bluuebunny/crossref_metadata_2025 huggingface dataset:
Judgment and action knowledge in speed adjustment tasks: experiments in a virtual environment
Authors: Huber Susanne , Krist Horst , Wilkening Friedrich
Published: December 2004

Two experiments were conducted to investigate children's and adults’ knowledge of time and speed in action and judgment tasks. Participants had to set the speed of a moving car to a new speed so that it would reach a target line at the same time as a reference car moving at a higher speed and disappearing in a tunnel at the midway point. In Experiment 1 (24 10‐year‐olds, 24 adults), children's and adults’ speed adjustments followed the normative pattern when responses had to be graded linearly as a function of the car's initial speed. In a non‐linear condition, only adults’ action responses corresponded with the normative function. Simplifying the task by shortening the tunnel systematically in Experiment 2 (24 10‐year‐olds, 24 adults) enabled children to grade the speeds adequately in the action conditions only. Adults now produced normative response patterns in both judgment and action. Whether people show linearization biases was thus shown to depend on the interaction of age, task demands and response mode.
Modelling virtual cities dedicated to behavioural animation
Authors: Thomas Gwenola , Donikian Stéphane
Published: December 2004

In order to populate virtual cities, it is necessary to specify the behaviour of dynamic entities such as pedestrians or car drivers. Since a complete mental model based on vision and image processing cannot be constructed in real time using purely geometrical information, higher levels of information are needed in a model of the virtual environment. For example, the autonomous actors of a virtual world would exploit the knowledge of the environment topology to navigate through it. In this article, we present a model of virtual urban environments using structures and information suitable for behavioural animations. Thanks to this knowledge, autonomous virtual actors can behave like pedestrians or car drivers in a complex city environment. A city modeler has been designed, using this model of urban environment, and enables complex urban environments for behavioural animation to be automatically produced.
Visualizing Crowds in Real‐Time
Authors: Tecchia Franco , Loscos Celine , Chrysanthou Yiorgos
Published: December 2004

Real‐time crowd visualization has recently attracted quite an interest from the graphics community and, asinteractive applications become even more complex, there is a natural demand for new and unexplored applicationscenarios. However, the interactive simulation of complex environments populated by large numbers of virtualcharacters is a composite problem which poses serious difficulties even on modern computer hardware. In thispaper we look at methods to deal with various aspects of crowd visualization, ranging from collision detectionand behaviour modeling to fast rendering with shadows and quality shading. These methods make extensive useof current graphics hardware capabilities with the aim of providing scalability without compromising run‐timespeed. Results from a system employing these techniques seem to suggest that simulations of reasonably complexenvironments populated with thousands of animated characters are possible in real‐time.

ACM CSS: I.3.7 Three‐Dimensional Graphics and Realism—Animation
Automatic Hybrid Hierarchy Creation: a Cost‐model Based Approach
Authors: Massó J. P. Molina , López P. González
Published: December 2004

While using hierarchical search structures has been proved as one of the most efficient acceleration techniques when rendering complex scenes, automatic creation of appropriate hierarchies is not solved yet. Well‐known algorithms for automatic creation of bounding volume hierarchies are not enough. Higher performance is achieved by introducing spatial uniform subdivision, although algorithms proposed up to now are not truly automatic, as they need some parameters to be adjusted. In this paper we present a full‐automatic hierarchy creation scheme that structures the scene in a hybrid way, combining bounding volumes and voxel grids in the same tree, selecting the search structure that best fits to each scene region. It uses no parameters at all. This efficient proposal relies on a new cost model that estimates the goodness of a hybrid hierarchy if used for rendering the scene.

ACM CSS: I.3.7 Computer Graphics—Three‐Dimensional Graphics and Realism
Interpolating an Unlimited Number of Curves Meeting at Extraordinary Points on Subdivision Surfaces*
Authors: Nasri Ahmed H.
Published: December 2004

Interpolating curves by subdivision surfaces is one of the major constraints that is partially addressed in the literature. So far, no more than two intersecting curves can be interpolated by a subdivision surface such as Doo‐Sabin or Catmull‐Clark surfaces. One approach that has been used in both of theses surfaces is the polygonal complex approach where a curve can be defined by a control mesh rather than a control polygon. Such a definition allows a curve to carry with it cross derivative information which can be naturally embodied in the mesh of a subdivision surface. This paper extends the use of this approach to interpolate an unlimited number of curves meeting at an extraordinary point on a subdivision surface. At that point, the curves can all meet with either

C
0

or

C
1

continuity, yet still have common tangent plane. A straight forward application is the generation of subdivision surfaces through 3‐regular meshes of curves for which an easy interface can be used.
On the Optimality of Valence‐based Connectivity Coding
Authors: Gotsman Craig
Published: December 2004

We show that the average entropy of the distribution of valences in valence sequences for the class of manifold 3D triangle meshes and the class of manifold 3D polygon meshes is strictly less than the entropy of these classes themselves. This implies that, apart from a valence sequence, another essential piece of information is needed for valence‐based connectivity coding of manifold 3D meshes. Since there is no upper bound on the size of this extra piece of information, the result implies that the question of optimality of valence‐based connectivity coding is still open.
Review article: Movers and Shakers: the Barbarians and the Fall of Rome
Authors: Halsall Guy
Published: December 2004

Books received for review:

The Lombards. By Neil Christie.

