bluuebunny/crossref_metadata_2025 huggingface dataset:
The Stairway: A Novel Behavioral Test Detecting Sensomotoric Stroke Deficits in Rats
Authors: Boltze Johannes , Kowalski Ina , Förschler Annette , Schmidt Uwe , Wagner Daniel , Lobsien Donald , Emmrich Julius , Egger Dietmar , Kamprad Manja , Blunk James , Emmrich Frank
Published: October 2006

Abstract:  New therapeutic concepts of cell and tissue replacement therapies have been introduced in treatment of neurological disorders which require robust and sensitive sensomotoric behavioral diagnostic test systems for experimental research. However, most test arrays available are either expensive and/or sensitive to environmental disturbances. Moreover, an extensive training phase for experimental animals is often required by conventional tests to get reproducible data. In this study, we describe a new test array, the Stairway, that is robust, cost‐effective, and needs only a minimum training phase. Its efficiency is evaluated in comparison to the well‐established RotaRod and modified neurological severity score. Stroke was induced by middle cerebral artery occlusion. Human umbilical cord blood transplantation (n = 18) was performed 24 h after stroke by intravenous injection of suspended cells in comparison to control injections (n = 18), while behavioral assessment was carried out continuously for 29 days. Furthermore, development of lesions was monitored by magnetic resonance imaging. The results reveal the Stairway test as a simple, highly reproducible, and easy manageable test system thus reflecting therapeutic benefits precisely.
Bone Engineering: Combining Smart Biomaterials and the Application of Stem Cells
Authors: Lechner Sarah , Huss Ralf
Published: October 2006

Abstract:  Remarkable preclinical progress and achievements in the isolation and characterization of stem cells from different sources have been made, together with the ability to control proliferation and differentiation in vitro. Researchers and physicians pin their hope on stem cells to develop novel approaches in regenerative medicine. Stem cell therapy is no longer a scientific discipline in the laboratory or in animal models only, as it is already performed routinely in the human therapeutical and clinical treatment for hematological malignancies and clinical trials for bone repair. It has further been recognized that angiogenesis plays a pivotal role for the successful transplantation of in vitro engineered tissues like bone structures, for the repair of large bone defects to facilitate engraftment. We intended to generate transplantable composite grafts, which consist of in vitro generated bone tissue from multipotent adult progenitor cells, maintaining an angiogenic potential to ease and optimize a successful engraftment of long‐term sustainable and viable bone tissue. The other component was generated from several synthetically produced three‐dimensional tissues like fibrin, thrombin, collagen, hydroxyapatite, and β‐tricalciumphosphate in different compositions and concentrations, all mimicking natural body structures of bone tissue as biocompatible grafts. We established an in vitro mouse model, using bone marrow and peripheral blood‐derived murine progenitor cells as well as industrially manufactured materials generating composite grafts. Based on our preliminary results, we propose to pursue research on composite grafts for an extended graft survival and successful engraftment of transplanted tissue.
A Human Lymph Node In Vitro—Challenges and Progress
Authors: Giese Christoph , Demmler Christian D. , Ammer Richard , Hartmann Stefan , Lubitz Annika , Miller Lilja , Müller Riccarda , Marx Uwe
Published: October 2006

Abstract:  Extracorporeal human lymphatic organs are expected to be excellent tools in the study of human molecular and cellular bases of the immunologic balance and tissue harmony. A rational approach and process to design a device and a procedure to recreate the human lymph node environment in vitro is described with emphasis on T‐cell activation. Based on this approach, a bioreactor and a process supporting self‐assembly of human lymphatic tissues due to proper emulation of human architecture and homeostasis could be developed.
Sleep and Headache Disorders: Clinical Recommendations for Headache Management
Authors: Rains Jeanetta C. , Poceta J. Steven
Published: October 2006

Clinical practice points were drawn from a review of sleep and headache disorders published in the regular issue of Headache (released in tandem with this supplement). The recommendations include: (1) Sleep as well as psychiatric disorders tend to become prevalent in more complex and severe headache patterns and regulation of sleep and mood may favorably impact headache threshold; (2) Specific headache patterns, irrespective of headache diagnosis, are suggestive of a potential sleep disorder (eg, “awakening” or morning headache, chronic daily headache); (3) Sleep disorders most implicated with headache include obstructive sleep apnea, primary insomnia, and circadian phase abnormalities, and treatment of such sleep disorders may improve or resolve headache; (4) Inexpensive screening tools (eg, sleep history interview, headache/sleep diary, validated questionnaires, prediction equations) aid identification of patients warranting polysomnography; and (5) Pharmacologic and behavioral therapies are effective in the regulation of sleep and are compatible with usual headache care.
“Are You Talking to Me?” Confronting Behavioral Disturbances in Patients With Headache
Authors: Saper Joel R.
Published: October 2006

The famous question, “Are you talking to me?,” was coined by Robert DeNiro in his lead role as Travis Bickle in the Martin Scorsese classic, Taxi Driver. The phrase also characterizes the troubling encounters that many headache‐treating professionals confront as they attempt to discuss serious matters of care and compliance with some of their headache patients. Although most headache patients are eager to take professional advice and guidance, there exists a minority of patients whose behavior undermines a collaborative relationship between doctor and patient. In these cases, the physician may need to directly confront this behavior in order to overcome behavioral barriers that interfere with desirable treatment outcomes. This article offers explicit means and strategies to engage difficult patients, increase the likelihood of program adherence and improvement, and develop a more satisfying doctor‐patient relationship, based on clinical experience in a national referral center for difficult‐to‐manage headache patients.
Elementary Grade Retention in Texas and Reading Achievement Among Racial Groups: 1994–2002
Authors: Lorence Jon , Dworkin Anthony Gary
Published: October 2006

