Measuring the impact of ride-hailing firms on urban congestion: The case of Uber in Europe

This paper examines the impact of Uber, the world's largest ride-hailing firm, on congestion. Drawing on data from European cities for the period 2008 through 2016, I find a negative impact of Uber on congestion. The estimated impact in the baseline regression is −3.5 percentage points, but it is higher in cities that do not impose strong regulatory restrictions to ride-hailing services. In addition, the negative impact of Uber on congestion is only statistically significant in denser cities. The Uber effect is gradual given that its impact increases over time. Finally, I find suggestive evidence that the potential endogeneity bias underestimates the negative effect of Uber on congestion.     

Identification of a New QTL Region on Mouse Chromosome 1 Responsible for Male Hypofertility: Phenotype Characterization and Candidate Genes

Male fertility disorders often have their origin in disturbed spermatogenesis, which can be induced by genetic factors. In this study, we used interspecific recombinant congenic mouse strains (IRCS) to identify genes responsible for male infertility. Using ultrasonography, in vivo and in vitro fertilization (IVF) and electron microscopy, the phenotyping of several IRCS carrying mouse chromosome 1 segments of Mus spretus origin revealed a decrease in the ability of sperm to fertilize. This teratozoospermia included the abnormal anchoring of the acrosome to the nucleus and a persistence of residual bodies at the level of epididymal sperm midpiece. We identified a quantitative trait locus (QTL) responsible for these phenotypes and we have proposed a short list of candidate genes specifically expressed in spermatids. The future functional validation of candidate genes should allow the identification of new genes and mechanisms involved in male infertility.     

Sources of parasitic features in the visible range of oxide transparent ceramics absorption spectra

This research focused on the identification of parasitic signal sources introduced by sintering under reductive atmospheres of oxide transparent ceramics. The examination encompassed a wide set of materials, like Mg-spinel, magnesia, alumina. YAG, yttria, zirconia and titania, so as to allow one to detect general rules if operating. The main finding is the dependence between the ability of such ceramics to generate, under reductive conditions, intrinsic parasitic light-absorbing centers and their composition and structure. Thus it was determined that oxides based on transition element cations have ,in this sense, abilities not present in the case of oxides of elements from the main periodic table groups. The reason is the possibility of non-absorbing transition cations to be reduced to oxidation states that absorb light. Drive toward reduced oxidation states is motivated by the stabilization energy associated with the ligand fields acting upon the such cations. It has been also found out that YAG lattice distortion, by dopants like tetravalent silicon or zirconium facilitates reduction of Y ³⁺ to Y ^{2 +} (a light absorbing, d¹, cation). Oxygen vacancies do not significantly influence visible light absorption. Carbon atoms penetrate inside ceramics, even dense ones and cause achromatic tints formation.     

Two New Fatty Acid Derivatives from the Stem Bark of <Emphasis Type="Italic">Alchornea laxiflora</Emphasis> (Euphorbiaceae)

Euphorbiaceae is a family of plants used in traditional remedies in central Africa to treat selected diseases. Some of the phytochemical components in the stem bark of Alchornea laxiflora that have biochemical activity were identified. A number of novel compounds were isolated, including a new fatty acid ester, (1) a new ceramide, (2) some triterpenoids, (3–5), ellagic acid (6) and its derivatives (7, 8) were isolated. The structures of these compounds were determined on the basis of spectroscopic methods as well as HR-ESI-TOF-MS analysis, chemical transformation and by comparison of their physical and spectral data with those reported in the literature. The cytotoxicity of some isolated compounds was investigated against human promyelocytic leukaemia (HL60) cell line by using the MTT method. Compounds 1, 4 and 5 showed a cytotoxic activity with IC₅₀ at 58.7, 6.6 and 6.8 μM, respectively.     

Silicon‐Based Laser Desorption Ionization Mass Spectrometry for the Analysis of Biomolecules: A Progress Report

Matrix‐assisted laser desorption/ionization mass spectrometry (MALDI‐MS) is widely used in the biomedical field for the label‐free analysis of molecules such as drugs, lipids, peptides, proteins, and biological tissues for molecular imaging. However, organic matrices used in traditional MALDI‐MS applications introduce excessive interferences in the low m/z range. For this reason, nanostructured materials—and in particular silicon‐based LDI strategies—have become a promising alternative, since they provide a much weaker background. Herein, the recent developments in fabrication, functionalization, and practical applications of silicon‐based LDI‐MS methods are reviewed. Also the basic requirements of silicon‐based substrates for optimal LDI analysis by providing an overview of the LDI mechanisms that use silicon‐based substrates instead of organic matrices are reported. Finally, the considerable potential of silicon‐based substrates is discussed, giving suggestions for topics for future research.     

Moral particularism in the light of deontic logic

The aim of this paper is to strengthen the point made by Horty about the relationship between reason holism and moral particularism. In the literature prima facie obligations have been considered as the only source of reason holism. I strengthen Horty??s point in two ways. First, I show that contrary-to-duties provide another independent support for reason holism. Next I outline a formal theory that is able to capture these two sources of holism. While in simple settings the proposed account coincides with Horty??s one, this is not true in more complicated or ??realistic?? settings in which more than two norms collide. My chosen formalism is so-called input/output logic. A bottom-line example is introduced. It raises the issue of whether the conventional wisdom is right in assuming that normative reasons run parallel to epistemic ones.     

Liquid zinc embrittlement of twinning-induced plasticity steel

The susceptibility of a Fe22Mn0.6C twinning-induced plasticity steel to liquid zinc embrittlement has been investigated by performing hot tensile tests on bare and electrogalvanized specimens using a Gleeble thermomechanical simulator. Tensile tests were carried out at different temperatures and strain rates. The studied steel can be severely embrittled by liquid zinc (drastic reductions in elongation at rupture and fracture strength) given particular conditions of temperature and strain rate.     

Theoretical and experimental studies of (In,Ga)As/GaP quantum dots

(In,Ga)As/GaP(001) quantum dots (QDs) are grown by molecular beam epitaxy and studied both theoretically and experimentally. The electronic band structure is simulated using a combination of k·p and tight-binding models. These calculations predict an indirect to direct crossover with the In content and the size of the QDs. The optical properties are then studied in a low-In-content range through photoluminescence and time-resolved photoluminescence experiments. It suggests the proximity of two optical transitions of indirect and direct types.