Showing papers by "University of New Hampshire published in 2004"

Nitrogen cycles: past, present, and future

Abstract: This paper contrasts the natural and anthropogenic controls on the conversion of unreactive N2 to more reactive forms of nitrogen (Nr). A variety of data sets are used to construct global N budgets for 1860 and the early 1990s and to make projections for the global N budget in 2050. Regional N budgets for Asia, North America, and other major regions for the early 1990s, as well as the marine N budget, are presented to highlight the dominant fluxes of nitrogen in each region. Important findings are that human activities increasingly dominate the N budget at the global and at most regional scales, the terrestrial and open ocean N budgets are essentially dis- connected, and the fixed forms of N are accumulating in most environmental reservoirs. The largest uncertainties in our understanding of the N budget at most scales are the rates of natural biological nitrogen fixation, the amount of Nr storage in most environmental reservoirs, and the production rates of N2 by denitrification.

Conceptualizing simultaneity: a transnational social field perspective on society

Abstract: This article explores the social theory and consequent methodology that underpins studies of transnational migration. First, we propose a social field approach to the study of migration and distinguish between ways of being and ways of belonging in that field. Second, we argue that assimilation and enduring transnational ties are neither incompatible nor binary opposites. Third, we highlight social processes and institutions that are routinely obscured by traditional migration scholarship but that become clear when we use a transnational lens. Finally, we locate our approach to migration research within a larger intellectual project, taken up by scholars of transnational processes in many fields, to rethink and reformulate the concept of society such that it is no longer automatically equated with the boundaries of a single nationstate. Social scientists have long been interested in how immigrants are incorporated into new countries. In Germany and France, scholars’ expectations that foreigners will assimilate is a central piece of public policy. In the United States, immigration scholars initially argued that to move up the socioeconomic ladder, immigrants would have to abandon their unique customs, language, values, and homeland ties and identities. Even when remaining ethnic became more acceptable, most researchers assumed that the importance of homeland ties would eventually fade. To be Italian American or Irish American would ultimately reflect ethnic pride within a multicultural United States rather than enduring relations to an ancestral land. Now scholars increasingly recognize that some migrants and their descendants remain strongly influenced by their continuing ties to their home country or by social networks that stretch across national borders. They see

Emotional Intelligence: Theory, Findings, and Implications

Abstract: (2004). TARGET ARTICLES: 'Emotional Intelligence: Theory, Findings, and Implications' Psychological Inquiry: Vol. 15, No. 3, pp. 197-215.

Online aggressor/targets, aggressors, and targets: a comparison of associated youth characteristics

Abstract: Background: While most youth report positive experiences and activities online, little is known about experiences of Internet victimization and associated correlates of youth, specifically in regards to Internet harassment. Methods: The Youth Internet Safety Survey is a cross-sectional, nationally representative telephone survey of young regular Internet users in the United States. Interviews were conducted between the fall of 1999 and the spring of 2000 and examined characteristics of Internet harassment, unwanted exposure to sexual material, and sexual solicitation that had occurred on the Internet in the previous year. One thousand, five hundred and one regular Internet users between the ages of 10 and 17 years were interviewed, along with one parent or guardian. To assess the characteristics surrounding Internet harassment, four groups of youth were compared: 1) targets of aggression (having been threatened or embarrassed by someone; or feeling worried or threatened by someone’s actions); 2) online aggressors (making rude or nasty comments; or harassing or embarrassing someone with whom the youth was mad at); 3) aggressor/targets (youth who report both being an aggressor as well as a target of Internet harassment); and 4) non-harassment involved youth (being neither a target nor an aggressor online). Results: Of the 19% of young regular Internet users involved in online aggression, 3% were aggressor/targets, 4% reported being targets only, and 12% reported being online aggressors only. Youth aggressor/targets reported characteristics similar to conventional bully/victim youth, including many commonalities with aggressor-only youth, and significant psychosocial challenge. Conclusions: Youth aggressor/targets are intense users of the Internet who view themselves as capable web users. Beyond this, however, these youth report significant psychosocial challenge, including depressive symptomatology, problem behavior, and targeting of traditional bullying. Implications for intervention are discussed. Keywords: Internet, bully, adolescence, computers, depression, child development. Abbreviations: YISS: Youth Internet Safety Survey; AOR: Adjusted Odds Ratio.