Students who failed the Texas mandatory third grade reading test were followed through their sophomore year in high school. Comparisons of reading scores between third grade students who repeated the grade and their socially promoted classmates revealed that the positive effect of retention persisted over time. Retention in third grade benefited low‐performing readers regardless of race. Supplemental analyses found that the results are not likely attributable to selection biases, differential attrition of students from the panel, changes in the special education status of students, and regression to the mean effects. Making students repeat a grade, when supplemented with additional educational assistance, can benefit academically challenged children.
Allergic contact dermatitis to copolymers in cosmetics – case report and review of the literature
Authors: Quartier Sarah , Garmyn Marjan , Becart Sophie , Goossens An
Published: October 2006

Copolymers or heteropolymers are large molecules with high molecular weights (>1000 D). They have been underestimated for a long time as to their sensitizing capacities. Allergic contact dermatitis to 6 copolymers in cosmetics and 1 in a medical dressing has been described; however, the nature of the hapten is still unknown. We report a case of allergic contact dermatitis to polyvinylpyrrolidone (PVP)/hexadecene copolymer in a purple‐colored lipstick and review the literature on allergic contact dermatitis to 7 copolymers: PVP/hexadecene, PVP/eicosene, PVP/1‐triacontene, methoxy polyethyleneglycol (PEG)‐22/dodecyl glycols, methoxy PEG‐17/dodecyl glycols, phthalic anhydride/trimellitic anhydride/glycols, and polyvinyl methyl/maleic acid anhydride.
Generalized livedo reticularis associated with monoclonal cryoglobulinemia and multiple myeloma
Authors: Requena Luis , Kutzner Heinz , Angulo Jorge , Renedo Guadalupe
Published: October 2006

Abstract:  Cryoglobulins are detected in a wide variety of diseases, including malignancies, infections and systemic autoimmune diseases. Classically, monoclonal cryoglobulinemia is associated with hematologic malignancies, whereas mixed cryoglobulinemias are reported in association with hepatitis C virus infections or autoimmune diseases. We present a patient with generalized livedo reticularis as the first manifestation of monoclonal cryoglobulinemia and multiple myeloma. Histopathology demonstrated that nearly all small blood vessels of the upper and deep dermis, as well as the capillaries of the fat lobule, were filled with homogeneous, eosinophilic material that corresponded to monoclonal cryoglobulin deposits within the vascular lumina. Our case of livedo reticularis associated with monoclonal cryoglobulinemia and multiple myeloma was exceptional, because the mottled cyanotic discoloration of the skin with a reticular pattern was generalized, covering most of the skin surface. We have not found previous report of similar cases. Therefore, we recommend that dermatologists be made aware of the significance of this diagnosis.
Chronic arsenic poisoning: a global health issue – a report of multiple primary cancers
Authors: Walvekar R. R. , Kane S. V. , Nadkarni M. S. , Bagwan I. N. , Chaukar D. A. , D’Cruz A. K.
Published: October 2006

Abstract:  Chronic arsenic (As) poisoning is a worldwide public health problem. Effects of prolonged exposure to high levels of As in drinking water have been observed and documented in various epidemiological studies from all over the world. The non‐malignant cutaneous effects of chronic exposure to inorganic As are well known. A case presenting with multiple cutaneous cancers as well as an internal lung primary in a patient exposed to toxic levels of As in the drinking water is discussed along with a review of literature.
Cutaneous granular cell tumor with epidermal involvement: a potential mimic of melanocytic neoplasia
Authors: Ray Sourav , Jukic Drazen M.
Published: October 2006

Background:  Cutaneous granular cell tumor (GCT) may present with extension into the junctional region of the epidermis and thus may mimic melanocytic neoplasms.

Methods:  We reviewed three cases of cutaneous GCT where a melanocytic neoplasm was either initially diagnosed or considered in the differential diagnosis. Histopathology was evaluated in regards to features associated with melanocytic neoplasms. Immunohistochemistry was performed to delineate a panel useful in the distinction of these and other entities.

Results:  All cases consisted of spindle and epithelioid cells with granular cytoplasm and bland nuclei and were centered in the superficial dermis with extension into the epidermis. Two cases resembled Spitz nevi and one case demonstrated lentiginous growth. All cases stained positively with calretinin and inhibin. Two of the three cases stained diffusely with S100 and 2/2 cases with CD56. HAM56 and CD68 were positive in one case and another showed positivity for NSE and PGP9.5. HMB‐45, tyrosinase, and Melan‐A were non‐reactive in all cases tested.

Conclusions:  GCT may involve the epidermis and has a growth pattern similar to melanocytic neoplasms. An immunohistochemical (IHC) panel including S100, Melan‐A, tyrosinase, HMB‐45, CD56, CD68, calretinin, inhibin, and PGP9.5 may aid in the distinction and may spare the patient from unnecessary morbidity.
Reduced expression of the antiapoptotic proteins of Bcl‐2 gene family in the lesional epidermis of patients with Darier’s disease
Authors: Pasmatzi Efi , Badavanis George , Monastirli Alexandra , Tsambaos Dionysios
Published: October 2006

Background:  Dyskeratotic cells in Darier’s disease (DD) are thought to represent apoptotic keratinocytes. Bcl‐2 gene family proteins play a major role in the regulation of apoptosis of epidermal keratinocytes and reveal pleiotropic interactions with intracellular Ca2+ homeostasis. The latter is impaired in DD because of mutations of ATP2A2 gene that encodes the type 2 isoforms of the sarcoplasmic/endoplasmic reticulum (ER) Ca++ ATPase 2 (SERCA2) pump.

