bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic Coding of Events within the Inferior Frontal Gyrus in a Probabilistic Selective Attention Task
Authors: Vossel Simone , Weidner Ralph , Fink Gereon R.
Published: February 2010

Besides the fact that RTs in cognitive tasks are affected by the specific demands of a trial, the context in which this trial occurs codetermines the speed of the response. For instance, invalid spatial cues generally prolong RTs to targets in the location-cueing paradigm, whereas the magnitude of these RT costs additionally varies as a function of the preceding trial types so that RTs for invalid trials may be increased when preceded by valid rather than invalid trials. In the present fMRI study, we investigated trial sequence effects in a combined oddball and location-cueing paradigm. In particular, we tested whether RTs and neural activity to infrequent invalid or deviant targets varied as a function of the number of preceding valid standard trials. As expected, RTs in invalid and deviant trials were significantly slower when more valid standard trials had been presented beforehand. This behavioral effect was reflected in the neural activity of the right inferior/middle frontal gyrus where the amplitude of the hemodynamic response in invalid and deviant trials was positively related to the number of preceding valid standard trials. In contrast, decreased activity (i.e., a negative parametric modulation effect) was observed when more valid standard trials were successively presented. Further positive parametric effects for the number of preceding valid standard trials were observed in the left caudate nucleus and lingual gyrus. The data suggest that inferior frontal cortex extracts both event regularities and irregularities in event streams.
Material-specific Neural Correlates of Recollection: Objects, Words, and Faces
Authors: Galli Giulia , Otten Leun J.
Published: February 2010

It is unclear how neural correlates of episodic memory retrieval differ depending on the type of material that is retrieved. Here, we used a source memory task to compare electrical brain activity for the recollection of three types of stimulus material. At study, healthy adults judged how well visually presented objects, words, and faces fitted with paired auditorily presented names of locations. At test, only visual stimuli were presented. The task was to decide whether an item had been presented earlier and, if so, what location had been paired with the item. Stimulus types were intermixed across trials in Experiment 1 and presented in separate study–test lists in Experiment 2. A graded pattern of memory performance was observed across objects, words, and faces in both experiments. Between 300 and 500 msec, event-related potentials for recollected objects and faces showed a more frontal scalp distribution compared to words in both experiments. Later in the recording epoch, all three stimulus materials elicited recollection effects over left posterior scalp sites. However, these effects extended more anteriorly for objects and faces when stimulus categories were blocked. These findings demonstrate that the neural correlates of recollection are material specific, the crucial difference being between pictorial and verbal material. Faces do not appear to have a special status. The sensitivity of recollection effects to the kind of experimental design suggests that, in addition to type of stimulus material, higher-level control processes affect the cognitive and neural mechanisms underlying episodic retrieval.
Identifying the What, Why, and How of an Observed Action: An fMRI Study of Mentalizing and Mechanizing during Action Observation
Authors: Spunt Robert P. , Satpute Ajay B. , Lieberman Matthew D.
Published: February 2010

Humans commonly understand the unobservable mental states of others by observing their actions. Embodied simulation theories suggest that this ability may be based in areas of the fronto-parietal mirror neuron system, yet neuroimaging studies that explicitly investigate the human ability to draw mental state inferences point to the involvement of a “mentalizing” system consisting of regions that do not overlap with the mirror neuron system. For the present study, we developed a novel action identification paradigm that allowed us to explicitly investigate the neural bases of mentalizing observed actions. Across repeated viewings of a set of ecologically valid video clips of ordinary human actions, we manipulated the extent to which participants identified the unobservable mental states of the actor (mentalizing) or the observable mechanics of their behavior (mechanizing). Although areas of the mirror neuron system did show an enhanced response during action identification, its activity was not significantly modulated by the extent to which the observers identified mental states. Instead, several regions of the mentalizing system, including dorsal and ventral aspects of medial pFC, posterior cingulate cortex, and temporal poles, were associated with mentalizing actions, whereas a single region in left lateral occipito-temporal cortex was associated with mechanizing actions. These data suggest that embodied simulation is insufficient to account for the sophisticated mentalizing that human beings are capable of while observing another and that a different system along the cortical midline and in anterior temporal cortex is involved in mentalizing an observed action.
Does Sleep Promote False Memories?
Authors: Darsaud Annabelle , Dehon Hedwige , Lahl Olaf , Sterpenich Virginie , Boly Mélanie , Dang-Vu Thanh , Desseilles Martin , Gais Stephen , Matarazzo Luca , Peters Frédéric , Schabus Manuel , Schmidt Christina , Tinguely Gilberte , Vandewalle Gilles , Luxen André , Maquet Pierre , Collette Fabienne
Published: February 2010

