bluuebunny/crossref_metadata_2025 huggingface dataset:
Barcoding deep-water chondrichthyans from mainland Portugal
Authors: Moura T. , Silva M. C. , Figueiredo I.
Published: January 2015

Most deep-water chondrichthyans occurring off mainland Portugal are distributed worldwide. There are many closely related species with similar morphology, and the lack of diagnostic characters that unambiguously allow species discrimination has led to extensive identification problems. Here, DNA barcodes were used to evaluate the suitability of cytochrome c oxidase I (COI) to identify deep-water chondrichthyans and to further contribute to the worldwide molecular databases currently in use. The sample was composed of 40 individuals from the families Chimaeridae, Centrophoridae, Somniosidae, Etmopteridae, Oxynotidae, Dalatiidae, Scyliorhinidae, Mitsukurinidae, Chlamydoselachidae and Hexanchidae. COI proved to be adequate for species identification, with almost all putative species recovered as well supported monophyletic clades, with low intraspecific variation. Sequence matches against the BOLD database provided evidence for the existence of identification problems particularly within the genera Hydrolagus, Galeus and Centrophorus. Present results suggest that three different Centrophorus species occur off the Portuguese mainland, C. squamosus, C. granulosus and C. uyato. The sample also included an albino Deania calcea and a C. squamosus specimen without dermal denticles. This study updates the current knowledge on diversity and distribution of deep-water chondrichthyans occurring along the Portuguese coast, and provides an essential tool for species identification and consistency of taxonomic designations worldwide.
Modelling canopy fuel dynamics of maritime pine stands in north-west Spain
Authors: Ruiz-González Ana Daría , Castedo-Dorado Fernando , Vega José Antonio , Jiménez Enrique , Fernández-Alonso José María , Álvarez-González Juan Gabriel
Published: January 2015

Effective silvicultural strategies for reducing the likelihood and severity of crown fires include increasing canopy base height (CBH) and reducing canopy bulk density (CBD). These variables depend to a certain degree on stand structure and are therefore responsive to stand density management through thinning. In this study, data from permanent sample plots and thinning trials were used to model the dynamics of canopy fuel variables in maritime pine stands in north-western Spain. On the basis of the state–space modelling approach, the canopy fuel conditions at any point in time were assumed to be adequately defined by three state variables: number of stems per hectare (N), canopy fuel load (CFL) and CBH. These variables were projected by simultaneous fitting of three transition functions, which explained more than 77, 96 and 97% of the observed variability in N, CFL and CBH. The effect of thinning was modelled by including a thinning response function. Once the state variables were determined for a given point in time, CBD was derived from CFL, CBH and average stand height, thus ensuring compatibility between estimates. The system of equations developed, together with fire management decision support systems, will enable assessment of the crown fire potential associated with different silvicultural alternatives.
Ambivalent sexism and egalitarian ideology in perception of psychological abuse and (in)vulnerability to violence / Sexismo ambivalente e ideología igualitaria en la percepción del maltrato psicológico y la (in)vulnerabilidad a la violencia
Authors: Marques-Fagundes Ana-Luisa , Megías Jesús L. , García-García Daniela Mͣ , Petkanopoulou Katerina
Published: January 2015

Psychological violence against women in intimate relations is one of the most widespread and hidden ways of limiting their human rights. Nowadays different ideologies, including sexism and feminism, can contribute to (dis)regard this phenomenon. This study focuses on the relationship between ambivalent sexism (in its hostile and benevolent dimensions) and feminism (in the egalitarian ideology dimension) with the identification of psychological violence and the perception of invulnerability to the intimate partner violence in women. The mediator role of the myths about gender-based violence in these relationships is analysed. Participants were 91 women, with heterogeneous socio-demographic characteristics. Results showed benevolent sexism as a risk factor and egalitarian feminism ideology as a protector factor in the process of the perception of psychological violence. The egalitarian feminism ideology also appears as the main predictor of the perception of invulnerability to abuse. This relationship is mediated by the degree of adhesion to the myths about gender-based violence. These findings reinforce the importance of the attitudinal and ideological factors in the perception of gender-based violence.
Violence and democracy in South Africa's community protests
Authors: Paret Marcel
Published: January 2015

Community protests in South Africa are often described as violent. Drawing from newspaper articles, interviews with protesters and statements by public officials, this paper unpacks the meaning of ‘violent protest'. It shows that violence is both ambiguous and deeply entangled with democracy. On the one hand, violent practices may become a tool of liberation, promoting democracy by empowering marginalised groups. On the other hand, democracy may become a tool of domination, undermining dissent by constituting as violent those persons and actions that deviate from formal institutional channels. The analysis urges scholars to adopt a critical and nuanced view of violence.
The 42nd Sir Frederic Bartlett Lecture
Authors: Logan Gordon D.
Published: January 2015

