bluuebunny/crossref_metadata_2025 huggingface dataset:
Defect detection inside superconducting 1.3 GHz cavities by means of x-ray fluorescence spectroscopy
Authors: Bertucci M. , Michelato P. , Moretti M. , Navitski A. , Pagani C.
Published: January 2016

X-ray fluorescence probe for detection of foreign material inclusions on the inner surface of superconducting cavities has been developed and tested. The setup detects trace element content such as a few micrograms of impurities responsible for thermal breakdown phenomena limiting the cavity performance. The setup has been customized for the geometry of 1.3 GHz TESLA-type niobium cavities and focuses on the surface of equator area at around 103 mm from the centre axis of the cavities with around 20 mm detection spot. More precise localization of inclusions can be reconstructed by means of angular or lateral displacement of the cavity. Preliminary tests confirmed a very low detection limit for elements laying in the high efficiency spectrum zone (from 5 to 10 keV), and a high angular resolution allowing an accurate localization of defects within the equator surface.
Pattern formation in thin films of polymer solutions: Theory and simulations
Authors: Sarika C. K. , Tomar Gaurav , Basu J. K.
Published: January 2016

Self-assembly has been recognized as an efficient tool for generating a wide range of functional, chemically, or physically textured surfaces for applications in small scale devices. In this work, we investigate the stability of thin films of polymer solutions. For low concentrations of polymer in the solution, long length scale dewetting patterns are obtained with wavelength approximately few microns. Whereas, for concentrations above a critical value, bimodal dispersion curves are obtained with the dominant wavelength being up to two orders smaller than the usual dewetting length scale. We further show that the short wavelength corresponds to the phase separation in the film resulting in uniformly distributed high and low concentration regions. Interestingly, due to the solvent entropy, at very high concentration values of polymer, a re-entrant behaviour is observed with the dominant length scale now again corresponding to the dewetting wavelength. Thus, we show that the binary films of polymer solutions provide additional control parameters that can be utilized for generating functional textured surfaces for various applications.
In situ multi-modal monitoring of solvent vapor swelling in polymer thin films
Authors: Hoang Dat Tien , Yang Jaesung , Paeng Keewook , Kwon Youngah , Kweon Oh Sang , Kaufman Laura J.
Published: January 2016

Polymer processing techniques involving solvent vapor swelling are typically challenging to control and thus reproduce. Moreover, traditional descriptions of solvent swollen films lack microscopic detail. We describe the design and use of an apparatus that facilitates macroscopic and microscopic characterization of samples undergoing solvent vapor swelling in a controlled environment. The experimental design incorporates three critical characteristics: (1) a mass-flow controlled solvent vapor delivery system allows for precise control of the amount of solvent vapor delivered to the sample, (2) a sample prepared on a quartz crystal microbalance allows for real-time assessment of the extent of sample swelling, (3) a second sample prepared and assessed in parallel on a coverslip allows real-time fluorescence microscopy during swelling. We demonstrate that this apparatus allows for single-particle tracking, which in turn facilitates in situ monitoring of local environments within the solvent-swollen film.
Sub-terahertz microsecond optically controlled switch with GaAs active element beyond the photoelectric threshold
Authors: Kulygin M. , Denisov G. , Vlasova K. , Andreev N. , Shubin S. , Salahetdinov S.
Published: January 2016

We study an unusual working regime of a recently developed sub-terahertz microwave cavity-based switch. The resonator cavity includes a semiconductor plate which is illuminated by laser emission beyond the photoelectric threshold. Despite a significant change to the conventional process of photoelectric effect we have found that the switch works. Typical switching performance rate is about 1 μs for the regime. A process of carrier density relaxation beyond the photoelectric threshold is discussed. An idea of diagnostic method for the semiconductor’s quality is proposed.
Coupling of caged molecule dynamics to Johari-Goldstein β-relaxation in metallic glasses
Authors: Wang Z. , Ngai K. L. , Wang W. H. , Capaccioli S.
Published: January 2016

Three recently published papers have discovered a general property of the fast caged dynamics observed in the glassy states of polyalcohols (S. Capaccioli et al., J. Phys. Chem. B 119, 8800 (2015)), amorphous polymers (K. L. Ngai et al., J. Phys. Chem. B 119, 12502 (2015)), and van der Waals molecular glass-formers (K. L. Ngai et al., J. Phys. Chem. B 119, 12519 (2015)). The fast caged dynamics are manifested as nearly constant loss (NCL) in dielectric and mechanical susceptibility. Shown before in these papers is the intensity of the caged dynamics change temperature dependence at a temperature THF nearly coincident with the secondary glass transition temperature Tgβ, at which the Johari-Goldstein (JG) β-relaxation time τJG reaches ∼103 s. Evidently this finding indicates the coupling of the caged dynamics to the secondary glass transition. The glass-formers considered so far are all soft matters. However, the generality of the phenomenon and its explanation implies that the relation, THF ≈ Tgβ, should be observed in other classes of glass-formers. In this paper, we extend the consideration of the phenomenon and explanation to metallic glasses, which are not soft matter. The experimental data presented show the same phenomenon, supporting its generality and fundamental importance in the physics of glass and glass transition.
A global stability approach to wake and path instabilities of nearly oblate spheroidal rising bubbles
Authors: Cano-Lozano José Carlos , Tchoufag Joël , Magnaudet Jacques , Martínez-Bazán Carlos
Published: January 2016

