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Objective: To explore the feasibility of constructing an objective tinnitus subtype model based on peripheral blood differentially expressed genes (DEGs) using a combination of Weighted Gene Co-expression Network Analysis (WGCNA) and Random Forest algorithm (RF). Methods: From October 2019 to June 2020, peripheral blood DEGs were obtained from 37 patients (from the Third Affiliated Hospital of Sun Yat-sen University)with chronic subjective high-frequency tinnitus (21 unbothersome type, 16 bothersome type) and 20 healthy volunteers through high-throughput sequencing. WGCNA was used to construct gene modules with different expression patterns and analyze their relationships with tinnitus characteristics. Subsequently, RF was employed to build subtype models, which were evaluated by the area under the receiver operating characteristic curve (AUC), accuracy, and F1-score. Results: A total of 12 351 intergroup DEGs were divided into 9 gene modules. Among them, MEblue, MEgreen, and MEbrown showed significant negative correlations with the healthy volunteer group, while MEpink showed a significant positive correlation with the tinnitus distress group. The "Tinnitus vs. Normal" and "Compensatory vs. Decompensatory" subtype models, based on MEblue and MEpink respectively, both had AUCs greater than 0.80, accuracies above 90%, and F1-scores above 0.90, indicating good performance. Conclusions: Peripheral blood DEGs are potential biological indicators for objective classification of subjective tinnitus. The combined application of WGCNA and the Random Forest algorithm should be a viable approach to constructing an objective tinnitus subtype model. However, further exploration and refinement are needed to validate the model's generalizability, cross-dataset performance, and algorithm optimization.
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Algoritmos , Acúfeno , Humanos , Acúfeno/genética , Estudios de Factibilidad , Perfilación de la Expresión Génica/métodos , Redes Reguladoras de Genes , Curva ROC , Transcriptoma , Secuenciación de Nucleótidos de Alto Rendimiento/métodosRESUMEN
A new perovskite KOsO_{3} has been stabilized under high-pressure and high-temperature conditions. It is cubic at 500 K (Pm-3m) and undergoes subsequent phase transitions to tetragonal at 320 K (P4/mmm) and rhombohedral (R-3m) at 230 K as shown from refining synchrotron x-ray powder diffraction (SXRD) data. The larger orbital overlap integral and the extended wave function of 5d electrons in the perovskite KOsO_{3} allow to explore physics from the regime where Mott and Hund's rule couplings dominate to the state where the multiple interactions are on equal footing. We demonstrate an exotic magnetic ordering phase found by neutron powder diffraction along with physical properties via a suite of measurements including magnetic and transport properties, differential scanning calorimetry, and specific heat, which provide comprehensive information for a system at the crossover from localized to itinerant electronic behavior.
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There has been a long-standing debate about the mechanism of the unusual superconductivity in alkali-intercalated fullerides. In this Letter, using high-resolution angle-resolved photoemission spectroscopy, we systematically investigate the electronic structures of superconducting K_{3}C_{60} thin films. We observe a dispersive energy band crossing the Fermi level with the occupied bandwidth of about 130 meV. The measured band structure shows prominent quasiparticle kinks and a replica band involving the Jahn-Teller active phonon modes, which reflects strong electron-phonon coupling in the system. The electron-phonon coupling constant is estimated to be about 1.2, which dominates the quasiparticle mass renormalization. Moreover, we observe an isotropic nodeless superconducting gap beyond the mean-field estimation (2Δ/k_{B}T_{c}≈5). Both the large electron-phonon coupling constant and large reduced superconducting gap suggest a strong-coupling superconductivity in K_{3}C_{60}, while the electronic correlation effect is suggested by the observation of a waterfall-like band dispersion and the small bandwidth compared with the effective Coulomb interaction. Our results not only directly visualize the crucial band structure but also provide important insights into the mechanism of the unusual superconductivity of fulleride compounds.
