Many-body dynamics of a Bose system with attractive interactions on a ring

We investigate the many-body dynamics of an effectively attractive one-dimensional Bose system confined in a toroidal trap. The mean-field theory predicts that a bright-soliton state will be formed when increasing the interparticle interaction over a critical point. The study of quantum many-body dynamics in this paper reveals that there is a modulation instability in a finite Bose system correspondingly. We show that Shannon entropy becomes irregular near and above the critical point due to quantum correlations. We also study the dynamical behavior of the instability by exploring the momentum distribution and the fringe visibility, which can be verified experimentally by releasing the trapComment: 6 pages,5 figure

Anisotropies in insulating La2−x_{2-x}Srx_xCuO4_4: angular resolved photoemission and optical absorption

Due to the orthorhombic distortion of the lattice, the electronic hopping integrals along the $a$ and $b$ diagonals, the orthorhombic directions, are slightly different. We calculate their difference in the LDA and find $t_{a}^{\prime}-t_{b}^{\prime}\approx 8$meV. We argue that electron correlations in the insulating phase of La$_{2-x}$Sr$_{x}$CuO$_{4}$, i. e. at doping $x\leq 0.055,$ dramatically enhance the $(t_{a}^{\prime}-t_{b}^{\prime})$-splitting between the $a$- and $b$-hole valleys. In particular, we predict that the intensity of both angle-resolved photoemission and of optical absorption is very different for the $a$ and $b$ nodal points

Strong correlation and massive spectral-weight redistribution induced spin density wave in a-Fe1.06Te

The electronic structure of a-Fe1.06Te is studied with angle-resolved photoemission spectroscopy. We show that there is substantial spectral weight around Gamma and X, and lineshapes are intrinsically incoherent in the paramagnetic state. The magnetic transition is characterized by a massive spectral-weight transfer over an energy range as large as the band width, which even exhibits a hysteresis loop that marks the strong first order transition. Coherent quasiparticles emerge in the magnetically ordered state due to decreased spin fluctuations, which account for the change of transport properties from insulating behavior to metallic behavior. Our observation demonstrates that Fe1.06Te distinguishes itself from other iron-based systems with more local characters and much stronger interactions among different degrees of freedom, and how a spin density wave is formed in the presence of strong correlation.Comment: 5 pages, 4 figure

A multitemporal remote sensing approach to parsimonious streamflow modeling in a southcentral Texas watershed, USA

International audienceSoil moisture condition plays a vital role in a watershed's hydrologic response to a precipitation event and is thus parameterized in most, if not all, rainfall-runoff models. Yet the soil moisture condition antecedent to an event has proven difficult to quantify both spatially and temporally. This study assesses the potential to parameterize a parsimonious streamflow prediction model solely utilizing precipitation records and multi-temporal remotely sensed biophysical variables (i.e.~from Moderate Resolution Imaging Spectroradiometer (MODIS)/Terra satellite). This study is conducted on a 1420 km2 rural watershed in the Guadalupe River basin of southcentral Texas, a basin prone to catastrophic flooding from convective precipitation events. A multiple regression model, accounting for 78% of the variance of observed streamflow for calendar year 2004, was developed based on gauged precipitation, land surface temperature, and enhanced vegetation Index (EVI), on an 8-day interval. These results compared favorably with streamflow estimations utilizing the Natural Resources Conservation Service (NRCS) curve number method and the 5-day antecedent moisture model. This approach has great potential for developing near real-time predictive models for flood forecasting and can be used as a tool for flood management in any region for which similar remotely sensed data are available

Local ventilation for general patient rooms

Numerous studies on ventilation of general patient rooms have been performed, while most of the studies have focused on total volume air distribution (mixing or displacement). This study presents results of local ventilation (LV) aimed to efficiently protect a lying person from cross-infection due to airborne respiratory viruses. Experiments performed in a climate chamber (4.7 m × 4.7 m × 2.6 m) included LV when used alone and when coupled with background mixing ventilation (MV). A thermal manikin and a heated standing dummy were used to simulate respectively a patient lying in bed and an infected doctor or nurse standing beside the bed. The LV was able to reduce substantially the exposure of the patient to the infected air exhaled by the doctor. The results show that the efficiency of the LV depended mostly on its supply airflow rate. An increase of the background ventilation's supply flow rate, i.e. increase of the air change rate in the room, was less important. At 15 L/s supplied by LV the concentration of a contaminant at the patient's mouth decreased by 76%. The findings of the paper give insights for researchers and designers in developing a novel ventilation system to be used during a pandemic in general patient rooms.publishedVersio