bluuebunny/crossref_metadata_2025 huggingface dataset:
Frontotemporal and Striatal SPECT Abnormalities in Myoclonus-Dystonia: Phenotypic and Pathogenetic Considerations
Authors: Papapetropoulos Spiridon , Argyriou Andreas A. , Polychronopoulos Panagiotis , Spyridonidis Trifonas , Gourzis Philippos , Chroni Elisabeth
Published: February 2008

Background and Purpose: Myoclonus-dystonia (MD) is a rare movement disorder characterized by myoclonic jerks, dystonia and a variety of psychiatric symptoms. Neuroimaging and electrophysiologic studies have not been able to detect any specific central nervous system abnormality. We report for the first time a well-characterized case with MD and abnormal brain perfusion imaging using single photon emission computed tomography (SPECT) with 99mTc-ethyl cysteinate dimer (ECD). A review of the literature on the phenotypic and pathogenetic considerations for MD is also presented. Methods: To better define the functional regional central nervous system involvement in MD, we conducted a brain perfusion SPECT with 99mTc-ECD in a patient diagnosed with typical disease. Results: Analysis of the SPECT data revealed significantly reduced regional cerebral blood flow (rCBF) in both temporal lobes (left > right and medial > lateral). Reduced rCBF was also observed in both frontal lobes and the right caudate nucleus. Conclusions: Our findings of reduced frontotemporal and striatal rCBF in the absence of other neuroimaging and electrophysiologic findings correlate well with the clinical manifestations in our patient and suggest possible functional/metabolic involvement of these areas in the etiopathogenesis of MD.
Identification of a Glucose Permease from Mycobacterium smegmatis mc2 155
Authors: Pimentel-Schmitt Elisângela F. , Jahreis Knut , Eddy Mike P. , Amon Johannes , Burkovski Andreas , Titgemeyer Fritz
Published: February 2008

We report here the molecular identification of a glucose permease from Mycobacterium smegmatis,a model organism for our understanding of the life patterns of the major pathogens Mycobacterium tuberculosis and Mycobacterium leprae. A computer-based search of the available genome of M. smegmatis mc2 155 with the sequences of well-characterized glucose transporters revealed the gene msmeg4187 as a possible candidate. The deduced protein belongs to the major facilitator superfamily of proton symporters and facilitators and exhibits up to 53% of amino acid identity to other members of this family. Heterologous expression of msmeg4187 in an Escherichia coli glucose-negative mutant led to the restoration of growth on glucose. The determination of the biochemical features characterize MSMEG4187 (GlcP) as a high affinity (Km of 19 μM), glucose-specific permease. The results represent the first molecular characterization of a sugar permease in mycobacteria, and thus supply fundamental data for further in-depth analysis on the nutritional lifestyle of these bacteria.
Surgical Treatment of Hydatid Cysts of the Central Nervous System in the Pediatric Age (Dowling’s Technique)
Authors: Carrea Raúl , Dowling, jr Ernesto , Guevara Juan Antonio
Published: February 2008

Single hydatid cysts of the brain are rarely seen by pediatric neurosurgeons who do not reside in certain countries, i. e. Australia, Uruguay, and Argentina. It is, however, of considerable importance that every pediatric neurosurgeon be aware of the manner of diagnosis of this condition and the surgical management of these patients. Out of 35 cases of hydatidosis of the CNS and its covering observed over a 42-year period, there were 29 hydatid cysts of the brain and one of the spinal cord. Emphasis is placed on the former. Surgically, the hydatid cyst can be removed intact. The essential steps of the technique are: (1) a large flap; (2) careful handling during all the operative steps avoiding monopolar coagulation; (3) opening of the atrophic cortex overlying the cyst over an area whose diameter should be no less than three quarters of the diameter of the cyst, and (4) letting the cyst come out by just lowering the head of the operating table and instillating warm saline between the cyst and surrounding brain. In this series of hydatid cysts of the CNS, there was no operative mortality. The 20 cases in which the cyst was removed unbroken with Dowling’s technique are alive and only two have sequelae of the preoperative lesion (blind). In the 11 cases in which Dowling’s technique was not used and the cyst broke during ventriculography (3) or surgery (7, one broke spontaneously), only 7 are alive and well and there were 4 late deaths.
Functional Anatomy of Cranial Synostosis
Authors: Moss Melvin L.
Published: February 2008

An understanding of how sutural growth processes relate to the totality of cranial growth is necessary to cure the cause and not just the symptoms of cranial synostosis. There is no direct genetic determination for the origin, growth, size, shape or maintenance of bones. Rather, phenotypic expression of skeletal tissues is regulated via genetic information encoded in the cells of functional matrices. The primary morphogenetic event in neurocranial growth is the volumetric expansion of the neural mass, which causes the surrounding neurocranial capsule to expand. Calvarial bones arise at widely separated ossification centers and spread centrifugally towards each other. Premature synostosis of the human metopic suture was noted as a frequent characteristic of the cleft-palate skull. Primary morphological event associated with premature synostosis was a cranial base malformation. Cranial sutures permit passage of the neonatal head through the birth canal, permit slight relative variations between adjacent bones while keeping these same bones relatively approximated. All morphological attributes of cranial bones and of their sutures are extrinsically determined and regulated, including both the normal and premature synostosis of the cranial sutures. It seems reasonable to the author that premature synostosis originates in the early embryonic prosencephalic head organizer, which makes it developmentally understandable.
Isotope Cisternography and Ventriculography in Congenital CNS Anomalies
Authors: Glasauer Franz E.
Published: February 2008