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Álcalis , Electrones , Espectroscopía de FotoelectronesRESUMEN
Angle-resolved photoemission spectroscopy with sub-micrometer spatial resolution (µ-ARPES), has become a powerful tool for studying quantum materials. To achieve sub-micrometer or even nanometer-scale spatial resolution, it is important to focus the incident light beam (usually from synchrotron radiation) using x-ray optics, such as the zone plate or ellipsoidal capillary mirrors. Recently, we developed a laser-based µ-ARPES with spin-resolution (LMS-ARPES). The 177 nm laser beam is achieved by frequency-doubling a 355 nm beam using a KBBF crystal and subsequently focused using an optical lens with a focal length of about 16 mm. By characterizing the focused spot size using different methods and performing spatial-scanning photoemission measurement, we confirm the sub-micron spatial resolution of the system. Compared with the µ-ARPES facilities based on the synchrotron radiation, our LMS-ARPES system is not only more economical and convenient, but also with higher photon flux (>5 × 1013 photons/s), thus enabling the high-resolution and high-statistics measurements. Moreover, the system is equipped with a two-dimensional spin detector based on exchange scattering at a surface-passivated iron film grown on a W(100) substrate. We investigate the spin structure of the prototype topological insulator Bi2Se3 and reveal a high spin-polarization rate, confirming its spin-momentum locking property. This lab-based LMS-ARPES will be a powerful research tool for studying the local fine electronic structures of different condensed matter systems, including topological quantum materials, mesoscopic materials and structures, and phase-separated materials.
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Spintronic phenomena to date have been established in magnets with collinear moments, where the spin injection through the spin Seebeck effect (SSE) is always along the out-of-plane direction. Here, we report the observation of a vector SSE in a noncollinear antiferromagnet (AF) LuFeO_{3}, where temperature gradient along the out-of-plane and also the in-plane directions can both inject a pure spin current and generate a voltage in the heavy metal via the inverse spin Hall effect (ISHE). We show that the thermovoltages are due to the magnetization from canted spins in LuFeO_{3}. Furthermore, in contrast to the challenges of generating, manipulating, and detecting spin current in collinear AFs, the vector SSE in LuFeO_{3} is readily viable in zero magnetic field and can be controlled by a small magnetic field of about 150 Oe at room temperature. The noncollinear AFs expand new realms for exploring spin phenomena and provide a new route to low-field antiferromagnetic spin caloritronics and magnonics.
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Objective: To evaluate the clinical value of high-definition intelligent endoscopy (iSCAN) combined with stroboscopy in identifying vocal cord leukoplakia. Methods: Seventy-nine patients with vocal cord leukoplakia who underwent CO2 laser laryngeal microsurgery and diagnosed by histopathology were recruited between October 2020 to August 2021. The morphological features, microvascular morphology and mucosal waves were observed by stroboscope; SPSS 20.0 software was used for statistical analysis. Results: There were 79 patients with a total of 119 lesions (56 on left and 63 on right).Pathological examination showed that 51 sides of the vocal cords were malignant lesions (severe dysplasia, carcinoma in situ and invasive carcinoma), and 68 sides were benign lesions.Under stroboscopy, 69 sides of mucosal wave were normal or slightly decreased, and 50 sides were severely decreased or disappeared.The decrease degree of mucosal wave was positively correlated with malignant lesions (ρ=0.687, P<0.001).Under iSCAN endoscopy, there was a positive correlation between the morphological changes of microvessels at the lesion site (vertical) and the malignant lesion (ρ=0.687, P<0.001).Univariate analysis showed that lesion size, thickness, uneven color, granular elevation, peripheral erythema and asymmetry were positively correlated with malignant lesions (ρ=0.530, 0.401, 0.538, 0.315, 0.497, 0.281, P<0.05).Logistic regression analysis showed that the risk of pathological malignancy with large lesions was 5.437 times higher than those of small lesions, the vertical vascular changes under iSCAN were 8.711 times higher than that of normal vascular morphology, and the severe reduction or disappearance of mucosal waves was 9.12 times higher than that of normal or mild reduction of mucosal waves. Conclusion: ISCAN can be combined with staphyloscopy to comprehensively observe and evaluate the changes of vocal cord morphology, submucosal microvessels and mucosal wave of vocal cord in patients with vocal cord leukoplosis, thus improving the ability to distinguish benign and malignant lesions.
