ASoP (v1.0): a set of methods for analyzing scales of precipitation in general circulation models

General circulation models (GCMs) have been criticized for their failure to represent the observed scales of precipitation, particularly in the tropics where simulated daily rainfall is too light, too frequent, and too persistent. Previous assessments have focused on temporally or spatially averaged precipitation, such as daily means or regional averages. These evaluations offer little actionable information for model developers, because the interactions between the resolved dynamics and parameterized physics that produce precipitation occur at the native gridscale and timestep. We introduce a set of diagnostics (ASoP1) to compare the spatial and temporal scales of precipitation across GCMs and observations, which can be applied to data ranging from the gridscale and timestep to regional and sub-monthly averages. ASoP1 measures the spectrum of precipitation intensity, temporal variability as a function of intensity, and spatial and temporal coherence. When applied to timestep, gridscale tropical precipitation from ten GCMs, the diagnostics reveal that far from the "dreary" persistent light rainfall implied by daily mean data, most models produce a broad range of timestep intensities that span 1-100 mm/day. Models show widely varying spatial and temporal scales of timestep precipitation. Several GCMs show concerning quasi-random behavior that may influence alter the spectrum of atmospheric waves. Averaging precipitation to a common spatial (~600 km) or temporal (3-hr) resolution substantially reduces variability among models, demonstrating that averaging hides a wealth of information about intrinsic model behavior. When compared against satellite-derived analyses at these scales, all models produce features that are too large and too persistent

Correlation of Matrix Metalloproteinases and Tissue Inhibitors of Matrix Metalloproteinase Expression in Ileal Carcinoids, Lymph Nodes and Liver Metastasis with Prognosis and Survival

Purpose: Ileal carcinoids are gut epithelial tumors originating from serotonin-containing enterochromaffin (EC) cells. Therapeutic options for effectively inhibiting the growth and spread of metastatic carcinoids are still limited. We aimed to identify the role of matrix metalloproteinases (MMPs) and their endogenous tissue inhibitors (TIMPs) during tumor development and metastasis. Patients and Methods: Tissue samples were obtained from surgically treated patients. Expression of the EC-cell marker, vesicular monoamine transporter-1 (VMAT-1), was used to verify ileal carcinoids. We investigated the differential expression of MMP-2, 7, 9, 11, and 13 and their endogenous inhibitors (TIMP-1, 2, and 3) by quantitative real-time RT-PCR in 25 primary tumors, their corresponding lymph node metastases and/or liver metastases and matched normal mucosa. Results: Significantly increased expression of VMAT-1, MMP-2, MMP-11, TIMP-1 and TIMP-3 was determined by quantitative RT-PCR in EC-cell carcinoids compared to normal intestinal mucosa (p < 0.05). In contrast, MMP-2 and MMP-9 as well as TIMP-1, TIMP-2, and TIMP-3 expression in primary tumors of patients with liver metastases (M1) was significantly lower than in patients lacking liver metastases (M0). EC-cell tumors were significantly larger in the M1 group of tumors, while VMAT-1 expression was significantly decreased. We found an inverse correlation between tumor size and prognosis. Univariate analysis further revealed that decreased expression of VMAT-1, MMP-2 and TIMP-3 in primary tumors was significantly associated with a reduced survival time of the patients. Conclusion: Our data reveal that MMP-2 and TIMP-3 expression together with VMAT-1 expression are of potential prognostic and clinical value in ileal carcinoids. Copyright (C) 2008 S. Karger AG, Base

Zero Temperature Thermodynamics of Asymmetric Fermi Gases at Unitarity

The equation of state of a dilute two-component asymmetric Fermi gas at unitarity is subject to strong constraints, which affect the spatial density profiles in atomic traps. These constraints require the existence of at least one non-trivial partially polarized (asymmetric) phase. We determine the relation between the structure of the spatial density profiles and the T=0 equation of state, based on the most accurate theoretical predictions available. We also show how the equation of state can be determined from experimental observations.Comment: 10 pages and 7 figures. (Minor changes to correspond with published version.

