bluuebunny/crossref_metadata_2025 huggingface dataset:
Manufacturing and mechanical performance evaluation of resin-infused honeycomb composites
Authors: Menta VGK , Vuppalapati RR , Chandrashekhara K , Pfitzinger D , Phan N
Published: February 2012

In spite of numerous advantages of open-cell core sandwich composites, the applications have been limited due to the problems involved in manufacturing using low cost processes. Resin accumulation in the core is a major challenge in the fabrication of honeycomb sandwich panels using resin infusion techniques. Foam-filled cores and polymer film barriers are some of the methods used in the literature to address this issue. However, these techniques will increase the weight of the sandwich composites. In this study, honeycomb sandwich panels were manufactured using commercially available film adhesive and modified vacuum-assisted resin transfer molding process. The resin incursion into the core openings was investigated. No accumulation of resin was observed in the core. Flatwise tension, flatwise/edgewise compression, and three-point bending tests were conducted to evaluate the mechanical performance of the sandwich composites. The performance of sandwich panels during a low-velocity impact event was also evaluated. Results indicate that the vacuum-assisted resin transfer molding process can be successfully used to manufacture honeycomb composite sandwich structures using currently available barrier adhesive films.
Fiber-reinforced plastic-confined rectangular columns subjected to axial loading
Authors: Csuka Bernát , Kollár László P
Published: February 2012

In this article, a model recently published by the authors is applied for the calculation of the axial resistance of centrically loaded fiber-reinforced plastic-confined rectangular concrete columns. The calculated results of our model agree well with the experimental data found in the literature. It is shown that the stiffness of the confinement has a much stronger effect on the strength than for the case of circular cross sections. Based on the numerical results, a simplified model is introduced which can be used in engineering practice.
Stigma and Status
Authors: Wilkins Amy C.
Published: February 2012

In this article, I use in-depth interviews with Black college students at two predominantly white universities to investigate the coconstruction of race, gender, and sexuality, and to examine intersectional identities as a dynamic process rather than bounded identity. I focus on Black college men’s talk about interracial relationships. Existing research documents Black women’s angry reactions to interracial relationships, but for Black men, interracial relationships present both problems and opportunities. I examine how Black men use two distinct forms of interracial talk— “player” talk and “intimacy” talk—to negotiate racialized gendered stereotypes of Black men’s heterosexuality. By moving between forms of talk, Black men negotiate the identity tensions they face as Black upwardly mobile men. Player talk and intimacy talk both respond to and use racialized stereotypes, reworking the relationship between gender, race, and sexuality. In this case, disrupted racial boundaries uphold gender inequalities between men and women.
Work-Related Daydreams
Authors: Pisarik Christopher T. , Rowell P. Clay , Currie Lacy K.
Published: February 2012

This study was conducted to develop and examine the work-related daydream construct. The content of undergraduate college students’ daydream journals were analyzed using an exploratory qualitative research methodology. The data suggested that the work-related daydream phenomenon was a tangible and accessible process that presented fully developed career narratives. Embedded within these career narratives were elements of individuals vocational self-concepts (i.e., work values, aspirations, life roles, and lifestyle choices). Six work-related daydreams are described in detail. Implications for the use of work-related daydreams as a career assessment technique are discussed.
Effect of sheet-metal thickness and hardness on the life cycle and sliding force of a novel ultraslim spring unit for a semi-automatic sliding mechanism used in IT devices
Authors: Jeon Yong-phil , Seo Hyung-yoon , Kim Jong-Deok , Kang Chung-gil
Published: February 2012

Great strides made in the industries manufacturing components for IT devices have facilitated the development of cellular phones that are either similar in size or smaller than previously existing phones. In addition, the functions carried out by devices such as MP3 players, digital cameras, and GPS devices are now being incorporated into cellular phone, the quintessential IT device. However, there are limitations on the extent to which the sizes of the components can be reduced due to technical reasons pertaining to mechanical and/or electrical properties, the manufacturing process, and the structure of the assembly. In addition, more emphasis than ever is being placed on the design of a cellular phone as it has come to be regarded as a necessity; thus, like an accessory, it needs to be stylish, highly mobile, and portable, regardless of advances in technology. To develop phones that meet these requirements, the thickness and degree of design freedom have to be reduced and improved, respectively. With this in mind, we propose a novel spring unit for the slide mechanism of a cellular phone as a practical alternative not only for maintaining the mobility and portability of the phone, but also for increasing competitiveness as this component helps to reduce the thickness of the phone. In addition, it provides a degree of freedom that allows other hardware components in the phone to be placed and adjusted more freely than conventional spring units built for the same purpose. Experiments conducted indicate that the life cycles and sliding forces of our proposed spring can be easily set by merely controlling the thickness and hardness of the sheet metal plate used for fabricating the spring. Furthermore, our proposed spring can be used to further reduce the thickness of the existing IT devices while preserving their performance and reliability. We believe that our etching process using heat-treated sheet metal can be widely applied to fabricate springs for various applications that require minimized thickness.
Biomechanical measurements of axial crush injury to the distal condyles of human and synthetic femurs
Authors: Crookshank Meghan , Coquim Jason , Olsen Michael , Schemitsch Emil H , Bougherara Habiba , Zdero Rad
Published: February 2012

