General purpose simulation system of the data management system for space shuttle mission 18

The simulation program of the science and engineering data management system for the space shuttle is presented. The programming language used was General Purpose Simulation System V (OS). The data flow was modeled from its origin at the experiments or subsystems to transmission from the space shuttle. Mission 18 was the particular flight chosen for simulation. First, the general structure of the program is presented and the trade studies which were performed are identified. Inputs required to make runs are discussed followed by identification of the output statistics. Some areas for model modifications are pointed out. A detailed model configuration, program listing and results are included

General purpose simulation system of the data management system for Space Shuttle mission 18

A simulation program for the flow of data through the Data Management System of Spacelab and Space Shuttle was presented. The science, engineering, command and guidance, navigation and control data were included. The programming language used was General Purpose Simulation System V (OS). The science and engineering data flow was modeled from its origin at the experiments and subsystems to transmission from Space Shuttle. Command data flow was modeled from the point of reception onboard and from the CDMS Control Panel to the experiments and subsystems. The GN&C data flow model handled data between the General Purpose Computer and the experiments and subsystems. Mission 18 was the particular flight chosen for simulation. The general structure of the program is presented, followed by a user's manual. Input data required to make runs are discussed followed by identification of the output statistics. The appendices contain a detailed model configuration, program listing and results

Career Paths in Educational Leadership: Examining Principals’ Narratives

This qualitative study analyzes the career path narratives of active principals. Structural narrative analysis was supplemented with sociolinguistic theory and thematic narrative analysis to discern the similarities and differences, as well as the patterns in the language used by participating principals. Thematic analysis found four major themes in the narratives: (1) passion for teaching and education; (2) external motivation to become a principal; (3) importance of the experience as an assistant principal; and (4) recent changes in the principalship. While all of the participants acknowledged difficulties associated with the principalship, the findings revealed differences between male and female leaders’ narratives in terms of structure, content, and style as well as certain similarities.Cette étude qualitative analyse les récits de directeurs d’école intérimaires par rapport à leur cheminement professionnel. Nous avons eu recours à une analyse narrative structurale, complétée par la théorie sociolinguistique et une analyse narrative thématique, pour examiner les patrons, les similarités et les différences linguistiques chez les directeurs et les directrices qui ont participé. L’analyse thématique a identifié quatre thèmes majeurs dans les récits : (1) une passion pour l’enseignement et l’éducation; (2) une motivation externe à devenir directeur d’école; (3) l’importance de l’expérience de directeur adjoint; et (4) des changements récents dans le rôle de directeur. Tous les participants ont reconnu des difficultés liées au rôle de directeur d’école, mais la structure, le contenu et le style des récits des hommes étaient différents de ceux des femmes. Notons que tous les récits partagaient quand même certaines similarités

Correction to note on linkage data for new ser mutants in NN #21

Correction to note on linkage data for new ser mutants in NN #2

Linkage data on two new swine-requiring mutants, one of which is a new locus, serine-5 (ser-5)

Linkage data on new ser mutants; new locus, ser-

The SPICE carbon isotope excursion in Siberia: a combined study of the upper Middle Cambrian-lowermost Ordovician Kulyumbe River section, northwestern Siberian Platform

An integrated, high-resolution chemostratigraphic (C, O and Sr isotopes) and magnetostratigraphic study through the upper Middle Cambrian–lowermost Ordovician shallowmarine carbonates of the northwestern margin of the Siberian Platform is reported. The interval was analysed at the Kulyumbe section, which is exposed along the Kulyumbe River, an eastern tributary of the Enisej River. It comprises the upper Ust’-Brus, Labaz, Orakta, Kulyumbe, Ujgur and lower Iltyk formations and includes the Steptoean positive carbon isotopic excursion (SPICE) studied here in detail from upper Cambrian carbonates of the Siberian Platform for the first time. The peak of the excursion, showing δ13C positive values as high as+4.6‰and least-altered 87Sr/86Sr ratios of 0.70909, is reported herein from the Yurakhian Horizon of the Kulyumbe Formation. The stratigraphic position of the SPICE excursion does not support traditional correlation of the boundary between theOrakta and Labaz formations at the Kulyumbe River with its supposedly equivalent level in Australia, Laurentia, South China and Kazakhstan, where the Glyptagnostus stolidotus and G. reticulatus biozones are known to immediately precede the SPICE excursion and span the Middle–Upper Cambrian boundary. The Cambrian–Ordovician boundary is probably situated in the middle Nyajan Horizon of the Iltyk Formation, in which carbon isotope values show a local maximum below a decrease in the upper part of the Nyajan Horizon, attributed herein to the Tremadocian Stage. A refined magnetic polarity sequence confirms that the geomagnetic reversal frequency was very high during Middle Cambrian times at 7–10 reversals per Ma, assuming a total duration of about 10 Ma and up to 100 magnetic intervals in the Middle Cambrian. By contrast, the sequence attributed herein to the Upper Cambrian on chemostratigraphic grounds contains only 10–11 magnetic intervals

