bluuebunny/crossref_metadata_2025 huggingface dataset:
Differential Effect of Adenosine and Hypoxia on Potassium-Induced Dilation in the Isolated, Perfused Guinea Pig Heart
Authors: Young Mark A. , Merrill Gary F.
Published: September 2008

In 13 isolated, perfused guinea pig hearts we determined the coronary flow responses to abrupt elevation of perfusate potassium levels (final concentration 12–16 mM) in the absence and presence of adenosine, and during hypoxic perfusion. Control diastolic coronary flow and spontaneous heart rate averaged 7.85 ± 0.26 ml/min/g and 249.6 ± 2.4 beats/min, respectively. Potassium infusion (12–16 mM) in the absence of other intervention did not alter coronary flow significantly. Repeat potassium elevation in the presence of 0.05 and 0.1 µM adenosine (threshold dilating doses) produced respective flow increases of 58 and 43% above normokalemic flow (p < 0.05). Paradoxically, during hypoxic perfusion (70%, O2 or 45 % O2 in the gas phase) potassium did not elevate flow and, in some instances, constricted the vessels. Myocardial oxygen consumption and effluent potassium levels did not change with adenosine or hypoxic perfusion. These results suggest two points: (1) an interaction between potassium ion and adenosine may be important in the regulation of coronary flow and (2) hypoxic dilation in the coronary vasculature may act via a mechanism different from that of adenosine.
Early Microvascular Pathology during Hyperglycemia in Bats
Authors: Bohlen Glenn , Hankins Kimberly D.
Published: September 2008

The microvascular changes in the wing of bats, Myoitis lucifugus, were observed during 3 weeks of normal life and 5 weeks of streptozotocin induced hyperglycemia (300–400 mg/dl, plasma). During normal life, week-to-week variations in diameter and blood flow in the same set of vessels were minor. After hyperglycemia was induced, the major initial response was dilation of all microvessels except the smallest arterioles which constricted. The dilation phase was followed by progressive constriction of all vessels. Blood flow was near normal during the dilation phase, but flow gradually decreased as hyperglycemia continued and vasoconstriction occurred. The ability to repeatedly observe the same set of microvessels on a week-to-week basis and the absence of anesthesia may make the diabetic bat a useful model in which to study the early phases of microvascular pathology during chronic hyperglycemia, which begins abruptly in adult life. In addition, the sequence of microvascular changes during chronic hyperglycemia in the bat are qualitatively similar to those in other diabetic mammals, including man.
Circumferential Alignment of Muscle Cells in the Tunica media of the Human Brain Artery
Authors: Peters Mark W. , Canham Peter B. , Finlay Helen M.
Published: September 2008

Our purpose was to measure how structurally coordinated is the network of muscle cells in the brain artery. Vessels from 7 autopsies were fixed with glutaraldehyde and formalin at physiologic pressure. We embedded each artery alongside a block of liver, formed into a rectangular prism, prepared it for light microscopy and stained the sections with haematoxylin and eosin (HE). The angle of cutting the arterial segments was determined with the aid of the block of liver tissue as a Cartesian reference. We measured the directional alignment of vascular smooth muscle using the centrally located nucleus as a vector of orientation. The end coordinates of the profiles of the nuclei (appearing dark with the HE stain) were recorded on a digitizer tablet, and analysis was done as suggested by a previous modelling study. The method provides an average alignment from the collective measurements on the hundreds of nuclei in each histological section. Data from 10 arteries (approximately 22,000 nuclei) from 17 sections showed that brain arteries have highly oriented medial muscle cells aligned circumferentially (average magnitude of 1.3 ± [SD] 1.5 ° from true cross section), with a helical variation (along the artery) of ± 7.9 ° and a variation in the spiral direction of ± 5.4 °, i.e. a three-dimensional variation from nucleus to nucleus of ± 10 °.
Comparison of Blood Vessel Wall Dimensions in Normotensive and Hypertensive Rats by Histometric and Morphometric Methods
Authors: Lee Robert M.K.W. , Forrest J.B. , Garfield R.E. , Daniel E.E.
Published: September 2008

The histometric method is often used in hypertension studies in order to reconstruct, from cross-sectional profiles of vessels in the contracted state, a hypothetical relaxed state of the vessels based on the measured length of the internal elastic lamina (IEL). In this study, the accuracy of the histometric method was tested by comparing values obtained with the histometric method from contracted vessels versus values from morphometric measurements of vessels of the same calibre but maximally relaxed. Mesenteric arteries from spontaneously hypertensive and normotensive Wistar-Kyoto rats were used. We found that the lumen size of the vessels was dependent on the methods of measurement and preparation. Lumen size, determined with the histometric method from contracted vessels, tended to be underestimated mainly because the IEL became shortened during contraction of the vessels. When vessels were prepared by perfusion fixation, a high perfusion flow rate (7.6 ml/min) caused expansion of the lumen in muscular (lumen diameter 120–250 µm) and arteriolar vessels (40–100 µm), but not in the elastic arteries (400–700 µm). The cross-sectional area of the vessel wall, however, remained unchanged when the vessels were either contracted with norepinephrine or expanded with high transmural pressure, so morphometric measurements of the vessel wall and its components can be done on both contracted and relaxed vessels. Our results suggest that the use of the histometric method for the estimation of relaxed lumen size from the contracted vessels is of very limited value. We also suggest that, for an accurate comparison of vessel wall dimensions between hypertensive and ñormotensive animals, cross-sectional area should be used instead of wall thickness alone.
Neuraminidase and Contractile Responses to Norepinephrine in Rat Tail Artery
Authors: Rice James H. , Webb Clinton
Published: September 2008

