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1.
J Synchrotron Radiat ; 28(Pt 1): 283-291, 2021 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-33399579

RESUMEN

Analyser-based phase-contrast imaging (ABPCI) is a highly sensitive phase-contrast imaging method that produces high-contrast images of weakly absorbing materials. However, it is only sensitive to phase gradient components lying in the diffraction plane of the analyser crystal [i.e. in one dimension (1-D)]. In order to accurately account for and measure phase effects produced by the wavefield-sample interaction, ABPCI and other 1-D phase-sensitive methods must achieve 2-D phase gradient sensitivity. An inclined geometry method was applied to a Laue geometry setup for X-ray ABPCI through rotation of the detector and object about the optical axis. This allowed this traditionally 1-D phase-sensitive phase-contrast method to possess 2-D phase gradient sensitivity. Tomographic datasets were acquired over 360° of a multi-material phantom with the detector and sample tilted by 8°. The real and imaginary parts of the refractive index were reconstructed for the phantom.


Asunto(s)
Interpretación de Imagen Radiográfica Asistida por Computador/métodos , Tomografía Computarizada por Rayos X/métodos , Algoritmos , Óptica y Fotónica , Fantasmas de Imagen , Sincrotrones
2.
J Synchrotron Radiat ; 20(Pt 2): 219-25, 2013 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-23412477

RESUMEN

A Si(111) winged crystal has been designed to minimize anticlastic bending and improve sagittal focusing efficiency. The crystal was thin with wide stiffening wings. The length-to-width ratio of the crystal was optimized by finite element analysis, and the optimal value was larger than the `golden value'. The analysis showed that the slope error owing to anticlastic bending is less than the Darwin width. The X-rays were focused two-dimensionally using the crystal and a tangentially bent mirror. The observed profiles of the focal spot agreed well with the results of a ray-tracing calculation in the energy range from 8 to 17.5 keV. X-ray diffraction measurements with a high signal-to-noise ratio using this focusing system were demonstrated for a small protein crystal.


Asunto(s)
Muramidasa/química , Difracción de Rayos X/métodos , Animales , Cristalización/instrumentación , Diseño de Equipo , Sincrotrones
3.
J Synchrotron Radiat ; 18(Pt 2): 217-23, 2011 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-21335908

RESUMEN

X-ray imaging detectors with an identical phosphor and a CCD chip but employing lens- and fiber-coupling between them have been compared. These are designed for X-ray imaging experiments, especially computed tomography, at the medium-length beamline at the SPring-8 synchrotron radiation facility. It was found that the transmittance of light to the CCD is about four times higher in the fiber-coupled detector. The uniformity of response in the lens-coupled detector has a global shading of up to 40%, while pixel-to-pixel variation owing to a chicken-wire pattern was dominant in the fiber-coupled detector. Apart from the higher transmittance, the fiber-coupled detector has a few characteristics that require attention when it is used for computed tomography, which are browning of the fiber, discontinuity in the image, image distortion, and dark spots in the chicken-wire pattern. Thus, it is most suitable for high-speed tomography of samples that tend to deform, for example biological and soft materials.


Asunto(s)
Tomografía Computarizada por Rayos X/métodos , Microtomografía por Rayos X/métodos , Diseño de Equipo , Lentes , Tomografía Computarizada por Rayos X/instrumentación , Microtomografía por Rayos X/instrumentación
4.
Opt Express ; 18(7): 6423-36, 2010 Mar 29.
Artículo en Inglés | MEDLINE | ID: mdl-20389666

RESUMEN

A method of tomographic phase retrieval is developed for multi-material objects whose components each has a distinct complex refractive index. The phase-retrieval algorithm, based on the Transport-of-Intensity equation, utilizes propagation-based X-ray phase contrast images acquired at a single defocus distance for each tomographic projection. The method requires a priori knowledge of the complex refractive index for each material present in the sample, together with the total projected thickness of the object at each orientation. The requirement of only a single defocus distance per projection simplifies the experimental setup and imposes no additional dose compared to conventional tomography. The algorithm was implemented using phase contrast data acquired at the SPring-8 Synchrotron facility in Japan. The three-dimensional (3D) complex refractive index distribution of a multi-material test object was quantitatively reconstructed using a single X-ray phase-contrast image per projection. The technique is robust in the presence of noise, compared to conventional absorption based tomography.


