bluuebunny/crossref_metadata_2025 huggingface dataset:
Rehabilitation Biomechanics
Authors: Koontz Alicia M. , McCrory Jean L. , Cham Rakié , Yang Yusheng , Wilkinson Matthew
Published: April 2006

Rehabilitation biomechanics is a field of study that addresses the impact of disability and the effectiveness of rehabilitation therapies and interventions on human performance. Engineering and physics principles are applied to evaluate and analyze body movement and manipulation. This article describes biomechanical evaluation as a clinical and research tool for assessing the effect of disability on task performance, evaluating the risk of injury, and optimizing the fit of an assistive device to an individual. Methods and tools for measuring human kinematics, kinetics, energy expenditure, and muscle activity in rehabilitation applications are presented in addition to the use of biomechanical models and computer simulation as tools to determine parameters that cannot be measured with current technology or are difficult to measure directly. An introduction to gait analysis is reviewed with specific examples of cases where biomechanical analyses have led to new knowledge and improvements in clinical practices. Lastly, future trends and needs in rehabilitation biomechanics applications and research are discussed in relation to the increasing age of the population and persons aging with a disability.
Phase Unwrapping
Authors: Ying Leslie
Published: April 2006

Phase unwrapping is the reconstruction of the original true phase of a wave from its modulo 2πvalues. It originates in a variety of applications, such as synthetic aperture radar, magnetic resonance imaging, and adaptive optics. In this article, the problem of two‐dimensional phase unwrapping is defined and the challenges are addressed. A variety of established approaches to the problems are reviewed and compared, and their advantages and disadvantages are discussed. Among the many phase unwrapping applications, the article focussed on magnetic resonance imaging and explains how phase unwrapping is used in field mapping, inversion recovery, and flow imaging.
Heart Rate Variability (HRV): Sleep Disordered Breathing
Authors: Nazeran Homer , Pamula Yvonne , Behbehani Khosrow
Published: April 2006

Sleep‐related breathing disorders are a common but often underdiagnosed condition both in adults and in children. It is now evident that abnormal ventilation during sleep can cause a range of adverse physiological sequela including autonomic dysfunction. Extensive research effort over the past two decades has demonstrated that patterns of cyclic variation in the heart rate (HR) or heart rate variability (HRV) are closely linked to partial reduction or complete cessation of airflow during abnormal breathing events (hypopnea or apnea) during sleep. These efforts culminated in the year 2000, when Thomas Penzel from the Hospital of Phillips‐University in Germany and George Moody from MIT, with their collaborators, coordinated a global competition to stimulate rapid research advances in deploying the HRV signal to detect sleep apnea (Computers in Cardiology Apnea Challenge, 2000).

The outcome of these efforts have motivated a number of prominent international research groups to use advanced signal processing methods to analyze the HRV signal and to develop dedicated instrumentation or software packages with the objective to detect sleep disordered breathing in symptomatic subjects at an early stage. A comprehensive review of the literature in this field reveals the value, reliability, sensitivity, specificity, and limitations of these methods and devices. Even though the ultimate goal of simplified diagnosis of sleep disordered breathing from HRV signal analysis is not fully realized yet, it is clearly established that the HRV signal carries a wealth of measures that are sensitive to sleep stages, sleep disordered breathing (SDB), and other disorders influencing the cardiovascular system. Thus, careful analysis of the readily accessible electrocardiogram (ECG) and its derived HRV signal, along with new and sophisticated nonlinear signal analysis methods provide the exciting promise that accurate separation of sleep stages and reliable detection of SDB as well as other disorders influencing the autonomic control of the heart is within reach.

In this chapter, we first present a simplified and distilled overview of regulation of the HR by the autonomic nervous system (ANS), sleep physiology, and pathophysiology in children and adults. This is followed by a brief review of the HRV signal derivation and processing methods applicable to its analysis for detection of SDB. We conclude the chapter with an example graphical user interface and consider some issues associated with development of integrated software packages to facilitate the simplified detection of SDB from HRV signals.
Gait Retraining After Neurological Disorders
Authors: Lünenburger Lars , Lam Tania , Riener Robert , Colombo Gery
Published: April 2006

Neurological disorders like traumatic brain injury, stroke, and spinal cord injury often adversely affect a person's ability to walk. Restoration of gait function is an important goal in the rehabilitation of these patients. Appropriate motor training can facilitate adaptations in the nervous system to recover function after an injury. Important aspects of motor training include task‐specific performance and repetition of the affected movement. This means that to improve walking, the patient must walk. Body‐weight supported treadmill training is becoming increasingly accepted as a valuable strategy for gait rehabilitation after neurological injury. Treadmills that run at slow locomotor speeds allow patients who are partially unloaded from their body weight to walk, possibly with manual assistance by one or more therapists. However, manual therapy is limited in terms of duration, repeatability, and quantification. Robotic devices allow longer training sessions with better support and control of the leg movements. Current developments are directed to patient‐cooperative strategies, which allow the robotic device to adapt to the patient's needs and efforts. Furthermore, proper design of these devices leaves open many possibilities for a repertoire of additional assessment tools that measure patients’ performance during training and other clinical parameters. Future directions in this field include combining robotic devices with functional electrical stimulation and the development of robotic orthoses for retraining overground walking.
Hybrid Solar Cells from Regioregular Polythiophene and ZnO Nanoparticles
Authors: Beek W. J. E. , Wienk M. M. , Janssen R. A. J.
Published: April 2006

