioxidant Gel
Authors: Kaya A. D. , Türkün M. , Arici M.
Published: June 2008

Clinical Relevance

Dental bond strength is significantly reduced when bonding is performed immediately after bleaching treatments. It has also been reported that the application of an antioxidant after bleaching treatment improves the adhesive bond strength of oxidized enamel tissue. The application of an antioxidant in gel form by the patient makes the application process easier and shortens time spent in the clinic.
Amalgam Safety and Dentists' Attitude: A Survey Among a Subpopulation of Nigerian Dentists
Authors: Udoye C. , Aguwa E.
Published: June 2008

Clinical Relevance

This manuscript presents a cross-sectional survey report on amalgam use, attitudes and perception by dentists in Nigeria, a developing nation, on a subject of clinical relevance to all dentists.
Clinical Evaluation of an All-in-one Adhesive in Non-Carious Cervical Lesions with Different Degrees of Dentin Sclerosis
Authors: Ritter A. V. , Heymann H. O. , Swift E. J. , Sturdevant J. R. , Wilder A. D.
Published: June 2008

Clinical Relevance

Lower scores for marginal discoloration and adaptation were noted when an all-in-one self-etching adhesive was applied to non-carious cervical lesions and compared to a three-step total-etch adhesive.
Comparison of Traditional and Low Sensitivity Whiteners
Authors: Browning W. D. , Chan D. C. , Myers M. L. , Brackett W. W. , Brackett M. G. , Pashley D. H.
Published: June 2008

Clinical Relevance

The results of this double-blind, placebo-controlled clinical trial have direct relevance to clinical practice and provide evidence that the addition of low levels of potassium nitrate and/or potassium nitrate and fluoride significantly reduce postoperative sensitivity relative to products that do not contain either agent.
On Possible Determination of the Speed of the Gravity Signal in Space with help of Gradiometry
Authors: Zieliński Janusz , Gałązka Robert , Peron Roberto
Published: June 2008

On Possible Determination of the Speed of the Gravity Signal in Space with help of Gradiometry
Transfer of HRM Practices to Subsidiaries: Importance of the Efficiency of the HRM System
Authors: Lertxundi Aitziber
Published: June 2008

This work shows the importance of evaluating the efficiency of the human resource management system in the analysis of transfer/adaptation costs of human resources practices in multinational enterprises. In addition to the cost factors that have traditionally been considered, system cost and opportunity cost are examined. Concretely, I propose to estimate the latter in accordance with the quality of the human resources function and conclude that the optimum strategic option would depend on the effectiveness of the system as a source of competitive advantage.
Recent glacier variations at the Aconcagua basin, central Chilean Andes
Authors: Bown Francisca , Rivera Andrés , Acuña César
Published: June 2008

The majority of glaciers in central Chile have receded in recent decades, from >50m to only a few meters per year, mainly in response to an increase in the 0˚C isotherm altitude. The Aconcagua river basin (33˚ S) is one of the major glaciated basins in central Chile, with 121 km2 of ice in 2003. An earlier inventory using 1955 aerial photographs yielded a total surface area of 151 km2, implying a reduction in glacier area of 20% (0.63km2 a–1) over the 48 years. Photographic stereo models, high-resolution satellite images (Landsat, ASTER) and SRTM data have been used to delineate glacier basins. A focus on Glaciar Juncal Norte, one of the largest glaciers in the basin, allows a more detailed analysis of changes. The glacier has exhibited a smaller reduction (14%) between 1955 and 2006, and the resulting elevation changes over this smaller period are not significant. The above reduction rates are lower than in other glaciers of central Chile and Argentina. This trend emphasizes water runoff availability in a river where most of the water in the dry summers is generated by glaciers and snowpack, and where most of the superficial water rights are already allocated. Ongoing hydrological research including modelling of future water runoff will improve our understanding.
A change in seasonality in Greenland during a Dansgaard–Oeschger warming
Authors: Thomas Elizabeth R. , Mulvaney Robert , Wolff Eric W.
Published: June 2008

A new sub-seasonal chemical record is presented from the North Greenland Icecore Project (NorthGRIP) ice core during the onset of one of the longest and strongest interstadials of the last glacial period, Dansgaard–Oeschger event 8 (approximately 38 000 years ago). This is the first time that a record of such resolution has been achieved over several metres of deep glacial ice and provides a unique opportunity for using additional parameters to carry out accurate dating using annual-layer counting. The very high-resolution chemical data were used to assess the phasing of various ions and determine changes in the seasonal strength of chemical deposition and the shape of the seasonal cycle. The study shows that a change in seasonality accompanied the dramatic warming transition from stadial to interstadial conditions in Greenland.
Climate sensitivity and mass-balance evolution of Gran Campo Nevado ice cap, southwest Patagonia
Authors: Möller Marco , Schneider Christoph
Published: June 2008

