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1.
Nat Commun ; 15(1): 4413, 2024 May 23.
Artículo en Inglés | MEDLINE | ID: mdl-38782910

RESUMEN

In Josephson diodes the asymmetry between positive and negative current branch of the current-phase relation leads to a polarity-dependent critical current and Josephson inductance. The supercurrent nonreciprocity can be described as a consequence of the anomalous Josephson effect -a φ0-shift of the current-phase relation- in multichannel ballistic junctions with strong spin-orbit interaction. In this work, we simultaneously investigate φ0-shift and supercurrent diode efficiency on the same Josephson junction by means of a superconducting quantum interferometer. By electrostatic gating, we reveal a direct link between φ0-shift and diode effect. Our findings show that spin-orbit interaction in combination with a Zeeman field plays an important role in determining the magnetochiral anisotropy and the supercurrent diode effect.

2.
Nat Nanotechnol ; 18(11): 1266-1272, 2023 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-37430040

RESUMEN

The recent discovery of the intrinsic supercurrent diode effect, and its prompt observation in a rich variety of systems, has shown that non-reciprocal supercurrents naturally emerge when both space-inversion and time-inversion symmetries are broken. In Josephson junctions, non-reciprocal supercurrent can be conveniently described in terms of spin-split Andreev states. Here we demonstrate a sign reversal of the Josephson inductance magnetochiral anisotropy, a manifestation of the supercurrent diode effect. The asymmetry of the Josephson inductance as a function of the supercurrent allows us to probe the current-phase relation near equilibrium, and to probe jumps in the junction ground state. Using a minimal theoretical model, we can then link the sign reversal of the inductance magnetochiral anisotropy to the so-called 0-π-like transition, a predicted but still elusive feature of multichannel junctions. Our results demonstrate the potential of inductance measurements as sensitive probes of the fundamental properties of unconventional Josephson junctions.

3.
J Phys Condens Matter ; 34(15)2022 Feb 10.
Artículo en Inglés | MEDLINE | ID: mdl-35051919

RESUMEN

Simultaneous breaking of inversion- and time-reversal symmetry in Josephson junction (JJ) leads to a possible violation of theI(φ) = -I(-φ) equality for the current-phase relation. This is known as anomalous Josephson effect and it produces a phase shiftφ0in sinusoidal current-phase relations. In ballistic JJs with non-sinusoidal current phase relation the observed phenomenology is much richer, including the supercurrent diode effect and the magnetochiral anisotropy (MCA) of Josephson inductance. In this work, we present measurements of both effects on arrays of JJs defined on epitaxial Al/InAs heterostructures. We show that the orientation of the current with respect to the lattice affects the MCA, possibly as the result of a finite Dresselhaus component. In addition, we show that the two-fold symmetry of the Josephson inductance reflects in the activation energy for phase slips.

4.
J Vestib Res ; 31(3): 173-180, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33522991

RESUMEN

BACKGROUND: Dizziness affects 20-30%of the general population. A subgroup of dizzy patients with chronic migraine suffers vertigo implying that the migraine has a vestibular component. Vestibular migraine remains a diagnosis of exclusion based on history. OBJECTIVE: A link between headaches and dizziness suggests that these individuals would demonstrate dizziness and instability in complex, dynamic visual environments as a result of an inability to correctly process conflicting visual and vestibular signals. METHODS: A convenience sample of 74 patients (22 men and 52 women; average age 56.2 years) who presented with complaints of dizziness participated. Effects of Visual-Vestibular Mismatch (VVM) were measured using a modified VVM questionnaire. Visual dependence was measured as the error to subjective visual vertical using a computerized Rod and Frame test. RESULTS: Forty-two participants (56.8%) tested positive for VVM. Of these, 68.9%were patients with concomitant complaints of headaches. Visual dependence was present in 41.5%of all patients but showed no significant correlation with headache. 22.2%of patients had visual dependence and complained of headaches. CONCLUSIONS: These results demonstrate that sensory reweighting occurs in patients experiencing dizziness and headache, supports the role of vestibular involvement in this disorder, and provides future direction for novel interventions.


Asunto(s)
Trastornos Migrañosos , Vértigo , Mareo , Femenino , Cefalea , Humanos , Masculino , Persona de Mediana Edad , Trastornos Migrañosos/complicaciones , Trastornos Migrañosos/diagnóstico
6.
Rev. chil. infectol ; 37(6)dic. 2020.
Artículo en Español | LILACS | ID: biblio-1388184

