bluuebunny/crossref_metadata_2025 huggingface dataset:
The sympathoinhibitory effects of systemic cholecystokinin are dependent on neurons in the caudal ventrolateral medulla in the rat
Authors: Sartor D. M. , Verberne A. J. M.
Published: June 2006

The gastrointestinal hormone CCK inhibits a subset of presympathetic neurons in the rostroventrolateral medulla (RVLM) that may be responsible for driving the sympathetic vasomotor outflow to the gastrointestinal circulation. We tested the hypothesis that the central neurocircuitry of this novel sympathoinhibitory reflex involves a relay in the caudal ventrolateral medullary (CVLM) depressor area. Blood pressure and greater splanchnic sympathetic nerve discharge (SSND) or lumbar sympathetic nerve discharge (LSND) were monitored in anesthetised, paralyzed male Sprague-Dawley rats. The effects of phenylephrine (PE, 10 μg/kg iv; baroreflex activation), phenylbiguanide (PBG, 10 μg/kg iv; von Bezold-Jarisch reflex) and CCK (4 or 8 μg/kg iv) on SSND or LSND, were tested before and after bilateral injection of 50–100 nl of the GABAA agonist muscimol (1.75 mM; n = 6, SSND; n = 7, LSND) or the excitatory amino acid antagonist kynurenate (55 mM; n = 7, SSND) into the CVLM. PE and PBG elicited splanchnic and lumbar sympathoinhibitory responses that were abolished by bilateral muscimol or kynurenate injection into the CVLM. Similarly, the inhibitory effect of CCK on SSND was abolished after neuronal inhibition within the CVLM. In contrast, CCK-evoked lumbar sympathoexcitation was accentuated following bilateral CVLM inhibition. In control experiments ( n = 7), these agents were injected outside the CVLM and had no effect on splanchnic sympathoinhibitory responses to PE, PBG, and CCK. In conclusion, neurons in the CVLM are necessary for the splanchnic but not lumbar sympathetic vasomotor reflex response to CCK. This strengthens the view that subpopulations of RVLM neurons supply sympathetic vasomotor outflow to specific vascular territories.
MCA Vmean and the arterial lactate-to-pyruvate ratio correlate during rhythmic handgrip
Authors: Rasmussen Peter , Plomgaard Peter , Krogh-Madsen Rikke , Kim Yu-Sok , van Lieshout Johannes J. , Secher Niels H. , Quistorff Bjørn
Published: June 2006

Regulation of cerebral blood flow during physiological activation including exercise remains unknown but may be related to the arterial lactate-to-pyruvate (L/P) ratio. We evaluated whether an exercise-induced increase in middle cerebral artery mean velocity (MCA Vmean) relates to the arterial L/P ratio at two plasma lactate levels. MCA Vmean was determined by ultrasound Doppler sonography at rest, during 10 min of rhythmic handgrip exercise at ∼65% of maximal voluntary contraction force, and during 20 min of recovery in seven healthy male volunteers during control and a ∼15 mmol/l hyperglycemic clamp. Cerebral arteriovenous differences for metabolites were obtained by brachial artery and retrograde jugular venous catheterization. Control resting arterial lactate was 0.78 ± 0.09 mmol/l (mean ± SE) and pyruvate 55.7 ± 12.0 μmol/l (L/P ratio 16.4 ± 1.0) with a corresponding MCA Vmean of 46.7 ± 4.5 cm/s. During rhythmic handgrip the increase in MCA Vmean to 51.2 ± 4.6 cm/s was related to the increased L/P ratio (23.8 ± 2.5; r2 = 0.79; P < 0.01). Hyperglycemia increased arterial lactate and pyruvate to 1.9 ± 0.2 mmol/l and 115 ± 4 μmol/l, respectively, but it did not significantly influence the L/P ratio or MCA Vmean at rest or during exercise. Conversely, MCA Vmean did not correlate significantly, neither to the arterial lactate nor to the pyruvate concentrations. These results support that the arterial plasma L/P ratio modulates cerebral blood flow during cerebral activation independently from the plasma glucose concentration.
Neural Mechanisms Underlying Selectivity for the Rate and Direction of Frequency-Modulated Sweeps in the Inferior Colliculus of the Pallid Bat
Authors: Fuzessery Zoltan M. , Richardson Marlin D. , Coburn Michael S.
Published: June 2006

This study describes mechanisms that underlie neuronal selectivity for the direction and rate of frequency-modulated sweeps in the central nucleus of the inferior colliculus (ICC) of the pallid bat ( Antrozous pallidus). This ICC contains a high percentage of neurons (66%) that respond selectively to the downward sweep direction of the bat's echolocation pulse. Some (19%) are specialists that respond only to downward sweeps. Most neurons (83%) are also tuned to sweep rates. A two-tone inhibition paradigm was used to describe inhibitory mechanisms that shape selectivity for sweep direction and rate. Two different mechanisms can create similar rate tuning. The first is an early on-best frequency inhibition that shapes duration tuning, which in turn determines rate tuning. In most neurons that are not duration tuned, a delayed high-frequency inhibition creates rate tuning. These neurons respond to fast sweep rates, but are inhibited as rate slows, and delayed inhibition overlaps excitation. In these neurons, starting a downward sweep within the excitatory tuning curve eliminates rate tuning. However, if rate tuning is shaped by duration tuning, this manipulation has no effect. Selectivity for the downward sweep direction is created by an early low-frequency inhibition that prevents responses to upward sweeps. In addition to this asymmetry in arrival times of low- and high-frequency inhibitions, the bandwidth of the low-frequency sideband was broader. Bandwidth influences the arrival time of inhibition during an FM sweep because a broader sideband will be encountered sooner. These findings show that similar spectrotemporal filters can be created by different mechanisms.
Reduction of Intracortical Inhibition in Soleus Muscle During Postural Activity
Authors: Soto Oscar , Valls-Solé Josep , Shanahan Paul , Rothwell John
Published: June 2006

