bluuebunny/crossref_metadata_2025 huggingface dataset:
A Novel Zwitterionic Imidazolium‐Based Ionic Liquid Surfactant: 1‐Carboxymethyl‐3‐Dodecylimidazolium Inner Salt
Authors: Liu Xue‐feng , Dong Li‐li , Fang Yun
Published: March 2011

A novel zwitterionic imidazolium‐based ionic liquid (IL) surfactant, 1‐carboxymethyl‐3‐dodecylimidazolium inner salt, was synthesized. The molecule structure was confirmed by means of electrospray ionization mass spectrometry, 1H nuclear magnetic resonance and elemental analysis. The isoelectric point (pI) is 3.8 ± 0.1 at 35 ± 0.1 °C. The other important physicochemical parameters such as the critical micelle concentration (CMC), the surface tension at CMC (γCMC), the adsorption efficiency (pC20), the surface pressure at CMC (ΠCMC), the maximum surface excess (Γm), the minimum molecular cross‐sectional area (Amin), the value of CMC/C20 and the average number of aggregation (Nm) were determined by surface tension and steady‐state fluorescence probe methods, respectively.
Changes in Total Polar Compounds, Peroxide Value, Total Phenols and Antioxidant Activity of Various Oils Used in Deep Fat Frying
Authors: Karakaya Sibel , Şimşek Şebnem
Published: March 2011

In this study, the effect of deep fat frying on oil degradation, total phenols (TP) and total antioxidant activity (TAA) of hazelnut, corn, soybean and olive oils were investigated. Oil degradation and oxidation were monitored by measuring the total polar compounds (TPC) and the peroxide value (PV). The amount of TPC in corn, soybean and olive oils increased significantly with the time increment (p < 0.05). The PV of the oils did not exceed the maximum acceptable limit of 10 mequiv O2/kg after 125 min frying except for hazelnut oil (10.64 mequiv O2/kg). Deep‐fat frying did not cause any significant change in the TP of corn oil, soybean oil and olive oil (p < 0.05). A significant decrease in the antioxidant activity was observed after 50 min frying using hazelnut oil and corn oil (p < 0.05). However, the antioxidant activity of soybean oil and olive oil significantly decreased after 75 and 25 min frying, respectively.
Debt to Society: Asset Poverty and Prisoner Reentry
Authors: Martin Lori Latrice
Published: March 2011

Every year, millions of people exit American jails and prisons and attempt to reintegrate into society. Ex-offenders face many obstacles during the transition. Scholars contend that securing employment is central to a successful transition. A job that allows an ex-offender to earn an income above the poverty line is especially significant, recent studies have shown. Consequently, many prisoner reentry initiatives are focused on expanding employment opportunities for ex-offenders. However, the almost exclusive emphasis on employment as the measurement of economic well-being is short-sighted because it ignores the importance of financial education and asset ownership. Prisoner reentry programs should include an emphasis on financial education in addition to an emphasis on employment as a means of reducing recidivism rates and improving the economic well-being of the ex-offenders and receiving communities. The paper concludes with a discussion of policy implications.
The developing oligodendrocyte: key cellular target in brain injury in the premature infant
Authors: Volpe Joseph J. , Kinney Hannah C. , Jensen Frances E. , Rosenberg Paul A.
Published: March 2011

Brain injury in the premature infant, a problem of enormous importance, is associated with a high risk of neurodevelopmental disability. The major type of injury involves cerebral white matter and the principal cellular target is the developing oligodendrocyte. The specific phase of the oligodendroglial lineage affected has been defined from study of both human brain and experimental models. This premyelinating cell (pre‐OL) is vulnerable because of a series of maturation‐dependent events. The pathogenesis of pre‐OL injury relates to operation of two upstream mechanisms, hypoxia‐ischemia and systemic infection/inflammation, both of which are common occurrences in premature infants. The focus of this review and of our research over the past 15–20 years has been the cellular and molecular bases for the maturation‐dependent vulnerability of the pre‐OL to the action of the two upstream mechanisms. Three downstream mechanisms have been identified, i.e., microglial activation, excitotoxicity and free radical attack. The work in both experimental models and human brain has identified a remarkable confluence of maturation‐dependent factors that render the pre‐OL so exquisitely vulnerable to these downstream mechanisms. Most importantly, elucidation of these factors has led to delineation of a series of potential therapeutic interventions, which in experimental models show marked protective properties. The critical next step, i.e., clinical trials in the living infant, is now on the horizon.
Sedimentary Cladocera as indicators of past water-level changes in shallow northern lakes
Authors: Nevalainen Liisa , Sarmaja-Korjonen Kaarina , Luoto Tomi P.
Published: March 2011

The usability of subfossil Cladocera assemblages in reconstructing long-term changes in lake level was examined by testing the relationship between Cladocera-based planktonic/littoral (P/L) ratio and water-level inference model in a surface-sediment dataset and in a 2000-yr sediment record in Finland. The relationships between measured and inferred water levels and P/L ratios were significant in the dataset, implying that littoral taxa are primarily deposited in shallow littoral areas, while planktonic cladocerans accumulate abundantly mainly in deepwater locations. The 2000-yr water-level reconstructions based on the water-level inference model and P/L ratio corresponded closely with each other and with a previously available midge-inferred water-level reconstruction from the same core, showing a period of lower water level around AD 300–1000 and suggesting that the methods are valid for paleolimnological and -climatological use.
Scanning for Genomic Regions Subject to Selective Sweeps Using SNP-MaP Strategy
Authors: Deng Libin , Tang Xiaoli , Chen Wei , Lin Jiari , Lai Zhiqing , Liu Zuoqi , Zhang Dake
Published: March 2011

