Structural load challenges during space shuttle development

The challenges that resulted from the unique configuration of the space shuttle and capabilities developed to meet these challenges are described. The methods and the organization that were developed to perform dynamic loads analyses on the space shuttle configuration and to assess dynamic data developed after design are discussed. Examples are presented from the dynamic loads analysis of the lift-off and maximum dynamic pressure portion of ascent. Also shown are orbital flight test results, for which selected predicted responses are compared to measured data for the lift-off and high-dynamic-pressure times of ascent. These results have generally verified the design analysis. However, subscale testing was found to be deficient in predicting full-scale results in two areas: the ignition overpressure at lift-off and the aerodynamics/plume interactions at high-q boost. In these areas, the results of the flight test program were accommodated with no impact to the vehicle design

Beads for Cell Immobilization: Comparison of Alternative Additive Manufacturing Techniques

The attachment or entrapment of microbial cells and enzymes are promising solutions for various industrial applications. When the traps are beads, they are dispersed in a fluidized bed in a vessel where a pump guarantees fresh liquid inflow and waste outflow without washing out the cells. Scientific papers report numerous types of cell entrapment, but most of their applications remain at the laboratory level. In the present research, rigid polymer beads were manufactured by two different additive manufacturing (AM) techniques in order to verify the economy, reusability, and stability of the traps, with a view toward a straightforward industrial application. The proposed solutions allowed for overcoming some of the drawbacks of traditional manufacturing solutions, such as the limited mechanical stability of gel traps, and they guaranteed the possibility of producing parts of constant quality with purposely designed exchange surfaces, which are unfeasible when using conventional processes. AM proved to be a viable manufacturing solution for beads with complex shapes of two different size ranges. A deep insight into the production and characteristics of beads manufactured by AM is provided. The paper provides biotechnologists with a manufacturing perspective, and the results can be directly applied to transit from the laboratory to the industrial scale

The Lightest Pseudo-Goldstone Boson at Future e+e- Colliders

In a class of models of dynamical symmetry breaking not ruled out by the available data, the lightest neutral pseudo-Nambu-Goldstone boson P0 contains only down-type techniquarks and charged technileptons. Its mass scale is naturally determined by the b-quark and therefore it is likely to be light. As the presence of pseudo-Nambu-Goldstone bosons in models of dynamical symmetry breaking is a quite general feature, the search of the P0 at colliders is an interesting opportunity of putting limits on or discovering a dynamical electroweak symmetry breaking scenario. In this note we discuss the prospects for discovering and studying the P0 at future e+e- and gamma-gamma colliders.Comment: 15 pages, 8 figures, LaTeX (epsfig), Proceedings of the Second ECFA/DESY Study on Physics Studies for a Future Linear Collide

Conditions for transient epidemics of waterborne disease in spatially explicit systems

Waterborne diseases are a diverse family of infections transmitted through ingestion of-or contact with-water infested with pathogens. Outbreaks of waterborne infections often show well-defined spatial signatures that are typically linked to local eco-epidemiological conditions, water-mediated pathogen transport and human mobility. In this work, we apply a spatially explicit network model describing the transmission cycle of waterborne pathogens to determine invasion conditions in metacommunities endowed with a realistic spatial structure. Specifically, we aim to define conditions under which pathogens can temporarily colonize a set of human communities, thus triggering a transient epidemic outbreak. To that end, we apply generalized reactivity analysis, a recently developed methodological framework for the study of transient dynamics in ecological systems subject to external perturbations. The study of pathogen invasion is complemented by the detection of the spatial signatures associated with the perturbations to a disease-free system that are expected to be amplified the most over different time scales. Understanding the drivers of waterborne disease dynamics over time scales that are relevant to epidemic and/or endemic transmission is a crucial, cross-disciplinary challenge, as large portions of the developing world still struggle to cope with the burden of these infections

A New Technique for Determining the Properties of a Narrow ss-channel Resonance at a Muon Collider

