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Rice blast is an essential factor affecting rice yield and quality, which is caused by

Terminal or interstitial deletion of chromosome 2q is rarely reported but clinically significant, which can result in developmental malformations and psychomotor retardation in humans. In the present study, we analyzed this deletion to comprehensively clarify the relationship between phenotype and microdeletion region.We collected clinical records of the fetus and summarized patient symptoms. Subsequently, genomic DNA was extracted from fetal tissue or peripheral blood collected from parents. In addition, whole-exome sequencing (WES) and copy number variation sequencing (CNV-seq) were performed.The fetus presented a previously unreported interstitial deletion of 2q24.3-q32.1. WES and CNV-seq revealed a de novo 18.46 Mb deletion at 2q24.3-q32.1, a region involving 94 protein-coding genes, including HOXD13, MAP3K20, DLX1, DLX2, SCN2A, and SCN1A. The fetus had upper and lower limb malformations, including camptodactyly and syndactyly, along with congenital cardiac defects.Herein, we report a fetus with a novel microdeletion of chromosome 2q24.3-q32.1, likely a heterozygous pathogenic variant. Haploinsufficiency of HOXD13 might be related to limb deformity in the fetus.

Aerobic exercise is effective in alleviating mood symptoms while the mechanism is poorly understood. There are limited clinical trials that investigated the effect of exercise on the anterior cingulate cortex (ACC), a key brain region involved in mood regulations, in adolescents with subthreshold mood syndromes. This randomized controlled trial (RCT) of aerobic exercise was undertaken in a middle school in Guangzhou, China. Participants were adolescents aged 12–14 with subthreshold mood syndromes including depressive and manic symptoms and were randomly assigned to an aerobic exercise intervention or a psychoeducation control group. Participants in the exercise group received moderate-intensity exercise intervention, consisting of 30 mins running, 4 days per week for 3 months. The primary outcome in this study was structural changes in the ACC from baseline to post intervention. The trial was registered with ClinicalTrial.gov (NCT03300778). Of 56 participants who met the criteria for subthreshold mood syndromes, 39 (41.03% males) had complete MRI data, with 20 and 19 subjects in the exercise and control group, respectively. At baseline, demographic information (e.g., age and sex), clinical symptoms, and the gray matter volume and cortical thickness of ACC were matched between the two groups. After 12 weeks of treatment, participants in the exercise group displayed increased gray matter volume of the left rostral ACC (F1,30 = 5.73, p = 0.02) and increased cortical thickness of the right rostral ACC (F1,30 = 7.83, p = 0.01) when compared with the control group. No significant differences were found for caudal ACC cortical thickness and gray matter volume. Our data demonstrate that 12-week, moderate-intensity aerobic exercise can induce structural changes in the rostral ACC in adolescents with subthreshold mood syndromes.

Magnaporthe oryzae (M. oryzae) is a typical cause of rice blast in agricultural production. Isobavachalcone (IBC), an active ingredient of Psoralea corylifolia L. extract, is an effective fungicide against rice blast. To determine the mechanism of IBC against M. oryzae, the effect of IBC on the metabolic pathway of M. oryzae was explored by transcriptome profiling. In M. oryzae, the expression of pyruvate dehydrogenase E1 (PDHE1), part of the tricarboxylic acid (TCA cycle), was significantly decreased in response to treatment with IBC, which was verified by qPCR and testing of enzyme activity. To further elucidate the interactions between IBC and PDHE1, the 3D structure model of the PDHE1 from M. oryzae was established based on homology modeling. The model was utilized to analyze the molecular interactions through molecular docking and molecular dynamics simulation, revealing that IBC has π-π stacking interactions with residue TYR139 and undergoes hydrogen bonding with residue ASP217 of PDHE1. Additionally, the nonpolar residues PHE111, MET174, ILE 187, VAL188, and MET250 form strong hydrophobic interactions with IBC. The above results reveal that PDHE1 is a potential target for antifungal agents, which will be of great significance for guiding the design of new fungicides. This research clarified the mechanism of IBC against M. oryzae at the molecular level, which will underpin further studies of the inhibitory mechanism of flavonoids and the discovery of new targets. It also provides theoretical guidance for the field application of IBC.