Sialic acids are negatively charged groups in the carbohydrate side chains of glycolipids and glycoproteins which line the external membrane surface. The goal of this study was to characterize the effect of neuraminidase, which selectively cleaves sialic acids, on contractile activity in vascular smooth muscle. Helically cut strips of rat tail artery were mounted in an organ chamber and isometric contractions were recorded. Following treatment with neuraminidase (0.2 U/ml, 1 h), contractile responses to norepinephrine were significantly greater than control responses. Phasic contractions to norepinephrine in calcium-free medium were not altered by neuraminidase, whereas following calcium depletion with EGTA, contractile responses to added calcium were greater in enzyme-treated strips than in control when activated with norepinephrine. The augmentation of norepinephrine-induced contractions following neuraminidase treatment was reversed by incubation of the arterial strips with N-acetylneuraminic acid (10-4M). Neuraminidase had no effect on contractile responses to potassium chloride, angiotensin II, and caffeine. Biochemical assay indicated that approximately 63% of the total sialic acid residues were removed from the arterial strips during incubation with the enzyme. It is concluded that a component for the control of the transmembrane calcium movement in response to norepinephrine is dependent on the presence of sialic acid residues.
Comparison of Responses Elicited by Alpha-Thrombin in Isolated Canine Basilar, Coronary, Mesenteric, and Renal Arteries
Authors: White Richard P. , Shirasawa Yoshiaki , Robertson James T.
Published: September 2008

Alpha-thrombin was applied in cumulative concentrations of 0.001, 0.01, 0.1, 1.0, 10, and/or 100 U/ml to determine peak responses in isolated canine arterial rings. Alpha-thrombin failed to elicit contraction in the mesenteric artery, produced inconsistent effects in the renal artery, and produced biphasic effects (relaxation superseded by contraction) in the coronary and basilar arteries. In the basilar artery the relaxation induced by alpha-thrombin was blocked and the maximal contractions enhanced by reaming the vessel or by substituting heated thrombin for alpha-thrombin. The results support the hypotheses that alpha-thrombin acts on two distinct receptors in the basilar artery and that it is involved in the pathogenesis of cerebral vasospasm.
Characteristics of the Norepinephrine-Sensitive Ca2+ Store in Vascular Smooth Muscle
Authors: Saida Kooichi , van Breemen Cornelis
Published: September 2008

A comparison was made between the properties of the norepinephrine- and caffeine-sensitive Ca2+ store in both intact and skinned smooth muscle of the rabbit mesenteric artery. After a first application of 10-5M norepinephrine, reapplication of norepinephrine did not induce a second contraction in Ca2+-free medium. However, following this sequence 25 mM caffeine still induced a large contraction. The rates of Ca2+ leakage and Ca2+ filling of the norepinephrine-sensitive store were much faster than those of the caffeine-sensitive one. The amplitude of the norepinephrine-induced contraction in Ca2+-free medium also depended on the amount of Ca2+ present in the caffeine-sensitive store. In the saponin-treated skinned muscle caffeine induced a Ca2+ release only after loading with Ca2+, whereas norepinephrine was unable to induce Ca2+ release in the skinned preparation even after loading with Ca2+. The release of Ca2+ from the caffeine-sensitive store could be activated by Ca2+ itself when the skinned muscle was loaded with Ca2+ above 10-6M. These results suggest that the norepinephrine-sensitive Ca2+ store is distinct from a large fraction of the caffeine-sensitive one, and that the norepinephrine-sensitive store is close to the cell membrane. In vascular smooth muscle, under physiological conditions, Ca2+ released from the norepinephrine-sensitive store by norepinephrine may induce Ca2+ release from the caffeine-sensitive Ca2+ store which may be comprised of the sarcoplasmic reticulum.
Doubling Time of Carcinoembryonic Antigen Is a Significant Prognostic Factor after the Surgical Resection of Locally Recurrent Rectal Cancer
Authors: Tanaka Koji , Noura Shingo , Ohue Masayuki , Seki Yosuke , Yamada Terumasa , Miyashiro Isao , Ohigashi Hiroaki , Yano Masahiko , Ishikawa Osamu , Murata Kohei , Kameyama Masao , Imaoka Shingi
Published: September 2008

