bluuebunny/crossref_metadata_2025 huggingface dataset:
EXPONENTIAL STABILISATION OF A TREE-SHAPED NETWORK OF STRINGS WITH VARIABLE COEFFICIENTS
Authors: GUO YAN NI , XU GEN QI
Published: March 2011

In this paper, we deal with a tree-shaped network of strings with a fixed root node. By imposing velocity feedback controllers on all vertices except the root node, we show that the spectrum of the system operator consists of all isolated eigenvalues of finite multiplicity and is distributed in a strip parallel to the imaginary axis under certain conditions. Moreover, we prove that there exists a sequence of eigenvectors and generalised eigenvectors that forms a Riesz basis with parentheses, and that the imaginary axis is not an asymptote of the spectrum. Thereby, we deduce that the system is exponentially stable.
A DIOPHANTINE FROBENIUS PROBLEM RELATED TO RIEMANN SURFACES
Authors: O'SULLIVAN CORMAC , WEAVER ANTHONY
Published: March 2011

We obtain sharp upper and lower bounds on a certain four-dimensional Frobenius number determined by a prime pair (p, q), 2 < p < q, including exact formulae for two infinite subclasses of such pairs. Our work is motivated by the study of compact Riemann surfaces which can be realised as semi-regular pq-fold coverings of surfaces of lower genus. In this context, the Frobenius number is (up to an additive translation) the largest genus in which no surface is such a covering. In many cases it is also the largest genus in which no surface admits an automorphism of order pq. The general t-dimensional Frobenius problem (t ≥ 3) is NP-hard, and it may be that our restricted problem retains this property.
SIGN-CHANGING SOLUTIONS OF (e1, B)-LIMIT INCREASING OPERATOR EQUATION
Authors: XIAN XU
Published: March 2011

In this paper, by using the fixed point index method first we obtain some existence and multiplicity results for sign-changing solutions of an (e1, B)-limit increasing operator equation. The main results can be applied to many non-linear boundary value problems to obtain the existence and multiplicity results for sign-changing solutions. We also give a clear description of locations of these sign-changing solutions through strict lower and upper solutions. As an example, in the last section we obtain some existence and multiplicity results for sign-changing solutions of some Sturm–Liouville differential boundary value problems.
ON CLOSED GEODESICS IN THE LEAF SPACE OF SINGULAR RIEMANNIAN FOLIATIONS
Authors: ALEXANDRINO MARCOS M. , JAVALOYES MIGUEL ANGEL
Published: March 2011

In this paper we prove the existence of closed geodesics in the leaf space of some classes of singular Riemannian foliations (s.r.f.), namely s.r.fs. that admit sections or have no horizontal conjugate points. We also investigate the shortening process with respect to Riemannian foliations.
UNCONDITIONAL CONVERGENCE IN THE STRONG OPERATOR TOPOLOGY AND ℓ∞
Authors: GHENCIU IOANA , LEWIS PAUL
Published: March 2011

In this paper we study non-complemented spaces of operators and the embeddability of ℓ∞in the spaces of operatorsL(X,Y),K(X,Y) andKw*(X*,Y). Results of Bator and Lewis [2,3] (Bull. Pol. Acad. Sci. Math.50(4) (2002), 413–416;Bull. Pol. Acad. Sci. Math.549(1) (2006), 63–73), Emmanuele [8–10] (J. Funct. Anal.99(1991), 125–130;Math. Proc. Camb. Phil. Soc.111(1992), 331–335;Atti. Sem. Mat. Fis. Univ. Modena42(1) (1994), 123–133), Feder [11] (Canad. Math. Bull.25(1982), 78–81) and Kalton [16] (Math. Ann.208(1974), 267–278), are generalised. A vector measure result is used to study the complementation of the spacesW(X,Y) andK(X,Y) in the spaceL(X,Y), as well as the complementation ofK(X,Y) inW(X,Y). A fundamental result of Drewnowski [7] (Math. Proc. Camb. Phil. Soc.108 (1990), 523–526) is used to establish a result for operator-valued measures, from which we obtain as corollaries the Vitali–Hahn–Saks–Nikodym theorem, the Nikodym Boundedness theorem and a Banach space version of the Phillips Lemma.
ON FREE SPECTRA OF LOCALLY TESTABLE SEMIGROUP VARIETIES
Authors: DOLINKA IGOR
Published: March 2011

For each k ≥ 2, we determine the asymptotic behaviour of the sequence of cardinalities of finitely generated free objects in , the variety consisting of all k-testable semigroups.
Optimal stirring strategies for passive scalar mixing
Authors: LIN ZHI , THIFFEAULT JEAN-LUC , DOERING CHARLES R.
Published: March 2011

We address the challenge of optimal incompressible stirring to mix an initially inhomogeneous distribution of passive tracers. As a quantitative measure of mixing we adopt the H−1 norm of the scalar fluctuation field, equivalent to the (square root of the) variance of a low-pass filtered image of the tracer concentration field. First we establish that this is a useful gauge even in the absence of molecular diffusion: its vanishing as t → ∞ is evidence of the stirring flow's mixing properties in the sense of ergodic theory. Then we derive absolute limits on the total amount of mixing, as a function of time, on a periodic spatial domain with a prescribed instantaneous stirring energy or stirring power budget. We subsequently determine the flow field that instantaneously maximizes the decay of this mixing measure – when such a flow exists. When no such ‘steepest descent’ flow exists (a possible but non-generic situation), we determine the flow that maximizes the growth rate of the H−1 norm's decay rate. This local-in-time optimal stirring strategy is implemented numerically on a benchmark problem and compared to an optimal control approach using a restricted set of flows. Some significant challenges for analysis are outlined.
On the grammaticalization of personal pronouns
Authors: HEINE BERND , SONG KYUNG-AN
Published: March 2011