A global Linear Stability Analysis (LSA) of the three-dimensional flow past a nearly oblate spheroidal gas bubble rising in still liquid is carried out, considering the actual bubble shape and terminal velocity obtained for various sets of Galilei (Ga) and Bond (Bo) numbers in axisymmetric numerical simulations. Hence, this study extends the stability analysis approach of Tchoufag et al. [“Linear stability and sensitivity of the flow past a fixed oblate spheroidal bubble,” Phys. Fluids 25, 054108 (2013) and “Linear instability of the path of a freely rising spheroidal bubble,” J. Fluid Mech. 751, R4 (2014)] (which considered perfectly spheroidal bubbles with an arbitrary aspect ratio) to the case of bubbles with a realistic fore-aft asymmetric shape (i.e., a flatter front and a more rounded rear). The critical curve separating stable and unstable regimes for the straight vertical path is obtained both in the (Ga,Bo) and the (Re,χ) planes, where Re is the bubble Reynolds number and χ its aspect ratio (i.e., the major-to-minor axes length ratio). This provides new insight into the effect of the shape asymmetry on the wake instability of bubbles held fixed in a uniform stream and on the path instability of freely rising bubbles, respectively. For the range of Ga and Bo explored here, we find that the flow past a bubble with a realistic shape is generally more stable than that past a perfectly spheroidal bubble with the same aspect ratio. This study also provides the first critical curve for the onset of path instability that can be compared with experimental observations. The tendencies revealed by this critical curve agree well with those displayed by available data. The quantitative agreement is excellent for O(1) Bond numbers. However, owing to two simplifying assumptions used in the LSA scheme, namely, the steadiness of the base state and the uncoupling between the bubble shape and the flow disturbances, quantitative discrepancies (up to 20%–30%) with experimental threshold values of the Galilei number remain for both small and large Bond numbers.
Flexible polyelectrolyte chain in a strong electrolyte solution: Insight into equilibrium properties and force-extension behavior from mesoscale simulation
Authors: Malekzadeh Moghani Mahdy , Khomami Bamin
Published: January 2016

Macromolecules with ionizable groups are ubiquitous in biological and synthetic systems. Due to the complex interaction between chain and electrostatic decorrelation lengths, both equilibrium properties and micro-mechanical response of dilute solutions of polyelectrolytes (PEs) are more complex than their neutral counterparts. In this work, the bead-rod micromechanical description of a chain is used to perform hi-fidelity Brownian dynamics simulation of dilute PE solutions to ascertain the self-similar equilibrium behavior of PE chains with various linear charge densities, scaling of the Kuhn step length (lE) with salt concentration cs and the force-extension behavior of the PE chain. In accord with earlier theoretical predictions, our results indicate that for a chain with n Kuhn segments, lE ∼ cs−0.5 as linear charge density approaches 1/n. Moreover, the constant force ensemble simulation results accurately predict the initial non-linear force-extension region of PE chain recently measured via single chain experiments. Finally, inspired by Cohen’s extraction of Warner’s force law from the inverse Langevin force law, a novel numerical scheme is developed to extract a new elastic force law for real chains from our discrete set of force-extension data similar to Padè expansion, which accurately depicts the initial non-linear region where the total Kuhn length is less than the thermal screening length.
An instrument for charge measurement due to a single collision between two spherical particles
Authors: Xie L. , Bao N. , Jiang Y. , Han K. , Zhou J.
Published: January 2016

It universally exists in moving particular systems that particles can be electrified, in which the particles are chemically identical, just as toner particles, coal dust, and pharmaceutical powders. However, owing to the limit of experimental instruments, so far, there are yet no experiments to illustrate whether a particle can be electrified due to a single collision between two spherical particles, and there are also no experiments to measure the charge carried by a single particle due to a single collision between two particles. So we have developed an instrument for charge measurement due to a single collision between two spheres. The instrument consists of two-sphere collision device, collision charge measurement apparatus, and particles’ trajectory tracking system. By using this instrument, we can investigate the collision contact electrification due to a single collision between two spheres and simultaneously record the moving trajectories of spheres after the collision to calculate the rebound angles to identify the contribution of the triboelectrification due to the rubbing between the contact surfaces and the collision contact electrification due to the normal pressure between the contact surfaces.
Early-stage fault isolation based on frequency response fitted by small-size samples for cryogenic cold compressors with active magnetic bearings
Authors: Arpaia Pasquale , De Vito Luca , Girone Mario , Pezzetti Marco
Published: January 2016

A model-based method for fault detection and early-stage isolation, applicable when unfaulty conditions can be identified only by a reduced number of trials (even only one), is presented. The basic idea is to model analytically the uncertainty of the unfaulty frequency response and express the fault condition in terms of the noise power variance. A preliminary fault isolation is carried out by sensitivity analysis in order to identify the most influencing model parameters and assess their influence on the estimated noise. Then, during maintenance tests, the noise power is checked to detect the faulty condition. This technique is conceived to check the quality of a critical component in an experimental installation (fault detection and early-stage isolation), as well as to detect its faulty dynamic behaviors over a long horizon maintenance test campaign (condition monitoring). The method was applied to four cold compressors with active magnetic bearings at CERN by proving to be able to detect an actual faulty condition in one of such compressors.
Enhanced ferroelectric photoelectrochemical properties of polycrystalline BiFeO3 film by decorating with Ag nanoparticles
Authors: Liu Qing , Zhou Yang , You Lu , Wang Junling , Shen Mingrong , Fang Liang
Published: January 2016

