bluuebunny/crossref_metadata_2025 huggingface dataset:
Annual to interannual temperature variability in the Caribbean during the Maunder sunspot minimum
Authors: Haase‐Schramm Alexandra , Böhm F. , Eisenhauer A. , Garbe‐Schönberg D. , Dullo W.‐C. , Reitner J.
Published: November 2005

We reconstruct Caribbean seawater temperatures from sclerosponge Sr/Ca ratios using a specimen of Ceratoporella nicholsoni that grew at 20 m below sea level in a reef cave at Jamaica. We sample the time interval from 1620 to 1745 A.D. with almost monthly resolution. This interval includes the Maunder sunspot minimum, one of the coldest periods of the Little Ice Age. Reconstructed annual temperature amplitudes are on the order of about 1°C. The mean growth rate calculated from the annual Sr/Ca variations corresponds perfectly with U‐Th‐based growth rates. We find that the interannual climate variability is determined by El Niño–Southern Oscillation and by a decadal signal, most likely originating from the tropical North Atlantic. On a multidecadal timescale the Maunder Minimum is characterized by a 1°–2°C cooling and reduced amplitudes of the interannual and decadal temperature variations.
Surface electric fields and geomagnetically induced currents in the Scottish Power grid during the 30 October 2003 geomagnetic storm
Authors: Thomson Alan W. P. , McKay Allan J. , Clarke Ellen , Reay Sarah J.
Published: November 2005

A surface electric field model is used to estimate the UK surface E field during the 30 October 2003 severe geomagnetic storm. This model is coupled with a power grid model to determine the flow of geomagnetically induced currents (GIC) through the Scottish part of the UK grid. Model data are compared with GIC measurements at four sites in the power network. During this storm, measured and modeled GIC levels exceeded 40 A, and the surface electric field reached 5 V/km at sites in the United Kingdom (compared with quiet‐time levels of less than 0.1 V/km). The electric field and grid models now form part of a GIC monitoring, analysis, and warning software package with Web interface, developed for use by the grid operator. This package also contains a daily geomagnetic activity forecast service, a solar wind shock detector for geomagnetic storm warning, and a near‐real‐time geomagnetic data stream for storm monitoring.
Gender differences in the slow delayed (IKs) but not in inward (IK1) rectifier K+currents of canine Purkinje fibre cardiac action potential: key roles forIKs,β‐adrenoceptor stimulation, pacing rate and gender
Authors: Abi‐Gerges Najah , Small Ben G , Lawrence Chris L , Hammond Tim G , Valentin Jean‐Pierre , Pollard Chris E
Published: November 2005

As the beagle dog is a commonly used preclinical species to test the effects of new drugs on cardiac repolarisation and Purkinje fibres have become an establishedin vitropreparation to assess the effects of these new drugs on action potential duration (APD), the main aim of this study was therefore to evaluate the relative contribution of the inward (IK1) and slow delayed (IKs) rectifier cardiac K+currents to action potential repolarisation in beagle Purkinje fibres under three different experimental conditions: (i) selective block ofIK1with BaCl2, (ii) selective block ofIKswith (−) chromanol 293B under basal conditions and (iii) selective block ofIKsduringβ‐adrenoceptor stimulation. Furthermore, the dependence of this contribution on gender and pacing rate was investigated. Microelectrode techniques were employed to measure APD in Purkinje fibres from adult female and male dogs.

At stimulation rates of 3.33, 1.0 and 0.2 Hz, the degree of prolongation of APD evoked by BaCl2(10 μM) was comparable in fibres from female and male dogs.

At the same stimulation rates, 10 μM(−) chromanol 293B did not change the APD in fibres from female and male dogs.

Duringβ‐adrenoceptor stimulation with 0.1 μMisoproterenol, an APD prolonging effect of (−) chromanol 293B was detected.

In the presence of isoproterenol, action potentials in fibres from male dogs get shorter when changing the stimulation rate from 1.0 to 0.2 Hz, while the opposite is seen in fibres from female dogs. This alteration was completely reversed by (−) chromanol 293B.

In conclusion, our findings confirm thatβ‐adrenoceptor stimulation is one condition where there may be an increased role ofIKsin action potential repolarisation. Gender differences in the autonomic modulation ofIKscould be a contributing factor to the reported increased susceptibility of female hearts to arrhythmias.

British Journal of Pharmacology(2006)147, 653–660. doi:10.1038/sj.bjp.0706491
Comparison of HERG channel blocking effects of various β‐blockers – implication for clinical strategy
Authors: Kawakami Kazunobu , Nagatomo Toshihisa , Abe Haruhiko , Kikuchi Kan , Takemasa Hiroko , Anson Blake D , Delisle Brian P , January Craig T , Nakashima Yasuhide
Published: November 2005

β‐Blockers are widely used in the treatment of cardiovascular diseases. However, their effects on HERG channels at comparable conditions remain to be defined. We investigated the direct acute effects of β‐blockers on HERG current and the molecular basis of drug binding to HERG channels with mutations of putative common binding site (Y652A and F656C).

