bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of a Body-oriented Response Measure on the Neural Substrate of Imagined Perspective Rotations
Authors: Wraga Maryjane , Flynn Catherine M. , Boyle Holly K. , Evans Gretchen C. 
Published: July 2009

Abstract
Previous behavioral studies suggest that response measures related to the body, such as pointing, serve to anchor participants to their physical body during mental rotation tasks in which their perspective must be shifted elsewhere. This study investigated whether such measures engage spatial and low-level cortical motor areas of the brain more readily than non-body-related measures. We directly compared activation found in two imagined perspective rotation tasks, using responses that varied in the degree to which they emphasized the human body. In the body minimize condition, participants imagined rotating themselves around an object and judged whether a prescribed part of the object would be visible from the imagined viewpoint. In the body maximize condition, participants imagined rotating around the object and then located the prescribed object part with respect to their bodies. A direct comparison of neural activation in both conditions revealed distinct yet overlapping neural regions. The body maximize condition yielded activation in low-level cortical motor areas such as premotor cortex and primary motor cortex, as well as bilateral spatial processing areas. The body minimize condition yielded activation in nonmotoric egocentric processing regions. However, both conditions showed activation in the parietal–occipital region that is thought to be involved in egocentric transformations. These findings are discussed in the context of recent hypotheses regarding the role of the body percept in imagined egocentric transformations.
Characterizing the Spatio-temporal Dynamics of the Neural Events Occurring prior to and up to Overt Recognition of Famous Faces
Authors: Jemel Boutheina , Schuller Anne-Marie , Goffaux Valérie 
Published: July 2009

Abstract
Although it is generally acknowledged that familiar face recognition is fast, mandatory, and proceeds outside conscious control, it is still unclear whether processes leading to familiar face recognition occur in a linear (i.e., gradual) or a nonlinear (i.e., all-or-none) manner. To test these two alternative accounts, we recorded scalp ERPs while participants indicated whether they recognize as familiar the faces of famous and unfamiliar persons gradually revealed in a descending sequence of frames, from the noisier to the least noisy. This presentation procedure allowed us to characterize the changes in scalp ERP responses occurring prior to and up to overt recognition. Our main finding is that gradual and all-or-none processes are possibly involved during overt recognition of familiar faces. Although the N170 and the N250 face-sensitive responses displayed an abrupt activity change at the moment of overt recognition of famous faces, later ERPs encompassing the N400 and late positive component exhibited an incremental increase in amplitude as the point of recognition approached. In addition, famous faces that were not overtly recognized at one trial before recognition elicited larger ERP potentials than unfamiliar faces, probably reflecting a covert recognition process. Overall, these findings present evidence that recognition of familiar faces implicates spatio-temporally complex neural processes exhibiting differential pattern activity changes as a function of recognition state.
The Neural Basis for Spatial Relations
Authors: Amorapanth Prin X. , Widick Page , Chatterjee Anjan 
Published: July 2009

AbstractStudies in semantics traditionally focus on knowledge of objects. By contrast, less is known about how objects relate to each other. In an fMRI study, we tested the hypothesis that the neural processing of categorical spatial relations between objects is distinct from the processing of the identity of objects. Attending to the categorical spatial relations compared with attending to the identity of objects resulted in greater activity in superior and inferior parietal cortices (especially on the left) and posterior middle frontal cortices bilaterally. In an accompanying lesion study, we tested the hypothesis that comparable areas would be necessary to represent categorical spatial relations and that the hemispheres differ in their biases to process categorical or coordinate spatial relations. Voxel-based lesion symptom mapping results were consistent with the fMRI observations. Damage to a network comprising left inferior frontal, supramarginal, and angular gyri resulted in behavioral impairment on categorical spatial judgments. Homologous right brain damage also produced such deficits, albeit less severely. The reverse pattern was observed for coordinate spatial processing. Right brain damage to the middle temporal gyrus produced more severe deficits than left hemisphere damage. Additional analyses suggested that some areas process both kinds of spatial relations conjointly and others distinctly. The left angular and inferior frontal gyrus processes coordinate spatial information over and above the categorical processing. The anterior superior temporal gyrus appears to process categorical spatial information uniquely. No areas within the right hemisphere processed categorical spatial information uniquely. Taken together, these findings suggest that the functional neuroanatomy of categorical and coordinate processing is more nuanced than implied by a simple hemispheric dichotomy.
Connecting the Dots: How Local Structure Affects Global Integration in Infants
Authors: Palomares Melanie , Pettet Mark , Vildavski Vladimir , Hou Chuan , Norcia Anthony 
Published: July 2009

