624 research outputs found
Evidence on the Lack of Separation between Business and Personal Risks among Small Businesses
Small business researchers conjecture that there is little separation between business and personal risks among small businesses. Personal assets and wealth can be subject to business risks in the form of an implicit or explicit claim depending on the organizational form and whether personal commitments are pledged by owners. The choice of organizational form can be considered a mechanism to increase the degree of separation; however, lenders\u27 requirements for personal commitments mitigate the benefits of limited liability provisions. This paper examines the role of personal collateral and personal guarantees in augmenting implicit claims on business and personal assets with explicit claims on personal assets and personal wealth. We document the degree of non-separation of business and personal risks for 692 firms. Our results suggests that small business owners have a significant incidence of personal assets and wealth pledged for business loans, even for organizational forms such as S-corporations and C-corporations with limited legal liability. These results confirm the conjecture that there is a lack of separation between business and personal risks. The lack of separation of business and personal risks has important policy implications for the borrowing patterns and access to credit markets of small businesses
Si:SrTiO3-Al2O3-Si:SrTiO3 multi-dielectric architecture for metal-insulator-metal capacitor applications
Metal-insulator-metal (MIM) capacitors comprised of amorphous Si:SrTiO3-Al2O3-Si:SrTiO3 multi-dielectric architecture have been fabricated employing a combination of pulsed laser and atomic layer deposition techniques. The voltage linearity, temperature coefficients of capacitance, dielectric and electrical properties upon thickness were studied under a wide range of temperature (200 – 400 K) and electric field stress (± 1.5 MV/cm). A high capacitance density of 31 fF/µm2, a low voltage coefficient of capacitance of 363 ppm/V2, a low temperature coefficient of capacitance of < 644 ppm/K and an effective dielectric constant of ~133 are demonstrated in a MIM capacitor with ~1.4 nm capacitance equivalent thickness in a ~40 nm thick ultra high-k multi-dielectric stack. All of these properties make this dielectric architecture of interest for next generation highly scaled MIM capacitor applications.PostprintPeer reviewe
Experimental verification of the ab initio phase transition sequence in SrZrO3 and comparisons with SrHfO3 and SrSnO3
AK acknowledges the CSIR-National Physical Laboratoryinternal net work project, INDIA. Hitesh Borkar would like to acknowledge the CSIR (SRF) to provide fellowship to carry out PhD program.We present detailed Raman studies of SrZrO3 (SZO) that show three anomalies in Raman modes:One has a small jump in frequency ω; one has its intensity vanish; and a third has a sharp change in temperature derivative dω(T)/dT from flat below T = 600 K to a Curie-Weiss dependence above 600 K with extrapolation to zero frequency at the known transition temperature T = 970K, thereby proving the latter to be displacive. In addition, the P4mm ferroelectric phase predicted at high stresses [Amisi et al., Phy. Rev. B 85, 064112 (2012)] has preliminary support from polarization-voltage experiments. The inference of a new transition in the temperature region 600-650 K is in disagreement with neutron studies. Comparisons are given for family member SrSnO3 and SrHfO3, and we discuss the different conclusions of Kennedy and Knight, J Phys.Condens. Mat. 27, 365401 (2015). We show that a known transition in SrHfO3 is also displacive with a well-behaved soft mode.Publisher PDFPeer reviewe
Development of a telescope for medium-energy gamma-ray astronomy
The Advanced Energetic Pair Telescope (AdEPT) is being developed at GSFC as a future NASA MIDEX mission to explore the medium-energy (5–200 MeV) gamma-ray range. The enabling technology for AdEPT is the Three- Dimensional Track Imager (3-DTI), a gaseous time projection chamber. The high spatial resolution 3-D electron tracking of 3-DTI enables AdEPT to achieve high angular resolution gamma-ray imaging via pair production and triplet production (pair production on electrons) in the medium-energy range. The low density and high spatial resolution of 3-DTI allows the electron positron track directions to be measured before they are dominated by Coulomb scattering. Further, the significant reduction of Coulomb scattering allows AdEPT to be the first medium-energy gamma-ray telescope to have high gamma-ray polarization sensitivity. We review the science goals that can be addressed with a medium-energy pair telescope, how these goals drive the telescope design, and the realization of this design with AdEPT. The AdEPT telescope for a future MIDEX mission is envisioned as a 8 m3 active volume filled with argon at 2 atm. The design and performance of the 3-DTI detectors for the AdEPT telescope are described as well as the outstanding instrument challenges that need to be met for the AdEPT mission
Effect of thickness on dielectric, ferroelectric, and optical properties of Ni substituted Pb(Zr0.2Ti0.8)O3 thin films
