bluuebunny/crossref_metadata_2025 huggingface dataset:
Gestalt isomorphism and the primacy of subjective conscious experience: A Gestalt Bubble model
Authors: Lehar Steven
Published: April 2004

A serious crisis is identified in theories of neurocomputation, marked by a persistent disparity between the phenomenological or experiential account of visual perception and the neurophysiological level of description of the visual system. In particular, conventional concepts of neural processing offer no explanation for the holistic global aspects of perception identified by Gestalt theory. The problem is paradigmatic and can be traced to contemporary concepts of the functional role of the neural cell, known as the Neuron Doctrine. In the absence of an alternative neurophysiologically plausible model, I propose a perceptual modeling approach, to model the percept as experienced subjectively, rather than modeling the objective neurophysiological state of the visual system that supposedly subserves that experience. A Gestalt Bubble model is presented to demonstrate how the elusive Gestalt principles of emergence, reification, and invariance can be expressed in a quantitative model of the subjective experience of visual consciousness. That model in turn reveals a unique computational strategy underlying visual processing, which is unlike any algorithm devised by man, and certainly unlike the atomistic feed-forward model of neurocomputation offered by the Neuron Doctrine paradigm. The perceptual modeling approach reveals the primary function of perception as that of generating a fully spatial virtual-reality replica of the external world in an internal representation. The common objections to this “picture-in-the-head” concept of perceptual representation are shown to be ill founded.
The E-Z Reader model of eye-movement control in reading: Comparisons to other models
Authors: Reichle Erik D. , Rayner Keith , Pollatsek Alexander
Published: April 2004

The E-Z Reader model (Reichle et al. 1998; 1999) provides a theoretical framework for understanding how word identification, visual processing, attention, and oculomotor control jointly determine when and where the eyes move during reading. In this article, we first review what is known about eye movements during reading. Then we provide an updated version of the model (E-Z Reader 7) and describe how it accounts for basic findings about eye movement control in reading. We then review several alternative models of eye movement control in reading, discussing both their core assumptions and their theoretical scope. On the basis of this discussion, we conclude that E-Z Reader provides the most comprehensive account of eye movement control during reading. Finally, we provide a brief overview of what is known about the neural systems that support the various components of reading, and suggest how the cognitive constructs of our model might map onto this neural architecture.
Freud's dual process theory and the place of the a-rational
Authors: Brakel Linda A. W. , Shevrin Howard
Published: April 2004

In this commentary on Stanovich & West (S&W) we call attention to two points: (1) Freud's original dual process theory, which antedates others by some seventy-five years, deserves inclusion in any consideration of dual process theories. His concepts of primary and secondary processes (Systems 1 and 2, respectively) anticipate significant aspects of current dual process theories and provide an explanation for many of their characteristics. (2) System 1 is neither rational nor irrational, but instead a-rational. Nevertheless, both the a-rational System 1 and the rational System 2 can each have different roles in enhancing evolutionary fitness. Lastly, System 1 operations are incorrectly deemed “rational” whenever they increase evolutionary fitness.
Phenomenology is art, not psychological or neural science
Authors: Booth David A.
Published: April 2004

It is tough to relate visual perception or other achievements to physiological processing in the central nervous system. The diagrammatic, algebraic, and verbal pictures of how sights seem to Lehar do not advance understanding of how we manage to see what is in the world. There are well-known conceptual reasons why no such purely introspective approach can be productive.
Double, double, toil and trouble – fire burn, and theory bubble!
Authors: Dresp Birgitta
Published: April 2004

Lehar's Gestalt Bubble model introduces a computational approach to holistic aspects of three-dimensional scene perception. The model as such has merit because it manages to translate certain Gestalt principles of perceptual organization into formal codes or algorithms. The mistake made in this target article is to present the model within the theoretical framework of the question of consciousness. As a scientific approach to the problem of consciousness, the Gestalt Bubble fails for several reasons. This commentary addresses three of these: (1) the terminology surrounding the concept of consciousness is not rigorously defined; (2) it is not made evident that three-dimensional scene perception requires consciousness at all; and (3) it is not clearly explained by which mechanism(s) the “picture-in-the-head,” supposedly represented in the brain, would be made available to different levels of awareness or consciousness.
Individual differences transcend the rationality debate
Authors: Newton Elizabeth J. , Roberts Maxwell J.
Published: April 2004

Individual differences are indeed an important aid to our understanding of human cognition, but the importance of the rationality debate is open to question. An understanding of the process involved, and how and why differences occur, is fundamental to our understanding of human reasoning and decision making.
Please stop using word frequency data that are likely to be word length effects in disguise
Authors: Brysbaert Marc , Drieghe Denis
Published: April 2004

Reichle et al. claim to successfully simulate a frequency effect of 60% on skipping rate in human data, whereas the original article reports an effect of only 4%. We suspect that the deviation is attributable to the length of the words in the different conditions, which implies that E-Z Reader is wrong in its conception of eye guidance between words.
The rationality debate as a progressive research program
Authors: Stanovich Keith E. , West Richard F.
Published: April 2004

