bluuebunny/crossref_metadata_2025 huggingface dataset:
Degenerate real hypersurfaces in ℂ² with few automorphisms
Authors: Ebenfelt Peter , Lamel Bernhard , Zaitsev Dmitri
Published: February 2009

We introduce new biholomorphic invariants for real-analytic hypersurfaces in

C

2

\mathbb {C}^2

and show how they can be used to show that a hypersurface possesses few automorphisms. We give conditions, in terms of the new invariants, guaranteeing that the stability group is finite, and give (sharp) bounds on the cardinality of the stability group in this case. We also give a sufficient condition for the stability group to be trivial. The main technical tool developed in this paper is a complete (formal) normal form for a certain class of hypersurfaces. As a byproduct, a complete classification, up to biholomorphic equivalence, of the finite type hypersurfaces in this class is obtained.
Non-degeneracy of Wiener functionals arising from rough differential equations
Authors: Cass Thomas , Friz Peter , Victoir Nicolas
Published: February 2009

Malliavin Calculus is about Sobolev-type regularity of functionals on Wiener space, the main example being the Itô map obtained by solving stochastic differential equations. Rough path analysis is about strong regularity of the solution to (possibly stochastic) differential equations. We combine arguments of both theories and discuss the existence of a density for solutions to stochastic differential equations driven by a general class of non-degenerate Gaussian processes, including processes with sample path regularity worse than Brownian motion.
Blow-up of solutions of nonlinear parabolic inequalities
Authors: Taliaferro Steven
Published: February 2009

We study nonnegative solutions

u
(
x
,
t
)

u(x,t)

of the nonlinear parabolic inequalities
\[

a

u
λ

≤

u
t

−
Δ
u
≤

u
λ

au^\lambda \le u_t - \Delta u \le u^\lambda

\]
in various subsets of

R

n

×

R

\textbf {R}^n\times \textbf {R}

, where

λ
>

n
+
2

n

\lambda >\frac {n+2}{n}

and

a
∈
(
0
,
1
)

a\in (0,1)

are constants. We show that changing the value of

a
a

in the open interval

(
0
,
1
)

(0,1)

can dramatically affect the blow-up of these solutions.
Green’s matrices of second order elliptic systems with measurable coefficients in two dimensional domains
Authors: Dong Hongjie , Kim Seick
Published: February 2009

We study Green’s matrices for divergence form, second order strongly elliptic systems with bounded measurable coefficients in two dimensional domains. We establish existence, uniqueness, and pointwise estimates of Green’s matrices.
Asymptotic estimates for rational linear spaces on hypersurfaces
Authors: Parsell Scott
Published: February 2009

We develop a repeated efficient differencing procedure for estimating mean values of certain multidimensional exponential sums over smooth numbers. As a consequence, we obtain asymptotic lower bounds for the number of linear spaces of fixed dimension up to a given height lying on the hypersurface defined by an additive equation.
Semiprojectivity for certain purely infinite 𝐶*-algebras
Authors: Spielberg Jack
Published: February 2009

It is proved that classifiable simple separable nuclear purely infinite

C
∗

C^*

-algebras having finitely generated

K
K

-theory and torsion-free

K

1

K_{1}

are semiprojective. This is accomplished by exhibiting these algebras as

C
∗

C^*

-algebras of infinite directed graphs.
Computability, noncomputability and undecidability of maximal intervals of IVPs
Authors: Graça D.S. , Zhong N. , Buescu J.
Published: February 2009

Let

(
α
,
β
)
⊆

R

(\alpha ,\beta )\subseteq \mathbb {R}

denote the maximal interval of existence of solutions for the initial-value problem
\[

{

d
x

d
t

=
f
(
t
,
x
)
,
x
(

t

0

)
=

x

0

,

\left \{ \begin {array} [c]{l}\frac {dx}{dt}=f(t,x), x(t_{0})=x_{0}, \end {array} \right .

\]
where

E
E

is an open subset of

R

m
+
1

\mathbb {R}^{m+1}

,

f
f

is continuous in

E
E

and

(

t

0

,

x

0

)
∈
E

(t_{0},x_{0})\in E

. We show that, under the natural definition of computability from the point of view of applications, there exist initial-value problems with computable

f
f

and

(

t

0

,

x

0

)

(t_{0},x_{0})

whose maximal interval of existence

(
α
,
β
)

(\alpha ,\beta )

is noncomputable. The fact that

f
f

may be taken to be analytic shows that this is not a lack of the regularity phenomenon. Moreover, we get upper bounds for the “degree of noncomputability” by showing that

(
α
,
β
)

(\alpha ,\beta )

is r.e. (recursively enumerable) open under very mild hypotheses. We also show that the problem of determining whether the maximal interval is bounded or unbounded is in general undecidable.
Effective refining of Borel coverings
Authors: Debs Gabriel , Saint Raymond Jean
Published: February 2009

Given a countable family

(

Γ

i

)

i
∈
I

(\mathbf {\Gamma }_i)_{i\in I}

of additive or multiplicative Baire classes (

Γ

i

=

Σ

ξ
i

0

\mathbf {\Gamma }_i=\mathbf {\Sigma }^0_{\xi _i}

or

Π

ξ
i

0

\mathbf {\Pi }^0_{\xi _i}

) we investigate the following complexity problem: Let

(

A
i

)

i
∈
I

(A_i)_{i\in I}

be a Borel covering of

ω
ω

\omega ^\omega

and assume that there exists some covering

(

B
i

)

i
∈
I

(B_i)_{i\in I}

with

B
i

⊂

A
i

B_i\subset A_i

and

B
i

∈

Γ

i

B_i\in \mathbf {\Gamma }_i

for all

i
i

; can one find such a family

(

B
i

)

i
∈
I

(B_i)_{i\in I}

in

Δ
1
1

(
α
)

