bluuebunny/crossref_metadata_2025 huggingface dataset:
Reduced activity within the dorsal endogenous orienting of attention network to fearful expressions in youth with disruptive behavior disorders and psychopathic traits
Authors: White Stuart F. , Williams W. Craig , Brislin Sarah J. , Sinclair Stephen , Blair Karina S. , Fowler Katherine A. , Pine Daniel S. , Pope Kayla , Blair R. James
Published: July 2012

Using behavioral and blood oxygen level dependent (BOLD) response indices through functional magnetic resonance imaging (fMRI), the current study investigated whether youths with disruptive behavior disorders (conduct disorder and oppositional defiant disorder) plus psychopathic traits (DBD + PT) show aberrant sensitivity to eye gaze information generally and/or whether they show particular insensitivity to eye gaze information in the context of fearful expressions. The participants were 36 children and adolescents (ages 10–17 years); 17 had DBD + PT and 19 were healthy comparison subjects. Participants performed a spatial attention paradigm where spatial attention was cued by eye gaze in faces displaying fearful, angry, or neutral affect. Eye gaze sensitivity was indexed both behaviorally and as BOLD response. There were no group differences in behavioral response: both groups showed significantly faster responses if the target was in the congruent spatial direction indicated by eye gaze. Neither group showed a Congruence × Emotion interaction; neither group showed an advantage from the displayer's emotional expression behaviorally. However, the BOLD response revealed a significant Group × Congruence × Emotion interaction. The comparison youth showed increased activity within the dorsal endogenous orienting network (superior parietal lobule and inferior parietal sulcus) for fearful congruent relative to incongruent trials relative to the youth with DBD + PT. The results are discussed with reference to current models of DBD + PT and possible treatment innovations.
Covert antisocial behavior, peer deviancy training, parenting processes, and sex differences in the development of antisocial behavior during childhood
Authors: Snyder James J. , Schrepferman Lynn P. , Bullard Lisha , McEachern Amber D. , Patterson Gerald R.
Published: July 2012

Two longitudinal studies were used to examine the occurrence and consequences of peer deviancy training during childhood and the relative role of early covert antisocial behavior in risk for antisocial behavior in early adolescence. Peer deviancy training was apparent in a sample of at-risk first grade children, and it showed persistence and increased prevalence across the school year. Peer deviancy training, peer rejection, and unskilled parenting made additive contributions to the development of antisocial behavior during kindergarten and first grade and to antisocial behavior in fourth grade. Skilled parenting partially mitigated the association of peer deviancy training with antisocial behavior for boys. The appearance and growth of covert antisocial behavior was a predictor of fourth grade antisocial for boys and girls, more so than aggressive and overt antisocial behavior. Peer deviancy training and early covert antisocial behavior were key pathways to girls' antisocial behavior in fourth grade, and they complemented the roles of peer rejection and overt antisocial behavior for boys. The relationships of parenting and peer processes to trajectories of antisocial behavior were similar for boys and girls; but boys showed higher levels of antisocial behavior, were more involved in peer deviancy training, and were more likely to experience peer rejection.
The impact of a family-centered intervention on the ecology of adolescent antisocial behavior: Modeling developmental sequelae and trajectories during adolescence
Authors: Van Ryzin Mark J. , Dishion Thomas J.
Published: July 2012

This study used an experimental, longitudinal field trial involving random assignment to the Family Check-Up (FCU) to explore the social ecology of adolescent antisocial behavior. A sample of 998 youths and their families was followed from early to late adolescence (age 12 to 18–19). In the intervention condition, 115 families (23%) elected to receive the FCU. In general, random assignment to the FCU in middle school was associated with reductions in late adolescence antisocial behavior (age 18–19). Variable-centered analyses revealed that the effects were mediated by reductions in family conflict from early to middle adolescence (age 12–15). The link between family conflict and antisocial behavior in turn was mediated by association with deviant peers at age 17; parental monitoring at age 17 was also influential but did not attain the status of a mediator. Person-oriented analyses suggested that the FCU was associated with declining trajectories of family conflict and rising trajectories of parental monitoring but was not associated with trajectories of deviant peer association. A dual-trajectory analysis indicated that the pathways to adolescent antisocial behavior were myriad and varied, suggesting new directions for developmental and intervention research.
Retinol improves in vitro oocyte nuclear maturation under heat stress in heifers
Authors: Maya-Soriano M.J. , Taberner E. , López-Béjar M.
Published: July 2012

Heat stress (HS) is especially harmful for bovine ovarian follicle development and oocyte competence. Furthermore, HS causes premature aging in oocytes due to high levels of reactive oxygen species (ROS), involved in the harmful effects over the oocyte maturation and the steroidogenic activity of follicular cells. In this study, the presumptive protective effects of antioxidant agents on heat-stressed oocytes were evaluated. Heifer oocytes were matured for 22 h under control (38°C) and HS conditions (41.5°C at 18–21 h of maturation). For each oocyte, nuclear stage and cortical granule (CG) distribution were evaluated. Steroidogenic activity of cumulus cells was also recorded. The antioxidant agents used in the study were: retinol (1.43 μg/ml), retinyl (0.28 μg/ml) and oleic acid (0.05 mg/ml). Based on a chi-squared test (P < 0.05), HS affected negatively the metaphase II (MII) progression and produced a premature CG exocytosis. Retinol improved the oocyte MII progression. However, retinyl and oleic acid, at the concentrations used in this study, could not counteract adverse effects of HS. A decrease in progesterone and increase in estradiol availability were observed when retinyl and oleic acid were supplemented to the maturation medium, respectively. In conclusion, retinol proved to be valuable in heat-stressed oocytes protecting nuclear maturation.
Do embryonic polar bodies commit suicide?
Authors: Fabian Dušan , Čikoš Štefan , Rehák Pavol , Koppel Juraj
Published: July 2012

