Thomas Barnebeck Andersen

Thermo-optic control of dielectric-loaded plasmonic waveguide components

We report preliminary results on the development of compact (length < 100 microm) fiber-coupled dielectric-loaded plasmonic waveguide components, including Mach-Zehnder interferometers (MZIs), waveguide-ring resonators (WRRs) and directional couplers (DCs), whose operation at telecom wavelengths is controlled via the thermo-optic effect by electrically heating the gold stripes of dielectric-loaded plasmonic waveguides. Strong output modulation (> 20%) is demonstrated with MZI- and WRR-based components, and efficient (approximately 30%) rerouting is achieved with DC switches.

US politics and World Bank IDA-lending

Abstract This paper studies the role of US political factors in the allocation of World Bank concessional lending, where US political interests are proxied by voting similarity in the United Nations General Assembly on issues identified as important by the US Department of State. In contrast to previous studies we find that the US exerted a significant influence on IDA lending during the period 1993–2000. We demonstrate that the influence was both statistically as well as economically significant. Finally, we demonstrate that our result is robust with respect to the omission of the IDA Country Performance Rating index.

Power monitoring in dielectric-loaded surface plasmon-polariton waveguides

We report on propagating mode power monitoring in dielectric-loaded surface plasmon-polariton waveguides (DLSPPWs) by measuring the resistance of gold stripes supporting the DLSPPW mode propagation. Inevitable absorption of the DLSPPW mode in metal causes an increase in the stripe temperature and, thereby, in its resistance whose variations are monitored with an external Wheatstone bridge being accurately balanced in the absence of radiation in a waveguide. The investigated waveguide configuration consists of a 1-µm-thick and 10-µm-wide polymer ridges tapered laterally to a 1-µm-wide ridge placed on a 50-nm-thin and 4-µm-wide gold stripe, all supported by a magnesium fluoride substrate. Using single-mode polarization-maintaining fiber for in- and out-coupling of radiation, DLSPPW mode power monitoring at telecom wavelengths is realized with the responsivities of up to ~1.8 µV/µW (showing weak wavelength dependence) being evaluated for a bias voltage of 1 V.

Pre-Reformation Roots of the Protestant Ethic

We hypothesize that cultural appreciation of hard work and thrift,the Protestant ethic according to Max Weber,had a pre-Reformation origin.The proximate source of these values was,according to the proposed theory,the Catholic Order of Cistercians.In support,we first document an impact from the Order on growth within the epicenter of the industrial revolution;English counties that were more exposed to Cistercian monasteries experienced faster productivity growth from the 13th century onwards. Consistent with a cultural influence,this impact is also found after the monasteries were dissolved in the 1530s.Second,we find that the values emphasized by Weber are relatively more pervasive in European regions where Cistercian monasteries were located historically,and that the legacy of the Cistercianscan be detected inpresent-day employment rates across European sub-regions.

Walking the talk: the need for a trial registry for development interventions

Recent advances in the use of randomised control trials to evaluate the effect of development interventions promise to enhance our knowledge of what works and why. A core argument supporting randomised studies is the claim that they have high internal validity. The authors argue that this claim is weak as long as a trial registry of development interventions is not in place. Without a trial registry, the possibilities for data mining, created by analyses of multiple outcomes and subgroups, undermine internal validity. Drawing on experience from evidence-based medicine and recent examples from microfinance, they argue that a trial registry would also enhance external validity and foster innovative research.

Eye Disease and Development

This research advances the hypothesis that cross-country variation in the historical incidence of eye disease has influenced the current global distribution of per capita income. The theory is that pervasive eye disease diminished the incentive to accumulate skills, thereby delaying the fertility transition and the take-off to sustained economic growth. In order to estimate the influence from eye disease incidence empirically, we draw on an important fact from the field of epidemiology: Exposure to solar ultraviolet B radiation (UVB-R) is an underlying determinant of several forms of eye disease; the most important being cataract, which is currently the leading cause of blindness worldwide. Using a satellite-based measure of UVB-R, we document that societies more exposed to UVB-R are poorer and underwent the fertility transition with a significant delay compared to the forerunners. These findings are robust to the inclusion of an extensive set of climate and geography controls. Moreover, using a global data set on economic activity for all terrestrial grid cells we show that the link between UVB-R and economic development survives the inclusion of country fixed effect.