Blends of nanocrystalline zinc oxide nanoparticles (nc‐ZnO) and regioregular poly(3‐hexylthiophene) (P3HT) processed from solution have been used to construct hybrid polymer–metal oxide bulk‐heterojunction solar cells. Thermal annealing of the spin‐cast films significantly improves the solar‐energy conversion efficiency of these hybrid solar cells to ∼ 0.9 %. Photoluminescence and photoinduced absorption spectroscopy demonstrate that charge‐carrier generation is not quantitative, because a fraction of P3HT appears not to be in contact with or in close proximity to ZnO. The coarse morphology of the films, also identified by tapping‐mode atomic force microscopy, likely limits the device performance.
Structure and Electrical Properties of Ni Nanowire/Multiwalled‐Carbon Nanotube/Amorphous Carbon Nanotube Heterojunctions
Authors: Luo J. , Xing Y. J. , Zhu J. , Yu D. P. , Zhao Y. G. , Zhang L. , Fang H. , Huang Z. P. , Xu J.
Published: April 2006

A one‐dimensional heterojunction is fabricated and characterized. This heterojunction comprises a Ni nanowire, a multiwalled carbon nanotube (MWCNT), and an amorphous carbon nanotube (a‐CNT). The three components are in an end‐to‐end configuration, and form two MWCNT contacts, namely a Ni/MWCNT and an MWCNT/a‐CNT contact. The interfacial structures of the two contacts show that multiple outer walls in the MWCNT simultaneously contact the Ni nanowire and the a‐CNT, and can simultaneously participate in electrical transport. By investigating the electrical‐transport properties of the heterojunctions, the two contacts to the MWCNT in every heterojunction are found to behave as two diodes connected in series face‐to‐face, at least one of which exhibits the characteristics of a nearly ideal Schottky diode and obeys thermionic‐emission theory, wherein only the image force lowers the Schottky barrier. The appearance of this type of nearly ideal diode is attributed to the good contacts to the multiple outer walls of the MWCNTs realized by the heterojunctions' structures.
Molecular Materials by Self‐Assembly of Porphyrins, Phthalocyanines, and Perylenes
Authors: Elemans J. A. A. W. , van Hameren R. , Nolte R. J. M. , Rowan A. E.
Published: April 2006

Porphyrins, phthalocyanines, and perylenes are compounds with great potential for serving as components of molecular materials that possess unique electronic, magnetic and photophysical properties. In general, a highly specific communication between a large number of these chromophores is required in order to express their function to a maximal level, and for this reason it is of importance to construct arrays in which the molecules are organized in well‐defined geometries with respect to their neighbors. This review is an account of some recent efforts to construct highly ordered assemblies of porphyrins, phthalocyanines, and perylenes by means of self‐assembly in solution and on surfaces, and by attaching them to polymeric scaffolds.
Approximate dynamic programming: Application to process supply chain management
Authors: Choi Jaein , Realff Matthew J. , Lee Jay H.
Published: April 2006

Many continuous process industries are required to operate multiproduct supply chains under significant uncertainty in market demands and prices, and mathematical programming formulations have been developed for the deterministic version of the problem. However, available extensions to the stochastic case cannot be readily used to obtain an optimal operating policy in practice because the uncertainty results in an explosion of the scenarios to be considered over an extended time horizon. In this article we represent the uncertainty through Markov chains and use an approach based on stochastic dynamic programming (DP), which can generate a dynamic operating policy that incorporates information about the uncertainty in the problem at each time step. DP is computationally infeasible because of the size of the state and action space for realistic problems. We propose a novel stochastic optimization algorithmic framework called “DP in a heuristically restricted state space.” The confined state space is generated by simulating various potential scenarios under centralized dynamic inventory and production policy generated by combining static local inventory policy heuristics. The resulting DP policy responds to the time‐varying demand for products by appropriately stitching together decisions made by the local static policies. This is a new formulation for effectively combining heuristic policies. © 2006 American Institute of Chemical Engineers AIChE J, 2006
Uncertainty analysis on the righthand side for MILP problems
Authors: Jia Zhenya , Ierapetritou Marianthi G.
Published: April 2006

A systematic framework is developed to solve the parametric mixed integer linear programming (pMILP) problems where uncertain parameters are present on the righthand side (RHS) of the constraints. For the case of multiple uncertain parameters, a new algorithm of multiparametric linear programming (mpLP) is proposed, which solves a number of nonlinear problems (NLP) iteratively. At each iteration, a point at which the objective value cannot be represented by the current optimal functions is found, and the new optimal function is included in the next iteration. Given the range of uncertain parameters in a MILP problem, the output of this proposed framework is a set of optimal integer solutions and their corresponding critical regions and optimal functions. A number of examples are presented to illustrate the applicabilities of the proposed approach and comparison with existing techniques. © 2006 American Institute of Chemical Engineers AIChE J, 2006
In vivo activation of SMN in spinal muscular atrophy carriers and patients treated with valproate
Authors: Brichta Lars , Holker Irmgard , Haug Karsten , Klockgether Thomas , Wirth Brunhilde
Published: April 2006

Objective

Spinal muscular atrophy results from loss of the survival motor neuron 1 (SMN1) gene and malfunction of the remaining SMN2. We investigated whether valproic acid can elevate human SMN expression in vivo.

Methods

Blood was collected from 10 spinal muscular atrophy carriers and 20 spinal muscular atrophy patients treated with valproic acid.

Results

Seven of 10 carriers demonstrated increased SMN messenger RNA and protein levels. SMN2 messenger RNA levels were elevated in 7 patients and unchanged or decreased in 13 patients.