Isotope studies are well-tolerated examinations in various congenital CNS anomalies and are valuable in demonstrating the presence of associated hydrocephalus, abnormal accumulation of isotope associated with abnormal CSF flow or a failure of absorption. In some cases these studies may be of differential diagnostic value and a helpful indicator in the choice of surgical treatment. These tests do not disturb the CSF equilibrium which is often observed following air or other contrast studies.
Dynamic Changes of Cerebrospinal Fluid in Upright and Recumbent Shunted Experimental Animals
Authors: Yamada Shokei , Ducker Thomas B. , Perot Phanor L.
Published: February 2008

The effect of positional change on intracranial CSF pressure, valve flow rates and atrial pressures were studied in 40 experimental dogs. The flow rate with a 30 to 60 mm H2O Holter valve changed from the recumbent to the head-up position: during the first minute it increased 2½ times and then progressively decreased to become stabilized 20–30 min later at a value slightly lower than the head-up value. At the same time pressure dropped rapidly to –23 mm H2O and then slowly, during 30 min to –120 mm H2O. In dogs without a shunt the pressure drop was initially similar to that of shunted dogs but recovered to almost the initial positive pressure in 30 min. The flow rate from a reservoir to the atrium through a shunt system when changing to the head-up position showed a siphon effect. Atrial pressure does not change with positioning. The findings were similar with cisternal-peritoneal shunts. Flow rate, therefore, increase in the head-up position. Negative intracranial CSF pressure was due to a siphon effect through the shunt system.
Diagnostic and Therapeutic Problems Concerning Tumors of the Vault
Authors: Choux Maurice , Gomez A. , Choux R. , Vigouroux R.P.
Published: February 2008

We observed 36 tumors of the cranial vault in children (11 epidermoid and dermoid cysts, 3 meningiomas, 3 malignant tumors, 11 vascular tumors, 6 eosinophilic granulomas, 2 osteomas). The common clinical finding enabling us to include all 36 tumors in this study is a large tumefaction of the cranial vault, without our being able to determine its anatomical starting point or histological nature. These observations are described according to whether they have a bony, dural or cutaneous origin, differentiating tumors of embryological origin. In the majority of cases, internal and external carotid angiography was performed to help surgery, which remains the only cure.
Manifestations and Management of Arnold-Chiari Malformation in Patients with Myelomeningocele
Authors: Hoffman Harold J. , Hendrick Bruce , Humphreys Robin P.
Published: February 2008

As a result of the authors’ experience they advocate posterior fossa decompression in patients with myelomeningocele at the first sign of compression of brain stem or the cervical cord or both. If decompression is not undertaken at once the impaired gag and cough reflexes place the child at risk. He may develop pneumonia. If decompression is delayed too long full neurological recovery will not occur. The removal of bone and the opening of dura must be carried down to the bottom of the tonsillar tip, sometimes as low as C7. The most dramatic improvement occurs in infants whose symptoms are life threatening. Less dramatic but just as real is the improvement in older children. Although investigations such as myelography and ventriculography will show the malformation, they are not essential. The associated visible malformations and the clinical condition are the most reliable means of making the diagnosis. Delaying the decompression risks the life of the infant and threatens the quality of life for the older child.
Extradural Hematomas in Children
Authors: Choux Maurice , Grisoli François , Peragut Jean-Claude
Published: February 2008

The authors have studied the clinical features of 104 extradural hematomas in children. The frequency of this complication seems rather high and its severity undeniable. 17 cases were observed in newborns and 2 cases were localized in the posterior fossa. From a clinical point of view, 57% of the children had no disturbances in consciousness at the time of the injury, and 7% had no disturbances at anytime. A lucid interval was found in 68% of the cases, and this was less than 24 h in 60% of the cases. In 19% of the cases there was no skull fracture. Angiography allowed correct diagnosis and a better choice of the surgical technique. The hematoma was distinctly localized in 59 children, whereas it was widespread in 45, meaning that, excepting the coronal suture, the cranial sutures do not limit the spreading of an extradural hematoma. For treatment the authors prefer a bone flap with four or five holes (90 operations). The results are rather unsatisfactory. 18 patients died and in 21 (7.2%) the motor sequelae were the most important complications.
Development of a Liposarcoma out of the Capsules of a Hygroma
Authors: Hemmer R. , Haensel G. , Friedrich H.
Published: February 2008

