Single Electron Elliptic Flow Measurements in Au+Au Collisions from STAR

Recent measurements of elliptic flow (v_2) and the nuclear modification factor (R_{CP}) of strange mesons and baryons in the intermediate p_T domain in Au+Au collisions demonstrate a scaling with the number of constituent-quarks. This suggests hadron production via quark coalescence from a thermalized parton system. Measuring the elliptic flow of charmed hadrons, which are believed to originate rather from fragmentation than from coalescence processes, might therefore change our view of hadron production in heavy ion collisions. While direct v_2 measurements of charmed hadrons are currently not available, single electron v_2 at sufficiently high transverse momenta can serve as a substitute. At transverse momenta above 2 GeV/c, the production of single electrons from non-photonic sources is expected to be dominated by the decay of charmed hadrons. Simulations show a strong correlation between the flow of the charmed hadrons and the flow of their decay electrons for p_T > 2 GeV/c. We will present preliminary STAR results from our single electron v_2 measurements from Au+Au collisions at RHIC energies.Comment: 10 pages, 7 figures Proceedings of the Hot Quarks 2004 Conference, July 18-24 2004, Taos Valley, New Mexico, USA to be published in Journal of Physics

Overview of charm production at RHIC

In this presentation, I discussed a) the charm total cross-section and its comparisons to measurements at other beam energies and pQCD calculations; b) the semileptonic decay of charmed hadrons and the sensitivity of non-photonic leptons to charm quark collective flow and freeze-out; c) semileptonic decayed electron spectrum at high transverse momentum, its comparison to FONLL in p+p and d+Au collisions, and heavy-quark energy loss in Au+Au collisions.Comment: 8 pages, 4 figures, overview talk at SQM2006: Strangeness in Quark Matter Los Angeles, CA, Mar. 26-31, 2006; minor text changes and references adde

Submesoscale eddy and frontal instabilities in the Kuroshio interacting with a cape south of Taiwan

Author Posting. © American Geophysical Union, 2020. 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: Oceans 125(5), (2020): e2020JC016123, doi:10.1029/2020JC016123.The processes underlying the strong Kuroshio encountering a cape at the southernmost tip of Taiwan are examined with satellite‐derived chlorophyll and temperature maps, a drifter trajectory, and realistic model simulations. The interaction spurs the formation of submesoscale cyclonic eddies that trap cold and high‐chlorophyll water and the formation of frontal waves between the free stream and the wake flow. An observed train of eddies, which have relative vorticity about one to four times the planetary vorticity (f), is shed from the recirculation that occurs in the immediate lee of the cape as a result of flow separation. These propagate downstream at a speed of 0.5–0.6 m s−1. Farther downstream, the corotation and merging of two or three adjacent eddies are common owing to the topography‐induced slowdown of eddy propagation farther downstream. It is found that the relative vorticity of a corotating system (1.2f) is 70% weaker than that of a single eddy due to the increase of eddy diameter from ~16 to ~33 km, in agreement with Kelvin's circulation theorem. The shedding period of the submesoscale eddies is strongly modulated by either diurnal or semidiurnal tidal flows, which typically reach 0.2–0.5 m s−1, whereas its intrinsic shedding period is insignificant. The frontal waves predominate in the horizontal free shear layer emitted from the cape, as well as a density front. Energetics analysis suggests that the wavy features result primarily from the growth of barotropic instability in the free shear layer, which may play a secondary process in the headland wake.Yu‐Hsin Cheng was supported by the CWB of Taiwan through Grant 1062076C. Ming‐Huei Chang was supported by the Ministry of Science and Technology of Taiwan (MOST) under Grants 103‐2611‐M‐002‐018, 105‐2611‐M‐002‐012, and 107‐2611‐M‐002‐015. Sen Jan was supported with MOST Grants 101‐2611‐M‐002‐018‐MY3, 103‐2611‐M‐002‐011, and 105‐2119‐M‐002‐042. Magdalena Andres was supported by the U.S. Office of Naval Research Grant N000141613069.2020-10-2

Ex vivo detection and characterization of early dental caries by optical coherence tomography and Raman spectroscopy.

Early dental caries detection will facilitate implementation of nonsurgical methods for arresting caries progression and promoting tooth remineralization. We present a method that combines optical coherence tomography (OCT) and Raman spectroscopy to provide morphological information and biochemical specificity for detecting and characterizing incipient carious lesions found in extracted human teeth. OCT imaging of tooth samples demonstrated increased light backscattering intensity at sites of carious lesions as compared to the sound enamel. The observed lesion depth on an OCT image was approximately 290 mm matching those previously documented for incipient caries. Using Raman microspectroscopy and fiber-optic- based Raman spectroscopy to characterize the caries further, spectral changes were observed in PO 42 vibrations arising from hydroxyapa- tite of mineralized tooth tissue. Examination of various ratios of PO 42 n 2 , n 3 , n 4 vibrations against the n 1 vibration showed consistent in- creases in carious lesions compared to sound enamel. The changes were attributed to demineralization-induced alterations of enamel crystallite morphology and/or orientation. OCT imaging is useful for screening carious sites and determining lesion depth, with Raman spectroscopy providing biochemical confirmation of caries. The com- bination has potential for development into a new fiber-optic diagnos- tic tool enabling dentists to identify early caries lesions with greater sensitivity and specificity. © 2005 Society of Photo-Optical Instrumentation Engi