Bartlett (1958. Thinking. New York: Basic Books) described the point of no return as a point of irrevocable commitment to action, which was preceded by a period of gradually increasing commitment. As such, the point of no return reflects a fundamental limit on the ability to control thought and action. I review the literature on the point of no return, taking three perspectives. First, I consider the point of no return from the perspective of the controlled act, as a locus in the architecture and anatomy of the underlying processes. I review experiments from the stop-signal paradigm that suggest that the point of no return is located late in the response system. Then I consider the point of no return from the perspective of the act of control that tries to change the controlled act before it becomes irrevocable. From this perspective, the point of no return is a point in time that provides enough “lead time” for the act of control to take effect. I review experiments that measure the response time to the stop signal as the lead time required for response inhibition in the stop-signal paradigm. Finally, I consider the point of no return in hierarchically controlled tasks, in which there may be many points of no return at different levels of the hierarchy. I review experiments on skilled typing that suggest different points of no return for the commands that determine what is typed and the countermands that inhibit typing, with increasing commitment to action the lower the level in the hierarchy. I end by considering the point of no return in perception and thought as well as action.
𝐿²-Betti numbers of locally compact groups and their cross section equivalence relations
Authors: Kyed David , Petersen Henrik , Vaes Stefaan
Published: January 2015

We prove that the

L
2

L^2

-Betti numbers of a unimodular locally compact group

G
G

coincide, up to a natural scaling constant, with the

L
2

L^2

-Betti numbers of the countable equivalence relation induced on a cross section of any essentially free ergodic probability measure preserving action of

G
G

. As a consequence, we obtain that the reduced and unreduced

L
2

L^2

-Betti numbers of

G
G

agree and that the

L
2

L^2

-Betti numbers of a lattice

Γ
\Gamma

in

G
G

equal those of

G
G

up to scaling by the covolume of

Γ
\Gamma

in

G
G

. We also deduce several vanishing results, including the vanishing of the reduced

L
2

L^2

-cohomology for amenable locally compact groups.
On the blowup and lifespan of smooth solutions to a class of 2-D nonlinear wave equations with small initial data
Authors: Jun Li , Witt Ingo , Huicheng Yin
Published: January 2015

We are concerned with a class of two-dimensional nonlinear wave equations

∂
t
2

u
−
div
(

c
2

(
u
)
∇
u
)
=
0

\partial _t^2u-\text {div}(c^2(u)\nabla u)=0

or

∂
t
2

u
−
c
(
u
)

d
i
v

(
c
(
u
)
∇
u
)
=
0

\partial _t^2u-c(u)\mathrm {div}(c(u)\nabla u)=0

with small initial data
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="left-parenthesis u left-parenthesis 0 comma x right-parenthesis comma partial-differential Subscript t Baseline u left-parenthesis 0 comma x right-parenthesis right-parenthesis equals left-parenthesis epsilon u 0 left-parenthesis x right-parenthesis comma epsilon u 1 left-parenthesis x right-parenthesis right-parenthesis">

(
u
(
0
,
x
)
,

∂
t

u
(
0
,
x
)
)
=
(
ε

u
0

(
x
)
,
ε

u
1

(
x
)
)

(u(0,x), \partial _tu(0,x))=(\varepsilon u_0(x), \varepsilon u_1(x))

, where

c
(
u
)

c(u)

is a smooth function,

c
(
0
)
≠
0

c(0)\not =0

,

x
∈

R

2

x\in \mathbb R^2

,

u
0

(
x
)
,

u
1

(
x
)
∈

C
0

∞

(

R

2

)

u_0(x), u_1(x)\in C_0^{\infty }(\mathbb R^2)

depend only on

r
=

x
1
2

+

x
2
2

r=\sqrt {x_1^2+x_2^2}

, and

ε
>
0

\varepsilon >0

is sufficiently small. Such equations arise in a pressure-gradient model of fluid dynamics, as well as in a liquid crystal model or other variational wave equations. When

c
′

(
0
)
≠
0

c’(0)\not = 0

or

c
′

(
0
)
=
0

c’(0)=0

,

c
(
0
)
≠
0

c(0)\not = 0

, we establish blowup and determine the lifespan of smooth solutions.
The inverse problem for universal deformation rings and the special linear group
Authors: Dorobisz Krzysztof
Published: January 2015

We present a solution to the inverse problem for universal deformation rings of group representations. Namely, we show that every complete noetherian local commutative ring

R
R

with a finite residue field

k
k

can be realized as the universal deformation ring of a continuous linear representation of a profinite group. More specifically,

R
R

is the universal deformation ring of the natural representation of

S
L

n

(
R
)

\mathrm {SL}_n(R)

in

S
L

n

(
k
)

\mathrm {SL}_n(k)

, provided that

n
≥
4

n\geq 4

. We also check for which

R
R

an analogous result is true in case

n
=
2

n=2

and

n
=
3

n=3

.
A statistical anomaly indicates symbiotic origins of eukaryotic membranes
Authors: Bansal Suneyna , Mittal Aditya
Published: January 2015

