Geology, geochronology and isotopic geochemistry of the Xiaoliugou W-Mo ore field in the Qilian Orogen, NW China : case study of a skarn system formed during continental collision

This study is financially supported by the National Natural Science Foundation of China (41502068).The Xiaoliugou W-Mo ore field lies within the mid-Paleozoic North Qilian Orogen, NW China, and hosts a W resource of 48.8 Mt @ 0.4% and 412.6 Mt of Mo @ 0.075%. It contains five deposits, including Xiaoliugou, Qiqing, Guishan, Qibao and Shiji. The main mineralization styles at Xiaoliugou are skarn and veins in which the mineral sequence is scheelite > molybdenite > chalcopyrite and occurs in the endo- and exo-contact zones of granite intrusions. The scheelite-dominated orebodies are overprinted by molybdenite-dominated quartz veins. Two molybdenite samples yielded Silurian Re-Os model ages of 427.4 ± 6.0 Ma and 428.2 ± 6.0 Ma. Three muscovite samples coexisting with molybdenite yielded Middle Devonian Ar-Ar ages of 392.0 ± 2.7 Ma, 391.1 ± 2.7 Ma and 391.4 ± 2.8 Ma. The Re-Os and Ar-Ar ages indicate that the W-Mo mineralization and alteration occurred at ca. 428–391 Ma, which corresponds with regional continental collision within the Qilian Orogen. δ34S for the sulfides molybdenite and pyrite are 7.70–11.67 ‰ and 4.98–13.17 ‰, respectively. The 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb of the sulfides are 17.98–21.73, 15.34–18.81, and 37.18–38.63, respectively. The granites yield similar corrected (206Pb/204Pb)i, (207Pb/204Pb)i and (208Pb/204Pb)i, ranging 16.14–19.35, 15.44–15.63, and 37.41–38.31, respectively. Calculated δ18O of the fluid inclusions in quartz range from -3.38–2.34 ‰, whereas the δD of the hydrothermal fluids ranges from -94 to -47 ‰. The S-, Pb-, O- and D-isotopic data imply that the metals originated from the granite intrusion with a minor component sourced from the host sediments, and that the ore-forming fluids were dominated by magmatic-hydrothermal fluids mixed with minor meteoric water.PostprintPeer reviewe

The Role of Contagion in the Last American Housing Cycle

Using proprietary micro data on the complete set of housing transactions between 1993 and 2009 in 99 metropolitan areas, we investigate whether contagion was an important factor in the last housing cycle. We define contagion as the price correlation between two different housing markets following a shock to one market that is above and beyond that which can be justified by common aggregate trends. Our estimates deal with the following empirical challenges: (a) defining the timing of local housing booms in a non-ad hoc way; (b) addressing specification search bias that arises when only one aggregate series is used to estimate both the timing of the housing boom and the magnitude of price volatility during that period; and (c) controlling for common variation in economic conditions. We find strong evidence of contagion during the housing boom, but not during the bust. These effects appear to arise mostly from the closest neighboring metropolitan area, with the price elasticity ranging from 0.10 to 0.27. This is large enough to account for up to 30% of the jump in prices at the beginning of local booms, on average. Estimated elasticities are greater when transmitted from a larger to a smaller market, and also more important for the most elastically-supplied markets. Finally, local fundamentals and expectations of future fundamentals have very limited ability to account for our estimated effect, suggesting a potential role for non-rational forces

Generation and sampling of quantum states of light in a silicon chip

Implementing large instances of quantum algorithms requires the processing of many quantum information carriers in a hardware platform that supports the integration of different components. While established semiconductor fabrication processes can integrate many photonic components, the generation and algorithmic processing of many photons has been a bottleneck in integrated photonics. Here we report the on-chip generation and processing of quantum states of light with up to eight photons in quantum sampling algorithms. Switching between different optical pumping regimes, we implement the Scattershot, Gaussian and standard boson sampling protocols in the same silicon chip, which integrates linear and nonlinear photonic circuitry. We use these results to benchmark a quantum algorithm for calculating molecular vibronic spectra. Our techniques can be readily scaled for the on-chip implementation of specialised quantum algorithms with tens of photons, pointing the way to efficiency advantages over conventional computers

Improving musculoskeletal model scaling using an anatomical atlas:the importance of gender and anthropometric similarity to quantify joint reaction forces

