bluuebunny/crossref_metadata_2025 huggingface dataset:
Accruals Quality, Stock Returns, and Macroeconomic Conditions
Authors: Kim Dongcheol , Qi Yaxuan
Published: May 2010

ABSTRACT: This study examines whether and how earnings quality, measured as accruals quality (AQ), affects the cost of equity capital. Using two-stage cross-sectional regression tests, we find that the AQ risk factor is significantly priced, after controlling for low-priced stocks. This result is robust in tests using individual stocks, various portfolio formations, and different beta estimations. Furthermore, we show that AQ and its pricing effect systematically vary with business cycles and macroeconomic variables. In particular, this pricing effect is prominent in total AQ and innate AQ but not in discretionary AQ. The risk premium associated with AQ exists only in economic expansion but not in recession periods. Poorer AQ firms are more vulnerable to macroeconomic shocks. The risk premium and the dispersion of AQ are also related to future economic activity. Overall, our results suggest that AQ contributes to the cost of equity capital and that its pricing effect is associated with fundamental risk.
Consensus Information and Nonprofessional Investors’ Reaction to the Revelation of Estimate Inaccuracies
Authors: Koonce Lisa , Williamson Michael G. , Winchel Jennifer
Published: May 2010

ABSTRACT: To curb opportunism in financial reporting, researchers and regulators have proposed that firms be required to report reconciliations of prior year estimates. We provide experimental evidence that such disclosures are not sufficient for nonprofessional investors to identify firms that are opportunistic in their estimates. We also offer evidence suggesting that the value of these disclosures can be enhanced when nonprofessional investors seek out information about the estimate accuracy of other firms in the industry (i.e., consensus information). Our study provides insights about these disclosures and the mechanisms that enhance their effectiveness. Our findings have broad implications for standard-setters and future research designed to assist in identifying opportunistic management behavior.
Diabetes-Specific Family Conflict and Blood Glucose Monitoring in Adolescents With Type 1 Diabetes: Mediational Role of Diabetes Self-Efficacy
Authors: Sander Emily P. , Odell Shannon , Hood Korey K.
Published: May 2010

Purpose. To determine whether the association between diabetes-specific family conflict and self-monitoring of blood glucose (SMBG) frequency is mediated by diabetes self-efficacy.

Methods. A total of 276 adolescents with type 1 diabetes (aged 15.6 ± 1.4 years; duration of diabetes 6.6 ± 1.8 years; A1C 8.9 ± 1.8%) completed measures of diabetes-specific family conflict and self-efficacy. Sociodemographic, family, and disease characteristics (including SMBG frequency and glycemic control) were obtained at the clinic visit.

Results. Multivariate analyses were used to test the mediational role of self-efficacy. The first model established that family conflict was associated with lower levels of self-efficacy. The second model established that increased family conflict was associated with lower SMBG frequency. In the third model, self-efficacy was added, and the effect of family conflict on SMBG frequency became less significant (P = 0.001 to P = 0.03). The indirect effect of family conflict on SMBG frequency through diabetes self-efficacy was significant (Sobel = 2.10, P = 0.035) and explained 22% of the association between family conflict and SMBG frequency.

Conclusions. Results confirm a partial mediational role of diabetes self-efficacy and suggest that a family environment characterized by conflict may also contain poorer self-efficacy in the adolescent. In these cross-sectional analyses, both variables contributed to less frequent SMBG. Future longitudinal research to confirm these relationships and potential avenues for intervention are discussed.
Phenomenology of the nucleon-nucleon potential
Authors: Kamuntavičius Gintautas , Kaminskas Marius
Published: May 2010

A local nucleon-nucleon potential expansion is developed in terms of orthogonal projectors. Considering the nucleon-nucleon (NN) potential as a completely phenomenological structure, the expansion provides an opportunity to obtain the NN scattering phase shifts that can be described by applying a restricted set of operators, dependent on angular and spin-isospin degrees of freedom of the interacting nucleons. The results obtained with an approximation for eight basic operators (central, spin-orbit and tensorial) are consistent with experience in the field, and provide directions for further modifications of realistic NN potentials.
Inhibition of calpain but not caspase activity by spectrin fragments
Authors: Rolius Ramunas , Antoniou Chloe , Nazarova Lidia , Kim Stephen , Cobb Garrett , Gala Pooja , Rajaram Priyanka , Li Qufei , Fung Leslie
Published: May 2010

Calpains and caspases are ubiquitous cysteine proteases that are associated with a variety of cellular pathways. Calpains are involved in processes such as long term potentiation, cell motility and apoptosis, and have been shown to cleave non-erythroid (brain) α- and β-spectrin and erythroid β-spectrin. The cleavage of erythroid α-spectrin by calpain has not been reported. Caspases play an important role in the initiation and execution of apoptosis, and have been shown to cleave non-erythroid but not erythroid spectrin. We have studied the effect of spectrin fragments on calpain and caspase activities. The erythroid and non-erythroid spectrin fragments used were from the N-terminal region of α-spectrin, and C-terminal region of β-spectrin, both consisting of regions involved in spectrin tetramer formation. We observed that the all spectrin fragments exhibited a concentration-dependent inhibitory effect on calpain, but not caspase activity. It is clear that additional studies are warranted to determine the physiological significance of calpain inhibition by spectrin fragments. Our findings suggest that calpain activity is modulated by the presence of spectrin partial domains at the tetramerization site. It is not clear whether the inhibitory effect is substrate specific or is a general effect. Further studies of this inhibitory effect may lead to the identification and development of new therapeutic agents specifically for calpains, but not for caspases. Proteins/peptides with a coiled coil helical conformation should be studied for potential inhibitory effects on calpain activity.
Time Courses of Adaptation in Lumbar Extensor Performance of Patients With a Single-Level Microdiscectomy During a Physical Therapy Exercise Program
Authors: Flanagan Sean P. , Kulig Kornelia ,   PTClinResNet
Published: May 2010

Study Design

Longitudinal single-cohort study.

