bluuebunny/crossref_metadata_2025 huggingface dataset:
Exploring DNA Structure with Cn3D
Authors: Porter Sandra G. , Day Joseph , McCarty Richard E. , Shearn Allen , Shingles Richard , Fletcher Linnea , Murphy Stephanie , Pearlman Rebecca
Published: November 2007

Researchers in the field of bioinformatics have developed a number of analytical programs and databases that are increasingly important for advancing biological research. Because bioinformatics programs are used to analyze, visualize, and/or compare biological data, it is likely that the use of these programs will have a positive impact on biology education. Over the past years, we have been working to help biology instructors introduce bioinformatics activities into their curricula by providing them with instructional materials that use bioinformatics programs and databases as educational tools. In this study, we measured the impact of a set of these materials on student learning. The activities in these materials asked students to use the molecular structure visualization program Cn3D to locate, identify, or analyze diverse features in DNA structures. Both the experimental groups of college and high school students showed significant increases in learning relative to control groups. Further, learning gains by the college students were correlated with the number of activities assigned. We conclude that working with Cn3D was important for improving student understanding of DNA structure. This study is one example of how a bioinformatics program for visualization can be used to support student learning.
Biology Intensive Orientation for Students (BIOS): A Biology “Boot Camp”
Authors: Wischusen Sheri Maples , Wischusen E. William
Published: November 2007

The Biology Intensive Orientation for Students (BIOS) Program was designed to assess the impact of a 5-d intensive prefreshman program on success and retention of biological science majors at Louisiana State University. The 2005 pilot program combined content lectures and examinations for BIOL 1201, Introductory Biology for Science Majors, as well as learning styles assessments and informational sessions to provide the students with a preview of the requirements of biology and the pace of college. Students were tracked after their BIOS participation, and their progress was compared with a control group composed of students on the BIOS waiting list and a group of BIOL 1201 students who were identified as the academic matches to the BIOS participants (high school GPA, ACT score, and gender). The BIOS participants performed significantly better on the first and second exams, they had a higher course average, and they had a higher final grade than the control group. These students also had higher success rates (grade of “A,” “B,” or “C”) during both the fall and spring semesters and remained on track through the first semester of their sophomore year to graduate in 4 yr at a significantly higher rate than the control group.
Characterization of Human Genetics Courses for Nonbiology Majors in U.S. Colleges and Universities
Authors: Bowling Bethany Vice , Huether Carl A. , Wagner Jennifer A.
Published: November 2007

We characterized college human genetics courses for nonscience majors (NSM) by 1) determining the number of U.S. institutions offering courses and the number of students taking them; and 2) surveying course instructors on course demographics, content, materials, and pedagogies. Between 2002 and 2004, an estimated 480 institutions of higher education (15.2%) offered a course: 8.4% of 1667 associate colleges, 16.1% of baccalaureate institutions, 25.3% of master's institutions, and 32.9% of doctoral institutions. This indicates a need to increase access to genetics education in 2-yr colleges. Based on instructor responses, approximately 32,000–37,000 students annually complete an NSM human genetics course out of approximately 1.9 million students earning a college degree each year (2.0%). Regarding course content, instructors consistently rated many concepts significantly higher in importance than the emphasis placed on those concepts in their courses. Although time could be a factor, instructors need guidance in the integration of the various concepts into their courses. Considering only 30.2% of the instructors were reportedly trained in genetics (another 25.4% in molecular and cellular biology) and the small fraction of students completing NSM human genetics courses, these results demonstrate the need for increasing the availability of these courses in undergraduate institutions of higher education, and particularly at 2-yr colleges.
Increased Learning Observed in Redesigned Introductory Biology Course that Employed Web-enhanced, Interactive Pedagogy
Authors: McDaniel Carl N. , Lister Bradford C. , Hanna Michael H. , Roy Harry
Published: November 2007

Our Introduction to Biology course (BIOL 1010) changed in 2004 from a standard instructor-centered, lecture-homework-exam format to a student-centered format that used Web-enhanced, interactive pedagogy. To measure and compare conceptual learning gains in the traditional course in fall 2003 with a section of the interactive course in fall 2004, we created concept inventories for both evolution and ecology. Both classes were taught by the same instructor who had taught BIOL 1010 since 1976, and each had a similar student composition with comparable biological knowledge. A significant increase in learning gain was observed with the Web-enhanced, interactive pedagogy in evolution (traditional, 0.10; interactive, 0.19; p = 0.024) and ecology (traditional, −0.05; interactive, 0.14; p = 0.000009) when assessment was made unannounced and for no credit in the last week of classes. These results strengthen the case for augmenting or replacing instructor-centered teaching with Web-enhanced, interactive, student-centered teaching. When assessment was made using the final exam in the interactive course, for credit and after studying, significantly greater learning gains were made in evolution (95%, 0.37, p = 0.0001) and ecology (143%, 0.34, p = 0.000003) when compared with learning gains measured without credit or study in the last week of classes.
National Trends in Emergency Department Antibiotic Prescribing for Children with Acute Otitis Media, 1996–2005
Authors: Fischer Thomas , Singer Adam J. , Lee Christopher , Thode Henry C.
Published: November 2007

Objectives Withholding antibiotics in nontoxic children with acute otitis media (AOM) is now recommended to reduce bacterial resistance rates. Using the National Hospital Ambulatory Medical Care Survey (NHAMCS), the authors describe the national trends for prescribing antibiotics in children with AOM presenting to emergency departments (EDs) in the United States over the past decade. The authors hypothesized that the rates of prescribing antibiotics would decline over time.

