Reconstruction de la surface de Fermi par ordre de densité de charge dans le supraconducteur cuprate LSCO

Abstract: Since the discovery of cuprate superconductors in 1986, the key enduring question is: why is the superconducting transition temperature Tc so high? An answer to this question requires that we understand the link between the superconducting phase and two other phases of cuprates: a phase of charge-density-wave (CDW) order and themysterious pseudogap phase. We also need to understand the link between the latter two phases. For my MSc project, my goal was to delineate the region of CDWorder in the doping phase diagram of the cuprate La2−xSrxCuO4 (LSCO), in the T = 0 limit in the absence of superconductivity. For this purpose, I performed measurements of the Hall coefficient RH and the Seebeck coefficient S at low temperature and high magnetic field, on several samples of LSCO in the doping range from x = 0.07 to x = 0.15. Because the magnetic field needed to suppress superconductivity at some of these dopings exceeds 20 T, some measurements had to be done at high magnetic field laboratories, namely the Laboratoire National des Champs Magentique Intenses in Grenoble and the National High Magnetic Field Laboratory in Tallahassee. Transport measurements can detect the presence of CDWorder via the impact that it has on the Fermi surface, namely a reconstruction that produces a small electron-like Fermi pocket, detected as a drop in RH(T) and S/T to negative values at low temperature, as previously established for the cuprate YBCO [1, 2, 3]. In LSCO, we observe a similar drop in RH(T) and S/T to negative values at x = 0.11, 0.12 and 0.13, the three dopings where CDW order has been observed by x-ray diffraction [4]. Extending to lower and higher dopings, we find that CDW-induced Fermi-surface reconstruction is confined to 0.085 < p < 0.15. The fact that the CDW phase ends at pCDW = 0.15, distinctly below the end point of the pseudogap phase at p∗ = 0.18, implies that the two phases are distinct. One can therefore treat them separately in their impact on superconductivity. [Symboles non conformes]Résumé : Depuis la découverte des cuprates supraconducteurs en 1986, la plus importante question qui demeure est : pourquoi leur température de transition supraconductrice Tc est-elle si élevée? Obtenir une réponse à cette question requiert que l’on comprenne le lien entre la phase supraconductrice et deux autres phases des cuprates : une phase d’onde de densité de charge (ODC) et la mystérieuse phase pseudogap. Il est aussi important de comprendre le lien entre ces deux dernières phases. Lors de mon projet de maîtrise, mon but était de délimiter la région dans laquelle l’ODC subsiste dans le diagramme de phase du cuprate La2−xSrxCuO4 (LSCO) dans la limite T = 0 en l’absence de la supraconductivité. À cette fin, j’ai effectué des mesures des coefficients de Hall RH et Seebeck S à basse température et à champ magnétique intense sur différents échantillons de LSCO dans un intervalle de dopage entre x = 0.07 et x = 0.15. Puisque le champ magnétique requis pour supprimer la supraconductivité à certains de ces dopages excède 20 T, certaines mesures ont dû être effectuées dans des laboratoires de champs magnétiques intenses, spécifiquement au Laboratoire National des Champs Magnétiques Intenses à Grenoble et au National High Magnetic Field Laboratory à Tallahassee. Les mesures de transport peuvent détecter la présence d’ODC via l’effet que cet ordre a sur la surface de Fermi, notamment une reconstruction qui produit une petite poche d’électrons, détectable par une chute de RH(T) et de S/T vers des valeurs négatives à basse température tel qu’établi dans le cuprate YBCO [1, 2, 3]. Dans LSCO, nous observons un chute similaire de RH(T) et de S/T vers des valeurs négatives a x = 0.11, 0.12 et 0.13, les trois dopages auxquels l’ODC a été observée par diffraction des rayons X [4]. En étendant l’étude à des dopages plus bas et plus élevés, nous trouvons que la reconstruction de la surface de Fermi induite par l’ODC est confinée à 0.085 < p < 0.15. Le fait que l’ODC disparaisse à pCDW = 0.15, bien en dessous du point limite de la phase pseudogap à p∗ = 0.18, implique que ces deux phases sont distinctes. Elles peuvent donc être traitées séparément lorsqu’on étudie leur impact sur la supraconductivité. [Symboles non conformes

