bluuebunny/crossref_metadata_2025 huggingface dataset:
Should the Brain Be Regarded as a Computer?
Authors: Spiegel E.A.
Published: March 2007

In recent years analogies between thinking processes and computer mechanisms have been pointed out. There exist, however, also considerable differences between higher cerebral activities and computers. It seems, therefore, hazardous to consider the human brain exclusively as a computer.
Stereotactic Systems and Procedures for Depth Electrode Placement: Technical Aspects
Authors: Olivier André , Bertrand Gilles , Peters Terry
Published: March 2007

The authors describe the conversion of the Leksell spherical system to that of the orthogonal approach for depth electrode placement, by the addition of relatively simple devices to the main frame. These modifications have created the need for new instrumentation such as teleradiology with laser beam centering and the use of an all-purpose stereotactic chair. The main device used for the orthogonal approach is an instrument and electrode carrier moving on sliding side bars. This system can also take advantage of the newer imaging techniques, such as CT scanning, digital angiography and NMR, by the addition of computer markers which are interchangeable with the frame side bars.
Multipolar Hollow-Core Electrode for Brain Recordings
Authors: Comte P. , Siegfried J. , Wieser H.G.
Published: March 2007

A multicontact macroelectrode for brain recordings is described. lts hollow-core structure and slightly recessed contacts allow the electrode to be guided with a central stylet for minimal tissue trauma. The helical design of the electrode is characterized by high fatigue resistance and high flexibility allowing movement with the brain and preventing slicing through tissue. Clinical results have been obtained on epileptic patients.
What Happened to VIM Thalamotomy for Parkinson's Disease?
Authors: Tasker R.R. , Siqueira J. , Hawrylyshyn P. , Organ L.W.
Published: March 2007

A prospective review of 75 of 190 parkinsonian patients undergoing unilateral thalamotomy was displayed with a computer graphics technique examining three equal consecutive groups from the pre-, early, and late L-dopa eras. Histograms for average function and scattergrams of individual patient''s performance preoperatively and up to 2 years postoperatively were prepared. No ipsilateral effects or consistent iatrogenic deterioration of any function were identified. 2 years after surgery, 82% had no tremor in the contralateral fingers or hand and 7% had almost no tremor; contralateral tremor elsewhere was infrequent. Rigidity and manual dexterity improved less strikingly, the latter only reflecting abolition of tremor; locomotion, speech, facial movement and handwriting did not improve. There was no mortality, but 8% had persistent significant complications. VIM thalamotomy remains the treatment of choice for severe drug-resistant parkinsonian tremor.
Neurophysiological Assessment of Electrode Placement in the Spinal Cord
Authors: Halter J. , Dolenc V. , Dimitrijevic M.R. , Sharkey P.C.
Published: March 2007

The use of neurophysiological techniques in addition to radiographic methods to determine the location of electrodes to be introduced into the epidural space for spinal cord stimulation is beneficial. Information on the distribution of paresthesias and muscle twitches provides an indication of the level and lateral location in relation to the midline of the spinal cord. For electrodes placed posteriorly, the threshold currents necessary for sensation are lower than those for muscle responses. Somatosensory evoked potentials resulting from epidural stimulation demonstrate effective depolarization of ascending structures. Evoked potentials recorded from the electrodes in response to peripheral nerve or spinal cord stimulation at a distant segment illustrate the possibility of activation of underlying generators of the spinal cord.
Percutaneous Radiofrequency Spinal Rhizotomy
Authors: Pagura Jorge Roberto
Published: March 2007

An anatomical study was conducted to evaluate the emergence of spinal roots at different levels and their relation to the intervertebral foramena. A percutaneous needie was thernnserted in the direction of these roots and their contact studied under direct vision and by X-rays. These results were compared with those obtained in 50 patients who underwent spinal rhizotomies. There is a direct correlation between the anatomy at different levels and the quality of relief obtained after surgery.
Stereotactic CT Scanning for the Biopsy of Intracranial Lesions and Functional Neurosurgery
Authors: Kelly Patrick J. , Kall Bruce , Goerss Stephan
Published: March 2007

This report describes a system for incorporation of stereotactic CT scanning data, stereotactic arteriographic data and a computer-generated stereotactic atlas into a three-dimensional matrix utilizing an operating room computer. 86 patients have undergone computer-assisted stereotactic biopsies of intracranial lesions without mortality or neurologie morbidity. Neuroablative and neuroaugmentative procedures have been performed on 5 patients using the CT stereotactic atlas with good correlation with target points determined by ventriculography and microelectrode recording.
Computer Graphics with Computerized Tomography for Functional Neurosurgery
Authors: Hardy Tyrone L. , Koch Jay , Lassiter Anthony
Published: March 2007

A computer graphics technique for computer-assisted stereotactic surgery is presented. The program is designed to aid the surgeon by presenting an on-line graphics display of stereotactic probes and electrodes superimposed on cross sections of the human brain stem. This technique simulates an otherwise blind surgical procedure on a graphics screen for use during surgery. An earlier system based around the DEC MINC-11 BA computer system has been used by the authors for the performance of stereotactic surgery with convehtional ventriculography. This system has been upgraded and is now configured about an even more compact microprocessor-based hardware system with expanded graphics capabilities, which also allows its use with computerized tomography.
A GABA-EEG Test of the Blood-Brain Barrier near Epileptic Foci
Authors: Remler Michael P. , Marcussen William H.
Published: March 2007

