bluuebunny/crossref_metadata_2025 huggingface dataset:
Differential connections of the temporal pole with the orbital and medial prefrontal networks in macaque monkeys
Authors: Kondo Hideki , Saleem Kadharbatcha S. , Price Joseph L.
Published: September 2003

Previous studies indicate that the orbital and medial prefrontal cortex (OMPFC) is organized into “orbital” and “medial” networks, which have distinct connections with cortical, limbic, and subcortical structures. In this study, retrograde and anterograde tracer experiments in monkeys demonstrated differential connections between the medial and orbital networks and the dorsal and ventral parts of the temporal pole. The dorsal part, including dysgranular and granular areas (TGdd and TGdg), is reciprocally connected with the medial network areas on the medial wall and gyrus rectus (areas 10m, 10o, 11m, 13a, 14c, 14r, 25, and 32) and on the lateral orbital surface (areas Iai and 12o). The strongest connections are with areas 10m (caudal part), 14c, 14r, 25, 32, and Iai. The agranular temporal pole (TGa) is connected with several areas, but most strongly with medial network area 25. The granular area around the superior temporal sulcus (TGsts) and the ventral dysgranular and granular areas (TGvd and TGvg) are reciprocally connected with the orbital network (especially areas 11l, 13b, 13l, 13m, Ial, Iam, and Iapm). TGsts is strongly connected with the entire orbital network, whereas areas TGvd and TGvg have lighter and more limited connections. Intrinsic connections within the temporal pole are also restricted to dorsal or ventral parts. Together with evidence that the dorsal and ventral temporal pole are differentially connected to auditory and visual areas of the superior and inferior temporal cortex, the results indicate separate connections between these systems and the medial and orbital prefrontal networks. J. Comp. Neurol. 465:499–523, 2003. © 2003 Wiley‐Liss, Inc.
Serial hearing organs in the atympanate grasshopper Bullacris membracioides (Orthoptera, Pneumoridae)
Authors: Van Staaden Moira J. , Rieser Michael , Ott Swidbert R. , Pabst Maria A. , Römer Heiner
Published: September 2003

In different insect taxa, ears can be found on virtually any part of the body. Comparative anatomy and similarities in the embryological development of ears in divergent taxa suggest that they have evolved multiple times from ubiquitous stretch or vibration receptors, but the homology of these structures has not yet been rigorously tested. Here we provide detailed analysis of a novel set of hearing organs in a relatively “primitive” atympanate bladder grasshopper (Bullacris membracioides) that is capable of signaling acoustically over 2 km. We use morphological, physiological, and behavioral experiments to demonstrate that this species has six pairs of serially repeated abdominal ears derived from proprioceptive pleural chordotonal organs (plCOs). We demonstrate continuity in auditory function from the five posterior pairs, which are simple forms comprising 11 sensilla and resembling plCOs in other grasshoppers, to the more complex anterior pair, which contains 2000 sensilla and is homologous to the single pair of tympanate ears found in “modern” grasshoppers. All 12 ears are morphologically differentiated, responsive to airborne sound at frequencies and intensities that are biologically significant (tuned to 1.5 and 4 kHz; 60–98 dB SPL), and capable of mediating behavioral responses of prospective mates. These data provide evidence for the transition in function and selective advantage that must occur during evolutionary development of relatively complex organs from simpler precursors. Our results suggest that ancestral insects with simple atympanate pleural receptors may have had hearing ranges that equal or exceed those of contemporary insects with complex tympanal ears. Moreover, auditory capability may be more prevalent among modern insect taxa than the presence of overt tympana indicates. J. Comp. Neurol. 465:579–592, 2003. © 2003 Wiley‐Liss, Inc.
C‐peptide enhances insulin‐mediated cell growth and protection against high glucose–induced apoptosis in SH‐SY5Y cells
Authors: Li Zhen‐guo , Zhang Weixian , Sima Anders A. F.
Published: September 2003

Background

We have previously reported that C‐peptide exerts preventive and therapeutic effects on diabetic neuropathy in type 1 diabetic BB/Wor‐rats and that it prevents duration‐dependent hippocampal apoptosis in the same animal model. In the present study, we examined human neuroblastoma SH‐SY5Y cells to examine whether C‐peptide stimulates cell proliferation/neurite outgrowth and whether it has antiapoptotic effects.

Methods

For neurite outgrowth, serum‐starved cultures were treated with C‐peptide and/or insulin or IGF‐1. Neurites were visualized with NF‐L antibody and measured morphometrically. Cell numbers were determined using an electronic cell counter. Scrambled C‐peptide was used as a negative control. For assessment of apoptosis, SH‐SY5Y cells were incubated with 100 mM glucose for 24 h, and the effects of C‐peptide and/or insulin or IGF‐1 were examined. Apoptosis was demonstrated by transferase‐mediated dUTP nick‐end labeling (TUNEL)/4,6‐diamidino‐2‐phenylindole (DAPI) stainings, flow cytometry and changes in the expression of Bcl2. Activation of insulin signaling intermediaries was determined by Western blots. Translocation of NF‐κB was demonstrated immunocytochemically.

