bluuebunny/crossref_metadata_2025 huggingface dataset:
Neuronal gene expression correlates of Parkinson's disease with dementia
Authors: Stamper Chelsea , Siegel Andrew , Liang Winnie S. , Pearson John V. , Stephan Dietrich A. , Shill Holly , Connor Don , Caviness John N. , Sabbagh Marwan , Beach Thomas G. , Adler Charles H. , Dunckley Travis
Published: July 2008

Dementia is a common disabling complication in patients with Parkinson's disease (PD). The underlying molecular causes of Parkinson's disease with dementia (PDD) are poorly understood. To identify candidate genes and molecular pathways involved in PDD, we have performed whole genome expression profiling of susceptible cortical neuronal populations. Results show significant differences in expression of 162 genes (P < 0.01) between PD patients who are cognitively normal (PD‐CogNL) and controls. In contrast, there were 556 genes (P < 0.01) significantly altered in PDD compared to either healthy controls or to PD‐CogNL cases. These results are consistent with increased cortical pathology in PDD relative to PD‐CogNL and identify underlying molecular changes associated with the increased pathology of PDD. Lastly, we have identified expression differences in 69 genes in PD cortical neurons that occur before the onset of dementia and that are exacerbated upon the development of dementia, suggesting that they may be relevant presymptomatic contributors to the onset of dementia in PD. These results provide new insights into the cortical molecular changes associated with PDD and provide a highly useful reference database for researchers interested in PDD. © 2008 Movement Disorder Society
Poor dopaminergic response of impaired dexterity in Parkinson's disease: Bradykinesia or limb kinetic apraxia?
Authors: Gebhardt Andreas , Vanbellingen Tim , Baronti Fabio , Kersten Bernd , Bohlhalter Stephan
Published: July 2008

Patients with Parkinson's disease (PD) often show impaired manual dexterity even when being only minimally bradykinetic, suggesting that they may have limb kinetic apraxia (LKA), that is, a loss of fine motor skill not explained by elemental motor deficits. To explore this dissociation, we investigated the differential dopaminergic responsiveness of dexterity and bradykinesia in PD. Twelve patients with PD (4 women, age 64.4 ± 8.3, mean + SD) and 12 matched healthy controls (64.8 ± 8.9) were tested twice in ON vs. OFF and 1st vs. 2nd trial, respectively. A coin rotation (CR) task was applied to assess dexterity and a finger tapping (FT) task to assess bradykinesia. Performance was followed by video recording and analyzed by measuring the frequency of CR and FT during three 10‐second periods. Statistical analysis was done by a mixed factorial design with group (PD vs. controls) as between‐subject factor and medication (ON‐ vs. OFF‐state or 1st vs. 2nd trial), task (FT vs. CR), and handedness (dominant vs. nondominant) as within‐subject factors. In patients with PD, regardless of hand involved, dopaminergic treatment only mildly improved CR performance, in contrast to the strong increase in FT scores (up to the level of controls), as demonstrated by the significant triple interaction of the factors group, medication, and task (F1,22 = 7.9, P = 0.01; η2 = 0.26). Furthermore, CR scores were considerably lower, both in OFF and ON, than in normal controls, pointing to a substantial impairment of dexterity in PD (P < 0.001). In conclusion, impaired manual dexterity showing significantly diminished response to dopaminergic treatment suggests that dextrous deficits in PD are related to LKA rather than bradykinesia. © 2008 Movement Disorder Society
Parallel generation of initial element assemblies for two‐dimensional discrete element simulations
Authors: Zsaki A. M.
Published: July 2008

The discrete element method (DEM) enables modeling of the behavior of granular materials and rock masses via the interaction of elements, as the whole model deforms under the applied loading. As a starting point of any DEM simulation, the computational domain needs to be filled with discrete elements. Disks are often used for 2D simulations to generate the model. There are techniques developed to fill a domain with disks, but some of them take considerable time, comparable to the DEM simulation itself. This article presents a parallel algorithm that can fill domains with a tight packing of disks. The algorithm is scalable and its implementation was tested on both a shared memory parallel computer and a multiprocessor, multicore workstation. The applicability of the algorithm in filling domains with disks is demonstrated on a practical example of ore flow at a drawpoint in mining. Copyright © 2008 John Wiley & Sons, Ltd.
‘Where are we now?’ A process for evaluating the context of care in practice development
Authors: Boomer Christine , McCormack Brendan
Published: July 2008

This is the second article in which we share the processes used during the action cycles of a collaborative practice development (PD) programme with the focus of developing clinical nurse leaders to develop practice. The focus for this particular action cycle of the programme was ‘changes to clinical care received by service users and to the context of care delivery’. This article presents an overview of the activity cycles that took place to enable the clinical leaders to evaluate culture, context and existing practice in their units, and then to move practice forward towards their visions for the future.

