bluuebunny/crossref_metadata_2025 huggingface dataset:
Self-consistent phonon theory of the crystallization and elasticity of attractive hard spheres
Authors: Shin Homin , Schweizer Kenneth S.
Published: February 2013

We propose an Einstein-solid, self-consistent phonon theory for the crystal phase of hard spheres that interact via short-range attractions. The approach is first tested against the known behavior of hard spheres, and then applied to homogeneous particles that interact via short-range square well attractions and the Baxter adhesive hard sphere model. Given the crystal symmetry, packing fraction, and strength and range of attractive interactions, an effective harmonic potential experienced by a particle confined to its Wigner-Seitz cell and corresponding mean square vibrational amplitude are self-consistently calculated. The crystal free energy is then computed and, using separate information about the fluid phase free energy, phase diagrams constructed, including a first-order solid-solid phase transition and its associated critical point. The simple theory qualitatively captures all the many distinctive features of the phase diagram (critical and triple point, crystal-fluid re-entrancy, low-density coexistence curve) as a function of attraction range, and overall is in good semi-quantitative agreement with simulation. Knowledge of the particle localization length allows the crystal shear modulus to be estimated based on elementary ideas. Excellent predictions are obtained for the hard sphere crystal. Expanded and condensed face-centered cubic crystals are found to have qualitatively different elastic responses to varying attraction strength or temperature. As temperature increases, the expanded entropic solid stiffens, while the energy-controlled, fully-bonded dense solid softens.
Synthesis, structural, thermal and optical studies of inorganic-organic hybrid semiconductors, R-PbI4
Authors: Pradeesh K. , Nageswara Rao K. , Vijaya Prakash G.
Published: February 2013

Wide varieties of naturally self-assembled two-dimensional inorganic-organic (IO) hybrid semiconductors, (4-ClC6H4NH3)2PbI4, (C6H9C2H4NH3)2PbI4, (CnH2n+1NH3)2PbI4 (where n = 12, 16, 18), (CnH2n-1NH3)2PbI4 (where n = 3, 4, 5), (C6H5C2H4NH3)2PbI4, NH3(CH2)12NH3PbI4, and (C4H3SC2H4NH3)2PbI4, were fabricated by intercalating structurally diverse organic guest moieties into lead iodide perovskite structure. The crystal packing of all these fabricated IO-hybrids comprises of well-ordered organic and inorganic layers, stacked-up alternately along c-axis. Almost all these hybrids are thermally stable upto 200 °C and show strong room-temperature exciton absorption and photoluminescence features. These strongly confined optical excitons are highly influenced by structural deformation of PbI matrix due to the conformation of organic moiety. A systematic correlation of optical exciton behavior of IO-hybrids with the organic/inorganic layer thicknesses, intercalating organic moieties, and various structural disorders were discussed. This systematic study clearly suggests that the PbI layer crumpling is directly responsible for the tunability of optical exciton energy.
Convectons and secondary snaking in three-dimensional natural doubly diffusive convection
Authors: Beaume Cédric , Bergeon Alain , Knobloch Edgar
Published: February 2013

Natural doubly diffusive convection in a three-dimensional vertical enclosure with square cross-section in the horizontal is studied. Convection is driven by imposed temperature and concentration differences between two opposite vertical walls. These are chosen such that a pure conduction state exists. No-flux boundary conditions are imposed on the remaining four walls, with no-slip boundary conditions on all six walls. Numerical continuation is used to compute branches of spatially localized convection. Such states are referred to as convectons. Two branches of three-dimensional convectons with full symmetry bifurcate simultaneously from the conduction state and undergo homoclinic snaking. Secondary bifurcations on the primary snaking branches generate secondary snaking branches of convectons with reduced symmetry. The results are complemented with direct numerical simulations of the three-dimensional equations.
Dielectrophoretic force-driven thermal convection in annular geometry
Authors: Yoshikawa Harunori N. , Crumeyrolle Olivier , Mutabazi Innocent
Published: February 2013

The thermal convection driven by the dielectrophoretic force is investigated in annular geometry under microgravity conditions. A radial temperature gradient and a radial alternating electric field are imposed on a dielectric fluid that fills the gap of two concentric infinite-length cylinders. The resulting dielectric force is regarded as thermal buoyancy with a radial effective gravity. This electric gravity varies in space and may change its sign depending on the temperature gradient and the cylinder radius ratio. The linear stability problem is solved by a spectral-collocation method. The critical mode is stationary and non-axisymmetric. The critical Rayleigh number and wavenumbers depend sensitively on the electric gravity and the radius ratio. The mechanism behind the instability is examined from an energetic viewpoint. The instability in wide gap annuli is an exact analogue to the gravity-driven thermal instability.
A pepper-pot emittance meter for low-energy heavy-ion beams
Authors: Kremers H. R. , Beijers J. P. M. , Brandenburg S.
Published: February 2013

