Research study on materials processing in space Skylab experiment M553 - sphere forming

A research program was conducted to study the solidification of metals in the form of small spheres both in the one gravity environment of the earth laboratory and the low gravity environment of KC-135 trajectory flights and the Skylab 1/2 mission. The program had three phases. The details of the results of this program are contained in interim reports prepared at the conclusion of each of the three phases. This final report is intended to summarize the efforts and results described in detail in each of these interim reports, with particular emphasis on the differences observed between the ground-based and Skylab flight specimens

Teaching a New Dog Old Tricks: Resurrecting Multilingual Retrieval Using Zero-shot Learning

While billions of non-English speaking users rely on search engines every day, the problem of ad-hoc information retrieval is rarely studied for non-English languages. This is primarily due to a lack of data set that are suitable to train ranking algorithms. In this paper, we tackle the lack of data by leveraging pre-trained multilingual language models to transfer a retrieval system trained on English collections to non-English queries and documents. Our model is evaluated in a zero-shot setting, meaning that we use them to predict relevance scores for query-document pairs in languages never seen during training. Our results show that the proposed approach can significantly outperform unsupervised retrieval techniques for Arabic, Chinese Mandarin, and Spanish. We also show that augmenting the English training collection with some examples from the target language can sometimes improve performance.Comment: ECIR 2020 (short

IIaO ultraviolet and nuclear emulsion films responses to orbital flights on STS-3, STS-7, STS-8, and STS-40

Two types of film were flown on STS-40 space shuttle mission in June 1991. The IIaO special purpose ultraviolet film showed continued desensitization because of various thermal and cosmic ray interactions. The films were exposed to the space orbital environment for 9 days. There were several built-in launch pad delays of the shuttle mission. However, there was adequate monitoring of the temperature variations on board the shuttle that allowed for adequate knowledge of the thermal film history. This IIaO film was flown on the ASTRO I mission and is currently slated for use with the ASTRO II mission. A 50 micron thick IIIford Nuclear emulsion film was also placed on a 175 micron polyester base. The exposure to space produced several cosmic ray interactions that were analyzed and measured using Digital Image Processing techniques. This same nuclear emulsion film was flown on STS-8 and produced a similar number of cosmic ray and thermal interactions. From previous experiments of film using various laboratory electromagnetic radiation sources (e.g., alpha, beta, and neutron particles), we have been able to infer the possible oribtal interactions of both IIaO and nuclear emulsion films. The characteristic responses of IIaO on STS-40 compared favorably to the results obtained from previous STS-7 and STS-8 gas can experiments. The results indicate sufficient evidence correlating increased density on the film with possible cosmic ray, thermal and shuttle out gassing interactions

Studentsâ Clinical Learning in an Emerging Dental School: An Investigation in International Collaboration Between Michigan and Ghana

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/153593/1/jddj0022033720137712tb05644x.pd

Assembly of Molybdenum/Titanium μ-Oxo Complexes via Radical Alkoxide C−O Cleavage

Three-coordinate Ti(NRAr)_3 [R = C(CD_3)_2(CH_3), Ar = C_6H_3Me_2] was prepared in 73% yield by sodium amalgam reduction of ClTi(NRAr)_3 and in 83% yield upon treatment of TiCl_3(THF)_3 with 3 equiv of Li(NRAr)(OEt_2) in the presence of TMEDA. Ti(^tBuNPh)_3 was prepared similarly in 75% yield by treatment of TiCl_3(THF)_3 with 3 equiv of Li(^tBuNPh)(OEt_2) in the presence of TMEDA. Reaction of Ti(NRAr)_3 with NMo(O^tBu)_3 in hydrocarbon solvents at −35 °C generates a thermally unstable intermediate formulated as (^tBuO)_3Mo[μ-N]Ti(NRAr)_3, which readily loses a tert-butyl radical and isomerizes at 25 °C. Kinetics of the latter process were obtained over the temperature range 20−60 °C; the process exhibits clean first-order behavior. The following activation parameters were obtained:  ΔH⧧ = 21.4 ± 0.2 kcal mol^(-1) and ΔS⧧ = −3.7 ± 0.6 cal mol^(-1) K^(-1). The oxo-bridged product (^tBuO)_2(N)Mo[μ-O]Ti(NRAr)_3 was isolated in 83% yield from this reaction. Full characterization of the latter diamagnetic complex included an X-ray crystal structure and an ^(15)N NMR study. Ti(NRAr)_3 (1 equiv) reacts further with (^tBuO)_2(N)Mo[μ-O]Ti(NRAr)_3 to generate a species formulated as a second paramagnetic nitrido-bridged intermediate, (^tBuO)_2Mo{[μ-O]Ti(NRAr)_3}{[μ-N]Ti(NRAr)_3}, which at 25 °C loses a tert-butyl radical and isomerizes to give the final product, (^tBuO)(N)Mo{[μ-O]Ti(NRAr)_3}_2, isolated as an orange powder in 91% yield. Characterization of the latter diamagnetic complex included an ^(15)N NMR study. Attempts to displace a third tert-butyl radical by treatment of (^tBuO)(N)Mo{[μ-O]Ti(NRAr)_3}_2 with Ti(NRAr)_3 led to no reaction. Treatment of (^tBuO)(N)Mo{[μ-O]Ti(NRAr)_3}_2 with neat methyl iodide led to the isolation of (MeO)(N)Mo{[μ-O]Ti(NRAr)_3}_2 in 51% yield; ^(13)C and nitrido-^(15)N derivatives of this species were prepared for spectroscopic characterization. O_2Mo{[μ-O]Ti(^tBuNPh)_3}_2 was prepared in 59% yield upon treatment of MoO_2(O^tBu)_2 with 2 equiv of Ti(^tBuNPh)_3 in benzene at 65 °C. Full characterization of O_2Mo{[μ-O]Ti(^tBuNPh)_3}_2 included a single-crystal X-ray diffraction study. Previously reported (^iPrO)_3V[μ-O]Ti(NRAr)_3 was oxidized with ferrocenium triflate to give TfOTi(NRAr)_3 and OV(O^iPr)_3. TfOTi(NRAr)_3 was prepared independently in 80% yield by treatment of Ti(NRAr)_3 with ferrocenium triflate. (^iPrO)_3V[μ-O]Ti(NRAr)_3 is stable in the presence of methyl iodide. ITi(NRAr)_3 was prepared independently by treatment of Ti(NRAr)_3 with the stoichiometric amount of iodine. Paramagnetic (^tBuO)_3V[μ-O]Ti(NRAr)_3 was prepared as orange-brown needles in 94% yield and was found to be thermally stable. The relatively robust μ-nitrido compound (Me_2N)_3Mo[μ-N]Ti(^tBuNPh)_3, which was prepared in 77% isolated yield, showed no decomposition when heated in benzene at 70 °C for 13 h

