University of Arkansas

About: University of Arkansas is a education organization based out in Fayetteville, Arkansas, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 17225 authors who have published 33329 publications receiving 941102 citations. The organization is also known as: Arkansas & UA.

The evolution of the world trade web: a weighted-network analysis

Abstract: This paper employs a weighted network approach to study the empirical properties of the web of trade relationships among world countries, and its evolution over time. We show that most countries are characterized by weak trade links; yet, there exists a group of countries featuring a large number of strong relationships, thus hinting to a core-periphery structure. Also, better-connected countries tend to trade with poorly-connected ones, but are also involved in highly-interconnected trade clusters. Furthermore, rich countries display more intense trade links and are more clustered. Finally, all network properties are remarkably stable across the years and do not depend on the weighting procedure.

COVID-19 Home Confinement Negatively Impacts Social Participation and Life Satisfaction: A Worldwide Multicenter Study.

Abstract: Public health recommendations and governmental measures during the new coronavirus disease (COVID-19) pandemic have enforced numerous restrictions on daily living including social distancing, isolation, and home confinement. While these measures are imperative to mitigate spreading of COVID-19, the impact of these restrictions on psychosocial health is undefined. Therefore, an international online survey was launched in April 2020 to elucidate the behavioral and lifestyle consequences of COVID-19 restrictions. This report presents the preliminary results from more than one thousand responders on social participation and life satisfaction. Methods: Thirty-five research organizations from Europe, North-Africa, Western Asia, and the Americas promoted the survey through their networks to the general society, in 7 languages (English, German, French, Arabic, Spanish, Portuguese, and Slovenian). Questions were presented in a differential format with questions related to responses “before” and “during” confinement conditions. Results: 1047 participations (54% women) from Asia (36%), Africa (40%), Europe (21%), and others (3%) were included in the analysis. Findings revealed psychosocial strain during the enforced COVID-19 home confinement. Large decreases (p < 0.001) in the amount of social activity through family (−58%), friends/neighbors (−44.9%), or entertainment (−46.7%) were triggered by the enforced confinement. These negative effects on social participation were also associated with lower life satisfaction (−30.5%) during the confinement period. Conversely, the social contact score through digital technologies significantly increased (p < 0.001) during the confinement period with more individuals (+24.8%) being socially connected through digital technology. Conclusion: These preliminary findings elucidate the risk of psychosocial strain during the early COVID-19 home confinement period in 2020. Therefore, in order to mitigate the negative psychosocial effects of home confinement, implementation of national strategies focused on promoting social inclusion through a technology-based solution is strongly suggested.

A label-free, microfluidics and interdigitated array microelectrode-based impedance biosensor in combination with nanoparticles immunoseparation for detection of Escherichia coli O157:H7 in food samples

Abstract: A microfluidic flow cell with embedded gold interdigitated array microelectrode (IDAM) was developed and integrated with magnetic nanoparticle-antibody conjugates (MNAC) into an impedance biosensor to rapidly detect pathogenic bacteria in ground beef samples. The flow cell consisting of a detection microchamber and inlet and outlet microchannels was fabricated by bonding an IDAM chip to a poly(dimethylsiloxane) (PDMS) microchannel. The detection microchamber with a dimension of 6 mm × 0.5 mm × 0.02 mm and a volume of 60 nL was used to collect bacterial cells in the active layer above the microelectrode for sensitive impedance change. MNAC were prepared by conjugating streptavidin-coated magnetic nanoparticles with biotin-labeled polyclonal goat anti-E. coli antibodies and were used in the separation and concentration of target bacteria. The cells of E. coli O157:H7 inoculated in a food sample were first captured by the MNAC, separated, and concentrated by applying a magnetic field, washed, and then suspended in mannitol solution and finally injected through the microfluidic flow cell for impedance measurement. This impedance biosensor was able to detect as low as 1.6 × 102 and 1.2 × 103 cells of E. coli O157:H7 cells present in pure culture and ground beef sample, respectively. The total detection time from sampling to measurement was 35 min. Equivalent circuit analysis indicated that the bulk medium resistance, double layer capacitance, and dielectric capacitance were responsible for the impedance change due to the presence of E. coli O157:H7 cells on the surface of IDAM. Sample pre-enrichment, secondary antibodies on the microelectrode surface, and redox probes were not required in this impedance biosensor.

Observation of Parity-Time Symmetry in Optically Induced Atomic Lattices

Abstract: We experimentally demonstrate PT-symmetric optical lattices with periodical gain and loss profiles in a coherently prepared four-level N-type atomic system. By appropriately tuning the pertinent atomic parameters, the onset of PT-symmetry breaking is observed through measuring an abrupt phase-shift jump between adjacent gain and loss waveguides. The experimental realization of such a readily reconfigurable and effectively controllable PT-symmetric waveguide array structure sets a new stage for further exploiting and better understanding the peculiar physical properties of these non-Hermitian systems in atomic settings.

Colloidal CdSe quantum wires by oriented attachment.

Abstract: We report here a relatively low temperature (100-180 degrees C) synthetic route to high-quality and single-crystalline CdSe nanowires using air-stable and generic chemicals. The diameter of nanowires was controlled and varied in an exceptionally small size regime, between 1.5 and 6 nm. This was achieved by using alkylamines, a single type or a mixture of two different types of amines, with different chain lengths and varying the reaction temperature. The experimental results suggest the coexistence of two types of fragments in the prewire aggregates, known as "pearl-necklace" or "string-of-pearls" in the literature, which are loosely associated and chemically fused sections.