THE FUTURE OF AGRICULTURAL LABOR

Labor and Human Capital,

Design of an autonomous teleoperated cargo transporting vehicle for lunar base operations

At the turn of the century NASA plans to begin construction of a lunar base. The base will likely consist of developed areas (i.e., habitation, laboratory, landing and launching sites, power plant) separated from each other due to safety considerations. The Self-Repositioning Track Vehicle (SRTV) was designed to transport cargo between these base facilities. The SRTV operates by using two robotic arms to raise and position segments of track upon which the vehicle travels. The SRTV utilizes the semiautonomous mobility (SAM) method of teleoperation; actuator-controlled interlocking track sections; two robotic arms each with five degrees of freedom; and these materials: titanium for structural members and aluminum for shell members, with the possible use of light-weight, high-strength composites

Magna Carta

3rd edition of classic work, with new introduction and additional materialPostprin

A Latter-Day Saint approach to addiction: Aetiology, consequences and treatment in a theological context

This is the author's PDF version of an article published in Religions© 2014. The definitive version is available at http://www.mdpi.com/journal/religionsThis article explores the theological underpinning of the nature, aetiology and treatment of addictions within The Church of Jesus Christ of Latter-day Saints. The first section outlines the “plan of salvation” and how this provides the theological framework for the source and solution to addictions. The final section explores addiction against this background in terms of its aetiology, types, consequences and treatment in a Latter-day Saint context. In so doing it builds on the recognition by the Church in recent years that addiction is a problem in the lives of some of its members and that treatment programs coherent with its teachings and beliefs are necessary. The article concludes by suggesting that while addiction may be more openly discussed within a Latter-day Saint context there is a need to keep this dialogue moving forward. This article does not examine Latter-day Saint teaching within the wider context of psychotherapy and other definitions of addiction; rather it explores the place of addiction as understood within the theological and ecclesiological context of Mormonism

NOVEL TOPOLOGIES IN POLYCYCLIC AROMATIC HYDROCARBONS: A STUDY OF TRIANGULENES AND OTHER MOLECULAR SHAPES

Triangulenes are the homologous series of triangle-shaped polycyclic aromatic hydrocarbons, first contemplated by chemists nearly 100 years ago. Computational models predict that triangulenes will be polyradicals, with high-spin electronic ground states. Recent technological advances have allowed the molecular-scale synthesis and on-surface characterization of the first three members of this series using atomic force microscopy techniques. In this work, a short and scalable synthesis of the [3]triangulene ring system was developed. Cascade cyclization of a tetra-benzyl alcohol precursor in trifluoromethanesulfonic acid solution gave the planar and three-fold symmetrical 4,8,12-trihydro[3]triangulenium carbocation. This new species has been characterized by NMR (nuclear magnetic resonance) and optical spectroscopies and is highly fluorescent. Quenching of the cation into basic solutions or by hydride transfer from triethylsilane provides access to stable dihydro and tetrahydro[3]triangulenes. Quenching with triethylamine gave isomerically pure 1,8-dihydrotriangulene, a known precursor to [3]triangulene. These neutral species interconvert with carbocations in a complex series of proton and hydride transfers. The presence and distribution of these cationic intermediates are determined by acid concentration and time spent in solution. With the help of density functional theory (DFT) calculations, a logical pathway to each isomer was proposed through a series of proton and hydride transfers. This route provides several important [3]triangulene precursors. Preliminary experiments designed to generate [3]triangulene in the solution phase were performed. Reaction of 1,8-dihydrotriangulene with p-chloranil in solution was followed by NMR, optical spectroscopy, and LDI-TOF (laser-desorption-ionization time-of-flight) spectrometry. These experiments provided evidence for the formation and rapid oligomerization of [3]triangulene, consistent with the expectation of its high-spin ground state. The electrochemistry of 1,8-dihydrotriangulene was investigated for the first time. Experiments to date demonstrate a complex series of redox and chemical processes. A related series of topologically interesting structures can be conceptually derived from triangulene by carving out one side and the center ring, or from phenalene by growing rings along two ring faces. When flipped on end, the resulting structure is V-shaped; herein, we refer to these structures as victorenes. Viewed as phenalenyl homologues, the victorenes should not have a simple Kekulé aromatic structure. Also by analogy to the phenalenyl ring system, both the cations and anions in this series are likely to be aromatic. These structures are predicted by our DFT computations to be chiral, with low barriers to interconversion of enantiomers. A new and general synthetic route to victorenes was developed that allowed the preparation of two [3]victorene ketone derivatives. Slight modification of this route enabled the incorporation of substituents that block the reactive sites and afforded clean intramolecular cyclization to several hydro[3]victorenes. The relative free energies of hydro[3]victorenes were calculated using DFT and matched well with the experimental observations. Generation of the first victorenium cations was achieved in a TfOD/DCE-d4 solution, with successful observation by 1H NMR

