bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of knowledge protection, knowledge ambiguity, and relational capital on alliance performance
Authors: Lee Shu‐Cheng , Chang Shao‐Nung , Liu Chang‐Yung , Yang Jie
Published: January 2007

This paper examines the impact of knowledge protection, knowledge ambiguity, and relational capital on alliance performance of 95 Taiwan‐based companies. The results show that knowledge protection exerts significant positive effect on knowledge ambiguity and relational capital and relational capital mediates the relationship between knowledge ambiguity and alliance performance. This paper concludes with a discussion of the implications and limitations of the research. Copyright © 2007 John Wiley & Sons, Ltd.
Supercontinuum generation in a microstructured optical fiber by picosecond self Q-switched mode-locked Nd:GdVO4 laser
Authors: Lin J-H , Lin K-H , Hsu C-C , Yang W H , Hsieh W-F
Published: January 2007

An effective supercontinuum (SC) generation is demonstrated by injecting picosecond self Q-switched mode-locked Nd:GdVO4 laser pulses into a 1-m long microstructured fiber. The laser is operated at wavelength 100-nm away from the longer zero-dispersion of this dual zero-dispersion wavelength microstructured fiber. The phenomena of modulation instability, stimulated Raman effect, and dispersive wave can be sequentially observed from experimental results, leading to spectral broadening as pumping increases.
Effects of skin temperature on lesion size in fractional photothermolysis
Authors: Laubach Hans , Chan Henry H. , Rius Francisca , Anderson R. Rox , Manstein Dieter
Published: January 2007

Background and Objectives

Fractional photothermolysis is a new concept in cutaneous re‐modeling whereby laser‐induced microscopic zones of thermal injury (MTZ—Microscopic Treatment Zones) are surrounded by normal, viable tissue. This unique thermal damage pattern allows re‐epithelialization in less than 24 hours. To increase patient comfort level during the procedure of fractional photothermolysis, simultaneous skin cooling has been proposed and is now extensively used. The purpose of this in vitro study was to examine the influence of skin temperature on the diameter of the epidermal microthermal zone and the extent of thermal injury per unit area. The determination of the changes in these parameters that are due to skin temperature will allow the better control and understanding of fractional photothermolysis at different skin temperatures.

Materials and Methods

Fractional photothermolysis was performed with a 1,550 nm fiber laser (Fraxel SR® Laser) with 10 mJ per pulse on full‐thickness cadaver skin. The skin samples were brought prior to exposure to temperatures that ranged from 0 to 45°C. The epidermis of the skin samples was separated by dispase treatment, stained for thermal damage by NBTC stain, and lesion diameter was assessed by a blinded investigator.

Results

The average MTZ diameter exhibits a positive, linear relationship with skin temperature (R2 = 0.904, P < 0.0001). As the skin temperature increases from 0 to 45°C. The MTZ diameter increases from 93 to 147 µm (58%), and the MTZ area from 6,870 to 17,050 µm2 (148%).

Conclusion

The skin temperature affects the size of epidermal MTZs during fractional photothermolysis and is an important variable factor. The use of simultaneous skin cooling increases patient comfort; however, as it also decreases MTZ size, it may interfere with treatment efficacy. The control of skin temperature is necessary to provide a consistent outcome and to be able to compare treatments. Lasers Surg. Med. 39:14–18, 2007. © 2007 Wiley‐Liss, Inc.
A Facile Approach to Single‐Wall Carbon Nanotube/Poly(allylamine) Nanocomposites
Authors: Kim Jong‐Boem , Premkumar Thathan , Lee Kyungjae , Geckeler Kurt E.
Published: January 2007

A facile approach to polymer nanocomposites with single‐wall carbon nanotubes and cationic polymers is reported. The composite material was synthesized by producing carboxylic acid groups at the nanotube termini followed by a reaction with poly(allylamine) in water. Fourier transform infrared spectral and thermogravimetric analyses corroborate that the poly(allylamine) chains were wrapped on the surface of the carbon nanotubes. The scanning electron microscopic (SEM) image shows that the nanotubes were dispersed with little aggregation, thus, strongly suggesting that the poly(allylamine) chains have covered the single‐wall carbon nanotubes, which was further evidenced by transmission electron microscopy. The composites are soluble in water, and this solubilization process opens up new opportunities in the solution chemistry on pristine nanotubes.

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Preparation of Polyaniline Nanotubes via “Thin Glass Tubes Template” Approach and its Gas Response
Authors: Gao Yu , Yao Shuang , Gong Jian , Qu Lunyu
Published: January 2007

PANI nanotubes were successfully prepared by using thin glass tubes as a single template in the presence of H4SiW12O40 and ammonium persulfate, which were used as dopant and oxidant, respectively, in this system. The structure and morphology of the PANI were characterized by IR spectrum, XRD pattern, SEM images, and TEM images. The inner diameter of PANI nanotubes was between 50 and 100 nm. This method employed here was a simple and effective way to prepare multifunctional PANI nanotubes. The gas response of the PANI nanotubes to a series of chemical vapors such as NH3, N2H4, and (C2H5)3N was studied. The results indicate that the PANI nanotubes show superior performance as chemical sensor.

