Optical and mechanical properties in photorefractive crystal based ultrasound-modulated optical tomography

Ultrasound-modulated optical tomography (UOT) is a new technique that combines laser light and ultrasound to provide images with good optical contrast and good ultrasound resolution in soft biological tissue. We improve the method proposed by Murray et al to obtain UOT images in thick biological tissues with the use of photorefractive crystal based interferometers. It is found that a long ultrasound burst (on the order of a millisecond) can improve the signal-to-noise ratio dramatically. Also with a long ultrasound burst, the response of the acoustic radiation force impulses can be clearly observed in the UOT signal, which will help to acquire images that record both the optical and mechanical properties of biological soft tissues

Photorefractive detection of tissue optical and mechanical properties by ultrasound modulated optical tomography

Ultrasound-modulated optical tomography is a developing hybrid imaging modality that combines high optical contrast and good ultrasonic resolution for imaging soft biological tissue. We developed a photorefractive-crystal-based, time-resolved detection scheme with the use of a millisecond long ultrasound burst to image both the optical and the mechanical properties of biological tissues, with improved detection efficiency of ultrasound-tagged photons

Screening and analysis of soda saline-alkali stress induced up- regulated genes in sugar sorghum

Soil salinization severely constrains the growth of crops, which ultimately leads to reduced yields. Because Sorghum dochna (common name sugar sorghum) has the advantageous properties of excellent salt stress resis- tance, high biomass, and tremendous flexibility for utilization as food, livestock feed, and industrial products, this species holds great potential to be further developed as a primary alternative crop. To elucidate the molecular mechanism that governs sugar sorghum’s adaptation to high salinity environments, we constructed a suppression subtractive hybridization (SSH) cDNA library from sugar sorghum transcripts that contains the soda saline-alkali induced up-regulated genes from the resistant variety M-81E. The SSH cDNA library was screened by using the colony hybridization method, and the ESTs obtained were sequenced and analyzed. A total of 200 EST clones were identified, representing 127 unigenes (6 contigs and 121 singlets). A Blast analysis showed that 48 ESTs (46.6%) have annotated functions in GenBank, 55 ESTs (53.4%) have unknown functions (or encode hypothetical proteins), and 24 ESTs (18.9%) have no blast hits. The majority of the hypothetical ESTs from the cDNA library displayed very high sequence similarity with their homologs found through GenBank. A clustering analysis of the ESTs with known functions indicated that a wide variety of genes were induced during the salt stress treatment. These genes were found to function in photosynthesis, material and energy metabolism (carbohydrates, lipids, amino acids, co-enzymes, ions, etc.), synthesis or maintenance of constituents of the cell wall and cell membrane, signal transduction, transcriptional regulation, and as water channels. This indicates that sugar sorghum tolerance to soda saline-alkali stress results from the coordinated functions of many genes

Optical and mechanical properties in photorefractive crystal based ultrasound-modulated optical tomography

Ultrasound-modulated optical tomography (UOT) is a new technique that combines laser light and ultrasound to provide images with good optical contrast and good ultrasound resolution in soft biological tissue. We improve the method proposed by Murray et al to obtain UOT images in thick biological tissues with the use of photorefractive crystal based interferometers. It is found that a long ultrasound burst (on the order of a millisecond) can improve the signal-to-noise ratio dramatically. Also with a long ultrasound burst, the response of the acoustic radiation force impulses can be clearly observed in the UOT signal, which will help to acquire images that record both the optical and mechanical properties of biological soft tissues

Photorefractive detection of tissue optical and mechanical properties by ultrasound modulated optical tomography

Ultrasound-modulated optical tomography is a developing hybrid imaging modality that combines high optical contrast and good ultrasonic resolution for imaging soft biological tissue. We developed a photorefractive-crystal-based, time-resolved detection scheme with the use of a millisecond long ultrasound burst to image both the optical and the mechanical properties of biological tissues, with improved detection efficiency of ultrasound-tagged photons

Self-adaptive seismic data reconstruction and denoising using dictionary learning based on morphological component analysis

Data reconstruction and data denoising are two critical preliminary steps in seismic data processing. Compressed Sensing states that a signal can be recovered by a series of solving algorithms if it is sparse in a transform domain, and has been well applied in the field of reconstruction, when, sparse representation of seismic data is the key point. Considering the complexity and diversity of seismic data, a single mathematical transformation will lead to incomplete sparse expression and bad restoration effects. Morphological Component Analysis (MCA) decomposes a signal into several components with outstanding morphological features to approximate the complex internal data structure. However, the representation ability of combined dictionaries is constrained by the number of dictionaries, and cannot be self-adaptively matched with the data features. Dictionary learning overcomes the limitation of fixed base function by training dictionaries that are fully suitable for processed data, but requires huge amount of time and considerable hardware cost. To solve the above problems, a new dictionary library (K-Singluar Value Decomposition learning dictionary and Discrete Cosine Transform dictionary) is hereby proposed based on the efficiency of fixed base dictionary and the high precision of learning dictionary. The self-adaptive sparse representation is achieved under the Morphological Component Analysis framework and is successfully applied to the reconstruction and denoising of seismic data. Real data tests have proved that the proposed method performs better than single mathematical transformation and other combined dictionaries

