Closure in inter-regional knowledge networks: An application to the European co-publication network

The question of the determinants of inter-regional knowledge flows has received a growing interest in the recent past. Particularly, the question of the relationship between geography and networks has been debated. Yet, at the inter-regional level, there is no study assessing the effect of networks on the the value of knowledge flows. This may come from the fact that methodological tools assessing network characteristics at the dyadic level are lacking for aggregated networks (such as the network of inter-regional knowledge flows). This paper aims to fill this gap and contribute to the debate on the determinants of knowledge flows. To do so we first define a new measure to assess 'network proximity' at the level of the regional dyad, based on the concept of inter-regional bridging path. Here a bridging path is a path at the micro-level between two regions via a third one. For instance, if an agent from region B has collaborated with an agent from region A and an agent from region C, then there is a bridging path between A and C via B. By using the information at the aggregated level, and assuming a 'random matching process' of the agents at the micro level, we are able to derive a closed form of the total expected number of bridging paths between two given regions. By the concept of triadic closure at the micro-level, the regional pairs having a high number of bridging paths should be more prone to collaborate. We then illustrate the measure theoretically defined by making use of co-publications data from chemistry journals for the period 2001-2005, within the five largest European countries (France, Germany, Italy, Spain, the United Kingdom). The studied network is then composed of all the regional pairs among 386 active NUTS3 regions. Using a zero-inflated negative binomial regression model along gravity equations, we then assess the effect of geographical distance, spatial contiguity and national borders. We also assess the effect of 'network proximity' by using the expected number of bridging paths as a proxy. As in previous studies, the effects of the geographical distance or the national borders are negative. But we show that the measure of 'network proximity' has a positive and significant effect. All the more, it also significantly alleviates the impeding effect of national borders on cross-countries collaborations, then suggesting that 'network proximity' is a channel favored for international collaborations

High-impedence NbSi TES sensors for studying the cosmic microwave background radiation

Precise measurements of the cosmic microwave background (CMB) are crucial in cosmology, because any proposed model of the universe must account for the features of this radiation. Of all CMB measurements that the scientific community has not yet been able to perform, the CMB B-mode polarization is probably the most challenging from the instrumental point of view. The signature of primordial gravitational waves, which give rise to a B-type polarization, is one of the goals in cosmology today and amongst the first objectives in the field. For this purpose, high-performance low-temperature bolometric cameras, made of thousands of pixels, are currently being developed by many groups, which will improve the sensitivity to B-mode CMB polarization by one or two orders of magnitude compared to the Planck satellite HFI detectors. We present here a new bolometer structure that is able to increase the pixel sensitivities and to simplify the fabrication procedure. This innovative device replaces delicate membrane-based structures and eliminates the mediation of phonons: the incoming energy is directly captured and measured in the electron bath of an appropriate sensor and the thermal decoupling is achieved via the intrinsic electron-phonon decoupling of the sensor at very low temperature. Reported results come from a 204-pixel array of Nb$_{x}$Si$_{1-x}$ transition edge sensors with a meander structure fabricated on a 2-inch silicon wafer using electron-beam co-evaporation and a cleanroom lithography process. To validate the application of this device to CMB measurements, we have performed an optical calibration of our sample in the focal plane of a dilution cryostat test bench. We have demonstrated a light absorption close to 20% and an NEP of about 7$\times10^{-16}$ W/$\sqrt{Hz}$, which is highly encouraging given the scope for improvement in this type of detectors.Comment: 6 pages, 10 figures. arXiv admin note: text overlap with arXiv:1005.0555 by other author

How Patent Rights Affect University Science

How do intellectual property rights influence academic science? We investigate the consequences of the introduction of software patents in the U.S. on the publications of university researchers in the field of computer science. Difference-in-difference estimations reveal that software scientists at U.S. universities produced fewer publications (both in terms of quantity and quality) than their European counterparts after patent rights for software inventions were introduced. We then introduce a theoretical model that accounts for substitution and complementarity between patenting and publishing as well as for the direction of research. In line with the model’s prediction, further results show that the decrease in publications is largest for scientists at the bottom of the ability distribution. Further, we evidence a change in the direction of research following the reform towards more applied research

