bluuebunny/crossref_metadata_2025 huggingface dataset:
Few‐parameter exponentially correlated wavefunctions for the ground state of lithium
Authors: Albert Victor V. , Guevara Nicolais L. , Sabin John R. , Harris Frank E.
Published: August 2009

Compact, but relatively accurate wavefunctions for the ground state of the Li atom were obtained through the use of a limited basis of exponentially correlated functions with optimized nonlinear parameters. In contrast to our earlier work, the basis contains pre‐exponential factors that improve the rate of convergence of the basis‐set expansion. The matrix elements needed in the present work were evaluated analytically using recursive methods reported recently by one of us; a check on the programming was provided by comparison with numerical evaluations carried out by Turbiner and Guevara. The rate of convergence of the expansion is compared with those of Hylleraas‐basis computations, and a comparison is also made with exponentially correlated studies of He‐like systems. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Distinguishing a phosphate ester prodrug from its isobaric sulfate metabolite by mass spectrometry without the metabolite standard
Authors: Wu Steven T. , Cao Kai , Bonacorsi Samuel J. , Zhang Hongwei , Jemal Mohammed
Published: August 2009

A phosphate prodrug of a phenolic or alcoholic drug is isobaric with the putative sulfate metabolite of the drug. During liquid chromatography/tandem mass spectrometry (LC/MS/MS) analysis of biological samples obtained after the administration of a phosphate prodrug, a product ion arising from the parent drug portion of the prodrug molecule is commonly used in selected reaction monitoring (SRM) utilized for the simultaneous quantitation of the prodrug and the in vivo generated parent drug. While the advantage of using a drug moiety‐specific LC‐SRM method is obvious, one drawback is that the sulfate metabolite will also respond to such an SRM transition since the metabolite will invariably yield the same product ion as the prodrug. Thus, the sulfate metabolite could be mistaken for the prodrug unless chromatographic separation between the two is achieved. In the absence of a reference standard for the sulfate metabolite to demonstrate chromatographic separation, it is important to establish a procedure that can ascertain the absence of the sulfate metabolite in the study samples to ensure the specificity of the method for the prodrug. To this end, we studied the MS/MS behavior of model phosphate and sulfate ester compounds and developed a procedure based on phosphate‐specific and sulfate‐specific product ions for distinguishing the phosphate prodrug from the sulfate metabolite. Copyright © 2009 John Wiley & Sons, Ltd.
Online high‐precision δ2H and δ18O analysis in water by pyrolysis
Authors: Lu Feng H.
Published: August 2009

A method for online simultaneous δ2H and δ18O analysis in water by high‐temperature conversion is presented. Water is injected by using a syringe into a high‐temperature carbon reactor and converted into H2 and CO, which are separated by gas chromatography (GC) and carried by helium to the isotope ratio mass spectrometer for hydrogen and oxygen isotope analysis. A series of experiments was conducted to evaluate several issues such as sample size, temperature and memory effects. The δ2H and δ18O values in multiple water standards changed consistently as the reactor temperature increased from 1150 to 1480°C. The δ18O in water can be measured at a lower temperature (e.g. 1150°C) although the precision was relatively poor at temperatures <1300°C. Memory effects exist for δ2H and δ18O between two waters, and can be reduced (to <1%) with proper measures. The injection of different amounts of water may affect the isotope ratio results. For example, in contrast to small injections (100 nL or less) from small syringes (e.g. 1.2 µL), large injections (1 µL or more) from larger syringes (e.g. 10 µL) with dilution produced asymmetric peaks and shifts of isotope ratios, e.g. 4‰ for δ2H and 0.4‰ for δ18O, probably resulting from isotope fractionation during dilution via the ConFlo interface. This method can be used to analyze nanoliter samples of water (e.g. 30 nL) with good precision of 0.5‰ for δ2H and 0.1‰ for δ18O. This is important for geosciences; for instance, fluid inclusions in ancient minerals may be analyzed for δ2H and δ18O to help understand the formation environments. Copyright © 2009 John Wiley & Sons, Ltd.
Comparison of collision‐ versus electron‐induced dissociation of Pt(II) ternary complexes of histidine‐ and methionine‐containing peptides
Authors: Feketeová Linda , Ryzhov Victor , O'Hair Richard A. J.
Published: August 2009