\varDelta ^1_1(\alpha )

where

α
∈

ω
ω

\alpha \in \omega ^\omega

is any reasonable code for the families

(

A
i

)

i
∈
I

(A_i)_{i\in I}

and

(

Γ

i

)

i
∈
I

(\mathbf {\Gamma }_i)_{i\in I}

? The main result of the paper will give a full characterization of those families

(

Γ

i

)

i
∈
I

(\mathbf {\Gamma }_i)_{i\in I}

for which the answer is positive. For example we will show that this is the case if

I
I

is finite or if all the Baire classes

Γ

i

\mathbf {\Gamma }_i

are additive, but in the general case the answer depends on the distribution of the multiplicative Baire classes inside the family

(

Γ

i

)

i
∈
I

(\mathbf {\Gamma }_i)_{i\in I}

.
Comparative analysis of H2A.Z nucleosome organization in the human and yeast genomes
Authors: Tolstorukov Michael Y. , Kharchenko Peter V. , Goldman Joseph A. , Kingston Robert E. , Park Peter J.
Published: February 2009

Eukaryotic DNA is wrapped around a histone protein core to constitute the fundamental repeating units of chromatin, the nucleosomes. The affinity of the histone core for DNA depends on the nucleotide sequence; however, it is unclear to what extent DNA sequence determines nucleosome positioning in vivo, and if the same rules of sequence-directed positioning apply to genomes of varying complexity. Using the data generated by high-throughput DNA sequencing combined with chromatin immunoprecipitation, we have identified positions of nucleosomes containing the H2A.Z histone variant and histone H3 trimethylated at lysine 4 in human CD4+ T-cells. We find that the 10-bp periodicity observed in nucleosomal sequences in yeast and other organisms is not pronounced in human nucleosomal sequences. This result was confirmed for a broader set of mononucleosomal fragments that were not selected for any specific histone variant or modification. We also find that human H2A.Z nucleosomes protect only ∼120 bp of DNA from MNase digestion and exhibit specific sequence preferences, suggesting a novel mechanism of nucleosome organization for the H2A.Z variant.
Ghrelin receptor agonist (TZP‐101) accelerates gastric emptying in adults with diabetes and symptomatic gastroparesis
Authors: EJSKJAER N. , VESTERGAARD E. T. , HELLSTRÖM P. M. , GORMSEN L. C. , MADSBAD S. , MADSEN J. L. , JENSEN T. A. , PEZZULLO J. C. , CHRISTIANSEN J. S. , SHAUGHNESSY L. , KOSUTIC G.
Published: February 2009

Background  TZP‐101 is a synthetic, selective ghrelin agonist in development for gastroparesis.

Aim  To assess safety and effects of TZP‐101 in diabetes patients with symptomatic gastroparesis.

Methods  Adults with type 1 or type 2 diabetes mellitus received placebo and TZP‐101 (80, 160, 320 or 600 μg/kg) infusions in a cross‐over manner following a radiolabelled meal. Blood glucose levels were stabilized using a hyperinsulinemic‐euglycemic clamp. Primary endpoints were gastric half emptying and latency times. Secondary measures included assessment of gastroparesis symptoms and endocrine responses.

Results  Ten patients with type 1 (n = 7) or 2 (n = 3) diabetes, moderate‐to‐severe gastroparesis symptoms and ≥29% retention 4 h after a radiolabelled solid meal were enrolled. TZP‐101 produced significant reductions in solid meal half‐emptying (20%, P = 0.043) and latency (34%, P = 0.037) times vs. placebo. Reductions in overall postmeal symptom intensity (24%) and postprandial fullness (37%) following TZP‐101 infusion were not statistically significant. Most adverse events were mild and self‐limiting and there were no identifiable differences in numbers or types of adverse events between TZP‐101 and placebo.

Conclusions  This proof‐of‐concept study demonstrates that the ghrelin agonist TZP‐101 is well‐tolerated in diabetes patients with moderate‐to‐severe chronic gastroparesis and shows statistically significant improvements in gastric emptying.
Novel fungal disease in complex leaf‐cutting ant societies
Authors: HUGHES DAVID P. , EVANS HARRY C. , HYWEL‐JONES NIGEL , BOOMSMA JACOBUS J. , ARMITAGE SOPHIE A. O.
Published: February 2009

Abstract1. The leaf‐cutting ants practise an advanced system of mycophagy where they grow a fungus as a food source. As a consequence of parasite threats to their crops, they have evolved a system of morphological, behavioural, and chemical defences, particularly against fungal pathogens (mycopathogens).

2. Specific fungal diseases of the leaf‐cutting ants themselves have not been described, possibly because broad spectrum anti‐fungal defences against mycopathogens have reduced their susceptibility to entomopathogens.

3. Using morphological and molecular tools, the present study documents three rare infection events ofAcromyrmexandAttaleaf‐cutting ants byOphiocordycepsfungi, agenus of entomopathogens that is normally highly specific in its host choice.

4. As leaf‐cutting ants have been intensively studied, the absence of prior records ofOphiocordycepssuggests that these infections may be a novel event and that switching from one host to another is possible. To test the likelihood of this hypothesis, host switching was experimentally induced, and successfully achieved, among five distinct genera of ants, one of which was in a different sub‐family than the leaf‐cutter ants.

