bluuebunny/crossref_metadata_2025 huggingface dataset:
Understanding short‐ and long‐term implications of “myopic” fleet maintenance policies: a system dynamics application to a city bus company
Authors: Bivona Enzo , Montemaggiore Giovan Battista
Published: September 2010

Financial losses recorded in city bus companies often force managers to implement restructuring strategies aimed at improving business results. However, such decisions may not produce the expected consequences for a number of reasons. Both the internal and external environment in which such companies operate can make the design and implementation of long‐term sustainable policies quite difficult. In fact, the result may be that decision makers introduce “effective” policies in a company subsystem, while ignoring the medium‐ and long‐term implications of such decisions in the performance of the whole company. With the aim to detect the main causes underlying “myopic” fleet maintenance policies, an empirical analysis of two major Italian city bus companies has been conducted. This approach allowed the authors to make explicit the network of cause‐and‐effect relationships between different business subsystems and to build a system dynamics model to support city bus managers in designing and assessing alternative long‐term sustainable strategies. Copyright © 2010 John Wiley & Sons, Ltd.
Exonucleases and endonucleases involved in polyadenylation‐ assisted RNA decay
Authors: Slomovic Shimyn , Schuster Gadi
Published: September 2010

RNA polyadenylation occurs in most forms of life, excluding a small number of biological systems. This posttranscriptional modification undertakes two roles, both of which influence the stability of the polyadenylated transcript. One is associated with the mature 3′ ends of nucleus‐encoded mRNAs in eukaryotic cells and is important for nuclear exit, translatability, and longevity. The second form of RNA polyadenylation assumes an almost opposite role; it is termed ‘transient’ and serves to mediate the degradation of RNA. Poly(A)‐assisted RNA decay pathways were once thought to occur only in prokaryotes/organelles but are now known to be a common phenomenon, present in bacteria, organelles, archaea, and the nucleus and cytoplasm of eukaryotic cells, regardless of the fact that in some of these systems, stable polyadenylation exists as well. This article will summarize the current knowledge of polyadenylation and degradation factors involved in poly(A)‐assisted RNA decay in the domains of life, focusing mainly on that which occurs in prokaryotes and organelles. In addition, it will offer an evolutionary view of the development of RNA polyadenylation and degradation and the cellular machinery that is involved. WIREs RNA 2011 2 106–123 DOI: 10.1002/wrna.45

This article is categorized under:

RNA Turnover and Surveillance > Turnover/Surveillance Mechanisms

RNA Turnover and Surveillance > Regulation of RNA Stability
Angeregte Zustände von Chrom (III)‐Komplexionen und ihre Bedeutung für Photochemie und Lumineszenz
Authors: Schläfer Hans Ludwig
Published: September 2010

Professor Dr. Hans Ludwig Schläfer, Persönlicher Ordinarius für physikalische Chemie an der Johann‐Wolfgang‐Goethe‐Universität Frankfurt am Main, verstarb am 22 August 1969. Das im folgenden veröffentlichte Manuskript war von ihm für einen Plenarvortrag auf dem Symposium Koordinationschemie der Übergangselemente, das in Jena vom 22. 25. 9. 1969 stattfand, vollständig ausgearbeitet worden.
Changes in skeletal muscle qualities during enzyme replacement therapy in late‐onset type II glycogenosis: temporal and spatial pattern of mass vs. strength response
Authors: Ravaglia Sabrina , Pichiecchio Anna , Ponzio Michela , Danesino Cesare , Saeidi Garaghani Kolsoum , Poloni Guy Umberto , Toscano Antonio , Moglia Arrigo , Carlucci Annalisa , Bini Paola , Ceroni Mauro , Bastianello Stefano
Published: September 2010

Muscle quality is defined as muscle strength generated per unit muscle mass. If enzyme replacement therapy (ERT) has some effects on type II glycogenosis (GSDII) skeletal muscle pathology, we should be able to measure a change in strength and mass. We conducted a prospective study including 11 patients aged 54.2 ± 11.2 years, referring to a single institution and receiving ERT for ≥2 years. Median Walton score was 3 (2.5–6). Lower limb skeletal muscles were assessed by dynamometry and quantitative muscle MRI. Three segments (anterior thigh, posterior thigh, leg) were analysed separately. Clinical‐MRI correlations were searched for at T0, T6/T8, and T18/24. Changes in lean and fat body composition were assessed by bioelectrical impedance analysis. We found that the anterior thigh showed the best therapeutic response, with an improvement in muscle quality (muscle mass: +7.5%, p = 0.035; strength: +45%, p = 0.002). BMI and lean body mass increased (p = 0.007). Patients with low BMI showed a better outcome. Intramuscular fat accumulation significantly progressed in spite of ERT (+3.7%, p = 0.001), especially in the poorly responsive posterior thigh muscles. Both clinical assessment and MRI revealed a definite improvement in the anterior thigh muscles. However, progression of intramuscular fat accumulation during ERT, as well as the limited responsiveness of posterior thigh muscles, suggests the necessity for early treatment intervention. The better outcome of patients with low BMI, if confirmed, may indicate that dietary protocols could be adopted as adjuvant measures to ERT in adult GSDII.
Training the Millennial Learner Through Experiential Evolutionary Scaffolding: Implications for Clinical Supervision in Graduate Education Programs
Authors: Venne Vickie L. , Coleman Darrell
Published: September 2010