The permeability of the blood-brain barrier (BBB) to y-aminobutyric acid (GABA) in the region of an epileptic focus may be assessed by infusing GABA and measuring a change in epileptic spike activity on the EEG. GABA does not cross the normal BBB but will suppress epileptic spike activity when it does cross where the BBB is damaged. 9 alumina-cobalt experimental epileptic foci were all initially suppressible, but 7 then became unsuppressible. When the foci were irradiated to lower the BBB, all 7 be-came temporarily suppressible. The experiments demonstrate that (1) epileptic foci can be equally active both with the BBB ''open'' and ''closed''; (2) the intravenous GABA-EEG test can detect whether the BBB near the epileptic focus is open to GABA, and (3) anatomie tests of BBB integrity (in these experiments intravenous trypan blue) cannot deter-mine if whether BBB near the focus is ''open'' to GABA. Since the intravenous GABA-EEG test reveals the permeability of the BBB in the immediate environment of the epileptic focus, it may be very useful in the selection of a susceptible therapeutic group for inhibitory amino acid therapy.
Decreased Obesity and Atherosclerosis in Human Paraoxonase 3 Transgenic Mice
Authors: Shih Diana M. , Xia Yu-Rong , Wang Xu-Ping , Wang Susanna S. , Bourquard Noam , Fogelman Alan M. , Lusis Aldons J. , Reddy Srinivasa T.
Published: March 2007

Paraoxonase 3 (PON3) is a member of the PON family, which includes PON1, PON2, and PON3. Recently, PON3 was shown to prevent the oxidation of low-density lipoprotein in vitro. To test the role of PON3 in atherosclerosis and related traits, 2 independent lines of human PON3 transgenic (Tg) mice on the C57BL/6J (B6) background were constructed. Human PON3 mRNA was detected in various tissues, including liver, lung, kidney, brain, adipose, and aorta, of both lines of Tg mice. The human PON3 mRNA levels in the livers of PON3 Tg mice were 4- to 7-fold higher as compared with the endogenous mouse Pon3 mRNA levels. Human PON3 protein and activity were detected in the livers of Tg mice as well. No significant differences in plasma total, high-density lipoprotein, and very-low-density lipoprotein/low-density lipoprotein cholesterol and triglyceride and glucose levels were observed between the PON3 Tg and non-Tg mice. Interestingly, atherosclerotic lesion areas were significantly smaller in both lines of male PON3 Tg mice as compared with the male non-Tg littermates on B6 background fed an atherogenic diet. When bred onto the low-density lipoprotein receptor knockout mouse background, the male PON3 Tg mice also exhibited decreased atherosclerotic lesion areas and decreased expression of monocyte chemoattractant protein-1 in the aorta as compared with the male non-Tg littermates. In addition, decreased adiposity and lower circulating leptin levels were observed in both lines of male PON3 Tg mice as compared with the male non-Tg mice. In an F2 cross, adipose Pon3 mRNA levels inversely correlated with adiposity and related traits. Our study demonstrates that elevated PON3 expression significantly decreases atherosclerotic lesion formation and adiposity in male mice. PON3 may play an important role in protection against obesity and atherosclerosis.
Fluvastatin Alters Platelet Aggregability in Patients With Hypercholesterolemia
Authors: Haramaki Nobuya , Ikeda Hisao , Takenaka Katsuhiko , Katoh Atsushi , Sugano Ryo , Yamagishi Sho-ichi , Matsuoka Hidehiro , Imaizumi Tsutomu
Published: March 2007

Background—

Hypercholesterolemia enhances platelet aggregability. Statins have beneficial effects on cardiovascular events. The purpose of this study is to investigate whether statins inhibit platelet aggregation and, if so, the mechanisms.

Methods and Results—

Twelve patients with hypercholesterolemia were prospectively randomized in a crossover design to receive either fluvastatin (20 mg/d) or colestimide (3000 mg/d) for 12 weeks. The subjects were switched to the opposite arm for additional 12 weeks. Before and after first and second treatments, experiments were performed. Eleven age-matched volunteers with normal lipid profiles served as controls. ADP-induced platelet aggregation, platelet-derive nitric oxide (PDNO) release, intraplatelet levels of GSH and GSSG, and intraplatelet nitrotyrosine production during platelet aggregation were measured. Fluvastatin and colestimide equally lowered total and low density lipoprotein cholesterol levels in hypercholesterolemia. Platelet aggregation was greater in hypercholesterolemia than in normocholesterolemia before treatment and was altered by fluvastatin. PDNO release, intraplatelet glutathione level, and GSH/GSSG ratio were lower in hypercholesterolemia than in normocholesterolemia before treatment and were increased by fluvastatin. Intraplatelet nitrotyrosine formation was greater in hypercholesterolemia than in normocholesterolemia, and decreased by fluvastatin. Colestimide did not have such effects. In vitro application of fluvastatin dose-dependently inhibited platelet aggregation. Furthermore, in vitro application of fluvastatin dose-dependently inhibited platelet nitrotyrosine expressions and the inhibitory effects by fluvastatin were reversed by preincubation with geranylgeranylpyrophosphate.