The activities initiated and employed in this PD programme have enabled the participating clinical leaders to evaluate practice, and identify and implement practice changes in a bid to move towards transforming the culture and context of care in their individual practice setting. Copyright © 2008 John Wiley & Sons, Ltd.
Viscoelastic behavior of epoxy prepolymer/organophilic montmorillonite dispersions
Authors: Solar Lorena , Nohales Andrés , Muñoz‐Espí Rafael , López Daniel , Gómez Clara M.
Published: July 2008

Dispersions of a bisphenol A‐based epoxy resin with an organophilic montmorillonite (Nanofil 919) were studied by X‐ray diffraction and oscillatory shear rheometry. X‐ray studies reveal that the clay is intercalated by the epoxy and forms stable dispersions. The viscoelastic behavior of the nanodispersions was measured as a function of the Nanofil concentration and temperature. An increase in both G′ and G″ moduli was detected as the concentration increases. Furthermore, a transition from a liquid‐like behavior, at low temperatures, to a solid‐like behavior, at higher temperatures, was observed for all the samples. This transition is accounted for the formation of a percolated structure of interconnected tactoids through hydrophobic interactions. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1837–1844, 2008
Factors with independent influence on the ‘timed up and go’ test in patients with hip fracture
Authors: Kristensen Morten Tange , Foss Nicolai Bang , Kehlet Henrik
Published: July 2008

Background and Purpose. Data on performance times for the ‘timed up and go’ (TUG) test with analyses of factors, that eventually could affect the result in patients with hip fracture, have not been published to date. The aims of the present study, therefore, were to assess normative reference values of TUG performances and determine the influence of individual and clinical factors on TUG‐test scores in patients with hip fracture. Method. In this prospective, descriptive study, a total of 196 consecutive patients over the age of 60, and able to perform the TUG when discharged directly to their own homes from a specialized orthopaedic hip fracture unit, were evaluated. The association between TUG scores and categorical variables were examined, and linear regression was used to investigate the factors influencing performance times. Results. Univariate analysis showed significant differences between all categorical variables, except gender, but multivariate linear regression analyses showed that only a high pre‐fracture function level, evaluated by the New Mobility Score (B = −11), was independently associated with having a good TUG score, while older age (B = 0.49), having an intertrochanteric fracture (B = 7), performing TUG with a walker (B = 15), and performing TUG in the later postoperative period (B = 0.39) were independently associated with having a poorer TUG score. Conclusions. These preliminary normative reference values of TUG performances in patients with hip fracture can be used as references, to which individuals can expect to perform. Multivariate testing suggests that clinicians should use age, pre‐fracture function, fracture type and walking‐aid specific data when interpreting the TUG test results. Physiotherapists should be aware of this if TUG scores are to be used predictively or as an outcome measure in patients with hip fracture, especially in research. Copyright © 2008 John Wiley & Sons, Ltd.
Quantitatively resolving mixtures of isobaric compounds using chemical ionization mass spectrometry by modulating the reactant ion composition
Authors: Fortner E. C. , Knighton W. B.
Published: July 2008

Acrolein (C3H4O) and 1‐butene (C4H8) can both be individually detected by proton transfer chemical ionization mass spectrometry (CI‐MS). However, because these compounds are isobaric, mixtures of these two compounds cannot be resolved since both compounds react with H3O+ via a proton‐transfer reaction to form a protonated molecule that is detected at a nominal mass‐to‐charge ratio of 57 (m/z 57). While both compounds react with H3O+ only acrolein reacts to any significant extent with H3O+(H2O). Recognizing that the electrical potential applied to a drift tube reaction mass spectrometer provides a simple and effective means for varying the relative intensity of the H3O+ and H3O+(H2O) reactant ions we have developed a method whereby we make use of this reactivity difference to resolve mixtures of these two compounds. We demonstrate a technique where the individual contributions of acrolein and 1‐butene within a mixture can be quantitatively resolved by systematically changing the reagent ion from H3O+ to H3O+(H2O) through control of the electric potential applied to the drift tube reaction region of a proton transfer reaction mass spectrometer. Copyright © 2008 John Wiley & Sons, Ltd.
Trace analysis of dithiocarbamate fungicide residues on fruits and vegetables by hydrophilic interaction liquid chromatography/tandem mass spectrometry
Authors: Crnogorac Goranka , Schmauder Sabrina , Schwack Wolfgang
Published: July 2008

The simultaneous determination of dithiocarbamate (DTC) fungicide residues on fruits and vegetables was performed by liquid chromatography (LC) on a ZIC‐pHILIC column coupled to tandem mass spectrometry (MS/MS). For each DTC subclass, i.e. dimethyldithiocarbamates (DMDs), ethylenebis(dithiocarbamates) (EBDs), and propylenebis(dithiocarbamates) (PBDs), the limits of detection and quantification were approximately 0.001 and 0.005 mg kg−1, respectively. Recoveries from tomatoes, spiked in the range of 0.05–1 mg kg−1, averaged between 97 and 101%. Several fruits and vegetables from a local market and different countries of origin (apples, pears, grapes, cherry tomatoes, cocktail tomatoes, cucumbers, tomatoes, tamarillos, papaya, and broccoli) were analyzed by LC/MS/MS, LC/MS, and by the routine CS2 method. In general, the results obtained by both LC/MS and LC/MS/MS were in good agreement with those obtained by the CS2 method except for the false positive CS2 results for broccoli and papaya. The results demonstrate that both LC/MS and LC/MS/MS can be used for routine analyses of DTC residues, whereat LC/MS/MS is more sensitive and selective than LC/MS. Copyright © 2008 John Wiley & Sons, Ltd.
A backstepping design for directed formation control of three‐coleader agents in the plane
Authors: Chen Yang‐Yang , Tian Yu‐Ping
Published: July 2008

