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For practical applications of superconductors, understanding the vortex matter and dynamics is of paramount importance. An important issue in this context is the transition of the vortex glass, which is a true superconducting phase, into a vortex liquid phase having a linear dissipation. By using multi-harmonic susceptibility studies, we have investigated the vortex glass-vortex liquid phase transitions in CaKFe4As4 and BaFe2(As0.68P0.32)2 single crystals. The principle of our method relates the on-set of the third-harmonic susceptibility response with the appearance of a vortex-glass phase in which the dissipation is non-linear. Similar to the high-critical temperature cuprate superconductors, we have shown that even in these iron-based superconductors with significant lower critical temperatures, such phase transition can be treated as a melting in the sense of Lindemann's approach, considering an anisotropic Ginzburg-Landau model. The experimental data are consistent with a temperature-dependent London penetration depth given by a 3D XY fluctuations model. The fitting parameters allowed us to extrapolate the vortex melting lines down to the temperature of liquid hydrogen, and such extrapolation showed that CaKFe4As4 is a very promising superconducting material for high field applications in liquid hydrogen, with a melting field at 20 K of the order of 100 T.
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Supercondutividade , Vitrificação , Humanos , Transição de Fase , Anisotropia , Febre , HidrogênioRESUMO
Background: Prevention of sudden cardiac death (SCD) early after acute myocardial infarction (AMI) is still a challenge, without clear recommendations in spite of the high incidence of life-threatening ventricular arrhythmias, as implantable cardiac defibrillator (ICD) placement is not indicated in the first 40 days after an AMI; this timing is aleatory and it is owed to fact that the two pivotal studies for evaluation of ICDs in primary prevention, MADIT and MADIT II, excluded the patients within three, respectively four weeks after AMI. Methods: We conducted a retrospective, single-center study that included 77 patients with AMI. All patients were monitored by continuous ECG in the first week after the event. Transthoracic echocardiography was performed at discharge and 40 days after the event. Patients with ejection fraction of 35% or less as assessed by 2D echocardiography 40 days after the MI, which received an ICD for the primary prevention of SCD, were included in the study. The subjects were followed for a median of 38 months, by means of device interrogation and echocardiography. Results: We divided our patients into two groups: in the first group, with left ventricular ejection fraction (LVEF) under 30% after MI, all patients remained in the reduced ejection fraction heart failure category, with an increase from an initial mean of 18.93 ± 4.99% to a mean of 22.18 ± 4.53% after a period of 40 days; we obtained a positive and statistically significant correlation (p < 0.001 and r - 0.547), and all patients presented indication of ICD implant 40 day after MI. In the second group with LVEF between 30% and 35% after MI, the mean LVEF increased from an initial mean of 31.73 ± 1.33% to a mean of 32.33 ± 1.49% after a period of 40 days. A statistically significant correlation (p - 0.02 and r - 0.78) was obtained, although 3 patients presented a LVEF over 35% at 40 days post-MI. Most of the ICD therapies (14.54%) appeared in patients with LVEF < 30% and these patients also presented a higher percentage of NSVT at initial ECG monitoring (54% vs. 50%) and NSVT at ICD interrogation (80% vs. 66.7%); statistical significance was not reached - p > 0.05. The majority of the ICD therapies (11.9% from 13.4%) appeared in patients with NSVT at initial ECG monitoring; also, these presented an increased number of NSVT at ICD interrogation (77.6% vs. 6%) when compared to patients without VT detection at the initial ECG monitoring. Still, statistical significance was not reached - p > 0.15. Conclusions: The patients could benefit from ICD implant earlier than stated in the actual guidelines, since there are insufficient data in the literature for the waiting time of 40 days. Correlated with the increased risk of SCD in the first months post myocardial infarction, the present study proves the benefit of early ICD implantation considering that all our patients with a low ejection fraction immediately after infarction remained in the same category and the great majority (96.1%) required the implantation of an ICD after 40 days. Thus, we could avoid exposing our patients at risk of SCD for an unnecessary prolonged period, and choose early ICD implantation.
