Analysis of THz generation through the asymmetry of photoelectron angular distributions

Citation: Zhou, Z. Y., Wang, X., & Lin, C. D. (2017). Analysis of THz generation through the asymmetry of photoelectron angular distributions. Physical Review A, 95(3), 6. doi:10.1103/PhysRevA.95.033418We analyze the mechanism of THz generation in a gas medium with intense two-color infrared lasers pulses. The dependence of the amplitude of THz emission on the relative phase between the fundamental color (800 nm) and its second harmonic (400 nm) is shown to be identical to the residual current as well as to the asymmetry of the above-threshold-ionization (ATI) photoelectrons along the left versus the right side of the linear polarization axis of the laser, thus confirming the validity of the semiclassical photocurrent model for the THz emission. We further analyze the even vs odd angular momentum distributions of the ATI electrons. The degree of overlap between the even-parity dominant electrons and the odd-parity dominant electrons within each ATI peak determines the strength of the THz emission, thus favoring the model that THz is generated through free-free transitions in the laser field. A model is also provided to obtain the same phase dependence as the four-wave mixing model

Ticking terahertz wave generation in attoseconds

We perform a joint measurement of terahertz waves and high-order harmonics generated from noble atoms driven by a fundamental laser pulse and its second harmonic. By correlating their dependence on the phase-delay of the two pulses, we determine the generation of THz waves in tens of attoseconds precision. Compared with simulations and models, we find that the laser-assisted soft-collision of the electron wave packet with the atomic core plays a key role. It is demonstrated that the rescattering process, being indispensable in HHG processes, dominant THz wave generation as well but in a more elaborate way. The new finding might be helpful for the full characterization of the rescattering dynamics.Comment: 4 figure

Theory of Retrieving Orientation-Resolved Molecular Information using Time-Domain Rotational Coherence Spectroscopy

We provide a unified theoretical framework for recently emerging experiments that retrieve fixed-in-space molecular information through time-domain rotational coherence spectroscopy. Unlike a previous approach by Makhija et al. (V. Makhija, arXiv:1611.06476), our method can be applied to the retrieval of both real-valued (e.g., ionization yield) and complex-valued (e.g., induced dipole moment) molecular response information. It is also a direct retrieval method without using iterations. We also demonstrate that experimental parameters, such as the fluence of the aligning laser pulse and the rotational temperature of the molecular ensemble, can be quite accurately determined using a statistical method

Skeleton-Guided Instance Separation for Fine-Grained Segmentation in Microscopy

One of the fundamental challenges in microscopy (MS) image analysis is instance segmentation (IS), particularly when segmenting cluster regions where multiple objects of varying sizes and shapes may be connected or even overlapped in arbitrary orientations. Existing IS methods usually fail in handling such scenarios, as they rely on coarse instance representations such as keypoints and horizontal bounding boxes (h-bboxes). In this paper, we propose a novel one-stage framework named A2B-IS to address this challenge and enhance the accuracy of IS in MS images. Our approach represents each instance with a pixel-level mask map and a rotated bounding box (r-bbox). Unlike two-stage methods that use box proposals for segmentations, our method decouples mask and box predictions, enabling simultaneous processing to streamline the model pipeline. Additionally, we introduce a Gaussian skeleton map to aid the IS task in two key ways: (1) It guides anchor placement, reducing computational costs while improving the model's capacity to learn RoI-aware features by filtering out noise from background regions. (2) It ensures accurate isolation of densely packed instances by rectifying erroneous box predictions near instance boundaries. To further enhance the performance, we integrate two modules into the framework: (1) An Atrous Attention Block (A2B) designed to extract high-resolution feature maps with fine-grained multiscale information, and (2) A Semi-Supervised Learning (SSL) strategy that leverages both labeled and unlabeled images for model training. Our method has been thoroughly validated on two large-scale MS datasets, demonstrating its superiority over most state-of-the-art approaches

Prevalence of polypharmacy and potentially inappropriate medication use in older lung cancer patients: A systematic review and meta-analysis