Methods This was a retrospective study of NHAMCS databases. A national sampling of ED visits for 1996–2005 was used to identify trends in ED prescription of antibiotics to patients with AOM. The National Drug Code Directory Drug Classes were used to identify type of antibiotic prescribed. Frequency and type of antibiotic prescription patterns over time were evaluated.

Results There were 2.6 million and 2.1 million ED visits for AOM during the first and last years of the study. Children ages 2–12 years accounted for about 40% of all ED visits for AOM, with another 40% in the younger than 2 years age group and 20% in the older than 12 years of age group. During the first and last year of the study, 79.2% and 91.3% of the patients with AOM were prescribed antibiotics, respectively. There was a slight increasing trend in the proportion prescribed antibiotics over time (p = 0.02). The rates of use of antibiotics for AOM were similar in all three age groups.

Conclusions There was a slight increase in the percentage of children with AOM who were prescribed antibiotics in the ED between 1996 and 2005. There was also no change in the patterns of prescribing antibiotics.
Curcumin Reduces Burn Progression in Rats
Authors: Singer Adam J. , McClain Steve A. , Romanov Alexander , Rooney Jean , Zimmerman Tom
Published: November 2007

Objectives Cutaneous burns are dynamic injuries with a central zone of necrosis surrounded by a zone of ischemia. Conversion of this ischemic zone to full necrosis over the days following injury is due in part to highly reactive oxygen radicals. Curcumin is a component of the Oriental spice turmeric that has been shown to have antioxidant and antiapoptotic properties. The authors hypothesized that treatment of burns with curcumin would reduce the conversion of the ischemic zone to full necrosis.

Methods This was a randomized controlled experiment. Twenty Sprague‐Dawley rats were used. Two burns were created on each animal's dorsum using a brass comb with four rectangular prongs preheated in boiling water and applied for 30 seconds, resulting in four rectangular 10 × 20–mm full‐thickness burns separated by three 5 × 20–mm unburned interspaces (zone of ischemia). Animals were randomized to curcumin or vehicle by oral gavage 30 minutes before injury and at 24, 48, and 72 hours after injury. Wounds were observed at one, two, and three days after injury for visual evidence of necrosis in the unburned interspaces. Full‐thickness biopsy specimens from the interspaces were evaluated with hematoxylin and eosin staining seven days after injury for evidence of necrosis. The percentage of interspaces that progressed to necrosis was compared with chi‐square tests.

Results Forty comb burns with 120 unburned interspaces were created, evenly distributed between curcumin and vehicle alone. The percentage of interspaces that progressed to full‐thickness necrosis at one, two, three, and seven days after injury in the curcumin and vehicle groups were 30% versus 63% (p = 0.003), 30% versus 70% (p < 0.001), 63% versus 95% (p = 0.02), and 63% versus 95% (p = 0.02), respectively.

Conclusions Pretreatment of rats with oral curcumin followed by once‐daily oral treatment for three days reduced the percentage of unburned skin interspaces that progressed to full necrosis.
The National Emergency Department Safety Study: Study Rationale and Design
Authors: Sullivan Ashley F. , Camargo Carlos A. , Cleary Paul D. , Gordon James A. , Guadagnoli Edward , Kaushal Rainu , Magid David J. , Rao Sowmya R. , Blumenthal David
Published: November 2007

The significance of medical errors is widely appreciated. Given the frequency and significance of errors in medicine, it is important to learn how to reduce their frequency; however, the identification of factors that increase the likelihood of errors poses a considerable challenge. The National Emergency Department Safety Study (NEDSS) sought to characterize organizational‐ and clinician‐associated factors related to the likelihood of errors occurring in emergency departments (EDs). NEDSS was a large multicenter study coordinated by the Emergency Medicine Network (EMNet; www.emnet‐usa.org). It was designed to determine if reports by ED personnel about safety processes are significantly correlated with the actual occurrence of errors in EDs. If so, staff reports can be used to accurately identify processes for safety improvements. Staff perceptions were assessed with a survey, while errors were assessed through chart review of three conditions: acute myocardial infarction, acute asthma, and reductions of dislocations under procedural sedation. NEDSS also examined the characteristics of EDs associated with the occurrence of errors. NEDSS is the first comprehensive national study of the frequency and types of medical errors in EDs. This article describes the methods used to develop and implement the study.
The Generality/Specificity of Expertise in Scientific Reasoning
Authors: Schunn Christian D. , Anderson John R.
Published: November 2007

Previous research on scientific reasoning has shown that it involves a diverse set of skills. Yet, little is known about generality or domain specificity of those skills, an important issue in theories of expertise and in attempts to automate scientific reasoning skills. We present a study designed to test what kinds of skills psychologists actually use in designing and interpreting experiments and contrast expertise within a particular research area with general expertise at designing and interpreting experiments. The results suggest that psychologists use many domain‐general skills in their experimentation and that bright and motivated Carnegie Mellon undergraduates are missing many of these skills. We believe that these results have important implications for psychological and artificial intelligence models of expertise, as well as educational implications in the domain of science instruction.
An Attractor Model of Lexical Conceptual Processing: Simulating Semantic Priming
Authors: Cree George S. , McRae Ken , McNorgan Chris
Published: November 2007