We treated a patient who had a very rare finding: the development of a malignoma out of the capsules of the subdural hygroma covering the right occipitotemporal brain. Lumbar encephalography and arteriography confirmed the fact that surgery was necessary. A subdural-auricular shunt was performed and revised 2 years later. During the second operation, the external and internal capsules were removed in addition to the shunt. 3 years later the hygroma and large capsules were removed again and a ventricular-subdural drainage performed. 1 year later once more a subdural-auricular shunt was performed. 10 months later a tumour was found to fill the whole occipital, temporal and parietal area. The tumour was removed and found to be a pseudomucinous liposarcoma with large hyperchromatic nuclei and oval cells with large vacuoles of neutral fat. Renewed growth of the tumour led to the child’s death. The histological and macroscopic findings of the capsules suggest the development of a malignoma within the last 3 years.
Hydrocephalus in Down’s Syndrome
Authors: Jayaraman A. , Ballweg G.P. , Donnenfeld H. , Chusid J.G.
Published: February 2008

An infant with hydrocephalus, aqueductal stenosis and partial agenesis of the corpus callosum in association with Down’s syndrome is reported. Review of the literature reveals that hydrocephalus is infrequent in Down’s syndrome. Of special interest is the occurrence of agenesis of the corpus callosum in our patient, a lesion often reported with other chromosomal abnormalities, but not previously observed in Down’s syndrome.
Hydrocephalus Secondary to Intracranial Hemorrhage in Premature Infants
Authors: Wise Burton L. , Ballard Roberta
Published: February 2008

Premature (low birth weight) infants are particularly susceptible to intracranial hemorrhage. This frequently arises from the subependymal area and may dissect into the brain or into the ventricles. If the infant survives, hydrocephalus is a frequent sequela. Because of major improvements in the care of premature infants in recent years and the proliferation of intensive care nurseries, increasing numbers of low birth weight infants are surviving and developing hydrocephalus. Seven cases are described of infants who developed hydrocephalus following intracranial bleeding. Initially, ventricular and lumbar punctures were done to attempt to control head growth but this was unsuccessful. Two were treated with temporary external ventriculostomy which did not permanently control the hydrocephalus. Definitive treatment included ventriculoatrial shunts using an expandable ‘telescopic’ cardiac catheter in two and ventriculoperitoneal shunts in five. The pathogenesis and management of the condition are discussed.
Intraspinal Lipomas in Children
Authors: Villarejo F.J. , Blazquez M.G. , Gutierrez-Diaz J.A.
Published: February 2008

13 cases of intraspinal lipomas are presented. Review of the literature demonstrates the frequency, according to different authors, between true lipomas and lipomas associated with spina bifida. Etiology, clinical characteristics, and radiological findings of these cases are discussed. Finally, we stress the importance of early surgical treatment to avoid any neurological deficit.
Central Neurogenic Pulmonary Edema: With a Review of its Pathogenesis and Treatment
Authors: Kosnik Edward J. , Paul Stephen E. , Rossel Charles W. , Sayers Martin P.
Published: February 2008

One of the unusual signs of sudden increase in intracranial pressure is central neurogenic pulmonary edema. This pulmonary edema produces a capillary-aveolar block resulting in hypoxia complicating the underlying neurologic condition. Good success in treating this problem has been obtained with controlled ventilation and positive end expiratory pressure respiration.
Nelson’s Syndrome in the Paediatric Age
Authors: Forni C. , Giovanelli M.A.
Published: February 2008

A pituitary adenoma was discovered in a 9-year-old boy 4 years after he underwent a bilateral adrenalectomy for Cushing’s syndrome.
AP-1–Dependent Transcriptional Regulation of NADPH Oxidase in Human Aortic Smooth Muscle Cells
Authors: Manea Adrian , Manea Simona A. , Gafencu Anca V. , Raicu Monica , Simionescu Maya
Published: February 2008

Objective—

NADPH oxidase (NADPHox) is the major source of reactive oxygen species in vascular diseases; the mechanisms of enzyme activation are not completely elucidated. AP-1 controls the expression of many genes linked to vascular smooth muscle cells (SMCs) dysfunction. In this study we searched for the role of AP-1 in the regulation of NADPHox expression and function in human aortic SMCs exposed to proinflammatory conditions.

Methods and Results—

Cultured SMCs were exposed to either angiotensin II (Ang II) or tumor necrosis factor (TNF)-α. The lucigenin-enhanced chemiluminescence assay and real-time polymerase chain reaction analysis revealed that AP-1 and mitogen-activated protein kinase inhibitors reduced both Ang II or TNF-α-dependent upregulation of NADPHox activity and mRNA expression (NOX1, NOX4, p67
phox
, p47
phox
, p22
phox
). Inhibitors of AP-1 significantly diminished the Ang II or TNF-α-stimulated p22
phox
promoter activity and protein level. Transient overexpression of c-Jun/c-Fos upregulated p22
phox
promoter activity. Transcription factor pull-down assay and chromatin immunoprecipitation demonstrated the physical interaction of c-Jun protein with predicted AP-1–binding sites in the p22
phox
gene promoter.

Conclusions—

In SMCs exposed to Ang II or TNF-α, inhibition of AP-1–related pathways reduces NADPHox expression and the O
2
−
production. The physical interaction of AP-1 with p22
phox
gene promoter facilitates NADPHox regulation.
Is Routine Retinal Examination Useful in Patients With Acute Ischemic Stroke?
Authors: De Silva Deidre A. , Wong Tien Y. , Chang Hui-Meng , Ng Bee-Fang , Tikellis Gabriella , Saw Seang Mei , Woon Fung-Peng , Chen Christopher P.L.H. , Wong Meng-Cheong
Published: February 2008

Background and Purpose—

Patients with ischemic stroke have a high prevalence of hypertension and diabetes, which are major risk factors for potentially blinding retinal diseases. We studied the prevalence of retinal diseases, and the need for an ophthalmology referral, among persons with acute ischemic stroke.