Incubation of the histidine‐containing peptides (GH, HG, GGH, GHG, HGG) and methionine‐containing peptides (GM, MG, GGM, GMG, MGG) with the platinum complexes [Pt(terpy)Cl]+ (A) and [Pt(dien)Cl]+ (B) followed by electrospray ionisation (ESI) led to a number of singly and doubly charged ternary platinum peptide complexes, including [Pt(L)M]2+ and [Pt(L)M–H]+ (where L = the ligand terpy or dien; M is a peptide). Each of the [Pt(L)M]2+ complexes was subjected to electron capture dissociation (ECD), collision‐induced dissociation (CID) and electron‐induced dissociation (EID), while each of the [Pt(L)M–H]+ complexes was subjected to CID and EID. Results from ECD suggest that the free electron is captured by the metal ion thus weakening the bonds to its ligands. In the case of the ligand terpy, which binds more strongly than dien, this weakening leads to the loss of the peptide. The minor products in the ECD spectra of [Pt(terpy)M]2+ complexes do show fragmentation along the peptide backbone, but the ions observed are of the a‐, b‐, and y‐type. For the complexes with methionine‐containing peptides, a marker ion, [Pt(L)SCH3]+, was found which is indicative of binding of Pt to the methionine side chain. For the histidine‐containing peptides, an ion containing platinum, the auxiliary ligand, and the histidine imine was observed in many instances, thus indicating the binding of the histidine side chain to the metal, but other modes of Pt coordination (N‐terminus) were also found to be competitive. These findings are consistent with a recent finding (Sze et al. J. Biol. Inorg. Chem. 2009; 14: 163) that Pt occupies the methionine‐rich copper(I)‐binding site rather than histidine‐rich copper(II)‐binding site in the CopC protein. Copyright © 2009 John Wiley & Sons, Ltd.
Molecular mechanisms mediated by human endogenous retroviruses (HERVs) in autoimmunity
Authors: Balada Eva , Ordi‐Ros Josep , Vilardell‐Tarrés Miquel
Published: August 2009

Eight per cent of the human genome is derived from the integration of retroviral sequences that were incorporated in our DNA more than 25 million years ago. Although some of these elements show mutations and deletions, some HERVs are transcriptionally active and produce functional proteins. Different mechanisms have been described which link HERVs to some chronic diseases such as several cancers, nervous system diseases and autoimmune rheumatic and connective tissue diseases. They could cause disease because of their capacity for being moved and inserted next to certain genes whose expression would be consequentially altered. Another way in which disease could potentially arise is when HERV‐encoded proteins are expressed. These proteins would be considered as [foreign] and they could trigger B‐cells to produce antibodies against them, which, in turn, might cross‐react with other proteins of our bodies. This mechanism could give rise to autoimmune diseases such as rheumatoid arthritis (RA), lupus erythematosus, Sjögren's syndrome (SJS), mixed connective tissue diseases and inflammatory neurological disease. Furthermore, it should be pointed out that HERV‐proteins may act as superantigens. Interestingly, some environmental agents seem to induce the expression of HERVs. Thus, ultraviolet light and several chemical agents could reactivate such sequences by altering their structure without modifying their nucleotide composition when the methylation pattern is changed. Therefore, the epigenetic changes observed in pathological conditions such as systemic lupus erythematosus (SLE) or cancer could be translated into an effect on the activation of some of the retroelements present in our genome which ultimately could have a direct or indirect role on the initiation and clinical evolution of certain chronic diseases. Copyright © 2009 John Wiley & Sons, Ltd.
The history of antiretrovirals: key discoveries over the past 25 years
Authors: De Clercq Erik
Published: August 2009

Within 25 years after zidovudine (3′‐azido‐2′,3′‐dideoxythymidine, AZT) was first described as an inhibitor of HIV replication, 25 anti‐HIV drugs have been formally approved for clinical use in the treatment of HIV infections: seven nucleoside reverse transcriptase inhibitors (NRTIs): zidovudine, didanosine, zalcitabine, stavudine, lamivudine, abacavir and emtricitabine; one nucleotide reverse transcriptase inhibitor (NtRTI): tenofovir [in its oral prodrug form: tenofovir disoproxil fumarate (TDF)]; four non‐nucleoside reverse transcriptase inhibitors (NNRTIs): nevirapine, delavirdine, efavirenz and etravirine; ten protease inhibitors (PIs): saquinavir, ritonavir, indinavir, nelfinavir, amprenavir, lopinavir, atazanavir, fosamprenavir, tipranavir and darunavir; one fusion inhibitor (FI): enfuvirtide; one co‐receptor inhibitor (CRI): maraviroc and one integrase inhibitor (INI): raltegravir. These compounds are used in various drug combination (some at fixed dose) regimens so as to achieve the highest possible benefit and tolerability, and to diminish the risk of virus‐drug resistance development. Copyright © 2009 John Wiley & Sons, Ltd.
Scientific discourse in three urban classrooms: The role of the teacher in engaging high school students in argumentation
Authors: McNeill Katherine L. , Pimentel Diane Silva
Published: August 2009

Argumentation is a core practice of science and has recently been advocated as an essential goal of science education. Our research focuses on the discourse in urban high school science classrooms in which the teachers used the same global climate change curriculum. We analyzed transcripts from three teachers' classrooms examining both the argument structure as well the dialogic interactions between students. Between 19% and 35% of the discourse focused on scientific argumentation in that students were using evidence and reasoning to justify their claims. Yet in terms of dialogic interactions, only one teacher's classroom was characterized by student‐to‐student interactions and students explicitly supporting or refuting the ideas presented by their peers. This teacher's use of open questions appeared to encourage students to construct and justify their claims using both their scientific and everyday knowledge. Furthermore, her explicit connections to previous students' comments appeared to encourage students to consider multiple views, reflect on their thinking and reflect on the thinking of their classmates. This study suggests that a teacher's use of open‐ended questions may play a key role in supporting students in argumentation in terms of both providing evidence and reasoning for students' claims and encouraging dialogic interactions between students. © 2009 Wiley Periodicals, Inc. Sci Ed 94:203–229, 2010
Stem Cell Activity in the Developing Human Cornea
Authors: Davies Sarah B. , Chui Jeanie , Madigan Michelle C. , Provis Jan M. , Wakefield Denis , Di Girolamo Nick
Published: August 2009