The extrusion and elimination of unnecessary gametic/embryonic material is one of the key events that determines the success of further development in all living organisms. Oocytes produce the first polar body to fulfill the maturation process just before ovulation, and release the second polar body immediately after fertilization. The aim of this study was to compile a physiological overview of elimination of polar bodies during early preimplantation development in mice. Our results show that three-quarters of the first polar bodies were lost even at the zygotic stage; the 4-cell stage embryos contained only one (second) polar body, and the elimination of second polar bodies proceeded continuously during later development. Both first and second polar bodies showed several typical features of apoptosis: phosphatidylserine redistribution (observed for the first time in the first polar body), specific DNA degradation, condensed nuclear morphology, and inability to exclude cationic dye from the nucleus during the terminal stage of the apoptotic process. Caspase-3 activity was recorded only in the second polar body. From the morphological point of view, mouse polar bodies acted very similarly to damaged embryonic cells which have lost contact with their neighboring blastomeres. In conclusion, polar bodies possess all the molecular equipment necessary for triggering and executing an active suicide process. Furthermore, similarly as in dying embryonic cells, stressing external conditions (culture in vitro) might accelerate and increase the incidence of apoptotic elimination of the polar bodies in embryos.
Different preferences of IVF and SCNT bovine embryos for culture media
Authors: Xiong Xian-rong , Wang Li-jun , Wang Yong-sheng , Hua Song , Zi Xiang-dong , Zhang Yong
Published: July 2012

The preference of fertilized (IVF) and somatic cell nuclear transfer (SCNT) presumptive zygotes for different media when cultured in vitro to the blastocyst stage was evaluated in this study. The experiment comprised two zygote production methods (IVF and SCNT) × two culture media (mSOF and G1.5/G2.5) factorial design in which culture droplets that contained approximate 30 presumptive zygotes formed the experimental plots for the assessment of cleavage and blastocyst development. There were 15 to 20 replicates (culture droplets) per treatment combination. Sub-samples 30 to 41 of the blastocysts produced were assessed for cell number and cell apoptosis. A further 10 blastocysts per treatment combination were used for quantitative real-time polymerase chain reaction (RT-PCR) to evaluate the relative abundance of Hsp70 and Bax mRNA. Presumptive zygotes produced by IVF were developmentally more competent than SCNT zygotes in terms of cleavage rate (66.9 vs. 57.0%; P < 0.05) and blastocyst development rates (blastocysts of presumptive zygotes 29.7 vs. 24.8%; blastocysts of cleaved zygotes 44.4 vs. 36.6%; P < 0.05). Over both zygote production systems, however, the results were similar whether culture was in mSOF or in G1.5/G2.5 media for cleavage rate (63.2 vs. 62.4%; P > 0.05) and blastocyst development rate (blastocysts of presumptive zygotes 26.4 vs. 25.7%; P > 0.05; blastocysts of cleaved zygotes 41.8 vs. 41.2%; P > 0.05). There was, however, a significant interaction between the method of zygote production and culture medium for the apoptotic index of blastocysts. The interaction was such that IVF-produced zygotes cultured in mSOF had a lower apoptotic index compared with those cultured in G1.5/G2.5 (4.7 ± 1.2% vs. 9.8 ± 0.9%; P < 0.05) whereas SCNT zygotes had a higher apoptotic index when cultured in mSOF compared with those cultured in G1.5/G2.5 (11.9 ± 1.5% vs. 4.5 ± 1.2%; P < 0.05). Moreover, RT-PCR analysis showed that embryos from IVF-produced zygotes cultured in mSOF had a lower expression level of stress-related and apoptosis genes (Hsp70 and Bax) than those cells cultured in G1.5/G2.5 medium, while SCNT-derived embryos cultured in mSOF had a higher expression level of these genes than those embryos cultured in G1.5/G2.5 medium. The results of this study show that bovine IVF- and SCNT-produced presumptive zygotes have different nutrient requirements for in vitro culture to the blastocyst stage of development. IVF-derived zygotes have a preference for mSOF as the culture medium whereas the G1.5/G2.5 medium is more suitable for the culture of bovine SCNT-derived zygotes.
A comprehensive method for the conservation of mouse strains combining natural breeding, sperm cryopreservation and assisted reproductive technology
Authors: Li Dun-Gao , Zhu Yan , Li He-Ping , Chen Xue-Jin , Jiang Man-Xi
Published: July 2012