Methods—

We conducted a prospective study of 300 consecutive patients with acute ischemic stroke. Retinal photographs were taken and assessed in a masked fashion. Patients were advised and referred if they required an ophthalmology evaluation.

Results—

Of the 286 patients with gradable photographs, retinal abnormalities were detected in 59%. Ophthalmology evaluation was advised for 3% of patients on an urgent basis and 28% on a nonurgent basis and resulted in either acute treatment or active follow-up for all who were subsequently reviewed.

Conclusions—

Patients with acute ischemic stroke have a high prevalence of retinal abnormalities. This study suggests that a routine retinal examination may provide an opportunity to detect potentially vision-threatening retinal diseases.
Preliminary Findings of External Counterpulsation for Ischemic Stroke Patient With Large Artery Occlusive Disease
Authors: Han Jing Hao , Leung Thomas W. , Lam Wynnie W. , Soo Yannie O. , Alexandrov Anne W. , Mok Vincent , Leung Yee-Fong V. , Lo Raymond , Wong Ka Sing
Published: February 2008

Background and Purpose—

We aimed to investigate the feasibility and therapeutic effect of external counterpulsation (ECP) in ischemic stroke.

Methods—

The trial was a randomized, crossover, assessment-blinded, proof-of-concept trial. ECP treatment consisted of 35 daily 1-hour sessions. Patients were randomized to either early (ECP weeks 1 to 7 and no ECP weeks 8 to 14) or late group (no ECP weeks 1 to 7 and ECP weeks 8 to 14). Primary outcomes were an overall change in National Institutes of Health Stroke Scale (NIHSS) and cerebral blood flow estimated by color velocity imaging quantification. Secondary outcomes were change in NIHSS, color velocity imaging quantification, favorable functional outcome (modified Rankin scale, 0 to 2), and stroke recurrence at weeks 7 and 14, respectively.

Results—

Fifty patients were recruited. At week 7, there was a significant change in NIHSS (early 3.5 vs late 1.9;
P
=0.042). After adjusting for treatment sequence, ECP was associated with a favorable trend of change in NIHSS of 2.1 vs 1.3 for non-ECP (
P
=0.061). Changes of color velocity imaging quantification were not significant but tended to increase with ECP. At week 14, a favorable functional outcome was found in 100% of early group patients compared to 76% in the late group (
P
=0.022).

Conclusion—

ECP is feasible for ischemic stroke patients with larger artery disease.
Long-Term Fatal Outcomes in Subjects With Stroke or Transient Ischemic Attack
Authors: Patel Alpesh B. , Kostis John B. , Wilson Alan C. , Shea Michael L. , Pressel Sara L. , Davis Barry R.
Published: February 2008

Background and Purpose—

Epidemiologic studies have demonstrated that hypertension increases the risk of stroke, and clinical trials have shown that antihypertensive therapy reduces this risk. Incident stroke was significantly decreased by treatment in the Systolic Hypertension in Elderly Program (SHEP) Trial, but the reduction in fatal events was not statistically significant.

Methods—

Vital status was determined for 4736 SHEP participants by matching to the National Death Index. We assessed the impact of antihypertensive treatment, stroke, and transient ischemic attacks (TIAs) during SHEP on long-term (mean, 14.3 years) mortality.

Results—

Treatment with a chlorthalidone-based antihypertensive regimen significantly reduced the risk of cardiovascular death (adjusted relative risk [RR]=0.86; 95% CI, 0.76 to 0.98,
P
=0.026) in the SHEP cohort without a significant (
P
=0.39) interaction with stroke status. Patients who sustained a stroke during SHEP had significantly higher all-cause mortality at the 14.3-year mean follow-up: 65.6% compared with 40.6% among those free of stroke or TIA (adjusted RR=1.97; 95% CI, 1.67 to 2.33). They also were at higher risk for cardiovascular death (RR=2.00; 95% CI, 1.58 to 2.53) and stroke death (RR=2.94; 95% CI, 1.87 to 4.64). TIA was not significantly associated with increased total mortality (RR=1.13; 95% CI, 0.88 to 1.44), cardiovascular death (RR=1.30; 95% CI, 0.94 to 1.81), or stroke death (RR=1.76; 95% CI, 0.95 to 3.26).

Conclusions—

In SHEP, chlorthalidone-based treatment reduced the risk of cardiovascular death after 14 years of extended follow-up. Nearly two thirds of elderly persons with isolated systolic hypertension who experienced stroke died within 14 years.
Risk Factors and Neurological Consequences of Syncopes Induced by Internal Carotid Artery Angioplasty
Authors: Martinez-Fernandez Eva , Boza Garcia Fernando , Gonzalez-Marcos Jose R. , Gil-Peralta Alberto , Gonzalez Garcia Alejandro , Mayol Deya Antonio
Published: February 2008

Background and Purpose—Syncope and carotid sinus reactions (CSR) occur frequently in patients undergoing carotid angioplasty (CA). We investigated risk factors and the neurological consequences of carotid sinus syncope induced by CA.

