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1.
J Hosp Med ; 18(10): 888-895, 2023 10.
Artículo en Inglés | MEDLINE | ID: mdl-37584618

RESUMEN

BACKGROUND: Effective team communication during interdisciplinary rounds (IDRs) is a hallmark of safe, efficient, patient-centered care. However, there is limited understanding of optimal IDR structures and procedures. OBJECTIVE: This study aimed to analyze direct observations of physician and nurse interactions during bedside IDR to identify behaviors associated with increased interprofessional communication. DESIGNS, SETTINGS AND PARTICIPANTS: Trained observers audited general medicine ward rounds at an academic medical center using a standardized tool to record physician and nurse behavior and communication in 1007 patient encounters in October 2019 to March 2020. RESULTS: There were significant differences in physician and nurse interaction time among physicians with different levels of training, with attendings demonstrating higher interaction time than residents (5.4 ± 4.6 vs. 4.3 ± 3.7 min, p = .02) and interns or medical students (3.0 ± 3.2 min, p = .002). Attendings were more likely to initiate a conversation about nurse concerns (76.9%) compared to residents (67.9%) and interns or medical students (59.3%, p = .03). Early nurse participation in bedside visits was associated with increased physician and nurse interaction time (5.0 ± 4.6 vs. 1.9 ± 1.7 min, p < .001) and physician initiative to ask about nurse concerns (74.8% vs. 64.3%, p = .04). In addition, physician initiative to ask the nurse for concerns rather than waiting for the nurse to offer concerns without being prompted was associated with a subsequent conversation about those concerns (74.5% vs. 61.8%, p < .001) and the physician asking about patient or family concerns (94.2% vs. 88.4%, p = .01). CONCLUSIONS: Implementing IDR structures and procedures that promote attending physician involvement, physician initiative, and early nurse participation could optimize interdisciplinary communication and quality of care.


Asunto(s)
Médicos , Rondas de Enseñanza , Humanos , Comunicación , Pacientes , Centros Médicos Académicos , Grupo de Atención al Paciente
2.
Placenta ; 140: 90-99, 2023 09 07.
Artículo en Inglés | MEDLINE | ID: mdl-37549442

RESUMEN

INTRODUCTION: To characterize early-gestation changes in placental structure, perfusion, and oxygenation in the context of ischemic placental disease (IPD) as a composite outcome and in individual sub-groups. METHODS: In a single-center prospective cohort study, 199 women were recruited from antenatal clinics between February 2017 and February 2019. Maternal magnetic resonance imaging (MRI) studies of the placenta were temporally conducted at two timepoints: 14-16 weeks gestational age (GA) and 19-24 weeks GA. The pregnancy was monitored via four additional study visits, including at delivery. Placental volume, perfusion, and oxygenation were assessed at both MRI timepoints. The primary outcome was defined as pregnancy complicated by IPD, with group assignment confirmed after delivery. RESULTS: In early gestation, mothers with IPD who subsequently developed fetal growth restriction (FGR) and/or delivered small-for gestational age (SGA) infants showed significantly decreased MRI indices of placental volume, perfusion, and oxygenation compared to controls. The prediction of FGR or SGA by multiple logistic regression using placental volume, perfusion, and oxygenation revealed receiver operator characteristic curves with areas under the curve of 0.81 (Positive predictive value (PPV) = 0.84, negative predictive value (NPV) = 0.75) at 14-16 weeks GA and 0.66 (PPV = 0.78, NPV = 0.60) at 19-24 weeks GA. DISCUSSION: MRI indices showing decreased placental volume, perfusion and oxygenation in early pregnancy were associated with subsequent onset of IPD, with the greatest deviation evident in subjects with FGR and/or SGA. These early-gestation MRI changes may be predictive of the subsequent development of FGR and/or SGA.


Asunto(s)
Enfermedades Placentarias , Placenta , Recién Nacido , Embarazo , Femenino , Humanos , Lactante , Placenta/diagnóstico por imagen , Estudios Prospectivos , Recién Nacido Pequeño para la Edad Gestacional , Retardo del Crecimiento Fetal/diagnóstico por imagen , Retardo del Crecimiento Fetal/etiología , Enfermedades Placentarias/diagnóstico por imagen
3.
J Clin Endocrinol Metab ; 108(2): 281-294, 2023 01 17.
Artículo en Inglés | MEDLINE | ID: mdl-36251771

