15,406 research outputs found
Finite temperature Casimir pistons for electromagnetic field with mixed boundary conditions and its classical limit
In this paper, the finite temperature Casimir force acting on a
two-dimensional Casimir piston due to electromagnetic field is computed. It was
found that if mixed boundary conditions are assumed on the piston and its
opposite wall, then the Casimir force always tends to restore the piston
towards the equilibrium position, regardless of the boundary conditions assumed
on the walls transverse to the piston. In contrary, if pure boundary conditions
are assumed on the piston and the opposite wall, then the Casimir force always
tend to pull the piston towards the closer wall and away from the equilibrium
position. The nature of the force is not affected by temperature. However, in
the high temperature regime, the magnitude of the Casimir force grows linearly
with respect to temperature. This shows that the Casimir effect has a classical
limit as has been observed in other literatures.Comment: 14 pages, 3 figures, accepted by Journal of Physics
Method for distortion correction of multi-layered surface reconstruction using time-gated wavefront sensing approach
In order to estimate the multi-layer surface profile and to detect the inter-layer surfaces defects, gated wavefront sensing approach has been proposed in the previous works [1, 2]. However, the proposed methodology measures the wavefront that has been distorted by its prior surfaces (reflected wavefront) or post surfaces (transmitted wavefront). Analysis has to be performed to estimate the multi-layer wavefront sensing by taking into consideration the multi-layer surfaces condition. For reflected wavefront, the bottom layer(s) wavefront is (are) being distorted twice via separate interface points while traveling back to the lenslet arrays through our observation for the slope and phase measurement. The subsequent reconstructed surfaces are not accurate and corrected. Thus, a discrete layer correction technique for the surface reconstruction has been proposed to enhance the reconstruction accuracy by using the upper/top layerâs wavefront information. This paper discusses on the case of 2-layer system, where the reflected wavefront from the bottom layer has been distorted and its surface reconstruction has been corrected. The results show that the distortion is significant and the correction is deemed necessary for industrial application such as in wafer warpage inter-layer profile estimation
Hamiltonian Analysis of Lagrange Multiplier Modified Gravity
We develop Hamiltonian formalism for Lagrange Multiplier Modified Gravity. We
further calculate the Poisson brackets between constraints and we show that
they coincide with the algebra of constraints in Hamiltonian formulation of
General Relativity.Comment: 15 pages, references adde
Vitrification within a nanoliter volume : oocyte and embryo cryopreservation within a 3D photopolymerized device
Open Access funding enabled and organized by CAUL and its Member ï»żInstitutions. KRD is supported by a Mid-Career Fellowship from the Hospital Research Foundation (C-MCF-58â2019). KD acknowledges funding from the UK Engineering and Physical Sciences Research Council (grants EP/P030017/1). This study was funded by the Australian Research Council (ARC) Centre of Excellence for Nanoscale BioPhotonics (CE140100003).Purpose Vitrification permits long-term banking of oocytes and embryos. It is a technically challenging procedure requiring direct handling and movement of cells between potentially cytotoxic cryoprotectant solutions. Variation in adherence to timing, and ability to trace cells during the procedure, affects survival post-warming. We hypothesized that minimizing direct handling will simplify the procedure and improve traceability. To address this, we present a novel photopolymerized device that houses the sample during vitrification. Methods The fabricated device consisted of two components: the Pod and Garage. Single mouse oocytes or embryos were housed in a Pod, with multiple Pods docked into a Garage. The suitability of the device for cryogenic application was assessed by repeated vitrification and warming cycles. Oocytes or early blastocyst-stage embryos were vitrified either using standard practice or within Pods and a Garage and compared to non-vitrified control groups. Post-warming, we assessed survival rate, oocyte developmental potential (fertilization and subsequent development) and metabolism (autofluorescence). Results Vitrification within the device occurred withinâ~â3 nL of cryoprotectant: this volume beingâ~â1000-fold lower than standard vitrification. Compared to standard practice, vitrification and warming within our device showed no differences in viability, developmental competency, or metabolism for oocytes and embryos. The device housed the sample during processing, which improved traceability and minimized handling. Interestingly, vitrification-warming itself, altered oocyte and embryo metabolism. Conclusion The Pod and Garage system minimized the volume of cryoprotectant at vitrificationâbyâ~â1000-foldâimproved traceability and reduced direct handling of the sample. This is a major step in simplifying the procedure.Publisher PDFPeer reviewe
Relativistic quantum effects of Dirac particles simulated by ultracold atoms
Quantum simulation is a powerful tool to study a variety of problems in
