514 research outputs found
XTribe: a web-based social computation platform
In the last few years the Web has progressively acquired the status of an
infrastructure for social computation that allows researchers to coordinate the
cognitive abilities of human agents in on-line communities so to steer the
collective user activity towards predefined goals. This general trend is also
triggering the adoption of web-games as a very interesting laboratory to run
experiments in the social sciences and whenever the contribution of human
beings is crucially required for research purposes. Nowadays, while the number
of on-line users has been steadily growing, there is still a need of
systematization in the approach to the web as a laboratory. In this paper we
present Experimental Tribe (XTribe in short), a novel general purpose web-based
platform for web-gaming and social computation. Ready to use and already
operational, XTribe aims at drastically reducing the effort required to develop
and run web experiments. XTribe has been designed to speed up the
implementation of those general aspects of web experiments that are independent
of the specific experiment content. For example, XTribe takes care of user
management by handling their registration and profiles and in case of
multi-player games, it provides the necessary user grouping functionalities.
XTribe also provides communication facilities to easily achieve both
bidirectional and asynchronous communication. From a practical point of view,
researchers are left with the only task of designing and implementing the game
interface and logic of their experiment, on which they maintain full control.
Moreover, XTribe acts as a repository of different scientific experiments, thus
realizing a sort of showcase that stimulates users' curiosity, enhances their
participation, and helps researchers in recruiting volunteers.Comment: 11 pages, 2 figures, 1 table, 2013 Third International Conference on
Cloud and Green Computing (CGC), Sept. 30 2013-Oct. 2 2013, Karlsruhe,
German
Cortico-spinal modularity in the parieto-frontal system: a new perspective on action control
: Classical neurophysiology suggests that the motor cortex (MI) has a unique role in action control. In contrast, this review presents evidence for multiple parieto-frontal spinal command modules that can bypass MI. Five observations support this modular perspective: (i) the statistics of cortical connectivity demonstrate functionally-related clusters of cortical areas, defining functional modules in the premotor, cingulate, and parietal cortices; (ii) different corticospinal pathways originate from the above areas, each with a distinct range of conduction velocities; (iii) the activation time of each module varies depending on task, and different modules can be activated simultaneously; (iv) a modular architecture with direct motor output is faster and less metabolically expensive than an architecture that relies on MI, given the slow connections between MI and other cortical areas; (v) lesions of the areas composing parieto-frontal modules have different effects from lesions of MI. Here we provide examples of six cortico-spinal modules and functions they subserve: module 1) arm reaching, tool use and object construction; module 2) spatial navigation and locomotion; module 3) grasping and observation of hand and mouth actions; module 4) action initiation, motor sequences, time encoding; module 5) conditional motor association and learning, action plan switching and action inhibition; module 6) planning defensive actions. These modules can serve as a library of tools to be recombined when faced with novel tasks, and MI might serve as a recombinatory hub. In conclusion, the availability of locally-stored information and multiple outflow paths supports the physiological plausibility of the proposed modular perspective
Surface area of lipid membranes regulates the DNA-binding capacity of cationic liposomes.
We have applied electrophoresis on agarose gels to investigate the DNA-binding capacity of cationic liposomes made of cationic DC-cholesterol and neutral dioleoylphosphatidylethanolamine as a function of membrane charge density and cationic lipid/DNA charge ratio. While each cationic liposome formulation exhibits a distinctive DNA-protection ability, here we show that such a capacity is universally regulated by surface area of lipid membranes available for binding in an aspecific manner. The relevance of DNA protection for gene transfection is also discussed
Impact of sublingual immunotherapy on seasonal asthma and skin reactivity in children allergic to Parietaria pollen treated with inhaled fluticasone propionate
Immunotherapy is a recognized treatment for allergic respiratory diseases
Are PEI-coated SWCNTs conjugated with hepatitis A virus? A chemical study with SEM, Z-potential, EDXD and RT-PCR
The conjugation between nanotubes, coated with different doses of polyethylene imine (PEI)
and hepatitis A virus (HAV) was investigated by scanning electron microscopy, Z-potential,
thermogravimetric and differential thermal analysis, transmission electron microscopy, energy
dispersive x-ray diffraction (EDXD) and reverse transcript polymerase chain reaction
(RT-PCR). For the first time, to our knowledge, evidence is obtained that conjugation between
the nanotubes and the HAV occurs and that it has an (at least a partial) electrostatic character.
Since all components of the conjugated systems, nanotubes, coating material and virus are
characterized by different peak shapes in the selected q range, it was possible to infer that
conjugation occurred. RT-PCR measurements confirmed that the conjugation of the coated
nanotubes and HAV occurred and the result was stable. This opens up the prospect of probing
the coated nanotubes as intra-cellular carriers in transfection processes of the virus. Further
biological applications will concern a possible vaccine especially for non-replicative
viruses
On the correlation between phase evolution of lipoplexes/anionic lipid mixtures and DNA release
We investigated the structural evolution of three lipoplex formulations when interacting with anionic lipids by synchrotron small angle x-ray diffraction, while the extent of DNA release from lipoplexes by anionic lipids was evaluated by gel electrophoresis. Lipoplexes formed lamellar phases when mixed with anionic dioleoylphosphatidylglycerol (DOPG), while promoting the formation of nonbilayer structures when mixed with anionic dioleoylphosphatidic acid (DOPA). However, lipoplexes exhibited a virtually identical extent of DNA release when mixed with DOPG or DOPA. Thus, the recently proposed correlation between the formation of nonlamellar phases in lipoplex/anionic lipid mixtures and the increase of DNA release does not seem to exist
Transfection efficiency boost by designer multicomponent lipoplexes
Cationic liposome-DNA complexes (lipoplexes) have emerged as leading nonviral gene carriers in worldwide gene therapy clinical trials. Arriving at therapeutic dosages requires the full understanding of the mechanism of transfection. We investigated the correlation between structural evolution of multicomponent lipoplexes when interacting with cellular lipids, the extent of DNA release and the efficiency in transfecting mouse fibroblast (NIH 3T3), ovarian (CHO) and tumoral myofibroblast-like (A17) cell lines. We show, for the first time, that the transfection pattern increases monotonically with the number of lipid components and further demonstrate by means of synchrotron small angle X-ray scattering (SAXS) that structural changes of lipoplexes induced by cellular lipids correlate with the transfection efficiency. Specifically, inefficient lipoplexes either fused too rapidly upon interaction with anionic lipids or, alternatively, are found to be extremely resistant to solubilization. The most efficient lipoplex formulations exhibited an intermediate behaviour. The extent of DNA unbinding (measured by electrophoresis on agarose gel) correlates with structural evolution of the lipoplexes but DNA-release does not scale with the extent of transfection. The general meaning of our results is of broad interest in the field of non-viral gene delivery: rational adjusting of lipoplex composition to generate the proper interaction between lipoplexes and cellular lipids may be the most appropriate strategy in optimizing synthetic lipid transfection agents
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