Methods—We examined 359 consecutive patients. Patients underwent assessment of cerebrovascular reserve before CA and continuous electroencephalographical monitoring during the procedure. We examined the impact of vascular risk factors, cerebral hemodynamics, characteristics of plaque, and procedural modality on the incidence of CSR and syncope. The effect of syncopes on periprocedural complication rates was also investigated.

Results—CSR and syncope occurred in 62.7% and 18.0% of the procedures, respectively. The occurrence of CSR during angioplasty was significantly associated with the appearance of syncope. The incidence of syncope was significantly higher in longer plaques located in the carotid bifurcation, in the presence of contralateral carotid stenosis, or when protection devices were used. Although TIA during CA was more common in syncopal patients, stroke or death rates were similar in the 2 groups.

Conclusions—Syncope occurs more frequently in patients with long plaques proximal to the carotid bifurcation, but it does not increase the periprocedural complications rate.
Insulin Resistance as a Risk Factor for Carotid Atherosclerosis
Authors: Sourij Harald , Schmoelzer Isabella , Dittrich Peter , Paulweber Bernhard , Iglseder Bernhard , Wascher Thomas C.
Published: February 2008

Background and Purpose—

The independent contribution of insulin resistance to atherosclerosis is still under debate. We compared associations of 2 different indices of insulin resistance, the Homeostasis Model Assessment (HOMA) index and kITT from a short insulin tolerance test with carotid atherosclerosis.

Methods—

A total of 1771 middle-aged white patients were investigated. Intima media thickness (IMT) and extent of carotid atherosclerosis were quantified by ultrasound. HOMA was calculated and an insulin tolerance test was performed.

Results—

HOMA and kITT were significant predictors for average carotid IMT (
P
<0.001). After adjustment for age and the components of the metabolic syndrome, HOMA still remained an independent predictor for IMT
avg
(
P
=0.02), whereas kITT failed to do so. HOMA and kITT were also predictive (
P
=0.004 and
P
=0.024) for carotid plaques and extent of carotid atherosclerosis (
P
<0.001). After adjustment for age and the components of the metabolic syndrome, neither HOMA nor kITT were independently predictive any more.

Conclusions—

Our results provide evidence that HOMA rather than kITT is associated with carotid atherosclerosis and that the association is largely explained by the clustered expression of the components of the metabolic syndrome.
Blackened Windows: from The War Zone Is My Bed
Authors: Rana Yasmine Beverly
Published: February 2008

Behind a blackened window in Kabul, Laila, a widow, seeks solace in sex while earning her living as a prostitute. She and her lover Ash find refuge from the violence, loss, and fear that is their daily lives under the Taliban.
Biokhraphia
Authors: Saneh Lina , Mroué Rabih
Published: February 2008

This mockumentary in the form of a self-interview takes a sidelong glance at the role of the artist in Lebanon, a country torn apart by years of civil strife and war.
On Recent Performances of Luigi Nono's The Forest Is Young and Full of Life
Authors: Lochhead Judy
Published: February 2008

This issue's Critical Acts focuses on “war and other bad shit” in terms of censorship, immigration, and art as a form of political protest and recovery. In “Habeas Corpus,” Ann Pellegrini uses Sally Field's censored Emmy-acceptance speech to exemplify the Bush administration's privatization of mourning as a means “to bind us to acts of fatal violence against an objectified and dehumanized ‘enemy.’” In her account of Luigi Nono's The Forest Is Young and Full of Life, Judy Lochhead examines the possibility of music as activism, noting how history is recycled from the Vietnam War to today. William Bowling and Rachel Carrico describe how art heals in Lakeviews, part of a post-Katrina project. Guillermo Gómez-Peña rages against “border hysteria,” when the “War on Terror” becomes a “war on difference.”
Performing the Nation: Theatre in Post-Genocide Rwanda
Authors: Breed Ananda
Published: February 2008

While grassroots theatre brings together perpetrators and survivors of the Rwandan genocide, government-driven campaigns can manipulate theatre for reconciliation to serve its own nationalist agenda. The Mutabaruka company use their performances in Burundi to resurrect/construct the identity of a precolonial Rwanda; the Mashirika theatre focus on reconciling the Hutu, Tutsi, and Twa.
The Science of Breeding and Its Application to the Breeder Genetic Algorithm (BGA)
Authors: Mühlenbein Heinz , Schlierkamp-Voosen Dirk
Published: February 2008

The breeder genetic algorithm (BGA) models artificial selection as performed by human breeders. The science of breeding is based on advanced statistical methods. In this paper a connection between genetic algorithm theory and the science of breeding is made. We show how the response to selection equation and the concept of heritability can be applied to predict the behavior of the BGA. Selection, recombination, and mutation are analyzed within this framework. It is shown that recombination and mutation are complementary search operators. The theoretical results are obtained under the assumption of additive gene effects. For general fitness landscapes, regression techniques for estimating the heritability are used to analyze and control the BGA. The method of decomposing the genetic variance into an additive and a nonadditive part connects the case of additive fitness functions with the general case.
The Genetic Algorithm Fractal
Authors: Juliany Jenny , Vose Michael D.
Published: February 2008