Interpretation

We provide first proof of the in vivo activation of a causative gene by valproic acid in an inherited disease and discuss strategies of monitoring drug response in patients.
Embryotoxicity of oral administered chlorothalonil in mice
Authors: Farag Amina T. , Karkour Tarek Abdel‐Zaher , Okazy Ahmed El
Published: April 2006

BACKGROUND: Chlorothalonil (2,4,5,6‐tetrachloroisophthalonitril), the nephrotoxic fungicide, was examined for its potential to produce developmental toxicity in mice after oral administration. METHODS: Pregnant ICR (CD‐1) mice were given sublethal doses of 0 (corn oil), 100, 400, and 600 mg/kg/day chlorothalonil by gavage on gestation days (GD) 6–15. RESULTS: Maternal effects in 400 and 600 mg/kg/day dose groups included signs of toxicity such as weakness and depression in the maternal activity, and reduction in body weight and weight gain. No maternal toxicity was apparent in the 100 mg/kg/day dose group. Maternal exposure to chlorothalonil during organogenesis significantly affected the number of live fetuses, early resorption, and mean fetal weight in the 400 and 600 mg/kg/day dose groups. No external, visceral, and skeletal abnormalities were observed among any of the treated groups compared to the control. CONCLUSIONS: On the basis of the present results chlorothalonil can produce clinical signs of toxicity and fetotoxicity without teratogenic effects at 400 and 600 mg/kg/day dose groups. Birth Defects Research (Part B) 77:104–109, 2006. © 2006 Wiley‐Liss, Inc.
The influence of continuous exposure to 50 Hz electric field on nerve regeneration in a rat peroneal nerve crush injury model
Authors: Aydin Mustafa Asim , Comlekci Selcuk , Ozguner Meltem , Cesur Gokhan , Nasir Serdar , Aydin Zeynep Dilek
Published: April 2006

The effect of power frequency electric field (EF) on nerve regeneration was investigated on a rat peroneal nerve crush injury model. The animals were assigned to three groups: 50 Hz EF and Static EF groups were exposed at 10 kV/m. The sham group was kept in the same setting without any EF applications. EF was uninterruptedly applied for 21 days postoperatively. Repeated measures analysis of daily walking tracks during EF exposure demonstrated lower toe spread recovery (TSR) in the 50 Hz EF group. Significant difference across the groups was found only at days 7, 8, 12, 16, 17, 20, and 21 when TSR was analyzed for each measurement time. Print length recovery and peroneal function index did not differ across the groups. Walking track parameters were found to recover to their baseline values by day 28 in all groups. Day 14 but not day 21 measurements revealed smaller nerve cross‐sectional area, lower total regenerating axon area, and higher mean myelin debris area in 50 Hz EF group. Both day 14 and 21 measurements revealed higher total myelin debris area, lower EDL muscle weight, and lack of significant enlargement in nerve cross‐section distal to the injury, compared to the normal counterpart in 50 Hz EF group. All differences were in keeping with lower rates of Wallerian degeneration and nerve regeneration in 50 Hz EF group. When walking track, histomorphometry and muscle weight are considered individually, their differences across the groups may appear to be subtle to derive a conclusion for a 50 Hz EF effect. However, their concordance with each other in direction of effect suggests that continuous 50 Hz EF exposure has a weak effect that is detrimental mostly to the rate of early nerve regeneration in this axonotmetic injury model. Recovery of walking tracks was not different between Static EF and Sham groups. This suggests that the surface charges that may indirectly affect walking behaviors of the rats, do not account for the lower recovery of TSR in 50 Hz EF group. Differences in nerve regeneration between 50 Hz EF and Static EF groups suggests that electric induction may be required for pure EF effects even though the estimated density of induced fields is not above the endogenous background level for the 50 Hz EF exposure in this study. Bioelectromagnetics 27:401–413, 2006. © 2006 Wiley‐Liss, Inc.
Exposure to AC and DC magnetic fields induces changes in 5‐HT1B receptor binding parameters in rat brain membranes
Authors: Espinosa José Manuel , Liberti Micaela , Lagroye Isabelle , Veyret Bernard
Published: April 2006

The binding properties of the G‐protein coupled receptor (GPCR) serotonin 5‐HT1B receptor were studied under exposure to AC (50 and 400 Hz) and DC magnetic fields (MF) in rat brain membranes. This was an attempt at replicating the positive findings of Massot et al. In saturation experiments using [3H]5‐HT, 1‐h exposures at 1.1 mTrms 50 Hz caused statistically significant increases in both the KD and Bmax binding parameters, from 1.74 ± 0.3 to 4.51 ± 0.86 nM and from 1428 ± 205 to 2137 ± 399 CPM, respectively, in good agreement with previous results. Exposure of the membranes at 400 Hz 0.675 mTrms did not elicit a larger increase in KD in spite of a much larger induced current density. DC fields (1.1 and 11 mT) had a lesser effect compared to AC fields at low values of KDsham, but decreased the affinity at higher values of KDsham. Modeling of the receptor‐ligand‐G protein interactions using the extended ternary complex model yielded good fits for all our data and that of Massot et al., showing that the AC field may act by decreasing the ability of the G‐protein to alter the ligand‐receptor affinity. The hypothesis is that the bipolar nature of the AC field explains the different nature of the effects observed with AC and DC exposures. These findings constitute one of the few documented pieces of evidence for cell‐free effects of DC and extremely low frequency (ELF) AC MFs in the mT range. Bioelectromagnetics 27:414–422, 2006. © 2006 Wiley‐Liss, Inc.
Transient performance of two‐phase partitioning bioreactors treating a toluene contaminated gas stream
Authors: Boudreau Neal G. , Daugulis Andrew J.
Published: April 2006