Objective

To characterize the time course of performance adaptations during a postsurgical exercise intervention following a single-level microdiscectomy.

Background

Patients with a recent history of lumbar microdiscectomy are functionally limited, weak, have compromised paraspinal musculature, and benefit from an exercise program.

Methods

Patients (n = 48) with a single-level microdiscectomy participated in a 12-week (36 sessions) comprehensive strength and endurance exercise program starting 4 to 6 weeks postsurgery. Lumbar extensor strength was quantified as the degree from horizontal on a modified Sorensen test procedure. Patients unable to assume the horizontal position were assumed to have strength deficits. Lumbar muscular endurance performance was quantified by the amount of time patients could hold the Sorensen test position at the horizontal. The time rate of lumbar muscular endurance adaptations were analyzed using longitudinal growth curve modeling.

Results

The adherence rate of this program was low (67%). Twenty percent of the patients were identified as having strength deficits. These deficits were corrected in all patients within 3 to 9 weeks. Linear mixed-model results suggest an improvement of 5.6 seconds in hold time per week of exercise. Both the initial level of endurance and the rates of improvements were highly individualized.

Conclusion

The time course of musculoskeletal performance adaptations in persons with a history of lumbar surgery is highly individualized. When compared to normative endurance times, the results of this study indicate that the number of sessions and duration of therapy needed to generate meaningful adaptations of the paraspinal musculature is longer than what is typically provided in the clinic postsurgery.

Level of Evidence

Therapy, level 4. J Orthop Sports Phys Ther 2010;40(6):336–344. doi:10.2519/jospt.2010.3141
Effects of Recovery Method After Exercise on Performance, Immune Changes, and Psychological Outcomes
Authors: Stacey Douglas L. , Gibala Martin J. , Martin Ginis Kathleen A. , Timmons Brian W.
Published: May 2010

Study Design

Randomized controlled trial using a repeated-measures design.

Objectives

To examine the effects of commonly used recovery interventions on time trial performance, immune changes, and psychological outcomes.

Background

The use of cryotherapy is popular among athletes, but few studies have simultaneously examined physiological and psychological responses to different recovery strategies.

Methods

Nine active men performed 3 trials, consisting of three 50-kJ “all out” cycling bouts, with 20 minutes of recovery after each bout. In a randomized order, different recovery interventions were applied after each ride for a given visit: rest, active recovery (cycling at 50 W), or cryotherapy (cold tub with water at 10°C). Blood samples obtained during each session were analyzed for lactate, IL-6, total leukocyte, neutrophil, and lymphocyte cell counts. Self-assessments of pain, perceived exertion, and lower extremity sensations were also completed.

Results

Time trial performance averaged 118 ± 10 seconds (mean ± SEM) for bout 1 and was 8% and 14% slower during bouts 2 (128 ± 11 seconds) and 3 (134 ± 11 seconds), respectively, with no difference between interventions (time effect, P≤.05). Recovery intervention did not influence lactate or IL-6, although greater mobilization of total leukocytes and neutrophils was observed with cryotherapy. Lymphopenia during recovery was greater with cryotherapy. Participants reported that their lower extremities felt better after cryotherapy (mean ± SEM, 6.0 ± 0.7 out of 10) versus active recovery (4.8 ± 0.9) or rest (2.8 ± 0.6) (trial effect, P≤.05).

Conclusions

Common recovery interventions did not influence performance, although cryotherapy created greater immune cell perturbation and the perception that the participants' lower extremities felt better.

Level of Evidence

Performance enhancement, level 2b. J Orthop Sports Phys Ther 2010;40(10):656–665.doi:10.2519/jospt.2010.3224
Standardization of Adverse Event Terminology and Reporting in Orthopaedic Physical Therapy: Application to the Cervical Spine
Authors: Carlesso Lisa C. , MacDermid Joy C. , Santaguida Lina P.
Published: May 2010