The rice blast disease caused by the fungus Magnaporthe grisea is one of the most devastating rice diseases, but there is no effective fungicide toward chitinase which is a key enzyme of M. grisea....

Background Current knowledge on objective and specific neural markers for bipolar risk and resilience-related processes is lacking, partly due to not subdividing high-risk individuals manifesting different levels of subclinical symptoms who possibly possess different levels of resilience. Methods We delineated grey matter markers for bipolar illness, genetic high risk (endophenotype) and resilience, through comparing across 42 young non-comorbid bipolar patients, 42 healthy controls, and 72 diagnosis-free, medication-naive high-genetic-risk individuals subdivided into a combined-high-risk group who additionally manifested bipolar risk-relevant subsyndromes (N = 38), and an asymptomatic high-risk group (N = 34). Complementary analyses assessed the additional predictive and classification values of grey matter markers beyond those of clinical scores, through using logistic regression and support vector machine analyses. Results Illness-related effects manifested as reduced grey matter volumes of bilateral temporal limbic-striatal and cerebellar regions, which significantly differentiated bipolar patients from healthy controls and improved clinical classification specificity by 20%. Reduced bilateral cerebellar grey matter volume emerged as a potential endophenotype and (along with parieto-occipital grey matter changes) separated combined-high-risk individuals from healthy and high-risk individuals, and increased clinical classification specificity by approximately 10% and 27%, respectively, while the relatively normalized cerebellar grey matter volumes in the high-risk sample may confer resilience. Limitations The cross-validation procedure was not performed on an independent sample using independently-derived features. The BD group had different age and sex distributions than some other groups which may not be fully addressable statistically. Conclusions Our framework can be applied in other measurement domains to derive complete profiles for bipolar patients and at-risk individuals, towards forming strategies for promoting resilience and preclinical intervention.

In this study, we investigated the association between bipolar I disorder (BDI) and between cognitive deficits therein and SNPs in GABAergic receptor genes. The sample comprised 477 patients with BDI and 438 healthy controls, with three neurocognitive tests being administered in 123 patients and 164 controls. For three SNPs, rs505474, rs1398175, and rs4868029 in the GABRA2, GABRA4, and GABRP genes, respectively, their allele frequencies were significantly different between patients and controls (Bonferroni-adjusted p = values 3.84 × 10-4 , 9.92 × 10-3 , and 1.22 × 10-2 , respectively). Four haplotypes were significantly associated with BDI (TA and AG for rs3815762 and rs4868029 in GABRP, GG for rs11636988 and rs8024256 in GABRB3 and GAGG for rs2197414, rs4921195, rs13188991, and rs11956731 in GABRA6, with p values of 0.0038, 0.044, 0.0176, and 0.0267, respectively, on 10,000 permutations). Furthermore, the SNP (rs2912585) within 250 kb upstream of the GABRB3 gene displayed a strong association with the Tower of Hanoi (TOH) executive time in the patient group (p = 2.844 × 10-6 ). One other SNP (rs754661), which is located at the intronic region of the same gene, was associated with the global trait of the executive function and post hoc analysis showed significant SNP by group effect (p = 0.0094). Our study supports previous findings that GABAA receptor genes are associated with bipolar disorder; it also suggests that the GABAA genes, especially the GABRB3 gene, might play a role in the executive function deficit in bipolar disorder, although future replication with a larger sample size is needed.

Aberrant structural (diffusion tensor imaging [DTI]) and resting‐state functional magnetic resonance imagining connectivity are core features of bipolar disorder. However, few studies have explored the integrity agreement between structural and functional connectivity (SC–FC) in bipolar disorder. We examine SC connectivity coupling index whether could potentially provide additional clinical predictive value for bipolar disorder spectrum disorders besides the intramodality network measures. By examining the structural (DTI) and resting‐state functional network properties, as well as their coupling index, among 57 euthymic bipolar disorder patients (age 13–28 years, 18 females) and 42 age‐ and gender‐matched healthy controls (age 13–28 years, 16 females), we found that compared to controls, bipolar disorder patients showed increased structural rich‐club connectivity as well as decreased functional modularity. Importantly, the coupling strength between structural and functional connectome was decreased in patients compared to controls, which emerged as the most powerful feature discriminating the two groups. Our findings suggest that structural–functional coupling strength could serve as a valuable biological trait‐like feature for bipolar disorder over and above the intramodality network measures. Such measure can have important clinical implications for early identification of bipolar disorder individuals, and inform strategies for prevention of bipolar disorder onset and relapse.

