bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of low transformation temperature welding (LTTW) consumables – distortion control and evolution of stresses
Authors: Thomas S. H. , Liu S.
Published: March 2014

Low transformation temperature welding (LTTW) consumables have been reported to reduce the tensile residual stresses in weldments. Martensitic transformation induces compressive residual stresses and improves the fatigue resistance of welded joints. Several of these LTTW consumables have been developed at the Colorado School of Mines. This research work presents the comparisons of the experimentally and Sysweld calculated measurements for distortions and residual stresses for different plate thicknesses. In addition, residual stress evolution with time graphs were plotted to determine the amount of martensite required to promote compressive residual stresses and to calculate the time required to induce compressive residual stresses. The main aspect of this research is to analyse the behaviour of LTTW consumables in terms of distortion and residual stresses on various plate thicknesses.
Synthesis and optical properties of composites based on ZnS nanoparticles embedded in layered magadiite
Authors: Chen Yufeng , Yu Gensheng
Published: March 2014

Composites based on ZnS nanparticles embedded in layered magadiite were synthesized via a three step process : protonation of Na-magadiite, ion exchange in order to introduce Zn(NH3)42+ in the interlayer space, and addition of Na2S to form ZnS particles in the interlayer space of magadiite. The composites obtained were characterized by X-ray power diffraction (XRD), Scanning Electron Microscopy coupled with Energy Dispersive Spectroscopy (SEM-EDS), Transmission Electron Microscopy (TEM), Raman spectroscopy, Photoluminscence spectra (PL), and UV-visible transmission spectra (UV-vis). Results indicated that ZnS nanoparticles embedded in magadiite presented different optical properties and photoluminescence enhancement properties compared with those of uncovered ZnS particles (without host magadiite).
Characterization and beneficiation studies for the removal of iron from a china clay from India
Authors: Kar B. , Sahoo H. , Rath S. S. , Rao D. S. , Das B.
Published: March 2014

A china clay sample from Jharkhand State, India, containing 65.0 wt.% SiO2, 22.7% Al2O3, 1.77% Fe2O3and 9.10% LOI was subjected to physical beneficiation and acid leaching studies to improve its quality. The clay was characterized by optical microscopy, XRD, and wet chemical analysis methods. Quartz and goethite are the two major impurities. High intensity magnetic separation removed only 10% of the total iron. Experiments with oxalic acid were carried out to establish the leaching kinetics of iron and the effects of acid concentration, time and temperature on iron leaching were also examined. The study demonstrated that ∼90% of total iron could be removed using 5% oxalic acid. The dissolution of iron from clay is best described by diffusion of ions through the product layer of constant size spherical particles. The activation energy of the leaching process over the temperature range was calculated to be 51.14 kJ/mol.
Determination of clay mineral aspect ratios from conductometric titrations
Authors: Weber C. , Heuser M. , Mertens G. , Stanjek H.
Published: March 2014

It has been established that disagreements between different methods of particle size determination of clay minerals can be ascribed to the non-spherical shape of the clay particles. However, by having aspect ratios available, particle sizes can be harmonized. One frequently used approach to obtain aspect ratios is to compare particle sizes originating from at least two devices operating on the basis of different physical principles. In this contribution aspect ratios of nine kaolinite-dominated and one dickite-dominated sample were determined by conductometric titrations. The aspect ratios obtained were then successfully used to correlate particle size distributions from dynamic laser scattering and acoustic spectroscopy.
Mineralogical and geotechnical characterization of clays from northern Morocco for their potential use in the ceramic industry
Authors: El Ouahabi M. , Daoudi L. , Fagel N.
Published: March 2014

This study focuses on the mineralogical and geotechnical characterization of northern Moroccan clays from the Tangier and Tetouan areas and compares them with the main clay deposits used in the Moroccan ceramic industry (from Meknes, Fes, Salé and Safi regions). Sampled clays were analysed by X-ray diffraction on bulk and clay (<2 μm) fractions to identify the mineralogical assemblages of the clay outcrops. Further analyses were conducted to determine the particle size distribution (laser diffraction particle analyser), the total organic matter content (Loss- On-Ignition measurements) and the Atterberg limits of the raw clays. The study aims at investigating the spatial variability of the clay samples and at evaluating their potential application as raw materials in the ceramic industry.

Tetouan and Tangier clays are characterized by diversified mineralogical assemblages (in particular a variable proportion of clay, quartz and calcite) compared with the Meknes, Fes, Salé and Safi clays (high clay content, quartz and calcite). The clay fraction of the Tetouan and Tangier samples is dominated by illite and kaolinite with variable amounts of chlorite, smectite and/or vermiculite. Illite is the dominant phase in the Meknes, Fes, Safi and Salé clays, but is associated with kaolinite. No direct relationship between the mineral assemblage composition and the lithology of the series was found.

