bluuebunny/crossref_metadata_2025 huggingface dataset:
Nanotechnology in the design of soft tissue scaffolds: innovations in structure and function
Authors: Ayres Chantal E. , Jha B. Shekhar , Sell Scott A. , Bowlin Gary L. , Simpson David G.
Published: October 2009

Engineered scaffolds function to supplement or replace injured, missing, or compromised tissue or organs. The current direction in this research area is to create scaffolds that mimic the structure and function of the native extracellular matrix (ECM). It is believed that the fabrication of a scaffold that has both structural integrity and allows for normal cellular function and interaction will bring scaffolds closer to clinical relevance. Nanotechnology innovations have aided in the development of techniques for the production of nanofiber scaffolds. The three major processing techniques, self‐assembly, phase separation, and electrospinning, produce fibers that rival the size of those found in the native ECM. However, the simplicity, versatility, and scalability of electrospinning make it an attractive processing method that can be used to reproduce aspects of the complexity that characterizes the native ECM. Novel electrospinning strategies include alterations of scaffold composition and architecture, along with the addition and encapsulation of cells, pharmaceuticals and growth factors within the scaffold. This article reviews the major nanofiber fabrication technologies as well as delves into recent significant contributions to the conception of a meaningful and practical electrospun scaffold. WIREs Nanomed Nanobiotechnol 2010 2 20–34

This article is categorized under:

Implantable Materials and Surgical Technologies > Nanotechnology in Tissue Repair and Replacement
Probing dynamic fluorescence properties of single and clustered quantum dots toward quantitative biomedical imaging of cells
Authors: Kang Hyeong‐Gon , Tokumasu Fuyuki , Clarke Matthew , Zhou Zhenping , Tang Jianyong , Nguyen Tinh , Hwang Jeeseong
Published: October 2009

We present results on the dynamic fluorescence properties of bioconjugated nanocrystals or quantum dots (QDs) in different chemical and physical environments. A variety of QD samples was prepared and compared: isolated individual QDs, QD aggregates, and QDs conjugated to other nanoscale materials, such as single‐wall carbon nanotubes (SWCNTs) and human erythrocyte plasma membrane proteins. We discuss plausible scenarios to explain the results obtained for the fluorescence characteristics of QDs in these samples, especially for the excitation time‐dependent fluorescence emission from clustered QDs. We also qualitatively demonstrate enhanced fluorescence emission signals from clustered QDs and deduce that the band 3 membrane proteins in erythrocytes are clustered. This approach is promising for the development of QD‐based quantitative molecular imaging techniques for biomedical studies involving biomolecule clustering. WIREs Nanomed Nanobiotechnol 2010 2 48–58

This article is categorized under:

Diagnostic Tools > In Vitro Nanoparticle-Based Sensing

Nanotechnology Approaches to Biology > Nanoscale Systems in Biology
Modeling breast biomechanics for multi‐modal image analysis—successes and challenges
Authors: Rajagopal Vijay , Nielsen Poul M. F. , Nash Martyn P.
Published: October 2009

Biomechanical modeling of the breast is a burgeoning research field that has potential uses across a wide range of healthcare applications. This review describes recent developments regarding multi‐modal breast image analysis, and outlines some of the key challenges that researchers face in introducing the models into the clinical arena. Deformable breast models have demonstrated capabilities across a wide range of breast cancer diagnoses and treatments. Specific applications include magnetic resonance (MR) image guided surgery, registration of x‐ray and MR images, and breast reduction/augmentation surgery planning. Challenges lie in improving the fidelity of these models, which are presently simplistic and use many unverified parameters. Specific challenges include characterization of individual‐specific mechanical properties of breast tissues, precise representation of loading and boundary constraints during different clinical procedures, and validation of modeling techniques used to represent key mechanical aspects such as the suspensory Cooper's ligaments. Scientists must also work towards translating their research tools into the clinical setting by developing efficient tools with user‐friendly interactivity. Widespread adoption of such techniques has the potential to significantly reduce the numbers of misdiagnosed breast cancers and enhance surgical planning for patient treatment. Copyright © 2009 John Wiley & Sons, Inc.

This article is categorized under:

Laboratory Methods and Technologies > Imaging

Models of Systems Properties and Processes > Mechanistic Models

Models of Systems Properties and Processes > Organ, Tissue, and Physiological Models
DNA methylation and gene expression
Authors: Siegfried Zahava , Simon Itamar
Published: October 2009

Methylation of cytosines is the key epigenetic modification of DNA in eukaryotes and is associated with a repressed chromatin state and inhibition of gene expression. The methylation pattern in mammalian genomes is bimodal, with most of the genomes methylated except for short DNA stretches called CpG islands (CGIs), which are generally protected from methylation. Recent technical advances have made it possible to map DNA methylation patterns on a large scale. Several genomic studies have made significant progress in unraveling the intricate relationships between DNA methylation, chromatin structure, and gene expression. What is emerging is a more dynamic and complex association between DNA methylation and expression than previously known. Here we highlight several recent genomic studies with an emphasis on what new information is gained from these studies and what conclusions can be reached about the role of DNA methylation in controlling gene expression. Copyright © 2009 John Wiley & Sons, Inc.

