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A space-resolved vacuum ultraviolet spectroscopy is employed to measure impurity emission profiles (500-3200 Å) on EAST. This study successfully captures C IV (1548.20 and 1550.77 Å) lines emitted from carbon ions and derives ion temperatures using Doppler broadening and a collision model based on their intensity ratios. Both the emission intensity and ion temperature profiles are determined. However, the calculated results reveal a lower temperature of around 10-20 eV with the collision model, suggesting a potential need for further correction in subsequent calculations. Furthermore, this study explores relative rotation velocities from the Doppler shift, indicating an increase in toroidal rotation velocity with applied neutral beam injection. The measured results exhibit concordance with the charge exchange recombination spectrometer data. Furthermore, during boron powder dropping discharges on EAST, B II (1623.60, 1623.79, 1623.95, 1624.02, 1624.17, and 1624.38 Å) emission lines exhibiting a similar time behavior trend with boron powder injection are identified. Ion temperatures are measured using B II (1362.46 Å) through the Doppler broadening method. These techniques hold significant promise for future impurity analysis at the edge of EAST, providing valuable insights into the behavior of carbon and boron ions.
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A reversible, first-order transition separating two liquid phases of a single-component material is a fascinating yet poorly understood phenomenon. Here, we investigate the liquid-liquid transition (LLT) ability of two tetraalkylphosphonium ionic liquids (ILs), [P666,14]Cl and [P666,14][1,2,4-triazolide], using differential scanning calorimetry and dielectric spectroscopy. The latter technique also allowed us to study the LLT at elevated pressure. We found that cooling below 205 K transforms [P666,14]Cl and [P666,14][Trz] from one liquid state (liquid 1) to another (the self-assembled liquid 2), while the latter facilitates the charge transport decoupled from structural dynamics. In contrast to temperature, pressure was found to play an essential role in the self-organization of a liquid 2 phase, resulting in different time scales of charge transport for rapidly and slowly compressed samples. Furthermore, τσ(PLL) was found to be much shorter than τσ(TLL, P=atm), which constitutes the first example of non-isochronal behavior of charge transport at LLT. In turn, dielectric studies through the liquid-glass transition revealed the non-monotonic behavior of τσ at elevated pressure for [P666,14]Cl, while for [P666,14][Trz] τσ(Pg) was almost constant. These results highlight the diversity of liquid-liquid transition features within the class of phosphonium ionic liquids.
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Objective: To evaluate the correlation between peri-implant probing depth (PPD) and radiographic bone level (rBL) in implants with peri-implantitis. Methods: From January 2019 to December 2022, 24 patients with 30 implants who suffered from peri-implantitis at the Department of Periodontology, Peking University School and Hospital of Stomatology were included in the present research. SPSS 26.0 software was used to simple random sampling select 30 healthy implants from which with electronic examination records in Department of Periodontology, Peking University School and Hospital of Stomatology from January 2007 to June 2023 as the control group. On the premise of retaining the implant prosthesis, PPD (distance between pocket bottom and peri-implant soft tissue margin) was examined using a Williams periodontal probe with a light force (about 0.2 N), and a total of 4 sites were recorded for each implant. Periapical radiography and cone beam CT were applied to measure the rBL (distance between the reference point at the neck of the implant and the apical point of the bone defect) and the width of the bone defect (DW), and the type of the bone defect was recorded. The correlation and consistency between the diagnosis of PPD and rBL were analyzed. Results: PPD was significantly correlated with rBL in a total of 60 implants in 180 sites (r=0.64, P<0.001). The chi-square test showed an 8.15-fold increase in the detection rate of PD≥6 mm at sites with rBL≥1 mm (P<0.001). Multivariate logistic regression analysis showed that rBL was still statistically associated with PPD after adjustment for jaw position and examination position of implants. Take rBL <1 mm as reference, the odds ratios (OR) of 1 mm≤rBL<2 mm, 2 mm≤rBL<3 mm and rBL≥3 mm group with PPD were 6.23 (P=0.014), 2.77 (P=0.183) and 10.87 (P=0.001), respectively. Conclusions: There is a positive correlation between PPD and rBL in implants with peri-implantitis. PPD can be used as a clinical examination index to assist in estimating the level of peri-implant bone under the premise of retaining the prosthesis.
