bluuebunny/crossref_metadata_2025 huggingface dataset:
A MODEL OF UNIVERSAL TEICHMÜLLER SPACE AND ITS APPLICATION
Authors: KANG YUEMING , CHENG TAO , CHEN JIXIU
Published: February 2008

In this paper, one model of the universal Teichmüller space is studied. By the method of construction, the lower bound of the inner radius of univalency by the Pre-Schwarzian derivative of quasidisks with infinity as an inner point (such as domains bounded by ellipses) is obtained.
SCHUR MULTIPLICATIVE MAPS ON MATRICES
Authors: CLARK SEAN , LI CHI-KWONG , RASTOGI ASHWIN
Published: February 2008

The structure of Schur multiplicative maps on matrices over a field is studied. The result is then used to characterize Schur multiplicative maps f satisfying $f(S) \subseteq S$ for different subsets S of matrices including the set of rank k matrices, the set of singular matrices, and the set of invertible matrices. Characterizations are also obtained for maps on matrices such that Γ(f(A))=Γ(A) for various functions Γ including the rank function, the determinant function, and the elementary symmetric functions of the eigenvalues. These results include analogs of the theorems of Frobenius and Dieudonné on linear maps preserving the determinant functions and linear maps preserving the set of singular matrices, respectively.
Breastfeeding rates and duration in Germany: a Bavarian cohort study
Authors: Kohlhuber Martina , Rebhan Barbara , Schwegler Ursula , Koletzko Berthold , Fromme Hermann
Published: February 2008

Breastfeeding is the recommended feeding for all healthy infants. The aim of our study was to assess the current state of breastfeeding prevalence, duration and behaviour in Bavaria, Germany as a basis for targeting breastfeeding promotion measures. The Bavarian Breastfeeding Study is a prospective cohort study of 3822 mothers who delivered in April 2005 in Bavaria, Germany. Breastfeeding duration and determinants such as socioeconomic status, attitudes towards breastfeeding, birth mode and breastfeeding problems were assessed by questionnaires 2–6 d after birth and 2, 4, 6, and 9 months after birth. The initial breastfeeding rate was 90 %. After 4 months 61 % still breastfed (any breastfeeding). In the multivariate analyses the main influencing factor reducing breastfeeding initiation was the partner's negative attitude towards breastfeeding (OR 21·79; 95 % CI 13·46, 35·27). No initial breastfeeding was also associated with lower education, maternal grandmother's negative attitude and pre-term birth. Protective factors were primary breastfeeding experience and information on breastfeeding before birth. Breastfeeding duration < 4 months was strongly associated with breastfeeding problems (OR 7·56; 95 % CI 6·21, 9·19), smoking, lower education, partner's negative attitude and Caesarean section. Since the attitude of family members is an important influencing factor on breastfeeding rates, breastfeeding promotion should also target the partners of pregnant women and the families of newborn infants. Public health interventions such as more effective support for the management of breastfeeding problems, especially in lower social status families, should be implemented and their effectiveness should be critically evaluated.
Influence of host size variation on the development of a koinobiont aphid parasitoid,Lysiphlebus ambiguusHaliday (Braconidae, Hymenoptera)
Authors: Xu Q. , Meng L. , Li B. , Mills N.
Published: February 2008

To determine whether host body size is the currency used by the aphidiine parasitoid,Lysiphlebus ambiguus Haliday (Hymenoptera: Braconidae), in assessing host quality, the aphid,Aphis fabaeScopoli (Homoptera: Aphididae), was reared at either high or low temperature to yield hosts of the same instar with different body sizes. Cohorts ofA. fabae raised at 15°C and 30°C and exposed to individual femaleL. ambiguusin no-choice tests were successfully parasitized in all host stages from 1st instar nymphs to adults. However, younger and smaller aphids were more susceptible to parasitism than older and larger nymphs or adults, as measured by the number of mummies produced. For aphid cohorts reared at 15°C, the proportion of female progeny, progeny adult size, and development time all increased linearly with aphid size at the time of attack. In contrast, for aphid cohorts raised at 30°C, the proportion of female progeny and progeny adult size declined with aphid size, while development time remained unaffected. Through manipulation of host rearing temperature, we have shown that at cooler temperatures the koinobiont parasitoid,L. ambiguus, responds to host size in the same way as an idiobiont parasitoid, but that this response is compromised at higher temperatures. Our results suggest that differential mortality during development is likely to influence the observed secondary sex ratio in relation to aphid size for aphid cohorts raised at higher temperatures due to disruption of the activity of the host's primary endosymbiont and that such reduced nutritional quality of aphids cannot be compensated by increased development time.
Direct numerical simulation of passive scalar transport in transverse jets
Authors: MUPPIDI SUMAN , MAHESH KRISHNAN
Published: February 2008