This article is categorized under:

Biological Mechanisms > Regulatory Biology
Monodentate Coordination of 4,4′‐Bipyridine Leading to a Supramolecular Network – Synthesis and Crystal Structure of [H2bpp][{Cu(Hbpy)2}{α‐HP2W18O62}]·4H2O
Authors: Li Jia , Wang Da‐Peng , Chen Ya‐Guang , Zhang Chun‐Jing
Published: October 2009

The new supramolecular compound [H2bpp][{Cu(Hbpy)2}{α‐HP2W18O62}]·4H2O (1) (bpy = 4,4′‐bipyridine, bpp = 1,3‐bis(4‐pyridyl)propane) was synthesized hydrothermally and characterized byelemental analysis, IR spectroscopy, thermogravimetric analysis and single‐crystal X‐ray diffraction. In compound 1, the cationic fragment [Cu(Hbpy)2]+ connects to the Dawson anion through a coordinating Cu←O bond, and the copper atom is coordinated by another polyoxoanion through a weak covalent bond with a Cu1–O26 distance of 2.879(2) Å, forming a polymeric chain. The bpy ligand in [Cu(Hbpy)2]+ adopts a monodentate coordination mode, the other nitrogen atom of the bpy ligand is protonated. The protonated Hbpy+ acts as hydrogen‐bond donor and constructs a two‐dimensional double‐sheet supramolecular network involving the one‐dimensional chains through the hydrogen bonds. The H2bpp2+ ion connects twoα‐HP2W18O626– clusters from two supramolecular networks through hydrogen bonds and creates a three‐dimensional supramolecular architecture. The thermal decomposition of 1 happens over a wide temperature range (450–800 °C), which indicates that it might include complicated oxidation–reduction processes.
Intramolekulare Ringerweiterung eines 2‐Lithium‐anilido‐2‐fluoro‐1,3‐diaza‐2‐silacyclopentens zum 1,3,5‐Triaza‐7‐bora‐2‐silacyclohepten – Experimentelle und Quantenchemische Ergebnisse
Authors: Abraham Sascha , Schmatz Stefan , Klingebiel Uwe , Fischer Andreas
Published: October 2009

The reaction between the lithiated 2‐diisopropylanilino‐2‐fluoro‐1,3‐diaza‐2‐silacyclopentene, (HCNCMe3)2SiFNLi(2,6‐Me2CH)2C6H3 (I), and BF3·OEt2 in THF afforded in an unknown, intramolecular ring expansion the seven‐membered 1,3,4‐triaza‐7‐bora‐2‐silacycloheptene, (HCNCMe3)2(SiF2)BFN‐2,6‐(Me2CH)2C6H3 (1). Starting with the BF2‐substituted compound A, quantum‐chemical calculations on the thermal isomeration process revealed a two‐step reaction mechanism: First, the bicyclic compound C is formed via transition state TS1, and second, a 1,3‐fluoride ion migration occurs in the seven‐membered transition state TS2 from a BF2‐ to a SiF‐unit. The reaction mechanism and the structures of the transition states are discussed in detail.
There are big gaps in our knowledge, and thus approach, to zoo animal welfare: a case for evidence‐based zoo animal management
Authors: Melfi V. A.
Published: October 2009

There are gaps in knowledge that hinder our ability within zoos to provide good animal welfare. This does not mean that zoos cannot or do not provide good welfare, only that currently this goal is hindered. Three reasons for these gaps are identified as: (1) there is an emphasis on the identification and monitoring of indicators that represent poor welfare and it is assumed that an absence of poor welfare equates to good welfare. This assumption is overly simplistic and potentially erroneous; (2) our understanding of how housing and husbandry (H&H) affects animals is limited to a small set of variables determined mostly by our anthropogenic sensitivities. Thus, we place more value on captive environmental variables like space and companionship, ignoring other factors that may have a greater impact on welfare, like climate; (3) finally, whether intentional or not, our knowledge and efforts to improve zoo animal welfare are biased to very few taxa. Most attention has been focused on mammals, notably primates, large cats, bears, and elephants, to the exclusion of the other numerous species about which very little is known. Unfortunately, the extent to which these gaps limit our ability to provide zoo animals with good welfare is exacerbated by our over reliance on using myth and tradition to determine zoo animal management. I suggest that we can fill these gaps in our knowledge and improve our ability to provide zoo animals with good welfare through the adoption of an evidence‐based zoo animal management framework. This approach uses evidence gathered from different sources as a basis for making any management decisions, as good quality evidence increases the likelihood that these decisions result in good zoo animal welfare. Zoo Biol 28:574–588, 2009. © 2009 Wiley‐Liss, Inc.
Isorhizochalin: a Minor Unprecedented Bipolar Sphingolipid of Stereodivergent Biogenesis from the Rhizochalina incrustata
Authors: Makarieva Tatyana N. , Zakharenko Alexander M. , Dmitrenok Pavel S. , Guzii Alla G. , Denisenko Vladimir A. , Savina Alexandra S. , Dalisay Doralyn S. , Molinski Tadeusz F. , Stonik Valentin A.
Published: October 2009