The Goths. By Peter Heather.

The End of Roman Britain. By Michael E. Jones.

The Huns. By Edward A. Thompson (revised by P. Heather).
Hostages in the Carolingian world (714–840)
Authors: Kosto Adam J.
Published: December 2004

The medieval hostage (obses) was a form of personal surety, a person deprived of liberty by a second person in order to guarantee an undertaking by a third person. Although they were used in private transactions, they normally appear in the early medieval sources in the context of relations between political entities. Close to seventy distinct hostage episodes are recorded in greater Francia and the Italian Peninsula in the period 714–840. Drawing on this evidence, as well as on the few surviving normative sources that refer to hostages, the present article develops a definition of hostages in the Carolingian period, examines the situations in which they were used, and argues that they must be seen as more than a simple means for securing agreements. In particular, grants of hostages might involve individuals beyond the trio of creditor–debtor–hostage, and they could transcend their immediate guaranteeing function to serve symbolic and political ends. The proper context for the study of hostages emerges as not legal but social and political relations.
Beyond cemetery walls: early medieval funerary topography and Christian salvation
Authors: Effros Bonny
Published: December 2004

The article examines how the topography of the Christian cemetery in Merovingian Gaul mirrored the status which the souls of individuals were believed to occupy in the sphere of the next world. In practice, moreover, the clergy's treatment of Christian corpses was often perceived as determining their fate. Drawing on both literary and material evidence, the article argues that the boundaries established between the faithful and the damned in the Christian cemetery supported the Church's claims to sacral authority in this life and the next.
Can House Prices Remain so High?
Authors: Meen Geoff
Published: December 2004

House prices are rarely out of the headlines in the UK and continue to be a national obsession. But, for an asset that is so important in household portfolios, regrettably, the standard of economic analysis is often extremely poor, ignoring even the most basic economic theory and empirical evidence. In this article, Geoff Meen assesses the dangers of a collapse in house prices. A more dispassionate look at the evidence suggests that, at the national level, there is little evidence of a serious problem. This remains the case when we move to the regional level. However, we would suggest, on the basis of preliminary evidence, that certain areas of London could be over‐valued. If any market is to decline, this would be our first bet. But it does not follow that the rest of the country will also decline.
Democracies and Inefficiency
Authors: Baba S. A.
Published: December 2004

A government‐interest group model is presented. Voters are neither always rationally ignorant nor always fully informed. Voters' information is variable. Unlike other models that assume a vote production function, this model considers the voter's utility and shows how rational voters with limited information can sometimes vote for inefficient policies.

If voters can be informed inexpensively, then democracies are efficient. If the cost of informing voters is prohibitive, then pressure groups efficiently extract rent. If the cost of informing voters is low for efficient direct handouts, but high for inefficient policies, then inefficient redistributions will occur.
Local Government Spending and At‐Large Versus District Representation; Do Wards Result in More “Pork”?
Authors: Southwick, Jr L.
Published: December 2004

The issue of at‐large versus ward representation has recently again become controversial. Wards are argued to better represent minorities, both ethnic and preference. However, an opposing argument is that wards encourage spending. It is suggested that one reason for this is that, with ward representation, a coalition can be put together to exploit other areas of the city. This question is tested empirically and it is found that spending, debt, and taxes are both significantly and substantially higher in cities where ward representatives have greater power than in cities where at‐large representatives have the greater power. It is conjectured that this same effect results in higher state and federal expenditures than would be desired by the majority of voters.
Searching for the Downsian Voter with a Simple Structural Model
Authors: Grant D.
Published: December 2004

Studies of voter turnout consistently find that turnout responds to the closeness of the election, yet it is widely claimed that the probability of casting the deciding vote is too minute to be of consequence. We provide evidence on this puzzle by deriving a structural rational voting model in the form of a relatively simple regression equation, and fitting it to data from a large sample of US congressional elections.
Foreign Aid and International Support as a Gift Exchange
Authors: Lundborg P.
Published: December 2004