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13C NMR spectroscopy of some third‐generation cephalosporins, their synthetic intermediaries and reaction byproducts
Authors: López Miguel A. , Rodríguez Zalua , González Maritza , Tolón Blanca , Avila Rizette , Rodríguez Juan C. , Vélez‐Castro Hermán , Fini Adamo
Published: January 2007

13C NMR spectroscopic data for 25 cephalosporin derivatives were assigned by combination of one‐ and two‐dimensional experiments. The effect of the substitution at C‐3, C‐7 and C‐4 acid group positions on the chemical shifts of the cephem nucleus is discussed. Copyright © 2007 John Wiley & Sons, Ltd.
Triple‐stimulation technique in multifocal neuropathy with conduction block
Authors: Deroide Nicolas , Uzenot David , Verschueren Annie , Azulay Jean‐Philippe , Pouget Jean , Attarian Shahram
Published: January 2007

In patients with multifocal neuropathy with conduction block (CB), CBs located between the root and Erb's point are not detected in nerve conduction studies. We therefore examined whether the triple‐stimulation technique (TST) might provide a useful means of detecting CB proximal to Erb's point. Clinical assessments, extensive nerve conduction studies (NCS), conventional transcranial magnetic stimulation, and TST were performed on 10 patients with multifocal motor neuropathy with CB (MMNCB) and 6 patients with Lewis–Sumner syndrome. Conduction blocks located proximal to Erb's point were detected in 9 patients. Of the CBs, 58% were associated with muscle weakness. The use of TST to detect proximal CB improved the sensitivity of the American Association of Neuromuscular and Electrodiagnostic Medicine criteria for definite or probable MMNCB from 60% to 90%. Thus, the TST is a useful means for detection of proximal CB and gives NCS considerable additional diagnostic power. Muscle Nerve, 2007
Laparoscopic versus open colposuspension for urodynamic stress incontinence
Authors: Tan Emile , Tekkis Paris P. , Cornish Julie , Teoh Tiong G. , Darzi Ara W. , Khullar Vik
Published: January 2007

Aims

Laparoscopic colposuspension aims to alleviate urodynamic stress incontinence whilst minimizing operative morbidity and mortality.

The present study compared laparoscopic to open surgery with regards to short‐term outcomes.

Methods

Meta‐analysis of comparative studies published between 1995 and 2006 of laparoscopic versus open colposuspension was performed. End points evaluated were operative outcomes and subjective/objective cure. A random‐effect model was used and sensitivity analysis performed to account for bias in patient selection.

Results

Sixteen studies matched the selection criteria, reporting on 1,807 patients, of whom 861 (47.6%) underwent laparoscopic and 946 (52.4%) underwent open colposuspension length of hospital stay (WMD = −1.52 days, CI = −2.08, −0.96 days) and return to normal life (WMD = −1.51 weeks, CI = −3.02, 0.01 weeks) were significantly reduced following laparoscopic surgery. These findings remained consistent on sensitivity analysis. Bladder injuries occurred more often in the laparoscopic group (OR = 2.23, CI = 1.11, 4.50), but only with marginal statistical significance. Comparable bladder injury rates were found when studies were matched for quality, year, and randomized trials. Cure rates were similar between the two procedures at 2 years follow‐up.

Conclusion

Laparoscopic colposuspension results in a significant reduction in hospital stay and earlier return to work, with a possible increased risk of bladder injury. When performed by appropriately experienced surgeons it may be a safe option with advantages for the patient, but further randomized controlled trials should be undertaken to evaluate continence in the longer term at 5 years. Neurourol. Urodynam. 26:158–169, 2007. © 2007 Wiley‐Liss, Inc.
Inhibitor of apoptosis proteins are regulated by tumour necrosis factor‐α in malignant pleural mesothelioma
Authors: Gordon GJ , Mani M , Mukhopadhyay L , Dong L , Yeap BY , Sugarbaker DJ , Bueno R
Published: January 2007

Inhibitor of apoptosis proteins (IAPs) are overexpressed by most neoplasms and promote tumour cell survival after a wide variety of apoptotic stimuli elicited via intrinsic (ie mitochondrial) and extrinsic (ie death receptor) pathways. It has previously been reported that one of these proteins, IAP‐1(MIHC/cIAP2), is overexpressed in malignant pleural mesothelioma (MPM) and is responsible for a large degree of the resistance of cultured MPM cells to cisplatin. Subsequent analysis in a larger number of human tumours revealed that additional IAPs (eg IAP‐2/MIHB/cIAP1, livin/ML‐IAP/KIAP, survivin, and XIAP/MIHA/hILP) are also overexpressed in MPM and, with the exception of IAP‐2, have expression patterns that correlate with prognosis. In the present study, potential regulatory mechanisms of IAP genes in MPM were investigated and it was found that tumour necrosis factor‐alpha (TNF‐α) can increase mRNA and protein levels of IAP‐1, IAP‐2, and XIAP, but not livin or survivin in MPM cell lines (n = 4). It was also found that IAP gene expression levels are increased concomitantly with translocation to the nucleus of the TNF‐responsive transcription factor NF‐κB. Co‐incubation of MPM cells with TNF‐α and pyrrolidine dithiocarbamate (PDTC), an NF‐κB inhibitor, prevented TNF‐mediated up‐regulation of IAP gene expression levels. In survival studies, TNF‐α was not toxic to MPM cells at any concentration examined. However, MPM cells exposed to TNF‐α were twice as resistant to cisplatin in dose response survival assays compared with unstimulated controls and were found to have a significantly greater fraction of surviving cells at multiple cisplatin concentrations (p < 0.0087). Finally, it was found that levels of circulating TNF‐α were statistically significantly (p = 0.031) (median 312.5 pg/ml) higher in MPM patients (n = 6) prior to surgical tumour debulking compared with those after surgery (median 0 pg/ml). These results when combined with previous observations by our laboratory and others strongly suggest that IAPs act synergistically with TNF family members to promote survival of MPM tumour cells after exposure to cisplatin and possibly other chemotherapeutic drugs. Copyright © 2007 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Reactivation and risk of sequelae in Langerhans cell histiocytosis
Authors: Pollono Daniel , Rey Guadalupe , Latella Antonio , Rosso Diego , Chantada Guillermo , Braier Jorge
Published: January 2007

Objective

To evaluate disease reactivation in patients with Langerhans cell histiocytosis (LCH) and its impact on adverse sequelae.