Polycrystalline BiFeO3 (BFO) films are fabricated on Pt/Ti/SiO2/Si(100) substrate as photoelectrode using sol-gel method. The microstructure, optical, and photoelectrochemical (PEC) properties of the films are characterized and optimized by controlling the film thickness. Moreover, the PEC properties of the BFO films are dependent on ferroelectric polarization, which is mainly ascribed to the modulation of band structure at the BFO/electrolyte interface by the polarization. Further enhancement of PEC properties is obtained by decorating the samples with appropriate amounts of Ag nanoparticles, which is attributed to the reduced electron-hole recombination, and localized surface plasmon resonance effect of Ag nanoparticles.
Anisotropic subvoxel-smooth conduction model for bioelectromagnetism analysis
Authors: He Zhi Zhu , Liu Jing
Published: January 2016

The bioelectric conduction model plays a key role in bioelectromagnetism analysis, such as solving electromagnetic forward and inverse problems. This paper is aimed to develop an anisotropic subvoxel-smooth conduction model (ASCM) to characterize the electrical conductivity tensor jump across the tissue interface, which is derived based on the interfacial continuity condition with asymptotic analysis method. This conduction model is furthermore combined with finite volume method to improve the numerical accuracy for solving electromagnetic forward problem. The performance of ASCM for electrical potential analysis is verified by comparison with analytic solution. The method is also applied to investigate the effect of anisotropic conduction on EEG analysis in a realistic human head model.
Electroluminescence and cathodoluminescence from polyethylene and polypropylene films: Spectra reconstruction from elementary components and underlying mechanisms
Authors: Qiao B. , Teyssedre G. , Laurent C.
Published: January 2016

The mechanisms of electroluminescence from large band gap polymers used as insulation in electric components are still under debate. It becomes important to unravel the underlying physics of the emission because of increasing thermo-electric stress and a possible relationship between electroluminescence and field withstand. We report herein on the cathodoluminescence spectra of polyethylene and polypropylene films as a way to uncover the nature of its contributions to electroluminescence emission. It is shown that spectra from the two materials are structured around four elementary components, each of them being associated with a specific process contributing to the overall emission with different weights depending on excitation conditions and on materials. The cathodoluminescence and electroluminescence spectra of each material are reconstructed from the four spectral components and their relative contribution are discussed. It is shown that electroluminescence from polyethylene and polypropylene has the same origin pointing towards generic mechanisms in both.
A highly efficient bead extraction technique with low bead number for digital microfluidic immunoassay
Authors: Huang Cheng-Yeh , Tsai Po-Yen , Lee I-Chin , Hsu Hsin-Yun , Huang Hong-Yuan , Fan Shih-Kang , Yao Da-Jeng , Liu Cheng-Hsien , Hsu Wensyang
Published: January 2016

Here, we describe a technique to manipulate a low number of beads to achieve high washing efficiency with zero bead loss in the washing process of a digital microfluidic (DMF) immunoassay. Previously, two magnetic bead extraction methods were reported in the DMF platform: (1) single-side electrowetting method and (2) double-side electrowetting method. The first approach could provide high washing efficiency, but it required a large number of beads. The second approach could reduce the required number of beads, but it was inefficient where multiple washes were required. More importantly, bead loss during the washing process was unavoidable in both methods. Here, an improved double-side electrowetting method is proposed for bead extraction by utilizing a series of unequal electrodes. It is shown that, with proper electrode size ratio, only one wash step is required to achieve 98% washing rate without any bead loss at bead number less than 100 in a droplet. It allows using only about 25 magnetic beads in DMF immunoassay to increase the number of captured analytes on each bead effectively. In our human soluble tumor necrosis factor receptor I (sTNF-RI) model immunoassay, the experimental results show that, comparing to our previous results without using the proposed bead extraction technique, the immunoassay with low bead number significantly enhances the fluorescence signal to provide a better limit of detection (3.14 pg/ml) with smaller reagent volumes (200 nl) and shorter analysis time (<1 h). This improved bead extraction technique not only can be used in the DMF immunoassay but also has great potential to be used in any other bead-based DMF systems for different applications.
Raman characterization of damaged layers of 4H-SiC induced by scratching
Authors: Nakashima Shin-ichi , Mitani Takeshi , Tomobe Masaru , Kato Tomohisa , Okumura Hajime
Published: January 2016

Recent development of device fabrication of SiC is awaiting detailed study of the machining of the surfaces. We scratched 4H-SiC surfaces with a sliding microindenter made of a SiC chip, and characterized machining affected layers by micro-Raman spectroscopy. The results of the Raman measurement of the scratching grooves revealed that there were residual stress, defects, and stacking faults. Furthermore, with heavy scratching load, we found clusters of amorphous SiC, Si, amorphous carbon, and graphite in the scratching grooves. Analysis of the Raman spectra showed that SiC amorphization occurs first and surface graphitization (carbonization) is subsequently generated through the phase transformation of SiC. We expect that the Raman characterization of machined surfaces provides information on the machining mechanism for compound semiconductors.
Mapping spatial variability of leaf nutrient status of oil palm (Elaeis guineensis Jacq.) plantations in India
Authors: Behera S. K. , Suresh K. , Ramachandrudu K. , Manorama K. , Rao B. N.
Published: January 2016

