Benedicta D. Arhatari
La Trobe University
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Featured researches published by Benedicta D. Arhatari.
Scientific Reports | 2013
Michael W.M. Jones; Grant van Riessen; Brian Abbey; Corey T. Putkunz; Mark D. Junker; Eugeniu Balaur; David J. Vine; Ian McNulty; Bo Chen; Benedicta D. Arhatari; Sarah Frankland; Keith A. Nugent; Leann Tilley; Andrew G. Peele
X-ray tomography can provide structural information of whole cells in close to their native state. Radiation-induced damage, however, imposes a practical limit to image resolution, and as such, a choice between damage, image contrast, and image resolution must be made. New coherent diffractive imaging techniques, such Fresnel Coherent Diffractive Imaging (FCDI), allows quantitative phase information with exceptional dose efficiency, high contrast, and nano-scale resolution. Here we present three-dimensional quantitative images of a whole eukaryotic cell by FCDI at a spatial resolution below 70 nm with sufficient phase contrast to distinguish major cellular components. From our data, we estimate that the minimum dose required for a similar resolution is close to that predicted by the Rose criterion, considerably below accepted estimates of the maximum dose a frozen-hydrated cell can tolerate. Based on the dose efficiency, contrast, and resolution achieved, we expect this technique will find immediate applications in tomographic cellular characterisation.
Review of Scientific Instruments | 2004
Benedicta D. Arhatari; Adrian P. Mancuso; Andrew G. Peele; Keith A. Nugent
We consider image formation for the phase-contrast radiography technique where the radiation source is extended and spatially incoherent. A model is developed for this imaging process which allows us to define an objective filtering criterion that can be applied to the recovery of quantitative phase images from data obtained at different propagation distances. We test our image model with experimental x-ray data. We then apply our filter to experimental neutron phase radiography data and demonstrate improved image quality.
Optics Express | 2008
Benedicta D. Arhatari; Kevin. Hannah; Eugeniu Balaur; Andrew G. Peele
We describe a quantitative phase imaging process using an x-ray laboratory-based source with an extremely broad bandwidth spectrum. The thickness of a homogeneous object can be retrieved by using separately spectrally weighted values for the attenuation coefficient and the decrement of the real part of the refractive index. This method is valid for a wide range of object types, including objects with an absorption edge in the used energy range. The accessibility of conventional x-ray laboratory sources makes this method very useful for quantitative phase retrieval of homogeneous objects. We demonstrate the application of this method for quantitative phase retrieval imaging in tomographic measurements.
Physics in Medicine and Biology | 2011
Benedicta D. Arhatari; David M.L. Cooper; C.D.L. Thomas; John G. Clement; Andrew G. Peele
By applying a phase-retrieval step before carrying out standard filtered back-projection reconstructions in tomographic imaging, we were able to resolve structures with small differences in density within a densely absorbing sample. This phase-retrieval tomography is particularly suited for the three-dimensional segmentation of secondary osteons (roughly cylindrical structures) which are superimposed upon an existing cortical bone structure through the process of turnover known as remodelling. The resulting images make possible the analysis of the secondary osteon structure and the relationship between an osteon and the surrounding tissue. Our observations have revealed many different and complex 3D structures of osteons that could not be studied using previous methods. This work was carried out using a laboratory-based x-ray source, which makes obtaining these sorts of images readily accessible.
Cell Death and Disease | 2012
Marina R. Carpinelli; Andrew K. Wise; Benedicta D. Arhatari; Phillipe Bouillet; Shehnaaz S.M. Manji; Michael G. Manning; Anne A. Cooray; Rachel A. Burt
In this paper we describe novel and specific roles for the apoptotic regulators Bcl2 and Bim in hearing and stapes development. Bcl2 is anti-apoptotic while Bim is pro-apoptotic. Characterization of the auditory systems of mice deficient for these molecules revealed that Bcl2−/− mice suffered severe hearing loss. This was conductive in nature and did not affect sensory cells of the inner ear, with cochlear hair cells and neurons present and functional. Bcl2−/− mice were found to have a malformed, often monocrural, porous stapes (the small stirrup-shaped bone of the middle ear), but a normally shaped malleus and incus. The deformed stapes was discontinuous with the incus and sometimes fused to the temporal bones. The defect was completely rescued in Bcl2−/−Bim−/− mice and partially rescued in Bcl2−/−Bim+/− mice, which displayed high-frequency hearing loss and thickening of the stapes anterior crus. The Bcl2−/− defect arose in utero before or during the cartilage stage of stapes development. These results implicate Bcl2 and Bim in regulating survival of second pharyngeal arch or neural crest cells that give rise to the stapes during embryonic development.
