Changing Stakeholder Needs and Changing Evaluator Roles: The Central Valley Partnership of the James Irvine Foundation

This case study describes the evolution of the evaluator's role as the program evolved and developed, and as the needs of the client and intended users changed over time. The initiative aimed to assist immigrants in California's Central Valley. The case illustrates important tensions among accountability, learning and capacity building purposes of evaluation

Voltage-dependent first-principles simulation of insertion of chloride ions into Al/Al2_2O3_3 interfaces using the Quantum Continuum Approximation

Experiments have shown that pitting corrosion can develop in aluminum surfaces at potentials $> -0.5$ V relative to the standard hydrogen electrode (SHE). Until recently, the onset of pitting corrosion in aluminum has not been rigorously explored at an atomistic scale because of the difficulty of incorporating a voltage into density functional theory (DFT) calculations. We introduce the Quantum Continuum Approximation (QCA) which self-consistently couples explicit DFT calculations of the metal-insulator and insulator-solution interfaces to continuum Poisson-Boltzmann electrostatic distributions describing the bulk of the insulating region. By decreasing the number of atoms necessary to explicitly simulate with DFT by an order of magnitude, QCA makes the first-principles prediction of the voltage of realistic electrochemical interfaces feasible. After developing this technique, we apply QCA to predict the formation energy of chloride atoms inserting into oxygen vacancies in Al(111)/$\alpha$-Al$_2$O$_3$ (0001) interfaces as a function of applied voltage. We predict that chloride insertion is only favorable in systems with a grain boundary in the Al$_2$O$_3$ for voltages $> -0.2$ V (SHE). Our results roughly agree with the experimentally demonstrated onset of corrosion, demonstrating QCA's utility in modeling realistic electrochemical systems at reasonable computational cost.Comment: 20 pages, 6 figure

Electronic structure of boron and aluminum δ\delta-doped layers in silicon

Recent work on atomic-precision dopant incorporation technologies has led to the creation of both boron and aluminum $\delta$-doped layers in silicon with densities above the solid solubility limit. We use density functional theory to predict the band structure and effective mass values of such $\delta$ layers, first modeling them as ordered supercells. Structural relaxation is found to have a significant impact on the impurity band energies and effective masses of the boron layers, but not the aluminum layers. However, disorder in the $\delta$ layers is found to lead to significant flattening of the bands in both cases. We calculate the local density of states and doping potential for these $\delta$-doped layers, demonstrating that their influence is highly localized with spatial extents at most 4 nm. We conclude that acceptor $\delta$-doped layers exhibit different electronic structure features dependent on both the dopant atom and spatial ordering. This suggests prospects for controlling the electronic properties of these layers if the local details of the incorporation chemistry can be fine tuned.Comment: Main text 8 pages, 6 figures + Appendices 3 pages, 2 figure

Quantum-Inspired Tempering for Ground State Approximation using Artificial Neural Networks

A large body of work has demonstrated that parameterized artificial neural networks (ANNs) can efficiently describe ground states of numerous interesting quantum many-body Hamiltonians. However, the standard variational algorithms used to update or train the ANN parameters can get trapped in local minima, especially for frustrated systems and even if the representation is sufficiently expressive. We propose a parallel tempering method that facilitates escape from such local minima. This methods involves training multiple ANNs independently, with each simulation governed by a Hamiltonian with a different "driver" strength, in analogy to quantum parallel tempering, and it incorporates an update step into the training that allows for the exchange of neighboring ANN configurations. We study instances from two classes of Hamiltonians to demonstrate the utility of our approach using Restricted Boltzmann Machines as our parameterized ANN. The first instance is based on a permutation-invariant Hamiltonian whose landscape stymies the standard training algorithm by drawing it increasingly to a false local minimum. The second instance is four hydrogen atoms arranged in a rectangle, which is an instance of the second quantized electronic structure Hamiltonian discretized using Gaussian basis functions. We study this problem in a minimal basis set, which exhibits false minima that can trap the standard variational algorithm despite the problem's small size. We show that augmenting the training with quantum parallel tempering becomes useful to finding good approximations to the ground states of these problem instances.Comment: 13 pages, 6 figures. v2: updated Figs. 3, 4, and 5. v3. included two new QPT schemes. Updated format to SciPost format. 30 pages, 11 figures. Submission to SciPos