Spatial variability of leaf nutrients in oil palm (Elaeis guineensis Jacq.) plantations in Goa, Karnataka, Mizoram and Gujarat states of India were examined for implementation of site-specific fertilisation programs. Georeferenced leaf samples were collected randomly for the oil palm plantations. The leaf nutrient concentrations were assessed and analysed statistically and geostatistically. The concentrations of leaf nutrients such as nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S) and boron (B) in oil palm plantations varied widely at different locations. Leaf P concentration was positively and significantly correlated with S concentration at Goa, Karnataka and Gujarat. Positive and significant correlation between leaf Ca and Mg concentration was recorded at Mizoram and Gujarat. Geostatistical analysis of leaf nutrients showed different distribution patterns at different locations. This study revealed the need to determine spatial variability of nutrient status of oil palm plantations before planning a differential fertiliser program. Therefore, saving of nutrients could be achieved by adopting site-specific nutrient-management strategies.
In vitro interaction between resistin and peroxisome proliferator-activated receptor γ in porcine ovarian follicles
Authors: Rak-Mardyła Agnieszka , Drwal Eliza
Published: January 2016

In the present study, using real-time polymerase chain reaction and immunoblotting methods, we quantified the expression of peroxisome proliferator-activated receptor (PPAR) γ, PPARα and PPARβ in different sized ovarian follicles (small (SF), medium (MF) and large (LF) follicles) in prepubertal and adult pigs. In prepubertal pigs, PPARγ and PPARα expression was highest in LF; however, PPARβ expression did not differ among SF, MF and LF. In mature pigs, only protein expression of PPARγ and PPARα increased during ovarian follicle development. Following identification of very high levels of PPARγ expression in LF in prepubertal and adult pigs, using in vitro culture of ovarian follicles, we determined the effect of resistin at 0.1, 1 and 10 ng mL–1 on PPARγ mRNA and protein expression and the effect of rosiglitazone at 25 and 50 µM (a PPARγ agonist) on resistin mRNA and protein expression. Resistin increased PPARγ expression in ovarian follicles in both prepubertal and adult pigs, whereas rosiglitazone had an inhibitory effect on resistin expression. The role of PPARγ in regulating the effects of resistin on ovarian steroidogenesis was investigated using GW9662 (a PPARγ antagonist at dose of 1 μM). In these studies, GW9662 reversed the effect of resistin on steroid hormone secretion. The data suggest that there is local cooperation between resistin and PPARγ expression in the porcine ovary. Resistin significantly increased the expression of PPARγ, whereas PPARγ decreased resistin expression; thus, PPARγ is a new key regulator of resistin expression and function.
Finite element analysis of laser beam-welded butt joints
Authors: Jiang T. , Wang K. , Zhang Z. M. , Fan W. , Zeng Y.
Published: January 2016

Thermal distortion of tailored blanks (TBs) during welding usually leads to a poor formability in the subsequent plastic deformation of TBs, and the welding distortion becomes especially serious in TBs consisting of different thickness plates. In this investigation, finite element method was applied to investigate the welding distortion of TBs with different thickness plates produced by laser beam welding. At the beginning, a 3D heat source model was built and verified by experimental results. Then, the following simulation results showed that the residual stresses generated in the thick plate side of the TBs were higher than those in the thin one. The varied reduction of heat input along the thickness direction for those two base plates can explain for this.
Spectral flow is a complete invariant for detecting bifurcation of critical points
Authors: Alexander James , Fitzpatrick Patrick
Published: January 2016

Given a one-parameter path of equations for which there is a trivial branch of solutions, to determine the points on the branch from which there bifurcate nontrivial solutions, there is the heuristic principle of linearization. That is to say, at each point on the branch, linearize the equation, and justify the inference that points on the branch that are bifurcation points for the path of linearized equations are also bifurcation points for the original path of equations. In quite general circumstances, for the bifurcation of critical points, we show that, at isolated singular points of the path of linearizations, a property of the path that is known to be sufficient to force bifurcation of nontrivial critical points is also necessary.

To be more precise, let

I
I

be an open interval of real numbers that contains the point

λ
0

\lambda _0

and

B
B

an open ball about the origin of a real, separable Hilbert space

H
.

H.

Let

ψ
:
I
×
B
→
 
R

\psi \colon I\times B\to \ R

be a family of

C
2

C^2

functions. For

λ
∈
I
,

\lambda \in I,

assume

∇
x

ψ
(
λ
,
0
)
=
0
,

\nabla _x\psi (\lambda ,0)=0,

and set

Hessian
x

⁡
ψ
(
λ
,

0
)
≡

L
λ

.

\operatorname {Hessian} _x\psi (\lambda ,\,0)\equiv L_\lambda .

Assume

L
λ

L_\lambda

is invertible if

λ
≠

λ
0

\lambda \ne \lambda _0

and

L

λ
0

L_{\lambda _0}

is Fredholm. It is known that if the spectral flow of

L
:
I
→

L

(
H
)

L\colon I\to {\mathcal L}(H)

across

λ
0

\lambda _0

is nonzero, then in each neighborhood of

(

λ
0

,

0
)

(\lambda _0,\,0)

there are pairs

(
λ
,

x
)
,

(\lambda ,\,x),

x
≠
0
,

x\ne 0,

for which

∇
x

ψ
(
λ
,
x
)
=
0.

