bluuebunny/crossref_metadata_2025 huggingface dataset:
Addressing Educational Challenges in Veterinary Medicine through the use of Distance Education
Authors: Murray Amanda L , Sischo William M
Published: January 2008

The veterinary profession is currently facing many educational challenges, including an insufficient capacity to train and educate veterinarians for the multiple disciplines within the profession, a shortage of veterinarians in private and public practice, a shortage of faculty, a lack of human and professional diversity, and a rising cost of education resulting in extreme student debt loads. As a methodology for teaching, distance education (DE) has the potential to address many of these issues. By its very nature, DE can increase the capacity of current facilities and faculty. In addition, DE can allow students to acquire the necessary knowledge at less cost. This article describes a model for incorporating DE in the form of interactive Web-based courses, in conjunction with short, intensive residential programs, for the lecture portions of courses taught in the pre-veterinary, veterinary, and post-veterinary educational periods. In this model, the Web-based courses are used to convey the necessary core knowledge required at each step of the educational process. The residential portions are then used to apply the knowledge in such a way as to combine clinical applications with research in basic and applied sciences. Distance education can provide increased flexibility, high-quality educational experiences, and a less costly alternative for students while maximizing the reach of current faculty efforts and the capacity of existing physical structures.
Videoconferencing in a Veterinary Curriculum
Authors: Sims Michael H. , Howell Nancy , Harbison Babbet
Published: January 2008

Videoconferencing is a powerful and versatile method for distance learning. Videoconferencing incorporates real-time video and audio into connections with distant sites and, when combined with simultaneous Internet transmission of high-resolution images, enables veterinary educators to expand the classroom to include students and faculty from remote sites. The University of Tennessee College of Veterinary Medicine (UTCVM) has used videoconferencing to deliver and receive entire courses, virtual rounds, seminars, journal clubs, and small meetings and for in-house transmission from one area of the campus to another. Responses from faculty and students at UTCVM indicate that videoconferencing technology will be a permanent part of the academic mission of the college for years to come. This article describes a number of veterinary school applications using distance-learning approaches that the authors hope will serve as examples upon which others can build.
Harnessing Collective Knowledge to Create Global Public Goods for Education and Health
Authors: Bernardo Theresa M.
Published: January 2008

Our global interconnectedness has first been expressed in the transformation of business and entertainment, but it will have profound effects on all aspects of our lives, including education and health. Today's students are accustomed to supplying and consuming user-generated content, such as the videos of YouTube, and to using social networking applications, such as MySpace. This can be turned to their advantage in the development of work skills for the twenty-first century. Central among these skills will be the ability to work in teams that cross disciplinary, cultural, and geographic borders.
Development of Precision Statement for Determining Air Void Characteristics of Fresh Concrete with Use of Air Void Analyzer
Authors: Distlehorst Jennifer A. , Kurgan Geoffrey J.
Published: January 2008

The presence of an adequate air void system is widely regarded as one of the key elements to producing durable, long-lasting concrete. Until recently, the air void system was monitored in the fresh state by a measure of the total air, and an indication of the air void characteristics, namely, the spacing factor and specific surface, was not possible until the concrete hardened. With the development of the air void analyzer (AVA), it is now possible to measure the spacing factor and specific surface of the air voids while the concrete is still in the plastic state. Currently, 14 states own an AVA unit, and numerous other states have investigated implementing the device. As a result of widespread use of this technology, the AASHTO Technology Implementation Group, led by the Kansas Department of Transportation, is working toward possible standardization of this test method. One of the crucial components of this effort is development of a precision statement for the test protocol. In response, a round-robin study consisting of 19 devices and operators was held in February 2006 to gather the necessary data. Through this study, the single operator coefficient of variation (COV) was determined to be 15%. The multiple operator COV was determined to be 19%. The statistical analysis that was performed and the interaction of the devices based on average spacing factor and specific surface are discussed.
Evaluation of Self-Consolidating Concrete for Drilled Shaft Applications at Lumber River Bridge Project, South Carolina
Authors: Brown Dan A. , Schindler Anton K. , Bailey Joseph D. , Goldberg Aaron D. , Camp William M. , Holley Daniel W.
Published: January 2008

Case studies have shown that when conventional concrete mixtures are used in congested drilled shafts, lack of adequate workability or flow between reinforcing bars may lead to trapped laitance or segregation between the inside and outside of the reinforcing cage. Due to its flow-ability and resistance to segregation, self-consolidating concrete (SCC) was evaluated as a viable material to overcome this problem. Several 1.8-m (6-ft) diameter drilled shafts were constructed using SCC as part of a field trial during the Lumber River Bridge Project, South Carolina. Identical shafts were constructed with SCC and a high slump gravel-aggregate concrete mixture typically used in coastal South Carolina. Both mixtures were observed to have excellent workability characteristics. Observations of the hardened concrete from exhumed drilled shafts indicate that generally good performance can be achieved in difficult construction conditions (congested cage, tremie placement, and lengthy placement times) if highly workable concrete is used. Some imperfections in the concrete were observed, even under these closely monitored conditions, and some degree of imperfection in this type of construction appears to be practically unavoidable. The imperfections observed in these field trials were detected by crosshole sonic logging, but they do not appear to have significant adverse consequences for foundation performance. On the basis of results of this project, it is concluded that SCC may be feasible for use in congested drilled shaft applications.
Bulb-T Beams with Self-Consolidating Concrete on Route 33 in Virginia
Authors: Ozyildirim Celik , Davis Rodney T.
Published: January 2008

