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See detailDirect effect in Germany and France A constitutional comparison
Gerkrath, Jörg UL

in Prinssen, J.; Schrauwen, A. (Eds.) Direct effect : rethinking a classic of EC legal doctrine (2002)

Detailed reference viewed: 141 (2 UL)
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See detailDirect effects of nicotine on rabbit preimplantation embryos.
Balling, Rudi UL; Beier, H. M.

in Toxicology (1985), 34(4), 309-13

The effects of various concentrations of nicotine on the in vitro development of 1-cell rabbit preimplantation embryos and on the DNA-synthesis of 4-day-old rabbit blastocysts are investigated. Exposure ... [more ▼]

The effects of various concentrations of nicotine on the in vitro development of 1-cell rabbit preimplantation embryos and on the DNA-synthesis of 4-day-old rabbit blastocysts are investigated. Exposure of rabbit preimplantation embryos to concentrations of nicotine higher than 1 X 10(-3) M results in a marked decrease in the in vitro development and in DNA-synthesis. Concentrations of nicotine below 1 X 10(-3) M have no effect on these early embryos. It can be concluded that the concentrations of nicotine which exert a direct embryotoxic effect are higher than the concentrations that may be expected in the blood circulation of humans considered to be "normal smokers". [less ▲]

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See detailDirect electro-optical pumping for hybrid CdSe nanocrystal/III-nitride based nano-light-emitting diodes
Mikulics, Martin; Arango, Y.C.; Winden, Andreas et al

in Applied Physics Letters (2016), 108

We propose a device concept for a hybrid nanocrystal/III-nitride based nano-LED. Our approach is based on the direct electro-optical pumping of nanocrystals (secondary excitation) by electrically driven ... [more ▼]

We propose a device concept for a hybrid nanocrystal/III-nitride based nano-LED. Our approach is based on the direct electro-optical pumping of nanocrystals (secondary excitation) by electrically driven InGaN/GaN nano-LEDs as the primary excitation source. To this end, a universal hybrid optoelectronic platform was developed for a large range of optically active nano- and mesoscopic structures. The advantage of the approach is that the emission of the nanocrystals can be electrically induced without the need of contacting them. The proof of principal was demonstrated for the electro-optical pumping of CdSe nanocrystals. The nano-LEDs with a diameter of 100 nm exhibit a very low current of 8 nA at 5V bias which is several orders of magnitude smaller than for those conventionally used. The leakage currents in the device layout were typically in the range of 8 pA to 20 pA/cm2 at 5V bias. The photon-photon down conversion efficiency was determined to be 27%. Microphotoluminescence and microelectroluminescence characterization demonstrate the potential for future optoelectronics and highly secure “green” information technology applications. [less ▲]

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See detailDirect elicitation of template concentration from quantification cycle (Cq) distributions in digital PCR
Mojtahedi, Mitra; Fouquier d'Hérouël, Aymeric UL; Huang, Sui

in Nucleic Acids Research (2014), 42(16), 126

Digital PCR (dPCR) exploits limiting dilution of a template into an array of PCR reactions. From this array the number of reactions that contain at least one (as opposed to zero) initial template is ... [more ▼]

Digital PCR (dPCR) exploits limiting dilution of a template into an array of PCR reactions. From this array the number of reactions that contain at least one (as opposed to zero) initial template is determined, allowing inferring the original template concentration. Here we present a novel protocol to efficiently infer the concentration of a sample and its optimal dilution for dPCR from few targeted qPCR assays. By taking advantage of the real-time amplification feature of qPCR as opposed to relying on endpoint PCR assessment as in standard dPCR prior knowledge of template concentration is not necessary. This eliminates the need for serial dilutions in a separate titration and reduces the number of necessary reactions. We describe the theory underlying our approach and discuss experimental moments that contribute to uncertainty. We present data from a controlled experiment where the initial template concentration is known as proof of principle and apply our method on directly monitoring transcript level change during cell differentiation as well as gauging amplicon numbers in cDNA samples after pre-amplification. [less ▲]