Impacts of Tides and Typhoon Fanapi (2010) on Seas Around Taiwan

We used satellite data, typhoon-resolving atmospheric forcing and a data assimilating ocean model, the East Asian Seas Nowcast/Forecast System (EASNFS), to investigate circulation and three upwelling regions perturbed by tides and Typhoon Fanapi (2010) in the seas around Taiwan. The three upwelling areas located off northeast Taiwan, off southeast China and over the Penghu Channel off southwest Taiwan are normally limited in expanse before Fanapi. The tidal currents enhance all three. To cope with typhoon strength atmospheric forcing, we applied typhoon-resolving Weather Research and Forecasting (WRF) model wind fields that significantly enhanced Fanapi-induced upwelling. Approaching Taiwan, Fanapi induces a cold wake spreading preferably on the right side of the essentially westward running track in the western Pacific. The three upwelling areas in the East China Sea and Taiwan Strait subsequently become expansive as Fanapi approaches and enters the Taiwan Strait. The mechanisms leading to normal or Fanapi-perturbed upwelling and circulation in seas around Taiwan, especially the latter two mentioned above, are suggested. In essence, Fanapi disrupts circulation in the Taiwan Strait, and also the Taiwan Strait outflow entering the East China Sea, leading to expanded upwelling areas. We also suggest that high-resolution wind and tides application is essential for the upwelling modeling study and also the general circulation in the region with and without typhoons

Strong tuning of Rashba spin orbit interaction in single InAs nanowires

A key concept in the emerging field of spintronics is the gate voltage or electric field control of spin precession via the effective magnetic field generated by the Rashba spin orbit interaction. Here, we demonstrate the generation and tuning of electric field induced Rashba spin orbit interaction in InAs nanowires where a strong electric field is created either by a double gate or a solid electrolyte surrounding gate. In particular, the electrolyte gating enables six-fold tuning of Rashba coefficient and nearly three orders of magnitude tuning of spin relaxation time within only 1 V of gate bias. Such a dramatic tuning of spin orbit interaction in nanowires may have implications in nanowire based spintronic devices.Comment: Nano Letters, in pres

Suppression of stored-beam oscillation and observation of flux improvement during top-up injection

This paper describes a start-to-end study of the suppression of stored-beam oscillation during top-up injection at the Pohang Light Source (PLS-II) beam line. The fast counterkicker implemented in PLS-II suppresses stored-beam oscillations in the vertical plane. During top-up injection in the magnetic spectroscopy beam line of PLS-II, flux improvement due to the suppression of stored-beam oscillation was clearly observed.11Ysciescopu

Inducible Nucleosome Depletion at OREBP-Binding-Sites by Hypertonic Stress

Background: Osmotic Response Element-Binding Protein (OREBP), also known as TonEBP or NFAT5, is a unique transcription factor. It is hitherto the only known mammalian transcription factor that regulates hypertonic stress-induced gene transcription. In addition, unlike other monomeric members of the NFAT family, OREBP exists as a homodimer and it is the only transcription factor known to bind naked DNA targets by complete encirclement in vitro. Nevertheless, how OREBP interacts with target DNA, also known as ORE/TonE, and how it elicits gene transcription in vivo, remains unknown. Methodology: Using hypertonic induction of the aldose reductase (AR) gene activation as a model, we showed that OREs contained dynamic nucleosomes. Hypertonic stress induced a rapid and reversible loss of nucleosome(s) around the OREs. The loss of nucleosome(s) was found to be initiated by an OREBP-independent mechanism, but was significantly potentiated in the presence of OREBP. Furthermore, hypertonic induction of AR gene was associated with an OREBPdependent hyperacetylation of histones that spanned the 59 upstream sequences and at least some exons of the gene. Nevertheless, nucleosome loss was not regulated by the acetylation status of histone. Significance: Our findings offer novel insights into the mechanism of OREBP-dependent transcriptional regulation and provide a basis for understanding how histone eviction and transcription factor recruitment are coupled. © 2009 Tong et al.published_or_final_versio

Characteristics of gate-all-around silicon nanowire field effect transistors with asymmetric channel width and source/drain doping concentration

We performed 3D simulations to demonstrate structural effects in sub-20 nm gate-all-around silicon nanowire field effect transistors having asymmetric channel width along the channel direction. We analyzed the differences in the electrical and physical properties for various slopes of the channel width in asymmetric silicon nanowire field effect transistors (SNWFETs) and compared them to symmetrical SNWFETs with uniform channel width. In the same manner, the effects of the individual doping concentration at the source and drain also have been investigated. For various structural conditions, the current and switching characteristics are seriously affected. The differences attributed to the doping levels and geometric conditions are due to the electric field and electron density profile. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4745858]ope