Long discontinuous carbon fibre/polypropylene composites for high volume structural applications

A processing route is presented to manufacture discontinuous carbon fibre reinforced polypropylene (CF.PP) composites, using much longer fibre lengths (25mm) and higher volume fractions (up to 45%) than previously reported in the literature. Carbon fibre tows are coated with different ratios of polypropylene, blended with a maleic anhydride coupling agent, to investigate the influence of the interfacial shear strength at the microscale on the macroscale composite properties. Improvements in the tensile performance at the macroscale (70% increase) are not as high as those reported for the interfacial shear strength at the microscale (300%), following the addition of the coupling agent. Consequently, the tensile strength of the CF.PP material is only 45% of values reported for carbon fibre/epoxy systems, however, the tensile stiffness is comparable. This demonstrates the potential for using CF.PP for structural applications, following further process optimisation to overcome the current high levels of porosity (3.3% at 0.45Vf) to improve the tensile strength

The Effects of Accretion Luminosity upon Fragmentation in the Early Universe

We introduce a prescription for the luminosity from accreting protostars into smoothed particle hydrodynamics simulation, and apply the method to simulations of five primordial minihalos generated from cosmological initial conditions. We find that accretion luminosity delays fragmentation within the halos, but does not prevent it. In halos that slowly form a low number of protostars, the accretion luminosity can reduce the number of fragments that are formed before the protostars start ionising their surroundings. However, halos that rapidly form many protostars become dominated by dynamical processes, and the effect of accretion luminosity becomes negligible. Generally the fragmentation found in the halos is highly dependent on the initial conditions. Accretion luminosity does not substantially affect the accretion rates experienced by the protostars, and is far less important than dynamical interactions, which can lead to ejections that effectively terminate the accretion. We find that the accretion rates onto the inner regions of the disks (20 AU) around the protostars are highly variable, in contrast to the constant or smoothly decreasing accretion rates currently used in models of the pre-main sequence evolution of Population III stars.Comment: 12 pages, 10 figures and 3 tables. Accepted by MNRA

The role of the exit in the initial screening of investment opportunities: The case of business angel syndicate gatekeepers

The exit process has been largely ignored in business angel research.. The practitioner community identifies the difficulty in achieving exits as the most pressing problem for investors. This has been attributed to the failure of investors to adopt an exit-centric approach to investing. The validity of this claim is examined via a study of the investment approach of 21 ‘gatekeepers’ (managers) of angel groups in Scotland and Northern Ireland. Most gatekeepers say that they do consider the exit when they invest. However, this is contradicted by a verbal protocol analysis which indicates that the exit is not a significant consideration in their initial screening process. The small number of exits achieved by the groups is consistent with the general lack of an exit-centric approach to investing. Only three groups exhibit evidence of a strong exit-centric approach to investing. The lack of exits may have a negative impact on the level of future angel investment activity

Providing Self-Aware Systems with Reflexivity

We propose a new type of self-aware systems inspired by ideas from higher-order theories of consciousness. First, we discussed the crucial distinction between introspection and reflexion. Then, we focus on computational reflexion as a mechanism by which a computer program can inspect its own code at every stage of the computation. Finally, we provide a formal definition and a proof-of-concept implementation of computational reflexion, viewed as an enriched form of program interpretation and a way to dynamically "augment" a computational process.Comment: 12 pages plus bibliography, appendices with code description, code of the proof-of-concept implementation, and examples of executio