Results

C‐peptide but not scrambled C‐peptide stimulated cell proliferation and neurite outgrowth. In the presence of 4 nM insulin, 3 nM C‐peptide significantly increased autophosphorylation of the insulin receptor (IR) but not that of the insulin‐like growth factor 1 receptor (IGF‐1R). It stimulated phosphoinositide 3‐kinase (PI‐3 kinase) and p38 mitogen‐activated protein (MAP) kinase activation, enhanced the expression and translocation of nuclear factor‐κB (NF‐κB), promoted the expression of Bcl2 and reduced c‐jun N‐terminal kinase (JNK) phosphorylation in excess of that of insulin alone.

Conclusions

C‐peptide in the presence of insulin exerts synergistic effects on cell proliferation, neurite outgrowth and has in the presence of insulin an antiapoptotic effect on high glucose–induced apoptosis but less so on hyperosmolar‐induced apoptosis. These effects are likely to be mediated via interactions with the insulin signaling pathway. Copyright © 2003 John Wiley & Sons, Ltd.
The appearance of aggregated erythrocytes in the peripheral blood of individuals with insulin resistance
Authors: Justo Daniel , Marilus Rafael , Mardi Tamar , Tolchinsky Tatiana , Goldin Yelena , Rozenblat Meirav , Rogowski Ori , Yerushalmi Yair , Stern Naftali , Shenkerman Galina , Deutsch Varda , Zeltser David , Berliner Shlomo , Shapira Itzhak
Published: September 2003

Background

Insulin resistance is associated with low‐grade inflammatory response. The probability that the acute‐phase response is associated with enhanced erythrocyte adhesiveness/aggregation was not explored.

Methods

The degree of erythrocyte adhesiveness/aggregation was evaluated by using a simple slide test. The insulin resistance was evaluated by insulin and glucose concentrations after a night of fasting. The inflammatory response was evaluated by variables of acute‐phase response.

Results

A significant correlation (r = −0.2, p = 0.02) was noted between insulin resistance expressed as the HOMA index and the degree of erythrocyte adhesiveness/aggregation. This was probably due to the concomitant acute‐phase response and the presence of increased amounts of inflammation‐sensitive proteins that were found to correlate significantly with the degree of erythrocyte adhesiveness/aggregation. In the multiple linear regression analysis, erythrocyte sedimentation rate and fibrinogen concentration but not HOMA index were found to correlate significantly (p < 0.0001 and p = 0.0007 respectively) with the degree of red blood cell adhesiveness/aggregation.

Conclusions

Insulin resistance is associated with an enhanced degree of erythrocyte adhesiveness/aggregation and this is related to the presence of enhanced inflammation‐sensitive plasma proteins that are part of the acute‐phase response. These findings might have hemorheological consequences and might contribute to the pathophysiology of the insulin‐resistance syndrome. Copyright © 2003 John Wiley & Sons, Ltd.
Cross‐cultural comparisons of anxiety and depression in adults with type 1 diabetes
Authors: Lloyd Cathy E. , Zgibor Janice , Wilson Robb R. , Barnett Anthony H. , Dyer Philip H. , Orchard Trevor J.
Published: September 2003

Background

Symptoms of depression and anxiety may be more prevalent in individuals with diabetes; however, little is known about possible differences with respect to social or cultural environment. The aim of this study was to examine cross‐cultural differences in prevalence and correlates of symptoms of anxiety and depression in two studies, one in the United Kingdom and one in the United States.

Methods

Adults with type 1 diabetes participating in two studies in Birmingham, UK, and Pittsburgh, US, completed psychosocial questionnaires including the Beck Depression Inventory and the Beck Anxiety Scale.

Results

UK subjects were significantly more likely to report moderate–severe levels of anxiety compared to US subjects (17% vs 5%; p < 0.001). Similar proportions of UK and US subjects reported moderate–severe levels of depressive symptomatology (9% vs 7%). Gender differences in symptomatology were more apparent in the US sample than in the UK study population. Multiple regression analysis demonstrated that for the UK study, symptoms of depression, less physical activity and greater frequency of blood glucose monitoring were significantly associated with symptoms of anxiety. Symptoms of depression were also significantly associated with anxiety in the US sample. For UK subjects, depressive symptoms were significantly associated with higher anxiety scores, whereas in the US subjects, anxiety and smoking were significant independent correlates of depression.

Conclusions

These data suggest that there may be cultural and/or gender differences in the experience of symptoms of anxiety and depression, and also differences in the relationship between psychological symptomatology and diabetes self‐care. Our findings have implications for the understanding of the role psychosocial factors play in the management of diabetes. Copyright © 2003 John Wiley & Sons, Ltd.
Peripheral neuropathy and microangiopathy in rats with insulinoma: association with chronic hyperinsulinemia
Authors: Sugimoto Kazuhiro , Baba Masayuki , Suda Toshihiro , Yasujima Minoru , Yagihashi Soroku
Published: September 2003

Background

Hypoglycemia can precipitate or worsen peripheral neuropathy in patients with insulinoma or in diabetic patients on an intensive insulin regimen. It still remains unclear as to whether hyperinsulinemia itself is involved in neuropathic changes in these patients. We, therefore, explored the possible isolated effects of chronic hyperinsulinemia on neuropathic changes in insulinoma‐bearing rats (I‐rats).