Two‐phase partitioning bioreactors (TPPBs) consist of a cell‐containing aqueous phase and an immiscible organic phase that sequesters and delivers toxic substrates to cells based on equilibrium partitioning. The immiscible organic phase, which acts as a buffer for inhibitory substrate loadings, makes it possible for TPPBs to handle high volatile organic compound (VOC) loadings, and in this study the performance of liquid n‐hexadecane and solid styrene butadiene (SB) polymer beads used as partitioning phases were compared to a single aqueous phase system while treating transient loadings of a toluene contaminated air stream by Achromobacter xylosoxidans Y234. The TPPBs operated as well‐mixed stirred tanks, with total working volumes of 3 L (3 L aqueous for the single‐phase system, 2 L aqueous and 1 L n‐hexadecane for the solvent system, and 2.518 L aqueous volume and 500 g of SB beads for the polymer system). Two 60‐min step changes (7 and 17 times the nominal loading rates, termed “small” and “large” steps, respectively) were imposed on the systems and the performance was characterized by the overall removal efficiencies, instantaneous removal efficiency recovery times (above 95% removal), and dissolved oxygen recovery times. For the small steps, with a nominal loading of 343 g/m3/h increasing to 2,400 g/m3/h, the TPPB system using n‐hexadecane as the second phase performed best, removing 97% of the toluene fed to the system compared with 90% for the polymer beads system and only 69% for the single‐phase system. The imposed large transient gave similar results, although the impact of the presence of a second sequestering phase was more pronounced, with the n‐hexadecane system maintaining much reduced aqueous toluene concentrations leading to significantly improved performance. This investigation also showed that the presence of both n‐hexadecane and SB beads improved the oxygen transfer within the systems. © 2006 Wiley Periodicals, Inc.
Isolation and analysis of a baculovirus vector that supports recombinant glycoprotein sialylation by SfSWT‐1 cells cultured in serum‐free medium
Authors: Hill Daniel R. , Aumiller Jared J. , Shi Xianzong , Jarvis Donald L.
Published: April 2006

The inability to sialylate recombinant glycoproteins is a critical limitation of the baculovirus‐insect cell expression system. This limitation is due, at least in part, to the absence of detectable sialyltransferase activities and CMP‐sialic acids in the insect cell lines routinely used as hosts in this system. SfSWT‐1 is a transgenic insect cell line encoding five mammalian glycosyltransferases, including sialyltransferases, which can contribute to sialylation of recombinant glycoproteins expressed by baculovirus vectors. However, sialylation of recombinant glycoproteins requires culturing SfSWT‐1 cells in the presence of fetal bovine serum or another exogenous source of sialic acid. To eliminate this requirement and extend the utility of SfSWT‐1 cells, we have isolated a new baculovirus vector, AcSWT‐7B, designed to express two mammalian enzymes that can convertN‐acetylmannosamine to CMP‐sialic acid during the early phase of infection. AcSWT‐7B was also designed to express a model recombinant glycoprotein during the very late phase of infection. Characterization of this new baculovirus vector showed that it induced high levels of intracellular CMP‐sialic acid and sialylation of the recombinantN‐glycoprotein upon infection of SfSWT‐1 cells cultured in serum‐free medium supplemented withN‐acetylmannosamine. In addition, co‐infection of SfSWT‐1 cells with AcSWT‐7B plus a conventional baculovirus vector encoding human tissue plasminogen activator resulted in sialylation of this recombinantN‐glycoprotein under the same culture conditions. These results demonstrate that AcSWT‐7B can be used in two different ways to support recombinantN‐glycoprotein sialylation by SfSWT‐1 cells in serum‐free medium. Thus, AcSWT‐7B can be used to extend the utility of this previously described transgenic insect cell line for recombinant sialoglycoprotein production. © 2006 Wiley Periodicals, Inc.
Assembly of Nanotubes of Poly(4‐vinylpyridine) and Poly(acrylic acid) through Hydrogen Bonding
Authors: Tian Ying , He Qiang , Cui Yue , Tao Cheng , Li Junbai
Published: April 2006

Nanotubes of poly(4‐vinylpyridine) (PVP) and poly(acrylic acid) (PAA) were fabricated by hydrogen bonding based on layer‐by‐layer (LbL) assembly. The uniform and flexible tubular structures were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). FTIR and X‐ray photoelectron spectroscopy (XPS) measurements confirm the formation of hydrogen bonds in the assembled nanotubes. PAA can be released from the assembled PAA/PVP nanotubes in a basic aqueous solution to give the walls of the tubes a porous structure. Such assembled nanotubes can be considered as carriers for catalysts or drugs, especially in aqueous solution against capillary force.
The clinical impact of histopathologic response assessment by residual tumor cell quantification in esophageal squamous cell carcinomas
Authors: Brücher Björn L. D. M. , Becker Karen , Lordick Florian , Fink Ulrich , Sarbia Mario , Stein Hubert , Busch Raymonde , Zimmermann Frank , Molls Michael , Höfler Heinz , Siewert Jörg R.
Published: April 2006

BACKGROUND

The objectives of this study were to investigate histomorphologic features as a response classification after neoadjuvant radiochemotherapy (RTx/CTx) and to correlate the results with clinical outcome parameters (e.g., postoperative morbidity and mortality, recurrence, and survival) in patients with locally advanced esophageal squamous cell carcinoma (ESCC).

