A Remote Indicating Hinge-Moment Balance, Special Report

This report describes an electrical hinge-moment balance for use with wind-tunnel models of aircraft. A brief description of the principle of operation and operating experience with the balance is given in part I. Part II gives constructional details and part III gives theoretical considerations. Extensive constructional information is given to enable the reproduction of the equipment

Mechanism-based model characterizing bidirectional interaction between PEGylated liposomal CKD-602 (S-CKD602) and monocytes in cancer patients

S-CKD602 is a PEGylated liposomal formulation of CKD-602, a potent topoisomerase I inhibitor. The objective of this study was to characterize the bidirectional pharmacokinetic-pharmacodynamic (PK-PD) interaction between S-CKD602 and monocytes. Plasma concentrations of encapsulated CKD-602 and monocytes counts from 45 patients with solid tumors were collected following intravenous administration of S-CKD602 in the phase I study. The PK-PD models were developed and fit simultaneously to the PK-PD data, using NONMEM®. The monocytopenia after administration of S-CKD602 was described by direct toxicity to monocytes in a mechanism-based model, and by direct toxicity to progenitor cells in bone marrow in a myelosuppression-based model. The nonlinear PK disposition of S-CKD602 was described by linear degradation and irreversible binding to monocytes in the mechanism-based model, and Michaelis-Menten kinetics in the myelosuppression-based model. The mechanism-based PK-PD model characterized the nonlinear PK disposition, and the bidirectional PK-PD interaction between S-CKD602 and monocytes. © 2012 Cárdenas et al, publisher and licensee Dove Medical Press Ltd

Structural design options for the new 34 meter beam waveguide antenna

In addition to the successful network of 34 m High Efficiency antennas recently built by JPL, the Deep Space Network (DSN) is embarking on the construction of a 34 m high performance, research and development antenna with beam waveguide optics at the Venus site. The construction of this antenna presents many engineering challenges in the area of structural, mechanical, RF, and pointing system design. A set of functional and structural design requirements is outlined to guide analysts in the final configuration selection. Five design concepts are presented covering both the conventional center-fed beam optics as well as the nonconventional, by-pass beam configuration. The merits of each concept are discussed with an emphasis on obtaining a homologous design. The preliminary results of structural optimization efforts, currently in progress, are promising, indicating the feasibility of meeting, as a minimum, all X-band (8.4 GHz) requirements, with a goal towards meeting Ka-band (32 GHz) quality performance, at the present budget constraints

Cassini: Mission to Saturn and Titan

The Cassini Mission to Saturn and Titan represents an important step into the exploration of the outerplanets. It will expand on the flyby encounters of Pioneer and Voyager and parallel the detailed exploration of the Jupiter system to be accomplished by the Galileo Mission. By continuing the study of the two giant planets and enabling detailed comparisons of their structure and behavior, Cassini will provide a tremendous insight into the formation and evolution of the solar system. In addition, by virtue of its focus on the Saturnian satellite Titan, Cassini will return detailed data on an environment whose atmospheric chemistry may resemble that of the primitive Earth. The scientific objectives can be divided into five categories: Titan, Saturn, rings, icy satellites, and magnetospheres. The key area of interest to exobiologists is Titan; the other four scientific categories will be discussed briefly to provide a comprehensive overview of the Cassini Mission