Regressions on data from 1948 to 1979 indicate that the US and the Soviet Union used foreign aid to stimulate international political support from the receivers of aid and that aid receivers allocated their political support to stimulate aid from these donors. The regressions are based on a game theoretical model in which aid donors provide aid to reach foreign policy goals and in which aid receivers in return give political support to the donors so as to raise foreign aid. With foreign policy ambitions, aid should be given the countries with low GDP levels, while if altruistic considerations determine aid, countries with low levels of GDP per capita should be the beneficiaries. Since foreign aid to some extent was the result of cold war rivalry, the changes in international relations which occurred with the fall of the Soviet Union, should lower total foreign aid.
Strategic Trade, Competitive Industries and Agricultural Trade Disputes
Authors: Bagwell Kyle , Staiger Robert W.
Published: December 2004

The primary predictions of strategic‐trade theory are not restricted to imperfectly competitive markets. Indeed, these predictions emerge in a natural three‐country extension of the traditional theory of trade policy in competitive markets, once the theory is augmented to allow for politically motivated governments, so that the sign of export policy may be converted from tax to subsidy. This suggests that the ongoing agricultural trade disputes may be best interpreted from the perspective of strategic‐trade theory. In fact, these disputes may offer the most important example yet of strategic‐trade theory.
Economic transition and elections in Poland1
Authors: Jackson John E. , Klich Jacek , Poznańska Krystyna
Published: December 2004

Poland's economic and political transition, one of the most successful, has depended very heavily on job creation in new firms to replace the jobs lost in the formerly state‐owned enterprises. This paper uses survey and aggregate data from three Polish elections to suggest that these de novo firms, the individuals they employ, and the residents in the local areas where they exist become an important constituency supporting pro‐reform political parties and constraining the actions of parties less sympathetic to the reforms. The creation of this political constituency helps explain how countries can successfully pursue both economic and political reforms.

JEL classification: D72, P26.
Gross job flows in Ukraine
Authors: Konings Jozef , Kupets Olga , Lehmann Hartmut
Published: December 2004

This paper documents and analyses gross job flows and their determinants in Ukraine using a dataset of more than 2200 Ukrainian firms operating in manufacturing and non‐manufacturing for the years 1998–2000. Job destruction dominates job creation in both 1999 and 2000. Another clear‐cut result of our analysis is the strong positive effect of new private firms on net employment growth. We also find an inverse relationship between job reallocation and size for both manufacturing and non‐manufacturing, while only in the latter sector is employment growth inversely related with size. The main focus of the paper is the effect of trade flows on employment adjustment in manufacturing. Our results show that both employment growth and job reallocation at the firm and two‐digit sector level are affected by strong exposure to import competition and product market competition in export markets. These effects are more pronounced when we consider trade flows to the world at large and to the EU than when the analysis is based on trade flows to the CIS.

JEL Classifications: E24, F14, J63, P23.
The causes and consequences of sector‐level job flows in Poland*
Authors: Warzynski Frédéric
Published: December 2004

We look at the determinants and consequences of job reallocation in the 22 2‐digit sectors of the manufacturing industry in Poland over the period 1995–99. We find that import competition and a competitive market structure (weak concentration) have a positive and significant effect on job reallocation. Moreover, higher job reallocation is associated with higher labour productivity growth in some specifications. This confirms implications from neo‐Schumpeterian growth models: one channel through which competition might positively affect growth is through the reallocation of scarce resources from declining firms to rising ones.

JEL Classifications: F16, J24, J6, O3, P3.
High‐tech Start‐ups in Europe: The Effect of Regulatory Competition on the Emergence of New Business Forms
Authors: McCahery Joseph A. , Vermeulen Erik P. M.
Published: December 2004

This paper will examine the theoretical arguments for and against the importance of new business forms for the growth of start‐ups. Part I briefly reviews the recent history of business organisational law and reform within Europe. Our review of extant European business forms reveals that the absence of new business entities (and structural reforms) may be due to status quo bias and other network effects. Turning to the importance of new business forms, Part II addresses the question which organisational and legal structures are favourable for the growth of start‐ups. It is suggested that the introduction of an efficient organisational form for start‐ups is crucial to further stimulate the development of a successful venture capital market in Europe. In Part III we give consideration to the possibility of developing new business forms, based on US mechanisms, which could lead to an increase in the level of high‐tech start‐ups. The prospect for the emergence of new business forms depends in part on the removal of legal and non‐legal barriers. The final section evaluates whether we can project a pattern of regulatory competition in the business organisation context that could prompt lawmakers to innovate by introducing new legal entities.
Maximum Residue Limits of Veterinary Medicinal Products and Their Regulation in European Community Law
Authors: Ancuceanu Robert
Published: December 2004

This paper proposes a legal analysis of a legal and empirical tool (maximum residue limits (MRLs)) designed to protect the consumers of animal foodstuffs, as it is regulated in European Community law. After introducing the concept of MRLs in its legal context, MRLs are defined and the need for harmonisation in this field is explained. Then the main rules governing the establishment of MRLs at a Europe‐wide level are expounded, an important place being devoted to some problems occurred in the cases decided by the European Court of Justice: is it possible to establish an MRL only for certain therapeutic indications? What about the intention of placing on the market in the establishment of an MRL? Is the procedure for the establishment of MRLs a tight or lax one? The answer to some of these questions involves more general aspects of European Community law.
Constitutional Irresolution: Law and the Framing of Civil Society
Authors: Christodoulidis Emilios
Published: December 2004