Isorhizochalin (1) was isolated as its peracetate from the EtOH extract of the sponge Rhizochalina incrustata. Its structure and absolute stereochemistry were elucidated as (2S,3R,26R,27R)‐2,27‐diamino‐3‐O‐β‐d‐galactopyranosyl‐oxy‐26‐hydroxyoctacosan‐18‐one by extensive NMR, MS studies, chemical transformations, including micromolar‐scale Baeyer–Villiger oxidation, and by analysis of CD spectra of isorhizochalinin perbenzoate (2b). Isorhizochalin is an unprecedented C‐2 epimer of rhizochalin having an erythro configuration at the glycosylated 2‐amino‐3‐alkanol α‐terminus in contrast with a canonical threo configuration for other representatives of this structural group. Probable biogenesis of 1 is discussed in the context of known sphingolipid biosynthesis beginning with condensation of alanine with a fatty acyl CoA thioester. The aglycone, isorhizochalinin (2a), shows cytotoxicity against human leukemia HL‐60 and THP‐1 cells with IC50 values of 2.90 and 2.20 μM, respectively.
Do illness perceptions predict pain‐related disability and mood in chronic orofacial pain patients? A 6‐month follow‐up study
Authors: Galli Ursula , Ettlin Dominik A. , Palla Sandro , Ehlert Ulrike , Gaab Jens
Published: October 2009

In our study, we investigated the predictive value of illness beliefs as measured by the revised illness perception questionnaire (IPQ‐R) in the context of other clinical predictors in patients with chronic orofacial pain over a 6‐month follow‐up period. Consecutive patients (152) referred to the interdisciplinary orofacial pain service at the Centre for Dental and Oral Medicine and Cranio‐Maxillofacial Surgery, University of Zurich received questionnaires to assess pain and pain‐related disability, anxiety, depression as well as physical and mental quality of life at three time points: prior to treatment, 3 and 6 months after beginning of treatment. Results: significant improvement was found over time for all outcome measures except mental quality of life. Results of the regression analysis indicated that believing pain could have serious consequences on one's life (IPQ subscale consequences) is one of the most important predictors for treatment outcome. The belief in low personal control and in a chronic timeline is also shown to be predictive for outcome, though explaining a smaller proportion of variance. These results provided evidence that beliefs about pain are important predictors for treatment outcome even when controlled for pain and mood. They therefore need to be considered in the management of patients with chronic orofacial pain. Assessing patients’ illness beliefs can provide essential information on these important psychological determinants of adjustment to chronic pain and may be specific targets for individualised treatment approaches.
Simple, realistic models of complex biological processes: Positive feedback and bistability in a cell fate switch and a cell cycle oscillator
Authors: Ferrell James E. , Pomerening Joseph R. , Kim Sun Young , Trunnell Nikki B. , Xiong Wen , Huang Chi-Ying Frederick , Machleder Eric M.
Published: October 2009

Here we review some of our work over the last decade on Xenopus oocyte maturation, a cell fate switch, and the Xenopus embryonic cell cycle, a highly dynamical process. Our approach has been to start with wiring diagrams for the regulatory networks that underpin the processes; carry out quantitative experiments to describe the response functions for individual legs of the networks; and then construct simple analytical models based on chemical kinetic theory and the graphical rate‐balance formalism. These studies support the view that the all‐or‐none, irreversible nature of oocyte maturation arises from a saddle–node bifurcation in the regulatory system that drives the process, and that the clock‐like oscillations of the embryo are built upon a hysteretic switch with two saddle–node bifurcations. We believe that this type of reductionistic systems biology holds great promise for understanding complicated biochemical processes in simpler terms.
Adding structural information to the von Hippel–Lindau (VHL) tumor suppressor interaction network
Authors: Leonardi E. , Murgia A. , Tosatto S.C.E.
Published: October 2009

The von Hippel–Lindau (VHL) tumor suppressor gene is a protein interaction hub, controlling numerous genes implicated in tumor progression. Here we focus on structural aspects of protein interactions for a list of 35 experimentally verified protein VHL (pVHL) interactors. Using structural information and computational analysis we have located three distinct interaction interfaces (A, B, and C). Interface B is the most versatile, recognizing a refined linear motif present in 17 otherwise non‐related proteins. It has been possible to distinguish compatible and exclusive interactions by relating pVHL function to interaction interfaces and subcellular localization. A novel hypothesis is presented regarding the possible function of the N‐terminus as an inhibitor of pVHL function.
Coordination of gene expression with growth rate: A feedback or a feed‐forward strategy?
Authors: Levy Sagi , Barkai Naama
Published: October 2009

In the budding yeast, a large fraction of genes is coordinately regulated with growth rate. We argue that this correlation does not reflect a direct feedback from growth rate to gene expression. Rather, what appears to be a response to growth rate is dominated by environmental sensing. External parameters, such as nutrition or temperature, feed‐forward to define gene expression pattern that is tuned to the evolutionary‐predicted growth rate. While such a feed‐forward strategy requires fine‐tuning of signaling mechanisms, and is limited in the range of environments that can be monitored, it enables advanced preparation to physiological changes that predictably occur following environmental switching. The capacity to anticipate and prepare for changing conditions was probably a major selection force during yeast evolution.
Evaluating Postoperative Pain in Monopolar Cautery Versus Harmonic Scalpel Tonsillectomy
Authors: Cushing Sharon L. , Smith Oakley , Chiodo Albino , Elmasri William , Munro‐Peck Pam
Published: October 2009

OBJECTIVES

To compare postoperative pain between monopolar cautery tonsillectomy and harmonic scalpel tonsillectomy (HST).

STUDY DESIGN

Randomized controlled trial using paired organs.

SETTING

Community hospital with academic affiliation.

SUBJECTS

One hundred and fourteen consecutive patients six years of age or older undergoing tonsillectomy for indications of hypertrophy or recurrent infection.

