bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of salts in the Hofmeister series and solvent isotopes on the gelation mechanisms for hydroxypropylmethylcellulose hydrogels
Authors: Liu S. Q. , Joshi Sunil C. , Lam Y. C.
Published: March 2008

The effects of various inorganic salts and isotopic solvents on the thermal gelation behavior of hydroxypropylmethylcellulose (HPMC) in aqueous solutions were examined by micro‐differential scanning calorimetry and rheological measurements. It was found that salting‐out salts, such as NaCl, promoted the sol–gel transition of HPMC at a lower temperature. An analysis of solvent isotope effects on the changes in the temperature at maximum heat capacity (Tm) with salt concentration showed that interchain hydrogen bonding (hydrogen bonding between the hydroxyl groups of different HPMC chains) was involved in the sol–gel transition, and its strength depended on the temperature and salt concentration. It was demonstrated that the effectiveness of anionic species in changing the Tm of the HPMC solutions was in the sequence of the Hofmeister series. Anionic species play a role in reducing Tm by their influence on the structure of the water, which in turn affects interactions between hydroxyl groups and water molecules, interchain hydrogen bonding, and the strength of the water cages prohibiting hydrophobic association. Rheological and microcalorimetric results indicated that the change in the thermodynamics of gelation of the HPMC aqueous solution was determined by the salt types and concentration, and the effect of monovalent salts was found to be more cooperative than that of multivalent salts on the sol–gel transition. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Production of fiber‐rich powder by the acid treatment of unripe banana flour
Authors: Aguirre‐Cruz A. , Álvarez‐Castillo A. , Yee‐Madeira H. , Bello‐Pérez L. A.
Published: March 2008

The acid treatment of unripe banana flour (UBF) was carried out to obtain a fiber‐rich product, and some functional and physicochemical characteristics were tested. An experimental design with temperature, time, and acid concentration as independent variables produced 20 experiments that were studied with a response surface methodology to discover the effect of these variables on the total dietary fiber (TDF) content. UBF showed a TDF content of 17% and a total starch content of 73%. The response surface regression model fitted to experimental results of TDF showed a good determination coefficient (94%). The maximum TDF content that predicted the model was 61.0% with conditions of 38°C, 11 days, and an acid concentration of 1.6M. During model validation for TDF, the model explained the experimental results to 99.5%. The thermal characterization of the fiber‐rich products after the acid treatment [acid‐treated unripe banana flour (ATUBF)] showed higher thermal stability than its parental sample. The water absorption index of ATUBF was lower but the water solubility of ATUBF was higher than its native counterpart. The preparation of a fiber‐rich product with UBF may be important for the development of food and medical products. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
The effect of pH on the polymer degradation and drug release from PLGA‐mPEG microparticles
Authors: Li Jin , Jiang Guoqiang , Ding Fuxin
Published: March 2008

In vitro drug release and degradation mechanism of Poly (dl‐lactide‐co‐glycolic acid)‐ methoxypoly (ethyleneglycol) (PLGA‐mPEG) microparticles were investigated under different pH conditions. Methotrexate(MTX), an antirheumatic drug, was employed as the model drug. In polyester‐based microparticle system, two main issues involved in degradation were water uptake and the carboxylic groups produced by chain scission. Polymer composition was identified to be responsible for the odd degradation behavior in different releasing media. Because of the exposure of mPEG chains at the particle surface, microparticle degradation showed apparent different mechanism under the investigated releasing conditions. At pH 10.08, microparticles exhibited rapid weight loss but slower molecular weight decrease, and the degradation pattern was close to surface degradation. At pH 7.4, microparticles underwent heterogeneous bulk degradation. However, at pH 1.2, it showed fastest molecular weight decrease while slowest weight loss, and homogeneous degradation was observed. Particle agglomeration was also seen in acidic environment. Fourier transform infrared (FTIR) spectrum results indicated the crystallization of drugs under the low pH condition. Drug release was dependent on transport paths and drug property. These two factors were highly controlled by the polymer degradation and drug solubility in the releasing media as well as drug crystallinity. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Poly(urethanes) containing silarylene and/or germarylene units
Authors: Terraza C. A. , Tagle L. H. , Leiva A. , Poblete L. , Concha F. J.
Published: March 2008

A series of 10 poly(urethanes) were synthesized by solution polymerization from bis(chloroformates) and aromatic diamines, containing both silicon or germanium as central atom. So, the polymers prepared contain two silicon atoms or two germanium atoms exclusively or combinations of both. Me, Et, and Ph groups were bonded to the central atoms according to the nature of the monomers employed. Poly(urethanes) were characterized by FTIR, 1H, 13C, and 29Si NMR spectroscopy and the results agreed with the proposed structures. Additionally, intrinsic viscosity values were established in DMSO solutions and thermal analyses were developed. In all cases, thermostable oligomers were obtained, which showed a degradation process beginning at ∼240–260°C. Polymers showed a thermal dependence with the nature of the heteroatom employed. Thus, in general, when germanium was used as central atom, the thermal stability was higher than the polymers containing silicon which agrees with the lower polarity and higher energy of the CGe bond in comparison with the CSi one. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008.
An exploration of affect factors and their role in user technology acceptance: Mediation and causality
Authors: Sun Heshan , Zhang Ping
Published: March 2008

