bluuebunny/crossref_metadata_2025 huggingface dataset:
Hierarchical Self‐Assembly in Molecularly Ordered Phenylene‐Bridged Mesoporous Organosilica Nanofilaments
Authors: Camarota Beatrice , Mann Stephen , Onida Barbara , Garrone Edoardo
Published: October 2007

Herein we report on the mechanism of formation of a hybrid phenylene‐bridged hexagonally ordered mesoporous organosilica with crystal‐like walls (CW‐Ph‐HMM). Electron microscopy and X‐Ray diffraction studies indicate that the formation of CW‐Ph‐HMM involves the surfactant‐mediated hydrothermal transformation of an amorphous organosilica precursor and that the final product is hierarchically ordered. Significantly, the material is in the form of submicrometre‐thick sheets that consist of co‐aligned aggregates of needle‐like particles (up to 500 nm in length and 50 nm in width). The results suggest that preferential growth along the channel direction of the hexagonally ordered mesostructure is coupled with the propagation of molecular periodicity in the pore walls. Together, these factors give rise to the growth of highly anisotropic primary nanofilaments that become co‐aligned to produce micrometer‐thick sheets consisting of a periodic array of mesoscopic channels oriented perpendicular to the surface of the flake‐like particles.
Rab23 GTPase is expressed asymmetrically in Hensen's node and plays a role in the dorsoventral patterning of the chick neural tube
Authors: Li Naixin , Volff Jean‐Nicolas , Wizenmann Andrea
Published: October 2007

The mouse Rab23 protein, a Ras‐like GTPase, inhibits signaling through the Sonic hedgehog pathway and thus exerts a role in the dorsoventral patterning of the spinal cord. Rab23 mouse mutant embryos lack dorsal spinal cord cell types. We cloned the chicken Rab23 gene and studied its expression in the developing nervous system. Chick Rab23 mRNA is initially expressed in the entire neural tube but retracts to the dorsal alar plate. Unlike in mouse, we find Rab23 in chick already expressed asymmetrically during gastrulation. Ectopic expression of Rab23 in ventral midbrain induced dorsal genes (Pax3, Pax7) ectopically and reduced ventral genes (Nkx2.2 and Nkx6) without influencing cell proliferation or neurogenesis. Thus, in the developing brain of chick embryos Rab23 acts in the same manner as described for the caudal spinal cord in mouse. These data indicate that Rab23 plays an important role in patterning the dorso‐ventral axis by dorsalizing the neural tube. Developmental Dynamics 236:2993–3006, 2007. © 2007 Wiley‐Liss, Inc.
Early embryonic expression patterns of the mouse Flamingo and Prickle orthologues
Authors: Crompton Lucy A. , Du Roure Camille , Rodriguez Tristan A.
Published: October 2007

The Drosophila melanogaster proteins Flamingo and Prickle act in the planar cell polarity (PCP) pathway, which is required for acquisition of epithelial polarity in the wing, eye, and epidermis. In mammals, PCP signaling has been shown to regulate cell movements and polarity in a variety of tissues. Here, we show that the murine Flamingo orthologues Celsr1–3 and the Prickle orthologues Prickle1, Prickle2, and Testin have dynamic patterns of expression during pregastrulation and gastrulation stages. Celsr1 is expressed in the anterior visceral endoderm and nascent mesoderm, Celsr2 and Celsr3 mark the prospective neuroectoderm, Prickle1 is expressed in the primitive streak and mesoderm, Prickle2 in the node, and Testin in the anterior visceral endoderm, the extraembryonic ectoderm, primitive streak, and mesoderm. Analysis of a gene‐trap mutation in Testin indicates that this gene is not required for embryogenesis; therefore, other Prickle homologues may compensate for its function during development. Developmental Dynamics 236:3137–3143, 2007. © 2007 Wiley‐Liss, Inc.
Sensitivity to visual and auditory stimuli in children with developmental dyslexia
Authors: King Bernardine , Wood Clare , Faulkner Dorothy
Published: October 2007

This study considered the extent to which 23 children with dyslexia differed from 23 reading age (RA) and 23 chronological age (CA) matched controls in their ability to make temporal judgements about auditory and visual sequences of stimuli, and in the speed of their reactions to the onsets and offsets of visual and auditory stimuli. The children with dyslexia were slower (p = 0.039) than the CA controls in their reactions to non‐verbal auditory onsets (tones), were less able to recognize the first stimulus of a sequence of tones (p = 0.022), and were less accurate in identifying the initial phoneme of a sequence of three (p < 0.001). These characteristics may be manifestations of an impaired temporal processing system for rapid auditory stimuli. CA controls responded more quickly to tone onsets than to tone offsets (p = 0.025), but the dyslexic and RA groups showed no significant difference (p > 0.05) in their reaction times to onsets and offsets of these non‐verbal auditory stimuli. Dyslexic readers showed impairment compared with CA controls in responding to the last of a sequence of three non‐verbal visual stimuli (shapes), p = 0.02. Reaction times in the visual and auditory onset and offset tasks were richly intercorrelated in the control groups, but the dyslexic group did not show as many significant correlations in reaction times between the auditory and visual domains, or between the onset and offset RTs within each modality. These results suggest that there may be a less integrated cross‐modal and intra‐modal temporal system in children with dyslexia than in controls. In many of the measures in this study, the performance of the dyslexic group resembled that of the RA control group but differed from CA controls, which implies a developmental delay. The possibility that such a cognitive delay may be related to an underlying neurological disorder is discussed. Copyright © 2007 John Wiley & Sons, Ltd.
An examination of the concept of central coherence in women with anorexia nervosa
Authors: Lopez Carolina , Tchanturia Kate , Stahl Daniel , Booth Rhonda , Holliday Joanna , Treasure Janet
Published: October 2007

Objective:

To examine central coherence (local and global processing) in women with anorexia nervosa (AN).