Screening and analysis of soda saline-alkali stress induced up- regulated genes in sugar sorghum

Soil salinization severely constrains the growth of crops, which ultimately leads to reduced yields. Because Sorghum dochna (common name sugar sorghum) has the advantageous properties of excellent salt stress resistance, high biomass, and tremendous flexibility for utilization as food, livestock feed, and industrial products, this species holds great potential to be further developed as a primary alternative crop. To elucidate the molecular mechanism that governs sugar sorghum’s adaptation to high salinity environments, we constructed a suppression subtractive hybridization (SSH) cDNA library from sugar sorghum transcripts that contains the soda saline-alkali induced up-regulated genes from the resistant variety M-81E. The SSH cDNA library was screened by using the colony hybridization method, and the ESTs obtained were sequenced and analyzed. A total of 200 EST clones were identified, representing 127 unigenes (6 contigs and 121 singlets). A Blast analysis showed that 48 ESTs (46.6%) have annotated functions in GenBank, 55 ESTs (53.4%) have unknown functions (or encode hypothetical proteins), and 24 ESTs (18.9%) have no blast hits. The majority of the hypothetical ESTs from the cDNA library displayed very high sequence similarity with their homologs found through GenBank. A clustering analysis of the ESTs with known functions indicated that a wide variety of genes were induced during the salt stress treatment. These genes were found to function in photosynthesis, material and energy metabolism (carbohydrates, lipids, amino acids, co-enzymes, ions, etc.), synthesis or maintenance of constituents of the cell wall and cell membrane, signal transduction, transcriptional regulation, and as water channels. This indicates that sugar sorghum tolerance to soda saline-alkali stress results from the coordinated functions of many genes

Search for Quasi-Periodical Oscillations in Precursors of Short and Long Gamma Ray Bursts

The precursors of short and long Gamma Ray Bursts (SGRBs and LGRBs) can serve as probes of their progenitors, as well as shedding light on the physical processes of mergers or core-collapse supernovae. Some models predict the possible existence of Quasi-Periodically Oscillations (QPO) in the precursors of SGRBs. Although many previous studies have performed QPO search in the main emission of SGRBs and LGRBs, so far there was no systematic QPO search in their precursors. In this work, we perform a detailed QPO search in the precursors of SGRBs and LGRBs detected by Fermi/GBM from 2008 to 2019 using the power density spectrum (PDS) in frequency domain and Gaussian processes (GP) in time domain. We do not find any convinced QPO signal with significance above 3 $\sigma$, possibly due to the low fluxes of precursors. Finally, the PDS continuum properties of both the precursors and main emissions are also studied for the first time, and no significant difference is found in the distributions of the PDS slope for precursors and main emissions in both SGRBs and LGRBs.Comment: submitte

The Minimum Variation Timescales of X-ray bursts from SGR J1935+2154

The minimum variation timescale (MVT) of soft gamma-ray repeaters can be an important probe to estimate the emission region in pulsar-like models, as well as the Lorentz factor and radius of the possible relativistic jet in gamma-ray burst (GRB)-like models, thus revealing their progenitors and physical mechanisms. In this work, we systematically study the MVTs of hundreds of X-ray bursts (XRBs) from SGR J1935+2154 observed by {\it Insight}-HXMT, GECAM and Fermi/GBM from July 2014 to Jan 2022 through the Bayesian Block algorithm. We find that the MVTs peak at $\sim$ 2 ms, corresponding to a light travel time size of about 600 km, which supports the magnetospheric origin in pulsar-like models. The shock radius and the Lorentz factor of the jet are also constrained in GRB-like models. Interestingly, the MVT of the XRB associated with FRB 200428 is $\sim$ 70 ms, which is longer than that of most bursts and implies its special radiation mechanism. Besides, the median of MVTs is 7 ms, shorter than the median MVTs of 40 ms and 480 ms for short GRBs or long GRBs, respectively. However, the MVT is independent of duration, similar to GRBs. Finally, we investigate the energy dependence of MVT and suggest that there is a marginal evidence for a power-law relationship like GRBs but the rate of variation is at least about an order of magnitude smaller. These features may provide an approach to identify bursts with a magnetar origin.Comment: accepted for publication in ApJ