This paper deals with a directed formation control problem of three agents moving in the plane, where the agents have a cyclic ordering with each one required to maintain a nominated distance from its neighbor, and each agent is described by a double integrator. Firstly, a directed formation control law based on the knowledge only of the neighbor's direction is designed by using the integrator backstepping technique, which can not only accomplish the desired triangle formation but also ensure that speeds of all agents converge to a common value without collision between each other during the motion. Then, with the purpose of relaxing and even overcoming the restriction of initial conditions of the agents owing to collision avoidance, we introduce the inter‐agent potential functions into the design. The convergence of the proposed control algorithms is proved by using tools from LaSalle's invariance principle. Simulation results are provided to illustrate the effectiveness of the control laws. Copyright © 2008 John Wiley & Sons, Ltd.
Robust discrete‐time output feedback model reference control design with state and unknown input estimation
Authors: Chang Jeang‐Lin
Published: July 2008

For MIMO discrete‐time linear systems with unknown input in which the matching condition does not hold, the use of estimation method in an output feedback controller is proposed in this paper. Provided that the variation of unknown input in the two consecutive sampling instances is not changed significantly, both the system state and unknown input can be simultaneously estimated by our proposed observer algorithm with the estimation error being constrained in a small bounded region of the order of O(T). Then, a method utilizing command generator tracker is designed to generate the reference model. Concurrently with the estimations of the system state and unknown input are used in the controller where it can cause the tracking error to be bounded in a small region with the guaranteed system stability. Finally, the feasibility of our algorithm can be proved to be valid through the demonstration of a simulation‐based example. Copyright © 2008 John Wiley & Sons, Ltd.
Test methods to characterise differently designed tribomaterials
Authors: Gruen F. , Godor I. , Eichlseder W.
Published: July 2008

In this study, we present the development of model scale tribological test methods using the model ring‐on‐disc. The methods enable the demonstration of processes that occur in sliding materials during operation and subsequent breakdown. Currently, existing test methods are not able to visualise these complex processes to the same extent. We designed adapted test programmes for the visualisation of different material properties. This paper discusses the suitability and the significance of these test programmes. We benchmarked the test methods on selected metal‐based and plastic tribomaterials (CuPb22Sn2 and Polytetraflaoroethylene (PTFE) and bronze (Bz)) under lubricated and non‐lubricated conditions. We conducted an extensive damage analysis of the surfaces and surface layers. Furthermore, the classification of the damage patterns and the tribometric results are the basis for the development of models that are capable of representing the most important states during operation. The models are of sufficient quality to assist in the further optimisation of the materials. Copyright © 2008 John Wiley & Sons, Ltd.
Spiritual development: A missing priority in youth development
Authors: Benson Peter L. , Roehlkepartain Eugene C.
Published: July 2008

Addressing the spiritual development of young people has the potential to strengthen youth work and its outcomes. Spiritual development matters because it is an intrinsic part of being human and because young people themselves view it as important. This article reviews the research that points to positive impacts of spiritual development for youth and notes that in an increasingly pluralistic society, everyone needs to build skills for negotiating religious and spiritual diversity. The authors propose that spiritual development involves, in part, the dynamic interplay of three dimensions: belonging and connecting, awareness and awakening, and a way of living. Three initial challenges and opportunities are emerging: empowering youth to explore core developmental issues, motivation and focus, and multisector engagement.
Spiritual development in faith communities and secular societies
Authors: Emmett John A.
Published: July 2008

In this article, the author writes lyrically of the struggle of young people to find meaning and hope in an increasingly secular world, and focuses his discussion on potential roles for adults “who are in serious life‐shaping relationships with young people … to recognize and respond to the spiritual development of young people.” The first role he suggests is similar to that of a museum curator: a knowledgeable adult can provide accessibility to the artifacts and practices of various cultures and spiritual traditions, help young people understand their own experience with those artifacts, and offer possible interpretations. The second role is similar to that of a navigator on a journey of exploration.
Contemplative education and youth development
Authors: Jennings Patricia A.
Published: July 2008

Contemplative education includes practices that aim to help a person cultivate conscious awareness, especially internal self‐awareness and awareness of one's connection to the world. Such practices include meditation, movement, and the contemplation of nature. Exploration is under way to determine if these practices might assist young people in their development, as they do in adulthood.
Spiritual development in youth worker preparation: A matter of resolve
Authors: Kimball Elisabeth M.
Published: July 2008

Once we are convinced that attentiveness to spiritual development has the potential to enrich and improve youth work practice, equipping youth workers with the necessary skills and capacities can proceed. A model for such preparation begins with youth workers' reflecting on their own spiritual autobiographies.
Fungible Weights in Multiple Regression
Authors: Waller Niels G.
Published: July 2008

Every set of alternate weights (i.e., nonleast squares weights) in a multiple regression analysis with three or more predictors is associated with an infinite class of weights. All members of a given class can be deemed fungible because they yield identical SSE (sum of squared errors) and R2 values. Equations for generating fungible weights are reviewed and an example is given that illustrates how fungible weights can be profitably used to evaluate parameter sensitivity in multiple regression.
On Association Coefficients for 2×2 Tables and Properties That Do Not Depend on the Marginal Distributions
Authors: Warrens Matthijs J.
Published: July 2008