Few studies have evaluated the ‘bulk’ mechanical properties of human longbones and even fewer have compared human tissue to the synthetic longbones increasingly being used by researchers. Distal femur fractures, for example, comprise about 6% of all femur fractures, but the mechanical properties of the distal condyles of intact human and synthetic femurs have not been well quantified in the literature. To this end, the distal portions of a series of 16 human fresh-frozen femurs and six synthetic femurs were prepared identically for mechanical testing. Using a flat metal plate, an axial ‘crush’ force was applied in-line with the long axis of the femurs. The two femur groups were statistically compared and values correlated to age, size, and bone quality. Results yielded the following: crush stiffness (human, 1545 ± 728 N/mm; synthetic, 3063 ± 1243 N/mm; p = 0.002); crush strength (human, 10.3 ± 3.1 kN; synthetic, 12.9 ± 1.7 kN; p = 0.074); crush displacement (human, 6.1 ± 1.8 mm; synthetic, 2.8 ± 0.3 mm; p = 0.000); and crush energy (human, 34.8 ± 15.9 J; synthetic, 18.1 ± 5.7 J; p = 0.023). For the human femurs, there were poor correlations between mechanical properties versus age, size, and bone quality (R2 ≤ 0.18), with the exception of crush strength versus bone mineral density (R2 = 0.33) and T-score (R2 = 0.25). Human femurs failed mostly by condyle ‘roll back’ buckling (15 of 16 cases) and/or unicondylar or bicondylar fracture (7 of 16 cases), while synthetic femurs all failed by wedging apart of the condyles resulting in either fully or partially displaced condylar fractures (6 of 6 cases). These findings have practical implications on the use of a flat plate load applicator to reproduce real-life clinical failure modes of human femurs and the appropriate use of synthetic femurs. To the authors’ knowledge, this is the first study to have done such an assessment on human and synthetic femurs.
Your past is not their present: Time, the other, and ethnocentrism in cross-cultural personality psychology
Authors: Adams Matthew , Hanna Paul
Published: February 2012

Recent cross-cultural studies of personality traits have been ambitious in their scope, bringing together dozens of researchers to measure personality across many cultures. The key claim made in this paper is that a persistent form of ethnocentrism mars the presentation and interpretation of findings in cross-cultural studies of personality traits using evolutionary approaches. It is a form long-established as problematic and referred to in anthropology and related social science disciplines as allochronic discourse. A significant research report will be analysed to explore how allochronic discourse, conceptualizations of time, and representations of “otherness” are utilized. The reproduction of allochronic discourse is argued to indicate a need for cross-cultural personality psychologists to engage in multi-disciplinary debate, embrace innovative methodologies, and acknowledge the cultural specificity of its own conceptual frameworks.
How safe is the use of herbal weight-loss products sold over the Internet?
Authors: Ozdemir B , Sahin I , Kapucu H , Celbis O , Karakoc Y , Erdogan S , Onal Y
Published: February 2012

Background:

In recent years, the use of herbal weight-loss products sold over the Internet has rapidly increased; however, the safety of these products has not been well documented yet. More importantly, the declared ingredients in these products could be different than the marketed contents.

Methods:

Nine different herbal weight-loss products sold over the Internet were obtained. The ingredients of each product were analyzed in the Laboratory of Forensic Medicine and the Scientific and Technological Research Laboratory of Inonu University.

Results:

Although all studied weight-loss products were presented as pure herbal, three of them contain sibutramine, three contain caffeine, and three contain caffeine + temazepam. The amount of sibutramine in each capsule was found to be over 10 mg. We analyzed toxic and trace element levels of nine herbal products and found that these herbal products, even in low amounts, contain Pb, Al, Ni, and Ba.

Conclusions:

Our results indicate that herbal weight-loss products available without prescription and claimed to be purely herbal may contain pharmaceutical substances like sibutramine or temazepam in high doses. Moreover, they also may become contaminated with toxic metals. Since people commonly use these products unaware of its real constituents and without the suggestion or control of a physician, they might cause various health problems some of which might be harmful. Strict legal rules and control mechanisms must be established to minimize their possible harmful effects.
Revalidation of the Perceptions of Conscience Questionnaire (PCQ) and the Stress of Conscience Questionnaire (SCQ)
Authors: Åhlin Johan , Ericson-Lidman Eva , Norberg Astrid , Strandberg Gunilla
Published: February 2012

The Perceptions of Conscience Questionnaire (PCQ) and the Stress of Conscience Questionnaire (SCQ) have previously been developed and validated within the ‘Stress of Conscience Study’. The aim was to revalidate these two questionnaires, including two additional, theoretically and empirically significant items, on a sample of healthcare personnel working in direct contact with patients. The sample consisted of 503 healthcare personnel. To test variation and distribution among the answers, descriptive statistics, item analysis and principal component analysis (PCA) were used to examine the underlying factor structure of the questionnaires. Support for adding the new item to the PCQ was found. No support was found for adding the new item to the SCQ. Both questionnaires can be regarded as valid for Swedish settings but can be improved by rephrasing some of the PCQ items and by adding items about private life to the SCQ.
Designing optimal multiple tuned mass dampers using genetic algorithms (GAs) for mitigating the seismic response of structures
Authors: Mohebbi Mohtasham , Shakeri Kazem , Ghanbarpour Yavar , Majzoub Hossein
Published: February 2012

