System overview of the NASA Dryden Integrated Test Facility

The Integrated Test Facility, built at the NASA Dryden Flight Research Facility, provides new real-time test capabilities for emerging research aircraft. An overview of the test facility and the real-time systems developed to operate this unique facility is presented. The facility will reduce flight test risk by minimizing the difference between the flight and ground test environments. This ground test environment is provided by combining real-time flight simulation with the actual aircraft. A brief introduction to the facility is followed by a discussion of the generic capabilities of its real-time systems. The simulation system with flight hardware and the remotely augmented vehicle system is described. An overview of many hardware systems developed for the facility follows. The benefits of applying simulation to hardware-in-the-loop testing on the X-31 Flight Research Program are presented

Optic Disc Drusen Resulting in Disqualifying Field Loss

Background: Optic nerve (or disc) drusen is the presence of hyaline bodies at the optic nerve head. The drusen may be visible upon funduscopic examination or may present as buried. Timely diagnosis and responsible imaging may help inform the patient of the potential for future concerns. The long-term prognosis is good for most patients, however, they may experience progressive peripheral vision loss that may reduce the patient’s quality of life. Neuroprotective options have previously been discussed with minimal clinical effectiveness, however, new medications may aid in future treatment. Case Report: A patient presenting with mild and slowly progressing vision loss was examined and found to have optic disc drusen. Visual fields were done to quantify the extent of vision loss and revealed the patient no longer met the criteria for his commercial driver’s license. Findings, imaging, and treatment options are discussed. Conclusion: While no effective treatments exist currently, the potential benefit of brimonidine as a neuroprotective agent is discussed along with other future potential options. An assessment of the viability of the patient’s cost benefit ratio is discussed

Herpetic Keratitis, Patience is a Virtue: HSK in Immunocompromised Patient

Background: The Herpes virus is ubiquitous in our patient population. Often it is present without symptoms, however, it may present with pain, irritation, and decreased vision. In high-risk populations a longer course of treatment is often required. Case Report: This case report will detail the treatment options and outcome in a patient with herpes keratitis who also is HIV positive and addresses concerns about treating immunocompromised patients. Conclusion: This case serves as a review of common and uncommon treatment options for herpes keratitis as well as a review of potential causes of this presentation. Herpetic keratitis is likely to be something most providers will encounter during their careers. Use of oral antivirals is often more cost effect, better tolerated, and improves compliance

Pupil involving oculomotor palsy- Examination, Cause and Outcome

BACKGROUND: A patient with a third cranial nerve (CN III) palsy can be a stress inducing event for an optometrist due to the potentially life-threatening etiologies and infrequency of their presentation. The pathogenesis of a CN III palsy can vary from innocuous to life threatening. Palsy of the third cranial nerve results in an impairment of eye movement and / or pupillary response to light depending on the extent of the palsy. CASE REPORT: This case reviews a recent onset of a complete right oculomotor palsy. Literature of similar cases detail the likelihood of variable causes, and while a diagnostic work-up is indicated based on the risk, the etiology of the palsy in this case was determined to be more benign in nature. CONCLUSION: Large scale population studies in the literature reveal the etiology of a CN III palsy from life-threatening conditions is lower than indicated based on published case reports. However, a complete evaluation of a patient including neuro-imagining is still warranted due to the potential life-threatening complications. Further population studies with increased diversity need to be performed to advance knowledge in this area

Decidability of strong equivalence for subschemas of a class of linear, free, near-liberal program schemas

The article attached is a preprint version of the final published article which can be accessed at the link below. The article title has been changed. For referencing purposes please use the published details. Copyright © 2010 Elsevier B.V. All rights reserved.A program schema defines a class of programs, all of which have identical statement structure, but whose functions and predicates may differ. A schema thus defines an entire class of programs according to how its symbols are interpreted. Two schemas are strongly equivalent if they always define the same function from initial states to final states for every interpretation. A subschema of a schema is obtained from a schema by deleting some of its statements. A schema S is liberal if there exists an initial state in the Herbrand domain such that the same term is not generated more than once along any executable path through S. In this paper, we introduce near-liberal schemas, in which this non-repeating condition applies only to terms not having the form g() for a constant function symbol g. Given a schema S that is linear (no function or predicate symbol occurs more than once in S) and a variable v, we compute a set of function and predicate symbols in S which is a subset of those defined by Weiser's slicing algorithm and prove that if for every while predicate q in S and every constant assignment w:=g(); lying in the body of q, no other assignment to w also lies in the body of q, our smaller symbol set defines a correct subschema of S with respect to the final value of v after execution. We also prove that if S is also free (every path through S is executable) and near-liberal, it is decidable which of its subschemas are strongly equivalent to S. For the class of pairs of schemas in which one schema is a subschema of the other, this generalises a recent result in which S was required to be linear, free and liberal.This work was supported by a grant from the Engineering and Physical Sciences Research Council, Grant EP/E002919/1

A trajectory-based strict semantics for program slicing

We define a program semantics that is preserved by dependence-based slicing algorithms. It is a natural extension, to non-terminating programs, of the semantics introduced by Weiser (which only considered terminating ones) and, as such, is an accurate characterisation of the semantic relationship between a program and the slice produced by these algorithms. Unlike other approaches, apart from Weiser’s original one, it is based on strict standard semantics which models the ‘normal’ execution of programs on a von Neumann machine and, thus, has the advantage of being intuitive. This is essential since one of the main applications of slicing is program comprehension. Although our semantics handles non-termination, it is defined wholly in terms of finite trajectories, without having to resort to complex, counter-intuitive, non-standard models of computation. As well as being simpler, unlike other approaches to this problem, our semantics is substitutive. Substitutivity is an important property becauseit greatly enhances the ability to reason about correctness of meaning-preserving program transformations such as slicing

Characterizing minimal semantics-preserving slices of predicate-linear, free, liberal program schemas

This is a preprint version of the article - Copyright @ 2011 ElsevierA program schema defines a class of programs, all of which have identical statement structure, but whose functions and predicates may differ. A schema thus defines an entire class of programs according to how its symbols are interpreted. A subschema of a schema is obtained from a schema by deleting some of its statements. We prove that given a schema S which is predicate-linear, free and liberal, such that the true and false parts of every if predicate satisfy a simple additional condition, and a slicing criterion defined by the final value of a given variable after execution of any program defined by S, the minimal subschema of S which respects this slicing criterion contains all the function and predicate symbols ‘needed’ by the variable according to the data dependence and control dependence relations used in program slicing, which is the symbol set given by Weiser’s static slicing algorithm. Thus this algorithm gives predicate-minimal slices for classes of programs represented by schemas satisfying our set of conditions. We also give an example to show that the corresponding result with respect to the slicing criterion defined by termination behaviour is incorrect. This complements a result by the authors in which S was required to be function-linear, instead of predicate-linear.This work was supported by a grant from the Engineering and Physical Sciences Research Council, Grant EP/E002919/1