Materials and Methods

A retrospective evaluation of 300 patients diagnosed with LCH between 1987 and 2002 with complete response to initial treatment was performed.

Results

Mean age at diagnosis was 5.3 years. With a mean follow‐up of 4.8 years, reactivation of the disease occurred in 29.7% (89/300) of the patients, with two or more reactivations in 34.8% (31/89) of those. Reactivation occurred in 17.4, 36.8, 46.5, and 53.5% of the patients with single‐system unifocal disease (Group A: 161 patients), single‐system multifocal disease (Group B: 53 patients), multi‐system disease without (Group C: 58 patients), and with (Group D: 28 patients) risk‐organ involvement, respectively. The differences between the incidence rates of Groups A and B (P < 0.0004), A and C (P < 0.0001), and A and D (P < 0.0001) were highly significant. The most common reactivation sites involved were bone, middle ear, and skin; reactivation was rare in risk organs (9.5%). The median time between initial complete response and the first reactivation episode was 1 year for Group A, 1.3 years for Group B, and 9 months for Groups C and D. Most reactivation episodes (88%) occurred within the first 2 years of follow‐up. Adverse sequelae were recognized in 242/300 patients: 71% (49/69) of patients with and 25.4% (44/173) without reactivations developed these adverse sequelae (P < 0.0001), respectively. Sites most commonly showing sequelae were bone, middle ear, and hypothalamus (Diabetes Insipidus).

Conclusions

Incidence of reactivation correlates with the stage of the disease at diagnosis. Incidence of sequelae correlates with the occurrence of reactivations. Pediatr Blood Cancer 2007;48:696–699. © 2007 Wiley‐Liss, Inc.
The risk of coronary heart disease in type 2 diabetic patients exposed to thiazolidinediones compared to metformin and sulfonylurea therapy
Authors: Johannes Catherine B. , Koro Carol E. , Quinn Sherry G. , Cutone Jennifer A. , Seeger John D.
Published: January 2007

Purpose

To evaluate whether the risk of coronary heart disease (CHD) differs among adult diabetic patients treated with thiazolidinediones (TZDs) and similar patients treated with combined oral metformin and sulfonylurea (M + S) therapy.

Methods

We conducted a retrospective cohort study involving 25 140 diabetic patients aged 18 and older who had at least one pharmacy claim for a TZD or combined M + S therapy between 1 January 1999 and 30 June 2002. We used propensity score matching to adjust for observable differences between initiators of combined M + S therapy and TZD initiators. The data were analyzed in two ways: first based on the original matched groups, ‘as balanced’, without accounting for switching to another medication during follow‐up, and second based on actual antidiabetic drug use during follow‐up, ‘as treated’. Cox proportional hazards regression and multivariable Poisson regression were performed to compare the risk of CHD events.

Results

In the ‘as balanced’ analysis, the risk for CHD among TZD users relative to combination drug users was close to the null value (adjusted hazard ratio: 1.02, 95% confidence intervals (CI): 0.87–1.20). In the ‘as treated’ analysis, the risk of CHD was similar for periods of current use of TZDs compared to periods of non‐use (incidence rate ratio: 1.10, 95%CI: 0.96–1.25).

Conclusions

These results do not suggest a cardioprotective or deleterious effects of TZDs compared with combined M + S oral therapy on the short‐term CHD event risk in persons with type 2 diabetes after accounting for the greater baseline CHD risk in TZD initiators. Copyright © 2007 John Wiley & Sons, Ltd.
Volume phase transition temperature tuning and investigation of the swelling–deswelling oscillation of responsive microgels
Authors: Li Xin , Zuo Ju , Guo Yanling , Cai Libo , Tang Shuo , Yang Weiben
Published: January 2007

Temperature‐ and pH‐responsive polyampholyte microgels were prepared by an aqueous dispersion polymerization. Scanning electron microscopy and dynamic laser light scattering (DLS) were employed for the characterization of the morphology and size distribution of the microgels. Temperature‐ and pH‐dependent volume phase transitions of the polyampholyte microgels were also investigated using DLS. The microgels showed an interesting swelling–deswelling oscillatory behavior when the pH was varied. An interpretation was proposed for the phenomenon in terms of Coulombic repulsion and hydrophobic hydration. It is of great interest that the volume phase transition temperature (VPTT) of the polyampholyte microgels can be varied by changing the pH. This could be a convenient approach for tuning the VPTT of N‐isopropylacrylamide‐based hydrogels. Copyright © 2007 Society of Chemical Industry
Incorporation of carbon nanotubes into polyethylene by high energy ball milling: Morphology and physical properties
Authors: Gorrasi Giuliana , Sarno Maria , Di Bartolomeo Antonio , Sannino Diana , Ciambelli Paolo , Vittoria Vittoria
Published: January 2007