RESUMEN

CONTEXT: Gestational diabetes (GDM) imposes long-term adverse health effects on the mother and fetus. The role of magnetic resonance imaging (MRI) during early gestation in GDM has not been well-studied. OBJECTIVE: To investigate the role of quantitative MRI measurements of placental volume and perfusion, with distribution of maternal adiposity, during early gestation in GDM. METHODS: At UCLA outpatient antenatal obstetrics clinics, ∼200 pregnant women recruited in the first trimester were followed temporally through pregnancy until parturition. Two placental MRI scans were prospectively performed at 14 to 16 weeks and 19 to 24 weeks gestational age (GA). Placental volume and blood flow (PBF) were calculated from placental regions of interest; maternal adiposity distribution was assessed by subcutaneous fat area ratio (SFAR) and visceral fat area ratio (VFAR). Statistical comparisons were performed using the two-tailed t test. Predictive logistic regression modeling was evaluated by area under the curve (AUC). RESULTS: Of a total 186 subjects, 21 subjects (11.3%) developed GDM. VFAR was higher in GDM vs the control group, at both time points (P < 0.001 each). Placental volume was greater in GDM vs the control group at 19 to 24 weeks GA (P = 0.01). Combining VFAR, placental volume and perfusion, improved the AUC to 0.83 at 14 to 16 weeks (positive predictive value [PPV] = 0.77, negative predictive value [NPV] = 0.83), and 0.81 at 19 to 24 weeks GA (PPV = 0.73, NPV = 0.86). CONCLUSION: A combination of MRI-based placental volume, perfusion, and visceral adiposity during early pregnancy demonstrates significant changes in GDM and provides a proof of concept for predicting the subsequent development of GDM.


Asunto(s)
Diabetes Gestacional , Embarazo , Femenino , Humanos , Placenta/patología , Primer Trimestre del Embarazo , Imagen por Resonancia Magnética , Parto
4.
Cancer Causes Control ; 33(6): 813-821, 2022 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-35312891

RESUMEN

PURPOSE: Current cervical cancer screening guidelines recommend 3-year screening intervals, in contrast to the previous recommendation of annual screening, to prevent over screening and overtreatment. We evaluated the impact of viewing a tablet-based educational tool prior to seeing a clinician on young women's knowledge and understanding of cervical cancer screening, HPV vaccination follow-up of abnormal pap smears, and comfort in communicating with their providers. METHODS: This cross-sectional study was part of a cluster-randomized study of fourteen primary care clinics from January 2015 to December 2016. We developed the cervical cancer education tool in English and Spanish using a community-based approach that included formative work and cognitive interviewing. Clinics were randomized to use the intervention (tablet-based patient education tool) or to participate as a control group. We administered surveys to a convenience sample of 229 English- or Spanish-speaking women aged 19 to 35 years in these clinics. We used descriptive analyses and logistic regression models with cluster-robust standard errors to compare differences among the two groups. RESULTS: Compared to women seen in control clinics, women seen in intervention clinics demonstrated greater knowledge regarding human papilloma virus (HPV (p = 0.004) and understanding (p < 0.001) of cervical cancer screening. Comfort in communicating with providers was not statistically different (p = 0.053). Women in the intervention group felt that the tool helped them understand that an abnormal Pap smear does not require immediate treatment (61.5%). CONCLUSION: Innovative online patient education that is offered prior to patients' interaction with their clinicians can improve their knowledge about cervical cancer prevention and treatment.


Asunto(s)
Infecciones por Papillomavirus , Neoplasias del Cuello Uterino , Estudios Transversales , Detección Precoz del Cáncer , Femenino , Conocimientos, Actitudes y Práctica en Salud , Humanos , Tamizaje Masivo , Prueba de Papanicolaou , Papillomaviridae , Infecciones por Papillomavirus/diagnóstico , Infecciones por Papillomavirus/prevención & control , Encuestas y Cuestionarios , Neoplasias del Cuello Uterino/diagnóstico , Neoplasias del Cuello Uterino/prevención & control , Frotis Vaginal
5.
J Patient Exp ; 9: 23743735221079140, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35187225

RESUMEN

Our objective was to assess the utility of an assessment battery capturing health literacy (HL) and biopsychosocial determinants of health in predicting 30-day readmission in comparison to a currently well-adopted readmission risk calculator. We also sought to capture the distribution of inpatient HL, with emphasis on inadequate and marginal HL (an intermediate HL level). A prospective observational study was conducted to obtain HL and biopsychosocial data on general medicine inpatients admitted to the UCLA health system. Five hundred thirty-seven subjects were tracked prospectively for 30-day readmission after index hospitalization. HL was significantly better at predicting readmission compared to LACE + (Length, admission acuity, comorbidities, emergency room visits) alone (P = .013). A multivariate model including education, insurance, and language comfort was a strong predictor of adequate HL (P < .001). In conclusion, HL offered significant improvement in risk stratification in comparison to LACE + alone. Patients with marginal HL were high-risk, albeit difficult to characterize. Incorporating robust HL and biopsychosocial determinant assessments may allow hospital systems to allocate educational resources towards at-risk patients, thereby mitigating readmission risk.

