1,250,058 research outputs found
D-brane categories
This is an exposition of recent progress in the categorical approach to
D-brane physics. I discuss the physical underpinnings of the appearance of
homotopy categories and triangulated categories of D-branes from a string field
theoretic perspective, and with a focus on applications to homological mirror
symmetry.Comment: 37 pages, IJMPA styl
Light controlled photon tunneling
Recent measurements of photon tunneling through individual subwavelength
pinholes in a gold film covered with a layer of polydiacetylene (Phys. Rev.
Letters 88, 187402 (2002)) provided strong indication of "photon blockade"
effect similar to Coulomb blockade phenomenon observed in single-electron
tunneling experiments. Here we report first observation of photon tunneling
been blocked (gated) by light at a different wavelength. This observation
suggests possibility of building new class of photon tunneling gating devices
for all-optical signal processing.Comment: 11 pages, 3 figure
Magnifying superlens in the visible frequency range
In this communication we introduce a new design of the magnifying superlens
and demonstrate it in the experiment.Comment: 3pages, 1 figur
Far-field optical microscope with nanometer-scale resolution based on in-plane surface plasmon imaging
A new far-field optical microscopy technique capable of reaching
nanometer-scale resolution has been developed recently using the in-plane image
magnification by surface plasmon polaritons. This microscopy is based on the
optical properties of a metal-dielectric interface that may, in principle,
provide extremely large values of the effective refractive index n up to
100-1000 as seen by the surface plasmons. Thus, the theoretical diffraction
limit on resolution becomes lambda/2n, and falls into the nanometer-scale
range. The experimental realization of the microscope has demonstrated the
optical resolution better than 50 nm for 502 nm illumination wavelength.
However, the theory of such surface plasmon-based far-field microscope
presented so far gives an oversimplified picture of its operation. For example,
the imaginary part of the metal dielectric constant severely limits the
surface-plasmon propagation and the shortest attainable wavelength in most
cases, which in turn limits the microscope magnification. Here I describe how
this limitation has been overcome in the experiment, and analyze the practical
limits on the surface plasmon microscope resolution. In addition, I present
more experimental results, which strongly support the conclusion of extremely
high spatial resolution of the surface plasmon microscope.Comment: 23 pages, 9 figures, will be published in the topical issue on
Nanostructured Optical Metamaterials of the Journal of Optics A: Pure and
Applied Optics, Manuscript revised in response to referees comment
Increasing transmission efficiency with advanced signal processing
Optical CDMA is an advanced and flexible communication technology with a potential to offer very energy efficient and highly scalable networking. In addition it can also deliver increased physical layer privacy and on-demand bandwidth sharing management. We have developed, extensively investigated, and experimentally demonstrated highly scalable approach to incoherent OCDMA which can very efficiently increase the number of simultaneous users. In addition, the introduction of an advanced photonic signal processing results in an overall system power budget improvement by nearly 3dB. Error-free operation with the BER less than 10-12 was achieved. We have also shown that with demonstrated approach we can dramatically improve number of simultaneous network users (up to ten times) while keeping the related hardware count unchanged. By comparing this results to DWDM concept, this substantial increase in number of simultaneous users did not require to add any additional wavelength laser sources and was achieved by employing just three communication wavelengths
Generalized complexes and string field theory
I discuss the axiomatic framework of (tree-level) associative open string
field theory in the presence of D-branes by considering the natural extension
of the case of a single boundary sector. This leads to a formulation which is
intimately connected with the mathematical theory of differential graded
categories. I point out that a generic string field theory as formulated within
this framework is not closed under formation of D-brane composites and as such
does not allow for a unitary description of D-brane dynamics. This implies that
the collection of boundary sectors of a generic string field theory with
D-branes must be extended by inclusion of all possible D-brane composites. I
give a precise formulation of a weak unitarity constraint and show that a
minimal extension which is unitary in this sense can always be obtained by
promoting the original D-brane category to an enlarged category constructed by
using certain generalized complexes of D-branes. I give a detailed construction
of this extension and prove its closure under formation of D-brane composites.
These results amount to a completely general description of D-brane composite
formation within the framework of associative string field theory.Comment: 31 pages, 4 figures; v2: small typos corrected, changed to JHEP styl
Cancer Clinical Trials Optimization and Pharmacogenomics
A critical overview of recent clinical trials in cancer is presented focused on signaling pathways blockers or inhibitors with a view to developing successful clinical trials employing personalized cancer therapies. Rational, pharmacogenomic strategies in cancer trials should be adopted that include specific molecular targeting based on adequate data for, and detailed modeling of, cancer cell genomes, modifications of cancer signaling pathways and epigenetic mechanisms. Novel translational oncogenomics research is rapidly expanding through the application of highly sensitive and specific advanced technology, research findings and computational tools and complex models to both pharmaceutical and clinical problems. Multiple sample analyses from several recent clinical studies have shown that gene expression data for cancer cells can be employed to distinguish between tumor types as well as to predict outcomes. Potentially important applications of such results are individualized human cancer therapies or, in general,'personalized medicine' that will have to be validated through optimally designed clinical trials in cancer. A Human Cancer Genomes and Epigenetics Project is proposed that can provide the essential data required for the optimal design of clinical trials with the goal of achieving significant improvements of the survival rates of cancer patients participating in clinical trials for advanced cancer stages. The results of such a six-year Human Cancer Genomes and Epigenetics Project should also greatly aid with the accelerated, rational development of effective anti-cancer medicines and the chemoprevention of cancers
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The Historical Role of the European Shadow Banking System in the Development and Evolution of Our Monetary Institutions
When we hear about the 2008 Lehman Brothers crisis, immediately we relate it to the concept of "shadow banking system"; however, the credit intermediation involving lightly regulated entities and activities outside the traditional banking system are not new for the European Financial Systems, after all, many innovations developed in the past, were adopted by European nations and exported to the rest of the world (i.e. coinage and central banking), and European innovators unleashed several financial crises related to "shadowy" financial intermediaries (i.e. the Gebroeders de Neufville crisis of 1763). However, despite not many academics, legislators and regulators even agree on what "shadow banking" is, this latter does not refer exclusively to the functions of credit intermediation and maturity transformation. This concept also refers to the creation of assets such as digital media of exchange which are designed under the influence of Friedrich Hayek and the Austrian School of Economics. This lack of a uniform definition of "shadow banking" has limited our regulatory efforts on key issues like the private money creation, a source of vulnerability in the financial system that, paradoxically, at the same time could result in an opportunity to renovate European institutions, heirs of the tradition of the Wisselbank and the Bank of England which, during the seventeenth century, faced monetary innovations and led the European monetary revolution that originated the current monetary and regulatory practices implemented around the world
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