Unlike most other grammatical domains, that of personal pronouns is clearly under-researched in works on grammaticalization. One reason can be seen in the fact that personal pronouns differ in their diachronic behavior from most other grammatical categories to the extent that they present a challenge to grammaticalization theory. In the present paper it is argued that in order to account for this behavior, an extended understanding of grammaticalization is needed.
Association of vascular epiphytes with landscape units and phorophytes in humid lowland forests of Colombian Amazonia
Authors: Benavides A. M. , Vasco A. , Duque A. J. , Duivenvoorden J. F.
Published: March 2011

The species composition of vascular epiphytes and phorophytes (trees and lianas) was studied in ten 0.1-ha forest plots distributed over three landscape units (floodplains, swamps and well-drained uplands) in Colombian Amazonia. The aim was to analyse how host-preferences contributed to the patterns in epiphyte assemblages among the landscape units. In the plots 82 species (3310 plants) were holo-epiphytes, 11 species were primary hemi-epiphytes (179 plants) and 61 were secondary hemi-epiphytes (2337 plants). A total of 411 species of tree and liana were recorded as phorophytes. Detrended Correspondence Analysis and Mantel tests showed that the species composition of holo-epiphytes and secondary hemi-epiphytes differed among the landscape units. For both groups the effect of landscape unit on species composition strongly decreased after controlling for the phorophyte composition in the plots. The phorophyte composition significantly explained epiphyte composition and this effect was not removed after accounting for the effect of landscape unit. At the level of individual species, randomization tests yielded only few significant epiphyte–phorophyte associations. For 84% of the epiphyte species the average indicator of patchiness was below 1.5 demonstrating that most epiphyte individuals occurred scattered over different phorophytes. This probably hampered the analyses of host preferences for individual epiphyte species.
Is competition with livestock detrimental for native wild ungulates? A case study of chital (Axis axis) in Gir Forest, India
Authors: Dave Chittaranjan , Jhala Yadvendradev
Published: March 2011

Livestock graze Indian forests to varying extents but their impact on wild native ungulates is rarely understood. Negative impacts of sympatric livestock on chital (Axis axis) demography and food availability were assessed and compared in the Gir Forest, India, at different spatio-temporal scales. No difference in average group size (mean ± SE) (7.11 ± 0.8 indiv.) (short-term response), fawn to doe ratio (0.43 ± 0.03) (short- to medium-term response), chital density (44.8 ± 7.1 indiv. km−2) (medium- to long-term response), and rate of population increase (r= 0.07 ± 0.014) (long-term response) was found between areas sympatric and livestock-free at the larger spatial scale of Gir Forest. Instead, chital density was correlated with rainfall (r= 0.92). After controlling for confounding factors of rainfall, vegetation community, terrain and lion density, chital density was 62% higher for livestock-free compared with sympatric areas but other demographic parameters showed no statistical difference. Peak above-ground biomass was greater in livestock-free (3255 ± 209 kg ha−1) compared to sympatric areas (1438 ± 152 kg ha−1), but chital food was more abundant in moderately grazed areas compared to livestock-free areas. Overall, long-term livestock grazing has depressive effects on chital but in the short term habitat productivity and suitability overrides the depressive effects of sympatric livestock.
Origin of trunk damage in West African savanna trees: the interaction of fire and termites
Authors: N'Dri A. B. , Gignoux J. , Konaté S. , Dembélé A. , Aïdara D.
Published: March 2011

Two main types of hollow tree are frequently found in savannas: trees with external splits (externally damaged trees), and trees with no or little visible external damage, but with their entire core removed (internally damaged or ‘piped’ trees). As this may affect trunk mechanical resistance and tree survivorship, we studied the incidence of these two types of cavity in relation to two possible causal agents, fire and termites, in a West African savanna. Overall, the proportion of damaged adult trees (height >2 m) reached 36%, and up to 84% forCrossopteryx febrifuga. In this species, almost all (93%) damaged individuals showed signs of digging by fungus-grower and wood-feeder termites. External damage was more frequent in the more fire-prone shrubby savanna, suggesting that while termites are responsible for the piping, fire is responsible for the later opening of the trunk. Trees growing in the more fire-prone savanna tended to reach significantly smaller sizes, both in height and basal diameter, than in the less intensely burnt woody savanna. There was also evidence that piped trees were taller than externally damaged trees. This strongly suggests that fire causes an increased mortality of adult trees through lateral opening of the trunks causing later breakage.
Vertical stratification of Neotropical leaf-nosed bats (Chiroptera: Phyllostomidae) revealed by stable carbon isotopes
Authors: Rex Katja , Michener Robert , Kunz Thomas H. , Voigt Christian C.
Published: March 2011

