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1.
Nature ; 2024 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-38867046

RESUMO

Broken time-reversal symmetry in the absence of spin order indicates the presence of unusual phases such as orbital magnetism and loop currents1-4. The recently discovered kagome superconductors AV3Sb5 (where A is K, Rb or Cs)5,6 display an exotic charge-density-wave (CDW) state and have emerged as a strong candidate for materials hosting a loop current phase. The idea that the CDW breaks time-reversal symmetry7-14 is, however, being intensely debated due to conflicting experimental data15-17. Here we use laser-coupled scanning tunnelling microscopy to study RbV3Sb5. By applying linearly polarized light along high-symmetry directions, we show that the relative intensities of the CDW peaks can be reversibly switched, implying a substantial electro-striction response, indicative of strong nonlinear electron-phonon coupling. A similar CDW intensity switching is observed with perpendicular magnetic fields, which implies an unusual piezo-magnetic response that, in turn, requires time-reversal symmetry breaking. We show that the simplest CDW that satisfies these constraints is an out-of-phase combination of bond charge order and loop currents that we dub a congruent CDW flux phase. Our laser scanning tunnelling microscopy data open the door to the possibility of dynamic optical control of complex quantum phenomenon in correlated materials.

2.
Nature ; 613(7942): 48-52, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36600069

RESUMO

Achieving electrostatic control of quantum phases is at the frontier of condensed matter research. Recent investigations have revealed superconductivity tunable by electrostatic doping in twisted graphene heterostructures and in two-dimensional semimetals such as WTe2 (refs. 1-5). Some of these systems have a polar crystal structure that gives rise to ferroelectricity, in which the interlayer polarization exhibits bistability driven by external electric fields6-8. Here we show that bilayer Td-MoTe2 simultaneously exhibits ferroelectric switching and superconductivity. Notably, a field-driven, first-order superconductor-to-normal transition is observed at its ferroelectric transition. Bilayer Td-MoTe2 also has a maximum in its superconducting transition temperature (Tc) as a function of carrier density and temperature, allowing independent control of the superconducting state as a function of both doping and polarization. We find that the maximum Tc is concomitant with compensated electron and hole carrier densities and vanishes when one of the Fermi pockets disappears with doping. We argue that this unusual polarization-sensitive two-dimensional superconductor is driven by an interband pairing interaction associated with nearly nested electron and hole Fermi pockets.

3.
Nature ; 601(7891): 35-44, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-34987212

RESUMO

Superconductivity is a remarkably widespread phenomenon that is observed in most metals cooled to very low temperatures. The ubiquity of such conventional superconductors, and the wide range of associated critical temperatures, is readily understood in terms of the well-known Bardeen-Cooper-Schrieffer theory. Occasionally, however, unconventional superconductors are found, such as the iron-based materials, which extend and defy this understanding in unexpected ways. In the case of the iron-based superconductors, this includes the different ways in which the presence of multiple atomic orbitals can manifest in unconventional superconductivity, giving rise to a rich landscape of gap structures that share the same dominant pairing mechanism. In addition, these materials have also led to insights into the unusual metallic state governed by the Hund's interaction, the control and mechanisms of electronic nematicity, the impact of magnetic fluctuations and quantum criticality, and the importance of topology in correlated states. Over the fourteen years since their discovery, iron-based superconductors have proven to be a testing ground for the development of novel experimental tools and theoretical approaches, both of which have extensively influenced the wider field of quantum materials.

4.
Proc Natl Acad Sci U S A ; 119(28): e2119942119, 2022 Jul 12.
Artigo em Inglês | MEDLINE | ID: mdl-35787036

RESUMO

We report results of low-temperature heat-capacity, magnetocaloric-effect, and neutron-diffraction measurements of TmVO4, an insulator that undergoes a continuous ferroquadrupolar phase transition associated with local partially filled 4f orbitals of the thulium (Tm[Formula: see text]) ions. The ferroquadrupolar transition, a realization of Ising nematicity, can be tuned to a quantum critical point by using a magnetic field oriented along the c axis of the tetragonal crystal lattice, which acts as an effective transverse field for the Ising-nematic order. In small magnetic fields, the thermal phase transition can be well described by using a semiclassical mean-field treatment of the transverse-field Ising model. However, in higher magnetic fields, closer to the field-tuned quantum phase transition, subtle deviations from this semiclassical behavior are observed, which are consistent with expectations of quantum fluctuations. Although the phase transition is driven by the local 4f degrees of freedom, the crystal lattice still plays a crucial role, both in terms of mediating the interactions between the local quadrupoles and in determining the critical scaling exponents, even though the phase transition itself can be described via mean field. In particular, bilinear coupling of the nematic order parameter to acoustic phonons changes the spatial and temporal fluctuations of the former in a fundamental way, resulting in different critical behavior of the nematic transverse-field Ising model, as compared to the usual case of the magnetic transverse-field Ising model. Our results establish TmVO4 as a model material and electronic nematicity as a paradigmatic example for quantum criticality in insulators.

