X-ray free-electron lasers can generate intense and coherent radiation at wavelengths down to the sub-ångström region
, and have become indispensable tools for applications in structural biology and ...chemistry, among other disciplines
. Several X-ray free-electron laser facilities are in operation
; however, their requirement for large, high-cost, state-of-the-art radio-frequency accelerators has led to great interest in the development of compact and economical accelerators. Laser wakefield accelerators can sustain accelerating gradients more than three orders of magnitude higher than those of radio-frequency accelerators
, and are regarded as an attractive option for driving compact X-ray free-electron lasers
. However, the realization of such devices remains a challenge owing to the relatively poor quality of electron beams that are based on a laser wakefield accelerator. Here we present an experimental demonstration of undulator radiation amplification in the exponential-gain regime by using electron beams based on a laser wakefield accelerator. The amplified undulator radiation, which is typically centred at 27 nanometres and has a maximum photon number of around 10
per shot, yields a maximum radiation energy of about 150 nanojoules. In the third of three undulators in the device, the maximum gain of the radiation power is approximately 100-fold, confirming a successful operation in the exponential-gain regime. Our results constitute a proof-of-principle demonstration of free-electron lasing using a laser wakefield accelerator, and pave the way towards the development of compact X-ray free-electron lasers based on this technology with broad applications.
Abstract
Existing problems for 3D extended target tracking and contour reconstruction under clutter environment are thoroughly investigated in this article. Due to the sparsity of available point ...cloud data and interference from clutter, the shape completion method, such as Point Completion Network (PCN), cannot reconstruct 3D contour directly. Moreover, the traditional Gaussian process (GP) model suffered from computing overhead and cannot handle irregular non‐convex shapes. Here, a two‐stage tracking algorithm is proposed, which firstly combines the 3D GP measurement model with a probability data association filter to jointly estimate the kinematics and 3D Gaussian basis points, which contain partial shape information. Afterwards, this method input produced Gaussian basis points to a deep learning‐based PCN to reconstruct complete geometry of the contour. The effectiveness of the proposed algorithm is verified by extended target tracking with both simple and complex geometric shapes. The simulation results show that the proposed algorithm obtains accurate kinematic state estimation and produces complete point cloud estimation for 3D contour.
Abstract Understanding the intricate interactions governing protein and peptide behavior in liquid–liquid phase separation (LLPS) is crucial for unraveling biological functions and dysfunctions. This ...study employs a residue-leveled coarse-grained molecular dynamics approach to simulate the phase separation of repetitive polyproline and polyarginine peptides (poly PR) with varying lengths and sequences in solution, considering different concentrations and temperatures. Our findings highlight the crucial role of sequence order in promoting LLPS in peptides with identical lengths of repetitive sequences. Interestingly, repetitive peptides containing fewer than 10 polyarginine repeats exhibit no LLPS, even at salt concentrations up to 3 M. Notably, our simulations align with experimental observations, pinpointing a salt concentration of 2.7 M for PR25-induced LLPS. Utilizing the same methodology, we predict the required salt concentrations for LLPS induction as 1.2 M, 1.5 M, and 2.7 M for PR12, PR15, and PR35, respectively. These predictions demonstrate good agreement with experimental results. Extending our investigation to include the peptide glutamine and arginine (GR15) in DNA solution, our simulations mirror experimental observations of phase separation. To unveil the molecular forces steering peptide phase separation, we introduce a dielectric constant modifier and hydrophobicity disruptor into poly PR systems. Our coarse-grained analysis includes an examination of temperature effects, leading to the inference that both hydrophobic and electrostatic interactions drive phase separation in peptide systems.