The clays materials studied consist generally of fine particles with medium to high plasticity and low organic matter content. Due to their mineralogy, grain-size distribution and plasticity the clays appear to be suitable as raw material for the growing Morocco ceramic industry.
Natural radioactivity and trace element composition of natural clays used as cosmetic products in the Greek market
Authors: Papadopoulos A. , Giouri K. , Tzamos E. , Filippidis A. , Stoulos S.
Published: March 2014

Seven commercial cosmetic clays having different colour (white, green, pink and red) available in pharmacies and herbalists’ shops in the Greek market have been examined for their trace element concentrations (Ag, As, Ba, Be, Cd, Ce, Co, Cr, Cs, Cu, Ga, Hf, Hg, La, Mo, Ni, Pb, Rb, Sb, Sc, Se, Sr, Tl, V, Y, Zn and Zr). According to EC Regulation 1223/2009 the presence of As, Be, Cd, Cr, Hg, Ni, P, Pb, Sb, Se, Te, Tl, Zr and their compounds is prohibited in cosmetics. The most abundant trace elements in the white clays were P (330 μg/g), Pb (220 μg/g) and Zr (11 μg/g) and for the green clays were P (1250 μg/g), As (43 μg/g), Cr (31 μg/g), Pb (30 μg/g) and Ni (23 μg/g). Red and pink clays had lower concentrations of these elements than their white and green counterparts. The green clays are three times enriched in As and the kaolinite-rich white clays are nine times enriched in Pb compared to the Average Shale. The main mineral phase in the white clays is either kaolinite or calcite, in green clays smectite, in pink clay kaolinite and talc and in red clays it is vermiculite. The specific activities of 238U, 226Ra, 228Ra, 228Th and 40K were determined by γ-ray spectroscopy. The kaolinite-rich white clays are more enriched in 238U-series radionuclides (238U and 226Ra) than the smectitic green clays. In contrast, the green clays were more enriched in 232Th-series radionuclides (228Ra and 228Th) and 40K than the white clays.
Geochemistry of halloysite-7Å formation from plagioclase in trachyandesite rocks from Limnos Island, Greece
Authors: Papoulis D. , Komarneni S. , Panagiotaras D.
Published: March 2014

Trachyandesite rocks, occurring over an area of about 1 km2in the southwest part of Limnos Island, Greece, are altered mainly to halloysite. The samples were collected and analysed by polarizing microscopy, powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and chemical analysis. The alteration of plagioclase to halloysite follows seven discrete stages that are described in detail. The geochemical evaluation of the data shows enrichment of the lightREE(LREE) over heavyREE(HREE) as expressed by the (La/Yb)n ratio. TheΣLREErange from 206.44 to 272.30, while the sum ofHREEvaries from 11.01 to 26.26. The (La/Yb)n ratio ranges from 9.72 to 27.64. Fractionation amongLREEexpressed as (La/Sm)n and between middleREE(MREE) andHREEis shown as (Tb/Yb)n ratios. The most altered rocks close to the fault zone have high (Tb/Yb)n ratios and low (La/Sm)n and Eu/Eu* ratios. Although mineralogy and clay mineral textures indicate hydrothermal genesis of halloysite, the geochemical data are not conclusive due to a secondary weathering effect.
Characterization of two forms of sepiolite and related Mg-rich clay minerals from Yenidoğ an (Sivrihisar, Turkey)
Authors: Yeniyol M.
Published: March 2014

An Early Pliocene sedimentary succession in the Yenidoğan area, Sivrihisar, Turkey, consists of sepiolite, stevensite, kerolite, dolomite and magnesite. The geology, mineralogy and geochemistry of the succession was examined by extensive field work along several trenches and a representative measured section, followed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermal, and chemical analyses.

Structurally, two distinct forms of sepiolites were distinguished by XRD: (a) well crystallized sepiolite with a 110 reflection at 12.07–12.3 Å , and (b) poorly crystallized sepiolite in which the 110 reflection occurs at 12.7–13.0 Å (denoted as sepiolite-13Å ). Differences in crystal chemistry, thermal and morphological properties of these forms, the vibrational spectra and XRD characterization of the related phyllosilicates were also documented.

Stevensite, kerolite and sepiolite were formed by direct precipitation from alkaline lake water rich in Mg and Si. Sepiolite-13Å was probably formed by transformation from precursor smectite via dissolution-precipitation, more likely during early diagenesis. Environmental conditions such as ion concentration, salinity and variations in pH may have controlled the formation of the phyllosilicates.
Vysokýite, U4+[AsO2(OH)2]4·4H2O, a new mineral from Jáchymov, Czech Republic
Authors: Plášil J. , Hloušek J. , Škoda R. , Novák M. , Sejkora J. , Čejka J. , Veselovský F. , Majzlan J.
Published: March 2014