Tropical rain forests harbour the most diverse plant and animal assemblages known to science, but our understanding of assemblage structure and species interactions is limited. Bats, as the only flying mammals, have the potential to exploit resources from all strata in forest communities. Thus, fruit-eating phyllostomid bats often have been categorized into canopy-, subcanopy- and understorey-foraging species, based largely upon the height at which they were most frequently captured. Here we challenge this classification and use stable carbon isotopes to assess foraging height of bat species at an Amazonian rain-forest site in Ecuador and at a Caribbean lowland rain-forest site in Costa Rica for comparison with data from mist-net captures. The proportion of the heavy stable carbon isotope13C in relation to the lighter12C isotope increases in plants from ground level to the canopy (0.12‰ m−1–0.18‰ m−1), and these differences in stable carbon isotope signatures are reflected in the body tissue of phytophagous bats. We used the stable carbon isotope ratio (δ13C) of wing tissue to estimate the foraging heights of 54 phyllostomid species in two Neotropical bat assemblages. Based on stable isotope data, phyllostomid species exploit food resources at all vertical strata of the forest. Capture height was not a reliable predictor of foraging height and suggests that bats most likely use lower strata to commute between foraging sites to avoid predators. Vertical stratification is likely to be a key factor promoting niche partitioning, thus promoting high local species richness in many tropical animal assemblages.
A Gram determinant for Lickorish's bilinear form
Authors: CAI XUANTING
Published: March 2011

We use the Jones–Wenzl idempotents to construct a basis of the Temperley–Lieb algebra TLn. This allows a short calculation for a Gram determinant of Lickorish's bilinear form on the Temperley–Lieb algebra.
Ecumenicalism Through Constitutionalism: The Discursive Development of Constitutional Conservatism inNational Review, 1955–1980
Authors: Kersch Ken I.
Published: March 2011

Contemporary conservatism places an affinity for, fidelity to, and defense of the U.S. Constitution at the center of its electoral, institutional, and movement politics. Through a survey of popular constitutional discourse in postwar conservatism's premiere magazine,National Reviewbetween 1955 and 1980—presented in the context of the development of (conservative) political thought and the institutional infrastructure for idea generation and propagation—I argue that that defense began to assume an ecumenically populist, antielitist, and antijudicial form only beginning in the mid-1950s, and a shared commitment to “originalism” only in the late 1970s. From the 1950s through the late 1970s, conservative constitutional argument was centered not on the judiciary, but rather on the (often divisive) constitutionalism of Congress and the executive, and on divergent views concerning structuralist versus moralist constitutional understandings. Over time, however, through dialogic engagement taking place over and through unfolding political events, the movement's diverse intellectual strands reframed and reinforced their relationship by focusing less on their differences and more on an ecumenically shared populist critique of judicial power emphasizing a virtuousdemosarrayed against an ideologically driven, antidemocratic, law-wielding elite. During this formative period, besides advocating a particular approach to textual interpretation, constitutional discourse played a critical role in fashioning movement symbols and signifiers, forming hopes and apprehensions, defining threats and reassurances, marking friends and enemies, stimulating feelings of belonging and alienation, fidelity and betrayal, and evoking both rational logics and intense emotions—all of which motivate and inform the heavily constitutionalized politics of American conservatism today.
TRAVELLING WAVE SOLUTIONS FOR DOUBLY DEGENERATE REACTION–DIFFUSION EQUATIONS
Authors: MANSOUR M. B. A.
Published: March 2011

This paper concerns a nonlinear doubly degenerate reaction–diffusion equation which appears in a bacterial growth model and is also of considerable mathematical interest. A travelling wave analysis for the equation is carried out. In particular, the qualitative behaviour of both sharp and smooth travelling wave solutions is analysed. This travelling wave behaviour is also verified by some numerical computations for a special case.
The First BIALL Supplier of the Year Award: a Look Behind the Scenes at the Development Process
Authors: Percik David
Published: March 2011

David Percik, Chair of the BIALL Legal Information Group traces the history of this award, which was presented for the first time to Wildy's at the BIALL Conference in June 2010.
The First BIALL Supplier of the Year Award: a Conversation with John Sinkins of Wildy's
Authors: Scorey Sue
Published: March 2011

In June 2010 the first BIALL Supplier of the Year award was made to Wildy & Sons Ltd, following a survey of BIALL members. The chair of the Awards and Bursaries Committee at the time of the award was Susan Scorey. Some time after the event she talked to John Sinkins, Managing Director of Wildy's, about the award and customer relations more generally.
Vendor Liaison: the Canadian Perspective
Authors: Mireau Shaunna
Published: March 2011

This article by Shaunna Mireau contains a brief update on the activities of the Canadian Association of Law Libraries Vendor Liaison Committee and shares the unique features of the relationships between Canadian law librarians and the vendor community.
Negotiation of Contracts. Planning for the Unknown with Boilerplate Clauses
Authors: Fogden Fiona
Published: March 2011

Fiona Fogden gave a very practical talk at the BIALL Conference 2010 in Brighton on contract negotiation with online vendors and it has been held over to this issue of LIM as it fits so well with our vendor relations theme.
Judge Stephen Schwebel: International Jurist Extraordinaire
Authors: Dingle Lesley
Published: March 2011

This is a further contribution to the Squire Law Library Eminent Scholars Archive by Lesley Dingle. It is based on interviews with Stephen Schwebel about his distinguished career as an international jurist in the United States and at the International Court of Justice.
The future of Afghanistan: an Afghan responsibility
Authors: Rahim Taiba
Published: March 2011

Bad news about Afghanistan is a daily reality. War has plagued the country for three uninterrupted decades. Afghan women and men face daunting survival struggles. The majority of them have known nothing else but war. Considerable responsibility lies on the shoulders of Afghans themselves, who have caused extensive suffering for their fellow countrywomen and men. This article, however, argues that the future of Afghanistan lies in Afghan hands. The solution to its current problems cannot and will not come from outside. It is time for Afghan men and women to confront their problems, to address their divisions, and to envisage home-grown solutions.
The mid‐Pleistocene transition in the subtropical southwest Pacific
Authors: Russon T. , Elliot M. , Sadekov A. , Cabioch G. , Corrège T. , De Deckker P.
Published: March 2011