A novel emittance meter has been developed to measure the four-dimensional, transverse phase-space distribution of a low-energy ion beam using the pepper-pot technique. A characteristic feature of this instrument is that the pepper-pot plate, which has a linear array of holes in the vertical direction, is scanned horizontally through the ion beam. This has the advantage that the emittance can also be measured at locations along the beam line where the beam has a large horizontal divergence. A set of multi-channel plates, scintillation screen, and ccd camera is used as a position-sensitive ion detector allowing a large range of beam intensities that can be handled. This paper describes the design, construction, and operation of the instrument as well as the data analysis used to reconstruct the four-dimensional phase-space distribution of an ion beam. Measurements on a 15 keV He+ beam are used as an example.
Point defect reduction and carrier lifetime improvement of Si- and C-face 4H-SiC epilayers
Authors: Miyazawa Tetsuya , Tsuchida Hidekazu
Published: February 2013

The impact of two post-growth processes, namely, C+-implantation/annealing process and thermal oxidation/annealing process, on trap concentrations in thick n-type 4H-SiC epilayers was studied for both Si- and C-face. Conditions such as the implantation dose and annealing temperature of the C+-implantation/annealing processes were optimized for Si-face epilayers, and consequently the Z1/2 center was eliminated up to 100 μm or more, and the minority carrier lifetime reached 13 μs while maintaining a good surface morphology. The effect of the process conditions on the creation of new traps, including ON1 center, was also studied in both Si- and C-face epilayers. The ON1 center was introduced in both Si- and C-face by two post-growth processes, although the concentration was found to vary according to the polar face and the post-growth processes. The mechanism of the different impacts on Z1/2 center reduction and ON1 center creation by the two post-growth processes on Si- and C-face is discussed.
Investigation of thermal conductivity, viscosity, and electrical conductivity of graphene based nanofluids
Authors: Kole Madhusree , Dey T. K.
Published: February 2013

Stable and well dispersed functionalized graphene–ethylene glycol (EG) + distilled water nanofluids having graphene nano-sheets (GnS) volume concentration between 0.041 and 0.395 vol. % are prepared without any surfactant. Graphene nano-sheets are prepared from high purity graphite powder by Hummers method followed by exfoliation and reduction by hydrogen gas. Thus, obtained hydrogen exfoliated graphene (HEG) is then functionalized using acid. The graphene nano-sheets are characterized using XRD, TEM, Raman spectroscopy, and FTIR spectroscopy. Thermal conductivity and viscosity measurements are performed both as a function of graphene loading and temperature between 10 and 70 °C. Thermal conductivity enhancement of ∼15% for a loading of 0.395 vol. % f-HEG is observed at room temperature. The measured nanofluid's thermal conductivity is explained well in terms of the expression derived by Nan et al. (J. Appl. Phys. 81, 6692 (1997)), which considers matrix-additive interface contact resistance of mis-oriented ellipsoidal particles. The viscosity of the prepared f-HEG nanofluids and the base fluid (EG + distilled water) displays non-Newtonian behaviour with the appearance of shear thinning and nearly 100% enhancement compared to the base fluid (EG + DI water) with f-HEG loading of 0.395 vol. %. Known theoretical models for nanofluid's viscosity fail to explain the observed f-HEG volume concentration dependence of the nanofluid's viscosity. Temperature dependence of the studied nanofluid between 10 and 70 °C is explained well by the correlations proposed earlier for nanofluids with spherical nanoparticles. Electrical conductivity of the f-HEG nanofluids shows significant enhancement of ∼8620% for 0.395 vol. % loading of f-HEG in a base fluid of 70:30 mixture of EG and distilled water.
Charge deep-level transient spectroscopy of SiO2 and Al2O3 layers with embedded Ge nanocrystals
Authors: Antonova I. V. , Popov V. I. , Smagulova S. A. , Jedrzejewski J. , Balberg I.
Published: February 2013

The present study of deep level transient spectroscopy (DLTS) is focused on a comparison of the trap states in two types of Ge nanocrystallites (NCs)-insulator composites. The investigated systems were the dielectric matrices Al2O3 and SiO2 in which the Ge NCs were embedded. We have found couples of traps with related values of activation energies in both the Ge:Al2O3 and the Ge:SiO2 films. In the films with a relatively low Ge content (where only small NCs sized 3–5 nm could have been detected by means of Raman spectroscopy), we observed traps with an energy level ∼50 meV in the Ge:Al2O3 films and 120 and 50 meV in the Ge:SiO2 films. In both systems, we found that the electron traps have a small carrier capture cross-section (10−21–10−23 cm2). We have identified the levels of the traps to be the quantum confinement levels in the small Ge NCs. For samples of higher Ge contents, where the NC size reaches about 20 nm and where an appreciable portion of the dielectric matrix consists of amorphous Ge (α-Ge), we found traps with an energy of 0.22–0.24 eV in the Ge:Al2O3, and 0.26–0.27 eV in the Ge:SiO2 samples. We suggest that this peak in the charge DLTS (Q-DLTS) spectra is associated with a trap at the Ge-NC/α-Ge interface. We have also identified the energy position of a defect level in the Ge:Al2O3 layers, which lies 0.46–0.49 eV below the conduction-band edge of the Si substrate.
Unusual magnetic frustration in Lu-doped Gd5Ge4
Authors: Mudryk Y. , Pecharsky V. K. , Gschneidner K. A.
Published: February 2013