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Enfermedades de la Laringe , Pliegues Vocales , Endoscopía , Humanos , Enfermedades de la Laringe/diagnóstico , Enfermedades de la Laringe/patología , Leucoplasia/diagnóstico , Leucoplasia/patología , Estroboscopía , Pliegues Vocales/patologíaRESUMEN
The data of 18 patients with allergic bronchopulmonary aspergillosis (ABPA) who received aspergillus fumigatus-specific IgG detection from 2015 to 2021 in Peking University Third Hospital were retrospectively analyzed. Among them, 11 were male and 7 were female, aged 18-79 years. All patients had a history of asthma or symptoms of cough and asthma, and aspergillus fumigatus-specific IgE was positive; 16 patients had total serum IgE>500 U/ml, of which 13 patients had total serum IgE>1 000 U/ml. Among other diagnostic indicators, peripheral blood eosinophils were >0.5×109/L in 16 cases; lung CT showed bronchiectasis in 15 cases; serum aspergillus fumigatus-specific IgG was positive (>120 AU/ml) in 10 cases. There was no significant difference in serum total IgE level, peripheral blood eosinophil count, and bronchiectasis ratio between positive and negative cases of aspergillus fumigatus-specific IgG (all P>0.05). In this study, the positive rate of aspergillus fumigatus-specific IgG in patients with ABPA was more than 50%, which has auxiliary value in the diagnosis of ABPA.
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Aspergilosis Broncopulmonar Alérgica , Asma , Bronquiectasia , Aspergilosis Broncopulmonar Alérgica/diagnóstico , Aspergillus fumigatus , Femenino , Humanos , Inmunoglobulina E , Inmunoglobulina G , Masculino , Estudios RetrospectivosRESUMEN
Objective: The results of syphilis antibody screening in Peking University Third Hospital from 2016 to 2020 were analyzed,to explore the characteristics of sex, age and distribution of patients with positive syphilis antibody. Methods: A retrospective study was conducted to collect the results of syphilis antibody in outpatients and inpatients of Peking University Third Hospital from 2016 to 2020. Syphilis antibodies were screened in 626 528 patients aged 1-98 years, 4 232 were retested positive by TPPA test, including 2 132 males (50.4%) and 2 100 females (49.6%). Chemiluminescence immunoassay (CMIA) was used for syphilis antibody screening, and Treponema pallidum particle agglutination (TPPA) test was used for reexamination. SPSS20.0 data statistical analysis software was used to analyze the detection rate, age, sex, department and clinical diagnosis of patients with positive syphilis antibody by χ² test. Results: Among 626 528 patients who were positive for treponema pallidum antibody screening, 4 232 were retested positive by TPPA test, accounting for 0.68% of the total number of patients tested. The number of syphilis tests increased year by year, however the positive detection rate decreased. The positive detection rate of syphilis antibody in 2020 decreased by 18.9% compared with 2016. The positive rate of syphilis antibody in male patients was higher than that in female patients, accounting for 0.80% and 0.59% of the total number of patients tested respectively. The positive rate of syphilis antibody of different genders increased with age, the total positive rate of 0-20, 21-40, 41-60, 61-80,>80 years old were 0.15%, 0.45%, 0.95%, 1.07% and 1.41%, respectively. While the increase rate of males was higher than that of females. The positive rate of male over 80 years old was 18.13 times of the group of 0-20 years old, and 5.54 times in women. The top 6 departments with positive syphilis antibody detection rate were emergency department, oncology department, respiratory department, geriatrics department, endocrinology department and neurology department, and the positive rates were 1.79% (104/5 810),1.46% (55/3 767),1.20% (74/6 167),1.20% (22/1 833),1.10% (32/2 909),1.09% (94/8 624), respectively. From the analysis of clinical diagnosis, the proportion of positive syphilis antibody in infertile patients (0.64%, 672/104 911) was higher than that in naturally conceived patients (0.10%, 24/23 969). Conclusions: From 2016 to 2020, the positive detection rate of syphilis antibody in Peking University Third Hospital decreased year by year. However, the positive detection rate increased with the age of patients. The positive rate of syphilis antibody in male was higher than that in female. The positive rate of syphilis antibody in pregnant women was lower than that in infertile patients.
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Sífilis , Adolescente , Adulto , Anciano de 80 o más Años , Niño , Preescolar , Femenino , Hospitales , Humanos , Lactante , Recién Nacido , Pacientes Internos , Masculino , Pacientes Ambulatorios , Embarazo , Estudios Retrospectivos , Sífilis/diagnóstico , Sífilis/epidemiología , Treponema pallidum , Adulto JovenRESUMEN
(Quasi-)one-dimensional systems exhibit various fascinating properties such as Luttinger liquid behavior, Peierls transition, novel topological phases, and the accommodation of unique quasiparticles (e.g., spinon, holon, and soliton, etc.). Here we study molybdenum blue bronze A0.3MoO3 (A = K, Rb), a canonical quasi-one-dimensional charge-density-wave material, using laser-based angle-resolved photoemission spectroscopy. Our experiment suggests that the normal phase of A0.3MoO3 is a prototypical Luttinger liquid, from which the charge-density-wave emerges with decreasing temperature. Prominently, we observe strong renormalizations of band dispersions, which are recognized as the spectral function of Holstein polaron derived from band-selective electron-phonon coupling in the system. We argue that the strong electron-phonon coupling plays an important role in electronic properties and the charge-density-wave transition in blue bronzes. Our results not only reconcile the long-standing heavy debates on the electronic properties of blue bronzes but also provide a rare platform to study interesting excitations in Luttinger liquid materials.
