1,219 research outputs found
Supersymmetry and Gravitational Quadrupoles
We derive model independent, non-perturbative supersymmetric sum rules for
the gravitational quadrupole moments of arbitrary-spin particles in any N=1
supersymmetric theory. These sum rules select a ``preferred'' value of h=1
where the ``h-factor'' is the gravitational quadrupole analog of the
gyromagnetic ratio or g-factor. This value of h=1 corresponds identically to
the preferred field theory value obtained by tree-level unitarity
considerations. The presently derived h-factor sum rule complements and
generalizes previous work on electromagnetic moments where g=2 was shown to be
preferred by both supersymmetric sum rule and tree-level unitarity arguments.Comment: 10 pages, plain Te
Pathogenesis of Acute Graft-Versus-Host Disease: Cytokines and Cellular Effectors
The pathogenesis of acute graft versus host disease (GVHD) is multistep process. This review considers acute GVHD in three sequential steps: conditioning regimen, donor T cell activation, and effector mechanisms. In step one, the conditioning regimen simultaneously damages and activates host tissues, amplifying antigen presentation to allogeneic donor T cells. In step two, donor T cells, activated by host alloantigens, proliferate and secrete a variety of cytokines. Type 1 cytokines (interleukin-2 and interferon-γ) are critical for acute GVHD, but several regulatory mechanisms of tissue damage include inflammatory cytokines and cytolytic cellular effectors. The gastrointestinal (GI) tract is a principal target organ because damage to the GI mucosa can release inflammatory mediators such as endotoxin that amplify systemic disease. The inflammatory processes of acute GVHD can be considered as a distortion of the cellular responses to viral and bacterial infections. Cell-mediated toxicity is critical to other GVHD target organs, particularly the liver, where Fas-mediated injury predominates. The cytolytic pathways (e.g., perforin) clearly intensify acute GVHD, although they are not necessary for systemic disease in several model systems. Many of these insights come from animal models using mutant mouse strains that can clarify the role of individual proteins or cell types in the disease process. These insights should allow the testing of new classes of drugs and inhibitors in clinical bone marrow transplantation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63129/1/15258160050079407.pd
Supersymmetric Sum Rules for Electromagnetic Multipoles
We derive model independent, non-perturbative supersymmetric sum rules for
the magnetic and electric multipole moments of any theory with N=1
supersymmetry. We find that in any irreducible N=1 supermultiplet the diagonal
matrix elements of the l-multipole moments are completely fixed in terms of
their off-diagonal matrix elements and the diagonal (l-1)-multipole moments.Comment: 10 pages, plain Te
Exploring potentialities of energy-connected buildings: Performance assessment of an innovative low-exergy design concept for a building heating supply system
Abstract Low exergy building systems generate new possibilities for the design of high performance buildings, especially when the design of a new building is considered as part of a district where the relationship between buildings are optimized to minimize the dispersion of energy in the environment and maximize the recovery of waste energy. We present an innovative design concept and the performance assessment of the heating system of the new Embodied Computation Laboratory at Princeton University. The system is demonstrated to be able to match the heat demand without need for backup systems
Running Gauge Couplings and Thresholds in the Type II Superstring
A distinctive feature of string unification is the possibility of unification
by a non-simply-laced group. This occurs most naturally in four dimensional
type~II string models where the gauge symmetry is realized by Kac-Moody
algebras at different levels. We investigate the running coupling constants and
the one-loop thresholds for such general models. As a specific case, we examine
a model and find that the threshold
corrections lead to a small increase in the unification scale.Comment: 12 pages, IFP-432-UN
The Escape of Ionizing Photons from OB Associations in Disk Galaxies: Radiation Transfer Through Superbubbles
By solving the time-dependent radiation transfer problem of stellar radiation
through evolving superbubbles within a smoothly varying HI distribution, we
estimate the fraction of ionizing photons emitted by OB associations that
escapes the HI disk of our Galaxy into the halo and intergalactic medium (IGM).