β‐Blockers were selected based on the receptor subtype. Wild‐type, Y652A and F656C mutants of HERG channel were stably expressed in HEK293 cells, and the current was recorded by using whole‐cell patch‐clamp technique (23°C).

Carvedilol (nonselective), propranolol (nonselective) and ICI 118551 (β2‐selective) inhibited HERG current in a concentration‐dependent manner (IC50 0.51, 3.9 and 9.2 μM, respectively). The IC50 value for carvedilol was a clinically relevant concentration. High metoprolol (β1‐selective) concentrations were required for blockade (IC50 145 μM), and atenolol (β1‐selective) did not inhibit the HERG current.

Inhibition of HERG current by carvedilol, propranolol and ICI 118551 was partially but significantly attenuated in Y652A and F656C mutant channels. Affinities of metoprolol to Y652A and F656C mutant channels were not different compared with the wild‐type.

HERG current block by all β‐blockers was not frequency‐dependent.

Drug affinities to HERG channels were different in β‐blockers. Our results provide additional strategies for clinical usage of β‐blockers. Atenolol and metoprolol may be preferable for patients with type 1 and 2 long QT syndrome. Carvedilol has a class III antiarrhythmic effect, which may provide the rationale for a favourable clinical outcome compared with other β‐blockers as suggested in the recent COMET (Carvedilol Or Metoprolol European Trial) substudy.

British Journal of Pharmacology (2006) 147, 642–652. doi:10.1038/sj.bjp.0706508
Control of myelination in Schwann cells: a Krox20 cis‐regulatory element integrates Oct6, Brn2 and Sox10 activities
Authors: Ghislain Julien , Charnay Patrick
Published: November 2005

Myelination in Schwann cells is governed by several transcription factors, including the POU proteins Oct6 and Brn2, the high mobility group protein Sox10 and the zinc‐finger protein Krox20. How the function of these factors is integrated in the control of myelination has not been established. Previously, we identified an enhancer element controlling Krox20 expression throughout myelination in Schwann cells. In this paper, cell culture experiments were combined with transgenesis to identify transcription factors acting directly upstream of Krox20. The results show that during the promyelin–myelin transition, Krox20 expression is directly activated by Oct6 and Brn2 acting on this enhancer. In addition, the enhancer‐dependent synergism between these POU proteins and Sox10 suggests that Krox20 expression requires this combination of factors. These results resolve previous controversy concerning the mechanism of action of Oct6 and Brn2 during myelination and provide an explanation for myelin deficiencies in Waardenberg–Hirschsprung disease patients whereby Sox10 mutations could lead to a loss of Krox20 expression.
Repression of polymerase I‐mediated gene expression at Trypanosoma brucei telomeres
Authors: Glover Lucy , Horn David
Published: November 2005

The African trypanosome, Trypanosoma brucei, is a flagellated pathogenic protozoan that branched early from the eukaryotic lineage. Unusually, it uses RNA polymerase I (Pol I) for mono‐telomeric expression of variant surface glycoprotein (VSG) genes in bloodstream‐form cells. Many other subtelomeric VSG genes are reversibly repressed, but no repressive DNA sequence has been identified in any trypanosomatid. Here, we show that artificially seeded de novo telomeres repress Pol I‐dependent gene expression in mammalian bloodstream and insect life‐cycle stages of T. brucei. In a telomeric VSG expression site, repression spreads further along the chromosome and this effect is specific to the bloodstream stage. We also show that de novo telomere extension is telomerase dependent and that the rate of extension correlates with the expression level of the adjacent gene. Our results show constitutive telomeric repression in T. brucei and indicate that an enhanced, developmental stage‐specific repression mechanism controls antigenic variation.
The role of AtMSH2 in homologous recombination in Arabidopsis thaliana
Authors: Emmanuel Eyal , Yehuda Elizabeth , Melamed‐Bessudo Cathy , Avivi‐Ragolsky Naomi , Levy Avraham A
Published: November 2005

During homologous recombination (HR), a heteroduplex DNA is formed as a consequence of strand invasion. When the two homologous strands differ in sequence, a mismatch is generated. Earlier studies showed that mismatched heteroduplex often triggers abortion of recombination and that a pivotal component of this pathway is the mismatch repair Msh2 protein. In this study, we analysed the roles of AtMSH2 in suppression of recombination in Arabidopsis. We report that AtMSH2 has a broad range of anti‐recombination effects: it suppresses recombination between divergent direct repeats in somatic cells or between homologues from different ecotypes during meiosis. This is the first example of a plant gene that affects HR as a function of sequence divergence and that has an anti‐recombination meiotic effect. We discuss the implications of these results for plant improvement by gene transfer across species.
The KSHV oncoprotein vFLIP contains a TRAF‐interacting motif and requires TRAF2 and TRAF3 for signalling
Authors: Guasparri Ilaria , Wu Hao , Cesarman Ethel
Published: November 2005

