Communication system features dual mode range acquisition plus time delay measurement

Communication system combines range acquisition system and time measurement system for tracking high velocity aircraft and spacecraft. The range acquisition system uses a pseudonoise code to determine range and the time measurement system reduces uncontrolled phase variations in the demodulated signal

In-flight determination of spacecraft magnetic bias independent of attitude

A simple algorithm for the in-flight determination of the magnetic bias of a spacecraft is presented. The algorithm, developed for use during the Hubble Space Telescope mission, determines this bias independently of any attitude estimates and requires no spacecraft sensor data other than that from the spacecraft magnetometer(s). Estimates of the algorithm's accuracy and results from a number of numerical studies on the use of this algorithm are also presented

Towards case-based medical learning in radiological decision making using content-based image retrieval

<p>Abstract</p> <p>Background</p> <p>Radiologists' training is based on intensive practice and can be improved with the use of diagnostic training systems. However, existing systems typically require laboriously prepared training cases and lack integration into the clinical environment with a proper learning scenario. Consequently, diagnostic training systems advancing decision-making skills are not well established in radiological education.</p> <p>Methods</p> <p>We investigated didactic concepts and appraised methods appropriate to the radiology domain, as follows: (i) Adult learning theories stress the importance of work-related practice gained in a team of problem-solvers; (ii) Case-based reasoning (CBR) parallels the human problem-solving process; (iii) Content-based image retrieval (CBIR) can be useful for computer-aided diagnosis (CAD). To overcome the known drawbacks of existing learning systems, we developed the concept of image-based case retrieval for radiological education (IBCR-RE). The IBCR-RE diagnostic training is embedded into a didactic framework based on the Seven Jump approach, which is well established in problem-based learning (PBL). In order to provide a learning environment that is as similar as possible to radiological practice, we have analysed the radiological workflow and environment.</p> <p>Results</p> <p>We mapped the IBCR-RE diagnostic training approach into the Image Retrieval in Medical Applications (IRMA) framework, resulting in the proposed concept of the IRMAdiag training application. IRMAdiag makes use of the modular structure of IRMA and comprises (i) the IRMA core, i.e., the IRMA CBIR engine; and (ii) the IRMAcon viewer. We propose embedding IRMAdiag into hospital information technology (IT) infrastructure using the standard protocols Digital Imaging and Communications in Medicine (DICOM) and Health Level Seven (HL7). Furthermore, we present a case description and a scheme of planned evaluations to comprehensively assess the system.</p> <p>Conclusions</p> <p>The IBCR-RE paradigm incorporates a novel combination of essential aspects of diagnostic learning in radiology: (i) Provision of work-relevant experiences in a training environment integrated into the radiologist's working context; (ii) Up-to-date training cases that do not require cumbersome preparation because they are provided by routinely generated electronic medical records; (iii) Support of the way adults learn while remaining suitable for the patient- and problem-oriented nature of medicine. Future work will address unanswered questions to complete the implementation of the IRMAdiag trainer.</p

Mobile Phones as Secure Gateways for Message-Based Ubiquitous Communication (Revised)

For ubiquitous communication self-organising ad-hoc networks become more and more important. We consider mobile phones as appropriate secure gateways to provide access to the Internet for external machines with low communication needs. A message-based approach is best in such a scenario with moving mobile phones and machines. In this paper we propose a security model for access control to the communication infrastructure, which is also message oriented. To meet the requirements of ubiquitously communicating machines, all algorithms on the sender\u27s side are based on symmetric cryptography resulting in low computation requirements. Our sophisticated symmetric key infrastructure for access control is based on unique combinations of keys and is completed with an effective key management. This results in a carrier grade security level although many parties share the same keys. Adopting the Subscriber Identity Module as a secure storage and computing module achieves the trustworthiness of the mobile phone. This makes it possible to use the mobile phone not only as a user terminal but also as a trusted infrastructure component of the mobile network. This document is an update of earlier work [BWS07] presented at the Workshop in Information Security Theory and Practices 2007 in Crete, Greece

In renal cell carcinoma the PTEN splice variant PTEN-Δ shows similar function as the tumor suppressor PTEN itself