A study investigated bulb-T beams with self-consolidating concrete (SCC) in the Route 33 Bridge over the Pamunkey River in Virginia, near West Point. Before construction of the bridge, two test beams with SCC similar in cross section to the actual beams in the structure were cast and loaded to failure at FHWA's Turner-Fairbank Highway Research Center in McLean, Virginia. They were tested for transfer length, development length, flexural strength, and shear strength. These test beams demonstrated that SCC members can be designed with the same methods, assumptions, and limiting values as used for normally consolidated concrete beams. On the basis of positive results, beams with SCC were cast and placed in the bridge. It was found that SCC can be prepared yielding adequate slump flow without segregation, satisfactory strength and acceptably low permeability. Attention should be paid to the sensitivity of SCC to water content.
Midwest Guardrail System W-Beam-to-Thrie-Beam Transition
Authors: Polivka Karla A. , Coon Brian A. , Sicking Dean L. , Faller Ronald K. , Bielenberg Robert W. , Rohde John R. , Reid John D.
Published: January 2008

For longitudinal barriers, it is common practice to use a standard W-beam guardrail along the required highway segments and to use a stiffened thrie-beam guardrail in a transition region near the end of a bridge. As a result of the differences in rail geometries, a W-beam-to-thrie-beam transition element is typically used to connect and provide continuity between the two rail sections. However, the W-beam-to-thrie-beam transition element has not been evaluated according to current impact safety standards. Therefore, an approach guardrail transition system, including a W-beam-to-thrie-beam transition element, was constructed and crash tested. The transition system was attached to Missouri's thrie-beam and channel bridge railing system.
Mainstreaming Context-Sensitive Design in Massachusetts
Authors: Paiewonsky Luisa , DiPaolo Thomas A. , Bonsignore Ruth , Larkin Beth , Conklin Christopher
Published: January 2008

In January 2006, the Massachusetts Highway Department issued a new Project Development and Design Guide that dramatically reshaped the way in which transportation projects were implemented throughout the commonwealth. The process and the resulting guide are outstanding examples of mainstreaming principles and objectives of context-sensitive design (CSD) into highway planning and design on a statewide level. This paper explores the history of CSD in Massachusetts, describes the process used to develop and implement the new guide, provides an overview of context-sensitive project development and design guidelines included in the guide, and identifies some conclusions and lessons learned from this experience.
Evaluation of Abutment Scour Prediction Equations with Field Data
Authors: Benedict Stephen T. , Deshpande Nikhil , Aziz Nadim M.
Published: January 2008

The U.S. Geological Survey, in cooperation with FHWA, compared predicted abutment scour depths, computed with selected predictive equations, with field observations collected at 144 bridges in South Carolina and at eight bridges from the National Bridge Scour Database. Predictive equations published in the 4th edition of Evaluating Scour at Bridges (Hydraulic Engineering Circular 18) were used in this comparison, including the original Froehlich, the modified Froehlich, the Sturm, the Maryland, and the HIRE equations. The comparisons showed that most equations tended to provide conservative estimates of scour that at times were excessive (as large as 158 ft). Equations also produced under-predictions of scour, but with less frequency. Although the equations provide an important resource for evaluating abutment scour at bridges, the results of this investigation show the importance of using engineering judgment in conjunction with these equations.
Benefits of Porous Asphalt Overlay on Storm Water Quality
Authors: Barrett Michael E. , Shaw Christopher B.
Published: January 2008

This project documents the impact of a porous asphalt overlay on the quality of highway storm water runoff. A porous asphalt overlay, also known as a permeable friction course (PFC) or open-graded friction course, is a layer of porous asphalt, approximately 50 mm thick, that is often applied on top of conventional asphalt on highways to enhance safety and reduce noise. The quality of storm water runoff from a four-lane divided highway in the Austin, Texas, area was monitored before and after the installation of a PFC. The observed concentrations of total suspended solids and pollutants associated with particulate material were much lower in the runoff from the PFC than that derived from the conventional asphalt surface. Concentration reductions were observed for total suspended solids (92%), total lead (91%), total copper (47%), and total zinc (75%). The concentrations of chemical oxygen demand and total Kjeldahl nitrogen were initially lower in the runoff from the PFC but increased abruptly after about 6 months to concentrations that were similar to the concentrations in the runoff from conventional pavement. The concentrations of dissolved constituents were not significantly different between the two pavement types. The observed concentrations of polycyclic aromatic hydrocarbons were below the detection limit for both pavement types.
Outsourcing Utility Coordination
Authors: Lindly Jay K.
Published: January 2008

Roughly half of the state departments of transportation (DOTs) in the United States have begun using utility coordination consultants to perform routine tasks associated with accommodating and relocating utilities on highway rights-of-way and previously performed only by DOT employees. Consultant involvement is expected to increase significantly because of increased highway construction budgets and capped or reduced numbers of DOT employees. The AASHTO Highway Subcommittee on Right-of-Way and Utilities surveyed its 52 member states in 2006 on the status of their use of utility coordination consultants, and 29 members responded. This paper takes the results of that survey and opinions from transportation professionals expressed at the 2006 AASHTO–FHWA Subcommittee for Right-of-Way and Utilities Conference in Baltimore, Maryland, to define the current and projected use of utility coordination consultants. It provides statistics and quotes from the survey results to describe the rates of consultant use, typical work items, the qualifications for inclusion on approved consultant lists, beginning and end points for consultant work, the satisfaction of DOTs with the consultants' work, and other issues useful to DOT managers and utility coordination personnel.
Dynamics in Central European near‐natural Abies‐Fagus forests: Does the mosaic‐cycle approach provide an appropriate model?
Authors: Podlaski Rafat
Published: January 2008

Question: The mosaic‐cycle concept of forest dynamics dominates in Central Europe. According to this concept intermediate‐scale disturbances only accelerate the forest break‐up under existing cycles of forest development. Is such an approach correct, or should new developmental cycles be elaborated for intermediate‐scale disturbances?

