A Graphene Field-Effect Device

In this letter, a top-gated field effect device (FED) manufactured from monolayer graphene is investigated. Except for graphene deposition, a conventional top-down CMOS-compatible process flow is applied. Carrier mobilities in graphene pseudo-MOS structures are compared to those obtained from top-gated Graphene-FEDs. The extracted values exceed the universal mobility of silicon and silicon-on-insulator MOSFETs.Comment: 12 pages, 3 figure

Symmetry breaking in the self-consistent Kohn-Sham equations

The Kohn-Sham (KS) equations determine, in a self-consistent way, the particle density of an interacting fermion system at thermal equilibrium. We consider a situation when the KS equations are known to have a unique solution at high temperatures and this solution is a uniform particle density. We show that, at zero temperature, there are stable solutions that are not uniform. We provide the general principles behind this phenomenon, namely the conditions when it can be observed and how to construct these non-uniform solutions. Two concrete examples are provided, including fermions on the sphere which are shown to crystallize in a structure that resembles the C$_{60}$ molecule.Comment: a few typos eliminate

Sum rules for correlation functions of ionic mixtures in arbitrary dimension d≥2d\geq 2

The correlations in classical multi-component ionic mixtures with spatial dimension $d\geq 2$ are studied by using a restricted grand-canonical ensemble and the associated hierarchy equations for the correlation functions. Sum rules for the first few moments of the two-particle correlation function are derived and their dependence on $d$ is established. By varying $d$ continuously near $d=2$ it is shown how the sum rules for the two-dimensional mixture are related to those for mixtures at higher $d$.Comment: 19 page

LATE SUMMER-EARLY FALL PHOTOSYNTHESIS IN COTTONWOOD

Photosynthesis was investigated during late summer and early fall in a population of mature cottonwood (Populus deltoides) trees growing on the campus of MSU-Billings in southcentral Montana. Parameters related to photosynthesis were measured in situ with a Licor 6400XT Photosynthesis system. A diurnal fluctuation in assimilation was observed with a peak value of 17.0 uM m-2 s-1 CO2 fixed during mid-day. We examined the capacity for assimilation at a PAR of 4000 uM m-2 s-1 (approx. 200% full sunlight) and observed assimilation values as high as 17.6 uM CO2 m-2 s-1 with no indication of photoinhibition. P.deltoides also responded to high ambient CO2 (1600 umol M-1) where assimilation increased to 31.5 umol CO2 m-2 s-1 under 1000 uM m-2 s-1 PAR.  We used an ACi curve fitting utility to obtain values of 104 mmol m-2 s-1, 117 mmol m-2 s-1 and 8.6 mmol m-2 s-1 for rubisco Vcmax, electron flow rate and triose phosphate utilization, respectively. Transpiration was 0.1-6.1 mmol m-2 s-1 and correlated with assimilation. Assimilation declined 37% from the earliest measurements on 23Sep to those taken on 15Oct. We conclude that photosynthesis continues in leaves of P.deltoides well into autumn despite shorter days and cooler temperatures, but with an adaptive response resulting in less CO2 fixation. Leaves can photosynthetically fix carbon, presumably stored as reserve carbohydrates well into late fall before the onset of autumnal leaf senescence

Structure of the Local-field factor of the 2-D electron fluid. Possible evidence for correlated scattering of electron pairs

The static local-field factor (LFF) of the 2-D electron fluid is calculated {\it nonperturbatively} using a mapping to a classical Coulomb fluid $\lbrack$Phys. Rev. Lett., {\bf 87}, 206$\rbrack$. The LFF for the paramagnetic fluid {\it differs markedly} from perturbation theory where a maximum near 2$k_F$ is expected. Our LFF has a quasi-linear small-k region leading to a maximum close to 3$k_F$, in agreent with currently available quantum Monte Carlo data. The structure in the LFF and its dependence on the density and temperature are interpretted as a signature of correlated scattering of electron pairs of opposite spin.The lack of structure at $2k_F$ implies weakened Friedel oscillations, Kohn anomalies etc.Comment: 4 pages, 3 figures, version 2 of condmat/0304034, see http://nrcphy1.phy.nrc.ca/ims/qp/chandre/chnc/ Changs in the text, figure 2 and updated reference

