Nanoscale Vibrational Analysis of Single-Walled Carbon Nanotubes

We use near-field Raman imaging and spectroscopy to study localized vibrational modes along individual, single-walled carbon nanotubes (SWNTs) with a spatial resolution of 10−20 nm. Our approach relies on the enhanced field near a laser-irradiated gold tip which acts as the Raman excitation source. We find that for arc-discharge SWNTs, both the radial breathing mode (RBM) and intermediate frequency mode (IFM) are highly localized. We attribute such localization to local changes in the tube structure (n, m). In comparison, we observe no such localization of the Raman active modes in SWNTs grown by chemical vapor deposition (CVD). The direct comparison between arc-discharge and CVD-grown tubes allows us to rule out any artifacts induced by the supporting substrate

Upper ocean momentum balances in the western equatorial Pacific on the intraseasonal time scale

Author Posting. © The Authors, 2004. This is the author's version of the work. It is posted here by permission of Elsevier B. V. for personal use, not for redistribution. The definitive version was published in Deep Sea Research Part I: Oceanographic Research Papers 52 (2005): 749-765, doi:10.1016/j.dsr.2004.12.004.Surface Meteorology, upper ocean current, and hydrographic measurements, collected along a repeated survey pattern and from a central mooring in the western equatorial Pacific during late 1992 to early 1993, were used to analyse upper ocean momentum balances on the intraseasonal time scale. Wind stresses derived from meteorological measurements were compared with numerical weather prediction products. Advection terms in the momentum equations were estimated by planar fits to the current and hydrographic data. Pressure gradient terms were derived from planar fits to the dynamic heights calculated from the hydrographic data, referenced by balancing the momentum equation in a selected layer below the mixed layer. Under prevailing westerly winds, westward pressure gradient forcings of 2x10-7 m s-2 were set up in the western equatorial Pacific, countering the surface wind, while the total advection tended to accelerate the eastward momentum in the surface layer. During both calm wind and westerly wind burst periods, zonal turbulent momentum fluxes estimated from the ocean budgets were comparable with those estimated from microstructure dissipation rate measurements and with zonal wind stresses, so that the zonal momentum could be balanced within error bars. The meridional momentum balances were noisier, which might be due to the fact that the short meridional length scale of the equatorial inertial-gravity waves could contaminate the dynamic signals in the mixed temporal/spatial sampling data, so that the meridional gradient estimates from the planar fits could be biased.MF acknowledges the support of Strategic Research Fund for Marine Environment. RL and PH were supported by NSF grant OCE-9525986. RW and AP were supported by NSF Grants OCE- 9110559 and OCE-9110554, respectively

Sea Surface Salinity And Barrier Layer Variability In The Equatorial Pacific As Seen From Aquarius And Argo

