EEG and field potential rhythms established in the cortex and thalamus may accommodate the propagation of seizures. This article describes the interaction between thalamus and cortex during pentylenetetrazol (PTZ) seizures in rats with and without prior treatment with ethosuximide (ESM), a well-known antiepileptic drug (AED) that raises the threshold for seizures, was given before PTZ. The AED was given before PTZ convulsant administration. We track this thalamo-cortical association with a novel measure we have called the cross-bicoherence gain, or BISCOH. This quantity allows us to measure the spectral coherence in a purely higher order spectralmethodology. BISCOH is able to track the formation of nonlinearities at specific frequencies in the recorded EEG. BISCOH showed a strong increase in low alpha wave harmonic generationat 10 and 12.5 Hz after ESM treatment (p < 0.02 and p < 0.007, respectively). Conventional coherence failed to show distinctive and significant changes in thalamo-cortical coupling after ESM treatment at those frequencies and instead showed changes at 5 Hz. This rise in cortical rhythms is evidence of harmonic generation or new frequency formation in the thalamo-cortical system withAED therapy. BISCOH could become a powerful tool in unraveling changes in coherence due to neuroelectric modulation resulting from drug treatment or electrical stimulation.

We consider an improved least square algorithm based on subspace rotations using Procrustes approximation. Robust estimation of the poles of a narrowband signal is achieved by reducing the bias of the estimates. The key idea is to consider the signal as a vector in multi-dimensional space, and to separate the “pure signal” and the noise into two mutually orthogonal components lying in different subspaces. Though the quality of the estimated signal is not much improved as compared to the conventional least square based subspace approaches, the advantage of using the proposed algorithm is the asymptotically unbiased nature of the estimates.

Internet connected organizations often employ an Internet firewall to mitigate risks of system penetration, data theft, data destruction, and other security breaches. Conventional Internet firewalls, however, impose an overly simple inside vs outside model of security that is incompatible with many business practices that require extending limited trust to external entities. The paper reports on our experience with an enhanced security firewall based on Domain and Type Enforcement (DTE), a strong but flexible form of access control. A DTE firewall provides several benefits. First, it runs application level proxies in restrictive domains, thereby increasing security, and runs network services such as HTTP and FTP under DTE controls, thereby reducing risks that network based attacks will compromise local resources. Second, a DTE firewall coordinates role based security policies that span networks by passing DTE security attributes between DTE clients and servers. These attributes allow security policies at the endpoints to be coordinated; such coordination adds defense in depth to the traditional firewall security perimeter: this permits safe exportation of normally risky services such as NFS. Finally, a DTE firewall interoperates with "non DTE" systems and associates DTE security attributes with these systems so their interaction with DTE clients or servers can be controlled. We describe the design of a prototype DTE firewall system and informally evaluate its security, compatibility, functionality, and performance.

Time series analysis applications of eigenstructure algorithms focus on temporal frequency estimation. The authors show that the ESPRIT algorithm can also be applied to simple phase delays for sinusoids. They show that a time delay data model can be rendered in the ESPRIT matrix pencil structure. The PRO-ESPRIT formulation can be then utilized to solve for phase delays among sinusoids. An application area for this algorithm is the estimation of short time delays for low frequency sinusoids comprising EEG (electroencephalographic) recordings derived from different neural sites during epileptic seizure activity.

Type enforcement is a table-oriented mandatory access control mechanism well-suited for confining applications and restricting information flows. Although both flexible and strong, type enforcement alone imposes significant administrative costs and has not been widely adopted. Domain and Type Enforcement (DTE) is an enhanced version of type enforcement designed to provide needed simplicity and compatibility. Two primary techniques distinguish DTE from simple type enforcement: DTE policies are expressed in a high-level language that includes file security attribute associations as well as other access control information; and during system execution, DTE file security attributes are maintained using a concise human-readable format in a runtime DTE policy database, thus removing the need for security-specific low-level data formats. Such formats are a major source of incompatibility for security-enhanced systems. A DTE UNIX prototype system has been implemented to evaluate these primary DTE concepts. This paper presents experiences gained and preliminary results indicating that DTE can provide cost effective security increases to UNIX systems while maintaining a high degree of compatibility with existing programs and media.>