Affect factors have gained researchers' attention in a number of fields. The Information Systems (IS) literature, however, shows some gaps and inconsistencies regarding the role of affect factors in human–computer interaction. Building upon prior research, this study aims at a better understanding of affect factors by clarifying their relationships with each other and with other primary user acceptance factors. Two affect variables that are different in nature were examined: computer playfulness (CP) and perceived enjoyment (PE). We theoretically clarified and methodologically verified their mediating effects and causal relationships with other primary factors influencing user technology acceptance, namely perceived ease of use (PEOU), perceived usefulness (PU), and behavioral intention (BI). Quantitative data were analyzed using R.M. Baron and D. Kenny's (1986) method for mediating effects and P.R. Cohen, A. Carlsson, L. Ballesteros, and R.S. Amant's (1993) path analysis method for causal relationships. These analyses largely supported our hypotheses. Results from this research indicate that a PE → PEOU causal direction is favored, and PEOU partially mediates PE's impacts on PU whereas PE fully mediates CP's impact on PEOU. With the increased interest in various affect factors in user technology acceptance and use, our study sheds light on the role of affect factors from both theoretical and methodological perspectives. Practical implications are discussed as well.
The molecular journey from ductal carcinoma in situ to invasive breast cancer
Authors: Wiechmann Lisa , Kuerer Henry M.
Published: March 2008

Ductal carcinoma in situ (DCIS) accounts for approximately 20% of mammographically detected breast cancers. DCIS can recur or progress to invasive breast cancer, but the ability to predict the outcome of patients with DCIS remains limited, leading to inappropriate treatment choices. To the authors' knowledge to date, the hunt for molecular prognostic markers for DCIS has been unsuccessful. Emerging technologies, however, are shedding new light on the biologic course of DCIS. In the current study, the authors review recent findings elucidating the molecular journey from DCIS to invasive cancer and discuss how these findings will lead to more effective treatment with minimization of morbidity. Cancer 2008. © 2008 American Cancer Society.
The association between extent of lymphadenectomy and survival among patients with lymph node metastases undergoing radical cystectomy
Authors: Wright Jonathan L. , Lin Daniel W. , Porter Michael P.
Published: March 2008

BACKGROUND.

Long‐term survival in patients with lymph node‐positive bladder cancer who undergo cystectomy suggests a therapeutic role for lymphadenectomy. The objective of this study was to describe the association between extent of lymphadenectomy and survival in lymph node‐positive patients who underwent radical cystectomy.

METHODS.

The cohort consisted of patients from the Surveillance, Epidemiology, and End Results registry with transitional cell carcinoma who underwent cystectomy with lymphadenectomy and had at least 1 positive lymph node and no distant metastases. The Kaplan‐Meier method and multivariate Cox proportional‐hazards regression analyses were used to estimate differences in survival among different lymphadenectomy variables.

RESULTS.

In total, 1260 patients had at least 1 positive lymph node. A median of 9 lymph nodes were removed (range, 1–48 lymph nodes) with a median of 2 positive lymph nodes (range, 1–18 positive lymph nodes), and the median lymph node density was 22%. In multivariate analysis controlling for patient demographics, tumor classification, and year of diagnosis, the number of positive and total lymph nodes removed remained independent predictors of survival. There was an inverse association between the number of lymph nodes removed and the risk of death for all quartiles. Removal of > 10 lymph nodes was associated with increased overall survival (hazard ratio, 0.52; 95% confidence interval, 0.43–0.64). In addition, with a lymph node density from 0.1% to 12.5% as the referent group, each higher quartile experienced worse survival.

CONCLUSIONS.

An increased number of lymph nodes removed at the time of cystectomy was associated with improved survival in patients with lymph node‐positive bladder cancer. Improved survival was observed at a lower lymph node density threshold than previously reported. The current findings support performing a more extensive lymphadenectomy at the time of cystectomy. Cancer 2008. © 2008 American Cancer Society.
Rapid activity‐dependent delivery of the neurotrophic protein CPG15 to the axon surface of neurons in intact Xenopus tadpoles
Authors: Cantallops Isabel , Cline Hollis T.
Published: March 2008

CPG15 (aka neuritin) is an activity‐induced GPI‐anchored axonal protein that promotes dendritic and axonal growth, and accelerates synaptic maturation in vivo. Here we show that CPG15 is distributed inside axons and on the axon surface. CPG15 is trafficked to and from the axonal surface by membrane depolarization. To assess CPG15 trafficking in vivo, we expressed an ecliptic pHluorin (EP)‐CPG15 fusion protein in optic tectal explants and in retinal ganglion cells of intact Xenopus tadpoles. Depolarization by KCl increased EP‐CPG15 fluorescence on axons. Intraocular kainic acid (KA) injection rapidly increased cell‐surface EP‐CPG15 in retinotectal axons, but coinjection of TTX and KA did not. Consistent with this, we find that intracellular CPG15 is localized to vesicles and endosomes in presynaptic terminals and colocalizes with synaptic vesicle proteins. The results indicate that the delivery of the neurotrophic protein CPG15 to the axon surface can be regulated on a rapid time scale by activity‐dependent mechanisms in vivo. © 2008 Wiley Periodicals, Inc. Develop Neurobiol, 2008
The adolescent brain: Insights from functional neuroimaging research
Authors: Ernst Monique , Mueller Sven C.
Published: March 2008

