HYPRO: A Hybridly Normalized Probabilistic Model for Long-Horizon Prediction of Event Sequences

In this paper, we tackle the important yet under-investigated problem of making long-horizon prediction of event sequences. Existing state-of-the-art models do not perform well at this task due to their autoregressive structure. We propose HYPRO, a hybridly normalized probabilistic model that naturally fits this task: its first part is an autoregressive base model that learns to propose predictions; its second part is an energy function that learns to reweight the proposals such that more realistic predictions end up with higher probabilities. We also propose efficient training and inference algorithms for this model. Experiments on multiple real-world datasets demonstrate that our proposed HYPRO model can significantly outperform previous models at making long-horizon predictions of future events. We also conduct a range of ablation studies to investigate the effectiveness of each component of our proposed methods.Comment: NeurIPS 2022 camera-read

Surgical Treatment of Benign Spinal Cord Tumors

Benign spinal cord tumors (SCTs) are uncommon neoplasms that can arise within or adjacent to the spinal cord. Depending on their anatomical location, benign SCTs can be categorized as intramedullary, intradural-extramedullary, and extradural. The three most common benign SCTs are meningioma, nerve sheath tumors, and ependymoma. Both meningioma and nerve sheath tumors develop in the intradural-extramedullary compartment, while ependymoma occurs in the intramedullary space. Spinal meningiomas derive from arachnoidal cells and most commonly occur within the thoracic segment of the spine. Nerve sheath tumors, including schwannomas and neurofibromas, are closely associated with spinal nerves. Half of the spinal cord ependymomas arise in the lumbosacral segment or the filum terminale. Surgical treatment of large or symptomatic benign SCTs concentrates on total or subtotal resection of the tumors, which should be cautiously individualized based on the tumor location and histopathology. A curable complete resection should be achieved if possible while preserving the nervous function of the spinal cord and minimizing potential complications. Thoracic spinal roots may be sacrificed to acquire a total resection, yet cervical and lumbar nerve roots should be preserved prudently. Due to the vulnerable and complex anatomic nature of the spinal cord, maximal resection of the tumors can be achieved with the aid of appropriate intraoperative neural monitoring and meanwhile preserve nervous function

Pulse-spacing manipulation in a passively mode-locked multipulse fiber laser

Passively mode-locked fiber lasers have been intensively applied in various research fields. However, the passive mode-locking typically operates in free-running regime, which easily produces messy multiple pulses due to the fruitful nonlinear effects involved in optical fibers. Actively controlling those disordered pulses in a passively mode-locked laser is of great interest but rarely studied. In this work, we experimentally investigate a flexible pulse-spacing manipulation in the passively mode-locked multipulse fiber laser by both intracavity and extracavity methods. A tuning range of pulse spacing up to 1.5 ns is achieved. More importantly, continuous pulse-spacing modulation is successfully demonstrated through external optical injection. It is anticipated that the results can contribute to the understanding of laser nonlinear dynamics and pursuing the optimal performance of passively mode-locked fiber lasers for practical applications

Ultrafast spectral dynamics of dual-color-soliton intracavity collision in a mode-locked fiber laser

The single-shot spectral dynamics of dual-color-soliton collisions inside a mode-locked laser is experimentally and numerically investigated. By using the all-optically dispersive Fourier transform, we spectrally unveil the collision-induced soliton self-reshaping process, which features dynamic spectral fringes over the soliton main lobe, and the rebuilding of Kelly sidebands with wavelength drifting. Meanwhile, the numerical simulations validate the experimental observation and provide additional insights into the physical mechanism of the collision-induced spectral dynamics from the temporal domain perspective. It is verified that the dynamic interference between the soliton and the dispersive waves is responsible for the observed collision-induced spectral evolution. These dynamic phenomena not only demonstrate the role of dispersive waves in the sophisticated soliton interaction inside the laser cavity, but also facilitate a deeper understanding of the soliton's inherent stability

Novel Non-Toxic Xylene Substitute (SBO) for Histology

Xylene has been generally used as a clearing and deparaffinizing agent in histology. Because of the potential toxic and flammable nature of xylene, its substitutes have been introduced into some laboratories. In this study, we introduced a novel, non-toxic xylene substitute (SBO), which was  generated through a mixture of 86% of white oil No.2 and 14% of N-heptane. SBO had a high boiling point (188°C) and flash point (144°C) coupled with a scentless and decreased volatility. To compare the effectiveness of SBO and xylene in histology, a wide range of tissue samples from rats and human beings were processed in parallel in SBO and xylene, subjected to various staining procedures. Similar to the xylene-processed paraffin blocks, the SBO-processed counterparts were easy to section without any evidence of cell shrinkage. Assessment of the SBO-treated sections stained with hematoxylin-eosin revealed a good maintenance of cell morphology and structure, and a clear definition of the cytoplasm and the nucleus. Moreover, comparable good results were achieved between the SBO- and xylene-processed tissues in other histochemical and immunohistochemical stainings. Six-month clinical applications at one department of pathology supported the potentials of SBO as a xylene substitute. In conclusion, we suggest that SBO is a safe and efficient substitute of xylene and may probably replace xylene without losing valuable diagnostic information.Key words: SBO, clearing agent, xylene, histology, toxicit