Method:

42 women with AN and 42 healthy women (HC) completed neuropsychological testing measuring visuospatial and verbal aspects of central coherence: Rey‐Osterrieth Complex Figure (RCFT), Embedded Figures Test (EFT), Homograph Reading Test (HRT), and Sentence Completion Task (SCT).

Results:

People with AN displayed superior performance on the EFT and poorer performance in RCFT with the exception of accuracy in the copy trial. Long hesitations in the SCT were observed. Verbal coherence tasks were not sensitive enough to detect coherence anomalies in AN.

Conclusion:

Women with AN have strengths in tasks requiring local processing (EFT) and weaknesses on tasks benefited by global processing (RCFT and SCT). These results are consistent with the weak central coherence account. This trait might play a role in the maintenance of AN and can be addressed in specific clinical interventions. © 2007 by Wiley Periodicals, Inc. Int J Eat Disord 2008
Assessment of the frequency domain decomposition technique by forced‐vibration tests of a full‐scale structure
Authors: Lamarche C. P. , Paultre P. , Proulx J. , Mousseau S.
Published: October 2007

Dynamic characteristics of buildings are of utmost importance in earthquake engineering. The vibration periods are required to determine design loads, and damping is necessary in time‐history analysis. These parameters are generally obtained through forced‐vibration tests (FVTs) or after a seismic event in the case of permanently instrumented structures. However, for large civil engineering structures, FVTs are often too costly or practically difficult, and ambient or output‐only methods are used. This paper describes a comparison between ambient and FVTs carried out on a two‐story building. Results from both testing methods are compared and discussed in order to assess the vibration properties estimates obtained with the frequency domain decomposition technique. Copyright © 2007 John Wiley & Sons, Ltd.
Development of a novel biocompatible polymer system for extended drug release in a next‐generation drug‐eluting stent
Authors: Udipi Kishore , Chen Mingfei , Cheng Peiwen , Jiang Kevin , Judd Diane , Caceres Alejandra , Melder Robert J. , Wilcox Josiah N.
Published: October 2007

Drug‐eluting stents have proven superior to bare metal stents with lower restenosis rates. Local delivery of drugs from these stents is achieved in most cases with the help of biostable polymer coatings. However, since the polymer coating remains in the body well after all the drug is released, patients can potentially develop hypersensitivity to these polymers—leading to complications such as late‐stent thrombosis. It is therefore important that the polymers are designed to be biocompatible and well tolerated by the body. The polymer coatings are also expected to be robust and provide good control over elution of the desired drug. This paper describes the development of a unique, proprietary polymer blend system, specially designed to meet these requirements. Mutually compatible, free‐radical‐initiated elastomeric polymers were designed to provide a robust coating and offer a steady, sustained release of the highly hydrophobic drug zotarolimus over an extended period. The polymer blend system is also well tolerated by the hydrophilic environment in vivo, as demonstrated through porcine studies. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
A porous PCL scaffold promotes the human chondrocytes redifferentiation and hyaline‐specific extracellular matrix protein synthesis
Authors: Garcia‐Giralt N. , Izquierdo R. , Nogués X. , Perez‐Olmedilla M. , Benito P. , Gómez‐Ribelles J. L. , Checa M. A. , Suay J. , Caceres E. , Monllau J. C.
Published: October 2007

The redifferentiation, proliferation, and hyaline‐specific extracellular matrix (ECM) protein synthesis of chondrocytes cultured in a polycaprolactone (PCL) scaffold were analyzed. Gene expression of the type II collagen and aggrecan was assessed by real‐time PCR in cells from PCL scaffolds, monolayer, and pellet cultures. The proliferative activity was assessed using Ki‐67 immunodetection, and the chondrocytic differentiation was evaluated using S‐100 immunodetection. The synthesis and deposition into scaffold pores of type II collagen and glycosaminoglycan were analyzed by immunohistochemistry and Alcian blue staining, respectively. All parameters were assessed throughout 28 days of cultures maintained in either fetal bovine serum‐containing medium (FCM) or Insulin‐Transferrin‐Selenium‐containing medium (ICM). Expression of the type II collagen gene was lower in FCM cultures than in ICM cultures for all culture systems (p < 0.05). Moreover, PCL scaffolds cultured in ICM were able to induce collagen gene expression more efficiently than pellet and monolayer cultures. Aggrecan gene expression did not vary significantly between mediums and three‐dimensional system cultures, but in ICM cultures, the monolayer cultures had significantly higher levels of aggrecan gene expression than did either the PCL or pellet cultures. Chondrocytes cultured in PCL scaffolds or pellets with FCM did not proliferate to a great extent but did maintain their differentiated phenotype for 28 days. Levels of cartilage ECM protein synthesis and deposition into the scaffold pores were similar among PCL and pellet cultures grown in FCM and in ICM. In conclusion, chondrocytes seeded into PCL scaffolds, cultured in ICM, efficiently maintained their differentiated phenotype and were able to synthesize cartilage‐specific ECM proteins. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Feasibility of prefabricated vascularized bone graft using the combination of FGF‐2 and vascular bundle implantation within hydroxyapatite for osteointegration
Authors: Nakasa Tomoyuki , Ishida Osamu , Sunagawa Toru , Nakamae Atsuo , Yokota Kazunori , Adachi Nobuo , Ochi Mitsuo
Published: October 2007