Location: Near‐natural Abies alba ‐ Fagus sylvatica forests in the Świétokrzyski National Park in Central Poland. In these forests intermediate‐scale disturbances occurred between 1970 and 1990.

Methods: Data were collected twice in areas surrounding 212 permanent sample points (in 1994 and 2004). Two increment cores were taken from 259 sample Abies trees. The effect of intermediate‐scale disturbances on radial increment of Abies was assessed. Probabilities of stand transition during a 10‐year period between individual stages and phases of development of the mixed forest were calculated. The development stages and phases were arranged into hypothetical succession series of successive changes.

Results: In 1994 70 stands and in 2004, 47 stands representing stages and phases containing the older generation formed by trees > 100–150 years were found. Also, in 1994 142 and in 2004, 165 stands representing stages and phases containing the younger generations only, formed by trees < 100‐150 years, were recorded. Stages and phases containing only younger generations do not occur in the existing forest development cycle which does not consider the influence of intermediate‐scale disturbances separately. Two developmental cycles, which take into account the presence of the older generation and the younger generations only (under conditions of the occurrence of intermediate‐scale disturbances), are proposed.

Conclusion: The mosaic‐cycle concept of forest dynamics can be used to analyse the dynamics of Central European near‐natural mixed‐species forests, but new developmental cycles should be elaborated for intermediate‐scale disturbances.
Communication of positive newborn screening results for sickle cell disease and sickle cell trait: Variation across states
Authors: Kavanagh Patricia L. , Wang C. Jason , Therrell Bradford L. , Sprinz Philippa G. , Bauchner Howard
Published: January 2008

In the US, all states and the District of Columbia have universal newborn screening (NBS) programs for sickle cell disease (SCD), which also identify sickle cell trait (trait). In this project, we surveyed follow‐up coordinators, including one in the District of Columbia and two in Georgia, about protocols for stakeholder notification for SCD and trait. The primary outcomes were total number and type of stakeholder informed of a positive screen. We received 52 completed surveys (100% response). Primary care providers (PCPs) (100%), hematologists (81%), hospitals (73%), and families (40%) were the most commonly notified stakeholders of positive SCD screens, while PCPs (88%), hospitals (63%), and families (37%) were most commonly notified for trait. On average, 3.4 stakeholders were notified for a positive screening for SCD, compared to 2.4 stakeholders for sickle cell trait (P < 0.001). In multivariate analyses for SCD, we found a 2.9% increase in stakeholders notified for each additional year of universal screening mandated in a state (95% CI: 1.4–4.4%). For trait, we found an 8.5% increase in stakeholders notified for each additional follow‐up staff (95% CI: 1.3–15.7%), and a 1.3% increase for each additional percent of black births in the state (95% CI: 0.1–2.5%). Wide variation exists in stakeholder notification by NBS programs of positive screenings for SCD and trait. This variation may alter the effectiveness of NBS programs by location of birth. © 2008 Wiley‐Liss, Inc.
Patient advocacy in newborn screening: Continuities and discontinuities
Authors: Paul Diane B.
Published: January 2008

In the 1960s, patient advocacy groups were instrumental in efforts to mandate state testing of newborns for phenylketonuria (PKU), a recessively inherited disorder of phenylalanine metabolism. Advocacy groups have continued to actively lobby for the expansion of screening to other conditions detectable in newborns and, currently, for states' adoption of a uniform core screening panel. They have also been generally favorable to the offer of fee‐based supplemental screening services. In the early years of newborn screening, groups such as the National Association for Retarded Children (NARC) were strongly imbued with a public‐health ethic. This ethic has apparently eroded over time as the result of both broad social changes and the increasing entanglement of such groups with pharmaceutical and biotechnology companies. A history of newborn screening reveals both continuities and discontinuities in the agendas and funding of patient advocacy groups and in their rhetorical strategies. In particular, it demonstrates that there have always been tensions as well as partnerships with medical and other professionals, although the nature and intensity of the former have been affected by advocacy groups' increasing numbers, resources, and cultural authority. It also illuminates differences that have emerged as advocacy groups have informally allied with industry and adopted new rationales in support of access to testing. © 2008 Wiley‐Liss, Inc.
Nucleic Acid Biosensor for Detection of Human Immunodeficiency Virus Using Aquabis(1,10‐phenanthroline)copper(II) Perchlorate as Electrochemical Indicator
Authors: NIU Shu‐Yan , WANG Shao‐Juan , LI Xue‐Mei
Published: January 2008