5.
Proc Natl Acad Sci U S A ; 117(12): 6424-6429, 2020 Mar 24.
Artigo em Inglês | MEDLINE | ID: mdl-32165540

RESUMO

Electronic nematicity, a correlated state that spontaneously breaks rotational symmetry, is observed in several layered quantum materials. In contrast to their liquid-crystal counterparts, the nematic director cannot usually point in an arbitrary direction (XY nematics), but is locked by the crystal to discrete directions (Ising nematics), resulting in strongly anisotropic fluctuations above the transition. Here, we report on the observation of nearly isotropic XY-nematic fluctuations, via elastoresistance measurements, in hole-doped Ba1-x Rb x Fe2As2 iron-based superconductors. While for [Formula: see text], the nematic director points along the in-plane diagonals of the tetragonal lattice, for [Formula: see text], it points along the horizontal and vertical axes. Remarkably, for intermediate doping, the susceptibilities of these two symmetry-irreducible nematic channels display comparable Curie-Weiss behavior, thus revealing a nearly XY-nematic state. This opens a route to assess this elusive electronic quantum liquid-crystalline state.

6.
Phys Rev Lett ; 128(6): 065901, 2022 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-35213205

RESUMO

The elastic collective modes of a moiré superlattice arise not from vibrations of a rigid crystal but from the relative displacement between the constituent layers. Despite their similarity to acoustic phonons, these modes, called phasons, are not protected by any conservation law. Here, we show that disorder in the relative orientation between the layers and thermal fluctuations associated with their sliding motion degrade the propagation of sound in the moiré superlattice. Specifically, the phason modes become overdamped at low energies and acquire a finite gap, which displays a universal dependence on the twist-angle variance. Thus, twist-angle inhomogeneity is manifested not only in the noninteracting electronic structure of moiré systems, but also in their phononlike modes. More broadly, our results have important implications for the electronic properties of twisted moiré systems that are sensitive to the electron-phonon coupling.

7.
Phys Rev Lett ; 129(23): 237001, 2022 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-36563208

RESUMO

We study superconductivity in a three-dimensional zero-density Dirac semimetal in proximity to a ferroelectric quantum critical point. We find that the interplay of criticality, inversion-symmetry breaking, and Dirac dispersion gives rise to a robust superconducting state at the charge-neutrality point, where no Fermi surface is present. Using Eliashberg theory, we show that the ferroelectric quantum critical point is unstable against the formation of a ferroelectric density wave (FDW), whose fluctuations, in turn, lead to a first-order superconducting transition. Surprisingly, long-range superconducting and FDW orders are found to cooperate with each other, in contrast to the more usual scenario of phase competition. Therefore, we suggest that driving charge neutral Dirac materials, e.g., Pb_{x}Sn_{1-x}Te, through a ferroelectric quantum critical point may lead to superconductivity intertwined with FDW order.