The effects of intrahepatic cholestasis of pregnancy (ICP) on hepatic function, changes of inflammatory cytokines and fetal outcomes were studied. In total, 663 pregnant women admitted to Daqing Longnan Hospital from July 2016 to December 2017 were selected. There were, 40 cases with ICP enrolled in the observation group, and 40 normal pregnant women were recruited in the normal group. They were also grouped according to hepatic function and inflammatory cytokines, with 40 cases in each group. Neonatal Apgar scores were recorded. The correlations of serum cholylglycine (CG) in pregnant women with umbilical artery systolic-to-diastolic (S/D) ratio in the third trimester of pregnancy, the alanine aminotransferase level, the high-sensitivity C-reactive protein (hs-CRP) level, neonatal Apgar score and gestational week were analyzed. The birth weight in the observation group was lighter than that in the normal group (P

The rice blast disease caused by the fungus

Background The oxidative stress hypothesis proposed to explain bipolar I disorder (BD I) pathogenesis has gained growing attention based on its association with cognitive impairment. The aim of the present study was to explore the association of the methionine sulfoxide reductase A (MsrA) gene with BD I as well as executive functions of BD I patients. Methods A total of 44 tagging single-nucleotide polymorphisms within the MsrA gene were selected to analyze gene association with BD I in 375 BD I patients and 475 controls in a Han Chinese population. The association of MsrA haplotypes with executive functions was analyzed in 157 clinically stable BD I patients and 210 controls. Results Allele frequencies of the rs4840463 polymorphism were significantly different between BD I patients and controls, and between patients with psychotic symptoms and controls. BD I patients performed more poorly in 11 of the 13 neurocognitive measurements compared with controls. Three MsrA haplotypes showed significant associations with different executive functions. Limitations The limited sample size requires a cautious conclusion, and further comprehensive approaches are needed to explore the mechanism of MsrA's effect on BD I. Conclusions The rs4840463 polymorphism in the MsrA gene may be associated with the increased risk of BD I in a Chinese population. The association of MsrA haplotypes with executive functions indicated that MsrA is associated with executive function defects in BD I patients.

Aberrant structural (diffusion tensor imaging, DTI) and resting-state functional (rsfMRI) connectivity are core features of bipolar disorder (BD). However, few studies have explored the integrity agreement between structural and functional connectivity in BD (SC-FC coupling). Such SC-FC coupling index could potentially provide additional clinical predictive value for BD spectrum disorders besides the intra-modality network measures. Thus, we examined the structural (DTI) and resting-state functional network properties, as well as their coupling index, among 57 euthymic BD patients (age 13-28 years, 18 females) and 42 age- and gender-matched healthy controls (age 13-28 years, 16 females). We found that compared to controls, BD patients showed increased structural rich club connectivity as well as decreased functional modularity. Importantly, the coupling strength between structural and functional connectome was decreased in BD patients compared to controls, which emerged as the most powerful feature discriminating the two groups. Our findings suggest that structural-functional coupling strength could serve as a valuable biological trait marker for bipolar disorder over and above the intra-modality network measures. Such measure can have important clinical implications for early identification of BD individuals, and inform strategies for prevention of BD onset and relapse. Funding: This study was funded by the National Natural Science Foundation of China (NSFC: 81471375,81671347), Guangdong Engineering Technology Research Center for Translational Medicine of Mental Disorders (201805010009), and Guangzhou Municipal Psychiatric Disease Clinical Transformation Laboratory (201805010009), which had no further role in study design, in the collection, analysis and interpretation of data, in the writing of the report, and in the decision to submit the paper for publication. Declaration of Interest: We declare no competing interests. Ethical Approval: This study was approved by the Institutional Review Board of the Guangzhou Brain Hospital.