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Background: The subendocardial viability ratio (SEVR), also known as the Buckberg index, is a parameter of arterial stiffness with indirect prognostic value in assessing long-term cardiovascular risk. Materials and Methods: We conducted a prospective cohort study on 70 patients with uncomplicated hypertension admitted to a county medical reference hospital. We analyzed demographics, laboratory data, arterial stiffness parameters and cardiovascular risk scores (SCORE and Framingham risk scores) and aimed to identify paraclinical parameters associated with increased cardiovascular risk. Results: Of the arterial stiffness parameters, SEVR correlates statistically significantly with age, central and peripheral systolic blood pressure, as well as with heart rate. SEVR seems to have prognostic value among hypertensive patients by increasing the risk of major cardiovascular events assessed by SCORE and Framingham risk scores. SEVR correlates statistically significantly with serum fibrinogen (p = 0.02) and hemoglobin (p = 0.046). Between pulse wave velocity and lipid parameters (p = 0.021 for low-density lipoprotein cholesterol
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Doenças Cardiovasculares , Hipertensão , Rigidez Vascular , Humanos , Doenças Cardiovasculares/complicações , Análise de Onda de Pulso , Estudos Prospectivos , Fatores de Risco , Hipertensão/complicações , Pressão Sanguínea , Fatores de Risco de Doenças Cardíacas , ColesterolRESUMO
Matching into emergency medicine (EM) is getting progressively more competitive. Applicants must therefore prepare for the possibility of not matching and, accordingly, be ready to participate in the Supplemental Offer and Acceptance Program (SOAP). In this article, we elaborate on the SOAP and the options for applicants who fail to match during Match Week. Alternative courses of action include applying for a preliminary year, matching into a categorical residency program, or aiming to secure EM spots outside the Match through the Council of Emergency Medicine Residency Directors, Society for Academic Emergency Medicine, and American Association of Medical Colleges.
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Medicina de Emergência/educação , Seleção de Pessoal , Escolha da Profissão , Humanos , Internato e Residência , Estados UnidosRESUMO
Implantable cardioverter defibrillators (ICDs) are the cornerstone of primary and secondary prevention of sudden cardiac death (SCD) all around the globe. In almost 40 years of technological advances and multiple clinical trials, there has been a continuous increase in the implantation rate. The purpose of this review is to highlight the grey areas related to actual ICD recommendations, focusing specifically on the primary prevention of SCD. We will discuss the still-existing controversies strongly reflected in the differences between the international guidelines regarding ICD indication class in non-ischemic cardiomyopathy, and also address the question of early implantation after myocardial infarction in the absence of clear protocols for patients at high risk of life-threatening arrhythmias. Correlating the insufficient data in the literature for 40-day waiting times with the increased risk of SCD in the first month after myocardial infarction, we review the pros and cons of early ICD implantation.
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We present the multifrequency measurements of the surface resistance of spark-plasma-sintered MgB2 performed through a dielectric loaded resonator operating at 16.5 and 26.7 GHz. By normally applying magnetic fields ≤1.2 T to the sample surface, we drove it in the mixed state. By means of data-rooted analysis, we found that the sample vortex dynamics could be fully described within a single-component approach. Pinning phenomena were present and characterized by a depinning frequency smaller than the measurement ones. The multiband nature of the superconductor emerged in the flux-flow resistivity, whose field dependence could be interpreted well within theoretical models. By exploiting them, the upper critical field was extracted in the low-temperature range, which exhibited a consistent temperature trend with the values obtained at the onset of the resistive transition near Tc, and was well in line with literature data on other polycrystalline samples.
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OBJECTIVES: To analyse: (1) the associations between different mannose-binding lectin 2 (MBL2) genotypes and susceptibility to bronchial asthma (BA) in Romanian children; and (2) the correlations between several patient sociodemographic variables and MBL2 polymorphisms. METHODS: This prospective observational case-control study included paediatric patients with symptomatic BA and healthy controls. Participants were genotyped for two MBL2 single-nucleotide polymorphisms (SNPs): exon 1 codon 54 A/B variant rs1800450, and -550 promoter H/L variant rs11003125 (GenBank accession). Associations between MBL2 genotypes and susceptibility to BA were determined by calculated odds ratios, and Kendall Tau's correlations were used to investigate the associations between sociodemographic variables and SNPs. RESULTS: Among 59 patients with BA and 65 healthy controls, associations between MBL2 polymorphisms and susceptibility to BA were not found to be statistically significant. Statistically significant weak positive correlations were found between age at diagnosis and A/B genotype, and between the smoking status of biologically male and female parents. A statistically significant weak inverse association was found between male parent smoking status and family history of BA. CONCLUSION: These results may help guide future research into paediatric BA in Romania and Eastern Europe. Due to study limitations, the results require validation in future large-scale studies.