With the development of functional neuroimaging tools, the past two decades have witnessed an explosion of work examining functional brain maps, mostly in the adult brain. Against this backdrop of work in adults, developmental research begins to gather a substantial body of knowledge about brain maturation. The purpose of this review is to present some of these findings from the perspective of functional neuroimaging. First, a brief survey of available neuroimaging techniques (i.e., fMRI, MRS, MEG, PET, SPECT, and infrared techniques) is provided. Next, the key cognitive, emotional, and social changes taking place during adolescence are outlined. The third section gives examples of how these behavioral changes can be understood from a neuroscience perspective. The conclusion places this functional neuroimaging research in relation to clinical and molecular work, and shows how answers will ultimately come from the combined efforts of these disciplines. © 2008 Wiley Periodicals, Inc. Develop Neurobiol, 2008
Using imaging and genetics in zebrafish to study developing spinal circuits in vivo
Authors: McLean David L. , Fetcho Joseph R.
Published: March 2008

Imaging and molecular approaches are perfectly suited to young, transparent zebrafish (Danio rerio), where they have allowed novel functional studies of neural circuits and their links to behavior. Here, we review cutting‐edge optical and genetic techniques used to dissect neural circuits in vivo and discuss their application to future studies of developing spinal circuits using living zebrafish. We anticipate that these experiments will reveal general principles governing the assembly of neural circuits that control movements. © 2008 Wiley Periodicals, Inc. Develop Neurobiol, 2008
Imaging the spatiotemporal organization of neural activity in the developing spinal cord
Authors: O'Donovan Michael J. , Bonnot Agnes , Mentis George Z. , Arai Yoshi , Chub Nikolai , Shneider Neil A. , Wenner Peter
Published: March 2008

In this review, we discuss the use of imaging to visualize the spatiotemporal organization of network activity in the developing spinal cord of the chick embryo and the neonatal mouse. We describe several different methods for loading ion‐ and voltage‐sensitive dyes into spinal neurons and consider the advantages and limitations of each one. We review work in the chick embryo, suggesting that motoneurons play a critical role in the initiation of each cycle of spontaneous network activity and describe how imaging has been used to identify a class of spinal interneuron that appears to be the avian homolog of mammalian Renshaw cells or 1a‐inhibitory interneurons. Imaging of locomotor‐like activity in the neonatal mouse revealed a wave‐like activation of motoneurons during each cycle of discharge. We discuss the significance of this finding and its implications for understanding how locomotor‐like activity is coordinated across different segments of the cord. In the last part of the review, we discuss some of the exciting new prospects for the future. © 2008 Wiley Periodicals, Inc. Develop Neurobiol, 2008
In vivo imaging of presynaptic terminals and postsynaptic sites in the mouse submandibular ganglion
Authors: McCann Corey M. , Lichtman Jeff W.
Published: March 2008

Much of what is currently known about the behavior of synapses in vivo has been learned at the mammalian neuromuscular junction, because it is large and accessible and also its postsynaptic acetylcholine receptors (AChRs) are readily labeled with a specific, high‐affinity probe, α‐bungarotoxin (BTX). Neuron–neuron synapses have thus far been much less accessible. We therefore developed techniques for imaging interneuronal synapses in an accessible ganglion in the peripheral nervous system. In the submandibular ganglion, individual preganglionic axons establish large numbers of axo‐somatic synapses with postganglionic neurons. To visualize these sites of synaptic contact, presynaptic axons were imaged by using transgenic mice that express fluorescent protein in preganglionic neurons. The postsynaptic sites were visualized by labeling the acetylcholine receptor (AChR) α7 subunit with fluorescently tagged BTX. We developed in vivo methods to acquire three‐dimensional image stacks of the axons and postsynaptic sites and then follow them over time. The submandibular ganglion is an ideal site to study the formation, elimination, and maintenance of synaptic connections between neurons in vivo. © 2008 Wiley Periodicals, Inc. Develop Neurobiol, 2008
Management of sinonasal undifferentiated carcinoma
Authors: Tanzler Emily D. , Morris Christopher G. , Orlando Christine A. , Werning John W. , Mendenhall William M.
Published: March 2008

Background.

Our aim was to report the outcomes of treatment for sinonasal undifferentiated carcinoma (SNUC).

Methods.

Between September 1992 and October 2005, 15 patients were treated with curative intent with surgery (n = 1), surgery and adjuvant radiotherapy (n = 9), and definitive radiotherapy (RT) (n = 5). Follow‐up ranged from 11 to 151 months (median, 30); follow‐up on living patients ranged from 12 to 151 months (median, 22). No patient was lost to follow‐up.

Results.

Seven patients (47%) developed a recurrence from 3 to 50 months (median, 9) after treatment. The 3‐year outcomes were: local control, 78%; locoregional control, 65%; distant metastasis–free survival, 82%; cause‐specific survival, 77%, and survival, 67%. The local control rates versus treatment modality were: surgery, 0/1 (0%); surgery and postoperative RT, 7/7 (100%); preoperative RT and surgery, 2/2 (100%); and definitive RT, 2/5 (40%). One patient (7%) treated with surgery and postoperative RT sustained a fatal complication.

Conclusions.

Combined surgery and adjuvant RT likely offer the best chance of cure compared with either modality alone. The impact of adjuvant chemotherapy is unclear. © 2008 Wiley Periodicals, Inc. Head Neck, 2008
Functional reconstruction of complex lip and cheek defect with free composite anterolateral thigh flap and vascularized fascia
Authors: Kuo Yur‐Ren , Jeng Seng‐Feng , Wei Fu‐Chan , Su Chih‐Ying , Chien Chih‐Yen
Published: March 2008

Background.