Synopsis

Orthopaedic physical therapy is considered safe, based on a lack of reported harms. Most of the research until now has focused on benefits. Consideration of benefits and harm involves informed consent, clinical decision making, and cost-benefit analyses. Benefits and harms are treatment and dosage specific. There is currently an insufficient number of dosage trials in orthopaedic physical therapy to identify optimal dosage for common interventions, including exercise and manual therapy. Published cases of severe adverse events following chiropractic manipulation illustrate the need for physical therapy to have high-quality data documenting the safety of orthopaedic physical therapy, including cervical manipulation. A recent systematic review identified poor reporting standards of harms within clinical research in this area. Lack of standardization of terminology has contributed to this problem. Pharmacovigilence provides a framework for terms that orthopaedic physical therapy can adapt and thereafter adopt into clinical practice and research. Adverse events are unexpected events that occur following an intervention without evidence of causality. Where temporality of an event is highly suggestive of causality, the term “adverse reaction” may be more appropriate. Future studies in orthopaedic physical therapy should adopt the CONSORT statement extension on the reporting of harms, published in 2004, to ensure better reporting. Consistent reporting of harms in both research and clinical practice requires professional consensus on terminology pertaining to harms, as well as defining what constitutes an adverse event or an adverse reaction. Widespread consultation and consensus should support optimal definitions and processes and facilitate their implementation into practice. This paper is focused on theoretical considerations and evidence in terms of harm reporting within physical therapy using cervical manual therapy as an example. J Orthop Sports Phys Ther 2010;40(8):455–463. doi:10.2519/jospt.2010.3229
Northern Exposure: Resistance to Naval Impressment in British North America, 1775–1815
Authors: Mercer Keith
Published: May 2010

Abstract:

Focusing on resistance, this article examines naval impressment in British North America from 1775 to 1815. Although neglected in Canadian historiography, press gangs sparked urban unrest and political turmoil in seaports such as Halifax, St John's, and Quebec City. Impressment reached into most coastal areas of British North America by the early nineteenth century and its sailors and inhabitants employed a range of strategies to resist it. They also confronted it directly, sometimes with violent results. Press gang riots in St John's in 1794 and Halifax in 1805 led to a prohibition on impressment on shore for much of the Napoleonic Wars. Popular protest served as the catalyst for official resistance to the British Navy and had a lasting impact on civil–naval relations in the North Atlantic world. While the study of popular disturbances in Canadian history usually begins in the mid-nineteenth century, this paper shows that they were important in earlier generations as well. This was often the result of tensions caused by imperial warfare and quarrels with military personnel.
An Affinity for Philosophy: The Absurdoid Theatre of Géza Páskándi
Authors: Morse Donald E.
Published: May 2010

Géza Páskándi (1933–5) coined the term “absurdoid” in order to distinguish his plays from the absurd plays of the west. “In the absurdoid the human being is not simply a blind tool of the impossible situation but … himself is its accomplice,” he argued (Esszék 99). His four plays discussed here, Todogar Jaur Kvárna, No Conductor, The Line, and The Avenger, The Gatekeeper, or It Is Requested That You Wipe Your Feet combine the fantastic with linguistic invention, emotional appeal, and clear moral standards. Through his unique form of absurd theatre, Páskándi courageously attacks the baneful living conditions, omnipresent double-think, and widespread complicity occasioned by brutal dictatorships, especially that of Nicolae Ceauşescu, which he experienced first-hand in his native Transylvania, now part of Romania.
Molecular Dynamics Study of Interaction between Corrosion Inhibitors, Nanoparticles, and Other Minerals in Hydrated Cement
Authors: Liu Yajun , Shi Xianming
Published: May 2010

How NaNO2 corrosion inhibitors and water molecules interact with nanoparticles and other minerals in hydrated cement is investigated at the nanoscale, with a focus on the dynamic behavior of inhibitors in the pore solution at different length and timescales. Representative minerals in hydrated cement (ettringite, Friedel's salt, jennite, kuzelite, portlandite, and tobermorite) and nanoparticles (Al2O3, Fe2O3, SiO2, and TiO2) are computationally studied. The parameters for potential functions of NO2-necessary to describe interactions are evaluated from inverse parameterization. The focus is on the structure of nanoparticles, minerals, and water molecules near the solution–solid interface. Information on interactions of aqueous species with their surroundings is retrieved by molecular dynamics simulations, which provide insight into dynamic behaviors around the solution–solid interfaces. Further analysis reveals that the solid surfaces have a strong effect on the dynamic behaviors of corrosion inhibitors.
Nanotechnology and Concrete
Authors: Porro Antonio , Dolado Jorge S. , Gaitero Juan J. , Manzano Hegoi
Published: May 2010

The structure of cement derivatives (cement-based materials) is complex and not fully understood. They are formed by self-assembly of different chemical species in a specific way to form basic building blocks (or units); the size of these units is on the order of a few nanometers. After they are formed, these basic units arrange themselves into larger units, still nano-metric in size, which constitute the cementitious matrix. The distinctive macroscopic properties of cementitious materials arise from their unique structural arrangement. This paper is an introduction to the results obtained by the Centre for Nanomaterials Applications in Construction over the past 5 years. The approach used in this study is a combination of experimental and numerical (multiscale simulation) techniques. On the one hand, the study shows how the addition of nanosilica particles can modify the mechanical properties of the cement matrix as well as its resistance to the calcium leaching process. On the other hand, the study illustrates how computational modeling is a valuable tool for gaining insight into the complex calcium silicate hydrate nanostructure and for designing improved cementitious materials.
Editor's Introduction: Medium and Message in German Modernism
Authors: Pfau Thomas
Published: May 2010