High energy ball milling (HEBM) was utilized, as an innovative process, to incorporate carbon nanotubes (CNTs) into a polyethylene (PE) matrix avoiding: high temperatures, solvents, ultrasonication, chemical modification of carbon nanotubes. Composites with 1, 2, 3, 5, and 10 wt % of carbon nanotubes were prepared. Films were obtained melting the powders in a hot press. Morphology and physical properties (thermal, mechanical, electrical properties) were evaluated. The used processing conditions allowed to obtain a satisfactory level of dispersion of CNTs into the PE matrix with a consequent improvement of the physical properties of the samples. The thermal degradation was significantly delayed already with 1–2% wt of CNTs. The mechanical properties resulted greatly improved for low filler content (up to 3% wt). The electrical measurements showed a percolation threshold in the range 1–3 wt % of CNTs. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 597–606, 2007
Isothermal crystallization behaviors of isotactic polypropylene nucleated with α/β compounding nucleating agents
Authors: Zhang Yue‐Fei , Xin Zhong
Published: January 2007

Sodium 2,2′‐methylene‐bis(4,6‐di‐tert‐butylphenyl) phosphate (NA40) and N,N‐dicyclohexylterephthalamide (NABW) are high effective nucleating agents for inducing the formation of α‐isotactic polypropylene (α‐iPP) and β‐iPP, respectively. The isothermal crystallization kinetics of iPP nucleated with nucleating agents NABW, NA40/NABW (weight ratio of NA40 to NABW is 1:1) and NA40 were investigated by differential scanning calorimetry (DSC) and Avrami equation was adopted to analyze the experimental data. The results show that the addition of NABW, NA40/NABW and NA40 can shorten crystallization half‐time (t1/2) and increase crystallization rate of iPP greatly. In these three nucleating agents, the α nucleating agent NA40 can shorten t1/2 of iPP by the largest extent, which indicates that it has the best nucleation effect. While iPP nucleated with NA40/NABW compounding nucleating agents has shorter t1/2 than iPP nucleated with NABW. The Avrami exponents of iPP and nucleated iPP are close to 3.0, which indicates that the addition of nucleating agents doesn't change the crystallization growth patterns of iPP under isothermal conditions and the crystal growth is heterogeneous three‐dimensional spherulitic growth. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 590–596, 2007
Elastic instability of slip traces in oxidized thin foils
Authors: Youssef Sami , Fnaiech Mustapha , Bonnet Roland
Published: January 2007

Parallel slip traces are often observed in transmission electron microscopy of oxidized and deformed thin foils, but apparently they have not been reported for foils with thicknesses less than a few tens of nanometers. This situation can be explained by an elastic instability of a dislocation dipole for foil thicknesses lower than a critical threshold value. This value is derived from the knowledge of the elastic field of a dislocation in a three‐layer laminated medium and the minimization of the elastic potential energy of the thin foil. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Towards a more systematic analysis of uncertain user–product interactions in product development: an enhanced user–product interaction framework
Authors: Lu Yuan , den Ouden Elke , Brombacher Aarnout , Geudens Wim , Hartmann Herman
Published: January 2007

For highly innovative products the actual product use is often very uncertain. However, the uncertainty/variability in product use and its impact on product reliability has rarely been explored. The mismatch between the anticipated product use and the actual product use can lead to considerable unexpected technical and non‐technical reliability risks. However, traditional reliability management techniques focus primarily on managing technical reliability risks. This situation results in an increasing amount of no‐fault‐found or fault‐not‐found reports in the highly innovative consumer electronics (CE) industry. Under the time‐to‐market pressure, it is increasingly important to take into consideration the significant factors that determine product use in the early product development process. In the Software Reliability Engineering (SRE) framework, a top‐down approach (operational profile) is used to analyse the product use. However, an operational profile cannot be directly applied to analyse product use for CE products due to the differences between the reliability of software products and that of CE products. This paper proposes an enhanced framework to structurally analyse unexpected user–product interactions for highly innovative CE products. In this framework, the product, user and environmental conditions are used to analyse user–product interactions. This framework has been implemented to analyse user–product interactions by using data from a consumer test of a highly innovative CE product. Copyright © 2007 John Wiley & Sons, Ltd.
Strengthening the teaching‐research linkage in undergraduate courses and programs
Authors: Healey, Mick , Jenkins Alan
Published: January 2007

Faculty need to be supported and encouraged to integrate disciplinary research and scholarship into undergraduate courses and programs in ways that are beneficial to their students' learning.
Promoting inquiry‐based learning about teaching through educational development units
Authors: Kreber Carolin
Published: January 2007

Through their own pedagogically oriented inquiry‐based learning, teachers become better prepared to support an increasingly diverse student population in their learning.
MÜLLER’S QUESTION ON SEMI-PERFECT COMPLETE HEREDITARY NOETHERIAN PRIME RINGS
Authors: Ánh Pham Ngoc , Herbera Dolors
Published: January 2007

A positive answer to a question of Müller is given: any semi-perfect complete hereditary Noetherian prime ring $R$ has a weakly symmetric self-duality sending every ideal $I$ to its cycle-neighbour $X$. Consequently, the factor rings $R/I$ and $R/X$ are isomorphic without using the 1984 results of Dischinger and Müller.
A COUNTEREXAMPLE TO A CONTINUED FRACTION CONJECTURE
Authors: Short Ian
Published: January 2007

