Explosive Behavior Research Articles

Discovering the fundamentals of Turkish housing market: a price convergence framework

PurposeThe purpose of this study is to determine the Turkish housing price and rent dynamics among seven big cities with a unique monthly data set over 2003–2019. The secondary purpose is to examine bubble dynamics within the price convergence framework through alternative tests.Design/methodology/approachThe paper conducts two autoregressive distributed lag (ARDL) cointegration estimates for housing prices and rents and applies conditional error correction model to investigate the long-run drivers of the Turkish housing market. The authors compare ARDL cointegration in-sample forecasts and discounted cash flow (DCF) estimates with actual prices to determine the timing, magnitude and collapse period(s) of bubbles within the price convergence framework. In particular, the generalized sup augmented Dickey–Fuller (GSADF) approach time stamps multiple explosive price behaviors.FindingsThe ARDL results confirm the theory of investment value by addressing mortgage rates, the price-to-rent ratio and rents as the fundamental factors of house prices. The price-to-rent ratio offers a comparison mechanism among houses deciding to buy a new house in which rents increase monthly real estate investment returns, and mortgage rates act as the discount rate. One key finding is that these dynamics have a greater impact on house prices than mortgage rates. Furthermore, the ARDL, DCF and GSADF findings exhibit temporal overvaluations rather than bubble signals, implying that housing price appreciations, including explosive behaviors, are consistent with fundamental advances.Originality/valueThis paper is considered to be innovative in determining housing market dynamics through two different ARDL estimates for the Turkish housing price index and rents in real terms as dependent variables. The authors compare the boom and collapse periods of the real housing price index and its fundamentals via the GSADF test. A final key feature of this research is its extensive data set, with 11 different regressors between 2003 and 2019.

Audiovisual integration in the Mauthner cell enhances escape probability and reduces response latency

Fast and accurate threat detection is critical for animal survival. Reducing perceptual ambiguity by integrating multiple sources of sensory information can enhance perception and reduce response latency. However, studies addressing the link between behavioral correlates of multisensory integration and its underlying neural basis are rare. Fish that detect an urgent threat escape with an explosive behavior known as C-start. The C-start is driven by an identified neural circuit centered on the Mauthner cell, an identified neuron capable of triggering escapes in response to visual and auditory stimuli. Here we demonstrate that goldfish can integrate visual looms and brief auditory stimuli to increase C-start probability. This multisensory enhancement is inversely correlated to the salience of the stimuli, with weaker auditory cues producing a proportionally stronger multisensory effect. We also show that multisensory stimuli reduced C-start response latency, with most escapes locked to the presentation of the auditory cue. We make a direct link between behavioral data and its underlying neural mechanism by reproducing the behavioral data with an integrate-and-fire computational model of the Mauthner cell. This model of the Mauthner cell circuit suggests that excitatory inputs integrated at the soma are key elements in multisensory decision making during fast C-start escapes. This provides a simple but powerful mechanism to enhance threat detection and survival.

Explosive behavior and rational bubbles: Evidence from the Serbian hyperinflation at daily frequency

Using recently developed right-tailed sequential unit root tests at daily frequency in the extreme portion of the Serbian hyperinflation, we found that the money supply and the exchange rate exploded while the economy was approaching the maximum of the inflation tax Laffer curve, and remained explosive while on the wrong, decreasing side of that curve throughout the end of the hyperinflation. Money supply exploded as government tried first to raise seigniorage to a new higher plateau, and subsequently to prevent, albeit unsuccessfully, a decline in seigniorage while the economy was sliding down the decreasing side of the Laffer curve. The rational bubble was not found as the exchange rate explosiveness was driven by the explosiveness of its fundamental value: current and expected future money supply. Thus, even the extreme portion of the Serbian hyperinflation was driven by ever expanding money supply in the government quest for additional seigniorage and not by the rational bubbles.

Speculative bubbles and herding in cryptocurrencies

This study investigates speculative bubbles in the cryptocurrency market and factors affecting bubbles during the COVID-19 pandemic. Our results indicate that each cryptocurrency covered in the study presented bubbles. Moreover, we found that explosive behavior in one currency leads to explosivity in other cryptocurrencies. During the pandemic, herd behavior was evident among investors; however, this diminishes during bubbles, indicating that bubbles are not explained by herd behavior. Regarding cryptocurrency and market-specific factors, we found that Google Trends and volume are positively associated with predicting speculative bubbles in time-series and panel probit regressions. Hence, investors should exercise caution when investing in cryptocurrencies and follow both crypto currency and market-related factors to estimate bubbles. Alternative liquidity, volatility, and Google Trends measures are used for robustness analysis and yield similar results. Overall, our results suggest that bubble behavior is common in the cryptocurrency market, contradicting the efficient market hypothesis.

