Space Shuttle Main Engine Debris Testing Methodology and Impact Tolerances

In the wake of the Space Shuttle Columbia disaster every effort is being made to determine the susceptibility of Space Shuttle elements to debris impacts. Ice and frost debris is formed around the aft heat shield closure of the orbiter and liquid hydrogen feedlines. This debris has been observed to liberate upon lift-off of the shuttle and presents potentially dangerous conditions to the Space Shuttle Main Engine. This paper describes the testing done to determine the impact tolerance of the Space Shuttle Main Engine nozzle coolant tubes to ice strikes originating from the launch pad or other parts of the shuttle

Effect of Acute Antioxidant Consumption on Cardiac Baroreflex Sensitivity in Young Healthy Adults

There is an emerging body of evidence in animals indicating that elevated oxidative stress impairs baroreflex sensitivity (BRS) function, however studies in healthy humans have yielded equivocal results. One potential reason for this discrepancy is that previous studies have used individual antioxidant treatments (e.g., Vitamin C only) to investigate the effect of oxidative stress on BRS. Recent studies in healthy humans have demonstrated significant reductions in reactive oxygen species using an antioxidant cocktail (AOC; Vitamin C, Vitamin E, and Co-enzyme Q10) suggesting the effectiveness of this treatment. Whether this AOC induced reduction in oxidative species affects BRS in young, healthy adults remains unknown. PURPOSE: We tested the hypothesis that AOC will improve cardiac BRS in young healthy adults. METHODS: Five young men were studied on two separate days: placebo (sugar pills) and AOC (2000 mg Vitamin C, 150 IU Vitamin E and 100 mg Co-enzyme Q10) performed in random order. Resting heart rate (ECG) and arterial blood pressure (automated sphygmomanometer and finger photoplethysmography) were measured 90 minutes after AOC or placebo (a time period this AOC has been shown to have peak effects on oxidative stress). Spontaneous cardiac BRS was determined for all sequences combined (overall BRS), and also separately for up (increase systolic blood pressure: increase R-R interval) and down (decrease systolic blood pressure: decrease R-R interval) sequences. RESULTS: Systolic blood pressure on AOC day tended to be lower relative to the placebo day (127 ± 4 vs. 131 ± 5; p=0.098). However, no differences in overall cardiac BRS were found between placebo and AOC (18.0 ± 2.7 vs.17.3 ± 2.6 ms/mmHg; p=0.59). Likewise, up sequences (17.02 ± 2.9 vs 14.04 ± 4.0 ms/mmHg; p=0.51) and down sequences (18.0 ± 2.7 placebo vs. 18.0 ± 2.6 ms/mmHg AOC; p=0.98) were not different between conditions. Equal number of sequences were found between the placebo and AOC days. CONCLUSION: These preliminary data suggest that antioxidant treatment does not affect resting cardiac BRS in young, healthy men

Sympathetically-Mediated Cutaneous Vasoconstriction Is Similar Between Non-Hispanic Black and White Individuals

Cardiovascular disease (CVD) prevalence is highest in non-Hispanic Black (BL) individuals compared to any other race. The mechanisms responsible remain incompletely understood and can be impacted by several environmental, psychosocial, and socioeconomic factors. A major contributing factor to elevated CVD risk/prevalence in the BL population is altered vascular function, which could be attributed to an exaggerated vasoconstrictor response to efferent sympathetic activity (i.e., sympathetic vascular transduction). Previous data from our group demonstrates heightened sympathetic vascular transduction in the peripheral vasculature of BL males. However, whether sympathetically-mediated vasoconstriction is exaggerated in the cutaneous circulation of BL individuals remains unknown. PURPOSE: This study tested the hypothesis that BL individuals exhibit exaggerated vasoconstriction to intra-dermal infusions of the α-adrenoreceptor agonist norepinephrine (NE) relative to White (WH) individuals. METHODS: In this study, young, healthy college-aged BL (n=13; 6 females) and WH (n=10; 4 females) individuals participated. Participants were instrumented with an intradermal microdialysis membrane in the dorsal forearm. Red blood cell flux was continuously assessed via laser Doppler flowmetry before (baseline) and during incrementally stronger infusions of NE (10-8 M – 10-2 M; 6 min/dose). Data were analyzed as a relative (i.e., percent) reduction in cutaneous vascular conductance (CVC: flux/MAP) compared to the pre-infusion baseline. RESULTS: NE caused a dose-dependent reduction in CVC in both groups (P\u3c0.001). There was no difference between the BL and WH individuals (P=0.37) nor was there a race x dose interaction (P=0.84). Similarly, when the data were separated by sex there was no difference between BL and WH males (P=0.56) or females (P=0.26). CONCLUSION: Vasoconstrictor responsiveness to α-adrenoreceptor activation was similar between BL and WH individuals. These data suggest that the cutaneous circulation may exhibit divergent sympathically-mediated vasoconstrictor responsiveness relative to other peripheral vascular beds in BL individuals

When Programs Collide - A Panel Discussion on the Competing Interests of Analytics and Security

