Crumbling under Pressure

In order for an organism to maintain its form, it must be able to withstand physical perturbation, including the pull of gravity. A recent study in Nature from Porazinski and colleagues (2015) suggests that mechanisms promoting tissue tension are critical to resist the Earth’s downward pull

Examining Virtual Learning Acceptance Among Higher Learning Institutions' Lecturers: A UTAUT Theory Approach

This study examined virtual learning acceptance among Higher Learning Institutions' lecturers using the UTAUT theory approach, notably the Institute of Accountancy Arusha and the Institute of Finance Management. A descriptive research design was used in this study, and a convenient sampling technique was employed. Both primary and secondary data were used in the data collection exercise. The data collected was processed and analysed using the Statistical Package for Social Sciences. Findings revealed that performance expectancy, effort expectancy, and social influence positively affect behavioural intention. HLI's lecturers accept virtual learning. The results revealed that facilitating conditions positively affect user behaviour to accept virtual learning. The findings of this study showed that behavioural intention positively affects user behaviour when taking virtual learning. This study recommends that future studies be designed to compare and contrast the predictive power of the different competing theories, such as the theory of planned behaviour, the technology acceptance model, the theory of reasoned action, and the diffusion of innovation theory

Insights, Pearls, and Guidance on Successfully Producing and Publishing Educational Research

It is the collaborative responsibility of authors, reviewers, and editors to produce high-quality manuscripts that advance knowledge and educational practice. Experience with manuscript submissions to the American Journal of Pharmaceutical Education reveal several areas for improvement that authors can make to increase their submission success rate during the review process. These improvements include research question justification, improved clarity and details regarding methodology, concise data and results, and a discussion that frames research findings in the context of what is already known. This paper summarizes common flaws we see in submitted manuscripts and makes suggestions on how to address these areas and improve publication success

Densest local packing diversity. II. Application to three dimensions

The densest local packings of N three-dimensional identical nonoverlapping spheres within a radius Rmin(N) of a fixed central sphere of the same size are obtained for selected values of N up to N = 1054. In the predecessor to this paper [A.B. Hopkins, F.H. Stillinger and S. Torquato, Phys. Rev. E 81 041305 (2010)], we described our method for finding the putative densest packings of N spheres in d-dimensional Euclidean space Rd and presented those packings in R2 for values of N up to N = 348. We analyze the properties and characteristics of the densest local packings in R3 and employ knowledge of the Rmin(N), using methods applicable in any d, to construct both a realizability condition for pair correlation functions of sphere packings and an upper bound on the maximal density of infinite sphere packings. In R3, we find wide variability in the densest local packings, including a multitude of packing symmetries such as perfect tetrahedral and imperfect icosahedral symmetry. We compare the densest local packings of N spheres near a central sphere to minimal-energy configurations of N+1 points interacting with short-range repulsive and long-range attractive pair potentials, e.g., 12-6 Lennard-Jones, and find that they are in general completely different, a result that has possible implications for nucleation theory. We also compare the densest local packings to finite subsets of stacking variants of the densest infinite packings in R3 (the Barlow packings) and find that the densest local packings are almost always most similar, as measured by a similarity metric, to the subsets of Barlow packings with the smallest number of coordination shells measured about a single central sphere, e.g., a subset of the FCC Barlow packing. We additionally observe that the densest local packings are dominated by the spheres arranged with centers at precisely distance Rmin(N) from the fixed sphere's center.Comment: 45 pages, 18 figures, 2 table

Outflows From Evolved Stars: The Rapidly Changing Fingers Of CRL 618

Our ultimate goal is to probe the nature of the collimator of the outflows in the pre-planetary nebula CRL 618. CRL 618 is uniquely suited for this purpose owing to its multiple, bright, and carefully studied finger-shaped outflows east and west of its nucleus. We compare new Hubble Space Telescope images to images in the same filters observed as much as 11 yr ago to uncover large proper motions and surface brightness changes in its multiple finger-shaped outflows. The expansion age of the ensemble of fingers is close to 100 yr. We find strong brightness variations at the fingertips during the past decade. Deep IR images reveal a multiple ring-like structure of the surrounding medium into which the outflows propagate and interact. Tightly constrained three-dimensional hydrodynamic models link the properties of the fingers to their possible formation histories. We incorporate previously published complementary information to discern whether each of the fingers of CRL 618 are the results of steady, collimated outflows or a brief ejection event that launched a set of bullets about a century ago. Finally, we argue on various physical grounds that fingers of CRL 618 are likely to be the result of a spray of clumps ejected at the nucleus of CRL 618 since any mechanism that form a sustained set of unaligned jets is unprecedented.HST GO 11580NASA through Space Telescope Science Institute GO11580NASA NAS5-26555Boeing ScholarshipOffice of Undergraduate Academic Affairs at the University of WashingtonSpanish MICINN CSD2009-00038NASA Office of Space Science NAG5-7584Astronom

Actomyosin Pulsing in Tissue Integrity Maintenance during Morphogenesis

The actomyosin cytoskeleton is responsible for many changes in cell and tissue shape. For a long time, the actomyosin cytoskeleton has been known to exhibit dynamic contractile behavior. Recently, discrete actomyosin assembly/disassembly cycles have also been observed in cells. These so-called actomyosin pulses have been observed in a variety of contexts, including cell polarization and division, and in epithelia, where they occur during tissue contraction, folding, and extension. In epithelia, evidence suggests that actomyosin pulsing, and more generally, actomyosin turnover, is required to maintain tissue integrity during contractile processes. This review explores possible functions for pulsing in the many instances during which pulsing has been observed, and also highlights proposed molecular mechanisms that drive pulsing