\nabla _x\psi (\lambda ,x)=0.

We prove that if

L
:
I
→

L

(
H
)

L\colon I\to {\mathcal L}(H)

is a continuous path of symmetric operators for which

L
λ

L_\lambda

is invertible for

λ
≠

λ
0

,

\lambda \ne \lambda _0,

L

λ
0

L_{\lambda _0}

is Fredholm, and the spectral flow of

L
:
I
→

L

(
H
)

L\colon I\to {\mathcal L}(H)

across

λ
0

\lambda _0

is zero, then there is an open interval

J
J

that contains the point

λ
0

\lambda _0

, an open ball

B
B

about the origin, and a family

ψ
:
J
×
B
→
 
R

\psi \colon J\times B\to \ R

of

C
2

C^2

functions such that, for each

λ
∈
J
,

\lambda \in J,

∇
x

ψ
(
λ
,
0
)
=
0

\nabla _x\psi (\lambda ,0)=0

and

Hessian
x

⁡
ψ
(
λ
,

0
)
=

L
λ

,

\operatorname {Hessian} _x\psi (\lambda ,\,0)= L_\lambda ,

but

∇
x

ψ
(
λ
,
x
)
≠
0

\nabla _x\psi (\lambda ,x)\ne 0

if

x
≠
0.

x\ne 0.

Therefore, at an isolated singular point of the path of linearizations of the gradient, under the sole further assumption that the linearization at the singular point is Fredholm, spectral flow is a complete invariant for the detection of bifurcation of nontrivial critical points.
From resolvent estimates to unique continuation for the Schrödinger equation
Authors: Seo Ihyeok
Published: January 2016

In this paper we develop an abstract method to handle the problem of unique continuation for the Schrödinger equation

(
i

∂
t

+
Δ
)
u
=
V
(
x
)
u

(i\partial _t+\Delta )u=V(x)u

. In general the problem is to find a class of potentials

V
V

which allows the unique continuation. The key point of our work is to make a direct link between the problem and the weighted

L
2

L^2

resolvent estimates
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="double-vertical-bar left-parenthesis negative normal upper Delta minus z right-parenthesis Superscript negative 1 Baseline f double-vertical-bar Subscript upper L squared left-parenthesis StartAbsoluteValue upper V EndAbsoluteValue right-parenthesis Baseline less-than-or-equal-to upper C double-vertical-bar f double-vertical-bar Subscript upper L squared left-parenthesis StartAbsoluteValue upper V EndAbsoluteValue Sub Superscript negative 1 Subscript right-parenthesis">

‖
(
−
Δ
−
z

)

−
1

f

‖

L
2

(

|

V

|

)

≤
C
‖
f

‖

L
2

(

|

V

|

−
1

)

\|(-\Delta -z)^{-1}f\|_{L^2(|V|)}\leq C\|f\|_{L^2(|V|^{-1})}

. We carry it out in an abstract way, and thereby we do not need to deal with each of the potential classes. To do so, we will make use of the limiting absorption principle and Kato

H
H

-smoothing theorem in spectral theory, and employ some tools from harmonic analysis. Once the resolvent estimate is set up for a potential class, from our abstract theory the unique continuation would follow from the same potential class. Also, it turns out that there can be no dented surface on the boundary of the maximal open zero set of the solution

u
u

. In this regard, another main issue for us is to know which class of potentials allows the resolvent estimate. We establish such a new class which contains previously known ones, and we will also apply it to the problem of well-posedness for the equation.
Effects of high CO2 levels on the ecophysiology of the diatom Thalassiosira weissflogii differ depending on the iron nutritional status
Authors: Sugie Koji , Yoshimura Takeshi
Published: January 2016

Iron availability in seawater, namely the concentration of dissolved inorganic iron ([Fe′]), is affected by changes in pH. Such changes in the availability of iron should be taken into account when investigating the effects of ocean acidification on phytoplankton ecophysiology because iron plays a key role in phytoplankton metabolism. However, changes in iron availability in response to changes in ocean acidity are difficult to quantify specifically using natural seawater because these factors change simultaneously. In the present study, the availability of iron and carbonate chemistry were manipulated individually and simultaneously in the laboratory to examine the effect of each factor on phytoplankton ecophysiology. The effects of various pCO2 conditions (∼390, ∼600, and ∼800 µatm) on the growth, cell size, and elemental stoichiometry (carbon [C], nitrogen [N], phosphorus [P], and silicon [Si]) of the diatom Thalassiosira weissflogii under high iron ([Fe′] = ∼240 pmol l−1) and low iron ([Fe′] = ∼24 pmol l−1) conditions were investigated. Cell volume decreased with increasing pCO2, whereas intracellular C, N, and P concentrations increased with increasing pCO2 only under high iron conditions. Si:C, Si:N, and Si:P ratios decreased with increasing pCO2. It reflects higher production of net C, N, and P with no corresponding change in net Si production under high pCO2 and high iron conditions. In contrast, significant linear relationships between measured parameters and pCO2 were rarely detected under low iron conditions. We conclude that the increasing CO2 levels could affect on the biogeochemical cycling of bioelements selectively under the iron-replete conditions in the coastal ecosystems.
Possible Population III remnants at redshift 3.5
Authors: Crighton Neil H. M. , O'Meara John M. , Murphy Michael T.
Published: January 2016