Reconstructions of subtropical southwest Pacific climate variability over the Pleistocene were derived from coupled planktic foraminiferal δ18O‐Mg/Ca measurements taken from a southern Coral Sea sediment core. A clear shift from ∼40 kyr to ∼100 kyr modes of reconstructed glacial‐interglacial sea surface temperature (SST) variability is seen over the mid‐Pleistocene transition, and these fluctuations are shown to have remained coherent with the orbital obliquity cycle across the transition. The likely origin of this strong obliquity signal in subtropical southwest Pacific SST is shown to be the southern high latitudes, and comparison with existing SST reconstructions from the equatorial Pacific is consistent with the communication of the signal occurring principally by greenhouse gas forcing. In contrast to the SST reconstruction, regional hydrological cycle variability (based on the calculated local component of δ18Osw change) does not show significant coherence with obliquity after ∼1000 ka. The decoupling of the SST and hydrological cycle responses over the mid‐Pleistocene transition allows constraints to be placed on the evolution and extent of orbitally paced fluctuations within the coupled low‐latitude ocean‐atmosphere system.
Attenuation of radio signals by the ionosphere of Mars: Theoretical development and application to MARSIS observations
Authors: Withers Paul
Published: March 2011

We investigate the ionospheric conditions required to explain Mars Express Mars Advanced Radar for Subsurface and Ionosphere Sounding topside radar sounder observations of ionospheric attenuation in excess of 13 dB at 5 MHz during solar energetic particle events. We develop theoretical expressions for the attenuation caused by a layer of ionospheric plasma in cases of high, intermediate, and low radio frequency relative to the electron‐neutral collision frequency at the ionospheric layer. We apply these relationships to four layers: the M2 layer produced at 120 km by solar extreme ultraviolet photons, the M1 layer produced at 100 km by solar X‐ray photons and associated electron impact ionization, the meteoric layer produced at 85 km by meteoroid ablation, and a putative plasma layer produced at 35 km by cosmic rays. Attenuation is weaker in the M2 layer than in the M1 layer. Attenuation in the M1 and meteoric layers are comparable, although their properties are quite variable. The greatest attenuation for radio frequencies above 50 MHz occurs in the predicted plasma layer at 35 km, but its effects are relatively small at lower frequencies. If optimally located with a peak altitude of 50 km, a layer with a peak plasma density of 109 m−3 is sufficient to explain the observed 13 dB attenuation. Although the electron densities produced by solar energetic particle events at Mars have not been directly simulated, the required electron densities are plausible. However, the altitude at which solar energetic particles produce plasma is uncertain.
Depleted dissolved organic carbon and distinct bacterial communities in the water column of a rapid-flushing coral reef ecosystem
Authors: Nelson Craig E , Alldredge Alice L , McCliment Elizabeth A , Amaral-Zettler Linda A , Carlson Craig A
Published: March 2011

Coral reefs are highly productive ecosystems bathed in unproductive, low-nutrient oceanic waters, where microbially dominated food webs are supported largely by bacterioplankton recycling of dissolved compounds. Despite evidence that benthic reef organisms efficiently scavenge particulate organic matter and inorganic nutrients from advected oceanic waters, our understanding of the role of bacterioplankton and dissolved organic matter (DOM) in the interaction between reefs and the surrounding ocean remains limited. In this study, we present the results of a 4-year study conducted in a well-characterized coral reef ecosystem (Paopao Bay, Moorea, French Polynesia) where changes in bacterioplankton abundance and dissolved organic carbon (DOC) concentrations were quantified and bacterial community structure variation was examined along spatial gradients of the reef:ocean interface. Our results illustrate that the reef is consistently depleted in concentrations of both DOC and bacterioplankton relative to offshore waters (averaging 79 μmol l−1 DOC and 5.5 × 108 cells l−1 offshore and 68 μmol l−1 DOC and 3.1 × 108 cells l−1 over the reef, respectively) across a 4-year time period. In addition, using a suite of culture-independent measures of bacterial community structure, we found consistent differentiation of reef bacterioplankton communities from those offshore or in a nearby embayment across all taxonomic levels. Reef habitats were enriched in Gamma-, Delta-, and Betaproteobacteria, Bacteriodetes, Actinobacteria and Firmicutes. Specific bacterial phylotypes, including members of the SAR11, SAR116, Flavobacteria, and Synechococcus clades, exhibited clear gradients in relative abundance among nearshore habitats. Our observations indicate that this reef system removes oceanic DOC and exerts selective pressures on bacterioplankton community structure on timescales approximating reef water residence times, observations which are notable both because fringing reefs do not exhibit long residence times (unlike those characteristic of atoll lagoons) and because oceanic DOC is generally recalcitrant to degradation by ambient microbial assemblages. Our findings thus have interesting implications for the role of oceanic DOM and bacterioplankton in the ecology and metabolism of reef ecosystems.
Carbon, nitrogen and O2 fluxes associated with the cyanobacterium Nodularia spumigena in the Baltic Sea
Authors: Ploug Helle , Adam Birgit , Musat Niculina , Kalvelage Tim , Lavik Gaute , Wolf-Gladrow Dieter , Kuypers Marcel M M
Published: March 2011