The maintenance and preservation of strains of mice used in biomedical research presents a unique challenge to individual investigators and research institutions. The goal of this study was to assess a comprehensive system for mouse strain conservation through a combination of natural mating, sperm cryopreservation and assisted reproductive technology. Our strategy was based on the collection and cryopreservation of fresh epididymal sperm from male mice by semi-vasectomy; these mice were then naturally mated for breeding purposes. If no satisfactory results were obtained from natural breeding, then the cryopreserved sperm were used for in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI); resultant embryos were then transferred into pseudopregnant-recipient female mice. Our results show that some semi-vasectomized mouse strains can be conserved by natural breeding, and that sterile males can be compensated for through the use of IVF and ICSI technology. As such, we believe this system is suitable for the purpose of strain conservation, allowing the continuation of natural breeding with the safeguard of assisted reproduction available.
Injuries in pacu embryos (Piaractus mesopotamicus) after freezing and thawing
Authors: Neves Patrícia Ribeiro , Ribeiro Ricardo Pereira , Streit Danilo Pedro , Natali Maria Raquel M. , Fornari Darci Carlos , Santos Alexandra Inês , Godoy Leandro C.
Published: July 2012

Although the sperm cryopreservation of freshwater and marine teleosts has been feasible for years, the cryopreservation of some fish embryos still remains elusive. Thus, the objective of this experiment was to analyze the embryo morphology after freezing and thawing 40 embryos of Piaractus mesopotamicus immersed into methanol and ethylene glycol, both at 7, 10 and 13% plus 0.1 M sucrose for 10 min. Soon after thawing, three embryos were treated with historesin, stained with hematoxylin–eosin and analyzed under an optical microscope. From every treatment, one palette containing embryos was thawed and incubated, but none of the eggs hatched. Samples containing two embryos were immersed into 10% methanol or 10% ethylene glycol both in association with sucrose, and embryos immersed into only water or sucrose solution were frozen, processed and analyzed using scanning electron microscopy (SEM). In both cases, the control group was immersed into only water. Although the embryos had the chorion, vitello, yolk syncytial layer and blastoderm, all of them were found altered under the optical microscope and by SEM. The chorion was irregular and injured; there was no individuality in the yolk granules; the yolk syncytial layer had an irregular shape, thickness and size; the blastoderm showed injuries in the nucleus shape and sometimes was absent; the blastoderm was located in atypical areas and absent in some embryos. In conclusion, no treatment was effective in preserving the embryos, and none of the embryos avoided injury from intracellular ice formation. These morphological injuries during the freezing process made the P. mesopotamicus embryos unfeasible for hatching.
CONTRACTUALISM'S (NOT SO) SLIPPERY SLOPE
Authors: James Aaron
Published: July 2012

Familiar questions about whether or how far to impose risks of harm for social benefit present a fundamental dilemma for contractualist moral theories. If contractualism allows “ex post” objections by considering actual outcomes, it becomes difficult to justify the risks created by most public policy, leaving contractualism at odds with moral commonsense in much the way utilitarianism is. But if contractualism instead takes a fully “ex ante” form by considering onlyexpectedoutcomes, it becomes unclear how it recommends something other than aggregative cost-benefit decision-making. Focusing on T.M. Scanlon's version, this paper develops this basic choice of interpretation and recommends theex anteversion. The paper explains how contractualism is inconsistent with John Harsanyi–style utilitarianism and how contractualism supplies a principled framework for walking a careful line between the “bad aggregation” characteristic of utilitarianism and the “good aggregation” that is both unavoidable and fully appropriate in public life.
The impact of shadow prices and farmers' impatience on the allocation of a multipurpose renewable resource in Ethiopia
Authors: Teklewold Hailemariam
Published: July 2012

In a mixed farming system in which farmyard manure (FYM) is considered an important multipurpose renewable resource that can be used to enhance soil organic matter, provide additional income and supply household energy, soil fertility depletion could take place within the perspective of the household allocation pattern of FYM. This paper estimates a system of FYM allocation regressions to examine the role of returns to FYM and farmers' impatience on the propensity to allocate FYM to different uses. We parameterize the model using data from a sample of 493 households in Ethiopia. Results indicate a heightened incentive for diverting FYM from farming to marketing for burning outside the household when returns to selling FYM and the farmer's discount rate are high. These reveal the need for policies that will help to reduce farmers' impatience and encourage the substitution of alternative energy sources to increase the use of FYM as a sustainable land management practice.
Market participation, on-farm crop diversity and household welfare: micro-evidence from Kenya
Authors: Asfaw Solomon , Lipper Leslie , Dalton Timothy J. , Audi Patrick
Published: July 2012

This paper examines determinants of output and input market participation. It employs propensity score matching techniques to evaluate the impact of market participation on pigeonpea diversity and household welfare, using cross-sectional data of 333 households from Kenya. Results show that input and output market participation decisions are quite distinct. Output market participation is influenced by household demographics, farm size and radio ownership, while input market participation is determined by farm size, bicycle ownership and access to a salaried income. The findings reveal a positive and significant impact of output market participation on pigeonpea diversity, while input market participation had a negative and significant impact on diversity. The results indicate that output market participants have significantly higher food security status than non-participants, in line with the general findings of the literature. However, no significant impact is found between indicators of household welfare and input market participation.
Brazilian research on extremophiles in the context of astrobiology
Authors: Duarte Rubens T. D. , Nóbrega Felipe , Nakayama Cristina R. , Pellizari Vivian H.
Published: July 2012