Memory is constructive in nature so that it may sometimes lead to the retrieval of distorted or illusory information. Sleep facilitates accurate declarative memory consolidation but might also promote such memory distortions. We examined the influence of sleep and lack of sleep on the cerebral correlates of accurate and false recollections using fMRI. After encoding lists of semantically related word associates, half of the participants were allowed to sleep, whereas the others were totally sleep deprived on the first postencoding night. During a subsequent retest fMRI session taking place 3 days later, participants made recognition memory judgments about the previously studied associates, critical theme words (which had not been previously presented during encoding), and new words unrelated to the studied items. Sleep, relative to sleep deprivation, enhanced accurate and false recollections. No significant difference was observed in brain responses to false or illusory recollection between sleep and sleep deprivation conditions. However, after sleep but not after sleep deprivation (exclusive masking), accurate and illusory recollections were both associated with responses in the hippocampus and retrosplenial cortex. The data suggest that sleep does not selectively enhance illusory memories but rather tends to promote systems-level consolidation in hippocampo-neocortical circuits of memories subsequently associated with both accurate and illusory recollections. We further observed that during encoding, hippocampal responses were selectively larger for items subsequently accurately retrieved than for material leading to illusory memories. The data indicate that the early organization of memory during encoding is a major factor influencing subsequent production of accurate or false memories.
Combining Functional Neuroimaging with Off-line Brain Stimulation: Modulation of Task-related Activity in Language Areas
Authors: Andoh Jamila , Paus Tomáš
Published: February 2010

Repetitive TMS (rTMS) provides a noninvasive tool for modulating neural activity in the human brain. In healthy participants, rTMS applied over the language-related areas in the left hemisphere, including the left posterior temporal area of Wernicke (LTMP) and inferior frontal area of Broca, have been shown to affect performance on word recognition tasks. To investigate the neural substrate of these behavioral effects, off-line rTMS was combined with fMRI acquired during the performance of a word recognition task. Twenty right-handed healthy men underwent fMRI scans before and after a session of 10-Hz rTMS applied outside the magnetic resonance scanner. Functional magnetic resonance images were acquired during the performance of a word recognition task that used English or foreign-language words. rTMS was applied over the LTMP in one group of 10 participants (LTMP group), whereas the homologue region in the right hemisphere was stimulated in another group of 10 participants (RTMP group). Changes in task-related fMRI response (English minus foreign languages) and task performances (response time and accuracy) were measured in both groups and compared between pre-rTMS and post-rTMS. Our results showed that rTMS increased task-related fMRI response in the homologue areas contralateral to the stimulated sites. We also found an effect of rTMS on response time for the LTMP group only. These findings provide insights into changes in neural activity in cortical regions connected to the stimulated site and are consistent with a hypothesis raised in a previous review about the role of the homologue areas in the contralateral hemisphere for preserving behavior after neural interference.
Language-universal Sensory Deficits in Developmental Dyslexia: English, Spanish, and Chinese
Authors: Goswami Usha , Wang H.-L. Sharon , Cruz Alicia , Fosker Tim , Mead Natasha , Huss Martina
Published: February 2010

Studies in sensory neuroscience reveal the critical importance of accurate sensory perception for cognitive development. There is considerable debate concerning the possible sensory correlates of phonological processing, the primary cognitive risk factor for developmental dyslexia. Across languages, children with dyslexia have a specific difficulty with the neural representation of the phonological structure of speech. The identification of a robust sensory marker of phonological difficulties would enable early identification of risk for developmental dyslexia and early targeted intervention. Here, we explore whether phonological processing difficulties are associated with difficulties in processing acoustic cues to speech rhythm. Speech rhythm is used across languages by infants to segment the speech stream into words and syllables. Early difficulties in perceiving auditory sensory cues to speech rhythm and prosody could lead developmentally to impairments in phonology. We compared matched samples of children with and without dyslexia, learning three very different spoken and written languages, English, Spanish, and Chinese. The key sensory cue measured was rate of onset of the amplitude envelope (rise time), known to be critical for the rhythmic timing of speech. Despite phonological and orthographic differences, for each language, rise time sensitivity was a significant predictor of phonological awareness, and rise time was the only consistent predictor of reading acquisition. The data support a language-universal theory of the neural basis of developmental dyslexia on the basis of rhythmic perception and syllable segmentation. They also suggest that novel remediation strategies on the basis of rhythm and music may offer benefits for phonological and linguistic development.
Is Neocortical–Hippocampal Connectivity a Better Predictor of Subsequent Recollection than Local Increases in Hippocampal Activity? New Insights on the Role of Priming
Authors: Gagnepain Pierre , Henson Richard , Chételat Gaël , Desgranges Béatrice , Lebreton Karine , Eustache Francis
Published: February 2010

