bluuebunny/crossref_metadata_2025 huggingface dataset:
“WE DIDN'T CROSS THE COLOR LINE, THE COLOR LINE CROSSED US”
Authors: Sawyer Mark Q. , Paschel Tianna S.
Published: June 2008

We examine the interlinked migrations between the Dominican Republic and Haiti, between the Dominican Republic and the Commonwealth of Puerto Rico, and, finally, migrations from these three countries to the United States. The literature tends to draw stark differences between race and racism in the United States and the nonracial societies of Puerto Rico and the Dominican Republic. However, althoughBlacknessis a contextual category, through analyzing how “Black” migrants are racialized using these three contexts, we find that there is a simultaneously global and local derogation of “Blackness” that places Black migrants at the bottom of socioeconomic hierarchies. Further, these migrants remain largely outside of conceptions of the nation, and thus Blackness is constructed as a blend of racial phenotype and national origin, whereby native “Blacks” attempt to opt out of Blackness on account of their national identity. This dynamic is particularly true in the Caribbean whereBlanqueamiento, or Whitening, is made possible through a dialectical process in which a person's Whiteness, or at least his or her non-Blackness, is made possible by contrast to an “Other.” Consequently, we argue that immigration becomes a key site for national processes of racialization, the construction of racial identities, and the maintenance of and contestation over racial boundaries.
UNITY IN DIVERSITY?
Authors: Bloemraad Irene
Published: June 2008

This article considers how well the existing sociological literature on immigrant integration and assimilation responds to public fears over multiculturalism. The current backlash against multiculturalism rests on both its perceived negative effects for immigrants' socioeconomic integration and its failure to encourage civic and political cohesion. I offer a brief review of multiculturalism as political theory and public policy, demonstrating that multiculturalism addresses questions of citizenship and political incorporation, not socioeconomic integration. We have growing evidence that multiculturalism does not hurt immigrant citizenship or political integration, and might facilitate such processes. We know much less about the relationship between multiculturalism and socioeconomic outcomes. I discuss how sociologists have developed useful models of immigrants' socioeconomic assimilation but have paid scant attention to civic or political outcomes. They also have not adequately addressed the relationship between socioeconomic and political integration. We can, nonetheless, extrapolate from existing scholarship, and I outline two models of political integration that seem to emerge from the sociology of U.S. immigration: one of individual-level political assimilation, another of group-based political incorporation. I conclude by offering a number of hypotheses about the importance of “groupedness” for politics and the relationship between political action, multiculturalism, and socioeconomic integration.
KOREAN-LATINO RELATIONS IN LOS ANGELES AND NEW YORK
Authors: Min Pyong Gap
Published: June 2008

This paper examines Korean-Latino relations based on the results of my own research in New York City and review of other empirical studies conducted in New York and Los Angeles. Korean-Latino relations have been established mainly through the employment of Latino immigrants in Korean-owned stores. Since Korean immigrants' heavy dependence on very disadvantaged Latino workers involves labor exploitation, it has been a source of Korean-Latino conflicts. There have been many cases of picketing against Korean stores by Latino employees in both New York City and Los Angeles. But Korean-Latino business-related conflicts have been much less serious than Korean-Black business-related conflicts. Moreover, the relationships between Koreans and Latinos have some positive aspects. First, due to cultural similarities and mutual benefits derived from the employer-employee relationship, many Korean merchants maintain strong personal ties with Latino employees, informally helping them and often sponsoring their applications for green cards. Second, Korean ethnic organizations staffed by 1.5- and second-generation Koreans in Korean enclaves in Los Angeles and New York City have recently expanded their services to Latino immigrant workers and Latino children. In particular, the efforts of the Korean Immigrant Workers Advocates in Los Angeles to protect Latino workers from exploitation by Korean merchants have greatly contributed to establishing cultural, social, and organizational linkages between the two communities.
THE EFFECTS OF LABOR MARKET COMPETITION WITH IMMIGRANTS ON THE WAGES AND EMPLOYMENT OF NATIVES
Authors: Raphael Steven , Ronconi Lucas
Published: June 2008

This paper provides an overview of the current debate among economists pertaining to the effects of recent immigration on the earnings and employment of native-born workers. Since much of this debate revolves around methodological differences in research design, we devote much of our effort to discussing the various strategies that researchers have used to isolate immigrant competition effects, and attempt to clarify the strengths and weaknesses of each strategy. Our overall assessment is that the central tendency of the research evidence suggests that recent immigration has had only a modest effect on the labor market prospects of native-born Americans. Some potential hypotheses that may explain this lack of a large impact are capital accumulation and the imperfect substitutability between natives and immigrants.
FROM SHARED DEMOGRAPHIC CATEGORIES TO COMMON POLITICAL DESTINIES
Authors: Lee Taeku
Published: June 2008