Vysokýite, U4+[(AsO2(OH)2]4(H2O)4(IMA 2012–067), was found growing on an altered surface of massive native As in the Geschieber vein, Jáchymov ore district, Western Bohemia, Czech Republic. The new mineral was found in association with běhounekite, štěpite, kaatialaite, arsenolite, claudetite and gypsum. It forms extremely fibrous light-green crystals up to 8 mm long. Crystals have an alabaster lustre and a greenish-white to greyish streak. Vysokýite is brittle with uneven fracture and perfect cleavage along (100) and (001); the Mohs hardness is ∼2. A density of 3.393 g/cm3was calculated using the empirical formula and unit-cell parameters obtained from a single-crystal diffraction experiment. Vysokýite is non-fluorescent under short or long wavelength UV radiation. It is colourless under the microscope, measured refractive indices are α' = 1.617(3), γ' = 1.654(3); the estimated optical orientation is α' ∼X, γ' ∼Z. The average of five spot wavelength dispersive spectroscopy (WDS) analyses is 29.44 UO2, 1.03 SiO2, 48.95 As2O5, 0.12 SO3, 15.88 H2O (calc.), total 95.42 wt.%. The empirical formula of vysokýite (based on 20 O a.p.f.u.) is U1.00[AsO2(OH)2]3.90(SiO4)0.16(SO4)0.01·4H2O. The As–O–H and O–H vibrations dominate in the Raman spectrum. Vysokýite is triclinic, space groupP, witha= 10.749(2),b= 5.044(3),c= 19.1778(7) Å, α = 89.872(15)°, β = 121.534(15)°, γ = 76.508(15)°, andV= 852.1(6) Å3,Z= 2 and Dcalc= 3.34 g·cm–3. The strongest diffraction peaks in the X-ray powder diffraction pattern are [dobsin Å(Irel.)(hkl)]: 8.872(100)(100), 8.067(50)(002), 6.399(7)(10), 4.773(6)(10), 3.411(10)(30), 3.197(18)(31). The crystal structure of vysokýite was solved from single-crystal X-ray diffraction data by the charge-flipping method and refined toR1= 0.0595 based on 2718 unique observed reflection, and towR2= 0.1160 for all 4173 unique reflections. The structure of vysokýite consists of UO8square antiprisms sharing all of their vertices with 8 As-tetrahedra to form infinite chains parallel to [010]. These chains are linked by hydrogen bonds involving terminal (OH) groups of the double-protonated As-tetrahedra and molecules of H2O located between the chains. The new mineral is named in honour of Arnošt Vysoký (1823–1872), the former chief of the Jáchymov mines and smelters, chemist and metallurgist.
Cannonite [Bi2O(SO4)(OH)2] from Alfenza (Crodo, Italy): crystal structure and morphology
Authors: Capitani G. C. , Catelani T. , Gentile P. , Lucotti A. , Zema M.
Published: March 2014

Canonite from Alfenza grows as crowded, radiating, acicular aggregates covering bismuthinite crystals. Individual crystals have a lozenge-shaped habit on {010}, the presumed cleavage plane of cannonite. Crystal structure refinements in the P21/c space group of two single crystals led to the following cell parameters: a = 7.7196(5) Å, b = 13.8856(9), c = 5.6980(4), b = 109.174(1)º (R1 = 0.0424); and a = 7.7100(8), b = 13.8717(14), c = 5.6939(6), b = 109.155(2)º (R1 = 0.0438). Hydrogen atoms were also localized in the density-difference Fourier map and refined with soft restraints on the bond distances. Raman and IR spectroscopy confirm the presence of OH groups and the absence of molecular water, and deliver OH···O geometry wholly comparable with the structure refinement. Electron microprobe analyses revealed no significant levels of elements other than those expected in the ideal formula except fluorine which was present up to 0.14 a.p.f.u. The crystal structure can be described in terms of anion-centred OBi4 edge-sharing tetrahedra forming chains running parallel to z and strongly cemented along x by isolated SO4 tetrahedra. Each OBi4 tetrahedron is further connected along y by OH groups, making walls of composition Bi4O2(SO4)2(OH)4 parallel to (010). These walls are tied to each other along y by fewer Bi–O–S bridges and weaker OH···O bonds.
Dervillite, Ag2AsS2, from Lengenbach quarry, Binn valley, Switzerland: occurrence and crystal structure
Authors: Bindi L. , Nestola F. , De Battisti L. , Guastoni A.
Published: March 2014

Dervillite, As2AsS2, has been found in a sample from the Lengenbach quarry in the Binn Valley, Valais, Switzerland. It occurs as very rare crystals up to 200 μm across on jordanite. Dervillite is opaque with a metallic lustre and shows a dark brown streak. The structure is monoclinic, space groupPc, witha= 9.6155(7),b= 12.9331(8),c= 6.8616(5) A ˚ ,b= 99.352(8)º,V= 842.0(1) Å3andZ= 8. In the crystal structure [R1= 0.060 for 2370 reflections withI> 2σ(I)], silver adopts various coordinations extending from quasi linear to quasi tetrahedral whereas arsenic forms very peculiar crystal-chemical environments, such as As(S2As) and As(S2AsAg). Such metalloid–metalloid or metal–metalloid bonds account for the apparent charge imbalance observed in the chemical formula.
Chiral edge-shared octahedral chains in liskeardite, [(Al,Fe)32(AsO4)18(OH)42(H2O)22]·52H2O, an open framework mineral with a pharmacoalumite-related structure
Authors: Grey I. E. , Mumme W. G. , Macrae C. M. , Caradoc-Davies T. , Price J. R. , Rumsey M. S. , Mills S. J.
Published: March 2014

The type specimen of liskeardite, (Al, Fe)3AsO4(OH)6·5H2O, from the Marke Valley Mine, Liskeard District, Cornwall, has been reinvestigated. The revised composition from electron microprobe analyses and structure refinement is [Al29.2Fe2.8(AsO4)18(OH)42(H2O)22]·52H2O. The crystal structure was determined using synchrotron data collected on a 2 μm diameter fibre at 100 K. Liskeardite has monoclinic symmetry, space group I2, with the unit-cell parameters a = 24.576(5), b = 7.754(2) Å, c = 24.641(5) Å, and β = 90.19(1)º. The structure was refined to R = 0.059 for 9769 reflections with I > 3σ(I). It is of an open framework type in which intersecting polyhedral slabs parallel to (101) and (10) form 17.4 Å × 17.4 Å channels along [010], with water molecules occupying the channels. Small amounts (<1 wt.%) of Na, K and Cu are probably adsorbed at the channel walls The framework comprises columns of pharmacoalumite-type, intergrown with chiral chains of six cis edge-shared octahedra. It can be described in terms of cubic close packing, with vacancies at both the anion and cation sites. The compositional and structural relationships between liskeardite and pharmacoalumite are discussed and a possible mechanism for liskeardite formation is presented.
Mineralogy of the P2-West ‘Kimberlite’, Wajrakarur kimberlite field, Andhra Pradesh, India: kimberlite or lamproite?
Authors: Kaur Gurmeet , Mitchell R. H.
Published: March 2014

