2,902 research outputs found
Both doublecortin and doublecortin-like kinase play a role in cortical interneuron migration
Type I lissencephaly, a genetic disease characterized by disorganized cortical layers and gyral abnormalities, is associated with severe cognitive impairment and epilepsy. Two genes, LIS1 and doublecortin (DCX), have been shown to be responsible for a large proportion of cases of type I lissencephaly. Both genes encode microtubule-associated proteins that have been shown to be important for radial migration of cortical pyramidal neurons. To investigate whether DCX also plays a role in cortical interneuron migration, we inactivated DCX in the ganglionic eminence of rat embryonic day 17 brain slices using short hairpin RNA. We found that, when DCX expression was blocked, the migration of interneurons from the ganglionic eminence to the cerebral cortex was slowed but not absent, similar to what had previously been reported for radial neuronal migration. In addition, the processes of DCX-deficient migrating interneurons were more branched than their counterparts in control experiments. These effects were rescued by DCX overexpression, confirming the specificity to DCX inactivation. A similar delay in interneuron migration was observed when Doublecortin-like kinase (DCLK), a microtubule-associated protein related to DCX, was inactivated, although the morphology of the cells was not affected. The importance of these genes in interneuron migration was confirmed by our finding that the cortices of Dcx, Dclk, and Dcx/Dclk mutant mice contained a reduced number of such cells in the cortex and their distribution was different compared with wild-type controls. However, the defect was different for each group of mutant animals, suggesting that DCX and DCLK have distinct roles in cortical interneuron migration
Local Voids as the Origin of Large-angle Cosmic Microwave Background Anomalies: The Effect of a Cosmological Constant
We explore the large angular scale temperature anisotropies in the cosmic
microwave background (CMB) due to homogeneous local dust-filled voids in a flat
Friedmann-Robertson-Walker universe with a cosmological constant. In comparison
with the equivalent dust-filled void model in the Einstein-de Sitter
background, we find that the anisotropy for compensated asymptotically
expanding local voids can be larger because second-order effects enhance the
linear integrated Sachs-Wolfe (ISW) effect. However, for local voids that
expand sufficiently faster than the asymptotic velocity of the wall, the
second-order effect can suppress the fluctuation due to the linear ISW effect.
A pair of quasi-linear compensated asymptotic local voids with radius
(2-3)*10^2 ~h^{-1} Mpc and a matter density contrast ~-0.3 can be observed as
cold spots with a temperature anisotropy Delta T/T~O(10^{-5}) that might help
explain the observed large-angle CMB anomalies. We predict that the associated
anisotropy in the local Hubble constant in the direction of the voids could be
as large as a few percent.Comment: 23 pages, 5 figures, version accepted for publication in ApJ with
minor revisio
Angular dependence of the emission wavelength in microactivity organic light-emitting diodes
In this work, we have calculated the emission wavelength dependence on the viewing angle for different combinations of metallic mirrors. The dispersion of the optical functions of ten different metals is fully taken into account using Lorentz oscillator model. The metals have been assigned to a function of top (cathode) or bottom (anode) mirror based on their work function. Refractive index dispersion of organic layers, N,N'-disphenyl-N,N'-bis(3-methylphenyl)-1,1'-disphenyl-4,4'-diamine (TPD) and tris (8-hydroxyquinoline) aluminum (emitting layer) is taken into account via Cauchy model. The change of the emission wavelength with angle has been calculated iteratively-to fully take into account wavelength dependence of indices of refraction and phase change. Calculations have been performed for different hole transport materials and different thickness of the emitting layer
A Comparison of Small Signal Modulation Parameter Extraction Techniques for Vertical-Cavity, Surface-Emitting Lasers
The small signal modulation characteristics of a vertical-cavity, surface-emitting laser (VCSEL) are determined using three different measurements: relative intensity noise, frequency response, and high resolution optical spectra. The resonant and damping frequencies were measured, and related rate equation parameters were extracted; excellent agreement was found both between experiment and theory, and amongst the different measurement techniques. The results and procedures are compared, and the findings are presented below
Digital twin control of multi-axis wood CNC machining center based on LinuxCNC