Methods

I‐rats were generated by a combined treatment with nicotinamide and streptozotocin. At 15 months after the treatment, they showed a wide range of the plasma insulin (PI) level with or without a decrease in the blood glucose (BG) level and were divided into three groups on the basis of the presence of hypoglycemia (BG < 2.5 mmol/L) or hyperinsulinemia (PI > 100 mU/L): the first exhibited only hypoglycemia, the second exhibited only hyperinsulinemia, and the third exhibited neither. Peripheral nerve function and structure as well as microvasculature were evaluated among these groups in addition to age‐matched untreated control rats (C‐rats).

Results

The first group of hypoglycemic I‐rats showed a decrease (p < 0.05) in the axon/myelin ratio and an increase (p < 0.0001) in fibers undergoing axonal degeneration compared to C‐rats, while the other two groups did not. On the other hand, the second group of hyperinsulinemic I‐rats showed a decrease (p < 0.05) in the myelinated axonal size and an increase (all p < 0.05) in the F‐wave latency and the densities of myelinated fibers and endoneurial microvessels exhibiting endothelial hyperplasia, vascular wall thickening, or pericytes debris compared to the third group of isoglycemic I‐rats without hyperinsulinemia.

Conclusion

These results suggest that hypoglycemia is associated with increased myelinated axonal damage, while hyperinsulinemia is associated with increased densities of small myelinated axons and endoneurial microvessels with microangiopathic changes in I‐rats. We, therefore, propose that the observed findings may be relevant to the complicated features of neuropathy in diabetic patients with chronic hyperinsulinemia. Copyright © 2003 John Wiley & Sons, Ltd.
The symptoms of hyperglycaemia in people with insulin‐treated diabetes: classification using principal components analysis
Authors: Warren Roderick E. , Deary Ian J. , Frier Brian M.
Published: September 2003

Background and aims

People with insulin‐treated diabetes commonly experience symptoms of hyperglycaemia, but the nature of these symptoms and their origins are poorly understood. The aims of this study were (1) to identify and classify the symptoms of hyperglycaemia experienced by people with insulin‐treated diabetes and (2) to identify patient characteristics associated with intensity of, and glycaemic threshold for, glycaemic symptoms.

Methods

Common hyperglycaemic symptoms were identified from preliminary interviews. Eighteen symptoms were used in a questionnaire. Four hundred participants estimated the intensities with which they experienced these symptoms during hyperglycaemia. Principal components analysis (PCA) was used to examine correlations between symptoms. Associations between symptom intensity, glycaemic threshold, and other characteristics were examined with multiple regression.

Results

In total, 361 participants (90.2%) reported experiencing hyperglycaemic symptoms. PCA suggested four symptom groupings: (1) feeling tense, irritability, restlessness, poor concentration (agitation) (2) thirst, dry mouth, need to urinate, not feeling right, sweet/funny taste, weakness (osmotic) (3) dizziness, blurred vision, light‐headedness, weakness (neurological) (4) headache, nausea (malaise). Mean symptom intensity was associated with younger age. The median (range) estimated blood glucose threshold for symptom onset was 15 (8–30) mmol/L; there was a weak tendency for this threshold to be elevated in people who had impaired hypoglycaemia awareness.

Conclusions

People with insulin‐treated diabetes commonly reported symptoms associated with hyperglycaemia. PCA separated these into four groups. Osmotic symptoms appear to be specific to hyperglycaemia; symptoms in the other groups may suggest underlying physiological mechanisms, but are relatively non‐specific. Symptoms are more intense in younger people and may be reported at lower blood glucose concentrations in people with normal awareness of hypoglycaemia. Copyright © 2003 John Wiley & Sons, Ltd.
Intranasally administered insulin intended for prevention of type 1 diabetes—a safety study in healthy adults
Authors: Kupila A. , Sipilä J. , Keskinen P. , Simell T. , Knip M. , Pulkki K. , Simell O.
Published: September 2003

Background

Intranasally applied insulin is one of the antigen‐specific therapies currently tested in clinical type 1 diabetes prevention trials, for example, in the Type 1 Diabetes Prediction and Prevention Study (DIPP). The possibility that the therapy may cause hypoglycaemia or local irritation and the poorly known immunological safety of mucosal application of the antigen in healthy subjects prompted this study.

Methods

We used a randomised, placebo‐controlled, double‐blinded crossover study design with 3‐week treatment periods to study the effects of once‐daily intranasal application of human short‐acting insulin without absorption‐enhancing adjuvants in 20 non‐diabetic adults. The selected 60 IU dose of insulin was equivalent to the weight‐based dose used for the DIPP children. We investigated self‐monitored blood glucose concentrations, nasal insulin effects and induction of diabetes‐associated autoantibodies.

Results

The two treatment periods showed no differences in blood glucose concentrations or in the frequency of blood glucose values higher than 3.0 mmol/L. Of the eight measured hypoglycaemic values, only one, which occurred during placebo therapy, was associated with symptoms. Rhinoscopy revealed no nasal irritation, and mucociliary clearance, nasal airway patency and nasal airflow resistance were not affected by the insulin therapy. Eleven subjects complained of transient nasal stinging or unpleasant odour and one subject reduced the dose because of nasal irritation. The treatment did not induce production of any of the four diabetes‐associated autoantibodies.