This work was supported by NSF Grant EPS-01002410. N. Ortega acknowledges support from the DoE Grant DE-FG02-08ER46526.We report thickness dependent dielectric,ferroelectric, and optical properties of Ni substituted Pb(Zr0.2Ti0.8)O3 thin films. The Pb(Zr0.2Ti0.8)0.70Ni0.30O3−δ (PZTNi30) thin films for various thicknesses, ranging from 5 nm to 400 nm, were fabricated by pulsed laser deposition technique. Giant dielectric dispersion, low dielectric loss, large dielectric constant -1000–1500 from 100 Hz to 100 kHz, and diffused dielectric anomaly near 570–630 K were observed in PZTNi30 thin films. These films show well saturated ferroelectric hysteresis, with large remanent polarization. It also illustrated excellent optical transparency which decreased from 82 to 72% with increasing film thickness from 5 nm to 400 nm for the probe wavelengths ranging from 200 to 1100 nm. A decrease in direct bandgap (Eg) values from 4 eV to 3.4 eV and indirect-Eg values from 3.5 eV to 2.9 eV were observed for PZTNi30 thin films with increase in film thickness from 5 nm to 400 nm, respectively. The direct and indirect bandgaps were discussed in context of film thickness and grain size effects. Our investigations on optical properties of PZTNi30 thin films suggest that bandgap can be modified as a function of film thickness which may be useful for readers working to develop novel candidates for ferroelectric photovoltaic.Publisher PDFPeer reviewe
Incommensurate-commensurate transition in the geometric ferroelectric LaTaO4
Funding: UK Engineering and Physical Sciences Research Council (Grant Number(s): EP/P022637/1, EP/K503162/1), Science and Technology Facilities Council (Grant Number(s): RB1820307), China Scholarship Council (CN).The layered perovskite LaTaO4 has been synthesized to be stable in both (polar) orthorhombic and (nonpolar) monoclinic polymorphs at ambient conditions. Although the structural transition between monoclinic and orthorhombic phases has been well established, there is some controversy regarding a further, unidentified transition around 500 K. Here this is identified as an incommensurate–commensurate first‐order transition between incommensurate Cmc21(α00)0s0 and commensurate Cmc21 orthorhombic phases. Transmission electron microscopy indicates partially ordered stacking of different structural units in a, identifying the local cause for the modulation, whereas variable temperature powder neutron diffraction has shown the overall macroscopic modulation vector, q ≈ (0.456, 0, 0)—roughly a 2.2 × expansion in a, corresponding to an approximate 11a commensurate superunit cell dimension. The modulation shows a continuous temperature dependence until transitioning to the basic (commensurate) cell at TIC‐C. Doping the interlayer La sites with smaller Nd cations stabilizes the incommensuration to higher temperature, suggesting the modulation is geometrically driven at the A site.Publisher PDFPeer reviewe
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Cardiac Biomarkers and Risk of Atrial Fibrillation in Chronic Kidney Disease: The CRIC Study.
Background We tested associations of cardiac biomarkers of myocardial stretch, injury, inflammation, and fibrosis with the risk of incident atrial fibrillation (AF) in a prospective study of chronic kidney disease patients. Methods and Results The study sample was 3053 participants with chronic kidney disease in the multicenter CRIC (Chronic Renal Insufficiency Cohort) study who were not identified as having AF at baseline. Cardiac biomarkers, measured at baseline, were NT-proBNP (N-terminal pro-B-type natriuretic peptide), high-sensitivity troponin T, galectin-3, growth differentiation factor-15, and soluble ST-2. Incident AF ("AF event") was defined as a hospitalization for AF. During a median follow-up of 8 years, 279 (9%) participants developed a new AF event. In adjusted models, higher baseline log-transformed NT-proBNP (N-terminal pro-B-type natriuretic peptide) was associated with incident AF (adjusted hazard ratio [HR] per SD higher concentration: 2.11; 95% CI, 1.75, 2.55), as was log-high-sensitivity troponin T (HR 1.42; 95% CI, 1.20, 1.68). These associations showed a dose-response relationship in categorical analyses. Although log-soluble ST-2 was associated with AF risk in continuous models (HR per SD higher concentration 1.35; 95% CI, 1.16, 1.58), this association was not consistent in categorical analyses. Log-galectin-3 (HR 1.05; 95% CI, 0.91, 1.22) and log-growth differentiation factor-15 (HR 1.16; 95% CI, 0.96, 1.40) were not significantly associated with incident AF. Conclusions We found strong associations between higher NT-proBNP (N-terminal pro-B-type natriuretic peptide) and high-sensitivity troponin T concentrations, and the risk of incident AF in a large cohort of participants with chronic kidney disease. Increased atrial myocardial stretch and myocardial cell injury may be implicated in the high burden of AF in patients with chronic kidney disease
Ferroelectric photovoltaic properties in doubly substituted (Bi0.9La0.1)(Fe0.97Ta0.03)O3 thin films
This work was supported by the DOE-EPSCoR Grant No. DE-FG02-08ER46526. Acknowledgment is also due to NSF Grant No. #1002410 for providing fellowships to R.K.K., D.B., and J.S.Y.Doubly substituted [Bi0.9La0.1][Fe0.97Ta0.03]O3 (BLFTO) films were fabricated on Pt/TiO2/SiO2/Si substrates by pulsed laser deposition. The ferroelectric photovoltaic properties of ZnO:Al/BLFTO/Pt thin film capacitor structures were evaluated under white light illumination. The open circuit voltage and short circuit current density were observed to be ∼0.20 V and ∼1.35 mA/cm2, respectively. The band gap of the films was determined to be ∼2.66 eV, slightly less than that of pure BiFeO3 (2.67 eV). The PVproperties of BLFTO thin films were also studied for various pairs of planar electrodes in different directions in polycrystalline thin films.Publisher PDFPeer reviewe
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