The aim of this study was to demonstrate the feasibility of the prefabricated vascularized bone graft using an interconnected porous calcium hydroxyapatite ceramic (IP‐CHA) in combination with vascular bundle implantation and basic fibroblast growth factor (FGF‐2) administration in rabbit model. Thirty Japanese white rabbits were used. To make a prefabricated bone graft, the saphenous artery and vein were passed through the hole of the IP‐CHA. Hundred micrograms of FGF‐2 was administered into the IP‐CHA before implanting the vascular bundle. First and foremost, the IP‐CHA was placed subcutaneously in the medial thigh of rabbits for 4 weeks. In the experimental group, a prefabricated vascularized bone graft was used while IP‐CHA alone was used in the control group. Second, the prefabricated vascularized bone graft was transplanted from the subcutaneous implanted site into the medial femoral condyle defect of the same rabbit and IP‐CHA alone was implanted as the control graft in a different animal. At 4 weeks posttransplantation, bone union with host bone could be observed in the experimental group. However, the area of bone formation of the control group was significantly higher than in the experimental at 2 and 4 weeks posttransplantation. We conclude that the prefabricated vascularized bone graft when transplanted into a bone defect showed the ability for bone union with the host bone, although further studies are needed to accelerate the process of bone formation. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Blending polysaccharides with biodegradable polymers. I. Properties of chitosan/polycaprolactone blends
Authors: García Cruz Dunia M. , Gomez Ribelles José L. , Salmerón Sánchez Manuel
Published: October 2007

Blends of polycaprolactone (PCL) and chitosan (CHT) were prepared by casting from a solution. CHT and PCL were dissolved by using acetic acid/water mixtures. Both solutions were slowly mixed to cast blend films containing 10%, 20%, 30%, and 40% by weight of CHT. PCL and CHT form phase separated blends. The phase morphology is in large extent controlled by the casting procedure. Even if casting of the film starts from a clear solution, the solvent composition determines the form in which phase separation takes place and consequently the morphology of the resulting blend after solvent evaporation. The blend containing 20% CHT presents cocontinuous phases. The sample presents a high elastic modulus even at temperatures above melting of PCL. Blends with higher CHT contents consist of disperse PCL domains in a CHT matrix and the contrary occurs in the blend containing 10% CHT in which disperse CHT domains with a network morphology appear inside the spherulites of PCL. In all the blends, the nucleation effect of CHT accelerates the crystallization of PCL from the melt, although in the blends with high CHT contents a part of the PCL mass included in large domains might not be affected by the presence of CHT. The sample containing 20% CHT has a peculiar behavior with respect to the crystallization of PCL, only a small part of PCL crystallizes in isothermal treatments although this fraction crystallizes faster than in the rest of the blends. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Biomimetic processing of bioactive interface on silicon substrates
Authors: Chong S. C. , Loo J. , Lee P. S. , Ma J.
Published: October 2007

To facilitate the implantation of silicon‐based devices in vivo, the presence of a biocompatible and bioactive coating is noted to be an essential factor. The objective of this present work is therefore to explore a relatively simple and low cost process to induce the formation of bioactive apatite on silicon. The formation of apatite on silicon was carried out by a biomimetic approach on two orientations of silicon wafer, namely (100) and (111). The samples are functionalized by chemical etching, followed by incubation in a simulated body fluid. Scanning electron microscopy, energy dispersive X‐ray analysis, X‐ray diffraction analysis, and X‐ray photoelectron spectroscopy were carried out. It was found that the growth of apatite is dependent on the orientation of the silicon wafer. Cell culturing experiment further verified the biological performance of the apatite‐coated silicon samples. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
A review of materials, fabrication methods, and strategies used to enhance bone regeneration in engineered bone tissues
Authors: Stevens Brian , Yang Yanzhe , Mohandas Arunesh , Stucker Brent , Nguyen Kytai Truong
Published: October 2007

Over the last decade, bone engineered tissues have been developed as alternatives to autografts and allografts to repair and reconstruct bone defects. This article provides a review of the current technologies in bone tissue engineering. Factors used for fabrication of three‐dimensional bone scaffolds such as materials, cells, and biomolecular signals, as well as required properties for ideal bone scaffolds, are reviewed. In addition, current fabrication techniques including rapid prototyping are elaborated upon. Finally, this review article further discusses some effective strategies to enhance cell ingrowth in bone engineered tissues; for example, nanotopography, biomimetic materials, embedded growth factors, mineralization, and bioreactors. In doing so, it suggests that there is a possibility to develop bone substitutes that can repair bone defects and promote new bone formation for orthopedic applications. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Effect of several factors on peracetic acid pretreatment of sugarcane bagasse for enzymatic hydrolysis
Authors: Zhao Xue‐bing , Wang Lei , Liu De‐hua
Published: October 2007

BACKGROUND: Lignocellulose should undergo pretreatment to enhance its enzymatic digestibility before being saccharified. Peracetic acid (PAA) is a strong oxidant that can remove lignin under mild conditions. The sulfuric acid in the PAA solution also can cause degradation of hemicelluloses. The objective of the present work is to investigate the effect of several factors on peracetic acid pretreatment of sugarcane bagasse.