Conclusions

Short‐term use of intranasal insulin without absorption enhancers was predominantly well tolerated, the risk of hypoglycaemia was minimal and no objective nasal adverse effects were detected. Copyright © 2003 John Wiley & Sons, Ltd.
C‐peptide makes a comeback
Authors: Wahren John
Published: September 2003

Proinsulin C‐peptide was for long considered to be without biological activity of its own. New findings demonstrate, however, that it is capable of eliciting both molecular and physiological effects, suggesting that C‐peptide is in fact a bioactive peptide. When administered in replacement doses to animal models or to patients with type 1 diabetes, C‐peptide ameliorates diabetes‐induced functional and structural changes in both the kidneys and the peripheral nerves. It augments blood flow in a number of tissues, notably skeletal muscle, myocardium, skin and nerve. These effects are thought to be mediated via a stimulatory influence on Na+,K+‐ATPase and on endothelial nitric oxide synthase. Specific binding of C‐peptide to cell membranes of intact cells and to detergent‐solubilized cellular components has been demonstrated, indicating the existence of cell‐surface binding sites for C‐peptide. A number of intracellular responses are elicited by C‐peptide, including a rise in Ca2+ concentration and activation of MAP‐kinase signaling pathways. Many but not all of C‐peptide's intracellular effects can be inhibited by pertussis toxin, supporting the notion that C‐peptide may interact via a G‐protein‐coupled receptor. Additional data suggest that C‐peptide may interact synergistically also in the insulin signaling pathway. Combined, the available observations show conclusively that C‐peptide is biologically active, even though its molecular mechanism of action is not as yet fully understood. The possibility that replacement of C‐peptide in patients with type 1 diabetes may serve to retard or prevent the development of long‐term complications should be evaluated. Copyright © 2003 John Wiley & Sons, Ltd.
Glucosensing neurons in the ventromedial hypothalamic nucleus (VMN) and hypoglycemia‐associated autonomic failure (HAAF)
Authors: Routh Vanessa H.
Published: September 2003

Hypoglycemia is a profound threat to the brain since glucose is its preferred fuel. Thus, decreases in plasma glucose must be sensed and appropriate hormonal and neuroendocrine responses generated to restore glucose to safe levels (i.e. counterregulatory responses (CRR) to hypoglycemia). Recurrent hypoglycemia impairs these protective mechanisms, resulting in a potentially life‐threatening condition known as hypoglycemia‐associated autonomic failure (HAAF). During HAAF, the glycemic threshold is reset so that glucose levels must fall further before the CRR is initiated. The brain plays a critical role in sensing hypoglycemia and initiating the CRR. Additionally, many neurons may sense changes in plasma and extracellular glucose. However, the way in which central glucose sensing is integrated to lead to effective initiation of the CRR is unknown. Furthermore, the mechanisms by which this system becomes impaired during HAAF are also unknown. Glucosensing neurons in the ventromedial hypothalamic nucleus (VMN) are poised to serve an integrative function in glucose homeostasis. First, they sense glucose. Second, the VMN receives input from other glucose‐sensing areas. Finally, the VMN projects to areas linked to the regulation of the sympathoadrenal system that mediates the CRR. This review discusses VMN glucosensing neurons relative to their capacity to play a role in the regulation of the CRR and the generation of HAAF. Glucosensing neurons in the hindbrain as well as peripheral glucosensors are also considered. Copyright © 2003 John Wiley & Sons, Ltd.
Improved glycaemic control in type 1 diabetes patients following participation per se in a clinical trial—mechanisms and implications
Authors: DeVries J. Hans , Snoek Frank J. , Kostense Piet J. , Heine Robert J.
Published: September 2003

The phenomenon of improved diabetes self‐management following participation in a clinical trial, with subsequent improvement of glycaemic control, has been acknowledged in literature but has received little attention. Also, the potential implications of such a ‘study effect’ for clinical research are poorly explored.

We review the literature and describe the effects on glycaemic and psychological outcomes in long‐term poorly controlled type 1 diabetes patients participating in a qualification phase of a Good Clinical Practice (GCP) trial. Improved glycaemic control following participation in a clinical trial is best understood as the result of improved patients' instrumental coping behaviours, including increased self‐monitoring of blood glucose (SMBG). Such improvement in self‐care with ensuing improved glycaemic control has important consequences for trial design. Firstly, benefits seen in uncontrolled trials should be interpreted with extreme caution. Secondly, unspecific study effects and the effect of a given intervention may not simply be additive. Therefore, it is wise to include a run‐in or qualification phase of adequate length before randomization in a clinical trial. A stable baseline HbA1c can thus be reached, upon which the specific effect of an intervention can be properly judged. Also, in a multi‐centre trial, a qualification phase of sufficient length will help diminish differences in terms of intensity of care provided in participating centres. Copyright © 2003 John Wiley & Sons, Ltd.
Development of cell markers for the identification and expansion of islet progenitor cells
Authors: Zhang You‐Qing , Sarvetnick Nora
Published: September 2003