The electrochemical behavior of aquabis(1,10‐phenanthroline)copper(II) perchlorate [Cu(H2O)(phen)2]·2ClO4, where phen=1,10‐phenanthroline, on binding to DNA at a glassy carbon electrode (GCE) and in solution, was described. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) results showed that [Cu(H2O)(phen)2]2+ had excellent electrochemical activity on the GCE with a couple of quasi‐reversible redox peaks. The interaction mode between [Cu(H2O)(phen)2]2+ and double‐strand DNA (dsDNA) was identified to be intercalative binding. An electrochemical DNA biosensor was developed with covalent immobilization of human immunodeficiency virus (HIV) probe for single‐strand DNA (ssDNA) on the modified GCE. Numerous factors affecting the probe immobilization, target hybridization, and indicator binding reactions were optimized to maximize the sensitivity and speed of the assay. With this approach, a sequence of the HIV could be quantified over the range from 7.8×10−9 to 3.1×10−7 mol·L−1 with a linear correlation of γ=0.9987 and a detection limit of 1.3×10−9 mol·L−1.
Synthesis and Mesomorphic Behavior of 3‐Alkyl‐2,5‐ bis[p‐(hexa‐2,4‐dienoyloxy)phenyl]‐Thiophene Derivatives
Authors: CHENG Xiao‐Hong , DONG Xing , ZHENG Tao , YE Hui , WEI Guang‐Hui
Published: January 2008

3‐Alkyl‐2,5‐bis[p‐(hexa‐2,4‐dienoyloxy)phenyl]‐thiophene derivatives were synthesized by using Kumada coupling and Suzuki coupling reactions as key steps. The thermotropic liquid crystalline behavior of these compounds was investigated by optical polarized microscopy, monotropic nematic mesophases were observed in such compounds.
Further New Cembrane Diterpenes from the Hainan Soft Coral Sarcophyton latum
Authors: YAN Xiao‐Hong , FENG Lin‐Yin , GUO Yue‐Wei
Published: January 2008

Two new cembranoid diterpenes, diepoxysarcophytonene (1) and sarconphytonol (2), were isolated from the Hainan soft coral Sarcophyton latum. Their structures including relative stereochemistry were established by 1D and 2D NMR spectroscopic techniques. Compound 1 showed weak inhibitory activity against COX‐2 in vitro at the concentration of 10−5 µmol·L−1 with the inhibitory rate of 55%.
Total Synthesis of 4′′‐O‐Acetylmananthoside B Part II: Synthesis of the Disaccharide Fragment
Authors: ZHAO Gui‐Long , YU Zhao‐Yun , LI Yan , PANG Li‐Na , WANG Jian‐Wu
Published: January 2008

A disaccharide compound, p‐methoxyphenyl 2,3,4‐tri‐O‐benzyl‐β‐L‐arabinopyranosyl‐(1→6)‐2‐O‐benzyl‐3,4‐di‐O‐acetyl‐β‐D‐galactopyranoside (17), was successfully synthesized from two monosaccharides L‐arabinose and D‐galactose and fully characterized. This compound can be used to build a natural product 4″‐O‐acetylmanan thoside B, which was isolated from the leaves and stems of a kind of Vietnamese Acanthaceae Justicia patentiflora.
Synthesis and Properties of N,N′‐Bis(difuroxano [3,4‐b:3′,4′‐d]phenyl)oxalic Amide
Authors: WANG Jian‐Long , LÜ Lian‐Ying , OU Yu‐Xian
Published: January 2008

N,N′‐Bis(difuroxano[3,4‐b:3′,4′‐d]phenyl)oxalic amide was synthesized via acylation, nitration, azidation, and pyrolysis‐denitrogenation from the starting materials of oxalyl chloride and 3,5‐dichloroaniline, under mild reaction conditions, with the yields of 81.0%, 82.0%, 86.0% and 81.7% respectively. The title compound and its precursors were characterized by 1H NMR, IR, MS, and elemental analysis. The title compound has a density of 1.92 g·cm−3 by a suspension method, a standard formation enthalpy of 979 kJ·mol−1 calculated by Gaussian programs, a detonation velocity of 8.17 km·s−1, and a detonation pressure of 31 GPa obtained by Kamlet Equation. The thermal decomposition reactions of the title compound at different heating rates were tested by differential scanning calorimetry (DSC). The kinetics parameters of the pyrolysis of the compound were calculated by Kissinger's method. The values of apparent activation energy (Ea) and pre‐exponential constant (A) were 226.7 kJ·mol−1 and 1023.17 s−1 respectively. It was presupposed that N,N′‐bis(difuroxano[3,4‐b:3′,4′‐d]phenyl)oxalic amide would be a promising high energetic explosive with low sensitivity.
Theoretical Studies on the One‐ and Two‐Photon Absorption Properties of Double‐bis(styryl)benzene Derivatives
Authors: HAN De‐Ming , FENG Ji‐Kang , REN Ai‐Min , SHANG Xiao‐Hong , ZHANG Xiang‐Biao , MA Yu‐Guang , HE Feng
Published: January 2008

Two series of bis(styryl)benzene derivatives (BSBD), namely the single‐BSBD and the double‐BSBD, were investigated. The equilibrium geometries and electronic structures were obtained by using the density functional theory B3LYP and 6‐31G basis set. In succession, the one‐ and two‐photon absorption properties of all the molecules were studied theoretically with a ZINDO‐SOS (sum‐over‐states) method in detail. It can be seen that the double‐BSBDs have larger two‐photon absorption (TPA) cross sections in the visible‐IR range than the corresponding single‐BSBDs, demonstrating that increasing the molecular dimension is a very effective method to enhance the values of the TPA cross sections. On the other hand, it can be also noticed that the values of the TPA cross sections are correlative with the ability of donating (accepting) electrons of the terminal substituent groups R [N(CH3)2, CH3, H and CF3] in these molecules. That is, the intramolecular charge transfer is also a factor for the enhancement of the TPA efficiency. To sum up, the idea of increasing the molecular dimension to enhance the TPA cross section value is a helpful direction to explore better TPA materials for practical applications. And the double‐BSBD molecules are promising TPA materials for the further investigation from the standpoint of the high transparency and the larger TPA cross sections.
Effect of the Carboxylate Salt on the CON Bond Homolysis of SG1‐Based Alkoxyamines
Authors: Bertin Denis , Gigmes Didier , Marque Sylvain R. A. , Siri Didier , Tordo Paul , Trappo Gregory
Published: January 2008