A detailed mineralogical examination of representative material from the P2-West 'kimberlite' located in the Wajrakarur Kimberlite Field (India) demonstrates that significant differences exist between these rocks and archetypal hypabyssal kimberlite. The intrusion consists of an olivine-phyric facies which has been transected by, and includes clasts of, a consanguineous phlogopite-rich pegmatitic facies. The olivine-rich parts of P2-West are relatively fresh and consist of euhedral-to-subhedral microphenocrystal olivine set in a groundmass of fine-grained anhedral monticellite, amoeboid apatite, and subhedral-to-euhedral perovskite within a partially chloritized-to-fresh phlogopite-rich mesostasis. The rock lacks the abundant olivine macrocrysts characteristic of kimberlite. Monticellite crystals are commonly partially or completely replaced by pectolite and hydrogarnet. Similar material occurs as irregular aggregates randomly scattered throughout the groundmass. The groundmass, in contrast to that of hypabyssal kimberlites, is relatively poor in spinels. Atoll spinels are absent, with the majority of spinels occurring principally as mantles upon microphenocrystal olivine. Disaggregated cumulate-like assemblages of intergrown anhedral perovskite and spinel are common. Spinel compositions are unlike those of kimberlites and their evolutionary trend is similar to that of lamproite and lamprophyre spinels. The pegmatitic facies of the intrusion are highly and pervasively altered, and characterized by the presence of large clasts, veins, and irregular aggregates consisting of large (1–5 mm) crystals of pinkish-bronze Al-poor phlogopite intergrown with and/or including: apatite; pectolite-hydrogarnet pseudomorphs after an unidentified euhedral phase; chlorite laths; barytolamprophyllite; perovskite; tausonite; diverse Sr-Ba-carbonates; and baryte. The presence of barytolamprophyllite and tausonite are typical of potassic undersaturated alkaline rocks and have never been reported from kimberlite; however, neither feldspar nor feldspathoids are present in P2-West. Micas in fresh and altered rocks are Al2O3- and BaO-poor, and exhibit compositional evolutionary trends towards tetraferriphlogopite rather than kinoshitalite. On the basis of these mineralogical data it is suggested that P2-West represents an unusual lamproite-like intrusion which has undergone extensive hydrothermal deuteric alteration and should not be considered a bona fide kimberlite.
A single-crystal neutron and X-ray diffraction study of a Li, Be-bearing brittle mica
Authors: Gatta G. D. , Nénert G. , Guastella G. , Lotti P. , Guastoni A. , Rizzato S.
Published: March 2014

The crystal chemistry of a meso-octahedral Li,Be-bearing mica from the Harding pegmatite (Dixon, Taos County, New Mexico, USA) has been investigated by constant-wavelength single-crystal neutron diffraction at 20 K, single-crystal X-ray diffraction at 100 K and inductively coupled plasma-atomic emission spectrometry (ICP-AES). The chemical composition based on ICP-AES analysis leads to the following chemical formula (calculated on the basis of 12 oxygen atoms):Ca(Na0.26K0.04Ca0.69)∑0.99M(Li0.29Mg0.03Fe0.023+Al1.78)∑2.12T(Al1.73Be0.16Si2.11)S4.00O12H2.53. The apparent excess of H is probably due to the fact that the fraction of H2O was assumed by difference to 100 wt.%, and slightly overestimated. On the basis of the previous experimental findings on Li,Be-bearing mica, X-ray (at 100 K) and neutron (at 20 K) structure refinements were performed in the space groupsCcandC2/c. The neutron structure refinement in the space groupCcoffers a view about the (Al,Be,Si)-tetrahedral ordering: the best fit of the refinement was reached with theT1 andT4 sites occupied by (Be + Al) andT2 andT3 fully occupied by Si. This leads to a final population ofT(Al1.88Be0.12Si2.00)∑4.00p.f.u., in reasonable agreement with the chemical analysis. The neutron refinement provides unambigous evidence of the occurrence of Li at theM1 site. The refined fraction of Li at theM1 site ranges between 0.27 and 0.29 a.p.f.u., in excellent agreement with the chemical analysis. The presence of Li, at least at a significant level, at theM2 (andM3) site can be ruled out, as a full site occupancy with the scattering length of Al was obtained. The location of the H sites and the complex hydrogen-bonding scheme are described. A comparison between the structure features of this Li,Be-mica and other brittle micas is carried out.
openBEB: open biological experiment browser for correlative measurements
Authors: Ramakrishnan Chandrasekhar , Bieri Andrej , Sauter Nora , Roizard Sophie , Ringler Philippe , Müller Shirley A , Goldie Kenneth N , Enimanev Kaloyan , Stahlberg Henning , Rinn Bernd , Braun Thomas
Published: March 2014

Background

New experimental methods must be developed to study interaction networks in systems biology. To reduce biological noise, individual subjects, such as single cells, should be analyzed using high throughput approaches. The measurement of several correlative physical properties would further improve data consistency. Accordingly, a considerable quantity of data must be acquired, correlated, catalogued and stored in a database for subsequent analysis.