Compositional analyses of nucleic acids and proteins have shed light on possible origins of living cells. In this work, rigorous compositional analyses of ∼5000 plasma membrane lipid constituents of 273 species in the three life domains (archaea, eubacteria, and eukaryotes) revealed a remarkable statistical paradox, indicating symbiotic origins of eukaryotic cells involving eubacteria. For lipids common to plasma membranes of the three domains, the number of carbon atoms in eubacteria was found to be similar to that in eukaryotes. However, mutually exclusive subsets of same data show exactly the opposite—the number of carbon atoms in lipids of eukaryotes was higher than in eubacteria. This statistical paradox, called Simpson's paradox, was absent for lipids in archaea and for lipids not common to plasma membranes of the three domains. This indicates the presence of interaction(s) and/or association(s) in lipids forming plasma membranes of eubacteria and eukaryotes but not for those in archaea. Further inspection of membrane lipid structures affecting physicochemical properties of plasma membranes provides the first evidence (to our knowledge) on the symbiotic origins of eukaryotic cells based on the “third front” (i.e., lipids) in addition to the growing compositional data from nucleic acids and proteins.
Size-dependent leak of soluble and membrane proteins through the yeast nuclear pore complex
Authors: Popken Petra , Ghavami Ali , Onck Patrick R. , Poolman Bert , Veenhoff Liesbeth M.
Published: January 2015

Nuclear pore complexes (NPCs) allow selective import and export while forming a barrier for untargeted proteins. Using fluorescence microscopy, we measured in vivo the permeability of the Saccharomyces cerevisiae NPC for multidomain proteins of different sizes and found that soluble proteins of 150 kDa and membrane proteins with an extralumenal domain of 90 kDa were still partly localized in the nucleus on a time scale of hours. The NPCs thus form only a weak barrier for the majority of yeast proteins, given their monomeric size. Using FGΔ-mutant strains, we showed that specific combinations of Nups, especially with Nup100, but not the total mass of FG-nups per pore, were important for forming the barrier. Models of the disordered phase of wild-type and mutant NPCs were generated using a one bead per amino acid molecular dynamics model. The permeability measurements correlated with the density predictions from coarse-grained molecular dynamics simulations in the center of the NPC. The combined in vivo and computational approach provides a framework for elucidating the structural and functional properties of the permeability barrier of nuclear pore complexes.
Longitudinal Clinical Findings and Outcome Among Patients With Cryptococcus gattii Infection in British Columbia
Authors: Phillips Peter , Galanis Eleni , MacDougall Laura , Chong Mei Y. , Balshaw Robert , Cook Victoria J. , Bowie William , Steiner Theodore , Hoang Linda , Morshed Muhammad , Ghesquiere Wayne , Forrest David M. , Roscoe Diane , Doyle Patrick , Kibsey Pamela C. , Connolly Thomas , Mirzanejad Yazdan , Thompson Darby ,   for the British Columbia Cryptococcus gattii Study Group, Saliken John , Sanders Bruce , Partlow Eric , Vortel Jerry , Arikan Yasmin , Fyfe Murray
Published: January 2015

Background.  Cryptococcus gattii (Cg) infection emerged in British Columbia in 1999. A longitudinal, clinical description of patients has not been reported.

Methods.  Medical records were reviewed for Cg patients identified through surveillance (1999–2007). Risk factors for Cg mortality were explored using multivariate Cox regression; longitudinal patterns in serum cryptococcal antigen (SCrAg) titers and the probability of chest cryptococcomas over time were estimated using cubic B-splines in mixed-effects regression models.

Results.  Among 152 patients, 111 (73.0%) were culture confirmed. Isolated lung infection was present in 105 (69.1%) patients; 47 (30.9%) had central nervous system infection, with or without lung involvement. Malignancy was the provisional diagnosis in 64 (42.1%) patients. Underlying diseases were present in 91 (59.9%) patients; 23 (15.1%) were immunocompromised, and 23 (15.1%) had asymptomatic disease. There were only 2 (1.8%) culture positive relapses, both within 12 months of follow-up. The estimated median time to resolution of lung cryptococcomas and decline in SCrAg titer to <1:8 was 2.8 and 2.9 years, respectively. Cg-related and all-cause mortality among culture-confirmed cases at 12 months’ follow-up was 23.3% and 27.2%, respectively. Cg-related mortality was associated with age >50 years (hazard ratio [HR], 15.6; 95% confidence interval [CI], 1.9–130.5) and immunocompromise (HR, 5.8; CI, 1.5–21.6). All Cg-related mortality occurred among culture-positive cases within 1 year of diagnosis.

Conclusions.  Cryptococcomas and serum antigenemia were slow to resolve. However, late onset of failed therapy or relapse was uncommon, suggesting that delayed resolution of these findings does not require prolongation of treatment beyond that recommended by guidelines.
Identification and properties of plasma membrane azole efflux pumps from the pathogenic fungi Cryptococcus gattii and Cryptococcus neoformans
Authors: Basso Luiz R. , Gast Charles E. , Bruzual Igor , Wong Brian
Published: January 2015

Objectives

Cryptococcus gattii from the North American Northwest (NW) have higher azole MICs than do non-NW C. gattii or Cryptococcus neoformans. Since mechanisms of azole resistance in C. gattii are not known, we identified C. gattii and C. neoformans plasma membrane azole efflux pumps and characterized their properties.

Methods

The C. gattii R265 genome was searched for orthologues of known fungal azole efflux genes, expression of candidate genes was assessed by RT–PCR and the expressed genes' cDNAs were cloned and expressed in Saccharomyces cerevisiae. Azole MICs and intracellular [3H]fluconazole were measured in C. gattii and C. neoformans and in S. cerevisiae expressing each cDNA of interest, as was [3H]fluconazole uptake by post-Golgi vesicles (PGVs) isolated from S. cerevisiae sec6-4 mutants expressing each cDNA of interest.