Primary effusion lymphomas (PELs) characterized by infection with the Kaposi's sarcoma herpesvirus (KSHV; also called human herpesvirus 8) depend on the expression of the viral FADD‐like interleukin‐1‐β‐converting enzyme (FLICE)/caspase‐8‐inhibitory protein (vFLIP) for their survival. This effect is achieved by activation of the transcription factor nuclear factor‐κB (NF‐κB). Tumour necrosis factor (TNF) receptor‐associated factors (TRAFs) are direct mediators of NF‐κB signalling by TNF family receptors and the Epstein–Barr virus oncoprotein latent membrane protein 1 and so we assessed the role of TRAFs in signalling by vFLIP. Here, we report the identification of a TRAF‐interacting motif (PYQLT) in vFLIP, which is not present in other FLIP molecules. We show that vFLIP directly binds to TRAF2 in vitro and in PEL cells. TRAF2 and TRAF3 are required for induction of NF‐κB and associated cell survival, as well as Jun amino‐terminal kinase phosphorylation by vFLIP, whereas TRAF1, TRAF5 and TRAF6 are dispensable. Mutations in the P93 or Q95 amino acids within the TRAF‐interacting motif of vFLIP abolish its ability to bind to TRAF2 and to signal to NF‐κB. TRAF2, but not TRAF3, mediates the association of vFLIP with the IκB kinase complex. These data indicate that vFLIP uses TRAF2 and TRAF3 for signalling to NF‐κB, which is crucial for KSHV‐associated lymphomagenesis.
It and the Video Game Industry: Tensions and Mutual Shaping
Authors: Allen Jonathan P , Kim Jeffrey
Published: November 2005

This paper examines the influence of information technology (IT) on a distinct but closely related industry, the video game industry. We conceptualize the effects of IT as a process of translating three related dimensions of a technological frame - technology performance, industry practices, and use vision - from one industry to another. Through historical examples, we argue that the impact of IT on the video game industry is shaped and limited by this translation process, particularly when tensions between the two industries lead to the development of new complementary or replacement technologies, practices, or visions. Although heavily dependent on IT, the video game industry has had to ignore, postpone, or substantially modify important IT software tools, processors, storage media, graphics, and networking technologies because of these industry contradictions.
Redefining Access: Uses and Roles of Information and Communication Technologies in the US Residential Real Estate Industry from 1995 to 2005
Authors: Sawyer Steve , Wigand Rolf T , Crowston Kevin
Published: November 2005

We discuss three industry-level changes in the US residential real estate industry due, in part, to the take up and uses of information and communication technologies (ICT): (1) changes in the processes of transacting residential real estate, (2) changing roles for information, and (3) changing nature of intermediation, with the real estate transaction as more complex than the seller-agent-buyer simplification would suggest. We speculate that these changes are currently indeterminate due to ongoing confusion among the impacts of first and second-level effects, the roles of ICT in redefining access to data, and the importance of localized, social structures of real estate markets. To develop these findings, we take an institutional perspective and draw on multiple data collection methods. This provides us a means to highlight the value of an institutional perspective for studying industrial-level change.
Collaboration and the ‘3DayCar’: A Study of Automotive ICT Adoption
Authors: Howard Mickey
Published: November 2005

The 3DayCar programme reveals the principle source of delay during the order fulfilment process in the automotive industry as information processing not manufacturing. This suggests that information and communication technologies (ICT) are crucial in re-shaping industry structure towards customer responsiveness and building to order. This paper reports on the findings of a longitudinal study during a critical period for the industry where firms adopting web-enabled ICT seek to increase inter-organizational collaboration and gain competitive advantage over other supply chains. In all, 75 interviews across 28 firms examine the adoption of business-to-business (B2B) e-procurement and supply systems by vehicle manufacturers (VMs) and suppliers. Forms of organization are represented as a map of industry structure showing supply relationships and firm affiliation to B2B applications. VMs have tended to adopt a short-term price-driven approach using e-hubs and webEDI (electronic data interchange) in their attempts to control cost. Suppliers are concerned over an apparent disregard for firm autonomy, particularly those who have launched ICT projects of their own. Recommendations for the future are considered in light of what such large-scale efforts imply for design, deployment, and uses of ICT in industry settings.
Exploring Interorganizational Systems at the Industry Level of Analysis: Evidence from the US Home Mortgage Industry
Authors: Steinfield Charles W , Markus M Lynne , Wigand Rolf T
Published: November 2005

Interorganizational Systems (IOS) can have influences that extend beyond the organizations that implement them. Much can be learned at the industry-level of analysis that might not be revealed in studies conducted at the organizational level of analysis. This article summarizes a case study of one industry - the US home mortgage industry - in order to illustrate three types of industry-level phenomena that surface when examining use of interorganizational IT-driven coordination systems: collective actions among industry participants, performance effects, and structural effects. Our discussion of case results distinguishes between industry outcomes that are the net result of the accumulation of organizational actions vs. outcomes where industry-level consequences are qualitatively different from what is observed at the organizational level.
Theoretical study of Pt–Ng and Ng–Pt–Ng (Ng=Ar,Kr,Xe)
Authors: Ono Yuriko , Taketsugu Tetsuya , Noro Takeshi
Published: November 2005