Methods:  The expression of Bcl‐2, Bax, and Bcl‐xL proteins was investigated in the epidermis of 11 patients with DD and of 11 sex‐ and age‐matched healthy controls by immunohistochemistry.

Results:  The expression of Bcl‐2 and Bcl‐xL was clearly reduced in the lesional epidermis of the patients, as compared with the normal epidermis of healthy controls, whereas the expression of Bax remained unaltered.

Conclusions:  The alterations in the expression of Bcl‐2 gene family proteins could be a crucial event for the activation of the apoptotic process in the lesional epidermis of DD patients and for the occurrence of the characteristic dyskeratotic keratinocytes. The question as to whether these alterations are associated with the ER Ca2+ depletion in DD or represent secondary phenomena unrelated to the genetic defect of this genodermatosis remains to be elucidated.
Keep the Traffic Moving: Mechanism of the Hsp70 Motor
Authors: Sousa Rui , Lafer Eileen M.
Published: October 2006

Hsp70s are ubiquitous chaperones that use ATP hydrolysis to drive a variety of protein processing reactions, including a number of steps in protein trafficking. Recent studies have shed light on how ATP might generate conformational changes in an Hsp70 molecule and how such changes might be harnessed to drive processes as diverse as protein import into subcellular organelles and uncoating of clathrin‐coated vesicles.
Knowledge of general practitioners dentists about the emergency management of dental avulsion in Curitiba, Brazil
Authors: Westphalen Vania Portela Ditzel , Martins Wilson Denis , Deonizio Marili Doro Andrade , Da Silva Neto Ulisses Xavier , Da Cunha Camila Bezerra , Fariniuk Luis Fernando
Published: October 2006

Abstract –  The prognosis of traumatized teeth in general and of avulsed teeth in particular depends on prompt and appropriate treatment. Management of traumatic injuries may be a challenge to the non‐specialized dentist, as they may occur when dentists are least prepared for it. The objective of this research was to investigate the knowledge of general practitioner dentists about the emergency management of dental avulsion in Curitiba, PR, Brazil. A group of 250 professionals were interviewed. The questions were related to knowledge of how to treat traumatic avulsion of teeth. The results suggest that the level of knowledge on the management of dental avulsion of the general practitioners dentists in Curitiba is adequate.
Use of hydroxyapatite in tooth replantation radiographically followed up for 14 years: a case report
Authors: Baldissera Elaine de Fátima Zanchin , Fontanella Vania Regina , Ito Wilson , Pomar Fernando
Published: October 2006

Abstract –  A lateral incisor was replanted 4 h after trauma. The tooth subsequently developed external root resorption treated with calcium hydroxide initially and with a hydroxyapatite root filling subsequently. Radiographs of the replanted tooth were obtained to follow up the patient for 14 years.
Supplementary effect of peppermint (Mentha × piperita) on dry matter intake, digestibility, ruminal fermentation and milk production in early lactating dairy cows
Authors: HOSODA Kenji , MATSUYAMA Hiroki , PARK Woong‐Yeoul , NISHIDA Takehiro , ISHIDA Motohiko
Published: October 2006

The aim of this research was to investigate the effect of peppermint feeding on dry matter intake, nutrient digestibility, ruminal fermentation and milk production in early lactating cows. Four Holstein cows were offered a diet with 5% dried peppermint and four Holstein cows remained on a diet without 5% of dried peppermint on a dry matter basis. The addition of peppermint to feed did not affect dry matter intake, although the eating time of feed was increased by mixing the feed with peppermint. There were no significant differences in the nutrient digestibilities between the two treatments. The ruminal ammonia and volatile fatty acids concentrations were similar in the two treatments, however, peppermint ingestion by cows led to a decrease in ruminal pH. The lowered pH value was within the stable pH condition range. No significant differences in the treatments were observed in milk production or milk composition except for the milk fat content. These results suggest that feeding peppermint to early lactating cows had little effect on their dry matter intake, nutrient digestibility, ruminal fermentation and milk production.
Variations of blood corpuscles and immunoglobulin G of plasma and milk in placenta‐fed sows
Authors: LEE Sung‐Dae , SONODA Tatsunobu , HASEGAWA Nobumi , FUKUNAGA Rie , HARADA Hiroshi , SONG Young‐Min , HIDAKA Ryoichi
Published: October 2006