5. Given the substantial differences among the five host ants, the ability ofOphiocordycepsto shift between such distant hosts is remarkable; the results are discussed in the context of ant ecological immunology and fungal invasion strategies.
Four‐level interactions: herbivore use of ferns and subsequent parasitoid–hyperparasitoid performance
Authors: MORSE DOUGLASS H.
Published: February 2009

Abstract 1. Variables affecting species at the ends of trophic chains may modify the success of members with which they do not directly interact. The majority of such examples involve three trophic levels, but hyperparasitoids provide an excellent opportunity to examine four‐level relationships.

2. The gregarious hyperparasitoid Aprostocetus sp. (Hymenoptera: Eulophidae) commonly attacks the primary parasitoid Alabagrus texanus (Hymenoptera: Braconidae), by far the commonest parasitoid of the moth Herpetogramma theseusalis (Lepidoptera: Crambidae).

3. Larvae of this moth feed on ferns of two families, sensitive fern Onoclea sensibilis (Dryopteridaceae) and marsh fern Thelypteris palustris (Thelypteridaceae), in the study area, an old field in Maine, U.S.A.

4. I test the hypotheses that the ferns indirectly affect the reproductive success of the hyperparasitoids and that the ferns produce similar effects at intermediate links.

5. The moths experienced similar success on the two ferns, and the primary parasitoid performed similarly on moths reared from both ferns. The hyperparasitoid parasitized similar proportions of the primary parasitoid from moths that fed on sensitive fern and marsh fern.

6. However, hyperparasitoid broods on primary parasitoids from moths feeding on marsh fern contained approximately one‐third more offspring, whose individuals were significantly larger than those from sensitive fern, even though their hosts’ sizes did not differ significantly.

7. An indirect effect, related to the primary producers, thus strongly affected Trophic Level 4 in the absence of a significant effect at intermediate levels. To the best of my knowledge, this relationship has not been previously reported in a multi‐year or field‐based study of a natural system.
Subterranean aquatic Oligochaeta
Authors: DES CHÂTELLIERS MICHEL CREUZÉ , JUGET JACQUES , LAFONT MICHEL , MARTIN PATRICK
Published: February 2009

1. Aquatic oligochaetes appear to be pre‐adapted to live in the subterranean environment. However, in the absence of genuine troglomorphic characters, the stygobiotic status of groundwater oligochaetes can currently be inferred only from their exclusive presence in the subterranean environment.

2. Aquatic oligochaetes constitute a diverse and mostly endemic fauna. Of the more than 100 species currently considered to be stygobionts, 60% are known only from their type locality. In the Rhône‐Alpes region of France, about 93% of samples taken from caves and galleries were found to contain oligochaetes of which 13 species are classified as stygobionts.

3. Oligochaete biodiversity in aquatic subterranean environments probably originated by both preservation of relict forms and speciationin situ, possibly followed by radiations favoured by heterogeneous and fragmented habitats. Close phylogenetic affinities between some tubificid species from continental waters and the deep sea suggest a marine origin of part of the subterranean oligochaetes.

4. Oligochaetes are well known to promote bioturbation in surface habitats. Similar information on subterranean oligochaetes is scarce, but some evidence suggests notable bioturbation activity also of hypogean species, and they may also play other ecological roles (e.g. as prey and consumers) where present in high densities.

5. Valuable studies to enhance knowledge of subterranean aquatic oligochaetes include continued exploration of a variety of groundwater habitats, phylogeographic surveys that take advantage of molecular methods, analyses of species traits of both stygobiotic and epigean oligochaetes in subterranean environments, and laboratory studies to describe life histories and resolve other aspects of oligochaete biology and ecology.
Temporal discrepancies in the association between the apoB/apoA‐I ratio and mortality in incident dialysis patients
Authors: Chmielewski M. , Carrero J. J. , Qureshi A. R. , Axelsson J. , Heimbürger O. , Berglund L. , Bárány P. , Rutkowski B. , Lindholm B. , Stenvinkel P.
Published: February 2009

Background.  In the general population, a high apoB/apoA‐I ratio is a strong risk factor for cardiovascular disease and mortality. However, whether this is the case in chronic kidney disease (CKD) patients is currently unknown.

Study design.  The apoB/apoA‐I ratio was evaluated in 391 incident CKD stage 5 patients examined close to dialysis initiation, and again after 1 year of dialysis in a subgroup of 182 patients, subsequently followed for up to 3 years.

Results.  Baseline values of the apoB/apoA‐I ratio as well as changes in the ratio during the first year of dialysis correlated with body mass index (BMI) and fat mass. The baseline apoB/apoA‐I ratio showed no association with 4‐year mortality. However, after adjustment for confounders, a high apoB/apoA‐I ratio (>0.9) predicted short‐term (first year) survival [hazard ratio (HR): 0.35; 95% confidence interval (CI): 0.13–0.85)] and long‐term (next 3 years) mortality (HR: 1.72; 95% CI: 1.01–2.96). An increase in the apoB/apoA‐I ratio during the first year of dialysis was linked to a survival advantage thereafter (HR: 0.48; 95% CI: 0.22–0.98). However, this association lost its significance (HR: 0.62; 95% CI: 0.26–1.36) after adjustment for indices of protein‐energy wasting.