Background: Patients undergoing a curative rectal cancer resection have a risk of developing locoregional recurrence. A curative resection for local recurrence is the option of improvement in prognosis. However, a curative resection is sometimes too invasive and should be considered in selected patients. Methods: A total of 43 patients with locally recurrent rectal cancer who had been treated by operation between 1989 and 2007 were retrospectively reviewed and the factors, including doubling time of carcinoembryonic antigen (CEA-dt), were analyzed. Results: The 5-year overall survival rate after the operation for local recurrence was 50.8%. Gender, presence of distant metastasis, tumor size, CEA-dt and curability were found to be significant prognostic factors. A multivariate analysis demonstrated the presence of distant metastasis, CEA-dt and tumor size to be significant prognostic factors for overall survival. The 5-year overall survival rates of patients with a CEA-dt ≧150 days and a tumor size <5 cm were 76.9%. Conclusions: The tumor size and CEA-dt were useful prognostic factors that were recognizable before surgery. Patients with locally recurrent rectal cancer with a CEA-dt ≧150 days and a recurrent tumor size <5 cm are considered to be good candidates for surgery.
‘Padhar Regime’ – A Low-Dose Magnesium Sulphate Treatment for Eclampsia
Authors: Mahajan Niraj N. , Thomas Anita , Soni Rajani N. , Gaikwad Nilima L. , Jain Suchi M.
Published: September 2008

Aims: To determine the recurrent convulsion rate using low-dose magnesium sulphate regime in eclampsia and to identify toxicity and complications with clinical parameters. Methods: Prospective study with two different magnesium sulphate regimes in two slightly clinically different subgroups. Group A that came directly to our hospital and group B who had already received an injection of diazepam or Phenergan at the referring hospital. Group A received 10 g and group B 6 g loading dose of magnesium sulphate. Both groups received 4 g maintenance dose every 4 h. Results: Out of 95 eclamptic patients, only one woman in group B had recurrent convulsion. All women maintained normal respiratory rates. 39 (41.1%) women had absent knee jerks on at least one occasion when the maintenance dose was omitted. Urinary output was more than 30 ml/h in 92 (96.8%) women. In 5 women, maintenance dose had to be augmented to 5 g as reflexes were exaggerated. Conclusion: The low-dose regime appears to control and prevent convulsions effectively in Indian women. Clinical monitoring appears to be sufficient. We hope to be able to reassure health professionals at primary and secondary level hospitals about the safety of magnesium.
ADIDAC Trial: Analgesia with Dexibuprofen versus Ibuprofen in Patients Suffering from Primary Dysmenorrhea: A Crossover Trial
Authors: Kollenz C. , Phleps W. , Kaehler S.T.
Published: September 2008

Background: Primary dysmenorrhea is estimated to affect 40–50% of menstruating young women. Methods: Randomized, double-blind, 3-cycle crossover, active-controlled clinical trial conducted in 102 outpatients. Results: 102 patients entered the study and 77 were eligible for analyses. The mean (SD) age was 31.1 (7.0) years, and the mean cycle duration was 28.1 days (1.89) with a mean menstrual phase of 5.3 days (1.28). 40.26% of patients reported moderate pain from dysmenorrhea, and the remaining 59.74% reported severe pain. Compared to ibuprofen 400 mg, both dexibuprofen doses (200 and 300 mg) showed a trend towards superiority for sum of pain intensity difference (sum of PID), PID and total pain relief. Furthermore, dexibuprofen 200 mg had a faster onset of action compared to the double dose of ibuprofen (p = 0.035). A dose-effect relationship could be demonstrated for dexibuprofen in this visceral pain model. Tolerability was similar across all treatments. Conclusions: In patients experiencing acute visceral pain as a result of primary dysmenorrhea, dexibuprofen was associated with a dose-dependent effective analgesia; this effect was at least equivalent to that of the double dose of ibuprofen. With its lower body-loading dose, dexibuprofen expands the alternatives available to treat this condition.
Cell Surface Immobilization of GABAARs in Cerebellar Granule Cells Depends on the M3/M4 Cytoplasmatic Loop of the Alpha 1 Subunit
Authors: Perán Macarena , Hooper Helen , Marchal Juan A. , Boulaiz Houria , Rodríguez-Serrano Fernando , Velez Celia , Aránega Antonia , Salas Ramiro
Published: September 2008

γ-Aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the vertebrate brain. The localization of GABA receptors type A (GABAARs) at strategically located domains of the neuronal membrane is of vital importance for fast inhibitory synapse transmission efficacy. We have shown before that the lateral mobility of GABAARs depends on subunit composition of the complex. To study the lateral mobility of GABAARs in living, cultured neurons, we transfected cerebellar granule cells with either the complete α1 GABAAR subunit or with a truncation of the α1 subunit that lacks the major intracellular loop (M3/M4). We examined the location and lateral mobility of receptors containing both versions of the α1 subunit in living neurons. From fluorescence recovery after photobleaching experiments we present novel evidences that the intracellular M3/M4 loop of the α1 subunit restricts the lateral mobility of GABAARs when expressed in neurons. In addition, our immunocytochemical studies suggested that receptors containing the truncated subunit seem to be unable to reach synaptic localizations. Here we show for the first time that the α1 intracellular loop (M3/M4) domain has a relevant role in controlling the lateral mobility of GABAARs in neurons, and we believe that this is a novel and important contribution in neurobiology of GABAA receptors.
The Bovine Kidney as an Experimental Model in Urology: External Gross Anatomy
Authors: Carvalho Francismar S. , Bagetti Filho Hélio J.S. , Henry Robert W. , Pereira-Sampaio Marco A.
Published: September 2008