8.
J Cardiovasc Pharmacol ; 79(3): 325-334, 2022 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-35099167

RESUMO

ABSTRACT: Sulforaphane (SFN) is a natural exogenous antioxidant from cruciferous vegetables already shown to improve cardiac function in cardiovascular diseases. The aim of this study was to analyze the effect of SFN treatment on the cardiac function in 2 experimental models of heart disease, ischemia/reperfusion (I/R) and myocardial infarction (MI), and whether an improvement of the cardiac function could be associated with a modulation of calcium-handling proteins. The study was divided into 2 main experiments: experiment 1, ex vivo with the I/R model and experiment 2, in vivo with the MI model. In the I/R model, rats were divided into control and SFN (0.5 mg/kg/d intraperitoneally for 3 days) groups, and the hearts were submitted to global ischemia (20 minutes) followed by reperfusion (20 minutes) in a Langendorff apparatus. SFN did not change left ventricle systolic and diastolic pressures but increased the contractility and relaxation indexes after 20 minutes of reperfusion. These functional changes were accompanied by a decreased protein expression of ryanodine receptor (RyR) and increased expression of p-phospholamban/phospholamban ratio, without alteration in the sarco/endoplasmic calcium ATPase expression. In the MI model, rats were randomly divided into Sham, MI (MI induced by left coronary artery ligation), Sham + SFN (5 mg/kg/d intraperitoneally for 25 days), and MI + SFN groups. Although SFN did not affect cardiac function, it led to a decreased RyR protein expression and reactive oxygen species levels in the left ventricular of the MI + SFN group. These data indicate that SFN modulates calcium-handling proteins and, thus, cardiac inotropism/lusitropism especially when administered previously to an ischemic event.


Assuntos
Cálcio , Infarto do Miocárdio , Animais , Cálcio/metabolismo , Isotiocianatos , Modelos Teóricos , Infarto do Miocárdio/metabolismo , Ratos , Reperfusão , Sulfóxidos
9.
Am J Emerg Med ; 51: 1-5, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34637995

RESUMO

BACKGROUND: Many patients with Coronavirus disease-2019 (Covid-19) present with radiological evidence of pneumonia. Because it is difficult to determine co-existence of bacterial pneumonia, many of these patients are initially treated with antibiotics. We compared the rates of bacterial infections and mortality in Covid-19 patients with pulmonary infiltrates versus patients diagnosed with 'pneumonia' the year previously. METHODS: We conducted a medical record review of patients admitted with Covid-19 and a pulmonary infiltrate and compared them with patients diagnosed with pneumonia admitted in the prior year before the pandemic. Data abstracted included baseline demographics, comorbidities, signs and symptoms, laboratory and microbiological results, and imaging findings. Outcomes were bacterial infections and mortality. Patients presenting with and without Covid-19 were compared using univariable and multivariable analyses. RESULTS: There were 1398 and 1001 patients admitted through the emergency department (ED) with and without Covid-19 respectively. Compared with non-Covid-19 patients, those with Covid-19 were younger (61±18 vs. 65±25 years, P < 0.001) and had a lower Charlson Comorbidity Index (0.7 vs. 1.2, P < 0.001). Bacterial infections were present in fewer Covid-19 than non-Covid-19 patients (8% vs. 13%, P < 0.001), and most infections in Covid-19 were nosocomial as opposed to community acquired in non-Covid-19 patients. CXR was more often read as abnormal and with bilateral infiltrates in patients with Covid-19 (82% vs. 70%, P < 0.001 and 81% vs. 48%, P < 0.001, respectively). Mortality was higher in patients with Covid-19 vs. those without (15% vs. 9%, P < 0.001). Multivariable predictors (OR [95%CI]) of mortality were age (1.04 [1.03-1.05]/year), tachypnea (1.55 [1.12-2.14]), hypoxemia (2.98 [2.04-4.34]), and bacterial infection (2.80 [1.95-4.02]). Compared with non-Covid-19 patients with pneumonia, patients with Covid-19 were more likely to die (2.68 [1.97-3.63]). CONCLUSIONS: The rate of bacterial infections is lower in Covid-19 patients with pulmonary infiltrates compared with patients diagnosed with pneumonia prior to the pandemic and most are nosocomial. Mortality was higher in Covid-19 than non-Covid-19 patients even after adjusting for age, tachypnea, hypoxemia, and bacterial infection.


Assuntos
Infecções Bacterianas/epidemiologia , COVID-19/mortalidade , Coinfecção/epidemiologia , Pneumonia/mortalidade , Adulto , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Comorbidade , Infecção Hospitalar/epidemiologia , Feminino , Hospitalização , Humanos , Hipóxia/epidemiologia , Masculino , Pessoa de Meia-Idade , Missouri/epidemiologia , Estudos Retrospectivos , Fatores de Risco , Taquipneia/epidemiologia
10.
Int J Mol Sci ; 23(6)2022 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-35328600