Extremophiles are organisms adapted to grow at extreme ranges of environmental variables, such as high or low temperatures, acid or alkaline medium, high salt concentration, high pressures and so forth. Most extremophiles are micro-organisms that belong to the Archaea and Bacteria domains, and are widely spread across the world, which include the polar regions, volcanoes, deserts, deep oceanic sediments, hydrothermal vents, hypersaline lakes, acid and alkaline water bodies, and other extreme environments considered hostile to human life. Despite the tropical climate, Brazil has a wide range of ecosystems which include some permanent or seasonally extreme environments. For example, the Cerrado is a biome with very low soil pH with high Al+3concentration, the mangroves in the Brazilian coast are anaerobic and saline, Pantanal has thousands of alkaline–saline lakes, the Caatinga arid and hot soils and the deep sea sediments in the Brazilian ocean shelf. These environments harbour extremophilic organisms that, coupled with the high natural biodiversity in Brazil, could be explored for different purposes. However, only a few projects in Brazil intended to study the extremophiles. In the frame of astrobiology, for example, these organisms could provide important models for defining the limits of life and hypothesize about life outside Earth. Brazilian microbiologists have, however, studied the extremophilic micro-organisms inhabiting non-Brazilian environments, such as the Antarctic continent. The experience and previous results obtained from the Brazilian Antarctic Program (PROANTAR) provide important results that are directly related to astrobiology. This article is a brief synopsis of the Brazilian experience in researching extremophiles, indicating the most important results related to astrobiology and some future perspectives in this area.
Decomposition of effects of social security on private savings
Authors: HONG MINKI
Published: July 2012

The main aim of this paper is to decompose the effects of social security on private savings and quantify to what extent each factor that impacts saving behavior account for the effects of social security. For this purpose, I estimate a stochastic dynamic model in which households facing income and survival uncertainty choose optimal levels of consumption, asset holdings and labor supply. In this model, social security pensions reduce private assets by less than 10%. Bequest and precautionary savings motives are the main reasons of this partial offset. Uncertainty on future benefits has no role to play on the effect.
Organic carbon burial rates in mangrove sediments: Strengthening the global budget
Authors: Breithaupt Joshua L. , Smoak Joseph M. , Smith Thomas J. , Sanders Christian J. , Hoare Armando
Published: July 2012

Mangrove wetlands exist in the transition zone between terrestrial and marine environments and as such were historically overlooked in discussions of terrestrial and marine carbon cycling. In recent decades, mangroves have increasingly been credited with producing and burying large quantities of organic carbon (OC). The amount of available data regarding OC burial in mangrove soils has more than doubled since the last primary literature review (2003). This includes data from some of the largest, most developed mangrove forests in the world, providing an opportunity to strengthen the global estimate. First‐time representation is now included for mangroves in Brazil, Colombia, Malaysia, Indonesia, China, Japan, Vietnam, and Thailand, along with additional data from Mexico and the United States. Our objective is to recalculate the centennial‐scale burial rate of OC at both the local and global scales. Quantification of this rate enables better understanding of the current carbon sink capacity of mangroves as well as helps to quantify and/or validate the other aspects of the mangrove carbon budget such as import, export, and remineralization. Statistical analysis of the data supports use of the geometric mean as the most reliable central tendency measurement. Our estimate is that mangrove systems bury 163 (+40; −31) g OC m−2 yr−1 (95% C.I.). Globally, the 95% confidence interval for the annual burial rate is 26.1 (+6.3; −5.1) Tg OC. This equates to a burial fraction that is 42% larger than that of the most recent mangrove carbon budget (2008), and represents 10–15% of estimated annual mangrove production. This global rate supports previous conclusions that, on a centennial time scale, 8–15% of all OC burial in marine settings occurs in mangrove systems.
The role of groundwater in the Amazon water cycle: 1. Influence on seasonal streamflow, flooding and wetlands
Authors: Miguez‐Macho Gonzalo , Fan Ying
Published: July 2012

Observational studies across the Amazon report a common occurrence of shallow water table in lowland valleys and groundwater‐surface water exchange from small headwater catchments to large floodplains. In this study, we assess groundwater's role in the Amazon surface water dynamics using a continental‐scale coupled groundwater‐surface water model (LEAF‐Hydro‐Flood) forced by ERA‐Interim reanalysis, at 2 km and 4 min resolution over 11 years (2000–2010). The simulation is validated with observed streamflow, water table depth and flooding extent. A parallel simulation without groundwater is conducted to isolate its effect. Our findings support the following hypotheses. First, in the headwater catchments, groundwater dominates streamflow; the observed variations in its dominance across the Amazon can be explained by the varying water table depth. Second, over large floodplains, there are two‐way exchanges between floodwater and groundwater as infiltration in the wet season and seepage in the dry season, and the direction and magnitude are controlled by the water table depth. Third, the Amazon harbors large areas of wetlands that are rarely under floodwater and difficult to observe by remote sensing, but are maintained by a persistently shallow water table. Fourth, due to its delayed and muted response to rainfall, groundwater seepage persists in the dry season, buffering surface waters through seasonal droughts. Our simulations shed new lights on the spatial‐temporal structures of the hidden subsurface hydrologic pathways across the Amazon and suggest possible mechanisms whereby groundwater actively participates in the Amazon water‐carbon cycle such as CO2 outgassing from groundwater seeps and CH4 emission from groundwater‐supported wetlands.
Identifying the Neural Correlates of Executive Functions in Early Cerebral Microangiopathy: A Combined VBM and DTI Study
Authors: Quinque Eva M , Arélin Katrin , Dukart Juergen , Roggenhofer Elisabeth , Streitbuerger Daniel-P , Villringer Arno , Frisch Stefan , Mueller Karsten , Schroeter Matthias L
Published: July 2012

