Narrow Spread Research Articles

Electric field reversals resulting from voltage waveform tailoring in Ar/O2 capacitively coupled plasmas sustained in asymmetric systems

The etching of nanometer scale high-aspect-ratio (HAR) features into dielectric materials in low pressure radio frequency excited plasmas is often accompanied by charge accumulation inside the features which can slow etching rates and produce distortions such as twisting. The intra-feature charging is at least partially produced by differences in electron and ion energy and angular distributions (EADs). Positive ions, accelerated to high energies having narrow angular spreads by the sheath electric field, can penetrate deeply into HAR features. Electrons typically arrive at the wafer with nearly thermal and isotropic distributions and do not penetrate deeply into HAR features. These disparities lead to differential charging of the inside of the feature, which can lead to reductions in etch rate and feature distortion due to ion deflection. With increasing aspect ratio of features, charging challenges are expected to continue for the foreseeable future. In this work, the use of tailored voltage waveforms in geometrically asymmetric capacitively coupled plasmas sustained in Ar/O2 at 40 mTorr was computationally investigated with the goal of shaping the EAD of electrons incident onto the substrate to address differential charging. The tailored waveform consisted of a sinusoidal wave and its higher harmonics with a fundamental frequency of 1 MHz. We found that electric field reversals (EFRs) in the sheath and presheath can occur during the anodic portion of the cycle. The EFR increases the energy and decreases the angular spread of electrons incident onto the substrate. The magnitude of the EFR can be controlled by the phase angle of the even harmonics and the gas composition. Due to its electronegative nature, increasing mole fractions of O2 impedes electron transport to the surface which further increases the EFR.

Diffuse spreading, a newly recognized mode of crustal accretion in the southern Mariana Trough backarc basin

Abstract South of the latitude of Guam, the Mariana Trough exhibits both trench-parallel and trench-normal extension. In this study, we examined the locus of trench-normal extension separating the Philippine Sea plate from the broadly deforming Mariana platelet. Along this boundary, we identified three distinct modes of extension and described their distinguishing characteristics using deep- and shallow-towed side-scan sonar and ship multibeam data along with regional geophysical, geochemical, and seismicity data. In the west, the Southwest Mariana Rift is an active tectonic rift exhibiting abundant strong earthquakes up to mb 6.7 and limited evidence of volcanism. In the east, the Malaguana-Gadao Ridge is a seafloor spreading center producing few and weak earthquakes less than mb 5. Between these zones, there is an ~20–40-km-wide and ~120-km-long area of high acoustic backscatter characterized by closely spaced volcano-tectonic ridges and small volcanic cones with distributed intermediate-strength seismicity up to mb 5.7. Fresh-looking volcanic rocks with high water contents and strong arc chemical affinities have been recovered from the high-backscatter zone. We interpret this morphologically and geophysically distinct zone as undergoing diffuse spreading, a distributed form of magmatic crustal accretion where new crust forms within a broad zone tens of kilometers across rather than along a narrow spreading axis. Diffuse spreading appears to be a rheological threshold effect enabled by slow opening rates and a high slab-fluid flux that facilitate the formation of a broad zone of weak hydrous lithosphere, within which new crust is accreted. Our findings describe a poorly understood process in plate tectonics, and observations of similar terrains in other backarc basins suggest that this process is not unique to the Mariana Trough.

Fully automated CMR derived stroke volume correlates with right heart catheter measurements in patients with suspected pulmonary hypertension