Direct numerical simulation is used to study passive scalar transport and mixing in a round turbulent jet, in a laminar crossflow. The ratio of the jet velocity to that of the crossflow is 5.7, the Schmidt number of the scalar is 1.49, and the jet-exit Reynolds number is 5000. The scalar field is used to compute entrainment of the crossflow fluid by the jet. It is shown that the bulk of this entrainment occurs on the downstream side of the jet. Also, the transverse jet entrains more fluid than a regular jet even when the jet has not yet bent into the crossflow. The transverse jet's enhanced entrainment is explained in terms of the pressure field around the jet. The acceleration imposed by the crossflow deforms the jet cross-section on the downstream side, which sets up a pressure gradient that drives downstream crossflow fluid toward the jet. The simulation results are used to comment on the applicability of the gradient–diffusion hypothesis to compute passive scalar mixing in this flow field. Computed values of the eddy diffusivity show significant scatter, and a pronounced anisotropy. The near field also exhibits counter gradient diffusion.
Evidence of higher-order effects in thermally driven rapid granular flows
Authors: HRENYA C. M. , GALVIN J. E. , WILDMAN R. D.
Published: February 2008

Molecular dynamic (MD) simulations are used to probe the ability of Navier–Stokes-order theories to predict each of the constitutive quantities – heat flux, stress tensor and dissipation rate – associated with granular materials. The system under investigation is bounded by two opposite walls of set granular temperature and is characterized by zero mean flow. The comparisons between MD and theory provide evidence of higher-order effects in each of the constitutive quantities. Furthermore, the size of these effects is roughly one order of magnitude greater, on a percentage basis, for heat flux than it is for stress or dissipation rate. For the case of heat flux, these effects are attributed to super-Burnett-order contributions (third order in gradients) or greater, since Burnett-order contributions to the heat flux do not exist. Finally, for the system considered, these higher-order contributions to the heat flux outweigh the first-order contribution arising from a gradient in concentration (i.e. the Dufour effect)
Direct numerical simulations of rotating turbulent channel flow
Authors: GRUNDESTAM OLOF , WALLIN STEFAN , JOHANSSON ARNE V.
Published: February 2008

Fully developed rotating turbulent channel flow has been studied, through direct numerical simulations, for the complete range of rotation numbers for which the flow is turbulent. The present investigation suggests that complete flow laminarization occurs at a rotation number Ro = 2Ωδ/Ub ≤ 3.0, where Ω denotes the system rotation, Ub is the mean bulk velocity and δ is the half-width of the channel. Simulations were performed for ten different rotation numbers in the range 0.98 to 2.49 and complemented with earlier simulations (done in our group) for lower values of Ro. The friction Reynolds number Reτ = uτδ/ν (where uτ is the wall-shear velocity and ν is the kinematic viscosity) was chosen as 180 for these simulations. A striking feature of rotating channel flow is the division into a turbulent (unstable) and an almost laminarized (stable) side. The relatively distinct interface between these two regions was found to be maintained by a balance where negative turbulence production plays an important role. The maximum difference in wall-shear stress between the two sides was found to occur for a rotation number of about 0.5. The bulk flow was found to monotonically increase with increasing rotation number and reach a value (for Reτ = 180) at the laminar limit (Ro = 3.0) four times that of the non-rotating case.
Free-Lagrange simulations of the expansion and jetting collapse of air bubbles in water
Authors: TURANGAN C. K. , JAMALUDDIN A. R. , BALL G. J. , LEIGHTON T. G.
Published: February 2008

A free-Lagrange numerical method is implemented to simulate the axisymmetric jetting collapse of air bubbles in water. This is performed for both lithotripter shock-induced collapses of initially stable bubbles, and for free-running cases where the bubble initially contains an overpressure. The code is validated using two test problems (shock-induced bubble collapse using a step shock, and shock–water column interaction) and the results are compared to numerical and experimental results. For the free-running cases, simulations are conducted for a bubble of initial radius 0.3 mm located near a rigid boundary and near an aluminium layer (planar and notched surfaces). The simulations suggest that the boundary and its distance from the bubble influence the flow dynamics, inducing bubble elongation and jetting. They also indicate stress concentration in the aluminium and the likelihood of aluminium deformation associated with bubble collapse events. For the shock-induced collapse, a lithotripter shock, consisting of 56 MPa compressive and −10 MPa tensile waves, interacts with a bubble of initial radius 0.04 mm located in a free field (case 1) and near a rigid boundary (case 2). The interaction of the shock with the bubble causes it to involute and a liquid jet is formed that achieves a velocity exceeding 1.2 km s−1for case 1 and 2.6 km s−1for case 2. The impact of the jet on the downstream wall of the bubble generates a blast wave with peak overpressure exceeding 1 GPa and 1.75 GPa for cases 1 and 2, respectively. The results show that the simulation technique retains sharply resolved gas/liquid interfaces regardless of the degree of geometric deformation, and reveal details of the dynamics of bubble collapse. The effects of compressibility are included for both liquid and gas phases, whereas stress distributions can be predicted within elastic–plastic solid surfaces (both planar and notched) in proximity to cavitation events. There is a movie with the online version of the paper.
Landslide tsunamis propagating along a plane beach
Authors: SAMMARCO P. , RENZI E.
Published: February 2008