METHODS

Three hundred eleven patients with histologically proven, locally advanced, intrathoracic ESCC (clinical T3 or T4, N0‐N+, M0) located at or above the level of the tracheal bifurcation underwent preoperative, combined, simultaneous RTx/CTx followed by esophagectomy. Response to RTx/CTx was classified by the quantification of residual tumor cells. A histopathologic response was defined as <10% residual tumor cells found within the specimen compared with a histopathologic nonresponse, which was characterized by >10% residual tumor cells.

RESULTS

A histopathologic response was correlated significantly with complete tumor resection status (R0 resection) (P .0001), histopathologic tumor (ypT) category (P <.0001), lymph node involvement (P <.0001), lymphatic vessel invasion (P <.001), and survival (P <.0001). A multivariate Cox regression analysis revealed that histopathologic response classification according to the percentage of residual tumor cells was an independent prognostic factor (P <.0001). Nonresponders had greater postoperative pulmonary morbidity (P = .01), a greater 30‐day mortality rate (P = .02), and a dismal survival rate compared to histopathologic responders (P <.0001).

CONCLUSIONS

Histopathologic response evaluation based on the quantification of residual tumor cells provided meaningful information for the assessment of outcomes among patients with ESCC who have underwent neoadjuvant RTx/CTx. The current results indicated that histopathologic responders may represent a subgroup of patients who benefit from neoadjuvant therapy followed by surgery. Cancer 2006. © 2006 American Cancer Society.
Prognostic significance of Wilms tumor gene (WT1) mRNA expression in soft tissue sarcoma
Authors: Sotobori Tsukasa , Ueda Takafumi , Oji Yusuke , Naka Norifumi , Araki Nobuhito , Myoui Akira , Sugiyama Haruo , Yoshikawa Hideki
Published: April 2006

BACKGROUND

There have been several recent reports that Wilms tumor gene (WT1) mRNA is overexpressed in many types of neoplasms, and those results suggested that WT1 has oncogenic properties. The objective of the current study was to evaluate the prognostic significance of WT1 mRNA expression in patients with soft tissue sarcoma.

METHODS

Levels of WT1 mRNA expression were examined by quantitative, real‐time reverse transcriptase‐polymerase chain reaction analysis in frozen tissue samples from 52 patients with soft tissue sarcoma. Various clinicopathologic factors were analyzed along with the disease‐specific survival rate for correlations with WT1 mRNA expression levels.

RESULTS

The levels of WT1 mRNA expression in a variety of soft tissue sarcomas were significantly greater compared with the levels in normal soft tissue samples (P = .0212). No significant correlation was observed between the level of WT1 mRNA expression and clinicopathologic factors, including gender, age, primary tumor site, tumor depth, tumor size, histologic grade, and distant metastasis at initial presentation. The disease‐specific survival rate for patients with high WT1 mRNA expression levels was found significantly poorer compared with the rate for patients with low WT1 mRNA expression levels (P = .0182). Moreover, multivariate analysis indicated that a high WT1 mRNA expression level was an independent, adverse prognostic factor for disease‐specific survival (hazards ratio, 2.6; P = .0488).

CONCLUSIONS

WT1 mRNA expression level can serve as a potent prognostic indicator in soft tissue sarcoma patients. Cancer 2006. © 2006 American Cancer Society.
Adoption of voluntary environmental tools for sustainable tourism: analysing the experience of Spanish hotels
Authors: Ayuso Silvia
Published: April 2006

Since the early 1990s, tourism companies, mostly hotel facilities, have undertaken different voluntary initiatives to show their commitment to sustainable tourism. Among the voluntary tools applied by the hotel industry, the most common are codes of conduct, best environmental practices, eco‐labels, environmental management systems (EMSs) and environmental performance indicators.

This article presents the findings of empirical research conducted with Spanish hotels that have adopted one or more of the existing environmental tools. Based on a qualitative exploration of perceptions and experiences of hotel managers applying these instruments, the general understanding of the concept of sustainable tourism is examined, and the practical application of different voluntary environmental instruments is analysed. In an attempt to interpret the facilitators and barriers reported by hotel companies, three interpretative approaches are combined to explain the selective adoption of environmental tools: the perspective of competitive advantages, the perspective of stakeholders' influence and the perspective of the human cognitive process. Copyright © 2006 John Wiley & Sons, Ltd and ERP Environment.
A novel search method to reduce PAPR of an OFDM signal using partial transmit sequences
Authors: Tu Hao‐Chung , Chiu Chien‐Ching
Published: April 2006

One of the main drawbacks of orthogonal frequency division multiplexing (OFDM) is the high peak‐to‐average power ratio (PAPR) of the transmitted OFDM signal. Partial transmit sequence (PTS) technique can improve the PAPR statistics of an OFDM signal. As ordinary PTS technique requires an exhaustive search over all combinations of allowed phase factors, the search complexity increases exponentially with the number of sub‐blocks. In this paper, we propose a novel PTS technique with reduced complexity that each level inverts twice of phase factor bits from previous level. Then we also use initial random phase sequence to find the better search way of PAPR reduction. Numerical results show that the proposed method can achieve significant reduction in search complexity with little performance degradation. Copyright © 2006 John Wiley & Sons, Ltd.
fused‐somites–like mutants exhibit defects in trunk vessel patterning
Authors: Shaw Kenna M. , Castranova Daniel A. , Pham Van N. , Kamei Makoto , Kidd Kameha R. , Lo Brigid D. , Torres‐Vasquez Jesus , Ruby Alexander , Weinstein Brant M.
Published: April 2006

