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Temperature or pressure anisotropies are characteristic of space plasmas, standard magnetohydrodynamic (MHD) model for describing large-scale plasma phenomena however usually assumes isotropic pressure. In this paper we examine the characteristics of MHD waves, fire-hose and mirror instabilities in anisotropic homogeneous magnetized plasmas. The model equations are a set of gyrotropic MHD equations closed by the generalized Chew-Goldberger-Low (CGL) laws with two polytropic exponents representing various thermodynamic conditions. Both ions and electrons are allowed to have separate plasma beta, pressure anisotropy and energy equations. The properties of linear MHD waves and instability criteria are examined and numerical examples for the nonlinear evolutions of slow waves, fire-hose and mirror instabilities are shown. One significant result is that slow waves may develop not only mirror instability but also a new type of compressible fire-hose instability. Their corresponding nonlinear structures thus may exhibit anticorrelated density and magnetic field perturbations, a property used for identifying slow and mirror mode structures in the space plasma environment. The conditions for nonlinear saturation of both fire-hose and mirror instabilities are examined.

We report the first detection of polarization angle orthogonal jumps, a phenomenon previously only observed from radio pulsars, from a fast radio burst (FRB) source FRB 20201124A. We find three cases of orthogonal jumps in over 2000 bursts, all resembling those observed in pulsar single pulses. We propose that the jumps are due to the superposition of two orthogonal emission modes that could only be produced in a highly magnetized plasma, and they are caused by the line of sight sweeping across a rotating magnetosphere. The shortest jump timescale is of the order of 1 millisecond, which hints that the emission modes come from regions smaller than the light cylinder of most pulsars or magnetars. This discovery provides convincing evidence that FRB emission originates from the complex magnetosphere of a magnetar, suggesting an FRB emission mechanism that is analogous to radio pulsars despite a huge luminosity difference between two types of objects.

Understanding the jitter noise resulting from single-pulse phase and shape variations is important for the detection of gravitational waves using pulsar timing arrays. We present measurements of the jitter noise and single-pulse variability of 12 millisecond pulsars that are part of the International Pulsar Timing Array sample using the Five-hundred-meter Aperture Spherical radio Telescope. We find that the levels of jitter noise can vary dramatically among pulsars. A moderate correlation with a correlation coefficient of 0.57 between jitter noise and pulse width is detected. To mitigate jitter noise, we perform matrix template matching using all four Stokes parameters. Our results reveal a reduction in jitter noise ranging from 6.7% to 39.6%. By performing longitude-resolved fluctuation spectrum analysis, we identify periodic intensity modulations in 10 pulsars. In PSR J0030+0451, we detect single pulses with energies more than 10 times the average pulse energy, suggesting the presence of giant pulses. We also observe a periodic mode-changing phenomenon in PSR J0030+0451. We examine the achievable timing precision by selecting a subset of pulses with a specific range of peak intensity, but no significant improvement in timing precision is achievable.

As pattern recognition receptors (PRRs), C-type lectins (CTLs) have important roles in the recognition and clearance of pathogens by the innate immune system. In the present study, the first Cherax quadricarinatus CTL gene (designated CqCTL) was cloned and characterized. The complete cDNA sequence of CqCTL contained an open reading frame (ORF) of 543 bp, which encoded a protein of 180 amino acids. A carbohydrate recognition domain (CRD) containing four conserved cysteines (Cys48, Cys59, Cys76, Cys177) and the EPD (Glu80-Pro81-Asn82) and QPD (Gln146-Pro147-Asn148) motifs were identified in the deduced amino acid sequence of CqCTL. The deduced tertiary structure of CqCTL revealed two α helices，five β sheets and two disulfide bonds. CqCTL exhibited high similarity with previously identified CTLs from other species. The mRNA transcripts of CqCTL were ubiquitously detectable in all the tested tissues, with the highest expression level in hepatopancreas. These results provide useful information on the potential role of CqCTL in the innate immune system of C. quadricarinatus, and lay the foundation for further studies on the CTLs of crustacean.

