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1.
Nature ; 627(8002): 67-72, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-38448698

RESUMEN

Ordinary metals contain electron liquids within well-defined 'Fermi' surfaces at which the electrons behave as if they were non-interacting. In the absence of transitions to entirely new phases such as insulators or superconductors, interactions between electrons induce scattering that is quadratic in the deviation of the binding energy from the Fermi level. A long-standing puzzle is that certain materials do not fit this 'Fermi liquid' description. A common feature is strong interactions between electrons relative to their kinetic energies. One route to this regime is special lattices to reduce the electron kinetic energies. Twisted bilayer graphene1-4 is an example, and trihexagonal tiling lattices (triangular 'kagome'), with all corner sites removed on a 2 × 2 superlattice, can also host narrow electron bands5 for which interaction effects would be enhanced. Here we describe spectroscopy revealing non-Fermi-liquid behaviour for the ferromagnetic kagome metal Fe3Sn2 (ref. 6). We discover three C3-symmetric electron pockets at the Brillouin zone centre, two of which are expected from density functional theory. The third and most sharply defined band emerges at low temperatures and binding energies by means of fractionalization of one of the other two, most likely on the account of enhanced electron-electron interactions owing to a flat band predicted to lie just above the Fermi level. Our discovery opens the topic of how such many-body physics involving flat bands7,8 could differ depending on whether they arise from lattice geometry or from strongly localized atomic orbitals9,10.

2.
Nano Lett ; 23(14): 6433-6439, 2023 Jul 26.
Artículo en Inglés | MEDLINE | ID: mdl-37460109

RESUMEN

Black phosphorus (BP) stands out among two-dimensional (2D) semiconductors because of its high mobility and thickness dependent direct band gap. However, the quasiparticle band structure of ultrathin BP has remained inaccessible to experiment thus far. Here we use a recently developed laser-based microfocus angle resolved photoemission (µ-ARPES) system to establish the electronic structure of 2-9 layer BP from experiment. Our measurements unveil ladders of anisotropic, quantized subbands at energies that deviate from the scaling observed in conventional semiconductor quantum wells. We quantify the anisotropy of the effective masses and determine universal tight-binding parameters, which provide an accurate description of the electronic structure for all thicknesses.

3.
Nano Lett ; 19(1): 554-560, 2019 01 09.
Artículo en Inglés | MEDLINE | ID: mdl-30570259

RESUMEN

Two-dimensional crystals of semi-metallic van der Waals materials hold much potential for the realization of novel phases, as exemplified by the recent discoveries of a polar metal in few-layer 1T'-WTe2 and of a quantum spin Hall state in monolayers of the same material. Understanding these phases is particularly challenging because little is known from experiments about the momentum space electronic structure of ultrathin crystals. Here, we report direct electronic structure measurements of exfoliated mono-, bi-, and few-layer 1T'-WTe2 by laser-based microfocus angle-resolved photoemission. This is achieved by encapsulating with monolayer graphene a flake of WTe2 comprising regions of different thickness. Our data support the recent identification of a quantum spin Hall state in monolayer 1T'-WTe2 and reveal strong signatures of the broken inversion symmetry in the bilayer. We finally discuss the sensitivity of encapsulated samples to contaminants following exposure to ambient atmosphere.