During memory encoding, increased hippocampal activity—thought to reflect the binding of different types of information into unique episodes—has been shown to correlate with subsequent recollection of those episodes. Repetition priming—thought to induce more efficient perceptual processing of stimuli—is normally associated with decreased neocortical activity and is often assumed to reduce encoding into episodic memory. Here, we used fMRI to compare activity to primed and unprimed auditory words in the presence of distracting sounds as a function of whether participants subsequently recollected the word–sound associations or only had a feeling of familiarity with the word in a subsequent surprise recognition task. At the behavioral level, priming increased the incidence of subsequent recollection. At the neuronal level, priming reduced activity in the superior temporal gyrus (STG) but also reversed the traditional increase in encoding-related hippocampal activity associated with subsequent recollection relative to subsequent familiarity. To explain this interaction pattern, further analyses using dynamic causal modeling showed an increase in connectivity from left STG to left hippocampus specific to words that were later recollected. These findings show that successful episodic encoding is not determined solely by local hippocampal activity and emphasize instead the importance of increased functional neocortical–hippocampal coupling. Such coupling might be a better predictor of subsequent recollection than the direction of local hippocampal changes per se. We propose that one consequence of priming is to “free up” attentional resources from processing an item in a noisy context, thereby allowing greater attention to encoding of that context.
Two Processes for Recognition Memory in Children of Early School Age: An Event-related Potential Study
Authors: Mecklinger Axel , Brunnemann Nicole , Kipp Kerstin
Published: February 2010

We examined the ERP correlates of familiarity and recollection and their development in 8- to 10-year-old children and a control group of young adults. Capitalizing on the different temporal dynamics of familiarity and recollection, we tested recognition memory in both groups with a speeded and nonspeeded response condition. Consistent with the view that familiarity is available earlier than recollection and by this more relevant for speeded recognition judgments, adults and children showed an early frontal old/new effect, the putative ERP correlate of familiarity in the speeded response condition. No parietal old/new effect, the putative ERP correlate of recollection was obtained in the speeded condition in neither group. Conversely, in the nonspeeded condition, both groups showed the parietal old/new effect, and a frontal effect was additionally observed for adults. In light of the generally lower memory accuracy of the children, these data suggested that children use a weaker and less matured version of the same explicit memory network used by adults in which familiarity and recollection differentially contribute to speeded and nonspeeded recognition memory judgments.
Feedback-related Negativity Codes Prediction Error but Not Behavioral Adjustment during Probabilistic Reversal Learning
Authors: Chase Henry W. , Swainson Rachel , Durham Lucy , Benham Laura , Cools Roshan
Published: February 2010

We assessed electrophysiological activity over the medial frontal cortex (MFC) during outcome-based behavioral adjustment using a probabilistic reversal learning task. During recording, participants were presented two abstract visual patterns on each trial and had to select the stimulus rewarded on 80% of trials and to avoid the stimulus rewarded on 20% of trials. These contingencies were reversed frequently during the experiment. Previous EEG work has revealed feedback-locked electrophysiological responses over the MFC (feedback-related negativity; FRN), which correlate with the negative prediction error [Holroyd, C. B., & Coles, M. G. The neural basis of human error processing: Reinforcement learning, dopamine, and the error-related negativity. Psychological Review, 109, 679–709, 2002] and which predict outcome-based adjustment of decision values [Cohen, M. X., & Ranganath, C. Reinforcement learning signals predict future decisions. Journal of Neuroscience, 27, 371–378, 2007]. Unlike previous paradigms, our paradigm enabled us to disentangle, on the one hand, mechanisms related to the reward prediction error, derived from reinforcement learning (RL) modeling, and on the other hand, mechanisms related to explicit rule-based adjustment of actual behavior. Our results demonstrate greater FRN amplitudes with greater RL model-derived prediction errors. Conversely expected negative outcomes that preceded rule-based behavioral reversal were not accompanied by an FRN. This pattern contrasted remarkably with that of the P3 amplitude, which was significantly greater for expected negative outcomes that preceded rule-based behavioral reversal than for unexpected negative outcomes that did not precede behavioral reversal. These data suggest that the FRN reflects prediction error and associated RL-based adjustment of decision values, whereas the P3 reflects adjustment of behavior on the basis of explicit rules.
Putting the Pieces Together: The Role of Dorsolateral Prefrontal Cortex in Relational Memory Encoding
Authors: Blumenfeld Robert S. , Parks Colleen M. , Yonelinas Andrew P. , Ranganath Charan
Published: February 2010

Results from fMRI have strongly supported the idea that the ventrolateral PFC (VLPFC) contributes to successful memory formation, but the role the dorsolateral PFC (DLPFC) in memory encoding is more controversial. Some findings suggest that the DLPFC is recruited when one is processing relationships between items in working memory, and this processing specifically promotes subsequent memory for these relationships. However, previous studies could not rule out the possibility that DLPFC promotes memory during all elaborative encoding conditions and contributes to memory on all subsequent associative memory tests. To address this question directly, we used fMRI to examine activity during two encoding tasks that prompted participants to encode either relational or item-specific information. On relational trials, participants imagined pairs of items interacting, whereas on item-specific trials, participants imagined the items spatially separated and in different sizes. After scanning, we examined memory for relational information and item-specific information. fMRI results showed that DLPFC activity specifically promoted memory for relational information during relational encoding and not memory for item-specific information during item-specific encoding. In contrast, activity in the VLPFC predicted memory for both relational and item-specific information. The present results are consistent with the idea that the DLPFC specifically contributes to successful memory formation through its role in building relationships among items.
Steady-state Signatures of Visual Perceptual Load, Multimodal Distractor Filtering, and Neural Competition
Authors: Parks Nathan A. , Hilimire Matthew R. , Corballis Paul M.
Published: February 2010

