The crystal structure of an Fe-superoxide dismutase from the hyperthermophile Aquifex pyrophilus at 1.9 A resolution: structural basis for thermostability

The incidence of stress fractures is increasing among competitive and recreational athletes as well as among children and the elderly. By understanding the continuum of bone's response to stress and maintaining an appropriate index of suspicion, the health care provider can diagnose these injuries appropriately. An accurate history and examination is essential and will differentiate stress fractures from other stress reactions. The more common stress fractures are discussed.     

Reliability and performance analysis of time – space – time switching networks with multiple separated space switches

Since electronic switching systems usually require very strict reliability requirements as well as good performance objectives, we need to jointly analyse the performance and reliability of switching systems. In this paper, we compare conventional time–space–time switches with single space switches with those with multiple separated space switches, from the viewpoints of reliability and performance. We consider time–space–time switching networks which consist of N incoming time switches, i.e. one NxN space switch, two (N/2)x(N/2) space switches, and four (N/4)x(N/4) space switches. We introduce a Markov reliability model to study the effect of failures and analyse the reliability and performance of three different types of switching networks in terms of average blocking probability and the mean time to unreliable operation, as we vary the offered traffic. As a result, T–S–T switching networks with multiple separated space switches exhibit better performance and reliability than those with single space switches.     

Analysis of composite laminates with transverse cracks

The analysis of the behaviour of composite laminates with general balanced lay-up sequences and containing distributed transverse cracks is discussed and demonstrated in this paper. It is shown that a constitutive model of damage for composites, which has been successfully used to analyse the effects of uniformly distributed transverse cracks in cross-ply laminates, can be readily extended to the analysis of uniformly distributed transverse cracks in more general symmetric laminates. The further extension of the theory to non-uniformly distributed damage can be achieved by finite element analysis. It is shown that the finite element implementation of the theory is particularly simple since the contribution of the damage to the overall behaviour can be incorporated into the force vectors.     

Influence of lips on thin-walled sections

Turning the free edge of an unstiffened flange inwards or outwards to form a ‘lip’, can substantially improve the local buckling resistance of a member. The lip is the most common type of edge stiffener used in cold-rolled, thin-walled sections. In this paper the behaviour of plate elements of thin-walled sections stiffened by compound lips (i.e. lips which are folded twice to form ‘lips on the lips’) is examined both theoretically and experimentally. An outline of a series of tests on compound edge-stiffened thin-walled sections of various geometries is given and some load-end compression displacement paths are compared with the theoretical predictions. Reasonably good agreement is obtained between the experimental and theoretical results. Comparisons of the theoretical predictions with experimental results of other researchers are also presented in this paper.     

Strong Diffie-Hellman-DSA Key Exchange

To provide authentication to the Diffie-Hellman key exchange, a few integrated key exchange schemes which provide authentication using the DSA signature have been proposed in the literature. In this letter we point out that all of the previous Diffie-Hellman-DSA schemes do not provide security against session state reveal attacks. We also suggest a strong Diffie-Hellman-DSA scheme providing security against session state reveal attacks as well as forward secrecy and key independence     

A novel phase noise reduction technique in oscillators usingdefected ground structure

A new technique to reduce the phase noise in microwave oscillators is developed using the resonant characteristic of the defected ground structure (DGS). Two kinds of oscillators have been designed and measured for the examination of the reduction of phase noise by the DGS. The first adopts the DGS section under the microstrip line at the gate circuit, while the second has only the conventional microstrip line. Measurement shows reduced phase noise by 10-15 dB in the oscillator with the DGS compared to the conventional one