bluuebunny/crossref_metadata_2025 huggingface dataset:
The Political Culture of Sugar Tariffs: Immigration, Race, and Empire, 1898–1930
Authors: Merleaux April
Published: July 2012

This article contends that the chronology of popular and legislative movements for restrictive tariffs and immigration exclusion in the United States ran parallel courses between 1898 and the 1930. Those who spoke for and against such policies did so using the rhetoric of race, labor, and empire. The article analyzes the career of Nevada Senator Francis G. Newlands in order to show how the sugar industry and Asian immigration were intrinsic to debates over imperial policy between 1898 and the First World War. The article then describes policy changes during the First World War. The war set the stage for renewed debates over immigration and the sugar trade in the 1920s as the newly formed Tariff Commission attempted to grapple with an oversupplied world sugar market. Their work ultimately reinforced the old associations among race, labor, and trade policy and did little to improve the global sugar crisis.
Gender and Class: Women's Working Lives in a Dormitory Labor Regime in China
Authors: Ngai Pun
Published: July 2012

The thirty years since Women on the Line has witnessed great achievement in the literature of gender and work both in the West and Global South. There was a booming literature since the 1970s and 1980s in the fields of sociology, anthropology, women studies, and cultural studies—most of them excellent works that touch upon sophisticated debates on the interplay between gender and work, production and reproduction, dominance, and resistance in an increasingly globalized context.
History, Villagers, and the Social Scientists: Wrestling with the Past in the Present
Authors: McDonald Tracy
Published: July 2012

What is the relationship between the historical Soviet countryside and the post-Soviet present both for the scholars who study them and for the population that inhabits them? Together Margaret Paxson, Solovyovo: The Story of Memory in a Russian Village; Jessica Allina-Pisano, The Post-Soviet Potemkin Village: Politics and Property Rights in the Black Earth; and Douglas Rogers, The Old Faith and the Russian Land: A Historical Ethnography of Ethics in the Urals create a rich, nuanced portrait of contemporary rural life in parts of the former Soviet Union. When one reads the three books together, one finds evidence of interesting continuity alongside dynamism and change that varies depending on the region and on the questions that motivated the researcher. The three works ask in varied ways how individuals in post-Soviet society perceive their world and attempt to live in it. The three studies extend far and wide across the territory of the former Soviet Union: Solovyovo, three hundred miles north of Moscow; the Black Earth, more than four hundred miles to the south; and Sepych, about one thousand miles to the east.
Interests of a Legal Nature Justifying Intervention before the ICJ
Authors: BONAFÉ BEATRICE I.
Published: July 2012

According to Article 62 of the ICJ Statute, a third state can be granted permission to intervene before the Court provided ‘that it has an interest of a legal nature which may be affected by the decision in the case’. The interest of a legal nature is a crucial requirement under Article 62 and the scope of intervention largely depends on the definition of such a requirement. In light of the recent case law of the Court, the author explores the different types of legal interest that could justify permitting a third state to intervene before the ICJ.
Evaluation of the vaccination efficacy against H5N1 in domestic poultry in the Red River Delta in Vietnam
Authors: DESVAUX S. , GROSBOIS V. , PHAM T. T. H. , DAO D. T. , NGUYEN T. D. , FENWICK S. , ROGER F. , ELLIS T. , PEYRE M.
Published: July 2012

The domestic poultry population in Vietnam has been vaccinated against highly pathogenic avian influenza (HPAI) H5N1 since 2005. Since then, outbreaks have continued to occur without a clear understanding of the mechanisms involved. The general objective of this study was to understand the epidemiology of the disease in the context of vaccination and to draw some conclusions about vaccination efficacy in the domestic poultry population of the Red River Delta area. Five cross-sectional surveys to measure the serological and virological prevalence in vaccinated and unvaccinated poultry were performed from the end of 2008 to June 2010. The global seroprevalence was 24% (95% confidence interval 19·9–28·2). Determinants of vaccine immunogenicity were identified separately in chickens and ducks as well as determinants of the seroconversion in unvaccinated birds. The results highlight the difficulties in maintaining good flock immunity in poultry populations using inactivated vaccine in the field with two vaccination rounds per year, and in preventing circulation of virus in co-existing unvaccinated poultry.
Urban rejection of the vernacular: The SVS undone
Authors: Dodsworth Robin , Kohn Mary
Published: July 2012

In Raleigh, North Carolina, a Southern U.S. city, five decades of in-migration of technology-sector workers from outside the South has resulted in large-scale contact between the local Southern dialect and non-Southern dialects. This paper investigates the speed and magnitude of the reversal of the Southern Vowel Shift (SVS) with respect to the five front vowels, using Trudgill's (1998) model of dialect contact as a framework. The data consist of conversational interviews with 59 white-collar Raleigh natives representing three generations, the first generation having reached adulthood before large-scale contact. Acoustic analysis shows that all vowels shift away from their Southern variants across apparent time. The leveling of SVS variants begins within the first generation to grow up after large-scale contact began, and contrary to predictions, this generation does not show wide inter- or intraspeaker variability. Previous studies of dialect contact and new dialect formation suggest that leveling of regional dialect features and the establishment of stable linguistic norms occurs more quickly when children have regular contact with one another. Dialect contact in Raleigh has occurred primarily within the middle and upper classes, the members of which are densely connected by virtue of schools and heavy economic segregation in neighborhood residence.
Smoke stimulates germination in two divergent Gondwanan species (Hibbertiapancheri and Scaevola montana) endemic to the biodiversity hotspot of New Caledonia
Authors: Wulff Adrien S. , Turner Shane R. , Fogliani Bruno , L'Huillier Laurent
Published: July 2012