Short-interval intracortical inhibition (SICI) decreases during voluntary contraction of the target muscle. It is unknown whether this effect also occurs with postural contractions. We have compared the effects of voluntary and postural contractions on SICI in the soleus (SOL) muscle. We applied transcranial magnetic stimuli (TMS) in subjects under three tasks: sitting at rest (Rest), sitting while activating the SOL muscle (Voluntary), or standing quietly (Postural). In control trials, we applied suprathreshold TMS to obtain unconditioned motor-evoked potentials (MEPs). In test trials, the same TMS was preceded by a subthreshold TMS at different interstimulus intervals (ISIs), to obtain a conditioned MEP. SICI and intracortical facilitation (ICF) were expressed as the decrease or increase in MEP size relative to unconditioned MEPs. There was significant effect of task in mean SICI or mean ICF in SOL. Mean SICI in SOL was 52% in Rest and decreased to 21% in Voluntary and 15% in Postural. Mean ICF in SOL was 132% and decreased to 113% in Voluntary and to 108% in Postural. Mean SICI in SOL was not different in Voluntary and Postural tasks. There was no effect of task in mean SICI or mean ICF in TA. Our results indicate that decrease of SICI with muscle contraction occurs to a similar extent with tonic voluntary and postural activation, suggesting that those contractions require a similar type of cortical involvement. However, it cannot be excluded that some part of the SICI reduction with muscle contraction depends on changes in segmental excitability.
Responses to Noisy Periodic Stimuli Reveal Properties of a Neural Predictor
Authors: Joiner Wilsaan M. , Shelhamer Mark
Published: June 2006

In programming motor acts, the brain must consider both internal and external noise sources: inherent variation in sensory estimates and changes within the environment. An interesting question in motor control is how reliable responses can be programmed in the face of noise and how these two noise sources interact. We study this by investigating the generation of sequences of predictive saccades to visual targets. First, eight normal subjects tracked targets that alternated at a pacing frequency (0.9 Hz) that promoted predictive behavior, for 300 trials. When tracking this perfectly periodic stimulus, there was variability in the timing of the saccades (intersaccade intervals) that was distributed around the interval of the stimulus (556 ms). We used this inherent variability to set the timing of subsequent stimuli; subjects completed three additional sessions in which the variance of the stimulus timing (the interstimulus intervals) had the same (1.0 SD), less (0.5 SD), or more (2.0 SD) variability than the subject displayed when tracking the perfectly periodic stimulus. Despite changes in stimulus timing variability, variance of the response timing (intersaccade intervals) was equal to the variance of the stimulus plus “inherent variance” (response variance when tracking a perfectly periodic stimulus). Examining the correlations between saccade latency and interstimulus interval, this relationship is interpreted as a tradeoff between reliance on previous saccade performance (intertrial correlations) and reliance on the current stimulus.
Extraretinal Signals in MSTd Neurons Related to Volitional Smooth Pursuit
Authors: Ono Seiji , Mustari Michael J.
Published: June 2006

Smooth pursuit (SP)-related neurons in the dorsal-medial part of medial superior temporal cortex (MSTd) carry extraretinal signals that may play a role in maintenance of SP once eye velocity matches target velocity. For example, it has not been determined whether the extraretinal signals reflect volitional SP commands or proprioception. The aim of this study was to test some potential sources of extraretinal signals in MSTd pursuit neurons. We tested 40 MSTd neurons during step-ramp SP with target blink conditions to show that they carried an extraretinal signal. To examine potential contributions from eye movements that might reflect proprioceptive feedback from eye muscles, we tested MSTd neurons during rotational vestibular ocular reflex in complete darkness (VORd). Vestibular stimulation was delivered in the earth horizontal plane to elicit reflex driven smooth eye movements that matched the speed and frequency of volitional SP. We also tested VOR in the light (VORx1) and cancellation of the VOR (VORx0). Our neurons were modulated during both SP and cancellation of the VOR. In contrast, MSTd smooth pursuit neurons with extraretinal signals were not significantly modulated during VORd (sensitivity ≤ 0.10 spike/s/°/s). This combination of properties is compatible with classifying these neurons as gaze-velocity related. Absence of modulation during VORd testing could be caused by cancellation of head and eye movement sensitivity or dependence of neuronal firing on volitional SP commands. Our results support the suggestion that modulation of SP-related MSTd neurons reflects volitional SP commands rather then eye movements generated by reflex pathways.
Neuromagnetic Responses to Binaural Beat in Human Cerebral Cortex
Authors: Karino Shotaro , Yumoto Masato , Itoh Kenji , Uno Akira , Yamakawa Keiko , Sekimoto Sotaro , Kaga Kimitaka
Published: June 2006