Results

We have developed openBEB (open Biological Experiment Browser), a software framework for data acquisition, coordination, annotation and synchronization with database solutions such as openBIS. OpenBEB consists of two main parts: A core program and a plug-in manager. Whereas the data-type independent core of openBEB maintains a local container of raw-data and metadata and provides annotation and data management tools, all data-specific tasks are performed by plug-ins. The open architecture of openBEB enables the fast integration of plug-ins, e.g., for data acquisition or visualization. A macro-interpreter allows the automation and coordination of the different modules. An update and deployment mechanism keeps the core program, the plug-ins and the metadata definition files in sync with a central repository.

Conclusions

The versatility, the simple deployment and update mechanism, and the scalability in terms of module integration offered by openBEB make this software interesting for a large scientific community. OpenBEB targets three types of researcher, ideally working closely together: (i) Engineers and scientists developing new methods and instruments, e.g., for systems-biology, (ii) scientists performing biological experiments, (iii) theoreticians and mathematicians analyzing data. The design of openBEB enables the rapid development of plug-ins, which will inherently benefit from the “house keeping” abilities of the core program. We report the use of openBEB to combine live cell microscopy, microfluidic control and visual proteomics. In this example, measurements from diverse complementary techniques are combined and correlated.
Oral cancer cells may rewire alternative metabolic pathways to survive from siRNA silencing of metabolic enzymes
Authors: Zhang Min , Chai Yang D , Brumbaugh Jeffrey , Liu Xiaojun , Rabii Ramin , Feng Sizhe , Misuno Kaori , Messadi Diana , Hu Shen
Published: March 2014

Background

Cancer cells may undergo metabolic adaptations that support their growth as well as drug resistance properties. The purpose of this study is to test if oral cancer cells can overcome the metabolic defects introduced by using small interfering RNA (siRNA) to knock down their expression of important metabolic enzymes.

Methods

UM1 and UM2 oral cancer cells were transfected with siRNA to transketolase (TKT) or siRNA to adenylate kinase (AK2), and Western blotting was used to confirm the knockdown. Cellular uptake of glucose and glutamine and production of lactate were compared between the cancer cells with either TKT or AK2 knockdown and those transfected with control siRNA. Statistical analysis was performed with student T-test.

Results

Despite the defect in the pentose phosphate pathway caused by siRNA knockdown of TKT, the survived UM1 or UM2 cells utilized more glucose and glutamine and secreted a significantly higher amount of lactate than the cells transferred with control siRNA. We also demonstrated that siRNA knockdown of AK2 constrained the proliferation of UM1 and UM2 cells but similarly led to an increased uptake of glucose/glutamine and production of lactate by the UM1 or UM2 cells survived from siRNA silencing of AK2.

Conclusions

Our results indicate that the metabolic defects introduced by siRNA silencing of metabolic enzymes TKT or AK2 may be compensated by alternative feedback metabolic mechanisms, suggesting that cancer cells may overcome single defective pathways through secondary metabolic network adaptations. The highly robust nature of oral cancer cell metabolism implies that a systematic medical approach targeting multiple metabolic pathways may be needed to accomplish the continued improvement of cancer treatment.
Time-frequency optimization for discrimination between imagination of right and left hand movements based on two bipolar electroencephalography channels
Authors: Yang Yuan , Chevallier Sylvain , Wiart Joe , Bloch Isabelle
Published: March 2014

To enforce a widespread use of efficient and easy to use brain-computer interfaces (BCIs), the inter-subject robustness should be increased and the number of electrodes should be reduced. These two key issues are addressed in this contribution, proposing a novel method to identify subject-specific time-frequency characteristics with a minimal number of electrodes. In this method, two alternative criteria, time-frequency discrimination factor (TFDF) andFscore, are proposed to evaluate the discriminative power of time-frequency regions. Distinct from classical measures (e.g., Fisher criterion,r2coefficient), the TFDF is based on the neurophysiologic phenomena, on which the motor imagery BCI paradigm relies, rather than only from statistics.Fscore is based on the popularFisher’sdiscriminant and purely data driven; however, it differs from traditional measures since it provides a simple and effective measure for quantifying the discriminative power of a multi-dimensional feature vector. The proposed method is tested on BCI competition IV datasets IIa and IIb for discriminating right and left hand motor imagery. Compared to state-of-the-art methods, our method based on both criteria led to comparable or even better classification results, while using fewer electrodes (i.e., only two bipolar channels, C3 and C4). This work indicates that time-frequency optimization can not only improve the classification performance but also contribute to reducing the number of electrodes required in motor imagery BCIs.
Animal models of chronic tympanic membrane perforation: in response to plasminogen initiates and potentiates the healing of acute and chronic tympanic membrane perforations in mice
Authors: Wang Allen Y , Shen Yi , Wang Jeffrey T , Eikelboom Robert H , Dilley Rodney J
Published: March 2014

Tympanic membrane perforations (TMP) are relatively common but are typically not treated in their acute stage, as most will heal spontaneously in 7–10 days. Those cases which fail to heal within 3 months are called chronic TMP which attract surgical intervention (e.g. myringoplasty), typically with a temporalis fascia autograft. New materials for the repair of chronic TMP are being developed to address deficiencies in the performance of autografts by undergoing evaluation in animal models prior to clinical study. However, there is currently a lack of ideal chronic TMP animal models available, hindering the development of new treatments. Various techniques and animal species have been investigated for the creation of chronic TMP with varied success. In the present commentary, we bring to the attention of readers the recent report by Shen et al. in Journal of Translational Medicine. The study reported the creation of a chronic TMP animal model in plasminogen gene deficient mice. However, the short observation time (9, 19 days), lack of success rate and the scarcity of solid evidence (e.g. otoscopic & histologic images) to confirm the chronicity of TMP warrant a more thorough discussion.
A data repository and analysis framework for spontaneous neural activity recordings in developing retina
Authors: Eglen Stephen John , Weeks Michael , Jessop Mark , Simonotto Jennifer , Jackson Tom , Sernagor Evelyne
Published: March 2014

Background:

During early development, neural circuits fire spontaneously, generating activity episodes with complex spatiotemporal patterns. Recordings of spontaneous activity have been made in many parts of the nervous system over the last 25 years, reporting developmental changes in activity patterns and the effects of various genetic perturbations.