Diabetes mellitus results from the anatomical or functional loss of insulin‐producing beta cells of the pancreas. Despite significant advances in current treatment, patients with diabetes still do not maintain optimal glucose levels and therefore face debilitating complications such as hypoglycemia, retinopathy or cardiovascular diseases later in life. Islet transplantation therefore holds great promise as an ultimate cure for diabetes. However, the shortage of availability of donor sources of islets for transplantation has largely hampered this therapy. In this respect, the use of alternative sources of islets such as the ex vivo culture and expansion and differentiation of functional endocrine cells for treating diabetes has been a major focus of diabetes research. The identity of the islet stem/progenitor cells has remained either elusive or at least equivocal because of the lack of cell markers for identification of these cells. Recent successes in studying the organogenesis of pancreas as well as in vitro islet progenitor cell identification studies have provided tremendous insight for the cell markers that are essential in the isolation and characterization of these cells prospectively both in vivo and in vitro. If we can identify the markers that will aid the isolation and purification of islet progenitor cells, or factors that determine pancreatic cell fate, we might be able to coerce them from turning into specific endocrine cells or pancreas in vitro. This article will focus on this subject and will review the latest achievements in the study of cell markers for islet progenitor cells. Copyright © 2003 John Wiley & Sons, Ltd.
A photoacoustic study of thermal conductivity annealing curves for a silicon substrate implanted with Si ions
Authors: Takabatake Nobuya , Kobayashi Takeshi , Show Yoshiyuki , Izumi Tomio
Published: September 2003

Recrystallization by annealing is part of the processing of ion‐implanted semiconductor substrates because the ion implantation generates defects within the crystal. Furthermore, it was reported by Zammit's group [1] that the thermal conductivity of such substrates deteriorates remarkably after implantation. In light of these facts, we have analyzed the photoacoustic signal from a thin layer fabricated on a substrate by ion implantation, and have used the data to measure the thermal conductivity of the implanted layer in the depth direction. Our thermal conductivity measurements can be used to monitor the recrystallization of the implanted layer in the course of the annealing. We fabricated the samples by implanting Si ions into a region on top of a Si substrate at room temperature. The ions used in the implantation had an energy of 150 keV. The ion implantation doses were in the range from 1 × 1012 to 1 × 1016ions/cm2. The thickness of the ion‐implanted layer was measured by TEM to be 100 nm. By detecting the difference between the phases of photoacoustic signals coming from the ion‐implanted region and from the unimplanted region, we could extract the thermal conductivity of the implanted layer from the frequency modulation characteristics of this phase difference. We used this technique to measure annealing curves for the thermal conductivity. Our results indicated that in the course of restoring the crystallinity, the thermal conductivity begins to increase at about 500 °C, and by 750 °C it has recovered to almost the same value as prior to the implantation. Our measured annealing curves for the thermal conductivity correlated strongly with measurement data on the annealing curves of the ESR signal intensity from the same samples. This result makes it clear that measurement of the thermal conductivity by the photoacoustic method is an efficient way to monitor the defect density in implanted layers. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 86(10): 1–8, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.10034
Network design for streaming service on IP multicast over ATM
Authors: Sugisono Koji , Yamamoto Miki , Ikeda Hiromasa
Published: September 2003

This paper considers streaming service, which is an application of multicast communications, and discusses the network configuration used in providing IP multicast over ATM. In IP multicast over ATM, conversion from the IP multicast address to the ATM address is required. One of the methods of making this conversion is to use a multicast address resolution server (MARS). In this system, the MARS manages the member information of the multicast group. When there is a change in the membership of the group because a host joins or leaves, that host sends an information renewal message to the MARS. In streaming service, there arises a time zone in which many renewal messages to MARS are generated due to program changes and the like, so that the MARS is heavily burdened. This paper considers the case in which streaming service is introduced via MARS, and analytically derives the transmission frequency of the information renewal messages. The relations between the transmission frequency, the characteristics of the program, and the network scale are identified. Based on the results of analysis and a consideration of the effect of other traffic on the network, an adequate network design principle capable of reducing the control traffic to the MARS is presented. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 86(10): 51–59, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.10188
Contingency selection method for on‐line small signal stability monitoring
Authors: Takimoto Akira , Uchida Naoyuki
Published: September 2003

To make greater use of existing electric power transmission facilities, security assessment utilizing on‐line data is thought to be one of the effective measures that can be taken. To realize on‐line assessment of postfault small signal stability for a number of supposed contingencies, it is effective to identify severe contingencies to be analyzed with a precise assessment program, such as the S‐method. We developed a contingency selection method that has two indices for selection.

One of the indices is postfault eigenvalue estimation based on second‐order approximation of the eigenvalue change in response to system matrix change, which is effective for relatively weak nonlinear eigenvalue change. The other one is the Nonlinearity index, which indicates the strength of nonlinearity eigenvalue change. It is effective in detecting strong nonlinear eigenvalue changes that cannot be estimated correctly by second‐order approximation.