Flea‘in Around: A Look at the Identification, Preservation, Clearing, and Mounting of Siphonaptera

Fleas are remarkable and highly specialized insects, with no part of their external anatomy being easily mistaken for that of any other insect. Due to their small size, the subtle differences among the distinguishing morphological characteristics of each species, and complexities of preparing specimens, identifying, and working with fleas is challenging. Various documents and taxonomic keys are available that discuss mounting procedures and the identification of medically important fleas for large regions of the world including the United States; however, many of these have become antiquated over time. Some of the distinguishing specialized characteristics exhibited among flea species, as presented in older keys, come in the form of line drawings, which are accurate but can be difficult to use when comparing it to structures on a whole specimen when viewed through a microscope. This paper presents a guide which describes in detail previously developed, but obscure techniques covering the preservation, preparation, clearing, and mounting of Siphonaptera specimens. In addition, we are also presenting an easy-to-use photographic key of twelve flea species collected from back yard wildlife, as well as pet cats and dogs in Orange County, CA. This key, which is freely available online at the Orange County Mosquito and Vector Control District’s website, is an effective tool for the identification of common flea species found in southern California. Using the key in conjunction with the mounting guide will provide users with a full-circle guide to preserving, identifying, and mounting flea specimens. Keyed flea genera include Cediopsylla, Ctenocephalides, Diamanus, Echidinophaga, Hoplopsyllus, Leptopsylla, Nosopsyllus, Orchopoeas, Pulex, and Xenopsylla. Examined hosts include cats, coyotes, dogs, mice, opossums, rabbits, raccoons, rats, skunks, squirrels, and woodrats

Signal transduction and activator of transcription-3 (STAT3) in patients with colorectal cancer: associations with the phenotypic features of the tumour and host

Purpose: In patients with colorectal cancer (CRC), a high-density local inflammatory infiltrate response is associated with improved survival, whereas elevated systemic inflammatory responses are associated with poor survival. One potential unifying mechanism is the IL-6/JAK/STAT3 pathway. The present study examines the relationship between tumour total STAT3 and phosphorylated STAT3Tyr705 (pSTAT3) expression, host inflammatory responses and survival in patients undergoing resection of stage I-III CRC. Experimental Design: Immunohistochemical assessment of STAT3/pSTAT3 expression was performed using a tissue microarray and tumour cell expression divided into tertiles using the weighted histoscore. The relationship between STAT3/pSTAT3 expression and local inflammatory (CD3+, CD8+, CD45R0+, FOXP3+ T-cell density and Klintrup-Mäkinen grade) and systemic inflammatory responses and cancer-specific survival were examined. Results: 196 patients were included in the analysis. Cytoplasmic and nuclear STAT3 expression strongly correlated (r=0.363, P<0.001); nuclear STAT3 and pSTAT3 expression weakly correlated (r=0.130, P=0.068). Cytoplasmic STAT3 was inversely associated with the density of CD3+ (P=0.012), CD8+ (P=0.003) and FOXP3+ T-lymphocytes (P=0.002) within the cancer cell nests and was associated with an elevated systemic inflammatory response as measured by modified Glasgow Prognostic Score (mGPS2: 19% vs. 4%, P=0.004). The combination of nuclear STAT3/pSTAT3 stratified five-year survival from 81% to 62% (P=0.012), however was not associated with survival independent of venous invasion, tumour perforation or tumour budding. Conclusion In patients undergoing CRC resection, STAT3 expression was associated with adverse host inflammatory responses and reduced survival. Up-regulation of tumour STAT3 may be an important mechanism whereby the tumour deregulates local and systemic inflammatory responses