They are the Millennials – Generation Y. Over the next few decades, they will be entering genetic counseling graduate training programs and the workforce. As a group, they are unlike previous youth generations in many ways, including the way they learn. Therefore, genetic counselors who teach and supervise need to understand the Millennials and explore new ways of teaching to ensure that the next cohort of genetic counselors has both skills and knowledge to represent our profession well. This paper will summarize the distinguishing traits of the Millennial generation as well as authentic learning and evolutionary scaffolding theories of learning that can enhance teaching and supervision. We will then use specific aspects of case preparation during clinical rotations to demonstrate how incorporating authentic learning theory into evolutionary scaffolding results in experiential evolutionary scaffolding, a method that potentially offers a more effective approach when teaching Millennials. We conclude with suggestions for future research.
Characterizing the Saltol Quantitative Trait Locus for Salinity Tolerance in Rice
Authors: Thomson Michael J. , de Ocampo Marjorie , Egdane James , Rahman M. Akhlasur , Sajise Andres Godwin , Adorada Dante L. , Tumimbang-Raiz Ellen , Blumwald Eduardo , Seraj Zeba I. , Singh Rakesh K. , Gregorio Glenn B. , Ismail Abdelbagi M.
Published: September 2010

This study characterized Pokkali-derived quantitative trait loci (QTLs) for seedling stage salinity tolerance in preparation for use in marker-assisted breeding. An analysis of 100 SSR markers on 140 IR29/Pokkali recombinant inbred lines (RILs) confirmed the location of the Saltol QTL on chromosome 1 and identified additional QTLs associated with tolerance. Analysis of a series of backcross lines and near-isogenic lines (NILs) developed to better characterize the effect of the Saltol locus revealed that Saltol mainly acted to control shoot Na+/K+ homeostasis. Multiple QTLs were required to acquire a high level of tolerance. Unexpectedly, multiple Pokkali alleles at Saltol were detected within the RIL population and between backcross lines, and representative lines were compared with seven Pokkali accessions to better characterize this allelic variation. Thus, while the Saltol locus presents a complex scenario, it provides an opportunity for marker-assisted backcrossing to improve salt tolerance of popular varieties followed by targeting multiple loci through QTL pyramiding for areas with higher salt stress.
Localizing subcategories in the Bootstrap category of separable C*-algebras
Authors: Dell'Ambrogio Ivo
Published: September 2010

Using the classical universal coefficient theorem of Rosenberg-Schochet, we prove a simple classification of all localizing subcategories of the Bootstrap category Boot ⊂ KK of separable complex C*-algebras. Namely, they are in a bijective correspondence with subsets of the Zariski spectrum Specℤ of the integers – precisely as for the localizing subcategories of the derived category D(ℤ) of complexes of abelian groups. We provide corollaries of this fact and put it in context with the similar classifications available in the literature.
The Risk that Humans Will Soon Be Extinct
Authors: Leslie John
Published: September 2010

If it survives for a little longer, the human race will probably start to spread across its galaxy. Germ warfare, though, or environmental collapse or many another factor might shortly drive humans to extinction. Are they likely to avoid it? Well, suppose they spread across the galaxy. Of all humans who would ever have been born, maybe only one in a hundred thousand would have lived as early as you. If, in contrast, humans soon became extinct then because of the population explosion you would have been ‘fairly ordinary’. Roughly ten per cent of all humans would have been your contemporaries. Now (as the cosmologist Brandon Carter saw to his dismay) a scientific principle tells us not to treat observations as highly extraordinary when they could easily be fairly ordinary. How to apply the principle is controversial, yet it seems we can safely conclude that humanity's chances of galactic colonization cannot be high. Still, we should work to make them as high as possible, resisting those philosophers who argue that human extinction would be no tragedy.
Neo-Positivist or Neo-Kantian? Karl Popper and the Vienna Circle
Authors: Naraniecki Alexander
Published: September 2010

This paper re-contextualises Popper within a Kantian tradition by examining his interaction with the Vienna Circle. The complexity of Popper's relationship to the Vienna Circle is often a point of confusion as some view him as a member of the Vienna Circle while others minimise his association with this group. This paper argues that Popper was not a member of the Vienna Circle or a positivist but shared many neo-Kantian philosophical tendencies with the members of the Circle as well as many of their philosophical problems and interests. By better understanding the influence of the Circle's members upon Popper, we not only remove the myths surrounding Popper's positivism, but also place the logical positivism of the Vienna Circle within its proper philosophical context. This paper further argues that it was Popper's friend during his formative philosophical years in Vienna, Julius Kraft (1921–1960) who was responsible for the way in which Popper approached Kant. Through Kraft, Popper was introduced to the thought of Leonard Nelson (1882–1927) and Jakob Fries (1773–1843) as well as a tradition of critical rationalism which Popper would continue both in his methodological orientation as well as through his late German Enlightenment intellectual values.
Impact of foods with health logo on saturated fat, sodium and sugar intake of young Dutch adults
Authors: Temme Elisabeth HM , van der Voet Hilko , Roodenburg Annet JC , Bulder Astrid , van Donkersgoed Gerda , van Klaveren Jacob
Published: September 2010

Objective

Health logos are introduced to distinguish foods with ‘healthier’ nutrient composition from regular foods. In the present study, we evaluated the effects of changed food compositions according to health logo criteria on the intake of saturated fat, sugar and sodium in a Dutch population of young adults.

Design

Foods in the Dutch food composition table were evaluated against nutrient criteria for logo eligibility. Three replacement scenarios were compared with the nutrient intake ‘as measured’ in the Dutch consumption survey. The foods not complying with health logo criteria were replaced either by ‘virtual’ foods exactly complying with the health logo criteria, with real 2007 market shares (scenario I) and 100 % market shares (scenario II), or by existing similar foods with a composition that already complied with the health logo criteria (scenario III).