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): Welcome Trust (UK), NIHR (UK) Introduction Cardiac magnetic resonance (CMR) assessment plays a significant role in the diagnosis, prognosis and monitoring of patients with pulmonary hypertension (PH). We developed a deep learning model to automatically generate biventricular contours and validated its result in a prospective cohort of patients with suspected PH who underwent right heart catheterization (RHC). Methods A deep learning CMR contouring model was developed in a retrospective multi-vendor (Siemens and General Electric), multi-pathology cohort of patients, predominantly with heart failure, lung disease and PH (n = 400, ASPIRE registry). Biventricular segmentations were made on all CMR studies across cardiac phases. A prospective validation cohort of 102 suspected PH patients was recruited and they had RHC within 24 hours of the CMR. To test the accuracy of the automatic segmentation, the RHC-thermodilution and CMR-derived measures of stroke volume (SV) were compared for manual and automated measurements. Results The mean and standard deviation for the derived SV was 59 ml ± 21 measured by RHC and 75 ml ± 25 for automated and 79 ml ± 26 for manual CMR measurements. Automatic and manual CMR measurement correlated strongly with RHC derived SV; 0.73, 95% CI [0.62, 0.81] and 0.78, 95% CI [0.69, 0.85], respectively (figure 1). The agreement between automatic and manual SV was high; interclass correlation coefficient (ICC) = 0.88, 95% CI [0.83, 0.92] and Bland-Altman plots showed a narrow spread of mean differences between manual and automatic measurements (figure 2). Conclusion In a prospective cohort, fully automatic CMR assessments corresponded accurately to invasive hemodynamics performed within 24 hours of a CMR study.

Beaming Elastic and SERS Emission from Bent-Plasmonic Nanowire on a Mirror Cavity.

We report on the experimental observation of beaming elastic and surface enhanced Raman scattering (SERS) emission from a bent-nanowire on a mirror (B-NWoM) cavity. The system was probed with polarization resolved Fourier plane and energy-momentum imaging to study the spectral and angular signature of the emission wavevectors. The out-coupled elastically scattered light from the kink occupies a narrow angular spread. We used a self-assembled monolayer of molecules with a well-defined molecular orientation to utilize the out-of-plane electric field in the cavity for enhancing Raman emission from the molecules and in achieving beaming SERS emission. Calculated directionality for elastic scattering and SERS emission was found to be 16.2 and 12.5 dB, respectively. The experimental data were corroborated with three-dimensional numerical finite element and finite difference time domain based numerical simulations. The results presented here may find relevance in understanding coupling of emitters with elongated plasmonic cavities and in designing on-chip optical antennas.

The Grasses (Poaceae) Flora of Çapakçur Valley (Bingöl)

Bingöl, bitki çeşitliliği konusunda çalışmaların oldukça yetersiz olduğu bir ildir. Bu araştırmada, Bingöl Çapakçur Vadisi Buğdaygil (Poaceae) familyası florası verilmiştir. Tespit edilen taksonların yayılışları ile Türkiye ve komşu ülke floralarında verilen betimlemelere göre 26 taksonda varyasyon belirlenmiştir. Bu taksonlardan özellikle Alopecurus arundinaceus türünde stolon yapısının bulunması, hem Türkiye hem komşu ülke floralarında verilen betimlemelerden farklılık göstermektedir. Yapılan çalışmalar ve teşhisler sonucunda, araştırma sahasından 59 cinse ait toplam 151 takson (104 tür, 39 alttür ve 8 varyete) tespit edilmiştir. 2015 yılında Bingöl’den toplanıp; bilim dünyasına kazandırılmış olan Pseudophleum anatolicum ve 2019 yılında tanımlanan Pilgerochloa major türleri sadece Bingöl’den bilinen dar yayılışlı endemikler olup; araştırma alanında da yetiştiği belirlenmiştir. Çalışmada belirlenen taksonların 10 adedi endemik (%6.62) ve 26 adedi B8 karesi için yeni kayıttır. Çapakçur Vadisi Poaceae florasını oluşturan taksonların 29 adedi (%19.21) İran-Turan, 20 adedi (%13.24) Avrupa-Sibirya ve 9 adedi (%5.96) Akdeniz fitocoğrafik bölge elementidir. Geriye kalan taksonlar ya çok bölgeli veya fitocoğrafik bölgesi bilinmeyenlerdir.