METHODS

For each subject, monopolar cautery tonsillectomy was performed by four senior surgeons on one side and HST was performed on the other side. Allocation of technique to side was randomized and revealed to the surgeon at the start of the operation. Validated visual analog pain scales were used to quantify pain at rest and with swallowing for each side and were completed daily for 14 days. All subjects were prescribed weight‐equivalent doses of analgesics. Secondary outcome measures included postoperative complications (hemorrhage and readmission).

RESULTS

Pairwise comparisons of pain scores revealed no significant difference between monopolar cautery tonsillectomy and HST (P < 0.05).

CONCLUSIONS

Subjects undergoing monopolar cautery tonsillectomy do not experience increased postoperative pain in comparison to HST.
Comparison of the effects of a liquid yogurt and chocolate bars on satiety: a multidimensional approach
Authors: Chapelot Didier , Payen Flore
Published: October 2009

In the context of epidemic obesity, satiety is an important target for nutritional interventions. Using a multidimensional approach, we compared the effect on satiety of two food products frequently consumed in France by young adults as a small mid-afternoon meal called the ‘goûter’. Participants were eighteen healthy young males (aged 20·8 (sd1·8) years) of normal body weight (BMI 21·7 (sd1·7) kg/m2) used to eating four times per d including a ‘goûter’. On two occasions, under laboratory conditions, the time-blinded participants consumed a fixed energy lunch (2·8 MJ) and, 240 min later, either a liquid yogurt or chocolate bars matched for energy (1·2 MJ) and weight (366 g). Then, satiety was assessed by: (1) ratings of hunger, appetite, desire to eat and fullness at 20 min intervals (perception), (2) the delay until the subject requested his dinner meal (duration) and (3) energy intake at this meal (consumption). Results showed that satiety was perceived higher after liquid yogurt than chocolate bars over the 60 min preceding the next meal, as evidenced by hunger (P < 0·005), appetite, (P < 0·005), desire to eat (P < 0·04) and fullness (P < 0·05) ratings. However, its duration was similar between liquid yogurt and chocolate bars (165 (se8) and 174 (se7) min respectively) and this difference was not followed by reduced intake at dinner. In conclusion, this approach of satiety revealed that a liquid yogurt induced a lower subjective motivation to eat than chocolate bars during the hour preceding the spontaneous onset of a meal, without affecting subsequent food intake.
Acceleration, pressure and related quantities in the proximity of the turbulent/non-turbulent interface
Authors: HOLZNER MARKUS , LÜTHI B. , TSINOBER A. , KINZELBACH W.
Published: October 2009

This paper presents an analysis of flow properties in the proximity of the turbulent/non-turbulent interface (TNTI), with particular focus on the acceleration of fluid particles, pressure and related small scale quantities such as enstrophy,ω2=ωiωi, and strain,s2=sijsij. The emphasis is on the qualitative differences between turbulent, intermediate and non-turbulent flow regions, emanating from the solenoidal nature of the turbulent region, the irrotational character of the non-turbulent region and the mixed nature of the intermediate region in between. The results are obtained from a particle tracking experiment and direct numerical simulations (DNS) of a temporally developing flow without mean shear. The analysis reveals that turbulence influences its neighbouring ambient flow in three different ways depending on the distance to the TNTI: (i) pressure has the longest range of influence into the ambient region and in the far region non-local effects dominate. This is felt on the level of velocity as irrotational fluctuations, on the level of acceleration as local change of velocity due to pressure gradients, Du/Dt≃ ∂u/∂t≃ −∇p/ρ, and, finally, on the level of strain due to pressure-Hessian/strain interaction, (D/Dt)(s2/2) ≃ (∂/∂t)(s2/2) ≃ −sijp,ij> 0; (ii) at intermediate distances convective terms (both for acceleration and strain) as well as strain production −sijsjkski> 0 start to set in. Comparison of the results at Taylor-based Reynolds numbersReλ= 50 andReλ= 110 suggests that the distances to the far or intermediate regions scale with the Taylor microscale λ or the Kolmogorov length scale η of the flow, rather than with an integral length scale; (iii) in the close proximity of the TNTI the velocity field loses its purely irrotational character as viscous effects lead to a sharp increase of enstrophy and enstrophy-related terms. Convective terms show a positive peak reflecting previous findings that in the laboratory frame of reference the interface moves locally with a velocity comparable to the fluid velocity fluctuations.
Meta-analysis of CSF and MRI biomarkers for detecting preclinical Alzheimer's disease
Authors: Schmand B. , Huizenga H. M. , van Gool W. A.
Published: October 2009

Background

Abnormal levels of biomarkers in cerebrospinal fluid (CSF) and atrophy of medial temporal lobe (MTL) structures on magnetic resonance imaging (MRI) are being used increasingly to diagnose early Alzheimer's disease (AD). We evaluated the claim that these biomarkers can detect preclinical AD before behavioural (i.e. memory) symptoms arise.

Method

We included all relevant longitudinal studies of CSF and MRI biomarkers published between January 2003 and November 2008. Subjects were not demented at baseline but some declined to mild cognitive impairment (MCI) or to AD during follow-up. Measures of tau and beta-amyloid in CSF, MTL atrophy on MRI, and performance on delayed memory tasks were extracted from the papers or obtained from the investigators.

Results

Twenty-one MRI studies and 14 CSF studies were retrieved. The effect sizes of total tau (t-tau), phosphorylated tau (p-tau) and amyloid beta 42 (aβ42) ranged from 0.91 to 1.11. The effect size of MTL atrophy was 0.75. Memory performance had an effect size of 1.06. MTL atrophy and memory impairment tended to increase when assessed closer to the moment of diagnosis, whereas effect sizes of CSF biomarkers tended to increase when assessed longer before the diagnosis.