Conclusions—

Fluvastatin altered platelet aggregability in hypercholesterolemic patients in a cholesterol-lowering independent manner, which was partly mediated by the improvement of intraplatelet redox imbalance.
High-Density Lipoprotein Modulates Oxidized Phospholipid Signaling in Human Endothelial Cells From Proinflammatory to Anti-inflammatory
Authors: Gharavi Nima M. , Gargalovic Peter S. , Chang Irene , Araujo Jesus A. , Clark Michael J. , Szeto Wan Lam , Watson Andrew D. , Lusis Aldons J. , Berliner Judith A.
Published: March 2007

Objective—

Oxidized 1-palmitoyl-2-arachidonyl-
sn
-3-glycero-phosphorylcholine (Ox-PAPC) and its component phospholipid, 1-palmitoyl-2-(5,6 epoxyisoprostanoyl)-
sn
-glycero-3-phosphocholine (PEIPC), which are present in atherosclerotic lesions, activate endothelial cells to induce a complex inflammatory and pro-oxidant response. Previously, we demonstrated induction of genes regulating chemotaxis, sterol biosynthesis, the unfolded protein response, and redox homeostasis by Ox-PAPC in human aortic endothelial cells (HAECs). Activation of the
c-Src
kinase/signal transducer and activator of transcription 3 and the endothelial nitric oxide synthase/sterol regulatory element binding protein (SREBP) pathways were shown to regulate several of these inflammatory effects of Ox-PAPC in HAECs. The goal of the current studies was to determine the role of high-density lipoprotein (HDL) in regulating Ox-PAPC signaling in HAECs.

Methods and Results—

Using quantitative real-time polymerase chain reaction, Western analysis, and functional studies, we demonstrated that pretreatment of HAECs with HDL reduced the induction of inflammatory, sterol biosynthetic, and unfolded protein response genes by Ox-PAPC and PEIPC; Ox-PAPC-induced chemotactic activity and monocyte binding were also decreased. These effects were associated with HDL inhibition of Ox-PAPC-induced
c-Src
, signal transducer and activator of transcription 3, and SREBP activation, alterations in endothelial nitric oxide synthase phosphorylation (previously associated with the inflammatory action of Ox-PAPC), and a decrease in superoxide formation. Finally, we demonstrated that treatment with HDL did not inhibit Ox-PAPC and PEIPC-induced activation of redox pathways, which protect the cell from the effects of oxidative stress.

Conclusions—

Taken together, these studies demonstrated that HDL inhibits the pro-inflammatory effects of Ox-PAPC and PEIPC, while maintaining the antioxidant activities of these lipids.
Platelets Recruit Human Dendritic Cells Via Mac-1/JAM-C Interaction and Modulate Dendritic Cell Function In Vitro
Authors: Langer Harald F. , Daub Karin , Braun Gregor , Schönberger Tanja , May Andreas E. , Schaller Martin , Stein Gerburg M. , Stellos Konstantinos , Bueltmann Andreas , Siegel-Axel Dorothea , Wendel Hans P. , Aebert Hermann , Roecken Martin , Seizer Peter , Santoso Sentot , Wesselborg Sebastian , Brossart Peter , Gawaz Meinrad
Published: March 2007

Objective—

Thrombotic events and immunoinflammatory processes take place next to each other during vascular remodeling in atherosclerotic lesions. In this study we investigated the interaction of platelets with dendritic cells (DCs).

Methods and Results—

The rolling of DCs on platelets was mediated by PSGL-1. Firm adhesion of DCs was mediated through integrin α
M
β
2
(Mac-1). In vivo, adhesion of DCs to injured carotid arteries in mice was mediated by platelets. Pretreatment with soluble GPVI, which inhibits platelet adhesion to collagen, substantially reduced recruitment of DCs to the injured vessel wall. In addition, preincubation of DCs with sJAM-C significantly reduced their adhesion to platelets. Coincubation of DCs with platelets induced maturation of DCs, as shown by enhanced expression of CD83. In the presence of platelets, DC-induced lymphocyte proliferation was significantly enhanced. Moreover, coincubation of DCs with platelets resulted in platelet phagocytosis by DCs, as verified by different cell phagocytosis assays. Finally, platelet/DC interaction resulted in apoptosis of DCs mediated by a JAM-C–dependent mechanism.

Conclusions—

Recruitment of DCs by platelets, which is mediated via CD11b/CD18 (Mac-1) and platelet JAM-C, leads to DC activation and platelet phagocytosis. This process may be of importance for progression of atherosclerotic lesions.
BNIP3 Upregulation and EndoG Translocation in Delayed Neuronal Death in Stroke and in Hypoxia
Authors: Zhang Zhengfeng , Yang Xuefen , Zhang Surong , Ma Xiuli , Kong Jiming
Published: March 2007

Background and Purpose—

Delayed neuronal death is a hallmark feature of stroke and the primary target of neuroprotective strategies. Caspase-independent apoptosis pathways are suggested as a mechanism for the delayed neuronal injury. Here we test the hypothesis that one of the caspase-independent apoptosis pathways is activated by BNIP3 and mediated by EndoG.

