RESUMEN
The recent implementation of attosecond and few-femtosecond X-ray pump/X-ray probe schemes in large-scale free-electron laser facilities has opened the way to visualize fast nuclear dynamics in molecules with unprecedented temporal and spatial resolution. Here, we present the results of theoretical calculations showing how polarization-averaged molecular-frame photoelectron angular distributions (PA-MFPADs) can be used to visualize the dynamics of hydrogen migration in methanol, ethanol, propanol, and isopropyl alcohol dications generated by X-ray irradiation of the corresponding neutral species. We show that changes in the PA-MFPADs with the pump-probe delay as a result of intramolecular photoelectron diffraction carry information on the dynamics of hydrogen migration in real space. Although visualization of this dynamics is more straightforward in the smaller systems, methanol and ethanol, one can still recognize the signature of that motion in propanol and isopropyl alcohol and assign a tentative path to it. A possible pathway for a corresponding experiment requires an angularly resolved detection of photoelectrons in coincidence with molecular fragment ions used to define a molecular frame of reference. Such studies have become, in principle, possible since the first XFELs with sufficiently high repetition rates have emerged. To further support our findings, we provide experimental evidence of H migration in ethanol-OD from ion-ion coincidence measurements performed with synchrotron radiation.
RESUMEN
We present a study on molecular-frame photoelectron angular distributions (MFPADs) of small molecules using circularly polarized synchrotron light. We find that the main forward-scattering peaks of the MFPADs are slightly tilted with respect to the molecular axis. This tilt angle is directly connected to the molecular bond length by a simple, universal formula. We apply the derived formula to several examples of MFPADs of C 1s and O 1s photoelectrons of CO, which have been measured experimentally or obtained by means of ab initio modeling. In addition, we discuss the influence of the back-scattering contribution that is superimposed over the analyzed forward-scattering peak in the case of homo-nuclear diatomic molecules such as N2.
RESUMEN
An open-loop control scheme of molecular fragmentation based on transient molecular alignment combined with single-photon ionization induced by a short-wavelength free electron laser (FEL) is demonstrated for the acetylene cation. Photoelectron spectra are recorded, complementing the ion yield measurements, to demonstrate that such control is the consequence of changes in the electronic response with molecular orientation relative to the ionizing field. We show that stable C2H2+ cations are mainly produced when the molecules are parallel or nearly parallel to the FEL polarization, while the hydrogen fragmentation channel (C2H2+ â C2H+ + H) predominates when the molecule is perpendicular to that direction, thus allowing one to distinguish between the two photochemical processes. The experimental findings are supported by state-of-the art theoretical calculations.
RESUMEN
The interaction of intense femtosecond x-ray pulses with molecules sensitively depends on the interplay between multiple photoabsorptions, Auger decay, charge rearrangement, and nuclear motion. Here, we report on a combined experimental and theoretical study of the ionization and fragmentation of iodomethane (CH_{3}I) by ultraintense (â¼10^{19} W/cm^{2}) x-ray pulses at 8.3 keV, demonstrating how these dynamics depend on the x-ray pulse energy and duration. We show that the timing of multiple ionization steps leading to a particular reaction product and, thus, the product's final kinetic energy, is determined by the pulse duration rather than the pulse energy or intensity. While the overall degree of ionization is mainly defined by the pulse energy, our measurement reveals that the yield of the fragments with the highest charge states is enhanced for short pulse durations, in contrast to earlier observations for atoms and small molecules in the soft x-ray domain. We attribute this effect to a decreased charge transfer efficiency at larger internuclear separations, which are reached during longer pulses.
RESUMEN
We report on a joint experimental and theoretical study of photoelectron circular dichroism (PECD) in methyloxirane. By detecting O 1s photoelectrons in coincidence with fragment ions, we deduce the molecule's orientation and photoelectron emission direction in the laboratory frame. Thereby, we retrieve a fourfold differential PECD clearly beyond 50%. This strong chiral asymmetry is reproduced by ab initio electronic structure calculations. Providing such a pronounced contrast makes PECD of fixed-in-space chiral molecules an even more sensitive tool for chiral recognition in the gas phase.
