Geophysical investigation and dynamic modelling of unstable slopes: case-study of Kainama (Kyrgyzstan)

The presence of massive Quaternary loess units at the eastern border of the Fergana Basin (Kyrgyzstan, Central Asia) makes this area particularly prone to the development of catastrophic loess earthflows, causing damages and injuries almost every year. Efficient disaster management requires a good understanding of the main causes of these mass movements, that is, increased groundwater pressure and seismic shaking. This paper focuses on the Kainama earthflow, mainly composed of loess, which occurred in 2004 April. Its high velocity and the long run-out zone caused the destruction of 12 houses and the death of 33 people. In summer 2005, a field survey consisting of geophysical and seismological measurements was carried out along the adjacent slope. By combination and geostatistical analysis of these data, a reliable 3-D model of the geometry and properties of the subsurface layers, as shown in the first part of the paper, was created. The analysis of the seismological data allowed us to point out a correlation between the thickness of the loess cover and the measured resonance frequencies and associated amplification potential. The second part of this paper is focused on the study of the seismic response of the slope by numerical simulations, using a 2-D finite difference code named FLAC. Modelling of the seismic amplification potential along the slope confirmed the results obtained from the seismological survey—strong amplifications at the crest and bottom of the slope where there is a thick loess cover and almost no amplification in the middle part of the slope. Furthermore, dynamic slope stability analyses were conducted to assess the influence of local amplifications and increased groundwater pressures on the slope failure. The results of the dynamic modelling, although preliminary, show that a combination of seismic and hydrologic origin (pore pressure build-up during the seismic shaking) is the most probable scenario responsible for the 2004 failur

Strong Anisotropy in Liquid Water upon Librational Excitation using Terahertz Laser Fields

Tracking the excitation of water molecules in the homogeneous liquid is challenging due to the ultrafast dissipation of rotational excitation energy through the hydrogen-bonded network. Here we demonstrate strong transient anisotropy of liquid water through librational excitation using single-color pump-probe experiments at 12.3 THz. We deduce a third order response of chi^3 exceeding previously reported values in the optical range by three orders of magnitude. Using a theory that replaces the nonlinear response with a material response property amenable to molecular dynamics simulation, we show that the rotationally damped motion of water molecules in the librational band is resonantly driven at this frequency, which could explain the enhancement of the anisotropy in the liquid by the external Terahertz field. By addition of salt (MgSO4), the hydration water is instead dominated by the local electric field of the ions, resulting in reduction of water molecules that can be dynamically perturbed by THz pulses

Stabilizing cations in the backbones of conjugated polymers

We synthesized a cross-conjugated polymer containing ketones in the backbone and converted it to a linearly conjugated, cationic polyarylmethine via a process we call "spinless doping" to create a new class of materials, conjugated polyions. This process involves activating the ketones with a Lewis acid and converting them to trivalent cations via the nucleophilic addition of electron-rich aryl moieties. Spinless doping lowers the optical band gap from 3.26 to 1.55 eV while leaving the intrinsic semiconductor properties of the polymer intact. Electrochemical reduction (traditional doping) further decreases the predicted gap to 1.18 eV and introduces radicals to form positive polarons; here, n-doping produces a p-doped polymer in its metallic state. Treatment with a nucleophile (NaOMe) converts the cationic polymer to a neutral, non-conjugated state, allowing the band gap to be tuned chemically, postpolymerization. The synthesis of these materials is carried out entirely without the use of Sn or Pd and relies on scalable Friedel-Crafts chemistry

Enrichment and characterization of dendritic cells from human bronchoalveolar lavages

In the present study about 0.3% to 1.6% of human bronchoalveolar lavage (BAL) cells were identified as typical dendritic cells (DC), having an irregular outline, lobulated nucleus, and clear distinguishable acid phosphatase activity or EBM11 (anti-CD68) reactivity in a spot near the nucleus. After DC enrichment, using transient adherence to plastic, FcR-panning, and a density metrizamide gradient, a population containing 7-8% typical DC was obtained. This DC-enriched low density fraction, containing the highest percentages of DC, very strongly induced T cell proliferation in an allogeneic mixed leucocyte reaction (MLR), which was significantly higher than that induced by other partly (un)fractionated BAL cells. These data indicate that DC seem to be the major accessory cells in the BAL fluid, and therefore may be important in the regulation of T cell immune responses in the lung