Results

The percentage reduction in nutrient intake with the current 2007 market shares of ‘health logo foods’ was −2·5 % for SFA, 0 % for sodium and −1 % for sugar. With a 100 % market share these reductions would be −10 % for SFA, −4 % for sodium and −6 % for sugar. This may lead to a reduction of −40 % for SFA, −23 % for sodium and −36 % for sugar in the most optimal replacement scenario.

Conclusions

With ‘health logo foods’, available in 2007 and current consumption patterns, small reductions can be achieved for SFA and sugar. For additional reductions, lowering the fat/sodium content of meat (products) towards health logo criteria and drinks without sugar towards limits far below health logo criteria would be the most effective reformulation strategy.
Double burden of nutritional disorders in young Iranian children: findings of a nationwide screening survey
Authors: Motlagh Mohammad E , Kelishadi Roya , Amirkhani Mohammad A , Ziaoddini Hasan , Dashti Marziyeh , Aminaee Tahereh , Ardalan Gelayol , Mirmoghtadaee Parisa , Keshavarz Sousan , Poursafa Parinaz
Published: September 2010

Objective

To assess the national prevalence of short stature, underweight, overweight and obesity in 6-year-old Iranian children before school entry.

Design

Cross-sectional nationwide survey.

Setting

Mandatory national screening programme before entrance to elementary school in 2008 in Iran.

Subjects

All Iranian children entering public and private elementary schools.

Results

The study population comprised 862 433 children (48·4 % girls, 77·2 % urban resident). Overall, 6·5 % of children had short stature, 19·1 % were underweight, 12·8 % were overweight and 3·4 % were obese. There was no significant difference in terms of gender, but considerably larger differences were documented among various provinces.

Conclusions

The double burden of nutritional disorders among young children warrants a multi-faceted national policy with evidence-based local programmes. Such planning needs a comprehensive surveillance system and centralized data registry for children’s growth.
A computer model of broad beam transmission through lead material for γ rays and X-rays of different energies
Authors: Al-lehyani Saud H.
Published: September 2010

In radiotherapy, the radiation beam is sometimes shaped so as to deliver different doses to different organs or give a homogeneous dose to structures of different densities. This objective is achieved by the use of attenuating materials introduced into the radiation beam. These attenuators alter the primary as well as the scattered radiation components of the beam and there is at present no accurate method of dose calculation for these situations. Most calculations are performed considering only the effect of the attenuators on the primary radiation beam and can produce large errors in dosimetry. In this study, the broad-beam attenuation is investigated in homogeneous phantoms for various radiation field sizes, photon beam energies and depths in phantom. A mathematical method taking account of primary as well as first scattered radiation is developed. This method predicts reasonably well the transmission through lead attenuators for various experimental conditions.
Rapid palliative radiotherapy: comparing IG-IMRT with more conventional approaches
Authors: Samant Rajiv , Gerig Lee , Montgomery Lynn , MacPherson Miller , Fox Greg , MacRae Robert , Carty Kathy , Andrusyk Steve , Genest Paul , Nyiri Balazs
Published: September 2010

Purpose: To assess the efficiency of an integrated imaging, planning, and treatment delivery system to provide image-guided intensity-modulated radiotherapy (IG-IMRT) for patients requiring palliative radiotherapy (PRT).

Methods: Between December 2006 and May 2008, 28 patients requiring urgent PRT were selected to undergo single-session megavoltage computed tomography (MV-CT) simulation, IMRT treatment planning, position verification and delivery of the first faction of radiotherapy on a helical Tomotherapy® unit. The time required to complete each step was recorded and compared to our standard approach of using either fluoroscopic or CT-based simulation, simplified treatment planning and delivery on a megavoltage unit.

Results: Twenty-eight patients were treated with our integrated IG-IMRT protocol. The median age was 72 years, with 61% men and 39% women. The indications for PRT were: painful bone and soft tissue metastasis (75%); bleeding lesions (14%); and other reasons (11%). The areas treated included the following: hip and/or pelvis (42%); spine (36%); and other areas (21%). The most commonly used dose prescription was 20 Gy in five fractions. Average times for the integrated IG-IMRT processes were as follows: image acquisition, 15 minutes; target delineation, 16 minutes; IMRT treatment planning, 9 minutes; treatment position verification, 10 minutes; and treatment delivery, 12 minutes. The average total time was 62 minutes compared to 66 minutes and 81 minutes for fluoroscopic and CT-simulation-based approaches, respectively. The IMRT dose distributions were also superior to simpler plans.