Little controversy remains about the profound shifts in the demographic landscape of the United States since the mid-1960s. Far more controversial is whether this transformation will bring about a new politics of race. This paper argues that a key to settling this debate is a clearer specification of the “identity-to-politics” link: the nexus between a population defined by shared racial and ethnic labels and a collective group politics based on those definitions. The paper articulates some potential pitfalls in how this nexus is commonly specified in empirical research and proposes an approach that distinguishes five key processes that are typically lumped together in linking shared demographic categories to common political destinies: definition, identification, consciousness, venue selection, and choice. The paper describes an example of this approach (the case of ethnoracial classification and the empirical measurement of race) and concludes by discussing its potential utility and limitations.
A RETURN TO MORE BLATANT CLASS AND “RACE” BIAS IN U.S. IMMIGRATION POLICY?
Authors: Kim Nadia Y.
Published: June 2008

This essay explores the contradictions posed by states' efforts to exclude immigrants from south of the U.S. border on the grounds that they “burden” the economy, despite the same states' windfall revenue from the taxation of undocumented immigrants. Lawmakers' ongoing anti-immigrant sentiment yields a racialized contradiction in which mostly Mexican and Central American immigrants are derogated as economic burdens. In fact, they are unfairly taxed in addition to being indispensable to the U.S. economy. Based on these and other phenomena, such as racially coded preferences for higher-class immigrants and “antidiversity visas,” I contend that contemporary U.S. immigration policy has regressed toward more blatant class and “race” (albeit raciallycoded) discrimination.
A Role for Spatial and Nonspatial Working Memory Processes in Visual Search
Authors: Anderson Elaine J. , Mannan Sabira K. , Rees Geraint , Sumner Petroc , Kennard Christopher
Published: June 2008

Searching a cluttered visual scene for a specific item of interest can take several seconds to perform if the target item is difficult to discriminate from surrounding items. Whether working memory processes are utilized to guide the path of attentional selection during such searches remains under debate. Previous studies have found evidence to support a role for spatial working memory in inefficient search, but the role of nonspatial working memory remains unclear. Here, we directly compared the role of spatial and nonspatial working memory for both an efficient and inefficient search task. In Experiment 1, we used a dual-task paradigm to investigate the effect of performing visual search within the retention interval of a spatial working memory task. Importantly, by incorporating two working memory loads (low and high) we were able to make comparisons between dual-task conditions, rather than between dual-task and single-task conditions. This design allows any interference effects observed to be attributed to changes in memory load, rather than to nonspecific effects related to “dual-task” performance. We found that the efficiency of the inefficient search task declined as spatial memory load increased, but that the efficient search task remained efficient. These results suggest that spatial memory plays an important role in inefficient but not efficient search. In Experiment 2, participants performed the same visual search tasks within the retention interval of visually matched spatial and verbal working memory tasks. Critically, we found comparable dual-task interference between inefficient search and both the spatial and nonspatial working memory tasks, indicating that inefficient search recruits working memory processes common to both domains.
Does the Central Bottleneck Encompass Voluntary Selection of Hedonically Based Choices?
Authors: Pashler Harold , Harris Christine R. , Nuechterlein Keith H.
Published: June 2008

A large literature on multitasking bottlenecks suggests that people cannot generally make decisions or select responses in two different tasks at the same time. However, these tasks have all involved retrieving preinstructed responses, rather than spontaneously choosing actions based on anticipated hedonic consequences. To assess whether the same bottlenecks encompasses voluntary choices, a gambling decision was utilized as the second of two tasks in a psychological refractory period (PRP) design. Three decision-related factors were identified that affected latency of responding in the gambling task. All proved to be additive with stimulus-onset asynchrony (SOA) in dual-task blocks. The results indicate that making a choice to try to optimize outcomes is subject to the same processing bottleneck as the retrieval of preinstructed responses that has been the mainstay of attention and performance research.
Stimulus-Related Inhibition of Task Set During Task Switching
Authors: Sdoia Stefano , Ferlazzo Fabio
Published: June 2008

Performance after a shifting of task is supported by the inhibition of the executed task, as revealed by slower reaction times (RTs) on alternating compared to nonalternating task sequences (ABA vs CBA). In the present study we investigated the role of stimulus processing in the establishment of task inhibition during task switching, irrespective of the response selection process. Comparing performance on AbA and CbA task sequences within a procedure in which the b-task only involved stimulus encoding processes for later comparison but response selection did not occur, we found slower RTs on AbA compared to CbA task sequences. This revealed that inhibition of the executed task can be triggered at the stimulus processing stage of the new task. In accordance, inhibition only emerged when interference between tasks occurred at the stimulus level, due to stimuli having features relevant for both the executed and the upcoming task.
Seeing the Forest Before the Trees Depends on Individual Field-Dependency Characteristics
Authors: Poirel Nicolas , Pineau Arlette , Jobard Gael , Mellet Emmanuel
Published: June 2008

Numerous studies have demonstrated that the well-known global precedence effect, characterized by a visual bias toward global information, is highly dependent on stimulus characteristics ( Kimchi, 1992 ). Despite the extensive global-local literature, few studies have investigated how interindividual characteristics could affect the global precedence effect. In this framework, we studied the relationship between global-local visual biases and the Group Embedded Figure Test (GEFT), a standardized measure of field dependency. Data from 34 participants were consistent with the idea that an individual’s bias toward the global level is linearly related to his or her degree of field dependence. Given the important role that global-local visual skills play during visuospatial tasks, these results have important implications for future research in this area.
Hindsight Bias and the Activation of Counterfactual Mind-Sets
Authors: Nestler Steffen , von Collani Gernot
Published: June 2008