The objective of this work was to obtain and record detailed and accurate measurements of the bovine kidney and to compare these new data with findings in humans. Thirty-eight bovine kidneys were used. The total number of lobes, along with the number of lobes located in the cranial polar, caudal polar and hilar regions, were recorded. Several measurements of the kidneys were made and evaluated. The hilar region presents the greatest length (mean of 76.87 mm) of the 3 renal regions of the kidney. The large area of the bovine renal hilus could make access to hilar structures easier than in the human kidney. The coefficient of variation for renal length was small (8.14%), while the coefficient of variation for the lobar number was high (26.82%). The number of renal lobes ranged from 13 to 35, with a mean of 20.62. The hilar region presents the highest number of lobes, while the cranial pole presents the lowest. The number of lobes in the cranial and caudal poles increases with the width of these regions. This is different from the hilar region, in which the lobar number increases with the length of the hilus. These data indicate that the adult bovine kidney can be used as a model for certain urologic procedures, but researchers must be aware that there are some major differences between the adult bovine kidney and the human kidney, as indicated by the data reported in this paper.
Organ-Specific Changes in the Expression of Mannose-6-Phosphate Receptors during Postnatal Development in Rats
Authors: Jofré Guillermo F. , Balmaceda Valeria , Sartor Tirso , Carvelli Lorena , Barrera Patricia , Sosa Miguel A.
Published: September 2008

The significance of the coexistence of 2 mannose-6-phosphate receptors (MPRs) in most cell types still remains poorly understood. In this study, expression of the cation-dependent MPR (CD-MPR) and the cation-independent MPR (CI-MPR) was measured by Western blot in rat organs at 3 ages, i.e. in newborn and 10- and 90-day-old rats. It was observed that expression of the CI-MPR tends to diminish from newborns to adults in 5 of the 6 organs studied, whereas the CD-MPR did not show a clear tendency over time. In pancreas, conversely, both MPRs increased progressively from newborns to adults. The activity of 2 acid hydrolases was also measured at the different ages, and a low correlation was found with the expression of the 2 MPRs. With the exception of the pancreas, it is possible that the CI-MPR is mostly occupied with the clearance of insulin-like growth factor-II at early stages of development, and that later both MPRs may participate in the maturation of the lysosomal apparatus. We propose that in the pancreas, both receptors may be involved in increasing the proteolytic activity of this exocrine gland during postnatal development.
Recognizing Threat: A Simple Geometric Shape Activates Neural Circuitry for Threat Detection
Authors: Larson Christine L. , Aronoff Joel , Sarinopoulos Issidoros C. , Zhu David C.
Published: September 2008

The urgent need to recognize danger quickly has been shown to rely on preferential processing in dedicated neural circuitry. In previous behavioral studies examining the pattern of the face when displaying anger, we found evidence that simple noncontextual geometric shapes containing downward-pointing V-shaped angles activate the perception of threat. We here report that the neural circuitry known to be mobilized by many realistic, contextual threatening displays is also triggered by the simplest form of this V-shaped movement pattern, a downward-pointing triangle. Specifically, we show that simple geometric forms containing only downward-pointing V-shapes elicit greater activation of the amygdala, subgenual anterior cingulate cortex, superior temporal gyrus, and fusiform gyrus, as well as extrastriate visual regions, than do presentations of the identical V-shape pointing upward. Thus, this simple V-shape is capable of activating neural networks instantiating detection of threat and negative affect, suggesting that recognition of potential danger may be based, in part, on very simple, context-free visual cues.
Semantic Context and Visual Feature Effects in Object Naming: An fMRI Study using Arterial Spin Labeling
Authors: Hocking Julia , McMahon Katie L. , de Zubicaray Greig I.
Published: September 2008

Previous behavioral studies reported a robust effect of increased naming latencies when objects to be named were blocked within semantic category, compared to items blocked between category. This semantic context effect has been attributed to various mechanisms including inhibition or excitation of lexico-semantic representations and incremental learning of associations between semantic features and names, and is hypothesized to increase demands on verbal self-monitoring during speech production. Objects within categories also share many visual structural features, introducing a potential confound when interpreting the level at which the context effect might occur. Consistent with previous findings, we report a significant increase in response latencies when naming categorically related objects within blocks, an effect associated with increased perfusion fMRI signal bilaterally in the hippocampus and in the left middle to posterior superior temporal cortex. No perfusion changes were observed in the middle section of the left middle temporal cortex, a region associated with retrieval of lexical–semantic information in previous object naming studies. Although a manipulation of visual feature similarity did not influence naming latencies, we observed perfusion increases in the perirhinal cortex for naming objects with similar visual features that interacted with the semantic context in which objects were named. These results provide support for the view that the semantic context effect in object naming occurs due to an incremental learning mechanism, and involves increased demands on verbal self-monitoring.
Attending to Multiple Visual Streams: Interactions between Location-based and Category-based Attentional Selection
Authors: Fagioli Sabrina , Macaluso Emiliano
Published: September 2008