The objective of the present study was to investigate the variations of blood corpuscle and immunoglobulin G (IgG) of plasma and milk in sows fed placenta. The first experiment was designed with two groups, the experimental group (Ex: with placenta) and the control (Ct: without placenta) depending on whether they were fed placenta or not. The second experiment was designed using varying condition of placenta (fresh: Fp or cooked: Cp) and amounts of placenta (900 g or 1800 g) according to 2 × 2 factorial design. The number of erythrocytes were higher (P < 0.05) in Ct than in Ex on day 1 of Experiment 1. It was greater in Fp than in Cp on day 3 (P < 0.01) and day 8 (P < 0.05) in Experiment 2. The concentration of hemoglobin was greater (P < 0.05) in Fp than in Cp on day 3 in Experiment 2. In Experiment 1, the concentration of IgG in milk was significantly greater in Ex than in Ct on day 15 (P < 0.05) and day 20 (P < 0.01). In Experiment 2, the concentration of IgG in plasma was significantly greater in Fp than in Cp from day 3 to day 20 (P < 0.05). The concentration of IgG in milk was greater (P < 0.05) in Fp than in Cp on day 1 in Experiment 2. The results indicate that, when supplied as a feed, fresh placenta affected the IgG in the plasma and milk of sows.
A simple null model predicts fruit‐frugivore interactions in a temperate rainforest
Authors: Burns K. C.
Published: October 2006

Studies of seed dispersal mutualisms typically test for adaptive relationships between fruits and frugivores. Here, I take the opposite approach, and ask what relationships would be expected based on chance encounters between mutualists. I derived a simple null model to predict pair‐wise relationships between fruit and frugivore species. I assumed that all frugivores had identical fruit preferences, but allowed for interspecific variation in plant abundances, frugivore abundances and fruit phenologies. Under these conditions, the number of visits each frugivore species makes to each plant species results from the product of plant abundances and frugivore abundances when each plant species produces fruit. I then tested null model predictions with observations in a temperate rainforest in British Columbia, Canada. I measured the abundance and phenology of seven bird‐dispersed plant species, seasonal changes in the abundances of six avian frugivore species and 212 interactions between them. Empirical results were generally consistent with predictions, suggesting that relationships between birds and fruits are structured randomly. However, some variation in relationships between observations and predictions was observed, suggesting deterministic processes may also be important. Overall results illustrate that predictable relationships between fruit and frugivore species can result from random encounters between mutualists.
Assessing impacts of ecosystem engineers on community organization: a general approach illustrated by effects of a high‐Andean cushion plant
Authors: I. Badano Ernesto , G. Jones Clive , A. Cavieres Lohengrin , P. Wright Justin
Published: October 2006

Comparative and integrative tools are of fundamental value in ecology for understanding outcomes of biological processes, and making generalizations and predictions. Although ecosystem engineering has been shown to play a fundamental role in community organization, there are no standardized methods to measure such effects. We present a framework and methodology for assessing the impact of physical ecosystem engineers on three general features of community organization: (1) species richness and composition, (2) stability of richness over time, and (3) dominance patterns of species assemblages. We then apply the framework and methodology to assess the effects of the cushion plantAzorella monanthaon high‐Andean plant communities on two mountaintops. Substrate temperatures, soil moisture and the availability of mineral nutrient resources were compared betweenA. monanthaand surrounding open areas to ascertain whether cushions altered abiotic environmental conditions, while community analysis assessed changes in species richness, composition and abundances at patch and landscape levels. Cushions thermally buffered temperature extremes and increased soil moisture, but had no detectable effect on soil mineral nutrients. Cushion habitat was not more species rich than surrounding areas, but cushions added new species into the community, altering species composition and markedly enhancing landscape‐level richness. Cushions also showed potential for stabilizing species richness over time, and changed patterns of species dominance. Findings were consistent across mountaintops. We evaluate the general utility of the framework and call for its application in other systems as a means to generate comparative data sets for assessing the general effects of ecosystem engineers on community organization.
Ploidy level interacts with population size and habitat conditions to determine the degree of herbivory damage in plant populations
Authors: Münzbergová Zuzana
Published: October 2006

Recently it has been suggested that ploidy level of a plant population may have important effects on plant‐animal interactions. Plant‐animal interactions can also be strongly altered by factors such as plant population size and habitat conditions. It is, however, not known how these factors interact to shape the overall pattern of plant‐animal interactions.

I studied the interaction between a perennial plant, Aster amellus, and a monophagous herbivorous moth, Coleophora obscenella, and investigated the effect of ploidy level of the plant population, plant population size, isolation and habitat conditions on density of the insect, damage by the insect, and plant performance.

Ploidy level, plant population size and habitat conditions, but not isolation, strongly influence plant‐herbivore interactions. Furthermore, there are significant interactions between effects of ploidy level and plant population size and between ploidy level and isolation. Hexaploid plants suffer higher seed damage by the herbivore, but their seed production is still higher than that of diploids. Herbivores thus partly limit the evolutionary success of the hexaploid plants. Plant‐animal interactions are also strongly determined by plant population size. Small populations of A. amellus (below forty flowering ramets) host no C. obscenella larvae, indicating a minimum A. amellus population size that can sustain a viable C. obscenella population. Negative and positive effects of plant population size balance and result in no relationship between plant population size and number of developed seeds per flower head. The results also show a significant interaction between ploidy level and plant population size, indicating that the increase in density of C. obscenella larvae with plant population size is greater in hexaploid than in diploid populations. The results also indicate that the effect of ploidy level on plant‐herbivore interactions can be altered by plant population size, which suggests that plant‐herbivore interactions are driven by a complex of interactions among different factors. Studying each factor separately could thus lead to biased conclusions about patterns of interactions in such systems.
Kinematics and eye–head coordination of gaze shifts evoked from different sites in the superior colliculus of the cat
Authors: Guillaume Alain , Pélisson Denis
Published: October 2006