RESUMEN

Resumen Introducción: Enterocolitis necrosante (ECN) representa una elevada mortalidad y morbilidad post-quirúrgica, gastrointestinal y del neuro-desarrollo. Existe limitada información en Chile. Objetivo: Describir el comportamiento clínico/epidemiológico de recién nacidos que cursaron con ECN. Pacientes y Métodos: Estudio multicéntrico descriptivo de pacientes con ECN de siete hospitales de Santiago, Chile, durante el 2016. Se realizó estadística descriptiva y análisis univariable/multivariable (software SPSS v22). Resultados: Se recolectaron 75 casos. Mediana de edad al diagnóstico fue 11 días, el promedio de edad gestacional 29 semanas y peso de nacimiento 1.285 g. La incidencia fue 2,6 por 1.000/recién nacidos vivos y letalidad de 18,6%, mayor en ≤ 750 g, ≤ 25 semanas y ECN quirúrgica. Hubo aislamiento microbiológico en 45,3% y se utilizaron 19 distintos esquemas antimicrobianos empíricos para el tratamiento de ECN. El análisis multivariable mostró tendencia a que la ECN fuese quirúrgica en usuarios de catéter umbilical arterial, PCR > 10 mg/L y aislamiento microbiológico, y hubo tendencia a fallecer en usuarios de catéter umbilical arterial. Discusión: Es el primer estudio multicéntrico que recopila información de datos locales. La incidencia fue similar a la descrita en la literatura médica, en cambio la letalidad fue algo menor. No existen consensos del tratamiento antimicrobiano a utilizar. Con estos resultados esperamos avanzar en mejorar el diagnóstico y unificar tratamientos antimicrobianos, para reducir cifras de morbimortalidad.


Abstract Background: Necrotizing enterocolitis (NEC) presents high mortality and postoperative, gastrointestinal and neurodevelopmental morbidity. There is limited information about NEC in Chile. Aim: To describe the clinical/epidemiological behavior of newborns who underwent NEC. Methods: Multicenter descriptive study of patients with NEC from seven hospitals of Santiago, Chile, during 2016. Descriptive statistics and univariate/multivariate analysis were performed (SPSS v22 software). Results: 75 cases were collected. Median days of life at diagnosis was 11, gestational age was 29 weeks, birth weight 1,114 g. The incidence was 2.6 per 1,000 live newborns and mortality was 18.6%, higher in ≤ 750 g, ≤ 25 weeks and surgical NEC. There was 45.3% microbiological isolation and 19 different empirical antibiotic schemes were used for the treatment of NEC. The multivariate analysis showed a higher risk of surgery in umbilical arterial catheter users, CRP > 10 mg/L and positive microbiological isolation. The highest risk of death was in umbilical arterial catheter users. Discussion: This ie the first multicenter study that collects local data information. The incidence was similar to that found in medical reports but with a lower mortality. There is no consensus of antibiotic treatment to use. With these results we hope to advance in improving the diagnosis and unify antimicrobial treatments, to reduce morbidity and mortality figures.


Asunto(s)
Humanos , Lactante , Recién Nacido , Enterocolitis Necrotizante , Chile/epidemiología , Estudios Retrospectivos , Factores de Riesgo , Edad Gestacional , Enterocolitis Necrotizante/epidemiología , Hospitales Públicos
7.
J Int Adv Otol ; 16(3): 463-466, 2020 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-33136029

RESUMEN

The stapedial artery is an embryologic structure that very rarely persists into adulthood. Termed the persistent stapedial artery (PSA), it is most often asymptomatic, identified retrospectively, and can complicate middle ear surgery. A 70-year-old woman presented with profound bilateral sensorineural hearing loss and elected to undergo cochlear implantation. During surgery, a pulsatile, cord-like structure was found obscuring the round window niche. A high-resolution computed tomography (HRCT) imaging review confirmed PSA diagnosis. A cochleostomy was made using a cochleostomy burr and gentle vessel compression. Complete insertion of the cochlear implant was achieved and its placement confirmed. The patient went on to develop open-set discrimination. We report the first successful case of cochlear implantation in the face of a PSA. Inverted HRCT imaging was found to enhance PSA visualization and may aid preoperative diagnosis. A cochleostomy technique is recommended for electrode insertion to minimize the risk of bleeding.


Asunto(s)
Implantación Coclear , Implantes Cocleares , Adulto , Anciano , Arterias , Cóclea/cirugía , Femenino , Humanos , Estudios Retrospectivos , Ventana Redonda/cirugía
8.
Am J Otolaryngol ; 41(3): 102402, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-31982210

RESUMEN

PURPOSE: Suspension laryngoscopy is a commonly performed procedure in otolaryngology. During the procedure, the laryngoscope applies direct force to the tongue. Postoperative tongue symptoms include pain, swelling, numbness, taste disturbance, and rarely motor deficits. Duration and magnitude of force applied have previously been associated with post-operative throat and tongue pain, respectively. We sought to correlate postoperative tongue symptoms with magnitude of force applied and/or duration of suspension and investigate any risk factors for tongue morbidity. MATERIALS AND METHODS: A sample of patients undergoing suspension laryngoscopy between 2015 and 2018 were prospectively recruited. Those with preexisting tongue symptoms, disease or surgery were excluded. Patients completed preoperative and postoperative questionnaires evaluating tongue swelling, numbness, motion and taste disturbance. Symptoms were subjectively scored on a visual scale from 0 to 10. Patient demographics, past medical and social history were also recorded. Intraoperative pressures were measured using a spring force scale, positioned between the suspension arm and Mayo stand. Initial and end suspension forces and duration of suspension were recorded. RESULTS: 120 patients met inclusion criteria, of which 63 completed both preoperative and postoperative questionnaires. 6 patients (9.5%) experienced postoperative tongue symptoms. Suspension force and duration of suspension were not significantly predictive of postoperative tongue symptoms. While all symptomatic patients were current or former cigarette smokers, smoking status was not found to be a statistically significant factor. CONCLUSIONS: Neither suspension forces nor duration of suspension were predictive of postoperative tongue morbidity. Further research is needed to evaluate the role of smoking status on postoperative tongue symptoms.