6.
BMJ Open ; 11(11): e049568, 2021 11 03.
Artículo en Inglés | MEDLINE | ID: mdl-34732478

RESUMEN

INTRODUCTION: Robust randomised trial data have shown that routine preoperative (pre-op) testing for cataract surgery patients is inappropriate. While guidelines have discouraged testing since 2002, cataract pre-op testing rates have remained unchanged since the 1990s. Given the challenges of reducing low-value care despite strong consensus around the evidence, innovative approaches are needed to promote high-value care. This trial evaluates the impact of an interdisciplinary electronic health record (EHR) intervention that is informed by behavioural economic theory. METHODS AND ANALYSIS: This pragmatic randomised trial is being conducted at UCLA Health between June 2021 and June 2022 with a 12-month follow-up period. We are randomising all UCLA Health physicians who perform pre-op visits during the study period to one of the three nudge arms or usual care. These three nudge alerts address (1) patient harm, (2) increased out-of-pocket costs for patients and (3) psychological harm to the patients related to pre-op testing. The nudges are triggered when a physician starts to order a pre-op test. We hypothesise that receipt of a nudge will be associated with reduced pre-op testing. The primary outcome will be the change in the percentage of patients undergoing pre-op testing at 12 months. Secondary outcomes will include the percentage of patients undergoing specific categories of pre-op tests (labs, EKGs, chest X-rays (CXRs)), the efficacy of each nudge, same-day surgery cancellations and cost savings. ETHICS AND DISSEMINATION: The study protocol was approved by the institutional review board of the University of California, Los Angeles as well as a nominated Data Safety Monitoring Board. If successful, we will have created a tool that can be disseminated rapidly to EHR vendors across the nation to reduce inappropriate testing for the most common low-risk surgical procedures in the country. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov identifier: NCT04104256.


Asunto(s)
Extracción de Catarata , Catarata , Economía del Comportamiento , Registros Electrónicos de Salud , Humanos , Atención de Bajo Valor , Ensayos Clínicos Controlados Aleatorios como Asunto
7.
J Nucl Med ; 61(8): 1153-1160, 2020 08.
Artículo en Inglés | MEDLINE | ID: mdl-31924715

RESUMEN

The impact of prostate-specific membrane antigen (PSMA) PET/CT on management of prostate cancer (PCa) patients with biochemical recurrence (BCR) is well established. However, whether and how PSMA PET/CT affects the management of patients undergoing scans for other clinical indications remains unknown. The goal of this study was to determine the impact of 68Ga-PSMA-11 PET/CT on initial and subsequent management decisions in a cohort of PCa patients referred for various indications (i.e., a basket trial) excluding the 2 main classic indications: BCR and presurgical staging. Methods: This was a prospective study of 197 patients that aimed to determine the impact of 68Ga-PSMA-11 PET/CT on PCa stage and management. The indications for PSMA PET/CT were initial staging of nonsurgical candidates (30 patients) and restaging after definitive treatment (167 patients). The restaging cohort comprised patients restaged with known advanced metastatic disease (n = 103), after androgen deprivation therapy only (n = 16), after surgery and with serum prostate-specific antigen levels lower than 0.2 ng/mL (n = 13), after radiation therapy and not meeting the Phoenix criteria (n = 22), and after other primary local treatments (i.e., high-intensity focused ultrasound, focal laser ablation, cryoablation, hyperthermia, or irreversible electroporation) (n = 13). Patients with BCR and candidates for curative surgery were excluded. Impact on management was assessed using pre- and post-PET questionnaires completed by referring physicians, electronic chart review, or patient telephone calls. Results: PSMA PET/CT changed the disease stage in 135 of 197 (69%) patients (upstaging in 38%, downstaging in 30%, and no change in stage in 32%). Management was affected in 104 of 182 (57%) patients. Specifically, PSMA PET/CT impacted the management of patients who were restaged after radiation therapy without meeting the Phoenix criteria for BCR, after other definitive local treatments, and with advanced metastatic disease in 13 of 18 (72%), 8 of 12 (67%), and 59 of 96 (61%), respectively. Conclusion: PSMA PET/CT has a profound impact on stage and management of PCa patients outside the 2 main classic indications (BCR and presurgical staging) across all examined clinical scenarios.