In this paper an effective method has been proposed for designing optimal multiple tuned mass dampers (MTMDs) to mitigate the seismic response of structures based on defining an optimization problem which considers the parameters of tuned mass dampers (TMDs) as variables and minimization of maximum structural response as an objective function while a number of constraints have been applied on TMDs response and parameters. The genetic algorithm (GA) has been used successfully for solving the optimization problem. For illustration, for a ten-story linear shear frame subjected to a filtered white noise excitation optimal MTMDs have been designed. The results have shown the simplicity and convergence behavior of the method. It has also been concluded that the performance of MTMDs depends on TMDs mass ratio, TMDs configuration and design criteria where increasing the TMDs mass ratio has improved monotonously the performance of MTMDs especially for the domain of smaller values of the mass ratio, while for this case study the number of TMDs has not been more effective. Testing the optimal MTMDs under near-field and far-field earthquakes shows that the performance of MTMDs has been influenced by input excitation. The capability of the method in considering the effect of higher modes has been shown.
Distributed vibration control of tensegrity structure
Authors: Li Tuanjie , Wang Zuowei , Li Jin , Ma Yujuan
Published: February 2012

Distributed control is a promising method for large-scale interconnected systems that are composed of several subsystems. This paper considers the design of distributed active vibration control for tensegrity structures. Based on the distributed control theory, the simplified subsystem model of the tandem interconnected system is proposed. A control strategy combining the distributed control with a μ synthesis method is developed for controlling the three-stage tensegrity structure. The simulation results show that the designed controller makes the closed-loop system stable and can suppress disturbance. The disturbance response and local control effect are improved.
Weak Ties, Labor Migration, and Environmental Impacts
Authors: Chen Xiaodong , Frank Kenneth A. , Dietz Thomas , Liu Jianguo
Published: February 2012

Debate about the substitutability of manufactured, natural, human, and social capital is at the heart of sustainability theory. Sociology can contribute to this debate by examining the processes and mechanisms by which one form of capital is substituted for another. The authors examine the substitution among different forms of capitals at China’s Wolong Nature Reserve, where the consumption of an important aspect of natural capital, fuelwood, has serious consequences for the environment. The authors found that weak social ties to people in urban settings significantly increased rural–urban labor migration. Following the chain of capital substitutions, labor migration then significantly reduced fuelwood consumption. These findings indicate policies that facilitate the development of social capital between people in Wolong and people in urban areas could substantially reduce the consumption of local natural capital. Mechanisms by which different forms of capital are substituted for one another should be considered in improving global sustainability.
Increased expression of ER stress- and hypoxia-associated molecules in grey matter lesions in multiple sclerosis
Authors: McMahon JM , McQuaid S , Reynolds R , FitzGerald UF
Published: February 2012

Background:

The endoplasmic reticulum (ER) stress pathway may play a role in the pathogenesis multiple sclerosis (MS), and while ER stress-associated molecules have been demonstrated in white matter (WM) lesions, these have not been analysed in grey matter (GM) demyelination.

Objective:

The objective was to characterise the type and frequency of GM lesions and establish expression profiles of ER stress- and hypoxia-associated markers.

Methods:

Sections from 16 MS cases and 12 non-MS controls were stained for ER stress molecules (BiP and CHOP) and hypoxia-associated D110 antigen.

Results:

Of the GM lesions analysed, 24% were type 1 (continuous between GM and WM), 22% were type 2 (entirely within GM) and the majority (54%) were type 3 (extending from pia mater). Comparison of GM lesions, MS normal-appearing grey matter (NAGM) and non-MS control tissue showed that NAGM, type 1 and type 3 lesions all had significantly increased levels of CHOP compared to controls. According to morphological and dual-labelling criteria, the majority of CHOP-positive cells were microglia. Approximately 50% of GM lesions contained D110-positive cells.

Conclusion:

These data suggest that ER stress plays an important role in GM lesion development and may be critical in activation of microglia in pre-lesional NAGM. The high number of lesions containing D110-positive cells suggests a role for hypoxic-like insult in GM lesion development.
Statistical cures and other fallacies
Authors: Cutter Gary R
Published: February 2012

Relapse rates and thus the impact of therapies have been decreasing. Why they decline and the impact on our ability to understand which treatments are better require more than simple math. The objective of this review is to discuss the impact of regression to the mean, changes in outcome effects and how we compare outcomes over time and among studies. This paper provides discourse on the topics of regression to the mean, some examples of the pitfalls of changes and some difficulties in the interpretation of the common percentage change in outcomes. The results show that we can often be deceived by what we think we see and they also demonstrate how such confusion evolves in the literature. This article aims to caution against the over-interpretation of changes from baseline, which are helped along by regression towards the mean and other factors. Furthermore, how we interpret changes from baseline requires care and not wishful thinking, coupled with careful digestion of seemingly reasonable explications of results.
Polyunsaturated fatty acids and peripheral artery disease
Authors: Grenon S Marlene , Hughes-Fulford Millie , Rapp Joseph , Conte Michael S
Published: February 2012