Abstract: Against the constitutional optimism that pervades our political rationality, I will argue the case for a disorganised civil society, genuinely plural, resistant to dominant representations that call it into line and thus undercut its radical potential. I will explore some of the more adventurous and persuasive such attempts to argue for an inclusive constitutionalism, one that supposedly reaches out to civil society and in order to do so relaxes the rigidity of its own terms, to harbour and host the diversity it aspires to represent. I will argue that these attempts at inclusion create constitutional irresolutions either forcing impossible demands on constitutionalism or dispelling the disorganisation it is meant to give expression to. I will then argue that in spite of the inability to capture them as constitutional moments, politics of ‘pure presence’ and real self‐determination are possible, and against constitutional mystifications, resistance might find its opportunity in praxis, understood in the language of praxis philosophy (more specifically the work of Antonio Negri).
Moral Traditionalism and the Kinds of School‐Based Health Center Services Offered in the United States*
Authors: Williams Arthur R. , Litvak Irina , Moriarty James P.
Published: December 2004

Objective.An earlier article published in this journal reports that morality politics and political economy variables jointly affect the offering of both sexual and contraceptive health services at school‐based health centers (SBHC). Data are reanalyzed cognizant of structural linkages: general health → sexual health → contraceptive services.

Methods.To correct for spurious correlations in the earlier article, three ordinary least squares regressions with robust standard errors are estimated.

Results.General health services fit a political economy model. Sexual health services are associated with morality politics. The offering of contraceptive services is influenced by the number of sexual health services offered and urbanism, not directly by moral traditionalism and political economy variables.

Conclusions.Opponents and advocates of school health services are likely to engage in political strategies that address characteristics of the arenas in which different types of services are offered.
Gray Peril or Loyal Support? The Effects of the Elderly on Educational Expenditures*
Authors: Berkman Michael B. , Plutzer Eric
Published: December 2004

Objectives. Do large concentrations of elderly represent a “gray peril” to maintaining adequate educational expenditures? The gray peril hypothesis is based on an assumption of instrumental self‐interest in political behavior. In contrast, we argue that loyalty to community schools competes with economic self‐interest and that older citizens are heterogeneous in their preferences.

Methods. We test these arguments and their implications for public school finance using a data set of more than 9,000 school districts.

Results. The data show that longstanding older residents represent a source of support for educational expenditures while elderly migrants lower spending. Further, this divide among the elderly and their impact on policy outputs depends on how states finance local public education and on aspects of state and local tax policy.

Conclusions. Elderly concentrations are a financial asset for a school district unless the senior community includes a large number of new arrivals. The design of tax policy can have enormous impact on the depth of political cleavages and their ultimate impact on public policy. The results are consistent with the idea that loyalty—an emotional bond between residents and their community's institutions—competes with and often trumps instrumental self interest.
Family Resources, Gender, and Immigration: Changing Sources of Hong Kong Educational Inequality, 1971–2001*
Authors: Post David
Published: December 2004

Objective.This study gauged the impact of government‐led educational expansion on Hong Kong's social stratification over a 30‐year period. The historically close state control over school supply in Hong Kong allows us to test the effectiveness of public policy in changing the transmission of advantages across generations.

Methods.I analyzed household‐level census data from 1971, 1981, 1991, and 2001. Interviews and documents were also used to illuminate reasons for trends during this period.

Results.There was a diminishing role of family resources and gender on access to all levels of schooling until 1991. From 1991 through 2001, however, there was a reversal of this trend at the postsecondary level, as access to university education became more dependent on family resources. In addition, new immigrants from mainland China were at an increased disadvantage.

Conclusions.Hong Kong's current plan to create a second tier of self‐supporting postsecondary institutions will exacerbate the tendency toward unequal university access, and is also likely to segregate new arrivals from mainland China.
The Interplay Between Social and Cultural Determinants of School Effort and Success: An Investigation of Chinese‐Immigrant and Second‐Generation Chinese Students' Perceptions Toward School*
Authors: Kaufman Julia
Published: December 2004

Objective. Educational research suggests that close‐knit, supportive immigrant communities can encourage students' school success; however, less agreement exists about why students outside of those communities—particularly in urban areas—do not always do as well in school, even when those students perceive themselves to be working as hard as their higher‐performing immigrant peers. This article explores the relationship between Chinese‐immigrant and second‐generation Chinese students' perceptions and social/cultural factors that influence their lives in a large urban school.

Methods. Longitudinal interviews with students, as well as observations at the school, took place from September 2000 to May 2001.