We have investigated the binding of noble-gas (Ng) atoms (Ng=Ar,Kr,Xe) with Pt atom by the ab initio coupled-cluster CCSD(T) method, taking into account the relativistic effects. It is shown that two Ng atoms can bind with Pt atom in linear geometry in the singlet lowest state where the second Ng atom attaches to Pt with the larger binding energy than the first Ng atom. The binding energy is evaluated as 8.2, 17.9, and 33.4kcal∕mol for Ar–Pt–Ar, Kr–Pt–Kr, and Xe–Pt–Xe, respectively, relative to the triplet ground state of the dissociation limit Pt (D3)+2Ng. The present results indicate that these Ng–Pt–Ng compounds are possible new gas-phase or matrix species.
Stochastic dissociation of diatomic molecules
Authors: Kenfack Anatole , Rost Jan M.
Published: November 2005

The fragmentation of diatomic molecules under a stochastic force is investigated both classically and quantum mechanically, focusing on their dissociation probabilities. It is found that the quantum system is more robust than the classical one in the limit of a large number of kicks. The opposite behavior emerges for a small number of kicks. Quantum and classical dissociation probabilities do not coincide for any parameter combinations of the force. This can be attributed to a scaling property in the classical system which is broken quantum mechanically.
PbS nanocrystal synthesis in Pb-containing silicate glasses
Authors: Espiau de Lamaëstre R. , Bernas H.
Published: November 2005

We describe a synthesis of PbS nanocrystals in glasses, involving 150keV sulfur implantation into Pb-containing silicate glasses at peak concentrations up to 3.6at.% and postannealing around the glass transition temperature (500–600°C). The PbS nanocrystals, whose growth is evidenced by transmission electron microscopy, display intense photoluminescence (PL) in the 1–1.5μm wavelength range. Besides bypassing the sulfur retention problem occurring in traditional glass fusion techniques, our method improves control over nucleation and growth. The latter is demonstrated by the impact on the PbS nanocrystal PL properties of progressively replacing CaO by ZnO in a S-implanted Pb glass.
Lattice dynamics of ultrasmall silicon nanostructures
Authors: Hepplestone S. P. , Srivastava G. P.
Published: November 2005

A systematic study of the lattice dynamics of ultrasmall silicon nanostructures (nanoslabs, nanowires, and nanodots) is presented from the application of an adiabatic bond charge model. Characteristic features and trends unique to these structures are examined thoroughly. The smallest nanostructures are found to be characterized by the novel feature of gaps in the density of phonon states. Such gaps rapidly vanish with decreasing level of confinement of states as the size of the nanostructures increases. The results obtained for the highest confined mode for the three types of nanostructures have been fitted to analytic expressions following an extended Jusserand-type formulation. An expression has also been obtained for the size variation of the lowest nonzero zone-center mode. These expressions help explain and lend support to recently reported Raman scattering measurements. The present theoretical predictions for the variation of these modes will prove useful in accurate experimental determination of the confining size of the nanostructures.
Capillary force with a concave probe-tip for micromanipulation
Authors: Saito Shigeki , Motokado Tomoyuki , Obata Kenichi J. , Takahashi Kunio
Published: November 2005

This letter describes the measurement of capillary force with a concave probe-tip for micromanipulation. Using an electric balance, we measure the capillary force for a given gap distance between a spherical object and a concave surface coaxially fabricated on a cylinder. We used three different materials (glass, stainless steel, and polytetrafluoroethylene) to check the influence of contact angles. The results are in good agreement with the theoretical prediction expressed in the normalized form; these indicate that a concave tip can generate a much larger capillary force than a flat one, provided the tip is designed to fit the convex surface of the object; moreover the results clarify that the more wettable a material is, the greater capillary force it can generate. This suggests micromanipulation by capillary force should be more practical by using probes with concave tips specifically designed for the object.
Characterizing Location Preferences in an Exurban Population: Implications for Agent-Based Modeling
Authors: Fernandez Luis E , Brown Daniel G , Marans Robert W , Nassauer Joan I
Published: November 2005

Powerful computational tools are becoming available to represent the behavior of complex systems. Agent-based modeling, in particular, facilitates an examination of the system-level outcomes of the heterogeneous actions of a set of heterogeneous agents: for example, patterns of land-use and land-cover change, such as urban sprawl as a result of residential location decisions. These new tools create new demands for data, and empirical studies of the selection behavior of residents. Using resident responses from the 2001 Detroit Area Study survey, we compared two alternative approaches to characterizing the heterogeneous preferences of agents; both based on a factor analysis of resident responses to questions about their reasons for moving to their current location. We used cluster analysis to identify how many and what types of residents there are, grouped by similar preferences. We also evaluated the relationships between socioeconomic and demographic characteristics and location preferences using regression trees, and evaluated the fit of the relationship to determine the degree to which socioeconomic characteristics predict preferences. The results showed that the preferences of resident exurbans of single-family homes in the Detroit metropolitan area were heterogeneous and that distinct preference groups do exist in resident populations, but are not well characterized on the basis of simple socioeconomic and demographic variables. We conclude that, given the heterogeneous nature of preferences and a relatively limited number of preference groupings observed in the survey respondents, agent-based models simulating resident behavior should reflect this diversity in the population and incorporate distinct agent classes of empirically derived preference distributions.
Spatial Fluctuations as Signatures of Self-Organization: A Complex Systems Approach to Landscape Dynamics in Rondônia, Brazil
Authors: Crawford Thomas W
Published: November 2005

