\u3cem\u3eAgent Orange\u3c/em\u3e and the Government Contract Defense: Are Military Manufacturers Immune from Products Liability?

Courts are unwilling to impose products liability on government contractors, particularly during wartime. If a contractor nonnegligently performs a government contract according to specifications provided by the government, then it will be absolved from liability to third parties. This Comment discusses the elements of, and prudential justifications for, this government contract defense. After examining the relationship between the government contract defense and the doctrine of sovereign immunity, the Comment concludes that the defense is necessary to preserve the government\u27s discretionary authority over military procurement

R-symmetric Gauge Mediation and the MRSSM

This is an invited summary of a seminar talk given at various institutions in the United States and Canada. After a brief introduction, a review of the minimal R-symmetric supersymmetric standard model is given, and the benefits to the flavor sector are discussed. R-symmetric gauge mediation is an attempt to realize this model using metastable supersymmetry breaking techniques. Sample low energy spectra are presented and tuning is discussed. Various other phenomenological results are summarized.Comment: 14 pages, invited Brief Review, submitted to Modern Physics Letters A; v2: replaced Figure 1, updated acknowledgments, fixed typo

CONVERGENCE OF SIGNALING BY INTERLEUKIN-3, GRANULOCYTE-MACROPHAGE COLONY-STIMULATING FACTOR, AND MAST CELL GROWTH FACTOR ON JAK2 TYROSINE KINASE

Mast cell growth factor (MGF) (also called stem cell factor) synergizes with several lymphokines, including interleukin-3 (IL-3) and granulocyte-macrophage colony-stimulating factor (GM-CSF), to promote proliferation and differentiation of certain hemopoietic progenitor cells. Although similar patterns of tyrosine-phosphorylated proteins characterize cells stimulated by MGF, IL-3, and GM-CSF, only the MGF receptor is a tyrosine kinase, and the heterodimeric receptors for IL-3 and GM-CSF share a common beta subunit that is devoid of enzymatic activity. Here we show that signaling pathways utilized by all three cytokines include the cytoplasmic tyrosine kinase JAK2. Analysis of several factor-dependent myeloid cell lines indicated that JAK2 is physically associated with the common beta subunit and with MGF receptor (c-Kit) even prior to ligand binding. However, each of the ligands induced elevated tyrosine phosphorylation of JAK2 and a consequent increase in its catalytic activity. These results demonstrate for the first time the convergence within the same myeloid cells of signaling pathways originating in two distinct lymphokine receptors and a tyrosine kinase receptor on activation of a cytoplasmic tyrosine kinase

R-symmetric gauge mediation

We present a version of Gauge Mediated Supersymmetry Breaking which preserves an R-symmetry - the gauginos are Dirac particles, the A-terms are zero, and there are four Higgs doublets. This offers an alternative way for gauginos to acquire mass in the supersymmetry-breaking models of Intriligator, Seiberg, and Shih. We investigate the possibility of using R-symmetric gauge mediation to realize the spectrum and large sfermion mixing of the model of Kribs, Poppitz, and Weiner.Comment: 26+ pages, 3 figures, BIBTEX; v2 published version: references added, paragraph on spectrum running removed, section added on adjoint scalar masses, clarification of the meaning of Table 3 adde

Searching for super-WIMPs in leptonic heavy meson decays

We study constraints on the models of bosonic super-weakly interacting particle (super-WIMP) dark matter (DM) with DM masses $m_X \sim \mathcal{O}(1 - 100)$ keV from leptonic decays $M\rightarrow \ell \bar{\nu}_\ell + X$, where $M=B^\pm, D^\pm, D_s^\pm$ is a heavy meson state. We focus on two cases where $X$ denotes either a light pseudoscalar (axion-like), or a light vector state that couples to the standard model (SM) through kinetic mixing. We note that for a small DM mass these decays are separately sensitive to DM couplings to quarks, but not its mass.Comment: 17 pages, 3 figures, 6 table

Nuclear Punctate Distribution of ALL-1 is Conferred by Distinct Elements at the N-terminus of the Protein