Cerebral microangiopathy (CMA) has been associated with executive dysfunction and fronto-parietal neural network disruption. Advances in magnetic resonance imaging allow more detailed analyses of gray (e.g., voxel-based morphometry—VBM) and white matter (e.g., diffusion tensor imaging—DTI) than traditional visual rating scales. The current study investigated patients with early CMA and healthy control subjects with all three approaches. Neuropsychological assessment focused on executive functions, the cognitive domain most discussed in CMA. The DTI and age-related white matter changes rating scales revealed convergent results showing widespread white matter changes in early CMA. Correlations were found in frontal and parietal areas exclusively with speeded, but not with speed-corrected executive measures. The VBM analyses showed reduced gray matter in frontal areas. All three approaches confirmed the hypothesized fronto-parietal network disruption in early CMA. Innovative methods (DTI) converged with results from conventional methods (visual rating) while allowing greater spatial and tissue accuracy. They are thus valid additions to the analysis of neural correlates of cognitive dysfunction. We found a clear distinction between speeded and nonspeeded executive measures in relationship to imaging parameters. Cognitive slowing is related to disease severity in early CMA and therefore important for early diagnostics.
Cortical Spreading Depression Shifts Cell Fate Determination of Progenitor Cells in the Adult Cortex
Authors: Tamura Yasuhisa , Eguchi Asami , Jin Guanghua , Sami Mustafa M , Kataoka Yosky
Published: July 2012

Cortical spreading depression (SD) is propagating neuronal and glial depolarization and is thought to underly the pathophysiology of migraine. We have reported that cortical SD facilitates the proliferative activity of NG2-containing progenitor cells (NG2 cells) that give rise to oligodendrocytes and immature neurons under the physiological conditions in the adult mammalian cortex. Astrocytes have an important role in the maintenance of neuronal functions and alleviate neuronal damage after intense neuronal excitation, including SD and seizures. We here investigated whether SD promotes astrocyte generation from NG2 cells following SD stimuli. Spreading depression was induced by epidural application of 1 mol/L KCl solution in adult rats. We investigated the cell fate of NG2 cells following SD-induced proliferation using 5′-bromodeoxyuridine labeling and immunohistochemical analysis. Newly generated astrocytes were observed only in the SD-stimulated cortex, but not in the contralateral cortex or in normal cortex. The astrocytes were generated from proliferating NG2 cells. Astrogenesis depended on the number of SD stimuli, and was accompanied by suppression of oligodendrogenesis. These observations indicate that the cell fate of NG2 cells was shifted from oligodendrocytes to astrocytes depending on SD stimuli, suggesting activity-dependent tissue remodeling for maintenance of brain functions.
High resolution spectral analysis of oxygen. II. Rotational spectra of a1Δg  O2 isotopologues
Authors: Drouin Brian J. , Gupta Harshal , Yu Shanshan , Miller Charles E. , Müller Holger S. P.
Published: July 2012

As part of a comprehensive review on molecular oxygen spectroscopy, we have measured rotational spectra of isotopic forms of molecular oxygen in its a1Δg electronic state with high-resolution terahertz spectroscopy. The data are recorded in close proximity to predicted positions. Due to the high resolution and good signal-to-noise ratio, the fundamental hyperfine parameters eQq and CI are determinable for 17O-substituted species for the first time. A refined nuclear spin orbit coupling constant, a = −211.9328(283) MHz, was determined, and is roughly two orders of magnitude more precise than values determined from near infrared spectroscopy or electron spin resonance studies. Vibrationally excited oxygen in the a1Δg electronic state was also observable with small signal levels for many of the rotational transitions.
High resolution spectral analysis of oxygen. I. Isotopically invariant Dunham fit for the $X^3 {\rm \Sigma }_g^ -$X3Σg−, a1Δg, $b^1 {\rm \Sigma }_g^ +$b1Σg+ states
Authors: Yu Shanshan , Miller Charles E. , Drouin Brian J. , Müller Holger S. P.
Published: July 2012

