Influence of convective transport on tropospheric ozone and its precursors in a chemistry-climate model

The impact of convection on tropospheric O₃ and its precursors has been examined in a coupled chemistry-climate model. There are two ways that convection affects O₃. First, convection affects O₃ by vertical mixing of O₃ itself. Convection lifts lower tropospheric air to regions where the O₃ lifetime is longer, whilst mass-balance subsidence mixes O₃-rich upper tropospheric (UT) air downwards to regions where the O₃ lifetime is shorter. This tends to decrease UT O₃ and the overall tropospheric column of O₃. Secondly, convection affects O₃ by vertical mixing of O₃ precursors. This affects O₃ chemical production and destruction. Convection transports isoprene and its degradation products to the UT where they interact with lightning NO_x to produce PAN, at the expense of NO_x. In our model, we find that convection reduces UT NO_x through this mechanism; convective down-mixing also flattens our imposed profile of lightning emissions, further reducing UT NO_x. Over tropical land, which has large lightning NO_x emissions in the UT, we find convective lofting of NO_x from surface sources appears relatively unimportant. Despite UT NO_x decreases, UT O₃ production increases as a result of UT HO_x increases driven by isoprene oxidation chemistry. However, UT O₃ tends to decrease, as the effect of convective overturning of O₃ itself dominates over changes in O₃ chemistry. Convective transport also reduces UT O₃ in the mid-latitudes resulting in a 13% decrease in the global tropospheric O₃ burden. These results contrast with an earlier study that uses a model of similar chemical complexity. Differences in convection schemes as well as chemistry schemes – in particular isoprene-driven changes are the most likely causes of such discrepancies. Further modelling studies are needed to constrain this uncertainty range

Is query translation a distinct task from search?

INTRODUCTION The University of Sheffield participated in iCLEF 2002 using, as a test-bed, the prototype under development in the Clarity project. Clarity is an EU funded project aimed at developing a system for cross-language information retrieval for so-called low density languages, those with few translation resources. Currently translation between English and Finnish is supported; soon Swedish will be added and in the near future Latvian and Lithuanian. Clarity is being developed in a user-centred way with user involvement from the beginning. The design of the first user interface was based on current best practise, particular attention was paid to empirical evidence for a specific design choice. Six paper-based interface mock-ups representing important points in the cross-language search task were generated and presented for user assessment as a part of an extensive user study. The study (reported in Petrelli et al. 2002) was conducted to understand users and uses of cross-language information retrieval systems. Many different techniques were applied: contextual enquiry, interviews, questionnaires, informal evaluation of existing cross-language technology, and participatory design sessions with the interface mock-ups mentioned above. As a result, a user class profile was sketched and a long list of user requirements was compiled. As a followup, a redesign session took place and the new system was designed for users whoknow the language(s) they are searching (polyglots); • search for writing (journalists, translators business analysts); • have limited searching skills; • know the topic in advance or will learn/read on it while searching; • use many languages in the same search session and often swap between them. New system features were listed as important and the user interface was redesigned. Considering the result of the study the new interface allowed the user to dynamically change the language setting from query to query, hid the query translation and showed the retrieved set as ranked list primary. Despite the fact that this new design was considered to be more effective, a comparison between the first layout based on the relevant literature and the new one based on the user study was considered an important research question. In particular, the choice of hiding the query translation was considered an important design decision, against the common agreement to allow and support the user in controlling the system actions. Thus the participation of Sheffield in iCLEF was organized around the idea of checking if the user should validate the query translation before the search is run or instead if the system should perform the translation and search in a single step without any user’s supervision

Many-body interactions in a quantum wire in the integer quantum Hall regime: suppression of exchange-enhanced g factor

The collapse of Hall gaps in the integer quantum Hall liquid in a quantum wire is investigated. Motivated by recent experiment [Pallecchi et al. PRB 65, 125303 (2002)] previous approaches are extended to treat confinement effects and the exchanged enhanced g-factor in quantum wires. Two scenarios for the collapse of the $\nu =1$ state are discussed. In the first one the $\nu =1$ state becomes unstable at $B_{cr}^{(1)}$, due to the exchange interaction and correlation effects, coming from the edge-states screening. In the second scenario, a transition to the $\nu =2$ state occurs at $B_{cr}^{(2)}$, with a smaller effective channel width, caused by the redistribution of the charge density. This effect turns the Hartree interaction essential in calculating the total energy and changes $B_{cr}^{(2)}$ drastically. In both scenarios, the exchange enhanced g-factor is suppressed for magnetic fields lower than $B_{cr}$. Phase diagrams for the Hall gap collapse are determined. The critical fields, activation energy, and optical $g$-factor obtained are compared with experiments. Within the accuracy of the available data, the first scenario is most probable to be realized.Comment: 11 pages, 10 figure

Richness and Abundance of Carabidae and Staphylinidae (Coleoptera), in Northeastern Dairy Pastures Under Intensive Grazing