The first stars, known as Population III (PopIII), produced the first heavy elements, thereby enriching their surrounding pristine gas. Previous detections of metals in intergalactic gas clouds, however, find a heavy element enrichment larger than 1/1000 times that of the solar environment, higher than expected for PopIII remnants. In this letter, we report the discovery of a Lyman limit system (LLS) at z = 3.53 with the lowest metallicity seen in gas with discernable metals, 10−3.41±0.26 times the solar value, at a level expected for PopIII remnants. We make the first relative abundance measurement in such low metallicity gas: the carbon-to-silicon ratio is 10−0.26±0.17 times the solar value. This is consistent with models of gas enrichment by a PopIII star formation event early in the Universe, but also consistent with later, Population II enrichment. The metals in all three components comprising the LLS, which has a velocity width of 400 km s−1, are offset in velocity by ∼+6 km s−1 from the bulk of the hydrogen, suggesting the LLS was enriched by a single event. Relative abundance measurements in this near-pristine regime open a new avenue for testing models of early gas enrichment and metal mixing.
Confrontation of top-hat spherical collapse against dark halos from cosmological N-body simulations
Authors: Suto Daichi , Kitayama Tetsu , Osato Ken , Sasaki Shin , Suto Yasushi
Published: January 2016

The top-hat spherical collapse model (TSC) is one of the most fundamental analytical frameworks to describe the non-linear growth of cosmic structure. TSC has motivated, and been widely applied in, various investigations even in the current era of precision cosmology. While numerous studies exist to examine its validity against numerical simulations in a statistical fashion, there are few analyses which compare the TSC dynamics in an individual object-wise basis, which is what we attempt in the present paper. We extract 100 halos at z = 0 from a cosmological N-body simulation according to the conventional TSC criterion for the spherical over-density. Then we trace back their spherical counterparts at earlier epochs. Just prior to the turn-around epoch of the halos, their dynamics are well approximated by TSC, but their turn-around epochs are systematically delayed and the virial radii are larger by ∼20% on average relative to the TSC predictions. We find that this systematic deviation can mainly be ascribed to the non-uniformity/inhomogeneity of dark matter density profiles and the non-zero velocity dispersions, both of which are neglected in TSC. In particular, the inside-out collapse and shell-crossing of dark matter halos play an important role in generating the significant velocity dispersion. The implications of the present result are briefly discussed.
Origin of the X-ray broad iron spectral feature in GRS 1915+105
Authors: Mizumoto Misaki , Ebisawa Ken , Tsujimoto Masahiro , Inoue Hajime
Published: January 2016

The X-ray spectrum of GRS 1915+105 is known to have a “broad iron spectral feature” in the spectral hard state. Similar spectral features are often observed in active galactic nuclei (AGNs) and other black-hole binaries (BHBs), and several models have been proposed for explaining it. In order to distinguish spectral models, time variation provides an important key. In AGNs, variation amplitude has been found to drop significantly at the iron K-energy band at timescales of ∼10 ks. If spectral variations of black holes are normalized by their masses, the spectral variations of BHBs on timescales of sub-seconds should exhibit similar characteristics to those of AGNs. In this paper, we investigated spectral variations of GRS 1915+105 at timescales down to ∼10 ms. This was made possible for the first time with the Suzaku XIS Parallel-sum clocking (P-sum) mode, which has the CCD energy-resolution as well as a time-resolution of 7.8 ms. Consequently, we found that the variation amplitude of GRS 1915+105 does not drop at the iron K-energy band on any timescales from 0.06 s to 63000 s, and that the entire X-ray flux and the iron feature are independently variable at timescales of hours. These are naturally understood in the framework of the “partial covering” model, in which variation timescales of the continuum flux and partial absorbers are independent. The difference of the energy dependence of the variation amplitude between AGNs and BHBs is presumably due to different mechanisms of the outflow winds, i.e., the partial absorbers are due to UV-line driven winds (AGNs) or thermally driven winds (BHBs).
Response of Sweet Sorghum Lines to Stalk Pathogens Fusarium thapsinum and Macrophomina phaseolina
Authors: Funnell-Harris Deanna L. , O’Neill Patrick M. , Sattler Scott E. , Yerka Melinda K.
Published: January 2016

Sweet sorghum (Sorghum bicolor (L.) Moench) has potential for bioenergy. It is adapted to a variety of U.S. locations and the extracted juice can be directly fermented into ethanol. However, little research on fungal stalk rots, diseases that pose serious constraints for yield and quality of juice and biomass, has been reported. A greenhouse bioassay was designed to assess charcoal rot (Macrophomina phaseolina) and Fusarium stalk rot (Fusarium thapsinum) in plants at maturity, the developmental stage at which these diseases are manifested. Multiple plantings of a susceptible grain line, RTx430, were used as a control for variation in flowering times among sweet sorghum lines. Lesion length measurements in inoculated peduncles were used to quantify disease severity. Sweet sorghum lines ‘Rio’ and ‘M81E’ exhibited resistance to F. thapsinum and M. phaseolina, respectively; and, in contrast, ‘Colman’ sorghum exhibited susceptibility to both pathogens. Lesion development over time in Colman was monitored. These results will enhance molecular and biochemical analyses of responses to pathogens, and breeding stalk-rot-resistant sweet sorghum lines.
Automating Assessment of the Undiscovered Biosynthetic Potential of Actinobacteria
Authors: Tokovenko Bogdan , Rebets Yuriy , Luzhetskyy Andriy
Published: January 2016

