bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydrodynamic forces involving deformable interfaces at nanometer separations
Authors: Manica Rogério , Connor Jason N. , Dagastine Raymond R. , Carnie Steven L. , Horn Roger G. , Chan Derek Y. C.
Published: March 2008

A model is developed to describe the dynamic forces acting between two deformable drops, or between one drop and a solid surface, when they are in relative axisymmetric motion at separations of ≲100nm in a Newtonian liquid. Forces arise from hydrodynamic pressure in the draining liquid film that separates the interfaces and from disjoining pressure due to repulsive or attractive surface forces. Predictions of the model are successfully compared with recent experimental measurements of the force between two micrometer-scale surfactant stabilized decane drops in water in an atomic force microscope [S. L. Carnie, D. Y. C. Chan, C. Lewis, R. Manica, and R. R. Dagastine, Langmuir 21, 2912 (2005); R. R. Dagastine, R. Manica, S. L. Carnie, D. Y. C. Chan, G. W. Stevens, and F. Grieser, Science 313, 210 (2006)] and with subnanometer resolution measurements of time-dependent deformations of a millimeter-scale mercury drop approaching a flat mica surface in a modified surface force apparatus [J. N. Connor and R. G. Horn, Faraday Discuss. 123, 193 (2003); R. G. Horn, M. Asadullah, and J. N. Connor, Langmuir 22, 2610 (2006)]. Special limits of the model applicable to small and moderate deformation regimes are also studied to elucidate the key physical ingredients that contribute to the characteristic behavior of dynamic collisions involving fluid interfaces.
Reduction of adjacent track encroachment in exchange coupled composite media through soft magnetic layer with high Ku
Authors: Hong Sooyoul , Che Xiaodong , Tang Yuhui , Zhu Jian-Gang
Published: March 2008

Exchange coupled composite (ECC) media on the Al disk substrate with soft underlayer were fabricated with different anisotropy field ratios between hard magnetic and soft magnetic layers. The enhanced signal to noise ratio of about 2.5dB was obtained from ECC media having anisotropy field ratio of 3, which showed even narrow magnetic write width, compared to ECC media with anisotropy field ratio of over 10. Especially, ECC media with lower anisotropy field ratio of 3 exhibited much reduction in adjacent track encroachment (ATE). Micromagnetic modeling indicated that large negative nucleation field is crucial to the implementation of ECC media with lower dc noise and improved ATE. The main reason is, for soft magnetic layer with high saturation magnetization and low anisotropy field, the very wide write bubble occurring during dynamic recording process. It resulted in poor ATE performance, which agreed well with experimental data.
Calibration of liquid crystal ultrafast pulse shaper with common-path spectral interferometry and application to coherent control with a covariance matrix adaptation evolutionary strategy
Authors: Wilson Jesse W. , Schlup Philip , Lunacek Monte , Whitley Darrell , Bartels Randy A.
Published: March 2008

An ultrafast pulse shaper for coherent control applications is described, complete with a simple, reliable calibration technique and an advanced learning control algorithm. The calibration technique makes use of a common-path interferometer, producing less noisy measurements than a conventional Mach–Zehnder interferometer. A covariance matrix adaptation evolutionary strategy (ES) is demonstrated to perform better than a traditional ES for high-dimensional search landscapes.
Single mode photonic quantum ring laser fabricated in hyperboloid drum shape
Authors: Yoon Junho , An Sung-Jae , Kwon O’Dae , Ku Ja Kang
Published: March 2008

From three dimensional whispering gallery cavities of GaAs photonic quantum ring fabricated in hyperboloid drum shape by chemically assisted ion beam etching with the central active region diameter of 0.9μm, we have observed single mode lasing near 838nm with a record low injection threshold of 300nA (Jth=47.1A∕cm2) in continuous wave operation at room temperature. This indicates that the quantum ring lasing phenomena associated with the three dimensional whispering gallery modes continue to persist, even at the submicron range overcoming the conventional two dimensional whispering gallery mode limit.
Magnetocaloric effect in R2Ti3Ge4 (R=Gd, Tb, and Er) compounds
Authors: Nirmala R. , Kundaliya Darshan C. , Morozkin A. V. , Malik S. K.
Published: March 2008

The heat capacity of polycrystalline R2Ti3Ge4 (R=Gd, Tb, and Er) compounds (orthorhombic, Sm5Ge4-type, space group Pnma) has been studied in the temperature range of 1.8–300K in various applied magnetic fields. The compounds with magnetic lanthanide elements show interesting low field magnetism intrigued by the possible presence of competing antiferromagnetic and ferromagnetic interactions. The magnetocaloric effect in these compounds is estimated from the field dependent heat capacity data. The magnetic entropy change and the adiabatic temperature change in the vicinity of the magnetic transition are found to be significant.
Characteristics of low energy atom and molecule beams generated by the charge exchange reaction
Authors: Hara Yasuhiro , Takashima Seigo , Yamakawa Koji , Den Shoji , Toyoda Hirotaka , Sekine Makoto , Hori Masaru
Published: March 2008