An attractor network was trained to compute from word form to semantic representations that were based on subject‐generated features. The model was driven largely by higher‐order semantic structure. The network simulated two recent experiments that employed items included in its training set (McRae and Boisvert, 1998). In Simulation 1, short stimulus onset asynchrony priming was demonstrated for semantically similar items. Simulation 2 reproduced subtle effects obtained by varying degree of similarity. Two predictions from the model were then tested on human subjects. In Simulation 3 and Experiment 1, the items from Simulation 1 were reversed, and both the network and subjects showed minimally different priming effects in the two directions. In Experiment 2, consistent with attractor networks but contrary to a key aspect of hierarchical spreading activation accounts priming was determined by featural similarity rather than shared superordinate category. It is concluded that semantic‐similarity priming is due to featural overlap that is a natural consequence of distributed representations of word meaning.
Basic Strategy for Acetate Film Preservation
Authors: Reilly James M.
Published: November 2007

This article provides an overview of environmental specifications for film storage. It explains the relationship between temperature, relative humidity (RH), and ‘vinegar syndrome,’ the slow chemical decomposition of acetate plastics leading to loss of their value in a film collection. Its main purpose is to help collection managers evaluate the quality of the storage environment they provide for their film.
Digitization as a Preservation Method – A Comment from Singapore
Authors: Wah Pitt Kuan
Published: November 2007

While the main body of the ARL Report contains largely high level statements, I would also expect such a Report to highlight more than the pros and cons of various information carriers or media, and to go beyond “recognizing digitization as a preservation reformatting method.”
Unde Malum? Zu einer kritischen Revision von Hans Blumenbergs Legitimität der Neuzeit
Authors: Schmidt Christoph
Published: November 2007

I Die vermeintliche „Überwindung“ der politischen Theologie

Die Geschichte der politischen Theologie in der Moderne erweist sich vorläufig immer noch als die Geschichte ihrer misslungenen Überwindungen. Trotz ihrer vielfachen Erledigungen zeigt die politische Theologie, entgegen Hans Blumenbergs Prognose, eine erstaunliche Fähigkeit zur „Selbstbehauptung“. Ihre Resistenz verdankt sie dabei nicht zum Geringsten der Prätention all derjenigen Gegner, die meinten, man könne, indem man eine spezifische Form von politischer Theologie kritisiert, gleich mit allen Spielarten des politisch-theologischen Diskurses aufräumen. Ohnehin werden die meisten Überwindungen der politischen Theologie im Namen einer anderen politischen Theologie vorgenommen. So die berühmteste, von Erik Peterson stammende Widerlegung, die als Fazit der Untersuchung zum „Monotheismus als politisches Problem“ gegen Carl Schmitts politische Theologie gewendet war und den eher anstößigen Sprachgebrauch von der „Erledigung“ in Umlauf gebracht hat. Sie wurde von Peterson jedenfalls im Namen der trinitarischen Theologie des Augustinus vorgenommen, wobei Peterson eine solche Erledigung schon im Rahmen einer an Paulus' Römerbrief orientierten Theopolitik erprobt hatte. Darüber hinaus muss der Begriff der politischen Theologie nicht notwendig gegen die „Legitimität der Moderne“ eingesetzt sein, sondern versteht sich oft genug als deren dialektische Kritik, wie etwa bei Martin Buber, Paul Tillich oder später bei Jürgen Moltmann und Johann Baptist Metz.
Spatial Organization of Neuronal Population Responses in Layer 2/3 of Rat Barrel Cortex
Authors: Kerr Jason N. D. , de Kock Christiaan P. J. , Greenberg David S. , Bruno Randy M. , Sakmann Bert , Helmchen Fritjof
Published: November 2007

Individual pyramidal neurons of neocortex show sparse and variable responses to sensory stimuliin vivo. It has remained unclear how this variability extends to population responses on a trial-to-trial basis. Here, we characterized single-neuron and population responses to whisker stimulation in layer 2/3 (L2/3) of identified columns in rat barrel cortex usingin vivotwo-photon calcium imaging. Optical detection of single action potentials from evoked calcium transients revealed low spontaneous firing rates (0.25 Hz), variable response probabilities (range, 0–0.5; mean, 0.2 inside barrel column), and weak angular tuning of L2/3 neurons. On average, both the single-neuron response probability and the percentage of the local population activated were higher in the barrel column than above septa or in neighboring columns. Within the barrel column, mean response probability was highest in the center (0.4) and declined toward the barrel border. Neuronal pairs showed correlations in both spontaneous and sensory-evoked activity that depended on the location of the neurons. Correlation decreased with increasing distance between neurons and, for neuronal pairs the same distance apart, with distance of the pair from the barrel column center. Although neurons are therefore not activated independently from each other, we did not observe precisely repeating spatial activation patterns. Instead, population responses showed large trial-to-trial variability. Nevertheless, the accuracy of decoding stimulus onset times from local population activity increased with population size and depended on anatomical location. We conclude that, despite their sparseness and variability, L2/3 population responses show a clear spatial organization on the columnar scale.
Activity-Dependent Ubiquitination of GABAAReceptors Regulates Their Accumulation at Synaptic Sites
Authors: Saliba Richard S. , Michels Guido , Jacob Tija C. , Pangalos Menelas N. , Moss Stephen J.
Published: November 2007