We discuss properties that association coefficients may have in general, e.g., zero value under statistical independence, and we examine coefficients for 2×2 tables with respect to these properties. Furthermore, we study a family of coefficients that are linear transformations of the observed proportion of agreement given the marginal probabilities. This family includes the phi coefficient and Cohen’s kappa. The main result is that the linear transformations that set the value under independence at zero and the maximum value at unity, transform all coefficients in this family into the same underlying coefficient. This coefficient happens to be Loevinger’s H.
Precocious gut maturation and immune cell expansion by single dose feeding the lectin phytohaemagglutinin to suckling rats
Authors: Prykhod'ko Olena , Fed'kiv Olexandr , Linderoth Ann , Pierzynowski Stefan G. , Weström Björn R.
Published: July 2008

The dietary lectin phytohaemagglutinin (PHA) induces gut growth and precocious maturation in suckling rats after mucosal binding. The present study investigated the dose range in which PHA provokes gut maturation and if it coincided with immune activation. Suckling rats, aged 14 d, were orogastrically fed a single increasing dose of PHA: 0 (control), 2, 10, 50 or 250 μg/g body weight (BW) in saline. The effect on gut, lymphoid organs and appearance of CD3+(T-lymphocyte) and CD19+(B-lymphocyte) cells in the small-intestinal mucosa was studied at 12 h (acute) and 3 d (late phase) after treatment. The low PHA doses (2 and 10 μg/g BW) induced intestinal hyperplasia without mucosal disarrangement but did not provoke gut maturation. Only the high PHA doses (50 and 250 μg/g BW) temporarily disturbed the intestinal mucosa with villi shortening and decrease in disaccharidase activities, and later after 3 d provoked precocious maturation, resulting in an increase in maltase and sucrase activities and decrease in lactase activity and disappearance of the fetal vacuolated enterocytes in the distal small intestine. Exposure to the high, but not to the low, PHA doses increased the number of mucosal CD19+and CD3+cells in the small intestine after 12 h, a finding also observed in untreated weaned rats aged 21–28 d. In conclusion, there was a dose-related effect of PHA on gastrointestinal growth and precocious maturation that coincided with a rapid expansion of mucosal B- and T-lymphocytes, indicating a possible involvement of the immune system in this process.
Question: What Are the Fruitful New Directions in Subaltern Studies, and How Can Those Working in Middle East Studies Most Productively Engage With Them?
Authors: Chalcraft John
Published: July 2008

More than twenty-five years ago, a small group of South Asianists challenged the bourgeois-nationalist and colonialist historiography of Indian nationalism. Based mostly in India and critical of “economistic” Marxism, they aimed to recover the occluded histories of what Antonio Gramsci calls “subaltern social groups” and to put into question the relations of power, subordination, and “inferior rank” more generally. The influence of subaltern studies quickly became international, inspiring research projects in Africa, Asia, the Caribbean, Latin America, and the Middle East.
Phylogeography of the blue land crab,Cardisoma guanhumi(Decapoda: Gecarcinidae) along the Brazilian coast
Authors: De Oliveira-Neto José F. , Pie Marcio R. , Chammas Marcelo A. , Ostrensky Antonio , Boeger Walter A.
Published: July 2008

Several crab species are important fishery resources in Brazil and their overexploitation has lead to severe population declines in some regions. The management of populations of these species should take into account the degree of gene flow among populations in different estuaries. The goal of the present study is to assess the degree of geographical structure in the genetic diversity of the blue land crab,Cardisoma guanhumi, along the Brazilian coast. A fragment of the control region of the mtDNA (750 bp) was sequenced for 95 specimens collected across 5 Brazilian states. Analyses using F-statistics failed to indicate any evidence of geographical structure, a result that was corroborated by a nested clade analysis of the same dataset. Mismatch distribution analyses indicated that populations of the blue land crab have experienced an expansion during their recent evolutionary past. The obtained results are similar to those recently described for another sympatric crab,Ucides cordatus, particularly with respect to the extensive degree of gene flow. However, populations ofC. guanhumiseem to be older than those ofU. cordatusand do not show the north–south expansion found in that species.
On the genera Meximaera, Ruffomaera gen. nov., Maeropsis and Ceradocus from Atlantic coasts (Amphipoda: Melitidae)
Authors: Krapp-Schickel Traudl
Published: July 2008

Melitid amphipods belonging to the Maera–Ceradocus-group are re-examined from the Atlantic coast using material from the collection in the Smithsonian Institution (Washington): Ruffomaera gen. nov. is established for Maera williamsi, furthermore Meximaera briani sp.nov., Maeropsis cf. perrieri and Ceradocus breweri (transferred from Gammarus) are described and illustrated.
Thin shell aerogel fabrication for FIREX-I targets using high viscosity (phloroglucinol carboxylic acid)/formaldehyde solution
Authors: Yang H. , Nagai K. , Nakai M. , Norimatsu T.
Published: July 2008