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Asma , Lectina de Ligação a Manose , Asma/epidemiologia , Asma/genética , Estudos de Casos e Controles , Criança , Feminino , Predisposição Genética para Doença , Genótipo , Humanos , Masculino , Lectina de Ligação a Manose/genética , Polimorfismo de Nucleotídeo Único/genética , Romênia/epidemiologiaRESUMO
For high-field power applications of high-temperature superconductors, it became obvious in recent years that nano-engineered artificial pinning centers are needed for increasing the critical current and pinning potential. As opposed to the artificial pinning centers obtained by irradiation with various particles, which is a quite expensive approach, we have studied superconducting samples having self-assembled defects, created during the sample fabrication, that act as effective pinning centers. We introduced a simple, straight-forward method of estimating the frequency-dependent critical current density by using frequency-dependent AC susceptibility measurements, in fixed temperatures and DC magnetic fields, from the positions of the maxima in the dependence of the out-of-phase susceptibility on the amplitude of AC excitation magnetic field. The results are compatible with a model that stipulates a logarithmic dependence of the pinning potential on the probing current. A mathematical derivation allowed us to estimate from the experimental data the pinning potentials in various samples, and in various DC magnetic fields. The resulted values indicate large pinning potentials, leading to very small probability of magnetic flux escaping the pinning wells, hence, leading to very high critical currents in high magnetic fields.
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The deposition of a ferromagnetic layer can affect the properties of high-temperature superconductors underneath. We investigated the influence of ferromagnetic CaRuO3 on the properties of YBa2Cu3O7-x (YBCO) superconducting thin films when the layers are either in direct contact or separated by a barrier layer of 5 nm SrTiO3. Detailed measurements of the magnetic moment of the superconductor and ferromagnet as a function of temperature and magnetic field have been performed using SQUID magnetometry. Magnetometry and relaxation measurements show that the modification of the superconducting properties of YBCO strongly depends on the interaction with the ferromagnetic layer on top. The barrier layer has a significant impact on both the supercon-ducting properties of the YBCO film and the ferromagnetic ordering of CaRuO3. The physical properties mentioned above were discussed in correlation with the materials' structure determined by XRD analysis.
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Superconducting materials have contributed significantly to the development of modern materials science and engineering. Specific technological solutions for their synthesis and processing helped in understanding the principles and approaches to the design, fabrication and application of many other materials. In this review, we explore the bidirectional relationship between the general and particular synthesis concepts. The analysis is mostly based on our studies where some unconventional technologies were applied to different superconductors and some other materials. These technologies include spray-frozen freeze-drying, fast pyrolysis, field-assisted sintering (or spark plasma sintering), nanoblasting, processing in high magnetic fields, methods of control of supersaturation and migration during film growth, and mechanical treatments of composite wires. The analysis provides future research directions and some key elements to define the concept of 'beautiful' technology in materials science. It also reconfirms the key position and importance of superconductors in the development of new materials and unconventional synthesis approaches.
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BACKGROUND: The current cardiovascular disease (CVD) primary prevention guidelines prioritize risk stratification by using clinical risk scores. However, subclinical atherosclerosis may rest long term undetected. This study aimed to evaluate multiple subclinical atherosclerosis parameters in relation to several CV risk scores in asymptomatic individuals. METHODS: A cross-sectional, single-center study included 120 asymptomatic CVD subjects. Four CVD risk scores were computed: SCORE, Framingham, QRISK, and PROCAM. Subclinical atherosclerosis has been determined by carotid intima-media thickness (cIMT), pulse wave velocity (PWV), aortic and brachial augmentation indexes (AIXAo, respectively AIXbr), aortic systolic blood pressure (SBPao), and ankle-brachial index (ABI). RESULTS: The mean age was 52.01 ± 10.73 years. For cIMT-SCORE was more sensitive; for PWV-Framingham score was more sensitive; for AIXbr-QRISK and PROCAM were more sensitive while for AIXao-QRISK presented better results. As for SBPao-SCORE presented more sensitive results. However, ABI did not correlate with any CVD risk score. CONCLUSIONS: All four CV risk scores are associated with markers of subclinical atherosclerosis in asymptomatic population, except for ABI, with specific particularities for each CVD risk score. Moreover, we propose specific cut-off values of CV risk scores that may indicate the need for subclinical atherosclerosis assessment.
