Finite size effects, super-and sub-poissonian noise in a nanotube connected to leads

The injection of electrons in the bulk of carbon nanotube which is connected to ideal Fermi liquid leads is considered. While the presence of the leads gives a cancellation of the noise cross-correlations, the auto-correlation noise has a Fano factor which deviates strongly from the Schottky behavior at voltages where finite size effects are expected. Indeed, as the voltage is increased from zero, the noise is first super-poissonian, then sub-poissonian, and eventually it reaches the Schottky limit. These finite size effects are also tested using a diagnosis of photo-assisted transport, where a small AC modulation is superposed to the DC bias voltage between the injection tip and the nanotube. When finite size effects are at play, we obtain a stepwise behavior for the noise derivative, as expected for normal metal systems, whereas in the absence of finite size effects, due to the presence of Coulomb interactions, a smoothed staircase is observed. The present work shows that it is possible to explore finite size effects in nanotube transport via a zero frequency noise measurement

Screening of a Luttinger liquid wire by a scanning tunneling microscope tip: I. Spectral properties

The screening effect due to a scanning tunneling microscope tip which is placed in the vicinity of an interacting quantum wire is considered. With the help of a bosonization procedure, we are able to determine non perturbatively the Green's functions of the quantum wire in the presence of both electrostatic screening by the tip and Coulomb interactions in the wire. In our approach we justify that the working Hamiltonian of the whole system is quadratic when $K_c>1/2$ and can be solved by integration over the degrees of freedom of the tip. Once the Green's functions are known, we calculate the spectral properties. We show that the spectral function, as well as the tunnel density of states, is affected by the screening and that the local density of states strongly deviates from its unscreened value when the tip gets close to the wire. Moreover, we observe that the spatial extension of the deviation of the local density of states is related to both the Coulomb interactions parameter and the screening strength

Using models to inform water policy in a changing climate: comparing the Australian and Uruguayan experiences

Mitigating the expansion of harmful cyanobacterial blooms in Uruguayan catchments is a major challenge facing researchers and decision makers. To make matters worse, these events are expected to occur more often as the climate changes. Taking Australia’s experience as an example, minimising the effect of algal blooms involves a range of catchment land use policy and regulatory measures that are underpinned by comprehensive monitoring systems, hydrological modelling platforms and land suitability analysis considering the effects of climate change. The lack of these technological tools means that policies and regulations cannot be implemented effectively. In this paper, we analyse the effects of climate change on Laguna Del Sauce Catchment (Uruguay) and discuss the effects of a possible new land use configuration defined using approaches typically used in Australia. We identify that the likely future of the catchment, according to biophysical modelling, is in conflict with its likely future as defined by its existing land use trajectory and associated agricultural policy. Our analysis provides new insights into the possible effects of climate change on Laguna Del Sauce, and thus fills an important knowledge gap to inform and amend the current policies and institutional frameworks