The perceptual load theory of attention posits that attentional selection occurs early in processing when a task is perceptually demanding but occurs late in processing otherwise. We used a frequency-tagged steady-state evoked potential paradigm to investigate the modality specificity of perceptual load-induced distractor filtering and the nature of neural-competitive interactions between task and distractor stimuli. EEG data were recorded while participants monitored a stream of stimuli occurring in rapid serial visual presentation (RSVP) for the appearance of previously assigned targets. Perceptual load was manipulated by assigning targets that were identifiable by color alone (low load) or by the conjunction of color and orientation (high load). The RSVP task was performed alone and in the presence of task-irrelevant visual and auditory distractors. The RSVP stimuli, visual distractors, and auditory distractors were “tagged” by modulating each at a unique frequency (2.5, 8.5, and 40.0 Hz, respectively), which allowed each to be analyzed separately in the frequency domain. We report three important findings regarding the neural mechanisms of perceptual load. First, we replicated previous findings of within-modality distractor filtering and demonstrated a reduction in visual distractor signals with high perceptual load. Second, auditory steady-state distractor signals were unaffected by manipulations of visual perceptual load, consistent with the idea that perceptual load-induced distractor filtering is modality specific. Third, analysis of task-related signals revealed that visual distractors competed with task stimuli for representation and that increased perceptual load appeared to resolve this competition in favor of the task stimulus.
Estimation of Dissipative Heating Using Low-Level In Situ Aircraft Observations in the Hurricane Boundary Layer
Authors: Zhang Jun A.
Published: February 2010

Data collected in the low-level atmospheric boundary layer in five hurricanes by NOAA research aircraft are analyzed to measure turbulence with scales small enough to retrieve the rate of dissipation. A total of 49 flux runs suitable for analysis are identified in the atmospheric boundary layer within 200 m above the sea surface. Momentum fluxes are directly determined using the eddy correlation method, and drag coefficients are also calculated. The dissipative heating is estimated using two different methods: 1) integrating the rate of dissipation in the surface layer and 2) multiplying the drag coefficient by the cube of surface wind speed. While the latter method has been widely used in theoretical models as well as several numerical models simulating hurricanes, these analyses show that using this method would significantly overestimate the magnitude of dissipative heating. Although the dataset used in this study is limited by the surface wind speed range <30 m s−1, this work highlights that it is crucial to understand the physical processes related to dissipative heating in the hurricane boundary layer for implementing it into hurricane models.
Climate Modulation of North Atlantic Hurricane Tracks
Authors: Kossin James P. , Camargo Suzana J. , Sitkowski Matthew
Published: February 2010

The variability of North Atlantic tropical storm and hurricane tracks, and its relationship to climate variability, is explored. Tracks from the North Atlantic hurricane database for the period 1950–2007 are objectively separated into four groups using a cluster technique that has been previously applied to tropical cyclones in other ocean basins. The four clusters form zonal and meridional separations of the tracks. The meridional separation largely captures the separation between tropical and more baroclinic systems, while the zonal separation segregates Gulf of Mexico and Cape Verde storms. General climatologies of the seasonality, intensity, landfall probability, and historical destructiveness of each cluster are documented, and relationships between cluster membership and climate variability across a broad spectrum of time scales are identified.

Composites, with respect to cluster membership, of sea surface temperature and other environmental fields show that regional and remote modes of climate variability modulate the cluster members in substantially differing ways and further demonstrate that factors such as El Niño–Southern Oscillation (ENSO), Atlantic meridional mode (AMM), North Atlantic Oscillation (NAO), and Madden–Julian oscillation (MJO) have varying intrabasin influences on North Atlantic tropical storms and hurricanes. Relationships with African easterly waves are also considered. The AMM and ENSO are found to most strongly modulate the deep tropical systems, while the MJO most strongly modulates Gulf of Mexico storms and the NAO most strongly modulates storms that form to the north and west of their Cape Verde counterparts and closer to the NAO centers of action.