Due to shared geological history and proximity, the flora of New Caledonia is closely linked to other Gondwanan land fragments such as Australia and New Zealand. Many predominant Australian groups are well represented within the New Caledonian flora, including the genera Hibbertia (23 species) and Scaevola (10 species). Previous studies have found that these two genera in particular have a marked positive germination response to smoke products, although all previous studies have centred on Australian species from fire-prone environments. In this present study, we test the hypothesis that two New Caledonian species of Hibbertia and Scaevola are smoke responsive even though the climate and ecological drivers in New Caledonia are in many respects fundamentally different from those of most of Australia. Preliminary results showed that germination of Hibbertia pancheri was significantly accelerated in response to smoke water while germination in Scaevola montana was also significantly enhanced. To the best of our knowledge, this is the first time that these trends have been illustrated for any New Caledonian species and these results will enhance restoration efforts of ultramafic scrublands impacted by mining activities in New Caledonia.
The impact of adding front-of-package sodium content labels to grocery products: an experimental study
Authors: Goodman Samantha , Hammond David , Hanning Rhona , Sheeshka Judy
Published: August 2012

Objective

Canadians consume approximately twice the daily Adequate Intake of sodium. The present study examined the efficacy of four types of front-of-package (FOP) sodium labels at influencing consumers’ selection of products lowv. high in sodium.

Design

Participants were randomly assigned to one of five experimental conditions: (i) control condition with no FOP label; (ii) basic numeric FOP label; (iii) numeric FOP label with ‘high’ and ‘low’ sodium content descriptors; (iv) detailed Traffic Light (TL) label with colour coding, content descriptors and numeric information; and (v) simple TL label with no numeric information. Participants were shown pairs of grocery products that varied in sodium content and told they could choose a free sample. Selection of the low-sodiumv. the high-sodium product was the primary behavioural outcome, in addition to ratings of effectiveness, understanding, liking and believability.

Setting

Waterloo, Ontario, Canada.

Subjects

Adults (n430) aged ≥18 years, recruited from community settings.

Results

Participants in the three FOP conditions with ‘high/low’ sodium content descriptors were significantly more likely to choose the lower-sodium product compared with the control group. The detailed TL label was ranked most effective at helping participants select low-sodium products, and was rated significantly higher than other formats in liking, understanding and believability. Product selection did not differ significantly across sociodemographic groups.

Conclusions

FOP labels that include content descriptors may be more effective in helping consumers to select lower-sodium products. TL labels, which incorporate content descriptors and colour coding, should be considered for future FOP labelling initiatives.
Two-Photon Imaging of Microbial Immunity in Living Tissues
Authors: Herz Jasmin , Zinselmeyer Bernd H. , McGavern Dorian B.
Published: July 2012

The immune system is highly evolved and can respond to infection throughout the body. Pathogen-specific immune cells are usually generated in secondary lymphoid tissues (e.g., spleen, lymph nodes) and then migrate to sites of infection where their functionality is shaped by the local milieu. Because immune cells are so heavily influenced by the infected tissue in which they reside, it is important that their interactions and dynamics be studied in vivo. Two-photon microscopy is a powerful approach to study host-immune interactions in living tissues, and recent technical advances in the field have enabled researchers to capture movies of immune cells and infectious agents operating in real time. These studies have shed light on pathogen entry and spread through intact tissues as well as the mechanisms by which innate and adaptive immune cells participate in thwarting infections. This review focuses on how two-photon microscopy can be used to study tissue-specific immune responses in vivo, and how this approach has advanced our understanding of host-immune interactions following infection.
Deconvolution of Calcium Fluorescent Indicator Signal from AFM Cantilever Reflection
Authors: Lopez-Ayon G. Monserratt , Oliver David J. , Grutter Peter H. , Komarova Svetlana V.
Published: July 2012

Atomic force microscopy (AFM) can be combined with fluorescence microscopy to measure the changes in intracellular calcium levels (indicated by fluorescence of Ca2+ sensitive dye fluo-4) in response to mechanical stimulation performed by AFM. Mechanical stimulation using AFM is associated with cantilever movement, which may interfere with the fluorescence signal. The motion of the AFM cantilever with respect to the sample resulted in changes of the reflection of light back to the sample and a subsequent variation in the fluorescence intensity, which was not related to changes in intracellular Ca2+ levels. When global Ca2+ responses to a single stimulation were assessed, the interference of reflected light with the fluorescent signal was minimal. However, in experiments where local repetitive stimulations were performed, reflection artifacts, correlated with cantilever motion, represented a significant component of the fluorescent signal. We developed a protocol to correct the fluorescence traces for reflection artifacts, as well as photobleaching. An added benefit of our method is that the cantilever reflection in the fluorescence recordings can be used for precise temporal correlation of the AFM and fluorescence measurements.
Combined Major and Trace Element LA-ICP-MS Analysis of Compositional Variations in Simple Solid Solutions through Cross Correlation with an EPMA-Characterized Working Standard
Authors: Zellmer Georg F. , Dulski Peter , Iizuka Yoshiyuki
Published: July 2012