Methods—

We performed immunohistochemistry, Western blotting, cell transfection, subcellular fractionation, and RNA interfering to analyze the expression and localization of BNIP3 and EndoG in degenerating neurons in models of stroke and hypoxia.

Results—

BNIP3 was upregulated in brain neurons in a rat model of stroke and in cultured primary neurons exposed to hypoxia. The expressed BNIP3 was localized to mitochondria. Both forced expression of BNIP3 by plasmid transfection and induced expression of BNIP3 by hypoxia in neurons resulted in mitochondrial release and nuclear translocation of EndoG and neuronal cell death. Knockdown of BNIP3 by RNAi inhibited EndoG translocation and protected against hypoxia-induced neuronal death.

Conclusions—

BNIP3 plays a role in delayed neuronal death in hypoxia and stroke and EndoG is a mediator of the BNIP3-activated neuronal death pathway. The results suggest that BNIP3 may be a new target for neuronal rescue strategies.
Usefulness of Checking Platelet Count Before Thrombolysis in Acute Ischemic Stroke
Authors: Cucchiara Brett L. , Jackson Bryon , Weiner Mark , Messe Steven R.
Published: March 2007

Background and Purpose—

Thrombolysis for acute ischemic stroke is strikingly time sensitive. Current guidelines require confirmation of a platelet count ≥100 000 before thrombolysis; however, obtaining this laboratory test may delay treatment.

Methods—

We queried our hospital database to identify patients with ICD-9 codes consistent with acute ischemic stroke from 2000 to 2005 and to determine platelet counts in these patients. Medical charts of patients with platelet counts <100 000 were reviewed to determine whether the patient had a known history of thrombocytopenia or conditions associated with thrombocytopenia.

Results—

A total of 1752 patients were identified, and 82 (4.7%) had a platelet count <100 000 at stroke onset. Only 6/1752 (0.3%) had a platelet count <100 000 which was not suspected based on initial history. All of these 6 patients had only mildly decreased platelet counts.

Conclusions—

An unsuspected platelet count <100 000 was found in 0.3% of patients at stroke presentation. In patients without a history of thrombocytopenia or predisposing factors, the benefit of earlier thrombolysis may outweigh the bleeding risk of inadvertently treating a patient with thrombocytopenia.
Repetition and Event-related Potentials: Distinguishing Early and Late Processes in Affective Picture Perception
Authors: Codispoti Maurizio , Ferrari Vera , Bradley Margaret M.
Published: March 2007

A repetition paradigm was used to assess the nature of affective modulation of early and late components of the event-related potential (ERP) during picture viewing. High-density ERPs were measured while participants passively viewed affective or neutral pictures that were repeated up to 90 times each. Both ERP components were modulated by emotional arousal, with ERPs elicited when viewing pleasant and unpleasant pictures different than when viewing neutral pictures. On the other hand, repetition had different effects on these two components. The early occipitotemporal component (150–300 msec) primarily showed a decrease in amplitude within a block of repetitions that did not differ as a function of picture content. The late centroparietal component (300–600 msec) showed a decrease both between and within blocks of repetitions, with neutral pictures eliciting no late positive potential in the final block of the study. The data suggest that the early ERP primarily reflects obligatory perceptual processing that is facilitated by active short-term memory representations, whereas the late ERP reflects increased resource allocation due to the motivational relevance of affective cues.
On-line Integration of Semantic Information from Speech and Gesture: Insights from Event-related Brain Potentials
Authors: Özyürek Aslı , Willems Roel M. , Kita Sotaro , Hagoort Peter
Published: March 2007

During language comprehension, listeners use the global semantic representation from previous sentence or discourse context to immediately integrate the meaning of each upcoming word into the unfolding message-level representation. Here we investigate whether communicative gestures that often spontaneously co-occur with speech are processed in a similar fashion and integrated to previous sentence context in the same way as lexical meaning. Event-related potentials were measured while subjects listened to spoken sentences with a critical verb (e.g., knock), which was accompanied by an iconic co-speech gesture (i.e., KNOCK). Verbal and/or gestural semantic content matched or mismatched the content of the preceding part of the sentence. Despite the difference in the modality and in the specificity of meaning conveyed by spoken words and gestures, the latency, amplitude, and topographical distribution of both word and gesture mismatches are found to be similar, indicating that the brain integrates both types of information simultaneously. This provides evidence for the claim that neural processing in language comprehension involves the simultaneous incorporation of information coming from a broader domain of cognition than only verbal semantics. The neural evidence for similar integration of information from speech and gesture emphasizes the tight interconnection between speech and co-speech gestures.
A Neural Signature of Phonological Access: Distinguishing the Effects of Word Frequency from Familiarity and Length in Overt Picture Naming
Authors: Graves William W. , Grabowski Thomas J. , Mehta Sonya , Gordon Jean K.
Published: March 2007