Asunto(s)
Imagenología Tridimensional/métodos , Microscopía de Contraste de Fase/instrumentación , Tomografía Computarizada por Rayos X/métodos , Rayos X , Algoritmos , Diseño de Equipo , Microscopía de Contraste de Fase/métodos , Óptica y Fotónica , Refractometría , Sincrotrones
5.
Opt Express ; 18(13): 13478-91, 2010 Jun 21.
Artículo en Inglés | MEDLINE | ID: mdl-20588478

RESUMEN

A rotating random-phase-screen diffuser is sometimes employed on synchrotron x-ray imaging beamlines to ameliorate field-of-view inhomogeneities due to electron-beam instabilities and beamline optics phase artifacts. The ideal result is a broader, more uniformly illuminated beam intensity for cleaner coherent x-ray images. The spinning diffuser may be modeled as an ensemble of transversely random thin phase screens, with the resulting set of intensity maps over the detector plane being incoherently averaged over the ensemble. Whilst the coherence width associated with the source is unaffected by the diffuser, the magnitude of the complex degree of second-order coherence may be significantly reduced [K. S. Morgan, S. C. Irvine, Y. Suzuki, K. Uesugi, A. Takeuchi, D. M. Paganin, and K. K. W. Siu, Opt. Commun. 283, 216 (2010)]. Through use of a computational model and experimental data obtained on x-ray beamline BL20XU at SPring-8, Japan, we investigate the effects of such a diffuser on the quality of Fresnel diffraction fringes in propagation-based x-ray phase contrast imaging. We show that careful choice of diffuser characteristics such as thickness and fiber size, together with appropriate placement of the diffuser, can result in the ideal scenario of negligible reduction in fringe contrast whilst the desired diffusing properties are retained.


Asunto(s)
Simulación por Computador , Tejido Conectivo/diagnóstico por imagen , Modelos Biológicos , Radiografía/instrumentación , Radiografía/métodos , Sincrotrones , Diseño de Equipo , Análisis de Fourier , Flujo Sanguíneo Regional
6.
Phys Med Biol ; 53(21): 6065-77, 2008 Nov 07.
Artículo en Inglés | MEDLINE | ID: mdl-18843172

RESUMEN

Phase contrast x-ray imaging can provide detailed images of lung morphology with sufficient spatial resolution to observe the terminal airways (alveoli). We demonstrate that quantitative functional and anatomical imaging of lung ventilation can be achieved in vivo using two-dimensional phase contrast x-ray images with high contrast and spatial resolution (<100 microm) in near real time. Changes in lung air volume as small as 25 microL were calculated from the images of term and preterm rabbit pup lungs (n = 28) using a single-image phase retrieval algorithm. Comparisons with plethysmography and computed tomography showed that the technique provided an accurate and robust method of measuring total lung air volumes. Furthermore, regional ventilation was measured by partitioning the phase contrast images, which revealed differences in aeration for different ventilation strategies.


Asunto(s)
Mediciones del Volumen Pulmonar/métodos , Pulmón/fisiología , Animales , Pletismografía , Conejos , Radiografía , Reproducibilidad de los Resultados , Respiración , Rayos X
7.
Bone ; 41(2): 239-46, 2007 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-17544983

