bluuebunny/crossref_metadata_2025 huggingface dataset:
Lifetime enhanced phosphorescent organic light emitting diode using an electron scavenger layer
Authors: Hong Seokhwan , Kim Ji Whan , Lee Sangyeob
Published: July 2015

We demonstrate a method to improve lifetime of a phosphorescent organic light emitting diode (OLED) using an electron scavenger layer (ESL) in a hole transporting layer (HTL) of the device. We use a bis(1-(phenyl)isoquinoline)iridium(III)acetylacetonate [Ir(piq)2(acac)] doped HTL to stimulate radiative decay, preventing thermal degradation in HTL. The ESL effectively prevented non-radiative decay of leakage electron in HTL by converting non-radiative decay to radiative decay via a phosphorescent red emitter, Ir(piq)2(acac). The lifetime of device (t95: time after 5% decrease of luminance) has been increased from 75 h to 120 h by using the ESL in a phosphorescent green-emitting OLED.
Experimental demonstration of high-order magnetic localized spoof surface plasmons
Authors: Gao Zhen , Gao Fei , Zhang Youming , Shi Xihang , Yang Zhaoju , Zhang Baile
Published: July 2015

We experimentally demonstrate that an ultrathin metallic spiral structure is able to support multiple high-order magnetic localized spoof surface plasmons (LSSPs), which were absent in previously reported magnetic LSSPs. Near-field response spectra and near-field mapping are performed in the microwave regime to confirm this phenomenon. We also show that the high-order magnetic LSSPs are more sensitive to the surrounding refractive index change than the previously reported magnetic dipole mode. Our study may be useful in electromagnetic near-field sensing from microwave to infrared frequencies.
Linear magnetoresistance without linear dispersions: The case of homogeneous silver deficient Ag2-δTe
Authors: Schnyders H. S.
Published: July 2015

We reproducibly vary the room temperature magnetoresistance (MR) of homogeneous, single-phase, polycrystalline silver telluride samples by precisely altering silver deficit with electrochemical doping. Deficit-tuned MR behaviors observed in fields typical of laboratory solenoids include sub-linearity, pure linearity, and MR(B) = α|B| + γB2, but higher field measurements reveal an MR saturation incongruous with linear dispersion-based MR models, and possibly suggestive of an alternate classical explanation involving three populations of carriers.
Parametric amplification of orbital angular momentum beams based on light-acoustic interaction
Authors: Gao Wei , Mu Chunyuan , Li Hongwei , Yang Yuqiang , Zhu Zhihan
Published: July 2015

A high fidelity amplification of beams carrying orbital angular momentum (OAM) is very crucial for OAM multiplexing and other OAM-based applications. Here, we report a demonstration of stimulated Brillouin amplification for OAM beams, and the energy conversion efficiency of photon-phonon coupling and the phase structure of amplified signals are investigated in collinear and noncollinear frame systems, respectively. Our results demonstrate that the OAM signals can be efficiently amplified without obvious noise introduced, and the modes of output signal are independent of the pump modes or the geometrical frames. Meanwhile, an OAM state depending on the optical modes and the geometrical frames is loaded into phonons by coherent light-acoustic interaction, which reveals more fundamental significance and a great application potential in OAM-multiplexing.
Communication: Non-monotonic evolution of dynamical heterogeneity in unfreezing process of metallic glasses
Authors: Li Y. Z. , Zhao L. Z. , Wang C. , Lu Z. , Bai H. Y. , Wang W. H.
Published: July 2015

The relaxation dynamics in unfreezing process of metallic glasses is investigated by the activation-relaxation technique. A non-monotonic dynamical microstructural heterogeneities evolution with temperature is discovered, which confirms and supplies more features to flow units concept of glasses. A flow unit perspective is proposed to microscopically describe this non-monotonic evolution of the dynamical heterogeneities as well as its relationship with the deformation mode development of metallic glasses.
The influence of charge and magnetic order on polaron and acoustic phonon dynamics in LuFe2O4
Authors: Lee J. , Trugman S. A. , Zhang C. L. , Talbayev D. , Xu X. S. , Cheong S.-W. , Yarotski D. A. , Taylor A. J. , Prasankumar R. P.
Published: July 2015

Femtosecond optical pump-probe spectroscopy is used to reveal the influence of charge and magnetic order on polaron dynamics and coherent acoustic phonon oscillations in single crystals of charge-ordered, ferrimagnetic LuFe2O4. We experimentally observed the influence of magnetic order on polaron dynamics. We also observed a correlation between charge order and the amplitude of the acoustic phonon oscillations, due to photoinduced changes in the lattice constant that originate from the photoexcited electrons. This provides insight into the general behavior of coherent acoustic phonon oscillations in charge-ordered materials.
Thermal infrared images to quantify thermal ablation effects of acid and base on target tissues
Authors: Liu Ran , Wang Jia , Liu Jing
Published: July 2015