Capsules with a thin aerogel shell were prepared by the OO/W/OIemulsion process. (Phloroglucinol carboxylic acid)/formaldehyde (PF) was used as the water phase (W) solution to form the shell of the capsule. PF is a linear polymer prepared from phloroglucinol carboxylic acid. The viscosity of the PF solution can reach a high level of 9×10−5m2/s without gelation while resorcinol/formaldehyde (RF) gelates at ~3–4×10−5m2/s. Using the viscous PF solution, capsule with a 17 µm gel shell was fabricated. This thickness satisfies the specification of the first phase of Fast Ignition Realization Experiment (FIREX-I) at Osaka University. When PF gel was extracted to remove the organic solvent, shrinkage of 9% occurred. The final density of the PF aerogel was 145 mg/cm3. Both the shell thickness and density can satisfy the specification of FIREX-I. The pore size of the PF aerogel was less than 100 nm while that of RF was 200–500 nm. The SEM showed that PF had particle-like foam structure while RF had fibrous-like foam structure.
Objective indicators of pasture degradation from spectral mixture analysis of Landsat imagery
Authors: Davidson Eric A. , Asner Gregory P. , Stone Thomas A. , Neill Christopher , Figueiredo Ricardo O.
Published: July 2008

Degradation of cattle pastures is a management concern that influences future land use in Amazonia. However, “degradation” is poorly defined and has different meanings for ranchers, ecologists, and policy makers. Here we analyze pasture degradation using objective scalars of photosynthetic vegetation (PV), nonphotosynthetic vegetation (NPV), and exposed soil (S) derived from Landsat imagery. A general, probabilistic spectral mixture model decomposed satellite spectral reflectance measurements into subpixel estimates of PV, NPV, and S covers at ranches in western and eastern Amazonia. Most pasture management units at all ranches fell along a single line of decreasing PV with increasing NPV and S, which could be considered a degradation continuum. The ranch with the highest stocking densities and most intensive management had greater NPV and S than a less intensively managed ranch. The number of liming, herbiciding, and disking treatments applied to each pasture management unit was positively correlated with NPV and negatively correlated with PV. Although these objective scalars revealed signs of degradation, intensive management kept exposed soil to <40% cover and maintained economically viable cattle production over several decades. In ranches with few management inputs, the high PV cover in young pastures declined with increasing pasture age, while NPV and S increased, even where grazing intensity was low. Both highly productive pastures and vigorous regrowth of native vegetation cause high PV values. Analysis of spectral properties holds promise for identifying areas where grazing intensity has exceeded management inputs, thus increasing coverage of senescent foliage and exposed soil.
Development of a “smart” tracer for the assessment of microbiological activity and sediment‐water interaction in natural waters: The resazurin‐resorufin system
Authors: Haggerty Roy , Argerich Alba , Martí Eugènia
Published: July 2008

A “smart” tracer is a tracer that provides, directly or through measurement of its concentration or in combination with another compound, at least one “bit” more of information about the environment through which it travels than a conservative tracer. In this study we propose and present the chemical compound resazurin as a smart tracer to assess the coupling between solute transport and microbiological activity in sediment‐water interfaces in freshwaters. Resazurin is a weakly fluorescent redox‐sensitive dye that undergoes an irreversible reduction to strongly fluorescent resorufin under mildly reducing conditions, most commonly in the presence of living microorganisms. To investigate the suitability of resazurin as a smart tracer, we characterized the decay, sorption, reaction, and transport behavior of resazurin and resorufin in various waters and sediments using laboratory experiments. Results show that resazurin irreversibly and rapidly reacts to resorufin in colonized sediment with pseudo‐first‐order behavior and a rate coefficient of 1.41 h−1. This reaction is 3 orders of magnitude faster than that in stream water alone, indicating the tracer is sensitive to microbiological activity and associated sediment‐water interactions. The compounds are affected by significant sorption, with an approximately linear isotherm and a Kd of 6.63 mL/g for resorufin in sediment with 2.19% organic carbon. The compounds are stable over weeks in natural water, except in the presence of strong light where significant photochemical decay may occur more rapidly.
Cell Proteomic Footprint
Authors: Lokhov Petr , Balashova Elena , Dashtiev Maxim
Published: July 2008

The authentication of mammalian cell cultures and their subpopulations are of tremendous demand in biotechnology and cell therapy. However, current techniques are either not efficient or can be very complex and expensive. Here we report a simple and straightforward approach for authentication of biological cells and their subpopulations with high speed, high throughput, low sample cost, and high sensitivity. We discovered that cell cultures treated with protease at soft, “non-killing” conditions release fragments of cell surface proteins, which composition is a strong characteristic of the cells. Mass spectrometric analysis of the released fragments allows a direct comparison of the produced mass spectrum with the mass spectrum of known cells. As an example, we applied this technique to verify subpopulations of human fibroblasts which have different origins and exhibit different medical characteristics.
Transcription factories
Authors: Carter David R.F. , Eskiw Christopher , Cook Peter R.
Published: July 2008

There is increasing evidence that different transcription units are transcribed together in discrete nuclear structures known as transcription factories. Various new techniques enable us to detect and characterize these structures. We review the latest findings and discuss how they support a model for transcription and chromosome organization.
Translational control in early development: CPEB, P-bodies and germinal granules
Authors: Standart Nancy , Minshall Nicola
Published: July 2008