Fuel-Supply-Limited Stellar Relaxation Oscillations: Application to Multiple Rings around AGB Stars and Planetary Nebulae

We describe a new mechanism for pulsations in evolved stars: relaxation oscillations driven by a coupling between the luminosity-dependent mass-loss rate and the H fuel abundance in a nuclear-burning shell. When mass loss is included, the outward flow of matter can modulate the flow of fuel into the shell when the stellar luminosity is close to the Eddington luminosity $L_{\rm Edd}$. When the luminosity drops below $L_{\rm Edd}$, the mass outflow declines and the shell is re-supplied with fuel. This process can be repetitive. We demonstrate the existence of such oscillations and discuss the dependence of the results on the stellar parameters. In particular, we show that the oscillation period scales specifically with the mass of the H-burning relaxation shell (HBRS), defined as the part of the H-burning shell above the minimum radius at which the luminosity from below first exceeds the Eddington threshold at the onset of the mass loss phase. For a stellar mass M_*\sim 0.7\Msun, luminosity L_*\sim 10^4\Lsun, and mass loss rate |\dot M|\sim 10^{-5}\Msun yr$^{-1}$, the oscillations have a recurrence time $\sim 1400$ years $\sim 57\tau_{\rm fsm}$, where $\tau_{\rm fsm}$ is the timescale for modulation of the fuel supply in the HBRS by the varying mass-loss rate. This period agrees with the $\sim$ 1400-year period inferred for the spacings between the shells surrounding some planetary nebulae, and the the predictied shell thickness, of order 0.4 times the spacing, also agrees reasonably well.Comment: 15 pages TeX, 1 ps figure submitted to Ap

Refactoring for parameterizing Java classes

Type safety and expressiveness of many existing Java libraries and theirclient applications would improve, if the libraries were upgraded to definegeneric classes. Efficient and accurate tools exist to assist clientapplications to use generics libraries, but so far the libraries themselvesmust be parameterized manually, which is a tedious, time-consuming, anderror-prone task. We present a type-constraint-based algorithm forconverting non-generic libraries to add type parameters. The algorithmhandles the full Java language and preserves backward compatibility, thusmaking it safe for existing clients. Among other features, it is capableof inferring wildcard types and introducing type parameters formutually-dependent classes. We have implemented the algorithm as a fullyautomatic refactoring in Eclipse.We evaluated our work in two ways. First, our tool parameterized code thatwas lacking type parameters. We contacted the developers of several ofthese applications, and in all cases where we received a response, theyconfirmed that the resulting parameterizations were correct and useful.Second, to better quantify its effectiveness, our tool parameterizedclasses from already-generic libraries, and we compared the results tothose that were created by the libraries' authors. Our tool performed therefactoring accurately -- in 87% of cases the results were as good as thosecreated manually by a human expert, in 9% of cases the tool results werebetter, and in 4% of cases the tool results were worse

The role of data reuse in the apprenticeship process

The availability of research data through digital repositories has made data reuse a possibility in a growing number of fields. This paper reports on the results of interviews with 27 zoologists, 43 quantitative social scientists and 22 archaeologists. It examines how data reuse contributes to the apprenticeship process and aids students in becoming full members of scholarly disciplines. Specifically, it investigates how data reuse contributes to the processes by which novice researchers join academic communities of practice. We demonstrate how projects involving data reuse provide a unique opportunity for advisors to mentor novices through the process of creating knowledge. In these situations, senior researchers model general reuse practices and impart skills for their students to use in the future when selecting, evaluating, and analyzing data they did not collect. For novices, data reuse constitutes a form of legitimate peripheral participation, a way for them to enter the community of practice by analyzing data that has been previously collected and reflecting on others' methodologies. Our study findings indicate that reuse occurs across each target community studied. They also suggest how repositories can help foster a reuse culture by providing access to data and building trust in research communities.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106839/1/14505001051_ftp.pd

Looting Hoards of Gold and Poaching Spotted Owls: Data Confidentiality Among Archaeologists & Zoologists

Researchers in the social and health sciences are used to dealing with confidential data, and repositories in these areas have developed mechanisms to prevent unethical or illegal disclosure of this data. However, other scientific communities also collect data whose disclosure may cause harm to communities, cultures, or the environment. This paper presents results from 62 interviews and observations with archaeologists and zoologists. It focuses on how researchers’ perceptions of potential harm influence attitudes about data confidentiality, and how these, in turn, influence opinions about who should be responsible for managing access to data. This is particularly problematic in archaeology when harm is not to a living individual but is targeted at a community or culture that may or may not have living representatives, and in zoology when an environment or a species may be at risk. We find that while both archaeologists and zoologists view location information as highly important and valuable in facilitating use and reuse of data, they also acknowledge that location should at times be considered confidential information since it can be used to facilitate the destruction of cultural property through looting or decimation of endangered species through poaching. While researchers in both disciplines understand the potential dangers of allowing disclosure of this information, they disagree about who should take responsibility for access decisions and conditions.The DIPIR Project was made possible by a National Leadership Grant from the Institute for Museum and Library Services, LG-06-10-0140-10, “Dissemination Information Packages for Information Reuse.”Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/115883/1/Frank_etal_ASIST2015_Looting_Hoards_of_Gold_postprint.pdfDescription of Frank_etal_ASIST2015_Looting_Hoards_of_Gold_postprint.pdf : Conference pape