Extensive composite defects involving the lip and cheek present difficult reconstructive challenges. This study presents a technique using anterolateral thigh (ALT) flaps with vascularized fascia for large complex oral sphincter defect reconstruction.

Methods.

Fifteen patients who had undergone oral cancer ablation were enrolled in the study. The average area of intraoral lining and cheek–lip skin defects was 96.9 cm2. Upper‐lip defects ranged 0% to 60%, and lower‐lip defects ranged 20% to 80%. Skin and intraoral lining defects were replaced by an ALT fasciacutaneous flap. The vascularized fascia of the flap was used to provide lip suspension.

Results.

Flap survival was 100%. All but 1 patient had good static suspension. Nine patients had adequate oral competence without drooling, but 6 had occasional oral incontinence. All patients achieved an acceptable appearance.

Conclusions.

For extensive cheek–lip composite defects, ALT flap together with vascularized fascia has proven to be a useful option for functional reconstruction. © 2008 Wiley Periodicals, Inc. Head Neck 2008
Emerging perspectives in epidermal growth factor receptor targeting in head and neck cancer
Authors: Kim Seungwon , Grandis Jennifer R. , Rinaldo Alessandra , Takes Robert P. , Ferlito Alfio
Published: March 2008

The epidermal growth factor receptor (EGFR) has been shown to be a promising therapeutic target in head and neck cancer. Cetuximab, a monoclonal antibody against EGFR, has been approved in the United States for use with radiotherapy for head and neck squamous cell carcinoma. However, the role of EGFR targeting agents in other therapeutic modalities, such as combined chemoradiotherapy or induction chemotherapy, remains to be defined. Although results from several clinical trials have demonstrated the therapeutic potentials of EGFR targeting agents in these settings, further studies are necessary before definitive conclusions can be made. The concurrent targeting of EGFR along with other pathways important in carcinogenesis may hold significant therapeutic potential. In particular, several clinical trials are studying the effects of combining agents that target the vascular endothelial growth factor with EGFR inhibitors. Last, studies are ongoing to elucidate the predictive and correlative biomarkers in anti‐EGFR therapy to allow for proper patient selection. In the case of cetuximab, these correlative biomarkers may include elements of the immune system in addition to the signal transduction proteins involved in EGFR pathway. © 2008 Wiley Periodicals, Inc. Head Neck, 2008
A conjecture of Borodin and a coloring of Grünbaum
Authors: Rautenbach Dieter
Published: March 2008

In 1976, Borodin conjectured that every planar graph has a 5‐coloring such that the union of every k color classes with 1 ≤ k ≤ 4 induces a (k—1)‐degenerate graph. We prove the existence of such a coloring using 18 colors. © 2008 Wiley Periodicals, Inc. J Graph Theory 58:139–147, 2008
An improved bound for the strong chromatic number
Authors: Haxell P. E.
Published: March 2008

Let η > 0 be given. Then there exists d0 = d0(η) such that the following holds. Let G be a finite graph with maximum degree at most d ≥ d0 whose vertex set is partitioned into classes of size α d, where α≥ 11/4 + η. Then there exists a proper coloring of G with αd colors in which each class receives all αd colors. © 2008 Wiley Periodicals, Inc. J Graph Theory 58:148–158, 2008
The black stuff and Konstantin Nikolaevich Tretiakoff
Authors: Lees Andrew J. , Selikhova Marianna , Andrade Luiz Augusto , Duyckaerts Charles
Published: March 2008

Konstantin Tretiakoff's doctoral dissertation “Contribution a l'Etude de L'Anatomie pathologique du Locus Niger de Soemmering avec quelques déductions relatives à la pathogénie des troubles du tonus musculaire et De La Maladie de Parkinson” (A Study of the Pathological anatomy of the locus niger of Soemerring and its relevance to the pathogenesis of changes in muscular tone in Parkinson's disease) published in 1919 earned him a silver medal awarded by the University of Paris but failed to gain him the recognition its importance deserved. Despite belated acknowledgment of the importance of his findings Tretiakoff received little acclaim during his life and there have been no biographical accounts written in English or French. Fifty years after his death it seems appropriate to relate some aspects of his interesting peripatetic life and recognize the continuing relevance of his pioneering research on “the black stuff” to our understanding of Parkinson's disease. © 2008 Movement Disorder Society
Oculomotor function in multiple system atrophy: Clinical and laboratory features in 30 patients
Authors: Anderson Tim , Luxon Linda , Quinn Niall , Daniel Susan , David Marsden C. , Bronstein Adolfo
Published: March 2008

We reviewed the clinical and laboratory oculomotor features in 30 patients with probable multiple system atrophy (MSA), 22 with MSA‐P and 8 with MSA‐C. Six patients were also examined post mortem, MSA being confirmed in four and excluded in two (Parkinson's disease and progressive supranuclear palsy). Clinical examination showed the following abnormalities; excessive square wave jerks—21 of 30 patients; mild vertical supranuclear gaze palsy—8 of 30; gaze‐evoked nystagmus—12 of 30 patients, three of whom had no extraocular evidence of cerebellar dysfunction; positioning downbeat nystagmus—10 of 25; mild or moderate saccadic hypometria—22 of 30; impaired (“broken up”) smooth pursuit—28 of 30; reduced VOR suppression—16 of 24. Electro‐oculography and caloric testing did not add significant extra information. In patients presenting with an akinetic‐rigid syndrome it can be difficult to differentiate idiopathic Parkinson's disease from MSA‐P and other causes of atypical parkinsonism. Our findings suggest that the presence of excessive square wave jerks, mild – moderate hypometria of saccades, impaired VOR suppression, spontaneous nystagmus or positioning downbeat nystagmus may be oculomotor “red flags” or clues to the presence of MSA. Further, the presence of clinically slow saccades, or moderate‐to‐severe gaze restriction, suggests a diagnosis other than MSA. © 2008 Movement Disorder Society
Neuronal activity of the red nucleus in Parkinson's disease
Authors: Rodriguez‐Oroz María C. , Rodriguez Manolo , Leiva Carlos , Rodriguez‐Palmero Miguel , Nieto Juan , Garcia‐Garcia David , Luis Zubieta Jose , Cardiel Carlos , Obeso Jose A.
Published: March 2008