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Peri-Implantite , Humanos , Peri-Implantite/diagnóstico por imagem , Implantes Dentários , Tomografia Computadorizada de Feixe Cônico , Perda do Osso Alveolar/diagnóstico por imagem , Modelos LogísticosRESUMO
Dimethacrylate-based chemistries feature extensively as resin monomers in dental resin-based materials due to their distinguished overall performance. However, challenges endure, encompassing inadequate mechanical attributes, volumetric shrinkage, and estrogenicity. Herein, we first synthesized a novel resin monomer, 9-armed starburst polyurethane acrylate (NPUA), via the grafting-onto approach. Compared to the primary commercial dental monomer 2,2-bis [p-(2'-hydroxy-3'-methacryloxypropoxy) phenyl] propane (Bis-GMA) (with a viscosity of 1,174 ± 3 Pa·s and volumetric shrinkage of 4.7% ± 0.1%), the NPUA monomer achieves the lower viscosity (158 ± 1 Pa·s), volumetric shrinkage (2.5% ± 0.1%), and cytotoxicity (P < 0.05). The NPUA-based resins exhibit the higher flexural strength, flexural modulus, hardness, and hydrophobicity and lower volumetric shrinkage, water absorption, and solubility compared to the Bis-GMA (70 wt%)/TEGDMA (30 wt%) resins. The NPUA-based composites exhibit significantly higher flexural strength, flexural modulus, and hardness and lower volumetric shrinkage (171.4 ± 3.0 MPa, 12.6 ± 0.5 GPa, 2.0 ± 0.2 GPa, and 3.4% ± 0.2%, respectively) compared to the Bis-GMA group (120.3 ± 4.7 MPa, 9.4 ± 0.7 GPa, 1.5 ± 0.1 GPa, and 4.7% ± 0.2%, respectively; P < 0.05). This work presents a viable avenue for augmenting the physicochemical attributes of dental resins.
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Resinas Acrílicas , Teste de Materiais , Metacrilatos , Poliuretanos , Poliuretanos/química , Viscosidade , Metacrilatos/química , Resinas Compostas/química , Resistência à Flexão , Materiais Dentários/química , Bis-Fenol A-Glicidil Metacrilato/química , Polimerização , Ácidos Polimetacrílicos/química , Dureza , Propriedades de SuperfícieRESUMO
SS 433 is a microquasar, a stellar binary system that launches collimated relativistic jets. We observed SS 433 in gamma rays using the High Energy Stereoscopic System (H.E.S.S.) and found an energy-dependent shift in the apparent position of the gamma-ray emission from the parsec-scale jets. These observations trace the energetic electron population and indicate that inverse Compton scattering is the emission mechanism of the gamma rays. Our modeling of the energy-dependent gamma-ray morphology constrains the location of particle acceleration and requires an abrupt deceleration of the jet flow. We infer the presence of shocks on either side of the binary system, at distances of 25 to 30 parsecs, and that self-collimation of the precessing jets forms the shocks, which then efficiently accelerate electrons.
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The S3 level clinical practice guideline for the prevention and treatment of peri-implant diseases, developed by the European Federation of Periodontology, was published in June, 2023 (DOI: 10.1111/jcpe.13823), which culminated in the recommendations for implementation of various different interventions before, during and after implant placement/loading. Aim of the present article is to summarize and interpret the key points of this guideline and help clinicians understand this guideline better, in order to standardize the prevention and treatment of peri-implant diseases.
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Implantes Dentários , Peri-Implantite , Humanos , Peri-Implantite/diagnóstico , Peri-Implantite/prevenção & controle , PeriodontiaRESUMO
Since the publication of the classification criteria for axial spondyloarthritis (axSpA) by Assessment of SpondyloArthritis international Society (ASAS), a new disease concept "non-radiographic axial spondyloarthritis (nr-axSpA)" has emerged. Some domestic experts in China have translated it as "radiologically negative" axSpA, but it can easily lead to misunderstandings literally, as not all patients with nr-axSpA are completely free from radiological abnormalities. This article briefly describes the evolution of the concept of axSpA, proposes to translate the term of nr-axSpA directly rather than "radiologically negative" axSpA, compares the differences and similarities between nr-axSpA and radiologically negative axSpA, delineates the relationship between nr-axSpA and early ankylosing spondylitis, and points out not all the patients who meet the ASAS classification criteria for nr-axSpA are genuine patients with axSpA, because of the relatively low specificity of the ASAS classification criteria. Five common scenarios easily leading to misdiagnosis of nr-axSpA are exampled to remind domestic colleagues.