Shifting gaze requires precise coordination of eye and head movements. It is clear that the superior colliculus (SC) is involved with saccadic gaze shifts. Here we investigate its role in controlling both eye and head movements during gaze shifts. Gaze shifts of the same amplitude can be evoked from different SC sites by controlled electrical microstimulation. To describe how the SC coordinates the eye and the head, we compare the characteristics of these amplitude‐matched gaze shifts evoked from different SC sites. We show that matched amplitude gaze shifts elicited from progressively more caudal sites are progressively slower and associated with a greater head contribution. Stimulation at more caudal SC sites decreased the peak velocity of the eye but not of the head, suggesting that the lower peak gaze velocity for the caudal sites is due to the increased contribution of the slower‐moving head. Eye–head coordination across the SC motor map is also indicated by the relative latencies of the eye and head movements. For some amplitudes of gaze shift, rostral stimulation evoked eye movement before head movement, whereas this reversed with caudal stimulation, which caused the head to move before the eyes. These results show that gaze shifts of similar amplitude evoked from different SC sites are produced with different kinematics and coordination of eye and head movements. In other words, gaze shifts evoked from different SC sites follow different amplitude–velocity curves, with different eye–head contributions. These findings shed light on mechanisms used by the central nervous system to translate a high‐level motor representation (a desired gaze displacement on the SC map) into motor commands appropriate for the involved body segments (the eye and the head).
Effects of flecainide and quinidine on arrhythmogenic properties ofScn5a+/Δ murine hearts modelling long QT syndrome 3
Authors: Stokoe Kate S. , Thomas Glyn , Goddard Catharine A. , Colledge William H. , Grace Andrew A. , Huang Christopher L.‐H.
Published: October 2006

Long QT(3) (LQT3) syndrome is associated with incomplete Na+channel inactivation, abnormal repolarization kinetics and prolonged cardiac action potential duration (APD). Electrophysiological effects of flecainide and quinidine were compared in Langendorff‐perfused wild‐type (WT), and genetically modified (Scn5a+/Δ) murine hearts modelling LQT3. Extra stimuli (S2) following trains of pacing stimuli (S1) applied to the right ventricular epicardium triggered ventricular tachycardia (VT) in 16 out of 28 untreatedScn5a+/Δ and zero out of 12 WT hearts. Paced electrogram fractionation analysis then demonstrated increased electrogram durations (EGD), expressed as EGD ratios, in arrhythmogenicScn5a+/Δ hearts, and prolonged ventricular effective refractory periods in initially non‐arrhythmogenicScn5a+/Δ hearts. Nevertheless, comparisons of epicardial and endocardial monophasic action potential recordings demonstrated negative transmural repolarization gradients in both groups, giving ΔAPD90values at 90% repolarization of −20.88 ± 1.93 ms (n= 11) and −16.91 ± 1.43 ms (n= 23), respectively. Flecainide prevented initiation of VT in 13 out of 16 arrhythmogenicScn5a+/Δ hearts, reducing EGD ratio and restoring ΔAPD90to + 7.55 ± 2.24 ms (n= 9) (P< 0.05). VT occurred in four out of eight non‐arrhythmogenicScn5a+/Δ hearts in the presence of quinidine, which increased EGD ratio but left ΔAPD90unchanged. In contrast (P< 0.05), WT hearts had positive ΔAPD90values (+ 11.72 ± 2.17 ms) (n= 20). Flecainide then increased arrhythmic tendency and EGD ratio but conserved ΔAPD90; reduced EGD ratios and unaltered ΔAPD90values accompanied the lower arrhythmogenicity associated with quinidine treatment. In addition to the changes in EGD ratio shown by WT hearts, these findings attribute arrhythmogenesis and its modification by flecainide and quinidine to alterations in ΔAPD90inScn5a+/Δ hearts. This is consistent with a hypothesis in which incomplete Na+channel inactivation inScn5a+/Δ hearts generates functional substrates dependent on altered refractoriness that cause abnormalities in activation and conduction of subsequent cardiac impulses. Any spatial heterogeneities between the epicardial and endocardial layers would thus cause fragmentation of the activation wavefront and contribute to electrogram spreading.
Extrasynaptic αβ subunit GABAA receptors on rat hippocampal pyramidal neurons
Authors: Mortensen Martin , Smart Trevor G.
Published: October 2006

Extrasynaptic GABAA receptors that are tonically activated by ambient GABA are important for controlling neuronal excitability. In hippocampal pyramidal neurons, the subunit composition of these extrasynaptic receptors may include α5βγ and/or α4βδ subunits. Our present studies reveal that a component of the tonic current in the hippocampus is highly sensitive to inhibition by Zn2+. This component is probably not mediated by either α5βγ or α4βδ receptors, but might be explained by the presence of αβ isoforms. Using patch‐clamp recording from pyramidal neurons, a small tonic current measured in the absence of exogenous GABA exhibited both high and low sensitivity to Zn2+ inhibition (IC50 values, 1.89 and 223 μm, respectively). Using low nanomolar and micromolar GABA concentrations to replicate tonic currents, we identified two components that are mediated by benzodiazepine‐sensitive and ‐insensitive receptors. The latter indicated that extrasynaptic GABAA receptors exist that are devoid of γ2 subunits. To distinguish whether the benzodiazepine‐insensitive receptors were αβ or αβδ isoforms, we used single‐channel recording. Expressing recombinant α1β3γ2, α5β3γ2, α4β3δ and α1β3 receptors in human embryonic kidney (HEK) or mouse fibroblast (Ltk) cells, revealed similar openings with high main conductances (∼25–28 pS) for γ2 or δ subunit‐containing receptors whereas αβ receptors were characterized by a lower main conductance state (∼11 pS). Recording from pyramidal cell somata revealed a similar range of channel conductances, indicative of a mixture of GABAA receptors in the extrasynaptic membrane. The lowest conductance state (∼11 pS) was the most sensitive to Zn2+ inhibition in accord with the presence of αβ receptors. This receptor type is estimated to account for up to 10% of all extrasynaptic GABAA receptors on hippocampal pyramidal neurons.
Hopf-Hopf Interactions of Surge and Rotating Stall
Authors: Coller B. D.
Published: October 2006