Self-organization is a prominent theme of complexity studies that has been applied in studies of urban evolution and land-cover change. Little work has investigated the potential of self-organization to describe and explain landscape dynamics in frontier settings. The principal aims of this paper are: (a) to present a general theoretical framework of landscape dynamics for a frontier setting in Rondônia, Brazil based on a specific theory of self-organization known as self-organized criticality (SOC), (b) to describe the settlement pattern of a recently settled landscape by focusing on spatial fluctuations of landscape metrics as signatures, and (c) to discuss how plausible mechanisms with clear links to SOC may be considered by investigators of landscape evolution. A general SOC framework is situated within prevailing frameworks that feature proximate and distant drivers of land-cover change. Fourier techniques are used to assess spatial fluctuations of pattern metrics in multiple directions as landscape signatures. Periodicity and 1/ f signatures consistent with SOC are simultaneously present dependent on directional orientation. Settings where SOC may serve as an important yet ultimately partial framework for pattern-oriented description and process-oriented explanation are discussed.
Current and Future Patterns of Land-Use Change in the Coastal Zone of New Jersey
Authors: Conway Tenley M
Published: November 2005

Recent urban development along the US coasts has negatively impacted the local environment, and these impacts will only increase thanks to rapid regional population growth. Empirical spatially disaggregate land-use models provide a way to explore future conditions and environmental impacts before irreversible changes occur. An assumption of many models is that access to urban-employment centers is the major factor locating urban uses within a region, the opposite of the pattern seen in most natural amenity rich areas. As a result, it is unclear whether models focusing on center accessibility can be used to predict future land-use patterns in urbanizing coastal regions. In this paper the relationship between accessibility and the location of urban development was examined for coastal New Jersey, USA. Two questions were addressed through the analysis: (1) Is accessibility to urban or employment centers correlated with the location of urban conversions? (2) If accessibility is correlated with the location of urban conversion, does the inclusion of such variables into a land-use-change model improve the ability of the model to locate future urban development? Results from the analysis indicate that traditional accessibility relationships can be used to explain the location of urban conversions in New Jersey's coastal region, but inclusion of accessibility and other locating factors does not necessarily improve the predictive ability of a model. The accessibility relationship is contrary to findings in many other high-amenity areas, because, in part, of the importance of access to the region's transportation network.
Landscape Grammar 1: Spatial Grammar Theory and Landscape Planning
Authors: Mayall Kevin , Hall G Brent
Published: November 2005

This paper presents the concept of a spatial landscape grammar. The concept formally draws parallels between the structures of linguistics and the character of real-world landscapes. Landscape grammar can be used to define a landscape's character by using a vocabulary of landscape object types and spatial syntax rules, and these can be used to generate landscape scenes rendered in two or three dimensions through the use of a generative and interpretive production system and modern computing technology. The spatial counterparts of the linguistic concepts of vocabulary and grammar rules are formalized and the basis of the landscape production system is presented. The paper concludes with a short discussion of actual landscape scene generation as a prelude to a companion paper that describes a full implementation of the grammar and interpreter for a residential neighbourhood in Bermuda.
Dynamic Spatial Simulation Modeling of the Population — Environment Matrix in the Ecuadorian Amazon
Authors: Messina Joseph P , Walsh Stephen J
Published: November 2005

This research uses multithematic and spatially explicit data combined from a longitudinal socioeconomic and demographic survey conducted in 1990 and 1999, GIS coverages of resource endowments and geographic accessibility, and a classified Landsat Thematic Mapper (TM) satellite time series. The goal was to combine such data with expert knowledge, a set of analytic results, and dynamic modeling approaches to describe, explain, and explore the causes and consequences of land use and cover change (LUCC) in the northern Oriente region of the Ecuadorian Amazon. First, a cellular automaton (CA) model representing LUCC was developed using a time series of remotely sensed Landsat TM images for a 90 000-ha intensive study area within the region and calibrated using alternative images from the time series. The classified images were linked to spatially referenced biophysical and socioeconomic coverages used as input data, and then combined with ‘rules’ derived from empirical analyses. Second, the CA model was used in dynamic simulations to explore LUCC as both causes and consequences of (a) road development, (b) agricultural extensification and land abandonment, (c) major shifts in world markets and crop prices, and (d) urban expansion of the central city within the region. Finally, complexity theory was explored within the spatial and temporal dynamics associated with population – environment interactions, particularly, deforestation, urbanization, and subsistence and commercial cultivation of agricultural crops on lands made accessible by petroleum-company-built roads and the corresponding in-migration of spontaneous colonists beginning in the late 1960s. This research contributes to the study of population – environment interactions in a frontier environment, and examines how dynamic and complex systems can be modeled using CA-based spatial simulations.
Modeling Enrollment in the Conservation Reserve Program by Using Agents within Spatial Decision Support Systems: An Example from Southern Illinois
Authors: Sengupta Raja , Lant Christopher , Kraft Steven , Beaulieu Jeffrey , Peterson William , Loftus Timothy
Published: November 2005