It is known that if $a\in\mathbb{C}\setminus(-\infty,-\tfrac14]$ and $a_n\to a$ as $n\to\infty$, then the infinite continued fraction with coefficients $a_1,a_2,\dots$ converges. A conjecture has been recorded by Jacobsen et al., taken from the unorganized portions of Ramanujan’s notebooks, that if $a\in(-\infty,-\tfrac14)$ and $a_n\to a$ as $n\to\infty$, then the continued fraction diverges. Counterexamples to this conjecture for each value of $a$ in $(-\infty,-\tfrac14)$ are provided. Such counterexamples have already been constructed by Glutsyuk, but the examples given here are significantly shorter and simpler.
Referential communication abilities and Theory of Mind development in preschool children
Authors: RESCHES MARIELA , PÉREZ PEREIRA MIGUEL
Published: January 2007

This work aims to analyse the specific contribution of social abilities (here considered as the capacity for attributing knowledge to others) in a particular communicative context. 74 normally developing children (aged 3;4 to 5;9, M=4·6) were given two Theory of Mind (ToM) tasks, which are considered to assess increasing complexity levels of epistemic state attribution: Attribution of knowledge-ignorance (Pillow, 1989; adapted by Welch-Ross, 1997) and Understanding of False-belief (Baron Cohen, Leslie & Frith, 1985). Subjects were paired according to their age and level of performance in ToM tasks. These dyads participated in a referential communication task specially designed for this research. The resulting communicative interchanges were analysed using a three-level category system (pragmatic functions, descriptive accuracy, and ambiguity of messages). The results showed significant differences among subjects with different levels of social comprehension regarding the type of communicative resources used by them in every category level. In particular, understanding of false belief seems to be the most powerful predictor of changes in the children’s development of communicative competence.
Three is not always a crowd: contexts of joint attention and language
Authors: BENIGNO JOANN P. , CLARK LAURA , FARRAR M. JEFFREY
Published: January 2007

This study examined 32 children’s (M age=1;8 years) engagement in joint attention (JA) and the relation between JA and vocabulary size across mother–child (MC) and mother–child–sibling (MCS) contexts. In the MCS context, mothers engaged in JA more with one child than both children; they engaged in less JA with target child than they did in the MC context. JA style was generally unrelated across the contexts. Coordinated JA and children’s vocabulary were significantly related only for the MCS context. Findings suggest the number of social partners influences JA dynamics and multi-child contexts can be positive language learning environments.
The information in third-person /s/: acquisition across dialects of American English
Authors: DE VILLIERS JILL G. , JOHNSON VALERIE E.
Published: January 2007

The production of third-person /s/ on English verbs seems to be ahead of comprehension. Mainstream American English (MAE) is contrasted with African American English (AAE), in which /s/ is rarely supplied. Two studies explored what information children get solely from /s/ on the end of a verb. Sixty-five MAE- and 65 AAE-speaking four- to seven-year-olds participated in one of two experimental picture-choice comprehension studies. Neither group of four-year-olds could use the /s/ to determine if the event was generic rather than past tense on a verb (e.g. cuts/cut), or whether it was a verb or a noun compound as in The penguin dresses/The penguin dress. MAE-speakers do not use the information in third-person /s/ alone until age five, and not reliably until age six years. In keeping with AAE production, AAE-speaking children do not use the information in /s/ at all in this age range.
Regional earthquake as a trigger for enhanced volcanic activity: Evidence from MODIS thermal data
Authors: Harris Andrew J. L. , Ripepe Maurizio
Published: January 2007

The magnitude 6.4 earthquake that occurred in Java on 26 May 2006 provided us with data capable of revealing an immediate eruptive response at two Javanese volcanoes, Merapi and Semeru. The availability of pre‐processed thermal data for volcanic hot spots detected by the Moderate Resolution Imaging Spectrometer (MODIS), and provided on http://hotspot.higp.hawaii.edu, allowed us to produce heat and volume flux time series for these two erupting volcanoes covering a 35‐day period spanning the earthquake. Our results revealed a coupled response by the volcanoes to the earthquake, both experiencing increases in heat and volume flux beginning 3 days after the earthquake, with the response lasting 9 days. The response was felt at both volcanoes as a factor of two‐to‐three increase in the rate of volumetric output, after which output returned to the pre‐response rates. This implies that the earthquake triggered enhanced output at two erupting volcanoes 50 and 300 km distant from the earthquake epicenter and separated from each other by ∼260 km.
The 27‐day variations in stratospheric ozone and temperature: New MLS data
Authors: Ruzmaikin A. , Santee M. L. , Schwartz M. J. , Froidevaux L. , Pickett H. M.
Published: January 2007

We use new data obtained by the Microwave Limb Sounder (MLS) onboard of Aura spacecraft to investigate variations in stratospheric ozone and temperature concurrent with the 27‐day variations of solar UV irradiance, measured simultaneously by the Solar Radiation and Climate Experiment (SORCE) during the declining phase of solar activity. Using Empirical Mode Decomposition we determine the latitudinal and height distributions of the 27‐day modes for ozone and temperature and find that these modes are enhanced in the lower tropical stratosphere, and at high latitudes in winter.
Impact of the Indian Ocean SST basin mode on the Asian summer monsoon
Authors: Yang Jianling , Liu Qinyu , Xie Shang‐Ping , Liu Zhengyu , Wu Lixin
Published: January 2007

