1,507 research outputs found
Atomistic pseudopotential calculations of the optical properties of InAs/InP self-assembled quantum dots
We present a comprehensive study of the optical properties of InAs/InP
self-assembled quantum dots (QDs) using an empirical pseudopotential method and
configuration interaction treatment of the many-particle effects. The results
are compared to those of InAs/GaAs QDs. The main results are: (i) The alignment
of emission lines of neutral exciton, charged exciton and biexciton in InAs/InP
QDs is quite different from that in InAs/GaAs QDs. (ii) The hidden correlation
in InAs/InP QDs is 0.7 - 0.9 meV, smaller than that in InAs/GaAs QDs. (iii) The
radiative lifetimes of neutral exciton, charged exciton and biexciton in
InAs/InP QDs are about twice longer than those in InAs/GaAs QDs. (v) The phase
diagrams of few electrons and holes in InAs/InP QDs differ greatly from those
in InAs/GaAs QDs. The filling orders of electrons and holes are shown to obey
the Hund's rule and Aufbau principle, and therefore the photoluminescence
spectra of highly charged excitons are very different from those of InAs/GaAs
QDs.Comment: 10 pages, 11 figure
Static Quark Potential and the Renormalized Anisotropy on Tadpole Improved Anisotropic Lattices
Static quark potential is studied using a tadpole improved gauge lattice
action. The scale is set using the potential for a wide range of bare
parameters.
The renormalized anisotropy of the lattice is also measured.Comment: 11 pages, 5 figures, accepted for publication in Int. J. Mod. Phys.
A New Mouse Model of Aortic Aneurysm Induced by Deoxycorticosterone Acetate or Aldosterone in the Presence of High Salt
The renin-angiotensin-aldosterone system (RAAS) is implicated in the etiologies of many cardiovascular diseases, including abdominal aortic aneurysm (AAA) and thoracic aortic aneurysm (TAA). In particular, the infusion of angiotensin II (Ang II) in hyperlipidemia mice to induce AAA and TAA has been extensively used in the field, suggesting a critical role of Ang II in aortic aneurysm. In contrast, whether aldosterone (Aldo), a downstream effector of Ang II, is involved in aortic aneurysm is unknown. Here, we describe a new mouse model of AAA and TAA induced by subcutaneous implantation of deoxycorticosterone acetate (DOCA) pellets or infusion of Aldo using osmotic pumps to 10-month-old C57BL/6 male mice in the presence of high salt. The DOCA- or Aldo-salt-induced aortic aneurysm is dependent upon mineralocorticoid receptor activation but independent of Ang II and hypertension and exhibits several unique features that mimic human aortic aneurysm. This review aims to discuss the common animal models of AAA, TAA, and aortic dissection currently studied in the world with the most focus on the DOCA- or Aldo-salt mouse model of aortic aneurysm
Temperature Dependent Empirical Pseudopotential Theory For Self-Assembled Quantum Dots
We develop a temperature dependent empirical pseudopotential theory to study
the electronic and optical properties of self-assembled quantum dots (QDs) at
finite temperature. The theory takes the effects of both lattice expansion and
lattice vibration into account. We apply the theory to the InAs/GaAs QDs. For
the unstrained InAs/GaAs heterostructure, the conduction band offset increases
whereas the valence band offset decreases with increasing of the temperature,
and there is a type-I to type-II transition at approximately 135 K. Yet, for
InAs/GaAs QDs, the holes are still localized in the QDs even at room
temperature, because the large lattice mismatch between InAs and GaAs greatly
enhances the valence band offset. The single particle energy levels in the QDs
show strong temperature dependence due to the change of confinement potentials.