Determining correlated major and trace element zoning profiles is an important goal in modern microanalysis and is critical to some geospeedometric applications. We show that a precise determination of relative variations in major element compositions of simple solid solutions is possible by LA-ICPMS, and that low accuracy (analytical bias) can be corrected for through cross correlation with electron problem microanalyzer (EPMA)-characterized working standards. Further, the relative uncertainties on binary or quasibinary solid solution endmember proportions are always lower than the relative uncertainties on the ratio of the principle substituting elements by at least a factor of 2. In calcic plagioclase, for example, the relative uncertainty on XAn is a factor of (1 − XAn) smaller than the relative uncertainty on Ca/Na. Using a well-characterized, concentrically zoned bytownite crystal as an example, we compare reproducibilities of FE-EPMA and W-EPMA analyses with 2 μm beam diameter and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) with 16 μm beam diameter. While the accuracy of LA-ICP-MS analyses is low (analytical bias), the precision of LA-ICP-MS analyses is slightly higher than that of FE-EPMA data and comparable to that of the W-EPMA data. EPMA-corrected LA-ICP-MS data can thus be used to characterize major oxide compositional variations and potential covariations with trace elements within individual crystals.
Evaluation of Ethiopian chickpea (Cicer arietinumL.) germplasm accessions for symbio-agronomic performance
Authors: Keneni Gemechu , Bekele Endashaw , Assefa Fassil , Imtiaz Muhammad , Debele Tolessa , Dagne Kifle , Getu Emana
Published: July 2012

Chickpea (Cicer arietinumL.) is an economically and ecologically important food legume crop. Ethiopia has a large collection of chickpea germplasm accessions; but, it has not been extensively characterized for desirable sources of agronomic and symbiotic significance for use in breeding programs. A study was conducted at two locations (Ambo and Ginchi) in 2009/2010 to characterize and evaluate Ethiopian chickpea germplasm accessions for symbiotic and agronomic performance. One hundred and thirty-nine germplasm accessions were evaluated with 16 other genotypes including non-nodulating reference checks. Differences among genotypes, locations and genotype by location interaction effects were significant for a number of characters. A number of accessions better performing over the improved genotypes were identified for both symbiotic and agronomic characters. The amount of fixed nitrogen ranged from 13 to 49% in foliage, 30 to 44% in grain and 28 to 40% in total above-ground biomass. Grain yield performance varied from 31 to 70 g per 5 plants and seed size ranged from 82 to 288 g per 1000 seeds. For both symbiotic and agronomic characters, landraces were found to be overwhelmingly superior to introduced genotypes, except for seed size, where the best genotypes were all from exotic sources. The result indicated that Ethiopian chickpea landraces have better genetic potential for improving a number of symbiotic and agronomic characters over the varieties currently in use. Selection of best individuals within and among the accessions would be expected to be effective.
Jesus Q. Politician: Religious Rhetoric in the United States, Australia, and Canada
Authors: Gin Willie
Published: July 2012

Sociologist Peter Berger once said that if India is the most religious country and Sweden the least, then the United States is a nation of Indians ruled by Swedes. In terms of use of religious rhetoric by politicians, however, the United States actually comes closer to being a nation of Indians ruled by Indians, while Australia a nation of Swedes ruled by “Swindians,” and Canada a nation of “Swindians” ruled by Swedes. This article provides evidence for these claims and assesses theories as to what causes greater use of religious rhetoric by politicians. Size of the religious population and the rights revolution are not decisive in determining whether politicians heavily use religious rhetoric. The article argues that the politicization of religion is related to coalition-building incentives with Catholics.
The Culture of Obedience and the Politics of Stealth: Mormon Mobilization Against ERA and Same-Sex Marriage
Authors: Gordon Elizabeth Ellen , Gillespie William L.
Published: July 2012

Political mobilization by the Church of Jesus Christ of Latter-Day Saints against ratification of the Equal Rights Amendment (ERA) was more widespread and important than most studies of the episode have acknowledged. Several decades later, the Church is again organized and active in opposing legal recognition of same-sex marriage. In this article, we explore why and how the Latter-Day Saints mobilized on these two issues. We argue that their mobilization can be understood through classic social movement theory, even though the Church is not an economic-based interest group. Furthermore, the Mormons' approach in fighting the ERA — drawing on centralized authority, tapping into established volunteer and communications networks, effectively channeling money and personnel to where they are most needed, and engaging in stealth politics (obscuring the centralized nature of apparently spontaneous action) — is echoed in the fight against same-sex marriage, even though the times and technology have somewhat changed the mobilization dynamic.
Frequency–wavenumber velocity spectra, Taylor's hypothesis, and length scales in a natural gravel bed river
Authors: MacMahan Jamie , Reniers Ad , Ashley Will , Thornton Ed
Published: August 2012