We explore an alternative to the usual procedure of scanning for determining the properties of a narrow $s$-channel resonance. By varying the beam energy resolution while sitting on the resonance peak, the width and branching ratios of the resonance can be determined. The statistical accuracy achieved is superior to that of the usual scan procedure in the case of a light SM-like Higgs boson with \mh>130\gev or for the lightest pseudogoldstone boson of a strong electroweak breaking model if \mpzero>150\gev.Comment: 4 pages, 1 figur

Investigation of TiCr Hydrogen Storage Alloy

A new reversible hydrogen storage material, based on TiCr metal alloy, is proposed. Cr and Ti were mixed and melted in a final atomic ratio of 1,78. Chemical-physical characterisations, in terms of XRD and SEM-EDX, were performed. The quantification of Laves phases was performed through Rietveld refinements. The atomic Cr/Ti ratio was determined by EDX analysis and 1,71 was obtained. The H2 sorption/desorption measurements by Sievert apparatus were carried out. After different tests varying temperature and pressure, a protocol measurement was established; and a H2 sorption value of 0,4 wt% at 200 °C/10 bar with a fast kinetic at 5 bar (Dwt% of about 0,3 wt%) were obtained. Hydrogen desorption measurements performed in the same conditions of T confirmed a totally reversible trend. A confirm of metal hydride formation was recorded by XRD, in fact, comparing X-Ray patterns before and after volumetric tests a notable difference was recorded

Pseudo Goldstones at Future Colliders from the Extended Bess Model

We consider the production of the lightest pseudo-Goldstone bosons at future colliders through the vector resonances predicted by the extended BESS model, which consists of an effective lagrangian parametrization with dynamical symmetry breaking, describing scalar, vector and axial-vector bound states in a rather general framework. We find that the detection of pseudo-Goldstone pairs at LHC requires a careful evaluation of backgrounds. For e+e- collisions in the TeV range the backgrounds can be easily reduced and the detection of pseudo-Goldstone pairs is generally easier.Comment: 17 pages and 12 figures (included as a uuencoded tar file), LaTeX (style article), UGVA-DPT 1994/03-84

Low-energy theorems of QCD and bulk viscosity at finite temperature and baryon density in a magnetic field

The nonperturbative QCD vacuum at finite temperature and a finite baryon density in an external magnetic field is studied. Equations relating nonperturbative condensates to the thermodynamic pressure for $T\neq 0$, $\mu_q \neq 0$ and $H\neq 0$ are obtained, and low-energy theorems are derived. A bulk viscosity $\zeta(T, \mu, H)$ is expressed in terms of basic thermodynamical quantities describing the quark-gluon matter at $T\neq 0$, $\mu_q \neq 0$, and $H\neq 0$. Various limiting cases are also considered.Comment: 12 pages; v2: title changed, new section about bulk viscosity and new references added; v3: new discussion adde

H-Content Is Not Predictive of Perfluorocarbon Ocular Endotamponade Cytotoxicity in Vitro

In recent years, cases of retinal toxicity occurred in some European, Middle Eastern, and South American countries following the use of perfluorocarbon liquids (PFCLs) on vitreoretinal surgeries owing to impurities in the product. Moreover, Spanish ophthalmologists reported several toxic cases on the use of perfluoro-n-octane Ala Octa (Alamedics, Dornstadt, Germany), raising the necessity of reviewing the current validated methods used for assessing the safety of PFCLs. We proved that in samples of PFCLs contaminated on purpose with impurities previously detected in Ala Octa devices, the determination of the so-called H-content using a 1H NMR quantitative assay implemented with the electronic reference to access in vivo concentrations 2 technology failed to demonstrate a correlation between the H-content and in vitro cytotoxicity test in ARPE-19 and BALB 3T3 cell lines. Therefore, direct information on the safety of PFCLs was provided only by the cytotoxicity test in vitro validated according to ISO 10993-5, and the H-content was not predictive of perfluorocarbon ocular endotamponade cytotoxicity in vitr