Competition and Innovation in Markets with Technology Leaders

In this article, we consider technology leaders (which are innovators) and technology followers (which are non-innovators) to provide a new theoretical explanation for the well-cited empirical evidence of an inverted-U relationship between competition and aggregate innovation. We consider a two-stage game with a deterministic Research and Development (R&D) process, where the leaders first determine their R&D investments simultaneously and then all leaders and followers determine their outputs simultaneously. We show that the inverted-U relationship between competition and aggregate innovation occurs if competition is affected by the number of technology followers. However, the presence of more technology leaders decreases individual R&D investments while increasing aggregate R&D investments. If the total number of firms remains the same but the composition of technology leaders and followers changes in favor of leaders (followers), individual R&D investments decrease (increase) but aggregate R&D investments increase (decrease). The relationship between competition and R&D investments can be U-shaped if the intensity of competition is measured by product substitutability. Contrary to the standard expectation, the presence of more firms may reduce welfare

Phylogenetic Analysis and Rapid Identification of the Whitefly, Bemisia afer, in China

The phylogenetic relationship between the whitefly Bemisia afer (Priesner & Hosny) (Hemiptera: Aleyrodidae) from China and other populations among the world were analyzed based on the mitochondrial cytochrome oxidase I (mtCOI) gene. Phylogenetic analysis of mtCOI sequences and those of reference B. afer sequences showed that the populations of the species could be separated into 5 clades (I–V). There were at least two clades of the species from China (IV and V). These data suggested that B. afer might be a species complex. The Chinese B. afer populations were most divergent with B. afer from the United Kingdom and African countries. The distance between the Chinese B. afer (IV and V) and clades I, II, and III is more than 32%, while the distance among clades I, II, III is lower than 7.7%. A new set of primers specific to B. afer was designed to amplify a region of approximately 400 bp to discriminate B. afer from other Bemisia species in China based on mtCOI sequences

Molecular dynamics study of the fragmentation of silicon doped fullerenes

Tight binding molecular dynamics simulations, with a non orthogonal basis set, are performed to study the fragmentation of carbon fullerenes doped with up to six silicon atoms. Both substitutional and adsorbed cases are considered. The fragmentation process is simulated starting from the equilibrium configuration in each case and imposing a high initial temperature to the atoms. Kinetic energy quickly converts into potential energy, so that the system oscillates for some picoseconds and eventually breaks up. The most probable first event for substituted fullerenes is the ejection of a C2 molecule, another very frequent event being that one Si atom goes to an adsorbed position. Adsorbed Si clusters tend to desorb as a whole when they have four or more atoms, while the smaller ones tend to dissociate and sometimes interchange positions with the C atoms. These results are compared with experimental information from mass abundance spectroscopy and the products of photofragmentation.Comment: Seven two-column pages, six postscript figures. To be published in Physical Review

Perception and awareness of diabetes risk and reported risk-reducing behaviors in adolescents