Alkoxyamines and persistent nitroxides are important regulators of the nitroxide mediated radical polymerization (NMP). Since the polymerization time decreases with increasing values of the homolysis rate constant (kd) for the CON bond between the polymer chain and the nitroxide moiety, the factors influencing kd are of considerable interest. Environmentally friendly polymerization methods, such as NMP in emulsion medium, have now been developed. The success of the polymerization depends not only on the strength of the CON bond but also on the solubility of the initiator/controller alkoxyamines, which control the nucleation. Various salts of SG1‐based alkoxyamines (S+−OOCCMeH‐SG1) labelled 1 a–f, where S+=Li+ (a), Na+ (b), K+ (c), nBu3HN+ (d), NH4+ (e), and nBu4N+ (f) are prepared, all of which are soluble in most organic solvents (e.g. pentane, dichlomethane, benzene, ethanol, etc.) as well as in water. Their kd values, which are measured in tert‐butylbenzene, reveal unexpected behaviors depending on the diastereoisomers. For the RR/SS diatereoisomers (i.e. slowly homolyzing isomers), kd was not found to be sensitive to any of the salts, whereas for the RS/SR diastereoisomers (i.e. quickly homolyzing isomers), kd is observed to decrease to a greater or lesser extent depending on the type of salt. The conformations of the diastereoisomers of several salts are determined by means of DFT calculations, and the orbital interactions are studied by natural bond orbital (NBO) analysis.
Monogenic migraine syndromes highlight novel drug targets
Authors: Gargus J. Jay , Shih Cindy H.
Published: January 2008

In the post‐genomic era, the paradigm for drug discovery has changed, as every gene may become a potential target. Genetic diseases provide a special window into gene target selection. This approach is being applied to migraine making use of the genes and mutations causing familial hemiplegic migraine (FHM). FHM is caused by missense mutations in CACNA1A, altering a neuronal P/Q Ca2+ channel, in ATP1A2, altering α2 Na,K‐ATPase, and in SCN1A, altering a neuronal sodium channel. These genes provide insights into migraine pathogenesis that likely extend to other forms of migraine as well. Since the three FHM genes are only co‐expressed in neurons, FHM is a neuronal, not a vascular, disease and because they all encode ion transport proteins, FHM is a neuronal channelopathy—meaning meta‐stable neuronal hyperexcitability is the substrate of migraine, much as it is for genetic epilepsy syndromes. This similarity is reinforced, since different mutations of all three FHM genes can produce seizure syndromes. This has implications for drug discovery in that seizure medications already known to modulate the FHM channel mechanisms warrant more targeted development, and that drugs targeted to vascular headaches, such as the historically effective triptans, or experimental botulinum toxin, may well work by similar nonvascular mechanisms. Finally, in model neurogenetic systems such as Caenorhabditis elegans, the FHM genes also provide both a comprehensive means to discover all genes involved in their signaling pathway—genes potentially involved in common forms of the disease, and an in vivo whole animal means to screen rapidly for novel therapeutics. Drug Dev Res 68:432–440, 2007. © 2008 Wiley‐Liss, Inc.
Evidence‐based medicine in migraine prophylactic treatment in childhood and adolescence
Authors: Balottin Umberto , Ferri Matteo , Termine Cristiano
Published: January 2008

Migraine is a common and disabling disorder, affecting children, adolescents, and adults. Prophylactic therapy should be considered when specific clinical conditions are fulfilled. Its goal is to reduce the frequency and duration of the attacks as well as the severity of pain, thus allowing patients to regain routine activities and ameliorating their quality of life. Using the principles of evidence‐based medicine, a review of available published data on the efficacy and safety of prophylactic treatments for migraine in children and adolescents is presented. Currently, only flunarizine and psychologically based interventions (e.g., relaxation training, biofeedback, and psychotherapeutic techniques) may be effective in migraine prophylaxis in children and adolescents. Owing to the paucity of evidence, there is a need for large, controlled, randomized, and masked trials. Clinical researchers should consider that migraine, especially in childhood and adolescence, is a complex condition, resulting from the interaction between biological, psychological, and environmental factors. Specific events, constitutional predisposition, individual and environmental‐emotional dynamics can play a significant role in the genesis and evolution of pain. Age‐related characteristics such as prevalence, diagnosis, quality of life, and therapy should be considered designing future studies. Drug Dev Res 68:461–468, 2007. © 2008 Wiley‐Liss, Inc.
Supramolecular Aggregates in Fluid Phases: Mesomorphic ortho‐Palladated Complexes with Substituted Crown Ethers and Their Potassium Adducts
Authors: Coco Silverio , Cordovilla Carlos , Espinet Pablo , Gallani Jean‐Louis , Guillon Daniel , Donnio Bertrand
Published: January 2008

