730 research outputs found
On the excitation of inertial modes in an experimental spherical Couette flow
Spherical Couette flow (flow between concentric rotating spheres) is one of
flows under consideration for the laboratory magnetic dynamos. Recent
experiments have shown that such flows may excite Coriolis restored inertial
modes. The present work aims to better understand the properties of the
observed modes and the nature of their excitation. Using numerical solutions
describing forced inertial modes of a uniformly rotating fluid inside a
spherical shell, we first identify the observed oscillations of the Couette
flow with non-axisymmetric, retrograde, equatorially anti-symmetric inertial
modes, confirming first attempts using a full sphere model. Although the model
has no differential rotation, identification is possible because a large
fraction of the fluid in a spherical Couette flow rotates rigidly. From the
observed sequence of the excited modes appearing when the inner sphere is
slowed down by step, we identify a critical Rossby number associated with a
given mode and below which it is excited. The matching between this critical
number and the one derived from the phase velocity of the numerically computed
modes shows that these modes are excited by an instability likely driven by the
critical layer that develops in the shear layer staying along the tangent
cylinder of the inner sphere.Comment: 11 pages, 17 figure
Idasanutlin and navitoclax induce synergistic apoptotic cell death in T-cell acute lymphoblastic leukemia
T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematologic malignancy in which activating mutations in the Notch pathway are thought to contribute to transformation, in part, by activating c-Myc. Increased c-Myc expression induces oncogenic stress that can trigger apoptosis through the MDM2-p53 tumor suppressor pathway. Since the great majority of T-ALL cases carry inactivating mutations upstream in this pathway but maintain wildtype MDM2 and TP53, we hypothesized that T-ALL would be selectively sensitive to MDM2 inhibition. Treatment with idasanutlin, an MDM2 inhibitor, induced only modest apoptosis in T-ALL cells but upregulated the pro-apoptotic BH3 domain genes BAX and BBC3, prompting us to evaluate the combination of idasanutlin with BH3 mimetics. Combination treatment with idasanutlin and navitoclax, a potent Bcl-2/Bcl-xL inhibitor, induces more consistent and potent synergistic killing of T-ALL PDX lines in vitro than venetoclax, a Bcl-2 specific inhibitor. Moreover, a marked synergic response to combination treatment with idasanutlin and navitoclax was seen in vivo in all four T-ALL xenografts tested, with a significant increase in overall survival in the combination treatment group. Collectively, these preclinical data show that the combination of idasanutlin and navitoclax is highly active in T-ALL and may merit consideration in the clinical setting
Survival rates of band‐tailed pigeons estimated using passive integrated transponder tags
Obtaining survival estimates on the Interior population of band-tailed pigeons (Patagioenas fasciata) is challenging because they are trap shy, but the joint use of passive integrated transponder (PIT) tags and bands is a potential solution. We investigated the use of PIT tags to passively recapture band‐tailed pigeon at 3 locations in New Mexico, USA, to estimate survival. From 2013–2015, we captured, banded, and marked \u3e600 individual band‐tailed pigeons with PIT tags. To estimate annual survival rates, we used a Barker multi‐state joint live and dead encounters and resighting model. Survival models excluding transience had survival estimates across site, sex, and year of 0.86 (95% CI = 0.84–0.88) for after hatch year birds and 0.63 (95% CI = 0.48–0.76) for hatch year birds. These results are consistent with other survival estimates reported for the Interior population of band‐tailed pigeons using band return data and potentially provide an effective alternative method of monitoring survival of this population
Face-Sheet Quality Analysis and Thermo-Physical Property Characterization of OOA and Autoclave Panels
Increased application of polymer matrix composite (PMC) materials in large vehicle structures requires consideration of non-autoclave manufacturing technology. The NASA Composites for Exploration project, and its predecessor, Lightweight Spacecraft Structures and Materials project, were tasked with the development of materials and manufacturing processes for structures that will perform in a heavy-lift-launch vehicle environment. Both autoclave and out of autoclave processable materials were considered. Large PMC structures envisioned for such a vehicle included the payload shroud and the interstage connector. In this study, composite sandwich panels representing 1/16th segments of the barrel section of the Ares V rocket fairing were prepared as 1.8 m x 2.4 m sections of the 10 m diameter arc segment. IM7/977-3 was used as the face-sheet prepreg of the autoclave processed panels and T40-800B/5320-1 for the out of autoclave panels. The core was 49.7 kilograms per square meters (3.1 pounds per cubic feet (pcf)) aluminum honeycomb. Face-sheets were fabricated by automated tape laying 153 mm wide unidirectional tape. This work details analysis of the manufactured panels where face-sheet quality was characterized by optical microscopy, cured ply thickness measurements, acid digestion, and thermal analysis