A forced two-horizontal-dimension analytical model is developed to investigate the distinguishing physical features of landslide-induced tsunamis generated and propagating on a plane beach. The analytical solution is employed to study the wave field at small times after the landslide motion starts. At larger times, the occurrence of transient edge waves travelling along the shoreline is demonstrated, showing the differences with the transient waves propagating over a bottom of constant depth. Results are satisfactorily compared with available experimental data. Finally, the validity of non-forced numerical models is discussed.
The initial-value problem for three-dimensional disturbances in plane Poiseuille flow of helium II
Authors: BERGSTRÖM LARS B.
Published: February 2008

The time development of small three-dimensional disturbances in plane Poiseuille flow of helium II is considered. The study is conducted by considering the interaction of a normal fluid field and a superfluid field. The interaction is caused by a mutual friction forcing between the two flow fields. Specifically, the stability of the normal fluid affected by the mutual forcing is considered. Compared to the ordinary fluid case where the mutual forcing is not present, the presence of the mutual forcing implies a substantial increase of the transient growth of the disturbances. The increase of the transient growth occurs because the mutual forcing reduces the damping of the disturbances. The phase of transient growth becomes thereby more prolonged and higher levels of amplification are reached. There is also a minor effect on the transient growth caused by the modification of the mean flow owing to the mutual forcing. The strongest transient growth occurs for streamwise elongated disturbances, i.e. disturbances with streamwise wavenumber α = 0. When α increases beyond zero, the transient amplification quickly becomes reduced. Striking differences compared to the ordinary fluid case are that the largest transient amplification does not occur when the spanwise wavenumber (β) is close to two and that the peak level of the disturbance energy density amplification does not depend on the square of the Reynolds number.
Recurrent solutions of Alber's equation for random water-wave fields
Authors: STIASSNIE M. , REGEV A. , AGNON Y.
Published: February 2008

The study addresses the linear instability of narrow spectra homogeneous seas and its subsequent evolution in time, subject to inhomogeneous disturbances. Specifically, we study unidirectional spectra, where according to the kinetic equation no spectral evolution is expected. In the region of instability, recurrent evolution is discovered. This recurrence is the stochastic counterpart of the Fermi–Pasta–Ulam recurrence obtained for the cubic Schrödinger equation.
Multidimensionality and intra-individual variation in host manipulation by an acanthocephalan
Authors: BENESH D. P. , VALTONEN E. T. , SEPPÄLÄ O.
Published: February 2008

Trophically-transmitted parasites frequently alter multiple aspects of their host's phenotype. Correlations between modified characteristics may suggest how different traits are mechanistically related, but these potential relationships remain unexplored. We recorded 5 traits from individual isopods infected with an acanthocephalan (Acanthocephalus lucii): hiding, activity, substrate colour preference, body (pereon) coloration, and abdominal (pleon) coloration. Infected isopods hid less and had darker abdominal coloration than uninfected isopods. However, in 3 different experiments measuring hiding behaviour (time-scales of observation: 1 h, 8 h, 8 weeks), these two modified traits were not correlated, suggesting they may arise via independent mechanisms. For the shorter experiments (1 h and 8 h), confidence in this null correlation was undermined by low experimental repeatability, i.e. individuals did not behave similarly in repeated trials of the experiment. However, in the 8-week experiment, hiding behaviour was relatively consistent within individuals, so the null correlation at this scale indicates, less equivocally, that hiding and coloration are unrelated. Furthermore, the difference between the hiding behaviour of infected and uninfected isopods varied over 8 weeks, suggesting that the effect ofA. luciiinfection on host behaviour changes over time. We emphasize the importance of carefully designed protocols for investigating multidimensionality in host manipulation.
Asymptotic density in quasi-logarithmic additive number systems
Authors: NIETLISPACH BRUNO
Published: February 2008

We show that in quasi-logarithmic additive number systems$\mycal{A}$all partition sets have asymptotic density, and we obtain a corresponding monadic second-order limit law for adequate classes of relational structures. Our conditions on the local counting functionp(n) of the set of irreducible elements of$\mycal{A}$allow situations which are not covered by the density theorems of Compton [6] and Woods [15]. We also give conditions onp(n) which are sufficient to show the assumptions of Compton's result are satisfied, but which are not necessarily implied by those of Bell and Burris [2], Granovsky and Stark [8] or Stark [14].
Salmonella infections associated with mung bean sprouts: epidemiological and environmental investigations
Authors: MOHLE-BOETANI J. C. , FARRAR J. , BRADLEY P. , BARAK J. D. , MILLER M. , MANDRELL R. , MEAD P. , KEENE W. E. , CUMMINGS K. , ABBOTT S. , WERNER S. B. ,   for the Investigation Team
Published: February 2008