Abstrack:
This paper presents an application of an open architecture control system implemented on a multi-axis wood computer numerical control milling machining center, as a digital twin control. The development of the digital twin control system was motivated by research and educational requirements, especially in the field of configuring a new control system by “virtual commissioning”, enabling the validation of the developed controls, program verification, and analysis of the machining process and monitoring. The considered wood computer numerical control (CNC) machining system is supported by an equivalent virtual machine in a computer-aided design and computer-aided manufacturing (CAD/CAM) environment, as well as in the control system, as a digital twin. The configured virtual machines are used for the verification of the machining program and programming system via machining simulation, which is extremely important in multi-axis machining. Several test wood workpieces were machined to validate the effectiveness of the developed control system based on LinuxCNC
Digital Servitization and Firm Performance: Technology Intensity Approach
Digital servitization provides radical changes in the offer of products from manufacturing firms. The purpose of this paper is to investigate the impact of digital servitization on manufacturing firm performance and demonstrate the role of technology intensity, product-related services, and digital solutions in different industry sectors. This research collected data from 240 manufacturing firms from the Republic of Serbia under the European manufacturing survey from 2018. Multivariate regression analysis was used to test the impact of product-related services and digital solutions on manufacturing firm performance according to technology intensity. The findings show that the impact of digital servitization is more significant with the higher technology intensity level of the industry sector. Furthermore, the results show that Data-based services based on Big Data Analysis have the highest impact on manufacturing firm performance in all categories of technology intensity. Moreover, results from the fixed panel regression show production managers which combination of product-related services along with digital solutions make the highest financial performance according to the technology intensity of the firm
Local Voids as the Origin of Large-angle Cosmic Microwave Background Anomalies I
We explore the large angular scale temperature anisotropies in the cosmic
microwave background due to expanding homogeneous local voids at redshift z~1.
A compensated spherically symmetric homogeneous dust-filled void with radius
\~3*10^2 h^{-1}Mpc, and density contrast ~-0.3 can be observed as a cold spot
with a temperature anisotropy -1*10^{-5} surrounded by a slightly hotter ring.
We find that a pair of these circular cold spots separated by ~50 degree can
account both for the planarity of the octopole and for the alignment between
the quadrupole and the octopole in the cosmic microwave background (CMB)
anisotropy. The cold spot in the Galactic southern hemisphere which is
anomalous at the ~3sigma level can be explained by such a large void at z~1.
The observed north-south asymmetry in the large-angle CMB power can be
attributed to the asymmetric distribution of these local voids between the two
hemispheres. The statistical significance of the low quadrupole is further
reduced in this interpretation of the large angular scale CMB anomalies.Comment: 8 pages, 5 eps files, Version accepted for ApJ. New maps for
non-overlapping voids (Fig. 4) is adde
The mechanism of caesium intercalation of graphene
Properties of many layered materials, including copper- and iron-based
superconductors, topological insulators, graphite and epitaxial graphene can be
manipulated by inclusion of different atomic and molecular species between the
layers via a process known as intercalation. For example, intercalation in
graphite can lead to superconductivity and is crucial in the working cycle of
modern batteries and supercapacitors. Intercalation involves complex diffusion
processes along and across the layers, but the microscopic mechanisms and
dynamics of these processes are not well understood. Here we report on a novel
mechanism for intercalation and entrapment of alkali-atoms under epitaxial
graphene. We find that the intercalation is adjusted by the van der Waals
interaction, with the dynamics governed by defects anchored to graphene
wrinkles. Our findings are relevant for the future design and application of
graphene-based nano-structures. Similar mechanisms can also play a role for
intercalation of layered materials.Comment: 8 pages, 7 figures in published form, supplementary information
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