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Objective: To analyse the clinical characteristics of mercury-toxic nephrotic syndrome and to find the risk factors. Methods: A total of 126 patients with mercury-toxic admitted to Beijing Chaoyang Hospital from January 2017 to January 2020 were selected as the research objectives. General data such as age, gender, mercury exposure history of all patients and laboratory data such as urine mercury and urine creatinine were collected. The clinical manifestations and pathological types of patients with mercury-toxic nephrotic syndrome were analyzed, and the risk factors of mercury-toxic nephrotic syndrome were found by univariate and multivariate logistic regression analysis. Results: Among the 24 patients with mercury-toxic nephrotic syndrome, 1 was poisoned by respiratory tract, 6 were poisoned by digestive tract, and 17 were poisoned by skin absorption. In addition to the manifestations of kidney injury, some of the patients also showed neurological symptoms such as dizziness, fatigue, hand tremor, and limb pain. The main pathological types were membranous nephropathy (9 cases) and micropathological nephropathy (10 cases) . The results of multivariate logistic regression analysis showed that the digestive tract and skin absorption pathways of mercury were risk factors for mercury-toxic nephrotic syndrome (OR=21.099, 23.840, P<0.05) . Conclusion: The absorption pathway of mercury has an important influence on the pathogenesis of mercury-toxic nephrotic syndrome, especially in patients with mercury poisoning absorbed by the skin and digestive tract, the risk of complicating nephrotic syndrome is higher.
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Intoxicación por Mercurio , Mercurio , Síndrome Nefrótico , Humanos , Riñón , Factores de RiesgoRESUMEN
Asparagus stem blight is a regional disease. In the present study, we compared strains of Phomopsis asparagi from six different provinces to determine their biological characteristics and genetic diversity, differences in the pycnidium and conidium production, pathogenicity, and growth rate. Considerable differences were established in the pycnidium and conidium production among the P. asparagi strains from the six studied provinces. The largest pycnidium and conidium production had the strains from Fujian, followed by those from Hainan. The virulence of P. asparagi strains was significantly different but without a correlation with the geographical source of the strain. FJ2 had the highest virulence, followed by HN2, SD4, and SD5, whereas SD5 had the lowest virulence. The colony diameter and dry weight of the strains of asparagus stem blight fungus from the six provinces were substantially different. The colonies of HN1-5 had the largest diameters, whereas those of XT1-5, LT1-3, FJ1-5, and SX6 had smaller diameters. Four primers with good repeatability and strong specificity were selected from 100 intersimple sequence repeat (ISSR) primers. ISSR-PCR amplification was performed on 36 strains of asparagus stem blight fungus, and a large number of repeatable DNA fingerprints were obtained. Most of the amplified fragments were within 300 to 500 bp. In all, 69 total points, 64 multiple points, and 92.75% polymorphism points were established. The number of ISSR gene sites detected by four primers ranged from 14 to 20, with an average of 16 multiple sites. The copolymerization was divided into three groups: XT1-5, LT1-3, and FJ1-5, which were clustered into the first group; SD1-6, SX1-6, and HB1-6, clustered into the second group; and HN1-5 in the third group. The results of the cluster analysis revealed that the strains of the neighboring provinces had a nearer phylogenetic relationship than that between distant ones. Therefore, the system evolution of P. asparagi is related to the geographical distribution of its strains.