Reproducibility in Multiple Instance Learning: A Case For Algorithmic Unit Tests

Multiple Instance Learning (MIL) is a sub-domain of classification problems with positive and negative labels and a "bag" of inputs, where the label is positive if and only if a positive element is contained within the bag, and otherwise is negative. Training in this context requires associating the bag-wide label to instance-level information, and implicitly contains a causal assumption and asymmetry to the task (i.e., you can't swap the labels without changing the semantics). MIL problems occur in healthcare (one malignant cell indicates cancer), cyber security (one malicious executable makes an infected computer), and many other tasks. In this work, we examine five of the most prominent deep-MIL models and find that none of them respects the standard MIL assumption. They are able to learn anti-correlated instances, i.e., defaulting to "positive" labels until seeing a negative counter-example, which should not be possible for a correct MIL model. We suspect that enhancements and other works derived from these models will share the same issue. In any context in which these models are being used, this creates the potential for learning incorrect models, which creates risk of operational failure. We identify and demonstrate this problem via a proposed "algorithmic unit test", where we create synthetic datasets that can be solved by a MIL respecting model, and which clearly reveal learning that violates MIL assumptions. The five evaluated methods each fail one or more of these tests. This provides a model-agnostic way to identify violations of modeling assumptions, which we hope will be useful for future development and evaluation of MIL models.Comment: To appear in the 37th Conference on Neural Information Processing Systems (NeurIPS 2023

Peer Mentor Characteristics that Predict Supportive Relationships with First-Year Students: Implications for Peer Mentor Programming and First-Year Student Retention [post-print]

Peer mentoring programs frequently are implemented on college campuses to enhance first-year college student retention; however, few studies have examined characteristics of peer mentors that are associated with more supportive mentor–mentee relationships, leaving college personnel with a limited understanding of how to improve these vital programs. Accordingly, in this prospective study, we examined whether mentors’ attachment style and self-efficacy to mentor predicted peer mentors’ (n = 76) or mentees’ (n = 999) ratings of mentor-provided support. Results showed that mentor self-efficacy mediated the relation between an avoidant attachment style and mentor-reported support; that is, peer mentors with a more avoidant attachment style reported lower self-efficacy to mentor and, in turn, endorsed providing lower levels of support for mentees. Mentor–mentee contact, however, was the only predictor of mentees’ ratings of mentor support. Future research should aim to extend these preliminary findings so as to inform the selection, training, and supervision of peer mentors in college settings, with the ultimate goal of enhancing first-year student retention

Silica attached polymers and ligands for the selective removal of metal ions and radionuclides from aqueous solutions

Surface functionalised silica materials have been prepared, followed by the extensive testing of their ability to remove metal ions from aqueous solutions. Modifications include ligand attachment and polymer grafting from the silica surface whilst the metals tested range from first row transition metals right through to the lanthanides and actinides. Characterisation of the materials produced has been of paramount importance for the understanding of the modification process and this is also extensively discussed. Atom transfer radical polymerisation (ATRP) has been used as the primary polymerisation method. Following polymerisation of 2-hydroxyethyl methacrylate (HEMA), post functionalisation was attempted. However, this was found to cause severe cross-linking and all attempts to attach ligands to this failed. Nonetheless, this process was transferred to grafting from silica surfaces and a novel approach to the characterisation of this material was implemented. (3-aminopropyl) triethoxysilane (APTES) was reacted with multiple forms of silica, primarily ZEOprep silica (average particle size 71.48 μm) and fumed silica (0.007 μm). This produced an amine coated surface to which 2-bromoisobutyryl bromide (BIBB) was attached, providing the required surface for radical polymerisation to proceed with a selected monomer. Solid State Nuclear Magnetic Resonance (SSNMR) has been utilised as the major characterisation technique for each step, leading to significant understanding of how this occurs. Thermogravimetric Analysis (TGA) and elemental analysis has supported this method at each stage whilst also enabling one to calculate the moles of APTES present, per gram of APTES-functionalised silica. For the ZEOprep silica this was calculated to be at up to 1.51 x 10-3 mol g-1 and for the fumed silica 1.63 x 10-3 mol g-1. As well as testing the selective nature of these materials, solutions of individual ions and radionuclides were used to measure the effectiveness of the materials for a specific ion. Rd values for these metals ions including solutions of Co(II), Ni(II), Cu(II), Cd2+, Eu(III) and [UO2]2+ have reached values ranging from 7.49 x 104 mL g-1 to as high as 2.17 x 109 mL g-1. These values are regarded as outstanding by other groups that have reported similar results and these are discussed in the report. This range includes values that were observed when competing Na+ and Ca2+ ions were present at 0.5 % and 1 % (w/w). pH testing was also investigated with the materials using a solution of europium ions to determine the most effective range and this was found to fall between pH 4 and 5. X-ray Photoelectron Spectroscopy (XPS) has been utilised to help gain an understanding of the binding between Cu(II) ions and APTES, suggesting that copper ions bind with oxygen atoms closer to the silica surface as well as the nitrogen atoms at the end of the ligand. Meanwhile STEM (Scanning Transmission Electron Microscope) has been used to show how effectively the surface area of the material is used by imaging the europium ions over a sample of APTES-functionalised fumed silica. Ligands and polymers have been focussed on to build a catalogue of functional materials and this has been achieved in collaboration with PhosphonicS Ltd. The most significant finding from these selective investigations was that uranyl ions were found to be the most readily removed. Cu(II) and Eu(III) ions were also removed relatively effectively whilst Co(II), Ni(II), Zn2+ and Cd2+ proved the most challenging but certainly not impossible. [UO2]2+ concentrations were reduced from 17.1 ppm to 1.6 ppm after 4 weeks with use of the ligand SEA (2-aminoethyl sulfide ethyl silica), even with six other metal ions present at similar initial concentrations and a starting pH of 4.67 by adding just 50 mg of the material to a 45 mL solution