3,273 research outputs found
DC-bias for Optical OFDM in Visible Light Communications
The requirement of a DC-bias is known to make DC-biased Optical Orthogonal Frequency Division Multiplexing (DCO-OFDM) less energy efficient. This can be improved by Asymmetrically Clipped Optical OFDM (ACO-OFDM), Pulse Amplitude Modulated OFDM (PAM-OFDM) or Flip-OFDM, but these variants use the bandwidth inefficiently. Our trade-off between energy and spectrum efficiency considers a given limited channel bandwidth of the Light Emitting Diode (LED) and then attempts to get the highest throughput per unit of energy. We investigate previous findings that clipped OFDM can be more attractive in a low-SNR regime. More specifically, we consider Visible Light Communication (VLC) in which the average light level, i.e., the bias, is prescribed by illumination requirements, thus comes for free. ACO/PAM/Flip-OFDM can convert the DC-bias into power for communication, but all variants of OFDM, including DCO-OFDM consume extra electrical power. We conclude that in this scenario, advantages attributed to ACO/PAM/Flip-OFDM vanish, as DCO-OFDM outperforms its variants in all SNR conditions, in terms of achieved throughput over a bandlimited channel as a function of extra electrical power required. For hybrid solutions, such as Asymmetrically clipped DC biased Optical OFDM (ADO-OFDM) and Hybrid ACO-OFDM (HACO-OFDM), we optimize a new adaptive power and rate splitting between odd (clipped) and even (biased/clipped) subcarriers to balance power and bandwidth efficiency
Effects of substrate curvature radius, deposition temperature and coating thickness on the residual stress field of cylindrical thermal barrier coatings
In a thermal barrier coating (TBC) system with cylindrical geometry, the position of coating plays an important role in the distribution of residual stress. In this paper, the residual stress field in three different types of TBCs with cylindrical geometry has been analyzed. The main focus is on the effects of substrate curvature radius, deposition temperature and coating thickness on the residual stress distribution during a deposition process. The results show that the substrate curvature radius significantly affects the distributions of radial and hoop residual stresses, which are in good agreement with experimental measurements by photo-stimulated luminescence piezospectroscopy (Wang et al., Acta Mater., 2009, 57(1):182–195). The maximum radial residual stress locates closely to the coating/thermal grown oxide interface. However, the maximum hoop residual stress lies in the thermal grown oxide layer, which is much more than other three layers and presents a strong stress singularity along the thickness direction
Oma1 Links Mitochondrial Protein Quality Control and TOR Signaling To Modulate Physiological Plasticity and Cellular Stress Responses
ACKNOWLEDGMENTS We thank Dennis Winge (University of Utah) and the members of the Khalimonchuk laboratory for critical comments. We also thank Christoph Schuller (University of Natural Resources, Austria) and Paul Herman (Ohio State University) for reagents. We acknowledge the expert technical assistance of Nataliya Zahayko. We also thank Donna MacCallum for help with the Candida virulence assays. This research was supported by grants from the NIH (P30GM103335 and 5R01GM108975 [O.K.], GM071775-06 and GM105781-01 [A.B.], DK079209 [J.L.]), the U.K. Biotechnology and Biological Research Council (BB/K017365/1 [A.J.P.B.]), the U.K. Medical Research Council (MR/ M026663/1 [A.J.P.B.]), and the European Research Council (C-2009- AdG-249793 [A.J.P.B.]). We declare that we have no competing financial interests. FUNDING INFORMATION This work, including the efforts of Alistair J. P. Brown, was funded by Biotechnology and Biological Research Counsil (BB/K017365/1). This work, including the efforts of Oleh Khalimonchuk, was funded by HHS | National Institutes of Health (NIH) (5R01GM108975). This work, including the efforts of Oleh Khalimonchuk, was funded by HHS | National Institutes of Health (NIH) (P30GM103335).This work, including the efforts of Antoni Barrientos, was funded by HHS | National Institutes of Health (NIH) (GM071775-06). This work, including the efforts of Antoni Barrientos, was funded by HHS | National Institutes of Health (NIH) (GM105781-01). This work, including the efforts of Jaekwon Lee, was funded by HHS | National Institutes of Health (NIH) (DK079209). This work, including the efforts of Alistair J. P. Brown, was funded by Medical Research Council (MRC) (MR/M026663/1). This work, including the efforts of Alistair J. P. Brown, was funded by EC | European Research Council (ERC) (C-2009-AdG-249793).Peer reviewedPublisher PD
Scale Dependence of Twist-3 Quark-Gluon Operators for Single Spin Asymmetries
We derive the scale dependence of twist-3 quark-gluon operators, or ETQS
matrix elements, at one-loop. These operators are used to factorize transverse
single spin asymmetries, which are studied intensively both in experiment and
theory. The scale dependence of two special cases are particularly interesting.