Environmental stress can impair the survival, growth performance, and intestinal environment of shrimp. The objective of this study was to investigate the effect of glutathione (GSH) on the survival, growth performance, intestinal oxidation, microbiota, and histology of shrimp under hypoxia. Four treatments were used: (1) normoxia, (2) cyclic serious/medium hypoxia (CSMH), (3) CSMH and 75 mg kg−1 GSH, and (4) CSMH and 150 mg kg−1 GSH. White shrimp (Penaeus vannamei) in groups 3 and 4 were fed a commercial diet supplemented with 75 and 150 mg kg−1 GSH for a 28 day period, respectively, and they were cultured under CSMH (0.8 – 3.5 mg L−1 dissolved oxygen) for the last 14 days of the experiment. P. vannamei supplemented with 75 mg kg−1 GSH showed significantly improved survival and growth performance under CSMH compared with the CSMH condition alone. The dose of 75 mg kg−1 GSH completely eliminated overproduction of reactive oxygen species and malondialdehyde to suppress serious histopathological lesions and improve bacterial diversity and the relative abundance of beneficial bacteria, such as Rhodobacteraceae, thereby preventing pathogen (e.g., Vibrio) invasion in the intestine of shrimp under CSMH. However, the dose of 150 mg kg−1 GSH was excessive, as it led to serious impairment of survival and growth. These results indicate that 75 mg kg−1 GSH has the potential to control shrimp mortality and growth inhibition under CSMH in the shrimp farm setting.

Malectin is a newly discovered lectin of the endoplasmic reticulum (ER) that might be involved in innate immunity. Information about the roles of malectin in innate immunity is scarce. In the present study, a novel malectin gene (designated as CfMal) from the Zhikong scallop Chlamys farreri was identified and characterized. Sequence features, tissue distribution, and temporal expression profiles were investigated to infer the potential functions of CfMal in innate immunity. The complete cDNA sequence of CfMal comprised 1,111 bp and contained an open reading frame of 909 bp, which encoded 302 amino acid residues. A malectin domain and a transmembrane region were identified in the predicted protein sequence. CfMal mRNA transcripts were detectable in hemocytes, muscle, mantle, gill, hepatopancreas, and gonads. CfMal expression was highest in hemocytes. Stimulation with Vibrio splendidus increased CfMal expression in hemocytes, gill, and hepatopancreas. The mRNA transcripts of CfMal and three related genes, including binding immunoglobulin protein, heat shock protein 90 kDa β member 1 protein and ER degradation enhancing α-mannosidase like protein 1, increased in scallop hemocytes during an artificial ER-stress. Our results indicate that CfMal might not only be involved in ER-stress, but may also play a role in innate immunity of scallops.

Lysozymes act as key components of the innate immunity in invertebrates and play a pivotal role in early defense against invading microbe infection. In this study, an i-type lysozyme homology was identified and characterized in Zhikong scallop Chlamys farreri (designated as CfLyzI). The full-length cDNA sequence of CfLyzI contained a 702 bp open reading frame (ORF), which encoded a polypeptide of 233 amino acids and contained a typical destabilase function domain. The mRNA transcripts of CfLyzI were detectable in all the investigated tissues, including hemocytes, muscle, mantle, gill, hepatopancreas and gonad with the peak level in hemocytes. Being stimulated by Vibrio splendidus, the mRNA transcripts of CfLyzI significantly increased in hemocytes. The CfLyzI-suppressed scallops turned to be more susceptible to Vibrio. All these results indicated that CfLyzI acted as an efficient effector in the innate immunity and was also essential for hosts’ survival during Vibrio stimulation in Zhikong scallop.

The reactive oxygen species（ROS） generated by dual oxidases (Duox) play a role in innate immunity in many organisms. In this study, a 4,735 bp full-length cDNA of the Pacific white shrimp dual oxidase (LvDuox) gene was cloned; the sequence included an open reading frame of 4,497 bp, encoding a protein of 1,498 aa with a calculated mass of 173 kDa. Structural analysis revealed that LvDuox contains several domains. Homology analysis revealed that LvDuox exhibits 96.1%, 67.3% and 67.3% sequence identity with Marsupenaeus japonicas, Drosophila melanogaster and Acyrthosiphon pisum Duox, respectively. The mRNA transcripts of LvDuox were detected in all tested tissues. The mRNA expression of LvDuox was significantly induced in the midgut after Vibrio parahaemolyticus E1 (VPE1) stimulation. After the level of H2O2 in the midgut increased, expression of the superoxide dismutase and catalase genes in the midgut increased significantly. These results suggested that the LvDuox gene was upregulated in the midgut after the challenge by VPE1, and antioxidant genes were involved in the regulation of ROS in the shrimp midgut. LvDuox may therefore be a new target for intestinal disease research in the Pacific white shrimp.

