3,457 research outputs found
Towards feasible, machine-assisted verification of object-oriented programs
This thesis provides an account of a development of tools towards making verification of object-oriented programs more feasible. We note that proofs in program verification logics are typically long, yet, mathematically, not very deep; these observations suggest the thesis that computers can significantly ease the burden of program verification. We give evidence supporting this by applying computers to (1) automatically check and (2) automatically infer large parts of proofs. Taking the logic (AL) of Abadi and Leino as our starting point, we initially show how the logic can be embedded into a higher-order logic theorem prover, by way of introducing axioms, using a mix of both higher-order abstract syntax (HOAS) and a direct embedding of the assertion logic. The tenacity and exactness of the theorem prover ensures that no proof obligation is inadvertently lost during construction of a proof; we inherit any automatic facilities such as tactics which take us part way towards goal (2); and moreover, we achieve goal (1), since we inherit machine proofs which can be checked automatically. We present som
Semantic Augmented Reality Environment with Material-Aware Physical Interactions
© 2017 IEEE. In Augmented Reality (AR) environment, realistic interactions between the virtual and real objects play a crucial role in user experience. Much of recent advances in AR has been largely focused on developing geometry-aware environment, but little has been done in dealing with interactions at the semantic level. High-level scene understanding and semantic descriptions in AR would allow effective design of complex applications and enhanced user experience. In this paper, we present a novel approach and a prototype system that enables the deeper understanding of semantic properties of the real world environment, so that realistic physical interactions between the real and the virtual objects can be generated. A material-aware AR environment has been created based on the deep material learning using a fully convolutional network (FCN). The state-of-the-art dense Simultaneous Localisation and Mapping (SLAM) has been used for the semantic mapping. Together with efficient accelerated 3D ray casting, natural and realistic physical interactions are generated for interactive AR games. Our approach has significant impact on the future development of advanced AR systems and applications
A Ly-alpha nebula at z~3.3
Context. Searching for high-redshift galaxies is a field of intense activity
in modern observational cosmology that will continue to grow with future
ground-based and sky observatories. Over the last few years, a lot has been
learned about the high-z Universe. Aims. Despite extensive Ly-alpha Blobs (LAB)
surveys from low to high redshifts, giant LABs over 100 kpc have been found
mostly at z~2-4. This redshift range is coincident with the transition epoch of
galactic gas-circulation processes from inflows to outflows at z~2.5-3. This
suggests that the formation of giant LABs may be related to a combination of
gas inflows and outflows. Their extreme youth makes them interesting objects in
the study of galaxy formation as they provide insight into some of the youngest
known highly star forming galaxies, with only modest time investments using
ground-based telescopes. Methods. Systematic narrow-band Ly-alpha nebula
surveys are ongoing, but they are limited in their covered redshift range and
their comoving volume. This poses a significant problem when searching for such
rare sources. To address this problem, we developed a systematic searching
tool, ATACAMA (A Tool for seArChing for lArge LyMan Alpha nebulae) designed to
find large Ly-alpha nebulae at any redshift within deep multi-wavelength
broad-band imaging. Results. We identified a Ly-alpha nebula candidate at
zphot~3.3 covering an isophotal area of 29.4sq.arcsec. Its morphology shows a
bright core and a faint core which coincides with the morphology of previously
known Ly-alpha blobs. A first estimation of the Ly-alpha equivalent width and
line flux agree with the values from the study led by several groups.Comment: Accepted to A&A, 8 pages, 4 figures. arXiv admin note: text overlap
with arXiv:1708.00447 by other author
Large magnetoresistance at room-temperature in small molecular weight organic semiconductor sandwich devices
We present an extensive study of a large, room temperature negative
magnetoresistance (MR) effect in tris-(8-hydroxyquinoline) aluminum sandwich
devices in weak magnetic fields. The effect is similar to that previously
discovered in polymer devices. We characterize this effect and discuss its
dependence on field direction, voltage, temperature, film thickness, and
electrode materials. The MR effect reaches almost 10% at fields of
approximately 10 mT at room temperature. The effect shows only a weak
temperature dependence and is independent of the sign and direction of the
magnetic field. Measuring the devices' current-voltage characteristics, we find
that the current depends on the voltage through a power-law. We find that the
magnetic field changes the prefactor of the power-law, whereas the exponent
remains unaffected. We also studied the effect of the magnetic field on the
electroluminescence (MEL) of the devices and analyze the relationship between
MR and MEL. We find that the largest part of MEL is simply a consequence of a
change in device current caused by the MR effect.Comment: 8 figure
Rest-Katyusha: Exploiting the Solution's Structure via Scheduled Restart Schemes
We propose a structure-adaptive variant of the state-of-the-art stochastic
variance-reduced gradient algorithm Katyusha for regularized empirical risk
minimization. The proposed method is able to exploit the intrinsic
low-dimensional structure of the solution, such as sparsity or low rank which
is enforced by a non-smooth regularization, to achieve even faster convergence
rate. This provable algorithmic improvement is done by restarting the Katyusha
algorithm according to restricted strong-convexity constants. We demonstrate
the effectiveness of our approach via numerical experiments
Measurement of teicoplanin by liquid chromatography-tandem mass spectrometry:development of a novel method
Teicoplanin is an antibiotic used for the treatment of endocarditis, osteomyelitis, septic arthritis and methicillin-resistant Staphylococcus aureus. Teicoplanin is emerging as a suitable alternative antibiotic to vancomycin, where their trough serum levels are monitored by immunoassay routinely. This is the first report detailing the development of a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for measuring teicoplanin in patients' serum
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