Even a cursory glance at the artistic projects and aesthetic conceptions that take shape in the German-speaking parts of Central Europe between 1890 and 1930 and that have since come to be viewed as indispensable to an understanding of German Modernism will yield an enormous variety of projects. From the early expressionist projects of the Brücke and the Viennese Sezession to the brutally satiric and anti-aestheticist indictments of a bankrupt bourgeois culture in Georg Grosz, Otto Dix, or Max Beckmann in the visual arts; from the second Viennese School of Schoenberg, Berg, Webern to the unique amalgamation of seemingly disparate and often brilliantly adaptive styles in late-or avowedly post-Romantic composers such as Mahler, Berg, Zemlinski, Korngold, or Kurt Weill; and from the post-Humanism of such dissimilar figures as the post-Nietzschean pessimist Oswald Spengler and the only slightly more upbeat projects of Max Weber and Georg Simmel to the epigrammatic concision of Karl Kraus and Ludwig Wittgenstein, German Modernism, characterized by a propensity for manifesto-style self-authorization, claims programmatic status for itself even is it comprises enormously diverse and distinctive figures.
Editor's Introduction: Modernism and the Everyday
Authors: McCracken Scott
Published: May 2010

Sitting in the first of the two sessions on the everyday at the fifth Modernist Studies Association conference in Birmingham, England my thoughts, stimulated by three engaging papers, also ranged over more mundane matters. This was no reflection on the papers themselves. For what does modernist prose teach us if not the capacity of consciousness to think of more than one thing at a time. I was momentarily distracted by the sight of a well-known critic's leather jacket and began musing on the symbolism of that familiar item of academic clothing. That worn by a famous Marxist critic, I was once told by my leather-jacketed PhD supervisor, had an audible authority. It creaked. The comment was, I reflected, moving further into my reverie, the kind of sartorial criticism that is sadly absent from contemporary research training programmes.
“Just Looking” at the Everyday: Marianne Moore's Exotic Modernism
Authors: Bazin Victoria
Published: May 2010

Victoria Bazin (Northumbria University) argues that Marianne Moore was a connoisseur of modern clutter, drawing on the historical residues of “antiques, rare art objects and ancient artefacts”, but also the disorder of the information age: the disaggregated fragments thrown up by contemporary journalism. Moore takes the discursive production of China in the “Illustrated News” and creates a constellation, after Benjamin, that goes further than the confirmation of the West as “a superior site of knowledge” to gesture to something beyond a technocratic modernity.
Antifungal Effect of (+)-Pinoresinol Isolated from Sambucus williamsii
Authors: Hwang Bomi , Lee Juneyoung , Liu Qing-He , Woo Eun-Rhan , Lee Dong Gun
Published: May 2010

In this study, we investigated the antifungal activity and mechanism of action of (+)-pinoresinol, a biphenolic compound isolated from the herb Sambucus williamsii,used in traditional medicine. (+)-Pinoresinol displays potent antifungal properties without hemolytic effects on human erythrocytes. To understand the antifungal mechanism of (+)-pinoresinol, we conducted fluorescence experiments on the human pathogen Candida albicans. Fluorescence analysis using 1,6-diphenyl-1,3,5-hexatriene (DPH) indicated that the (+)-pinoresinol caused damage to the fungal plasma membrane. This result was confirmed by using rhodamine-labeled giant unilamellar vesicle (GUV) experiments. Therefore, the present study indicates that (+)-pinoresinol possesses fungicidal activities and therapeutic potential as an antifungal agent for the treatment of fungal infectious diseases in humans.
The Reaction of Cyanoacetylhydrazine with ω-Bromo(4-methyl)acetophenone: Synthesis of Heterocyclic Derivatives with Antitumor Activity
Authors: Mohareb Rafat M. , Mohamed Abeer A.
Published: May 2010

New approaches for the synthesis of hydrazide-hydrazone derivatives were demonstrated as well as some heterocyclizations of such derivatives to afford 1,3,4-triazine, pyridine and 1,3,4-oxadiazine derivatives. The antitumor evaluation of the newly synthesized products against three cancer cell lines, namely breast adenocarcinoma (MCF-7), non-small cell lung cancer (NCI-H460) and CNS cancer (SF-268) were recorded. Most of the synthesized compounds showed high inhibitory effects.
Beliefs and Attitudes toward Vegetarian Lifestyle across Generations
Authors: Pribis Peter , Pencak Rose C , Grajales Tevni
Published: May 2010

The objective of the study was to examine whether reasons to adopt vegetarian lifestyle differ significantly among generations. Using a Food Frequency Questionnaire (FFQ), we identified that 4% of the participants were vegans, 25% lacto-ovo-vegetarians, 4% pesco-vegetarians and 67% non-vegetarian. Younger people significantly agreed more with the moral reason and with the environmental reason. People ages 41–60 significantly agreed more with the health reason. There are significant differences across generations as to why people choose to live a vegetarian lifestyle.
Targeted Therapy of Cancer Using Photodynamic Therapy in Combination with Multi-faceted Anti-Tumor Modalities
Authors: Olivo Malini , Bhuvaneswari Ramaswamy , Lucky Sasidharan Swarnalatha , Dendukuri Nagamani , Soo-Ping Thong Patricia
Published: May 2010