Conclusions: PRT with an integrated IG-IMRT approach is efficient and convenient for patients, and has potential for future applications such as single-fraction radiotherapy.
The endless race betweenTrypanosoma cruziand host immunity: lessons for and beyond Chagas disease
Authors: Junqueira Caroline , Caetano Braulia , Bartholomeu Daniella C. , Melo Mariane B. , Ropert Catherine , Rodrigues Maurício M. , Gazzinelli Ricardo T.
Published: September 2010

Infection with the protozoan parasiteTrypanosoma cruzi, the agent of Chagas disease, is characterised by a variable clinical course – from symptomless cases to severe chronic disease with cardiac and/or gastrointestinal involvement. The variability in disease outcome has been attributed to host responses as well as parasite heterogeneity. In this article, we review studies indicating the importance of immune responses as key determinants of host resistance toT. cruziinfection and the pathogenesis of Chagas disease. Particular attention is given to recent studies defining the role of cognate innate immune receptors and immunodominant CD8+T cells that recognise parasite components – both crucial for host–parasite interaction and disease outcome. In light of these studies we speculate about parasite strategies that induce a strong and long-lasting T-cell-mediated immunity but at the same time allow persistence of the parasite in the vertebrate host. We also discuss what we have learned from these studies for increasing our understanding of Chagas pathogenesis and for the design of new strategies to prevent the development of Chagas disease. Finally, we highlight recent studies employing a genetically engineered attenuatedT. cruzistrain as a vaccine shuttle that elicits potent T cell responses specific to a tumour antigen and protective immunity against a syngeneic melanoma cell line.
Concluding the WTO services negotiations on domestic regulation – hopes and fears
Authors: DELIMATSIS PANAGIOTIS
Published: September 2010

The negotiations under the aegis of the World Trade Organization (WTO) on the creation of rules on domestic regulations affecting trade in services have entered a critical stage. Within a general atmosphere of reflection and reluctance characterizing the Doha negotiations, this is the only front in recent years in which tangible progress is evident. This paper critically analyses the potential rules that Members currently appear to support and attempts to identify their shortcomings as well as those modifications or clarifications which are necessary to improve the impact and efficacy of the forthcoming rules (so-called ‘disciplines on domestic regulation’ in the parlance used in the General Agreement on Trade in Services – GATS). At the heart of the paper lies a thought-provoking proposal for a necessity test applicable across services sectors. Arguably, only a necessity test can allow for the elimination of unnecessary barriers to trade in services and regulatory arbitrariness.
Tagebuchstudie zu Trinkmotiven, Affektivität und Alkoholkonsum bei Jugendlichen
Authors: Wurdak Mara , Dörfler Tobias , Eberhard Martin , Wolstein Jörg
Published: September 2010

Fragestellung: Aus welchen Motiven trinken Jugendliche Alkohol? Wie hängen Affektivität, Trinkmotive und Alkoholkonsum zusammen? Gibt es jeweils Unterschiede zwischen hoch- und niedrigriskant konsumierenden Jugendlichen? Variieren die Motivstärken tagesabhängig? Methodik: Während eines vierwöchigen Untersuchungszeitraumes wurden bei 38 Jugendlichen zwischen 16 und 17 Jahren Trinkmotive, Affektivität und Alkoholkonsum mithilfe täglicher Fragebogeneinträge erhoben. Neben der statistischen Analyse der gesamten Stichprobe wurden zusätzlich die Angaben von hoch- und niedrigriskant konsumierenden Jugendlichen verglichen. Ergebnisse: Jugendliche trinken vor allem aus Verstärkungs- und sozialen Motiven. Es lassen sich signifikante Korrelationen zwischen Affekt und Trinkmotiven und zwischen Trinkmotiven und Konsummenge feststellen. Hochriskant konsumierende Jugendliche unterscheiden sich von Niedrigrisikotrinkern hinsichtlich ihrer Trinkmotive sowie deren Zusammenhänge mit Affekt und Konsummenge. Die Motivstärken bleiben nicht über alle Trinkereignisse hinweg stabil. Schlussfolgerungen: Präventionsmaßnahmen sollten die unterschiedlichen Motive von Hoch- und Niedrigrisikokonsumenten und deren Beeinflussung durch Affekte berücksichtigen.
Helpline Glücksspielsucht der Medizinischen Universität Wien
Authors: Zanki Malgorzata , Fischer Gabriele
Published: September 2010

Anliegen: Im Rahmen des Projektes Helpline «Spielsucht» bietet die Suchtforschung und Suchttherapie der Medizinischen Universität Wien (MUW) eine Telefonberatung für Personen mit problematischem und pathologischem Spielen und deren Angehörigen an. Die Helpline stellt ein Hilfeangebot dar, das österreichweit schnell, unkompliziert und, wenn es gewünscht wird, auch anonym zu erreichen ist. Ergebnisse: In den ersten 25 Monaten der Projektlaufzeit (Nov. 2006–Dez. 2008) wurden 394 telefonische Erstkontakte registriert, davon waren 86 Anrufer (22 %) Angehörige. Zur diagnostischen Abklärung kamen auf eigenen Wunsch 91 Personen. Fünfundzwanzig Personen waren spezifizierbar als «unterschwellig» (problematisches Spielen); unter 66 pathologischen Spielern (ICD 10: F 63.0; DSM IV: 312.30) waren 38 Personen (57.6 %) mit komorbiden psychischen Störungen (Depression, bipolare affektive Störung, Angststörung, Substanzabhängigkeiten, Schizophrenie, Persönlichkeitsstörungen). Schlussfolgerungen: Helpline «Glücksspielsucht» erfüllt eine wichtige Rolle in der Beratung und Behandlung von Personen mit problematischem und pathologischem Spielverhalten. Die Berücksichtigung der Komorbidität bei der Diagnosestellung und Therapie scheint eine Voraussetzung für den Behandlungserfolg zu sein. Erste Erfahrungen und Ergebnisse lassen eine Verlängerung der Dauer des Projektes sinnvoll und wünschenswert erscheinen.
Schwangerschaft und Alkohol
Authors: Daniel Regine , Novak Astrid , Radler Dunja
Published: September 2010

