Fermionic Quasi-free States and Maps in Information Theory

This paper and the results therein are geared towards building a basic toolbox for calculations in quantum information theory of quasi-free fermionic systems. Various entropy and relative entropy measures are discussed and the calculation of these reduced to evaluating functions on the one-particle component of quasi-free states. The set of quasi-free affine maps on the state space is determined and fully characterized in terms of operations on one-particle subspaces. For a subclass of trace preserving completely positive maps and for their duals, Choi matrices and Jamiolkowski states are discussed.Comment: 19 page

Characterization for fusion first-wall damage studies of using tailored D-T neutron fields

The approximation required to apply the Bullough-Haynes results to the present calculations is somewhat crude and may imply that the details of the results contain considerable error. However, when the results for each neutron source are viewed in a relative context, several valid and important observations can be made. The almost identical swelling results obtained for the intense neutron source (INS) with a standard blanket and the fusion first wall are most striking. A further comparison with a fusion reactor shows that even the spatial and energy distributions of the neutron flux are similar. In both the INS with blanket and at the first wall of a fusion reactor, there is a radial source flux component of 14-MeV neutrons and a more or less isotropic flux component of low energy (< 14-MeV) neutrons. One must therefore conclude that from the point-of-view of neutron radiation damage, the INS with a blanket, unlike all other types of neutron sources, is not a simulation environment. It is, in fact, a small scale fusion device, and data obtained from INS irradiation experiments would represent fusion reactor results. Such data could then be used to develop correlative procedures for applying data obtained from other simulation sources to fusion reactor conditions

Adaptive Path Planning for Depth Constrained Bathymetric Mapping with an Autonomous Surface Vessel

This paper describes the design, implementation and testing of a suite of algorithms to enable depth constrained autonomous bathymetric (underwater topography) mapping by an Autonomous Surface Vessel (ASV). Given a target depth and a bounding polygon, the ASV will find and follow the intersection of the bounding polygon and the depth contour as modeled online with a Gaussian Process (GP). This intersection, once mapped, will then be used as a boundary within which a path will be planned for coverage to build a map of the Bathymetry. Methods for sequential updates to GP's are described allowing online fitting, prediction and hyper-parameter optimisation on a small embedded PC. New algorithms are introduced for the partitioning of convex polygons to allow efficient path planning for coverage. These algorithms are tested both in simulation and in the field with a small twin hull differential thrust vessel built for the task.Comment: 21 pages, 9 Figures, 1 Table. Submitted to The Journal of Field Robotic

Radiolabeled humanized anti-CD3 monoclonal antibody visilizumab for imaging human T-lymphocytes

Visilizumab is an IgG2 humanized monoclonal antibody (mAb) characterized by non-FcγR binding and specific to the CD3 antigen, expressed on more than 95% of circulating resting T-lymphocytes and on activated T-lymphocytes homing in inflamed tissues. We hypothesized that the use of a radiolabeled anti-CD3 antibody might serve as a diagnostic tool for imaging T-cell traffic and lymphocytic infiltration of tissues and organs affected by autoimmune diseases. Here we describe the results of in vitro and animal experiments with 99mTc-succinimidyl-6-hydrazinonicotinate hydrochloride (SHNH)-visilizumab. Methods: For mAb labeling, we used a 2-step method with a heterobifunctional linker SHNH. Several titrations were performed to obtain the best labeling efficiency. In vitro quality controls included stability assay, cysteine challenge, sodium dodecyl sulfate polyacrylamide gel electrophoresis, binding assay, and immunoreactivity assay. In vivo studies by high-resolution images were performed at 6 and 24 h after the injection of 99mTc-SHNH-visilizumab. These included cell-targeting experiments in BALB/c mice xenografted subcutaneously with an increasing number of HuT78 cells in the leg and displaced with an excess of cold antibody. We also studied irradiated severe combined immunodeficient (SCID) mice reconstituted with human peripheral blood mononuclear cells (hPBMCs) and injected with 99mTclabeled visilizumab or control mAb. After dynamic imaging for 3 h, major organs were removed, counted, and processed for immunohistologic examination. Results: Visilizumab was labeled with HYNIC with high labeling efficiency (>90%) and high specific activity (SA; 10,360-11,100 MBq/mg), with retained biochemical integrity and in vitro binding activity to CD3-positive cells. The in vivo targeting experiment showed a proportional increase of specific uptake with the number of injected cells, both at 6 and at 24 h, and the in vivo competition study demonstrated more than 60% decreased uptake after an excess of unlabeled antibody. In SCID mice, hPBMCs in different tissues were detected by 99mTc-labeled visilizumab and confirmed by histology. Conclusion: Visilizumab can be efficiently labeled with 99mTc with high efficiency and SA and could be a valuable tool for the study of human T-lymphocyte trafficking and lymphocytic infiltration of tissues and organs. Copyright © 2009 by the Society of Nuclear Medicine, Inc

Recommendations in Second Opinion Reports of Neurologic Head and Neck Imaging:Frequency, Referring Clinicians? Compliance, and Diagnostic Yield