Macroscale turbulent coherent flow structures in a natural fast‐flowing river were examined with a combination of a novel 2 MHz Acoustic Doppler Beam (ADB) and a Maximum Likelihood Estimator (MLE) to characterize the streamwise horizontal length scales and persistence of coherent flow structures by measuring the frequency (f)‐streamwise‐wavenumber (ks) energy density velocity spectrum, E(f, ks), for the first time in natural rivers. The ADB was deployed under a range of Froude numbers (0.1–0.6) at high Reynolds numbers (∼106) based on depth and velocity conditions within a gravel bed reach of the Kootenai River, Idaho. The MLE employed on the ADB data increased our ability to describe river motions with relatively long (>10 m) length scales in ∼1 m water depths. The E(f, ks) spectra fell along a ridge described by V = f/ks, where Vis the mean velocity over depth, consistent with Taylor’s hypothesis. New, consistent length scale measures are defined based on averaged wavelengths of the low‐frequencyE(f, ks) and coherence spectra. Energetic (∼50% of the total spectral energy), low‐frequency (f < 0.05 Hz) streamwise motions were found. Mean length scales,Lm, compared with the depth, h, are significantly larger than previously suggested for macroturbulence with Lm/h∼ 28–118. Although the energy appears as low‐pass white noise, it is streamwise coherent along the length of the array. In fast flows with velocities > 1 m/s,Lmwere found to be significantly longer than their corresponding coherence lengths, suggesting that the turbulent structures evolve rapidly under these conditions. This is attributed to the stretching and concomitant deformation of preexisting macroturbulent motions by the ubiquitous bathymetry‐induced spatial flow accelerations present in a natural gravel bed river.
Cabled ocean observatories in Sea of Oman and Arabian Sea
Authors: DiMarco Steven F. , Wang Zhankun , Jochens Ann , Stoessel Marion , Howard Matthew K. , Belabbassi Leila , Ingle Stephanie , du Vall Ken
Published: July 2012

An ocean observatory—consisting of a real‐time, cabled array in the Sea of Oman and an internally recording, autonomous mooring array recently upgraded to a cabled array in the northern Arabian Sea—celebrated more than 2500 days of continuous operation in July 2012. The observatory, which measures a range of properties, such as water current velocities, temperature, salinity, pressure, dissolved oxygen, and turbidity, is part of the Lighthouse Ocean Research Initiative (LORI) project [du Vall et al., 2011], which was designed as a pilot project and installed in 2005 in the region off Abu Bakara (Figures 1a and 1b). The initial goal of the project was to prove that an in situ, cabled ocean observatory can return high‐quality scientific data on a real‐time basis over longer time periods than conventional moored systems. That same year, an autonomous array was deployed off Ras al Hadd and on Murray Ridge in the Arabian Sea (Figure 1a).
Scholars program applications deadline
Authors: Showstack Randy
Published: July 2012

The New York Academy of Sciences, in partnership with the U.S. Department of State and a consortium of nearly 40 women's colleges, has launched the NeXXt Scholars Program for the 2012ndash;2013 academic year. The program aims to “engage, connect, and advance young women from countries with predominantly Muslim populations and young American women to pursue undergraduate degrees in science, technology, engineering, and math (STEM) fields,” according to the academy. The academy will provide partnership, mentorship, and networking support for these scholars with a selected STEM mentor fellow. The deadline for applications is 10 August. For more information, see http://www.nyas.org/NexxtScholars.
Paul A. Witherspoon (1919–2012)
Authors: Freeze R. Allan , Javandel Iraj , Neuman Shlomo P.
Published: July 2012

The hydrologic community lost one of its most charismatic leaders with the death of Paul Witherspoon on 10 February 2012, in Berkeley, Calif. He passed away from complications brought on by his long battle with Parkinson's disease. He was 93. Paul was a dynamic and influential research leader in hydrogeology for more than 50 years. Working from his base at the University of California, Berkeley (UC Berkeley), and later from the Lawrence Berkeley National Laboratory (LBNL), he made significant contributions to the understanding of the flow of fluids in porous media and fractured rock, and he applied his findings to a diverse set of societally important issues, including the development of geothermal energy, use of underground gas storage, and siting and design of nuclear waste disposal facilities. In all these spheres of interest he emphasized the need to marry theoretical studies and field testing. He was especially passionate about the need for large‐scale, in situ, underground experiments to guide and corroborate the predictions of theoretically based numerical models.
Seasonal algae plays critical role in North Pacific carbon uptake
Authors: Schultz Colin
Published: July 2012