RESUMEN

The canal network in cortical bone is an indispensable basis of bone vascularity, and its structure changes according to bone growth. Using monochromatic synchrotron radiation microCT (SRmicroCT), we evaluated the structural change of the canal network in growing rat tibiae and the response of this network to disuse. Tibiae were harvested from both hindlimbs of 9- and 14-week-old male Wistar rats subjected to unilateral sciatic neurectomy (SN) at 6 weeks of age (W9, n=8; W14, n=8) and from intact hindlimbs of 6-week-old rats (W6, n=8). Images of distal diaphyseal segments were reconstructed by SRmicroCT with a voxel size of 5.83 mum and then translated into local mineral densities using a calibrated relation between linear absorption coefficients and the concentration of K(2)HPO(4) solution. The canal network was segmented by simple thresholding at a bone mineral density of 0.82 g.cm(-3) and its structural properties were determined. In intact hindlimbs, the canal network showed a biphasic change with growth, as represented by increases followed by decreases in canal volume fraction (Ca.vol.f), the density of canals running longitudinally (Ca.num.d), and the density of canal connections (Ca.con.d): Ca.vol.f=2.2, 3.1, and 1.8%, Ca.num.d=77, 98, and 70 mm(-2), and Ca.con.d=18, 41, and 21 mm(-3) in W6, W9, and W14, respectively. In SN hindlimbs, bone growth deceleration was accompanied by a 16% smaller Ca.vol.f and a 22% smaller Ca.con.d in W9 and a 27% smaller Ca.vol.f, a 12% smaller Ca.num.d, and a 39% smaller Ca.con.d in W14 than those in intact hindlimbs. Furthermore, the canal branching structure became more treelike in SN hindlimbs. The effect of SN on the canal network appeared mainly in the periosteal sector of the anteriolateral cortex in W9 and spread throughout the cortex in W14. These findings will lead to a better understanding of microcirculation in cortical bone growth.


Asunto(s)
Desarrollo Óseo/fisiología , Resorción Ósea , Tibia , Animales , Masculino , Ratas , Ratas Wistar , Sincrotrones , Tibia/anatomía & histología , Tibia/fisiología , Tomografía Computarizada por Rayos X/métodos
8.
Sci Rep ; 7(1): 16755, 2017 12 01.
Artículo en Inglés | MEDLINE | ID: mdl-29196692

RESUMEN

Decompression times reported in previous studies suggest that thoroughly brittle fragmentation is unlikely in actual explosive volcanic eruptions. What occurs in practice is brittle-like fragmentation, which is defined as the solid-like fracture of a material whose bulk rheological properties are close to those of a fluid. Through laboratory experiments and numerical simulation, the link between the inhomogeneous structure of bubbles and the development of cracks that may lead to brittle-like fragmentation was clearly demonstrated here. A rapid decompression test was conducted to simulate the fragmentation of a specimen whose pore morphology was revealed by X-ray microtomography. The dynamic response during decompression was observed by high-speed photography. Large variation was observed in the responses of the specimens even among specimens with equal bulk rheological properties. The stress fields of the specimens under decompression computed by finite element analysis shows that the presence of satellite bubbles beneath a large bubble induced the stress concentration. On the basis of the obtained results, a new mechanism for brittle-like fragmentation is proposed. In the proposed scenario, the second nucleation of bubbles near the fragmentation surface is an essential process for the advancement of fragmentation in an upward magma flow in a volcanic conduit.

9.
Med Phys ; 32(9): 2787-92, 2005 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-16266092

RESUMEN

In order to evaluate the effectiveness of edge enhancement by refraction in computed tomography, images of a cross section of a euthanized mouse thorax were recorded at low (20 keV) and high (72 keV) x-ray energies at a spatial resolution of about 40 microm. Compared with the images obtained with the detector at 30 cm from an object, when the object was located at 113 cm from the detector, the contrast between tissues and air was improved at both energies. The improvement was more pronounced at 72 keV where the absorption contrast was weaker. This effect was due to refraction at the surfaces of alveolar membranes and small airways which creates areas with apparently high and low linear attenuation coefficients within tissues. The edge enhancement by refraction was also effective in images of a euthanized rabbit thorax at x-ray energies of 40 and 70 keV at a spatial resolution of about 0.15 mm. These results raise the possibility that the refraction contrast may be utilized to obtain a high-resolution tomographic image of human lung and bone with low dose.


