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Institution

University of Hawaii at Manoa

EducationHonolulu, Hawaii, United States
About: University of Hawaii at Manoa is a education organization based out in Honolulu, Hawaii, United States. It is known for research contribution in the topics: Population & Sea surface temperature. The organization has 13693 authors who have published 25161 publications receiving 1023924 citations.


Papers
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Journal ArticleDOI
13 Mar 2008-Nature
TL;DR: The Gulf Stream is the upper limb of the Atlantic meridional overturning circulation, which has varied in strength in the past and is predicted to weaken in response to human-induced global warming in the future.
Abstract: The Gulf Stream is a warm Atlantic current that transports heat northward, keeping Western Europe significantly warmer than North America in winter. It is known to influence short-term weather phenomena such as surface winds and cyclone formation, but its effects on longer-term climate and at higher levels in the atmosphere are poorly understood. Now a combination of weather analyses, satellite data and an atmospheric general circulation model reveals that the Gulf Stream's influence is felt well above the near-surface portion of the atmosphere. The current anchors a tall wall of atmospheric upward motion that penetrates into the upper troposphere and supports deep raining clouds. This provides a pathway by which the Gulf Stream can affect local climate, and possibly climate in remote regions via an effect on planetary wave propagation. The cover graphic represents surface current speeds in blue-white colours (white is the fastest) and upward wind velocities in yellow-red colours (red for stronger winds), along with land-surface topography in eastern North America. The Gulf Stream's influence on the atmosphere is examined using a combination of operational weather analyses and satellite observations. The results indicate that the Gulf Stream anchors a rain band in which upward motion of air penetrates deep into the upper troposphere, well above the near-surface portion of the atmosphere. These mechanisms provide a pathway by which the Gulf Stream can affect local climate, and possibly also climate in remote regions. The Gulf Stream transports large amounts of heat from the tropics to middle and high latitudes, and thereby affects weather phenomena such as cyclogenesis1,2 and low cloud formation3. But its climatic influence, on monthly and longer timescales, remains poorly understood. In particular, it is unclear how the warm current affects the free atmosphere above the marine atmospheric boundary layer. Here we consider the Gulf Stream’s influence on the troposphere, using a combination of operational weather analyses, satellite observations and an atmospheric general circulation model4. Our results reveal that the Gulf Stream affects the entire troposphere. In the marine boundary layer, atmospheric pressure adjustments to sharp sea surface temperature gradients lead to surface wind convergence, which anchors a narrow band of precipitation along the Gulf Stream. In this rain band, upward motion and cloud formation extend into the upper troposphere, as corroborated by the frequent occurrence of very low cloud-top temperatures. These mechanisms provide a pathway by which the Gulf Stream can affect the atmosphere locally, and possibly also in remote regions by forcing planetary waves5,6. The identification of this pathway may have implications for our understanding of the processes involved in climate change, because the Gulf Stream is the upper limb of the Atlantic meridional overturning circulation, which has varied in strength in the past7 and is predicted to weaken in response to human-induced global warming in the future8.

639 citations

Journal ArticleDOI
TL;DR: In this paper, the phase relationship between the received signal and the local oscillator has a significant effect on the demodulation sensitivity, and the null points can be avoided with a quadrature (I/Q) receiver.
Abstract: Direct-conversion microwave Doppler-radar transceivers have been fully integrated in 0.25-/spl mu/m silicon CMOS and BiCMOS technologies. These chips, operating at 1.6 and 2.4 GHz, have detected movement due to heartbeat and respiration 50 cm from the subject, which may be useful in infant and adult apnea monitoring. The range-correlation effect on residual phase noise is a critical factor when detecting small phase fluctuations with a high-phase-noise on-chip oscillator. Phase-noise reduction due to range correlation was experimentally evaluated, and the measured residual phase noise was within 5 dB of predicted values on average. In a direct-conversion receiver, the phase relationship between the received signal and the local oscillator has a significant effect on the demodulation sensitivity, and the null points can be avoided with a quadrature (I/Q) receiver. In this paper, measurements that highlight the performance benefits of an I/Q receiver are presented. While the accuracy of the heart rate measured with the single-channel chip ranges from 40% to 100%, depending on positioning, the quadrature chip accuracy is always better than 80%.

636 citations

Journal ArticleDOI
TL;DR: It is reported here that a single neurotoxin, beta-N-methylamino-L-alanine, may be produced by all known groups of cyanobacteria, including cyanobacterial symbionts and free-living cyanob bacteria.
Abstract: Cyanobacteria can generate molecules hazardous to human health, but production of the known cyanotoxins is taxonomically sporadic. For example, members of a few genera produce hepatotoxic microcystins, whereas production of hepatotoxic nodularins appears to be limited to a single genus. Production of known neurotoxins has also been considered phylogenetically unpredictable. We report here that a single neurotoxin, β-N-methylamino-l-alanine, may be produced by all known groups of cyanobacteria, including cyanobacterial symbionts and free-living cyanobacteria. The ubiquity of cyanobacteria in terrestrial, as well as freshwater, brackish, and marine environments, suggests a potential for wide-spread human exposure.

633 citations

Journal ArticleDOI
TL;DR: This paper reviews recent advances in biomedical and healthcare applications of Doppler radar that remotely detects heartbeat and respiration of a human subject and reviews different architectures, baseband signal processing, and system implementations.
Abstract: This paper reviews recent advances in biomedical and healthcare applications of Doppler radar that remotely detects heartbeat and respiration of a human subject. In the last decade, new front-end architectures, baseband signal processing methods, and system-level integrations have been proposed by many researchers in this field to improve the detection accuracy and robustness. The advantages of noncontact detection have drawn interests in various applications, such as energy smart home, baby monitor, cardiopulmonary activity assessment, and tumor tracking. While many of the reported systems were bench-top prototypes for concept verification, several portable systems and integrated radar chips have been demonstrated. This paper reviews different architectures, baseband signal processing, and system implementations. Validations of this technology in a clinical environment will also be discussed.

625 citations


Authors

Showing all 13867 results

NameH-indexPapersCitations
Pulickel M. Ajayan1761223136241
Steven N. Blair165879132929
Qiang Zhang1611137100950
Jack M. Guralnik14845383701
Thomas J. Smith1401775113919
James A. Richardson13636375778
Donna Neuberg13581072653
Jian Zhou128300791402
Eric F. Bell12863172542
Jorge Luis Rodriguez12883473567
Bin Wang126222674364
Nicholas J. Schork12558762131
Matthew Jones125116196909
Anthony F. Jorm12479867120
Adam G. Riess118363117310
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
202362
2022244
20211,111
20201,164
20191,151
20181,154