The adult cornea harbors stem cells (SCs) in its periphery, in a niche known as the limbus. Over the past 2 decades there has been substantial research into these adult corneal SCs, their limbal niche, and their therapeutic applications. However, few studies have investigated how this niche and its SCs develop in humans. To better characterize this development, human fetal corneas from 8.5- to 22-weeks'-gestation (n = 173), neonatal (n = 2), and adult (n = 10) specimens were obtained. Histological and immunohistochemical assessments were conducted to determine embryological changes and expression of developmental and SC-related genes. Fresh fetal corneas were explanted to propagate corneal progenitors and cells characterized using reverse transcription-polymerase chain reaction, immunohistochemistry, flow cytometry, and colony-forming assays. A novel “ridge-like” structure was identified, circumscribing the fetal cornea, which we hypothesize represents the rudimentary SC niche. Immunohistochemistry disclosed “stem-like” cells across the cornea, becoming confined to this ridge with increasing gestational age. In addition, for the first time, pure long-term cultures of fetal corneal epithelium, which displayed phenotypical and functional properties similar to those of adult limbal SCs, were established. Optimization of culture techniques and purification of this SC population will allow for further investigation of their proliferative ability, with potential research and clinical applications. This study expands our understanding of limbal niche development and opens new avenues for investigation.

Disclosure of potential conflicts of interest is found at the end of this article.
Testing with model checkers: a survey
Authors: Fraser Gordon , Wotawa Franz , Ammann Paul E.
Published: August 2009

About a decade after the initial proposal to use model checkers for the generation of test cases we take a look at the results in this field of research. Model checkers are formal verification tools, capable of providing counterexamples to violated properties. Normally, these counterexamples are meant to guide an analyst when searching for the root cause of a property violation. They are, however, also very useful as test cases. Many different approaches have been presented, many problems have been solved, yet many issues remain. This survey paper reviews the state of the art in testing with model checkers. Copyright © 2008 John Wiley & Sons, Ltd.
A systems integration framework for process analysis and improvement
Authors: Jain Rashmi , Chandrasekaran Anithashree , Erol Ozgur
Published: August 2009

Systems Integration (SI) is an important element of Systems Engineering. It involves the integration of hardware, software, products, services, processes, and humans. The ever‐increasing scale of complexity of systems and its impact on the business requires that we revisit the processes involved in the development and integration of a system. This paper proposes a Systems Integration Process Model (SIPM) based on a comprehensive lifecycle view of systems integration. As part of the ongoing SI research at Stevens Institute of Technology, the authors have developed a Systems Integration Framework (SIF) which incorporates the relevant aspects of integration from a lifecycle perspective and sets a foundation to an end‐to‐end approach to SI. Our end‐to‐end approach focuses on how integration issues can be addressed up‐front to minimize integration related complexities and challenges later on in the system engineering process. This paper discusses the merits and benefits of applying the SIPM to evaluate and improve current SI processes in organizations. The paper provides, in addition to an overview of the SI framework, the activities included in the model. The model was pilot tested to evaluate the SI processes at a government agency. The results were used to provide recommendations for SI process reengineering. © 2009 Wiley Periodicals, Inc. Syst Eng
Unintended consequences of performance specifications for the reliability of military weapon systems
Authors: Kujawski Edouard
Published: August 2009

The use of performance specifications became a key US Department of Defense (DoD) acquisition reform in the 1990s. Gone were the detailed military specifications for parts and materials selection, workmanship, derating, and fault tolerance. Maximum use was to be made of commercial specs. Reliability would be specified only in quantitative terms such as Mean‐Time‐To‐Failure (MTTF) and/or the reliability R(t). However, there are significant differences between commercial and military weapon systems whereby performance specifications might bring in significantly greater mission risk. Reliability data from 1996 to 2000 might be an indicator of negative unintended consequences of the cancellation of military specifications. The acquisition of successful military systems requires a mix of performance and prescriptive reliability requirements that depend on the application, technology maturity, and complexity. © 2009 Wiley Periodicals, Inc. Syst Eng
Persistent Photoconductivity Studies in Nanostructured ZnO UV Sensors
Authors: Hullavarad Shiva , Hullavarad Nilima , Look David , Claflin Bruce
Published: August 2009

The phenomenon of persistent photoconductivity is elusive and has not been addressed to an extent to attract attention both in micro and nanoscale devices due to unavailability of clear material systems and device configurations capable of providing comprehensive information. In this work, we have employed a nanostructured (nanowire diameter 30–65 nm and 5 μm in length) ZnO-based metal–semiconductor–metal photoconductor device in order to study the origin of persistent photoconductivity. The current–voltage measurements were carried with and without UV illumination under different oxygen levels. The photoresponse measurements indicated a persistent conductivity trend for depleted oxygen conditions. The persistent conductivity phenomenon is explained on the theoretical model that proposes the change of a neutral anion vacancy to a charged state.
A simple approach for mouse embryonic stem cells isolation and differentiation inducing embryoid body formation
Authors: Fagundez Carol B. , Loresi Mónica A. , Quintana Ojea Marcos E. , Delcourt Stella M. , Testa Roberto , Gogorza Sebastián J. , Argibay Pablo F.
Published: August 2009