There is substantial evidence that polyunsaturated fatty acids (PUFAs) such as n-3 and n-6 fatty acids (FAs) play an important role in prevention of atherosclerosis. In vitro and in vivo studies focusing on the interactions between monocytes and endothelial cells have explored the molecular effects of FAs on these interactions. Epidemiological surveys, followed by large, randomized, control trials have demonstrated a reduction in major cardiovascular events with supplementation of n-3 FAs in secondary prevention settings. The evidence of beneficial effects specific to patients with peripheral artery disease (PAD) remains elusive, and is the focus of this review.
Progression of asymptomatic peripheral artery disease over 1 year
Authors: Mohler Emile R , Bundens Warner , Denenberg Julie , Medenilla Elizabeth , Hiatt William R , Criqui Michael H
Published: February 2012

The pathophysiology and time course of an individual converting from asymptomatic peripheral artery disease (PAD) to symptomatic claudication is unclear. The objectives of this study were: (1) to characterize the extent of atherosclerotic disease in individuals with an abnormal ankle–brachial index (ABI), but without claudication; and over 1 year of follow-up to (2) evaluate the progression of PAD using ultrasound imaging, (3) determine changes in the ABI and leg pain symptoms, and (4) correlate PAD progression with changes in the ABI and leg symptoms. We hypothesized that PAD progression would be associated with the development of claudication and changes in the ABI, 6-minute walk distance (6-MWD), and walking quality of life. Individuals with a reduced ABI but without typical intermittent claudication noted on community screening were invited to undergo baseline and 1-year follow-up assessment, including duplex ultrasound. The initial and repeat evaluations included measurement of the ABI, lower extremity duplex arterial mapping, and assessment of leg pain and functional status. Of the 50 people studied, 44 (88%) had significant atherosclerotic lesions in the lower extremity arteries, affecting 80 legs. A total of 33 of 50 individuals (66%) returned for the 1-year follow-up visit. On ultrasound examination, two of 18 normal legs developed PAD, and in 48 legs with PAD at baseline, 17 legs (35%) developed new or progressive lesions. Thirteen legs developed new claudication. Overall, there was no significant worsening in the ABI, 6-MWD, or the Walking Impairment Questionnaire (WIQ). However, legs with new lesions or lesion progression were significantly more likely to develop claudication, and the 13 legs (seven subjects) developing claudication showed a significant decline in the 6-MWD. In conclusion, these data indicate that a significant number of people with asymptomatic PAD show progression over 1 year, that such individuals are more likely to develop claudication, and that those developing claudication have a significant decrease in their 6-MWD.
Toward a deeper understanding of the relationship between interaction constraints and visual isomorphs
Authors: Dou Wenwen , Ziemkiewicz Caroline , Harrison Lane , Jeong Dong Hyun , Ribarsky William , Wang Xiaoyu , Chang Remco
Published: February 2012

Interaction and manual manipulation have been shown in cognitive science literature to play a critical role in problem solving. Given different types of interactions or constraints on interactions, a problem can appear to have different degrees of difficulty. While this relationship between interaction and problem solving has been well studied in the cognitive science literatures, the visual analytics community has yet to exploit this understanding for analytical problem solving. In this paper, we hypothesize that constraints on interactions and constraints encoded in visual representations can lead to strategies of varying effectiveness during problem solving. To test our hypothesis, we conducted a user study in which participants were given different levels of interaction constraints when solving a simple mathematic game called number scrabble. Number scrabble is known to have an optimal visual problem isomorph, and the goal of this study is to learn if and how the participants could derive the isomorph and to analyze the strategies that the participants utilize in solving the problem. Our results indicate that constraints on interactions do affect problem solving, and that although the optimal visual isomorph is difficult to derive, certain interaction constraints can lead to a higher chance of deriving the isomorph.
Long Term Electro-Clinical Changes in the Lennox-Gastaut Syndrome Before, During, and after the Slow Spike-Wave Pattern
Authors: Hughes John R. , Patil Vijaya K.
Published: February 2012

Patients (64) with the Lennox-Gastaut Syndrome (LGS) were followed with EEGs (602) and clinical findings over a 42 yr period, up to 51 yrs of age. Before the slow spike-wave (SSW) complex appeared, in over one half of the patients focal discharges were seen and most often (71 %) many discharges were noted, all associated with generalized seizures. With the SSW, two thirds of the patients showed additional focal discharges, again most often (72%) very many or many were noted. Clinical attacks were usually generalized but partial attacks also were seen. Although the largest absolute number of SSW complexes appeared in young children, the highest percentage of recordings with SSW was found between 25–29.9 yrs. Changes in the frequency of the spike-wave complexes were occasionally noted, not only decreasing in frequency from 3–6/sec down to 1–2/sec, but also increasing up to 3–6/sec. After the disappearance of the SSW in time, focal discharges, diffuse and focal slow waves were seen in nearly all records and complex partial seizures increased in number. This study has emphasized the importance of the cortex in the LGS and also the instability of the pattern that occasionally appears.
Efficacious Use of a Cap Shaped Coil for Transcranial Magnetic Stimulation of Descending Motor Paths
Authors: Aglio Linda S. , Kraus Karl H. , Desai Sukumar , Romero Rafael , Ramirez Marcela , Levy Walter J. , Gugino Laverne D.
Published: February 2012