Population genomic approaches, which take advantages of high-throughput genotyping, are powerful yet costly methods to scan for selective sweeps. DNA-pooling strategies have been widely used for association studies because it is a cost-effective alternative to large-scale individual genotyping. Here, we performed an SNP-MaP (single nucleotide polymorphism microarrays and pooling) analysis using samples from Eurasia to evaluate the efficiency of pooling strategy in genome-wide scans for selection. By conducting simulations of allelotype data, we first demonstrated that the boxplot with average heterozygosity (HET) is a promising method to detect strong selective sweeps with a moderate level of pooling error. Based on this, we used a sliding window analysis of HET to detect the large contiguous regions (LCRs) putatively under selective sweeps from Eurasia datasets. This survey identified 63 LCRs in a European population. These signals were further supported by the integrated haplotype score (iHS) test using HapMap II data. We also confirmed the European-specific signatures of positive selection from several previously identified genes (KEL, TRPV5, TRPV6, EPHB6). In summary, our results not only revealed the high credibility of SNP-MaP strategy in scanning for selective sweeps, but also provided an insight into the population differentiation.
SNPTransformer: A Lightweight Toolkit for Genome-Wide Association Studies
Authors: Dong Changzheng
Published: March 2011

High-throughput genotyping chips have produced huge datasets for genome-wide association studies (GWAS) that have contributed greatly to discovering susceptibility genes for complex diseases. There are two strategies for performing data analysis for GWAS. One strategy is to use open-source or commercial packages that are designed for GWAS. The other is to take advantage of classic genetic programs with specific functions, such as linkage disequilibrium mapping, haplotype inference and transmission disequilibrium tests. However, most classic programs that are available are not suitable for analyzing chip data directly and require custom-made input, which results in the inconvenience of converting raw genotyping files into various data formats. We developed a powerful, user-friendly, lightweight program named SNPTransformer for GWAS that includes five major modules (Transformer, Operator, Previewer, Coder and Simulator). The toolkit not only works for transforming the genotyping files into ten input formats for use with classic genetics packages, but also carries out useful functions such as relational operations on IDs, previewing data files, recoding data formats and simulating marker files, among other functions. It bridges upstream raw genotyping data with downstream genetic programs, and can act as an in-hand toolkit for human geneticists, especially for non-programmers. SNPTransformer is freely available at http://snptransformer.sourceforge.net.
REFLEXIBLE REGULAR MAPS WITH NO NON-TRIVIAL EXPONENTS FROM RESIDUAL FINITENESS
Authors: ŠIRÁŇ JOZEF , STANEKOVÁ ĽUBICA , OLEJÁR MARIÁN
Published: March 2011

Regular maps, that is, graph embeddings with the ‘highest level’ of orientation-preserving symmetry, can be identified with two-generator presentations of groups G of the form 〈x, y; xm = y2 = (xy)n = … = 1〉; the parameters m and n are the valence and the covalence of the map, respectively. The element j ∈ Zm* is an exponent of such a map if the assignments x ↦ xj and y ↦ y extend to an automorphism of G. The element −1 is an exponent if and only if the map is reflexible, that is, isomorphic to its mirror image. Non-trivial exponents, j ≠ ±1, induce automorphisms of the underlying graph, which are not map automorphisms but can nevertheless be considered as ‘external symmetries’ of the map. In this paper we show with the help of residual finiteness of triangle groups that for any given m, n≥3 such that 1/m + 1/n ≤ 1/2, there exist infinitely many finite, reflexible and regular maps of valence m and covalence n with no non-trivial exponent.
Prediction of grape production by grapevine cultivar Godello in north-west Spain
Authors: FERNÁNDEZ-GONZÁLEZ M. , ESCUREDO O. , RODRÍGUEZ-RAJO F. J. , AIRA M. J. , JATO V.
Published: March 2011

Advance knowledge of potential grape production is of great value for harvest and post-harvest planning, in that it enables the winery to estimate requirements in terms of crop insurance and grape-picking workforce, and to optimize post-harvest processes.

An aerobiological and phenological study of the Godello grape variety was carried out at a vineyard belonging to the Ribeiro Designation of Origin (Ourense, Spain) from 2004 to 2009. Aerobiological data were obtained using a Lanzoni VPPS-2000 volumetric trap placed inside the vineyard, while phenological observations were conducted on 20 selected vines, using the Biologische Bundesanstalt, Bundessortenamt and chemical industry(BBCH) standardized scale. Pollen production per anther and per grapevine was studied during the flowering stage, and airborneVitispollen counts were recorded. This information was used to develop a model for predicting local grape production. The equation obtained accounted for 0·99 of harvest variability, thus enabling accurate prediction of grape production 1-month in advance.
Particle acceleration in plasmas by perpendicularly propagating waves
Authors: BINGHAM R. , CAIRNS R. A. , MENDONÇA J. T.
Published: March 2011