Hyperthermia (42-46°C), treatment of tumor tissue through elevated temperature, offers several advantages including high cost-effectiveness, highly targeted ablation and fewer side effects and hence higher safety level over traditional therapies such as chemotherapy and radiotherapy. Recently, hyperthermia using heat release through exothermic acid-base neutralization comes into view owing to its relatively safe products of salt and water and highly confined ablation. However, lack of quantitative understanding of the spatial and temporal temperature profiles that are produced by simultaneous diffusion of liquid chemical and its chemical reaction within tumor tissue impedes the application of this method. This article is dedicated to quantify thermal ablation effects of acid and base both individually and as in neutralization via infrared captured thermal images. A theoretical model is used to approximate specific heat absorption rate (SAR) based on experimental measurements that contrast two types of tissue, normal pork and pig liver. According to the computation, both pork and liver tissue has a higher ability in absorbing hydrochloric acid (HCl) than sodium hydroxide, hence suggesting that a reduced dosage for HCl is appropriate in a surgery. The heating effect depends heavily on the properties of tissue types and amount of chemical reagents administered. Given thermal parameters such as SAR for different tissues, a computational model can be made in predicting temperature transitions which will be helpful in planning and optimizing surgical hyperthermia procedures.
Studies on structural, thermal and AC conductivity scaling of PEO-LiPF6 polymer electrolyte with added ionic liquid [BMIMPF6]
Authors: Chaurasia S. K. , Saroj A. L. , Shalu  , Singh V. K. , Tripathi A. K. , Gupta A. K. , Verma Y. L. , Singh R. K.
Published: July 2015

Preparation and characterization of polymer electrolyte films of PEO+10wt.% LiPF6 + xwt.% BMIMPF6 (1-butyl-3-methylimidazolium hexafluorophosphate) containing dopant salt lithium hexafluorophosphate (LiPF6) and ionic liquid (BMIMPF6) having common anion PF6- are reported. The ionic conductivity of the polymer electrolyte films has been found to increase with increasing concentration of BMIMPF6 in PEO+10 wt.% LiPF6 due to the plasticization effect of ionic liquid. DSC and XRD results show that the crystallinity of polymer electrolyte decreases with BMIMPF6 concentration which, in turn, is responsible for the increase in ionic conductivity. FTIR spectroscopic study shows the complexation of salt and/or ionic liquid cations with the polymer backbone. Ion dynamics behavior of PEO+LiPF6 as well as PEO+LiPF6 + BMIMPF6 polymer electrolytes was studied by frequency dependent conductivity, σ(f) measurements. The values σ(f) at various temperatures have been analyzed in terms of Jonscher power law (JPL) and scaled with respect to frequency which shows universal power law characteristics at all temperatures.
Change in equilibrium position of misfit dislocations at the GaN/sapphire interface by Si-ion implantation into sapphire. II. Electron energy loss spectroscopic study
Authors: Lee Sung Bo , Kim Young-Min , Han Heung Nam
Published: July 2015

In Part I, we have shown that the addition of Si into sapphire by ion implantationmakes the sapphire substrate elastically softer than for the undoped sapphire. The more compliant layer of the Si-implanted sapphire substrate can absorb the misfit stress at the GaN/sapphire interface, which produces a lower threading-dislocation density in the GaN overlayer. Here in Part II, based on experimental results by electron energy loss spectroscopy and a first-principle molecular orbital calculation in the literature, we suggest that the softening effect of Si results from a reduction of ionic bonding strength in sapphire (α-Al2O3) with the substitution of Si for Al.
Estimation of bodyweight from body measurements and determination of body measurements on Limousin cattle using digital image analysis
Authors: Ozkaya Serkan , Neja Wojciech , Krezel-Czopek Sylwia , Oler Adam
Published: July 2015

The objective of this study was to predict bodyweight and estimate body measurements of Limousin cattle using digital image analysis (DIA). Body measurements including body length, wither height, chest depth, and hip height of cattle were determined both manually (by measurements stick) and by using DIA. Body area was determined by using DIA. The images of Limousin cattle were taken while cattle were standing in a squeeze chute by a digital camera and analysed by image analysis software to obtain body measurements of each animal. While comparing the actual and predicted body measurements, the accuracy was determined as 98% for wither height, 97% for hip height, 94% for chest depth and 90.6% for body length. Regression analysis between body area and bodyweight yielded an equation with R2 of 61.5%. The regression equation, which included all body traits, resulted in an R2 value of 88.7%. The results indicated that DIA can be used for accurate prediction of body measurements and bodyweight of Limousin cattle.
Carbon-Doped Hollow Titania with Tuneable Shell Architecture for Supercapacitors
Authors: Chen Juanrong , Qiu Fengxian , Zhang Ying , Cao Shunsheng
Published: July 2015

A new trend in supercapacitor research has focussed on the construction of inexpensive electrode materials with high capacitor performances. In this study, we demonstrate the successful preparation of carbon-doped hollow titania spheres. The as-prepared titania spheres not only exhibit an advantage over existing methods because they are created in situ by directly carbonizing cationic polystyrene templates without the addition of carbon precursors, but also feature a narrow pore size distribution and a tuneable shell architecture. When the materials were applied as supercapacitor anodes, the electrochemical results reveal the superior performances of the supercapacitors over that of commercial P25. The higher performances were attributed to carbon doping. Thus, the reported C-doped hollow titania shows more potential as electrode materials for high-performance supercapacitors.
Isolation and characterisation of 14 polymorphic microsatellite loci for the plant-louse Trioza barrettae (Hemiptera : Triozidae)
Authors: Moir Melinda L. , Hitchen Yvette , Gardner Michael G. , Coates David J. , Kennington W. Jason
Published: July 2015