Magnetic properties of the (Gd0.975Lu0.025)5Ge4 alloy have been measured and compared with the parent Gd5Ge4 compound. Lu doping weakens the ferromagnetic interactions in Gd5Ge4 and this effect is much stronger than what may be expected from a simple dilution effect. An unusual magnetic frustration, likely induced by the kinetic arrest of the O(II) antiferromagnetic–O(I) ferromagnetic magnetostructural transformation as reported in the parent Gd5Ge4, has been observed.
Phase transition temperature and paramagnetic effect in Al1−xCrxK(SO4)2·12H2O (x = 0, 0.07, and 0.2) crystals studied by 27Al nuclear magnetic resonance relaxation time
Authors: Chang Celesta L. , Jeong Se-Young , Paik Younkee
Published: February 2013

The physical properties of Al1−xCrxK(SO4)2·12H2O (x = 0, 0.07, and 0.2) single crystals as a function of temperature were studied by observing their 27Al nuclear magnetic resonance spectra and relaxation times. The effects of partial replacement of Al3+ ions with paramagnetic Cr3+ ions were examined on the basis of the physical properties of pure AlK(SO4)2·12H2O crystals. The phase transition temperatures TC varied depending on the concentration of paramagnetic ions. In addition, the spin–lattice relaxation time T1 of crystals containing Cr3+ ions was shorter than that of crystals without paramagnetic ions. The paramagnetic effects on T1 and TC were strongest for 27Al in Al0.8Cr0.2 K(SO4)2·12H2O crystals with 0.2 mol. % of Cr3+ ions.
Microstructures and magnetostrictive strains of Fe-Ga-Ni ferromagnetic shape memory alloys
Authors: Lin Yin-Chih
Published: February 2013

Transmission electron microscopy (TEM), a magnetostrictive-meter setup, and a superconducting quantum interference device magnetometer were used to investigate the microstructures, saturation magnetostriction, and magnetic properties of bulk Fe81Ga19 and Fe73Ga19Ni8 (at. %) ferromagnetic shape memory alloys (FSMAs). In the Fe81Ga19 FSMA, after solution treatment (ST) at 1100 °C for 4 h and quenching in ice brine, the antiphase boundary segments of the D03 domain were observed in the A2 (disordered) matrix. When the Fe81Ga19 FSMA was solution treated and aged at 750 °C for 24 h and then furnace cooled (FC), the A2 + D03 phase transformed into A2 + B2 + D03 structures, accompanied by coarse B2 + D03 precipitates in the A2 matrix. This result decreased the saturation magnetostriction of the aged Fe81Ga19 FSMA. However, adding more Ni to the Fe81−xGa19Nix (x = 8 at. % Ni) FSMAs enhanced the formation of B2 + D03 structures, further decreased the saturation magnetostriction, and destroyed the ferromagnetic shape memory effect in Fe73Ga19Ni8 FSMA ST, aged at 750 °C for 24 h, and FC.
Electrostatics of two charged conducting ellipsoids
Authors: Murovec T. , Brosseau C.
Published: February 2013

Predictions of the electrostatic force (EF) for charged conducting spheres have been made previously using first-principles electrostatics [J. Lekner, Meas. Sci. Technol. 23, 085007 (2012)]. Here, finite element calculations of EF are presented for a variety of conducting ellipsoids differing with respect to size, gap distance, orientation, and shape. The results are expressed in terms of directly measurable experimental parameters. Our results are consistent with those of Lekner, namely, that charged ellipsoids exhibit mutual repulsion at all distances when they have the same charging potential, otherwise EF becomes attractive when the gap distance between the two ellipsoids is close enough. Additionally, we analyze the relationship between short-range attraction, capacitance, and EF in detail. The complexity of the electrostatic response on both external and material parameters suggests applications not only in electrostatics but in plasmonics and biosensor devices as well.
Wireless pad-free integrated circuit debugging by powering modulation and lock-in infrared sensing
Authors: León J. , Perpiñà X. , Vellvehi M. , Baldi A. , Sacristán J. , Jordà X.
Published: February 2013

In this work, non-functional radio frequency identification pad-free chips are analyzed by modulating its powering scheme and noninvasively sensing their surface infrared (IR) emission with an IR camera following lock-in strategies. This approach is justified by the chip wireless powering strategy and its pad-free design. As a result, latch-up triggering has been identified as the failure mechanism, also showing that electrical figures of merit can be extracted non-invasively (i.e., coils coupling frequency and its bandwidth).
Spin and orbital magnetization loops obtained using magnetic Compton scattering
Authors: Itou M. , Koizumi A. , Sakurai Y.
Published: February 2013

We present an application of magnetic Compton scattering (MCS) to decompose a total magnetization loop into spin and orbital magnetization contributions. A spin magnetization loop of SmAl2 was measured by recording the intensity of magnetic Compton scattering as a function of applied magnetic field. Comparing the spin magnetization loop with the total magnetization one measured by a vibrating sample magnetometer, the orbital magnetization loop was obtained. The data display an anti-coupled behavior between the spin and orbital magnetizations and confirm that the orbital part dominates the magnetization.
Ultrashort laser-driven stable-buckling of blisters in chirped mirror
Authors: Li Chen Shun , An Zhao Yuan , Da Shao Jian , Zhi Wang Yan , Fang Zhou , Feng Liu Xiao , Hang Hu Guo , Xin Leng Yu , Xu Yi
Published: February 2013