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Espondiloartrite Axial não Radiográfica , Espondilartrite , Espondilite Anquilosante , Humanos , Espondilartrite/diagnóstico por imagem , Espondilite Anquilosante/diagnóstico por imagem , Radiografia , Índice de Gravidade de DoençaRESUMO
Dental caries is the most common oral disease and the most common cause of resin restorations. In minimally invasive dentistry, the principle behind cavity preparation is to remove external caries-infected dentin (CID) and preserve internal caries-affected dentin (CAD) and sound dentin (SD). The cavity floor is mainly composed of CAD, but the poor bonding performance of CAD has become a widespread concern. This study evaluated the performance of a new collagen-reactive monomer (ITCM) used as a primer to improve the bonding performance of CAD. The experimental specimens were grouped as follows: SD, CAD, and ITCM-pretreated CAD (CAD-ITCM). Dentin slices were obtained for attenuated total reflectance-Fourier transform infrared (ATR-FTIR) analysis. The bonded samples were subjected to microtensile bond strength analysis after 24 h of water storage or aging by thermocycling, and the bonding interface quality was evaluated by nanoleakage assessment, interfacial nanoindentation testing, and in situ zymography. Cytotoxicity experiments with ITCM were performed. ATR-FTIR showed that the isocyanate groups in ITCM can covalently bind and form hydrogen bonds with the collagen in CAD to mediate chemical bonding. ITCM pretreatment significantly improved the bond strength of CAD (P < 0.05), reduced interfacial nanoleakage, improved the sealing of the bonding interface, enhanced the homogeneity of the hybrid layer, and inhibited matrix metalloproteinase activity. In addition, ITCM presented acceptable biocompatibility for dental restorative application. Taken together, this study reported the application of ITCM to induce collagen-based chemical bonding in the CAD bonding system, which fills the gap in strategies to improve the bonding performance of CAD immediately and after aging and has important clinical application prospects.
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Colagem Dentária , Cárie Dentária , Humanos , Resinas Compostas/química , Adesivos Dentinários/química , Suscetibilidade à Cárie Dentária , Cimentos de Resina/química , Dentina , Resistência à Tração , Condicionamento Ácido do Dente , Teste de Materiais , ColágenoRESUMO
Objective: To explore the risk factors of pulmonary hypertension (PH) in premature infants with bronchopulmonary dysplasia (BPD), and to establish a prediction model for early PH. Methods: This was a retrospective cohort study. Data of 777 BPD preterm infants with the gestational age of <32 weeks were collected from 7 collaborative units of the Su Xinyun Neonatal Perinatal Collaboration Network platform in Jiangsu Province from January 2019 to December 2022. The subjects were randomly divided into a training cohort and a validation cohort at a ratio of 8â¶2 by computer, and non-parametric test or χ2 test was used to examine the differences between the two retrospective cohorts. Univariate Logistic regression and multivariate logistic regression analyses were used in the training cohort to screen the risk factors affecting the PH associated with BPD. A nomogram model was constructed based on the severity of BPD and its risk factors,which was internally validated by the Bootstrap method. Finally, the differential, calibration and clinical applicability of the prediction model were evaluated using the training and verification queues. Results: A total of 130 among the 777 preterm infants with BPD had PH, with an incidence of 16.7%, and the gestational age was 28.7 (27.7, 30.0) weeks, including 454 males (58.4%) and 323 females (41.6%). There were 622 preterm infants in the training cohort, including 105 preterm infants in the PH group. A total of 155 patients were enrolled in the verification cohort, including 25 patients in the PH group. Multivariate Logistic regression analysis revealed that low 5 min Apgar score (OR=0.87, 95%CI 0.76-0.99), cesarean section (OR=1.97, 95%CI 1.13-3.43), small for gestational age (OR=9.30, 95%CI 4.30-20.13), hemodynamically significant patent ductus arteriosus (hsPDA) (OR=4.49, 95%CI 2.58-7.80), late-onset sepsis (LOS) (OR=3.52, 95%CI 1.94-6.38), and ventilator-associated pneumonia (VAP) (OR=8.67, 95%CI 3.98-18.91) were all independent risk factors for PH (all P<0.05). The independent risk factors and the severity of BPD were combined to construct a nomogram map model. The area under the receiver operating characteristic (ROC) curve of the nomogram model in the training cohort and the validation cohort were 0.83 (95%CI 0.79-0.88) and 0.87 (95%CI 0.79-0.95), respectively, and the calibration curve was close to the ideal diagonal. Conclusions: Risk of PH with BPD increases in preterm infants with low 5 minute Apgar score, cesarean section, small for gestational age, hamodynamically significant patent ductus arteriosus, late-onset sepsis, and ventilator-associated pneumonia. This nomogram model serves as a useful tool for predicting the risk of PH with BPD in premature infants, which may facilitate individualized early intervention.