Following an El Niño event, a basin‐wide warming takes place over the tropical Indian Ocean, peaks in late boreal winter and early spring, and persists through boreal summer. Our observational analysis suggests that this Indian Ocean warming induces robust climatic anomalies in the summer Indo‐West Pacific region, prolonging the El Niño's influence after tropical East Pacific sea surface temperature has returned to normal. In response to the Indian Ocean warming, precipitation increases over most of the basin, forcing a Matsuno‐Gill pattern in the upper troposphere with a strengthened South Asian high. Near the ground, the southwest monsoon intensifies over the Arabian Sea and weakens over the South China and Philippine Seas. An anomalous anticyclonic circulation forms over the subtropical Northwest Pacific, collocated with negative precipitation anomalies. All these anomaly patterns are reproduced in a coupled model simulation initialized with a warming in the tropical Indian Ocean mixed layer, indicating that the Indian Ocean warming is not just a passive response to El Niño but important for summer climate variability in the Indo‐West Pacific region. The implications for seasonal prediction are discussed.
On the characteristics of subtropical fronts in the North Atlantic
Authors: Ullman D. S. , Cornillon P. C. , Shan Z.
Published: January 2007

The characteristics of surface temperature (SST) fronts in the subtropical frontal zone (STCZ) in the North Atlantic were investigated using a time series of front data produced by an edge‐detection algorithm applied to 18 years of 9.3 km resolution NOAA/NASA AVHRR Pathfinder SST imagery. Front probability, averaged over subregions of the STCZ, varies seasonally with highest probability in early spring in the western part of the region. In the eastern part of the region, maximum probability occurs in late spring to early summer, and the annual cycle in front probability is far less robust, being nearly absent prior to 1991. The location and strength of the fronts across the entire STCZ varies strongly with season, moving southward (northward) and strengthening (weakening) in winter/spring (summer). From estimates of the cross‐frontal SST step and gradient, the cross‐frontal scale of SST variability at fronts is estimated to be approximately 30 km. The monthly mean total meridional SST step across the STCZ is partitioned into a component due to frontal pixels and a component due to the background SST gradient at nonfrontal pixels, with approximately 30% of the total step attributable to the SST step across fronts. While the total meridional step is largest in winter due to the meridional gradient in surface heat flux, the frontal contribution lags the total step by 2 months or more in the western part of the STCZ. This suggests a frontogenesis mechanism requiring the presence of a background meridional SST gradient rather than one arising from surface heat flux gradients alone.
Three forms of variability in Argentine Basin ocean bottom pressure
Authors: Hughes C. W. , Stepanov V. N. , Fu L.‐L. , Barnier B. , Hargreaves G. W.
Published: January 2007

Ocean bottom pressure data are examined from a year‐long deployment of two bottom pressure recorders, separated by 417 km, in the Argentine Basin. Three forms of variability are found. At high frequencies (periods shorter than 2 hours) the signal appears to be due to gravity wave propagation with the waves preferentially coming from the west. At intermediate frequencies (periods between 2 hours and 12 days), the two records are highly coherent and in phase, reflecting large‐scale coherent fluctuations which are well reproduced in a barotropic ocean model. However, the dominant mode is at a period of 20 days, with a phase lag of about 90–100° between the two records, consistent with the a mode of variability previously inferred from satellite altimetry and current meters, although the slightly shorter period is consistent with the suggestion that more than one mode contributes to the altimeter observations. Comparison with altimetry demonstrates that aliasing of higher‐frequency signals is not a significant source of error and confirms that a previously used altimetry mapping technique reduces the apparent amplitude of the mode. The pressure records show a transport change of about 280 Sv over one 12‐day period, and altimetry suggests that regions of higher variability exist. The mode is only weakly excited in barotropic models but is strongly excited in a baroclinic model with a realistic eddy field, suggesting that it is intrinsically linked to interactions between eddies, mean flow, and topography.
On the accuracy of North Atlantic temperature and heat storage fields from Argo
Authors: Hadfield R. E. , Wells N. C. , Josey S. A. , Hirschi J. J‐M.
Published: January 2007

The accuracy with which the Argo profiling float dataset can estimate the upper ocean temperature and heat storage in the North Atlantic is investigated. A hydrographic section across 36°N is used to assess uncertainty in Argo‐based estimates of the temperature field. The root‐mean‐square (RMS) difference in the Argo‐based temperature field relative to the section measurements is about 0.6°C. The RMS difference is smaller, less than 0.4°C, in the eastern basin and larger, up to 2.0°C, toward the western boundary. In comparison, the difference of the section with respect to the World Ocean Atlas (WOA) is 0.8°C. For the upper 100 m, the improvement with Argo is more dramatic, the RMS difference being 0.56°C, compared to 1.13°C with WOA. The Ocean Circulation and Climate Advanced Model (OCCAM) is used to determine the Argo sampling error in mixed layer heat storage estimates. Using OCCAM subsampled to typical Argo sampling density, it is found that outside of the western boundary, the mixed layer monthly heat storage in the subtropical North Atlantic has a sampling error of 10–20 Wm−2 when averaged over a 10° × 10° area. This error reduces to less than 10 Wm−2 when seasonal heat storage is considered. Errors of this magnitude suggest that the Argo dataset is of use for investigating variability in mixed layer heat storage on interannual timescales. However, the expected sampling error increases to more than 50 Wm−2 in the Gulf Stream region and north of 40°N, limiting the use of Argo in these areas.
A methodological approach to characterize the resilience of aquatic ecosystems with application to Lake Annecy, France
Authors: Pinault J.‐L. , Berthier F.
Published: January 2007

