Intelligent Resource Allocation Scheme Using Reinforcement Learning for Efficient Data Transmission in VANET.

Vehicular ad hoc networks (VANETs) use multiple channels to communicate using wireless access in vehicular environment (WAVE) standards to provide a variety of vehicle-related applications. The current IEEE 802.11p WAVE communication channel structure is composed of one control channel (CCH) and several service channels (SCHs). SCHs are used for non-safety data transmission, while the CCH is used for broadcasting beacons, control, and safety. WAVE devices transmit data that alternate between CCHs and SCHs, and each channel is active for a duration called the CCH interval (CCHI) and SCH interval (SCHI), respectively. Currently, both intervals are fixed at 50 ms. However, fixed-length intervals cannot effectively respond to dynamically changing traffic loads. Additionally, when many vehicles are simultaneously using the limited channel resources for data transmission, the network performance significantly degrades due to numerous packet collisions. Herein, we propose an adaptive resource allocation technique for efficient data transmission. The technique dynamically adjusts the SCHI and CCHI to improve network performance. Moreover, to reduce data collisions and optimize the network's backoff distribution, the proposed scheme applies reinforcement learning (RL) to provide an intelligent channel access algorithm. The simulation results demonstrate that the proposed scheme can ensure high throughputs and low transmission delays.

Demonstration of Complete Information Trade-Off in Quantum Measurement.

While an information-disturbance trade-off in quantum measurement has been at the core of foundational quantum physics and constitutes a basis of secure quantum information processing, recently verified reversibility of a quantum measurement requires to refine it toward a complete version of information trade-off in quantum measurement. Here we experimentally demonstrate a trade-off relation among all information contents, i.e., information gain, disturbance, and reversibility in quantum measurement. By exploring quantum measurements applied on a photonic qutrit, we observe that the information of a quantum state is split into three distinct parts accounting for the extracted, disturbed, and reversible information. We verify that such different parts of information are in trade-off relations not only pairwise but also triplewise all at once, and find that the triplewise relation is tighter than any of the pairwise relations. Finally, we realize optimal quantum measurements that inherently preserve quantum information without loss of information, which offer wider applications in measurement-based quantum information processing.

Quantum State Learning via Single-Shot Measurements.

A novel machine-learning algorithm based on single-shot measurements, named single-shot measurement learning, is demonstrated achieving the theoretical optimal accuracy. The method is at least as efficient as existing tomographic schemes and computationally much less demanding. The merits are attributed to the inclusion of weighted randomness in the learning rule governing the exploration of diverse learning routes. These advantages are explored experimentally by a linear-optical setup that is designed to draw the fullest potential of the proposed method. The experimental results show an unprecedented high level of accuracy for qubit-state learning and reproduction exhibiting (nearly) optimal infidelity scaling, O(N^{-0.983}), for the number N of unknown state copies, down to <10^{-5} without any compensation for experimental nonidealities. Extension to high dimensions is discussed with simulation results.

A Novel Endogenous Damage Signal, CSF-2, Activates Multiple Beneficial Functions of Adipose Tissue-Derived Mesenchymal Stem Cells.

The major challenges of current mesenchymal stem cell (MSC)-based therapeutics are their low differentiation potential into specialized cell types and their homing ability to sites of injury. Therefore, many researchers have directed their efforts toward finding a novel stimulatory factor that can significantly enhance the therapeutic effects of MSCs. Colony-stimulating factor 2 (CSF-2) is previously known as a hematopoietic growth factor involved in the differentiation of various myeloid cells from hematopoietic progenitor cells. In addition to this canonical hematopoietic function, we identified for the first time that CSF-2 is actively secreted by stem cells, in response to various types of injuries, as an endogenous damage signal that promotes the therapeutic effects of MSCs by enhancing their multi-lineage differentiation and migratory capacities, possibly through its receptor CD116. Our results also revealed that CSF-2 exerts its stimulatory effects on MSCs via PI3K/Akt- and/or FAK/ERK1/2-signaling pathways. More importantly, we also found that MSCs stimulated with CSF-2 show markedly enhanced differentiation and migratory capacities and subsequent in vivo therapeutic effects in an endometrial ablation animal model. Collectively, our findings provide compelling evidence for a novel non-hematopoietic function of CSF-2 in promoting multiple beneficial functions of MSCs via a non-canonical mechanism as an endogenous damage signal.

