11,578 research outputs found
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A novel element upstream of the Vgamma2 gene in the murine T cell receptor gamma locus cooperates with the 3 enhancer to act as a locus control region.
Transgenic expression constructs were employed to identify a cis-acting transcription element in the T cell receptor (TCR)-gamma locus, called HsA, between the Vgamma5 and Vgamma2 genes. In constructs lacking the previously defined enhancer (3E(Cgamma1)), HsA supports transcription in mature but not immature T cells in a largely position-independent fashion. 3E(Cgamma1), without HsA, supports transcription in immature and mature T cells but is subject to severe position effects. Together, the two elements support expression in immature and mature T cells in a copy number-dependent, position-independent fashion. Furthermore, HsA was necessary for consistent rearrangement of transgenic recombination substrates. These data suggest that HsA provides chromatin-opening activity and, together with 3E(Cgamma1), constitutes a T cell-specific locus control region for the TCR-gamma locus
Detection and localization of continuous gravitational waves with pulsar timing arrays: the role of pulsar terms
A pulsar timing array is a Galactic-scale detector of nanohertz gravitational
waves (GWs). Its target signals contain two components: the `Earth term' and
the `pulsar term' corresponding to GWs incident on the Earth and pulsar
respectively. In this work we present a Frequentist method for the detection
and localization of continuous waves that takes into account the pulsar term
and is significantly faster than existing methods. We investigate the role of
pulsar terms by comparing a full-signal search with an Earth-term-only search
for non-evolving black hole binaries. By applying the method to synthetic data
sets, we find that (i) a full-signal search can slightly improve the detection
probability (by about five percent); (ii) sky localization is biased if only
Earth terms are searched for and the inclusion of pulsar terms is critical to
remove such a bias; (iii) in the case of strong detections (with
signal-to-noise ratio 30), it may be possible to improve pulsar
distance estimation through GW measurements.Comment: 12 pages, 9 figures, typos corrected. To match the published version.
Code implementing this method is available at the PPTA Wiki pag
Anomalous particle-number fluctuations in a three-dimensional interacting Bose-Einstein condensate
The particle-number fluctuations originated from collective excitations are
investigated for a three-dimensional, repulsively interacting Bose-Einstein
condensate (BEC) confined in a harmonic trap. The contribution due to the
quantum depletion of the condensate is calculated and the explicit expression
of the coefficient in the formulas denoting the particle-number fluctuations is
given. The results show that the particle-number fluctuations of the condensate
follow the law and the fluctuations vanish when
temperature approaches to the BEC critical temperature.Comment: RevTex, 4 page
Thermoelectric Properties of Intermetallic Semiconducting RuIn3 and Metallic IrIn3
Low temperature (<400 K) thermoelectric properties of semiconducting RuIn3
and metallic IrIn3 are reported. RuIn3 is a narrow band gap semiconductor with
a large n-type Seebeck coefficient at room temperature (S(290K)~400 {\mu}V/K),
but the thermoelectric Figure of merit (ZT(290K) = 0.007) is small because of
high electrical resistivity and thermal conductivity ({\kappa}(290 K) ~ 2.0 W/m
K). IrIn3 is a metal with low thermopower at room temperature (S(290K)~20
{\mu}V/K) . Iridium substitution on the ruthenium site has a dramatic effect on
transport properties, which leads to a large improvement in the power factor
and corresponding Figure of merit (ZT(380 K) = 0.053), improving the efficiency
of the material by an over of magnitude.Comment: Submitted to JA
Designing durable and flexible superhydrophobic coatings and its application in oil purification
Lotus-inspired superhydrophobic coatings are usually mechanically weak and lack durability, this hinders their practical applications. A suspension that can be treated on various materials in any size and shape to form a mechanically durable superhydrophobic coating is developed, which retains water repellent properties after multiple cycles of abrasion, blade scratching, tape-peeling, repeated deformation, a series of environmental tests and recycling. Based on its superhydrophobicity under oil, two highly efficient systems were developed for oil purification – stirring and inverted cone systems. Small water drops converge on the coated surface that was immersed in oil through velocity-controlled stirring, or designing an inverted cone superhydrophobic surface under oil to collect water drops spontaneously. This coating can be readily used for practical applications to make a durable superhydrophobic coating that functions either in air or oils
Influence of the Magnetic Coupling Process on the Advection Dominated Accretion Flows around Black Holes
A large-scale closed magnetic field can transfer angular momentum and energy
between a black hole (BH) and its surrounding accretion flow. We investigate
the effects of this magnetic coupling (MC) process on the dynamics of a hot
accretion flow (e.g., an advection dominated accretion flow, hereafter ADAF).
The energy and angular momentum fluxes transported by the magnetic field are
derived by an equivalent circuit approach. For a rapidly rotating BH, it is
found that the radial velocity and the electron temperature of the accretion
flow decrease, whereas the ion temperature and the surface density increase.
The significance of the MC effects depends on the value of the viscous
parameter \alpha. The effects are obvious for \alpha=0.3 but nearly ignorable
for \alpha=0.1. For a BH with specific angular momentum, a_*=0.9, and
\alpha=0.3, we find that for reasonable parameters the radiative efficiency of
a hot accretion flow can be increased by about 30%.Comment: 21 pages, 7 figures. Changed after the referee's suggestions.
Accepted for publication in the Astrophysical Journa
Turbulent convection: comparing the moment equations to numerical simulations
The non-local hydrodynamic moment equations for compressible convection are
compared to numerical simulations. Convective and radiative flux typically
deviate less than 20% from the 3D simulations, while mean thermodynamic
quantities are accurate to at least 2% for the cases we have investigated. The
moment equations are solved in minutes rather than days on standard
workstations. We conclude that this convection model has the potential to
considerably improve the modelling of convection zones in stellar envelopes and
cores, in particular of A and F stars.Comment: 10 pages (6 pages of text including figure captions + 4 figures),
Latex 2e with AAS Latex 5.0 macros, accepted for publication in ApJ
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Polarization and dispersion properties of elliptical hole golden spiral photonic crystal fiber
An elliptical air-hole golden spiral photonic crystal fiber (EGS-PCF) is analyzed with the full-vectorial finite element method. The air-holes in the EGS-PCF are arranged in a spiral pattern governed by the Golden Ratio, where the design has been inspired by the optimal arrangement of seeds found in nature. The EGS-PCF exhibits extremely high birefringence (∼0.022 at operating wavelength 1550 nm) which is particularly useful for generating a polarization stable supercontinuum (SC). The fiber can also be designed to have a Zero Dispersion Wavelength (ZDW) at a suitable wavelength for only one polarization and large negative dispersion for the other, leading to a single-polarization SC. In addition, the fiber dispersion can be designed to obtain ZDWs at 800 nm and 1064 nm simultaneously, which can facilitate broadband supercontinuum generation (SCG) through multi-wavelength pumping
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