RESULTS: It was found that PAA charge, liquid/solid (l/s) ratio, temperature, time, interactions between PAA charge and l/s ratio, temperature and time, all had a very significant effect on the enzymatic conversion ratio of cellulose. The relative optimum condition was obtained as follows: PAA charge 50%, l/s ratio 6:1, temperature 80 °C and time 2 h. More than 80% of the cellulose in bagasse treated under the above conditions was converted to glucose by cellulase of 20 FPU g−1 cellulose. Compared with H2SO4 and NaOH pretreatments under the same mild conditions, PAA pretreatment was the most effective for enhancement of enzymatic digestibility.

CONCLUSION: PAA pretreatment could greatly enhance the enzymatic digestibility of sugarcane bagasse by removing hemicelluloses and lignin, but removal of lignin was more helpful. This study can serve as a step to further optimization of PAA pretreatment and understanding the mechanism of enhancement of enzymatic digestibility. Copyright © 2007 Society of Chemical Industry
Amino acid oxidase‐catalysed resolution and Pictet–Spengler reaction towards chiral and rigid unnatural amino acids
Authors: Benz Peter , Wohlgemuth Roland
Published: October 2007

BACKGROUND: The biosynthesis of structurally complex isoquinoline alkaloids and other natural products occurs via aromatic amino acids such as tyrosine, and chiral and rigid amino acids. These structures are also key building blocks of many active pharmaceutical ingredients. The aim of this work was the exploration of a rapid and straightforward route to chiral 6‐hydroxy‐1,2,3,4‐tetrahydroisoquinoline‐3‐carboxylic acid.

RESULTS: The preparation of (S)‐meta‐tyrosine from racemic meta‐tyro‐ sine with aminoacidoxidase has been developed with ee > 99% and 88% yield. The combination of this resolution with a subsequent Pictet–Spengler reaction enables straightforward and versatile access to chiral (S)‐6‐hydroxy‐1,2,3,4‐tetrahydroisoquinoline‐3‐carboxylic acid in 30% yield.

CONCLUSIONS: This new short chemoenzymatic route to (S)‐6‐hydroxy‐1,2,3,4‐tetrahydroisoquinoline‐3‐carboxylic acid from commercially available DL‐m‐tyrosine is more convenient than other chemical procedures and establishes a new link between the pool of easily accessible racemic aromatic amino acids and the corresponding chiral rigidified amino acids, which are of interest as structural elements of many active pharmaceutical ingredients. These results facilitate synthetic access to a range of active pharmaceutical ingredients and metabolites in chiral form from the oxidation of amino acids. This advances the opportunities to study the molecular interactions with enzymes, receptors and effectors more precisely than with the racemic forms. Copyright © 2007 Society of Chemical Industry
Determination of particle number and brightness using a laser scanning confocal microscope operating in the analog mode
Authors: Dalal Rooshin B. , Digman Michelle A. , Horwitz Alan F. , Vetri Valeria , Gratton Enrico
Published: October 2007

We describe a method to obtain the brightness and number of molecules at each pixel of an image stack obtained with a laser scanning microscope. The method is based on intensity fluctuations due to the diffusion of molecules in a pixel. For a detector operating in the analog mode, the variance must be proportional to the intensity. Once this constant has been calibrated, we use the ratio between the variance and the intensity to derive the particle brightness. Then, from the ratio of the intensity to the brightness we obtain the average number of particles in the pixel. We show that the method works with molecules in solution and that the results are comparable to those obtained with fluctuation correlation spectroscopy. We compare the results obtained with the detector operating in the analog and photon counting mode. Although the dynamic range of the detector operating in the photon counting mode is superior, the performance of the analog detector is acceptable under common experimental conditions. Since most commercial laser scanning microscopes operate in the analog mode, the calculation of brightness and number of particles can be applied to data obtained with these instruments, provided that the variance is proportional to the intensity. We demonstrate that the recovered brightness of mEGFP, independent of concentration, is similar whether measured in solution or in two different cell types. Furthermore, we distinguish between mobile and immobile components, and introduce a method to correct for slow variations in intensity. Microsc. Res. Tech., 2008. © 2007 Wiley‐Liss, Inc.
List‐coloring the square of a subcubic graph
Authors: Cranston Daniel W. , Kim Seog‐Jin
Published: October 2007

The square G2 of a graph G is the graph with the same vertex set G and with two vertices adjacent if their distance in G is at most 2. Thomassen showed that every planar graph G with maximum degree Δ(G) = 3 satisfies χ(G2) ≤ 7. Kostochka and Woodall conjectured that for every graph, the list‐chromatic number of G2 equals the chromatic number of G2, that is, χl(G2) = χ(G2) for all G. If true, this conjecture (together with Thomassen's result) implies that every planar graph G with Δ(G) = 3 satisfies χl(G2) ≤ 7. We prove that every connected graph (not necessarily planar) with Δ(G) = 3 other than the Petersen graph satisfies χl(G2) ≤8 (and this is best possible). In addition, we show that if G is a planar graph with Δ(G) = 3 and girth g(G) ≥ 7, then χl(G2) ≤ 7. Dvořák, Škrekovski, and Tancer showed that if G is a planar graph with Δ(G) = 3 and girth g(G) ≥ 10, then χl(G2) ≤6. We improve the girth bound to show that if G is a planar graph with Δ(G) = 3 and g(G) ≥ 9, then χl(G2) ≤ 6. All of our proofs can be easily translated into linear‐time coloring algorithms. © 2007 Wiley Periodicals, Inc. J Graph Theory 57: 65–87, 2008
Scaled Gromov hyperbolic graphs
Authors: Jonckheere Edmond , Lohsoonthorn Poonsuk , Bonahon Francis
Published: October 2007