We describe the isolation and development of 14 polymorphic microsatellite loci for the critically endangered plant-louse Trioza barrettae (Hemiptera : Triozidae). The loci were tested in 25 individuals from a single population situated in the south-west of Western Australia. No evidence of linkage disequilibrium was detected between any pair of loci. However, eight loci showed significant departures from Hardy–Weinberg expectations. The number of alleles per locus ranged from 2 to 27.
Endothelial depletion of murine SRF/MRTF provokes intracerebral hemorrhagic stroke
Authors: Weinl Christine , Castaneda Vega Salvador , Riehle Heidemarie , Stritt Christine , Calaminus Carsten , Wolburg Hartwig , Mauel Susanne , Breithaupt Angele , Gruber Achim D. , Wasylyk Bohdan , Olson Eric N. , Adams Ralf H. , Pichler Bernd J. , Nordheim Alfred
Published: July 2015

Significance

Human cerebral small vessel disease (SVD) comprises age-associated intracerebral hemorrhages and global cognitive impairment, including vascular dementia. Human SVD presents in either familial or sporadic manifestation, involving either monogenic Mendelian defects or multitrait genetic variants. To better characterize the genetic and molecular mechanisms underlying SVD, appropriate animal models are needed. The
Srf

iECKO

mouse model presented here resembles human SVD pathology with regard to intracerebral hemorrhage formation and vascular dementia, including variability in onset and progression of cerebral symptoms. The Serum Response Factor (SRF)/Myocardin Related Transcription Factor (MRTF) are shown to regulate the expression of genes, which are essential for the maintenance of blood–brain barrier function and cerebral microvessel integrity. These findings suggest impairment of SRF/MRTF-mediated gene control as a molecular mechanism contributing to human SVD.
Essential roles of methionine and
S
-adenosylmethionine in the autarkic lifestyle of
Mycobacterium tuberculosis
Authors: Berney Michael , Berney-Meyer Linda , Wong Ka-Wing , Chen Bing , Chen Mei , Kim John , Wang Jingxin , Harris David , Parkhill Julian , Chan John , Wang Feng , Jacobs William R.
Published: July 2015

Significance

Mycobacterium tuberculosis
(
Mtb
) is the most deadly bacterial pathogen in the world, killing 1.5 million people in 2013. Very little is known about the way this pathogen interacts metabolically with its host to achieve long-term persistence and antibiotic tolerance. We uncovered a previously unknown metabolic vulnerability of
Mtb
, the absolute requirement for methionine and
S
-adenosylmethionine for successful host infection and virulence. Inactivation of methionine biosynthesis in
Mtb
leads to unusually rapid cell death, a highly desired feature for chemotherapy. Bactericidal auxotrophies are rare in
Mtb
, and so far their killing mechanisms have not been characterized systematically. Our study unravels a killing mechanism induced by amino acid starvation that leads to multitarget inhibition, opening new avenues for antimycobacterial interventions.
Dietary and non‐dietary correlates of gastrointestinal distress during the cycle and run of a triathlon
Authors: Wilson Patrick B.
Published: July 2015

The purpose of this investigation was to assess whether pre‐race dietary and non‐dietary factors were associated with gastrointestinal (GI) distress during the cycle and run of a 70.3‐mile triathlon. Fifty three participants recorded dietary details the day before and morning of the triathlon and retrospectively reported GI symptoms from the cycle and run. Occurrence and severity of nausea, regurgitation and fullness were combined into an upper GI (UGI) category, while lower abdominal cramps, flatulence and urge to defecate were combined into a lower GI (LGI) category. Spearman's rho coefficients were used to examine whether UGI and LGI were associated with: (1) pre‐race diet (kilocalories, carbohydrate, fibre, fat, protein, caffeine); and (2) non‐dietary factors (age, body mass index, experience, weight change, GI distress history, finishing time). Of non‐dietary factors, only a history of GI distress showed significant associations with GI symptoms during the triathlon (ρ =. 32–.36; P <. 05). Morning kilocalorie (ρ =. 28, P =. 04) and carbohydrate (ρ =. 36, P <. 01) intakes were modestly, positively associated with UGI during the cycle, while morning caffeine intake (ρ =. 30, P =. 03) showed a modest positive association with LGI during the run. The associations between diet and GI distress variables remained significant after adjusting for non‐dietary factors. Competitors of 70.3‐mile triathlons should carefully weigh the benefits of higher race‐morning energy, carbohydrate and caffeine intakes against their potential to increase GI distress.
SHORT- AND LONG-TERM RADIO VARIABILITY OF YOUNG STARS IN THE ORION NEBULA CLUSTER AND MOLECULAR CLOUD
Authors: Rivilla V. M. , Chandler C. J. , Sanz-Forcada J. , Jiménez-Serra I. , Forbrich J. , Martín-Pintado J.
Published: July 2015