RESUMO

Stroke is one of the leading causes of death and long-term disabilities worldwide, resulting in a debilitating condition occasioned by disturbances in the cerebral vasculature. Primary damage due to metabolic collapse is a quick outcome following stroke, but a multitude of secondary events, including excitotoxicity, inflammatory response, and oxidative stress cause further cell death and functional impairment. In the present work, we investigated whether a primary ischemic damage into the dorsal striatum may cause secondary damage in the circumjacent corpus callosum (CC). Animals were injected with endothelin-1 and perfused at 3, 7, 14, and 30 post-lesion days (PLD). Sections were stained with Cresyl violet for basic histopathology and immunolabeled by antibodies against astrocytes (anti-GFAP), macrophages/microglia (anti-IBA1/anti MHC-II), oligodendrocytes (anti-TAU) and myelin (anti-MBP), and Anti-Nogo. There were conspicuous microgliosis and astrocytosis in the CC, followed by later oligodendrocyte death and myelin impairment. Our results suggest that secondary white matter damage in the CC follows a primary focal striatal ischemia in adult rats.


Assuntos
Acidente Vascular Cerebral , Substância Branca , Animais , Corpo Caloso/patologia , Bainha de Mielina/metabolismo , Oligodendroglia/metabolismo , Ratos , Acidente Vascular Cerebral/metabolismo
11.
Int J Mol Sci ; 23(20)2022 Oct 19.
Artigo em Inglês | MEDLINE | ID: mdl-36293377

RESUMO

Hippocampus is the brain area where aluminum (Al) accumulates in abundance and is widely associated with learning and memory. In the present study, we evaluate behavioral, tissue, and proteomic changes in the hippocampus of Wistar rats caused by exposure to doses that mimic human consumption of aluminum chloride (AlCl3) in urban areas. For this, male Wistar rats were divided into two groups: Control (distilled water) and AlCl3 (8.3 mg/kg/day), both groups were exposed orally for 60 days. After the Al exposure protocol, cognitive functions were assessed by the Water maze test, followed by a collection for analysis of the global proteomic profile of the hippocampus by mass spectrometry. Aside from proteomic analysis, we performed a histological analysis of the hippocampus, to the determination of cell body density by cresyl violet staining in Cornu Ammonis fields (CA) 1 and 3, and hilus regions. Our results indicated that exposure to low doses of aluminum chloride triggered a decreased cognitive performance in learning and memory, being associated with the deregulation of proteins expression, mainly those related to the regulation of the cytoskeleton, cellular metabolism, mitochondrial activity, redox regulation, nervous system regulation, and synaptic signaling, reduced cell body density in CA1, CA3, and hilus.


Assuntos
Alumínio , Proteômica , Humanos , Ratos , Masculino , Animais , Alumínio/toxicidade , Alumínio/metabolismo , Cloreto de Alumínio/toxicidade , Ratos Wistar , Hipocampo/metabolismo , Compostos de Alumínio/toxicidade
12.
Mol Cancer ; 20(1): 72, 2021 04 29.
Artigo em Inglês | MEDLINE | ID: mdl-33926465

RESUMO

Nonsense-mediated decay (NMD) was first described as a quality-control mechanism that targets and rapidly degrades aberrant mRNAs carrying premature termination codons (PTCs). However, it was found that NMD also degrades a significant number of normal transcripts, thus arising as a mechanism of gene expression regulation. Based on these important functions, NMD regulates several biological processes and is involved in the pathophysiology of a plethora of human genetic diseases, including cancer. The present review aims to discuss the paradoxical, pro- and anti-tumorigenic roles of NMD, and how cancer cells have exploited both functions to potentiate the disease. Considering recent genetic and bioinformatic studies, we also provide a comprehensive overview of the present knowledge of the advantages and disadvantages of different NMD modulation-based approaches in cancer therapy, reflecting on the challenges imposed by the complexity of this disease. Furthermore, we discuss significant advances in the recent years providing new perspectives on the implications of aberrant NMD-escaping frameshifted transcripts in personalized immunotherapy design and predictive biomarker optimization. A better understanding of how NMD differentially impacts tumor cells according to their own genetic identity will certainly allow for the application of novel and more effective personalized treatments in the near future.