The dichotic presentation of two sinusoids with a slight difference in frequency elicits subjective fluctuations called binaural beat (BB). BBs provide a classic example of binaural interaction considered to result from neural interaction in the central auditory pathway that receives input from both ears. To explore the cortical representation of the fluctuation of BB, we recorded magnetic fields evoked by slow BB of 4.00 or 6.66 Hz in nine normal subjects. The fields showed small amplitudes; however, they were strong enough to be distinguished from the noise accompanying the recordings. Spectral analyses of the magnetic fields recorded on single channels revealed that the responses evoked by BBs contained a specific spectral component of BB frequency, and the magnetic fields were confirmed to represent an auditory steady-state response (ASSR) to BB. The analyses of spatial distribution of BB-synchronized responses and minimum-norm current estimates revealed multiple BB ASSR sources in the parietal and frontal cortices in addition to the temporal areas, including auditory cortices. The phase of synchronized waveforms showed great variability, suggesting that BB ASSR does not represent changing interaural phase differences (IPD) per se, but instead it reflects a higher-order cognitive process corresponding to subjective fluctuations of BB. Our findings confirm that the activity of the human cerebral cortex can be synchronized with slow BB by using information on the IPD.
Linear Encoding of Muscle Activity in Primary Motor Cortex and Cerebellum
Authors: Townsend Benjamin R. , Paninski Liam , Lemon Roger N.
Published: June 2006

The activity of neurons in primary motor cortex (M1) and cerebellum is known to correlate with extrinsic movement parameters, including hand position and velocity. Relatively few studies have addressed the encoding of intrinsic parameters, such as muscle activity. Here we applied a generalized regression analysis to describe the relationship of neurons in M1 and cerebellar dentate nucleus to electromyographic (EMG) activity from hand and forearm muscles, during performance of precision grip by macaque monkeys. We showed that cells in both M1 and dentate encode muscle activity in a linear fashion, and that EMG signals provide predictions of neural discharge that are equally accurate to those from kinematic information under these task conditions. Neural activity in M1 was significantly more correlated with both EMG and kinematic signals than was activity in dentate nucleus. Furthermore, the analysis enabled us to look at the temporal properties of muscle encoding. Cells were broadly tuned to muscle activity as a function of the lag between spiking and EMG and there was considerable heterogeneity in the optimal delay among individual neurons. However, a single lag (40 ms) was generally sufficient to provide good fits. Finally, incorporating spike history effects in our model offered no advantage in predicting novel spike trains, reinforcing the simple nature of the muscle encoding that we observed here.
Evidence of Dual Pathways for Lipid Uptake during Chylomicron Remnant-Like Particle Processing by Human Macrophages
Authors: Napolitano Mariarosaria , Bravo Elena
Published: June 2006

Background: Though it is now clear that chylomicron remnants are pro-atherogenic lipoproteins, events leading to their incorporation by macrophages are poorly understood. Methods: This study investigates, in human macrophages, the fate of either [3H]cholesteryl oleate or [3H]triacylglycerol carried by human apolipoprotein-E-containing chylomicron remnant-like particles (CRLP) and the influence of CRLP containing trilinolein, (18:2)CRLP, or triolein, (18:1)CRLP, on lipid accumulation, newly synthesized cholesteryl ester (CE) and triacylglycerol (TG). Results: Labelled fatty acids from TG were markedly incorporated into TG and phospholipid and, to a lesser extent, into free fatty acids and were scarcely recovered in cholesteryl esters. [3H]CE from CRLP accumulated in cells in a dose-dependent manner with a significant difference between concentrations of 10 and 40 µg cholesterol/ml with (18:2)CRLP. In the same concentration range, TG synthesis was enhanced by about 46 and 30% by (18:2)CRLP and (18:1)CRLP cholesterol, respectively, whereas the esterification of cholesterol, evaluated by [3H]oleate incorporation, was decreased by about 30% with both types of CRLP. Endocytosis inhibition did not prevent cell cholesterol and TG accumulation, whereas lipoprotein lipase inhibition reduced the TG content. Conclusions: The results are consistent with the hypotheses that in macrophages dietary remnants may support TG and CE internalization via different mechanisms. Extracellular lipolysis seems particularly important for internalization of dietary fatty acids, whereas the entrance of CE seems attributable to a concomitant selective CE uptake mediated by scavenger receptor class B type I, since the scavenger receptor class B type I antibody induces significant inhibition (38%) of [3H]CE transported by CRLP, but does not affect internalization of [3H]TG carried by the same particles.
Growth Hormone Expression and Secretion in Pig Pituitary and Median Eminence Slices Are Not Influenced by the VGF Protein
Authors: Saleri Roberta , Cavalli Valeria , Grasselli Francesca , Tamanini Carlo
Published: June 2006