Existing models of agricultural decisionmaking based on economic optimization often fall short of capturing the complex dynamics of land-use choices at both individual parcel and watershed-level scales. The complexity arises from an interplay of several factors, as explained by Herbert Simon's model of bounded rationality, the theory of diffusion of innovations through spatial contagion, the role of personal environmental values and local culture, and simple historical momentum. This complexity can be captured using ‘artificial life agents’ that model land-use choice for individual parcels by considering characteristics and personal beliefs of the owner or operator, physical traits of the land, and information obtained via social networks. Agents are therefore able to consider holistically a large number of factors affecting land-use choice. The creation of agent-based models of human behavior described herein is based upon empirical data on the acceptance of Conservation Reserve Program for the Cache River watershed of southern Illinois (USA). These models are interfaced with a geographic information system to produce a spatial decision support system capable of anticipating the effects of policies that affect land-use decisionmaking on a real landscape and their economic performance.
Evidence for Holistic Processing of Faces Viewed as Photographic Negatives
Authors: Hole Graham J , George Patricia A , Dunsmore Victoria
Published: November 2005

Inversion and photographic negation both impair face recognition. Inversion seems to disrupt processing of the spatial relationship between facial features (‘relational’ processing) which normally occurs with upright faces and which facilitates their recognition. It remains unclear why negation affects recognition. To find out if negation impairs relational processing, we investigated whether negative faces are subject to the ‘chimeric-face effect’. Recognition of the top half of a composite face (constructed from top and bottom halves of different faces) is difficult when the face is upright, but not when it is inverted. To perform this task successfully, the bottom half of the face has to be disregarded, but the relational processing which normally occurs with upright faces makes this difficult. Inversion reduces relational processing and thus facilitates performance on this particular task.

In our experiments, subjects saw pairs of chimeric faces and had to decide whether or not the top halves were identical. On half the trials the two chimeras had identical tops; on the remaining trials the top halves were different. (The bottom halves were always different.) All permutations of orientation (upright or inverted) and luminance (normal or negative) were used. In experiment 1, each pair of ‘identical’ top halves were the same in all respects. Experiment 2 used differently oriented views of the same person, to preclude matches being based on incidental features of the images rather than the faces displayed within them. In both experiments, similar chimeric-face effects were obtained with both positive and negative faces, implying that negative faces evoke some form of relational processing. It is argued that there may be more than one kind of relational processing involved in face recognition: the ‘chimeric-face effect’ may reflect an initial ‘holistic’ processing which binds facial features into a ‘Gestalt’, rather than being a demonstration of the configurational processing involved in individual recognition.
Single Units and Sensation: A Retrospect
Authors: Lee Barry B
Published: November 2005

The single-neuron doctrine is reexamined, and the search for causal links between single units and sensation reviewed. Although several decades of single-unit recording have been very successful in elucidating physiological mechanisms, linking signals from a single cell and perception has progressed at a slower rate. Nevertheless, analysing the activity of single neurons has achieved significant gains and remains the most promising level for elucidation of processing algorithms in the visual system. At the subcortical level, the conclusion that signals from just a single cell can carry enough information for some kinds of performance remains (almost) valid. Under carefully controlled conditions, just a few impulses in a few retinal ganglion cells are an adequate signal for the cortex to initiate a behavioural response. Elucidating cortical codes has been more difficult, and evidence exists suggesting the sharing of responsibility for a task among cell assemblies; how large these assemblies are, and how to test for them neurophysiologically, remains a challenge.
An Airplane Illusion: Apparent Velocity Determined by Apparent Distance
Authors: Hershenson Maurice , Samuels Steven M
Published: November 2005

When a small drone plane appears to be a normal-sized airplane, it appears to be very far away and moving too fast. This is the airplane illusion. In the illusory situation, familiar size determines the apparent size and distance of the plane. It sets the depth for the frontal-plane component of the perceived motion and the relative depth difference for the motion-in-depth component. Because these perceived distances are very large, the perceived velocities are very large in the respective directions. Cognition can override familiarity and produce a veridical perception of the drone.
Paradigm Shifts: New Techniques to Answer New Questions
Authors: Olzak Lynn A , Wickens Thomas D
Published: November 2005