We have developed a simultaneous global fit to the MW, THz, infrared, visible, and UV transitions of all six oxygen isotopologues, 16O16O, 16O17O, 16O18O, 17O17O, 17O18O, 18O18O, with the objective of predicting all transitions below the O(3P) + O(3P) dissociation threshold as well as the $B^3 {\rm \Sigma }_u^ -$B3Σu− state from O(3P)+O(1D) within state-of-the-art experimental uncertainty. Here, we report an isotopically invariant Dunham fit for the lowest three electronic states, $X^3 {\rm \Sigma }_g^ -$X3Σg−, a1Δg, and $b^1 {\rm \Sigma }_g^ +$b1Σg+. Experimental transition frequencies involving these three states of all six O2 isotopologues were critically reviewed and incorporated into the analysis. For the 16O16O isotopologue, experimental data sample vibrational states v = 0−31 for $X^3 {\rm \Sigma }_g^ -$X3Σg−, v = 0−10 for a1Δg, and v = 0−12 for $b^1 {\rm \Sigma }_g^ +$b1Σg+. To the best of our knowledge, this is the first analysis that simultaneously fits spectra from all six O2 isotopologues.
Existence of the thermodynamic limit for disordered quantum Coulomb systems
Authors: Blanc Xavier , Lewin Mathieu
Published: July 2012

Following a recent method introduced by Hainzl, Solovej, and Lewin, we prove the existence of the thermodynamic limit for a system made of quantum electrons, and classical nuclei whose positions and charges are randomly perturbed in an ergodic fashion. All the particles interact through Coulomb forces.
Stability of electrically induced-polarization in poly (L-lactic) acid for bone regeneration
Authors: Barroca Nathalie , Vilarinho Paula M. , Fernandes Maria Helena V. , Sharma Pankaj , Gruverman Alexei
Published: July 2012

This paper describes the decay kinetics of electrically induced polarization of poly(L-lactic) acid (PLLA) via piezoresponse force microscopy. Two crystalline forms of PLLA (α and α′) were electrically poled at different temperatures (room and above glass transition). Poling at temperatures above glass transition allowed obtaining polarization stable up to 10 days for both forms. This period is enough to trigger and maintain proteins adhesion and cells proliferation, if PLLA is used as a platform for tissue growth. When poled at room temperature, both structures lose polarization after a short time (minutes to hours) being polarization in α PLLA stable for longer time.
Temperature induced conversion from surface to “bulk” sites in Eu3+-impregnated CeO2 nanocrystals
Authors: Tiseanu Carmen , Parvulescu Vasile I. , Sanchez-Dominguez Margarita , Boutonnet Magali
Published: July 2012

Evolution with calcination temperature of Eu3+ sites in CeO2 nanocrystals is investigated by time-resolved photoluminescence spectroscopy. In the as-synthesized Eu3+ impregnated CeO2, most of Eu3+ ions reside on surface (S) sites. The Eu3+emission in S sites is broad and short-lived (τ = 240 μs) being dominated by the electric dipole (ED) 5D0-7F2 emission with little evidence for clustering. After calcination (between 500 and 1300 °C), Eu3+ is distributed on surface, cubic and up to three additional crystalline sites. Surface type emission could be detected until 1100 °C. In cubic sites, Eu3 substitute for the lattice Ce4+ with Oh symmetry (O sites). The emission of Eu3+ in O sites is characterized by relative long-lived (τ = 1.8–2 ms) and ultra-narrow (FWHM = 7 cm−1) magnetic dipole (MD) 5D0-7F1 emission centered at ∼591 nm. Three more crystalline sites are attributed to the oxygen vacancy charge-compensated defects: trigonal with C3v symmetry (C1 sites) and C2 and C3 sites with C2v or lower symmetry. Eu3+ in C1 sites exhibits predominant ED 5D0-7F2 emission centered at ∼610 and 632 nm with lifetime of 0.85–1 ms. The C1 sites are assigned to Eu3+-(oxygen vacancy)-associated cubic sites. The O2− to Ce4+ electronic charge-transfer band sensitizes preferentially the Eu3+ emission in O and, to a less extent, C1 sites but not the S sites. Overall, the results show that the oxygen vacancies are distributed around both Eu3+ and Ce4+ and the Eu3+-oxygen vacancy interaction mode as nearest-neighbour or next-nearest-neighbour depends on the calcination temperature.
Lattice strain of osmium diboride under high pressure and nonhydrostatic stress
Authors: Kavner Abby , Weinberger Michelle B. , Shahar Anat , Cumberland Robert W. , Levine Jonathan B. , Kaner Richard B. , Tolbert Sarah H.
Published: July 2012

The lattice strain behavior of osmium diboride—a member of a group of third-row transition metal borides associated with hard/superhard behavior—has been studied using radial diffraction in a diamond anvil cell under high pressure and non-hydrostatic stress. We interpret the average values of the measured lattice strains as a lower-bound to the lattice-plane dependent yield strengths using existing estimates for the elastic constants of OsB2, with a yield strength of 11 GPa at 27.5 GPa of hydrostatic pressure. The measured differential lattice strains show significant plane-dependent anisotropy, with the (101) lattice plane showing the largest differential strain and the (001) lattice plane showing the least strain. At the highest pressure, the a-axis develops a larger compressive strain and supports a larger differential strain than either the b or c axes. This causes an increase in the c/a ratio and a decrease in the a/b ratio especially in the maximum stress direction. The large strength anisotropy of this material points to possible ways to modulate directional mechanical properties by taking advantage of the interplay between aggregate polycrystalline texture with directional mechanical properties.
Dynamics of a galactic Hamiltonian system
Authors: Lacomba Ernesto A. , Llibre Jaume
Published: July 2012