We investigated an outbreak of Salmonella Enteritidis (SE) infections linked to raw mung bean sprouts in 2000 with two case-control studies and reviewed six similar outbreaks that occurred in 2000–2002. All outbreaks were due to unusual phage types (PT) of SE and occurred in the United States (PT 33, 1, and 913), Canada (PT 11b and 913), and The Netherlands (PT 4b). PT 33 was in the spent irrigation water and a drain from one sprout grower. None of the growers disinfected seeds at recommended concentrations. Only two growers tested spent irrigation water; neither discarded the implicated seed lots after receiving a report of Salmonella contamination. We found no difference in the growth of SE and Salmonella Newport on mung beans. Mung bean sprout growers should disinfect seeds, test spent irrigation water, and discontinue the use of implicated seed lots when pathogens are found. Laboratories should report confirmed positive Salmonella results from sprout growers to public health authorities.
Italy’s Readiness for the 1998 Euro in View of the Country’s Declining Competitiveness
Authors: Mascitelli Bruno , Gerstman Julie
Published: February 2008

In the 2006 Italian election campaign, then Prime Minister Silvio Berlusconi popularised a widely held view about the negative role of the euro for the Italian economy. This view had initially originated with the secessionist Northern Leagues. More recently, it had come to reflect the view of more moderate political players too. In the campaign Berlusconi ridiculed his contender, and the ultimate victor of the elections, Romano Prodi, for having accepted the ‘unfair Lira pegging’ to the euro in 1998. These claims reflect an ongoing debate about whether the adoption of the euro caused or even significantly contributed to Italy’s loss of economic competitiveness. We will trace the Italian trajectory and its economic preparedness for proposed entry into the EMU. We will weigh whether the terms and conditions of entry predisposed Italy to an inferior economic performance from the outset. We will assess the relative merits of the two interpretations of the role of the euro for Italy since its endorsement of the Maastricht Criteria, agreed to in December 1991. We will also look at the role played by the economic adjustments involved, followed soon after by Italy’s financial crisis in 1992. These latter events ultimately forced Italy to temporarily leave the European Monetary System (EMS). The country re-entered the EMS in 1998. We conclude that Italy’s weaknesses became more obvious with the adherence to conditions required for euro entry, but that its deep-seated political and economic problems were entrenched.
The Focus on Everyday Life: a New Turn in Sociology
Authors: Sztompka Piotr
Published: February 2008

Sociology is currently undergoing an interesting theoretical and methodological turn. A number of recent and influential works of sociology deal with the seemingly trivial phenomena of everyday life. The standard mass surveys are being replaced by in-depth, interpretative, and qualitative procedures that focus on the visual surface of society. They do so by means of observation and its extension – photography. The author believes that this is not a new fashion but rather signals a true paradigmatic shift. For the author, it heralds the emergence of a ‘third’ sociology, after the ‘first sociology’ of social organisms and systems, and the ‘second sociology’ of behaviour and action. The new focus is on social existence manifested by social events of various scales. This sociology of social existence provides a new angle of vision, which promises to advance considerably our understanding of several perennial riddles of human society.
French Enthusiasm for Solidarność
Authors: Frybes Marcin
Published: February 2008

France was one of the main supporters of Solidarność. The events in August and September 1980 immediately gained the interest of the French media. Trade unionists started to collaborate with their Polish colleagues, for instance by setting up exchange programs or by introducing Solidarność to international trade unions. Organisations of solidarity were founded and started to collect food, clothes and drugs. After the proclamation of Martial Law in Poland, this grew into a mass movement, involving many layers of the French population. Both workers and intellectuals were drawn to the idea of a ‘second left’: an alternative to the old and radical socialism.
Solidarność, Western Solidarity and Détente: A Transnational Approach
Authors: Berger Stefan
Published: February 2008

The reaction of Western trade unions towards Solidarność was extremely varied, ranging from enthusiastic support to the denunciation of Solidarność as ‘counter-revolutionary’ and in the pay of the CIA. These views depended on political, institutional, and cultural determinants and had much to do with the national circumstances of particular unions and their representatives.
Jews and Muslims in Dante’s Vision
Authors: Hede Jesper
Published: February 2008

Dante’s attitude towards Jews and Muslims in the Divine Comedy has been a controversial issue in literary studies of the medieval period. This article outlines the most central questions in this regard and argues that the treatment of the issue has often been misleading due to exaggeration and overstatement. Dante has been seen, respectively, as a summarizer of medieval culture and mentalities, as a medieval intellectual who was more open for non-Christian influences than his fellow Christians, and as a highly prejudiced conservative. In considering the constituents of Dante’s worldview, the article that follows argues that Dante should rather be seen as a medieval Christian whose cultural horizon was limited, whose political theory of world government was narrowly focused on a specific problem within European Christendom, and whose vision of redemption, although complex and original in various respects, could not but embrace all human beings as either righteous or corrupted Christians.
The Friar and the Sultan: Francis of Assisi’s Mission to Egypt
Authors: Tolan John
Published: February 2008