Previous research has shown that conditional counterfactuals are positively related to the magnitude of creeping determinism. Unlike previous experiments which show this increased hindsight bias to occur after exceptional antecedents, we investigated another possible factor, namely a prior activation of a counterfactual mind-set. We investigated our prediction using a hypothetical scenario. Prior to reading the hindsight scenario some participants were asked to solve a scrambled-sentence test including conditional counterfactual sentences. Results of two experiments were consistent with our predictions: Participants that solved the scrambled-sentence test perceived the outcome to be more inevitable than participants in a no-outcome control condition and participants in a no-prime control condition. Furthermore, we found that this increase in creeping determinism was mediated by the perceived causal strength of the target antecedent for the occurrence of the outcome, and that the priming-effect did not occur when an unconditional counterfactual mind-set was activated before. The results are interpreted as supporting a causal-model theory of the hindsight bias.
Orthographic Overlap and Category Size in Unconscious Category Priming
Authors: Abrams Richard L.
Published: June 2008

Van den Bussche and Reynvoet (2007, Experiment 1 ) report unconscious priming of comparable magnitude from novel words belonging to small and large categories, evidence that they interpret as demonstrating independence from category size of priming that involves semantic analysis. Three experiments raise the possibility that the findings in Experiment 1c of Van den Bussche and Reynvoet reflect subword processing, not semantic analysis. In Experiments 1 and 2, priming was obtained from primes and targets that shared approximately the same degree of subword features as in Experiment 1c of Van den Bussche and Reynvoet, but no priming occurred when sharing of features was minimized. Experiment 3 demonstrated priming driven by subword features when those features were set in opposition to whole-word meaning. These results indicate that orthographic overlap must be considered a potentially important confound in findings that ostensibly support priming mediated by semantic analysis.
The magmatic plumbing of the submarine Hachijo NW volcanic chain, Hachijojima, Japan: Long‐distance magma transport?
Authors: Ishizuka Osamu , Geshi Nobuo , Itoh Jun'ichi , Kawanabe Yoshihisa , TuZino Taqumi
Published: June 2008

Recent geophysical observations on basaltic composite volcanoes in Izu‐Bonin arc reveal the process of long‐distance lateral magma transport within arc crust. To clarify a long‐distance magma transport system of the basaltic arc volcano from geological and petrological aspects, we investigated 20‐km‐long submarine volcanic chains (Hachijo NW chain and Hachijo‐kojima chain) and cones on the northeastern slope (NE edifices) as well as subaerial satellite cones nested Hachijo Nishiyama volcano in the northern Izu arc front. Basalts from Hachijo NW chain have more primitive composition than those from other edifices. The composition of the Hachijo NW chain basalts is controlled by fractional crystallization, while plagioclase accumulation occurred in NE edifices and subaerial satellite cones. Trace element and isotopic characteristics indicate that the same basaltic primary magma is involved in all sections of the volcano. This leads us to consider that magma was transported long distances between the Nishiyama volcano and the Hachijo NW chain. Primitive magma was laterally transported NNW for at least 20 km in the middle to lower crust (10–20 km deep) from Nishiyama volcano with only minimal crustal level modifications and formed Hachijo NW chain. On the other hand, magmas experienced crystal fractionation and accumulation at shallow magma chamber beneath Nishiyama volcano seems to have been transported in a short distance (<5 km) and formed NE trending edifices and subaerial satellite cones. The long‐distance magma transport seems to be controlled by a regional extensional stress regime, while short‐distance transport may be controlled by local stress regime affected by load of main volcanic edifice.
Extreme spatial and temporal variability of hydrothermal microbial mat communities along the Mariana Island Arc and southern Mariana back‐arc system
Authors: Davis Richard E. , Moyer Craig L.
Published: June 2008