ISI Document Delivery No.: AB6DZ Times Cited: 0 Cited Reference Count: 52 Cited References: Alory G, 2012, J GEOPHYS RES-OCEANS, V117, DOI 10.1029/2011JC007802 Ando K, 1997, J GEOPHYS RES-OCEANS, V102, P23063, DOI 10.1029/97JC01443 Argo Steering Team, 1998, 21 ARG STEER TEAM IN, V21 BINGHAM FM, 1995, DEEP-SEA RES PT I, V42, P1545, DOI 10.1016/0967-0637(95)00064-D Bosc C, 2009, J GEOPHYS RES-OCEANS, V114, DOI 10.1029/2008JC005187 Boutin J, 2013, OCEAN SCI, V9, P183, DOI 10.5194/os-9-183-2013 Boyer TP, 2002, J GEOPHYS RES-OCEANS, V107, DOI 10.1029/2001JC000829 Chen D, 2004, J TROP OCEANOGR, V23, P1 Cronin MF, 2002, J GEOPHYS RES-OCEANS, V107, DOI 10.1029/2001JC001171 de Boyer Montegut C., 2004, J GEOPHYS RES, V109, DOI 10.1029/2004JC002378 Delcroix T, 2002, J GEOPHYS RES-OCEANS, V107, DOI 10.1029/2001JC000862 DELCROIX T, 1992, J GEOPHYS RES-OCEANS, V97, P5423, DOI 10.1029/92JC00127 Fujii Y, 2003, J GEOPHYS RES-OCEANS, V108, DOI 10.1029/2002JC001745 GODFREY JS, 1989, J GEOPHYS RES-OCEANS, V94, P8007, DOI 10.1029/JC094iC06p08007 Hasegawa T, 2013, J CLIMATE, V26, P8126, DOI 10.1175/JCLI-D-12-00187.1 Henocq C, 2010, J ATMOS OCEAN TECH, V27, P192, DOI 10.1175/2009JTECHO670.1 Johnson ES, 2002, J GEOPHYS RES-OCEANS, V107, DOI 10.1029/2001JC001122 Juza M, 2012, J OPER OCEANOGR, V5, P45 Kalnay E, 1996, B AM METEOROL SOC, V77, P437, DOI 10.1175/1520-0477(1996)0772.0.CO;2 Kessler WS, 1998, J CLIMATE, V11, P777, DOI 10.1175/1520-0442(1998)0112.0.CO;2 KESSLER WS, 1990, J GEOPHYS RES-OCEANS, V95, P5183, DOI 10.1029/JC095iC04p05183 Lagerloef G., 2013, AQ014OPS0016 Lagerloef G, 2008, OCEANOGRAPHY, V21, P68 Lee T, 2012, GEOPHYS RES LETT, V39, DOI 10.1029/2012GL052232 Levitus S., 1982, 13 NOAA LINDSTROM E, 1987, NATURE, V330, P533, DOI 10.1038/330533a0 LUKAS R, 1991, J GEOPHYS RES-OCEANS, V96, P3343 Maes C, 2004, GEOPHYS RES LETT, V31, DOI 10.1029/2004GL019867 Maes C, 2008, J GEOPHYS RES-OCEANS, V113, DOI 10.1029/2007JC004297 Maes C, 2011, SOLA, V7, P97, DOI 10.2151/sola.2011-025 Maes C, 2006, GEOPHYS RES LETT, V33, DOI 10.1029/2005GL024772 Maes C, 2000, GEOPHYS RES LETT, V27, P1659, DOI 10.1029/1999GL011261 Maes C, 2002, GEOPHYS RES LETT, V29, DOI 10.1029/2002GL016029 Maes C, 2005, J CLIMATE, V18, P104, DOI 10.1175/JCLI-3214.1 Lukas R, 1996, J GEOPHYS RES-OCEANS, V101, P12209, DOI 10.1029/96JC01204 MCPHADEN MJ, 1992, J GEOPHYS RES-OCEANS, V97, P14289, DOI 10.1029/92JC01197 MCPHADEN MJ, 1990, SCIENCE, V250, P1385, DOI 10.1126/science.250.4986.1385 PALMER TN, 1984, NATURE, V310, P483, DOI 10.1038/310483a0 Picaut J, 2001, J GEOPHYS RES-OCEANS, V106, P2363, DOI 10.1029/2000JC900141 Picaut J, 1997, SCIENCE, V277, P663, DOI 10.1126/science.277.5326.663 Qu TD, 1999, J PHYS OCEANOGR, V29, P1488, DOI 10.1175/1520-0485(1999)0292.0.CO;2 Qu TD, 2013, J PHYS OCEANOGR, V43, P1551, DOI 10.1175/JPO-D-12-0180.1 Qu TD, 2008, GEOPHYS RES LETT, V35, DOI 10.1029/2008GL035058 Reverdin G., 2013, OCEANOGRAPHY, V26, P4857, DOI 10.5670/oceanog.2013.04 Riser SC, 2008, OCEANOGRAPHY, V21, P56 Rodier M., 2000, J OCEANOGR, V56, P463, DOI 10.1023/A:1011136608053 SHINODA T, 1995, J GEOPHYS RES-OCEANS, V100, P2523, DOI 10.1029/94JC02486 Singh A, 2011, J GEOPHYS RES-OCEANS, V116, DOI 10.1029/2010JC006862 Song Y. T., 2013, J GEOPHYS R IN PRESS SPRINTALL J, 1992, J GEOPHYS RES-OCEANS, V97, P7305, DOI 10.1029/92JC00407 Takahashi K, 2011, GEOPHYS RES LETT, V38, DOI 10.1029/2011GL047364 Yu JY, 2007, J GEOPHYS RES-ATMOS, V112, DOI 10.1029/2006JD007654 Qu, Tangdong Song, Y. Tony Maes, Christophe NSF [OCE11-30050]; NASA [NNX12AG02G]; Jet Propulsion Laboratory, California Institute of Technology, under NASA; IRD T. Qu was supported by NSF through grant OCE11-30050 and by NASA as part of the Aquarius Science Team investigation through grant NNX12AG02G. Y. T. Song was supported by the Jet Propulsion Laboratory, California Institute of Technology, under contracts with NASA. C. Maes is supported by IRD. The authors are grateful to N. Schneider and I. Fukumori for useful discussion on the topic, to K. Yu for assistance in processing the Aquarius data, and to two anonymous reviewers for valuable comments on this manuscript. School of Ocean and Earth Science and Technology contribution number 9054 and International Pacific Research Center contribution IPRC-1033. 0 AMER GEOPHYSICAL UNION WASHINGTON J GEOPHYS RES-OCEANSThis study investigates the sea surface salinity (SSS) and barrier layer variability in the equatorial Pacific using recently available Aquarius and Argo data. Comparison between the two data sets indicates that Aquarius is able to capture most of the SSS features identified by Argo. Despite some discrepancies in the mean value, the SSS from the two data sets shows essentially the same seasonal cycle in both magnitude and phase. For the period of observation between August 2011 and July 2013 Aquarius nicely resolved the zonal displacement of the SSS front along the equator, showing its observing capacity of the western Pacific warm pool. Analysis of the Argo data provides further information on surface stratification. A thick barrier layer is present on the western side of the SSS front during all the period of observation, moving back and forth along the equator with its correlation with the Southern Oscillation Index exceeding 0.80. Generally, the thick barrier layer moves eastward during El Nino and westward during La Nina. The mechanisms responsible for this zonal displacement are discussed. Key Points Aquarius nicely resolved the SSS front along the equator in the western Pacific A thick barrier layer is always present on the western side of the SSS front Both the SSS front and thick barrier layer are highly correlated with ENS