Abstract
Glass patterns are moirés created from a sparse random-dot field paired with its spatially shifted copy. Because discrimination of these patterns is not based on local features, they have been used extensively to study global integration processes. Here, we investigated whether 4- to 5.5-month-old infants are sensitive to the global structure of Glass patterns by measuring visual-evoked potentials. Although we found strong responses to the appearance of the constituent dots, we found sensitivity to the global structure of the Glass patterns in the infants only over a very limited range of spatial separation. In contrast, we observed robust responses in the infants when we connected the dot pairs of the Glass pattern with lines. Moreover, both infants and adults showed differential responses to exchanges between line patterns portraying different global structures. A control study varying luminance contrast in adults suggests that infant sensitivity to global structure is not primarily limited by reduced element visibility. Together our results suggest that the insensitivity to structure in conventional Glass patterns is due to inefficiencies in extracting the local orientation cues generated by the dot pairs. Once the local orientations are made unambiguous or when the interpolation span is small, infants can integrate these signals over the image.
Functional Overlap between Regions Involved in Speech Perception and in Monitoring One's Own Voice during Speech Production
Authors: Zheng Zane Z. , Munhall Kevin G. , Johnsrude Ingrid S. 
Published: July 2009

Abstract
The fluency and the reliability of speech production suggest a mechanism that links motor commands and sensory feedback. Here, we examined the neural organization supporting such links by using fMRI to identify regions in which activity during speech production is modulated according to whether auditory feedback matches the predicted outcome or not and by examining the overlap with the network recruited during passive listening to speech sounds. We used real-time signal processing to compare brain activity when participants whispered a consonant–vowel–consonant word (“Ted”) and either heard this clearly or heard voice-gated masking noise. We compared this to when they listened to yoked stimuli (identical recordings of “Ted” or noise) without speaking. Activity along the STS and superior temporal gyrus bilaterally was significantly greater if the auditory stimulus was (a) processed as the auditory concomitant of speaking and (b) did not match the predicted outcome (noise). The network exhibiting this Feedback Type × Production/Perception interaction includes a superior temporal gyrus/middle temporal gyrus region that is activated more when listening to speech than to noise. This is consistent with speech production and speech perception being linked in a control system that predicts the sensory outcome of speech acts and that processes an error signal in speech-sensitive regions when this and the sensory data do not match.
Probabilistic Parameterizations of Visibility Using Observations of Rain Precipitation Rate, Relative Humidity, and Visibility
Authors: Gultepe I. , Milbrandt J. A. 
Published: July 2009

Abstract
This study analyzes the occurrence of the visibility (Vis) versus precipitation rates (PR) for rain and versus relative humidity (RH) from surface observations that were collected during the Fog Remote Sensing and Modeling (FRAM) field project, which was conducted near Toronto, Ontario, Canada, during the winter of 2005/06 and in Lunenburg, Nova Scotia, during the summers of 2006 and 2007. The main observations used in the analysis were PR and Vis for rain episodes from the Vaisala, Inc., FD12P present-weather sensor and RH and temperature from the Campbell Scientific Instruments, Inc., HMP45 sensor. The PR is compared with those from a total precipitation sensor to check the accuracy of the FD12P measurements. Vis parameterizations related to precipitation type have been previously studied by many other researchers and showed large variability in Vis (up to 1 order of magnitude) for a fixed PR. The results from the work presented here suggest that 1) significant differences exist among the various parameterizations of Vis (deterministic approach) and 2) statistical relationships obtained using fits applied to percentiles (probabilistic approach) can be a feasible alternative for model applications. Comparisons of previous parameterizations with the new Vis relationships suggest that simulated Vis values based on probabilistic approaches could be used in extreme-weather applications.
A Method to Estimate Vertically Integrated Amounts of Cloud Ice and Liquid and Mean Rain Rate in Stratiform Precipitation from Radar and Auxiliary Data
Authors: Matrosov Sergey Y. 
Published: July 2009

Abstract
A method to retrieve total vertical amounts of cloud liquid and ice in stratiform precipitating systems is described. The retrievals use measurements from the vertically pointing Ka- and W-band cloud radars operated by the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) Program and auxiliary measurements from a scanning National Weather Service radar and a ground-based disdrometer. Separation between the cloud liquid and rain is based on estimations of the total attenuation of millimeter-wavelength radar signals in the liquid hydrometeor layer. Disdrometer measurements are used for the retrieval constraints. Because the liquid phase hydrometeor retrievals use only differential measurements, they are immune to the absolute radar calibration uncertainties. Estimates of the ice cloud phase are performed using empirical relations between absolute radar reflectivity and ice water content. Data from the nearby scanning weather-service radar, which operates at a lower frequency, are used to correct cloud radar measurements observed above the freezing level for attenuation caused by the layers of liquid and melting hydrometeors and also by wet radomes of cloud radars. Polarimetric and vertical Doppler measurements from ARM cloud radars provide a distinct separation between regions of liquid and ice phases, and therefore the corresponding retrievals are performed in each region separately. The applicability of the suggested method is illustrated for a stratiform precipitation event observed at the ARM Southern Great Plains facility. Expected uncertainties for retrievals of cloud liquid water path are estimated at about 200–250 g m−2 for typical rainfall rates observed in stratiform systems (∼3–4 mm h−1). These uncertainties increase as rainfall rate increases. The ice water path retrieval uncertainties can be as high as a factor of 2.
Preliminary Development and Evaluation of Lightning Jump Algorithms for the Real-Time Detection of Severe Weather
Authors: Schultz Christopher J. , Petersen Walter A. , Carey Lawrence D. 
Published: July 2009