The increasing demand for business analytics and cybersecurity professionals provides an exciting job outlook for graduates of information systems programs. However, the rapid proliferation of devices and systems that has spurred this trend has created a challenging ethical dilemma for those responsible for educating future generations of IT professionals. Many firms are collecting and storing as much data as possible in the hopes that technology might uncover useful insights in the future. This results in an ever-increasing challenge for those charged with protecting organizational assets and exerts pressure on executives seeking an analytical edge to remain profitable in a hyper-competitive marketplace. With this dilemma in mind, the panel will search for a delicate balance between unleashing the power of analytics and securing the sensitive data it consumes. Keyword

Orion Handling Qualities During ISS Proximity Operations and Docking

NASA's Orion spacecraft is designed to autonomously rendezvous and dock with many vehicles including the International Space Station. However, the crew is able to assume manual control of the vehicle s attitude and flight path. In these instances, Orion must meet handling qualities requirements established by NASA. Two handling qualities assessments were conducted at the Johnson Space Center to evaluate preliminary designs of the vehicle using a six degree of freedom, high-fidelity guidance, navigation, and control simulation. The first assessed Orion s handling qualities during the last 20 ft before docking, and included both steady and oscillatory motions of the docking target. The second focused on manual acquisition of the docking axis during the proximity operations phase and subsequent station-keeping. Cooper-Harper handling qualities ratings, workload ratings and comments were provided by 10 evaluation pilots for the docking study and 5 evaluation pilots for the proximity operations study. For the docking task, both cases received 90% Level 1 (satisfactory) handling qualities ratings, exceeding NASA s requirement. All ratings for the ProxOps task were Level 1. These evaluations indicate that Orion is on course to meet NASA's handling quality requirements for ProxOps and docking

Dielectrophoresis based discrimination of human embryonic stem cells from differentiating derivatives

Assessment of the dielectrophoresis(DEP) cross-over frequency (f xo), cell diameter, and derivative membranecapacitance (C m) values for a group of undifferentiated human embryonic stem cell (hESC) lines (H1, H9, RCM1, RH1), and for a transgenic subclone of H1 (T8) revealed that hESC lines could not be discriminated on their mean f xo and C m values, the latter of which ranged from 14 to 20 mF/m2. Differentiation of H1 and H9 to a mesenchymal stem cell-like phenotype resulted in similar significant increases in mean C m values to 41–49 mF/m2 in both lines (p < 0.0001). BMP4-induced differentiation of RCM1 to a trophoblast cell-like phenotype also resulted in a distinct and significant increase in mean C m value to 28 mF/m2 (p < 0.0001). The progressive transition to a higher membranecapacitance was also evident after each passage of cell culture as H9 cells transitioned to a mesenchymal stem cell-like state induced by growth on a substrate of hyaluronan. These findings confirm the existence of distinctive parameters between undifferentiated and differentiating cells on which future application of dielectrophoresis in the context of hESC manufacturing can be based

Quadrupole Pairing Interaction and Signature Inversion

The signature inversion in the \pi h11/2 \otimes \nu h11/2 rotational bands of odd-odd Cs and La isotopes and the \pi h11/2 \otimes \nu i13/2 bands of odd-odd Tb, Ho and Tm nuclei is investigated using pairing and deformation self consistent mean field calculations. The model can rather satisfactorily account for the anomalous signature splitting, provided that spin assignments in som of the bands are revised. Our calculations show that signature inversioncan appear already at axially symmetric shapes. It is found that this is due to the contribution of the \lambda\mu=22 component of the quadrupole pairing interaction to the mean field potential.Comment: 17 pages, 14 figures, Nuclear Physics A in prin

Structure and Phase Transitions of the 6, 6-Cyclopropane Isomer of C_ {61} H_ {2}

We have used x-ray powder diffraction and differential scanning calorimetry to study the crystalline structures and thermal behavior of the 6,6-cyclopropane isomer of C61H2. At room temperature, the C61H2 cyclopropane molecules, like those of the 6,5-annulene isomer and C60O epoxide, are orientationally disordered and crystallize on a face-centered-cubic lattice such that their methylene groups are statistically disordered among the octahedral voids. Unlike 6,5−C61H2 and C60O, the low-temperature structure is not Pa3¯, but rather a low-symmetry orthorhombic lattice in which a≈

When Programs Collide: A Panel Report on the Competing Interests of Analytics and Security

The increasing demand for business analytics and cybersecurity professionals provides an exciting job outlook for graduates of information systems programs. However, the rapid proliferation of devices and systems that spurred this trend has created a challenging ethical dilemma for the individuals responsible for educating future generations of information technology professionals. Many firms collect and store as much data as possible in the hope that technology might uncover useful insights in the future. This behavior results in an ever-increasing challenge for those charged with protecting organizational assets and exerts pressure on executives seeking an analytical edge to remain profitable in a hyper-competitive marketplace. With this dilemma in mind, a recent panel discussion at the 14th Annual Midwest Association for Information Systems Conference explored the delicate balance between unleashing the power of analytics and securing the sensitive data it consumes while respecting consumer privacy. This paper reports on that discussion and its insights