GABAAreceptors (GABAARs) are the major mediators of fast synaptic inhibition in the brain. In neurons, these receptors undergo significant rates of endocytosis and exocytosis, processes that regulate both their accumulation at synaptic sites and the efficacy of synaptic inhibition. Here we have evaluated the role that neuronal activity plays in regulating the residence time of GABAARs on the plasma membrane and their targeting to synapses. Chronic blockade of neuronal activity dramatically increases the level of the GABAAR ubiquitination, decreasing their cell surface stability via a mechanism dependent on the activity of the proteasome. Coincident with this loss of cell surface expression levels, TTX treatment reduced both the amplitude and frequency of miniature inhibitory synaptic currents. Conversely, increasing the level of neuronal activity decreases GABAAR ubiquitination enhancing their stability on the plasma membrane. Activity-dependent ubiquitination primarily acts to reduce GABAAR stability within the endoplasmic reticulum and, thereby, their insertion into the plasma membrane and subsequent accumulation at synaptic sites. Thus, activity-dependent ubiquitination of GABAARs and their subsequent proteasomal degradation may represent a potent mechanism to regulate the efficacy of synaptic inhibition and may also contribute to homeostatic synaptic plasticity.
Characterization of the Role of Microtubule-Associated Protein 1B in Metabotropic Glutamate Receptor-Mediated Endocytosis of AMPA Receptors in Hippocampus
Authors: Davidkova Genoveva , Carroll Reed C.
Published: November 2007

The mGluR-dependent endocytosis of AMPA receptors (AMPARs) in the CA1 region is protein synthesis dependent. However, why this form of trafficking, and not that mediated by NMDA receptor activation, is dependent on protein translation is unclear. Here we have studied the contribution of the cytoskeletal microtubule-associated protein 1B (MAP1B) to the pathway-specific internalization of AMPARs. Treatments of cultured neurons with 3,4-dihydroxyphenylglycol (DHPG) or NMDA, both of which drive AMPAR endocytosis, caused a translation-dependent increase in the dendritic levels of MAP1B protein. Although interfering with protein synthesis using short interfering RNA (siRNA) to eEF2 kinase (eukaryotic elongation factor 2 kinase) blocked the dendritic MAP1B increase by both pathways, it selectively blocked the DHPG- and not the NMDA-induced AMPAR endocytosis. In support of MAP1B synthesis contributing to metabotropic glutamate receptor (mGluR)-mediated AMPAR endocytosis, siRNA against MAP1B in CA1 cultured neurons specifically blocked the DHPG-induced AMPAR internalization. Previous studies suggest a direct interaction between MAP1B and the AMPAR-binding protein GRIP1. Biochemical studies establish that MAP1B associates with GRIP1 and forms a complex with GluR2in vivoin rat hippocampus. Furthermore, the interaction between MAP1B and GRIP1 increased significantly in acute slices after treatment with DHPG and not NMDA. Together, these findings suggest that MAP1B plays a selective role in the DHPG-induced endocytosis of AMPARs, perhaps through its interaction with GRIP1.
Glial Cell Migration in the Eye Disc
Authors: Silies Marion , Yuva Yeliz , Engelen Daniel , Aho Annukka , Stork Tobias , Klämbt Christian
Published: November 2007

Any complex nervous system is made out of two major cell types, neurons and glial cells. A hallmark of glial cells is their pronounced ability to migrate. En route to their final destinations, glial cells are generally guided by neuronal signals. Here we show that in the developing visual system ofDrosophilaglial cell migration is largely controlled by glial–glial interactions and occurs independently of axonal contact. Differentiation into wrapping glia is initiated close to the morphogenetic furrow. Using single cell labeling experiments we identified six distinct glial cell types in the eye disc. The migratory glial population is separated from the wrapping glial cells by the so-called carpet cells, extraordinary large glial cells, each covering a surface area of ∼10,000 epithelial cells. Subsequent cell ablation experiments demonstrate that the carpet glia regulates glial migration in the eye disc epithelium and suggest a new model underlying glial migration and differentiation in the developing visual system.
Sensitization of Pain-Modulating Neurons in the Rostral Ventromedial Medulla after Peripheral Nerve Injury
Authors: Carlson Jonathan D. , Maire Jennifer J. , Martenson Melissa E. , Heinricher Mary M.
Published: November 2007

Nerve injury can lead to mechanical hypersensitivity in both humans and animal models, such that innocuous touch produces pain. Recent functional studies have demonstrated a critical role for descending pain-facilitating influences from the rostral ventromedial medulla (RVM) in neuropathic pain, but the underlying mechanisms and properties of the relevant neurons within the RVM are essentially unknown. We therefore characterized mechanical responsiveness of physiologically characterized neurons in the RVM after spinal nerve ligation, a model of neuropathic pain that produces robust mechanical hyperalgesia and allodynia. RVM neurons were studied 7–14 d after spinal nerve ligation, and classified as “on-cells,” “off-cells,” or “neutral cells” using standard criteria of changes in firing associated with heat-evoked reflexes. On-cells are known to promote nociception, and off-cells to suppress nociception, whereas the role of neutral cells in pain modulation remains an open question. Neuronal and behavioral responses to innocuous and noxious mechanical stimulation were tested using calibrated von Frey filaments (4–100 g) applied to the hindpaws ipsilateral and contralateral to the injury, and in sham-operated and unoperated control animals. On- and off-cells recorded in nerve-injured animals exhibited novel responses to innocuous mechanical stimulation, and enhanced responses to noxious mechanical stimulation. Neuronal hypersensitivity in the RVM was correlated with behavioral hypersensitivity. Neutral cells remained unresponsive to cutaneous stimulation after nerve injury. These data demonstrate that both on- and off-cells in the RVM are sensitized to innocuous and noxious mechanical stimuli after nerve injury. This sensitization likely contributes to allodynia and hyperalgesia of neuropathic pain states.
The Down Syndrome Critical Region Protein RCAN1 Regulates Long-Term Potentiation and Memory via Inhibition of Phosphatase Signaling
Authors: Hoeffer Charles A. , Dey Asim , Sachan Nita , Wong Helen , Patterson Richard J. , Shelton John M. , Richardson James A. , Klann Eric , Rothermel Beverly A.
Published: November 2007