Calculation results with IEEJ Bulk Power System Models show that the proposed method can effectively decrease the number of contingencies that must be analyzed by the precise Small Signal Analysis method. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 145(4): 20–27, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10186
Continuous monitoring of developmental activity changes in cultured cortical networks
Authors: Mukai Yoshitaka , Shiina Tsuyoshi , Jimbo Yasuhiko
Published: September 2003

During development, cortical neurons show highly synchronized spontaneous activity. This spontaneous activity probably reflects the mechanisms underlying proper network formation regulated by activity‐dependent synaptic modification. To see long‐term transitions in this spontaneous activity, we constructed a microelectrode‐array (MEA)‐based continuous monitoring system. Rat cortical neurons were cultured on MEAs with 64 embedded electrodes and maintained in a conventional CO2 incubator. A perfusion system for medium changes and recording setup for electrical signals were directly connected to the MEA in the incubator. Culture medium was continuously perfused at a very slow rate (0.1 ml/h), which was quite effective at maintaining constant conditions without contamination. Using this system, we succeeded in recording spontaneous activity of cultured cortical networks, almost continuously from 5 days to more than 1 month in vitro. It was revealed that the spontaneous activity patterns showed transition from simple synchronized bursts to a complex mixture of multiple patterns, separated by a brief silent period at approximately 2 weeks in vitro. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 145(4): 28–37, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10216
Estimation of the number of EEG sources in the human brain using multidimensional directed information analysis
Authors: Sakata Osamu , Shiina Tsuyoshi , Saito Yoichi
Published: September 2003

At present, various approaches are being used to analyze brain function. One of these is the analysis of EEGs (electroencephalogram), by which it is becoming possible to evaluate brain activity and abnormalities in the brain from the EEG observed on the scalp. There remain many unknown aspects of the source of EEGs and their mechanism of propagation. A clue to such an approach is causality analysis, whose objective is to analyze causality by quantifying correlation relations, including the directions of information flow, among measurement sites, based on multiple EEG series obtained from multiple sites on the scalp. The method should be applicable to the diagnosis of disease such as the detection of individual abnormalities and failure of information propagation. Consequently, we have proposed multidimensional directed information analysis as a means of causality analysis in which the flow of information among all signals is investigated.

There are many multidimensional signals in nature, for which the number of information flow sources in unknown. It is very important to discover the number of sources. Therefore, we propose a method to estimate the number of information flow sources by multidimensional directed information analysis. In this paper, the effectiveness of the proposed method has been verified by a simulation, and the method has been applied to the EEG of a healthy subject and a patient with a cerebral organic disorder. As a result, we have found that the healthy subject had six information flow sources and the patient had nine. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 145(4): 38–45, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10218
Instability and chopping phenomena of a low‐current vacuum arc
Authors: Ding Cuie , Yanabu Satoru , Satoaki Arai
Published: September 2003

In order to elucidate instability and chopping phenomena at low current in a vacuum, we observed the phenomena while varying such parameters as the arcing time, the breaking current, the gap distance, and the parallel circuit parameters. We measured the instability initiation current, chopping current, arc voltage, arc voltage oscillation peak, and transient recovery voltage values using copper, copper chromium, and silver tungsten carbide electrodes.

It was found that the instability initiation current and the chopping current increased with increasing arcing time and decreased with increasing breaking current amplitude and gap size. In addition, the chopping current, the arc voltage oscillation peak, and the transient recovery voltage were dependent on the parallel circuit parameters, but the instability initiation current and the arc voltage were not dependent on them. We also found that the instability phenomena depended primarily on the cathode material. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 145(4): 12–19, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10224
Analysis of magnetic saturation in a salient‐pole synchronous machine after sudden three‐phase short circuit
Authors: Shima Kazuo , Ide Kazumasa , Takahashi Miyoshi
Published: September 2003

In order to evaluate magnetic saturation under subtransient and transient states of a large‐sized salient‐pole synchronous machine, the currents and leakage inductances after sudden three‐phase short circuits are analyzed by a two‐dimensional nonlinear transient finite element method (FEM). The currents are calculated both by direct and indirect methods. The direct method uses the FEM and considers fluctuation of the magnetic saturation after the short circuit. The indirect method solves Park's differential equations without fluctuation. Results of the direct method agree well with measurements. When the preshort voltage is large, fluctuation of the leakage inductances after the short is large and it greatly affects values of the short‐circuit currents. As the preshort voltage becomes large, the damper leakage inductances saturate at first, then the field leakage inductances, and finally the armature leakage inductances saturate. Although the indirect method considers saturation under the preshort condition, it gives inaccurate results and they are nearly the same as the results by the linear FEM. In general, it is thought that saturation of the leakage flux should be considered when subtransient conditions with large disturbance are analyzed. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 145(4): 46–55, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10240
Targeting Chemical and Biological Warfare Agents at the Molecular Level
Authors: Sadik Omowunmi A. , Land Walker H. , Wang Joseph
Published: September 2003

After the September 11 tragedies of 2001, scientists and law‐enforcement agencies have shown increasing concern that terrorist organizations and their “rogue” foreign government‐backers may resort to the use of chemical and/or biological agents against U.S. military or civilian targets. In addition to the right mix of policies, including security measures, intelligence gathering and training for medical personnel on how to recognize symptoms of biochemical warfare agents, the major success in combating terrorism lies in how best to respond to an attack using reliable analytical sensors. The public and regulatory agencies expect sensing methodologies and devices for homeland security to be very reliable. Quality data can only be generated by using analytical sensors that are validated and proven to be under strict design criteria, development and manufacturing controls. Electrochemical devices are ideally suited for obtaining the desired analytical information in a faster, simpler, and cheaper manner compared to traditional (lab‐based) assays and hence for meeting the requirements of decentralized biodefense applications. This articler presents a review of the major trends in monitoring technologies for chemical and biological warfare (CBW) agents. It focuses on research and development of sensors (particularly electrochemical ones), discusses how advances in molecular recognition might be used to design new multimission networked sensors (MULNETS) for homeland security. Decision flow‐charts for choosing particular analytical techniques for CBW agents are presented. Finally, the paths to designing sensors to meet the needs of today's measurement criteria are analyzed.
A Microbial Biosensor for p‐Nitrophenol Using Arthrobacter Sp.
Authors: Lei Yu , Mulchandani Priti , Chen Wilfred , Wang Joseph , Mulchandani Ashok
Published: September 2003