A low energy NB source, which consisted of a surface wave plasma (SWP) source and two large diameter carbon electrodes, was developed for damageless etching of ultralarge-scale integrated devices. Ion beams were extracted from the SWP using two carbon electrodes, accelerated and injected to the process chamber, and then neutralized without energy loss by a charge exchange reaction. The energy distribution functions of an Ar ion beam and an Ar atom beam was observed using a quadrupole mass spectroscope equipped with an energy analyzer. The energy of the Ar ion beam and the Ar atom beam was controlled by the acceleration voltage. N2 ion and N ion beams were also extracted from a nitrogen plasma source. The intensity ratio of the N ion beam to the N2 ion beam was 5:9, indicating that N ions were efficiently generated in the nitrogen SWP. The N2 ion and N ion beams were changed to N2 molecule and N atom beams, respectively, through a charge exchange reaction without energy loss. The energy of these beams was controlled by the acceleration voltage and was in the region less of than 100eV. When the acceleration voltage is higher than 40V, not only the primary peaks due to the N2 ion beam or N ion beam were observed but also a low energy second peak was observed in the energy distribution. The energy of the low energy second peak was controlled by the acceleration voltage. It was concluded that the low energy second peak corresponds to the N2 molecule ion beam and the N ion beam, which is extracted from the second plasma generated in the space between the two carbon electrodes.
Kinetics of creation and of thermal annealing of light-induced defects in microcrystalline silicon solar cells
Authors: Meillaud F. , Vallat-Sauvain E. , Shah Arvind , Ballif C.
Published: March 2008

Single-junction microcrystalline silicon (μc-Si:H) solar cells of selected i-layer crystalline volume fractions were light soaked (AM1.5, 1000h at 50°C) and subsequently annealed at increasing temperatures. The variations of subbandgap absorption during light soaking and during thermal annealing were monitored by Fourier transform photocurrent spectroscopy. The kinetics were shown to follow stretched exponential functions over long times such as 1000h. The effective time constants appearing in the stretched exponential function decrease with decreasing crystalline volume fraction as well with increasing annealing temperature. Their Arrhenius-like dependence on temperature is characterized by a unique value of the activation energy. Furthermore, we demonstrate that the configuration of the solar cells (p-i-n or n-i-p) does not influence the degradation kinetics, as long as the average crystallinity of the intrinsic layer is of comparable value.
Deposition of carbon-free silicon dioxide from pure hexamethyldisiloxane using an atmospheric microplasma jet
Authors: Raballand V. , Benedikt J. , von Keudell A.
Published: March 2008

Carbon-free silicon dioxide has been deposited at room temperature by injection of pure hexamethyldisiloxane (HMDSO) into an atmospheric pressure microplasma jet from argon. At low HMDSO flow rates [<0.1SCCM (SCCM denotes cubic centimeter per minute at STP)], the SiOxHz films contain no carbon and exhibit an oxygen to silicon ratio close to 2 according to x-ray photoelectron spectroscopy. At high HMDSO flow rates (>0.1SCCM), SiOxCyHz films with a carbon content of up to 21% are obtained. The transition between organic to inorganic film is confirmed by Fourier transformed infrared spectroscopy. The deposition of inorganic films without oxygen admixture is explained by an ion-induced polymerization scheme of HMDSO.
IV-VI diluted magnetic semiconductor Ge1−xMnxTe epilayer grown by molecular beam epitaxy
Authors: Fukuma Y. , Goto K. , Senba S. , Miyawaki S. , Asada H. , Koyanagi T. , Sato H.
Published: March 2008

Growth of the IV-VI diluted magnetic semiconductor Ge1−xMnxTe by molecular beam epitaxy is reported. The epitaxial growth of Ge1−xMnxTe (x=0.13) on BaF2 (111) with a GeTe buffer layer is confirmed by x-ray diffraction and reflection high-energy electron diffraction. The ferromagnetic order is clearly established by the magnetization and magnetotransport measurements. The Curie temperature of 100K is obtained for the hole concentration of 7.86×1020cm−3. The existence of the strong p-d exchange which gives rise to the ferromagnetic order is revealed by the hard x-ray photoemission measurements.
Full six-dimensional nonadiabatic quantum dynamics calculation for the energy pooling reaction O2(aΔ1)+O2(aΔ1)→O2(bΣ1)+O2(XΣ3)
Authors: Zhang Pei-Yu , Lu Rui-Feng , Zhang Ai-Jie , Chu Tian-Shu , Han Ke-Li
Published: March 2008

Six new potential energy surfaces of four singlet states and two triplet states for the title oxygen molecule reaction along with the spin-orbit coupling among them have been constructed from the complete active space second-order perturbation theory with a 6-311+G(d) basis. Accurate integral cross sections are calculated with a full six-dimensional nonadiabatic time-dependent quantum wave packet method. The thermal rate constant based on the integral cross sections agrees well with the result of the experimental measurements, and the intersystem crossing effects are also discussed in this electronic energy-transfer process.
Density characterization of femtosecond laser modification in polymers
Authors: Mochizuki Hiroyuki , Watanabe Wataru , Ezoe Rikuya , Tamaki Takayuki , Ozeki Yasuyuki , Itoh Kazuyoshi , Kasuya Makoto , Matsuda Katsumi , Hirono Satoshi
Published: March 2008

Bragg-type gratings were prepared by femtosecond laser irradiation in a series of optical polymers. The diffraction efficiency of polymethylpentene (PMP) was an order of magnitude higher than those of other polymers. Repeated scanning irradiation with femtosecond laser light formed gratings by refractive index changes inside the polymers. In PMP, whose density was the lowest among the polymers examined, large volume contraction by femtosecond laser irradiation was observed by transmission electron microscopy. The larger refractive index change of PMP was attributed to its large volume contraction based on its low density.
Upconversion electroluminescence in InAs quantum dot light-emitting diodes
Authors: Baumgartner A. , Chaggar A. , Patanè A. , Eaves L. , Henini M.
Published: March 2008

We investigate the low-temperature upconversion electroluminescence (UCEL) in GaAs p-i-n diodes with a layer of self-assembled InAs quantum dots (QDs) in the intrinsic region (i). Injection of carriers into the QD states at an applied bias well below the flatband condition results in near-band-edge GaAs electroluminescence, i.e., emission of photons with energies much larger than that supplied by the applied voltage and the thermal energy. We attribute the UCEL to an Auger-like recombination process and discuss its influence on carrier thermalization processes and the effect of an applied magnetic field.
Quantitative scanning capacitance microscopy on single subsurface InAs quantum dots
Authors: Smoliner J. , Brezna W. , Klang P. , Andrews A. M. , Strasser G.
Published: March 2008