BACKGROUND AND PURPOSE: Second opinion reports of neurologic head and neck imaging are requested with increased regularity, and they may contain a recommendation to the clinician. Our aim was to investigate the frequency and determinants of the presence of a recommendation and the adherence by the referring physician to the recommendation in a second opinion neurology head and neck imaging report and the diagnostic yield of these recommendations. MATERIALS AND METHODS: This retrospective study included 994 consecutive second opinion reports of neurology head and neck imaging examinations performed at a tertiary care center. RESULTS: Of the 994 second opinion reports, 12.2% (121/994) contained a recommendation. An oncologic imaging indication was significantly (P = .030) associated with a lower chance of a recommendation in the second opinion report (OR = .67; 95% CI, 0.46?0.96). Clinicians followed 65.7% (88/134) of the recommendations. None of the investigated variables (patient age, sex, hospitalization status, indication for the second opinion report, experience of the radiologist who signed the second opinion report, strength of the recommendation, and whether the recommendation was made due to apparent quality issues of the original examination) were significantly associated with the compliance of the referring physician to this recommendation. The 134 individual recommendations eventually led to the establishment of 52 (38.2%) benign diagnoses and 28 (20.6%) malignant diagnoses, while no definitive diagnosis could be established in 56 (41.2%) cases. CONCLUSIONS: Recommendations are relatively common in second opinion reports of neurology head and neck imaging examinations, though less for oncologic indications. They are mostly followed by requesting physicians, thus affecting patient management. In most cases, they also lead to the establishment of a diagnosis, hence adding value to patient care

Rapid reduction of sigma(1)-Receptor binding and F-18-FDG uptake in rat gliomas after in vivo treatment with doxorubicin

sigma-Receptors are strongly overexpressed in most rodent and human tumors and are proliferation markers. To evaluate the potential of a radiolabeled sigma(1)-ligand for therapy monitoring, we compared early changes of C-11-1-(3,4-dimethoxyphenethyl)-4-(3-phenylpropyl)piperazine (C-11-SA4503) binding and F-18-FDG uptake in gliomas after in vivo chemotherapy. Methods: C6 cells (2.5 x 10(6)) were subcutaneously injected into the right shoulder of male Wistar rats. After 7 cl, the tumor volume was 0.60 +/- 0.08 cm(3). Animals then received either saline or doxorubicin (8 mg/kg, intraperitoneally). One control and 1 treated rat were imaged simultaneously, 24 or 48 h after treatment, under pentobarbital anesthesia. Rodents (n = 20) were scanned first with C-11-SA4503 (25 MBq, intravenously) followed more than 100 min afterward by 18F-FDG (20 MBq, intravenously), using a dedicated small-animal PET camera (60-min protocol, tumors in the field of view). Tumor homogenates were prepared and subjected to sigma-receptor assays. The biodistribution of 18F-FDG was assessed. Results: Tumors appeared 4-5 d after inoculation and grew exponentially. No significant reduction of tumor growth was visible within 48 h after doxorubicin treatment. Both PET tracers visualized the tumors and showed reduced uptake after chemotherapy (C-11-SA4503: 26.5% +/- 6.5% at 24 h, 26.5% +/- 7.5% at 48 h; 18F-FDG: 22.6% +/- 3.2% at 24 h, 27.4% +/- 3.2% at 48 h; ex vivo F-18-FDG: 22.4% +/- 5.4% at 24 h, 31.7% +/- 12.7% at 48 h). sigma(1)-Receptor density in treated tumors was also reduced (from 172 +/- 35 to 125 +/- 28 fmol/mg of protein). Conclusion: Both C-11-SA4503 binding and 18F-FDG uptake declined in gliomas after chemotherapy. Decreased binding of C-11-SA4503 corresponded to a loss of (sigma(1)-receptors from the tumors. Changes in tracer uptake preceded the morphologic changes by at least 48 h

Time to Reconsider Routine Percutaneous Biopsy in Spondylodiscitis?

Percutaneous image-guided biopsy currently has a central role in the diagnostic work-up of patients with suspected spondylodiscitis. However, on the basis of recent evidence, the value of routine image-guided biopsy in this disease can be challenged. In this article, we discuss this recent evidence and also share a new diagnostic algorithm for spondylodiscitis that was recently introduced at our institution. Thus, we may move from a rather dogmatic approach in which routine image-guided biopsy is performed in any case to a more individualized use of this procedure. Percutaneous image-guided biopsy, while valuable, is an invasive procedure, and evidence has shown rather disappointing positive microbiologic culture yields of around 33%. Recent evidence also has shown that percutaneous image-guided biopsy rarely adds any new information when blood cultures have positive findings and that an effective empiric treatment can be started in most of cases even when the microbiologic culprit remains unknown. Finally, there is currently no evidence that percutaneous image-guided biopsy improves patient outcome

Preliminary findings from a multi-robot system for large-scale extra-planetary additive construction

