306 research outputs found

    Analysis of corpus callosum size depending on age and sex

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    Background: The aim of the study was to analyse changes in the size of the corpus callosum (CC) depending on age and sex and to establish the reference values of the morphometric indices of the CC in the Polish population.  Materials and methods: The results of magnetic resonance studies of 1108 patients performed in the years 2010–2014 were analysed. Two independent radiologists evaluated cerebral images to exclude deviations from normal state. In patients divided according to sex and to 10 age groups, measurements of CC and brain dimensions were made and morphometric indices were calculated.  Results: The results of measurements related to the following parameters: lengths of longitudinal cross-section of CC (CD), CC thickness in the narrowest place — isthmus (EF), the largest linear dimension of the brain from the frontal pole to the occipital pole (AB), the longitudinal cross-section area of the CC (A1) and cerebral cross-section area (A2) as well as CD/AB and A1/A2 ratios are summarised in 7 figures and 3 tables.  Conclusions: It was demonstrated, that in all age groups there are statistically significant differences in the values of the analysed parameters and ratios of CC size. It was indicated, that there are no statistically significant differences between men and women in the CD, EF, and A1 parameters related to CC size, and the profiles of variations of these parameters are very similar. It was proved that the- re are statistical differences between women and men in parameters/indicators concerning of the brain size.

    Comparing the effect of CTG+STan with CTG alone on emergency Cesarean section rate : STan Australian Randomized controlled Trial (START)

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    The authors would like to thank the women and their babies for participating. We would like to thank all the staff at the WCH, in particular Priya Umampathysivam, Denise Cheetham and Cecilia Heitmann for their assistance in recruitment of participants for START. We would also like to thank the members of the DSMC, Diogo Ayres-de-Campos, Scott Morris and Katherine Lee, for their oversight of START and the Clinical Information Service (CIS) team at the WCH for the comparative hospital dataPeer reviewedPublisher PD

    In vivo cell tracking with 52Mn PET: Targetry, Separation, and Applications

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    Introduction 52Mn (t½ =5.59 d, β+ = 29.6%, Eβmax = 0.58 MeV) has great potential as a long lived PET isotope for use in cell tracking studies, observation of immunologic response to disease states, or as an alternative to manganese-based MRI contrast agents. Its favorable max positron energy leads to superb imaging resolution, comparable to that of 18F.[1] Manganese is naturally taken up by cells via a multitude of pathways including the divalent metal transporter (DMT1), ZIP8, transferrin receptors (TfR), store-operated Ca2+ channels (SOC-Ca2+), and ionotropic glutamate receptor Ca2+ channels (GluR).[2] These natural transport mechanisms make 52Mn an attractive isotope for applications necessitating non-perturbative cell uptake. In particular, cell tracking is critical to the development and translation of stem cell therapies in regenerative medicine. Alternative-ly, 52Mn could be used in immunotherapy techniques such as adoptive cellular therapy (ACT) to evaluate the ability of external immune cells to reach their intended target. Material and Methods 52Mn was produced by natCr(p,x)52Mn using 16 MeV protons. The average thick target production yield was 0.23 mCi/µA-h with less than 0.25% co-production of 54Mn. Small amounts of 51Cr were observed in the target, but were absent from the radiochemically separated product. Target construction consisted of a water jet cooled chromium disc (3/4” diameter, 0.4” thick). Targets were purchased from Kamis Inc, and are 99.95% pure. Targets withstood beam currents of 30 µA with no visible aberration. Chromium targets were etched by concentrated HCl following bombardment. Mn2+ ions were extracted from 9M HCl to 0.8M trioctylamine in cyclohexane leaving the bulk chromium in the aqueous phase. After isolating the organic phase, 0.001M NH4OH was used to back-extract the Mn2+ ions to aqueous phase. This purification cycle was conducted a total of three times for each 52Mn production. Results and Conclusion For a starting bulk chromium mass of 456 ± 1 mg, a post-separation chromium mass of 5.35 ± 0.04 ng was measured by microwave plasma atomic emission spectrometry (MP-AES). This mass reduction corresponds to an average separation factor of 440 for a single purification cycle. Each purification cycle had a 52Mn recovery efficiency of 73 ± 7 % (n = 6), resulting in an overall separation efficiency of approximately 35 %. These efficiencies and separation factors agree reasonably well with the work conducted by Lahiri et. al.[3] Prior to use, the product was passed through a C-18 Sep-Pak to remove any residual organic phase. After four target irradiations and etchings, some pitting became noticeable on the target face. These have not yet compromised the o-ring seal with the target deplater, but it is possible that target replacement after every 6–9 52Mn productions will be necessary moving forward. Following the successful separation of 52Mn from chromium, in vitro experiments were conducted to demonstrate the uptake of 52Mn by human stem cells and mouse tumor cells. A linear uptake response was observed as a function of the amount of activity exposed to the cells for both cell models. These experiments have shown great promise for 52Mn as a long-lived PET isotope in cell tracking studies. Details will be presented