IMPORTANCE: Lifestyle change is central to diabetes risk reduction in youth with overweight or obesity. Feeling susceptible to a health threat can be motivational in adults. OBJECTIVE: To evaluate associations between diabetes risk perception and/or awareness and health behaviors in youth. DESIGN, SETTING, AND PARTICIPANTS: This cross-sectional study analyzed data from the US National Health and Nutrition Examination Survey 2011 to 2018. Participants included youths aged 12 to 17 years with body mass index (BMI) in the 85th percentile or higher without known diabetes. Analyses were conducted from February 2022 to February 2023. MAIN OUTCOMES AND MEASURES: Outcomes included physical activity, screen time, and attempted weight loss. Confounders included age, sex, race and ethnicity, and objective diabetes risk (BMI, hemoglobin A1c [HbA1c]). EXPOSURES: Independent variables included diabetes risk perception (feeling at risk) and awareness (told by clinician), as well as potential barriers (eg, food insecurity, household size, insurance). RESULTS: The sample included 1341 individuals representing 8 716 794 US youths aged 12 to 17 years with BMI in the 85th percentile or higher for age and sex. The mean age was 15.0 years (95% CI, 14.9-15.2 years) and mean BMI z score was 1.76 (95% CI 1.73-1.79). Elevated HbA1c was present in 8.6% (HbA1c 5.7%-6.4%: 8.3% [95% CI, 6.5%-10.5%]; HbA1c ≥6.5%: 0.3% [95% CI, 0.1%-0.7%]). Nearly one-third of youth with elevated HbA1c reported risk perception (30.1% [95% CI, 23.1%-38.1%), while one-quarter (26.5% [95% CI, 20.0%-34.2%]) had risk awareness. Risk perception was associated with increased TV watching (β = 0.3 hours per day [95% CI, 0.2-0.5 hours per day]) and approximately 1 less day per week with at least 60 minutes of physical activity (β = -1.2 [95% CI, -2.0 to -0.4) but not with nutrition or weight loss attempts. Awareness was not associated with health behaviors. Potential barriers had mixed associations: larger households (≥5 members vs 1-2) reported lower consumption of non-home-prepared meals (OR 0.4 [95% CI, 0.2-0.7]) and lower screen time (β = -1.1 hours per day [95% CI, -2.0 to -0.3 hours per day), while public insurance (vs private) was associated with approximately 20 fewer minutes per day of physical activity (β = -20.7 minutes per day [95% CI, 35.5 to -5.8 minutes per day]). CONCLUSIONS AND RELEVANCE: In this cross-sectional study including a US-representative sample of adolescents with overweight or obesity, diabetes risk perception and awareness were not associated with greater engagement in risk-reducing behaviors in youth. These findings suggest the need to address barriers to engagement in lifestyle change, including economic disadvantage

Competition and Innovation in Markets with Technology Leaders

We consider technology leaders (which are innovators) and technology followers (which are non-innovators) to provide a new theoretical explanation for the well-cited empirical evidence of an inverted-U relationship between competition and aggregate innovation. We consider a two-stage game with a deterministic R&D process where the leaders first determine their R&D investments simultaneously and then all the leaders and the followers determine their outputs simultaneously. We show that the inverted-U relationship between competition and aggregate innovation occurs if competition is affected by the number of technology followers. However, the presence of more technology leaders decreases individual R&D investments but increases aggregate R&D investments. If the total number of firms remains the same but the composition of the technology leaders and followers changes in favor of the leaders (followers), the individual R&D investments decrease (increase) but the aggregate R&D investments increase (decrease). The relationship between competition and R&D investments can be U-shaped if the intensity of competition is measured by product substitutability. Contrary to the standard expectation, the presence of more firms may reduce welfare

Electrodynamics of Media

Contains research objectives, summary of research and reports on three research projects.Joint Services Electronics Program (Contract DAAB07-75-C-1346)California Institute of Technology (Contract 953524

Some BPS configurations of the BLG Theory

We obtain BPS configurations of the BLG theory and its variant including mass terms for scalars and fermions in addition to a background field with different world-volume and R-symmetries. Three cases are considered, with world-volume symmetries SO(1,1) and SO(2) and preserving different amounts of supersymmetry. In the former case we obtain a singular configuration preserving N=(3,3) supersymmetry and an one-quarter BPS configuration corresponding to intersecting M2-M5-M5-branes. In the latter instance the BPS equations are reduced to those in the self-dual Chern-Simons theory with two complex scalars. In want of an exact solution, we find a topological vortex solution numerically in this case. Other solutions are given by combinations of domain walls.Comment: 15 pages, 3 figure

Chemically specifi C multiscale modeling of clay-polymer nanocomposites reveals intercalation dynamics, tactoid self-assembly and emergent materials properties

