On Artifacts in Limited Data Spherical Radon Transform: Curved Observation Surface

In this article, we consider the limited data problem for spherical mean transform. We characterize the generation and strength of the artifacts in a reconstruction formula. In contrast to the third's author work [Ngu15b], the observation surface considered in this article is not flat. Our results are comparable to those obtained in [Ngu15b] for flat observation surface. For the two dimensional problem, we show that the artifacts are $k$ orders smoother than the original singularities, where $k$ is vanishing order of the smoothing function. Moreover, if the original singularity is conormal, then the artifacts are $k+\frac{1}{2}$ order smoother than the original singularity. We provide some numerical examples and discuss how the smoothing effects the artifacts visually. For three dimensional case, although the result is similar to that [Ngu15b], the proof is significantly different. We introduce a new idea of lifting the space

Life cycle assessment of ground mounted photovoltaic panels

Abstract. Nowadays, the problem of carbon emission attracts a lot of attention from people in the world. To solve this problem, many solutions are proposed to get the target of Greenhouse Gas emission reduction. Among of all, the increase of the share of renewable energy is known as a feasible and promising approach for achieving this goal. Solar power and wind power is considered as two dominant renewable sources having a significant contribution to the power generation as well as reducing CO₂ emissions. In this study, ground mounted photovoltaic plant is taken as a approach for achieving this target. The objective of the study was to answer three research questions: (1) What are the life-cycle environmental impacts of ground-mounted photovoltaic (GMPV) systems; (2) What are the missing data to perform life cycle assessment (LCA) of GMPV? and (3)What are the future development projections for GMPV and how would they impact on their LCA? Furthermore, the state of the art of GMPV technology is also reviewed. The thesis is based on the data of Ecoinvent v3.3, available in open LCA, associating with six cases studies on GMPV, will give an evaluation about the state of the art of technology, the data gap of GMPV in Ecoinvent v3.3. The LCA method is known as a quantitative approach which is utilized to make an evaluation of whole process of a product. The four steps of LCA are goal and scope definition, inventory analysis, impact assessment and interpretation. Based on the six case studies from literature, the data gaps were recognized regarding the power output, number of modules, performance module and degradation rate, and the materials in the mounting system. These data gaps are very important because they have the significant impacts on the implementation of LCA approach. If these data gaps were filled, operators would be likely to have a more precise evaluation of GMPV systems. It was concluded that multicrystalline silicon module is the commercially available material with highest efficiency but, because of their high cost, the development is shifted towards CdTe thin film materials. CdTe thin film is gradually proving its position in the photovoltaic (PV) commercial market because of growing efficiency and reasonable cost, which are very important when applying in the large scale of GMPV systems. Finally, it was suggested that the third generation technology, which is the combination between Generation 1 technology and Generation II technology with the feature of high efficiency and reasonable cost, has the highest potential for applying in GMPV

Solid-state electronic spin coherence time approaching one second

Solid-state electronic spin systems such as nitrogen-vacancy (NV) color centers in diamond are promising for applications of quantum information, sensing, and metrology. However, a key challenge for such solid-state systems is to realize a spin coherence time that is much longer than the time for quantum spin manipulation protocols. Here we demonstrate an improvement of more than two orders of magnitude in the spin coherence time ($T_2$) of NV centers compared to previous measurements: $T_2 \approx 0.5$ s at 77 K, which enables $\sim 10^7$ coherent NV spin manipulations before decoherence. We employed dynamical decoupling pulse sequences to suppress NV spin decoherence due to magnetic noise, and found that $T_2$ is limited to approximately half of the longitudinal spin relaxation time ($T_1$) over a wide range of temperatures, which we attribute to phonon-induced decoherence. Our results apply to ensembles of NV spins and do not depend on the optimal choice of a specific NV, which could advance quantum sensing, enable squeezing and many-body entanglement in solid-state spin ensembles, and open a path to simulating a wide range of driven, interaction-dominated quantum many-body Hamiltonians

Application of Isotonic Regression in Predicting Business Risk Scores

An isotonic regression model fits an isotonic function of the explanatory variables to estimate the expectation of the response variable. In other words, as the function increases, the estimated expectation of the response must be non-decreasing. With this characteristic, isotonic regression could be a suitable option to analyze and predict business risk scores. A current challenge of isotonic regression is the decrease of performance when the model is fitted in a large data set e.g. more than four or five dimensions. This paper attempts to apply isotonic regression models into prediction of business risk scores using a large data set – approximately 50 numeric variables and 24 million observations. Evaluations are based on comparing the new models with a traditional logistic regression model built for the same data set. The primary finding is that isotonic regression using distance aggregate functions does not outperform logistic regression. The performance gap is narrow however, suggesting that isotonic regression may still be used if necessary since isotonic regression may achieve better convergence speed in massive data sets

Listening to the Outliers: Refining the Curriculum for Dissertation Camps

Seeking to support graduate student writers, writing centers at research universities have developed highly successful dissertation camps over the past 15 years. Previous research from North American dissertation camps has demonstrated significant benefits from these camps, as dissertation writers developed new writing habits and increased their productivity. In this study, however, a closer look at initial and follow-up survey responses provided by participants from dissertation camps at two institutions—an Upper Midwestern university in the United States that has held camps for 11 years and an Eastern European university that held an online camp during the 2020 pandemic—suggests that focusing on the positive responses may obscure some telling tensions between dissertation camps’ benefits and limitations. Our research reveals tensions around four key parts of dissertation camp curricula—developing writing habits and schedules, sustaining a community of writers, focusing on the drafting stage, and emphasizing cross- disciplinary participation. Listening more deeply to these outlier responses sheds valuable light on the affordances and limitations of dissertation writing camps and on how the curricula of dissertation camps might be reimagined to better articulate and embrace those tensions

Individual Differences in Dopamine Are Associated with Reward Discounting in Clinical Groups But Not in Healthy Adults.