Twenty‐five microbial communities were sampled from 18 different hydrothermal systems located at seven different sites along the Mariana Island Arc and at a single site from the southern Mariana Spreading Center over a 3‐year period. Terminal restriction fragment length polymorphism (T‐RFLP) analysis of the small subunit rRNA gene revealed that the microbial community diversity is much greater along the Mariana Arc/back‐arc than at either hot spot volcanoes or mid‐ocean ridges along the same spatial scale. Cluster analysis of T‐RFLP fingerprints reveals the microbial communities formed three distinct clusters designated Mariana clusters I, II, and III. Microbial communities in Mariana Cluster I are all associated with iron‐rich microbial mats and are dominated by members of the ζ‐Proteobacteria and by unique phylotypes clustering deeply in the δ‐Proteobacteria and within the Nitrospira division. Mariana Cluster II communities are all from shallow hydrothermal systems and mostly from colder sediments or microbial mats that are dominated by putative heterotrophic phylotypes usually associated with seawater and sediments not generally associated with hydrothermal fluid inputs. Mariana Cluster III is generally from much hotter vent sites and is dominated by sulfur‐oxidizing ɛ‐Proteobacteria. Quantitative‐polymerase chain reaction (Q‐PCR) of Archaeal abundance reveal that all of the microbial communities are dominated by members of the Bacterial domain. Sampling of microbial mats from Iceberg Vent at NW Rota‐1 in 2004 and again in 2006 reveal the community has shown a transition from Caminibacter group ɛ‐Proteobacteria phylotypes to a mixed population of Caminibacter, Sulfurovum, and Sulfurimonas group ɛ‐Proteobacteria.
High Resolution Dynamics Limb Sounder: Experiment overview, recovery, and validation of initial temperature data
Authors: Gille John , Barnett John , Arter Philip , Barker Marion , Bernath Peter , Boone Chris , Cavanaugh Charles , Chow Jonathan , Coffey Michael , Craft James , Craig Cheryl , Dials Michael , Dean Vincil , Eden Thomas , Edwards D. P. , Francis Gene , Halvorson Chris , Harvey Lynn , Hepplewhite Christopher , Khosravi Rashid , Kinnison Douglas , Krinsky Charles , Lambert Alyn , Lee Hyunah , Lyjak Lawrence , Loh Joanne , Mankin William , Massie Steven , McInerney Joseph , Moorhouse Joseph , Nardi Bruno , Packman Daniel , Randall Cora , Reburn Jolyon , Rudolf Wayne , Schwartz Michael , Serafin John , Stone Kenneth , Torpy Brendan , Walker Kaley , Waterfall Alison , Watkins Robert , Whitney John , Woodard Douglas , Young Gregory
Published: June 2008

The High Resolution Dynamics Limb Sounder (HIRDLS) experiment was designed to provide global temperature and composition data on the region from the upper troposphere to the mesopause with vertical and horizontal resolution not previously available. The science objectives are the study of small‐scale dynamics and transports, including stratosphere‐troposphere exchange, upper troposphere/lower stratosphere chemistry, aerosol, cirrus and PSC distributions, and gravity waves. The instrument features 21 channels, low noise levels, high vertical resolution, and a mechanical cooler for long life. During launch most of the optical aperture became obscured, so that only a potion of an optical beam width at a large azimuth from the orbital plane on the side away from the Sun can see the atmosphere. Irrecoverable loss of capabilities include limitation of coverage to the region 65°S–82°N and inability to obtain longitudinal resolution finer than an orbital spacing. While this optical blockage also impacted radiometric performance, extensive effort has gone into developing corrections for the several effects of the obstruction, so that radiances from some of the channels can be put into retrievals for temperature. Changes were also necessary for the retrieval algorithm. The validation of the resulting temperature retrievals is presented to demonstrate the effectiveness of these corrections. The random errors range from ∼0.5 K at 20 km to ∼1.0 at 60 km, close to those predicted. Comparisons with high‐resolution radiosondes, lidars, ACE‐FTS, and ECMWF analyses give a consistent picture of HIRDLS temperatures being 1–2 K warm from 200 to 10 hPa and within ±2 K of standards from 200 to 2 hPa (but warmer in the region of the tropical tropopause), above which HIRDLS appears to be cold. Comparisons show that both COSMIC and HIRDLS can see small vertical features down to about 2 km wavelength. While further improvements in the data are expected, these data will allow HIRDLS to provide important support toward reaching the Aura objectives.
Weighted near‐field focusing in an array‐based GPR
Authors: Savelyev Timofey G. , Yarovoy Alexander G. , Ligthart Leo P.
Published: June 2008

This paper presents a 3‐D imaging technique for an ultra‐wideband (UWB) ground penetrating radar (GPR) with a single transmit antenna and a linear receive array. The video impulse GPR working in the frequency band of 0.3–3 GHz has been designed in IRCTR for landmine detection, i.e., for a near‐field application. Installed on a vehicle it can image in one mechanical scan a strip of 84 cm width due to the length of array aperture. The imaging is done by software means only. The developed imaging technique combines a real aperture focusing in the array plane with a synthetic aperture focusing in the mechanical scan direction. To compensate for parasitic time delays in the array channels, a calibration procedure is also described. Owing to directional properties of transmit antenna, the distribution of signal strength over the array is nonuniform that requires an amplitude correction when focusing the real aperture. The authors analyzed how this affects the footprint of the focused array, its cross‐range resolution capability and the image quality of antipersonnel plastic landmines which were buried under different array channels. The analysis bases on experimental data sets acquired in the facilities of IRCTR and TNO‐DSS. As a result, the authors propose a weighted array focusing that improves the cross‐range resolution and provides proper imaging of typical buried landmines.
Infiltration from an impoundment for coal‐bed natural gas, Powder River Basin, Wyoming: Evolution of water and sediment chemistry
Authors: Healy Richard W. , Rice Cynthia A. , Bartos Timothy T. , McKinley Michael P.
Published: June 2008