Cognitive models of word production correlate the word frequency effect (i.e., the fact that words which appear with less frequency take longer to produce) with an increased processing cost to activate the whole-word (lexical) phonological representation. We performed functional magnetic resonance imaging (fMRI) while subjects produced overt naming responses to photographs of animals and manipulable objects that had high name agreement but were of varying frequency, with the purpose of identifying neural structures participating specifically in activating whole-word phonological representations, as opposed to activating lexical semantic representations or articulatory-motor routines. Blood oxygen level-dependent responses were analyzed using a parametric approach based on the frequency with which each word produced appears in the language. Parallel analyses were performed for concept familiarity and word length, which provided indices of semantic and articulatory loads. These analyses permitted us to identify regions related to word frequency alone, and therefore, likely to be related specifically to activation of phonological word forms. We hypothesized that the increased processing cost of producing lower-frequency words would correlate with activation of the left posterior inferotemporal (IT) cortex, the left posterior superior temporal gyrus (pSTG), and the left inferior frontal gyrus (IFG). Scan-time response latencies demonstrated the expected word frequency effect. Analysis of the fMRI data revealed that activity in the pSTG was modulated by frequency but not word length or concept familiarity. In contrast, parts of IT and IFG demonstrated conjoint frequency and familiarity effects, and parts of both primary motor regions demonstrated conjoint effects of frequency and word length. The results are consistent with a model of word production in which lexical-semantic and lexical-phonological information are accessed by overlapping neural systems within posterior and anterior language-related cortices, with pSTG specifically involved in accessing lexical phonology.
Feature Fusion Reveals Slow and Fast Visual Memories
Authors: Scharnowski Frank , Hermens Frouke , Kammer Thomas , Öğmen Haluk , Herzog Michael H.
Published: March 2007

Although the visual system can achieve a coarse classification of its inputs in a relatively short time, the synthesis of qualia-rich and detailed percepts can take substantially more time. If these prolonged computations were to take place in a retinotopic space, moving objects would generate extensive smear. However, under normal viewing conditions, moving objects appear relatively sharp and clear, suggesting that a substantial part of visual short-term memory takes place at a nonretinotopic locus. By using a retinotopic feature fusion and a nonretinotopic feature attribution paradigm, we provide evidence for a relatively fast retinotopic buffer and a substantially slower nonretinotopic memory. We present a simple model that can account for the dynamics of these complementary memory processes. Taken together, our results indicate that the visual system can accomplish temporal integration of information while avoiding smear by breaking off sensory memory into fast and slow components that are implemented in retinotopic and nonretinotopic loci, respectively.
Social Mind Representation: Where Does It Fail in Frontotemporal Dementia?
Authors: Ruby Perrine , Schmidt Christina , Hogge Michaël , D'Argembeau Arnaud , Collette Fabienne , Salmon Eric
Published: March 2007

We aimed at investigating social disability and its cerebral correlates in frontotemporal dementia (FTD). To do so, we contrasted answers of patients with early-stage FTD and of their relatives on personality trait judgment and on behavior prediction in social and emotional situations. Such contrasts were compared to control contrasts calculated with answers of matched controls tested with their relatives. In addition, brain metabolism was measured in patients with positron emission tomography and the [18F]fluorodeoxyglucose method. Patients turned out to be as accurate as controls in describing their relative's personality, but they failed to predict their relative's behavior in social and emotional circumstances. Concerning the self, patients were impaired both in current personality assessment and in prediction of their own behavior. Those two self-evaluation measures did not correlate. Only patients' anosognosia for social behavioral disability was found to be related to decreased metabolic activity in the left temporal pole. Such results suggest that anosognosia for social disability in FTD originates in impaired processing of emotional autobiographical information, leading to a self-representation that does not match current behavior. Moreover, we propose that perspective-taking disability participates in anosognosia, preventing patients from correcting their inaccurate self-representation based on their relative's perspective.
Dynamics of Nonlinear Feedback Control
Authors: Snippe H. P. , Hateren J. H. van
Published: March 2007

Feedback control in neural systems is ubiquitous. Here we study the mathematics of nonlinear feedback control. We compare models in which the input is multiplied by a dynamic gain (multiplicative control) with models in which the input is divided by a dynamic attenuation (divisive control). The gain signal (resp. the attenuation signal) is obtained through a concatenation of an instantaneous nonlinearity and a linear low-pass filter operating on the output of the feedback loop. For input steps, the dynamics of gain and attenuation can be very different, depending on the mathematical form of the nonlinearity and the ordering of the nonlinearity and the filtering in the feedback loop. Further, the dynamics of feedback control can be strongly asymmetrical for increment versus decrement steps of the input. Nevertheless, for each of the models studied, the nonlinearity in the feedback loop can be chosen such that immediately after an input step, the dynamics of feedback control is symmetric with respect to increments versus decrements. Finally, we study the dynamics of the output of the control loops and find conditions under which overshoots and undershoots of the output relative to the steady-state output occur when the models are stimulated with low-pass filtered steps. For small steps at the input, overshoots and undershoots of the output do not occur when the filtering in the control path is faster than the low-pass filtering at the input. For large steps at the input, however, results depend on the model, and for some of the models, multiple overshoots and undershoots can occur even with a fast control path.
Interspike Interval Statistics in the Stochastic Hodgkin-Huxley Model: Coexistence of Gamma Frequency Bursts and Highly Irregular Firing
Authors: Rowat Peter
Published: March 2007