We did not, as Brakel & Shevrin imply, intend to classify either System 1 or System 2 as rational or irrational. Instrumental rationality is assessed at the organismic level, not at the subpersonal level. Thus, neither System 1 nor System 2 are themselves inherently rational or irrational. Also, that genetic fitness and instrumental rationality are not to be equated was a major theme in our target article. We disagree with Bringsjord & Yang's point that the tasks used in the heuristics and biases literature are easy. Bringsjord & Yang too readily conflate the ability to utilize a principle of rational choice with the disposition to do so. Thus, they undervalue tasks in the cognitive science literature that compellingly reveal difficulties with the latter. We agree with Newton & Roberts that models at the algorithmic level of analysis are crucial, but we disagree with their implication that attention to issues of rationality at the intentional level of analysis impedes work at the algorithmic level of analysis.
Empirical constraints for perceptual modeling
Authors: Fox Charles R.
Published: April 2004

This new heuristic model of perceptual analysis raises interesting issues but in the end falls short. Its arguments are more in the Cartesian than Gestalt tradition. Much of the argument is based on setting up theoretical straw men and ignores well known perceptual and brain science. Arguments are reviewed in light of known physiology and traditional Gestalt theory.
Linking visual cortex to visual perception: An alternative to the Gestalt Bubble
Authors: Grossberg Stephen
Published: April 2004

Lehar's lively discussion builds on a critique of neural models of vision that is incorrect in its general and specific claims. He espouses a Gestalt perceptual approach rather than one consistent with the “objective neurophysiological state of the visual system” (target article, Abstract). Contemporary vision models realize his perceptual goals and also quantitatively explain neurophysiological and anatomical data.
Backdrop, flat, and prop: The stage for active perceptual inquiry
Authors: Hochberg Julian
Published: April 2004

Lehar's revival of phenomenology and his all-encompassing Gestalt Bubble model are ambitious and stimulating. I offer an illustrated caution about phenomenology, a more fractured alternative to his Bubble model, and two lines of phenomena that may disqualify his isomorphism. I think a perceptual-inquiry model can contend.
Throwing the baby out with the bathwater: Problems in modeling aggregated eye-movement data
Authors: Feng Gary
Published: April 2004

Parameters in E-Z Reader models are estimated on the basis of a simple data set consisting of 30 means. Because of heavy aggregation, the data have a severe problem of multicolinearity and are unable to adequately constrain parameter values. This could give the model more power than the empirical data warrant. Future models should exploit the richness of eye movement data and avoid excessive aggregation.
Does perception replicate the external world?
Authors: Hoffman Donald D.
Published: April 2004

Vision scientists standardly assume that the goal of vision is to recover properties of the external world. Lehar's “miniature, virtual-reality replica of the external world inside our head” (target article, sect. 10) is an example of this assumption. I propose instead, on evolutionary grounds, that the goal of vision is simply to provide a useful user interface to the external world.
Dimensionality and explanatory power of reading models
Authors: Hanes Douglas , McCollum Gin
Published: April 2004

The authors' review of alternative models for reading is of great value in identifying issues and progress in the field. More emphasis should be given to distinguishing between models that offer an explanation for behavior and those that merely simulate experimental data. An analysis of a model's discrete structure can allow for comparisons of models based upon their inherent dimensionality and explanatory power.
Isomorphism and representationalism
Authors: Luccio Riccardo
Published: April 2004

Lehar tries to build a computational theory that succeeds in offering the same computational model for both phenomenal experience and visual processing. However, the vision that Lehar has about isomorphism in Gestalttheorie as representational, is not adequate. The main limit of Lehar's model derives from this misunderstanding of the relation between phenomenal and physiological levels.
Future challenges to E-Z Reader: Effects of OVP and morphology on processing long and short compounds
Authors: Hyönä Jukka , Bertram Raymond
Published: April 2004

We argue that although E-Z Reader does a good job in simulating many basic facts related to readers' eye movements, two phenomena appear to pose a challenge to the model. The first has to do with word length mediating the way compound words are identified; the second concerns the effects of initial fixation position in a word on eye behavior.
Bursting the bubble: Do we need true Gestalt isomorphism?
Authors: McLoughlin Niall P.
Published: April 2004

Lehar proposes an interesting theory of visual perception based on an explicit three-dimensional representation of the world existing in the observer's head. However, if we apply Occam's razor to this proposal, it is possible to contemplate far simpler representations of the world. Such representations have the advantage that they agree with findings in modern neuroscience.
On keeping word order straight
Authors: Kennedy Alan
Published: April 2004

E-Z Reader is a highly successful model of eye-movement control, employing the notion of a serial-sequential attentional spotlight switched from word to word. Evidence of parallel processing of words in text calls this notion into question. Modifications to the model to accommodate this evidence are possible but will not address the fundamental objection that reading should not be seen as “surrogate listening.”
Relations between three-dimensional, volumetric experiences, and neural processes: Limitations of materialism
Authors: Randrup Axel
Published: April 2004

Certain features of perception – the quale red, for example, and other qualia – must be regarded as additions to the materialist neurophysiological picture of perception. The perception of three-dimensional volumetric objects can also be seen as qualitative additions to the neurophysiological processes in the brain, possibly without additions to the information content.
How tight is the link between lexical processing and saccade programs?
Authors: Kliegl Reinhold , Engbert Ralf
Published: April 2004