This article reports the construction, optimization of performance variables and analytical characterization of a sensitive and selective microbial amperometric biosensor for measurement of p‐nitrophenol (PNP), a U.S. Environmental Agency priority pollutant. The biosensor consisted of PNP‐degrading/oxidizing bacteria Arthrobacter sp. JS443 as biological sensing element and a dissolved oxygen electrode as the transducer. The best sensitivity and response time were obtained using a sensor constructed with 1.2 mg dry wt. of cells and operating in pH 7.5, 50 mM citrate‐phosphate buffer. Using these conditions, the biosensor was able to measure as low as 28 ppb (0.2 μM) of PNP selectively without interference from structurally similar compounds, such as phenol, nitrophenols and chlorophenols. The service life of the microbial biosensor is around 5 days when stored in the operating buffer at 4 °C. The applicability to lake water is demonstrated.
Multilayer Assemblies Consisting of Tri‐Vanadium‐Substituted Heteropolyanions and Its Electrocatalytic Properties
Authors: Zhai Shengyong , Liu Jianyun , Jiang Junguang , Dong ShaoJun
Published: September 2003

We describe the controlled fabrication of ultrathin multilayer films consisting of tri‐vanadium‐ substituted heteropolytungstate anions (denoted as P2W15V3) and a cationic polymer of quaternized poly (4‐vinylpyridine) partially complexed with osmium bis(2,2′‐bipyridine) (denoted as QPVP‐Os) on the 4‐aminobenzoic acid (4‐ABA) modified glassy carbon electrode (GCE) surface based on layer‐by‐layer assembly. Cyclic voltammetry and UV‐vis absorption spectrometry have been used to easily monitor the thickness and uniformity of thus‐formed multilayer films. The V‐centered redox reaction of P2W15V3 in the multilayer films can effectively catalyze the reduction of BrO$\rm{ {_{3}^{-}}}$ and NO$\rm{ {_{2}^{-}}}$. The resulting P2W15V3/QPVP‐Os multilayer film modified electrode behaves as a much promising electrochemical sensor because of the low overpotential for the catalytic reduction of BrO$\rm{ {_{3}^{-}}}$ and NO$\rm{ {_{2}^{-}}}$, and the catalytic oxidation of ascorbic acid.
Flow Injection Analysis of Ascorbic Acid in Real Samples Using a Highly Stable Chemically Modified Screen‐Printed Electrode
Authors: Zen Jyh‐Myng , Tsai Dong‐Mung , Senthil Kumar Annamalai
Published: September 2003

A silica sol‐gel glass‐coated ferricyanide‐doped Tosflex‐modified screen‐printed electrode (designated as SG/FeCN‐Ts/SPE) was used for the mediated oxidation of ascorbic acid in neutral pH. The sol‐gel overlayer was found to stabilize the Fe(CN)$\rm{ {_{6}^{3-}}}$‐Tosflex system without any foul‐off and deterioration behavior through chemical interaction between the hydrophilic sites of Tosflex and oxy‐ and/or ‐hydroxy surface functional groups of silicate. The electrochemical mediation of ascorbic acid was found to follow the Michaelis‐Menten kinetic pathway. The SG/FeCN‐Ts/SPE was very stable for repetitive measurements by flow injection analysis at 0.3 V (vs. Ag/AgCl). A linear calibration plot was obtained for ascorbic acid determination up to 300 μM with sensitivity and detection limit (S/N=3) of 2.85 nA/μM and 46 nM, respectively. The system also showed tolerable interference to uric acid, urea and carbohydrates and was used for the determination of ascorbic acid in human urine, clinical tablet and apple juice.
Differential Pulse Polarography of the Zn2+ Complexation by Glutathione Fragments Cys‐Gly and gamma‐Glu‐Cys
Authors: Cruz Vásquez Boris H. , Díaz‐Cruz José Manuel , Ariño Cristina , Esteban Miquel
Published: September 2003

The metal binding properties of glutathione (GSH) and their fragments γ‐Glu‐Cys and Cys‐Gly are of biological and environmental interest. In this work a differential pulse polarographic study of the Zn2+/γ‐Glu‐Cys and Zn2+/Cys‐Gly systems was carried out for a better understanding of the results obtained in previous studies on the Zn2+‐GSH system. In the case of γ‐Glu‐Cys, complexation with Zn2+ was not detected. In the case of Cys‐Gly, the parallel analysis, by multivariate curve resolution with alternating least squares, of data from the titration of peptide with metal and of metal with peptide suggested the presence of two types of bound Zn2+. This could be attributed to Zn2+ strongly bound to two sulfur atoms of two peptides, to form a complex of 1 : 2 stoichiometry, and to Zn2+ weakly bound to carboxylate and/or amino groups.
Acetylcholine Biosensor Based on Dendrimer Layers for Pesticides Detection
Authors: Snejdarkova Maja , Svobodova Lenka , Nikolelis Dimitrios P. , Wang Joseph , Hianik Tibor
Published: September 2003