Abstract
Previous studies have demonstrated that rapid increases in total lightning activity (intracloud + cloud-to-ground) are often observed tens of minutes in advance of the occurrence of severe weather at the ground. These rapid increases in lightning activity have been termed “lightning jumps.” Herein, the authors document a positive correlation between lightning jumps and the manifestation of severe weather in thunderstorms occurring across the Tennessee Valley and Washington D.C. A total of 107 thunderstorms from the Tennessee Valley; Washington, D.C.; Dallas, Texas; and Houston, Texas, were examined in this study. Of the 107 thunderstorms, 69 thunderstorms fall into the category of nonsevere and 38 into the category of severe. From the dataset of 69 isolated nonsevere thunderstorms, an average, peak, 1-min flash rate of 10 flashes per minute was determined. A variety of severe thunderstorm types were examined for this study, including a mesoscale convective system, mesoscale convective vortex, tornadic outer rainbands of tropical remnants, supercells, and pulse severe thunderstorms. Of the 107 thunderstorms, 85 thunderstorms (47 nonsevere, 38 severe) were from the Tennessee Valley and Washington, D.C., and these 85 thunderstorms tested six lightning jump algorithm configurations (Gatlin, Gatlin 45, 2σ, 3σ, Threshold 10, and Threshold 8). Performance metrics for each algorithm were then calculated, yielding encouraging results from the limited sample of 85 thunderstorms. The 2σ lightning jump algorithm had a high probability of detection (POD; 87%), a modest false-alarm rate (FAR; 33%), and a solid Heidke skill score (0.75). These statistics exceed current NWS warning statistics with this dataset; however, this algorithm needs further testing because there is a large difference in sample sizes. A second and more simplistic lightning jump algorithm named the Threshold 8 lightning jump algorithm also shows promise, with a POD of 81% and a FAR of 41%. Average lead times to severe weather occurrence for these two algorithms were 23 min. The overall goal of this study is to advance the development of an operationally applicable jump algorithm that can be used with either total lightning observations made from the ground, or in the near future from space using the Geostationary Operational Environmental Satellite Series R (GOES-R) Geostationary Lightning Mapper.
Simulated Electrification of a Small Thunderstorm with Two-Moment Bulk Microphysics
Authors: Mansell Edward R. , Ziegler Conrad L. , Bruning Eric C. 
Published: July 2009

Abstract
Electrification and lightning are simulated for a small continental multicell storm. The results are consistent with observations and thus provide additional understanding of the charging processes and evolution of this storm. The first six observed lightning flashes were all negative cloud-to-ground (CG) flashes, after which intracloud (IC) flashes also occurred between middle and upper levels of the storm. The model simulation reproduces the basic evolution of lightning from low and middle levels to upper levels. The observed lightning indicated an initial charge structure of at least an inverted dipole (negative charge above positive). The simulations show that noninductive charge separation higher in the storm can enhance the main negative charge sufficiently to produce negative CG flashes before upper-level IC flashes commence. The result is a “bottom-heavy” tripole charge structure with midlevel negative charge and a lower positive charge region that is more significant than the upper positive region, in contrast to the traditional tripole structure that has a less significant lower positive charge region. Additionally, the occurrence of cloud-to-ground lightning is not necessarily a result of excess net charge carried by the storm, but it is primarily caused by the local potential imbalance between the lowest charge regions.
The two-moment microphysics scheme used for this study predicted mass mixing ratio and number concentration of cloud droplets, rain, ice crystals, snow, and graupel. Bulk particle density of graupel was also predicted, which allows a single category to represent a greater range of particle characteristics. (An additional hail category is available but was not needed for the present study.) The prediction of hydrometeor number concentration is particularly critical for charge separation at higher temperatures (−5° &lt; T &lt; −20°C) in the mixed phase region, where ice crystals are produced by rime fracturing (Hallett–Mossop process) and by splintering of freezing drops. Cloud droplet concentration prediction also affected the rates of inductive charge separation between graupel and droplets.
Toward a Physically Based Gravity Wave Source Parameterization in a General Circulation Model
Authors: Richter Jadwiga H. , Sassi Fabrizio , Garcia Rolando R. 
Published: July 2009

