Essays on Stock Performance, Asset Prices, and Financial Stability of Insurers

This dissertation contributes to the discussion on the existence and extent of systemic risk in the insurance sector and its regulation. It consists of four self-contained empirical studies. Chapter one contains the introduction and motivation. The second chapter addresses the question of what characteristics an insurer exhibits such that it contributes to potential financial sector instability. The study analyzes stock losses of U.S. insurers and the U.S. financial market during the financial crisis of 2008, and examines idiosyncratic characteristics proposed by regulators to identify systemically important insurers. It employs three well-known measures of systemic risk in cross-sectional and probit regressions. Chapter three examines the relation between asset price bubbles and systemic risk among a global sample of insurance companies over a period of almost thirty years. The fourth chapter focuses on how stock market investors evaluate the presence of systemic risk in the U.S. insurance sector, and whether they price in indicators of systemic risk in insurer stocks. This study employs five different asset pricing models over time periods before, during, and after the financial crisis of 2008. The fifth chapter analyzes the relation between insurers' capital and their profitability around the world over a nine-year period. Causality between the measures of capital and profitability is established using an instrumental variable approach

Why do some insurers become systemically relevant?

Are some insurers relevant for the stability of the financial system? And if yes, what firm fundamentals and aspects of insurers’ business models cause them to destabilize an entire financial sector? We find that several insurers did indeed contribute significantly to the instability of the U.S. financial sector during the recent financial crisis. We empirically confirm that insurers that were most exposed to systemic risk were larger, relied more heavily on non-policyholder liabilities and had higher ratios of investment income to net revenues on average. Contrary to current conjectures of insurance regulators, we find that the contribution of insurers to systemic risk is only driven by insurer size

Competition, efficiency and soundness in European life insurance markets

This paper provides cross-country evidence on the association between soundness and competition in the life insurance industry, where competition is measured by the Boone indicator. We analyze 10 European Union (EU) life insurance markets over the post-deregulation period 1999-2011. The results indicate that competition increases the soundness of the EU life insurance markets. Since the Boone indicator measures competition based on the reallocation of profits from inefficient insurers to efficient ones, our results suggest that efficiency is the mechanism through which competition contributes to insurer solvency. The soundness-enhancing effect of competition is greater for weak insurers than for healthy ones

Tinnitus Perception and Distress Is Related to Abnormal Spontaneous Brain Activity as Measured by Magnetoencephalography

BACKGROUND: The neurophysiological mechanisms underlying tinnitus perception are not well understood. Surprisingly, there have been no group studies comparing abnormalities in ongoing, spontaneous neuronal activity in individuals with and without tinnitus perception. METHODS AND FINDINGS: Here, we show that the spontaneous neuronal activity of a group of individuals with tinnitus (n = 17) is characterised by a marked reduction in alpha (8–12 Hz) power together with an enhancement in delta (1.5–4 Hz) as compared to a normal hearing control group (n = 16). This pattern was especially pronounced for temporal regions. Moreover, correlations with tinnitus-related distress revealed strong associations with this abnormal spontaneous activity pattern, particularly in right temporal and left frontal areas. Overall, effects were stronger for the alpha than for the delta frequency band. A data stream of 5 min, recorded with a whole-head neuromagnetometer under a resting condition, was sufficient to extract the marked differences. CONCLUSIONS: Despite some limitations, there are arguments that the regional pattern of abnormal spontaneous activity we found could reflect a tinnitus-related cortical network. This finding, which suggests that a neurofeedback approach could reduce the adverse effects of this disturbing condition, could have important implications for the treatment of tinnitus

Stereotactic, single-dose irradiation of stage I non-small cell lung cancer and lung metastases