4.
Hawaii J Health Soc Welf ; 81(10): 279-286, 2022 10.
Artículo en Inglés | MEDLINE | ID: mdl-36212220

RESUMEN

Increasing numbers of medical students participate in international electives. However, this recent trend has yet to be examined in non-Western high-income countries such as Japan. The aim of this study is to assess recent trends in Japan, and to suggest ways in which those trends might be influenced. A retrospective cross-sectional analysis of responses to an 8-item questionnaire sent in August 2019 to 82 medical schools in Japan is reported. The responses were received in September 2019. Narrative responses were obtained regarding rationales for exchange programs, participant feedback, and challenges encountered. Responses were translated into English and categorized into themes. Of 82 Japanese medical schools, 56 (68%) responded to the questionnaire. Both the number of incoming and outgoing exchange students had increased steadily over the preceding 3-year period. The leading destinations for Japanese students were the United States (30%), other Asian (36%), and European countries (24%). Narrative responses reveal different rationales from those reported by medical schools in Western high-income countries. Only a few Japanese students chose low or middle-income countries as their destinations, as opposed to the trend seen in Western high-income countries. The reported challenges encountered by the exchange programs may provide insights for improvement. Exchanges have been greatly affected by the coronavirus disease 2019 pandemic. The results can serve as pre-pandemic baseline data and should promote further international collaboration for medical education under current circumstances.


Asunto(s)
COVID-19 , Educación Médica , Estudiantes de Medicina , Estudios Transversales , Humanos , Japón , Estudios Retrospectivos , Estados Unidos
5.
J Diabetes Investig ; 13(7): 1277-1285, 2022 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-35243802

RESUMEN

AIMS/INTRODUCTION: Diabetes mellitus is reported as a risk factor for increased coronavirus disease 2019 (COVID-19) severity and mortality, but there have been few reports from Japan. Associations between diabetes mellitus and COVID-19 severity and mortality were investigated in a single Japanese hospital. MATERIALS AND METHODS: Patients aged ≥20 years admitted to Osaka City General Hospital for COVID-19 treatment between April 2020 and March 2021 were included in this retrospective, observational study. Multivariable logistic regression analysis was carried out to examine whether diabetes mellitus contributes to COVID-19-related death and severity. RESULTS: Of the 262 patients included, 108 (41.2%) required invasive ventilation, and 34 (13.0%) died in hospital. The diabetes group (n = 92) was significantly older, more obese, had longer hospital stays, more severe illness and higher mortality than the non-diabetes group (n = 170). On multivariable logistic regression analysis, age (odds ratio [OR] 1.054, 95% confidence interval [CI] 1.023-1.086), body mass index (OR 1.111, 95% CI 1.028-1.201), history of diabetes mellitus (OR 2.429, 95% CI 1.152-5.123), neutrophil count (OR 1.222, 95% CI 1.077-1.385), C-reactive protein (OR 1.096, 95% CI 1.030-1.166) and Krebs von den Lungen-6 (OR 1.002, 95% CI 1.000-1.003) were predictors for COVID-19 severity (R2 = 0.468). Meanwhile, age (OR 1.104, 95% CI 1.037-1.175) and Krebs von den Lungen-6 (OR 1.003, 95% CI 1.001-1.005) were predictors for COVID-19-related death (R2 = 0.475). CONCLUSIONS: Diabetes mellitus was a definite risk factor for COVID-19 severity in a single Japanese hospital treating moderately-to-severely ill patients.


Asunto(s)
Tratamiento Farmacológico de COVID-19 , COVID-19 , Diabetes Mellitus , Factores de Edad , COVID-19/complicaciones , COVID-19/epidemiología , Diabetes Mellitus/epidemiología , Humanos , Japón/epidemiología , Estudios Retrospectivos , Factores de Riesgo , SARS-CoV-2 , Índice de Severidad de la Enfermedad
6.
Hawaii J Health Soc Welf ; 79(6 Suppl 2): 82-88, 2020 06 01.
Artículo en Inglés | MEDLINE | ID: mdl-32596684