DETERMINATION OF DETONATION FRONT CURVATURE RADIUS OF ANFO EXPLOSIVES AND ITS IMPORTANCE IN NUMERICAL MODELLING OF DETONATION WITH THE WOOD-KIRKWOOD MODEL

Nitratebased commercial explosives, such as ANFO (ammonium nitrate/fuel oil mixture) and emulsion explosives, are characterized by a curved detonation front. The curvature is directly related to the rate of radial expansion of detonation products in the detonation driving zone and the rate of chemical reactions, and it is one of the characteristics of nonideal explosives. The detonation theories used to model the nonideal behaviour of explosives require both reaction rate and rate of radial expansion to be known/specified as input data. Unfortunately, neither can be measured and what is mostly used is a link between these rates and parameters which can be more easily measured. In this paper, the Wood-Kirkwood approach of determination of radial expansion through the radius of detonation front curvature and the electro-optical technique for experimental determination of detonation front curvature of ANFO explosives is applied. It was shown that an experimentally determined radius of detonation front curvature vs charge diameter, incorporated in the Wood-Kirkwood detonation theory, can satisfactorily reproduce experimental detonation velocity-charge diameter data for ANFO explosives, especially when the pressure-based reaction rate law is also calibrated (D=1.3 and k=0.06 1/(μs/GPaD)).

Explosion Behavior of Non-Uniform Methane/Air Mixture in an Obstructed Duct with Different Blockage Ratios

Explosion Behavior of Non-Uniform Methane/Air Mixture in an Obstructed Duct with Different Blockage Ratios

Explosion Behaviors of Vapor-Liquid Propylene Oxide/Air Mixture Under High-Temperature Source Ignition

Explosion Behaviors of Vapor-Liquid Propylene Oxide/Air Mixture Under High-Temperature Source Ignition

Explosive Behavior of CH4/C2H6/C3H8 Mixtures in the SAGD Process with CO2 Fusion Gases in Extra-Heavy Oil Reservoirs

Explosive Behavior of CH4/C2H6/C3H8 Mixtures in the SAGD Process with CO2 Fusion Gases in Extra-Heavy Oil Reservoirs

Structural Breaks and Explosive Behavior in the Long-Run: The Case of Australian Real House Prices, 1870–2020

Abstract In this article, we use tests of explosive behavior in real house prices with annual data for the case of Australia for the period 1870–2020. The main contribution of this paper is the use of very long time series. It is important to use longer span data because it offers more powerful econometric results. To detect episodes of potential explosive behavior in house prices over this long period, we use the recursive unit root tests for explosiveness proposed by Phillips et al. (2011), (2015a,b). According to the results, there is a clear speculative bubble behavior in real house prices between 1997 and 2020, speculative process that has not yet been adjusted.

Cointegration with structural changes and classical model of inflation in Spain, 1830–1998

In this article, we test a classical model of inflation with rational expectations for the case of Spain during the period 1830–1998. The principal testable implication is that money growth and inflation are cointegrated ruling out speculative bubbles. First, to detect episodes of potential explosive behaviour in the Spanish inflation rate, we use the recursive unit root tests for explosiveness recently proposed by Phillips et al. (2011), and Phillips et al. (2015a, 2015b). Second, we consider the possibility that a linear cointegrated regression model with multiple structural changes would provide a good empirical description of the classical model of inflation for Spain over this long period. Our methodology is based on the instability tests recently proposed in Kejriwal and Perron (2008, 2010) as well as the cointegration tests developed in Arai and Kurozumi (2007) and Kejriwal (2008).

IDENTIFICATION OF MULTIPLE BUBBLES IN TURKISH FINANCIAL MARKETS: EVIDENCE FROM GSADF APPROACH

This study examines the explosive behavior in the five local market prices of stock indices (in USD and TRY), 
 bond, CDS, gold, and currency exchange rate of USDTRY at weekly observations over the sample period 
 between 2005 and 2021. We find strong evidence of bubble formations in bond, gold, and currency markets 
 during the crisis (financial and pandemic, such as ongoing COVID-19 outbreak) and non-crisis periods. 
 The findings show both unidirectional and bidirectional causal linkages under the homoscedasticity and 
 heteroscedasticity assumptions. Additionally, the causation is most pronounced under the homoscedastic 
 model between the currency market with the CDS, gold, and stock markets.

Increased Gray Matter Density in the Right Mesencephalic Tegmentum Is Associated With Better Engel Classes I and II After Radiosurgery for Hypothalamic Hamartomas.