Assuntos
Suscetibilidade a Doenças , Regulação Neoplásica da Expressão Gênica , Neoplasias/genética , Degradação do RNAm Mediada por Códon sem Sentido , Animais , Biomarcadores , Transformação Celular Neoplásica/genética , Transformação Celular Neoplásica/metabolismo , Terapia Combinada , Gerenciamento Clínico , Progressão da Doença , Humanos , Terapia de Alvo Molecular , Neoplasias/metabolismo , Neoplasias/patologia , Neoplasias/terapia , Fenótipo , RNA Mensageiro/genética , Transdução de Sinais , Estresse Fisiológico , Microambiente Tumoral/genética
13.
Nat Mater ; 19(10): 1062-1067, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32424369

RESUMO

Nematic order is the breaking of rotational symmetry in the presence of translational invariance. While originally defined in the context of liquid crystals, the concept of nematic order has arisen in crystalline matter with discrete rotational symmetry, most prominently in the tetragonal Fe-based superconductors where the parent state is four-fold symmetric. In this case the nematic director takes on only two directions, and the order parameter in such 'Ising-nematic' systems is a simple scalar. Here, using a spatially resolved optical polarimetry technique, we show that a qualitatively distinct nematic state arises in the triangular lattice antiferromagnet Fe1/3NbS2. The crucial difference is that the nematic order on the triangular lattice is a [Formula: see text] or three-state Potts-nematic order parameter. As a consequence, the anisotropy axes of response functions such as the resistivity tensor can be continuously reoriented by external perturbations. This discovery lays the groundwork for devices that exploit analogies with nematic liquid crystals.

14.
Phys Rev Lett ; 127(4): 047001, 2021 Jul 23.
Artigo em Inglês | MEDLINE | ID: mdl-34355931

RESUMO

We show that unconventional nematic superconductors with multicomponent order parameter in lattices with three- and sixfold rotational symmetries support a charge-4e vestigial superconducting phase above T_{c}. The charge-4e state, which is a condensate of four-electron bound states that preserve the rotational symmetry of the lattice, is nearly degenerate with a competing vestigial nematic state, which is nonsuperconducting and breaks the rotational symmetry. This robust result is the consequence of a hidden discrete symmetry in the Ginzburg-Landau theory, which permutes quantities in the gauge sector and in the crystalline sector of the symmetry group. We argue that random strain generally favors the charge-4e state over the nematic phase, as it acts as a random mass to the former but as a random field to the latter. Thus, we propose that two-dimensional inhomogeneous systems displaying nematic superconductivity, such as twisted bilayer graphene, provide a promising platform to realize the elusive charge-4e superconducting phase.

15.
Arterioscler Thromb Vasc Biol ; 40(10): 2548-2556, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32847389

RESUMO

OBJECTIVE: Preterm birth has been associated with changes in arterial structure and function. Association with complications occurring during the neonatal period, including bronchopulmonary dysplasia, on vascular outcomes in adulthood is unknown. Approach and Results: We evaluated a cohort of 86 adults born preterm (below 30 weeks of gestation), compared to 85 adults born term, at a mean age of 23 years. We performed ultrasonographic assessment of the dimensions of the ascending aorta, carotid and brachial arteries, and estimated flow-mediated dilation, carotid-femoral pulse wave velocity, augmentation index corrected for heart rate, and carotid intima-media thickness. All analyses were performed with and without adjustment for potential confounding variables, including height, sex, and body mass index. Ascending aorta diameter in diastole was smaller in the preterm group, but carotid and brachial arteries were similar. Carotid and brachial strain, a marker of arterial distensibility, was smaller in the preterm group, while carotid-femoral pulse wave velocity, was similar between groups, indicating similar aortic stiffness. Carotid intima-media thickness, endothelial function flow-mediated dilation, blood nitrite, and nitrate levels were similar between groups. Individuals with bronchopulmonary dysplasia had lower brachial artery strain suggesting long-term association of this neonatal complication with vascular structure. Diastolic blood pressure was higher in the preterm group and was associated with decreased brachial and carotid distensibility. CONCLUSIONS: Young adults born preterm display alterations in arterial distensibility that are associated with a history of bronchopulmonary dysplasia.