Quantitative scanning capacitance microscopy on InAs quantum dots requires low modulation frequencies and complete darkness. Using a modified feedback method on our atomic force microscope, which allows to switch off the laser temporarily while the feedback loop keeps running, images of buried InAs self assembled quantum dots were acquired. The dots are clearly visible as bright areas in a contrast-rich capacitance landscape, which we attribute to thickness variations of the InAs wetting layer. Even at room temperature, spectroscopic data recorded at on-dot and off-dot positions exhibit a completely different behavior and show evidence of quantized states inside the dots.
Large lattice strain in individual grains of deformed nanocrystalline Ni
Authors: Shan Zhiwei , Wiezorek J. M. K. , Knapp J. A. , Follstaedt D. M. , Stach E. A. , Mao S. X.
Published: March 2008

We have used nanobeam electron diffraction to monitor the behavior of individual grains in nanocrystalline Ni during in situ tensile straining in the transmission electron microscope. The diffraction patterns reveal large variations in the magnitude of grain rotation and indicate that grain interiors can experience large lattice distortions (up to 5.5% linear strain). These large distortions may assist grain rearrangement during grain boundary facilitated deformation and are consistent with the behavior expected of nanocrystalline Ni near its predicted peak in strength.
Transient electric fields in laser plasmas observed by proton streak deflectometry
Authors: Sokollik T. , Schnürer M. , Ter-Avetisyan S. , Nickles P. V. , Risse E. , Kalashnikov M. , Sandner W. , Priebe G. , Amin M. , Toncian T. , Willi O. , Andreev A. A.
Published: March 2008

A novel proton imaging technique was applied which allows a continuous temporal record of electric fields within a time window of several nanoseconds. This “proton streak deflectometry” was used to investigate transient electric fields of intense (∼1017W∕cm2) laser irradiated foils. We found out that these fields with an absolute peak of up to 108V∕m extend over millimeter lateral extension and decay at nanosecond duration. Hence, they last much longer than the (approximately picosecond) laser excitation and extend much beyond the laser irradiation focus.
Multilayer organic solar cells with wet-processed polymeric bulk heterojunction film and dry-processed small molecule films
Authors: Kim Youngkyoo , Shin Minjung , Lee Inhyuk , Kim Hwajeong , Heutz Sandrine
Published: March 2008

Here, we report multilayer organic solar cells fabricated using a mix of solution (wet) and thermal evaporation (dry) techniques, which consist of indium-tin oxide (ITO), poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), poly(3-hexylthiophene) (P3HT):1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C61 (PCBM), C60, bathocuproine (BCP), and aluminum layers. Results show that the short circuit current density (JSC) of a ITO∕PEDOT:PSS∕C60/BCP/Al device was greatly improved by inserting a pristine P3HT light-absorbing layer between the PEDOT:PSS and C60 layers. Addition of PCBM to the P3HT layer lowered the JSC in the devices compared to the pristine P3HT layer and, in general, the JSC continued to decline with increasing PCBM content.
Terahertz wave reference-free phase imaging for identification of explosives
Authors: Zhang Liangliang , Zhong Hua , Deng Chao , Zhang Cunlin , Zhao Yuejin
Published: March 2008

We present terahertz reference-free phase imaging for identification of three explosive materials (HMX, RDX, and DNT. We propose a feature extraction technique to locate the spectral position of an unknown material’s absorption lines without using the reference signal. The samples are identified by their absorption peaks extracted from the negative first-order derivative of the sample signal phase divided by the frequency at each pixel. This technique will greatly benefit the future development of standoff distance, large size focal-plane terahertz imaging system.
Accurate measurement of the specific absorption rate using a suitable adiabatic magnetothermal setup
Authors: Natividad Eva , Castro Miguel , Mediano Arturo
Published: March 2008

Accurate measurements of the specific absorption rate (SAR) of solids and fluids were obtained by a calorimetric method, using a special-purpose setup working under adiabatic conditions. Unlike in current nonadiabatic setups, the weak heat exchange with the surroundings allowed a straightforward determination of temperature increments, avoiding the usual initial-time approximations. The measurements performed on a commercial magnetite aqueous ferrofluid revealed a good reproducibility (4%). Also, the measurements on a copper sample allowed comparison between experimental and theoretical values: adiabatic conditions gave SAR values only 3% higher than the theoretical ones, while the typical nonadiabatic method underestimated SAR by 21%.
Precision transport and assembling of nanowires in suspension by electric fields
Authors: Fan D. L. , Cammarata R. C. , Chien C. L.
Published: March 2008

We describe a method of precision transport of nanowires in suspension using a combination of dielectrophoretic force and electrophoretic force, which, respectively, aligns and transports the nanowires. The transport of nanowires can be made to follow any prescribed trajectory with any orientation by the voltages applied to the patterned electrodes. The same method applies to multiwall carbon nanotubes as well. We have joined end to end two oppositely charged nanowires separated by 200μm into a microelectromechanical device.
Trangie wallaby grass [Austrodanthonia caespitosa (Gaudich.) H.P. Linder]
Authors: Waters C. , Dear B. , Hackney B. , Jessop P. , Melville G.
Published: March 2008