We question the assumption of serial attention shifts and the assumption that saccade programs are initiated or canceled only after stage one of word identification. Evidence: (1) Fixation durations prior to skipped words are not consistently higher compared to those prior to nonskipped words. (2) Attentional modulation of microsaccade rate might occur after early visual processing. Saccades are probably triggered by attentional selection.
Neurological models of size scaling
Authors: Ross Helen E.
Published: April 2004

Lehar argues that a simple Neuron Doctrine cannot explain perceptual phenomena such as size constancy but he fails to discuss existing, more complex neurological models. Size models that rely purely on scaling for distance are sparse, but several models are also concerned with other aspects of size perception such as geometrical illusions, relative size, adaptation, perceptual learning, and size discrimination.
Linguistically guided refixations
Authors: Pacht Jeremy
Published: April 2004

I discuss evidence for direct linguistic control of refixations and argue that the E-Z Reader model's account of refixations requires elaboration or revision.
Is the world in the brain, or the brain in the world?
Authors: Velmans Max
Published: April 2004

Lehar provides useful insights into spatially extended phenomenology that may have major consequences for neuroscience. However, Lehar's biological naturalism leads to counterintuitive conclusions, and he does not give an accurate account of preceding and competing work. This commentary compares Lehar's analysis with that of Velmans, which addresses similar issues but draws opposite conclusions. Lehar argues that the phenomenal world is in the brain and concludes that the physical skull is beyond the phenomenal world. Velmans argues that the brain is in the phenomenal world and concludes that the physical skull is where it seems to be.
Percepts are selected from nonconceptual sensory fields
Authors: Wright Edmond
Published: April 2004

Steven Lehar allows too much to his direct realist opponent in using the word “subjective” of the sensory field per se. The latter retains its nonconceptual, nonmental nature even when explored by perceptual judgement. He also needs to stress the evolutionary value of perceptual differences between person and person, a move that enables one to undermine the direct realist's superstitious certainty about the singular object.
E-Z Reader 7 provides a platform for explaining how low- and high-level linguistic processes influence eye movements
Authors: Raney Gary E.
Published: April 2004

E-Z Reader 7 is a processing model of eye-movement control. One constraint imposed on the model is that high-level cognitive processes do not influence eye movements unless normal reading processes are disturbed. I suggest that this constraint is unnecessary, and that the model provides a sensible architecture for explaining how both low- and high-level processes influence eye movements.
Eye-movement control in reading: Models and predictions
Authors: Reingold Eyal M.
Published: April 2004

It is argued here that a critical prediction of the E-Z Reader model is that experimental manipulations that disrupt early encoding of visual and orthographic features of the fixated word without affecting subsequent lexical processing should influence the processing difficulty of the fixated word without producing any processing effect on the next word. This prediction is explained and illustrated.
Neural plausibility and validation may not be so E-Z
Authors: Sereno Sara C. , O'Donnell Patrick J. , Sereno Anne B.
Published: April 2004

Although the E-Z Reader model accounts well for eye-tracking data, it will be judged by new predictions and consistency with evidence from brain imaging methodologies. The stage architecture proposed for lexical access seems somewhat arbitrary and calculated timings are conservatively slow. There are certain effects in the literature that seem incompatible with the model.
Reading and the split fovea
Authors: Shillcock Richard , McDonald Scott , Monaghan Padraic
Published: April 2004

We argue that models of reading should be based on anatomical reality, namely, the fact that both eyes are used in reading; and the observation that the human fovea is precisely vertically split, and projects each half of a fixated word to the contralateral hemisphere.
The effects of frequency and predictability on eye fixations in reading: An evaluation of the E-Z Reader model
Authors: Sparrow Laurent , Miellet Sébastien , Coello Yann
Published: April 2004

We tested whether the E-Z Reader model can be generalised to the French language. The simulation showed that the model can account for the frequency effect. The predictability effect is moreover accurate for word skipping, but not for fixation times. We think that this model is psychologically plausible for certain aspects of reading and we have used it to evaluate the performance of dyslexic readers.
Calibration of the Mg/Ca of Globorotalia truncatulinoides (R) for the reconstruction of marine temperature gradients
Authors: McKenna V. S. , Prell W. L.
Published: April 2004

Recent work has provided useful Mg/Ca to water temperature calibrations for shallow‐dwelling planktonic foraminifer species. Globorotalia truncatulinoides (right coiling (R)) is a deep‐dwelling species that can serve as a source of information about the temporal variability in the water characteristics of the thermocline. We present a temperature calibration for the Mg/Ca in the shell of G. truncatulinoides (R) and examine some of the practical issues associated with evaluating the usefulness of the technique. The Mg/Ca in the primary and the secondary calcite of individual G. truncatulinoides (R) correlates exponentially with water column temperatures, showing a change of ∼10% in the Mg/Ca per 1°C (R2 = 0.92). A limited comparison with plankton tow samples demonstrates that the average Mg/Ca temperature was offset +1°C from the average temperature calculated using the δ18O calibration of O'Neil et al. [1969], and the Mg/Ca temperatures have a range similar to the δ18O temperatures. Comparisons of the [Mg] in the core top samples to water depth of deposition indicates that dissolution does not alter the measured value of Mg in the primary calcite.
Storm‐driven mixing and potential impact on the Arctic Ocean
Authors: Yang Jiayan , Comiso Josefino , Walsh David , Krishfield Richard , Honjo Susumu
Published: April 2004