Behavioral studies indicate that subjects are able to divide attention between multiple streams of information at different locations. However, it is still unclear to what extent the observed costs reflect processes specifically associated with spatial attention, versus more general interference due the concurrent monitoring of multiple streams of stimuli. Here we used a factorial design to disentangle the correlates of location- versus category-based selection processes during fMRI. In all conditions, participants were presented with two overlapping visual stimuli (red shapes and green shapes) in each hemifield. In different blocks, subjects either: (1) attended to one single stimulus category, red shapes or green shapes, in one hemifield; (2) attended to both stimulus categories in the same hemifield; (3) attended to one single stimulus category, but monitoring both hemifields at the same time; or (4) attended to one stimulus category in one hemifield, and the other category in the opposite hemifield. The behavioral data showed the expected costs of dividing spatial attention across the two hemifields, and the cost of monitoring two stimulus categories versus one category. The imaging data revealed activation of a dorsal fronto-parietal network, both for dividing spatial attention and for monitoring multiple stimulus categories. However, unlike behavioral data, the imaging results also showed a significant interaction between location- and category-based attention within the same network. This demonstrates that the fronto-parietal cortex engages in both of these selective attention functions, and that a mere increase in task difficulty cannot explain colocalization of these processes. We conclude that, under conditions of multiple streams monitoring, fronto-parietal regions control location- and category-based attentional selection.
Development during Adolescence of the Neural Processing of Social Emotion
Authors: Burnett Stephanie , Bird Geoffrey , Moll Jorge , Frith Chris , Blakemore Sarah-Jayne
Published: September 2008

In this fMRI study, we investigated the development between adolescence and adulthood of the neural processing of social emotions. Unlike basic emotions (such as disgust and fear), social emotions (such as guilt and embarrassment) require the representation of another's mental states. Nineteen adolescents (10–18 years) and 10 adults (22–32 years) were scanned while thinking about scenarios featuring either social or basic emotions. In both age groups, the anterior rostral medial prefrontal cortex (MPFC) was activated during social versus basic emotion. However, adolescents activated a lateral part of the MPFC for social versus basic emotions, whereas adults did not. Relative to adolescents, adults showed higher activity in the left temporal pole for social versus basic emotions. These results show that, although the MPFC is activated during social emotion in both adults and adolescents, adolescents recruit anterior (MPFC) regions more than do adults, and adults recruit posterior (temporal) regions more than do adolescents.
Neural Correlates of Metamemory: A Comparison of Feeling-of-Knowing and Retrospective Confidence Judgments
Authors: Chua Elizabeth F. , Schacter Daniel L. , Sperling Reisa A.
Published: September 2008

Metamemory refers to knowledge and monitoring of one's own memory. Metamemory monitoring can be done prospectively with respect to subsequent memory retrieval or retrospectively with respect to previous memory retrieval. In this study, we used fMRI to compare neural activity during prospective feeling-of-knowing and retrospective confidence tasks in order to examine common and distinct mechanisms supporting multiple forms of metamemory monitoring. Both metamemory tasks, compared to non-metamemory tasks, were associated with greater activity in medial prefrontal, medial parietal, and lateral parietal regions, which have previously been implicated in internally directed cognition. Furthermore, compared to non-metamemory tasks, metamemory tasks were associated with less activity in occipital regions, and in lateral inferior frontal and dorsal medial prefrontal regions, which have previously shown involvement in visual processing and stimulus-oriented attention, respectively. Thus, neural activity related to metamemory is characterized by both a shift toward internally directed cognition and away from externally directed cognition. Several regions demonstrated differences in neural activity between feeling-of-knowing and confidence tasks, including fusiform, medial temporal lobe, and medial parietal regions; furthermore, these regions also showed interaction effects between task and the subjective metamemory rating, suggesting that they are sensitive to the information monitored in each particular task. These findings demonstrate both common and distinct neural mechanisms supporting metamemory processes and also serve to elucidate the functional roles of previously characterized brain networks.
Theta Phase Synchrony and Conscious Target Perception: Impact of Intensive Mental Training
Authors: Slagter Heleen A. , Lutz Antoine , Greischar Lawrence L. , Nieuwenhuis Sander , Davidson Richard J.
Published: September 2008