The acceleration of particles to high energy by relativistic plasma waves
has received a great deal of attention lately. Most of the particle-acceleration
schemes using relativistic plasma waves rely either on intense terawatt or petawatt
lasers or on electron beams as the driver of the acceleration wave. These laboratory
experiments have attained accelerating fields as high as 1 GeV cm−1 with the
electrons being accelerated to about 100 MeV in millimetre distances. In space and
astrophysical plasmas, relativistic plasma waves can also be important for acceleration.
A process that is common to both laboratory and space plasmas is the surfatron
concept, which operates as a wave acceleration mechanism in a magnetized
plasma. In this paper, we present test-particle results for the surfatron process.
On resistive magnetohydrodynamic equilibria of an axisymmetric toroidal plasma with flow
Authors: THROUMOULOPOULOS G. N. , TASSO H.
Published: March 2011

It is shown that the magnetohydrodynamic (MHD) equilibrium
states of an axisymmetric toroidal plasma with finite resistivity and flows
parallel to the magnetic field are governed by a second-order partial differential
equation for the poloidal magnetic flux function ψ coupled with a
Bernoulli-type equation for the plasma density (which are identical in form to the
corresponding ideal MHD equilibrium equations) along with the relation
Δ*ψ = Vcσ (here Δ* is the Grad–Schlüter–Shafranov operator, σ is the
conductivity and Vc is the constant toroidal-loop voltage divided by 2π). In
particular, for incompressible flows, the above-mentioned partial differential
equation becomes elliptic and decouples from the Bernoulli equation [H. Tasso
and G. N. Throumoulopoulos, Phys. Plasma5, 2378 (1998)]. For a conductivity
of the form σ = σ(R, ψ) (where R is the distance from the axis of symmetry),
several classes of analytic equilibria with incompressible flows can be
constructed having qualitatively plausible σ profiles, i.e. profiles with σ taking
a maximum value close to the magnetic axis and a minimum value on the
plasma surface. For σ = σ(ψ), consideration of the relation Δ*ψ = Vc σ(ψ) in the
vicinity of the magnetic axis leads then to a proof of the non-existence of either
compressible or incompressible equilibria. This result can be extended to the
more general case of non-parallel flows lying within the magnetic surfaces.
Spelling, phonology and etymology in Hittite historical linguistics
Authors: Weeden Mark
Published: March 2011

This is a review article on Alwin Kloekhorst,Etymological Dictionary of the Hittite Inherited Lexicon(Leiden Indo-European Etymological Dictionary Series 5. Leiden and Boston: Brill, 2008. $199. ISBN 978 90 04 16092 7). The article addresses issues arising from Kloekhorst's depiction of Hittite cuneiform spelling conventions in the context of the wider cuneiform world (Mesopotamia and Northern Syria). In particular the representation of a glottal stop in Hittite and relevant cuneiform writing is addressed. The second part of the article addresses further individual graphic and lexical issues arising throughout the etymological dictionary.
The peripheral protectionist backlash in theFirst Globalization: Spain (1870-1913)
Authors: Sabaté Marcela , Fillat Carmen , Gracia Ana Belén
Published: March 2011

This paper studies the role played by different trade barriers (transport costs, customs and currency) in the evolution of Spanish imports during theFirst Globalization(1870-1913). Through the estimation of several gravity equations with panel data analysis, we obtain the elasticities of imports to each barrier, which allows us to combine them into a singlead valoremmeasure of barriers to trade (which we call thetrade costs tariff equivalent). More interestingly, the contribution of the barriers to the profile of thetariff equivalent, as well as the assignment of an active role to the peseta exchange rate as a barrier, illustrates the existence of a protectionist backlash against the sustained decline in transport costs in the period 1870-1913.
Solute behaviour and export rates in neotropical montane catchments under different land-uses
Authors: Bücker Amelie , Crespo Patricio , Frede Hans-Georg , Breuer Lutz
Published: March 2011

To improve our knowledge of the influence of land-use on solute behaviour and export rates in neotropical montane catchments we investigated total organic carbon (TOC), Ca, Mg, Na, K, NO3and SO4concentrations during April 2007–May 2008 at different flow conditions and over time in six forested and pasture-dominated headwaters (0.7–76 km2) in Ecuador. NO3and SO4concentrations decreased during the study period, with a continual decrease in NO3and an abrupt decrease in February 2008 for SO4. We attribute this to changing weather regimes connected to a weakening La Niña event. Stream Na concentration decreased in all catchments, and Mg and Ca concentration decreased in all but the forested catchments during storm flow. Under all land-uses TOC increased at high flows. The differences in solute behaviour during storm flow might be attributed to largely shallow subsurface and surface flow paths in pasture streams on the one hand, and a predominant origin of storm flow from the organic layer in the forested streams on the other hand. Nutrient export rates in the forested streams were comparable to the values found in literature for tropical streams. They amounted to 6–8 kg ha−1y−1for Ca, 7–8 kg ha−1y−1for K, 4–5 kg ha−1y−1for Mg, 11–14 kg ha−1y−1for Na, 19–22 kg ha−1y−1for NO3(i.e. 4.3–5.0 kg ha−1y−1NO3-N) and 17 kg ha−1y−1for SO4. Our data contradict the assumption that nutrient export increases with the loss of forest cover. For NO3we observed a positive correlation of export value and percentage forest cover.
Responses of plant functional types to environmental gradients in the south-west Ethiopian highlands
Authors: Wana Desalegn , Beierkuhnlein Carl
Published: March 2011