Trangie wallaby grass, Austrodanthonia caespitosa (Dc1), is a composite of wild ecotypes collected from western New South Wales. A. caespitosa is a widespread native grass adapted to a broad range of environmental conditions but is particularly suited to low rainfall (300–450 mm) areas of south-eastern Australia. In this region, this cultivar has a demonstrated superior persistence to its close relative A. richardsonii (Cashmore) H.P. Linder cv. Taranna and the widely used pasture species, phalaris (Phalaris aquatica cv. Sirolan) and cocksfoot (Dactylis glomerata cv. Currie). This superior persistence was apparent in its ability to recruit new seedlings, even under summer drought conditions. Trangie wallaby grass was maintained under seed increase for 5 years at Trangie Agricultural Research Centre and subsequently at Dareton Agricultural and Advisory Station for 3 years.
Thioredoxin-mediated reversible dissociation of a stromal multiprotein complex in response to changes in light availability
Authors: Howard Thomas P. , Metodiev Metodi , Lloyd Julie C. , Raines Christine A.
Published: March 2008

A Calvin cycle multiprotein complex including phosphoribulokinase (PRK), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and a small protein, CP12, has previously been identified. In this article, we have studied this complex in leaves and have shown that dissociation and reassociation of the PRK/GAPDH/CP12 complex occurs in a time frame of minutes, allowing for rapid regulation of enzyme activity. Furthermore, we have shown that the extent of formation and dissociation of the PRK/GAPDH/CP12 complex correlates with the quantity of light. These data provide evidence linking the status of this complex with the rapid and subtle regulation of GAPDH and PRK activities in response to fluctuations in light availability. We have also demonstrated that dissociation of this complex depends on electron transport chain activity and that the major factor involved in the dissociation of the pea complex was thioredoxin
f
. We show here that both PRK and GAPDH are present in the reduced form in leaves in the dark, but are inactive, demonstrating the role of the PRK/GAPDH/CP12 complex in deactivating these enzymes in response to reductions in light intensity. Based on our data, we propose a model for thioredoxin
f
-mediated activation of PRK and GAPDH by two mechanisms: directly through reduction of disulfide bonds within these enzymes and indirectly by mediating the breakdown of the complex in response to changes in light intensity.
Txnip balances metabolic and growth signaling via PTEN disulfide reduction
Authors: Hui Simon T. Y. , Andres Allen M. , Miller Amber K. , Spann Nathanael J. , Potter Douglas W. , Post Noah M. , Chen Amelia Z. , Sachithanantham Sowbarnika , Jung Dae Young , Kim Jason K. , Davis Roger A.
Published: March 2008

Thioredoxin-interacting protein (Txnip) inhibits thioredoxin NADPH-dependent reduction of protein disulfides. Total Txnip knockout (TKO) mice adapted inappropriately to prolonged fasting by shifting fuel dependence of skeletal muscle and heart from fat and ketone bodies to glucose. TKO mice exhibited increased Akt signaling, insulin sensitivity, and glycolysis in oxidative tissues (skeletal muscle and hearts) but not in lipogenic tissues (liver and adipose tissue). The selective activation of Akt in skeletal muscle and hearts was associated with impaired mitochondrial fuel oxidation and the accumulation of oxidized (inactive) PTEN, whose activity depends on reduction of two critical cysteine residues. Whereas muscle- and heart-specific Txnip knockout mice recapitulated the metabolic phenotype exhibited by TKO mice, liver-specific Txnip knockout mice were similar to WT mice. Embryonic fibroblasts derived from knockout mice also accumulated oxidized (inactive) PTEN and had elevated Akt phosphorylation. In addition, they had faster growth rates and increased dependence on anaerobic glycolysis due to impaired mitochondrial fuel oxidation, and they were resistant to doxorubicin-facilitated respiration-dependent apoptosis. In the absence of Txnip, oxidative inactivation of PTEN and subsequent activation of Akt attenuated mitochondrial respiration, resulting in the accumulation of NADH, a competitive inhibitor of thioredoxin NADPH-reductive activation of PTEN. These findings indicate that, in nonlipogenic tissues, Txnip is required to maintain sufficient thioredoxin NADPH activity to reductively reactivate oxidized PTEN and oppose Akt downstream signaling.
Making primary connections: the cross‐curriculum story
Authors: Boyle Bill , Bragg Joanna
Published: March 2008

Using longitudinal curriculum data which they have collected over a ten year period from a nationally representative sample of primary schools (funded by grants from the Qualifications and Curriculum Authority), the authors report on evidence of changing models of subject provision within the primary curriculum. The period 1997–2007 has evidenced a range of government interventions with implications for subject teaching and data enable the analysis and discussion of the impact of these interventions on the ways in which sample schools have organised and planned their curriculum.
Semi-compactness of positive Dunford–Pettis operators on Banach lattices
Authors: Aqzzouz Belmesnaoui , Nouira Redouane , Zraoula Larbi
Published: March 2008

We investigate Banach lattices on which each positive Dunford–Pettis operator is semi-compact and the converse. As an interesting consequence, we obtain Theorem 2.7 of Aliprantis–Burkinshaw and an element of Theorem 1 of Wickstead.
Lifting endomorphisms to automorphisms
Authors: Arveson William , Courtney Dennis
Published: March 2008

Normal endomorphisms of von Neumann algebras need not be extendable to automorphisms of a larger von Neumann algebra, but they always have asymptotic lifts. We describe the structure of endomorphisms and their asymptotic lifts in some detail, and apply those results to complete the identification of asymptotic lifts of unital completely positive linear maps on von Neumann algebras in terms of their minimal dilations to endomorphisms.
Iterating the Cesàro operators
Authors: Galaz Fontes Fernando , Solís Francisco
Published: March 2008