Observations of the ocean, atmosphere, and ice made by Ice‐Ocean Environmental Buoys indicate that mixing events reaching the depth of the halocline have occurred in various regions in the Arctic Ocean. Our analysis suggests that these mixing events were mechanically forced by intense storms moving across the buoy sites. In this study, we analyzed these mixing events in the context of storm developments that occurred in the Beaufort Sea and in the general area just north of Fram Strait, two areas with quite different hydrographic structures. The Beaufort Sea is strongly influenced by inflow of Pacific water through Bering Strait, while the area north of Fram Strait is directly affected by the inflow of warm and salty North Atlantic water. Our analyses of the basin‐wide evolution of the surface pressure and geostrophic wind fields indicate that the characteristics of the storms could be very different. The buoy‐observed mixing occurred only in the spring and winter seasons when the stratification was relatively weak. This indicates the importance of stratification, although the mixing itself was mechanically driven. We also analyze the distribution of storms, both the long‐term climatology and the patterns for each year in the past 2 decades. The frequency of storms is also shown to be correlated (but not strongly) to Arctic Oscillation indices. This study indicates that the formation of new ice that leads to brine rejection is unlikely the mechanism that results in the type of mixing that could overturn the halocline. On the other hand, synoptic‐scale storms can force mixing deep enough to the halocline and thermocline layer. Despite a very stable stratification associated with the Arctic halocline, the warm subsurface thermocline water is not always insulated from the mixed layer.
Tomoeye: A Matlab package for visualization of three‐dimensional tomographic models
Authors: Gorbatov A. , Limaye A. , Sambridge M.
Published: April 2004

The use of seismic imaging techniques is widespread. Numerous three‐dimensional (3‐D) tomographic models have been presented over the last 30 years and subsequently analyzed by a wider community of seismologists, geodynamicists, mineral physicists, and geochemists. However, platform‐independent, open source, user‐friendly software for interactive exploration of tomographic models does not exist. Here, we present a package for interactive visualization, analysis, and presentation of tomographic models. Using a set of four Matlab programs, multiscale tomographic models can be explored in Cartesian or spherical coordinate systems; data subsets can be extracted and combined; publication‐quality figures can be produced; and Virtual Reality Modeling Language (VRML) models can be produced for 3‐D visualization and publication on the World Wide Web. This type of freely available software package will encourage the distribution of tomographic models in a standardized form for independent peer review by the research community.
Coincident observations of lightning by the FORTE photodiode detector, the New Mexico Tech Lightning Mapping Array and the NLDN during STEPS
Authors: Noble Cynthia M. M. , Beasley William H. , Postawko Susan E. , Light T. E. L.
Published: April 2004

Opportunities for observation of lightning simultaneously from space and ground are relatively rare. One such opportunity for “ground truth” occurred during the STEPS field program. On 25 June, 2000 the FORTE Satellite passed over a storm that was also observed by a VHF Lightning Mapping Array (LMA). Of the 190 flashes mapped during the 2 minute 45 second pass, 26 had associated satellite optical data, and 3 of these were coincident with the only NLDN ground‐strike locations in the storm during that time. The maximum height, horizontal extent and duration of flashes detected optically tended to be greater than for those flashes not optically detected. Results in this paper, a companion paper and other published papers suggest that at least under some circumstances, CG flashes are relatively more likely than intra‐cloud (IC) flashes to be observed by an optical sensor in orbit.
Early coincident satellite optical and ground‐based RF observations of lightning
Authors: Beasley William H. , Edgar Bruce C.
Published: April 2004

The DMSP Piggy‐Back Experiment (PBE), was launched into polar orbit in 1977 to detect optical emissions from lightning. On August 8, 1977 it recorded 11 lightning flashes from a storm in the field of view for 2 minutes 36 seconds. During that period there were 8 cloud‐to‐ground (CG) flashes located by means of data recorded at two stations in Florida. Of these, 7 were coincident with optical signals. The optical waveforms coincident with the located CG flashes are different from those that were not coincident, and the differences are similar to the differences between CG and intra‐cloud flash (IC) optical signals recorded by the FORTE satellite. Satellite optical detection of 7 out of 8 CG flashes is consistent with results in a companion paper and other previous results, suggesting that CG flashes are relatively more likely than intra‐cloud (IC) flashes to be observed by an optical sensor in orbit.
Paleomagnetic dating of burial diagenesis in Mississippian carbonates, Utah
Authors: Blumstein Angela M. , Elmore R. Douglas , Engel Michael H. , Elliot Crawford , Basu Ankan
Published: April 2004