Results. Chinese immigrants in this study are motivated to work hard and value demanding teachers, difficult curriculum, and discipline more than their second‐generation Chinese peers; the second‐generation students talk of wanting more entertaining, knowledgeable teachers while not being willing or able to work as hard for school success.

Conclusions. These findings indicate that differences in students' perceptions of their own effort and success in school may depend greatly on the social environment in which students find themselves, as well as the culturally‐driven actions available within those environments.
Low‐Income Students and College Attendance: An Exploration of Income Expectations*
Authors: Rouse Cecilia Elena
Published: December 2004

Objectives. Some have hypothesized that unrealistic expectations regarding their futures may explain the weak link between expectations and realizations among low‐income (particularly minority) youth. Unfortunately, there is little evidence characterizing students' expectations around the time that they make college decisions that would allow one to study this hypothesis.

Methods. In this exploratory article, I analyze data on income expectations from a small sample of low‐income minority high school seniors in Baltimore City, MD; and use data from Dominitz and Manski's sample of higher‐income white students in Madison, WI, and the NELS88 for comparisons.

Results. I find little evidence that the income expectations of lower‐income minority students are so different from those of higher‐income students. Rather, the expected returns to postsecondary education appear similar between the two samples of high school seniors. Analysis of a nationally representative sample of high school seniors suggests that lower‐income students do not place less weight on expected economic returns to college when making their plans than do more advantaged students, although low‐income students are less able to translate their college plans into actual college attendance.

Conclusions. These results suggest that differing income expectations do not explain the weaker relationship between expectations and educational attainment among low‐income students.
Effect of low‐dose warfarin on D‐dimer levels during sickle cell vaso‐occlusive crisis: a brief report
Authors: Ahmed Shahid , Siddiqui Anita K. , Iqbal Uzma , Sison Cristina P. , Shahid Rabia K. , Sheth Manish , Patel Dilip V. , Russo Linda A.
Published: December 2004

Objective : To evaluate the activation of clotting systems in patients with sickle cell disease (SCD) by measuring the plasma D‐dimer level and to determine the effect of low‐dose warfarin on D‐dimer level during vaso‐occlusive crisis.

Methods : Plasma D‐dimer level was measured in 65 blood samples of 37 adult patients with SCD who were hospitalized for vaso‐occlusive painful crisis. D‐dimer level of patients who were on low‐dose warfarin was compared with those patients who were not on any anticoagulation treatment. Analysis of variance (anova) was carried out to determine factors significantly associated with low D‐dimer level in patients with SCD. The following factors were included in the anova model; warfarin, homozygous hemoglobin S, history of blood transfusion in past 3 months, hydroxyurea, hemoglobin S%, hemoglobin F%, white blood cell counts, hemoglobin level, platelet count, and plasma fibrinogen level.

Results : Overall median D‐dimer level in 65 samples was 2.7 μg fibrinogen equivalent units (FEU)/mL (0.34–4). Patients who were on low‐dose warfarin had a median D‐dimer level of 0.81 μg FEU/mL (0.34–1.8) compared with 3.1 μg FEU/mL (0.94–4) in those patients who were not on anticoagulation treatment. Using anova to model D‐dimer levels, only warfarin was significantly correlated with low D‐dimer levels after controlling for other variables.

Conclusions : Patients with SCD during vaso‐occulsive painful crisis have an elevated D‐dimer level. Low‐dose anticoagulation treatment is associated with a significant reduction in the D‐dimer levels.
A review of post‐trachelectomy isthmic and vaginal smear cytology
Authors: Singh N. , Titmuss E. , Chin Aleong J. , Sheaff M. T. , Curran G. , Jacobs I. J. , Shepherd J. H.
Published: December 2004

Currently in the UK cervical cancer has a peak incidence in women aged 35–39. Fertility‐conserving surgical treatment by radical trachelectomy is established in the management of early disease. This study aimed at establishing the value of cytology in follow‐up after trachelectomy. The cytological features of isthmic‐vaginal smears post‐trachelectomy for cervical cancer are presented together with a discussion of relevant clinical issues. One hundred and ninety seven smears from 32 women were reviewed. Two of the 32 patients developed pelvic recurrences. In both cases recurrence was detected cytologically long before development of a clinical or radiological abnormality. There is, however, a potential for overcall due to the presence of endometrial cells. These were present in large numbers and varying configurations in 58% of smears and led to a false positive report of malignancy in 2% of smears. The rate of referral for a cytologist opinion was significantly higher in smears containing endometrial cells (26%) than those without (13%). While all smears contained squamous cells, 41% contained squamous cells only and it is proposed that such smears should be reported as unsatisfactory in the first 2 years after surgery and negative thereafter, although the absence of glandular cells should be recorded. When an abnormality is reported, smear review and multidisciplinary discussion may avoid unnecessary investigations.
Biliary brushing cytology
Authors: Selvaggi S. M.
Published: December 2004