Conclusions

Memory impairment is a more accurate predictor of early AD than atrophy of MTL on MRI, whereas CSF abnormalities and memory impairment are about equally predictive. Consequently, the CSF and MRI biomarkers are not very sensitive to preclinical AD. CSF markers remain promising, but studies with long follow-up periods in elderly subjects who are normal at baseline are needed to evaluate this promise.
Trajectories of change in depression severity during treatment with antidepressants
Authors: Uher R. , Muthén B. , Souery D. , Mors O. , Jaracz J. , Placentino A. , Petrovic A. , Zobel A. , Henigsberg N. , Rietschel M. , Aitchison K. J. , Farmer A. , McGuffin P.
Published: October 2009

Background

Response and remission defined by cut-off values on the last observed depression severity score are commonly used as outcome criteria in clinical trials, but ignore the time course of symptomatic change and may lead to inefficient analyses. We explore alternative categorization of outcome by naturally occurring trajectories of symptom change.

Method

Growth mixture models were applied to repeated measurements of depression severity in 807 participants with major depression treated for 12 weeks with escitalopram or nortriptyline in the part-randomized Genome-based Therapeutic Drugs for Depression study. Latent trajectory classes were validated as outcomes in drug efficacy comparison and pharmacogenetic analyses.

Results

The final two-piece growth mixture model categorized participants into a majority (75%) following a gradual improvement trajectory and the remainder following a trajectory with rapid initial improvement. The rapid improvement trajectory was over-represented among nortriptyline-treated participants and showed an antidepressant-specific pattern of pharmacogenetic associations. In contrast, conventional response and remission favoured escitalopram and produced chance results in pharmacogenetic analyses. Controlling for drop-out reduced drug differences on response and remission but did not affect latent trajectory results.

Conclusions

Latent trajectory mixture models capture heterogeneity in the development of clinical response after the initiation of antidepressants and provide an outcome that is distinct from traditional endpoint measures. It differentiates between antidepressants with different modes of action and is robust against bias due to differential discontinuation.
Plantinga's version of the free-will argument: the good and evil that free beings do
Authors: HIMMA KENNETH EINAR
Published: October 2009

According to Plantinga's version of the free-will argument (FWA), the existence of free beings in the world who, on the whole, do more good than evil is the greater moral good that cannot be secured by even an omnipotent God without allowing some evil and thereby shows the logical compatibility of God with evil. In this essay, I argue that there are good empirical and moral reasons, from the standpoint of one plausible conception of Christian ethics, to doubt that Plantinga's version of the FWA succeeds as a theodicy. In particular, I argue that, given this understanding of Christian ethics, it seems reasonable to think it false that free beings are doing more good than evil in the world. While there are surely possible worlds in which free beings do more good than evil, this material world seems clearly not one of those. Thus, while Plantinga's version might succeed as a defence against the logical problem of evil, it will neither rebut the evidential problem of evil nor, without more, ground a successful theodicy that reconciles God's existence with the evil that occurs in this world.
On the compact real form of the Lie algebra 2
Authors: WILSON ROBERT A.
Published: October 2009

We give an elementary construction of the compact real form of the Lie algebra 2. This construction exhibits the group 23·L3(2) as a group of automorphisms. We also show that there is a unique 14-dimensional real Lie algebra invariant under the action of this group.
Trypanocidal drugs: mechanisms, resistance and new targets
Authors: Wilkinson Shane R. , Kelly John M.
Published: October 2009

The protozoan parasitesTrypanosoma bruceiandTrypanosoma cruziare the causative agents of African trypanosomiasis and Chagas disease, respectively. These are debilitating infections that exert a considerable health burden on some of the poorest people on the planet. Treatment of trypanosome infections is dependent on a small number of drugs that have limited efficacy and can cause severe side effects. Here, we review the properties of these drugs and describe new findings on their modes of action and the mechanisms by which resistance can arise. We further outline how a greater understanding of parasite biology is being exploited in the search for novel chemotherapeutic agents. This effort is being facilitated by new research networks that involve academic and biotechnology/pharmaceutical organisations, supported by public–private partnerships, and are bringing a new dynamism and purpose to the search for trypanocidal agents.
The haptic abilities of the human newborn
Authors: Streri Arlette , Gentaz Edouard
Published: October 2009

Abstract. How do human babies gain knowledge by touch? This review presents information on the haptic abilities of human newborns and preterm infants which sheds light on this question. How do full-term and preterm newborns perceive information and form a perceptual representation of objects extracted from the hands alone? How do full-term newborns transfer this information to vision in an intermodal process? Using a habituation/dishabituation procedure, experiments have revealed that preterm and full-term newborns are able to discriminate object shapes in the manual, as well as in the visual modalities for full-term newborns. These abilities are a prerequisite for the establishment of relations between haptic and visual sensory information in cross-modal transfer tasks. We discuss several experiments performed using an intersensory successive preference procedure which provide evidence for cross-modal recognition from touch to vision from birth in full-term newborns. The links, however, are limited, partial, and not always reciprocal. We discuss these results in the light of recent theories on visual-haptic links.
Neue methodische Ansätze zur Erfassung der Beziehung zwischen Wahrnehmung und Handlung in früher Kindheit
Authors: Hauf Petra
Published: October 2009

