Negative Differential Resistance in the Scanning Tunneling Spectroscopy of Organic molecules

The conductance-voltage spectrum of molecular nanostructures measured by scanning tunneling spectroscopy (STS) is generally assumed to reflect the local density of states of the molecule. This excludes the possibility of observing negative differential resistance (NDR). We report here the observation of NDR in the scanning tunneling microscope (STM) current-voltage (I-V) characteristics of self-assembled monolayer (SAM) of 4-p-Terphenylthiol molecules on gold substrate measured using a platinum probe. We argue that the NDR arises from narrow structures in the local density of states at the tip apex atom and show that depending on the electrostatic potential profile across the system, NDR could be observed in one or both bias directions.Comment: 13 Pages, 4 figures, submitted to Phys. Rev. B Rapid Communicatio

Synthesis of neutral nickel catalysts for ethylene polymerization – the influence of ligand size on catalyst stability

A facile synthesis of nickel salicylaldimine complexes with labile dissociating ligands is described. In addition to producing highly active ethylene polymerization catalysts, important insights into the effect of ligand size on catalyst stability and information on the mechanism of polymerization are provided

Governmental influences on drug development: striking a better balance

The article of record as published may be found at https://doi.org/0.1038/nrd2323There is currently considerable debate in many countries over the effects of public policy — in particular, governmental regulation — on the development of innovative pharmaceuticals. Regulators must balance patients’ access to therapies with ensuring the safety of drugs. The consequences of poor decisions can be dire: if access is promoted at the expense of safety, a dangerous product can cause incalculable harm; conversely, if safety is over-emphasized at the expense of access, patients can suffer from the absence of life-saving and life- enhancing medications. Using the United States as an example, we discuss the influence of governmental bodies such as the US Food and Drug Administration (FDA), as well as recent legislative initiatives, on pharmaceutical innovation. We argue for a balanced approach to governmental interventions

An Extension of the Compression-Expansion Fixed Point Theorem of Functional Type

In this article we use an interval of functional type as the underlying set in our compression-expansion fixed point theorem argument which can be used to exploit properties of the operator to improve conditions that will guarantee the existence of a fixed point in applications. An example is provided to demonstrate how intervals of functional type can improve conditions in applications to boundary value problems. We also show how one can use suitable k-contractive conditions to prove that a fixed point in a functionaltype interval is unique