Plant functional types across environmental gradients can be considered as a powerful proxy that reveals vegetation–environment relationships. The objectives of this study were to investigate the response in the relative abundance of plant functional types along altitudinal gradients and to examine the relationship of plant functional types to environmental variables. The study was conducted in the Gughe-Amaro Mountains, in the south-west Ethiopian highlands. We established 74 plots with an area of 400 m2(20 × 20 m) each along altitudinal ranges between 1000 and 3000 m asl. Data on site environmental conditions and on the abundance of plant functional types were analysed using the constrained linear ordination technique (RDA) in order to identify the relationships between plant functional types and environmental variables. Altitude, soil organic carbon, soil sand fraction and surface stone cover were significantly related to the relative abundance of plant functional types across the gradient. Tussocks and thorns/spines were abundant in lower altitudinal ranges in response to herbivory and drought while rhizomes and rosettes were abundant at higher altitudes in response to the cold. Generally our results show that topographic attributes (altitude and slope) as well as soil organic carbon play an important role in differentiating the relative abundance of plant functional types in the investigated gradient. Thus, considering specific plant functional types would provide a better understanding of the ecological patterns of vegetation and their response to environmental gradients in tropical regions of Africa prone to drought.
Effects of altitude and vegetation on small-mammal distribution in the Urucum Mountains, western Brazil
Authors: Caceres Nilton Carlos , Godoi Maurício Neves , Hannibal Wellington , Ferreira Vanda Lúcia
Published: March 2011

We conducted a study on small-mammal composition, abundance and diversity across altitudinal and vegetational gradients in the Urucum Mountains (from 150 to 1000 m asl) in western Brazil, a complex biogeographic region. Small mammals were collected in 31 sampling units distributed along altitudinal and vegetational gradients (forest and grassland), totalling 18 112 trap-nights for pitfall and 3500 trap-nights for live-trap. Community variation among sampling units was assessed by randomization tests, setting altitude, vegetation, locality and time as factors, and using presence/absence data. Correlation and logistic regression analyses were run for species and diversity along gradients of altitude and vegetation, according to abundance and presence/absence data. Nineteen species (seven marsupial and 12 rodent) and 355 individuals were recorded. The species composition of small mammals differed according to altitude, vegetation type, locality and time. Species diversity varied significantly according to altitude. Species were influenced solely by altitude or vegetation, or by both vegetation and altitude concomitantly. The small-mammal community was divided in two groups according to biogeographic affinities. The grassland group is capable of invading forest habitats. The results are discussed in light of current hypotheses that attempt to explain community variation along altitudinal gradients around the world.
‘God's earth will be sacred’: Religion, Theology, and the Open Space Movement in Victorian England
Authors: BAIGENT ELIZABETH
Published: March 2011

The Victorian open space movement is accounted for variously by nostalgia, progress, and a changed conception of national identity, but explanatory factors are generally understood in secular ways which take little account of the pervasive influence of contemporary Christianity. These explanations overlap with discussions of nineteenth-century leisure which stress its links with secularisation. Christianity however was a significant motivation for some open space campaigners whose theology explainedhownature was to uplift those who experienced it. This paper considers the Commons Preservation Society, founded in 1865; the preservation of Epping Forest for recreation between 1865 and 1880; and the forest's management in the 1880s and 1890s. It argues that although histories of the Commons Preservation Society and the Epping Forest campaign describe them in secular, rational terms, many prominent campaigners were motivated by religion, in the sense of orthodox Christianity. Practical religion significantly affected the development of mass recreation for the poor in the forest. Explanations of the open space movement which ignore religion thus seem inadequate.
Herman on Moral Literacy
Authors: Engstrom Stephen
Published: March 2011

In her recent book, Barbara Herman explores a range of topics commonly associated with virtue ethics; her focus, however, is not so much on virtue as on normal moral competence and the basic moral capacity underpinning it. To explicate this competence, Herman introduces the idea of moral literacy, arguing that it reveals Kantian ethical thought to be better able than Humean views to account for our readiness to hold persons responsible even for conduct reflecting character flaws that stem from deficiencies in their upbringing. Examination of Herman's account raises a question, however, about how intimately moral literacy is related to the basic moral capacity.
Embracing Kant's Formalism
Authors: Herman Barbara
Published: March 2011

In response to critical discussions of my book,Moral Literacy, by Stephen Engstrom, Sally Sedgwick and Andrews Reath, I offer a defence of Kant's formalism that is not only friendly to my claims for the moral theory's sensitivity to a wide range of moral phenomena and practices at the ground level, but also consistent with Kant's high rationalist ambitions.
Any Answers? Questions for Suppliers
Authors: Percik David
Published: March 2011

Because the focus of most of the themed articles in this issue of LIM is vendor relations from the point of view of the customer, it seemed sensible to allow the legal publishers to present their own views of relations with their customers to the readership, via a short survey carried out by BIALL's Legal Information Group.
Vendor Relations: Tales from a Vendee
Authors: Kitchen Julie
Published: March 2011