Development of coal‐bed natural gas (CBNG) in the Powder River Basin, Wyoming, has increased substantially in recent years. Among environmental concerns associated with this development is the fate of groundwater removed with the gas. A preferred water‐management option is storage in surface impoundments. As of January 2007, permits for more than 4000 impoundments had been issued within Wyoming. A study was conducted on changes in water and sediment chemistry as water from an impoundment infiltrated the subsurface. Sediment cores were collected prior to operation of the impoundment and after its closure and reclamation. Suction lysimeters were used to collect water samples from beneath the impoundment. Large amounts of chloride (12,300 kg) and nitrate (13,500 kg as N), most of which accumulated naturally in the sediments over thousands of years, were released into groundwater by infiltrating water. Nitrate was more readily flushed from the sediments than chloride. If sediments at other impoundment locations contain similar amounts of chloride and nitrate, impoundments already permitted could release over 48 × 106 kg of chloride and 52 × 106 kg of nitrate into groundwater in the basin. A solute plume with total dissolved solid (TDS) concentrations at times exceeding 100,000 mg/L was created in the subsurface. TDS concentrations in the plume were substantially greater than those in the CBNG water (about 2300 mg/L) and in the ambient shallow groundwater (about 8000 mg/L). Sulfate, sodium, and magnesium are the dominant ions in the plume. The elevated concentrations are attributed to cation‐exchange‐enhanced gypsum dissolution. As gypsum dissolves, calcium goes into solution and is exchanged for sodium and magnesium on clays. Removal of calcium from solution allows further gypsum dissolution.
A stochastic nonparametric approach for streamflow generation combining observational and paleoreconstructed data
Authors: Prairie James , Nowak Kenneth , Rajagopalan Balaji , Lall Upmanu , Fulp Terrance
Published: June 2008

The Colorado River basin experienced the worst drought on record during 2000–2004. Paleoreconstructions of streamflow for the preobservational period show droughts of greater magnitude and duration, indicating that the recent drought is not unusual. The rich information provided by paleoreconstructions should be incorporated in stochastic streamflow models, enabling the generation of realistic flow scenarios required for robust water resources planning and management. However, the magnitudes of reconstructed streamflow have a high degree of uncertainty. This apparent weakness of the paleodata has made their use in water resources planning contentious, despite their availability for many decades. However, few contest the accuracy of hydrologic state (i.e., dry and wet periods). A key question is how to combine the long paleoreconstructed streamflow information of lower reliability with the shorter observational data to develop a framework for streamflow simulation. We propose a unique stochastic streamflow simulation framework combining these two data sets. This has two components: (1) a nonhomogeneous Markov chain model, developed using the paleodata, which is used to simulate the hydrologic state, and (2) a nonparametric K‐nearest neighbor (K‐NN) time series bootstrap of observational flow magnitudes conditioned on the hydrologic state, thus combining the respective strengths of the two data sets. The framework is demonstrated for the Lees Ferry, Arizona, stream gauge on the Colorado River. The simulations show the ability to reproduce relevant statistics of the observational period and generate a rich variety of wet and dry sequences for use in sustainable management of water resources.
Globally significant oceanic source of organic carbon aerosol
Authors: Spracklen Dominick V. , Arnold Steve R. , Sciare Jean , Carslaw Kenneth S. , Pio Casimiro
Published: June 2008

Significant concentrations of organic carbon (OC) aerosol are observed at three oceanic surface sites (Amsterdam Island, Azores and Mace Head). Two global chemical transport models (CTMs) underpredict OC concentrations at these sites (normalised mean bias of −67% and −58%). During periods of high biological activity monthly mean concentrations are underpredicted by a factor of 5–20. At Amsterdam Island and Mace Head, observed OC correlates well (R2 = 0.61–0.77) with back‐trajectory weighted chlorophyll‐a, suggesting an oceanic OC source driven by biological activity. We use a combination of remote sensed chlorophyll‐a, back trajectories and observed OC to derive an empirical relation between chlorophyll‐a and the total oceanic OC emission flux. Using the GEOS‐chem CTM we show a global oceanic OC emission, from primary and secondary sources, of ∼8 Tg/year matches observations. This emission is comparable in magnitude to the fossil fuel OC source and increases the simulated global OC burden by 20%.
Shoaling of the off‐equatorial south Indian Ocean thermocline: Is it driven by anthropogenic forcing?
Authors: Cai Wenju , Sullivan Arnold , Cowan Tim
Published: June 2008

Surface warming since 1950 in the off‐equatorial south Indian Ocean (IO) occurs without a consistent surface heat flux trend, and is accompanied by a shoaling thermocline. The associated dynamics have not been fully explored. Using 20th century climate model experiments, we test if the shoaling thermocline is attributable to a transmission from the Pacific, where a similar shoaling occurs, and whether it is climate change‐induced. A 22‐model average produces no such signal. An average of a subset of models that better simulate El Niño‐Southern Oscillation (ENSO) and its transmission produces the right direction of the IO thermocline trends. The shoaling in this subset average, taken as anthropogenically induced, is far weaker than the observed, suggesting a significant multidecadal variability component in the observed changes. The Pacific contribution increases with a stronger model ENSO amplitude and broader meridional structure, highlighting the importance of realistic ENSO simulations in modelling long‐term change in the IO.
Development and initial application of the sesquiversion of MADRID
Authors: Pun B. K.
Published: June 2008