Asunto(s)
Pulmón/diagnóstico por imagen , Intensificación de Imagen Radiográfica , Tomografía Computarizada por Rayos X , Animales , Ratones , Alveolos Pulmonares/diagnóstico por imagen , Conejos , Dispersión de Radiación
10.
Phys Med Biol ; 50(21): 5031-40, 2005 Nov 07.
Artículo en Inglés | MEDLINE | ID: mdl-16237239

RESUMEN

High quality real-time imaging of lungs in vivo presents considerable challenges. We demonstrate here that phase contrast x-ray imaging is capable of dynamically imaging the lungs. It retains many of the advantages of simple x-ray imaging, whilst also being able to map weakly absorbing soft tissues based on refractive index differences. Preliminary results reported herein show that this novel imaging technique can identify and locate airway liquid and allows lung aeration in newborn rabbit pups to be dynamically visualized.


Asunto(s)
Pulmón/patología , Radiografía Torácica/métodos , Animales , Animales Recién Nacidos , Humanos , Conejos , Intensificación de Imagen Radiográfica , Magnificación Radiográfica , Respiración , Factores de Tiempo , Rayos X
11.
Br J Radiol ; 78(935): 1018-27, 2005 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-16249603

RESUMEN

The significant degree of X-ray phase contrast created by air-tissue interfaces, coupled with the poor radiographic contrast of conventional chest radiographs, makes the inflated lung an ideal candidate for investigating the potential diagnostic improvement afforded by phase contrast X-ray imaging. In small animals these methods highlight the lung airways and lobe boundaries and reveal the lung tissue as a speckled intensity pattern not seen in other soft tissues. We have compared analyser-based and propagation-based phase contrast imaging modalities, together with conventional radiographic imaging, to ascertain which technique shows the greatest image enhancement for various lung sizes. The conventional radiographic image of a mouse was obtained on a Siemens Nova 3000 mammography system, whilst phase contrast images of mice and rabbit chests were acquired at the medical imaging beamline (20B2) at the SPring-8 synchrotron radiation research facility in Japan. For mice aged 1 day, 1 week and 1 month old it was determined that analyser-based imaging showed the greatest overall image contrast, however, for an adult rabbit both techniques yielded excellent contrast. The success of these methods in creating high quality images for rabbit lungs raises the possibility of improving human lung imaging using phase contrast techniques.


Asunto(s)
Pulmón/diagnóstico por imagen , Intensificación de Imagen Radiográfica/métodos , Animales , Femenino , Mamografía/instrumentación , Ratones , Conejos , Interpretación de Imagen Radiográfica Asistida por Computador , Especificidad de la Especie
12.
Rev Sci Instrum ; 86(7): 073701, 2015 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-26233390

RESUMEN

Analyses of nuclear emulsion detectors that can detect and identify charged particles or radiation as tracks have typically utilized optical microscope systems because the targets have lengths from several µm to more than 1000 µm. For recent new nuclear emulsion detectors that can detect tracks of submicron length or less, the current readout systems are insufficient due to their poor resolution. In this study, we developed a new system and method using an optical microscope system for rough candidate selection and the hard X-ray microscope system at SPring-8 for high-precision analysis with a resolution of better than 70 nm resolution. Furthermore, we demonstrated the analysis of submicron-length tracks with a matching efficiency of more than 99% and position accuracy of better than 5 µm. This system is now running semi-automatically.

13.
Phys Med Biol ; 49(18): 4335-48, 2004 Sep 21.
Artículo en Inglés | MEDLINE | ID: mdl-15509069

RESUMEN

Phase contrast x-ray imaging of small animal lungs reveals a speckled intensity pattern not seen in other tissues, making the lungs highly visible in comparison to other organs. Although bearing a superficial resemblance to alveoli, the cause of this speckle has not been established. With a view to determining the mechanism for the formation of speckle, this paper details the results of propagation-based phase contrast experiments performed on mice lungs, together with packed glass microspheres used to emulate lung tissue. These experimental studies are compared to numerical simulations, based on wave propagation techniques. We find that speckle arises from focusing effects, with multiple alveoli acting as aberrated compound refractive lenses. Both experiments and modelling suggest that this speckle-formation phenomenon may lead to better screening methods for human lungs than conventional radiography.