Detailed reference viewed: 175 (22 UL)
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See detailDirect Evaluation of Defect Distributions From Admittance Spectroscopy
Weiss, Thomas UL; Redinger, Alex UL; Regesch, David UL et al

in IEEE JOURNAL OF PHOTOVOLTAICS (2014), 4

Detailed reference viewed: 195 (12 UL)
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See detailDirect evidence for cycloidal modulations in the thermal-fluctuation-stabilized spin spiral and skyrmion states of GaV 4 S 8
White, J. S.; Butykai, A.; Cubitt, R. et al

in Physical Review. B (2018), 97(2), 020401

We report small-angle neutron scattering studies of the lacunar spinelGaV4S8,which reveal the long-wavelength <br />magnetic phases to be cycloidally modulated. Upon cooling, these modulated phases ... [more ▼]

We report small-angle neutron scattering studies of the lacunar spinelGaV4S8,which reveal the long-wavelength <br />magnetic phases to be cycloidally modulated. Upon cooling, these modulated phases, including a recently <br />proposed Néel-type skyrmion phase, transform into a simple ferromagnetic state. These results indicate the <br />modulated phases in GaV4S8 gain their stability from thermal fluctuations, while at lower temperatures the <br />ferromagnetic state emerges in accord with the strong easy-axis magnetic anisotropy. Crucially, our study provides <br />microscopic evidence that the skyrmions in GaV4S8 indeed display a Néel-type helicity. More generally, our <br />approach can be applied to evidence the helicity of any bulk skyrmion phase. [less ▲]

Detailed reference viewed: 106 (5 UL)
See detailDirect gaze of female nudes influences startle in men
Lass-Hennemann, J.; Schulz, André UL; Nees, F. et al

in Herrmann, C. S.; Sabel, B. A. (Eds.) Tagungsband Psychologie und Gehirn 2008 (2008)

Detailed reference viewed: 74 (0 UL)
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See detailDirect gaze of photographs of female nudes influences startle in men
Lass-Hennemann, J.; Schulz, André UL; Nees, F. et al

in International Journal of Psychophysiology (2009), 72(2), 111-114

Detailed reference viewed: 136 (0 UL)
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See detailDirect gaze of photographs of female nudes influences startle in men
Lass-Hennemann, J.; Schulz, André UL; Nees, F. et al

in Abstracts - Society for Neuroscience (2008), 38

Detailed reference viewed: 130 (0 UL)
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See detailDirect image-analysis methods for surgical simulation and mixed meshfree methods
Hale, Jack UL; Bordas, Stéphane UL; Kerfriden, Pierre et al

Presentation (2014, May 28)

Detailed reference viewed: 134 (11 UL)
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See detailDirect observation of polar tweed in LaAlO3
Salje, Ekhard K. H.; Alexe, Marin; Kustov, Sergey et al

in SCIENTIFIC REPORTS (2016), 6

Polar tweed was discovered in mechanically stressed LaAlO3. Local patches of strained material (diameter ca. 5 mu m) form interwoven patterns seen in birefringence images, Piezo-Force Microscopy (PFM) and ... [more ▼]

Polar tweed was discovered in mechanically stressed LaAlO3. Local patches of strained material (diameter ca. 5 mu m) form interwoven patterns seen in birefringence images, Piezo-Force Microscopy (PFM) and Resonant Piezoelectric Spectroscopy (RPS). PFM and RPS observations prove unequivocally that electrical polarity exists inside the tweed patterns of LaAlO3. The local piezoelectric effect varies greatly within the tweed patterns and reaches magnitudes similar to quartz. The patterns were mapped by the shift of the E-g soft-mode frequency by Raman spectroscopy. [less ▲]