The objective of this study is to test models for the origin of widespread secondary magnetizations in the Mississippian Deseret Limestone. The Delle Phosphatic Member of the Deseret Limestone is a source rock for hydrocarbons, and modeling studies indicate that it entered the oil window in the Early Cretaceous during the Sevier orogeny. Paleomagnetic and rock magnetic results from the Deseret Limestone and the stratigraphically equivalent Chainman Shale in central and western Utah indicate that the units contain two ancient magnetizations residing in magnetite. Burial temperatures are too low for the magnetizations to be thermoviscous in origin, and they are interpreted to be chemical remanent magnetizations (CRMs). Fold tests from western Utah indicate the presence of a prefolding Triassic to Jurassic CRM. Geochemical (87Sr/86Sr, δ13C, and δ18O) and petrographic analyses suggest that externally derived fluids did not alter these rocks. This CRM was acquired at the beginning of the oil window and is interpreted to be the result of burial diagenesis of organic matter. A second younger CRM in western central Utah is apparently postfolding and is probably Late Cretaceous to early Tertiary in age. On the basis of the thermal modeling, the timing overlaps with the oil window. These results are consistent with a connection between organic matter maturation and remagnetization. Modeling of the smectite‐to‐illite transformation in the Deseret Limestone suggests a mean age prior to acquisition of both CRMs, although the range for illitization overlaps with the Triassic to Jurassic CRM. The results of this study support the hypothesis that pervasive CRMs can be related to burial diagenetic processes. In addition, paleomagnetism can be used to determine the timing of such processes, which can benefit hydrocarbon exploration efforts.
Streamflow and water balance intercomparisons of four land surface models in the North American Land Data Assimilation System project
Authors: Lohmann Dag , Mitchell Kenneth E. , Houser Paul R. , Wood Eric F. , Schaake John C. , Robock Alan , Cosgrove Brian A. , Sheffield Justin , Duan Qingyun , Luo Lifeng , Higgins R. Wayne , Pinker Rachel T. , Tarpley J. Dan
Published: April 2004

This paper is part of a series of papers about the multi‐institutional North American Land Data Assimilation System (NLDAS) project. It compares and evaluates streamflow and water balance results from four different land surface models (LSMs) within the continental United States. These LSMs have been run for the retrospective period from 1 October 1996 to 30 September 1999 forced by atmospheric observations from the Eta Data Assimilation System (EDAS) analysis, measured precipitation, and satellite‐derived downward solar radiation. These model runs were performed on a common 1/8° latitude‐longitude grid and used the same database for soil and vegetation classifications. We have evaluated these simulations using U.S. Geological Survey (USGS) measured daily streamflow data for 9 large major basins and 1145 small‐ to medium‐sized basins from 23 km2 to 10,000 km2 distributed over the NLDAS domain. Model runoff was routed with a common distributed and a lumped optimized linear routing model. The diagnosis of the model water balance results demonstrates strengths and weaknesses in the models, our insufficient knowledge of ad hoc parameters used for the model runs, the interdependence of model structure and model physics, and the lack of good forcing data in parts of the United States, especially in regions with extended snow cover. Overall, the differences between the LSM water balance terms are of the same magnitude as the mean water balance terms themselves. The modeled mean annual runoff shows large regional differences by a factor of up to 4 between models. The corresponding difference in mean annual evapotranspiration is about a factor of 2. The analysis of runoff timing for the LSMs demonstrates the importance of correct snowmelt timing, where the resulting differences in streamflow timing can be up to four months. Runoff is underestimated by all LSMs in areas with significant snowfall.
The multi‐institution North American Land Data Assimilation System (NLDAS): Utilizing multiple GCIP products and partners in a continental distributed hydrological modeling system
Authors: Mitchell Kenneth E. , Lohmann Dag , Houser Paul R. , Wood Eric F. , Schaake John C. , Robock Alan , Cosgrove Brian A. , Sheffield Justin , Duan Qingyun , Luo Lifeng , Higgins R. Wayne , Pinker Rachel T. , Tarpley J. Dan , Lettenmaier Dennis P. , Marshall Curtis H. , Entin Jared K. , Pan Ming , Shi Wei , Koren Victor , Meng Jesse , Ramsay Bruce H. , Bailey Andrew A.
Published: April 2004

Results are presented from the multi‐institution partnership to develop a real‐time and retrospective North American Land Data Assimilation System (NLDAS). NLDAS consists of (1) four land models executing in parallel in uncoupled mode, (2) common hourly surface forcing, and (3) common streamflow routing: all using a 1/8° grid over the continental United States. The initiative is largely sponsored by the Global Energy and Water Cycle Experiment (GEWEX) Continental‐Scale International Project (GCIP). As the overview for nine NLDAS papers, this paper describes and evaluates the 3‐year NLDAS execution of 1 October 1996 to 30 September 1999, a period rich in observations for validation. The validation emphasizes (1) the land states, fluxes, and input forcing of four land models, (2) the application of new GCIP‐sponsored products, and (3) a multiscale approach. The validation includes (1) mesoscale observing networks of land surface forcing, fluxes, and states, (2) regional snowpack measurements, (3) daily streamflow measurements, and (4) satellite‐based retrievals of snow cover, land surface skin temperature (LST), and surface insolation. The results show substantial intermodel differences in surface evaporation and runoff (especially over nonsparse vegetation), soil moisture storage, snowpack, and LST. Owing to surprisingly large intermodel differences in aerodynamic conductance, intermodel differences in midday summer LST were unlike those expected from the intermodel differences in Bowen ratio. Last, anticipating future assimilation of LST, an NLDAS effort unique to this overview paper assesses geostationary‐satellite‐derived LST, determines the latter to be of good quality, and applies the latter to validate modeled LST.
On advection and diffusion in the mesosphere and lower thermosphere: The role of rotational fluxes
Authors: Medvedev Alexander S. , Greatbatch Richard J.
Published: April 2004

