4,038 research outputs found
Interface control of ferroelectricity in LaNiO3-BaTiO3 superlattices
LaNiO-BaTiO superlattices with different types of interfaces are
studied from first-principles density-functional theory. It is revealed that
the ferroelectricity in the superlattice with (NiO)/(BaO)
interfaces is enhanced from that of the superlattice with
(LaO)/(TiO) interfaces. The origin lies at the polar discontinuity
at the interface, which makes the holes localized within the
(NiO)/(BaO) interface, but drives a penetration of electrons into
BaTiO component near (LaO)/(TiO) interface. Our calculations
demonstrate an effective avenue to the robust ferroelectricity in BaTiO
ultrathin films.Comment: 14 pages, 6 figure
RvMDM and lepton flavor violation
A model relating radiative seesaw and minimal dark matter mass scales without beyond the standard model (SM) gauge symmetry (RνMDM) is constructed. In addition to the SM particles, the RνMDM contains, a Majorana fermion multiplet N _R and scalar multiplet χ that transform respectively as (1, 5, 0) and (1,6,−1/2) under the SM gauge group SU(3)_C × SU(2) _L × U(1)_Y . The neutral component N_R^0 plays the role of dark matter with a mass in the range of 9 to 10 TeV. This scale also sets the lower limit for the scale for the heavy degrees of freedom in N_R and χ which generate light neutrino masses through the radiative seesaw mechanism. The model predicts an N_R^0-nucleus scattering cross section that would be accessible with future dark matter direct detection searches as well as observable effects in present and searches for charged lepton flavor violating processes, such as l_i → l_j γ and μ − e conversion
Approximability of the Eight-Vertex Model
We initiate a study of the classification of approximation complexity of the eight-vertex model defined over 4-regular graphs. The eight-vertex model, together with its special case the six-vertex model, is one of the most extensively studied models in statistical physics, and can be stated as a problem of counting weighted orientations in graph theory. Our result concerns the approximability of the partition function on all 4-regular graphs, classified according to the parameters of the model. Our complexity results conform to the phase transition phenomenon from physics.
We introduce a quantum decomposition of the eight-vertex model and prove a set of closure properties in various regions of the parameter space. Furthermore, we show that there are extra closure properties on 4-regular planar graphs. These regions of the parameter space are concordant with the phase transition threshold. Using these closure properties, we derive polynomial time approximation algorithms via Markov chain Monte Carlo. We also show that the eight-vertex model is NP-hard to approximate on the other side of the phase transition threshold
Testing the coupling of dark radiations in light of the Hubble tension
Self-interacting dark radiations (SIdr) can have significant implications in
the evolution of the universe, affecting the cosmic microwave background (CMB)
and the clustering of large-scale structures. In this work, we analyze the
implications of SIdr on the CMB power spectrum and explore its potential in
resolving the Hubble tension. SIdr exhibits two distinct behaviors based on the
interacting strength: strongly self-coupled and medium self-coupled. These
behaviors are evident in the analysis of CMB data. According to Planck data,
the dark radiation component consists of both free-streaming neutrinos and
possible SIdr. The total contribution from these components yields relativistic
species with . In the framework of universal coupling
between dark radiations, a consistent value of is obtained. Additionally, this coupling results in
an increase in the Hubble constant () to . However, when considering the number of free-streaming
neutrinos as a parameter, the existence of SIdr is not supported. This makes
its fraction in radiation to be . Although the
Hubble constant is still enhanced, it comes at the expense of a higher . Our findings reveal that the ACT and SPT data provide
support for the presence of SIdr, particularly when considering a variable
number of free-streaming species. In this case, SIdr accounts for approximately
12.7\% of the total radiation content. However, it is important to note that
relying solely on SIdr is insufficient to completely resolve the Hubble
tension. Finally, we investigate the constraints on SIdr imposed by future
experiments, which improve the limits on scaled interacting strength
by a factor of 4.5 compared to the current
constraints.Comment: 23 pages, 8 figures, 4 table
Guidance Law Design for a Class of Dual-Spin Mortars
To minimize the cost and maximize the ease of use, a class of dual-spin mortars is designed which only rely on GPS receiver and geomagnetic measurements. However, there are some problems to be solved when the range is small, such as low correction authority and trajectory bending. Guidance law design for this mortar is detailed. Different guidance laws were designed for the ascending and descending segments, respectively. By taking variable parameter guidance law in the vertical plane and using compensation in the lateral plane, the problems mentioned above were resolved. Roll angle resolving algorithms with geomagnetic measurements were demonstrated and the experiment results proved to be effective. In order to verify the effectiveness, Seven-Degrees-of-Freedom (7-DOF) rigid ballistic model were established and hardware in the loop simulation was introduced. After the transform function of the actuator was obtained, the control model of the shell was improved. The results of the Monte Carlo simulation demonstrate that the guidance law is suitable and the mortar can be effectively controlled
Novel matrine derivative MD-1 attenuates hepatic fibrosis by inhibiting EGFR activation of hepatic stellate cells
Advances in Atomic Time Scale imaging with a Fine Intrinsic Spatial Resolution
Atomic time scale imaging, opening a new era for studying dynamics in
microcosmos, is presently attracting immense research interesting on the global
level due to its powerful ability. On the atom level, physics, chemistry, and
biology are identical for researching atom motion and atomic state change. The
light possesses twoness, the information carrier and the research resource. The
most fundamental principle of this imaging is that light records the event
modulated light field by itself, so called all optical imaging. This paper can
answer what is the essential standard to develop and evaluate atomic time scale
imaging, what is the optimal imaging system, and what are the typical
techniques to implement this imaging, up to now. At present, the best record in
the experiment, made by multistage optical parametric amplification (MOPA), is
realizing 50 fs resolved optical imaging with a spatial resolution of ~83 lp/mm
at an effective framing rate of 10^13 fps for recording an ultrafast optical
lattice with its rotating speed up to 10^13 rad/s
Vremenski razlučeni fotoluminescentni spektri legure (AlxGa1−x)0.51In0.49P (x = 0.29)
Measurements of time-resolved photoluminescence (TRPL) spectra were made in a study of the optical properties of partially ordered quaternary (AlxGa1-x)0.51In0.49P (x=0.29) alloy. Both excitation-wavelength dependence of lifetime and excitation-intensity dependence of lifetime show a wide distribution of carriers. In TRPL spectra measured at 300 K, a blue-shift of photoluminescence (PL) peaks in (AlxGa1-x)0.51In0.49P is observed. The phenomenon is in agreement with the Z-shaped temperature dependence of the PL peak. Possible origins of the blue-shift and Z-shaped behaviour of PL peak are presented.Načinili smo vremenski-razlučena (VR) mjerenja fotoluminescentnih (FL) spektara radi istraživanja optičkih svojstava djelomično sređene četverokomponentne legure (AlxGa1−x)0.51In0.49P (x = 0.29). Obje ovisnosti vremena života, uzbuda – valna duljina i uzbuda – intenzitet pokazuju široku raspodjelu nositelja. VR FL spektri (AlxGa1−x)0.51In0.49P na 300 K pokazuju plavi pomak fotoluminescentnih linija. Ta je pojava u skladu s temperaturnom ovisnošću FL vrha u vidu slova Z. Raspravljaju se mogući uzroci plavog pomaka i Z-ovisnosti FL vrha
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