Hintergrund: Die Konsequenzen pränataler Alkoholexposition sind seit über 30 Jahren in der Literatur umfassend dokumentiert und betreffen neben Geburtskomplikationen vor allem die dauerhafte Schädigung des zentralen Nervensystems. Methodik: Es wurde Literatur der letzten 5 Jahre zum Thema Konsequenzen pränataler Alkoholexposition über die Datenbank «pubmed.gov» und «google.at» recherchiert. Ergebnisse: In westlichen Ländern zählt pränatale Alkoholexposition zu den führenden Ursachen für mentale Entwicklungsverzögerungen. Die Prävalenz der Frauen mit Alkoholerkrankung steigt, doch nicht nur intensiver Alkoholkonsum, sondern auch geringer Gebrauch oder vereinzelte Trinkexzesse werden als riskant eingestuft. Diskussion: Zur Erreichung von Abstinenz/Reduktion des Alkoholkonsums werden neben pharmakologischen vor allem psychosoziale Interventionen propagiert. Wesentlich für langfristige Behandlungserfolge ist die Weiterbetreuung von Hochrisiko-Müttern nach Geburt ihres Kindes, mit Fokus auf Festigung der Mutter-Kind-Beziehung, individuelle Förderung des Kindes sowie Anleitung der Mutter zur Verbesserung von Basisfertigkeiten des alltäglichen Lebens.
Hysteresis of soil moisture spatial heterogeneity and the “homogenizing” effect of vegetation
Authors: Ivanov Valeriy Y. , Fatichi Simone , Jenerette G. Darrel , Espeleta Javier F. , Troch Peter A. , Huxman Travis E.
Published: September 2010

By partitioning mass and energy fluxes, soil moisture exerts a fundamental control on basin hydrological response. Using the design characteristics of the Biosphere 2 hillslope experiment, this study investigates aspects of soil moisture spatial and temporal variability in a zero‐order catchment of a semiarid climate. The hydrological response of the domain exhibits a particular structure, which depends on whether topography‐induced subsurface stormflow is triggered. The occurrence of the latter is conditioned by topography, soil depth, and pre‐storm spatial distribution of moisture. As a result, a non‐unique behavior of soil moisture spatial heterogeneity emerges, manifested through a hysteretic dependence of variability metrics on mean water content. Further, it is argued that vegetation dynamics impose a “homogenizing” effect on pre‐storm moisture states, decreasing the likelihood that a rainfall event will result in topographic redistribution of soil water. Consequently, post‐rainfall soil moisture dynamics associated with the effect of topography that could lead to the enhancement of spatial heterogeneity are suppressed; a potential “attractor” of catchment states emerges. The study thus proposes several hypotheses that will be testable within the framework of long‐term hillslope experiments.
Goals for Near‐Earth‐Object Exploration Examined
Authors: Showstack Randy
Published: September 2010

With Japan's Hayabusa space probe having returned a sample of the Itokawa asteroid this past June, and with NASA's Deep Impact spacecraft impactor having successfully struck comet Tempel 1 in 2006, among other recent missions, the study of near‐Earth objects (NEOs) recently has taken some major steps forward. The recent discovery of two asteroids that passed within the Moon's distance of Earth on 8 September is a reminder of the need to further understand NEOs. During NASA's Exploration of Near‐Earth Objects (NEO) Objectives Workshop, held in August in Washington, D.C., scientists examined rationales and goals for studying NEOs.

Several recent documents have recognized NEO research as important as a scientific precursor for a potential mission to Mars, to learn more about the origins of the solar system, for planetary defense, and for resource exploitation. The October 2009 Review of Human Space Flight Plans Committee report (known as the Augustine report), for example, recommended a “flexible path” for human exploration, with people visiting sites in the solar system, including NEOs. The White House's National Space Policy, released in June, indicates that by 2025, there should be “crewed missions beyond the moon, including sending humans to an asteroid.” In addition, NASA's proposed budget for fiscal year 2011 calls for the agency to send robotic precursor missions to nearby asteroids and elsewhere and to increase funding for identifying and cataloging NEOs.
Daytime tropical D region parameters from short path VLF phase and amplitude
Authors: Thomson Neil R.
Published: September 2010

Observed phases and amplitudes of VLF radio signals, propagating on a short (∼300‐km) path, are used to find improved parameters for the lowest edge of the (D region of the) Earth's ionosphere. The phases, relative to GPS 1‐s pulses, and the amplitudes were measured both near (∼100 km from) the transmitter, where the direct ground wave is very dominant, and at distances of ∼300 km near where the ionospherically reflected waves form a (modal) minimum with the (direct) ground wave. The signals came from the 19.8 kHz, 1 MW transmitter, NWC, on the North West Cape of Australia, propagating ∼300 km ENE, mainly over the sea, to the vicinity of Karratha/Dampier on the N.W. coast of Australia. The bottom edge of the mid‐day tropical/equatorial ionosphere was thus found to be well‐modeled by H′ = 70.5 ± 0.5 km and β = 0.47 ± 0.03 km−1 where H′ and β are the traditional height and sharpness parameters as used by Wait and by the U.S. Navy in their Earth‐ionosphere VLF radio waveguide programs. U.S. Navy modal waveguide code calculations are also compared with those from the wave hop code of Berry and Herman (1971). At least for the vertical electric fields on the path studied here, the resulting phase and amplitude differences (between the ∼100‐km and ∼300‐km sites) agree very well after just a small adjustment of ∼0.2 km in H′ between the two codes. Such short paths also allow more localization than the usual long paths; here this localization is to low latitudes.
GPS measurements of crustal uplift near Jakobshavn Isbræ due to glacial ice mass loss
Authors: Khan Shfaqat Abbas , Liu Lin , Wahr John , Howat Ian , Joughin Ian , van Dam Tonie , Fleming Kevin
Published: September 2010