Biliary tract brush specimens are fast becoming the method of choice in the evaluation of patients who present with biliary tract strictures. Although the specificity is high, sensitivity rates for the detection of malignancy are generally low on cytological sampling. New liquid‐based preparations and ancillary tests have emerged with the intent of addressing this issue. This review focuses on the current schemata used in the diagnosis of biliary tract lesions and the current available modalities which aid in the diagnosis of cholangiocarcinoma.
Rapid review in cervical cytology: a retrospective review of cases detected on rapid review within a DGH cytology department and subsequent outcome
Authors: Wilson N. J. , Molyneux A. J.
Published: December 2004

We retrospectively reviewed smears detected by rapid review within a district general hospital (DGH) laboratory over a period of 33 months and the subsequent histological or cytological outcome. Sixty‐three cases had adequate follow‐up data: 32 subsequently had two negative smears and 31 had a histological abnormality on subsequent biopsy. Twenty were high‐grade lesions (CIN2, CIN3 or a glandular lesion) and eight of these were preceded by a low‐grade smear abnormality. We reviewed and compared the pattern and distribution of smear abnormalities in these 63 cases. Abnormalities were often present within few cells (76%, n = 48 with 50 abnormal cells or less) or in micro‐biopsies (27%, n = 17). There was no statistical difference in the pattern and distribution of smear abnormality between the rapid review‐detected smears with a biopsy‐proven abnormality and those with negative follow‐up smears. Overall, the positive predictive value for high‐grade CIN detected by rapid review (75%) was within NHSCSP achievable standards targets. This review of rapid review‐detected abnormalities and the biopsy and cytological follow‐up reiterates the importance of the method in cervical screening.
Accuracy of touch imprint cytology in diagnosing lung cancer
Authors: Paulose R. R. , Shee C. D. , Abdelhadi I. A. , Khan M. K.
Published: December 2004

A 3‐year study assessed the diagnostic accuracy of touch imprint smears in the diagnosis of lung cancer. Touch imprint smears were prepared from 90 computerized tomographic‐guided core needle lung biopsies. Cytological diagnosis of touch imprint smears were correlated with the histological diagnosis of the corresponding core needle biopsy specimen, which was taken as the gold standard. The sensitivity, specificity, positive predictive value and negative predictive value of imprint smear results were 89%, 100%, 100% and 68%, respectively. There were no false positives, and all patients with small cell lung cancer were correctly diagnosed with this technique. Imprint cytology can be used to provide a rapid, preliminary diagnosis of lung cancer.
Seed beetle survivorship, growth and egg size plasticity in a paloverde hybrid zone
Authors: FOX CHARLES , WADDELL KIM , DES LAURIES JAMES , MOUSSEAU TIMOTHY
Published: December 2004

1. Although numerous studies have examined the ecology of plant resistance to herbivores and the distribution of herbivores within plant hybrid zones, few have examined how plant hybridization influences herbivore growth, development, or life history. The experiment reported here examines variation in survivorship, development time, and final adult body size of Stator limbatus reared on seeds of parental and hybrid Cercidium floridum‐×‐C. microphyllum trees from a paloverde hybrid zone in eastern California. Because S. limbatus exhibits egg size plasticity in response to host species, the size of eggs that females lay on hybrid and parental plants is also examined.

2. The hypotheses (a) that seeds of hybrid trees are intermediate between those of the two parental species in their resistance to penetration by S. limbatus larvae; (b) that seeds of hybrid trees are intermediate in their suitability for the growth of larvae that successfully penetrate the seed‐coat; (c) that female S. limbatus can distinguish between hybrid trees and pure‐bred trees, as quantified by the size of eggs they lay on seeds of each taxon, and (d) that female S. limbatus can distinguish among individual hybrid trees, are tested.

3. On average, S. limbatus survivorship was lower, development time longer, and emergence body mass lower on seeds of C. floridum than on seeds of C. microphyllum. Seeds of hybrid trees were, on average (across trees), intermediate between seeds of the parental species in the resistance of their seed‐coats to penetration by S. limbatus larvae and in their suitability for larval growth. Individual hybrid trees also varied in the resistance of their seeds to, and the suitability of their seeds for, S. limbatus larvae.

4. Female S. limbatus laid significantly larger eggs on seeds of C. floridum than on seeds of C. microphyllum, and, on average, intermediate size eggs on hybrid trees. The size of eggs laid by females also varied among hybrid trees, with females laying C. floridum‐sized eggs on some trees, and C. microphyllum‐sized eggs on other trees. These results suggest that females have at least some ability to distinguish among hybrid trees, but there was no evidence that females laid larger eggs on poorer quality hybrid trees.
Oro‐cecal transit time: influence of a subsequent meal
Authors: Priebe M. G. , Wachters‐Hagedoorn R. E. , Stellaard F. , Heiner A. M. , Elzinga H. , Vonk R. J.
Published: December 2004

Background  Small intestinal and oro‐cecal transit time (OCTT) is determined for clinical diagnostics and research purposes. Experimental protocols used vary with respect to the inclusion of a subsequent meal during the test period. This study was conducted to elucidate whether the ingestion of a subsequent meal during the test period influences the OCTT of the test meal.