RESUMEN

Little is known about Marshallese palliative care practices. We explored traditional and contemporary Marshallese palliative care practices and examined generational differences. We performed three focus groups in 2011-2012 among Marshall Islanders in Hawai'i. A native speaking interpreter assisted group facilitators. Data were analyzed using classical thematic triangulation methods to identify specific Marshallese palliative care practices, the effect of economic and social challenges in Hawai'i, and generational differences comparing young and old. Nineteen persons (10 men and 9 women, youth aged 17-27 years, and elders as defined in Marshallese culture, aged 46-79) participated. A "good death" was defined as "peaceful and pain free," occurring from natural causes. Factors associated with a "good death" included gathering of family to absolve conflicts, and proper and timely cultural practices. Factors associated with "bad deaths" included young age, active suffering, accidents, suicides, "black magic/curses," or lack of timely or proper burial. Comparing generational differences, older Marshallese had differing opinions regarding preferred place of death, burial site, cultural practice preservation, artificial prolongation of life, and cremation. Barriers included mortuary fees, cost of transporting bodies, United States (US) government policies, and wait times for death certificates. Many cultural factors contribute to "good" or "bad" deaths. Attitudes toward palliative care practices differ by generation. Having previously documented different approaches by Yapese, a generalized "one size fits all" approach to Micronesians is inappropriate. Overcoming identified barriers may facilitate practices necessary for a good death in Micronesian populations in their home nations and as they migrate to communities throughout the US.


Asunto(s)
Asistencia Sanitaria Culturalmente Competente/normas , Composición Familiar , Cuidados Paliativos/métodos , Adolescente , Adulto , Anciano , Actitud Frente a la Muerte , Asistencia Sanitaria Culturalmente Competente/estadística & datos numéricos , Femenino , Grupos Focales/métodos , Hawaii , Humanos , Masculino , Micronesia/etnología , Persona de Mediana Edad , Cuidados Paliativos/tendencias , Investigación Cualitativa
7.
Nat Mater ; 7(5): 367-71, 2008 May.
Artículo en Inglés | MEDLINE | ID: mdl-18425134

RESUMEN

C(60)-based solids are archetypal molecular superconductors with transition temperatures (Tc) as high as 33 K (refs 2-4). Tc of face-centred-cubic (f.c.c.) A(3)C(60) (A=alkali metal) increases monotonically with inter C(60) separation, which is controlled by the A(+) cation size. As Cs(+) is the largest such ion, Cs(3)C(60) is a key material in this family. Previous studies revealing trace superconductivity in Cs(x)C(60) materials have not identified the structure or composition of the superconducting phase owing to extremely small shielding fractions and low crystallinity. Here, we show that superconducting Cs(3)C(60) can be reproducibly isolated by solvent-controlled synthesis and has the highest Tc of any molecular material at 38 K. In contrast to other A(3)C(60) materials, two distinct cubic Cs(3)C(60) structures are accessible. Although f.c.c. Cs(3)C(60) can be synthesized, the superconducting phase has the A15 structure based uniquely among fullerides on body-centred-cubic packing. Application of hydrostatic pressure controllably tunes A15 Cs(3)C(60) from insulating at ambient pressure to superconducting without crystal structure change and reveals a broad maximum in Tc at approximately 7 kbar. We attribute the observed Tc maximum as a function of inter C(60)separation--unprecedented in fullerides but reminiscent of the atom-based cuprate superconductors--to the role of strong electronic correlations near the metal-insulator transition onset.

9.
Diabetes Metab Syndr ; 12(2): 203-206, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-29208515

RESUMEN

An 83-year-old man developed hypoglycemia after undergoing total gastrectomy for gastric cancer in 200X-4. The patient was admitted to our hospital in May 200X and placed on continuous glucose monitoring (CGM). Glycemic excursions were examined while on 3-meal/day (1700kcal) and 6-meal/day (1800kcal) diets. Oxyhyperglycemia followed about 2h later by a sudden drop in glucose levels was seen with both regimens. These findings were consistent with late dumping syndrome. CGM was continued, oral miglitol at 150mg/day or sitagliptin at 50mg/day was started, and glycemic excursions were compared. Results were similar for both drugs, with reductions in postprandial glucose elevations. Meal tolerance testing 3 months after oral sitagliptin, compared to before starting treatment, showed reductions in both early postprandial hyperglycemia and insulin hypersecretion. These findings suggest that DPP-4 inhibitors such as sitagliptin may be effective for treating post-gastrectomy late dumping syndrome.