In this article, the δ‐hyperbolic concept, originally developed for infinite graphs, is adapted to very large but finite graphs. Such graphs can indeed exhibit properties typical of negatively curved spaces, yet the traditional δ‐hyperbolic concept, which requires existence of an upper bound on the fatness δ of the geodesic triangles, is unable to capture those properties, as any finite graph has finite δ. Here the idea is to scale δ relative to the diameter of the geodesic triangles and use the Cartan–Alexandrov–Toponogov (CAT) theory to derive the thresholding value of δdiam below which the geometry has negative curvature properties. © 2007 Wiley Periodicals, Inc. J Graph Theory 57: 157–180, 2008
Understanding rehospitalization risk: Can hospital discharge be modified to reduce recurrent hospitalization?
Authors: Strunin Lee , Stone Meg , Jack Brian
Published: October 2007

BACKGROUND

A high rate of unnecessary rehospitalization has been shown to be related to a poorly managed discharge processes.

OBJECTIVE

A qualitative study was conducted in order to understand the phenomenon of frequent rehospitalization from the perspective of discharged patients and to determine if activities at the time of discharge could be designed to reduce the number of adverse events and rehospitalization.

DESIGN

Semistructured, open‐ended interviews were conducted with 21 patients during their hospital stay at Boston Medical Center. Interviews assessed continuity of care after discharge, need for and availability of social support, and ability to obtain follow‐up medical care.

RESULTS

Difficult life circumstances posed a greater barrier to recuperation than lack of medical knowledge. All participants were able to describe their medical condition, the reasons they were admitted to the hospital, and the discharge instructions they received. All reported the types of medications being taken or the conditions for which the medications were prescribed. Recuperation was compromised by factors that contribute to undermining the ability of patients to follow their doctors' recommendations including support for medical and basic needs, substance use, and limitations in the availability of transportation to medical appointments. Distress, particularly depression, further contributed to poor health and undermined the ability to follow doctors' recommendations and the discharge plans.

CONCLUSIONS

Discharge interventions that assess the need for social support and provide access and services have the potential to reduce chronic rehospitalization. Journal of Hospital Medicine 2007;2:297–304. © 2007 Society of Hospital Medicine.
Current research and future challenges in urban mesoscale modelling
Authors: Martilli Alberto
Published: October 2007

Increases in environmental problems linked to urbanization and increases in computational power are proposed as the main mechanisms behind positive feedbacks between experimental investigation and numerical modelling in mesoscale urban studies. The focus here is on the modelling, with a description of state‐of‐the‐art techniques used to parameterize urban‐induced dynamical and thermal effects in mesoscale models. An analysis of possible future developments in urban mesoscale modelling is presented. Emphasis is laid on the link between mesoscale and microscale models, increases in numerical resolution, and improvement in anthropogenic heat flux estimation. Copyright © 2007 Royal Meteorological Society
Cirque infills in the Khibiny Mountains, Kola Peninsula, Russia — palaeoglaciological interpretations and modern analogues in East Antarctica
Authors: Hättestrand Clas , Kolka Vasili , Johansen Nina
Published: October 2007

We report here on cirque infills mapped in the Khibiny Mountains, Kola Peninsula, Russia. Cirque infills are morainic deposits located near the headwalls of valleys and cirques. Their location and shape, often with concave margins towards the valley side, indicate that they were deposited by ice flowing up‐valley, into the mountains, rather than by local glaciers. We suggest that they formed during the last deglaciation, when Khibiny was a nunatak and Fennoscandian ice sheet lobes extended into valleys and cirques of the massif. The formation of cirque infills is probably more related to ice sheet dynamic factors, occurring when the ice margin retreated from the cirques, than to climate‐driven interruption in the ice‐marginal retreat. Glacial conditions similar to those prevalent when the Khibiny cirque infills were formed, occur today in Antarctica where the ice sheets engulf nunatak ranges. In Heimefrontfjella, Antarctica, the formation of supraglacial moraines at the head of cirques are linked to blue‐ice conditions, indicating locally low accumulation rates, a dry continental climate and sublimation dominated ablation. We suggest that these Antarctic moraines are modern analogues of cirque infills on the Kola Peninsula, and possibly, that the cirque infills may be used as palaeoenvironmental indicators. Copyright © 2007 John Wiley & Sons, Ltd.
The role of the Iceland Ice Sheet in the North Atlantic during the late Quaternary: a review and evidence from Denmark Strait
Authors: Andrews John T.
Published: October 2007

Investigations indicate that the Iceland Ice Sheet was reduced in size during MIS 3 but readvanced to the shelf break at the LGM. Retreat occurred very rapidly around 15 k–16 k cal. yr BP. By contrast, the margin of the ice sheet on the East Greenland shelf, north of the Denmark Strait, was at or close to the shelf break during MIS 3 and 2 and retreat starting ∼17 k cal. yr BP. Quantitative X‐ray diffraction analysis of the <2 mm sediment fraction was undertaken on 161 samples from Iceland and East Greenland diamictons, and from cores on the slopes and margins of the Denmark Strait. Weight% mineralogical data are used in a principal component analysis to differentiate sediments derived from the two margins. The first two PC axes explain 52% of the variance. These associations are used to characterise sediments as being affiliated with (a) Iceland, (b) East Greenland or (c) mixed. The contribution from Iceland becomes prominent during MIS 2. The extensive outcrop of early Tertiary basalts on East Greenland between 68° and 71° N is an alternative source for basaltic clasts and North Atlantic sediments with εNd(0) values close to ±0. Copyright © 2007 John Wiley & Sons, Ltd.
High-power continuous wave and passively Q-switched laser operations of a Nd:GGG crystal
Authors: Qin L J , Tang D Y , Xie G Q , Dong C M , Jia Z T , Tao X T
Published: October 2007