Photosynthesis, respiration, N2 fixation and ammonium release were studied directly in Nodularia spumigena during a bloom in the Baltic Sea using a combination of microsensors, stable isotope tracer experiments combined with nanoscale secondary ion mass spectrometry (nanoSIMS) and fluorometry. Cell-specific net C- and N2-fixation rates by N. spumigena were 81.6±6.7 and 11.4±0.9 fmol N per cell per h, respectively. During light, the net C:N fixation ratio was 8.0±0.8. During darkness, carbon fixation was not detectable, but N2 fixation was 5.4±0.4 fmol N per cell per h. Net photosynthesis varied between 0.34 and 250 nmol O2 h−1 in colonies with diameters ranging between 0.13 and 5.0 mm, and it reached the theoretical upper limit set by diffusion of dissolved inorganic carbon to colonies (>1 mm). Dark respiration of the same colonies varied between 0.038 and 87 nmol O2 h−1, and it reached the limit set by O2 diffusion from the surrounding water to colonies (>1 mm). N2 fixation associated with N. spumigena colonies (>1 mm) comprised on average 18% of the total N2 fixation in the bulk water. Net NH4+ release in colonies equaled 8–33% of the estimated gross N2 fixation during photosynthesis. NH4+ concentrations within light-exposed colonies, modeled from measured net NH4+ release rates, were 60-fold higher than that of the bulk. Hence, N. spumigena colonies comprise highly productive microenvironments and an attractive NH4+ microenvironment to be utilized by other (micro)organisms in the Baltic Sea where dissolved inorganic nitrogen is limiting growth.
Protist diversity in a permanently ice-covered Antarctic Lake during the polar night transition
Authors: Bielewicz Scott , Bell Elanor , Kong Weidong , Friedberg Iddo , Priscu John C , Morgan-Kiss Rachael M
Published: March 2011

The McMurdo Dry Valleys of Antarctica harbor numerous permanently ice-covered lakes, which provide a year-round oasis for microbial life. Microbial eukaryotes in these lakes occupy a variety of trophic levels within the simple aquatic food web ranging from primary producers to tertiary predators. Here, we report the first molecular study to describe the vertical distribution of the eukaryotic community residing in the photic zone of the east lobe (ELB) and west lobe (WLB) of the chemically stratified Lake Bonney. The 18S ribosomal RNA (rRNA) libraries revealed vertically stratified populations dominated by photosynthetic protists, with a cryptophyte dominating shallow populations (ELB–6 m; WLB–10 m), a haptophyte occupying mid-depths (both lobes 13 m) and chlorophytes residing in the deepest layers (ELB–18 and 20 m; WLB–15 and 20 m) of the photic zone. A previously undetected stramenopile occurred throughout the water column of both lobes. Temporal variation in the eukaryotic populations was examined during the transition from Antarctic summer (24-h sunlight) to polar night (complete dark). Protist diversity was similar between the two lobes of Lake Bonney due to exchange between the photic zones of the two basins via a narrow bedrock sill. However, vertical and temporal variation in protist distribution occurred, indicating the influence of the unique water chemistry on the biology of the two dry valley watersheds.
IS5 inserts upstream of the master motility operon flhDC in a quasi-Lamarckian way
Authors: Wang Xiaoxue , Wood Thomas K
Published: March 2011

Mutation rates may be influenced by the environment. Here, we demonstrate that insertion sequence IS5 in Escherichia coli inserts into the upstream region of the flhDC operon in a manner that depends on whether the environment permits motility; this operon encodes the master regulator of cell motility, FlhDC, and the IS5 insertion increases motility. IS5 inserts upstream of flhD+ when cells are grown on soft-agar plates that permit swimming motility, but does not insert upstream of this locus on hard-agar plates that do not permit swimming motility or in planktonic cultures. Furthermore, there was only one IS5 insertion event on soft-agar plates, indicating insertion of IS5 into flhDC is not due to general elevated IS5 transposition throughout the whole genome. We also show that the highly motile cells with IS5 upstream of flhD+ have greater biofilm formation, although there is a growth cost due to the energetic burden of the enhanced motility as these highly motile cells have a lower yield in rich medium and reduced growth rate. Functional flagella are required for IS5 insertion upstream of flhD+ as there was no IS5 insertion upstream of flhD+ for flhD, flgK and motA mutants, and the mutation is stable. Additionally, the IS5 mutation occurs during biofilm formation, which creates genetic and phenotypic diversity. Hence, the cells appear to ‘sense’ whether motility is feasible before a sub-population undergoes a mutation to become hypermotile; this sensing appears related to the master transcription regulator, FlhDC.
Reversal in competitive dominance of a toxic versus non-toxic cyanobacterium in response to rising CO2
Authors: Van de Waal Dedmer B , Verspagen Jolanda M H , Finke Jan F , Vournazou Vasiliki , Immers Anne K , Kardinaal W Edwin A , Tonk Linda , Becker Sven , Van Donk Ellen , Visser Petra M , Huisman Jef
Published: March 2011

