This paper deals with optimal partitioning of limited testing time in order to achieve maximum total test score. Nonlinear optimization theory was used to analyze this problem. A general case using a generic item response model is first presented. A special case that applies a response time model proposed by Wang and Hanson (2005) is also presented. Theoretical properties of the optimal solution are derived. Their practical implications to optimal test-taking strategies are also discussed. The theoretical properties are in general agreement with the conventional advice to the examinees on pacing strategy.

Autonomous exploration in unknown environments has become a critical capability of mobile robots. Many methods often suffer from problems such as exploration goal selection based solely on information gain and inefficient tour optimization. Recent reinforcement learning-based methods do not consider full area coverage and the performance of transferring learned policy to new environments cannot be guaranteed. To address these issues, a dual-stage exploration method has been proposed, which combines spatial clustering of possible exploration goals and Traveling Salesman Problem (TSP) based tour planning on both local and global scales, aiming for efficient full-area exploration in highly convoluted environments. Our method involves two stages: exploration and relocation. During the exploration stage, we introduce to generate local navigation goal candidates straight from clusters of all possible local exploration goals. The local navigation goal is determined through tour planning, utilizing the TSP framework. Moreover, during the relocation stage, we suggest clustering all possible global exploration goals and applying TSP-based tour planning to efficiently direct the robot toward previously detected but yet-to-be-explored areas. The proposed method is validated in various challenging simulated and real-world environments. Experimental results demonstrate its effectiveness and efficiency. Videos and code are available at https://github.com/JiatongBao/exploration.

In order to gain a better understanding of clay and Fe (oxyhydr)oxide minerals formed during pedogenesis of basalts in tropical monsoonal Hainan (southern China), a basalt-derived lateritic soil at Nanyang, Hainan, was investigated comprehensively. The results show that the lateritic regolith consists uniformly of kaolinite and Fe (oxyhydr)oxide minerals, with trace gibbsite only in the AE horizon. Abundant dioctahedral smectite in the basalt bedrock formed due to primary hydrothermal alteration, and transformed to kaolinite rapidly in the highly weathering saprolite horizon. The ‘crystallinity’ of kaolinite is notably low and its Hinckley index fluctuates along the soil profile, resulting from intense ferrolysis due to fluctuations between wet/dry climate conditions. From the base to the top of the profile, maghemite shows a decreasing trend, whereas magnetite, hematite, and goethite exhibit a slightly increasing trend, indicating that maghemite formed as an initial product of basalt weathering. Formation of Fe (oxyhydr)oxide species in basalt-derived soil is mainly controlled by local environmental conditions such as soil moisture, redox, and acidic conditions; thus, iron mineral-based paleoclimatic proxies could not be used for subtropical to tropical soils. The highly weathered saprolite has a similar δ56Fe value (+0.06‰) to that (+0.07‰) of the parent rock, while the AE to middle E horizons have greater δ56Fe values of +0.12‰ to +0.19‰. Fe isotopic signatures correlate positively with the Fe mass transfer coefficient (R2=0.77, n=6, ρ<0.05), indicating repetitive weathering and relative accumulation of isotopically heavier Fe in the upper soil horizons, which occurred by reductive dissolution of organic matter under oxic conditions, as reflected by the greater U/Th.

The current studies investigated how a manipulation in joint outcome influenced individuals’ responses to pro-equality/individualistic decision makers. In Study 1 (N = 175), we examined the impact of whether equal distribution led to maximum joint outcome or not on individuals’ evaluations of, and reactions to, partners choosing either equal or individualistic distributions. In Study 2 (N = 164), we further examined the moderating roles of individual differences in general social value orientation (SVO) and preferences for joint outcome (vs. equality). Important findings include: a) individuals evaluated a pro-equality partner as less warm when equal distribution did not afford maximum joint outcome than when it did; b) individuals, especially those who scored high on preferences for joint outcome (relative to equality), were less likely to chose equal distribution when equality did not maximize joint outcome than when it did; and c) individuals who preferred joint outcome to equality evaluated individualistic partners as warmer when equal distribution did not yield maximum joint outcome than when it did. Theoretical and practical implications of these findings are discussed.

Hyperinsulinaemia and insulin resistance have been proposed to be associated with mortality risk, and diet can modulate insulin response. However, whether dietary patterns with high insulinaemic potential are associated with mortality remains unknown. We prospectively examined the associations between hyperinsulinaemic diets and the risk of total and cause-specific mortality in a large nationally representative population. Dietary factors were assessed by 24-h recalls. Two empirical dietary indices for hyperinsulinaemia (EDIH) and insulin resistance (EDIR) were developed to identify food groups most predictive of biomarkers for hyperinsulinaemia (C-peptide and insulin) and insulin resistance (homoeostatic model assessment for insulin resistance), respectively. Deaths from date of the first dietary interview until 31 December 2015 were identified by the National Death Index. Multivariable hazard ratios (HR) and 95 % CI were calculated using Cox regression models. During a median follow-up of 7·8 years, 4904 deaths were documented among 40 074 participants. For EDIH, the multivariable-adjusted HR (comparing extreme quintiles) were 1·20 (95 % CI 1·09, 1·32, P-trend<0·001) for overall mortality and 1·41 (95 % CI 1·15, 1·74, P-trend = 0·002) for CVD mortality. Similar associations were observed for EDIR with HR of 1·18 (95 % CI 1·07, 1·29, P-trend < 0·001) for total and 1·35 (95 % CI 1·09, 1·67, P-trend = 0·005) for CVD mortality. After further adjustments for BMI and diabetes, these positive associations were somewhat attenuated. Our findings suggested that diets with higher insulinaemic potential are associated with increased risk of overall and CVD-specific mortality.