Conclusions.  A high apoB/apoA‐I ratio and an increase in this ratio during the first year on dialysis were associated with short‐term survival advantage in CKD patients. This paradoxical relationship represents an example of the so‐called reverse epidemiology phenomenon in CKD patients and suggests that the apoB/apoA‐I ratio should always be interpreted with caution in this patient population.
Plasma folate and total homocysteine levels are associated with the risk of myocardial infarction, independently of each other and of renal function
Authors: Van Guelpen B. , Hultdin J. , Johansson I. , Witthöft C. , Weinehall L. , Eliasson M. , Hallmans G. , Palmqvist R. , Jansson J.‐H. , Winkvist A.
Published: February 2009

Objectives. To investigate the relationship between plasma folate, vitamin B12 and total homocysteine concentrations, dietary intake of folate and vitamins B12, B6 and B2, and the risk of first acute myocardial infarction (MI).

Design. Nested case‐referent study with up to 13 years of follow‐up.

Setting. The population‐based Northern Sweden Health and Disease Study, with 73 879 participants at the time of case ascertainment.

Subjects. A total of 571 MI cases (406 men) and 1569 matched referents. Of the cases, 530 had plasma samples available, and 247 had dietary B‐vitamin intake data.

Results. Plasma concentrations of folate were inversely associated, and total homocysteine positively associated, with the risk of MI, independently of each other and of a number of established and novel cardiovascular risk factors, including renal function [multivariate odds ratio for highest vs. lowest quintile of folate 0.52 (95% CI 0.31–0.84),Pfor trend = 0.036, and homocysteine 1.92 (95% CI 1.20–3.09),Pfor trend = 0.006]. For plasma vitamin B12 concentrations, and vitamin B12, B6 and B2 intake, no clear risk relationship was apparent. Though not statistically significant, the results for folate intake were consistent with those for plasma concentrations.

Conclusions. In this large prospective study of a population without mandatory folic acid fortification, both folate and homocysteine were strongly associated with the risk of myocardial infarction, independently of each other and of renal function. Although randomized trials of folic acid supplementation are needed to determine causality, our findings highlight the potential importance of folate, or sources of folate, in incident cardiovascular disease.
Isotropic high‐resolution three‐dimensional confocal micro‐rotation imaging for non‐adherent living cells
Authors: SAUX B. LE , CHALMOND B. , YU Y. , TROUVÉ A. , RENAUD O. , SHORTE S.L.
Published: February 2009

Recently, micro‐rotation confocal microscopy has enabled the acquisition of a sequence of micro‐rotated images of nonadherent living cells obtained during a partially controlled rotation movement of the cell through the focal plane. Although we are now able to estimate the three‐dimensional position of every optical section with respect to the cell frame, the reconstruction of the cell from the positioned micro‐rotated images remains a last task that this paper addresses. This is not strictly an interpolation problem since a micro‐rotated image is a convoluted two‐dimensional map of a three‐dimensional reality. It is rather a ‘reconstruction from projection’ problem where the term projection is associated to the PSF of the deconvolution process. Micro‐rotation microscopy has a specific difficulty. It does not yield a complete coverage of the volume. In this paper, experiments illustrate the ability of the classical EM algorithm to deconvolve efficiently cell volume despite of the incomplete coverage. This cell reconstruction method is compared to a kernel‐based method of interpolation, which does not take account explicitly the point‐spread‐function (PSF). It is also compared to the standard volume obtained from a conventional z‐stack. Our results suggest that deconvolution of micro‐rotation image series opens some exciting new avenues for further analysis, ultimately laying the way towards establishing an enhanced resolution 3D light microscopy.
Application of electron backscatter diffraction to the study of phase transformations: present and possible future
Authors: GOURGUES‐LORENZON A.‐F.
Published: February 2009

This paper first underlines the main advantages, use and limitations of the electron backscatter diffraction technique from the viewpoint of phase transformations. To get a deeper understanding of physical mechanisms involved in phase transformations, several evolutions are now in progress to get an insight into both three‐dimensional and real‐time information. Two of them, in particular, improvement of data collection versus improvement of data processing are discussed in the second part of this paper.
Effect of annealing temperatures on the secondary re‐crystallization of extruded PM2000 steel bar
Authors: CHEN C.‐L. , TATLOCK G. J. , JONES A.R.
Published: February 2009

The ferritic oxide dispersion‐strengthened alloy PM2000 is an ideal candidate for high‐temperature applications as it contains uniform nano‐oxide dispersoids, which act as pinning points to obstruct dislocation and grain boundary motion and therefore impart excellent creep resistance. The development of the microstructure during re‐crystallization of oxide dispersion‐strengthened alloys has been discussed by a number of authors, but the precise mechanism of secondary re‐crystallization still remains uncertain. Hence, this work is aimed at investigating the re‐crystallization behaviour of extruded PM2000 bar for different annealing temperatures, using electron backscatter diffraction, in particular, to determine grain orientations, grain boundary misorientation angles, etc. The results show that the as‐extruded bar microstructure comprises both low‐angle grain boundaries pinned by oxide particles and high‐angle boundaries that will have inherent boundary mobility to allow boundary migration. In addition, dynamical re‐crystallization was found in the outer region of the non–heat‐treated PM2000 bar, which suggested that deformation heterogeneities can be introduced during thermo‐mechanical processing that enhance the nucleation of re‐crystallization. Subsequent heat treatments promote and stimulate secondary re‐crystallization, giving rise to large grains with few sub‐grain boundaries.
Characterization of cast Al86Mn3Be11 alloy
Authors: BONČINA T. , MARKOLI B. , ZUPANIČ F.
Published: February 2009