Objectives: In older lung cancer patients, polypharmacy and the use of potentially inappropriate medications (PIMs) are commonly reported, but no systematic review or meta-analysis has been carried out to ascertain the prevalence and risk variables in this group. This study aimed to identify the prevalence of polypharmacy, PIMs and associated risk variables in older lung cancer patients.Methods: We searched for articles from the beginning to February 2022 in PubMed, Embase, and Web of Science that related the use of PIMs and polypharmacy by older lung cancer patients (PROSPERO Code No: CRD42022311603). Meta-analysis was performed on observational studies describing the prevalence and correlation of polypharmacy or PIMs in older patients with lung cancer.Results: Of the 387 citations, 6 articles involving 16,890 patients were included in the final sample. In older lung cancer patients pooled by meta-analysis, 38% and 35% of PIMs and polypharmacy, respectively. The prevalence of PIMs was 43%, 49%, and 28%, respectively, according to the 2019 AGS Beers criteria, 2014 screening tool for older people’s prescriptions/screening tool for alerting to the proper therapy (STOPP/START criteria) criteria, and other criteria.Conclusion: This systematic review and meta-analysis demonstrated a high prevalence of polypharmacy and PIMs among older lung cancer patients. Therefore, it is essential to take rational interventions for older lung cancer patients to receive reasonable pharmacotherapy.Systematic Review Registration: [https://www.crd.york.ac.uk/PROSPERO/], identifier [CRD42022311603]

Theory of retrieving orientation-resolved molecular information using time-domain rotational coherence spectroscopy

Citation: Wang, X., Le, A.-T., Zhou, Z., Wei, H., & Lin, C. D. (2017). Theory of retrieving orientation-resolved molecular information using time-domain rotational coherence spectroscopy. Physical Review A, 96(2), 023424. https://doi.org/10.1103/PhysRevA.96.023424We provide a unified theoretical framework for recently emerging experiments that retrieve fixed-in-space molecular information through time-domain rotational coherence spectroscopy. Unlike a previous approach by Makhija et al. (V. Makhija et al., arXiv:1611.06476), our method can be applied to the retrieval of both real-valued (e.g., ionization yield) and complex-valued (e.g., induced dipole moment) molecular response information. It is also a direct retrieval method without using iterations. We also demonstrate that experimental parameters, such as the fluence of the aligning laser pulse and the rotational temperature of the molecular ensemble, can be quite accurately determined using a statistical method

New mitogenomes in deep-water endemic Cocculinida and Neomphalida shed light on lineage-specific gene orders in major gastropod clades

Gastropoda is the most speciose class in Mollusca, the second largest animal phylum, whose internal relationships remain largely unsettled, partly due to the insufficient data from key deep-water endemic lineages, such as the subclass Neomphaliones. Neomphaliones currently includes two orders: Cocculinida, best known from sunken wood habitats, and Neomphalida, best known from hydrothermal vents and often referred to as the ‘hot vent clade’. Phylogenetic controversy has also been observed in this subclass across different studies, requesting additional investigations. Here, we assembled nine new mitogenomes from two cocculinids and seven neomphalines and analyzed them with published gastropod mitogenomes, with a particular focus on Neomphaliones. The phylogenetic reconstruction of Gastropoda based on 13 mitochondrial protein-coding genes resulted in a topology largely congruent with previous reconstructions based on morphological characters. Furthermore, we recovered characteristic mitochondrial gene order arrangements of Cocculinida and Neomphalida compared to the hypothetical ancestral gastropod gene order, at a level similar to other subclass-level clades. Divergence time estimation showed that Cocculinida and Neomphalida diverged approximately 322.68 million years ago. In addition to characteristic gene order arrangements for the clade, cocculinid mitogenomes also exhibit some minor rearrangements even among congeners. Within Neomphalida, our tree adds support to monophyletic Peltospiridae and Neomphalidae, with unique gene arrangement recovered for each family. Our results offer new insights into the rearrangement of mitogenomes in Gastropoda, providing another clue to the evolutionary history of gastropods

All-small-molecule organic solar cells with over 14% efficiency by optimizing hierarchical morphologies