Unveiling multi-scale laser dynamics through time-stretch and time-lens spectroscopies

Spectro-temporal studies on the nonlinear physics of complex laser dynamics are essential in approaching its ultimate performance as well as understanding interdisciplinary problems. Unfortunately, it has long been limited by the insufficient spectro-temporal resolving power of conventional temporal and spectral analyzers, particularly when an indefinite optical signal ensemble contains polychromatic mixtures of continuous-wave (CW) and short pulse. In this work, we propose a real-time optical spectro-temporal analyzer (ROSTA) with three synchronized processing channels (i.e., multi-core) for single-shot studies on laser dynamics. It simultaneously provides temporal resolutions of ~70 ps in the time domain and 10’s ns (or 10’s MHz frame rate) in the spectral domain, as well as a high spectral resolution for multiscale optical inputs, i.e., ranging from CW to fs pulses. Its non-trivial record length of up to 6.4 ms enables continuous observations of non-repetitive optical events over an extensive time period ― equivalent to a propagation distance of ~1900 km. To showcase its practical applications, ROSTA is applied to visualize the onset of passive mode-locking of a fiber laser, and interesting phenomena, i.e., evolution from quasi-CW noise burst to strong shock, transition from fluctuation to mode-locking, and coexistence of CW and mode-locked pulses, have been spectro-temporally observed in a single-shot manner for the first time. It is anticipated that ROSTA will be a powerful technology for spectro-temporal optical diagnosis in different areas involving polychromatic transients

Video-rate centimeter-range optical coherence tomography based on dual optical frequency combs by electro-optic modulators

Imaging speed and range are two important parameters for optical coherence tomography (OCT). A conventional video-rate centimeter-range OCT requires an optical source with hundreds of kHz repetition rate and needs the support of broadband detectors and electronics (>1 GHz). In this paper, a type of video-rate centimeter-range OCT system is proposed and demonstrated based on dual optical frequency combs by leveraging electro-optic modulators. The repetition rate difference between dual combs, i.e. the A-scan rate of dual-comb OCT, can be adjusted within 0~6 MHz. By down-converting the interference signal from optical domain to radio-frequency domain through dual comb beating, the down-converted bandwidth of the interference signal is less than 22.5 MHz which is at least two orders of magnitude lower than that in conventional OCT systems. A LabVIEW program is developed for video-rate operation, and the centimeter imaging depth is proved by using 10 pieces of 1-mm thick glass stacked as the sample. The effective beating bandwidth between two optical comb sources is 7 nm corresponding to ~108 comb lines, and the axial resolution of the dual-comb OCT is 158 µm. Dual optical frequency combs provide a promising solution to relax the detection bandwidth requirement in fast long-range OCT systems

Mining product adopter information from online reviews for improving product recommendation

We present in this article an automated framework that extracts product adopter information from online reviews and incorporates the extracted information into feature-based matrix factorization formore effective product recommendation. In specific, we propose a bootstrapping approach for the extraction of product adopters from review text and categorize them into a number of different demographic categories. The aggregated demographic information of many product adopters can be used to characterize both products and users in the form of distributions over different demographic categories. We further propose a graphbased method to iteratively update user- and product-related distributions more reliably in a heterogeneous user-product graph and incorporate them as features into the matrix factorization approach for product recommendation. Our experimental results on a large dataset crawled from JINGDONG, the largest B2C e-commerce website in China, show that our proposed framework outperforms a number of competitive baselines for product recommendation

A quantum-inspired classical algorithm for separable Non-negative Matrix Factorization

Non-negative Matrix Factorization (NMF) asks to decompose a (entry-wise) non-negative matrix into the product of two smaller-sized nonnegative matrices, which has been shown intractable in general. In order to overcome this issue, separability assumption is introduced which assumes all data points are in a conical hull. This assumption makes NMF tractable and is widely used in text analysis and image processing, but still impractical for huge-scale datasets. In this paper, inspired by recent development on dequantizing techniques, we propose a new classical algorithm for separable NMF problem. Our new algorithm runs in polynomial time in the rank and logarithmic in the size of input matrices, which achieves an exponential speedup in the low-rank setting