Results

Intracellular [3H]fluconazole concentrations were inversely correlated with fluconazole MICs only in 25 NW C. gattii strains. S. cerevisiae expressing three C. gattii cDNAs (encoded by orthologues of C. neoformans AFR1 and MDR1 and the previously unstudied gene AFR2) and their C. neoformans counterparts had higher azole MICs and lower intracellular [3H]fluconazole concentrations than did empty-vector controls. PGVs from S. cerevisiae expressing all six Cryptococcus cDNAs also accumulated more [3H]fluconazole than did controls, and [3H]fluconazole transport by all six transporters of interest was ATP dependent and was inhibited by excess unlabelled fluconazole, voriconazole, itraconazole and posaconazole.

Conclusions

We conclude that C. gattii and C. neoformans AFR1, MDR1 and AFR2 encode ABC transporters that pump multiple azoles out of S. cerevisiae cells, thereby causing azole resistance.
Antibiotics: the changing regulatory and pharmaceutical industry paradigm
Authors: Bax Richard , Green Samantha
Published: January 2015

Drug licensing is changing. Previously, regulators prioritized the licensing of innovative drugs that fulfilled a high unmet medical need for a small number of patients, including orphan, cancer and HIV medicines. Alternatives to large and costly prospective, randomized, double-blind clinical trials have led to a more bespoke development, such as adaptive design studies. Regulators have recently agreed to include much-needed narrow-spectrum antibiotics, active against certain MDR bacteria, in this paradigm. The background to why big pharmaceutical companies have largely deserted the antibacterial research arena, and the proposals that are hoped to reinvigorate their interest, are presented.
A multi-transition study of molecules toward NGC 1068 based on high-resolution imaging observations with ALMA
Authors: Nakajima Taku , Takano Shuro , Kohno Kotaro , Harada Nanase , Herbst Eric , Tamura Yoichi , Izumi Takuma , Taniguchi Akio , Tosaki Tomoka
Published: January 2015

We present 0.8-mm band molecular images and spectra obtained with the Atacama Large Millimeter/submillimeter Array (ALMA) toward one of the nearest galaxies with an active galactic nucleus (AGN), NGC 1068. Distributions of CO isotopic species (13CO and C18O) J = 3–2, CN N = 3–2, and CS J = 7–6 are observed toward the circumnuclear disk (CND) and a part of the starburst ring with an angular resolution of ∼ 1${^{\prime\prime}_{.}}$3 × 1${^{\prime\prime}_{.}}$2. The physical properties of these molecules and shock-related molecules, such as HNCO, CH3CN, SO, and CH3OH, detected in the 3-mm band were estimated using rotation diagrams under the assumption of local thermodynamic equilibrium. The rotational temperatures of the CO isotopic species and the shock-related molecules in the CND are, respectively, 14–22 K and upper limits of 20–40 K. Although the column densities of the CO isotopic species in the CND are only from one-fifth to one-third of that in the starburst ring, those of the shock-related molecules are enhanced by a factor of 3–10 in the CND. We also discuss the chemistry of each species, and compare the fractional abundances in the CND and starburst ring with those of Galactic sources such as cold cores, hot cores, and shocked molecular clouds in order to study the overall characteristics. We find that the abundances of shock-related molecules are more similar to abundances in hot cores and/or shocked clouds than to cold cores. The CND hosts relatively complex molecules, which are often associated with shocked molecular clouds or hot cores. Because a high X-ray flux can dissociate these molecules, they must also reside in regions shielded from X-rays.
Oral Reduced L‐Glutathione Improves Growth in Pediatric Cystic Fibrosis Patients
Authors: Visca Alfredo , Bishop Clark T. , Hilton Sterling , Hudson Valerie M.
Published: January 2015

Background and Objective:

Consensus nutritional guidelines for patients with cystic fibrosis (CF) recommend aggressive treatment of growth failure. Oral reduced glutathione (GSH) has been shown to improve cachexia and case reports have demonstrated improved growth in pediatric patients with CF. No controlled studies using oral GSH in CF have, however, been reported. The aim of the study was to determine whether oral GSH could improve growth in CF. Secondarily, to determine whether oral GSH could improve other systemic clinical markers.

Methods:

We performed a placebo‐controlled, randomized, double‐blind, repeated‐measures clinical trial in 44 pediatric patients with CF ages 18 months to 10 years. Primary outcomes were change in weight percentile, body mass index (BMI) percentile, height percentile, and fecal calprotectin. Secondary outcomes included liver function tests and measures of systemic inflammation. Each participant was studied for 6 months, with data obtained at baseline, 3 months, and 6 months. Blood samples were obtained on the baseline and 6‐month visits. Subjects were treated with oral GSH or placebo (calcium citrate), each 65 mg · kg−1 · day−1 divided into 3 doses per day at mealtimes, and administered daily for 6 months.