Adaptive evolution and explosive speciation : the cichlid fish model

Abstract: The cost of DNA sequencing continues to fall, which makes it feasible to develop genomic resources for new model species that are well suited for studying questions in evolutionary biology. The thousands of closely related cichlid fishes in the lakes of East Africa are an ideal model system for understanding the genetic basis of vertebrate speciation. Genomic techniques are helping to integrate empirical and theoretical studies by identifying the genes that underlie the phenotypic differences among species.

Lysosomal Glycosphingolipid Recognition by NKT Cells

Abstract: NKT cells represent a distinct lineage of T cells that coexpress a conserved αβ T cell receptor (TCR) and natural killer (NK) receptors. Although the TCR of NKT cells is characteristically autoreactive to CD1d, a lipid-presenting molecule, endogenous ligands for these cells have not been identified. We show that a lysosomal glycosphingolipid of previously unknown function, isoglobotrihexosylceramide (iGb3), is recognized both by mouse and human NKT cells. Impaired generation of lysosomal iGb3 in mice lacking β-hexosaminidase b results in severe NKT cell deficiency, suggesting that this lipid also mediates development of NKT cells in the mouse. We suggest that expression of iGb3 in peripheral tissues may be involved in controlling NKT cell responses to infections and malignancy and in autoimmunity.

A short form of the Revised Conflict Tactics Scales, and typologies for severity and mutuality.

Abstract: The revised Conflict Tactics Scales (CTS2) is the most widely used instrument for measuring intimate partner violence. This article presents a short form to enable the CTS2 to be used when testing time is very limited. It also presents procedures that can be used with either the full test or the short form to classify individuals on the basis of severity of behavior toward a partner or by a partner, and to classify couples on the basis of mutuality or symmetry in the behaviors measured by the CTS2. The results indicate that the short form is comparable in validity to the full CTS2. Although the short form does not identify as many cases of partner violence as the full scale, it does identify a large number of cases and if there is insufficient time for the full scale, can be a useful screening instrument.

Type-A Arabidopsis response regulators are partially redundant negative regulators of cytokinin signaling.

Abstract: Type-A Arabidopsis (Arabidopsis thaliana) response regulators (ARRs) are a family of 10 genes that are rapidly induced by cytokinin and are highly similar to bacterial two-component response regulators. We have isolated T-DNA insertions in six of the type-A ARRs and constructed multiple insertional mutants, including the arr3,4,5,6,8,9 hextuple mutant. Single arr mutants were indistinguishable from the wild type in various cytokinin assays; double and higher order arr mutants showed progressively increasing sensitivity to cytokinin, indicating functional overlap among type-A ARRs and that these genes act as negative regulators of cytokinin responses. The induction of cytokinin primary response genes was amplified in arr mutants, indicating that the primary response to cytokinin is affected. Spatial patterns of ARR gene expression were consistent with partially redundant function of these genes in cytokinin signaling. The arr mutants show altered red light sensitivity, suggesting a general involvement of type-A ARRs in light signal transduction. Further, morphological phenotypes of some arr mutants suggest complex regulatory interactions and gene-specific functions among family members.

Prevalence of Violence Against Dating Partners by Male and Female University Students Worldwide

Abstract: This article presents rates of violence against dating partners by students at 31 universities in 16 countries (5 in Asia and the Middle East, 2 in Australia-New Zealand, 6 in Europe, 2 in Latin America, 16 in North America). Assault and injury rates are presented for males and females at each of the 31 universities. At the median university, 29% of the students physically assaulted a dating partner in the previous 12 months (range = 17% to 45%) and 7% had physically injured a partner (range = 2% to 20%). The results reveal both important differences and similarities between universities. Perhaps the most important similarity is the high rate of assault perpetrated by both male and female students in all the countries.

Bystander education: Bringing a broader community perspective to sexual violence prevention

Abstract: Recent research documents the problem of sexual violence across communities, often finding its causes to be embedded in community and cultural norms, thus demonstrating the need for community-focused solutions. In this article we synthesize research from community psychology on community change and prevention with more individually focused studies of sexual violence prevention programs and bystander behavior in emergency and crime situations. The purpose of bringing together this research is to outline a new area of focus for sexual violence prevention: the mobilization of prosocial behavior on the part of potential bystanders. This approach has utility for increasing community receptivity to prevention messages, by decreasing resistance to them, and for increasing the likelihood of community members taking an active role in prevention and intervention. The specific case of sexual violence prevention on college campus communities illustrates this approach. © 2004 Wiley Periodicals, Inc. J Comm Psychol 32: 61–79, 2004.