When the classical Hodgkin-Huxley equations are simulated with Na- and K-channel noise and constant applied current, the distribution of interspike intervals is bimodal: one part is an exponential tail, as often assumed, while the other is a narrow gaussian peak centered at a short interspike interval value. The gaussian arises from bursts of spikes in the gamma-frequency range, the tail from the interburst intervals, giving overall an extraordinarily high coefficient of variation—up to 2.5 for 180,000 Na channels when I ≈ 7μAcm2. Since neurons with a bimodal ISI distribution are common, it may be a useful model for any neuron with class 2 firing. The underlying mechanism is due to a subcritical Hopf bifurcation, together with a switching region in phase-space where a fixed point is very close to a system limit cycle. This mechanism may be present in many different classes of neurons and may contribute to widely observed highly irregular neural spiking.
The Firing of an Excitable Neuron in the Presence of Stochastic Trains of Strong Synaptic Inputs
Authors: Rubin Jonathan , Josić Krešimir
Published: March 2007

We consider a fast-slow excitable system subject to a stochastic excitatory input train and show that under general conditions, its long-term behavior is captured by an irreducible Markov chain with a limiting distribution. This limiting distribution allows for the analytical calculation of the system's probability of firing in response to each input, the expected number of response failures between firings, and the distribution of slow variable values between firings. Moreover, using this approach, it is possible to understand why the system will not have a stationary distribution and why Monte Carlo simulations do not converge under certain conditions. The analytical calculations involved can be performed whenever the distribution of interexcitation intervals and the recovery dynamics of the slow variable are known. The method can be extended to other models that feature a single variable that builds up to a threshold where an instantaneous spike and reset occur. We also discuss how the Markov chain analysis generalizes to any pair of input trains, excitatory or inhibitory and synaptic or not, such that the frequencies of the two trains are sufficiently different from each other. We illustrate this analysis on a model thalamocortical (TC) cell subject to two example distributions of excitatory synaptic inputs in the cases of constant and rhythmic inhibition. The analysis shows a drastic drop in the likelihood of firing just after inhibitory onset in the case of rhythmic inhibition, relative even to the case of elevated but constant inhibition. This observation provides support for a possible mechanism for the induction of motor symptoms in Parkinson's disease and for their relief by deep brain stimulation, analyzed in Rubin and Terman (2004).
3D Periodic Human Motion Reconstruction from 2D Motion Sequences
Authors: Zhang Zonghua , Troje Nikolaus F.
Published: March 2007

We present and evaluate a method of reconstructing three-dimensional (3D) periodic human motion from two-dimensional (2D) motion sequences. Using Fourier decomposition, we construct a compact representation for periodic human motion. A low-dimensional linear motion model is learned from a training set of 3D Fourier representations by means of principal components analysis. Two-dimensional test data are projected onto this model with two approaches: least-square minimization and calculation of a maximum a posteriori probability using the Bayes' rule. We present two different experiments in which both approaches are applied to 2D data obtained from 3D walking sequences projected onto a plane. In the first experiment, we assume the viewpoint is known. In the second experiment, the horizontal viewpoint is unknown and is recovered from the 2D motion data. The results demonstrate that by using the linear model, not only can missing motion data be reconstructed, but unknown view angles for 2D test data can also be retrieved.
Profiling the Lower Troposphere over the Ocean with Infrared Hyperspectral Measurements of the Marine-Atmosphere Emitted Radiance Interferometer
Authors: Szczodrak Malgorzata , Minnett Peter J. , Nalli Nicholas R. , Feltz Wayne F.
Published: March 2007

Measurements of the spectra of infrared emission from the atmosphere were taken by a Marine-Atmospheric Emitted Radiance Interferometer (M-AERI) deployed on the NOAA ship Ronald H. Brown during the Aerosol and Ocean Science Expedition (AEROSE) in the tropical Atlantic Ocean from 29 February to 26 March 2004. The spectra are used to retrieve profiles of temperature and humidity in the lower troposphere up to a height of 3000 m. The M-AERI retrievals of the atmospheric structure require an initial guess profile. In this work, retrievals obtained from four separate initializations are compared, using 1) radiosondes launched from the Ronald H. Brown, 2) NOAA/NWS/NCEP model reanalyses, 3) ECMWF model analyses, and 4) ECMWF model forecasts. The performance of the M-AERI retrievals for all four first-guess sources is then evaluated against the radiosonde measurements. The M-AERI retrievals initialized using radiosondes reproduce the radiosonde profiles quite well and capture much of the observed vertical structure as should be expected. Of the retrievals initialized with model fields, those obtained using the ECMWF data yielded results closest to the radiosonde observations and enabled detection of the Saharan air layer (SAL) evident during AEROSE. However, the NCEP reanalysis, as well as the corresponding retrievals, failed to detect the SAL. These results demonstrate the ability of the M-AERI profile retrievals to identify the anomalous humidity distributions in the lower troposphere, but underscore the need for suitable vertical resolution in the first-guess profile used in the retrievals under such conditions.
Measurement of Total Water with a Tunable Diode Laser Hygrometer: Inlet Analysis, Calibration Procedure, and Ice Water Content Determination
Authors: Davis Sean M. , Hallar A. Gannet , Avallone Linnea M. , Engblom William
Published: March 2007