Changes in symptoms of general anxiety, depression, obsessive-compulsive, social anxiety and generalized anxiety during the COVID-19 pandemic in college students

Introduction: Despite the negative consequences of the Covid-19 pandemic on mental health, our knowledge of the changes in the severity of symptoms of psychological disorders during the pandemic is insufficient. Aim: The purpose of this study was to investigate the changes in the symptoms of anxiety, depression, obsessive-compulsive disorder, social anxiety, and generalized anxiety in the student population during the covid-19 pandemic. Method: This study is a longitudinal descriptive study in terms of data collection. A sample of 376 people was selected with the convenience sampling method from the Zanjan University of Medical Sciences and Zanjan National University undergraduate students using an online research platform (Porsal). The sample was evaluated in 4 stages at 6-month intervals from April 2020 to September 2021. BDI-II, BAI, GAD-7, OCI-R, and SPIN were used for data collection. The data were analyzed by repeated measure ANOVA using SPSS version 26, and R software. Results: During the Covid-19 pandemic, the intensity of symptoms of anxiety (p=0.008), obsessive-compulsive (p=0.023) and generalized anxiety (p=0.052) had an increasing trend, and with the subsidence of the pandemic conditions, the intensity of these symptoms has also been reduced. However, the intensity of depression was continuously increasing (p=0.001), and the intensity of social anxiety also had slight changes (p=0.964). Conclusion: Covid-19 pandemic has caused a significant increase in the severity of the symptoms of psychological disorders; therefore, it is necessary to investigate the underlying factors of these changes and other psychological consequences of the Covid-19 pandemic by conducting more extensive studies

Bowel Obstruction Caused by Persimmon Phytobezoars: A Case Report

Background: The term phytobezoar refers to a trapped mass in the gastrointestinal tract caused by the agglomeration of indigestible ingested plant materials, including fibers, skins, and seeds. A persimmon phytobezoar is formed after the frequent consumption of persimmons. The clinical manifestations of persimmon phytobezoars are similar to other phytobezoars and depend on the localization and size of the trapped mass.Case Presentation: Here, we presented a 57-year-old male with persimmon phytobezoars, which finally led to small bowel obstruction. The patient was referred to the emergency room with complaints of severe abdominal pain and frequent vomiting.The patient underwent laparotomy surgery that led to the removal of a portion of his ileum.Conclusion: Overindulgence in taking persimmon can lead to formation of phytobezoar and subsequent obstruction of small intestinal. Persimmon phytobezoars are difficult to break up into pieces because of containing tannins, cellulose, hemicellulose, and lignin

Maternal weight gain might predict child’s weight at the 12th and 24th months of age in Damavand city, North-East Tehran

The purpose of this study was to investigate the possible association between pregnancy weight gain and child weight at the 12th and 24th months of age in Damavand city, North-East Tehran, Iran. Materials and Methods: In a cross-sectional study, using existing data collected by the urban health centers, records of 266 women who attended urban health centers for prenatal care and delivered between March 2004 and March 2008 with singleton term pregnancy were analyzed. Data on pre-pregnancy weight and height, total pregnancy weight gain, mother’s age, parity, neonatal birth weight, birth order, mother’s education, working status, breastfeeding practice and child weight at the 12th and 24th months of age were extracted. Pregnant Women were categorized based on their pre-pregnancy body mass index (BMI) as underweight, normal, and overweight and obese. Chi-square and ANOVA tests were employed to analyze data using SPSS software. Mean (±SD) of gestational weight gain was 11.4±3.9 kg. On average, 34% of mothers had inadequate weight gain, while 44 and 22% gained appropriate and excessive weight, respectively, based on the US Institute of Medicine (IoM-1990) guidelines. About 11, 56, 20 and 13% of mothers were defined as underweight, normal, overweight, and obese based on their BMI values. Initial BMI and educational level was associated with pregnancy weight gain. There was a significant difference between mean child weight at the 12th and 24th months of ages in all three categories of pregnancy weight gain, i.e. inadequate (&lt;6.8 Kg), normal (6.8–11.3 Kg), and excessive (&gt;11.3 Kg) (p&lt; 0.01). Gestational weight gain seemed associated with child weight. Educating and assisting pregnant women to meet the weight gain within recommendations range might therefore be an important strategy to prevent child malnutrition, both under- and overweight, in early life.