A formalism to describe the advective and diffusive eddy transport in terms of the mean tracer is presented. It is based on Eulerian averaging, the flux‐gradient relation, and the decomposition of the eddy flux of a tracer into advective, diffusive, and rotational components. The rotational (nondivergent) flux arises because the conservation equation for the mean tracer contains only a divergence of the eddy flux of the tracer. To provide a closure, a modification to the flux separation technique based on the eddy variance equation is introduced. The “eddy‐induced” advective velocity is represented as the sum of two velocities v1 and v2. Velocity v1 is similar to that in the Transformed Eulerian Mean (TEM) formulation but is generalized to account for both horizontal and vertical eddy fluxes and mean gradients. The velocity v2 depends on the flux of eddy variance of the tracer. The diffusion coefficient is represented as a sum of K1, which may serve as a diagnostic of an irreversible mixing, and K2, which describes up‐ or down‐gradient eddy fluxes of the tracer due to local transformations of the eddy variance. Both v2 and K2 arise from taking account of the rotational fluxes. The scheme is applied to output from a global circulation model of the middle atmosphere. It is shown that in the meridional plane the correction v2 to the TEM velocity is small in the mesosphere and lower thermosphere. For the diffusion coefficient, however, the correction K2 must be accounted for above approximately 110 km.
The hydrogen isotopic composition of water vapor entering the stratosphere inferred from high‐precision measurements of δD‐CH4 and δD‐H2
Authors: McCarthy M. C. , Boering K. A. , Rahn T. , Eiler J. M. , Rice A. L. , Tyler S. C. , Schauffler S. , Atlas E. , Johnson D. G.
Published: April 2004

The hydrogen isotopic composition of water vapor entering the stratosphere provides an important constraint on the mechanisms for dehydration of air ascending through the tropical tropopause layer. We have inferred the annual mean hydrogen isotopic composition of water vapor entering the stratosphere (or δD‐H2O0) for the mid to late 1990s based on high‐precision measurements of the hydrogen isotopic compositions of stratospheric H2 and CH4 from whole air samples collected on the NASA ER‐2 aircraft between 1996 and 2000 and remote observations of δD‐H2O from the FIRS‐2 far infrared spectrometer. We calculate an annual mean value for δD‐H2O0 of −653 (+24/−25)‰ relative to Vienna standard mean ocean water (VSMOW). Previous inferences from balloon‐borne and spacecraft remote‐sensing observations are ∼20‰ lighter than the value from this analysis. We attribute the difference to an underestimation of deuterium in the molecular H2 reservoir in earlier work. This precise and more accurate value for the annual mean δD‐H2O0 will be useful as a 1990's benchmark for detecting future changes in the details of the dehydration of air due to the impact of climate change on convection intensity, cloud microphysics, or tropical tropopause layer temperatures. In addition, we report a value for the total deuterium content in the three main stratospheric hydrogen reservoirs HDO, HD, and CH3D of 1.60 (+0.02/−0.03) ppbv.
Drying front in a sloping aquifer: Nonlinear effects
Authors: Stagnitti Frank , Li Ling , Parlange J.‐Yves , Brutsaert Wilfried , Lockington David A. , Steenhuis Tammo S. , Parlange Marc B. , Barry D. A. , Hogarth William L.
Published: April 2004

The profiles for the water table height h(x, t) in a shallow sloping aquifer are reexamined with a solution of the nonlinear Boussinesq equation. We demonstrate that the previous anomaly first reported by Brutsaert [1994] that the point at which the water table h first becomes zero at x = L at time t = tc remains fixed at this point for all times t > tc is actually a result of the linearization of the Boussinesq equation and not, as previously suggested [Brutsaert, 1994; Verhoest and Troch, 2000], a result of the Dupuit assumption. Rather, by examination of the nonlinear Boussinesq equation the drying front, i.e., the point xf at which h is zero for times t ≥ tc, actually recedes downslope as physically expected. This points out that the linear Boussinesq equation should be used carefully when a zero depth is obtained as the concept of an “average” depth loses meaning at that time.
Carbon dioxide Earth degassing and seismogenesis in central and southern Italy
Authors: Chiodini G. , Cardellini C. , Amato A. , Boschi E. , Caliro S. , Frondini F. , Ventura G.
Published: April 2004

We present the first regional map of CO2 Earth degassing from a large area (most of central and south Italy) derived from the carbon of deep provenance dissolved in the main springs of the region. The investigation shows that a globally significant amount of deeply derived CO2 (10% of the estimated global CO2 emitted from subaerial volcanoes) is released by two large areas located in western Italy. The anomalous flux of CO2 suddenly disappears in the Apennine in correspondence to a narrow band where most of seismicity concentrates. Here, at depth, the gas accumulates in crustal traps generating CO2 overpressurized reservoirs which induce seismicity.
Evidence for enhanced coastal sea level rise during the 1990s
Authors: Holgate S. J. , Woodworth P. L.
Published: April 2004

Sea level rise over the last 55 years is estimated to have been 1.7 ± 0.2 mm yr−1, based upon 177 tide gauges divided into 13 regions with near global coverage and using a Glacial Isostatic Adjustment (GIA) model to correct for land movements. We present evidence from altimeter data that the rate of sea level rise around the global coastline was significantly in excess of the global average over the period 1993–2002. We also show that the globally‐averaged rate of coastal sea level rise for the decade centered on 1955 was significantly larger than any other decade during the past 55 years. In some models of sea level rise, enhanced coastal rise is a pre‐cursor of global average rise. It remains to be seen whether the models are correct and whether global‐average rates in the future reflect the high rates of coastal rise observed during the 1990s.
Neoproterozoic granitoid in northwest Sulu and its bearing on the North China‐South China Blocks boundary in east China
Authors: Wu Yuan‐Bao , Zheng Yong‐Fei , Zhou Jian‐Bo
Published: April 2004