We have used the Karl G. Jansky Very Large Array (VLA) to carry out multi-epoch radio continuum monitoring of the Orion Nebula Cluster (ONC) and the background Orion Molecular Cloud (OMC; 3 epochs at Q band and 11 epochs at Ka band). Our new observations reveal the presence of 19 radio sources, mainly concentrated in the Trapezium Cluster and the Orion Hot Core (OHC) regions. With the exception of the Becklin–Neugebauer object and source C (which we identify here as dust emission associated with a proplyd) the sources all show radio variability between the different epochs. We have found tentative evidence of variability in the emission from the massive object related to source I. Our observations also confirm radio flux density variations of a factor >2 on timescales of hours to days in five sources. One of these flaring sources, OHC-E, has been detected for the first time. We conclude that the radio emission can be attributed to two different components: (i) highly variable (flaring) non-thermal radio gyrosynchrotron emission produced by electrons accelerated in the magnetospheres of pre-main-sequence low-mass stars and (ii) thermal emission due to free–free radiation from ionized gas and/or heated dust around embedded massive objects and proplyds. Combining our sample with other radio monitoring at 8.3 GHz and the X-ray catalog provided by Chandra, we have studied the properties of the entire sample of radio/X-ray stars in the ONC/OMC region (51 sources). We have found several hints of a relation between the X-ray activity and the mechanisms responsible for (at least some fraction of) the radio emission. We have estimated a radio flaring rate of ∼0.14 flares day−1 in the dense stellar cluster embedded in the OHC region. This suggests that radio flares are more common events during the first stages of stellar evolution than previously thought. The advent of improved sensitivity with the new VLA and ALMA will dramatically increase the number of stars in young clusters detected at radio wavelengths, which will help us improve our understanding of the origin and nature of the radio emission.
Partial hyperbolicity and specification
Authors: Sumi Naoya , Varandas Paulo , Yamamoto Kenichiro
Published: July 2015

We study the specification property for partially hyperbolic dynamical systems. In particular, we show that if a partially hyperbolic diffeomorphism has two saddles with different indices, and the stable manifold of one of these saddles coincides with the strongly stable leaf, then it does not satisfy the specification property.
An optimal decay estimate for the linearized water wave equation in 2D
Authors: Bulut Aynur
Published: July 2015

We obtain a decay estimate for solutions to the linear dispersive equation

i

u
t

−
(
−
Δ

)

1

/

4

u
=
0

iu_t-(-\Delta )^{1/4}u=0

for

(
t
,
x
)
∈

R

×

R

(t,x)\in \mathbb {R}\times \mathbb {R}

. This corresponds to a factorization of the linearized water wave equation

u

t
t

+
(
−
Δ

)

1

/

2

u
=
0

u_{tt}+(-\Delta )^{1/2}u=0

. In particular, by making use of the Littlewood-Paley decomposition and stationary phase estimates, we obtain decay of order

|

t

|

−
1

/

2

|t|^{-1/2}

for solutions corresponding to data

u
(
0
)
=
φ

u(0)=\varphi

, assuming only bounds on

‖
φ

‖

H
x
1

(

R

)

\lVert \varphi \rVert _{H_x^1(\mathbb {R})}

and

‖
x

∂
x

φ

‖

L
x
2

(

R

)

\lVert x\partial _x\varphi \rVert _{L_x^2(\mathbb {R})}

. As another application of these ideas, we give an extension to equations of the form

i

u
t

−
(
−
Δ

)

α

/

2

u
=
0

iu_t-(-\Delta )^{\alpha /2}u=0

for a wider range of

α
\alpha

.
The Poisson distribution, abstract fractional difference equations, and stability
Authors: Lizama Carlos
Published: July 2015

We study the initial value problem
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="StartLayout 1st Row with Label left-parenthesis asterisk right-parenthesis EndLabel StartLayout Enlarged left-brace 1st Row 1st Column Subscript upper C Baseline normal upper Delta Superscript alpha Baseline u left-parenthesis n right-parenthesis 2nd Column a m p semicolon equals upper A u left-parenthesis n plus 1 right-parenthesis comma n element-of double-struck upper N 0 semicolon 2nd Row 1st Column u left-parenthesis 0 right-parenthesis 2nd Column a m p semicolon equals u 0 element-of upper X comma EndLayout EndLayout">

(

∗

)

{

C

Δ

α

u
(
n
)

a
m
p
;
=
A
u
(
n
+
1
)
,

n
∈

N

0

;

u
(
0
)

a
m
p
;
=

u
0

∈
X
,

\begin{equation*} \tag {$*$} \left \{\begin {array}{rll} _C\Delta ^{\alpha } u(n) &= Au(n+1), \quad n \in \mathbb {N}_0; \\ u(0) &= u_0 \in X, \end{array}\right . \end{equation*}

when

A
A

is a closed linear operator with domain

D
(
A
)

D(A)

defined on a Banach space

X
X

. We introduce a method based on the Poisson distribution to show existence and qualitative properties of solutions for the problem

(
∗
)

(*)

, using operator-theoretical conditions on

A
A

. We show how several properties for fractional differences, including their own definition, are connected with the continuous case by means of sampling using the Poisson distribution. We prove necessary conditions for stability of solutions, that are only based on the spectral properties of the operator

A
A

in the case of Hilbert spaces.
On a stopping game in continuous time
Authors: Bayraktar Erhan , Zhou Zhou
Published: July 2015

On a filtered probability space
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="left-parenthesis normal upper Omega comma script upper F comma upper P comma double-struck upper F equals left-parenthesis script upper F Subscript t Baseline right-parenthesis Subscript 0 less-than-or-equal-to t less-than-or-equal-to upper T Baseline right-parenthesis">

(
Ω
,

F

,
P
,

F

=
(

F

t

)

0
≤
t
≤
T

)

(\Omega ,\mathcal {F},P,\mathbb {F}=(\mathcal {F}_t)_{0\leq t\leq T})