We propose a methodological approach to characterize the resilience of aquatic ecosystems with respect to the evolution of environmental parameters as well as their aptitude to adapt to forcings. This method that is applied to Lake Annecy, France, proceeds in three stages. First, according to the depth, variations of physicochemical parameters versus time are separated into three components related to (1) energy transfer through the surface of the lake, (2) the flow of rivers and springs that feed the lake, and (3) long‐term evolution of the benthic zone as a consequence of mineral and organic matter loads. Second, dynamics of the lake are deduced by analyzing the physicochemical parameter components related to the three boundary conditions. Third, a stochastic process associated with the transfer models aims to characterize the resilience of the lakes according to forcings. For Lake Annecy, whose dynamics are representative of oligotrophic stratified lakes controlled by decarbonation processes where turnover and mixing occurring once a year in winter, the major consequence is the impoverishment of dissolved oxygen in deep water in autumn due to a temperature increase of the surface water in summer. The simulation raises relevant questions about whether a connection exists between physicochemical parameters and global warming, which should not induce harmful consequences on water quality and biodiversity in deep water. This methodological approach is general since it does not use any physical conceptual model to predict the hydrosystem behavior but uses directly observed data.
The NMDA and AMPA/KA Receptors are Involved in Glutamate-Induced Alterations of Occludin Expression and Phosphorylation in Brain Endothelial Cells
Authors: András Ibolya E , Deli Mária A , Veszelka Szilvia , Hayashi Kentaro , Hennig Bernhard , Toborek Michal
Published: January 2007

Glutamate levels increase dramatically in cerebral ischemia and stroke. This may lead to opening of the blood–brain barrier (BBB) and induce further brain damage. Because endothelial tight junctions are critical elements of the BBB integrity, the aim of this study was to investigate the mechanisms of glutamate-induced alterations of the tight-junction protein occludin in cultured brain microvascular endothelial cells (BMECs). Transient exposure to glutamate resulted in cellular redistribution of occludin, followed by a decrease in the total level of this protein and diminished barrier function of BMECs. Inhibition of the N-methyl-d-aspartate (NMDA) or alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate/kainate (AMPA/KA) receptors attenuated glutamate-induced changes in occludin redistribution but not in the total protein levels. Treatment with glutamate also increased tyrosine phosphorylation and decreased threonine phosphorylation of occludin. Inhibition of the NMDA receptors by MK-801 partially protected against glutamate-induced elevation of occludin tyrosine phosphorylation. In addition, pretreatment with MK-801-attenuated glutamate-mediated disruption of endothelial barrier function. Blocking of the AMPA/KA receptors by 6,7-dinitroquinoxaline-2. 3-dione (DNQX) protected against hypophosphorylation of threonine residues of occludin; however, it did not affect disruption of endothelial integrity. These findings indicate the opposite effects of the NMDA and AMPA/KA receptors on occludin phosphorylation and disruption of the BBB functions.
A feedback transcriptional mechanism controls the level of the arginine/lysine transporter cat-1 during amino acid starvation
Authors: Lopez Alex B. , Wang Chuanping , Huang Charlie C. , Yaman Ibrahim , Li Yi , Chakravarty Kaushik , Johnson Peter F. , Chiang Cheng-Ming , Snider Martin D. , Wek Ronald C. , Hatzoglou Maria
Published: January 2007

The adaptive response to amino acid limitation in mammalian cells inhibits global protein synthesis and promotes the expression of proteins that protect cells from stress. The arginine/lysine transporter, cat-1, is induced during amino acid starvation by transcriptional and post-transcriptional mechanisms. It is shown in the present study that the transient induction of cat-1 transcription is regulated by the stress response pathway that involves phosphorylation of the translation initiation factor, eIF2 (eukaryotic initiation factor-2). This phosphorylation induces expression of the bZIP (basic leucine zipper protein) transcription factors C/EBP (CCAAT/enhancer-binding protein)-β and ATF (activating transcription factor) 4, which in turn induces ATF3. Transfection experiments in control and mutant cells, and chromatin immunoprecipitations showed that ATF4 activates, whereas ATF3 represses cat-1 transcription, via an AARE (amino acid response element), TGATGAAAC, in the first exon of the cat-1 gene, which functions both in the endogenous and in a heterologous promoter. ATF4 and C/EBPβ activated transcription when expressed in transfected cells and they bound as heterodimers to the AARE in vitro. The induction of transcription by ATF4 was inhibited by ATF3, which also bound to the AARE as a heterodimer with C/EBPβ. These results suggest that the transient increase in cat-1 transcription is due to transcriptional activation caused by ATF4 followed by transcriptional repression by ATF3 via a feedback mechanism.
Regulation of ceruloplasmin in human hepatic cells by redox active copper: identification of a novel AP-1 site in the ceruloplasmin gene
Authors: Das Dola , Tapryal Nisha , Goswami Shyamal K. , Fox Paul L. , Mukhopadhyay Chinmay K.
Published: January 2007

Cp (ceruloplasmin), a copper containing plasma protein, mainly synthesized in the liver, is known to be functional between the interface of iron and copper metabolism. We have reported previously that Cp is regulated by cellular iron status, but the process of the regulation of Cp by copper still remains a subject for investigation. In the present paper, we show that PDTC (pyrrolidine dithiocarbamate), a thiol compound widely known to increase intracellular redox copper, regulates Cp expression in hepatic cells by a copper-dependent transcriptional mechanism. To find out the mechanism of induction, chimeric constructs of the Cp 5′-flanking region driving luciferase were transfected into human hepatic cells. Deletion and mutational analyses showed the requirement of a novel APRE [AP-1 (activator protein-1) responsive element] present about 3.7 kb upstream of the translation initiation site. The role of AP-1 was confirmed by electrophoretic mobility-shift analysis. Western blot and overexpression studies detected the AP-1 as a heterodimer of c-jun and c-fos proteins. The activation of AP-1 was found to be copper-dependent as a specific extracellular chelator bathocuproine disulfonic acid blocked PDTC-mediated induction of AP-1–DNA binding and increased reporter gene activity. Whereas, in a copper-free medium, PDTC failed to activate either AP-1 or Cp synthesis, supplementation of copper could reverse AP-1 activation and Cp synthesis. Our finding is not only the first demonstration of regulation of Cp by redox copper but may also explain previous findings of increased Cp expression in cancers like hepatocarcinoma, where the intracellular copper level is higher in a redox compromised environment.
The role of neutral lipid nanospheres in Plasmodium falciparum haem crystallization
Authors: Pisciotta John M. , Coppens Isabelle , Tripathi Abhai K. , Scholl Peter F. , Shuman Joel , Bajad Sunil , Shulaev Vladimir , Sullivan David J.
Published: January 2007