Workers' health and productivity under occupational heat strain:a systematic review and meta-analysis

This is an Open Access Article. It is published by Elsevier under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/Background Occupational heat strain (ie, the effect of environmental heat stress on the body) directly threatens workers’ ability to live healthy and productive lives. We estimated the effects of occupational heat strain on workers’ health and productivity outcomes. Methods Following PRISMA guidelines for this systematic review and meta-analysis, we searched PubMed and Embase from database inception to Feb 5, 2018, for relevant studies in any labour environment and at any level of occupational heat strain. No restrictions on language, workers’ health status, or study design were applied. Occupational heat strain was defined using international health and safety guidelines and standards. We excluded studies that calculated effects using simulations or statistical models instead of actual measurements, and any grey literature. Risk of bias, data extraction, and sensitivity analysis were performed by two independent investigators. Six random-effects meta-analyses estimated the prevalence of occupational heat strain, kidney disease or acute kidney injury, productivity loss, core temperature, change in urine specific gravity, and odds of occupational heat strain occurring during or at the end of a work shift in heat stress conditions. The review protocol is available on PROSPERO, registration number CRD42017083271. Findings Of 958 reports identified through our systematic search, 111 studies done in 30 countries, including 447 million workers from more than 40 different occupations, were eligible for analysis. Our meta-analyses showed that individuals working a single work shift under heat stress (defined as wet-bulb globe temperature beyond 22·0 or 24·8°C depending on work intensity) were 4·01 times (95% CI 2·45–6·58; nine studies with 11 582 workers) more likely to experience occupational heat strain than an individual working in thermoneutral conditions, while their core temperature was increased by 0·7°C (0·4–1·0; 17 studies with 1090 workers) and their urine specific gravity was increased by 14·5% (0·0031, 0·0014–0·0048; 14 studies with 691 workers). During or at the end of a work shift under heat stress, 35% (31–39; 33 studies with 13088 workers) of workers experienced occupational heat strain, while 30% (21–39; 11 studies with 8076 workers) reported productivity losses. Finally, 15% (11–19; ten studies with 21721 workers) of individuals who typically or frequently worked under heat stress (minimum of 6 h per day, 5 days per week, for 2 months of the year) experienced kidney disease or acute kidney injury. Overall, this analysis include a variety of populations, exposures, and occupations to comply with a wider adoption of evidence synthesis, but resulted in large heterogeneity in our meta-analyses. Grading of Recommendations, Assessment, Development and Evaluation analysis revealed moderate confidence for most results and very low confidence in two cases (average core temperature and change in urine specific gravity) due to studies being funded by industry. Interpretation Occupational heat strain has important health and productivity outcomes and should be recognised as a public health problem. Concerted international action is needed to mitigate its effects in light of climate change and the anticipated rise in heat stress

Tunable far infrared laser spectroscopy of van der Waals bonds: Vibration–rotation–tunneling spectra of Ar–H2O

The first high resolution spectra of a rare gas–H2O cluster have been observed using a tunable far infrared laser to probe the vibration–rotation–tunneling levels of Ar–H2O formed in a continuous planar supersonic jet. The high sensitivity of this spectrometer facilitated extensive measurements of two perpendicular subbands which are assigned to transitions from the ground state to the upper component of a hydrogen exchange tunneling doublet (c-type) at 21 cm^−1, and to vb1 =1+ (b-type) at 25 cm^−1, the lower tunneling component of a bending vibration which is perpendicular to the tunneling coordinate. The tunneling splitting is shown to be in the range 2.5–7 cm^−1 and the lower tunneling component of the excited bending vibration lies between 39 and 43 cm^−1 above the ground state of the complex. The experimentally determined center-of-mass separation (Rc.m. =3.75 Å) and harmonic stretching force constant (ks =0.0134 mdyn/Å) are compared to those of related first and second row hydrides. The large amplitude motions occurring within this complex make it difficult to establish its structure