BACKGROUND: We prospectively reviewed response rates, local control, and side effects after non-fractionated stereotactic high single-dose body radiation therapy for lung tumors. METHODS: Fifty-eight patients underwent radiosurgery involving single-dose irradiation. With 25 patients, 31 metastases in the lungs were irradiated; with each of 33 patients, stage I non-small cell lung cancer (NSCLC) was subject to irradiation. The standard dose prescribed to the isocenter was 30 Gy with an axial safety margin of 10 mm and a longitudinal safety margin of 15 mm. The planning target volume (PTV) was defined using three CT scans with reference to the phases of respiration so that the movement span of the clinical target volume (CTV) was enclosed. RESULTS: The volume of the metastases (CTV) varied from 2.8 to 55.8 cm(3 )(median: 6.0 cm(3)) and the PTV varied from 12.2 to 184.0 cm(3 )(median: 45.0 cm(3)). The metastases ranged from 0.7 to 4.5 cm in largest diameter. The volume of the bronchial carcinomas varied from 4.2 to 125.4 cm(3)(median: 17.5 cm(3)) and the PTV from 15.6 to 387.3 cm(3 )(median: 99.8 cm(3)). The bronchial carcinomas ranged from 1.7 to 10 cm in largest diameter. Follow-up periods varied from 6.8 to 63 months (median: 22 months for metastases and 18 months for NSCLC). Local control was achieved with 94% of NSCLC and 87% of metastases. No serious symptomatic side effects were observed. According to the Kaplan-Meier method the overall survival probability rates of patients with lung metastases were as follows: 1 year: 97%, 2 years: 73%, 3 years: 42%, 4 years: 42%, 5 years: 42% (median survival: 26 months); of those with NSCLC: 1 year: 83%, 2 years: 63%, 3 years: 53%, 4 years: 39%: (median survival: 20.4 months). CONCLUSION: Non-fractionated single-dose irradiation of metastases in the lungs or of small, peripheral bronchial carcinomas is an effective and safe form of local treatment and might become a viable alternative to invasive techniques

Transient reduction of tinnitus intensity is marked by concomitant reductions of delta band power

<p>Abstract</p> <p>Background</p> <p>Tinnitus is an auditory phantom phenomenon characterized by the sensation of sounds without objectively identifiable sound sources. To date, its causes are not well understood. Previous research found altered patterns of spontaneous brain activity in chronic tinnitus sufferers compared to healthy controls, yet it is unknown whether these abnormal oscillatory patterns are causally related to the tinnitus sensation. Partial support for this notion comes from a neurofeedback approach developed by our group, in which significant reductions in tinnitus loudness could be achieved in patients who successfully normalized their patterns of spontaneous brain activity. The current work attempts to complement these studies by scrutinizing how modulations of tinnitus intensity alter ongoing oscillatory activity.</p> <p>Results</p> <p>In the present study the relation between tinnitus sensation and spontaneous brain activity was investigated using residual inhibition (RI) to reduce tinnitus intensity and source-space projected magnetencephalographic (MEG) data to index brain activity. RI is the sustained reduction (criteria: 50% for at least 30 s) in tinnitus loudness after cessation of a tonal tinnitus masker. A pilot study (n = 38) identified 10 patients who showed RI. A significant reduction of power in the delta (1.3–4.0 Hz) frequency band was observed in temporal regions during RI (p ≤ 0.001).</p> <p>Conclusion</p> <p>The current results suggest that changes of tinnitus intensity induced by RI are mediated by alterations in the pathological patterns of spontaneous brain activity, specifically a reduction of delta activity. Delta activity is a characteristic oscillatory activity generated by deafferented/deprived neuronal networks. This implies that RI effects might reflect the transient reestablishment of balance between excitatory and inhibitory neuronal assemblies, via reafferentation, that have been perturbed (in most tinnitus individuals) by hearing damage. As enhancements have been reported in the delta frequency band for tinnitus at rest, this result conforms to our assumption that a normalization of oscillatory properties of cortical networks is a prerequisite for attenuating the tinnitus sensation. For RI to have therapeutic significance however, this normalization would have to be stabilized.</p