Precise placement of the electrodes for stimulation of the subthalamic nucleus (STN) in Parkinson's disease (PD) is crucial for the therapeutic benefit. As a result of the mistargeting and misplacement of the electrodes during surgery in 2 patients with PD, we have characterized the neuronal firing in the red nucleus (RN) and observed the effects of stimulation of this nucleus. Although the neuronal firing (mean ± SD) of the RN (34 ± 4.4 Hz) resembles that described for the STN (33.1 ± 16.6 Hz), a higher proportion of cells responded to the movement of the contralateral limbs (70–80%). Stimulation in the area of the RN‐induced intolerable side effects without motor improvement. We conclude that the STN and RN have some similar neurophysiological features but can be distinguished intraoperatively. This initial description of the physiological characteristics of the RN in humans will draw attention to the possibility of confusing the RN and STN during intraoperative recording. © 2008 Movement Disorder Society
Scaling turbulent atmospheric stratification. II: Spatial stratification and intermittency from lidar data
Authors: Lilley M. , Lovejoy S. , Strawbridge K. B. , Schertzer D. , Radkevich A.
Published: March 2008

We critically re‐examine existing empirical studies of vertical and horizontal statistics of the horizontal wind and find that the balance of evidence is in favour of the Kolmogorov kx−5/3 scaling in the horizontal, Bolgiano‐Obukov scaling kz−11/5 in the vertical corresponding to a Ds = 23/9 stratified atmosphere in (x, y, z) space. This interpretation is particularly compelling once one recognizes that the 23/9‐D turbulence can lead to long‐range biases in aircraft trajectories and hence to spurious statistical exponents in wind, temperature and other statistics reported in the literature. Indeed, we show quantitatively that one is easily able to reinterpret the major aircraft‐based campaigns (GASP, MOZAIC) in terms of the model. In part I, we have seen that this model is compatible with ‘turbulence waves’ which can be close to classical linear gravity waves in spite of their very different nonlinear mechanism. We then use state‐of‐the‐art lidar data of atmospheric aerosols (considered as passive tracers) in order to obtain direct estimates of the effective (‘elliptical’) dimension of the spatial part: Ds = 23/9 = 2.55 ± 0.02. This result essentially rules out the standard 3‐D or 2‐D isotropic theories or the anisotropic quasi‐linear gravity wave theories which have Ds = 3, 2, 7/3 respectively.

In this paper we focus on the multifractal (intermittency) statistics showing that there is a very small but apparently real variation in the value of Ds, ranging for the weak and intense structures so that Ds ranges from roughly 2.53 to 2.57. We also show that the passive scalars are well approximated by universal multifractals; we estimate the exponents to be αh = 1.82 ± 0.05, αv = 1.83 ± 0.04, C1h = 0.037 ± 0.0061 and C1v = 0.059 ± 0.007 (h for horizontal, v for vertical). Copyright © 2008 Royal Meteorological Society
Altered pain processing in children with migraine: An evoked potential study
Authors: Zohsel Katrin , Hohmeister Johanna , Flor Herta , Hermann Christiane
Published: March 2008

In adults, evidence is accumulating that migraine is associated with altered central processing of pain stimuli and, possibly, changes in the allocation of attentional resources to such stimuli. In pediatric migraine, however, little is known about altered pain processing. We examined 15 children with migraine and 15 controls (age 10–15) in an oddball standards task. Children had to respond to rare targets (tones) and ignore frequent painful (pain threshold) or non‐painful mechanical standard stimuli while evoked potentials were obtained. Painful as compared to non‐painful stimuli elicited significantly larger N150, P260 and P300 components of the somatosensory evoked potential in all children. The pain‐evoked N150 and P260 components did not differ significantly between groups. However, in children with migraine, both painful and non‐painful standard stimuli were associated with significantly larger P300 amplitudes at significantly shorter latencies. Perceived intensity of the painful and non‐painful stimuli was comparable in both groups. The evoked potentials and reaction times to the target tones did not differ significantly between groups. Habituation across trials was similar in both groups. Hence, children with migraine may display an automatic attentional bias towards painful and potentially painful somatosensory stimuli. Consistent with the psychobiological perspective of chronic pain, such an attentional bias could constitute an important mechanism for migraine becoming a chronic problem.
SNAP‐25 is also an iron–sulfur protein
Authors: Huang Qingqiu , Hong Xinguo , Hao Quan
Published: March 2008