We report another technique of transcranial magnetic stimulation (TMS) for exciting the originating cells of the descending corticospinal tract. A cap shaped TMS coil has been described for simultaneously exciting muscles in all four extremities. This TMS coil is useful for monitoring the functional integrity of the descending motor paths during spinal cord surgery, because information regarding the integrity of both the left and right sides of the spinal cord motor paths can be obtained concurrently. Despite the improved design of the cap coil, careful placement is required for achieving bilateral spinal cord motor responses. Cortical mapping was used to identify the optimum scalp foci for the muscles studied. The cap coil must overlap these foci to simultaneously elicit compound muscle action potentials (CMAPs) in all four extremities. Increasing TMS stimulation intensity will increase the magnitude of the acquired CMAPs responses without significantly changing latency.
Parametric vs. Non-Parametric Statistics of Low Resolution Electromagnetic Tomography (LORETA)
Authors: Thatcher R. W. , North D. , Biver C.
Published: February 2012

This study compared the relative statistical sensitivity of non-parametric and parametric statistics of 3-dimensional current sources as estimated by the EEG inverse solution Low Resolution Electromagnetic Tomography (LORETA). One would expect approximately 5% false positives (classification of a normal as abnormal) at the P < .025 level of probability (two tailed test) and approximately 1% false positives at the P < .005 level.

EEG digital samples (2 second intervals sampled 128 Hz, 1 to 2 minutes eyes closed) from 43 normal adult subjects were imported into the Key Institute's LORETA program. We then used the Key Institute's cross-spectrum and the Key Institute's LORETA output files (*.lor) as the 2,394 gray matter pixel representation of 3-dimensional currents at different frequencies. The mean and standard deviation *.lor files were computed for each of the 2,394 gray matter pixels for each of the 43 subjects. Tests of Gaussianity and different transforms were computed in order to best approximate a normal distribution for each frequency and gray matter pixel. The relative sensitivity of parametric vs. non-parametric statistics were compared using a “leave-one-out” cross validation method in which individual normal subjects were withdrawn and then statistically classified as being either normal or abnormal based on the remaining subjects.

Log10 transforms approximated Gaussian distribution in the range of 95% to 99% accuracy. Parametric Z score tests at P < .05 cross-validation demonstrated an average misclassification rate of approximately 4.25%, and range over the 2,394 gray matter pixels was 27.66% to 0.11%. At P < .01 parametric Z score cross-validation false positives were 0.26% and ranged from 6.65% to 0% false positives. The non-parametric Key Institute's t-max statistic at P < .05 had an average misclassification error rate of 7.64% and ranged from 43.37% to 0.04% false positives. The non-parametric t-max at P < .01 had an average misclassification rate of 6.67% and ranged from 41.34% to 0% false positives of the 2,394 gray matter pixels for any cross-validated normal subject.

In conclusion, adequate approximation to Gaussian distribution and high cross-validation can be achieved by the Key Institute's LORETA programs by using a log10 transform and parametric statistics, and parametric normative comparisons had lower false positive rates than the non-parametric tests.
Cognitive Impairment in Major Depressive Disorder Revealed by Event-Related Potential N270
Authors: Mao Wei , Wang Yuping , Wang Dequan
Published: February 2012

Major depressive disorder (MDD) is a mood disorder that is often accompanied by the impairment of cognitive functions. The aim of this study was to investigate the feasibility of N270 as an index for evaluating the cognitive impairment in MDD patients. Twenty-five patients with MDD diagnosed according to DSM-IV and 25 age matched normal controls performed a matching task while event-related potentials (ERPs) were recorded from their scalp. There were two kinds of stimulus pairs in this study: match condition, the second stimulus (S2) in a pair was identical to the first one (S1); mismatch condition, S2 conflicted with S1 in the color attribute. Subjects were required to press a button in the match condition and to press another button in the mismatch condition.

A negative ERP component, N270, which was considered to reflect conflict processing activity in human brain, was evoked by S2 of the mismatch condition. The patient group showed a delayed and smaller N270 than the control group. The prolongation of its peak latency was significant at P3 and P4 electrodes, and the reduction of its peak amplitude was significant at F3, F4, P3 and P4 electrodes. The amplitude of P300 elicited in the match condition was decreased in the patient group at P3 and P4 electrodes, but its latency did not differ from the control group. The results indicate that MDD patients as a group showed cognitive decline. N270 is a sensitive index in revealing cognitive impairment.
Approximate Entropy in the Electroencephalogram during Wake and Sleep
Authors: Burioka Naoto , Miyata Masanori , Cornélissen Germaine , Halberg Franz , Takeshima Takao , Kaplan Daniel T. , Suyama Hisashi , Endo Masanori , Maegaki Yoshihiro , Nomura Takashi , Tomita Yutaka , Nakashima Kenji , Shimizu Eiji
Published: February 2012

Entropy measurement can discriminate among complex systems, including deterministic, stochastic and composite systems. We evaluated the changes of approximate entropy (ApEn) in signals of the electroencephalogram (EEG) during sleep.