Asunto(s)
Inhibidores de la Dipeptidil-Peptidasa IV/uso terapéutico , Síndrome de Vaciamiento Rápido/tratamiento farmacológico , Gastrectomía/efectos adversos , Complicaciones Posoperatorias/tratamiento farmacológico , Fosfato de Sitagliptina/uso terapéutico , Anciano de 80 o más Años , Síndrome de Vaciamiento Rápido/diagnóstico , Síndrome de Vaciamiento Rápido/etiología , Humanos , Masculino , Complicaciones Posoperatorias/diagnóstico , Complicaciones Posoperatorias/etiología , Resultado del Tratamiento
10.
J Diabetes ; 7(1): 41-6, 2015 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-24661437

RESUMEN

BACKGROUND: We investigated the change in the urine albumin-to-creatinine ratio (ACR) to examine the effect of sitagliptin on diabetic nephropathy. METHODS: Sitagliptin at a dose of 50 mg was administered to 247 outpatients with type 2 diabetes. Data were collected on the patients' laboratory results (including the ACR), blood pressure, and body weight. Clinical data were compared before and after 3 months' administration of sitagliptin. RESULTS: The ACR changed from 150.0 ± 538.6 mg/gCre to 148.3 ± 764.6 mg/gCre over 3 months. In the patients with micro- and macro-albuminuria, the ACR after 3 months significantly decreased compared with the baseline (P = 0.04 and P = 0.02, respectively). The subjects whose ACR decreased experienced significantly larger decreases over the 3-month period in blood pressure and estimated glomerular filtration rate (eGFR) than the other subjects. There was no significant correlation between change in ACR (ΔACR) and change in hemoglobin A1c (ΔHbA1c) during 3 months (r = 0.04, P = 0.59), but there was a significant correlation between change in ΔACR and change in systolic blood pressure (r = 0.16, P = 0.03). Multiple regression analysis revealed that the significant predictors for ΔACR were change in systolic blood pressure (ß = 0.21, P = 0.016) and change in eGFR (ß = 0.20, P = 0.024) over 3 months (r = 0.35, P = 0.04). CONCLUSIONS: Sitagliptin reduces the ACR through decreasing both blood pressure and eGFR, with no correlation with a decrease in HbA1c over a 3-month period. These results may reflect the direct action of sitagliptin on the kidneys.


Asunto(s)
Albuminuria/prevención & control , Presión Sanguínea/efectos de los fármacos , Creatinina/orina , Diabetes Mellitus Tipo 2/tratamiento farmacológico , Nefropatías Diabéticas/tratamiento farmacológico , Hipoglucemiantes/uso terapéutico , Pirazinas/uso terapéutico , Triazoles/uso terapéutico , Diabetes Mellitus Tipo 2/complicaciones , Diabetes Mellitus Tipo 2/fisiopatología , Nefropatías Diabéticas/etiología , Nefropatías Diabéticas/fisiopatología , Femenino , Tasa de Filtración Glomerular , Hemoglobina Glucada/análisis , Humanos , Pruebas de Función Renal , Masculino , Persona de Mediana Edad , Fosfato de Sitagliptina
11.
Adv Mater ; 27(26): 3894-9, 2015 Jul 08.
Artículo en Inglés | MEDLINE | ID: mdl-26010071

RESUMEN

The origin of the 2D electron gas (2DEG)stabilized at the bare surface of SrTiO3 (001) is investigated. Using high-resolution angle-resolved photoemission and core-level spectroscopy, it is shown conclusively that this 2DEG arises from light-induced oxygen vacancies. The dominant mechanism driving vacancy formation is identified, allowing unprecedented control over the 2DEG carrier density.