SNAP‐25 has a cysteine cluster located at its linker domain. In vivo, the cysteine residues in this cluster can be palmitoylated, and the hydrophobic palmitate molecules can target SNAP‐25 to the presynaptic membrane. Here, we report that the SNAP‐25a expressed in Escherichia coli is also an iron–sulfur protein binding an iron–sulfur cluster using the cysteine residues in its cysteine cluster. Therefore, SNAP‐25a uses the same cysteine residues to bind two different prosthetic groups (iron–sulfur cluster and palmitate). Because the binding sites of these two prosthetic groups overlap, we suggest that these two modifications occur at different times, and probably at different places in the cell.
The Ecological implications of a Yakutian mammoth's last meal
Authors: van Geel Bas , Aptroot André , Baittinger Claudia , Birks Hilary H. , Bull Ian D. , Cross Hugh B. , Evershed Richard P. , Gravendeel Barbara , Kompanje Erwin J.O. , Kuperus Peter , Mol Dick , Nierop Klaas G.J. , Pals Jan Peter , Tikhonov Alexei N. , van Reenen Guido , van Tienderen Peter H.
Published: March 2008

Part of a large male woolly mammoth (Mammuthus primigenius) was preserved in permafrost in northern Yakutia. It was radiocarbon dated to ca. 18,50014C yr BP (ca. 22,500 cal yr BP). Dung from the lower intestine was subjected to a multiproxy array of microscopic, chemical, and molecular techniques to reconstruct the diet, the season of death, and the paleoenvironment. Pollen and plant macro-remains showed that grasses and sedges were the main food, with considerable amounts of dwarf willow twigs and a variety of herbs and mosses. Analyses of 110-bp fragments of the plastid rbcL gene amplified from DNA and of organic compounds supplemented the microscopic identifications. Fruit-bodies of dung-inhabiting Ascomycete fungi which develop after at least one week of exposure to air were found inside the intestine. Therefore the mammoth had eaten dung. It was probably mammoth dung as no bile acids were detected among the fecal biomarkers analysed. The plant assemblage and the presence of the first spring vessels of terminal tree-rings of dwarf willows indicated that the animal died in early spring. The mammoth lived in extensive cold treeless grassland vegetation interspersed with wetter, more productive meadows. The study demonstrated the paleoecological potential of several biochemical analytical techniques.
The stability of wave‐driven rip current circulation
Authors: Kennedy A. B. , Zhang Y.
Published: March 2008

This paper examines the stability of rip currents with shore‐normal wave forcing using numerical stability analyses of nonlinear base flows. Leading order diffraction and wave‐current interaction effects are included, and the effects of depth‐varying currents are also treated in a parameterized manner. Stable and unstable eigenmodes are identified with a variety of forms. For rip currents with strength of O(0.5 m/s), instabilities are seen with a family resemblance to oscillating sinuous jets, as well as more complex forms. For low strength rip currents of O(0.3 m/s), these modes stabilize but are replaced by sinuous and varicose instabilities that extend far offshore and are believed to be convective instabilities made absolutely unstable through wave‐current interaction. Quantitative values for growth rates are found to be strongly dependent on details of the velocity field and on the coefficient of bottom friction. Peak vorticity was found to be a good predictor of oscillation periods for unstable jet modes.
Bundled turbidite deposition in the central Pandora Trough (Gulf of Papua) since Last Glacial Maximum: Linking sediment nature and accumulation to sea level fluctuations at millennial timescale
Authors: Jorry Stéphan J. , Droxler André W. , Mallarino Gianni , Dickens Gerald R. , Bentley Sam J. , Beaufort Luc , Peterson Larry C. , Opdyke Bradley N.
Published: March 2008

Since Last Glacial Maximum (23–19 ka), Earth climate warming and deglaciation occurred in two major steps (Bølling‐Allerød and Preboreal), interrupted by a short cooling interval referred to as the Younger Dryas (12.5–11.5 ka B.P.). In this study, three cores (MV‐33, MV‐66, and MD‐40) collected in the central part of Pandora Trough (Gulf of Papua) have been analyzed, and they reveal a detailed sedimentary pattern at millennial timescale. Siliciclastic turbidites disappeared during the Bølling‐Allerød and Preboreal intervals to systematically reoccur during the Younger Dryas interval. Subsequent to the final disappearance of the siliciclastic turbidites a calciturbidite occurred during meltwater pulse 1B. The Holocene interval was characterized by a lack of siliciclastic turbidites, relatively high carbonate content, and fine bank‐derived aragonitic sediment. The observed millennial timescale sedimentary variability can be explained by sea level fluctuations. During the Last Glacial Maximum, siliciclastic turbidites were numerous when the lowstand coastal system was located along the modern shelf edge. Although they did not occur during the intervals of maximum flooding of the shelf (during meltwater pulses 1A and 1B), siliciclastic turbidites reappear briefly during the Younger Dryas, an interval when sea level rise slowed, stopped, or perhaps even fell. The timing of the calciturbidite coincides with the first reflooding of Eastern Fields Reef, an atoll that remained exposed for most of the glacial stages.
Successful prediction of the consecutive IOD in 2006 and 2007
Authors: Luo Jing‐Jia , Behera Swadhin , Masumoto Yukio , Sakuma Hirofumi , Yamagata Toshio
Published: March 2008

