Hardware simulation of Ku-band spacecraft receiver and bit synchronizer, volume 1

A hardware simulation which emulates an automatically acquiring transmit receive spread spectrum communication and tracking system and developed for use in future NASA programs involving digital communications is considered. The system architecture and tradeoff analysis that led to the selection of the system to be simulated is presented

Hardware simulation of KU-band spacecraft receiver and bit synchronizer, phase 2, volume 1

The acquisition behavior of the PN subsystem of an automatically acquiring spacecraft receiver was studied. A symbol synchronizer subsystem was constructed and integrated into the composite simulation of the receiver. The overall performance of the receiver when subjected to anomalies such as signal fades was evaluated. Potential problems associated with PN/carrier sweep interactions were investigated

Ions in Fluctuating Channels: Transistors Alive

Ion channels are proteins with a hole down the middle embedded in cell membranes. Membranes form insulating structures and the channels through them allow and control the movement of charged particles, spherical ions, mostly Na+, K+, Ca++, and Cl-. Membranes contain hundreds or thousands of types of channels, fluctuating between open conducting, and closed insulating states. Channels control an enormous range of biological function by opening and closing in response to specific stimuli using mechanisms that are not yet understood in physical language. Open channels conduct current of charged particles following laws of Brownian movement of charged spheres rather like the laws of electrodiffusion of quasi-particles in semiconductors. Open channels select between similar ions using a combination of electrostatic and 'crowded charge' (Lennard-Jones) forces. The specific location of atoms and the exact atomic structure of the channel protein seems much less important than certain properties of the structure, namely the volume accessible to ions and the effective density of fixed and polarization charge. There is no sign of other chemical effects like delocalization of electron orbitals between ions and the channel protein. Channels play a role in biology as important as transistors in computers, and they use rather similar physics to perform part of that role. Understanding their fluctuations awaits physical insight into the source of the variance and mathematical analysis of the coupling of the fluctuations to the other components and forces of the system.Comment: Revised version of earlier submission, as invited, refereed, and published by journa

AI Risk Profiles: A Standards Proposal for Pre-Deployment AI Risk Disclosures

As AI systems' sophistication and proliferation have increased, awareness of the risks has grown proportionally (Sorkin et al. 2023). In response, calls have grown for stronger emphasis on disclosure and transparency in the AI industry (NTIA 2023; OpenAI 2023b), with proposals ranging from standardizing use of technical disclosures, like model cards (Mitchell et al. 2019), to yet-unspecified licensing regimes (Sindhu 2023). Since the AI value chain is complicated, with actors representing various expertise, perspectives, and values, it is crucial that consumers of a transparency disclosure be able to understand the risks of the AI system the disclosure concerns. In this paper we propose a risk profiling standard which can guide downstream decision-making, including triaging further risk assessment, informing procurement and deployment, and directing regulatory frameworks. The standard is built on our proposed taxonomy of AI risks, which reflects a high-level categorization of the wide variety of risks proposed in the literature. We outline the myriad data sources needed to construct informative Risk Profiles and propose a template-based methodology for collating risk information into a standard, yet flexible, structure. We apply this methodology to a number of prominent AI systems using publicly available information. To conclude, we discuss design decisions for the profiles and future work

Overlooked in the Tort Reform Debate: The Growth of Erroneous Removal

Disputes over forum often center on whether a case should proceed in state or federal court. Removal to federal court can trigger a costly forum struggle. When a state case is removed to federal court only to be sent back to state court, the time and resources incurred in the detour are a toll on the judicial system and waste parties’ resources. We find erroneous removal to be an increasing problem. From 1993 to 2002, a period when state tort filings noticeably decreased, the number of removed diversity tort cases increased by about 10 percent to about 8,900 per year. By 2003, removed cases comprised over 30 percent of the federal diversity docket. The percentage of removals ultimately remanded to state court increased significantly to about 20 percent in 2003, with the remand rate exceeding 50 percent in some districts. Thus, as more cases purporting to satisfy diversity jurisdiction were being removed to federal court, and just as removals were occupying an increasing part of the federal docket, removed cases were being remanded to state court at increasing rates. Erroneous removal is a growing phenomenon that should be addressed as part of serious consideration of tort reform

Promoting Healthcare Innovation on the Demand Side

Innovation policy often focuses on the incentives of firms that sell new products. But optimal use of healthcare products also requires good information about the likely effects of products in different patients, and it is hard to provide the right incentives for producers to develop and disclose information that could limit future sales. Regulation partially fills this gap by requiring sellers to conduct clinical trials and report adverse events. But it is inherently problematic to rely on producers to supply negative information about their own products. Healthcare payers, however, can profit from avoiding inappropriate use of costly technologies. Recent technological advances enable insurers to innovate by analyzing their data about healthcare provision and outcomes. The federal government seeks to promote this sort of innovation through a series of initiatives; some picture insurers as passive data repositories, while others provide opportunities for insurers to innovate more directly. In this paper, we examine the role of health insurers in developing new knowledge about the provision of quality healthcare—what we call “demand-side innovation.” We address the contours of this underexplored area of innovation and describe the behavior of participating firms. We examine the legal rules surrounding privacy and their effects on this research, and consider the effect of market structures and intellectual property rules on incentives for demand-side innovation. Throughout, we highlight the multi-pronged way that government facilitates payer innovation, apart from the traditional tools of innovation policy

Dual self-tuning parameter-robust minimax output regulation of a first-order process with ellipsoidal uncertainty

The parameters of a first-order process with known disturbance bounds are known to lie in an ellipsoidal region. At each sample, a static output feedback is designed which minimizes the maximum absolute output over the disturbance and parameter ranges. Then from the resulting measurements, the ellipsoid is updated according to a specific criterion. This criterion should be chosen for adequate performance of the resulting selftuning regulator. It is shown that a dual criterion minimizing a weighted sum of ellipsoidal volume and control performance outperforms these separate criteria

Description of nuclear octupole and quadrupole deformation close to the axial symmetry: Octupole vibrations in the X(5) nuclei 150Nd and 152Sm

The model, introduced in a previous paper, for the description of the octupole and quadrupole degrees of freedom in conditions close to the axial symmetry, is used to describe the negative-parity band based on the first octupole vibrational state in nuclei close to the critical point of the U(5) to SU(3) phase transition. The situation of 150Nd and 152Sm is discussed in detail. The positive parity levels of these nuclei, and also the in-band E2 transitions, are reasonably accounted for by the X(5) model. With simple assumptions on the nature of the octupole vibrations, it is possible to describe, with comparable accuracy, also the negative parity sector, without changing the description of the positive-parity part.Comment: 8 pages, 5 figure