In September, 1219, Francis of Assisi went to Egypt to preach to Sultan al-Malik al-Kâmil. Although we in fact know very little about this event, writers from the 13th century to the 20th have portrayed Francis alternatively as a new apostle preaching to the infidels, a scholastic theologian proving the truth of Christianity, a champion of the crusading ideal, a naive and quixotic wanderer, a crazed religious fanatic, or a medieval Gandhi preaching peace, love and understanding. This study of the varying depictions of this lapidary encounter throws into relief the changing fears and hopes that Muslim–Christian encounters have inspired in European writers over eight centuries.
Strategies to control Canada thistle (Cirsium arvense) under organic farming conditions
Authors: Lukashyk Pavel , Berg Martin , Köpke Ulrich
Published: February 2008

Three strategies for controllingCirsium arvenseincluding (i) repeated stubble tillage with subsequent forage crop cultivation, (ii) repeated mowing of a ryegrass–clover ley and (iii) forage crop cultivation following a ryegrass–clover ley ploughed in May/June were investigated in field experiments over 3 years at the Experimental Farm for Organic Agriculture ‘Wiesengut’ in North-Rhine Westphalia, Germany. The development ofC. arvense(shoot density, shoot size and ground cover) was regularly assessed on fixed standardized subplots. In the medium-term (9 months), repeated stubble tillage (i) decreased shoot density and regrowth capacity ofC. arvensemore effectively than a mowed ryegrass–clover ley (ii and iii). However, after 22 months, strategies (i) and (ii) resulted in a similar strong reduction ofC. arvenseshoot density of 95 and 97%, respectively. At this time, the efficacy of strategy (iii) (89%) was not significantly different to that of strategies (i) and (ii). After 26 months, the effect of all strategies was still apparent; however, the efficacy of strategy (iii) was significantly lower than that of strategy (ii). Generally, the different strategies showed only minor differences, thus delivering options for optimal strategies of thistle control under given specific conditions of sites and cropping systems.
Energy self-reliance, net-energy production and GHG emissions in Danish organic cash crop farms
Authors: Halberg N. , Dalgaard R. , Olesen J.E. , Dalgaard T.
Published: February 2008

Organic farming (OF) principles include the idea of reducing dependence of fossil fuels, but little has been achieved on this objective so far in Danish OF. Energy use and greenhouse gas (GHG) emissions from an average 39 ha cash crop farm were calculated and alternative crop rotations for bio-energy production were modeled. Growing rapeseed on 10% of the land could produce bio-diesel to replace 50–60% of the tractor diesel used on the farm. Increasing grass-clover area to 20% of the land and using half of this yield for biogas production could change the cash crop farm to a net energy producer, and reduce GHG emissions while reducing the overall output of products only marginally. Increasing grass-clover area would improve the nutrient management on the farm and eliminate dependence on conventional pig slurry if the biogas residues were returned to cash crop fields.
Tanniferous forage plants: Agronomic performance, palatability and efficacy against parasitic nematodes in sheep
Authors: Häring D.A. , Scharenberg A. , Heckendorn F. , Dohme F. , Lüscher A. , Maurer V. , Suter D. , Hertzberg H.
Published: February 2008

Tanniferous forage plants can have beneficial effects on ruminant productivity and health (improved protein supply, bloat safety and antiparasitic properties). However, condensed tannins can also lower palatability, voluntary feed intake and digestibility. The aim of our interdisciplinary project was to generate basic knowledge on plant management, feed palatability and the antiparasitic properties of tanniferous forage plants for their practical application in agronomy, focusing on their usefulness in controlling gastrointestinal nematodes in organic farming. We found thatOnobrychis viciifolia(sainfoin),Lotus corniculatus(birdsfoot trefoil) andCichorium intybus(chicory) were suitable for cultivation under the given temperate climatic conditions, whereasLotus pedunculatus(big trefoil) was soon outcompeted by unsown species. Growing the tanniferous plant species in a mixture withFestuca pratensis(meadow fescue) rather than in a monoculture had the advantage of increasing total dry matter (DM) yield (especially in the case of tanniferous legumes) and of reducing the DM proportions of unsown species. However, due to dilution by non-tanniferousF. pratensis, the tannin concentrations of mixtures were clearly lower and the seasonal fluctuations in tannin concentrations greater than that of monocultures. Across species, tannin concentrations were highest forO. viciifolia, followed byL. corniculatusand very low forC. intybus. Palatability of all tanniferous forages was comparable to that of a ryegrass/clover mixture when fed as dried forage and, when offered as silage, palatability ofO. viciifoliawas clearly superior to that of the respective ryegrass/clover control. Administration of dried or ensiledO. viciifoliareduced parasite egg counts in feces of lambs co-infected with the gastrointestinal nematode speciesHaemonchus contortusandCooperia curticei. We conclude thatO. viciifoliais the most promising among the tested tanniferous forage plant species due to its suitability for cultivation, its high tannin concentration, its high palatability and its antiparasitic activity even in dried or ensiled form.
Value in the values: pasture-raised livestock products offer opportunities for reconnecting producers and consumers
Authors: Conner David S. , Campbell-Arvai Victoria , Hamm Michael W.
Published: February 2008