The role of the North Pacific Ocean as a net carbon sink may prove to be more precarious than previously thought as researchers work to isolate the contributions of biological and physical processes to air‐sea gas exchange. Scientists have long known that physical processes, such as the seasonally changing solubility of carbon dioxide in seawater, combine with a biological pump driven by seasonal shifts in phytoplankton growth to control the carbon dioxide flux in the region. A dearth of on‐site evidence regarding biological pump function, however, has prevented researchers from assessing the relative importance of either mechanism to known carbon uptake rates. Using data collected during four cruises from 2003 to 2008, Juranek et al. determined the strength of the biological pump, finding that for the northern Pacific Ocean it was strong enough to counteract solubility‐induced outgassing in summer, turning a net source region into a carbon sink.
New corrections for skylight estimates
Authors: Bhattacharya Atreyee
Published: July 2012

Skylight, also known as diffuse solar radiation, accounts for about 16% of the total solar radiation reaching the Earth's surface; the percentage varies depending on external factors, such as the angle of the Sun with respect to the zenith and the composition of the atmosphere as well as on properties of the surface, such as albedo and tilt. Of all the factors, the composition of the atmosphere changes most frequently, primarily due to changing cloud cover and the amount and type of aerosols in the atmosphere in a given region. At present, numerical methods used to calibrate measuring devices such as shadow rings, which are bands held parallel to the sunbeam to block direct sunlight and measure the diffuse light reaching a sensor, assume an unchanging atmosphere. Such assumptions do not account for local conditions and hence can introduce large errors in skylight measurements.
Local spectral variability and the origin of the Martian crustal magnetic field
Authors: Lewis Kevin W. , Simons Frederik J.
Published: August 2012

The crustal remanent magnetic field of Mars remains enigmatic in many respects. Its heterogeneous surface distribution points to a complex history of formation and modification, and has been resistant to attempts at identifying magnetic paleopoles and constraining the geologic origin of crustal sources. We use a multitaper technique to quantify the spatial diversity of the field via the localized magnetic power spectrum, which allows us to isolate more weakly magnetized regions and characterize them spectrally for the first time. We find clear geographical differences in spectral properties and parameterize them in terms of source strengths and equivalent‐layer decorrelation depths. These depths to the base of the magnetic layer in our model correlate with independent crustal‐thickness estimates. The correspondence indicates that a significant fraction of the martian crustal column may contribute to the observed field, as would be consistent with an intrusive magmatic origin. We identify several anomalous regions, and propose geophysical mechanisms for generating their spectral signatures.
Spatial dependence of banded chorus intensity near the magnetic equator
Authors: Haque N. , Inan U. S. , Bell T. F. , Pickett J. S.
Published: August 2012

Data from 12 different Cluster orbits containing banded chorus emissions, with observations from 22 different events spread across the four Cluster spacecraft, are used to show the spatial dependence of banded chorus intensity near the magnetic equator under conditions of moderate magnetic disturbance (Kp≤ 5). The intensities for upper band (UB) and lower band (LB) chorus were manually determined from frequency‐time spectrograms generated from WBD data. Out of the 22 events, 5 of the spacecraft observations showed a complete absence of chorus emissions within 0.5° of the magnetic equator. The intensity,I, of the chorus emissions generally increased exponentially with distance, z, away from the magnetic equator according to the relation I = Ioeaz, where α is the spatial growth factor. The exponential distribution of α provides a new boundary condition for consideration in current and future chorus generation models.
Improved simulation of the terrestrial hydrological cycle in permafrost regions by the Community Land Model
Authors: Swenson S. C. , Lawrence D. M. , Lee Hanna
Published: July 2012

Plausible predictions of future climate require realistic representations of past and current climate. Simulations of the distribution of permafrost in the 21st century made with the Community Climate System Model (CCSM4) indicate that substantial decreases in permafrost extent can be expected, especially under high emissions scenarios. One of the implications of permafrost loss is the potential release of carbon from newly thawed soils into the atmosphere, thus raising its concentration of greenhouse gases and amplifying the initial warming trend. However, the biogeochemical cycle simulated by CCSM4 presents significant biases in carbon fluxes such as gross primary production, net primary production, and vegetation carbon storage in permafrost regions. The biases in the carbon cycle simulated \by CCSM4 are in part due to excessively dry soils in permafrost regions. In this study, we show that the CCSM4 dry soil bias results from the model's formulation of soil hydraulic permeability when soil ice is present. The calculation of the hydraulic properties of frozen soils is first modified by replacing their dependence on total water content with liquid water content only. Then an ice impedance function having a power‐law form is incorporated. When the parameterization of the hydraulic properties of frozen soil is corrected, the model simulates significantly higher moisture contents in near‐surface soils in permafrost regions, especially during spring. This result is validated qualitatively by comparing soil moisture profiles to descriptions based on field studies, and quantitatively by comparing simulated hydrographs of two large Siberian rivers to observed hydrographs. After the dry soil bias is reduced, the vegetation productivity simulated by the model is improved, which is manifested in leaf area indices that at some locations are twice as large as in the original model.
Note: Cryogenic microstripline-on-Kapton microwave interconnects
Authors: Harris A. I. , Sieth M. , Lau J. M. , Church S. E. , Samoska L. A. , Cleary K.
Published: August 2012