New imines (HL) containing substituted dibenzo‐18‐crown‐6‐ethers and their dinuclear ortho‐palladated complexes, [Pd(μ‐X)L]2 (X– = CH3COO–, Cl–), have been prepared. The free imine ligands are not liquid crystals, but the palladium complexes, including acetato‐bridged derivatives, show liquid‐crystal properties. The mesomorphic palladium complexes bear six or eight alkoxy chains. Although a columnar arrangement of these chains might be expected, a smectic arrangement is in fact preferred for half of the metallomesogens prepared, which show a smectic C mesophase. Complexation with potassium produces a significant increase in the mesophase range and stability. Moreover, both the free imines and the corresponding liquid‐crystalline ortho‐palladated complexes form stable Langmuir films at the air–water interface.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
A Pair of Coordination Donor–Acceptor Ensembles for the Detection of Tartrate in Aqueous Media
Authors: Koo Chi‐Kin , Chow Cheuk‐Fai , Chiu Brenda Ka‐Wen , Lei Ngai‐Yu , Lam Michael Hon‐Wah , Wong Wai‐Yeung
Published: January 2008

A chemosensing approach utilizing a pair of heterodimetallic chemodosimetric ensembles of different analyte selectivity for the specific detection of targeted analytes in aqueousmedia was developed. Two new trinuclear, heterodimetallic donor–acceptor complexes, {Ru(tBubpy)(CN)4[Cu(cyclen)]2}(ClO4)2 ([Ru‐Cu]) and {Ru(tBubpy)(CN)4[Ni(cyclen)]2}(ClO4)2([Ru‐Ni]), where tBubpy = 4,4′‐di‐tert‐butyl‐2,2′‐bipyridine and cyclen = 1,4,7,10‐tetraazacyclododecane, have been synthesized and characterized. Their formation constants from K2[Ru(tBubpy)(CN)4] and [Cu(cyclen)](ClO4)2 and [Ni(cyclen)](ClO4)2 were measured to be 5.54 × 106 ([Ru‐Cu]) and 1.24 × 107 M–2 ([Ru‐Ni]), respectively, at 298 K. Luminescent chemodosimetric responses of these two ensembles towards various anionic analytes in neat aqueous buffer at pH 7.0 were evaluated. While each of these two ensembles showed relatively low analyte specificity, they can be used together to manifest a chemosensing XOR logic output for the specific detection of tartrate. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Synthesis and Structural Characterisation of cis‐ and trans‐[(hppH)2PtCl2], [(hppH)3­PtCl]+Cl– and Some New Salts of the [hppH2]+ Cation (hppH = 1,3,4,6,7,8‐Hexahydro‐2H‐pyrimido[1,2‐a]pyrimidine): The Importance of Hydrogen Bonding
Authors: Wild Ute , Roquette Pascal , Kaifer Elisabeth , Mautz Jürgen , Hübner Olaf , Wadepohl Hubert , Himmel Hans‐Jörg
Published: January 2008

The reaction between the guanidine derivative hppH (hppH = 1,3,4,6,7,8‐hexahydro‐2H‐pyrimido[1,2‐a]pyrimidine) and K2PtCl4 in H2O affords the salt [hppH2]2[PtCl4], which reacts further with Li(hpp) in thf to give cis‐[(hppH)2PtCl2]. The corresponding trans isomer is obtained from the reaction between [(dmso)2PtCl2] and hppH. hppH easily replaces another chlorido ligand to give [(hppH)3PtCl]+Cl–. [hppH2]Cl is formed as a hygroscopic side‐product in the synthesis of [(hppH)2PtCl2] and takes up 1 equiv. of H2O to give [hppH2]Cl·H2O. We report the crystal structures of cis‐ and trans‐[(hppH)2PtCl2], [(hppH)3PtCl]+Cl– and some salts of the [hppH2]+ cation, namely [hppH2]2[PtCl4] and the Pt‐free salts [hppH2][BPh4], [hppH2]Cl and [hppH2]Cl·H2O, which have an increasing degree of directed intermolecular hydrogen contacts. The crystal structure of [hppH2]Cl·H2O features helical chains of Cl–·H2O connected via [hppH2]+ cations. The effects of hydrogen bonding on the structures of these compounds in the solid state are discussed. Finally, quantum chemical calculations provide further insight into the structures and properties of some of these compounds. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Cobalt(III) Complexes of a Tripodal Ligand Containing Three Imidazole Groups: Properties and Structures of Racemic and Optically Active Species
Authors: Nakamura Hirofumi , Fujii Megumi , Sunatsuki Yukinari , Kojima Masaaki , Matsumoto Naohide
Published: January 2008

The complex [Co(H3L)](ClO4)3·H2O (1), where H3L {tris[2‐(4‐imidazoylmethylideneamino)ethyl]amine} is a tripodal ligand obtained by condensation of tris(2‐aminoethyl)amine and 4‐formylimidazole in a 1:3 molar ratio, was synthesized and optically resolved by fractional crystallization of the diastereomeric salt with [Sb2{(R,R)‐tart}2]2– [(R,R)‐tart = (2R,3R)‐tartrate(4–) ion]. From the less soluble part, Λ‐[Co(H2L)][Sb2{(R,R)‐tart}2]·4H2O (2) was isolated. Starting from 2, two optically active complexes, Λ‐[Co(H3L)](ClO4)3·1.5H2O (Λ‐1) and Λ‐[Co(L)] (Λ‐3), were obtained. The crystal structures of these complexes are compared with those of the racemic structures. Λ‐1 shows an unusually strong circular dichroism (λ = 488 nm, Δϵ = –7.74 M–1 cm–1) in the first d–d absorption band region. The effects of deprotonation–reprotonation of the uncoordinated imidazole NH groups of Λ‐[Co(H3L)]3+ on the UV/Vis and CD spectra and on the cyclic voltammograms were studied in methanol. Although the deprotonation–reprotonation reactions are reversible, the redox couple for the completely deprotonated species [CoIII/II(L)]0/– is not observed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Synthesis and Characterization of Cyclopropylpolyketides: A Combined Experimental and Theoretical Study
Authors: Rahn Thomas , Jiao Haijun , Baumann Wolfgang , Spannenberg Anke , Langer Peter
Published: January 2008