An Al86Mn3Be11 alloy cast into copper mould was subjected to metallographic investigation. The as‐cast microstructure consisted of a quasicrystalline icosahedral phase (i‐phase), Be4AlMn phase and, occasionally, a hexagonal phase. Al‐rich solid solution represented the dominant phase. The chemical compositions of phases were determined using AES. The composition of the Be4AlMn slightly deviated from the stoichiometric composition, whereas the composition of the i‐phase was approximately Al52Mn18Be30, containing an appreciable amount of Be. The average composition of the hexagonal phase was Al66Mn21Be13. Deep etching and particle extraction provided a deep insight into the three‐dimensional morphology of the i‐phase and the hexagonal phase, whereas Be4AlMn was slightly attacked by the etchant. The i‐phase was present predominantly in the form of dendrites and a rodlike eutectic phase. The hexagonal phase was primarily in the form of hexagonal platelets, whereas Be4AlMn was rather irregular in shape. The morphology of the i‐phase can be explained by predominant growth in 3‐fold directions and the lowest energy of the 5‐fold planes, leading to the faceting and adopting a pentagonal dodecahedron shape. The brightnesses of phases in the backscattered electron images were rationalized by determining their backscattering coefficients. TEM investigation showed considerable phason strain in the i‐phase, and the polycrystalline nature of the Be4AlMn phase.
Estimating contrast transfer function and associated parameters by constrained non‐linear optimization
Authors: YANG C. , JIANG W. , CHEN D.‐H. , ADIGA U. , NG E.G. , CHIU W.
Published: February 2009

The three‐dimensional reconstruction of macromolecules from two‐dimensional single‐particle electron images requires determination and correction of the contrast transfer function (CTF) and envelope function. A computational algorithm based on constrained non‐linear optimization is developed to estimate the essential parameters in the CTF and envelope function model simultaneously and automatically. The application of this estimation method is demonstrated with focal series images of amorphous carbon film as well as images of ice‐embedded icosahedral virus particles suspended across holes.
Combined EBSD/EDS tomography in a dual‐beam FIB/FEG–SEM
Authors: WEST G.D. , THOMSON R.C.
Published: February 2009

An automated method for collecting combined three‐dimensional (3D) electron backscatter diffraction (EBSD)/energy dispersive spectroscopy (EDS) data sets on a dual‐beam focused ion beam (FIB)/field emission gun scanning electron microscope (FEG–SEM) microscope is described. The method uses simple scripting files on the dual beam to move between the EBSD collection and the FIB slicing positions, which are linked to a commercial EBSD data collection programme. The EDS data are collected simultaneously with the EBSD patterns analogous to combined two‐dimensional (2D) EBSD/EDS. The technique has been successfully applied to study both the interdiffusion zone between a coating and a substrate and a complex multi‐phase coating on a nickel‐based superalloy sample. This analysis is shown to enable the complex grain shapes, location of precipitates and phase interconnectivity within these samples to be determined without the ambiguities associated with 2D stereographic analysis.
Advantages of indium–tin oxide‐coated glass slides in correlative scanning electron microscopy applications of uncoated cultured cells
Authors: PLUK H. , STOKES D.J. , LICH B. , WIERINGA B. , FRANSEN J.
Published: February 2009

A method of direct visualization by correlative scanning electron microscopy (SEM) and fluorescence light microscopy of cell structures of tissue cultured cells grown on conductive glass slides is described. We show that by growing cells on indium–tin oxide (ITO)‐coated glass slides, secondary electron (SE) and backscatter electron (BSE) images of uncoated cells can be obtained in high‐vacuum SEM without charging artefacts. Interestingly, we observed that BSE imaging is influenced by both accelerating voltage and ITO coating thickness. By combining SE and BSE imaging with fluorescence light microscopy imaging, we were able to reveal detailed features of actin cytoskeletal and mitochondrial structures in mouse embryonic fibroblasts. We propose that the application of ITO glass as a substrate for cell culture can easily be extended and offers new opportunities for correlative light and electron microscopy studies of adherently growing cells.
Texture heterogeneities in αp/αs titanium forging analysed by EBSD‐Relation to fatigue crack propagation
Authors: UTA E. , GEY N. , BOCHER P. , HUMBERT M. , GILGERT J.
Published: February 2009

The microstructure and the local texture of a large IMI 834 forging were characterized using the Electron Back Scattered Diffraction (EBSD) technique. Crystallographic domains called macrozones and formed by a majority of primary αp grains with their axes in nearly the same direction were found. They had a band‐like structure, parallel to the axial direction of the forging. The influence of these macrozones on the cold dwell‐fatigue properties was studied. Several samples were tested under cold dwell‐fatigue conditions. The crack initiation and the short‐distance propagation region optically matched a bright region that contained numerous quasi‐cleavage facets. The analysis of the EBSD measurements showed that this bright region was enclosed within a sharp textured region with axes at less than 30° from the loading axis. The crystallographic features of the crack nucleation site and the crack propagation path were also analysed.
Host‐associated speciation in the coral barnacleWanella milleporae(Cirripedia: Pyrgomatidae) inhabiting theMilleporacoral
Authors: TSANG LING MING , CHAN BENNY KWOK KAN , SHIH FU‐LONG , CHU KA HOU , ALLEN CHEN CHAOLUN
Published: February 2009