The high efficiency all-small-molecule organic solar cells (OSCs) normally require optimized morphology in their bulk heterojunction active layers. Herein, a small-molecule donor is designed and synthesized, and single-crystal structural analyses reveal its explicit molecular planarity and compact intermolecular packing. A promising narrow bandgap small-molecule with absorption edge of more than 930 nm along with our home-designed small molecule is selected as electron acceptors. To the best of our knowledge, the binary all-small-molecule OSCs achieve the highest efficiency of 14.34% by optimizing their hierarchical morphologies, in which the donor or acceptor rich domains with size up to ca. 70 nm, and the donor crystals of tens of nanometers, together with the donor-acceptor blending, are proved coexisting in the hierarchical large domain. All-small-molecule photovoltaic system shows its promising for high performance OSCs, and our study is likely to lead to insights in relations between bulk heterojunction structure and photovoltaic performance.Funding Agencies|Ministry of Science and Technology of ChinaMinistry of Science and Technology, China [2016YFA0200700, 2016YFF0203803]; National Natural Science Foundation of ChinaNational Natural Science Foundation of China [51961135103, 51973043, 21822503, 21534003, 21721002]; Beijing Nova ProgramBeijing Municipal Science &amp; Technology Commission [Z17110001117062]; Youth Innovation Promotion Association; K.C.Wong Education Foundation; Chinese Academy of SciencesChinese Academy of Sciences; Swedish Research Council VRSwedish Research Council [2018-06048, 2018-05484]</p

Role of astrocytes in the repair of auditory synapses in the cochlear nucleus after noise damage

Objective·To investigate the pathological and physiological changes underlying noise-induced cochlear nucleus damage and the regulating function of astrocytes on the damage, using a combination of morphological analysis, and molecular biology techniques.Methods·Forty-eight male C57BL/6J mice were randomly divided into two groups and exposed to 110 dB SPL (sound pressure level) broadband noise for 2 hours. Auditory brainstem response (ABR) tests were performed on the mice on days 1, 7, 14, 30, and 90 after the noise exposure. Immunofluorescence staining of cochlear nuclear tissue was conducted to observe cochlear nuclear neurons and auditory synapses, as well as astrocyte activation levels. In addition, the damage to the cochlear nuclear neurons and synapses caused by noise was verified through Western blotting.Results·A significant decrease in cochlear nuclear Bushy cells after noise exposure was observed. The Western blotting results showed that there was severe loss of nerve fibers in cochlear nuclear neurons, indicating that noise caused significant damage to cochlear nucleus neurons. Moreover, a significant loss of auditory synapses labeled with vesicular glutamate transporter 1 (Vglut1) was observed, which was the severest on day 14 after noise exposure and slowly recovered on day 90. Interestingly, astrocytes in the cochlear nucleus displayed obvious clustering and activation after noise exposure. By staining with glial fibrillary acidic protein (GFAP), most astrocytes were distributed around the cochlear nucleus, granule cell area, and auditory nerve root before noise exposure, and they had a small size. However, on day 14 after noise exposure, a large number of activated astrocytes aggregated in the ventral cochlear nucleus, and they all showed a pattern of growth around the synapses.Conclusion·Noise exposure leads to significant damage in the cochlear nucleus, and it is possible that astrocytes are involved in its damage and repair processes. These findings will provide a crucial foundation for further understanding the mechanisms of sound signal analysis, integration, and neural plasticity in the cochlear nucleus

Multi-Step Ahead Short-Term Electricity Load Forecasting Using VMD-TCN and Error Correction Strategy

The electricity load forecasting plays a pivotal role in the operation of power utility companies precise forecasting and is crucial to mitigate the challenges of supply and demand in the smart grid. More recently, the hybrid models combining signal decomposition and artificial neural networks have received popularity due to their applicability to reduce the difficulty of prediction. However, the commonly used decomposition algorithms and recurrent neural network-based models still confront some dilemmas such as boundary effects, time consumption, etc. Therefore, a hybrid prediction model combining variational mode decomposition (VMD), a temporal convolutional network (TCN), and an error correction strategy is proposed. To address the difficulty in determining the decomposition number and penalty factor for VMD decomposition, the idea of weighted permutation entropy is introduced. The decomposition hyperparameters are optimized by using a comprehensive indicator that takes account of the complexity and amplitude of the subsequences. Besides, a temporal convolutional network is adopted to carry out feature extraction and load prediction for each subsequence, with the primary forecasting results obtained by combining the prediction of each TCN model. In order to further improve the accuracy of prediction for the model, an error correction strategy is applied according to the prediction error of the train set. The Global Energy Competition 2014 dataset is employed to demonstrate the effectiveness and practicality of the proposed hybrid model. The experimental results show that the prediction performance of the proposed hybrid model outperforms the contrast models. The accuracy achieves 0.274%, 0.326%, and 0.405 for 6-steps, 12-steps, and 24 steps ahead forecasting, respectively, in terms of the mean absolute percentage error