The defender against apoptotic cell death 1 (DAD1) was a negative regulator to inhibit the apoptosis process. In the present study, a DAD1 gene (designated as CfDAD1) was identified in Zhikong scallop Chlamys farreri. Its full-length cDNA sequence of CfDAD1 contained a 342 bp open reading frame (ORF), which encoded a mature protein of 113 amino acids. A DAD domain was revealed from the deduced protein sequence of CfDAD1. The mRNA transcripts of CfDAD1 could be detectable in all the investigated tissues, including hemocytes, muscle, mantle, gill, hepatopancreas and gonad, among which the maximum expression level were found in hemocytes. Being infected with Vibrio splendidus, Staphylococcus aureus or Yarrowia lipolytica, the mRNA expression levels of CfDAD1 in hemocytes were all significantly up-regulated. Moreover, the apoptosis level of CfDAD1-suppressed group was significant higher than those of control groups. All these results indicated that CfDAD1 was efficient negative regulator of apoptosis and involved in the innate immune responses of scallop.

Astaxanthin (AST) is a beneficial dietary supplement in shrimp farming. However, the different effects of synthetic AST (S-Ast) and natural AST (N-Ast) on the postlarvae is unclear. These effects were compared by supplementation with a gradient of AST (0, 50, 70, 90, 140 ppm) for 35 days. Growth parameters including weight and length gain, carotenoid content, AST content and isomer composition, antioxidant capacity (superoxide dismutase, catalase, glutathione peroxidase), survival rate and mRNA expression levels for antioxidant enzymes in Litopenaeus vannamei postlarvae were measured. The results indicated that postlarvae given N-Ast had significantly higher growth performance and AST content. Although there were different ratios of AST optical isomers in the diets, there was a similar optical isomer content in juvenile shrimp. The cis/trans AST ratio and antioxidant enzyme (SOD and GPx) activities in N-Ast90 were the highest among all groups. Cumulative mortality in N-Ast90, N-Ast140 and S-Ast70 were significantly lower than in the control and N-AST50. The mRNA expression levels for the antioxidant enzymes (cMnSOD and GPx) also increased for N-Ast90-fed shrimp under stress conditions. These results suggest that an epimerase may exist in vivo and that an appropriate level of botanical AST in diets was approximately 90 ppm for L. vannamei postlarvae.

Heat shock proteins (HSPs) are the most abundant and ubiquitous soluble intracellular proteins which conserved phylogenetically in all living organisms from archaebacteria to humans. Recent research achievements indicated that HSP10s might not only be involved in the responses to environmental stresses, but also play a pivotal role in the host defenses mechanism. In the present study, a cDNA of 715 bp for the Pacific white shrimp Litopenaeus vannamei HSP10 (designated as LvHSP10) was cloned via rapid amplification of cDNA ends (RACE) technique. The complete cDNA sequence of LvHSP10 contained an open reading frame (ORF) of 309 bp, which encoded a protein of 102 amino acids. The protein sequence of LvHSP10 shared over 80 % similarity with previously identified HSP10s. There were a CPN10 domain and a chaperonins HSP10/CPN10 signature in the protein sequence of LvHSP10. The mRNA transcripts of LvHSP10 were constitutively expressed in all the tested tissues, including eyestalk, gill, gonad, heart, hemocytes, hepatopancreas, intestine, muscle, nerve and stomach, with the highest expression level in hepatopancreas. The mRNA expression profiles of LvHSP10 in hepatopancreas could be significantly induced by the stimulation of Vibrio parahaemolyticus, white spot syndrome virus (WSSV), and low and high pH challenge. These results provided useful information of the potential roles of LvHSP10 in the defense mechanism of shrimp against various biological stimulations and multiple environmental stresses.