Body homeostasis is maintained by a complex system that involves the brain and the periphery via many circulating hormones. In recent years the VGF protein has been indicated as an important peptide affecting the regulation of body composition. We examined the effects of VGF on growth hormone (GH) expression and secretion in porcine pituitary slices, incubated alone (group 1) or with stalk median eminence (SME) (group 2). After 2 h (time 0), medium was removed and replaced with a fresh one; tissues were challenged with VGF (10–6M, 10–8 M) alone or with ghrelin (10–8M) or growth hormone-releasing hormone (GHRH) (10–8M). Medium was replaced again 2 h (+2) and 6 h (+6) later. None of the VGF concentrations influenced GH secretion in either group; the association with GHRH or ghrelin appeared ineffective in influencing GH secretion as compared with the effects of GH mRNA expression and was not influenced by VGF treatments. The presence of SME had an additive effect on GH expression. Collectively, our results confirm previous findings on GH regulation; however, further investigations are needed to establish whether the modulation of GH secretion in the absence of nutrients involves the balance of GHRH/ghrelin receptors at pituitary levels. As for VGF, a crucial aspect to clarify is whether its lack of effects depends on our experimental conditions or, alternatively, it is not effective at all.
Lack of Evidence for an Association Between Hemodynamic Variables and Hematoma Growth in Spontaneous Intracerebral Hemorrhage
Authors: Jauch Edward C. , Lindsell Christopher J. , Adeoye Opeolu , Khoury Jane , Barsan William , Broderick Joseph , Pancioli Arthur , Brott Thomas
Published: June 2006

Background and Purpose—

Early hematoma expansion in spontaneous intracerebral hemorrhage (ICH) is associated with worse clinical outcome. We hypothesized that hemodynamic parameters are associated with the increase in hematoma volume owing to their relationship to blood vessel wall stresses.

Methods—

We performed a post hoc analysis of clinical and computed tomography (CT) data from patients enrolled in a prospective observational study of ICH patients presenting within 3 hours from symptom onset. Hematoma volumes were measured at hospital arrival and at 1 and 20 hours from presentation. Blood pressure and heart rate, recorded at 19 time points between presentation and 20 hours, were used to derive hemodynamic variables. Multivariable logistic-regression models were constructed to assess the relation between hemodynamic parameters and hematoma growth, adjusted for clinical covariates.

Results—

From the original study, 98 patients underwent baseline and 1-hour CT scans; of these, 65 had 20-hour CT scans. Substantial hematoma growth was observed in 28% within the first hour. Of the 65 patients not undergoing surgery within 20 hours, 37% experienced hematoma growth by 20 hours. Neither baseline or peak hemodynamic parameters nor changes in hemodynamic parameters were significantly associated with hematoma growth at either 1 or 20 hours.

Conclusions—

We found no blood pressure or heart rate parameters, individually or in combination, that were associated with hematoma growth. Our data suggest the influence of hemodynamic parameters on vessel wall stress to be an unlikely target for intervention in reducing the risk of early hematoma growth in ICH.
Validation Study of the Siriraj Stroke Score in African Nigerians and Evaluation of the Discriminant Values of Its Parameters
Authors: Kolapo Kehinde O. , Ogun Shamsideen A. , Danesi Mustapha A. , Osalusi Bamidele Sanya , Odusote Kayode A.
Published: June 2006

Background and Purpose—

CT scanning is important to identify stroke pathology and exclude mimics. Its poor availability in our environment makes the search for simple, reliable clinical-score imperative. This study aims to validate the Siriraj Stroke score (SSS) and determine the discriminant values of its parameters in the black population of African-Nigerians.

Methods—

A prospective multicenter study was carried out on patients that presented with stroke and had brain CT scan done within 14 days of onset. An interviewer structured questionnaire was administered and SSS computed. The stroke-type was classified and compared with CT diagnosis. Data were analyzed using Epi-info-2002.

Results—

1122 patients presented with clinical features of stroke, of which only 101 (9%) could afford the cost of CT scan. Of these, 90 had CT-scan features consistent with acute stroke, 5 had cortical atrophy and 1 was normal. Thus, 96 patients were analyzed, of which 68 (71%) had cerebral ischemia and 28 (29%) had intracerebral hemorrhage. The 6 patients with no visible infarct on CT were regarded as cerebral infarction. The correlation between SSS, headache, vomiting, loss-of-consciousness and CT diagnosis achieved statistical significance, whereas atheroma markers and diastolic blood pressure did not. The SSS has an overall predictive accuracy of 80%.

Conclusions—

This preliminary study has shown that only 9% of our hospital stroke population had benefit of CT scan. The limited number of patients studied and their potential lack of representativeness, represent a funding issue to properly establish the performance of clinical scoring systems and assist in descriptive epidemiology of hospital and community-based stroke studies in resource-poor settings. However, in this study, the SSS diagnosis correlates significantly with CT diagnosis.
Poststroke Survival for Black-Caribbean Populations in Barbados and South London
Authors: Wolfe Charles D.A. , Corbin David O.C. , Smeeton Nigel C. , Gay Glenda H.E. , Rudd Anthony G. , Hennis Anselm J. , Wilks Rainford J. , Fraser Henry S.
Published: June 2006

Background and Purpose—

There are variations in mortality rates for stroke in black communities, but the factors associated with survival remain unclear.

Methods—

The authors studied population-based stroke registers with follow up in South London (270 participants, 1995 to 2002) and Barbados (578 participants, 2001 to 2003). Differences in sociodemographic factors, stroke risk factors and their management, case severity, and acute management between London and Barbados were studied. Survival analysis used Kaplan-Meier curves, log-rank test, and Cox proportional hazards model with stratification.