One is of soft-gluon-pole matrix elements, another is of soft-quark-pole matrix
elements. From our results the evolutions in the two cases can be obtained. A
comparison with existing results of soft-gluon-pole matrix elements is made.Comment: typo in Eq.(10) corrected, references adde
Quantum Critical Behavior of Two Coupled Bose-Einstein Condensates
The quantum critical behavior of the Bose-Hubbard model for a description of
two coupled Bose-Einstein condensates is studied within the framework of an
algebraic theory. Energy levels, wavefunction overlaps with those of the Rabi
and Fock regimes, and the entanglement are calculated exactly as functions of
the phase parameter and the number of bosons. The results show that the system
goes though a phase transition and that the critical behavior is enhanced in
the thermodynamic limit.Comment: 6 pages, LaTex, 3 figure
Tibetan sheep are better able to cope with low energy intake than Small-tailed Han sheep due to lower maintenance energy requirements and higher nutrient digestibilities
Tibetan sheep are indigenous to the Qinghai-Tibetan Plateau (QTP) and are well-adapted to and even thrive under the harsh alpine conditions. Small-tailed Han sheep were introduced to the plateau because of their high prolificacy and are maintained mainly in feedlots. Because of their different backgrounds, we hypothesised that Tibetan and Small-tailed Han sheep would differ in their utilization of energy intake and predicted that Tibetan sheep would cope better with low energy intake than Small-tailed Han sheep. To test this prediction, we determined nutrient digestibilities, energy requirements for maintenance and blood metabolite and hormone concentrations involved in energy metabolism in these breeds. Sheep of each breed (n = 24 of each, all wethers and 1.5 years of age) were distributed randomly into one of four groups and offered ad libitum diets of different digestible energy (DE) densities: 8.21, 9.33, 10.45 and 11.57 MJ DE/kg Dry matter (DM). Following 42 d of measuring feed intake, a 1-week digestion and metabolism experiment was done. DM intakes did not differ between breeds nor among treatments but, by design, DE intake increased linearly in both breeds as dietary energy level increased (P < 0.001). The average daily gain (ADG) was significantly greater in the Tibetan than Small-tailed Han sheep (P = 0.003) and increased linearly in both breeds (P < 0.001). In addition, from the regression analysis of ADG on DE intake, daily DE maintenance requirements were lower for Tibetan than for Small-tailed Han sheep (0.41 vs 0.50 MJ/BW0.75, P < 0.05). The DE and metabolizable energy (ME) digestibilities were higher in the Tibetan than Small-tailed Han sheep (P < 0.001) and increased linearly as the energy level increased in the diet (P < 0.001). At the lowest energy treatment, Tibetan sheep when compared with Small-tailed Han sheep, had: 1) higher serum glucose and glucagon, but lower insulin concentrations (P < 0.05), which indicated a higher capacity for gluconeogenesis and ability to regulate glucose metabolism; and 2) higher non-esterified fatty acids (NEFA) and lower very low density lipoprotein (VLDL) and triglyceride (TG) concentrations (P < 0.05), which indicated a higher capacity for NEFA oxidation but lower ability for triglyceride (TG) synthesis. We concluded that our prediction was supported as these differences between breeds conferred an advantage for Tibetan over Small-tailed Han sheep to cope better with low energy diets
Theory of ac electrokinetic behavior of spheroidal cell suspensions with an intrinsic dispersion
The dielectric dispersion, dielectrophoretic (DEP) and electrorotational (ER)
spectra of spheroidal biological cell suspensions with an intrinsic dispersion
in the constituent dielectric constants are investigated. By means of the
spectral representation method, we express analytically the characteristic
frequencies and dispersion strengths both for the effective dielectric constant
and the Clausius-Mossotti factor (CMF). We identify four and six characteristic
frequencies for the effective dielectric spectra and CMF respectively, all of
them being dependent on the depolarization factor (or the cell shape). The
analytical results allow us to examine the effects of the cell shape, the
dispersion strength and the intrinsic frequency on the dielectric dispersion,
DEP and ER spectra. Furthermore, we include the local-field effects due to the
mutual interactions between cells in a dense suspension, and study the
dependence of co-field or anti-field dispersion peaks on the volume fractions.Comment: accepted by Phys. Rev.