Results:

The GSH treatment group gained an average of 0.67 standard deviation (SD) in weight‐for‐age‐and sex z score (wfaszs), (19.1 weight percentile points) during the course of 6 months, with no adverse effects (vs placebo with an increase of 0.1 SD in wfaszs [2.1 weight percentile points], P < 0.0001). Fecal calprotectin improved, GSH −52.0 vs placebo 0.5), also BMI for GSH improved 0.69 SD BMI‐adjusted‐for‐age‐and‐sex z score versus placebo 0.22 SD (BMI percentile 21.7 GSH vs 5.2 placebo), and height 0.2 SD in height‐for‐age‐and‐sex z score (hfaszs) GSH versus −0.06 SD hfaszs placebo [height percentile 7.0 GSH vs −2.6 placebo], all P < 0.0001). Secondary outcomes improved significantly, as well.

Conclusions:

Oral reduced L‐GSH significantly improves measures of growth status and gut inflammation in CF.
Female signalling to male song in the domestic canary,
Serinus canaria
Authors: Amy Mathieu , Salvin Pauline , Naguib Marc , Leboucher Gerard
Published: January 2015

Most studies on sexual selection focus on male characteristics such as male song in songbirds. Yet female vocalizations in songbirds are growing in interest among behavioural and evolutionary biologists because these vocalizations can reveal the female's preferences for male traits and may affect male display. This study was designed to test whether male song performance influences the different female signals in the domestic canary (
Serinus canaria
). Female canaries were exposed to three types of song performance, differing in the repetition rate of sexy syllables. This experiment demonstrates that female birds are engaged in multimodal communication during sexual interaction. The results support the copulation solicitation hypothesis for female-specific trills: these trills were positively correlated and had a similar pattern to the copulation solicitation displays; responses were higher to the songs with higher performance and responses decreased with the repetition of the stimulation. Also, we observed a sensitization effect with the repetition of the song of the highest performance for the simple calls. Simple trills and other calls were more frequent during the broadcast of canary songs compared with the heterospecific control songs. The differential use of female signals in response to different song performance reveals a highly differentiated female signalling system which is discussed in light of the role of female traits to understand sexual selection in a broader perspective.
Perturbation of Maize Phenylpropanoid Metabolism by an AvrE Family Type III Effector fromPantoea stewartii
Authors: Asselin Jo Ann E. , Lin Jinshan , Perez-Quintero Alvaro L. , Gentzel Irene , Majerczak Doris , Opiyo Stephen O. , Zhao Wanying , Paek Seung-Mann , Kim Min Gab , Coplin David L. , Blakeslee Joshua J. , Mackey David
Published: January 2015

AvrE family type III effector proteins share the ability to suppress host defenses, induce disease-associated cell death, and promote bacterial growth. However, despite widespread contributions to numerous bacterial diseases in agriculturally important plants, the mode of action of these effectors remains largely unknown. WtsE is an AvrE family member required for the ability of Pantoea stewartii ssp. stewartii (Pnss) to proliferate efficiently and cause wilt and leaf blight symptoms in maize (Zea mays) plants. Notably, when WtsE is delivered by a heterologous system into the leaf cells of susceptible maize seedlings, it alone produces water-soaked disease symptoms reminiscent of those produced by Pnss. Thus, WtsE is a pathogenicity and virulence factor in maize, and an Escherichia coli heterologous delivery system can be used to study the activity of WtsE in isolation from other factors produced by Pnss. Transcriptional profiling of maize revealed the effects of WtsE, including induction of genes involved in secondary metabolism and suppression of genes involved in photosynthesis. Targeted metabolite quantification revealed that WtsE perturbs maize metabolism, including the induction of coumaroyl tyramine. The ability of mutant WtsE derivatives to elicit transcriptional and metabolic changes in susceptible maize seedlings correlated with their ability to promote disease. Furthermore, chemical inhibitors that block metabolic flux into the phenylpropanoid pathways targeted by WtsE also disrupted the pathogenicity and virulence activity of WtsE. While numerous metabolites produced downstream of the shikimate pathway are known to promote plant defense, our results indicate that misregulated induction of phenylpropanoid metabolism also can be used to promote pathogen virulence.
A new parallel and GPU version of aTREOR-based algorithm for indexing powder diffraction data
Authors: Šimeček Ivan , Rohlíček Jan , Zahradnický Tomáš , Langr Daniel
Published: January 2015

One of the key parts of the crystal structure solution process from powder diffraction data is indexing – the determination of the lattice parameters from experimental data. This paper presents a modification of theTREORindexing method that makes the algorithm suitable and efficient for execution on graphics processing units. TheTREORalgorithm was implemented in its pure form, which can be simply described as a `brute-force' approach. The effectiveness and time consumption of such an algorithm was tested on several data sets including monoclinic and triclinic examples. The results show the potential of using GPUs for indexing powder diffraction data.
A generalized geometric approach to anisotropic peak broadening due to domain morphology
Authors: Ectors D. , Goetz-Neunhoeffer F. , Neubauer J.
Published: January 2015

This article reports the derivation of a physically based geometric description of the mean diameter of orthogonal shapes and provides an efficient formalism to relate these to reciprocal lattices and corresponding apparent crystallite sizes. The following descriptions provide a reasonable approximation for the simulation and refinement of anisotropic domain morphology in powder diffraction techniques.
A microfabricated fixed path length silicon sample holder improves background subtraction for cryoSAXS
Authors: Hopkins Jesse B. , Katz Andrea M. , Meisburger Steve P. , Warkentin Matthew A. , Thorne Robert E. , Pollack Lois
Published: January 2015