Pasture-based livestock production holds promise in helping to reinvigorate small and mid-scale farming, as well as farm communities, across the United States. In this study, in-depth interviews of pasture-based livestock producers, meat processors and buyers were conducted to determine behaviors, attitudes and expectations with regard to pasture-based livestock production. In addition, consumers were polled to determine their attitudes with respect to how food animals are raised and treated. Results revealed many shared values between those involved in raising, processing and distributing animal products, as well as consumers, indicating an opportunity for a ‘re-embedding’ of livestock production based on these shared values. The concurrent development of both direct and extended markets, e.g. values-based value chains, is suggested as one way of addressing the difficulties faced by individual farmers in processing and distributing animal products with their provenance and underlying values intact.
Integrated crop/livestock systems research: Practical research considerations
Authors: Tanaka D.L. , Karn J.F. , Scholljegerdes E.J.
Published: February 2008

There are many reasons for the paucity of integrated crop/livestock research and associated publications. Integrated/crop livestock experiments that involve adequate treatments and replications, as perceived by both crop and animal scientists, require large numbers of hectares, many animals, considerable labor to conduct the research, substantial financial resources, and a commitment by Federal and State Research Agencies to fund such long-term research projects. To be truly integrated, crop/livestock research must be multidisciplinary, involving scientists of diverse training and experience with expertise to address various aspects of the research problem, and scientists must function as a cohesive unit or team. The prevailing attitude that all experimental data must be statistically analyzed to be of any value is also a detriment to integrated research. Statistical analyses of these projects may be quite challenging and require new or unusual approaches. Related to the prevailing need for statistical analysis is also the need for scientists to publish senior authored publications for career advancement. Conducting integrated research may not facilitate scientists' publishing the number and quality of publications required for them to meet these criteria. A further obstacle to integrated research alluded to above, involves the many experimental design compromises that must be made by cooperating scientists. Crop and soil scientists for example, use many treatments and replications with small plots, while animal scientists, by necessity, have experiments that involve relatively large numbers of hectares and animal numbers with relatively few treatments and replications. It is therefore extremely difficult to initiate such projects given these inherent differences in crop versus livestock research protocol, as well as to design effective experiments that will provide publishable data. Making compromises on the many factors relevant to integrated crop/livestock research while designing experiments that will provide solutions to pertinent producer problems as well as useful data that can be statistically analyzed and published is, therefore, extremely difficult.
History, current state, and future directions of ionospheric imaging
Authors: Bust Gary S. , Mitchell Cathryn N.
Published: February 2008

With the current data availability from both ground‐ and space‐based sources, the network of ground‐based Global Positioning System (GPS) receivers, GPS occultation receivers, in situ electron density sensors, and dual‐frequency beacon transmitters, the time is right for a comprehensive review of the history, current state, and future directions of ionospheric imaging. A brief introduction and history of ionospheric imaging is presented, beginning with computerized ionospheric tomography. Then, a comprehensive review of the current state of ionospheric imaging is presented. The ability of imaging algorithms to ingest multiple types of data and use advanced inverse techniques borrowed from meteorological data assimilation to produce four‐dimensional images of electron density is discussed. Particular emphasis is given to the mathematical basis for the different methods. The science that ionospheric imaging addresses is discussed, and the scientific contributions that ionospheric imaging has made are described. Finally, future directions for this research area are outlined.
Thresholds in the storm response of a catchment‐lake system and the occurrence and magnitude of lake overflows: Implications for flood frequency
Authors: Kusumastuti Dyah I. , Sivapalan Murugesu , Struthers Iain , Reynolds David A. , Murray Kevin , Turlach Berwin A.
Published: February 2008

This model‐based study examines the combined effects of catchment and lake thresholds upon the frequency and magnitude of lake‐overflow events, and their impacts on flood frequency. A dominant control of lake‐overflow events is antecedent storage, which is governed by the climate and by the properties of the contributing catchment. The next major control was shown to be the magnitude of storm depths, and their adequacy to replenish and exceed the lake storage deficit, which are governed by the ratio of catchment to lake areas, AC/AL. When AC/AL is large, lake‐overflows can be triggered even at larger antecedent lake storage deficits. This points to the importance of AC/AL as a critical parameter governing the frequency and magnitude of lake‐overflow events. As regards the catchment properties, model simulations indicate that fast draining catchments enhance the triggering of lake‐overflow events due to the fact that the drainage is rapid and there is the opportunity for faster runoff contributions to combine with direct rainfall on the lakes to exceed antecedent lake storage deficit and overcome the reducing influence of evaporation during inter‐storm periods. Slow draining catchments, on the other hand, will not release runoff fast enough to replenish the lake storage deficit before the evaporative effects take hold. The shape of the resulting flood frequency curve captures the dominant lake‐overflow generating mechanisms. When the dominant lake overflow generating mechanism is catchment runoff, the shape of flood frequency curve of lake‐overflows resembles the shape of the catchment flood frequency curve, including the effects of associated thresholds. On the other hand, when the dominant lake overflow generating mechanism is direct rainfall falling on the lake, the shape of the lake‐overflow flood frequency curve exhibits a persistent truncation below a critical return period that is associated with the frequency of flow termination for the given climate in question. These results have provided valuable insights into the relative roles of climate, soil depth, the soil's drainage capacity as well as the ratio of catchment area to lake area on flood frequency of catchment‐lake systems in general. The improved understanding of these process controls will be useful in assisting the management of such combined catchment‐lake systems. In particular, they can provide valuable guidance towards the monitoring of catchment‐lake systems in ways that are targeted towards those controls which are critical to the determination of the magnitude and frequency of lake‐overflow events to assist in flood prevention and mitigation.
Southwest Watershed Research Center Data Access Project
Authors: Nichols M. H. , Anson E.
Published: February 2008