Photodynamic therapy (PDT) has emerged as one of the important therapeutic options in the management of cancer and other diseases. PDT involves a tumor-localized photosensitizer (PS), which when appropriately illuminated by visible light converts oxygen into cytotoxic reactive oxygen species (ROS), that attack key structural entities within the targeted cells, ultimately resulting in necrosis or apoptosis. Though PDT is a selective modality, it can be further enhanced by combining other targeted therapeutic strategies that include the use of synthetic peptides and nanoparticles for selective delivery of photosensitizers. Another potentially promising strategy is the application of targeted therapeutics that exploit a myriad of critical pathways involved in tumorigenesis and metastasis. Vascular disrupting agents that eradicate tumor vasculature during PDT and anti-angiogenic agents that targets specific molecular pathways and prevent the formation of new blood vessels are novel therapeutic approaches that have been shown to improve treatment outcome. In addition to the well-documented mechanisms of direct cell killing and damage to the tumor vasculature, PDT can also activate the body’s immune response against tumors. Numerous pre-clinical studies and clinical observations have demonstrated the immuno-stimulatory capability of PDT. Herein, we aim to integrate the most important findings with regard to the combination of PDT and other novel targeted therapy approaches, detailing its potential in cancer photomedicine.
Modeling Methane Emission from Wetlands in North-Eastern New South Wales, Australia Using Landsat ETM+
Authors: Akumu Clement E. , Pathirana Sumith , Baban Serwan , Bucher Daniel
Published: May 2010

Natural wetlands constitute a major source of methane emission to the atmosphere, accounting for approximately 32 ± 9.4% of the total methane emission. Estimation of methane emission from wetlands at both local and national scale using process-based models would improve our understanding of their contribution to global methane emission. The aim of the study is to estimate the amount of methane emission from the coastal wetlands in north-eastern New South Wales (NSW), Australia, using Landsat ETM+ and to estimate emission with a temperature increase. Supervised wetland classification was performed using the Maximum Likelihood Standard algorithm. The temperature dependent factor was obtained through land surface temperature (LST) estimation algorithms. Measurements of methane fluxes from the wetlands were performed using static chamber techniques and gas chromatography. A process-based methane emission model, which included productivity factor, wetland area, methane flux, precipitation and evaporation ratio, was used to estimate the amount of methane emission from the wetlands. Geographic information system (GIS) provided the framework for analysis. The variability of methane emission from the wetlands was high, with forested wetlands found to produce the highest amount of methane, i.e., 0.0016 ± 0.00009 teragrams (Tg) in the month of June, 2001. This would increase to 0.0022 ± 0.0001 Tg in the month of June with a 1 °C rise in mean annual temperature by the year 2030 in north-eastern NSW, Australia.
Governing for Sustainable Coasts: Complexity, Climate Change, and Coastal Ecosystem Protection
Authors: Craig Robin Kundis , Ruhl J.B.
Published: May 2010

The world’s coastal ecosystems are among the most complex on Earth, and they are currently being governed unsustainably, by any definition. Climate change will only add to this complexity, underscoring the necessity of finding new ways to govern for these ecosystems’ sustainable use. After reviewing the problems facing coastal ecosystems and innovations in their governance, this article argues that governance of coastal ecosystems must move to place-based adaptive management regimes that incorporate innovative and flexible regulatory mechanisms, such as market-based incentives.
Some Sustainability Aspects of Energy Conversion in Urban Electric Trains
Authors: Nicola Doru A. , Rosen Marc A. , Bulucea Cornelia A. , Brandusa Constantin
Published: May 2010

The paper illustrates some aspects of energy conversion processes during underground electric train operation. Energy conversion processes are explained using exergy, in order to support transport system sustainability. Loss of exergy reflects a loss of potential of energy to do work. Following the notion that life in Nature demonstrates sustainable energy conversion, we approach the sustainability of urban transportation systems according to the model of an ecosystem. The presentation steps based on an industrial ecosystem metabolism include describing the urban electric railway system as an industrial ecosystem with its limits and components, defining system operation regimes, and assessing the equilibrium points of the system for two reference frames. For an electric train, exergy losses can be related to the energy flows during dynamic processes, and exergy conversion in these processes provides a meaningful measure of the industrial (i.e., transportation) ecosystem efficiency. As a validation of the theoretical results, a case study is analyzed for three underground urban electric train types REU-U, REU-M, REU-G operating in the Bucharest Underground Railway System (METROREX). The main experimental results are presented and processed, and relevant diagrams are constructed. It is determined that there is great potential for improving the performance of rail systems and increasing their sustainability. For instance, power converters and efficient anti-skid systems can ensure optimum traction and minimum electricity use, and the recovered energy in electric braking can be used by other underground trains, increasing exergy efficiency, although caution must be exercised when doing so to avoid reducing the efficiency of the overall system.
Synthesis of some novel hydrazono acyclic nucleoside analogues
Authors: Soltani Rad Mohammad N , Khalafi-Nezhad Ali , Behrouz Somayeh
Published: May 2010

The syntheses of novel hydrazono acyclic nucleosides similar to miconazole scaffolds are described. In this series of acyclic nucleosides, pyrimidine as well as purine and other azole derivatives replaced the imidazole function in miconazole and the ether group was replaced with a hydrazone moiety using phenylhydrazine. To interpret the dominant formation of (E)-hydrazone derivatives rather than (Z)-isomers, PM3 semiempirical quantum mechanic calculations were carried out which indicated that the (E)-isomers had the lower heats of formation.
Recruiting and Retaining Teachers: Turning Around the Race to the Bottom in High-Need Schools
Authors: Darling-Hammond Linda
Published: May 2010

