966 research outputs found
Electrostatics of ions inside the nanopores and trans-membrane channels
A model of a finite cylindrical ion channel through a phospholipid membrane
of width separating two electrolyte reservoirs is studied. Analytical
solution of the Poisson equation is obtained for an arbitrary distribution of
ions inside the trans-membrane pore. The solution is asymptotically exact in
the limit of large ionic strength of electrolyte on the two sides of membrane.
However, even for physiological concentrations of electrolyte, the
electrostatic barrier sizes found using the theory are in excellent agreement
with the numerical solution of the Poisson equation. The analytical solution is
used to calculate the electrostatic potential energy profiles for pores
containing charged protein residues. Availability of a semi-exact interionic
potential should greatly facilitate the study of ionic transport through
nanopores and ion channels
Using a Computer Module to Teach Use of the EpiPen®
Background: The medical literature suggests that patients and physicians are deficient in their ability to use a self-injectable epinephrine device (EpiPen®) for management of anaphylaxis. This study aims to determine whether a computer module is an effective tool for the instruction of a technical skill to medical trainees.Methods: We conducted a two group comparison study of 35 Post-Graduate Year 1 and 2 Family Medicine residents. Participants were instructed on use of the EpiPen® using either a written module or a computer module. Participants were evaluated on use of the EpiPen® using standardized objective outcome measures by a blinded assessor. Assessments took place prior to and following instruction, using the assigned learning modality.Results: There were 34 participants who completed the study. Both groups demonstrated significant improvement in demonstrating use of the EpiPen® following training (p <0.001 for both). A significant post-training difference favouring the computer module learners over the written module learners was observed (p = 0.035). However, only 53% and 18% of candidates (computer module and written module, respectively) were able to correctly perform all of the checklist steps.Conclusion: While our findings suggest computer modules represent an effective modality for teaching use of the EpiPen® to medical trainees, the low number of candidates who were able to perform all the checklist items regardless of modality needs to be addressed
EXAMINING THE INTRA- AND INTER-DAY RELIABILITY OF THE VALD HUMANTRAK FOR RANGE OF MOTION OF THE SHOULDER IN FIXED- AND FREE-RANGE CONDITIONS
The purpose of this study was to assess the reliability of the VALD HumanTrak system for estimating shoulder range of motion in the sagittal and frontal planes. Intra- and inter-day reliability was assessed during fixed- and free-range shoulder movements. ICC ranged from good to excellent for abduction (0.753 - 0.959) and flexion (0.868 - 0.975) and poor to good for adduction (0.417 - 0.893) and extension (0.443 - 0.757). The VALD HumanTrak can be a reliable tool to estimate shoulder range of motion within the same day and across multiple days
Far-UV Emissions of the Sun in Time: Probing Solar Magnetic Activity and Effects on Evolution of Paleo-Planetary Atmospheres
We present and analyze FUSE observations of six solar analogs. These are
single, main-sequence G0-5 strs selected as proxies for the Sun at several
stages of its main-sequence lifetime. The emission features in the FUSE
920-1180 A wavelength range allow for a critical probe of the hot plasma over
three decades in temperature. Using the flux ratio CIII 1176/977 as
diagnostics, we investigate the dependence of the electron pressure of the
transition region as a function of the rotation period, age and magnetic
activity. The results from these solar proxies indicate that the electron
pressure of the stellar ~10^5-K plasma decreases by a factor of about 70
between the young, fast-rotating magnetically active star and the old,
slow-rotating inactive star. Also, the observations indicate that the average
surface fluxes of emission features strongly decrease with increasing stellar
age and longer rotation period. The emission flux evolution with age or
rotation period is well fitted by power laws, which become steeper from cooler
chromospheric (10^4 K) to hotter coronal (10^7 K) plasma. The relationship for
the integrated (920-1180 A) FUSE flux indicates that the solar far-ultraviolet
emissions were about twice the present value 2.5 Gyr ago and about 4 times the
present value 3.5 Gyr ago. Note also that the FUSE/FUV flux of the Zero-Age
Main Sequence Sun could have been higher by as much as 50 times. Our analysis
suggests that the strong FUV emissions of the young Sun may have played a
crucial role in the developing planetary system, in particular through the
photoionization, photochemical evolution and possible erosion of the planetary
atmospheres. (abridged)Comment: 15 pages, 8 figures, accepted for publication in Ap
TRANSFERABILITY OF A PREVIOUSLY VALIDATED IMU SYSTEM FOR LOWER EXTREMITY KINEMATICS
This study tested transferability and validity of an Inertial Measurement Unit (IMU) system for estimation of lower limb kinematics. Peak hip, knee, and plantarflexion angles and sagittal plane range of motion (ROM) were compared during body weight squats (BWSQ) and countermovement jumps (CMJ) in 16 participants using root mean square error (RMSE) and intraclass correlation coefficients (ICC). RMSE wa
Improving mobile user interface testing with model driven monkey search
Testing mobile applications often relies on tools, such
as Exerciser Monkey for Android systems, that simulate user
input. Exerciser Monkey, for example, generates random events
(e.g., touches, gestures, navigational keys) that give developers a
sense of what their application will do when deployed on real
mobile phones with real users interacting with it. These tools,
however, have no knowledge of the underlying applications’ structures and only interact with them randomly or in a predefined
manner (e.g., if developers designed scenarios, a labour-intensive
task) – making them slow and poor at finding bugs.