Different clusters also contribute differently to the observed trends in North Atlantic storm frequency and may be related to intrabasin differences in sea surface temperature trends. Frequency trends are dominated by the deep tropical systems, which account for most of the major hurricanes and overall power dissipation. Contrarily, there are no discernable trends in the frequency of Gulf of Mexico storms, which account for the majority of landfalling storms. When the proportion that each cluster contributes to overall frequency is considered, there are clear shifts between the deep tropical systems and the more baroclinic systems. A shift toward proportionally more deep tropical systems began in the early to mid-1980s more than 10 years before the 1995 North Atlantic hurricane season, which is generally used to mark the beginning of the present period of heightened activity.
Turbulence Patch Identification in Potential Density or Temperature Profiles
Authors: Wilson Richard , Luce Hubert , Dalaudier Francis , Lefrère Jacques
Published: February 2010

The Thorpe analysis is a recognized method used to identify and characterize turbulent regions within stably stratified fluids. By comparing an observed profile of potential temperature or potential density to a reference profile obtained by sorting the data, overturns resulting in statically unstable regions, mainly because of turbulent patches and Kelvin–Helmholtz billows, can be identified. However, measurement noise may induce artificial inversions of potential temperature or density, which can be very difficult to distinguish from real (physical) overturns.

A method for selecting real overturns is proposed. The method is based on the data range statistics; the range is defined as the difference between the maximum and the minimum of the values in a sample. A statistical hypothesis test on the range is derived and evaluated through Monte Carlo simulations. Basically, the test relies on a comparison of the range of a data sample with the range of a normally distributed population of the same size as the data sample. The power of the test, that is, the probability of detecting the existing overturns, is found to be an increasing function of both trend-to-noise ratio (tnr) and overturns size. A threshold for the detectable size of the overturns as a function of tnr is derived. For very low tnr data, the test is shown to be unreliable whatever the size of the overturns. In such a case, a procedure aimed to increase the tnr, mainly based on subsampling, is described.

The selection procedure is applied to atmospheric data collected during a balloon flight with low and high vertical resolutions. The fraction of the vertical profile selected as being unstable (turbulent) is 47% (27%) from the high (low) resolution dataset. Furthermore, relatively small tnr measurements are found to give rise to a poor estimation of the vertical extent of the overturns.
An Idealized Comparison of One-Way and Two-Way Grid Nesting
Authors: Harris Lucas M. , Durran Dale R.
Published: February 2010

Most mesoscale models can be run with either one-way (parasitic) or two-way (interactive) grid nesting. This paper presents results from a linear 1D shallow-water model to determine whether the choice of nesting method can have a significant impact on the solution. Two-way nesting was found to be generally superior to one-way nesting. The only situation in which one-way nesting performs better than two-way is when very poorly resolved waves strike the nest boundary. A simple filter is proposed for use exclusively on the coarse-grid values within the sponge zone of an otherwise conventional sponge boundary condition (BC). The two-way filtered sponge BC gives better results than any of the other methods considered in these tests. Results for all wavelengths were found to be robust to other changes in the formulation of the sponge boundary, particularly with the width of the sponge layer. The increased reflection for longer-wavelength disturbances in the one-way case is due to a phase difference between the coarse- and nested-grid solutions at the nested-grid boundary that accumulates because of the difference in numerical phase speeds between the grids. Reflections for two-way nesting may be estimated from the difference in numerical group velocities between the coarse and nested grids, which only becomes large for waves that are poorly resolved on the coarse grid.
Characteristics of Target Areas Selected by the Ensemble Transform Kalman Filter for Medium-Range Forecasts of High-Impact Winter Weather
Authors: Majumdar Sharanya J. , Sellwood Kathryn J. , Hodyss Daniel , Toth Zoltan , Song Yucheng
Published: February 2010

The characteristics of “target” locations of tropospheric wind and temperature identified by a modified version of the ensemble transform Kalman filter (ETKF), in order to reduce 0–7-day forecast errors over North America, are explored from the perspective of a field program planner. Twenty cases of potential high-impact weather over the continent were investigated, using a 145-member ensemble comprising perturbations from NCEP, ECMWF, and the Canadian Meteorological Centre (CMC).

Multiple targets were found to exist in the midlatitude storm track. In half of the cases, distinctive targets could be traced upstream near Japan at lead times of 4–7 days. In these cases, the flow was predominantly zonal and a coherent Rossby wave packet was present over the northern Pacific Ocean. The targets at the longest lead times were often located within propagating areas of baroclinic energy conversion far upstream. As the lead time was reduced, these targets were found to diminish in importance, with downstream targets corresponding to a separate synoptic system gaining in prominence. This shift in optimal targets is sometimes consistent with the radiation of ageostrophic geopotential fluxes and transfer of eddy kinetic energy downstream, associated with downstream baroclinic development. Concurrently, multiple targets arise due to spurious long-distance correlations in the ETKF. The targets were least coherent in blocked flows, in which the ETKF is known to be least reliable. The effectiveness of targeting in the medium range requires evaluation, using data such as those collected during the winter phase of The Observing System Research and Predictability Experiment (THORPEX) Pacific Asian Regional Field Campaign (T-PARC) in 2009.
Alternative Formulations for Incorporating Lateral Boundary Data into Limited-Area Models
Authors: Tudor Martina , Termonia Piet
Published: February 2010