Regulator of calcineurin 1 (RCAN1/MCIP1/DSCR1) regulates the calmodulin-dependent phosphatase calcineurin. Because it is located on human chromosome 21,RCAN1has been postulated to contribute to mental retardation in Down syndrome and has been reported to be associated with neuronal degeneration in Alzheimer's disease. The studies herein are the first to assess the role ofRCAN1in memory and synaptic plasticity by examining the behavioral and electrophysiological properties ofRCAN1knock-out mice. These mice exhibit deficits in spatial learning and memory, reduced associative cued memory, and impaired late-phase long-term potentiation (L-LTP), phenotypes similar to those of transgenic mice with increased calcineurin activity. Consistent with this, theRCAN1knock-out mice display increased enzymatic calcineurin activity, increased abundance of a cleaved calcineurin fragment, and decreased phosphorylation of the calcineurin substrate dopamine and cAMP-regulated phosphoprotein-32. We propose a model in whichRCAN1plays a positive role in L-LTP and memory by constraining phosphatase signaling.
Polarity-Regulating Kinase Partitioning-Defective 1/Microtubule Affinity-Regulating Kinase 2 Negatively Regulates Development of Dendrites on Hippocampal Neurons
Authors: Terabayashi Takeshi , Itoh Tomohiko J. , Yamaguchi Hideki , Yoshimura Yuta , Funato Yosuke , Ohno Shigeo , Miki Hiroaki
Published: November 2007

Neurons are highly polarized cells that possess two morphologically and functionally different types of protrusions, axons and dendrites, that function in the transmission and reception of neural signals, respectively. A great deal of attention has been paid to the specification and guidance of axons, but the mechanism of dendrite development remains mostly unknown. We report here that a polarity-regulating kinase, partitioning-defective 1 (Par1b)/microtubule affinity-regulating kinase 2 (MARK2), specifically regulates development of dendrites in hippocampal neurons. Ectopic expression of Par1b/MARK2 shortens the length and decreases branching of dendrites without significant effects on axons. Knockdown of endogenous Par1b/MARK2 by RNA interference stimulates dendrite development. Wnt stimulation and Dishevelled expression, both of which are known to induce dendrite development, induced recruitment of Par1b/MARK2 to the membrane fraction. Expression of a Par1b/MARK2 mutant, that contains a myristoylation signal and accumulates exclusively in membranes, does not affect dendrite development. In addition, Par1b/MARK2 efficiently phosphorylated MAP2, which is localized mainly in dendrites. These results indicate that Par1b/MARK2 negatively regulates dendrite development through phosphorylation of MAP2.
Analyse der Zustandserreichbarkeit zur Fehlergrenzwertbestimmung in Hochauftriebssystemen (Reachability Analysis for the Determination of Monitoring Thresholds in Highlift Systems)
Authors: Geilsdorf Hendrik , Raksch Christian , Carl Udo
Published: November 2007

Dieser Beitrag gibt zunächst einen Überblick über wichtige Methoden der Erreichbarkeitsanalyse. Anhand diverser Kriterien wie Komplexität, Rechenzeit und Anwendbarkeit wird ein Verfahren ausgewählt und zur Bestimmung von Fehlergrenzwerten für die Überwachung eines elektrischen Landeklappenantriebssystemes angewendet. Mit Hilfe der nichtlinearen Simulation eines Fehlerfalles wird diese Methode abschließend validiert.
Nonlinear System Identification in Stroke Rehabilitation (Nichtlineare Systemidentifikation in der Schlaganfallrehabilitation)
Authors: Bernhardt Michael , Angerer Bernhard , Buss Martin , Struppler Albrecht
Published: November 2007

The repetitive peripheral magnetic stimulation (RPMS) is an innovative approach in treatment of central paresis, e.g. after stroke. In this article we present a neuromuscular model for the RPMS-induced muscle contraction. This model is the basis for our two recent goals in research: Position controlled movement induction and automated therapy evaluation by means of system identification. In order to adapt the model parameters to the individual, a nonlinear on-line system identification method is proposed.
Hydroxyapatite-alginate composite for lead removal in artificial gastric fluid
Authors: Mavropoulos Elena , Rocha-Leão Maria Helena , da Rocha Nilce C.C. , Prado da Silva Marcelo H. , Rossi Alexandre Malta
Published: November 2007

Millimetric spherical beads of a biocompatible composite were produced from sodium alginate, a natural polysaccharide, and nanostructured hydroxyapatite (HA). It was shown that the composite was effective in the removal of lead ions and lead phosphate nanoparticles from high-contaminated simulated gastric fluid. X-ray diffraction spectroscopy and scanning electron microscopy analyses performed on HA–alginate beads after the Pb2+uptake showed that nanocrystals of a lead phosphate, [Pb10–xCax(PO4)6Cl2], were precipitated on the bead surface. The cross-linked polymer chain had a double role: (i) keep Pb2+ions and lead phosphate nanoparticles bounded to the bead surface, preventing their bioavailability in stomach fluid; and (ii) delay HA dissolution in the acidic conditions of the stomach, assuring that an excess of Ca2+will not be released to simulated gastric fluid. Desorption experiments in simulated enteric fluid revealed that lead remained immobilized in the calcium phosphate phase in the intestinal tract. These results indicate HA–alginate composite as a potential system for heavy metals removal from contaminated gastric and enteric human fluids, minimizing its adsorption by the human body.
Improvement of plasticity by tailoring combination of constituent elements in Ti-rich Ti–Zr–Be–Cu–Ni bulk metallic glasses
Authors: Park E.S. , Chang H.J. , Lee J.Y. , Kim D.H.
Published: November 2007