The first open‐chain cyclopropylpolyketides were prepared and characterized by experimental and computational methods. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Scaffolds based on hyaluronan crosslinked with a polyaminoacid: Novel candidates for tissue engineering application
Authors: Pitarresi G. , Palumbo F. S. , Cavallaro G. , Faré S. , Giammona G.
Published: January 2008

New porous scaffolds, with a suitable hydrolytic and enzymatic degradation, useful for tissue engineering applications have been obtained by a carbodiimide mediated reaction between hyaluronan (HA) and a synthetic polymer with a polyaminoacid structure such as α,β‐polyaspartylhydrazide (PAHy). Scaffolds with a different molar ratio between PAHy repeating units and HA repeating units have been prepared and characterized from a chemical and physicochemical point of view. Tests of indirect and direct cytotoxicity, cell adhesion, and spreading on these biomaterials have been performed by using murine L929 fibroblasts. The new biomaterials showed a good cell compatibility and ability to allow cell migration into the scaffolds as well as spreading on their surface. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
The kinetic and biological activity of different loaded rhBMP‐2 calcium phosphate cement implants in rats
Authors: Bodde Esther W. H. , Boerman Otto C. , Russel Frans G. M. , Mikos Antonios G. , Spauwen Paul H. M. , Jansen John A.
Published: January 2008

The healing of large bone defects can be improved by osteogenic bone graft substitutes, due to growth factor inclusion. A sustained release of these growth factors provides more efficient bioactivity when compared with burst release and might reduce the dose required for bone regeneration, which is desirable for socioeconomical and safety reasons. In this study, we compared different rhBMP‐2 loadings in a sustained release system of CaP cement and PLGA‐microparticles and were able to couple kinetic to biological activity data. Fifty‐two rats received a critical‐size cranial defect, which was left open or filled with the cement composites. The implants consisted of plain, high, and five‐fold lower dose rhBMP‐2 groups. Implantation time was 4 and 12 weeks. Longitudinal in vivo release was monitored by scintigraphic imaging of 131I‐labeled rhBMP‐2. Quantitative analysis of the scintigraphic images revealed a sustained release of 131I‐rhBMP‐2 for both doses, with different release profiles between the two loadings. However, around 70% of the initial dose was retained in both implant formulations. Although low amounts of rhBMP‐2 were released (2.4 ± 0.8 μg in 5 weeks), histology showed defect bridging in the high‐dose implants. Release out of the low‐dose implants was not sufficient to enhance bone formation. Implant degradation was limited in all formulations, but was mainly seen in the high‐dose group. Low amounts of sustained released rhBMP‐2 were sufficient to bridge critically sized defects. A substantial amount of rhBMP‐2 was retained in the implants because of the slow release rate and the limited degradation. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Interaction‐induced temperature‐dependent switching of the phase of commensurability oscillations in a one‐dimensional lateral superlattice
Authors: Mitzkus Christian , Wegscheider Werner , Umanski Vladimir , Eberl Karl , Weiss Dieter
Published: January 2008

We study magnetotransport of a two‐dimensional electron system (2DES) in the presence of an additional one‐dimensional potential modulation. The commensurability oscillations observed in such a density modulated 2DES show a temperature dependent switching of their phase in the case when the modulation pattern is orientated parallel to the current. This behavior is compared with a recent theory on the consequences of electron electron interaction by Gornyi and Mirlin [Phys. Rev. B 69, 45313, (2004)]. The theory predicts a temperature dependent mixing of the components of the resistivity tensor, which explains the phase switching as an overlapping of two kinds of commensurability oscillations. Good qualitative agreement between experiment and theory is found. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The quantum Hall effect in narrow quantum wires
Authors: Struck A. , Kawarabayashi T. , Zhuravlev A. , Ohtsuki T. , Kramer B. , Kettemann S.
Published: January 2008

The quantum phase diagram of disordered quantum wires in a strong magnetic field is reviewed. For uncorrelated disorder potential the 2‐terminal conductance, as calculated with the numerical transfer matrix method, shows zero temperature discontinuous transitions between exactly integer plateau values and zero. This is explained by the dimensional crossover of the bulk localisation length, which drives a transition from delocalised to localised edge states. In the thermodynamic limit, fixing the aspect ratio of the wire, there is a transition from the one dimensional chiral metal of extended edge states to localisation along the wire. In the vicinity of this chiral metal insulator transition (CMIT), states are identified which are superpositions of edge states with opposite chirality. The bulk contribution of such states is found to decrease with increasing wire width. Based on exact diagonalisation results for the eigenstates and their participation ratios, we conclude that these states are characteristic for the CMIT, and have the appearance of nonchiral edges states. Thereby these states are distinguishable from other states in the quantum Hall wire, namely, extended edge states, two‐dimensionally (2D) localized, quasi‐1D localized, and 2D critical states. In the presence of spatially correlated random potential we find with the numerical transfermatrix method that the potential correlation results in a shift of quantized conductance plateaus in long wires proportional to the strength of the random potential. This shift is found to be insensitive to the strength of magnetic fields and the same for all plateaus. A semiclassical explanation of this effect is proposed. We conclude with an outlook on modfications of the quantum phase diagram due to the spin degree of freedom of the electrons and their interactions. We discuss the stability of the phase diagram at finite temperature. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The effect of screening on current distribution and conductance quantisation in narrow quantum Hall systems
Authors: Gerhardts Rolf R.
Published: January 2008