Background. Biosynthetic potential of Actinobacteria has long been the subject of theoretical estimates. Such an estimate is indeed important as a test of further exploitability of a taxon or group of taxa for new therapeutics. As neither a set of available genomes nor a set of bacterial cultivation methods are static, it makes sense to simplify as much as possible and to improve reproducibility of biosynthetic gene clusters similarity, diversity, and abundance estimations. Results. We have developed a command-line computational pipeline (available at https://bitbucket.org/qmentis/clusterscluster/) that assists in performing empirical (genome-based) assessment of microbial secondary metabolite gene clusters similarity and abundance, and applied it to a set of 208 complete and de-duplicated Actinobacteria genomes. After a brief overview of Actinobacteria biosynthetic potential as compared to other bacterial taxa, we use similarity thresholds derived from 4 pairs of known similar gene clusters to identify up to 40-48% of 3247 gene clusters in our set of genomes as unique. There is no saturation of the cumulative unique gene clusters curve within the examined dataset, and Heap's alpha is 0.129, suggesting an open pan-clustome. We identify and highlight pitfalls and possible improvements of genome-based gene cluster similarity measurements.
Recessive inactivating mutations in TBCK, encoding a Rab GTPase-activating protein that modulates mTOR signaling, cause severe infantile syndromic encephalopathy
Authors: Chong Jessica X , Caputo Viviana , Phelps Ian G , Stella Lorenzo , Worgan Lisa , Dempsey Jennifer C , Nguyen Alina , Leuzzi Vincenzo , Webster Richard , Pizzuti Antonio , Marvin Colby T , Ishak Gisele E , Ardern-Holmes Simone , Richmond Zara ,   Univ of Washington Center for Mendelian Genomics, Bamshad Michael J , Ortiz-Gonzalez Xilma R , Tartaglia Marco , Chopra Maya , Doherty Dan
Published: January 2016

Infantile encephalopathies are a group of clinically and biologically heterogeneous disorders for which the genetic basis remains largely unknown. Here, we report a previously unrecognized syndromic neonatal encephalopathy characterized by profound developmental disability, severe hypotonia, seizures, diminished respiratory drive requiring mechanical ventilation, brain atrophy, corpus callosum dysgenesis, cerebellar vermis hypoplasia, and facial dysmorphism. Biallelic inactivating mutations in TBCK (TBC1 domain-containing kinase) were independently identified by Whole-Exome Sequencing (WES) as the cause of this condition in four unrelated families. Matching these families was facilitated by sharing phenotypic profiles and WES data in a recently released web-based tool (Geno2MP) that links phenotypic information to rare variants in families with Mendelian traits. TBCK is a putative GTPase-activating protein (GAP) for small GTPases of the Rab family and has been shown to control cell growth and proliferation, actin cytoskeleton dynamics, and mTOR signaling. Two of the three mutations are predicted to truncate the protein (c.376C>T [p.Arg126*] and c.1363A>T [p.Lys455*]), and loss of the major TBCK isoform was confirmed in primary fibroblasts from one affected individual. The third mutation, c.1532G>A [p.Arg511His], alters a conserved residue within the TBC1 domain. Structural analysis implicates Arg511 as a required residue for Rab-GAP function, and in silico homology modeling predicts impaired GAP function in the corresponding mutant. These results suggest loss of Rab-GAP activity is the underlying mechanism of disease. In contrast to other disorders caused by dysregulated mTOR signaling associated with focal or global brain overgrowth, impaired TBCK function results in progressive loss of brain volume.
SDE and SPME Analysis of Flavor Compounds in Jin Xuan Oolong Tea
Authors: Sheibani Ershad , Duncan Susan E. , Kuhn David D. , Dietrich Andrea M. , O'Keefe Sean F.
Published: January 2016

Simultaneous distillation‐extraction (SDE) and solid phase micro extraction (SPME) are procedures used for the isolation of flavor compounds in foods. The purpose of this study was to optimize SDE conditions (solvent and time) and to compare SDE with SPME for the isolation of flavor compounds in Jin Xuan oolong tea using GC‐MS and GC‐O. The concentration of volatile compounds isolated with diethyl ether was higher (P < 0.05) than for dichloromethane and concentration was higher at 40 min (P < 0.05) than 20 or 60 min extractions. For SDE, 128 volatiles were identified using GC‐MS and 45 aroma active compounds using GC‐O. Trans‐nerolidol was the most abundant compound in oolong tea. The number of volatiles identified using GC‐MS was lower in SPME than SDE. For SPME, 59 volatiles and 41 aroma active compounds were identified. The composition of the volatiles isolated by the 2 methods differed considerably but provided complementary information.
Online advertising and privacy
Authors: de Cornière Alexandre , de Nijs Romain
Published: January 2016

An online platform auctions an advertising slot. Several advertisers compete in the auction, and consumers differ in their preferences. Prior to the auction, the platform decides whether to allow advertisers to access information about consumers (disclosure) or not (privacy). Disclosure improves the match between advertisers and consumers but increases product prices, even without price‐discrimination. We provide conditions under which disclosure or privacy is privately and/or socially optimal. When advertisers compete on the downstream market, disclosure can lead to an increase or a decrease in product prices depending on the nature of the information.
Ex post unbalanced tournaments
Authors: Imhof Lorens , Kräkel Matthias
Published: January 2016