What is it that keeps some people in teaching and chases others out? What can be done to increase the power of the teaching profession to recruit and retain effective teachers and to create a stable, expert teaching force in all kinds of districts? This issue of the Journal of Curriculum and Instruction explores these questions from a number of different angles, illuminating a range of strategies that can be used to address them. In this article, I examine the central factors affecting teacher recruitment and retention in high-need schools, and the strategies that have been found to be effective in getting and keeping high-quality teachers in the neediest communities.
The Case for Differentiated Professional Support: Toward a Phase Theory of Professional Development
Authors: Gabriel Rachael
Published: May 2010

In this perspective article I draw upon interviews with first-, second-, and third-year teachers to develop a phase theory of professional development that accounts for the questions, interests, and preferences of teachers across their first three years in the classroom. I suggest that differentiated professional development has potential to improve the quality of the teaching force by increasing the expertise of teachers in their first few years and providing support that is engaging and rewarding enough to encourage retention.
Modelización del proceso de austenización de un acero eutectoide
Authors: Caballero F. G. , Capdevila C. , García de Andrés C.
Published: May 2010

En este trabajo se ha desarrollado un modelo matemático para el cálculo de la cinética de formación de austenita a partir de perlita en un acero eutectoide en condiciones de calentamiento continuo. En dicho modelo, se ha aplicado, con éxito, la ecuación de Avrami para calcular la fracción de volumen de la austenita formada en condiciones no isotérmicas. La influencia de parámetros tales como el espaciado interlaminar, la longitud de borde de colonia de perlita y la velocidad de calentamiento sobre la cinética de formación de austenita, ha sido estudiada experimentalmente y considerada en la modelización. Se ha comprobado que la cinética de formación de austenita es más lenta cuanto más grosera es la perlita inicial y más alta es la velocidad de calentamiento. Asimismo, las temperaturas de inicio y final de la transformación aumentan ligeramente con la velocidad de calentamiento, aunque las temperaturas finales son más sensibles a este parámetro. Los resultados experimentales para la fracción de volumen de austenita y temperaturas críticas de la transformación perlita-austenita coinciden en gran medida con los valores predichos por el modelo propuesto en este trabajo, siendo la fiabilidad mayor del 90 % en factor de correlación al cuadrado.
Recuperación mediante extracción con disolventes de vanadio de soluciones procedentes de la lixiviación de catalizadores agotados empleando Primene 81R
Authors: Lozano L. J. , García J.
Published: May 2010

En el presente trabajo se ha estudiado la recuperación del vanadio contenido en soluciones procedentes del proceso de lixiviación de catalizadores agotados, por medio de la técnica de extracción con disolventes, empleando la amina primaria PRIMENE 81R, planteando un proceso industrial multietapa para el tratamiento de estos efluentes. Los resultados obtenidos permiten proponer un mecanismo de extracción para el vanadio(V), con esta amina en medio ácido, verificando la gran influencia del pH en el proceso y Ajando los rangos adecuados para las siguientes variables: relación O/A, composición de la fase orgánica, pH, velocidad de agitación y velocidad de separación de fases. Esos valores se simularon en condiciones industriales. El vanadio se recupera finalmente precipitándolo como metavanadato amónico y posterior calcinación para obtener pentóxido de vanadio de calidad comercial.
Efecto de la implantación iónica de cerio y lantano en la corrosión del acero galvanizado
Authors: Arenas M. A. , Rodríguez R. , De Damborenea Juan J.
Published: May 2010

En el presente trabajo se han observado las variaciones en la morfología superficial y se han estudiado los cambios en el comportamiento frente a la corrosión, inducidos en el acero galvanizado modificado mediante la implantación iónica con cerio y lantano. Las dosis de implantación ensayadas fueron 1x1016 iones/cm2 de Ce+, 2x1016 iones/cm2 de Ce+ y 2x10 16 iones/cm2 de La+, siendo la energía de implantación de 150 KeV y la incidencia normal. El estudio del aspecto de la superficie mediante microscopía electrónica de barrido reveló que las muestras implantadas con lantano sufrían los mayores cambios superficiales. En estas muestras se observa una estructura vermicular totalmente diferente a la distribución de granos hexagonales con segregación de plomo en las fronteras de grano y en el interior de los mismos, presentada por el acero galvanizado sin implantar. Por el contrario, al implantar con cerio, el único efecto que se apreció fue la desaparición parcial o completa, dependiendo de la dosis de implantación, de los precipitados de plomo. Las curvas de polarización en NaCl 3,56 % indicaron que la implantación mejora la resistencia a la corrosión del acero galvanizado sin implantar, disminuyéndose en un orden de magnitud la densidad de corriente de corrosión para las muestras implantadas con lantano.
El personal científico del CENIM frente al reto de las publicaciones científicas: los años 1995-1999
Authors: Alguacil F. J. , Carsí M. , Ruano O. A.
Published: May 2010

En este trabajo se analiza la labor del personal investigador del Centro Nacional de Investigaciones Metalúrgicas (CENIM) en cuanto a publicaciones correspondientes al período 1995-99.
Influencia de las adiciones de TaC y NbC en las propiedades de los aceros rápidos pulvimetalúrgicos M3/2
Authors: Gordo E. , Velasco E. , Martínez M. A. , Torralba J. M.
Published: May 2010