We analyze 2006–2009 data from four continuous Global Positioning System (GPS) receivers located between 5 and 150 km from the glacier Jakobshavn Isbræ, West Greenland. The GPS stations were established on bedrock to determine the vertical crustal motion due to the unloading of ice from Jakobshavn Isbræ. All stations experienced uplift, but the uplift rate at Kangia North, only 5 km from the glacier front, was about 10 mm yr−1 larger than the rate at Ilulissat, located only ∼45 km further away. This suggests that most of the uplift is due to the unloading of the Earth's surface as Jakobshavn thins and loses mass. Our estimate of Jakobshavn's contribution to uplift rates at Kangia North and Ilulissat are 14.6 ± 1.7 mm yr−1 and 4.9 ± 1.1 mm yr−1, respectively. The observed rates are consistent with a glacier thinning model based on repeat altimeter surveys from NASA's Airborne Topographic Mapper (ATM), which shows that Jakobshavn lost mass at an average rate of 22 ± 2 km3 yr−1 between 2006 and 2009. At Kangia North and Ilulissat, the predicted uplift rates computed using thinning estimates from the ATM laser altimetry are 12.1 ± 0.9 mm yr−1 and 3.2 ± 0.3 mm yr−1, respectively. The observed rates are slightly larger than the predicted rates. The fact that the GPS uplift rates are much larger closer to Jakobshavn than further away, and are consistent with rates inferred using the ATM‐based glacier thinning model, shows that GPS measurements of crustal motion are a potentially useful method for assessing ice‐mass change models.
Limitations of Collateral Flow after Occlusion of a Single Cortical Penetrating Arteriole
Authors: Nishimura Nozomi , Rosidi Nathanael L , Iadecola Costantino , Schaffer Chris B
Published: September 2010

Occlusions of penetrating arterioles, which plunge into cortex and feed capillary beds, cause severe decreases in blood flow and are potential causes of ischemic microlesions. However, surrounding arterioles and capillary beds remain flowing and might provide collateral flow around the occlusion. We used femtosecond laser ablation to trigger clotting in single penetrating arterioles in rat cortex and two-photon microscopy to measure changes in microvessel diameter and red blood cell speed after the clot. We found that after occlusion of a single penetrating arteriole, nearby penetrating and surface arterioles did not dilate, suggesting that alternate blood flow routes are not actively recruited. In contrast, capillaries showed two types of reactions. Capillaries directly downstream from the occluded arteriole dilated after the clot, but other capillaries in the same vicinity did not dilate. This heterogeneity in capillary response suggests that signals for vasodilation are vascular rather than parenchymal in origin. Although both neighboring arterioles and capillaries dilated in response to topically applied acetylcholine after the occlusion, the flow in the territory of the occluded arteriole did not improve. Collateral flow from neighboring penetrating arterioles is neither actively recruited nor effective in improving blood flow after the occlusion of a single penetrating arteriole.
Determination of the Brain–Blood Partition Coefficient for Water in Mice Using MRI
Authors: Leithner Christoph , Müller Susanne , Füchtemeier Martina , Lindauer Ute , Dirnagl Ulrich , Royl Georg
Published: September 2010

Cerebral blood flow (CBF) quantification is a valuable tool in stroke research. Mice are of special interest because of the potential of genetic engineering. Magnetic resonance imaging (MRI) provides repetitive, noninvasive CBF quantification. Many MRI techniques require the knowledge of the brain–blood partition coefficient ( BBPC) for water. Adopting an MRI protocol described by Roberts et al (1996) in humans, we determined the BBPC for water in 129S6/SvEv mice from proton density measurements of brain and blood, calibrated with deuterium oxide/water phantoms. The average BBPC for water was 0.89±0.03 mL/g, with little regional variation within the mouse brain.
A Dynamic in vitro BBB Model for the Study of Immune Cell Trafficking into the Central Nervous System
Authors: Cucullo Luca , Marchi Nicola , Hossain Mohammed , Janigro Damir
Published: September 2010

Although there is significant evidence correlating overreacting or perhaps misguided immune cells and the blood–brain barrier (BBB) with the pathogenesis of neuroinflammatory diseases, the mechanisms by which they enter the brain are largely unknown. For this purpose, we revised our humanized dynamic in vitro BBB model (DIV-BBBr) to incorporate modified hollow fibers that now feature transmural microholes (2 to 4 μm Ø) allowing for the transendothelial trafficking of immune cells. As with the original model, this new DIV-BBBr reproduces most of the physiological characteristics of the BBB in vivo. Measurements of transendothelial electrical resistance (TEER), sucrose permeability, and BBB integrity during reversible osmotic disruption with mannitol (1.6 mol/L) showed that the microholes do not hamper the formation of a tight functional barrier. The in vivo rank permeability order of sucrose, phenytoin, and diazepam was successfully reproduced in vitro. Flow cessation followed by reperfusion (Fc/Rp) in the presence of circulating monocytes caused a biphasic BBB opening paralleled by a significant increase of proinflammatory cytokines and activated matrix metalloproteinases. We also observed abluminal extravasation of monocytes but only when the BBB was breached. In conclusion, the DIV-BBBr represents the most realistic in vitro system to study the immune cell trafficking across the BBB.
A comparison of primary oesophageal squamous epithelial cells with HET‐1A in organotypic culture
Authors: Underwood Timothy J. , Derouet Mathieu F. , White Michael J. , Noble Fergus , Moutasim Karwan A. , Smith Eric , Drew Paul A. , Thomas Gareth J. , Primrose John N. , Blaydes Jeremy P.
Published: September 2010