Results:

We present a curated repository of multielectrode array recordings of spontaneous activity in developing mouse and ferret retina. The data have been annotated with minimal metadata and converted into HDF5. This paper describes the structure of the data, along with examples of reproducible research using these data files. We also demonstrate how these data can be analysed in the CARMEN workflow system. This article is written as a literate programming document; all programs and data described here are freely available.

Conclusions:

1. We hope this repository will lead to novel analysis of spontaneous activity recorded in different laboratories. 2. We encourage published data to be added to the repository. 3. This repository serves as an example of how multielectrode array recordings can be stored for long-term reuse.
Prevalence, predictors and outcome of hypofibrinogenaemia in trauma: a multicentre observational study
Authors: Hagemo Jostein S , Stanworth Simon , Juffermans Nicole P , Brohi Karim , Cohen Mitchell Jay , Johansson Pär I , Røislien Jo , Eken Torsten , Næss Paal A , Gaarder Christine
Published: March 2014

Introduction

Exsanguination due to trauma-induced coagulopathy is a continuing challenge in emergency trauma care. Fibrinogen is a crucial factor for haemostatic competence, and may be the factor that reaches critically low levels first. Early fibrinogen substitution is advocated by a number of authors. Little evidence exists regarding the indications for fibrinogen supplementation in the acute phase. This study aims to estimate the prevalence of hypofibrinogenaemia in a multi-center trauma population, and to explore how initial fibrinogen concentration relates to outcome. Also, factors contributing to low fibrinogen levels are identified.

Methods

Patients arriving in hospital less than 180 minutes post-injury requiring full trauma team activation in four different centers were included in the study. Time from injury, patient demographics, injury severity scores (ISS) and 28 days outcome status were recorded. Initial blood samples for coagulation and blood gas were analyzed. Generalized additive regression, piecewise linear regression, and multiple linear regression models were used for data analyses.

Results

Out of 1,133 patients we identified a fibrinogen concentration ≤1.5g/L in 8.2%, and <2 g/L in 19.2%. A non-linear relationship between fibrinogen concentration and mortality was detected in the generalized additive and piecewise linear regression models. In the piecewise linear regression model we identified a breakpoint for optimal fibrinogen concentration at 2.29 g/L (95% confidence interval (CI): 1.93 to 2.64). Below this value the odds of death by 28 days was reduced by a factor of 0.08 (95% CI: 0.03 to 0.20) for every unit increase in fibrinogen concentration. Low age, male gender, lengthened time from injury, low base excess and high ISS were unique contributors to low fibrinogen concentrations on arrival.

Conclusions

Hypofibrinogenaemia is common in trauma and strongly associated with poor outcome. Below an estimated critical fibrinogen concentration value of 2.29 g/L a dramatic increase in mortality was detected. This finding indicates that the negative impact of low fibrinogen concentrations may have been previously underestimated. A number of clinically identifiable factors are associated with hypofibrinogenaemia. They should be considered in the management of massively bleeding patients. Interventional trials with fibrinogen substitution in high-risk patients need to be undertaken.
Decreased cardiac excitability secondary to reduction of sodium current may be a significant contributor to reduced contractility in a rat model of sepsis
Authors: Koesters Andrew , Engisch Kathrin L , Rich Mark M
Published: March 2014

Introduction

Multisystem organ failure remains a poorly understood complication of sepsis. During sepsis, reduced excitability contributes to organ failure of skeletal muscle, nerves and the spinal cord. The goal of this study was to determine whether reduced excitability might also contribute to cardiac failure during sepsis.

Methods

Wistar rats were made septic by cecal ligation and puncture. One day later, action potentials were recorded from beating left ventricular papillary muscle ex vivo by impaling myocytes with sharp microelectrodes.

Results

In cardiac papillary muscle from septic rats, action potential amplitude and rate of rise were reduced, while threshold was elevated. These changes in action potential properties suggest sepsis selectively reduces sodium current. To determine the effects of selective reduction in sodium current, we applied tetrodotoxin to papillary muscle from healthy rats and found reduction in action potential amplitude and rate of rise, as well as elevation of threshold. The changes were similar to those triggered by sepsis. Blocking calcium current using nifedipine did not mimic action potential changes induced by sepsis. Contractility of healthy papillary muscle was reduced to 40% of normal following partial block of sodium current by tetrodotoxin, close to the low contractility of septic papillary muscle, which was 30% of normal.