Speciation by host shift is a common phenomenon observed in many symbiotic animals. The symbiont–host interaction is highly dynamic, but it is poorly documented in the marine realm. In the present study, we examined the genetic and morphological differentiation of the coral barnacleWanella milleporae(obligate to fire corals) collected from four differentMilleporahost species in Taiwan to investigate the host specificity of this barnacle. Phylogenetic analysis of mitochondrial COI gene for 241 individuals ofWanellarevealed five distinct clades, whose sequence divergences are comparable to values between other cogeneric barnacle species. The five clades also differ in shell and opercular plate morphology and colour. Genetic and morphological differentiations together strongly suggest the presence of cryptic species. Although the five clades do not display species‐level host specificity, they showed a significant difference in preference on host growth form. Clades 1 and 2 were predominantly found on encrustingMillepora exaesaandMillepora platyphylla, while clades 3, 4 and 5 live exclusively on branching‐form fire coralsMillepora dichotomaandMillepora tenella. Phylogeny inferred from the combined mitochondrial COI, 16S and 12S (2182 bp) analysis suggests the division of the five clades into two major lineages congruent with the morphology of the host coral. Multiple independent invasions to the same form of host and subsequent speciation are evident in the Red Sea and Taiwan. Our results indicate that ecological/sympatric speciation could occur in marine symbiotic invertebrates through host shift and specialization. It appears that, as in their terrestrial counterparts, host–symbiont radiations in the marine realm are more prevalent than we expected and thus warrant further investigation.
Pedigrees and microsatellites among endangered ungulates: what do they tell us?
Authors: RUIZ‐LÓPEZ MARÍA JOSÉ , ROLDÁN EDUARDO R. S. , ESPESO GERARDO , GOMENDIO MONTSERRAT
Published: February 2009

Relationships between pedigree coefficients of inbreeding and molecular metrics are generally weak, suggesting that measures of heterozygosity estimated using microsatellites may be poor surrogates of genome‐wide inbreeding. We compare three endangered species of gazelles (Gazella) with different degrees of threat in their natural habitats, for which captive breeding programmes exist. For G. dorcas, the species with the largest founding population, the highest and most recent number of founding events, the correlation between pedigree coefficient of inbreeding and molecular metrics was higher than for outbred populations of mammals, probably because it has both higher mean f and variance. For the two species with smaller founding populations, conventional assumptions about founders, i.e. outbred and unrelated, are unrealistic. When realistic assumptions about the founders were made, clear relationships between pedigree coefficients of inbreeding and molecular metrics were revealed for G. cuvieri. This population had a small founding population, but it did experience admixture years later; thus, the relationship between inbreeding and molecular metrics in G. cuvieri is very similar to the expected values but lower than in G. dorcas. In contrast, no relationship was found for G. dama mhorr which had a much smaller founding population than had been previously assumed, which probably had high levels of inbreeding and low levels of genetic variability, and no admixture. In conclusion, the strength of the association between pedigree coefficient of inbreeding and molecular metrics among endangered species depends on the level of inbreeding and genetic variability present in the founding population, its size and its history.
Landscape genetics and least‐cost path analysis reveal unexpected dispersal routes in the California tiger salamander (Ambystoma californiense)
Authors: WANG IAN J. , SAVAGE WESLEY K. , BRADLEY SHAFFER H.
Published: February 2009

A major goal of landscape genetics is to understand how landscapes structure genetic variation in natural populations. However, landscape genetics still lacks a framework for quantifying the effects of landscape features, such as habitat type, on realized gene flow. Here, we present a methodology for identifying the costs of dispersal through different habitats for the California tiger salamander (Ambystoma californiense), an endangered species restricted to grassland/vernal pool habitat mosaics. We sampled larvae from all 16 breeding ponds in a geographically restricted area of vernal pool habitat at the Fort Ord Natural Reserve, Monterey County, California. We estimated between‐pond gene flow using 13 polymorphic microsatellite loci and constructed GIS data layers of habitat types in our study area. We then used least‐cost path analysis to determine the relative costs of movement through each habitat that best match rates of gene flow measured by our genetic data. We identified four measurable rates of gene flow between pairs of ponds, with between 10.5% and 19.9% of larvae having immigrant ancestry. Although A. californiense is typically associated with breeding ponds in grassland habitat, we found that dispersal through grassland is nearly twice as costly as dispersal through chaparral and that oak woodland is by far the most costly habitat to traverse. With the increasing availability of molecular resources and GIS data, we anticipate that these methods could be applied to a broad range of study systems, particularly those with cryptic life histories that make direct observation of movement challenging.
Polyadenylation in Arabidopsis and Chlamydomonas organelles: the input of nucleotidyltransferases, poly(A) polymerases and polynucleotide phosphorylase
Authors: Zimmer Sarah L. , Schein Aleks , Zipor Gadi , Stern David B. , Schuster Gadi
Published: February 2009