Julie Kitchen is a law librarian with many years experience of working for law firms large and small. In this article she provides an account of her personal experiences with vendors over the years and offers some suggestions for helping to improve the relationship.
You're Hired! Practical Tips and Techniques for the Confident Interview
Authors: Gray Keri
Published: March 2011

Keri Gray gave a practical presentation at the June 2010 BIALL Conference covering practical tips and techniques to make the most of yourself before and during an interview.
Feminist International Relations
Authors: Prügl Elisabeth
Published: March 2011

Feminist international relations is situated uneasily within a subfield of political science, on the one hand, and within an interdisciplinary literature on globalization, on the other. Emerging in the 1990s from a critique of the realist and rationalist IR canon, feminist IR research has diversified considerably, including different lines of theoretical and empirical inquiry and drawing on a range of methods. Different emphases emerge in three fields – feminist security studies, feminist international political economy, and feminist work on international governance.
Conformal antenna array for ultra-wideband direction-of-arrival estimation
Authors: Liberal Iñigo , Caratelli Diego , Yarovoy Alexander
Published: March 2011

The design and full-wave analysis of an antenna system for ultra-wideband radio direction finding applications is presented. The elliptical dipole antenna is selected as antenna element due to its robust circuital and radiation properties. The influence of the conformal deformation on the antenna performance has been studied in details. A suitable radome is designed to enhance the antenna front-to-back radiation ratio, as well as to increase the environmental durability of the structure. The considered antennas are optimized for their adoption in two different sub-arrays covering the [250, 950] MHz and [0.9, 3.3] GHz frequency bands, respectively. A uniform circular array (UCA) with five elements is used for the array topology. The full-wave analysis of the whole array structure is carried out in order to evaluate the coupling between the antenna elements. In particular, a novel calibration technique is developed in order to compensate for the mutual coupling between the array elements, possible variations in the antenna characteristics, and the effects of the array bearing structure. The performance of the designed array in terms of direction-of-arrival estimation is thoroughly analyzed and discussed.
Reinforcement of cancer immunotherapy by adoptive transfer of cblb‐deficient CD8+ T cells combined with a DC vaccine
Authors: Lutz‐Nicoladoni Christina , Wallner Stephanie , Stoitzner Patrizia , Pircher Magdalena , Gruber Thomas , Wolf Anna Maria , Gastl Günther , Penninger Josef M , Baier Gottfried , Wolf Dominik
Published: March 2011

The success of cancer immunotherapy is limited by potent endogenous immune‐evasion mechanisms, which are at least in part mediated by transforming growth factor‐β (TGF‐β). The E3 ubiquitin ligase Cbl‐b is a key regulator of T cell activation and is established to regulate TGF‐β sensitivity. cblb‐deficient animals reject tumors via CD8+ T cells, which make Cbl‐b an ideal target for improvement of adoptive T‐cell transfer (ATC) therapy. In this study, we show that cblb‐deficient CD8+ T cells are hyper‐responsive to T‐cell receptor (TCR)/CD28‐stimulation and are in part protected against the negative cues induced by TGF‐β in vitro. Notably, adoptive transfer of polyclonal, non‐TCR transgenic cblb‐deficient CD8+ T cells is not sufficient to reject B16‐ova or EG7 tumors in vivo. Thus, cblb‐deficient ATC requires proper in vivo re‐activation by a dendritic cell (DC) vaccine. In strict contrast to ATC monotherapy, this approach delayed tumor outgrowth and significantly increased survival rates, which is paralleled by increased CD8+ T‐cells infiltration to the tumor site and enrichment of ova‐specific and interferon‐γ (IFN‐γ)‐secreting CD8+ T cell in the draining lymph node (LN). Moreover, CD8+ T cells from cblb‐deficient mice vaccinated with the DC vaccine show increased cytolytic activity in vivo. In summary, our data using cblb‐deficient polyclonal, non‐TCR‐transgenic adoptively transferred CD8+ T cells into immuno‐competent non‐lymphodepleted recipients suggest that targeting Cbl‐b might serve as a novel ‘adjuvant approach’, suitable to augment the effectiveness of established anti‐cancer immunotherapies.
Protistan microbial observatory in the Cariaco Basin, Caribbean. II. Habitat specialization
Authors: Orsi William , Edgcomb Virginia , Jeon Sunok , Leslin Chesley , Bunge John , Taylor Gordon T , Varela Ramon , Epstein Slava
Published: March 2011

This is the second paper in a series of three that investigates eukaryotic microbial diversity and taxon distribution in the Cariaco Basin, Venezuela, the ocean's largest anoxic marine basin. Here, we use phylogenetic information, multivariate community analyses and statistical richness predictions to test whether protists exhibit habitat specialization within defined geochemical layers of the water column. We also analyze spatio-temporal distributions of protists across two seasons and two geographic sites within the basin. Non-metric multidimensional scaling indicates that these two basin sites are inhabited by distinct protistan assemblages, an observation that is supported by the minimal overlap in observed and predicted richness of sampled sites. A comparison of parametric richness estimations indicates that protistan communities in closely spaced—but geochemically different—habitats are very dissimilar, and may share as few as 5% of total operational taxonomic units (OTUs). This is supported by a canonical correspondence analysis, indicating that the empirically observed OTUs are organized along opposing gradients in oxidants and reductants. Our phylogenetic analyses identify many new clades at species to class levels, some of which appear restricted to specific layers of the water column and have a significantly nonrandom distribution. These findings suggest many pelagic protists are restricted to specific habitats, and likely diversify, at least in part due to separation by geochemical barriers.
Modeling scanning probe microscope lateral dynamics using the probe–surface interaction signal
Authors: Okorafor M. , Clayton G. M.
Published: March 2011