Multilayer dielectric mirrors (niobium pentoxide/silica) were irradiated by single 800 nm-38fs laser pulses. A circular blister feature appeared in the chirped mirrors at a wide range of laser fluence, while only existed above a few percent of the damage threshold for the high-reflector. Absorptive source of laser energy can be determined by combining theoretical simulation with focused ion beam technology. Mechanical analysis with a linear-elastic buckling model reveals the blister evolution belonging to a stable-buckling process until the blister radius confined by limited laser spot size.
Giant magnetoelectric effect in self-biased laminates under zero magnetic field
Authors: Li Menghui , Wang Zhiguang , Wang Yaojin , Li Jiefang , Viehland D.
Published: February 2013

A giant magnetoelectric (ME) effect in self-biased annealed Metglas/Pb(Zr,Ti)O3/Metglas laminates under zero magnetic bias is reported. The remanent magnetization was increased by annealing Metglas, which generated an internal bias field. This shifted the M-H hysteresis loops, yielding large values for the ME voltage coefficient of αME = 12 V/cm·Oe and 380 V/cm·Oe at 1 kHz and electromechanical resonance under zero magnetic bias, respectively. This self-biased laminate is shown to have a high sensitivity to ac magnetic fields.
Fabrication and transport properties of Sr0.6K0.4Fe2As2 multifilamentary superconducting wires
Authors: Yao Chao , Ma Yanwei , Zhang Xianping , Wang Dongliang , Wang Chunlei , Lin He , Zhang Qianjun
Published: February 2013

Seven-core Ag/Fe sheathed Sr0.6K0.4Fe2As2 (Sr-122) superconducting wires were produced by the ex situ powder-in-tube method. The relationship between the cold-work deformation process and the superconducting properties of the wires was systematically studied. It was found that flat rolling can efficiently increase the mass density of the superconducting core, thus, significantly improving the transport critical current density (Jc) of the as-drawn wires. The transport Jc of the best sample achieved 21.1 kA/cm2 at 4.2 K in self field, and showed very weak magnetic field dependence at high fields. Our result suggested a promising future of multifilamentary iron-based superconductors in practical applications.
Investigation of the charge transport mechanism and subgap density of states in p-type Cu2O thin-film transistors
Authors: Jeong Chan-Yong , Sohn Joonsung , Song Sang-Hun , Cho In-Tak , Lee Jong-Ho , Cho Eou-Sik , Kwon Hyuck-In
Published: February 2013

We investigate the charge transport mechanism and subgap density of states (DOS) in p-type Cu2O thin-film transistors (TFTs) using the bias and temperature dependence of the drain currents. Among several charge transport mechanisms, the experimental data are well matched with a multiple trapping and release model, which suggests that the charge transport in the Cu2O TFT is mainly limited by trap states at grain boundaries or dielectric/semiconductor interface. The subgap DOS is extracted based on the Meyer-Neldel rule. Large density of subgap states is extracted, which is considered to be the reason of low mobility in fabricated Cu2O TFTs.
Autonomous regulation of the insect gut by circadian genes acting downstream of juvenile hormone signaling
Authors: Bajgar Adam , Jindra Marek , Dolezel David
Published: February 2013

In temperate regions, the shortening day length informs many insect species to prepare for winter by inducing diapause. The adult diapause of the linden bug,
Pyrrhocoris apterus
, involves a reproductive arrest accompanied by energy storage, reduction of metabolic needs, and preparation to withstand low temperatures. By contrast, nondiapause animals direct nutrient energy to muscle activity and reproduction. The photoperiod-dependent switch from diapause to reproduction is systemically transmitted throughout the organism by juvenile hormone (JH). Here, we show that, at the organ-autonomous level of the insect gut, the decision between reproduction and diapause relies on an interaction between JH signaling and circadian clock genes acting independently of the daily cycle. The JH receptor Methoprene-tolerant and the circadian proteins Clock and Cycle are all required in the gut to activate the
Par domain protein 1
gene during reproduction and to simultaneously suppress a mammalian-type
cryptochrome 2
gene that promotes the diapause program. A nonperiodic, organ-autonomous feedback between Par domain protein 1 and Cryptochrome 2 then orchestrates expression of downstream genes that mark the diapause vs. reproductive states of the gut. These results show that hormonal signaling through Methoprene-tolerant and circadian proteins controls gut-specific gene activity that is independent of circadian oscillations but differs between reproductive and diapausing animals.
Constructing national history in political discourse: Coherence and contradiction (Moldova, 2001-2009)
Authors: Iglesias Julien Danero
Published: February 2013

History is one of the many instruments available for the persuasive construction of a nation. In Moldova, the Party of the Communists of the Republic of Moldova (PCRM), in office from 2001 to 2009, advocated for a Soviet-based version of the Moldovan nation. This “Moldovanism” boasted of the existence of a “Moldovan People” and was relied upon to justify the independence of the former Romanian province. Vladimir Voronin, the party's leader and president of the Republic during this period, promoted this “civic” Moldovan nation and created what seemed to be a coherent and ad hoc construction of an independent Moldovan nation.

This paper focuses on communist political discourse during this eight year period. Through the use of Critical Discourse Analysis, this paper focuses on the discursive construction of the Moldovan nation. It is based on Voronin's official speeches and messages from key occasions such as Independence Day and Victory Day.