RESUMEN
Following the accident at Fukushima Daiichi nuclear power plant in 2011, a series of health literacy training workshops for local health workers was developed and implemented. This study aimed to analyse who among the intended audience gained the greatest benefit from the training. Nine health workers attended a workshop consisting of classroom training and a follow-up feedback assessment of materials they created in the workshop. The materials were assessed by a total of 131 intended readers. Using Sakai's tool, those items asking readers to rate the accessibility of written information were used to compare the materials before and after revision. The total score for Sakai's measure showed a significant improvement, and the elderly and those without regular doctor visits were more likely to notice improvements after revision. Such health literacy training could serve as a model programme to prevent inequity in access to health information in the face of a regional health crisis.
Asunto(s)
Accidente Nuclear de Fukushima , Alfabetización en Salud , Protección Radiológica , Anciano , Retroalimentación , Humanos , Japón , Plantas de Energía NuclearRESUMEN
α-RuCl3 is a major candidate for the realization of the Kitaev quantum spin liquid, but its zigzag antiferromagnetic order at low temperatures indicates deviations from the Kitaev model. We have quantified the spin Hamiltonian of α-RuCl3 by a resonant inelastic x-ray scattering study at the Ru L3 absorption edge. In the paramagnetic state, the quasi-elastic intensity of magnetic excitations has a broad maximum around the zone center without any local maxima at the zigzag magnetic Bragg wavevectors. This finding implies that the zigzag order is fragile and readily destabilized by competing ferromagnetic correlations. The classical ground state of the experimentally determined Hamiltonian is actually ferromagnetic. The zigzag state is stabilized by quantum fluctuations, leaving ferromagnetism - along with the Kitaev spin liquid - as energetically proximate metastable states. The three closely competing states and their collective excitations hold the key to the theoretical understanding of the unusual properties of α-RuCl3 in magnetic fields.
RESUMEN
AIM: To differentiate between infectious and non-infectious diseases occurring in immunocompromised patients without acquired immunodeficiency syndrome (AIDS) using high-resolution computed tomography (HRCT). MATERIALS AND METHODS: HRCT images of 555 patients with chest complications were reviewed retrospectively. Infectious diseases (n=341) included bacterial pneumonia (n=123), fungal infection (n=80), septic emboli (n=11), tuberculosis (n=15), pneumocystis pneumonia (n=101), and cytomegalovirus pneumonia (n=11), while non-infectious diseases (n=214) included drug toxicity (n=84), infiltration of underlying diseases (n=83), idiopathic pneumonia syndrome (n=34), diffuse alveolar haemorrhage (n=8), and pulmonary oedema (n=5). Lung parenchymal abnormalities were compared between the two groups using the χ2 test and multiple logistic regression analysis. RESULTS: The χ2 test results showed significant differences in many HRCT findings between the two groups. Multiple logistic regression analysis results indicated the presence of nodules with a halo and the absence of interlobular septal (ILS) thickening were the significant indicators that could differentiate infectious from non-infectious diseases. ILS thickening was generally less frequent among most infectious diseases and more frequent among most non-infectious diseases, with a good odds ratio (7.887, p<0.001). The sensitivity and accuracy for infectious diseases in the absence of ILS thickening were better (70% and 73%, respectively) than those of nodules with a halo (19% and 48%, respectively), while the specificity in the nodules with a halo was better (93%) than that of ILS thickening (78%). CONCLUSIONS: The presence of nodules with a halo or the absence of ILS thickening tends to suggest infectious disease. Specifically, ILS thickening seems to be a more reliable indicator.