A degree-day model extended for surface mass-balance calculations has been applied to derive the sensitivity of Gran Campo Nevado ice cap (GCN), southwest Patagonia, to climate change. Seasonal sensitivity characteristics were computed using automatic weather station data gathered in the period 2000–05. Results indicate pronounced mass-balance sensitivity to temperature during the summer, with monthly values of –0.27±0.01mw.e. K–1. Monthly sensitivity to a 10% precipitation perturbation fluctuates around +0.03mw.e The sensitivity characteristics obtained were used to model the surface mass-balance evolution of GCN during the 20th and 21 st centuries based on monthly means of air temperature and precipitation derived from bias-corrected weather station data and statistically downscaled re-analysis and general climate model data. Surface mass balance shows a persistently negative trend ranging from around +1mw.e. a–1 at the beginning of the 20th century down to almost –1.5mw.e. a–1 during the first years of the 21st century, with only a few positive years occurring occasionally during the second half of the 20th century. The scenario for the end of the 21 st century totals approximately –4.5mw.e. a–1, i.e. an estimated ice volume loss for GCN of 59 km3 during 1900–2099.
Modelling binge–purge oscillations of the Laurentide ice sheet using a plastic ice sheet
Authors: Steen-Larsen H.C. , Dahl-Jensen D.
Published: June 2008

A simple combined heat and ice-sheet model has been used to calculate temperatures at the base of the Laurentide ice sheet. We let the ice sheet surge when the basal temperature reaches the pressure-melting temperature. Driving the system with the observed accumulation and temperature records from the GRIP ice core, Greenland, produces surges corresponding to the observed Heinrich events. This suggests that the mechanism of basal sliding, initiated when the basal temperature reaches the melting point, can explain the surges of the Laurentide ice sheet. This study highlights the importance of the surface temperature and accumulation rate as a means of forcing the timing and strength of the Heinrich events, thus implying important ice-sheet climate feedbacks.
The recent evolution of Liligo glacier, Karakoram, Pakistan,and its present quiescent phase
Authors: Belo Marco , Mayer Christoph , Smiraglia Claudio , Tamburini Andrea
Published: June 2008

Liligo glacier, in the central eastern Karakoram, Pakistan, is a small, south-to-north-flowing glacier situated in a transverse valley on the left (south) side of Baltoro glacier. New processing of satellite imagery enables a better quantification of terminus oscillations over the past 30 years. From the beginning of the 1970s to the beginning of the 21st century, Liligo glacier advanced about 2 km (60ma–1). The progress was characterized by a significant evolution of terminus morphology, similar to that observed on the same glacier during the advance event near the beginning of the 20th century, and to those of many other Karakoram glaciers. This suggests indications of a surge-type mechanism. Field observations performed in 2004 indicated there was probably no confluence at that time between Liligo and Baltoro glaciers and that a quiescent phase had started in the early years of the 21st century.
Extreme intra-seasonal anomalies in the Amundsen and Bellingshausen sea-ice area, Antarctica, during the austral winter
Authors: de Lima Fabio Ullmann Furtado , de Carvalho Leila M. Véspoli
Published: June 2008

We examine the role of the propagation of atmospheric mid-latitudes wave trains in modulating the Amundsen and Bellingshausen sea-ice area (SIA), Antarctica, on intra-seasonal timescales (20–100 days). Spectral analysis of passive microwave estimates of SIA in the Amundsen and Bellingshausen Seas for 1979–2004 shows significant peaks on intra-seasonal timescales. Previous studies have suggested that variations in SIA are linked to disturbances in atmospheric circulation and sea surface temperature. We show that extreme SIA anomalies on intra-seasonal timescales lag the propagation of subtropical wave trains in the Southern Hemisphere by approximately 10–15 days. The sign of the SIA anomaly depends on the phase of the wave. We present evidence that the number of disturbances that cause extreme anomalies of SIA on intra-seasonal timescales has increased in the last 14 years.
Spatial distribution of debris thickness and melting from remote-sensing and meteorological data, at debris-covered Baltoro glacier, Karakoram, Pakistan
Authors: Mihalcea C. , Mayer C. , Diolaiuti G. , D’Agata C. , Smiraglia C. , Lambrecht A. , Vuillermoz E. , Tartari G.
Published: June 2008