Limited-area models (LAMs) use higher resolutions and more advanced parameterizations of physical processes than global numerical weather prediction models, but suffer from one additional source of error—the lateral boundary condition (LBC). The large-scale model passes the information on its fields to the LAM only over the narrow coupling zone at discrete times separated by a coupling interval of several hours. The LBC temporal resolution can be lower than the time necessary for a particular meteorological feature to cross the boundary. A LAM user who depends on LBC data acquired from an independent prior analysis or parent model run can find that usual schemes for temporal interpolation of large-scale data provide LBC data of inadequate quality. The problem of a quickly moving depression that is not recognized by the operationally used gridpoint coupling scheme is examined using a simple one-dimensional model. A spectral method for nesting a LAM in a larger-scale model is implemented and tested. Results for a traditional flow-relaxation scheme combined with temporal interpolation in spectral space are also presented.
Estimation and Mapping of Hurricane Turbulent Energy Using Airborne Doppler Measurements
Authors: Lorsolo Sylvie , Zhang Jun A. , Marks Frank , Gamache John
Published: February 2010

Hurricane turbulent kinetic energy (TKE) was computed using airborne Doppler measurements from the NOAA WP-3D tail radars, and TKE data were retrieved for a variety of storms at different stages of their life cycle. The geometry of the radar analysis coupled with the relatively small beam resolution at ranges <8 km allowed for the estimation of subkilometer turbulent processes. Two-dimensional profiles of TKE were constructed and revealed that the strongest turbulence was generally located in convective regions, such as the eyewall, with magnitudes often exceeding 15 m2 s−2 and in the boundary layer with values of 5–10 m2 s−2 in the lowest kilometer. A correlation analysis showed that the strong turbulence was generally associated with strong horizontal shear of vertical and radial wind components in the eyewall and strong vertical shear of horizontal wind in the boundary layer. Mean vertical profiles of TKE decrease sharply above the hurricane boundary layer and level off at low magnitude for all regions outside the radius of maximum wind.

The quality of the retrieval method was evaluated and showed very good agreement with TKE values directly calculated from the three-dimensional wind components of in situ measurements. The method presented here provides a unique opportunity to assess hurricane turbulence throughout the storm, especially in high-wind regions, and can be applied on extensive datasets of past and future airborne hurricane penetrations.
Life Cycle and Mesoscale Frontal Structure of an Intermountain Cyclone
Authors: West Gregory L. , Steenburgh W. James
Published: February 2010

High-resolution analyses and MesoWest surface observations are used to examine the life cycle and mesoscale frontal structure of the “Tax Day Storm,” an intermountain cyclone that produced the second lowest sea level pressure observed in Utah during the instrumented period and the strongest cold frontal passage at the Salt Lake City International Airport in the past 25 years. A key mesoscale surface feature contributing to the cyclone’s evolution is a confluence zone that extends downstream from the Sierra Nevada across the Great Basin. Strong contraction (i.e., deformation and convergence) within this Great Basin confluence zone (GBCZ) forms an airstream boundary that is initially nonfrontal but becomes the locus for surface frontogenesis as it collects and concentrates baroclinicity from the northern Great Basin, including that accompanying an approaching baroclinic trough. Evaporative and sublimational cooling from postfrontal precipitation, as well as cross-front contrasts in surface sensible heating, also play an important role, accounting for up to 40% of cross-front baroclinicity. As an upper-level cyclonic potential vorticity anomaly and quasigeostrophic forcing for ascent move over the Great Basin, cyclone development occurs along the GBCZ and developing cold front rather than within the Sierra Nevada lee trough, as might be inferred from classic models of lee cyclogenesis. Front–mountain interactions ultimately produce a very complex frontal evolution over the basin-and-range topography of northern Utah.

The analysis further establishes the role of the GBCZ in intermountain frontogenesis and cyclone evolution. Recognition of this role is essential for improving the analysis and prediction of sensible weather changes produced by cold fronts and cyclones over the Intermountain West.
The Antecedent Large-Scale Conditions of the “Perfect Storms” of Late October and Early November 1991
Authors: Cordeira Jason M. , Bosart Lance F.
Published: February 2010

The “Perfect Storms” (PSs) were a series of three high-impact extratropical cyclones (ECs) that impacted North America and the North Atlantic in late October and early November 1991. The PSs included the Perfect Storm in the northwest Atlantic, a second EC over the North Atlantic that developed from the interaction of the PS with Hurricane Grace, and a third EC over North America commonly known as the “1991 Halloween Blizzard.” The PSs greatly impacted the North Atlantic and North America with large waves, coastal flooding, heavy snow, and accumulating ice, and they also provided an opportunity to investigate the physical processes that contributed to a downstream baroclinic development (DBD) episode across North America that culminated in the ECs.

