Two-photon spin injection in semiconductors

A comparison is made between the degree of spin polarization of electrons excited by one- and two-photon absorption of circularly polarized light in bulk zincblende semiconductors. Time- and polarization-resolved experiments in (001)-oriented GaAs reveal an initial degree of spin polarization of 49% for both one- and two-photon spin injection at wavelengths of 775 and 1550 nm, in agreement with theory. The macroscopic symmetry and microscopic theory for two-photon spin injection are reviewed, and the latter is generalized to account for spin-splitting of the bands. The degree of spin polarization of one- and two-photon optical orientation need not be equal, as shown by calculations of spectra for GaAs, InP, GaSb, InSb, and ZnSe using a 14x14 k.p Hamiltonian including remote band effects. By including the higher conduction bands in the calculation, cubic anisotropy and the role of allowed-allowed transitions can be investigated. The allowed-allowed transitions do not conserve angular momentum and can cause a high degree of spin polarization close to the band edge; a value of 78% is calculated in GaSb, but by varying the material parameters it could be as high as 100%. The selection rules for spin injection from allowed-allowed transitions are presented, and interband spin-orbit coupling is found to play an important role.Comment: 12 pages including 7 figure

Significant associations of PAI-1 genetic polymorphisms with osteonecrosis of the femoral head

<p>Abstract</p> <p>Background</p> <p>The pathogenesis of osteonecrosis of the femoral head (ONFH) has been implicated in hypofibrinolysis and blood supply interruption. Previous studies have demonstrated that decreased fibrinolytic activity due to elevated plasminogen activator inhibitor-1 (PAI-1) levels correlates with ONFH pathogenesis. The -675 4G/5G single nucleotide polymorphism (SNP rs1799889) in the PAI-1 gene promoter is associated with PAI-1 plasma level. We investigated whether rs1799889 and two other SNPs of the PAI-1 gene (rs2227631, -844 G/A in the promoter; rs11178, +10700 C/T in the 3'UTR) are associated with increased ONFH risk.</p> <p>Methods</p> <p>Three SNPs in PAI-1 were genotyped in 206 ONFH patients and 251 control subjects, using direct sequencing and a TaqMan^®5' allelic discrimination assay. We performed association analysis for genotyped SNPs and haplotypes with ONFH.</p> <p>Results</p> <p>The 4G allele of rs1799889, A allele of rs2227631, and C allele of rs11178 were significantly associated with increased ONFH risk (p = 0.03, p = 0.003, and p = 0.002, respectively). When we divided the population according to gender, an association between the three SNPs and increased risk of ONFH was found only in men. In another subgroup analysis based on the etiology of ONFH, rs2227631 (A allele) and rs11178 (C allele) in the idiopathic subgroup (p = 0.007 and p = 0.021) and rs1799889 (4G allele) and rs11178 (C allele) in the alcohol-induced subgroup (p = 0.042 and p = 0.015) were associated with increased risk of ONFH. In addition, a certain haplotype (A-4G-C) of PAI-1 was also significantly associated with ONFH (p < 0.001).</p> <p>Conclusion</p> <p>Our findings demonstrated that three SNPs (rs1799889, rs2227631, and rs11178) of the PAI-1 gene were associated with ONFH risk. This study also suggests that PAI-1 SNPs may play an important role in ONFH.</p

HGF-Transgenic MSCs Can Improve the Effects of Tissue Self-Repair in a Rabbit Model of Traumatic Osteonecrosis of the Femoral Head

BACKGROUND: Osteonecrosis of the femoral head (ONFH) is generally characterized as an irreversible disease and tends to cause permanent disability. Therefore, understanding the pathogenesis and molecular mechanisms of ONFH and developing effective therapeutic methods is critical for slowing the progress of the disease. METHODOLOGY/PRINCIPAL FINDINGS: In this study, an experimental rabbit model of early stage traumatic ONFH was established, validated, and used for an evaluation of therapy. Computed tomography (CT) and magnetic resonance (MR) imaging confirmed that this model represents clinical Association Research Circulation Osseous (ARCO) phase I or II ONFH, which was also confirmed by the presence of significant tissue damage in osseous tissue and vasculature. Pathological examination detected obvious self-repair of bone tissue up to 2 weeks after trauma, as indicated by revascularization (marked by CD105) and expression of collagen type I (Col I), osteocalcin, and proliferating cell nuclear antigen. Transplantation of hepatocyte growth factor (HGF)-transgenic mesenchymal stem cells (MSCs) 1 week after trauma promoted recovery from ONFH, as evidenced by a reversed pattern of Col I expression compared with animals receiving no therapeutic treatment, as well as increased expression of vascular endothelial growth factor. CONCLUSIONS/SIGNIFICANCE: These results indicate that the transplantation of HGF-transgenic MSCs is a promising method for the treatment for ONFH and suggest that appropriate interference therapy during the tissue self-repair stage contributes to the positive outcomes. This study also provides a model for the further study of the ONFH etiology and therapeutic interventions