Results—

There were 1411 person-years of follow-up. Patients in Barbados had poorer survival (log-rank test
P
=0.037), particularly those with a prestroke Barthel index scores between 15 and 20 (1-year survival, 56.4% versus 74.3%;
P
<0.001). This disadvantage remained significant (hazard ratio [HR], 1.99; 95% CI, 1.23 to 3.21,
P
=0.005) after adjustment for age and year of stroke and stratification for stroke subtype and socioeconomic status (SES). After stratification by SES, clinical stroke subtype, and Glasgow Coma Score, and adjustment for other potential confounders, additional factors reducing survival were untreated atrial fibrillation (AF; HR, 8.54; 95% CI, 2.14 to 34.08,
P
=0.002), incontinence after stroke (HR, 2.64; 95% CI, 1.79 to 3.89), and dysphagia (HR, 2.25; 95% CI, 1.57 to 3.24). Patients not admitted to the hospital had improved survival (HR, 0.35; 95% CI, 0.21 to 0.58). Interaction terms between location and Barthel score, location and AF, and location and transient ischemic attack were included in the final model to reflect the greater difference in survival with a high Barthel score of 15 or more, absence of untreated AF, and having untreated transient ischemic attack.

Conclusions—

Black-Caribbean people with stroke living in Barbados have worse survival than similar patients in South London, particularly if they have good mobility before the stroke. Further exploration and refinement of measurement of confounding factors such as SES and poststroke management along with exploring the cultural/environmental differences between the communities is required to understand these stark differences.
Factors Associated With Geographic Variations in Stroke Incidence Among Older Populations in Four US Communities
Authors: El-Saed Aiman , Kuller Lewis H. , Newman Anne B. , Lopez Oscar , Costantino Joseph , McTigue Kathleen , Cushman Mary , Kronmal Richard
Published: June 2006

Background and Purpose—

In the Cardiovascular Health Study (CHS), we previously observed lower stroke incidence in Allegheny County, PA compared with the other 3 study sites. The purpose of this study was to study possible reasons for the lower stroke incidence in Allegheny County.

Methods—

CHS participants 65 years or older who were stroke-free at baseline (n=5639) were followed between 1989 to 1990 and 2000 for the development of stroke. Risk factors at baseline and their subsequent control were compared among both groups. Site-specific hazard ratios for stroke incidence were calculated using Cox regression models.

Results—

The unadjusted hazard ratio for total stroke incidence in Forsyth County, NC; Sacramento County, CA; and Washington County, MD combined compared with Allegheny County, PA was 1.74 (95% CI: 1.42, 2.14). After adjustment for age and other traditional risk factors, there was modest reduction of the excess hazard in non-Allegheny sites compared with Allegheny County (hazard ratio=1.52, 95% CI: 1.17, 1.98). Between baseline and the seventh-year visits, control of hypertension, diabetes, lipids, smoking, atrial fibrillation and transient ischemic attack were similar across sites. White matter grade ≥3 on the baseline brain MRI was less common in Allegheny County (25.8% versus 36.3%, respectively;
P
<0.001) and accounted for 25% of the excess hazard in non-Allegheny sites compared with Allegheny County.

Conclusions—

Site differences in stroke risk factors at baseline and subsequent control only partially explain site differences in stroke incidence. White matter grade as a possible integrated measure of exposure and control of risk factors may help in explaining geographic variations in stroke incidence.
Dispersion of Perfluorocarbon Tracers within the Salt Lake Valley during VTMX 2000
Authors: Fast Jerome D. , Allwine K. Jerry , Dietz Russell N. , Clawson Kirk L. , Torcolini Joel C.
Published: June 2006

Six perfluorocarbon tracer experiments were conducted in Salt Lake City, Utah, during October 2000 as part of the Vertical Transport and Mixing (VTMX) field campaign. Four tracers were released at different sites to obtain information on dispersion during stable conditions within down-valley flow, canyon outflow, and interacting circulations in the downtown area. Some of the extensive tracer data that were collected are presented in the context of the meteorological field campaign measurements. Tracer measurements at building-top sites in the downtown area and along the lower slopes of the Wasatch Front indicated that vertical mixing processes transported material up to at least 180 m above the valley floor, although model simulations suggest that tracers were transported upward to much higher elevations. Tracer data provided evidence of downward mixing of canyon outflow, upward mixing within down-valley flow, horizontal transport above the surface stable layer, and transport within horizontal eddies produced by the interaction of canyon and down-valley flows. Although point meteorological measurements are useful in evaluating the forecasts produced by mesoscale models, the tracer data provide valuable information on how the time-varying three-dimensional mean and turbulent motions over urban and valley spatial scales affect dispersion. Although the mean tracer transport predicted by the modeling system employed in this study was qualitatively similar to the measurements, improvements are needed in the treatment of turbulent vertical mixing.
Bowing Convective Systems in a Popular Operational Model: Are They for Real?
Authors: Bukovsky Melissa S. , Kain John S. , Baldwin Michael E.
Published: June 2006