Stem cells were derived from hatched blastocyst‐stage mouse embryos of the C57BL/6 strain employing a knockout serum replacement instead of the traditional fetal calf serum, thereby avoiding the use of immunosurgery. Although fetal calf serum was not good for isolation of stem cells, a combination of this serum plus knockout serum increased the expansion rate of the cell culture. The derived cells were capable of maintaining an undifferentiated state during several passages, as demonstrated by the presence of alkaline phosphatase activity, stage‐specific embryonic antigen 1 (SSEA‐1), and octamer binding protein 4 (Oct‐4). Suspension culture in bacteriological dishes gave better results than the hanging drop method for differentiation by means of embryoid body formation. Mouse embryonic stem cells showed spontaneous differentiation into derivatives of the 3 germ layers in culture media supplemented with fetal calf serum but not with knockout serum.
Effects of an endothelial cell‐conditioned medium on the hematopoietic and endothelial differentiation of embryonic stem cells
Authors: Sun Xuan , Cheng Lamei , Duan Huaxin , Lu Guangxiu
Published: August 2009

We have examined the effect of mouse bone marrow endothelial cell‐conditioned medium (mEC‐CM) on hematopoietic and endothelial differentiation of mouse embryonic stem cells (mESCs). mEC‐CM can efficiently promote the differentiation of mESCs into Flk+ cells and hematopoietic colony‐forming cells. mEC‐CM proved to be as potent as a cytokine cocktail comprised of VEGF, bFGF, IGF and EGF. After inducing mESCs with mEC‐CM, cobblestone‐like cells were mechanically selected and identified which had the ability to incorporate DiI‐Ac‐LDL. DiI‐Ac‐LDL‐positive cells were endothelial‐like cells due to their expression of CD31 and Flk1, ability to bind to UEA1 and capacity to form capillary‐like tube structures on matrigel. In conclusion, mEC‐CM can efficiently promote the differentiation of mESCs into endothelial cells and hematopoietic colony‐forming cells. The differentiated endothelial‐like cells can be isolated by using DiI‐Ac‐LDL labeling and mechanical selection.
Possible association between attention deficit hyperactivity disorder and attempted suicide in adolescents – A pilot study
Authors: Manor I. , Gutnik I. , Ben-Dor D.H. , Apter A. , Sever J. , Tyano S. , Weizman A. , Zalsman G.
Published: August 2009

Objective

Both adolescent suicide and attention deficit hyperactivity disorder (ADHD) are troubling phenomena with high comorbidity, including impulsivity, depression and personality disorders (PD). Studies on the association between these two phenomena are relatively rare. This pilot study's aim was to estimate the rate of ADHD in adolescents attempting suicide.

Method

Subjects constituted consecutive admissions to the psychiatric emergency room (ER) who were admitted as a result of attempting suicide. Assessment included the use of the Kiddie-SADS, Strengths and Difficulties Questionnaire (SDQ) and the Conners’ Rating Scale (CRS). Those diagnosed as suffering from ADHD were assessed by a standardized Continuous Performance Test (Test of Variables of Attention [TOVA]) that included methylphenidate (MPH) challenge. Twenty-three (23) adolescents completed the study. M:F ratio was 5:18, respectively.

Results

Of the 23 participants who completed the study, 65% were diagnosed with ADHD, 43.5% with depression and 39% with cluster B PD. ADD/ADHD ratio was 66%:34%. Only five of the patients were formerly diagnosed as ADHD, only three had been medicated and 14 out of 15 adolescents responded well to MPH challenge.

Conclusion

These preliminary results suggest a significant association between ADHD and suicidal behavior in adolescents. Further study is needed to establish this association and assess the causality.
Psychopathology and personality traits in psychotic patients and their first-degree relatives
Authors: Cortés M.J. , Valero J. , Gutiérrez-Zotes J.A. , Hernández A. , Moreno L. , Jariod M. , Martorell L. , Vilella E. , Labad A.
Published: August 2009

Personality dimensions have been associated with symptoms dimensions in schizophrenic patients (SP). In this paper we study the relationships between symptoms of functional psychoses and personality dimensions in SP and their first-degree relatives (SR), in other psychotic patients (PP) and their first-degree relatives (PR), and in healthy controls in order to evaluate the possible clinical dimensionality of these disorders. Twenty-nine SP, 29 SR, 18 PP, 18 PR and 188 controls were assessed using the temperament and character inventory (TCI-R). Current symptoms were evaluated with positive and negative syndrome scale (PANSS) using the five-factor model described previously (positive [PF], negative [NF], disorganized [DF], excitement [EF] and anxiety/depression [ADF]). Our TCI-R results showed that patients had different personality dimensions from the control group, but in relatives, these scores were not different from controls. With regard to symptomatology, we highlight the relations observed between harm avoidance (HA) and PANSS NF, and between self-transcendence (ST) and PANSS PF. From a personality traits-genetic factors point of view, schizophrenia and other psychosis may be initially differentiated by temperamental traits such as HA. The so-called characterial traits like ST would be associated with the appearance of psychotic symptoms.
A multi-proxy paleolimnological reconstruction of Holocene climate conditions in the Great Basin, United States
Authors: Reinemann Scott A. , Porinchu David F. , Bloom Amy M. , Mark Bryan G. , Box Jason E.
Published: August 2009