Middle Neoproterozoic granitoid rocks are found in the Wulian region that is located in the northwestern part of the Sulu orogen and is approximately bounded by the Wulian‐Yantai fault in southeast. Zircon U‐Pb dating yields concordant ages of 738 ± 10 to 758 ± 5 Ma for three granites and one gabbro; hornblende Ar‐Ar dating on the gabbro gives consistent plateau and isochron ages of 719.1 ± 3.7 and 717.9 ± 7.2 Ma, respectively. This suggests that the Wulian granitoids correspond to bimodal magmatism during the mid‐Neoproterozoic in the northern margin of the South China Block in response to the breakup of Rodinia supercontinent. They were tectonic slices scraped off from the upper part of the South China Block during the Triassic continental subduction. This demonstrates that the suture location between the North China Block and the South China Block lies north of the Wulian and Penglai Groups rather than along the Wulian‐Yantai fault that marks the northern margin of ultrahigh pressure metamorphic belt.
Rapid disease development in scrapie‐infected mice deficient for CD40 ligand
Authors: Burwinkel Michael , Schwarz Anja , Riemer Constanze , Schultz Julia , van Landeghem Frank , Baier Michael
Published: April 2004

The inhibition of CD40–CD40L interaction‐mediated signalling was suggested as a therapeutic strategy for the treatment of Alzheimer's disease. Conversely, CD40‐deficient neurons were reported to be more vulnerable to stress associated with ageing as well as nerve growth factor‐β and serum withdrawal. We studied the scrapie infection of CD40L‐deficient (CD40L−/−) mice to see whether ablation of the CD40L gene would be beneficial or detrimental in this model of a neurodegenerative amyloidosis. CD40L−/− mice died on average 40 days earlier than wild‐type control mice and exhibited a more pronounced vacuolation of the neuropil and an increased microglia activation. The experimental model indicates that a deficiency for CD40L is highly detrimental in prion diseases and reinforces the neuroprotective function of intact CD40–CD40L interactions. The stimulation of neuroprotective pathways may represent a possibility to delay therapeutically the disease onset in prion infections of the central nervous system.
The absence of the yeast chromatin assembly factor Asf1 increases genomic instability and sister chromatid exchange
Authors: Prado Félix , Cortés‐Ledesma Felipe , Aguilera Andrés
Published: April 2004

Histone chaperone Asf1 participates in heterochromatin silencing, DNA repair and regulation of gene expression, and promotes the assembly of DNA into chromatin in vitro. To determine the influence of Asf1 on genetic stability, we have analysed the effect of asf1Δ on homologous recombination. In accordance with a defect in nucleosome assembly, asf1Δ leads to a loss of negative supercoiling in plasmids. Importantly, asf1Δ increases spontaneous recombination between inverted DNA sequences. This increase correlates with an accumulation of double‐strand breaks (DSBs) as determined by immunodetection of phosphorylated histone H2A and fluorescent detection of Rad52–YFP foci during S and G2/M phases. In addition, asf1Δ shows high levels of sister chromatid exchange (SCE) and is proficient in DSB‐induced SCE as determined by physical analysis. Our results suggest that defective chromatin assembly caused by asf1Δ leads to DSBs that can be repaired by SCE, affecting genetic stability.
Switching the mode of metabolism in the yeast Saccharomyces cerevisiae
Authors: Otterstedt Karin , Larsson Christer , Bill Roslyn M , Ståhlberg Anders , Boles Eckhard , Hohmann Stefan , Gustafsson Lena
Published: April 2004

The biochemistry of most metabolic pathways is conserved from bacteria to humans, although the control mechanisms are adapted to the needs of each cell type. Oxygen depletion commonly controls the switch from respiration to fermentation. However, Saccharomyces cerevisiae also controls that switch in response to the external glucose level. We have generated an S. cerevisiae strain in which glucose uptake is dependent on a chimeric hexose transporter mediating reduced sugar uptake. This strain shows a fully respiratory metabolism also at high glucose levels as seen for aerobic organisms, and switches to fermentation only when oxygen is lacking. These observations illustrate that manipulating a single step can alter the mode of metabolism. The novel yeast strain is an excellent tool to study the mechanisms underlying glucose‐induced signal transduction.
Dystroglycan, a scaffold for the ERK–MAP kinase cascade
Authors: Spence Heather J , Dhillon Amardeep S , James Marian , Winder Steven J
Published: April 2004