In this paper, we examine the interaction of two instabilities that occur in axial compressors using the Hopf-Hopf normal form. As a result, we illuminate some gaps in understanding the dynamics of standard compressor models. We find a possible dynamic mechanism, which explains certain “curious” behavior observed in experiments, and are able to predict and explain failure mechanisms in previously proposed control strategies.
A Simple Stabilizing Control for Sagittal Plane Locomotion
Authors: Schmitt John
Published: October 2006

The spring loaded inverted pendulum model has been shown to accurately model sagittal plane locomotion for a variety of legged animals and has been used as a target for control for higher dimensional robotic implementations. Tuned appropriately, the model exhibits passively stable periodic gaits using either fixed leg touch-down angle or swing-leg retraction leg touch-down protocols. In this work, we examine the performance of the model when model parameters are set to values characteristic of an insect, in particular the cockroach Blaberus discoidalis. While body motions and forces exhibited during a stride are shown to compare well with those observed experimentally, almost all of the resulting periodic gaits are unstable. We therefore develop and analyze a simple adaptive control scheme that improves periodic gait stability properties. Since it is unlikely that neural reflexes can act quickly enough during a stride to effect control, control is applied once per stance phase through appropriate choice of the leg touch-down angle. The control law developed is novel since it achieves gait stabilization solely through a judicious combination of leg lift-off and touch-down angles, instead of utilizing all of the system positions and velocities in full-state feedback control. Implementing the control law improves the stability properties of a large number of periodic gaits and enables movement between stable periodic gaits by changing a single parameter.
The Influence of G&H on Nonlinear Dynamics
Authors: Marsden Jerrold E.
Published: October 2006

This paper describes the place of the book by Guckenheimer and Holmes (Nonlinear Oscillations, Dynamical Systems and Bifurcations of Vector Fields, Springer-Verlag, Berlin, 1983) in the research and literature on nonlinear dynamics.
Actuators for Micropositioners and Nanopositioners
Authors: Hubbard Neal B. , Culpepper Martin L. , Howell Larry L.
Published: October 2006

A summary of recent research in micropositioning and nanopositioning is presented. The work is classified into five groups by actuation approach, including piezoelectric, magnetic, electrostatic, thermal, and electrochemical microactuators. A consistent set of measurable, key characteristics are proposed: degrees of freedom, range, resolution, range-to-resolution ratio, footprint, force, natural frequency, and bandwidth. Values of the key characteristics are listed in tables. The results demonstrate the boundaries of current knowledge and the advantages of each actuation approach. This is the first time this information has been compiled in this growing field and it is summarized in such a way as to be useful to readers. There are 82 references cited in this review article.
Synthesis and optical properties of ZnO–ZnS core-shell nanotube arrays
Authors: Liao Hung-Chou , Kuo Pai-Chia , Lin Chin-Ching , Chen San-Yuan
Published: October 2006

Heterostructured ZnO–ZnS core-shell nanotube arrays with the diameters of 50–80nm and lengths up to 1μm were synthesized by a two-step chemical reaction. First, the ZnO layer was grown by atomic-layer deposition. It was found that the preferred growth orientation was strongly dependent on the substrate temperature. After sulfuration conversion from arrayed ZnO nanorods, the ZnS–ZnO composite arrays can be successfully prepared, as evidenced from transmission electron microscopy. This confirms that the ZnO–ZnS core-shell nanotube-arrayed structure has been fabricated. X-ray photoelectron spectroscopy analysis indicates that the binding energy of S 2p is the same as that of bulk single-crystal ZnS and that the Zn 2p3∕2 peak is shifted about 0.5eV due to the formation of Zn–S bonds. Photoluminescence shows the relative-intensity ratio of ultraviolet emission (IUV) to deep-level emission (IDLE) for ZnO∕ZnS core-shell nanotubes can be enhanced to be nine times that of original ZnO nanotubes.
Influence of oxygen content on electrical properties of NiO films grown by rf reactive sputtering for resistive random-access memory applications
Authors: Park Jae-Wan , Park Jong-Wan , Jung Kyooho , Yang Min Kyu , Lee Jeon-Kook
Published: October 2006

NiO films were prepared on Pt∕Ti∕SiO2∕Si substrates by rf reactive sputtering. The voltage-current characteristics of the Pt∕NiO∕Pt structures showed reproducible resistive switching behaviors at room temperature. The high- and low-resistance states were retained without applying an external bias voltage; the high- to low-resistance ratio was greater than 10. To investigate the influence of the oxygen content on the electrical properties, voltage-current characteristics of NiO films grown at various oxygen contents were investigated. As oxygen content increased from 5% to 10%, the resistance value of the NiO film drastically increased, and a resistive switching behavior was observed. However, as the oxygen content increased to 20%, the resistive switching behavior disappeared. The change in switching behavior was discussed in terms of Ni vacancies and compensating holes inside the NiO film. In addition, the memory properties of NiO-based resistive random-access memory were also investigated.
Application of x-ray metrology in the characterization of metal gate thin films
Authors: Hung P. Y. , Alshareef Husam , Lafford Tamzin , Bowen D. Keith , Majhi Prashant , Diebold Alain
Published: October 2006