A sediment core spanning ∼ 7000 cal yr BP recovered from Stella Lake, a small sub-alpine lake located in Great Basin National Park, Nevada, was analyzed for subfossil chironomids (non-biting midges), diatoms, and organic content (estimated by loss-on-ignition (LOI)). Subfossil chironomid analysis indicates that Stella Lake was characterized by a warm, middle Holocene, followed by a cool “Neoglacial” period, with the last two millennia characterized by a return to warmer conditions. Throughout the majority of the core the Stella Lake diatom-community composition is dominated by small, periphytic taxa which are suggestive of shallow, cool, alkaline, oligotrophic waters with extensive seasonal ice cover. A reconstruction of mean July air temperature (MJAT) was developed by applying a midge-based inference model for MJAT (two-component WA-PLS) consisting of 79 lakes and 54 midge taxa (rjack2= 0.55, RMSEP = 0.9°C). Comparison of the chironomid-inferred temperature record to existing regional paleoclimate reconstructions suggests that the midge-inferred temperatures correspond well to regional patterns. This multi-proxy record provides valuable insight into regional Holocene climate and environmental conditions by providing a quantitative reconstruction of peak Holocene warmth and aquatic ecosystem response to these changes in the Great Basin, a region projected to experience increased aridity and higher temperatures.
Scientific travel in the Atlantic world: the French expedition to Gorée and the Antilles, 1681–1683
Authors: DEW NICHOLAS
Published: August 2009

Although historians have long recognized the importance of long-range scientific expeditions in both the practice and culture of eighteenth- and nineteenth-century science, it is less well understood how this form of scientific organization emerged and became established in the seventeenth and early eighteenth centuries. In the late seventeenth century new European scientific institutions tried to make use of globalized trade networks for their own ends, but to do so proved difficult. This paper offers a case history of one such expedition, the voyage sponsored by the French Académie royale des sciences to Gorée (in modern Senegal) and the Caribbean islands of Guadeloupe and Martinique in 1681–3. The voyage of Varin, Deshayes and de Glos reveals how the process of travel itself caused problems for instruments and observers alike.
Brain neural activity patterns yielding numbers are operators, not representations
Authors: Freeman Walter J. , Kozma Robert
Published: August 2009

We contrapose computational models using representations of numbers in parietal cortical activity patterns (abstract or not) with dynamic models, whereby prefrontal cortex (PFC) orchestrates neural operators. The neural operators under PFC control are activity patterns that mobilize synaptic matrices formed by learning into textured oscillations we observe through the electroencephalogram from the scalp (EEG) and the electrocorticogram from the cortical surface (ECoG). We postulate that specialized operators produce symbolic representations existing only outside of brains.
Slippery platform: The role of automatic and intentional processes in testing the effect of notation
Authors: Algom Daniel
Published: August 2009

The type of processing of numerical dimensions varies greatly and is governed by context. Considering this flexibility in tandem with a fuzzy demarcation line between automatic and intentional processes, it is suggested that testing the effect of notation should not be confined to automatic processing, in particular to passive viewing. Recent behavioral data satisfying the authors' stipulations reveal a considerable, though perhaps not exclusive, core of common abstract processing.
Symbols in numbers: From numerals to magnitude information
Authors: Lindemann Oliver , Rueschemeyer Shirley-Ann , Bekkering Harold
Published: August 2009

A dual-code model of number processing needs to take into account the difference between a number symbol and its meaning. The transition of automatic non-abstract number representations into intentional abstract representations could be conceptualized as a translation of perceptual asemantic representations of numerals into semantic representations of the associated magnitude information. The controversy about the nature of number representations should be thus related to theories on embodied grounding of symbols.
Abstract after all? Abstraction through inhibition in children and adults
Authors: Houdé Olivier
Published: August 2009

I challenge two points in Cohen Kadosh & Walsh's (CK & W) argument: First, the definition of abstraction is too restricted; second, the distinction between representations and operations is too clear-cut. For example, taking Jean Piaget's “conservation of number task,” I propose that another way to avoid orthodoxy in the field of numerical cognition is to consider inhibition as an alternative idea of abstraction.
Non-abstractness as mental simulation in the representation of number
Authors: Myachykov Andriy , Platenburg Wouter P. A. , Fischer Martin H.
Published: August 2009

Abstraction is instrumental for our understanding of how numbers are cognitively represented. We propose that the notion of abstraction becomes testable from within the framework of simulated cognition. We describe mental simulation as embodied, grounded, and situated cognition, and report evidence for number representation at each of these levels of abstraction.
Abstract or not? Insights from priming
Authors: Reynvoet Bert , Notebaert Karolien
Published: August 2009

Cohen Kadosh & Walsh (CK&W) argue that numerical representation is primarily non-abstract. However, in their target article they failed to consider recent behavioral priming experiments. These priming experiments provide evidence for an abstract numerical representation under automatic conditions.
Numerical representations: Abstract or supramodal? Some may be spatial
Authors: Vallar Giuseppe , Girelli Luisa
Published: August 2009