In this paper, we propose a novel control flow structure able
to represent the code of Android applications, including all the
interactive elements. We show that our structure can increase
the effectiveness (higher coverage) and efficiency (removing
duplicate/redundant tests) of the Exerciser Monkey by giving it
knowledge of the test environment. We compare the interface
coverage achieved by the Exerciser Monkey with our new
Monkey++ using a depth first search of our control flow structure
and show that while the random nature of Exerciser Monkey
creates slow test suites of poor coverage, the test suite created
by a depth first search is one order of magnitude faster and
achieves full coverage of the user interaction elements. We believe
this research will lead to a more effective and efficient Exerciser
Monkey, as well as better targeted search based techniques for
automated Android testing
PDBTM: Protein Data Bank of transmembrane proteins after 8 years
The PDBTM database (available at http://pdbtm
.enzim.hu), the first comprehensive and up-to-date
transmembrane protein selection of the Protein
Data Bank, was launched in 2004. The database
was created and has been continuously updated
by the TMDET algorithm that is able to distinguish
between transmembrane and non-transmembrane
proteins using their 3D atomic coordinates only.
The TMDET algorithm can locate the spatial positions
of transmembrane proteins in lipid bilayer as
well. During the last 8 years not only the size of the
PDBTM database has been steadily growing from
~400 to 1700 entries but also new structural
elements have been identified, in addition to the
well-known a-helical bundle and b-barrel structures.
Numerous ‘exotic’ transmembrane protein structures
have been solved since the first release,
which has made it necessary to define these new
structural elements, such as membrane loops or
interfacial helices in the database. This article
reports the new features of the PDBTM database
that have been added since its first release, and
our current efforts to keep the database
up-to-date and easy to use so that it may continue
to serve as a fundamental resource for the scientific
community
A study of velocity fields in the transition region of Epsilon Eri (K2 V)
Analyses of the widths and shifts of optically thin emission lines in the
ultraviolet spectrum of the active dwarf Epsilon Eri (K2 V) are presented. The
spectra were obtained using the Space Telescope Imaging Spectrograph on the
Hubble Space Telescope and the Far Ultraviolet Spectroscopic Explorer. The line
widths are used to find the non-thermal energy density and its variation with
temperature from the chromosphere to the upper transition region. The energy
fluxes that could be carried by Alfven and acoustic waves are investigated, to
test their possible roles in coronal heating. Acoustic waves do not appear to
be a viable means of coronal heating. There is, in principle, ample flux in
Alfven waves, but detailed calculations of wave propagation are required before
definite conclusions can be drawn about their viability. The high sensitivity
and spectral resolution of the above instruments have allowed two-component
Gaussian fits to be made to the profiles of the stronger transition region
lines. The broad and narrow components which result share some similarities
with those observed in the Sun, but in Epsilon Eri the broad component is
redshifted relative to the narrow component and contributes more to the total
line flux. The possible origins of the two components and the energy fluxes
implied are discussed. On balance our results support the conclusion of Wood,
Linsky & Ayres, that the narrow component is related to Alfven waves reaching
to the corona, but the origin of the broad component is not clear.Comment: 19 pages, 16 figures. Accepted for publication by MNRA
- …