Spin 1/2 Fermions in the Unitary Regime: A Superfluid of a New Type

We have studied, in a fully non-perturbative calculation, a dilute system of spin 1/2 interacting fermions, characterized by an infinite scattering length at finite temperatures. Various thermodynamic properties and the condensate fraction were calculated and we have also determined the critical temperature for the superfluid-normal phase transition in this regime. The thermodynamic behavior appears as a rather surprising and unexpected melange of fermionic and bosonic features. The thermal response of a spin 1/2 fermion at the BCS-BEC crossover should be classified as that of a new type of superfluid.Comment: 4 pages, 1 figure, published versio

Thermodynamics of a Trapped Unitary Fermi Gas

We present the first model-independent comparison of recent measurements of the entropy and of the critical temperature of a unitary Fermi gas, performed by Luo et al., with the most complete results currently available from finite temperature Monte Carlo calculations. The measurement of the critical temperature in a cold fermionic atomic cloud is consistent with a value $T_c=0.23(2)epsilon_F$ in the bulk, as predicted by the present authors in their Monte Carlo calculations.Comment: 5 pages, 4 figures, published versio

Connecting spatial and temporal scales of tropical precipitation in observations and the MetUM-GA6

This study analyses tropical rainfall variability, on a range of temporal and spatial scales, in a set of parallel Met Office Unified Model (MetUM) simulations at a range of horizontal resolutions, compared with two satellite-derived rainfall datasets. We focus on the shorter scales i.e. from the native grid and time-step of the model through sub-daily to seasonal, since previous studies have paid relatively little attention to sub-daily rainfall variability and how this feeds through to longer scales. We find that the behaviour of the deep convection parametrization in this model on the native grid and time-step is largely independent of the grid-box size and time-step length over which it operates. There is also little difference in the rainfall variability on larger/longer spatial/temporal scales. Tropical convection in the model on the native grid/time-step is spatially and temporally intermittent, producing very large rainfall amounts interspersed with grid-boxes/time-steps of little or no rain. In contrast, switching off the deep convection parametrization, albeit at an unrealistic resolution for resolving tropical convection, results in very persistent (for limited periods), but very sporadic, rainfall. In both cases, spatial and temporal averaging smoothes out this intermittency. On the ~100 km scale, for oceanic regions, the spectra of 3-hourly and daily mean rainfall in the configurations with parametrized convection agree fairly well with those from satellite-derived rainfall estimates, while at ~10 day timescales the averages are overestimated, indicating a lack of intra-seasonal variability. Over tropical land the results are more varied, but the model often underestimates the daily mean rainfall (partly as a result of a poor diurnal cycle) but still lacks variability on intra-seasonal timescales. Ultimately, such work will shed light on how uncertainties in modelling the small/short scale processes relate to uncertainty in climate change projections of rainfall distribution and variability, with a view to reducing such uncertainty through improved modelling of the small/short scale processes

Induced P-wave Superfluidity in Asymmetric Fermi Gases

We show that two new intra-species P-wave superfluid phases appear in two-component asymmetric Fermi systems with short-range S-wave interactions. In the BEC limit, phonons of the molecular BEC induce P-wave superfluidity in the excess fermions. In the BCS limit, density fluctuations induce P-wave superfluidity in both the majority and the minority species. These phases may be realized in experiments with spin-polarized Fermi gases.Comment: published versio

On the specific heat of a fermionic atomic cloud in the unitary regime

In the unitary regime, when the scattering amplitude greatly exceeds in magnitude the average inter-particle separation, and below the critical temperature thermal properties of an atomic fermionic cloud are governed by the collective modes, specifically the Bogoliubov-Anderson sound modes. The specific heat of an atomic cloud in a elongated trap in particular has a rather compex temperature dependence, which changes from an exponential behavior at very low temperatures ($T\ll\hbar\omega_{||}$), to $\propto T$ for $\hbar\omega_{||}\ll T \ll \hbar\omega_\perp$ and then continuosly to $\propto T^4$ at temperatures just below the critical temperature, when the surface modes play a dominant role. Only the low ($\hbar\omega_{||} \ll T \ll \hbar\omega_\perp$) and high ($\hbar\omega_\perp \ll T < T_c$) temperature power laws are well defined. For the intermediate temperatures one can introduce at most a gradually increasing with temperature exponent.Comment: 4 page

The Vortex State in a Strongly Coupled Dilute Atomic Fermionic Superfluid

We show that in a dilute Fermionic superfluid, when the Fermions interact with an infinite scattering length, a vortex state is characterized by a strong density depletion along the vortex core. This feature can make a direct visualization of vortices in Fermionic superfluids possible.Comment: 4 pages, 3 figures, published version, some small changes and new and updated reference