We identified four mutants in two distinct loci exhibiting similar trunk vascular patterning defects in an F3 genetic screen for zebrafish vascular mutants. Initial vasculogenesis is not affected in these mutants, with proper specification and differentiation of endothelial cells. However, all four display severe defects in the growth and patterning of angiogenic vessels in the trunk, with ectopic branching and disoriented migration of intersegmental vessels. The four mutants are allelic to previously characterized mutants at the fused‐somites (fss) and beamter (bea) loci, and they exhibit comparable defects in trunk somite boundary formation. The fss locus has been shown to correspond to tbx24; we show here that bea mutants are defective in the zebrafish dlC gene. Somitic expression of known vascular guidance factors efnb2a, sema3a1, and sema3a2 is aberrantly patterned in fss and bea mutants, suggesting that the vascular phenotype is due to loss of proper guidance cues provided by these factors. Developmental Dynamics 235:1753–1760, 2006. Published 2006 Wiley‐Liss, Inc.
Differential role of 14‐3‐3 family members in Xenopus development
Authors: Lau Jeffrey M.C. , Wu Chunlai , Muslin Anthony J.
Published: April 2006

The 14‐3‐3 proteins are intracellular dimeric phosphoserine/threonine binding molecules that participate in signal transduction, checkpoint control, nutrient sensing, and cell survival pathways. Previous work established that 14‐3‐3 proteins are required in early Xenopus laevis development by modulating fibroblast growth factor signaling. Although this general requirement for 14‐3‐3 proteins in Xenopus early embryogenesis is established, there is no information about the specific role of individual 14‐3‐3 genes. Botanical studies previously demonstrated functional specificity among 14‐3‐3 genes during plant development. In this study, an antisense morpholino oligo microinjection approach was used to characterize the requirement for six specific 14‐3‐3 family members in Xenopus embryogenesis. Microinjection experiments followed by Western blot analysis showed that morpholinos reduced specific 14‐3‐3 protein levels. Embryos lacking specific 14‐3‐3 isoforms displayed unique phenotypic defects. In particular, reduction of 14‐3‐3 tau (τ) protein, and to a lesser extent, 14‐3‐3 epsilon (ϵ), resulted in embryos with prominent gastrulation and axial patterning defects and reduced mesodermal marker gene expression. In contrast, reduction of 14‐3‐3 zeta (ζ) protein caused no obvious phenotypic abnormalities. Reduction of 14‐3‐3 gamma (γ) protein resulted in eye defects without gastrulation abnormalities. Therefore, individual 14‐3‐3 genes have separable functions in vertebrate embryonic development. Developmental Dynamics 235:1761–1776, 2006. © 2006 Wiley‐Liss, Inc.
Inhibition of SMAD2 expression prevents murine palatal fusion
Authors: Shiomi Nobuyuki , Cui Xiao‐Mei , Yamamoto Tadashi , Saito Takashi , Shuler Charles F.
Published: April 2006

Transforming growth factor (TGF)‐beta 3 is known to regulate the disappearance of murine medial edge epithelium (MEE) during palatal fusion. Our previous studies showed that SMAD2, a TGF‐beta signaling mediator, was expressed and phosphorylated primarily in the MEE and that SMAD2 phosphorylation in the MEE was temporospatially regulated by TGF‐beta 3. The goal of this study was to examine the requirement for SMAD2 to complete the developmental events necessary for palatal fusion. SMAD2 expression was inhibited with Smad2 siRNA transfection into palatal tissues in vitro. The results showed that Smad2 siRNA transfection resulted in the maintenance of MEE cells in the palatal midline. Western blot and immunofluorescence analyses confirmed that the endogenous SMAD2 and phospho‐SMAD2 levels were reduced following siRNA transfection. The SMAD3 level was not altered by the Smad2 siRNA transfection. The persistence of the MEE and the decreased SMAD2/phospho‐SMAD2 levels were coincident with increased MEE cell proliferation. Addition of exogenous TGF‐beta 3 increased p‐SMAD2 level but not the total SMAD2 level. Therefore, exogenous TGF‐beta 3 was not able to induce p‐SMAD2 enough to rescue the palatal phenotype in the Smad2 siRNA group. The results indicated that the endogenous SMAD2 level is crucial in the regulation of disappearance of MEE during palatal fusion. Developmental Dynamics 235:1785–1793, 2006. © 2006 Wiley‐Liss, Inc.
Expression of 18‐wheeler in the follicle cell epithelium affects cell migration and egg morphology in Drosophila
Authors: Kleve Cassandra D. , Siler Dominic A. , Syed Samreen K. , Eldon Elizabeth D.
Published: April 2006

The Drosophila ovary is a model system for examining the genetic control of epithelial morphogenesis. The somatic follicle cells form a polarized epithelium surrounding the 16‐cell germ line cyst. The integrity of this epithelium is essential for the successful completion of oogenesis. Reciprocal signaling between germ line and somatic cells establishes embryonic and eggshell polarity. The follicle cells are responsible for shaping the egg and secreting the eggshell. Follicle cells at the boundary between the nurse cells and the oocyte migrate centripetally to cover the anterior end of the oocyte and secrete the operculum. Dorsal anterior main body follicle cells undergo elaborate patterning to produce the dorsal appendages. We have examined the expression of the Toll‐like receptor, 18‐wheeler (18w), in the ovary and find it to be restricted to subpopulations of follicle cells. Females carrying loss‐of‐function 18w mutant clones in their ovaries show delayed follicle cell migrations. The eggs laid by such females also show morphological defects in egg shape and dorsal appendage morphology. We propose that the 18W protein plays an adhesive or signaling role in regions of the epithelium engaged in cell migration. Developmental Dynamics 235:1953–1961, 2006. © 2006 Wiley‐Liss, Inc.
Jag2‐Notch1 signaling regulates oral epithelial differentiation and palate development
Authors: Casey Liam M. , Lan Yu , Cho Eui‐Sic , Maltby Kathleen M. , Gridley Thomas , Jiang Rulang
Published: April 2006