Is there any information content of traded stocks in an emerging market? Evidence from Vietnam

The presence of foreign ownership is very limited in stocks traded in Vietnam due to the existing regulations. Significant premiums have been observed in stock trading, reflecting a result of direct negotiations between foreign institutional investors and current owners of the stocks. However, the information content of traded stocks in Vietnam has largely been ignored in the current literature. We examine the information content of listed stocks in different trade sizes of the large-capitalization stocks included in the VN30 Index. This paper uses the intraday data for constituents of the national market index, the VN30 Index, from 1st January 2017 to 14th November 2019. Our findings confirm that the ultimate impact of trade innovation size on a quote is positive, increasing and concave. The quote revision in Vietnam's stock market causing trades is found in this paper. In addition, stock trades at times of the wide spread have a more significant price impact than the narrow spread. Interestingly, findings from this paper indicate that market participants are highly unlikely to infer an information event following a large trade occurring in the market.

The ultraviolet luminosity function of star-forming galaxies between redshifts of 0.6 and 1.2

ABSTRACT We use ultraviolet (UV) imaging taken with the XMM–Newton Optical Monitor telescope (XMM-OM), covering 280 arcmin2 in the UVW1 band (λeff = 2910 Å) to measure rest-frame UV 1500-Å luminosity functions of galaxies with redshifts z between 0.6 and 1.2. The XMM-OM data are supplemented by a large body of optical and infrared imaging to provide photometric redshifts. The XMM-OM data have a significantly narrower point spread function (resulting in less source confusion) and simpler K-correction than the GALEX data previously employed in this redshift range. UV-bright active galactic nuclei are excluded to ensure that the luminosity functions relate directly to the star-forming galaxy population. Binned luminosity functions and parametric Schechter-function fits are derived in two redshift intervals: 0.6 < z < 0.8 and 0.8 < z < 1.2. We find that the luminosity function evolves such that the characteristic absolute magnitude M* is brighter for 0.8 < z < 1.2 than for 0.6 < z < 0.8.

Accurate Beam Profile Characterization in THz Transmission Imaging Systems

Beam profiling in terahertz systems based on a 4f configuration is revised to show that usual practices underestimate the beam waist due to the narrow point spread function of the detection arm. A rigorous assessment of the beam propagation shows that, by changing the focal distance of one of the focusing elements (lenses or parabolic mirrors), the beam profile can be obtained more accurately. Simulations of beam propagation were performed in order to validate the technique and in order to devise a calibration method that improves the accuracy of the profiling measurement. Measurements in both 4f and new configurations were also performed to check the consistency of the simulations.

Design of low power, variation tolerant single bitline 9T SRAM cell in 16-nm technology in subthreshold region

The major design parameters of embedded cache memory (SRAM memory cell) are speed, power consumption, noise tolerance, and reliability. It is a challenging task to design an SRAM cell in the face of process, voltage, and temperature variations at low supply voltages. At scaled technology node the conventional 6T SRAM cell suffers from read and write failures as well as instability. Moreover, it is susceptible to multibit soft error rate since it does not support bit-interleaving architecture. This paper proposes a low-power robust single bitline 9T (nine transistor) SRAM (Static Random Access Memory) at a 16-nm technology node in the subthreshold region. The potency of the proposed cell is shown by comparing it with other recently published SRAM cells, namely, single-ended NTV 9T (SENTV9T), write and read enhanced 9T (WREN9T), and the conventional 6T (CONV6T) SRAM cells. The proposed cell provides 1.25×/1.96 × lower read current IREAD variability compared with WREN9T/SENTV9T. The proposed cell achieves 4.23 × higher noise tolerance capability (i.e., read static noise margin (RSNM)) during read operation compared with CONV6T due to the fact that it employs read decoupled operation. Moreover, SBL9T consumes lower standby power during hold state and dynamic power in the active state as compared with SENTV9T, WREN9T, and CONV6T. SBL9T also exhibits 10.01×/8.65×/11.47× narrower spread in standby power compared with CONV6T/WREN9T/SENTV9T. The dynamic power spread shows a similar trend with SBL9T providing 1.97×/1.02× narrower spread in dynamic power compared with WREN9T/SENTV9T. These benefits however are achieved by the SBL9T at the cost of 1.28×/0.71×/1.01× longer read delay compared with CONV6T/WREN9T/SENTV9T.