Asunto(s)
Huésped Inmunocomprometido , Radiografía Torácica/métodos , Enfermedades Torácicas/diagnóstico por imagen , Tomografía Computarizada por Rayos X/métodos , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Preescolar , Enfermedades Transmisibles/diagnóstico por imagen , Diagnóstico Diferencial , Femenino , Humanos , Masculino , Persona de Mediana Edad , Enfermedades no Transmisibles , Estudios RetrospectivosRESUMEN
The Weyl semimetal (WSM), which hosts pairs of Weyl points and accompanying Berry curvature in momentum space near Fermi level, is expected to exhibit novel electromagnetic phenomena. Although the large optical/electronic responses such as nonlinear optical effects and intrinsic anomalous Hall effect (AHE) have recently been demonstrated indeed, the conclusive evidence for their topological origins has remained elusive. Here, we report the gigantic magneto-optical (MO) response arising from the topological electronic structure with intense Berry curvature in magnetic WSM Co3Sn2S2. The low-energy MO spectroscopy and the first-principles calculation reveal that the interband transitions on the nodal rings connected to the Weyl points show the resonance of the optical Hall conductivity and give rise to the giant intrinsic AHE in dc limit. The terahertz Faraday and infrared Kerr rotations are found to be remarkably enhanced by these resonances with topological electronic structures, demonstrating the novel low-energy optical response inherent to the magnetic WSM.
RESUMEN
We describe the clinical and histological characteristics of stromal-type nephroblastomas that developed in two hedgehogs (Atelerix albiventris). In case 1, the tumour was composed of a proliferation of anaplastic stromal cells with ductal structures resembling the epithelium of nephroblastoma. In case 2, spindle-shaped cells that were somewhat larger than nephroblasts were frequently seen surrounding the cell cluster, and there was proliferation of stromal cells with collagen fibres at the periphery. Immunohistochemically, the tumour cells labelled weakly to strongly for the nephroblast marker Wilms' tumour-1 and were positive for Ki67 with rates of 5% and 10% for cases 1 and 2, respectively. Based on the above, the diagnosis was of stromal-type nephroblastoma with anaplasia in case 1 and without anaplasia in case 2. Our findings suggest that stromal-type nephroblastomas arise in adult hedgehogs and are clinically benign, and that histological anaplasia does not affect the prognosis.
Asunto(s)
Erizos , Neoplasias Renales/veterinaria , Tumor de Wilms/veterinaria , Anaplasia , Animales , Biomarcadores de Tumor/metabolismo , Femenino , Inmunohistoquímica , Antígeno Ki-67/metabolismo , Riñón/patología , Neoplasias Renales/patología , Masculino , Proteínas WT1/metabolismo , Tumor de Wilms/patologíaRESUMEN
We introduce and present a theory of interferometric measurement of a normal Auger decay lifetime in molecules. Molecular Auger interferometry is based on the coherent phase control of Auger dynamics in a two-color (ω/2ω) laser field. We show that, in contrast to atoms, in oriented molecules of certain point groups the relative ω/2ω phase modulates the total ionization yield. A simple analytical formula is derived for the extraction of the lifetimes of Auger-active states from a molecular Auger interferogram, circumventing the need in either high-resolution or attosecond spectroscopy. We demonstrate the principle of the interferometric Auger lifetime measurement using inner-valence decay in CH_{3}F.
RESUMEN
This study investigated displacement of the tracheal tube caused by different methods of intubating stylet removal, using in-vitro experiments and mathematical analysis. In the first in-vitro experiment, we measured the distance travelled by the tube tip during stylet extraction. Then, we investigated the ideal technique for stylet extraction using mathematical analysis, which would cause minimal tube displacement. Then, using a training manikin, we measured the force applied to the vocal cords and stylet extraction force during tracheal intubation. When the stylet was extracted along a straight path towards the stylet end, the distance travelled by the tube tip significantly increased as the bending angle increased. Mathematical analysis revealed that the stylet should be diagonally extracted (in the sagittal plane) at an appropriate angle, rather than along a straight path towards the direction of the stylet end. In simulated tracheal intubation, extraction force and force applied to the vocal cords both significantly increased as the bending angle increased. Compared with the 'hockey stick'-shaped stylet, the arcuate-shaped stylet resulted in reduced force. Our results indicate the potential risk for vocal cord injury when using hockey stick-shaped stylets with large bending angles.
