A study of the effects of micro-gravity on seed germination

This study will identify characteristics of seed germination dependent upon gravity. To accomplish this objective, four different seed types will be germinated in space and then be compared to a control group germinated on Earth. Both the experimental and control groups will be analyzed on the cellular level for the size of cells, structural anomalies, and gravitational effects. The experiment will be conducted in a Get Away Special Canister (GAS Can no. 608) owned by the U.S. Space and Rocket Center and designed for students. The GAS Can will remain in the cargo bay of the Space Shuttle with minimal astronaut interaction

Collective molecule formation in a degenerate Fermi gas via a Feshbach resonance

We model collisionless collective conversion of a degenerate Fermi gas into bosonic molecules via a Feshbach resonance, treating the bosonic molecules as a classical field and seeding the pairing amplitudes with random phases. A dynamical instability of the Fermi sea against association into molecules initiates the conversion. The model qualitatively reproduces several experimental observations {[Regal et al., Nature {\bf 424}, 47 (2003)]}. We predict that the initial temperature of the Fermi gas sets the limit for the efficiency of atom-molecule conversion.Comment: 4 pages, 3 figures, 10+ references, accepted to PR

Can the Renormalization Group Improved Effective Potential be used to estimate the Higgs Mass in the Conformal Limit of the Standard Model?

We consider the effective potential $V$ in the standard model with a single Higgs doublet in the limit that the only mass scale $\mu$ present is radiatively generated. Using a technique that has been shown to determine $V$ completely in terms of the renormalization group (RG) functions when using the Coleman-Weinberg (CW) renormalization scheme, we first sum leading-log (LL) contributions to $V$ using the one loop RG functions, associated with five couplings (the top quark Yukawa coupling $x$, the quartic coupling of the Higgs field $y$, the SU(3) gauge coupling $z$, and the $SU(2) \times U(1)$ couplings $r$ and $s$). We then employ the two loop RG functions with the three couplings $x$, $y$, $z$ to sum the next-to-leading-log (NLL) contributions to $V$ and then the three to five loop RG functions with one coupling $y$ to sum all the $N^2LL...N^4LL$ contributions to $V$. In order to compute these sums, it is necessary to convert those RG functions that have been originally computed explicitly in the minimal subtraction (MS) scheme to their form in the CW scheme. The Higgs mass can then be determined from the effective potential: the $LL$ result is $m_{H}=219\;GeV/c^2$ decreases to $m_{H}=188\;GeV/c^2$ at $N^{2}LL$ order and $m_{H}=163\;GeV/c^2$ at $N^{4}LL$ order. No reasonable estimate of $m_H$ can be made at orders $V_{NLL}$ or $V_{N^3LL}$. This is taken to be an indication that this mechanism for spontaneous symmetry breaking is in fact viable, though one in which there is slow convergence towards the actual value of $m_H$. The mass $163\;GeV/c^2$ is argued to be an upper bound on $m_H$.Comment: 24 pages, 5 figures. Updated version contains new discussion, references, figures, and corrects errors in reference

Potencial bacteriocinogênico de bactérias ácido lácticas e staphylococcaceae isoladas da microbiota de embutidos cárneos artesanais na região Sul/Brasil.

Projeto/Plano de Ação: 03.08.06.009

Alternative Chelator for 89Zr Radiopharmaceuticals: Radiolabeling and Evaluation of 3,4,3-(LI-1,2-HOPO)

Zirconium-89 is an effective radionuclide for antibody-based positron emission tomography (PET) imaging because its physical half-life (78.41 h) matches the biological half-life of IgG antibodies. Desferrioxamine (DFO) is currently the preferred chelator for 89Zr4+; however, accumulation of 89Zr in the bones of mice suggests that 89Zr4+ is released from DFO in vivo. An improved chelator for 89Zr4+ could eliminate the release of osteophilic 89Zr4+ and lead to a safer PET tracer with reduced background radiation dose. Herein, we present an octadentate chelator 3,4,3-(LI-1,2-HOPO) (or HOPO) as a potentially superior alternative to DFO. The HOPO ligand formed a 1:1 Zr-HOPO complex that was evaluated experimentally and theoretically. The stability of 89Zr-HOPO matched or surpassed that of 89Zr-DFO in every experiment. In healthy mice, 89Zr-HOPO cleared the body rapidly with no signs of demetalation. Ultimately, HOPO has the potential to replace DFO as the chelator of choice for 89Zr-based PET imaging agents

Obesity-dependent changes in interstitial ECM mechanics promote breast tumorigenesis.

Obesity and extracellular matrix (ECM) density are considered independent risk and prognostic factors for breast cancer. Whether they are functionally linked is uncertain. We investigated the hypothesis that obesity enhances local myofibroblast content in mammary adipose tissue and that these stromal changes increase malignant potential by enhancing interstitial ECM stiffness. Indeed, mammary fat of both diet- and genetically induced mouse models of obesity were enriched for myofibroblasts and stiffness-promoting ECM components. These differences were related to varied adipose stromal cell (ASC) characteristics because ASCs isolated from obese mice contained more myofibroblasts and deposited denser and stiffer ECMs relative to ASCs from lean control mice. Accordingly, decellularized matrices from obese ASCs stimulated mechanosignaling and thereby the malignant potential of breast cancer cells. Finally, the clinical relevance and translational potential of our findings were supported by analysis of patient specimens and the observation that caloric restriction in a mouse model reduces myofibroblast content in mammary fat. Collectively, these findings suggest that obesity-induced interstitial fibrosis promotes breast tumorigenesis by altering mammary ECM mechanics with important potential implications for anticancer therapies

Ire1α-Regulated Rate of mRNA Translation is Required for Acquisition of Identity and Polarity in Upper Layer Cortical Neurons

Evolutionary expansion of the neocortex is associated with the increase in upper layer neurons. Here, we present Inositol-Requiring Enzyme 1α, Ire1α, as an essential determinant of upper layer fate, neuronal polarization and cortical lamination. We demonstrate a non-canonical function of Ire1α in the regulation of global translation rates in the developing neocortex through its dynamic interaction with the ribosome and regulation of eIF4A1 and eEF-2 expression. Inactivation of Ire1α engenders lower protein synthesis rates associated with stalled ribosomes and decreased number of translation start sites. We show unique sensitivity of upper layer fate to translation rates. Whereas eEF-2 is required for cortical lamination, eIF4A1 regulates acquisition of upper layer fate downstream of Ire1α in a mechanism of translational control dependent on 5’UTR-embedded structural elements in fate determinant genes. Our data unveil developmental regulation of ribosome dynamics as post-transcriptional mechanisms orchestrating neuronal diversity establishment and assembly of cortical layers

The Path-Integral Approach to the N=2 Linear Sigma Model

In QFT the effective potential is an important tool to study symmetry breaking phenomena. It is known that, in some theories, the canonical approach and the path-integral approach yield different effective potentials. In this paper we investigate this for the Euclidean N=2 linear sigma model. Both the Green's functions and the effective potential will be computed in three different ways. The relative merits of the various approaches are discussed.Comment: 2 figure