The Intergalactic Propagation of Ultra-High Energy Cosmic Ray Nuclei: An Analytic Approach

It is likely that ultra-high energy cosmic rays contain a significant component of heavy or intermediate mass nuclei. The propagation of ultra-high energy nuclei through cosmic radiation backgrounds is more complicated than that of protons and its study has required the use of Monte Carlo techniques. We present an analytic method for calculating the spectrum and the composition at Earth of ultra-high energy cosmic rays which start out as heavy nuclei from their extragalactic sources. The results obtained are in good agreement with those obtained using numerical methods.Comment: accepted for publication in Phys Rev

High-Throughput Classification of Radiographs Using Deep Convolutional Neural Networks.

The study aimed to determine if computer vision techniques rooted in deep learning can use a small set of radiographs to perform clinically relevant image classification with high fidelity. One thousand eight hundred eighty-five chest radiographs on 909 patients obtained between January 2013 and July 2015 at our institution were retrieved and anonymized. The source images were manually annotated as frontal or lateral and randomly divided into training, validation, and test sets. Training and validation sets were augmented to over 150,000 images using standard image manipulations. We then pre-trained a series of deep convolutional networks based on the open-source GoogLeNet with various transformations of the open-source ImageNet (non-radiology) images. These trained networks were then fine-tuned using the original and augmented radiology images. The model with highest validation accuracy was applied to our institutional test set and a publicly available set. Accuracy was assessed by using the Youden Index to set a binary cutoff for frontal or lateral classification. This retrospective study was IRB approved prior to initiation. A network pre-trained on 1.2 million greyscale ImageNet images and fine-tuned on augmented radiographs was chosen. The binary classification method correctly classified 100 % (95 % CI 99.73-100 %) of both our test set and the publicly available images. Classification was rapid, at 38 images per second. A deep convolutional neural network created using non-radiological images, and an augmented set of radiographs is effective in highly accurate classification of chest radiograph view type and is a feasible, rapid method for high-throughput annotation

Prospects and Pitfalls of Pregnancy-Associated Malaria Vaccination Based on the Natural Immune Response to Plasmodium falciparum VAR2CSA-Expressing Parasites

Pregnancy-associated malaria, a manifestation of severe malaria, is the cause of up to 200,000 infant deaths a year, through the effects of placental insufficiency leading to growth restriction and preterm delivery. Development of a vaccine is one strategy for control. Plasmodium falciparum-infected red blood cells accumulate in the placenta through specific binding of pregnancy-associated parasite variants that express the VAR2CSA antigen to chondroitin sulphate A on the surface of syncytiotrophoblast cells. Parasite accumulation, accompanied by an inflammatory infiltrate, disrupts the cytokine balance of pregnancy with the potential to cause placental damage and compromise foetal growth. Multigravid women develop immunity towards VAR2CSA-expressing parasites in a gravidity-dependent manner which prevents unfavourable pregnancy outcomes. Although current vaccine design, targeting VAR2CSA antigens, has succeeded in inducing antibodies artificially, this candidate may not provide protection during the first trimester and may only protect those women living in areas endemic for malaria. It is concluded that while insufficient information about placental-parasite interactions is presently available to produce an effective vaccine, incremental progress is being made towards achieving this goal

AN ECONOMIC ANALYSIS OF THE NORTH DAKOTA CATTLE INDUSTRY

The analysis was conducted to evaluate the impacts of both the Federal Agricultural Improvement and Reform Act of 1996 (FAIR) and the cattle cycle on the livestock enterprises. The North Dakota Representative Farm and Ranch Model, which uses the Food and Agricultural Policy Research Institute price projections as an input, was developed and used for this analysis. Net farm income and farm debt-to-asset ratios for the average and large beef cattle farms were analyzed. The U.S. cattle industry has been characterized by cyclical variations in production and prices. It appears that the current cattle cycle is in the final stages of expansion. Cattle numbers continued to increase during 1995, but at a slow rate. Industry estimates are that the bottom of cattle prices will occur in late 1996 or 1997. Price recovery is projected to start sometime in 1998 as inventory numbers decline. Prices are forecast to rise through 2002. Net farm income for the representative beef cattle farms is projected to follow the cattle cycle with the lowest net incomes during 1997- 1999. Net farm income for most representative beef cattle farms recovers by 2002-2003. The debt-to-asset ratios for the representative beef cattle farms will likely rise throughout the forecast period. FAPRI Note: Figures are not included in the machine readable copy--contact the authors for more information.livestock, representative farms, cattle cycle, Production Economics,

The Spectral Shape and Photon Fraction as Signatures of the GZK-Cutoff

With the prospect of measuring the fraction of arriving secondary photons, produced through photo-pion energy loss interactions of ultra high energy cosmic ray (UHECR) protons with the microwave background during propagation, we investigate how information about the local UHECR source distribution can be inferred from the primary (proton) to secondary (photon) ratio. As an aid to achieve this, we develop an analytic description for both particle populations as a function of propagation time. Through a consideration of the shape of the GZK cut-off and the corresponding photon fraction curve, we investigate the different results expected for both different maximum proton energies injected by the sources, as well as a change in the local source distribution following a perturbative deformation away from a homogeneous description. At the end of the paper, consideration is made as to how these results are modified through extra-galactic magnetic field effects on proton propagation. The paper aims to demonstrate how the shape of the cosmic ray flux in the cut-off region, along with the photon fraction, are useful indicators of the cutoff origin as well as the local UHECR source distribution.Comment: Accepted for publication in PRD, 12 pages, 9 figure