The ALL-1 gene positioned at 11q23 is directly involved in human acute leukemia either through a variety of chromosome translocations or by partial tandem duplications. ALL-1 is the human homologue of Drosophila trithorax which plays a critical role in maintaining proper spatial and temporal expression of the Antennapedia-bithorax homeotic genes determining the fruit fly's body pattern. Utilizing specific antibodies, we found that the ALL-1 protein distributes in cultured cells in a nuclear punctate pattern. Several chimeric ALL-1 proteins encoded by products of the chromosome translocations and expressed in transfected cells showed similar speckles. Dissection of the ALL-1 protein identified within its -1,100 N-terminal residues three polypeptides directing nuclear localization and at least two main domains conferring distribution in dots. The latter spanned two short sequences conserved with TRITHORAX. Enforced nuclear expression of other domains of ALL-1, such as the PHD (zinc) fingers and the SET motif, resulted in uniform nonpunctate patterns. This indicates that positioning of the ALL-1 protein in subnuclear structures is mediated via interactions of ALL-1 N-terminal elements. We suggest that the speckles represent protein complexes which contain multiple copies of the ALL-1 protein and are positioned at ALL-1 target sites on the chromatin. Therefore, the role of the N-terminal portion of ALL-1 is to direct the protein to its target genes

Threshold effects in excited charmed baryon decays

Motivated by recent results on charmed baryons from CLEO and FOCUS, we reexamine the couplings of the orbitally excited charmed baryons. Due to its proximity to the [Sigma_c pi] threshold, the strong decays of the Lambda_c(2593) are sensitive to finite width effects. This distorts the shape of the invariant mass spectrum in Lambda_{c1}-> Lambda_c pi^+pi^- from a simple Breit-Wigner resonance, which has implications for the experimental extraction of the Lambda_c(2593) mass and couplings. We perform a fit to unpublished CLEO data which gives M(Lambda_c(2593)) - M(Lambda_c) = 305.6 +- 0.3 MeV and h2^2 = 0.24^{+0.23}_{-0.11}, with h2 the Lambda_{c1}-> Sigma_c pi strong coupling in the chiral Lagrangian. We also comment on the new orbitally excited states recently observed by CLEO.Comment: 9 pages, 3 figure

Two-loop RGEs with Dirac gaugino masses

The set of renormalisation group equations to two loop order for general supersymmetric theories broken by soft and supersoft operators is completed. As an example, the explicit expressions for the RGEs in a Dirac gaugino extension of the (N)MSSM are presented.Comment: 10 pages + 24 pages of RGEs in appendix; no figure

DN interaction from meson exchange

A model of the DN interaction is presented which is developed in close analogy to the meson-exchange KbarN potential of the Juelich group utilizing SU(4) symmetry constraints. The main ingredients of the interaction are provided by vector meson (rho, omega) exchange and higher-order box diagrams involving D*N, D\Delta, and D*\Delta intermediate states. The coupling of DN to the pi-Lambda_c and pi-Sigma_c channels is taken into account. The interaction model generates the Lambda_c(2595) resonance dynamically as a DN quasi-bound state. Results for DN total and differential cross sections are presented and compared with predictions of an interaction model that is based on the leading-order Weinberg-Tomozawa term. Some features of the Lambda_c(2595) resonance are discussed and the role of the near-by pi-Sigma_c threshold is emphasized. Selected predictions of the orginal KbarN model are reported too. Specifically, it is pointed out that the model generates two poles in the partial wave corresponding to the Lambda(1405) resonance.Comment: 14 pages, 8 figure

Overview of the Role for Calreticulin in the Enhancement of Wound Healing through Multiple Biological Effects

Calreticulin (CRT), an intracellular chaperone protein crucial for the proper folding and transport of proteins through the endoplasmic reticulum, has more recent acclaim as a critical regulator of extracellular functions, particularly in mediating cellular migration and as a requirement for phagocytosis of apoptotic cells. Consistent with these functions, we show that the topical application of CRT has profound effects on the process of wound healing by causing a dose-dependent increase in epithelial migration and granulation tissue formation in both murine and porcine normal and impaired animal models of skin injury. These effects of CRT are substantiated, in vitro, as we show that CRT strongly induces cell migration/wound closure of human keratinocytes and fibroblasts, using a wound/scratch plate assay, and stimulates cellular proliferation of human keratinocytes, fibroblasts, and vascular endothelial cells, providing mechanistic insight into how CRT functions in repair. Similarly, in both animal models, the histology of the wounds show marked proliferation of basal keratinocytes and dermal fibroblasts, dense cellularity of the dermis with notably increased numbers of macrophages and well-organized collagen fibril deposition. Thus, CRT profoundly affects the wound healing process by recruiting cells essential for repair into the wound, stimulating cell growth, and increasing extracellular matrix production