2,830 research outputs found
Technological trends affecting the manufacturing sector of New York City
The author concludes that manufacturing is still a vital part of New York City's economy, despite substantial job losses in this sector over the past two decades. An influx of skilled immigrants, the use of advanced technologies in production processes, and the ability to respond rapidly to global markets give New York City a strong future in manufacturing high-value goods.New York (N.Y.) ; Technology ; Federal Reserve District, 2nd
Stage-Specific Timing of the microRNA Regulation of \u3cem\u3elin-28\u3c/em\u3e by the Heterochronic Gene \u3cem\u3elin-14\u3c/em\u3e in \u3cem\u3eCaenorhabditis elegans\u3c/em\u3e
In normal development, the order and synchrony of diverse developmental events must be explicitly controlled. In the nematode Caenorhabditis elegans, the timing of larval events is regulated by hierarchy of proteins and microRNAs (miRNAs) known as the heterochronic pathway. These regulators are organized in feedforward and feedback interactions to form a robust mechanism for specifying the timing and execution of cell fates at successive stages. One member of this pathway is the RNA binding protein LIN-28, which promotes pluripotency and cell fate decisions in successive stages. Two genetic circuits control LIN-28 abundance: it is negatively regulated by the miRNA lin-4, and positively regulated by the transcription factor LIN-14 through a mechanism that was previously unknown. In this report, we used animals that lack lin-4 to elucidate LIN-14’s activity in this circuit. We demonstrate that three let-7 family miRNAs—miR-48, miR-84, and miR-241—inhibit lin-28 expression. Furthermore, we show genetically that these miRNAs act between lin-14 and lin-28, and that they comprise the pathway by which lin-14 positively regulates lin-28. We also show that the lin-4 family member mir-237, also regulates early cell fates. Finally, we show that the expression of these miRNAs is directly inhibited by lin-14 activity, making them the first known targets of lin-14 that act in the heterochronic pathway
High-order Radio Frequency Differentiation via Photonic Signal Processing with an Integrated Micro-resonator Kerr Optical Frequency Comb Source
We demonstrate the use of integrated micro-resonator based optical frequency
comb sources as the basis for transversal filtering functions for microwave and
radio frequency photonic filtering and advanced functions.Comment: 8 pages, 7 figures, 46 References. arXiv admin note: substantial text
overlap with arXiv:1512.01741, arXiv:1512.0630
Harnessing optical micro-combs for microwave photonics
In the past decade, optical frequency combs generated by high-Q
micro-resonators, or micro-combs, which feature compact device footprints, high
energy efficiency, and high-repetition-rates in broad optical bandwidths, have
led to a revolution in a wide range of fields including metrology, mode-locked
lasers, telecommunications, RF photonics, spectroscopy, sensing, and quantum
optics. Among these, an application that has attracted great interest is the
use of micro-combs for RF photonics, where they offer enhanced functionalities
as well as reduced size and power consumption over other approaches. This
article reviews the recent advances in this emerging field. We provide an
overview of the main achievements that have been obtained to date, and
highlight the strong potential of micro-combs for RF photonics applications. We
also discuss some of the open challenges and limitations that need to be met
for practical applications.Comment: 32 Pages, 13 Figures, 172 Reference
Emerging applications of integrated optical microcombs for analogue RF and microwave photonic signal processing
We review new applications of integrated microcombs in RF and microwave
photonic systems. We demonstrate a wide range of powerful functions including a
photonic intensity high order and fractional differentiators, optical true time
delays, advanced filters, RF channelizer and other functions, based on a Kerr
optical comb generated by a compact integrated microring resonator, or
microcomb. The microcomb is CMOS compatible and contains a large number of comb
lines, which can serve as a high performance multiwavelength source for the
transversal filter, thus greatly reduce the cost, size, and complexity of the
system. The operation principle of these functions is theoretically analyzed,
and experimental demonstrations are presented.Comment: 16 pages, 8 figures, 136 References. Photonics West 2018 invited
paper, expanded version. arXiv admin note: substantial text overlap with
arXiv:1710.00678, arXiv:1710.0861
High performance photonic microwave filters based on a 50GHz optical soliton crystal Kerr micro-comb
We demonstrate a photonic radio frequency (RF) transversal filter based on an
integrated optical micro-comb source featuring a record low free spectral range
of 49 GHz yielding 80 micro-comb lines across the C-band. This record-high
number of taps, or wavelengths for the transversal filter results in
significantly increased performance including a QRF factor more than four times
higher than previous results. Further, by employing both positive and negative
taps, an improved out-of-band rejection of up to 48.9 dB is demonstrated using
Gaussian apodization, together with a tunable centre frequency covering the RF
spectra range, with a widely tunable 3-dB bandwidth and versatile dynamically
adjustable filter shapes. Our experimental results match well with theory,
showing that our transversal filter is a competitive solution to implement
advanced adaptive RF filters with broad operational bandwidths, high frequency
selectivity, high reconfigurability, and potentially reduced cost and
footprint. This approach is promising for applications in modern radar and
communications systems.Comment: 19 pages, 12 figures, 107 reference
Photonic RF and microwave reconfigurable filters and true time delays based on an integrated optical Kerr frequency comb source
We demonstrate advanced transversal radio frequency (RF) and microwave
functions based on a Kerr optical comb source generated by an integrated
micro-ring resonator. We achieve extremely high performance for an optical true
time delay aimed at tunable phased array antenna applications, as well as
reconfigurable microwave photonic filters. Our results agree well with theory.
We show that our true time delay would yield a phased array antenna with
features that include high angular resolution and a wide range of beam steering
angles, while the microwave photonic filters feature high Q factors, wideband
tunability, and highly reconfigurable filtering shapes. These results show that
our approach is a competitive solution to implementing reconfigurable, high
performance and potentially low cost RF and microwaveComment: 15 pages, 11 Figures, 60 Reference
Применение полимерного геля для оценки коррозионной устойчивости титановых сплавов
We propose and experimentally demonstrate a microwave photonic intensity differentiator based on a Kerr optical comb generated by a compact integrated micro-ring resonator (MRR). The on-chip Kerr optical comb, containing a large number of comb lines, serves as a high-performance multi-wavelength source for implementing a transversal filter, which will greatly reduce the cost, size, and complexity of the system. Moreover, owing to the compactness of the integrated MRR, frequency spacings of up to 200-GHz can be achieved, enabling a potential operation bandwidth of over 100 GHz. By programming and shaping individual comb lines according to calculated tap weights, a reconfigurable intensity differentiator with variable differentiation orders can be realized. The operation principle is theoretically analyzed, and experimental demonstrations of the first-, second-, and third-order differentiation functions based on this principle are presented. The radio frequency amplitude and phase responses of multi-order intensity differentiations are characterized, and system demonstrations of real-time differentiations for a Gaussian input signal are also performed. The experimental results show good agreement with theory, confirming the effectiveness of our approach
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