Analysis on tailed distributed arithmetic codes for uniform binary sources

Distributed Arithmetic Coding (DAC) is a variant of Arithmetic Coding (AC) that can realise Slepian-Wolf Coding (SWC) in a nonlinear way. In the previous work, we defined Codebook Cardinality Spectrum (CCS) and Hamming Distance Spectrum (HDS) for DAC. In this paper, we make use of CCS and HDS to analyze tailed DAC, a form of DAC mapping the last few symbols of each source block onto non-overlapped intervals as traditional AC. We first derive the exact HDS formula for tailless DAC, a form of DAC mapping all symbols of each source block onto overlapped intervals, and show that the HDS formula previously given is actually an approximate version. Then the HDS formula is extended to tailed DAC. We also deduce the average codebook cardinality, which is closely related to decoding complexity, and rate loss of tailed DAC with the help of CCS. The effects of tail length are extensively analyzed. It is revealed that by increasing tail length to a value not close to the bitstream length, closely-spaced codewords within the same codebook can be removed at the cost of a higher decoding complexity and a larger rate loss. Finally, theoretical analyses are verified by experiments

Hamming distance spectrum of DAC codes for equiprobable binary sources

Distributed Arithmetic Coding (DAC) is an effective technique for implementing Slepian-Wolf coding (SWC). It has been shown that a DAC code partitions source space into unequal-size codebooks, so that the overall performance of DAC codes depends on the cardinality and structure of these codebooks. The problem of DAC codebook cardinality has been solved by the so-called Codebook Cardinality Spectrum (CCS). This paper extends the previous work on CCS by studying the problem of DAC codebook structure.We define Hamming Distance Spectrum (HDS) to describe DAC codebook structure and propose a mathematical method to calculate the HDS of DAC codes. The theoretical analyses are verified by experimental results

3-D neurohistology of transparent tongue in health and injury with optical clearing

Tongue receives extensive innervation to perform taste, sensory, and motor functions. Details of the tongue neuroanatomy and its plasticity in response to injury offer insights to investigate tongue neurophysiology and pathophysiology. However, due to the dispersed nature of the neural network, standard histology cannot provide a global view of the innervation. We prepared transparent mouse tongue by optical clearing to reveal the spatial features of the tongue innervation and its remodeling in injury. Immunostaining of neuronal markers, including PGP9.5 (pan-neuronal marker), calcitonin gene-related peptide (sensory nerves), tyrosine hydroxylase (sympathetic nerves), and vesicular acetylcholine transporter (cholinergic parasympathetic nerves and neuromuscular junctions), was combined with vessel painting and nuclear staining to label the tissue network and architecture. The tongue specimens were immersed in the optical-clearing solution to facilitate photon penetration for 3-dimensiontal (3-D) confocal microscopy. Taking advantage of the transparent tissue, we simultaneously revealed the tongue microstructure and innervation with subcellular-level resolution. 3-D projection of the papillary neurovascular complex and taste bud innervation was used to demonstrate the spatial features of tongue mucosa and the panoramic imaging approach. In the tongue injury induced by 4-nitroquinoline 1-oxide administration in the drinking water, we observed neural tissue remodeling in response to the changes of mucosal and muscular structures. Neural networks and the neuromuscular junctions were both found rearranged at the peri-lesional region, suggesting the nerve-lesion interactions in response to injury. Overall, this new tongue histological approach provides a useful tool for 3-D imaging of neural tissues to better characterize their roles with the mucosal and muscular components in health and disease

Diversity of the Photoreceptors and Spectral Opponency in the Compound Eye of the Golden Birdwing, Troides aeacus formosanus

The compound eye of the Golden Birdwing, Troides aeacus formosanus (Papilionidae, Lepidoptera), is furnished with three types of ommatidia, which are clearly different in pigmentation around the rhabdom. Each ommatidium contains nine photoreceptors, whose spectral sensitivities were analyzed electrophysiologically. We identified nine spectral types of photoreceptor with sensitivities peaking at 360 nm (UV), 390 nm (V), 440 nm (B), 510 nm (BG), 540 nm (sG), 550 nm (dG), 580 nm (O), 610 nm (R), and 630 nm (dR) respectively. The spectral sensitivities of the V, O, R and dR receptors did not match the predicted spectra of any visual pigments, but with the filtering effects of the pigments around the rhabdom, they can be reasonably explained. In some of the receptors, negative-going responses were observed when they were stimulated at certain wavelengths, indicating antagonistic interactions between photoreceptors

Experimental ten-photon entanglement

Quantum entanglement among multiple spatially separated particles is of fundamental interest, and can serve as central resources for studies in quantum nonlocality, quantum-to-classical transition, quantum error correction, and quantum simulation. The ability of generating an increasing number of entangled particles is an important benchmark for quantum information processing. The largest entangled states were previously created with fourteen trapped ions, eight photons, and five superconducting qubits. Here, based on spontaneous parametric down-converted two-photon entanglement source with simultaneously a high brightness of ~12 MHz/W, a collection efficiency of ~70% and an indistinguishability of ~91% between independent photons, we demonstrate, for the first time, genuine and distillable entanglement of ten single photons under different pump power. Our work creates a state-of-the-art platform for multi-photon experiments, and provide enabling technologies for challenging optical quantum information tasks such as high-efficiency scattershot boson sampling with many photons.Comment: 65 pages, supplementary information included, with all raw data. to appear in Physical Review Letter

Cloud-Resolving Modeling of Aerosol Indirect Effects in Idealized Radiative-Convective Equilibrium with Interactive and Fixed Sea Surface Temperature

This study aims to evaluate the impact of aerosol indirect effects (AIEs) on climate variations over tropical oceans through a three-dimensional cloud-resolving model, the System for Atmospheric Modeling, in idealized radiative-convective equilibrium (RCE). In RCE framework, the interactions among radiation, convection and surface fluxes are explicitly included while the effects of the large-scale circulation on convection are ignored. The AIEs on RCE are modeled by varying the number concentration of cloud condensation nuclei (CCN), served as a proxy for the aerosol amount in the environment, over a wide range starting from pristine maritime (50 cm-3) to polluted (1000 cm-3) conditions. Two sets of experiments are performed: (1) with an interactive sea surface temperature (SST) predicted by the simple slab ocean model and (2) with a prescribed SST fixed at 300 K. For simplicity, both experimental sets were run with constant insolation and removed diurnal cycle. In interactive SST runs, it took several hundred days until they reach a quasi-equilibrium state. Simulation results show that the presence of CCN causes reduced longwave cloud radiative forcing (0.6-2.5 W m-2) but enhanced shortwave cloud radiative forcing (0.3-1.5 W m-2) in both the interactive SST (ISST) and fixed SST (FSST) experiments. In the ISST runs with the highest CCN count, AIEs mitigate most, 1.5 K, of the greenhouse warming, 2 K, as simulated by the doubling-CO2 experiment. It is found in both ISST and FSST runs that the increase of CCN count tends to decrease the low-cloud and high-cloud covers, but increase the middle cloud cover, enhance cloud liquid water path, snow, and graupel water paths, but reduce cloud ice and rainwater paths. The qualitative differences in hydrological cycle between the ISST and FSST are also found. In ISST runs, cooler SSTs resulted from enhanced CCN counts tend to reduce precipitable water, latent heat flux and, consequently, decrease surface precipitation rate. In the FSST runs, on the other hand, the effects are opposite, that is slightly increased latent heat flux, constant PW and increased surface precipitation rate. These differences suggest that the estimates of AIEs over tropical oceans can be quite sensitive to the choice of the fixed or interactive SST framework. | 65 page