The advent of a multiple-channels approach to spatial vision 20 years ago raised important questions that were difficult to approach empirically, given the technology and analytic tools of the time. These questions concerned the interaction or combination of different components of a stimulus—questions that have recently resurfaced in more complex form. Classical psychophysical methods for assessing whether two stimulus aspects are coded independently (eg masking, adaptation, and cue-summation) provide only limited information about the nature of whatever interactions are discovered. In both older work in detection and recent work in complex pattern discrimination, we have used a double-judgment paradigm in which the observer rates two aspects of a stimulus simultaneously. The paradigm provides a rich source of information about the codes underlying each psychophysical decision and which are unique in permitting us to psychophysically investigate effects resulting from neural noise in the system. Our analyses draw on theories of dimensional interaction in signal detection theory and in information theory, and on methods from several branches of statistics, including categorical data analysis and structural equation modeling. We review the theoretical, technological, methodological, and personal influences that led us to develop this approach.
Revisiting the Global-Dominance Phenomenon outside the Focus of Attention
Authors: Paquet Lise
Published: November 2005

Previous research has demonstrated global dominance for attended and unattended stimuli. In this paper, this phenomenon is shown to be restricted to small compound stimuli. As a first step, local dominance was obtained with large (8 deg in height) attended stimuli when a single stimulus was displayed. Next, dominance in attended and unattended stimuli was investigated by displaying two large compound stimuli, one surrounded by a square (attended compound stimulus), the other one enclosed in a circle (unattended compound stimulus). The way attention was directed to the attended stimulus was varied. No dominance was observed when subjects were instructed to process the stimulus appearing in the square (experiment 2). However, when a rapid-onset cue pre-directed attention to the attended stimulus, local dominance emerged for attended, but not for unattended stimuli (experiment 3). This latter result was obtained whether or not subjects were more experienced at local than global processing (experiment 4). The implications of the results for the locus of processing dominance are discussed.
Lightness Induction Revisited
Authors: Logvinenko Alexander D
Published: November 2005

Lightness induction is the classical visual phenomenon whereby the lightness of an object is shown to depend on its immediate surround. Despite the long history of its study, lightness induction has not yet been coherently and satisfactorily explained in all its variety. The two main theories that compete to explain it descend (i) from H von Helmholtz, who believed that lightness induction originates from some central mechanisms that take into account the whole viewing situation, with particular stress upon the apparent illumination of the object; and (ii) E Hering who argued in favour of more peripheral sensory mechanisms based on local luminance contrast. The balance between these theories has recently been shifted towards Helmholtz's position by E H Adelson who has provided additional evidence that lightness induction depends on perceptual interpretation and, particularly, on apparent transparency.

I challenge Adelson's conclusions by introducing modified versions of his tile pattern that use luminance gradients. In the first of these new demonstrations there is a strong lightness induction even though no apparent transparency is experienced. In the second there is a clear impression of transparent strips, yet no lightness induction is present. And the third shows that breaking up the Adelson tile pattern, while it affects neither the impression of transparency nor the type of grey-level junctions, makes the lightness-induction effect vanish. This implies that Adelson's illusion can be accounted for by neither local contrast, nor the apparent transparency, nor the type of grey-level junctions. Presented here is an alternative look at lightness induction as a phenomenon of the pictorial (as contrasted to natural) vision, which rests on the lightness – shadow invariance, much as Gregory's ‘inappropriate constancy scaling’ theory of geometrical illusions rests on the apparent size – distance invariance.
Progress and Paradigm Shifts in Spatial Vision over the 20 Years of Ecvp
Authors: Levi Dennis M
Published: November 2005

In the beginning there was light, and form, and visual mechanisms. This paper traces developments in research on spatial vision over the 20 years of ECVP, with particular emphasis on (1) hyperacuity, (2) peripheral vision, (3) amblyopia and development, and (4) learning and plasticity.
The Myth of Upright Vision. A Psychophysical and Functional Imaging Study of Adaptation to Inverting Spectacles
Authors: Linden David E J , Kallenbach Ulrich , Heinecke Armin , Singer Wolf , Goebel Rainer
Published: November 2005

The adaptation to inverting prisms and mirror spectacles was studied in four subjects over periods of six to ten days. Subjects showed rapid adaptation of visuomotor functions, but did not report return of upright vision. The persistence of the transformed visual image was confirmed by the subjects' perception of shape from shading. No alteration of the retinotopy of early visual cortical areas was seen in the functional magnetic resonance images. These results are discussed in the context of previous claims of upright vision with inverting prisms and mirror spectacles.
Seeing Big Things: Overestimation of Heights is Greater for Real Objects Than for Objects in Pictures
Authors: Yang Tyrone L , Dixon Melissa W , Proffitt Dennis R
Published: November 2005

In six experiments we demonstrate that the vertical–horizontal illusion that is evoked when viewing photographs and line drawings is relatively small, whereas the magnitude of this illusion when large objects are viewed is at least twice as great. Furthermore, we show that the illusion is due more to vertical overestimation than horizontal underestimation. The lack of a difference in vertical overestimation between pictures and line drawings suggests that vertical overestimation in pictures depends solely on the perceived physical size of the projection on the picture surface, rather than on what is apparent about an object's represented size. The vertical–horizontal illusion is influenced by perceived physical size. It is greater when viewing large objects than small pictures of these same objects, even when visual angles are equated.
The Perception of Tactile Distance: Influences of Body Site, Space, and Time
Authors: Cholewiak Roger W
Published: November 2005