Materials and methods  The OCTT of a liquid test meal, measured with the lactose‐[13C]ureide breath test, was compared between four groups of healthy volunteers (n = 36) who consumed the subsequent meal at different time points. Also, the OCTT was determined twice in eight subjects; a subsequent meal was ingested after 180 min (test A) and after 360 min (test B).

Results  An apparently meal‐related increase in median OCTT was observed. The OCTT of the eight volunteers measured in test A (210; 210–349 median; quartiles) was significantly shorter than that found in test B (345; 300–375 min, P = 0·016). As result of the ingestion of the subsequent meal at 180 min the OCTT was shortened by 90; 64–116 min in 7/8 subjects.

Conclusion  These data indicate that the ingestion of a subsequent meal affects the OCTT of a liquid test meal. This phenomenon could be explained by the increased intestinal motility in response to a meal, and should be taken into account when designing protocols for measurements of the OCTT and in the interpretation of small intestinal absorption studies.
A spatially explicit, individual‐based model to assess the role of estuarine nurseries in the early life history of North Sea herring,Clupea harengus
Authors: MAES JOACHIM , LIMBURG KARIN E. , VAN DE PUTTE ANTON , OLLEVIER FRANS
Published: December 2004

Herring (Clupea harengus) enter and remain within North Sea estuaries during well‐defined periods of their early life history. The costs and benefits of the migrations between offshore spawning grounds and upper, low‐salinity zones of estuarine nurseries are identified using a dynamic state‐variable model, in which the fitness of an individual is maximized by selecting the most profitable habitat. Spatio‐temporal gradients in temperature, turbidity, food availability and predation risk simulate the environment. We modeled predation as a function of temperature, the optical properties of the ambient water, the time allocation of feeding and the abundance of whiting (Merlangius merlangus). Growth and metabolic costs were assessed using a bioenergetic model. Model runs using real input data for the Scheldt estuary (Belgium, The Netherlands) and the southern North Sea show that estuarine residence results in fitter individuals through a considerable increase in survival probability of age‐0 fish. Young herring pay for their migration into safer estuarine water by foregoing growth opportunities at sea. We suggest that temperature and, in particular, the time lag between estuarine and seawater temperatures, acts as a basic cue for herring to navigate in the heterogeneous space between the offshore spawning grounds at sea and the oligohaline nursery zone in estuaries.
Clupeoid larval growth and plankton production in the Benguela upwelling system
Authors: SKOGEN MORTEN D.
Published: December 2004

Upwelling is a characteristic feature of the Benguela system. Strong upwelling leads to high primary production, which, in turn, supports large biomass of higher trophic levels. To analyse intra‐, interannual and decadal variability of fish recruitment, growth, and distribution, different methods to quantify this upwelling have been used. In the present work, an upwelling index, modelled diatom primary production, based on outputs from a numerical model for the Benguela upwelling system, is proposed. Upwelled water brings large amounts of nutrients into the euphotic zone and this supports primary productivity, which can be considered a preconditioner for the zooplankton that clupeoid larvae feed on. Therefore, it is assumed that high upwelling gives the potential for good feeding conditions for these larvae. This fact has motivated the use of the modelled index for upwelling intensity as a proxy for food availability and an investigation of the interannual variability of observed mean individual weight of Cape anchovy (Engraulis capensis) and sardine (Sardinops sagax) recruits. The study shows that the mean Cape anchovy recruit weight has a linear relationship with upwelling activity along the transport route (from the spawning to the nursery areas) and inside the nursery areas, while sardine have an Optimal Environmental Window (OEW) relationship to the upwelling on the transport route. A possible explanation for these observed differences is the prey the larvae feed on and the change in the plankton community as a function of upwelling activity.
Composition of fish communities in German lakes as related to lake morphology, trophic state, shore structure and human‐use intensity
Authors: Mehner Thomas , Diekmann Markus , Brämick Uwe , Lemcke Roland
Published: December 2004

1. Previous comparative analyses of fish communities in European lakes have mainly focused on the response of community composition to eutrophication. In addition, frequently only one or two lake habitats have been sampled.

2. Here, we present fish community data from 67 lakes in north‐east Germany. Fish abundance was estimated in littoral, benthic and pelagic habitats from which a composite parameter indicating lake‐wide relative species abundances was derived. This parameter was used in group comparisons and non‐metric ordination procedures to explore, among 40 lake habitat descriptors sampled, those most important in structuring community composition.