Assuntos
Aorta/fisiopatologia , Artéria Braquial/fisiopatologia , Displasia Broncopulmonar/complicações , Artérias Carótidas/fisiopatologia , Recém-Nascido Prematuro , Doenças Vasculares/etiologia , Rigidez Vascular , Adolescente , Adulto , Fatores Etários , Aorta/diagnóstico por imagem , Pressão Arterial , Artéria Braquial/diagnóstico por imagem , Displasia Broncopulmonar/diagnóstico , Displasia Broncopulmonar/fisiopatologia , Artérias Carótidas/diagnóstico por imagem , Estudos de Casos e Controles , Estudos Transversais , Feminino , Idade Gestacional , Frequência Cardíaca , Humanos , Recém-Nascido , Masculino , Fatores de Risco , Doenças Vasculares/diagnóstico por imagem , Doenças Vasculares/fisiopatologia , Adulto Jovem
16.
Environ Monit Assess ; 193(12): 789, 2021 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-34757510

RESUMO

Rainfall is generally partitioned into throughfall, stemflow, and interception in ecosystems. Stemflow variability can affect the hydrology, ecology, and soil chemistry patterns. However, the influence of canopy structure and rainfall characteristics on stemflow production in sugarcane plantations which are important for renewable energy production remain poorly understood. By using funnels attached to the sugarcane stems, the present study determined the stemflow amount during the period of sugarcane growth and its relationship with plant development. Approximately, 14% of gross rainfall reached the soil as stemflow, and the funneling ratios was 60. In general, it was observed a positive relationship between stemflow rates with both leaf area index and plant height. This was attributed to an increasing number of acute branching angles of the sugarcane leaves as well as high stem tillering and density. However, at the end of growth cycle, stemflow rate was lower than in previous periods which can be attributed to changes in sugarcane canopy such as stems inclination and lodging, reducing the effectiveness of water conveyance along the stem. Our study showed the need to include stemflow to better understand the hydrology of sugarcane plantations.


Assuntos
Chuva , Saccharum , Ecossistema , Monitoramento Ambiental , Solo , Árvores
17.
Thorax ; 75(6): 494-502, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32217779

RESUMO

BACKGROUND: Although erythropoiesis is impaired and anaemia frequent in neonates born preterm, haematopoiesis in adults born preterm has not been previously studied. OBJECTIVE: We, thus, aimed to evaluate haemoglobin and erythropoietin levels in young adults born preterm, to identify neonatal events associated with erythropoiesis in adulthood and to examine the relationships of haemoglobin levels with respiratory function and blood pressure. METHODS: We assessed a cohort of 101 young adults (ages 18-29) born preterm (≤29 weeks of gestation), in comparison to 105 full-term controls. We measured haemoglobin, erythropoietin levels and blood pressure. We also assessed respiratory function using spirometry. RESULTS: Compared with controls, tobacco use and sex-adjusted haemoglobin levels were 5.3 (95% CI 2.9 to 7.7) g/L higher in preterm-born individuals, but erythropoietin levels were similar. Duration of oxygen supplementation in the neonatal period was independently associated with higher haemoglobin levels in the preterm group. In young adults born preterm with bronchopulmonary dysplasia, airflow limitation was associated with higher haemoglobin levels. Both systolic (SBP) and diastolic (DBP) blood pressure were increased in individuals born preterm (p=0.042 and p=0.0008, respectively). Higher haemoglobin levels were associated with higher SBP and DBP, independently of term or preterm status. Mediation analysis suggests that haemoglobin increase contributes to 37% and 32% of the effect of preterm birth on SBP and DBP, respectively. CONCLUSIONS: Haemoglobin levels are higher in young adults born preterm, while erythropoietin levels are similar, especially in case of bronchopulmonary dysplasia and airflow limitation, and haemoglobin increase is associated with elevated blood pressure in this population.


Assuntos
Eritropoese , Hipertensão/fisiopatologia , Oxigenoterapia , Nascimento Prematuro/fisiopatologia , Adolescente , Adulto , Displasia Broncopulmonar/fisiopatologia , Estudos de Casos e Controles , Feminino , Humanos , Recém-Nascido , Recém-Nascido Prematuro , Masculino , Testes de Função Respiratória , Fatores de Risco
18.
Phys Rev Lett ; 125(24): 247001, 2020 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-33412040

RESUMO

High-temperature superconductivity emerges in many different quantum materials, often in regions of the phase diagram where the electronic kinetic energy is comparable to the electron-electron repulsion. Describing such intermediate-coupling regimes has proven challenging as standard perturbative approaches are inapplicable. Here, we employ quantum Monte Carlo methods to solve a multiband Hubbard model that does not suffer from the sign problem and in which only repulsive interband interactions are present. In contrast to previous sign-problem-free studies, we treat magnetic, superconducting, and charge degrees of freedom on an equal footing. We find an antiferromagnetic dome accompanied by a metal-to-insulator crossover line in the intermediate-coupling regime, with a smaller superconducting dome appearing in the metallic region. Across the antiferromagnetic dome, the magnetic fluctuations change from overdamped in the metallic region to propagating in the insulating region. Our findings shed new light on the intertwining between superconductivity, magnetism, and charge correlations in quantum materials.