A global relationship between the ocean water cycle and near-surface salinity

Author Posting. © American Geophysical Union, 2011. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 116 (2011): C10025, doi:10.1029/2010JC006937.Ocean evaporation (E) and precipitation (P) are the fundamental components of the global water cycle. They are also the freshwater flux forcing (i.e., E-P) for the open ocean salinity. The apparent connection between ocean salinity and the global water cycle leads to the proposition of using the oceans as a rain gauge. However, the exact relationship between E-P and salinity is governed by complex upper ocean dynamics, which may complicate the inference of the water cycle from salinity observations. To gain a better understanding of the ocean rain gauge concept, here we address a fundamental issue as to how E-P and salinity are related on the seasonal timescales. A global map that outlines the dominant process for the mixed-layer salinity (MLS) in different regions is thus derived, using a lower-order MLS dynamics that allows key balance terms (i.e., E-P, the Ekman and geostrophic advection, vertical entrainment, and horizontal diffusion) to be computed from satellite-derived data sets and a salinity climatology. Major E-P control on seasonal MLS variability is found in two regions: the tropical convergence zones featuring heavy rainfall and the western North Pacific and Atlantic under the influence of high evaporation. Within this regime, E-P accounts for 40–70% MLS variance with peak correlations occurring at 2–4 month lead time. Outside of the tropics, the MLS variations are governed predominantly by the Ekman advection, and then vertical entrainment. The study suggests that the E-P regime could serve as a window of opportunity for testing the ocean rain gauge concept once satellite salinity observations are available.The study was supported by the NASA Remote Sensing Science for Carbon and Climate program under grant NNX07AF97G and by the NSF Physical Oceanography program under grant OCE‐0647949

On sea surface salinity skin effect iInduced by evaporation and implications for remote sensing of ocean salinity

Author Posting. © American Meteorological Society, 2010. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 46 (2010): 85-102, doi:10.1175/2009JPO4168.1.The existence of a cool and salty sea surface skin under evaporation was first proposed by Saunders in 1967, but few efforts have since been made to perceive the salt component of the skin layer. With two salinity missions scheduled to launch in the coming years, this study attempted to revisit the Saunders concept and to utilize presently available air–sea forcing datasets to analyze, understand, and interpret the effect of the salty skin and its implication for remote sensing of ocean salinity. Similar to surface cooling, the skin salinification would occur primarily at low and midlatitudes in regions that are characterized by low winds or high evaporation. On average, the skin is saltier than the interior water by 0.05–0.15 psu and cooler by 0.2°–0.5°C. The cooler and saltier skin at the top is always statically unstable, and the tendency to overturn is controlled by cooling. Once the skin layer overturns, the time to reestablish the full increase of skin salinity was reported to be on the order of 15 min, which is approximately 90 times slower than that for skin temperature. Because the radiation received from a footprint is averaged over an area to give a single pixel value, the slow recovery by the salt diffusion process might cause a slight reduction in area-averaged skin salinity and thus obscure the salty skin effect on radiometer retrievals. In the presence of many geophysical error sources in remote sensing of ocean salinity, the salt enrichment at the surface skin does not appear to be a concern

ACE2 is the critical in vivo receptor for SARS-CoV-2 in a novel COVID-19 mouse model with TNF-and IFN?-driven immunopathology