The effect of replacement of Ti with Y or Nb in Ti-rich Ti–Zr–Be–Cu–Ni bulk metallic glasses (BMGs) has been investigated. The minor addition (MA) of Y (Y–Ti: +58 kJ/mol) induced phase separation into Y-rich crystalline particles and Ti-rich amorphous matrix, while the MA of Nb (Nb–Ti: +10 kJ/mol) led to nanocrystallization in Ti-rich BMGs with icosahedral nuclei. This result indicates that MA of elements having positive enthalpy of mixing can induce a different degree of instability in the single amorphous matrix depending on the amount of repulsive interaction energy. In particular, MA of Nb (up to 4 at.%) significantly increased the compressive fracture strain (ϵf) up to ∼9.35 ± 0.2%, which indicates that the plasticity of BMGs can be enhanced by the size-modulated icosahedral phase embedded in the amorphous matrix.
Poly(methyl methacrylate)–nanoribbon nanocomposites with high thermal stability and improvement in the glass-transition temperature
Authors: Ding Yanyan , Gui Zhou , Zhu Jixin , Wang Zhengzhou , Hu Yuan , Song Lei
Published: November 2007

A novel poly(methyl methacrylate) (PMMA) nanocomposite containing dispersed inorganic nanoribbons [ZnO–0.15Zn(CH3COO)2–0.85H2O] was prepared by free radical polymerization of methyl methacrylate in the acetone solution. Experimental results showed that inorganic nanoribbons were uniformly distributed in and bonded to the PMMA host matrix without macroscopic organic–inorganic phase separation. It was found that the thermal stability and glass-transition temperature of the nanocomposite films increased effectively with increasing inorganic content at low content and remained above 1 wt% inorganic content. These results suggest the network formation because of the strong interaction between the inorganic nanoribbons and the polymer matrix, which induces the mobility restriction of polymer chains. The characteristics of the one-dimensional inorganic nanoribbons we used here may play a key role in the formation of the “cross-link” networks and in the decision to lower the content of the inorganic nanoribbon additive.
Sedimentation of Cu-rich intermetallics in liquid lead-free solders
Authors: Song Jenn-Ming , Shen Yu-Lin , Chuang Hsin-Yi
Published: November 2007

This study investigated the behavior of Cu-containing intermetallic compounds (IMCs) in liquid Sn–Ag and Sn–Zn solders. Experimental results show that for the intermetallics investigated, Cu–Sn and Cu–Zn compounds, the occurrence of settling was dominated by the crystalline temperature of IMCs, buoyancy due to difference in densities, and dissolution potential for the compounds into the liquid. The complete dissolution of Cu–Zn compounds, which took place in the Sn–Zn solders when the Cu content exceeded a critical value, might be ascribed to the depletion of Zn in the melt.
Effects of processing variables on microstructure formation in AZ31 magnesium alloys solidified with an electromagnetic vibration technique
Authors: Li Mingjun , Tamura Takuya , Miwa Kenji
Published: November 2007

In the present study, we solidified magnesium-based AZ31 alloys by an electromagnetic vibration technique in a superconducting magnetic field at a vibration frequency of 500 Hz. Two groups of processing variables were used to carry out experiments; one is that the electric current is set as 60 A so as to testify to the influence of magnetic flux density on microstructure development from 1 up to 10 T. The other is that the electric current increases from 10 up to 120 A in the static magnetic field of 10 T, from which the dependence of structure formation on electric current is revealed. It is found that with the increase of both magnetic flux density and the level of electric current, solidified structures experience a transition from coarse dendrites to equiaxed grains. The melt fluid induced by the vibration force during solidification may promote the dendrite to a fragment. Meanwhile, the solids can be driven to move out of the operating region of the solute redistribution boundary. These effects make it difficult to form a complete dendrite but a refined structure. Furthermore, the vibration force can result in the formation of deformation twins in the alloy that has a low critical stress for basal slip. Regarding the effect of the electric current on microstructure, heat (measured in joules) can be produced when a large electric current is imposed, which can ripen the microstructure and induce a nonuniform structure. The slow cooling rate also makes the number fraction of deformation twinning decrease due to a rapid migration rate of atoms at high temperatures.
Solid-state nuclear magnetic resonance characterization of PE–PEG/silica hybrid materials prepared by microwave-assisted sol-gel process
Authors: Geppi Marco , Mollica Giulia , Borsacchi Silvia , Marini Michele , Toselli Maurizio , Pilati Francesco
Published: November 2007

Organic–inorganic hybrid materials were prepared by sol-gel processes starting from tetraethoxysilane (TEOS) and a triethoxysilane-terminated polyethylene–b-poly(ethylene glycol) copolymer (PE–PEG–Si). Curing of the initial reactant solution was carried out under different reaction conditions, and the materials so obtained were investigated by solid-state nuclear magnetic resonance (NMR). In particular, the molecular structure resulting from a conventional oven heating was compared with that obtained by unconventional microwave heating. The results highlighted that the extent of condensation reactions occurring over several hours under conventional heating is very similar to that resulting in 1 min under microwave heating. Additionally, 29Si–magic angle spinning (MAS) spectra showed that even though the overall extent of cross-linking in the inorganic network is only slightly affected by the thermal history of the sample, significantly different distributions of silicon sites can be present. 13C–CP/MAS selective spectra revealed the presence of PE “crystalline” domains within the organic phase, not detectable by differential scanning calorimetry (DSC). Finally, 1H–MAS spectra showed that different hydrogen-bond interactions are present in samples obtained under different curing conditions.
Pyroelectricity versus conductivity in soft lead zirconate titanate (PZT) ceramics
Authors: Kamel Talal M. , de With G.
Published: November 2007