Salvianolic Acid B Prevents Bone Loss in Prednisone-Treated Rats through Stimulation of Osteogenesis and Bone Marrow Angiogenesis

Glucocorticoid (GC) induced osteoporosis (GIO) is caused by the long-term use of GC for treatment of autoimmune and inflammatory diseases. The GC related disruption of bone marrow microcirculation and increased adipogenesis contribute to GIO development. However, neither currently available anti-osteoporosis agent is completely addressed to microcirculation and bone marrow adipogenesis. Salvianolic acid B (Sal B) is a polyphenolic compound from a Chinese herbal medicine, Salvia miltiorrhiza Bunge. The aim of this study was to determine the effects of Sal B on osteoblast bone formation, angiogenesis and adipogenesis-associated GIO by performing marrow adipogenesis and microcirculation dilation and bone histomorphometry analyses. (1) In vivo study: Bone loss in GC treated rats was confirmed by significantly decreased BMD, bone strength, cancellous bone mass and architecture, osteoblast distribution, bone formation, marrow microvessel density and diameter along with down-regulation of marrow BMPs expression and increased adipogenesis. Daily treatment with Sal B (40 mg/kg/d) for 12 weeks in GC male rats prevented GC-induced cancellous bone loss and increased adipogenesis while increasing cancellous bone formation rate with improved local microcirculation by capillary dilation. Treatment with Sal B at a higher dose (80 mg/kg/d) not only prevented GC-induced osteopenia, but also increased cancellous bone mass and thickness, associated with increase of marrow BMPs expression, inhibited adipogenesis and further increased microvessel diameters. (2) In vitro study: In concentration from 10−6 mol/L to 10−7 mol/L, Sal B stimulated bone marrow stromal cell (MSC) differentiation to osteoblast and increased osteoblast activities, decreased GC associated adipogenic differentiation by down-regulation of PPARγ mRNA expression, increased Runx2 mRNA expression without osteoblast inducement, and, furthermore, Sal B decreased Dickkopf-1 and increased β-catenin mRNA expression with or without adipocyte inducement in MSC. We conclude that Sal B prevented bone loss in GC-treated rats through stimulation of osteogenesis, bone marrow angiogenesis and inhibition of adipogenesis

Integration analysis of long non-coding RNA (lncRNA) role in tumorigenesis of colon adenocarcinoma

Background: Colon adenocarcinoma (COAD) is one of the most common gastrointestinal cancers globally. Molecular aberrations of tumor suppressors and/or oncogenes are the main contributors to tumorigenesis. However, the exact underlying mechanisms of COAD pathogenesis are clearly not known yet. In this regard, there is an urgent need to indicate promising potential diagnostic and prognostic biomarkers in COAD patients. Methods: In the current study, level 3 RNA-Seq and miR-Seq data and corresponding clinical data of colon adenocarcinoma (COAD) were retrieved from the TCGA database. The "limma"package in R software was utilized to indicate the differentially expressed genes. For in silico functional analysis, GO and KEGG signaling pathways were conducted. PPI network was constructed based on the STRING online database by Cytoscape 3.7.2. A ceRNA network was also constructed by "GDCRNATools"package in R software. Kaplan-Meier survival analysis (log-rank test) and ROC curve analysis were used to indicate the diagnostic and prognostic values of the biomarkers. Results: The differential expression data demonstrated that 2995 mRNAs, 205 lncRNAs, and 345 miRNAs were differentially expressed in COAD. The GO and KEGG pathway analysis indicated that the differentially expressed mRNAs were primarily enriched in canonical processes in cancer. The PPI network showed that the CDKN2A, CCND1, MYC, E2F, CDK4, BRCA2, CDC25B, and CDKN1A proteins were the critical hubs. In addition, the Kaplan-Meier analysis revealed that 215 mRNAs, 14 lncRNAs, and 39 miRNAs were associated with overall survival time in the patients. Also, the ceRNA network data demonstrated that three lncRNAs including MIR17HG, H19, SNHG1, KCNQ1OT1, MALAT1, GAS5, SNHG20, OR2A1-AS1, and MAGI2-AS3 genes were involved in the development of COAD. Conclusions: Our data suggested several promising lncRNAs in the diagnosis and prognosis of patients with COAD. © 2020 The Author(s)