Inflammation is a central mechanism in metabolic disorders associated with morbidity and mortality and dietary factors can modulate inflammation. We aimed to prospectively investigate the association between an empirically developed, food-based dietary inflammatory pattern (EDIP) score and the risk of overall and cause-specific mortality, using data from the US National Health and Nutrition Examination Survey from 1999 to 2014. EDIP score was derived by entering thirty-nine predefined commonly consumed food groups into the reduced rank regression models followed by stepwise linear regression, which was most predictive of two plasma inflammation biomarkers including C-reactive protein and leucocyte count among 25 500 US adults. This score was further validated in a testing set of 9466 adults. Deaths from baseline until 31 December 2015 were identified through record linkage to the National Death Index. During a median follow-up of 7·8 years among 40 074 participants, we documented 4904 deaths. Compared with participants in the lowest quintile of EDIP score, those in the highest quintile had a higher risk of overall death (hazard ratio (HR) = 1·19, 95 % CI 1·08, 1·32, Ptrend = 0·002), and deaths from cancer (HR = 1·41, 95 % CI 1·14, 1·74, Ptrend = 0·017) and CVD (HR = 1·22, 95 % CI 0·98, 1·53, Ptrend = 0·211). When stratified by age, the association of EDIP with overall mortality was stronger among individuals under 65 years of age (Pinteraction = 0·001). Diets with a higher inflammatory potential were associated with increased risk of overall and cancer-specific mortality. Interventions to reduce the adverse effect of pro-inflammatory diets may potentially promote health and longevity.

In this study, we have spectroscopically investigated the plasma generated by a Q-switched Nd:YAG laser operating at its fundamental wavelength of 1064 nm focused on magnesium (Mg) and titanium (Ti) target samples in the air under atmospheric pressure. We employed circular cavities of radii (2.5, 3.0, and 3.5 mm) and a square cavity to investigate the cavity confinement effect on the spectral emission intensities of the plasmas. We observed that the circular cavity of radius 2.5 mm had the maximum signal enhancement, and this can be attributed to the compression of the plasma and reheating by the reflected shock waves. The maximum enhancement factor of the Mg I-518.4 nm line was reached at approximately 3.8, 3.4, and 2.8 with a circular cavity of radius 2.5, 3.0, and 3.5 mm, respectively, at a delay time of 350 ns and a laser energy of 350 mJ. By applying varying external magnetic fields (0.47, 0.62, 0.91, and 1.23 T) across the generated plasma, the plasma parameters such as electron temperature and number density have been investigated. From our results, we observed that the radius of the cavity had a tremendous effect on the enhancement of the emission signal intensities. We also found that the increase in the electron temperature and the number density can be attributed to the increase in the applied magnetic field and the laser energy. From our calculations, the value of β, which was less than 1 for all the cases, confirms that there was a plasma confinement at the presence of the magnetic field.

We consider a resource allocation model to analyze investment strategies for financial services firms in order to minimize their operational risk losses. A firm has to decide how much to invest in human resources and in infrastructure (information technology). The operational risk losses are a function of the activity level of the firm, of the amounts invested in personnel and in infrastructure, and of interaction effects between the amounts invested in personnel and infrastructure. We first consider a deterministic setting and show certain monotonicity properties of the optimal investments assuming general loss functions that are convex. We find that because of the interaction effects “economies of scale" may not hold in our setting, in contrast to a typical manufacturing environment. We then consider a general polynomial loss function in a stochastic setting with the number of transactions at the firm being a random variable. We characterize the asymptotic behaviors of the optimal investments in both heavy and light trading environments. We show that when the market is very liquid, that is, it is subject to heavy transaction volumes, it is optimal for a financial firm that is highly risk sensitive to use a balanced investment strategy. Both a heavier right tail of the distribution of transaction volume and a firm's risk sensitivity necessitate larger investments; in a heavy trading environment these two factors reinforce one another. However, in a light trading environment with the transaction volume having a heavy left tail the investment will be independent of the firm's sensitivity to risk.

Patch antennas with a meandering slot and different distributions of grounded metallic vias are presented in this paper. The meandering slot is adopted to stimulate dual-band operation, while the number and position of the grounded metallic vias are suggested to achieve different radiation performances. The characteristics are analyzed in detail where we find that the existence of the vias also improves the impedance matching. Four samples are designed, where dual-band with both linear polarization, dual-band with circular- and linear-polarization, and single band with linear polarization are obtained, respectively. The samples are finally fabricated and the measurement results agree well with the simulation results.

We report progress in growing non-polar a-plane III-nitride films and heterostructures over a-plane 4H-SiC. a-plane SiC is more closely lattice-matched to a-plane GaN than is r-plane sapphire. Consequently, better structural quality a-plane nitride films may result over a-plane SiC substrates. By migration enhanced metalorganic chemical vapor deposition (MEMOCVD), an atomically smooth (1120)AlN layer with RMS roughness of 0.3nm was obtained. From the results of XRD, the structural defects in the AlN layer on SiC substrates were strongly reduced compared to those grown on r-plane sapphire. Also by applying our selective area lateral epitaxy (SALE) growth procedure, we achieved high structural and optical quality a-plane GaN films on 4H-SiC with RMS roughness only 0.4nm. Therefore, non-polar III-nitride films and heterostructures on SiC substrates are promising building blocks for realizing high performance polarization-free devices.