During mammalian palatogenesis, palatal shelves initially grow vertically from the medial sides of the paired maxillary processes flanking the developing tongue and subsequently elevate and fuse with each other above the tongue to form the intact secondary palate. Pathological palate–mandible or palate–tongue fusions have been reported in humans and other mammals, but the molecular and cellular mechanisms that prevent such aberrant adhesions during normal palate development are unknown. We previously reported that mice deficient inJag2, which encodes a cell surface ligand for the Notch family receptors, have cleft palate associated with palate–tongue fusions. In this report, we show thatJag2is expressed throughout the oral epithelium and is required for Notch1 activation during oral epithelial differentiation. We show that Notch1 is normally highly activated in the differentiating oral periderm cells covering the developing tongue and the lateral oral surfaces of the mandibular and maxillary processes during palate development. Oral periderm activation of Notch1 is significantly attenuated during palate development in theJag2mutants. Further molecular and ultrastructural analyses indicate that oral epithelial organization and periderm differentiation are disrupted in theJag2mutants. Moreover, we show that theJag2mutant tongue fused to wild‐type palatal shelves in recombinant explant cultures. These data indicate that Jag2‐Notch1 signaling is spatiotemporally regulated in the oral epithelia during palate development to prevent premature palatal shelf adhesion to other oral tissues and to facilitate normal adhesion between the elevated palatal shelves. Developmental Dynamics 235:1830–1844, 2006. © 2006 Wiley‐Liss, Inc.
Isolation and characterization of a novel gene, xMADML, involved in Xenopus laevis eye development
Authors: Elkins Matthew B. , Henry Jonathan J.
Published: April 2006

We have identified Xenopus MADM‐like (xMADML), a Xenopus laevis gene related to the murine MADM and the human NRBP genes. xMADML is expressed throughout early development and is expressed most strongly in the developing lens and more weakly in the retina and other anterior tissues. We demonstrate that disruption of xMADML translation by means of morpholino injection results in impaired retina and lens development. Reciprocal transplantation of the presumptive lens ectoderm between morpholino‐injected embryos and those injected solely with a dextran lineage tracer demonstrates that xMADML is necessary in both the lens and the retina for correct development of these eye tissues. Analysis of gene expression after knockdown of xMADML revealed significant alterations in the expression of some genes, including Pax6, xSix3, Sox2, and Sox3, suggesting that xMADML plays a role in regulating gene expression during development of the eye. This investigation is the first in vivo study examining the developmental role of this novel gene and reveals an important role of xMADML in eye tissue development and differentiation. Development Dynamics 235:1845–1857, 2006. © 2006 Wiley‐Liss, Inc.
Visualizing neurons one‐by‐one in vivo: Optical dissection and reconstruction of neural networks with reversible fluorescent proteins
Authors: Aramaki Shinsuke , Hatta Kohei
Published: April 2006

A great many axons and dendrites intermingle to fasciculate, creating synapses as well as glomeruli. During live imaging in particular, it is often impossible to distinguish between individual neurons when they are contiguous spatially and labeled in the same fluorescent color. In an attempt to solve this problem, we have taken advantage of Dronpa, a green fluorescent protein whose fluorescence can be erased with strong blue light, and reversibly highlighted with violet or ultraviolet light. We first visualized a neural network with fluorescent Dronpa using the Gal4‐UAS system. During the time‐lapse imaging of axonal navigation, we erased the Dronpa fluorescence entirely; re‐highlighted it in a single neuron anterogradely from the soma or retrogradely from the axon; then repeated this procedure for other single neurons. After collecting images of several individual neurons, we then recombined them in multiple pseudo‐colors to reconstruct the network. We have also successfully re‐highlighted Dronpa using two‐photon excitation microscopy to label individual cells located inside of tissues and were able to demonstrate visualization of a Mauthner neuron extending an axon. These “optical dissection” techniques have the potential to be automated in the future and may provide an effective means to identify gene function in morphogenesis and network formation at the single cell level. Developmental Dynamics 235:2192–2199, 2006. © 2006 Wiley‐Liss, Inc.
Relationship Between the Nearest‐Neighbor Exchange Coupling Constants and the Number of Exchange Interactions in the Cyano‐Bridged MnMo6(CN)18 Cluster: Density Functional Theory Calculations
Authors: Zhang Yi‐Quan , Luo Cheng‐Lin
Published: April 2006

A theoretical density functional study of the relationship between the nearest‐neighbor MnMo constants and the number of exchange interactions in the cyano‐bridged K[(Me3tacn)6MnMo6(CN)18](ClO4)3 cluster is presented. Two approaches (the first approach consisted of evaluating the exchange coupling constant Jij between two paramagnetic metal centers i and j in the hexanuclear molecule by calculating the energy differences between the highest and broken‐symmetry spin states of a model molecule in which metal atoms except for i and j are substituted by diamagnetic YIII cations, and the second is to calculate the different spin‐state energies of hexanuclear complexes and use the Heisenberg Hamiltonian to obtain the exchange coupling constants between different metal centers) show that the antiferromagnetic coupling interactions between nearest neighbors weaken with the increase of the number of exchange interactions. The various θ angles have an influence on the interactions between the nearest‐neighbor MoMn but do not change the trend between J12 and the number of exchange interactions. Moreover, Kahn’s qualitative theory succeeded in being applied to interpret the trend.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Rational Design and Control of the Dimensions of Channels in Three‐Dimensional, Porous Metal‐Organic Frameworks Constructed with Predesigned Hexagonal Layers and Pillars
Authors: Li Cui‐Jin , Hu Sheng , Li Wei , Lam Chi‐Keung , Zheng Yan‐Zhen , Tong Ming‐Liang
Published: April 2006