A quantitative description is presented of the dynamical process of polymer intercalation into clay tactoids and the ensuing aggregation of polymerentangled tactoids into larger structures, obtaining various characteristics of these nanocomposites, including clay-layer spacings, out-of-plane clay-sheet bending energies, X-ray diffractograms, and materials properties. This model of clay-polymer interactions is based on a three-level approach, which uses quantum mechanical and atomistic descriptions to derive a coarse-grained yet chemically specifi c representation that can resolve processes on hitherto inaccessible length and time scales. The approach is applied to study collections of clay mineral tactoids interacting with two synthetic polymers, poly(ethylene glycol) and poly(vinyl alcohol). The controlled behavior of layered materials in a polymer matrix is centrally important for many engineering and manufacturing applications. This approach opens up a route to computing the properties of complex soft materials based on knowledge of their chemical composition, molecular structure, and processing conditions.This work was funded in part by the EU FP7 MAPPER project (grant number RI-261507) and the Qatar National Research Fund (grant number 09–260–1–048). Supercomputing time was provided by PRACE on JUGENE (project PRA044), the Hartree Centre (Daresbury Laboratory) on BlueJoule and BlueWonder via the CGCLAY project, and on HECToR and ARCHER, the UK national supercomputing facility at the University of Edinburgh, via EPSRC through grants EP/F00521/1, EP/E045111/1, EP/I017763/1 and the UK Consortium on Mesoscopic Engineering Sciences (EP/L00030X/1). The authors are grateful to Professor Julian Evans for stimulating discussions during the course of this project. Data-storage and management services were provided by EUDAT (grant number 283304)

Multiclass Semantic Segmentation to Identify Anatomical Sub-Regions of Brain and Measure Neuronal Health in Parkinson's Disease

Automated segmentation of anatomical sub-regions with high precision has become a necessity to enable the quantification and characterization of cells/ tissues in histology images. Currently, a machine learning model to analyze sub-anatomical regions of the brain to analyze 2D histological images is not available. The scientists rely on manually segmenting anatomical sub-regions of the brain which is extremely time-consuming and prone to labeler-dependent bias. One of the major challenges in accomplishing such a task is the lack of high-quality annotated images that can be used to train a generic artificial intelligence model. In this study, we employed a UNet-based architecture, compared model performance with various combinations of encoders, image sizes, and sample selection techniques. Additionally, to increase the sample set we resorted to data augmentation which provided data diversity and robust learning. In this study, we trained our best fit model on approximately one thousand annotated 2D brain images stained with Nissl/ Haematoxylin and Tyrosine Hydroxylase enzyme (TH, indicator of dopaminergic neuron viability). The dataset comprises of different animal studies enabling the model to be trained on different datasets. The model effectively is able to detect two sub-regions compacta (SNCD) and reticulata (SNr) in all the images. In spite of limited training data, our best model achieves a mean intersection over union (IOU) of 79% and a mean dice coefficient of 87%. In conclusion, the UNet-based model with EffiecientNet as an encoder outperforms all other encoders, resulting in a first of its kind robust model for multiclass segmentation of sub-brain regions in 2D images

Integration and Application of a Fiber-Optic Sensing System for Monitoring Debris Flows

This study presents an innovative fiber-optic sensing system for monitoring debris flows. The system mainly comprises an interrogator and four fiber Bragg grating accelerometers. The field tests show that signal-to-noise-ratio (SNR) of the fiber-optic sensor is 10 dB higher than that of a geophone. Following confirmation of the reliability of the proposed sensing system, the systems are deployed along the Ai-Yu-Zi and Chu-Shui Creeks in Nautou County, Taiwan, for monitoring debris flows. The four accelerometers are installed in series. The systems have detected several debris flows in 2012. The monitored data reveal that the frequency range of the acceleration of ground vibration is 10-150 Hz, which is the same as that of the velocity of ground vibration detected by a sensing system that includes geophones. Because the fiber-optic sensing system is more sensitive than the geophone system, the proposed fiber-optic sensing system is highly promising for use in monitoring natural disasters that generate ground vibrations.本研究藉由組合光纖光柵加速度計、解調儀、及其他相關元件，發展一套可偵測土 石流之光纖感測系統。現地測試結果顯示，與目前常用含地聲檢知器的土石流感測系統相較， 本系統所測得地表振動訊號之訊雜比比前者高10 dB。在測試系統量測效能後，將此系統分別 架設於南投縣信義鄉神木村之愛玉子溪及出水溪上。系統中採串連方式配置四個光纖加速度 計，並於2012 年監測到多場土石流。觀測結果顯示，光纖感測系統所測得土石流所造成地表 振動之加速度，與過去地聲檢知器所測得土石流地表振動速度，兩者頻率一樣，均為10–150 Hz。由於光纖光柵加速度計相較於地聲檢知器更為靈敏，因此，除了可應用於偵測土石流外， 也可應用於監測會產生地表振動的其他坡地災害，如：落石及山崩等