Hypothalamic hamartomas (HHs) are disabling congenital lesions, responsible for gelastic seizures frequently associated with catastrophic epilepsies, epileptogenic encephalopathy, and cognitive and psychiatric severe comorbidities. Stereotactic radiosurgery (SRS) is a well-established minimally invasive therapeutic approach. To assess whether pretherapeutic gray matter density (GMD) correlates with seizure outcome. We used voxel-based morphometry at whole-brain level, as depicted on pretherapeutic standard structural magnetic resonance neuroimaging. We examined 24 patients (10 male patients, 14 female patients; mean age, 12.7 yr; median, 9; range, 5.9-50) treated in Marseille University Hospital, France, between May 2001 and August 2018. Most relevant anatomic area predicting postoperative Engel classes I and II vs III and IV after SRS for HHs was mesencephalic tegmentum. Higher pretherapeutic GMD in this area was associated with better outcomes for seizure cessation. The only other statistically significant clusters were right cerebellar lobule VIIIb and VIIIa. Lower pretherapeutic GMD in both clusters correlated with better Engel class outcomes. GMD decreased with age in the left mediodorsal thalamus. Seizure cessation after SRS for HHs was associated with higher GMD in mesencephalic tegmental area, acknowledged to be involved in the neural control of explosive vocal behavior in animals. This area is connected by the mamillotegmental bundle to the lateral tuberal nucleus area of the hypothalamus, where HHs are known to rise. In the future, the detection of more gray matter in this "laugh" tegmental area based on pretherapeutic routine structural neuroimaging might help in patient selection for minimally invasive radiosurgery for HH.

Unit-root tests for explosive behavior

We present a new command, radf, that tests for explosive behavior in time series. The command computes the right-tail augmented Dickey and Fuller (1979, Journal of the American Statistical Association 74: 427–431) unitroot test and its further developments based on supremum statistics derived from augmented Dickey–Fuller-type regressions estimated using recursive windows (Phillips, Wu, and Yu, 2011, International Economic Review 52: 201–226) and recursive flexible windows (Phillips, Shi, and Yu, 2015, International Economic Review 56: 1043–1078). It allows for the lag length in the test regression and the width of rolling windows to be either specified by the user or determined using data-dependent procedures, and it performs the date-stamping procedures advocated by Phillips, Wu, and Yu (2011) and Phillips, Shi, and Yu (2015) to identify episodes of explosive behavior. It also implements the wild bootstrap proposed by Phillips and Shi (2020, Handbook of Statistics: Financial, Macro and Micro Econometrics Using R, Vol. 42, 61–80) to lessen the potential effects of unconditional heteroskedasticity and account for the multiplicity issue in recursive testing. The use of radf is illustrated with an empirical example.

Detecting periodically collapsing bubbles in the S&P 500

Two robust tests on S&P 500 data show evidence of bubbles. A test of stationarity controlling for skewness and excess kurtosis is designed to detect periodically collapsing rational bubbles. Test for cointegration and direct tests on the price-dividend and price-earnings ratios cannot reject non-stationarity for all the samples considered. A test for explosive behavior on rolling window of the data also provide evidence of multiple bubbles and allow for dating of bubbles using the same set of variables. The two bubble episodes detected in all relevant cases are associated with the Spanish Flu in 1917 and the housing crisis in 2008.

Dynamic shearing resistance of a polymer-bonded energetic simulant: Composite of sucrose and hydroxyl-terminated polybutadiene (HTPB)

The mechanical behavior of polymer-bonded explosives (PBXs) and polymer-bonded simulants has been widely studied under normal impact. However, their shearing response under large pressures and shear strain-rates has not been explored, to the best of our knowledge. Such measurements are crucial in informing constitutive models that aim to predict hot-spot formation and ignition behavior of PBXs subject to multi-axial loading. Pressure-shear plate impact experiments have been conducted on a composite of hydroxyl-terminated polybutadiene (HTPB) binder and sucrose (an energetic simulant) under normal stresses of 3–10 GPa nominally and shear strain-rates of the order of 105 s−1. The shear strength of the composite shows a dramatic drop after reaching a critical shear strain. Such a drop could be due to fracture or localization in either of the two phases, further compounded by other mechanisms such as friction between the resulting interfaces or collapse of voids. It is also observed that the shear strength of the composite is highly pressure-sensitive, increasing from 176 to 453MPa as the normal stress increases nominally from 3 to 9.5 GPa. Comparison of the shearing behavior of the composite with that of a granular aggregate of sucrose grains at low normal stresses (∼3 GPa) indicates that the binder plays the role of a lubricant between the sucrose grains at those normal stresses. However, at normal stresses of ∼9–10 GPa, the shear strength of HTPB becomes similar to sucrose, and beyond these normal stresses, a transition in the failure mode and its location is expected.