The discrete Cesàro operator

C
C

associates to a given complex sequence

s
=
{

s
n

}

s = \{s_n\}

the sequence

C
s
≡
{

b
n

}

Cs \equiv \{b_n \}

, where

b
n

=

s
0

+
⋯
+

s
n

n
+
1

,
n
=
0
,
1
,
…

b_n = \frac {s_0 + \dots + s_n}{n +1}, n = 0, 1, \ldots

. When

s
s

is a convergent sequence we show that

{

C
n

s
}

\{C^n s \}

converges under the sup-norm if, and only if,

s
0

=

lim

n
→
∞

s
n

s_0 = \lim _{n\rightarrow \infty } s_n

. For its adjoint operator

C
∗

C^*

, we establish that

{
(

C
∗

)
n

s
}

\{(C^*)^n s\}

converges for any

s
∈

ℓ
1

s \in \ell ^1

. The continuous Cesàro operator,

C

f
(
x
)
 
≡
 

1
x

∫

0

x

f
(
s
)
d
s

C\!f (x) \ \equiv \ \frac {1}{x} \int _{0}^ {x}\, f(s) ds

, has two versions: the finite range case is defined for

f
∈

L
∞

(
0
,
1
)

f \in L^\infty (0,1)

and the infinite range case for

f
∈

L
∞

(
0
,
∞
)

f \in L^\infty (0, \infty )

. In the first situation, when

f
:
[
0
,
1
]
→

C

f: [0, 1] \rightarrow \mathbb {C}

is continuous we prove that

{

C
n

f
}

\{C^n f \}

converges under the sup-norm to the constant function

f
(
0
)

f(0)

. In the second situation, when

f
:
[
0
,
∞
)
→

C

f: [0, \infty )\rightarrow \mathbb {C}

is a continuous function having a limit at infinity, we prove that

{

C
n

f
}

\{C^n f \}

converges under the sup-norm if, and only if,

f
(
0
)
=

lim

x
→
∞

f
(
x
)

f(0) = \lim _{x\rightarrow \infty }f(x)

.
A decomposition theorem for frames and the Feichtinger Conjecture
Authors: Casazza Peter , Kutyniok Gitta , Speegle Darrin , Tremain Janet
Published: March 2008

In this paper we study the Feichtinger Conjecture in frame theory, which was recently shown to be equivalent to the 1959 Kadison-Singer Problem in

C

∗

C^{*}

-Algebras. We will show that every bounded Bessel sequence can be decomposed into two subsets each of which is an arbitrarily small perturbation of a sequence with a finite orthogonal decomposition. This construction is then used to answer two open problems concerning the Feichtinger Conjecture: 1. The Feichtinger Conjecture is equivalent to the conjecture that every unit norm Bessel sequence is a finite union of frame sequences. 2. Every unit norm Bessel sequence is a finite union of sets each of which is

ω
\omega

-independent for

ℓ
2

\ell _2

-sequences.
A generating function for Blattner’s formula
Authors: Willenbring Jeb , Zuckerman Gregg
Published: March 2008

Let

G
G

be a connected, semisimple Lie group with finite center and let

K
K

be a maximal compact subgroup. We investigate a method to compute multiplicities of

K
K

-types in the discrete series using a rational expression for a generating function obtained from Blattner’s formula. This expression involves a product with a character of an irreducible finite-dimensional representation of

K
K

and is valid for any discrete series system. Other results include a new proof of a symmetry of Blattner’s formula, and a positivity result for certain low rank examples. We consider in detail the situation for

G
G

of type split

G
2

\rm G_2

. The motivation for this work came from an attempt to understand pictures coming from Blattner’s formula, some of which we include in the paper.
Rational homotopy type of subspace arrangements with a geometric lattice
Authors: Debongnie Gery
Published: March 2008

Let

A

=
{

x
1

,
…
,

x
n

}

\mathcal {A} = \{x_1, \dotsc , x_n\}

be a subspace arrangement with a geometric lattice such that

codim
⁡
(
x
)
≥
2

\operatorname {codim}(x) \geq 2

for every

x
∈

A

x \in \mathcal {A}

. Using rational homotopy theory, we prove that the complement

M
(

A

)

M(\mathcal {A})

is rationally elliptic if and only if the sum

x
1
⊥

+
…
+

x
n
⊥

x_1^\perp + \dotso + x_n^\perp

is a direct sum. The homotopy type of

M
(

A

)

M(\mathcal {A})

is also given: it is a product of odd-dimensional spheres. Finally, some other equivalent conditions are given, such as Poincaré duality. Those results give a complete description of arrangements (with a geometric lattice and with the codimension condition on the subspaces) such that

M
(

A

)

M(\mathcal {A})

is rationally elliptic, and show that most arrangements have a hyperbolic complement.
On Mirković-Vilonen cycles and crystal combinatorics
Authors: Baumann Pierre , Gaussent Stéphane
Published: March 2008

Let

G
G

be a complex connected reductive group and let

G

∨

G^{\vee }

be its Langlands dual. Let us choose a triangular decomposition

n

−
,

∨

⊕

h

∨

⊕

n

+
,

∨

{\mathfrak n}^{-,{\vee }} \oplus {\mathfrak h}^{\vee }\oplus {\mathfrak n}^{+,{\vee }}

of the Lie algebra of

G

∨

G^{\vee }

. Braverman, Finkelberg and Gaitsgory show that the set of all Mirković-Vilonen cycles in the affine Grassmannian
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper G left-parenthesis double-struck upper C left-parenthesis left-parenthesis t right-parenthesis right-parenthesis right-parenthesis slash upper G left-parenthesis double-struck upper C left-bracket left-bracket t right-bracket right-bracket right-parenthesis">

G

(

C

(
(
t
)
)

)

/

G

(

C

[
[
t
]
]

)

G\bigl (\mathbb C((t))\bigr )/G\bigl (\mathbb C[[t]]\bigr )

is a crystal isomorphic to the crystal of the canonical basis of

U
(

n

+
,

∨

)

U({\mathfrak n}^{+,{\vee }})