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See detailDirect reprogramming of fibroblasts into neural stem cells by defined factors.
Han, Dong Wook; Tapia, Natalia; Hermann, Andreas et al

in Cell Stem Cell (2012), 10(4), 465-72

Recent studies have shown that defined sets of transcription factors can directly reprogram differentiated somatic cells to a different differentiated cell type without passing through a pluripotent state ... [more ▼]

Recent studies have shown that defined sets of transcription factors can directly reprogram differentiated somatic cells to a different differentiated cell type without passing through a pluripotent state, but the restricted proliferative and lineage potential of the resulting cells limits the scope of their potential applications. Here we show that a combination of transcription factors (Brn4/Pou3f4, Sox2, Klf4, c-Myc, plus E47/Tcf3) induces mouse fibroblasts to directly acquire a neural stem cell identity-which we term as induced neural stem cells (iNSCs). Direct reprogramming of fibroblasts into iNSCs is a gradual process in which the donor transcriptional program is silenced over time. iNSCs exhibit cell morphology, gene expression, epigenetic features, differentiation potential, and self-renewing capacity, as well as in vitro and in vivo functionality similar to those of wild-type NSCs. We conclude that differentiated cells can be reprogrammed directly into specific somatic stem cell types by defined sets of specific transcription factors. [less ▲]

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See detailDirecting remittances to education with soft and hard commitments: Evidence from a lab-in-the-field experiment and new product take-up among Filipino migrants in Rome
Joxhe, Majlinda UL; De Arcangelis, Giuseppe; McKenzie, David et al

in Journal of Economic Behavior and Organization (2015), 111

This paper tests how migrants’ willingness to remit changes when given the ability to direct remittances to educational purposes using different forms of commitment. Variants of a dictator game in a lab ... [more ▼]

This paper tests how migrants’ willingness to remit changes when given the ability to direct remittances to educational purposes using different forms of commitment. Variants of a dictator game in a lab-in-the-field experiment with Filipino migrants in Rome are used to examine remitting behavior under varying degrees of commitment. These range from the soft commitment of simply labeling remittances as being for education, to the hard commitment of having funds directly paid to a school and the student’s educational performance monitored. We find that the introduction of simple labeling for education raises remittances by more than 15%. Adding the ability to directly send this funding to the school adds only a further 2.2%. We randomly vary the information asymmetry between migrants and their most closely connected household, but find no significant change in the remittance response to these forms of commitment as information varies. Behavior in these games is then shown to be predictive of take-up of a new financial product called EduPay, designed to allow migrants to directly pay remittances to schools in the Philippines. We find this take-up is largely driven by a response to the ability to label remittances for education, rather than to the hard commitment feature of directly paying schools. [less ▲]

Detailed reference viewed: 137 (13 UL)
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See detailDirection Estimation in Partially Unknown Noise Fields
Göransson, Bo; Ottersten, Björn UL

in IEEE Transactions on Signal Processing (1999), 47

Detailed reference viewed: 27 (0 UL)
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See detailDirection of Arrival Estimation and Localization Exploiting Sparse and One-Bit Sampling
Sedighi, Saeid UL

Doctoral thesis (2021)

Data acquisition is a necessary first step in digital signal processing applications such as radar, wireless communications and array processing. Traditionally, this process is performed by uniformly ... [more ▼]