Background Information. Carcinoma of the oesophagus is the sixth leading cause of cancer death in the western world and is associated with a 5‐year survival of less than 15%. Recent evidence suggests that stromal—epithelial interactions are fundamental in carcinogenesis. The advent of co‐culture techniques permits the investigation of cross‐talk between the stroma and epithelium in a physiological setting. We have characterized a histologically representative oesophageal organotypic model and have used it to compare the most commonly used squamous oesophageal cell line, HET‐1A, with primary oesophageal squamous cells for use in studies of the oesophageal epithelium in vitro.

Results. When grown in an organotypic culture with normal fibroblasts, the oesophageal carcinoma cell lines OE21 (squamous) and OE19 (adenocarcinoma) morphologically resembled the tumour of origin with evidence of stromal invasion and mucus production, respectively. However, HET‐1A cells, which were derived from normal squamous oesophageal cells, appeared dysplastic and failed to display evidence of squamous differentiation. By comparison with primary oesophageal epithelial cells, the HET‐1A cells were highly proliferative and did not express the epithelial markers E‐cadherin or CK5/6 (casein kinase 5/6), or the stratified epithelial marker ΔNp63, but did express the mesenchymal markers vimentin and N‐cadherin.

Conclusion. Studies of epithelial carcinogenesis will benefit from culture systems which allow manipulation of the stromal and epithelial layers independently. We have developed an organotypic culture using primary oesophageal squamous cells and fibroblasts in which a stratified epithelium with a proliferative basal layer that stains strongly for ΔNp63 develops. This model will be suitable for the study of the molecular events in the development of Barrett's oesophagus. The most commonly used normal oesophageal squamous cell line, HET‐1A, does not have the characteristics of normal oesophageal squamous cells and should not be used in models of the normal oesophageal epithelium. Until more representative cell lines are available, future studies in oesophageal cancer will be reliant on the availability and manipulation of primary tissue.
Removal of amino acid, peptide and protein hydroperoxides by reaction with peroxiredoxins 2 and 3
Authors: Peskin Alexander V. , Cox Andrew G. , Nagy Péter , Morgan Philip E. , Hampton Mark B. , Davies Michael J. , Winterbourn Christine C.
Published: September 2010

Prxs (peroxiredoxins) are a ubiquitous family of cysteine-dependent peroxidases that react rapidly with H2O2 and alkyl hydroperoxides and provide defence against these reactive oxidants. Hydroperoxides are also formed on amino acids and proteins during oxidative stress, and they too are a potential cause of biological damage. We have investigated whether Prxs react with amino acid, peptide and protein hydroperoxides, and whether the reactions are sufficiently rapid for these enzymes to provide antioxidant protection against these oxidants. Isolated Prx2, which is a cytosolic protein, and Prx3, which resides within mitochondria, were reacted with a selection of hydroperoxides generated by γ-radiolysis or singlet oxygen, on free amino acids, peptides and proteins. Reactions were followed by measuring the accumulation of disulfide-linked Prx dimers, via non-reducing SDS/PAGE, or the loss of the corresponding hydroperoxide, using quench-flow and LC (liquid chromatography)/MS. All the hydroperoxides induced rapid oxidation, with little difference in reactivity between Prx2 and Prx3. N-acetyl leucine hydroperoxides reacted with Prx2 with a rate constant of 4×104 M−1·s−1. Hydroperoxides present on leucine, isoleucine or tyrosine reacted at a comparable rate, whereas histidine hydroperoxides were ~10-fold less reactive. Hydroperoxides present on lysozyme and BSA reacted with rate constants of ~100 M−1·s−1. Addition of an uncharged derivative of leucine hydroperoxide to intact erythrocytes caused Prx2 oxidation with no concomitant loss in GSH, as did BSA hydroperoxide when added to concentrated erythrocyte lysate. Prxs are therefore favoured intracellular targets for peptide/protein hydroperoxides and have the potential to detoxify these species in vivo.
On a dissipative form of Camassa–Holm equation
Authors: Yu Shengqi , Wang Mingxin
Published: September 2010

In this paper, we consider several problems on the Camassa–Holm equation with a weak dissipation term. First, we establish the local well-posedness result and then we present several new blow-up results and discuss the global existence of the solution for the periodic case. Finally, we examine the persistence of decay properties for the weakly dissipative Camassa–Holm equation, and we prove that any nontrivial classical solution of the equation will not have compact support if its initial data have this property.
Internal symmetry of basic elements in symmetry-based recoupling sequences under magic-angle spinning
Authors: Chou Fang-Chieh , Lee Hsin-Kuan , Chan Jerry C. C.
Published: September 2010