Nanoscale phase behavior on flat and curved membranes

The diverse physical properties of membranes play a critical role in many membrane associated biological processes. Proteins responsible for membrane transport can be affected by the lateral membrane order and lateral segregation of proteins is often controlled by the preference of certain membrane anchors for membrane phases having a physically ordered state. The dynamic properties of coexisting membrane phases are often studied by investigating their thermal behavior. Optical trapping of gold nanoparticles is a useful tool to generate local phase transitions in membranes. The high local temperatures surrounding an irradiated gold nanoparticle can be used to melt a part of a giant unilamellar lipid vesicle (GUV) which is then imaged using phase sensitive fluorophores embedded within the bilayer. By local melting of GUVs we reveal how a protein-free, one component lipid bilayer can mediate passive transport of fluorescent molecules by localized and transient pore formation. Also, we show how tubular membrane curvatures can be generated by optical pulling from the melted region on the GUV. This will allow us to measure the effect of membrane curvature on the phase transition temperature.

Lightning, IT Diffusion and Economic Growth Across US States

Empirically, a higher frequency of lightning strikes is associated with slower growth in labor productivity across the 48 contiguous US states after 1990; before 1990 there is no correlation between growth and lightning. Other climate variables (e.g., temperature, rainfall and tornadoes) do not conform to this pattern. A viable explanation is that lightning influences IT diffusion. By causing voltage spikes and dips, a higher frequency of ground strikes leads to damaged digital equipment and thus higher IT user costs. Accordingly, the flash density (strikes per square km per year) should adversely affect the speed of IT diffusion. We find that lightning indeed seems to have slowed IT diffusion, conditional on standard controls. Hence, an increasing macroeconomic sensitivity to lightning may be due to the increasing importance of digital technologies for the growth process.

Fiber-pigtailed temperature sensors based on dielectric-loaded plasmonic waveguide-ring resonators

We demonstrate optical fiber-pigtailed temperature sensors based on dielectric-loaded surface plasmon-polariton waveguide-ring resonators (DLSPP-WRRs), whose transmission depends on the ambient temperature. The DLSPP-WRR-based temperature sensors represent polymer ridge waveguides (~1×1 µm(2) in cross section) forming 5-µm-radius rings coupled to straight waveguides fabricated by UV-lithography on a 50-nm-thick gold layer atop a 2.3-µm-thick CYTOP layer covering a Si wafer. A broadband light source is used to characterize the DLSPP-WRR wavelength-dependent transmission in the range of 1480-1600 nm and to select the DLSPP-WRR component for temperature sensing. In- and out-coupling single-mode optical fibers are then glued to the corresponding access (photonic) waveguides made of 10-µm-wide polymer ridges. The sample is heated from 21°C to 46 °C resulting in the transmission change of ~0.7 dB at the operation wavelength of ~1510 nm. The minimum detectable temperature change is estimated to be ~5.1∙10(-3) °C for the bandwidth of 1 Hz when using standard commercial optical detectors.

Is Africa's Recent Growth Sustainable?

Abstract In this paper we argue that the answer, to the question of whether Africas recent growth is sustainable, is yes. Our optimism rests on the finding that differences in the level of institutional quality predict cross-country variation in African economic growth during the period 1995–2011. This finding is quite robust. It holds in OLS, LAD and 2SLS settings; it holds for different measures of institutions and different measures of economic growth; and it holds for the period before and the period after the global financial crisis. We also show that changes in institutional quality predict cross-country variation in African economic growth. Moreover, if we split our sample into two equally sized groups, a high-growth and a low-growth group, then the high-growth group has experienced a statistically significant increase in institutional quality, whereas the low-growth group has not. Overall, this makes it probable that institutions have played an important part in Africas recent growth acceleration. The continent has seen many false dawns, caused in large part by increases in commodity prices, but a growth acceleration driven by institutions is likely to signify a genuine African takeoff.