Bowing, propagating precipitation features that sometimes appear in NCEP's North American Mesoscale model (NAM; formerly called the Eta Model) forecasts are examined. These features are shown to be associated with an unusual convective heating profile generated by the Betts–Miller–Janjić convective parameterization in certain environments. A key component of this profile is a deep layer of cooling in the lower to middle troposphere. This strong cooling tendency induces circulations that favor expansion of parameterized convective activity into nearby grid columns, which can lead to growing, self-perpetuating mesoscale systems under certain conditions. The propagation characteristics of these systems are examined and three contributing mechanisms of propagation are identified. These include a mesoscale downdraft induced by the deep lower-to-middle tropospheric cooling, a convectively induced buoyancy bore, and a boundary layer cold pool that is indirectly produced by the convective scheme in this environment. Each of these mechanisms destabilizes the adjacent atmosphere and decreases convective inhibition in nearby grid columns, promoting new convective development, expansion, and propagation of the larger system. These systems appear to show a poor correspondence with observations of bow echoes on time and space scales that are relevant for regional weather prediction, but they may provide important clues about the propagation mechanisms of real convective systems.
Forecasting Tornadic Thunderstorm Potential in Alberta Using Environmental Sounding Data. Part I: Wind Shear and Buoyancy
Authors: Dupilka Max L. , Reuter Gerhard W.
Published: June 2006

This study investigates, for Alberta, Canada, whether observed sounding parameters such as wind shear and buoyant energy can be used to help distinguish between thunderstorms with significant (F2–F5) tornadoes, thunderstorms with weak (F0–F1) tornadoes, and nontornadic severe thunderstorms. The observational dataset contains 87 severe convective storms, all of which occurred within 200 km of the upper-air site at Stony Plain, Alberta, Canada. Of these storms, 13 spawned significant (F2–F5) tornadoes, 61 spawned weak (F0–F1) tornadoes, and 13 had no reported tornadoes yet produced 3 cm or larger hailstones. The observations suggest that bulk shear contained information about the probability of tornado formation and the intensity of the tornado. Significant tornadic storms tended to have stronger shear values than weak tornadic or nontornadic severe storms. All significant tornado cases had a wind shear magnitude in the 900–500-mb layer exceeding 3 m s−1 km−1. Combining the 900–500-mb shear with the 900–800-mb shear increased the probabilistic guidance for the likelihood of significant tornado occurrence. The data suggest that buoyant energy alone (quantified by the most unstable convective available potential energy) provided no skill in discriminating between tornadic and nontornadic severe storms, or between significant and weak tornadoes.
Detection of Storm Damage Tracks with EOS Data
Authors: Jedlovec Gary J. , Nair Udaysankar , Haines Stephanie L.
Published: June 2006

The damage surveys conducted by the NWS in the aftermath of a reported tornadic event are used to document the location of the tornado ground damage track (pathlength and width) and an estimation of the tornado intensity. This study explores the possibility of using near-real-time medium and high spatial resolution satellite imagery from the NASA Earth Observing System satellites to provide additional information for the surveys. Moderate Resolution Imaging Spectroradiometer (MODIS) and Advanced Space-borne Thermal Emission and Reflection Radiometer (ASTER) data were used to study the damage tracks from three tornadic storms: the La Plata, Maryland, storm of 28 April 2002 and the Ellsinore and Marquand, Missouri, storms of 24 April 2002. These storms varied in intensity and occurred over regions with significantly different land cover. It was found that, depending on the nature of the land cover, tornado damage tracks from intense storms (F1 or greater) and hail storms may be evident in ASTER, Landsat, and MODIS satellite imagery. In areas where the land cover is dominated by forests, the scar patterns can show up very clearly, while in areas of grassland and regions with few trees, scar patterns are not as obvious or cannot be seen at all in the satellite imagery. The detection of previously unidentified segments of a damage track caused by the 24 April 2002 Marquand, Missouri, tornado demonstrates the utility of satellite imagery for damage surveys. However, the capability to detect tornado tracks in satellite imagery depends on the ability to observe the ground without obstruction from space and appears to be as much dependent on the nature of the underlying surface and land cover as on the severity of the tornadic storm.
An Integrated Approach to Mid- and Upper-Level Turbulence Forecasting
Authors: Sharman R. , Tebaldi C. , Wiener G. , Wolff J.
Published: June 2006

An automated procedure for forecasting mid- and upper-level turbulence that affects aircraft is described. This procedure, termed the Graphical Turbulence Guidance system, uses output from numerical weather prediction model forecasts to derive many turbulence diagnostics that are combined as a weighted sum with the relative weights computed to give best agreement with the most recent available turbulence observations (i.e., pilot reports of turbulence or PIREPs). This procedure minimizes forecast errors due to uncertainties in individual turbulence diagnostics and their thresholds. Thorough statistical verification studies have been performed that focused on the probabilities of correct detections of yes and no PIREPs by the forecast algorithm. Using these statistics as a guide, the authors have been able to intercompare individual diagnostic performance, and test various diagnostic threshold and weighting strategies. The overall performance of the turbulence forecast and the effect of these strategies on performance are described.
The Use of Global and Mesoscale Meteorological Model Data to Predict the Transport and Dispersion of Tracer Plumes over Washington, D.C.
Authors: Draxler Roland R.
Published: June 2006