We tested a new design of an enzyme biosensor based on acetylcholinesterase (AChE) and choline oxidase (ChO) immobilized on the supported monomolecular layer composed of poly(amidoamine) (PAMAM) dendrimers of the fourth generation (G4) mixed with 1‐hexadecanethiol (HDT). The resulting enzymatic activity, measured amperometrically, was substantially depressed in the presence of the organophosphate pesticide dimethyl‐2,2‐dichlorovinylphosphate (DDVP, Dichlorvos), carbamate pesticides carbofuran and carbamate drug eserine. The detection limits (1.3×10−3 ppb for DDVP, 0.01 ppb for carbofuran and 0.03 for eserine) were considerably lower than so far reported for AChE based amperometric and potentiometric sensors. The relative simple protocol of biosensor preparation, high sensitivity and stability is very promising for determination of environmental pollutants in field conditions.
Electrochemical Behavior of Diphenyl Disulfide and Thiophenol on Glassy Carbon and Gold Electrodes in Aprotic Media
Authors: Borsari Marco , Cannio Maria , Gavioli Giovanna
Published: September 2003

The investigation of the electrochemical reduction processes of C6H5SSC6H5 and C6H5SH in CH3CN using cyclic voltammetry indicates a different behavior on GC and Au electrodes. On GC surface adsorption phenomena are absent, the electrochemical reduction process is irreversible and diffusion controlled. For both the starting molecules the same species, C6H5S−, is formed upon reduction. The E° values of the reduction processes were determined by convolution method and the standard free energy of the SS bond of C6H5SSC6H5 estimated. On Au surface instead, a self‐assembled monolayer of C6H5SAuads originated after the SS or SH bond breaking can be observed by simply dipping the electrode in solution of C6H5SSC6H5 and C6H5SH, respectively. The properties of the SAM were investigated by electrochemical reduction of the adsorbed thiolates. On Au electrode the reduction processes involve C6H5SAuads and give rise to desorbed C6H5S−. A neutral radical is obtained by electrochemical oxidation of thiolate anion. It reacts rapidly with the electrode surface to give the S‐Au bond again.
Spectroelectrochemical Sensing Based on Multimode Selectivity Simultaneously Achievable in a Single Device. 15. Development of Portable Spectroelectrochemical Instrumentation
Authors: Monk David J. , Ridgway Thomas H. , Heineman William R. , Seliskar Carl J.
Published: September 2003

A portable spectroelectrochemical instrument capable of performing in situ sensing has been developed, extending the applicability of spectroelectrochemistry for chemical sensing. All components of the instrument were designed to facilitate real‐time simultaneous display of optical and electrochemical data for remote spectroelectrochemical measurements. Prior to this point in time, spectroelectrochemical measurements were confined to a laboratory setting, and remote analysis was not possible using custom or commercially available instrumentation. The novel instrumentation includes a software package for a portable computer, a small (paperback book sized) optical and electrochemical control unit, and an even smaller remote potentiostat. When the remote potentiostat is operated using fiber optic communication coupled with nine volt battery operation, the unit may operate for finite amounts of time at distances limited only by the attenuation of light in the optical fiber. Comparative studies of the custom instrument with commercially available electrochemical instrumentation were performed and showed excellent agreement. This unit was also tested using the ferricyanide/ferrocyanide reversible electrochemical couple by comparing it to bench top spectroelectrochemical instrumentation previously developed by our group.
Electroanalytical Study of Prussian Blue Modified Glassy Carbon Paste Electrodes
Authors: Ricci Francesco , Gonçalves Carla , Amine Aziz , Gorton Lo , Palleschi Giuseppe , Moscone Danila
Published: September 2003

Two types of glassy carbon (GC) powder (i.e., Sigradur K and Sigradur G) have been mixed with mineral oil to obtain glassy carbon paste electrodes (GCPE's). The electrochemical behavior of such electrodes at different percentages of glassy carbon has been evaluated with respect to the electrochemistry of ferricyanide as revealed with cyclic voltammetry and the best paste composition was chosen. GC was then modified with Prussian Blue (PB), mixed at different percentages with unmodified GC and with a fixed amount of mineral oil in order to obtain PB modified glassy carbon paste electrodes (PB‐GCPE's). PB‐GCPE's with different percentages of GC modified with PB (PB‐GC) were compared and the dependence on the amount of PB on their performances was evaluated by studying the parameters of cyclic voltammetry (i.e., current peak, ΔEp, anodic and cathodic current ratio, charge density) and the amperometric response to H2O2. Data interpretation based on the GC surface area is presented. GCPE's with a selected amount of PB‐GC were then tested as H2O2 probes and all the analytical parameters together with the dependence on pH were evaluated. Some preliminary experiments with these electrodes assembled as glucose, lysine and lactate biosensors are also reported.