This paper demonstrates the varied use of history in these speeches which improves understanding of the process of the construction of a nation. Moreover, it demonstrates that this construction, far from being coherent, was also sometimes contradictory. Indeed, discourse was adapted to the immediate context and audience. Finally, the paper explains how an explicitly “civic” discourse can be implicitly and, sometimes even explicitly, “ethnic” and “exclusive”.
Weighted local Orlicz-Hardy spaces on domains and their applications in inhomogeneous Dirichlet and Neumann problems
Authors: Cao Jun , Chang Der-Chen , Yang Dachun , Yang Sibei
Published: February 2013

Let

Ω
\Omega

be either

R

n

\mathbb {R}^n

or a strongly Lipschitz domain of

R

n

\mathbb {R}^n

, and

ω
∈

A

∞

(

R

n

)

\omega \in A_{\infty }(\mathbb {R}^n)

(the class of Muckenhoupt weights). Let

L
L

be a second-order divergence form elliptic operator on

L
2

(
Ω
)

L^2 (\Omega )

with the Dirichlet or Neumann boundary condition, and assume that the heat semigroup generated by

L
L

has the Gaussian property

(

G
1

)

(G_1)

with the regularity of their kernels measured by

μ
∈
(
0
,
1
]

\mu \in (0,1]

. Let

Φ
\Phi

be a continuous, strictly increasing, subadditive, positive and concave function on

(
0
,
∞
)

(0,\infty )

of critical lower type index

p

Φ

−

∈
(
0
,
1
]

p_{\Phi }^-\in (0,1]

. In this paper, the authors first introduce the “geometrical” weighted local Orlicz-Hardy spaces

h

ω
,

r

Φ

(
Ω
)

h^{\Phi }_{\omega ,\,r}(\Omega )

and

h

ω
,

z

Φ

(
Ω
)

h^{\Phi }_{\omega ,\,z}(\Omega )

via the weighted local Orlicz-Hardy spaces

h

ω

Φ

(

R

n

)

h^{\Phi }_{\omega }(\mathbb {R}^n)

, and obtain their two equivalent characterizations in terms of the nontangential maximal function and the Lusin area function associated with the heat semigroup generated by

L
L

when

p

Φ

−

∈
(
n

/

(
n
+
μ
)
,
1
]

p_{\Phi }^-\in (n/(n+\mu ),1]

. Second, the authors furthermore establish three equivalent characterizations of

h

ω
,

r

Φ

(
Ω
)

h^{\Phi }_{\omega ,\,r}(\Omega )

in terms of the grand maximal function, the radial maximal function and the atomic decomposition when the complement of

Ω
\Omega

is unbounded and

p

Φ

−

∈
(
0
,
1
]

p_{\Phi }^-\in (0,1]

. Third, as applications, the authors prove that the operators

∇
2

G

D

\nabla ^2{\mathbb G}_D

are bounded from

h

ω
,

r

Φ

(
Ω
)

h^{\Phi }_{\omega ,\,r}(\Omega )

to the weighted Orlicz space

L

ω

Φ

(
Ω
)

L^{\Phi }_{\omega }(\Omega )

, and from

h

ω
,

r

Φ

(
Ω
)

h^{\Phi }_{\omega ,\,r}(\Omega )

to itself when

Ω
\Omega

is a bounded semiconvex domain in

R

n

\mathbb {R}^n

and

p

Φ

−

∈
(

n

n
+
1

,
1
]

p_{\Phi }^-\in (\frac {n}{n+1},1]

, and the operators

∇
2

G

N

\nabla ^2{\mathbb G}_N

are bounded from

h

ω
,

z

Φ

(
Ω
)

h^{\Phi }_{\omega ,\,z}(\Omega )

to

L

ω

Φ

(
Ω
)

L^{\Phi }_{\omega }(\Omega )

, and from

h

ω
,

z

Φ

(
Ω
)

h^{\Phi }_{\omega ,\,z}(\Omega )

to

h

ω
,

r

Φ

(
Ω
)

h^{\Phi }_{\omega ,\,r}(\Omega )

when

Ω
\Omega

is a bounded convex domain in

R

n

\mathbb {R}^n

and

p

Φ

−

∈
(

n

n
+
1

,
1
]

p_{\Phi }^-\in (\frac {n}{n+1},1]

, where

G

D

{\mathbb G}_D

and

G

N

{\mathbb G}_N

denote, respectively, the Dirichlet Green operator and the Neumann Green operator.
DELAYED RECURRENT NEOVASCULARIZATION AND PERSISTENT AVASCULAR RETINA FOLLOWING INTRAVITREAL BEVACIZUMAB FOR RETINOPATHY OF PREMATURITY
Authors: Mehta Sonia , Hubbard G. Baker
Published: February 2013

Purpose:

Intravitreal bevacizumab is becoming increasingly popular in the treatment of retinopathy of prematurity. Ophthalmologists should be aware of potential complications and failures of this treatment.

Methods:

Case report and literature review.

