3,798 research outputs found
Large-Scale Optical Neural Networks based on Photoelectric Multiplication
Recent success in deep neural networks has generated strong interest in
hardware accelerators to improve speed and energy consumption. This paper
presents a new type of photonic accelerator based on coherent detection that is
scalable to large () networks and can be operated at high (GHz)
speeds and very low (sub-aJ) energies per multiply-and-accumulate (MAC), using
the massive spatial multiplexing enabled by standard free-space optical
components. In contrast to previous approaches, both weights and inputs are
optically encoded so that the network can be reprogrammed and trained on the
fly. Simulations of the network using models for digit- and
image-classification reveal a "standard quantum limit" for optical neural
networks, set by photodetector shot noise. This bound, which can be as low as
50 zJ/MAC, suggests performance below the thermodynamic (Landauer) limit for
digital irreversible computation is theoretically possible in this device. The
proposed accelerator can implement both fully-connected and convolutional
networks. We also present a scheme for back-propagation and training that can
be performed in the same hardware. This architecture will enable a new class of
ultra-low-energy processors for deep learning.Comment: Text: 10 pages, 5 figures, 1 table. Supplementary: 8 pages, 5,
figures, 2 table
De Rham Cohomology of the Supermanifolds and Superstring BRST Cohomology
We show that the BRST operator of Neveu-Schwarz-Ramond superstring is closely
related to de Rham differential on the moduli space of decorated super-Riemann
surfaces P. We develop formalism where superstring amplitudes are computed via
integration of some differential forms over a section of P over the super
moduli space M. We show that the result of integration does not depend on the
choice of section when all the states are BRST physical. Our approach is based
on the geometrical theory of integration on supermanifolds of which we give a
short review.Comment: 6 page
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Injectable diblock copolypeptide hydrogel provides platform to maintain high local concentrations of taxol and local tumor control
Abstract Introduction Surgical resection and systemic chemotherapy with temozolomide remain the mainstay for treatment of glioblastoma. However, many patients are not candidates for surgical resection given inaccessible tumor location or poor health status. Furthermore, despite being first line treatment, temozolomide has only limited efficacy. Methods The development of injectable hydrogel-based carrier systems allows for the delivery of a wide range of chemotherapeutics that can achieve high local concentrations, thus potentially avoiding systemic side effects and wide-spread neurotoxicity. To test this modality in a realistic environment, we developed a diblock copolypeptide hydrogel (DCH) capable of carrying and releasing paclitaxel, a compound that we found to be highly potent against primary gliomasphere cells. Results The DCH produced minimal tissue reactivity and was well tolerated in the immune-competent mouse brain. Paclitaxel-loaded hydrogel induced less tissue damage, cellular inflammation and reactive astrocytes than cremaphor-taxol (typical taxol-carrier) or hydrogel alone. In a deep subcortical xenograft model, of glioblastoma in immunodeficient mice, injection of paclitaxel-loaded hydrogel led to a high local concentration of paclitaxel and led to local tumor control and improved survival. However, the tumor cells were highly migratory and were able to eventually escape the area of treatment. Conclusions These findings suggest this technology may be ultimately applicable to patients with deep-seated inoperable tumors, but as currently formulated, complete tumor eradication would be highly unlikely. Future studies should focus on targeting the migratory potential of surviving cells
Comparing teacher roles in Denmark and England
This article reports the findings of a comparative study of teaching in Denmark and England; its broader aim is to help develop an approach for comparing pedagogy. Lesson observations and interviews identified the range of goals towards which teachers in each country worked and the actions these prompted. These were clustered using the lens of Bernstein’s pedagogic discourse (1990; 1996) to construct teacher roles which provided a view of pedagogy. Through this approach we have begun to identify variations in pedagogy across two countries. All teachers in this study adopted a variety of roles; of significance was the ease with which competent English teachers moved between roles. The English teachers observed adopted roles consistent with a wider techno-rationalist discourse. There was a greater subject emphasis by Danish teachers whose work was set predominantly within a democratic humanist discourse, whilst the English teachers placed a greater emphasis on applied skills
Adaptive Stabilization of a Class of Nonlinear Systems With Nonparametric Uncertainty
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/57794/1/RoupNLAdaptiveTAC2001.pd
The self-referential method for linear rigid bodies : application to hard and Lennard-Jones dumbbells
The self-referential (SR) method incorporating thermodynamic integration (TI) [Sweatman et al., J. Chem. Phys. 128, 064102 (2008)] is extended to treat systems of rigid linear bodies. The method is then applied to obtain the canonical ensemble Helmholtz free energy of the alpha-N2 and plastic face centered cubic phases of systems of hard and Lennard-Jones dumbbells using Monte Carlo simulations. Generally good agreement with reference literature data is obtained, which indicates that the SR-TI method is potentially very general and robust
Study of synthesis parameters and active layer morphology of interfacially polymerized polyamide-polysulfone membranes
Thin film composite (TFC) polyamide membranes were prepared on a polysulfone support membrane and the effect of various synthesis conditions on the active layer morphology, the physicochemical properties and the membrane performance was investigated. The support membrane porosity factor had a significant effect on the TFC membrane performance. A polyamide top layer was formed within 15 s of reaction. Prolonging the reaction time, although resulting in a thicker active layer, only had a minor influence on the membrane performance. This highlights the importance of the incipient layer of the polyamide structure on its performance. The addition of both a surfactant and a base to the amine solution resulted in a change of the active layer morphology and an improved performance. The effect of additives was attributed to changes in the polymerization mechanism. In addition, it was demonstrated that curing at 50°C resulted in an improved membrane performance, due to more cross-linking of the active layer. Curing at higher temperatures deteriorated the structure of the support membrane. This research shows that the TFC membrane performance is well correlated with the changes in the active layer morphology, measured using SEM, AFM and TEM; whereas only minor changes in the physicochemical characteristics of the membranes were detected by zeta potential and ATR-FTIR spectroscopy when the same synthesis parameters were varied.status: publishe
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