To determine the correlation among the polymorphisms of dopamine receptor genes, cognitive function of Bipolar disorder (BD) patients, and BD.Twenty-three Single Nucleotide Polymorphisms (SNPs) of dopamine receptor genes were genotyped using Illumina GoldenGate genotyping assay in 375 patients with bipolar I disorder (BD-I) (patients group) and 475 healthy controls (control group). Cognitive function tests were performed in 158 patients who were clinically stable and 307 healthy controls who were matched with the patients in age, sex, and education.The allele frequencies of rs3758653 in the promoter region of the DRD4 gene were significantly different between patients group and control group (χ(2)=9.386, Corrected P=0.046). This significant difference was also observed between BD-I patients with psychotic symptoms and healthy controls (χ(2)=9.27, Corrected P=0.049). Patients with BD-I performed significantly worse than healthy controls in all cognitive domains (p0.01) except TMTA errors and illegal time. Significant interactions between polymorphisms of rs5326 in DRD1 gene and phenotype (affected or unaffected with BD-I) were found in non-perseverative errors (β=3.20 and Corrected P=0.0034) on the Wisconsin Card Sorting Test (WCST). The allele of this SNP denoted the positive effect on the WCST non-perseverative errors in BD-I patients group (β=2.80 and Corrected P=0.017). The genotypic association analyses also supported the findings (F=4.24 and P=0.007), but this effect was not found in controls.The sample size was relatively small and the SNP coverage was limited, making it very important to be cautious when drawing a conclusion.DRD4 gene may play an important role in psychotic symptomatology rather than in unique diagnosis, BD, for example. A genetic association exists between DRD1 gene and impaired cognition in BD.

Background The reason why it is difficult to identify susceptibility genes attributed to bipolar disorder (BPD) is the phenotypic heterogeneity. The use of endophenotypes has been advocated as one possible strategy to discovery cause variants of BPD. Methods A total of 164 patients with BPD and 164 matched controls were employed in the present research. Fifty-two single nucleotide polymorphisms (SNPs) within the genes in serotonin pathway were selected for genotyping using the GoldenGate genotyping assay. All participants completed three neurocognitive tests including the tower of Hanoi (TOH), the Wisconsin card sorting test (WCST) and Trail making tests (TMTA and TMTB-M). Results Patients with BPD demonstrated a wide range of deficits in mental activities of attention and speed of information processing, and executive function. Significant interactions between rs2760347 in 5HTR2A gene and diagnosis were found for the executive time of TOH, with β = 11.82 and P = 0.002 (adjusted P = 0.03 after Bonferroni correction). Conclusions Cognitive impairments existing in BPD may be particularly notable in certain domains of attention and executive function, and 5HTR2A gene may be involved in modulating executive function of BP-I patients.

Rhizobacteria is a prosperous for promoting plant growth for the superiority of reducing environmental damages. Two Strains of Chlorobium limicola and Rhodopseudomonas palustris were supplied in the experiment as potential inoculants for cucumber. Significant enhancement of the availability of macronutrient elements N, P and K were observed in soil, and further improvement on the uptake of them was also obtained in cucumber plants. Accumulation of essential micronutrients of Fe and Zn were detected both in roots and in shoots. The two stains increased chlorophyll and carotinoid synthesis, plant height, stem diameter, wet weight and dry weight. Various dose has significantly effect on plant growth stimulation, C. Limicola with 10 7 cells mL -1 and R. Palustris with 10 8 cells mL -1 seem to be better on the whole.

As the perpendicular recording writer keeps scaling down to improve recording areal density and data rate throughput, the off-track performance of the writer, including both adjacent track erasure and wide area adjacent track erasure, becomes one of the key challenges in hard disk drives. Understanding writer erasure locations and mechanisms is critical. In this paper, stationary footprint technique is used to study various perpendicular writer designs. The asymmetric responses of two side shields in wrapped-around shielded writer are observed, which agree well with micromagnetic modeling results. The impacts of asymmetric side shields on cross track gradient and adjacent track erasure were qualitatively verified. The hot spot locations and mechanisms of wide area track erasure have been investigated. The impacts of recording media and recording reader in stationary footprint measurement are also discussed.