Climate change scenarios predict a doubling of the atmospheric CO2 concentration by the end of this century. Yet, how rising CO2 will affect the species composition of aquatic microbial communities is still largely an open question. In this study, we develop a resource competition model to investigate competition for dissolved inorganic carbon in dense algal blooms. The model predicts how dynamic changes in carbon chemistry, pH and light conditions during bloom development feed back on competing phytoplankton species. We test the model predictions in chemostat experiments with monocultures and mixtures of a toxic and non-toxic strain of the freshwater cyanobacterium Microcystis aeruginosa. The toxic strain was able to reduce dissolved CO2 to lower concentrations than the non-toxic strain, and became dominant in competition at low CO2 levels. Conversely, the non-toxic strain could grow at lower light levels, and became dominant in competition at high CO2 levels but low light availability. The model captured the observed reversal in competitive dominance, and was quantitatively in good agreement with the results of the competition experiments. To assess whether microcystins might have a role in this reversal of competitive dominance, we performed further competition experiments with the wild-type strain M. aeruginosa PCC 7806 and its mcyB mutant impaired in microcystin production. The microcystin-producing wild type had a strong selective advantage at low CO2 levels but not at high CO2 levels. Our results thus demonstrate both in theory and experiment that rising CO2 levels can alter the community composition and toxicity of harmful algal blooms.
Weight Change and Cognitive Function: Findings From the Women's Health Initiative Study of Cognitive Aging
Authors: Driscoll Ira , Espeland Mark A. , Wassertheil‐Smoller Sylvia , Gaussoin Sarah A. , Ding Jingzhong , Granek Iris A. , Ockene Judith K. , Phillips Lawrence S. , Yaffe Kristine , Resnick Susan M. ,   For the Women's Health Initiative Study of Cognitive Aging
Published: March 2011

Although studies exploring relationships between obesity and cognitive impairment in the elderly are conflicting, literature suggests that overweight and obesity may be protective against cognitive impairment and dementia in older women. We examine the associations between changes in weight and waist circumference (WC) with global and domain‐specific cognitive function in a large, well‐defined cohort of 2,283 older, postmenopausal women (aged 65–79) prospectively followed through the Women's Health Initiative (WHI) Study of Cognitive Aging (WHISCA). We assessed the associations between changes in weight and WC collected up to 5 years before WHISCA enrollment and mean levels of global and domain‐specific cognitive performance across an average of 5.4 years of subsequent follow‐up. There was a lack of associations between weight and cognition in women who remained stable or gained weight. The only significant relationships observed were in association with weight loss (P ≤ 0.05), most likely signaling incipient disease. Moreover, cognition was not related to changes in WC. Relationships were largely independent of initial BMI, self‐reported caloric intake or dieting. The lack of associations between weight gain and cognition in women is consistent with the existing literature.
The Relationship Among Central Obesity, Systemic Inflammation, and Left Ventricular Diastolic Dysfunction as Determined by Structural Equation Modeling
Authors: Wu Cho‐Kai , Yang Chung‐Yi , Lin Jou‐Wei , Hsieh Hung‐Jen , Chiu Fu‐Chun , Chen Jen‐Junn , Lee Jen‐Kuang , Huang Shu‐Wei , Li Hung‐Yuan , Chiang Fu‐Tien , Chen Jin‐Jer , Tsai Chia‐Ti
Published: March 2011

The purpose of this study was to investigate the associations among central obesity, inflammation, and left ventricular (LV) diastolic dysfunction by structural equation modeling. Echocardiographic parameters were assessed in 102 otherwise‐healthy adults over age 30. The participants were classified as having LV diastolic dysfunction by echocardiographic findings including mitral inflow E/A ratio <1, deceleration time >220 cm/s, or decreased peak annular early diastolic velocity in tissue Doppler imaging or otherwise the control group. Serum C‐reactive protein (CRP) and lipid profile were also measured. The homeostasis model of insulin resistance (HOMA) was calculated. Central obesity was assessed by computerized tomography (CT) at the L4 level. In a multivariate regression analysis, the relationship between visceral adipose tissue (VAT) and LV diastolic dysfunction became insignificant when CRP was introduced into the model, although CRP itself was significantly associated with LV diastolic dysfunction (odds ratio (OR): 1.32, 95% confidence interval (CI): 1.01–1.72, P = 0.04). A significant correlation was also found between VAT and CRP (r = 0.70; P < 0.001). We then performed path analysis as illustrated by the structural equation model. This proved our hypotheses that VAT might affect LV diastolic dysfunction through the effect of CRP (total fat load with inflammation (B = 1.133, P < 0.001) and that inflammation might affect LV diastolic dysfunction (B = 0.373. P < 0.001)). Using structural equation modeling, we concluded that higher amounts of VAT were associated with low‐grade inflammation and this may lead to subclinical LV diastolic dysfunction in otherwise‐healthy subjects.
Body Adiposity and Type 2 Diabetes: Increased Risk With a High Body Fat Percentage Even Having a Normal BMI
Authors: Gómez‐Ambrosi Javier , Silva Camilo , Galofré Juan C. , Escalada Javier , Santos Silvia , Gil María J. , Valentí Victor , Rotellar Fernando , Ramírez Beatriz , Salvador Javier , Frühbeck Gema
Published: March 2011

Obesity is the major risk factor for the development of prediabetes and type 2 diabetes. BMI is widely used as a surrogate measure of obesity, but underestimates the prevalence of obesity, defined as an excess of body fat. We assessed the presence of impaired glucose tolerance or impaired fasting glucose (both considered together as prediabetes) or type 2 diabetes in relation to the criteria used for the diagnosis of obesity using BMI as compared to body fat percentage (BF%). We performed a cross‐sectional study including 4,828 (587 lean, 1,320 overweight, and 2,921 obese classified according to BMI) white subjects (66% females), aged 18–80 years. BMI, BF% determined by air‐displacement plethysmography (ADP) and conventional blood markers of glucose metabolism and lipid profile were measured. We found a higher than expected number of subjects with prediabetes or type 2 diabetes in the obese category according to BF% when the sample was globally analyzed (P < 0.0001) and in the lean BMI‐classified subjects (P < 0.0001), but not in the overweight or obese‐classified individuals. Importantly, BF% was significantly higher in lean (by BMI) women with prediabetes or type 2 diabetes as compared to those with normoglycemia (NG) (35.5 ± 7.0 vs. 30.3 ± 7.7%, P < 0.0001), whereas no differences were observed for BMI. Similarly, increased BF% was found in lean BMI‐classified men with prediabetes or type 2 diabetes (25.2 ± 9.0 vs. 19.9 ± 8.0%, P = 0.008), exhibiting no differences in BMI or waist circumference. In conclusion, assessing BF% may help to diagnose disturbed glucose tolerance beyond information provided by BMI and waist circumference in particular in male subjects with BMI <25 kg/m2 and over the age of 40.
Body Fat Content Determination in Premenopausal, Overweight, and Obese Young Women Using DXA and FT‐NIR
Authors: Josse Andrea R. , Azizian Hormoz , French Shannon B. , Kramer John K.G. , Phillips Stuart M.
Published: March 2011