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Ascomicetos , Asparagus , Hongos Mitospóricos , Ascomicetos/genética , Variación Genética , FilogeniaRESUMEN
The increase of urbanization level has led to the rapid increase of impervious surface area (ISA). The aim of this work is to clarify the relationship between the ISA and water quality and lay a foundation for the improvement and protection of the water quality in the basin. Taking the Fuxian Lake Basin in Yunnan Province as an example, based on the Landsat ETM+ remote sensing image and the Gram-Schmidt (GS) image fusion algorithm, the four-terminal model and the linear spectral mixture model (LSMM) were used to extract the impervious surface of the watershed from 2006 to 2015. And statistical methods were used to distinguish its relationship with water quality. The results show that the four-terminal model and the linear spectral mixture model can effectively extract the impervious surface information of the Fuxian Lake Basin. The average root mean square error (RMS) of the image decomposition results from 2006 to 2015 was less than 0.02. In the past 10 years, the ISA has changed significantly in the Fuxian Lake Basin. The ISA showed an overall upward trend from 2006 to 2015. It increased from 24.73 km2 in 2006 to 35.14 km2 in 2015, an increase of 10.81 km2. From the value anomaly, the ISA in 2006 and 2009 is lower than the multiyear average, and those in the other years are higher than the multiyear average. The percentage of ISA in the basin was significantly positively correlated with Chemical Oxygen Demand-Mn (CODMn) and total phosphorus (TP) (r is 0.772, 0.763), and the correlation in the flooding season was greater than that in the dry season. The ISA threshold for water quality deterioration is around 10% in the Fuxian Lake Basin. Reducing ISA coverage, controlling ISA to less than 10%, and preventing nonpoint source pollution during flooding season will be the best measures to effectively improve the water quality environment in the basin.
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Monitoreo del Ambiente , Lagos/química , Contaminación Química del Agua/análisis , Análisis de la Demanda Biológica de Oxígeno , China , Monitoreo del Ambiente/métodos , Fenómenos Geológicos , Modelos Teóricos , Fósforo/análisis , Estaciones del Año , Urbanización , Contaminación Química del Agua/prevención & controlRESUMEN
BACKGROUND AND PURPOSE: MicroRNAs (miRNAs) have been demonstrated to play crucial roles in the early stage of acute ischaemic stroke (AIS). The purpose of this study was to investigate the expression patterns of miRNAs in peripheral blood mononuclear cells (PBMCs) from AIS patients and further explore related molecular mechanisms in stroke-induced immunodeficiency syndrome (SIDS). METHODS: The miRNA expression patterns of PBMCs were detected by miRNA microarray and validated by quantitative real-time polymerase chain reaction (qRT-PCR) in AIS patients and healthy controls. Bioinformatics methods and luciferase reporter assays were used to detect the downstream target genes. Following stimulation with lipopolysaccharide and interleukin-4, the expression of miR-4443, tumor necrosis factor receptor associated factor 4 (TRAF4) and the nuclear factor kappa B (NF-κB) pathway were evaluated. Furthermore, transfection with miR-4443 mimic or inhibitor in the monocytes was carried out to gain insight into the mechanisms in SIDS. RESULTS: Interleukin-10 in AIS patients was significantly higher than that of healthy controls. The miRNA microarray analysis and qRTPCR validation showed that only miR-4443 was upregulated expressed in PBMCs from AIS patients, especially in monocytes. miR-4443 was shown to directly interact with the 3' untranslated regions of TRAF4, resulting in suppression of TRAF4 protein expression. Furthermore, the expression of miR-4443 and TRAF4 was regulated by stimulation with lipopolysaccharide or interleukin-4. Additionally, overexpression of miR-4443 suppressed the TRAF4/Iκα/NF-κB signaling pathway to activate the expression of anti-inflammatory cytokines in monocytes. CONCLUSIONS: The increased expression of miR-4443 induced monocyte dysfunction by targeting TRAF4, which may function as a crucial mediator in SIDS.