In order to enhance the surface wear resistance and nitrogen diffusion during plasma treatment, orthopedic NiTi alloy is subjected to surface mechanical attrition treatment (SMAT) and a nanocrystalline and partial amorphous structure is fabricated in the surface layer. It is found that hardness in the surface layer is notably improved. The corrosion behavior is systematically studied in a 0.9% NaCl physiological solution by electrochemical methods. Potentiodynamic polarization measurements indicate that the corrosion resistance of SMAT NiTi with the surface nanocrystalline and partial amorphous structure is significantly enhanced compared to the bare NiTi with coarse grains. Both corrosion potential (Ecorr) measurements and electrochemical impedance spectroscopy (EIS) reveal that a passive oxide layer is readily formed on the SMAT NiTi during early immersion in the 0.9% NaCl solution. When the passive oxide layer has stabilized after long exposure in the 0.9% NaCl solution, corrosion induced by Cl− begins to degrade the passive oxide film. The observed corrosion behavior of SMAT NiTi is considered to be associated with the surface nanocrystalline and amorphous structure.

A modified test of the fifth harmonic measurement for nonlinear transition shift (NLTS) is used to study the influence of the head field properties on some parametric data and signal-to-noise ratio (SNR) performances in perpendicular recording. Particularly, the NLTS properties of two different writer head designs were evaluated in connection with their recording performances. It was revealed that the NLTS properties are sensitive to both the head field strength and head field gradient and thus affect the SNR and bit error rate (BER) performances strongly, especially at high linear density.

As the magnetic moment of soft under layer (SUL) decreases, the magnetic saturation during the write process becomes severe. It induces some partial erasures in the media write pattern and results in poor write performance such as an output roll-off and signal-to-noise ratio degradation. This erasure is due to the head field longitudinal component at the write gap after the transition writing in the trailing shielded pole perpendicular recording head. In case the SUL has low magnetic moment and high write current is inputted, erasure bubble appears next to the write bubble because the head field perpendicular component switches from positive to negative in the polarity. But the erasure appears even without the negative perpendicular field, and the longitudinal head field of the write gap is dominant for the erasure.

With the continuous push for high areal density, the conventional trailing shield perpendicular writer design faces an increasing challenge in maintaining sufficient writability while scaling down the dimensions of the write pole and the shield. In this work, we investigate an improved trailing shield design with the tapered write gap (TWG). It has been found that the TWG design has two unique recording characteristics that enable better extendibility: 1) flux concentration and 2) self-compensation. Both modeling and experimental results show that the TWG design has superior dynamic performance (DP) than conventional trailing shield design, while the sigma of DP parameters induced by the wafer/back-end variations is reduced.

Summary form only given. We investigated the requirements for a single-pole type (SPT) perpendicular write head and found that certain design trade-offs must be made with respect to the recording media. It is shown through finite element analysis (FEA) that in order to get a high write field, which is what makes perpendicular recording advantageous, a short pole length and small separation distance from the air-bearing surface (ABS) to soft magnetic underlayer (SMUL) are required. However, with a shorter pole length, field gradients deteriorate and the background field increases leading to poorly written bits due to magnetic reversal. The gradients can be improved at the expense of maximum write field. Further complicating the perpendicular write system is non-ideal media. Variations in the media anisotropy enhance the effects of the gradients and background fields. Micromagnetic simulations were carried out for two designs to show these detrimental effects.

