127 research outputs found
Evaluation de la qualité des eaux de puits à usage domestique dans les quartiers défavorisés de quatre communes d’Abidjan (Côte d’Ivoire) : Koumassi, Marcory, Port-Bouet et Treichville
La qualité des eaux de puits à usages domestiques dans les quartiers précaires de quatre communes de la ville d’Abidjan a été étudiée à travers l’analyse des paramètres physico-chimiques et microbiologiques couramment utilisés pour la qualité de l’eau de consommation. Les concentrations en nitrates varient entre 0 et 286 mg/L et celles de l’ammonium entre 3,6 et 39,6 mg/L. Plus de 80% des puits ont des teneurs en nitrates supérieures à la norme de 50 mg/L requise, ce qui traduit que les eaux sont d’une mauvaise qualité pour la boisson, mais subissent l’impact d’une insalubrité urbaine. En plus, la qualité des eaux de puits est variable et dépend d’un certain nombre de facteurs tels que l’emplacement des puits par rapport aux sources de contamination urbaines endogènes. La dégradation de la qualité des eaux est fortement impactée par le défaut d’assainissement des quartiers précaires. L’interprétation des données d’analyse, la corrélation existante entre les eaux de puits et la répartition des eaux de puits en groupes sont réalisées en utilisant l’Analyse en Composante Principale Normée (ACPN). Plusieurs facteurs conditionnent la contamination des eaux de puits par les polluants minéraux tels que NO3 -, NH4 +, SO4 2- et Cl-. Le défaut d’assainissement dans ces quartiers, la mauvaise gestion des déchets urbains, la faible profondeur de la nappe, la nature des sols et la perméabilité de l’aquifère exploité sont les preuves de la vulnérabilité des eaux des puits. En effet, les résultats acquis font ressortir la forte influence de l’activité urbaine sur la qualité de ces eaux qui sont fortement chargées en ions nitrates et ammonium, signe d’une pollution urbaine. © 2010 International Formulae Group. All rights reserved.Mots clés : Pollution, eaux de puits, assainissement, analyse en composante principale normée, sels dissous
Assessment of ion kinetic effects in shock-driven inertial confinement fusion implosions using fusion burn imaging
The significance and nature of ion kinetic effects in D3He-filled, shock-driven inertial confinement
fusion implosions are assessed through measurements of fusion burn profiles. Over this series of
experiments, the ratio of ion-ion mean free path to minimum shell radius (the Knudsen number,
NK) was varied from 0.3 to 9 in order to probe hydrodynamic-like to strongly kinetic plasma
conditions; as the Knudsen number increased, hydrodynamic models increasingly failed to match
measured yields, while an empirically-tuned, first-step model of ion kinetic effects better captured
the observed yield trends [Rosenberg et al., Phys. Rev. Lett. 112, 185001 (2014)]. Here, spatially
resolved measurements of the fusion burn are used to examine kinetic ion transport effects in
greater detail, adding an additional dimension of understanding that goes beyond zero-dimensional
integrated quantities to one-dimensional profiles. In agreement with the previous findings, a comparison
of measured and simulated burn profiles shows that models including ion transport effects
are able to better match the experimental results. In implosions characterized by large Knudsen
numbers (NK3), the fusion burn profiles predicted by hydrodynamics simulations that exclude
ion mean free path effects are peaked far from the origin, in stark disagreement with the experimentally
observed profiles, which are centrally peaked. In contrast, a hydrodynamics simulation that
includes a model of ion diffusion is able to qualitatively match the measured profile shapes.