Objective: The accuracy of a musculoskeletal model relies heavily on the implementation of the underlying anatomical dataset. Linear scaling of a generic model, despite being time and cost-efficient, produces substantial errors as it does not account for gender differences and inter-individual anatomical variations. The hypothesis of this study is that linear scaling to a musculoskeletal model with gender and anthropometric similarity to the individual subject produces similar results to the ones that can be obtained from a subject-specific model. Methods: A lower limb musculoskeletal anatomical atlas was developed consisting of ten datasets derived from magnetic resonance imaging of healthy subjects and an additional generic dataset from the literature. Predicted muscle activation and joint reaction force were compared with electromyography and literature data. Regressions based on gender and anthropometry were used to identify the use of atlas. Results: Primary predictors of differences for the joint reaction force predictions were mass difference for the ankle (p<0.001) and length difference for the knee and hip (p≤0.017) . Gender difference accounted for an additional 3% of the variance (p≤0.039) . Joint reaction force differences at the ankle, knee and hip were reduced by between 50% and 67% (p=0.005) when using a musculoskeletal model with the same gender and similar anthropometry in comparison with a generic model. Conclusion: Linear scaling with gender and anthropometric similarity can improve joint reaction force predictions in comparison with a scaled generic model. Significance: The scaling approach and atlas presented can improve the fidelity and utility of musculoskeletal models for subject-specific applications

Has China gained significant influence over ASEAN? : from the golden decade to the diamond decade

published_or_final_versionInternational and Public AffairsMasterMaster of International and Public Affair

Benzene Metabolite, Hydroquinone, Activates the Aryl Hydrocarbon Receptor Pathway in Trophoblasts

Introduction: Benzene is the 6th most produced chemical in the world and a major pollutant that has been shown to have adverse effects on pregnancy. We previously showed that maternal benzene exposure during pregnancy induces maternal immune activation and also leads to an increase in fetal reabsorptions. The molecular mechanism in which benzene induces these negative effects is poorly understood. Here we developed a cellular model of benzene exposure to understand the molecular effect of benzene on trophoblast cells. Specifically, cells were exposed hydroquinone, a major benzene metabolite, in order to determine the molecular mechanism behind the observed maternal immune activation during benzene exposure. Method: Trophoblast cells (Sw.71) were exposed to 25μM of hydroquinone for 2, 4, 8, 16, 24 and 48 hours. Cells were collected at the time intervals specified above for RNA extraction and qPCR analysis. Results: Our data has shown that: 1) hydroquinone treatment activates AhR pathway as CYP1A1 is significantly induced in trophoblast cells; 2) hydroquinone treatment leads to inflammation in the trophoblast cells, which is shown as the significant increase of IL-6 and IL1- gene expression 24 hours after treatment; 3) hydroquinone treatment has a major impact on the ER stress that we reveal increased CHOP expression as early as 2 hours and in the later time points. Additionally, we see an initial increase in BIP. However, BIP is decreased at 24 hours of hydroquinone treatment. This expression pattern suggests that ER stress is being induced after hydroquinone treatment in a short time. 4) hydroquinone treatment induces interferon stimulated genes (ISGs) 24 hours after treatment, such as ISG20, Mx1. Conclusion: Our findings indicate that exposure to the major benzene metabolite, hydroquinone, induces activation of the AhR pathway in trophoblast cells. Activation of this pathway is known to lead to inflammation and ER stress. These processes were observed here by increased levels of inflammatory cytokines (IL-6 and IL1-) and transcription of genes associated with the unfolded protein response. Trophoblast cells exposed to hydroquinone also had higher levels of ISGs. The findings here suggest a potential molecular mechanism by which benzene and its metabolites exert detrimental effects on pregnancy

Scaling law for the electromagnetic form factors of the proton

The violation of the scaling law for the electric and magnetic form factors of the proton are examined within the cloudy bag model. The suppression of the ratio of the electric and magnetic form factors is natural in the bag model. The pion cloud plays a moderate role in understanding the recent data from TJNAF.Comment: 8 pages, REVTeX, 2 figures include

Nonlocal Effects on the Magnetic Penetration Depth in d-wave Superconductors

We show that, under certain conditions, the low temperature behavior of the magnetic penetration depth $\lambda(T)$ of a pure d-wave superconductor is determined by nonlocal electrodynamics and, contrary to the general belief, the deviation $\Delta\lambda(T) = \lambda(T)-\lambda(0)$ is proportional to T^2 and not T. We predict that the $\Delta\lambda(T)\propto T^2$ dependence, due to nonlocality, should be observable experimentally in nominally clean high-T_c superconductors below a crossover temperature $T^* = (\xi_o/\lambda_o)\Delta_o \sim 1 K$. Possible complications due to impurities, surface quality and crystal axes orientation are discussed.Comment: REVTeX3.0; 4 pages, 1 EPS figure (included); Submitted to Phys. Rev. Let