Simple broadband microwave interconnects are needed for increasing the size of focal plane heterodyne radiometer arrays. We have measured loss and crosstalk for arrays of microstrip transmission lines in flex circuit technology at 297 and 77 K, finding good performance to at least 20 GHz. The dielectric constant of Kapton substrates changes very little from 297 to 77 K, and the electrical loss drops. The small cross-sectional area of metal in a printed circuit structure yields overall thermal conductivities similar to stainless steel coaxial cable. Operationally, the main performance tradeoffs are between crosstalk and thermal conductivity. We tested a patterned ground plane to reduce heat flux.
Electromagnetic fluctuation spectrum associated with the drift Alfvén-cyclotron instability
Authors: Rha Kicheol , Ryu Chang-Mo , Yoon Peter H.
Published: July 2012

The present paper investigates the electromagnetic fluctuation spectrum associated with the drift Alfvén-cyclotron instability by means of a two-dimensional particle-in-cell simulation, which may be plausibly associated with a current disruption event. The current disruption event shows localized high-amplitude electromagnetic fluctuations. In recent theories, these fluctuation characteristics are shown to correspond to the drift Alfvén-cyclotron instability. A simulation is carried out to clarify this instability. The simulation shows that the drift Alfvén-cyclotron instabilities are excited in two frequency regimes, a relatively low frequency mode propagating in a quasi-perpendicular direction while the second high-frequency branch propagating in a predominantly parallel propagation direction, consistent with observations as well as with a recent theory.
An instrument for fast acquisition of fluorescence decay curves at picosecond resolution designed for “double kinetics” experiments: Application to fluorescence resonance excitation energy transfer study of protein folding
Authors: Ishay Eldad Ben , Hazan Gershon , Rahamim Gil , Amir Dan , Haas Elisha
Published: August 2012

The information obtained by studying fluorescence decay of labeled biopolymers is a major resource for understanding the dynamics of their conformations and interactions. The lifetime of the excited states of probes attached to macromolecules is in the nanosecond time regime, and hence, a series of snapshot decay curves of such probes might - in principle - yield details of fast changes of ensembles of labeled molecules down to sub-microsecond time resolution. Hence, a major current challenge is the development of instruments for the low noise detection of fluorescence decay curves within the shortest possible time intervals. Here, we report the development of an instrument, picosecond double kinetics apparatus, that enables recording of multiple fluorescence decay curves with picosecond excitation pulses over wide spectral range during microsecond data collection for each curve. The design is based on recording and averaging multiphoton pulses of fluorescence decay using a fast 13 GHz oscilloscope during microsecond time intervals at selected time points over the course of a chemical reaction or conformational transition. We tested this instrument in a double kinetics experiment using reference probes (N-acetyl-tryptophanamide). Very low stochastic noise level was attained, and reliable multi-parameter analysis such as derivation of distance distributions from time resolved FRET (fluorescence resonance excitation energy transfer) measurements was achieved. The advantage of the pulse recording and averaging approach used here relative to double kinetics methods based on the established time correlated single photon counting method, is that in the pulse recording approach, averaging of substantially fewer kinetic experiments is sufficient for obtaining the data. This results in a major reduction in the consumption of labeled samples, which in many cases, enables the performance of important experiments that were not previously feasible.
Versatile cold atom target apparatus
Authors: Götz Simone , Höltkemeier Bastian , Hofmann Christoph S. , Litsch Dominic , DePaola Brett D. , Weidemüller Matthias
Published: July 2012

We report on a compact and transportable apparatus that consists of a cold atomic target at the center of a high resolution recoil ion momentum spectrometer. Cold rubidium atoms serve as a target which can be operated in three different modes: in continuous mode, consisting of a cold atom beam generated by a two-dimensional magneto-optical trap, in normal mode in which the atoms from the beam are trapped in a three-dimensional magneto-optical trap (3D MOT), and in high density mode in which the 3D MOT is operated in dark spontaneous optical trap configuration. The targets are characterized using photoionization.
Fluctuating hydrodynamics for multiscale modeling and simulation: Energy and heat transfer in molecular fluids
Authors: Shang Barry Z. , Voulgarakis Nikolaos K. , Chu Jhih-Wei
Published: July 2012

This work illustrates that fluctuating hydrodynamics (FHD) simulations can be used to capture the thermodynamic and hydrodynamic responses of molecular fluids at the nanoscale, including those associated with energy and heat transfer. Using all-atom molecular dynamics (MD) trajectories as the reference data, the atomistic coordinates of each snapshot are mapped onto mass, momentum, and energy density fields on Eulerian grids to generate a corresponding field trajectory. The molecular length-scale associated with finite molecule size is explicitly imposed during this coarse-graining by requiring that the variances of density fields scale inversely with the grid volume. From the fluctuations of field variables, the response functions and transport coefficients encoded in the all-atom MD trajectory are computed. By using the extracted fluid properties in FHD simulations, we show that the fluctuations and relaxation of hydrodynamic fields quantitatively match with those observed in the reference all-atom MD trajectory, hence establishing compatibility between the atomistic and field representations. We also show that inclusion of energy transfer in the FHD equations can more accurately capture the thermodynamic and hydrodynamic responses of molecular fluids. The results indicate that the proposed MD-to-FHD mapping with explicit consideration of finite molecule size provides a robust framework for coarse-graining the solution phase of complex molecular systems.
Free energy landscapes for the thermodynamic understanding of adsorption-induced deformations and structural transitions in porous materials
Authors: Bousquet D. , Coudert F.-X. , Boutin A.
Published: July 2012