We consider both coeval star-formation and a Gaussian star-formation history
with a time spread sigma_t = 2 Myr. We consider both a uniform H I distribution
and a two-phase (cloud/intercloud) model, with a negligible filling factor of
hot gas. We find that the shells of the expanding superbubbles quickly trap or
attenuate the ionizing flux, so that most of the escaping radiation escapes
shortly after the formation of the superbubble. For the coeval star-formation
history, the total fraction of Lyman Continuum photons that escape both sides
of the disk in the solar vicinity is f_esc approx 0.15 +/- 0.05. For the
Gaussian star formation history, f_esc approx 0.06 +/- 0.03, a value roughly a
factor of two lower than the results of Dove & Shull (1994), where superbubbles
were not considered. For a local production rate of ionizing photons Psi_LyC =
4.95 X 10^7 cm^{-2} s^{-1}, the flux escaping the disk is Phi_LyC approx
(1.5-3.0) X 10^6 cm^{-2} s^{-1} for coeval and Gaussian star formation,
comparable to the flux required to sustain the Reynolds layer.Comment: Revised version (expanded), accepted for publication by ApJ, 38
pages, 8 figures, aasms4.sty and aabib.sty files include
Graft-versus-host disease of the skin: life and death on the epidermal edge
AbstractDespite impressive advances in the field of allogeneic hematopoietic transplantation, graft versus host disease (GVHD) remains a significant obstacle to be overcome; it would enhance the safety and efficacy of this life-saving therapy. This review provides a framework for understanding the molecular and cellular basis underlying GVHD. We propose a 3-phase model of GVHD that highlights the importance of the conditioning regimen on the recipient tissues administered prior to infusion of donor bone marrow inoculum. A novel skin explant model, designed to take into consideration the immunobiological consequences of conditioning regimens on resident host cells, is proposed to advance our understanding of GVHD and serve as a potential prognostic tool when allogeneic recipient/donor combinations are being contemplated in the clinic. Within this review, specific emphasis is placed on the importance of defining the apoptotic machinery engaged in epidermal keratinocytes triggered by both conditioning regimens, and by host resident and recruited immunocytes and soluble mediators produced at sites of injury. The review is completed with a working model for cutaneous GVHD. Although the skin is highlighted because of its accessibility for clinical observations and serial sampling opportunities, lessons learned from studies of cutaneous GVHD are likely to provide valuable insights into GVHD occurring in the gastrointestinal tract, lung, and liver. With new insights designed to better predict and prevent GVHD and novel agents designed to treat GVHD, overcoming this current impediment to successful bone marrow transplantation should become increasingly feasible
g=1 for Dirichlet 0-branes
Dirichlet 0-branes, considered as extreme Type IIA black holes with spin
carried by fermionic hair, are shown to have the anomalous gyromagnetic ratio
g=1, consistent with their interpretation as Kaluza-Klein modes.Comment: 13 pages, Late
What is the effect of a decision aid in potentially vulnerable parents? Insights from the head CT choice randomized trial.
ObjectiveTo test the hypotheses that use of the Head CT Choice decision aid would be similarly effective in all parent/patient dyads but parents with high (vs low) numeracy experience a greater increase in knowledge while those with low (vs high) health literacy experience a greater increase in trust.MethodsThis was a secondary analysis of a cluster randomized trial conducted at seven sites. One hundred seventy-two clinicians caring for 971 children at intermediate risk for clinically important traumatic brain injuries were randomized to shared decision making facilitated by the DA (n = 493) or to usual care (n = 478). We assessed for subgroup effects based on patient and parent characteristics, including socioeconomic status (health literacy, numeracy and income). We tested for interactions using regression models with indicators for arm assignment and study site.ResultsThe decision aid did not increase knowledge more in parents with high numeracy (P for interaction [Pint ] = 0.14) or physician trust more in parents with low health literacy (Pint = 0.34). The decision aid decreased decisional conflict more in non-white parents (decisional conflict scale, -8.14, 95% CI: -12.33 to -3.95; Pint = 0.05) and increased physician trust more in socioeconomically disadvantaged parents (trust in physician scale, OR: 8.59, 95% CI: 2.35-14.83; Pint = 0.04).ConclusionsUse of the Head CT Choice decision aid resulted in less decisional conflict in non-white parents and greater physician trust in socioeconomically disadvantaged parents. Decision aids may be particularly effective in potentially vulnerable parents
- …