The University of Colorado closed-path tunable diode laser hygrometer (CLH), a new instrument for the in situ measurement of enhanced total water (eTW, the sum of water vapor and condensed water enhanced by a subisokinetic inlet), has recently been flown aboard the NASA DC-8 and WB-57F aircrafts. The CLH has the sensitivity necessary to quantify the ice water content (IWC) of extremely thin subvisual cirrus clouds (∼0.1 mg m−3), while still providing measurements over a large range of conditions typical of upper-tropospheric cirrus (up to 1 g m−3). A key feature of the CLH is its subisokinetic inlet system, which is described in detail in this paper. The enhancement and evaporation of ice particles that results from the heated subisokinetic inlet is described both analytically and based on computational fluid dynamical simulations of the flow around the aircraft. Laboratory mixtures of water vapor with an accuracy of 2%–10% (2σ) were used to calibrate the CLH over a wide range of water vapor mixing ratios (∼50–50 000 ppm) and pressures (∼100–1000 mb). The water vapor retrieval algorithm, which is based on the CLH instrument properties as well as on the spectroscopic properties of the water absorption line, accurately fits the calibration data to within the uncertainty of the calibration mixtures and instrument signal-to-noise ratio. A method for calculating cirrus IWC from the CLH enhanced total water measurement is presented. In this method, the particle enhancement factor is determined from an independent particle size distribution measurement and the size-dependent CLH inlet efficiency. It is shown that despite the potentially large uncertainty in particle size measurements, the error introduced by this method adds ∼5% error to the IWC calculation. IWC accuracy ranges from 20% at the largest IWC to 50% at small IWC (<5 mg m−3).
The Massachusetts Youth Screening Instrument as a Predictor of Institutional Maladjustment in Severe Male Juvenile Offenders
Authors: Butler Melanie A. , Loney Bryan R. , Kistner Janet
Published: March 2007

The Massachusetts Youth Screening Instrument—Version 2 (MAYSI-2) is a brief triage tool designed to pinpoint youth in the juvenile justice system at risk for mental health—related difficulties. The current study investigated the relation between the MAYSI-2 and institutional maladjustment at a residential treatment facility specializing in the rehabilitation of severe male juvenile offenders. Institutional maladjustment data were collected during the first 90 days of commitment for 104 male juvenile offenders who also completed the MAYSI-2 during orientation to the facility. The Angry-Irritable subscale of the MAYSI-2 uniquely predicted severe rule violations and intensive supervision placement. However, hit rate analyses revealed a high level of false negatives for the published subscale cut scores. Implications of these and related findings are discussed.
THE FAMILY → LOW SELF-CONTROL → DEVIANCE
Authors: Vazsonyi Alexander T. , Belliston Lara M.
Published: March 2007

The current investigation examined the predictive strength of family processes (closeness, support, and monitoring) both for low self-control and for a variety of deviance measures based on data from youth in seven different cultural and national groups ( N = 8,997) from Hungary, Japan, the Netherlands, Switzerland, and the United States (nonrural high school, rural high school in the “Black Belt,” and university students). Findings from multigroup structural equation modeling analyses provided consistent support for highly similar patterns of associations among family processes, low self-control, and deviance measures across groups. In addition, they also indicated that family processes had both direct and indirect effects, through low self-control, on deviance. Together, family processes and low self-control explained between 25% and 36% of the variance in deviance across samples, net the effects by age, sex, family structure, and socioeconomic status.
Knee Dislocation with Lateral Side Injury
Authors: Shelbourne K. Donald , Haro Marc S. , Gray Tinker
Published: March 2007

Background

Knee dislocations with lateral side injury are rare and disabling if not treated.

Hypothesis

An en masse surgical technique to repair the lateral side will provide good stability, and the posterior cruciate ligament will heal when left in situ.

Study Design

Case series; Level of evidence, 4.

Methods

Twenty-three patients underwent an en masse lateral side repair after knee dislocation injury; all but 1 patient had anterior cruciate ligament reconstruction. Physical examination included the International Knee Documentation Committee score, isokinetic strength testing, KT-2000 arthrometer testing, radiography (including varus stress), and magnetic resonance imaging scan. Patients were evaluated subjectively with several surveys.

Results

Mean objective evaluation occurred for 17 patients at 4.6 years postoperatively, and 21 subjective evaluations occurred for 21 patients at 5.6 years postoperatively. The objective overall grade was normal for 10 patients and nearly normal for 7 patients. Lateral laxity was graded as normal in 15 patients and 1+ in 2 patients. The posterior drawer was normal in all but 3 patients, who had 1+ posterior laxity. The postoperative varus stress radiography demonstrated a mean increase of 1.1 ± 1.7 mm (range, —1.2-4.7) between knees. Magnetic resonance scans showed that the lateral side was thickened but intact in all patients. The posterior cruciate ligament was viewed as healed or intact in all patients but was sometimes seen as elongated or buckled. The mean subjective total scores were 91.3 points for the IKDC survey, 93.0 for the modified Noyes survey, and 8.0 for an activity score, but scores were higher for patients who underwent surgery within 4 weeks from the injury.