Results:

A premature infant born at 23 weeks gestational age developed zone 1 stage 3 retinopathy of prematurity with plus disease in both eyes. At 36 weeks postmenstrual age, the patient was treated with intravitreal bevacizumab and the neovascularization initially regressed. However, the patient's peripheral avascular retina persisted and at 53 weeks postmenstrual age, the patient developed recurrent neovascularization and plus disease of both eyes requiring treatment with laser photocoagulation. The infant showed regression of neovascularization and improvement of plus disease after laser, but contraction of fibroglial tissue caused a tractional retinal detachment. The retina was successfully reattached after pars plana vitrectomy and membrane peel.

Conclusion:

Infants receiving intravitreal bevacizumab as primary treatment for retinopathy of prematurity can show initial regression of neovascularization with delayed recurrence of neovascularization and persistence of peripheral avascular retina greater than 4 months after initial treatment. Ophthalmologists following infants with retinopathy of prematurity treated with intravitreal bevacizumab should be aware of the possibility of delayed recurrent neovascularization and subsequent complications.
Migration confers survival benefits against avian predators for partially migratory freshwater fish
Authors: Skov Christian , Chapman Ben B. , Baktoft Henrik , Brodersen Jakob , Brönmark Christer , Hansson Lars-Anders , Hulthén Kaj , Nilsson P. Anders
Published: February 2013

The importance of predation risk in shaping patterns of animal migration is not well studied, mostly owing to difficulties in accurately quantifying predation risk for migratory versus resident individuals. Here, we present data from an extensive field study, which shows that migration in a freshwater fish (roach,Rutilus rutilus) that commonly migrates from lakes to streams during winter confers a significant survival benefit with respect to bird (cormorant,Phalacrocorax carbospp.) predation. We tagged over 2000 individual fish in two Scandinavian lakes over 4 years and monitored migratory behaviour using passive telemetry. Next, we calculated the predation vulnerability of fish with differing migration strategies, by recovering data from passive integrated transponder tags of fish eaten by cormorants at communal roosts close to the lakes. We show that fish can reduce their predation risk from cormorants by migrating into streams, and that probability of being preyed upon by cormorants is positively related to the time individuals spend in the lake during winter. Our data add to the growing body of evidence that highlights the importance of predation for migratory dynamics, and, to our knowledge, is one of the first studies to directly quantify a predator avoidance benefit to migrants in the field.
Exposure to sperm competition risk improves survival of virgin males
Authors: Moatt Joshua P. , Dytham Calvin , Thom Michael D. F.
Published: February 2013

Sperm competition between the ejaculates of multiple males for the fertilization of a given set of ova is taxonomically widespread. Males have evolved remarkable adaptations to increase their reproductive success under postcopulatory sexual selection, which in many species includes the ability to modify behaviour and ejaculate characteristics plastically to match the perceived level of sperm competition. Males of the model species
Drosophila melanogaster
increase mating duration and modify seminal fluid composition in response to short-term changes in sperm competition risk. If these responses increase a male's total investment in reproduction, he must either trade-off this cost against other life-history traits or suffer reduced survival. We tested whether mounting a plastic sperm competition response bears an instantaneous survival cost, and instead found that male
D. melanogaster
exposed to a high risk of sperm competition survive 12 per cent longer than those at low risk, equating to a 49 per cent reduction in the hourly hazard of death. This striking effect was found only among virgins: the high cost of mating in this species eliminates any such benefit among non-virgin males. Our results suggest that the improvement in survival found among virgins may be a product of males’ tactical responses to sperm competition.
Butterfly survival on an isolated island by improved grip
Authors: Duplouy Anne , Hanski Ilkka
Published: February 2013

On small isolated islands, natural selection is expected to reduce the dispersal capacity of organisms, as short distances do not require a high rate of dispersal, which might lead to accidental emigration from the population. In addition, individuals foregoing the high cost of maintaining flight capacity may instead allocate resources to other functions. However, in butterflies and many other insects, flight is necessary not only for dispersal but also for most other activities. A weakly flying individual would probably do worse and have an elevated rather than reduced probability of accidental emigration. Here, we report results consistent with the hypothesis that a butterfly population on an isolated island, instead of having lost its flight capacity, has evolved better grip to resist the force of wind and to avoid being blown off the island. Our study suggests that local adaptation has occurred in this population in spite of its very small size (Ne∼ 100), complete isolation, low genetic variation and high genetic load.
A dynamic history of gene duplications and losses characterizes the evolution of the SPARC family in eumetazoans
Authors: Bertrand Stephanie , Fuentealba Jaime , Aze Antoine , Hudson Clare , Yasuo Hitoyoshi , Torrejon Marcela , Escriva Hector , Marcellini Sylvain
Published: February 2013