A distributed surface energy-balance study was performed to determine sub-debris ablation across a large part of Baltoro glacier, a wide debris-covered glacier in the Karakoram range, Pakistan. The study area is ~124km2. The study aimed primarily at analyzing the influence of debris thickness on the melt distribution. The spatial distribution of the physical and thermal characteristics of the debris was calculated from remote-sensing (ASTER image) and field data. Meteorological data from an automatic weather station at Urdukas (4022ma.s.l.), located adjacent to Baltoro glacier on a lateral moraine, were used to calculate the spatial distribution of energy available for melting during the period 1–15 July 2004. The model performance was evaluated by comparisons with field measurements for the same period. The model is reliable in predicting ablation over wide debris-covered areas. It underestimates melt rates over highly crevassed areas and water ponds with a high variability of the debris thickness distribution in the vicinity, and over areas with very low debris thickness (<0.03 m). We also examined the spatial distribution of the energy-balance components (global radiation and surface temperature) over the study area. The results allow us to quantify, for the study period, a meltwater production of 0.058 km3.
Arctic sea-ice variability revisited
Authors: Stroeve Julienne , Frei Allan , McCreight James , Ghatak Debjani
Published: June 2008

This paper explores spatial and temporal relationships between variations in Arctic sea-ice concentration (summer and winter) and near-surface atmospheric temperature and atmospheric pressure using multivariate statistical techniques. Trend, empirical orthogonal function (EOF) and singular value decomposition (SVD) analyses are used to identify spatial patterns associated with covariances and correlations between these fields. Results show that (1) in winter, the Arctic Oscillation still explains most of the variability in sea-ice concentration from 1979 to 2006; and (2) in summer, a decreasing sea-ice trend centered in the Pacific sector of the Arctic basin is clearly correlated to an Arctic-wide air temperature warming trend. These results demonstrate the applicability of multivariate methods, and in particular SVD analysis, which has not been used in earlier studies for assessment of changes in the Arctic sea-ice cover. Results are consistent with the interpretation that a warming signal has now emerged from the noise in the Arctic sea-ice record during summer. Our analysis indicates that such a signal may also be forthcoming during winter.
Sediment–moss interactions on a temperate glacier: Falljökull, Iceland
Authors: Porter P.R. , Evans A.J. , Hodson A.J. , Lowe A.T. , Crabtree M.D.
Published: June 2008

We present the results of preliminary investigations of globular moss growth on the surface of Falljökull, a temperate outlet glacier of the Vatnajökull ice cap, southern Iceland. Supraglacial debris has provided a basis for moss colonization, and several large (>500m2) patches of moss growth (Racomitrium spp.) are observed on the surface of the glacier. Each area of moss-colonized supraglacial debris shows a downslope increase in sphericity and moss cushion size and a decrease in percentage surface coverage of moss-colonized and bare clasts. It is suggested that moss growth on supraglacial debris allows preferential downslope movement of clasts through an associated increase in both overall mass and sphericity. Thermal insulation by moss cushions protects the underlying ice surface from melt, and the resulting ice pedestals assist in downslope sliding and toppling of moss cushions. The morphology and life cycle of supraglacial globular mosses is therefore not only closely linked to the presence and distribution of supraglacial debris, but also appears to assist in limited down-glacier transport of this debris. This research highlights both the dynamic nature of the interaction of mosses with supraglacial sedimentary systems and the need for a detailed consideration of their role within the wider glacial ecosystem.
Comparison of sea-ice extent and ice-edge location estimates from passive microwave and enhanced-resolution scatterometer data
Authors: Meier Walter N. , Stroeve Julienne
Published: June 2008

Passive microwave sea-ice concentration fields provide some of the longest-running and most consistent records of changes in sea ice. Scatterometry-based sea-ice fields are more recently developed data products, but now they provide a record of ice conditions spanning several years. Resolution enhancement techniques applied to scatterometer fields provide much higher effective resolutions (~10 km) than are available from standard scatterometer and passive microwave fields (25–50 km). Here we examine ice-extent fields from both sources and find that there is general agreement between scatterometer data and passive microwave fields, though scatterometer estimates yield substantially lower ice extents during winter. Comparisons with ice-edge locations estimated from AVHRR imagery indicate that enhanced scatterometer data can sometimes provide an improved edge location, but there is substantial variation in the results, depending on the local conditions. A blended product, using both scatterometer and passive microwave data, could yield improved results.
Assessment of techniques for analyzing snow crystals in two dimensions
Authors: Bartlett Stuart John , Rüedi Jean-Daniel , Craig Alasdair , Fierz Charles
Published: June 2008

