Knowledge Structures.

This paper investigates how technological distance between firms affects their network of R&D alliances. Our theoretic model assumes that the benefit of an alliance between two firms is given by their technological distance. This benefit-distance relationship determines the ego-network of each firm as well as the overall network structure. Empirical relevance is confirmed for the bio-pharmaceutical industry. Although we find that the network structure is largely explained by firm size, technological distance determines the positioning of firms in the network.technological distance, research alliance, network formation, pharmaceutical industry.

Detection of a branched alkyl molecule in the interstellar medium: iso-propyl cyanide

The largest non-cyclic molecules detected in the interstellar medium (ISM) are organic with a straight-chain carbon backbone. We report an interstellar detection of a branched alkyl molecule, iso-propyl cyanide (i-C3H7CN), with an abundance 0.4 times that of its straight-chain structural isomer. This detection suggests that branched carbon-chain molecules may be generally abundant in the ISM. Our astrochemical model indicates that both isomers are produced within or upon dust grain ice mantles through the addition of molecular radicals, albeit via differing reaction pathways. The production of iso-propyl cyanide appears to require the addition of a functional group to a non-terminal carbon in the chain. Its detection therefore bodes well for the presence in the ISM of amino acids, for which such side-chain structure is a key characteristic.Comment: This is the author's version of the work. It is posted here by permission of the AAAS for non-commercial use. The definitive version was published in Science 345, 1584 (2014), doi:10.1126/science.125667

On the value of foreign PhDs in the developing world: Training versus selection effects

This paper compares the career effects of overseas and domestic PhD training for scientists working in an emerging economy, South Africa. Variations in scientific achievements of South African academics may arise because those who attend \better" PhD programmes receive better training, but it may also be because good students select into good universities. We examine selection and training effects for four tiers of South African and two tiers of foreign universities. Those who received PhDs from universities in industrialized countries tend to be more productive than those whose PhDs were locally granted, but universities from industrialized countries do not necessarily provide better training than local universities. Pure selection effects contribute to career outcomes nearly as much as training effects. When looking at training in isolation, PhDs from top South African universities produce a similar quantity and quality research output to those from leading universities in the developed world

DETERMINATION OF OPTIMAL FILTER PARAMETERS FOR FILTERING KINEMATIC WALKING DATA USING BUTTERWORTH LOW PASS FILTER

INTRODUCTION: Noise in biomechanical displacement data are often reduced by digital filter routines. In literature the cross-validated quintic spline from Woltring (1986) and the Butterworth low pass filter are commonly used. Challis (1999) recently suggested a method for determining the optimal cut-off frequency of Butterworth low pass filters. This method is based on a combination of residual analysis and autocorrelation. The optimization of the filter order, however, is not discussed by Challis. Thus the purpose of this study was to determine optimal filter parameters (frequency and order) of a Butterworth low-pass filter using the approach of Challis applied to a kinematic data set in walking

CHANGE OF KINETIC LOWER EXTREMITY JOINT VARIABLES DURING UP- AND DOWNHILL WALKING ON DIFFERENTLY INCLINED SLOPES

INTRODUCTION: Lower extremity joint loads in level and downhill walking are reported in several papers (e.g. Kuster et al., 1995, Schwameder et al., 2000). The change of load distribution, however, between the ankle-, knee- and hip joint depending on slope inclination in up- and downhill walking are still not sufficiently presented. Thus the purpose of this study was to determine kinetic variables at the three main lower extremity joints as a function of both, declination and inclination of the slope

Area Efficient Modular Reduction in Hardware for Arbitrary Static Moduli

Modular reduction is a crucial operation in many post-quantum cryptographic schemes, including the Kyber key exchange method or Dilithium signature scheme. However, it can be computationally expensive and pose a performance bottleneck in hardware implementations. To address this issue, we propose a novel approach for computing modular reduction efficiently in hardware for arbitrary static moduli. Unlike other commonly used methods such as Barrett or Montgomery reduction, the method does not require any multiplications. It is not dependent on properties of any particular choice of modulus for good performance and low area consumption. Its major strength lies in its low area consumption, which was reduced by 60% for optimized and up to 90% for generic Barrett implementations for Kyber and Dilithium. Additionally, it is well suited for parallelization and pipelining and scales linearly in hardware resource consumption with increasing operation width. All operations can be performed in the bit-width of the modulus, rather than the size of the number being reduced. This shortens carry chains and allows for faster clocking. Moreover, our method can be executed in constant time, which is essential for cryptography applications where timing attacks can be used to obtain information about the secret key.Comment: 7 pages, 2 figure

Oligodendroglial Argonaute protein Ago2 associates with molecules of the Mbp mRNA localization machinery and is a downstream target of Fyn kinase

Oligodendrocytes myelinate neuronal axons in the central nervous system (CNS) facilitating rapid transmission of action potentials by saltatory conduction. Myelin basic protein (MBP) is an essential component of myelin and its absence results in severe hypomyelination in the CNS of rodents. Mbp mRNA is not translated immediately after exit from the nucleus in the cytoplasm, but is transported to the plasma membrane in RNA transport granules in a translationally silenced state. We have previously identified the small non-coding RNA 715 (sncRNA715) as an inhibitor of Mbp translation associated with RNA granules. Argonaute (Ago) proteins and small RNAs form the minimal core of the RNA induced silencing complex and together recognize target mRNAs to be translationally inhibited or degraded. Recently, tyrosine phosphorylation of Ago2 was reported to be a regulator of small RNA binding. The oligodendroglial non-receptor tyrosine kinase Fyn is activated by neuronal signals and stimulates the translation of Mbp mRNA at the axon-glial contact site. Here we analyzed the expression of Ago proteins in oligodendrocytes, if they associate with Mbp mRNA transport granules and are tyrosine phosphorylated by Fyn. We show that all Ago proteins (Ago1-4) are expressed by oligodendrocytes and that Ago2 colocalizes with hnRNP A2 in granular cytoplasmic structures. Ago2 associates with hnRNP A2, Mbp mRNA, sncRNA715 and Fyn kinase and is tyrosine phosphorylated in response to Fyn activity. Our findings suggest an involvement of Ago2 in the translational regulation of Mbp. The identification of Ago proteins as Fyn targets will foster further research to understand in more molecular detail how Fyn activity regulates Mbp translation