We report on the continuous wave (CW) and passive Q-switching performance of a high-power diode-pumped Nd:GGG laser. A CW output power of 7.20 W was obtained under an absorbed pump power of 14.97 W, which gives a slop efficiency of 52.7%. With a Cr4+ doped yttrium aluminum garnet crystal as the saturable absorber, the shortest passively Q-switched pulse width, largest pulse energy, and highest peak power achieved were 7.7 ns, 126.25 μJ, and 15.5 kW, respectively.
Tunable multiwavelength Brillouin-Erbium fiber laser with intra-cavity pre-amplified Brillouin pump
Authors: Al-Mansoori M H , Mahdi M A , Zamzuri A K
Published: October 2007

We have demonstrated a new configuration of Brillouin-Erbium fiber laser, in which the Brillouin pump is pre-amplified within the laser cavity before entering the single-mode fiber. By using this simple scheme, a lower external Brillouin pump power is required to create the Brillouin gain and suppresses the laser cavity modes. The proposed laser structure exhibits a wide tuning range of 13 nm from 1597 nm to 1610 nm with 1480 nm pump power of 100 mW. The number of channels obtained within this wavelength range is 14 channels with 0.089 nm spacing.
Positively negative: the impact of negativity upon the political consumer
Authors: Lloyd Jenny
Published: October 2007

For years there has been an ongoing debate as to the role and impact that ‘marketing’ has had on politics. Yet, it is the case that many of the concepts associated with the field of marketing have real relevance and have, in fact, been employed within the field of political campaigning for many decades. This is an empirical paper that focuses upon the concept of political brands and the impact that current trends in campaign strategy, and in particular the growth and continued use of negative campaigning, have upon them. Using a constructivist grounded theory approach, the implications associated with such activity are examined and, in particular, its effect upon the consumer/brand relationship.

Within the consideration of the results, it becomes clear that political brands' use of negative campaigning is somewhat shortsighted; offering short‐term gains but at the cost of long‐term damage not only to their brand image but also to the wider democratic system as it stands. In a search for political ‘brands’ that more effectively meet their needs, there appears a tendency for political consumers to now look outside of the conventional political sector. The emergent concept of the ‘negative brand’ is explored together with the implications for political consumers, political brands and the wider field of conventional party politics.

Copyright © 2007 John Wiley & Sons, Ltd.
Stable nitrogen isotope values in arid‐land kangaroos correlated with mean annual rainfall: potential as a palaeoclimatic indicator
Authors: Pate F. D. , Anson T. J.
Published: October 2007

Bone collagen stable nitrogen isotope values are reported for modern kangaroos (Macropus spp.) from eight field sites along a 1160 km south–north transect from temperate coastal to arid interior South Australia, in order to investigate δ15N tissue variability in relation to rainfall and relative humidity. Mean annual rainfall along the transect ranges from 775 mm at Mount Gambier in the southeastern coast to 176 mm at Innamincka in the arid northern interior, while 3pm relative humidity ranges from 73% at coastal Flinders Chase to 36% at Innamincka. In arid habitats (176–238 mm rainfall), the δ15N values of kangaroo bone collagen become more positive in relation to decreasing mean annual rainfall (r2 = 0.98), while there is only a weak correlation with relative humidity (r2 = 0.67). In contrast, in temperate and semi‐arid coastal habitats (350–775 mm), there is no correlation between kangaroo bone collagen δ15N values and rainfall (r2 = 0.0011) or between δ15N values and relative humidity (r2 = 0.0035). Thus, in South Australia, kangaroo bone collagen δ15N values do not show a simple linear correlation with either rainfall or relative humidity across all habitats. These results suggest that stable nitrogen isotope analyses of herbivore bones obtained from archaeological and palaeontological sites may provide a reliable proxy for past rainfall values in arid‐land ecosystems. Copyright © 2007 John Wiley & Sons, Ltd.
The depsipeptide technique applied to peptide segment condensation: Scope and limitations
Authors: Coin Irene , Schmieder Peter , Bienert Michael , Beyermann Michael
Published: October 2007

A promising application of the depsipeptide technique has recently been proposed to provide ideal conditions for segment condensation, in that coupling of peptides bearing a C‐terminal depsipeptide unit occurs without giving rise to epimerization at the activated amino acid. This is due to the low tendency of the activated depsipeptide units, in contrast to the corresponding peptide segments, to form optically labile oxazolones. In this work we demonstrate that coupling of depsipeptides via base‐assisted activation using HBTU occurs not only without loss of configuration, but even much faster than the coupling of the corresponding all‐amide segments. Nevertheless, when the coupling of long depsipeptide segments proceeds slowly, we uncovered the occurrence of β‐elimination at the activated depsipeptide unit, in an extent dependent on the presence of base in the system and on the type of the solvent. Beta‐elimination was completely suppressed by using carbodiimide/HOBt activation in a non‐polar solvent (DCM), and in more polar media it was limited by substituting TMP for DIEA during HBTU activation, or using particular solvent mixtures (such as DMSO/toluene) for activation via carbodiimide. Finally, we show the application of C‐terminal pseudoprolines, in comparison with that of depsipeptide units, to segment coupling. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd.
Electrospray ionization ion‐trap time‐of‐flight tandem mass spectrometry of two furofurans: sesamin and gmelinol
Authors: Yan Guoquan , Li Qianrong , Tan Huarong , Ge Tiefei
Published: October 2007