We present our findings from a 4-day workshop at SmartGeometry2016, during which the authors conducted an open-ended experiment to ascertain the viability of a multi-robotic system capable of large-scale additive construction with sand. The study and results pertain to future robotic systems operating in extreme environments, such as in lunar or Martian conditions, where there is a need for autonomous construction of regolith structures for infrastructure or human habitat protection. The purposes of this study were to: i) implement and document the practical knowledge of multi- or swarm-robot systems in physically realistic environments; ii) ascertain the feasibility of additive construction with many-simple rather than few-complex robots; and iii) explore individual behavioural rules for the robots which, although indirectly controlled themselves, can result in a controlled outcome. Behaviour is understood as the interactions between an individual and its environment where the behaviour of the individual affects its own perceptions, and thus its future actions and perceptions. Applying this concept to robots results in a field of autonomous behavioural machines capable of operating in partially unknown and changing environments without human intervention. In the paper we describe the design and mechanical operation of the multi-robot system, the local positioning and communication system, ending with a discussion of the programmed behaviours and the final workshop outcomes. The results of this workshop will be used to inform the next stage of the technology demonstration in which the process will be scaled up

SMART (SiMulAtion and ReconsTruction) PET:an efficient PET simulation-reconstruction tool

Background: Positron-emission tomography (PET) simulators are frequently used for development and performance evaluation of segmentation methods or quantitative uptake metrics. To date, most PET simulation tools are based on Monte Carlo simulations, which are computationally demanding. Other analytical simulation tools lack the implementation of time of flight (TOF) or resolution modelling (RM). In this study, a fast and easy-to-use PET simulation-reconstruction package, SiMulAtion and ReconsTruction (SMART)-PET, is developed and validated, which includes both TOF and RM. SMART-PET, its documentation and instructions to calibrate the tool to a specific PET/CT system are available on Zenodo.SMART-PET allows the fast generation of 3D PET images. As input, it requires one image representing the activity distribution and one representing the corresponding CT image/attenuation map. It allows the user to adjust different parameters, such as reconstruction settings (TOF/RM), noise level or scan duration. Furthermore, a random spatial shift can be included, representing patient repositioning. To evaluate the tool, simulated images were compared with real scan data of the NEMA NU 2 image quality phantom. The scan was acquired as a 60-min list-mode scan and reconstructed with and without TOF and/or RM. For every reconstruction setting, ten statistically equivalent images, representing 30, 60, 120 and 300 s scan duration, were generated. Simulated and real-scan data were compared regarding coefficient of variation in the phantom background and activity recovery coefficients (RCs) of the spheres. Furthermore, standard deviation images of each of the ten statistically equivalent images were compared.Results: SMART-PET produces images comparable to actual phantom data. The image characteristics of simulated and real PET images varied in similar ways as function of reconstruction protocols and noise levels. The change in image noise with variation of simulated TOF settings followed the theoretically expected behaviour. RC as function of sphere size agreed within 0.3-11% between simulated and actual phantom data.Conclusions: SMART-PET allows for rapid and easy simulation of PET data. The user can change various acquisition and reconstruction settings (including RM and TOF) and noise levels. The images obtained show similar image characteristics as those seen in actual phantom data.</p

In vivo imaging of brain androgen receptors in rats: a [18F]FDHT PET study

AbstractIntroductionSteroid hormones like androgens play an important role in the development and maintenance of several brain functions. Androgens can act through androgen receptors (AR) in the brain. This study aims to demonstrate the feasibility of positron emission tomography (PET) with 16β-[18F]fluoro-5α-dihydrotestosterone ([18F]FDHT) to image AR expression in the brain.MethodsMale Wistar rats were either orchiectomized to inhibit endogenous androgen production or underwent sham-surgery. Fifteen days after surgery, rats were subjected to a 90-min dynamic [18F]FDHT PET scan with arterial blood sampling. In a subset of orchiectomized rats, 1mg/kg dihydrotestosterone was co-injected with the tracer in order to saturate the AR. Plasma samples were analyzed for the presence of radioactive metabolites by radio-TLC. Pharmacokinetic modeling was performed to quantify brain kinetics of the tracer. After the PET scan, the animals were terminated for ex-vivo biodistribution.ResultsPET imaging and ex vivo biodistribution studies showed low [18F]FDHT uptake in all brain regions, except pituitary. [18F]FDHT uptake in the surrounding cranial bones was high and increased over time. [18F]FDHT was rapidly metabolized in rats. Metabolism was significantly faster in orchiectomized rats than in sham-orchiectomized rats. Quantitative analysis of PET data indicated substantial spill-over of activity from cranial bones into peripheral brain regions, which prevented further analysis of peripheral brain regions. Logan graphical analysis and kinetic modeling using 1- and 2-tissue compartment models showed reversible and homogenously distributed tracer uptake in central brain regions. [18F]FDHT uptake in the brain could not be blocked by endogenous androgens or administration of dihydrotestosterone.ConclusionThe results of this study indicate that imaging of AR availability in rat brain with [18F]FDHT PET is not feasible. The low AR expression in the brain, the rapid metabolism of [18F]FDHT in rats and the poor brain penetration of the tracer likely contributed to the poor performance of [18F]FDHT PET in this study