Despite tremendous progress in the understanding of COVID-19, mechanistic insight into immunological, disease-driving factors remains limited. We generated maVie16, a mouse-adapted SARS-CoV-2, by serial passaging of a human isolate. In silico modeling revealed how only three Spike mutations of maVie16 enhanced interaction with murine ACE2. maVie16 induced profound pathology in BALB/c and C57BL/6 mice, and the resulting mouse COVID-19 (mCOVID-19) replicated critical aspects of human disease, including early lymphopenia, pulmonary immune cell infiltration, pneumonia, and specific adaptive immunity. Inhibition of the proinflammatory cyto-kines IFN? and TNF substantially reduced immunopathology. Importantly, genetic ACE2-deficiency completely prevented mCOVID-19 development. Finally, inhalation therapy with recombinant ACE2 fully protected mice from mCOVID-19, revealing a novel and efficient treatment. Thus, we here present maVie16 as a new tool to model COVID-19 for the discovery of new therapies and show that disease severity is determined by cytokine-driven immunopathology and critically dependent on ACE2 in vivo. © Gawish et al

Origin and Propagation of Extremely High Energy Cosmic Rays

Cosmic ray particles with energies in excess of 10**(20) eV have been detected. The sources as well as the physical mechanism(s) responsible for endowing cosmic ray particles with such enormous energies are unknown. This report gives a review of the physics and astrophysics associated with the questions of origin and propagation of these Extremely High Energy (EHE) cosmic rays in the Universe. After a brief review of the observed cosmic rays in general and their possible sources and acceleration mechanisms, a detailed discussion is given of possible "top-down" (non-acceleration) scenarios of origin of EHE cosmic rays through decay of sufficiently massive particles originating from processes in the early Universe. The massive particles can come from collapse and/or annihilation of cosmic topological defects (such as monopoles, cosmic strings, etc.) associated with Grand Unified Theories or they could be some long-lived metastable supermassive relic particles that were created in the early Universe and are decaying in the current epoch. The highest energy end of the cosmic ray spectrum can thus be used as a probe of new fundamental physics beyond Standard Model. We discuss the role of existing and proposed cosmic ray, gamma-ray and neutrino experiments in this context. We also discuss how observations with next generation experiments of images and spectra of EHE cosmic ray sources can be used to obtain new information on Galactic and extragalactic magnetic fields and possibly their origin.Comment: 148 latex pages in tight format, 30 postscript-files and two gif-files for fig4.14 and fig4.15 included, uses epsf.sty. Considerably updated version of review to appear in Physics Reports. Links and color ps version of fig4.14 and fig4.15 at http://astro.uchicago.edu/home/web/sigl/physrep.htm

Measurement of the cosmic ray spectrum above 4×10184{\times}10^{18} eV using inclined events detected with the Pierre Auger Observatory

A measurement of the cosmic-ray spectrum for energies exceeding $4{\times}10^{18}$ eV is presented, which is based on the analysis of showers with zenith angles greater than $60^{\circ}$ detected with the Pierre Auger Observatory between 1 January 2004 and 31 December 2013. The measured spectrum confirms a flux suppression at the highest energies. Above $5.3{\times}10^{18}$ eV, the "ankle", the flux can be described by a power law $E^{-\gamma}$ with index $\gamma=2.70 \pm 0.02 \,\text{(stat)} \pm 0.1\,\text{(sys)}$ followed by a smooth suppression region. For the energy ($E_\text{s}$) at which the spectral flux has fallen to one-half of its extrapolated value in the absence of suppression, we find $E_\text{s}=(5.12\pm0.25\,\text{(stat)}^{+1.0}_{-1.2}\,\text{(sys)}){\times}10^{19}$ eV.Comment: Replaced with published version. Added journal reference and DO

Energy Estimation of Cosmic Rays with the Engineering Radio Array of the Pierre Auger Observatory

The Auger Engineering Radio Array (AERA) is part of the Pierre Auger Observatory and is used to detect the radio emission of cosmic-ray air showers. These observations are compared to the data of the surface detector stations of the Observatory, which provide well-calibrated information on the cosmic-ray energies and arrival directions. The response of the radio stations in the 30 to 80 MHz regime has been thoroughly calibrated to enable the reconstruction of the incoming electric field. For the latter, the energy deposit per area is determined from the radio pulses at each observer position and is interpolated using a two-dimensional function that takes into account signal asymmetries due to interference between the geomagnetic and charge-excess emission components. The spatial integral over the signal distribution gives a direct measurement of the energy transferred from the primary cosmic ray into radio emission in the AERA frequency range. We measure 15.8 MeV of radiation energy for a 1 EeV air shower arriving perpendicularly to the geomagnetic field. This radiation energy -- corrected for geometrical effects -- is used as a cosmic-ray energy estimator. Performing an absolute energy calibration against the surface-detector information, we observe that this radio-energy estimator scales quadratically with the cosmic-ray energy as expected for coherent emission. We find an energy resolution of the radio reconstruction of 22% for the data set and 17% for a high-quality subset containing only events with at least five radio stations with signal.Comment: Replaced with published version. Added journal reference and DO