The application of small-angle X-ray scattering (SAXS) for high-throughput characterization of biological macromolecules in solution is limited by radiation damage. By cryocooling samples, radiation damage and required sample volumes can be reduced by orders of magnitude. However, the challenges of reproducibly creating the identically sized vitrified samples necessary for conventional background subtraction limit the widespread adoption of this method. Fixed path length silicon sample holders for cryoSAXS have been microfabricated to address these challenges. They have low background scattering and X-ray absorption, require only 640 nl of sample, and allow reproducible sample cooling. Data collected in the sample holders from a nominal illuminated sample volume of 2.5 nl are reproducible down toq≃ 0.02 Å−1, agree with previous cryoSAXS work and are of sufficient quality for reconstructions that match measured crystal structures. These sample holders thus allow faster, more routine cryoSAXS data collection. Additional development is required to reduce sample fracturing and improve data quality at lowq.
Calibration and data collection protocols for reliable lattice parameter values in electron pair distribution function studies
Authors: Abeykoon A. M. Milinda , Hu Hefei , Wu Lijun , Zhu Yimei , Billinge Simon J. L.
Published: January 2015

Different protocols for calibrating electron pair distribution function (ePDF) measurements are explored and described for quantitative studies on nanomaterials. It is found that the most accurate approach to determine the camera length is to use a standard calibration sample of Au nanoparticles from the National Institute of Standards and Technology. Different protocols for data collection are also explored, as are possible operational errors, to find the best approaches for accurate data collection for quantitative ePDF studies.
A custom battery foroperandoneutron powder diffraction studies of electrode structure
Authors: Pang Wei Kong , Peterson Vanessa K.
Published: January 2015

Structure–property relations are central to understanding functional materials, and for battery research the use of neutron powder diffraction to reveal the atomistic and molecular-scale origin of battery performance characteristics is often essential. Althoughoperandoexperiments of this kind are increasingly common as neutron sources and instrumentation advance, these experiments are hindered by the often large barrier presented by the preparation of whole batteries that yield a neutron diffraction signal from the electrode of interest that is sufficient to extract detailed structural information. This article presents a custom battery that is specifically designed foroperandoneutron powder diffraction. The battery is a pouch type and contains layers of positive and negative electrodes in a parallel-connecting stack. Importantly, the battery can be easily prepared in most laboratories, is configurable, and can be used with both lithium and sodium charge carriers. This paper provides some exampleoperandoneutron powder diffraction studies using this battery.
Structural investigations of the α12Si–Ge superstructure
Authors: Etzelstorfer Tanja , Ahmadpor Monazam Mohammad Reza , Cecchi Stefano , Kriegner Dominik , Chrastina Daniel , Gatti Eleonora , Grilli Emanuele , Rosemann Nils , Chatterjee Sangam , Holý Vaclav , Pezzoli Fabio , Isella Giovanni , Stangl Julian
Published: January 2015

This article reports the X-ray diffraction-based structural characterization of the α12multilayer structure SiGe2Si2Ge2SiGe12[d'Avezac, Luo, Chanier & Zunger (2012).Phys. Rev. Lett.108, 027401], which is predicted to form a direct bandgap material. In particular, structural parameters of the superlattice such as thickness and composition as well as interface properties, are obtained. Moreover, it is found that Ge subsequently segregates into layers. These findings are used as input parameters for band structure calculations. It is shown that the direct bandgap properties depend very sensitively on deviations from the nominal structure, and only almost perfect structures can actually yield a direct bandgap. Photoluminescence emission possibly stemming from the superlattice structure is observed.
In situbending of an Au nanowire monitored by micro Laue diffraction
Authors: Leclere Cédric , Cornelius Thomas W. , Ren Zhe , Davydok Anton , Micha Jean-Sébastien , Robach Odile , Richter Gunther , Belliard Laurent , Thomas Olivier
Published: January 2015

This article reports on the first successful combination of micro Laue (µLaue) diffraction with an atomic force microscope forin situnanomechanical tests of individual nanostructures.In situthree-point bending on self-suspended gold nanowires was performed on the BM32 beamline at the ESRF using a specially designed atomic force microscope. During the bending process of the self-suspended wire, the evolution of µLaue diffraction patterns was monitored, allowing for extraction of the bending angle of the nanowire. This bending compares well with finite element analysis taking into account elastic constant bulk values and geometric nonlinearities. This novel experimental setup opens promising perspectives for studying mechanical properties at the nanoscale.
Radiation damage to nucleoprotein complexes in macromolecular crystallography
Authors: Bury Charles , Garman Elspeth F. , Ginn Helen Mary , Ravelli Raimond B. G. , Carmichael Ian , Kneale Geoff , McGeehan John E.
Published: January 2015