Some people are more willing to make immediate, risky, or costly reward-focused choices than others, which has been hypothesized to be associated with individual differences in dopamine (DA) function. In two studies using PET imaging, one empirical (Study 1: N = 144 males and females across 3 samples) and one meta-analytic (Study 2: N = 307 across 12 samples), we sought to characterize associations between individual differences in DA and time, probability, and physical effort discounting in human adults. Study 1 demonstrated that individual differences in DA D2-like receptors were not associated with time or probability discounting of monetary rewards in healthy humans, and associations with physical effort discounting were inconsistent across adults of different ages. Meta-analytic results for temporal discounting corroborated our empirical finding for minimal effect of DA measures on discounting in healthy individuals but suggested that associations between individual differences in DA and reward discounting depend on clinical features. Addictions were characterized by negative correlations between DA and discounting, but other clinical conditions, such as Parkinson's disease, obesity, and attention-deficit/hyperactivity disorder, were characterized by positive correlations between DA and discounting. Together, the results suggest that trait differences in discounting in healthy adults do not appear to be strongly associated with individual differences in D2-like receptors. The difference in meta-analytic correlation effects between healthy controls and individuals with psychopathology suggests that individual difference findings related to DA and reward discounting in clinical samples may not be reliably generalized to healthy controls, and vice versa.SIGNIFICANCE STATEMENT Decisions to forgo large rewards for smaller ones due to increasing time delays, uncertainty, or physical effort have been linked to differences in dopamine (DA) function, which is disrupted in some forms of psychopathology. It remains unclear whether alterations in DA function associated with psychopathology also extend to explaining associations between DA function and decision making in healthy individuals. We show that individual differences in DA D2 receptor availability are not consistently related to monetary discounting of time, probability, or physical effort in healthy individuals across a broad age range. By contrast, we suggest that psychopathology accounts for observed inconsistencies in the relationship between measures of DA function and reward discounting behavior

Gingival Transcriptome of Innate Antimicrobial Factors and the Oral Microbiome with Aging and Periodontitis

The epithelial barrier at mucosal sites comprises an important mechanical protective feature of innate immunity, and is intimately involved in communicating signals of infection/tissue damage to inflammatory and immune cells in these local environments. A wide array of antimicrobial factors (AMF) exist at mucosal sites and in secretions that contribute to this innate immunity. A non-human primate model of ligature-induced periodontitis was used to explore characteristics of the antimicrobial factor transcriptome (n = 114 genes) of gingival biopsies in health, initiation and progression of periodontal lesions, and in samples with clinical resolution. Age effects and relationship of AMF to the dominant members of the oral microbiome were also evaluated. AMF could be stratified into 4 groups with high (n = 22), intermediate (n = 29), low (n = 18) and very low (n = 45) expression in healthy adult tissues. A subset of AMF were altered in healthy young, adolescent and aged samples compared with adults (e.g., APP, CCL28, DEFB113, DEFB126, FLG2, PRH1) and were affected across multiple age groups. With disease, a greater number of the AMF genes were affected in the adult and aged samples with skewing toward decreased expression, for example WDC12, PGLYRP3, FLG2, DEFB128, and DEF4A/B, with multiple age groups. Few of the AMF genes showed a \u3e2-fold increase with disease in any age group. Selected AMF exhibited significant positive correlations across the array of AMF that varied in health and disease. In contrast, a rather limited number of the AMF significantly correlated with members of the microbiome; most prominent in healthy samples. These correlated microbes were different in younger and older samples and differed in health, disease and resolution samples. The findings supported effects of age on the expression of AMF genes in healthy gingival tissues showing a relationship to members of the oral microbiome. Furthermore, a dynamic expression of AMF genes was related to the disease process and showed similarities across the age groups, except for low/very low expressed genes that were unaffected in young samples. Targeted assessment of AMF members from this large array may provide insight into differences in disease risk and biomolecules that provide some discernment of early transition to disease

Anti-Reflection Coating for Nitrogen-Vacancy Optical Measurements in Diamond

We realize anti-reflection (AR) coatings for optical excitation and fluorescence measurements of nitrogen-vacancy (NV) color centers in bulk diamond by depositing quarter-wavelength thick silica layers on the diamondsurface. These AR coatings improve NV-diamond optical measurements by reducing optical reflection at the diamond-air interface from ≈17% to ≈2%, which allows more effective NV optical excitation and more efficient detection of NV fluorescence. We also show that diamondAR coatings eliminate standing-wave interference patterns of excitation laser intensity within bulk diamond, and thereby greatly reduce spatial variations in NV fluorescence, which can degrade spatially resolved magnetic field sensing using NV centers.Engineering and Applied SciencesPhysic