Relative Entropy as a Measure of Difference between Hermitian and Non-Hermitian Systems.

We employ the relative entropy as a measure to quantify the difference of eigenmodes between Hermitian and non-Hermitian systems in elliptic optical microcavities. We have found that the average value of the relative entropy in the range of the collective Lamb shift is large, while that in the range of self-energy is small. Furthermore, the weak and strong interactions in the non-Hermitian system exhibit rather different behaviors in terms of the relative entropy, and thus it displays an obvious exchange of eigenmodes in the elliptic microcavity.

Stem Cell Secretome and Its Effect on Cellular Mechanisms Relevant to Wound Healing.

Stem cells introduced to site of injury primarily act via indirect paracrine effects rather than direct cell replacement of damaged cells. This gives rise to understanding the stem cell secretome. In this study, in vitro studies demonstrate that the secretome activates the PI3K/Akt or FAK/ERK1/2 signaling cascades and subsequently enhances the proliferative and migratory abilities of various types of skin cells, such as fibroblasts, keratinocytes, and vascular epithelial cells, ultimately accelerating wound contraction. Indeed, inhibition of these signaling pathways with synthetic inhibitors resulted in the disruption of secretome-induced beneficial effects on various skin cells. In addition, major components of the stem cell secretome (EGF, basic FGF, and HGF) may be responsible for the acceleration of wound contraction. Stimulatory effects of these three prominent factors on wound contraction are achieved through the upregulation of PI3K/Akt or FAK/ERK1/2 activity. Overall, we lay the rationale for using the stem cell secretome in promoting wound contraction. In vivo wound healing studies are warranted to test the significance of our in vitro findings.

A Cooperative Communication Protocol for QoS Provisioning in IEEE 802.11p/Wave Vehicular Networks.

Vehicular ad hoc networks (VANETs) provide information and entertainment to drivers for safe and enjoyable driving. Wireless Access in Vehicular Environments (WAVE) is designed for VANETs to provide services efficiently. In particular, infotainment services are crucial to leverage market penetration and deployment costs of the WAVE standard. However, a low presence of infrastructure results in a shadow zone on the road and a link disconnection. The link disconnection is an obstacle to providing safety and infotainment services and becomes an obstacle to the deployment of the WAVE standard. In this paper, we propose a cooperative communication protocol to reduce performance degradation due to frequent link disconnection in the road environment. The proposed protocol provides contention-free data delivery by the coordination of roadside units (RSUs) and can provide the network QoS. The proposed protocol is shown to enhance throughput and delay through the simulation.

High resolution three-dimensional flash LIDAR system using a polarization modulating Pockels cell and a micro-polarizer CCD camera.

An innovative flash LIDAR (light detection and ranging) system with high spatial resolution and high range precision is proposed in this paper. The proposed system consists of a polarization modulating Pockels cell (PMPC) and a micro-polarizer CCD camera (MCCD). The Pockels cell changes its polarization state with respect to time after a laser pulse is emitted from the system. The polarization state of the laser-return pulse depends on the arrival time. The MCCD measures the intensity of the returning laser pulse to calculate the polarization state, which gives the range. A spatial resolution and range precision of 0.12 mrad and 5.2 mm at 16 m were obtained, respectively, in this experiment.

Role of Carbohydrate response element-binding protein in mediating dexamethasone-induced glucose transporter 5 expression in Caco-2BBE cells and during the developmental phase in mice.