The target article undermines the existence of a shared unitary numerical format, illustrating a variety of representations. The “abstract”/“not-abstract” dichotomy does not capture their specific features. These representations are “supramodal” with respect to the sensory modality of the stimulus, and independent of its specific notation, with a main role of spatial codes, both related and unrelated to the mental number line.
Numerical representation in the parietal lobes: Abstract or not abstract?
Authors: Cohen Kadosh Roi , Walsh Vincent
Published: August 2009

The study of neuronal specialisation in different cognitive and perceptual domains is important for our understanding of the human brain, its typical and atypical development, and the evolutionary precursors of cognition. Central to this understanding is the issue of numerical representation, and the question of whether numbers are represented in an abstract fashion. Here we discuss and challenge the claim that numerical representation is abstract. We discuss the principles of cortical organisation with special reference to number and also discuss methodological and theoretical limitations that apply to numerical cognition and also to the field of cognitive neuroscience in general. We argue that numerical representation is primarily non-abstract and is supported by different neuronal populations residing in the parietal cortex.
To enhance transparency of a piezo-actuated tele-micromanipulator using passive bilateral control
Authors: Seifabadi R. , Rezaei S. M. , Ghidary S. Shiry , Zareinejad M. , Saadat M.
Published: August 2009

This paper presents the research work on a 1 degree of freedom (DOF) force reflecting tele-micromanipulation system. This system enables a human operator to position remote objects very precisely having haptic feedback. The slave robot is a nano-positioning piezo-actuator with hysteretic dynamics. This intrinsic nonlinearity results in positioning inaccuracy and instability. Hence, a LuGre friction model is employed to model and compensate for this undesirable behavior. By means of a transformation, the 2-DOF master–slave system (1-DOF each) is decomposed into two 1-DOF new systems: the shape system, representing the master–slave position coordination, and the locked system, representing dynamics of the coordinated system. A key innovation of this paper is to generalize this approach to the hysteresis-type nonlinear teleoperated systems. For the shape system, a position tracking controller is designed in order to achieve position coordination. This position coordination is guaranteed not only in free space motion, but also during contact at the slave side. Furthermore, a force tracking controller is designed for the locked system in order to achieve tracking of the force exerted on the master and slave robots. Using this force controller, transparency is remarkably enhanced. Based on the virtual flywheels concept, passivity of the closed-loop teleoperator is guaranteed against dynamic parameter uncertainties and force measurement inaccuracies. The simulation and experimental results verify the capability of the proposed control architectures in achieving high-level tracking of the position and force signals while the system remains stable.
Robotic surgery: from autonomous systems to intelligent tools
Authors: Rodriguez y Baena Ferdinando , Davies Brian
Published: August 2009

A brief history of robotic surgery is provided, which describes the transition from autonomous robots to hands-on systems that are under the direct control of the surgeon. An example of the latter is the Acrobot (for active-constraint robot) system used in orthopaedics, whilst soft-tissue surgery is illustrated by the daVinci telemanipulator system. Non-technological aspects of robotic surgery have often been a major impediment to their widespread clinical use. These are discussed in detail, together with the role of navigation systems, which are considered a major competitor to surgical robots. A detailed description is then given of a registration method for robots to achieve improved accuracy. Registration is a major source of error in robotic surgery, particularly in orthopaedics. The paper describes the design and clinical implementation of a novel method, coined the bounded registration method, applied to minimally invasive registration of the femur. Results of simulations which compare the performance of bounded registration with a standard implementation of the iterative closest point algorithm are also presented, alongside a description of their application in the Acrobot hands-on robot, used clinically for uni-condylar knee arthroplasty.
Rod bipolar cells in the retina of the capuchin monkey (Cebus apella): Characterization and distribution
Authors: LAMEIRÃO SORAIA VALÉRIA O.C. , HAMASSAKI DANIA E. , RODRIGUES ANDERSON R. , DE LIMA SILENE MARIA A. , FINLAY BARBARA L. , SILVEIRA LUIZ CARLOS L.
Published: August 2009

Rod bipolar cells inCebus apellamonkey retina were identified by an antibody against the alpha isoform of protein kinase C (PKCα), which has been shown to selectively identify rod bipolars in two other primates and various mammals. Vertical sections were used to confirm the identity of these cells by their characteristic morphology of dendrites and axons. Their topographic distribution was assessed in horizontal sections; counts taken along the dorsal, ventral, nasal, and temporal quadrants. The density of rod bipolar cells increased from 500 to 2900 cells/mm2at 1 mm from the fovea to reach a peak of 10,000–12,000 cells/mm2at 4 mm, approximately 5 deg of eccentricity, and then gradually decreased toward retinal periphery to values of 5000 cells/mm2or less. Rod to rod bipolar density ratio remained between 10 and 20 across most of the retinal extension. The number of rod bipolar cells per retina was 6,360,000 ± 387,433 (mean ±s.d.,n= 6). The anti-PKCα antibody has shown to be a good marker of rod bipolar cells ofCebus, and the cell distribution is similar to that described for other primates. In spite of the difference in the central retina, the density variation of rod bipolar cells in theCebusandMacacaas well as the convergence from rod to rod bipolar cells are generally similar, suggesting that both retinae stabilize similar sensitivity (as measured by rod density) and convergence.
Reliability of a novel paradigm for determining hemispheric lateralization of visuospatial function
Authors: WHITEHOUSE ANDREW J. O. , BADCOCK NICHOLAS , GROEN MARGRIET A. , BISHOP DOROTHY V. M.
Published: August 2009