Investigation the integration of heliostat solar receiver to gas and combined cycles by energy, exergy, and economic point of views

Due to the high amount of natural gas resources in Iran, the gas cycle as one of the main important power production system is used to produce electricity. The gas cycle has some disadvantages such as power consumption of air compressors, which is a major part of gas turbine electrical production and a considerable reduction in electrical power production by increasing the environment temperature due to a reduction in air density and constant volumetric airflow through a gas cycle. To overcome these weaknesses, several methods are applied such as cooling the inlet air of the system by different methods and integration heat recovery steam generator (HRSG) with the gas cycle. In this paper, using a heliostat solar receiver (HSR) in gas and combined cycles are investigated by energy, exergy, and economic analyses in Tehran city. The heliostat solar receiver is used to heat the pressurized exhaust air from the air compressor in gas and combined cycles. The key parameter of the three mentioned analyses was calculated and compared by writing computer code in MATLAB software. Results showed the use of HSR in gas and combined cycles increase the annual average energy efficiency from 28.4% and 48.5% to 44% and 76.5%, respectively. Additionally, for exergy efficiency, these increases are from 29.2% and 49.8% to 45.2% and 78.5%, respectively. However, from an economic point of view, adding the HRSG increases the payback period (PP) and it decreases the net present value (NPV) and internal rate of return (IRR)

The role of magnesium sulfate in the intensive care unit

Magnesium (Mg) has been developed as a drug with various clinical uses. Mg is a key cation in physiological processes, and the homeostasis of this cation is crucial for the normal function of body organs. Magnesium sulfate (MgSO4) is a mineral pharmaceutical preparation of magnesium that is used as a neuroprotective agent. One rationale for the frequent use of MgSO4 in critical care is the high incidence of hypomagnesaemia in intensive care unit (ICU) patients. Correction of hypomagnesaemia along with the neuroprotective properties of MgSO4 has generated a wide application for MgSO4 in ICU

Evaluation of the Role of Hemoperfusion on Mortality and Morbidity in Patients with Severe Coronavirus Disease 2019 (COVID- 19)

Background: Cytokine storm in severe Covid-19 disease is one of the leading causes of death in these patients. Hemoperfusion is a method used to purify the blood from toxins and inflammatory factors. The aim of this study was to evaluate the effect of hemoperfusion on mortality and morbidity in patients with severe Covid - 19 disease. Methods: This was a retrospective study which performed by reviewing the files of 30 patients with severe Covid-19 disease referred to Sina Hospital affiliated to Tehran University of Medical Sciences in 2020. Thirty patients with severe covid-19 disease and positive PCR participated in the study. All patients received routine treatment protocol for covid-19. Hemoperfusion was used for 15 patients in addition to receiving routine care. The remaining 15 patients were included in the control group. Patients in the hemoperfusion group underwent four sessions of hemoperfusion using continuous renal replacement therapy with continuous venovenous hemofiltration. Results: the ICU length of stay in the control and hemoperfusion groups was 3.40 ± 11.40 and 9.65 ± 16.33 days, respectively (P= 0.075). 8 patients died and 7 patients were discharged in the control group, but 11 patients died and 4 patients were discharged in the hemoperfusion group (P= 0.256). The respiratory rate of patients in the control and hemoperfusion groups decreased from 7.43 ± 29.40 to 4.03 ± 24.60 and from 6.11 ± 31.60 to 5.04 ± 24.46, respectively (P < 0.001). The percentage of arterial blood oxygen saturation in the control and hemoperfusion groups increased from 90.86 ± 5.61 to 93.06 30 4.30 and from 92.33 26 3.26 to 92.06 31 5.31, respectively (P= 0.456). Conclusion: Hemoperfusion could not prevent the mortality of patients and finally out of 15 patients, 11 patients died and 4 patients were discharged. Also, no significant difference was observed between the two groups in terms of arterial blood oxygen saturation