We summarize and critically discuss the screening theory of the integer quantized Hall effect (IQHE), which was recently developed in order to understand scanning‐force‐microscope experiments on the current distribution in narrow Hall bars. The theory is based on the combination of a self‐consistent, non‐linear screening theory with a linear, local transport theory. In addition to the explanation of the mentioned experiments, it allows a simple understanding of the IQHE, including the enormous reproducibility of the measured quantized resistance values. Both achievements result from two key mechanisms: The first, which follows from the screening theory, is the existence of incompressible strips, with integer values of the local Landau level filling factor and quantized values of longitudinal and Hall resistivity, in certain magnetic field intervals. The second, a result of the local transport theory, is the confinement of an imposed dissipative current to these strips. This confinement leads to the quantization of the global resistances, without any localization assumptions. We also discuss limitations and possible extensions as well as further applications of this theory. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Phonon and transport measurements in the fractional quantum Hall effect
Authors: Schulze‐Wischeler Fritz , Dethlefsen Annelene F. , Hohls Frank , Zeitler Uli , Haug Rolf J.
Published: January 2008

The properties of a fractional quantum Hall system has been investigated with phonon experiments and with transport experiments. A detailed description of the phonon absorption technique is given. We measure the relative specific heat in the fractional quantum Hall effect regime at various filling factors. We use phonons to measure the activation gap Δ of the fractional quantum Hall states at constant fillings as a function of the perpendicular magnetic field B. At a given filling factor nearly all gaps measured show a square‐root dependence on the magnetic field and can be described by one single fit parameter related to the composite fermion effective mass. In addition, we present transport experiments to deduce energy gaps. Here, an astonish linear dependence of Δ on B is observed for a number of fractional filling factors. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Sharp quantum Hall edges: Experimental realizations of edge states without incompressible strips
Authors: Grayson Matthew , Steinke Lucia , Huber Michael , Schuh Dieter , Bichler Max , Abstreiter Gerhard
Published: January 2008

Experimental results of sharp edge potentials in the quantum Hall (QH) regime of a two‐dimensional electron system are presented. First the general QH edge state picture is reviewed, including recent theory which explains the importance of incompressible strips at the sample edge. Then two sharp edge geometries are presented where incompressible strips are predicted to vanish below the scale of the magnetic length: T ‐junction edge tunneling devices and L ‐junction bent quantum wells. Tunnel spectroscopy in the T ‐junction device directly measures the real space position of the edge state orbit centers, verifying an almost ideal sharp edge confinement and providing evidence that incompressible strips vanish in such a potential. Conduction along the junction of the L ‐sample is presented, revealing unconventional temperature and voltage dependence along a unique type of QH boundary. Hartree calculations explain how this behavior can result from the sharp non‐planar confinement potential which is not possible to realize either in planar systems or at soft‐confinement boundaries. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Review of Literature‐Based Quantitative Structure–Activity Relationship Models for Bioconcentration
Authors: Pavan Manuela , Netzeva Tatiana I. , Worth Andrew P.
Published: January 2008

This paper reviews the state of the art of in silico methods for assessing the tendency of a substance to bioconcentrate in aquatic organisms usually expressed as its Bioconcentration Factor (BCF). It is based on an in‐depth review performed by the European Chemicals Bureau of the European Commission's Joint Research Centre in support of the development of technical guidance for the implementation of the REACH legislation, and is one of a series of minireviews in this journal. The most widely used in silico approaches to estimate BCF are described, with emphasis on literature‐based (Quantitative) Structure‐Activity Relationship [(Q)SAR] models: (1) linear relationships that correlate the BCF with octanol–water partition coefficient; (2) (Q)SAR models based on experimentally derived descriptors and (3) new (Q)SAR models aimed to evaluate the potential of other descriptors. Recommendations for further research are also provided.
(Q)SARs for Predicting Effects Relating to Reproductive Toxicity
Authors: Cronin Mark T. D. , Worth Andrew P.
Published: January 2008

This paper reviews the current status of structure‐based methods for predicting adverse reproductive effects in mammals. The methods described include (Quantitative) Structure–Activity Relationships ((Q)SARs), expert systems and the less formalised approaches of read‐across within (chemical) categories. There are a number of problems with applying QSARs to reproductive toxicology notably the complexity, subtlety and sometimes ill‐defined nature of the endpoints and lack of data available for modelling. A small number of ((Q)SARs have been developed for individual classes of compounds for well‐defined effects. These are supplemented by expert systems approaches of all types [e.g. DEREK for Windows, TOPKAT, MC4PC, PASS, Organisation for Economic Co‐operation and Development (OECD) QSAR Application Toolbox] for a variety of endpoints associated with reproductive toxicology. By far the largest, and best developed, group of models are those for receptor binding effects related to endocrine disruption, in particular to the Oestrogen Receptor (ER) and, to a lesser extent, the Androgen Receptor (AR). Strategies to improve predictive capabilities for reproductive toxicology are suggested.