Electrodiagnostic (EDx) studies play a key role in the investigation of suspected Guillain‐Barré syndrome (GBS), providing diagnostic and prognostic information. However, initial EDx findings may not ...fulfill the neurophysiological criteria for the disease. The aim of this study was to estimate the occurrence and characteristics of A‐waves and repeaters F‐waves (Freps), both late motor responses identical in latency and configuration, in early stages of GBS. We retrospectively analyzed the initial nerve conduction study (NCS) of 26 GBS patients performed within 10 days from symptom onset. The final subtype diagnosis was acute inflammatory demyelinating polyneuropathy (AIDP) in 16 patients (six met the criteria at the initial EDx study and 10 at follow‐up) and acute motor axonal neuropathy (AMAN) in 10 patients (six initially). Identical late responses were commonly found in the majority of nerves (84%). A‐waves were present in 59% and an increased frequency of Freps was calculated in 61% of the 105 studied nerves. A‐waves morphology (single or complex) could not distinguish between AIDP and AMAN. Nerves with normal NCS had a significantly higher frequency of A‐waves, either isolated or in combination with increased index total Freps, as compared to nerves with low compound muscle action potential (CMAP) amplitudes or conduction block. Our findings suggest that both late responses can be useful as early markers of conduction changes of various pathophysiology, being frequently present even prior to abnormalities of CMAP parameters.
The false targets generated by interrupted sampling repeater jamming (ISRJ) bring serious threats to radar target detection and imaging. Transmitted waveform design with joint processing has become a ...promising way to deal with them. In this letter, the ambiguity function (AF) of the integral power frequency modulated (PFM) waveform is derived. Meanwhile, the time-frequency characteristic of the ISRJ signal received by the radar is analyzed on the range-Doppler plane. In consideration of the range-Doppler coupling characteristic, an improved Doppler filtering processing method is proposed to suppress the jamming of false targets. Simulation results demonstrate that the selected PFM waveform with the proposed joint processing method can effectively suppress the false targets resulting from ISRJ.
Advances in single-photon creation, transmission, and detection suggest that sending quantum information over optical fibers may have losses low enough to be correctable using a quantum error ...correcting code (QECC). Such error-corrected communication is equivalent to a novel quantum repeater scheme, but crucial questions regarding implementation and system requirements remain open. Here we show that long-range entangled bit generation with rates approaching 108 entangled bits per second may be possible using a completely serialized protocol, in which photons are generated, entangled, and error corrected via sequential, one-way interactions with as few matter qubits as possible. Provided loss and error rates of the required elements are below the threshold for quantum error correction, this scheme demonstrates improved performance over transmission of single photons. We find improvement in entangled bit rates at large distances using this serial protocol and various QECCs. In particular, at a total distance of 500 km with fiber loss rates of 0.3 dB km−1, logical gate failure probabilities of 10−5, photon creation and measurement error rates of 10−5, and a gate speed of 80 ps, we find the maximum single repeater chain entangled bit rates of 51 Hz at a 20 m node spacing and 190 000 Hz at a 43 m node spacing for the 3 , 1 , 2 3 and 7 , 1 , 3 QECCs respectively as compared to a bare success rate of 1 × 10−140 Hz for single photon transmission.
In this paper, we argue that communication at the speed of light (CaSoL) through on-chip copper interconnects is possible in the near future based on giga-scale integration (GSI) technologies. A ...three-step algorithm is introduced to design the optimum buffers in such systems. HSPICE simulations show that a <inline-formula> <tex-math notation="LaTeX">1.3\times </tex-math></inline-formula> time of flight (<inline-formula> <tex-math notation="LaTeX">{T}_{\text {F}} </tex-math></inline-formula>) is reachable in 7-nm FinFET technology. It is also shown that such a design is by nature, robust, and immune to process variations and crosstalk noise.
This letter deals with a novel transmitted scheme for a multisubcarrier frequency multiple-input multiple-output (MIMO)-synthetic aperture radar (SAR) system, which aims at suppressing the intrapulse ...repeater mainlobe-jamming and immensely improving the dynamic range of the receiver. To this end, due to the multisubcarrier frequency transmission scheme, the mixed signal with true target signal and repeater jamming can be separated by a well-designed spatial-frequency filter. Thus, the range and direction of arrival (DOA) information is accurately estimated without interrupting the normal work of the radar. Furthermore, to further improve the orthogonality of transmitted waveform, the design of a phase-coded LFM waveform pair exhibiting both low cross correlation energy (CCE) and low peak to sidelobe ratios (PSLRs), is considered. Besides, to handle the resulting nondeterministic polynomial (NP) hard problem, an alternating direction multiplier method (ADMM) based optimization method is employed. Compared with the traditional jamming suppression method, the proposed method improves the degree of freedom (DOF) from the carrier frequency domain, and it has the capability to suppress the intrapulse repeater mainlobe-jamming. Finally, detailed simulation experiments are carried out to verify the practicability and effectiveness of the newly proposed transceiver schemes.