The base excision repair (BER) pathway is an important defense response to oxidative DNA damage. It is known that exposures to phthalate esters (PAEs), including Dibutyl phthalate (DBP), ...Mono-(2-ethylhexyl) phthalate (MEHP), and Di-(2-ethylhexyl) phthalate (DEHP), cause reactive oxygen species-induced DNA damage and oxidative stress. Here, we determined the mRNA levels of BER pathway-related genes (ogg1, nthl1, apex1, parp1, xrcc1, lig3, ung, pcna, polb, pold, fen1, and lig1), pro-apoptotic gene (bax), and apoptotic suppressor gene (bcl2) in different PAEs-exposed zebrafish larvae and HEK293T cells. Further investigations were performed to examine reactive oxygen species (ROS) accumulation, superoxide dismutase (SOD) activity, developmental toxicity, and cell viability after PAEs exposure in vivo and in vitro. The results showed that PAEs exposure can induce developmental abnormalities in zebrafish larvae, and inhibit cell viability in HEK293T cells. Additionally, we found that PAEs exposure results in the accumulation of ROS and the inhibition of SOD activation in vivo and in vitro. Notably, the mRNA levels of BER pathway-related genes (OGG1, NTHL1, APEX1, XRCC1, UNG, POLB, POLD, FEN1) were significantly upregulated after DBP or MEHP exposure, whereas the mRNA levels of NTHL1, UNG, POLB, POLD, and FEN1 were significantly altered in DEHP-treated HEK293T cells. In zebrafish, the mRNA levels of ogg1, pcna, fen1 and lig1 genes were increased after DBP or DEHP exposure, whereas the mRNA levels of nthl1, apex1, parp1, lig3, pcna and polb were decreased after MEHP exposure, respectively. Thus, our findings indicated that PAEs exposure can induce developmental toxicity, cytotoxicity, and oxidative stress, as well as activate BER pathway in vivo and in vitro, suggesting that BER pathway might play critical roles in PAEs-induced oxidative stress through repairing oxidative DNA damage.
•PAEs effects the development of zebrafish embryos.•PAEs decreases cell viability in HEK293T cells.•PAEs increases the production of ROS and decreases SOD activity in vivo and in vitro.•PAEs increases pro-apoptotic gene expression and decreases anti-apoptotic gene expression.•BER pathway were activated in response to PAEs exposure (with the exceptions of larvae at 50 μM MEHP) in vivo and vitro.
The aim of the experiment was to study the effects of feeding blends of sorbic acid, fumaric acid, and thymol (EOA) on growth performance, digestive functions, and immunity of broiler chickens. A ...total of 640 one-day-old male Cobb 500 chicks with similar BW (41.8 ± 0.6 g) were randomly divided into 4 dietary treatment groups consisting of 10 replicates with 16 birds per replicate and fed a basal diet until d 42 (CON) or diets with 0.15 g/kg enramycin during the grower period (AG), 0.30 g/kg EOA during the grower period (EG), or 0.30 g/kg EOA during the finisher period (EF). At d 42, the feed conversion ratio was reduced (P < 0.05) for birds in EG group compared with other groups. Birds in EG group showed a higher villus height of the duodenum and jejunum and muscular layers of the duodenum and ileum than birds in CON group (P < 0.05). Compared with other groups, crypt depth of the jejunum and ileum was markedly increased (P < 0.05) by EOA supplementation during the finisher period at d 42. The EOA supplementation during grower period increased significantly lipase, trypsin and chymotrypsin activities of the duodenum at d 21 and 42, as well as lipase and trypsin at d 21, and trypsin and chymotrypsin at d 42 in the jejunum, and trypsin and chymotrypsin activities of the ileum at d 21 compared to the control diet (P < 0.05). Birds of EG and EF groups showed a higher (P < 0.05) spleen index than birds of CON group. The level of secretory immunoglobulin A in duodenal and ileal mucosa was increased (P < 0.05) in EF group at d 42 compared with other groups. In conclusion, the results indicate that EOA can be effectively applied in broiler diets, especially during the grower phase by improving intestinal morphology and increasing digestive enzyme activity.
A recent paper E. Masazade, R. Niu, P. K. Varshney, and M. Keskinoz, "Energy Aware Iterative Source Localization for Wireless Sensor Networks", IEEE Transactions on Signal Processing, vol. 58, no. 9, ...pp. 4824-4835, 2010 presents an iterative source localization scheme based on the selection of sensors. An importance sampling based Monte Carlo method was employed at each iteration using the entire received data to approximate the posterior distribution of the source location in the paper. In this note, we propose an alternative sequential importance sampling and resampling algorithm to implement the iterative source localization. The proposed method provides significant performance improvement over the current method via combination of auxiliary particle filtering with kernel smoothing approximation. The superiority of the alternative algorithm is verified by Monte Carlo simulation results.