Vibrotactile prostheses for deaf or blind persons have been applied to any number of different locations on the body, including the finger, wrist, forearm, abdomen, back, and nape of the neck. The discriminability of patterns presented by such devices can be affected by the acuity of the site of application and the resolution of the display. In addition, the mutual influences among stimuli close together in both space and time can affect percepts within a broad range of parameters. For example, consideration must be given to a variety of tactile illusions often associated with the spatial separations and the range of temporal intervals typically used in cutaneous communication displays. Experiments are reported in which magnitude estimates and cross-modality matches of perceived extent produced by pairs of vibrotactile taps presented to separate loci were obtained on three different body sites. Perceived distance was directly related both to the timing between the taps and to their physical separation. The findings show a consistent relationship to cortical magnification across body sites.
The Historical Roots of the Theories of Local Signs and Labelled Lines
Authors: Rose David
Published: November 2005

The theories of labelled lines and local signs are commonly invoked to explain numerous perceptual phenomena. These theories postulate that perceptual systems use information about which nerve cells or which information channels are activated by the stimulus. The origins of this idea in nineteenth century German psychophysics are traced. From Descartes's idea of a dualistic mind, Kant's idea of a mental ability to conceive space, Da Vinci's ideas of pictorial ‘signs’, and Müller's idea of ‘specific nerve energies’ to explain perceptual qualities, Steinbuch, Lotze, and others derived the conclusion that neural-level signs exist that signal stimulus location to the mind. Helmholtz, Hering, and others soon suggested variations on this basic idea. By the time of James the theory had changed yet again. It was revived elsewhere in the 1920s and again in the 1970s, although used implicitly by many workers in between and since. Against a modern metaphysical background, however, a distinction between labels (hardware) and signs (symbols) is the minimum step needed towards an appropriate and comprehensive explanation of perceptual behaviour and experience.
Identification of Gender in Domestic-Cat Faces with and without Training: Perceptual Learning of a Natural Categorization Task
Authors: Quinn Paul C , Palmer Vanessa , Slater Alan M
Published: November 2005

Three experiments were conducted to determine whether human observers could identify the gender of 40 domestic cats (20 female, 20 male) depicted in individual color photographs. In experiment la, observers performed at chance for photographs depicting whole cats, cat heads (bodies occluded), and cat bodies (heads occluded). Experiment lb showed that chance performance was also obtained when the photographs were full-face close-ups of the cats. Experiment 2a revealed that even with gender-identification training on 30 (15 female, 15 male) of the 40 face close-ups, observers were unable to generalize their training to reliably identify the gender of the 10 remaining test faces (5 female, 5 male). However, experiment 2b showed that gender-identification training with the 14 most accurately identified faces from experiment 1b (7 female, 7 male) was successful in raising gender identification of the 10 test faces above chance. Experiments 3a and 3b extended this facilitative effect of gender-identification training to a population of animal-care workers. The findings indicate that, with appropriate training, human observers can identify the gender of cat faces at an above-chance level. A perceptual category learning account emphasizing the on-line formation of differentiated male versus female prototypes during training is offered as an explanation of the findings.
What Object Attributes Determine Canonical Views?
Authors: Blanz Volker , Tarr Michael J , Bülthoff Heinrich H
Published: November 2005

We investigated preferred or canonical views for familiar and three-dimensional nonsense objects using computer-graphics psychophysics. We assessed the canonical views for objects by allowing participants to actively rotate realistically shaded three-dimensional models in realtime. Objects were viewed on a Silicon Graphics workstation and manipulated in virtual space with a three-degree-of-freedom input device. In the first experiment, participants adjusted each object to the viewpoint from which they would take a photograph if they planned to use the object to illustrate a brochure. In the second experiment, participants mentally imaged each object on the basis of the name and then adjusted the object to the viewpoint from which they imagined it. In both experiments, there was a large degree of consistency across participants in terms of the preferred view for a given object. Our results provide new insights on the geometrical, experiential, and functional attributes that determine canonical views under ecological conditions.
Viewpoint-Dependent Recognition of Familiar Faces
Authors: Troje Nikolaus F , Kersten Daniel
Published: November 2005

The question whether object representations in the human brain are object-centered or viewer-centered has motivated a variety of experiments with divergent results. A key issue concerns the visual recognition of objects seen from novel views. If recognition performance depends on whether a particular view has been seen before, it can be interpreted as evidence for a viewer-centered representation. Earlier experiments used unfamiliar objects to provide the experimenter with complete control over the observer's previous experience with the object. In this study, we tested whether human recognition shows viewpoint dependence for the highly familiar faces of well-known colleagues and for the observer's own face. We found that observers are poorer at recognizing their own profile, whereas there is no difference in response time between frontal and profile views of other faces. This result shows that extensive experience and familiarity with one's own face is not sufficient to produce viewpoint invariance. Our result provides strong evidence for viewer-centered representations in human visual recognition even for highly familiar objects.