Este trabajo plantea la fabricación de materiales compuestos de matriz metálica, basados en el acero rápido M3/2 y reforzados con distintas cantidades de NbC y TaC, mediante técnicas convencionales pulvimetalúrgicas (P/M): mezcla, compactación y sinterización. Al acero rápido se añadió grafito para compensar las pérdidas de carbono durante la sinterización y cupro-fósforo para promover sinterización en fase líquida, constituyendo esta mezcla el material base. Los polvos de carburos y de material base fueron mezclados en seco y compactados uniaxialmente a 700 MPa. Tras esta etapa, se realizó la sinterización en vacío a dos temperaturas: 1.190 °C y 1.230 °C. Todos los materiales sinterizados fueron caracterizados mediante el estudio de las propiedades mecánicas, el comportamiento a desgaste y un amplio análisis microestructural.
Efecto protector de las capas de productos de corrosión de exposición atmosférica
Authors: Hernández L. S. , Miranda J. M. , Domínguez O.
Published: May 2010

Las técnicas electroquímicas de seguimiento del potencial de corrosión (Ecorr), resistencia de polarización (Rp) y polarización potenciodinámica, se utilizaron para evaluar la capacidad de protección de las capas de productos de corrosión formadas sobre acero de bajo carbono, cinc (acero galvanizado), cobre y aluminio, después de 1, 2 y 5 años de exposición en una atmósfera urbana. Los resultados obtenidos, utilizando una solución 0,1 M de Na2SO4, indican una mayor protección anticorrosiva de los cuatro materiales metálicos como resultado de la formación de los productos de corrosión. Además, se observó que al aumentar la exposición a la intemperie, los valores de Ecorr fueron más nobles, los de Rp aumentaron y las curvas anódicas de polarización potenciodinámica mostraron mayor polarización y se desplazaron a la zona de menor densidad de corriente en los diagramas E vs log i. Estos resultados no tuvieron un acuerdo total con los obtenidos por pérdida de peso.
Tendencia actual y desarrollos futuros de nuevos controles basados en la lógica borrosa y su aplicación al mecanizado a alta velocidad
Authors: Haber R. E. , Alique A. , Alique J. R. , Haber-Haber R. , Ros S.
Published: May 2010

El mecanizado a alta velocidad (MAV) exige nuevos conceptos y estrategias de diseño mecánico de los elementos de las máquinas herramienta, así como el rediseño de todos los aspectos relacionados con los sistemas de control, desde los accionamientos hasta el CNC (integración de sensores, procesamiento y filtrado de señales, algoritmos de control de posición, velocidad y trayectoria), con vistas a obtener prestaciones superiores. En este trabajo se ofrece un estado del arte, con algunos de los hitos más importantes en el área del control aplicado al proceso de mecanizado a alta velocidad. Así, se intentan resumir algunas de las prestaciones más importantes de los nuevos sistemas de control y proponer hacia donde se deben dirigir los esfuerzos principales en los años venideros. Se hace énfasis en los accionamientos lineales y en sus características, que lo convierten en ideal para el MAV. De igual modo, y como aspecto novedoso, se proponen algunos esquemas de control borroso que han tenido éxito en la regulación de procesos no lineales y complejos y que pueden encontrar aplicación en los nuevos servosistemas, estrategias de compensación térmica, sistemas de regulación del fluido de corte y sistemas para optimizar la tasa de arranque de virutas, sólo por citar algunos ejemplos. De esta manera, no sólo es posible aumentar la productividad sino también mejorar el funcionamiento de la máquina herramienta en su conjunto. Por otra parte, se hacen una serie de propuestas de campos abiertos para desarrollos futuros, partiendo del estudio de los logros alcanzados por algunos fabricantes en el diseño de máquinas-herramienta y CNC. Finalmente, se destacan las características de los controladores jerárquicos y algunas de las prestaciones que se pueden alcanzar sin necesidad de grandes modificaciones tecnológicas en la máquina herramienta y considerando un mercado cada vez más dominado por los CNC abiertos.
Detección, identificación y clasificación de defectos usando RNA y un manipulador robótico de 2 G.L (algoritmos Kohonen y MLP)
Authors: Barrera G. , Fabián M. A. , Ugalde C. A.
Published: May 2010

La técnica de inspección ultrasónica por inmersión ha tenido un desarrollo sostenido desde la década de los 80 y tiene muchas ventajas en comparación con la técnica de contacto. Se presenta una solución flexible y de bajo costo basada en instrumentación virtual para el control de un servomecanismo de exploración ultrasónica (manipulador), por la técnica de inmersión. El sistema desarrollado hace uso de un ordenador personal (PC), del sistema operativo Windows, de software de instrumentación virtual Lab VIEW, de tarjetas de adquisición de datos (DAQ) y de una tarjeta GP113. Como solución al problema de la detección, clasificación y evaluación de defectos se propone un sistema experto basado en la técnica de redes neuronales artificiales por medio de la interpretación de las señales acústicas (ecos) obtenidas por mediante la técnica de inspección ultrasónica de inmersión. Se proponen dos redes neuronales: Kohonen y Perceptron Multicapas (MLP). Estas técnicas permiten modelar procesos no lineales complejos con una gran exactitud. Tanto las operaciones de control del manipulador de 2 grados libertad, adquisición y tratamiento de los datos y la fase de entrenamiento de las redes se llevó a cabo en un ambiente de instrumentación virtual utilizando Lab VIEW y DataEngine.
Modelización de la formación isotérmica de ferrita idiomórfica en aceros de medio carbono microaleados con vanadio-titanio
Authors: Capdevila C. , Caballero E. G. , García de Andrés C.
Published: May 2010