The data from a yearlong tracer dispersion experiment over Washington, D.C., in 1984 were used to evaluate Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) dispersion model calculations using coarse global meteorological reanalysis data [NCEP–NCAR and 40-Yr ECMWF Re-Analysis (ERA-40)] and calculations using meteorological data fields created by running a high-resolution meteorological model [fifth-generation Pennsylvania State University–NCAR Mesoscale Model (MM5)]. None of the meteorological models were optimized for urban environments. The dispersion calculation using the ERA-40 data showed better performance than those using the NCEP–NCAR data and comparable performance to those using MM5 data fields. Calculations with MM5 data that used shorter-period forecasts were superior to calculations that used forecast data that extended beyond 24 h. Daytime dispersion model calculations using the MM5 data showed an underprediction bias not evident in calculations using the ERA-40 data or for nighttime calculations using either meteorological dataset. It was found that small changes in the wind direction for all meteorological model data resulted in dramatic improvements in dispersion model performance. All meteorological data modeled plume directions were biased 10°–20° clockwise to the measured plume direction. This bias was greatest when using the global meteorological data. A detailed analysis of the wind observations during the November intensive, which had the greatest difference between the model and measured plume directions, showed that only the very lowest level of observed winds could account for the transport direction of the measured plume. In the Northern Hemisphere, winds tend to turn clockwise with height resulting in positive directional transport bias if the lowest-level winds are not represented in sufficient detail by the meteorological model.
Teaching popular music in Finland: what's up, what's ahead?
Authors: Väkevä Lauri
Published: June 2006

This article describes the history and current situation of popular music pedagogy in Finland. While popular music is widely accepted in the curriculum, there are differences in its application in the comprehensive schools and music institutions. Popular styles were first introduced into Finnish music education by secondary school music teachers; however, today the most rapid development in the field appears to be taking place in the professional schools of music. Some aspects and future possibilities of popular music education are examined, with a suggestion that there is more work ahead in the field of general music education. For instance, the didactic implications of different learning cultures of popular music and the musical understandings and practices prevalent in ‘urban’ and ‘electronic’ styles present new challenges for traditionally trained music educators, even those with a popular music background.
Vernacular music-making and education
Authors: O'Flynn John
Published: June 2006

This article examines the division of music styles according to the conventional categories of classical, traditional and popular, and proposes the term ‘vernacular’ as a complementary way of viewing various types of amateur music-making among diverse groups in modern societies. ‘Vernacular’, as it is used here, includes the idea of relatively distinct musical communities as well as more fluid networks and scenes. The article exposes the historical basis and problematic nature of style categorizations, and adapts a theoretical model of music production modes that highlights the interconnectedness of various genres and practices of vernacular music. Critical to this analysis is the dialectical interplay between style categorizations, between participatory and performance modes of production, and between vernacular music-making and the consumption of broadcast and recorded musical products. The article concludes by suggesting that the mapping of amateur music-making practices (including formal and informal methods of teaching and learning) can contribute to school- and college-based systems of music education.
Contemporary music student expectations of musicianship training needs
Authors: Hannan Michael
Published: June 2006

The practical training of contemporary popular musicians, that is, the preparation of performers, songwriters, and music production personnel for the global popular music industry, is still in its infancy. This article seeks to discuss the specific issue of what musicianship skills should be taught, by interrogating the perceptions of a cohort of students studying for the Bachelor of Contemporary Music degree at Southern Cross University in Australia. Determining appropriate musicianship training programs for musicians in popular music is problematic because of the wide range of genres and professional practices involved in the field. Thus it seems to make good sense to tease out what music students themselves think about their support training needs. This small-scale study of 43 students in the first and second year of their degree shows that performance, composition and music production students have different musicianship-skill learning priorities.
Exploring the outcomes of rock and popular music instruction in high school guitar class: a case study
Authors: Seifried Scott
Published: June 2006

The purpose of this study was to better understand the impact of rock and popular teenage music on public school music education programs. ‘Frankstown Secondary School’ is a large suburban public school offering a guitar program that includes a strong popular music component. Subjects in this study were selected from students enrolled in Frankstown's guitar program. They participated in two rounds of in-depth interviews, which were recorded, transcribed and analyzed. The guitar program at Frankstown emerged as a powerful educational tool. Students who deliberately ‘chose the margin’ or adopted ‘oppositional frames’ found a program that explicitly embraced the margin. Guitar class was a place where the students seemed comfortable; a place where they were able to ‘act out’ their oppositional persona within the larger Frankstown culture – a place that accepted them as they were and was a product of their own negotiations with the instructor and one another.
Pop and world music in Dutch music education: two cases of authentic learning in music teacher education and secondary music education
Authors: Evelein Frits
Published: June 2006

Popular and world music play an important role in Dutch music education. This article examines two case studies that illustrate authentic music learning environments in which these types of music are prominently used. The first case follows a student during her training at the Rotterdam Academy for Music Education, in which her own musical and teaching experiences are crucial elements of her training. The second case focuses on a recently published music methodology in the Netherlands called Soundcheck. Following this methodology, pupils in secondary education are stimulated by playing in groups on real instruments, using pop and world music. Reflecting on their musical experiences helps them to learn more about music. These case studies illustrate in a practical sense the dynamics of authentic music learning in schools and in a music teacher education programme in the multicultural environment of Rotterdam.
Management of Osteochondritis Dissecans of the Knee
Authors: Kocher Mininder S. , Tucker Rachael , Ganley Theodore J. , Flynn John M.
Published: June 2006