Glucose transporter 5 (GLUT5), the main fructose transporter in mammals, is primarily responsible for absorbing dietary fructose in the small intestine. The expression of this intestinal gene significantly increases in response to developmental and dietary cues that reach the glucocorticoid receptor and carbohydrate response element-binding protein (ChREBP), respectively. Our study demonstrates that ChREBP is involved in the dexamethasone (Dex)-induced expression of GLUT5 in Caco-2BBE cells and the small intestine of both wild-type and ChREBP-knockout mice. Dex, a glucocorticoid, demonstrated an increase in GLUT5 mRNA levels in a dose- and time-dependent manner. While the overexpression of ChREBP moderately increased GLUT5 expression, its synergistic increase in the presence of Dex was noteworthy, whereas the suppression of ChREBP significantly reduced Dex-induced GLUT5 expression. Dex did not increase ChREBP protein levels but facilitated its nuclear translocation, thereby increasing the activity of the GLUT5 promoter. In vivo experiments conducted on 14-day-old mice pups treated with Dex for three days revealed that only wild-type mice (not ChREBP-knockout mice) exhibited Dex-mediated Glut5 gene induction, which further supports the role of ChREBP in regulating GLUT5 expression. Collectively, our results provide insights into the molecular mechanisms involved in the regulation of GLUT5 expression in response to developmental and dietary signals mediated by glucocorticoids and ChREBP. General significance: The transcription factor ChREBP is important for Dex-mediated Glut5 gene expression in the small intestine.

Why Have the Republic of Korea, Taiwan, and Singapore Coped Well with COVID-19 and What Are the Lessons Learned from Their Experiences?

This study investigated how three Asian countries-Republic of Korea (ROK), Republic of China (Taiwan), and Singapore-considered as standouts, responded to the coronavirus disease 2019 (COVID-19) in terms of governance system, health sector innovation, and social distancing to draw lessons that other countries can learn from. The countries were commonly in success of the response in early stage of the pandemic thanks to their effective and efficient strategies paired with advanced information and communications technology (ICT). Consequently, the three jurisdictions reported lower confirmed cases as well as fatality rate of the infectious disease compared to other high-income countries. In addition, the countries' previous experiences with other pandemics, including influenza A, Middle East respiratory syndrome, and severe acute respiratory syndrome, enabled them to establish resilient public health systems and gain public acceptance to governmental control or surveillance during national infectious disease-related crises outbreaks. Advanced ICT infrastructure and digital technology were used as effective tools for testing, tracing, and treatment of the pandemic in collaboration with the private sector as a crucial player. The ROK, Taiwan, and Singapore adopted different strategies between containment and mitigation policy to flatten the epidemic curves effectively according to their own situation and judgement. Despite the exemplary aspect of the three nations in coping with the COVID-19 pandemic, a few limitations were also observed in terms of vaccination and unequal consequences of the pandemic among people. These should be further discussed in order to be prepared for future pandemics.

Loophole-free bell test for continuous variables via wave and particle correlations.

We derive two classes of multimode Bell inequalities under local realistic assumptions, which are violated only by the entangled states negative under partial transposition in accordance with the Peres conjecture. Remarkably, the failure of local realism can be manifested by exploiting wave and particle correlations of readily accessible continuous-variable states, with very large violation of inequalities insensitive to detector efficiency, which makes a strong case for a loophole-free test.

High resolution interferometer with multiple-pass optical configuration.

An interferometer having fourteen times higher resolution than a conventional single-pass interferometer has been developed by making multiple-pass optical path. To embody the multiple-pass optical configuration, a two-dimensional corner cube array block was designed, and its symmetric structure minimized the measurement error. The effect from the alignment error and the imperfection of corner cube is calculated as picometer level. An experiment proves that the suggested interferometer has about 45 nm of optical resolution and its nonlinearity is about 0.5 nm in peak-to-valley.

High speed phase shifting interferometry using injection locking of the laser frequency to the resonant modes of a confocal Fabry-Perot cavity.