Effects of ignoring inbreeding in model-based accuracy for BLUP and SSGBLUP

[EN] Model-based accuracy, defined as the theoretical correlation between true and estimated breeding value, can be obtained for each individual as a function of its prediction error variance (PEV) and inbreeding coefficient F, in BLUP, GBLUP and SSGBLUP genetic evaluations. However, for computational convenience, inbreeding is often ignored in two places. First, in the computation of reliability = 1-PEV/(1 + F). Second, in the set-up, using Henderson's rules, of the inverse of the pedigree-based relationship matrix A. Both approximations have an effect in the computation of model-based accuracy and result in wrong values. In this work, first we present a reminder of the theory and extend it to SSGBLUP. Second, we quantify the error of ignoring inbreeding with real data in three scenarios: BLUP evaluation and SSGBLUP in Uruguayan dairy cattle, and BLUP evaluations in a line of rabbit closed for >40 generations with steady increase of inbreeding up to an average of 0.30. We show that ignoring inbreeding in the set-up of the A-inverse is equivalent to assume that non-inbred animals are actually inbred. This results in an increase of apparent PEV that is negligible for dairy cattle but considerable for rabbit. Ignoring inbreeding in reliability = 1-PEV/(1 + F) leads to underestimation of reliability for BLUP evaluations, and this underestimation is very large for rabbit. For SSGBLUP in dairy cattle, it leads to both underestimation and overestimation of reliability, both for genotyped and non-genotyped animals. We strongly recommend to include inbreeding both in the set-up of A-inverse and in the computation of reliability from PEVs.FEDER; INRA; Universidad Nacional de Lomas de Zamora; European Unions' Horizon 2020 Research & Innovation Programme, Grant/Award Number: No772787Aguilar, I.; Fernandez, EN.; Blasco Mateu, A.; Ravagnolo, O.; Legarra, A. (2020). Effects of ignoring inbreeding in model-based accuracy for BLUP and SSGBLUP. Journal of Animal Breeding and Genetics. 137(4):356-364. https://doi.org/10.1111/jbg.12470S3563641374Bijma, P. (2012). Accuracies of estimated breeding values from ordinary genetic evaluations do not reflect the correlation between true and estimated breeding values in selected populations. Journal of Animal Breeding and Genetics, 129(5), 345-358. doi:10.1111/j.1439-0388.2012.00991.xChristensen, O. F., Madsen, P., Nielsen, B., Ostersen, T., & Su, G. (2012). Single-step methods for genomic evaluation in pigs. Animal, 6(10), 1565-1571. doi:10.1017/s1751731112000742Colleau, J.-J., Palhière, I., Rodríguez-Ramilo, S. T., & Legarra, A. (2017). A fast indirect method to compute functions of genomic relationships concerning genotyped and ungenotyped individuals, for diversity management. Genetics Selection Evolution, 49(1). doi:10.1186/s12711-017-0363-9Edel, C., Pimentel, E. C. G., Erbe, M., Emmerling, R., & Götz, K.-U. (2019). Short communication: Calculating analytical reliabilities for single-step predictions. Journal of Dairy Science, 102(4), 3259-3265. doi:10.3168/jds.2018-15707Fernández, E. N., Sánchez, J. P., Martínez, R., Legarra, A., & Baselga, M. (2017). Role of inbreeding depression, non-inbred dominance deviations and random year-season effect in genetic trends for prolificacy in closed rabbit lines. Journal of Animal Breeding and Genetics, 134(6), 441-452. doi:10.1111/jbg.12284Golden, B. L., Brinks, J. S., & Bourdon, R. M. (1991). A performance programmed method for computing inbreeding coefficients from large data sets for use in mixed-model analyses. Journal of Animal Science, 69(9), 3564-3573. doi:10.2527/1991.6993564xGroeneveld E. Kovac M. &Wang T.(1990).PEST a general purpose BLUP package for multivariate prediction and estimation. Proceedings of the 4th World Congress on Genetics Applied to Livestock Production Edinburgh 13 488–491.Henderson, C. R. (1975). Best Linear Unbiased Estimation and Prediction under a Selection Model. Biometrics, 31(2), 423. doi:10.2307/2529430Henderson, C. R. (1976). A Simple Method for Computing the Inverse of a Numerator Relationship Matrix Used in Prediction of Breeding Values. Biometrics, 32(1), 69. doi:10.2307/2529339Legarra, A., Aguilar, I., & Colleau, J. J. (2020). Short communication: Methods to compute genomic inbreeding for ungenotyped individuals. Journal of Dairy Science, 103(4), 3363-3367. doi:10.3168/jds.2019-17750Legarra, A., Aguilar, I., & Misztal, I. (2009). A relationship matrix including full pedigree and genomic information. Journal of Dairy Science, 92(9), 4656-4663. doi:10.3168/jds.2009-2061Legarra A. Lourenco D. A. L. &Vitezica Z. G.(2018).Bases for genomic prediction. Retrieved fromhttp://genoweb.toulouse.inra.fr/~alegarra/Masuda, Y., Aguilar, I., Tsuruta, S., & Misztal, I. (2015). Technical note: Acceleration of sparse operations for average-information REML analyses with supernodal methods and sparse-storage refinements1,2. Journal of Animal Science, 93(10), 4670-4674. doi:10.2527/jas.2015-9395Matilainen, K., Strandén, I., Aamand, G. P., & Mäntysaari, E. A. (2018). Single step genomic evaluation for female fertility in Nordic Red dairy cattle. Journal of Animal Breeding and Genetics, 135(5), 337-348. doi:10.1111/jbg.12353Mehrabani-Yeganeh, H., Gibson, J. P., & Schaeffer, L. R. (2000). Including coefficients of inbreeding in BLUP evaluation and its effect on response to selection. Journal of Animal Breeding and Genetics, 117(3), 145-151. doi:10.1046/j.1439-0388.2000.00241.xMeyer, K. (2007). WOMBAT—A tool for mixed model analyses in quantitative genetics by restricted maximum likelihood (REML). Journal of Zhejiang University SCIENCE B, 8(11), 815-821. doi:10.1631/jzus.2007.b0815Misztal, I., & Wiggans, G. R. (1988). Approximation of Prediction Error Variance in Large-Scale Animal Models. Journal of Dairy Science, 71, 27-32. doi:10.1016/s0022-0302(88)79976-2Mrode, R. A., & Thompson, R. (Eds.). (2005). Linear models for the prediction of animal breeding values. doi:10.1079/9780851990002.0000Pryce, J. E., Gonzalez-Recio, O., Nieuwhof, G., Wales, W. J., Coffey, M. P., Hayes, B. J., & Goddard, M. E. (2015). Hot topic: Definition and implementation of a breeding value for feed efficiency in dairy cows. Journal of Dairy Science, 98(10), 7340-7350. doi:10.3168/jds.2015-9621Sargolzaei, M., Chesnais, J. P., & Schenkel, F. S. (2014). A new approach for efficient genotype imputation using information from relatives. BMC Genomics, 15(1), 478. doi:10.1186/1471-2164-15-478Strandén, I., Matilainen, K., Aamand, G. P., & Mäntysaari, E. A. (2017). Solving efficiently large single-step genomic best linear unbiased prediction models. Journal of Animal Breeding and Genetics, 134(3), 264-274. doi:10.1111/jbg.12257Ten Napel J. Vandenplas J. Lidauer M. Stranden I. Taskinen M. Mäntysaari E. Veerkamp R. F.(2017).MiXBLUP user‐friendly software for large genetic evaluation systems–Manual V2. Retrived from:https://www.mixblup.eu/documents/Manual%20MiXBLUP%202.1_June%202017_V2.pdfTier B. Schneeberger M. Hammond K. &Fuchs W. C.(1991).Determining the accuracy of estimated breeding values in multiple trait animal models. Proceedings of the 9th AAABG Conference 239–242Van Vleck, L. D. (1993). Variance of prediction error with mixed model equations when relationships are ignored. Theoretical and Applied Genetics, 85(5), 545-549. doi:10.1007/bf00220912VanRaden, P. M. (2008). Efficient Methods to Compute Genomic Predictions. Journal of Dairy Science, 91(11), 4414-4423. doi:10.3168/jds.2007-0980Xiang, T., Christensen, O. F., & Legarra, A. (2017). Technical note: Genomic evaluation for crossbred performance in a single-step approach with metafounders1. Journal of Animal Science, 95(4), 1472-1480. doi:10.2527/jas.2016.115