To assess the association of neural development-related genes LIS1and TSNAX with bipolar disorder in a Chinese Han population.Three hundred and eight five patients (including 188 males and 197 females) from Guangzhou Brain Hospital with bipolar disorder meeting the Diagnostic and Statistic Manual of Bipolar Disorder (BDI) (Fourth Edition) criteria and 475 healthy controls from the local community were recruited. Ten single nucleotide polymorphisms (SNPs) of the LIS1 and TSNAX genes were genotyped by GoldenGate genotyping assay on an Illumina Beadstation 500 machine. Association analyses of SNPs and haplotypes were performed with Plink 1.07 software.Analysis of the total sample has failed to find any association of SNP or haplotype of the two genes with BDI (P0.05). When patients were divided into subgroups with or without psychotic symptom, no significant association of the two genes was found with psychotic BDI or non-psychotic BDI (P0.05). No significant association was found between any SNP and haplotype of two genes and female BDI or male BDI, nor were significant association found between age of onset and LIS1 and TSNAX gene polymorphisms.Our results indicated that LIS1 and TSNAX genes are not associated with susceptibility to bipolar I disorder in Chinese Han population.

We present a micromagnetic and analytical analysis of double layer media with antiferromagnetic exchange coupling. It has been found that in order to achieve good recording performance, strong interlayer exchange coupling and large thickness ratio are desired. When the thickness of the bottom layer is small, thermal activation assists the bottom layer to switch, which requires a smaller interlayer exchange coupling constant. Thermal stability of double layer AFC media has also been investigated in comparison to single layer media in the case of strong and weak interlayer exchange coupling.

In this paper, we present a combined experimental and micromagnetic simulation study of the recording, noise and position error signal characteristics in patterned thin film media. The medium is patterned with a focused ion beam etching technique on typical present thin film disks. It is found the transition noise is completely absent in the patterned thin film media. Comparing with continuous thin film media, the medium noise is reduced to the level of noise at saturation remnant state and is no longer density-dependent. With the elimination of transition noise, the signal-to-medium-noise ratio will be sufficient at very narrow track widths without further reduction of grain size. A slight increase of intergranular exchange coupling will have little impact on medium noise, but enhance thermal magnetic stability of the medium. Down track orientation of the crystalline easy axes will further improve the recording performances. Position error signal patterns in patterned media can be more versatile and significantly more effective and efficient.

This paper presents a numerical analysis of adjacent track erasure (ATE) when operating wrapped-around shielded perpendicular magnetic recording (PMR) heads. Micromagnetic finite element modeling was used to investigate the magnetization dynamics in a PMR writer including a soft underlayer, and the resultant magnetic field in the recording layer. It is found that the ATE-field is an asymmetric and localized return field. Such an asymmetry is determined by the directions of both the magnetization in the pole tip and the initial magnetization in the WAS. The ATE-field is located near the corner and the inner edge of one side-shield. It is also found that the ATE-field remains strong for most of the time during write-field switching.

Background Based on the function of neuregulin 1 (NRG1) in neurodevelopment, susceptibility to bipolar disorder presumably involves this gene. The 3′ region of NRG1 contains the majority of the coding exons, and transcripts from this region encode 8 of the 9 known NRG1 isoforms; therefore, this region is likely to be predominant versus the 5′ region in terms of their relative contributions to NRG1 function. We investigated the association between the 3′ region of the NRG1 gene and bipolar I disorder (BPI) in the Chinese Han population and performed further analyses depending on the presence or absence of psychotic features. Methods A total of 385 BPI patients and 475 healthy controls were recruited for this study. Thirty tag single nucleotide polymorphisms (SNPs) across the 3′ region of the NRG1 gene were genotyped for allelic and haplotypic associations with BPI and subgroups with psychotic features (BPI-P) or without psychotic features (BPI-NP). Results Individual marker analysis showed that 2 SNPs (rs12547858 and rs6468121) in this region were significantly associated with BPI. Moreover, subgroup analyses showed significant but marginal associations of rs6468121 with BPI-P and rs3757933 with BPI-NP. Haplotype analyses showed that 6 haplotypes were associated with BPI only. Limitations The sample size was relatively small. The investigated tag SNPs only represented 83% of the information on the targeted region. There might be a retrospective bias in the subgroup analyses. Conclusion The results suggest that the 3′ region of the NRG1 gene plays a role in BPI susceptibility in the Chinese Han population. In addition, the preliminary results show that BPI with psychotic features and BPI without psychotic features may constitute different sub-phenotypes; however, this finding should be confirmed in a larger population sample.