The electrical behavior of modified soft lead zirconate titanate (PZT) ceramics has been studied as a function of temperature at different direct current (dc) electric fields and grain sizes. As ferroelectrics, such as PZT, are highly polarizable materials, poling, depolarization, and electric conduction contribute to the total electrical current, which leads to anomalous electrical behavior as a function of temperature. The PZT appeared to have a high pyroelectric coefficient, and it was found that the displacement current hides the conduction current near room temperature. The (long-time) steady-state electrical resistivity of the soft PZT used has a typical, relatively high value of 3.6 × 1012Ω·cm near room temperature. The resistivity above the Curie temperature was two orders of magnitude lower than the room temperature. The resistivity decreases with increasing grain size probably due to the increased Pb vacancy concentration resulting as a consequence of a higher sintering temperature. The values of activation energies suggest that the charge carriers at high temperature are mainly oxygen vacancies. At intermediate temperature, the electrical behavior is controlled by the counteracting effect of depolarization and conduction. Considering the pyroelectric effect and the conduction, it was thus possible to explain the electrical behavior of this soft PZT ceramic over the temperature range considered.
Cathodoluminescence study of defects created by Vickers indentation in hydrothermal ZnO crystals
Authors: Mass J. , Avella M. , Jiménez J. , Callahan M. , Bliss D. , Wang Buguo
Published: November 2007

Vickers indentations of ZnO crystals grown by the hydrothermal method were studied by cathodoluminescence. The defects induced by indentation influenced the luminescence spectrum, indicating the generation of non radiative recombination centers and a band close to the first phonon replica of the free exciton, in the surrounding area near the indentation. The possible nature of the defects responsible for such band is discussed. A comparison with polishing induced damage is also presented.
Plastias de estenoses de intestino delgado na doença de Crohn: resultados imediatos e tardios
Authors: Ayrizono Maria de Lourdes Setsuko , Leal Raquel Franco , Coy Cláudio Saddy Rodrigues , Fagundes João José , Góes Juvenal Ricardo Navarro
Published: November 2007

RACIONAL: As enteroplastias constituem alternativa cirúrgica no tratamento da estenose da doença de Crohn. OBJETIVO: Analisar, retrospectivamente, a evolução precoce e tardia do tratamento cirúrgico das estenoses do intestino delgado, segmento ileocecal ou anastomose ileocólica secundária à doença de Crohn, com emprego de plastias intestinais. MÉTODOS: Foram estudados 28 doentes, operados entre setembro de 1991 e maio de 2004, com seguimento médio pós-operatório de 58,1 meses. Dezesseis (57,1%) eram do sexo masculino, com média etária de 33,3 anos, e 13 doentes (46,4%) apresentavam ressecções intestinais prévias. Foram realizadas 116 plastias, sendo 94 (81%) à Heineke-Mikulicz, 15 (13%) do tipo Finney e 7 (6%) ileocoloplastias látero-laterais. Em 18 doentes (64,3%) realizaram-se ressecções intestinais concomitantes. RESULTADOS: Verificaram-se 14 complicações em 7 doentes (25%) e um óbito (3,6%), secundário a complicações pulmonares após reoperações por sangramento intestinal da anastomose êntero-entérica. Ocorreram duas complicações gerais (14,3%), em dois doentes (7,1%) e oito complicações locais precoces (57,1%), em sete doentes (25%), sendo a mais freqüente deiscência de plastia, em três casos (10,7%). Complicações locais tardias ocorreram em dois doentes (7,1%), ambos com hérnia incisional e fístula êntero-cutânea. Recidiva sintomática da estenose ocorreu em 17 doentes (63%) e 2 deles (7,4%), apresentaram fístulas êntero-cutâneas, sendo o índice de reoperação de 40,7%. Observaram-se quatro recidivas (3,5%), em três doentes (11,1%) em local de plastia prévia, sendo mais comum no tipo Finney (20%). CONCLUSÃO: As plastias apresentaram baixos índices de complicações e propiciam alívio dos sintomas. Uma vez que muitos doentes com doença de Crohn necessitarão de várias cirurgias ao longo da vida, as plastias intestinais constituem alternativas eficazes, com resolução dos sintomas obstrutivos, evitando-se ressecções intestinais extensas e suas conseqüências.
Gender effect on the clinical measurement of swallowing
Authors: Alves Leda Maria Tavares , Cassiani Rachel de Aguiar , Santos Carla Manfredi dos , Dantas Roberto Oliveira
Published: November 2007