EEG signals were recorded from eight healthy volunteers during nightly sleep. We estimated the values of ApEn in EEG signals in each sleep stage. The ApEn values for EEG signals (mean ± SD) were 0.896 ± 0.264 during eyes-closed waking state, 0.738 ± 0.089 during Stage I, 0.615 ± 0.107 during Stage II, 0.487 ± 0.101 during Stage III, 0.397 ± 0.078 during Stage IV and 0.789 ± 0.182 during REM sleep. The ApEn values were found to differ with statistical significance among the six different stages of consciousness (ANOVA, p<0.001). ApEn of EEG was statistically significantly lower during Stage IV and higher during wake and REM sleep.

We conclude that ApEn measurement can be useful to estimate sleep stages and the complexity in brain activity.
Structure of the Spontaneous All Night Sleep in Epileptics with Polysomnography
Authors: Wang W. W. , Xie Q. H. , Wu X.
Published: February 2012

Twenty epileptics and 11 healthy controls were investigated with polysomnography. Epileptics with interictal discharges had significantly longer total recording time and longer REM latency than the controls (P<0.05). Epileptics had a more fragmentized sleep than controls. Sleep efficiency of patients with interictal discharges was lower than that of patients without them (P<0.05). Among the patients with interictal discharges, those with partial seizures had a significantly higher arousal number than those with generalized seizures (P<0.05). The number of NREM stage shifts in patients with partial seizures tended to be higher than in those with generalized seizures.
EEG Coherence Analysis in Never-Medicated Patients with Panic Disorder
Authors: Hanaoka Akira , Kikuchi Mitsuru , Komuro Ryutarou , Oka Hiroshi , Kidani Tomokazu , Ichikawa Shunsuke
Published: February 2012

To investigate the functional abnormalities in the central nervous system (CNS) of patients with panic disorder (PD), we compared the electroencephalography (EEG) coherence values in 18 never-medicated PD patients with those in age-matched normal control subjects, and examined the relationships between EEG coherence values and both the duration of disease and the severity of panic attacks. EEG data were recorded in the resting state.

The PD patients had lower coherence values with significant differences in F3–F4, C3–C4, P3–P4, F7–T5, and F8–T6. There were positive correlations for the higher alpha band between coherence values and both the duration of disease and the severity of panic attacks.

These findings provide further evidence that PD patients have a lower degree of inter-hemispheric functional connectivity in the frontal region and intra-hemispheric functional connectivity in the bilateral temporal region, and that chronic condition or frequent panic attacks in PD patients may be related to the pathophysiological CNS changes.
Clinical Database Development: Characterization of EEG Phenotypes
Authors: Johnstone J. , Gunkelman J. , Lunt J.
Published: February 2012

We propose development of evidence-based methods to guide clinical intervention in neurobehavioral syndromes based on categorization of individuals using both behavioral measures and quantification of the EEG (qEEG). Review of a large number of clinical EEG and qEEG studies suggests that it is plausible to identify a limited set of individual profiles that characterize the majority of the population. Statistical analysis has already been used to document “clusters” of qEEG features seen in populations of psychiatric patients. 1 These clusters are considered here as intermediate phenotypes, based on genetics, and are reliable indices of brain function, not isomorphic with DSM categories, and carry implications for therapeutic intervention. We call for statistical analysis methods to be applied to a broad clinical database of individuals diagnosed with neurobehavioral disorders in order to empirically define clusters of individuals who may be responsive to specific neurophysiologically based treatment interventions, namely administration of psychoactive medication and/or EEG neurofeedback. A tentative set of qEEG profiles is proposed based on clinical observation and experience. Implication for intervention with medication and neurofeedback for individuals with these neurophysiological profiles and specific qEEG patterns is presented.
Evaluation and Validity of a LORETA Normative EEG Database
Authors: Thatcher R.W. , North D. , Biver C.
Published: February 2012

To evaluate the reliability and validity of a Z-score normative EEG database for Low Resolution Electromagnetic Tomography (LORETA), EEG digital samples (2 second intervals sampled 128 Hz, 1 to 2 minutes eyes closed) were acquired from 106 normal subjects, and the cross-spectrum was computed and multiplied by the Key Institute's LORETA 2,394 gray matter pixel T Matrix. After a log10 transform or a Box-Cox transform the mean and standard deviation of the *.lor files were computed for each of the 2,394 gray matter pixels, from 1 to 30 Hz, for each of the subjects. Tests of Gaussianity were computed in order to best approximate a normal distribution for each frequency and gray matter pixel. The relative sensitivity of a Z-score database was computed by measuring the approximation to a Gaussian distribution. The validity of the LORETA normative database was evaluated by the degree to which confirmed brain pathologies were localized using the LORETA normative database.