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Displasia Broncopulmonar , Permeabilidade do Canal Arterial , Hipertensão Pulmonar , Pneumonia Associada à Ventilação Mecânica , Sepse , Lactente , Masculino , Recém-Nascido , Humanos , Gravidez , Feminino , Displasia Broncopulmonar/epidemiologia , Recém-Nascido Prematuro , Hipertensão Pulmonar/etiologia , Hipertensão Pulmonar/epidemiologia , Estudos Retrospectivos , Nomogramas , Permeabilidade do Canal Arterial/complicações , Permeabilidade do Canal Arterial/epidemiologia , Pneumonia Associada à Ventilação Mecânica/complicações , Cesárea/efeitos adversos , Idade Gestacional , Fatores de RiscoRESUMO
To investigate the feasibility and safety of the Lasso suture hook in transvaginal sacrospinous ligament fixation, a total of 38 patients with vaginal vault prolapse at or above stage â ¡, and aged 46-75(62.7±12.5)years, who underwent transvaginal sacrospinous ligament fixation at the Second Affiliated Hospital of Soochow University from January 2018 to January 2021 were retrospectively analyzed. After complete exposure of the right sacrospinous ligament, the cervical/uterosacral ligament was sutured to the sacrospinous ligament using Lasso hook and polypropylene sutures. The completion rate of the operation, intraoperative complications, operation time, blood loss, and postoperative situations were observed, and the objective cure rate and subjective satisfaction were followed up. Transvaginal sacrospinous ligament fixation was successfully performed in all 38 patients using Lasso suture hooks. There were no bladder or rectum injuries during the operations, and no pelvic hematoma occurred. The operation time was 15-40 (24±9.5) min; the intraoperative bleeding was 20-60 (40±12.5) ml; the visual analogue scale(VAS)score was 3-5 (3.2±1.4) points on the first day of postoperative, and 2-4 (2.2±1.8) points on the third day of postoperative. No numbness or pain in buttocks and lower limbs after the operation. The 3-month follow-up results showed that the objective surgical success rate of the postoperative pelvic organ prolapse quantitation (POP-Q) score was 100% (38/38). The 1-year follow-up results showed that the objective surgical cure rate of postoperative POP-Q score was 92.1% (35/38). The score of Pelvic Floor Distress Inventory-Short Form 20 (PFDI-20)was 42-180(120.4±44.9)before operation and 8-75 (28.0±14.3) after operation(t=15.90, P<0.001); The score of Pelvic Floor Function Impact Questionnaire-Short Form7 (PFIQ-7) was 52-214(112.8±44.5)before operation and 5-29 (14.3±6.0) after operation (t=14.40, P<0.001), and the subjective satisfaction rate is 89.5% (34/38) conducted by Patient Global Impression of Improvement (PGI-I). Transvaginal sacrospinous ligament fixation with Lasso suture hook is simple, safe, and feasible.
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Ligamentos Articulares , Procedimentos Neurocirúrgicos , Feminino , Humanos , Estudos Retrospectivos , Diafragma da Pelve , SuturasRESUMO
Element isotopes are characterized by distinct atomic masses and nuclear spins, which can significantly influence material properties. Notably, however, isotopes in natural materials are homogenously distributed in space. Here, we propose a method to configure material properties by repositioning isotopes in engineered van der Waals (vdW) isotopic heterostructures. We showcase the properties of hexagonal boron nitride (hBN) isotopic heterostructures in engineering confined photon-lattice waves-hyperbolic phonon polaritons. By varying the composition, stacking order, and thicknesses of h10BN and h11BN building blocks, hyperbolic phonon polaritons can be engineered into a variety of energy-momentum dispersions. These confined and tailored polaritons are promising for various nanophotonic and thermal functionalities. Due to the universality and importance of isotopes, our vdW isotope heterostructuring method can be applied to engineer the properties of a broad range of materials.