Hydrologic data, including rainfall and runoff data, have been collected on experimental watersheds operated by the U.S. Department of Agriculture Agricultural Research Service (USDA‐ARS) in southern Arizona since the 1950s. These data are of national and international importance and make up one of the most comprehensive semiarid watershed data sets in the world. The USDA‐ARS Southwest Watershed Research Center has recently developed an electronic data processing system that includes an online interface (http://tucson.ars.ag.gov/dap) to provide public access to the data. The goal of the system is to promote analyses and interpretations of historic and current data by improving data access. Data are collected from sensors in the field and are transmitted to computers in the office. The data are then processed, quality checked, and made available to users via the Internet. The publicly accessible part of the system consists of an interactive Web site, which provides an interface to the data, and a relational database, which is used to process, store, and manage data. The system was released to the public in October 2003, and since that time the online data access Web site has received more than 4500 visitors.
Scaling laws and frequency distributions of avalanche areas in a self‐organized criticality model of solar flares
Authors: Morales Laura F. , Charbonneau Paul
Published: February 2008

We calculate the spreading exponents and some geometrical properties of avalanches in a novel avalanche model of solar flares, closely built on Parker's physical picture of coronal heating by nanoflares. The model is based on an idealized representation of a coronal loop as a bundle of magnetic flux strands wrapping around one another, numerically implemented as an anisotropic cellular automaton. We demonstrate that the growth of avalanches in this model exhibits power‐laws correlations that are numerically consistent with the behavior of a general class of statistical physical systems in the vicinity of a stationary critical point. This demonstrates that the model indeed operates in a self‐organized critical regime. Moreover, we find that the frequency distribution of avalanche peak areas A assumes a power‐law form f(A) ∝ with an index αA ≃ 2.45, in excellent agreement with observationally‐inferred values.
Modeling dense pyroclastic basal flows from collapsing columns
Authors: Doyle E. E. , Hogg A. J. , Mader H. M. , Sparks R. S. J.
Published: February 2008

A two layer model for the formation of dense pyroclastic basal flows from dilute, collapsing volcanic eruption columns is presented. The collapsing dilute current is described by depth averaged, isothermal, continuum conservation equations. The dense basal flow is modelled as a granular avalanche of constant density. Simulations demonstrate that pyroclastic flow formation and behavior is dependent upon slope conditions when the dilute part of the current has lost most of its mass. The dilute current runout increases with decreasing particle size and increasing initial column height. If the dilute current has transferred its mass to the dense basal flow on volcanic slopes with inclination angle greater than the friction angle of the basal flow, then the basal flow will continue to propagate until frictional forces bring it to rest. If the dilute current terminates on lower angled slopes, frictional forces dominate the basal flow preventing further front propagation.
Radar scatter from equatorial electrojet waves: An explanation for the constancy of the Type I Doppler shift with zenith angle
Authors: Kelley M. C. , Cuevas R. A. , Hysell D. L.
Published: February 2008

The first results from the 430 MHz Advanced Modular Incoherent Scatter Radar Prototype (AMISR‐P) at the Jicamarca Radio Observatory were reported by Hysell et al. (2007). We present additional data showing that the phase velocity of Type I echoes is independent of zenith angle, an unexplained property of these waves. We interpret the results using rocket data by predicting the total line‐of‐sight velocity at the four zenith angles used. We find that the radars preferentially detect waves within 10% of Cs in at least four range gates for all beams and up to eight range gates for the 51 JULIA beam. This result is consistent with recent auroral observations that Type I waves are only generated with k vectors near the electron flow velocity, where the latter is the vector sum of the zero‐order drift and the perturbation drift due to large‐scale waves in the equatorial case.
Planetary magnetic signature of the storm wind disturbance dynamo currents: Ddyn
Authors: Le Huy Minh , Amory‐Mazaudier Christine
Published: February 2008

During magnetic storms, Joule heating and ion drag, in auroral zones, strongly influence the circulation of thermospheric neutral winds. Joule heating produces equatorward neutral winds at F‐region heights with return flow at E‐region altitudes around the equator, the so‐called Hadley cell. The modified thermospheric circulation produces upwelling of molecule‐enriched air at high latitudes and global changes in the atmospheric composition. The equatorward neutral winds extending from the auroral zone to mid and low latitudes through the Coriolis force create westward storm wind which drives an equatorward dynamo current. In this paper, we detect for the first time, in the three longitude sectors, the planetary magnetic signature (Ddyn) of ionospheric disturbance dynamo with its main features: (1) the decrease of the equatorial electrojet due to a westward electric current flow opposite to the regular eastward current flow and (2) the equatorward ionospheric disturbance dynamo currents at midlatitudes.
Monte Carlo model of electron transport for the calculation of Mars dayglow emissions
Authors: Shematovich V. I. , Bisikalo D. V. , Gérard J.‐C. , Cox C. , Bougher S. W. , Leblanc F.
Published: February 2008