We study an even polynomial potential which appears in the study of the galactic dynamics. We prove the existence of four families of periodic orbits in every positive energy level, and we compute an analytic approximation of them. Using such periodic orbits we provide information about the non-integrability of this Hamiltonian system.
Asymptotic stability of small gap solitons in nonlinear Dirac equations
Authors: Pelinovsky Dmitry E. , Stefanov Atanas
Published: July 2012

We prove dispersive decay estimates for the one-dimensional Dirac operator and use them to prove asymptotic stability of small gap solitons in the nonlinear Dirac equations with quintic and higher-order nonlinear terms.
Heavy ion beam probe advances from the first installation of the diagnostic on an RFP (invited)
Authors: Demers D. R. , Fimognari P. J.
Published: July 2012

Heavy ion beam probes have been installed on a variety of toroidal devices, but the first and only application on a reversed field pinch is the diagnostic on the Madison Symmetric Torus. Simultaneous measurements of spatially localized equilibrium potential and fluctuations of density and potential, previously inaccessible in the core of the reversed field pinch (RFP), are now attainable. These measurements reflect the unique strength of the heavy ion beam probe (HIBP) diagnostic. They will help determine the characteristics and evolution of electrostatic fluctuations and their role in transport, and determine the relation of the interior electric field and flows. Many aspects of the RFP present original challenges to HIBP operation and inference of plasma quantities. The magnetic field contributes to a number of the issues: the comparable magnitudes of the toroidal and poloidal fields and edge reversal result in highly three-dimensional beam trajectories; partial generation of the magnetic field by plasma current cause it and hence the beam trajectories to vary with time; and temporal topology and amplitude changes are common. Associated complications include strong ultraviolet radiation and elevated particle losses that can alter functionality of the electrostatic systems and generate noise on the detectors. These complexities have necessitated the development of new operation and data analysis techniques: the implementation of primary and secondary beamlines, adoption of alternative beam steering methods, development of higher precision electrostatic system models, refinement of trajectory calculations and sample volume modeling, establishment of stray particle and noise reduction methods, and formulation of alternative data analysis techniques. These innovative methods and the knowledge gained with this system are likely to translate to future HIBP operation on large scale stellarators and tokamaks.
Long-time asymptotics of the periodic Toda lattice under short-range perturbations
Authors: Kamvissis Spyridon , Teschl Gerald
Published: July 2012

We compute the long-time asymptotics of periodic (and slightly more generally of algebro-geometric finite-gap) solutions of the doubly infinite Toda lattice under a short-range perturbation. In particular, we prove that the perturbed lattice asymptotically approaches a modulated lattice. More precisely, let g be the genus of the hyperelliptic curve associated with the unperturbed solution. We show that, apart from the phenomenon of solitons travelling in a quasi-periodic background, the n/t-pane contains g + 2 areas where the perturbed solution is close to a finite-gap solution on the same isospectral torus. In between there are g + 1 regions where the perturbed solution is asymptotically close to a modulated lattice which undergoes a continuous phase transition (in the Jacobian variety) and which interpolates between these isospectral solutions. In the special case of the free lattice (g = 0), the isospectral torus consists of just one point and we recover the known result. Both the solutions in the isospectral torus and the phase transition are explicitly characterized in terms of Abelian integrals on the underlying hyperelliptic curve. Our method relies on the equivalence of the inverse spectral problem to a vector Riemann–Hilbert problem defined on the hyperelliptic curve and generalizes the so-called nonlinear stationary phase/steepest descent method for Riemann–Hilbert problem deformations to Riemann surfaces.
Vortex tube reconnection at Re = 104
Authors: van Rees Wim M. , Hussain Fazle , Koumoutsakos Petros
Published: July 2012

We present simulations of the long-time dynamics of two anti-parallel vortex tubes with and without initial axial flow, at Reynolds number Re = Γ/ν = 104. Simulations were performed in a periodic domain with a remeshed vortex method using 785 × 106 particles. We quantify the vortex dynamics of the primary vortex reconnection that leads to the formation of elliptical rings with axial flow and report for the first time a subsequent collision of these rings. In the absence of initial axial flow, a −5/3 slope of the energy spectrum is observed during the first reconnection of the tubes. The resulting elliptical vortex rings experience a coiling of their vortex lines imparting an axial flow inside their cores. These rings eventually collide, exhibiting a −7/3 slope of the energy spectrum. Studies of vortex reconnection with an initial axial flow exhibit also the −7/3 slope during the initial collision as well as in the subsequent collision of the ensuing elliptical vortex rings. We quantify the detailed vortex dynamics of these collisions and examine the role of axial flow in the breakup of vortex structures.
Role of alkali cations for the excited state dynamics of liquid water near the surface
Authors: Buchner Franziska , Ritze Hans-Hermann , Beutler Marcus , Schultz Thomas , Hertel Ingolf V. , Lübcke Andrea
Published: July 2012

Time-resolved liquid jet photoelectron spectroscopy was used to explore the excited state dynamics at the liquid water surface in the presence of alkali cations. The data were evaluated with the help of ab initio calculations on alkali-water clusters and an extension of these results on the basis of the dielectric continuum model: 160 nm, sub-20 fs vacuum ultraviolet pulses excite water molecules in the solvent shell of Na+ or K+ cations and evolve into a transient hydrated complex of alkali-ion and electron. The vertical ionization energy of this transient is about 2.5 eV, significantly smaller than that of the solvated electron.
Infrared spectroscopy of copper-resveratrol complexes: A joint experimental and theoretical study
Authors: Chiavarino B. , Crestoni M. E. , Fornarini S. , Taioli S. , Mancini I. , Tosi P.
Published: July 2012