High‐resolution electrospray ionization multistage tandem mass spectrometry (MS1–7) in positive ion mode was used to determine the accurate masses and the fragmentation pathways of two furofurans, sesamin and gmelinol. The protonated molecules [M+H]+ were absent in the conventional mass spectra of both compounds, but two characteristic ions, [M+H−H2O]+ and [M+H−H2]+, were always observed. Successive losses of CH2O and CO are the common characteristic fragmentations. Based on the exact masses acquired from 21 different tandem mass spectra, two or three fragmentation pathways for each compound are proposed. The consecutive losses of two H2O molecules and one H2 molecule readily take place from the furan rings for both sesamin and gmelinol, resulting in the absence of the protonated molecules in the single‐stage experiments. HCHO loss is observed at least three times in the tandem mass spectra, mainly from methylenedioxy groups (OCH2O) for sesamin but only from tetrahydrofuran rings for gmelinol. Moreover, CO loss is found at least three times in the tandem mass spectra of both sesamin and gmelinol from the 3,4‐methylenedioxyphenyl (ArOCH2O) moieties for sesamin and from both the dimethoxyphenyl and the tetrahydrofuran ring moieties for gmelinol. In addition, the disubstituted benzyl cation ArCH at m/z 135 for sesamin and at m/z 151 for gmelinol was found in the MS3 spectra of both sesamin and gmelinol, which is very helpful in the identification of the compositions of 3,4‐disubstituted groups on the benzene rings of the furofurans. Copyright © 2007 John Wiley & Sons, Ltd.
Study of interactions between arsenicals and thioredoxins (human and E. coli) using mass spectrometry
Authors: Wang Zhongwen , Zhang Hongquan , Li Xing‐Fang , Le X. Chris
Published: October 2007

Thioredoxin (Trx) plays an important role in achieving redox balances in cells and protecting the cells from oxidative damage. However, little is known about how arsenic affects Trx chemically. It is conceivable that trivalent arsenicals may bind to Trx, which has a highly conserved ‐CysGlyProCys‐ sequence. The objective of this study is to characterize the binding of seven arsenic species with Trx from E. coli and humans, using two mass spectrometry techniques. The arsenic‐Trx complexes and the free arsenicals were well separated by size‐exclusion liquid chromatography (LC) and detected with inductively coupled plasma mass spectrometry (ICPMS). The LC/ICPMS analyses showed that the trivalent arsenic species were able to form complexes with both human and E. coli Trx. Determination of binding constants indicated that affinity to Trx was higher for monomethylarsonous acid (MMAIII) and phenylarsine oxide (PhAsIII) than inorganic arsenite (iAsIII) and dimethylarsinous acid (DMAIII), probably because MMAIII and PhAsIII were able to form stable complexes by binding to two vicinal cysteines in the ‐CysGlyProCys‐ region of the Trx. The complexes of arsenicals with both human and E. coli Trx were further characterized by nano‐electrospray tandem mass spectrometry. Binding stoichiometries for different arsenic species were consistent with the available cysteine residues in the Trx. Mass spectral evidence also suggests that the pentavalent arsenicals could be reduced by Trx. This study provides the first detailed chemical characterization of the interactions between Trx and arsenic species. Copyright © 2007 John Wiley & Sons, Ltd.
Tightening McDonald cerclage suture under sonographic guidance
Authors: Hershkovitz R. , Burstein E. , Pinku A.
Published: October 2007

Objective

The technical factors contributing to failure of cerclage are not fully understood. The aims of this study were to assess the possibility of tightening the McDonald cerclage under ultrasound guidance and to examine the width and shape of the cervical canal before and after tightening the suture.

Methods

A prospective study was performed. The sole indication for cerclage placement was clinical history of cervical insufficiency. Cervical length and canal width were measured by transvaginal ultrasound, at 12–14 weeks' gestation, with the patient's bladder empty, after which the cerclage was performed. Tightening of the suture was performed under sonographic guidance (transabdominal or transrectal) until the cervical canal disappeared from view. After tying the suture, cervical length and the canal width were assessed sonographically.

Results

Fifty‐eight patients were enrolled in the study; 50 patients had singleton pregnancies and eight patients carried twins. The mean cervical length at the beginning of the procedure was 31 ± 13 mm (median 30 mm, range 15–48 mm). The mean cervical canal width was 2.1 ± 0.9 mm (median 2.0 mm, range 0.9–4.5 mm). The mean addition to the length of the cervical canal after the procedure was 11 ± 0.8 mm (median 1.0, range 8–19 mm). No complications were noted during the procedures. An interesting sonographic finding was an hourglass shape of the cervical canal after the procedure in 16 patients. Of 58 patients, 47 delivered at term, 10 delivered preterm and one miscarried at 18 weeks. Nine of 10 patients with preterm delivery had an hourglass‐shaped sonographic appearance of the cervical canal after the procedure.