Asunto(s)
Hipoxia/etiología , Hipoxia/patología , Laringoscopía/efectos adversos , Resultados Negativos , Complicaciones Posoperatorias/etiología , Complicaciones Posoperatorias/patología , Presión/efectos adversos , Enfermedades de la Lengua/etiología , Enfermedades de la Lengua/patología , Lengua/patología , Adulto , Anciano , Fenómenos Biomecánicos , Edema , Femenino , Humanos , Hipoxia/fisiopatología , Periodo Intraoperatorio , Masculino , Persona de Mediana Edad , Movimiento (Física) , Dolor , Complicaciones Posoperatorias/fisiopatología , Factores de Riesgo , Encuestas y Cuestionarios , Gusto , Lengua/fisiopatología , Enfermedades de la Lengua/fisiopatología , Adulto Joven
9.
Rev Chilena Infectol ; 37(6): 667-674, 2020 Dec.
Artículo en Español | MEDLINE | ID: mdl-33844806

RESUMEN

BACKGROUND: Necrotizing enterocolitis (NEC) presents high mortality and postoperative, gastrointestinal and neurodevelopmental morbidity. There is limited information about NEC in Chile. AIM: To describe the clinical/epidemiological behavior of newborns who underwent NEC. METHODS: Multicenter descriptive study of patients with NEC from seven hospitals of Santiago, Chile, during 2016. Descriptive statistics and univariate/multivariate analysis were performed (SPSS v22 software). RESULTS: 75 cases were collected. Median days of life at diagnosis was 11, gestational age was 29 weeks, birth weight 1,114 g. The incidence was 2.6 per 1,000 live newborns and mortality was 18.6%, higher in ≤ 750 g, ≤ 25 weeks and surgical NEC. There was 45.3% microbiological isolation and 19 different empirical antibiotic schemes were used for the treatment of NEC. The multivariate analysis showed a higher risk of surgery in umbilical arterial catheter users, CRP > 10 mg/L and positive microbiological isolation. The highest risk of death was in umbilical arterial catheter users. DISCUSSION: This ie the first multicenter study that collects local data information. The incidence was similar to that found in medical reports but with a lower mortality. There is no consensus of antibiotic treatment to use. With these results we hope to advance in improving the diagnosis and unify antimicrobial treatments, to reduce morbidity and mortality figures.


Asunto(s)
Enterocolitis Necrotizante , Chile/epidemiología , Enterocolitis Necrotizante/epidemiología , Edad Gestacional , Hospitales Públicos , Humanos , Lactante , Recién Nacido , Estudios Retrospectivos , Factores de Riesgo
10.
Phys Rev Lett ; 85(9): 1819-22, 2000 Aug 28.
Artículo en Inglés | MEDLINE | ID: mdl-10970622

RESUMEN

Excitation functions A(N)(p(p),Theta(c.m.)) of the analyzing power in pp--> elastic scattering have been measured with a polarized atomic hydrogen target for projectile momenta p(p) between 1000 and 3300 MeV/ c. The experiment was performed for scattering angles 30 degrees

11.
Fresenius J Anal Chem ; 368(2-3): 214-20, 2000.
Artículo en Inglés | MEDLINE | ID: mdl-11220582

RESUMEN

The stability of arsenic, selenium, antimony and tellurium species in water and urine (NIST SRM 2670n) as well as in extracts of fish and soil certified reference materials (DORM-2 and NIST SRM 2710) has been investigated. Stability studies were carried out with As(III), As(V), arsenobetaine, monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), phenylarsonic acid (PAA), Se(IV), Se(VI), selenomethionine, Sb(III), Sb(V) and Te(VI). Speciation analysis was performed by on-line coupling of anion exchange high-performance liquid chromatography (HPLC) with inductively coupled plasma mass spectrometry (ICP-MS). Best storage of aqueous mixtures of the examined species was achieved at 3 degrees C whereas at -20 degrees C species transformation especially of selenomethionine and Sb(V) took place and a new selenium species appeared within a period of 30 days. Losses and species transformations during extraction processes were investigated. Extraction of the spiked fish material with methanol/water led to partial conversion of Sb(III), Sb(V) and selenomethionine to two new antimony and one new selenium species. The other arsenic, selenium and tellurium species were almost quantitatively extracted. For soil spiked with MMA, PAA, Se(IV) and Sb(III), recoveries after extraction with water and sulfuric acid (0.01 mol/L) were below 20%.


Asunto(s)
Cromatografía Líquida de Alta Presión/métodos , Peces , Espectrometría de Masas/métodos , Metales/análisis , Suelo/análisis , Agua/química , Animales , Antimonio/análisis , Arsénico/análisis , Selenio/análisis , Telurio/análisis
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