The vertebrates share the ability to produce a skeleton made of mineralized extracellular matrix. However, our understanding of the molecular changes that accompanied their emergence remains scarce. Here, we describe the evolutionary history of the SPARC (secreted protein acidic and rich in cysteine) family, because its vertebrate orthologues are expressed in cartilage, bones and teeth where they have been proposed to bind calcium and act as extracellular collagen chaperones, and because further duplications of specific SPARC members produced the small calcium-binding phosphoproteins (SCPP) family that is crucial for skeletal mineralization to occur. Both phylogeny and synteny conservation analyses reveal that, in the eumetazoan ancestor, a unique ancestral gene duplicated to give rise toSPARCandSPARCBdescribed here for the first time. Independent losses have eliminated one of the two paralogues in cnidarians, protostomes and tetrapods. Hence, only non-tetrapod deuterostomes have conserved both genes. Remarkably,SPARCandSPARCBparalogues are still linked in the amphioxus genome. To shed light on the evolution of the SPARC family members in chordates, we performed a comprehensive analysis of their embryonic expression patterns in amphioxus, tunicates, teleosts, amphibians and mammals. Our results show that in the chordate lineage SPARC and SPARCB family members were recurrently recruited in a variety of unrelated tissues expressing collagen genes. We propose that one of the earliest steps of skeletal evolution involved the co-expression of SPARC paralogues with collagenous proteins.
Inbreeding in horsenettle (Solanum carolinense) alters night-time volatile emissions that guide oviposition byManduca sextamoths
Authors: Kariyat Rupesh R. , Mauck Kerry E. , Balogh Christopher M. , Stephenson Andrew G. , Mescher Mark C. , De Moraes Consuelo M.
Published: February 2013

Plant volatiles serve as key foraging and oviposition cues for insect herbivores as well as their natural enemies, but little is known about how genetic variation within plant populations influences volatile-mediated interactions among plants and insects. Here, we explore how inbred and outbred plants from three maternal families of the native weed horsenettle (Solanum carolinense) vary in the emission of volatile organic compounds during the dark phase of the photoperiod, and the effects of this variation on the oviposition preferences ofManduca sextamoths, whose larvae are specialist herbivores of Solanaceae. Compared with inbred plants, outbred plants consistently released more total volatiles at night and more individual compounds—including some previously reported to repel moths and attract predators. Female moths overwhelmingly chose to lay eggs on inbred (versus outbred) plants, and this preference persisted when olfactory cues were presented in the absence of visual and contact cues. These results are consistent with our previous findings that inbred plants recruit more herbivores and suffer greater herbivory under field conditions. Furthermore, they suggest that constitutive volatiles released during the dark portion of the photoperiod can convey accurate information about plant defence status (and/or other aspects of host plant quality) to foraging herbivores.
Structural basis for dual roles of Aar2p in U5 snRNP assembly
Authors: Weber Gert , Cristão Vanessa F. , Santos Karine F. , Jovin Sina Mozaffari , Heroven Anna C. , Holton Nicole , Lührmann Reinhard , Beggs Jean D. , Wahl Markus C.
Published: February 2013

Yeast U5 small nuclear ribonucleoprotein particle (snRNP) is assembled via a cytoplasmic precursor that contains the U5-specific Prp8 protein but lacks the U5-specific Brr2 helicase. Instead, pre-U5 snRNP includes the Aar2 protein not found in mature U5 snRNP or spliceosomes. Aar2p and Brr2p bind competitively to a C-terminal region of Prp8p that comprises consecutive RNase H-like and Jab1/MPN-like domains. To elucidate the molecular basis for this competition, we determined the crystal structure of Aar2p in complex with the Prp8p RNase H and Jab1/MPN domains. Aar2p binds on one side of the RNase H domain and extends its C terminus to the other side, where the Jab1/MPN domain is docked onto a composite Aar2p–RNase H platform. Known Brr2p interaction sites of the Jab1/MPN domain remain available, suggesting that Aar2p-mediated compaction of the Prp8p domains sterically interferes with Brr2p binding. Moreover, Aar2p occupies known RNA-binding sites of the RNase H domain, and Aar2p interferes with binding of U4/U6 di-snRNA to the Prp8p C-terminal region. Structural and functional analyses of phospho-mimetic mutations reveal how phosphorylation reduces affinity of Aar2p for Prp8p and allows Brr2p and U4/U6 binding. Our results show how Aar2p regulates both protein and RNA binding to Prp8p during U5 snRNP assembly.
Corporate sustainability performance and firm performance research
Authors: Goyal Praveen , Rahman Zillur , Kazmi A.A.
Published: February 2013

Purpose

The aim of this paper is to present a taxonomy of available literature on the relation of sustainability performance and firm performance, and to provide a path for future research for this field of study.

Design/methodology/approach

Research papers were collected on sustainability performance assessment from various journals available at different online databases. The unit of evaluation was a full paper published in one of the relevant journals. Papers were classified in different categories and tabulated under various classes. A total of 101 research paper sources were studied and assessed in terms of nature of research, level of analysis, and application.

Findings

The review reveals that most of the research in the field of sustainability performance and firm performance association, analyzed this relationship in developed countries. The result differs in various cultural and economic contexts and there is no universally accepted direction of this relationship. Contribution of research has also revealed a pattern of growth in recent years. Financial performance is used in most of the research as a proxy to firm performance. As discussed, the different research gaps may be exploited for further research. It also argues that further empirical research in relation of corporate sustainability performance and firm performance is required in developing countries.

Research limitations/implications

The findings of this paper can be generalized only to the specific population of online databases selected for this research for a given period of time and not for the entire universe of the sustainability performance literature. There may be various unexploited areas for future research in terms of different variables.