A model of the photoelectron collision‐induced component of the Mars dayglow using recent cross sections and solar flux is described. The calculation of the photoelectron source of excitation is based on a stochastic solution of the Boltzmann equation using the direct simulation Monte Carlo method. The neutral atmosphere is taken from outputs of a global circulation model, and recent inelastic collision cross sections are adopted. The calculated vertical profiles of the CO Cameron bands and CO2+ doublet emissions integrated along the line of sight compare well with the Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars (SPICAM) limb profiles observed with the SPICAM spectrograph on board Mars Express made at Ls = 166° during the summer season at northern midlatitudes. The comparison shows agreement to within the uncertainties of the excitation cross sections. Seasonal changes in the brightness and the altitude of the emission peaks are predicted with intensity variations in the range 15–20%.
Monitoring start of season in Alaska with GLOBE, AVHRR, and MODIS data
Authors: Robin Jessica , Dubayah Ralph , Sparrow Elena , Levine Elissa
Published: February 2008

This work evaluates whether continuity between Advanced Very High Resolution Radiometer (AVHRR) and Moderate Resolution Imaging Spectroradiometer (MODIS) normalized difference vegetation index (NDVI) is achievable for monitoring phenological changes in Alaska. This work also evaluates whether NDVI can detect changes in start of the growing season (SOS) in this region. Six quadratic regression models with NDVI as a function of accumulated growing degree days (AGDD) were developed from 2001 through 2004 AVHRR and MODIS NDVI data sets for urban, mixed, and forested land covers. Model parameters determined NDVI values for start of the observational period as well as peak and length of the growing season. NDVI values for start of the growing season were determined from the model equations and field observations of SOS made by GLOBE students and researchers at University of Alaska Fairbanks. AGDD was computed from daily air temperature. AVHRR and MODIS models were significantly different from one another with differences in the start of the observational season as well as start, peak, and length of the growing season. Furthermore, AGDD for SOS was significantly lower during the 1990s than the 1980s. NDVI values at SOS did not detect this change. There are limitations with using NDVI to monitor phenological changes in these regions because of snow, the large extent of conifers, and clouds, which restrict the composite period. In addition, differing processing and spectral characteristics restrict continuity between AVHRR and MODIS NDVI data sets.
Oxidative stress and α1‐adrenoceptor‐mediated stimulation of the Cl−/HCO3−exchanger in immortalized SHR proximal tubular epithelial cells
Authors: Simão S , Fraga S , Jose P A , Soares‐da‐Silva P
Published: February 2008

Background and purpose:

This study evaluated the signalling coupled to the α1‐adrenoceptor‐induced stimulation of the Cl−/HCO3−exchanger in hypertension.

Experimental approach:

The Na+‐independent HCO3−transport system activity was assayed as the initial rate of pHirecovery after an alkaline load (CO2/HCO3removal) in immortalized renal proximal tubular epithelial cells from spontaneously hypertensive rat (SHR) and their normotensive control (Wistar Kyoto rat; WKY).

Key results:

Noradrenaline increased Cl−/HCO3−exchanger activity with EC50values of 0.6 and 5.3 μMin SHR and WKY cells, respectively. These effects were abolished by prazosin, but not by yohimbine. Phenylephrine increased Cl−/HCO3−exchanger activity in SHR and WKY cells (EC50of 2.6 and 4.9 μM, respectively). Phenylephrine‐mediated increase in Cl−/HCO3−exchanger activity in WKY and SHR cells was inhibited by protein kinase C (PKC), MAPK/ERK kinase (MEK) and p38 mitogen‐activated protein kinase (p38 MAPK) inhibitors. The expression of α1A‐ and α1B‐adrenoceptors was identical in WKY and SHR cells. SHR cells generated more H2O2than WKY cells. In SHR cells, the NADPH oxidase inhibitor apocynin reduced their increased ability to generate H2O2and abolished their hypersensitivity to phenylephrine, but failed to affect basal Cl−/HCO3−exchanger activity. H2O2‐dependent stimulation of Cl−/HCO3−exchange activity was significantly higher in SHR than in WKY cells.

Conclusions and implications:

Differences between WKY and SHR cells on their sensitivity to α1‐adrenoceptor stimulation did not correlate with the abundance of α1A‐ and α1B‐adrenoceptors and may be related to the increased generation of H2O2, which may amplify the response downstream of α1‐adrenoceptor activation.

British Journal of Pharmacology(2008)153, 1445–1455; doi:10.1038/bjp.2008.16; published online 25 February 2008