Thawing sub-arctic permafrost - effects on vegetation and methane emissions

Abstract: Ecosystems along the 0degreesC mean annual isotherm are arguably among the most sensitive to changing climate and mires in these regions emit significant amounts of the important greenhouse gas methane (CH4) to the atmosphere. These CH4 emissions are intimately related to temperature and hydrology, and alterations in permafrost coverage, which affect both of those, could have dramatic impacts on the emissions. Using a variety of data and information sources from the same region in subarctic Sweden we show that mire ecosystems are subject to dramatic recent changes in the distribution of permafrost and vegetation. These changes are most likely caused by a warming, which has been observed during recent decades. A detailed study of one mire show that the permafrost and vegetation changes have been associated with increases in landscape scale CH4 emissions in the range of 22-66% over the period 1970 to 2000.

Large fluctuations in speed on Greenland's Jakobshavn Isbræ glacier

Abstract: It is important to understand recent changes in the velocity of Greenland glaciers because the mass balance of the Greenland Ice Sheet is partly determined by the flow rates of these outlets. Jakobshavn Isbrae is Greenland's largest outlet glacier, draining about 6.5 per cent of the ice-sheet area, and it has been surveyed repeatedly since 1991 (ref. 2). Here we use remote sensing data to measure the velocity of Jakobshavn Isbrae between 1992 and 2003. We detect large variability of the velocity over time, including a slowing down from 6,700 m yr(-1) in 1985 to 5,700 m yr(-1) in 1992, and a subsequent speeding up to 9,400 m yr(-1) by 2000 and 12,600 m yr(-1) in 2003. These changes are consistent with earlier evidence for thickening of the glacier in the early 1990s and rapid thinning thereafter. Our observations indicate that fast-flowing glaciers can significantly alter ice discharge at sub-decadal timescales, with at least a potential to respond rapidly to a changing climate.

Comparative in Vivo Stability of Copper-64-Labeled Cross-Bridged and Conventional Tetraazamacrocyclic Complexes

Abstract: The increased use of copper radioisotopes in radiopharmaceutical applications has created a need for bifunctional chelators (BFCs) that form stable radiocopper complexes and allow covalent attachment to biological molecules. The chelators most commonly utilized for labeling copper radionuclides to biomolecules are analogues of 1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetraacetic acid (TETA); however, recent reports have communicated the instability of the radio-Cu(II)-TETA complexes in vivo. A class of bicyclic tetraazamacrocycles, the ethylene "cross-bridged" cyclam (CB-cyclam) derivatives, form highly kinetically stable complexes with Cu(II) and therefore may be less susceptible to transchelation than their nonbridged analogues in vivo. Herein we report results on the relative biological stabilities and identification of the resulting radiolabeled metabolites of a series of (64)Cu-labeled macrocyclic complexes. Metabolism studies in normal rat liver have revealed that the (64)Cu complex of 4,11-bis(carboxymethyl)-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane ((64)Cu-CB-TE2A) resulted in significantly lower values of protein-associated (64)Cu than (64)Cu-TETA [13 +/- 6% vs 75 +/- 9% at 4 h]. A similar trend was observed for the corresponding cyclen derivatives, with the (64)Cu complex of 4,10-bis(carboxymethyl)-1,4,7,10-tetraazabicyclo[5.5.2]tetradecane ((64)Cu-CB-DO2A) undergoing less transchelation than the (64)Cu complex of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid ((64)Cu-DOTA) [61 +/- 14% vs 90.3 +/- 0.5% protein associated (64)Cu at 4 h]. These data indicate that the structurally reinforcing cross-bridge enhances in vivo stability by reducing metal loss to protein in both the cyclam and cyclen cross-bridged (64)Cu complexes and that (64)Cu-CB-TE2A is superior to (64)Cu-CB-DO2A in that regard. These findings further suggest that a bifunctional chelator derivative of CB-TE2A is a highly desirable alternative for labeling copper radionuclides to biological molecules for diagnostic imaging and targeted radiotherapy.