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BACKGROUND: Writing and drawing orientation is rarely assessed in clinical routine, although it might have a potential value in detecting impaired verticality perception after right hemispheric stroke (RHS). Assessment tools and criteria must be conceived and validated. We therefore explored the clinimetric properties of a set of quantitative writing and drawing orientation criteria, their ranges of normality, and their tilt prevalence in RHS individuals. NEW METHODS: We asked 69 individuals with subacute RHS and 64 matched healthy controls to write three lines and to copy the Gainotti Figure (house and trees). We determined six criteria referring to the orientation of writing and drawing main axes: for writing, the line and margin orientations, and for drawing, the tree, groundline, wall, and roofline orientations. Orientations were measured by using an electronic protractor from specific landmarks positioned by independent evaluators. RESULTS: The set of criteria fulfilling all clinimetric properties (feasibility, measurability, reliability) comprised the line orientation of the writing and the wall and roofline orientations of the drawing. Writing and drawing tilts were frequent after RHS (about 30% by criterion). COMPARISON WITH EXISTING METHODS: So far, graphomotor orientation was mostly tested qualitatively and could not be objectively appreciated in absence of validated tools and criteria, and without ranges of normality. Writing and drawing tilts may now be assessed both in routine clinical practice and research. CONCLUSIONS: Our study paves the way for investigating the clinical determinants of graphomotor tilts, including impaired verticality perception, to better understand their underlying mechanisms.
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Acidente Vascular Cerebral , Humanos , Reprodutibilidade dos Testes , Percepção Espacial , RedaçãoRESUMO
BACKGROUND: Crohn's disease (CD) is frequently associated with malnutrition, inflammation and a deficiency of vitamin D (VD) with the relationships between these symptoms being poorly defined. VD is a modulator of the immune system and is associated with the onset of CD and disease activity. The level of serum VD may have potential in the assessment of CD activity. This study aimed to evaluate the relationships between VD, nutritional status and inflammation, and to identify more accurate VD thresholds. METHODS: The study included 76 outpatients with CD diagnosed between October 2018 and October 2020 and 76 healthy volunteers. Levels of serum 25(OH)D and nutritional indicators, as well as biochemical and disease activity assessments, were conducted. RESULTS: Patients with CD and healthy participants were found to differ significantly in their 25(OH)D levels as well in levels of nutritional and inflammatory indicators. The optimal VD cut-off value was found to be 46.81 nmol/L for CD development and 35.32 nmol/L for disease activity. Levels of 25(OH)D were correlated with both nutritional status and inflammation. CONCLUSIONS: The VD level is likely to be a useful additional tool in the evaluation of CD patients and predicting the disease activity and clinical response. The VD level may relate both to the nutritional status and levels of inflammation in CD patients, and disease progression.
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Doença de Crohn , Deficiência de Vitamina D , Humanos , Vitamina D , Doença de Crohn/complicações , Estado Nutricional , Deficiência de Vitamina D/complicações , Deficiência de Vitamina D/diagnóstico , Vitaminas , Inflamação/diagnósticoRESUMO
Systemic sclerosis (SSc) is an autoimmune rheumatic disease that is characterized by skin fibrosis with multi-organ involvement. In China, the standardized diagnosis and treatment for SSc is still lacking. Based on the diagnosis criteria and guidelines from China and abroad, Chinese Rheumatology Association developed the current standardization of diagnosis and treatment for SSc. The purposes of this guideline are to standardize clinical management for SSc in China, to interpret the key evaluation tools for SSc, and to recommend therapeutic principle and strategies.
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Reumatologia , Escleroderma Sistêmico , Povo Asiático , China , Fibrose , Humanos , Escleroderma Sistêmico/diagnóstico , Escleroderma Sistêmico/terapiaRESUMO
To investigate the effect and clinical value of morcellation within disposable extraction bag with traction wire through posterior vaginal fornix in laparoscopic myomectomy. A total of 42 patients who underwent laparoscopic myomectomy and morcellation through posterior vaginal fornix in the Second Affiliated Hospital of Soochow University from June 2019 to June 2021 were retrospectively analyzed. After the uterine fibroids were removed, the fibroids were placed into the extraction bag, tightening the mouth of the bag with a traction wire to make it airtight. After the uterine incisions were sutured, the extraction bag was taken out through the posterior fornix of the vagina, and the fibroids were broken up with a scalpel in the bag and taken out. The fibroids were successfully removed from the 42 patients through the posterior fornix of the vagina. There were no fibroids fragments found in the peritoneal cavity and vagina. There were no malignant cells or spindle cells found in the peritoneal lavage cytology before and after the operation. After filling the extraction bags with water, there was no leakage. There were 39 cases of uterine leiomyoma, 2 cases of cell-rich uterine leiomyoma, and 1 case of smooth muscle tumor of uncertain malignant potential in postoperative pathological diagnosis. Forty-two cases were followed up for 6 to 30 months. The posterior vaginal fornix incision healed well and there was no recurrence or metastasis. Morcellation within disposable extraction bag with traction wire through posterior vaginal fornix in laparoscopic myomectomy is a safe and feasible method for fibroids removal, which may help to reduce the dissemination of iatrogenic tumors.