Log10 and Box-Cox transforms approximated Gaussian distribution in the range of 95.64% to 99.75% accuracy. The percentage of normative Z-score values at 2 standard deviations ranged from 1.21% to 3.54%, and the percentage of Z-scores at 3 standard deviations ranged from 0% to 0.83%. Left temporal lobe epilepsy, right sensory motor hematoma and a right hemisphere stroke exhibited maximum Z-score deviations in the same locations as the pathologies.

We conclude: (1) Adequate approximation to a Gaussian distribution can be achieved using LORETA by using a log10 transform or a Box-Cox transform and parametric statistics, (2) a Z-Score normative database is valid with adequate sensitivity when using LORETA, and (3) the Z-score LORETA normative database also consistently localized known pathologies to the expected Brodmann areas as an hypothesis test based on the surface EEG before computing LORETA.
Efficient Application of Internet Databases for New Signal Processing Methods
Authors: Blinowska K.J. , Durka P.J.
Published: February 2012

This paper highlights the ways in which Internet databases may be efficiently used to foster the application of progress in biomedical sciences via data sharing and new algorithms. Employing the Internet to accelerate the pace of interdisciplinary research has significant potential, yet as with all new technologies, the first applications often cause more disappointment than positive outcomes. We discuss examples of solutions to the basic issues: (1) finding the relevant datasets (in portals connected via the Inter-neuro infrastructure), (2) reading the particular format in which the data was stored (using the SignalML language for metadescription of time series), (3) choosing the right method for the data analysis (we provide a brief review of the methods used for the analysis of EEGs, and discuss two of them in detail: Directed Transfer Function and Matching Pursuit), and (4) sharing the software for chosen methods of analysis (via repositories such as the eeg.pl thematic portal).
Sleep Microarchitecture in Childhood and Adolescent Depression: Temporal Coherence
Authors: Armitage Roseanne , Hoffmann Robert , Emslie Graham , Rintelmann Jeanne , Robert Jennifer
Published: February 2012

Previous work has indicated that low temporal coherence of ultradian sleep EEG rhythms is characteristic of depressed patients and women in particular. It may also be evident in depressed children and adolescents, although most published studies are limited in sample size.

The present study evaluated temporal coherence of sleep EEG rhythms in 173 children and adolescents 8–17 years of age, including 97 who met criteria for major depressive disorder (MDD) and were symptomatic but unmedicated at the time of study and 76 healthy controls. Temporal coherence of all-night sleep EEG rhythms was evaluated on the second of two nights in the laboratory. Data were coded for diagnostic group, gender and age and subjected to MANOVAs.

Temporal coherence was significantly lower in adolescents with MDD, compared to healthy controls. Findings were most robust for coherence between left and right beta and between delta and beta in both hemispheres. Both gender and age strongly influenced between-group differences, with the lowest temporal coherence among MDD girls, even in those under 13 years of age.

In conclusion, early onset depression is associated with a reduction in synchronization of sleep EEG rhythms that shows a differential maturational course in boys and girls.
Necrotizing Leukoencephalopathy Associated with Nonconvulsive Status Epilepticus and Periodic Short-Interval Diffuse Discharges: A Clinicopathological Study
Authors: Fernández-Torre J. L. , Arce F. , Martínez-Martínez M. , González-Rato J. , Infante J. , Calleja J.
Published: February 2012

We describe the clinical, neuroimaging and neuropathological features of an immunocompromised patient diagnosed as having refractory nonconvulsive status epilepticus (NCSE), and whose consecutive electroencephalograms (EEGs) revealed persistent periodic short-interval diffuse discharges (PSIDDs). Prominent subcortical white matter lesions in keeping with the diagnosis of multifocal necrotizing leukoencephalopathy may be neuropathological substrate of NCSE with persistent PSIDDs.
Quantifying Drug-Drug Interactions in Pharmaco-EEG
Authors: Barbanoj M.J. , Antonijoan R.M. , Riba J. , Valle M. , Romero S. , Jané F.
Published: February 2012

A drug interaction refers to an event in which the usual pharmacological effect of a drug is modified by other factors, most frequently additional drugs. When two drugs are administered simultaneously, or within a short time of each other, an interaction can occur that may increase or decrease the intended magnitude or duration of the effect of one or both drugs. Drugs may interact on a pharmaceutical, pharmacokinetic or pharmacodynamic basis. Pharmacodynamic interactions arise when the alteration of the effects occurs at the site of action.

This is a wide field where not only interactions between different drugs are considered but also drug and metabolites (midazolam/α-hydroxy-midazolam), enantiomers (ketamine), as well as phenomena such as tolerance (nor-diazepam) and sensitization (diazepam). Pharmacodynamic interactions can result in antagonism or synergism and can originate at a receptor level (antagonism, partial agonism, down-regulation, up-regulation), at an intraneuronal level (transduction, uptake), or at an interneuronal level (physiological pathways).