Three-dimensional (3-D) snow analysis techniques provide comprehensive and accurate snow microstructure data. Nevertheless, there remains a requirement for less elaborate methods for snow characterization, as numerical snow models such as SNOWPACK are presently based on two-dimensional (2-D) grain analysis. We present a detailed assessment of various methods and shape descriptors used for snow characterization from digitized images. Dendricity, the ratio of the square of grain perimeter to its area, allows distinction between new and old snow while sphericity distinguishes between faceted and rounded grains. The concept of sphericity is based on curvature, yet another powerful shape descriptor. However, curvatures obtained from images of disaggregated snow grains depend on both resolution and methods chosen. We compared the standard parabola method with a cubic smoothing spline approach for curvature measurement. Applying both methods to parametrically generated shapes, descriptor values were compared with their analytical counterparts. The spline method was found to be able to measure a wider range of curvatures accurately, but both methods suffered from a filtering effect. Although some descriptor errors were as high as 50%, a method for effectively outlining snow grains was found. As well as assessing the classification potential of 2-D analysis on full samples, new descriptors were also investigated.
A bonding process between grains in mechanically disaggregated snow
Authors: Adams Edward E. , Jepsen Steven M. , Close Bryan
Published: June 2008

Collections of disaggregated snow particles were examined in a temperature-controlled microscope stage. In addition to necks that appeared to sinter in a manner congruent with the two-particle model, there also appeared unanticipated dendritic growth, which developed on some grains and grew into the pore space. These branches developed preferentially only on part of, and in different directions on, individual grains. Some of these grew enough to join with adjacent grains that were in close proximity but not initially in contact, while the surface of the adjacent grains did not show measurable growth or loss. Growth orientation is hypothesized to be due to crystal habit dependence on temperature. Columnar growth was observed at –5˚C and plate-like at –15˚C. The random growth orientation is in contrast to observed source and sink development aligned with a temperature gradient imposed using a gradient stage. In this case, a source-to-sink directionality across the pore was apparent in which faceted crystals grew at the expense of neighboring source grains. The process of mechanically disaggregating snow produces numerous broken shards and sharp-edged fracture surfaces. We hypothesize that it is the sublimation of these high-surface-energy regions that provides the excess vapor to facilitate the diffusion-limited dendritic growth observed in this ‘equitemperature’, mechanically processed snow.
Computational fluid dynamic (CFD) simulation of snowdrift in alpine environments, including a local weather model, for operational avalanche warning
Authors: Schneiderbauer Simon , Tschachler Thomas , Fischbacher Johann , Hinterberger Walter , Fischer Peter
Published: June 2008

A new continuum approach to snowdrift modelling is introduced. In addition, numerical studies are carried out to identify the influence of time-varying wind conditions on snowdrift simulations. We compare the snowdrift patterns at Grimming mountain, Austria, derived using a time-averaged wind field and a time-varying wind field obtained from the numerical weather prediction model INCA. The results show significant differences in the deposition patterns and snow depth even after a 6 hour drift period. Using time-averaged boundary conditions leads to an underprediction of the resulting snow depth caused by averaging the wind speed, which lets gusts of wind disappear while snow transport is a non-linear function of the wind speed. Using numerical weather prediction models for snowdrift simulation therefore provides enhanced knowledge of the snow depth for local avalanche warning services.
Influence of precipitation seasonality on glacier mass balance and its sensitivity to climate change
Authors: Fujita Koji
Published: June 2008