Asunto(s)
Pulmón/diagnóstico por imagen , Modelos Biológicos , Intensificación de Imagen Radiográfica/métodos , Interpretación de Imagen Radiográfica Asistida por Computador/métodos , Refractometría/métodos , Difracción de Rayos X/métodos , Algoritmos , Animales , Simulación por Computador , Masculino , Ratones , Fantasmas de Imagen , Conejos , Refractometría/instrumentación , Refractometría/veterinaria , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Difracción de Rayos X/instrumentación , Difracción de Rayos X/veterinaria
14.
J Pharm Sci ; 76(9): 695-8, 1987 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-11002804

RESUMEN

Nasal absorption of secretin in rats was enhanced in an acid solution, and the maximum absorption was observed at a sodium chloride solution molarity of 0.462. In order to examine reasons for the variation of absorbability caused by the change of pH and osmolarity in secretin preparations, both a pretreatment study, in which the nasal mucosa was treated with placebo prior to the administration of a secretin preparation, and a histological study were conducted in rats. The nasal absorption of secretin was determined by measuring the increased secretin of pancreatic juice. Similar profiles of nasal absorption, both after intranasal administration of secretin preparations and as a result of pretreatment effects, were obtained in studies of the effects of pH and osmolarity. However, in the pH-effect study, the absorption with the use of active preparations was observed to be significantly larger than that with the pretreatment effect below a pH of 4.79, and significantly smaller than that with the pretreatment effect at a pH of 7 to 8. The results of histological studies revealed structural changes of the epithelial cells of the nasal mucosa at pH 2.94, and shrinkage of epithelial cells was observed at a sodium chloride solution molarity of 0.462.


Asunto(s)
Mucosa Nasal/metabolismo , Secretina/farmacocinética , Absorción , Animales , Concentración de Iones de Hidrógeno , Masculino , Concentración Osmolar , Ratas , Ratas Sprague-Dawley
15.
Talanta ; 24(6): 391-3, 1977 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-18962107

RESUMEN

A new spectrophotometric method for the determination of gallium with Pontachrome Azure Blue B and cetyltrimethylammonium chloride is described. The sensitivity of the colour reaction between gallium and Pontachrome Azure Blue B is greatly increased in the presence of cetyltrimethylammonium chloride. The gallium complex has maximal absorbance at 680 nm and pH 6.0-6.6. Beer's law is obeyed over the range 0.08-0.6 ppm of gallium; the molar absorptivity is 1.39 x 10(5) 1.mole(-1). cm(-1) and sensitivity 4.9 x 10(-4) mu/cm(2). The mole ratio of the complex, the formation constant and effect of interfering ions are described.

16.
Talanta ; 31(12): 1112-4, 1984 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-18963733

RESUMEN

Trace iron(II) is determined spectrophotometrically after adsorption of its ternary complex with 3-(4-phenyl-2-pyridyl)-5,6-diphenyl-1,2,4-triazine and tetraphenylborate on microcrystalline naphthalene at pH 5.1-7.4. The absorption maximum is at 567 nm; the molar absorptivity is 2.9 x 10(4)lmole(-1)cm(-1).

17.
J Biosci Bioeng ; 88(1): 85-91, 1999.
Artículo en Inglés | MEDLINE | ID: mdl-16232579

RESUMEN

For enhancing the survival of genetically engineered microorganisms (GEMs) in activated sludge processes, the use of a floc-forming bacterium as the host for a recombinant plasmid was proposed. The floc-forming and phenol-degrading GEM Sphingomonas paucimobilis 551 (pS10-45) was cultured to demonstrate this proposal. Although the maximum growth rate of the host strain S. paucimobilis 551 was low and the recombinant plasmid pS10-45 was unstable in the host, the resultant GEM S. paucimobilis 551 (pS10-45) was difficult to wash out together with the effluent, and it maintained population 3-4 times higher than the non-floc-forming GEM Escherichia coli HB101 (pS10-45) in a model activated sludge process operated in a sequencing batch mode. In the long run, the GEM-inoculated activated sludge process showed better phenol removal ability by the recombinant plasmid and better sludge settlement by the host strain.