In this paper, a novel scanning probe microscope (SPM) modeling technique is presented. The novelty of this technique is that it exploits the SPM’s probe–surface interaction measurement capabilities [e.g., the topography signal in atomic force microscopy (AFM)] to determine the SPM’s lateral positioning dynamics. SPM operation speed is limited due to mechanical vibrations induced by movement of the SPM nanopositioner. In order to facilitate high-speed SPM operation, the dynamics of the SPM can be modeled and used to design feedforward and feedback controllers that reduce nanopositioner vibrations. The proposed technique seeks to develop a transfer function model of the SPM dynamics using only the SPM probe–surface interaction signal obtained while scanning a calibration sample. The technique is presented in the context of an AFM example, errors associated with the method are analyzed, and the method is experimentally verified using a commercial AFM. Experimental modeling results show that the method is capable of modeling the dynamics of SPM systems.
The role of radiation transport in the thermal response of semitransparent materials to localized laser heating
Authors: Colvin Jeffrey , Shestakov Aleksei , Stölken James , Vignes Ryan
Published: March 2011

Lasers are widely used to modify the internal structure of semitransparent materials for a wide variety of applications, including waveguide fabrication and laser glass damage healing. The gray diffusion approximation used in past models to describe radiation cooling is not adequate for these materials, particularly near the heated surface layer. In this paper we describe a computational model based upon solving the radiation transport equation in 1D by the Pn method with ∼500 photon energy bands, and by multi-group radiation diffusion in 2D with fourteen photon energy bands. The model accounts for the temperature-dependent absorption of infrared laser light and subsequent redistribution of the deposited heat by both radiation and conductive transport. We present representative results for fused silica irradiated with 2–12 W of 4.6 or 10.6 µm laser light for 5–10 s pulse durations in a 1 mm spot, which is small compared to the diameter and thickness of the silica slab. We show that, unlike the case for bulk heating, in localized infrared laser heating radiation transport plays only a very small role in the thermal response of silica.
Acceptor-related emissions in indium-doped ZnO nanorods
Authors: Liu Chao , He Haiping , Sun Luwei , Yang Qian , Ye Zhizhen , Chen Lanlan
Published: March 2011

Temperature-dependent photoluminescence (PL) properties of indium-doped ZnO nanorods grown by vapor transport method are investigated. At low temperatures, two peaks at 3.294 and 3.221 eV are observed. With the temperature increasing, these peaks shift to 3.315 and 3.238 eV, respectively. This is the characteristic of the transformation from donor–acceptor pair recombination to free electron-to-neutral acceptor (eA0) transition. Two acceptors are identified with energy levels of ∼120 and ∼200 meV (labeled A1 and A2). The nanorods show yellow emission around 2.1 eV at 8 K, which blueshifts to 2.3 eV at room temperature. From the thermal quenching analysis, it is suggested that the acceptor involved in the yellow emission is the same as A2. A defect level close to A1 is also observed in the PL-excitation spectrum. A schematic model is proposed to interpret the transitions responsible for the emissions.
Suppressing harmonic vibrations of a miniature cryogenic cooler using an adaptive tunable vibration absorber based on magneto-rheological elastomers
Authors: Kim Y.-K. , Koo J. H. , Kim K.-S. , Kim S. H.
Published: March 2011

This paper presents dynamic performances of an adaptive tunable vibration absorber (TVA) designed to suppress the main harmonic disturbance of a miniature linear cryogenic cooler, which is being used in space applications such as an observation satellite. The adaptive TVA employs a magneto-rheological elastomer (MRE) for a variable stiffness element. This study first investigates the shear modulus change of MRE samples with respect to the magnetic flux density, which varies through the alignment of particle chains. The MRE with the maximal shear modulus change is mounted for the TVA on a prototype cooler, which emulates the characteristics of a miniature cryogenic cooler. Using the test setup, a series of vibration tests are performed to evaluate the performance and efficacy of the MRE TVA and its re-tuning ability. The experimental results show that the MRE TVA is able to robustly suppress the vibration of the cooler even when the frequency of resonant vibration is changed up to 87% from its initial frequency.
Characterization of acoustically engineered polymer nanocomposite metamaterials using x-ray microcomputed tomography
Authors: Mitri F. G. , Garzon F. H. , Sinha D. N.
Published: March 2011