physics, ranging from high-energy physics to condensed-matter physics. In this
article, we review the recent theoretical and experimental progress in quantum
simulation of Dirac equation with tunable parameters by using ultracold neutral
atoms trapped in optical lattices or subject to light-induced synthetic gauge
fields. The effective theories for the quasiparticles become relativistic under
certain conditions in these systems, making them ideal platforms for studying
the exotic relativistic effects. We focus on the realization of one, two, and
three dimensional Dirac equations as well as the detection of some relativistic
effects, including particularly the well-known Zitterbewegung effect and Klein
tunneling. The realization of quantum anomalous Hall effects is also briefly
discussed.Comment: 22 pages, review article in Frontiers of Physics: Proceedings on
Quantum Dynamics of Ultracold Atom
Effect of grain and secondary phase morphologies in the mechanical and damping behavior of Al7075 alloys
The present study evaluates the role of the microstructure in the static and dynamic mechanical behavior of as-cast Al7075 alloy promoted by ultrasonic treatment (US) during solidification. The characterization of samples revealed that US treatment promoted grain and intermetallics refinement, changed the shape of the intermetallic phases (equilibrium phases of soluble M and/or T (Al, Cu, Mg, Zn) and their insoluble Al-Cu-Fe compounds) and lead to their uniform distribution along the grain boundaries. Consequently, the mechanical properties and damping capacity above critical strain values were enhanced by comparison with values obtained for castings produced without US vibration. This results suggest that the grain and secondary phases refinement by US can be a promising solution to process materials to obtain high damping and high strength characteristics.This research was supported by FEDER/COMPETE funds and by national funds through FCT - Portuguese Foundation for Science and Technology and was developed on the aim of the research Post-Doctoral grant SFRH/BPD/76680/2011. Also, this work has been supported by the FCT in the scope of the project: UID/EEA/04436/2013.info:eu-repo/semantics/publishedVersio
How precisely can we reduce the three-flavor neutrino oscillation to the two-flavor one only from (\delta m^2_{12})/(\delta m^2_{13}) <~ 1/15 ?
We derive the reduction formula, which expresses the survival rate for the
three-flavor neutrino oscillation by the two-flavor one, to the next-to-leading
order in case there is one resonance due to the matter effect. We numerically
find that the next-to-leading reduction formula is extremely accurate and the
improvement is relevant for the precision test of solar neutrino oscillation
and the indirect measurment of CP violation in the leptonic sector. We also
derive the reduction formula, which is slightly different from that previously
obtained, in case there are two resonances. We numerically verify that this
reduction formula is quite accurate and is valid for wider parameter region
than the previously obtained ones are.Comment: 28pages, 8figures, revtex4. to appear in PR
Search for charmonium and charmonium-like states in \Upsilon(2S) radiative decays
Using a sample of 158 million \Upsilon(2S) events collected with the Belle
detector, charmonium and charmonium-like states with even charge parity are
searched for in \Upsilon(2S) radiative decays. No significant \chi_{cJ} or
\eta_c signal is observed and the following upper limits at 90% confidence
level (C.L.) are obtained: BR(\Upsilon(2S)\to \gamma \chi_{c0})< 1.0 \times
10^{-4}, BR(\Upsilon(2S) \to \gamma \chi_{c1})<3.6 \times 10^{-6},
BR(\Upsilon(2S) \to \gamma \chi_{c2})<1.5 \times 10^{-5}, and BR(\Upsilon(2S)
\to \gamma \eta_c)< 2.7 \times 10^{-5}. No significant signal of any
charmonium-like state is observed, and we obtain the limits \BR(\Upsilon(2S)\to
\gamma X(3872))\times\BR(X(3872)\to\pi^+\pi^-J/\psi)< 0.8 \times 10^{-6},
BR(\Upsilon(2S) \to \gamma X(3872))\times BR(X(3872)\to\pi^+\pi^-\pi^0 J/\psi)<
2.4\times 10^{-6}, BR(\Upsilon(2S) \to \gamma X(3915))\times
BR(X(3915)\to\omega J/\psi)< 2.8\times 10^{-6}, BR(\Upsilon(2S) \to \gamma
Y(4140))\times BR(Y(4140)\to\phi J/\psi)) < 1.2\times 10^{-6}, and
BR(\Upsilon(2S) \to \gamma X(4350))\times BR(X(4350)\to\phi J/\psi))< 1.3\times
10^{-6} at 90% C.L.Comment: 7 pages, 6 figures, 1 tabl
Search for double charmonium decays of the P-wave spin-triplet bottomonium states
Using a sample of 158 million events collected with the Belle
detector, we search for the first time for double charmonium decays of the
-wave spin-triplet bottomonium states (,
\chi_{bJ} \to \jpsi \jpsi, \jpsi \psp, \psp \psp for J=0, 1, and 2). No
significant signal is observed in the double charmonium mass
spectra, and we obtain the following upper limits, \BR(\chi_{bJ} \to \jpsi
\jpsi)<7.1\times 10^{-5}, , ,
\BR(\chi_{bJ} \to \jpsi \psp)<1.2\times 10^{-4}, ,
, \BR(\chi_{bJ} \to \psp \psp)<3.1\times 10^{-5},
, for J=0, 1, and 2, respectively, at
the 90% confidence level. These limits are significantly lower than the central
values (with uncertainties of 50% to 70%) predicted using the light cone
formalism but are consistent with calculations using the NRQCD factorization
approach.Comment: 7 pages, 4 figures, 1 tabl
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