Fuel inventory and deposition in castellated structures in JET-ILW
Since 2011 the JET tokamak has been operated with a metal ITER-like wall (JET-ILW) including
castellated beryllium limiters and lamellae-type bulk tungsten tiles in the divertor. This has allowed
for a large scale test of castellated plasma-facing components (PFC). Procedures for sectioning the
limiters into single blocks of castellation have been developed. This facilitated morphology studies
of morphology of surfaces inside the grooves for limiters after experimental campaigns 2011–2012
and 2013–2014. The deposition in the 0.4–0.5mm wide grooves of the castellation is ‘shallow’.
It reaches 1–2mm into the 12mm deep gap. Deuterium concentrations are small (mostly below
1 × 1018 cm−2
). The estimated total amount of deuterium in all the castellated limiters does not
exceed the inventory of the plasma-facing surfaces (PFS) of the limiters. There are only traces of
Ni, Cr and Fe deposited in the castellation gaps. The same applies to the carbon content. Also low
deposition of D, Be and C has been measured on the sides of the bulk tungsten lamellae pieces.
Modelling clearly reflects: (a) a sharp decrease in the measured deposition profiles and
(b) an increase in deposition with the gap width. Both experimental and modelling data give a strong
indication and information to ITER that narrow gaps in the castellated PFC are essential. X-ray
diffraction on PFS has clearly shown two distinct composition patterns: Be with an admixture of
Be–W intermetallic compounds (e.g. Be22W) in the deposition zone, whilst only pure Be has been detected in the erosion zone. The lack of compound formation in the erosion zone indicates that no distinct changes in the thermo-mechanical properties of the Be PFC might be expected.EURATOM 633053Swedish Research Council (VR) 2015–0484
Compact phases of polymers with hydrogen bonding
We propose an off-lattice model for a self-avoiding homopolymer chain with
two different competing attractive interactions, mimicking the hydrophobic
effect and the hydrogen bond formation respectively. By means of Monte Carlo
simulations, we are able to trace out the complete phase diagram for different
values of the relative strength of the two competing interactions. For strong
enough hydrogen bonding, the ground state is a helical conformation, whereas
with decreasing hydrogen bonding strength, helices get eventually destabilized
at low temperature in favor of more compact conformations resembling
-sheets appearing in native structures of proteins. For weaker hydrogen
bonding helices are not thermodynamically relevant anymore.Comment: 5 pages, 3 figures; revised version published in PR
Skyrmion Excitation in Two-Dimensional Spinor Bose-Einstein Condensate
We study the properties of coreless vortices(skyrmion) in spinor
Bose-Einstein condensate. We find that this excitation is always energetically
unstable, it always decays to an uniform spin texture. We obtain the skyrmion
energy as a function of its size and position, a key quantity in understanding
the decay process. We also point out that the decay rate of a skyrmion with
high winding number will be slower. The interaction between skyrmions and other
excitation modes are also discussed.Comment: 5 pages, 4 figures, final version published in Phys. Rev.
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