BACKGROUND: Loss of PTEN is involved in tumor progression of several tumor entities including renal cell carcinoma (RCC). During the translation process PTEN generates a number of splice variants, including PTEN-Δ. We analyzed the impact of PTEN-Δ in RCC progression. METHODS: In specimens of RCC patients the expression of PTEN-Δ and PTEN was quantified. The PTEN expressing RCC cell line A498 and the PTEN deficient 786-O cell line were stably transfected with the PTEN-Δ or PTEN transcript. In Caki-1 cells that highly express PTEN-Δ, this isoform was knocked down by siRNA. Cell migration, adhesion, apoptosis and signaling pathways activities were consequently analyzed in vitro. RESULTS: Patients with a higher PTEN-Δ expression had a longer lymph node metastasis free and overall survival. In RCC specimens, the PTEN-Δ expression correlated with the PTEN expression. PTEN-Δ as well as PTEN induced a reduced migration when using extracellular matrix (ECM) compounds as chemotaxins. This effect was confirmed by knockdown of PTEN-Δ, inducing an enhanced migration. Likewise a decreased adhesion on these ECM components could be shown in PTEN-Δ and PTEN transfected cells. The apoptosis rate was slightly increased by PTEN-Δ. In a phospho-kinase array and Western blot analyses a consequently reduced activity of AKT, p38 and JNK could be shown. CONCLUSIONS: We could show that the PTEN splice variant PTEN-Δ acts similar to PTEN in a tumor suppressive manner, suggesting synergistic effects of the two isoforms. The impact of PTEN-Δ in context of tumor progression should thus be taken into account when generating new therapeutic options targeting PTEN signaling in RCC

Immuno-Electrophysiological Mechanisms of Functional Electrical Connections Between Recipient and Donor Heart in Patients With Orthotopic Heart Transplantation Presenting With Atrial Arrhythmias

[EN] BACKGROUND: The formation of recipient-to donor atrio-atrial connections (AAC) in patients after orthotopic heart transplantation (OHT) is poorly understood. We sought to investigate the mechanisms of atrial tachyarrhythmias after OHT, the role of AACs, and their relationship to the immunologic match. METHODS: In a large series of OHT patients, we performed a retrospective review of 42 patients who underwent catheter ablation for atrial arrhythmias. A realistic 3-dimensional computer model of human atria was used to study AAC conductivity. RESULTS: Patient age was 55 +/- 15 years (71% male). Biatrial anastomosis was present in 24/42 patients (57%). An AAC was found in 9/42 patients (21%, right-sided in 5 patients with biatrial anastomosis, left-sided in 4 patients). The AAC became apparent at the time of the electrophysiology study 10.1 +/- 7.6 years after OHT (range, 0.3-22.2 years). Donor-specific antibodies were present in no patient with AAC but were present in 69% of patients without AAC, P=0.002. In all patients with AAC, a recipient atrial tachycardia propagated via AAC to the donor atrium (4 patients presented with atrial fibrillation). Simulations showed AAC conduction requires an isthmus of >= 2 mm and is cycle length and location dependent. Patients without AAC (n=13) frequently presented with donor atrial arrhythmias, in 77% cavo-tricuspid isthmus flutter was ablated. The procedural success was high, although, 12 patients (29%) required reablation. CONCLUSIONS: AACs are found in 21% of OHT patients with atrial tachyarrhythmias and can manifest very early after OHT. Immune privilege characterized by the absence of donor-specific antibodies may facilitate AAC formation. Propagation across an AAC is width, cycle length, and location dependent. Patients with AAC present with focal atrial tachycardias or atrial fibrillation originating from the recipient atria; patients without most frequently present with cavo-tricuspid isthmus dependent atrial flutter. While multiple arrhythmias frequently require reablation, ablative therapy is highly effective.This study was supported in part by National Institutes of Health grants R21HL138064, and R01HL129136 to Dr Noujaim. This work was partially supported by the Direccion General de Politica Cientifica de la Generalitat Valenciana (PROMETEU2020/043).Herweg, B.; Nellaiyappan, M.; Welter-Frost, AM.; Tran, T.; Mabry, G.; Weston, K.; Tobón, C.... (2021). Immuno-Electrophysiological Mechanisms of Functional Electrical Connections Between Recipient and Donor Heart in Patients With Orthotopic Heart Transplantation Presenting With Atrial Arrhythmias. Circulation Arrhythmia and Electrophysiology. 14(4):412-423. https://doi.org/10.1161/CIRCEP.120.008751S41242314