Downstream baroclinic development resulted from an amplification of the large-scale flow over the North Pacific that was influenced by anomalous tropical convection, the recurvature and extratropical transition of western North Pacific Tropical Cyclones Orchid, Pat, and Ruth, and the subsequent evolution of the extratropical flow. The progression of DBD occurred following the development of a negative PNA regime and the generation of baroclinic instability over North America associated with equatorward-displaced potential vorticity anomalies and poleward-displaced corridors of high moisture content. An analysis of the eddy kinetic energy tendency equation demonstrated that the resulting baroclinic conversion of eddy available potential energy into eddy kinetic energy during the cyclogenesis process facilitated the progression of DBD across North America and the subsequent development of the ECs.
Beyond Conspiracy Theory: Patterns of High Crime in American Government
Authors: deHaven-Smith Lance
Published: February 2010

This article explores the conceptual, methodological, and practical implications of research on state crimes against democracy (SCADs). In contrast to conspiracy theories, which speculate about each suspicious event in isolation, the SCAD construct delineates a general category of criminality and calls for crimes that fit this category to be examined comparatively. Using this approach, an analysis of post—World War II SCADs and suspected SCADs highlights a number of commonalities in SCAD targets, timing, and policy consequences. SCADs often appear where presidential politics and foreign policy intersect. SCADs differ from earlier forms of political corruption in that they frequently involve political, military, and/or economic elites at the very highest levels of the social and political order.The article concludes by suggesting statutory and constitutional reforms to improve SCAD prevention and detection.
Supplying Demand for Canada’s Knowledge Society: A Warmer Future for a Cold Climate?
Authors: Dufour Paul
Published: February 2010

Canada’s efforts to strengthen its talent and skills supply for the knowledge economy have been undergoing various transformations over the past decade, largely driven by immigration policy, global trends, and new science and technology investments. This article reviews some of the more recent experiments centered on building a knowledge culture with an assessment of selected strengths, gaps, and weaknesses while providing a commentary on the broader global effort that is affecting the Canadian discourse. It offers some guidelines on how Canada will need to build on existing infrastructure and governance, suggests key instruments for engaging its knowledge workforce, and points to some current directions for a warmer future for Canadian talent and the science culture.
Women and Men Faculty in Academic Science and Engineering: Social-Organizational Indicators and Implications
Authors: Fox Mary Frank
Published: February 2010

Drawing on recent survey data of women and men faculty in doctoral-granting departments in computer science, engineering, and science fields in nine highly ranked research universities, this article depicts four key social-organizational features of work, as reported by women and men respondents: frequency of speaking with faculty about research in home unit, ratings of aspects of position and department, characterizations of departmental climates, and levels of interference experienced with work and family.The article points to (a) the ways in which these features of work are consequential for significant status in academic science and engineering; (b) the ways in which experiences with these features vary for women and men faculty; and (c) the ways that institutional practices and policies, reflecting these features, may be improved toward greater equity for the full participation and status of both women and men in academic science and engineering.
Diversifying Science and Engineering Faculties: Intersections of Race, Ethnicity, and Gender
Authors: Leggon Cheryl B.
Published: February 2010

The fields of science, technology, engineering, and mathematics (STEM) drive economies worldwide. In such knowledge-based economies, no nation can afford to use its human resources inefficiently and ineffectively. Faculties exert a great deal of influence on the science and engineering (S&E) enterprise insofar as they conduct cutting-edge research as well as educate and train the S&E labor forces. This article focuses on the dynamics of the intersections of race/ethnicity and gender on diversifying S&E faculties in colleges and universities in the United States, and the criticality of disaggregating data to better understand these dynamics. Failure to disaggregate race/ethnicity data by gender, and gender data by race/ethnicity, masks important distinctions among groups. Failure to systematically take into account these distinctions results in policy, programs, practices, and institutions that are both inefficient and ineffective in developing and enhancing the S&E labor forces.
A Long View of America’s Immigration Policy and the Supply of Foreign-Born STEM Workers in the United States
Authors: Lindsay Lowell B.
Published: February 2010

The immigration policy of the United States has admitted generous numbers of skilled migrants. There was a steady increase from the 1950s and then notable growth following the acts of 1965 and 1990, including a substantial increase in the 1990s. Today, the foreign born make up one quarter of the workforce in the life and physical sciences, one fifth of information technology, and one sixth of the engineering workforce. Yet, many observers are concerned that the United States restricts the number of skilled immigrants, although it admits roughly 70,000 skilled primary workers yearly on permanent visas and roughly 300,000 on so-called temporary visas. Recent legislation addresses the concerns over numbers, however poorly framed those concerns are in reality, but it is arguable that the concern over numbers is misleading and there should be more focus on improving the admission process to efficiently admit the best foreign workers.
Vibro-acoustic Analysis of Composite Elliptic Disc with Various Orthotropic Properties
Authors: Boorle Rajesh Kumar  , Ganesan N. , Sethuraman Raju
Published: February 2010