BACKGROUND: Swallowing coordination is affected by cortical and subcortical inputs from the central nervous system. Our hypothesis is that the swallowing dynamics may be influenced by gender. AIM: To evaluate the influence of gender on water swallowing dynamics. METHODS: We studied 111 health subjects, 36 men, aged 24-77 years (mean: 46.3 ± 16.1 years) and 75 women, aged 22-75 years (mean: 39.6 ± 13.3 years). All volunteers swallowed in triplicate 50 mL of water at 4ºC while precisely timed, when we measured the time to swallow all the volume and counted the number of swallows. We calculated the inter-swallow interval: the time to complete the task, in seconds, divided by the number of swallows; swallowing velocity: volume drunk (mL) by the time taken (s); swallowing volume capacity: volume drunk (mL) divided by the number of swallows. RESULTS: Women had a shorter inter-swallow interval, slower swallowing velocity and lower volume capacity than men. CONCLUSION: Gender has an effect on water swallowing dynamics, with women having a lower swallowing velocity and a lower volume capacity in each swallow than men.
Enxertia precoce da nogueira-macadâmia
Authors: Campo Dall'Orto Fernando Antonio , Ojima Mário , Barbosa Wilson , Sabino José Carlos , Rigitano Orlando
Published: November 2007

A carência de mudas enxertadas de nogueira-macadâmia (Macadamia integrifolia Maid. e Bet.) constitui, ainda hoje, um dos grandes entraves ao efetivo estabelecimento da cultura nas condições brasileiras. Apesar dos recentes avanços técnicos conseguidos na sua propagação, o procedimento adotado à produção de mudas ainda demanda um período de dois a três anos, para sua efetiva instalação no campo. Neste trabalho, levado a efeito na Estação Experimental do Instituto Agronômico, em Tietê, SP, demonstrou-se a exequibilidade de produção de mudas de macadâmia, em tempo bem mais abreviado, isto é, apenas doze meses. O novo processo de obtenção de mudas precoces de macadâmia, sob ripado, pela enxertia de garfos pouco lignificados e protegidos com saquinhos plásticos, utilizando cavalos novos com cerca de seis meses de idade, além de possibilitar maior facilidade operacional e eficiência no pegamento dos enxertos, poderá propiciar a instalação do nogueiral com antecipação de cerca de um ano, em relação ao sistema corrente.
Tolerância de trigo, triticale e centeio a diferentes níveis de ferro em solução nutritiva
Authors: Camargo Carlos Eduardo de Oliveira , Felício João Carlos , Freitas José Guilherme de , Ferreira Filho Antonio Wilson Penteado
Published: November 2007

Em um experimento estudou-se o comportamento diferencial de treze cultivares de trigo, seis de triticale e um de centeio e, em outro, o comportamento de vinte cultivares de trigo, empregando-se soluções nutritivas arejadas contendo cinco concentrações de ferro (0,56; 5,0; 10,0; 20,0 e 40,0 mg/litro) à temperatura de 25 ±1°C, e pH 4,0. A média do crescimento das raízes dos cultivares, durante doze dias, nas diferentes soluções de tratamento foi o parâmetro utilizado para a avaliação da tolerância. Os cultivares de trigo IAC-212 e IAC-215 (Experimento 1) e IAC-29, IAC-74, IAC-203, IAC-207 e IAC-211 (Experimento 2) foram tão tolerantes ou mais que o 'Siete Cerros', empregado como controle, constituindo-se em fontes genéticas de valor para o programa de melhoramento do Instituto Agronômico. Os cultivares de triticale PFT 7719, PFT 7882, TCEP 7889 e Juanillo 159 foram mais tolerantes do que o 'PFT 766' e o 'TCEP 77138'. 0 cultivar de centeio Branco exibiu moderada tolerância à toxicidade de ferro. Os cultivares de trigo IAC-161, IAC-162, Anahuac, IAC-213, IAC-214, IAC-217 e IAC-219 (Experimento 1) e IAC-205 e IAC-60 (Experimento 2) mostraram sensibilidade à toxicidade de ferro semelhante ao 'BH-1146', usado como controle. O cultivar de trigo IAC-74 e os de triticale PFT 7719, PFT 7882 e TCEP 7889, tolerantes à toxicidade de ferro e alumínio, constituem germoplasmas valiosos para cultivo em solos ácidos.
Omissão de macronutrientes em plantas de amendoim
Authors: Rodrigues Filho Francisco Solano de Oliveira , Feitosa Celi Teixeira , Gerin Marcelo Aparecido Nunes
Published: November 2007

Plantas de amendoim Arachis hypogaea L. 'Tatu' foram cultivadas em condições de casa de vegetação, em vasos de Mitscherlich contendo areia lavada e irrigados com solução nutritiva completa e com soluções nutritivas com a omissão de cada macronutriente (N, P, K, Ca, Mg e S). As plantas mostraram sintomas de deficiência de macronutrientes, com exceção do fósforo, na ausência de cada elemento, relacionados com os seus baixos teores e redução no crescimento, desenvolvimento e produção de matéria seca.
Eliminação de anomalias fisiológicas, in vitro, de plântulas de pessegueiro
Authors: Barbosa Wilson , Campo Dall'Orto Fernando Antonio , Ojima Mário
Published: November 2007

O experimento objetivou eliminar os sintomas de roseta e ananismo em híbridos de pessegueiro (Prunus persica L. Batsch) precoces, provenientes de cultura embrionária. Essas anomalias fisiológicas aparecem em vista dos inibidores de crescimento presentes nos meristemas apicais dos embriões. Dois processos de recuperação de vitroplântulas anômalas foram adotados: (a) eliminação da porção apical logo acima da primeira gema, a partir dos cotilédones; (b) manutenção das vitroplântulas por trinta dias em ambiente de vernalização com temperatura de 5-10 º C. Os melhores resultados foram obtidos quando se eliminou a dominância do meristema apical; as vitroplântulas mantidas em sala de crescimento emitiram, em cinco dias, brotações novas e normais e se desenvolveram rapidamente. Aquelas submetidas à quebra de endodormência, porém,retomaram parcialmente o desenvolvimento, de forma lenta e anormal.