. Starting from the string parameter of an element of the canonical basis, we give an explicit description of a dense subset of the associated MV cycle. As a corollary, we show that the varieties involved in Lusztig’s algebraic-geometric parametrization of the canonical basis are closely related to MV cycles. In addition, we prove that the bijection between LS paths and MV cycles constructed by Gaussent and Littelmann is an isomorphism of crystals.
Interplay between S-Cyclin-dependent Kinase and Dbf4-dependent Kinase in Controlling DNA Replication through Phosphorylation of Yeast Mcm4 N-Terminal Domain
Authors: Devault Alain , Gueydon Elisabeth , Schwob Etienne
Published: March 2008

Cyclin-dependent (CDK) and Dbf4-dependent (DDK) kinases trigger DNA replication in all eukaryotes, but how these kinases cooperate to regulate DNA synthesis is largely unknown. Here, we show that budding yeast Mcm4 is phosphorylated in vivo during S phase in a manner dependent on the presence of five CDK phosphoacceptor residues within the N-terminal domain of Mcm4. Mutation to alanine of these five sites (mcm4-5A) abolishes phosphorylation and decreases replication origin firing efficiency at 22°C. Surprisingly, the loss of function mcm4-5A mutation confers cold and hydroxyurea sensitivity to DDK gain of function conditions (mcm5/bob1 mutation or DDK overexpression), implying that phosphorylation of Mcm4 by CDK somehow counteracts negative effects produced by ectopic DDK activation. Deletion of the S phase cyclins Clb5,6 is synthetic lethal with mcm4-5A and mimics its effects on DDK up mutants. Furthermore, we find that Clb5 expressed late in the cell cycle can still suppress the lethality of clb5,6Δ bob1 cells, whereas mitotic cyclins Clb2, 3, or 4 expressed early cannot. We propose that the N-terminal extension of eukaryotic Mcm4 integrates regulatory inputs from S-CDK and DDK, which may play an important role for the proper assembly or stabilization of replisome–progression complexes.
The Yak1 Kinase Is Involved in the Initiation and Maintenance of Hyphal Growth inCandida albicans
Authors: Goyard Sophie , Knechtle Philipp , Chauvel Murielle , Mallet Adeline , Prévost Marie-Christine , Proux Caroline , Coppée Jean-Yves , Schwarz Patrick , Dromer Françoise , Park Hyunsook , Filler Scott G. , Janbon Guilhem , d'Enfert Christophe
Published: March 2008

Members of the dual-specificity tyrosine-phosphorylated and regulated kinase (DYRK) family perform a variety of functions in eukaryotes. We used gene disruption, targeted pharmacologic inhibition, and genome-wide transcriptional profiling to dissect the function of the Yak1 DYRK in the human fungal pathogen Candida albicans. C. albicans strains with mutant yak1 alleles showed defects in the yeast-to-hypha transition and in maintaining hyphal growth. They also could not form biofilms. Despite their in vitro filamentation defect, C. albicans yak1Δ/yak1Δ mutants remained virulent in animal models of systemic and oropharyngeal candidiasis. Transcriptional profiling showed that Yak1 was necessary for the up-regulation of only a subset of hypha-induced genes. Although downstream targets of the Tec1 and Bcr1 transcription factors were down-regulated in the yak1Δ/yak1Δ mutant, TEC1 and BCR1 were not. Furthermore, 63% of Yak1-dependent, hypha-specific genes have been reported to be negatively regulated by the transcriptional repressor Tup1 and inactivation of TUP1 in the yak1Δ/yak1Δ mutant restored filamentation, suggesting that Yak1 may function upstream of Tup1 in governing hyphal emergence and maintenance.
Inference of biochemical network models in S-system using multiobjective optimization approach
Authors: Liu Pang-Kai , Wang Feng-Sheng
Published: March 2008

Motivation: The inference of biochemical networks, such as gene regulatory networks, protein–protein interaction networks, and metabolic pathway networks, from time-course data is one of the main challenges in systems biology. The ultimate goal of inferred modeling is to obtain expressions that quantitatively understand every detail and principle of biological systems. To infer a realizable S-system structure, most articles have applied sums of magnitude of kinetic orders as a penalty term in the fitness evaluation. How to tune a penalty weight to yield a realizable model structure is the main issue for the inverse problem. No guideline has been published for tuning a suitable penalty weight to infer a suitable model structure of biochemical networks.

Results: We introduce an interactive inference algorithm to infer a realizable S-system structure for biochemical networks. The inference problem is formulated as a multiobjective optimization problem to minimize simultaneously the concentration error, slope error and interaction measure in order to find a suitable S-system model structure and its corresponding model parameters. The multiobjective optimization problem is solved by the ε-constraint method to minimize the interaction measure subject to the expectation constraints for the concentration and slope error criteria. The theorems serve to guarantee the minimum solution for the ε-constrained problem to achieve the minimum interaction network for the inference problem. The approach could avoid assigning a penalty weight for sums of magnitude of kinetic orders.

Contact:  chmfsw@ccu.edu.tw

Supplementary information: Supplementary data are available at Bioinformatics online.
e-LiSe—an online tool for finding needles in the ‘(Medline) haystack’
Authors: Gladki Arek , Siedlecki Pawel , Kaczanowski Szymon , Zielenkiewicz Piotr
Published: March 2008

Summary: Using literature databases one can find not only known and true relations between processes but also less studied, non-obvious associations. The main problem with discovering such type of relevant biological information is ‘selection’. The ability to distinguish between a true correlation (e.g. between different types of biological processes) and random chance that this correlation is statistically significant is crucial for any bio-medical research, literature mining being no exception. This problem is especially visible when searching for information which has not been studied and described in many publications. Therefore, a novel bio-linguistic statistical method is required, capable of ‘selecting’ true correlations, even when they are low-frequency associations. In this article, we present such statistical approach based on Z-score and implemented in a web-based application ‘e-LiSe’.