We demonstrate the fabrication of acoustically engineered diamond nanoparticles-based metamaterials and their internal microstructure characterization using x-ray microcomputed tomography (XμCT). The state-of-the-art technique based on the radiation force of ultrasound standing (or stationary) waves in a rectangular chamber is utilized to pattern clusters of 5-nm-diameter diamond nanoparticles in parallel planes within a three-dimensional (3D) matrix of epoxy before solidification. Gradually, the periodic pattern becomes permanent with full cure of the epoxy matrix so as to form a 3D metamaterial structure. We also show that the periodicity of the pattern can be changed by selecting a different ultrasound frequency. Furthermore, XμCT is used as a quality control tool to map the internal structure and characterize each metamaterial. The ultimate application is to use the results as a base for the development of finite-element models which take into account all the structural features to study the various metamaterial (optical, acoustical, thermal, etc.) functional properties.
Effects of gate-last and gate-first process on deep submicron inversion-mode InGaAs n-channel metal-oxide-semiconductor field effect transistors
Authors: Gu J. J. , Wu Y. Q. , Ye P. D.
Published: March 2011

Recently, encouraging progress has been made on surface-channel inversion-mode In-rich InGaAs NMOSFETs with superior drive current, high transconductance and minuscule gate leakage, using atomic layer deposited (ALD) high-k dielectrics. Although gate-last process is favorable for high-k/III–V integration, high-speed logic devices require a self-aligned gate-first process for reducing the parasitic resistance and overlap capacitance. On the other hand, a gate-first process usually requires higher thermal budget and may degrade the III–V device performance. In this paper, we systematically investigate the thermal budget of gate-last and gate-first process for deep-submicron InGaAs MOSFETs. We conclude that the thermal instability of (NH4)2S as the pretreatment before ALD gate dielectric formation leads to the potential failure of enhancement-mode operation and deteriorates interface quality in the gate-first process. We thus report on the detailed study of scaling metrics of deep-submicron self-aligned InGaAs MOSFET without sulfur passivation, featuring optimized threshold voltage and negligible off-state degradation.
Photopolymerizable glasses incorporating high refractive index species and ionic liquid: A comparative study
Authors: Velasco A. V. , Hernández-Garay M. P. , Calvo M. L. , Cheben P. , del Monte F.
Published: March 2011

Three different holographic photomaterials belonging to the class of photopolymerizable glasses have been synthesized using sol-gel techniques, and characterized with the purpose of a comparative study. Their behavior is analyzed in terms of achieved refractive index modulation, dark diffusion mechanism, diffraction efficiency and optical quality; in order to determine their suitability for different holographic applications.
An approach for generating trajectory-based dynamics which conserves the canonical distribution in the phase space formulation of quantum mechanics. I. Theories
Authors: Liu Jian , Miller William H.
Published: March 2011

We have reformulated and generalized our recent work [J. Liu and W. H. Miller, J. Chem. Phys. 126, 234110 (2007)] into an approach for generating a family of trajectory-based dynamics methods in the phase space formulation of quantum mechanics. The approach (equilibrium Liouville dynamics) is in the spirit of Liouville's theorem in classical mechanics. The trajectory-based dynamics is able to conserve the quantum canonical distribution for the thermal equilibrium system and approaches classical dynamics in the classical (ℏ → 0), high temperature (β → 0), and harmonic limits. Equilibrium Liouville dynamics provides the framework for the development of novel theoretical/computational tools for studying quantum dynamical effects in large/complex molecular systems.
Effects of tip induced carrier density in local tunnel spectra of graphene
Authors: Choudhary Shyam K. , Gupta Anjan K.
Published: March 2011

We report on tip induced carrier density changes in local tunnel spectra of single layer graphene (SLG) with backgate using room-temperature scanning tunneling microscopy (STM) and spectroscopy. The SLG samples, prepared by exfoliation method and verified by Raman spectra, show atomically resolved honeycomb lattice. Local tunnel spectra show two minima with the two moving in opposite directions along the bias axis. One minimum shows nearly a square-root dependence, and the other shows a linear dependence on gate voltage. We understand these features as arising from the STM tip induced and bias voltage dependent change in carrier density in SLG.
Rapid thermal annealing of size-controlled Si nanocrystals: Dependence of interface defect density on thermal budget
Authors: Hiller Daniel , Goetze Silvana , Zacharias Margit
Published: March 2011

Photoluminescence properties of size-controlled Si nanocrystals (NCs) formed by various annealings have been studied in detail. The thermal treatments involve rapid thermal annealing (RTA, 10 to 180 s) as well as conventional tube furnace annealing (1h) at 1100 °C. Whereas the photoluminescence (PL) peak positions and the TEM images indicate only minor changes in NC size, the PL intensity varies over more than two orders of magnitude. A correlation between the total thermal budget applied by the different annealing treatments and the PL intensity is demonstrated. In addition, the PL improvement of interface defect passivation by post-annealing in H2 ambient is investigated. RTA with H2 passivation is not able to achieve the PL intensity and NC interface quality of conventionally annealed and passivated samples. The combination of these results with our previous electron spin resonance studies allows to estimate the interface defect densities. Tube furnace annealed samples after H2 treatment have less than 2% defective NCs. In contrast, more than 95% defective NCs are assumed for a 180 s RTA.
Dynamical mean-field theory from a quantum chemical perspective
Authors: Zgid Dominika , Chan Garnet Kin-Lic
Published: March 2011

