1,040 research outputs found
Nano-chip for cancer diagnostics
Exosomes are vesicles with a size range of 30 to 50nm, which are secreted by a cell into its surroundings..
Medical applications based on nanotechnology
Poly-lactic-co-glycolic acid can form nanoparticles which can be applied in nanomedicine as delivery vehicle for therapeutic agents. Here the aim is to reduce negative side-effects and to obtain higher local concentrations at the site of action. This work is about determining the binding-capacity of PLGA nanoparticles to several substances, applying a small set of model proteins. Our aim was to find out, whether PLGA nanoparticles can transport drugs in order to make drug targeting in medicine easier. This would show us a new section of medicine with new ways of therapy methods
General Relativistic Electromagnetic Fields of a Slowly Rotating Magnetized Neutron Star. I. Formulation of the equations
We present analytic solutions of Maxwell equations in the internal and
external background spacetime of a slowly rotating magnetized neutron star. The
star is considered isolated and in vacuum, with a dipolar magnetic field not
aligned with the axis of rotation. With respect to a flat spacetime solution,
general relativity introduces corrections related both to the monopolar and the
dipolar parts of the gravitational field. In particular, we show that in the
case of infinite electrical conductivity general relativistic corrections due
to the dragging of reference frames are present, but only in the expression for
the electric field. In the case of finite electrical conductivity, however,
corrections due both to the spacetime curvature and to the dragging of
reference frames are shown to be present in the induction equation. These
corrections could be relevant for the evolution of the magnetic fields of
pulsars and magnetars. The solutions found, while obtained through some
simplifying assumption, reflect a rather general physical configuration and
could therefore be used in a variety of astrophysical situations.Comment: A few typos corrected; matches the versions in MNRA
Active drug targeting
Over 100 years ago, Paul Ehrlich first proposed the side-chain theory to explain how living cells mount an immune response in reaction to an infection. His theory stated that upon the encounter of a threat, cells express side-chains to bind dangerous toxins. These side-chains, which he later named receptors, can break off the cell and circulate throughout the body (i.e. antibodies). Specific antibodies link to particular antigens in the same way that Emil Fischer proposed enzymes bind to their receptors, “as lock and key”. Ehrlich described these so-called “keys” or antibodies as “magic bullets”, which target toxins without harming the body. In recent years, research has focused on using antibodies not only for detection of infection, but also as aids for drug targeting. Thereby, antibodies are bound to the surface of carriers (e.g. nanoparticles) and facilitate a directed transport to a specific organ or site in the body. Aptamer- peptide- or folic acid-doped carriers furthermore have been shown to specifically target cancer cells. By using hydrophilic structures as carriers (e.g. polyethylene glycol), negative side effects resulting from the accumulation of innate proteins can be prevented. Currently, there are drug carriers in the pre-clinical development phase for the treatment of bowel cancer. Thereby, nano polymer capsules coated with a specific antibody are used to target a glycoprotein expressed on bowel cancer cells. The polymers have a size of approximately 500 nm and are produced with a so-called “layer-by-layer” procedure. Once the carrier has reached its target site, the drug needs to be released in a controlled manner. This can be facilitated, for example, by applying a magnetic field in the case of iron oxide particles. Once these particles are taken up by the cells, magnetic radiation can be used to excite the particles, resulting in the rupture of the cell and subsequent cell death
Turning Points in the Evolution of Isolated Neutron Stars' Magnetic Fields
During the life of isolated neutron stars (NSs) their magnetic field passes
through a variety of evolutionary phases. Depending on its strength and
structure and on the physical state of the NS (e.g. cooling, rotation), the
field looks qualitatively and quantitatively different after each of these
phases. Three of them, the phase of MHD instabilities immediately after NS's
birth, the phase of fallback which may take place hours to months after NS's
birth, and the phase when strong temperature gradients may drive thermoelectric
instabilities, are concentrated in a period lasting from the end of the
proto--NS phase until 100, perhaps 1000 years, when the NS has become almost
isothermal. The further evolution of the magnetic field proceeds in general
inconspicuous since the star is in isolation. However, as soon as the product
of Larmor frequency and electron relaxation time, the so-called magnetization
parameter, locally and/or temporally considerably exceeds unity, phases, also
unstable ones, of dramatic changes of the field structure and magnitude can
appear. An overview is given about that field evolution phases, the outcome of
which makes a qualitative decision regarding the further evolution of the
magnetic field and its host NS.Comment: References updated, typos correcte
Effects of temperature and plant diversity on orthopterans and leafhoppers in calcareous dry grasslands
Abstract: In mountains, current land-use changes are altering plant communities of semi-natural grasslands with potential cascading effects on associated herbivores. Besides vegetation changes, temperature is also a key driver of insect diversity, and in the European Alps is predicted to increase by 0.25\ua0\ub0C per decade. Understanding herbivore responses to temperature and plant composition changes in mountain environments is of increasing importance. Our study aims at investigating the response to temperature and plant diversity and composition of two key herbivore groups (orthopterans and leafhoppers) belonging to contrasting feeding guilds (chewers vs. sap-feeders). We hypothesized that orthopteran diversity would be driven by temperature while leafhoppers by plant community composition. We selected 15 dry calcareous grasslands ranging from 100 to 1330\ua0m a.s.l. along two independent gradients of plant diversity and temperature. We sampled orthopteran and leafhopper species richness and abundance by sweep-netting. Consistent with their low feeding specialisation, orthopteran species richness and community composition were only driven by temperature. By contrast, leafhopper species richness was not affected by temperature nor by plant diversity but leafhopper community composition was strongly influenced by plant species composition. This response can be explained by the higher host feeding specialisation of many leafhopper species. Species rarity and mobility did not change the response of the diversity of both groups, but orthopteran abundance increased with temperature only for highly mobile species. Altogether, our results suggest that future responses of grassland herbivores to vegetation changes and temperature warming are highly variable and depend on the feeding strategy and specialisation of the focal herbivore group. Implications for insect conservation: Leafhoppers emerged to be particularly sensitive to potential management or climate-induced change in vegetation composition, while orthopterans are expected to respond directly to temperature warming due to their relaxed association with plant community diversity and composition
A hierarchical model for aging
We present a one dimensional model for diffusion on a hierarchical tree
structure. It is shown that this model exhibits aging phenomena although no
disorder is present. The origin of aging in this model is therefore the
hierarchical structure of phase space.Comment: 10 pages LaTeX, 4 postscript-figures include
Nuclear Charge Radius of Be
The nuclear charge radius of Be was precisely determined using the
technique of collinear laser spectroscopy on the transition in the Be ion. The mean square charge radius increases
from Be to Be by \delta ^{10,12} = 0.69(5) \fm^{2}
compared to \delta ^{10,11} = 0.49(5) \fm^{2} for the
one-neutron halo isotope Be. Calculations in the fermionic molecular
dynamics approach show a strong sensitivity of the charge radius to the
structure of Be. The experimental charge radius is consistent with a
breakdown of the N=8 shell closure.Comment: 5 pages, 3 figure
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