Transition from continental rifting to oceanic spreading\xa0in the northern Red Sea\xa0area

Lithosphere extension, which plays an essential role in plate tectonics, occurs both in continents (as rift systems) and oceans (spreading along mid-oceanic ridges). The northern Red Sea area is a unique natural geodynamic laboratory, where the ongoing transition from continental rifting to oceanic spreading can be observed. Here, we analyze travel time data from a merged catalogue provided by the Egyptian and Saudi Arabian seismic networks to build a three-dimensional model of seismic velocities in the crust and uppermost mantle beneath the northern Red Sea and surroundings. The derived structures clearly reveal a high-velocity anomaly coinciding with the Red Sea basin and a narrow low-velocity anomaly centered along the rift axis. We interpret these structures as a transition of lithospheric extension from continental rifting to oceanic spreading. The transitional lithosphere is manifested by a dominantly positive seismic anomaly indicating the presence of a 50–70-km-thick and 200–300-km-wide cold lithosphere. Along the forming oceanic ridge axis, an elongated low-velocity anomaly marks a narrow localized nascent spreading zone that disrupts the transitional lithosphere. Along the eastern margins of the Red Sea, several low-velocity anomalies may represent crustal zone of massive Cenozoic basaltic magmatism.

A supersonic laser ablation beam source with narrow velocity spreads.

A supersonic beam source for SrF and BaF molecules is constructed by combining the expansion of carrier gas (a mixture of 2% SF6 and 98% argon) from an Even-Lavie valve with laser ablation of a barium/strontium metal target at a repetition rate of 10 Hz. Molecular beams with a narrow translational velocity spread are produced at relative values of Δv/v = 0.053(11) and 0.054(9) for SrF and BaF, respectively. The relative velocity spread of the beams produced in our source is lower in comparison with the results from other metal fluoride beams produced in supersonic laser ablation sources. The rotational temperature of BaF is measured to be 3.5 K. The source produces 6 × 108 and 107 molecules per steradian per pulse in the X2Σ+ (ν = 0, N = 1) state of BaF and SrF molecules, respectively, a state amenable to Stark deceleration and laser cooling.

Single‐ended half‐select disturb‐free 11T static random access memory cell for reliable and low power applications

SummaryThis paper presents an 11 transistor (SEHF11T) static random access memory (SRAM) cell with high read static noise margin (RSNM) and write static noise margin (WSNM). It eliminates the write half‐select disturb using cross‐point data‐aware write word lines, which can mitigate bit‐interleaving structure to reduce multiple‐bit upset and increase soft‐error immunity. We evaluated and analyzed the effect of process, voltage, and temperature (PVT) variations on various design metrics and compared it with other cells. The SEHF11T performs fast read operation due to its higher read current and slow write operation due to its single‐ended nature. It employs the read decoupling technique to enhance the RSNM. The stacked transistors in the left/right half‐cell increase the RSNM. In addition, the WSNM is improved by eliminating the feedback of cross‐coupled inverters pair during write operation by means of power‐cutoff write‐assist technique. The proposed cell shows 1.11X higher RSNM and 1.37X higher WSNM compared to fully differential 8T (FD8T) cell. The stacked transistors in the cell reduce leakage power dissipation. The SEHF11T consumes 0.47X lower leakage power compared to FD8T at VDD = 0.7 V. Furthermore, it exhibits high reliability against PVT variations in subthreshold region and shows 1.09X narrower spread in leakage power than that of FD8T at VDD = 0.3 V.

