A supersymmetric D-brane Model of Space-Time Foam

We present a supersymmetric model of space-time foam with two stacks of eight D8-branes with equal string tensions, separated by a single bulk dimension containing D0-brane particles that represent quantum fluctuations in the space-time foam. The ground state configuration with static D-branes has zero vacuum energy. However, gravitons and other closed-string states propagating through the bulk may interact with the D0-particles, causing them to recoil and the vacuum energy to become non zero. This provides a possible origin of dark energy. Recoil also distorts the background metric felt by energetic massless string states, which travel at less than the usual (low-energy) velocity of light. On the other hand, the propagation of chiral matter anchored on the D8 branes is not affected by such space-time foam effects.Comment: 33 pages, latex, five figure

Lymphatic expression of CLEVER-1 in breast cancer and its relationship with lymph node metastasis

BACKGROUND Mechanisms regulating breast cancer lymph node metastasis are unclear. Staining of CLEVER-1 (common lymphatic endothelial and vascular endothelial receptor-1) in human breast tumors was used, along with in vitro techniques, to assess involvement in the metastatic process. METHODS 148 sections of primary invasive breast cancers, with 10 yr follow-up, were stained with anti-CLEVER-1. Leukocyte infiltration was assessed, along with involvement of specific subpopulations by staining with CD83 (mature dendritic cells, mDC), CD209 (immature DC, iDC) and CD68 (macrophage, Mϕ). In vitro expression of CLEVER-1 on lymphatic (LEC) and blood endothelial cells (BEC) was examined by flow cytometry. RESULTS In vitro results showed that although both endothelial cell types express CLEVER-1, surface expression was only evident on LEC. In tumour sections CLEVER-1 was expressed in blood vessels (BV, 61.4% of samples), lymphatic vessels (LV, 18.2% of samples) and in Mϕ/DCs (82.4% of samples). However, only CLEVER-1 expression in LV was associated with LN metastasis (p = 0.027) and with Mϕ indices (p = 0.021). Although LV CLEVER-1 was associated with LN positivity there was no significant correlation with recurrence or overall survival, BV CLEVER-1 expression was, however, associated with increased risk of recurrence (p = 0.049). The density of inflammatory infiltrate correlated with CLEVER-1 expression in BV (p < 0.001) and LV (p = 0.004). CONCLUSIONS The associations between CLEVER-1 expression on endothelial vessels and macrophage/leukocyte infiltration is suggestive of its regulation by inflammatory conditions in breast cancer, most likely by macrophage-associated cytokines. Its upregulation on LV, related surface expression, and association with LN metastasis suggest that it may be an important mediator of tumor cell metastasis to LN

Out of Autoclave Metal and FRP Composites Thermo-Hydroforming

In this chapter, we explore a novel type of thermo-hydroforming process conceived to expand the role of sheet metal hydroforming machines from one of just forming sheet metal materials into one of being able to form multiple materials. This work specifically focuses on the use of thermohydroforming to shape and thermal catalyze prepreg composite sheets into rigid parts of complex 3D geometry. Elastomeric Sheet Hydroforming is an excellent low-cost manufacturing method requiring a single tool die on only one side. The mating die is a flexible membrane backed by fluid under high pressure. Various designs configurations exist that allow for significant pressure levels of up to 1400 Bar (20,000 psi), to be contained. The cycle life of the containment vessel components is commonly designed to accommodate up to 1 million cycles of use over 40 years. However, these machines can be expensive ranging in cost from several hundred thousand up to $6 million dollars. Expanding the market scope and potential of the press by enabling them to also form composites will provide benefit to both the machine owners and their customers. The intent of this project is to advance the state of the art in composites forming by demonstrating through FEA modeling that a hydroforming machine can be potentially configured to form thermally catalyzed prepreg composite panels. It is believed that the concept in like manner, will also be applicable to forming metal-composite hybrid panels, stratified metal thermoplastic laminates, thermoplastic synthetic granites and of course sheet metal materials. This concept seeks to benefit the American Manufacturing Industry and create jobs in the U.S. by providing a low-cost method for manufacturers to produce medium to very large sized high-quality sheet composite parts of an advanced nature in construction. This application is for operations requiring volumes less than 30,000 forming cycles per year per machine. Processes currently exist in the industry that utilizes heated air or heated glycol to form sheet materials. However, this process seeks to offer greater benefit by using pure water as a high thermal conductivity working fluid in a scheme that offers vastly elevated pressure during forming and curing cycles

Sustainable and Efficient Hydroforming of Aerospace Composite Structures

Hydroforming, in comparison with sheet stamping, is an efficient and economical manufacturing process for complex-shape aerospace composite parts because it does not require the use of a female die. The hydroforming manufacturing method is expected to greatly increase the formability of composite parts by using a controllable heated and pressurized fluid that acts as a support for the composite sheet throughout the forming process. The design of a hydroforming process and a machine to shape complex aerospace composite parts is proposed in this chapter. The design and analysis of a sheet metal hydroforming machine with composite overwrap are presented to sustainably and efficiently produce not only the aerospace composites but also dual-phase and bake hardened steel parts with complex 3D geometry

Mortality risk and social network position in southern resident killer whales (Orcinus orca): sex differences and the importance of salmon abundance

An individual\u27s ecological environment affects its mortality risk, which in turn has fundamental consequences for life-history evolution and population viability. In many species, social relationships are likely to be an important component of an individual\u27s environment, and therefore mortality risk. Here, we examine the relationship between social position and mortality risk in Southern resident killer whales (Orcinus orca) using over three decades of social and demographic data. We find that the social position of male, but not female, killer whales in their social unit predicts their mortality risk. More socially integrated males have a significantly lower risk of mortality than socially peripheral males, particularly in years of low salmon abundance, suggesting that social position mediates access to resources. Male killer whales are larger and require more resources than females, increasing their vulnerability to starvation in years of low salmon abundance. More socially integrated males are likely to have better access to social information and food-sharing opportunities which may enhance their survival in years of low prey abundance. Our results show that observable variation in the social environment is linked to variation in mortality risk. Furthermore, our results highlight the importance of considering sex differences in social effects on survival when developing conservation strategies for long-lived social mammals

Standard methods for Apis mellifera anatomy and dissection

An understanding of the anatomy and functions of internal and external structures is fundamental to many studies on the honey bee Apis mellifera. Similarly, proficiency in dissection techniques is vital for many more complex procedures. In this paper, which is a prelude to the other papers of the COLOSS BEEBOOK, we outline basic honey bee anatomy and basic dissection techniques

Self-similar Bianchi type VIII and IX models

It is shown that in transitively self-similar spatially homogeneous tilted perfect fluid models the symmetry vector is not normal to the surfaces of spatial homogeneity. A direct consequence of this result is that there are no self-similar Bianchi VIII and IX tilted perfect fluid models. Furthermore the most general Bianchi VIII and IX spacetime which admit a four dimensional group of homotheties is given.Comment: 5 pages, Latex; One reference and minor clarifications added. To appear in General Relativity and Gravitatio