Selective protein synthesis in oocytes, eggs and early embryos of many organisms drives several critical aspects of early development, including meiotic maturation and entry into mitosis, establishment of embryonic axes and cell fate determination. mRNA-binding proteins which (usually) recognize 3′-UTR (untranslated region) elements in target mRNAs influence the recruitment of the small ribosomal subunit to the 5′ cap. Probably the best studied such protein is CPEB (cytoplasmic polyadenylation element-binding protein), which represses translation in the oocyte in a cap-dependent manner, and activates translation in the meiotically maturing egg, via cytoplasmic polyadenylation. Co-immunoprecipitation and gel-filtration assays revealed that CPEB in Xenopus oocytes is in a very large RNP (ribonucleoprotein) complex and interacts with other RNA-binding proteins including Xp54 RNA helicase, Pat1, RAP55 (RNA-associated protein 55) and FRGY2 (frog germ cell-specific Y-box protein 2), as well as the eIF4E (eukaryotic initiation factor 4E)-binding protein 4E-T (eIF4E-transporter) and an ovary-specific eIF4E1b, which binds the cap weakly. Functional tests which implicate 4E-T and eIF4E1b in translational repression in oocytes led us to propose a model for the specific inhibition of translation of a target mRNA by a weak cap-binding protein. The components of the CPEB RNP complex are common to P-bodies (processing bodies), neuronal granules and germinal granules, suggesting that a highly conserved ‘masking’ complex operates in early development, neurons and somatic cells.
Regulation of translation initiation by herpesviruses
Authors: Smith Richard W.P. , Graham Sheila V. , Gray Nicola K.
Published: July 2008

Viruses are dependent upon the host cell protein synthesis machinery, thus they have developed a range of strategies to manipulate host translation to favour viral protein synthesis. Consequently, the study of viral translation has been a powerful tool for illuminating many aspects of cellular translational control. Although much work to date has focused on translational regulation by RNA viruses, DNA viruses have also evolved complex mechanisms to regulate protein synthesis. Here we summarize work on a large family of DNA viruses, the Herpesviridae, which have evolved mechanisms to sustain efficient cap-dependent translation and to regulate the translation of specific viral mRNAs.
Translational termination–re-initiation in viral systems
Authors: Powell Michael L. , Brown T. David K. , Brierley Ian
Published: July 2008

Viruses have evolved a number of translational control mechanisms to regulate the levels of expression of viral proteins on polycistronic mRNAs, including programmed ribosomal frameshifting and stop codon readthrough. More recently, another unusual mechanism has been described, that of termination-dependent re-initiation (also known as stop–start). Here, the AUG start codon of a 3′ ORF (open reading frame) is proximal to the termination codon of a uORF (upstream ORF), and expression of the two ORFs is coupled. For example, segment 7 mRNA of influenza B is bicistronic, and the stop codon of the M1 ORF and the start codon of the BM2 ORF overlap in the pentanucleotide UAAUG (stop codon of M1 is shown in boldface and start codon of BM2 is underlined). This short review aims to provide some insights into how this translational coupling process is regulated within different viral systems and to highlight some of the differences in the mechanism of re-initiation on prokaryotic, eukaryotic and viral mRNAs.
Methods for studying global patterns of DNA binding by bacterial transcription factors and RNA polymerase
Authors: Grainger David C. , Busby Stephen J.W.
Published: July 2008

A major goal in the study of gene regulation is to untangle the transcription-regulatory networks of Escherichia coli and other ‘simple’ organisms. To do this we must catalogue the binding sites of all transcription factors. ChIP (chromatin immunoprecipitation), combined with DNA microarray analysis, is a powerful tool that permits global patterns of DNA binding to be measured. Here, we discuss the benefits of this approach and the application of this technique to bacterial systems.
Visualizing the organization and reorganization of transcription complexes for gene expression
Authors: Burrows Patricia C. , Wigneshweraraj Sivaramesh , Bose Dan , Joly Nicolas , Schumacher Jörg , Rappas Mathieu , Pape Tilmann , Stockley Peter G. , Zhang Xiaodong , Buck Martin
Published: July 2008

Regulated gene expression requires control of the transcription machinery, frequently through the establishment of different functional states of the transcribing enzyme RNA polymerase and its attendant activator proteins. In bacteria, major adaptive responses use an enhancer-dependent RNA polymerase, activated for transcription by a class of ATPases that remodel initial promoter complexes to form transcriptionally proficient open promoter complexes. In the present article, we summarize the integrated use of site-specific protein cleavage and DNA cross-linking methods, as well as FRET (fluorescence resonance energy transfer) in combination with X-ray crystallography and cryo-electron microscopy to gain insight into the organization of the enhancer-dependent σ54–RNA polymerase and the ATPase-driven activation mechanism.
African American English: An Overview
Authors: Charity Anne Harper
Published: July 2008

This article presents a summary of African-American English (AAE) for the speech-language pathologist. An overview of research on AAE and of the specific linguistic characteristics of AAE is presented. Examples of lexical, phonological, grammatical, and prosodic features of AAE and their implications for assessment are discussed. Linguistic variation within AAE is also described. Educational issues surrounding AAE and teachers' attitudes concerning student use of AAE are considered. The challenges in assessment that AAE presents for the SLP are highlighted along with resources for further information regarding AAE.
Theory in the Balance
Authors: Kent Ray D.
Published: July 2008