Because of the changes of the band offsets, the electron wave functions
confined in QDs increase by about 1 - 5%, whereas the hole wave functions
decrease by about 30 - 40% when the temperature increases from 0 to 300 K. The
calculated recombination energies of exciton, biexciton and charged excitons
show red shifts with increasing of the temperature, which are in excellent
agreement with available experimental data
Dissipationless Layertronics in Axion Insulator
Surface electrons in axion insulators are endowed with a topological layer
degree of freedom followed by exotic transport phenomena, e.g., the layer Hall
effect [Gao et al., Nature 595, 521 (2021)]. Here, we propose that such a layer
degree of freedom can be manipulated in a dissipationless way based on the
antiferromagnetic with tailored domain structure. This makes
a versatile platform to exploit the "layertronics" to encode,
process, and store information. Importantly, the layer filter, layer valve, and
layer reverser devices can be achieved using the layer-locked chiral domain
wall modes. The dissipationless nature of the domain wall modes makes the
performance of the layertronic-devices superior to those in spintronics and
valleytronics. Specifically, the layer reverser, a layer version of Datta-Das
transistor, also fills up the blank in designing the valley reverser in
valleytronics. Our work sheds light on constructing new generation electronic
devices with high performance and low energy consumption in the framework of
layertronics.Comment: 7 pages, 4 figures (+Supplementary Materials: 5 pages, 6 figures
Telemetric Blood Pressure Assessment in Angiotensin II-Infused ApoE\u3csup\u3e-/-\u3c/sup\u3e Mice: 28 Day Natural History and Comparison to Tail-Cuff Measurements
Abdominal aortic aneurysm (AAA) is a disease of the aortic wall, which can progress to catastrophic rupture. Assessment of mechanical characteristics of AAA, such as aortic distensibility, may provide important insights to help identify at-risk patients and understand disease progression. While the majority of studies on this topic have focused on retrospective patient data, recent studies have used mouse models of AAA to prospectively evaluate the evolution of aortic mechanics. Quantification of aortic distensibility requires accurate measurement of arterial blood pressure, particularly pulse pressure, which is challenging to perform accurately in murine models. We hypothesized that volume/pressure tail-cuff measurements of arterial pulse pressure in anesthetized mice would have sufficient accuracy to enable calculations of aortic distensibility with minimal error. Telemetry devices and osmotic mini-pumps filled with saline or angiotensin-II were surgically implanted in male apolipoprotein-E deficient (ApoE-/-) mice. Blood pressure in the aortic arch was measured continuously via telemetry. In addition, simultaneous blood pressure measurements with a volume/pressure tail-cuff system were performed under anesthesia at specific intervals to assess agreement between techniques. Compared to controls, mice infused with angiotensin-II had an overall statistically significant increase in systolic pressure, with no overall difference in pulse pressure; however, pulse pressure did increase significantly with time. Systolic measurements agreed well between telemetry and tail-cuff (coefficient of variation = 10%), but agreement of pulse pressure was weak (20%). In fact, group-averaged pulse pressure from telemetry was a better predictor of a subject\u27s pulse pressure on a given day than a simultaneous tail-cuff measurement. Furthermore, these approximations introduced acceptable errors (15.1 ± 12.8%) into the calculation of aortic distensibility. Contrary to our hypothesis, we conclude that tail-cuff measures of arterial pulse pressure have limited accuracy. Future studies of aneurysm mechanics using the ApoE-/-/angiotensin-II model would be better in assuming pulse pressure profiles consistent with our telemetry findings instead of attempting to measure pulse pressure in individual mice
Many-body Landau-Zener Transition in Cold Atom Double Well Optical Lattices
Ultra-cold atoms in optical lattices provide an ideal platform for exploring
many-body physics of a large system arising from the coupling among a series of
small identical systems whose few-body dynamics is exactly solvable. Using
Landau-Zener (LZ) transition of bosonic atoms in double well optical lattices
as an experimentally realizable model, we investigate such few to many body
route by exploring the relation and difference between the small few-body (in
one double well) and the large many-body (in double well lattice)
non-equilibrium dynamics of cold atoms in optical lattices. We find the
many-body coupling between double wells greatly enhances the LZ transition
probability. The many-body dynamics in the double well lattice shares both
similarity and difference from the few-body dynamics in one and two double
wells. The sign of the on-site interaction plays a significant role on the
many-body LZ transition. Various experimental signatures of the many-body LZ
transition, including atom density, momentum distribution, and density-density
correlation, are obtained.Comment: 7 pages, 6 figure
Demonstration of Adiabatic Variational Quantum Computing with a Superconducting Quantum Coprocessor
Adiabatic quantum computing enables the preparation of many-body ground
states. This is key for applications in chemistry, materials science, and
beyond. Realisation poses major experimental challenges: Direct analog
implementation requires complex Hamiltonian engineering, while the digitised
version needs deep quantum gate circuits. To bypass these obstacles, we suggest
an adiabatic variational hybrid algorithm, which employs short quantum circuits
and provides a systematic quantum adiabatic optimisation of the circuit
parameters. The quantum adiabatic theorem promises not only the ground state
but also that the excited eigenstates can be found. We report the first
experimental demonstration that many-body eigenstates can be efficiently
prepared by an adiabatic variational algorithm assisted with a multi-qubit
superconducting coprocessor. We track the real-time evolution of the ground and
exited states of transverse-field Ising spins with a fidelity up that can reach
about 99%.Comment: 12 pages, 4 figure
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