Organic aerosol (OA) models are typically formulated on the basis of empirical parameters or from first principles based on molecular constituents and properties. The overarching theme of sesqui‐MADRID is the representation of primary and secondary organic aerosol constituents using surrogate molecular structures. Empirical partitioning characteristics guide the selection of surrogate secondary OA (SOA). Semivolatile primary OA (POA) are represented by selective compounds of key source types. The assignment of surrogate structures allows the use of group contribution methods for the calculation of thermodynamic properties such as activity coefficients, vapor pressures, and enthalpies of vaporization. A new activity coefficient model represents the interactions among POA, SOA, and water. The inclusion of water increases the total OA concentration by increasing the absorbing medium. If activity coefficients are assumed to be unity, OA increases substantially. Treatment of nonideality is essential in OA modules. When thermodynamically favorable, two phases with different hydrophobicity are modeled. Phase separation of OA is more common when water is considered as part of the absorbing medium than when it is not. Phase separation results in a small increase in total OA, because hydrophobic and hydrophilic compounds can exist in two liquid phases rather than repel each other in a single phase. Allowing POA to evaporate reduces the fraction of POA relative to SOA. The decrease can lead to a less than proportional decrease (or an increase) in total OA due to changes in composition, activity coefficients, and partitioning of individual constituents. A three‐dimensional demonstration of sesqui‐MADRID for a typical summer day shows an overall increase in OA in the southeastern United States compared to an empirical approach. Sesqui‐MADRID predicts higher contributions from volatile and hydrophilic constituents and similar concentrations for constituents that are hydrophobic and less volatile.
Seasonal dynamics of the endosymbiotic, nitrogen-fixing cyanobacterium Richelia intracellularis in the eastern Mediterranean Sea
Authors: Zeev Edo Bar , Yogev Tali , Man-Aharonovich Dikla , Kress Nurit , Herut Barak , Béjà Oded , Berman-Frank Ilana
Published: June 2008

Biological nitrogen fixation has been suggested as an important source of nitrogen for the ultra-oligotrophic waters of the Levantine Basin of the Mediterranean Sea. In this study, we identify and characterize the spatial and temporal distribution of the N-fixing (diazotrophic) cyanobacterium Richelia intracellularis. R. intracellularis is usually found as an endosymbiont within diatoms such as Rhizosolenia spp and Hemiaulus spp. and is an important diazotroph in marine tropical oceans. In this study, two stations off the Mediterranean coast of Israel were sampled monthly during 2005–2007. R. intracellularis was identified by microscopy and by reverse transcribed-PCR which confirmed a 98.8% identity with known nifH sequences of R. intracellularis from around the world. The diatom–diazotroph associations were found throughout the year peaking during autumn (October–November) at both stations. Abundance of R. intracellularis ranged from 10 to 55 heterocysts l−1 and correlated positively with the dissolved Si(OH)4/(NO3+NO2) ratio in surface waters. Although the rates of nitrogen fixation were very low, averaging ∼1.1 nmol N l−1 day−1 for the R. intracellularis size fraction (>10 μm) from surface waters, they correlated positively with heterocyst counts during thermal stratification. The lack of large-scale diatom–diazotroph blooms and the low rates of nitrogen fixation by these diazotrophs may result from the P-starved conditions affecting the Levantine basin.
Microbial ecology of the equine hindgut during oligofructose-induced laminitis
Authors: Milinovich Gabriel J , Burrell Paul C , Pollitt Christopher C , Klieve Athol V , Blackall Linda L , Ouwerkerk Diane , Woodland Erika , Trott Darren J
Published: June 2008

Alimentary carbohydrate overload is a significant cause of laminitis in horses and is correlated with drastic shifts in the composition of hindgut microbiota. Equine hindgut streptococcal species (EHSS), predominantly Streptococcus lutetiensis, have been shown to be the most common microorganisms culturable from the equine caecum prior to the onset of laminitis. However, the inherent biases of culture-based methods are estimated to preclude up to 70% of the normal caecal microbiota. The objective of this study was to evaluate bacterial population shifts occurring in the equine caecum throughout the course of oligofructose-induced laminitis using several culture-independent techniques and to correlate these with caecal lactate, volatile fatty acid and degrees of polymerization 3–7 fructo-oligosaccharide concentrations. Our data conclusively show that of the total microbiota present in the equine hindgut, the EHSS S. lutetiensis is the predominant microorganism that proliferates prior to the onset of laminitis, utilizing oligofructose to produce large quantities of lactate. Population shifts in lactobacilli and Escherichia coli subpopulations occur secondarily to the EHSS population shifts, thus confirming that lactobacilli and coliforms have no role in laminitis. A large, curved, Gram-negative rod previously observed during the early phases of laminitis induction was most closely related to the Anaerovibrio genus and most likely represents a new, yet to be cultured, genus and species. Correlation of fluorescence in situ hybridization and quantitative real-time PCR results provide evidence supporting the hypothesis that laminitis is associated with the death en masse and rapid cell lysis of EHSS. If EHSS are lysed, liberated cellular components may initiate laminitis.
Sociobiological Control of Plasmid copy number
Authors: Watve Mukta , Watve Milind
Published: June 2008

Background:

All known mechanisms and genes responsible for the regulation of plasmid replication lie with the plasmid rather than the chromosome. It is possible therefore that there can be copy-up mutants. Copy-up mutants will have within host selective advantage. This would eventually result into instability of bacteria-plasmid association. In spite of this possibility low copy number plasmids appear to exist stably in host populations. We examined this paradox using a computer simulation model.