Dairy cattle has become popular to dairy farmers in the Northeast looking for management schemes to cut production costs. Carabidae (ground beetles) and Staphylinidae (rove beetles) are indicators of habitat disturbances, such as drainage of wetlands, or grassland for grazing animals, and their monitoring could provide one measure of ecosystem sustainability if intensive management systems expand or intensify in the future. Our objective was assess the abundance and species richness of these two beetle families under intensive grazing throughout Pennsylvania, southern New York and Vermont. We collected 4365 ground beetles (83 species) and 4,027 rove beetles (79 species) by pitfall traps in three years in Pennsylvania. Nine ground beetle species, Amara aenea, Poecilus chalcites, Pterostichus melanarius, Bembidion quadrimaculatum oppositum, Amara familiaris, Poecilus lucublandus, Agonum muelleri, Bembidion obtusum and Bembidion mimus represented 80% of the Carabidae collected. Five other species were new to Pennsylvania. Four rove beetle species, Philonthus cognatus, Meronera venustula, Amischa analis, and Philonthus various = (carbonarius), comprised 74% of the total Staphylinidae collected. Yearly distributions of the dominant species did not change significantly in the three years with A. aenea and P. cognatus being most abundant every year. A parasitic rove beetle, Aleochara tristis, was recovered for the first time in Pennsylvania and Vermont since its release in the 1960\u27s to control face fly, Musca autumnalis. Similar results were found in New York and Vermont. We collected 1,984 ground beetles (68 species). Pterostichus melanarius was most abundant. Pterostichus vernalis was detected for the first time in the United States (Vermont). It was previously reported from Montreal, Canada. We collected 843 rove beetles (45 species). Philonthus cognatus was the most abundant rove beetle. In addition, Tachinus corticinus, previously known only from Canada, was discovered for the first time in the United States in Vermont. Pastures in Pennsylvania were diverse, containing 14 species of forage plants and 17 weed species. Botanical composition was similar in New York and Vermont. Sixteen species of grasses and legumes made up 90% of the plant composition and 36 species of weeds made up the remainder. This di­verse plant ecosystem may explain the richness of ground and rove beetles in northeastern U.S. pastures because the heterogeneity in the plant population provided additional resources which can support a rich assemblage of beetles. Monitoring richness and abundance of Carabidae and Staphylinidae over three years in Pennsylvania suggests intensive grazing systems are eco­logically sustainable

Following basal stem rot in young oil palm plantings

The PCR primer GanET has previously been shown to be suitable for the specific amplification of DNA from Ganoderma boninense. A DNA extraction and PCR method has been developed that allows for the amplification of the G. boninense DNA from environmental samples of oil palm tissue. The GanET primer reaction was used in conjunction with a palm-sampling programme to investigate the possible infection of young palms through cut frond base surfaces. Ganoderma DNA was detected in frond base material at a greater frequency than would be expected by comparison with current infection levels. Comparisons are made between the height of the frond base infected, the number of frond bases infected, and subsequent development of basal stem rot. The preliminary results suggest that the development of basal stem rot may be more likely to occur when young lower frond bases are infected

Reading between the lines: attitudinal expressions in text

This is a brief overview of the starting points a project currently proposed and under evaluation by funding agencies. We discuss some of the linguistic methodology we plan to employ to idenitify and analyze attitudinal expressions in text, and touch briefly on how to evaluate our future results

UK utility data integration: overcoming schematic heterogeneity

In this paper we discuss syntactic, semantic and schematic issues which inhibit the integration of utility data in the UK. We then focus on the techniques employed within the VISTA project to overcome schematic heterogeneity. A Global Schema based architecture is employed. Although automated approaches to Global Schema definition were attempted the heterogeneities of the sector were too great. A manual approach to Global Schema definition was employed. The techniques used to define and subsequently map source utility data models to this schema are discussed in detail. In order to ensure a coherent integrated model, sub and cross domain validation issues are then highlighted. Finally the proposed framework and data flow for schematic integration is introduced

An evaluation resource for geographic information retrieval

In this paper we present an evaluation resource for geographic information retrieval developed within the Cross Language Evaluation Forum (CLEF). The GeoCLEF track is dedicated to the evaluation of geographic information retrieval systems. The resource encompasses more than 600,000 documents, 75 topics so far, and more than 100,000 relevance judgments for these topics. Geographic information retrieval requires an evaluation resource which represents realistic information needs and which is geographically challenging. Some experimental results and analysis are reported

GeoCLEF 2007: the CLEF 2007 cross-language geographic information retrieval track overview

GeoCLEF ran as a regular track for the second time within the Cross Language Evaluation Forum (CLEF) 2007. The purpose of GeoCLEF is to test and evaluate cross-language geographic information retrieval (GIR): retrieval for topics with a geographic specification. GeoCLEF 2007 consisted of two sub tasks. A search task ran for the third time and a query classification task was organized for the first. For the GeoCLEF 2007 search task, twenty-five search topics were defined by the organizing groups for searching English, German, Portuguese and Spanish document collections. All topics were translated into English, Indonesian, Portuguese, Spanish and German. Several topics in 2007 were geographically challenging. Thirteen groups submitted 108 runs. The groups used a variety of approaches. For the classification task, a query log from a search engine was provided and the groups needed to identify the queries with a geographic scope and the geographic components within the local queries