Physical characterization of as-deposited and 1000°C annealed TaxAl1−xN thin films was performed using several characterization techniques. X-ray diffraction metrology shows that the crystallographic phase and crystallinity of TaN and AlN films vary with composition. The unannealed TaN film was cubic TaN, while the annealed TaN was mixed hexagonal Ta2N and hexagonal TaN. Both AlN films were hexagonal, with the annealed film having a higher crystalline fraction. However, TaxAl1−xN films displayed a relatively small change in crystalline fraction and crystallography. Well behaved capacitors were fabricated, and a work function of ∼5.0eV was obtained.
Three-dimensional SU-8 structures by reversal UV imprint
Authors: Hu W. , Yang B. , Peng C. , Pang S. W.
Published: October 2006

In this work, three-dimensional (3D) SU-8 micro- and nanostructures were fabricated using a reversal UV imprint process at low temperature and low pressure. The SU-8 polymer was coated on a patterned glass mold and then transferred onto various substrates by reversal UV imprint at a typical temperature of 50°C, pressure of 1MPa, and UV exposure of 1s. The lower temperature and pressure used compared to conventional thermal imprint shorten the imprint time and alleviate pattern distortion. A combination of silanes was used to generate a medium surface energy on the imprint molds to enable polymer spin coating and mold release after imprint. In addition, an O2 plasma was used for glass mold treatment to improve uniformity of silane coating and to increase substrate surface energy for better polymer adhesion. Using this technology, 100nm–1μm wide SU-8 gratings were fabricated on flat or patterned substrates with good fidelity. By repeating this process, multiple-level nanochannels, cavities, or air-bridging polymer structures with 400nm–10μm widths have been demonstrated. The surface energy of SU-8 was modified using an O2 plasma to promote layer adhesion for 3D stacking. This reversal UV imprint technology offers versatility and flexibility to stack polymer layers and multiple-level sealed fluidic channels.
Laser ablation of via holes in GaN and AlGaN∕GaN high electron mobility transistor structures
Authors: Anderson Travis , Ren Fan , Pearton Stephen J. , Mastro Michael A. , Holm Ron T. , Henry Rich L. , Eddy Charles R. , Lee Joon Yeob , Lee Kwan-Young , Kim Jihyun
Published: October 2006

Laser drilling for through-via holes was performed with a Nd:YVO4 laser for an AlGaN∕GaN high electron mobility transistor (HEMT) structure on a SiC substrate. Current-voltage (I-V) characteristics, transconductance, and small signal characteristics before and after laser drilling were compared to examine the effect of laser drilling on device performance. The electrical characteristics of the HEMTs did not show significant change after laser drilling, even when performed in close proximity to the device. Laser drilling was found to be a fast and safe technique to drill via hole in AlGaN∕GaN HEMT structure and provides an alternative to dry etching for creation of these vias.
Nanoscale structure fabrication of multiple AlGaSb∕InGaSb quantum wells by reactive ion etching with chlorine-based gases toward photonic crystals
Authors: Gozu Shin-ichiro , Akahane Kouichi , Yamamoto Naokatsu , Ueta Akio , Ohtani Naoki , Tsuchiya Masahiro
Published: October 2006

The authors studied nanoscale structure fabrication of multiple AlGaSb∕InGaSb quantum wells. The fabrication was successfully conducted using simple resist masks for electron beam lithography and reactive ion etching (RIE) with chlorine-based gases. The etching profile after the RIE showed good vertical shape. Etching damage induced by the RIE was revealed by using photoluminescence measurements. The effects of surface recombination at the etching sidewalls were large, but the effects were suppressed by using HCl and (NH4)2Sx treatments. The damage was low enough to create small active optical devices, such as photonic crystals, comparably with current InGaAsP systems.
Optimization of a Cl2–H2 inductively coupled plasma etching process adapted to nonthermalized InP wafers for the realization of deep ridge heterostructures
Authors: Guilet S. , Bouchoule S. , Jany C. , Corr C. S. , Chabert P.
Published: October 2006

Inductively coupled plasma etching using Cl2–H2 chemistry with no additive gas (CH4, Ar, or N2) is studied to realize deep (>5μm) ridges with smooth and vertical sidewalls. The process is optimized for nonthermalized InP wafers to avoid the use of thermal grease. Cleaning of the rear side of the wafer after etching is avoided, which is suitable for an industrial process or for critical subsequent steps such as epitaxial regrowth. The influence of the Cl2∕H2 ratio on the etching mechanism is investigated for both InP bulk layers and InGaAs∕InP or InGaAlAs∕InP heterostructures. The authors show that this ratio is the main parameter controlling the ridge profile, in a similar way for both bulk InP and InGa(Al)As∕InP samples. Smooth and vertical sidewalls with neither undercuts nor notches can be obtained in the 0.5–1mT pressure range for a hydrogen percentage of 35%–45% in the gas mixture. Etching rates from 900to1300nm∕min together with a selectivity over SiNx dielectric mask as high as 24:1–29:1 are measured for the InP bulk layers under these conditions. Etching does not affect the optical quality of the heterostructures as evidenced from micro-photoluminescence measurements performed on 1.6-to0.85-μm-wide deep etched ridge waveguides. The process is well adapted to the realization of low loss deep ridge waveguides or buried heterostructures.
Swing effects in alternating phase shift mask lithography: Implications of low σ illumination
Authors: Singh Navab , Sun H. Q. , Foo W. H. , Mehta S. S. , Kumar R. , Adeyeye A. O. , Suda H. , Kubota T. , Kimura Y. , Kinoshita H.
Published: October 2006