Osteochondritis dissecans of the knee is being seen with increased frequency in pediatric and young adult athletes and is thought to be, in part, owing to earlier and increasingly competitive sports participation. Despite much speculation, the cause of both juvenile and adult osteochondritis dissecans remains unclear. Early recognition is essential. Whereas adult osteochondritis dissecans lesions have a greater propensity to instability, juvenile osteochondritis dissecans lesions are typically stable, and those with an intact articular surface have a potential to heal with nonoperative treatment through cessation of repetitive impact loading. The value of adjunctive immobilization, protected weightbearing, and unloader bracing has not been established. Skeletally immature patients with stable lesions that have not healed with nonoperative treatment should have consideration given to arthroscopic drilling to promote healing before the lesion progresses and requires more involved treatment with a less optimistic prognosis. Magnetic resonance imaging may allow early prediction of lesion healing potential. The majority of adult osteochondritis dissecans cases as well as those skeletally immature patients with unstable lesions and secondary loose bodies require fixation and possible bone grafting. Many unstable lesions will heal after stabilization, but long-term prognosis is not clear. Chronic loose fragments can be difficult to fix and have poor healing potential. Results of excision of large lesions from weightbearing zones are poor. Chondral resurfacing techniques have limited long-term data for cases of osteochondritis dissecans in skeletally immature patients.
Do You See What I See?
Authors: Rivadeneyra Rocío
Published: June 2006

The pervasiveness of harmful stereotypes about Latinos has led to concern over the effects of these on individuals. The mass media play a central role in perpetuating these stereotypes, yet we know very little about how Latinos perceive them. The purpose of this study was to examine how Latino adolescents view portrayals of Latino characters on Spanish- and English-language television programs. Thirty-seven Latino high school students participated in the questionnaire and focus group study. The adolescents were aware of the negative and stereotypical portrayals of Latinos presented on English-language television but considered Spanish-language television to present more balanced portrayals. Gender, immigrant generation, and regular television-viewing behaviors were all important factors that related to how the participants viewed the programs.
Identity, Conflict, and Coexistence
Authors: Hammack Phillip L.
Published: June 2006

Assuming a cultural psychology approach, this study examines the life stories of 30 Israeli and Palestinian adolescent participants in a coexistence program. Prior to participation, youth identity was characterized by polarization in which an ingroup ideology is internalized with little understanding of the outgroup’s ideological perspective. Three identity-related outcomes emerged following participation. Identity transcendence, in which a reduction in salience of ingroup ideology was accompanied by increased recognition of outgroup ideological legitimacy, characterized the most common immediate outcome. Identity accentuation characterized the long-term impact for most youth, whose ideological identifications ultimately conformed to an ingroup identity narrative. Identity conflict occurred among youth who struggled to integrate the experience of coexistence into the life story. Findings suggest (a) the challenges of identity intervention in the context of intractable conflict, and (b) a context-specific theory of identity in which polarized identities contribute to the reproduction and intractability of the conflict across generations.
Being in the Safety Zone
Authors: Everall Robin D. , Bostik Katherine E. , Paulson Barbara L.
Published: June 2006

This study examined how previously suicidal adolescents and emerging adults perceived their emotional experiences while being suicidal. Forty-one females and 9 males previously suicidal between the ages of 15 and 24 were interviewed. Qualitative data were analyzed using a grounded theory approach. Three major themes were identified in participants’ perceptions of their emotional experiences: (a) overwhelming despair, (b) shame and self-loathing, and (c) alienation and personal isolation. These emotional states were viewed within the multidimensional process of responding to emotions. Participants’ inability to deal with intense negative emotions appeared to be related to their suicidal state.
Dispelling Late-Night Myths
Authors: Young Dannagal G. , Tisinger Russell M.
Published: June 2006

This article explores two largely untested assumptions that dominate popular and scholarly examinations of the “late-night comedy audience.” The first assumption is that young people are tuning in to late-night comedy programs instead of the news. The second assumption is that there is one monolithic “late-night audience.” Using data from both the 2004 Pew Research Center Political Communications Study and the 2004 National Annenberg Election Survey, this article provides evidence that challenges these two assumptions, illustrating that young people are tuning in to late-night comedy in addition to—rather than in the place of—news and that the audiences of various late-night comedy programs have distinct sociodemographic and political profiles
Stealthy Wealth
Authors: Brophy-Baermann Michelle , Bloeser Andrew J.
Published: June 2006

A decade ago, the Personal Responsibility and Work Opportunity Reconciliation Act (PRWORA) ended welfare as we knew it. Since 1996, national media reports of the consequences of welfare reform have been decidedly positive. Yet a handful of journalists for metropolitan newspapers and the nonmainstream press have drawn attention to welfare-related scandals. These scandals have revolved around welfare privatization, an option PRWORA gave to the states. What could the public have known about privatization prior to reform? To answer this question, the authors investigate the elite debate over privatization and how the network news characterized this debate. They analyze the content of congressional testimony and news coverage by ABC, CBS, and NBC and conclude that the networks paid scant attention to privatization, and the coverage they did provide failed to accurately convey to viewers what postreform welfare administration might look like