Propellant material compatibility program and results

The effects of long-term (up to 10 years) contact of inert materials with earth-storable propellants were studied for the purpose of designing chemical propulsion system components that can be used for current as well as future planetary spacecraft. The primary experimental work, and results to date are reported. Investigations include the following propellants: hydrazine, hydrazine-hydrazine nitrate blends, monomethyl-hydrazine, and nitrogen tetroxide. Materials include: aluminum alloys, corrosion-resistant steels, and titanium alloys. More than 700 test specimen capsules were placed in long-term storage testing at 43 C in the special material compatibility facility. Material ratings relative to the 10-year requirement have been assigned

NASA Sample Return Missions: Recovery Operations

The Utah Test and Training Range (UTTR), southwest of Salt Lake City, Utah, is the site of all NASA unmanned sample return missions. To date these missions include the Genesis solar wind samples (2004) and Stardust cometary and interstellar dust samples (2006). NASAs OSIRIS-REx Mission will return its first asteroid sample at UTTR in 2023

Invariant Peano curves of expanding Thurston maps

We consider Thurston maps, i.e., branched covering maps $f\colon S^2\to S^2$ that are postcritically finite. In addition, we assume that $f$ is expanding in a suitable sense. It is shown that each sufficiently high iterate $F=f^n$ of $f$ is semi-conjugate to $z^d\colon S^1\to S^1$, where $d$ is equal to the degree of $F$. More precisely, for such an $F$ we construct a Peano curve $\gamma\colon S^1\to S^2$ (onto), such that $F\circ \gamma(z) = \gamma(z^d)$ (for all $z\in S^1$).Comment: 63 pages, 12 figure

Fuselage shell and cavity response measurements on a DC-9 test section

A series of fuselage shell and cavity response measurements conducted on a DC-9 aircraft test section are described. The objectives of these measurements were to define the shell and cavity model characteristics of the fuselage, understand the structural-acoustic coupling characteristics of the fuselage, and measure the response of the fuselage to different types of acoustic and vibration excitation. The fuselage was excited with several combinations of acoustic and mechanical sources using interior and exterior loudspeakers and shakers, and the response to these inputs was measured with arrays of microphones and accelerometers. The data were analyzed to generate spatial plots of the shell acceleration and cabin acoustic pressure field, and corresponding acceleration and pressure wavenumber maps. Analysis and interpretation of the spatial plots and wavenumber maps provided the required information on modal characteristics, structural-acoustic coupling, and fuselage response

Scalable Task-Based Algorithm for Multiplication of Block-Rank-Sparse Matrices

A task-based formulation of Scalable Universal Matrix Multiplication Algorithm (SUMMA), a popular algorithm for matrix multiplication (MM), is applied to the multiplication of hierarchy-free, rank-structured matrices that appear in the domain of quantum chemistry (QC). The novel features of our formulation are: (1) concurrent scheduling of multiple SUMMA iterations, and (2) fine-grained task-based composition. These features make it tolerant of the load imbalance due to the irregular matrix structure and eliminate all artifactual sources of global synchronization.Scalability of iterative computation of square-root inverse of block-rank-sparse QC matrices is demonstrated; for full-rank (dense) matrices the performance of our SUMMA formulation usually exceeds that of the state-of-the-art dense MM implementations (ScaLAPACK and Cyclops Tensor Framework).Comment: 8 pages, 6 figures, accepted to IA3 2015. arXiv admin note: text overlap with arXiv:1504.0504

Increased risk for other cancers in individuals with Ewing sarcoma and their relatives.

BackgroundThere are few reports of the association of other cancers with Ewing sarcoma in patients and their relatives. We use a resource combining statewide genealogy and cancer reporting to provide unbiased risks.MethodsUsing a combined genealogy of 2.3 million Utah individuals and the Utah Cancer Registry (UCR), relative risks (RRs) for cancers of other sites were estimated in 143 Ewing sarcoma patients using a Cox proportional hazards model with matched controls; however, risks in relatives were estimated using internal cohort-specific cancer rates in first-, second-, and third-degree relatives.ResultsCancers of three sites (breast, brain, complex genotype/karyotype sarcoma) were observed in excess in Ewing sarcoma patients. No Ewing sarcoma patients were identified among first-, second-, or third-degree relatives of Ewing sarcoma patients. Significantly increased risk for brain, lung/bronchus, female genital, and prostate cancer was observed in first-degree relatives. Significantly increased risks were observed in second-degree relatives for breast cancer, nonmelanoma eye cancer, malignant peripheral nerve sheath cancer, non-Hodgkin lymphoma, and translocation sarcomas. Significantly increased risks for stomach cancer, prostate cancer, and acute lymphocytic leukemia were observed in third-degree relatives.ConclusionsThis analysis of risk for cancer among Ewing sarcoma patients and their relatives indicates evidence for some increased cancer predisposition in this population which can be used to individualize consideration of potential treatment of patients and screening of patients and relatives

Midlife Women's Responses to a Hospital Sleep Challenge: Aging and Menopause Effects on Sleep Architecture

Objective: To distinguish aging from menopause effects on sleep architecture, we studied an episode of disturbed hospital sleep in asymptomatic midlife women during the follicular phase of an ovulatory cycle and three control groups differing by age or menopause status. Methods: Fifty-one studies were conducted in four groups of volunteers: young cycling (YC, 20-30 years, n = 14), older cycling (OC, 40-50 years, n = 15), ovariectomized receiving estrogen therapy (OVX, 40-50 years, n = 12), and spontaneously postmenopausal (PM, 40-50 years, n = 10). Subjects were admitted to the University Hospital General Clinical Research Center (GCRC) for a first-night sleep study conducted during a 24-hour, frequent blood sampling protocol. Results: Despite similar estrogen concentrations in the YC (28 ± 4 pg/ml) and OC (34 ± 6 pg/ml) groups, OC women had reduced sleep efficiency (79% ± 2%) vs. YC (87% ± 3%; p = 0.009). In the OVX and PM groups where estrogen concentrations were markedly different, sleep efficiency was also reduced vs. the YC group (OVX vs. YC, 79% ± 3% vs. 87% ± 3%, p = 0.05; PM vs. YC, 75% ± 3% vs. 87% ± 3%, p = 0.007). Wake time was longer in the three older groups (103 ± 10 minutes, 101 ± 12 minutes, 123 ± 12 minutes for OC, OVX, PM, respectively) vs. YC (63 ± 13 minutes, p < 0.05). The number of stage shifts was positively associated with advancing age (rho = 0.3, p < 0.03) but not with estrogen concentration. Conclusions: Aging-related sleep deficits in response to an experimental stressor occur in midlife women prior to menopause.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63173/1/154099904323016491.pd

Stochastic Feedback and the Regulation of Biological Rhythms

We propose a general approach to the question of how biological rhythms spontaneously self-regulate, based on the concept of ``stochastic feedback''. We illustrate this approach by considering the neuroautonomic regulation of the heart rate. The model generates complex dynamics and successfully accounts for key characteristics of cardiac variability, including the $1/f$ power spectrum, the functional form and scaling of the distribution of variations, and correlations in the Fourier phases. Our results suggest that in healthy systems the control mechanisms operate to drive the system away from extreme values while not allowing it to settle down to a constant output.Comment: 15 pages, latex2e using rotate and epsf, with 4 ps figures. Submitted to PR