Significant progress has been made in macromolecular crystallography over recent years in both the understanding and mitigation of X-ray induced radiation damage when collecting diffraction data from crystalline proteins. In contrast, despite the large field that is productively engaged in the study of radiation chemistry of nucleic acids, particularly of DNA, there are currently very few X-ray crystallographic studies on radiation damage mechanisms in nucleic acids. Quantitative comparison of damage to protein and DNA crystals separately is challenging, but many of the issues are circumvented by studying pre-formed biological nucleoprotein complexes where direct comparison of each component can be made under the same controlled conditions. Here a model protein–DNA complex C.Esp1396I is employed to investigate specific damage mechanisms for protein and DNA in a biologically relevant complex over a large dose range (2.07–44.63 MGy). In order to allow a quantitative analysis of radiation damage sites from a complex series of macromolecular diffraction data, a computational method has been developed that is generally applicable to the field. Typical specific damage was observed for both the protein on particular amino acids and for the DNA on, for example, the cleavage of base-sugar N1—C and sugar-phosphate C—O bonds. Strikingly the DNA component was determined to be far more resistant to specific damage than the protein for the investigated dose range. At low doses the protein was observed to be susceptible to radiation damage while the DNA was far more resistant, damage only being observed at significantly higher doses.
In situsynchrotron X-ray diffraction investigation of the evolution of a PbO2/PbSO4surface layer on a copper electrowinning Pb anode in a novel electrochemical flow cell
Authors: Clancy Marie , Styles Mark J. , Bettles Colleen J. , Birbilis Nick , Chen Miao , Zhang Yansheng , Gu Qinfen , Kimpton Justin A. , Webster Nathan A. S.
Published: January 2015

This paper describes the quantitative measurement, byin situsynchrotron X-ray diffraction (S-XRD) and subsequent Rietveld-based quantitative phase analysis and thickness calculations, of the evolution of the PbO2and PbSO4surface layers formed on a pure lead anode under simulated copper electrowinning conditions in a 1.6 MH2SO4electrolyte at 318 K. This is the first report of a trulyin situS-XRD study of the surface layer evolution on a Pb substrate under cycles of galvanostatic and power interruption conditions, of key interest to the mining, solvent extraction and lead acid battery communities. The design of a novel reflection geometry electrochemical flow cell is also described. Thein situS-XRD results show that β-PbO2forms immediately on the anode under galvanostatic conditions, and undergoes continued growth until power interruption where it transforms to PbSO4. The kinetics of the β-PbO2to PbSO4conversion decrease as the number of cycles increases, whilst the amount of residual PbO2increases with the number of cycles due to incomplete conversion to PbSO4. Conversely, complete transformation of PbSO4to β-PbO2was observed in each cycle. The results of layer thickness calculations demonstrate a significant volume change upon PbSO4to β-PbO2transformation.
Twinning of aragonite – the crystallographic orbit and sectional layer group approach
Authors: Marzouki Mohamed-Amine , Souvignier Bernd , Nespolo Massimo
Published: January 2015

The occurrence frequency of the {110} twin in aragonite is explained by the existence of an important substructure (60% of the atoms) which crosses the composition surface with only minor perturbation (about 0.2 Å) and constitutes a common atomic network facilitating the formation of the twin. The existence of such a common substructure is shown by theC2/cpseudo-eigensymmetry of the crystallographic orbits, which contains restoration operations whose linear part coincides with the twin operation. Furthermore, the local analysis of the composition surface in the aragonite structure shows that the structure is built from slices which are fixed by the twin operation, confirming and reinforcing the crystallographic orbit analysis of the structural continuity across the composition surface.
Crystal structures offac-trichloridotris(trimethylphosphane-κP)rhodium(III) monohydrate andfac-trichloridotris(trimethylphosphane-κP)rhodium(III) methanol hemisolvate: rhodium structures that are isotypic with their iridium analogs
Authors: Merola Joseph S. , Franks Marion A.
Published: January 2015

The crystal structures of two solvates offac-trichloridotris(trimethylphosphane-κP)rhodium(III) are reported,i.e.one with water in the crystal lattice,fac-[RhCl3(Me3P)3]·H2O, and one with methanol in the crystal lattice,fac-[RhCl3(Me3P)3]·0.5CH3OH. These rhodium compounds exhibit distorted octahedral coordination spheres at the metal and are isotypic with the analogous iridium compounds previously reported by us [Merolaet al.(2013).Polyhedron,54, 67–73]. Comparison is made between the rhodium and iridium compounds, highlighting their isostructural relationships.
Crystal structure of paddle-wheel sandwich-type [Cu2{(CH3)2CO}{μ-Fe(η5-C5H4C[triple-bond]N)2}3](BF4)2·(CH3)2CO
Authors: Strehler Frank , Korb Marcus , Lang Heinrich
Published: January 2015

The molecular structure of (acetone-κO)tris(μ-ferrocene-1,1′-dicarbonitrile-κ2N:N′)dicopper(I) bis(tetrafluoridoborate) acetone monosolvate, [Cu2Fe3(C6H4N)6(C3H6O)](BF4)2·C3H6O, consists of two CuIions bridged by a ferrocene-1,1′-dicarbonitrile moiety in a paddle-wheel-architectured sandwich complex with two BF4−units as counter-ions. One of the latter is equally disordered over two sets of sites. The two CuIions are complexed in a trigonal–planar manner by three nitrileN-donor atoms. Further interactions by the O atom of an acetone molecule to one of the CuIatoms and a weak η2,π-interaction of two atoms of a cyclopentadienyl ring to the other CuIatom complete a distorted trigonal–pyramidal environment for each of the metal ions. A further acetone molecule is also present as a solvent molecule. The crystal packing is consolidated by several π–π interactions.
Multilingual metadata for cultural heritage materials
Authors: Matusiak Krystyna K. , Meng Ling , Barczyk Ewa , Shih Chia-Jung
Published: January 2015