Review of Scientific Instruments | 2005
Benedicta D. Arhatari; Keith A. Nugent; Andrew G. Peele; John Thornton
An image model for phase contrast in projection radiography of complex objects is presented and tested experimentally. The model includes the wavelength distribution of the radiation. The model is used to optimize the contrast of a radiograph of a piece of aluminium containing a fine crack.
Cochlear Implants International | 2014
Graeme M. Clark; Jonathan C. M. Clark; Tina Cardamone; Maria Clarke; Prue Nielsen; Robert Jones; Benedicta D. Arhatari; N. Birbilis; Roger Curtain; Jin Xu; Sheryl Wagstaff; Peter Gibson; Stephen O'Leary; John B. Furness
Abstract Objective To analyse the temporal bones and implant of the first University of Melbournes (UOM) patient (MC-1) to receive the multi-channel cochlear prosthesis. Methods The left cochlea was implanted with the prototype multi-channel cochlear prosthesis on 1 August 1978, and the Cochlear versions CI-22 and CI-24 on 22 June 1983 and 10 November 1998, respectively. MC-1 died in 2007. Results Plain X-rays of the temporal bones showed that after the CI-22 had been explanted seven electrode bands remained in situ. Micro-CT scans also revealed a partially united fracture transecting the left implanted and right control cochleae. Histology indicated a total loss of the organ of Corti on both sides, and a tear of the left basilar membrane. In addition, there was a dense fibrous capsule with heterotopic bone surrounding one proximal band of the CI-22 array that restricted its removal. This pathology was associated with dark particulate material within macrophages, probably due to the release of platinum from the electrode bands. Scanning electron microscopy (SEM) showed possible corrosion of platinum and surface roughening. Three-dimensional reconstruction of the cochlear histology demonstrated the position of the electrode tracts (C1-22 and CI-24) in relation to the spiral ganglion, which showed 85–90% loss of ganglion cells. Discussion and conclusions This study confirms our first histopathological findings that our first free-fitting banded electrode array produced moderate trauma to the cochlea when inserted around the scala tympani of the basal turn. The difficulty in extraction was most likely due to one band being surrounded by an unusually large amount of fibrous tissue and bone, with an electrode band caught due to surface irregularities. Some surface corrosion and a small degree of platinum deposition in the tissue may also help explain the outcome for this long-term cochlear implantation.
Journal of Applied Physics | 2010
Benedicta D. Arhatari; Will P. Gates; Nicky Eshtiaghi; A. G. Peele
We describe the use of single-plane phase retrieval tomography using a laboratory-based x-ray source, under conditions where the retrieval is not formally valid, to present images of the internal structure of an Aerosil granule and a hydrated bentonite gel. The technique provides phase images for samples that interact weakly with the x-ray beam. As the method is less affected by noise than an alternative two-plane phase retrieval method that is otherwise formally valid, object structure can be observed that would not otherwise be seen. We demonstrate our results for phase imaging in tomographic measurements.
Review of Scientific Instruments | 2007
Benedicta D. Arhatari; F. De Carlo; Andrew G. Peele
We examine a direct filtered back projection approach that is suitable for the reconstruction of weakly absorbing homogeneous phase objects. Like recent similar approaches this method needs only one intensity image in each projection without the requirement for an intermediate step of phase retrieval. We tested the method using simulation and experimental results. Simulation results show good quantitative reconstruction which includes the correct refractive index value and distribution of the sample. However, experimental result still indicates the presence of artifacts.
Ultramicroscopy | 2008
Keith A. Nugent; Benedicta D. Arhatari; Andrew G. Peele
Optical coherence theory is used to describe image formation in a telecentric optical system. By assuming a weakly interacting object and by considering points that are not too far from the optical axis, an optical transfer function description is obtained for imaging both the phase and the amplitude components of the object. A dimensionless coordinate system is identified to allow the transfer functions to be expressed independently of the details of the imaging system. Phase-contrast imaging is found to have an essentially coherent behaviour when the coherence length is a factor of 15 larger than the system resolution, and that the coherent region of the illumination therefore does not need to encompass the object.