How patent rights affect university science

How do intellectual property rights influence academic science? We investigate the consequences of the introduction of software patents in the U.S. on the publications of university researchers in the field of computer science. Difference-in-difference estimations reveal that software scientists at U.S. universities produced fewer publications (both in terms of quantity and quality) than their European counterparts after patent rights for software inventions were introduced. We then introduce a theoretical model that accounts for substitution and complementarity between patenting and publishing as well as for the direction of research. In line with the model’s prediction, further results show that the decrease in publications is largest for scientists at the bottom of the ability distribution. Further, we evidence a change in the direction of research following the reform towards more applied research

Tunable Superconducting Properties of a-NbSi Thin Films and Application to Detection in Astrophysics

We report on the superconducting properties of amorphous NbxSi1-x thin films. The normal-state resistance and critical temperatures can be separately adjusted to suit the desired application. Notably, the relatively low electron-phonon coupling of these films makes them good candidates for an "all electron bolometer" for Cosmological Microwave Background radiation detection. Moreover, this device can be made to suit both high and low impedance readouts

Abnormal P300 in people with high risk of developing psychosis

Background Individuals with an “at-risk mental state” (or “prodromal” symptoms) have a 20–40% chance of developing psychosis; however it is difficult to predict which of them will become ill on the basis of their clinical symptoms alone. We examined whether neurophysiological markers could help to identify those who are particularly vulnerable. Method 35 cases meeting PACE criteria for the at-risk mental state (ARMS) and 57 controls performed an auditory oddball task whilst their electroencephalogram was recorded. The latency and amplitude of the P300 and N100 waves were compared between groups using linear regression. Results The P300 amplitude was significantly reduced in the ARMS group [8.6 ± 6.4 microvolt] compared to controls [12.7 ± 5.8 microvolt] (p < 0.01). There were no group differences in P300 latency or in the amplitude and latency of the N100. Of the at-risk subjects that were followed up, seven (21%) developed psychosis. Conclusion Reduction in the amplitude of the P300 is associated with an increased vulnerability to psychosis. Neurophysiological and other biological markers may be of use to predict clinical outcomes in populations at high risk

Detection chain and electronic readout of the QUBIC instrument

The Q and U Bolometric Interferometer for Cosmology (QUBIC) Technical Demonstrator (TD) aiming to shows the feasibility of the combination of interferometry and bolometric detection. The electronic readout system is based on an array of 128 NbSi Transition Edge Sensors cooled at 350mK readout with 128 SQUIDs at 1K controlled and amplified by an Application Specific Integrated Circuit at 40K. This readout design allows a 128:1 Time Domain Multiplexing. We report the design and the performance of the detection chain in this paper. The technological demonstrator unwent a campaign of test in the lab. Evaluation of the QUBIC bolometers and readout electronics includes the measurement of I-V curves, time constant and the Noise Equivalent Power. Currently the mean Noise Equivalent Power is ~ 2 x 10⁻¹⁶ W/√Hz

Detection chain and electronic readout of the QUBIC instrument

The Q and U Bolometric Interferometer for Cosmology (QUBIC) Technical Demonstrator (TD) aiming to shows the feasibility of the combination of interferometry and bolometric detection. The electronic readout system is based on an array of 128 NbSi Transition Edge Sensors cooled at 350mK readout with 128 SQUIDs at 1K controlled and amplified by an Application Specific Integrated Circuit at 40K. This readout design allows a 128:1 Time Domain Multiplexing. We report the design and the performance of the detection chain in this paper. The technological demonstrator unwent a campaign of test in the lab. Evaluation of the QUBIC bolometers and readout electronics includes the measurement of I-V curves, time constant and the Noise Equivalent Power. Currently the mean Noise Equivalent Power is ~ 2 x 10⁻¹⁶ W/√Hz