A generative network model of neurodevelopmental diversity in structural brain organization.

The formation of large-scale brain networks, and their continual refinement, represent crucial developmental processes that can drive individual differences in cognition and which are associated with multiple neurodevelopmental conditions. But how does this organization arise, and what mechanisms drive diversity in organization? We use generative network modeling to provide a computational framework for understanding neurodevelopmental diversity. Within this framework macroscopic brain organization, complete with spatial embedding of its organization, is an emergent property of a generative wiring equation that optimizes its connectivity by renegotiating its biological costs and topological values continuously over time. The rules that govern these iterative wiring properties are controlled by a set of tightly framed parameters, with subtle differences in these parameters steering network growth towards different neurodiverse outcomes. Regional expression of genes associated with the simulations converge on biological processes and cellular components predominantly involved in synaptic signaling, neuronal projection, catabolic intracellular processes and protein transport. Together, this provides a unifying computational framework for conceptualizing the mechanisms and diversity in neurodevelopment, capable of integrating different levels of analysis-from genes to cognition

Photonic band gap structures for WDM applications

A new structure by combining a single cavity and coupled-cavity waveguides (CCWs) for wavelength division multiplexing (WDM) applications was proposed. As such, a structure in which the coupling between the cavity mode and the guiding model allows to drop a selective wavelength λi was designed. The selectivity of dropping wavelength was determined by local properties of the cavity modes. Such results were said to be important for designing future ultrasmall optical circuits

Building artificial neural circuits for domain-general cognition: a primer on brain-inspired systems-level architecture

There is a concerted effort to build domain-general artificial intelligence in the form of universal neural network models with sufficient computational flexibility to solve a wide variety of cognitive tasks but without requiring fine-tuning on individual problem spaces and domains. To do this, models need appropriate priors and inductive biases, such that trained models can generalise to out-of-distribution examples and new problem sets. Here we provide an overview of the hallmarks endowing biological neural networks with the functionality needed for flexible cognition, in order to establish which features might also be important to achieve similar functionality in artificial systems. We specifically discuss the role of system-level distribution of network communication and recurrence, in addition to the role of short-term topological changes for efficient local computation. As machine learning models become more complex, these principles may provide valuable directions in an otherwise vast space of possible architectures. In addition, testing these inductive biases within artificial systems may help us to understand the biological principles underlying domain-general cognition.Comment: This manuscript is part of the AAAI 2023 Spring Symposium on the Evaluation and Design of Generalist Systems (EDGeS

Enhanced transmission of microwave radiation in one-dimensional metallic gratings with subwavelength aperture

We report a theoretical and experimental demonstration of enhanced microwave transmission through subwavelength apertures in metallic structures with double-sided gratings. Three different types of aluminum gratings (sinusoidal, symmetric rectangular, and asymmetric rectangular shaped) are designed and analyzed. Our samples have a periodicity of 16 mm, and a slit width of 2 mm. Transmission measurements are taken in the 10–37.5 GHz frequency spectrum, which corresponds to 8–30 mm wavelength region. All three structures display significantly enhanced transmission around surface plasmon resonance frequencies. The experimental results agree well with finite-difference-time-domain based theoretical simulations. Asymmetric rectangular grating structure exhibits the best results with ,50% transmission at 20.7 mm, enhancement factor of ,25, and ±4° angular divergence

Resonant excitation of surface plasmons in one-dimensional metallic grating structures at microwave frequencies

Grating-coupling phenomena between surface plasmons and electromagnetic waves were studied in the microwave spectrum using metallic gratings. Transmission measurements were carried out to observe the transmitted radiation around the surface plasmon resonance frequencies. Grating structures with subwavelength apertures were designed for transmission experiments. Measurements were made in the microwave spectrum of 10-37.5 GHz, corresponding to a wavelength region of 8-30 mm. The A1 samples had a grating periodicity of 16 mm. A 2 mm wide subwavelength slit was opened for transmission samples. Samples with one/double-sided gratings displayed remarkably enhanced transmission and directivity with respect to the reference sample without gratings. The experimental results agreed well with theoretical simulations. ∼50% transmission at 20.7 mm, ∼25-fold enhancement, and ±4° angular divergence were achieved with a ∼λ/10 aperture. © 2005 IOP Publishing Ltd

Growth and characterization of SiC epitaxial layers on Si- and C-face 4H SiC substrates by chemical-vapor deposition

High-quality Schottky junctions have been fabricated on n-type 4H SiC epitaxial layers grown by chemical-vapor deposition on C- and Si-face substrates in order to understand the effect of growth direction on the growth mechanism and formation of defects. Atomic force microscopy analysis showed dramatic differences between the surfaces of SiC epilayers grown on C and Si faces. There was a significant step bunching in the SiC grown on Si-face substrates. Current-voltage, capacitance-voltage, and deep-level transient spectroscopy (DLTS) measurements were carried out on the Schottky junctions to analyze the junction characteristics. The Schottky junctions on C-face SiC showed larger barrier heights than those on Si-face SiC, showing that each face has a different surface energy. The barrier heights of Ni Schottky junctions were found to be 1.97 and 1.54 eV for C-face and Si-face materials, respectively. However, the deep-level spectra obtained by DLTS were similar, regardless of the increased surface roughness of the Si-face 4H SiC

Effect of C∕Si ratio on deep levels in epitaxial 4H–SiC

Changing the ratio of carbon to silicon during the epitaxial 4H–SiC growth is expected to alter the dominant deep level trap, which has been attributed to a native defect. The C∕Si ratio was changed from one to six during epitaxialgrowth of SiC. Diodes fabricated on the epitaxial layer were then characterized using current-voltage and deep level transient spectroscopy. The single peak at 340K (Z1/Z2 peak), was deconvolved into two traps, closely spaced in energy. The concentration of one of the Z1/Z2 traps decreased with increasing C∕Si ratio. This result opposes theoretical predictions of carboninterstitial components, and supports assignment to a silicon antisite or carbonvacancy relationship. The concentration of the second component of the peak at 340K did not depend on the C∕Si ratio, which would indicate an impurity in an interstitial site

Functional immune characterization of HIV-associated non-small-cell lung cancer.

Dear Editor, In the combined anti-retroviral therapy (cART) era, non-small cell lung cancer (NSCLC) is a highly incident cause of morbidity and mortality in people living with HIV (PLHIV)[1]. The immune-pathogenesis of NSCLC and HIV infection both rely on programmed-death 1 (PD-1) receptor-ligand interaction as a mechanism to induce T-cell exhaustion. To date, PLHIV have been excluded from clinical trials of immune-checkpoint inhibitors (ICPI), on the presumption that anti-tumour immunity might be compromised by HIV infection. To verify this, we evaluated the clinico-pathologic significance of PD-ligands expression in a consecutive series of 221 archival NSCLC samples, 24 of which were HIV-associated (Table S1)