We present a high speed phase shifting interferometer which utilizes the self injection locking of a frequency tunable laser diode. By using a confocal Fabry-Perot cavity made of ultra low expansion glass, and linearly modulating the laser diode current, the laser frequency could be injection locked to the resonant modes of the Fabry-Perot cavity consecutively. It provided equal phase steps to the interferograms which are ideal to be analyzed by the Carré algorithm. The phase step error was evaluated to be about 3 MHz which corresponds to 0.2 nm in length measurement. With this technique, profile measurements are insensitive to external vibration since four 640x480 pixels images can be acquired within 4 ms. Difference of two profile measurements, each made with and without vibration isolation, respectively, was evaluated to be 0.5 nm (rms).

Logical measurement-based quantum computation in circuit-QED.

We propose a new scheme of measurement-based quantum computation (MBQC) using an error-correcting code against photon-loss in circuit quantum electrodynamics. We describe a specific protocol of logical single-qubit gates given by sequential cavity measurements for logical MBQC and a generalised Schrödinger cat state is used for a continuous-variable (CV) logical qubit captured in a microwave cavity. To apply an error-correcting scheme on the logical qubit, we utilise a d-dimensional quantum system called a qudit. It is assumed that a three CV-qudit entangled state is initially prepared in three jointed cavities and the microwave qudit states are individually controlled, operated, and measured through a readout resonator coupled with an ancillary superconducting qubit. We then examine a practical approach of how to create the CV-qudit cluster state via a cross-Kerr interaction induced by intermediary superconducting qubits between neighbouring cavities under the Jaynes-Cummings Hamiltonian. This approach could be scalable for building 2D logical cluster states and therefore will pave a new pathway of logical MBQC in superconducting circuits toward fault-tolerant quantum computing.

A compact system for simultaneous measurement of linear and angular displacements of nano-stages.

We report on a novel compact interferometery system for measuring parasitic motions of a precision stage. It is a combination of a Michelson interferometer with an auto-collimator, of which full physical dimension is mere 70 mm x80 mm x35 mm (WxLxH) including optical components, photo-detectors, and electronic circuits. Since the beams, which measure displacement and angle, can be directed at the same position on the moving mirror, the system is applicable for testing small nano-stages where commercial interferometers are not able to be used. And thus, errors from nano-scale deformation of the moving mirror can be minimized. We find that the residual errors of linear and angular motion measurements are 2.5 nm in peak-to-peak and 0.2'', respectively.

Noncollinear correlated photon pair source in the 1550 nm telecommunication band.

We present a source of noncollinear correlated photon pairs in the standard 1550 nm telecommunication band. They are generated by a spontaneous parametric down-conversion process and emitted in a cone because of type-I noncollinear phase matching. Within the band, the source gives a completely flexible choice of the frequencies of the photon pairs, and correlation properties related to spatial momentum as well as energy and time can easily be utilized.We characterize the source by measuring the spatial intensity distribution of the down-converted light and by performing coincidence counting.

Gaussian private quantum channel with squeezed coherent states.

While the objective of conventional quantum key distribution (QKD) is to secretly generate and share the classical bits concealed in the form of maximally mixed quantum states, that of private quantum channel (PQC) is to secretly transmit individual quantum states concealed in the form of maximally mixed states using shared one-time pad and it is called Gaussian private quantum channel (GPQC) when the scheme is in the regime of continuous variables. We propose a GPQC enhanced with squeezed coherent states (GPQCwSC), which is a generalization of GPQC with coherent states only (GPQCo) [Phys. Rev. A 72, 042313 (2005)]. We show that GPQCwSC beats the GPQCo for the upper bound on accessible information. As a subsidiary example, it is shown that the squeezed states take an advantage over the coherent states against a beam splitting attack in a continuous variable QKD. It is also shown that a squeezing operation can be approximated as a superposition of two different displacement operations in the small squeezing regime.