Even though BMI is the most commonly used method for assessing and monitoring obesity, it does not take into account the individual's body fat content assuming instead that body mass is closely associated with body fat, which is a tenuous assumption. The aim of this study was to make a direct comparison between measurements of body fat content using a convenient and rapid Fourier transform near‐infrared (FT‐NIR) spectroscopy and dual‐energy X‐ray absorptiometry (DXA). We recruited 52, premenopausal women (age range 19–45), all of whom had a BMI that classified them as either overweight or obese (range: 27–40 kg/m2, mean: 31.1 ± 3.7 kg/m2) and indicated a statistically significant linear relationship between the fat content in kilograms measured by FT‐NIR and DXA (r = 0.95, P < 0.001). Bland–Altman analysis showed that almost all the differences between two measurements fell within 2 s.d. We report here that the FT‐NIR method provided comparable measurements of subcutaneous body fat content similar to those of total fat obtained using DXA. The FT‐NIR method is a lower cost, easy to use and transport, and, based on comparison with DXA, an accurate method to measure body fat content. We propose that FT‐NIR is an ideal method for safe repeat measurements in large trials or in screening and monitoring individuals during interventions in which changes in body fat will occur.
The Lipid Accumulation Product Is Associated With Increased Mortality in Normal Weight Postmenopausal Women
Authors: Wehr Elisabeth , Pilz Stefan , Boehm Bernhard O. , März Winfried , Obermayer‐Pietsch Barbara
Published: March 2011

Lipid accumulation product (LAP) is an emerging cardiovascular risk factor, which is calculated from waist circumference (WC) and triglyceride (TG) levels. The aim of this study was to elucidate the relationship between LAP and cardiovascular mortality as well as the presence of type 2 diabetes with respect to gender‐specific differences. We determined WC and fasting TG levels and the cardiovascular and metabolic phenotypes coronary artery disease (CAD), hypertension, metabolic syndrome, and diabetes mellitus in 2,279 men and 875 postmenopausal women who were routinely referred to coronary angiography. The LAP was calculated as (WC (cm) — 65) × (TG (mmol/l)) for men and as (WC (cm) — 58) × (TG (mmol/l)) for women. LAP levels were independently associated with congestive heart failure mortality in all postmenopausal women and with all‐cause mortality in diabetic postmenopausal women but not in men. Multivariable‐adjusted hazard ratios (with 95% confidence intervals) for all‐cause, cardiovascular, and congestive heart failure mortality in the third compared to the first LAP tertile were 4.28 (1.94–9.44; P < 0.001), 3.47 (1.28–9.40; P = 0.015), and 10.77 (1.21–95.88; P = 0.033), respectively, in normal weight postmenopausal women, whereas no significant associations were found in men. LAP levels were highly associated with type 2 diabetes in all subjects, postmenopausal women, and men. High LAP values are predictive of mortality independently of other cardiovascular risk factors in normal weight and diabetic postmenopausal women but not in men. Type 2 diabetes (T2DM) was highly associated with LAP in women and men. Our study validates an inexpensive and simple risk profiling that may allow identifying postmenopausal women at high cardiovascular risk.
Maternal Serum Lipids During Pregnancy and Infant Birth Weight: The Influence of Prepregnancy BMI
Authors: Misra Vinod K. , Trudeau Sheri , Perni Uma
Published: March 2011

Maternal obesity may be associated with metabolic factors that affect the intrauterine environment, fetal growth, and the offspring's long‐term risk for chronic disease. Among these factors, maternal serum lipids play a particularly important role. Our objective was to estimate the influence of variation in maternal serum lipid levels on variation in infant birth weight (BW) in overweight/obese and normal weight women. In a prospective cohort of 143 gravidas, we measured maternal serum levels of total cholesterol (TC), low‐density lipoprotein cholesterol (LDL‐C), high‐density lipoprotein cholesterol (HDL‐C), and triglycerides (TG) at 6–10, 10–14, 16–20, 22–26, and 32–36 weeks gestation. Effects of maternal serum lipid levels on infant BW adjusted for gestational age at delivery (aBW) were analyzed using linear regression models. In analyses stratified by maternal prepregnancy BMI categorized as normal (≤25.0 kg/m2) and overweight/obese (>25.0 kg/m2), we found a significant (P < 0.05) inverse association between aBW and HDL‐C at all time points starting at 10 weeks gestation in overweight/obese women. No significant effect was found in normal weight women. In contrast, increased maternal serum TG was significantly associated with increased aBW only for normal weight women at 10–14 and 22–26 weeks gestation. Variation in aBW is not associated with variation in maternal serum TC or LDL‐C for either stratum at any time point. We postulate that such differences may be involved in the “physiological programming” that influences later risk of chronic disease in the infants of overweight/obese mothers.
Endosonografisch gestützte Dränagen - Indikationen und Technik
Authors: Will U. , Müller A. , Wanzar I. , Füldner F. , Meyer F.
Published: March 2011