Tournaments create strong incentives under the assumption that the competition between the agents is balanced. If, at the outset, one agent is stronger than the other, the tournament is ex ante unbalanced and incentives break down. Handicaps can in this case restore incentives. In practice, competing agents are often overall equally strong but have different sorts of strengths. Then, competition will typically be unbalanced ex post and incentives break down, but handicaps cannot be used. We show how a simple means, introducing the possibility of a tie, can often resolve the problem. We examine under what conditions incentives are maximized by ties.
When do auctions ensure the welfare‐maximizing allocation of scarce inputs?
Authors: Mayo John W. , Sappington David E.M.
Published: January 2016

We determine when an unfettered auction will ensure the welfare‐maximizing allocation of a scarce input that enhances product quality and may reduce production costs. A supplier values the input for this “use value” and for its “foreclosure value,” because once the input is acquired, it is unavailable to rivals. An unfettered auction often ensures the welfare‐maximizing allocation of an input increment. However, it can fail to do so when the input would increase relatively rapidly the competitive position of a rival with a moderate competitive disadvantage. Bidder handicapping that ensures auctions generate welfare‐maximizing input allocations differ from standard handicapping policies.
Health information technology and patient outcomes: the role of information and labor coordination
Authors: McCullough Jeffrey S. , Parente Stephen T. , Town Robert
Published: January 2016

Health information technology (IT) adoption, it is argued, will dramatically improve patient care. We study the impact of hospital IT adoption on patient outcomes focusing on the role of patient and organizational heterogeneity. We link detailed hospital discharge data on all Medicare fee‐for‐service admissions from 2002–2007 to detailed hospital‐level IT adoption information. For all IT‐sensitive conditions, we find that health IT adoption reduces mortality for the most complex patients but does not affect outcomes for the median patient. Benefits from health IT are primarily experienced by patients whose diagnoses require cross‐specialty care coordination and extensive clinical information management.
CB1 receptor blockade counters age‐induced insulin resistance and metabolic dysfunction
Authors: Lipina Christopher , Vaanholt Lobke M. , Davidova Anastasija , Mitchell Sharon E. , Storey‐Gordon Emma , Hambly Catherine , Irving Andrew J. , Speakman John R. , Hundal Harinder S.
Published: January 2016

The endocannabinoid system can modulate energy homeostasis by regulating feeding behaviour as well as peripheral energy storage and utilization. Importantly, many of its metabolic actions are mediated through the cannabinoid type 1 receptor (CB1R), whose hyperactivation is associated with obesity and impaired metabolic function. Herein, we explored the effects of administering rimonabant, a selective CB1R inverse agonist, upon key metabolic parameters in young (4 month old) and aged (17 month old) adult male C57BL/6 mice. Daily treatment with rimonabant for 14 days transiently reduced food intake in young and aged mice; however, the anorectic response was more profound in aged animals, coinciding with a substantive loss in body fat mass. Notably, reduced insulin sensitivity in aged skeletal muscle and liver concurred with increased CB1R mRNA abundance. Strikingly, rimonabant was shown to improve glucose tolerance and enhance skeletal muscle and liver insulin sensitivity in aged, but not young, adult mice. Moreover, rimonabant‐mediated insulin sensitization in aged adipose tissue coincided with amelioration of low‐grade inflammation and repressed lipogenic gene expression. Collectively, our findings indicate a key role for CB1R in aging‐related insulin resistance and metabolic dysfunction and highlight CB1R blockade as a potential strategy for combating metabolic disorders associated with aging.
Finding the clues
Authors: Young Andrew W.
Published: January 2016

Wu, Sheppard, and Mitchell (Br. J. Psychol., 2016; 107, 1–22) provide interesting data on the perception of empathy. Their focus on cue validity could usefully be expanded to look at what cues are used, whether they have multimodal properties, and how the perception of empathy relates to other first impressions.
Efficient versus flexible mentalizing in complex social settings: Exploring signature limits
Authors: Schneider Dana , Low Jason
Published: January 2016

Wu, Sheppard, and Mitchell (Br. J. Psychol., 2016; 107, 1–22) investigate in a fascinating study the fact that adults can detect empathic traits in others after only briefly watching or listening to a person. In this commentary, we highlight how the processes of an efficient, implicit, but inflexible mentalizing system are likely to operate in such situations. Further, we specify how testing signature limits over time‐, attribute‐, and protagonist‐restrictions can help distinguish whether an efficient‐implicit or flexible‐explicit mentalizing system is of relevance when processing complex social settings.
ROS in gastrointestinal inflammation: Rescue Or Sabotage?
Authors: Aviello G , Knaus UG
Published: January 2016

The intestine is composed of many distinct cell types that respond to commensal microbiota or pathogens with immune tolerance and proinflammatory signals respectively. ROS produced by mucosa‐resident cells or by newly recruited innate immune cells are essential for antimicrobial responses and regulation of signalling pathways including processes involved in wound healing. Impaired ROS production due to inactivating patient variants in genes encoding NADPH oxidases as ROS source has been associated with Crohn's disease and pancolitis, whereas overproduction of ROS due to up‐regulation of oxidases or altered mitochondrial function was linked to ileitis and ulcerative colitis. Here, we discuss recent advances in our understanding of how maintaining a redox balance is crucial to preserve gut homeostasis.

Linked Articles

This article is part of a themed section on Redox Biology and Oxidative Stress in Health and Disease. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.12/issuetoc