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Isquemia Encefálica , Accidente Cerebrovascular , Humanos , Terapia de Inmunosupresión , Leucocitos Mononucleares , MicroARNs , Monocitos , Factor 4 Asociado a Receptor de TNF , Factor de Necrosis Tumoral alfaRESUMEN
ABSTRACT: Objective To discuss the related factors influencing the initiation time of forensic psychiatric assessment by analysis of the initiation time of forensic psychiatric assessment of criminal cases in Hunan Province. Methods Related data in assessment files of criminal cases accepted by 8 forensic psychiatric assessment institutions in Hunan Province from January 1, 2011 to December 31, 2016 were extracted. The Logistic regression analysis was used to explore the factors influencing the initiation time of forensic psychiatric assessment. After using property score matching ï¼PSMï¼ to control the influence of confounding factors, the efficiency of public security organs to initiate assessments of suspects with ï¼withoutï¼ mental disorders and with ï¼withoutï¼ responsibilities were compared. Results A total of 4 346 cases were included. The Logistic regression analysis suggested that the factors independently related to the initiation time of assessment includeï¼ cause of assessment, nationality of the assessed, history of diagnosis and treatment of mental illnesses, history of crimes, history of drug abuse, and status of alcohol consumption before the crime ï¼all P<0.05ï¼. The initiation time of assessment of suspects diagnosed with mental disorder was shorter than those with none ï¼P<0.05ï¼; the initiation time of assessment of suspects without criminal responsibility was shorter than those with responsibility ï¼P<0.05ï¼. After using PSM to control confounding factors, the differences above still existed. Conclusion The cause of assessment, nationality of the assessed, history of diagnosis and treatment of mental illnesses, history of crimes, history of drug abuse, and status of alcohol consumption before the crime are factors that influence the efficiency of public security organs to initiate forensic psychiatric assessments. Under the current assessment initiation mode, forensic psychiatric assessment of suspects who have mental disorders, especially those with no responsibility may be given priority to initiate.
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Criminales , Psiquiatría Forense , Trastornos Mentales/psicología , Crimen , Humanos , Escalas de Valoración PsiquiátricaRESUMEN
The nature of the pseudogap phase of the copper oxides ('cuprates') remains a puzzle. Although there are indications that this phase breaks various symmetries, there is no consensus on its fundamental nature1. Fermi-surface, transport and thermodynamic signatures of the pseudogap phase are reminiscent of a transition into a phase with antiferromagnetic order, but evidence for an associated long-range magnetic order is still lacking2. Here we report measurements of the thermal Hall conductivity (in the x-y plane, κxy) in the normal state of four different cuprates-La1.6-xNd0.4SrxCuO4, La1.8-xEu0.2SrxCuO4, La2-xSrxCuO4 and Bi2Sr2-xLaxCuO6+δ. We show that a large negative κxy signal is a property of the pseudogap phase, appearing at its critical hole doping, p*. It is also a property of the Mott insulator at p ≈ 0, where κxy has the largest reported magnitude of any insulator so far3. Because this negative κxy signal grows as the system becomes increasingly insulating electrically, it cannot be attributed to conventional mobile charge carriers. Nor is it due to magnons, because it exists in the absence of magnetic order. Our observation is reminiscent of the thermal Hall conductivity of insulators with spin-liquid states4-6, pointing to neutral excitations with spin chirality7 in the pseudogap phase of cuprates.
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NG2 cells are oligodendrocyte progenitor cells, and have been shown to receive synaptic input from pyramidal neurons to generate action potentials. Whether any change of these cells occurs after status epilepticus (SE) and subsequent temporal lobe epilepsy remains unknown. In the present study, the expression of NG2 was investigated in the mouse hippocampus after pilocarpine-induced status epilepticus (PISE). We showed that reactive NG2 cells were significantly increased from 1 day to 2 months after PISE. Double immunofluorescence indicated that few NG2 cells differentiated into neurons and astrocytes after PISE, whereas the number of NG2 cells was increased significantly in the stratum lucidum of CA3 area from 1 day onwards after PISE. Our results suggest that the significantly increased reactive NG2 cells from acute to chronic stage after PISE may be involved in epileptogenesis.
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Antígenos/metabolismo , Proliferación Celular/fisiología , Epilepsia/inducido químicamente , Epilepsia/patología , Hipocampo/patología , Células Precursoras de Oligodendrocitos/patología , Proteoglicanos/metabolismo , Animales , Antígeno CD11b/metabolismo , Calbindina 2/metabolismo , Calbindinas/metabolismo , Proliferación Celular/efectos de los fármacos , Proteína Ácida Fibrilar de la Glía/metabolismo , Masculino , Ratones , Agonistas Muscarínicos/toxicidad , Células Precursoras de Oligodendrocitos/efectos de los fármacos , Células Precursoras de Oligodendrocitos/metabolismo , Pilocarpina/toxicidad , Factores de TiempoRESUMEN
The three central phenomena of cuprate (copper oxide) superconductors are linked by a common doping level p*-at which the enigmatic pseudogap phase ends and the resistivity exhibits an anomalous linear dependence on temperature, and around which the superconducting phase forms a dome-shaped area in the phase diagram1. However, the fundamental nature of p* remains unclear, in particular regarding whether it marks a true quantum phase transition. Here we measure the specific heat C of the cuprates Eu-LSCO and Nd-LSCO at low temperature in magnetic fields large enough to suppress superconductivity, over a wide doping range2 that includes p*. As a function of doping, we find that Cel/T is strongly peaked at p* (where Cel is the electronic contribution to C) and exhibits a log(1/T) dependence as temperature T tends to zero. These are the classic thermodynamic signatures of a quantum critical point3-5, as observed in heavy-fermion6 and iron-based7 superconductors at the point where their antiferromagnetic phase comes to an end. We conclude that the pseudogap phase of cuprates ends at a quantum critical point, the associated fluctuations of which are probably involved in d-wave pairing and the anomalous scattering of charge carriers.