Availability: The software is available at http://miron.ibb.waw.pl/elise/

Contact:  piotr@ibb.waw.pl

Supplementary information: Supplementary materials are available at http://miron.ibb.waw.pl/elise/supplementary/
Global zoogeography of fragile macrozooplankton in the upper 100–1000 m inferred from the underwater video profiler
Authors: Stemmann Lars , Youngbluth Marsh , Robert Kevin , Hosia Aino , Picheral Marc , Paterson Harriet , Ibanez Frederic , Guidi Lionel , Lombard Fabien , Gorsky Gabriel
Published: March 2008

Stemmann, L., Youngbluth, M., Robert, K., Hosia, A., Picheral, M., Paterson, H., Ibanez, F., Guidi, L., Lombard, F., and Gorsky, G. 2008. Global zoogeography of fragile macrozooplankton in the upper 100–1000 m inferred from the underwater video profiler. – ICES Journal of Marine Science, 65: 433–442. Mesopelagic gelatinous zooplankton fauna are insufficiently known because of inappropriate and infrequent sampling, but may have important trophic roles. In situ imaging systems and undersea vehicles have been used to investigate their diversity, distribution, and abundance. The use of different platforms, however, restricts the comparison of data from different regions. Starting in 2001, the underwater video profiler (UVP) was deployed during 12 cruises in six oceanic regimes (Mediterranean Sea, North Atlantic shelves, Mid-Atlantic Ridge, tropical Pacific Ocean, eastern Indian Ocean, and Subantarctic Ocean) to determine the vertical distribution of organisms in the upper 1000 m. Nine oceanic regions were identified based on the hydrological properties of the water column. They correspond to nine of the biogeochemical provinces defined by Longhurst. In all, 21 morphotypes were recognized: sarcodines (eight groups), ctenophores (two groups), siphonophores, medusae (five groups), crustaceans (one group), chaetognaths, appendicularians, salps, and fish. The similarity in the community assemblages of zooplankton in the 100–1000 m layer was significantly greater within regions than between regions, in most cases. The regions with comparable composition were located in the North Atlantic with adjacent water masses, suggesting that the assemblages were either mixed by advective transport or that environmental conditions were similar in mesopelagic layers. The data suggest that the spatial structuring of mesopelagic macrozooplankton occurs on large scales (e.g. basin scales) but not necessarily on smaller scales (e.g. oceanic front).
Temporal Increase and Spatial Distribution of Sugarcane Yellow Leaf and Infestations of the Aphid Vector, Melanaphis sacchari
Authors: McAllister C. D. , Hoy J. W. , Reagan T. E.
Published: March 2008

Yellow leaf, caused by Sugarcane yellow leaf virus (ScYLV), is a potentially important disease of sugarcane first found in Louisiana during 1996. A survey during 2002 determined that ScYLV infection was present in all sugarcane-production areas of Louisiana. Virus was detected in 48% of 42 fields, and incidence averaged 15% in these fields. Disease progress curves determined in four fields during two growing seasons indicated that the greatest temporal increase of virus infection occurred during late spring and early summer and coincided with the initial infestation and increase of the virus vector, the sugarcane aphid (Melanaphis sacchari). Aphid infestations in the experimental fields during 2002 and 2003 ranged from 1.2 to 33.0 and 1.0 to 4.2 aphids per leaf, respectively. Final disease incidences of 2.9, 5.2, and 5.2% were recorded in three fields planted with virus-free seed-cane. Distribution of ScYLV infections and aphids evaluated with spatial autocorrelation analysis indicated that ScYLV and its aphid vector both exhibited a predominantly random spatial distribution, with occasional aggregation. The low incidence and rates of disease increase observed, despite the widespread occurrence of potential vectors, suggest that inoculum pressure remains low in Louisiana. Therefore, it may be possible to keep yellow leaf at low levels by planting virus-free seed-cane.
Arabidopsis Ribosomal Proteins RPL23aA and RPL23aB Are Differentially Targeted to the Nucleolus and Are Disparately Required for Normal Development
Authors: Degenhardt Rory F. , Bonham-Smith Peta C.
Published: March 2008

Protein synthesis is catalyzed by the ribosome, a two-subunit enzyme comprised of four ribosomal RNAs and, in Arabidopsis (Arabidopsis thaliana), 81 ribosomal proteins (r-proteins). Plant r-protein genes exist as families of multiple expressed members, yet only one r-protein from each family is incorporated into any given ribosome, suggesting that many r-protein genes may be functionally redundant or development/tissue/stress specific. Here, we characterized the localization and gene-silencing phenotypes of a large subunit r-protein family, RPL23a, containing two expressed genes (RPL23aA and RPL23aB). Live cell imaging of RPL23aA and RPL23aB in tobacco with a C-terminal fluorescent-protein tag demonstrated that both isoforms accumulated in the nucleolus; however, only RPL23aA was targeted to the nucleolus with an N-terminal fluorescent protein tag, suggesting divergence in targeting efficiency of localization signals. Independent knockdowns of endogenous RPL23aA and RPL23aB transcript levels using RNA interference determined that an RPL23aB knockdown did not alter plant growth or development. Conversely, a knockdown of RPL23aA produced a pleiotropic phenotype characterized by growth retardation, irregular leaf and root morphology, abnormal phyllotaxy and vasculature, and loss of apical dominance. Comparison to other mutants suggests that the phenotype results from reduced ribosome biogenesis, and we postulate a link between biogenesis, microRNA-target degradation, and maintenance of auxin homeostasis. An additional RNA interference construct that coordinately silenced both RPL23aA and RPL23aB demonstrated that this family is essential for viability.
Loss of phospholipid membrane asymmetry and sialylated glycoconjugates from erythrocyte surface in haemoglobin E β‐thalassaemia
Authors: Basu Sumanta , Banerjee Debasis , Chandra Sarmila , Chakrabarti Abhijit
Published: March 2008