3. Fish community composition was mainly determined by maximum and mean depth, chlorophyll a content and lake volume. The impact of anthropogenic alterations of shore structure and human‐use intensity of lakes were of minor importance. The dominant fish species were vendace Coregonus albula, perch Perca fluviatilis, smelt Osmerus eperlanus and several cyprinids (roach Rutilus rutilus, bream Abramis brama, white bream Abramis bjoerkna and bleak Alburnus alburnus).

4. A response of relative species abundance to lake productivity could be demonstrated for small perch, ruffe and bream. However, when the relationship between lake morphology and productivity was controlled for, differences in species abundances were not longer attributable to differences in productivity, but to maximum lake depth.

5. This suggests that there are two distinct fish community types in Germany, namely the cold‐water community with vendace and perch inhabiting deeper lakes, and the warm‐water cyprinid community inhabiting more shallow lakes. The previously established conceptual model of a community succession from salmonids through perch to cyprinids with increasing eutrophication is hence not continous, but includes a switch between two lake and fish community types.
Comment on drag and reconfiguration of macrophytes
Authors: Sukhodolov Alexander
Published: December 2004

1. The experimental approach of Sand‐Jensen (2003), designed to examine quantitatively the response of freshwater macrophytes to physical forcing by moving water, is discussed. Specifically, it is emphasised that neglecting the principal difference between the wetted and the frontal area of the aquatic plants necessarily provides unacceptably large errors in estimates of drug coefficient.

2. The empirical methodology employed in the study to generalise the data (Sand‐Jensen, 2003) suffers from a dimensional problem and can potentially lead to misleading conclusions. The methodology could be improved by using the relationship between dimensionless values of drag coefficient and dimensionless Reynolds number.
Plankton dynamics in a tropical floodplain lake: fish, nutrients, and the relative importance of bottom‐up and top‐down control
Authors: Rejas Danny , Declerck Steven , Auwerkerken Johan , Tak Paulus , Meester Luc De
Published: December 2004

1. Two enclosure experiments were carried out in Laguna Bufeos, a neotropical várzea lake located in the floodplain of River Ichilo (Bolivia). The experiments aimed (i) to assess the relative importance of bottom‐up and top‐down control on the plankton community, (ii) to assess the relative impact of direct and indirect effects of planktivorous fish on the zooplankton, and (iii) to attempt to identify the mechanisms responsible for these effects.

2. During the first experiment, bottom‐up control seemed to dominate the planktonic food web. Compared with fishless enclosures, oxygen concentrations, chlorophyll a levels and the population densities of all cladoceran zooplankton taxa increased in enclosures with fish. Birth rates of Moina minuta, the dominant taxon, were substantially higher in the presence than in the absence of fish, whereas death rates did not differ between treatments. These results are the first to suggest that the positive effects of fish on crustacean zooplankton via effects on nutrient cycling and the enhancement of primary production can compensate for losses because of fish‐related mortality.

3. During the second experiment, the direction of control appeared to vary between trophic levels: the phytoplankton appeared to be bottom‐up controlled whereas the zooplankton was mainly top‐down controlled. Chlorophyll a concentrations were enhanced by both fish and nutrient additions. The majority of the zooplankton taxa were reduced by the presence of fish. Birth rates of most cladoceran taxa did not differ between treatments, whereas death rates were higher in the enclosures with fish than in the fishless enclosures. Bosminopsis deitersi reached higher densities in the presence of fish, probably because of a release from predation by Chaoborus.

4. We convincingly showed strong deviations from trophic cascade‐based expectations, supporting the idea that trophic cascades may be weak in tropical lakes.
Temporal stability of pond zooplankton assemblages
Authors: Steiner Christopher F.
Published: December 2004

1. A large body of recent theory has recently developed focused on the relationship between the species diversity of competitor assemblages and the temporal stability of total competitor biomass. Many of these models predict that stability can increase with increasing diversity.

2. To explore natural relationships between zooplankton taxonomic diversity and temporal stability of total zooplankton biomass, 18 fishless, permanent ponds located in southern Michigan were surveyed over a 5 month period during a single growing season.

3. Results showed that temporal variability in total zooplankton biomass (measured as the coefficient of variation or CV) decreased with increasing mean zooplankton taxonomic richness. Thus, temporal stability increased with increasing taxonomic richness, consistent with theoretical predictions.

4. Decreases in the CV appeared to be because of portfolio effects (statistical averaging of species’ biomass fluctuations) rather than negative covariances among zooplankton taxa.

5. The CV of zooplankton biomass was also related to several environmental variables, suggesting that taxonomic richness may not be the only mediator of biomass stability. The CV decreased with increasing relative abundance of grazer‐resistant algae (algae >35 μm in size) and the CV increased with increasing pond productivity.