, we consider stopper-stopper games
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper C overbar colon equals inf Underscript bold-italic rho Endscripts sup Underscript tau element-of script upper T Endscripts double-struck upper E left-bracket upper U left-parenthesis bold-italic rho left-parenthesis tau right-parenthesis comma tau right-parenthesis right-bracket">

C
¯

:=

inf

ρ

sup

τ
∈

T

E

[
U
(
ρ
(
τ
)
,
τ
)
]

\overline C:=\inf _{\boldsymbol {\rho }}\sup _{\tau \in \mathcal {T}} \mathbb {E}[U(\boldsymbol {\rho }(\tau ),\tau )]

and

C
_

:=

\underline C:=

<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="sup Underscript bold-italic tau Endscripts inf Underscript rho element-of script upper T Endscripts double-struck upper E left-bracket upper U left-parenthesis rho comma bold-italic tau left-parenthesis rho right-parenthesis right-parenthesis right-bracket">

sup

τ

inf

ρ
∈

T

E

[
U
(
ρ
,
τ
(
ρ
)
)
]

\sup _{\boldsymbol {\tau }} \inf _{\rho \in \mathcal {T}}\mathbb {E}[U(\rho ,\boldsymbol {\tau } (\rho ))]

in continuous time, where

U
(
s
,
t
)

U(s,t)

is

F

s
∨
t

\mathcal {F}_{s\vee t}

-measurable (this is the new feature of our stopping game),

T

\mathcal {T}

is the set of stopping times, and

ρ
,
τ
:

T

↦

T

\boldsymbol {\rho },\boldsymbol {\tau }:\mathcal {T} \mapsto \mathcal {T}

satisfy certain non-anticipativity conditions. We show that

C
¯

=

C
_

\overline C=\underline C

, by converting these problems into a corresponding Dynkin game.
Effects of Glaucoma Tube Surgery on Corneal Endothelial Cells: A Review
Authors: Koo Euna B. , Hou Jing , Keenan Jeremy D. , Stamper Robert L. , Jeng Bennie H. , Han Ying
Published: July 2015

The etiology of corneal decompensation after aqueous shunt implantation remains poorly understood. With the use of anterior segment optical coherence tomography and specular microscopy, the relationship of these implants to the surrounding tissues can be investigated over time. This article will review the current knowledge pertaining to endothelial cell loss related to glaucoma and surgery and highlight possible causes that have been proposed for endothelial cell loss after aqueous shunt implantation.
Happy hamsters? Enrichment induces positive judgement bias for mildly (but not truly) ambiguous cues to reward and punishment inMesocricetus auratus
Authors: Bethell Emily J. , Koyama Nicola F.
Published: July 2015

Recent developments in the study of animal cognition and emotion have resulted in the ‘judgement bias’ model of animal welfare. Judgement biases describe the way in which changes in affective state are characterized by changes in information processing. In humans, anxiety and depression are characterized by increased expectation of negative events and negative interpretation of ambiguous information. Positive wellbeing is associated with enhanced expectation of positive outcomes and more positive interpretation of ambiguous information. Mood-congruent judgement biases for ambiguous information have been demonstrated in a range of animal species, with large variation in the way tests are administered and in the robustness of analyses. We highlight and address some issues using a laboratory species not previously tested: the Syrian hamster (Mesocricetus auratus). Hamsters were tested using a spatial judgement go/no-go task in enriched and unenriched housing. We included a number of controls and additional behavioural tests and applied a robust analytical approach using linear mixed effects models. Hamsters approached the ambiguous cues significantly more often when enriched than unenriched. There was no effect of enrichment on responses to the middle cue. We discuss these findings in light of mechanisms underlying processing cues to reward, punishment and true ambiguity, and the implications for the welfare of laboratory hamsters.
Regional differentiation and extensive hybridization between mitochondrial clades of the Southern Ocean giant sea spider
Colossendeis megalonyx
Authors: Dietz Lars , Arango Claudia P. , Dömel Jana S. , Halanych Kenneth M. , Harder Avril M. , Held Christoph , Mahon Andrew R. , Mayer Christoph , Melzer Roland R. , Rouse Greg W. , Weis Andrea , Wilson Nerida G. , Leese Florian
Published: July 2015

Assessing the enormous diversity of Southern Ocean benthic species and their evolutionary histories is a central task in the era of global climate change. Based on mitochondrial markers, it was recently suggested that the circumpolar giant sea spider
Colossendeis megalonyx
comprises a complex of at least six cryptic species with mostly small and non-overlapping distribution ranges. Here, we expand the sampling to include over 500 mitochondrial COI sequences of specimens from around the Antarctic. Using multiple species delimitation approaches, the number of distinct mitochondrial OTUs increased from six to 15–20 with our larger dataset. In contrast to earlier studies, many of these clades show almost circumpolar distributions. Additionally, analysis of the nuclear internal transcribed spacer region for a subset of these specimens showed incongruence between nuclear and mitochondrial results. These mito-nuclear discordances suggest that several of the divergent mitochondrial lineages can hybridize and should not be interpreted as cryptic species. Our results suggest survival of
C. megalonyx
during Pleistocene glaciations in multiple refugia, some of them probably located on the Antarctic shelf, and emphasize the importance of multi-gene datasets to detect the presence of cryptic species, rather than their inference based on mitochondrial data alone.
Symbiotic bacteria enable olive fly larvae to overcome host defences
Authors: Ben-Yosef Michael , Pasternak Zohar , Jurkevitch Edouard , Yuval Boaz
Published: July 2015