During 2006 and 2007 boreal fall, two consecutive positive Indian Ocean Dipole (pIOD) events occurred unprecedentedly regardless of the respective El Niño and La Niña condition in the Pacific. These two pIOD events had large climate impacts, particularly in the Eastern Hemisphere. Experimental forecasts using a coupled model show that the two pIOD events can be predicted 3 or 4 seasons ahead. The evolution of the 2006 pIOD is consistent with the large‐scale IOD dynamics, and therefore, it has long‐lead predictability owing to the oceanic subsurface memory in the South Indian Ocean. The 2007 pIOD event, however, is rather weak and peculiar without a long memory from the off‐equatorial ocean. The model has less predictability for this weak event. The results show that seasonal climate anomalies in the Eastern Hemisphere associated with the two pIOD events can be predicted 1–2 seasons ahead. This indicates potential societal benefits of IOD prediction.
Contribution of particle formation to global cloud condensation nuclei concentrations
Authors: Spracklen Dominick V. , Carslaw Kenneth S. , Kulmala Markku , Kerminen Veli‐Matti , Sihto Sanna‐Liisa , Riipinen Ilona , Merikanto Joonas , Mann Graham W. , Chipperfield Martyn P. , Wiedensohler Alfred , Birmili Wolfram , Lihavainen Heikki
Published: March 2008

We use a global aerosol microphysics model to predict the contribution of boundary layer (BL) particle formation to regional and global distributions of cloud condensation nuclei (CCN). Including an observationally derived particle formation scheme, where the formation rate of molecular clusters is proportional to gas‐phase sulfuric acid to the power one, improves modeled particle size distribution and total particle number concentration at three continental sites in Europe. Particle formation increases springtime BL global mean CCN (0.2% supersaturation) concentrations by 3–20% and CCN (1%) by 5–50%. Uncertainties in particle formation and growth rates must be reduced before the accuracy of these predictions can be improved. These results demonstrate the potential importance of BL particle formation as a global source of CCN.
Terrestrial and marine POC fluxes derived from 234Th distributions and δ13C measurements on the Mackenzie Shelf
Authors: Amiel David , Cochran J. Kirk
Published: March 2008

Water column deficits of 234Th relative to 238U in the Mackenzie Shelf, Cape Bathurst Polynya, and Amundsen Gulf were used to estimate sinking fluxes of particulate organic carbon (POC) in these areas. The 234Th fluxes were converted to marine and terrestrial POC fluxes using the POC/Th ratio on filterable particles >70 μm and δ13C measurements to determine the fraction of marine and terrestrial POC. In June/July 2004, the greatest 234Th deficits (0–100 m: 56–95 dpm m−2) were observed in the Mackenzie outer shelf. Deficits in the upper 100 m ranged from 3 to 59 dpm m−2 in the Cape Bathurst Polynya. The δ13C values of POC in the >70‐μm particles filtered in situ pumps ranged from −25.1‰ to −28‰. Using a two‐end‐member mixing model with marine POC = −21.4‰ and terrestrial POC = −28‰ shows that terrestrial POC is most evident at the Mackenzie Shelf stations but is present throughout the region. The fraction of marine POC ranged from 0 to 59% in the area in June/July 2004, with highest values in the Cape Bathurst Polynya. Fluxes of marine POC in the polynya average ∼5 mmol C m−2 d−1 at 50 m in June 2004 and increase to ∼12 mmol C m−2 d−1 in July. Comparable fluxes are observed at 100 m in June, but values decrease to ∼6 mmol C m−2 d−1 at 100 m in July. These fluxes are greater than estimates of organic carbon remineralization and burial in sediments of the polynya (∼3 mmol m−2 d−1), suggesting that POC may be exported out of the area, effectively remineralized by microbial activity in the twilight zone or incorporated into biomass.
The mean seasonal cycle in sea level estimated from a data‐constrained general circulation model
Authors: Vinogradov Sergey V. , Ponte Rui M. , Heimbach Patrick , Wunsch Carl
Published: March 2008

A near‐global ocean state estimate over the period 1992–2004 is used to study the mean seasonal cycle in sea level ζ. The state estimate combines most available observations, including all the altimetric missions, with a general circulation model in an optimization procedure. The annual cycle tends to be larger than the semi‐annual one, except in tropical regions. For global mean ζ, annual thermosteric and freshwater terms are nearly out‐of‐phase and lead to an annual cycle of only a few mm in amplitude. Regionally, surface wind stress and heat flux are the primary drivers for seasonal ζ variations in the tropics and midlatitudes, respectively, with both mechanisms playing a role at high latitudes. A substantial part of the annual ζ variability can be assigned to changes in thermosteric height in the upper 100 m in midlatitudes and 200 m in the tropics. Bottom pressure variability is larger at high latitudes, and also in some regions in the Southern Ocean and North Pacific. Apparent nonlinear rectification processes lead to a noticeable impact of submonthly forcing on the annual cycle in the western North Atlantic and North Pacific. Other features include the substantial ζ gradients associated with strong spatial variability in seasonal surface heat flux in some western boundary regions, the damping effects of surface heat flux on the seasonal cycle in the tropics, and the importance of wind driving and bottom pressure in shallow regions, which can cause differences in the seasonal cycle in some coastal and contiguous deep‐ocean regions.
Impact of land use and precipitation changes on surface temperature trends in Argentina
Authors: Nuñez Mario N. , Ciapessoni Héctor H. , Rolla Alfredo , Kalnay Eugenia , Cai Ming
Published: March 2008