Phase behavior of a confined nano-droplet in the grand-canonical ensemble: the reverse liquid-vapor transition

The equilibrium density distribution and thermodynamic properties of a Lennard-Jones fluid confined to nano-sized spherical cavities at constant chemical potential was determined using Monte Carlo simulations. The results describe both a single cavity with semipermeable walls as well as a collection of closed cavities formed at constant chemical potential. The results are compared to calculations using classical Density Functional Theory (DFT). It is found that the DFT calculations give a quantitatively accurate description of the pressure and structure of the fluid. Both theory and simulation show the presence of a ``reverse'' liquid-vapor transition whereby the equilibrium state is a liquid at large volumes but becomes a vapor at small volumes.Comment: 13 pages, 8 figures, to appear in J. Phys. : Cond. Mat

Formation and control of nitrogenous DBPs from Western Australian source waters: Investigating the impacts of high nitrogen and bromide concentrations

We studied the formation of four nitrogenous DBPs (N-DBPs) classes (haloacetonitriles, halonitromethanes, haloacetamides, and N-nitrosamines), as well as trihalomethanes and total organic halogen (TOX), after chlorination or chloramination of source waters. We also evaluated the relative and additive toxicity of N-DBPs and water treatment options for minimisation of N-DBPs. The formation of halonitromethanes, haloacetamides, and N-nitrosamines was higher after chloramination and positively correlated with dissolved organic nitrogen or total nitrogen. N-DBPs were major contributors to the toxicity of both chlorinated and chloraminated waters. The strong correlation between bromide concentration and the overall calculated DBP additive toxicity for both chlorinated and chloraminated source waters demonstrated that formation of brominated haloacetonitriles was the main contributor to toxicity. Ozone–biological activated carbon treatment was not effective in removing N-DBP precursors. The occurrence and formation of N-DBPs should be investigated on a case-by-case basis, especially where advanced water treatment processes are being considered to minimise their formation in drinking waters, and where chloramination is used for final disinfection

High-precision measurement of the half-life of 62^{62}Ga

The beta-decay half-life of 62Ga has been studied with high precision using on-line mass separated samples. The decay of 62Ga which is dominated by a 0+ to 0+ transition to the ground state of 62Zn yields a half-life of T_{1/2} = 116.19(4) ms. This result is more precise than any previous measurement by about a factor of four or more. The present value is in agreement with older literature values, but slightly disagrees with a recent measurement. We determine an error weighted average value of all experimental half-lives of 116.18(4) ms.Comment: 9 pages, 5 figures, accepted for publication in PR

Fusion-Fission of 16O+197Au at Sub-Barrier Energies

The recent discovery of heavy-ion fusion hindrance at far sub-barrier energies has focused much attention on both experimental and theoretical studies of this phenomenon. Most of the experimental evidence comes from medium-heavy systems such as Ni+Ni to Zr+Zr, for which the compound system decays primarily by charged-particle evaporation. In order to study heavier systems, it is, however, necessary to measure also the fraction of the decay that goes into fission fragments. In the present work we have, therefore, measured the fission cross section of 16O+197Au down to unprecedented far sub-barrier energies using a large position sensitive PPAC placed at backward angles. The preliminary cross sections will be discussed and compared to earlier studies at near-barrier energies. No conclusive evidence for sub-barrier hindrance was found, probably because the measurements were not extended to sufficiently low energies.Comment: Fusion06 - Intl. Conf. on Reaction Mechanisms and Nuclear Structure at the Coulomb Barrier, San Servolo, Venezia, Italy, March 19-223, 2006 5 pages, 4 figure

Multi-confocal fluorescence correlation spectroscopy in living cells using a complementary metal oxide semiconductor-single photon avalanche diode array

International audienceLiving cells are heterogeneous and rapidly changing biological samples. It is thus desirable to measure molecular concentration and dynamics in many locations at the same time. In this note, we present a multi-confocal setup capable of performing simultaneous fluorescence correlation spectroscopy measurements, by focusing the spots with a spatial light modulator and acquiring data with a monolithic 32 × 32 single-photon avalanche photodiode array. A post-processing method is proposed to correct cross-talk effects between neighboring spots. We demonstrate the applicability of our system by simultaneously measuring the diffusion of free enhanced Green Fluorescent Protein (eGFP) molecules at nine different points in living cells