Asunto(s)
Ácido Edético/análogos & derivados , Oligopéptidos , Tomografía Computarizada por Tomografía de Emisión de Positrones , Neoplasias de la Próstata/diagnóstico por imagen , Neoplasias de la Próstata/patología , Anciano , Isótopos de Galio , Radioisótopos de Galio , Humanos , Masculino , Persona de Mediana Edad , Estadificación de Neoplasias , Estudios Prospectivos
8.
Artículo en Inglés | MEDLINE | ID: mdl-28256028

RESUMEN

BACKGROUND: Development of pharyngo-esophageal protective reflexes among infants with hypoxic ischemic encephalopathy (HIE) is unclear. Our aim was to distinguish these reflexes from controls and examine the maturational changes in HIE infants. METHODS: We evaluated 14 HIE infants (seven males) at 41.4±0.6 (HIE Time-1) and 46.5±0.6 (HIE Time-2) weeks postmenstrual age (PMA). Seven controls (three males) were evaluated at 43.5±1.3 weeks PMA. Graded pharyngeal stimulation with liquids (0.1, 0.3, 0.5 mL in triplicate) concurrent with high-resolution manometry was used to analyze sensory-motor components of pharyngeal reflexive swallowing (PRS), upper esophageal sphincter (UES), contractile reflex (PUCR), and esophageal body characteristics. Linear mixed and generalized estimating equation models were used for comparison among groups. KEY RESULTS: Compared to controls, HIE infants (Time-1 and Time-2) exhibited decreased number of pharyngeal peaks and latency to terminal swallow. HIE Time-1 infants showed increased UES resting tone and distal latency, compared to controls and HIE Time-2. Contractile vigor was increasingly abnormal during maturation, compared to healthy controls. Threshold volumes and frequency distribution of primary responses (PRS: PUCR: None) were not significant among all groups. CONCLUSIONS & INFERENCES: Compared to controls, HIE infants display significant hypertonicity of skeletal muscle components, impairment of pharyngeal provocation-induced reflexes and smooth muscle contractile vigor, reflecting poor propagation with maturation. These mechanisms may be responsible for inadequate clearance of secretions, ascending refluxate, and oropharyngeal bolus in HIE infants.


Asunto(s)
Asfixia Neonatal/fisiopatología , Desarrollo Infantil/fisiología , Atragantamiento/fisiología , Contracción Muscular/fisiología , Asfixia Neonatal/diagnóstico , Femenino , Humanos , Recién Nacido , Masculino , Manometría/métodos
9.
BMC Musculoskelet Disord ; 18(1): 99, 2017 03 04.
Artículo en Inglés | MEDLINE | ID: mdl-28259162

RESUMEN

BACKGROUND: Clinical swollen joint examination of the obese rheumatoid arthritis (RA) patient can be difficult. Musculoskeletal Ultrasound (MSUS) has higher sensitivity than physical examination for swollen joints (SJ). The purpose of this study was to determine the joint-specific association between power Doppler (PDUS) and clinical SJ in RA across body mass index (BMI) categories. METHODS: Cross-sectional clinical and laboratory data were collected on 43 RA patients. PDUS was performed on 9 joints (wrist, metacarpalphalangeal 2-5, proximal interphalgeal 2/3 and metatarsalphalangeal 2/5). DAS28 and clinical disease activity index (CDAI) were calculated. Patients were categorized by BMI: <25, 25-30, and >30. Demographic and clinical characteristics were compared across BMI groups with Kruskal-Wallis test and chi-square tests. Joint-level associations between PDUS and clinically SJ were evaluated with mixed effects logistic regression models. RESULTS: While demographics and clinically-determined disease activity were similar among BMI groups, PDUS scores significantly differed (p = 0.02). Using PDUS activity as the reference standard for synovitis and clinically SJ as the test, the positive predictive value of SJ was significantly lower in higher BMI groups (0.71 in BMI < 25, 0.58 in BMI 25-30 and 0.44 in BMI < 30) (p = 0.02). The logistic model demonstrated that increased BMI category resulted in decreased likelihood of PDUS positivity (OR 0.52, p = 0.03). CONCLUSIONS: This study suggests that in an obese RA patient, a clinically assessed SJ is less likely to represent true synovitis (as measured by PDUS). Disease activity in obese RA patients may be overestimated by CDAI/DAS28 calculations and clinicians when considering change in therapy.