Purpose

– The purpose of this paper is to explore multilingual access in digital libraries and to present a case study of creating bilingual metadata records for the Tse-Tsung Chow Collection of Chinese Scrolls and Fan Paintings. The project, undertaken at the University of Wisconsin-Milwaukee Libraries, provides access to digital copies of calligraphic and painted Chinese scrolls and fans from the collection donated by Prof Tse-Tsung Chow (Cezong Zhou).

Design/methodology/approach

– This paper examines the current approaches to multilingual indexing and retrieval in digital collections and presents a model of creating bilingual parallel records that combines translation with controlled vocabulary mapping.

Findings

– Creating multilingual metadata records for cultural heritage materials is in an early phase of development. Bilingual metadata created through human translation and controlled vocabulary mapping represents one of the approaches to multilingual access in digital libraries. Multilingual indexing of collections of international origin addresses the linguistic needs of the target audience, connects the digitized objects to their respective cultures and contributes to richer descriptive records. The approach that relies on human translation and research can be undertaken in small-scale digitization projects of rare cultural heritage materials. Language and subject expertise are required to create bilingual metadata records.

Research limitations/implications

– This paper presents the results of a case study. The approach to multilingual access that involves research, and it relies on human translation that can only be undertaken in small-scale projects.

Practical implications

– This case study of creating parallel records with a combination of translation and vocabulary mapping can be useful for designing similar bilingual digital collections.

Social implications

– This paper also discusses the obligations of holding institutions in undertaking digital conversion of the cultural heritage materials that originated in other countries, especially in regard to providing metadata records that reflect the language of the originating community.

Originality/value

– The research and practice in multilingual indexing of cultural heritage materials are very limited. There are no standardized models of how to approach building multilingual digital collections. This case study presents a model of providing bilingual access and enhancing the intellectual control of cultural heritage collections.
Changes in relationship conflict as a mediator of the longitudinal relationship between changes in role ambiguity and turnover intentions
Authors: Hill Kevin , Chênevert Denis , Poitras Jean
Published: January 2015

Purpose

– This study aims to clarify the relationship between changes in role ambiguity and turnover intentions. The authors propose that increases in role ambiguity over time can bias employees’ interpretations such that they come to view more relationship conflict at work. Because of the importance of social relationships at work, the authors propose that these increases in perceptions of relationship conflict mediate the positive effect of increases in role ambiguity on turnover intentions.

Design/methodology/approach

– This study is a two-wave longitudinal analysis of survey responses obtained from 146 employees working in the health-care sector over a three-year period. Structural equation modeling of cross-lagged correlations was used to test the hypothesized model.

Findings

– The positive relationship between increases in role ambiguity and turnover intentions over time is mediated by increases in relationship conflict. Results provide an integrative explanation of the phenomenon, uniting role theory, conflict theory and turnover theory.

Research limitations/implications

– Measures were all self-reported, and the non-experimental nature of the research design precludes causal interpretations. Future research should incorporate sources of measurement other than the focal employee and include additional variables presumed to operate in explaining these effects.

Practical implications

– Results highlight the need to monitor changes in employees’ role ambiguity beliefs over time. They also point to conflict management interventions as a potential means of reducing turnover intentions among employees who experience role ambiguity increases.

Originality/value

– The longitudinal examination of changes in these variables yields new insight into the nature of the relationships between role ambiguity, conflict and turnover intentions.
Evaluation of social enterprise outcomes and self-efficacy
Authors: Urban Boris
Published: January 2015

Purpose

– Understanding of social values is emerging, particularly as the phrases “social impact” and “social value” and the measurement thereof, are ubiquitous in both practitioner and academic discourse today. These terms are particularly relevant to those involved in social initiatives that are required at some stage to demonstrate to stakeholders, investors, funders, or simply themselves that they have the capability to deliver. The purpose of this paper is to link the evaluation of social enterprise outcomes to individual efficacy beliefs.

Design/methodology/approach

– The study is survey based (165 respondents) and conducted in two major cities in South Africa, where social entrepreneurship (SE) has unequivocal application. Social outcomes and self-efficacy are operationalized and measured along multi-dimensional scales. After checking the instruments for validity and reliability, correlational and multiple regression analyses are performed to determine the predicted relationship between the specified variables.

Findings

– Empirical findings reveal that evaluation of social enterprise outcomes is associated with higher levels of self-efficacy. Significant results support the propositions that perceptions of capability are positively related to implementing a social vision, sustainability, social networking, innovativeness and financial returns.

Research limitations/implications

– The main implications of this study are that measuring SE efficacy in advance of funding may indicate probability of venture success.

Originality/value

– The study is one of the first to provide a much needed account of the evaluation of social enterprises in relation to self-efficacy in an emerging market context.