Therefore, ion diffusion or diffusion-like processes are identified as a plausible explanation of the
observed trends, though further refinement of the models is needed for a more complete and
quantitative understanding of ion kinetic effects
Laser-plasma interactions in long-scale-length plasmas under direct-drive National Ignition Facility conditions
Laser-plasma interaction experiments have been carried out on the OMEGA laser system [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] under plasma conditions representative of the peak of a 1.5 MJ direct-drive laser pulse proposed for the National Ignition Facility (NIF). Plasmas have been formed by exploding 18–20 μm thick CH foils and by irradiating solid CH targets from one side, using up to 20 kJ of laser energy with phase plates installed on all beams. These plasmas and the NIF plasmas are predicted to have electron temperatures of 4 keV and density scale lengths close to 0.75 mm at the peak of the laser pulse. The electron temperature and density of the exploding-foil plasmas have been diagnosed using time-resolved x-ray spectroscopy and stimulated Raman scattering, respectively, and are consistent with predictions of the two-dimensional Eulerian hydrodynamics code SAGE [R. S. Craxton and R. L. McCrory, J. Appl. Phys. 56, 108 (1984)]. When the solid-target or exploding-foil plasmas were irradiated with an f/6f/6 interaction beam at 1.5×1015 W/cm2,1.5×1015W/cm2, well above the NIF f/8f/8 cluster intensity of ∼ 2×1014 W/cm2,∼2×1014W/cm2, stimulated Brillouin backscattering (SBS) was found to be completely inhibited. A conservative upper limit of direct-backscattered SRS was found to be ∼5% from the solid targets. SRS and SBS are thus unlikely to have a significant impact on target performance at the peak of the NIF direct-drive laser pulse. © 1999 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70094/2/PHPAEN-6-5-2072-1.pd
Level of Concordance of Pre-, Intra-, and Postoperative Staging in Cervical Cancers (TREYA Study)
Concomitant radiochemotherapy is the therapeutic standard for locally advanced (Ib2 to IVa stage FIGO) cervical cancer. In the absence of a radiotherapy in many of our Sub-Saharan African countries, surgical resection is the only therapeutic method available in hopes of achieving a definite cure. However, criteria for curative surgery are not always met due to preoperative understaging of most of our patients. In addition to socioeconomic factors, the causes for understaging are numerous. These include the lack of personnel or underqualified personnel and the absence of complete workup to assess the resectability of the tumor, but above all the lack of decision-making through multidisciplinary consultation meetings. This study makes a plea in order to provide our hospitals with qualified personnel and adequate technical platform to allow efficient management of our patients with cervical cancer
Using Inertial Fusion Implosions to Measure the T + 3He Fusion Cross Section at Nucleosynthesis-Relevant Energies
Light nuclei were created during big-bang nucleosynthesis (BBN). Standard BBN theory, using rates inferred from accelerator-beam data, cannot explain high levels of [superscript 6]Li in low-metallicity stars. Using high-energy-density plasmas we measure the T([superscript 3]He,γ)[superscript 6]Li reaction rate, a candidate for anomalously high [superscript 6]Li production; we find that the rate is too low to explain the observations, and different than values used in common BBN models. This is the first data directly relevant to BBN, and also the first use of laboratory plasmas, at comparable conditions to astrophysical systems, to address a problem in nuclear astrophysics.United States. Department of Energy (DE-NA0001857)United States. Department of Energy (DE-FC52-08NA28752)United States. Department of Energy (DEFG02-88ER40387)United States. Department of Energy (DE-NA0001837)United States. Department of Energy (DE-AC52- 06NA25396)Lawrence Livermore National Laboratory (B597367)Lawrence Livermore National Laboratory (415935- G)University of Rochester. Fusion Science Center (524431)National Laser User’s Facility (DE-NA0002035)National Science Foundation (U.S.). Graduate Research Fellowship Program (Grant 1122374)Los Alamos National Laboratory. Laboratory Directed Research and Development Program (20150717PRD2
Pembaharuan Proses Pembelajaran Melalui Skema Evaluasi Pada Siswa Sekolah Dasar Inpres Wedomu (Program Pengabdian Masyarakat Mahasiswa Universitas Katolik Widya Mandira di Kabupaten Belu, Nusa Tenggara Timur)