Originality/value

This paper fulfils the need of a comprehensive review of corporate sustainability performance assessment literature. It provides a literature review and bibliography for the period between January 1992 and March 2011 for the use of both academicians and practitioners.
Having a strategy for new service development – does it really matter?
Authors: Edvardsson Bo , Meiren Thomas , Schäfer Adrienne , Witell Lars
Published: February 2013

Purpose

The aim of this study is to investigate the role of key strategic factors in new service development (NSD). In particular, the role of service development strategy, a formalised development process, integrated development teams and customer co‐creation were investigated and the results were compared with managers' beliefs.

Design/methodology/approach

The study used a sample of more than 500 service development projects to test a NSD conceptual model. Regression analysis was used to test the relative importance of the key strategic factors, and the results were compared with managers' beliefs.

Findings

The results show that managers believe that customer co‐creation is most important in order to succeed with NSD. However, contrary to management belief, a service development strategy is the “missing link” in improving NSD performance. In addition, the research highlighted an interaction effect between integrated development teams and customer co‐creation, which means that project managers should focus on individual competencies on the development team and how they interact with customers throughout the NSD process.

Originality/value

For a long time, NSD has failed to receive the attention it deserves, not just in practice but also in service research. This study shows that the number of new services put on the market and then withdrawn because of low sales remains as high as 43 per cent. This paper contributes knowledge on how to reduce the number of failures in NSD by pointing out the key strategic factors that influence NSD performance.
Royal accommodations: pilgrim rest houses in early colonial South India
Authors: Linderman Michael C.
Published: February 2013

Purpose

This article provides background on the historical development of royal hospitality in India before the advent of commercial hospitality in the twentieth century. The aim of the paper is to insert into the historiography of commercial hospitality the ancient Indian practice of endowing pilgrim rest houses, or chattrams (choultry) for the temporary housing and feeding of travelers, religious mendicants, and other groups in Indian society. As a case study, the article focuses on the chattrams of the Maratha Kings of Tanjavur (Tanjore) in South India, especially during the reign of Raja Serfoji II (r. 1798‐1832). Serfoji, working from the palette of past practices of his forebears, expanded these practices of traditional Hindu religious hospitality to include more progressive and inclusive charity, education and hospitality during the late eighteenth and early nineteenth centuries. Serfoji's munificent activities in his chattrams pose a challenge to any characterization that royal elites adapted historically dormant or static institutions to practical usage in the twentieth century.

Design/methodology/approach

This article is based on archival research into the role of institution building in strategies of indigenous kingship in early colonial India. The primary methodology used is content and descriptive analyses of archival documents in the Tamil language related to chattrams constructed by the Maratha court of Tanjavur between 1739 and 1855 CE.

Findings

The archival data show that the Maratha court of Tanjavur, particularly under Raja Serfoji II (r. 1798‐1832), incorporated through the chattram institution a greater variety of social groups in its charitable mandate by expanding the traditional forms of pious and ceremonial hospitality of the court to include not only religious mendicants and pilgrims, but also students, staff and European guests as well. The article reveals the manner in which such practices could sustain aspects of the traditional relationship between ruler and subject while creating newly responsive forms of social outreach to wider constituencies by an indigenous court that had been reduced to titular status under the rise of the British East India Company after 1798.

Originality/value

As yet, there has been no systematic survey of the evolution of commercial hospitality in India, nor particularly one that includes the practice of charitable rest houses in pre‐modern India. This article focuses attention on the diversified social functions of these institutions in the early colonial period in south India, and introduces these institutions as a potential precedent of later forms of commercial hospitality.
Challenges of international technology collaboration with Russian R&D organisations
Authors: Trifilova Anna , Bartlett Dean , Altman Yochanan
Published: February 2013

Purpose

This paper aims to examine the challenges experienced by Russian research and development (R&D) organisations in international technology collaboration in the global innovation arena.

Design/methodology/approach

A total of 33 Russian R&D organisations were selected from a sample of 138 potential participating organisations from the Central, Nord‐Western and Volga Federal Districts of Russia to take part in a qualitative interview study. Organisations were selected based on their responses to a questionnaire which measured the extent and nature of their experience in international technology collaborations. Participants were interviewed about their experiences of engaging in international technology collaboration under two different modes of collaboration: short term customer‐supplier relationships vs longer‐term strategic alliances. The semi‐structured interviews focused on 15 different issues which had been derived from the previously published literature on international technology collaboration and a thematic analysis was conducted on the resultant data.

Findings

The analysis indicates which of the issues reported as problematic in the literature were pertinent to the Russian organisations in the sample under each mode of collaboration. The findings also provide some evidence that Russian R&D organisations have made progress in the transition from the command to the market economy and are adjusting to the new environment, albeit gradually in some cases.

Research limitations/implications

The paper presents interpretive, qualitative findings, which were analysed from a Russian perspective in three out of seven Federal Districts of Russia. The research sample does not include non‐Russian counterparts and the analysis is restricted to those variables which have previously been identified as exerting an influence over international technology collaborations.

Practical implications

The study reveals a broad range of insights into the types of issues which warrant close managerial attention from both Russian managers and their international partners in engaging in international technology collaborations with contemporary Russian R&D organisations.

Originality/value

The research suggests that different sets of challenges emerge for organisations engaged in different modes of international collaboration and provides insight into the unique context of Russia, challenging some of the previously published analyses of the influence of Russian business and managerial practices on the innovativeness of contemporary Russian organisations.