Abnormal resting-state cortical coupling in chronic tinnitus

<p>Abstract</p> <p>Background</p> <p>Subjective tinnitus is characterized by an auditory phantom perception in the absence of any physical sound source. Consequently, in a quiet environment, tinnitus patients differ from control participants because they constantly perceive a sound whereas controls do not. We hypothesized that this difference is expressed by differential activation of distributed cortical networks.</p> <p>Results</p> <p>The analysis was based on a sample of 41 participants: 21 patients with chronic tinnitus and 20 healthy control participants. To investigate the architecture of these networks, we used phase locking analysis in the 1–90 Hz frequency range of a minute of resting-state MEG recording. We found: 1) For tinnitus patients: A significant decrease of inter-areal coupling in the alpha (9–12 Hz) band and an increase of inter-areal coupling in the 48–54 Hz gamma frequency range relative to the control group. 2) For both groups: an inverse relationship (r = -.71) of the alpha and gamma network coupling. 3) A discrimination of 83% between the patient and the control group based on the alpha and gamma networks. 4) An effect of manifestation on the distribution of the gamma network: In patients with a tinnitus history of less than 4 years, the left temporal cortex was predominant in the gamma network whereas in patients with tinnitus duration of more than 4 years, the gamma network was more widely distributed including more frontal and parietal regions.</p> <p>Conclusion</p> <p>In the here presented data set we found strong support for an alteration of long-range coupling in tinnitus. Long-range coupling in the alpha frequency band was decreased for tinnitus patients while long-range gamma coupling was increased. These changes discriminate well between tinnitus and control participants. We propose a tinnitus model that integrates this finding in the current knowledge about tinnitus. Furthermore we discuss the impact of this finding to tinnitus therapies using Transcranial Magnetic Stimulation (TMS).</p

Tinnitus Intensity Dependent Gamma Oscillations of the Contralateral Auditory Cortex

Non-pulsatile tinnitus is considered a subjective auditory phantom phenomenon present in 10 to 15% of the population. Tinnitus as a phantom phenomenon is related to hyperactivity and reorganization of the auditory cortex. Magnetoencephalography studies demonstrate a correlation between gamma band activity in the contralateral auditory cortex and the presence of tinnitus. The present study aims to investigate the relation between objective gamma-band activity in the contralateral auditory cortex and subjective tinnitus loudness scores. In unilateral tinnitus patients (N = 15; 10 right, 5 left) source analysis of resting state electroencephalographic gamma band oscillations shows a strong positive correlation with Visual Analogue Scale loudness scores in the contralateral auditory cortex (max r = 0.73, p<0.05). Auditory phantom percepts thus show similar sound level dependent activation of the contralateral auditory cortex as observed in normal audition. In view of recent consciousness models and tinnitus network models these results suggest tinnitus loudness is coded by gamma band activity in the contralateral auditory cortex but might not, by itself, be responsible for tinnitus perception

Future buildings as carbon sinks: Comparative analysis of timber-based building typologies regarding their carbon emissions and storage

The building and construction sector is responsible for a large share of carbon emissions resulting in the need to reduce them to mitigate climate change. Timber construction methods promise to lower emissions combined with biogenic carbon storage in the built environment. While there are several studies comparing the emissions of mineral-based and timber-based buildings, a consistent comparison of different timber-based building assemblies is still missing. This study compares carbon emissions from material production and carbon storage capabilities of four timber-based and two brick and reinforced concrete building assemblies. These assemblies were designed for a residential multi-storey building in Berlin, Germany. To compare and rank the carbon impacts of these assemblies we introduce a carbon storage-to-emission ratio. The calculations were performed using a Carbon Cycle Assessment Model implementation in Python. The results indicate an average reduction in carbon emissions of timber-based building assemblies by 32.6% to “Brick” and 40.4% to “Reinforced Concrete”, respectively. Across the timber-based building assemblies, the carbon emissions range between 85 t and 115 t, leading to an average of 105 t per building. Pronounced differences were observed in carbon storage, with the “Dowel Laminated Timber” building assembly storing more than three times the amount of carbon compared to “Light Weight Timber” assembly. To further reduce emissions from buildings and the construction sector and potentially enhance urban carbon storage, “Glue Laminated Timber” and “Dowel Laminated Timber” building assemblies were identified as the most promising