Zusammenfassung. Die vorliegende Untersuchung zum Zusammenhang von Wahrnehmung und Handlung in früher Kindheit konnte unter Verwendung innovativer Eyetracking Technologie belegen, dass die aktive Handlungsausführung einen direkten Einfluss auf die nachfolgende Wahrnehmung von Handlungen anderer hat. Neun- und Elfmonatige betrachteten länger den Handlungsbereich in einem Video, wenn die Handlung mit einem Objekt ausgeführt wurde, mit dem sie bereits eigene Erfahrung gesammelt hatten (Experiment 1). Umgekehrt zeigte sich ein Einfluss von wahrgenommenen Handlungen auf die Ausführung eigener Handlungen. Beide Altersgruppen fokussierten bei der Betrachtung eines Videos länger auf das Handlungsobjekt als auf ein statisches Objekt und wählten in der nachfolgenden Handlungsphase das gleiche Objekt aus und spielten länger damit (Experiment 2). Die Befunde untermauern einen angenommenen direkten Zusammenhang von Wahrnehmung und Handlung bereits im ersten Lebensjahr.
Frühkindliche Handlungswahrnehmung und Theory of Mind
Authors: Henning Anne , Daum Moritz M. , Aschersleben Gisa
Published: October 2009

Zusammenfassung. Die entwicklungspsychologische Forschung beschäftigt sich zunehmend mit der Bedeutung von frühkindlicher Handlungswahrnehmung und -kontrolle für die spätere Entwicklung sozial-kognitiver Fähigkeiten. Dabei ist insbesondere die Frage von Interesse, inwieweit das frühkindliche Verständnis auf Zielobjekte gerichteter Handlungen eine mögliche Vorläuferkompetenz einer Theory of Mind sein könnte. In dem vorliegenden Artikel differenzieren wir zwischen nicht-mentalistischem (auf struktureller Handlungsanalyse basierendem) und mentalistischem (auf mentale Konzepte zurückgreifendem) Handlungsverständnis und stellen die Hypothese auf, dass das nicht-mentalistische Verständnis menschlicher Handlungen im Säuglingsalter eine wichtige Vorläuferkompetenz der mentalistischen Interpretation dieser Handlungen durch die Zuschreibung mentaler Zustände wie Intentionen darstellt. Wir untermauern diese Hypothese mit einem Überblick über die jüngsten Befunde aus längsschnittlichen Untersuchungen, die mit der Annahme einer Kontinuität in der sozial-kognitiven Entwicklung im Bereich des Handlungsverständnisses konsistent sind.
Atmospheric soluble dust records from a Tibetan ice core: Possible climate proxies and teleconnection with the Pacific Decadal Oscillation
Authors: Grigholm B. , Mayewski P. A. , Kang S. , Zhang Y. , Kaspari S. , Sneed S. B. , Zhang Q.
Published: October 2009

In autumn 2005, a joint expedition between the University of Maine and the Institute of Tibetan Plateau Research recovered three ice cores from Guoqu Glacier (33°34′37.8″N, 91°10′35.3″E, 5720 m above sea level) on the northern side of Mt. Geladaindong, central Tibetan Plateau. Isotopes (δ18O), major soluble ions (Na+, K+, Mg2+, Ca2+, Cl−, NO3−, SO42−), and radionuclide (β‐activity) measurements from one of the cores revealed a 70‐year record (1935–2005). Statistical analysis of major ion time series suggests that atmospheric soluble dust species dominate the chemical signature and that background dust levels conceal marine ion species deposition. The soluble dust time series have interspecies relations and common structure (empirical orthogonal function (EOF) 1), suggesting a similar soluble dust source or transport route. Annual and seasonal correlations between the EOF 1 time series and National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis climate variables (1948–2004) suggest that the Mt. Geladaindong ice core record provides a proxy for local and regional surface pressure. An approximately threefold decrease of soluble dust concentrations in the middle to late 1970s, accompanied by regional increases in pressure and temperature and decreases in wind velocity, coincides with the major 1976–1977 shift of the Pacific Decadal Oscillation (PDO) from a negative to a positive state. This is the first ice core evidence of a potential teleconnection between central Asian atmospheric soluble dust loading and the PDO. Analysis of temporally longer ice cores from Mt. Geladaindong may enhance understanding of the relationship between the PDO and central Asian atmospheric circulation and subsequent atmospheric soluble dust loading.
Particulate matter air quality assessment using integrated surface, satellite, and meteorological products: 2. A neural network approach
Authors: Gupta Pawan , Christopher Sundar A.
Published: October 2009

In recent years, sparse, surface‐based air quality monitoring has been improved by using wide‐swath, satellite‐derived aerosol products. However, satellites are sensitive to the entire aerosol column, not only the aerosol near the surface that impacts human health. In part 1 of this series, we used multiple regression to demonstrate how inclusion of meteorological analyses can help constrain the surface level proportion of the aerosol profile and improve the estimate of surface PM2.5. Here, instead of multiple regression technique, we describe an artificial neural network (ANN) framework that reduces the uncertainty of surface PM estimation from satellite data. We use 3 years of MODIS aerosol optical thickness data at 0.55μm and meteorological analyses from the rapid update cycle to estimate surface level PM2.5 over the southeast United States (EPA region 4). As compared to regression coefficients obtained through simple correlation (R = 0.60) or multiple regression (R = 0.68) techniques, the ANN derives hourly PM2.5 data that compare with observations with R = 0.74. For estimating daily mean PM2.5, the ANN techniques results in correlation of R = 0.78. Although the degree of improvement varies over different sites and seasons, this study demonstrates the potential for using ANN for operational air quality monitoring.
Hydrogeomorphic edge detection and delineation of landscape functional units from lidar digital elevation models
Authors: Richardson Murray C. , Fortin M.‐J. , Branfireun B. A.
Published: October 2009