The information processing capacity of the human mind is limited, as is evidenced by the attentional blink—a deficit in identifying the second of two targets (T1 and T2) presented in close succession. This deficit is thought to result from an overinvestment of limited resources in T1 processing. We previously reported that intensive mental training in a style of meditation aimed at reducing elaborate object processing, reduced brain resource allocation to T1, and improved T2 accuracy [Slagter, H. A., Lutz, A., Greischar, L. L., Francis, A. D., Nieuwenhuis, S., Davis, J., et al. Mental training affects distribution of limited brain resources. PloS Biology, 5, e138, 2007]. Here we report EEG spectral analyses to examine the possibility that this reduction in elaborate T1 processing rendered the system more available to process new target information, as indexed by T2-locked phase variability. Intensive mental training was associated with decreased cross-trial variability in the phase of oscillatory theta activity after successfully detected T2s, in particular, for those individuals who showed the greatest reduction in brain resource allocation to T1. These data implicate theta phase locking in conscious target perception, and suggest that after mental training the cognitive system is more rapidly available to process new target information. Mental training was not associated with changes in the amplitude of T2-induced responses or oscillatory activity before task onset. In combination, these findings illustrate the usefulness of systematic mental training in the study of the human mind by revealing the neural mechanisms that enable the brain to successfully represent target information.
Age-related Alterations in Simple Declarative Memory and the Effect of Negative Stimulus Valence
Authors: Murty Vishnu P. , Sambataro Fabio , Das Saumitra , Tan Hao-Yang , Callicott Joseph H. , Goldberg Terry E. , Meyer-Lindenberg Andreas , Weinberger Daniel R. , Mattay Venkata S.
Published: September 2008

Healthy aging has been shown to modulate the neural circuitry underlying simple declarative memory; however, the functional impact of negative stimulus valence on these changes has not been fully investigated. Using BOLD fMRI, we explored the effects of aging on behavioral performance, neural activity, and functional coupling during the encoding and retrieval of novel aversive and neutral scenes. Behaviorally, there was a main effect of valence with better recognition performance for aversive greater than neutral stimuli in both age groups. There was also a main effect of age with better recognition performance in younger participants compared to older participants. At the imaging level, there was a main effect of valence with increased activity in the medial-temporal lobe (amygdala and hippocampus) during both encoding and retrieval of aversive relative to neutral stimuli. There was also a main effect of age with older participants showing decreased engagement of medial-temporal lobe structures and increased engagement of prefrontal structures during both encoding and retrieval sessions. Interestingly, older participants presented with relatively decreased amygdalar–hippocampal coupling and increased amygdalar–prefrontal coupling when compared to younger participants. Furthermore, older participants showed increased activation in prefrontal cortices and decreased activation in the amygdala when contrasting the retrieval of aversive and neutral scenes. These results suggest that although normal aging is associated with a decline in declarative memory with alterations in the neural activity and connectivity of brain regions underlying simple declarative memory, memory for aversive stimuli is relatively better preserved than for neutral stimuli, possibly through greater compensatory prefrontal cortical activity.
Neural Priming in Human Frontal Cortex: Multiple Forms of Learning Reduce Demands on the Prefrontal Executive System
Authors: Race Elizabeth A. , Shanker Shanti , Wagner Anthony D.
Published: September 2008

Past experience is hypothesized to reduce computational demands in PFC by providing bottom–up predictive information that informs subsequent stimulus-action mapping. The present fMRI study measured cortical activity reductions (“neural priming”/“repetition suppression”) during repeated stimulus classification to investigate the mechanisms through which learning from the past decreases demands on the prefrontal executive system. Manipulation of learning at three levels of representation—stimulus, decision, and response—revealed dissociable neural priming effects in distinct frontotemporal regions, supporting a multiprocess model of neural priming. Critically, three distinct patterns of neural priming were identified in lateral frontal cortex, indicating that frontal computational demands are reduced by three forms of learning: (a) cortical tuning of stimulus-specific representations, (b) retrieval of learned stimulus-decision mappings, and (c) retrieval of learned stimulus-response mappings. The topographic distribution of these neural priming effects suggests a rostrocaudal organization of executive function in lateral frontal cortex.
Concurrent Sound Segregation Is Enhanced in Musicians
Authors: Zendel Benjamin Rich , Alain Claude
Published: September 2008

The ability to segregate simultaneously occurring sounds is fundamental to auditory perception. Many studies have shown that musicians have enhanced auditory perceptual abilities; however, the impact of musical expertise on segregating concurrently occurring sounds is unknown. Therefore, we examined whether long-term musical training can improve listeners' ability to segregate sounds that occur simultaneously. Participants were presented with complex sounds that had either all harmonics in tune or the second harmonic mistuned by 1%, 2%, 4%, 8%, or 16% of its original value. The likelihood of hearing two sounds simultaneously increased with mistuning, and this effect was greater in musicians than nonmusicians. The segregation of the mistuned harmonic from the harmonic series was paralleled by an object-related negativity that was larger and peaked earlier in musicians. It also coincided with a late positive wave referred to as the P400 whose amplitude was larger in musicians than in nonmusicians. The behavioral and electrophysiological effects of musical expertise were specific to processing the mistuned harmonic as the N1, the N1c, and the P2 waves elicited by the tuned stimuli were comparable in both musicians and nonmusicians. These results demonstrate that listeners' ability to segregate concurrent sounds based on harmonicity is modulated by experience and provides a basis for further studies assessing the potential rehabilitative effects of musical training on solving complex scene analysis problems illustrated by the cocktail party example.
Modality- and Task-specific Brain Regions Involved in Chinese Lexical Processing
Authors: Liu Li , Deng Xiaoxiang , Peng Danling , Cao Fan , Ding Guosheng , Jin Zhen , Zeng Yawei , Li Ke , Zhu Lei , Fan Ning , Deng Yuan , Bolger Donald J. , Booth James R.
Published: September 2008