Teleportation of entanglement over 143 km Herbst, Thomas; Scheidl, Thomas; Fink, Matthias ...
Proceedings of the National Academy of Sciences - PNAS,
11/2015, Letnik:
112, Številka:
46
Journal Article
Recenzirano
Odprti dostop
As a direct consequence of the no-cloning theorem, the deterministic amplification as in classical communication is impossible for unknown quantum states. This calls for more advanced techniques in a ...future global quantum network, e.g., for cloud quantum computing. A unique solution is the teleportation of an entangled state, i.e., entanglement swapping, representing the central resource to relay entanglement between distant nodes. Together with entanglement purification and a quantum memory it constitutes a so-called quantum repeater. Since the aforementioned building blocks have been individually demonstrated in laboratory setups only, the applicability of the required technology in real-world scenarios remained to be proven. Here we present a free-space entanglement-swapping experiment between the Canary Islands of La Palma and Tenerife, verifying the presence of quantum entanglement between two previously independent photons separated by 143 km. We obtained an expectation value for the entanglement-witness operator, more than 6 SDs beyond the classical limit. By consecutive generation of the two required photon pairs and space-like separation of the relevant measurement events, we also showed the feasibility of the swapping protocol in a long-distance scenario, where the independence of the nodes is highly demanded. Because our results already allow for efficient implementation of entanglement purification, we anticipate our research to lay the ground for a fully fledged quantum repeater over a realistic high-loss and even turbulent quantum channel.
We analyze how the performance of a quantum-repeater network depends on the protocol employed to distribute entanglement, and we find that the choice of repeater-to-repeater link protocol has a ...profound impact on entanglement-distribution rate as a function of hardware parameters. We develop numerical simulations of quantum networks using different protocols, where the repeater hardware is modeled in terms of key performance parameters, such as photon generation rate and collection efficiency. These parameters are motivated by recent experimental demonstrations in quantum dots, trapped ions, and nitrogen-vacancy centers in diamond. We find that a quantum-dot repeater with the newest protocol ('MidpointSource') delivers the highest entanglement-distribution rate for typical cases where there is low probability of establishing entanglement per transmission, and in some cases the rate is orders of magnitude higher than other schemes. Our simulation tools can be used to evaluate communication protocols as part of designing a large-scale quantum network.
The optimal design of repeaters for current-mode (CM) nano-interconnects is conducted and compared with that for voltage-mode (VM) ones. Both Cu and carbon nanotube (CNT) nano-interconnects are ...considered and studied, with the contact resistance treated appropriately. In comparison with the VM ones, the CM nano-interconnects can not only demonstrate better electrical performance, but also require fewer repeaters, thereby saving more valuable chip area. In the delay-optimal repeater design of multi-walled CNT interconnects, for instance, the optimal number of repeaters can be reduced by 120% with the implementation of CM signalling scheme.
Display omitted
The topography of the Tibetan Plateau (TP) has shaped the paleoclimatic evolution of the Asian monsoon. However, the influence of the TP on the global climate, beyond the domain of ...the Asian monsoon, remains unclear. Here we show that the Pacific and Atlantic Oceans act as efficient repeaters that boost the global climatic impact of the TP. The simulations demonstrate that oceanic repeaters enable TP heating to induce a wide-ranging climate response across the globe. A 1 °C TP warming can result in a 0.73 °C temperature increase over North America. Oceanic repeaters exert their influence by enhancing the air-sea interaction-mediated horizontal heat and moisture transport, as well as relevant atmospheric circulation pathways including westerlies, stationary waves, and zonal-vertical cells. Air-sea interactions were further tied to local feedbacks, mainly the decreased air-sea latent heat flux from the weakening air-sea humidity difference and the increased shortwave radiation from sinking motion-induced cloud reduction over the North Pacific and Atlantic Oceans. Our findings highlight the crucial influence of TP heating variation on the current climate under a quasi-fixed topography, in contrast to topography change previously studied in paleoclimate evolution. Therefore, TP heating should be considered in research on global climate change.
PDF