Data acquisition is a necessary first step in digital signal processing applications such as radar, wireless communications and array processing. Traditionally, this process is performed by uniformly sampling signals at a frequency above the Nyquist rate and converting the resulting samples into digital numeric values through high-resolution amplitude quantization. While the traditional approach to data acquisition is straightforward and extremely well-proven, it may be either impractical or impossible in many modern applications due to the existing fundamental trade-off between sampling rate, amplitude quantization precision, implementation costs, and usage of physical resources, e.g. bandwidth and power consumption. Motivated by this fact, system designers have recently proposed exploiting sparse and few-bit quantized sampling instead of the traditional way of data acquisition in order to reduce implementation costs and usage of physical resources in such applications. However, before transition from the tradition data acquisition method to the sparsely sampled and few-bit quntized data acquisition approach, a study on the feasibility of retrieving information from sparsely sampled and few-bit quantized data is first required to be conducted. This study should specifically seek to find the answers to the following fundamental questions: 1-Is the problem of retrieving the information of interest from sparsely sampled and few-bit quantized data an identifiable problem? If so, what are the identifiability conditions? 2-Under the identifiability conditions: what are the fundamental performance bounds for the problem of retrieving the information of interest from sparsely sampled and few-bit quantized data? and how close are these performance bounds to those of retrieving the same information from the data acquired through the traditional approach? 3-Does there exist any computationally efficient algorithm for retrieving the information of interest from sparsely sampled and few-bit quantized data capable of achieving the corresponding performance bounds? My thesis focuses on finding the answers to the above fundamental questions for the problems of Direction of Arrival (DoA) estimation and localization, which are of the most important information retrieval problems in radar, wireless communication and array processing. Inthis regard, the first part of this thesis focuses on DoA estimation using Sparse Linear Arrays (SLAs). I consider this problem under three plausible scenarios from quantization perspective. Firstly, I assume that an SLA quantized the received signal to a large number of bits per samples such that the resulting quantization error can be neglected. Although the literature presents a variety of estimators under such circumstances, none of them are (asymptotically) statistically efficient. Motivated by this fact, I introduce a novel estimator for the DoA estimation from SLA data employing the Weighted Least Squares (WLS) method. I analytically show that the large sample performance of the proposed estimator coincides with the Cram\'{e}r-Rao Bound (CRB), thereby ensuring its asymptotic statistical efficiency. Next, I study the problem of DoA estimation from one-bit SLA measurements. The analytical performance of DoA estimation from one-bit SLA measurements has not yet been studied in the literature and performance analysis in the literature has be limited to simulations studies. Therefore, I study the performance limits of DoA estimation from one-bit SLA measurements through analyzing the identifiability conditions and the corresponding CRB. I also propose a new algorithm for estimating DoAs from one-bit quantized data. I investigate the analytical performance of the proposed method through deriving a closed-form expression for the covariance matrix of its asymptotic distribution and show that it outperforms the existing algorithms in the literature. Finally, the problem of DoA estimation from low-resolution multi-bit SLA measurements, e.g. $2$ or $4$ bit per sample, is studied. I develop a novel optimization-based framework for estimating DoAs from low-resolution multi-bit measurements. It is shown that increasing the sampling resolution to $2$ or $4$ bits per samples could significantly increase the DoA estimation performance compared to the one-bit sampling case while the power consumption and implementation costs are still much lower compared to the high-resolution sampling scenario. In the second part of the thesis, the problem of target localization is addressed. Firstly, I consider the problem of passive target localization from one-bit data in the context of Narrowband Internet-of-Things (NB-IoT). In the recently proposed narrowband IoT (NB-IoT) standard, which trades off bandwidth to gain wide area coverage, the location estimation is compounded by the low sampling rate receivers and limited-capacity links. I address both of these NB-IoT drawbacks by consider a limiting case where each node receiver employs one-bit analog-to-digital-converters and propose a novel low-complexity nodal delay estimation method. Then, to support the low-capacity links to the fusion center (FC), the range estimates obtained at individual sensors are converted to one-bit data. At the FC, I propose a novel algorithm for target localization with the aggregated one-bit range vector. My overall one-bit framework not only complements the low NB-IoT bandwidth but also supports the design goal of inexpensive NB-IoT location sensing. Secondly, in order to reduce bandwidth usage for performing high precision time of arrival-based localization, I developed a novel sparsity-aware target localization algorithm with application to automotive radars. The thesis concludes with summarizing the main research findings and some remarks on future directions and open problems. [less ▲]