We develop sub-100-nm resist patterns with alternating phase shift mask (alt PSM) using 0.68 numerical aperture KrF lithography scanner at a partial coherence factor σ of 0.31, the lowest available in our tool—a need of alt PSM technique. Although we achieve resist lines down to 65nm, the standing wave and critical dimension (CD) swing effects are immense on big patterns. The 180nm lines show CD swings two times to that of 90nm lines. The sidewall profiles of 180nm lines are also more susceptible to swing inflection point selection than 90nm lines. The finding on the use of alt PSM is that the higher standing wave, larger CD swing, and more degradation of sidewall profiles on big patterns than small patterns are the implications of low σ illumination. We suggest the inclusion of big patterns for swing studies while setting up the lithography process using alt PSM.
Novel nanoscale thermal property imaging technique: The 2ω method. II. Demonstration and comparison
Authors: Roh Hee Hwan , Lee Joon Sik , Kim Dong Lib , Park Jisang , Kim Kyeongtae , Kwon Ohmyoung , Park Seung Ho , Choi Young Ki , Majumdar Arun
Published: October 2006

This paper presents the 2ω method, a newly developed ac mode local thermal property imaging technique with nanoscale spatial resolution. The authors batch-fabricate the thermoelectric probe, whose junction size is about 200nm, with yield higher than 95%. The shortest time constant of the thermoelectric probe is measured to be 0.72ms. They experimentally demonstrate that the 2ω method can map out the local thermal property of a sample by monitoring the amplitude of the 2ω signal from the thermocouple junction of a probe heated by an ac. By comparing with the thermal property images obtained by other methods, they also show that the 2ω method using the point-heating and point-sensing scheme is the most suitable for the nanoscale thermal property imaging.
Patchwork field emission properties of lanthanum monosulfide thin films
Authors: Semet V. , Cahay M. , Binh Vu Thien , Fairchild S. , Wu X. , Lockwood D. J.
Published: October 2006

The field emission properties of lanthanum monosulfide (LaS) films, deposited on Si substrates by pulsed laser deposition, have been thoroughly analyzed via the scanning anode field emission microscopy technique. Using the conventional Fowler-Nordheim relation, the work function of LaS thin films has been extracted from the slope of the plot ln(J∕F2) vs 1∕F, where J is the field emission current density and F is the local applied electric field. The threshold for an emission current density of 1mA∕cm2 occurs around a 230V∕μm electric field applied across the vacuum gap. This leads to an outstanding, reproducible effective work function value of ∼1eV across a 1cm2 sample area.
Neuronal Computations with Stochastic Network States
Authors: Destexhe Alain , Contreras Diego
Published: October 2006

Neuronal networks in vivo are characterized by considerable spontaneous activity, which is highly complex and intrinsically generated by a combination of single-cell electrophysiological properties and recurrent circuits. As seen, for example, during waking compared with being asleep or under anesthesia, neuronal responsiveness differs, concomitant with the pattern of spontaneous brain activity. This pattern, which defines the state of the network, has a dramatic influence on how local networks are engaged by inputs and, therefore, on how information is represented. We review here experimental and theoretical evidence of the decisive role played by stochastic network states in sensory responsiveness with emphasis on activated states such as waking. From single cells to networks, experiments and computational models have addressed the relation between neuronal responsiveness and the complex spatiotemporal patterns of network activity. The understanding of the relation between network state dynamics and information representation is a major challenge that will require developing, in conjunction, specific experimental paradigms and theoretical frameworks.
Generation of Simian-Tropic HIV-1 by Restriction Factor Evasion
Authors: Hatziioannou Theodora , Princiotta Michael , Piatak Michael , Yuan Fang , Zhang Fengwen , Lifson Jeffrey D. , Bieniasz Paul D.
Published: October 2006

Because HIV-1 does not infect most nonhuman primates, animal modeling of human HIV infection and AIDS has primarily consisted of experimentally infecting macaques with related simian immunodeficiency viruses (SIVMAC). However, the usefulness of such models is limited by the substantial divergence between SIVMAC and HIV-1. We derived an HIV-1‐based virus that includes only small portions of SIVMAC yet replicates robustly in both transformed and primary rhesus macaque T cells. Derivation of simian-tropic HIV-1 (stHIV-1) has important implications for understanding primate lentivirus zoonosis and should allow the development of improved animal models for studies of AIDS and the evaluation of vaccines and treatments.
Astrophysical Opacity
Authors: Rogers Forrest J. , Iglesias Carlos A.
Published: October 2006

An array of problems in astronomy, cosmology, and particle physics is dependent on our understanding of the evolution and structure of stars. Stellar structure and evolution, in turn, depend on how the nuclear energy generated in the stellar center is transported to the surface. Energy transport by photons is a primary transfer mechanism. Recent improvements in the calculation of the radiative properties of stellar matter have helped resolve several long-standing discrepancies between observations and the predictions of theoretical models.