Modeling asymmetric sovereign bond yield volatility with univariate GARCH models: Evidence from India

Does Indian sovereign yield volatility reflect economic fundamentals, or whether it is a self-generated force flowing through markets with little connection to such fundamentals? To answer the question, this research explores the volatility dynamics and measures the persistence of shocks to the sovereign bond yield volatility in India from 1 January 2016, to 18 May 2022, using a family of GARCH models. The empirical results indicate the high volatility persistence across the maturity spectrum in the sample period. However, upon decomposing the markets into bull and bear phases, our results support the existence of weak volatility persistence and rapid mean reversion in the bear market. This shows that the economic response policies implemented by the government during the pandemic, including fiscal measures, have a restraining effect on sovereign yield volatility. For a positive γ, the results suggest the possibility of a “leverage effect” that is markedly different from that frequently seen in stock markets. Results further indicate that the fluctuations in Indian sovereign yields cannot be dissociated from inflation and money market volatility. Our findings herein provide valuable information and implications for policymakers and financial investors worldwide

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

Background Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide.Methods A multimethods analysis was performed as part of the GlobalSurg 3 study-a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital.Findings Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3.85 [95% CI 2.58-5.75]; p<0.0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63.0% vs 82.7%; OR 0.35 [0.23-0.53]; p<0.0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer.Interpretation Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised

Comment on "Interstitial hydrogen and neutralization of shallow-donor impurities in single-crystal silicon"

It has been well established that shallow acceptor impurities in single-crystal silicon can be neutralized by exposure to monoatomic hydrogen. On the other hand, several studies have concluded that shallow donor impurities in silicon cannot be passivated. Contrary to these previous conclusions, Johnson, Herring, and Chadi1 have recently reported neutralization of phosphorus by hydrogenation. Here we show that a detailed analysis of the electrical measurements in Ref. 1 indicates that P neutralization is not necessarily implied. The results can also be explained as a combined effect of generation of H-associated acceptors in the $n^+$ layer and neutralization of substrate boron in the p region. The former reduces the effective free-electron concentration and also the effective mobility as discussed by Johnson, Herring, and Chadi. The effect of the latter is to increase the effective mobility. Since this latter effect was not taken into account in Ref. 1, donor neutralization was considered as the only possibility

Applicability of the van der Pauw-Hall measurement technique to implanted samples

The application of the van der Pauw-Hall measurement technique to implanted samples in which the mobility varies with depth has still not been fully justified. A proof that the technique is in fact applicable in this situation is given

Buckling patterns in diamond-like carbon films

An optical microscopy study of stress relief patterns in diamond-like carbon films is presented. Interesting stress relief patterns are observed which include the well-known sinusoidal type, branching pattern and string-of-beads pattern. The last one is shown to relieve stresses under marginal conditions. Two new stress relief patterns are noted in the present study. One of them is of sinusoidal shape with two extra branches at every peak position. The distribution of different stress relief forms from the outer edge of the films towards the interior is markedly dependent on the film thickness. Our new patterns support the approach in which the stress relief forms have been analysed earlier using the theory of plate buckling

Interfacial electrical properties of diamond-like carbon/gallium arsenide heterostructures

Deposition onto GaAs of dielectric film with good interracial properties is difficult owing to the high surface state densities at the GaAs surface. Study of diamond-like carbon (DLC)/GaAs heterostructures is worthwhile because of the advantageous properties of insulating DLC film and the low temperatures involved in its preparation. In this paper, we compare the electrical interfacial properties of DLC/GaAs with those of DLC/Si and DLC/Ge structures. The DLC films were prepared by r.f. plasma-assisted chemical vapour deposition using a mixture of propane and n-butane. Capacitance measurements were taken in the frequency range 400 Hz to 1 MHz. The interface trap density distribution $N_{ss}(E)$ was estimated for the DLC-Si interface using Terman's method. Compared with the DLC-Si and DLC-Ge interfaces, the DLC-GaAs interface shows qualitatively different behaviour. There is an indication that the interfacial layer at the DLC-GaAs interface is more conducting than the DLC film, giving rise to Maxwell-Wagner type relaxation. As a result, the effective permittivity of the DLC film is one order of magnitude higher. The formation of this interracial layer could be related to pre-etching of the GaAs substrate using argon plasma

Interface State Density Distribution in Amorphous/Crystalline Silicon Heterostructures

We present the first report of the interface state density distribution in undoped hydrogenated amorphous silicon/crystalline silicon heterostructures. The observed MIS (metal-insulator-semiconductor) like high frequency C(V) variation in this structure is used to obtain interface state density distribution in heterostructures with a-Si:H layer prepared either by reactive sputtering or glow discharge techniqu

High-frequency capacitance-voltage characteristics of amorphous (undoped)/crystalline silicon heterostructures

A numerical procedure is presented for calculating high-frequency capacitance variation with bias in amorphous (undoped)/crystalline silicon heterojunction. The results of the model calculations using this procedure have been reported, for different p silicon substrates. These have been compared with the corresponding capacitance variations in the other limiting case, in which the heterostructure acts like an MIS structure. The effect of interface states on the capacitance characteristics has also been studied. In the second part, we report the results of 1 MHz capacitance measurements on various amorphous (undoped)/crystalline silicon heterostructures

Vibronic model for band A emission in diamond

In this paper, recent results on band A emission in chemical vapor-deposited diamond films have been analyzed within a vibronic model. The blue-band A (2.8 eV) spectra from undoped diamond films grown by two different techniques have been simulated using the same phonon density distribution g(Ω ) and Huang-Rhys factor (S). The same g(Ω ) at higher S gives a good fit with the green band A (2.32 eV) as well. This model provides a reasonable alternative approach to the long standing donor-acceptor pair recombination model

Modelling asymmetric sovereign bond yield volatility with univariate GARCH models: Evidence from India

AbstractDoes Indian sovereign yield volatility reflect economic fundamentals, or whether it is a self-generated force flowing through markets with little connection to such fundamentals? To answer the question, this research explores the volatility dynamics and measures the persistence of shocks to the sovereign bond yield volatility in India from 1 January 2016, to 18 May 2022, using a family of GARCH models. The empirical results indicate the high volatility persistence across the maturity spectrum in the sample period. However, upon decomposing the markets into bull and bear phases, our results support the existence of weak volatility persistence and rapid mean reversion in the bear market. This shows that the economic response policies implemented by the government during the pandemic, including fiscal measures, have a restraining effect on sovereign yield volatility. For a positive γ, the results suggest the possibility of a “leverage effect” that is markedly different from that frequently seen in stock markets. Results further indicate that the fluctuations in Indian sovereign yields cannot be dissociated from inflation and money market volatility. Our findings herein provide valuable information and implications for policymakers and financial investors worldwide