Association of fear of COVID-19 and preventive behaviors (PB) against COVID-19 in Iran

Introduction: The world is currently experiencing a pandemic of COVID-19. The pandemic may affect physicaland mental health. Therefore, this study aims to investigate the fear of COVID-19 and study the relationshipbetween fear of COVID-19 and preventive behaviors against COVID-19. Material and methods: We conducted a web-based cross-sectional study to evaluate the fear of COVID-19 andpreventive behaviors against COVID-19 among the volunteer population in Golestan Province, Iran in May 2020 andJune 2020. The online questionnaire included the Fear of COVID-19 Scale (FCV-19S) and the prevention behaviorsagainst COVID-19, which are used to assess the fear and prevention behaviors of the population, respectively.The data were presented by mean and frequency. Multiple linear regression analysis was performed to identifyfactors associated with Fear of COVID-19 at a significant level of 0.05 in Stata 14. Results: A total of 734 of the 900 individuals contacted completed the survey, with a participation rate of 81.5%.The mean age of the participants was 33.97 ± 10.68 years and 375 (51.9%) were females. The mean Fear ofCOVID-19 score in the participants was 19.69 ± 5.96. There was a significant positive correlation between Fearof COVID-19 and preventive behaviors (r = 0.19, p &lt; 0.001). Multiple linear regression analysis showed participantswith a higher perceived threat of COVID-19, women, married participants, health workers and peoplewith underlying diseases had higher levels of fear of COVID-19. Conclusions: The fear of COVID-19 in Iranian society is high, which indicates the need to pay attention tothe mental health in pandemic conditions. Appropriate intervention action can be designed and implementedaccording to the factors that affect fear. In addition, it should be noted that people with less fear are less likelyto observe the COVID-19’s preventative behaviors

Rhabdomyosarcoma: Current Therapy, Challenges, and Future Approaches to Treatment Strategies

Rhabdomyosarcoma is a rare cancer arising in skeletal muscle that typically impacts children and young adults. It is a worldwide challenge in child health as treatment outcomes for metastatic and recurrent disease still pose a major concern for both basic and clinical scientists. The treatment strategies for rhabdomyosarcoma include multi-agent chemotherapies after surgical resection with or without ionization radiotherapy. In this comprehensive review, we first provide a detailed clinical understanding of rhabdomyosarcoma including its classification and subtypes, diagnosis, and treatment strategies. Later, we focus on chemotherapy strategies for this childhood sarcoma and discuss the impact of three mechanisms that are involved in the chemotherapy response including apoptosis, macro-autophagy, and the unfolded protein response. Finally, we discuss in vivo mouse and zebrafish models and in vitro three-dimensional bioengineering models of rhabdomyosarcoma to screen future therapeutic approaches and promote muscle regeneration.S.G. was supported by the URGP (56977) and CHRIM (OG2023-24-05) operating grant

The Effects of Interaction among Audit Firms Ethical Culture, Audit Team Norms and Auditors Personality Type on Auditors' Intention to Report Detected Errors

Lacking intention to report detected errors by independent auditors reduces the quality of their work and leads to audit firm failure. This study investigates the effects of interaction among auditors personality type, audit firm ethical culture and audit team norms on auditors’ intention to report detected errors. To investigate the interaction effects of the variables, the MODPROBE regression is used. The relation between variables and hypotheses is justified by Theory of Planned Behavior. The sample consists of audit firms, certified auditors in audit organization, and audit firms partners. Data are collected using questionnaire. The results indicate that the existing of audit firm ethical culture and audit team norms moderate the relation between auditors personality type and auditors’ intention to report errors. Thus, in audit firms with strong ethical culture and audit team norms, auditors with any personality type have more intention to report detected errors and misstatements