Design of an enhanced write stability, high-performance, low power 11T SRAM cell

ABSTRACT In the present era of diminishing technology nodes, stability and performance of SRAM cells deteriorate. To cope up with the above growing concerns, a new 11 T SRAM cell has been proposed which improves the stability in all operating modes of SRAM as well as the delay and power in the write mode. At worst process corner SS, the write 0 delay has been improved by 14.01%, 6.75%, 115.72% and 26.61% compared to 6 T, 8 TG, 10 TDiff and 11 T SRAM designs and write 1 delay has been improved by 9.2%, 88.639%, 13.69% and 71.42% compared to 6 T, 10 TDiff, DDS11T and 11 T designs at 0.9 V supply voltage. The impact of PVT variations has been studied on SNM, Write Margin, Read & Write delay, Leakage Power. The Monte Carlo simulation has been performed to study the effect of variability. P11T SRAM cell exhibits narrower spread in the distribution of majority design metrics. The removal of the half-select issue has been illustrated in the P11T SRAM cell using Monte Carlo simulations. Post-Layout simulation has been carried out to evaluate different design metrics at 45 nm technology node in Cadence Virtuoso.

Seizure Freedom After Epilepsy Surgery and Higher Baseline Cognition May Be Associated With a Negatively Correlated Epilepsy Network in Temporal Lobe Epilepsy.

Background: Brain regions positively correlated with the epileptogenic zone in patients with temporal lobe epilepsy vary in spread across the brain and in the degree of correlation to the temporal lobes, thalamus, and limbic structures, and these parameters have been associated with pre-operative cognitive impairment and seizure freedom after epilepsy surgery, but negatively correlated regions have not been as well studied. We hypothesize that connectivity within a negatively correlated epilepsy network may predict which patients with temporal lobe epilepsy will respond best to surgery.Methods: Scalp EEG and resting state functional MRI (rsfMRI) were collected from 19 patients with temporal lobe epilepsy and used to estimate the irritative zone. Using patients’ rsfMRI, the negatively correlated epilepsy network was mapped by determining all the brain voxels that were negatively correlated with the voxels in the epileptogenic zone and the spread and average connectivity within the network was determined.Results: Pre-operatively, connectivity within the negatively correlated network was inversely related to the spread (diffuseness) of that network and positively associated with higher baseline verbal and logical memory. Pre-operative connectivity within the negatively correlated network was also significantly higher in patients who would go on to be seizure free.Conclusion: Patients with higher connectivity within brain regions negatively correlated with the epilepsy network had higher baseline memory function, narrower network spread, and were more likely to be seizure free after surgery.

X-ray linear dichroic ptychography

Biominerals such as seashells, coral skeletons, bone, and tooth enamel are optically anisotropic crystalline materials with unique nanoscale and microscale organization that translates into exceptional macroscopic mechanical properties, providing inspiration for engineering new and superior biomimetic structures. Using Seriatopora aculeata coral skeleton as a model, here, we experimentally demonstrate X-ray linear dichroic ptychography and map the c-axis orientations of the aragonite (CaCO3) crystals. Linear dichroic phase imaging at the oxygen K-edge energy shows strong polarization-dependent contrast and reveals the presence of both narrow (<35°) and wide (>35°) c-axis angular spread in the coral samples. These X-ray ptychography results are corroborated by four-dimensional (4D) scanning transmission electron microscopy (STEM) on the same samples. Evidence of co-oriented, but disconnected, corallite subdomains indicates jagged crystal boundaries consistent with formation by amorphous nanoparticle attachment. We expect that the combination of X-ray linear dichroic ptychography and 4D STEM could be an important multimodal tool to study nano-crystallites, interfaces, nucleation, and mineral growth of optically anisotropic materials at multiple length scales.

