Potential use of nutritional factors to optimize performance under stress

A study of the effects of amino acids on hypothalamo-pituitary capacity to secrete ACTH, and the response of the adrenal gland in terms of corticosterone level in the plasma was discussed in the first part of this report. Second, the report includes a study of the response of protein metabolism in various levels of corticosterone elevation in the plasma. This second part is regarded as having considerable significance for space travel, since this data indicate a threshold level of plasma corticosteroids above which there is increased catabolism of muscle protein

Simulation evaluation of a low-altitude helicopter flight guidance system adapted for a helmet-mounted display

A computer aiding concept for low-altitude helicopter flight was developed and evaluated in a real-time piloted simulation. The concept included an optimal control trajectory-generation algorithm based upon dynamic programming and a helmet-mounted display (HMD) presentation of a pathway-in-the-sky, a phantom aircraft, and flight-path vector/predictor guidance symbology. The trajectory-generation algorithm uses knowledge of the global mission requirements, a digital terrain map, aircraft performance capabilities, and advanced navigation information to determine a trajectory between mission way points that seeks valleys to minimize threat exposure. The pilot evaluation was conducted at NASA ARC moving base Vertical Motion Simulator (VMS) by pilots representing NASA, the U.S. Army, the Air Force, and the helicopter industry. The pilots manually tracked the trajectory generated by the algorithm utilizing the HMD symbology. The pilots were able to satisfactorily perform the tracking tasks while maintaining a high degree of awareness of the outside world

Entanglement generation in persistent current qubits

In this paper we investigate the generation of entanglement between two persistent current qubits. The qubits are coupled inductively to each other and to a common bias field, which is used to control the qubit behaviour and is represented schematically by a linear oscillator mode. We consider the use of classical and quantum representations for the qubit control fields and how fluctuations in the control fields tend to suppress entanglement. In particular, we demonstrate how fluctuations in the bias fields affect the entanglement generated between persistent current qubits and may limit the ability to design practical systems.Comment: 7 pages, 4 figures, minor changes in reply to referees comment

High Temperature Macroscopic Entanglement

In this paper I intend to show that macroscopic entanglement is possible at high temperatures. I analyze multipartite entanglement produced by the $\eta$ pairing mechanism which features strongly in the fermionic lattice models of high $T_c$ superconductivity. This problem is shown to be equivalent to calculating multipartite entanglement in totally symmetric states of qubits. I demonstrate that we can conclusively calculate the relative entropy of entanglement within any subset of qubits in an overall symmetric state. Three main results then follow. First, I show that the condition for superconductivity, namely the existence of the off diagonal long range order (ODLRO), is not dependent on two-site entanglement, but on just classical correlations as the sites become more and more distant. Secondly, the entanglement that does survive in the thermodynamical limit is the entanglement of the total lattice and, at half filling, it scales with the log of the number of sites. It is this entanglement that will exist at temperatures below the superconducting critical temperature, which can currently be as high as 160 Kelvin. Thirdly, I prove that a complete mixture of symmetric states does not contain any entanglement in the macroscopic limit. On the other hand, the same mixture of symmetric states possesses the same two qubit entanglement features as the pure states involved, in the sense that the mixing does not destroy entanglement for finite number of qubits, albeit it does decrease it. Maximal mixing of symmetric states also does not destroy ODLRO and classical correlations. I discuss various other inequalities between different entanglements as well as generalizations to the subsystems of any dimensionality (i.e. higher than spin half).Comment: 14 pages, no figure

Low Cost and Compact Quantum Cryptography

We present the design of a novel free-space quantum cryptography system, complete with purpose-built software, that can operate in daylight conditions. The transmitter and receiver modules are built using inexpensive off-the-shelf components. Both modules are compact allowing the generation of renewed shared secrets on demand over a short range of a few metres. An analysis of the software is shown as well as results of error rates and therefore shared secret yields at varying background light levels. As the system is designed to eventually work in short-range consumer applications, we also present a use scenario where the consumer can regularly 'top up' a store of secrets for use in a variety of one-time-pad and authentication protocols.Comment: 18 pages, 9 figures, to be published in New Journal of Physic

An evaluation of the appropriateness of advice and healthcare contacts made following calls to NHS Direct Wales

Background: An evaluation of NHS Direct Wales (NHSDW), a national telephone-based healthcare advice and information service, was undertaken. A key objective was to describe the actions of callers and assess the appropriateness of advice and healthcare contacts made following calls, results of which are reported here. Methods: Postal questionnaires were sent to consecutive callers to NHSDW in May 2002 and February 2004 to determine 1) callers' actions following calls and 2) their views about the appropriateness of: advice given; and when to seek further care. An independent clinical panel agreed and applied a set of rules about healthcare sites where examinations, investigations, treatments and referrals could be obtained. The rules were then applied to the subsequent contacts to healthcare services reported by respondents and actions were classified in terms of whether they had been necessary and sufficient for the care received. Results: Response rates were similar in each survey: 1033/1897 (54.5%); 606/1204 (50.3%), with 75% reporting contacting NHSDW. In both surveys, nearly half of all callers reported making no further healthcare contact after their call to NHSDW. The most frequent subsequent contacts made were with GPs. More than four fifths of callers rated the advice given - concerning any further care needed and when to seek it - as appropriate (further care needed: survey 1: 673/729, 82.3%; survey 2: 389/421, 92.4%; when to seek further care - survey 1: 462/555, 83.2%; survey 2: n = 295/346, 85.3%). A similar proportion of cases was also rated through the rule set and backed up by the clinical panel as having taken necessary and sufficient actions following their calls to NHSDW (survey 1: 624/729, 80.6%; survey 2: 362/421, 84.4%), with more unnecessary than insufficient actions identified at each survey (survey 1: unnecessary 132/729, 17.1% versus insufficient 11/729, 1.4%; survey 2: unnecessary 47/421, 11.0% versus insufficient 14/421, 3.3%). Conclusion: Based on NHSDW caller surveys responses and applying a transparent rule set to caller actions a large majority of subsequent actions were assessed as appropriate, with insufficient contacts particularly infrequent. The challenge for NHSDW is to reduce the number of unnecessary contacts made following calls to the service, whilst maintaining safety.</p