The polyadenylation‐stimulated RNA degradation pathway takes place in plant and algal organelles, yet the identities of the enzymes that catalyze the addition of the tails remain to be clarified. In a search for the enzymes responsible for adding poly(A) tails in Chlamydomonas and Arabidopsis organelles, reverse genetic and biochemical approaches were employed. The involvement of candidate enzymes including members of the nucleotidyltransferase (Ntr) family and polynucleotide phosphorylase (PNPase) was examined. For several of the analyzed nuclear‐encoded proteins, mitochondrial localization was established and possible dual targeting to mitochondria and chloroplasts could be predicted. We found that certain members of the Ntr family, when expressed in bacteria, displayed poly(A) polymerase (PAP) activity and partially complemented an Escherichia coli strain lacking the endogenous PAP1 enzyme. Other Ntr proteins appeared to be specific for tRNA maturation. When the expression of PNPase was down‐regulated by RNAi in Chlamydomonas, very few poly(A) tails were detected in chloroplasts for the atpB transcript, suggesting that this enzyme may be solely responsible for chloroplast polyadenylation activity in this species. Depletion of PNPase did not affect the number or sequence of mitochondrial mRNA poly(A) tails, where unexpectedly we found, in addition to polyadenylation, poly(U)‐rich tails. Together, our results identify several Ntr‐PAPs and PNPase in organelle polyadenylation, and reveal novel poly(U)‐rich sequences in Chlamydomonas mitochondria.
Characterization of selenocysteine methyltransferases from Astragalus species with contrasting selenium accumulation capacity
Authors: Sors Thomas G. , Martin Catherine P. , Salt David E.
Published: February 2009

A group of selenium (Se)‐hyperaccumulating species belonging to the genus Astragalus are known for their capacity to accumulate up to 0.6% of their foliar dry weight as Se, with most of this Se being in the form of Se‐methylselenocysteine (MeSeCys). Here, we report the isolation and molecular characterization of the gene that encodes a putative selenocysteine methyltransferase (SMT) enzyme from the non‐accumulator Astragalus drummondii and biochemically compare it with an authentic SMT enzyme from the Se‐hyperaccumulator Astragalus bisulcatus, a related species that lives within the same native habitat. The non‐accumulator enzyme (AdSMT) shows a high degree of homology with the accumulator enzyme (AbSMT) but lacks the selenocysteine methyltransferase activity in vitro, explaining why little or no detectable levels of MeSeCys accumulation are observed in the non‐accumulator plant. The insertion of mutations on the coding region of the non‐accumulator AdSMT enzyme to better resemble enzymes that originate from Se accumulator species results in increased selenocysteine methyltransferase activity, but these mutations were not sufficient to fully gain the activity observed in the AbSMT accumulator enzyme. We demonstrate that SMT is localized predominantly within the chloroplast in Astragalus, the principal site of Se assimilation in plants. By using a site‐directed mutagenesis approach, we show that an Ala to Thr amino acid mutation at the predicted active site of AbSMT results in a new enzymatic capacity to methylate homocysteine. The mutated AbSMT enzyme exhibited a sixfold higher capacity to methylate selenocysteine, thereby establishing the evolutionary relationship of SMT and homocysteine methyltransferase enzymes in plants.
Functional expression and characterization of Arabidopsis ABCB, AUX 1 and PIN auxin transporters in Schizosaccharomyces pombe
Authors: Yang Haibing , Murphy Angus S.
Published: February 2009

Heterologous expression systems based on tobacco BY‐2 cells, Arabidopsis cell cultures, Xenopus oocytes, Saccharomyces cerevisiae, and human HeLa cells have been used to express and characterize PIN, ABCB (PGP), and AUX/LAX auxin transporters from Arabidopsis. However, no single system has been identified that can be used for effective comparative analyses of these proteins. We have developed an accessible Schizosaccharomyces pombe system for comparative studies of plant transport proteins. The system includes knockout mutants in all ABC and putative auxin transport genes and Gateway®‐compatible expression vectors for functional analysis and subcellular localization of recombinant proteins. We expressed Arabidopsis ABCB1 and ABCB19 in mam1pdr1 host lines under the inducible nmt41 promoter. ABCB19 showed a higher 3H‐IAA export activity than ABCB1. Arabidopsis PIN proteins were expressed in a mutant lacking the auxin effluxer like 1 (AEL1) gene. PIN1 showed higher activity than PIN2 with similar protein expression levels. Expression of AUX1 in a permease‐deficient vat3 mutant resulted in increased net auxin uptake activity. Finally, ABCB4 expressed in mam1pdr1 displayed a concentration‐dependent reversal of 3H‐IAA transport that is consistent with its observed activity in planta. Structural modelling suggests that ABCB4 has three substrate interaction sites rather than the two found in ABCB19, thus providing a rationale for the observed substrate activation. Taken together, these results suggest that the S. pombe system described here can be employed for comparative analyses and subsequent structural characterizations of plant transport proteins.
Colorectal cancer patients’ attitudes towards involvement in decision making
Authors: Beaver Kinta , Campbell Malcolm , Craven Olive , Jones David , Luker Karen A. , Susnerwala Shabbir S.
Published: February 2009

Objectives  To design and administer an attitude rating scale, exploring colorectal cancer patients’ views of involvement in decision making. To examine the impact of socio‐demographic and/or treatment‐related factors on decision making. To conduct principal components analysis to determine if the scale could be simplified into a number of factors for future clinical utility.

Methods  An attitude rating scale was constructed based on previous qualitative work and administered to colorectal cancer patients using a cross‐sectional survey approach.

Results  375 questionnaires were returned (81.7% response). For patients it was important to be informed and involved in the decision‐making process. Information was not always used to make decisions as patients placed their trust in medical expertise. Women had more positive opinions on decision making and were more likely to want to make decisions. Written information was understood to a greater degree than verbal information. The scale could be simplified to a number of factors, indicating clinical utility.