In most individuals, language production and visuospatial skills are subserved predominantly by the left and right hemispheres, respectively. Functional Transcranial Doppler (fTCD) provides a noninvasive and relatively low-cost method for measuring functional lateralization. However, while the silent word generation task provides an accurate and reliable paradigm for investigating lateralization of language production, there is no comparable gold-standard method for measuring visuospatial skills. Thirty undergraduate students (19 females) completed a task of spatial memory while undergoing fTCD recording. Participants completed this task at two different time points, separated by between 26 to 155 days. The relative activation between hemispheres averaged across all participants was found to be consistent across testing sessions. This was observed at the individual level also, with a quantitative index of lateralization showing high reproducibility. These findings indicate that the use of the spatial memory task with fTCD is a robust methodology for examining laterality of visuospatial skills. (JINS, 2009, 15, 1028–1032.)
Examining the multifactorial nature of cognitive aging with covariance analysis of positron emission tomography data
Authors: SIEDLECKI KAREN L. , HABECK CHRISTIAN G. , BRICKMAN ADAM M. , GAZES YUNGLIN , STERN YAAKOV
Published: August 2009

Research has indicated that there may be age-related and Alzheimer’s disease (AD) -related reductions in regional cerebral blood flow (rCBF) in the brain. This study explored differences in age- and AD-related rCBF patterns in the context of cognitive aging using a multivariate approach to the analysis of H215O PET data. First, an rCBF covariance pattern that distinguishes between a group of younger and older adults was identified. Individual subject’s expression of the identified age-related pattern was significantly correlated with their performance on tests of memory, even after controlling for the effect of age. This finding suggests that subject expression of the covariance pattern explained additional variation in performance on the memory tasks. The age-related covariance pattern was then compared to an AD-related covariance pattern. There was little evidence that the two covariance patterns were similar, and the age-related pattern did a poor job of differentiating between cognitively-healthy older adults and those with probable AD. The findings from this study are consistent with the multifactorial nature of cognitive aging. (JINS, 2009, 15, 973–981.)
Compositional and Structural Study of a (K0.5Na0.5)NbO3 Single Crystal Prepared by Solid State Crystal Growth
Authors: Benčan Andreja , Tchernychova Elena , Godec Matjaž , Fisher John , Kosec Marija
Published: August 2009

In this work we investigated the chemical composition and structure of (K0.5Na0.5)NbO3 (KNN) single crystals grown by the solid state crystal growth method. The optical, scanning, and transmission electron microscopies were employed for the analysis of the chemical homogeneity and domain structure of the KNN crystal. No compositional inhomogeneities within experimental error were encountered in the KNN single crystals. The domain structure of the KNN single crystal, with a monoclinic unit cell, is composed of large 90° domains of up to 100 μm width, which further consist of smaller 180° domains with widths from 50 to 300 nm.
The Role of Interleukin-6 in the Formation of the Coronary Vasculature
Authors: Banerjee Indroneal , Fuseler John W. , Souders Colby A. , Bowers Stephanie L.K. , Baudino Troy A.
Published: August 2009

The formation and the patterning of the coronary vasculature are critical to the development and pathology of the heart. Alterations in cytokine signaling and biomechanical load can alter the vascular distribution of the vessels within the heart. Changes in the physical patterning of the vasculature can have significant impacts on the relationships of the pressure-flow network and distribution of critical growth and survival factors to the tissue. Interleukin-6 (IL-6) is a pleiotropic cytokine that regulates several biological processes, including vasculogenesis. Using both immunohistological and cardioangiographic analyses, we tested the hypothesis that IL-6-loss will result in decreased vessel density, along with changes in vascular distribution. Moreover, given the impact of vascular patterning on pressure-flow and distribution mechanics, we utilized non-Euclidean geometrical fractal analysis to quantify the changes in patterning resulting from IL-6-loss. Our analyses revealed that IL-6-loss results in a decreased capillary density and increase in intercapillary distances, but does not alter vessel size or diameter. We also observed that the IL-6−/− coronary vasculature had a marked increase in fractal dimension (D value), indicating that IL-6-loss alters vascular patterning. Characterization of IL-6-loss on coronary vasculature may lend insight into the role of IL-6 in the formation and patterning of the vascular bed.
Three-Dimensional X-Ray Imaging and Analysis of Fungi on and in Wood
Authors: Van den Bulcke Jan , Boone Matthieu , Van Acker Joris , Van Hoorebeke Luc
Published: August 2009

As wood is prone to fungal degradation, fundamental research is necessary to increase our knowledge aiming at product improvement. Several imaging modalities are capable of visualizing fungi, but the X-ray equipment presented in this article can envisage fungal mycelium in wood nondestructively in three dimensions with submicron resolution. Four types of wood subjected to the action of the white rot fungusCoriolus versicolor(Linnaeus) Quélet (CTB 863 A) were scanned using an X-ray-based approach. Comparison of wood volumes before and after fungal exposure, segmented manually or semiautomatically, showed the presence of the fungal mass on and in the wood samples and therefore demonstrated the usefulness of computed X-ray tomography for mycological and wood research. Further improvements to the experimental setup are necessary to resolve individual hyphae and enhance segmentation.
X-Ray Microtomography Studies of Tannin-Derived Organic and Carbon Foams
Authors: Tondi G. , Blacher S. , Léonard A. , Pizzi A. , Fierro V. , Leban J.M. , Celzard A.
Published: August 2009