Assessing the Total Effect of Time-Varying Predictors in Prevention Research
Observational data are often used to address prevention questions such as, “If alcohol initiation could be delayed, would that in turn cause a delay in marijuana initiation?” This question is concerned with the total causal effect of the timing of alcohol initiation on the timing of marijuana initiation. Unfortunately, when observational data are used to address a question such as the above, alternative explanations for the observed relationship between the predictor, here timing of alcohol initiation, and the response abound. These alternative explanations are due to the presence of confounders. Adjusting for confounders when using observational data is a particularly challenging problem when the predictor and confounders are time-varying. When time-varying confounders are present, the standard method of adjusting for confounders may fail to reduce bias and indeed can increase bias. In this paper, an intuitive and accessible graphical approach is used to illustrate how the standard method of controlling for confounders may result in biased total causal effect estimates. The graphical approach also provides an intuitive justification for an alternate method proposed by James Robins [Robins, J. M. (1998). 1997 Proceedings of the American Statistical Association, section on Bayesian statistical science (pp. 1–10). Retrieved from http://www.biostat.harvard.edu/robins/research.html; Robins, J. M., Hernán, M., & Brumback, B. (2000). Epidemiology, 11 (5), 550–560]. The above two methods are illustrated by addressing the motivating question. Implications for prevention researchers who wish to estimate total causal effects using longitudinal observational data are discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45504/1/11121_2005_Article_23.pd
Report of Second Meeting for the Purpose of Obtaining the Views of the Three Affiliated Tribes of the Fort Berthold Reservation on the Lieu Lands Offered by the Secretary of War, 1946
Report of the second meeting held in the office of Assistant Secretary of the Interior C. Girard Davidson for the purpose of obtaining the views of the Three Affiliated Tribes of the Fort Berthold Reservation of the lieu lands offered by the Secretary of War. Includes a list of attendees and a transcript of the meeting discussing the Three Affiliated Tribes\u27 rejection of the offer of lieu lands made by the Secretary of Interior and Department of War to the Fort Berthold Reservation.
See also:
Report of Meeting for the Purpose of Obtaining the Views of the Three Affiliated Tribes of the Fort Berthold Reservation on the Lieu Lands Offered by the Secretary of War, 1946https://commons.und.edu/langer-papers/1147/thumbnail.jp
Recommended Priorities for Research on Ecological Impacts of Ocean and Coastal Acidification in the U.S. Mid-Atlantic
The estuaries and continental shelf system of the United States Mid-Atlantic are subject to ocean acidification driven by atmospheric CO2, and coastal acidification caused by nearshore and land-sea interactions that include biological, chemical, and physical processes. These processes include freshwater and nutrient input from rivers and groundwater; tidally-driven outwelling of nutrients, inorganic carbon, alkalinity; high productivity and respiration; and hypoxia. Hence, these complex dynamic systems exhibit substantial daily, seasonal, and interannual variability that is not well captured by current acidification research on Mid-Atlantic organisms and ecosystems. We present recommendations for research priorities that target better understanding of the ecological impacts of acidification in the U. S. Mid-Atlantic region. Suggested priorities are: 1) Determining the impact of multiple stressors on our resource species as well as the magnitude of acidification; 2) Filling information gaps on major taxa and regionally important species in different life stages to improve understanding of their response to variable temporal scales and sources of acidification; 3) Improving experimental approaches to incorporate realistic environmental variability and gradients, include interactions with other environmental stressors, increase transferability to other systems or organisms, and evaluate community and ecosystem response; 4) Determining the capacity of important species to acclimate or adapt to changing ocean conditions; 5) Considering multi-disciplinary, ecosystem-level research that examines acidification impacts on biodiversity and biotic interactions; and 6) Connecting potential acidification-induced ecological impacts to ecosystem services and the economy. These recommendations, while developed for the Mid-Atlantic, can be applicable to other regions will help align research towards knowledge of potential larger-scale ecological and economic impacts
The ethics of uncertainty for data subjects
Modern health data practices come with many practical uncertainties. In this paper, I argue that data subjects’ trust in the institutions and organizations that control their data, and their ability to know their own moral obligations in relation to their data, are undermined by significant uncertainties regarding the what, how, and who of mass data collection and analysis. I conclude by considering how proposals for managing situations of high uncertainty might be applied to this problem. These emphasize increasing organizational flexibility, knowledge, and capacity, and reducing hazard
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