Conclusions

McDonald cerclage can be tightened under ultrasound guidance. The sonographic appearance of an hourglass shape of the cervical canal following suture tightening may be a risk factor for preterm delivery. Copyright © 2007 ISUOG. Published by John Wiley & Sons, Ltd.
Sexual reproductive biology of the endangered Japanese red maple (Acer pycnanthum)
Authors: Saeki Ikuyo
Published: October 2007

Japanese red maple, Acer pycnanthum, is an endangered wetland species having dioecious sex expression. Prior studies conclude that land development has caused severe loss of habitat, and seedling regeneration is rare. However, information is lacking on sexual reproduction, which is the first critical stage of regeneration. My research objective was to describe flowering and fruiting characteristics of Japanese red maple, focusing on tree sizes at the onset of flowering, factors affecting flowering regularity and fruit abundance, periodicity of fruit production, and sex ratio. In a study of a young population, Japanese red maple initiated flowering at a small size under 100% light intensity. Initiation of flowering occurred at relatively lower height in males than females, and males flowered more regularly than females. A survey of 1,106 clones from 46 natural populations revealed that male clones were significantly more abundant than female clones. In a 4‐year study of mature populations, nearly all clones flowered regularly, and fruit abundance of dominant females was typically high. Fruit abundance at the population level also remained high, although fruit abundance of individual female clones varied year by year. Therefore, sexual reproductive ability is highly vigorous. Sex ratio exhibited a major deviation from a 1:1 ratio in populations with a small number of clones. In conservation planning, we should prioritize avoidance of an unbalanced sex ratio by increasing population sizes. In addition, populations having many clones >40 cm dbh with large, well‐lighted crowns have a high potential of regular and abundant seed production.
Surfactant‐Mediated Catalytic Determination of Fe(II) in Herbal and Pharmaceutical Products
Authors: Khan Muhammad Nasiruddin , Siddiqui Zaheeruddin , Uddin Fahim
Published: October 2007

In the present work, the catalyzed oxidation of neutral red (NR) by bromate was used to work out a kinetic‐based analytical method as an alternative technique for the determination of Fe(II) in real and synthetic samples. A use of a surfactant, N‐dodecylpyridinium chloride enhanced the sensitivity of the reaction by becoming involved in the reaction mechanism and providing a more suitable reaction environment. The iron‐catalyzed oxidation of NR with potassium bromate was studied kinetically by using a fixed time method. The reaction was followed by measuring the decrease in absorbance at 535 nm. The use of a surfactant in the analytical run showed a five times increase in the sensitivity of the method. It served as a ready reservoir of NR by increasing its solubilization. The salt effect, pH, and reagent concentration were also investigated to achieve a more selective and sensitive analytical procedure. Under optimized conditions (4.2 × 10−5 mol L−1 NR, 1.4 × 10−3 mol L−1 KBrO3, 1.5 × 10−2 mol L−1 cationic surfactant, 0.5 mol L−1 LiCl and pH 2.60 at 30 °C), iron(II) was determined in the range 0.1–0.5 μg mL−1 with a detection limit of 0.019 μg mL−1 and a relative standard deviation (n = 6) 1.02% for 0.2 μg mL−1 Fe(II). The influence of foreign ions on the accuracy of the results was investigated. The developed method is extremely sensitive, selective and simple. The method was applied successfully to the determination of iron in the herbal pharmaceutical and synthetic samples. The results showed good agreement with those obtained by atomic absorption spectrophotometry.
Multiple Archaean to Early Palaeozoic events of the northern Gondwana margin witnessed by detrital zircons from the Radzimowice Slates, Kaczawa Complex (Central European Variscides)
Authors: TYSZKA RAFAŁ , KRYZA RYSZARD , ZALASIEWICZ JAN A. , LARIONOV ALEXANDER N.
Published: October 2007

SIMS dating of detrital zircons from the stratigraphically enigmatic Radzimowice Slates of the Kaczawa Mountains (Sudetes, SW Poland), near the eastern termination of the European Variscides, has yielded age populations of: (1) 493–512 Ma, corresponding to late Cambrian to early Ordovician magmatism and constraining a maximum depositional age; (2) between 550 and 650 Ma, reflecting input from diverse Cadomian sources; and (3) older inherited components ranging toc.3.3 Ga, with age spectra similar to those from Gondwanan North Africa. The new data show that the Radzimowice Slates cannot form a Proterozoic base to the Kaczawa Mountains succession, as suggested by earlier models, but was deposited, at the earliest, as an extensional basin-fill, during a relatively late stage of the break-up of this part of northern Gondwana.
Nonlinear dynamics of the viscoelastic Kolmogorov flow
Authors: BISTAGNINO A. , BOFFETTA G. , CELANI A. , MAZZINO A. , PULIAFITO A. , VERGASSOLA M.
Published: October 2007

The weakly nonlinear dynamics of large-scale perturbations in a viscoelastic flow is investigated both analytically, via asymptotic methods, and numerically. For sufficiently small elasticities, dynamics is ruled by a Cahn–Hilliard equation with a quartic potential. Physically, this amounts to saying that, for small elasticities, polymers do not alter the purely hydrodynamical mechanisms responsible for the nonlinear dynamics in the Newtonian case (i.e. without polymers). The approach to the steady state is quantitatively similar to the Newtonian case as well, the dynamics being ruled by the same kink–antikink interactions as in the Newtonian limit. The above scenario does not extend to large elasticities. We found a critical value above which polymers drastically affect the dynamics of large-scale perturbations. In this latter case, a new dynamics not observed in the Newtonian case emerges. The most evident fingerprint of the new dynamics is the slowing down of the annihilation processes which lead to the steady states via weaker kink–antikink interactions. In conclusion, polymers strongly affect the large-scale dynamics. This takes place via a reduction of drag forces we were able to quantify from the asymptotic analysis. This suggests a possible relation of this phenomenon with the dramatic drag-reduction effect taking place in the far turbulent regime.