This study aimed to investigate any correlation between the extent of phosphatidylserine (PS) asymmetry and sialylated glycoconjugate levels with the faster clearance of circulating erythrocytes in haemoglobin E (HbE) β‐thalassaemia. Erythrocytes from peripheral blood samples of different HbEβ‐thalassaemia patients showed loss of PS asymmetry measured by annexin V binding using flow cytometry. Maximum PS exposure was found when HbE was 50–60% and HbF was <20% indicating a possible correlation with severity of the disease. Separation of erythrocytes into aged and younger cells showed higher loss of PS asymmetry in the younger erythrocytes of HbEβ‐thalassaemia patients when compared with normal blood, where PS asymmetry was lost only in the older cells. Sialylated glycoconjugate measurement using the lectins wheatgerm agglutinin and pokeweed mitogen showed loss of sialic acid and N‐acetyl‐d‐glucosamine‐bearing glycoproteins in the order normal<homozygous E<HbEβ‐thalassaemic upon ageing. A possible correlation was found between the loss of PS asymmetry with HbE level and the reduction of glycophorins from the cell surface, mediated by membrane vesiculation. A more facilitated vesiculation process in HbEβ‐thalassaemic erythrocytes could lead to faster shedding of glycophorin‐containing microvesicles, leaving highly PS‐exposed erythrocytes accessible to phagocytes.
Expression of the human germinal‐centre‐associated lymphoma protein in diffuse large B‐cell lymphomas in patients with rheumatoid arthritis
Authors: Baecklund Eva , Natkunam Yasodha , Backlin Carin , Iliadou Anastasia , Askling Johan , Ekbom Anders , Feltelius Nils , Klareskog Lars , Enblad Gunilla , Lossos Izidore S. , Levy Ronald , Sundström Christer , Rosenquist Richard
Published: March 2008

Diffuse large B‐cell lymphomas (DLBCL) can be subdivided into germinal centre (GC)‐like and non‐GC‐like subtypes by CD10, BCL6 and MUM1/IRF4 status. We previously reported that patients with severe rheumatoid arthritis (RA) are at increased risk of non‐GC DLBCL. This study examined a new GC‐marker, human germinal‐centre‐associated lymphoma (HGAL) protein, in RA‐DLBCL. Of 111, 38 (34%) DLBCL were HGAL‐positive and showed less disseminated disease and a tendency toward improved overall survival compared to HGAL‐negative cases. This supports that a majority of RA‐DLBCL are of non‐GC origin, indicating a specific role for activated peripheral B cells in the pathogenesis of RA‐DLBCL.
Alternate day pomalidomide retains anti‐myeloma effect with reduced adverse events and evidence of in vivo immunomodulation
Authors: Streetly Matthew J. , Gyertson Kylie , Daniel Yvonne , Zeldis Jerome B. , Kazmi Majid , Schey Stephen A.
Published: March 2008

We previously reported that daily dose pomalidomide (CC‐4047), a thalidomide analogue, has excellent anti‐myeloma activity but is associated with myelosuppression and deep vein thrombosis. We report here a phase 1 study to determine the maximum tolerated dose (MTD) of pomalidomide at 1 mg, 2 mg, 5 mg and 10 mg on alternate days (ad). Twenty patients with relapsed myeloma were treated. Grade 4 neutropenia occurred in all patients receiving 10 mg and the MTD was defined as 5 mg ad. No thrombotic events were observed. Pomalidomide was continued following the 4‐week MTD study in 17/20 patients for a median of 14 months. 10% of patients had a complete response and >50% reduction in paraprotein was achieved in 50% of subjects. Progression‐free survival was 10·5 months and median overall survival was 33 months. A significant rise was observed in the proportion of CD8+ cells. Alternate day pomalidomide was associated with a marked reduction in the incidence of thrombosis whilst maintaining excellent anti‐myeloma activity. This trial provides further in vivo evidence that pomalidomide modulates the immune system in myeloma patients. Phase 2 studies to further assess the optimal schedule of administration and anti‐myeloma activity of this agent are planned.
Adverse outcomes of blood transfusion in children: analysis of UK reports to the serious hazards of transfusion scheme 1996–2005
Authors: Stainsby D. , Jones H. , Wells A. W. , Gibson B. , Cohen H. ,   on behalf of the SHOT Steering Group
Published: March 2008

Between 1996 and 2005 the Serious Hazards of Transfusion (SHOT) scheme analysed 3239 reports of adverse reactions and events associated with transfusion of labile blood components in the UK. 321 reports (10%) related to transfusion of children under 18 years and 147/3239 (4·5%) to infants less than 12 months of age. There were 264 cases in children of ‘incorrect blood component transfused’, resulting from errors at all stages in the transfusion chain; 26/264 suffered actual or potential morbidity. Thirty acute transfusion reactions, three delayed transfusion reactions, 20 cases (three fatal) of transfusion‐related acute lung injury, two cases (both fatal) of transfusion‐associated graft‐versus‐host disease and two transfusion transmitted infections were reported. A population‐based epidemiological study of transfused patients in 2004 showed that 4·2% of red cells are transfused to patients less than 18 years and 1·7% to infants less than 12 months. Interpretation of SHOT data against this context enabled the estimation of the incidence of an adverse outcome to be 18:100 000 red cells issued for children less than 18 years and 37:100 000 for infants less than 12 months, compared to 13:100 000 for adults. Adherence to relevant guidelines, knowledge of specialist transfusion needs of children and good communication are essential if this risk is to be reduced.