Conclusion  Few studies have explored the attitudes of colorectal cancer patients towards involvement in decision making. This study presents new insights into how patients view the concept of participation; important when considering current policy imperatives in the UK of involving service users in all aspects of care and treatment.
Choosing between CT colonography and colonoscopy in the diagnostic context: a qualitative study of influences on patient preferences
Authors: Von Wagner Christian , Halligan Steve , Atkin Wendy S. , Lilford Richard J. , Morton Dion , Wardle Jane
Published: February 2009

Objective  To explore information needs and preferences on diagnostic bowel tests and elicit preferences for CT colonography (CTC) vs. colonoscopy (CC).

Background  CTC is a new technology for large‐bowel imaging that has been widely assumed to be more acceptable than CC because it is non‐invasive.

Design  Semi‐structured focus groups discussing information choices and procedure preferences.

Setting and participants  Non‐patient sample of 26 asymptomatic volunteers (mean age 64 years).

Main outcome measures  Information choices and CC‐vs.‐CTC preferences were recorded following stepwise presentation of different test attributes. Qualitative thematic analysis was used to examine transcripts of group discussions.

Results  On the basis of minimal information about the two tests, a majority of participants preferred CTC to CC (65% vs. 11%), while 24% had no preference. However, once they had received information on all aspects, this was reversed, with 80% of participants preferring CC compared with 8% preferring CTC. Thematic analysis of the discussion showed that participants almost unanimously considered information about test sensitivity to be the most important feature, and perceived relatively modest differences in test sensitivity to be highly significant. Information about risks and side‐effects was considered to be the second most important aspect and attracted questions about risks of bowel perforation and health consequences following exposure to radiation.

Conclusions  Patients place high value on quality rather than comfort for medical investigations. This has important implications for the development of educational materials supporting informed choice as well as future directions in refinement of CTC technology.
A treatment decision aid may increase patient trust in the diabetes specialist. The Statin Choice randomized trial
Authors: Nannenga Michael R. , Montori Victor M. , Weymiller Audrey J. , Smith Steven A. , Christianson Teresa J. H. , Bryant Sandra C. , Gafni Amiram , Charles Cathy , Mullan Rebecca J. , Jones Lesley A. , Bolona Enrique R. , Guyatt Gordon H.
Published: February 2009

Aims  Decision aids in practice may affect patient trust in the clinician, a requirement for optimal diabetes care. We sought to determine the impact of a decision aid to help patients with diabetes decide about statins (Statin Choice) on patients’ trust in the clinician.

Methods  We randomized 16 diabetologists and 98 patients with type 2 diabetes referred to a subspecialty diabetes clinic to use the Statin Choice decision aid or a patient pamphlet about dyslipidaemia, and then to receive these materials from either the clinician during the visit or a researcher prior to the visit. Providers and patients were blinded to the study hypothesis. Immediately after the clinical encounter, patients completed a survey including questions on trust (range 0 to total trust = 100), knowledge, and decisional conflict. Researchers reviewed videotaped encounters and assessed patient participation (using the OPTION scale) and visit length.

Results  Overall mean trust score was 91 (median 97.2, IQR 86, 100). After adjustment for patient characteristics, results suggested greater total trust (trust = 100) with the decision aid [odds ratio (OR) 1.77, 95% CI 0.94, 3.35]. Total trust was associated with knowledge (for each additional knowledge point, OR 1.3, 95% CI 1.1, 1.6), patient participation (for each additional point in the OPTION scale, OR 1.1, 95% CI 1.1, 1.2), and decisional conflict (for every 5‐point decrease in conflict, OR 1.5, 95% CI 1.2, 1.9). Total trust was not associated with visit length, which the decision aid did not significantly affect. There was no significant effect interaction across the trial factors.

Conclusions  Preliminary evidence suggests that decision aids do not have a large negative impact on trust in the physician and may increase trust through improvements in the decision‐making process.
Lay perceptions of the desired role and type of user involvement in clinical governance
Authors: Litva Andrea , Canvin Krysia , Shepherd Michael , Jacoby Ann , Gabbay Mark
Published: February 2009

Objective  The aim of this paper is to explore variations in lay perceptions of user involvement in clinical governance.

Context  The English National Health Service has sought to build a dependable health service through enhanced effectiveness, responsiveness and consistency. Clinical governance, a policy for improving service quality, is a key pillar of these reforms. It is a statutory duty of primary care organizations to ensure that users are involved in all service planning and decision making, including clinical governance. Yet surveys indicated that user involvement in clinical governance was underdeveloped and underutilized.

Design  Focus groups were conducted with different types of lay people to explore their perceptions around public involvement in different aspects of clinical governance policy.

Results  Content analysis of the transcripts reveals that different groups of lay people varied in their desired role perspective and preferred type of involvement in different aspects of clinical governance policy. Drawing upon existing models of user involvement, we identified three role perspectives that lay people could take in user involvement – consumer, advocate and citizen. We compared our findings regarding the desired type of involvement with existing models of user involvement, and identified a new type of involvement, overseeing, that is relevant to clinical governance policy.

Conclusions  These findings suggest that to facilitate user involvement in clinical governance, it would be necessary to use different strategies to accommodate the differing role perspectives and types of involvement desired by different groups of lay people.
Long‐lasting allergic contact blepharoconjunctivitis to phenylephrine eyedrops
Authors: Raison‐Peyron N. , Du Thanh A. , Demoly P. , Guillot B.
Published: February 2009

Allergic contact dermatitis due to mydriatic eyedrops is rare despite extensively used by ophthalmologists. Phenylephrine is responsible for most of the cases in the literature. We reported two other cases due to phenylephrine eyedrops with an unusual evolution characterized by chronic debilitating blepharoconjunctivitis.