The original schema theorem (an inequality) has been replaced by an equality that determines the expected next generation for a simple genetic algorithm. This has made possible the computation of the trajectory of expected next generations. Visualization of these evolutionary trajectories beginning from different initial populations has led to the discovery of fractal structures.
Adaptive Learning of Process Control and Profit Optimization Using a Classifier System
Authors: Gilbert A. H. , Bell Frances , Valenzuela Christine L.
Published: February 2008

A classifier system is used to learn control and profit optimization of a batch chemical reaction. Ability to learn different market conditions and changes to reaction parameters is demonstrated. The profit sharing algorithm is used for apportionment of credit. The greater effectiveness of the use of the genetic algorithm over apportionment of credit alone or the random replacement of low strength rules is also shown. The classifier system is unusual in having more than one action per rule.
Search-Intensive Concept Induction
Authors: Giordana Attilio , Neri Filippo
Published: February 2008

This paper describes REGAL, a distributed genetic algorithm-based system, designed for learning first-order logic concept descriptions from examples. The system is a hybrid of the Pittsburgh and the Michigan approaches, as the population constitutes a redundant set of partial concept descriptions, each evolved separately. In order to increase effectiveness, REGAL is specifically tailored to the concept learning task; hence, REGAL is task-dependent, but, on the other hand, domain-independent. The system proved particularly robust with respect to parameter setting across a variety of different application domains.

REGAL is based on a selection operator, called Universal Suffrage operator, provably allowing the population to asymptotically converge, on the average, to an equilibrium state in which several species coexist. The system is presented in both a serial and a parallel version, and a new distributed computational model is proposed and discussed.

The system has been tested on a simple artificial domain for the sake of illustration, and on several complex real-world and artificial domains in order to show its power and to analyze its behavior under various conditions. The results obtained so far suggest that genetic search may be a valuable alternative to logic-based approaches to learning concepts, when no (or little) a priori knowledge is available and a very large hypothesis space has to be explored.
A Numerical Approach to Genetic Programming for System Identification
Authors: Iba Hitoshi , deGaris Hugo , Sato Taisuke
Published: February 2008

This paper introduces a new approach to genetic programming (GP), based on a numerical technique, which integrates a GP-based adaptive search of tree structures, and a local parameter tuning mechanism employing statistical search (a system identification technique). In traditional GP, recombination can cause frequent disruption of building blocks or mutation can cause abrupt changes in the semantics. To overcome these difficulties, we supplement traditional GP with a local hill-climbing search, using a parameter tuning procedure. More precisely, we integrate the structural search of traditional GP with a multiple regression analysis method and establish our adaptive program, called STROGANOFF (STructured Representation On Genetic Algorithms for NOn-linear Function Fitting). The fitness evaluation is based on a minimum description length (MDL) criterion, which effectively controls the tree growth in GP. We demonstrate its effectiveness by solving several system identification (numerical) problems and compare the performance of STROGANOFF with traditional GP and another standard technique (radial basis functions). We then extend STROGANOFF to symbolic (nonnumerical) reasoning by introducing multiple types of nodes, using a modified MDL-based selection criterion and a pruning of the resultant trees. The effectiveness of this numerical approach to GP is demonstrated by successful application to symbolic regression problems.
A Note on the Empirical Evaluation of Intermediate Recombination
Authors: Fogel David B. , Beyer Hans-Georg
Published: February 2008

The effectiveness of intermediate recombination in evolution strategies is analyzed in light of the typical procedure of initializing trial solutions uniformly about the global optimum of benchmark functions. Analysis indicates that this procedure may predispose results in favor of intermediate recombination.
An Analysis of the “Universal Suffrage” Selection Operator
Authors: Neri Filippo , Saitta Lorenza
Published: February 2008

The “universal suffrage” selection operator, designed primarily for concept learning inside the system REGAL, is discussed for both overlapping and nonoverlapping populations. Analysis of its behavior is performed by using the “virtual average population” method, a new tool for investigating asymptotic properties of convergence of macroscopic quantities related to the population of a genetic algorithm.
Recent Advances in Evolvable Systems-ICES 96 (International Conference on Evolvable Systems)
Authors: Frank Ian , Manderick Bernard , Higuchi Tetsuya
Published: February 2008

This paper reviews the developments in evolvable hardware systems presented at the First International Conference on Evolvable Systems (ICES 96). The main body of the review gives an overview of the 34 papers presented orally, splitting them into three broad groups according to whether they involve (1) evolving a fit solution to a problem as a member of a population of competing candidates, (2) evolving solutions that can individually learn from and adapt to their environments, or (3) the embryonic growth of solutions. We also review the discussion sessions of the conference and give pointers to related upcoming events.
Forming Neural Networks Through Efficient and Adaptive Coevolution
Authors: Moriarty David E. , Miikkulainen Risto
Published: February 2008