Soft porous crystals are flexible metal-organic frameworks that respond to physical stimuli such as temperature, pressure, and gas adsorption by large changes in their structure and unit cell volume. While they have attracted a lot of interest, molecular simulation methods that directly couple adsorption and large structural deformations in an efficient manner are still lacking. We propose here a new Monte Carlo simulation method based on non-Boltzmann sampling in (guest loading, volume) space using the Wang–Landau algorithm, and show that it can be used to fully characterize the adsorption properties and the material's response to adsorption at thermodynamic equilibrium. We showcase this new method on a simple model of the MIL-53 family of breathing materials, demonstrating its potential and contrasting it with the pitfalls of direct, Boltzmann simulations. We furthermore propose an explanation for the hysteretic nature of adsorption in terms of free energy barriers between the two metastable host phases.
Novel synchronization technique for two parallel connected sparkgap switches
Authors: Kumar Rohit , Mitra S. , Patel A. , Dwivedi Rajesh , Kolge T. , Sharma Ranjeet Archana , Chakravarthy D. P.
Published: August 2012

In this article a novel way of synchronizing two parallel connected sparkgap switches with accuracies of 1–5 ns for high frequency pulsed power applications is described. The circuit design of a synchronized sparkgap switch circuit is discussed. The circuit uses a combination of one master sparkgap and a set of inductor and capacitors to synchronize two sparkgaps and can be controlled via an IGBT switch. Critical issues for circuit design are presented together with analytical calculations and simulations. Experimental verification of the novel topology is carried out in a prototype experimental setup. Results showing nanosecond level of accuracy in synchronization are reported in this paper along with simulations and analysis.
Transverse-longitudinal correlations in electron guns
Authors: Harris J. R. , Lewellen J. W. , Poole B. R.
Published: July 2012

When a modulated beam is produced in a DC electron gun, the time-dependent space charge force and the time-independent focusing force produce a correlation between current, position along the beam, and the beam’s radius and divergence. This has implications for beam extraction and downstream beam transport. Here, we simulate an electrostatically-focused DC electron gun to study this correlation. Beam radius and divergence at the anode are found to be approximately linear functions of beam current, and the consequences for beam loss and extraction are considered.
A DFT study of reaction pathways of NH3 decomposition on InN (0001) surface
Authors: Walkosz Weronika , Zapol Peter , Stephenson G. Brian
Published: August 2012

Reaction pathways for complete decomposition of ammonia on the InN (0001) surface are investigated using first principles calculations. We show that while the initial NH3 decomposition on this surface can proceed by H dissociation, its further decomposition is most favorable by H transfer. The calculated low diffusion barriers for the decomposed species on the surface imply that the metal-organic chemical vapor deposition growth of InN is a reaction-limited process rather than diffusion-limited at low adsorbate coverage.
Thermal decomposition of a honeycomb-network sheet: A molecular dynamics simulation study
Authors: Paturej J. , Popova H. , Milchev A. , Vilgis T. A.
Published: August 2012

The thermal degradation of a graphene-like two-dimensional honeycomb membrane with bonds undergoing temperature-induced scission is studied by means of Molecular Dynamics simulation using Langevin thermostat. We demonstrate that at lower temperature the probability distribution of breaking bonds is highly peaked at the rim of the membrane sheet whereas at higher temperature bonds break at random everywhere in the hexagonal flake. The mean breakage time τ is found to decrease with the total number of network nodes N by a power law τ ∝ N−0.5 and reveals an Arrhenian dependence on temperature T. Scission times are themselves exponentially distributed. The fragmentation kinetics of the average number of clusters can be described by first-order chemical reactions between network nodes ni of different coordination. The distribution of fragments sizes evolves with time elapsed from initially a δ-function through a bimodal one into a single-peaked again at late times. Our simulation results are complemented by a set of 1st-order kinetic differential equations for ni which can be solved exactly and compared to data derived from the computer experiment, providing deeper insight into the thermolysis mechanism.
A numerical coarse-grained description of a binary alloy
Authors: Rickman J. M. , Delph T. J. , Webb E. B. , Fagan R.
Published: August 2012

We employ Monte Carlo simulation in the semi-grand canonical ensemble to obtain the coarse-grained free energy corresponding to an embedded-atom method description of a binary alloy. In particular, the Ginzburg-Landau free energy for a Cu–Ni alloy was determined from a tabulated histogram of the joint probability density of composition, energy, and volume. Using histogram reweighting techniques, the free energy is extrapolated to a range of points in parameter space from a small number of simulations. The results are interpreted by comparing the free energy with that corresponding to a regular solution model of an alloy. In addition, we obtain expressions for thermodynamic quantities in terms of the joint cumulants of the probability density at a given temperature and chemical potential difference. These expressions may then be likewise extrapolated to obtain the dependence of the composition on the temperature and the chemical potential difference over a wide range of parameter space.
Simultaneous surface plasmon resonance and x-ray absorption spectroscopy
Authors: Serrano A. , Rodríguez de la Fuente O. , Collado V. , Rubio-Zuazo J. , Monton C. , Castro G. R. , García M. A.
Published: August 2012