Spin-polarized stable phases of the 2-D electron fluid at finite temperatures

The Helmholtz free energy F of the interacting 2-D electron fluid is calculated nonperturbatively using a mapping of the quantum fluid to a classical Coulomb fluid [Phys. Rev. Letters, vol. 87, 206404 (2001)]. For density parameters rs such that rs<~25, the fluid is unpolarized at all temperatures t=T/EF where EF is the Fermi energy. For lower densities, the system becomes fully spin polarized for t<~0.35, and partially polarized for 0.35<t< 2, depending on the density. At rs ~25-30, and t ~0.35, an ''ambispin'' phase where F is almost independent of the spin polarization is found. These results support recent claims, based on quantum Monte Carlo results, for a stable, fully spin-polarized fluid phase at T = 0 for rs larger than about 25-26.Comment: Latex manuscript (4-5 pages) and two postscript figures; see also http://nrcphy1.phy.nrc.ca/ims/qp/chandre/chnc

Heterogeneities in Supercooled liquids: A Density Functional Study

A metastable state, characterized by a low degree of mass localization is identified using Density Functional Theory. This free energy minimum, located through the proper evaluation of the competing terms in the free energy functional, is independent of the specific form of the DFT used. Computer simulation results on particle motion indicate that this heterogeneous state corresponds to the supercooled state.Comment: 10 pages, 6 figure

Novel Expression Patterns for Trefoil Peptides: Presence of Tff2 and Tff3 in Rodent Cochlea

Trefoil peptides: Tff1, Tff2 and Tff3, assigned to the so-called trefoil factor family (TFF), are secretory proteins predominantly expressed by the gastrointestinal (GI) epithelial cells. Their multiple protective functions include an important role in immune response and apoptosis. Here, a novel localization of Tff2 and Tff3 in the cochlea of mouse inner ear is presented. Tffs expression and localization in mouse cochlea was analyzed by using the quantitative real time PCR (qPCR) and immunohistochemistry. Tff2 and Tff3 mRNA quantification by qPCR showed their presence in the cochlea. Immunohistochemistry demonstrated the presence of Tff2 in the spiral ligament and limbus and for Tff3 in the spiral ligament and the organ of Corti. These new and surprising findings of Tff’s presence in the cochlea indicate a new role of TFFs connected with the organ of hearing which still needs to be physiologically evaluated

Description of Atmospheric Conditions at the Pierre Auger Observatory Using Meteorological Measurements and Models

Atmospheric conditions at the site of a cosmic ray observatory must be known well for reconstructing observed extensive air showers, especially when measured using the fluorescence technique. For the Pierre Auger Observatory, a sophisticated network of atmospheric monitoring devices has been conceived. Part of this monitoring was a weather balloon program to measure atmospheric state variables above the Observatory. To use the data in reconstructions of air showers, monthly models have been constructed. Scheduled balloon launches were abandoned and replaced with launches triggered by high-energetic air showers as part of a rapid monitoring system. Currently, the balloon launch program is halted and atmospheric data from numerical weather prediction models are used. A description of the balloon measurements, the monthly models as well as the data from the numerical weather prediction are presented

Self-consistent Overhauser model for the pair distribution function of an electron gas at finite temperature

We present calculations of the spin-averaged pair distribution function $g(r)$ in a homogeneous gas of electrons moving in dimensionality D=3 or D=2 at finite temperature. The model involves the solution of a two-electron scattering problem via an effective potential which embodies many-body effects through a self-consistent Hartree approximation, leading to two-body wave functions to be averaged over a temperature-dependent distribution of relative momentum for electron pairs. We report illustrative numerical results for $g(r)$ in an intermediate-coupling regime and interpret them in terms of changes of short-range order with increasing temperature.Comment: 6 pages, 5 figures, submitted to Solid State Communication