Parametric studies are carried out on prediction of vibro-acoustic response from composite elliptic disc with elliptical and radial orthotropic fibers, varying minor axis ‘a’ and for different composite materials. Displacement, velocity, acceleration, radiated sound pressure, radiated sound power level, and radiation efficiency of the elliptic disc are examined over a range of varying frequencies. Vibration response due to harmonic point load was computed by finite element method (FEM) using ANSYS. Acoustic response of composite elliptic disc was computed by coupling the vibration data from FEM to the boundary element method using LMS SYSNOISE.
The Mechanical Properties of γ-Methacryloxypropyltrimethoxy silane-treated Jute/Polyester Composites
Authors: Sever Kutlay , Sarikanat Mehmet , Seki Yoldaş , Erkan Gökhan , Erdoğan Ümit Halis
Published: February 2010

In this study, jute/polyester composites were fabricated. To improve the adhesion between jute fabric and polyester alkali-treated jute fabrics were treated with γ-methacryloxypropyltrimethoxysilane (γ-MPS). The effect of silane concentrations (0.1%, 0.3%, and 0.5%) on tensile properties, flexural properties, and interlaminar shear strength was investigated. Once jute fabrics were treated with 0.1% and 0.3% silane concentrations, the tensile properties of silane-treated jute polyester composites increased. However, when 0.5% γ-MPS was used in silane treatment, the tensile properties of jute/polyester composites decreased. 0.3% silane-treated jute/polyester composites exhibited superior improvements in terms of the flexure properties among the fabricated composites. Interlaminar shear strength measurements showed that best adhesion was provided by using 0.3% silane-treated jute/polyester composites. Good adhesion between silane-treated jute fabric and polyester was also confirmed by scanning electron microscope observations.
The democratic peace research program and system-level analysis
Authors: Harrison Ewan
Published: February 2010

In a path-breaking article, Wade Huntley reinterpreted Kant’s pacific union as a systemic phenomenon. This generated a new wave of inquiry into the evolutionary expansion of the democratic peace. The resulting literature examines how the effects of the pacific union vary over time and with the strength of the global democratic community. It investigates the possibility that the democratic zone of peace may spread through spillover effects, socialization dynamics, and positive feedback. In so doing, it has moved democratic peace research beyond the ‘separate peace’ formulation. Currently, however, this literature has accumulated insights on an ad hoc basis. New hypotheses have been developed and tested without systematically considering how these insights contribute to established knowledge about the democratic peace. This article uses philosophy of science criteria to assess the contributions of the systemic democratic peace literature. It shows how systemic analysis of the democratic peace is progressive in terms of Lakatos’s methodology of scientific research programs. The article first considers how Lakatosian methodology has been applied to dyadic democratic peace research. Next, it refines this account of the democratic peace research program to make it more suitable for evaluating the contributions of the systemic literature. The last section shows systemic analysis is compatible with the Lakatosian vision of a cumulative series of theories (monadic-dyadic-systemic) building logically from a core assumption. It then uses the established structure of dyadic inquiry to frame a wide-ranging agenda for a second generation of democratic peace studies.
A Model in the Desert: Modernization, Advanced Liberalism, and Child Protection Reform in Postcommunist Romania
Authors: Negoita Marian
Published: February 2010

In this article, the author examines Romanian child protection reforms during European Union (EU) accession as a case of externally facilitated modernization aimed at solving acute social problems. The data for this case study came primarily from fifty-three unstructured interviews with civil servants, civil society representatives, and EU officials. The author finds that in a similar manner to other externally driven modernization projects, the belief according to which Western institutions constituted a universal blueprint, applicable regardless of particular contexts and historical legacies, led to unintended consequences. What is more, because the reformers did not envisage that Western institutions might carry their own pathologies, they ended up replicating some of these pathologies. The study suggests that the goal of externally facilitated public policy should not be to create replicas of Western institutions but to spur local innovation that takes advantage of successful Western institutional logics.
Institutionalizing Dualism: Complementarities and Change in France and Germany
Authors: Palier Bruno , Thelen Kathleen
Published: February 2010

The French and German political economies have been significantly reconfigured over the past two decades. Although the changes have often been more piecemeal than revolutionary, their cumulative effects are profound. The authors characterize the changes that have taken place as involving the institutionalization of new forms of dualism and argue that what gives contemporary developments a different character from the past is that dualism is now explicitly underwritten by state policy. They see this outcome as the culmination of a sequence of developments, beginning in the field of industrial relations, moving into labor market dynamics, and finally finding institutional expression in welfare state reforms. Contrary to theoretical accounts that suggest that institutional complementarities support stability and institutional reproduction, the authors argue that the linkages across these realms have helped to translate employer strategies that originated in the realm of industrial relations into a stable, new, and less egalitarian model with state support.