Ripe fruit offer readily available nutrients for many animals, including fruit fly larvae (Diptera: Tephritidae) and their associated rot-inducing bacteria. Yet, during most of their ontogeny, fruit remain chemically defended and effectively suppress herbivores and pathogens by high levels of secondary metabolites. Olive flies (Bactrocera oleae) are uniquely able to develop in unripe olives. Unlike other frugivorous tephritids, the larvae maintain bacteria confined within their midgut caeca. We examined the interaction between larvae, their associated bacteria, and fruit chemical defence, hypothesizing that bacterial contribution to larval development is contingent on the phenology of fruit defensive chemistry. We demonstrate that larvae require their natural complement of bacteria (CandidatusErwinia dacicola: Enterobacteriaceae) in order to develop in unripe olives. Conversely, when feeding on ripe fruit, larval development proceeds independently of these bacteria. Our experiments suggest that bacteria counteract the inhibitory effect of oleuropein—the principal phenolic glycoside in unripe olives. In light of these results, we suggest that the unique symbiosis in olive flies, compared with other frugivorous tephritids, is understood by considering the relationship between the fly, bacteria and fruit chemistry. When applied in an evolutionary context, this approach may also point out the forces which shaped symbioses across the Tephritidae.
The presence of lateral photophores correlates with increased speciation in deep-sea bioluminescent sharks
Authors: Claes Julien M. , Nilsson Dan-Eric , Mallefet Jérôme , Straube Nicolas
Published: July 2015

The vast majority of species within the lanternshark genus
Etmopterus
harbour complex luminescent markings on their flanks, whose functional significance has long remained obscure. Recent studies, however, suggest these enigmatic photophore aggregations to play a role in intraspecific communication. Using visual modelling based on
in vivo
luminescence measurements from a common lanternshark species, we show that etmopterid flank markings can potentially work as a medium range signal for intraspecific detection/recognition. In addition, using molecular phylogenetic analyses, we demonstrate that the
Etmopterus
clade exhibits a greater than expected species richness given its age. This is not the case for other bioluminescent shark clades with no (or only few) species with flank markings. Our results therefore suggest that etmopterid flank markings may provide a way for reproductive isolation and hence may have facilitated speciation in the deep-sea.
Effects of thickness and fibre misalignment on compression fracture in cross-ply (very) long cylindrical shells under external pressure
Authors: Chaudhuri Reaz A.
Published: July 2015

Combined effects of modal imperfections, transverse shear/normal deformation with/without reduced transverse shear modulus,
G
LT
(caused by distributed fibre misalignments), on emergence of interlaminar shear crippling type instability modes, related to localization (onset of deformation softening), delocalization (onset of deformation hardening) and propagation of mode II compression fracture/damage, in thick imperfect cross-ply very long cylindrical shells (plane strain rings) under applied hydrostatic pressure, are investigated. Of special interest is the question: what are the geometric and/or material parameters that induce localized and delocalized states in imperfect cross-ply (very) long cylindrical shells under hydrostatic compression simultaneously, and what would be the consequences of such occurrences? The primary accomplishment is the (hitherto unavailable) computation of the layer-wise mode II stress intensity factor, energy release rate and kink–crack bandwidth, under hydrostatic compression, from a nonlinear finite-element analysis, using Maxwell's construction and Griffith's energy balance approach. Additionally, the shear crippling angles in the layers are determined using an analysis, pertaining to the elastic inextensional deformation of the compressed (plane strain) ring. Numerical results include effects of (i) thickness-induced transverse shear/normal deformation and (ii) uniformly distributed fibre misalignments, on localization and delocalization, and consequently on compression fracture/damage characteristics of thick imperfect cross-ply very long cylindrical shells.
The Darboux transformation of the Kundu–Eckhaus equation
Authors: Qiu Deqin , He Jingsong , Zhang Yongshuai , Porsezian K.
Published: July 2015

We construct an analytical and explicit representation of the Darboux transformation (DT) for the Kundu–Eckhaus (KE) equation. Such solution andn-fold DTTnare given in terms of determinants whose entries are expressed by the initial eigenfunctions and ‘seed’ solutions. Furthermore, the formulae for the higher order rogue wave (RW) solutions of the KE equation are also obtained by using the Taylor expansion with the use of degenerate eigenvaluesλ2k−1→λ1=−12a+βc2+ic,k=1,2,3,…, all these parameters will be defined latter. These solutions have a parameterβ, which denotes the strength of the non-Kerr (quintic) nonlinear and the self-frequency shift effects. We apply the contour line method to obtain analytical formulae of the length and width for the first-order RW solution of the KE equation, and then use it to study the impact of theβon the RW solution. We observe two interesting results on localization characters ofβ, such that ifβis increasing froma/2: (i) the length of the RW solution is increasing as well, but the width is decreasing; (ii) there exist a significant rotation of the RW along the clockwise direction. We also observe the oppositely varying trend ifβis increasing toa/2. We define an area of the RW solution and find that this area associated withc=1 is invariant whenaandβare changing.
Energy-based non-local plasticity models for deformation patterning, localization and fracture
Authors: Lancioni Giovanni , Yalçinkaya Tuncay , Cocks Alan
Published: July 2015