Recurring Sacral Stress Fractures in the Male Distance Runner

Reccurring Sacral Stress Fractures in the Male Distance Runner Waugh TJ, Stoller GL, Brooks EK, Dailey SW: Miami University Oxford, Ohio Background: A twenty year old male collegiate distance runner (170 cm and 62 kg) complained of low back pain in March 2015. The patient reported right sided low back tightness that felt like a bad spasm traveling from the lower back down into the lower leg. History of this runner revealed a non-displaced stress fracture in the left sacral ala with a stress reaction on the right sacral ala in November 2013. In April 2014, the distance runner possessed yet another sacral stress fracture. In March 2015, an assessment was made that the patient presented an acute case of piriformis syndrome due to lack of athletic participation. As two weeks went by with no positive results through rehabilitation, worsening pain, and given the pre-existing conditions of the patient, the Team Physician ordered an MRI. Differential Diagnosis: It is possible that the runner could have had an acute disc herniation, muscle strain, degenerative disc disease, or spondylolisthesis. A vertebral compression fracture, sacroiliac joint dysfunction, lumbar facet arthropathy, and sciatica are all differential diagnoses that the clinicians in this case needed to be aware of. It is also important to assess the possibilities of a lumbosacral strain and a sacroiliac joint sprain. Treatment: The MRI report revealed a high grade stress reaction in the right sacral ala. A non-displaced stress fracture in the right superior portion of the left sacral ala was also discovered. The patient was told to rest without any exercise for four to six weeks. After the stress fracture was resolved, the athlete has been encouraged not to participate in any repeated load-bearing types of activities until the source of the problem has been identified. Uniqueness: There is an uncommon nature of sacral stress fractures in males. It is important to realize that individuals who are constantly participating in repeating load-bearing activities are more prone to sacral stress fractures. Sacral stress fractures normally present themselves in women who have the female athlete triad. Research has shown that the influence of energy balance and hormonal fluctuations are significant factors associated with injuries in amenorrheic female athletes. The testosterone levels in young men normally lead to healthy and strong bones. This case report is a prime example that has the potential to teach clinicians all over to always look at the big picture and keep in mind all of the possible differential diagnoses. Conclusions: Physician's have hypothesized that the calcium level in this patient is too high which is causing parathyroid levels to decrease, resulting in low bone density. Since calcium and the parathyroid hormone have an inverse relationship, moderation between the two is essential. However, if one is too high, the other is too low decreasing bone density. Another hypothesis is that low testosterone levels in the patient are causing low bone density. This rare case is far from over as there is numerous investigative work to still be done. Clinical Application: Correctly diagnosing a sacral stress fracture is very difficult due to the wide range of differential diagnoses that its symptoms can present. Clinicians should never rule out the possibility of a sacral stress fracture when clients present low back pain, diffuse buttocks pain, and a history of repetitive loading actively. Although the clinicians in this case did not originally think this injury was another sacral stress fracture, they never ruled out the possibility due to the patient's described pain and pre-existing conditions. The clinicians in this report considered all possible diagnoses before making an assessment. Further research still needs to be performed in order to provide the most effective treatment and outcomes for future patients. Word Count: 59

Neural Simplex Architecture

We present the Neural Simplex Architecture (NSA), a new approach to runtime assurance that provides safety guarantees for neural controllers (obtained e.g. using reinforcement learning) of autonomous and other complex systems without unduly sacrificing performance. NSA is inspired by the Simplex control architecture of Sha et al., but with some significant differences. In the traditional approach, the advanced controller (AC) is treated as a black box; when the decision module switches control to the baseline controller (BC), the BC remains in control forever. There is relatively little work on switching control back to the AC, and there are no techniques for correcting the AC's behavior after it generates a potentially unsafe control input that causes a failover to the BC. Our NSA addresses both of these limitations. NSA not only provides safety assurances in the presence of a possibly unsafe neural controller, but can also improve the safety of such a controller in an online setting via retraining, without overly degrading its performance. To demonstrate NSA's benefits, we have conducted several significant case studies in the continuous control domain. These include a target-seeking ground rover navigating an obstacle field, and a neural controller for an artificial pancreas system.Comment: 12th NASA Formal Methods Symposium (NFM 2020

Monitoring Partially Synchronous Distributed Systems using SMT Solvers

In this paper, we discuss the feasibility of monitoring partially synchronous distributed systems to detect latent bugs, i.e., errors caused by concurrency and race conditions among concurrent processes. We present a monitoring framework where we model both system constraints and latent bugs as Satisfiability Modulo Theories (SMT) formulas, and we detect the presence of latent bugs using an SMT solver. We demonstrate the feasibility of our framework using both synthetic applications where latent bugs occur at any time with random probability and an application involving exclusive access to a shared resource with a subtle timing bug. We illustrate how the time required for verification is affected by parameters such as communication frequency, latency, and clock skew. Our results show that our framework can be used for real-life applications, and because our framework uses SMT solvers, the range of appropriate applications will increase as these solvers become more efficient over time.Comment: Technical Report corresponding to the paper accepted at Runtime Verification (RV) 201