In practice, many practical problems occur in uncertain environments, especially in situations that involve human subjective evaluation such as that in the analytic hierarchy process (AHP). This ...paper presents a practical multi-criteria group decision-making method for decision making under uncertainty. To handle the randomness and fuzziness of individual judgments, the normal Cloud model, group decision-making technique, and the Delphi feedback method are adopted. In the proposed Cloud Delphi hierarchical analysis (CDHA), experts are asked to express their judgments using interval numbers. Individual fuzziness and randomness are then mined from the interval-value comparison matrices. Subsequently, the interval-value pairwise comparison matrices are converted into the corresponding Cloud matrices, and the one-iteration Delphi process is executed to diminish individual judgment mistakes. The individual Cloud weight vectors are calculated using the geometric mean technique and are finally weighted to form the group Cloud weight vector. A simple case study that involved reproducing the relative area sizes of six provinces in China shows that the CDHA method can effectively reduce mistakes and improve decision makers’ judgments in situations that require subjective expertise and judgmental inputs. In addition, a practical decision-making problem in which houses are ranked by home buyers shows that the proposed method is effective when applied to complex, large, multidisciplinary problems with considerable uncertainties.
The protection of Lactobacillus plantarum JM113 against deoxynivalenol (DON)-induced apoptosis and intestinal inflammation on the jejunum of broiler chickens and the potential roles of gut microbiota ...were determined. A total of 144 one-day-old male broilers (Arbor Acres) were randomly divided into 3 treatment groups consisting of 6 replicates with 8 birds per replicate, including the CON (basal diet), the DON (basal diet + 10 mg/kg DON), and the DL (basal diet + 10 mg/kg DON + 1 × 109 CFU/kg L. plantarum JM113). The DON-diet decreased (P < 0.05) the mRNA expression of mucosal defense proteins and mechanistic target of rapamycin pathway genes. Meanwhile, DON challenge significantly increased Bcl-2-associated X gene/B-cell lymphoma 2 gene (Bcl-2) in the jejunum (P < 0.05) and demonstrated proapoptosis status. In contrast, the DL group showed normal immunity-related gene expression of jejunal mucosa and manifested a superior antiapoptosis status. Adding L. plantarum JM113 significantly raised (P < 0.05) propionic acid, n-butyric acid, and total short-chain fatty acids concentrations in cecal contents of birds fed with DON diet. In addition, DON exposure altered bacterial community structure and disturbed the abundance of several bacterial phyla, families, and genera, leading to dysbiosis. Supplementation with JM113 shifted the gut microbiota composition to that of the CON group. Finally, Spearman correlation analysis suggested that most positive correlations with the mRNA expression of immunity-related and apoptosis-regulatory gene were observed within the phylum Bacteroidetes, and most negative correlations with the indicators were observed within the phylum Firmicutes. The mRNA expression of Bcl-2, TLR2, mTOR, Raptor, and RPS6KB1 (P < 0.05), which are regarded as important cell proliferation and antiapoptosis parameters, were significantly negatively associated with the relative abundances of norank_f__Erysipelotrichaceae, Subdoligranulum, and Anaeroplasma, whereas they had a strong positive correlation with Ruminococcaceae_UCG-004, Alistipes, and Ruminococcaceae_NK4A214_group. These results implied that L. plantarum JM113 supplementation could ameliorate DON-induced apoptosis and intestinal inflammation via manipulating the bacterial community composition and could be used as a potential candidate to attenuate intestinal impairments.
The unbalanced magnetic thrust caused by the mover eccentricity for the linear motor drive motion system is analytically represented. Firstly, the relative complex magnetic permeability function is ...introduced to represent the effects of the mechanical installation errors and vibrations on the mover eccentricity. Then, the distortion of the magnetic field caused by the mover eccentricity is represented based on the Maxwell equation. The spectrum characteristics of the unbalanced magnetic thrust force is analytically calculated taking into account the harmonics in the drive circuit. Finally, the validity of the theoretically analysis is verified by the experiments. The results show that the static eccentricity caused by the mechanical installation error will produce the unbalanced magnetic thrust, affecting the thrust characteristics of the linear motor. In particular, the dynamic mover eccentricity caused by the mechanical vibration will produce paired unbalanced magnetic thrust harmonics on both sides of the original thrust harmonics, deteriorating the dynamic precision and efficiency of the direct drive motion system.
The unbalanced magnetic thrust caused by the mover eccentricity for the linear motor drive motion system considering the mechanical installation errors and vibrations is analytically represented. The effects on the thrust force characteristics of the unbalanced magnetic thrust are investigated.
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