A new method is introduced to delineate hydrogeomorphic elements from light detection and ranging (lidar) digital elevation models. Landscape segmentation is achieved using an edge‐detection procedure to identify boundaries defining rapid changes in the tan αd index of landscape drainage potential. These boundaries define homogenous, functional landscape units that can be classified according to different topographically derived indices such as mean of the expected hydraulic gradient (approximated by tan αd), mean topographic wetness index, and mean ratio of flow path lengths to flow path gradients (L/G). Two case studies are presented in which the new method was applied (1) to map forested wetlands and nonwetland saturation‐prone depressional areas and improve regression models of dissolved organic carbon source areas in the Muskoka‐Haliburton region of south central Ontario and (2) to spatially characterize near‐surface soil moisture patterns along a complex, upland hillslope catena in a small experimental watershed in northwestern Ontario. Both case studies point to the critical role of local drainage conditions and slope geometry in dictating spatial patterns of terrain wetness in complex Boreal Shield landscapes. The results cast uncertainty on the role of upslope contributing area as a first‐order control on terrain wetness in this environment. Nevertheless, the results highlight the strong potential of digital terrain analysis to improve conceptualization of hydrological processes in the Boreal Shield, and they are conceptually consistent with the emerging paradigm of runoff generation in this region. We propose hydrogeomorphic edge detection and classification as a way to improve the characterization of landscape functional units in Boreal Shield watersheds for process‐oriented and model‐based ecohydrological research.
Magnetopause reconnection impact parameters from multiple spacecraft magnetic field measurements
Authors: Wendel Deirdre E. , Reiff Patricia H.
Published: October 2009

We present a novel technique that exploits multiple spacecraft data to determine the impact parameters of the most general form of magnetic reconnection at the magnetopause. The method consists of a superposed epoch of multiple spacecraft magnetometer measurements that yields the instantaneous magnetic spatial gradients near a magnetopause reconnection site. The gradients establish the instantaneous positions of the spacecraft relative to the reconnection site. The analysis is well suited to evaluating the spatial scales of singular field line reconnection, which is characterized by a two‐dimensional x‐type topology adjacent and perpendicular to a reconnecting singular field line. Application of the method to Cluster data known to lie in the vicinity of a northward IMF reconnection site establishes a field topology consistent with singular field line reconnection and a normal magnetic field component of 20 nT. The corresponding current structure consists of a 130 km sheet possibly embedding a thinner, bifurcated sheet.
A deep mantle source for high 3He/4He ocean island basalts (OIB) inferred from Pacific near‐ridge seamount lavas
Authors: Hahm D. , Castillo P. R. , Hilton D. R.
Published: October 2009

One of the most contentious issues in the debate on the origin of volcanic island and seamount chains is the significance of high 3He/4He ratios at such locations. The contemporary hotspot hypothesis calls for the high 3He/4He signature to be derived from a distinct source reservoir that lies deep in the mantle. The competing plate stress hypothesis claims that extreme isotopic signals, such as the high 3He/4He, come from dispersed crustal lithologies in the upper mantle. Here, we show that lavas from the East Pacific Rise–the ridge axis and near‐ridge seamounts, which have radiogenic isotope compositions overlapping with other Pacific OIB, do not have high 3He/4He ratios. This suggests that high 3He/4He is not associated with dispersed, heterogeneous lithologies embedded in the upper mantle. We conclude that the mantle source of high 3He/4He OIB is unique to volcanic island and seamount chains and likely resides at depth in the mantle.
Aura Microwave Limb Sounder observations of the Northern Annular Mode: From the mesosphere to the upper troposphere
Authors: Lee Jae N. , Wu Dong L. , Manney Gloria L. , Schwartz Michael J.
Published: October 2009

Vertical structure and evolution of the wintertime Northern Hemisphere Annular Mode (NAM), the first Empirical Orthogonal Function (EOF) of geopotential height anomalies, are constructed from the 2005–2009 Aura Microwave Limb Sounder (MLS) measurements in the entire middle atmosphere between 316 hPa (∼9 km) and 0.001 hPa (∼90 km). This is the first report of NAM structure extending into the mesosphere. The mode appears to be robust and it accounts for up to 70% of middle‐atmospheric variance before decreasing in the upper mesosphere. The vertical connection of the NAM modes suggests strong dynamic coupling between the mesosphere and stratosphere. Time evolution of the NAM suggests that the significant NAM anomalies typically appear first in the mesosphere and progress downward. NAM patterns derived from MLS observations are consistent with those derived from long‐term reanalysis below the middle stratosphere. The NAM indexes show the mesospheric cooling signals during the major stratospheric sudden warmings (SSWs) in 2006 and 2009.
Influence of changes in sea ice concentration and cloud cover on recent Arctic surface temperature trends
Authors: Liu Yinghui , Key Jeffrey R. , Wang Xuanji
Published: October 2009