Discovery of Symbiotic Nitrogen-Fixing Cyanobacteria in Corals

Abstract: Colonies of the Caribbean coral Montastraea cavernosa exhibit a solar-stimulated orange-red fluorescence that is spectrally similar to a variety of fluorescent proteins expressed by corals. The source of this fluorescence is phycoerythrin in unicellular, nonheterocystis, symbiotic cyanobacteria within the host cells of the coral. The cyanobacteria coexist with the symbiotic dinoflagellates (zooxanthellae) of the coral and express the nitrogen-fixing enzyme nitrogenase. The presence of this prokaryotic symbiont in a nitrogen-limited zooxanthellate coral suggests that nitrogen fixation may be an important source of this limiting element for the symbiotic association.

Exposure to solar radiation increases damage to both host tissues and algal symbionts of corals during thermal stress

Abstract: Elevated seawater temperatures have long been accepted as the principal stressor causing the loss of symbiotic algae in corals and other invertebrates with algal symbionts (i.e., “bleaching”). A secondary factor associated with coral bleaching is solar irradiance, both its visible (PAR: 400–700 nm) and ultraviolet (UVR: 290–400 nm) portions of the spectrum. Here we examined the synergistic role of solar radiation on thermally induced stress and subsequent bleaching in a common Caribbean coral, Montastraea faveolata. Active fluorescent measurements show that steady-state quantum yields of photosystem II (PSII) fluorescence in the zooxanthellae are markedly depressed when exposed to high solar radiation and elevated temperatures, and the concentration of D1 protein is significantly lower in high light when compared to low light treatments under the same thermal stress. Both photosynthetic pigments and mycosporine-like amino acids (MAAs) are also depressed after experimental exposure to high solar radiation and thermal stress. Host DNA damage is exacerbated under high light conditions and is correlated with the expression of the cell cycle gene p 53, a cellular gatekeeper that modulates the fate of damaged cells between DNA repair processes and apoptotic pathways. These markers of cellular stress in the host and zooxanthellae have in common their response to the enhanced production of reactive oxygen species during exposure to high irradiances of solar radiation and elevated temperatures. Taking these results and previously published data into consideration, we conclude that thermal stress during exposure to high irradiances of solar radiation, or irradiances higher than the current photoacclimatization state, causes damage to both photochemistry and carbon fixation at the same time in zooxanthellae, while DNA damage, apoptosis, or necrosis are occurring in the host tissues of symbiotic cnidarians.

Intramolecular, compound‐specific, and bulk carbon isotope patterns in C3 and C4 plants: a review and synthesis

Abstract: Studies using carbon isotope differences between C3 and C4 photosynthesis to calculate terrestrial productivity or soil carbon turnover assume that intramolecular isotopic patterns and isotopic shifts between specific plant components are similar in C3 and C4 plants. To test these assumptions, we calculated isotopic differences in studies measuring components from C3 or C4 photosynthesis. Relative to source sugars in fermentation, C3 -derived ethanol had less 13 C and C3 -derived CO2 had more 13 C than C4 -derived ethanol and CO2 . Both results agreed with intramolecular isotopic signatures in C3 and C4 glucose. Isotopic shifts between plant compounds (e.g. lignin and cellulose) or tissues (e.g. leaves and roots) also differed in C3 and C4 plants. Woody C3 plants allocated more carbon to 13 C-depleted compounds such as lignin or lipids than herbaceous C3 or C4 plants. This allocation influenced 13 C patterns among compounds and tissues. Photorespiration and isotopic fractionation at metabolic branch points, coupled to different allocation patterns during metabolism for C3 vs C4 plants, probably influence position-specific and compound-specific isotopic differences. Differing 13 C content of mobile and immobile compounds (e.g. sugars vs lignin) may then create isotopic differences among plant pools and along transport pathways. We conclude that a few basic mechanisms can explain intramolecular, compound-specific and bulk isotopic differences between C3 and C4 plants. Understanding these mechanisms will improve our ability to link bulk and compound-specific isotopic patterns to metabolic pathways in C3 and C4 plants. Contents Summary 371 I. Introduction 372 II. Methods and terminology 373 III. Results 373 IV. Discussion 376 V. Conclusions 382 Acknowledgements 382 References 382.

