Frequency-multiplexed and pipelined iterative optical systolic array processors

Optical matrix processors using acoustooptic transducers are described with emphasis on new systolic array architectures using frequency multiplexing in addition to space and time multiplexing. A Kalman filtering application is considered as our case study from which the operations required on such a system can be defined. This also serves as a new and powerful application for iterative optical processors. The importance of pipelining the data flow and the ordering of the operations performed in a specific application of such a system are also noted. Several examples of how to effectively achieve this are included. A new technique for handling bipolar data on such architectures is also described.     

Al Mansfeld and the interpretation of the Israel Museum

Over the past few decades, the Israel Museum in Jerusalem has been the subject of post-colonial interpretations which likened the organisation of the pavilions that make up the museum to the form of an Arab village. Focusing on the organisational and formal similarities between the museum and the typology of the Arab village, these interpretations propose that Israel, even before the 1967 War and the conquest of the West Bank and Gaza Strip, had already begun to appropriate Palestinian symbols. These interpretations often refer to drawings made by Al Mansfeld, the museum's architect. This essay argues that while the post-colonial interpretations may be correct, they neglect to address yet another big influence on Mansfeld's thinking when he conceptualised the Israel Museum in the late 1950s. During the early 1930s in Berlin, Mansfeld was a student of two German Expressionist architects, Hans Poelzig and Heinrich Tessenow. During these years, Mansfeld was exposed to expressionist ideas about architecture that later permeated his designs and artwork, including the design of the Israel Museum.     

Mixed explicit-implicit iterative finite element scheme for diffusion-type problems: II. Solution strategy and examples

In Part I¹ of this paper we have established local stability and convergence criteria for the mixed explicit-implicit finite element scheme and have shown that the proposed iterative method converges under certain conditions. Part II describes various practical aspects of the solution strategy such as convergence criteria for terminating the iterations, automatic control of time step size, reclassification of nodes from explicit to implicit during execution, estimation of time derivatives, and automatic adjustment of the implicit weight factor. Several examples are included to demonstrate certain aspects of the theory and illustrate the capabilities of the new approach.     

Optical trapping

Since their invention just over 20 years ago, optical traps have emerged as a powerful tool with broad-reaching applications in biology and physics. Capabilities have evolved from simple manipulation to the application of calibrated forces on-and the measurement of nanometer-level displacements of-optically trapped objects. We review progress in the development of optical trapping apparatus, including instrument design considerations, position detection schemes and calibration techniques, with an emphasis on recent advances. We conclude with a brief summary of innovative optical trapping configurations and applications.     

The Image of the Institution

Despite the dramatic tales of woe, deficiencies in the nation's infrastructure - the capital stock of state and local governments - are not universal, but concentrated regionally and within regions. The only evidence of widespread and systematic under-investment is for highways. That is a result of the structure of state highway finance systems, aversion to tax rate increases at the state level, and the lack of coherent replacement strategies by almost all government units in the country. The consequences of infrastructure deficiencies are almost entirely local, rather than national. A national infrastructure policy is neither necessary nor desirable.     

Photo-displacement imaging

A modulated laser beam, incident on a surface, gives rise to a time-varying surface displacement. This displacement can be detected by means of a laser interferometer, thereby forming the basis for a novel imaging system. Preliminary results to demonstrate the viability of such a technique are presented.     

Alternative Promoter Use Governs the Expression of IgLON Cell Adhesion Molecules in Histogenetic Fields of the Embryonic Mouse Brain

The members of the IgLON superfamily of cell adhesion molecules facilitate fundamental cellular communication during brain development, maintain functional brain circuitry, and are associated with several neuropsychiatric disorders such as depression, autism, schizophrenia, and intellectual disabilities. Usage of alternative promoter-specific 1a and 1b mRNA isoforms in Lsamp, Opcml, Ntm, and the single promoter of Negr1 in the mouse and human brain has been previously described. To determine the precise spatiotemporal expression dynamics of Lsamp, Opcml, Ntm isoforms, and Negr1, in the developing brain, we generated isoform-specific RNA probes and carried out in situ hybridization in the developing (embryonic, E10.5, E11.5, 13.5, 17; postnatal, P0) and adult mouse brains. We show that promoter-specific expression of IgLONs is established early during pallial development (at E10.5), where it remains throughout its differentiation through adulthood. In the diencephalon, midbrain, and hindbrain, strong expression patterns are initiated a few days later and begin fading after birth, being only faintly expressed during adulthood. Thus, the expression of specific IgLONs in the developing brain may provide the means for regionally specific functionality as well as for specific regional vulnerabilities. The current study will therefore improve the understanding of how IgLON genes are implicated in the development of neuropsychiatric disorders.     