Conclusions

Our data suggest cardiac excitability is reduced during sepsis in rats. The reduction in excitability appears to be primarily due to reduction of sodium current. The reduction in sodium current may be sufficient to explain most of the reduction in cardiac contractility during sepsis.
Fault identification using dip-guided facet model edge detector
Authors: Song Jianguo , Mu Xing , Li Zhe , Wang Changjiang , Sun Yongzhuang , Imran Muhammad
Published: March 2014

To characterize reservoirs with complex fault blocks or lithology, geophysicists often need to depict the edge of geologic bodies such as small faults. Edge detection is a powerful tool for structural feature identification; however, conventional edge-detection operators that are widely used in image edge detection are not always adequate for seismic data. In fact, most conventional edge-detection methods are effective along a plane. For seismic data, it is more appropriate to detect edge information along the slope of an event. We evaluated a new method for fault detection based on a surface-fitting algorithm. The surface-fitting algorithm was used to find the local slope of a seismic event, and then edge detection is performed along this local fitted plane. For each point in a seismic volume, we defined a small neighborhood in a plane parallel to the local reflector with the help of dip estimation. The data in the neighborhood were then approximated by a bivariate cubic function, called the facet model. Then, the local gradient of the function is calculated and referred to as the facet model attribute. To enhance the robustness of the output attribute and suppress noise, the gradient values were summed over a vertical window and normalized by the energy. To evaluate the performance of our method, we also calculated the dip-guided Sobel attribute and variance attribute. Compared with these three attributes, the result of our method suggested more accurate edge detection, and it showed more detail in fault detection.
Circulating Vitamin D, Supplement Use, and Cardiovascular Disease Risk: The MrOS Sleep Study
Authors: Bajaj Archna , Stone Katie L. , Peters Katherine , Parimi Neeta , Barrett-Connor Elizabeth , Bauer Doug , Cawthon Peggy M. , Ensrud Kristine E. , Hoffman Andrew R. , Orwoll Eric , Schernhammer Eva S.
Published: March 2014

Context:

Evidence suggests an inverse association between circulating 25(OH) vitamin D and cardiovascular disease (CVD).

Objective:

To determine the association between serum 25(OH) vitamin D and risk for CVD events.

Setting and Design:

From March 2000 to April 2002, participants were recruited for the Osteoporotic Fractures in Men (MrOS) study. Between December 2003 and March 2005, members of the MrOS cohort were invited to participate in the MrOS Sleep Study. Participants were recruited from 6 clinical centers across the United States and followed for a mean of 5.9 years. Three-thousand-one-hundred-thirty-five men ages 65 and older were included from the MrOS cohort, of whom 116 were excluded for missing vitamin D or CVD data. Participants were divided into two groups based on serum 25(OH) vitamin D levels, <20 ng/mL and ≥20 ng/mL. Participants were followed for CVD endpoints including coronary heart disease (CHD) and cerebrovascular events. Age- and multivariable-adjusted hazard ratios were calculated and stratified by use of vitamin D containing supplements.

Results:

We observed no significant association between circulating 25(OH) vitamin D and risk of CVD event (HR, 0.91; 95% confidence interval (CI), 0.73–1.13) and CHD event (HR, 0.81; 95% CI, 0.61–1.07). For cerebrovascular events, men with vitamin D deficiency exhibited a higher risk (HR, 1.44; 95% CI, 1.00–2.08) using the minimally adjusted model and after excluding supplement users (HR, 1.70; 95% CI, 1.02–2.83).

Conclusions:

25(OH) vitamin D was not associated with risk of CVD and CHD events. However, vitamin D deficiency may be associated with an increased risk of cerebrovascular events.
Type I TARPs promote dendritic growth of early postnatal neocortical pyramidal cells in organotypic cultures
Authors: Hamad Mohammad I. K. , Jack Alexander , Klatt Oliver , Lorkowski Markus , Strasdeit Tobias , Kott Sabine , Sager Charlotte , Hollmann Michael , Wahle Petra
Published: March 2014

The ionotropic α-amino-3-hydroxy-5-methyl-4-isoxazole propionate glutamate receptors (AMPARs) have been implicated in the establishment of dendritic architecture. The transmembrane AMPA receptor regulatory proteins (TARPs) regulate AMPAR function and trafficking into synaptic membranes. In the current study, we employ type I and type II TARPs to modulate expression levels and function of endogenous AMPARs and investigate in organotypic cultures (OTCs) of rat occipital cortex whether this influences neuronal differentiation. Our results show that in early development [5-10 days in vitro (DIV)] only the type I TARP γ-8 promotes pyramidal cell dendritic growth by increasing spontaneous calcium amplitude and GluA2/3 expression in soma and dendrites. Later in development (10-15 DIV), the type I TARPs γ-2, γ-3 and γ-8 promote dendritic growth, whereas γ-4 reduced dendritic growth. The type II TARPs failed to alter dendritic morphology. The TARP-induced dendritic growth was restricted to the apical dendrites of pyramidal cells and it did not affect interneurons. Moreover, we studied the effects of short hairpin RNA-induced knockdown of endogenous γ-8 and showed a reduction of dendritic complexity and amplitudes of spontaneous calcium transients. In addition, the cytoplasmic tail (CT) of γ-8 was required for dendritic growth. Single-cell calcium imaging showed that the γ-8 CT domain increases amplitude but not frequency of calcium transients, suggesting a regulatory mechanism involving the γ-8 CT domain in the postsynaptic compartment. Indeed, the effect of γ-8 overexpression was reversed by APV, indicating a contribution of NMDA receptors. Our results suggest that selected type I TARPs influence activity-dependent dendritogenesis of immature pyramidal neurons.
Drinking problems on a ‘simple’ diet: physiological convergence in nectar-feeding birds
Authors: Nicolson Susan W. , Fleming Patricia A.
Published: March 2014