New three‐dimensional, microporous metal‐organic frameworks exhibiting reversible water adsorption, constructed from hexagonal [Co3(imda)2] layers and N,N′‐pillars, in which the dimensions of the channels are rationally adjustable by varying the lengths of pillars, have been designed, hydrothermally synthesized, and characterized. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Reactivity of the Inversely Polarised Arsaalkenes R–As=C(NMe2)2 {R = [(η5‐C5Me5)(CO)2Fe], tBuC(O)} Towards Vinylidene Complexes [η5‐(C5H5)(CO)(NO)W=C=C(H)R] (R = Ph, tBu)
Authors: Weber Lothar , Bayer Philipp , Noveski Gabriel , Stammler Hans‐Georg , Neumann Beate
Published: April 2006

The reaction of the vinylidene complexes [(C5H5)(CO)(NO)W=C=C(H)R] (10a: R = tBu; 10b: R = Ph) with the arsaalkene tBuC(O)–As=C(NMe2)2 (11) afforded the novel η2‐1‐arsaallene complexes [η2‐{tBuC(O)–As=C=C(H)R}W(CO)(NO)C5H5] (13: R = tBu; 15: R = Ph). Similarly, treatment of 10a with the ferrioarsaalkene [(C5Me5)(CO)2Fe–As=C(NMe2)2] (12) led to the formation of [η2‐{[(C5Me5)(CO)2Fe]–As=C=C(H)tBu}W(CO)(NO)(C5H5)] (14), whereas combination of 12 and 10b yielded the carbene complex [(C5H5)(CO)(NO)W=C(NMe2)C(Ph)=C(H)NMe2] (16) in high yield instead of the anticipated arsaallene complex. The novel compounds 13, 14, 15 and 16 were characterised by elemental analyses and by means of spectroscopy (IR, 1H, 13C NMR). Moreover, the molecular structures of 14 and 15 were elucidated by X‐ray diffraction analyses. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Triple‐Decker Transition‐Metal Complexes (CnHn)M(B6C)M(CnHn) (M = Fe, Ru, Mn, Re; n = 5, 6) Containing Planar Hexacoordinate Carbon Atoms
Authors: Li Si‐Dian , Miao Chang‐Qing , Ren Guang‐Ming , Guo Jin‐Chang
Published: April 2006

A density functional theory investigation is presented in this work on a new class of triple‐decker complexes (CnHn)M(B6X)M(CnHn) (M = Fe, Ru, Mn, Re; X = B, C, N; n = 5, 6) containing almost perfect planar hexacoordinate carbon atoms and other planar hexacoordinate nonmetals at the centers of the B6X middle‐deckers. Effective d–π coordination interactions between the partially filled 3d orbitals of the transition‐metal center and the delocalized π orbitals of the three parallel ligands maintain the stabilities of these triple‐decker complexes. The strong IR absorption peaks of (CnHn)M(B6X)M(CnHn) complexes mainly originate from the in‐plane and off‐plane vibrations of their planar hexacoordinate nonmetal centers. The results obtained in this work provide a possible new approach to characterize planar hexacoordinate carbon‐containing systems in future experiments and expand the structural domain of transition‐metal complexes by introducing inorganic B6X middle‐deckers into traditional sandwich‐type structures. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
N‐Carboxymethylated 6,7‐Dimethoxy‐4‐trifluoromethylcarbostyrils as Fluorescence Markers for Amino Acids, Peptides, Amino Carbohydrates and Amino Polysaccharides
Authors: Badgujar Naresh S. , Pazicky Marek , Traar Pedro , Terec Anamaria , Uray Georg , Stadlbauer Wolfgang
Published: April 2006

The highly fluorescent 6,7‐dimethoxy‐3‐trifluoromethylcarbostyril 2 was regioselectively carboxymethylated with bromoacetates 4 at N‐1 to give esters of type 5 in good yield. After saponification to 8, succinimidoyl (OSu) esters 9 were prepared. Dyestuffs 9 were reacted in slightly basic aqueous media under mild conditions with free amino acids, esters and peptides to give the fluorescently labeled amino acid derivatives 11 and 13 in good yields. Similarly, aminoglucose and chitosane reacted to form the fluorescently labeled carbohydrates 15 and 17. Fluorescence quantum yields of 0.3–0.4, their photostability and a pH‐independence between 3 and 10 make this class of compounds useful for linking to biological samples in aqueous media.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
A Facile Synthesis of 1‐Substituted‐1H‐1,2,3,4‐Tetrazoles Catalyzed by Ytterbium Triflate Hydrate
Authors: Su Wei‐Ke , Hong Zhi , Shan Wei‐Guang , Zhang Xing‐Xian
Published: April 2006

A series of 1‐substituted 1H‐1,2,3,4‐tetrazole compounds have been synthesized in good yields from amines, triethyl orthoformate, and sodium azide through the catalyzed reaction with Yb(OTf)3. Some of the 1‐susbstituted 1H‐1,2,3,4‐tetrazole compounds showed strong phytocidal activity. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)