Alternatively, psychotropic drug interactions assessed through quantitative pharmaco-EEG can be viewed according to the broad underlying objective of the study: safety-oriented (ketoprofen/theophylline, lorazepam/-diphenhydramine, granisetron/haloperidol), strictly pharmacologically-oriented (benzodiazepine receptors), or broadly neuro-physiologically-oriented (diazepam/buspirone). Methodological issues are stressed, particularly drug plasma concentrations, dose-response relationships and time-course of effects (fluoxetine/buspirone), and unsolved questions are addressed (yohimbine/caffeine, hydroxizyne/alcohol).
The Relevance of QEEG to the Evaluation of Behavioral Disorders and Pharmacological Interventions
Authors: John E. Roy , Prichep Leslie S.
Published: February 2012

It has become apparent that the electrical signals recorded from the scalp of healthy individuals under standardized conditions are predictable, and that patients with a wide variety of brain disorders display activity with unusual features. It also early became apparent that centrally active medications produced striking changes in this activity. The application of computerized signal analysis to EEG recordings collected using standardized procedures has made it possible to obtain quantitative descriptions of brain electrical activity (QEEG) in normal individuals and patients with disorders of brain function or structure, as well as quantitative description of the ways in which centrally active medications alter this activity (Pharmaco-EEG or “PEEG”). With the emergence of three-dimensional EEG source localization techniques, it has recently become possible to visualize the mathematically most probable generators of QEEG abnormalities within the brain as well as the neuroanatomical regions where abnormal activity is most altered by efficacious medication.

As QEEG and PEEG have evolved, a vast body of facts has been accumulated, describing changes in the EEG or event-related potentials (ERPs) observed in a variety of brain disorders or after administration of a variety of medications. With some notable exceptions, these studies have tended to be phenomenological rather than analytic. There has not been a systematic attempt to integrate these phenomena in order to build better understanding of how the abnormal behaviors of a particular psychiatric patient might be related to the specific pattern of the deviant electrical activity, nor just how pharmacological reduction of that deviant activity may have resulted in more normal behavior.

This article is an endeavor to provide a more specific theoretical framework for understanding the relationships between the neuroanatomy and neurochemistry of the homeostatic system underlying the regulation of the QEEG, and the mechanisms revealed by Pharmaco-EEG that aid in correcting these illnesses.
Optimal Evaluation of Digital Electroencephalograms
Authors: Rodin E. , Constantino T. , van Orman C. , Funke M. , Devinsky O. , Wong P. , McIntyre H. , Swartz B. , Rodin Ernst
Published: February 2012

Currently available digital EEG equipment provides considerably greater opportunities for clinical data analysis than is generally appreciated especially when appropriate software is used. Data from 7 different laboratories that had been obtained for routine diagnostic evaluations on 7 different EEG instruments and stored on compact disks were investigated. Since the instruments do not filter the data at input, ultra slow activity down to 0.01 Hz is currently being recorded but the attenuation factor is instrument dependent. Nevertheless, relevant clinical information is potentially available in these data and needs to be explored. Several examples in regard to epilepsy are presented. Determination of seizure onset may depend on the frequencies that are examined.

The use of appropriate filter settings and viewing windows for the clinical question to be answered is stressed. Differentiation between simple and complex spike wave discharges, as well as spread of spikes, can readily be achieved by expanding the time base to 1 or 2 seconds and placing a cursor on the peak of the negative spike. Latencies in the millisecond range can then become apparent.

EEGs co-registered with MEG should be evaluated with the same software in order to allow an adequate assessment of the similarities and differences between electrical and magnetic activity. An example of a comparison of EEG, planar gradiometers and magnetometers for an averaged spike is shown.
Follow-Up Study of Learning-Disabled Children Treated with Neurofeedback or Placebo
Authors: Becerra J. , Fernández T. , Harmony T. , Caballero M.I. , Garcia F. , Fernández-Bouzas A. , Santiago-Rodriguez E. , Prado-Alcalá R.A.
Published: February 2012

This report is a 2-year follow-up to a previous study describing positive behavioral changes and a spurt of EEG maturation with theta/alpha neurofeedback (NFB) training in a group of Learning Disabled (LD) children. In a control paired group, treated with placebo, behavioral changes were not observed and the smaller maturational EEG changes observed were easily explained by increased age.

Two years later, the EEG maturational lag in Control Group children increased, reaching abnormally high theta Relative Power values; the absence of positive behavioral changes continued and the neurological diagnosis remained LD. In contrast, after 2 years EEG maturation did continue in children who belonged to the Experimental Group with previous neurofeedback training; this was accompanied by positive behavioral changes, which were reflected in remission of LD symptoms.
Similar or Disparate Brain Patterns? The Intra-Personal EEG Variability of Three Women with Multiple Personality Disorder
Authors: Lapointe A.R. , Crayton J.W. , deVito R. , Fichtner C.G. , Konopka L.M.
Published: February 2012

Quantitative EEG was used to assess the intra-personal variability of brain electrical activity for 3 women diagnosed with Multiple Personality Disorder (MPD). Two separate control groups (within-subject and between-subject) were used to test the hypothesis that the intra-personal EEG variability between 2 alters would be less than the interpersonal EEG variability between 2 controls, and similar to the intra-personal EEG variability of a single personality. This hypothesis was partially supported. In general, the 2 EEG records of a MPD subject (alter 1 vs. alter 2) were more different from one another than the 2 EEG records of a single control, but less different from one another than the EEG records of 2 separate controls. Most of the EEG variability between alters involved beta activity in the frontal and temporal lobes.