Structural Characterization of the Rhenium(V) Oxo Complex of Mercaptoacetyltriglyclne in its Dianionic Form

Dianionic [MO(MAG3)]2−(MAG3 = penta-anionic form of mercaptoacetyltriglycine, M = 186Re, 99mTc) complexes have important applications in nuclear medicine. In vivo the complexes have a deprotonated carboxyl group that is important to their biodistribution. The solid-state structures of 99Tc and Re complexes with mercaptoacetyltriglycine reported previously are monoanions with protonated carboxyl groups. In the present work, we report the preparation and X-ray crystal structure of Na2[ReO(MAG3)]·5H2O (1), which contains the physiologically relevant dianion. The dianion is a distorted square pyramid with the nitrogen and sulphur donor atoms forming the base and the oxo ligand at the apex. The terminal carboxyl group is deprotonated, uncoordinated and has a syn orientation with respect to the oxo ligand. The syn conformation of the dianion in 1 differs in conformation from the anti-monoanion in [Bu4N][ReO(MAG3H)] but is similar to the syn-monoanion in [Ph4P][99TcO(MAG3 H)]

Synthesis of the Sulphonate and Phosphonate Derivatives of Mercaptoacetyltriglycine. X-Ray Crystal Structure of Na2[ReO(Mercaptoacetylglycylglycylaminomethanesulphonate)]·3H2O

Mercaptoacetyltriglycine forms complexes with 186/188Re and 99mTc radionuclides that are useful in nuclear medicine because they are substrates of the renal anion transport system. However, the renal clearance of [MO(MAG3)]2-(MAG3 = penta-anionic form of mercaptoacetyltriglycine, M = Re, Tc) complexes are less than ideal. Organic sulphonates are also transported by the renal anion transport system and phosphonates are similar to sulphonates in size and shape. In an effort to develop new ligands that form Re and Tc complexes and have improved renal clearances compared to [MO(MAG3)]2- complexes, the sulphonate and phosphonate derivatives of mercaptoacetyltriglycine were synthesized. The dianion [ReO(MAG2-AMS)]2- (MAG2-AMS = penta-anionic form of mercaptoacetylglycylglycylaminomethanesulphonic acid) was prepared for characterization by exchange reaction of ReOCl3(Me2S)(OPPh3) and isolated as the disodium salt. The structure of Na2[ReO(MAG2-AMS)]·3H2O (6) was determined by X-ray diffraction. The coordination geometry is pseudo square pyramidal, with the nitrogen and sulfur donor atoms forming a square base and the oxo ligand at the apex. The deprotonated sulphonate group has a syn conformation with respect to the oxo ligand. The renal clearances of [99mTcO(MAG2-AMS)]2- and [99mTcO(MAG2-AMP)]3- were similar in rats and suggest that the difference in total charge between the SO3- and PO32- groups is not important to renal clearance. However, their renal clearances were 40-50% less than that of [99mTcO(MAG3)]2- suggesting that the size and shape of the large tetrahedral SO3- and PO32- groups of [99mTcO(MAG2-AMS)]2- and [99mTcO(MAG2-AMP)]3- inhibit recognition by the renal transport system compared to the small planar CO2- group of [99mTcO(MAG3)]2-

Modelling bispecific monoclonal antibody interaction with two cell membrane targets indicates the importance of surface diffusion

We have developed a mathematical framework for describing a bispecific monoclonal antibody interaction with two independent membrane-bound targets that are expressed on the same cell surface. The bispecific antibody in solution binds either of the two targets first, and then cross-links with the second one whilst on the cell surface, subject to rate-limiting lateral diffusion step within the lifetime of the monovalently engaged antibody-antigen complex. At experimental densities, only a small fraction of the free targets is expected to lie within the reach of the antibody binding sites at any time. Using ordinary differential equation and Monte Carlo simulation-based models, we validated this approach against an independently published anti-CD4/CD70 DuetMab experimental data set. As a result of dimensional reduction, the cell surface reaction is expected to be so rapid that, in agreement with the experimental data, no monovalently bound bispecific antibody binary complexes accumulate until cross-linking is complete. The dissociation of the bispecific antibody from the ternary cross-linked complex is expected to be significantly slower than that from either of the monovalently bound variants. We estimate that the effective affinity of the bivalently bound bispecific antibody is enhanced for about four orders of magnitude over that of the monovalently bound species. This avidity enhancement allows for the highly specific binding of anti-CD4/CD70 DuetMab to the cells that are positive for both target antigens over those that express only one or the other We suggest that the lateral diffusion of target antigens in the cell membrane also plays a key role in the avidity effect of natural antibodies and other bivalent ligands in their interactions with their respective cell surface receptors

Automatic georeferencing of astronaut auroral photography

Astronauts on board the International Space Station (ISS) have taken thousands of high-resolution colour photographs of the aurora, which could be made useful for research if their pointing information could be reconstructed. We describe a method to do this using the star field in the images, and how the reconstructed pointing can then be used to georeference the images to a similar level of accuracy in existing all-sky camera images. We have used this method to make georeferenced auroral images taken from the ISS available and here describe the resulting data set, processing software, and how to access them