Dystroglycan is an important cell adhesion receptor linking the actin cytoskeleton, via utrophin and dystrophin, to laminin in the extracellular matrix. To identify adhesion‐related signalling molecules associated with dystroglycan, we conducted a yeast two‐hybrid screen and identified mitogen‐activated protein (MAP) kinase kinase 2 (MEK2) as a β‐dystroglycan interactor. Pull‐down experiments and localization studies substantiated a physiological link between β‐dystroglycan and MEK and localized MEK with dystroglycan in membrane ruffles. Moreover, we also identified active extracellular signal‐regulated kinase (ERK), the downstream kinase from MEK, as another interacting partner for β‐dystroglycan and localized both active ERK and dystroglycan to focal adhesions in fibroblast cells. These studies suggest a role for dystroglycan as a multifunctional adaptor or scaffold capable of interacting with components of the ERK–MAP kinase cascade including MEK and ERK. These findings have important implications for our understanding of the role of dystroglycan in normal cellular processes and in disease states such as muscular dystrophy.
Cracking the woody endocarp of Santalum spicatum nuts by wetting and rapid drying improves germination
Authors: Woodall G. S.
Published: April 2004

Seeds of many plant species, including those of sandalwood (Santalum spicatum (R.Br.) A.DC., Santalaceae), are surrounded by a fruit endocarp that is hard and woody (this structure hereafter referred to as a 'nut'). The woody endocarp of S. spicatum provides a physical barrier to germination. This study investigated how this barrier is removed and the mechanism(s) controlling it. Field trials demonstrated that the endocarp cracked naturally and that the time of harvest and the presence of the epicarp affected the percentage of endocarps that were cracked. An investigation of the influence of wetting period and rate of drying on endocarp cracking showed that the rate of drying was most critical in inducing cracking and that the process was not heat-dependent. Field and pot studies showed that germination of sown nuts was improved when the woody endocarp was fractured. Results suggest that a simple wetting and rapid drying procedure can be used to crack large amounts of sandalwood nuts prior to sowing in the field. Results are discussed in relation to S. spicatum seed ecology. The relevance of weakening the woody endocarp of other non-Santalum species through endocarp wetting and rapid drying is discussed.
Effect of developmental stage and peloton morphology on success in isolation of mycorrhizal fungi in Caladenia formosa (Orchidaceae)
Authors: Huynh T. T. , Lawrie A. C. , Coates F. , McLean C. B.
Published: April 2004

Six developmental stages (leafing, budding, flowering, fruiting, senescence and dormancy) were chosen in the threatened terrestrial orchid Caladenia formosa G.W.Carr to optimise isolation of effective fungi. Loose (undigested) pelotons were observed by scanning electron microscopy in the old tuber and collar, suggesting a role in infection of new tissue. In collars collected at early life stages (leafing, budding, flowering), pelotons had loosely coiled hyphae that were uniformly fine (1–2 μm diameter), with or without monilioid cells. In collars collected from older life stages (fruiting, senescence), pelotons had increasing proportions (up to 94%) of clumped fine hyphae. Coarser hyphae (4–6 μm diameter) were also present in the fruiting stage in one year. Only fungi isolated from single pelotons in collars of early life stages (leafing, budding, flowering) had fine hyphae with monilioid cells and induced seed germination (to green leaf production). Sectioned protocorms had pelotons of fine, loosely coiled hyphae with monilioid cells, as in field-collected material from early life stages. This suggests that the most effective fungi for conservation of this orchid are likely to be isolated from pelotons of loose fine hyphae with monilioid cells from leafing to flowering stages.
The role of cytokinins and thidiazuron in the stimulation of somatic embryogenesis in key members of the Restionaceae
Authors: Panaia M. , Senaratna T. , Dixon K. W. , Sivasithamparam K.
Published: April 2004

Rushes are important understorey species and comprise a significant component of pre-mined ecosystems. Re-establishment of rushes into disturbed sites has often been problematic. Several cytokinins and thidiazuron were investigated for the stimulation of somatic embryogenesis in key members of the Restionaceae. Somatic embryogenesis was observed for Desmocladus flexuosus (R.Br.) B.G.Briggs & L.A.S.Johnson with benzyladenine (BA) at 1, 5 or 15 μM alone and 1 μM 2,4-dichlorophenoxyacetic acid (2,4-D). The response to zeatin (Z) and 2iP-6-γ-γ-dimethyl-allyamino-purine (2iP) was negligible. For Baloskion tetraphyllum (J.J.H. de Labillardiere) B.G.Briggs & L.A.S.Johnson and Lyginia imberbis R.Br., BA, Z and 2iP were ineffective in stimulating any response.Somatic embryogenesis was achieved for B. tetraphyllum on 1/2-strength Murashige Skoog (1/2 MS) + 1 μM 2,4-D, with an estimated 14 000 somatic embryos produced from 1 g of plant material. All somatic embryos converted into plantlets and were successfully transferred to soil.Investigation of thidiazuron (TDZ) at 5 and 10 μM and 1 μM 2,4-D demonstrated that young coleoptiles (5–7 days) of B. tetraphyllum produced significantly more somatic embryos (168-fold more) than did older coleoptiles (>14 days). For D. flexuosus, leaf basal portions produced somatic embryos on 5 and 10 μM TDZ, and 5 μM TDZ + 1 μM 2,4-D. Proliferation of 'secondary somatic embryos' was also successful when somatic embryos were initiated on 10 μM TDZ and transferred to 1/2 MS (~9-fold increase).This study demonstrated variation in response among species of the same family, with D. flexuosus responding to BA and TDZ and B. tetraphyllum responding only to 2,4-D. The protocol investigated has the potential to be commercially viable with over 14 000 somatic embryos produced in 6 weeks for B. tetraphyllum.