Unlimiting Unlimited Liability: Legal Equality for Swedish Banks with Alternative Shareholder Liability Regimes, 1897–1903

This article examines the aftermath of the 1897 Riksbank Act in Swedish banking. The act placed banks with unlimited liability and those with limited liability on equal footing, removing the note-issuing privileges of the former. We consider whether changes in risk preferences occurred subsequent to the act, or whether extended liability was a sufficient deterrent. We conclude that when legal differences were removed, lower transaction costs for unlimited liability banks (ULBs) spurred aggressive competition, reflected in narrower interest spreads relative to limited liability banks (LLBs). ULBs also took on greater leverage and held less liquidity, which supports the Coasean interpretation that the shareholder liability regime mattered little. After 1897, ULB shareholders continued to receive higher dividends, enjoyed substantially superior returns on equity, and maintained an array of corporate governance controls to shield themselves against their additional risk.

Stablecoins: Survivorship, Transactions Costs and Exchange Microstructure

Seven of the ten largest stablecoins are backed by fiat assets. The 2016 and 2017 vintages of stablecoins have failure rates of 100% and 50% respectively. More than one-third of stablecoins have failed. Tether has a 39% share of 1.77 trillion USD in 2021Q2 transactions, and USD Coin 28%. The top three stablecoins have an average velocity of 28.3. Tether transacted between 3.8 million unique addresses, 63% of the ERC-20 token network. Six of the top ten tokens have unconcentrated Herfindahl indices, but Gemini, Pax and Huobi have single holders with more than 50% of the supply. The median Tether transaction fee is similar to the cost of an ATM transaction, but they are three to four times more for Dai and USDC. Fees, which are proportional to the price of Ethereum, are rising though. Median fees for Tether rose 3,628% over the last year, and 1,897% for USD Coin. 24 hour exchange turnover in Tether is nearly $120 billion. This is comparable to the daily volume at the NYSE and almost ten times the daily flow in money market mutual funds. Narrow bid-ask spreads and depth have attracted active HFT participation.

Super-Resolution without Imaging: Library-Based Approaches Using Near-to-Far-Field Transduction by a Nanophotonic Structure.

Super-resolution imaging is often viewed in terms of engineering narrow point spread functions, but nanoscale optical metrology can be performed without real-space imaging altogether. In this paper, we investigate how partial knowledge of scattering nanostructures enables extraction of nanoscale spatial information from far-field radiation patterns. We use principal component analysis to find patterns in calibration data and use these patterns to retrieve the position of a point source of light. In an experimental realization using angle-resolved cathodoluminescence, we retrieve the light source position with an average error below λ/100. The patterns found by principal component analysis reflect the underlying scattering physics and reveal the role the scattering nanostructure plays in localization success. The technique described here is highly general and can be applied to gain insight into and perform subdiffractive parameter retrieval in various applications.

A comparison of bid-ask spread proxies and determinants of bond bid-ask spread

This paper compares performances of bid-ask spread measures and analyzes bond-level characteristics' effects on the bid-ask spread for Turkish sovereign bonds traded in Borsa Istanbul. We use intraday order data to establish a relative quoted bid-ask spread as a benchmark and compare bid-ask spread measures' estimation performances. Results show that low-frequency spread measures are able to proxy spread dynamics, and one of the measures, Closing Percent Quoted Spread, dominates others. Additionally, we use panel data analysis to examine bond characteristics’ effects on the bid-ask spread. Panel regression analysis points out that bond characteristics have a significant relation with bond liquidity. Bonds with shorter time to maturity or higher trading volume have narrower spreads. Also, bond type significantly affects the bid-ask spread.

Stock price reactivity to earnings announcements: the role of the Cammer/Krogman factors

The stock characteristics often used in securities litigation to assess market efficiency are dispositive indicators of reactivity to earnings announcements. Stocks with large capitalization, high trading volume, broad analyst coverage, a large number of market makers, and narrow bid-ask spread are far more likely to react significantly to earnings announcements than stocks without these characteristics. Univariate and multivariate tests compel this conclusion, but provide weaker evidence for analyst coverage.