En este trabajo se presenta un modelo teórico para calcular la evolución con el tiempo de la transformación isotérmica de la austenita en ferrita idiomórfica en un acero de medio carbono microaleado con vanadio-titanio. En dicho modelo, desarrollado en base al estudio de la cinética de nucleación y crecimiento de ferrita idiomórfica, se ha valorado la influencia de la naturaleza, tamaño y distribución de las inclusiones responsables de la nucleación intragranular de ferrita. Así mismo, se ha analizado, con detenimiento, la influencia que tiene el tamaño de grano austenítico. El modelo ha sido validado experimentalmente, mostrándose un excelente acuerdo (85 % en R ) entre los resultados experimentales y los predichos por el modelo de transformación propuesto en este trabajo.
Transporte facilitado mediante aminas de Au(CN)2 y otros complejos metálicos cianurados
Authors: Alguacil F. J.
Published: May 2010

Se estudia el empleo de las aminas Hostarex A327, Amberlite LA2 y Primene JMT (terciaria, secundaria y primaria, respectivamente) como reactivos del transporte facilitado, con membranas líquidas soportadas, de complejos metálicos cianurados, con especial atención al caso del oro. También se estudia la adición de derivados organofosforados neutros (bases de Lewis) a la fase orgánica de la amina, como agentes sinérgicos del transporte de Au(CN) )2, a pH alcalinos, y de forma selectiva frente a otros complejos metálicos cianurados.
Recubrimiento de Stellite 6 sobre acero inoxidable realizado con láser de CO2 para válvulas de escape de motores diesel
Authors: Cadenas M. , Cuetos J. M. , Fernández J. E. , Fernández M. R. , Vega L. M. , De Damborenea J.
Published: May 2010

Para abaratar el coste de recuperación o sustitución de válvulas de escape en motores diesel, estas se fabrican con un material base económico, recubriéndose el asiento de la válvula con otro material al que se exigirá elevada dureza y buena resistencia al impacto, a la corrosión y al desgaste erosivo en caliente (>550 °C) y sin lubricación. Partiendo de esta idea, en el presente trabajo se han determinado los parámetros adecuados para realizar, mediante la técnica de plaqueado láser, un recubrimiento con Stellite 6, sobre sustratos de acero AISI 304 (probetas planas) y SAE EV8 (válvulas reales). Sobre las válvulas, se depositaron uno y dos cordones superpuestos, se minimizó la presencia de poros y grietas, modificando el grado de solape inicial y final de los cordones circulares y la potencia en función del ángulo girado. Así, se consiguieron cordones de espesor uniforme. Tras los tratamientos, se estudiaron la dureza, dilución y microestructura final de los distintos recubrimientos, observándose, en los cordones sobre probetas planas, diluciones del 10 % y durezas de 550 HV, mientras que, en las válvulas con un cordón, eran del 25 % y 430 HV, respectivamente. Con dos cordones superpuestos, la dureza llegaba a 470 HV en el cordón superior.
Sociability Heuristics for Evaluating Social Interactive Television Systems
Authors: Geerts David
Published: May 2010

In this chapter, the author introduces 12 heuristics for evaluating the sociability of social interactive television systems. He first introduce the social uses of television, documented by many scholars in media studies, as well as the relatively new concept of sociability in new technologies. He then explain how the heuristics are based on a thorough analysis of several user studies the author performed with several social interactive television systems, as well as of literature that reports lab studies and field studies with such systems. Finally, each heuristic is presented and explained in more detail, along with some more specific guidelines. Geerts hopes these heuristics will enable designers and evaluators of social interactive television systems to make sure they support the social uses of television and create sociable systems.
Asynchronous Communication
Authors: Amento Brian , Harrison Chris , Nathan Mukesh , Terveen Loren
Published: May 2010

With the advent of digital video recorders and video-on-demand services, the way in which we consume media is undergoing a fundamental change. People today are less likely to watch shows at the same time, let alone the same place. As a result, television viewing which was once a social activity has been reduced to a passive, isolated experience. CollaboraTV was designed to address this new mode of television viewing by directly supporting asynchronous communication. We demonstrated its ability to support this communal viewing experience through a lab study and a month-long field study. Our studies show that users understand and appreciate the utility of asynchronous interaction, are enthusiastic about CollaboraTV’s engaging social communication primitives and value implicit show recommendations from friends. Our results both provide a compelling demonstration of a social television system and raise new challenges for social television communication modalities.
From 2BeOn Results to New Media Challenges for Social (i)TV
Authors: Abreu Jorge Ferraz , Almeida Pedro
Published: May 2010

This chapter focuses on traditional and emergent challenges for the Social (i)TV area focusing on explaining the development and evaluation of one of the first Social iTV prototypes and looking at the challenges new media is introducing to this research field. The authors begin by explaining the conceptualization, development and evaluation process of the 2BeOn system and continue with the most important results from it’s evaluation with a particular focus on the results that can be important when developing any Social iTV platform. In the last part of the chapter recent developments in the broadcast of TV and Audiovisual content, namely considering the Internet as a medium, are addressed. In this scope authors propose a categorization of emergent online distribution platforms along with a set of social activities users perform on those platforms. Taking in consideration some of the challenges surrounding the presented scenario the chapter ends with the conceptualization of UMCA, a system that could increase social interaction activities performed during the consumption of online AV/TV content.