Regulation of energy and water are by necessity closely linked in avian nectarivores, because the easily available sugars in nectar are accompanied by an excess of water but few electrolytes. In general, there is convergence in morphology and physiology between three main lineages of avian nectarivores that have evolved on different continents – the hummingbirds, sunbirds and honeyeaters. These birds show similar dependence of sugar preferences on nectar concentration, high intestinal sucrase activity and rapid absorption of hexoses via mediated and paracellular routes. There are differences, however, in how these lineages deal with energy challenges, as well as processing the large volumes of preformed water ingested in nectar. While hummingbirds rely on varying renal water reabsorption, the passerine nectarivores modulate intestinal water absorption during water loading, thus reducing the impact on the kidneys. Hummingbirds do not generally cope with salt loading, and have renal morphology consistent with their ability to produce copious dilute urine; by contrast, as well as being able to deal with dilute diets, honeyeaters and sunbirds are more than capable of dealing with moderately high levels of added electrolytes. And finally, in response to energy challenge, hummingbirds readily resort to torpor, while the passerines show renal and digestive responses that allow them to deal with short-term fasts and rapidly restore energy balance without using torpor. In conclusion, sunbirds and honeyeaters demonstrate a degree of physiological plasticity in dealing with digestive and renal challenges of their nectar diet, while hummingbirds appear to be more constrained by this diet.
Biomechanical determinants of bite force dimorphism inCyclommatus metalliferstag beetles
Authors: Goyens Jana , Dirckx Joris , Dierick Manuel , Van Hoorebeke Luc , Aerts Peter
Published: March 2014

In the stag beetle family (Lucanidae), males have diverged from females by sexual selection. The males fight each other for mating opportunities with their enlarged mandibles. It is known that owners of larger fighting apparatuses are favoured to win the male–male fights, but it was unclear whether male stag beetles also need to produce high bite forces while grabbing and lifting opponents in fights. We show that male Cyclommatus metallifer stag beetles bite three times as forcefully as females. This is not entirely unexpected given the spectacular nature of the fights, but all the more impressive given the difficulty of achieving this with their long mandibles (long levers). Our results suggest no increase in male intrinsic muscle strength to accomplish this. However, morphological analyses show that the long mandibular output levers in males are compensated by elongated input levers (and thus a wider anterior side of the head). The surplus of male bite force capability is realized by enlargement of the closer muscles of the mandibles, while overall muscle force direction remained optimal. To enable the forceful bites required to ensure male reproductive success, male head size and shape are adapted for long input levers and large muscles. Therefore, the entire head should be regarded as an integral part of male armature.
Common effect of the mucus transferred during mating in two dart-shooting snail species from different families
Authors: Kimura Kazuki , Chiba Satoshi , Koene Joris M.
Published: March 2014

Several taxa of pulmonate land snails exhibit a conspicuous mating behaviour, the shooting of so-called love darts. During mating, such land snail species stab a mating partner with a mucus-coated dart. It has previously been shown that the sperm donor physiologically influences the sperm recipient via the mucus covering the dart and thereby decreases the number of sperm digested by the recipient. However, the generality of this effect of the dart's mucus is unclear, because almost all the previous studies on the effect of the mucus used the brown garden snail Cornu aspersum from the family Helicidae. Therefore, the relationship between the acquisition of the mucus effect on the recipient and the evolution of the dart itself, and its mucus, is still open to debate. To test the commonality of the physiological effect of the dart mucus, we examined this in Euhadra peliomphala, a species from the Bradybaenidae family, and compared our findings with the results of previous work using C. aspersum. Our experiments showed that in E. peliomphala, the dart mucus had a physiological effect and lowered the accessibility of the gametolytic organ, as found in C. aspersum. This indicates that in various dart-bearing species the mucus from the dart glands targets the same organ and that the inhibition of sperm digestion has played a crucial role in the evolution of the dart and its mucus.
Compensation and Peer Effects in Competing Sales Teams
Authors: Chan Tat Y. , Li Jia , Pierce Lamar
Published: March 2014

This paper examines how compensation systems impact peer effects and competition in collocated sales teams. We use department store sales data to show that compensation systems influence worker incentives to help and compete with peers within the same firm, which in turn changes the capability of the firm to compete with rivals. Compensation also affects how salespeople impact peers at collocated competing firms, thereby impacting market competition. Moreover, compensation influences how salespeople strategically discount prices in response to peers. Our results suggest that heterogeneity in worker ability enhances firm performance under team-based compensation while hurting individual-based firms and that peer interactions are critical considerations in designing sales force incentive plans and broader firm strategy.

This paper was accepted by Bruno Cassiman, business strategy.
Differences in Trading and Pricing Between Stock and Index Options
Authors: Lemmon Michael , Ni Sophie Xiaoyan
Published: March 2014

We find that the demand for stock options that increases exposure to the underlying is positively related to the individual investor sentiments and past market returns, whereas the demand for index options is invariant to these factors. These differences in trading patterns are also reflected in the differences in the composition of traders with different types of options—options on stocks are actively traded by individual investors, whereas trades in index options are more often motivated by the hedging demand of sophisticated investors. Consistent with a demand-based view of option pricing, the individual investor sentiments and past market returns are related to time-series variations in the slope of the implied volatility smile of stock options, but they have little impact on the prices of index options. The pricing impact is more pronounced in options with a higher concentration of unsophisticated investors and those with higher delta hedging costs. Our results provide evidence that factors not related to fundamentals also impact security prices.

This paper was accepted by Brad Barber, finance.