SYSTEM DYNAMICS-BASED CONFLICT RESOLUTION MODEL FOR RIVER WATER QUALITY MANAGEMENT

System dynamics approach by simulating a bargaining process can be used for resolving conflict of interests in water quality management. This approach can be a powerful alternative for traditional approaches for conflict resolution, which often rely on classical game theory. Waste load allocation models for river water quality management determine the optimal monthly waste load allocation to each point load. Most of these approaches are based on the multi-objective optimization models and do not consider the existing conflicts. In this study, a system dynamics-based conflict resolution model is presented for monthly waste load allocation in river systems. In this model, the stakeholders and decision-makers negotiate with each other considering their relative authorities, aspirations and dissatisfactions. System dynamics approach is actually used for simulating the bargaining process among the players. The model incorporates the objectives and preferences of stakeholders and decision-makers of the system in the form of utility functions and could provide a final agreement among the players. To evaluate the spatial and temporal variation of the concentration of the water quality indicator in the system, a water quality simulation model is also linked to the conflict resolution model. In the proposed model, a pre-assigned utility is allocated to different water users and the results are evaluated using a simulation model. The allocated utilities are tested and adjusted in order to provide an agreement between the assumed utilities and the utilities assigned by the model. The proposed model is applied to the Karkheh River system located in the southwest of Iran. The results show that the model can effectively incorporate the preferences of the players in providing a final agreement and the runtime of the proposed model is much less than the classical conflict resolution models. It is also shown that the waste load allocation can significantly reduce number and duration of the periods in which the river water quality violates the standards

Acute pulmonary embolism caused by enlarged uterine leiomyoma: A rare presentation

Objective: Management of emergency care. Background: Deep venous thrombosis (DVT) and subsequent pulmonary embolism (PE) caused by pelvic vein compression are rare and life-threatening complications of leiomyoma of the uterus. Case Report: We report a 42-year-old virgin woman with a history of leiomyoma who presented to the emergency department with complaints of dyspnea and pleuritic chest pain with transient spotting. On physical examination, she had a non-tender abdomen with a 20-week size uterus. Imaging investigations revealed an acute DVT in her left leg and a huge uterine-derived mass compressing the common iliac veins. Transesophageal echocardiography (TEE) demonstrated an echogenic mass in her right pulmonary artery consistent with thrombosis. The patient was completely cured using thrombolytic therapy and myomectomy, and was well at 1 year after thrombolysis. Conclusions: PE caused by pelvic vein compression is a rare complication of leiomyoma, which should be considered. Thrombolytic therapy associated with myomectomy can be implemented for treating such cases, and TEE can be used for diagnosing suspected high-risk PE. © Am J Case Rep, 2014

Enhancing spatial resolution of GRACE-derived groundwater storage anomalies in Urmia catchment using machine learning downscaling methods

The Urmia lake in north-west Iran has dried up to perilously low levels in the past two decades. In this study, we investigate the drivers behind the decline in lake water level with the help of in-situ and remote sensing data. We use total water storage (TWS) changes from the gravity recovery and climate experiment (GRACE) satellite mission. TWS from GRACE includes all the water storage compartments in a column and is the only remote sensing product that can help in estimating groundwater storage (GWS) changes. The coarse spatial (approx. 300 km) resolution of GRACE does not allow us to identify local changes that may have led to the Urmia lake disaster. In this study, we tackle the poor resolution of the GRACE data by employing three machine learning (ML) methods including random forest (RF), support vector regression (SVR) and multi-layer perceptron (MLP). The methods predict the groundwater storage anomaly (GWSA), derived from GRACE, as a function of hydro-climatic variables such as precipitation, evapotranspiration, land surface temperature (LST) and normalized difference vegetation index (NDVI) on a finer scale of 0.25° × 0.25°. We found that i) The RF model exhibited highest R (0.98), highest NSE (0.96) and lowest RMSE (18.36 mm) values. ii) The RF downscaled data indicated that the exploitation of groundwater resources in the aquifers is the main driver of groundwater storage and changes in the regional ecosystem, which has been corroborated by few other studies as well. The impact of precipitation and evapotranspiration on the GWSA was found to be rather weak, indicating that the anthropogenic derivers had the most significant impact on the GWSA changes. iii) We generally observed a significant negative trend in GWSA, having also significant positive correlations with the well data. However, over regions with dam construction significant negative correlations were found.</p