fMRI was used to examine lexical processing in native adult Chinese speakers. A 2 task (semantics and phonology) × 2 modality (visual and auditory) within-subject design was adopted. The semantic task involved a meaning association judgment and the phonological task involved a rhyming judgment to two sequentially presented words. The overall effect across tasks and modalities was used to identify seven ROIs, including the left fusiform gyrus (FG), the left superior temporal gyrus (STG), the left ventral inferior frontal gyrus (VIFG), the left middle temporal gyrus (MTG), the left dorsal inferior frontal gyrus (DIFG), the left inferior parietal lobule (IPL), and the left middle frontal gyrus (MFG). ROI analyses revealed two modality-specific areas, FG for visual and STG for auditory, and three task-specific areas, IPL and DIFG for phonology and VIFG for semantics. Greater DIFG activation was associated with conflicting tonal information between words for the auditory rhyming task, suggesting this region's role in strategic phonological processing, and greater VIFG activation was correlated with lower association between words for both the auditory and the visual meaning task, suggesting this region's role in retrieval and selection of semantic representations. The modality- and task-specific effects in Chinese revealed by this study are similar to those found in alphabetical languages. Unlike English, we found that MFG was both modality- and task-specific, suggesting that MFG may be responsible for the visuospatial analysis of Chinese characters and orthography-to-phonology integration at a syllabic level.
Evaluation of WRF Forecasts of Tornadic and Nontornadic Outbreaks When Initialized with Synoptic-Scale Input
Authors: Shafer Chad M. , Mercer Andrew E. , Doswell Charles A. , Richman Michael B. , Leslie Lance M.
Published: September 2008

Uncertainty exists concerning the links between synoptic-scale processes and tornado outbreaks. With continuously improving computer technology, a large number of high-resolution model simulations can be conducted to study these outbreaks to the storm scale, to determine the degree to which synoptic-scale processes appear to influence the occurrence of tornado outbreaks, and to determine how far in advance these processes are important. To this end, 50 tornado outbreak simulations are compared with 50 primarily nontornadic outbreak simulations initialized with synoptic-scale input using the Weather Research and Forecasting (WRF) mesoscale model to determine if the model is able to distinguish the outbreak type 1, 2, and 3 days in advance of the event. The model simulations cannot resolve tornadoes explicitly; thus, the use of meteorological covariates (in the form of numerous severe-weather parameters) is necessary to determine whether or not the model is predicting a tornado outbreak. Results indicate that, using the covariates, the WRF model can discriminate outbreak type consistently at least up to 3 days in advance. The severe-weather parameters that are most helpful in discriminating between outbreak types include low-level and deep-layer shear variables and the lifting condensation level. An analysis of the spatial structures and temporal evolution, as well as the magnitudes, of the severe-weather parameters is critical to diagnose the outbreak type correctly. Thermodynamic instability parameters are not helpful in distinguishing the outbreak type, primarily because of a strong seasonal dependence and convective modification in the simulations.
Experimental Dynamical Seasonal Forecasts of Tropical Cyclone Activity at IRI
Authors: Camargo Suzana J. , Barnston Anthony G.
Published: September 2008

The International Research Institute for Climate and Society (IRI) has been issuing experimental seasonal tropical cyclone activity forecasts for several ocean basins since early 2003. In this paper the method used to obtain these forecasts is described and the forecast performance is evaluated. The forecasts are based on tropical cyclone–like features detected and tracked in a low-resolution climate model, namely ECHAM4.5. The simulation skill of the model using historical observed sea surface temperatures (SSTs) over several decades, as well as with SST anomalies persisted from the previous month’s observations, is discussed. These simulation skills are compared with skills of purely statistically based hindcasts using as predictors recently observed SSTs. For the recent 6-yr period during which real-time forecasts have been made, the skill of the raw model output is compared with that of the subjectively modified probabilistic forecasts actually issued.

Despite variations from one basin to another, the levels of hindcast skill for the dynamical and statistical forecast approaches are found, overall, to be approximately equivalent at fairly modest but statistically significant levels. The dynamical forecasts require statistical postprossessing (calibration) to be competitive with, and in some circumstances superior to, the statistical models. Skill levels decrease only slowly with increasing lead time up to 2–3 months. During the recent period of real-time forecasts, the issued forecasts have had higher probabilistic skill than the raw model output, due to the forecasters’ subjective elimination of the “overconfidence” bias in the model’s forecasts. Prospects for the future improvement of dynamical tropical cyclone prediction are considered.
A New Diffusion Scheme for Numerical Models Based on Full Irreversibility
Authors: Liu C. , Liu Y. , Xu H.
Published: September 2008

In this work, the forecast accuracy of a numerical weather prediction model is improved by emulating physical dissipation as suggested by the second law of thermodynamics, which controls the irreversible evolutionary direction of a many-body system like the atmosphere. The ability of the new physics-based scheme to improve model accuracy is demonstrated via the case of the one-dimensional viscous Burgers equation and the one-dimensional diffusion equation, as well as a series of numerical simulations of the well-known 1998 successive torrential rains along the Yangtze River valley and 365 continuous 24-h simulations during 2005–06 with decreased root-mean-square errors and improved forecasts in all of the simulations.
Public sector benchmarking: a survey of scientific articles, 1990—2005
Authors: Braadbaart Okke , Yusnandarshah Benni
Published: September 2008