The effect of cyclic serious/medium hypoxia stress in the presence of hypoxia environment on shrimp is not well explored. The survival, growth performance, osmoregulation gene expression, digestive enzyme activity, histology, and resistance against Vibrio parahemolyticus of the white shrimp Litopenaeus vannamei reared under conditions of cyclic serious/medium hypoxia (CSMH, 0.8 - 3.5 mg/L) versus normoxia (N, 6.4 - 7.5 mg/L) were investigated during an experimental period of 28 days. Consequently, the cumulative mortality rate of CSMH shrimp increased continuously. The weight gain percentage and length gain percentage of CSMH shrimp decreased continuously. The Na+/K+-ATPase, cytoplasmic carbonic anydrase (CAc), and glycosyl-phosphatidylinositol-linked carbonic anhydrase (CAg) transcripts in the gill of CSMH shrimp increased first and then returned to normal or decreased. The amylase, lipase, and trypsin activities in the hepatopancreas of CSMH shrimp decreased continuously. The hepatopancreas of CSMH shrimp showed histopathological lesions in a time-dependent manner. In the V. parahaemolyticus immersion challenge test, the mortality rate of CSMH shrimp increased continuously. Therefore, cyclic serious/medium hypoxia could reduce survival and growth performance of L. vannamei during long-term exposure, which was resulted from broken osmoregulation mechanism of the gill, and suppressed digestive enzyme activities of the hepatopancreas caused by growing histopathological lesions. Meanwhile, cyclic serious/medium hypoxia would probably lead to outbreak of infectious diseases in the shrimp farming.

We propose a new method for the multiple attribute decision making problem. In this problem, the decision making information assembles multiple source data. Two main advantages of this proposed approach are that (i) it provides a data fusion technique, which can efficiently deal with the multisource decision making information; (ii) it can produce the degree of credibility of the entire decision making. The proposed method performs very well especially for the scenario that there exists conflict among the multiple source information. Finally, a traffic engineering example is given to illustrate the effect of our method.

Fabrication of InGaAlAs MQW buried heterostructure (BH) lasers by narrow stripe selective MOVPE is demonstrated in this paper. High quality InGaAlAs MQWs were first grown by narrow stripe selective MOVPE without any etching process and assessed by analysing the cross sections and PL spectrums of the InGaAlAs MQWs. Furthermore, BHs were fabricated for the InGaAlAs MQW lasers by a developed unselective regrowth method, instead of conventional selective regrowth. The InGaAlAs MQW BH lasers exhibit good device characteristics, with a high internal differential quantum efficiency of 85% and a low internal loss of 6.7?cm?1. Meanwhile, narrow divergence angles of the far field pattern are obtained for the fabricated lasers. [ABSTRACT FROM AUTHOR]

The design and basic characteristics of a strained InGaAsP–InP multiple-quantum-well (MQW) DFB laser monolithically integrated with an electroabsorption modulator (EAM) by ultra-low-pressure (22 mbar) selective-area-growth (SAG) MOCVD are presented. A fundamental study of the controllability and the applicability of band-gap energy by using the SAG method is performed. A large band-gap photoluminescence wavelength shift of 88 nm was obtained with a small mask width variation (0–30 µm). The technique is then applied to fabricate a high performance strained MQW EAM integrated with a DFB laser. The threshold current of 26 mA at CW operation of the device with DFB laser length of 300 µm and EAM length of 150 µm has been realized at a modulator bias of 0 V. The devices also exhibit 15 dB on/off ratio at an applied bias voltage of 5 V. [ABSTRACT FROM AUTHOR]

A general formulation is proposed for electrostatic solitons in multicomponent plasmas consisting of one cold species described by the fluid model and multiple hot components described by the kinetic equation. For hot species two types of generalized velocity distributions are adopted: the kappa function and the highly nonthermal distribution with two free parameters which incorporate the widely used nonthermal distribution proposed by Cairns et al (1995 Geophys. Res. Lett. 22 2709) as a special limit. The general expressions for the KdV equations and the Sagdeev potential, as well as the conditions for electrostatic solitons with positive or negative polarity, are derived, which may give rise to various solutions for acoustic solitons in multicomponent plasmas with generalized nonthermal velocity distributions. [ABSTRACT FROM AUTHOR]

A 1.55 µm InGaAsP-InP two-section DFB laser with a variable ridge width has been fabricated. Self-pulsations with frequencies around 3 GHz and 40 GHz are observed. The pulsation mechanisms related to the two frequencies are discussed and the tunability of generated self-pulsations is studied. [ABSTRACT FROM AUTHOR]