Pandemi covid-19 memberikan dampak yang cukup signifikan termasuk dalam lembaga pendidikan. Pembelajaran secara daring menjadi pilihan yang harus dilakukan agar proses belajar mengajar tetap berjalan sebagaimana mestinya. Proses ini tentu menimbulkan banyak kendala yang dialami hingga berdampak pada menurunnya motivasi belajar siswa. SDI Wedomu merupakan salah satu lembaga pendidikan yang siswa/i-nya mengalami penurunan motivasi belajar akibat pandemic covid-19. Mengacu pada berbagai kendala selama pembelajaran secara daring, maka mahasiswa peserta KKNT-PPM Universitas katolik Widya Mandira memiliki salah satu program kerja utama yakni pengajaran dan pendampingan belajar bagi siswa sekolah dasar, dengan tujuan membangkitkan motivasi belajar siswa pasca pandemi. Fokus dari program ini adalah membantu siswa/i belajar membaca, menulis dan berhitung. Terdapat 5 tahapan dalam rangkaian program kerja ini yakni; observasi lingkungan, kerjasama dengan sekolah mitra, persiapan, pelaksanaan pengajaran dan bimbingan belajar, serta yang terakhir adalah evaluasi. Rangkaian kegiatan ini ditutup dengan adanya kegiatan gebyar literasi yakni lomba menarasikan cerita rakyat dan lomba narasi puisi. Hasil dari program kerja ini walau tidak secara instan membangkitkan motivasi belajar siswa/i, namun semangat belajar berangsur kembali pasca pandemi covid-19. Hal ini dapat dilihat dari siswa/i yang semangat mengerjakan tugas sekolah dan mengikuti pembelajaran dikelas hingga puncaknya adalah mengikuti gebyar literasi
Exploration of the Transition from the Hydrodynamiclike to the Strongly Kinetic Regime in Shock-Driven Implosions
Clear evidence of the transition from hydrodynamiclike to strongly kinetic shock-driven implosions is, for the first time, revealed and quantitatively assessed. Implosions with a range of initial equimolar D[superscript 3]He gas densities show that as the density is decreased, hydrodynamic simulations strongly diverge from and increasingly overpredict the observed nuclear yields, from a factor of ∼2 at 3.1  mg/cm[superscript 3] to a factor of 100 at 0.14  mg/cm[superscript 3]. (The corresponding Knudsen number, the ratio of ion mean-free path to minimum shell radius, varied from 0.3 to 9; similarly, the ratio of fusion burn duration to ion diffusion time, another figure of merit of kinetic effects, varied from 0.3 to 14.) This result is shown to be unrelated to the effects of hydrodynamic mix. As a first step to garner insight into this transition, a reduced ion kinetic (RIK) model that includes gradient-diffusion and loss-term approximations to several transport processes was implemented within the framework of a one-dimensional radiation-transport code. After empirical calibration, the RIK simulations reproduce the observed yield trends, largely as a result of ion diffusion and the depletion of the reacting tail ions.United States. Dept. of Energy (Grant DE-NA0001857)United States. Dept. of Energy (Grant DE-FC52-08NA28752)University of Rochester. Fusion Science Center (5-24431)National Laser User’s Facility (DE-NA0002035)University of Rochester. Laboratory for Laser Energetics (415935-G)Lawrence Livermore National Laboratory (B597367
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Saturation of the Two-Plasmon Decay Instability in Long-Scale-Length Plasmas Relevant to Direct-Drive Inertial Confinement Fusion
Measurements of the hot-electron generation by the two-plasmon-decay instability are made in plasmas relevant to direct-drive inertial confinement fusion. Density-scale lengths of 400 {micro}m at n{sub cr}/4 in planar CH targets allowed the two-plasmon-decay instability to be driven to saturation for vacuum intensities above ~3.5 x 10{sup 14} W cm{sup -2}. In the saturated regime, ~1% of the laser energy is converted to hot electrons. The hot-electron temperature is measured to increase rapidly from 25 to 90 keV as the laser beam intensity is increased from 2 to 7 x 10{sup 14} W cm{sup -2}. This increase in the hot-electron temperature is compared with predictions from nonlinear Zakharov models
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Efficient Coupling of 527 nm Laser Beam Power to a Long Scalelength Plasma
We experimentally demonstrate that application of laser smoothing schemes including smoothing by spectral dispersion (SSD) and polarization smoothing (PS) increases the intensity range for efficient coupling of frequency doubled (527 nm) laser light to a long scalelength plasma with n{sub e}/n{sub cr} = 0.14 and T{sub e} = 2 keV
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