18.
Adv Exp Med Biol ; 467: 419-23, 1999.
Artículo en Inglés | MEDLINE | ID: mdl-10721084

RESUMEN

Tryptophan administration aggravates experimental mouse liver injury caused by carbon tetrachloride when 3-hydroxyanthranilic acid concentration elevates in serum. Tryptophan metabolism is changed by macrophages in injured liver. 3-Hydroxyanthranilic acid may be oxidized to cinnabarinic acid by injured mitochondria in the liver aggravating the state of injured liver. Mitochondria prepared from the liver 24 hr after CCl4 treatment have lost their ability of respiratory control. In consequence, 3-hydroxyanthranilic acid is oxidized to cinnabarinic acid by incubation with these mitochondria, whereas 3-hydroxykynurenine is not. Thus, formed cinnabarinic acid is able to inhibit completely the mitochondrial respiratory control at concentration of 10 microM.


Asunto(s)
Ácido 3-Hidroxiantranílico/farmacocinética , Intoxicación por Tetracloruro de Carbono/metabolismo , Mitocondrias Hepáticas/metabolismo , Oxazinas/farmacocinética , Pigmentos Biológicos , Xantenos , Aminoácidos/farmacocinética , Animales , Tetracloruro de Carbono/toxicidad , Quinurenina/sangre , Hígado/efectos de los fármacos , Hígado/patología , Ratones , Ratones Endogámicos , Mitocondrias Hepáticas/efectos de los fármacos , Mitocondrias Hepáticas/patología , Oxazinas/farmacología , Oxidación-Reducción , Consumo de Oxígeno/efectos de los fármacos , Transaminasas/sangre
19.
Intern Med ; 39(10): 820-5, 2000 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-11030207

RESUMEN

A malignant pheochromocytoma is described in a 71-year-old man. Osseous metastases became manifest 12 years after successful removal of the primary tumor which originated in paraganglionic tissue near the right adrenal gland. Although the patient had no symptoms of catecholamine excess initially, hypertension, tachycardia and excessive sweating appeared several months before his death, concomitantly with a sharp increase in noradrenaline secretion due to an accelerated growth of metastatic tumors. Since there is no histologic criterion of malignancy in this neoplasm, it would be prudent to consider every case of pheochromocytoma as potentially malignant and to follow-up carefully for a long time after removal of the primary tumor.


Asunto(s)
Neoplasias de las Glándulas Suprarrenales/patología , Neoplasias Óseas/secundario , Catecolaminas/sangre , Feocromocitoma/secundario , Neoplasias de las Glándulas Suprarrenales/sangre , Neoplasias de las Glándulas Suprarrenales/diagnóstico por imagen , Anciano , Neoplasias Óseas/sangre , Neoplasias Óseas/diagnóstico por imagen , Dopamina/sangre , Epinefrina/sangre , Resultado Fatal , Humanos , Hipertensión/complicaciones , Imagen por Resonancia Magnética , Masculino , Norepinefrina/sangre , Feocromocitoma/sangre , Feocromocitoma/diagnóstico por imagen , Cintigrafía , Sudoración Gustativa/complicaciones , Taquicardia/complicaciones
20.
J Laryngol Otol ; 104(4): 322-5, 1990 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-2196315

RESUMEN

The complication rate after emergency tracheostomy is two to five times greater than after elective procedures. One of the main causes of the high risk of complications in emergency tracheostomy appears to be the amount of time required to open the trachea. Therefore, simple and fast procedures are mandatory. We have developed a new procedure as follows: A horizontal skin incision is performed. Strap muscles are dissected and retracted laterally. A transverse cut between tracheal rings below the thyroid isthmus is performed up to membranous portion of the trachea. The cut ends of the trachea remain open naturally because of the elasticity of the trachea. Skin and tracheal cut-ends are then joined by interrupted sutures. We have used this procedure during the past three years and have not experienced any major complications. This demonstrates the clear advantage and the more physiological nature of the procedure over various other incisions of the tracheal wall.


Asunto(s)
Traqueostomía/métodos , Adulto , Anciano , Urgencias Médicas , Humanos , Masculino , Persona de Mediana Edad , Técnicas de Sutura , Factores de Tiempo , Tráquea/cirugía
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