The relationship between the transverse and longitudinal nuclear magnetic resonance relaxation rates of muscle water

Whole frog sartorius and gastrocnemius muscles were incubated in Ringer's solutions, either unenriched or enriched with H2 17Oor 2D2O. Subsequently, the rates of transverse (1/T2) and of longitudinal (1/T1) nuclear magnetic relaxation were measured for 17O, 2D, and 1H at room temperature and at 8.1 MHz. The ratio (T1/T2) for 17O was measured to be approximately 1.5–2.0, close to the value roughly estimated from the Larmor frequency dependence of 1/T1 alone over the range 4.3–8.1 MHz. On the other hand (T1/T2) for 2D and 1H were both measured to lie in the range 9–11. Insofar as the entire 17O signal was detected, the data indicate the presence of an exchange mechanism between the major fraction of intracellular water and a minor fraction characterized by enhanced rates of relaxation. Possible molecular mechanisms are presented

Product structures for Legendrian contact homology

Legendrian contact homology (LCH) is a powerful non-classical invariant of Legendrian knots. Linearization makes the LCH computationally tractable at the expense of discarding nonlinear (and non-commutative) information. To recover some of the nonlinear information while preserving computability, we introduce invariant cup and Massey products – and, more generally, an A∞ structure – on the linearized LCH. We apply the products and A∞ structure in three ways: to find infinite families of Legendrian knots that are not isotopic to their Legendrian mirrors, to reinterpret the duality theorem of the fourth author in terms of the cup product, and to recover higher-order linearizations of the LCH

Effectiveness of 2-D Views for 6-D Robotics Simulation Maneuvers

This study examined operator performance on 6-D robotics simulation maneuvers using a single 2-D view of the robot arm. The BORIS simulator, developed by NASA to support Generic Robotics Training, was used to present four “fly-to” tasks with views representing combinations of good and poor control-display movement compatibility and perceptual quality. Translational (x, y, z) and rotational (pitch, yaw, roll) accuracies were used to assess performance. A significant interaction between movement compatibility and perceptual quality was found for both the overall translational and y accuracy measures (p = 0.0289 and p = 0.0155, respectively). This interaction appeared to indicate that performance was hindered only if both factors were poor. Perceptual quality significantly affected the z accuracy and pitch accuracy measures (p = 0.0461 and p = 0.0429, respectively) with the views identified as poor perceptual quality actually yielding better performance. These results suggest that performance on a 6-D robotics maneuver is not necessarily hindered by using only a 2-D view. If a single view cannot simultaneously provide both good movement compatibility and good perceptual quality, the results suggest that either one is sufficient with respect to overall translational accuracy.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline

The Minimal Length of a Lagrangian Cobordism between Legendrians

To investigate the rigidity and flexibility of Lagrangian cobordisms between Legendrian submanifolds, we investigate the minimal length of such a cobordism, which is a $1$-dimensional measurement of the non-cylindrical portion of the cobordism. Our primary tool is a set of real-valued capacities for a Legendrian submanifold, which are derived from a filtered version of Legendrian Contact Homology. Relationships between capacities of Legendrians at the ends of a Lagrangian cobordism yield lower bounds on the length of the cobordism. We apply the capacities to Lagrangian cobordisms realizing vertical dilations (which may be arbitrarily short) and contractions (whose lengths are bounded below). We also study the interaction between length and the linking of multiple cobordisms as well as the lengths of cobordisms derived from non-trivial loops of Legendrian isotopies.Comment: 33 pages, 9 figures. v2: Minor corrections in response to referee comments. More general statement in Proposition 3.3 and some reorganization at the end of Section

Analysis of College Students’ Personal Health Information Activities: Online Survey

Background: With abundant personal health information at hand, individuals are faced with a critical challenge in evaluating the informational value of health care records to keep useful information and discard that which is determined useless. Young, healthy college students who were previously dependents of adult parents or caregivers are less likely to be concerned with disease management. Personal health information management (PHIM) is a special case of personal information management (PIM) that is associated with multiple interactions among varying stakeholders and systems. However, there has been limited evidence to understand informational or behavioral underpinning of the college students’ PHIM activities, which can influence their health in general throughout their lifetime. Objective: This study aimed to investigate demographic and academic profiles of college students with relevance to PHIM activities. Next, we sought to construct major PHIM-related activity components and perceptions among college students. Finally, we sought to discover major factors predicting core PHIM activities among college students we sampled. Methods: A Web survey was administered to collect responses about PHIM behaviors and perceptions among college students from the University of Kentucky from January through March 2017. A total of 1408 college students were included in the analysis. PHIM perceptions, demographics, and academic variations were used as independent variables to predict diverse PHIM activities using a principal component analysis (PCA) and hierarchical regression analyses (SPSS v.24, IBM Corp, Armonk, NY, USA). Results: Majority of the participants were female (956/1408, 67.90%), and the age distribution of this population included an adequate representation of college students of all ages. The most preferred health information resources were family (612/1408, 43.47%), health care professionals (366/1408, 26.00%), friends (27/1408, 1.91%), and the internet (157/1408, 11.15%). Organizational or curatorial activities such as Arranging, Labeling, Categorizing, and Discarding were rated low (average=3.21, average=3.02, average=2.52, and average=2.42, respectively). The PCA results suggested 3 components from perception factors labeled as follows: Assistance (alpha=.85), Awareness (alpha=.716), and Difficulty (alpha=.558). Overall, the Demographics and Academics variables were not significant in predicting dependent variables such as Labeling, Categorizing, Health Education Materials, and Discarding, whereas they were significant for other outcome variables such as Sharing, Collecting, Knowing, Insurance Information, Using, and Owning. Conclusions: College years are a significant time for students to learn decision-making skills for maintaining information, a key aspect of health records, as well as for educators to provide appropriate educational and decision aids in the environment of learning as independent adults. Our study will contribute to better understand knowledge about specific skills and perceptions for college students’ practice of effective PHIM throughout their lives

Permeability evolution in sandstone due to injection of CO2-saturated brine or supercritical CO2 at reservoir conditions

We measured the change in permeability of two selected sandstones (Berea, Fonteinebleau) due to injection of CO2-saturated (“live”) brine, unsaturated (“dead”) brine or supercritical (sc) CO2 at reservoir conditions. We found that the permeability did not significantly change in a clean sandstone consisting of pure quartz (Fonteinemebleau) due to live or dead brine injection, although permeability changed due to scCO2 injection by ~23%. The permeability in the Berea sandstone, however, changed due to live or dead brine injection, by up to 35%; this permeability reduction in Berea sandstone was likely caused by fines release and subsequent pore throat plugging as the damage was more significant at higher injection rates. We expect that this phenomenon – i.e. rock permeability reduction due to CO2 injection into the formation – can have a significant and detrimental influence on CO2 injectivity, which would be reduced accordingly