Evaluation of the risk of contamination by pesticides

Pesticides have the particularity of accumulating mainly in aquatic  ecosystems. The concentration of pesticides in such contaminated  ecosystems appears to be a potential health risk resulting from the human consumption of fish from these ecosystems. The aim of this study is to determine the pesticide residue levels of Chrysichthys nigrodigitatus and Tilapia zilli × Tilapia guinensis. 120 samples of each species, distributed from 96 samples for sector IV and 24 samples for sector V, were collected from February 2014 to January 2015. These were analyzed by gas chromatography coupled to a spectrometer of mass (GC / MS), after extraction and purification respectively by accelerated solvent extraction (ASE) and by adsorption chromatography on Oasis HLB Plus cartridges. Pesticide concentrations detected in fish muscle ranged from 0 to 40.66 ìg / kg in the study area. All values found for the health risk index (HI) in Chrysichthys nigrodigitatus and Tilapia hybrid muscles are well below 1 (HI < 1). Pesticide residues detected in both fish species do not pose a potential risk to human health.Keywords: Contamination, pesticides, Chrysichthys nigrodigitatus, Tilapia, risk. French Title: Evaluation du risque de contamination par les pesticidesLes pesticides ont la particularité de s’accumuler principalement dans les écosystèmes aquatiques. La concentration de pesticides dans de tels écosystèmes contaminés apparaît comme un risque potentiel pour la santé résultant de la consommation humaine de poissons de ces écosystèmes. Cette étude a pour objectif de déterminer la concentration de résidus de pesticides chez Chrysichthys nigrodigitatus et Tilapia zilli × Tilapia guinensis. 120 échantillons de chaque espèce, repartis en raison de 96 échantillons pour le secteur IV et 24 échantillons pour le secteur V, ont été collectés de février 2014 à janvier 2015. Ceux-ci ont été analysés par chromatographie en phase gazeuse couplée à un spectromètre de masse (GC / MS), après Extraction et purification respectivement par ExtractionAccélérée par Solvant (ASE) et par chromatographie d’adsorption sur cartouches Oasis HLB Plus. Les concentrations de pesticides quantifiés et non détectés dans les muscles des poissons variaient entre 0 et 40,66 ìg/kg dans la zone d’étude. Toutes les valeurs trouvées pour l’indice de risque pour la santé (HI) dans les muscles de Chrysichthys nigrodigitatus et de Tilapia hybride sont nettement inférieures à 1 (HI <1). Les résidus de pesticides détectés chez les deux espèces de poisson ne présentent pasde risque potentiel pour la santé humaine.Mots-clés : Contaminations, pesticides, Chrysichthys nigrodigitatus, Tilapia, risque

Malfunction of a ventriculoperitoneal shunt during pregnancy: Two clinical cases and literature review

Bringing a pregnancy to term is possible for a woman carrying a ventriculoperitoneal bypass valve, however, pregnancy can be a source of malfunction of the bypass system. We report two cases of malfunction of a VPS during the pregnancy's 3rd trimester in two patients aged 25 and 30 years respectively. The valve was examined in both cases and the persistence of the neurological signs required a cesarean section. The diagnostic aspects and management strategies were discussed as regards these two cases and throughout the literature review

The Non-Consensus 1992 Consensus

The 1992 Consensus is perhaps the most crucial political term for cross-strait relations. Surveys show that the public consistently supports it in Taiwan. Despite the alleged broad support, there has not been an academic study examining if Taiwanese people understand the content of the 1992 Consensus. Such an inquiry is important as the administration in Taiwan has yet accepted the Consensus in its interactions with Beijing. A nearly representative online survey was conducted in July 2018, and 1001 Taiwanese respondents were recruited to choose among different “definitions” of the 1992 Consensus. Results show that only one-third of the respondents chose the version that Kuomintang agreed on, while another one-third misperceived the 1992 Consensus as a country-to-country agreement. Taiwanese people might have supported the Consensus for content that it is not. We then discuss the policy implications of our study for both China and Taiwan and provide future research orientations

Signatures of black holes at the LHC

Signatures of black hole events at CERN's Large Hadron Collider are discussed. Event simulations are carried out with the Fortran Monte Carlo generator CATFISH. Inelasticity effects, exact field emissivities, color and charge conservation, corrections to semiclassical black hole evaporation, gravitational energy loss at formation and possibility of a black hole remnant are included in the analysis.Comment: 13 pages, 7 figure

Analysis of Various Polarization Asymmetries In The Inclusive b→sℓ+ℓ−b\to s \ell^+ \ell^- Decay In The Fourth-Generation Standard Model

In this study a systematical analysis of various polarization asymmetries in inclusive b \rar s \ell^+ \ell^- decay in the standard model (SM) with four generation of quarks is carried out. We found that the various asymmetries are sensitive to the new mixing and quark masses for both of the $\mu$ and $\tau$ channels. Sizeable deviations from the SM values are obtained. Hence, b \rar s \ell^+ \ell^- decay is a valuable tool for searching physics beyond the SM, especially in the indirect searches for the fourth-generation of quarks ($t', b')$.Comment: 19 Pages, 10 Figures, 3 Table