In solid-state NMR, many powerful pulse sequences under the condition of magic-angle spinning can be analyzed on the basis of the C- and R-sequences developed by Levitt and co-workers. It has been speculated for some years that the basic elements commonly used in symmetry-based recoupling pulse sequences have certain kind of internal symmetries. We show by a detailed analysis that a set of internal selection rules does exist for many basic elements. These internal selection rules may allow a more versatile design of CNnν or RNnν sequences when n is an integer or half-integer multiple of N. As an illustration, we have derived the symmetry arguments to rationalize the observation that the C-REDOR pulse sequence can suppress homonuclear dipole-dipole interaction, leading to the design of new windowed basic elements usable for heteronuclear dipolar recoupling with active suppression of homonuclear dipole-dipole interaction. Numerical simulations and experiments measured for [U–C13,N15]-L-alanine have been used to validate our approach. On a more general note, the symmetry rules discussed in this work can also be applied for the design of supercycles.
Versatile apparatus for attosecond metrology and spectroscopy
Authors: Fieß M. , Schultze M. , Goulielmakis E. , Dennhardt B. , Gagnon J. , Hofstetter M. , Kienberger R. , Krausz F.
Published: September 2010

We present the AS-2 Attosecond Beamline at the Joint Laboratory for Attosecond Physics of the Max-Planck-Institut für Quantenoptik and Ludwig-Maximilians-Universität for time resolved pump/probe experiments with attosecond resolution. High harmonic generation and subsequent filtering of the generated extreme ultraviolet (XUV) continuum by means of metal filters and XUV multilayer mirrors serve for the generation of isolated attosecond laser pulses. After high harmonic generation, the remaining fundamental laser pulse is spatially separated from the attosecond XUV pulse, to what is to our knowledge for the first time, by means of a perforated mirror in a Mach–Zehnder interferometer. Active stabilization of this interferometer guarantees the necessary temporal resolution for tracking attosecond dynamics in real time. As a proof-of-principle, photoelectron streaking experiments are performed and experimental techniques for their realization are summarized. Finally we highlight the potential of the presented beamline system for future experiments in comparison with previously demonstrated attosecond beamlines.
Can uniaxial anisotropy be responsible for training in exchange coupled system?
Authors: Paul Amitesh , Mattauch Stefan
Published: September 2010

Training in exchange bias can be related to the field cooled state of the ferromagnet—multidomain or single domain. In a system of coexistent states, realized by coercive field cooling, we could observe usual training for the single domain portion while the multidomain portion remains untrained. This crossover state indicates to the fact that antiferromagnetic uniaxial anisotropy can be made responsible for the training in exchange coupled system where no biaxial anisotropy could exist.
Asymmetries in an obstructed turbulent channel flow
Authors: El Khoury George K. , Pettersen Bjørnar , Andersson Helge I. , Barri Mustafa
Published: September 2010

The asymmetric flow pattern caused by a single thin-plate obstruction in a plane channel has been explored by means of direct numerical simulations. The blockage ratio was 1:2 and the bulk Reynolds number about 5700. In order to mimic an infinitely long channel section upstream of the obstruction, realistic dynamic inflow conditions were provided by a promising technique proposed by Barri et al. [“Inflow conditions for inhomogeneous turbulent flows,” Int. J. Numer. Methods Fluids 60, 227 (2009)]. The fluid downstream of the symmetric obstruction was sucked toward one side where a modestly long region of rather strong recirculating flow was observed. The weaker recirculation bubble formed at the opposite side was 17 times longer than the obstruction height and almost four times the size of the shorter bubble. The overall flow pattern turned out to be rather different from that observed in a similar study of channel flow subjected to periodically repeating obstructions by Makino et al. [“Turbulent structures and statistics in turbulent channel flow with two-dimensional slits,” Int. J. Heat Fluid Flow 29, 602 (2008)]. An anomalous variation of the pressure coefficient was observed with an excessively low pressure below the shorter of the bubbles. A locally high pressure occurred where the deflected jet flow impinges on the wall, whereas another pressure minimum could be associated with the flow acceleration caused by the severe blockage due to the major recirculation bubble. The turbulent fluctuations were suppressed due to the acceleration through the obstruction and high levels of streamwise velocity persisted far downstream. Exceptionally high turbulence levels were observed in the mixing-layers emanating from the two sides of the obstruction. The turbulence in these mixing-layers turned out to be qualitatively and quantitatively different on the two sides and exhibited distinctly different anisotropies.
Diffusion anomaly and dynamic transitions in the Bell–Lavis water model
Authors: Szortyka Marcia M. , Fiore Carlos E. , Henriques Vera B. , Barbosa Marcia C.
Published: September 2010

In this paper we investigate the dynamic properties of the minimal Bell–Lavis (BL) water model and their relation to the thermodynamic anomalies. The BL model is defined on a triangular lattice in which water molecules are represented by particles with three symmetric bonding arms interacting through van der Waals and hydrogen bonds. We have studied the model diffusivity in different regions of the phase diagram through Monte Carlo simulations. Our results show that the model displays a region of anomalous diffusion which lies inside the region of anomalous density, englobed by the line of temperatures of maximum density. Further, we have found that the diffusivity undergoes a dynamic transition which may be classified as fragile-to-strong transition at the critical line only at low pressures. At higher densities, no dynamic transition is seen on crossing the critical line. Thus evidence from this study is that relation of dynamic transitions to criticality may be discarded.
A new ripplon branch in He II
Authors: Tanatarov I. V. , Adamenko I. N. , Nemchenko K. E. , Wyatt A. F. G.
Published: September 2010

We analyse the dispersion relation of ripplons, on the surface of superfluid helium, using the dispersive hydrodynamics approach and find a new ripplon branch. We obtain an analytical equation for the dispersion relation and analytic expressions for the limiting cases. The probabilities of decay of unstable ripplons above the roton gap into rotons are derived. A numerical solution for the ripplon dispersion curve is obtained. A new ripplon branch is found at energies just below the instability point of the bulk spectrum, and is investigated; its stability is discussed.