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See detailDirection-of-Arrival Estimation for Wide-Band Signals Using the ESPRIT Algorithm
Ottersten, Björn UL; Kailath, T.

in IEEE Transactions on Acoustics, Speech, and Signal Processing (1990), ASSP-38(2), 317327

Detailed reference viewed: 36 (0 UL)
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See detailDirectional Dependence of Large Scale Parameters in Wireless Channel Models
Jalden, Niklas; Zetterberg, Per; Ottersten, Björn UL

in IEEE Wireless Communications (2008)

In this paper the autocorrelation properties of shadow fading and angle spread at both the base station (BS) and at the mobile station (MS) are analyzed using urban macro cellular measurement data. The ... [more ▼]

In this paper the autocorrelation properties of shadow fading and angle spread at both the base station (BS) and at the mobile station (MS) are analyzed using urban macro cellular measurement data. The shadow fading parameter is shown to have a longer decorrelation distance than the angle spread at both the BS and at the MS. Furthermore, we observe variations in the shadow fading that depend on the direction of the MS movement. The same dependence is not observed in the angle spreads. These results indicate that the origin of the angle spread is local to the transmitter and receiver, while the shadow fading depends on the intermediate environment. [less ▲]

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See detailDirectional Modulation via Symbol-Level Precoding: A Way to Enhance Security
Kalantari, Ashkan UL; Soltanalian, Mojtaba; Maleki, Sina UL et al

in IEEE Journal of Selected Topics in Signal Processing (2016)

Wireless communication provides a wide coverage at the cost of exposing information to unintended users. As an information-theoretic paradigm, secrecy rate derives bounds for secure transmission when the ... [more ▼]

Wireless communication provides a wide coverage at the cost of exposing information to unintended users. As an information-theoretic paradigm, secrecy rate derives bounds for secure transmission when the channel to the eavesdropper is known. However, such bounds are shown to be restrictive in practice and may require exploitation of specialized coding schemes. In this paper, we employ the concept of directional modulation and follow a signal processing approach to enhance the security of multi-user MIMO communication systems when a multi-antenna eavesdropper is present. Enhancing the security is accomplished by increasing the symbol error rate at the eavesdropper. Unlike the information-theoretic secrecy rate paradigm, we assume that the legitimate transmitter is not aware of its channel to the eavesdropper, which is a more realistic assumption. We examine the applicability of MIMO receiving algorithms at the eavesdropper. Using the channel knowledge and the intended symbols for the users, we design security enhancing symbol-level precoders for different transmitter and eavesdropper antenna configurations. We transform each design problem to a linearly constrained quadratic program and propose two solutions, namely the iterative algorithm and one based on non-negative least squares, at each scenario for a computationally-efficient modulation. Simulation results verify the analysis and show that the designed precoders outperform the benchmark scheme in terms of both power efficiency and security enhancement. [less ▲]

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See detailDirectional Plasmonic Excitation by Helical Nanotips
Singh, Leeju; Maccaferri, Nicolò UL; Garoli, Denis et al

in Nanomaterials (2021), 11(5), 1333

The phenomenon of coupling between light and surface plasmon polaritons requires specific momentum matching conditions. In the case of a single scattering object on a metallic surface, such as a ... [more ▼]

The phenomenon of coupling between light and surface plasmon polaritons requires specific momentum matching conditions. In the case of a single scattering object on a metallic surface, such as a nanoparticle or a nanohole, the coupling between a broadband effect, i.e., scattering, and a discrete one, such as surface plasmon excitation, leads to Fano-like resonance lineshapes. The necessary phase matching requirements can be used to engineer the light–plasmon coupling and to achieve a directional plasmonic excitation. Here, we investigate this effect by using a chiral nanotip to excite surface plasmons with a strong spin-dependent azimuthal variation. This effect can be described by a Fano-like interference with a complex coupling factor that can be modified thanks to a symmetry breaking of the nanostructure. [less ▲]

Detailed reference viewed: 34 (0 UL)