We investigate the dynamical mean-field theory (DMFT) from a quantum chemical perspective. Dynamical mean-field theory offers a formalism to extend quantum chemical methods for finite systems to infinite periodic problems within a local correlation approximation. In addition, quantum chemical techniques can be used to construct new ab initio Hamiltonians and impurity solvers for DMFT. Here, we explore some ways in which these things may be achieved. First, we present an informal overview of dynamical mean-field theory to connect to quantum chemical language. Next, we describe an implementation of dynamical mean-field theory where we start from an ab initio Hartree–Fock Hamiltonian that avoids double counting issues present in many applications of DMFT. We then explore the use of the configuration interaction hierarchy in DMFT as an approximate solver for the impurity problem. We also investigate some numerical issues of convergence within DMFT. Our studies are carried out in the context of the cubic hydrogen model, a simple but challenging test for correlation methods. Finally, we finish with some conclusions for future directions.
Correlations between low temperature thermoluminescence and oxygen vacancies in ZnO crystals
Authors: Wang Y. , Yang B. , Can N. , Townsend P. D.
Published: March 2011

Low temperature thermoluminescence spectra of zinc oxide single crystals are presented in this paper. The signals can be interpreted in terms of annealing and inter-conversion of oxygen vacancy sites. Minor differences between signals from different suppliers suggest such vacancies are perturbed by association with complexes and impurities. Significant changes of bulk signals result from high dose surface ion implantation. This is an important demonstration of extremely long range effects resulting from ion implantation into the surface layer. Such extensive changes have rarely been considered, or experimentally sought. It is therefore fortunate that for ZnO the thermoluminescence signals offer a sensitive probe to monitor this phenomenon.
Ultrafast electrocyclic ring opening of 7-dehydrocholesterol in solution: The influence of solvent on excited state dynamics
Authors: Tang Kuo-Chun , Rury Aaron , Orozco Michael B. , Egendorf Joshua , Spears Kenneth G. , Sension Roseanne J.
Published: March 2011

Broadband UV-visible femtosecond transient absorption spectroscopy and steady-state integrated fluorescence were used to study the excited state dynamics of 7-dehydrocholesterol (provitamin D3, DHC) in solution following excitation at 266 nm. The major results from these experiments are: (1) The excited state absorption spectrum is broad and structureless spanning the visible from 400 to 800 nm. (2) The state responsible for the excited state absorption is the initially excited state. Fluorescence from this state has a quantum yield of ∼2.5 × 10−4 in room temperature solution. (3) The decay of the excited state absorption is biexponential, with a fast component of ∼0.4–0.65 ps and a slow component 1.0–1.8 ps depending on the solvent. The spectral profiles of the two components are similar, with the fast component redshifted with respect to the slow component. The relative amplitudes of the fast and slow components are influenced by the solvent. These data are discussed in the context of sequential and parallel models for the excited state internal conversion from the optically excited 11B state. Although both models are possible, the more likely explanation is fast bifurcation between two excited state geometries leading to parallel decay channels. The relative yield of each conformation is dependent on details of the potential energy surface. Models for the temperature dependence of the excited state decay yield an intrinsic activation barrier of ∼2 kJ/mol for internal conversion and ring opening. This model for the excited state behavior of DHC suggests new experiments to further understand the photochemistry and perhaps control the excited state pathways with optical pulse shaping.
Optical cell for combinatorial in situ Raman spectroscopic measurements of hydrogen storage materials at high pressures and temperatures
Authors: Hattrick-Simpers Jason R. , Hurst Wilbur S. , Srinivasan Sesha S. , Maslar James E.
Published: March 2011

An optical cell is described for high-throughput backscattering Raman spectroscopic measurements of hydrogen storage materials at pressures up to 10 MPa and temperatures up to 823 K. High throughput is obtained by employing a 60 mm diameter × 9 mm thick sapphire window, with a corresponding 50 mm diameter unobstructed optical aperture. To reproducibly seal this relatively large window to the cell body at elevated temperatures and pressures, a gold o-ring is employed. The sample holder-to-window distance is adjustable, making this cell design compatible with optical measurement systems incorporating lenses of significantly different focal lengths, e.g., microscope objectives and single element lenses. For combinatorial investigations, up to 19 individual powder samples can be loaded into the optical cell at one time. This cell design is also compatible with thin-film samples. To demonstrate the capabilities of the cell, in situ measurements of the Ca(BH4)2 and nano-LiBH4–LiNH2–MgH2 hydrogen storage systems at elevated temperatures and pressures are reported.
Isotope effects in ice Ih: A path-integral simulation
Authors: Herrero Carlos P. , Ramírez Rafael
Published: March 2011

Ice Ih has been studied by path-integral molecular dynamics simulations, using the effective q-TIP4P/F potential model for flexible water. This has allowed us to analyze finite-temperature quantum effects in this solid phase from 25 to 300 K at ambient pressure. Among these effects we find a negative thermal expansion of ice at low temperatures, which does not appear in classical molecular dynamics simulations. The compressibility derived from volume fluctuations gives results in line with experimental data. We have analyzed isotope effects in ice Ih by considering normal, heavy, and tritiated water. In particular, we studied the effect of changing the isotopic mass of hydrogen on the kinetic energy and atomic delocalization in the crystal as well as on structural properties such as interatomic distances and molar volume. For D2O ice Ih at 100 K we obtained a decrease in molar volume and intramolecular O–H distance of 0.6% and 0.4%, respectively, as compared to H2O ice.