Infrared multiple-photon dissociation spectroscopy has been used to record vibrational spectra of charged copper-resveratrol complexes in the 3500–3700 cm−1 and 1100–1900 cm−1 regions. Minimum energy structures have been determined by density functional theory calculations using plane waves and pseudopotentials. In particular, the copper(I)-resveratrol complex presents a tetra-coordinated metal bound with two carbon atoms of the alkenyl moiety and two closest carbons of the adjoining resorcinol ring. For these geometries vibrational spectra have been calculated by using linear response theory. The good agreement between experimental and calculated IR spectra for the selected species confirms the overall reliability of the proposed geometries.
Development of a time-resolved attenuated total reflectance spectrometer in far-ultraviolet region
Authors: Morisawa Yusuke , Higashi Noboru , Takaba Kyoko , Kariyama Naomi , Goto Takeyoshi , Ikehata Akifumi , Ozaki Yukihiro
Published: July 2012

A far-ultraviolet transient absorption spectrometer based on time-resolved attenuated total reflectance (ATR) has been developed and tested for aqueous solutions of phenol and tryptophan in the region 170–185 nm. In this region, a stable tunable laser was not available, and therefore, white light from a laser-driven Xe lamp source was used. The time resolution, which was determined by the time response of a continuous light detector, was 40 ns. A new ATR cell where a sample liquid is exchanged continuously by a flow system was designed to reduce efficiently the stray light from the excitation light. We have tested the performance of the instrument by using aqueous solutions of phenol and tryptophan, whose photochemistry is already well known. Phenol and tryptophan have very strong absorptions due to a π–π* transition near 180 nm. Even for dilute solutions (10−3 mol dm−3), we could observe decreases in their concentrations due to photochemistry that occurred upon their irradiation with a fourth harmonic generation laser pulse produced by an Nd:YAG laser. The sensitivity of the spectrometer was about 10−4 abs, which corresponded to a concentration variation of 10−3 mol dm−3 for phenol and tryptophan.
Consistent and transferable coarse-grained model for semidilute polymer solutions in good solvent
Authors: D’Adamo Giuseppe , Pelissetto Andrea , Pierleoni Carlo
Published: July 2012

We present a coarse-grained model for linear polymers with a tunable number of effective atoms (blobs) per chain interacting by intra- and intermolecular potentials obtained at zero density. We show how this model is able to accurately reproduce the universal properties of the underlying solution of athermal linear chains at various levels of coarse-graining and in a range of chain densities which can be widened by increasing the spatial resolution of the multiblob representation, i.e., the number of blobs per chain. The present model is unique in its ability to quantitatively predict thermodynamic and large scale structural properties of polymer solutions deep in the semidilute regime with a very limited computational effort, overcoming most of the problems related to the simulations of semidilute polymer solutions in good solvent conditions.
Efficient method for quantum calculations of molecule-molecule scattering properties in a magnetic field
Authors: Suleimanov Yu. V. , Tscherbul T. V. , Krems R. V.
Published: July 2012

We show that the cross sections for molecule-molecule collisions in the presence of an external field can be computed efficiently using a total angular momentum basis, defined either in the body-fixed frame or in the space-fixed coordinate system. This method allows for computations with much larger basis sets than previously possible. We present calculations for 15NH-15NH collisions in a magnetic field. Our results support the conclusion of the previous study that the evaporative cooling of rotationally ground 15NH molecules in a magnetic trap has a prospect of success.
Optimization of a charge-state analyzer for electron cyclotron resonance ion source beams
Authors: Saminathan S. , Beijers J. P. M. , Kremers H. R. , Mironov V. , Mulder J. , Brandenburg S.
Published: July 2012

A detailed experimental and simulation study of the extraction of a 24 keV He+ beam from an ECR ion source and the subsequent beam transport through an analyzing magnet is presented. We find that such a slow ion beam is very sensitive to space-charge forces, but also that the neutralization of the beam's space charge by secondary electrons is virtually complete for beam currents up to at least 0.5 mA. The beam emittance directly behind the extraction system is 65 π mm mrad and is determined by the fact that the ion beam is extracted in the strong magnetic fringe field of the ion source. The relatively large emittance of the beam and its non-paraxiality lead, in combination with a relatively small magnet gap, to significant beam losses and a five-fold increase of the effective beam emittance during its transport through the analyzing magnet. The calculated beam profile and phase-space distributions in the image plane of the analyzing magnet agree well with measurements. The kinematic and magnet aberrations have been studied using the calculated second-order transfer map of the analyzing magnet, with which we can reproduce the phase-space distributions of the ion beam behind the analyzing magnet. Using the transfer map and trajectory calculations we have worked out an aberration compensation scheme based on the addition of compensating hexapole components to the main dipole field by modifying the shape of the poles. The simulations predict that by compensating the kinematic and geometric aberrations in this way and enlarging the pole gap the overall beam transport efficiency can be increased from 16% to 45%.