One major way of putting into view the scientific progress in an area of research is by examining the theoretical currents that help to organize the data and to guide future experiments. Research in speech production has been shaped by several different theories, but three in particular have had a profound influence: general motor program theory, dynamic systems theory, and internal models. This paper discusses how these three theories evolved and influenced contemporary conceptions of how speech production is controlled.
Managing Voice and Communication for Tracheostomized and Ventilator Dependent Patients: Clinical Case Studies
Authors: Dikeman Karen J. , Kazandjian Marta S.
Published: July 2008

This tutorial provides a background to the history of tracheostomy and ventilator-dependence, as well as two clinical case studies that describe the management of voice and communication. The rationale for establishment of upper airway flow in the tracheostomized and ventilator-dependent patient is explained. Assessment and treatment paradigms are described for the clinician working with this complex population, in order to provide guidelines for daily clinical practice.
Nonplatelet Effects of Aspirin During Acute Coronary Occlusion: Electrophysiologic and Cation Alterations in Ischemic Myocardium
Authors: Shehadeh Abbas A. , Arena Joseph , Moschos Christos B. , Regan Timothy J.
Published: July 2008

Background: Mortality after acute myocardial ischemia has been reduced by aspirin (ASA) but mechanisms other than the antiplatelet effect have not been established. This article evaluates an antiarrhythmic action during sympathetic stimulation in the intact anesthetized dog with and without ischemia.

Methods and Results: The ventricular fibrillation threshold (VFT) was examined before and after epinephrine (E) in normals (group I). A VFT reduction during E was normalized after 1 week of ASA (P < .01). Regional myocardial ischemia for I hour resulted in similar hypoperfusion in controls of group II and after ASA. Action potential responses in isolated superfused ischemic tissue showed prolonged repolarization (APD90) in response to E, which was normalized after ASA (P < .01). To assess the antiarrhythmic role of the anion in group III, Na salicylate was given. During 1 hour of ischemia, the VF incidence was reduced and cation abnormalities diminished in ischemic myocardium compared with untreated ischemia.

Conclusions: ASA antagonizes the reduction of the VFT induced by catecholamine in nor mals as well as the repolarization abnormality elicited by E during acute ischemia. The salicylate anion appears to be the active component in view of the efficacy in preventing VF during the early ischemic period.
Vitamin K Modulates Cardiac Action Potential by Blocking Sodium and Potassium Ion Channels
Authors: Drolet Benoit , Emond Annie , Pharm B. , Fortin Vincent , Daleau Pascal , Rousseau Guy , Cardinal René , Turgeon Jacques
Published: July 2008

Background: Cardiovascular collapses, syncopes, and sudden deaths have been observed following the rapid administration of intravenous vitamin K. Our objectives were to characterize the effects of vitamin K on cardiac action potentials and to evaluate effects of vitamin K on sodium and potassium currents, namely INa, IKr, and IKs.

Methods and Results: Guinea pig hearts (n = 21) were paced at a cycle length of 250 msec and exposed to vitamin K at 1.15-4.6 μmol/L (2.5-10 mg/L). Monophasic action potential duration measured at 90% repolarization (MAPD90) was not significantly reduced (-1.6 ± 0.3 msec; P > .05; N.S.) at 1.15 μmol/L, but increased by 6.5 ± 0.4 msec ( P < .05) at 2.3 μmol/L. MAPD90was not measurable at 4.6 μmol/L, as a result of inexcitability. Patch-clamp experiments in ventricular myocytes demonstrated a' ~50% reduction in INaby 10 μmol/L vitamin K and a concentration-dependent reduction of the K+current elicited by short depolarizations (250 msec; IK250). Estimated IC50for IK250, mostly representing IKr, was 2.3 μmol/L. Vitamin K was less potent to block the K+current elicited by long depolarizations (5,000 msec; IK5000), mostly representing IKs, with an estimated IC50over 100 μmol/L. Conclusions: Therapeutic concentrations (~1.5 μmol/L) of intravenous vitamin K modulate cardiac action potential by blocking ionic currents involved in cardiac depolarization and repolarization.
IR pyrometry in diamond anvil cell above 400K
Authors: Shuker P. , Melchior A. , Assor Y. , Belker D. , Sterer E.
Published: July 2008

Temperature measurements in a laser heated diamond anvil cell (DAC) are currently limited to temperatures above 1000K using optics and detectors in the visible range. We have built a pyrometer in the IR range and expanded the lower limit of temperature detection to 400K. The pyrometer is designed for very low thermal radiation intensities, measured sequentially through a set of bandpass filters in the range of 1.2–3.4μm using very efficient IR photodetectors. The thermal radiation from the center of the cw Nd:YAG laser heated spot is least square fitted to a Planck curve, using a gray body approximation. Melting is detected by changes in the light scattering picture of an auxiliary He–Ne laser from the surface of the hot spot, and by a change in slope in the plot of hot spot temperature versus laser power. In this work we demonstrate measurement of the melting curve of zinc up to 25GPa. The melting curve is in very good agreement with previous results which were taken up to 6GPa in a large volume press.
Energy-switching potential energy surface for the water molecule revisited: A highly accurate singled-sheeted form
Authors: Galvão B. R. L. , Rodrigues S. P. J. , Varandas A. J. C.
Published: July 2008