The intraerythrocytic malaria parasite constructs an intracellular haem crystal, called haemozoin, within an acidic digestive vacuole where haemoglobin is degraded. Haem crystallization is the target of the widely used antimalarial quinoline drugs. The intracellular mechanism of molecular initiation of haem crystallization, whether by proteins, polar membrane lipids or by neutral lipids, has not been fully substantiated. In the present study, we show neutral lipid predominant nanospheres, which envelop haemozoin inside Plasmodium falciparum digestive vacuoles. Subcellular fractionation of parasite-derived haemozoin through a dense 1.7 M sucrose cushion identifies monoacylglycerol and diacylglycerol neutral lipids as well as some polar lipids in close association with the purified haemozoin. Global MS lipidomics detects monopalmitic glycerol and monostearic glycerol, but not mono-oleic glycerol, closely associated with haemozoin. The complex neutral lipid mixture rapidly initiates haem crystallization, with reversible pH-dependent quinoline inhibition associated with quinoline entry into the neutral lipid microenvironment. Neutral lipid nanospheres both enable haem crystallization in the presence of high globin concentrations and protect haem from H2O2 degradation. Conceptually, the present study shifts the intracellular microenvironment of haem crystallization and quinoline inhibition from a polar aqueous location to a non-polar neutral lipid nanosphere able to exclude water for efficient haem crystallization.
Identification of a novel targeting sequence for regulated secretion in the serine protease inhibitor neuroserpin
Authors: Ishigami Shoji , Sandkvist Maria , Tsui Foon , Moore Elizabeth , Coleman Timothy A. , Lawrence Daniel A.
Published: January 2007

Ns (neuroserpin) is a member of the serpin (serine protease inhibitor) gene family that is primarily expressed within the central nervous system. Its principal target protease is tPA (tissue plasminogen activator), which is thought to contribute to synaptic plasticity and to be secreted in a stimulus-dependent manner. In the present study, we demonstrate in primary neuronal cultures that Ns co-localizes in LDCVs (large dense core vesicles) with the regulated secretory protein chromogranin B. We also show that Ns secretion is regulated and can be specifically induced 4-fold by secretagogue treatment. A novel 13-amino-acid sorting signal located at the C-terminus of Ns is identified that is both necessary and sufficient to target Ns to the regulated secretion pathway. Its deletion renders Ns no longer responsive to secretagogue stimulation, whereas PAI-Ns [Ns (neuroserpin)–PAI-1 (plasminogen activator inhibitor-1) chimaera appending the last 13 residues of Ns sequence to the C-terminus of PAI-1] shifts PAI-1 secretion into a regulated secretory pathway.
The lipidation status of acute-phase protein serum amyloid A determines cholesterol mobilization via scavenger receptor class B, type I
Authors: Marsche Gunther , Frank Sǎsa , Raynes John G. , Kozarsky Karen F. , Sattler Wolfgang , Malle Ernst
Published: January 2007

During the acute-phase reaction, SAA (serum amyloid A) replaces apoA-I (apolipoprotein A-I) as the major HDL (high-density lipoprotein)-associated apolipoprotein. A remarkable portion of SAA exists in a lipid-free/lipid-poor form and promotes ABCA1 (ATP-binding cassette transporter A1)-dependent cellular cholesterol efflux. In contrast with lipid-free apoA-I and apoE, lipid-free SAA was recently reported to mobilize SR-BI (scavenger receptor class B, type I)-dependent cellular cholesterol efflux [Van der Westhuyzen, Cai, de Beer and de Beer (2005) J. Biol. Chem. 280, 35890–35895]. This unique property could strongly affect cellular cholesterol mobilization during inflammation. However, in the present study, we show that overexpression of SR-BI in HEK-293 cells (human embryonic kidney cells) (devoid of ABCA1) failed to mobilize cholesterol to lipid-free or lipid-poor SAA. Only reconstituted vesicles containing phospholipids and SAA promoted SR-BI-mediated cholesterol efflux. Cholesterol efflux from HEK-293 and HEK-293[SR-BI] cells to lipid-free and lipid-poor SAA was minimal, while efficient efflux was observed from fibroblasts and CHO cells (Chinese-hamster ovary cells) both expressing functional ABCA1. Overexpression of SR-BI in CHO cells strongly attenuated cholesterol efflux to lipid-free SAA even in the presence of an SR-BI-blocking IgG. This implies that SR-BI attenuates ABCA1-mediated cholesterol efflux in a way that is not dependent on SR-BI-mediated re-uptake of cholesterol. The present in vitro experiments demonstrate that the lipidation status of SAA is a critical factor governing cholesterol acceptor properties of this amphipathic apolipoprotein. In addition, we demonstrate that SAA mediates cellular cholesterol efflux via the ABCA1 and/or SR-BI pathway in a similar way to apoA-I.