Serotonin plays an important role in mood regulation, but the involvement of serotonin pathway genes in the development of bipolar I disorder (BP-I), a mood disorder, is not clear. We selected 21 single-nucleotide polymorphisms (SNPs) within the HTR2A gene, 8 within the SLC6A4 gene and 23 within the TPH2 gene for genotyping using the GoldenGate genotyping assay. A total of 375 patients with BP-I and 475 normal controls were recruited. Two out of 21 SNPs (rs1475196 and rs9567747) in the HTR2A gene and 1/23 SNPs (rs17110566) in the TPH2 gene were significantly associated with BP-I, both genotype-wise and allele-wise. Furthermore, a specific haplotype in the HTR2A gene showed a significant association with BP-I. Our results indicate that the HTR2A and TPH2 genes in the serotonin pathway play important roles in susceptibility to BP-I.

The effect of second-order uniaxial anisotropy energy K/sub 2/ on thermal stability and writability of perpendicular media has been studied. Due to the high orientation of crystalline easy axes, both energy barrier and dynamic coercivity of perpendicular media increases with K/sub 2/. With relatively more increase in energy barrier, improvement of the tradeoff between thermal stability and writability can be achieved by increasing K/sub 2/. The field angle dependence with nonzero K/sub 2/ is also quantitatively investigated.

Summary form only given. One of the key advantages of single-pole (SP) head/media with magnetic soft underlayer (SUL) perpendicular recording system is its ability to obtain larger write field in the media than that in longitudinal recording. However, such advantage is diminished as the dimension of the pole tip is reduced to increase areal recording density. In this work, the effects of head field rise time and media damping constant on switching field and switching time are investigated through micromagnetic simulations.

Micromagnetic modeling is used to study the recording characteristics of patterned polycrystalline thin film media. The dependence of medium noise on medium microstructure is quantitatively investigated. It is found that for patterned media the medium noise arises from magnetization fluctuation at the saturate remanent state. Forming the orientation preference of anisotropy easy axes along the recording direction significantly reduces the medium noise of patterned media. Large bit aspect ratio is preferred to reduce medium noise. For patterned media, a moderate exchange coupling helps to maintain medium thermal stability and the medium noise it introduces is negligible.

We have studied the magnetization configuration of various pole-tip design perpendicular magnetic recording heads by using finite element method (FEM) based micromagnetic simulation. Taper pole has larger head field of 13%–25% than nontaper pole and delivers better gradient because the magnetization of the main pole becomes more perpendicular to the air bearing surface (ABS) and an increase in magnetic charge is observed not only at the ABS but also at the slope region. Side shield has less fringing field in the cross-track direction but the field profile is not as simple as the conventional FEM result. The side shield has a complex domain configuration around the edge, which is difficult to switch in polarity via write current excitation, differing from the trailing-shield situation. The magnetic charge of the side-shield wall induces off-track peaks of the fringing field, and so it must be minimized to optimize the side-shield structure.

In this article, we present a combined analytical analysis along with micromagnetic simulations on the thermal stability of double layer longitudinal media with antiferromagnetic exchange coupling (AFC). The thermal stability enhancement in double layer AFC media is characterized quantitatively and comparisons with the performance of conventional single layer longitudinal media are made. It has been found that the thermal stability enhancement of the AFC media over a single layer media with the same medium coercivity can be achieved by optimizing the interlayer exchange coupling. The effective grain volume gain is found to be approximately V1+0.4V2, where V1 and V2 are the grain volumes of the top and bottom layers, respectively. Increasing V2 requires a larger interlayer exchange coupling constant.

A micromagnetic model for studying recording and noise characteristics in perpendicular media with a soft magnetic underlayer has been developed. The single pole head and soft magnetic underlayer are modeled with two-dimensional meshes and the medium is modeled with a three-dimensional granular structure. Utilizing the model, the dependence of recording characteristics on a medium microstructure, especially the intergranular exchange coupling, and write field is investigated.