19.
Ann Emerg Med ; 76(4): 394-404, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32563601

RESUMO

Study objective: Most coronavirus disease 2019 (COVID-19) reports have focused on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) positive patients. However, at initial presentation, most patients' viral status is unknown. Determination of factors that predict initial and subsequent need for ICU and invasive mechanical ventilation is critical for resource planning and allocation. We describe our experience with 4,404 persons under investigation and explore predictors of ICU care and invasive mechanical ventilation at a New York COVID-19 epicenter. Methods: We conducted a retrospective cohort study of all persons under investigation and presenting to a large academic medical center emergency department (ED) in New York State with symptoms suggestive of COVID-19. The association between patient predictor variables and SARS-CoV-2 status, ICU admission, invasive mechanical ventilation, and mortality was explored with univariate and multivariate analyses. Results: Between March 12 and April 14, 2020, we treated 4,404 persons under investigation for COVID-19 infection, of whom 68% were discharged home, 29% were admitted to a regular floor, and 3% to an ICU. One thousand six hundred fifty-one of 3,369 patients tested have had SARS-CoV-2-positive results to date. Of patients with regular floor admissions, 13% were subsequently upgraded to the ICU after a median of 62 hours (interquartile range 28 to 106 hours). Fifty patients required invasive mechanical ventilation in the ED, 4 required out-of-hospital invasive mechanical ventilation, and another 167 subsequently required invasive mechanical ventilation in a median of 60 hours (interquartile range 26 to 99) hours after admission. Testing positive for SARS-CoV-2 and lower oxygen saturations were associated with need for ICU and invasive mechanical ventilation, and with death. High respiratory rates were associated with the need for ICU care. Conclusion: Persons under investigation for COVID-19 infection contribute significantly to the health care burden beyond those ruling in for SARS-CoV-2. For every 100 admitted persons under investigation, 9 will require ICU stay, invasive mechanical ventilation, or both on arrival and another 12 within 2 to 3 days of hospital admission, especially persons under investigation with lower oxygen saturations and positive SARS-CoV-2 swab results. This information should help hospitals manage the pandemic efficiently.


Assuntos
Infecções por Coronavirus/terapia , Cuidados Críticos/estatística & dados numéricos , Serviço Hospitalar de Emergência/estatística & dados numéricos , Pneumonia Viral/terapia , Respiração Artificial/estatística & dados numéricos , Adolescente , Adulto , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Betacoronavirus , COVID-19 , Comorbidade , Infecções por Coronavirus/epidemiologia , Infecções por Coronavirus/mortalidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , New York/epidemiologia , Pandemias , Pneumonia Viral/epidemiologia , Pneumonia Viral/mortalidade , Estudos Retrospectivos , Fatores de Risco , SARS-CoV-2 , Adulto Jovem
20.
Proc Natl Acad Sci U S A ; 114(51): 13430-13434, 2017 12 19.
Artigo em Inglês | MEDLINE | ID: mdl-29208710

RESUMO

The paradigmatic example of a continuous quantum phase transition is the transverse field Ising ferromagnet. In contrast to classical critical systems, whose properties depend only on symmetry and the dimension of space, the nature of a quantum phase transition also depends on the dynamics. In the transverse field Ising model, the order parameter is not conserved, and increasing the transverse field enhances quantum fluctuations until they become strong enough to restore the symmetry of the ground state. Ising pseudospins can represent the order parameter of any system with a twofold degenerate broken-symmetry phase, including electronic nematic order associated with spontaneous point-group symmetry breaking. Here, we show for the representative example of orbital-nematic ordering of a non-Kramers doublet that an orthogonal strain or a perpendicular magnetic field plays the role of the transverse field, thereby providing a practical route for tuning appropriate materials to a quantum critical point. While the transverse fields are conjugate to seemingly unrelated order parameters, their nontrivial commutation relations with the nematic order parameter, which can be represented by a Berry-phase term in an effective field theory, intrinsically intertwine the different order parameters.

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