    The theory of pulsar winds and nebulae

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    We review current theoretical ideas on pulsar winds and their surrounding nebulae. Relativistic MHD models of the wind of the aligned rotator, and of the striped wind, together with models of magnetic dissipation are discussed. It is shown that the observational signature of this dissipation is likely to be point-like, rather than extended, and that pulsed emission may be produced. The possible pulse shapes and polarisation properties are described. Particle acceleration at the termination shock of the wind is discussed, and it is argued that two distinct mechanisms must be operating, with the first-order Fermi mechanism producing the high-energy electrons (above 1 TeV) and either magnetic annihilation or resonant absorption of ion cyclotron waves responsible for the 100 MeV to 1 TeV electrons. Finally, MHD models of the morphology of the nebula are discussed and compared with observation.Comment: 33 pages, to appear in Springer Lecture Notes on "Neutron stars and pulsars, 40 years after the discovery", ed W.Becke

    Scalar and Tensor Inhomogeneities from Dimensional Decoupling

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    We discuss some perturbative techniques suitable for the gauge-invariant treatment of the scalar and tensor inhomogeneities of an anisotropic and homogeneous background geometry whose spatial section naturally decomposes into the direct product of two maximally symmetric Eucledian manifolds, describing a general situation of dimensional decoupling in which dd external dimensions evolve (in conformal time) with scale factor a(η)a(\eta) and nn internal dimensions evolve with scale factor b(η)b(\eta). We analyze the growing mode problem which typically arises in contracting backgrounds and we focus our attention on the situation where the amplitude of the fluctuations not only depends on the external space-time but also on the internal spatial coordinates. In order to illustrate the possible relevance of this analysis we compute the gravity waves spectrum produced in some highly simplified model of cosmological evolution and we find that the spectral amplitude, whose magnitude can be constrained by the usual bounds applied to the stochastic gravity waves backgrounds, depends on the curvature scale at which the compactification occurs and also on the typical frequency of the internal excitations.Comment: 31 pages, Latex, DAMTP 96-92, UCM 96-04, to appear in Phys. Rev. D 55 (1997

    First steps towards a fast-neutron therapy planning program

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    <p>Abstract</p> <p>Background</p> <p>The Monte Carlo code GEANT4 was used to implement first steps towards a treatment planning program for fast-neutron therapy at the FRM II research reactor in Garching, Germany. Depth dose curves were calculated inside a water phantom using measured primary neutron and simulated primary photon spectra and compared with depth dose curves measured earlier. The calculations were performed with GEANT4 in two different ways, simulating a simple box geometry and splitting this box into millions of small voxels (this was done to validate the voxelisation procedure that was also used to voxelise the human body).</p> <p>Results</p> <p>In both cases, the dose distributions were very similar to those measured in the water phantom, up to a depth of 30 cm. In order to model the situation of patients treated at the FRM II MEDAPP therapy beamline for salivary gland tumors, a human voxel phantom was implemented in GEANT4 and irradiated with the implemented MEDAPP neutron and photon spectra. The 3D dose distribution calculated inside the head of the phantom was similar to the depth dose curves in the water phantom, with some differences that are explained by differences in elementary composition. The lateral dose distribution was studied at various depths. The calculated cumulative dose volume histograms for the voxel phantom show the exposure of organs at risk surrounding the tumor.</p> <p>Conclusions</p> <p>In order to minimize the dose to healthy tissue, a conformal treatment is necessary. This can only be accomplished with the help of an advanced treatment planning system like the one developed here. Although all calculations were done for absorbed dose only, any biological dose weighting can be implemented easily, to take into account the increased radiobiological effectiveness of neutrons compared to photons.</p

    Visualizing Escherichia coli Sub-Cellular Structure Using Sparse Deconvolution Spatial Light Interference Tomography

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    Studying the 3D sub-cellular structure of living cells is essential to our understanding of biological function. However, tomographic imaging of live cells is challenging mainly because they are transparent, i.e., weakly scattering structures. Therefore, this type of imaging has been implemented largely using fluorescence techniques. While confocal fluorescence imaging is a common approach to achieve sectioning, it requires fluorescence probes that are often harmful to the living specimen. On the other hand, by using the intrinsic contrast of the structures it is possible to study living cells in a non-invasive manner. One method that provides high-resolution quantitative information about nanoscale structures is a broadband interferometric technique known as Spatial Light Interference Microscopy (SLIM). In addition to rendering quantitative phase information, when combined with a high numerical aperture objective, SLIM also provides excellent depth sectioning capabilities. However, like in all linear optical systems, SLIM's resolution is limited by diffraction. Here we present a novel 3D field deconvolution algorithm that exploits the sparsity of phase images and renders images with resolution beyond the diffraction limit. We employ this label-free method, called deconvolution Spatial Light Interference Tomography (dSLIT), to visualize coiled sub-cellular structures in E. coli cells which are most likely the cytoskeletal MreB protein and the division site regulating MinCDE proteins. Previously these structures have only been observed using specialized strains and plasmids and fluorescence techniques. Our results indicate that dSLIT can be employed to study such structures in a practical and non-invasive manner
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