5,222 research outputs found
CoAP Infrastructure for IoT
The Internet of Things (IoT) can be seen as a large-scale network of billions of smart devices. Often IoT
devices exchange data in small but numerous messages, which requires IoT services to be more scalable and
reliable than ever. Traditional protocols that are known in the Web world does not fit well in the constrained
environment that these devices operate in. Therefore many lightweight protocols specialized for the IoT have
been studied, among which the Constrained Application Protocol (CoAP) stands out for its well-known REST
paradigm and easy integration with existing Web. On the other hand, new paradigms such as Fog Computing
emerges, attempting to avoid the centralized bottleneck in IoT services by moving computations to the edge
of the network. Since a node of the Fog essentially belongs to relatively constrained environment, CoAP fits
in well. Among the many attempts of building scalable and reliable systems, Erlang as a typical concurrency-oriented programming (COP) language has been battle tested in the telecom industry, which has similar requirements
as the IoT. In order to explore the possibility of applying Erlang and COP in general to the IoT, this thesis
presents an Erlang based CoAP server/client prototype ecoap with a flexible concurrency model that can
scale up to an unconstrained environment like the Cloud and scale down to a constrained environment like
an embedded platform. The flexibility of the presented server renders the same architecture applicable from
Fog to Cloud. To evaluate its performance, the proposed server is compared with the mainstream CoAP
implementation on an Amazon Web Service (AWS) Cloud instance and a Raspberry Pi 3, representing the
unconstrained and constrained environment respectively. The ecoap server achieves comparable throughput,
lower latency, and in general scales better than the other implementation in the Cloud and on the Raspberry
Pi. The thesis yields positive results and demonstrates the value of the philosophy of Erlang in the IoT space
Minimal sets determining universal and phase-covariant quantum cloning
We study the minimal input sets which can determine completely the universal
and the phase-covariant quantum cloning machines. We find that the universal
quantum cloning machine, which can copy arbitrary input qubit equally well,
however can be determined completely by only four input states located at the
four vertices of a tetrahedron. The phase-covariant quantum cloning machine,
which can copy all qubits located on the equator of the Bloch sphere, can be
determined by three equatorial qubits with equal angular distance. These
results sharpen further the well-known results that BB84 states and six-states
used in quantum cryptography can determine completely the phase-covariant and
universal quantum cloning machines. This concludes the study of the power of
universal and phase-covariant quantum cloning, i.e., from minimal input sets
necessarily to full input sets by definition. This can simplify dramatically
the testing of whether the quantum clone machines are successful or not, we
only need to check that the minimal input sets can be cloned optimally.Comment: 7 pages, 4 figure
Fluorescence in situ hybridization mapping of the cystic fibrosis transmembrane conductance regulator (CFTR) gene to 7q31.3
We have used the fluorescence in situ hybridization (FISH) technique to refine the localization of the cystic fibrosis transmembrane conductance regulator (CFTR) gene on human chromosome 7. The result shows that the gene is most likely located within band q31.3.published_or_final_versio
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