This article demonstrates the advantages of a cooperative, coevolutionary search in difficult control problems. The symbiotic adaptive neuroevolution (SANE) system coevolves a population of neurons that cooperate to form a functioning neural network. In this process, neurons assume different but overlapping roles, resulting in a robust encoding of control behavior. SANE is shown to be more efficient and more adaptive and to maintain higher levels of diversity than the more common network-based population approaches. Further empirical studies illustrate the emergent neuron specializations and the different roles the neurons assume in the population.
Time Scheduling of Transit Systems With Transfer Considerations Using Genetic Algorithms
Authors: Deb Kalyanmoy , Chakroborty Partha
Published: February 2008

Scheduling of a bus transit system must be formulated as an optimization problem, if the level of service to passengers is to be maximized within the available resources. In this paper, we present a formulation of a transit system scheduling problem with the objective of minimizing the overall waiting time of transferring and nontransferring passengers while satisfying a number of resource- and service-related constraints. It is observed that the number of variables and constraints for even a simple transit system (a single bus station with three routes) is too large to tackle using classical mixed-integer optimization techniques. The paper shows that genetic algorithms (GAs) are ideal for these problems, mainly because they (i) naturally handle binary variables, thereby taking care of transfer decision variables, which constitute the majority of the decision variables in the transit scheduling problem; and (ii) allow procedure-based declarations, thereby allowing complex algorithmic approaches (involving if then-else conditions) to be handled easily. The paper also shows how easily the same GA procedure with minimal modifications can handle a number of other more pragmatic extensions to the simple transit scheduling problem: buses with limited capacity, buses that do not arrive exactly as per scheduled times, and a multiple-station transit system having common routes among bus stations. Simulation results show the success of GAs in all these problems and suggest the application of GAs in more complex scheduling problems.
The Simple Genetic Algorithm and the Walsh Transform: Part I, Theory
Authors: Vose Michael D. , Wright Alden H.
Published: February 2008

This paper is the first part of a two-part series. It proves a number of direct relationships between the Fourier transform and the simple genetic algorithm. (For a binary representation, the Walsh transform is the Fourier transform.) The results are of a theoretical nature and are based on the analysis of mutation and crossover. The Fourier transform of the mixing matrix is shown to be sparse. An explicit formula is given for the spectrum of the differential of the mixing transformation. By using the Fourier representation and the fast Fourier transform, one generation of the infinite population simple genetic algorithm can be computed in time O(cl log2 3), where c is arity of the alphabet and l is the string length. This is in contrast to the time of O(c3l) for the algorithm as represented in the standard basis. There are two orthogonal decompositions of population space that are invariant under mixing. The sequel to this paper will apply the basic theoretical results obtained here to inverse problems and asymptotic behavior.
ptGAs—Genetic Algorithms Evolving Noncoding Segments by Means of Promoter/Terminator Sequences
Authors: Mayer Helmut A.
Published: February 2008

In this article we present work on chromosome structures for genetic algorithms (GAs) based on biological principles. Mainly, the influence of noncoding segments on GA behavior and performance is investigated. We compare representations with noncoding sequences at predefined, fixed locations with “junk” code induced by the use of promoter/terminator sequences (ptGAs) that define start and end of a coding sequence, respectively. AS one of the advantages of noncoding segments a few researchers have identified the reduction of the disruptive effects of crossover, and we solidify this argument by a formal analysis of crossover disruption probabilities for noncoding segments at fixed locations. The additional use of promoter/terminator sequences not only enables evolution of parameter values, but also allows for adaptation of number, size, and location of genes (problem parameters) on an artificial chromosome. Randomly generated chromosomes of fixed length carry different numbers of promoter/terminator sequences resulting in genes of varying size and location. Evolution of these ptGA chromosomes drives the number of parameters and their values to (sub)optimal solutions. Moreover, the formation of tightly linked building blocks is enhanced by self-organization of gene locations. We also introduce a new, nondisruptive crossover operator emerging from the ptGA gene structure with adaptive crossover rate, location, and number of crossover sites. For experimental comparisons of this genetic operator to conventional crossover in GAs, as well as properties of different ptGA chromosome structures, an artificial problem from the literature is utilized. Finally, the potential of ptGA is demonstrated on an NP-complete combinatorial optimization problem.
Evolutionary Algorithms, Homomorphous Mappings, and Constrained Parameter Optimization
Authors: Koziel Slawomir , Michalewicz Zbigniew
Published: February 2008

During the last five years, several methods have been proposed for handling nonlinear constraints using evolutionary algorithms (EAs) for numerical optimization problems. Recent survey papers classify these methods into four categories: preservation of feasibility, penalty functions, searching for feasibility, and other hybrids.