Asunto(s)
Intubación Intratraqueal/métodos , Maniquíes , Humanos , Intubación Intratraqueal/efectos adversos , Intubación Intratraqueal/instrumentación , MatemáticaRESUMEN
We describe a black-tailed prairie dog (Cynomys ludovicianus) with a benign biphasic nodular tumour that recurred as a malignant biphasic tumour at the same site 2 years after resection. Both tumours were biphasic with regard to the glandular epithelium and basal cells and contained little of the mucus, cartilage or fibrous tissue that characterize pleomorphic adenoma and carcinoma ex-pleomorphic adenoma. Both the first and second tumours exhibited histopathological features similar to those exhibited by human basal cell adenoma and adenocarcinoma, respectively. Both were resected and the animal was alive with no recurrence or metastasis at the time of writing, 9 months after the second surgery.
Asunto(s)
Adenocarcinoma/veterinaria , Adenoma/veterinaria , Recurrencia Local de Neoplasia/veterinaria , Enfermedades de los Roedores/patología , Neoplasias de las Glándulas Salivales/veterinaria , Animales , Masculino , SciuridaeRESUMEN
Ruthenium compounds serve as a platform for fundamental concepts such as spin-triplet superconductivity1, Kitaev spin liquids2-5 and solid-state analogues of the Higgs mode in particle physics6,7. However, basic questions about the electronic structure of ruthenates remain unanswered, because several key parameters (including Hund's coupling, spin-orbit coupling and exchange interactions) are comparable in magnitude and their interplay is poorly understood, partly due to difficulties in synthesizing large single crystals for spectroscopic experiments. Here we introduce a resonant inelastic X-ray scattering (RIXS)8,9 technique capable of probing collective modes in microcrystals of 4d electron materials. We observe spin waves and spin-state transitions in the honeycomb antiferromagnet SrRu2O6 (ref. 10) and use the extracted exchange interactions and measured magnon gap to explain its high Néel temperature11-16. We expect that the RIXS method presented here will enable momentum-resolved spectroscopy of a large class of 4d transition-metal compounds.
RESUMEN
SETTING AND OBJECTIVE: Several studies have found a significant association between tuberculosis (TB) and spatial factors. We wished to determine the effect of host-related factors and spatial factors associated with an increased risk of TB, and to assess spatial clustering. DESIGN: A hospital-based case-control study using medical records was conducted. A total of 103 age- and sex-matched TB patients (cases) and 299 patients without TB (controls) were recruited from January 2000 to December 2016 in a hospital in Nagata, Kobe, Japan. Logistic regression, kernel density estimation, Cross L function and a Poisson regression model were applied. RESULTS: The epidemiological factors associated with TB were being a health care worker (OR 10.1) and lower serum albumin level (OR 0.5). Spatial analyses revealed TB to be positively associated with population density (risk ratio [RR] 32.1), the proportion of single households (RR -1.85) and persons aged î¶65 years (RR 2.65) and one spatial clustering. CONCLUSION: Our findings could help in the identification of high TB risk individuals and districts.
Asunto(s)
Personal de Salud/estadística & datos numéricos , Densidad de Población , Análisis Espacial , Tuberculosis/epidemiología , Adolescente , Adulto , Factores de Edad , Anciano , Anciano de 80 o más Años , Estudios de Casos y Controles , Composición Familiar , Femenino , Humanos , Japón/epidemiología , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Albúmina Sérica/metabolismo , Adulto JovenRESUMEN
We examine instrumental and methodological capabilities for microscale (10-50 µg of C) radiocarbon analysis of individual compounds in the context of paleoclimate and paleoceanography applications, for which relatively high-precision measurements are required. An extensive suite of data for 14C-free and modern reference materials processed using different methods and acquired using an elemental-analyzer-accelerator-mass-spectrometry (EA-AMS) instrumental setup at ETH Zurich was compiled to assess the reproducibility of specific isolation procedures. In order to determine the precision, accuracy, and reproducibility of measurements on processed compounds, we explore the results of both reference materials and three classes of compounds (fatty acids, alkenones, and amino acids) extracted from sediment samples. We utilize a MATLAB code developed to systematically evaluate constant-contamination-model parameters, which in turn can be applied to measurements of unknown process samples. This approach is computationally reliable and can be used for any blank assessment of small-size radiocarbon samples. Our results show that a conservative lower estimate of the sample sizes required to produce relatively high-precision 14C data (i.e., with acceptable errors of <5% on final 14C ages) and high reproducibility in old samples (i.e., F14C ≈ 0.1) using current isolation methods are 50 and 30 µg of C for alkenones and fatty acids, respectively. Moreover, when the F14C is >0.5, a precision of 2% can be achieved for alkenone and fatty acid samples containing ≥15 and 10 µg of C, respectively.