Abstract
Middle atmospheric general circulation models (GCMs) must employ a parameterization for small-scale gravity waves (GWs). Such parameterizations typically make very simple assumptions about gravity wave sources, such as uniform distribution in space and time or an arbitrarily specified GW source function. The authors present a configuration of the Whole Atmosphere Community Climate Model (WACCM) that replaces the arbitrarily specified GW source spectrum with GW source parameterizations. For the nonorographic wave sources, a frontal system and convective GW source parameterization are used. These parameterizations link GW generation to tropospheric quantities calculated by the GCM and provide a model-consistent GW representation. With the new GW source parameterization, a reasonable middle atmospheric circulation can be obtained and the middle atmospheric circulation is better in several respects than that generated by a typical GW source specification. In particular, the interannual NH stratospheric variability is significantly improved as a result of the source-oriented GW parameterization. It is also shown that the addition of a parameterization to estimate mountain stress due to unresolved orography has a large effect on the frequency of stratospheric sudden warmings in the NH stratosphere by changing the propagation of stationary planetary waves into the polar vortex.
Aircraft Microphysical and Surface-Based Radar Observations of Summertime Arctic Clouds
Authors: Lawson R. Paul , Zuidema Paquita 
Published: July 2009

Abstract
Updated analyses of in situ microphysical properties of three Arctic cloud systems sampled by aircraft in July 1998 during the Surface Heat Budget of the Arctic Ocean (SHEBA)/First International Satellite Cloud Climatology Project (ISCCP) Regional Experiment–Arctic Clouds Experiment (FIRE–ACE) are examined in detail and compared with surface-based millimeter Doppler radar. A fourth case is given a cursory examination. The clouds were at 78°N over a melting ice surface, in distinctly different yet typical synoptic conditions. The cases comprise a midlevel all-ice cloud on 8 July; a deep, weakly forced, layered, mixed-phase stratus cloud system with pockets of drizzle, large dendrites, rimed ice and aggregates on 18 July; and a deep, mixed-phase cloud system with embedded convection on 28 July followed by an all-water boundary layer cloud on 29 July. The new observations include measured ice water content exceeding 2 g m−3 on 18 and 28 July and 3-cm snowflakes and 5-mm graupel particles on 28 July, unexpected in clouds close to the North Pole. Radar–aircraft agreement in reflectivity and derived microphysical parameters was reasonably good for the all-water and all-ice cases. In contrast, agreement in radar–aircraft reflectivity and derived parameters was generally inconsistent and sometimes poor for the two mixed-phase cases. The inconsistent agreement in radar–aircraft retrievals may be a result of large uncertainties in both instrument platforms and the algorithms used to retrieve derived parameters. The data also suggest that (single-wavelength) radar alone may not be capable of accurately retrieving the microphysical effects of cloud drops and drizzle in mixed-phase clouds, especially radiative properties such as extinction, albedo, and optical depth. However, more research is required before this generalization can be considered conclusive.
Distribution and Radiative Forcing of Tropical Thin Cirrus Clouds
Authors: Lee Joonsuk , Yang Ping , Dessler Andrew E. , Gao Bo-Cai , Platnick Steven 
Published: July 2009

AbstractTo understand the radiative impact of tropical thin cirrus clouds, the frequency of occurrence and optical depths of these clouds have been derived. “Thin” cirrus clouds are defined here as being those that are not detected by the operational Moderate Resolution Imaging Spectroradiometer (MODIS) cloud mask, corresponding to an optical depth value of approximately 0.3 or smaller, but that are detectable in terms of the cirrus reflectance product based on the MODIS 1.375-μm channel. With such a definition, thin cirrus clouds were present in more than 40% of the pixels flagged as “clear sky” by the operational MODIS cloud mask algorithm. It is shown that these thin cirrus clouds are frequently observed in deep convective regions in the western Pacific. Thin cirrus optical depths were derived from the cirrus reflectance product. Regions of significant cloud fraction and large optical depths were observed in the Northern Hemisphere during the boreal spring and summer and moved southward during the boreal autumn and winter. The radiative effects of tropical thin cirrus clouds were studied on the basis of the retrieved cirrus optical depths, the atmospheric profiles derived from the Atmospheric Infrared Sounder (AIRS) observations, and a radiative transfer model in conjunction with a parameterization of ice cloud spectral optical properties. To understand how these clouds regulate the radiation field in the atmosphere, the instantaneous net fluxes at the top of the atmosphere (TOA) and at the surface were calculated. The present study shows positive and negative net forcings at the TOA and at the surface, respectively. The positive (negative) net forcing at the TOA (surface) is due to the dominance of longwave (shortwave) forcing. Both the TOA and surface forcings are in a range of 0–20 W m−2, depending on the optical depths of thin cirrus clouds.