Tannin-based rigid foams of different bulk densities and their carbonized counterparts were investigated for the first time by X-ray microtomography. This method allowed acquisition of three-dimensional pictures of such highly porous materials. Through mathematical treatment of the images, extremely useful physical characteristics such as porosity, fraction of open cells, connectivity, tortuosity, and pore-size distribution were determined as a function of the foam's density. The obtained information was compared with independent data derived from pycnometry measurements and scanning electron microscope image analysis. The agreement was shown to be acceptable in the limit of the accuracy of the laboratory microtomograph (4 μm). Moreover, recalculating properties like permeability were shown to be quite possible based on the results of standard microtomography data.
Northward interplanetary magnetic field plasma sheet entropies
Authors: Johnson Jay R. , Wing Simon
Published: August 2009

The plasma sheet pressure, temperature, and density profiles inferred from DMSP observations are used to investigate northward interplanetary magnetic field plasma sheet specific entropy s = p/ργ or p/nγ (for a single ion species). Profiles of s for hot and cold populations are considered. The hot ion population s profile suggests a duskward heat flux that is consistent with the curvature and gradient drift. In contrast, s of the cold population is approximately conserved in the X direction but has a strong gradient toward the midnight meridian. The total entropy (S = ∫p1/γ dl/B) and s under various entry mechanisms are estimated for comparisons with observed values. The cold population s is higher than that of the magnetosheath, suggesting the entry process may heat the ions. Cusp reconnection by itself may not increase the magnetosheath ion s, but cusp reconnection with kinetic Alfvén waves (KAW) may provide the necessary heating. Localized reconnection in Kelvin‐Helmholtz vortices may increase s if the plasma expands nonadiabatically into the large magnetospheric flux tube volume. KAWs may lead to diffusion and heating consistent with the observations. The cold population s increases by a factor of 5 from the flanks to the midnight meridian, which provides a constraint for transport mechanism(s) within the plasma sheet. A simple calculation is performed to demonstrate that the spatial gradients of s in the plasma sheet could result from the temporal dependence of transport processes in the magnetopause boundary layer.
Spatial structures and statistics of atmospheric gravity waves derived using a heuristic vertical cross‐section extraction from COSMIC GPS radio occultation data
Authors: Horinouchi Takeshi , Tsuda Toshitaka
Published: August 2009

A number of studies have investigated atmospheric gravity waves (GWs) using temperature profiles from GPS radio occultation (RO). This study is the first to report the horizontal structures of GWs obtained directly by using multiple profiles based on the GPS RO data from the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC)/FORMOSAT‐3 mission. It was found that the horizontal locations of profiles obtained from successive passages of multiple COSMIC satellites were frequently aligned quasi‐linearly over distances of around 1500–5000 km. Therefore, almost instantaneous (within 1 h) snapshots of vertical‐horizontal cross sections of atmospheric temperature could be obtained. Clear GW features over multiple occultations were identified in many of the cross sections. It was indicated from a statistical analysis that horizontal wavelengths of GWs in the winter (here northern) hemisphere were generally smaller than those in the equatorial region or in the other hemisphere. A positive skewness was found in the probability distribution of the GW amplitude in middle to high latitudes, while the distribution was not skewed in low latitudes. GWs in the northern midlatitudes were studied further. In the zonal direction, both eastward and westward propagations relative to background winds were identified. The GW amplitude had a negative correlation with zonal wind shear. In the meridional direction, northward propagation was dominant, indicating that the dominant source region of meridionally propagating GWs was in the subtropics.
Simulation of the eastward 4‐day wave in the Antarctic winter mesosphere using a gravity wave resolving general circulation model
Authors: Watanabe Shingo , Tomikawa Yoshihiro , Sato Kaoru , Kawatani Yoshio , Miyazaki Kazuyuki , Takahashi Masaaki
Published: August 2009

The eastward moving 4‐day wave in the Antarctic winter mesosphere is investigated using a high‐resolution middle atmosphere general circulation model that directly simulates the spontaneous generation, propagation, and dissipation of gravity waves. The results are also compared with the simulated seasonal march of the meridional structures of the westerly jet streams in the Southern Hemisphere upper stratosphere and mesosphere in order to investigate baroclinic/barotropic instability as a possible excitation mechanism for the 4‐day wave. The model successfully reproduces the dynamically unstable double‐jet structure of the mesospheric westerly winds. The simulated 4‐day wave develops in association with the baroclinic and barotropic instability of the mesospheric mean flows and has similar characteristics to those observed at 50–60°S near the stratopause. The 4‐day wave has strong equatorward heat flux associated with strong baroclinicity in the Antarctic winter mesosphere, mainly attributable to poleward overturning circulation driven by gravity wave forcing. Eastward forcing due to the 4‐day wave occurs within the double‐jet structure and offsets part of the westward forcing due to gravity waves. Such an effect partially acts to stabilize the unstable mean flow structure in the Antarctic winter mesosphere.