RESUMEN
AIMS: This study was conducted to assess the presence and extent of differences in the gut microbiota of common bottlenose dolphins depending on rearing facilities. METHODS AND RESULTS: Faecal samples were collected from 16 common bottlenose dolphins at three aquaria in Japan. After extracting DNA from the faeces, the V3-V4 region of bacterial 16S rRNA was amplified and sequenced using Illumina MiSeq platform. The constituent phyla of the gut microbiota were similar among aquaria; however, the most dominant phylum differed depending on the facility, and the compositions of microbiota were remarkably varied at the family level among aquaria. The alpha diversity indices tended to differ among aquaria. Some bacterial families observed in terrestrial mammalian carnivores or carnivorous fish were detected, as well as several bacterial species suspected of being pathogenic in dolphins. CONCLUSION: Our findings indicate that captive environmental conditions including prey and housing types may contribute to differences in the gut microbiota of the dolphins. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study revealing the differences in gut microbiota of captive dolphins among facilities. Our findings will provide valuable information for improving the health management of dolphins.
Asunto(s)
Bacterias/aislamiento & purificación , Delfín Mular/microbiología , Microbioma Gastrointestinal , Animales , Bacterias/clasificación , Bacterias/genética , Delfín Mular/crecimiento & desarrollo , ADN Bacteriano/genética , Heces/microbiología , Hidrobiología , Japón , ARN Ribosómico 16S/genéticaRESUMEN
A mixture of CF_{4} and CO gases is used to study photoelectron recoil effects extending into the tender x-ray region. In CF_{4}, the vibrational envelope of the C 1s photoelectron spectrum becomes fully dominated by the recoil-induced excitations, revealing vibrational modes hidden from Franck-Condon excitations. In CO, using CF_{4} as an accurate energy calibrant, we determine the partitioning of the recoil-induced internal excitation energy between rotational and vibrational excitation. The observed rotational recoil energy is 2.88(28) times larger than the observed vibrational recoil energy, well in excess of the ratio of 2 predicted by the basic recoil model. The experiment is, however, in good agreement with the value of 2.68 if energy transfer via Coriolis coupling is included.
RESUMEN
Although the occurrence of cellulitis in lymphedema (LE) is believed to be an infection-related event, many findings in its clinical course seem to suggest that it is unlikely to be an infection. Therefore, we tried to clarify the specific features of cellulitis in LE. In-hospital courses of cellulitis obtained from medical charts were reviewed in the patients with leg LE (LE; 24 patients, 72admissions), chronic venous insufficiency (CVI; 28 patients, 29 admissions), and leg cellulitis secondary to wound infection without underlying disease (N; 42 patients, 42 admissions). The patients with LE complained of less local pain (peak numerical scale; LE: 1.4 ± 1.7, CVI: 4.1 ± 2.5, N: 3.2 ±2.0, p < 0.0001), showed an abnormally higher peak procalcitonin level (LE: 33.8 ± 34.8 (N = 7), CVI: 2.9 ± 5.8 (N = 8), N: 0.4 ± 0.6(N = 10), p < 0.05), and required fewer antibiotics (LE: 1.1 ± 0.3, CVI: 1.8 ± 0.9, N: 1.5 ± 0.9, p < 0.0001). These findings suggested that the occurrence of cellulitis in LE seems unlikely to be an infection-related type of cellulitis similar to that found in CVI.