This paper analyses the effect of the form of the plastic energy potential on the (heterogeneous) distribution of the deformation field in a simple setting where the key physical aspects of the phenomenon could easily be extracted. This phenomenon is addressed through two different (rate-dependent and rate-independent) non-local plasticity models, by numerically solving two distinct one-dimensional problems, where the plastic energy potential has different non-convex contributions leading to patterning of the deformation field in a shear problem, and localization, resulting ultimately in fracture, in a tensile problem. Analytical and numerical solutions provided by the two models are analysed, and they are compared with experimental observations for certain cases.
Pervasive and strong effects of plants on soil chemistry: a meta-analysis of individual plant ‘Zinke’ effects
Authors: Waring Bonnie G. , Álvarez-Cansino Leonor , Barry Kathryn E. , Becklund Kristen K. , Dale Sarah , Gei Maria G. , Keller Adrienne B. , Lopez Omar R. , Markesteijn Lars , Mangan Scott , Riggs Charlotte E. , Rodríguez-Ronderos María Elizabeth , Segnitz R. Max , Schnitzer Stefan A. , Powers Jennifer S.
Published: July 2015

Plant species leave a chemical signature in the soils below them, generating fine-scale spatial variation that drives ecological processes. Since the publication of a seminal paper on plant-mediated soil heterogeneity by Paul Zinke in 1962, a robust literature has developed examining effects of individual plants on their local environments (individual plant effects). Here, we synthesize this work using meta-analysis to show that plant effects are strong and pervasive across ecosystems on six continents. Overall, soil properties beneath individual plants differ from those of neighbours by an average of 41%. Although the magnitudes of individual plant effects exhibit weak relationships with climate and latitude, they are significantly stronger in deserts and tundra than forests, and weaker in intensively managed ecosystems. The ubiquitous effects of plant individuals and species on local soil properties imply that individual plant effects have a role in plant–soil feedbacks, linking individual plants with biogeochemical processes at the ecosystem scale.
The extended Price equation quantifies species selection on mammalian body size across the Palaeocene/Eocene Thermal Maximum
Authors: Rankin Brian D. , Fox Jeremy W. , Barrón-Ortiz Christian R. , Chew Amy E. , Holroyd Patricia A. , Ludtke Joshua A. , Yang Xingkai , Theodor Jessica M.
Published: July 2015

Species selection, covariation of species’ traits with their net diversification rates, is an important component of macroevolution. Most studies have relied on indirect evidence for its operation and have not quantified its strength relative to other macroevolutionary forces. We use an extension of the Price equation to quantify the mechanisms of body size macroevolution in mammals from the latest Palaeocene and earliest Eocene of the Bighorn and Clarks Fork Basins of Wyoming. Dwarfing of mammalian taxa across the Palaeocene/Eocene Thermal Maximum (PETM), an intense, brief warming event that occurred at approximately 56 Ma, has been suggested to reflect anagenetic change and the immigration of small bodied-mammals, but might also be attributable to species selection. Using previously reconstructed ancestor–descendant relationships, we partitioned change in mean mammalian body size into three distinct mechanisms: species selection operating on resident mammals, anagenetic change within resident mammalian lineages and change due to immigrants. The remarkable decrease in mean body size across the warming event occurred through anagenetic change and immigration. Species selection also was strong across the PETM but, intriguingly, favoured larger-bodied species, implying some unknown mechanism(s) by which warming events affect macroevolution.
Costs of CRISPR-Cas-mediated resistance inStreptococcus thermophilus
Authors: Vale Pedro F. , Lafforgue Guillaume , Gatchitch Francois , Gardan Rozenn , Moineau Sylvain , Gandon Sylvain
Published: July 2015

CRISPR-Cas is a form of adaptive sequence-specific immunity in microbes. This system offers unique opportunities for the study of coevolution between bacteria and their viral pathogens, bacteriophages. A full understanding of the coevolutionary dynamics of CRISPR-Cas requires knowing the magnitude of the cost of resisting infection. Here, using the gram-positive bacteriumStreptococcus thermophilusand its associated virulent phage 2972, a well-established model system harbouring at least two type II functional CRISPR-Cas systems, we obtained different fitness measures based on growth assays in isolation or in pairwise competition. We measured the fitness cost associated with different components of this adaptive immune system: the cost of Cas protein expression, the constitutive cost of increasing immune memory through additional spacers, and the conditional costs of immunity during phage exposure. We found that Cas protein expression is particularly costly, as Cas-deficient mutants achieved higher competitive abilities than the wild-type strain with functional Cas proteins. Increasing immune memory by acquiring up to four phage-derived spacers was not associated with fitness costs. In addition, the activation of the CRISPR-Cas system during phage exposure induces significant but small fitness costs. Together these results suggest that the costs of the CRISPR-Cas system arise mainly due to the maintenance of the defence system. We discuss the implications of these results for the evolution of CRISPR-Cas-mediated immunity.
Adaptive Evolution for Increased Biomass and Magnetic Nanoparticle Productivity of Magnetotactic Bacteria
Authors: Sekar Karthik , Oza Javin P
Published: July 2015