mPEG–NHS carbonates: Effect of alkyl spacers on the reactivity: Kinetic and mechanistic insights

Nowadays, the chemical conjugation to mPEG, also known as PEGylation, is a well-recognized technology used to improve the pharmaceutical properties of the therapeutic proteins. Over the last 20 years, more than 10 PEGylated macromolecules reached the market with tremendous success, whereas various other bioconjugates are under advanced clinical trials. mPEG–N-hydroxysuccinimidyl carbonate is an important reagent of widespread application for the PEGylation of biomacromolecules. One of the most important challenges in this technology is the development of more selective PEGylation reagents aimed to provide more consistent polymer–protein conjugates. One approach followed to improve the selectivity of PEGylation reagents is the design of less reactive derivatives, for example, by incorporation of alkyl spacers between the polymer chain and the terminal reactive group. In this work, we prepared a family of mPEG–N-hydroxysuccinimidyl carbonates bearing spacers of up to 6 carbon atoms. The kinetics of hydrolysis of the carbonates was studied under different experimental conditions, as a straight measure of the influence of the length of the spacer on the reactivity. By DFT calculations, we propose a detailed mechanism for the hydrolysis reaction. The influence of the length of alkyl spacer on the reactivity of the carbonates and related esters is studied and discussed in detail. Finally, to further evaluate the reactivity, selected N-hydroxysuccinimidyl carbonates were studied in the conjugation reaction of bovine lactoferrin. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47028.     

Elevated temperature electrical resistivity measurements of zirconium diboride using the van der Pauw Method

A novel electrical testing assembly was designed, fabricated, and validated to allow elevated temperature electrical resistivity measurements using the van der Pauw method up to 2173 K. The assembly consisted of h-BN insulators, ZrB₂-based fixture components, and W signal wires. The assembly was installed in a refractory metal element furnace for temperature control and an oxygen gettering system was utilized to control the oxygen activity of the process gas. The system was validated using high-purity Mo as a reference standard, demonstrating good agreement with accepted electrical resistivity values for Mo. The system was utilized to measure the electrical resistivity of a ZrB₂ ceramic that was produced from commercially available ZrB₂ powder using C and ZrH₂ as sintering aids and densified by hot-pressing at 2423 K. The resulting ZrB₂ ceramic was ~96% dense with ~0.2 wt.% ZrO₂ secondary phase and a grain size of ~40 µm. Electrical resistivity of ZrB₂ was measured from room temperature to 2133 K. The electrical resistivity of the ZrB₂ exhibited distinct linear behavior with respect to temperature, increasing from 7.3 µΩ-cm at 298 K to 35.7 µΩ-cm at 1223 K (~0.031 µΩ-cm/K), and then further increasing to 76.0 µΩ-cm at 2133 K (~0.044 µΩ-cm/K). To the knowledge of the authors, these measurements were performed at the highest temperatures ever reported using this method.     

Titanium diboride–silicon carbide–boron carbide ceramics with super‐high hardness and strength

Triplex particulate composites composed of boride and carbide ceramics were found to have high strength, hardness, and fracture toughness values. Two compositions consisting of 70:15:15 and 1:1:1 volume ratios of TiB_2, SiC, and B₄C were produced from commercially available powders by hot‐pressing. The 70:15:15 ceramic exhibited a strength of ~1.3 GPa, while the 1:1:1 ceramic had a strength of ~0.9 GPa. These strengths are comparable to super‐strong Y₂O₃‐PSZ and β‐SiAlON based composites. The Vickers’ hardness values of these ceramics were ~32 GPa for indent loads of 9.8 N. Hardness increased as indentation load decreased. The 1:1:1 ceramic had a hardness of ~53 GPa at an indentation load of 0.49 N, higher than values reported for so‐called “super‐hard” ceramics, and comparable to c‐BN.