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Gap junctions play an important role in the synchronization activity of coupled cells. Hippocampal inhibitory interneurons are involved in epileptogenesis and seizure activity, and express gap junction protein connexin (Cx) 36. Cx36 is also localized in the axons (mossy fibers) of granule cells in the dentate gyrus. While it has been documented that Cx36 is involved in epileptogenesis, there are still controversies regarding the expression levels of Cx36 at different developmental stages of human and animal models of epileptogenesis. In this study, the expression of Cx36 was investigated in the mouse hippocampus at 1â¯h, 4â¯h during pilocarpine-induced status epilepticus (PISE) and 1 week, 2 months after PISE. We found that Cx36 was down-regulated in neurons at different time points during and after PISE, whereas it was increased significantly in the stratum lucidum of CA3 area at 2 months after PISE. Double immunofluorescence indicated that Cx36 was localized in parvalbumin (PV) immunopositive interneuron in CA1 area and in mossy fibers and their terminals in the stratum lucidum of CA3 area. It suggests that decreased expression of Cx36 in interneurons may be related to less effective inhibitory control of excitatory activity of hippocampal principal neurons. However, the increased Cx36 immunopositive product in mossy fibers at the chronic stage after PISE may enhance the contacts between granule cells in the dentate gyrus and pyramidal neurons in CA3 area. The two different changes of Cx36 may be implicated in the epileptogenesis.
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Conexinas/metabolismo , Hipocampo/metabolismo , Agonistas Muscarínicos/toxicidad , Pilocarpina/toxicidad , Estado Epiléptico/inducido químicamente , Estado Epiléptico/patología , Animales , Regulación de la Expresión Génica/efectos de los fármacos , Hipocampo/efectos de los fármacos , Masculino , Ratones , Parvalbúminas/metabolismo , Fosfopiruvato Hidratasa/metabolismo , Factores de Tiempo , Proteína delta-6 de Union ComunicanteRESUMEN
The properties of cuprate high-temperature superconductors are largely shaped by competing phases whose nature is often a mystery. Chiefly among them is the pseudogap phase, which sets in at a doping p* that is material-dependent. What determines p* is currently an open question. Here we show that the pseudogap cannot open on an electron-like Fermi surface, and can only exist below the doping p FS at which the large Fermi surface goes from hole-like to electron-like, so that p* ≤ p FS. We derive this result from high-magnetic-field transport measurements in La1.6-x Nd0.4Sr x CuO4 under pressure, which reveal a large and unexpected shift of p* with pressure, driven by a corresponding shift in p FS. This necessary condition for pseudogap formation, imposed by details of the Fermi surface, is a strong constraint for theories of the pseudogap phase. Our finding that p* can be tuned with a modest pressure opens a new route for experimental studies of the pseudogap.
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The first known magnetic mineral, magnetite, has unusual properties, which have fascinated mankind for centuries; it undergoes the Verwey transition around 120 K with an abrupt change in structure and electrical conductivity. The mechanism of the Verwey transition, however, remains contentious. Here we use resonant inelastic X-ray scattering over a wide temperature range across the Verwey transition to identify and separate out the magnetic excitations derived from nominal Fe2+ and Fe3+ states. Comparison of the experimental results with crystal-field multiplet calculations shows that the spin-orbital dd excitons of the Fe2+ sites arise from a tetragonal Jahn-Teller active polaronic distortion of the Fe2+O6 octahedra. These low-energy excitations, which get weakened for temperatures above 350 K but persist at least up to 550 K, are distinct from optical excitations and are best explained as magnetic polarons.