Asunto(s)
Artritis Reumatoide/diagnóstico por imagen , Obesidad/complicaciones , Sinovitis/diagnóstico por imagen , Adulto , Anciano , Artritis Reumatoide/complicaciones , Femenino , Humanos , Masculino , Persona de Mediana Edad , Sinovitis/etiología , Ultrasonografía Doppler
10.
Neurogastroenterol Motil ; 28(4): 532-42, 2016 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-26727930

RESUMEN

BACKGROUND: Pacifier use is widely prevalent globally despite hygienic concerns and uncertain mechanistic effects on swallowing or airway safety. AIMS: The effects of pacifier and taste interventions on pharyngo-esophageal motility, bolus transit, and respiratory rhythms were investigated by determining the upper esophageal sphincter (UES), esophageal body, esophagogastric junction (EGJ) motor patterns and deglutition apnea, respiratory rhythm disturbances, and esophageal bolus clearance. METHODS: Fifteen infants (six males; median gestation 31 weeks and birth weight 1.4 kg) underwent high-resolution impedance manometry at 43 (41-44) weeks postmenstrual age. Manometric, respiratory, and impedance characteristics of spontaneous swallows, pacifier-associated dry swallowing and taste (pacifier dipped in 3% sucrose)-associated swallowing were analyzed. Linear mixed and generalized estimating equation models were used. Data are presented as mean ± SEM, %, or median (IQR). KEY RESULTS: Pharyngo-esophageal motility, respiratory, and impedance characteristics of 209 swallows were analyzed (85 spontaneous swallows, 63 pacifier- swallows, 61 taste- swallows). Basal UES and EGJ pressures decreased upon pacifier (p < 0.05) and taste interventions (p < 0.05); however, esophageal motility, respiratory rhythm, and impedance transit characteristics were similar with both interventions. CONCLUSIONS & INFERENCES: Oral stimulus with pacifier or taste interventions decreases UES and EGJ basal pressure, but has no effects on pharyngo-esophageal motility, airway interactions, or esophageal bolus transit. A decrease in central parasympathetic-cholinergic excitatory drive is likely responsible for the basal effects.


Asunto(s)
Deglución , Esófago/fisiología , Chupetes , Respiración , Gusto/fisiología , Impedancia Eléctrica , Femenino , Humanos , Recién Nacido , Masculino , Manometría , Peristaltismo/fisiología , Faringe/fisiología
11.
Int J Pharm ; 447(1-2): 1-6, 2013 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-23428880

RESUMEN

Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy has been used to investigate the effects of three fatty acid esters on skin permeation. Propylene glycol diperlargonate (DPPG), isopropyl myristate (IPM) and isostearyl isostearate (ISIS) were selected as pharmaceutically relevant solvents with a range of lipophilicities and cyanophenol (CNP) was used as a model drug. The resultant data were compared with that obtained when water was used as the solvent. The diffusion of CNP, DPPG and IPM across epidermis was successfully described by a Fickian model. When ISIS was used as a solvent Fickian behaviour was only obtained across isolated stratum corneum suggesting that the hydrophilic layers of the epidermis interfere with the permeation of the hydrophobic ISIS. The diffusion coefficients of CNP across epidermis in the different solvents were not significantly different. Using chemometric data analysis diffusion profiles for the solvents were deconvoluted from that of the skin and modelled. Each of these solvents was found to diffuse at a faster rate across the skin than CNP. DPPG considerably increased the concentration of CNP in the stratum corneum in comparison with the other solvents indicating strong penetration enhancer potential. In contrast IPM produced a similar CNP concentration in the stratum corneum to water with ISIS resulting in a lower CNP concentration suggesting negligible enhancement and penetration retardation effects for these two solvents respectively.