12.
Intern Med ; 53(19): 2211-4, 2014.
Artículo en Inglés | MEDLINE | ID: mdl-25274232

RESUMEN

We encountered a case of epithelioid inflammatory myofibroblastic sarcoma (EIMS) originating from an abdominal organ that rapidly regrew twice. The patient underwent two surgeries. Large tumors grew within three months after the second surgery. The patient subsequently received chemotherapy with an anaplastic lymphoma kinase (ALK) inhibitor. Although EIMS has a poor prognosis, the patient continues to be alive with disease 14 months after surgical treatment and the administration of the ALK inhibitor.


Asunto(s)
Inhibidores Enzimáticos/uso terapéutico , Hipopituitarismo/complicaciones , Neoplasias Intestinales/terapia , Laparotomía/métodos , Proteínas Tirosina Quinasas Receptoras/antagonistas & inhibidores , Sarcoma/terapia , Quinasa de Linfoma Anaplásico , Colonoscopía , Terapia Combinada , Estudios de Seguimiento , Humanos , Hipopituitarismo/diagnóstico , Neoplasias Intestinales/complicaciones , Neoplasias Intestinales/diagnóstico , Intestino Delgado , Masculino , Proteínas Tirosina Quinasas Receptoras/metabolismo , Sarcoma/complicaciones , Sarcoma/diagnóstico , Tomografía Computarizada por Rayos X , Adulto Joven
14.
J Am Geriatr Soc ; 61(11): 1953-7, 2013 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-24117324

RESUMEN

OBJECTIVES: To provide the first report on prevalence of vitamin D deficiency in newly admitted nursing home (NH) residents and associations with functional disabilities and chronic diseases. DESIGN: Retrospective chart review. SETTING: Nursing home (NH). PARTICIPANTS: Male veterans newly admitted to a NH for rehabilitation, skilled-nursing care, intermediate care, or respite care between January 2011 and June 2012. MEASUREMENTS: Total serum 25-hydroxyvitamin D (25(OH)D) levels were measured on admission. Vitamin D supplement users and those without 25(OH)D measurement within 7 days of admission were excluded, leaving an analytical sample of 104 residents. Vitamin D deficiency was defined as 25(OH)D less than 20 ng/mL. Data were collected on age, ethnicity, season, body mass index (BMI), functional disability in activities of daily living (ADLs) (mobility, bathing, dressing, toileting, continence, and feeding), and prevalent chronic diseases. RESULTS: Prevalence of vitamin D deficiency was 49.0%. In multivariate logistic regression models adjusted for age, ethnicity, and BMI, vitamin D deficiency was significantly associated with number of ADL disabilities (odds ratio (OR) = 1.4 for each 1-point increase in ADL disability score, P = .03) and prevalent diabetes mellitus (OR = 3.0, P = .03). In regression models using each ADL disability as a separate variable, only disability in feeding (OR = 4.7, P = .05) and diabetes mellitus (OR = 2.9, P = .04) remained significant. CONCLUSION: Almost half the individuals entering the NH and not taking vitamin D supplements had vitamin D deficiency. Greater number of ADL disabilities, disability in feeding, and prevalent diabetes mellitus were independently associated with vitamin D deficiency.


Asunto(s)
Actividades Cotidianas , Casas de Salud , Deficiencia de Vitamina D/epidemiología , Enfermedad Crónica/epidemiología , Evaluación de la Discapacidad , Humanos , Masculino , Prevalencia , Estudios Retrospectivos , Veteranos
16.
Science ; 303(5655): 217-20, 2004 Jan 09.
Artículo en Inglés | MEDLINE | ID: mdl-14716010

RESUMEN

A highly regular mesh of hexagonal boron nitride with a 3-nanometer periodicity and a 2-nanometer hole size was formed by self-assembly on a Rh(111) single crystalline surface. Two layers of mesh cover the surface uniformly after high-temperature exposure of the clean rhodium surface to borazine (HBNH)3. The two layers are offset in such a way as to expose a minimum metal surface area. Hole formation is likely driven by the lattice mismatch of the film and the rhodium substrate. This regular nanostructure is thermally very stable and can serve as a template to organize molecules, as is exemplified by the decoration of the mesh by C60 molecules.

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