Die unmittelbare Nähe des Pankreas und der Gallenwege zum Intestinum eröffnet für die therapeutische EUS völlig neue Indikationsgebiete. Eine transmurale Dränage von Pseudozysten oder Abszessen des Pankreas mit der Endosonografie ist ein sicheres und komplikationsarmes Verfahren mit einer im Vergleich zur endoskopischen Dränage höheren technischen Erfolgsrate. Ein kombiniertes Vorgehen der internen EUS-Dränage mit einer perkutanen Dränage kann die Anzahl der endoskopischen Interventionen zur Sanierung von infizierten Nekrosehöhlen minimieren und den Langzeiterfolg verbessern. Die interne EUS-geführte Dränage (EUCD) von gestauten Gallenwegen bei nicht sondierbaren oder nicht erreichbaren Papillen nach Operation oder aufgrund maligner Obturation ist ein interessanter therapeutischer Ansatz zur Vermeidung einer temporären oder dauerhaften PTCD. Für symptomatische Patienten mit erweitertem Pankreasgang nach Operation oder nach Nekrosektomie (abgehängter Pankreasgang, DPTS) bzw. mit persistierenden Pankreasfisteln gibt es bisher keine endoskopische Möglichkeit der Gangentlastung. Mithilfe der EUS gelingt es den gestauten Pan­kreasgang in den Magen oder das Duodenum ­abzuleiten (EUPD) und dem Patienten damit eine erneute Operation zu ersparen. Im Beitrag werden Therapiestandards von pankreatischen Pseudozysten, Abszessen und Nekrosen sowie neue Techniken in der EUS-geführten internen Gallengangsdränage und Pankreasgangdränage besprochen und ihre Relevanz im klinischen Alltag unter Einbeziehung aktueller Literaturdaten gewürdigt.
Chirality dependence of nanoscale ferromagnetic NOT gates
Authors: Lewis E. R. , Petit D. , O’Brien L. , Zeng H. T. , Read D. E. , Cowburn R. P.
Published: March 2011

The behavior of a transverse domain wall (DW) interacting with a ferromagnetic NOT gate is studied with specific emphasis on the role of the DW chirality (sense of rotation of magnetization crossing the DW). We examine both the effect of the incoming DW chirality on the operation of the NOT gate and the effect of the gate on the DW chirality. We find that the chirality of the incoming DW does not affect the range of fields over which the NOT gate operates correctly. The effect of the NOT gate on the DW chirality depends on the chirality of the incoming DW: when the DW is incident on the NOT gate with the wide side of the DW on the inside of the V-shape formed by the gate, the chirality is conserved, but when the DW is incident on the gate with its wide side on the outside of the V-shape, the chirality may reverse.
Determination of effective mass of heavy hole from phonon-assisted excitonic luminescence spectra in ZnO
Authors: Shi S. L. , Xu S. J.
Published: March 2011

Longitudinal optical (LO) phonon-assisted luminescence spectra of free excitons in high-quality ZnO crystal were investigated both experimentally and theoretically. By using the rigorous Segall–Mahan model based on the Green’s function, good agreement between the experimental emission spectra involving one or two LO phonons and theoretical spectra can be achieved when only one adjustable parameter (effective mass of heavy hole) was adopted. This leads to determination of the heavy-hole effective mass mh⊥ = (0.8 m0 and mh∥ = 5.0 m0) in ZnO. Influence of anisotropic effective masses of heavy holes on the phonon sidebands is also discussed.
Local compositional environment of Er in ZnS:ErF3 thin film electroluminescent phosphors
Authors: Davidson Mark R. , Stoupin Stanislav , DeVito David , Collingwood Joanna F. , Segre Carlo , Holloway Paul H.
Published: March 2011

ZnS:Er thin film electroluminescent phosphors have been shown to exhibit a marked maximum in the near infrared emission (NIR) after a 425 °C post-deposition anneal with a very narrow temperature window of ±25 °C for optimal NIR emission. Extended X-ray absorption fine structure (EXAFS) spectroscopy has been obtained from both the Zn and Er edges in order to examine the local structure of the host and dopant in this NIR phosphor material. Interestingly, the addition of only ∼0.5 mol. % of Er as ErF3 into the host is found to reduce the Zn–S bond length of one of the two nearest Zn–S shells by 0.6 Å relative to high-quality, atomic layer epitaxy (ALE) grown, pure ZnS. The coordination number of this shorter Zn–S bond increases after the optimal 425 °C anneal. Longer range fits indicate a highly disordered structure, overall, consistent with earlier TEM results. Erbium-L3 EXAFS data from the second and third shells show increasing crystallinity with increasing annealing temperature in the vicinity of the Er dopant. Data from the first shell cannot be fit with S atoms, but are fit equally well with either O or F. Comparison with earlier analyses indicates that the Er is most likely surrounded by F in the first shell. Based on these data and previous studies, we develop a model in which the Er dopant is present as an Er:Fx complex with associated S vacancies, which may include one sulfur atom remaining in the Er nearest shell. Upon annealing, there is a reduction in the F present and a rearrangement of the crystal structure in the vicinity of the Er atom. Optimum annealing conditions occur when optimal crystalline environment is achieved prior to the loss of too much F from the Er:Fx complex.