Refinement Types for Secure Implementations

We present the design and implementation of a typechecker for verifying security properties of the source code of cryptographic protocols and access control mechanisms. The underlying type theory is a λ-calculus equipped with refinement types for expressing pre- and post-conditions within first-order logic. We derive formal cryptographic primitives and represent active adversaries within the type theory. Well-typed programs enjoy assertion-based security properties, with respect to a realistic threat model including key compromise. The implementation amounts to an enhanced typechecker for the general purpose functional language F#; typechecking generates verification conditions that are passed to an SMT solver. We describe a series of checked examples. This is the first tool to verify authentication properties of cryptographic protocols by typechecking their source code. © 2008 IEEE

Safe abstractions of data encodings in formal security protocol models

When using formal methods, security protocols are usually modeled at a high level of abstraction. In particular, data encoding and decoding transformations are often abstracted away. However, if no assumptions at all are made on the behavior of such transformations, they could trivially lead to security faults, for example leaking secrets or breaking freshness by collapsing nonces into constants. In order to address this issue, this paper formally states sufficient conditions, checkable on sequential code, such that if an abstract protocol model is secure under a Dolev-Yao adversary, then a refined model, which takes into account a wide class of possible implementations of the encoding/decoding operations, is implied to be secure too under the same adversary model. The paper also indicates possible exploitations of this result in the context of methods based on formal model extraction from implementation code and of methods based on automated code generation from formally verified model

A transcription-dependent increase in miniature EPSC frequency accompanies late-phase plasticity in cultured hippocampal neurons

<p>Abstract</p> <p>Background</p> <p>The magnitude and longevity of synaptic activity-induced changes in synaptic efficacy is quantified by measuring evoked responses whose potentiation requires gene transcription to persist for more than 2-3 hours. While miniature EPSCs (mEPSCs) are also increased in amplitude and/or frequency during long-term potentiation (LTP), it is not known how long such changes persist or whether gene transcription is required.</p> <p>Results</p> <p>We use whole-cell patch clamp recordings from dissociated hippocampal cultures to characterise for the first time the persistence and transcription dependency of mEPSC upregulation during synaptic potentiation. The persistence of recurrent action potential bursting in these cultures is transcription-, translation- and NMDA receptor-dependent thus providing an accessible model for long-lasting plasticity. Blockade of GABA_A-receptors with bicuculline for 15 minutes induced action potential bursting in all neurons and was maintained in 50-60% of neurons for more than 6 hours. Throughout this period, the frequency but neither the amplitude of mEPSCs nor whole-cell AMPA currents was markedly increased. The transcription blocker actinomycin D abrogated, within 2 hours of burst induction, both action potential bursting and the increase in mEPSCs. Reversible blockade of action potentials during, but not after this 2 hour transcription period suppressed the increase in mEPSC frequency and the recovery of burst activity at a time point 6 hours after induction.</p> <p>Conclusion</p> <p>These results indicate that increased mEPSC frequency persists well beyond the 2 hour transcription-independent phase of plasticity in this model. This long-lasting mEPSC upregulation is transcription-dependent and requires ongoing action potential activity during the initial 2 hour period but not thereafter. Thus mEPSC upregulation may underlie the long term, transcription-dependent persistence of action potential bursting. This provides mechanistic insight to link gene candidates already identified by gene chip analysis to long lasting plasticity in this in vitro model.</p

An evaluation of the utility of routine laboratory monitoring of juvenile idiopathic arthritis (JIA) patients using non-steroidal anti-inflammatory drugs (NSAIDs): a retrospective review

<p>Abstract</p> <p>Background</p> <p>No consensus evidence-based guidelines for the routine laboratory monitoring of children with JIA receiving non-steroidal anti-inflammatory drugs (NSAIDs) exist. The purpose of this study is to evaluate the clinical utility of routine laboratory monitoring of hemoglobin, transaminases, blood urea nitrogen, serum creatinine, and urinalysis in patients with juvenile idiopathic arthritis (JIA) receiving NSAIDs.</p> <p>Methods</p> <p>The medical records of 91 children with JIA followed between 1996 and 2006 were retrospectively reviewed for laboratory results and clinically significant adverse effects attributed to NSAID use. Laboratory abnormalities were documented, with potential adverse clinical sequelae, including if NSAID use was discontinued.</p> <p>Results</p> <p>Abnormal laboratory results were recorded for 24 of 91 patients. Nearly all abnormalities were mild and not associated with adverse clinical sequelae. All patients but one continued to receive NSAID therapy after the abnormality was detected.</p> <p>Conclusions</p> <p>Although detection of abnormal laboratory values occurred while on NSAIDs, these abnormalities did not correlate with adverse clinical signs and symptoms. The routine monitoring of laboratory tests in asymptomatic children treated with NSAIDs is of questionable utility.</p