In this paper we investigate a new approach for solving constrained numerical optimization problems which incorporates a homomorphous mapping between n-dimensional cube and a feasible search space. This approach constitutes an example of the fifth decoder-based category of constraint handling techniques. We demonstrate the power of this new approach on several test cases and discuss its further potential.
Linkage Identification by Non-monotonicity Detection for Overlapping Functions
Authors: Munetomo Masaharu , Goldberg David E.
Published: February 2008

This paper presents the linkage identification by non-monotonicity detection (LIMD) procedure and its extension for overlapping functions by introducing the tightness detection (TD) procedure. The LIMD identifies linkage groups directly by performing order-2 simultaneous perturbations on a pair of loci to detect monotonicity/non-monotonicity of fitness changes. The LIMD can identify linkage groups with at most order of k when it is applied to O(2k) strings. The TD procedure calculates tightness of linkage between a pair of loci based on the linkage groups obtained by the LIMD. By removing loci with weak tightness from linkage groups, correct linkage groups are obtained for overlapping functions, which were considered difficult for linkage identification procedures.
An Electrophysiological Probe of Incidental Semantic Association
Authors: Kutas Marta , Hillyard Steven A.
Published: February 2008

Long-latency components of event-related brain potentials (ERPs) recorded from subjects reading meaningful text are sensitive to semantic relationships among the major lexical items of sentences. In particular, the N400 components are enlarged to words that are semantically unrelated to or incongruous with the context provided by preceding items in a sentence. The present experiment was aimed at finding out whether this inverse relationship between N400 amplitude and semantic association would extend to situations where words were presented in isolated pairs, using a design that dissociated changes in N400 from confounding ERP waves elicited by active decision making. KRP's were recorded to 320 word pairs presented to eleven subjects. Each pair of words was followed by a letter, and subjects made a differential response according to whether or not the letter had been present in either of the words. After the ERP recording session, subjects rated the degree of semantic association between the words in each pair. ERP averages were formed on the basis of the subjects' ratings and on the basis of normative, a priori categories. For both types of averages the N400 amplitude was found to be a sensitive index of semantic association, even though the association was incidental to the subject's assigned task. These findings suggest the utility of the N400 measure in studies of semantic priming and as a probe of the automaticity of contextual influences in language processing.
Indelibility of Subcortical Emotional Memories
Authors: LeDoux Joseph E. , Romanski Lizabeth , Xagoraris Andrew
Published: February 2008

Acquisition and extinction of fear responses conditioned to a visual stimulus were examined in rats with ablations of visual cortex. Visual cortex lesions did not interfere with acquisition, indicating that visual fear conditioning, like auditory fear conditioning, is mediated by sub-cortical, probably thalamo-amygdala, sensory pathways. In contrast to acquisition, extinction was greatly prolonged, if not prevented, by cortical ablation. This resistance to extinction of sub cortical emotional memories may explain certain aspects of emotional memory in man.
Global Versus Local Processing in the Absence of Low Spatial Frequencies
Authors: Hughes H. C. , Fendrich R. , Reuter-Lorenz P. A.
Published: February 2008

When observers are presented with hierarchical visual stimuli that contain incongruous coarse (“global”) and fine (“local”) pattern attributes, the global structure interferes with local pattern processing more than local structure interferes with global pattern processing. This effect is referred to as “global precedence.” The present experiments tested the hypothesis that global precedence depends on the presence of low spatial frequencies using stimuli constructed from “contrast balanced dots.” Stimuli composed of contrast balanced dots are largely devoid of low-frequency content. Choice reaction time to identify either the local or global pattern information was the dependent measure. Global precedence was found only for control stimuli that contained low spatial frequencies. In the absence of low-frequency information, local precedence was obtained. These findings suggest that global precedence is heavily dependent on the low spatial frequency content of the patterns.
Event-Related Potentials to Infrequent Changes in Synthesized Phonetic Stimuli
Authors: Sams Mikko , Aulanko Reijo , Aaltonen Olli , Näätänen Risto
Published: February 2008

Event-related potentials (ERPs) to synthetic consonant–vowel syllables were recorded. Infrequent changes in such a syllable elicited a "mismatch negativity" as well as an enhanced N100 component of the ERP even when subjects did not pay attention to the stimuli. Both components are probably generated in the supratemporal auditory cortex suggesting that in these areas there are neural networks that are automatically activated by speech-specific auditory stimulus features such as formant transitions.
Anterior Frontal Cortex and the Effect of Proactive Interference in Paired Associate Learning: A DC Potential Study
Authors: Uhl F. , Franzen P. , Serles W. , Lang W. , Lindinger G. , Deecke L.
Published: February 2008

This contribution focuses on neurophysiological correlates of the cerebral processes subserving the control of proactive interference. Event-related negative shifts of the scalp-recorded cortical steady potential (negative DC shifts) were measured in 17 right-handed normals during two tasks of paired associate learning. The control condition was a standard word pair learning task in which unrelated word pairs were presented. In the experimental condition, proactive interference was maximized by presenting very similar words and by requiring negative transfer, i.e., by having them reappear, but in different pairings. Proactive interference leads to increased anterior frontal negative DC shifts. Furthermore, centrotemporal negative DC shifts predicted subsequent cued recall performance. In spite of elaborative strategies, an effect of subsequent mnestic performance on the P300 was observed.
Deformable Templates for Face Recognition
Authors: Yuille Alan L.
Published: February 2008

We describe an approach for extracting facial features from images and for determining the spatial organization between these features using the concept of a deformable template. This is a parameterized geometric model of the object to be recognized together with a measure of how well it fits the image data. Variations in the parameters correspond to allowable deformations of the object and can be specified by a probabilistic model. After the extraction stage the parameters of the deformable template can be used for object description and recognition.