Model:

Our multilevel selection model assumes a wild type with tightly regulated replication to ensure low copy number. A mutant with slightly relaxed replication regulation can act as a “cheater” or “selfish” plasmid and can enjoy a greater within-host-fitness. However the host of a cheater plasmid has to pay a greater cost. As a result, in host level competition, host cell with low copy number plasmid has a greater fitness. Furthermore, another mutant that has lost the genes required for conjugation was introduced in the model. The non-conjugal mutant was assumed to undergo conjugal transfer in the presence of another conjugal plasmid in the host cell.

Results:

The simulatons showed that if the cost of carrying a plasmid was low, the copy-up mutant could drive the wild type to extinction or very low frequencies. Consequently, another mutant with a higher copy number could invade the first invader. This process could result into an increasing copy number. However above a certain copy number within-host selection was overcompensated by host level selection leading to a rock-paper-scissor (RPS) like situation. The RPS situation allowed the coexistence of high and low copy number plasmids. The non-conjugal “hypercheaters” could further arrest the copy numbers to a substantially lower level.

Conclusions:

These sociobiological interactions might explain the stability of copy numbers better than molecular mechanisms of replication regulation alone.
Ecoinformatics: where are we, where do we want to go, and how to reach there.
Authors: Krishna Abhay
Published: June 2008

Compared to other natural sciences ecological sciences has always been about seeing the bigger picture. The realization that local actions can have global impact has been the hallmark of ecological research. This integrative view is getting more and more accepted now with the recognition that whole is definitely more then sum of its parts. Advancement in computer sciences has now made it possible to comprehend the complexity arising from an integrative approach. This has given rise to a field interfacing computer science and ecological sciences called Ecoinformatics. The other popular parallel and more mature field is bioinformatics or computational biology. The presentation will take the audience on an Ecoinformatics tour touching on present status of Ecoinformatics tools and applications, a futuristic account of where Ecoinformatics is heading, and the pragmatic step by step method to transform future into reality; applying insights from lessons learnt from a more mature interface science 'Bioinformatics'. Audience will be introduced to Ecoinformatics projects namely Kepler, Vegbank, Jalama, Knowledge network for biocomplexity (KNB), Science Environment for Ecological Knowledge (SEEK). The presentation will also explore the importance of Ecoinformatics for the icons and upstarts in ecology.
Archaeological Chemistry
Authors: Pollard A Mark , Heron Carl , Gillard R D
Published: June 2008

The application of chemistry within archaeology is an important and fascinating area. It allows the archaeologist to answer such questions as "what is this artefact made of?", "where did it come from?" and "how has it been changed through burial in the ground?", providing pointers to the earliest history of mankind. Archaeological Chemistry begins with a brief description of the goals and history of archaeological science, and the place of chemistry within it. It sets out the most widely used analytical techniques in archaeology and compares them in the light of relevant applications. The book includes an analysis of several specific archaeological investigations in which chemistry has been employed in tracing the origins of or in preserving artefacts. The choice of these investigations conforms to themes based on analytical techniques, and includes chapters on obsidian, ceramics, glass, metals and resins. Finally, it suggests a future role for chemical and biochemical applications in archaeology. Archaeological Chemistry enables scientists to tackle the fundamental issues of chemical change in the archaeological materials, in order to advance the study of the past. It will prove an essential companion to students in archaeological science and chemistry, field and museum archaeologists, and all those involved in conserving human artefacts.
Formulation of improved basis sets for the study of polymer dynamics through diffusion theory methods
Authors: Gaspari Roberto , Rapallo Arnaldo
Published: June 2008

In this work a new method is proposed for the choice of basis functions in diffusion theory (DT) calculations. This method, named hybrid basis approach (HBA), combines the two previously adopted long time sorting procedure (LTSP) and maximum correlation approximation (MCA) techniques; the first emphasizing contributions from the long time dynamics, the latter being based on the local correlations along the chain. In order to fulfill this task, the HBA procedure employs a first order basis set corresponding to a high order MCA one and generates upper order approximations according to LTSP. A test of the method is made first on a melt of cis-1,4-polyisoprene decamers where HBA and LTSP are compared in terms of efficiency. Both convergence properties and numerical stability are improved by the use of the HBA basis set whose performance is evaluated on local dynamics, by computing the correlation times of selected bond vectors along the chain, and on global ones, through the eigenvalues of the diffusion operator L. Further use of the DT with a HBA basis set has been made on a 71-mer of syndiotactic trans-1,2-polypentadiene in toluene solution, whose dynamical properties have been computed with a high order calculation and compared to the “numerical experiment” provided by the molecular dynamics (MD) simulation in explicit solvent. The necessary equilibrium averages have been obtained by a vacuum trajectory of the chain where solvent effects on conformational properties have been reproduced with a proper screening of the nonbonded interactions, corresponding to a definite value of the mean radius of gyration of the polymer in vacuum. Results show a very good agreement between DT calculations and the MD numerical experiment. This suggests a further use of DT methods with the necessary input quantities obtained by the only knowledge of some experimental values, i.e., the mean radius of gyration of the chain and the viscosity of the solution, and by a suitable vacuum trajectory, with great savings in computational time required. This offers a theoretical bridge between the experimental static and dynamical properties of polymers.
Spontaneous rotation sources in a quiescent tokamak edge plasma
Authors: Chang C. S. , Ku S.
Published: June 2008