This article assesses the past 15 years' evolution of Public Sector Benchmarking (PSB) research. We do so with a database of 147 peer-reviewed articles published between 1990 and 2005. Over this period PSB evolved into a mature and strongly international field of research. A theoretical and conceptual rift runs through the literature, with those advocating PSB as a tool for managed competition on one side, and those promoting benchmarking as a voluntary and collaborative learning process on the other. A first challenge facing future PSB researchers is that of closing the gap between the managed and voluntary benchmarking perspectives; a second challenge concerns empirical tests that capture the effects of different benchmarking regimes on the performance of public sector providers.

Points for practitioners Benchmarking is widely advocated as a tool for enhancing the performance of public sector providers. This article reviews the academic literature on benchmarking. This literature suggests that public sector benchmarking can fulfill its promise if only policy-makers pay sufficient attention to benchmarking design, particularly the development of appropriate accounting systems and the balancing of collaborative and competitive elements. Dos and don'ts for PSB innovators are discussed in the concluding section. An extensive reference list is appended to the article.
Supreme Audit Institutions and their communication strategies
Authors: González Belén , López Antonio , García Roberto
Published: September 2008

In the past, Supreme Audit Institutions (SAIs) rarely publicized their work. In the 1990s, a few began to publish booklets and brochures for popular consumption and to establish ties with the media. These days, SAIs are concerned about communication. A communication policy completes their cycle of accountability, justifies their existence, is an essential component of their independence and efficiency and brings about measures which assess the impact of their work.The aim of this article is to analyse the latest communication strategies developed by SAIs in order to publicize the results of their activity and to provide the public with an overall vision of what they do. The study, based on a questionnaire sent out to European Union SAIs, highlights the fact that these bodies undertake wide-ranging communication activities involving a close relationship with the media and the use of Internet websites.

Points for practitioners This article explores the most recent developments in European Union SAI communication strategy. Based on survey research, the study concludes that SAIs maintain a close relationship with the media and have been able to take advantage of the opportunity offered by the Internet to publish their results and to provide users with an overview of their work. For SAIs, this analysis allows them to be graded in terms of their relationship with the media and how they use Internet websites. Hence it will be possible to establish criteria leading to improvements or maintenance of their relative situation.
Women and family-friendly policies in the Korean government
Authors: Kim Sangmook
Published: September 2008

This paper discusses the desires and realities of women and family-friendly policies in the Korean government. The implementation of policies for gender equality during the past two decades has increased the ratio of women in the civil service. As the number of women in the government has increased, family-friendly policies have been provided for civil servants to balance work and personal life. Family-friendly policies are expected to positively affect the civil servants and government performance. However, the family-friendly policies are not effectively implemented because they are not properly bundled, and civil servants are reluctant to take advantage of these policies under male-centered organizational practices. To aid civil servants in balancing the role requirements of work and family, government organizations should create family-friendly work environments by not only instituting various proper family-friendly programs but also by promoting a supportive culture. Several efforts for establishing such a supportive culture are suggested.

Points for practitioners To aid civil servants in balancing the role requirements of work and family, government organizations should create family-friendly work environments by instituting various family-friendly programs and by promoting supportive work—family culture. Only providing family-friendly programs without promoting cultural change is insufficient. Several efforts are essential to establish a supportive work—family culture. First of all, the organizational leaders should be aware of the positive effects of family-friendly programs on employees' attitude and behavior and organizational performance. They need to make civil servants believe that their careers will not be negatively affected by using family-friendly benefits through providing them with counseling and education on family-friendly programs and work—life balance. They should also make every effort to reduce the male-centered organizational practices and to support the work—family concerns of the civil servants.
A cultural ecology of New Public Management
Authors: Pillay Soma
Published: September 2008

During the 1980s, new public management (NPM) evolved as a universal model of reform and governance in public sector management. However, in practice, there have been significant differences between countries that have been successful in NPM reform and those that have not. Drawing on institutional theory and frameworks of national culture, this article is aimed at exploring the applicability of NPM in a particular cultural context. In particular, the study analyses the applicability of NPM in the developing economy of South Africa. Using Hofstede's construct of national culture and institutional theory, social units within South Africa are explained. A cultural theory is presented whereby NPM is depicted as a culturally dependent strategy. The present study proposes a cultural theory that takes into account the differences that exist among the cultures of various countries. It is suggested that the successful implementation of NPM requires complementarities between the reform strategies that are adopted and the particular cultural characteristics of the country in which they are implemented.

Points for practitioners This article is useful to practitioners in attempting to understand the importance of congruence between reform strategies and practices and national culture. In particular, the study makes a contribution to policy entrepreneurship in recognizing that efficiency and institutional perspectives must be complementary and congruent if success in reform is to be achieved.