Large magnetic nanoparticles (over 25 nm diameter) are a valuable commodity but remain difficult to synthesize using traditional chemical synthesis methods. Magnetotactic bacteria (MTBs) have evolved mechanisms to produce monodisperse, protected magnetic nanostructures within organelles (magnetosomes). Genomic diversity of MTB species result in unique particle properties that vary in shape and size ranging from 30 nm to 150 nm based on the genetic background. Culturing and engineering MTBs for the production of magnetic nanoparticles carries tremendous potential but is underdeveloped. This primarily because MTBs are difficult to culture and genetically manipulate, limitations that could be alleviated with adaptive evolution. We propose the magnetotrophic reactor, a novel bioreactor system for adaptively evolving MTBs for better growth and magnetosome production. This platform is projected to be superior to the traditional evolution methods since robust growth phenotypes can be selected for while maintaining selective pressure for magnetotaxis. We provide, herein, a quantitative basis for our platform including considerations of continuous evolution, sizing, and magnetic field pulsing. Our proposed fermentation process anticipates scalable production of 1 g/L per day of monodisperse magnetic nanoparticles to enable industrial applications.
Phenotypic analysis of Arabidopsis transgenic plants constitutively expressing the P6 protein fromCauliflower mosaic virusor mutant alleles thereof
Authors: Geldreich Angèle , Himber Christophe , Haas Gabrielle , Keller Mario , Voinnet Olivier
Published: July 2015

This laboratory has previously shown that nuclear import of CaMV P6 is required for infection and suppression of the RNA silencing factor DRB4. EMBO J., 27:2102 - 2112. In the original paper, there were inadvertent errors in the mounting of a figure. We have now repeated the experiments concerned, using the seed stock of the corresponding transgenic plants. The results presented here confirm those reported in the original paper. The plants expressing P6 are strongly stunted with chlorotic and serrated leaves. Conversely, the transgenic expression of various P6 mutant alleles do not induce this phenotype.
A rapid and tunable method to temporally control Cas9 expression enables the identification of essential genes and the interrogation of functional gene interactions in vitro and in vivo
Authors: Senturk Serif , Shirole Nitin H. , Nowak Dawid D. , Corbo Vincenzo , Vaughan Alexander , Tuveson David A. , Trotman Lloyd C. , Kepecs Adam , Stegmeier Frank , Sordella Raffaella
Published: July 2015

The Cas9/CRISPR system is a powerful tool for studying gene function. Here we describe a method that allows temporal control of Cas9/CRISPER activity based on conditional Cas9 destabilization. We demonstrate that fusing an FKBP12-derived destabilizing domain to Cas9 (DD-CAS9) enables conditional Cas9 expression in vitro in the presence of an FKBP12 synthetic ligand and temporal control of gene-editing. Further, we show that this strategy can be easily adapted to co-express, from the same promoter, DD-Cas9 with any other gene of interest, without the latter being co-modulated. In particular, when co-expressed with inducible Cre-ERT2, our system enables parallel, independent manipulation of alleles targeted by Cas9 and traditional recombinase with single-cell specificity. We anticipate this platform will be used for the systematic identification of essential genes and the interrogation of genes functional interactions.
Crowdsourced geometric morphometrics enable rapid large-scale collection and analysis of phenotypic data
Authors: Chang Jonathan , Alfaro Michael E
Published: July 2015

1. Advances in genomics and informatics have enabled the production of large phylogenetic trees. However, the ability to collect large phenotypic datasets has not kept pace. 2. Here, we present a method to quickly and accurately gather morphometric data using crowdsourced image-based landmarking. 3. We find that crowdsourced workers perform similarly to experienced morphologists on the same digitization tasks. We also demonstrate the speed and accuracy of our method on seven families of ray-finned fishes (Actinopterygii). 4. Crowdsourcing will enable the collection of morphological data across vast radiations of organisms, and can facilitate richer inference on the macroevolutionary processes that shape phenotypic diversity across the tree of life.
Risk aversion and effort under an incentive pay scheme with multiplicative noise
Authors: Zubanov Nikolay
Published: July 2015

Purpose

– The purpose of this paper is to consider the influence of individual risk preferences on the effectiveness of incentive pay schemes, by examining the link between individual effort and risk aversion in situations where outcome uncertainty multiplies with effort. Such “multiplicative noise” situations are common, occurring whenever payment is awarded per success rather than per attempt.

Design/methodology/approach

– The paper develops a theoretical model which predicts a negative risk aversion-effort link under multiplicative noise without a performance target (PT), and a weaker negative link once the target is introduced. This model is then taken to the data from a lab experiment where participants were randomly assigned to a control group, which received fixed pay, and a treatment group, which received a piece rate awarded with a certain probability, with and without a PT. Risk aversion is measured with a menu of lottery choices offered at the end of the experiment.

Findings

– Compared to their peers in the control group, the more risk-averse participants in the treatment group put in progressively less effort in the absence of a PT. The introduction of a PT substantially weakens this negative risk aversion-effort link, so that there are no more significant differences in performance between the more and the less risk averse.

Research limitations/implications

– The paper’s findings speak to the empirical puzzles of incentive pay schemes backfiring and of the proliferation of PTs. The negative risk aversion-effort link may be one reason behind the failure of incentive schemes to deliver improved performance, whereas the weakening of this link may be one justification for the existence of PTs.

Practical implications

– In the multiplicative noise environments, managers should take their workers’ risk preferences into account when designing incentive pay schemes. A PT may be a useful motivational tool for the risk-averse workers who are more likely to under-perform.

Originality/value

– The multiplicative noise environment has been largely overlooked by the existing literature, yet it is common in practice. An example is the work of a sales agent who receives a bonus per sales which succeeds with a certain probability after each customer contact. This paper is one of the first to model, and test experimentally, worker performance in this environment.