The “observation minus reanalysis” (OMR) method has been used to estimate the impact of changes in land use (including urbanization and agricultural practices such as irrigation) by computing the difference between the trends of the surface observations (which reflect all the sources of climate forcing, including surface effects) and the NCEP/NCAR reanalysis (which only contains the forcings influencing the assimilated atmospheric trends). In this paper we apply the OMR method to surface stations in Argentina for the period 1961–2000. In contrast to most other land areas, over most of Argentina there has been net cooling, not warming (about −0.04°C/decade). Observations also show a very strong decrease in the diurnal temperature range north of 40°S. This is associated with an observed strong reduction in the maximum temperature (−0.12°C/decade) together with a weak warming trend in the minimum temperature (0.05°C/decade). The OMR trends show a warming contribution to the mean temperature (+0.07°C/decade) and a decrease in diurnal temperature range (−0.08°C/decade), especially strong in the areas where the observed precipitation has increased the most and where, as a consequence, there has been an exponential increase of soy production in the last decade. The increase in precipitation is apparently associated with an increase in the moisture transport from the Amazons to northern Argentina by the low‐level jet.
Spatial variation in the influence of the North Atlantic Oscillation on precipitation across Greenland
Authors: Calder Catherine A. , Craigmile Peter F. , Mosley‐Thompson Ellen
Published: March 2008

Ice core‐derived accumulation records from Greenland have been proposed as proxies for North Atlantic Oscillation (NAO) reconstruction. In a series of single‐site analyses, accumulation records from ice cores drilled in western Greenland were found to exhibit the strongest linear association with NAO. In this paper, we expand on these findings by proposing a spatiotemporal statistical model to explore further the relationship between NAO and the accumulation records from 35 firn and ice cores drilled in western and southern Greenland. In particular, we propose a temporal extension of the Bayesian spatially varying coefficient regression model, which is fit using a Markov chain Monte Carlo algorithm. This model readily accommodates the irregular features of the data (i.e., variation in record lengths and irregular spacing among ice core locations) and the serial dependence within individual records. Using our statistical model, we are able to exploit the spatial dependence structure of the derived accumulation‐NAO relationship to explore the regional patterns in the strength of this relationship. Our findings support previous work that identified a region in western Greenland where derived accumulation is most correlated with NAO. However, we also identify a region further inland to the east and south where the estimated strength of the linear accumulation‐NAO relationship is weaker, but more certain, than in the previously identified region. Thus, our findings can be used to guide decisions regarding where to locate future drilling efforts in Greenland by weighing the trade‐off between the potential strength of the accumulation‐NAO relationship and its uncertainty.
Deglacial variability in the surface return flow of the Atlantic meridional overturning circulation
Authors: Came Rosemarie E. , Oppo Delia W. , Curry William B. , Lynch‐Stieglitz Jean
Published: March 2008

Benthic foraminiferal Cd/Ca from a Florida Current sediment core documents the history of the northward penetration of southern source waters within the surface return flow of the Atlantic meridional overturning circulation (AMOC). Cd seawater estimates (CdW) indicate that intermediate‐depth southern source waters crossed the equator and contributed to the Florida Current during the Bølling‐Allerød warm period of the last deglaciation, consistent with evidence of only a modest AMOC reduction compared to today. The CdW estimates also provide the first paleoceanographic evidence of a reduction in the influence of intermediate‐depth southern source waters within the Florida Current during the Younger Dryas, a deglacial cold event characterized by a weak North Atlantic AMOC. Our results reveal a close correspondence between the northward penetration of intermediate‐depth southern source waters and the influence of North Atlantic Deep Water, suggesting a possible link between intermediate‐depth southern source waters and the strength of the Atlantic AMOC.
Effects of turbulence on hydraulic heads and parameter sensitivities in preferential groundwater flow layers
Authors: Shoemaker W. Barclay , Cunningham Kevin J. , Kuniansky Eve L. , Dixon Joann
Published: March 2008

A conduit flow process (CFP) for the Modular Finite Difference Ground‐Water Flow model, MODFLOW‐2005, has been created by the U.S. Geological Survey. An application of the CFP on a carbonate aquifer in southern Florida is described; this application examines (1) the potential for turbulent groundwater flow and (2) the effects of turbulent flow on hydraulic heads and parameter sensitivities. Turbulent flow components were spatially extensive in preferential groundwater flow layers, with horizontal hydraulic conductivities of about 5,000,000 m d−1, mean void diameters equal to about 3.5 cm, groundwater temperature equal to about 25°C, and critical Reynolds numbers less than or equal to 400. Turbulence either increased or decreased simulated heads from their laminar elevations. Specifically, head differences from laminar elevations ranged from about −18 to +27 cm and were explained by the magnitude of net flow to the finite difference model cell. Turbulence also affected the sensitivities of model parameters. Specifically, the composite‐scaled sensitivities of horizontal hydraulic conductivities decreased by as much as 70% when turbulence was essentially removed. These hydraulic head and sensitivity differences due to turbulent groundwater flow highlight potential errors in models based on the equivalent porous media assumption, which assumes laminar flow in uniformly distributed void spaces.
When will Lake Mead go dry?
Authors: Barnett Tim P. , Pierce David W.
Published: March 2008

A water budget analysis shows that under current conditions there is a 10% chance that live storage in Lakes Mead and Powell will be gone by about 2013 and a 50% chance that it will be gone by 2021 if no changes in water allocation from the Colorado River system are made. This startling result is driven by climate change associated with global warming, the effects of natural climate variability, and the current operating status of the reservoir system. Minimum power pool levels in both Lake Mead and Lake Powell will be reached under current conditions by 2017 with 50% probability. While these dates are subject to some uncertainty, they all point to a major and immediate water supply problem on the Colorado system. The solutions to this water shortage problem must be time‐dependent to match the time‐varying, human‐induced decreases in future river flow.