Conclusions

The en masse surgical technique to repair the lateral side combined with an anterior cruciate ligament reconstruction after knee dislocation provides excellent long-term stability. The repaired lateral side and untreated posterior cruciate ligament heal with continuity. Patients can return to high levels of activity.
Assessment of Anterolateral Rotatory Instability in the Anterior Cruciate Ligament—Deficient Knee Using an Open Magnetic Resonance Imaging System
Authors: Okazaki Ken , Miura Hiromasa , Matsuda Shuich , Yasunaga Takefumi , Nakashima Hideaki , Konishi Kozo , Iwamoto Yukihide , Hashizume Makoto
Published: March 2007

Background

In the clinical evaluation of the anterior cruciate ligament—deficient knee, anterolateral rotatory instability is assessed by manual tests such as the pivot-shift test, which is subjective and not quantitative.

Hypothesis

The anterolateral rotatory instability in an anterior cruciate ligament—deficient knee can be quantified by our newly developed method using open magnetic resonance imaging.

Study Design

Controlled laboratory study.

Methods

Eighteen subjects with anterior cruciate ligament—deficient knees and 18 with normal knees were recruited. We administered the Slocum anterolateral rotatory instability test in the open magnetic resonance imaging scanner and scanned the sagittal view of the knee. The anterior displacements of the tibia at the medial and lateral compartments were measured. Furthermore, we examined 14 anterior cruciate ligament—deficient knees twice to assess intraobserver and interobserver reproducibility and evaluated the difference and interclass correlation coefficient of 2 measures.

Results

In the anterior cruciate ligament—deficient knee, displacement was 14.4 ± 5.5 mm at the lateral compartment and 1.6 ± 2.3 mm at the medial compartment; in the normal knee, displacement was 0.7 ± 1.9 mm and —1.1 ± 1.2 mm, respectively. The difference and interclass correlation coefficient between 2 repeated measures at the lateral compartment were 1.0 ± 0.7 mm and .98 for intraobserver reproducibility and 1.1 ± 0.7 mm and .91 for interobserver reproducibility.

Conclusion

This method is useful to assess the anterolateral rotatory instability of the anterior cruciate ligament—deficient knee.

Clinical Relevance

This method can be used in the clinical assessment of anterior cruciate ligament stability, such as comparing studies of graft positions or 2-bundle anatomic reconstruction and the conventional 1-bundle technique.
The Challenges of Modernizing Tax Administration
Authors: Aberbach Joel D. , Christensen Tom
Published: March 2007

Customer friendliness in tax systems typically characterized by control and enforcement appears to be a contradiction in terms. But many tax agencies, like other types of public organizations, have become more customer-oriented in the last few decades. This article, comparing the administration of tax systems in Norway and the USA, describes and analyzes the driving forces behind the consumer orientation movement in tax administration in the two nations and the dilemmas and effects of trying to balance control and service. Using a broad transformative perspective, we analyze structural and cultural changes in tax administration that are related to the increase in customer orientation and also consider the symbolic aspects of catering more to taxpayers. Norway and the USA have experienced similar structural reforms, but the two countries deviate rather sharply in other respects, particularly in the much larger impact of consumer-oriented reforms in the USA.
Of Roles and Rules
Authors: Leach Steve , Lowndes Vivien
Published: March 2007

In Britain the formal institutional framework within which local leadership takes place has been transformed since 1997 — through new arrangements for executive decision-making and the introduction of `comprehensive performance assessment'. The article looks at how such changes have affected the relationship between political and managerial leaders in local government. Drawing on primary research, the article examines the interaction between the formal changes associated with `modernization' and existing conventions governing the leader—chief executive relationship. Many `informal rules' still persist, serving sometimes to reinforce new expectations and sometimes to undermine them. But other informal rules are being modified, and some entirely new rules are being created, as political leaders and chief executives interpret the new landscape and renegotiate their division of labour. Old habits do indeed die hard, but — paradoxically — they may also form the raw material out of which new working rules are fashioned. The research suggests that the most effective reform strategies are those that seek to exploit, rather than frustrate, the efforts of intelligent institutional entrepreneurs on the ground.
The Politics of Partnership
Authors: Evans Brendan
Published: March 2007

The prevailing discourse on local governance is that local authorities are subordinate both to central government and to a plethora of local partners. While Manchester City Council (MCC) remains subordinate to central government, its status enables it to exert influence over the urban domain within its boundaries and to act as an intermediate organization between its local partners and the core executive in Whitehall. This reflects the influence that MCC has been able to maintain over the process of urban regeneration within its territory despite the other structures involved, and the creation of the Urban Regeneration Company (URC) of New East Manchester (NEM). MCC may possess singular characteristics but its political style of `community leadership' need not be unique. While the local state has ceded some of its activities to other agencies in this time of multi-level governance it still enjoys a powerful overarching control that can be characterized as metagovernance.
Reintegrating Government in Third Generation Reforms of Australia and New Zealand
Authors: Halligan John
Published: March 2007

Public sector reform has persisted for a sufficient length of time in several countries to examine patterns over the longer term. Australia and New Zealand are both early and long-term reforming countries that display distinctive features as well as being Anglophone countries identified with new public management. As third generation reformers, the products of more than two decades of reform activity are becoming clearer: the starker manifestations of new public management have less prominence now and a set of distinctive trends has emerged with commonalities across the two countries. The synthesis of elements in the third generation suggests that system integration and performance are central to the prevailing approach and that an emergent model is best represented in the mid-2000s as integrating governance. The article explores the constituent elements and significance of the new model and its relationship to earlier models.