Uncertainties in Precipitation and Their Impacts on Runoff Estimates

Abstract: Water balance calculations are becoming increasingly important for earth-system studies. Precipitation is one of the most critical input variables for such calculations because it is the immediate source of water for the land surface hydrological budget. Numerous precipitation datasets have been developed in the last two decades, but these datasets often show marked differences in their spatial and temporal distribution of this key hydrological variable. This paper compares six monthly precipitation datasets—Climate Research Unit of University of East Anglia (CRU), Willmott‐Matsuura (WM), Global Precipitation Climate Center (GPCC), Global Precipitation Climatology Project (GPCP), Tropical Rainfall Measuring Mission (TRMM), and NCEP‐Department of Energy (DOE) Atmospheric Model Intercomparison Project (AMIP-II) Reanalysis (NCEP-2)—to assess the uncertainties in these datasets and their impact on the terrestrial water balance. The six datasets tested in the present paper were climatologically averaged and compared by calculating various statistics of the differences. The climatologically averaged monthly precipitation estimates were applied as inputs to a water balance model to estimate runoff and the uncertainties in runoff arising directly from the precipitation estimates. The results of this study highlight the need for accurate precipitation inputs for water balance calculations. These results also demonstrate the need to improve precipitation estimates in arid and semiarid regions, where slight changes in precipitation can result in dramatic changes in the runoff response due to the nonlinearity of the runoff-generation processes.

Spatial and temporal variability in forest–atmosphere CO2 exchange

Abstract: Seven years of carbon dioxide flux measurements indicate that a ~ 90-year-old spruce dominated forest in Maine, USA, has been sequestering 174±46 gCm-2 yr-1 (mean±1 standard deviation, nocturnal friction velocity (u*) threshold >0.25ms-1). An analysis of monthly flux anomalies showed that above-average spring and fall temperatures were significantly correlated with greater monthly C uptake while above-average summer temperatures were correlated with decreased net C uptake. Summer months with significantly drier or wetter soils than normal were also characterized by lower rates of C uptake. Years with above-average C storage were thus typically characterized by warmer than average spring and fall temperatures and adequate summer soil moisture.

Cross-Cultural Reliability and Validity of the Revised Conflict Tactics Scales: A Study of University Student Dating Couples in 17 Nations

Abstract: Although the original Conflict Tactics Scales (CTS) have been successfully used in many countries, no studies have been published on the cross-cultural reliability and validity of the revised instrument (CTS2). This study is intended to provide some of the needed psychometric information. It reports reliability and examples of validity evidence for the five CTS2 (physical assault, physical injury, psychological aggression, sexual coercion, and negotiation) to measure these aspects of the dating relationships of 7,179 students at 33 universities in 17 countries. The results show high alpha coefficients of internal consistency and low confounding with social desirability response set. Examples indicating the construct validity of the CTS2 Physical Assault and Injury Scales are also presented. Although the data refer to dating relationships of university students, the results are sufficiently promising to encourage use of the CTS2 in a variety of cultural settings.

High mutation rate and predominance of insertions in the Caenorhabditis elegans nuclear genome

Abstract: Mutations have pivotal functions in the onset of genetic diseases and are the fundamental substrate for evolution. However, present estimates of the spontaneous mutation rate and spectrum are derived from indirect and biased measurements. For instance, mutation rate estimates for Caenorhabditis elegans are extrapolated from observations on a few genetic loci with visible phenotypes and vary over an order of magnitude1. Alternative approaches in mammals, relying on phylogenetic comparisons of pseudogene loci2 and fourfold degenerate codon positions3, suffer from uncertainties in the actual number of generations separating the compared species and the inability to exclude biases associated with natural selection. Here we provide a direct and unbiased estimate of the nuclear mutation rate and its molecular spectrum with a set of C. elegans mutation-accumulation lines that reveal a mutation rate about tenfold higher than previous indirect estimates and an excess of insertions over deletions. Because deletions dominate patterns of C. elegans pseudogene variation4,5, our observations indicate that natural selection might be significant in promoting small genome size, and challenge the prevalent assumption that pseudogene divergence accurately reflects the spontaneous mutation spectrum.

A model of cultural differences and international alliance performance

Abstract: We propose a model of cultural differences and international alliance performance to explain the ambiguous findings regarding the influence of national culture differences on alliance performance. Building on research on national, organizational, and professional cultures, we argue that the closer the domain of a social group is to the value-creating activities of an alliance, the more disruptive cultural differences between the partners’ members of that social group will be. Organizational culture differences will tend to be more disruptive than national culture differences, and differences in the professional culture most relevant to alliance value creation typically will be the most disruptive. Implications for research and managerial practice are discussed, and the model's relevance for international R&D alliances is highlighted.