Numerical calculations are described, aimed at evaluating the influence of precipitation seasonality (summer and winter) on glacier mass balance. First, equilibrium-line altitudes (ELAs) are modeled using idealized meteorological variables. Modeled climatic conditions (summer mean temperature and annual precipitation) at the ELA of glaciers located within a winter accumulation pattern confirm the observational results of earlier studies. However, the ELA of glaciers located within a summer accumulation climate pattern locates in a colder environment than that of glaciers located within a winter accumulation climate pattern. This difference is mainly due to the annual snow accumulation and the surface albedo. A warming test (+1K) reveals higher sensitivities for the glaciers located within a summer accumulation pattern than for the glaciers located within a winter accumulation pattern. In a humid environment, a significant decrease in snow accumulation on the glaciers located within a summer accumulation pattern directly causes higher sensitivities. In an arid environment, on the other hand, the decreased summer snow induces accelerated melting by lowering the surface albedo and thus increasing absorption of solar radiation on the glaciers located within a summer accumulation pattern. Both influences are due to significant differences in summer precipitation. This study shows the importance of precipitation seasonality on the climatic sensitivity of glacier mass balance, which in previous studies has been linked only with annual precipitation.
Polymer Multilayer Microspheres Loaded with Semiconductor Quantum Dots
Authors: Petukhova Alla , Paton Andrew S. , Wei Zhixiang , Gourevich Ilya , Nair Selvakumar V. , Ruda Harry E. , Shik Alexander , Kumacheva Eugenia
Published: June 2008

Optically active nanostructures comprised of polymer multilayer microspheres surrounding semiconductor quantum dots are studied. Comparative analysis of the optical properties of the microspheres with four alternating layers with different refractive indices is performed. Photoluminescence and extinction characteristics of the microspheres are determined by the dimensions, internal structure, and the average refractive index of the particles.
Lattice‐Registered Two‐Photon Polymerized Features within Colloidal Photonic Crystals and Their Optical Properties
Authors: Nelson Erik C. , García‐Santamaría Florencio , Braun Paul V.
Published: June 2008

In this work we demonstrate a significant advance in the introduction of embedded defects in 3D photonic crystals by means of two‐photon polymerization. We have developed the ability to precisely position embedded defects with respect to the lattice of 3D photonic crystals by imaging the structure concurrently with two‐photon writing. Defects are written with near‐perfect lattice registration and at specifically defined depths within the crystal. The effect of precise defect position on the optical response is investigated for embedded planar cavities written in a photonic crystal. The experimental data are compared to spectra calculated using the Scalar Wave Approximation (SWA).
Efficient Nonlinear Absorbing Platinum(II) Acetylide Chromophores in Solid PMMA Matrices
Authors: Westlund Robert , Malmström Eva , Lopes Cesar , Öhgren Johan , Rodgers Thomas , Saito Yuika , Kawata Satoshi , Glimsdal Eirik , Lindgren Mikael
Published: June 2008

Platinum(II) acetylides were incorporated into poly(methyl methacrylate) (PMMA) glasses to obtain solid‐state nonlinear optical devices. We report on device fabrication, structural, chemical, and mechanical properties, as well as the optical limiting capabilities of the final solids. Two different guest‐host systems are presented: 1) Dye molecules functionalized to be readily dispersed in methyl methacrylate (MMA) and subsequent in situ polymerization of the MMA yielding solid PMMA host matrices. 2) Dye molecules functionalized to copolymerize with MMA forming covalent bonds between the guest and the PMMA host matrix. A range of doped organic solids were prepared, reaching concentrations up to 13 wt% of the guest molecule. Raman spectra of the doped solid devices indicate that the chemical structure of the nonlinear dyes remains intact upon the polymerization of the solid matrix. Luminescence spectra confirm that the basic photophysical properties observed for the same solute molecules in THF are maintained also in the solid state. Optical power limiting (OPL) characterization reveal clamping levels for the dyes nonbonded to the solid host being less than 4 µJ at pulse energies up to 110 µJ at 532 nm (f/5 arrangement and 5 ns pulses), which is comparable to the performance of similar dyes in THF solutions. In contrast, the highly crosslinked solid possesses a higher clamping level (8 µJ) at the same nominal concentration.
Fully Enzymatic Resolution of Chiral Amines: Acylation and Deacylation in the Presence of Candida antarctica Lipase B
Authors: Ismail Hilda , Lau Rute Madeira , van Rantwijk Fred , Sheldon Roger A.
Published: June 2008

A fully enzymatic methodology for the resolution of chiral amines has been demonstrated. Candida antarctica lipase B (CaLB)‐catalyzed acylation with N‐methyl‐ and N‐phenylglycine, as well as analogues having the general formula R1XCH2CO2R2 (R1=Me, Ph; X=O, S) afforded the corresponding enantioenriched amides, which were subsequently enzymatically hydrolyzed. Surprisingly, CaLB also proved to be the catalyst of choice for this latter step. The heteroatom in the acyl donor profoundly influences both the enzymatic acylation and deacylation; the O‐substituted reagents performed best with regard to enantioselectivity as well as reaction rate in synthesis and hydrolysis.