A global ab initio potential energy surface is proposed for the water molecule by energy-switching/merging a highly accurate isotope-dependent local potential function reported by Polyansky et al. [Science 299, 539 (2003)] with a global form of the many-body expansion type suitably adapted to account explicitly for the dynamical correlation and parametrized from extensive accurate multireference configuration interaction energies extrapolated to the complete basis set limit. The new function mimics also the complicated Σ∕Π crossing that arises at linear geometries of the water molecule.
Understanding the rate of spin-forbidden thermolysis of HN3 and CH3N3
Authors: Besora Maria , Harvey Jeremy Noel
Published: July 2008

The pyrolysis of the simplest azides HN3 and CH3N3 has been studied computationally. Nitrogen extrusion leads to the production of NH or CH3N. The azides have singlet ground states but the nitrenes CH3N and NH have triplet ground states. The competition between spin-allowed decomposition to the excited state singlet nitrenes and the spin-forbidden N2 loss is explored using accurate electronic structure methods (CASSCF/cc-pVTZ and MR-AQCC/cc-pVTZ) as well as statistical rate theories. Nonadiabatic rate theories are used for the dissociation leading to the triplet nitrenes. For HN3, N3H formation is predicted to dominate at low energy, and the calculated rate constant agrees very well with energy-resolved experimental measurements. Under thermal conditions, however, the singlet and triplet pathways are predicted to occur competitively, with the spin-allowed product increasingly favored at higher temperatures. For CH3N3 thermolysis, spin-allowed dissociation to form C1H3N should largely dominate at all temperatures, with spin-forbidden formation of C3H3N almost negligible. Singlet methyl nitrene is very unstable and should rearrange to CH2NH immediately upon formation, and the latter species may lose H2 competitively with vibrational cooling, depending on temperature and pressure.
Investigating isomerization reactions in solid state by using simultaneous high overtone pumping and Raman detection
Authors: Olbert-Majkut Adriana , Ahokas Jussi , Lundell Jan , Pettersson Mika
Published: July 2008

Formation of the unstable cis-formic acid in solid argon matrix is induced by direct excitation of the 6←0 transition of the ν(OH) vibration of the trans-formic acid. The experiment utilizes strongly focused laser beam that produces relatively high isomerization rate despite the low cross section of the absorption. Raman spectroscopy in a backscattering geometry is used for detection of the reactants and the products. This experimental arrangement allow us to use the same laser source for simultaneous pumping and Raman excitation, and it also guarantees that the excited and probed volumes overlap. The presented method has a high potential for solid state investigations of chemical reactions on the ground electronic state.
Intermediate phases in rhombohedral Pb(Mg1∕3Nb2∕3)1−xTixO3 crystal
Authors: Tu C.-S. , Chuang H.-T. , Lee S.-C. , Chien R. R. , Schmidt V. H. , Luo H.
Published: July 2008

Phase transformations of (111)-cut Pb(Mg1∕3Nb2∕3)1−xTixO3 (x=0.30) single crystals before and after an electric (E)–field poling have been investigated by means of dielectric permittivity, hysteresis loop, polarization current, and in situ x-ray diffraction as a function of temperature. An R-T-C transition sequence was observed in the unpoled sample upon zero-field heating. R, T, and C are rhombohedral, tetragonal, and cubic phases, respectively. After a prior E-field poling, an extra intermediate monoclinic (possible MA) phase was induced and the crystal underwent an R-MA-T-C phase sequence with significant responses in polarization current. The dielectric dispersion was diminished after poling and reappeared in the cubic state. The dielectric permittivities with and without a prior poling were found to follow the Curie–Weiss equation, ε′=C∕(T−T0), above the Burns temperature 505K with the same constants C=1.9×105 K and T0=460K.
Distribution and segregation of arsenic at theSiO2/Si interface
Authors: Steen C. , Martinez-Limia A. , Pichler P. , Ryssel H. , Paul S. , Lerch W. , Pei L. , Duscher G. , Severac F. , Cristiano F. , Windl W.
Published: July 2008

The segregation and pile-up of arsenic atoms at the Si/SiO2 interface in steady state was investigated in detail by a combination of gracing incidence x-ray fluorescence spectroscopy (GI-XRF) measurements, electrical measurements, etching on the nanometer scale, and measurements of the step heights by interferometry. Using GI-XRF measurements and removal of the highly doped segregation layer by a sensitive etching process it was possible to distinguish clearly between the piled-up atoms and the arsenic atoms in the bulk over a large range of implantation doses, from 3×1012 to 1×1016 cm−2. The samples were annealed at different temperatures from 900 °C to 1200 °C for time periods long enough to make sure that the segregation reflects an equilibrium state. With additional step height measurements at line-space structures, the thickness of the layer with the piled-up arsenic and the shape of the segregation profile was determined. Electrical measurements indicated that the segregated arsenic atoms are deep donors with an electrical activity that increases eventually to full electrical activation for high sheet concentrations of the segregated atoms. The measured data can be modeled as a steady state of neutral arsenic atoms in the segregation layer with positively charged substitutional arsenic atoms and free electrons. For the highest concentration, a saturation of the sheet concentration of segregated arsenic atoms was observed that correlates with the increase in electrical activation. For the use in process simulation programs, a three-phase segregation model was adapted and calibrated.