We present an experimental setup for the simultaneous measurement of surface plasmon resonance (SPR) and x-ray absorption spectroscopy (XAS) on metallic thin films at a synchrotron beamline. The system allows measuring in situ and in real time the effect of x-ray irradiation on the SPR curves to explore the interaction of x-rays with matter. It is also possible to record XAS spectra while exciting SPR in order to study changes in the films induced by the excitation of surface plasmons. Combined experiments recording simultaneously SPR and XAS curves while scanning different parameters can be also carried out. The relative variations in the SPR and XAS spectra that can be detected with this setup range from 10−3 to 10−5, depending on the particular experiment.
Practical system for the direct measurement of magneto-caloric effect by micro-thermocouples
Authors: Kamarád J. , Kaštil J. , Arnold Z.
Published: August 2012

A system for direct measurements of the magneto-caloric effect (MCE) exploits a rapid transport of a sample into or from magnetic field in permanent Halbach-type (1 T) or superconducting (4.7 T) magnets. Time dependence of induced changes of the sample temperature, ΔT(t), is detected directly by the differential Cu-Constantan-Cu micro-thermocouples with time steps of 300 ms. A sample placed inside an evacuated simple LN2 cryostat is either totally isolated (adiabatic conditions) or partly connected with the copper sample holder (non-adiabatic conditions). The last arrangement (a model of the Brayton cycle) is used to simulate an application of MCE in refrigeration techniques. The relations describing ΔT(t) that allow an analysis of MCE of the studied materials are based on the general cooling law. The effect of the first-order magnetic transition on MCE of selected sample is also demonstrated by non-standard ΔT(t) curves measured in the last mentioned experimental arrangements.
Micro-dent arrays fabricated by a novel net mask laser shock processing on the surface of LY2 aluminum alloy
Authors: Dai Feng-Ze , Lu Jin-Zhong , Zhang Yong-Kang , Luo Kai-Yu , Zhang Lei , Wang Qing-Wei , Ren Xu-Dong , Li Pin
Published: July 2012

A novel technology called net-mask laser shock processing (NMLSP) was introduced to fabricate micro-dent arrays on the surface of LY2 aluminum alloy. Experimental results showed that the as-fabricated micro-dents whose diameter and depth were about 230-250 μm and 9.3 μm, respectively, was closed to be circular although the original shape of the net mask was square. The height of upwarped area around micro-dent was about 4 μm. Moreover, the interference of neighboring surface shock waves would affect the topography of micro-dents. A dynamic analysis performed by ABAQUS/Explicit code exhibited that the dynamic formation process of micro-dents fabricated by NMLSP, and the simulation results were mostly consistent with experiment results.
Theoretical signal-to-noise ratio of a slotted surface coil for magnetic resonance imaging with experimental validation
Authors: Hidalgo S. S. , Solis S. E. , Ocegueda K. , Rodriguez A. O.
Published: August 2012

An analytical expression for the signal-to-noise ratio (SNR) of a slotted surface coil with an arbitrary number of slots was derived. This surface coil design is based on the magnetron tube. Theoretical signal-to-noise ratio results were compared to the signal-to-noise ratio of a single circular coil of similar dimensions. The slotted surface coil is able to produce a significant theoretical SNR improvement over the popular circular coil. To experimentally validate this coil design, a single channel slotted coil prototype with 8 vane-type slots was built and experimentally tested on 1.5 T magnetic resonance scanner using standard pulse sequences. Phantom images were acquired and used to compute the experimental signal-to-noise ratio. Signal-to-noise ratio theoretical predictions showed a very good agreement with the experimentally acquired signal-to-noise ratio data. This theoretical SNR model allows us to compute the coil performance in advance of experiments thus providing solid guidelines to specifically fabricate coils for particular applications. This theoretical approach should be useful in the development of this type of coil over a wide range of field strengths and applications.
Optimization of extreme ultraviolet photons emission and collection in mass-limited laser produced plasmas for lithography application
Authors: Sizyuk T. , Hassanein A.
Published: August 2012

The progress in development of commercial system for next generation EUV lithography requires, among other factors, significant improvement in EUV photon sources such as discharge produced plasma (DPP) and laser produced plasma (LPP) devices. There are still many uncertainties in determining the optimum device since there are many parameters for the suitable and efficient energy source and target configuration and size. Complex devices with trigger lasers in DPP or with pre-pulsing in LPP provide wide area for optimization in regards to conversion efficiency (CE) and components lifetime. We considered in our analysis a promising LPP source configuration using 10–30 μm tin droplet targets, and predicted conditions for the most efficient EUV radiation output and collection as well as calculating photons source location and size. We optimized several parameters of dual-beam lasers and their relationship to target size. We used our HEIGHTS comprehensive and integrated full 3D simulation package to study and optimize LPP processes with various target sizes to maximize the CE of the system.