A renormalizable SO(10) GUT scenario with spontaneous CP violation

We consider fermion masses and mixings in a renormalizable SUSY SO(10) GUT with Yukawa couplings of scalar fields in the representation 10 + 120 + 126 bar. We investigate a scenario defined by the following assumptions: i) A single large scale in the theory, the GUT scale. ii) Small neutrino masses generated by the type I seesaw mechanism with negligible type II contributions. iii) A suitable form of spontaneous CP breaking which induces hermitian mass matrices for all fermion mass terms of the Dirac type. Our assumptions define an 18-parameter scenario for the fermion mass matrices for 18 experimentally known observables. Performing a numerical analysis, we find excellent fits to all observables in the case of both the normal and inverted neutrino mass spectrum.Comment: 16 pages, two eps figure

SUSY GUT Model Building

I discuss an evolution of SUSY GUT model building, starting with the construction of 4d GUTs, to orbifold GUTs and finally to orbifold GUTs within the heterotic string. This evolution is an attempt to obtain realistic string models, perhaps relevant for the LHC. This review is in memory of the sudden loss of Julius Wess, a leader in the field, who will be sorely missed.Comment: 24 pages, 14 figures, lectures given at PiTP 2008, Institute for Advanced Study, Princeton, to be published in the European Physical Journal

To wet or not to wet: that is the question

Wetting transitions have been predicted and observed to occur for various combinations of fluids and surfaces. This paper describes the origin of such transitions, for liquid films on solid surfaces, in terms of the gas-surface interaction potentials V(r), which depend on the specific adsorption system. The transitions of light inert gases and H2 molecules on alkali metal surfaces have been explored extensively and are relatively well understood in terms of the least attractive adsorption interactions in nature. Much less thoroughly investigated are wetting transitions of Hg, water, heavy inert gases and other molecular films. The basic idea is that nonwetting occurs, for energetic reasons, if the adsorption potential's well-depth D is smaller than, or comparable to, the well-depth of the adsorbate-adsorbate mutual interaction. At the wetting temperature, Tw, the transition to wetting occurs, for entropic reasons, when the liquid's surface tension is sufficiently small that the free energy cost in forming a thick film is sufficiently compensated by the fluid- surface interaction energy. Guidelines useful for exploring wetting transitions of other systems are analyzed, in terms of generic criteria involving the "simple model", which yields results in terms of gas-surface interaction parameters and thermodynamic properties of the bulk adsorbate.Comment: Article accepted for publication in J. Low Temp. Phy

Cosmic acceleration from second order gauge gravity

We construct a phenomenological theory of gravitation based on a second order gauge formulation for the Lorentz group. The model presents a long-range modification for the gravitational field leading to a cosmological model provided with an accelerated expansion at recent times. We estimate the model parameters using observational data and verify that our estimative for the age of the Universe is of the same magnitude than the one predicted by the standard model. The transition from the decelerated expansion regime to the accelerated one occurs recently (at $\sim9.3\;Gyr$).Comment: RevTex4 15 pages, 1 figure. Accepted for publication in Astrophysics & Space Scienc

Tomonaga-Luttinger parameters for quantum wires

The low-energy properties of a homogeneous one-dimensional electron system are completely specified by two Tomonaga-Luttinger parameters $K_{\rho}$ and $v_{\sigma}$. In this paper we discuss microscopic estimates of the values of these parameters in semiconductor quantum wires that exploit their relationship to thermodynamic properties. Motivated by the recognized similarity between correlations in the ground state of a one-dimensional electron liquid and correlations in a Wigner crystal, we evaluate these thermodynamic quantities in a self-consistent Hartree-Fock approximation. According to our calculations, the Hartree-Fock approximation ground state is a Wigner crystal at all electron densities and has antiferromagnetic order that gradually evolves from spin-density-wave to localized in character as the density is lowered. Our results for $K_{\rho}$ are in good agreement with weak-coupling perturbative estimates $K_{\rho}^{pert}$ at high densities, but deviate strongly at low densities, especially when the electron-electron interaction is screened at long distances. $K_{\rho}^{pert}\sim n^{1/2}$ vanishes at small carrier density $n$ whereas we conjecture that $K_{\rho}\to 1/2$ when $n\to 0$, implying that $K_{\rho}$ should pass through a minimum at an intermediate density. Observation of such a non-monotonic dependence on particle density would allow to measure the range of the microscopic interaction. In the spin sector we find that the spin velocity decreases with increasing interaction strength or decreasing $n$. Strong correlation effects make it difficult to obtain fully consistent estimates of $v_{\sigma}$ from Hartree-Fock calculations. We conjecture that v_{\sigma}/\vf\propto n/V_0 in the limit $n\to 0$ where $V_0$ is the interaction strength.Comment: RevTeX, 23 pages, 8 figures include