Asunto(s)
Ácidos Grasos/administración & dosificación , Fenoles/administración & dosificación , Piel/metabolismo , Solventes/administración & dosificación , Difusión , Ácidos Grasos/química , Femenino , Humanos , Fenoles/química , Absorción Cutánea/efectos de los fármacos , Solventes/química , Espectroscopía Infrarroja por Transformada de Fourier
12.
J Phys Condens Matter ; 24(22): 226003, 2012 Jun 06.
Artículo en Inglés | MEDLINE | ID: mdl-22551672

RESUMEN

Density-functional calculations are employed to investigate the effect of ferroelectric polarization of BaTiO(3) on the magnetocrystalline anisotropy of the Fe /BaTiO(3)(001) interface. It is found that the interface magnetocrystalline anisotropy energy changes from 1.33 to 1.02 erg cm (-2) when the ferroelectric polarization is reversed. This strong magnetoelectric coupling is explained in terms of the changing population of the Fe 3d orbitals at the Fe/BaTiO(3) interface driven by polarization reversal. Our results indicate that the electronically assisted magnetoelectric effects at the ferromagnetic/ferroelectric interfaces may be a viable alternative to the strain mediated coupling in related heterostructures and the electric field-induced effects on the interface magnetic anisotropy in ferromagnet/dielectric structures.

13.
J Phys Condens Matter ; 24(9): 096002, 2012 Mar 07.
Artículo en Inglés | MEDLINE | ID: mdl-22317897

RESUMEN

Magnetoresistance (MR) measurements are carried out on a Co(8 nm)/CoO(3.5 nm) bilayer in the exchange bias (EB) state prepared by molecular beam epitaxy. With the applied magnetic field parallel to the current, the EB MR curves show an asymmetric behavior about the minimum, in contrast to the symmetric one for non-EB systems. We generalize a well-known analytical expression used for the field dependence of the MR of paramagnets. Our generalization incorporates coercivity and EB in a new phenomenological MR expression. Excellent fits of the latter to the experimental MR data are achieved, showing the way to use MR techniques for the quantitative characterization of EB systems. Furthermore, the temperature dependence of the EB field obtained from MR loops can be described with a power law, which yields a value of 96.6 K for the EB blocking temperature, which is significantly below the Néel temperature of 293 K for bulk CoO.


Asunto(s)
Cobalto/química , Campos Magnéticos , Óxidos/química , Temperatura
14.
Phys Rev Lett ; 109(24): 247601, 2012 Dec 14.
Artículo en Inglés | MEDLINE | ID: mdl-23368377

RESUMEN

We explore the effect of charge carrier doping on ferroelectricity using density functional calculations and phenomenological modeling. By considering a prototypical ferroelectric material, BaTiO(3), we demonstrate that ferroelectric displacements are sustained up to the critical concentration of 0.11 electron per unit cell volume. This result is consistent with experimental observations and reveals that the ferroelectric phase and conductivity can coexist. Our investigations show that the ferroelectric instability requires only a short-range portion of the Coulomb force with an interaction range of the order of the lattice constant. These results provide a new insight into the origin of ferroelectricity in displacive ferroelectrics and open opportunities for using doped ferroelectrics in novel electronic devices.

15.
Phys Rev Lett ; 103(1): 016804, 2009 Jul 03.
Artículo en Inglés | MEDLINE | ID: mdl-19659167

RESUMEN

The demonstration of a quasi-two-dimensional electron gas (2DEG) in LaAlO3/SrTiO3 heterostructures has stimulated intense research activity in recent years. The 2DEG has unique properties that are promising for applications in all-oxide electronic devices. For such applications it is desirable to have the ability to control 2DEG properties by external stimulus. Here, based on first-principles calculations we predict that all-oxide heterostructures incorporating ferroelectric constituents, such as KNbO3/ATiO3 (A=Sr, Ba, Pb), allow creating a 2DEG switchable between two conduction states by ferroelectric polarization reversal. The effect occurs due to the screening charge at the interface that counteracts the depolarizing electric field and depends on polarization orientation. The proposed concept of ferroelectrically controlled interface conductivity offers the possibility to design novel electronic devices.

16.
Nano Lett ; 6(3): 483-7, 2006 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-16522047

RESUMEN

Interfaces play a critical role in nanoscale ferroelectricity. We perform a first-principles study of ultrathin KNbO(3) ferroelectric films placed between two metal electrodes, either SrRuO(3) or Pt. We show that bonding at the ferroelectric-metal interfaces imposes severe constraints on the displacement of atoms, destroying the bulk tetragonal soft mode. If the interface bonding is sufficiently strong, the ground-state represents a ferroelectric domain with an interface domain wall, driven by the intrinsic oppositely oriented dipole moments at the two interfaces. The critical thickness for the net polarization of the KNbO(3) film is predicted to be about 1 nm for Pt and 1.8 nm for SrRuO(3) electrodes.

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