3D printed components for quantum devices

Since the first demonstrations of laser cooling of atomic vapors in the late 1970s, the field of ultracold atoms has seen rapid advancements in the preparation, control and measurement of atomic gases. Ultra-cold atomic systems, either as individual atoms or in larger ensembles, provide a powerful tool for experimenters. Their large deBroglie wavelengths make them particularly useful for interferometric applications, and their isotropic properties when unperturbed make them ideal candidates for frequency standards. A recent drive has seen experimenters looking to develop scalable, portable and robust atomic systems as a metrological tool outside of the typical laboratory environment. This could see unprecedented sensitivities made available for areas as diverse as GPS-free navigation, biomedical imaging and non-invasive underground mapping. Over the course of this thesis we explore additive manufacturing (3D printing) as a production technique for quantum technology. 3D-printing offers unrivalled design freedom and rapid prototyping, allowing us to develop a number of printed structures to test the viability of selective laser melting as a technique to produce metallic components that survive within, and also hold, the ultra-high vacuum environment necessary for ultracold physics. The technique has the potential to improve the efficiency and compactness of devices. We begin first by printing an Al-Si-Mg vacuum flange, which is then solution heat treated in post processing and milled to have a standard vacuum-sealing knife edge on its surface. By installing the flange on a test vacuum set-up, baking out over a week at 200­­­°C and pumping down, a pressure of 10⁻¹¹ mbar is achieved. In the same material, a conductive structure called the cylinder trap is printed as a proof of concept ultracold atom source producing the fields necessary for a magneto-optical trap. A complete cold atom experiment is constructed to test the device, including a simple microcontroller-based control system. Dissipating as little as 20mW electrical power, the atom trap generates 10⁸ atoms with an average temperature on the order of (20.1 ± 0.2)μK, whilst having no measurable effect on the vacuum pressure, measured as < 10⁻¹⁰ mbar. A next-generation device is then investigated, building on the work of the cylinder trap and consideration of contemporary work on cold-atom sources. This device would output an even colder source of atoms, with a tapered design to both act as a differential pump and for atom compression for transport to a secondary trap. With calculations on optimal trapping regimes, an Ioffe-Pritchard style magnetic trap layout is created to efficiently capture atoms from the magnetooptical trap. Atoms would then be transported through a three-dimensional funnel structure into a secondary magnetic trap where fast, evaporative cooling could occur. Simultaneously the next thermal cloud can be captured to improve the average cycle time. Encouraged by collaborative work on a additively manufactured chamber, called the coral trap, a prototype design is developed and presented consisting of the funnel structure split across a multi-chamber printed architecture

Camus, Existentialism, and the Absurdity of Tyler Durden

In this paper, I make an argument that Albert Camus was not an existentialist despite the common stance that he was. I then examine Tyler Durden of David Fincher\u27s Fight Club to show what an absurd hero looks like

How Can We Do Better? Improving Performance in Global Textile and Apparel Supply Chains

In apparel manufacturing facilities in developing countries, experts can often be observed conducting time studies on sewing specialists, with the goal of increasing productivity by decreasing cycle times. Many companies in developing countries are attempting to increase performance by concentrating on productivity improvements (Bheda, 2002; Bheda, 2003; Joint Apparel Association Forum, 2007)

The effect of reactive nitrogen intermediates on Leishmania mexicana mexicana

Leishmania mexicana mexicana is a protozoan parasite that causes local and diffuse cutaneous leishmaniasis. There are no effective current vaccines, and current drugs have serious side effects. There is a wealth of evidence, both in vitro and in vivo, to suggest that the protective murine immune response involves the production of a set of partially oxidised products of nitrogen called Reactive Nitrogen Intermediates (RNI). RNI are synthesised during a protective murine immune response by the enzyme inducible Nitric Oxide Synthase (iNOS) and are extremely diverse both in their possible chemical targets and in their biological effects. Inhibition of RNI production in murine cutaneous leishmaniasis allows the parasite to survive in normally resistant hosts, and it is believed that they are the final effector mechanism in the protective Thl-type immune response. Very little was known about the targets of RNI in Leishmania. This thesis aims to investigate the processes by which RNI kill L. m. mexicana. This species was chosen because it has recently become possible to grow it as amastigotes axenically in vitro. [3H]- thymidine uptake and transformation efficiency viability assays were optimised for use with these axenic amastigotes. In addition, because of the unusual culture conditions for amastigotes - Schneider's Drosophila Medium, pH 5.5, with 20% (v/v) foetal calf serum - it was necessary to develop suitable methods for RNI production and detection. Production of RNI by S-nitroso-N-acetyl penicillamine and by acidified nitrite was used. Little work has been done on the role of RNI in the immune response to L. m. mexicana. Therefore, the susceptibility of this species to RNI produced by murine macrophages was determined. The kinetics of toxicity in axenic culture showed that RNI were cytotoxic rather than cytostatic to this species, and that RNI can take up to several hours to kill the parasite. RNI did not affect, and were not affected by various other components of the macrophage defence mechanism, namely beta-glucuronidase, cathepsin D and hydrogen peroxide. L. m. mexicana amastigotes were shown not to be particularly resistant to RNI compared to promastigotes, Escherichia coli, and the murine macrophage cell line J774. Low levels of RNI were also shown to be insufficient to induce a resistant phenotype in the parasite. There have been many suggestions of the possible antileishmanial targets of RNI, based on the action of RNI in other cell types. These include inhibition of the mitochondrial electron transport chain and other iron-containing proteins, damage to lipids, damage to DNA, damage of membrane components held on to the membrane by glycosyl-phosphatidylinositol (GPI) anchors, and inhibition of proteins that contain sulphydryl groups or tyrosine residues. The effect of RNI on the GPI-anchored glycoinositolphospholipids (GIPLs), DNA and mitochondrion of L. m. mexicana was examined. Of these, only the mitochondrion was affected by RNI at concentrations which approximated to the toxic concentrations, though DNA and GIPLs could be damaged by much higher concentrations of RNI. Inhibition of the mitochondrion was sufficient to account for all the toxicity of RNI to the parasite, since uncoupling the mitochondrial membrane with 2,4-dinitrophenol (DNP) caused similar kinetics of toxicity to RNI. It was also possible to inhibit the DNase activity of serum, and the implications of this to other biological systems are discussed. The involvement of the mitochondrion in the toxicity of RNI to amastigotes is not surprising given the evolutionary conservation of the enzymes in the mitochondrial electron transport chain, and given the involvement of these enzymes in RNI toxicity to E. coli and mammalian cells. However, since L. m. mexicana normally reside in low oxygen tensions, one might have expected that they would not be so reliant on their mitochondrion