Spontaneous rotation sources in a quiescent tokamak edge plasma are studied without an external momentum source, such as, beam injected or wall-born neutrals. Discussions are based upon example neoclassical solutions from an edge gyrokinetic particle code. The main study is performed in a DIII-D plasma [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] with the ion Grad-B drift directed toward the single-null divertor. Comparison with a reversed Grad-B drift case is also shown. It is found that there is a robust spontaneous co-current toroidal plasma rotation source in the far scrape-off plasma due to the wall sheath effect. As the edge pedestal width becomes narrower, the co-current rotation in the far scrape-off becomes weaker, but there appears a stronger co-current rotation in the pedestal top/shoulder from the X-point orbit loss effect, possibly providing a co-rotation boundary condition to the core plasma. Reversal of the magnetic field and plasma current brings down the overall co-rotation, especially in the far scrape-off plasma.
Modeling of ion heating from viscous damping of reconnection flows in the reversed field pinch
Authors: Svidzinski V. A. , Fiksel G. , Mirnov V. V. , Prager S. C.
Published: June 2008

Strong self-heating of ions is observed in the reversed field pinch (RFP). During a sawtooth crash in the Madison Symmetric Torus RFP, the ion temperature can spontaneously double in ∼100μs. It is also observed that high Z impurities are heated more strongly than bulk ions. The possibility of ion heating due to tearing instabilities at sawtooth crash is examined. Heating scenarios due to viscous damping of strongly localized perpendicular and parallel flows driven in the vicinity of resonant surface in tearing mode are considered. Flow amplitudes and spatial scales are estimated from linear and nonlinear resistive magnetohydrodynamic modeling. The heating rates are found from kinetic models with different levels of approximation, up to solving kinetic equation with a Landau collision operator. Results show reasonable agreement of the modeled impurity heating rate with the experiment, while the estimated bulk ions heating is somewhat weaker than in the experiment. Further theoretical and experimental study are required for a more definite conclusion as to whether it is the main ion heating mechanism or if there is some other important ion heating scenario.
Magnetoresistance in granular magnetic tunnel junctions with Fe nanoparticles embedded in ZnSe semiconducting epilayer
Authors: de Moraes A. R. , Saul C. K. , Mosca D. H. , Varalda J. , Schio P. , de Oliveira A. J. A. , Canesqui M. A. , Garcia V. , Demaille D. , Eddrief M. , Etgens V. H. , George J. M.
Published: June 2008

We have investigated transport properties of iron (Fe) nanoparticles embedded in zinc selenide (ZnSe) semiconducting epilayers prepared by molecular beam epitaxy. Both positive and negative tunneling magnetoresistances (TMRs) were measured depending on the applied voltage biases and on the temperature. A slow reduction of the TMR magnitude with temperature was detected and it could be explained in terms of a crossover between direct/resonant tunneling and variable range hopping. The temperature behavior of the magnetoresistance is a clear signature of tunneling and hopping mechanisms mediated by the ZnSe barrier localized states.
Valence electronic properties of n-channel organic materials based on fluorinated derivatives of perylene diimides
Authors: Dou Weidong , Guan Dandan , Song Fei , Li Nana , Zhang Hanjie , Li Haiyang , He Pimo , Chen Hongzheng , Bao Shining , Hofmann Philip
Published: June 2008

The valence electronic states of three kinds of fluorinated derivatives of perylene diimides, D2MFPP, D3MFPP, and D4MFPP, on Cu(110) and SiO2∕Si surface were studied by photoemission and density functional calculations. When these organic molecules were deposited on the Cu(110) and thermally oxidized SiO2 surfaces, five well-resolved photoemission features originating from the molecules were observed. On Cu(110) surface, two emission features with π-like character increased their binding energy with increasing the coverage of organic molecule, indicating a strong interaction between the organic molecules and Cu substrate. The density functional calculations suggest flat-lying adsorption geometry for D3MFPP and D4MFPP on Cu(110) surface.
Anisotropy of velocity spectra in quasistatic magnetohydrodynamic turbulence
Authors: Burattini Paolo , Kinet Maxime , Carati Daniele , Knaepen Bernard
Published: June 2008

We consider homogeneous magnetohydrodynamic turbulence subject to a uniform magnetic field B at low magnetic Reynolds number. The flow, which is computed with direct simulations, is statistically stationary. By examining one-dimensional velocity spectra, we show that the anisotropy induced by B is scale dependent; at small scales, the velocity component parallel to B is more attenuated than that perpendicular to B. Although in contrast with results in the literature based on three-dimensional spectra, the present conclusion is demonstrated to be consistent with the effective turbulent energy distribution in Fourier space and the definition of the one-dimensional spectrum. Further, it is found that the anisotropy is minimum in a range of length scales about the size of the Taylor microscale. It is argued that this range is the vestige of the inertial range, which is gradually destroyed as B increases.