Spacetime expansion in the presence of a background velocity field

In this article, we introduce a new metric assuming an additional velocity-based term in a spacetime metric. Although the inclusion of this additional phrase can indicate that the Lorentz symmetry has broken, the results of null geodesics demonstrate that the amount of variation in the speed of light is considerably smaller than what can be observed. This article delves into the primary use of this additional phrase in the expansion development of Minkowski and de Sitter spacetimes. The findings indicate that multiple versions of the velocity function may explain the universe's initial explosion and expansion behavior even before the inflation epoch, the inflation itself, and the universe's positive acceleration in late time cosmology without dark matter or dark energy. These models can also rebuild primordial black holes in the early universe as an alternative to dark matter.

Gas-air mixture explosion behaviour research at different temperatures

This article discusses gas-air mixture explosion properties depending on its initial parameters. Authors use the heat flow control sensor to obtain the most dangerous concentration range at normal and low temperatures. The dependences of heat flux changes at initial moment of explosion under different conditions are analyzed. The survey setup was a plastic bag filled with a gas mixture. Experiments were carried out with (without) holding the substance and with (without) using the turbulators. The reliability of acquired data was assessed by running a tenfold repetition of each test bench under identical meteorological conditions.

Real Estate Bubbles and Contagion: Evidence from Selected European Countries

Using quarterly housing price-to-rent ratios from 1970 to 2018, this paper investigated the presence of real estate bubbles at a national level in eight selected European countries, namely Belgium, France, Germany, Italy, the Netherlands, Portugal, Spain, and the United Kingdom. Then, we analyzed bubbles contagion among these countries. We applied the generalized sup ADF test developed by Phillips et al. (2015) to detect explosive behavior in house prices. Subsequently, we implemented the non-parametric model with time varying coefficients developed by Greenaway-McGrevy and Phillips (2016) to estimate bubbles contagion among European real estate markets. We found evidence of at least one historical bubble in all these countries, with Germany, the Netherlands, Portugal, and Spain currently experiencing a rising bubble. The results also suggest that bubbles are contagious between these real estate markets.

An Application of Damped Diffusion for Modeling Volatility Dynamics

Abstract This paper proposes a damped constant elasticity variance (CEV) stochastic volatility (DCEV) model, which remedies the possible explosive behavior of the CEV model and also accommodates the mean-reverting dynamics more appropriately than the nonlinear drift (NLD) stochastic volatility model. As the DCEV model maintains the linear drift, an analytic formula is available to efficiently infer latent variances from VIX levels, after which both its physical and risk-neutral parameters can be simultaneously estimated with the maximum-likelihood approach given S&P 500 returns and inferred variances. The DCEV model outperforms the CEV and NLD models in in-sample fitting performance and in out-of-sample variance forecasting under the physical measure. It also exhibits superior ability in out-of-sample option pricing over the CEV and Heston’s (1993) models under the risk-neutral measure. This satisfactory performance demonstrates the suitability of describing volatility dynamics with the DCEV model and the potential of applying this to study other issues.

Moving for safety: a qualitative analysis of affected communities\u2019 evacuation response during the 2014 Mayon Volcano eruption

This study looks at the 2014 Mayon Volcano eruption to identify possible factors that contribute to the actions that people (local authorities/officials, community leaders, and residents) take during an eruptive period. We used qualitative analysis to examine interviews of people who experienced the August–December 2014 Mayon Volcano unrest, to determine the nature of people’s understanding of hazards and risks, their decision-making, and response process. The thematic analysis shows that residents reacted to the information given to them in several ways- they evacuated when ordered (mandatory), chose not to evacuate for various reasons (e.g. they did not believe they are in danger citing experiences, inconvenience in evacuation sites, etc.), and evacuated even when not ordered to (voluntary). The local officials and community leaders were asked about their views on the possible reasons or motivations as to why residents would evacuate, and common themes that emerged were fear emanating from the experience of past eruptions, obeying the order to evacuate because it is the law, and order from provincial authorities (setting aside personal opinion on the state of the volcano based on experiential knowledge), and the potential to receive relief goods for those who are economically in need. This paper also looks at the challenges to local officials when an eruptive episode occurs- but the event falls short of the expected typical explosive behavior from the volcano. This study argues for people’s experiential knowledge as an important factor in shaping views about hazards and risks that leads to the decision-making of individuals and its importance in risk communication strategies.