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Laparoscopia , Leiomioma , Morcelação , Miomectomia Uterina , Neoplasias Uterinas , Feminino , Humanos , Laparoscopia/métodos , Leiomioma/cirurgia , Morcelação/métodos , Estudos Retrospectivos , Tração , Miomectomia Uterina/métodos , Neoplasias Uterinas/patologiaRESUMO
Objective: To analyze the effect and main gaps of each stage in the AIDS prevention cascade for men who have sex with men (MSM) provided in intervention projects supported by the China AIDS Fund for non-governmental organizations (CAFNGO) and provide suggestions to improve the quality of cascade services and project management. Methods: Data were collected through the CAFNGO management information system and field interviews to analyze the differences in the number of MSM receiving HIV testing and confirming tests, the newly reported patients, and the number of antiviral treatment (ART) referrals of newly established reported patients among different social organization service areas. A service chain chart was also drawn. Results: Between 2016 and 2020, 1 508 MSM intervention projects were funded by CAFNGO, including 1 183 234 MSM being mobilized to receive HIV testing. However, only 68.8% (1 183 234/1 719 139) of the testing capacity of social organizations was covered by these projects. As a result, 55 783 HIV-positive MSM were detected in preliminary screening, and only 86.6% (48 327/55 783) received confirming tests. The proportion of newly reported infections was 3.8% (45 347/1 183 234). The ratio of antiviral treatment (ART) referrals for newly reported patients between 2017 and 2020 was 89.8% (32 719/36 444). 75.8%(1 143/1 508) of total MSM intervention projects were implemented by community-based organizations (Non-registered civil affairs departments). In comparison, organizations registered in civil affairs departments took up 24.2% (365/1 508) of the total MSM intervention projects. No significant difference was noticed in the proportion of newly reported infected (3.8% and 3.8%) and the ratio of ART referrals (89.7% and 89.9%) between community-based organizations and registered organizations' projects. But these two proportions are significantly different between these two types of organizations in some areas in China. Conclusions: The AIDS prevention cascade established in CAFNGO has effectively promoted the early detection and treatment of infected MSM. However, CAFNGO needs more financial support to extend testing coverage for MSM. Meanwhile, confirmation testing for positives in preliminary screening and ART referrals needs to be improved for newly reported patients. In addition, various capacity building needs to be provided for different social organizations.
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Síndrome da Imunodeficiência Adquirida , Infecções por HIV , Minorias Sexuais e de Gênero , Síndrome da Imunodeficiência Adquirida/prevenção & controle , Antivirais , China/epidemiologia , Infecções por HIV/diagnóstico , Infecções por HIV/prevenção & controle , Homossexualidade Masculina , Humanos , MasculinoRESUMO
The dispersive sweep of fast radio bursts (FRBs) has been used to probe the ionized baryon content of the intergalactic medium1, which is assumed to dominate the total extragalactic dispersion. Although the host-galaxy contributions to the dispersion measure appear to be small for most FRBs2, in at least one case there is evidence for an extreme magneto-ionic local environment3,4 and a compact persistent radio source5. Here we report the detection and localization of the repeating FRB 20190520B, which is co-located with a compact, persistent radio source and associated with a dwarf host galaxy of high specific-star-formation rate at a redshift of 0.241 ± 0.001. The estimated host-galaxy dispersion measure of approximately [Formula: see text] parsecs per cubic centimetre, which is nearly an order of magnitude higher than the average of FRB host galaxies2,6, far exceeds the dispersion-measure contribution of the intergalactic medium. Caution is thus warranted in inferring redshifts for FRBs without accurate host-galaxy identifications.