The influence of trends in sea ice concentration (SIC) and cloud cover on trends in surface temperature over the Arctic Ocean from 1982 to 2004 is investigated analytically, and evaluated empirically with satellite products. The results demonstrate that changes in SIC and cloud cover played major roles in the magnitude of recent Arctic surface temperature trends. Significant surface warming associated with sea ice loss, over 0.9 K decade−1, is found over the Chukchi and Beaufort Seas in autumn, accounting for most of the observed 1.1 K decade−1 warming trend. If the mean SIC over the Arctic Ocean in each season is reduced by half, our analysis shows that the surface temperature will increase by approximately 10 K in winter and 6 K in spring and autumn. In winter, surface temperature trends associated with changes in cloud cover are negative over most of the Arctic Ocean, and with cloud cover trends explaining −0.91 out of −1.2 K decade−1 of the surface temperature cooling. In spring, 0.55 K decade−1 of the total 1.0 K decade−1 warming can be attributed to the trend associated with cloud cover changes. After eliminating the effects of changes in SIC and cloud cover on surface temperature trends, the residual surface temperature trends can be used in a more robust diagnosis of surface warming or cooling in the Arctic. The same procedure can be applied to study the impact of changes in sea ice thickness, ocean inflow, and other parameters on the temperature trends, and to completely different sets of climate variables, whether they are measured or modeled.
Aerosol optical depth in clean marine and continental northeast Atlantic air
Authors: Mulcahy J. P. , O'Dowd C. D. , Jennings S. G.
Published: October 2009

The aerosol optical depth (AOD) and Ångström exponent for the period 2002–2004 is evaluated for clean marine and continentally influenced air masses over the northeast Atlantic region. Measurements were carried out at the Mace Head atmospheric research station on the west coast of Ireland using a precision filter radiometer which measures the aerosol optical depth at four wavelengths centered at 368, 412, 500, and 862 nm. The clean marine AOD at 500 nm is characterized by a mean value of 0.14 ± 0.06, exhibiting relatively small temporal variability. The Ångström exponent was less than 1 for the majority of cases, having an average value of 0.40 ± 0.29 in clean marine conditions. The latter is consistent with the presence of relatively large supermicron particles, such as sea salt dominating the marine aerosol size distribution. The Ångström exponent shows a distinct seasonal cycle in clean marine air, with maximum values being derived in the summer months and minimum values in the winter. In continental air masses, while the range and standard deviation of the AOD is larger than in clean marine conditions, the overall mean AOD (τ500 = 0.19 ± 0.12) is comparable with the clean marine AOD. The continental Ångström exponent is larger, having a mean value of 1.07 ± 0.32. This is attributed to a dominating accumulation mode in the presence of urban‐industrial aerosol particles originating mainly from continental Europe. These results demonstrate how the natural marine AOD can rival polluted AOD over the northeast Atlantic region and highlight the importance of the natural marine aerosol contribution over oceans.
Observational signature of the direct radiative effect by natural boreal forest aerosols and its relation to the corresponding first indirect effect
Authors: Lihavainen Heikki , Kerminen Veli‐Matti , Tunved Peter , Aaltonen Veijo , Arola Antti , Hatakka Juha , Hyvärinen Antti , Viisanen Yrjö
Published: October 2009

By using a screened set of long‐term aerosol measurement data, the contribution of natural boreal forest aerosols to the direct radiative effect (DRE) was observed at a remote continental site in northern Finland. Averaged over the summer season, the magnitude of this effect at the top of the atmosphere was estimated to be in the range −(0.37–0.74) W m−2 in our study region and possibly somewhat higher over the whole boreal forest region. Globally, the DRE owing to boreal forest aerosols is much smaller than that owing to natural sea salt or dust aerosols, as well as direct radiative forcing by anthropogenic aerosols. We also updated the earlier estimates of the first indirect radiative effect (IRE) by natural boreal forest aerosols. We found that this IRE is likely to be substantially higher, perhaps more than an order of magnitude, than the corresponding DRE.
Aerosol‐CO relationship and aerosol effect on ice cloud particle size: Analyses from Aura Microwave Limb Sounder and Aqua Moderate Resolution Imaging Spectroradiometer observations
Authors: Jiang Jonathan H. , Su Hui , Massie Steven T. , Colarco Peter R. , Schoeberl Mark R. , Platnick Steven
Published: October 2009

We examine the relation between Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol optical thickness (AOT) and Aura Microwave Limb Sounder upper tropospheric (UT) carbon monoxide (CO) to address when CO can be used as a proxy for aerosols. Ice cloud effective radii (re), also from Aqua MODIS, are also analyzed to investigate possible aerosol effects on ice clouds. Our analysis focuses on five regions where ice clouds are collocated with high UT CO loadings: South America (SAM), southern Africa (SAF), northern Africa (NAF), South Asia (SAS), and East Asia (EAS). We find three levels of AOT to CO sensitivity. High AOT sensitivity to CO is characterized by a rapid increase of AOT when CO increases. SAM in August–November and SAF in June–September fall into this category. Moderate AOT sensitivity to CO is characterized by moderate increase of AOT with CO. It includes SAF in October–May, NAF in January–March, SAS in all months, and EAS in August–September. The other months for each region fall into the low sensitivity category. The variations of sensitivity in different regions and seasons result from different emission sources coupled with dynamic influence. CO can be used as an aerosol proxy for the “high” and “moderate” sensitivity cases. During those times,refor polluted clouds is smaller than that for clean clouds, suggesting an indirect effect of aerosol on ice clouds. CO is not a good aerosol index in the low sensitivity cases, in which polluted clouds defined by CO loadings do not show significant differences from clean clouds inre.