2,526 research outputs found
Controlled surface initiated polymerization of N-isopropylacrylamide from polycaprolactone substrates for regulating cell attachment and detachment
Poly(ε-caprolactone) (PCL) substrates were modified with thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) brushes to direct and control cellular attachment and detachment. Prior to brush growth, the surface of PCL was activated by a diamine to allow for initiator coupling. Infrared spectra taken before and after cell culturing demonstrated the covalently attached nature of the PNIPAM brushes. PCL is a biocompatible polymer and to prove that the modifications described above did not change this characteristic property, a cell attachment/detachment study was carried out. The modified substrates showed a lower cell attachment when compared to PCL alone and to PCL films modified with the initiator. The possibility to detach the cells in the form of a sheet was proved using PNIPAM-modified PCL films by lowering the temperature to 25 °C. No relevant detachment was shown by the unmodified or by the initiator modified surfaces. This confirmed that the detachment was temperature dependent and not connected to other factors such as polymer swelling. These functionalized polymeric films can find applications as smart cell culture systems in regenerative medicine applications
A neural analogue of the worst performance rule: Insights from single-trial event-related potentials
Pair production with electron capture in peripheral collisions of relativistic heavy ions
The production of electron-positron pairs with the capture of the electron in
an atomic orbital is investigated for the conditions of the Relativistic Heavy
Ion Collider (RHIC) and the Large Hadron Collider LHC). Dirac wave functions
for the leptons are used, taking corrections to orders of Z.alpha into account.
The dependence on the transverse momentum transfer is studied and the accuracy
of the equivalent photon approximation is discussed as a function of the
nuclear charge.Comment: 4 postscript figure
Deuteron Photodissociation in Ultraperipheral Relativistic Heavy-Ion on Deuteron Collisions
In ultraperipheral relativistic deuteron on heavy-ion collisions, a photon
emitted from the heavy nucleus may dissociate the deuterium ion. We find
deuterium breakup cross sections of 1.38 barns for deuterium-gold collisions at
a center of mass energy of 200 GeV per nucleon, as studied at the Relativistic
Heavy Ion Collider, and 2.49 barns for deuterium-lead collisions at a center of
mass energy of 6.2 TeV, as proposed for the Large Hadron Collider. This cross
section includes an energy-independent 140 mb contribution from hadronic
diffractive dissociation. At the LHC, the cross section is as large as that of
hadronic interactions. The estimated error is 5%. Deuteron dissociation could
be used as a luminosity monitor and a `tag' for moderate impact parameter
collisions.Comment: Final version, to appear in Phys. Rev. C. Diffractive dissociation
included 10 pages with 3 figure
From Predicting Solar Activity to Forecasting Space Weather: Practical Examples of Research-to-Operations and Operations-to-Research
The successful transition of research to operations (R2O) and operations to
research (O2R) requires, above all, interaction between the two communities. We
explore the role that close interaction and ongoing communication played in the
successful fielding of three separate developments: an observation platform, a
numerical model, and a visualization and specification tool. Additionally, we
will examine how these three pieces came together to revolutionize
interplanetary coronal mass ejection (ICME) arrival forecasts. A discussion of
the importance of education and training in ensuring a positive outcome from
R2O activity follows. We describe efforts by the meteorological community to
make research results more accessible to forecasters and the applicability of
these efforts to the transfer of space-weather research.We end with a
forecaster "wish list" for R2O transitions. Ongoing, two-way communication
between the research and operations communities is the thread connecting it
all.Comment: 18 pages, 3 figures, Solar Physics in pres
Potential energy landscape-based extended van der Waals equation
The inherent structures ({\it IS}) are the local minima of the potential
energy surface or landscape, , of an {\it N} atom system.
Stillinger has given an exact {\it IS} formulation of thermodynamics. Here the
implications for the equation of state are investigated. It is shown that the
van der Waals ({\it vdW}) equation, with density-dependent and
coefficients, holds on the high-temperature plateau of the averaged {\it IS}
energy. However, an additional ``landscape'' contribution to the pressure is
found at lower . The resulting extended {\it vdW} equation, unlike the
original, is capable of yielding a water-like density anomaly, flat isotherms
in the coexistence region {\it vs} {\it vdW} loops, and several other desirable
features. The plateau energy, the width of the distribution of {\it IS}, and
the ``top of the landscape'' temperature are simulated over a broad reduced
density range, , in the Lennard-Jones fluid. Fits to the
data yield an explicit equation of state, which is argued to be useful at high
density; it nevertheless reproduces the known values of and at the
critical point
The flood, the channels, and the dykes : managing legal information a globalized and digital world
Information search and retrieval are part of daily routines of the legal profession. Lawyers, judges, prosecutors, and legal clerks usually access a number of electronic resources to browse, search, select, or update legal contents. Legal databases have currently become large digital libraries where the tasks related to information-seeking may sometimes be cumbersome. Adding semantics to support information search may provide significant results in terms of efficiency, efficacy, and user satisfaction. Semantic technologies may be able to improve legal information search in the judicial and lawyers' domains. However, legal professionals sometimes prefer following routines than changing their information search behavior. New trends in legal ontologies and Semantic Web technologies may help to improve both professional and laymen's skills
An experimental measurement of corona discharge using laser Dopplervelocimetry
A point to plane testing discharge system was constructed allowing the flow of air to pass, circulate and return to its initial status, when corona is initiated by the alternating applied voltage on the stressed electrode. The corona wind velocity was measured by means of a laser Doppler velocimetry system implemented and calibrated in the laboratory. The velocity measurement was carried out without disturbing the field configuration intensity or the wind flow. The direction and pattern of the corona electric wind was visualized and observed through a laser curtain; this was achieved by guiding smoke to the discharge medium near the stressed electrode. Velocity measurements were obtained for various radial distances r, taken on the central discharge axis for several inter-electrode distances b. The direct observation of the obtained data shows an increase of the corona wind velocity with the applied voltage and the corona discharge current and substantial decrease as the radial distance is enlarged. An experimental investigation was conducted in the research laboratory to use electric wind corona discharge and enhance the available information supporting the corona discharge and applied voltage relationship along with the geometrical system parameter
Heterotic SO(32) model building in four dimensions
Four dimensional heterotic SO(32) orbifold models are classified
systematically with model building applications in mind. We obtain all Z3, Z7
and Z2N models based on vectorial gauge shifts. The resulting gauge groups are
reminiscent of those of type-I model building, as they always take the form
SO(2n_0)xU(n_1)x...xU(n_{N-1})xSO(2n_N). The complete twisted spectrum is
determined simultaneously for all orbifold models in a parametric way depending
on n_0,...,n_N, rather than on a model by model basis. This reveals interesting
patterns in the twisted states: They are always built out of vectors and
anti--symmetric tensors of the U(n) groups, and either vectors or spinors of
the SO(2n) groups. Our results may shed additional light on the S-duality
between heterotic and type-I strings in four dimensions. As a spin-off we
obtain an SO(10) GUT model with four generations from the Z4 orbifold.Comment: 1+37 pages LaTeX, some typos in table 4 corrected, and we have
included some discussion on exceptional shift vectors which ignored in the
previous version
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