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Background: Heart failure (HF) is a complex clinical syndrome that represents a great burden on public health systems due to its increased prevalence, disability and mortality rates. There are multiple triggers that can induce or aggravate a preexisting HF, socioeconomic status (SES) emerging as one of the most common modifiable risk factors. Our study aimed to analyze the influence of certain SES indicators on the outcome, clinical aspects and laboratory parameters of patients with HF in North-Eastern Romania, as well as their relationship with other traditional cardiovascular risk factors. Methods: We conducted a prospective, single-center study comprising 120 consecutively enrolled patients admitted for acute HF. The evaluation of individual SES was based upon a standard questionnaire and evidence from official documents. Results: the patients' age ranged between 18 and 94 years; Out of 120 patients, 49 (40.8%) were women and 71 (59.2%) were men, residing in rural 59 (49.2%) or urban 61 (50.8%) areas. 14.2% were university graduates, while 15.8% had only attended primary school. The majority of the patients are or were employed in the service sector (54.5%), followed by industry (29.2%) and agriculture (20%). The mean monthly income was 306.1 ± 177.4 euro, while the mean hospitalization cost was 2471.8 ± 2073.8 euro per patient. The individual income level was positively correlated with urban area of residence, adequate household sanitation facilities and healthcare access, and negatively associated with advanced age and previous hospitalizations due to HF. However, the individual financial situation was also positively correlated with the increased prevalence of certain cardiovascular risk factors, such as arterial hypertension, anemia or obesity, but not with total cholesterol or male gender. Concerning the direct impact of a poor economic status upon prognosis in the setting of acute HF, our results showed no statistically significant differences concerning the in-hospital or at 1-month follow-up mortality rates. Rather than inducing a direct impact on the short-term outcome, these findings concerning SES indicators are meant to enhance the implementation of policies aimed to provide adequate healthcare for people from all social layers, with a primary focus on modifiable cardiovascular risk factors.
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BACKGROUND: Acute heart failure (HF) represents an increasingly common and challenging presentation in the emergency room, also inducing a great socio-economic burden. Extensive research was conducted toward finding an ideal biomarker of acute HF, both in terms of sensitivity and specificity, but today practicians' interest has shifted towards a more realistic multimarker approach. Natriuretic peptides (NPs) currently represent the gold standard for diagnosing HF in routine clinical practice, but novel molecules, such as sST2, emerge as potentially useful biomarkers, providing additional diagnostic and prognostic value. METHODS: We conducted a prospective, single-center study that included 120 patients with acute HF and 53 controls with chronic HF. Of these, 13 patients (eight with acute HF, five from the control group) associated the coronavirus-19 disease (COVID-19). The diagnosis of HF was confirmed by a complete clinical, biological and echocardiographic approach. RESULTS: The serum levels of all studied biomarkers (sST2, NT-proBNP, cardiac troponin) were significantly higher in the group with acute HF. By area under the curve (AUC) analysis, we noticed that NT-proBNP (AUC: 0.976) still had the best diagnostic performance, closely followed by sST2 (AUC: 0.889). However, sST2 was a significantly better predictor of fatal events, showing positive correlations for both in-hospital and at 1-month mortality rates. Moreover, sST2 was also associated with other markers of poor prognosis, such as the use of inotropes or high lactate levels, but not with left ventricle ejection fraction, age, body mass index or mean arterial pressure. sST2 levels were higher in patients with a positive history of COVID-19 as compared with non-COVID-19 patients, but the differences were statistically significant only within the control group. Bivariate regression showed a positive and linear relationship between NT-proBNP and sST2 (r(120) = 0.20, p < 0.002). CONCLUSIONS: we consider that sST2 has certain qualities worth integrating in a future multimarker test kit alongside traditional biomarkers, as it provides similar diagnostic value as NT-proBNP, but is emerging as a more valuable prognostic factor, with a better predictive value of fatal events in patients with acute HF.
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The most frequent prostate diseases depending on age are prostatitis in young men, benign prostate hypertrophy in men over 50 years old, and prostate cancer (PCa) in elderly patients. The purpose of our study is to evaluate the role of inflammation in the progression of prostate diseases. We used clinical and paraclinical techniques for the positive diagnosis [serum prostate-specific antigen (PSA) determination, we performed transrectal ultrasound to asses the prostate volume and prostate biopsy or transurethral resection of the prostate, where it was imposed]. The prostate tissue specimens were analyzed histopathologically and immunohistochemically. Our results show that PCa patients with higher inflammation rates had a higher Gleason score in both the castration-resistant prostate cancer (CRPC) group and the castration-sensitive group. We have noticed that patients with high inflammation grade also had a much higher International Prostate Symptom Score (IPSS). In conclusion, we can say that in our study, inflammation played an important role in the evolution of benign and malignant prostate diseases; its presence has influenced directly the severity of symptoms, and the aggressiveness of the diseases.